Physics coordination meeting summary report Emulsion simulation: GenIma Update of brick finding analysis  /e separation: test beam analysis HE cosmic ray muons, e/  identification and ν μ → ν e oscillations Multi-prong tau decay analysis Test at Fermilab in 2005 D.Duchesneau OPERA collaboration meeting Hamburg, June 6 th 2004 (on behalf of Pasquale) Original talks are accessible on OPERA file server.

Update of brick-finding analysis  The optimization of the neural network for the subclasses for CC and NC events is done.  The analysis for CC events was presented during the last meeting at Cern (December). A little improvement compared to the last results shown comes from an optimization for QE like events.   The analysis for NC events is completed as well. Two subclasses are defined: Long events and Short events (optimization for the taue QE).  The results are given in this presentation: the details will be given at the next collaboration meeting. Cern, 23/04/2004 C. Heritier

NN: wall probabilities Tracking: Fitted vertex error distribution (3D gaussian) Bricks 3D probability map + Convolution of the two probability distributions and integration on the volumes of the bricks Interaction brick found by selecting the one with the highest probability (more sophisticated strategies possible) Building the 3D bricks probability map: 1 23 (C.Heritier, Nov. 2003)

Update of brick-finding analysis  Application of the 3D map: 3 extraction strategies are tested Extraction of the highest probability brick (only 1 brick) Extraction of the second most probable brick if the vertex is not found under the condition P1-P2 < threshold (2 bricks) Extraction of all bricks with significative probabilities (cutoff at 1%) until the vertex is found. Cern, 23/04/2004 C. Heritier

Extraction strategy:  brick  Scanning overload (numuCC): Highest prob. Brick (HPB)73.5% proposal:73.0% - HPB + second most prob. Brick (SMPB), if P1-P2< % (+0.7%)1.9% HPB + SMBP, if P1-P2< % (+1.6%)3.4% HPB + SMPB, if P1-P2< % (+2.3%)4.4% HPB + SMPB, if P1-P2< % (+2.9%)5.5% HPB + SMPB, if P1-P2< % (+3.7%)6.4% HPB + SMPB, cutoff at 1%81.3% (+7.6%)13.0% All bricks, cutoff at 1%82.5% (+8.8%)16.9% Cern, 23/04/2004 Application of the 3D map for the  oscillated events. The results are for the mix of QE and DIS. The gain in efficiency is put in brackets.

Extraction strategy:  brick  e  brick  h Scanning overload (numu NC): Highest prob. Brick (HPB) 75.3% Proposal:80.1% 63.5% Proposal:69.8% 0% HPB + SMPB, if P1-P2< % (+3.1%)67.6% (+4.1%)8.9% HPB + SMPB, if P1-P2< % (+4.7%)69.4% (+5.9%)13.0% HPB + SMPB, if P1-P2< % (+5.5%)70.3% (+6.8%)16.1% HPB + SMPB, if P1-P2< % (+6.0%)71.0% (+7.5%)18.5% HPB + SMPB, if P1-P2< % (+6.6%)71.5% (+8.0%)20.6% HPB + SMPB, cutoff at 1% 83.6% (+8.3%)72.8% (+9.3%)30.8% All bricks, cutoff at 1% 84.8% (+9.5%)74.6% (+11.1%)53.6% Cern, 23/04/2004 Application of the 3D map for the  e and  h oscillated events.

Extraction strategy:  brick   brick  e  brick  h Total scanning overload (NC+CC) Additional mass reduction Proposal73.0%80.1%69.8%-- 1 brick73.5%75.3%63.5%-- 2 bricks (gain/proposal) 81.3% +8.3% 83.6% 3.5% 72.8% +3.0% 18.4%1.2% All bricks (gain/proposal) 82.5% +9.5% 84.8% +4.7% 74.6% %1.9% Cern, 23/04/2004 The total scanning overload is performed taking into account the rate NC/CC. The additional mass reduction of the target is estimated taking into account the mass reduction expected with the nominal beam. If only one brick is extracted, the efficiency for the  channel is a little greater than the proposal, for other channels, they are lower. But, if we decide to extract the second most probable brick, therefore the efficiencies are better than those of the proposal for all channels. For instance, if all bricks are extracted, for the  channel, the gain in efficiency is 9.5% - 1.9% = 7.6% better than the proposal.

 /e separation: pure pion test beam analysis Francesco Di Capua University of Naples Physics motivations Scanning of data from a pure pion test beam Data analysis (preliminary results) Outlook

Physics motivation Measure P(   e) Try to improve the technique in order to reduce the misidentification probability  e   h e Charm e  event wrong interpretation Low electron contamination pion beam needed  N   X e N  eCX

Current algorithm (1) Basic principle: rate of energy loss is different for electrons and hadrons: First part:  2 analysis : separator 1mm ~ 2mrad

Current algorithm (2) Second part: shower analysis Open a cone around the leading track Count segments inside the cone  energy measurement Check the compatibility between the momentum of the leading track, the energy of the shower and the particle hypothesis Other techniques Neural network

Pure  test beam 3 bricks exposed at different  momenta (2, 4, 6 GeV) Lead plate before focusing magnet with about 5 X 0 Lead glass calorimeter to monitor the electron contamination (10 -3 level) Muon contamination : 30% TB period (July 2003) TB design (G. De Lellis) Monte Carlo studies (G. De Rosa and A. Marotta) Electronic detector (I. Kreslo) Beam parameter tuning (G. De Lellis and I. Kreslo) Refreshing and Development (G. Rosa, C. Sirignano) Brick assembling (BAM) Brick exposure (M. Cozzi, G. De Lellis, G. De Rosa, I. Kreslo, L. Scotto, V. Tioukov,) People involved:

Scanning of data so far 2 bricks analyzed with the ESS 30 plates scanned for each brick (scanning surface: 2x2 cm 2 ) Hardware configuration (old prototype) Off-line analysis: FEDRA software Data are available on 2 GeV Pions

  Momentum measurement by MCS average beam momentum measurement Brick 1 (4 GeV)Brick 2 (2 GeV) =4.01  0.02 =1.96  0.01 ncell

Momentum measurement by MCS track by track Brick 1 (4 GeV) Tracks sample (nseg>=5) 1/P P P Brick 2 (2 GeV)

 2 analysis – preliminary results  2 e  2 2  = (95.8  0.5)% at 4 GeV  = (97.2  0.5)% at 2 GeV  =       0.3   =(94.0  0.5)% at 2 GeV   = (96.0  0.5)% at 4 GeV Taking into account for muon contamination (   =100%) 4 GeV

First MC studies (very preliminary)  2 MC / data comparison ( 4 GeV pions)  2 analysis result on MC events: 4 GeV   (%) GeV  GeV e76.8  2

Outlook Tune MC with data (instrumental backg. missing) Evaluate with MC the effect of cut on segments (nseg>4) Shower analysis Measurement of P(   e) for 2,4,6 GeV pions Other studies : detection of pion interactions (measurement of the background for  decay)

HE cosmic ray muons, e/  identification and μ → e oscillations Max Sioli, Physics Coordination Meeting, CERN 23 Apr 04 (Laurea Thesis of Antonio Petrella)

Outline of this study: Simulate HE cosmic ray muons inside OPERA (integrated in one year) and secondary particles generated by them; Compute the effect of these background tracks on the e/  Id; Example of application of this study: μ → e oscillation channel.

e  Example of a e CC event overlapping an e.m. shower Due to the huge number of secondary particles (Ekin_cut = 1 MeV), simulation has been restricted to 9 walls (3328 brick/wall): 8 insensitive volumes and 1 sensitive volume (in the center)

cone aperture = 50 mrad (A50) cone aperture = 250 mrad (A250) relative deviation wrt event axis =200 mrad (D200) releative deviation wrt event axis = 400 mrad (D400) For each emulsion: e/  Id: use of a NN is passed to the NN (using the prescriptions in the Laurea Thesis of L.S. Esposito)

Efficiency parametrized with: e/  Id: results

Energy reconstruction w/wo bg Number of tracks inside the cone is proportional to the shower energy

Energy resolution computed from: and parametrized with:

Impact of e.m. showers on CS This bg is not uniform as compton electron from lead. Here we considered 1 MONTH of fading time Similar results obtained using the strong fading model Strong fading model approximation: g(t) = g0exp(-t/  ) n

μ → e oscillation channel This computation has been performed according to hep-ph/ (therefore NOT a full simulation) The only differences are: –Signal efficiencies taken from Status Rep and CS note; –Signal efficiency computed with eId parametrizatrization; –Energy resolution smeared out according to parametrization;

In each ( sin 2 (2    m 23 2  ), we computed the curve  2   2  2 min = 4.61, corresponding to 90% C.L. Main contribution to the sensitivity arises from the poissonian fluctuations of bg event numbers. Nominal beam intensity (1.65 kt effective mass)

Multiprong tau decay channel analysis  Charm background (+ double charm)  kinematical analysis with likelihood variable taking into account correlations Differences with respect to the last presentation in Napoli - add short decays - use of more sophisticated likelihood analysis to take into account variables correlations - oscillated CNGS beam spectrum at  m 2 = eV 2 Muriele LAVY

 CC  CC charm  C charm Only one secondary vertex detected :  2.3% of these events a vertex is detected when the distance from this vertex to the others is higher than 15 microns |  d vertex |>15  m Double charm production in neutrino interactions  CC  CC charm  C charm SHORT DECAY  /charm With pre-selection cuts rad LONG DECAY

Multiprong tau decay channel analysis -  CC events with   3 hadrons  m 2 = 2.4  eV 2, 6.7  pot.year -1   5 events -  CC events with 1 charmed particles   264 events   7 events -  CC events with 2 charmed particles   10 events   events -  NC events with 2 charmed particles   3 events   events Number of events expected in OPERA detector per year  not detected + 1 secondary vertex with nprong=3  not detected + 1 secondary vertex with nprong=3 + 1 charm not detected 1 secondary vertex with nprong=3 + 1 charm not detected neglected

Multiprong tau decay channel Karlen method 1 1 Dean Karlen «Using projections and correlations to approximate probability distributions » arXiv:physics/ v Principle : probability distribution in multidimensional space built taking into account the correlations between variables improve discrimination power

Multiprong tau decay channel Karlen method long decay   variables used : - total transverse momentum - total energy - total angle - mass variable - jet energy - kink angle  purity efficiency 

Multiprong tau decay channel Karlen method short decays   variables used : - total transverse momentum - total energy - mass variable - jet energy  purity Efficiency 

Multiprong tau decay channel Karlen method Short + Long decays        short  long   short/long 

Multiprong tau decay channel  =  trig  brick   geom   vertex   id   short   kine  0.76  0.94   0.90  0.70    =  trig  brick   geom   vertex 2   id   long   kine  0.76  0.94   0.90  0.30   SHORT DECAY LONG DECAY  m 2 = eV 2 N  = 182  m 2 = eV 2 N  = 127 BR(  3h) = 15% N  h   N  h   years .BR=1.25% After analysis N charmcc 

Multiprong tau decay channel Hypothesis used :  kinematical obtained from the kinematical analysis with  m 2    eV   is the same for the others  m 2 in the table 5 years in the OPERA detector  3h  m2 (eV 2 ) back. N  h Feldman Cousins approach  -  h - h + h - 

Multiprong tau decay channel Channel Signal (  m 2 (eV 2 ) )  BR  BR Background e % % 0.31  % % 0.33 h % % h % % 0.44 Total % % 1.5 Hypothesis used :  R =1.25 % for the cinematic analysis with  m 2    eV   is the same for the others  m 2 in the table 5 years in OPERA detector

The OPERA test in 2005 on the NUMI beam D.Autiero, M. Komatsu CERN, 23/4/2004 Near detector

The beam is adjustable: by moving the horns and target, different energy spectra are available. 4x10 20 protons on target/year Near detector location:  LE beam: 1  CC / Kg /day  ME 2  CC / Kg /day  HE 3.2  CC / Kg /day 1 brick = 8.3 Kg > 1  CC / brick/hour In 2005 it is foreseen a period at HE for about 10% of the time Start of commissioning (5x10 12 protons/pulse) 20 November 2004 (1 month) Beam line components not cheched initially with the same accuracy as CNGS, will be debugged during commissioning Start of physics: January 2005 ?

OPERA test-beam: Two independent setups:  ECC array with old DONUT SFT detector (mini-OPERA) To collect the largest possible number of neutrino interactions in the bricks: Scanning technique practice (opera rehearsal), vertex studies,  0 reconstruction, multiple scattering, p& K ID use different passive materials (lead, iron), run for a long time also with LE beam, collaboration with the DONUT people SFT + MINOS for muon ID  Hybrid detector: get a few hundreds of well measured events in with: ECC+ Si trackers + ECAL + neutron detector + MINOS

Mini-OPERA

Hybrid sophisticated detector :  The high intensity of the NUMI beam at the near detector location allows to work with a small target mass and compact and sophisticated detectors (not possible with CNGS), made with all recycled components It is possible to build a precise detector around a single brick  It is a good occasion to perform a precise measurement of all what is produced in the neutrino interaction in the brick and to check also the production of backward particles which is relevant in OPERA for the BF analysis. We are interested in particular in the HE run  These results are also useful for the neutrino community for the investigation of nuclear effects, bricks can be made in Pb, Fe  This is not a new experiment (in competition with MINERVA) but just a test-beam performed with a small setup with the goal of collecting a few hundreds  CC well measured.

Precise tracking in the forward and backward direction Forward calorimetry Detector for backward neutrons ECC ECAL Minos near Detector (HCAL Muon ID) Detector for Backward Neutrals (scintillator bars) Silicon tracker planes Veto 1.5 m Max

The detector is made with existing/recycled components We can afford a sophisticated detector for one brick, given its small size. This is possible due to the high neutrino flux. The detector can fit in a space of 1.5 m longitudinal, < 1 m transverse which, can be available in between Minerva and Minos due to the MINOS ND coils (The magnetic field map should be checked). The idea is to change the brick exposed a few times per day (depending on the max number of interactions we want to accept per brick (HE run: 27 interactions per day). The neutron detector will be made of scintillator strips ‘we can recycle some of the TT building waste) with WLS fibers readout and M64 photomultipliers + standard opera TT electronics. The layers of strips will be crossed in X and Y.

For the neutron detector one possibility is to have just in the side close to the brick a thin foil of lead to be used as preshower in order to distinguish photons from neutrons. This could be put just at the beginning or after a few layers (2 layers) of scintillator in order to allow to detect some soft particles which would die in the lead (to be optimized with the ongoing simulation) Some passive material could also be introduced among the scintillator layers for a better containement, probably we will have to put an absorber in between the veto and neutron detector in order not to reject interesting events Pb, in this case put at the beginning ECC  n p Backward Neutron detector Eff=60% 50 planes of 8 strips 20 cm 400 channels

The Si tracker can be recycled from a CMS prototype The ECAL can be recycled from NOMAD lead-glass prototypes The trigger will be based on the ECAL + VETO In order to isolate the interactions really happening in the brick instead than in the ECAL or the neutron detector one has to look at the hit/tracks pattern in the Si tracker planes (check before the brick extraction) The connection with the events measured with the MINOS DAQ (as for the SFT detector) will be done on the basis of the time-stamp

Conclusions: (Dario on April 23rd 2004)  First discussions with the MINOS/FNAL people have already been performed, Komatsu presentation at MINOS coll. Meet.  We are writing, as requested by FNAL people, a MOU for this test which should be ready in a couple of weeks (about 10 pages)  This document is needed for FNAL in order to establish the use of resources (space, time schedule, electrical power, manpower, infrastructures) and the potential impact on the other programs  We are sorting out also the technical aspects related to MINOS (timestamp, B field)  The emulsion processing capabilities at FNAL have to be reactivated  On a long time scale some collaboration from local people (DONUT) to run the test is needed  This test can be quite useful for OPERA to learn about neutrino interactions in the bricks in a controlled way

The End