Nuclear Pair Emission from the 7.656-Mev Level in C12

David E. Alburger
Phys. Rev. 118, 235 – Published 1 April 1960
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Abstract

The 7.656-Mev nuclear pair transition from the 0+ second excited state of C12 has been observed in the Be9(α, n)C12 reaction by means of an intermediate-image pair spectrometer. With a beam of 5.81-Mev alpha particles incident on a 0.7-Mev thick Be foil target the observed intensity ratio of the 7.656-Mev pair line to the 4.433-Mev pair line from the 2+ first excited state of C12 was (5±1.5)×104. Approximately the same intensity ratio was found with both 5.38- and 5.81-Mev alpha particles incident on thick (6 mg/cm2) Be targets. By applying the appropriate factors for the spectrometer efficiency and for the internal pair conversion coefficient of the 4.433-Mev transition the derived ratio of pair to total widths of the 7.656-Mev level is Γe±Γ=8.2×107×R where R=N4.433N7.656, the ratio of neutron populations in the Be9(α, n)C12 reaction. As a rough estimate R is assumed to be ∼8 based on the only information available. This leads to Γe±Γ7×106 which is a factor of ∼15 smaller than estimates by Cook et al. in which the width Γα for the alpha-particle decay of the level was taken as 110 of the Wigner limit. The most plausible explanation of the data is that Γα is close to the Wigner limit.

  • Received 29 October 1959

DOI:https://doi.org/10.1103/PhysRev.118.235

©1960 American Physical Society

Authors & Affiliations

David E. Alburger*

  • Oak Ridge National Laboratory, Oak Ridge, Tennessee and Brookhaven National Laboratory, Upton, New York

  • *Permanent address, Brookhaven National Laboratory. This research was carried out at Oak Ridge National Laboratory while the author was a visitor during the summer of 1959.

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Vol. 118, Iss. 1 — April 1960

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