Digitized two parameter spectrometer for neutron gamma mixed field

This paper shows the results of digital processing of output pulses from combined photon-neutron detector using a commercially available digitizer ACQUIRIS DP 210. The advantage of digital processing is reduction of the apparatus in weight and size, acceleration of measurement, and increased resistance to pile-up of pulses. The neutron and photon spectrum of radionuclide source 252Cf is presented.Tento článek pojednává o digitálním zpracování dat poskytovaných detektorem směsného neutronového a gama záření pomocí komerčně dostupného digitizéru ACQUIRIS DP 210. Výhodou digitálního zpracování je snížení hmotnosti a rozměrů měřicí aparatury, zrychlení měření a zvýšená odolnost vůči superpozici jednotlivých impulzů. Funkce navržené metody je doložena energetickým spektrum neutronů a fotonů vyzařovaných 252Cf.This paper shows the results of digital processing of output pulses from combined photon-neutron detector using a commercially available digitizer ACQUIRIS DP 210. The advantage of digital processing is reduction of the apparatus in weight and size, acceleration of measurement, and increased resistance to pile-up of pulses. The neutron and photon spectrum of radionuclide source 252Cf is presented

Digitized Two-Parameter Spectrometer for Neutron-Gamma Mixed Field

This paper shows the results of digital processing of output pulses from combined photon-neutron detector using a commercially available digitizer ACQUIRIS DP 210. The advantage of digital processing is reduction of the apparatus in weight and size, acceleration of measurement, and increased resistance to pile-up of pulses. The neutron and photon spectrum of radionuclide source 252Cf is presented.Tato práce ukazuje výsledky digitálního zpracování výstupních impulsů detektoru směsného pole fotonů a neutronů pomocí komerčně dostupného digitizéru ACQUIRIS DP 210. Výhodou digitálního zpracování je snížení rozměrů a hmotnosti technického vybavení, zrychlení měření a zvýšená odolnost proti superpozici pulsů. Experimenty jsou prezentovány na směsném záření neutronů a gama záření radionuklidu 252Cf.This paper shows the results of digital processing of output pulses from combined photon-neutron detector using a commercially available digitizer ACQUIRIS DP 210. The advantage of digital processing is reduction of the apparatus in weight and size, acceleration of measurement, and increased resistance to pile-up of pulses. The neutron and photon spectrum of radionuclide source 252Cf is presented

Detection of mixed fields of neutron and photon radiation using 3He and new scintillation materials

The poster includes experimental measurements with 3He and the latest scintillation materials EJ-299-33 in fields of neutron and photon radiation using modern electronics which we designed. Electronic part of the measuring system is built on recently developed AD converter with very high sampling frequency (1 GHz). In the theoretical part, the Monte Carlo simulations of response characteristics of the measured scintillation materials are presented.Poster obsahuje experimentální měření za požití He-3 a nejnovějšího scintilačního materiálu EJ-299-33 v polích neutronů a fotonů. Elektronická část je postavena na základě velmi rychlých AD převodnků (1 GHz). V teoretické části je popsána Monte Carlo simulace odezvové matice použitých detektorů.The poster includes experimental measurements with 3He and the latest scintillation materials EJ-299-33 in fields of neutron and photon radiation using modern electronics which we designed. Electronic part of the measuring system is built on recently developed AD converter with very high sampling frequency (1 GHz). In the theoretical part, the Monte Carlo simulations of response characteristics of the measured scintillation materials are presented

Digitalized two parametric system for gamma/neutron spectrometry

Many types of detectors like stilbene, NE-213 etc. in conjunction with photomultiplier loaded with low working resistance produce pulses of approximately 100 ns length and contain information about deposited particle in the trailing edge. Using fast analog to digital converters (ADC) and field-programmable gate array (FPGA) it is possible to create a spectrometric system working in mixed gamma and neutron fields which is not loaded dead time. The count rate of processed pulses can reach more than one million per second. Such a high count rate of processed pulses can be achieved due to the pulse processing is implemented in FPGA. The output of this pulse processing is amplitude which describes the energy of deposited particle and discrimination parameter whereby it is possible to discriminate photons and neutrons. To increase the dynamic range of energy of detectable particle the signal from photomultiplier is separated into two branches with different amplification. Each branch is digitalized by separate ADC. Components from which the system is composed are so light that the spectrometer can be easily transported. Its weight is less than 3 kilograms. Spectrometer was tested in the research reactor LR-0 in Rez near Prague (Czech Republic). The measured data was processed using deconvolution into a neutron flux density and compared with nowadays used analog spectrometer and simulation result. Measured neutron spectrum of Cf-252 is included.Článek popisuje spektrometr pro měření ve směsných polích gama/neutrony. Analogový signál z detektoru je vzorkován AD převodníky pracujícími na frekvenci 1 GHz. Předzpracování signálu probíhá v FPGA a tím je zajištěna vysoká propustnost systému bez mrtvé doby. Spektrometr byl testován v Centru výzkumu Řež na reaktoru LR-0.Many types of detectors like stilbene, NE-213 etc. in conjunction with photomultiplier loaded with low working resistance produce pulses of approximately 100 ns length and contain information about deposited particle in the trailing edge. Using fast analog to digital converters (ADC) and field-programmable gate array (FPGA) it is possible to create a spectrometric system working in mixed gamma and neutron fields which is not loaded dead time. The count rate of processed pulses can reach more than one million per second. Such a high count rate of processed pulses can be achieved due to the pulse processing is implemented in FPGA. The output of this pulse processing is amplitude which describes the energy of deposited particle and discrimination parameter whereby it is possible to discriminate photons and neutrons. To increase the dynamic range of energy of detectable particle the signal from photomultiplier is separated into two branches with different amplification. Each branch is digitalized by separate ADC. Components from which the system is composed are so light that the spectrometer can be easily transported. Its weight is less than 3 kilograms. Spectrometer was tested in the research reactor LR-0 in Rez near Prague (Czech Republic). The measured data was processed using deconvolution into a neutron flux density and compared with nowadays used analog spectrometer and simulation result. Measured neutron spectrum of Cf-252 is included

Quick algorithms for real-time discrimination of neutrons and gamma rays

Several new methods for the digital discrimination of neutrons and gamma-rays in a mixed radiation field are presented. The methods introduced discriminate neutrons and gamma rays successfully in the digital domain. They are mathematically simple and exploit samples during the life time of the pulse, hence appropriate for field measurements. All these methods are applied to a set of mixed neutron and photon signals from a stilbene scintillator and their discrimination qualities are compared.V článku je prezentováno několik nových metod pro digitální diskriminace neutronů a gama záření ve směsném radiačním poli. Klasické metody diskriminace neutronů a gama záření pracují úspěšně v digitální doméně. Jsou matematicky jednoduché a využívat vzorků během doby trvání impulsu (odezvy) a jsou tedy vhodné pro měření v terénu. Všechny tyto metody jsou aplikovány na řadu odezev smíšených polí neutronového a fotonového záření ze scintilátoru typu stilben a jejich separační vlastnosti jsou porovnány.Several new methods for the digital discrimination of neutrons and gamma-rays in a mixed radiation field are presented. The methods introduced discriminate neutrons and gamma rays successfully in the digital domain. They are mathematically simple and exploit samples during the life time of the pulse, hence appropriate for field measurements. All these methods are applied to a set of mixed neutron and photon signals from a stilbene scintillator and their discrimination qualities are compared

Benchmarking of stainless steel cube neutron leakage in Research Center Rez

The integral experiments covering the neutron leakage from geometrically simple assemblies with a 252Cf source inside are very valuable tools usable in validation of transport cross section data, since geometric uncertainties play a much smaller role in simple geometric assemblies than in complex assemblies as for example reactor pressure vessel geometry. Since 252Cf(s.f.) is standard neutron source, the uncertainties connected with the source neutron spectrum can be even neglected. The paper refers on validation efforts of neutron leakage from stainless steel block ~50 x 50 x50 cm in Research Center Rez. Both the neutron leakage flux at a distance of 1 m from the center of the cubical assembly using stilbene spectrometry and the activation rates at different positions of the assembly were evaluated. In addition to experiments, main sources of uncertainty were identified and evaluated. The results of the stilbene measurements are consistent with the activation measurements results

The effect of the aging of liquid organic scintillators used for gamma-neutron separation

Since the beginning of using liquid scintillators for gamma-neutron separation, there have been many articles dealing with long-term degradation especially due to oxygen presented during scintillator encapsulation. The effect of aging of liquid organic scintillators namely EJ301, EJ309 (both Eljen Technology), and new custom-made cocktails based on 1-Phenyl-3-(2,4,6-trimethylphenyl)-2-pyrazoline and 2,5-Bis(5-tert-butyl-benzoxazol-2-yl)thiophene fluors were investigated for more than half a year. The research was focused on the Compton edge shifting of gamma particles since the position is proportional to the light yield of the selected scintillator. Furthermore, the gamma-neutron separation was observed and quantified using FOM (Figure Of Merit) for samples prepared and filled under normal and nitrogen atmosphere during the mentioned period. All stated parameters of liquid scintillator NE213 manufactured by Nuclear Enterprises Limited opened more than three decades ago were measured and used for comparison

Measurement and simulation of the new liquid organic scintillator response to fast neutrons

Liquid organic scintillators are important devices for measurements of neutron radiation. This work aims to develop and optimize the composition of liquid organic scintillators so it can be used for fast neutron spectrometry. As the neutron radiation is usually accompanied with γ ray radiation, it is important to have quality γ/n discrimination. The new cocktail for house made liquid organic scintillator is prepared and studied with intention of being able to separate gamma and neutron for neutron energies above 0.5 MeV while keeping lower constraints on practical use (e.g., sealing because of oxygen) than commercial liquid scintillators. In preceding work the composition of liquid scintillators was optimized. Two twocomponent scintillators were selected for further studies. Solvent DIPN (Di-iso-propyl-naphthalene Mixed Isomers) is selected for both. First is mixed with luminophore PYR (1-Phenyl-3-(2,4,6-trimethyl-phenyl)-2-pyrazoline) of concentration 5 g/l. Second is mixed with luminophore THIO (2,5-Bis(5-tert-butyl-benzoxazol-2-yl)thiophene) of concentration 5 g/l. In this work the response of scintillator to monoenergetic beam of neutrons was measured for multiple neutron energies at PTB in Braunschweig. The two parameter spectrometric system NGA-01 is used to analyze the energy and discrimination characteristics. 137 Cs and 60 Co are used as radiation sources for calibration with pure γ rays. Then the response of scintillator for same neutron energies was simulated using GEANT4. The dissipated energy in the scintillator in response to monoenergetic neutrons is obtained. Both, measured and simulated responses are compared. Functional dependence for yield of recoiled products is estimated. It is seen that main recoil product hydrogen proton is well observed in both. From the edge of proton response one can assume the yield for given neutron energy. The recoiled carbon ion (from elastic collision) is on the other side difficult to observe in measured results but clearly seen in dissipated energy plots. It suggests that yield of carbon ion is very small relatively to proton yield. These results will serve as basis for response function evaluation of scintillator which is necessary for evaluation of unknown neutron spectra from measurements with scintillator

Digital two-parametric processing of the output data from radiation detectors

In this paper, we present the results of digital processing of pulses produced by several types of detectors. We introduce a new high quality discrimination method, and the output from this new method is compared with those from classic methods. Also, a new function to determine separation quality of various discrimination methods is defined in this paper. Our results show how the quality of the particle type identification depends on the sampling rate as well as the method of sampled data processing