Difference between revisions of "Commissioning Run Plan"

Revision as of 17:03, 13 October 2014

For the Fall of 2014 assume:

• Maximum beam current = 20 μA but for short times it can go higher for boiling studies and BCM calibration.
• 7.3 GeV @ 4 pass, 5.5GeV @ 3 Pass and 3.7 GeV @ 2 pass. No five pass beam in the Fall of 2014.
• Angle restrictions with DVCS calorimeter in place:
  1. HRS-BL: 26.5 to 45 degrees
  2. HRS-BR: 46.2 to 74.5 degrees

Pre-beam Checklist

Trigger Checkout (Experts)

* Checkout trigger timing
* Checkout of EDTM (Barak Schmookler)
* Think about adding 60, 100, 150, and 200 ns wide electronic deadtime scalers.
  This has been found to be a robust method for determining electronic deadtime in Hall C and we should think about adding something similar for GMP.

HRS Detector Checkout (Detector Experts)

* Take a long cosmics run with all detectors on.
* Look for dead and hot wires in the wire chambers against an earlier plot to look for any possible inconsistencies in wiring.  Check these against 
  those listed in the current analysis parameters. (Yang Wang)
* Look at ADC distributions for the hodoscopes Gas Cherenkovs and lead glass calorimeters.  Are they all firing? (Barak Schmookler, Longwu Ou)
* Look at TDC distributions for hodoscopes and Gas Cherenkovs.  Is the timing reasonable, any multiple peaks, within timing range, etc? 
  (Barak Schmookler, Longwu Ou)

Commissioning and Calibrations

The following items should be performed during the first 1-1.5 shifts:

* Initial trigger checkout with beam.  Check timing and PID thresholds.
* Initial detector checkout with beam.
* Initial checks of beam position and raster.

The detector checkout is best done using a fairly uniform illumination, which is provided for by 20 μA on the central Carbon target at the following kinematics:

E' = 2.0 GeV, θ = 30 degrees (W² = 3.03 GeV, Q² = 2.36 GeV²). The HRS electron rates should be about 800 Hz.

Beamline

Spectrometer Optics

• Time estimate: 1-2 hours

Procedure with Sieve-slit

* A Hall A Tech may be required to install the sieve-slit collimator onto the front face of the HRS.
* Take a sieve slit run with the multi-foil carbon target for the inelastic kinematics in the table.
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
* Repeat the above with the beam position shifted so that you see a vertical shift by one row.
* Rates assume 5 carbon foils, only 9 out of 25 sieve holes have events (~ 0.146 mSr acceptance), and 9% delta acceptance.

Procedure without Sieve-slit

* Next take a run at the following kinematics without the sieve-slit collimator.
* If you need to increase the spectrometer momentum setting, make sure you cycle Q2 and Q3 as per the cycling procedure.
* Rates assume 5 carbon foils, 6 mSr acceptance, and 9% delta acceptance.

Elastic from Hydrogen

Elastic electron-proton measurement. Assuming a 15 cm LH2 target, a spectrometer acceptance of 6 msr and dipole form factor to compute the central cross-section. Taking data at 7.3 GeV with the given angle restrictions is time consuming.
(Table borrowed from DVCS3 wiki page)