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1
Toschi, Francesco. "Study of the electronic recoil background of the XENON1T experiment." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15785/.
Повний текст джерелаАнотація:
Uno dei principali protagonisti della caccia alla Materia Oscura è il Progetto XENON presso i LNGS, con l'obiettivo di rivelare le WIMP.
Forti dell'esperienza proveniente dalle precedenti fasi del Progetto, l'attuale esperimento XENON1T è il primo che contiene circa 3.2 t di xenon liquido, di cui circa 2 t costituiscono la massa attiva della TPC a doppia fase. E questa è la prima TPC con massa attiva superiore a 1 t e con il più basso livello di fondo tra tutti gli esperimenti di questo tipo.
Nel 2017, con un tempo di esposizione di soli 34.2 giorni, XENON1T ha ottenuto uno dei miglior limiti di esclusione per la sezione d'urto di interazione WIMP-nucleo non dipendente dallo spin.
Nella prima parte del presente lavoro di tesi, verifico la possibilità che il neutron generator (NG), una sorgente di neutroni per la calibrazione della risposta del rivelatore ai rinculi nucleari (NR), possa essere una sorgente di fondo per il rivelatore essendo posizionato vicino alla TPC.
Dalla stima del rate di eventi in presenza o meno del NG, nessuna differenza è stata osservata per gli eventi da rinculo elettronico (ER) a bassa energia.
Successivamente alla valutazione dell'attività di U238 e Th232 nei materiali del NG, è possibile stimare il fondo indotto da neutroni radiogenici atteso dal NG: poiché risulta essere due ordini di grandezza inferiore a quanto atteso dai materiali di costruzione del rivelatore, può essere considerato un contributo trascurabile.
Nella parte finale della tesi si presentano tutte le possibili sorgenti di fondo per eventi ER nel rivelatore di XENON1T e la simulazione, con il programma GEANT4, di tale fondo.
In particolare, è esaminata e discussa la nuova implementazione della simulazione per il doppio decadimento beta dell'isotopo Xe136.
Lo stato dell'arte del confronto delle simulazioni Monte Carlo con i dati reali è mostrato alla fine del lavoro di tesi: i risultati preliminari evidenziano una buona conoscenza del fondo dell'ER nel rivelatore XENON1T.
2
Corasaniti, Maria. "Monte Carlo simulation of a neutron veto for the XENONnT experiment." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13974/.
Повний текст джерелаАнотація:
XENON1T, located at the Laboratori Nazionali del Gran Sasso, is currently the largest experiment for direct dark matter search. It consists of a dual phase TPC filled with 2 tonnes of xenon, and has completed the first science run in January 2017, obtaining the most stringent exclusion limits on the spin-independent WIMP- nucleon interaction cross section for WIMP masses above 10 GeV/c2, with a minimum of 7.7·10−47 cm2 for 35-GeV/c2 WIMPs at 90% confidence level. Currently the experiment is still in data acquisition and aims at a sensitivity of 1.6 · 10−47 cm2 for WIMP masses of 50 GeV/c2 in 2 t·y exposure.
A next generation detector, called XENONnT, is already foreseen by the collaboration. It will have a larger TPC with an increased xenon target (∼ 6 t) which will improve the WIMP sensitivity by another order of magnitude. For this purpose, it also requires a very low background level. The expected neutron background for the new designed time projection chamber is ∼5 events in the 4 t fiducial volume, in the nominal 20 ton·year exposure. In this work we present a Monte Carlo simulation study of a Gd-loaded liquid scintillator neutron veto for the XENONnT experiment, with the goal of tagging the background events from radiogenic neutrons. Results indicate that, for a scintillating mixture with 0.1% of gadolinium by weight, and a light collection efficiency of ∼7%, we obtain a neutron rejection factor higher than 80%. This allows to reduce the neutron background by a factor ∼5, in order to be in full agreement with the background goal of the XENONnT experiment: <1 background event in the total exposure.
3
Rocchetti, Arianna. "MonteCarlo simulation of the XENON1T experiment and first comparison with the Muon Veto data." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13513/.
Повний текст джерелаАнотація:
L’esperimento XENON1T, in acquisizione dati presso i Laboratori Nazionali del Gran Sasso, è una Time Projection Chamber (TPC) contenente 2 t di xeno liquido ed ha come obiettivo una sensibilità per sezioni d'urto WIMP-nucleone indipendenti dallo spin pari a 1.6 10^(-47) cm^(2), per WIMP di massa 50 GeV/c^(2), in 2 t y. A tale scopo è fondamentale la riduzione di tutte le sorgenti di fondo. Per abbattere il fondo esterno la TPC è inserita all'interno di un Muon Veto: una vasca cilindrica riempita di acqua, dotata di 84 fotomoltiplicatori (PMT) , che funge sia da schermo passivo contro la radiazione esterna (gamma e neutroni), sia da veto per i muoni grazie alla rivelazione della luce Cherenkov da essi prodotta in acqua.
In questo lavoro presentiamo uno studio sulle configurazioni di trigger del Muon Veto e sulla sua efficienza. Lo studio è basato sul confronto di simulazioni Monte Carlo con i primi dati del rivelatore.
Si ottiene un'efficienza del 99.5% per eventi di muone e del 43% per sciami generati da interazioni del muone nella roccia che circonda la sala sperimentale, e conseguente riduzione degli eventi di background attesi nell'attuale run scientifico a 1.3 10^(-3) eventi.
È già previsto dalla collaborazione il futuro upgrade dell'esperimento: XENONnT. Uno studio sulle possibili geometrie della TPC di XENONnT è stato effettuato mediante simulazioni Monte Carlo. Tra le possibili migliorie apportabili a XENONnT vi è la sostituzione degli attuali sensori di luce con fotomoltiplicatori al silicio (SiPM).
Le simulazioni mostrano che, mediante una copertura totale della TPC con i SiPM, si ha un aumento dell'efficienza nella collezione di luce (LCE) del 20%. La LCE è un parametro fondamentale per la rivelazione del segnale di luce (S1) nella TPC; in questa configurazione si raggiunge una soglia in energia per rinculi nucleari di circa 3 keV, aumentando in modo significativo la sensibilità dell'esperimento, in particolare per WIMP di piccola massa.
4
Geis, Christopher Werner [Verfasser]. "The XENON1T water Cherenkov muon veto system and commissioning of the XENON1T Dark Matter experiment / Christopher Werner Geis." Mainz : Universitätsbibliothek Mainz, 2018. http://d-nb.info/116644936X/34.
Повний текст джерела
5
Massoli, Fabio Valerio <1987>. "The XENON1T experiment: Monte Carlo background estimation and sensitivity curves study." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6776/1/Massoli_FabioValerio_tesi.pdf.
Повний текст джерелаАнотація:
Despite the scientific achievement of the last decades in the astrophysical and cosmological fields, the majority of the Universe energy content is still unknown. A potential solution to the “missing mass problem” is the existence of dark matter in the form of WIMPs. Due to the very small cross section for WIMP-nuleon
interactions, the number of expected events is very limited (about 1 ev/tonne/year), thus requiring detectors with large target mass and low background level. The aim of the XENON1T experiment, the first tonne-scale LXe based detector, is to be sensitive to WIMP-nucleon cross section as low as 10^-47 cm^2.
To investigate the possibility of such a detector to reach its goal, Monte Carlo simulations are mandatory to estimate the background. To this aim, the GEANT4 toolkit has been used to implement the detector geometry and to simulate the decays from the various background sources: electromagnetic and nuclear. From the analysis of the simulations, the level of background has been found totally acceptable for the experiment purposes: about 1 background event in a 2 tonne-years exposure. Indeed, using the Maximum Gap method, the XENON1T sensitivity has been evaluated and the minimum for the WIMP-nucleon cross sections has been found at
1.87 x 10^-47 cm^2, at 90% CL, for a WIMP mass of 45 GeV/c^2. The results have been independently cross checked by using the Likelihood Ratio method that confirmed such results with an agreement within less than a factor two. Such a result is completely acceptable considering the intrinsic differences between the two statistical methods. Thus, in the PhD thesis it has been proven that the XENON1T detector will be able to reach the designed sensitivity, thus lowering the limits on the WIMP-nucleon cross section by about 2 orders of magnitude with respect to the current experiments.
6
Massoli, Fabio Valerio <1987>. "The XENON1T experiment: Monte Carlo background estimation and sensitivity curves study." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/6776/.
Повний текст джерелаАнотація:
Despite the scientific achievement of the last decades in the astrophysical and cosmological fields, the majority of the Universe energy content is still unknown. A potential solution to the “missing mass problem” is the existence of dark matter in the form of WIMPs. Due to the very small cross section for WIMP-nuleon
interactions, the number of expected events is very limited (about 1 ev/tonne/year), thus requiring detectors with large target mass and low background level. The aim of the XENON1T experiment, the first tonne-scale LXe based detector, is to be sensitive to WIMP-nucleon cross section as low as 10^-47 cm^2.
To investigate the possibility of such a detector to reach its goal, Monte Carlo simulations are mandatory to estimate the background. To this aim, the GEANT4 toolkit has been used to implement the detector geometry and to simulate the decays from the various background sources: electromagnetic and nuclear. From the analysis of the simulations, the level of background has been found totally acceptable for the experiment purposes: about 1 background event in a 2 tonne-years exposure. Indeed, using the Maximum Gap method, the XENON1T sensitivity has been evaluated and the minimum for the WIMP-nucleon cross sections has been found at
1.87 x 10^-47 cm^2, at 90% CL, for a WIMP mass of 45 GeV/c^2. The results have been independently cross checked by using the Likelihood Ratio method that confirmed such results with an agreement within less than a factor two. Such a result is completely acceptable considering the intrinsic differences between the two statistical methods. Thus, in the PhD thesis it has been proven that the XENON1T detector will be able to reach the designed sensitivity, thus lowering the limits on the WIMP-nucleon cross section by about 2 orders of magnitude with respect to the current experiments.
7
Di, Gangi Pietro. "Study of the sensitivity of the XENON1T experiment with the profile likelihood method." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8348/.
Повний текст джерелаАнотація:
Oggi sappiamo che la materia ordinaria rappresenta solo una piccola parte dell'intero contenuto in massa dell'Universo. L'ipotesi dell'esistenza della Materia Oscura, un nuovo tipo di materia che interagisce solo gravitazionalmente e, forse, tramite la forza debole, è stata avvalorata da numerose evidenze su scala sia galattica che cosmologica. Gli sforzi rivolti alla ricerca delle cosiddette WIMPs (Weakly Interacting Massive Particles), il generico nome dato alle particelle di Materia Oscura, si sono moltiplicati nel corso degli ultimi anni.
L'esperimento XENON1T, attualmente in costruzione presso i Laboratori Nazionali del Gran Sasso (LNGS) e che sarà in presa dati entro la fine del 2015, segnerà un significativo passo in avanti nella ricerca diretta di Materia Oscura, che si basa sulla rivelazione di collisioni elastiche su nuclei bersaglio. XENON1T rappresenta la fase attuale del progetto XENON, che ha già realizzato gli esperimenti XENON10 (2005) e XENON100 (2008 e tuttora in funzione) e che prevede anche un ulteriore sviluppo, chiamato XENONnT.
Il rivelatore XENON1T sfrutta circa 3 tonnellate di xeno liquido (LXe) e si basa su una Time Projection Chamber (TPC) a doppia fase. Dettagliate simulazioni Monte Carlo della geometria del rivelatore, assieme a specifiche misure della radioattività dei materiali e stime della purezza dello xeno utilizzato, hanno permesso di predire con accuratezza il fondo atteso.
In questo lavoro di tesi, presentiamo lo studio della sensibilità attesa per XENON1T effettuato tramite il metodo statistico chiamato Profile Likelihood (PL) Ratio, il quale nell'ambito di un approccio frequentista permette un'appropriata trattazione delle incertezze sistematiche.
In un primo momento è stata stimata la sensibilità usando il metodo semplificato Likelihood Ratio che non tiene conto di alcuna sistematica. In questo modo si è potuto valutare l'impatto della principale incertezza sistematica per XENON1T, ovvero quella sulla emissione di luce di scintillazione dello xeno per rinculi nucleari di bassa energia.
I risultati conclusivi ottenuti con il metodo PL indicano che XENON1T sarà in grado di migliorare significativamente gli attuali limiti di esclusione di WIMPs; la massima sensibilità raggiunge una sezione d'urto σ=1.2∙10-47 cm2 per una massa di WIMP di 50 GeV/c2 e per una esposizione nominale di 2 tonnellate∙anno. I risultati ottenuti sono in linea con l'ambizioso obiettivo di XENON1T di abbassare gli attuali limiti sulla sezione d'urto, σ, delle WIMPs di due ordini di grandezza. Con tali prestazioni, e considerando 1 tonnellata di LXe come massa fiduciale, XENON1T sarà in grado di superare gli attuali limiti (esperimento LUX, 2013) dopo soli 5 giorni di acquisizione dati.
8
Vargas, Miguel Ángel [Verfasser], and Christian [Akademischer Betreuer] Weinheimer. "Data analysis in the XENON1T Dark Matter Experiment / Miguel Ángel Vargas ; Betreuer: Christian Weinheimer." Münster : Universitäts- und Landesbibliothek Münster, 2019. http://d-nb.info/1191375730/34.
Повний текст джерела
9
Di, Gangi Pietro <1989>. "Dark Matter Search with the XENON1T Experiment: Background Predictions, Data Analysis and Final Results." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/9044/1/digangi-phd-thesis-final.pdf.
Повний текст джерелаАнотація:
The XENON1T experiment is currently the most sensitive in the world for the direct search for dark matter (DM). XENON1T employs a dual-phase (liquid-gas) time projection chamber (TPC) featuring 2.0 t liquid xenon (LXe) target mass. The detector is operated in the underground Laboratori Nazionali del Gran Sasso, in Italy. The search for WIMP, the most popular DMcandidate, conducted with the XENON1T detector for a total exposure of 1.0 t-y is presented in this work.
The measured background level amounts to $ 82^{+5}_{-3}\rm{(syst)\pm3\rm{(stat)}}\,(\si{t}\cdot\si{y}\cdot\si{keV})^{-1} $, the lowest ever achieved in a direct detection DM experiment.
The profile likelihood analysis of data collected in 278.8 live-days finds no significant excess over background. The statistical inference on the WIMP-nucleon spin-independent cross section sets the world-best exclusion limit for WIMP masses above 8\,GeV/c$ ^2 $, with a minimum of $ 4.1\times10^{-47} $\,cm$ ^2 $ at 30\,GeV/c$ ^2 $ and 90\% confidence level.
10
Brünner, Stefan Augustin [Verfasser], and Manfred [Akademischer Betreuer] Lindner. "Mitigation of 222Rn induced background in the XENON1T dark matter experiment / Stefan Augustin Brünner ; Betreuer: Manfred Lindner." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://d-nb.info/1178009297/34.
Повний текст джерела
11
Brünner, Stefan A. [Verfasser], and Manfred [Akademischer Betreuer] Lindner. "Mitigation of 222Rn induced background in the XENON1T dark matter experiment / Stefan Augustin Brünner ; Betreuer: Manfred Lindner." Heidelberg : Universitätsbibliothek Heidelberg, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:16-heidok-232613.
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12
Rupp, Natascha Margarita Rosa Elisabeth [Verfasser], and Undagoitia Teresa [Akademischer Betreuer] Marrodán. "Radon Induced Background in the XENON1T Dark Matter Search Experiment and Studies on Xenon Purity in the HeXe System / Natascha Margarita Rosa Elisabeth Rupp ; Betreuer: Teresa Marrodán Undagoitia." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1226541704/34.
Повний текст джерела
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Rupp, Natascha [Verfasser], and Undagoitia Teresa [Akademischer Betreuer] Marrodán. "Radon Induced Background in the XENON1T Dark Matter Search Experiment and Studies on Xenon Purity in the HeXe System / Natascha Margarita Rosa Elisabeth Rupp ; Betreuer: Teresa Marrodán Undagoitia." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1226541704/34.
Повний текст джерела
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Levy, Cecilia [Verfasser], and Christian [Akademischer Betreuer] Weinheimer. "Light propagation and reflection off teflon in liquid xenon detectors for the XENON100 and XENON1T dark matter experiments / Cecilia Levy ; Betreuer: Christian Weinheimer." Münster : Universitäts- und Landesbibliothek Münster, 2014. http://d-nb.info/113828226X/34.
Повний текст джерела
15
Pompa, Federica. "Neutrino physics with the XENONnT experiment." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19448/.
Повний текст джерелаАнотація:
One of the most active fields in physics is the search for Dark Matter, for which the XENON Project is one of the main protagonists. The new XENONnT experiment will be operative starting from 2020 in the underground Laboratori Nazionali del Gran Sasso, under 3600 meters water equivalent of mountain rock shield. It is a multi-ton detector for direct search of Dark Matter, consisting of a double phase liquid-gas xenon TPC which contains 5.9 t of liquid xenon target mass, inserted in a Cryostat surrounded by a tank containing 700 t of Gd-loaded water, instrumented with PMTs for muon and neutron tagging. Its aim, as that of its precursor XENON1T, is to detect WIMPs elastic scattering off xenon nucleus through the measure of the light and charge observable signals produced by recoils in LXe. A new neutron Veto system, surrounding the outer Cryostat and instrumented with 120 additional PMTs, will contribute to reduce the neutron background in the TPC. Thanks to the large xenon target used, this experiment is sensitive also to all flavors of Supernova neutrinos. These can be detected through two different interactions channels: through coherent elastic scatters on xenon nuclei in the TPC and through interactions of electron antineutrinos with protons of water via inverse beta decay process. In the first part of this work, after a theoretical introduction to neutrino physics, I present the results of a Monte Carlo simulation to predict the XENONnT detection efficiencies for neutrino events as IBD interactions in the neutron and muon Vetoes. In the last part of the thesis, I investigate the XENONnT possibility to detect neutrinoless double beta decay of Xe-136 isotope, a Standard Model forbidden decay which can prove the Majorana nature of neutrinos. Starting from evaluation of the ER background rate from Cryostat and PMTs in the energy region where we expect to observe neutrinoless double beta decay, the sensitivity of XENONnT for this nuclear decay was estimated.
16
Faxas, Miguel A. Jr. "Experiments in the dissociative recombination of xenon and krypton." FIU Digital Commons, 2005. http://digitalcommons.fiu.edu/etd/3288.
Повний текст джерелаАнотація:
Experiments were conducted using the Time of Flight (TOF) method to identify the final product states of the dissociative recombination reaction of krypton and xenon. In the dissociative recombination (DR) reaction the molecular ion breaks up into product atoms whose velocities can be measured. These velocities can then be used to identify the final product states. The DR of krypton had been studied by Shiu and Biondi using spectrometric techniques. They observed the 5p states. Hardy et al. using TOF techniques had observed the 5s states. Mitchell et al. studied the DR of xenon. They observed the 6p and 5d states of xenon. In this laboratory using the TOF method I have recently identified the 5s, 6p and the 4d final states of the DR of krypton. Then I was able to identify the 5d, 7s, 6d, and 6p' final product states of vi the DR of xenon. The study of the DR of these heavy inert gases can shed light on the theory of the DR of heavy polyatomic gases, which is not well developed.
17
Scovell, Paul Robert. "Results from the ZEPLIN-III dark matter search experiment." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/9592.
Повний текст джерелаАнотація:
The existence of a significant non-baryonic component to the Universe is widely accepted, with worldwide efforts underway trying to detect this so-called dark matter. The ZEPLIN-III detector utilises liquid xenon (Xe) as a target medium in the search for the expected rare interactions of Weakly Interacting Massive Particles, or WIMPs, with ordinary baryonic matter. The neutralino, arising in supersymmetric extensions to the standard model of particle physics, provides a particularly well-motivated candidate. The ZEPLIN-III experiment, operating in two-phase (liquid/gas) mode, measures both the scintillation and ionisation signatures produced during an interaction. The first science run (FSR) of ZEPLIN-III was performed during three months in 2008. The run culminated in a published result which excluded a WIMP-nucleon interaction cross-section above 8:1 x 10-8 pb for a 60 GeVc-2 WIMP at the 90% confidence level. ZEPLIN-III then entered an upgrade period where the photomultiplier tube (PMT) array, previously the dominant source of background, was replaced with new, ultra-low background, PMTs. The radio-contamination of components used to make these PMTs has been thoroughly studied and their impact on the background rates in ZEPLIN-III characterised. Additionally, a new 1.5 tonne plastic scintillator veto detector was constructed, increasing the ability to reject WIMPlike signals caused by neutron induced nuclear recoil events and improving the γ-ray discrimination capability of ZEPLIN-III. The second science run (SSR) of ZEPLIN-III began in June 2010 and continued for 6 months, with a projected upper limit for the interaction cross-section of 1:52 x 10-8 pb for a 55 GeVc-2 WIMP at the 90% confidence level.
18
Lee, Chang. "MITIGATION of BACKGROUNDS for the LARGE UNDERGROUND XENON DARK MATTER EXPERIMENT." Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1427482791.
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19
Le, Calloch Maxime. "Study of the single electron charge signals in the XENON100 direct Dark Matter search experiment." Nantes, 2014. https://archive.bu.univ-nantes.fr/pollux/show/show?id=f4984b95-6904-4ff8-bcd6-50f3768ac873.
Повний текст джерелаАнотація:
A partir de l’observation de l’Univers, il a été démontré que la masse associée à la matière visible ne représente que quelques pourcents de son budget énergétique total. La partie restante est composée de l’énergie noire, responsable de l’expansion cosmologique, et d’une matière invisible, la matière noire. La famille de particules la plus probable pour décrire cette matière noire est appelée WIMP. Ces particules peuvent être directement détectées par la mesure du recul nucléaire induit lors d’une diffusion élastique au sein d’un matériau scintillant. Pour cela, la Collaboration XENON a développé un détecteur placé sous terre, consistant en une chambre à projection temporelle (TPC) et utilisant du xénon sous deux phases: liquide et gazeuse. La différence de taux d’ionisation des atomes rencontrés pour un recul nucléaire induit par un WIMP, par rapport à un recul électronique induit par des sources de bruit de fond b ou g, conduit à des rapports différents entre les signaux émis en phase liquide et gazeuse. Cette différence est utilisée pour isoler les WIMPs du bruit de fond. Une bonne connaissance du signal d’ionisation est donc requise pour un tel détecteur. Dans ce contexte, la réponse du détecteur XENON100 aux signaux de charge d’électrons uniques est étudiée. Ils correspondent à des faibles signaux émis en phase gazeuse par un ou plusieurs électrons extraits en coïncidence temporelle. Grâce à cette analyse, une méthode innovante pour calculer le rendement d’extraction des électrons du liquide vers le gaz a été établieFrom the observation of the Universe, it has been demonstrated that the mass associated to visible matter represents only few percent of its energetic budget, while the remaining part is composed by dark energy, responsible to the cosmological expansion, and by some hidden matter, the dark matter. The likeliest particles family used to describe this dark matter is called WIMP (Weakly Interacting Massive Particles). That kind of particles could be directly detected by measuring nuclear recoil during an elastic scattering inside a scintillating material. For this, the XENON Collaboration has developed a detector consisting in a time projection chamber (TPC) using xenon dual phase (liquid and gas) detector, and placed underground. The different ionization density of nuclear recoils induced by WIMPs, and electronic recoils induced by β particles or g rays background source, leads to different ratio between both signals, in the liquid and in the gas phase, and is used to discriminate WIMPs from background. A good knowledge of the ionization signal is strongly required for such a detector. In this context, the XENON100 response to single electron charge signals is investigated. They correspond to very tiny signals emitted in the gas phase by one or few electrons extracted in time coincidence. Thanks to this analysis, an innovative method to establish the extraction yield of electrons from the liquid to the gas phase has been drawn, allowing to explore a key information to reject electronic recoils from nuclear ones
20
Bauermeister, Boris [Verfasser]. "Studies of calibration and electron recoil background modelling for the XENON100 dark matter experiment / Boris Bauermeister." Mainz : Universitätsbibliothek Mainz, 2017. http://d-nb.info/1122763220/34.
Повний текст джерела
21
Weber, Marc [Verfasser], and Wolfgang [Akademischer Betreuer] Hampel. "Gentle Neutron Signals and Noble Background in the XENON100 Dark Matter Search Experiment / Marc Weber ; Betreuer: Wolfgang Hampel." Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177249472/34.
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22
Balakishiyeva, Durdana Nazim. "Experimental investigations towards production of hyperpolarized xenon-129 through the condensed state." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.
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Whitis, Thomas James. "Measurement of Time Projection Chamber Optical Properties and Xenon Circulation System Development for The LZ Experiment." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1543947238765113.
Повний текст джерела
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Marzioni, Maria Francesca. "Axion dark matter and two-neutrino double electron capture searches in the Large Underground Xenon experiment." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31054.
Повний текст джерелаАнотація:
The hunt for Dark Matter plays a truly critical role in contemporary physics. At both the largest and smallest scales, deep questions are being raised about the fundamental nature of the universe - questions that confirmation and then characterisation of particle dark matter will provide many answers to. This thesis presents some of the world's most sensitive searches to date for certain types of axion dark matter, axion-like particles, and two-neutrino double electron capture. These have been conducted using the Large Underground Xenon (LUX) experiment. Evidence for dark matter and physics beyond the Standard Model of particle physics is described in Chapter 1, while Chapter 2 gives an overview of proposed candidates for particle dark matter. The various experimental approaches being used to detect particle dark matter are presented in Chapter 3. Direct detection with time projection chambers plays a major role in this thesis, with particular interest in the LUX detector, that is described in its components and operations. Chapter 4 presents LUX direct searches for weakly interacting massive particles. Although I have contributed to these analyses, they are included for completeness only, as they are not part of my central work. The LUX collaboration's searches for axion dark matter and axion-like particle have delivered world-leading results on the axion-electron coupling constant. These results, that I personally led and which have been published in Physics Review Letters, are presented in Chapter 5, along with sensitivity studies, also led by me, made for the future LUX-ZEPLIN experiment. Finally, a search for two-neutrino double electron capture of 124Xe, that I performed using LUX data to extract a limit on the half life of the process, is presented in Chapter 6. Although being allowed by the Standard Model, two-neutrino double electron capture shares the matrix element calculation framework with the neutrinoless channel of the same process, becoming of great interest in the scope of neutrino physics. Conclusions follow and close the thesis.
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Lamblin, Jacob. "XENON100 et MIMAC, des détecteurs à la recherche de matière noire." Habilitation à diriger des recherches, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00845580.
Повний текст джерелаАнотація:
Le document présente la problématique de la détection directe de matière noire dans le cadre des expériences XENON100 et MIMAC. Après une introduction générale sur la matière noire et sur les signaux attendus dans un détecteur terrestre, les deux projets sont passés en revue en se concentrant sur les aspects expérimentaux. L'accent est mis particulièrement sur la caractérisation des performances des détecteurs et sur les bruits de fonds associés.
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Öman, Mikael. "Intraperitoneal 5-Fluorouracil treatment of cancer - clinical and experimental studies." Doctoral thesis, Umeå University, Surgical and Perioperative Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-372.
Повний текст джерелаАнотація:
Background:Pancreas cancer is a most aggressive malignancy. More than 80% of patients diagnosed with pancreas cancer, exhibit such advanced disease, that curative surgery is impossible. Systemic chemotherapy prolongs survival to 5-9 months. High concentrations of chemotherapeutic agents in the abdominal cavity and in the lymphatics draining the area is achieved by intraperitoneal administration. Vasopressin decreases splanchnic blood flow, reducing the intraperitoneal uptake of drugs, thus raising the local and lymphatic dose intensity.
Aim: The aim of the study was to investigate the feasibility and tumour response of intraperitoneal 5-Fluorouracil (5-FU) treatment in non-resectable pancreas cancer, using vasopressin to improve the pharmacokinetic profile. Further, to study the effect of vasopressin on peritoneal blood flow, altered by intraperitoneal 5-FU or the presence of peritoneal carcinomatosis.
Methods: In the animal experiments, the 133Xe-clearance technique and as a comparison Laser doppler flow, were used to identify changes of peritoneal blood flow caused by vasopressin in unmanipulated animals and in animals with peritoneal carcinomatosis or animals given intraperitoneal 5-FU. In the clinical studies, 68 (39 women/29 men) patients, with a non-resectable ductal pancreas cancer and a Karnovsky Index ≥70 were included. Patients were treated with 750-1500 mg/m2 5-FU intraperitoneally through a Port-a-cath and Leucovorin 100 mg/m2 intravenously on two consecutive days every 21 days until progression. Seventeen patients, receiving 750 mg/m2 5-FU, were given concomitant vasopressin 0.1 IU/min during 180 minutes, alternatively day 1 or 2.
Results: In the animal experiments, vasopressin 0.07 IU/kg/min significantly reduced the 133Xe-clearance. Intraperitoneal 5-FU decreased the basal peritoneal blood flow and abrogated the vasopressin effect for 1-2 days. The presence of peritoneal carcinomatosis did not influence the basal peritoneal blood flow, nor the reduction of peritoneal blood flow caused by vasopressin. In the clinical studies, the treatment with intraperitoneal 5-FU was well tolerated, with no WHO Grade 3 or 4 toxicity with doses up to 1250 mg/m2. Thirty patients achieved at least stable disease at three months. The median survival time was 8.0 (range 0.8-54.1) months. There was a significant reduction of 5-FU Cmax on day 2, but no significant reduction of AUC, when vasopressin was given.
Conclusion: Peritoneal blood flow changes caused by vasopressin can be estimated with the 133Xe-clearance technique. Intraperitoneal 5-FU but not peritoneal carcinomatosis decreases the vasopressin induced 133Xe-clearance reduction, 1-2 days after administration. In patients with non-resectable pancreas cancer, intraperitoneal 5-FU up to 1250 mg/m2 for two days every third week can be given without WHO grade 3 and 4 toxicity. The treatment is well tolerated with few and minor side effects. Tumour responses were observed. Addition of vasopressin does not significantly enhance the pharmacokinetics of intraperitoneal 5-Flurorouracil, but adds toxicity.
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Crépisson, Céline. ""Missing Xenon" : experimental and theoretical study of Xe storage in crustal and upper mantle minerals." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS095.
Повний текст джерелаАнотація:
Un stockage du xénon dans les minéraux silicatés en profondeur a été proposé pour expliquer « le Xénon manquant », i.e. la faible teneur en Xe dans les atmosphères terrestre et martienne comparée à celle des chondrites et aux autres gaz rares. Néanmoins, il existe encore peu de données concernant l’incorporation du Xe dans les minéraux, due à sa très grande volatilité aux conditions ambiantes. Dans cette thèse, nous apportons de nouveaux éléments relatifs à l’incorporation du Xe dans les minéraux majeurs de la croûte continentale (quartz et feldspath) et du manteau supérieur (olivine). Des échantillons riches en Xe ont été synthétisés et caractérisés ex situ, avant d’être étudiés in situ à haute pressions et températures (T). Des calculs théoriques ont permis de proposer des mécanismes d’incorporation du Xe expliquant les observations expérimentales. Une substitution du Xe au site du Si est mise en évidence dans l’olivine et le quartz, avec la présence de liaisons Xe-O, partiellement covalentes (Xe-O = 1.98-2.09 Å). Jusqu’à 0.4 at% Xe pourrait être stocké dans l’olivine en profondeur et une transition de phase est observée dans le quartz à haute T, avec la formation de (Xe,Si)O2. En présence de Fe et Xe, une séparation de phase est observée entre une phase enrichie et une appauvrie en Fe dans l’olivine et le feldspath, Fe et Xe se stabilisant mutuellement. Enfin, la réactivité de Xe et Kr dans un verre et magma feldspathique est étudiée : Kr est oxydé et forme des liaisons courtes Kr-O (2.49 ± 0.1 Å). Ces nouveaux résultats insistent sur la nécessité de prendre en compte l’incorporation du Xe dans les minéraux silicatés en profondeur dans le cadre du « Xénon manquant »Storage of Xe in silicate minerals has been proposed to explain the ‘Missing Xenon’ issue, i.e. the low Xe abundance in the Earth’s and Mars’ atmospheres compared to other noble gases and chondrites. However, data about Xe incorporation in minerals remain scarce due to high Xe volatility preventing studies at ambient conditions. Xe incorporation in silicates has been proposed based on experimental evidences at high pressures (P) and temperatures (T). In this PhD thesis we bring new constraints on Xe incorporation in major Earth minerals of the continental crust (quartz and feldspar) and upper mantle (olivine). Xe-bearing samples have been synthesized, characterized ex situ and investigated in situ at high P-T conditions. Theoretical calculations have been performed to propose Xe incorporation sites able to reproduce experimental observations. In olivine and quartz, a Xe for Si substitution is likely, with the formation of at least partially covalent Xe-O bonds of 1.98-2.09 Å. Up to 0.4 at% Xe could be stored in olivine at depth, and in quartz a phase transition toward a new (Xe,Si)O2 phase is evidenced at high T. In presence of Fe and Xe, a phase separation is observed between a Fe-rich phase and a Fe-poor phase for feldspars and olivine, with Xe and Fe stabilizing each other. In presence of excess water, Xe is going into the fluid phase for olivine, while it is retained in a feldspathic melt. Eventually Kr and Xe reactivity in feldspathic glass and melt is evidenced with the observation of Kr oxidation and Kr-O short bonds (2.49 ± 0.1 Å). These constraints on Xe incorporation in silicate melts and minerals at depths could be crucial in the ‘Missing Xenon’ issue
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Gallaba, Gallaba Mudiyanselage Dinuka Harshana. "AN EXPERIMENTAL STUDY OF STRUCTURAL DEFORMATION AND “GATE OPENING” OF ZEOLITIC IMIDAZOLATE FRAMEWORK-8 UPON GAS SORPTION: THERMODYNAMIC AND KINETIC EVIDENCE." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/dissertations/1858.
Повний текст джерелаАнотація:
Volumetric adsorption experiments were conducted over three sorbates in Zeolitic Imidazolate Framework – 8 (ZIF-8). The sorption isotherms were measured at low temperatures. The study included carbon monoxide sorption in ZIF-8, xenon in ZIF-8, and methane sorption in ZIF-8. As a metal-organic framework that has been investigated thoroughly for its remarkable characteristics, ZIF-8 interactions with the above three sorbates has revealed some new features. Each of these systems offered a unique opportunity to study the physical properties of the sorbate and ZIF-8 and the thermodynamic responses of the system for its unique characteristics. The fundamental understating of sorbents-sorbate not only reveals some of the remarkable properties but also opens up new frontiers for researches in practical applications such as gas storage separation and other sorption-based fields of interest. The investigation into CO-ZIF-8 system has confirmed some of the predictions made on a similar system and analysis on the ZIF-8 structure. The measured adsorption isotherms have confirmed the existence of three pre-saturation subs steps, which were explained in terms of effects from the structural transition and polarity of the sorbate. The behavior of isosteric heat of adsorption and the equilibration time revealed a strong connection between steps in the isotherm and the structural changes of ZIF-8 due to organic linker rotation and volume expansion, also known as “Gate-Opening” in some cases. In both Xe-ZIF-8 and CH4 -ZIF-8 systems, the sorption isotherms revealed two substeps before the saturation. This is the first time such a feature was resolved experimentally in these systems although many previous studies have predicted the feature. The experimental observations on characteristics of the Xe -ZIF-8 system are also verified by computer simulations. Unlike the CO-ZIF-8 system, Xe-ZIF-8 interactions do not trigger the organic linker rotation of ZIF-8 structure, but it influenced the expansion of the ZIF-8 structure. In CH4 – ZIF-8 system the isotherms’ substeps were not as steep as Xe system but the loading dependence of isosteric heat of adsorption and equilibration time revealed features that are similar to CO. The lack of sorption-combined structural analysis of CH4-ZIF-8 prevent us from concluding the actual nature of the changes occurring which are related to the substeps and other thermodynamic and kinetic features. In all three systems, our measurements of the adsorption kinetics, we observed a non-monotonic behavior of the equilibration time as a function of sorbent loading. For CO the loading dependence of equilibration time exhibit peaks at loadings that correspond to the intermediate and higher loading sub-steps, and CH4 showed similar behavior at the loading corresponds to its intermediate substep region. The sharp peaks can be interpreted as packing rearrangement of adsorbed phase molecule in both cases and for CO there may be some contributions from the linker flipping and structural transition. The structural effect of kinetics is yet to be confirmed by a structural analysis for the CH4 system.
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Musselwhite, Donald Stanley. "Experimental geochemistry of iodine, argon and xenon: Implications for the outgassing histories of the Earth and Mars." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187095.
Повний текст джерелаАнотація:
This dissertation presents results from experiments measuring the silicate-melt solubility of iodine conducted at one atmosphere and the mineral/melt partitioning behavior of iodine, argon and xenon conducted at one atmosphere and 15kbars. The solubility of iodine in silicate melts is strongly correlated with the molar volume and the degree of polymerization of the melt. Results of mineral/melt partitioning studies show that iodine is at least ten times more incompatible than xenon. The values of argon mineral/melt partition coefficients determined in this study fall in the low range of those determined in previous investigations. These results, along with other parameters are used to assess the timing and extent of early mantle outgassing for the Earth and Mars. If outgassing alone is responsible for the xenon isotopic composition of the mantle source of the mid-ocean ridge basalts, then the mantle outgassed 99 percent of it's volatiles within the first 100 million years following the nucleosynthesis process, which preceded the formation of the solar system. Furthermore, the mantle experienced a nearly 100 percent molten state sometime during this period. Straight forward early outgassing cannot explain the isotopic composition of the martian atmosphere. A two-stage outgassing scenario can explain it, but requires the existence of an as yet unsampled mantle reservoir. Alternatively, water solubility fractionation very early in martian history may have played a significant role in determining the isotopic composition of the present-day martian atmosphere.
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McGrath, Caith Thomas. "An experimental study of electron transfer and emission during particle-surface interactions." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326351.
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GUARISE, MARCO. "An experimental study of novel schemes for low-energy-threshold and low-background particle detection in rare gas crystals." Doctoral thesis, Università degli studi di Ferrara, 2020. http://hdl.handle.net/11392/2488080.
Повний текст джерелаАнотація:
There are numerous indications about possible new physics beyond the Standard Model and in particular, one of the major issues refers to the Universe composition. Indeed, the ordinary matter, which is everything we know, seems to account for only a tiny fraction of the Cosmos' mass. The unknown part of the Universe mass is the so-called dark matter which represents one of the greatest mysteries of the modern science. Experimental evidences from cosmological and astrophysical observations in many different contexts, suggest the existence of dark matter particles that interact with ordinary matter mainly under the gravitational force. However, so far, all these particles evaded the detection and a direct proof of their existence is still missing.
To overcome this lack, novel complementary detection schemes are necessary to improve the actual limits and the performances of current detectors, opening thus the possibility to novel breakthrough discoveries.
This dissertation focuses on a research and development study for a new category of low-energy-threshold particle detector necessary to investigate low-energy-releases within the matter such as the direct investigation of dark matter composition.
In this thesis I will present two experimental schemes based on solid matrices of rare gas combined with the in-vacuum single electron detection technology. Small energy releases in unreactive materials, such as solid matrices of rare gas both pure and doped, can be probed exploiting also laser-assisted processes that up-convert the low-energy-release of the incident particle. These mechanisms should lead to a detectable electronic signal triggered by the incoming particle. In such a way, energy threshold ranging from meV to tens of eV could in principle be reached opening-up thus the possibility to probe theoretically well-motivated regions of unexplored electroweak parameter-space and thus test the existence of light dark matter candidates.
The work performed during the PhD period refers to the experimental research and development phases about: the rare gas crystals growing techniques and the corresponding set-ups, the electrons' extraction from rare gas crystals to the vacuum environment, and finally the spectroscopic studies on atomic species embedded into rare gas matrices.Oggigiorno, numerose prove sperimentali indicano che il Modello Standard della fisica delle particelle non sia completo, in particolare, una delle questioni più importanti riguarda la composizione dell'Universo. Infatti, la materia ordinaria, che è il costituente di tutto ciò che conosciamo, sembra essere solamente una minima frazione dell'intera massa del Cosmo stesso. La parte sconosciuta della massa dell'Universo viene indicata con il termine materia oscura e rappresenta uno dei più grandi misteri della scienza contemporanea. Le evidenze sperimentali sia su scala astrofisica sia cosmologica in contesti diversi, suggeriscono l'esistenza di particelle di materia oscura che interagiscono con la materia ordinaria mediante la forza gravitazionale. Nonostante queste osservazioni, fino ad ora, queste particelle non sono state mai misurate direttamente e quindi una prova diretta della loro esistenza tutt'ora manca. Per cercare di sopperire a questa lacuna è necessario migliorare le performance dei rivelatori attuali tramite nuovi schemi di rivelazione complementari, aprendo così la possibilità a nuove scoperte fondamentali. La presente dissertazione di dottorato si focalizza su uno studio di ricerca e sviluppo per una nuova categoria di rivelatori di particelle a bassa soglia energetica e a basso fondo. Tali approcci, necessari per investigare piccoli rilasci di energia nella materia, possono ad esempio essere applicabili allo studio della composizione particellare della materia oscura. In questa tesi verranno presentati due schemi sperimentali entrambi basati su matrici cristalline di gas rari o nobili quali neon argon kripton e xenon sia puri sia drogati con metalli alcalini o terre rare. Assieme a questi solidi, si intende sfruttare la tecnologia della rivelazione di singole cariche in vuoto che può essere ottenuta mediante strumenti quali microchannel-plate o channetron. Piccoli rilasci di energia in materiali isolanti quali solidi di gas rari sia drogati sia puri, possono infatti essere sondati da processi che sfruttano fenomeni quali la laser up-conversion per rivelare particelle debolmente interagenti. In questo modo, una soglia energetica che varia dal meV a decine di eV può essere in principio raggiunta, aprendo la possibilità all'indagine di regioni inesplorate dello spazio dei parametri dell'interazione elettrodebole, testando così l'esistenza di candidati leggeri per la materia oscura. Il lavoro che ho svolto durante il PhD riguarda la fase di ricerca e sviluppo relativa a: tecniche di crescita di cristalli di gas rari ed i relativi apparati sperimentali, l'estrazione di elettroni da questi solidi, ed infine studi spettroscopici su specie atomiche intrappolate all'interno di queste matrici cristalline.
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Templier, Claude. "Etude expérimentale de la précipitation dans les alliages à base d'aluminium obtenus par implantation ionique de Cu, Ag et Xe : demixtion et dissolution dans les alliages Al-Ag et Al-Cu, structure, formation et croissance des bulles de xenon." Poitiers, 1987. http://www.theses.fr/1987POIT2017.
Повний текст джерелаАнотація:
Analyse de la microstructure des alliages al-ag et al-cu fabriques par implantation ionique. Analyse des zones de guinier-preston et des phases intermediaires dans l'alliage al-cu irradie par des ions xenon de 300 kev. Mise en evidence des mecanismes de diffusion acceleree, diffusion balistique et precipitation. Pour les echantillons irradies avec des ions xenon, des bulles de xenon solide se forment. Etude de la demixion , du xenon dans des matrices d'aluminium: structure des bulles apres l'implantation , formation des bulles pendant l'implantation, evolution des bulles lors des traitements thermiques
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SAGE, FRANCOISE. "Pompage optique du niveau metastable **(3)p : :(o) de la premiere configuration excitee des isotopes impairs des gaz rares." Caen, 1985. http://www.theses.fr/1985CAEN2039.
Повний текст джерелаАнотація:
Etude experimentale de ce pompage optique sur les isotopes **(21)ne, **(83)kr, **(129)xe et **(131)xe afin de mesurer le facteur de lande g(**(3)po) par des experiences de resonance magnetique en phase vapeur (**(21)ne) ou son faisceau atomique, les atomes etant portes dans l'etat metastable a l'aide d'une decharge haute frequence et pompes optiquement par un laser a colorant continu accordable, avec une precision superieure a celle des calculs a partir de la structure hyperfine
34
Bernal, Nicolas. "Théorie et Phénoménologie du MSSM avec des Scalaires Lourds." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00447004.
Повний текст джерелаАнотація:
Ce mémoire de thèse sera consacré à l'étude de quelques aspects phénoménologiques de la supersymétrie avec, comme principaux sujets, d'une part, la physique du MSSM dans le cas où les superparticules scalaires sont lourdes et les implications possibles auprès de collisionneurs à haute énergie tels que le LHC et, d'autre part, les caractéristiques des particules de matière noire et leurs détermination auprès des collisionneurs et dans des expériences d'astroparticules.
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BANOUNI, MOSTAFA. "Effets de la topographie de surface induite par impact d'ions lourds sur la spectrometrie d'electrons secondaires resolue angulairement." Toulouse 3, 1986. http://www.theses.fr/1986TOU30135.
Повний текст джерелаАнотація:
Influence de la topographie de surface induite par bombardement ionique sur l'emission electronique secondaire. Presentation des resultats et description de modeles rendant compte des principeles topographiques observees sur differentes cibles d'aluminium bombardees par des ions argon et xenon de 25 kev
36
Girardeau, Thierry. "Etude des signaux exafs des laitons au cours de la transformation martensitique : mise au point d'un appareillage exafs de laboratoire adapte aux films minces." Poitiers, 1987. http://www.theses.fr/1987POIT2276.
Повний текст джерелаАнотація:
Etude par analyse du coefficient d'absorption, de la transformation martensitique dans les laitons cu-39%atzn et cu-15%atzn-17%atal. Mise au point d'un appareillage de mesure exafs afin d'obtenir des signaux caracteristiques des regions cristallines endommagees par implantation ionique. La methode consiste a faire penetrer les rayons x en incidence rasante puis a botenir une reflexion totale sur son support. Application au melange ionique des multicouches fe-al soumises a une implantation d'ions xenon
37
Alikhani, Mohammad Esmaïl. "Etude par spectroscopie de diffusion raman du piegeage de trois especes isotopiques de dihydrogene en matrice de gaz rares et d'azote : interpretation theorique des perturbations spectrales observees dans les gaz rares." Paris 6, 1988. http://www.theses.fr/1988PA066015.
Повний текст джерелаАнотація:
Comparaison des positions des raies des especes monomeres (h::(2),hd::(1),d::(2)) piegees dans des gaz rares (ar,kr,xe) aux valeurs calculees selon plusieurs modeles plus ou moins elabores. Bon accord pour h::(2) et d::(2); necessite d'un terme de couplage rotation-translation pour expliquer le deplacement vers les hautes frequences de la raie s::(0)(0) de hd. Interpretation des spectres d'agregats, observes apres recuits, par un modele d'oscillateurs couples : bon accord avec l'experience pour un taux ortho/para variable de h::(2) et d::(2) pour un agregat contenant au moins cinq molecules
38
Radouani, Abdelhak. "Réaction des atomes métastables de gaz rares (Ar*(3p2,0), Kr*(3p2) et Xe*(3p2)) avec le silane." Grenoble 1, 1986. http://www.theses.fr/1986GRE10143.
Повний текст джерелаАнотація:
Etude des produits de reactions par spectrometrie d'emission et de si a l'etat fondamental pas spectrometrie d'absorption. Absence d'emission dans le cas de xe et observation de la formation de si dans differents etats electroniques excites et de sih dans son 1er etat electronique excite, pour lesquels on determine les coefficients de chimiluminescence. Avantages de la technique de post-decharge en ecoulement. Emploi d'un modele statistique pour interpreter l'evolution des populations des niveaux rotationnels de sih**(*) par collision avec ar
39
Hami, Mohamed. "Spectroscopie du mélange helium-xénon : rôle du monoxyde de carbone : analyse cinétique dans l'ultra-violet lointain." Toulouse 3, 1988. http://www.theses.fr/1988TOU30169.
Повний текст джерелаАнотація:
Etude spectroscopique des gaz purs et des melanges he-xe, excites par des particules alpha , entre 110 et 600 nm. Dans he observations de transitions moleculaires a 164 et 365 nm, et, en presence de co, du 1er systeme negatif (absence de v'=2). Dans xe, observation de deux continuums en uv proche et lointain et de la 2eme raie de resonance. Dans les melanges he-xe, observation en plus de la 1ere raie de resonance de xe avec renforcement des emissions de he par xe. Dans les melanges ne-co, emission du 1er systeme negatif et du 4eme systeme positif de l'ion et de la molecule; renforcement des emissions par addition de xe. Etude cinetique du 2nd continuum de xe dans les melanges he-xe a 173 nm (importance des processus heteronucleaires pour l'emission de l'excimere de xe) et du 4eme systeme positif dans les melanges ne-co (processus reactionnels a deux corps)
40
Contreras, Palacios Hugo Alejandro. "Research and Development of the Purification and Cryogenic Systems for the XENON1T Dark Matter Experiment." Thesis, 2015. https://doi.org/10.7916/D8WH2P43.
Повний текст джерелаАнотація:
The evidence supporting the presence of Dark Matter in the universe ranges over many length scales: from the rotational curves within galaxies that cannot be explained only by the dust and other visible component to the anisotropies in the cosmological microwave background that sets the most precise quantification for the DM content in the universe at 26.8% of the energy density. One of the candidates for DM with the most theoretical support is a family of particles that appear in extensions of the Standard Model of Particles. These new particles, known as Weakly Interacting Massive Particles (WIMPs), provide a natural solution to the missing mass in the universe that interact only via weak interaction and whose origin dates back from the very early universe. The XENON Dark Matter search experiments aim to the direct detection of WIMPs via scattering off xenon nuclei. Following the success of the first prototype, XENON10, the XENON100 detector has been, up to late 2013, the most sensitive DM detector setting an upper bound limit on the spin-independent WIMP-nucleon cross-section of 2. × 10 −45 cm 2 and the spin-dependent equivalent of 3.5 × 10 −44 cm 2 . The detector consists of a dual-phase xenon Time Projection Chamber (TPC) with an inner target of 62 kg, located at the un- derground facility at Laboratori Nazionali del Gran Sasso (LNGS) in Italy. XENON100 is still in operation, currently testing new calibration sources of potential use for the next generation XENON1T experiment, under commissioning in Hall B of LNGS, aims to im- prove the XENON100 sensitivity by two orders of magnitude by increasing the xenon target mass in the detector to the tonne scale and by reducing the intrinsic background rate and consequently, increase the expected number of WIMP events per year. The scale-up of a liquid xenon TPC imposes many technical challenges that needed to be addressed prior to the realization of the XENON1T phase of the project. The focus of my thesis work has been the research and development of Dark Matter detectors operated with a xenon mass at the tonne scale. In particular, the topic of purification of a large amount of Xe gas to reduce the concentration of electronegative impurities to levels below afew parts per billion in a reasonable amount of time has been a driver in my work with the XENON1T Demonstrator facility at the Columbia Nevis laboratories. Two complementary approaches were followed in order to address this problem: i) a study of the performance of XENON100 concerning the electron lifetime (eLT) among other parameters that depend on the purity and ii) the construction of a full-size Xe TPC prototype to test multiple technologies with the goal of an optimized XENON1T TPC, with several tonnes of Xe. In addition to my work on the XENON1T Demonstrator, I have also contributed to the operation and analysis of data from XENON100. In particular, I developed a cut based on the information theory concept of entropy to reduce the electronic noise in the data. A detailed description of the motivation and implementation of the entropy cut is presented in Chapter 3. The experience gained from the successful performance of XENON100 and the information from variety of measurements with the XENON1T Demonstrator have influenced the design of XENON1T and will impact other next-generation Dark Matter detectors using LXe in a TPC. More specifically, the design of the XENON1T cryogenic system which is at the heart of the experiment, has been guided by this experience. The testing of the system was performed at Nevis where the various components were assembled and leak checked before being shipped to LNGS. The XENON1T detector’s cryostat and its cryogenics system, designed by the Columbia University XENON group were installed underground in the Hall B of the LNGS laboratory in Summer/Fall 2014. Their commissioning represent a major milestone in the realization of XENON1T. The last chapter of the thesis summarizes the status of XENON1T, with particular focus on the design of the cryogenic, purification and cryostat system influenced by the R & D with the Demonstrator.
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Zhang, Yun. "The Cryogenic Infrastructure of the XENON1T Dark Matter Experiment: from Design to Performance during the One Ton-Year WIMP Search." Thesis, 2021. https://doi.org/10.7916/d8-3jtp-qd41.
Повний текст джерелаАнотація:
An abundance of evidence from a wide range of astrophysical and cosmological observations suggests the existence of nonluminous cold dark matter, which makes up about 83% of the matter and 27% of the mass-energy of the Universe. Weakly Interacting Massive Particles (WIMPs) have been one of the most promising dark matter candidates. Various detection techniques have been used to directly search for the interaction in terrestrial detectors where WIMP particles are expected to scatter off target nuclei. Over the last fifteen years, dual-phase time projection chambers (TPCs) with liquid xenon (LXe) as target and detection medium have led the WIMP dark matter search. The XENON dark matter search project is a phased program focused on the direct detection of WIMPs through a series of experiments employing dual-phase xenon TPCs with increasing target mass operated at the Gran Sasso underground laboratory (LNGS) in Italy. The XENON1T experiment is the most recent generation, completed at the end of 2018. The XENON1T dark matter search results from the one ton-year exposure have set the most stringent limit on the WIMP-nucleon spin-independent elastic scatter cross-section over a wide range of masses, with a minimum upper limit of 4.1 x 10⁻⁴⁷ cm² at 30 GeV · c⁻² and a 90% confidence level.
XENON1T is the first WIMP dark matter experiment which has deployed a dual-phase xenon TPC at the multi-ton scale, with 3.2 t of LXe used. The large xenon mass posed new challenges in reliable and stable xenon cooling, in achieving and maintaining ultra-high purity as well as in efficient and safe xenon storage, transfer and recovery. The Cryogenic Infrastructure was designed and constructed to solve these challenges. It consists of four highly interconnected systems --- the Cryogenic System, the Purification System, the Cryostat and Cryogenic Pipe, and the ReStoX System. The XENON1T Cryogenic Infrastructure has performed successfully and will continue to serve the next generation experiment, called XENONnT, with a new Cryostat containing a total of 8.4 tons of xenon.
I first give an instrument overview of the systems in XENON1T. I then review the cooling methods in LXe detectors which led to the design of the cooling system implemented in the XENON1T experiment, and suggest a design of the cooling system for future LXe dark matter experiments at the 50 tons scale. I describe and discuss in detail the design and the performance of the XENON1T Cryogenic Infrastructure. Finally, I describe the detector stability and the corresponding data selection in all three XENON1T science runs, and describe the dark matter search results from the one ton-year exposure.
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Chatterjee, Shiuli. "Phenomenological Explorations in Dark Matter." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5707.
Повний текст джерелаАнотація:
The previous decade has seen an explosive increase in explorations into the nature of dark matter (DM) encompassing astrophysical, particle and cosmological probes. We face today a large body of gravitational evidences supporting the existence of dark matter and yet must grapple with ambiguity about its particle nature. This makes it one of the most important and challenging questions in physics, with a wide range of implications. Of particular interest is the interplay between the particle nature of dark matter and its astrophysical and cosmological manifestations. In this thesis, we address a few important questions regarding the possible properties of dark matter.
The thesis consists of two parts. The first part explores lepton flavored dark matter (LFDM). One of the main results of this part is the connection between the stability of dark matter and the symmetries it possesses. We systematically show that many representations of lepton flavored dark matter are stable under the minimal flavor violation (MFV) hypothesis as long as there are no lepton number violating interactions. As a special case of the stability condition, we show that DM carrying certain charges under lepton number are trivially stable from lepton number conservation alone. We then study the cases of freeze-in mechanisms for relic density production and their detection phenomenology. We see that the LFDM in the MFV framework naturally accommodates a freeze-in production. Additionally, the notoriously difficult to detect freeze-in mechanism leads to some observable signatures at present and future direct detection experiments in minimal models of LFDM.
In the second part of the thesis, we explore two important questions related to direct and indirect searches for dark matter. The latest results from the direct detection experiment XENON1T achieved unprecedentedly low background rates in electron recoil events for O(keV) recoil energies, with the future experiment XENONnT projected to lower it even further. Motivated by this, we explore the reach of XENON1T experiment in probing inelastic dark matter. We consider a dark sector consisting of two Majorana fermions χ1 and χ2 that form a pseudo-Dirac state with O(keV) mass splitting. We study the freeze-in production of the DM along with constraints from lepton colliders, flavor factories, beam dumps, and supernova cooling in the relevant parameter space. We then study the direct detection of the DM by assuming the lighter state makes up the full DM abundance in current epoch. We show then that direct detection process is enabled only by up-scattering of the dark matter in the Sun, followed by a down-scattering in electron recoil events at direct detection experiments on Earth. This leads to constraints from the current results from XENON1T experiment. We also find that hitherto unconstrained parameter space will be probed at the XENONnT experiment.
The second question addresses whether neutron stars can be used as reliable probes of particle dark matter. For concreteness, we focus on the case where dark matter is captured by muons leading to kinetic heating in old neutron stars. The temperatures of old neutron stars can be probed at near-future telescopes like the James Webb Space Telescope (JWST). Our results show that the capture rates and subsequently the temperatures of the neutron stars are crucially dependent on the dark matter properties as opposed to the astrophysical properties of the neutron stars, like equation-of-state, velocity of the neutron star, dark matter halo distribution, etc. This, we believe, sets the path for neutron stars to become reliable laboratories of dark matter properties.
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"Direct Dark Matter Search with the XENON100 Experiment." Thesis, 2012. http://hdl.handle.net/1911/70350.
Повний текст джерелаАнотація:
Dark matter, a non-luminous, non-baryonic matter, is thought to constitute 23 % of the matter-energy components in the universe today. Except for its gravitational effects, the existence of dark matter has never been confirmed by any other means and its nature remains unknown. If a hypothetical Weakly Interacting Massive Particle (WIMP) were in thermal equilibrium in the early universe, it could have a relic abundance close to that of dark matter today, which provides a promising particle candidate of dark matter. Minimal Super-Symmetric extensions to the standard model predicts a stable particle with mass in the range 10 GeV/c 2 to 1000 GeV/c 2 , and spin-independent cross-section with ordinary matter nucleon σ x ∠ 1 × 10 -43 cm 2 . The XENON100 experiment deploys a Dual Phase Liquid Xenon Time Projection Chamber (LXeTPC) of 62 kg liquid xenon as its sensitive volume, to detect scintillation ( S1 ) and ionization ( S2 ) signals from WIMP dark matter particles directly scattering off xenon nuclei. The detector is located underground at Laboratori Nazionali del Gran Sasso (LNGS) in central Italy. 1.4 km of rock (3.7 km water equivalent) reduces the cosmic muon background by a factor of 10 6 . The event-by-event 3D positioning capability of TPC allows volume fiducialization. With the self-shielding power of liquid xenon, as well as a 99 kg liquid xenon active veto, the electromagnetic radiation background is greatly suppressed. By utilizing the difference of ( S2/S1 ) between electronic recoil and nuclear recoil, the expected WIMP signature, a small nuclear recoil energy deposition, could be discriminated from electronic recoil background with high efficiency. XENON100 achieved the lowest background rate (∠ 2.2 × 10 -2 events/kg/day/keV) in the dark matter search region (∠ 40 keV) among all direct dark matter detectors. With 11.2 days of data, XENON100 already sets the world's best spin-independent WIMP-nucleon cross-section limit of 2.7 × 10 -44 cm 2 at WIMP mass 50 GeV/c 2 . With 100.9 days of data, XENON100 excludes WIMP-nucleon cross-section above 7.0 × 10 -45 cm 2 for a WIMP mass of 50 GeV/c 2 at 90% confidence level.
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Plante, Guillaume. "The XENON100 Dark Matter Experiment: Design, Construction, Calibration and 2010 Search Results with Improved Measurement of the Scintillation Response of Liquid Xenon to Low-Energy Nuclear Recoils." Thesis, 2012. https://doi.org/10.7916/D89P37MT.
Повний текст джерелаАнотація:
An impressive array of astrophysical observations suggest that 83% of the matter in the universe is in a form of non-luminous, cold, collisionless, non-baryonic dark matter. Several extensions of the Standard Model of particle physics aimed at solving the hierarchy problem predict stable weakly interacting massive particles (WIMPs) that could naturally have the right cosmological relic abundance today to compose most of the dark matter if their interactions with normal matter are on the order of a weak scale cross section. These candidates also have the added benefit that their properties and interaction rates can be computed in a well defined particle physics model. A considerable experimental effort is currently under way to uncover the nature of dark matter. One method of detecting WIMP dark matter is to look for its interactions in terrestrial detectors where it is expected to scatter off nuclei. In 2007, the XENON10 experiment took the lead over the most sensitive direct detection dark matter search in operation, the CDMS II experiment, by probing spin-independent WIMP-nucleon interaction cross sections down to σχN ~ 5 × 10-44 cm2 at 30GeV/c2. Liquefied noble gas detectors are now among the technologies at the forefront of direct detection experiments. Liquid xenon (LXe), in particular, is a well suited target for WIMP direct detection. It is easily scalable to larger target masses, allows discrimination between nuclear recoils and electronic recoils, and has an excellent stopping power to shield against external backgrounds. A particle losing energy in LXe creates both ionization electrons and scintillation light. In a dual-phase LXe time projection chamber (TPC) the ionization electrons are drifted and extracted into the gas phase where they are accelerated to amplify the charge signal into a proportional scintillation signal. These two signals allow the three-dimensional localization of events with millimeter precision and the ability to fiducialize the target volume, yielding an inner core with a very low background. Additionally, the ratio of ionization and scintillation can be used to discriminate between nuclear recoils, from neutrons or WIMPs, and electronic recoils, from γ or β backgrounds. In these detectors, the energy scale is based on the scintillation signal of nuclear recoils and consequently the precise knowledge of the scintillation efficiency of nuclear recoils in LXe is of prime importance. Inspired by the success of the XENON10 experiment, the XENON collaboration designed and built a new, ten times larger, with a one hundred times lower background, LXe TPC to search for dark matter. It is currently the most sensitive direct detection experiment in operation. In order to shed light on the response of LXe to low energy nuclear recoils a new single phase detector designed specifically for the measurement of the scintillation efficiency of nuclear recoils was also built. In 2011, the XENON100 dark matter results from 100 live days set the most stringent limit on the spin-independent WIMP-nucleon interaction cross section over a wide range of masses, down to σχN ~ 7 x 10-45 cm2 at 50GeV/c2, almost an order of magnitude improvement over XENON10 in less than four years. This thesis describes the research conducted in the context of the XENON100 dark matter search experiment. I describe the initial simulation results and ideas that influenced the design of the XENON100 detector, the construction and assembly steps that lead into its concrete realization, the detector and its subsystems, a subset of the calibration results of the detector, and finally dark matter exclusion limits. I also describe in detail the new improved measurement of the important quantity for the interpretation of results from LXe dark matter searches, the scintillation efficiency of low-energy nuclear recoils in LXe.
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Garcia, Alexandre Nuno de Carvalho Amaral. "Gaseous mixtures-detection media studies for the NEXT experiment: a contribution." Master's thesis, 2012. http://hdl.handle.net/10316/25170.
Повний текст джерелаАнотація:
The purpose of this Master thesis is to contribute to the NEXT experiment (Neutrino Experiment
with a Xenon Time Projection Chamber) by studying xenon based gaseous mixture
properties. The work developed to study gaseous mixtures properties was based on three experimental
setups: Ion Drift Chamber (IDC), Gas Proportional Scintillation Counter (GPSC)
and Proportional Counter (PC).
With the IDC, measurements of Ne and N2 ion mobilities in their parent gases were performed
and the mobility of xenon ion in the Xe-N2 mixture was also measured. These measurements
were performed at low pressures (4 to 16 Torr) and reduced electric elds between
6 and 35 Td. For the Xe-N2 mixture, the amount of dopant (N2) ranged from 0 to 10%. The
results attained for Ne and N2 were in good agreement with other authors results. It could be
concluded that adding nitrogen to xenon increases the xenon ion mobility. The results show
that adding 10% of N2 increases xenon ion mobilities by almost 6%.
The part of the work developed with the GPSC was the optimization of the rst NEXT
prototype - NEXT-0. The task proposed was to optimize the setup to overcome its major
limitation: not being able to operate at high electric elds. Although not fully accomplished,
the limitation was minimized, thus allowing for normal operation up to at least 1.5 bar. Another
limitation that prevented normal operation was caused by non-desired radiation being
detected, impairing the detection of the radioactive source. This limitation was fully overcome.
Furthermore, data was acquired and it was possible to observe that pressure interferes with the
resolution behaviour of the detector. The drift and electroluminescence elds applied are also
correlated with the detector's resolution behaviour. In this way, the results obtained seem to
show that more pressure improves resolution and that also diminishes the electroluminescence
eld requirements (it does not need to be as intense).
In the last part of the experimental work, a cylindrical proportional counter was projected,
assembled and tested, and is working simultaneously and in parallel with a GPSC, in a specially
designed Ultra-High-Vacuum system. Although the GPSC is not fully working yet, preliminary
data has already been successfully obtained with the PC.
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Dawson, Troy. "Development of a xenon polarizer for magnetometry in neutron electric dipole moment experiments." 2013. http://hdl.handle.net/1993/21694.
Повний текст джерелаАнотація:
Next generation electric dipole moment experiments require precise knowledge of the local magnetic fields in the experimental volume. Hyperpolarized xenon-129 has been proposed as a comagnetometer gas to be used in the neutron electric dipole moment experiment planned for TRIUMF. A flow through xenon polarizer was constructed and tested, and the hyperpolarized Xe-129 produced was transported to and characterized using a new AFP-NMR spectrometer. The polarization measured in the external AFP-NMR spectrometer was (12 ± 4)%. The longitudinal spin relaxation time T1 was found to be (77 ± 24) s in the experimental NMR volume, limited by leaks and field inhomogeneity. This represents good progress towards the eventual system for nEDM experiments where polarizations greater than 50% and T1, T2 relaxation times greater than 1000 s are expected.
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Freitas, Elisabete Dinora Caldas de. "Studies on High Pressure Xenon Scintillation and Photosensor Alternatives for the next Experiment." Doctoral thesis, 2013. http://hdl.handle.net/10316/24597.
Повний текст джерела
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Jorge, Marina Rodrigues. "Experimental measurement of the electroluminescence yield of pure xenon and mixtures of xenon with percentage quantities of CH4." Master's thesis, 2014. http://hdl.handle.net/10316/28098.
Повний текст джерелаАнотація:
Dissertação de Mestrado em Engenharia Física apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.A Eletroluminescência (EL), como método de amplificação de sinal da ionização primária produzida em gases nobres, em contadores gasosos de cintilação proporcional (CGCP), desenvolvidos na década de 1970, tem desempenhado um papel importante em aplicações a diversas áreas, tais como astronomia, física dos plasmas e física das altas energias, até meados dos anos 1990 com a evolução dos detetores de estado sólido. No entanto, nos últimos anos a EL recuperou importância em experiências para a deteção de eventos raros, como a procura de matéria negra e do decaimento beta duplo. NEXT (Neutrino Experiment in a xenon TPC) é uma colaboração internacional que tem como objetivo medir o decaimento beta duplo sem emissão de neutrinos, 0νββ, no isótopo 136Xe. Estudos recentes de simulação Monte Carlo realizados em Coimbra apontam tendências diferentes para cada gás adicionado ao xénon. Enquanto a presença de CH4 em quantidades da ordem de um por cento ou inferior não tem impacto importante na redução de EL, a adição de CF4 reduz significativamente a EL, mesmo em quantidades de algumas décimas percentuais. Um compromisso deve ser encontrado entre a redução de EL e a quantidade de impurezas moleculares a adicionar ao xénon. É de grande importância para a colaboração NEXT que estes estudos de I&D sejam realizados, tanto experimentalmente como por simulação. O Grupo de Instrumentação Atómica e Nuclear (GIAN) do Centro de Instrumentação da Universidade de Coimbra tem grande experiência na área, tendo ficado a seu cargo a realização de estudos detalhados sobre este tema. No presente trabalho, foram realizadas medidas relativas do rendimento de EL em xénon e em misturas de xénon usando um CGCP sem região de deriva com um campo elétrico uniforme. Outros parâmetros investigados, incluindo a amplitude, resolução em energia e velocidade de deriva, foram medidos em função do campo elétrico reduzido na região de cintilação. Os resultados obtidos são concordantes com os resultados de simulação de Monte Carlo.
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Mano, Rui Daniel Passos. "Experimental Measurement of the Electroluminescence Yield, Electron Drift Velocity and Intrinsic Energy Resolution for Mixtures of Xenon with sub-percentage quantities of CO2 for the NEXT Experiment." Master's thesis, 2015. http://hdl.handle.net/10316/29816.
Повний текст джерелаАнотація:
Dissertação de Mestrado em Física, apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.A natureza dos neutrinos é uma das questões mais importantes na atualidade da física. A sua resposta terá um grande impacto em diferentes campos da física, como por exemplo na física de partículas, na cosmologia e na física experimental de neutrinos. Esta natureza pode ser testada através da deteção do processo de decaimento beta duplo sem emissão de neutrinos. Se este decaimento se confirmar não haverá dúvida de que os neutrinos são partículas de Majorana, em vez de partículas de Dirac, como o Modelo Padrão da Física de Partículas assume. A experiência NEXT está a desenvolver uma TPC com xénon a alta pressão e que usa o processo de eletroluminescência como meio de amplificação do sinal de ionização primária, causada pelas interações da radiação com o meio gasoso. O processo de eletroluminescência permite uma amplificação de sinal efetiva com reduzidas flutuações estatísticas quando comparadas com o processo de amplificação de sinal através de multiplicação em carga. É necessário atingir uma resolução em energia muito boa para obter uma discriminação eficiente do decaimento beta duplo sem emissão de neutrinos no xénon, tanto do fundo provocado pelas interações gama, como do próprio decaimento beta duplo com emissão de neutrinos. Este último é um mecanismo algumas ordens de grandeza mais frequente do que o ββ0ν. A capacidade de reconhecimento da topologia da ionização primária do evento ββ0ν possibilitará uma posterior distinção dos eventos ββ dos eventos resultantes das interações gama. No entanto, o xénon é um gás muito lento com elevada difusão de eletrões, sendo estes fatores uma desvantagem para a distinção acima referida. A adição de aditivos moleculares ao xénon puro terá um impacto significativo na redução da difusão da nuvem de eletrões primária e no aumento da velocidade de deriva dos eletrões na mistura. Contudo, estes aditivos causarão também uma redução do rendimento de cintilação da mistura e um aumento das flutuações estatísticas associadas à produção de eletroluminescência uma vez que o eletrão de deriva, ao colidir com uma molécula, irá perder parte da sua energia cinética para os estados vibracionais e rotacionais desta, não havendo desta forma produção de cintilação. Portanto, terá de ser feito um compromisso entre a concentração de aditivo molecular e a redução do rendimento de eletroluminescência ou o aumento das flutuações estatísticas associadas à produção de eletroluminescência, sendo este o estudo efetuado neste trabalho.
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Peres, Ricardo José Mota. "Contributions to the Xenon dark matter experiment: simulations of detector response to calibration sources and electric field optimization." Master's thesis, 2018. http://hdl.handle.net/10316/86267.
Повний текст джерелаАнотація:
Dissertação de Mestrado em Física apresentada à Faculdade de Ciências e TecnologiaA Matéria Escura continua a ser dos maiores mistérios do atual mundo da Física, potenciando imensos esforços no estudo do seu comportamento e das suas propriedades, tanto a nível experimental como teórico. Os detetores XENON tentam detetar de forma direta estas esquivas partículas, focando-se principalmente nas Partículas Pesadas que Interagem por Força Fraca, ou WIMPs, em grandes volumes de Xenon líquido com detetores de Câmaras de Projeção Temporal (TPC) de dupla fase. Desde a publicação dos seus últimos resultados, o detetor XENON1T é reconhecido como a mais sensível experiência de Matéria Escura.Neste trabalho, enumeram-se as principais evidências da existência de Matéria Escura no Universo e alguns dos seus mais reconhecidos modelos teóricos, passando depois à apresentação do detetor XENON1T e, de seguida, do futuro detetor XENONnT. O principal foco desta dissertação é, numa primeira instância, a simulação e análise de calibrações de recuos nucleares (NR) com um gerador de neutrões (NG), feitas no detetor XENON1T. Uma simulação de todo o detetor é feita para estudar o comportamento esperado e os resultados de análise comparados com os resultados em dados do detetor real. Mais ainda, é de seguida feita uma análise a outras campanhas de calibração com o NG de forma a estudar e modelar a banda de recuos nucleares. Mais tarde, no último capítulo, o foco muda para a construção do modelo geométrico e simulações de elementos finitos de campo elétrico da TPC do detetor XENONnT. Aqui, o principal objetivo é otimizar a geometria e diferencças de potencial aplicadas aos anéis de deformação do campo elétrico(FSR), responsáveis por o manter o mais uniforme possível dentro da TPC.
Dark Matter (DM) still stands as one of the great mysteries of current day Physics, fueling massive experimental and theoretical endeavors to understand its behavior and properties. The XENON detectors aim to directly detect these elusive particles, mostly focusing on Weakly Interactive Massive Particles, or WIMPs, in a large volume of liquid Xenon, using double phase time projection chamber (TPC) detectors. Since its latest results published, the XENON1T detector stands as the most sensitive Dark Matter experiment up to date.In this work, a journey through the evidences on the existence of Dark Matter in the Universe and some of its most notorious models leads to a presentation of the current generation XENON1T detector and, later on, the next generation XENONnT detector. The core of this dissertation focuses, at first, on the simulation and analysis of neutron generator (NG) nuclear recoil (NR) calibration data from the XENON1T detector. Here, a full simulation of a NG calibration run is computed and its results compared with data taken with the XENON1T detector. A separate analysis of other NR calibration data to look into the NR band model and ots empirical fit is achieved. Later, in the last chapter, the focus changes to the construction of the geometry model and electric field finite-element simulation of the XENONnT TPC. The main objective is to optimize the resistive chain that ensures the uniformity of the field inside the TPC, changing the geometry and voltage of the field shaping rings, preliminary based on the design used for XENON1T.