Littérature scientifique sur le sujet « Μ-Beams »
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Articles de revues sur le sujet "Μ-Beams"
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Renga, Francesco, Gianluca Cavoto, Angela Papa, Emanuele Ripiccini et Cecilia Voena. « Experimental Limiting Factors for the Search of μ→eγ at Future Facilities ». Universe 5, no 1 (15 janvier 2019) : 27. http://dx.doi.org/10.3390/universe5010027.
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The search for the Lepton Flavor Violating decay μ → e γ exploits the most intense continuous muon beams, which can currently deliver ∼ 10 8 muons per second. In the next decade, accelerator upgrades are expected in various facilities, making it feasible to have continuous beams with an intensity of 10 9 or even 10 10 muons per second. We investigate the experimental limiting factors that will define the ultimate performances, and hence the sensitivity, in the search for μ → e γ with a continuous beam at these extremely high rates. We then consider some conceptual detector designs and evaluate the corresponding sensitivity as a function of the beam intensity.
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Bogomyagkov, Anton, Vladimir Druzhinin, Eugene Levichev, Alexander Milstein et Sergej Sinyatkin. « Low-energy electron-positron collider to search and study (μ+μ−) bound state ». EPJ Web of Conferences 181 (2018) : 01032. http://dx.doi.org/10.1051/epjconf/201818101032.
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We discuss a low energy e+e− collider for production of the not yet observed (μ+μ−) bound system (dimuonium). Collider with large crossing angle for e+e− beams intersection produces dimuonium with non-zero momentum; therefore, its decay point is shifted from the beam collision area providing effective suppression of the elastic e+e− scattering background. The experimental constraints define subsequent collider specifications. We show preliminary layout of the accelerator and obtained main parameters. High luminosity in chosen beam energy range allows to study π± and η-mesons.
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MORASSI, ANTONIO, GEN NAKAMURA, KENJI SHIROTA et MOURAD SINI. « A variational approach for an inverse dynamical problem for composite beams ». European Journal of Applied Mathematics 18, no 1 (février 2007) : 21–55. http://dx.doi.org/10.1017/s0956792507006833.
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This paper deals with a problem of nondestructive testing for a composite system formed by the connection of a steel beam and a reinforced concrete beam. The small vibrations of the composite beam are described by a differential system where a coupling takes place between longitudinal and bending motions. The motion is governed in space by two second order and two fourth order differential operators, which are coupled in the lower order terms by the shearing,k, and axial, μ, stiffness coefficients of the connection. The coefficientskand μ define the mechanical model of the connection between the steel beam and the concrete beam and contain direct information on the integrity of the system. In this paper we study the inverse problem of determiningkand μ by mixed data. The inverse problem is transformed to a variational problem for a cost function which includes boundary measurements of Neumann data and also some interior measurements. By computing the Gateaux derivatives of the functional, an algorithm based on the projected gradient method is proposed for identifying the unknown coefficients. The results of some numerical simulations on real steel-concrete beams are presented and discussed.
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Palladino, Vittorio. « Neutrino beams : μ decay vs. π decay ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 451, no 1 (août 2000) : 141–53. http://dx.doi.org/10.1016/s0168-9002(00)00553-2.
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Kohl, Michael. « Lepton Universality Test with MUSE at PSI ». Journal of Physics : Conference Series 2391, no 1 (1 décembre 2022) : 012015. http://dx.doi.org/10.1088/1742-6596/2391/1/012015.
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Abstract Lepton universality (LU) typically refers to the lepton coupling, which is considered to be the same for e, μ, and τ leptons, if the interaction is electroweak according to the Standard Model, and it is hence a compelling probe for New Physics. The same principle of universal electroweak lepton interaction leads to the expectation that lepton scattering yields are equal for e and μ beams under the same kinematic condition. The mere mass difference between e and μ affects kinematic quantities (such as the relation between scattering angle and Q 2), and the lepton mass dependence of elastic cross sections for leptons scattered from structured and pointlike objects are taken into account. By comparing e +, e −, μ +, and μ − scattering yields, two-photon exchange (TPE) effects, universal or not, can be separated from the general LU test of the e/μ yield ratio. With its separable mixed beams of e +/μ + and e −/μ −, respectively, the MUSE experiment at PSI is not only designed to measure the proton charge radius with four lepton species, but is also uniquely suited to probe TPE and LU, while benefitting from partial cancellations of certain shared systematics. An overview will be given of the MUSE experiment, the sensitivity, and the present status.
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Fan, Hua, Meguya Ryu, Reo Honda, Junko Morikawa, Zhen-Ze Li, Lei Wang, Jovan Maksimovic, Saulius Juodkazis, Qi-Dai Chen et Hong-Bo Sun. « Laser-Inscribed Stress-Induced Birefringence of Sapphire ». Nanomaterials 9, no 10 (3 octobre 2019) : 1414. http://dx.doi.org/10.3390/nano9101414.
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Birefringence of 3 × 10 - 3 is demonstrated inside cross-sectional regions of 100 μ m, inscribed by axially stretched Bessel-beam-like fs-laser pulses along the c-axis inside sapphire. A high birefringence and retardance of λ / 4 at mid-visible spectral range (green) can be achieved using stretched beams with axial extension of 30–40 μ m. Chosen conditions of laser-writing ensure that there are no formations of self-organized nano-gratings. This method can be adopted for creation of polarization optical elements and fabrication of spatially varying birefringent patterns for optical vortex generation.
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Bogacz, S. A., et D. B. Cline. « A μ+μ- Quantum Collider using Novel Crystal-Based Accelerator Components ». International Journal of Modern Physics A 12, no 18 (20 juillet 1997) : 3181–92. http://dx.doi.org/10.1142/s0217751x97001675.
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We outline a concept of a 250 × 250 GeV μ+ μ- collider that uses bent crystals for beam confinement and steering instead of conventional magnets. The collider ring is based on a novel bending-focusing crystal cell. Beam optics of the proposed model cell has all the features of the alterating gradient FODO cell. Furthermore, alternating (horizontal-vertical) focusing provides unique betatron phase stability in both planes, while bending of particle trajectories due to crystal curvature is fully achromatic. We also explore the ionization energy loss of channeling muons interacting with the electron gas in a crystal channel as a possible cooling mechanism. Finally, a use of low Z binary crystals (such as LiF) for final focus at the interaction point is proposed. Bringing the μ+μ- into collision inside a crystal channel results in quantum confinement at the collision point. For such a collider the number of required μ± may be very low (~108μ per pulse), so that this collider has few problems from μ → e backgrounds or heating, which is a virtue of paramount importance. A low intensity hadronic μ± source (p + A → π → μ) can be utilized provided that an effective method of fast muon cooling is used. For example, the use of frictional cooling for low energy μ± beams could initially reduce the longitudinal phase–space, before the final transverse cooling is applied. Here, we outline such a "crystal cooler" that explores ionization energy loss in the ultrastrong focusing environment of a crystal channel. Employing all the above-mentioned novel crystal-based accelerator components, a possible luminosity of about 1032 cm-2 sec-1, is estimated for the proposed quantum collider. We also discuss a list of problems one needs to solve in order to make such a collider a real possibility.
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Li, Xiao-Jun, Yan-Cheng Ye, Yan-Shan Zhang et Jia-Ming Wu. « Empirical modeling of the percent depth dose for megavoltage photon beams ». PLOS ONE 17, no 1 (6 janvier 2022) : e0261042. http://dx.doi.org/10.1371/journal.pone.0261042.
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Introduction This study presents an empirical method to model the high-energy photon beam percent depth dose (PDD) curve by using the home-generated buildup function and tail function (buildup-tail function) in radiation therapy. The modeling parameters n and μ of buildup-tail function can be used to characterize the Collimator Scatter Factor (Sc) either in a square field or in the different individual upper jaw and lower jaw setting separately for individual monitor unit check. Methods and materials The PDD curves for four high-energy photon beams were modeled by the buildup and tail function in this study. The buildup function was a quadratic function in the form of dd2+n with the main parameter of d (depth in water) and n, while the tail function was in the form of e−μd and was composed by an exponential function with the main parameter of d and μ. The PDD was the product of buildup and tail function, PDD = dd2+n·e−μd. The PDD of four-photon energies was characterized by the buildup-tail function by adjusting the parameters n and μ. The Sc of 6 MV and 10 MV can then be expressed simply by the modeling parameters n and μ. Results The main parameters n increases in buildup-tail function when photon energy increased. The physical meaning of the parameter n expresses the beam hardening of photon energy in PDD. The fitting results of parameters n in the buildup function are 0.17, 0.208, 0.495, 1.2 of four-photon energies, 4 MV, 6 MV, 10 MV, 18 MV, respectively. The parameter μ can be treated as attenuation coefficient in tail function and decreases when photon energy increased. The fitting results of parameters μ in the tail function are 0.065, 0.0515, 0.0458, 0.0422 of four-photon energies, 4 MV, 6 MV, 10 MV, 18 MV, respectively. The values of n and μ obtained from the fitted buildup-tail function were applied into an analytical formula of Sc = nE(S)0.63μE to get the collimator to scatter factor Sc for 6 and 10 MV photon beam, while nE, μE, S denotes n, μ at photon energy E of field size S, respectively. The calculated Sc were compared with the measured data and showed agreement at different field sizes to within ±1.5%. Conclusions We proposed a model incorporating a two-parameter formula which can improve the fitting accuracy to be better than 1.5% maximum error for describing the PDD in different photon energies used in clinical setting. This model can be used to parameterize the Sc factors for some clinical requirements. The modeling parameters n and μ can be used to predict the Sc in either square field or individual jaws opening asymmetrically for treatment monitor unit double-check in dose calculation. The technique developed in this study can also be used for systematic or random errors in the QA program, thus improves the clinical dose computation accuracy for patient treatment.
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Namdeo, Jitendra, S. K. Dubey et Lobzang Dorji. « Dynamic Analysis of Isotropic Homogeneous Beams Using the Method of Initial Functions and Comparison with Classical Beam Theories and FEM ». Complexity 2023 (9 décembre 2023) : 1–18. http://dx.doi.org/10.1155/2023/6636975.
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The main aim of this study is the dynamic analysis of isotropic homogeneous beams using the method of initial functions (MIFs) and comparison with classical beam theories and FEM. Also, this research employs the state space methodology, with a special emphasis on isotropy, to analyse simply supported beam systems. A mathematical model for the dynamic response of beams is constructed using the method of initial functions. The novelty of this study lies in its approach to dynamic analysis, where isotropic homogeneous beams are explored without making assumptions, thus ensuring increased precision using the method of initial functions. Importantly, the approach remains free from restrictive assumptions and relies solely on mathematical formulations, yielding results superior to classical beam theories such as Euler–Bernoulli, Timoshenko, and Rayleigh beam theories. In this work, the application of MIFs of various orders (4th, 6th, 8th, and 10th) to calculate natural frequencies is explored, enabling a thorough examination of the beam’s dynamic characteristics. In addition, parameters such as normal stresses, shear stresses, and deflections in different directions are considered to provide a comprehensive understanding of beam behaviour. To validate the findings, a detailed comparison with a finite element method (FEM) is conducted, achieving excellent agreement between the analytical results and FEM solutions. Furthermore, the influence of Poisson’s ratio (μ) on natural frequencies is investigated by varying its value from 0.18 to 0.30. The research also explores the deviation of plane stress values of the beam section from those estimated using the FEM for the corresponding components.
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Curatolo, Camilla, et Luca Serafini. « Electrons and X-rays to Muon Pairs (EXMP) ». Applied Sciences 12, no 6 (19 mars 2022) : 3149. http://dx.doi.org/10.3390/app12063149.
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One of the challenges of future muon colliders involves the production of muon beams carrying high phase space densities. In particular, the muon beam normalised transverse emittance is a relevant figure of merit used to meet luminosity requests. A typical issue impacting the achieved transverse emittance in muon collider schemes, thus far considered, is the phase space dilution caused by the Coulomb interaction of primary particles propagating into the target where muons were generated. In this study, we present a new scheme(named electrons and X-rays to muon pairs) for muon beam generation occurring in a vacuum via interactions of electron and photon beams. Setting the center of mass energy at about twice the threshold (i.e., around 350 MeV), the normalised emittance of the muon beam generated via muon pair production reaction (e−+γ→e−+μ++μ−) is largely independent on the emittance of the colliding electron beam and is set basically by the excess of transverse momentum in the muon pair creation. In absence of any other mechanism for emittance dilution, the resulting muon beam, with energy in the range of a few tens of GeV, is characterised by an ultra-low normalised transverse RMS emittance of a few nm rad, corresponding to a geometrical emittance below 10 π pm rad. This opens up the way to a new muon collider paradigm based on muon sources conceived with primary colliding beams delivered by 100 GeV-class energy recovery LINACs interacting with hard-X ray free electron lasers. The challenge is to achieve the requested luminosity of the muon collider adopting a strategy of low muon fluxes/currents combined to ultra-low emittances, to largely reduce the levels of muon beam-induced backgrounds.
Thèses sur le sujet "Μ-Beams"
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Elias, Victory. « An approach based on the µ-vibration concept contributes to the characterization and objective analysis of physiological fluids ». Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2023. http://www.theses.fr/2023UPHF0044.
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Dans un monde en constante évolution technologique, les capteurs micro électromécaniques (MEMS) prennent une place prépondérante dans divers domaines tels que la biomédecine, l’industrie aérospatiale et les technologies de l’information et de la communication. Au cœur de cette révolution, les micro-poutres cantilever offrent une sensibilité exceptionnelle, permettant la détection de variations physiques infimes. Cette thèse se consacre à la conception d’une nouvelle architecture de capteurmicro-poutres cantilever, visant à optimiser leur sensibilité et à étendre leurs applications pratiques. Le travail entrepris s’est focalisé sur l’élaboration d’un modèle théorique et la validation expérimentale d’une structure cantilever plongée dans un fluide newtonien incompressible, caractérisée par des dimensions précises et une conception innovante. La partie numérique de l’étude a permis de tester la sensibilité de l’architecture proposée face à des charges externes, tandis que les expériences pratiques ont impliqué la fabrication et l’assemblage minutieux des composants du capteur, y compris l’intégration de matériaux piézoélectriques. L’innovation ne s’arrête pas là ; l’avenir envisagel’incorporation de revêtements biochimiques pour la détection spécifique et l’utilisation de techniques microfluidiques pour une analyse en temps réel, marquant ainsi un pas en avant significatif dans la recherche et le développement des MEMS. La quête de sensibilité accrue dans les capteurs MEMS cantilever nous a menés à la conception et à l’élaboration d’une structure optimisée, explorée à travers ce travail de thèse. L’intégration réussie de l’architecture exponentielle dans la micro-poutre cantilever et l’application de techniques de pointe en fabrication et en tests numériques représentent des avancées significatives dans la recherche en MEMS. Les résultats obtenus ouvrent des perspectives fascinantes pour l’amélioration et l’application de ces capteurs dans des environnements complexes. Les futurs travaux, incluant l’application de revêtements biochimiques et le développement de chambres microfluidiques, promettent d’étendre encore davantage le champ d’application et d’efficacité de ces dispositifs sensibles.En résumé, cette thèse contribue à l’avancement de la science et de la technologie des capteurs MEMS, en proposant des solutions innovantes pour les défis actuels et futurs dans les domaines nécessitant une détection précise et une sensibilité accrue. Elle pose ainsi les bases pour les développements futurs qui bénéficieront sans aucun doute à de nombreuses disciplines scientifiques et applications industriellesIn a world of continuous technological evolution, micro-electromechanical system (MEMS) sensors are becoming increasingly prominent in various fields such as biomedicine, the aerospace industry,and information and communication technologies. At the heart of this revolution, cantilever microbeams provide exceptional sensitivity, allowing the detection of minute physical variations. This thesis is dedicated to the design of a new cantilever microbeam sensor architecture aimed at optimizing their sensitivity and expanding their practical applications. The work undertaken focused on developing a theoretical model and experimental validation of a cantilever structure immersed in an incompressible Newtonian fluid, characterized by precise dimensions and an innovative design. The numerical part of the study allowed for testing the sensitivity of the proposed architecture against external loads, while the practical experiments involved the meticulous fabrication and assembly of the sensor components, including the integration of piezoelectric materials. Innovation does not stop here; the future envisions the incorporation of biochemical coatings for specific detection and the use of microfluidic techniques for real-time analysis, thereby marking a significant step forward in MEMS research and development. The quest for increased sensitivity in cantilever MEMS sensors has led us to the design and creation of an optimized structure, explored through this thesis work. The successful integration of the exponential architecture into the cantilever microbeam and the application of cutting-edge techniques in fabrication and numerical testing represent significant advancements in MEMS research. The results obtained open exciting prospects for the improvement and application of these sensors in complex environments. Future work, including the applicationof biochemical coatings and the development of microfluidic chambers, promises to further extend the scope of application and effectiveness of these sensitive devices. In summary, this thesis contributes to the advancement of science and technology in MEMS sensors, proposing innovative solutions for current and future challenges in fields requiring precise detection and increased sensitivity. It thus lays the groundwork for future developments that will undoubtedly benefit many scientific disciplines and industrial applications
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Noun, Manale. « Interaction agrégats-surface. Spectrométrie de masse par temps de vol et application analytique à des études sur des médicaments et sur la météorite Paris ». Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00906791.
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Le Lebanese Atomic Energy Commission (LAEC) poursuit un programme de développement des techniques analytiques pour compléter l'analyse par faisceau d'ions (IBA). Il a décidé de s'équiper d'un spectromètre de masse couplée à l'imagerie 2D puis récemment 3D avec l'acquisition d'un spectromètre de masse IONTOF V™ équipé de deux colonnes ioniques délivrant des faisceaux d'agrégats de bismuth et d'argon. Dans ce cadre, mon sujet de thèse a porté sur l'optimisation de l'instrument nouvellement acquis pour l'analyse d'échantillons contenant des composés organiques. Les premiers sujets de recherche sont la mise au point du protocole d'analyse quantitative de médicaments en utilisant la technique " cluster-SIMS-imaging " et l'analyse de la météorite Paris pour localiser la matière organique et déterminer sa composition. Dans les deux cas une approche multi-technique a été utilisée : IBA au LAEC, µ-Raman et µ-IR autour des équipements de Soleil et µPIXE réalisée auprès de l'accélérateur AGLAE (Centre de recherche et de restauration des musées de France, C2RMF).L'analyse de médicaments a été initiée au Liban en collaboration avec un fabricant local de produits pharmaceutiques (Mediphar Laboratories) dans le but d'établir de nouveaux procédés de contrôle qualité de produits finis. Mon étude a montré la complexité du dosage de médicament due à la présence de plusieurs molécules actives (Principe Actif, PA) et de substances organiques et minérales inactives (excipients) mélangées dans des conditions secrètes. Les effets de matrice sont dominants et modifient l'émission ionique conduisant à des erreurs systématiques importantes. Cette complexité a été analysée avec l'étude du Fludinium™ possédant deux PAs. Les résultats de cette étude ont permis d'obtenir la première courbe d'étalonnage du rapport des deux PAs et de quantifier ceux-ci dans les conditions du médicament commercial. Le protocole pour effectuer cette courbe d'étalonnage et les contrôles " qualité " ont été déterminés. Ceux-ci incorporeront une analyse en profil pour contrôler l'homogénéité des échantillons et l'obtention d'étalons produits par le fabricant en suivant ses processus de fabrication. En effet, les expériences ont montré que la réalisation du médicament en laboratoire à partir de ses éléments (PAs et excipients) ne donnait pas la même réponse ionique que le médicament commercial. L'analyse de la météorite Paris a été initiée par une collaboration avec une équipe de l'Institut d'Astrophysique Spatial d'Orsay impliquée dans l'exobiologie et la recherche des premières molécules pré-biotiques dans des échantillons extraterrestres. Le but des recherches est de caractériser la matière organique représentant quelques pourcents en poids dans une matrice minérale complexe, sans utiliser des méthodes chimiques pouvant induire une modification de ces molécules. Cette étude a démontré l'intérêt de l'approche multi-technique centrée autour de la spectrométrie de masse couplée à l'imagerie ionique pour déterminer les éléments principaux de la matrice minérale et organique. L'analyse par µPIXE avec une cartographie micrométrique a permis d'attribuer les distributions d'ions moléculaires et agrégats des spectres de masse aux différents composés minéraux. Ces attributions se poursuivent avec la constitution d'une base de données de spectres de référence. La composante organique a été extraite et les premières hypothèses de composition ont été envisagées autour des HAPs (Hydrocarbure Aromatique Polycyclique), MOI (Matière Organique Insoluble) et analogues de carbone amorphe produits par irradiation UV de glaces dont les compositions en gaz représentent différentes hypothèses pour les nuages interstellaires. Les protocoles d'analyses multi-techniques établis (incorporant un suivi de l'échantillon par spectrométrie de masse et imagerie ionique) permettent le démarrage d'analyse d'autres échantillons extra-terrestres collectés sur terre ou dans l'espace.
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Cheng, I.-Ming, et 鄭宜明. « Failure Analysis of TFT-LCD Source Driver IC with E-Beam Prober linking to VLSI Tester (SC-μ) ». Thesis, 2002. http://ndltd.ncl.edu.tw/handle/21766624871647044170.
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碩士國立清華大學
電子工程研究所
91
A new system of failure analysis for TFT-LCD Source Driver IC is presented. This system is suitable to two package types (TCP and QTCP) of TFT-LCD Source Driver IC. This system consists of a high success rate (94%) de-capsulate technique, a new fixture between device and E-Beam Prober and a powerful/flexible test program. All of above make failure analysis of TFT-LCD Source Driver IC by E-Beam prober linking to VLSI Tester (SC-μ) being successful and practicable. In addition to failure analysis with E-Beam Prober, these new techniques are also useful to other failure analysis tools such as internal probing at probe-station, Emission Microscope for Multi-layer Inspection (EMMI), Optical Beam Induced Resistance Change (OBIRCH), Liquid Crystal (LC), etc. Besides, an Open-Loop method for OP (operation amplifier) is also presented which makes OP analysis become more effective. Hspice simulation is also introduced to help failure analysis in OP. With this system, for TFT-LCD Source Driver IC, failure analysis success rate is promoted and failure analysis cycle time is shortened successfully and effectively.
Chapitres de livres sur le sujet "Μ-Beams"
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Nagamine, K. « Slow μ + and μ - Beam Production and the Next Generation of Muon Science ». Dans Springer Proceedings in Physics, 55–60. Berlin, Heidelberg : Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-76370-0_4.
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Yamamoto, Naoki. « Development of μ-Fluorescent and Diffracted X-Ray Spectrometer with a Fine Focused X-Ray Beam and Its Application for Ulsi Microanalysis ». Dans Advances in X-Ray Analysis, 155–64. Boston, MA : Springer US, 1997. http://dx.doi.org/10.1007/978-1-4615-5377-9_19.
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Gastmans, R., et Tai Tsun Wu. « Double Bremsstrahlung ». Dans The Ubiquitous Photon, 65–78. Oxford University PressOxford, 1990. http://dx.doi.org/10.1093/oso/9780198520436.003.0006.
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Abstract Double bremsstrahlung processes in QED, such as e+e- → γ γ γ γ, e+e- → μ+ μ- γ γ ande+e- → e+e- γ γ, are of interest for several reasons. They have all been observed in experiments and provide high energy QED tests of order α4 [28]. The agreement between theory and experiment for the process e+ e-→ μ+ μ- γ γ has been widely used to set lower limits on the mass of the excited muon. This was done both at PEP [29] at GeV and at PETRA [30] at higher energies. It is also not inconceivable that the effects of this process have to be taken into account if the accuracy of the charge asymmetry measurements in e+ e-→ μ+ μ- continues to increase. Finally, the process e+ e-→ μ+ μ- γ γgives an a4 contribution to small angle Bhabha scattering, which is generally used to determine the beam luminosity of e+ecolliders [28].
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« Beam dynamics problems of the muon collaboration : ν-factories and μ+ -μ- colliders ». Dans Computational Accelerator Physics 2003, 251–58. CRC Press, 2005. http://dx.doi.org/10.1201/9781482269086-32.
Texte intégralActes de conférences sur le sujet "Μ-Beams"
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Sarkar, Dipta, Samuel W. Oxandale, Tyler J. Hieber, M. G. Baboly et Zayd C. Leseman. « Thermal Property Measurements of Si µ-Cantilever Beams Using the Suspended Thermoreflectance Technique ». Dans ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11690.
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Abstract Thermoreflectance is a common technique to measure thermal properties of micro/nano devices. Most thermoreflectance techniques use a pump-probe scheme with lasers to heat the sample and analyze the temperature. The limiting characteristics of most of these techniques are that they can probe the temperature at only one spot on the sample, assume a value for either heat capacity or thermal conductivity to find the other, and require a semi-infinite substrate. In this paper, a new technique is described, the Suspended ThermoReflectance (STR) technique, which allows measurement of thermal conductivity by probing multiple points along the length of a suspended micro/nano-scale sample. This technique involves a pump laser for heating the tip of a suspended μ-cantilever Si beam and a probe laser to scan the temperature along the μ-cantilever’s length. Thermal conductivity is obtained by applying the heat diffusion equation for the temperature gradient along the beam length. 2.9 μm thick Si μ-cantilever samples are tested over a range of temperatures from 20–300K. It is found that thermal conductivity of the silicon varies from 28 W/mK to 80 W/mK.
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Lax, B., R. M. Marino et R. S. Eng. « Multisection Broadband Modulator ». Dans Coherent Laser Radar. Washington, D.C. : Optica Publishing Group, 1987. http://dx.doi.org/10.1364/clr.1987.mb7.
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The single sideband (SSB) modulator described by Carter and Haus1 has limitations over a broadband frequencies. To maximize the output of their device with CdTe in a square waveguide, the beat frequency of the laser and the sideband are phase matched with the microwaves. The dimension of the guide a is determined by satisfying the equation where β1,2 are the propagation constants of the sideband and the laser beams respectively in CdTe at 10.6 μm, ϵ =7.2, ϵ μ =10.4. Equation(1) is satisfied for a =5.2 mm and f μ =16 GHz. When the microwave frequency deviates from this value , then the output is reduced according to the solution of the coupled-mode equations.1
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Law, C. T., et A. E. Kaplan. « Instability of dispersive counterpropagating waves in a Kerr nonlinear medium ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.wm4.
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The temporal instability of counterpropagating beams in a Kerr nonlinear medium due to relaxation is well exploited.1 We demonstrate that another even more fundamental physical parameter, linear dispersion, can lead to instability. We investigate instability in the simplest eigenarrangement2 with the polarization of two counterpropagating beams being linear and parallel to each other. The dynamic equations for forward and backward propagating envelopes E1(z, t) and E2(z, t) are i [ ( − 1 ) j − 1 ∂ E j / ∂ z + v g − 1 ∂ E j / ∂ t ] − μ ∂ 2 E j / 2 ∂ t 2 = − χ 2 k 0 ( 2 I 3 − j + I j ) E j / 2 , where j = 1, 2 and I j = |E j |2 is the intensity of the respective wave, μ = ∂2k/∂ω2 is a linear dispersion parameter, χ2 is third-order susceptibility giving rise to nonlinear refractive index, and v g is the (linear) group velocity. For large dispersion, unstable modes with lowest frequencies are excited first. The threshold intensity I required to excite these unstable modes diminishes as dispersion increases. In the case of I1 = I2= I and sufficiently large parameter p = χ2k0/L/2, this threshold intensity I is determined by p ≃ log ( μ v g 2 / 2 L ) , where L is the total length of the nonlinear medium. More modes are excited when the intensity exceeds this threshold, and their combinations may yield chaotic behavior. The mechanism of the resulting instability can be explained in terms of positive distributed feedback provided by the nonlinear index grating in the situation that the phase speed of small perturbations with slightly different frequencies is altered by linear dispersion.
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Shi, Qiuhu, et Ya-wen Yang. « Optical bistability in semiconductor CdHgTe etalon ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.thmm50.
Texte intégralRésumé :
We have observed bistability of the n-type Cd x Hg1− x Te in Auger-dominated in the following conditions: the input probe beam, obtained by splitting the CO2 laser with a ZnSe splitter, was incident upon the CdHgTe detector 1. The output probe beam, passing through the Fabry-Perot etalon, was detected by the CdHgTe detector 2. All beams were chopped using a mechanical chopper with a tunable mark/space ratio between 20:1 at a high speed synchronous motor. The signals of the incident and transmission intensity synchronously detected by using the CdHgTe detectors at 77 K were displayed on an oscilloscope. Our specimen was n-type Cd x Hg1− x Te (x = 0.225) at 77 K, the intrinsic carrier concentration n = 9.8 × 1014 cm-3, the mobility μ = 3.15 × 104 (cm2/V sec). The absorption coefficient α = 72 cm was polished plane parallel to form an etalon 215 μm thick, the reflectivities of which are R F = R B = R = 32%. In our experiment, the incident intensity I is 750 W/cm2 and both the laser mode and power stability met the standards.
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Hu, X. F., et M. C. Downer. « Femtosecond ellipsometric study of nonequilibrium carrier dynamics in Si1-xGex ». Dans International Conference on Ultrafast Phenomena. Washington, D.C. : Optica Publishing Group, 1994. http://dx.doi.org/10.1364/up.1994.tua.4.
Texte intégralRésumé :
In III-V semiconductors, comparison of femtosecond time scale optical measurements1 with microscopic carrier dynamic theory2 has become direct and quantitative. In Column IV semiconductors, on the other hand, quantitative experiment-theory comparison has been achieved only on a picosecond time scale.3 This paper presents a systematic study of the fs.-time-resolved ellipsometric response of epitaxial Si1.xGex (0≤x≤l) alloys as a first step in measuring and modelling subpicosecond bulk carrier dynamics. Pump and probe beams were derived from either an unamplified CPM laser4 (620 nm wavelength) or an unamplified KLM laser(800nm + 400nm second harmonic). The time-dependent optical response is related to free carrier density Neh(t), reduced effective mass μ*(t) via a time-varying Drude-Lorentz dielectric function:
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Almandeel, Ali, Abdulaziz Aladwani et Hessein Ali. « Synthesis of Defect-Free Peaucellier Mechanism and Potential Implications for Energy Harvesting ». Dans ASME 2021 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/detc2021-69279.
Texte intégralRésumé :
Abstract Cantilevered beams with piezoceramic layers are typically used to generate electrical energy; hence, a base excitation on a harvester is required. This work investigates the use of a link-type mechanism called the Peaucellier mechanism to actuate piezoelectric energy harvesters. The Peaucellier mechanism is known to trace an exact straight line, providing harmonic motion, which is exploited here for exciting a bimorph piezoelectric cantilever beam. To generate the required base excitation, a function generation synthesis methodology for designing a defect-free Peaucellier mechanism driven by a dyad (PMD) is proposed, in addition to an example being provided to confirm the efficacy of the method. The harmonic motion involves two design variables (frequency and amplitude) which are key parameters and can be tuned to generate the required electrical power. It was determined that PMD could excite the energy harvester, generating an electrical power of approximately 4.52 μ W at low frequency. The synthesis generated a mean absolute error of 0.061 m/s2 confirming an excellent match between the points of the input-output and desired acceleration. The results confirm that the Peaucellier mechanism is suitable for the actuation of energy harvesters where parasitic power harvesting is required in different practical applications, including robotics and stationary machines.
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Ciuffini, Francesco. « Latest Advances In Powder Metallurgy Characterization At European Synchrotron Radiation Facility (ESRF) ». Dans Euro Powder Metallurgy 2023 Congress & Exhibition. EPMA, 2023. http://dx.doi.org/10.59499/ep235763648.
Texte intégralRésumé :
In 2021 was completed the upgrade of the European Synchrotron Radiation Facility ESRF – EBS (Extremely Brilliant Source), becoming the first new generation of high-energy synchrotron, increasing brilliance and coherence of X-ray beams by a factor of 100 compared to present-day light sources. The highlights of the research activities in powder metallurgy made in these 2 years would be presented: the measurement of stress relief given by heat treatment on the residual stresses of an additive manufactured AISI 316L stainless steel arch structure (part of EU-funded EASI-STRESS project); a synchrotron μ-tomographic morphological description of additively manufactured open porous structures made by Laser-based Powder Bed Fusion (L-PBF), to characterize attached spherical particles on the surface of functional structures; a study about the solidification of a new Al-4Mn-3Ni-2Cu-1Zr alloy, designed for L-PBF, developing a new strategy for alloy design in high-strength aluminum alloys for powder metallurgy.
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Green, Michael A. « Some options for the muon collider capture and decay solenoids ». Dans The 9th advanced ICFA beam dynamics workshop : Beam dynamics and technology issues for μ+μ− colliders. American Institute of Physics, 1996. http://dx.doi.org/10.1063/1.50895.
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Vsevolozhskaya, Tatiana A. « Kinetics of ionization cooling of muons ». Dans The 9th advanced ICFA beam dynamics workshop : Beam dynamics and technology issues for μ+μ− colliders. American Institute of Physics, 1996. http://dx.doi.org/10.1063/1.50894.
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Turner, William C. « An induction linac approach to phase rotation of a muon bunch in the production region of a μ+−μ− Collider ». Dans The 9th advanced ICFA beam dynamics workshop : Beam dynamics and technology issues for μ+μ− colliders. American Institute of Physics, 1996. http://dx.doi.org/10.1063/1.50896.
Texte intégralRapports d'organisations sur le sujet "Μ-Beams"
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Linden, Steven K. Measurement of the νμ Charged Current π+ to Quasi-Elastic Cross Section Ratio on Mineral Oil in a 0.8 GeV Neutrino Beam. Office of Scientific and Technical Information (OSTI), janvier 2011. http://dx.doi.org/10.2172/1018733.
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Huang, Ying-Chiang. The search for neutrino oscillations in the appearance mode ημ → ηe for neutrino energies near the muon threshold [Search for neutrino oscillations using a liquid scintillator detector in a muon neutrino beam at LAMPF]. Office of Scientific and Technical Information (OSTI), décembre 1986. http://dx.doi.org/10.2172/6236640.
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