Pion-LT specific shift instructions
- Make sure to follow the appropriate magnet cycling procedure for the HMS and SHMS magnets
- When the SHMS is at 10 degrees or below, ask for beam off when cycling magnets
- Make sure to record all angles to 2 digits using the marks on the floor.
- It should be possible to set the spectrometers to within 0.01 degree of the desired value without too much difficulty. If this is a problem, then set the angle to within 0.03 degree of what is requested, but make a clear record of the actual setting in the hclog.
- Please make an elog entry with an image of the angles on the camera every time you do a rotation.
- We would like to control both the position and angle of the beam on target. Unless specified otherwise, please ensure that MCC puts the beam at the nominal position (written on the white board) for both the 3H07A and 3H07C BPMs.
- Single particle and coincidence rates have been estimated for all runs. Watch the scintillator rates (S1 and 3/4 planes) for each spectrometer for an indication of the particle rate through the wire chambers, and if actual rate is substantially (> 50%) higher than what is listed in the run plan, the RC should be warned.
- We want to keep the particle rate in each spectrometer below 650 kHz, and for some low energy runs this will require the beam current to be reduced from the nominal 70 μA value.
- For some low rate runs, it may be possible to use up to 100 μA beam with particle rates still below 350 kHz. Consult with the RC before requesting a higher beam current.
- The prescale values in the run plan are a guide. Adjust them to keep the singles data rate in each spectrometer between ∼100-150 Hz.
- If you change the prescalers, you must update and apply them in the GUI before you start a new run
- All run times assume 100% running efficiency. Adjust the time for actual delivered beam time, and let the RC know if the efficiency drops below 60% for an extended period.
- Detector check replay to be done on first 50,000 events of every run, and compare plots with the standard ones in the binder. In addition, we want physics replay to be done on every run in its entirety. pi+ plots such as missing mass, t, W, Q^2 and phi should be checked for anomalies. Full replay instructions available here.
- Do not start the full analysis until after the run ends!
- Keep standard.kinematics up to date with the spectrometer settings for every configuration, so that the physics replay generates meaningful quantities. Use the beam energy determined from the arc measurement in the file, and the spectrometer angles from the TV.
- For aluminium dummy target runs, do not set the target mass to be aluminium in standard.kinematics, it should be the mass of hydrogen still!
- Shift leaders are asked to keep a running total of the number of e-Pi coincidence events falling within the missing mass and fiducial volume cuts set in the physics replay script, so that we can better estimate when to move to the next setting.