Status Update on the Monte Carlo Simulation
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Transcript of Status Update on the Monte Carlo Simulation
Status Update on the Status Update on the Monte Carlo SimulationMonte Carlo Simulation
Vlasios VasileiouVlasios Vasileiou
April 20-21, 2007April 20-21, 2007
Milagro Collaboration MeetingMilagro Collaboration Meeting
ContentsContents
PE RescalingPE Rescaling Cosmic ray rateCosmic ray rate
PE ScalePE Scale
Problem:Problem: PE scalePE scale** in data not constant over in data not constant over
Milagro’s lifetimeMilagro’s lifetime Major reason Major reason Different calibrations Different calibrations
**PE scale relation between true number of pes in a hit with number of pes derived from the TOT method / MC
PE ScalePE Scale
MC PE scale was in best agreement MC PE scale was in best agreement with calibration v601. with calibration v601.
That calibration version was That calibration version was produced with the new bright laser produced with the new bright laser
Calibration v601 predicts numbers Calibration v601 predicts numbers of PEs closer to the true numbers of of PEs closer to the true numbers of PEs, than the other calibrations. PEs, than the other calibrations.
PE RescalingPE Rescaling
Reason for the change of the PE Reason for the change of the PE scalescale Imperfect filter-wheel calibrationImperfect filter-wheel calibration Change of laserChange of laser And many other reasons Andy and the And many other reasons Andy and the
people that were taking the calibrations people that were taking the calibrations knowknow
PE RescalingPE Rescaling
We are now rescaling everything : We are now rescaling everything : Rec data, raw data, MC data to Rec data, raw data, MC data to match the v501 calibrationsmatch the v501 calibrations
Rescaling enabled by defaultRescaling enabled by default Formula appliedFormula applied
PEsPEsrescaledrescaled = PEs = PEsoriginaloriginal (1+factor*log10(PEs (1+factor*log10(PEsoriginaloriginal)) For Rec data, factor depends on calibration version that For Rec data, factor depends on calibration version that
produced the dataproduced the data Andy calculated the appropriate factor needed to match Andy calculated the appropriate factor needed to match
the median of the mxpe distributions.the median of the mxpe distributions.
PE RescalingPE Rescaling
Plotted the percentiles of mxpe, X2, Plotted the percentiles of mxpe, X2, A4 from Rec data vs MJulianDate A4 from Rec data vs MJulianDate using a fluctuating ntop cut.using a fluctuating ntop cut.
The cut was selected to keep only The cut was selected to keep only the top 500Hz of datathe top 500Hz of data
PE RescalingPE Rescaling
PE RescalingPE Rescaling
Green 75% percentileRed 50% percentile (median)Black 25% percentile
Before After
Dashed lines come from the Rescaled MC using the same cut.
PE RescalingPE Rescaling
Green 75% percentileRed 50% percentile (median)Black 25% percentile
Before After
Dashed line comes from the Rescaled MC using the same cut.(it’s the wiggly one)
PE RescalingPE Rescaling
Before
After•A4 calculated with nfit_2layer•For the pre-outrigger era, A3 is plotted
PE RescalingPE Rescaling
mxpe, x2, A4 are now more stable mxpe, x2, A4 are now more stable between epochsbetween epochs
MC Cosmic Ray rates MC Cosmic Ray rates
As showed in previous collaboration As showed in previous collaboration meeting, the MC predicts a lower meeting, the MC predicts a lower cosmic ray rate than data vs ntop, cosmic ray rate than data vs ntop, ntop2, nfit cutsntop2, nfit cuts
g4sim 2.1, 5GeV-500TeV
0
0.2
0.4
0.6
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1.2
10 40 70 100 130 160 190
nfit cut
Rate
MC
/Rate
Data
Mirror cover
100% air under cover
50% air under cover
0% air under cover
Effects of air under coverEffects of air under coverg4sim 2.1, 5GeV-500TeV
0
0.2
0.4
0.6
0.8
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1.2
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1.6
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10 40 70 100 130 160 190
Ntop2 cut
Rate
MC
/Rate
Data
Mirror cover
100% air under cover
50% air under cover
0% air under cover
g4sim 2.1, 5GeV-500TeV
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0.5
1
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10 40 70 100 130 160 190
Ntop cut
Rate
MC
/Rate
Data
Mirror cover
100% air under cover
50% air under cover
0% air under cover
o Mirror cover = 100% diffuse reflections
o Reflected light doesn’t produce hits that participate in the fit
Cosmic ray rate vs nfit Cosmic ray rate vs nfit cutcut
For most of the nfit cut range, the For most of the nfit cut range, the MC predicts a cosmic ray rate of MC predicts a cosmic ray rate of about ~40-60% of the one from dataabout ~40-60% of the one from data
This could affect the flux calculation This could affect the flux calculation and possibly the energy estimation. and possibly the energy estimation.
Nfit cosmic ray ratesNfit cosmic ray rates
Out of ideas on what causes the Out of ideas on what causes the problemproblem Factors ruled outFactors ruled out
reflections from the cover, noise, time jitter, reflections from the cover, noise, time jitter, thrown energy range, corsika hadronic thrown energy range, corsika hadronic model, PMT corrections, using different model, PMT corrections, using different spectral indices & fluxes from different spectral indices & fluxes from different experimentsexperiments
Made hit and fit maps to see if there Made hit and fit maps to see if there is something funny with the MCis something funny with the MC
Fit Maps (no nfit cut)Fit Maps (no nfit cut)
Data run 6662Post-repair
MC 0.5 air under cover
Plots have same normalization and scale
Fit Maps (nfit>80)Fit Maps (nfit>80)
Data run 6662Post-repair
MC 0.5 air under cover
Plots have same normalization and scale
Cosmic ray rates vs nfit Cosmic ray rates vs nfit cutcut
Fit maps look similarFit maps look similar No features present in just one of the No features present in just one of the
mapsmaps Any ideas why the rates are smaller Any ideas why the rates are smaller
in the MC?in the MC? (or why the rates are higher in data?)(or why the rates are higher in data?) Used the same Epoch 5 analysis to Used the same Epoch 5 analysis to
calculate the ratescalculate the rates Cross-talk?Cross-talk?
Nfit_2layer vs timeNfit_2layer vs time