Charged particle (π-K) separation in the momentum range 0.5-0.7 GeV/c using a new method of shape analysis of the signal from a liquid krypton (LKr) ionization chamber has been experimentally studied. The detector has been exposed to pions and protons at the T11 test beam at the CERN PS. The shape of the preamplifier output signal was recorded by a waveform digitizer, then it was doubly “differentiated” in order to obtain few dE/dχ measurements inside a 2 cm LKr gap. Results on particle separation at three different energies are presented.

The SIGMA-AYAKS setup was used to study the production of cumulative protons p(B), having kinetic energies in the range 0.1 < T(B) < 0.3 GeV and accompanied by fast rho0 mesons with the Feynman variable x(F) > 0.6 and squared transverse momentum p(t)2 < 1 (Ge V/v)2, in pion-nucleus interactions at the incident pi--meson momentum p(BM) = 40 GeV/c. In pi-Be interactions, the T(B)-dependence of the invariant cross section of cumulative. proton production is measured. The polarization properties and distributions of fast rho0 mesons over x(F) and p(l)2 are also studied. It is found that characteristics of rho0 mesons in the distinguished channel of the reaction are similar to those of rho0 mesons produced in the beam fragmentation range of pi-N interactions.

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: 〈ƒK−/ƒπ−〉= 0.87 ± 0.03stat ± 0.03syst, 〈ƒp/ƒπ−〉 = 1.82 ± 0.10stat ± 0.05syst. The A-dependence of the cross-section slope parameter for A⩾27 is less than ∼2%.

The results of an experiment to search for dibaryon resonances in processes with cumulative protons in pi-Be interactions at 40 GeV/c are presented. For the mass range 2.5-4.1 GeV/c2 bounds of 10.7-20.3-mu-b are obtained on the cross section for production of dibaryon resonances decaying into a proton pair.

The results of an experimental search for dibaryon resonances in the target fragmentation region in the mass range 2.5-4.1 GeV/c2 in pi-Be interactions at the momentum 43 GeV/c are presented. Bounds of 0.5-12.6-mu-b are obtained on the cross section for production of dibaryon resonances which decay into a proton pair.

The procedure and results of mass testing of plastic streamer tubes for the DELPHI hadron calorimeter are described in detail. The mass testing includes three stages: high voltage test and conditioning, X-ray test on radiation load capability and wire tension control in ready detectors. The productivity of the test workshop was 240 detectors per day at maximum. After testing of about 25 000 streamer tubes, 8% have been rejected on the ground of severe rejection criteria which exceed significantly the working conditions in the DELPHI experiment.

The results of measurement of the inclusive cross sections for production of cumulative protons in pi- (K -,pBAR) Be, Al, Cu, Pb interactions at 40 GeV/c are presented. Protons were detected in the angular range 150-165-degrees and in the kinetic-energy range 0.1-0.3 GeV. The ratios of the invariant cross sections for various types of beam particles do not depend on the kinetic energy or on the type of nucleus: = 0.87 +/- 0.03stat +/- 0.03syst, and = 1.82 +/- 0.10stat +/- 0.05syst. No dependence on A was observed for the slope parameter of the cross sections at a level of about 2% for A greater-than-or-equal-to 27. An increase of the ratios of the cross sections, f(A) (A)/f(A) (Be), at values of the cumulative number x(K) > 2 can be considered as an indication that the probabilities of production in light and heavy nuclei of objects with a mass exceeding two-nucleon masses are different.

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 σt = 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 m2 and 0.65 × 0.8 m2 are used for identification of particles through the TOF. The algorithms of off-line data processing are also presented.

In the reaction of π- dissociation into a μ+μ-π- system on a Cu nucleus, a clear enhancement in the ρ0π- effective-mass distribution has been observed in the π2(1680) region. Partial-wave analysis shows that this enhancement is due to the P-wave and has a resonant nature. Coherent and incoherent cross-sections for this enhancement have been measured.

The vertex \ensuremath{\gamma}\ensuremath{\rightarrow}3\ensuremath{\pi} has been investigated in the reaction of pion pair production by pions in the nuclear Coulomb field, ${\ensuremath{\pi}}^{\ensuremath{-}}$+(Z,A)\ensuremath{\rightarrow}${\ensuremath{\pi}}^{\ensuremath{-}}$+${\ensuremath{\pi}}^{0}$+(Z,A), in the region of low-invariant-mass ${\ensuremath{\pi}}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\pi}}^{0}$ pairs. The experiment has been carried out in the 40-GeV pion beam of the IHEP accelerator (Serpukhov) with the SIGMA spectrometer. We have measured for the first time the cross section of the reaction in the region of momentum transfer squared ${q}^{2}$2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$ (GeV/c${)}^{2}$, \ensuremath{\sigma}/${Z}^{2}$=1.63\ifmmode\pm\else\textpm\fi{}0.23\ifmmode\pm\else\textpm\fi{}0.13 nb, and the \ensuremath{\gamma}\ensuremath{\rightarrow}3\ensuremath{\pi} coupling constant ${F}^{3\ensuremath{\pi}}$=12.9\ifmmode\pm\else\textpm\fi{}0.9\ifmmode\pm\else\textpm\fi{}0.5 ${\mathrm{GeV}}^{\mathrm{\ensuremath{-}}3}$, where the first (second) error is statistical (systematic). The obtained result agrees with the calculations based on the Wess-Zumino-Witten effective Lagrangian. The hypothesis of chiral anomalies and the color-SU(3) quark symmetry are confirmed.

The method for readout of information from a wire chamber through a conventional conductive wire cathode is tested to study the possibility of its practical usage. It is observed that the value of the signal induced on an external readout electrode depends on the detector geometry and makes up approximately 5–10% of the anode signal value. The application of this method should permit one to separate a detector into an active device and an independent readout system as well as to make the readout system more flexible and to improve detector coordinate properties.

Streamer tubes of two kinds — with and without conductive cover — were investigated. Their main characteristics were measured. It was observed that the induced signal distribution over the tube surface practically depends neither on the readout side, nor on the kind of the tube.

Plastic scintillation counters have been used in a search for the axion in the IBR-2 pulsed reactor. No gamma pairs were detected outside the reactor shielding, in contradiction of Faissner's data, which show the observation of an axion at a reactor in Juelich, but in support of the conclusion by Zehnder et al. that the ''standard axion'' does not occur in nature.