Last Update: October 2000

Large Volume Detector (LVD)

Collaboration

M.Aglietta14, E.D.Alyea7, P.Antonioli1, G.Badino14, G.Bari1, M.Basile1, V.S.Berezinsky9, F.Bersani1, M.Bertaina14, R.Bertoni14, G.Bruni1, G.Cara Romeo1, C.Castagnoli14 , A.Castellina14 , A.Chiavassa14, J.A.Chinellato3, L.Cifarelli1,* , F.Cindolo1, A.Contin1, V.L.Dadykin9, L.G.Dos Santos3, R.I.Enikeev9, W.Fulgione14, P.Galeotti14, P.Ghia14, P.Giusti1, F.Gomez14, F.Grianti1, G.Iacobucci1, E.Kemp3, F.F.Khalchukov9, E.V.Korolkova9, P.V.Korchaguin9, V.B.Korchaguin9, V.A.Kudryavtsev9, M.Luvisetto1, A.S.Malguin9, T.Massam1, N.Mengotti Silva3, C.Morello14, R.Nania1, G.Navarra14, L.Periale14, A.Pesci1, P.Picchi14, I.A.Pless8, A.Romero14, V.G.Ryasny9, O.G.Ryazhskaya9, O.Saavedra14, K.Saitoh13, G.Sartorelli1, M.Selvi1, N.Taborgna5, N.Takahashi12, V.P.Talochkin9, G.C.Trinchero14, S.Tsuj10, A.Turtelli3, P.Vallania14, S.Vernetto14, C.Vigorito14, L.Votano4 , T.Wada10, R.Weinstein6, M.Widgoff2, V.F.Yakushev9 , I.Yamamoto11, G.T.Zatsepin9 , A.Zichichi1.

1 University of Bologna and INFN-Bologna, Italy

2 Brown University, Providence, USA

3 University of Campinas, Campinas, Brazil

4 INFN-LNF, Frascati, Italy

5 INFN-LNGS, Assergi, Italy

6 University of Houston, Houston, USA

7 Indiana University, Bloomington, USA

8 Massachusetts Institute of Technology, Cambridge, USA

9 Institute for Nuclear Research, Russian Academy of Sciences, Moscow, Russia

10 Okayama University, Okayama, Japan

11 Okayama University of Science, Okayama, Japan

12 Hirosaki University, Hirosaki, Japan

13 Ashikaga Institute of Technology, Ashikaga, Japan

14 Institute of Cosmo-Geophysics, CNR, Torino, University of Torino and INFN-Torino, Italy

* now at University of Salerno and INFN-Salerno, Italy

Laboratory: LNGS

1. Goal of the experiment.

The LVD experiment was conceived with a twofold purpose: the study of high energy cosmic ray processes deep undergound and the study of low energy neutrino bursts, typically originated in the Super Nova gravitational stellar collapses. The experiment has been taking data in the Gran Sasso Laboratory since June 1992 and has performed a number of interesting measurements and observations relative to high energy muons over a very wide slant depth interval ranging from 3000 to 20000 m.w.e.. At the same time the LVD experiment has been monitoring with ever increasing active mass for Super Nova gravitational stellar collapses over 95% of the Galaxy. No such event has been up to now detected.

Today, the LVD apparatus comprises a 1 kiloton liquid scintillator mass and the main goal of the experiment, remains the study of Super Nova gravitational stellar Collapses. As a matter of fact, even today, LVD represents the most powerful instrument based on liquid scintillator for the study of low energy neutrino bursts.

LVD is sensitive not only to the interactions of anti-n e with the liquid scintillator free protons but also to the charged and neutral current interactions with the scintillator C nuclei. The comparison of the number of interactions and of the neutrino energy spectra in the various LVD channels, coupled to analogous information from other experiments, will allow not only for the detailed study of the gravitational collapse dynamics of massive stars, of the Super Nova explosion mechanism, of the EOS of matter at nuclear densities, but for the study of the neutrino masses as well.

Since February 1999, LVD has joined the SNEWS (Super Nova Early Warning System) network. The purpose of this project, carried out by the major experiments sensitive to neutrino bursts (AMANDA, LVD, MACRO, SNO, SuperKamiokande) is to provide an early Super Nova alert to the astronomers based on the coincident neutrino burst signal from a number of experiments.

2. Physics achievements during 2000.

The LVD experiment has taken data with an average duty cycle of more than 99% monitoring the Galaxy for Super Nova stellar collapses. No such event has been observed.

For the first time it has been possible to search for the presence of neutrinos in association with an observed g-ray burst. The absence of a neutrino signal has allowed, with some assumptions, to constrain the neutrino emission from the g-ray burst sources.

3. INFN contribution to the experiemnt in terms of manpower and financial support.

-Manpower: 27 researchers (10.3 FTE), 8 technicians (3 FTE)

-Financial Support: 680 Mlit

4. Number of publications in refereed journals: 1

5. Number of talks to Conferences: 3

6. Number of undergraduate and doctoral theses on the experiment

Laurea diplomas: 2

7. Leadership role in the experiment

Spokeperson and Chairman of the Executive Committee (A. Zichichi), Chairman of the Analysis Committee (P. Galeotti), Chairman of the Technical Committee (P. Giusti).

8. Innovative instruments

The LVD collaboration has set up in the Gran Sasso Laboratory a plant for the production of the good quality and inexpensive liquid scintillator needed for the experiment. Nowadays it is used to develop new liquid scintillators with improved characteristics by using various dopants.

9. Competing experiments

Relative to the detection of low energy neutrino bursts, the main competing experiments are SuperKamiokande, SNO, AMANDA and, until the end of 2000, MACRO. LVD compares well with respect to these experiment due to its following characteristics.

- LVD can operate with a lower neutrino energy threshold than the experiments based on Cerenkov light detection (SuperKamiokande, SNO, AMANDA). This is an important characteristics to be able to study objects emitting at low temperature n-sphere. Moreover, the lower energy threshold should allow for the observation of the low energy neutrino burst emitted, according to some models, when a star collapses into a black hole.

- LVD can identify with high efficiency the dominant reaction (anti-n e p --> e+ n) detecting the delayed g emitted in the neutron capture, and not simply by the lack of directionality as for light water Cerenkov detectors. Therefore LVD can measure a clean anti-n e energy spectrum and separate the rare but very interesting charged and neutral current interactions with Carbon nuclei .

- The modularity of the LVD apparatus allows for good calibration and maintenance of the detector without loosing live time at the expense of a small reduction of the active detector mass. In the last years LVD has been watching for stellar collapses in the Galaxy with an average duty cycle greater than 99%.

10. International Committee which has reviewed the experiment.

The LVD experiment has been reviewed and approved by the LNGS International Scientific Committee.