Energy dependence of the bremsstrahlung cross section at the short wavelength limit

Aehlig, A.; Scheer, M.; Zilker, F.

doi:10.1016/0375-9601(75)90538-1

Cited by 3 publications

(3 citation statements)

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“…The experiment aimed at testing the validity of the Elwert-Haug formalism [6,7] for medium-Z elements. Aehlig et al [23] found that, on average, their measured data were somewhat higher than the theoretical Elwert-Haug DDCSs, but the discrepancy did not exceed 20%.…”

Section: Introductionmentioning

confidence: 86%

“…The second experiment was performed by Aehlig, Sheer and Zilker [23], studying four electron kinetic energies in the interval 100-250 keV, in two targets of Cu, and two photon emission angles: 25 q =  and 50 • . To determine the DDCS at 1 k = , simultaneously with the detected photons in a Ge(Li) spectrometer they counted the elastically scattered electrons collected with a surface barrier detector [23]. This relative method circumvents the need to know the thickness of the targets using instead theoretical elastic-scattering cross sections to place the DDCSs on an absolute scale.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of doubly differential electron bremsstrahlung cross sections at the end point (tip) for C, Al, Te, Ta and Au

García-Alvarez

Fernández-Varea

Vanin

et al. 2017

J. Phys. B: At. Mol. Opt. Phys.

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We have used the low-energy beam line of the São Paulo Microtron accelerator to study the maximum energy transfer point (tip) of electron-atom bremsstrahlung spectra for C, Al, Te, Ta and Au. Absolute cross sections differential in energy and angle of the emitted photon were measured for various electron kinetic energies between 20 and 100 keV, and photon emission angles of 35 • , 90 • and 131 • . The bremsstrahlung spectra were collected with three HPGe detectors and their response functions were evaluated analytically. Rutherford backscattering spectrometry allowed us to obtain the thicknesses of the targets with good accuracy. We propose a simple model for the tip region of the bremsstrahlung spectrum emitted at a given angle, whose adjustable parameters are the mean energy of the incident beam and its spread as well as an amplitude. The model was fitted simultaneously to the pulse-height distributions recorded at the three angles, determining the doubly differential cross sections from the corresponding amplitudes. The measured values have uncertainties between 3% and 13%. The agreement of the experimental results with the theoretical partial-wave calculations of Pratt and co-workers depends on the analyzed element and angle but is generally satisfactory. In the case of Al and Au, the uncertainty attributed to the theory is probably overestimated.

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Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Measurement of doubly differential electron bremsstrahlung cross sections at the end point (tip) for C, Al, Te, Ta and Au

García-Alvarez

Fernández-Varea

Vanin

et al. 2017

J. Phys. B: At. Mol. Opt. Phys.

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“…Por outro lado, o regime de onda contínua e a possibilidade de trabalhar com correntes baixas no Microtron, da ordem de nano-ampéres, permitem fazer medidas diretas com detectores de germânio hiperpuro, o que evita os problemas de empilhamento característicos dos aceleradores pulsados. Adicionalmente, a literatura sobre medidas diretas do bremsstrahlung de elétrons com detectores de HPGe [Re72,St72,Ae75], que têm resolução em energia dos fótons uma ordem de grandeza melhor que a das medidas anteriores, é escassa. Dois trabalhos se restringem a energias menores que 0,25 MeV [Re72,Ae75] e um terceiro, com elétrons de 1,84 MeV [St72], encontrou resultados em grande desacordo com a teoria; em análise subsequente, Pratt e…”

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Bremsstrahlung de elétrons no microtron do IFUSP: medidas, simulação e proposta de aplicação ao estudo da ressonância fluorescente nuclear

Pino¹

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The results of the first experiments carried out in the new electron accelerator of the Linear Accelerator Laboratory (LAL) of the Physics Institute of Universidade de São Paulo are reported here. A 1.9 MeV beam line, which allows the use of the injector beam for experimental physics, was added to the original accelerator design. Electron bremsstrahlung spectra for Ag and Au thin targets observed at 30 o and 60 o with respect to the beam direction were collected in a HPGe coaxial detector, whose dimensions, including crystal inner hole dimensions and dead layer thickness, were estimated by means of combined experimental measurements and Monte Carlo simulations with the MCNP code, to evaluate the detector response function to perform the deconvolution of the spectrum. Cross sections for bremsstrahlung yield were determined for the entire measured energy range (100-1910 keV) and for the tip region (1700-1970 keV). The results in the tip region are in agreement with MCNPX and PENELOPE predictions. The possible causes for the disagreement at energies lower than 1800 keV are discussed. The design of a Nuclear Resonance Fluorescence (NRF) setup, aiming the study of dipolar excitations in nuclei with bremsstrahlung photons when the Microtron electron energy reaches 10 MeV, is also shown. The setup was designed with the characteristics of the Microtron building and facilities in mind, and searches to minimize the radiation caused by scattered photons and neutrons from photonuclear reactions. The behavior of the NRF setup elements: converter, collimator, detector shielding and photon beam dump, were studied by simulation as functions of their characteristics-dimensions, shapes, materials-using the MCNPX code. The spectral intensity to be observed by the photon detector in the designed NRF setup with a 27 Al reference target, typical for NRF measurements, was assessed by simulation and shows the feasibility of this sort of experiment with the Microtron. vi vii Dedicatória A minha tia Haydee, a meus pais Lucy, Aldo e Rodolfo, a meu amor Fátima, e à maior alegria de minha vida, Marquitos... A mi tía Haydee, a mis padres Lucy, Aldo y Rodolfo, a mi amor Fátima, y a la mayor alegría de mi vida, Marquitos… viii ix Agradecimentos À Prof. Nora pelos prazos estendidos, pela ajuda insuperável em muitas coisas alem do doutorado, por fazer deste trabalho quase seu segundo Phd., sem ela simplesmente eu não estaria escrevendo estes agradecimentos, Ao Prof. Vito pela linha de baixa energia, pelas correções e sugestões e pelo grande tempo dedicado, A Vicky, sempre agradecido, sem ela para mi o Brasil, fora o carnaval de Rio, as brigas no vôlei das cubanas e as brasileiras..., mas só na TV, Ao Prof. Marcos, meu primeiro orientador, sempre exigente, preciso e disposto a ajudar, A Alexandre e Alfredo por fazerem o Microtron funcionar, por conseguirem superar as múltiplas inconveniências, A Roberto e ao pessoal da oficina mecânica, sempre ágeis e atentos, À Wanda Gabriel Pereira Engel do LAFN pelo preparo dos alvos, À Prof. Márcia de Almeida ...

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Electromagnetic processes at low momentum transfer : a review for users

et al. 1984

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Energy dependence of the bremsstrahlung cross section at the short wavelength limit

Cited by 3 publications

References 8 publications

Measurement of doubly differential electron bremsstrahlung cross sections at the end point (tip) for C, Al, Te, Ta and Au

Measurement of doubly differential electron bremsstrahlung cross sections at the end point (tip) for C, Al, Te, Ta and Au

Bremsstrahlung de elétrons no microtron do IFUSP: medidas, simulação e proposta de aplicação ao estudo da ressonância fluorescente nuclear

Electromagnetic processes at low momentum transfer : a review for users

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