Speaker
Alan Honma
(CERN)
Description
The CMS Preshower detector is made up of two layers of silicon strip sensors located just behind lead absorber planes for electromagnetic shower energy measurement and position determination. The leakage current measurements from these sensors provides a measure of the radiation damage to the bulk as well as a measure of the distribution of NIEL fluence as a function of pseudorapidity. In addition, anomalously high currents were observed at the start of 7 TeV collisions in 2010 which are attributed to radiation induced surface current. These surface currents have evolved in an interesting way but their underlying mechanism is not yet understood.
Summary
A brief description of the detector will be presented. Then the leakage current measurements that can be attributed to the bulk damage will be shown along with predictions from a FLUKA model using the CMS detector simulation. Finally the observations of anomalous high leakage currents are presented along with evidence showing that they are likely to be surface currents induced by radiation. The evolution of these currents since their appearance in mid 2010 are described.
Author
Alan Honma
(CERN)
Co-authors
Anna Elliott-Peisert
(CERN)
David Barney
(CERN)
