Author :
Kishimoto, Y. ; Gunji, S. ; Ishigaki, Y. ; Kanno, M. ; Murayama, H. ; Ito, C. ; Tokanai, F. ; Suzuki, K. ; Sakurai, H. ; Mihara, T. ; Kohama, M. ; Suzuki, M. ; Hayato, A. ; Hayashida, K. ; Anabuki, N. ; Morimoto, M. ; Tsunemi, H. ; Saito, Y. ; Yamagami, T
Abstract :
We have been developing an instrument named "PHENEX (Polarimetry for High ENErgy X rays)" to measure polarization in the hard X-ray region. The PHENEX polarimeter consists of detector modules called "unit counters". We have investigated the performance of the unit counter, using a highly polarized beam in KEK-PF BL14A. From these measurements, we obtained a detection efficiency of 20% and a modulation factor (analyzing power for polarization) of 53% for 80 keV X rays. Assembling four unit counters, a balloon-flight version was constructed and a preliminary observation of the Crab Nebula was carried out on Jun. 13th, 2006. During this flight, the PHENEX polarimeter observed the Crab for about one hour and detected its hard X rays with a significance of 9sigma. From this result, we expect that a PHENEX polarimeter with nine "unit counters" would achieve a 17% minimum detectable polarization of the Crab Nebula with 3sigma significance in a 3-hour observation.
Keywords :
X-ray astronomy; astronomical polarimetry; polarimeters; Crab Nebula; PHENEX; balloon-flight version; detection; hard X-ray polarization; high energy X rays; modulation factor; polarimeter; polarimetry for high energy instrument; unit countee; we factor; Energy measurement; Extraterrestrial measurements; Indium tin oxide; Instruments; Plastics; Polarimetry; Polarization; Power measurement; Radiation detectors; Synchrotron radiation; Astrophysics; Crab Nebula; PHENEX; hard X ray; polarimeter;
