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Message ID: 64     Entry time: Thu Mar 19 15:09:29 2020
Author: Jan 
Category: General 
Subject: starting off with DSSSD 
Year:  
here is my short guide how to start with the measurement as soon as we have a beam available.

0. ESR timing in DAQ (maybe Uwe can also assist here)
    - when the cycle is running already, even for tuning, you can try to make the cabling for ESR timing (jet ON/OFF)
    - replace the gate generator signals by the ESR timing signals in the Messhütte and check UDP reader (E127_rates)
    - the settings for ESR timing (event & machine) depend on the cycle, talk to Sergey or so, its the same settings as for the target in HKR
    - with the current cycle this would be: ON-{machine 11, event 55}, OFF-{machine 13, event 55}
    - the event for end of this process is alway 55
    - if it works all tpat rates should be switching from upper to lower panel with the ESR cycle in the rate monitor (as they do now with the gate generator)

Once the tuning is finished:

1. optimize target ON/measurement time
    - switch target to event and use the same machines/events as above
    - check number of ions in ESR at ON and OFF and lifetime of beam
    - we should measure for a drop of a factor of 3-4 roughly i would say
    - e.g. start with 2e5 and stop with 5e4
   - if we start with more, we can measure longer

1. without target,  put in Si detector (GE01DD4AS in device controle) to max-in position
    - see if it disturbs the ESR cycle (discuss optimization with ESR guys if necessary)
    - we should also check vacuum in ring (i think this can be done remotely, ask Markus, Sergey or so)

2. make Si settings with beam (call me i can do things remotely)
    - voltage to 60 volts, use E127_epics (i would expect the current at ~1uA, if no light source is close by)
    - check picoscope for signals during entire cycle
    - picoscope: (ch1: E_x ,ch2: Ex, ch4: gate)
    - select central strip in y and 1st or 2nd x-strip as monitor output with epics (E127_epics > MSCF Si 1 & 2)
    - if you don't get any at all, switch on target in measurement cycle (or permantely)
    - still no nice signals? -> polarity is probably wrong, we need to switch MSCF of X and Y
    - during our measurement period, the signals should be well below 10V (goal for reaction ions ~6V)
    - adjust shaping time, gain, pole zero, threshold (epics) and Si-gate delay and length (e127.trlo) until you get nice histos
    - if you see large rates at injection or decelleration, we should try to shield detector with the scraper
    - put it as close as possible without disturbing the cycle, i.e. loosing more beam than without scraper
    - we can also move it by event (e.g. move in or out on start or end of machines 4,6,11,12,13) depending on when it disturbs

3. find beam position at detector
    - stop the cycle in SC 11
    - try to scrape it away by moving the detector our with small steps
    - you will need several injections, because if the short liftime, can get tedious
    - follow instructions and numbers here: https://elog.gsi.de/esr/E127/37

4. last things
    - ignore BaF for now
    - check that x-rays are working, spectra okay? resolution?
    - check rates during ON (x-rays: some 100 Hz each, Si: low, probably below 100Hz) and OFF (below 100Hz for all but BaF)
    - check deadtime, do we need downscaling for any detector? (i would not expect this, BaF is downscaled already, don't worry)

5. first runs
     - measure with and without scraper to confirm that Rutherford is under controle
     - how long? > depends on the statistics
     - try to see a clean effect of scraping, e.g. by the Si-plot E_ion vs x_position (Laszlo)
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