Run Plan for Kaon LT Luminosity Scan

Goal

The electrons in the HMS will be used to monitor cryotarget boiling, while the positive polarity SHMS will be used to investigate the reliability of hadron tracking efficiencies at high rates. We will use three different targets:

• standard 10cm LH₂
• C (z=1.5% RL) - maximum current 65uA
• Al dummy - maximum current 40uA

Initial Setup

1. Set PS1 and PS3 DAQ rates to 1.5kHz, to give a total rate to disk of about 3kHz.
2. Increase EDTM trigger rate to 10kHz, to ensure that after prescaling there are 10k-100k EDTM events per run.
3. Ensure the raster is on (2x2)

During scan

1. Monitor number of EDTM events: to ensure 10k-100k events/run
2. Try to get runs with minimum of beam trips: In particular, there might be a high number of trips due to the SHMS diffusor ion chambers at this small angle when running above 50uA. MCC can fix this by selectively changing the thresholds in the offending chambers. See here for more info. They should be aware of this.
3. Be wary of DC HV trips in SHMS: we are at a small angle, for some of the higher currents we will have to switch off the HV for the SHMS DCs
4. Use the highest current we can get: If MCC can't reach a current, we take data at the highest current that they can reach instead. This might mean we need to skip the some luminosity settings.

Sweep 1

0. Preparation

Rotate HMS to 12.50 degrees, everything else is unchanged.

1. P_HMS = -3.266 GeV/c (unchanged)
2. θ_HMS = 12.50 deg (NEW)
3. P_SHMS = 6.842 GeV/c (unchanged)
4. θ_SHMS = 6.49 deg (unchanged)

1 - 70uA LH₂

1. LH₂ target (unchanged)
2. Request 70uA; run at highest current available if we can't reach 70uA (likely)
3. If running at 70uA: switch OFF SHMS DCs: expecting ~1MHz SHMS singles rate which will trip the DCs
   1. Else: keep DCs ON and carefully monitor if running at lower current: ~55uA is the highest current we know we should be able to run without issues in this setting, but it is currently unknown at which exact current between 55uA-60uA the DCs start to trip.
4. Try to take a good 12min run with minimal trips

2 - 65uA C-1.5%

1. Change target to C-1.5%
2. Request 65uA; run at highest current available if we can't reach 65uA (likely)
3. Ensure SHMS DCs are ON and carefully monitor: rate should be bit lower
   1. If tripping is an issue, turn SHMS DCs OFF
4. Try to take a good 12min run with minimal trips

3 - 50uA C-1.5%

1. Keep C-1.5% target (unchanged)
2. Only if current for previous measurement was >50uA (common sense)
3. Ensure SHMS DCs are ON
4. Request 50uA
5. Try to take a good 12min run with minimal trips

4 - 50uA LH₂

1. Change target to LH₂
2. Only if current for previous measurements was >50uA (common sense)
3. Ensure SHMS DCs are ON
4. Request 50uA
5. Try to take a good 12min run with minimal trips

4b - ONLY IF SHMS DCs WERE OFF FOR STEP 1

1. Ensure LH₂ target (change if needed)
2. Ensure SHMS DCs are ON and carefully monitor
3. Request 55uA
4. Try to take a good 12min run with minimal trips

5 - 30uA measurements

1. Keep LH₂ target (unchanged)
   1. Try to take a good 12min run with minimal trips
2. Change target to Al Dummy
   1. Try to take a good 12min run with minimal trips
3. Change target to C-1.5%
   1. Try to take a good 12min run with minimal trips

6 - 15uA measurements

1. Request 15uA
2. Keep C-1-5% target (unchanged)
   1. Try to take a good 12min run with minimal trips
3. Change target to LH₂
   1. Try to take a good 12min run with minimal trips

7 - 5uA measurements

1. Request 5uA
2. Keep LH₂ target (unchanged)
   1. Try to take a good 12min run with minimal trips
3. Change target to C-1.5%
   1. Try to take a good 12min run with minimal trips

Sweep 2

0. Preparation

Rotate HMS and change both HMS and SHMS current, and move in LH₂ target:

1. P_HMS = -4.204 GeV/c (NEW, pass through MOL)
2. θ_HMS = 14.91 deg (NEW)
3. P_HMS = 6.053 GeV/c (NEW)
4. θ_HMS = 6.49 deg (unchanged)

1 - 70uA LH₂

1. LH₂ target (unchanged)
2. Request 70uA; run at highest current available if we can't reach 70uA (likely)
3. If running at 70uA: switch OFF SHMS DCs: expecting ~1MHz SHMS singles rate which will trip the DCs
   1. Else: keep DCs ON and carefully monitor if running at lower current: ~40uA is the highest current we know we should be able to run without issues in this setting, but it is currently unknown at which exact current between 40uA-50uA the DCs start to trip.
4. Try to take a good 12min run with minimal trips

2 - 65uA C-1.5%

1. Change target to C-1.5%
2. Request 65uA; run at highest current available if we can't reach 65uA (likely)
3. Decide what to do with DCs: should be able project from past runs what will happen
   1. If tripping is an issue, turn SHMS DCs OFF
4. Try to take a good 12min run with minimal trips

3 - 50uA C-1.5%

1. Keep C-1.5% target (unchanged)
2. Only if current for previous measurement was >50uA (common sense)
3. Decide what to do with DCs based on step 2
4. Request 50uA
5. Try to take a good 12min run with minimal trips

4 - 50uA LH₂

1. Change target to LH₂
2. Only if current for previous measurements was >50uA (common sense)
3. Ensure SHMS DCs are OFF
4. Request 50uA
5. Try to take a good 12min run with minimal trips

4b - ONLY IF SHMS DCs WERE OFF FOR STEP 1

1. Ensure LH₂ target (change if needed)
2. Ensure SHMS DCs are ON and carefully monitor
3. Request 45uA (might have to drop to 40uA, should now better by now)
4. Try to take a good 12min run with minimal trips

5 - 30uA measurements

1. Keep LH₂ target (unchanged)
   1. Try to take a good 12min run with minimal trips
2. Change target to Al Dummy
   1. Try to take a good 12min run with minimal trips
3. Change target to C-1.5%
   1. Try to take a good 12min run with minimal trips

6 - 15uA measurements

1. Request 15uA
2. Keep C-1-5% target (unchanged)
   1. Try to take a good 12min run with minimal trips
3. Change target to LH₂
   1. Try to take a good 12min run with minimal trips

7 - 5uA measurements

1. Request 5uA
2. Keep LH₂ target (unchanged)
   1. Try to take a good 12min run with minimal trips
3. Change target to C-1.5%
   1. Try to take a good 12min run with minimal trips

Aftermath

Return spectrometers to production settings. Rotate HMS and change both HMS and SHMS current, and move in LH₂ target:

1. P_HMS = -3.266 GeV/c (NEW)
2. θ_HMS = 23.00 deg (NEW)
3. P_HMS = 6.842 GeV/c (NEW, pass through MOL)
4. θ_HMS = 6.49 deg (unchanged)