Photodisintegration of the Deuteron at 18 MeV using Linearly Polarized Photons

Abstract

This thesis reports the: cross section, parameterized differential cross section, and analyzing power (a.k.a. the photon asymmetry), for neutron production via the photodisintegration of the unpolarized deuteron at 18 MeV using linearly polarized photons.

The data were collected in October 2010 using the High Intensity Gamma Source at the Duke Free-Electron Laser Laboratory located at Duke University in Durham, North Carolina. The ejectile neutrons from the photodisintegration reaction were measured using the Blowfish detector array: a spherical array of 88 BC-505 liquid organic scintillator cells which cover approximately pi steradians.

The initial goal of our experiment was to perform tests on the detector characteristics and check a few potential sources of systematic error, and so uncontaminated experimental runs were only taken with the remaining beam-time. Our data are therefore not optimized for precision, and so presented a number of data analysis challenges. This thesis delineates the challenges and respective solutions.

Contrary to earlier results near deuteron binding energy threshold, we see reasonable agreement with a theoretical calculation based on retarded one meson exchange with empirical cutoffs in the propagators, including: off-shell corrections, relativistic corrections and the Delta isobar degree-of-freedom. Our results show similar agreement to theory as previous experiments at 14 and 16 MeV, although we see no target length dependence: such has been observed at 20 MeV.