First measurement of polarisation transfer Cnx, in deuteron photodisintegration

A first measurement of the polarisation transfer from a circularly-polarised photon to the final state neutron (Cnx,) in deuterium photodisintegration has been carried out. This quantity is determined over the photon energy range 370 - 700 MeV and for neutron centre-of-mass breakup angles & SIM;45 - 120 degrees. The polarisation of the final state neutrons was determined by an ancillary large-acceptance nucleon polarimeter, surrounding a cryogenic liquid deuterium target within the Crystal Ball detector at MAMI. The polarimeter characterised (n, p) charge exchange of the ejected neutrons to determine their polarisation. The new Cnx, data are also compared to a theoretical model based on nucleonic and nucleon resonance degrees of freedom constrained by the current world-database of deuterium photodisintegration measurements. Structures in Cnx, observed in the region of the d*(2380) could not be explained by conventional models of deuteron photodisintegration. & COPY; 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.