P.D. Miller

A measurement of parity non-conserving neutron spin rotation in lead and tin☆

Abstract The rotation, φ PNC , of a neutron beam polarization vector due to parity non-conserving forces is observed in natural Pb and Sn targets. The following values for φ PNC / l in units of 10 −6 rad/cm are found: Pb: +(2.24 ± 0.33), and Sn: −(3.19 ± 0.40). A positive sign corresponds to a right-handed rotation of the neutron spin about its momentum.

Elastic scattering of 3He particles by 9Be and 11B between 4.0 and 18.0 MeV

Abstract Angular distributions for the 3 He elastic scattering by 9 Be at 4, 6, 8, 10, 15 and 18 MeV and by 11 B at 8, 10, 12, 15 and 18 MeV have been measured. The elastic scattering data were analysed in terms of the optical model including spin-orbit coupling. Surface and volume absorption form factors for the central imaginary part have been examined with and without spin-orbit interaction. Good fits were obtained using either volume or surface absorption. Inclusion of the spin-orbit coupling is found to improve the fits, particularly at higher energies. Ambiguities in the optical-model potentials are found and discussed. The energy dependence of the parameters is investigated and general trends of the potential parameters are found. Average energy dependent potentials for 9 Be and 11 B have been deduced.

11B(3He, d)12C spectroscopic factors

Abstract Particle-identification techniques have been used to study the 11 B( 3 He, d) 12 C reaction. Angular distributions have been measured for incident 3 He energies of 10, 12 and 18 MeV for residual states in 12 C up to 16.11 MeV excitation. Elastic scattering of 3 He by 11 B has been measured at the same energies in order to extract optical-model parameters. The angular distributions have been analysed using DWBA calculations in order to obtain absolute spectroscopic factors. Zero-range DWBA was used with and without radial cut-off, and approximate finite-range DWBA calculations were also performed. Comparisons of the spectroscopic factors extracted using 11 B( 3 He, d) 12 C and 11 B(d, n) 12 C are given.

3He elastic scattering from 10B and 14C in the range 4 to 18 MeV

Abstract Differential cross sections for the 3 He elastic scattering from 10 B at 4, 8, 10,12, 15 and 18 MeV and from 14 C at 10, 12, 15 and 18 MeV have been measured. A systematic analysis of the elastic scattering data in terms of the optical model with surface absorption and including the spin-orbit interaction has been carried out. In most cases reasonably good agreement with the data is obtained. Inclusion of spin-orbit coupling generally improves the fits. Various ambiguities are found and examined. The results are compared with those obtained in the previous analysis 1,2) of 3 He scattering data from 11 B and 12 C. Isotope differences in the elastic scattering may be due to symmetry dependence of the 3 He optical potential. The variation of the opticalpotential parameters with energy and mass are investigated. General trends of various parameters are observed and some fluctuations are seen. Effects of experimental uncertainty on the potential parameters deduced are also examined. Average energy-dependent potentials consisting of eight parameters were obtained for each nucleus in the energy range studied.

A new measurement of the magnetic moment of the neutron

Abstract The magnetic moment of the neutron has been measured with a factor of one hundred improvement in accuracy. In terms of the Bohr magneton and proton magnetic moment, respectively, the result is μ n / μ B = −1.041 875 79 (26) × 10 −3 , μ n / μ p = −0.684 979 45 (17).

An investigation of the 9Be(3He, p)11B reaction at low energies

Abstract Angular distributions and excitation functions have been measured for proton groups leading to the 4.46, 5.03, 7.30, 7.99, 8.57 and 8.92 MeV excited states of 11B using 3He particles in the energy range 1–3 MeV. The experimental measurements are analysed in terms of a two-particle plane wave stripping formalism and a distorted wave Born approximation (DWBA). Results of both approaches are consistent with investigations which have been made on this reaction at higher energies. Parities assigned are as follows: 4.46 (−), 5.03 (−), 7.30 (+), 7.99 (+), 8.57 (−), 8.92 (−). Ranges of angular momenta include previous assignments.

The 14C(τ, α0)13C reaction at 6.0, 8.0 and 10.0 MeV

Abstract Angular distributions for 14 C(τ, α) 13 C leading to the ground state of 13 C were obtained at incident 3 He energies of 5.98, 8.0 and 10.0 MeV. 14 C(τ, τ) 14 C angular distributions were obtained at the same energies and used to obtain optical potentials for the entrance channel of (τ, α). Exit channel optical potentials were extracted from 13 C(α, α) 13 C angular distributions at 15.0, 18.0, 20.0 and 28.4 MeV. A DWBA analysis of the (τ, α) data was performed.

Absence of states in Be8 at 7.56, 13.91 and 18.00 MeV

The Li7 (p, α)α and Li7(p,{gamma})Be8 reactions have been studied in an effort to confirm recently reported states in Be8 at energies of 7.56, 13.91 and 18.00 MeV.

Multistep contributions to 11B(h, α)10B from 8.0 to 12.0 MeV

Abstract Various improvements to the usual distorted-wave Born approximation description of direct reactions on light nuclei are investigated, using 11 B(h, α) 10 B as an example, and including finite-range effects, compound nuclear contributions, and deformation as well as inelastic process in the entrance and exit channels. It is found that only the inelastic processes and deformation play an important role, and that their inclusion, via the coupled-channel Born approximation, very satisfactorily describes the available data in shape and magnitude.

A study of the 11B(3He, p)13C reaction at 12, 10, 8, 6 and 4 MeV

Abstract Angular distributions for eight proton groups corresponding to states in 13 C have been measured at incident 3 He energies of 4, 6, 8, 10 and 12 MeV. These states are p 0 (ground state), P 1 (3.09), p 1 (3.68), p 3 (3.85), p 4 (6.86), p 7 (7.68), pio(9.50) and p 11 (9.90). The angular distributions have been fitted with DWBA analyses using a zero-range approximation. No radial cut-offs were used. In general the data are reasonably well fit at incident energies of 10 and 12 MeV.