High energy and high brightness laser compton backscattering gamma-ray source at IHEP

Based on the LINAC of BEPCII, a high-polarized, high bightness, energy-tunable, monoenergetic laser compton backscattering (LCS)gamma-ray source is under construction at IHEP. The gamma-ray energy range is from 1 MeV to 111 MeV. It is a powerful and hopeful researchplatform to reveal the underlying physics of the nuclear, the basic particles and the vacuum or to check the exist basic physical models, quantumelectrodynamic (QED) theories. In the platform, a 1.064 mm Nd:YAG laser system and a 10.6 mm CO_(2) laser system are employed. All the triggersignals to the laser system and the electron control system are from the only reference clock at the very beginning of the LINAC to make sure thetemporal synchronization. Two optical transition radiation (OTR) targets and two charged-couple devices (CCD) are used to monitor and to alignthe electron beam and the laser beam. With the LCS gamma-ray source, it is proposed to experimentally check the gamma-ray calibrations, thephoton-nuclear physics, nuclear astrophysics and some basic QED phenomena.

Theoretical study of magnetic lens with parallel beam matched

The magnetic lens(Zumbro lens) is a critical part in proton radiography. Traditionally the matched beam for Zumbro lens in proton radiography is a virtual point source beam, which is not suitable for some cases, such as cylindrical samples. In these cases, a parallel beam is more appropriate. In this paper, a method, which uses quadrupole beamline, is proposed for designing a magnetic lens with parallel beam matched. Theoretical analysis is given. The results show that the matched beam for this lens is indeed parallel beam, while the major merits of Zumbro lens are inherited. Following this method, a theoretical design based on the 11-Me V cyclotron is presented.

Hard x-ray transmission curved crystal spectrometers(10–100 keV) for laser fusion experiments at the ShenGuang-Ⅲ laser facility

Two transmission curved crystal spectrometers are designed to measure the hard x-ray emission in the laser fusion experiment of Compton radiography of implosion target on ShenGuang-III laser facility in China. Cylindrically curvedα-quartz(10–11) crystals with curvature radii of 150 and 300 mm are used to cover spectral ranges of 10–56 and17–100 ke V, respectively. The distance between the crystal and the x-ray source can be changed over a broad distance from 200 to 1500 mm. The optical design, including the integral reflectivity of the curved crystal, the sensitivity, and the spectral resolution of the spectrometers, is discussed. We also provide mechanic design details and experimental results using a Mo anode x-ray source. High-quality spectra were obtained. We confirmed that the spectral resolution can be improved by increasing the working distance, which is the distance between the recording medium and the Rowland circle.