The CMS Fast Beam Condition Monitor for HL-LHC

• Published in: Journal of instrumentation Vol. 19; no. 3; p. C03048
• Main Authors: Auzinger, G., Bakhshiansohi, H., Dabrowski, A., Delannoy, A.G., Dierlamm, A., Dragicevic, M., Gholami, A., Gomez, G., Guthoff, M., Haranko, M., Homna, A., Jenihhin, M., Kaplon, J., Karacheban, O., Korcsmáros, B., Liu, W.H., Lokhovitskiy, A., Loos, R., Mallows, S., Michel, J., Myronenko, V., Pásztor, G., Pari, M., Schwandt, J., Sedghi, M., Shevelev, A., Shibin, K., Steinbrueck, G., Stickland, D., Ujvari, B., Wegrzyn, G.J.
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.03.2024
• Subjects: Aging (artificial); Application specific integrated circuits; Condition monitoring; Data acquisition; Electronics; Large Hadron Collider; Leakage current; Luminosity; Radiation; Radiation effects; Radiation-hard detectors; Service modules; Si microstrip and pad detectors; Solenoids; Systems design
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/19/03/C03048

Abstract The high-luminosity upgrade of the LHC brings unprecedented requirements for real-time and precision bunch-by-bunch online luminosity measurement and beam-induced background monitoring. A key component of the CMS Beam Radiation, Instrumentation and Luminosity system is a stand-alone luminometer, the Fast Beam Condition Monitor (FBCM), which is fully independent from the CMS central trigger and data acquisition services and able to operate at all times with a triggerless readout. FBCM utilizes a dedicated front-end application-specific integrated circuit (ASIC) to amplify the signals from CO 2 -cooled silicon-pad sensors with a timing resolution of a few nanoseconds, which enables the measurement of the beam-induced background. FBCM uses a modular design with two half-disks of twelve modules at each end of CMS, with four service modules placed close to the outer edge to reduce radiation-induced aging. The electronics system design adapts several components from the CMS Tracker for power, control and read-out functionalities. The dedicated FBCM23 ASIC contains six channels and adjustable shaping time to optimize the noise with regards to sensor leakage current. Each ASIC channel outputs a single binary high-speed asynchronous signal carrying time-of-arrival and time-over-threshold information. The chip output signal is digitized, encoded, and sent via a radiation-hard gigabit transceiver and an optical link to the back-end electronics for analysis. This paper reports on the updated design of the FBCM detector and the ongoing testing program.