scholarly journals Detection of background thermal neutrons in a modified low-background germanium gamma-ray spectrometer

2019 ◽  
Vol 322 (3) ◽  
pp. 1331-1339
Author(s):  
Jerzy W. Mietelski
Keyword(s):  
High Purity ◽  
Gamma Ray ◽  
Gamma Line ◽  
Thermal Neutrons ◽  
Cyclic Structure ◽  
Low Background ◽  
Gamma Ray Spectrometer ◽  
High Purity Germanium ◽  
Hpge Spectrometer ◽  
Water Moderator

Abstract The paper presents the detection of background neutrons using the 558.4 keV gamma line emitted from excited 114Cd nuclei after neutron induced processes. Stable cadmium and 60 L water moderator were placed inside low background shield of high purity germanium (HPGe) based spectrometer. The method was applied to study diurnal mean variation of background neutron flux. For this purpose 1 h gamma background spectra of modified HPGe spectrometer were collected subsequently for 50.5 days and then summed in 24-h-cycle. Results for the 558.4 keV line are presented along with those of main background lines. The total gamma-ray spectrum was also analysed and results are presented and discussed. No cyclic structure was noticed for all examited lines but 2223 keV, for which some day-night effect is suggested to exist. Test of another moderator made of 108 kg of graphite was done, but the results obtained with water are more promising.

High-purity germanium Gamma-Ray Spectrometer with stirling cycle cryocooler

2002 ◽  
Vol 30 (8) ◽  
pp. 1927-1931 ◽  
Author(s):  
M.N. Kobayashi ◽  
N. Hasebe ◽  
T. Miyachi ◽  
T. Doke ◽  
J. Kikuchi ◽  
...  
Keyword(s):  
High Purity ◽  
Gamma Ray ◽  
Stirling Cycle ◽  
Gamma Ray Spectrometer ◽  
High Purity Germanium

scholarly journals A Low Background Gamma Ray Spectrometer with Anticosmic Shielding

2016 ◽  
Vol 26 (1) ◽  
pp. 93
Author(s):  
Nguyen Quoc Hung ◽  
Vo Hong Hai ◽  
Tran Kim Tuyet ◽  
Ho Lai Tuan
Keyword(s):  
Nuclear Physics ◽  
Gamma Ray ◽  
Gamma Line ◽  
Background Suppression ◽  
Background Count ◽  
Background Count Rate ◽  
Low Background ◽  
Lead Shield ◽  
Gamma Ray Spectrometer ◽  
National University

The article describes a gamma ray spectrometer protected by a lead shield (Model 747E Canberra lead shield) and an active shield made of an 80~cm \(\times\) 80~cm \(\times\) 3~cm plastic scintillator plate in anticoincidence on top of the lead shield. The detector used as low background gamma-spectrometer is a high purity Germanium crystal of model GC2018 Canberra. The background count rate currently achieved (30-2400 keV) is 1.27 cps without anticoincidence. The level of background suppression obtained from the active protection is 0.80 overall and about 0.43 for the 511 keV gamma line. The gamma ray spectrometer is installed and operated in the Nuclear Laboratory, Department of Nuclear Physics, University of Science, HCMC-Vietnam National University.

scholarly journals Low-background, digital gamma-ray spectrometer with BEGe detector and active shield: commissioning, optimisation and software development

2019 ◽  
Vol 322 (3) ◽  
pp. 1311-1321
Author(s):  
Krzysztof Gorzkiewicz ◽  
Jerzy Wojciech Mietelski ◽  
Renata Kierepko ◽  
Kamil Brudecki
Keyword(s):  
Gamma Ray ◽  
Germanium Detector ◽  
Low Background ◽  
Gamma Ray Spectrometer ◽  
Annihilation Peak ◽  
The Mean ◽  
Plastic Scintillators ◽  
Set Up ◽  
Active Shield ◽  
Broad Energy

Abstract This paper presents results of the development process of low-background, digital gamma-rays spectrometer equipped with Broad Energy Germanium detector (CANBERRA BE5030), multi-layer passive shield and cosmic veto system that consists of five plastic scintillators (SCIONIX EJ-200). Data acquisition is performed using digitizer CAEN DT5725 with CoMPASS software. Output data analysis is carried out with purposely written and developed code VETO. On the basis of conducted tests, acquisition parameters were set up and tuned as well as time delays between all detectors were established. As a result of the configuration process, the mean background counts reduction of 64% in the whole spectrum and 65% in annihilation peak were achieved. This procedure allowed diminishing detection limits of selected isotopes 37% on average.

High-Purity Germanium Technology for Gamma-Ray and X-Ray Spectroscopy

1993 ◽  
Vol 302 ◽  
Author(s):  
L.S. Darken ◽  
C. E. Cox
Keyword(s):  
Cross Section ◽  
Gamma Rays ◽  
Ground State ◽  
High Purity ◽  
Gamma Ray ◽  
Capture Rate ◽  
X Rays ◽  
Hole Capture ◽  
High Purity Germanium ◽  
Energy Gamma

ABSTRACTHigh-purity germanium (HPGe) for gamma-ray spectroscopy is a mature technology that continues to evolve. Detector size is continually increasing, allowing efficient detection of higher energy gamma rays and improving the count rate and minimum detectable activity for lower energy gamma rays. For low-energy X rays, entrance window thicknesses have been reduced to where they are comparable to those in Si(Li) detectors. While some limits to HPGe technology are set by intrinsic properties, the frontiers have historically been determined by the level of control over extrinsic properties. The point defects responsible for hole trapping are considered in terms of the “standard level” model for hole capture. This model originates in the observation that the magnitude and temperature dependence of the cross section for hole capture at many acceptors in germanium is exactly that obtained if all incident s-wave holes were captured. That is, the capture rate is apparently limited by the arrival rate of holes that can make an angular-momentum-conserving transition to a s ground state. This model can also be generalized to other materials, where it may serve as an upper limit for direct capture into the ground state for either electrons or holes. The capture cross section for standard levels σS.L. is given bywhere g is the degeneracy of the ground state of the center after capture, divided by the degeneracy before capture. Mc is the number of equivalent extrema in the band structure for the carrier being captured, mo is the electronic mass, m* is the effective mass, and T is the temperature in degrees Kelvin.

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