Outline

1
The CMS - HF Calorimeters Radiation hard Quartz
Calorimetry

• Outline
• LHC ( ? SLHC) Huge radiation challenge
• Quartz Radiation hard material
• Cherenkov light Filter out junk
• HF calorimeters in CMS Forward physics at LHC
• Rad hard Quartz RD for SLHC

2
LHC (SLHC) Experimental Challenges

• For LHC
• Luminosity L 1034 cm-2 s-1,
• Bunch Crossing (BX) interval D 25 ns,
• High Interaction Rate
• pp interaction rate 109 interactions/s
• Large Particle Multiplicity
• 20 superposed events in each BX
• 1000 tracks into the detector every 25 ns
• High Radiation Levels
• radiation hard detectors and electronics
• In forward CMS region (h 3-5)
  100 Mrad/year ( 107 s)
• Activation of HF 10 mSv/h (60 days LHC
  run/1 day cool-down)

3
LHC to SLHC

• Assume SLHC luminosity L 1035 cm-2s-1 (10 x
  LHC)
• Possible bunch crossing intervals 25 ns, 50 ns
• Some parameters for comparison are (1 LHC year
  107 s)
• LHC SLHC
• L (cm-2s-1) 1034 1035 1035
• BX interval (ns) 25 25 50
• Nint / BX-ing 20 200 400
• dN/d? / BX-ing 100 1000
  1000
• ?L dt (fb-1) 100
  1000 1000
• In forward CMS region (h 3-5) 10 MGy/year

4
Rad hard Quartz Fibers

• Quartz Fibers (QF) with fluorine-doped silica
  cladding (QQF) can stand 20 Grads, with 10
  light loss
• Plastic-clad fibers (QPF) may have 75 losses
  after 5 years at LHC luminosity in high h region
• Quartz Fibers respond to fast charged particles
  by producing Cherenkov light
• PMT Photodetectors (low B) are sensitive to
  radiation mainly through PK windows with 30
  transmission loss at 420 nm (glass)
• Recovery mechanisms, for fibers and PMT, may
  reduce the effects of radiation damage, either in
  a natural way (self-repair in quiet periods after
  exposure), or artificially, for instance like
  thermo-(or photo-)bleaching.
• Need to be understood to describe accurately the
  behaviour of the detector, and its history
• Robust enough for a survival strategy of
  detectors in extreme SLHC radiation conditions???

5

• Typical spectral response of QF shows reduced
  damage
• effects in the region around maximum (420 nm) of
  PMT
• sensitivity (Quantum Efficiency) this is an
  important asset
• of quartz-fiber calorimetry.

6
Characteristics of Cherenkov light from Quartz
Fibers

• In quartz (n1.45) charged particles with b gt1/n
  (0.7) emit Cherenkov light (Threshold 0.2 MeV for
  e, 400 MeV for p)
• Cherenkov angle qc such that cos qc (bn)-1
  (45o for b1)
• Optical fibers only trap light emitted within the
  numerical aperture of the fiber qT (20o with
  axis of fiber)

DRDC P54 (1994) - Development of quartz fiber
calorimetry (A. Contin, P. Gorodetzky, R. DeSalvo
et al.)
7
Sharper shower profiles

• L. R. Sulak Frascati Calorimetry Conf., 1996

R. Wigmans Lisbon Calorimetry Conf., 1999 N.
Akchurin and R. Wigmans Rev. Sci. Instr. 74
(2003)
8
Fast time response

• Y. Onel, Chicago Calorimetry Conf. , June 2006

9
CMS HF Calorimeters

• 2 Quartz Fiber Calorimeters for the forward
  region (3lt h lt5) of CMS
• 250 tons iron absorber (8.8 lI)
• 1000 km quartz fibers (0.8mm diam)
• 2000 PMT read-out
• 36 wedges azimuthally 18 rings radially
• (Segmentation DhxDf 0.175x0.175)

Test beam results of CMS quartz fibre calorimeter
prototype and simulation of response to
high-energy hadron jets - N. Akchurin et al. -
Nucl.Instrum.Meth.A409593,1998 Design,
Performance and Calibration of CMS Forward
Calorimeter Wedges G. Bayatian et al. Eur.
Phys. J. C53, 139, 2008
10
Assembling the wedges

• Manual insertion of the fibers
• Wedges completed with fibers

11
HF at SX5 ready for lowering to the cavern

• Completely assembledHF module

12
HF in UX5 at beam level

• Since lowering to UX5, HFs were in garages, while
  the rest of CMS was lowered to UX5 assembled
• in the garages HFs were commissioned
• one module seen here was extracted and was
  brought to beam level temporarily

13
HF structure and properties
14
Energy resolution of HF

• Electromagnetic energy resolution is dominated by
  photoelectron statistics and can be expressed in
  the customary form. The stochastic term a 198
  and the constant term b 9.
• Hadronic energy resolution is largely determined
  by the fluctuations in the neutral pion
  production in showers, and when it is expressed
  as in the EM case, a 280 and b 11.
• Highly non-compensating e/h 5
• Light yield 0.3 phe/GeV
• Uniformity (transverse) 10
• Precision in h 0.03 and in f 0.03 rad

15
2007 CMS Global Runs
As 2007 progressed an increasing number of the
following subsystems participated in the global
runs (in order of entrance)

• HF forward hadron calorimeter
• DT drift tubes
• EB barrel electromagentic calorimeter
• RPC resistive plate chambers
• CSC cathode strip chamber
• Trk FEDs/RIB tracker front-end
  drivers/rod-in-a-box
• Lumi luminosity monitor
• HB barrel hadron calorimeter
• HO outer hadronic calorimeter
• HE endcap hadron calorimeter
• HLT high level trigger

HF in all global runs, since beginning 2007
16
HF calibrations solo and in GR

• Events display of the HF calibration data
• (by Ianna Osborne).

17
HF monitoring and calibration tools

• Pedestals long/short term stability
  light-leaks
• LED stability, photoelectron response
• Laser timing
• HV scans gain
• Co60 Source scan calibration 5
• Rad-dam monitoring fiber attenuation damage by
  radiation

18
HF in CMS
19
HF in the forward region of CMS

• Almost complete
• rapidity coverage at LHC

20
HF Physics Benchmark Processes

• High Luminosity
• Higgs production via WW fusion
• pp ? j j (WW) ? H j j (tagging jets in HF)
• Higgs decays to vector bosons
• H ? ZZ (WW) ? l l j j
• - SUSY ? jets ETmiss (hermeticity)
• Rapidity coverage needed h up to 5 for ETmiss
  , 3 lt h lt 5 for tagging forward jets

21
Tagging jets
22
Forward di-jets probe low-x QCD
Moderate Luminosity

• Salim Cerci, David dEnterria
• Mueller-Navelet Jets separated by several ??

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Luminosity Monitor

• Real time lumi monitoring with HF
• Count minimum bias events at low luminosity
• Count zeroes at design luminosity
• Use linear ET sum, which scales directly with
  luminosity.
• Bunch by bunch
• Update time 0.1 s to 1.0 s or slower
• Always on operation, independent of main CMS
  DAQ
• Offline
• Robust logging
• Easy access to luminosity records
• Dynamic range (1028 1034cm2s1)
• Absolute Calibration
• Target 5 (or better)
• Offline TOTEM, Ws Zs
• Simulations Full GEANT with realistic
  representation of photostatistics, electronic
  noise and quantization, etc.
• Minimal hardware requirementsMezzanine board to
  tap into HF data stream
• Autonomous (mini) DAQ system to provide always
  onoperation

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SLHC RD on Rad-hard Quartz
University of Iowa

• As a solution for SLHC conditions quartz plates
  are proposed as a substitute for the
  scintillators at the Hadronic Endcap (HE)
  calorimeter.
• Castor uses Quartz Plates
• A first quartz plate calorimeter prototype (QPCAL
  - I) was built with WLS fibers, and was tested at
  CERN and Fermilab test beams.
• Geant4 simulations are completed
• RD studies to develop a highly efficient method
  for collecting Cerenkov light in quartz with
  wavelength shifting fibers.
• We are also constructing a prototype
  calorimeter, first 6 layers have been tested at
  Fermilab test beam. This summer whole prototype
  will be at Cern test beam.

25
Extracting Cherenkov lightfrom Quartz plates

• Studies and simulations
• The real thing

26
Preliminary results

• Light Enhancement Tools
• PTP and GaZnO (4 Gallium doped) enhance the
  light production almost 4 times. OTP, MTP, and
  PQP did not perform as well as these.
• PTP is easier to apply on quartz, we have a
  functioning evaporation system in Iowa, works
  very well. We also had successful application
  with RTV. Uniform distribution is critical!!
• We tested 0.005 gr/cm2, 0.01 gr/cm2, and 0.015
  gr/cm2 PTP densities on quartz surfaces, looks
  like 0.01 gr.cm2 is slightly better than the
  others.
• ZnO can be applied by RF sputtering, we did this
  at Fermilab- LAB7. We got 0.3 micron, and 1.5
  micron deposition samples. 0.3 micron yields
  better light output.
• Readout Options
• Single APD or SiPMT is not enough to readout a
  plate. But 3-4 APD or SiPMT can do the job.
• Test Beams We have opportunity to test our ZnO
  and PTP covered plates, at CERN (Aug07), and
  Fermilab MTest (Nov 07, and Feb 08).

Blue Clean Quartz Green ZnO (0.3 micron) Red
PTP (2 micron)