Backward scattering of alpha particles by 16O at medium energies

doi:10.1016/0029-5582(65)90096-9

Nuclear Physics

Volume 74, Issue 2, December 1965, Pages 469-480

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Abstract

The backward elastic scattering of α-particles by ¹⁶O has been measured at incident α-particle energies of 41.9 and 49.7 MeV. The measurements at an incident energy of 49.7 MeV subtended the interval from 145° to 178° in the c.m. system, whereas the measurements at 41.9 MeV subtended the interval from 155° to 175°. The results are similar to those at lower energies, i.e. the phenomenon of a large peak at extremely backward scattering angles. Measurements at a fixed angle of 175° showed the differential cross section to be a smoothly decreasing function of increasing incident α-particle energy. An expression for a second-order correction to the measured differential cross section for the effects of finite geometry is given. The experimental angular distributions are compared with predictions based upon the exchange-scattering model introduced by Honda et al.

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Cited by (12)

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1975, Nuclear Physics, Section A
The elastic scattering of α-particles on ⁶Li nuclei has been measured from 20° to 170° (c.m.) and the inelastic scattering to the first excited state of ⁶Li has been measured for forward and backward angles. The elastic scattering angular distributions are calculated (i) in terms of pure potential scattering, (ii) in terms of potential scattering with an l-cut-off on the imaginary part of the potential and (iii) in terms of the coherent addition of the potential scattering amplitude and of the exchange amplitude. The third method gives the best fit to the data. The inelastic angular distributions are compatible with the macroscopic calculations, except in the very backward region where exchange phenomena are also shown to dominate.
Heavy-ion emission from light nuclei
1972, Nuclear Physics, Section A
Reactions involving the emission of heavy ions leading to low-lying states of the residual nucleus have been studied using 42 MeV α-particles incident on light target nuclei. The heavy ions resulting from these reactions were identified by mass number using the time-of-flight technique. With this method, products with a mass number as high as A = 14 could generally be separated from neighbouring isobars. Reactions leading to different particle masses from a particular target were studied simultaneously. Angular distributions and total cross sections were obtained for the reactions ¹²C(⁴He, ⁶Li)¹⁰B, ¹²C(⁴He, ⁷Be)⁹Be, ¹⁶O(⁴He, ⁶Li) ¹⁴N, ¹⁶O(⁴He, ⁷Li)¹³N, ¹⁶O(⁴He, ⁷Be)¹³C and ¹⁶O(⁴He, ⁹Be)¹¹C. A comparison of the experimental angular distributions and cross sections with statistical model calculations was carried out. We show that as the mass of the emitted heavy ion increases for a particular reaction, the fractional contribution of compound-nuclear processes increases. Considerable compound nuclear contributions to all the reactions studied are indicated. Comparison of the calculated and experimental results for the ¹⁶O(⁴He, ⁷Be) and ¹⁶O(⁴He, ⁷Li) reactions with those for the reaction ¹⁶O(⁴He, ⁸Be)¹²C indicate that there is no enhancement of the latter reaction due to α-clustering. Evidence is given for the conservation of isotopic spin in complex reactions proceeding through a short-lived compound nucleus. The possible astrophysical significance of low-energy α-particle-induced reactions in the nucleosynthesis of Li, Be and B is discussed.
Evidence for the existence of highly excited bands of intermediate resonances describing quasi-molecular rotations
1972, Physics Letters B
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1970, Nuclear Physics, Section A
Approximate scaling in the elastic peaks at backward
1989, Il Nuovo Cimento A
Optical model description of +O16 elastic scattering and alpha-cluster structure in Ne20
1983, Physical Review C

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Backward scattering of alpha particles by 16O at medium energies

Abstract

Nucl. Instr.

Nucl. Instr.

Phys. Rev.

Phys. Rev.

Phys. Rev.

Phys. Lett.

Backward scattering of alpha particles by ¹⁶O at medium energies