Articles de revues : « Μ-Beams »

1

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, n^o 1 (15 janvier 2019) : 27. http://dx.doi.org/10.3390/universe5010027.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

2

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

3

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, n^o 1 (février 2007) : 21–55. http://dx.doi.org/10.1017/s0956792507006833.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

4

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, n^o 1 (août 2000) : 141–53. http://dx.doi.org/10.1016/s0168-9002(00)00553-2.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

5

Kohl, Michael. « Lepton Universality Test with MUSE at PSI ». Journal of Physics : Conference Series 2391, n^o 1 (1 décembre 2022) : 012015. http://dx.doi.org/10.1088/1742-6596/2391/1/012015.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

6

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, n^o 10 (3 octobre 2019) : 1414. http://dx.doi.org/10.3390/nano9101414.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

7

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, n^o 18 (20 juillet 1997) : 3181–92. http://dx.doi.org/10.1142/s0217751x97001675.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

8

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, n^o 1 (6 janvier 2022) : e0261042. http://dx.doi.org/10.1371/journal.pone.0261042.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

9

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.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Curatolo, Camilla, et Luca Serafini. « Electrons and X-rays to Muon Pairs (EXMP) ». Applied Sciences 12, n^o 6 (19 mars 2022) : 3149. http://dx.doi.org/10.3390/app12063149.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

11

THOMPSON, M. C., H. BADAKOV, J. B. ROSENZWEIG, G. TRAVISH, H. EDWARDS, R. FLILLER, G. M. KAZAKEVICH et al. « RESULTS FROM THE UCLA/FNPL UNDERDENSE PLASMA LENS EXPERIMENT ». International Journal of Modern Physics A 22, n^o 22 (10 septembre 2007) : 3979–87. http://dx.doi.org/10.1142/s0217751x0703755x.

Texte intégral

Résumé :

A gaussian underdense plasma lens with peak density 5 × 1012 cm −3 and a full width half maximum (FWHM) length of 2.2 cm has been used to focus a relativistic electron beam. This plasma lens is equivalent in strength to a quadrupole magnet with a 150 T/m field gradient. The lens focused a 15 MeV, 16 nC electron beam with initial dimensions σx,y ≈ 650 μ m and σz ≈ 6.5 mm onto an optical transition radiation (OTR) screen ~2 cm downstream of the lens. The average transverse area of the plasma focused electron beam was typically demagnified by a factor of 23. The evolution of the beam envelope in the area near the beam waist was measured for both round beams and asymmetric beams with x:y aspect ratios as large as 1:5. The light from the OTR screen in the round beam case was also imaged into a streak camera in order to directly measure the correlation between z and σr within the beam.

Styles APA, Harvard, Vancouver, ISO, etc.

12

BOGACZ, S. A., et D. B. CLINE. « RECENT DEVELOPMENTS IN μ+μ− COLLIDERS ». International Journal of Modern Physics A 11, n^o 15 (20 juin 1996) : 2613–21. http://dx.doi.org/10.1142/s0217751x96001255.

Texte intégral

Résumé :

New developments in crystal-based accelerator techniques for future μ+μ− colliders are outlined in the context of promising μ+μ− physics opportunities opening in the 250×250 GeV energy range (which will be discussed briefly). One of the novel schemes involves laser-driven high gradient (GeV/m) crystal acceleration combined with an effective crystal “cooler,” based on a stimulated radiation damping in a strain-modulated silicon crystal. The ultrastrong focusing environment of a crystal channel would provide effective transverse cooling without substantial blowup of the longitudinal momentum spread. An efficient cooling method is essential for enhancing the luminosity, while a high acceleration gradient would scale down the collider complex to a reasonable size. The conceptual design of a 250×250 GeV storage ring collider is outlined here. Two functional cells (accelerating and cooling) are described in more detail. The fundamental basis for this collider is that the μ± beams are not destroyed by either radiation like e± or hadronic interactions like [Formula: see text] thus allowing solid state (crystal) components to play a significant role. Assuming integration of two crucial functionalities (cooling and acceleration) into corresponding cells, such a collider would have a few thousands of various crystal components.

Styles APA, Harvard, Vancouver, ISO, etc.

13

PETTI, LUCIA, MASSIMO RIPPA, ANGELA FIORE, LIBERATO MANNA et PASQUALE MORMILE. « DYNAMIC ORIENTATIONAL PHOTO-REFRACTIVE GRATINGS OBSERVED IN CdSe/CdS NANORODS DOPED NEMATIC LIQUID CRYSTAL CELLS ». Journal of Nonlinear Optical Physics & ; Materials 19, n^o 01 (mars 2010) : 111–21. http://dx.doi.org/10.1142/s0218863510005066.

Texte intégral

Résumé :

We observed an orientational photo-refractive effect in semiconductor CdSe/CdS nanorods-doped nematic liquid crystal cells homeotropically aligned. In order to study the photo-refractive and the orientational responses of this cell, we employed both asymmetric two-beam coupling (TBC) to measure two beam coupling gain under the influence of an applied electric field and forced light scattering technique. An optical index grating was written in the device in a holographic tilted configuration by overlapping two laser beams at 514 nm. Self diffraction of the writing beams and diffraction of a probe beam at 633 nm were measured. A high TBC gain coefficient of 270 cm-1 was achieved at a DC field applied of 3.4 V/μm. First-order diffraction efficiencies were evaluated with a maximum efficiency of 7% in the dynamic grating with a nonlinear refractive index, n2, 4 × 10-2 cm2/W for E0 = 3 V /μ m .

Styles APA, Harvard, Vancouver, ISO, etc.

14

Völkl, E., L. F. Allard, B. Frost et T. A. Nolan. « Quanitative aspects of electron diffraction using electron holography ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 616–17. http://dx.doi.org/10.1017/s0424820100139457.

Texte intégral

Résumé :

Off-axis electron holography has the well known ability to preserve the complex image wave within the final, recorded image. This final image described by I(x,y) = I(r) contains contributions from the image intensity of the elastically scattered electrons IeI (r) = |A(r) exp (iΦ(r)) |, the contributions from the inelastically scattered electrons IineI (r), and the complex image wave Ψ = A(r) exp(iΦ(r)) as:(1) I(r) = IeI (r) + Iinel (r) + μ A(r) cos(2π Δk r + Φ(r))where the constant μ describes the contrast of the interference fringes which are related to the spatial coherence of the electron beam, and Φk is the resulting vector of the difference of the wavefront vectors of the two overlaping beams. Using a software package like HoloWorks, the complex image wave Ψ can be extracted.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Akhmedov, Sherzod, Khodjiakmal Aripov, Ruslan Ospanov, Ilhom Mirzaolimov et Temurbek Kenjayev. « Strength of reinforced concrete T-beams of bridges reinforced with external reinforcement from fabric polymeric composites ». E3S Web of Conferences 401 (2023) : 01068. http://dx.doi.org/10.1051/e3sconf/202340101068.

Texte intégral

Résumé :

Work is devoted to rehabilitating damaged, injured reinforced concrete T-beams of bridges of carbon fibre-reinforced plastic materials. Estimating beams' resistance at shear depended on the percent of longitudinal working reinforcing- μ, attitudes of flight of shear to a working height of section - av/ho, an interval, quantity, and orientation of CFFM strips. The mechanism of destruction and estimation of bearing ability strengthened damaged and intact Т-beams are investigated at shear. Results of deformations of the stretched working and cross-section armature, deformations of concrete on the height of beams and in strips CFFM from loading. The influence of CFFM on the bearing ability and character of the destruction of beams is investigated.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Han, Sang Mook, et Qing Yong Guo. « Analysis on the Moment-Curvature Relationship for Prestressed UHPFRC Beams without Stirrup ». Advanced Materials Research 255-260 (mai 2011) : 236–40. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.236.

Texte intégral

Résumé :

To simplify the analysis, an elastic perfectly plastic stress-strain law was presented for UHPFRC. The post-cracking behavior was described by the average constant post-crack tensile strength. A strain parameter μ is proposed to evaluate the performance and efficiency of steel fibre reinforcement. 8 rectangular beams were tested in this investigation. Based on the proposed constitutive model, the full history of their flexural moment-curvature relationship for UHPFRC beams was calculated and compared with experimental data on prestressed UHPFRC beams. Good agreement between calculated strengths and experimental data was obtained.

Styles APA, Harvard, Vancouver, ISO, etc.

17

Hofzi SHLIOH, Nawras, Hayder FAHIM et Mohammed Yahya HADI. « RADIATION BEHAVIOR IN BIOLOGICAL COMPOUND : EXPLORING MASS ATTENUATION AND EFFECTIVE ATOMIC NUMBERS FOR GAMMA-RAY INTERACTION ». MINAR International Journal of Applied Sciences and Technology 06, n^o 01 (1 mars 2024) : 321–33. http://dx.doi.org/10.47832/2717-8234.18.23.

Texte intégral

Résumé :

This study involved the measurement of mass attenuation coefficients (μ/ρ) for fatty acids across a range of photon energies (from 122 keV to 1330 keV). These measurements were conducted through transmission experiments employing collimated beams generated by 57Co, 133Ba, 22Na 137Cs, 54Mn, and 60Co sources, each producing beams with a diameter of 0.52 cm. The detection of attenuated radiation was achieved using a NaI (Tl) scintillation detector with an energy resolution of 8.2% at 663 keV. The obtained experimental values of (μ/ρ) were subsequently used to calculate the atomic cross-sections (σa), electronic crosssections (σe), effective atomic numbers (Zeff), and electron densities (Neff). Notably, the study revealed that (μ/ρ), σa, and σe exhibited an initial decrease with increasing photon energy, stabilizing at higher energy levels. In contrast, Zeff and Neff remained relatively constant with changing energy levels. In addition, the research acknowledged that deviations in experimental results for radiological parameters may be influenced by the physical and chemical surroundings of the substances under investigation. Encouragingly, the experimental findings were found to be consistent with values from the WinXCom database, affirming their accuracy and reliability. These outcomes contribute to a deeper understanding of the photon interaction characteristics of these biological substances across diverse energy spectra.

Styles APA, Harvard, Vancouver, ISO, etc.

18

Lai, Jun, Jian Cai, Qing-Jun Chen, An He et Mu-Yang Wei. « Influence of Crack Width on Chloride Penetration in Concrete Subjected to Alternating Wetting–Drying Cycles ». Materials 13, n^o 17 (28 août 2020) : 3801. http://dx.doi.org/10.3390/ma13173801.

Texte intégral

Résumé :

To investigate the durability of reinforced concrete (RC) beams under the combined actions of transverse cracks and corrosion, corrosion tests were conducted on a total of eight RC beams with different water–cement ratios and cracking states. The effects of the transverse crack width, water–cement ratio, and the length of the wetting–drying cycle on the distribution of the free chloride concentration, the cross-sectional loss of the tensile steel bars, and the chloride diffusion coefficient are analyzed. The results show that the widths of the transverse crack and the water–cement ratio of concrete greatly affected the chloride profile and content of the RC beam specimens. Specifically, the chloride contents in all the cracked RC beams at the depth of the steel bar exceeded the threshold value of 0.15%. As the width of the cracks increased, the chloride concentration and penetration of the cracked concrete beam increased. However, the chloride concentration at the reinforcement position did not seem to be obviously affected by increasing the wetting–drying cycles from 182 days to 364 days. Moreover, the decrease of the water–cement ratio effectively inhibited the penetration of chloride ions in the RC beam specimens. In terms of the cross-sectional loss of the steel bars, the average loss of the steel bar increases with increasing crack width for the beams with 182-day cycles, while the effect of crack width on the average loss is not as noticeable for the beams with 364-day cycles. Finally, a model is proposed to predict the relationship between the crack width influence coefficient, μ, and the crack width, w, and this model shows good agreement with the experimental results.

Styles APA, Harvard, Vancouver, ISO, etc.

19

DIWAN, MILIND V., et HONG MA. « TESTS OF THE STANDARD MODEL USING MUON POLARIZATION ASYMMETRIES IN KAON DECAYS ». International Journal of Modern Physics A 16, n^o 14 (10 juin 2001) : 2449–71. http://dx.doi.org/10.1142/s0217751x01003330.

Texte intégral

Résumé :

We have examined the physics and the experimental feasibility of studying various kaon decay processes in which the polarization of a muon in the final state is measured. Valuable information on CP violation, the quark mixing (CKM) matrix, and new physics can be obtained from such measurements. We have considered muon polarization in KL→μ+μ- and K→πμ+μ- decays. Although the effects are small, or difficult to measure because of the small branching ratios involved, these studies could provide clean measurements of the CKM parameters. The experimental difficulty appears comparable to the observation of [Formula: see text]. New sources of physics, involving nonstandard CP violation, could produce effects observable in these measurements. Limits from new results on the neutron and electron electric dipole moment, and [Formula: see text] in neutral kaon decays, do not eliminate certain models that could contribute to the signal. A detailed examination of muon polarization out of the decay plane in K+→μ+π0ν and K+→μ+νγ decays also appears to be of interest. With current kaon beams and detector techniques, it is possible to measure the T-violating polarization for K+→μ+π0ν and with uncertainties approaching ~10-4. This level of sensitivity would provide an interesting probe of new physics.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Rossini, R., R. Benocci, R. Bertoni, M. Bonesini, S. Carsi, M. Clemenza, A. de Bari et al. « Characterisation of a low-momentum high-rate muon beam monitor for the FAMU experiment at the CNAO-XPR beam facility ». Journal of Instrumentation 19, n^o 01 (1 janvier 2024) : C01024. http://dx.doi.org/10.1088/1748-0221/19/01/c01024.

Texte intégral

Résumé :

Abstract The FAMU experiment aims at an indirect measurement of the Zemach radius of the proton. The measurement is carried out on muonic hydrogen atoms (μH) produced through the low-momentum (50–60 MeV/c) muon beam a the RIKEN-RAL μ- facility. The particle flux plays an important role in this measurement, as it is proportional to the number of μH atoms produced, which is the target of the FAMU experimental method. The beam monitor calibration technique and results, presented here, are meant to extract a reliable estimation of the muon flux during the FAMU data taking. These measurements were carried out at the CNAO synchrotron in Pavia, Italy, using proton beams and supported by Monte Carlo simulation of the detector in Geant4.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Wang, Xinhao, Yingchun Wu, Dongyan Xu, Botong Wen, Qimeng Lv et Xuecheng Wu. « Synthetic aperture rainbow refractometry ». Optics Letters 47, n^o 20 (4 octobre 2022) : 5272. http://dx.doi.org/10.1364/ol.471103.

Texte intégral

Résumé :

This work proposed a synthetic aperture rainbow refractometry (SARR) by synthesizing rainbow signals of the same droplet with dual-wavelength laser beams, in order to increase the aperture of rainbow refractometry. In this way, the SARR can apply to long distance and small droplets measurement. An achromatic imaging system, which simultaneously records while separating the two rainbow signals in two channels of a color image, is elaborately designed. A data processing algorithm is developed to retrieve the optimal droplet refractive index and size. Numerical simulations of different droplet sizes from 10 μ m to 200 μ m certify the viability of the SARR. Proof-of-concept experiments of micron-sized ethanol droplets are performed with 1650 mm measurement distance. Results show that the SARR can accurately measure droplet refractive index and size with uncertainties of 2.3 × 10−4 and 2 μ m, respectively. The feasibility and accuracy of the proposed SARR are successfully demonstrated, paving the way for rainbow refractometry applied to large-scale industrial applications.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Geipel, T., W. Mader et P. Pirouz. « The effect of temperature on high-resolution TEM image contrast ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 640–41. http://dx.doi.org/10.1017/s0424820100139573.

Texte intégral

Résumé :

Temperature affects both elastic and inelastic scattering of electrons in a crystal. The Debye-Waller factor, B, describes the influence of temperature on the elastic scattering of electrons, whereas the imaginary part of the (complex) atomic form factor, fc = fr + ifi, describes the influence of temperature on the inelastic scattering of electrons (i.e. absorption). In HRTEM simulations, two possible ways to include absorption are: (i) an approximate method in which absorption is described by a phenomenological constant, μ, i.e. fi; - μfr, with the real part of the atomic form factor, fr, obtained from Hartree-Fock calculations, (ii) a more accurate method in which the absorptive components, fi of the atomic form factor are explicitly calculated. In this contribution, the inclusion of both the Debye-Waller factor and absorption on HRTEM images of a (Oll)-oriented GaAs crystal are presented (using the EMS software.Fig. 1 shows the the amplitudes and phases of the dominant 111 beams as a function of the specimen thickness, t, for the cases when μ = 0 (i.e. no absorption, solid line) and μ = 0.1 (with absorption, dashed line).

Styles APA, Harvard, Vancouver, ISO, etc.

23

La Via, Francesco, Luca Belsito, Ferri Matteo, Sergio Sapienza, Alberto Roncaglia, Marcin Zielinski et Viviana Scuderi. « Residual Stress Measurement by Raman on Surface-Micromachined Monocrystalline 3C-SiC on Silicon on insulator ». Materials Science Forum 1062 (31 mai 2022) : 320–24. http://dx.doi.org/10.4028/p-04623q.

Texte intégral

Résumé :

In this work, we investigate, by μ-Raman spectroscopy the distribution of stress field on a micro-machined structures. They were realized on a 3C-SiC substrate, grown on a Silicon On Insulator (SOI) wafer, after lithography and etching processes. Various structures, such as strain gauge, single and double clamped beams, were analyzed, showing different stress distributions. All the structures show an intense variation of stress close to the undercut region.

Styles APA, Harvard, Vancouver, ISO, etc.

24

Skalozub, V., et I. Kucher. « Observables for model-independent detections of Z′ boson at the ILC ». International Journal of Modern Physics A 30, n^o 16 (9 juin 2015) : 1550087. http://dx.doi.org/10.1142/s0217751x15500876.

Texte intégral

Résumé :

The integral observables for model-independent detections of Abelian Z′ gauge boson in e+e- → μ+μ-(τ+τ-) process with unpolarized beams at the ILC energies are proposed. They are based on the differential cross-section of deviations from the standard model predictions calculated with a low energy effective Lagrangian and taking into consideration the relations between the Z′ couplings to the fermions derived already. Due to these relations, the cross-section exhibits angular distribution giving a possibility for introducing one- or two-parameter observables which effectively fit the mass mZ′, the axial-vector [Formula: see text] and the product of vector couplings vevμ(vevτ). A discovery reach for the Z′ is estimated for two of introduced observables. Determination of the basic Z′ model is discussed. Comparison with other results and approaches is given.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Поликутин, Алексей, Aleksey Polikutin, Юрий Потапов, Yuriy Potapov, Артем Левченко et Artem Levchenko. « Prerequisites for accounting of fiber reinforcement when calculating normal sections of fibrorubcon beams ». Construction and Architecture 7, n^o 1 (19 avril 2019) : 66–69. http://dx.doi.org/10.29039/article_5ca75fa7e6c350.08575880.

Texte intégral

Résumé :

Develop recommendations for the use of polymer-concrete bending structures is impossible without the creation or optimization of existing methods of calculation, this is especially true for bending elements that use multi-level reinforcement. Для применения (especially under the influence of aggressive environment) for use as a material for the manufacture of bending structures, we offer rubber concrete. – polymer-concrete, which is characterized by high strength characteristics. It is important to note that the composition of fibrorubcon used industrial waste such as fly ash and steel cord. Beams made from cauton and fibrocahuton were tested for pure bending - the most characteristic form of loading in the study of such elements. As a result of the theoretical studies of polymer concrete beams, the prerequisites were established for the calculation of the first group of limit states of rubcon beams and the method for calculating fibrorubcon beams was optimized. It was determined that fiber reinforcement with a percentage of reinforcement by mass of the rubcon element equal to 2.5% corresponds to the work of rod longitudinal reinforcement with a value of μ = 0.34%.

Styles APA, Harvard, Vancouver, ISO, etc.

26

Osterhoff, Markus, Anna-Lena Robisch, Jakob Soltau, Marina Eckermann, Sebastian Kalbfleisch, Dina Carbone, Ulf Johansson et Tim Salditt. « Focus characterization of the NanoMAX Kirkpatrick–Baez mirror system ». Journal of Synchrotron Radiation 26, n^o 4 (3 juin 2019) : 1173–80. http://dx.doi.org/10.1107/s1600577519003886.

Texte intégral

Résumé :

The focusing and coherence properties of the NanoMAX Kirkpatrick–Baez mirror system at the fourth-generation MAX IV synchrotron in Lund have been characterized. The direct measurement of nano-focused X-ray beams is possible by scanning of an X-ray waveguide, serving basically as an ultra-thin slit. In quasi-coherent operation, beam sizes of down to 56 nm (FWHM, horizontal direction) can be achieved. Comparing measured Airy-like fringe patterns with simulations, the degree of coherence |μ| has been quantified as a function of the secondary source aperture (SSA); the coherence is larger than 50% for SSA sizes below 11 µm at hard X-ray energies of 14 keV. For an SSA size of 5 µm, the degree of coherence has been determined to be 87%.

Styles APA, Harvard, Vancouver, ISO, etc.

27

Kaneko, Kazuhiro, Atsushi Ochiai, Hiroaki Ikematsu, Tomonori Yano, Keiko Minashi, Takashi Kojima, Yasuhiro Oono, Atsushi Ohtsu et Hiroyasu Esumi. « μ-Vois, a Novel Three-Dimensional Microstructure Imaging System Using Near-Infrared Beams ». Gastroenterology 140, n^o 5 (mai 2011) : S—751. http://dx.doi.org/10.1016/s0016-5085(11)63122-3.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

28

Fox, Patrick J., Sergo Jindariani et Vladimir Shiltsev. « DIMUS : super-compact Dimuonium Spectroscopy collider at Fermilab ». Journal of Instrumentation 18, n^o 08 (1 août 2023) : T08007. http://dx.doi.org/10.1088/1748-0221/18/08/t08007.

Texte intégral

Résumé :

Abstract While dimuonium (μ + μ -) — the “smallest QED atom” — has not yet been observed, it is of utmost fundamental interest. By virtue of the larger mass, dimuonium has greater sensitivity to beyond the standard model (BSM) effects than its cousins positronium or muonium, both discovered long ago, while not suffering from large QCD uncertainties. Dimuonium atoms can be created in e + e - collisions with large longitudinal momentum, allowing them to decay a small distance away from the beam crossing point and avoid prompt backgrounds. We envision a unique cost-effective and fast-timeline opportunity for copious production of (μ + μ -) atoms at the production threshold via a modest modification of existing Fermilab Accelerator Science and Technology (FAST) facility to arrange collisions of 408 MeV electrons and positrons at a 75° angle. This compact 23 m circumference collider (DIMUS) will allow for precision tests of QED and open the door for searches for new physics coupled to the muon. The FAST facility is perfectly suited for DIMUS as there are existing SRF accelerators and infrastructure, capable of producing high energy, high current electron and positron beams, sufficient for O(1032)cm2 s-1 luminosity and ∼0.5 million dimuons per year. The expansion will require installation of a second SRF cryomodule, positron production and accumulation system, fast injection/extraction kickers and two small circumference intersecting rings. An approximately meter-sized detector with several layers of modern pixelated silicon detector and crystal-based electromagnetic calorimeters will ensure observation of the decays of dimuonium to electron-positron pairs in presence of the Bhabba scattering background. An expansion of the system to include solenoidal magnet outside of the calorimeter system, a layer of steel shielding behind the magnet, and a set of dedicated muon detectors would extend the physics program of DIMUS to include precision studies of rare processes with muons, pions, and η mesons produced in e + e - collisions.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Saqib, Muhammad, Muhammad Mubasher Saleem, Naveed Mazhar, Saif Awan et Umar Shahbaz Khan. « Design and Analysis of a High-Gain and Robust Multi-DOF Electro-thermally Actuated MEMS Gyroscope ». Micromachines 9, n^o 11 (5 novembre 2018) : 577. http://dx.doi.org/10.3390/mi9110577.

Texte intégral

Résumé :

This paper presents the design and analysis of a multi degree of freedom (DOF) electro-thermally actuated non-resonant MEMS gyroscope with a 3-DOF drive mode and 1-DOF sense mode system. The 3-DOF drive mode system consists of three masses coupled together using suspension beams. The 1-DOF system consists of a single mass whose motion is decoupled from the drive mode using a decoupling frame. The gyroscope is designed to be operated in the flat region between the first two resonant peaks in drive mode, thus minimizing the effect of environmental and fabrication process variations on device performance. The high gain in the flat operational region is achieved by tuning the suspension beams stiffness. A detailed analytical model, considering the dynamics of both the electro-thermal actuator and multi-mass system, is developed. A parametric optimization is carried out, considering the microfabrication process constraints of the Metal Multi-User MEMS Processes (MetalMUMPs), to achieve high gain. The stiffness of suspension beams is optimized such that the sense mode resonant frequency lies in the flat region between the first two resonant peaks in the drive mode. The results acquired through the developed analytical model are verified with the help of 3D finite element method (FEM)-based simulations. The first three resonant frequencies in the drive mode are designed to be 2.51 kHz, 3.68 kHz, and 5.77 kHz, respectively. The sense mode resonant frequency is designed to be 3.13 kHz. At an actuation voltage of 0.2 V, the dynamically amplified drive mode gain in the sense mass is obtained to be 18.6 µm. With this gain, a capacitive change of 28.11 f F and 862.13 f F is achieved corresponding to the sense mode amplitude of 0.15 μ m and 4.5 μ m at atmospheric air pressure and in a vacuum, respectively.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Moutsopoulou, Amalia, Markos Petousis, Georgios E. Stavroulakis, Anastasios Pouliezos et Nectarios Vidakis. « μ-Analysis and μ-Synthesis Control Methods in Smart Structure Disturbance Suppression with Reduced Order Control ». Algorithms 17, n^o 2 (6 février 2024) : 73. http://dx.doi.org/10.3390/a17020073.

Texte intégral

Résumé :

In this study, we created an accurate model for a homogenous smart structure. After modeling multiplicative uncertainty, an ideal robust controller was designed using μ-synthesis and a reduced-order H-infinity Feedback Optimal Output (Hifoo) controller, leading to the creation of an improved uncertain plant. A powerful controller was built using a larger plant that included the nominal model and corresponding uncertainty. The designed controllers demonstrated robust and nominal performance when handling agitated plants. A comparison of the results was conducted. As an example of a general smart structure, the vibration of a collocated piezoelectric actuator and sensor was controlled using two different approaches with strong controller designs. This study presents a comprehensive simulation of the oscillation suppression problem for smart beams. They provide an analytical demonstration of how uncertainty is introduced into the model. The desired outcomes were achieved by utilizing Simulink and MATLAB (v. 8.0) programming tools.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Kuraev, E. A., A. Schiller et V. G. Serbo. « The γγ→μ+μ−e+e− and γγ→e+e−e+e− reactions as main calibration processes for high-energy γγ colliding beams ». Nuclear Physics B 256 (janvier 1985) : 189–210. http://dx.doi.org/10.1016/0550-3213(85)90391-8.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

32

Arena, A., G. Cantatore et M. Karuza. « Digital holographic interferometry method for tracking detector modules displacement ». Journal of Instrumentation 18, n^o 11 (1 novembre 2023) : C11030. http://dx.doi.org/10.1088/1748-0221/18/11/c11030.

Texte intégral

Résumé :

Abstract In high energy particle physics scattering experiments, the precision of the reconstructed particle tracks can be fundamental. For this reason, a method for detecting the displacement of tracking detector modules is developed. The modules are silicon planes mounted on a frame and used in the MUonE project, which aims at a precision measurement of the scattering angle of elastic muon-electron scattering. From the scattering angle, the hadronic contribution to the anomalous magnetic moment of the muon is extracted. To achieve the desired accuracy, the position of the tracking detector planes must be monitored. The allowable relative displacements must be less than 10 μ m. To meet the specifications and to monitor as large an area of the detector as possible, a digital holographic interferometer was developed. It is based on a novel lens-less design in off-axis holographic geometry. Light from a fiber-coupled laser source is split by a fiber beam splitter, with one output used to illuminate the detector plane and the other for the reference beam. The two beams produce an interference pattern on a CMOS image sensor. To obtain relative displacement information, successive images are superimposed on an initial reference image and reconstructed by solving the Rayleigh-Sommerfeld diffraction integral taking into account the spherical wavefronts of the beams. The interference fringes that appear in the reconstructed holographic image provide a measure of the relative displacement of the detector plane compared to the initial position. The performance of the reconstruction method used was verified with the proposed setup at a real tracking station.

Styles APA, Harvard, Vancouver, ISO, etc.

33

Sandacz, Andrzej. « Hard exclusive meson production in muon scattering at COMPASS ». EPJ Web of Conferences 270 (2022) : 00006. http://dx.doi.org/10.1051/epjconf/202227000006.

Texte intégral

Résumé :

We report on measurements of hard exclusive muoproduction of ρ0, ω and π0 mesons on the proton at COMPASS using 160 GeV/c polarized μ+ and μ− beams scattering off a liquid hydrogen target. The extracted Spin Density Matrix Elements for vector mesons indicate a violation of s-channel helicity conservation for transitions of transversely polarized virtual photons to longitudinally polarized vector mesons, γT → VL, where V denotes ρ0 or ω meson. Additionally, for ρ0 production we observe a dominant contribution of natural-parity-exchange transitions and a small contribution of unnaturalparity-exchange transitions. On the contrary, the contribution of unnaturalparity-exchange for ω production is significant and it decreases with increasing W, being still non-negligible at the largest W values accessible at COMPASS. Further, we present also the absolute value of the differential cross section for exclusive π0 production and its dependence on squared four-momentum transfer t and azimuthal angle ø between the scattering plane and π0 production plane. The results provide an important input for modeling Generalized Parton Distribution (GPDs), and in particular to constrain chiral-odd (transversity) GPDs.

Styles APA, Harvard, Vancouver, ISO, etc.

34

Beveridge, John L., Jacob Doornbos, David M. Garner, Donald J. Arseneau, Ivan D. Reid et Masayoshi Senba. « A spin rotator for surface μ+ beams on the new M20 muon channel at TRIUMF ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 240, n^o 2 (octobre 1985) : 316–22. http://dx.doi.org/10.1016/0168-9002(85)90642-4.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

35

MILNE, W. I., J. ROBERTSON, B. S. SATYANARAYANA et A. HART. « FIELD EMISSION FROM CARBON FILMS GROWN BY THE CATHODIC ARC PROCESS ». International Journal of Modern Physics B 14, n^o 02n03 (30 janvier 2000) : 301–7. http://dx.doi.org/10.1142/s0217979200000303.

Texte intégral

Résumé :

By using the catholic vacuum are deposition process, carbon films with variable sp 3/ sp 2 bonding ratio can be deposited on a variety of substrates at room temperature. The morphology of the films can be varied from the mirror like smooth tetrahedrally bonded carbon (ta-C) films through nanocluster to fibrous type carbon by altering the deposition parameters. This paper reviews the work carried out on Field Emission from such carbon films and compares the results with those on nanocluster films prepared using supersonic cluster beams. Threshold fields as low as 1 V /μ m with emission site densities of up to 104-105/ cm 2 have been obtained.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Oliveira, Leandro, Warlley Campos et Marcio Rocha. « Optical Trapping and Manipulation of Superparamagnetic Beads Using Annular-Shaped Beams ». Methods and Protocols 1, n^o 4 (20 novembre 2018) : 44. http://dx.doi.org/10.3390/mps1040044.

Texte intégral

Résumé :

We propose an optical tweezers setup based on an annular-shaped laser beam that is efficient to trap 2.8 μ m-diameter superparamagnetic particles. The optical trapping of such particles was fully characterized, and a direct absolute comparison with a geometrical optics model was performed. With this comparison, we were able to show that light absorption by the superparamagnetic particles is negligible for our annular beam tweezers, differing from the case of conventional Gaussian beam tweezers, in which laser absorption by the beads makes stable trapping difficult. In addition, the trap stiffness of the annular beam tweezers increases with the laser power and with the bead distance from the coverslip surface. While this first result is expected and similar to that achieved for conventional Gaussian tweezers, which use ordinary dielectric beads, the second result is quite surprising and different from the ordinary case, suggesting that spherical aberration is much less important in our annular beam geometry. The results obtained here provide new insights into the development of hybrid optomagnetic tweezers, which can apply simultaneously optical and magnetic forces on the same particles.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Tsuji, Kouichi, et Filip Delalieux. « Feasibility study of three-dimensional XRF spectrometry using μ-X-ray beams under grazing-exit conditions ». Spectrochimica Acta Part B : Atomic Spectroscopy 58, n^o 12 (décembre 2003) : 2233–38. http://dx.doi.org/10.1016/s0584-8547(03)00215-5.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

38

Malayappan, Balasubramanian, Narayan Krishnaswamy et Prasant Kumar Pattnaik. « Novel High-Resolution Lateral Dual-Axis Quad-Beam Optical MEMS Accelerometer Using Waveguide Bragg Gratings ». Photonics 7, n^o 3 (18 juillet 2020) : 49. http://dx.doi.org/10.3390/photonics7030049.

Texte intégral

Résumé :

A novel lateral dual-axis a-Si/SiO2 waveguide Bragg grating based quad-beam accelerometer with high-resolution and large linear range has been presented in this paper. The sensor consists of silicon bulk micromachined proof mass suspended by silica beams. Three ridge gratings are positioned on the suspending beam and proof mass to maximize sensitivity and reduce noise. Impact of external acceleration in the sensing direction on the Bragg wavelength of gratings and MEMS structure has been modelled including the effects of strain, stress and temperature variation. Acceleration induces stress in the beam thus modifying the grating period and introducing chirp. The differential wavelength shift with respect to reference grating on the proof mass is the measure of acceleration. To compensate for the effect of the weight of the proof mass and increase the sensitivity of the sensor, electrostatic force of repulsion is applied to the proof mass. For the chosen parameters, the designed sensor has a linear response over a large range and a sensitivity of 30 pm/g. The temperature of surroundings, which acts as noise in sensor performance is compensated by taking differential wavelength shift with respect to reference grating. By design and choice of material, low cross-axis sensitivity is achieved. The proposed design enables a high-resolution well below 1 μ g/ Hz and is suitable for inertial navigation and seismometry applications.

Styles APA, Harvard, Vancouver, ISO, etc.

39

Salvio, Luciana Andrea, Vinicius Di Hipólito, Adriano Luis Martins et Mario Fernando de Goes. « Hybridization quality and bond strength of adhesive systems according to interaction with dentin ». European Journal of Dentistry 07, n^o 03 (juillet 2013) : 315–26. http://dx.doi.org/10.4103/1305-7456.115416.

Texte intégral

Résumé :

ABSTRACT Objective: To evaluate the hybridization quality and bond strength of adhesives to dentin. Materials and Methods: Ten human molars were ground to expose the dentin and then sectioned in four tooth-quarters. They were randomly divided into 5 groups according to the adhesive used: Two single-step self-etch adhesives - Adper Prompt (ADP) and Xeno III (XE), two two-step self-etching primer systems - Clearfil SE Bond (SE) and Adhe SE (ADSE), and one one-step etch-and-rinse system - Adper Single Bond (SB). Resin composite (Filtek Z250) crown buildups were made on the bonded surfaces and incrementally light-cured for 20 s. The restored tooth-quarters were stored in water at 37΀C for 24 h and then sectioned into beams (0.8 mm 2 in cross-section). Maximal microtensile bond strength (μ-TBS) was recorded (0.5 mm/min in crosshead speed). The results were submitted to one-way ANOVA and Tukey′s test (α = 0.05). Thirty additional teeth were used to investigate the hybridization quality by SEM using silver methenamine or ammoniacal silver nitrate dyes. Results: SE reached significantly higher μ-TBS (P < 0.05); no significance was found between ADSE and XE (P > 0.05), and between SB and ADP (P > 0.05); ADSE and XE were significantly higher than SB and ADP (P < 0.05). The bonding interface of SB showed the most intense silver uptake. SE and ADSE showed more favorable hybridization quality than that observed for ADP and XE. Conclusions: The bond strength and hybridization quality were affected by the interaction form of the adhesives with dentin. The hybridization quality was essential to improve the immediate μ-TBS to dentin.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Smolyanskiy, P., B. Bergmann, T. Billoud, P. Burian, M. Sitarz, C. Søndergaard et S. Pospíšil. « Study of charge carrier transport properties and lifetimes in HR GaAs:Cr with Timepix3 ». Journal of Instrumentation 16, n^o 12 (1 décembre 2021) : C12023. http://dx.doi.org/10.1088/1748-0221/16/12/c12023.

Texte intégral

Résumé :

Abstract The response of a Timepix3 (256 × 256 pixels, pixel pitch 55 μm) detector with a 500 μm thick HR GaAs:Cr sensor was studied in proton beams of 125 MeV at the Danish Centre for Particle Therapy in Aarhus, Denmark and in a 120 GeV/c pion beam at the Super-Proton Synchrotron (SPS) at CERN. The sensor was biased at different voltages and irradiated at different angles. The readout chip was configured to operate in electron and hole collection modes. Measurements at grazing angles allowed to see elongated tracks with well-defined impact and exit points, so that charge carrier production depths could be determined in each pixel. We extracted the charge collection efficiencies and the charge carrier drift times as a function of the distance to the pixel plane. It was found that measured proton tracks are shorter in hole collection than in the case of electron collection, which is explained by the shorter lifetime of holes. At an angle of 60 degrees with respect to the sensor normal, the average track length in hole collection was ∼700 μm and 950 μm in electron collection mode. To understand the experimental findings, models describing the properties of HR GaAs:Cr were implemented into the Allpix2 simulation framework. We added previously presented experimental results describing the dependence of the electron drift velocity on the electric field and validated the response by comparing measurement and simulation for various X- and gamma-ray sources in the energy range of 10–60 keV. By comparison of the experimental and the simulated results, the mobility μ h and the lifetime of holes τ h were estimated as μ h = (320 ± 10) cm2/V/s and τ h = (4.5 ± 0.5) ns.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Belafhal, A., E. M. El Halba et T. Usman. « An integral transform and its application in the propagation of Lorentz-Gaussian beams ». Communications in Mathematics 29, n^o 3 (1 décembre 2021) : 483–91. http://dx.doi.org/10.2478/cm-2021-0030.

Texte intégral

Résumé :

Abstract The aim of the present note is to derive an integral transform I = ∫ 0 ∞ x s + 1 e - β x 2 + γ x M k , v ( 2 ζ x 2 ) J μ ( χ x ) d x , I = \int_0^\infty {{x^{s + 1}}{e^{ - \beta x}}^{2 + \gamma x}{M_{k,v}}} \left( {2\zeta {x^2}} \right)J\mu \left( {\chi x} \right)dx, involving the product of the Whittaker function Mk,ν and the Bessel function of the first kind Jµ of order µ. As a by-product, we also derive certain new integral transforms as particular cases for some special values of the parameters k and ν of the Whittaker function. Eventually, we show the application of the integral in the propagation of hollow higher-order circular Lorentz-cosh-Gaussian beams through an ABCD optical system (see, for details [13], [3]).

Styles APA, Harvard, Vancouver, ISO, etc.

42

El-Sahn, NA, DW El-Kassas, HM El-Damanhoury, OM Fahmy, H. Gomaa et JA Platt. « Effect of C-factor on Microtensile Bond Strengths of Low-Shrinkage Composites ». Operative Dentistry 36, n^o 3 (1 mai 2011) : 281–92. http://dx.doi.org/10.2341/10-105-l.

Texte intégral

Résumé :

SUMMARY This study evaluated the microtensile bond strength (μ-TBS) of low-shrinkage composites with their corresponding adhesive systems, Filtek Silorane/Silorane adhesive (SIL, 3M ESPE AG, Seefeld, Germany) and Aelite LS/One-Step Plus (AL, BISCO Inc, Schaumburg, IL, USA) in cavities with different C-factors. Filtek Z250/Adper Single Bond Plus (Z, 3M ESPE, St Paul, MN, USA) was used as a control. Method Standardized Class I cavities were prepared in extracted human molars after removing occlusal enamel. Cavities were assigned into six different C-factors by applying nail polish to four walls, three walls, two walls adjacent to each other, two walls opposite to each other, one wall, or no walls. Resin composites with their corresponding adhesive systems were applied according to manufacturer instructions. Specimens were sectioned to obtain four rectangular beams from the center of the restorations and μ-TBS was measured. Data were analyzed by Weibull survival analysis. Shrinkage stresses of the resin composites were determined after 30 minutes from the start of light-curing using a tensometer testing machine. Flexure elastic modulus was determined using standard procedures, in accordance with ISO 4049. Data for shrinkage stress and elastic modulus were analyzed by one-way analysis of variance followed by a Tukey multiple-comparisons test (p<0.05). Results μ-TBS of both SIL and AL were not affected by different C-factors; however, the bond strength of Z decreased significantly when the C-factor increased. Shrinkage stress results were 0.94±0.1, 1.79±0.18, and 2.14±0.23 MPa for SIL, AL, and Z, respectively. The flexural modulus of both the SIL and the AL was significantly lower than that of Z. Conclusions Increasing C-factor did not negatively affect the bond strength of low-shrinkage composites.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Palladino, Vittorio. « Erratum to “Neutrino beams : μ decay vs. π decay” [Nucl. Instr. and Meth. A 451 (2000) 141–153] ». Nuclear Instruments and Methods in Physics Research Section A : Accelerators, Spectrometers, Detectors and Associated Equipment 455, n^o 2 (décembre 2000) : 502. http://dx.doi.org/10.1016/s0168-9002(00)01029-9.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

44

COX, S. F. J. « ChemInform Abstract : Structure Studies and Dynamics of Muonic Free Radicals ; Radiolysis by Muon Beams and μ SR Spectroscopy ». ChemInform 25, n^o 4 (19 août 2010) : no. http://dx.doi.org/10.1002/chin.199404302.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

45

Pétrélis, François, Stefan Llewellyn Smith et W. R. Young. « Tidal Conversion at a Submarine Ridge ». Journal of Physical Oceanography 36, n^o 6 (1 juin 2006) : 1053–71. http://dx.doi.org/10.1175/jpo2879.1.

Texte intégral

Résumé :

Abstract The radiative flux of internal wave energy (the “tidal conversion”) powered by the oscillating flow of a uniformly stratified fluid over a two-dimensional submarine ridge is computed using an integral-equation method. The problem is characterized by two nondimensional parameters, A and B. The first parameter, A, is the ridge half-width scaled by μh, where h is the uniform depth of the ocean far from the ridge and μ is the inverse slope of internal tidal rays (horizontal run over vertical rise). The second parameter, B, is the ridge height scaled by h. Two topographic profiles are considered: a triangular or tent-shaped ridge and a “polynomial” ridge with continuous topographic slope. For both profiles, complete coverage of the (A, B) parameter space is obtained by reducing the problem to an integral equation, which is then discretized and solved numerically. It is shown that in the supercritical regime (ray slopes steeper than topographic slopes) the radiated power increases monotonically with B and decreases monotonically with A. In the subcritical regime the radiated power has a complicated and nonmonotonic dependence on these parameters. As A → 0 recent results are recovered for the tidal conversion produced by a knife-edge barrier. It is shown analytically that the A → 0 limit is regular: if A ≪ 1 the reduction in tidal conversion below that at A = 0 is proportional to A2. Further, the knife-edge model is shown to be indicative of both conversion rates and the structure of the radiated wave field over a broad region of the supercritical parameter space. As A increases the topographic slopes become gentler, and at a certain value of A the ridge becomes “critical”; that is, there is a single point on the flanks at which the topographic slope is equal to the slope of an internal tidal beam. The conversion decreases continuously as A increases through this transition. Visualization of the disturbed buoyancy field shows prominent singular lines (tidal beams). In the case of a triangular ridge these beams originate at the crest of the triangle. In the case of a supercritical polynomial ridge, the beams originate at the shallowest point on the flank at which the topographic slope equals the ray slope.

Styles APA, Harvard, Vancouver, ISO, etc.

46

Ricciardi, Valerio, Marianna Portaccio, Giuseppe Perna, Maria Lasalvia, Vito Capozzi, Francesco Paolo Cammarata, Pietro Pisciotta et al. « FT-IR Transflection Micro-Spectroscopy Study on Normal Human Breast Cells after Exposure to a Proton Beam ». Applied Sciences 11, n^o 2 (7 janvier 2021) : 540. http://dx.doi.org/10.3390/app11020540.

Texte intégral

Résumé :

Fourier transform infrared micro-spectroscopy (μ-FT-IR) is nowadays considered a valuable tool for investigating the changes occurring in human cells after exposure to ionizing radiation. Recently, considerable attention has been devoted to the use of this optical technique in the study of cells exposed to proton beams, that are being increasingly adopted in cancer therapy. Different experimental configurations are used for proton irradiation and subsequent spectra acquisition. To facilitate the use of μ-FT-IR, it may be useful to investigate new experimental approaches capable of speeding up and simplifying the irradiation and measurements phases. Here, we propose the use of low-e-substrates slides for cell culture, allowing the irradiation and spectra acquisition in transflection mode in a fast and direct way. In recent years, there has been a wide debate about the validity of these supports, but many researchers agree that the artifacts due to the presence of the electromagnetic standing wave effects are negligible in many practical cases. We investigated human normal breast cells (MCF-10 cell line) fixed immediately after the irradiation with graded proton radiation doses (0, 0.5, 2, and 4 Gy). The spectra obtained in transflection geometry showed characteristics very similar to those present in the spectra acquired in transmission geometry and confirm the validity of the chosen approach. The analysis of spectra indicates the occurrence of significant changes in DNA and lipids components of cells. Modifications in protein secondary structure are also evidenced.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Ricciardi, Valerio, Marianna Portaccio, Giuseppe Perna, Maria Lasalvia, Vito Capozzi, Francesco Paolo Cammarata, Pietro Pisciotta et al. « FT-IR Transflection Micro-Spectroscopy Study on Normal Human Breast Cells after Exposure to a Proton Beam ». Applied Sciences 11, n^o 2 (7 janvier 2021) : 540. http://dx.doi.org/10.3390/app11020540.

Texte intégral

Résumé :

Fourier transform infrared micro-spectroscopy (μ-FT-IR) is nowadays considered a valuable tool for investigating the changes occurring in human cells after exposure to ionizing radiation. Recently, considerable attention has been devoted to the use of this optical technique in the study of cells exposed to proton beams, that are being increasingly adopted in cancer therapy. Different experimental configurations are used for proton irradiation and subsequent spectra acquisition. To facilitate the use of μ-FT-IR, it may be useful to investigate new experimental approaches capable of speeding up and simplifying the irradiation and measurements phases. Here, we propose the use of low-e-substrates slides for cell culture, allowing the irradiation and spectra acquisition in transflection mode in a fast and direct way. In recent years, there has been a wide debate about the validity of these supports, but many researchers agree that the artifacts due to the presence of the electromagnetic standing wave effects are negligible in many practical cases. We investigated human normal breast cells (MCF-10 cell line) fixed immediately after the irradiation with graded proton radiation doses (0, 0.5, 2, and 4 Gy). The spectra obtained in transflection geometry showed characteristics very similar to those present in the spectra acquired in transmission geometry and confirm the validity of the chosen approach. The analysis of spectra indicates the occurrence of significant changes in DNA and lipids components of cells. Modifications in protein secondary structure are also evidenced.

Styles APA, Harvard, Vancouver, ISO, etc.

48

Yamazaki, H., K. Ishii, Ts Amartaivan, Y. Takahashi, S. Matsuyama, T. Satoh, S. Sugihara, H. Orihara et C. G. Jon. « PIXE Analysis of Trace Heavy-Metals in River Waters Using an Ion-Exchange Cellulose Filter Paper ». International Journal of PIXE 11, n^o 03n04 (janvier 2001) : 79–92. http://dx.doi.org/10.1142/s012908350100013x.

Texte intégral

Résumé :

A simple but precise method for the PIXE analysis of trace heavy-metals in aqueous samples was developed, in which the PIXE targets were prepared by pre-concentrating heavy metals on a cellulose phosphate ion-exchange filter paper and no additional chemical treatment was required. Heavy metals in trace concentrations were quantitatively retained up to 16.7 μ-equivalent on a sheet of filter paper due to the excellent selectivity for heavy metals and ion-exchange kinetics of phosphate groups in cellulose matrix. Heavy metals of less than 1 μg on one filter paper are precisely and rapidly determined by PIXE analysis using 3-MeV proton beams. The present method is compared with the method preparing a PIXE target for each dissolved species of an element contained in aqueous samples. It will be resulted that the newly developed method enables an on-line PIXE analysis for river waters.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Macek, W. M. « Large-Scale Structure and Termination of the Heliosphere ». Highlights of Astronomy 11, n^o 2 (1998) : 851–56. http://dx.doi.org/10.1017/s1539299600018931.

Texte intégral

Résumé :

AbstractThe question of the boundaries of the heliosphere is considered. The termination heliospheric shock should exist because the solar wind plasma flowing supersonically away from the Sun must make a transition to a subsonic flow. The heliopause is at the outermost extend of the solar wind. Beyond the heliopause lies the (very local) interstellar wind. Intensity of radio emissions at 2 to 3 kHz detected by the Voyager plasma wave instrument in the outer heliosphere can be explained provided that the electron beams generating Langmuir waves exist in the post-shock plasma due to secondary shocks in the compressed solar wind beyond the termination shock. The field strengths of Langmuir waves required to generate the second harmonic emissions are 50 – 100 μ V m-1. Alternatively, the emissions are generated in the vicinity of the heliopause. The Voyager 1 and 2 are proceeding toward a likely source region for Langmuir wave and these waves may be observed in situ in the near future.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Dolique, J. M. « Bremsstrahlung collision contribution to entropy generation and attendant radial expansion in a self-pinched high-power relativistic electron beam propagating in a neutral gas ». Laser and Particle Beams 4, n^o 2 (mai 1986) : 183–91. http://dx.doi.org/10.1017/s0263034600001749.

Texte intégral

Résumé :

In the Bennett-Nordsieck self-pinched regime of high power REB propagation in a neutral atmosphere, radial expansion is generally associated with transverse entropy generation caused by elastic electron-neutral multiple scattering: LN ∝ 1/s′⊥ elast, where LN is the Nordsieck length, the distance for one e-folding of beam radius, and where s′⊥ elast is the elastic collision space rate of transverse mean entropy per particle.For ultrarelativistic beams (γ ≳ 100), the bremsstrahlung, which is the dominant energy loss process, also plays an essential rôle in the radial expansion.A general treatment could be based on the proper time evolution equation of the beam electron pressure 4-tensor pλμ (λ, μ = 0, 1, 2, 3) where source terms linked to elastic, inelastic and bremsstrahlung collisions are introduced, as is also a closure relation. This approach is currently being studied at LPPG.When the various implied scale lengths have clearly different orders of magnitude, a much simpler approximate description may be given.In the λmbrems < z < λstrbrems propagation distance range, where λmbrems is the depth threshold beyond which bremsstrahlung scattering becomes multiple, and λstrbrems a characteristic distance for bremsstrahlung straggling, the rôle of bremsstrahlung in radial expansion is similar to that of elastic multiple scattering. The calculated s′⊥ brems/s′⊥ elast increases rapidly with both propagation distance and beam electron energy. For γ ≫ 103, the bremsstrahlung transverse entropy source term s′⊥ brems is no more negligible before s′⊥ elast.In the z > λstrbrems propagation distance range, where bremsstrahlung straggling is dominant, an evaluation of its effect is deduced by applying the Haftel–Lampe–Aviles criterion to a statistical study of this straggling. A completely different estimation, based on an oversimplified version of the above-cited general thermodynamic method, gives a result which is in rather good agreement.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Μ-Beams »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres