d. jason koskinen fnal collaboration mtg. 10/2005 1 near detector efficiency

D. Jason Koskinen FNAL Collaboration mtg. 10/2005 1

Near Detector Efficiency


Rehash

Examining the efficiency of the Near Detector to record muon hitsEfficiency defined as #hit planes expected/#hit planes seenR1.16 was used initiallyCuts– Pitt track quality(chi2/ndof<20,|beginU -beginV|<6,

pass tracker fit)– Through going spill muon– Fiducial: 0.3m<U<1.8 and -1.8<V<-0.3 for vertex and

track end-2 planes


Track Efficiency– How many planes hit for individual tracks

Plane Efficiency– record how many tracks traverse plane and how many

hits are recorded

X X X X X X X X X X X XVertex End Plane


Initial Results

Calorimeter Tracks (120 planes)– Partially Instrumented (PI)

was .8883 +/- .0136– Fully Instrumented (FI)

was .8783 +/- .0140

Inefficiency stems from – Tracking– Poisson(PMT)-

Landau(Scintillator) nature of light

– Other Stuff?


Quick Check

Study of the Far Detector put the tracking efficiency at ~.95 (John Marshall)

– Extracting the tracking efficiency from overall efficiency yields the inefficiency due to light

● 1-.88/.95=.074

Is the ~7% inefficiency that is not track related solely from light or is it systematic of another problem?– Examine ADC per plane to get idea of light

contribution


Top plot shows summed ADC for all spill muon hits (w/o cuts) in May– Landau fit for comparison

Bottom shows similar with a 7.4% increase in low ADC counts– Simulates 0% light

inefficiencyThe ~7.4% is not totally light dominated


Monte Carlo Comparison

R1.16 High Energy Monte Carlo– PI .9446 +/- .0172– FI .9485 +/- .0140

MC is 6-7% higher using same method/codeDiscrepancy is big


MC/Data Discrepancy causes

Low level ADC hits in MC, which are not seen in dataMore MC tracks staying in analysis region of detector – inside volume containing both FI and PI planes

Data efficiency being 'pulled' down handful of single tracks with low efficiencyReconstruction not finding hits in data that are part of track


Both MC (top) and Data(bottom) track efficiencies are 'smooth'No peak at low efficiency values


Data(red) MC (blue)MC and Data are similar in ADC level

<2% of events fall outside fidvery similar to MC


Tracking

Removed possible tracking issues– Used all hits in event, regardless of (U,V) position

Efficiency increase of ~1% in both MC and Data


Inefficiency not caused by:

Low level hits– MC and Data have similar ADC distribution

More Data tracks move out of fiducial region– MC and Data have similar hit distribution

Handful of tracks with low efficiency in data– No spike in Data track efficiency plots at low

efficiencyThe only bit left is that the reconstruction is not finding or allocating hits to the track


More possible causes

'Dead' bits of Near Detector– Strips or planes that may not respond as effectively as

expectedAlignment issues – Are muon tracks in Data sneaking through gaps

Actual hits are not being included in event


Uniform distribution for both methods

Two methods of establishing missing hit position– Neighbour – interpolate missed hit position from adjacent

hits– U/V – use hit positions in next similar plane

● ex. Missed hit is a U plane, two nearest hit U plane positions are used


GapsIdentified by missing hits near strip edges– Hits congregate near edge more in MC than data– Tracks not 'slipping' through gaps

R1.16 Data R1.16 MC


R1.18R1.18 Data matches R1.16 MC, but not Data

R1.16 R1.18 MC

Track hits

All hits


2005-06 R1.16 2005-06 R1.18 MCTrk_efficiency PI 0.8794 0.9457 0.9465All_efficiency PI 0.8867 0.9481 0.9492Trk_efficiency FI 0.8863 0.9370 0.9408All_efficiency FI 0.8726 0.9387 0.9431

Same set of data (06/2005) with different reconstructions (R1.16, R1.18) have different efficenciesSuggests that hits are not being included in events in R1.16, but are in R1.18


Look at same event in R1.16 and R1.18 when efficiencies differ– R1.16 has 69% track efficiency, R1.18 has 94%

R1.16

R1.16

R1.18

R1.18


End

Finished– The culprit of the Near Detector efficiency issue is

hits not being included in event● slicer?

– Old code sucks, new code goodOutstanding– Missing hit location between MC and Data

● Missing hit location is similar for R1.16 and R1.18 Data, but does not match MC

● I'm not doing this

d. jason koskinen fnal collaboration mtg. 10/2005 1 near detector efficiency

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