Current Status of The OPERA Experiment (Oscillation Project with Emulsion tRacking Apparatus) Kunihiro Morishima morishima@flab.phys.nagoya-u.ac.jp Nagoya university On behalf of OPERA collaboration NNN08

The OPERA Experiment Motivation and Conceptual Design ・ OPERA (Oscillation Project with Emulsion tRacking Apparatus) is a long baseline neutrino oscillation experiment ・ The goal of the experiment is to directly measure for the first time neutrino oscillation in an appearance mode ・ Using an almost pure νμbeam, the νμ→ντ transition is detected by observing the τ lepton decay, induced after a neutrino-lead CC interaction ・ τ lepton decay is observed by means of Emulsion Cloud Chambers ・ The detector is located on the CNGS (CERN to Gran Sasso) beam line at a distance from the neutrino source of 730 km

The CNGS beam 730km The beam is optimized for  t appearance in the atmospheric oscillation region Δm232 = (2.43±0.13)×10-3 eV2 sin22θ23 = 1.0 CERN SPS conventional  beam  ( m-2 / pot) 7.45x10-9  CC / pot / kton 5.44x10-17 < E > ( GeV ) 17 (e + e) /  0.85 %  /  2.0 % t prompt negligible 730km INFN Gran Sasso Institute

Principle of detecting tau neutrino nt Topology ～ 10-13 s cτ = 87 micron nt Kink t-　→　e- 17.8 ％ t- 　→　μ- 17.4 ％ t- 　→　h- 49.5 ％ Trident t- 　→　h- h- h+ 15.2 ％ nt t- m-, e-, h- h h Micrometric and milliradian resolution → Emulsion Large Mass → Lead Target Trigger Neutrino Interaction → Target Tracker Identify muons and charge to reduce charm backgound → Spectrometer ECC Electronic Detector Hybrid Detector (Emulsion - Electronic Detectors)

t identification Pb Neutrino 125mm 100mm Tau Decay 75.4mm II 10 X0 ECC Target is divided in about 152000 ECC’s 1 mm 125mm 100mm Tau Decay t n Pb Emulsion layers 75.4mm II 10 X0 lead plate ECC （Emulsion Cloud Chamber） Piled up alternately Nuclear Emulsion (OPERA film) ～ 8.3 kg

The OPERA Film The OPERA film position resolution ～ 50nm Sub micron crystal 3D tracking device 50 micron Microscopic Image Recorded as silver grain along the line particle passed through sensitivity : 36grains/100micron emulsion (44 μm) plastic base (205 μm) position resolution ～ 50nm

Tau Neutrino Interaction In ECC by DONUT

Sensitivity of tau neutrino detection Full mixing after 5 years run at 4.5x1019 pot / year - decay channels Signal (Full mixing) Background m2 2.5 x 10-3 (eV2) 3.0 x 10-3 (eV2) -  µ- 2.9 4.2 0.17 -  e- 3.5 5.0 -  h- 3.1 4.4 0.24 -  3h 0.9 1.3 ALL 10.4 15.0 0.76 Background sources: 　- Charm production and decays - Hadron re-interactions in lead - Large-angle muon scattering in lead Muon ID by electronic detector

Design of The OPERA Detector Super Module 1 Super Module 2 CNGS Beam 10m 20m 10m Target (ECC + Target Tracker) Spectrometer Located in Hall C - INFN Gran Sasso Institute

The OPERA Detector - overview - Emulsion - Counter Hybrid Detector ・ ECC （Brick Target） ・ Target Tracker ・ Spectrometer 　　　　＋ ・ Scanning System （Read-out Emulsion） SM 2 SM 1 Located in Hall C - INFN Gran Sasso Institute

Brick Target Target mass 1.35 kt ~ 150000 Bricks ~ 8 millions of The OPERA detector Brick Target Target mass 1.35 kt 　~　150000 Bricks 　~　8 millions of nuclear Emulsion Brick filling is finished in July 2008: 5000 bricks more will be added at the end of 2008 once additional lead will be delivered

BAM （Brick Assembling Machine） The OPERA detector BAM （Brick Assembling Machine） Production of ECC Working in a dark room Speed ~700 bricks/day

BMS （Brick Manipulating System） The OPERA detector BMS （Brick Manipulating System） Loading and Extraction of ECC

The OPERA detector Electronic Detector Spectrometer Target Tracker

L. Scotto Lavina (INFN Napoli) The OPERA detector Target tracker The main goals of the target tracker are the trigger on the neutrino events and the identification of the brick to be extracted and then analysed It is made of plastic scintillator strips, each with a wavelength shifting fibre The fibres are connected in groups of 64 to multi-anode Hamamatsu PMTs at both ends Spatial resolution ~0.8 cm (2.6 cm pitch) L. Scotto Lavina (INFN Napoli)

L. Scotto Lavina (INFN Napoli) The OPERA detector Spectrometer The goal of the spectrometer is the momentum measurement and charge discrimination In particular it is used to measure and identify muons, in order to reduce charm background It is made by inner tracker (RPC planes) and precision tracker (Drift Tubes) in a 1.5 T magnetic field B B L. Scotto Lavina (INFN Napoli)

The automated microscopes ~30 bricks will be daily extracted from the target and analyzed European scanning system S-UTS (Japan) Scanning speed: 20cm2/h Scanning speed: 72cm2/h High speed CMOS camera (3 kHz) Piezo-controlled objective lens Customized commercial optics and mechanics Hardware corded algorithm (FPGA) asynchronous DAQ software asynchronous DAQ software Data Base Central Data Base Data Base

Today ! ～ 6.0E18 pot ～500 bricks already tagged (expected : 2200 bricks)

2008 Run : One Example of Neutrino Event

2008 Run : One Example of Neutrino Event extraction The most probable brick is detected by brick finding algorithm Development → Scanning CS ECC ν

CS analysis by the Scanning Station The Scanning Station scans the whole surface of the two emulsion interfaces (CS) and selecting particle tracks found in both plates 2 plates Trkid TX TY PX PY 1 -0.137 0.1947 114701.2 52702.3 2 0.0179 -0.0572 116835.9 49218.7 3 0.0987 0.0407 117907.0 50627.8 CS result validates the brick, which is then sent to the developing facility

Location of the neutrino interaction in ECC Predictions from the CS are followed back in the brick, looking for the position where the neutrino interaction occurred. Neutrino Beam ECC brick CS

Vertex Reconstruction in ECC Z Tracks found in ECC Reconstructed track parameter at vertex Ax Ay IP -0.1336 0.1822 4.0 0.0194 -0.0701 2.1 0.0893 0.0367 1.8 -0.0250 -0.0034 10.0 VTX:(116213.5 51204.3 63617.2) X Y The vertex is confirmed and all data are stored into the DB

2007 Run : a charm candidate ! Electromagnetic shower (15 GeV)

Summary and Future The OPERA detector is taking data now OPERA proved the possibility of producing emulsion detector at the kiloton scale Stream of locating Neutrino Interactions is systematically running continuously. Now: run 2008 started since June 18th, 123 days of data taking Expected 2.28x1019 p.o.t. and 1 nt interaction So far, collected 6x1018 p.o.t. The 2008 run will produce important results for OPERA : events for efficiency and BG estimates (charm,…) and maybe ~1 nt ???