1 st look at dE / dx in GArSoft 19 Mar 2019 Leo Bellantoni New art - - PowerPoint PPT Presentation

1st look at dE/dx in GArSoft

19 Mar 2019 Leo Bellantoni

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New art Data Product

• .../ReconstructionDataProduct/TrackIoniz.*
• Now ../Reco/tpctrackfit2_module.cc, in the

KalmanFit function, will (forward pass only): for (TPCCluster=1 to <nTPCClusters) { add some dℓ to the track for the new cluster push dℓ and the ADC counts onto TrackIoniz }

• And in anatree_module.cc, call processIonizationData

(which is now in anautil.cxx)

• Well all that does is divide the ADC counts by dℓ and

take the average for the whole track

• Later, some calibration service should convert ADC

counts into pC

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• That went into git 3 weeks ago
• And a little bug fix last week
• I made a bunch ‘o MC
• 50k default GENIE events
• One file stuffed NaN into all my plots I got rid of it
• Match the MCParticle to a track if

PID ∈ {p±, !±, "±, e±}

• Honestly, the matching algorithm is crude –

just uses direction of initial momentum

• Use PTRUE not PRECO
• So far, no track quality cuts
• OK now some plots!

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GeV GeV GeV GeV

First look!

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Separation

• (!1 – !2)/(σ1 ⊕ σ2) actually not a great statistic for non-Gaussian

distributions

• low momentum p hit kinematic limit (e.g. at P = 150MeV, T =

12MeV, CDSA track length = 14cm and we are not getting those yet

• Then my 2nd rate track matching finds the wrong MCParticle

GeV

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Truncated means

• It is a well established technique to take the

mean of only the lower ionization readings to use dE/dx for PID

• OPAL: 882mº Ar, 98mº methane & 20mº, 4 bar. Truncated @ 700mº.
• ALEPH: 910mº Ar, 90mº methane at atmosphere. Truncated at 600mº.
• ALICE: 857mº Ne, 95 mº CO2, 48mº N2, at atmosphere. Truncated @ 700mº.
• PEP-4: 800mº Ar, 200mº methane, 8.5 atmospheres. Truncated at 650mº.
• I just tried cutting at 0.7 – obviously, some
• ptimization study possible

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GeV

Second look!

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Why the p do that?

• Scanning gives plausible reasons why there

might be abnormally low ionization: Missing hits (sector boundaries) Splinter tracks stole my ionization!

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Possible next steps

• Keep trying to figure out why the p do that (possible

event display upgrade)

• Select a cut and put it into the analysis
• Fix matching MCParticle ↔ charge deposits in GEANT ↔

hits ↔ tracks (gonna have to do this anyway)

• Build a calibration service (gonna have to do this

anyway)

• A better algorithm:
• figure out how to correct for the sector boundaries
• ptimize the 70%
• build a log-likelyhood discriminant based on distance from end

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Extra slides

• Level 1
• Level 2
• Level 3

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Extra slides

• Level 1
• Level 2
• Level 3

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Extra slides

• Level 1
• Level 2
• Level 3