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Title: LASER TECHNOLOGY FOR PRECISION MONOENERGETIC GAMMA-RAY SOURCE R&D AT LLNL

Abstract

Generation of mono-energetic, high brightness gamma-rays requires state of the art lasers to both produce a low emittance electron beam in the linac and high intensity, narrow linewidth laser photons for scattering with the relativistic electrons. Here, we overview the laser systems for the 3rd generation Monoenergetic Gamma-ray Source (MEGa-ray) currently under construction at Lawrence Livermore National Lab (LLNL). We also describe a method for increasing the efficiency of laser Compton scattering through laser pulse recirculation. The fiber-based photoinjector laser will produce 50 {micro}J temporally and spatially shaped UV pulses at 120 Hz to generate a low emittance electron beam in the X-band RF photoinjector. The interaction laser generates high intensity photons that focus into the interaction region and scatter off the accelerated electrons. This system utilizes chirped pulse amplification and commercial diode pumped solid state Nd:YAG amplifiers to produce 0.5 J, 10 ps, 120 Hz pulses at 1064 nm and up to 0.2 J after frequency doubling. A single passively mode-locked Ytterbium fiber oscillator seeds both laser systems and provides a timing synch with the linac.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
992277
Report Number(s):
LLNL-PROC-428250
TRN: US1007724
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: IPAC 2010, Kyoto, Japan, May 23 - May 28, 2010
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; ACCURACY; AMPLIFICATION; AMPLIFIERS; BRIGHTNESS; COMPTON EFFECT; CONSTRUCTION; EFFICIENCY; ELECTRON BEAMS; ELECTRONS; FIBERS; LASERS; LAWRENCE LIVERMORE NATIONAL LABORATORY; LINEAR ACCELERATORS; OSCILLATORS; PHOTONS; SCATTERING; YTTERBIUM

Citation Formats

Shverdin, M Y, Bayramian, A, Albert, F, Anderson, S G, Betts, S M, Chu, T S, Cross, R R, Gibson, D J, Marsh, R, Messerly, M, Phan, H, Prantil, M, Wu, S, Ebbers, C, Scarpetti, R D, Hartemann, F V, Siders, C W, McNabb, D P, Bonanno, R E, and Barty, C P. LASER TECHNOLOGY FOR PRECISION MONOENERGETIC GAMMA-RAY SOURCE R&D AT LLNL. United States: N. p., 2010. Web.
Shverdin, M Y, Bayramian, A, Albert, F, Anderson, S G, Betts, S M, Chu, T S, Cross, R R, Gibson, D J, Marsh, R, Messerly, M, Phan, H, Prantil, M, Wu, S, Ebbers, C, Scarpetti, R D, Hartemann, F V, Siders, C W, McNabb, D P, Bonanno, R E, & Barty, C P. LASER TECHNOLOGY FOR PRECISION MONOENERGETIC GAMMA-RAY SOURCE R&D AT LLNL. United States.
Shverdin, M Y, Bayramian, A, Albert, F, Anderson, S G, Betts, S M, Chu, T S, Cross, R R, Gibson, D J, Marsh, R, Messerly, M, Phan, H, Prantil, M, Wu, S, Ebbers, C, Scarpetti, R D, Hartemann, F V, Siders, C W, McNabb, D P, Bonanno, R E, and Barty, C P. Tue . "LASER TECHNOLOGY FOR PRECISION MONOENERGETIC GAMMA-RAY SOURCE R&D AT LLNL". United States. doi:. https://www.osti.gov/servlets/purl/992277.
@article{osti_992277,
title = {LASER TECHNOLOGY FOR PRECISION MONOENERGETIC GAMMA-RAY SOURCE R&D AT LLNL},
author = {Shverdin, M Y and Bayramian, A and Albert, F and Anderson, S G and Betts, S M and Chu, T S and Cross, R R and Gibson, D J and Marsh, R and Messerly, M and Phan, H and Prantil, M and Wu, S and Ebbers, C and Scarpetti, R D and Hartemann, F V and Siders, C W and McNabb, D P and Bonanno, R E and Barty, C P},
abstractNote = {Generation of mono-energetic, high brightness gamma-rays requires state of the art lasers to both produce a low emittance electron beam in the linac and high intensity, narrow linewidth laser photons for scattering with the relativistic electrons. Here, we overview the laser systems for the 3rd generation Monoenergetic Gamma-ray Source (MEGa-ray) currently under construction at Lawrence Livermore National Lab (LLNL). We also describe a method for increasing the efficiency of laser Compton scattering through laser pulse recirculation. The fiber-based photoinjector laser will produce 50 {micro}J temporally and spatially shaped UV pulses at 120 Hz to generate a low emittance electron beam in the X-band RF photoinjector. The interaction laser generates high intensity photons that focus into the interaction region and scatter off the accelerated electrons. This system utilizes chirped pulse amplification and commercial diode pumped solid state Nd:YAG amplifiers to produce 0.5 J, 10 ps, 120 Hz pulses at 1064 nm and up to 0.2 J after frequency doubling. A single passively mode-locked Ytterbium fiber oscillator seeds both laser systems and provides a timing synch with the linac.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Apr 20 00:00:00 EDT 2010},
month = {Tue Apr 20 00:00:00 EDT 2010}
}

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  • We report the design and current status of a monoenergetic laser-based Compton scattering 0.5-2.5 MeV {gamma}-ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented. At MeV photon energies relevant for nuclear processes, Compton scattering light sources are attractive because of their relative compactness and improved brightness above 100 keV, compared to typical 4th generation synchrotrons. Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable Mono-Energetic Gamma-Ray (MEGa-Ray) light sources based on Compton scattering between a high-brightness, relativistic electron beam and a highmore » intensity laser pulse produced via chirped-pulse amplification (CPA). A new precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. Based on the success of the previous Thomson-Radiated Extreme X-rays (T-REX) Compton scattering source at LLNL, the source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. After a brief presentation of successful nuclear resonance fluorescence (NRF) experiments done with T-REX, the new source design, key parameters, and current status are presented.« less
  • A new class of tunable, monochromatic {gamma}-ray sources capable of operating at high peak and average brightness is currently being developed at LLNL for nuclear photoscience and applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector. A prototype, capable of producing > 10{sup 8} 0.7 MeV photons in a single shot, with a fractional bandwidth of 1%, and a repetition rate of 10 Hz, is currently under construction at LLNL; this system will be used to perform nuclear resonance fluorescence experiments. A new symmetrized S-bandmore » rf gun, using a Mg photocathode, will produce up to 1 nC of charge in an 8 ps bunch, with a normalized emittance modeled at 0.8 mm.mrad; electrons are subsequently accelerated up to 120 MeV to interact with a 500 mJ, 10 ps, 355 nm laser pulse and generate {gamma}-rays. The laser front end is a fiber-based system, using corrugated-fiber Bragg gratings for stretching, and drives both the frequency-quadrupled photocathode illumination laser and the Nd:YAG interaction laser. Two new technologies are used in the laser: a hyper-Michelson temporal pulse stacker capable of producing 8 ps square UV pulses, and a hyper-dispersion compressor for the interaction laser. Other key technologies, basic scaling laws, and recent experimental results will also be presented, along with an overview of future research and development directions.« less