[en] The CMS electromagnetic calorimeter, containing 80,000 scintillating lead tungstate crystals is designed to give excellent energy resolution in the LHC environment. An overview of the design is given and the current status of the project presented

[en] A simple model of reverse reach-through APDs is described. APD parameters including the dependence of the electric field and gain on the bias voltage, dependence of gain on wavelength are calculated using the McIntyre approach and an assumed doping profile of the APD

[en] Silicon avalanche photodiodes (APDs) have been studied extensively as photosensor candidates for the electromagnetic calorimeter of the CMS detector at LHC. This work presents the measurements of APDs from Hamamatsu and EG and G, with particular emphasis on multiplication factor, spectral response, excess noise factor as well as their dependence on wavelength. The results are compared to the theoretical predictions. Results on the stability of APD gain to bias and temperature drift are also presented

[en] Results on the radiation hardness of photodiodes to fast neutrons are presented. Four photodiodes (three avalanche photodiodes from two manufacturers, and one PIN photodiode) were exposed to neutrons from a ²⁵²Cf source at Oak Ridge National Laboratory. The effects of this radiation on many parameters such as gain, intrinsic dark current, quantum efficiency, noise, capacitance, and voltage and temperature coefficients of the gain for these devices for fluences up to ∼2x10¹³ neutrons/cm² are shown and discussed. While degradation of APDs occurred during neutron irradiation, they remained photosensitive devices with gain

[en] Dependence of the gain and the dark current on bias voltage, has been studied for the S8148 Hamamatsu avalanche photodiode (APD) over a wide range of temperatures. It was found that at T=108 K this APD can operate at a gain close to 10 000. At T=108 K the combination of the S8148 APD operated in proportional mode and the low noise amplifier allows photon counting with high efficiency, while keeping the noise count rate at a relatively low level

[en] Some characteristics and performances of a set of nine Hamamatsu avalanche photodiodes have been investigated. These APDs have equipped a small 3x3 PbWO₄ crystal matrix in X3 beam during the summer of 1995. This note summarizes the main results of this work. An electromagnetic calorimeter with a high resolution is necessary to search for the Higgs if it has a mass between 80 and 160 GeV. A PbWO₄ crystal option has been chosen by the CMS collaboration to achieve this task. The light is collected and converted into an electric charge by an Avalanche Photodiode (APD) followed by a fast preamplifier. The advantage of the APDs is that they are not sensitive to the strong magnetic field when compared to photomultipliers and they are a small nuclear counter effect when compared to PIN diodes. In this study, we have tested nine low capacitance Hamamatsu APDs (S5345) received in spring, 1995 with an area of 0.2 cm². We have measured the capacitance and dark current for each APD. The gain measurements have also been done with gamma sources, continuous and pulsed light. The gain sensitivity versus bias and temperature have also been investigated succinctly. (author). 8 refs., 16 figs., 1 tab

[en] Avalanche Photodiodes (APDs) with improved characteristics are being developed by Hamamatsu Photonics for the electromagnetic calorimeter of the CMS experiment. More than 30 prototypes have been made and investigated during the last 3 years in a development program, that showed significant progress. The parameters of the most recent APDs including the long-term stability and the effect of a high radiation level with a neutron fluence of 2x10¹³ n/cm² have been studied and are presented

[en] The electromagnetic calorimeter of the CMS experiment at CERN's Large Hadron Collider will use 122 400 Avalanche Photodiodes from Hamamatsu Photonics. The design of this APD type is the result of a long R and D program performed by Hamamatsu Photonics and the CMS collaboration. The APD parameters including the behavior under irradiation are discussed in view of our application

[en] We report the results of exposing three APDs (avalanche photodiodes) from two manufacturers, EG and G and Hamamatsu, to a total fluence of 2·10¹³ neutrons/cm² in a fast neutron field produced by ²⁵²Cf at ORNL (Oak Ridge National Laboratory). The effects of this type of radiation on many parameters such as QE (quantum efficiency), voltage coefficient of the gain, wavelength dependence of the gain, intrinsic dark current, and voltage dependent capacitance for these devices are shown and discussed

[en] The photo detectors of the CMS electromagnetic calorimeter have to operate in a rather hostile environment, in a strong magnetic field of 4 T and under unprecedented radiation levels. Avalanche Photo Diodes (APDs) have been chosen to detect the scintillation light of the 62,000 lead tungstate crystals in the barrel part of the calorimeter. After a 6 year long R and D work Hamamatsu Photonics produces APDs with a structure that is basically radiation hard. Only a few percent of the delivered APDs are weak due to defects at the surface caused by dust particles in the production process. Since a reliability of 99.9% is required, a method to detect weak APDs before they are built into the detector had to be developed. The described screening method is a combination of ⁶⁰Co irradiations and annealing under bias of all APDs and irradiations with hadrons on a sampling basis