Neutron–proton analyzing power at 12 MeV and inconsistencies in parametrizations of nucleon–nucleon data

Abstract

We present the most accurate and complete data set for the analyzing power Ay(θ) in neutronproton scattering. The experimental data were corrected for the effects of multiple scattering, both in the center detector and in the neutron detectors. The final data at En = 12.0 MeV deviate considerably from the predictions of nucleon-nucleon phase-shift analyses and potential models. The impact of the new data on the value of the charged pion-nucleon coupling constant is discussed in a model study.

Corrections for the polarization-dependent efficiency and new neutron-proton analyzing power data at 7.6 MeV

“…This is in agreement with the model study of Ref. [5], which suggested a charge dependence of the pion-nucleon coupling constant.…”

“…1(a) and listed in Table I, are based on the same experimental procedure as Ref. [5]. All four of these data sets show small systematic improvements in their overall smoothness, which offer further confirmation that our new 12 C library is an improvement over those used in Refs.…”

“…The circles in (a) are the same data that appear in Ref. [5]. The solid curves are the PSA predictions of Ref.…”

Analyzing PowerAy(θ)ofn→−HeEsterline1, Tornow2, Deltuva3 et al. 2013Phys. Rev. Lett.Self Cite9070View full textAdd to dashboardCite

“…Details about the neutron detectors and the polarimeter are given in Ref. [13]. In order to minimize instrumental asymmetries inherent to theñ-3 He andñ-4 He scattering assemblies, the neutron polarization direction was switched betweenŷ and Àŷ at a frequency alternating between 10 and 5 Hz by flipping the associated proton or deuteron polarization at the atomic beam polarized ion source.…”

“…[13]. In brief, separate triggers for theñ-3 He andñ-4 He setups were formed from a coincidence between the active scatterer ( 3 He or 4 He gas scintillator) and, collectively, their associated neutron detectors.…”