THE COSINE-CUBED NEUTRON SPECTROMETER (thesis)

In an attempt to increase the efficiency, a proton recoil neutron spectrometer was built in which the proton detection crystal is in the shape of the surface formed by the rotation of the cos/sup 3/ THETA curve about the THETA = 0 axis where THETA is the angle between the direction of travel of the incident neutron and the direction of travel of the recoil proton. Such a construction makes the detector crystal conform to the range envelope of the protons recoiling from a neutron beam of sufficiently high energy into a gas in which the proton range is proportional to the 3/2 power of the proton energy. Sixteen pieces of thallium-activated cesium iodide were assembled as a mosaic arranged in the cos/sup 3/ THETA shape so that the maximum THETA was 30 deg . Calculations show that 25% of the protons recoil within 30 deg . The Po-Be snd Po-B spectra were measured with the instrument using xenon in the chamber. The resolution of the spectra obtained was low due to nonuniform pulse height response of the CsI crystal sections and excessive gamma-ray response even though sn anthracene proton radiator was used in a coincidence scheme designed to minimize gamma-ray background. The instrument did not exhibit the added efficiency which was being sought in the design. The necessity of single chamel operation further limits its usefulness. (auth