BPRS absolute gains using TPC MIPs & BTOW MIP cut, ver 1.6 , 2008 pp data

• INPUT:  fmsslow-triggered events, days 43-70, 525 runs, 16M events (see attachment 1)
  • BTOW peds & ped-status  from offline DB
• DATA CORRECTIONS (not avaliable using official STAR software)
  • discard stale events
  • private  BPRS peds(cap,softID) for every run,
  • private status table
  • event-by-event capID corruption detection and correction
  • use vertex with min{|Z|}, ignore PPV ranking, to compensate for PPV problem
  • BPRS swaps detected by Rory in 2007 data have been applied 
  • additional ~240 BPRS swaps detected & applied
  • BTOW ~50 swaps detected & applied
  • BTOW MIP position determine independently (offline DB gains not used)
• TRACKING:
  • select prim tracks with pr>0.35 GeV, dEdX in [1.5,3.3] keV, |eta|<1.3, zVertex <60 cm, last point on track Rxy>180cm
  • require track enters & exits a tower 1cm from the edge, except for etaBin=20 - only 0.5cm is required (did not helped)
• triple MIP coincidence, requires the following (restrictive) cuts:
  
  •  to see BPRS  MIP ADC :  TPC MIP track and in the same BTOW tower  ADC in  MIP peak +/- 1 sigma , but above 5 ADC 
  •  to see BTOW MIP ADC :  TPC MIP track and in the same BPRS tile   ADC in  MIP peak +/- 1 sigma , but above 3.5 ADC

Fig 1.   Example of typical BPRS & BTOW MIP peak determine in this analysis. 

MIP ADC gate (blue vertical lines) is defined (based on iteration 1.0) by the mean value of the gauss fit +/- 1 sigma of the gauss width, but not lower than ADC=3.5 (BPRS) or 5 (BTOW) and not higher than 2* mean ADC.

 FYI, the  nominal MIP ADC range for BTOW (ADC=4096 @ ET=60 GeV/c) is marked by magenta bar (bottom right).

• Attachment 6 contains 4800 plots  of BPRS & BTOW like this one below ( large 53MB !!)
• Numerical values of MIP peak position,width, yield  for all 4800 BPRS tiles are in attachment 4.

Fig 2.  ADC of MIP peak for 4800 BPRS tiles.

Top plot: mean, X-axis follows eta bin , first West then East. Y-axis follows  |eta| bin, 20 is at physical eta=+/- 1.0.Large white areas are due to bad BPRS MAPMT (4x4 or 2x8 channels), single white rectangles are due to bad BPRS tile or bad BTOW tower.

Middle plot: mean +/- error of mean, X-axis =soft ID. One would wish mean MIP value is above 15 ADC to place MIP cut comfortable above the pedestal (sig=1.5-1.8 ADC counts).

Bottom plot: width of MIP distribution. Shows the width of MIP shape is comparable to the mean and we want to put MIP cut well below the mean to not loose half of discrimination power.

Note, the large # 452 of not calibrated BPRS tiles does not mean that many are broken. There are 14 known bad PMTs and e 'halves' , total=15*16=240 (see attachment 2). There rest are due broken towers (required by MIP coincidence) and isolated broken fibers, FEE channels.

Fig 3. Example of PMT with fully working 16 channels.
Top left plot shows average MIP ADC from 16 pixels. Top middle: correlation between MIP peak ADC and raw slope - can be used for relative gain change in 2009. Top right shows BTOW average MIP response.
Middle: MIP spectra for 16 pixels.
Bottom: raw spectra fro the same 16 pixels.

300 plots like this  is in attachment 3.

Fig 4.  Top plot: average over 16 pixels MIP ADC  for 286 BPRS pmts.  X axis = PMB# [1-30] + pmt #[1-5]/10. Error bars represent RMS of distribution (not error of the mean).

Middle plot : ID of 14 not calibrated PMTs. For detailed location of broken PMTs see attachment 2,  the red computer-generated ovals on the top of 2007 Will's scribbles mark broken PMTs (blue ovals are repaired PMTs) found in this 2008 analysis.

Bottom plot shows # of pixels in given PMT  with reasonable MIP signal (used in the top figure).

• Numerical values of MIP peak per PMT are in attachment 5.

Fig 5.  ADC of MIP peak for 4800 BTOW tower. Top lot: mean, middle plot: mean +/- error of mean, bottom plot: width of MIP 

•  Numerical values of MIP peak position,width, yield  for all 4800  BTOW towers are in attachment 4.

Note, probably 1/2 of not calibrated BTOW towers are broken, the other half is due to bad BPRS tiles, required to work by this particular algo.

Koniec !!!