muons at caldet introduction

Muons at CalDetIntroduction

Track Finder PackageADC Corrections Drift Points Path Length Attenuation

Strip-to-Strip CalibrationScintillator Response with Temperature Time

Off Beam Energy Muons Alignment

Track Finder

Track each plane orientation separately

Follow track through each plane of detector by looking for hit strips within a user specified range

No more than 2 hits in any plane on the track

Event Display - Muon

Event Display - Pion

Event Display - Electron

ADC CorrectionsDrift Points

Drift points taken every 20 mins during runsCorrect all ADC values back to a reference point for each strip end to remove gain driftCorrection hidden from end user – procedure fully “framework-ized” at CalDet

Path Length Correction

Average path length for finite strip width:

ds = (ds/dz) . [4.05/(4.05 + dT/dz)]

Calculate path length from local track angles

Attenuation – Uncorrected ADC Versus Position along Strip

Attenuation – Characterization (Ryan Nichol)

Attenuation – Corrected ADC Versus Position along Strip

Attenuation – Corrected ADC Versus Position along Strip

Strip-to-Strip Calibration

Currently only apply Drift and Path Length Corrections to Track Hits (Attenuation to come…)Histogram Double Ended Hits and Find 90% Truncated Means per Strip EndWrite Strip-to-Strip Normalisation Factors to Database: Users can obtain charge in Normalised “CalDet” ADC unitsTypically enough muons to update strip-to-strip corrections each run (to remove temperature variations in strip light output)CandDigit::Reco slow - not feasible so far

Results using Cosmic Muons

Angular Distributions of non-beam runs clearly show contribution from PS muons20o Vertical Angle Cut Cosmic muon sample

Results using Cosmic Muons

Light output in NPEs at 23oC:Green: 3.6 pes

Clear: 4.5 pes

Light output variations:Green: 13.0%

Clear: 16.4%

Aside: Gains

GainsGreen: 75 ADCs

Clear: 75 ADCs

WidthGreen: 10%

Clear: 10%

Calibration Check: Muons

Apply Strip-to-Strip Calibration to All Muon Hits Expect RMS/Mean to decrease by: [(Gain Spread)2 + (Light Output Spread)2]0.5 ~ 25% Green

25% Clear

Calibration Check: Electrons

Apply Strip-to-Strip Calibration to All Electron HitsSummed Corrected ADC Dist for electron events narrows slightly <1%Corrections “washed out” by summing

Scintillator Strip ResponseShort Term Variations

Now have Temperature probe at CalDet! (UTexas)

Measure Fractional Changes in Light Output with Time

Compare with Shifts expected due to Temperature

Scintillator Strip ResponseLong Term Variations

Using Temperature Measurements from HARP experiment (also in PS East Hall) can compare light output from 6 month old cosmic runs with recent runsLight output appears to be stable on this timescale

Off Beam Energy Muons

Looking at Track Range for 2 GeV run:Expect a peak at plane ~55 …Instead seem to get a spread of energies + many higher energy muonsNot useful for understanding MC/T11 Range differences

Off Beam Energy Muons

Look at distribution of vertical strip hit in first plane vs horizonal angle for through-going muonsCan see that…

Use high energy, straight muons to measure plane alignmentFix hit in first plane of detector (for each orientation),fit straight line to rest of track alignment wrt first planePlot (expected hit strip – actual hit strip) for each plane:

Alignment

Alignment

Offsets w.r.t. first plane=================Even:Mean ~ 0.1cmsRMS ~ 0.2 cms

Odd:Mean ~ -0.74 cmsRMS ~ 0.4 cms

Summary & Future

CalDet Calibration running within FrameworkScintillator Light Output Variations UnderstoodT7 running unable to shed light on MC/T11 Range differencesAdd Attenuation CorrectionsCompare Alignment Measurements with Offline Package – use misalignment info during track reconstruction/path length & attenuation corrections