Pixel Detector Commissioning and Operations

Introduction

The ATLAS detector will soon be put in its closed configuration to allow installation of the remaining beam pipes for LHC operation this summer. The pixel detector has been installed and its components have been tested. However, it would not have been fully tested as an integrated system before the closing of ATLAS. We need to commission it as a detector by itself, and then commission it as part of the entire ATLAS detector. We also have to learn and define the operation of the pixel detector during data taking.

Possible Tasks

There will be a series of related tasks to commission and operate the detector. People will gain invaluable knowledge of how the pixel detector really works. It is very likely that new problems will come up. Thsse are opportunities to delve in detail into specific aspects of the pixel detector. As we cannot predict future problems, here are some earlier issues to illustrate the range of possibilities:

• The opto-boards would not function properly in the pixel's cooled environment. Resistive heaters were added so they would operate at room temperature. The integration of these heaters is still on-going, and could be a project for this summer and beyond.
• Humidity sensors reported unexpectedly high humidity despite a long period of flushing with dry air. We had to go through re-calibration of the humidity sensors to understand and resolve the problem.
• The operational environment involves a large number of voltages, currents, temperature and humidity. These sensors are typically grouped by their functionality, while a more useful overview may involve all sensor types in a geographical region. We need to develop new displays that help the operator correlate the many parameters.
• Data is transmitted optically to and from the detector package and the control and readout electronics. The transmission error rate is affected by several operational parameters, some of which are unique for each channel while others are shared by a number of channels. It was necessary to enhance/develop ways to choose the operational points.

We expect that much of the knowledge and experience gained here will be very useful when people move to CERN and take significant roles in pixel operations later. We also expect some of the knowledge to be relevant for people participating in 3D sensor developments at SLAC.

For additional information, contact Charlie Young.