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Cross-Calibration of FDs

Cross-Calibration of FDs. Sean R. Stratton TA-All Meeting – June 2010. Motivation. We’re still trying to understand the relative energy scale differences between our FDs. The UVLED was used to cross-calibrate all three FD sites.

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Cross-Calibration of FDs

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  1. Cross-Calibration of FDs Sean R. Stratton TA-All Meeting – June 2010

  2. Motivation • We’re still trying to understand the relative energy scale differences between our FDs. • The UVLED was used to cross-calibrate all three FD sites. • Although RXF tests have been done in the past, we needed a longer, more thorough test to be done.

  3. BRM/LR Calibration Method • Get absolute calibration for selected tubes. • CRAYS. • Gain-match remaining PMTs by adjusting individual HV. • Correct tube gains in each camera according to: • Camera temperature. • HV supply. • Relative gain from XF data. • Gains relevant for 1 hour periods.

  4. BRM/LR Calibration Method • Get absolute calibration for selected tubes. • CRAYS. • Gain-match remaining PMTs by adjusting individual HV. • Correct tube gains in each camera according to: • Camera temperature. • HV supply. • Relative gain of center PMT (0x77). • Gains relevant for 1 hour periods. Hardware Level

  5. BRM/LR Calibration Method • Get absolute calibration for selected tubes. • CRAYS. • Gain-match remaining PMTs by adjusting individual HV. • Correct tube gains in each camera according to: • Camera temperature. • HV supply. • Relative gain of center PMT (0x77). • Gains relevant for 1 hour periods. Software Level

  6. The Calibration Constants

  7. Case Study: BRM 20090225 • Clear CLF run night • Lots of data (~10 hr.)

  8. BRM G0 as of Feb. 08

  9. BRM Gtotal for 20090225

  10. G0 = 0.5087 T0 = 24.55

  11. Camera 08

  12. When/Why was HV Changed? Camera 07

  13. Camera 10

  14. Camera 05 Camera 10 Camera 07

  15. 4 5

  16. 4 5

  17. 6 7

  18. 8 6 7

  19. 10 11

  20. 10 11

  21. 22 Sep 2008 25 Feb 2009

  22. Camera 05

  23. Question 1 Are the built-in XF used as an absolute light source or is it used to check uniformity and relative gains? In other words, do we know or care exactly how many photons are produced by each XF per flash?

  24. Question 2 It is our understanding that the HV supplied to each tube is adjusted to match the output signal of the absolutely calibrated tubes (0x77, 0x33, & sometimes 0xB3), using covered mirrors and the built-in Xenon flasher apparatus. How is this done? In software? Low-level analysis?

  25. Question 3 If each tube’s HV is adjusted to gain-match the absolutely calibrated PMT’s, then why would we need to adjust the HV of an absolutely calibrated PMT (from CRAYS)?

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