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ENERGY SPECTRA AND ANGULAR DEPENDENCES OF NEUTRONS FROM THE 31.5-MEV PROTON BOMBARDMENT OF BERYLLIUM-9, NITROGEN-14, AND ALUMINUM-27 (thesis)

Technical Report ·
OSTI ID:4258430
The energy spectra and absolute differential cross seetions of neutrons of energy greater than 5 Mev emitted from thin targets of beryllium, nitrogen (melamine), and aluminum bombarded by 31.5-Mev protons were measurnd at tbrce angles (53. 90, and 127 deg ). The 4-in. hydrogen bubble chamber was used as a neutron spectrometer. A fast data-reduction system for the analysis of the recoil-proton tracks was developed utilizing a commercial electronic coordinate- measuring device, the IBM punch-card system, and the IBM 650 digital computer. The resolution of the entire spectrometer syatem was determined by measuring the monoergic (14.1-Mev) neutron spectrum from the T(d,n)He/sup 4/ reaction. The full width at haIf marimum of the measured peak was 10% of the peak energy. The energy spectra from the beryllium and nitrogen bombardments contnined structure that may correspond to levels in the residual nuclei of the Be/sup 9/(p,n)Be/sup 9/ and N/sup 14/(p,n)O/sup 14/ reactions. Poor statistics did not permit definite level assignments, but several of the possible levels of B/sup 9/ correspond to known levels of its mirror nucleus, Be/sup 9/. The angular dependence of the neutron production above 5 Mev from all three targets shows a forward asymmetry. The production from aluminum, which was the heaviest target bombarded. and for which the neutronproduction mechanism might be expected to be the compound model, was in a ratio of 5:3:2 for 53, 90, and 127 deg (lab), respectively. This forward asymmetry is not to be expected from the compound model, and appears to indicate a predominance of the direct-interaction mechanism for the higher-energy neutrons. (auth)
Research Organization:
California. Univ., Berkeley. Lawrence Radiation Lab.
DOE Contract Number:
W-7405-ENG-48
NSA Number:
NSA-13-007875
OSTI ID:
4258430
Report Number(s):
UCRL-8568
Country of Publication:
United States
Language:
English