Difference between revisions of "BCM calibration (d2n)"

Revision as of 12:11, 19 March 2010

BCM run list

Strategy

• Use special run to calibrate OL02 cavity against Faraday cup
• Calibrate EPICS bcm variable by calibrating BCMs against OL02
• Calibrate BB/LHRS scalers against OL02

Key for BcmLog files

Column headings for BCM log file (from Vince via Kalyan):

• Entry #
• BCM 1 voltage (upstream BCM)
• BCM 2 voltage (downstream BCM)
• Unser (not used)
• Faraday Cup (if extracted = 0)
• 0L02 (injector reading)
• 0R07 (not used)

Results for BCM calibration

Final results relating scaler rates (e.g. u1r) in Hz to Beam Current in uA:

The equations follow the form u1r = Slope*(Beam Current in uA) + Offset

Using scripts in Diana's ifarm account, /u/home/dseymour/d2n_analysis/bcm_calibration

From MakeBCMPlotHists, calibrating BCM1 & 2 to OLO2 for each current set point:

BCM1 = 0.020673 * OLO2 - 0.001692

• <math>\sigma_m = 0.000035</math>
• <math>\sigma_b = 0.000243</math>

BCM2 = 0.020990 * OLO2 - 0.001710

• <math>\sigma_m = 0.000037</math>
• <math>\sigma_b = 0.000276</math>

From MakeBCMPlotError, calibrating OLO2 to Faraday cup from linear fit to entire run (minus 12 outlier points). Data points given arbitrary error bars of 0.1 in x and y.

FARA = 0.9971 * OLO2 + 0.0171

• <math>\sigma_m = 0.0003</math>
• <math>\sigma_b = 0.0104</math>

Combining these equations gives the overall real current (in <math>\mu</math>A) from the BCM readings:

<math>\mu</math> = 48.24 * BCM1 + 0.0987

• <math>\sigma_m = 0.0829</math>
• <math>\sigma_b = 0.0157</math>

<math>\mu</math> = 47.51 * BCM2 + 0.0983

• <math>\sigma_m = 0.0849</math>
• <math>\sigma_b = 0.0167</math>

Results for Beam Charge calibration

yet to be done

Relevant HALOG entries

• Feb 17 BCM cal data:
  • HALOG: 0-25 uA run
  • HALOG: 30 uA run
  • HALOG: BCM strip chart during calibration

• Halog 263768 02/27/09 23:15 Kalyan BCM calibration : 0L02 vs BCM1 and BCM2
  • Halog 263890 02/28/09 16:52 Kalyan BCM calibration : OLO2 vs Left HRS scaler
  • Halog 264176 03/02/09 11:18 Kalyan Re: BCM Calibration: BCM1 and 2 vs 0L02 -- new plot

Useful Documents

• Explanatory page from PVDIS experiment
• Vince Sulkosky's tech note
• Mark Jones's tech note: Media:Jones_bcm.pdf‎