|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1990 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1989 : ¥2,100,000 (Direct Cost : ¥2,100,000)
The purposes of this research are (1) development of monochromatic neutron beams, being capable for the studies in nuclear spectroscopy and reaction dynamics in the En - 40 MeV region, and (2) study of spin-isospin excitation by the (n, p) reaction in nuclei, instead of the so far investigated (p, n) reaction. In order to realize such a difficult research with seconderly beams, emitted charged particles have been analyzed by a magnetic spectrometers equipped with a detector array, constructed in the present work. Also developed are data-taking and analyzing soft-wares.
We purchased isotonically enriched ^<6, 7>Li metal for the neutron production targets. The properties of neutron beams were tested using the neutron time-of-flight facilities located in Cyclotron and Radioisotope Center. With the neutron-beam production system including target, neutron collimator and beam stopper, we have obtained a neutron beam with its intensity of 5 x 10^<-6> /muA/sr, and with resolution of less than 7
00keV. (ref. 1) We have carried out the neutron scattering experiments in the course of this project. The 7Li target was bombarded by 37-MeV proton beams to produce 35-MeV neutron beams. Elastically and inelastically scattered neutrons by ^<28>Si were analyzed by the time-of-flight system. The angular distribution of scattering cross-section have been analyzed by the optical-model to investigate the core-polarization effects in the nuclear mean fields. (ref. 2) With the feasibility study of the (n, p) reaction, our final aim of this research is to study ^<12>C(n, p)^<12>B and ^<26>Mg(n, p)^<26>Na reactions. We have obtained preliminary results for the ^<12>C(n, p)^<12>B reaction. For the latter, however, we could not perform the experiment successfully, mainly due to its small cross-sections. A more intense proton beam of 100 muA is needed.
As a summary, we have constructed a monoenergetic fast-neutron facilities, which has sufficient specification for a neutron scattering experiment, though it needs more intense primary beams for the (n, p) reaction for heavier nuclei. Less