Difference: MuDetUpdate (3 vs. 4)

Revision 42007-02-17 - PeterKammel

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META TOPICPARENT name="GeneralPK"
-- PeterKammel - 15 Feb 2007 * SET ALLOWTOPICCHANGE=Main.MuCapGroup
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Dangerous wall stop fraction

I did a quick study to determine the dangerous wall stop fraction. Assume that, for whatever reason,

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a fraction f_sup of incident muons stopping on the wall gets accepted. What is their effect on the lifetime?
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a fraction f_sup of incident muons gets accepted, irrespective of whether they have a good stop track in the TPC or not. What is their effect on the lifetime?
  For the study I used Tom's parametrization of the muSC/muPC1 - eSC 25 us PP time spectrum
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from his muon detector inefficiency study, add this spectrum scaled by f_sup to the nominal spectrum and fit with a 3 par fit. We should check how Tom's fit changes for impact cut constrained tracks. (Work directory: mucap/2007/studies/time/).
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from his muon detector inefficiency study. Define
  // electrons after entrance counter (no good TPC mu stop)
  TF1 *e_ngood= new TF1("e_ngood","[0]*exp(-[0]*x)*([1]+[2]*exp(-[3]*x)+[4]*exp(-[5]*x)+[6]*exp(-[7]*x))", tlow, tup);
  e_ngood->SetParameters(decay,0.19,0.07,0.0079,0.03,0.716,0.08,6.127);
  // electrons after entrance counter (good TPC mu stop)
  TF1 *e_good= new TF1("e_good","0.64*[0]*exp(-[0]*x)", tlow, tup);
  e_good->SetParameter(0,decay);
 
The total electron distribution is then generated as e(t)= e_ngood + acc + f_sup * ( e_ngood + e_good)

The detailed procedure is given in the ROOT script mudet.cpp, function create_n. The spectrum is scaled and randomized and the fitted with a 3 par fit.

  The input parameters were: repeat=100
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f_sup del_lambda (Hz) del_lambda (Hz)
(ppm) start=0.1 us start= 0.2 us
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10000 81 67
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10000 79 67
 
5000 40 34
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1000 7.8 +- 0.2 7.2 +- 0.2
500 4.3 +- 0.2 3.4 +- 0.2
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1000 7.7 +- 0.2 6.3 +- 0.2
500 4.2 +- 0.2 3.3 +- 0.2
100 0.8 +- 0.2 0.5 +- 0.2
  The fit residuals for f_sup=5E-3 are shown below.
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muSC TDIE R (kHz) deadtime(ms)   f_sup (ppm)
2.10E+01 21 1.00E-05 0.1 21.0
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In the estimate we have ignored that only 64% of the unseen muons can generate a good stop track in the TPC. In the TDIE estimate we have ignored the mu'-e' contribution (i.e. the unseen muon stops in the wall), which might double the effect. Both effects should be reduced by the impact parameter cut.
 

Snipped from Tom's Dec 2006 study

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META FILEATTACHMENT attr="" autoattached="1" comment="" date="1171688151" name="mudet.cpp" path="mudet.cpp" size="4633" user="Main.PeterKammel" version="1"
META FILEATTACHMENT attr="" autoattached="1" comment="" date="1171647795" name="c1.gif" path="c1.gif" size="26897" user="Main.PeterKammel" version="1"
 
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