Experiment Proposal - opera - Infn

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Y(cm) -100 -120 -140 -160 -180 -200 -300 -200 -100 0 100 200 300 Z(cm) X(cm) -200 -220 -240 -260 -280 -300 -200 -100 0 100 200 300 Z(cm) Figure 74: Example of a τ → µ event. The 24 modules of target trackers have a negative Z coordinate. The broken lines are the results of the pattern recognition method described in the text. 104
5.5 Brick finding efficiency The selected brick is determined from the electronic tracker data in two steps. First, one tries to identify the right brick wall and then to find the brick to be removed in that wall. The application of the brick finding algorithm to the location of secondary interactions induced by neutral particles is in progress. The efficiency of each of the above steps has been evaluated by means of simulations. Test beam measurements have already been performed to validate these simulations (see Section 5.2) and other tests are planned for the future. 5.5.1 Wall finding An important issue determining the wall finding efficiency is back-scattering. Particles produced by the neutrino interaction may undergo reinteractions on nuclei and produce particles which go backwards with respect to the beam direction. This may lead to a wrong assignment of the wall where the neutrino interaction occurred. Simulations indicate that the fraction of events which show at least one back-scattered hit is higher for DIS than for QE events. This fraction also increases with the neutrino energy (Fig. 75 and Table 10). Table 10: Fractions of events with back-scattering and average wall finding efficiencies obtained with a neural network analysis. The statistical uncertainty on the back-scattering fractions is less than 0.5%. The uncertainty on the efficiencies is 0.2 − 0.3%. Event type mean back-scattering wall finding eff. eff. when adding fraction (%) (%) downstream wall (%) DIS ν µ CC 38.7 90.2 97.3 DIS ν µ NC 40.5 86.6 94.4 DIS τ → µ 40.0 90.7 96.4 DIS τ → e 44.8 92.9 97.4 DIS τ → no µ 51.9 90.5 95.9 QE ν µ CC 15.4 89.7 95.4 QE τ → µ 11.7 92.9 96.8 QE τ → e 18.1 95.9 98.2 QE τ → π 28.4 85.5 92.0 QE τ → ρ 29.6 93.8 97.2 Several algorithms have been developed to identify the interaction wall on an event-by-event basis: algorithms based on sequencial cuts on the number of hit strips per plane; topological methods to locate isolated back-scattered fired strips and neural networks. The neural network analyses give the best wall finding efficiencies, ranging from 85% to 96% according to the Monte Carlo simulations (Fig. 76 and Table 10). The SNNS [74] package was used to construct a network with eleven input nodes, twenty hidden nodes in one layer and 4 output nodes. We define the first wall of an event as the most upstream in 105
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CERN/SPSC 2000-028 SPSC/P318 LNGS P
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N. Bruski, S. Buontempo, F. Carbona
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Contents 1 Introduction 5 1.1 Physi
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6.7.1 Multiple scattering analysis
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1 Introduction In this document we
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eactor experiments (KAMLAND [22], B
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difference being the nature of the
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The total energy of electrons and
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through the decay topology and its
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Figure 6: Simulated ν τ event wit
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particles above 10 MeV . One can se
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vertex position as predicted by the
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• stability and maintenance: no p
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Figure 11: Illustration of the vari
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Table 3: Expected numbers of τ and
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3 The CNGS neutrino beam 3.1 The be
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per year of operation because the S
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ν µ at GS (p.o.t. GeV m 2 ) -1 10
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Figure 19: Generated (continuous li
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Emulsion Film + 56 (Lead + Emulsion
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The mechanical properties of the fi
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Figure 24: Film thickness distribut
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contact at different temperature an
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Figure 27: Photograph of a minimum
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entry : 85 RMS: 0.060 15 10 5 0 0 d
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[micron] 2 1 0 -1 -2 [micron] 2 1 0
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een searching for old emulsion plat
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Figure 33: Thickness distribution f
Page 57 and 58: Figure 35: RMS distribution of 472
Page 59 and 60: Figure 37: Wall support structure.
Page 61 and 62: ensures a well defined brick positi
Page 63 and 64: Figure 41: Detail of the brick mani
Page 65 and 66: The strips are 6.7 m long, 2.6 cm w
Page 67 and 68: the effective maximal length (for p
Page 69 and 70: Table 7: Characteristics of the 64-
Page 71 and 72: photomultiplier to be tested diaphr
Page 73 and 74: modate from 512 up to 5180 fibres.
Page 75 and 76: The fast shaper has a high gain in
Page 77 and 78: The Ethernet capable device provide
Page 79 and 80: R&D already performed by the MINOS
Page 81 and 82: Figure 54: Isometric view of the di
Page 83 and 84: Figure 56: Magnetic field distribut
Page 85 and 86: RPC layout 8.00 m 8.75 m Figure 58:
Page 87 and 88: formance, it is presently foreseen
Page 89 and 90: Figure 61: Drift plane arrangement
Page 91 and 92: Figure 63: Schematic view of a XPC
Page 93 and 94: Figure 64: Acceleration spectrum fo
Page 95 and 96: Figure 65: The OPERA detector shown
Page 97 and 98: Table 9: Number of electronic chann
Page 99 and 100: Adjustable gain Channel 0 Sample &
Page 101 and 102: Trigger OUT IN Discri. Time Ref. PP
Page 103 and 104: Super Module 1 Super Module 2 Super
Page 105 and 106: 5 Analysis of the electronic detect
Page 107: Track segments on both the emulsion
Page 111 and 112: Wall finding efficiency 1 0.95 0.9
Page 113 and 114: The worst case leading to the lowes
Page 115 and 116: electromagnetic showering events an
Page 117 and 118: Studies on the strategies have star
Page 119 and 120: which may enter in such a compariso
Page 121 and 122: Figure 84: The total brick finding
Page 123 and 124: Figure 86: Charge determination of
Page 125 and 126: Figure 89: Muon momentum resolution
Page 127 and 128: Figure 91: Muon momentum resolution
Page 129 and 130: Reconstructed Pion Energy N Analog
Page 131 and 132: Figure 98: The difference between r
Page 133 and 134: By using the above running modes of
Page 135 and 136: µm EXP.: DONUT 3039/01910 MOD.:ECC
Page 137 and 138: emulsion film plastic foils and edg
Page 139 and 140: 200micron base 50micron emulsion la
Page 141 and 142: Figure 106: Tracking efficiency of
Page 143 and 144: a base track on film 2 a penetratin
Page 145 and 146: Long decays, defined as a decay top
Page 147 and 148: more than 60 views/s recognising al
Page 149 and 150: Table 12: Basic numbers used to des
Page 151 and 152: an area that one S-UTS can process
Page 153 and 154: unit cell L=1300micron Pb plate ( 1
Page 155 and 156: We recall that the intrinsic positi
Page 157 and 158: Figure 116: The top histograms show
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The error on θ S due to both the s
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Figure 120: Fraction of pions which
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#1 #2 #3 #4 #5 γ γ ∆θ 4= |θ 5
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Figure 124: Energy resolution for e
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Figure 126: Efficiency for γ’s t
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7 Physics performance 7.1 Electron
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7.2 Muon identification efficiency
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Table 13: Muon identification effic
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Table 14: Brick finding efficiency
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The second result is obtained from
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Figure 134: Brick-to-brick connecti
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Figure 136: Distribution of τ deca
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For long decays the overall efficie
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The φ angle is expected to peak at
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Table 19: Summary of the kinematica
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known. Because of these uncertainti
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Table 21: Expected charm background
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π− e+ γ e- e+ e- γ π− Figur
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Table 24: Estimates of the rate of
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Table 27: Expected numbers of τ an
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Table 28: Sensitivity at the 90% CL
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7.6 Determination of the oscillatio
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measurement of the ratio between ν
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Table 30: Neural network recognitio
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(mrad) 0.04 0.02 0 -0.02 -0.04 10 2
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Table 31: Radioactivity measurement
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ick. There is approximately a facto
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Figure 152: A typical PMT response
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1m π, µ 15 GeV/c mini-walls 1.6 m
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Electrons 1GeV/c 20mm Pb Number of
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tube. An Image Intensifier (II) by
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1 0 0 l = 1 1 .8 m N, p.e. 1 0 1 0
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HPD’s pixels (Fig. 162). The cook
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A complete system has been designed
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The acquisition system (VA-DAQ) use
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The upstream tracker T 1-3 between
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Figure 168: Distributions of the ap
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Figure 169: Example of a large-angl
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multiple scattering, given the smal
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9.1.3 Wall support structures An al
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Nevertheless, the possibility to us
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Figure 174: (a) 3D view of the spec
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9 p.e. and 6.9 p.e. at a distance f
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Figure 176: Neutrino induced charm
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A test programme for emulsion brick
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The space requirements in the exper
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advance. The sets of scintillator s
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Task Name Start Finish Study of mai
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11 Experimental infrastructure 11.1
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After the exposure to cosmic rays,
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on the size of these stations. A co
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Table 38: Expected contributions to
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the developed emulsions and to stan
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As the sensitivity is not limited b
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[26] M. Apollonio et al., Phys. Let
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[89] http : //tosca.web.cern.ch/T O
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