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T8 proton beam data & measurements - meeting 1

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# INTRODUCTION (FRa / KB)

1) Data for XSEC023 exist in the logging with "nominal" calibration factor but were not used for the analysis so far;

2) The intensity spread seems to be reduced after 9/11 and the change in the BTRAIN settings (that could have affected the start time of the extraction) but this needs to be verified in 2022 because of low statistics in 2021;

3) PR.BCT plot has 1 point every 1ms: same sudden jumps seen also at the SPS, this could be due some Power Converter (PC) instabilities, but need to be further investigated:

  1. how may spills in 2021 are affected by these jumps: can we make some statistics ?
  2. would it be possible to relate the intensity data with the PC current measurements ?

4) Continue to investigate the response of the XSEC070: waiting for data from Luana (SY-BI):

  1. is there any saturation of the XSEC signal during the jumps ?
  2. what is the effect of the second small peak in the calculation of the integral of the XSEC signal ?

4) Open the XSEC023 (F61) to understand how it is made and why it is overresponding - DONE:

  1. window was found broken and absence of vacuum conditioning (this might be the cause of the overresponse)
  2. foils stacks are of Al not Ti (same as the XION) and they are all "plain" foils;
  3. decided to refurbish the device and remove the I-LOSS foils stack: cleaning, sealing testing, etc. to be done before the end of the YETS;
  4. the "powder" removed during the opening will be brought to analysis lab.

# BEAM INSTRUMENTATION (FRo/MD/AG)

1) operation in LINEAR mode ("standard"): 1sample/20ms as it is done for the NA to sample a spill of several seconds but not good for all EA beam conditions;

2) operation in INTEGRATION mode: 1sample/10us and not possible to apply this calibration factor to LINEAR mode.

We have two solutions:

  1. Intercalibrate the beam intensity with independent systems and aim to have a defined ration between the LINEAR mode (operation) and the INTEGRATION mode (calibration with FE beams);
  2. split the XSEC signal and use the INTEGRATION mode for all beams (this implies also to change a Capacitor in the hardware): for this solution action is needed (to be decided); 

3) For the commissioning 2022 it is planned to measure the XSEC analog signal and compare it with the digital one recorded by the electronics;

4) XSEC signals sent to IRRAD:

  1. test of XSEC094 seems ok, the 2 outliers can be checked by Ana;
  2. the new solution of sending the pulse from the BTV card now works for all firmware versions (independent from this) and can be used from 2022: we just have to switch the cabling in APRON also for XSEC070

# TRANSFER LINE MEASUREMENTS (EJ):

1) measurements performed with "kick-response" methodology: data taken by measuring the movement of the beam on BTV (using the glow on the screen) and then treating the data with cook's algorithm; 

2) Some discrepancy to be understood probably due to wrong polarity of magnet currents (sometimes in FESA classes) sometimes in the instrumentation. CHARM BTV is OK, MWPC polarity needs to be corrected;

3) Next step is (1) to complete the understanding of these results (use MAD-X model to best fit the data) and (2) the aim is to use this as the basis for an optimizer. Optimum for IRRAD would be a "parallel optics" focusing the beam upstream the IRRAD area. Current beam shape upstream IRRAD could be due to the beam scraping certain beam elements.

4) Other study to plan is about the beam envelope: with an octupole scan we can see the variation of the beam envelope. This has to be done with low intensity to avoid the BTV to saturate (FRo said that BTV were consolidated not long ago but are not equipped with optical filters to prevent saturation. The camera are RadHard but BTVs are not really accurate for measure the beam size). For this work it would be useful to provide OP with IRRAD BPM and East Area BTV's in YASP.

5) It would be useful to add more instrumentation especially for ions, taking also into account that for ion tests there will be only one position used (not all along the beamline as in IRRAD):

  1. after the meeting a discussion has been started to add a scintillator in CHARM
  2. check the response of the MWPC and see if possible to tune its gain

6) Further measurements can be started with MD work on PS-DUMP (not interfering with T8 operation). We have agreed that when needed/possible (to be discussed weekly), on Wednesday OP can have time to work propagating the beam down T8 when the access ends and before we restart experiments in both IRRAD and CHARM.

7) Same measurements to be repeated for ions. Power converters are not PPM so it is not possible to save different setting for different users (e.g. not possible to work in parallel).

# DIODE & OPTOCUPLER EXPERIMENTS (NE, PA, RF):

1) Diode:

  1. Proton beam: only SE data at certain distance from the beam center. Diode current saturates at 55uA. Heavy ions: both SE and FE beam data recorded;
  2. It seems that the measured longitudinal profile has the same shape as the one from the BPM but not the same time width. Moreover, the beam center, as measured by the diode, seems not to be the one assumed and set on the X-axis of IRRAD7: provide details of the longitudinal profile as measured by BPM2 and cross-check the position of the beam on IRRAD7.

2) The presented frequency analysis shows peaks as predicted by simulations as well as noise spectrum differences to be understood. What is observed here are high-frequency effects (~>MHz), potentially interesting for SEE testing but probably nor related (or causing) the instabilities observed in T8 during 2021;

3) SET measurements done with Opto-couplers show the same beam intensity shape (in time) if the comparison with the BPM data is done with the same computation of the derivative. The data for ions seems to be in better agreement (maybe because of the smaller bin size ?): try to compare SET data with raw BPM could be more accurate ?

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