Last Update: October 2000

OPERA

THE COLLABORATION

Aichi Educational University, Aichi, Japan (K. Kodama, N. Ushida);

METU, Ankara, Turkey (M. Guler, M. Serin-Zeyrek, P. Tolun, M.T. Zeyrek);

LAPP and Université de Savoie, Annecy, France (D. Duchesneau, A. Degre, J. Favier, H. Pessard);

INFN and Bari University, Bari, Italy (M. De Serio, M.T. Muciaccia, P. Righini, S. Simone);

IHEP, Beijing, China PR (S.L. Lu, S.J. Zhou);

Humboldt University,Berlin, Germany (K. Winter);

Bern University, Bern, Switzerland (C. Haeberli, M. Hess, R. Klingenberg, U. Moser, K. Pretzl, T. Waelchli, M. Weber);

INFN and Bologna University, Bologna, Italy (G. Giacomelli, G. Mandrioli, L. Patrizii, P. Serra, M. Sioli, G. Sirri);

IIHE (ULB-VUB), Brussels, Belgium (G. Van Beek, P. Vilain, G. Wilquet);

Laboratori Nazionali di Frascati, INFN, Italy (M. Spinetti, L. Votano);

Toho University, Funabashi, Japan (S. Ogawa, H. Shibuya);

CERN, Geneva, Switzerland (D. Autiero, L. Camilleri, L. Di Lella, J. Dupraz, J.P. Fabre, R. Petti, P. Schilly);

Märkische Fachhochschule FB Elektrotechnik, Hagen, Germany (K. Schauties, H. Sohlbach, H. Woltersdorf);

Israeli group c/o Technion, Haifa, Israel (J. Goldberg, M. Khalifa);

Hamburg University, Hamburg, Germany (F. W. Buesser, A. Geiser, A. Garfagnini, K. Höpfner, B. Koppitz, B. Naroska, W. Schmidt-Parzefall, R. van Staa);

Kobe University, Kobe, Japan (S. Aoki, T. Hara);

IPNL, IN2P3-CNRS and Université C. Bernard Lyon I, Villeurbanne, France (L. Chaussard, M. Chemarin, Y. Déclais, P. Jonsson, S. Katsanevas, I. Laktineh, J. Marteau, G. Moret);

Münster University, Müenster, Germany (N. D'Ambrosio, P. Boschan, D. Frekers, D. Rondeshagen, J. Schmand, H. J. Wörtche, T. Wolff);

Nagoya University, Nagoya, Japan (K. Hoshino, M. Komatsu, M. Miyanishi, M. Nakamura, T. Nakano, K. Niwa, O. Sato);

INFN and "Federico II" University, Naples, Italy (N. Bruski, S. Buontempo, F. Carbonara, A.G. Cocco, G. De Lellis, A. Ereditato, G. Fiorillo, T. Kawamura, M. Messina, P. Migliozzi, P. Strolin, V. Tioukov);

Laboratoire de l'Accélérateur Linéaire (LAL), IN2P3-CNRS and Université Paris-Sud, Orsay, France (J.E. Campagne, B. Merkel, J.P. Repellin, J.J. Veillet);

INFN and Padova University, Padova, Italy (R. Brugnera, F. Dal Corso, S. Dusini, L. Stanco);

INFN and "La Sapienza" University, Rome, Italy (G. Rosa)

Fachbereich Physik der Universitaet Rostock, Rostock, Germany (M. Beyer, H. Schroeder, R. Waldi);

INFN and Salerno University, Salerno, Italy (E. Barbuto, C. Bozza, G. Grella, S. Sorrentino, G. Romano);

Institut de Recherches Subatomiques, IN2P3-CNRS/ULP BP20, Strasbourg, France (R. Arnold, M. Dracos, J.L. Guyonnet, R. Strub);

Shandong University, Tsinan (Shantung), China PR (M. He, J.Y. Li, C.F. Feng, Y. Fu, L. Xue);

Utsunomiya University, Utsunomiya, Japan (Y. Sato, I. Tezuka);

Rudjer Boskovic Institute (IRB), Zagreb, Croatia (M. Stipcevic, A. Ljubicic, K. Jakovcic).

1) GOAL OF THE EXPERIMENT

The goal of OPERA (Oscillation Project with an Emulsion tRacking Apparatus), presently in the phase of approval by INFN, is the search for nm-nt oscillations with a long baseline t appearance experiment in the approved CNGS neutrino beam from the CERN SPS to the Gran Sasso Laboratory. The experiment should be able to test the so-called atmospheric neutrino anomaly, reported by the Super-Kamiokande experiment.

The detector is based on the so-called ECC technique, a massive sandwich of lead plates and emulsion films, used as high space resolution tracking devices. Electronic detectors complement the experimental set-up, with the task of predicting the neutrino interaction point inside the sandwich structure elements (bricks) and to identify muons and measure their charge and momentum for background rejection (spectrometers). The detector is based on a modular structure: about 235000 bricks are assembled in walls, in turn forming supermodules, each equipped with a muon spectrometer. The total detector is composed of three supermodules totalling a mass of about 2000 tons.

The sensitivity of OPERA in the oscillation parameters covers the region indicated by Super-Kamiokande. About 18 t events are expected in five years of standard CNGS running with a background of 0.6 events if oscillations occur at the central value indicated by Super-Kamiokande (sin22q=1 and Dm2=3.2x10-3 eV2). The low expected background contributes to the high discovery potential of the experiment.

2) PHYSICS ACHIEVEMENTS DURING 2000

The experiment has been in its design phase in 2000 with the aim of producing the Experiment Proposal, which has been submitted to the Scientific Committees in July 2000.

The activity of the Collaboration concerned the design of the experiment and the assessment of its expected performance by simulations and test measurements performed on prototype detectors (emulsion bricks and electronic detectors) exposed to particle beams.

In addition to the general properties of the newly developed industrial emulsion films (sensitivity, ageing features, controlled erasing, etc.), we have studied: the hit-brick finding efficiency by electronic trackers, the vertex finding efficiency (by scanning the emulsion films in the brick), the particle ID by measurement in the emulsions and the determination of the momentum by multiple scattering measurement in the lead/film sandwich structure. In parallel, we performed measurements with RPC and scintillator strip detectors and started the realisation of a dipolar magnet prototype.

Another R&D activity concerned the development of next generation automatic scanning devices. The first prototype of the S-UTS system being developed in Japan is expected to be operational in 2001. It will feature a scanning speed of more than 10 cm2 of emulsion film surface per hour, meeting the OPERA requirements. Another system is being developed in Italy with similar expected features, based on the so-called multi-track approach.

We also started the work on technical issues such as the support structure of bricks and electronic detectors, the automation related to the brick assembly and installation, and the handling of the emulsion films before the run (erasing of background tracks) and after (development).

3) INFN CONTRIBUTION TO THE EXPERIMENT IN TERMS OF MANPOWER AND FINANCIAL SUPPORT

25 researchers from the Italian groups contributed to the OPERA activities in 2000 (nearly 10 FTE). We profited from the technical support from the Sezioni INFN: technical design (LNF, Napoli, Padova), emulsion and brick handling (Bari, Roma, Salerno), electronic detectors (LNF, Padova), electronics design (Napoli, LNF, Padova). Local support was also given to the R&D activities on automatic scanning (Bari, Napoli, Roma, Salerno). A contribution was given by the technical services of the LNGS for setting up the emulsion laboratory at Gran Sasso and to perform radioactivity measurements on the site.

The financial support from INFN amounts to 657 ML.

4) NUMBER OF PUBLICATIONS IN REFERRED JOURNALS

No publications in refereed journals. Notable reference:

Experiment Proposal: M.Guler et al., OPERA, an appearance experiment to search for nm-nt oscillations in the CNGS beam, CERN/SPSC 2000-028; SPSC/P318,; LNGS P25/2000, July 10, 2000.

5) NUMBER OF TALKS TO CONFERENCES

3 talks:

Epiphany Conference on Neutrinos in Physics and Astrophysics, Cracow, 6-9 January 2000;

NOW 2000 (Neutrino Oscillation Workshop), Conca Specchiulla, 9-16 September 2000;

DM 2000 (Dark Matter Conference), York, 18-22 September 2000.

6) NUMBER OF UNDERGRADUATE AND DOCTORAL THESIS ON THE EXPERIMENT

Concerning the Italian groups:

1 Laurea Thesis in Physics completed. 5 Laurea Thesis in progress; 1 Doctoral Thesis in progress.

7) LEADERSHIP ROLE IN THE EXPERIMENT

In the present organisational scheme:

Member of the Executive Triumvirate: P. Strolin;

Contact Person: A. Ereditato;

Working Groups Organisers: S. Buontempo, P. Migliozzi, G. Romano, M. Spinetti.

8) INNOVATIVE INSTRUMENTS

Innovative instrumentation is being developed in two main fields related to the operation of the detector at Gran Sasso and to the analysis of the emulsion films. Specialised industry has been involved.

Automation:

computer controlled systems for emulsion brick packing and handling;

automatic devices for high speed and high precision movements (microscope mechanics).

High definition image analysis:

New generation CCD cameras with high frame rate and high image quality;

New multi-processor frame grabbers for on-line image analysis.

9) COMPETING EXPERIMENTS

Other planned, approved or running long baseline neutrino oscillation experiments with the aim of studying the atmospheric neutrino deficit with terrestrial experiments are:

Super-Kamiokande in Japan with the K2K beam from KEK;

MINOS in Minnesota with the NuMI beam from FERMILAB;

ICARUS at Gran Sasso with the CNGS beam from CERN.

K2K is running and can perform a disappearance search for neutrino oscillations, as well as MINOS, starting from 2003. ICARUS can study nm-nt oscillations with an appearance experiment based on the kinematical selection of the t signal. OPERA will be the only experiment able to directly identify the t decay topology through the detection of its (short) track with the emulsion films. The experiment will start running in 2005.

10) INTERNATIONAL COMMITTEES WHICH HAVE REVIEWED THE EXPERIMENT

The OPERA Letters of Intent and the Experiment Proposal (which can be found on the web: http://opera.web.cern.ch/opera/) have been reviewed by the CERN Super Proto Synchrotron Committee (SPSC) and by the Gran Sasso Laboratory Scientific Committee (LNGSSC).