Measurement of theAyytensor analyzing power for theH

Abstract

Measurements of the unpolarized triple differential cross section and the A~t ensor analyzing power for the 'H(d, pp )n reaction were made using a 94.5 MeV polarized deuteron beam at the Indiana University Cyclotron Facility. Scattering angles i6 and P) and energy information were recorded for the two emerging protons using large-area wire chambers backed by stopping plastic scintillator detectors. Events were selected that were close to the symmetric constant relative energy geometry in order to enhance the sensitivity of the observables to off-shell and three-body effects. The measurements covered values of a, the center-of-mass angle between the incoming proton and the outgoing neutron, from 72 to 180'. Comparisons are made to Faddeev calculations that use either separable potentials or an exact treatment of the S-wave nucleon-nucleon interaction in conjunction with a perturbative treatment of higher partial waves. While none of these calculations, which use only two-nucleon interactions, is completely satisfactory, there remains too much variation among different theoretical treatments to demonstrate the need for including additional dynamical features in the three-body model.

Tensor analyzing powerAyyfordpbreakup in the symmetric constant relative energy configuration

“…1(a) and 1(b) the measured values of the tensor analyzing power AY~f rom Ref [6]. are compared to our theoretical predictions.…”

“…The final momenta of the outgoing nucleons are not integrated over the deuteron wave function, and in addition they can be chosen to some extent arbitrarily by concentrating on a specific kinematical configuration of the three outgoing nucleons. However, the existing database is still rather limited [5], especially in the case of spin observables, which can be both informative and stimulating [6,7].…”

“…In addition to Ref. [6] only one other measurement in the SCRE geometry was performed with polarized deuterons. However, this earlier measurement at Fd= 79.5 MeV [9] was of poor statistical precision and covered only a limited angular region.…”

“…The original theoretical analysis of the A data of Ref. [6] revealed sensitivities to both the energy and the nucleon-nucleon potentials used in the calculations. In addition, large variations among three different types of calculations were observed [6].…”

“…In the region of the maximum near n= 148, the loci and energy cuts required for extracting the SCRE analyzing powers are well defined (see Ref. [6]). Between +=120' and 140' the compact size of the locus in comparison with the experimental energy resolution may have permitted some contamination from non-SCRE data and shifted the Ayy tensor analyzing powers to more positive values in a systematic way [25].…”