CERN Accelerating science

CMS Note
Report number	CMS-CR-2016-145
Title	Phase1 upgrade of the CMS-HF Calorimeter
Author(s)	Gulmez, Erhan (Bogazici U.)
Publication	2016
Collaboration	CMS Collaboration
Imprint	28 Jun 2016
Number of pages	6
Published in:	PoS LHCP2016 (2016) 194
Presented at	4th Conference on Large Hadron Collider Physics 2016 (LHCP 2016), Lund, Sweden, 13 - 18 Jun 2016, pp.194
DOI	10.22323/1.276.0194
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; CMS
Keywords	HCAL
Abstract	In this presentation, results of the Phase I upgrade of the CMS Hadron Forward Calorimeter (HF) are discussed. The CMS-HF Calorimeter was using regular PMTs. Cherenkov light produced in the quartz fibers embedded in the iron absorber was read out with the PMTs. However, occasionally, stray muons hitting the PMT windows cause Cherenkov radiation in the PMT itself and produce large signals. These large signals mimic a very high-energy particle and are tagged as important by the trigger. To reduce this problem, PMTs had to be replaced. The four-anode PMTs that were chosen have thinner windows; thereby reducing the Cherenkov radiation in the PMT window. As part of the upgrade, the read-out electronics is to be replaced so that the PMTs are read out in two channels by connecting each pair of anodes to a single channel. Information provided by these two channels will help us reject the false signals due to the stray muons since the Cherenkov radiation in the PMT window is more likely to produce a signal only in one anode as opposed to a real signal whose light illuminates all four anodes.
Other source	Inspire
Copyright/License	Preprint: (License: CC-BY-4.0)