This work is concerned with a theoretical and experimental investigation of pulsed neutron beams used in elemental <i>in vivo</i> analysis. The main object of the theoretical work is to develop a Monte Carlo simulation programme to study the history of the incident deuteron beam on the deuterated titanium target in the Van de Graaff neutron generator used as a neutron source for <i>in vivo</i> analysis. Experimental measurements are reported for a 5 x 2.5 cm organic liquid scintillator NE-213 as a neutron detector after the spectrometer was systematically calibrated, using a new technique, to determine the parameters used in the unfolding programme. The angular distributions and the background contribution of the neutrons produced by the Van de Graaff generator were measured at three different angles (0<SUP>o</SUP>, 45<SUP>o</SUP> and 90<SUP>o</SUP>) under the same conditions as those used in the theoretical study. A small neutron spectrometer was designed and constructed, using a 1 x 1 cm organic liquid scintillator cell and a new photomultiplier tube which approximately matches the small cell cross-section. This detector was tested and its gain measured experimentally at two different voltages. The results showed good discrimination between short (gamma-ray) and long (neutron) pulses, but the gain was not large enough for accurate calibration. The theoretical results showed good agreement with the experimental measurements and with previous work, but showed a small number of additional neutrons in the higher energy ranges. This occurred since the scattering angle of the incident deuteron in the target was allowed for in the computations. The dose equivalent of the neutron beam was computed from the experimental energy spectrum and was in good agreement with the result obtained under the same conditions using the neutron dosimeter.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637359 |
| Date | January 1991 |
| Creators | Hussen, T. A.-L. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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