High Energy Photon Production with Laser-Compton Backscattering and Photo Nuclear Reaction

利用激光束对能量为1GeV的相对论电子束的康普顿背散射，在新SUBARU储存环上产生了光子束。(l)利用六块反射镜和一个透镜将波长为1064 nm的激光光子注入到相互作用区。（2）通过最大化探测器的计数率来实现激光束轴和准直器对准的微调。（3）用HPGe探测器测量了背散射光子的能谱。最大光子能量为17.6MeV。我们使用了20 mm φ、10 mm φ和2 mm φ三种准直器。(4)所得到的能谱进行了比较与模拟模型计算使用EGS 4-代码。通过假设每个碰撞点处的理想能谱，并考虑探测器的几何尺寸和各种介质（如反射镜和玻璃窗等）的衰减，计算出的模拟能谱与测量的能谱吻合得很好。(5)比较结果表明，在20 mm φ、10 mm φ和2 mm φ准直器上，探测到的光子数分别为4 × 10^3/sec/mA/W、2 × 10^3/sec/mA/W和3 × 10^2/sec/mA/W。(6)用吸收法测量了El巨共振能区的核光吸收截面（n，γ）。利用背散射光子测量了197 Au的吸收系数。我们获得了530毫巴的峰值截面。在此之后，我们将不仅测量巨共振，而且还使用背散射光子测量离散态。

We have generated photon beam using the Compton backscattering of laser beam on the relativistic electron beam of 1 GeV energy in the storage ring, NewSUBARU. (l) The laser photons of the wave length of 1064nm were injected to the interaction area by using six mirrors and a lens. (2)The fine -tuning of the laser-beam axis and the collimator alignment was accomplished by maximizing the count rate in a detector. (3)The energy spectra of the backscattering photons have been measured with HPGe detector. The maximum photon energy is 17.6 MeV. We have used three kinds of collimators that are 20mmφ, 10mmφand 2mmφ. (4) The obtained energy spectra were compared with the simulated model calculations using the EGS4-code. The simulated energy spectra calculated by assuming an ideal energy spectra at each collision point and by taking account of the geometry including the detector size and of the attenuation by various media such mirror and glass window etc. The calculations show good agreements with the measured energy spectra. (5) From the comparisons, the detected photons are about 4 x 10^3/sec/mA/W, 2 x 10^3/sec/mA/W and 3 x 10^2/sec/mA/W for 20mmφ, 10mmφand 2mmφ collimators, respectively. (6) The measurement of the nuclear photo-absorption cross sections (n, γ ) in the El giant resonance energy region has been carried out using the absorption method. The absorption coefficient for 197Au has been measured using the backscattering photons. We have obtained the peak cross section of 530 mb. Hereafter, we will measure not only the giant resonance but also discrete states using the backscattering photons.