The laser Compton scattering gamma ray beamline at the synchrotron light facility NewSUBARU supplies a quasi-monochromatic, polarized, high-energy photon beam. A gamma ray flux of more than 107 ...photons/s is generated at a photon energy range of 1 - 73 MeV. Emission distributions of the fast neutrons generated from different target materials were measured as a function of the polarization angle of the linear polarized gamma-ray beam using a time-of-flight method with fast plastic scintillators. The neutron distributions were consistent with a previous theoretical result. The relatively slow neutrons were measured via an activation method. The result demonstrated the small anisotropy of the slow neutron emission.
A time projection chamber (TPC) can be used to measure the polarization of gamma rays with excellent angular precision and sensitivity in the MeV-GeV energy range through the conversion of photons to ...e+e− pairs. The Hermetic ARgon POlarimeter (HARPO) prototype was built to demonstrate this concept. It was recently tested in the polarized photon beam at the NewSUBARU facility in Japan. We present this data-taking run, which demonstrated the excellent performance of the HARPO TPC.
Spectra of neutrons produced by a photonuclear reaction from a 197Au target were measured using 16.95 MeV linearly and circularly polarized photon beams at NewSUBARU-BL01 using a time-of-flight ...method. The difference in the neutron spectra between the cases of a linearly and circularly polarized photon was measured. The difference in the neutron yield increased with the neutron energy and was approximately threefold at the maximum neutron energy. In a direction perpendicular to that of the linear polarization, the neutron yields decreased as the neutron energy increased.
Photo-neutron energy spectra for Eg=23.1 and 26.6 MeV mono-energetic photons on natC were measured using laser Compton scattering facility at NewSUBARU BL01. The photon energy spectra were evaluated ...through measurements and simulations with collimator sizes and arrangements for the laser electron photon. The neutron energy spectra for the natC(g,xn) reaction were measured at 60 degrees in horizontal and 90 degrees in horizontal and vertical with respect to incident photon. The spectra show almost isotropic angular distribution and flat energy distribution from detection threshold to upper limit defined by reaction Q-value.
The neutron-emission spectrum from a 197Au target excited with a 16.6 ±0.2 MeV, monoenergetic, linearly polarized photon beam was measured using the time-of-flight method at the NewSUBARU-BL01. Two ...components were clearly detected in the neutron spectrum produced by photonuclear reactions. One component component (A) shows an evaporation-like spectrum with energies up to 4 MeV. The spectrum of the other component component (B) is shaped like a bump and energies ≥4 MeV. The intensity of the component (A) does not show any definite angular dependence, whereas, that of the component (B) follows the relation a+ b cos(2Θ) as a function of the angle Θ between the polarization and detector directions.
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