ABSTRACT
Aiming at increasing the count rate capability of the radial neutron collimator system in JT-60U, a digital-signal processing system has been extended to seven channels for data acquisition of stilbene crystal detector using analog-to-digital converters equipped with a fast flash memory. In this method, the detected pulses were postprocessed concerning pulse shape and pulse height. Using this system, the radial neutron collimator system can provide the information on the temporal evolution of emission rate of d-T neutrons and gamma rays as well as d-D neutrons. On the course of the development, the fast and stable handling of the large data around 7 GB is undertaken for a discharge.
ABSTRACT
The use of the parallel-plate avalanche counter for slow-neutron counting is described. The choice of a suitable neutron converter is discussed on the basis of Monte Carlo simulation, and some experimental results are shown. Excellent gamma-insensitivity, high rate capability, possibility of construction in large sensitive area and low production cost are among the promising features of this neutron detector.
Subject(s)
Gamma Rays , Monte Carlo Method , Neutron Activation Analysis/instrumentation , Neutron Activation Analysis/methods , Neutrons , Radiometry/instrumentation , Computer Simulation , Humans , Models, Biological , Radiometry/methodsABSTRACT
The stilbene neutron detector which has been used for neutron emission profile monitoring in JT-60U has been improved, to respond to the requirement to observe the high-frequency phenomena in megahertz region such as toroidicity-induced Alfvén Eigen mode in burning plasma as well as the spatial profile and the energy spectrum. This high-frequency phenomenon is of great interest and one of the key issues in plasma physics in recent years. To achieve a fast response in the stilbene detector, a Flash-ADC is applied and the wave form of the anode signal stored directly, and neutron/gamma discrimination was carried out via software with a new scheme for data acquisition mode to extend the count rate limit to MHz region from 1.3 x 10(5) neutron/s in the past, and confirmed the adequacy of the method.
Subject(s)
Analog-Digital Conversion , Neutrons , Nuclear Reactors/instrumentation , Occupational Exposure/analysis , Radiation Monitoring/instrumentation , Radiation Protection/instrumentation , Stilbenes/radiation effects , Equipment Design , Equipment Failure Analysis , Nuclear Fusion , Radiation Dosage , Radiation Monitoring/methods , Radiation Protection/methods , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
Experimental differential cross sections of fragment emission (p, d, t, alpha, Li, Be and B), which were obtained for tens of mega electron volt neutrons on carbon and aluminum, using a counter telescope array and a Bragg-curve counter specially developed for neutron-induced reactions, are presented and compared with theoretical calculations using various reaction models. A calculation with the ISOBAR and GEM models was found to reproduce the experimental data except for an underestimation in non-vaporation processes. Calculations of the energy deposition by neutrons in a thin silicon layer show significant differences among the model employed.
