====== Beamtime Jan 2018 ======

  * elog entries: https://him-elog-01.him.uni-mainz.de/Beamtime+January+2018/page1

==== Nitrogen ====

Please check the nitrogen pressure twice a day! 
Approximately 50 bar per day are used.

The bottles are placed in the detector lab in the A1 ground floor.

^ Pres /bar  ^ date          ^
| 105        | 31.01. 15:55  |
| 75         | 1.2. 10:00    |
| 50         | 2.2. 00:01    |
| 48         | 2.2. 04:00    |
| 175        | 4.6. 17:10    |
| 150        | 5.6. 13:00    |
| 100        | 6.6. 20:00    |
| 100        | 6.6. 22:15    |
| 85         | 7.6. 05:10    |
| 65         | 7.6. 15:45    |
| 55         | 7.6.  20:00   |
| 40         | 8.6.  01:20   |
| 35         | 8.6.  04:05   |
| 29         | 8.6.  06:45   |
| 20         | 8.6. 10:45    |
| new        | bottle        |
| 210        | 8.6. 13:45    |
==== General Overview ====

Beam test 31/1 – 5/2/2018:

===1 Get beam===

  - start with smallest current (1 nA)
  - if event rate too high: install picoamperemeter

===2 Preparation with C, 1.5 GeV, smallest angle===

For each setting:

  * measure rates
  * take spectrum (look at gamma and e spectra)

Steps:

  - set up coincidence between EMC and scintillator
  - increase beam current up to 100 nA in various steps -> find appropriate current value
  - change thresholds
  - move prototype with the xy table
  - set up coincidence with spectrometer A

===3 HV and energy calibration (plastic target)===

  - recognise one or more energy peaks
    * elastic on C (nucleus)
    * elastic on H
    * inelastic on H in coinc. with spec. A
  - adjust HV
  - change angle or spec. A settings for changing the peak energy


===4 Total rate and global spectrum with Ta===

  - vary beam current -> find appropriate value
  - threshold scan at the smallest angle
  - vary scattering angles

===5 Identify pi0 events (measuring gammas)===

  - use second scintillator at different angles for electrons
  - set up triple coincidence
  - change spec. A polarity to measure electrons
  - set up coincidence with spec. A
  - measure gamma spectrum changing angle and spectrometer settings (measure end-point of the gamma spectrum)
  - try different targets C,CH2,Ta

===6 Measurements with 855 MeV===

  - change beam energy (until Friday noon!)
  - increase beam current to appropriate value
  - repeat measurements for energy calibration
  - repeat measurements for total rate
  - repeat measurements for pi0 event identification