Transcript ppt
GLAST LAT Project
CERN PS Runtime Estimates
Beam Test VRVS
April 4, 2006
Gary Godfrey
[email protected]
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GLAST LAT Project
Run Time for Draft Beam Test Plan (Jan 2006)
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GLAST LAT Project
Runtime for Gary’s Suggested Runs
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GLAST LAT Project
Comments
1)
We do not have enough beam time to tag every energy photon (20 Mev to 2.5
Gev) at evergy angle and position that we wish to run.
2)
Therefore, use the full Brems spectrum (Ebeam=2.5 GeV) on every run by using
the calibrated CsI calorimeter to put the photons into energy bins.
a)
b)
Use beam electrons to calibrated the CsI for E> 1 GeV
Use tagged photons (1 GeV beam) to calibrate the CsI for E< 1 GeV
3)
Let the tagger read out when ever it sees a electron during the 2.5 GeV running
(will tag 1.5 to 1.9 GeV photons). Tagger writes a blank record (how long does
this take?) when there is a CU trigger but no tagger read out.
4)
Si tagger sits as close as possible to the bend magnet, but not so close that the
magnet fringe field bends the tracks from a straight line in the downstream Si
telescope. This close position maximizes the momentum bite of the tagger.
5)
Never move the Si tagger. Never change B. It is possible to place the Si at a
reasonable (~11 cm) distance from the beam axis such that an unradiated 1
GeV beam hits the Si inner edge (for B=10 Kgauss). The tagger is now
calibrated and will measure E <= 1 GeV radiated beam when Ebeam=2.5 GeV.
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GLAST LAT Project
Pollution by Double Brems in the Radiator
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GLAST LAT Project
Pollution by Double Brems versus Radiator Thickness
The radiator thickness is the sum of:
1) Cherenkov windows and gas
2) Scintillator
3) Upstream Tagger telescope (2 windows + 4 Si detectors)
Desired
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GLAST LAT Project
Tagger Photon Resolution for 1 GeV Beam
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