Status and Performance of the BELLE Electromagnetic Calorimeter 15 mn

A.Kuzmin ?

The BELLE electromagnetic calorimeter consisting of 8736 CsI(Tl) crystals has been operating from the spring of 1999 on KEKB factory. The calorimeter shows good performance and stability. The hardware and software status is presented in the talk. The calorimeter provides the energy resolution of 1.9% for ee ® gamma gamma events and the p0 mass peak resolution of 4.7 MeV. The effects of the radiation background resulted in a pile-up noise as well as possible radiation damage of the crystals are consisdered. The radiation dose for crystals is less then 10 rad/year which is cosistent with the expectation. The measured lightoutput degradation due to the radiation is less than 1% for the closest to the beam crystals.

Operating a Small Angle Calorimeter at BELLE 15 mn

Min-Zun Wang ?

The Extreme Forward Calorimeter (EFC) has been installed at BELLE, KEK. It is made of radiation-hard BGO crystals which have been checked to be good after receiving 100 Mrad dose. The main task of EFC is to offer on-line luminosity information to the accelerator people and to BELLE. Its trigger output also forms different trigger logic for two-photon physics. The calibration procedure and monitoring scheme based on the first year running experience are discussed.

The Lead Tungstate Electromagnetic Calorimeter for CMS 20 mn

R.Brown et al ?

The CMS experiment under construction at CERN will incorporate the largest crystal electromagnetic calorimeter ever built. This calorimeter incorporates 80 000 lead tungstate crystals, each with a mass of more than 1kg. The central (barrel) region of the detector employs avalanche photodiodes to detect the scintillation light, and the forward (endcap) regions are instrumented with vacuum phototriodes. Both types of photodetector have been specifically developed for this application. An overview of the design of the calorimeter will be given, and the status of the project will be reported. Results from test beam studies will be used to illustrate the anticipated performance.

Lead Tungstate Crystal Quality Control for the CMS High Resolution Calorimeter 15 mn

M.Schneegans (LAPP)

Due to the high-performance aimed at for the CMS electromagnetic calorimeter, stringent specifications on crystal quality had to be requested. They concern dimensions, longitudinal and transversal optical transmission, rapidity, quantity and uniformity of the collected scintillation light and resistance to radiations of the Lead Tungstate crystals. In order to check all these parameters for the 80000 crystals of the calorimeter and to record them in a database, fully Automatic Crystal COntrol Systems (ACCOS) have been installed at CERN, Geneva and at ENEA/INFN, Rome. Similar systems are or will be operating at the crystal manufacturing plants. Several of these systems are now operational and are producing results

Uniformization of Light Collection in Lead Tungstate Crystals in View of a High Resolution Calorimeter 15 mn

P.S.Roldan ?

The CMS Electromagnetic Calorimeter will be composed of more than 80.000 lead tungstate crystals. The light collection non-uniformity must be carefully controlled, as the resulting contribution to the energy resolution is required to be small. The procedure chosen to achieve this and the results obtained in the first batches of mass production crystals (comprising more than 3000 PWO crystals) will be presented.

Stability Studies of the Prototype Monitoring System for CMS-ECAL 15 mn

M.Dejardin (?)

A laser light injection and optical fiber distribution system designed to measure the real-time evolution of the optical transmission of each of the 80 000 PbWO4 crystals of CMS near the emission peak is now under construction. The system is designed to achieve an inter-calibration of 0.5%. New results of stability studies with a prototype calorimeter and monitoring system in the CERN test beam are discussed.

Study of the CMS-ECAL Crystal Radiation Damage Monitoring at CERN GIF/X5 Facility 15 mn

A.Singovski ?

The ratio (R) defined as the fractional decrease in the beam signal divided by the fractional decrease in the light monitoring signal under irradiation, was measured at the GIF-X5 facility for a set of 20 CMS ECAL barrel crystals. This ratio is an essential parameter for the light monitoring system which will have to correct for the 5% crystals transmission damage allowed by the CMS crystal specification to the 0.5% precision required by the target ECAL energy resolution. The dependence of R on the wavelength of the injected monitoring light and its path-length in the crystals was studied. Measurements of the inter-crystal variation in R were made for 10pre-production crystals. Dependence of signal loss on the irradiation profile was studied.

A New Type of Lead Tungstate Crystals with High Light Yield 20 mn

Ren-yuan Zhu ?

? Because of their high stopping power and fast scintillation, lead tungstate crystals have attracted much attention in the high energy and nuclear physics communities. The use of lead tungstate, however, is limited by its low light output, and an effort has been made at the Shanghai Institute of Ceramics to improve this. The results indicate that a factor of six increase of the light output, mainly in the microsecond decay component, may be achieved. The light output and decay kinetics, as well as the luminescence and transmittance spectra of new samples, are presented. Possible applications for calorimetry in high energy and nuclear physics experiments are discussed.

Status of the Avalanche Photodiodes for the CMS Electromagnetic Calorimeter 15 mn

D. Renker ?

After 5 years of R&D work the Avalanche Photodiodes for CMS produced by Hamamatsu Photonics have now excellent electrical and optical properties. During the startup of the mass production problems with the reliability and with the radiation hardness have been found. The reasons were identified and counter-measures have been applied.

Testing and Planning for the Usage of Lead Tungstate Calorimeters at Jefferson Lab in the Energy Range of 1 to 6 GeV 15 mn

C.W.Salgado ?

The use of PWO calorimeters is being studied at Jefferson Lab for high resolution measurements and for places where compact calorimetry is necessary. The PRIMEX and CLAS (upgrade) experiments are already considering the use of PWO based calorimeters. We have performed beam tests of several kind of PWO crystals from chinese and russian manufacturers. Preliminary design of calorimeters will be presented. Results from testing using a tagged photon beam in the range of 1 to 6 GeV will be also presented.

The Mainz A4 PbF2 Calorimeter 20 mn

F.Maas ?

The pure Cherenkov radiator Lead Fluoride is for the first time used as a material for a medium scale (1022 crystals) fast (20ns) crystal calorimeter with good energy resolution (3.2% at 1GeV). I will report on the quality control during delivery and setup of the lead fluoride detector modules as well as on first results of the calorimeter in operation in an experiment to measure a parity violating asymmetry in scattering of polarized electrons on unpolarized protons at the MAMI electron accelerator facility in Mainz.