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PANDA is a challenging experimental setup to be implemented at the high-energy storage ring (HESR) at the international facility FAIR, GSI (Germany). PANDA physics program relies heavily on the capability to measure photons with excellent energy, position and timing resolution. For this purpose PANDA proposed to employ electromagnetic calorimeters using two different technologies: compact crystal calorimeter cooled to - 25 ∘ C around target and lead–scintillator sandwich calorimeter with optical fibers light collection (so-called shashlyk calorimeter) in the forward region. Institute for High Energy Physics (IHEP) PANDA group reports on two types of measurements performed at IHEP, Protvino: radiation hardness of the PWO crystals at - 25 ∘ C and testbeam studies of the energy and position resolution of the shashlyk calorimeter prototype in the energy range up to 19 GeV.

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., 10 pages, 6 figures, LaTeX2e

BTeV is a new dedicated B-physics project at Fermilab. It requires excellent photon detection which is crucial to study CP violations in B decays and rare decays of B's to explore physics beyond the standard model. Electromagnetic calorimeter (EMCAL) built of lead tungstate (PbWO4) scintillating crystals can provide excellent energy and position resolution, compact shower size, fast signal, and reasonable radiation hardness. We have carried out beam studies of a prototype of the BTeV electromagnetic calorimeter. The test took place at the Institute for High Energy Physics, Protvino, Russia. The prototype was built of 25 PbWO4 crystals, from russian and chinese manufacturers. The results of the first set of measurements have confirmed the expected good energy and position resolution of the prototype, though revealed the fact that PbWO4 was not as radiation hard as expected when irradiated with intense high energy hadron and electron beams. The next step included additional studies of radiation hardness, methods of monitoring changes of crystal signal due to radiation using LEDs with different wavelength, and possible procedures for testing PbWO4 radiation hardness without high energy beams.

We employed two independent methods to study possible damage to the scintillation mechanism in lead tungstate crystals due to irradiation by a 34 V pion beam. Firstly 10 crystals were irradiated simultaneously over 30 h by a narrow beam, so that only a small region of each crystal was affected. We studied the effect of the irradiation on the light output non-uniformity. If a localized degradation was observed, it would indicate damage to the scintillation mechanism. Secondly, we detected light output using two phototubes attached to the sides of a crystal. Since these phototubes detect scintillation light only from a small localized region, the effect of transmission loss should be minimal. We did not see any statistically significant evidence for scintillation mechanism damage with either method. The effect is consistent with zero, and the upper limit is 0.5% at 95% C.L.

We report on the performance of a monitoring system for a prototype calorimeter for the BTeV experiment that uses Lead Tungstate crystals coupled with photomultiplier tubes. The tests were carried out at the 70 GeV accelerator complex at Protvino, Russia., Comment: 12 pages, 8 figures, LaTeX2e, revised version

A beam line for electrons with energies in the range of 1 to 45 GeV, low contamination of hadrons and muons and high intensity up to 10^6 per accelerator spill at 27 GeV was setup at U70 accelerator in Protvino, Russia. A beam tagging system based on drift chambers with 160 micron resolution was able to measure relative electron beam momentum precisely. The resolution sigma_p p was 0.13% at 45 GeV where multiple scattering is negligible. This test beam setup provided the possibility to study properties of lead tungstate crystals (PbWO_4) for the BTeV experiment at Fermilab.

The electromagnetic calorimeter for a new Fermilab collider program named BTeV is based on lead tungstate scintillating crystals (PbWO4). Various properties of crystals manufactured by Russian and Chinese companies were measured at the U70 accelerator in Protvino. A dedicated beam momentum tagging system was used to measure the energy and spatial resolution.