A. Chisholm

Polarization in neutron-proton scattering at 16.2 MeV

Abstract The polarization in the scattering of neutrons from protons has been measured at a lab neutron energy of 16.2 MeV for the three c.m. angles 70°, 100° and 130°, at which the measured polarizations were (+2.95 ± 0.86) %, (+1.84 ± 0.91)% and (+1.62 ± 0.99) % respectively.

Polarization in the elastic scattering of 2–3 MeV neutrons by deuterons

Abstract Large polarization effects have been ovserved in the elastic scattering of polarized neutrons from the D-D reaction by deuterons. The polarization for 90° centre of mass scattering is 0.58±0.05 at 2.26 MeV and 0.86±0.19 at 3.1 MeV and was measured by studying the asymmetry in the distribution of recoil deutrons in deuterium filled proportional counters.

Analysing power for neutron-proton scattering at 14.1 MeV

Abstract The analysing power A γ ( θ ) for neutron-proton scattering has been measured at 14.1 MeV for c.m. angles between 50° and 157°. A polarized neutron beam was produced by the reaction 3 H ( d , n ) 4 He at 110 keV, using polarized deuterons from an atomic beam polarized ion source. Liquid and plastic scintillators were used for proton targets and the scattered particles were detected in an array of plastic scintillators. Use of the associated alpha technique, multi-parameter recording of events and off-line computer treatment led to very low backgrounds. The results differ significantly from the predictions of the phase-shift analyses of Yale IV, Livermore X and Arndt et al . We find, however, excellent agreement with the predictions of the “Paris potential” of Lacombe et al . Existing n-p analysing power results up to 30 MeV are surveyed and found to be consistent. An attempt was made to look for an isospin splitting of the triplet P-wave phase shifts.

A 14 MeV polarized neutron facility

Abstract A facility for performing scattering experiments with 14 MeV polarized neutrons is described. The polarization is produced in an atomic beam source. The neutron polarization is found to a relative accuracy of 3 %. Backgrounds are very low.

Study of multiple scattering effects in neutron-proton analysing power measurements

Abstract A neutron-proton analysing power experiment at 14 MeV has been simulated, using the Monte Carlo method, with the aim of investigating the effects of multiple scattering in the scatterer on the measured analysing power. Results of the simulation are compared with some experimental data. We find that multiple-scattering effects are not the limiting factor on the accuracy of such experiments.

The analysing power in the elastic scattering of 14 MeV neutrons by deuterons

Abstract The analysing power for the elastic scattering of 14.1 MeV neutrons by deuterons has been measured at 17 angles between 44.5° and 161.6° in the centre of mass. A polynomial fit to this data combined with that at the same energy by Preiswerk et al. and Fischer et al. has been made and compared with a similar fit to the p-d data of Duder et al. Significant differences are found over the full angular range. Similar comparisons have also been made on existing data at other energies between 8 and 50 MeV. The polynomial expansion coefficients have been determined as a function of energy and show differences between p-d and n-d scattering which vary smoothly with energy and appear to be greater than the experimental errors.

Computer Simulation of Multiple Scattering Effects in 14 MeV n-p Analyzing Power Measurements

We are presently measuring the analyzing power of 14 MeV neutrons elastically scattered by protons in the liquid scintillator NE213. Our detection method is to observe the pulse height spectrum of recoil nuclei in the scintillator when gated by neutrons scattered into left and right side detectors. While other sources of background may be removed in a well planned experiment, multiply scattered neutrons are not eliminated by the gating, and the detailed shape of the multiply scattered background under the n-p single-scattering peak remains difficult to determine experimentally. Moreover, this background may be different when gated by left or right side detectors since n-C elastic scattering may occur with large analyzing powers. There is thus the possibility of a systematic error in determining the n-p analyzing power. Leemann et all) have measured significantly different 14.2 MeV n-p analyzing powers at θcm = 90° with scatterers of diameter 3.81 cm and 2 cm, and propose that multiple scattering events involving carbon may be the cause of this discrepancy. Yet Jones and Brooks2), with a 1.5 cm3 scatterer at 21.6 MeV obtained an n-p analyzing power consistent with the larger of Leemann’s scatterers.

Analyzing Power of 14 Mev Neutrons on Light Nuclei

We are at present measuring the analyzing powers for the scattering of 14 MeV polarized neutrons for the following nuclei: (a) protons (b) deuterons (c) carbon (ground state and 4.4 MeV level)

Proton Polarization in the % MathType!MTEF!2!1!+-% feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaWraaSqabe% aacaaIZaaaaGqaaOGaa8hsaiaa-vgacaWFOaGaa8hzaiaa-XcaceWF% WbGbaSaacaWFPaWaaWraaSqabeaacaaI0aaaaOGaa8hsaiaa-vgaaa% a!3F2E! Reaction

For incident deuterons of energy less than about 1.5 MeV the \({}^3He(d,\vec p){}^4He\) reaction is amenable to a fairly simple phenomenological analysis1). To date measurements of the differential cross section2), measurements-with the deuteron beam polarized3), with the 3He target polarized4) and (at one energy) with two polarizations simultaneously measured5) bring us close to having a complete set of data on this reaction.