November 6, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20041 Particle ID, energy...

November 6, 2004 Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 2004 1

Particle ID, energy resolution, neutrino flavor tagging, efficiencies, backgrounds, and the kitchen

sink

Carl Bromberg Michigan State University

& Fermilab (2004)

What have we learned from MC and event display scanning?


MC interactions• A.P. generated

– Electromagnetic showers due to an electron, pi-zero, or

– (NeuGen) -interactions in LAr:• Charged Current • Neutral Current • with energy spectrum of the off-axis neutrino beam

• GEANT simulation of energy deposited by produced particles as they propagate (or decay) in LAr.

• Record “drift” distance and charge (within 5 mm of drift of a track) on 5 mm pitch wire planes.

• Instructions on FLARE website to DISPLAY -events www-off-axis.fnal.gov/flare/detector_simulation.htm

lN→ l + hadrons( )

lN→ ν l + hadrons( )


Sample e -> e + hadrons

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.








What NC rejection is needed?

• Most (80%) NC events have observed energies below 1.5 GeV or above 3 GeV

• Near 2 GeV, rejecting 95% of the NC events reduces this background to half the beam e contamination.


NC events (E observed, 1.5 - 3.5 GeV)














Scanning rules• Develop scanning rules to classify events as CC

e – Select events with observed energy between 1.5 to 3.5

GeV– Where is the primary vertex?

• back track to common point• beware of backward moving tracks• vertex obscuration, can we afford to reject?

– How many clear tracks leave the vertex and travel for at least 2 cm with a minimum ionizing signature

– Do any of these tracks develop into electromagnetic shower?

• Train scanners to apply scanning rules• Evaluate CC efficiency and NC rejection


Rejection of coherent 0

• Feared background:

coherent production• Use MC generated

“events” -- EM showers. • Start at earliest hit and

add energy depositions for 2 cm of track

• Cut around 1 mip (2 MeV/cm)– 82% efficient for e– 91% rejection of 0

– 93% rejection of

electron showers

Energy deposited in first 2 cm

0 -> 2 - showers

- showers

N→ π 0N


Outlook

• First look is very encouraging• If full scanning tests confirm

– need to code and tune the rules– show automatic scanning gives the

same results on new events• May convince skeptics of advantages

offered by LAr technology

November 6, 2004Carl Bromberg, FNAL LAr Exp. Workshop Nov. 4-6, 20041 Particle ID, energy...

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