TEC Reconstruction

Since December 2004 I was working as an "Assistent" at the I. Physikalisches Institut B, RWTH Aachen University, Germany. I joined the CMS experiment and work for the CMS Silicon Strip tracker end cap (TEC). The tracking device is built from silicon strip detectors, which are combined into a module with a control and readout unit (the hybrid), environmental sensors and high voltage lines. The structure is made solid with help of a carbon fibre frame.

Those modules are assembled into petals, superstructures which consist of up to 22 modules. The tracker end cap consists of 288 petals, which are organized in nine disks in each end cap. The two end caps close the tracker to either side. The TEC is being built in a large collaboration, and an elaborate logistics planning is needed.

My work consists of:

• TEC Reconstruction: We have taken data with the CMS Laser Alignment system and also recorded data from cosmic muons. I am in charge of reconstructing those particles, and you can take a look at some nice cosmic events.
• Alignment: After building the tracker we will finally take data. To understand these data, a careful calibration of the detector is necessary. Part of the calibration is "alignment": to find out where the sensitive detector parts (the silicon wafers) are with a precision of about 10μm, needed e.g. for the measurement of the W mass.
• TEC Geometry: Weighing parts of the TEC during construction, and validating the existing Tracker geometry with it. Any difference to reality will hinder the comparison between the simulated prediction, where the geometry is used, with the data.
• Bonding: In Aachen, we have a bonding lab for silicon detector modules. After gluing of the modules on an automatic gantry, the sensor strips need to be connected to the readout hybrid that processes the collected charge. I am coordinating the bonding work with the technicians, the gantry center and the petal integration centers. TEC reconstruction is based on the experience from my former project, the TOB Cosmic Rack. I have adopted the so-called "Cosmic Rack Software" to reconstruct tracks also in TEC. More than 30 patches plus a lot of new development was necessary to achieve this. The project started in January 2006. Since then a lot of progress has been reached, and the possibility to get a reasonable alignment does not seem to be far in the future.

  Cosmic events (TEC sector 2, run 21525)

  Event 165
  Event 375
  Event 380
  Event 392

  Laser Alignment event (run 20478)

  Event 611