Structure in the excitation functions of (3He, α) reactions on a number of alpha-type nuclei

doi:10.1016/0375-9474(69)90609-5

Nuclear Physics A

Volume 132, Issue 1, 14 July 1969, Pages 9-27

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Abstract

Excitation functions have been measured for the reactions ¹⁶O(³He, α)¹⁵O and ²⁸Si (³He, α²⁷Si over a bombarding energy range 4.0–9.0 MeV and for the reaction ²⁴Mg(³He, α) ²³Mg from 4.0–6.2 MeV. An analysis of the data using the statistical model of Ericson has been attempted, and coherence widths of 130±20 keV for ¹⁹Ne, 125±30 keV for ²⁷Si and 102±10 keV for ³¹S are found. The reactions appear to proceed predominantly by a direct mechanism. However the assumptions of the Ericson theory are not fully satisfied, since a wider structure is found in the experimental data. Possible interpretations of this structure are discussed.

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Structure in the total 27Al(n, α)24Na cross section around 14 MeV
1976, Nuclear Physics, Section A
An excitation function for the ²⁷Al(n, α) reaction has been measured in steps of about 15 keV throughout most of the energy range between 13.45 and 14.91 MeV in an effort to observe structure in the cross section. The insulated core transformer (ICT) neutron facility was used as the neutron source; a rotating, tritiated titanium target, capable of handling ion beams with currents up to 10 mA and with energies up to 450 keV, was employed. Using the activation method, a total of about 500 relative cross-section measurements were made at 87 different neutron energies. Fluctuations with magnitudes of about 1.5 % were observed in the cross section after all of the data had been correlated and corrected for the anisotropy and scattering effects that had been determined experimentally. A statistical treatment of the data yielded a compound nucleus level width of about 30 keV, which is reasonable for a ²⁸Al nucleus excited to 20–22 MeV. The observed structure can be explained in terms of Ericson fluctuation theory.
Energy levels of A = 21-44 nuclei (V)
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A study of 19Ne via 16O+τ reactions
1972, Nuclear Physics, Section A
Angular distributions and excitation functions have been measured for the ¹⁶O(τ,τ)¹⁶O and ¹⁶O(τ, α) ¹⁵O reactions from 3.2 to 7.0 MeV. Resonances have been observed in both channels. An optical-model-plus-resonance (OMPR) analysis of previously measured elastic data indicates a level with l = 1 around 3.65 MeV τ bombarding energy. A two-level analysis on the α-channel data indicates levels between 4.0 and 5.0 MeV with spins of $52$ and $72$ and like parities. An R-matrix analysis confirms this assignment and makes a strong case for a $32$ level in the same region. These levels together with previously discovered states in this excitation region of ¹⁹Ne are in good agreement with the predictions of the α-particle core-excited threshold state model (APCETS).
Statistical multistep compound emission in the Al27(He3,p)Si29 reaction
1980, Physical Review C
A study of the26Mg(3He, α)25Mg reaction in the incident energy range between 9 and 11 MeV
1973, Il Nuovo Cimento A Series 11

^†: Present address: Laboratorio de Fisica & Engenharia Nucleares, Sacavem, Portugal.

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Nuclear Physics A

Abstract

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Cited by (5)

Structure in the total <sup>27</sup>Al(n, α)<sup>24</sup>Na cross section around 14 MeV

Energy levels of A = 21-44 nuclei (V)

A study of <sup>19</sup>Ne via <sup>16</sup>O+τ reactions

Statistical multistep compound emission in the Al27(He3,p)Si29 reaction

A study of the<sup>26</sup>Mg(<sup>3</sup>He, α)<sup>25</sup>Mg reaction in the incident energy range between 9 and 11 MeV