V. N. Grishin

Precision measurement of energy and position resolutions of the BTeV electromagnetic calorimeter prototype

Abstract The energy dependence of the energy and position resolutions of the electromagnetic calorimeter prototype made of lead tungstate crystals produced in Bogoroditsk (Russia) and Shanghai (China) is presented. These measurements were carried out at the Protvino accelerator using a 1– 45 GeV electron beam. The crystals were coupled to photomultiplier tubes. The dependence of energy and position resolutions on different factors as well as the measured electromagnetic shower lateral profile are presented.

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.

Study of the compensated lead hadron calorimeter on hadron, electron and lead–ion beams

Abstract The results of tests on a compensated lead hadron calorimeter with cell size 10×10xa0cm 2 , thickness 8 nuclear interaction lengths and sampling of 16xa0mm lead, 4xa0mm scintillator, with hadron, electron and lead–ion beams up to 32xa0TeV total energy are presented. The hadronic energy resolution of the calorimeter is 57%/ E , the nonuniformity is better than 10% and the measured ratio e / h =1.01. Five hundred cells of this calorimeter have been made for experiments at CERN and IHEP, Protvino.

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.

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

Single-spin asymmetry of inclusive π0-meson production in 40-GeV pion interactions with a polarized target in the target-fragmentation region

Data on the single-spin asymmetry (AN) of inclusive π0 production in 40-GeV pion interactions with a polarized target, π−+↑→π0+X, are presented for the target-fragmentation region. The result is AN=(−13.8±3.8)% for −0.8<xF<−0.4 and 1<pT<2 GeV/c and is compatible with zero for −0.4<xF<−0.1 and 0.5<pT<1.5 GeV/c. At a π0 momentum of about 1.7 GeV/c in the c.m. frame, the asymmetry becomes nonzero both in the central and in the target-fragmentation region. The behavior of the asymmetry is similar to that observed in the beam-fragmentation region of the E-704 (FNAL, 200 GeV) and STAR (BNL, 20 TeV) experiments, which employed a polarized proton beam.

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.

Analyzing Power in the Reaction p + p └ → π 0 + X in the polarized-target fragmentation region at an energy of 50 GeV

The results obtained by measuring, at the U-70 accelerator in Protvino, the single-spin asymmetry AN in the reaction p + p└ → π0 + X at a beam energy of 50 GeV in the Feynman variable range of −0.6 < xF < −0.1 are presented. The asymmetry AN is close to zero at small |xF| and grows in magnitude with |xF|, reaching 6.4% in the region of |xF| > 0.25. The results of these measurements agree with data of the E704 experiment on the asymmetry of π0 mesons at the Fermi National Accelerator Laboratory in the region of polarized-beam fragmentation and with the results of measurements in the region of polarized-target fragmentation that were performed in Protvino by using a 40-GeV π−-meson beam and a 70-GeV proton beam.

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.