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Title: Neutron Inelastic Scattering Mechanism and Measurement of Neutron Asymmetry Using Time of Flight Technique

Abstract

Inelastic scattering is an essential reaction for other nuclear reactions to detect the optical model and compound nucleus formation within the range of (0.4- 5.0) MeV neutron incident energy by using time of flight technique. The time of flight system (TOFS) installed on the horizontal channel reactor RRA has been used to measure the asymmetry of scattered fast neutrons, when data acquisition and system control were recorded event by event by HP - computer via CAMAC system. Eight NE 213 neutron counters were used in order to detect neutron inelastic scattering in the forward direction (4 neutron counters at 0 deg. angle) and in the backward direction (4 neutron counters at 180 deg. angle) to measure the asymmetry of fast neutron. Each neutron counter was 50cm in length and 8cm in diameter, viewed by two (58 - DVP) photomultiplier tubes. The contribution of direct interaction to the compound nucleus formation was deduced from the asymmetry in the neutron detection at the same direction of these eight neutron counters. A time resolution of 8.2 ns between the eight neutron counters and one of the two Ge(Li) detectors has been obtained.

Authors:
 [1]
  1. Nuclear Energy Center (Argentina)
Publication Date:
OSTI Identifier:
21054902
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 888; Journal Issue: 1; Conference: MTPR-06: 2. international conference on modern trends in physics research, Cairo (Egypt), 6-11 Apr 2006; Other Information: DOI: 10.1063/1.2711121; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ASYMMETRY; CAMAC SYSTEM; COMPOUND NUCLEI; COMPOUND-NUCLEUS REACTIONS; DATA ACQUISITION; DATA ACQUISITION SYSTEMS; FAST NEUTRONS; INELASTIC SCATTERING; LI-DRIFTED GE DETECTORS; MEV RANGE; NEUTRON DETECTION; OPTICAL MODELS; PHOTOMULTIPLIERS; SYMMETRY; TIME RESOLUTION; TIME-OF-FLIGHT METHOD

Citation Formats

Al Azzawe, A. J. M.. Neutron Inelastic Scattering Mechanism and Measurement of Neutron Asymmetry Using Time of Flight Technique. United States: N. p., 2007. Web. doi:10.1063/1.2711121.
Al Azzawe, A. J. M.. Neutron Inelastic Scattering Mechanism and Measurement of Neutron Asymmetry Using Time of Flight Technique. United States. doi:10.1063/1.2711121.
Al Azzawe, A. J. M.. Wed . "Neutron Inelastic Scattering Mechanism and Measurement of Neutron Asymmetry Using Time of Flight Technique". United States. doi:10.1063/1.2711121.
@article{osti_21054902,
title = {Neutron Inelastic Scattering Mechanism and Measurement of Neutron Asymmetry Using Time of Flight Technique},
author = {Al Azzawe, A. J. M.},
abstractNote = {Inelastic scattering is an essential reaction for other nuclear reactions to detect the optical model and compound nucleus formation within the range of (0.4- 5.0) MeV neutron incident energy by using time of flight technique. The time of flight system (TOFS) installed on the horizontal channel reactor RRA has been used to measure the asymmetry of scattered fast neutrons, when data acquisition and system control were recorded event by event by HP - computer via CAMAC system. Eight NE 213 neutron counters were used in order to detect neutron inelastic scattering in the forward direction (4 neutron counters at 0 deg. angle) and in the backward direction (4 neutron counters at 180 deg. angle) to measure the asymmetry of fast neutron. Each neutron counter was 50cm in length and 8cm in diameter, viewed by two (58 - DVP) photomultiplier tubes. The contribution of direct interaction to the compound nucleus formation was deduced from the asymmetry in the neutron detection at the same direction of these eight neutron counters. A time resolution of 8.2 ns between the eight neutron counters and one of the two Ge(Li) detectors has been obtained.},
doi = {10.1063/1.2711121},
journal = {AIP Conference Proceedings},
number = 1,
volume = 888,
place = {United States},
year = {Wed Feb 14 00:00:00 EST 2007},
month = {Wed Feb 14 00:00:00 EST 2007}
}
  • A new experimental technique for obtaining time-of-flight spectra of a scattered molecular beam is reported. Both the primary (K) and the secondary (NH/sub 3/) beam were velocity selected and had very narrow angular spreads, resulting in high-resolution TOF spectra. Both beams had thermal energy, and the TOF spectra of the scattered potassium atoms were obtained at five different LAB angles and four different primary beam velocities. The spectra show that more than 50% of the scattering is inelastic. The mean energy transfer ranges between 15.6 and 40.4 meV, which corresponds to about 20%--40% of the relative total kinetic energy. Themore » inelastic scattering is due to rotational excitation of NH/sub 3/. A modified hard-sphere model for this process leads to an average angular momentum transfer of 2-3 h-bar. The effect of the long-range potential is discussed.« less
  • No abstract prepared.
  • A time-of-flight spectrometer utilizing a magnetically pulsed beam has been placed in operation at the High Flux Isotope Reactor at the Oak Ridge National Laboratory. The pulsing is accomplished by rapidly changing the magnetic moment direction in a ferrite crystal that serves to both monochromate and pulse the beam. Good neutron reflectivity is obtained from the ferrite crystal and pulse risetimes of the order of 1 μs are available. The spectrometer is interfaced to a Digital Equipment Corporation PDP-15-30 computer which drives pulsed motors to set up the desired scattering geometry and collects and analyzes the time-of-flight data. The magneticallymore » pulsed beam is ideal for use with the cross-correlation technique and spectra are presented which show the accuracy of the pulsing technique and the power of the cross correlation methods in obtaining neutron scattering data.« less