The influence of counting geometry and lining on the Compton continuum in well-type detectors

1996 ◽  
Vol 379 (2) ◽  
pp. 289-292 ◽  
Author(s):  
S.J Gelsema ◽  
M Blaauw ◽  
P Bode
Keyword(s):  
Compton Continuum ◽  
Counting Geometry

Airborne gamma‐ray spectrometric background estimation using full spectrum analysis

Geophysics ◽  
1992 ◽  
Vol 57 (2) ◽  
pp. 279-287 ◽  
Author(s):  
B. R. S. Minty
Keyword(s):  
Gamma Ray ◽  
Atmospheric Radiation ◽  
Compton Continuum ◽  
Full Spectrum ◽  
Background Estimation ◽  
Potassium Sources ◽  
Energy Formula ◽  
A New Technique ◽  
The Vertical Distribution ◽  
Atmospheric Radon

We have developed a new technique for estimating airborne gamma‐ray spectrometric backgrounds. The background comes from three sources, namely aircraft, cosmic and atmospheric (radon) radiation. The aircraft and cosmic components are independently estimated by suitable calibration and the monitoring of a 3–6 MeV “cosmic” channel. Multichannel observations of the spectra are used to estimate the atmospheric background directly based on the observation that for gamma‐ray counts above the Compton continuum, the low energy [Formula: see text] photopeak at 0.609 MeV for atmospheric radiation suffers far less attenuation relative to the [Formula: see text] peak at 1.76 MeV than is the case for radiation from uranium in the ground. Since thorium and potassium sources do not contribute appreciably to these peak countrates, they can be used to calculate the contributions of radon and uranium to the observed spectrum. The technique appears to be less susceptible to errors due to the effects of variations in the vertical distribution of airborne radon and its daughters than upward‐looking detector techniques.

scholarly journals Production of 128I Atoms through 127I (n,γ) 128I Reactions in some Solid Iodocompounds using an (241Am-Be) Neutron Source

2011 ◽  
Vol 3 (2) ◽  
pp. 357-366 ◽  
Author(s):  
M. R. Zaman ◽  
M. A. Hossain ◽  
M. J. A. Sarkar
Keyword(s):  
Solid State ◽  
Neutron Source ◽  
Half Life ◽  
Irradiation Time ◽  
Volume Element ◽  
Nuclear Transformation ◽  
Time Decay ◽  
Chemical Effects ◽  
Counting Geometry ◽  
Zero Time

 Present work reports the production of 128I atoms through 127I (n,g) 128I reactions in six iodine containing compounds (viz. NaI, NaIO3, NaIO4, KI, KIO3 and KIO4) in solid state. An  241Am-Be neutron source has been used for the production of 128 I atoms. The radioactivities produced have been measured by a thin end-window G.M. Counter. The irradiation time and counting geometry were constant throughout the present sets of experiments. Results obtained have been analyzed through time-decay analyses. From the decay curves, the half life of 128I  has been estimated ~25 minutes. The average zero time activities of 128I from three independent measurements in each of NaI, NaIO3.H2O, NaIO4, KI, KIO3 and KIO4 target, have been found 116 ± 2, 92 ± 4, 88 ± 6, 102 ± 6, 98 ± 1 and 93 ± 5 cpm respectively. It is interesting to note that the activities show a decreasing trend while passing through either from NaI to NaIO4 or from KI to KIO4. Results are attributed to the quantity of 128I produced in a specified volume element and, self absorption and self scattering of radiations within the target compounds studied.  Keywords: Iodocompounds; 128I; 241Am-Be neutron source; Chemical effects of nuclear transformation.© 2011 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi:10.3329/jsr.v3i2.6385                 J. Sci. Res. 3 (2), 357-366 (2011)

Validation of aGeant4model of the X-ray fluorescence microprobe at the Australian Synchrotron

2015 ◽  
Vol 22 (2) ◽  
pp. 354-365 ◽  
Author(s):  
Matthew Richard Dimmock ◽  
Martin Daly de Jonge ◽  
Daryl Lloyd Howard ◽  
Simon Alexander James ◽  
Robin Kirkham ◽  
...  
Keyword(s):  
Experimental Validation ◽  
Low Energy ◽  
Beam Model ◽  
Compton Continuum ◽  
Reconstruction Algorithms ◽  
X Ray ◽  
Simulation Process ◽  
Beryllium Window ◽  
Spectral Distributions ◽  
Energy Physics

AGeant4Monte Carlo simulation of the X-ray fluorescence microprobe (XFM) end-station at the Australian Synchrotron has been developed. The simulation is required for optimization of the scan configuration and reconstruction algorithms. As part of the simulation process, a Gaussian beam model was developed. Experimental validation of this simulation has tested the efficacy for use of the low-energy physics models inGeant4for this synchrotron-based technique. The observed spectral distributions calculated in the 384 pixel Maia detector, positioned in the standard back-scatter configuration, were compared with those obtained from experiments performed at three incident X-ray beam energies: 18.5, 11.0 and 6.8 keV. The reduced χ-squared (\chi^{2}_{\rm{red}}) was calculated for the scatter and fluorescence regions of the spectra and demonstrates that the simulations successfully reproduce the scatter distributions. Discrepancies were shown to occur in the multiple-scatter tail of the Compton continuum. The model was shown to be particularly sensitive to the impurities present in the beryllium window of the Maia detector and their concentrations were optimized to improve the \chi^{2}_{\rm{red}} parameterization in the low-energy fluorescence regions of the spectra.

Counting Geometry

1965 ◽  
Vol 27 (6) ◽  
pp. 446-448
Author(s):  
Clyde M. Senger
Keyword(s):  
Counting Geometry

New Free-Release and Sorting Monitors Developed for NPP A-1 Decommissioning, Slovakia

2011 ◽  
Author(s):  
Ondrej Sla´vik ◽  
Alojz Slaninka ◽  
Martin Lisˇtjak ◽  
Kamil Krava´rik ◽  
Igor Pe´ly
Keyword(s):  
Detection Efficiency ◽  
Metrological Certification ◽  
Acquisition Time ◽  
Semiconductor Detectors ◽  
Accuracy Class ◽  
Counting Geometry ◽  
Prototype Test ◽  
Uncertainty Of Measurements ◽  
Indication System ◽  
Calculation Code

A pilot free-release monitoring post with a 600 L container monitor was developed and metrological tested within the 2nd stage of NPP A1 decommissioning project. In order to reduce the volume of contaminated soil monitoring a conceptual design of fast sorting loader shovel monitor (loader’s spoon) was proposed and tested within the project as well. The free-release monitoring post makes use of a pair of electrically cooled lead shielded semiconductor detectors placed into a mounting rack ensuring measurements in either horizontal (container monitoring) or vertical (drum monitoring) counting geometry. For evaluation of measured HPGe spectra the Canberra – Packard ISOCS detection efficiency calculation code was used. A loader is used to change the measured side of the 600 L container. For metrological certification of this monitor a special prototype test container with 24 rod sources inside a regular grid was necessary to design and to use. The mentioned above vertical counting geometry together with an additional drum rotator ensures standard free release monitoring of materials in 200 l rotating drums. Successful metrological qualification of the both counting geometries at SMU Bratislava showed 20% accuracy class. A pair of NaI(Tl) detectors and a measurement and navigation frame ensuring loader shovel fixation in counting position are used for the fast sorting monitoring. The navigation of loader and its shovel to the counting geometry should be as fast as possible. The monitored results shall be indicated by a prompt light indication system (apart from storing on HDD). MCNP 5 calculation code was used for assessment of gross gamma 137Cs detection efficiency. The estimated MDA for a pair of 2″ × 2″ Na(Tl) detectors and 30 s acquisition time is about 90 Bq/kg. However, due to the counting geometry deviations from calculated values the uncertainty of measurements can be relatively high. Hence, the system is applicable for sorting monitoring only.

Uncertainty Analysis of Activity Measurement of New Monitoring System for Free-Release for NPP A-1 Decommissioning, Slovakia

2011 ◽  
Author(s):  
Alojz Slaninka ◽  
Ondrej Sla´vik ◽  
Vladimi´r Necˇas
Keyword(s):  
Uncertainty Analysis ◽  
Monitoring System ◽  
Detection Efficiency ◽  
Activity Measurement ◽  
Counting Geometry ◽  
Rectangular Container ◽  
Energy Peak ◽  
Hpge Detectors ◽  
Detector Characterization

New free release monitoring post with a large volume 600 L container counting geometry was designed and developed. The monitoring system is able to monitor a material also in standard counting geometry of 200 L drum. Using counting geometry of 600 L rectangular container that is equipped with self-discharger is able to increase the total monitoring capacity. The monitoring system is based on a pair of electrically cooled semiconductor HPGe detectors that are placed into a modifiable vertical or horizontal pair of lead collimators. The monitoring system is integrated with an industrial scale for determination of massic activities of measured materials and in addition by a rotating table in the case of 200 L drums monitoring. Monitoring system is integrated into transportable ISO container with constant environmental conditions that are ensured by air-condition unit. Full-energy peak detection efficiency (FPE) polynomial curves for various densities of measured material were in both cases determined by ISOCS calibration code based on designed counting geometry and delivered ISOCS/LabSOCS detector characterization. Uncertainty analysis of massic activity measurement by container and drum monitoring system in designed counting geometry is introduced below in more detail.

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