2011 Particle Accelerator Conference - List of Authors (Messerly, M. J.)

Paper	Title	Page
THP222	Drive Laser System for the Advanced Photo-Injector Project at the LBNL	2537
	J. Feng, D. Filippetto, H.A. Padmore, F. Sannibale, R.P. Wells LBNL, Berkeley, California, USA M. J. Messerly, M.A. Prantil LLNL, Livermore, California, USA
	Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231. The electron photo-gun of the Advanced Photo-injector EXperiment project (APEX) at the LBNL will be driven by a compact fiber laser for different photo-cathode experiments during the initial phase of the project. The fiber laser, developed at the Lawrence Livermore National Laboratory, is designed to deliver μJ/pulse at 10⁶⁴ nm system that is frequency doubled to deliver light at 532nm with 1MHz repetition rate and 1ps pulse length optimized for photo-emission with multi-alkali antimonide cathodes. For Cs2Te and diamond amplifier cathodes, the 4th harmonic will be generated by doubling frequency again in a non-linear crystal. Due to the requirement of small emittance for the electron beam, the laser pulse will be shaped in space and time for 532nm and UV lights, in general with a constant intensity in cross section with a sharp radial cutoff, and elliptical or rectangular distribution in the longitudinal plane. Diagnostics of the laser beam itself and of the cathode will be integrated with techniques such as cross- correlation, streak camera, and virtual cathode imaging, not only to monitor the laser pulse but also to provide automated feedbacks.

THP223	Laser Systems for Livermore's Mono-Energetic Gamma-Ray Source	2540
	D.J. Gibson, F. Albert, C.P.J. Barty, A.J. Bayramian, C.A. Ebbers, F.V. Hartemann, R.A. Marsh, M. J. Messerly LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. A Mono-energetic Gamma-Ray (MEGa-Ray) source, based on Compton scattering of a high-intensity laser beam off a highly relativistic electron beam, requires highly specialized laser systems. To minimize the bandwidth of the gamma-ray beam, the scattering laser must have minimal bandwidth, but also match the electron beam depth of focus in length. This requires a ~1 J, 10 ps, fourier-transform-limited laser system. Also required is a high-brightness electron beam, best provided by a photoinjector. This electron source in turn requires a second laser system with stringent requirements on the beam including flat transverse and longitudinal profiles and fast rise times. Furthermore, these systems must be synchronized to each other with ps-scale accuracy. Using a novel hyper-dispersion compressor configuration, advanced fiber amplifiers, and diode-pumped Nd:YAG amplifiers, we have designed laser systems that meet these challenges for the x-band photoinjector and Compton-scattering source being built at Lawrence Livermore National Laboratory.

THP181	Low Intensity Nonlinear Effects in Compton Scattering Sources	2453
	F. Albert, S.G. Anderson, C.P.J. Barty, M. Betts, R.R. Cross, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh, M. J. Messerly, C. Siders, S.S.Q. Wu LLNL, Livermore, California, USA
	The design and optimization of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. In particular, while it is known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

THP182	Overview of Current Progress on the LLNL Nuclear Photonics Facility and Mono-energetic Gamma-ray Source	2456
	F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, D.P. McNabb, M. J. Messerly, C. Siders LLNL, Livermore, California, USA C. Adolphsen, T.S. Chu, E.N. Jongewaard, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang SLAC, Menlo Park, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 A new class of gamma-ray light source based on Compton scattering is made possible by recent progress in accelerator physics and laser technology. Mono-energetic gamma-rays are produced from collisions between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A 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 linear accelerator 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. The source will be used to conduct nuclear resonance fluorescence experiments and address a broad range of current and emerging applications in nuclear photoscience. Users include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications.

Paper

Title

Page

Drive Laser System for the Advanced Photo-Injector Project at the LBNL

2537

J. Feng, D. Filippetto, H.A. Padmore, F. Sannibale, R.P. Wells
LBNL, Berkeley, California, USA
M. J. Messerly, M.A. Prantil
LLNL, Livermore, California, USA

Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
The electron photo-gun of the Advanced Photo-injector EXperiment project (APEX) at the LBNL will be driven by a compact fiber laser for different photo-cathode experiments during the initial phase of the project. The fiber laser, developed at the Lawrence Livermore National Laboratory, is designed to deliver μJ/pulse at 10⁶⁴ nm system that is frequency doubled to deliver light at 532nm with 1MHz repetition rate and 1ps pulse length optimized for photo-emission with multi-alkali antimonide cathodes. For Cs2Te and diamond amplifier cathodes, the 4th harmonic will be generated by doubling frequency again in a non-linear crystal. Due to the requirement of small emittance for the electron beam, the laser pulse will be shaped in space and time for 532nm and UV lights, in general with a constant intensity in cross section with a sharp radial cutoff, and elliptical or rectangular distribution in the longitudinal plane. Diagnostics of the laser beam itself and of the cathode will be integrated with techniques such as cross- correlation, streak camera, and virtual cathode imaging, not only to monitor the laser pulse but also to provide automated feedbacks.

THP223

Laser Systems for Livermore's Mono-Energetic Gamma-Ray Source

2540

D.J. Gibson, F. Albert, C.P.J. Barty, A.J. Bayramian, C.A. Ebbers, F.V. Hartemann, R.A. Marsh, M. J. Messerly
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
A Mono-energetic Gamma-Ray (MEGa-Ray) source, based on Compton scattering of a high-intensity laser beam off a highly relativistic electron beam, requires highly specialized laser systems. To minimize the bandwidth of the gamma-ray beam, the scattering laser must have minimal bandwidth, but also match the electron beam depth of focus in length. This requires a ~1 J, 10 ps, fourier-transform-limited laser system. Also required is a high-brightness electron beam, best provided by a photoinjector. This electron source in turn requires a second laser system with stringent requirements on the beam including flat transverse and longitudinal profiles and fast rise times. Furthermore, these systems must be synchronized to each other with ps-scale accuracy. Using a novel hyper-dispersion compressor configuration, advanced fiber amplifiers, and diode-pumped Nd:YAG amplifiers, we have designed laser systems that meet these challenges for the x-band photoinjector and Compton-scattering source being built at Lawrence Livermore National Laboratory.

THP181

Low Intensity Nonlinear Effects in Compton Scattering Sources

2453

F. Albert, S.G. Anderson, C.P.J. Barty, M. Betts, R.R. Cross, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh, M. J. Messerly, C. Siders, S.S.Q. Wu
LLNL, Livermore, California, USA

The design and optimization of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. In particular, while it is known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

THP182

Overview of Current Progress on the LLNL Nuclear Photonics Facility and Mono-energetic Gamma-ray Source

2456

F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, D.P. McNabb, M. J. Messerly, C. Siders
LLNL, Livermore, California, USA
C. Adolphsen, T.S. Chu, E.N. Jongewaard, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang
SLAC, Menlo Park, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
A new class of gamma-ray light source based on Compton scattering is made possible by recent progress in accelerator physics and laser technology. Mono-energetic gamma-rays are produced from collisions between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A 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 linear accelerator 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. The source will be used to conduct nuclear resonance fluorescence experiments and address a broad range of current and emerging applications in nuclear photoscience. Users include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications.