Schematic of nuclear resonance fluorescence. An incident gamma-ray excites a nucleus from the ground state (angular momentum ) to the excited state (angular momentum ). is the partial width for the direct gamma-ray transition to the ground state. The nucleus relaxes back to the ground state by emitting a photon of characteristic energy.
General architecture of the Compton scattering source being built at LLNL. It will include an X-band linac powered bymodulators and klystrons and two laser systems. The PDL produces the electrons on the photocathode and the ILS collides with the electron beam at the interaction point to yield gamma-rays.
Nominal electron beam parameters (top) and corresponding gamma-ray spectrum. The electron beam has a normalized emittance of 0.34 mm mrad at 163 MeV, a 0.16% energy spread and a 7.24 μm rms focus. The laser has a 1064 nm wavelength, a 0.15 J energy and a 10 μm (FWHM) focus.
Comparison of gamma-ray spectra for different laser energies. For all three cases, the electron beam parameters are mm mrad, and the rms focal spot is 28.9 μm. The laser focal spot and duration are 18.6 μm and 10 ps for each case and the laser energies are 0.15 J, 0.3 J, and 1 J (blue, green, and red) which correspond, respectively, to 0.06, 0.09, and 0.16.
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