Status of ATLAS diamond Beam Condition Monitor

Abstract

Beam conditions and the potential detector damage resulting from their anomalies have pushed the LHC experiments to plan their own monitoring devices. The ATLAS Beam Conditions Monitor (BCM) consists of two sets of four detector modules. These are required to be radiation hard (50 Mrad and 10 particles/cm). Each module includes two diamond pad sensors read out in parallel. The sets are located symmetrically around the interaction point at z=±184 cm and r=55 mm (a pseudo-rapidity of about 4.2). Equipped with fast electronics (~2 ns shaping time) these stations measure time-of-flight and pulse height to distinguish events resulting from beam anomalies from those normally occurring in proton-proton interactions. The BCM also provides a coarse measurement of bunch-by-bunch luminosities in ATLAS by counting in-time and outof-time collisions. Eleven detector modules have been fully tested and assembled. Tests performed range from full characterization of diamond sensors to full module tests with electron sources and pion test-beams. Test-beam results in the CERN PS show a module signal to noise of about 11:1 for minimum ionizing particles. The best eight modules have now been installed on the ATLAS Pixel support frame that was installed in ATLAS during the summer of 2007. The final BCM system will be described as well as results of system optimisation, quality assurance, electronics performance evaluation and irradiation tests.