Proton Calorimetry/Meetings/2017/08/23

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Minutes for UCL Proton Calorimetry Meeting, 23rd August 2017 (D17, Physics & Astronomy, UCL)

Present

Simon Jolly, Laurent Kelleter, Anastasia Basharina-Freshville

ABF:

  • Will start writing paper today.
  • Will clone PBT publication git repository from CVS.

LK:

  • Working on transfer report.
  • Will generate plot to show comparison for layered calorimeter between measured light output, reconstructed quenched Bragg curve and Bortfeld formula.

Planning for Birmingham

  • Trip to Birmingham on 23rd (today) was cancelled due to cyclotron issues.
  • Rescheduled for Friday 25th.
  • Need to make measurements with each scintillator sheet at front of scintillator stack to calibrate light output. We will define the light level of a sheet when it sits first in the stack as its calibration level output:
    1. Arrange scintillator sheets with 3 mm sheets at the front and 4 mm sheets in the middle; remove 10  sheets.
    2. Make a measurement with the sheets in this configuration.
    3. For each group of 3 sheets, take the front sheet out, move the 2nd and 3rd sheets forward and insert the first sheet at the back of the group. So the 2 groups of scintillators that are grouped {(1,2,3),(1,2,3)} are now grouped {(2,3,1),(2,3,1)}.
    4. Retake the measurement.
    5. Reorder the sheets as above once again, so that the 2 groups of scintillators are grouped {(3,1,2),(3,1,2)}.
    6. Take a 3rd measurement. You now have calibration levels for the 3 3 mm sheets, as well as light output Bragg curves with the optimum configuration (but no calibration levels for the 3 thick sheets).
    7. Rotate the scintillator stack 180 degrees so that the 4 mm sheets are now facing the beam.
    8. Repeat the sequence of taking a measurement and reordering the stack as above. You now have calibration levels for the 3 remaining sheets.
    9. Remove the thin sheets and place only the two thick sheets in the beam. Take two measurements with the sheets in alternate positions.
    10. Make measurements with the thin scintillator sheets facing the beam and moving the beam vertically and horizontally across the sheet to determine the variation in light output.
    11. Take several measurements with the beam in the same position and the sheets in the same location to characterise the change in light output due to radiation damage.
  • As discussed, the sensors will be aligned so that each sensor measures every sheet i.e. the join between sensors runs collinear with the beam direction. That provides a comparison between sensors and makes sure we don't get any difference in output between sensors that may affect the calibration.
  • Check the variation in light out across the scintillator sheet: it will be interesting to see what the difference is in measured light output between the centre and the edges and also if this fall-off is the same between sheets.
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