Coherent Bremsstrahlung from the g8 run'

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Coherent Bremsstrahlung from the g8 run. J.D.
Kellie K. Livingston University of
Glasgow U.K. 1. General Remarks. C.B.
production. Diamond Crystal alignment. 2. G8
run. Hall-B linearly polarised tagged photon
facility. Goniometer and diamond crystal. C.B.
spectra. Estimate of degree of linear
polarisation. 3. Comments. 4. Implications for
Hall-D.
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3. Comments. a) Electron beam is of necessary
quality. b) Diamond/goniometer provided
convincing C.B. spectra. c) Instability of C.B.
edge. Crystal mounting? Beam movement across
curved crystal surface? d) Unrealistic parameters
required to obtain good match between calculated
and measured spectra. e) Need to measure
electron beam emittance independently. f) Performa
nce of tagger E-counters unacceptable. g) Systemat
ic evaluation of C.B. production is being carried
out as part of g8 analysis. h) Effect of photon
collimator has still to be evaluated.
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4. Implications for Hall-D. 1. Need for a
broad-band tagger. a) Accurate crystal
alignment. b) On-line monitoring of C.B.
spectrum. c) Evaluation of degree of linear
poarisation. d) More versatile facility. 2.
Mounting of thin diamond crystals. 3. Tests
using Hall-B facility. (E-counter scalers
only.) a) C.B. edge stability - 20 50 micron
crystals. b) C.B. spectrum shape. c) Photon flux
measurements before and after photon collimator.