Matt, Someone should do a rough scaling argument here. The Radphi hole was 3x3. The detector was 1.02m from the target. Even if we keep the hole size the same at 3x3, moving it downstream with rate ~ 1/r^3 means that the rate scales like distance from the target (3 powers for decreased angle - 2 powers for decreased solid angle = 1 power of distance): we should have a factor 6 worse exposure rate in gluex than we had in Radphi for the blocks around the beam hole, at the same beam intensity. As I recall, gluex at 10^8 is the same as the Radphi normal running intensity, within 30%, as far as beam bg is concerned. Richard J. Matthew Shepherd wrote: > Why? If I remember from Richard, the angular dependence is like > 1/theta^3 which corresponds to basically 1/r^3. You can look at the > plot -- remember it is a logarithmic scale.
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