Operation of and results from OPERA Ciro Pistillo LHEP Bern University CHIPP Plenary meeting Lausanne, EPFL-LPHE September

The swiss participation in OPERA 2 INSTITUTIONS, 17 PHYSICISTS CHIPP Plenary meeting C.Pistillo - Bern Univ. 2 A. Badertscher C. Lazzaro A. Rubbia T. Strauss A. Ariga T. Ariga A. Ereditato J. Knüsel F. Juget * I. Kreslo G. Lutter * F. Meisel * U. Moser M. Messina C. Pistillo K. Pretzl J.L Vuilleumier * * previously forming the Neuchatel group, moved to Bern in August LHEP ETHZ (OPERA: 35 institutions, ~200 physicists)

OPERA is designed for the direct observation of  appearance in a pure ν μ beam in order to provide a final confirmation of neutrino oscillations in the atmospheric sector Physics goal best fit: CHIPP Plenary meeting C.Pistillo - Bern Univ. 3

The Cern Neutrino to Gran Sasso (CNGS) beam L=730 km ; =17 GeV ( e+ e)/  =0.7%  = 2% 730 Km CERN LNGS CHIPP Plenary meeting C.Pistillo - Bern Univ. 4 C.Borer Diploma thesis (LHEP) preliminary

Detection of the  appearance signal Two conflicting requirements:  Large mass  low Xsection  High spatial resolution  signal selection, background rejection   -- Decay “kink”  -- ~1 mm  oscillation -- CHIPP Plenary meeting C.Pistillo - Bern Univ. 5 h-h- e-e-

8.3 Kg Pb Emulsion layers  1 mm 10 X0’s The OPERA target is composed of ~ bricks The OPERA target CHIPP Plenary meeting C.Pistillo - Bern Univ. 6 

Veto plane (RPC) Spectrometer: XPC, HPT, RPC, magnet SM1 SM kton OPERA : a hybrid detector Target and Target Tracker CHIPP Plenary meeting C.Pistillo - Bern Univ. 7

Brick handling Brick Manipulator System Xray machine  Brick extraction  XRay exposure (local reference frame) CHIPP Plenary meeting C.Pistillo - Bern Univ. 8

Chemical plant for emulsion development A dedicateted LNGS CHIPP Plenary meeting C.Pistillo - Bern Univ. 9

Automated emulsion analysis Swiss Scanning LHEP Fully unattended emulsion scanning. 40 microscopes in OPERA 2 cm LHEP Bern: Swiss Scanning Station with 5 microscopes. ~10 physicist from Bern and ETH Zürich involved. Goal: analyze ~ 20% of the total OPERA bricks statistics (700/1000 brick/year). CHIPP Plenary meeting C.Pistillo - Bern Univ. 10

Strategy for event analysis h muon 2 cm 2 mm 2 cm CHIPP Plenary meeting C.Pistillo - Bern Univ m

Status of the experiment data taking May 2006: electronic detectors commissioning Aug 2006: technical run, 0.76*10 18 pot collected 319 interactions in the rock, mechanical structure and iron of the spectrometer Oct 2006: start of brick production Oct 2007: pilot physics run (~40% target) 0.82*10 18 pot first 38 neutrino events in the target Jun 2008: OPERA detector filled and fully commissioned, bricks inserted ( by end 2008) Jun 2008: Start first OPERA production run Sep 2008: 5.6*10 18 pot and ~500 neutrino events in the target CHIPP Plenary meeting C.Pistillo - Bern Univ year CNGS nominal 4.5*10 19 pot

Event :  CC interaction 5 prongs = 9  m Electromagnetic shower pointing to the vertex (  conversion) 19 m 8 m 43 mm 17 mm CHIPP Plenary meeting C.Pistillo - Bern Univ. 13

24 mm 8 mm Em. Shower E = 4.7  1.3 GeV Event located in Bern – first (only) e candidate Neutrino vertex IP = ~  m CHIPP Plenary meeting C.Pistillo - Bern Univ. 14

Flight length: μm  kink : rad P daughter : 3.9 ( ) GeV P T : 796 MeV (> 606 MeV ) Two e. m. showers pointing to vertex Clear kink topology + EM shower Event : a charm candidate CHIPP Plenary meeting C.Pistillo - Bern Univ. 15

OPERA ν τ observation probability CHIPP Plenary meeting C.Pistillo - Bern Univ. 16 SK 90% CL (L/E analysis) observation probability % MINOS 3 σ sensitivity 4 σ sensitivity OPERA event 0.8 BG (5 full CNGS years)

The 2008 OPERA run Expectations: 127 days for the CNGS 2.3*10 19 p.o.t Total number of interactions 2660  CC events 2000  NC events 600 e  e events 17 Charm decay84 Tau candidate eV 2 ) 1.0 Current situation (Aug 31th) After 68 days: 5.6*10 18 p.o.t ~45% of what originally expected CHIPP Plenary meeting C.Pistillo - Bern Univ *10 18 p.o.t JUNESEPT

Past activities of the Swiss researchers  conceptual design  proposal  CNGS beam design and optimization  construction of the Target Tracker  lead production monitoring  development of European microscopes  emulsion film robot  test beams  physics analysis  … CHIPP Plenary meeting C.Pistillo - Bern Univ. 18

Responsibilities of the Swiss researchers Management of the experiment: A.Ereditato (spokesperson), U. Moser (member of publication committee) Emulsion scanning: Largest scanning team in Europe (~10 physicist) and ~20% brick scanning at LHEP Data Analysis responsabilities: Electron identification, shower reconstruction,  0 detection and  search in  -> e channel Other Analysis activities: Strategies for neutrino interaction vertex location for muon-less events Determination of neutrino energy spectrum Charm event studies CHIPP Plenary meeting C.Pistillo - Bern Univ. 19

Education PhD thesis in progress: J. Knüsel (LHEP): low momentum muon identification C. Lazzaro (ETHZ): determination of the CNGS neutrino energy spectrum from CC events reconstructed with the electronic detectors F. Meisel (LHEP): measurement of the e contamination of the CNGS beam T. Strauss (ETHZ): neutrino induced charmed particle decays CHIPP Plenary meeting C.Pistillo - Bern Univ. 20

-The whole detector is fully commissioned -The concept of the OPERA detector is experimentally validated The first physics run started in June - After 68 days 5.6*10 18 p.o.t have been collected ~ 500 neutrino interactions have been triggered by electronic detectors and are being analyzed in the scanning laboratories Conclusions Interesting topologies detected (charmed particle decay, prompt e ) We just miss the tau! Chance to observe the first  candidate event with 2008 run? CHIPP Plenary meeting C.Pistillo - Bern Univ. 21

BACKUP SLIDES

τ search : Backgrounds  -- ,e ,e - +e+h++e+h+ D+D+ Same decay topology as  Charm production in CC, common to the 3 channels Good muon identification is fundamental Primary lepton not identified Coulombian large angle scattering of muons in Lead : Bck. to     Hadronic interactions in Pb: Bck. to  h or to    if hadron mis- identified as muon) Expected number of background events after 5 years running with nominal beam: h h τeτeτμτμτhτhτ  3h Total Charm background Large angle μ scattering.096 Hadronic background Total per channel

  e oscillation search   e oscillation search  13 SIGNAL e beam   e  NC  CC 9° ° °  m 23 2  m 23 2 = 2.5 x eV 2  23 = 45° nominal CNGS beam Combined fit of E e, E vis, (pt) miss to improve S/B ratio 90% C.L. limits on sin 2 (2  13 ) and  13 : sin 2 (2  13 )<0.05  13 < 7.1º 5 years (pt) miss GeV 2.5x10 -3 eV o 6.4 o