• F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.E. Bonnanno, T.S. Chu, R.R. Cross, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, D.P. McNabb, M. J. Messerly, R.D. Scarpetti, M. Shverdin, C. Siders, S.S.Q. Wu
  LLNL, Livermore, California
• C. Adolphsen, A.E. Candel, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
  SLAC, Menlo Park, California
• V.A. Semenov
  UCB, Berkeley, California

Continued progress in accelerator physics and laser technology have enabled the development of a new class of tunable x-ray and gamma-ray light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable, monochromatic (< 0.4% rms spectral width) source driven by a compact, high-gradient X-band linac designed in collaboration with SLAC is under construction at LLNL. High-brightness (250 pC, 3.5 ps, 0.4 mm.mrad), relativistic electron bunches will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable γ-rays in the 0.5-2.5 MeV photon energy range. This gamma-ray source will be used to excite nuclear resonance fluorescence in various isotopes. Fields of endeavor include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status will be discussed, along with important applications, including nuclear resonance fluorescence and high precision medical imaging.

• K.W. Jones, J.L. Erickson, R.W. Garnett, M.S. Gulley
  LANL, Los Alamos, New Mexico

The Los Alamos Neutron Science Center (LANSCE) accelerator and beam delivery complex generates the proton beams that serve three neutron production sources, a proton radiography facility and a medical and research isotope production facility. The recent operating history of the facility, including both achievements and challenges, will be reviewed. Plans for performance improvement will be discussed, together with the underlying drivers for the ongoing LANSCE Life Extension project. The details of this latter project will also be discussed.

• F. Roncarolo, E. Bravin, M. Duraffourg, C. Dutriat, G.J. Focker, U. Raich, VC. Vuitton
  CERN, Geneva
• B. Cheymol
  Université Blaise Pascal, Clermont-Ferrand

As part of the CERN LHC injector chain upgrade, LINAC4 will accelerate H^- ions from 45 keV to 160 MeV. A number of wire grids and wire scanners will be used to characterize the beam transverse profile. This paper covers all monitor design aspects intended to cope with the required specifications. In particular, the overall measurement robustness, accuracy and sensitivity must be satisfied for different commissioning and operational scenarios. The physics mechanisms generating the wire signals and the wire resistance to beam induced thermal loads have been considered in order to determine the most appropriate monitor design in terms of wire material and dimensions.

• K.L.F. Bane, C. Adolphsen, C.D. Nantista
  SLAC, Menlo Park, California

The superconducting cavities and interconnects in the 12 km long linacs of the International Linear Collider (ILC) are designed to operate at 2K where cooling costs are very expensive. Thus it is important to ensure that any additional cryogenic heat loads are small in comparison to those from static losses and the fundamental 1.3 GHz accelerator mode. One potential heat source is the higher order modes (HOM) excited by the beam. Such modes will be damped by specially designed HOM couplers that are attached to the cavities (for trapped modes), and by 70K ceramic dampers that are located in each of the eight or nine cavity cryomodules (for propagating modes). Brute force calculations of the higher frequency, non-trapped modes excited in a string of cryomodules is limited by computing capacity. We present, instead, an approach that combines scattering matrix and wakefield calculations to study the effectiveness of the dampers in limiting the heat deposited in the 2K cryogenic system.

• M. Panniello, V.G. Vaccaro
  Naples University Federico II and INFN, Napoli
• M.R. Masullo
  INFN-Napoli, Napoli

The Wire Method for Coupling Impedance evaluations is quite appealing for the possibility to make bench measurements on the Device Under Test (DUT). However, it is not entirely reliable because the stretched wire perturbs the boundary conditions, introducing a TEM wave that has a zero cut off frequency. We expect that, for frequencies smaller than the cutoff one, this behaviour produces an additional power loss which drastically lowers the high Q resonances of DUT. Above cutoff frequency, the impact of the stretched wire is not as dramatic as below cutoff. The Mode Matching Technique will be used to simulate the measurement with the Wire Method. In this way one may get a result which is not affected by the errors intrinsic of experimental measurements. The same method will be used to get, according to its standard definition, the Coupling Impedance of the real structure. The two results will be compared in order to define the frequency ranges in which they agree or disagree. As expected large discrepancies appear below cutoff frequency, while above cutoff, for certain ranges of parameters, an agreement is found.