Performance of the Fast Beam Conditions Monitor BCM1F of CMS in the first running periods of LHC

TL;DR

The paper evaluates the performance of CMS's BCM1F, a fast, radiation-hard beam condition monitor using diamond sensors, during the initial LHC runs, highlighting its reliability and operational significance.

Contribution

It presents a detailed characterization of the BCM1F system's performance during early LHC operation, demonstrating its reliability and importance for CMS safety and operation.

Findings

BCM1F operated reliably during initial LHC runs

The system effectively monitors beam conditions on a bunch-by-bunch basis

BCM1F provides crucial data for beam safety and CMS operation

Abstract

The Beam Conditions and Radiation Monitoring System, BRM, is implemented in CMS to protect the detector and provide an interface to the LHC. Seven sub-systems monitor beam conditions and the radiation level inside the detector on different time scales. They detect adverse beam conditions, facilitate beam tuning close to CMS, and measure the doses accumulated in different detector components. Data are taken and analysed independently of the CMS data acquisition, displayed in the control room, and provide inputs to the trigger system and the LHC operators. In case of beam conditions dangerous to the CMS detector, a beam abort is induced. The Fast Beam Conditions Monitor, BCM1F, is a flux counter close to the beam pipe inside the tracker volume. It uses single-crystal CVD diamond sensors, radiation-hard FE electronics, and optical signal transmission to measure the beam halo as well as collision products bunch by bunch. The system has been operational during the initiatory runs of LHC in September 2008. It works reliably since the restart in 2009 and is invaluable to CMS for everyday LHC operation. A characterisation of the system on the basis of data collected during LHC operation is presented.