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Jason, A.J.

Paper Title Page
TPPT088 Power Dependence of the RF Surface Resistance of MgB2 Superconductor 4215
 
  • T. Tajima, A. Findikoglu, A.J. Jason, F.L. Krawczyk, F. M. Mueller, A. H. Shapiro
    LANL, Los Alamos, New Mexico
  • R.L. Geng, H. Padamsee, A.S. Romanenko
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • B. Moeckly
    STI, Santa Barbara, California
 
  MgB2 is a superconducting material that has a transition temperature (Tc) of ~40 K. Recently, it has been shown at 4 K, liquid helium temperature, that the surface RF resistance can be lower than Nb that has the Tc of 9.2 K and has been used for most superconducting RF cavities in the past decades. One of the problems with other high-Tc materials such as YBCO was its rapid increase in RF surface resistance with higher surface magnetic fields. Recently, we have shown that MgB2 shows little increase up to about 120 Oe, equivalent of an accelerating field of about 3 MV/m. The highest field tested was limited by available power. This result is encouraging and has made us consider fabricating a cavity coated with MgB2 and test it. Also, there might be a potential that this material has a higher critical magnetic field that enables the cavity to run at a higher gradient than Nb cavities.  
WOAC002 Chromatically Corrected Imaging Systems for Charged-Particle Radiography 225
 
  • B. Blind, A.J. Jason
    LANL, Los Alamos, New Mexico
 
  In proton radiography, imaging with systems consisting of quadrupole magnets is an established technique for viewing the material distribution and composition of objects, either statically or during fast events such as explosions. With the most favorable magnet configuration, the –I lens, chromatic aberrations generally dominate the image blur. Image resolution can be improved, and largely decoupled from the input-beam parameters, by using a second-order achromatic bend with some additional higher-order aberration correction. The aberration-correction approach is discussed. For a given resolution, such a bend allows use of much lower-energy imaging particles than a –I lens. Each bend design represents a set of equivalent systems; an 800-MeV proton design and its equivalent 40-MeV electron system are presented. The electron system is useful for imaging small objects. Magnet errors in the achromatic bends must be tightly controlled to preserve image quality, but not beyond feasibility of present technology. System performance is verified by particle tracking. Configurations alternative to the canonical achromatic bend are also discussed.  
RPPT068 Pion-Muon Concentrating System for Detectors of Highly Enriched Uranium 3757
 
  • S.S. Kurennoy, D.B. Barlow, B. Blind, A.J. Jason, N. Neri
    LANL, Los Alamos, New Mexico
 
  One of many possible applications of low-energy antiprotons collected in a Penning trap can be a portable muon source. Released antiprotons annihilate on impact with normal matter producing on average about 3 charged pions per antiproton, which in turn decay into muons. Existence of such negative-muon sources of sufficient intensity would bring into play, for example, detectors of highly enriched uranium based on muonic X-rays. We explore options of collecting and focusing pions and resulting muons to enhance the muon flux toward the detector. Simulations with MARS and MAFIA are used to choose the target material and parameters of the magnetic system consisting of a few solenoids.