Radiation hard avalanche photodiodes for CMS ECAL

J. Grahl, I. Kronquist, R. Rusack, A. Singovski, A. Kuznetsov, Y. Musienko, S. Reucroft, J. Swain, K. Deiters, Q. Ingram, D. Renker, T. Sakhelashvili

Research output: Contribution to journalConference articlepeer-review

19 Scopus citations


The photo detectors of the CMS electromagnetic calorimeter have to operate in a rather hostile environment, in a strong magnetic field of 4T 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&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.

Original languageEnglish (US)
Pages (from-to)44-47
Number of pages4
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Issue number1-3
StatePublished - May 21 2003
EventProceedings of the 3rd International Conference on New Development - Beaune, France
Duration: Jun 17 2002Jun 21 2002

Bibliographical note

Copyright 2007 Elsevier B.V., All rights reserved.


  • Avalanche photodiode
  • Calorimeter
  • Photo detector
  • Radiation hardness


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