I. Slaus

Toward a resolution of the neutron-neutron scattering-length issue

Abstract We report a high-precision determination of the 1 S 0 neutron–neutron scattering length ( a nn ) using the 2 H( π − , nγ ) n reaction. The value obtained in the present work is −18.50± 0.05 (statistical) ± 0.44 (systematic) ± 0.30 (theoretical) fm, which is consistent with the values from previous measurements. Combining our result with previous measurements reduces the total uncertainty in the world average of a nn to ±0.4 fm, matching the accuracy to which the charge-symmetric parameter a pp is determined.

Verification of the space-star anomaly in nd breakup

Abstract Cross-section measurements of a collinear configuration, the space-star and the coplanar-star configurations in nd breakup at E n = 13.0 MeV are reported. The present measurements for the collinear configuration are in good agreement with pd and nd data. Our coplanar-star data are consistent with theoretical predictions and resolve the reported problem with this configuration. The previously observed large discrepancy between theory and nd cross-section data for the space-star configuration is confirmed in the present work.

The low-energy neutron-deuteron analyzing power and the 3P0,1,2 interactions of nucleon-nucleon potentials

Data for the analyzing power Ay(θ) for the elastic scattering of neutrons from deuterons have been measured at 5.0, 6.5 and 8.5 MeV to an accuracy of ±0.0035. Surprisingly large differences have been observed at these low energies between the data and rigorous Faddeev calculations using the Paris and Bonn B nucleon-nucleon potentials. The Ay(θ) data provide a stringent test for our present understanding of the on-shell and off-shell 3P0,1,2 nucleon-nucleon interactions.

The study of the reaction D(p, 2p)n at 46 MeV☆

Abstract Correlation spectra from the p + d breakup reaction have been measured at 46 MeV. The data, which show pronounced effects due to final state interactions and quasi-free processes, have analyzed in terms of three different spectator model calculations and the Chew-Low extrapolation procedure.

Study of the Reaction C-12(n,3-alpha)n From Threshold To en = 35 Mev

Kinematically complete measurement of the reaction 12C(n,3 α)n has been performed using nuclear emulsions exposed to neutrons of continuous energy. Alpha particle energy spectra and cross sections for the reaction (n,3 α) as well as for specific channels 12C(n, 8Begs)nα. and 12C(n,12C9.63)n have been measured up to 35 MeV incident energy with an accuracy of about 20%.

The reactions 10B(n, t)αα, 7Li(n, t)αn and 6Li(n, d)αn at 14.4 MeV

Abstract The reactions 10 B(n, t)αα, 7 Li(n, t)αn and 6 Li(n, d)αn have been studied at 14.4 MeV. The energy spectra indicate the importance of the sequential decay mechanism in these processes. The Phillips-Griffy-Biedenharn model gives a good fit to the data. No evidence of spatial localization has been observed.

Finite-range DWBA analysis of (p, α) reactions on 9Be and 11B

Abstract The ground state angular distributions of the reactions 9 Be(p, α) 6 Li and 11 B(p, α) 8 Be are analyzed by means of the DWBA theory. One-step direct mechanisms only are considered, but for both reactions the inclusion of the heavy-particle pick-up is found to be essential. DWBA fits to the data are obtained (a) in the zero-range approximation, (b) in the “fixed-range” approximation and (c) by an exact finite-range calculation. Only the latter method yields both an acceptable fit and reasonable values for the spectroscopic factors.

Inelastic scattering of 46 MeV protons from 12C

Abstract The differential cross sections for the excitation of nine levels of carbon have been measured each at 35 angles from 15° to 150°. The cross sections for the 4.4 and 9.6 MeV levels have a typical relative accuracy of 3%, while the measurements for the 7.7, 10.8, 11.8, 12.7, 14.1, 15.1 and 16.1 MeV levels have a typical accuracy of 10%. The cross sections decrease by from one to three orders of magnitude through the measured angular range. Levels at 13.3 and 16.6 MeV were not observed. The angular distributions have been compared with distorted wave calculations using both macroscopic and microscopic approaches.

The D(p, 2p)n reaction at 14.45 MeV and the Amado model

Abstract Data have been obtained for the reaction D(p, 2p)n at E p = 14.45 MeV at θ 3 = θ 4 = 25°, 30°, 35° and 43°. The results are compared with calculations using the Amado model, the ordinary truncated multiple-scattering series and a modified truncated series, which includes the p-d initial state interaction.

The reaction d(p, pp)n measured with bol at Ep = 50 MeV

Abstract We measured proton-deuteron breakup with the multi-detector system BOL for protons with an energy of 50 MeV hitting a deuterated polyethylene target. Proton-proton coincidences were registered with 40 position-sensitive detector telescopes. We present data covering ~ 85 % of the four-dimensional kinematical phase space. The data are compared with Faddeev calculations using two local S-wave Malfliet-Tjon potentials. Regions of discrepancy between data and theory in two-dimensional (2D) subspaces (cuts) are shown to be connected in 4D. The cross section structure (experimental and theoretical) is studied in a 4D representation consisting of a 2D matrix of 2D matrices. Prominent patterns are observed in the 4D differential cross section which can be traced back to quasi-two-body reaction mechanisms. Observed symmetries can be understood in terms of the simple impulse approximation.