2006 – 2009 hf cern summer test beam studies bu team
DESCRIPTION
CMS Hadronic Forward Calorimeter Restoration of Functionality Iowa , BU, FNAL severe descoping of HF in 2002 $$ for HB, tracker - PowerPoint PPT PresentationTRANSCRIPT
CMS Hadronic Forward Calorimeter Restoration of Functionality Iowa, BU, FNAL
severe descoping of HF in 2002 $$ for HB, tracker
tail catcher for late developing hadronic showers - eliminated
½ of quartz fiber gone, quartz cladding replaced with plastic
fiber diameter doubled…2x coarser sampling
insufficient to see muons, the natural calibration…5 GeV/pe
(no other detector in front or behind to cross-correlate)
air light guides from beam region to PM’s outside calorimeter - cutPMs directly in the path of π’s from penetrating showers & from μ’s
fasting timing (1 ns) interpolator removed, cannot kill out of time background
metal envelope, thin-windowed PMs eliminatedinstead thick, all glass PMs
on HF Task Force to ameliorate much of this, some asap, others at Upgrade I
2006 – 2009 HF CERN Summer Test Beam Studies BU team
TB 06 &07 serious problem revealed in CMS mockup in CERN HF Test Beam Cherenkov light from π’s and μ’s traversing PM glass cause
large false high energy depositions…up to 4 TeV equivalent w/ Freeman
critical to physics missions of Hadronic very Forward1) missing energy trigger…may swamp the L1 trigger menu2) tagging jets for high mass Higgs searches for the invisible Higgs
e.g. proposed BU thesis Lawson
TB 08 inserted scintillating crystal tags w/Freemanlong time constant light separable from fast Cherenkov signal?
did not work…scintillation light from thinnest crystals overwhelms Cherenkov
confirmed feasibility of quartz plate tail catcher behind PM box BU
air light guides developed at BUOsborne
prototyped perfected at BU cosmic tower
TB 09 evaluated 4-anode mesh dynode PMs w/Iowa, Fairfield
(and SiPM evaluations also perfected in these Test Beam runs)
1” square, mesh dynode PM…a 1 to 1 replacement for current tube
43% quantum efficiency, makes up for x2 loss of quartz, can calibrate muons
thin front window (~0.5mm), no glass on sides…cuts Cherenkov background tails
4 anodes…tags thru muons, and corrects energy measurement
HF mockup & SiPMs in CMS test beam line at CERN, summer ’09
with µ beam parallel to PM window…
raw PM rate ~20 x bigger with current PM that with mesh PM pulse height 2-5 x bigger than with beam perpendicular
tag Cherenkov window events…and correct energy measurement
corrected energy = 4/3 energy in non-tagged anodesworks beautifully...1 box of 8 PMs to be installed in February
RESERVE
Normalization/calibration:
Single PMT and 4 tower
readout on calorimeter:
HF PMT: R7525
Mini: R9880U-110
4Anode: R7600U-200-M4
1Anode: R7600U-200
150 GeV Muons into PMT at 90°