Nuclear resonance fluorescence measurements by linearly polarized photon beam

Shizuma, Toshiyuki; Hayakawa, Takehito; Minato, Futoshi   ; Daito, Izuru*; Negm, H.*; Ogaki, Hideaki*; Miyamoto, Shuji*

Nuclear electric or magnetic dipole transitions can be studied by nuclear resonance fluorescence (NRF). The NRF process takes place via only the electromagnetic (EM) interaction. Since the EM interaction is well-known, the information on the nuclear dipole excitation can be obtained in a nuclear model-independent way. We used a quasi-monochromatic, linearly polarized photon beam produced by inverse Compton scattering of laser light with high energy electrons at the NewSUBARU electron storage ring facility of Hyogo University. A natural Cr target with a 1-cm diameter and a 3-cm length was irradiated by photon beams with the maximum energies of 8.2, 8.8, 9.4, 10, 11, and 12 MeV. Scattering photons were measured by three high purity Ge detectors with relative efficiencies of 100 to 140%. Two of the Ge detectors were horizontally or vertically placed at the scattering angle of 90. The polarization of the photon beams was fixed to the horizontal plane.