Elsevier

Nuclear Physics A

Volume 334, Issue 1, 28 January 1980, Pages 127-143
Nuclear Physics A

Preequilibrium α-particle emission in heavy-ion reactions

https://doi.org/10.1016/0375-9474(80)90144-XGet rights and content

Abstract

The α-particle emission following 14N-induced reactions on various heavy targets at 85–115 MeV has been studied. Cross sections of heavy residual nuclei produced after α-emission were measured in the case of the 209Bi target and were found to be close to the angle-integrated cross sections of α-particles, indicating that the α-emission mainly takes place in a binary process. The measured angular distributions of α-particles are pronouncedly forward-peaked, while the energy spectra are always characterized by the Maxwellian distribution even at forward angles and reproduced excellently by the statistical evaporation formula when nuclear temperature is treated as a free parameter. The resultant value of the temperature is high (4–6 MeV) at forward angles and decreases monotonically with increasing emission angles.

The energy and angular distributions of protons, deuterons and tritons were also measured in the 181Ta + 14N reaction at 115 MeV. The results are similar to those of α-particles. In particular, nuclear temperatures turned out nearly equal to each other, being consistent with the hot-spot interpretation for the relevant preequilibrium light-particle emission.

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    Permanent address: Department of Physics, Kyoto University, Kyoto, Japan.

    ††

    Permanent address: Deparment of Physics, Tokyo Institute of Technology, Meguroku, Tokyo.

    Permanent address: Deparment of Physics, Osaka University, Toyonaka, Osaka, Japan.

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