e /  final state study
0
Jaewon Park
University of Rochester
Vittorio Paolone
University of Pittsburgh
MINERvA Collaboration Meeting, Sep 13-15, 2007
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Overview
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Geant3-based minerva MC simulation
Study reconstructed track with nc-res sample. (Jaewon)
Study reconstructed track in ne CC events (Vittorio)
Track reconstruction efficiency, dE/dx, track length, and etc
Attemp to tune tracker
Study particle identification
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Tracker Filter requirements
 Definition
 View: X, U, or V
 HitPlane: Plane that has hits
 Minimum number of HitPlanes
 View that has largest number of hitPlanes >= 3 hitPlanes
 Sum of hitPlanes from the other two views >= 3 hitPlanes
 Minimum number of hit in a view
 Number of hits per view > 3
 Maximum cluster size
 Number of strips per plane in a cluster ≤ 4 (128)
single hit
cluster
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Digit hit – example event
uview
2
1
xview
p
vview
 Low energy, large angle gamma2 has a
few hits but it doesn’t look like that poo
r track.
 Tracker didn’t fit gamma2 because it di
dn’t meet the requirement
 Apply different loose requirement for s
hort track?
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Number of hitPlane for gamma
E(g)>120MeV
 Two gamma event sam
ple
 By looking raw digit h
its, simply check hitpla
ne distribution
 This is before applying
Kalman Filter
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Number of reconstructed gamma tracks
gamma1
gamma2
Before
 Modified tracker he
lped more on gamm
a1 but not much on
gamm2
 Gamm1,gamma2 is
order gammas by tr
ue energy scale.
E( 1 )  E( 2 )
gamma1
gamma2
After
 Before: original trac
ker
 After: modified trac
ker that allows gaps
in hit cluster
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Gamma track efficiency
Before
After allowing gaps in hit cluster
1
1
2
2
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Gamma track efficiency
2
1
With trackable normalization
Original events
Event satisfies hitPlanes>2
Reconstructed event
With trackable normalization
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Proton track efficiency
 NC-RES events
 Almost no difference
before and after allow
ing gaps in hit cluster.
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Pi0 mass reconstruction using gamma track
Before
After
 This is an optimal case: Two gamma tracks are reconstructed
 Not too much difference before and after
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Gamma track efficiency as function of angle
1
2
 It seems that tracker o
nly processes forward
tracks.
 Efficiency drops as th
eta angle increases.
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dE/dx (energy deposit sum)/(reco track length)
 NC-RES events
 Broad distribution
except muon.
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Average cluster size
p
Before
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p
After
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Average cluster size =
(total nStrips)/(number of coordinate)
 Before/After modificati
on on tracker to allow g
aps in hit cluster within
a plane
 I expected that average
cluster value correspond
s track fuzziness roughl
y when track angle to zaxis is small
 But most of track has al
most always 2 strips and
it can have more than 2
when it showers
ne flux (LE v19) files now accessible
in MC (Geant3 version)
Nu-e Energy (GeV)
Electron Reconstruction Efficiency
Event Sample: ne CC
Integrated over all energies: ~82%
Large cluster Size (# of strips used in layer) a go
od discriminator for electrons (and gammas)
Using ratio of cluster size from last part of track to first part of track as a cut one can easily
achieve an electron ID efficiency of ~50% and a rejection of hadrons ~1/200.
Last 3rd of track
Electrons
Protons
Pion
First 2/3’s of track
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Summary
Checked track reconstruction efficiency from
ne CC and NC-RES interaction.
Need to study further to tune tracker.
Cluster size(nStrips) seems good discriminatio
n (track vs. shower) for particle ID.