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S. M. Betts

First Name: S.

Middle Name: M.

Last Name: Betts

Full Name: S. M. Betts

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4 papers
 title: Nuclear Photo-Science And Applications with Thomson-Radiated Extreme X-Ray (T-Rex) Sources format: conference proceeding conference: Linear Accelerator Conference 2006 year: 2006 15 authors: | | | | | | | | | | | | | | abstract: Recent advances in high brightness rf gun technology, coupled with novel laser systems and architecture have enabled the development of a new class of compact, tunable, monochromatic light sources capable of producing MeV photons with unprecedented brightness. Such new sources rely on Thomson scattering of incident photons produced by a TW-class laser off a bright relativistic electron beam to generate Doppler-upshifted photons in a highly collimated beam. Scaling laws [1] show that a frequency-doubled, 532 nm wavelength, 1 J, 10 ps Fourier transform-limited drive laser pulse interacting with a 250 MeV, 1 nC, 10 ps, 1 mm.mrad normalized emittance, with 0.1% relative energy spread, can yield a 2.24 MeV ?-ray flash with a peak brightness exceeding 1023 photons/[mm2 x mrad2 x s x 0.1% bandwidth]. This number is > 15 orders of magnitude beyond the output of a third-generation synchrotron at the same photon energy. Above ~ 100 keV, the photons can interact with nuclei, and nuclear applications become viable. In this paper, we present a technical overview of T- REX sources and their capabilities, and give a few examples of potential applications of interest. keywords: pbpl Download | Details | Edit | Delete
 title: Production of High Harmonic X-ray Radiation from Non-linear Thomson Scattering at LLNL PLEIADES format: conference proceeding conference: PAC 2005 year: 2005 11 authors: | | | | | | | | | | abstract: We describe an experiment for production of high harmonic x-ray radiation from Thomson backscattering of an ultra-short high power density laser by a relativistic electron beam at the PLEIADES facility at LLNL. In this scenario, electrons execute a figure-8'' motion under the influence of the high-intensity laser field, where the constant characterizing the field strength is expected to exceed unity: $a_{L}=eE_{L}/m_{e}c\omega_{L}\geq1$. With large $a_{L}$ this motion produces high harmonic x-ray radiation and significant broadening of the spectral peaks. This paper is intended to give a layout of the PLEIADES experiment, along with progress towards experimental goals. keywords: Download | Details | Edit | Delete
 title: HIgh Energy, High Brightness X-Rays Produced by Compton Back Scattering at the Livermore PLEIADES facility format: conference proceeding conference: PAC 2005 year: 2005 11 authors: | | | | | | | | | | abstract: PLEIADES (Picosecond Laser Electron Interaction for the Dynamic Evaluation of Structures) produces tunable 30-140 keV x-rays with 0.3-5 ps pulse lengths and up to 10^7 photons/pulse by colliding a high brightness electron beam with a high power laser. The electron beam is created by an rf photo-injector system, accelerated by a 120 MeV linac, and focused to 20 ?m with novel permanent magnet quadrupoles. To produce Compton back scattered x-rays, the electron bunch is overlapped with a Ti:Sapphire laser that delivers 500 mJ, 100 fs, pulses to the interaction point. K-edge radiography at 115 keV on Uranium has verified the angle correlated energy spectrum inherent in Compton scattering and high-energy tunability of the Livermore source. Current upgrades to the facility will allow laser pumping of targets synchronized to the x-ray source enabling dynamic diffraction and time-resolved studies of high Z materials. Near future plans include extending the radiation energies to >400 keV, allowing for nuclear fluorescence studies of materials. keywords: pbpl Download | Details | Edit | Delete
 title: Experimental characterization of an ultrafast Thomson scattering x-ray source with three-dimensional time and frequency-domain analysis format: journal article publisher: year: 2004 18 authors: | | | | | | | | | | | | | | | | | abstract: We present a detailed comparison of the measured characteristics of Thomson backscattered xrays produced at the Picosecond Laser-Electron Interaction for the Dynamic Evaluation of Structures facility at Lawrence Livermore National Laboratory to predicted results from a newly developed, fully three-dimensional time and frequency-domain code. Based on the relativistic differential cross section, this code has the capability to calculate time and space dependent spectra of the x-ray photons produced from linear Thomson scattering for both bandwidth-limited and chirped incident laser pulses. Spectral broadening of the scattered x-ray pulse resulting from the incident laser bandwidth, perpendicular wave vector components in the laser focus, and the transverse and longitudinal phase spaces of the electron beam are included. Electron beam energy, energy spread, and transverse phase space measurements of the electron beam at the interaction point are presented, and the corresponding predicted x-ray characteristics are determined. In addition, time-integrated measurements of the xrays produced from the interaction are presented and shown to agree well with the simulations. keywords: pbpl Download | Details | Edit | Delete