Peter Kozma

Radiation resistivity of large tungstate crystals

Abstract Radiation resistivity of large tungstate crystals PbWO4 and CdWO4 has been studied for doses up to 105 Gy. Radiation resistivity was examined by the measurement of optical transmission through tungstate crystals before and after gamma-ray irradiations. The absolute degradation of transmission for 105 Gy dose at the wavelength of the peak emission of both tungstate crystals PbWO4 and CdWO4 were found to be lower than 12.5 and 8.0%, respectively. The complete recovery of radiation damage was observed 15 days after irradiations.

Radiation resistivity of large CeF3 crystals

Radiation damage of a 3 × 3 × 6 cm3 CeF3 crystal has been measured for doses up to 105 Gy. The degradation of transmission for this dos

A barium fluoride scintillator working with p-p′ diphenylstilbene wavelength shifter

Abstract The energy and time resolutions of a 3.2×3.2×1.0 cm 3 BaF 2 scintillator coated with a thin layer of diphenylstilbene wavelength shifter have been measured in comparison to a pure BaF crystal of the same dimensions. The p-p′ diphenylstilbene was shown to be an efficient shifter of the ultraviolet light with a slightly better energy resolution. The time resolution measured for Co gamma-rays was degraded from 190 to 360 ps.

A cerium fluoride scintillator coupled to a FEU-140 photomultiplier☆

Abstract A large CeF 3 scintillation crystal coupled to a FEU-140 PMT was tested with gamma-ray sources. A good energy resolution as well as uniformity of the light output along the length of the crystal are demonstrated.

Tests of large BaF2 crystals in beams of relativistic particles

Large modules of BaF2 crystals were tested with gamma sources and in beams of relativistic particles accelerated at the Dubna synchrophasotron. The energy resolution and the timing characteristics of BaF2 crystals depend on the strobe signals. A good uniformity of the light output along the whole length of the crystals when irradiated with relativistic particles and gamma-rays has been demonstrated.

Comparison of properties of large BaF2 and BaF2 + DPS scintillators

Abstract The energy and time resolution of large barium fluoride with p-p′ diphenylstilbene wavelength shifter have been measured in comparison to a pure barium fluoride crystal of the same dimensions. The energy resolution for barium fluoride + DPS was found to be slightly poorer than that of the pure barium fluoride crystal. The time resolution measured for gamma-ray coincidences ( 60 Co, energy threshold 1 MeV) was degraded from 245 to 490 ps.

Diphenylstilbene as a wavelength shifter

Abstract Thin diphenylstilbene layers deposited on glass were shown to be an effective wavelength shifter of He-scintillation into a spectral region where conventional photomultiplier tubes are sensitive.

The behaviour of thin deuterated-polyethylene targets enclosed in gold layers

Abstract Deuterated-polyethylene targets with thicknesses of 0.5 mg cm−2 were bombarded with 1 MeV deuterons in order to estimate the deuterium deterioration. The (CD2)n foils enclosed in gold layers were shown to be suitable targets for the d + d reaction experiments in the low energy region.

Photomultiplier sensitivity improvement by using wavelength shifters

Abstract Photomultiplier quantum sensitivity in the UV region of the photomultipliers FEU-85, FEU-130 and FEU-140 can be improved by a wave-shifter covering. The best results were obtained for PMMA-polymethylmetacrylate and P-P′ diphenylstilbene wavelength shifters.

Cross sections for the production of 11C in C targets by 3.65 A GeV projectiles

Abstract The absolute cross sections for the production of 11 C in C targets by 3.65 A GeV protons, deuterons, 4 He- and 12 C-ions were measured. Annihilation radiation from 11 C was counted using a large-volume Nal(Tl), and a BaF 2 detector. The flux measurement technique, based on registration of charged particles by means of a thin nuclear emulsion layer rotating in a beam, as well as a fission chamber, was used. The results are compared with earlier measurements of the cross sections in carbon targets using high-energy projectiles, and with Glauher theoretical predictions as well.