Polarimetry of short-pulse gamma rays produced through inverse Compton scattering of circularly polarized laser beams.
We have developed a polarimetry of ultrashort pulse gamma rays based on the fact that gamma rays penetrating in the forward direction through a magnetized iron carry information on the helicity of the original gamma rays. Polarized, short-pulse gamma rays of (1.1+/-0.2)x10(6)/bunch with a time duration of 31 ps and a maximum energy of 55.9 MeV were produced via Compton scattering of a circularly polarized laser beam of 532 nm off an electron beam of 1.28 GeV. The first demonstration of asymmetry measurements of short-pulse gamma rays was conducted using longitudinally magnetized iron of 15 cm length. It is found that the gamma-ray intensity is in good agreement with the simulated value of 1.0x10(6). Varying the degree of laser polarization, the asymmetry for 100% laser polarization was derived to be (1.29+/-0.12)%, which is also consistent with the expected value of 1.3%.
Fukuda
M
M
Department of Physics, Tokyo Metropolitan University, Minami-Osawa, Hachioji-shi Tokyo 192-0397, Japan.
Aoki
T
T
Dobashi
K
K
Hirose
T
T
Iimura
T
T
Kurihara
Y
Y
Okugi
T
T
Omori
T
T
Sakai
I
I
Urakawa
J
J
Washio
M
M