Precision X-Band Linac Technologies for Nuclear Photonics Gamma-Ray Sources

Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabled by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw)

Effects of Gamma and Electron Beam Irradiation on FBG and DFB-FL

Abstract This paper reports the comparative experimental study concerning the irradiation effects of gamma-ray and electron beam on fiber Bragg grating (FBG) and distributed feedback fiber laser (DFB-FL). The obvious reflection wavelength shifts are observed for FBGs and DFB-FLs without evident changes in reflectivity and bandwidth under the current experimental irradiation condition, up to 60 kGy gamma radiation and 100 kGy electron beam radiation, respectively. Especially for DFB-FLs, evident attenuation in output power is observed and the rising tendency of the attenuation under increasing irradiation dose is demonstrated as well. Thus, the DFB-FLs are more suitable for radiation detection as compared to passive FBGs.</jats:p

Technical solutions for the control and command system of a Plasma Focus device

The paper presents the technical problems related to the electrical control and command system (ECC system) for the plasma focus installation IPF-4/5A having the following main parameters: 1 MA plasma current and 40 kJ energy stored at 20 kV charging voltage. The ECC system applies 23 interlocked logical commands, acquires and processes 28 logical states, acquires, processes and displays continuously the main slow-varying signals coming from IPF-4/5A subassemblies. All the plasma focus installation operational sequences are governed by strict hard and soft interlocking using in parallel two control and command systems: one based on PC-control methods and another based on classical control techniques