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Archived Messages for HALLB_1997@cebaf.gov: Missing photons found!
Missing photons found!
CALCOM@CEBAF.GOV
Sat, 13 Sep 1997 12:48:21 -0500 (EST)
When the vacuum system was opened at the end of the photon run on Sept. 7,
a major obstruction was found in the photon beam path, explaining the
poor tagging efficiencies reported at the Collaboration meeting.
A one-night test run was organized for Sept. 12-13. Preliminary
analysis of the new data yields a tagging efficiency (corrected for
pair production in the air path) above 95% for the full focal plane,
and no evidence for contamination by low-energy photons.
Many thanks to Arne for organizing the run, and to all those who
participated at short notice. Now onward to g1!
Dan Sober