Eur. Phys. J. A (2009) 39: 267-280
https://doi.org/10.1140/epja/i2008-10719-x

Regular Article - Experimental Physics

Measurements of the ratio R_dp of the quasi-elastic nd p(nn) to the elastic np pn charge-exchange process yields at zero proton emission angle over the 0.55-2.0 GeV neutron beam energy region

¹ Joint Institute for Nuclear Research, Veksler and Baldin Laboratory of High Energies, Dubna, Russia
² Kurchatov Institute, Russian Scientific Center, Moscow, Russia
³ Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics, Dubna, Russia
⁴ Joint Institute for Nuclear Research, Dzhelepov Laboratory of Nuclear Problems, Dubna, Russia
⁵ Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic
⁶ Joint Institute for Nuclear Research, Laboratory of Particle Physics, Dubna, Russia
⁷ Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia, Bulgaria
⁸ St. Petersburg Nuclear Physics Institute, Gatchina, Russia

Received: 28 April 2008
Revised: 20 November 2008
Accepted: 7 January 2009
Published online: 11 February 2009

Abstract

New experimental results on the ratio R_dp of the quasi-elastic charge-exchange yield at the outgoing proton angle = 0^° for the nd p(nn) reaction to the elastic np pn charge-exchange yield are presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8 and 2.0GeV. The intense neutron beam with small momentum spread was produced by break-up of deuterons which were accelerated and extracted to the experimental hall. In both reactions mentioned above the outgoing protons with the momenta p _p approximately equal to the neutron beam momentum p _{n, beam} were detected in the directions close to the direction of incident neutrons, i.e. in the vicinity of the scattering angle = 0^° . Measured in the same data taking runs, the angular distributions of the charge-exchange reaction products were corrected for the well-known instrumental effects and averaged in the vicinity of the incident neutron beam direction. These corrected angular distributions for every of nd p(nn) and np pn charge-exchange processes were proportional to the differential cross-sections of the corresponding reactions. The data were accumulated by the Delta-Sigma set-up magnetic spectrometer with two sets of multiwire proportional chambers located upstream and downstream of the momentum analyzing magnet. Inelastic processes were considerably reduced by the additional detectors surrounding the hydrogen and deuterium targets. The time-of-flight system was applied to identify the detected particles. The new R_dp data are compared with the existing ones, which were obtained below 1GeV, and with the calculations which were made using the phenomenological NN amplitude sets.