HRS Checkout (Experts)
The detector checkout is best done using a fairly uniform illumination, which is provided for by 20 μA on the optics target at the following kinematics:
The Right HRS electron rates should be about 119 Hz, and the left HRS electron rates should be about 9.8 kHz.
Make sure to adjust the prescale factors to obtain a reasonable deadtime < 10%.
|HRS||Ebeam [GeV]||P0 [GeV/c]||θe [deg]||Collimator||Target||Fast Raster
X x Y
|Right||2.217||0.85||48.75||None||Optics||2 x 2 mm2||20 μA||S0&&S2m|
|Left||2.217||1.0||17.5||None||Optics||2 x 2 mm2||20 μA||S0&&S2m|
- With the above kinematics, take a run (at least 200K electrons or 30 minutes) and verify that all detector channels are working.
- Using the same run, produce a ROOT tree, and do the following: make a spectrum of x vs. y at the focal plane. What you should see is a "spider" with 5 legs. The non-straightness of the central legs indicates there is an offset in the Z or Y direction. If you don't see a "spider" or something resembling it, then of of the polarities of the HRS magnets is set wrong (or a magnet is off).
- Check that the signals are well timed.
- Determine correct thresholds.
- Verify all scalers are incrementing.
- Check for double pulsing and time the wire chamber signals.
- Are the scintillator signals on scale in the ADCs?
- PID threshold checks.