at 109-1010 torr. Cryogénie reliability was more than 98%, and it is hoped that cooling time will eventually be Liquid Scintillator Neutrino Detector (LSND) halved. Magnets were fed by a 90A direct current. A 5 MeV/nucleon deuteron Access. Door beam was injected and first full turns were achieved on 26 March. The high frequency accelerating System was tested for 12 hours under 8kV at 0.6 MHz. The next stage is a run at 1.5kA with limited beam accélération and irradiation of internai targets. 2000 hours are scheduled this year for Nuclotron commissioning. Meanwhile slow extraction System assembly continues, en route to installation in the ring next year. The commissioning of this pioneer machine is a major scientific and technological achievement for the Laboratory and carries an important message for the development of (Above) Schematic of the LSND detector at research capabilities in JINR coun- LAMPF, Los Alamos, designed to search for neutrino oscillations with high sensitivity and to LOS ALAMOS tries. measure the strange quark contribution to the proton spin in neutrino-proton elastic scatter- New neutrino ing. The tank, approximately 6m in diameter (Below) At Dubna's superconducting Nuclotron and 9m long, is covered by 1220 8" experiment heavy ion machine, the SPHERE electromag phototubes and will be filled with 2001 of dilute netic calorimeter is prepared for studies on liquid scintillator (see front cover). internai targets. The Liquid Scintillator Neutrino Detector (LSND) experiment at Los Alamos5 Meson Physics Facility (LAMPF) has been designed for a high sensitivity search for oscillations between muon- and electron-type neutrinos and, concurrently, between the corresponding antineutrinos. In addition, the experiment will measure neutrino-proton elastic scattering, thereby determining the strange quark contribution to the proton spin. At low momentum transfer, neutrino-proton elastic scattering is a direct probe of this contribution. The detector tank, filled with 200 tons of dilute liquid scintillator, has 1220 8" Hamamatsu photomultiplier tubes mounted on the inside, cover-
10 CERN Courier, July/August 1993 256-Channel readout Hamamatsu's Multi-Anode PMTs with 256-channel readout not only dramatically extend the conditions for SCIFI tracking and calorimeter measurement, they operate with 2 percent or less crosstalk. This ensures high performance and reliability in addition to décisive SCIFI readout. For detailed information on 256- Channel Multi-Anode PMTs, just contact Hamamatsu Photonics at the office nearest you.
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U.S.A.: Hamamatsu Corporation, tel: 1-908-231-0960 FAX:1-908-231-1218 North Europe: Hamamatsu Photonics Norden AB. TEL: 46-8-59032190 FAX: 46-8-59094567 Germany: Hamamatsu Photonics Deutschland GmbH, tel: 49-8152-3750 fax:49-8i52-2658 Italy: Hamamatsu Photonics Italia S.R.L. TEL: 39-(02) 935 81 733 FAX: 39-(02) 935 81741 France: Hamamatsu Photonics France S.A.R.L. tel: 33-(i) 49 75 56 80 fax: 33-(i) 49 75 56 87 Spain: Hamamatsu Photonics Espana S.L. tel: 34-3 699 65 53 FAX: 34-3 588 19 66 United Kingdom: Hamamatsu Photonics UK Limited, tel: 44-81-367-3560 FAX: 44-81-367-6384
13b Circle advertisement number on reader service form ing 25% of the surface area. The tron-proton elastic scattering at 350 dilute liquid scintillator is a mixture of TRIUMF MeV. A 2.5 microamp polarized minerai oil and 0.03 g/1 of b-PBD, so proton beam on a liquid deuterium that Cherenkov and scintillation light Record polarized target in a phase-restricted cyclotron will be detected in an approximate beams mode reduced the time-spread of the ratio of 1 to 4. The atténuation length incident proton beam to less then 0.8 of the scintillator is greater than 30 m ns. for wavelengths above 425 nm. At the TRIUMF cyclotron Laboratory The current was limited by the in Vancouver, the Optically Pumped After two years of data collection for cooling capabilities of the liquid Polarized négative hydrogen Ion (anti)neutrino mixing, the upper limits deuterium target cryostat. Polarized Source (OPPIS - December 1991, on the square of the mass différence neutrons emerged via the D(p,n)2p 2 2 page 10) is underlining the potential will be 1.7 x10 ev for maximal reaction at an angle of 9°. Beam 2 of thèse techniques for spin physics. mixing for antineutrinos and 4.0 x 10 intensity at the expérimental target for neutrinos. Similarly, mixing The source is performing well, (12.5 m from the liquid deuterium strengths of 2.7 x 104 can be probed producing a 20 microamp d.c. beam target) is uniform over an area 75 for each channel for ail squared with a proton polarization above 80% mm wide by 62 mm high, with a mass différences above 1eV2. and with good reliability. Spin re neutron flux of 0.9 x 105 microamps versai has also been speeded up and This will provide the best terrestrial per sq cm per s and a polarization of its effect on the beam intensity limits on oscillations between muon- 65-70%. At the same time, about 0.2 demonstrated to be negligible. and electron-type neutrinos. In microamps of polarized beam are addition, the neutrino-proton elastic- This substantially boosts TRIUMF's extracted from the cyclotron into a scattering reaction rate will be meas- capabilities for polarization experi separate beamline for other experi ured to an accuracy of 10, determin- ments. Data-taking has recently ments. ing the strange quark contribution to been completed for a second-gen- The new source is also being used the proton spin to within ±0.05. eration experiment measuring to study parity violation in proton- charge-symmetry breaking in neu Other physics goals include meas- urements of the charged current reactions where the neutrinos pro duce électrons or muons, the inelas- tic neutral current reaction where the neutrino stays a neutrino but excites the target, and a search for the 'rare' decays of a neutral pion and an eta into a neutrino-antineutrino pair. The LSND collaboration includes groups from California at Riverside, Santa Barbara and San Diego, the
University of California Intercampus The TRIUMF optically pumped polarized Institute for Research at Particle ion source delivers hf ions of typîcally Accelerators, Embry-Riddle Aeronau- 80% polarization. tical University, Linfield Collège, Los Alamos, Louisiana State, Louisiana Tech, New Mexico, Pennsylvania, Southern, and Temple. Data collec tion begins this summer. Target (Protons)
Schematic of the OPPIS optically pumped Neutron j polarized proton source at the Canadian Detector TRIUMF Laboratory, now delivering 80% Bank/ Neutron Polarîmeter polarization.
12 CERN Courier, July/August 1993