Polarization of the neutrons from the Be9(α, n0)C12 and Be9(α, n1)C12∗ reactions

doi:10.1016/0029-5582(65)90122-7

Nuclear Physics

Volume 67, Issue 1, May 1965, Pages 193-202

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Abstract

The polarizations of the neutrons from the Be⁹(α, n)C¹² reaction leading to the ground and first excited states of C¹² were measured as a function of neutron emission angle for several bombarding energies between 1.90 and 4.50 MeV. polarization of the neutrons was measured by scattering from a He⁴ analyser in the form of a high pressure gas scintillator. Asymmetries in the scattering of the neutrons from the helium were measured with the aid of an electro-magnet which could rotate the polarization vector of the neutrons between the source and the scatterer. Values of the polarization as large as 40% were observed for the ground-state neutrons, while the maximum polarization of the excited-state neutrons was about 25%. In general, the polarizations vary appreciably with energy and angle.

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Cited by (12)

Nuclear data sheets for A = 1
2005, Nuclear Data Sheets
Polarization measurement of fast neutrons from the 9Be(α, n)12C and the 13C(α, n)16O reaction using a high-pressure 4He-polarimeter in a new design
1990, Nuclear Inst. and Methods in Physics Research, A
The angular distribution of the polarization of neutrons produced in (α, n) reactions has been measured using a high-pressure ⁴He-polarimeter in a new design. The thin-walled (1 mm) scintillator cell has been constructed for gas pressures of up to 180 bar. For the ⁹Be(α, n)¹²C reaction, polarization degrees between −0.15 to +0.62 in the α-energy range of 1.9–3.1 MeV were obtained. In the case of ¹³C(α, n)¹⁶O, the neutron polarization has been determined at E_α = 2.406 and 3.308 MeV. For reaction angles between 0–70°, the polarization lies between −0.4 and +0.2.
A liquid-helium neutron polarimeter with a simple structure and in stable operation
1975, Nuclear Instruments and Methods
A neutron polarimeter was constructed for a study of the depolarization of polarized neutrons in neutron-nucleus elastic scattering at E_n = 1.36 MeV. The polarimeter consists of a liquid-helium scintillation counter, a spin-precession solenoid, a time-of-flight neutron spectrometer, and a neutron-gamma pulse-shape discriminator. The degrees of neutron polarization in ⁹Be(αn₀)¹²C_g.s. and ¹²C(d,n₀)¹³Ng.s. reactions were measured as a performance test of the polarimeter. In the time-of-flight spectrum for scattered neutrons with energies as low as 1.36 MeV, the signal-to-background ratio was attained to a factor of 20 or more.
Neutron polarization from the reaction 9Be(α, n)12C
1974, Nuclear Instruments and Methods
The nuclear spin-spin effect in 59Co
1972, Nuclear Physics, Section A
Measurements of the spin-spin effect σ_ss in the neutron total cross section of ⁵⁹Co covering the energy range from 0.3 to 8.0 MeV are reported. The measurements were made with a target having a nuclear polarization of 33 %. Fine structure in the spin-spin effect can be explained by the statistical theory of Carlson and Barschall. The evidence for intermediate structure is inconclusive. The gross energy dependence of σ_ss is not well reproduced by optical-model calculations employing a macroscopic spin-spin potential, even when a tensor term is added to the usual spherical potential. There is thus considerable ambiguity in the potential parameters extracted from the data. The experimental values of σ_ss are also much larger than the predictions of any reasonable microscopic model, particularly at neutron energies less than 1 MeV.
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1970, Nuclear Physics, Section A

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^†: This article is partially based on a thesis submitted to the Graduate School of the University of Notre Dame by G. P. Lietz in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

^††: Present Address: U.S. Army Materials Research Agency, Watertown Arsenal, Watertown, Massachussets. This article is partially based on a thesis submitted to the Graduate School of the University of Notre Dame by S. F. Trevino in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

^†††: Alfred P. Sloan Research Fellow, September 1962-September 1964

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Nuclear Physics

Abstract

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Cited by (12)

Nuclear data sheets for A = 1

Polarization measurement of fast neutrons from the <sup>9</sup>Be(α, n)<sup>12</sup>C and the <sup>13</sup>C(α, n)<sup>16</sup>O reaction using a high-pressure <sup>4</sup>He-polarimeter in a new design

A liquid-helium neutron polarimeter with a simple structure and in stable operation

Neutron polarization from the reaction <sup>9</sup>Be(α, n)<sup>12</sup>C

The nuclear spin-spin effect in <sup>59</sup>Co

Energy levels of light nuclei A = 13-15