N. G. Minaev

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.

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.

Measurement of the single-spin asymmetry in the reaction π−d↑ → π0X in the beam-fragmentation region at 40 GeV and pT of up to 2 GeV/c

The single-spin asymmetry AN in the reaction π− + d↑ → π0 + X in the beam-fragmentation region at the energy of 40 GeV was investigated by using the PROZA setup installed at the U-70 accelerator of the Institute for High Energy Physics (IHEP, Protvino). It was measured to be AN = (13.6 ± 2.6(stat.) ± 2.0(syst.))% in the intervals 0.7 < xF < 1.0 and 1.0 < pT < 1.8 GeV/c. The results agree with the asymmetry of π0 mesons in the charge-exchange reaction π− + p↑ → π0 + n at the same values of the transverse momentum and beam energy. The asymmetry in the reaction K− + d↑ → π0 + X was simultaneously measured and found to be AN = (11 ± 14)% for pT > 1.2 GeV/c.

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.

Methods of Coordinate Reconstruction in Gaseous Detectors with Cathode Readout

The methods for reconstructing the coordinates of charged particles in gaseous detectors with cathode readout are analyzed in detail. The spatial resolution is investigated using spatial-reconstruction procedures based on the known relations and the new formulas proposed in the paper. The use of this method is illustrated by processing the beam-test data of the charged-particle veto detector of the proton spectrometer for the ALICE experiment at the Large Hadron Collider (CERN). The spatial resolution of the detector based on the multiwire proportional chamber with cathode-pad readout (pad dimensions are 22 × 10.7 mm, the anode-wire pitch is 5.65 mm, and the anode–cathode gap is 5.5 mm), measured along and across the anode wires, is σx ≅ 0.14 cm and σy ≅ 0.15 cm, respectively.

A Charged-Particle Detector Based on Proportional Tubes with a Segmented Cathode and Cathode Readout

A charged-particle detector based on proportional tubes with cathode readout is described. The cathode is sectionalized into 2.2 × 2.2-cm pads. The detector was tested on high-energy particle beams. At an anode-to-cathode distance of 1.1 cm, the spatial resolution was 1.25 mm along the anode wire. A simulation model of the detector on the basis of the measured pad-response function was proposed, compared to the experimental data, and used to calculate the two-track resolution. The detector can be used in various experiments as a large-area multiparticle two-coordinate detector.

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.

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.