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Title: On Neutron-neutron Scattering in a DT Plasma

  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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DOE Contract Number:
Resource Type:
Technical Report
Country of Publication:
United States
Plasma Physics & Fusion Technology(70)

Citation Formats

Hayes, Anna C. On Neutron-neutron Scattering in a DT Plasma. United States: N. p., 2013. Web. doi:10.2172/1089460.
Hayes, Anna C. On Neutron-neutron Scattering in a DT Plasma. United States. doi:10.2172/1089460.
Hayes, Anna C. Mon . "On Neutron-neutron Scattering in a DT Plasma". United States. doi:10.2172/1089460.
title = {On Neutron-neutron Scattering in a DT Plasma},
author = {Hayes, Anna C},
abstractNote = {},
doi = {10.2172/1089460},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Aug 05 00:00:00 EDT 2013},
month = {Mon Aug 05 00:00:00 EDT 2013}

Technical Report:

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  • The approximations involved in computing range energy deposition of alpha particles in a DT plasma are discussed, and some numerical results are given. (auth)
  • The DT fusion neutron irradiation of 352 samples during 16 irradiation periods (beam-on time of more than 1219 hours) is described. Experiments from 16 individuals representing eight institutions are summarized. Maximum flux in any of the room temperature runs was 9 x 10'' neutrons/cm/sup 2/-sec for an 80 hour irradiation. The number of the UCID dosimetry reports detailing each of the irradiations are given.
  • A variety of elemental foils have been activated by neutron fluence from TFTR under conditions with the DT neutron yield per shot ranging from 10{sup 12} to over 10{sup 18}, and with the DT/(DD+DT) neutron ratio varying from 0.5% (from triton burnup) to unity. Linear response over this large dynamic range is obtained by reducing the mass of the foils and increasing the cooling time, all while accepting greatly improved counting statistics. Effects on background gamma-ray lines from foil-capsule-material contaminants, and the resulting lower limits on activation foil mass, have been determined. DT neutron yields from dosimetry standard reactions onmore » aluminum, chromium, iron, nickel, zirconium, and indium are in agreement within the {+-}9% (one-sigma) accuracy of the measurements; also agreeing are yields from silicon foils using the ACTL library cross-section, while the ENDF/B-V library has too low a cross-section. Preliminary results from a variety of other threshold reactions are presented. Use of the {sup 115}In(n.n{prime}) {sup 115m}In reaction (0.42 times as sensitive to DT neutrons as DD neutrons) in conjunction with pure-DT reactions allows a determination of the DT/(DD+DT) ratio in trace tritium or low-power tritium beam experiments.« less
  • Measurements were performed with a single annular, stainless-steel-canned casting of uranium (93.17 wt% 235U) metal ( ~18 kg) to provide data to verify calculational methods for criticality safety. The measurements used a small portable DT generator with an embedded alpha detector to time and directionally tag the neutrons from the generator. The center of the time and directional tagged neutron beam was perpendicular to the axis of the casting. The radiation detectors were 1x1x6 in plastic scintillators encased in 0.635-cm-thick lead shields that were sensitive to neutrons above 1 MeV in energy. The detector lead shields were adjacent to themore » casting and the target spot of the generator was about 3.8 cm from the casting at the vertical center. The time distribution of the fission induced radiation was measured with respect to the source event by a fast (1GHz) processor. The measurements described in this paper also include time correlation measurements with a time tagged spontaneously fissioning 252Cf neutron source, both on the axis and on the surface of the casting. Measurements with both types of sources are compared. Measurements with the DT generator closely coupled with the HEU provide no more additional information than those with the Cf source closely coupled with the HEU and are complicated by the time and directionally tagged neutrons from the generator scattering between the walls and floor of the measurements room and the casting while still above detection thresholds.« less
  • A series of calibration experiments has been done to characterize an NE-213 liquid scintillator detector of photons ranging up to approx.7 MeV. Calibrated sources of /sup 24/Na, /sup 22/Na, /sup 60/Co, and /sup 137/Cs were used to infer the conversion factors as a function of electron energy, and detector efficiencies. In the latter effort, comparisons were made of the measured electron recoil spectra with their calculated counterpart. The code SANDYL was used and its results were modified slightly by folding in a normal distribution to account for the anticipated broadening due to variations in the location of light pulses withinmore » the scintillator. The calculated spectra were 0 to 10% above the experimental data. Higher energy gamma rays were generated by a Pu-Be source, which generated the 4.439-MeV line from /sup 12/C*, and the /sup 16/O(n,n')/sup 16/O* reaction, which generated among others the 6.130, 6.919, and 7.117 lines. We observed a marked nonlinearity of light pulse amplitude with electron energy at higher energies. Linearity was confirmed at and below 2.75 MeV, with an estimated threshold at 15 keV. The nonlinearity at higher energy will complicate the analysis.« less