Eur. Phys. J. A (2015) 51: 49
https://doi.org/10.1140/epja/i2015-15049-4

Special Article - Tools for Experiment and Theory

Analyzing power of AGATA triple clusters for gamma-ray linear polarization

¹ Dipartimento di Fisica, Università di Firenze, Firenze, Italy
² INFN, Sezione di Firenze, Firenze, Italy
³ INFN, Sezione di Padova, Padova, Italy
⁴ Dipartimento di Fisica, Università di Padova, Padova, Italy
⁵ INFN, Laboratori Nazionali di Legnaro, Padova, Italy
⁶ IFIC, CSIC, University of Valencia, Valencia, Spain

^* e-mail: bizzeti@fi.infn.it

Received: 15 November 2014
Accepted: 9 April 2015
Published online: 28 April 2015

Abstract

We have investigated the ability of AGATA triple clusters to measure the linear polarization of gamma rays, exploiting the azimuthal-angle dependence of the Compton scattering differential cross section. To this aim, partially polarized gamma rays have been produced by Coulomb excitation of the first excited state of ¹⁰⁴Pd and ¹⁰⁸Pd, which decay to the ground state by emission of gamma rays of 555.8 keV and 433.9 keV, respectively. Pulse-shape analysis and gamma-ray tracking techniques have been used to determine the position and time sequence of the interaction points inside the germanium crystals. Anisotropies in the detection efficiency have been taken into account using 661.6 keV gammas from a ¹³⁷Cs radioactive source. We obtain an average analyzing power of 0.451(34) at 433.9 keV and 0.484(24) at 555.8 keV.