AVS 46th International Symposium
    Vacuum Technology Division Tuesday Sessions
       Session VT-TuP

Paper VT-TuP13
Photon Stimulated Desorption Measurements of Copper Beam Chambers for the KEKB Collider@Footnote 1@

Tuesday, October 26, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: C.L. Foerster, Brookhaven National Laboratory
Authors: C.L. Foerster, Brookhaven National Laboratory
C. Lanni, Brookhaven National Laboratory
K. Kanazawa, KEK, Japan
K. Shimotsuma, KSA Inc.
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KEKB is an asymmetrical collider constructed for the High Energy Accelerator Research Organization(KEK) in Ibaraki, Japan. The new collider utilizes two UHV ring chambers, one for a 3.5 GeV positron beam and the other for an 8 GeV electron beam, to study B-mesons. Two Samples, each one (1) meter long, of KEKB beam chambers were studied on newly constructed beamline U9a at the National Synchrotron Light Source (NSLS). Copper was chosen by KEK for the chamber construction material as it withstands high peak heat loads and also serves as a radiation shield. The samples have a circular cross section of 94mm inner diameter. After cleaning, flanges were electron-beam welded to the ends of the samples, and then the assembly was shipped to the NSLS, for installation in the PSD set up. Once sucessfully leak tested, the sample was installed in U9a, exposed to more than 10@super 23@ photons direct from the source at a critical energy of 595 eV, striking the sample at an incident angle of 100mrad. The major PSD yields for hydrogen, carbon monoxide, carbon dioxide, methane, and water vapor are reported as a funtion of accumulated photon flux and sample preparation. The results are compared with other PSD measurements on NSLS beamlines U9a, U10b, X28a, and those of other laboratories published for copper. @FootnoteText@ @Footnote 1@ Work performed under auspices of the U.S. Department of Energy, under contract DE-AC02-76CH00016.