Cavity optimization for compact accelerator-based free-electron maser
In previous works [1] we have successfully commissioned pre-bunched beam pumped free electron maser based on Stimulated Coherent Diffraction Radiation (SCDR) generated in an open resonator. An ultra-fast Schottky Barrier Diode (SBD) detector has enabled us to investigate the properties of the radiation in the range from 3 to 5 mm of wavelengths among broad frequencies stored in the cavity as well as the intrinsic properties of the cavity itself. We observed a turn-by-turn SCDR generated by a multibunch electron beam and directly measured the opened cavity quality factor of 11.4. In this report we represent the work directly related to optimization of both the maser system to achieve higher quality factor of the cavity essential to gain soft X-ray production via Thomson scattering in the next stage of the experiment and measurement system for better characterization of the maser light. One way of optimization is to minimize losses of energy due to transmission through resonator mirrors. For this purpose we have designed and constructed a test setup to investigate reflection and transmission properties of different mirror materials. Theoretical calculations have been performed using optical constants and theoretical models of electrical permittivity to compare with experimental results. In this report we summarize the experimental activity, represent new experimental results and represent steps undertaken to achieve the new resonator mirror design. For better understanding of the resonator performance a test of the SBD detector linearity is also demonstrated.
Diffraction Radiation from Relativistic Particles
Foreword Preface 1. Radiation from Relativistic Particles 2. General Properties of Diffraction Radiation 3. Diffraction Radiation at Optical and Lower Frequencies 4. Diffraction Radiation in the Ultraviolet and Soft X-Ray Regions 5. Diffraction Radiation at the Resonant Frequency 6. Diffraction Radiation from Media with Periodic Surfaces 7. Coherent Radiation Generated by Bunches of Charged Particles 8. Diffraction Radiation in the Pre-Wave (FRESNEL) Zone 9. Experimental Investigations of Diffraction Radiation Generated by Relativistic Electrons References
Electron dose-rate conversion factors for external exposure of the skin from uniformly deposited activity on the body surface.
Dose-rate conversion factors have been calculated for external exposure of the skin from electrons emitted by sources that are deposited uniformly on the body surface. The dose-rate factors are obtained from electron scaled point kernels developed by Berger (Be71; Be73; Be74). The dose-rate factors are calculated at depths of 4, 8, and 40 mg cm-2 below the body surface as recommended by Whitton (Wh73), and at a depth of 7 mg cm-2 as recommended in ICRP Publication 26 (ICRP77). The dependence of the dose-rate factors at selected depths on the energy of the emitted electrons is displayed. The dose-rate factors for selected radionuclides of potential importance in radiological assessments are tabulated.