GRETINA as a Compton Polarimeter*

The ability to measure both the spin and parity of an excited state in an oriented nucleus through its emitted gamma radiation can provide information on the multipolarity, mixing ratio, and parity of the transition. GRETINA has been characterized as a Compton-polarimeter with interaction positions from tracking by examining gamma-rays emitted in the 24Mg(p,p') reaction at 2.45 and 6 MeV[1]. In this work, we consider GRETINA as a traditional Compton-polarimeter, where the intensity of the scattered radiation measured between physical detecting elements (segment and crystal boundaries) is used to determine its polarization sensitivity. The 36-fold crystals of GRETINA along with the arrays compact geometry allows many elements to act as both scatterer and detector across the array. This provides a direct comparison of the arrays ability to measure the linear polarization to measurements made over the past decades. The performance of GRETINA as a traditional Compton-polarimeter will be presented.

[1] A. Wiens et al: BAPS2014.HAW.DK.2, to be published.