Overview of CMS central Hadron Calorimeter

1
Overview of CMS central Hadron Calorimeter

• Sudhakar Katta
• Tata Institute, Mumbai
• CMS Collaboration
•  

2
OUTLINE

• Introduction
• Hadron calorimeter
• Design aspects
• Status of sub detectors HB, HE, HO
• Readout Boxes
• Calibration tools
• Conclusions

3
CMS Detector
4
HCAL

• HF is covering forward region and status of that
  is covered by another talk in this conference(Y.
  Onel).
• Central Hadron calorimeter
• --- HB ? lt 1.3
• --- HE 1.3 lt ? lt 3.0
• --- HO ? lt 1.2
• Tower size 0.087 X 0.087 in ? X ?
• Sampling Calorimeter
• --- brass as absorber
• --- scintillator with wls fiber as active
  medium
• HPD is photo device for reading signal
• Aim to achieve energy resolution of 100/?E?5

5
HCAL

In HB, HE and HO scint samples -gt WLS -gt clear -gt
HPD (in RBX)
HO
RBX
RBX
16
HB
15
HE
6
Need for HO

• In the central region, HB is not thick enough to
  contain hadronic shower fully, particularly those
  fluctuated showers which develop deep inside the
  HCAL.
• Need to extend HCAL outside the solenoid magnet
  and make additional sampling of the shower.
• This part outside the magnet coil is referred as
  Outer Hadron Calorimeter (HO)

7
HO Location

• Geographically located just below the muon
  system and hence is constrained by the geometry
  of the muon system.

8
HO Design Consideration

• Basic Detector Elements should map the
• barrel hadron Calorimeter ( HB) towers
• of granularity 0.087 X 0.087 in h and f.
• Should be able to see MIPS.

10 mm thick Bicron BC408 scintillator to be used
as the active element. Use 0.94 mm dia WLS
Kuraray double clad fibers ( in s shaped
grooves), spliced to clear fibers to carry light
to HPDs.
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Materials

• Scintillator
• -- HB/HE 4 mm Kuraray SCSN81
• --layer0,layer16 are of thickness 9mm for
  HB
• --first layer of HE is from Kharkov
  scintillator
• -- HO 10 mm Bicron BC408
• WLS Fiber ( HB/HE/HO)
• 0.94 mm dia Kuraray Y11 double clad
• Clear Fiber ( HB/HE/HO)
• 0.94 mm dia Kuraray double clad clear
  fiber
• Fiber layout (HB/HE/HO)
• Sigma shape key hole type groove ?
• Absorber
• -- HB/HE Brass (5cm for HB and 8cm for
  HE)
• -- HO coil and Vac tank, TC iron
  (30cm)

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HB details

• HB geometry
• total depth 6 ?
• absorber is 5cm thick brass
• 18 wedges in each of two half barrels
• each wedge covers 20 in ?
• each wedge has 3 megatiles (4x5 in ?)
• length of megatile 3.7m to 4.3m
• 17 layers of megatiles (layer0 to layer16)
• fibers brought to edge of tray to a connector
• total number of tiles 42624
• longitudinal samplings 1 or 2 depending on ?

11
HE details

• HE geometry
• total depth is 10 ?
• absorber is 8cm thick brass
• 19 sampling gaps filled with megatiles
• 18 sectors each covering 20 in ?
• each sector has 2 megatiles(4x5 in ?)
• fibers brought to edge of tray to a connector
• total number of tiles 27500
• Longitudinal samplings 2 or 3 depends on ?

12
HO details

• HO geometry
• the location is just below the muon rings
• we have 6 trays per sector (6x530 in ?)
• we use 4 ? grooves per tile
• we have 5 muon rings 2,-1,0,1,2
• ring 0 has additional layer below TC iron
• fibers brought to edge of tray to two connectors
• RBX will be located on YB1 lower surface
• Total number of tiles 2736
• Longitudinal samplings 1

13
HB/HE/HO

• HB
• Absorber wedges made at Felguera,Spain
• Megatiles(optics) made at Fermilab
• Assembly done at CERN
• HE
• Absorber wedges made at MZOR,Minsk,Belarus
• Megatiles(optics) made at Protvino
• Assembly done at CERN
• HO
• Trays(optics) made in India
• Assembled trays will be sent to CERN

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HO Tray Design
All the tiles in the same f slice of a ring
will be packed as a single mechanical unit called
the tray. It will cover the entire length
of a muon ring along Z. Along F, it will only
be one tile wide ( 50)
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HO Tray Assembly
Tiles in a tray will be covered with tyvek and
tedler. Will be sandwiched between two plastic
plates of 2mm and 1mm thickness for mechanical
stability and ease of handling. 2mm thick plastic
cover will have grooves to route the fibers from
tiles to edge connector. Additional groove for
the source tube
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Light Collection
Clear fibers spliced to WLS fiber will
transport scintillation light to an optical
connector located at the edge of the tray.
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HB wedge design
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Megatile design, top view
Components are the machined scintillator plates,
cover plates, fiber assembly (WLS spliced to
clear fiber, optical connector) pigtails
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Wedges at Felguera
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18th Wedge installed
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HB Optics Quality Control
Over 20,000 scintillator tiles built and
measured RMS of fibers 4.4 RMS of tiles
6.5 RMS of wire/coll 1.2 RMS of average
layer light yield 4.6
22
Installation at CERN
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HB Mechanics and Optics
HB- is installed in SX5, HB is complete and
wedges are stuffed with megatiles in 186. The
repairs of the damaged wedge are completed.
24
HE Absorber at MZOR
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Protvino - Pig Tail QC
RMS of the light yield transmission is less
than 5.
26
Megatile Manufacture -HE
10 megatiles/day at Protvino
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Readout Module (RM) Overview
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RBX Readout Module

• The readout module (RM) integrates the HPD, front
  end electronics, and digital optical drivers.

Optical Sorter ODU
InterfaceCard
HPD Mount
HV
Electronics cards
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RBX Status

• HB RBX in production (Mississippi). Should be
  complete by April 02.
• ODUs for HB complete (Notre Dame) 2-3 rms.
• HE RBX in design. Design should be complete by
  April 02
• Production of HE RBXs late spring
• HE ODUs to be built in ND factory in summer.
• Design HO RBX. Build over summer
• HO ODUs in fall (ND)

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Calibration Tools
E) Test beam - normalization between GeV vs. ADC
vs. A,B,C,D - ratios elec/pion, muon/pion -
before assembly a few wedges, 2002 F) Physics
events - mip signal, link to HO muon - calo
energy scale (e/pi) charged hadron - physics
energy scale photonjet balancing Zjet
balancing di-jets balancing di-jet mass W-gtjj in
top decay
A) Megatile scanner - Co60 gamma source - each
tile light yield - during construction all tiles
B) Moving radio active source - Co60 gamma
source - full chain gain - during CMS-open
(manual) all tiles - during off beam time
(remote) tiles in layer 0 9, all fibers C) UV
Laser - full chain timing, gain-change - during
off beam time tiles in layer 0 9, all
fibers all RBX D) Blue LED - timing, gain
change - during the off beam time all RBX
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In Situ Calibration
A) 1 photon 1 jet - ET Scale over full h
range by photon-jet balancing Note - depend
on ECAL Et scale - sensitive to ISR ( FSR) B) Z
(-gt ee, mm ) 1 jet - ET Scale over full h
range by Z-jet balancing Note - depend on
Tracker and/or ECAL - sensitive to ISR ( FSR)
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FE/DAQ Readout

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Radioactive Source Vertical Slice

• Exercise a single channel of HCAL readout from
  scintillator to computer
• Radioactive Source
• Scintillator
• Optical Fiber
• HPD
• QIE
• Digital optical readout
• HTR
• DCC
• Computer
• First complete 40Mhz readout of HCAL Channel
• Successful demonstration of radioactive source
  measurement for calibration.

34
Conclusions

• HCAL absorber and optics making good progress
• HB- assembled in Sep01, HB will be in Sep02
• HE- absorber is at CERN, HE will be in Oct02
• HO in production, will finish by end of this
  year
• HPDs under control
• Front end and Higher level electronics
  progressing
• Looking forward to test beams in summer 02
• Install electronics Spring 03
• Vertical Slice Tests in SX5 in 03

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The Hadron Calorimeter

• HCAL detects jets from quarks and gluons.
  Neutrinos are inferred from missing Et.

A sampling calorimeter made of brass with
scintillator and WLS. Readout is by HPD. HF uses
quartz and PMT. US does all HB and all
transducers and electronics, RDMS does HE
absorber and optics, India does HO optics, and HF
is done by US,RDMS,CERN,Iran, Hungary and Turkey.
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Beam test results
HO is the critical element to ensure that CMS
calorimetry is everywhere of sufficient depth to
insure a good measurement of the jet energy
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Completed ½ Barrel
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CMS QIE Status

• Testing shows chip fully functional
• Noise as a function of input capacitance being
  studied
• Noise of 3000e- rms achieved with soldered coax
  connections btw HPD and QIE
• Goal is to submit production part by April 02

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QIE under test
TTCrx Clock distributor
QIE Test Board
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Decide on HE ODU by March
Working group Rohlf, Gavrilov, Ruchti,
Kryshkin HE ODU is critical path. Trigger
options for e also.