ICARUS T600: preliminary analysis of cosmic ray induced interactions with and production

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ICARUS Collaboration Meeting LNGS, 18/07/06
p0 detection and reconstruction with the ICARUS
T600 LAr TPC final results

• G. Battistoni, R. Brunetti, K. Cieslik, A.
  Dabrowska, R. Dolfini,
• Gigli Berzolari, J. Holeczek, J. Kisiel, J.
  Lagoda, M. Markiewicz,
• F. Mauri, A. Menegolli, P. Mijakowski, T.
  Palczewski, A. Piazzoli,
• A. Rappoldi, G.L. Raselli, E. Rondio, J.
  Stepaniak, M. Szarska, A. Zalewska

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Contents

• Motivations
• Search for hadronic interactions with neutral
  meson production scanning and reconstruction
  methods
• Final results from ICARUS T300 data
• Simulations of neutrino interactions with p0
  production
• E.m. shower energy resolution
• Conclusions

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Motivations

• Study the capability of T600 detector to
  identify neutral pions
• and reconstruct their mass through real event
  analysis (surface
• Pavia run)
• Study the performance of T600 detector in
  reconstructing
• electromagnetic shower of several hundreds
  MeV (coming from
• the photons of p0 decay)

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Scanning rules for hadronic events with neutral
meson production a reminder

• An interaction with a clear main vertex in
  three views is searched
• The main vertex is defined by two charged
  tracks (at least) converging
• to the same point
• Two photons (at least) must be present,
  generating clear e.m. showers
• pointing to the main vertex in Collection
  view and in one of the two
• Induction views

Drift time coordinate
Wire coordinate (3mm pitch)
The result of the scanning was a pre-selection
of 570 neutral meson candidates
All runs from ETH list including hadronic
interactions have been scanned, for a total of
7500 images analyzed
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Reconstruction tools

• Identification of all hits belonging to a
  shower
• Hit finding and reconstruction in Collection
  View
• Deposited energy reconstruction
• g direction reconstruction through association
  of
• Collection and Induction views
• Evaluation of invariant mass of gg system

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Measurement of (g,g) systems

• For the evaluation of the invariant mass Mgg of
  (g,g) systems are needed
• The two shower energies, E1 and E2
• The angle q12 between the two showers

The angle q12 is computed from the coordinate of
the main vertex of the interaction and from the
starting points of the two showers
C calibration factor converting from ADC
to MeV (after MC simulations) Ak k-th hit area
in ADC counts e(tk-t0/te) correction for drift
electron finite life time te
1kQ(dE/dx) electron-ion recombination
factor (Birks law)
Shower energy is given by
Hits inside the green polygonal line only are
selected for energy reconstruction
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ICARUS T300 data analysis
The four labs involved in the analysis (Katowice,
Krakow, Pavia, Warsaw) have collected 570
events of hadronic interactions with production
of at least two e.m. showers.
The number of such events that it was possible to
measure twice independently with the newest
version of the software is 250.
Criteria of agreement between two different
measurements of the same event were studied and
applied to the data.
The final sample of good events is built after
the averaging of main vertex and shower
coordinates and shower energies of events who
survived the agreement criteria.
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Agreement criterium 1 main vertex position
Dx - 0.003 cm s 0.367 cm
Dy - 0.038 cm s 0.395 cm
Dz - 0.015 cm s 0.252 cm
If differences between main vertex coordinates
independently measured are within the average
difference 5 s, then main vertexes are
considered to be in agreement, otherwise the
event is rejected.
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Agreement criterium 2 shower starting points
Dx - 0.085 cm s 0.567 cm
Dy - 0.035 cm s 0.389 cm
Dz - 0.018 cm s 0.380 cm
If differences between shower vertex coordinates
independently measured are within the average
difference 5 s, then shower vertexes are
considered to be in agreement, otherwise the
event is rejected.
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LAr radiation length evaluation
After the agreement on coordinates, the
distribution of the distances of the shower
starting point from the main vertex of the
hadronic interaction has been built
X0 (17.5 1.2) cm

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X-distribution of hadronic interaction verteces
The distribution of hadronic vertexes along X
(vertical) coordinate is related to the LAr
interaction length
141 events
Top of T300
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Agreement criterium 3 shower energy
If the relative difference is larger than 0.5
(absolute value) the event is rejected
DE 0.2 MeV s 3.4 MeV
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More event rejection criteria
After the agreement criteria rejections, two
more cuts were applied to get the final database

• Rejection of events belonging to the Bad Sector
• of the Right Chamber of T300 it is required
  that
• at least the first 90 cm ( 6 X0) of a shower
  are
• outside the bad sector
• 2. Rejection of events in which single charged
  tracks
• crossed at least one of the e.m. showers.

Fiducial volume cuts are going to be included it
will be required that at least the first 90 cm
( 6 X0) of a shower are fully visible in the
event selected view
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gg invariant mass and p0 total energy two shower
events
Ea 400 MeV

• two shower events
• sm/m lt 15
• no charged tracks crossing.

mgg 128.0 4.0 MeV/c2
RMS 24.4 MeV/c2
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gg invariant mass and p0 total energy add
multi-shower events
Ea 370 MeV

• two multi-shower events
• sm/m lt 15
• no charged tracks crossing
• proper g pair disentangled from
• c square analysis.

mgg 125.7 3.7 MeV/c2
RMS 25.7 MeV/c2
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Reconstruction method has been validated through
FLUKA simulation of events with p0 production in
ICARUS T600
p0 gg (at rest)
p- 40Ar n p0 X (2 GeV)
S0 p0 p (at rest)
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60 gg systems from 2 GeV p- interactions in LAr
gg systems from p0 at rest
gg systems from S ? p0 p decay
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Other MC-FLUKA simulations photons and electrons
1. Photons
2. Electrons
Number of events Angle ? (?) Angle ? (?) ltEnergygt (MeV) RMS EMC/ltEgt
1. Photon 50 MeV 1. Photon 50 MeV 1. Photon 50 MeV 1. Photon 50 MeV 1. Photon 50 MeV 1. Photon 50 MeV
10 60 120 49 2 1,02 0,06
2. Photon 100 MeV 2. Photon 100 MeV 2. Photon 100 MeV 2. Photon 100 MeV 2. Photon 100 MeV 2. Photon 100 MeV
45 60 120 99 5 1,01 0,06
10 30 90 96 4 1,04 0,04
10 64 116 100 5 1,00 0,03
10 0 60 98 5 1,02 0,03
10 120 180 96 4 1,04 0,04
3. Photon 300 MeV 3. Photon 300 MeV 3. Photon 300 MeV 3. Photon 300 MeV 3. Photon 300 MeV 3. Photon 300 MeV
10 60 120 292 9 1,03 0,02
4. Photon 1000 MeV 4. Photon 1000 MeV 4. Photon 1000 MeV 4. Photon 1000 MeV 4. Photon 1000 MeV 4. Photon 1000 MeV
10 60 120 994 22 1,01 0,02
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Simulation of p0 production in neutrino
interactions
p0 production from NC muon neutrino interaction
in the T600 was simulated using NUX-FLUKA chain
of programs.
Inc. energy 0 1 2 3 4 5 6
1 GeV 86 11 3
2 GeV 80 17 2 1
5 GeV 56 30 11 2 1
17 GeV 36 38 18 4 1 0 2
Multiplicity from primary vertex 100 events per
incident energy
Incident energy of p0 from primary interaction of p0 from secondary interaction
1 GeV 17 17
2 GeV 24 32
5 GeV 62 106
17 GeV 102 324
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gg invariant mass plots
Two photon 1.0, 1.5, 2.0 and 2.5 GeV muon
neutrino NC interaction
Two photon 5 GeV muon neutrino NC interaction
h0 correctly reconstructed
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Shower energy resolution (below 1 GeV)

• 142 showers
• survived the agreement criteria
• below 1 GeV
• not crossed by charged tracks.

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Conclusions
The analysis of p0 events in T600 is almost
finished scanning and measurements are concluded.
Reconstruction tools were validated through
MC-FLUKA simulations of several typologies of
events with p0 production.
The analysis demonstrates that with the LAr TPC
technology it is possible to well reconstruct
e.m. shower energies and p0 mass, also in the
difficult conditions of a surface run
The draft zero of this work is going to be
submitted to the Collaboration in sight of a
future publication