Performance of CMS hadron calorimeter timing and synchronization using test beam, cosmic ray, and LHC beam data

Abstract

This paper discusses the design and performance of the time measurement technique and of the synchronization systems of the CMS hadron calorimeter. Time measurement performance results are presented from test beam data taken in the years 2004 and 2006. For hadronic showers of energy greater than 100 GeV, the timing resolution is measured to be about 1.2 ns. Time synchronization and out-of-time background rejection results are presented from the Cosmic Run At Four Tesla and LHC beam runs taken in the Autumn of 2008. The inter-channel synchronization is measured to be within ±2 ns.

Performance of the CMS hadron calorimeter with cosmic ray muons and LHC beam data

“…In addition, as part of the commissioning of the LHC, the beam was also sent onto collimator targets creating accelerator produced muons. These "beam splash" events proved very useful to determine the relative timing of various the HCAL systems [9], as well as to validate the performance of several components.…”

Development of the CMS detector for the CERN LHC Run 3

“…Corrections for the nonlinearity of the calorimetry system due to its noncompensating response to hadronic and electromagnetic energy depositions have been made [79]. The time resolution for energy deposits in the HB and HE, calculated by weighting the QIE digitization times by the associated energies, is 1.2 ns [80]. The HF energy resolution from the test beam [52] is…”

Performance of the local reconstruction algorithms for the CMS hadron calorimeter with Run 2 data

“…The pulse shape can be extracted with a 1 ns resolution from both test beam data and in situ with pp collision data. The pulse shape with HPDs was measured with a 300 GeV pion test beam prior to LHC collisions [10], while the pulse shape with SiPMs was extracted from pp collision data using isolated bunch collisions. The extraction of the pulse shape was performed by adjusting the time settings of the QIE in 1 ns increments and measuring the pulses with different phases.…”