Final characterization of the ATLAS IBL detector 241 modules with ~(241)Am during the construction phase

摘要

During the first LHC long shutdown (2013/14) a new innermost pixel layer will be added to the present ATLAS Pixel Detector. The Insertable B-Layer (IBL) is a high-reliability, ultra light and radiation hard Pixel Detector assembled with 3D n-in-p and planar n-in-n pixel sensors. Facing the effects of increased luminosity and radiation damage, IBL is expected to improve the b-tagging efficiency, help with pattern recognition performance and add tracking precision with respect to the current detector. Single and double chip modules are loaded on local mechanical support, in the form of 14 staves arranged in cylindrical barrel around the beam pipe. The production of the modules has already started, aiming for a total production of 24 staves including spares. Systematic Quality Assurance (QA) and Quality Control (QC) plans concerning modules, staves and flex from production to final assembly have been put in place. QA is performed in several collaborating institutes and final validation before installation in the ATLAS experiment will be carried out at CERN. Dedicated set-ups have been constructed in order to perform the full chain of QA/QC tests on the production staves. A CO_2 cooling system is used to cool the pixel modules down to -35 °C and an electronic chain similar to the final one has been developed. Furthermore a linear motion system carrying two 241Am sources with an activity of 41 MBq each is mounted over the stave in order to perform a final characterization of the sensor's performance. The realization of source scans on the 24 production staves permits to analyze the response of sensors to radiation, to easily identify dead pixels, and to provide data for an eventual re-calibration of the charge calibration. The setup and first results obtained on prototype staves are described in detail.