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Title: The 210Pb Bremsstrahlung In The Background Of Lead Shields

Abstract

Contemporary theories of dark matter predict that weakly interacting massive particles interact with matter by nuclear recoils leaving in the detector energies up 50 keV. The bremsstrahlung of 210Pb contributes to this spectral region. The 46.5 keV gamma intensity of 210Pb in the background can be easily reduced by inner lining, but the bremsstrahlung from the 1.2 MeV maximal energy beta decay will reach the lead shielded Ge detector. The spectrum of this bremsstrahlung is calculated by numerically fitting the beta spectrum and integrating the Koch-Motz formula. The absorption of the bremsstrahlung spectrum in the lead and detection efficiencies for Ge detector are calculated by the effective solid angle algorithm, using correction for photopeak/compton ratio of cross sections in Ge. By comparison with the measured spectrum, it is shown, that for the lead with 25 Bq/kg of 210Pb, up to 500 keV, the bremsstrahlung contribution to the background is about 20%. The calculated bremsstrahlung intensity is in good agreement with the experimental result derived in Max Planck Institute, Heidelberg.

Authors:
; ; ;  [1]
  1. Department of Physics, Faculty of Sciences, University of Novi Sad, Novi Sad 21 000, Trg Dositeja Obradovica 4 (Serbia)
Publication Date:
OSTI Identifier:
21057297
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 899; Journal Issue: 1; Conference: 6. international conference of the Balkan Physical Union, Istanbul (Turkey), 22-26 Aug 2006; Other Information: DOI: 10.1063/1.2733054; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ABSORPTION; ALGORITHMS; BETA DECAY; BETA SPECTRA; BREMSSTRAHLUNG; COMPARATIVE EVALUATIONS; CORRECTIONS; CROSS SECTIONS; GAMMA SPECTROMETERS; GE SEMICONDUCTOR DETECTORS; KEV RANGE; LEAD; LEAD 210; NONLUMINOUS MATTER; PARTICLE IDENTIFICATION; RECOILS; SHIELDS

Citation Formats

Mrdja, D., Bikit, I., Slivka, J., and Veskovic, M. The 210Pb Bremsstrahlung In The Background Of Lead Shields. United States: N. p., 2007. Web. doi:10.1063/1.2733054.
Mrdja, D., Bikit, I., Slivka, J., & Veskovic, M. The 210Pb Bremsstrahlung In The Background Of Lead Shields. United States. doi:10.1063/1.2733054.
Mrdja, D., Bikit, I., Slivka, J., and Veskovic, M. Mon . "The 210Pb Bremsstrahlung In The Background Of Lead Shields". United States. doi:10.1063/1.2733054.
@article{osti_21057297,
title = {The 210Pb Bremsstrahlung In The Background Of Lead Shields},
author = {Mrdja, D. and Bikit, I. and Slivka, J. and Veskovic, M.},
abstractNote = {Contemporary theories of dark matter predict that weakly interacting massive particles interact with matter by nuclear recoils leaving in the detector energies up 50 keV. The bremsstrahlung of 210Pb contributes to this spectral region. The 46.5 keV gamma intensity of 210Pb in the background can be easily reduced by inner lining, but the bremsstrahlung from the 1.2 MeV maximal energy beta decay will reach the lead shielded Ge detector. The spectrum of this bremsstrahlung is calculated by numerically fitting the beta spectrum and integrating the Koch-Motz formula. The absorption of the bremsstrahlung spectrum in the lead and detection efficiencies for Ge detector are calculated by the effective solid angle algorithm, using correction for photopeak/compton ratio of cross sections in Ge. By comparison with the measured spectrum, it is shown, that for the lead with 25 Bq/kg of 210Pb, up to 500 keV, the bremsstrahlung contribution to the background is about 20%. The calculated bremsstrahlung intensity is in good agreement with the experimental result derived in Max Planck Institute, Heidelberg.},
doi = {10.1063/1.2733054},
journal = {AIP Conference Proceedings},
number = 1,
volume = 899,
place = {United States},
year = {Mon Apr 23 00:00:00 EDT 2007},
month = {Mon Apr 23 00:00:00 EDT 2007}
}
  • The 46.5 keV {gamma}-intensity of 210Pb in the background can be easily reduced by inner lining, but the bremsstrahlung from the 1.2 MeV maximal energy {beta}-decay will reach the lead shielded Ge detector. The spectrum of this bremsstrahlung is calculated by numerically fitting the {beta}-spectrum and integrating the Koch-Motz formula. The adsorption of the bremsstrahlung spectrum in the lead is calculated by the effective solid angle algorithm by comparison with the measured background spectrum. It is shown, that for the lead with 25 Bq/kg of 210Pb, at 100 keV the bremsstrahlung contribution to the background is about 20%.
  • Exposure buildup factors, energy spectra, and angular flux distribution for plane-normal incident and point isotropic source gamma rays of 0.1, 0.5, 1, 3, 6, and 10MeV penetrating two-layer water-lead and lead-water shields are calculated with the point Monte Carlo code EGS4. The effects of bremsstrahlung and fluorescent radiation are included. The value of the buildup factor in the second layer lies between those for infinite media of both materials in two source geometries in the 0.5- to 3-MeV energy range. However, this behavior varies remarkably and is enhanced with a bremsstrahlung contribution, when the source energy is higher than thatmore » corresponding to the minimum in the attenuation coefficient of lead. This varies equally with the fluorescent contribution when the source energy is close to the K edge of lead.« less
  • - A shielded cell around a Na(Tl) crystal scintillation detector is described which was constructed of polyethylenelined paper bags containing 100 pounds each of crushed talc. The cell was 4 ft x 4 ft x 4 ft with 2-ft thick walls. Background in the talc cell ranged from about 200% at low energies to 160% at high energies of that obtained in a lead cell. The cost of the talc cell was about 20% of that of a lead cell. Use of the cell for counting whole-body gamma radiation in humans is described. (C.H.)