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Title: Comparison Between Digital and Analog Pulse Shape Discrimination Techniques For Neutron and Gamma Ray Separation

Abstract

Recent advancement in digital signal processing (DSP) using fast processors and computer makes it possible to be used in pulse shape discrimination applications. In this study, we have investigated the feasibility of using a DSP to distinguish between the neutrons and gamma rays by the shape of their pulses in a liquid scintillator detector (BC501), and have investigated pulse shape-based techniques to improve the resolution performance of room-temperature cadmium zinc telluride (CZT) detectors. For the neutron/gamma discrimination, the advantage of using a DSP over the analog method is that in analog system two separate charge-sensitive ADC's are required. One ADC is used to integrate the beginning of the pulse risetime while the second ADC is for integrating the tail part. Using a DSP eliminates the need for separate ADCs as one can easily get the integration of two parts of the pulse from the digital waveforms. This work describes the performance of these DSP techniques and compares the results with the analog method.

Authors:
;
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
USDOE
OSTI Identifier:
911616
Report Number(s):
INL/CON-05-00284
TRN: US0800043
DOE Contract Number:
DE-AC07-99ID-13727
Resource Type:
Conference
Resource Relation:
Journal Volume: 1; Conference: IEEE Nuclear Science Symposium,Puerto Rico,10/23/2005,10/30/2005
Country of Publication:
United States
Language:
English
Subject:
46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ANALOG SYSTEMS; CADMIUM; COMPUTERS; LIQUID SCINTILLATORS; NEUTRONS; PERFORMANCE; PROCESSING; RESOLUTION; SHAPE; WAVE FORMS; ZINC TELLURIDES; Gamma rays; Neutron; Radiation detection

Citation Formats

R. Aryaeinejad, and John K. Hartwell. Comparison Between Digital and Analog Pulse Shape Discrimination Techniques For Neutron and Gamma Ray Separation. United States: N. p., 2005. Web. doi:10.1109/NSSMIC.2005.1596302.
R. Aryaeinejad, & John K. Hartwell. Comparison Between Digital and Analog Pulse Shape Discrimination Techniques For Neutron and Gamma Ray Separation. United States. doi:10.1109/NSSMIC.2005.1596302.
R. Aryaeinejad, and John K. Hartwell. Tue . "Comparison Between Digital and Analog Pulse Shape Discrimination Techniques For Neutron and Gamma Ray Separation". United States. doi:10.1109/NSSMIC.2005.1596302. https://www.osti.gov/servlets/purl/911616.
@article{osti_911616,
title = {Comparison Between Digital and Analog Pulse Shape Discrimination Techniques For Neutron and Gamma Ray Separation},
author = {R. Aryaeinejad and John K. Hartwell},
abstractNote = {Recent advancement in digital signal processing (DSP) using fast processors and computer makes it possible to be used in pulse shape discrimination applications. In this study, we have investigated the feasibility of using a DSP to distinguish between the neutrons and gamma rays by the shape of their pulses in a liquid scintillator detector (BC501), and have investigated pulse shape-based techniques to improve the resolution performance of room-temperature cadmium zinc telluride (CZT) detectors. For the neutron/gamma discrimination, the advantage of using a DSP over the analog method is that in analog system two separate charge-sensitive ADC's are required. One ADC is used to integrate the beginning of the pulse risetime while the second ADC is for integrating the tail part. Using a DSP eliminates the need for separate ADCs as one can easily get the integration of two parts of the pulse from the digital waveforms. This work describes the performance of these DSP techniques and compares the results with the analog method.},
doi = {10.1109/NSSMIC.2005.1596302},
journal = {},
number = ,
volume = 1,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}

Conference:
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  • Recent advancements in digital signal processing (DSP) using fast processors and a computer allows one to envision using it in pulse shape discrimination. In this study, we have investigated the feasibility of using a DSP to distinguish between neutrons and gamma rays by the shape of their pulses in a liquid scintillator detector (BC501). For neutron/gamma discrimination, the advantage of using a DSP over the analog method is that in an analog system, two separate charge-sensitive ADCs are required. One ADC is used to integrate the beginning of the pulse rise time while the second ADC is for integrating themore » tail part. In DSP techniques the incoming pulses coming directly from the detector are immediately digitized and can be decomposed into individual pulses waveforms. This eliminates the need for separate ADCs as one can easily get the integration of two parts of the pulse from the digital waveforms. This work describes the performance of these DSP techniques and compares the results with the analog method.« less
  • A fast and stable digital pulse-shape discriminating unit has been developed for the moisture gauge using /sup 252/Cf as radiation source. This unit performs digital discrimination between neutrons and gamma-rays in conbination with the liquid scintillator NE213. Modern digital integrated circuits such as flash type A-D converter, a digital divider, a digital comparator and digital controlled gated integrators compose the discrimination circuit. Neutrons and gamma-rays events are separately accumulated and applied for automatic stabilization by an integrated single-chip computer. The discriminating characteristics are controlled not only manually but also under a host computer by way of the GPIB. The performancesmore » of available event rates and long term stability are estimated around 100 kcps and 0.5 % respectively. The actual circuit configuration and features are discussed in detail.« less
  • Cited by 5
  • A comparison study of pulse-shape analysis techniques was conducted for a BC501A scintillator using digital signal processing (DSP). In this study, output signals from a preamplifier were input directly into a 1 GHz analog-to-digital converter. The digitized data obtained with this method was post-processed for both pulse-height and pulse-shape information. Several different analysis techniques were evaluated for neutron and gamma-ray pulse-shape discrimination. It was surprising that one of the simplest and fastest techniques resulted in some of the best pulse-shape discrimination results. This technique, referred to here as the Integral Ratio technique, was able to effectively process several thousand detectormore » pulses per second. This paper presents the results and findings of this study for various pulse-shape analysis techniques with digitized detector signals.« less
  • A new neutron multiplicity counter is being developed which utilizes the fast response of liquid scintillator (NE-213) detectors. Current uranium coincidence counting methods rely on the assay samples to conform to the calibration standards with respect to the sample uniformity, geometry, material type, etc. There exists a wide range of material throughout the DOE complex where these attributes are non-standard or unknown. A neutron counter with short die-away time makes possible the measurement of higher order coincidences. This information can be used to more accurately assay many of the problem items in the inventory. In addition, such a counter wouldmore » allow for rapid inventory measurements of all forms of uranium. Liquid scintillator detectors also allow for energy discrimination between interrogation source neutrons and fission neutrons, allowing for even greater assay sensitivity. Liquid scintillator detectors are sensitive to {gamma} and neutron radiation. Differences in the timing of scintillation light produced in {gamma}-ray and neutron interactions allows for separation of these events using pulse shape discrimination (PSD). PMT pulses resulting from neutron and {gamma} interactions in the Liquid scintillator are read in using a fast waveform digitizer with a 1 GS/s sampling rate. The pulse shapes are then compared to {gamma} and neutron pulse templates and a {chi}{sup 2} comparison determines the species. Integrated rise time can also be used to discriminate between they and neutron pulses. The results of these studies are presented.« less