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Angular correlation measurements on the reaction ⁷Li(d, n∝)⁴He Heggie, John Cowan Philp


An experimental investigation of the sequential process ⁷Li(d, n∝)⁵He → ∝+ n was carried out at an energy of ~1.0 MeV. Neutron-alpha particle coincidences were measured with the neutron energy "being obtained from time of flight measurements. The results are presented in the form of neutron-alpha particle angular correlations. The lifetime of ⁵He lends support to the argument that the two stages of the reaction, the formation of ⁵He and its subsequent decay can be treated separately. Three possible reaction mechanisms have been considered for the first stage. It is expected that direct processes such as two and three particle transfer contribute very little to the yield at such a low bombarding energy. Certainly, calculations of the two-particle transfer amplitude using the formulism of DWBA are unable to fit the results. The most important reaction mechanism is shown to be compound nucleus formation through ⁹Be. In particular, in the neighbourhood of 1.0 MeV deuteron bombarding energy, the reaction proceeds largely by compound nucleus formation through the 17.28 MeV and 17.48 MeV levels of ⁹Be. The results suggest a spin and parity assignment of 5/2⁺ for the 17.48 MeV level and agree with a previous assignment of 5/2⁻ for the 17.28 MeV level.

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