Study of neutron induced charged particle reactions on 40K: (II). Resonance neutrons

doi:10.1016/0375-9474(81)90734-X

Nuclear Physics A

Volume 368, Issue 1, 21 September 1981, Pages 117-134

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Abstract

The ⁴⁰K(n, α)³⁷Cl and ⁴⁰K(n, p)⁴⁰Ar reaction cross sections were measured in the neutron energy region from 0.02 eV up to about 70 keV. The proton and α-particles were detected with a large surface barrier detector, and the neutron energy was measured by time of flight. The reaction cross sections show a pronounced resonance structure. A comparison of the density of s- and p-wave resonances (compound spins between $52$ and $112$ in ⁴⁰K + n to the density of spin − $52$ compound states observed as resonances in the reaction ⁴⁰Ar + p by Keyworth et al., allows a direct determination of the spin cut-off parameter of the level density.

References (8)

A. Emsallem et al.
Nucl. Phys.
(1981)
G.A. Keyworth et al.
Nucl. Phys.
(1966)
P.B. Parks et al.
Nucl. Phys.
(1966)
C.C. Lu et al.
Nucl. Phys.
(1972)

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Study of neutron induced charged particle reactions on 40K: (II). Resonance neutrons

Abstract

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Study of neutron induced charged particle reactions on ⁴⁰K: (II). Resonance neutrons