Upgraded Fast Beam Conditions Monitor for CMS online luminosity measurement

Abstract

The CMS beam and radiation monitoring subsystem BCM1F during LHC Run I consisted of 8 individual diamond sensors situated around the beam pipe within the tracker detector volume, for the purpose of fast monitoring of beam background and collision products. Effort is ongoing to develop the use of BCM1F as an online bunch-by-bunch luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. To prepare for the expected increase in the LHC luminosity and the change from 50 ns to 25 ns bunch separation, several changes to the system are required, including a higher number of sensors and upgraded electronics. In particular, a new real-time digitizer with large memory was developed and is being integrated into a multi-subsystem framework for luminosity measurement. Current results from Run II preparation will be shown, including results from the January 2014 test beam. Presented at TIPP2014 3rd International Conference on Technology and Instrumentation in Particle Physics, Upgraded Fast Beam Conditions Monitor for CMS online luminosity measurement Jessica Lynn Leonard*, Maria Hempel†, Hans Henschel, Olena Karacheban, Wolfgang Lange, Wolfgang Lohmann†, Roberval Walsh DESY Zeuthen, Germany E-mail:jessica.lynn.leonard@desy.de, maria.hempel@desy.de, hans.henschel@desy.de, olena.karacheban@desy.de, wolfgang.lange@desy.de, wolfgang.lohmann@desy.de, roberval.walsh@desy.de Anne Dabrowski, Vladimir Ryjov CERN Geneva, Switzerland E-mail: anne.evelyn.dabrowski@cern.ch, vladimir.ryjov@cern.ch David Stickland Princeton University Princeton, New Jersey, USA E-mail: david.peter.stickland@cern.ch The CMS beam and radiation monitoring subsystem BCM1F during LHC Run I consisted of 8 individual diamond sensors situated around the beam pipe within the tracker detector volume, for the purpose of fast monitoring of beam background and collision products. Effort is ongoing to develop the use of BCM1F as an online bunch-by-bunch luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. To prepare for the expected increase in the LHC luminosity and the change from 50 ns to 25 ns bunch separation, several changes to the system are required, including a higher number of sensors and upgraded electronics. In particular, a new real-time digitizer with large memory was developed and is being integrated into a multi-subsystem framework for luminosity measurement. Current results from Run II preparation will be discussed, including results from the January 2014 test beam. Technology and Instrumentation in Particle Physics 2014 2-6 June, 2014 Amsterdam, the Netherlands * Speaker † Also at Brandenburg Technical University, Cottbus, Germany  Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it BCM1F for CMS online luminosity Jessica Lynn Leonard 1. Overview of BCM1F The CMS Fast Beam Condition Monitor (BCM1F)[1] provides bunch-by-bunch information on the flux of beam halo and collision products passing through the inner CMS detector[2]. The system was originally designed to monitor the condition of the beam to ensure low enough tracker occupancy for data-taking. However, BCM1F's purpose has evolved to include fast measurement of luminosity in order to function as an online luminometer.