A. M. Davidenko

Study of radiation damage in lead tungstate crystals using intense high-energy beams

We report on the effects of radiation on the light output of lead tungstate crystals. The crystals were irradiated by pure, intense high-energy electron and hadron beams as well as by a mixture of hadrons, neutrons and gammas. The crystals were manufactured in Bogoroditsk, Apatity (both Russia), and Shanghai (China). These studies were carried out at the 70-GeV proton accelerator in Protvino.

Design and performance of LED calibration system prototype for the lead tungstate crystal calorimeter

A highly stable monitoring system based on blue and red light emitting diodes coupled to a distribution network comprised of optical fibers has been developed for an electromagnetic calorimeter that uses lead tungstate crystals readout with photomultiplier tubes. We report of the system prototype design and on the results of laboratory tests. Stability better than 0.1% (r.m.s.) has been achieved during one week of prototype operation.

Preparation of new polarization experiment SPASCHARM at IHEP

A new experiment SPASCHARM devoted to a systematic study of polarization phenomena in hadron-hadron interactions in the energy range 10-70 GeV is under preparation at IHEP (Protvino). The physical observables will be single-spin asymmetries, hyperon polarizations and spin-density matrix elements. A universal setup will detect and identify various neutral and charge particles in the full azimuthal angle and a wide polar angle range. A polarized target is used to measure the SSA. The SPASCHARM sub-detectors are being designed and constructed now. The possibility of obtaining a polarized proton beam for the SPASCHARM experiment from Lambda decays is under study.

Effect of γ Irradiation on the Scintillation and Optical Properties of Lead Tungstate Crystals

The radiation hardness of a test batch of lead tungstate crystals grown by a new technology at the Bogoroditsk Technochemical Plant for the PANDA experiment has been measured. The optical properties of the crystals have been investigated at temperatures ranging from +20 to −20°C under irradiation with a 137Cs radionuclide source. The light yield in the crystal is seen to considerably increase with a decrease in its temperature. In addition, the loss of the crystal transparency under irradiation at low temperatures is higher than under irradiation at room temperature. As a result, at a fixed dose rate, the signal from the crystal at a negative temperature may be considerably greater than the signal at room temperature even if the accumulated dose is high.

Single-spin asymmetry of inclusive neutral-pion production in pp∩ interactions at 70 GeV in the region -0.4 < xf < -0.1

For the kinematical region specified by the inequalities −0.4 < xF < −0.1 and 0.9 < pT < 2.5 GeV/c, the results are presented that were obtained by experimentally determining the single-spin asymmetry of inclusive neutral-pion production in the reaction p + p↑ → π0 + X at 70 GeV. According to these results, the asymmetry is close to zero in the region −0.2 < xF < −0.1 and grows in magnitude with decreasing xF, amounting to (−10.6 ± 3.2)% for −0.4

Searches for single-spin asymmetry in the inclusive production of neutral pions in the central region at a proton beam energy of 70-GeV

Results are presented that were obtained by measuring single-spin asymmetry in the inclusive production of neutral pions in the reaction p+p ↑→ π0+X at xF≈0. A beam of 70-GeV protons was extracted directly from the vacuum chamber of the accelerator by means of a bent single crystal. For transverse momenta in the range 1.0<pT<3.0 GeV/c, the single-spin asymmetry independently measured by two detectors is zero within the errors. This result is in agreement with Fermilab data obtained at 200 GeV, but it is at odds with CERN data measured at 24 GeV.

Studying the radiation hardness of lead tungstate crystals under long-term γ irradiation

Changes in the transparency of lead tungstate crystals under continuous ∼1200-h irradiation with γ rays of a radionuclide 60Co source were investigated. The crystal temperature was maintained at a level of −15°C at a dose rate of 0.1 Gy/h. The crystal transparency recovery process was investigated after the irradiation at temperatures varying from −15 to +38°C. The study was performed while preparing for the PANDA experiment in the FAIR project in Germany.

Spin Physics Program At IHEP-Protvino

A new single‐spin asymmetry AN measurement has been carried out at IHEP at 50 GeV. AN was found to be −(6.2±1.5)% in the polarized target fragmentation region at −0.6<xF<−0.25. The result proves that asymmetry does not depend on beam energy. A review of polarization results from Protvino as well as a proposal of the new experiment SPASCHARM are also presented.

AN AT SMALL NEGATIVE VALUES OF xF IN THE REACTION p + p↑ → π0 + X AT 70 GeV AND UNIVERSAL THRESHOLD IN INCLUSIVE PION PRODUCTION

The talk continues the series of Single Spin Asymmetry (SSA)

Single spin asymmetry measurements for

\pi^0