[en] A prototype gamma ray detector for the detection of π⁰ in the proposed experiment at SPring-8 to study the Gerasimov-Drell-Hearn (GDH) sum rule (GDH experiment) has been built and tested. The detector is fabricated with lead-scintillator tiles and wave length shifter fiber readout. This detector will be placed inside the bore of the superconducting magnet which supplies the polarized target with a 2.5 T magnetic field. High-detection efficiency (above 85%) for the gamma rays is the most important requirement for this detector to be employed in the proposed experiment. It has been tested with minimum ionizing particles, electrons and gamma rays. The results of the tests in comparison with some Monte Carlo simulations are presented. The evaluated efficiency for gamma rays ranging in energy above 50 MeV is higher than 90%

[en] The performance of scintillating fiber detectors with 2 m long light guides was investigated for COMPASS experiment, using a 450 MeV/c electron beam.Prototypes consisting of 0.5 mm diameter fibers (Kuraray SCSF-38 single-cladding) with the position-sensitive photomultipliers H6568 (Hamamatsu) were constructed for the test. The time resolution of σ∼430 ps was obtained with about 10 photoelectrons for the prototype of 10-layers structure. (author)

[en] A prototype of a scintillating fiber hodoscope was constructed with multi-cladding scintillating fibers and a multi anode photomultiplier (H6568, HAMAMTSU). The hodoscope has a seven structure of a scintillating fiber with 0.5 mm in diameter and stacked in closest packing in order to improve its efficiency and time resolution. The hodoscope has been tested using a proton beam. The time resolution of about 700 ps in FWHM has been obtained

[en] A new frozen-spin target has been developed, that allows the detection of emitted particles in an angular acceptance of almost 4π in the laboratory frame. The central part of this new target represents a ³He/⁴He dilution refrigerator that is installed horizontally along the beam axis. The refrigerator includes an internal superconducting holding coil to maintain the nucleon polarization in the frozen-spin mode longitudinally to the beam. The design of the dilution refrigerator and the use of an internal holding coil enabled for the first time the measurement of a spin-dependent total cross section in combination with a polarized solid state target. This new frozen-spin target was used successfully to measure the helicity asymmetry of the total photoabsorption cross-section at the Mainz accelerator facility MAMI. This experiment has been performed in order to verify for the first time the GDH sum rule

[en] A study of spin effects at fragmentation of 9 GeV polarized deuterons into high momentum pions d-barA → π (θ) X was for the first time performed at Dubna polarized deuteron facility. Large D-state effects were observed at fragmentation of tensor polarized deuterons into cumulative pions at non-zero emission angles

[en] Our group is constructing a polarized deuteron target system for a measurement of D-vector(d-vector),p)T reaction at low energies. If we assume that the incident energy of deuteron beam is 20 MeV, and its intensity is 1 nA, required specifications to the target system are the polarization is larger than 40%, the target thickness is ∼1 mg/cm2, a cooling power of refrigerator is several mW at 200 mK. At present, the lowest temperature of 200 mK and the cooling power of 2.6 mW at 500 mK was achieved. On the other hand, the development of target material has been made. The polarization of 17% was obtained to a electron irradiated--CD₂ foil with a doze of 1x10¹⁶ e^-/cm²

[en] The GeV photon beam at SPring-8 is produced by backward-Compton scattering of laser photons from 8 GeV electrons. The maximum energy of the photon will be above 3 GeV, and the beam intensity will be 10⁷ photons/sec. Polarization of the photon beam will be 100 % at the maximum energy with fully polarized laser photons. We report the outline of the quark nuclear physics project with this high-quality high-intensity beam

[en] Tensor analyzing power T₂₀ in d-vectorA→π(θ=0 deg. )X has been measured at fragmentation of 9 GeV deuterons into pions with the momenta from 3.5 to 5.3 GeV/c at H-, Be-, and C-targets. This momentum range corresponds to region of cumulative pion production where the deuteron core structure up to r≅0.4 fm is probed. The values of T₂₀ are found to be small and positive in contradiction with the Impulse Approximation calculations assuming a direct mechanism of pion production on high momentum nucleon in the deuteron (NN→NNπ). In this report we present new data on tensor Ayy analyzing powers at non-zero angles (θ=135,180mr) with pion transverse momenta up to P_t=0.8 GeV/c. Ayy increases with rise of P_t in the cumulative region reaching the magnitude of -0.4 at P_t=0.7-0.8 GeV/c

[en] Tensor analyzing power T₂₀ of the reaction d-vectorA→π(0 deg.)X was measured in the fragmentation of 9 GeV deuterons into points with the momenta from 3.5 to 5.3 GeV/c at hydrogen, beryllium and carbon targets. This momentum range corresponds to region of cumulative pion production The values of T₂₀ are found to be small and consistent with positive values in contradiction with the Impulse Approximation calculations based on assuming a direct mechanism of pion production (NN→NNπ). New data on tensor Ayy analyzing power for pion production at the non-zero angle (θ_π=135,180mr) with pion transverse momenta up to P_t=0.8 GeV/c are presented. Ayy increases with rise of P_t in the cumulative region

[en] The helicity dependence of the total cross section for the γ→p→→nπ⁺π⁰ reaction has been measured for the first time at incident photon energies from 400 to 800 MeV. The measurement was performed with the large acceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator in Mainz. This channel is found to be excited predominantly when the photon and proton have a parallel spin orientation, due to the intermediate production of the D₁₃ resonance