Effects of near-source Compton scattering in low-energy γ-ray spectra

Marija Majer10
Estimated H-index: 10
(University of Zagreb),
Milivoj Uroić5
Estimated H-index: 5
(University of Zagreb)
+ 3 AuthorsKsenofont Ilakovac6
Estimated H-index: 6
(University of Zagreb)
Sources
Abstract
Abstract An extension of the previous study of germanium-detector response function for 59.537 keV γ -rays has been made. The continua adjacent to the full-energy peaks, which are due to Compton scattering in atoms in vicinity of the γ -ray emitting atoms (the “shoulders”), were measured with 26.345, 79.623, 80.999, 88.032, 86.554 and 105.338 keV γ -rays for various orientations of the source plates. The changes in the shoulder spectra clearly indicate the importance of the near-source Compton scattering. Previous calculations, that included only single Compton scattering (assuming stationary electrons) and broadening due to the detector resolution, have been improved by including also the broadening due to momentum distributions of atomic electrons, and double Compton scattering. Also, a spectrum has been obtained by a the Monte Carlo calculation. Better fits to the previously reported spectra measured with the 59.537 keV γ -rays have been obtained. The shoulders in the newly measured spectra are also well explained. The calculated ratios of the numbers of pulses in the shoulders and in the corresponding full-energy peaks are in a reasonable agreement with the experimental ratios.
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2015
References11
Newest
Abstract Compton scattering on electrons in materials in the vicinity of low-energy photon-emitting atoms and in the vicinity of the detector sensitive volume causes a continuous distribution below the full-energy peak (the “shoulder”). To study effects of the near-source Compton scattering, a collimator was used in front of a planar germanium detector to reduce the near-detector scattering. The measurements show that even a small mass in vicinity of emitting atoms, such as that of a standard ca...
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Abstract Accurate processing of low-energy X-ray spectra requires detailed knowledge of the detector response function. This has been determined for a high-purity germanium (HPGe) detector by using monochromatized synchrotron radiation in the 1–20 keV energy range. Due to the high peak-to-background ratio, the spectra reveal shapes that were hidden using previous detectors. In addition to escape peaks, features caused by electron interactions characterize the background shape: escape of photoele...
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#1J.Y. Zevallos-Chávez (USP: University of São Paulo)H-Index: 3
#2M. T. F. da Cruz (USP: University of São Paulo)H-Index: 5
Last. M. M. Hindi (Tennessee Technological University)H-Index: 9
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We have developed a function to describe the response of an 8-cm3 germanium detector to photon energies as low as 6 keV, going up to 120 keV. Detection effects like the Ge X-ray escape and Compton scattered photons in the neighborhood of the detector were treated. This study was based on the fit of analytic functions to the features of the experimental spectra, thus revealing the parameters and their dependence on the photon energy. Our response function has 13 parameters and its validity is sho...
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#1John LilleyH-Index: 1
Flow diagram. Editorsa preface to the Manchester Physics Series. Authora s preface. PART I: PRINCIPLES. Chapter 1. Introduction and Basic Concepts. Chapter 2. Nuclear Structure. Chapter 3. Nuclear Instability. Chapter 4. Nuclear Reactions. PART II: INSTRUMENTATIN AND APPLICATIONS. Chapter 5. Interaction of Radiation with Matter. Chapter 6. Detectors and Instrumentation. Chapter 7. Biological Effects of Radiation. Chapter 8. Industrial and Analytical Applications. Chapter 9. Nuclear Medicine. Cha...
#1Myung C. Lee (NCSU: North Carolina State University)H-Index: 2
#2Kuruvilla Verghese (NCSU: North Carolina State University)H-Index: 21
Last. Robin P. Gardner (NCSU: North Carolina State University)H-Index: 25
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Abstract A model for the spectral response function of large volume germanium gamma-ray detectors in the range of incident gamma-ray energies from 60 keV to 6.2 MeV has been developed and applied to a 39% high purity germanium detector. Functional forms for describing the various features of the response function are based either on empirical functions or on analytical expressions of the interaction mechanisms. Improved functions are formulated to give good agreement to the experimental spectra ...
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#1Ksenofont Ilakovac (University of Zagreb)H-Index: 6
#2J. Tudorić-Ghemo (University of Split)H-Index: 2
Last. Miroslav Veskovic (University of Novi Sad)H-Index: 14
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Abstract Coincident detection of radiation, which, following the interaction of incident radiation in one detector, escapes from it and is absorbed in another detector, was studied. Several prominent peaks due to the transfer of energy by germanium characteristic radiation were observed. Their well defined positions allow accurate calibration of energy scales, and the time spectra corresponding to the peaks make possible a detailed analysis of the operation of the coincidence, a good definition ...
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#1Robin P. Gardner (NCSU: North Carolina State University)H-Index: 25
#2A. M. Yacout (NCSU: North Carolina State University)H-Index: 5
Last. Kuruvilla Verghese (NCSU: North Carolina State University)H-Index: 21
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Abstract Simple physical mechanisms implemented by either analog Monte Carlo simulations or analytical models have been used to investigate the Si(Li) and Ge detector response functions for X- and gamma rays, respectively. The mechanisms investigated include the various possible combinations of partial losses of photoelectric and Auger electrons from the detector surfaces and complete losses of the various photons involved such as the Si K X-ray, the 0.511 MeV annihilation photons, and single or...
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#1Stephen M. Seltzer (NIST: National Institute of Standards and Technology)H-Index: 31
Abstract The response of small intrinsic Ge detectors has been calculated for photons incident with energies up to ∼300 keV. The results include the effects of scattering and escape from the detector of the photons and of Ge characteristic X-rays produced in photoelectric absorption. Included also are the effects of the backscattering of photons from material behind the detector. The results, based on Monte Carlo calculations for various photon energies and detector sizes, have been generalized ...
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#1Glenn F KnollH-Index: 1
Chapter 1 Radiation Sources. I. Units And Definitions. II. Fast Electron Sources. III. Heavy Charged Particle Sources. IV. Sources Of Electromagnetic Radiation. V. Neutron Sources. Chapter 2 Radiation Interactions. I. Interaction Of Heavy Charged Particles. II. Interaction Of Fast Electrons. III. Interaction Of Gamma Rays. IV. Interaction Of Neutrons. V. Radiation Exposure And Dose. Chapter 3 Counting Statistics And Error Prediction. I. Characterization Of Data. II. Statistical Models. III. Appl...
#1M. SchumacherH-Index: 1
#2F. SmendH-Index: 1
Last. I BorchertH-Index: 1
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Using the form factor approximation and nonrelativistic Coulomb wavefunctions, cross section profiles for Compton scattering of gamma rays are calculated for all subshells of the atom. Spherical coordinate are used in order to facilitate a straightforward application of self-consistent wavefunctions. Relativistic energy and momentum relations are applied. Numerical data are presented, for Egamma =279 keV and the K-, L- and M-subshells of copper and lead. Comparisons are made with cross section p...
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Cited By3
Newest
#1Lorenzo BruallaH-Index: 16
#2Nora L. Maidana (USP: University of São Paulo)H-Index: 9
Last. Vito R. Vanin (USP: University of São Paulo)H-Index: 14
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Peak efficiency of a non-uniform frontal dead layer planar detector was simulated with the general purpose Monte Carlo radiation transport code PENELOPE. In a previous publication, using experimental data and an analytical model proposed by Seltzer, we found the structure and dimensions of the detectors dead layer. In this work, we used our previous results as input for a Monte Carlo simulation that considered a point source emitting specific photons from 13 to 122 keV, with the energies and emi...
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#1Milivoj Uroić (University of Zagreb)H-Index: 5
#2Marija Majer (University of Zagreb)H-Index: 10
Last. Ksenofont Ilakovac (University of Zagreb)H-Index: 6
view all 4 authors...
Abstract A considerable reduction of background and an improvement of spectra of low-energy γ -rays, measured with a planar high-purity Ge detector, has been achieved using a small source and a careful design of collimators and shielding. The aim of the design was to reduce strongly the detection of scattered radiation. The design of the shielding was based on previous studies by the present authors of effects of near-source scattering on photon spectra. That work has shown the effects of differ...
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