Summary: Available on CMS information server CMS IN 2004/034
CMS Internal Note
The content of this note is intended for CMS internal use and distribution only
1 August 2004
Afterpulse Studies for HF Calorimeter PMTs
U. Akgun, A.S. Ayan, G. Aydin, F. Duru, J. Olson, Y. Onel
The University of Iowa, Iowa City, IA
HF calorimeter readout system uses 2000 Hamamatsu R7525HA PMTs. We are presenting the details
and results of the tests done on afterpulses of these PMTs at the University of Iowa CMS Laboratories,
as well as independent tests done with different techniques by the manufacturer (Hamamatsu). These
analyses shows that CMS HF calorimeter PMTs are going to have less than 1% afterpulse rate during
the 25ns LHC runs.
HF Calorimeter of the CMS experiment will be composed of quartz fibers embedded into iron absorber. The fibers
will carry the Cherenkov light to the Photomultiplier Tubes (PMT). Due to the operating conditions of the Large
Hadron Collider and the position of the HF calorimeter, there are certain requirements that candidate PMTs must
meet (See Table.1).
Table 1: Summary of the HF-PMT Specifications.