Prad tgt for tac

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Low-density gas radiator for TAC runs.

  • PRad windowless low-density gas target:
    • Gas flow, with two holed kapton 7.5 um windows (holes: 2mm diam.) and two turbomolecular pumps to maintain vaccum in the pipes before and after the target.
    • 10^-7 (PRad operation: low temperature: 20K, H2 gas. 10^18 H2/cm^2)
    • 4cm length
    • Can be operated at hall temperature with higher-z innert gas (N2, Ar). Would result in similar thickness. Can use bigger capton holes if halo is too large.
    • Gas flow (i.e. target thickness) can be controlled.
    • Could use standard production beam current of a few 100s nA.
    • Best location to install it: AD00 current location just upstream the goniometer. PRad target chamber currently too bulky to be installed in tunnel. Also, this would compromise tagger data. Modification of target chamber would cost ~$50K.
    • Density known at ~10% level for PRad operation.
  • Discussed with Todd Satogata: No objection to install the target at the AD00 nA-BPM location. AD00 would be moved 1 to 2 m just upstream 5C11B at the end of the tunnel. (It could also could be just removed). This would degrade somewhat the quality of the fast feedback (not an issue for Hall D at the moment). Waiting for confirmation from Trent Allison that there is no issue with moving AD00.
  • Discuss with C. Keith. no problems with:
    • Installing the target in Hall D tagger vault,
    • Running it warm,
    • Running it with any type of gas.
  • Discussed with Alex Somov, Hovanes and Eugene: Agree that this should help with TAC runs: Wire radiator could have the right thickness, but samples only specific area of the beam.
  • Contacted Ashot: Likes the idea. But need to discuss with other members of PRad. Also, would like to have priority of use in case new PRad-like experiments are scheduled (their D-radius proposal for PAC45 was deferred but they will try again). C. Keith: No issue about de-installing/re-installing this type of target.

Links to PRad target pages: