A.A. Nozdrin

Performance of a prototype tracking detector for double beta decay measurements

Abstract To investigate double beta decay processes, the NEMO collaboration began a long-range research and development program in 1988. The NEMO 2 detector, which is now running in the Frejus underground laboratory (L.S.M. Laboratoire Souterrain de Modane), is the second prototype. It consists of a 1 m2 source foil sandwiched between Geiger cell drift chambers for electron tracking and two plastic scintillator walls for energy and time-of-flight measurements. The technical description of the detector is followed by the study of the various sources of background.

The OPERA experiment Target Tracker

The main task of the Target Tracker detector of the long baseline neutrino oscillation OPERA experiment is to locate in which of the target elementary constituents, the lead/emulsion bricks, the neutrino interactions have occurred and also to give calorimetric information about each event. The technology used consists in walls of two planes of plastic scintillator strips, one per transverse direction. Wavelength shifting fibres collect the light signal emitted by the scintillator strips and guide it to both ends where it is read by multi-anode photomultiplier tubes. All the elements used in the construction of this detector and its main characteristics are described.

Measurement and control of the 214Bi contamination in the ββ NEMO-2 experiment

Abstract In the double beta decay (ββ) experiment NEMO-2, the 214 Bi radioactivity has been measured as background for the ββ processes. The analysis of the 214 Bi contamination has been performed via the signature of 214 Po alpha decay. This method has been applied to data taken with enriched 100 Mo and 116 Cd sources. At the level of NEMO-2s sensitivity, in a 1.0 mole yr study of enriched material, the contamination of the sources can be measured in the range of 2.0 mBq kg −1 . The effects of deposited contamination by 222 Rn are also discussed and estimated at the level of 0.3 mBq per square meter of source foil. Backgrounds for neutrinoless double beta decay (ββ0v) are deduced from these measurements and the consequences for the higher sensitivity ββ experiment NEMO-3 are drawn.

Scintillation hodoscopes for time-of-flight measurements

Abstract The performances of the TOF scintillation counters used in the SIGMA-AIAKS spectrometer are presented. The counters, made of NE110, are 150, 65 and 10 cm long, 10 cm wide and 1.5 cm thick. The time resolutions for minimum ionizing particles have been measured to be σ t = 0.18 ns, 0.14 ns and 0.11 ns respectively. The main contribution to the resolution is given by the photoe collection statistics determined by the decay time of the scintillator and the difference of the optical paths in the counter. The scintillation counters, assembled into hodoscopes of 1.5 × 3.2 m 2 and 0.65 × 0.8 m 2 are used for identification of particles through the TOF. The algorithms of off-line data processing are also presented.

Fe-scintillator hodoscopic hadron calorimeter

Abstract A Fe-scintillator hodoscopic hadron calorimeter is described. It consists of independent sections, each containing four total absorption counters 20×20 cm 2 in cross section. The energy resolution for hadrons in the energy range E = 4–40 GeV is σ E / E = 0.02 + 0.52/√ E and the mean space resolution is ∼ 2 cm at 40 GeV.

Cross sections of backward proton production in 40 GeV/c π−(K−,p)−A interactions

Abstract The inclusive cross sections of backward proton production in π − ( K − , p ) -Be, Al, Cu, Pb interactions at 40 GeV/ c are presented. Protons have been detected in the angular range 150°–165° and kinetic energy region 0.1–0.3 GeV. The invariant cross-section ratios for various beam particles are independent of the values of kinetic energy and of the nuclear target type: 〈ƒ K − /ƒ π − 〉= 0.87 ± 0.03 stat ± 0.03 syst , 〈ƒ p /ƒ π − 〉 = 1.82 ± 0.10 stat ± 0.05 syst . The A -dependence of the cross-section slope parameter for A ⩾27 is less than ∼2%.

Experimental Study of the Radiative Scattering π-p → π-pγ at 43 GeV

The pion radiative scattering (π-p → π-pγ) has been studied at 43 GeV in the interval 0.2 < |tp| < 0.4 (GeV/c)2 of the momentum transfer squared to the proton and in the range of photon energy 2 < ω < 40 GeV. Calculations based on Low theorem agree well with measured ω, tp and mπγ (final πγ-invariant mass) differential cross-sections. The results obtained extend the validity of Low approach to the radiative scattering at high energies.