Дисертації з теми "Nuclear astrophysic"
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MASHA, ELIANA. "ASTROPHYSICAL NUCLEAR REACTIONS ON NEON ISOTOPES AT LUNA." Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/899089.
Повний текст джерелаGNECH, ALEX. "Theoretical calculation of nuclear reactions of interest for Big Bang Nucleosynthesis." Doctoral thesis, Gran Sasso Science Institute, 2020. http://hdl.handle.net/20.500.12571/14971.
Повний текст джерелаMarta, Michele. "The 14N(p,γ)O15 reaction studied at low and high beam energy". Forschungszentrum Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-93642.
Повний текст джерелаMARCELLI, LAURA. "PAMELA mission: in flight perfomances and preliminary measurements of nuclear abundances." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/639.
Повний текст джерелаPAMELA (a “Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics”) experiment is a satellite-borne apparatus designed for precision studies of the charged particles in the cosmic radiation. The primary scientific goal is the study of the antimatter component of the cosmic radiation (antiprotons, 80 MeV - 190 GeV; and positrons, 50 MeV - 270 GeV) in order to search for evidence of dark matter particle annihilations. PAMELA will also search for primordial antinuclei (in particular, anti-helium), and test cosmic-ray propagation models through precise measurements of the antiparticle energy spectrum and studies of light nuclei and their isotopes. In addition, it will measure the light nuclear component of cosmic rays and investigate phenomena connected with Solar and Earth physics. PAMELA is installed inside a pressurized container attached to a Russian Resurs DK1 earth-observation satellite that was launched into space in an elliptical (350 - 600 km of altitude) orbit with an inclination of 70.0 degrees by a Soyuz-U rocket on June 15th 2006 from the Baikonur cosmodrome in Kazakhstan. The PAMELA apparatus comprises a magnetic spectrometer, a Time of Flight system, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The combination of these devices allows antiparticles to be reliably identified from a large background of other charged particles. The semipolar orbit (70.0°) allows PAMELA to investigate a wide range of energies for antiprotons (80 MeV - 190 GeV) and positrons (50 MeV - 270 GeV). Three years of data taking will provide unprecedented statistics in this energy range and will set the upper limit for the ratio anti-He/He below 10^(-7). Before launch and during the first months of data taking, Quick Look Software (for mission monitoring in real time) and Data Analysis Software were developed. Furthermore measurements of the the light attenuation lengths and trigger efficiencies of the TOF scintillator system in the "flight" configuration were performed. Preliminary results of Boron to Carbon nuclear ratio in cosmic rays in the energy range from 200 MeV/n up to 25 GeV/n have been derived using combined data from Calorimeter, Tracker and TOF systems. This measurement is very important to put constraints to propagation parameters of cosmological models and, as a consequence, to make more easily visibile a possible small contamination from primary sources in antiprotons and positrons spectra. A better determination of the cosmic ray propagation is fundamental for the search of exotic matter, like dark matter candidates or antimatter produced in exotic processes, since the signature of such processes can be recognized only by knowing with great precision the fluxes due to the conventional production, acceleration and transport mechanisms.
Szabo, Anthony Paul. "High energy emissions for astrophysical objects." Title page, contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phs996.pdf.
Повний текст джерелаDoherty, Daniel Thomas. "Experimental studies for explosive nuclear astrophysics." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/18022.
Повний текст джерелаMumby-Croft, Paul David. "Tactic : A New Detector for Nuclear Astrophysics." Thesis, University of York, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507686.
Повний текст джерелаTABASSAM, UZMA. "A Pair Spectrometer for Nuclear Astrophysics Applications." Doctoral thesis, Università degli Studi di Camerino, 2012. http://hdl.handle.net/11581/401785.
Повний текст джерелаRuiz, C. "Aspects of nuclear phenomena under explosive astrophysical conditions." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/11338.
Повний текст джерелаLuis, Hélio Fernandes. "Study of nuclear reactions relevant for astrophysics by Micro-AMS." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/11274.
Повний текст джерелаThis work of this thesis was dedicated to the application of the Micro-AMS(Accelerator Mass spectrometry with micro-beam) to the study of nuclear reactions relevant to Astrophysics, namely reactions involving the radioisotope 36Cl. Before this could be done, the system had to be installed, tested and optimized. During the installation and testing phase, several isotopes were measured, principally lead and platinum isotopes, which served to show the potential of this technique for applications to Material science and archeology. After this initial stage, the work with 36Cl began. 36Cl is one of several short to medium lived isotopes (as compared to the earth age) whose abundances in the earlier solar system may help to clarify its formation process. There are two generally accepted possible models for the production of this radionuclide: it originated from the ejecta of a nearby supernova (where 36Cl was most probably produced via the s-process by neutron irradiation of 35Cl) and/or it was produced by in-situ irradiation of nebular dust by energetic particles(mostly, p, a, 3He -X-wind irradiation model). The objective of the present work was to measure the cross section of the 35Cl(n,γ)36Cl nuclear reaction which opened the possibility to the future study of the 37Cl(p,d)36Cl and 35Cl(d,p)36Cl nuclear reactions, by measuring the 36Cl content of AgCl samples with Micro-AMS, taking advantage of the very low detection limits of this technique for chlorine measurements. For that, the micro-AMS system of the CTN-IST laboratory had to be optimized for chlorine measurements, as to our knowledge this type of measurements had never been performed in such a system (AMS with micro-beam). This thesis presents the results of these developments, namely the tests in terms of precision and reproducibility that were done by comparing AgCl blanks irradiated at the Portuguese National Reactor with standards produced by the dilution of the NIST SRM 4943 standard material. With these results the cross section of the 37Cl(n,γ)36Cl was calculated.
Depalo, Rosanna. "The neon-sodium cycle: Study of the 22Ne(p,gamma)23Na reaction at astrophysical energies." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424304.
Повний текст джерелаLa reazione 22Ne(p,gamma)23Na fa parte del ciclo neon-sodio per il bruciamento dell' idrogeno. Il ciclo neon-sodio gioca un ruolo fondamentale per la sintesi degli elementi con massa A = 20-25 nelle stelle in fase di asymptotic giant branch, nelle esplosioni di novae di tipo classico e nelle esplosioni di supernovae di tipo Ia, dove il bruciamento di idrogeno avviene ad alte temperature. In particolare, la reazione 22Ne(p,gamma)23Na è la più incerta del ciclo neon-sodio. L'incertezza sulla sezione d'urto è dovuta al contributo, alle energie di interesse astrofisico, di un gran numero di risonanze. Alcune di queste risonanze non sono mai state osservate, per altre, invece, l'intensità è conosciuta con grande incertezza. Per misurare la sezione d'urto della 22Ne(p,gamma)23Na alle energie di interesse astrofisico, due esperimenti sono stati condotti nell'ambito di questa tesi: il primo, svolto con l'apparato sperimentale di LUNA, ha permesso di esplorare le risonanze di energia inferiore a 400 keV. Il secondo, invece, è stato svolto all'Helmoltz-Zentrum Dresden-Rossendorf (HZDR), in Germania, ed ha permesso di miglirare la precisione sulle intensità delle risonanze tra 400 e 660 keV. Per la misura svolta al Gran Sasso è stato usato un bersaglio di tipo gassoso senza finestre di ingresso e i fotoni emessi nel decadimento del 23Na sono stati osservati con due rivelatori al germanio. L'esperimento svolto a LUNA ha permesso di rivelare per la prima volta tre risonanze. Per queste risonanze sono stati osservati anche nuovi modi di decadimento gamma. Questo ha permesso di ampliare gli schemi di decadimento di letteratura. Questa misura ha permesso, inoltre, di ridurre di due ordini di grandezza i limiti superiori sulle intensità di tre risonanze la cui esistenza è tuttora dubbia. Per l'esperimento svolto all'HZDR è stato utilizzato un bersaglio solido di 22Ne e due rivelatori al germanio circondati da schermi anti Compton. I target sono stati realizzati all'impiantatore da 200 kV dei Laboratori Nazionali di Legnaro impiantando il 22Ne su una targhetta di tantalio. L'intensità delle risonanze tra 400 e 660 keV è stata misurata usando come riferimento le risonanze a 1279 keV e 478 keV, che sono intense e ben note. Questo esperimento ha permesso di ridurre l'incertezza sull'intensità della risonanza a 436 keV di un fattore tre, mentre, per la risonanza a 661 keV, è stata determinata un'intensità un ordine di grandezza inferiore rispetto alla letteratura. Il rate di reazione astrofisico è stato aggiornato tenendo conto dei nuovi risultati descritti sopra. Alle temperature caratteristiche delle esplosioni di novae di tipo classico, l'incertezza sul nuovo rate è un ordine di grandezza inferiore rispetto alla letteratura.
Álvarez, Pastor José Manuel. "Focal plane detectors of a Laue lens telescope for Nuclear Astrophysics." Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/83940.
Повний текст джерелаfew MeV) has an extraordinary potential for understanding the evolving and violent Universe. In spite of the strong efforts accomplished by past and current instruments, in order to perform observations in this energy range, an improvement in sensitivity over present technologies is needed to take full advantage of the scientific potential contained in this energy range. In order to achieve higher sensitivities, γ-ray astronomy has been looking over the last decades for new ways to increase the efficiency of its instruments while reducing the background noise. With the objective of reducing or avoiding as much background as possible (through shielding mechanisms and data analysis techniques), a strong effort in innovation and design (build-up of prototypes and numerical simulations studies) is being conducted by a community facing the challenge of preparing the next generation of γ-ray telescopes. In particular, the progress achieved during the last decade on focusing optics based on Laue lenses is especially remarkable. Conceptually, a focusing telescope will reduce drastically the background noise by concentrating γ-rays onto a small size detector. Focusing γ-rays with a Laue lens is not just a theoretical concept, but a reality, mainly thanks to the development of a first prototype of Laue lens for nuclear astrophysics accomplished as part of the CLAIRE project. Moreover, the development of focusing optics during these years has also encouraged the development of new detector technologies. The focal plane detector of a focusing telescope should provide imaging capabilities, perform high-resolution spectroscopy and measure the polarization of the incident photons in order to achieve the ambitious scientific goals. The research presented in this thesis covers both main areas of a γ-rays telescope: focusing optics and focal plane detector. As far as the optics is concerned, a test of the lens CLAIRE was performed in order to confirm the principles of a Laue diffraction lens. Concerning the focal plane detector, theoretical and experimental studies with new detector technologies have been carried out. Our main research has evolved in the framework of two mission concept studies -GRI (2007) and DUAL (2010)- submitted to the ESA Calls for a Medium-size mission opportunity within the Cosmic Vision 2015-2025 program. As far as the GRI mission is concerned, a focal plane detector configuration based on Cd(Zn)Te pixelated detectors is proposed, whilst development and testing of a detector prototype is accomplished. It is noteworthy that the detector configuration was successfully registered under a European Patent and is being considered for applications in the field of nuclear medicine. Regarding the DUAL mission, simulations of the expected space radiation environment and the resulting detector activation were carried out in order to estimate the performances of the all-sky Compton telescope of DUAL (based on Germanium-strip detectors). The results show that DUAL could achieve, after two years of operation, a continuum sensitivity one order of magnitude better than any past and current observatory in the MeV energy range and up to a factor 30 of improvement with its Laue lens. Beyond the detector technology proposed for GRI and DUAL, a wide variety of technologies could be explored for the focal plane of a γ-ray lens mission as well as for a stand-alone detector. In this thesis a focal plane detector based on liquid xenon is also considered. This work faces the challenges of the next generation of γ-ray telescopes, where high performance γ-ray detectors are necessary to achieve the required sensitivity in order to answer several hot scientific topics of Gamma-ray astrophysics in the energy range of nuclear transitions.
Lonardoni, Diego. "From Hypernuclei to Hypermatter: a Quantum Monte Carlo Study of Strangeness in Nuclear Structure and Nuclear Astrophysics." Doctoral thesis, Università degli studi di Trento, 2013. https://hdl.handle.net/11572/368865.
Повний текст джерелаAl, Mamun Md Abdullah. "Nuclei, Nucleons and Quarks in Astrophysical Phenomena." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1563991151449461.
Повний текст джерелаMASCARETTI, CARLO. "Open problems in neutrino astrophysics." Doctoral thesis, Gran Sasso Science Institute, 2020. http://hdl.handle.net/20.500.12571/15041.
Повний текст джерелаMalatji, Kgashane Leroy. "Nuclear level densities and gamma-ray strength functions in Ta isotopes and nucleo-synthesis of ¹⁸ᴼTa". University of the Western Cape, 2016. http://hdl.handle.net/11394/5321.
Повний текст джерелаMost stable and extremely low abundance neutron deficient nuclei with Z ≥ 34 are referred to as p-nuclei. Nearly all p-nuclei with A < 110 are most likely produced in the rp-process while almost all A > 110 are thought to be produced by the photodisintegration of s- and r- process seed nuclei. However, for some nuclear systems, these processes are not sufficient to explain their observed solar abundance. Results from calculations in ¹⁸ᴼTa generally provoke debates since several processes are able, sometimes exclusively, to reproduce the observed ¹⁸ᴼTa abundance in the cosmos, making it a unique case study. Some of the main sources of errors in the predicted reaction rates of ¹⁸ᴼTa arise due to the absence of nuclear data or due to large uncertainties in the nuclear properties such as the nuclear level densities (NLD) and gamma-ray strength functions (γSF) of ¹⁸ᴼ,¹⁸¹Ta. The NLD and γSF are primary ingredients for astrophysical reaction rate calculations based on the Hauser-Feshbach approach. These parameters need to be well understood to improve our understanding of ¹⁸ᴼTa production in astrophysical environments. In this thesis, new experimental data for the low-energy part of the γSF and NLD in ¹⁸ᴼ,¹⁸¹Ta were extracted, using the so-called Oslo method. An experiment was performed and the NaI(Tl) gamma-ray array and silicon particle telescopes at the Oslo cyclotron laboratory were utilized to measure particle-γ coincidence events from which the NLDs and γSFs are extracted below the neutron separation energy threshold Sn. A beam of ³He was used to populate excited states in ¹⁸ᴼ,¹⁸¹Ta through the inelastic scattering (³He,³He’𝛾) and the transfer reaction (³He,𝜶𝛾). Based on results from this measurements, the Maxwellian averaged (n, 𝛾) cross sections for the 179Ta(n, γ) and ¹⁸ᴼTa(n, 𝛾) reactions, at the s-process thermal energy of kT = 30 keV (i.e. a temperature of T = 3.5 × 10⁸ K) and p-process thermal energy of 215 keV (T = 2.5 × 10⁹ K), respectively, were computed with the TALYS reaction code. These results can be used to place the nuclear physics aspects of the large network abundance calculations on a solid footing and have potential to improve our understanding of the astrophysical processes and sites involved in the production of nature’s rarest isotope ¹⁸ᴼTa.
National Research Foundation (NRF)
Harss, Boris Peter Mathias Sascha. "Development of a radioactive 17F beam and its use in nuclear astrophysics experiments." [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=962379883.
Повний текст джерелаAltana, Carmen Loredana. "The role of nanostructured targets in Laser-Produced Plasmas for Nuclear Astrophysics studies." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3737.
Повний текст джерелаGalaviz, Redondo Daniel [Verfasser]. "Systematic study of alpha-nucleus potentials for neutron-deficient nuclei and its astrophysical applications / Daniel Galaviz Redondo." Aachen : Shaker, 2004. http://d-nb.info/1172614768/34.
Повний текст джерелаDay, Francesca. "Astrophysical signatures of axion-like particles." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:215f6432-6dbb-4a16-80d8-3ad0bc76ec2d.
Повний текст джерелаWallace, Jennifer Patrita. "Studies of the structure of the Tz = -1 Nuclei 20Na and 30S for explosive astrophysics." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8039.
Повний текст джерелаLaird, Alison M. "An investigation of the d(18Ne,19Ne*)p reaction and its astrophysical relevance." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/1755.
Повний текст джерелаHubbard, Nicolas. "Studies of the nuclear structure of 12C and the astrophysical production of 23Na." Thesis, University of York, 2018. http://etheses.whiterose.ac.uk/20690/.
Повний текст джерелаMei, Bo [Verfasser], René [Akademischer Betreuer] Reifarth, and Yuri A. [Akademischer Betreuer] Litvinov. "Nuclear reactions for astrophysics with storage rings / Bo Mei. Gutachter: René Reifarth ; Yuri A. Litvinov." Frankfurt am Main : Univ.-Bibliothek Frankfurt am Main, 2014. http://d-nb.info/1071902482/34.
Повний текст джерелаBradfield-Smith, William. "Measurement of the ¹⁸Ne(α,p)²¹Na reaction rate, and its implications for Nuclear Astrophysics". Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/12614.
Повний текст джерелаCota, Stephen A. "The astrophysics of nebulae and active galactic nuclear emission-line regions : new methods and applications /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487331541707918.
Повний текст джерелаMichelagnoli, Caterina. "The lifetime of the 6.79 MeV state in 15O as a challenge for nuclear astrophysics and gamma-ray spectroscopy: a new DSAM measurement with the AGATA Demonstrator array." Doctoral thesis, Università degli studi di Padova, 2013. http://hdl.handle.net/11577/3426648.
Повний текст джерелаLa determinazione della sezione d'urto delle reazioni termonucleari nelle stelle è una delle sfide più impegnative per l'astrofisica nucleare. Per comprendere questo ed altri processi nucleari che avvengono nel mezzo stellare sono fondamentali gli esperimenti di fisica nucleare con tecniche e strumentazioni sempre più avanzate. In questo lavoro di tesi, è stato utilizzato per la prima volta un apparato d'avanguardia per la spettroscopia gamma per un esperimento di interesse astrofisico e, cioè, una nuova misura della vita media dello stato a 6.79 MeV nel nucleo 15O, utilizzando il metodo del Doppler shift attenuato. Una determinazione accurata di questa quantità è, infatti, di estrema importanza per ricavare il fattore astrofisico S e la corrispondente sezione d'urto della reazione 14N(pγ)15O, la più lenta del ciclo CNO. Verranno quindi presentati e discussi i risultati di una nuova misura diretta della vita media dello stato in questione. I primi stati eccitati del nucleo 15O (e 15N) sono stati popolati attraverso i meccanismi di fusione-evaporazione e di trasferimento di nucleoni nella reazione 14N + 2H (impiantato sulla superficie di 4mg/cm2 di uno strato di oro) ad una energia di 32 MeV, con il fascio di 14N accelerato dal Tandem XTU dei Laboratori Nazionali di Legnaro. I raggi gamma prodotti nella reazione sono stati rivelati mediante quattro rivelatori compositi (clusters tripli) del dimostratore di AGATA, posti all'indietro rispetto alla linea di fascio, consentendo una misura, in modo continuo, della distribuzione angolare dei raggi gamma. La risoluzione in energia e la sensibilità alla posizione di interazione di questo modernissimo spettrometro gamma sono stati utilizzati per misurare vite medie nel range dei fs mediante il “Doppler Shift Attenuation Method". Il contributo degli effetti dovuti alla vita media sulle forme di riga dei picchi gamma, rispetto a quelli legati alla cinematica dei nuclei emessi è stato estratto mediante dettagliate simulazioni Monte Carlo della emissione e rivelazione della radiazione gamma. A questo scopo sono stati effettuati calcoli in canali accoppiati del processo di trasferimento di nucleoni. Trattandosi di uno dei primi esperimenti in cui tale spettrometro d’avanguardia è coinvolto, verranno discussi in dettaglio i vari passaggi dell’analisi dei dati e dello sviluppo di una parte di codice Monte Carlo. Il confronto tra gli spettri sperimentali e simulati per raggi gamma di energia molto alta, che diseccitano stati nucleari di pochi fs, verrà mostrato per la transizione di 6.79 MeV nel nucleo 15O e per alcuni livelli del nucleo 15N. Vengono presentati anche i dettagli dell’analisi del chi-quadro, essenziale per ottenere i risultati. I valori di vita media ottenuti per gli stati eccitati del nucleo 15N vengono confrontati con i risultati noti in letteratura. L’analisi dei dati conclusiva ha permesso di dare un nuovo limite alla vita media del livello a 6.79 MeV del nucleo 15O.
Bemmerer, Daniel. "Precise nuclear physics for the Sun." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-95439.
Повний текст джерелаDenke, Robson Zacarelli. "Fator S astrofisico para a reação de captura 4He(t,g)7Li pela investigação da reação de transferência elástica no sistema 7Li + 4He." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-30052007-170452/.
Повний текст джерелаThe normalization coefficient for the non-resonant part of the 3H(alpha,gama)7Li capture reaction (or alternately, the astrophysical S-factor) was obtained with the indirect method ANC (Asymptotic Normalization Coefficients). In this method the spectroscopic factor (or alternately, the ANC) is extracted from the investigation of a peripheral transfer reaction, which involves the same vertex as the corresponding capture reaction. Usually transfer reactions have two vertexes and the spectroscopic factor for one of them has to be known to obtain the other. In this work we investigate the 4He(7Li,4He)7Li elastic transfer reaction to obtain the spectroscopic factor and ANC for the 4He + t = 7Li bound system. The elastic transfer process, where the elastic and transfer exit channels are the same, has the advantage of having only one unknown vertex. Thus, the combined analysisof the angular distribution for elastic 4He(7Li,7Li)4He, and transfer process 4He(7Li,4He)7Li, allowed the extraction of the spectroscopic factor (and ANC) for the <3H|4He>=7Li bound system in an unique way. Angular distributions for these processes were measured at the Pelletron Laboratory at the center of mass energies of 9.67 MeV and 10.62 MeV. In these measurements, the 7Li beams with 26.6 MeV and 29.2 MeV were obtained from the Sao Paulo Pelletron accelerator. A 4He gas target and a double-slit collimator system were used. The 7Li scattered particles and alpha particles from transfer reaction were both detected at forward angles by a set of delta E - E silicon detectors telescopes. A Monte Carlo simulation code was developed to calculate the solid angle for the collimator system near the zero degree. A global optical potential parameters set for the 7Li + 4He system were defined using the measured elastic scattering angular distribution and other angular distributions obtained from the literature at different energies (from ~ 7-32 MeV). These optical potential parameters were used in the DWBA (Distorted Wave Born Approximation) analysis to describe the tritium transfer reaction contribution in the angular distributions. The obtained spectroscopic factor for the <3H,4He>=7Li bound system is S = 0.55+-0.03 and the ANC coefficient C2 = 17.5+-1.0 fm-1. With these results, the 3H(alpha,gama)7Li direct capture cross sections and astrophysical S-factor were calculated.
Postnikov, Sergey A. "Topics in the Physics and Astrophysics of Neutron Stars." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1259174094.
Повний текст джерелаCurran, Dian Beard. "Magnetic shearing instabilities in accretion disks /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
Повний текст джерелаKafexhiu, Ervin [Verfasser], and Felix [Akademischer Betreuer] Aharonian. "Radiation signatures of nuclear reactions in very hot astrophysical plasmas / Ervin Kafexhiu ; Betreuer: Felix Aharonian." Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177380919/34.
Повний текст джерелаRojas, Folkers Eduardo. "Evaluation, design, and construction of the Wallace Astrophysical Observatory Camera for astronomical observations." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54464.
Повний текст джерела"May 2008." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 53-54).
The goal of this thesis is to upgrade the scientific capabilities of the 24" Cassegrain reflector telescope at the George R. Wallace, Jr. Astrophysical Observatory (Wallace Observatory), part of Massachusetts Institute of Technology (MIT). The upgrade consists of evaluating, designing and constructing the Wallace Astrophysical Observatory Camera (WAOcam), optimized for 24" telescope. A full 3D model of the 24" telescope and dome was created to find the size restrictions for WAOcam. An optical model was also developed to maximize the field of view of the camera detector. WAOcam was designed using SolidWorks (3D modeling Software), the parts files from the designing process were also used to machine the instrument. The manufacturing of the WAOcam involved using the following: Computer Numerical Control (CNC) lathe, CNC mill, drill press, and a Waterjet (cutting machine). The manufacturing process also required learning of Omax (software for the Waterjet) and MasterCam 9.1 (software for the CNC lathe and CNC mill). The resulting product is WAOcam, which consists of three modules: 1) vacuum dewar (houses a CCD detector), 2) shutter (controls when light hits the camera detector), and 3) filter wheel (modifies the light before hitting the detector). The remaining work left on the WAOcam is the installation of two additional modules: 1) a four port instrument rotator and 2) a field rotator. This upgrade will allow for occultation observations, strip scanning surveys, and Kuiper Belt Object (KBOs) astrometry to be obtained using the 24" telescope.
by Folkers Eduardo Rojas.
S.B.
Bemmerer, Daniel. "Precise nuclear physics for the sun." Forschungszentrum Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-97364.
Повний текст джерелаRöder, Marko. "Measurement of the Coulomb dissociation cross sections of the neutron rich nitrogen isotopes 20,21N." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-157725.
Повний текст джерелаViele neutronenreiche Kerne sind im schnellen Neutroneneinfangprozess (r-Prozess, engl. für rapid) involviert. Der r-Prozess bildet einen wichtigen Pfad für die Nukleosynthese schwerer Elemente und verläuft entlang der Neutronen-Dripline. Astrophysiker schlugen Kernkollaps-Supernovae innerhalb eines neutrinogetriebenen Windes als mögliches astrophysikalisches Szenario für den r-Prozess vor. Dabei werden alle zuvor gebildeten Elemente in Protonen, Neutronen und Alphapartikel dissoziiert. Außerdem ist von Berechnungen mit Reaktionsnetzwerken bekannt, dass leichte neutronenreiche Kerne einen hohen Einfluss auf die Elementverteilung des r-Prozesses haben. Reaktionen dieser exotischen Kerne können nur mit radioaktiven Ionenstrahlen studiert werden, da ihre Halbwertszeiten im Bereich von wenigen hundert Millisekunden (T1/2,19N=330ms) zu gering sind, um Probenmaterial daraus herzustellen. Zwei Beispiele solcher Reaktionen, die auf dem Pfad des r-Prozesses liegen, sind die 19N(n,γ)20N und die 20N(n,γ)21N Reaktionen. Unter Verwendung von 20N (bzw. 21N) als Strahl wurden diese Reaktionen am Fragment Separator (FRS) der GSI unter zeitumgekehrten Bedingungen mittels Coulomb-Aufbruch gemessen, indem das virtuelle Photonenfeld einer Bleiprobe ausgenutzt wurde. Das Experiment wurde am LAND/R3B Aufbau (Large Area Neutron Detector, Reactions with Relativistic Radioactive Beams) in einer kinematisch vollständigen Messung durchgeführt, d.h. alle ausgehenden Reaktionsprodukte wurden detektiert. Die relativistischen Neutronen wurden mit dem LAND-Detektor untersucht. Dessen Kalibration spielt eine wichtige Rolle für die hier analysierten Reaktionen. Dabei wurde der Smiley-Effekt studiert, welcher beinhaltet, dass die gemessene Energie von einfallenden Teilchen mittels langen Szintillatorstreifen nicht unabhängig von der Position ist, an der die Teilchen auf den Detektor treffen. Es wird gezeigt, dass Reflexionen des Lichtes beim Durchgang durch den Szintillator und die größere Weglänge, die das Licht zurücklegen muss, wenn es nicht direkt in Richtung der Enden des Szintillators emittiert wird, den Smiley-Effekt verursachen. Gamma-Spektren in Koinzidenz mit ausgehenden 19N (bzw. 20N) wurden gewonnen und stimmen gut mit früheren Veröffentlichungen überein. Diese Spektren wurden dazu verwendet, die Übergänge des Projektilkerns in den Grundzustand und den ersten angeregten Zustand des Ejektilkerns zu identifizieren. Die Wirkungsquerschnitte des Coulombaufbruchs der Projektilkerne und die Anregungsenergiespektren beider Reaktionen wurden berechnet und separiert in Übergänge in den Grundzustand und die dominierenden Übergänge in den ersten angeregten Zustand. Um künftige Experimente an exotischen Kernen zu ermöglichen, wurden zusätzlich zwei Detektorkonzepte für NeuLAND (Nachfolger von LAND) untersucht. Mit minimal ionisierenden Elektronen mit Energien von 30MeV aus dem Elektronenbeschleuniger ELBE wurden die Zeitauflösungen und Detektionseffizienzen zum einen für einen MRPC (Multi-gap Resistive Plate Chamber) basierenden Neutronendetektor mit passiven Stahlkonverter und zum anderen für einen reinen szintillatorbasierenden Neutronendetektor studiert. Die ELBE-Daten zeigen gute Zeitauflösungen (σt,electron < 120ps) und Detektionseffizienzen (ǫelectron > 90%) für beide Systeme. Kleine MRPC-Prototypen wurden mit quasi-monochromatischen Neutronen mit einer Energie von 175MeV am TSL (The Svedberg Laboratory) in Uppsala bestrahlt. Dabei wurden Effizienzen von ǫMRPC,neutron = 1.0% gemessen. Es wird gezeigt, dass MRPCs mit passiven Stahlkonvertern als Neutronendetektoren bei Experimenten, bei denen eine geringere Multineutronenfähigkeit als für NeuLAND ausreichend ist, eingesetzt werden können
Williams, Robin James Richard. "The dynamics of active galactic nuclei." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318416.
Повний текст джерелаSembay, S. F. "Continuum radiation from Active Galactic Nuclei." Thesis, University of Southampton, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377792.
Повний текст джерелаWong, Yuen-lam. "Transient radiation emission from astrophysical jets." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39378512.
Повний текст джерелаWong, Yuen-lam, and 黃菀林. "Transient radiation emission from astrophysical jets." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39378512.
Повний текст джерелаChen, Guo-Xin. "Relativistic close coupling calculations for fundamental atomic processes in astrophysics." Columbus, Ohio : Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1078938510.
Повний текст джерелаTitle from first page of PDF file. Document formatted into pages; contains xxvi, 249 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Anil K. Pradhan, Dept. of Astronomy. Includes bibliographical references (p. 237-249).
Larsson, Josefin Boel Herta. "Black holes in high-energy astrophysics : active galactic nuclei and gamma-ray bursts." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612515.
Повний текст джерелаSanto, Marcelo Gimenez Del. "Estudo de reações nucleares de interesse astrofísico utilizando o método do cavalo de tróia." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-07042009-161106/.
Повний текст джерелаNuclear Astrophysics is the key to explain, among other things, the production of energy in stars, stellar evolution and the synthesis of chemical elements and isotopes in the Universe. In such cases, nuclear reactions are the main structure, where cross sections and reaction rates must be determined with reasonable accuracy in the laboratory. Because the extreme conditions found in stars, the understanding of nuclear processes that occur in their interiors have become a big challenge for theoretical and experimental nuclear physicists. In the last 40 years, physicists are getting the rates of these reactions but the uncertainty in these values are high due to difficulties found in the experimental cross section measurements at very low energies (Gamow peak region). Thus, only in some cases it is possible to measure directly the cross section and the behavior at low energies is usually extrapolated from the region of higher energy. To avoid the procedure of extrapolation, some indirect methods are being used successfully in recent years. In particular, the Trojan Horse Method gives the Astrophysics 7 S(E) factor of nuclear reactions involving charged particles at low energies without extrapolation and without electron screening effects. The reactions 10B(p,a)7Be and 11B(p,a)8Be are the main responsible for the burning process of boron inside F and G main sequence stars. The cross sections of these reactions have been obtained in previous direct experiments, but the data did not reach the Gamow peak and the behavior of the S(E) factor is then extrapolated from higher energies. In this work, we extract the S(E) factor for the reactions 10B(p,a)7Be and 11B(p,a)8Be through the indirect Trojan Horse Method (THM) applied to the three body reactions 2H(10B,a7Be)n e 2H(11B,a8Be)n without extrapolation. The astrophysical S(E)-factor for the 10B(p,a)7Be reaction was extracted by means of the THM and it is a factor 2 less in the Gamow peak if compared with previous direct studies. For the 11B(p,a)8Be reaction both a0 e a1 channels were studied by means of the THM and the astrophysical S(E)-factor extracted is in good agreement with direct previous studies.
Ouyed, Rachid. "Numerical simulations of astrophysical jets from Kerplerian accretion disks /." *McMaster only, 1996.
Знайти повний текст джерелаSun, Ai-Lei. "Active Galactic Nuclei Feedback and Galactic Out ows." Thesis, Princeton University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10167547.
Повний текст джерелаFeedback from active galactic nuclei (AGN) is thought to regulate the growth of supermassive black holes (SMBHs) and galaxies. The most direct evidence of AGN feedback is probably galactic outflows. This thesis addresses the link between SMBHs and their host galaxies from four different observational perspectives. First, I study the local correlation between black hole mass and the galactic halo potential (the MBH – Vc relation) based on Very Large Array (VLA) HI observations of galaxy rotation curves. Although there is a correlation, it is no tighter than the well-studied MBH – σ* relation between the black hole mass and the potential of the galactic bulge, indicating that physical processes, such as feedback, could link the evolution of the black hole to the baryons in the bulge. In what follows, I thus search for galactic outflows as direct evidence of AGN feedback. Second, I use the Atacama Large Millimeter Array (ALMA) to observe a luminous obscured AGN that hosts an ionized galactic outflow and find a compact but massive molecular outflow that can potentially quench the star formation in 10
6 years.The third study extends the sample of known ionized outflows with new Magellan long-slit observations of 12 luminous obscured AGN. I find that most luminous obscured AGN (Lbol > 1046 ergs s–1) host ionized outflows on 10 kpc scales, and the size of the outflow correlates strongly with the luminosity of the AGN. Lastly, to capitalize on the power of modern photometric surveys, I experiment with a new broadband imaging technique to study the morphology of AGN emission line regions and outflows. With images from the Sloan Digital Sky Survey (SDSS), this method successfully constructs images of the [OIII]λ5007 emission line and reveals hundreds of extended emission-line systems. When applied to current and future surveys, such as the Large Synoptic Survey Telescope (LSST), this technique could open a new parameter space for the study of AGN outflows. In summary, through multi-phase and multi-scale galactic outflows, AGN feedback can link the growth of SMBHs with the evolution of galaxies.
Ng, Shao-Chin Cindy. "Cosmological models with quintessence : dynamical properties and observational constraints." Title page, table of contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phn5758.pdf.
Повний текст джерелаBarioni, Adriana. "Estudo da interação de núcleos de massa A=8 com alvo de carbono e da reação de captura 8Li(p,)9Be de interesse astrofísico." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-13102009-133215/.
Повний текст джерелаThe measurements of the angular distributions for the elastic scatterings 12C(\'Li,\'Li) and 12C(8B,8B) reported in this work have been done in two laboratories. Those corresponding to the angular distributions for the elastic scattering 12C(8Li,8Li) were performed at two ene&ies, 20.6 MeV and 23.9 MeV, at the Pelletron Laboratory of the University of São Paulo. The *Li beam used in this laboratory had been produced in the RIBRASsystem. The measurements of angular distribution for the elastic scattering 12C(\'B,\'B) were performed at the Nuclear Structure Laboratory, at the University of Notre Dame, in the United States of America. The \'B beam was produced by the Twinsol system, at 25.8 MeV. The results obtained for total reaction cross section were included in a systematics\'together with other stable and exotic weakly bound nuclei and also with tightly bound ones, elastically scattered by 12C target. The data obtained from the literature were re-analised on the same framework of the data of this work. The reaction cross sections were obtained by fitting to the data, the cross secti\'ons calculated with the São Paulo potential. From the analysis one could conclude that no increase was observed in the total reaction cross section for the studied systems, indicating that effects, such as breakup, are not important for this system.
Packham, Christopher Charles. "Near infrared imaging and polarimetry of active galactic nuclei." Thesis, University of Hertfordshire, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338568.
Повний текст джерелаHanson, C. G. "The spectral shape and variability of active galactic nuclei." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374747.
Повний текст джерелаLomant, Susannah E. "Calculations of nuclear cross sections and astrophysical S-factors for reactions induced by protons and alpha particles on isotopes of copper." Virtual Press, 1999. http://liblink.bsu.edu/uhtbin/catkey/1137475.
Повний текст джерелаDepartment of Physics and Astronomy
Robinson, A. "A study of emission line variability in active galactic nuclei." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356433.
Повний текст джерела