CMS HCAL R&D
R&D for Hadron Calorimeter Upgrades
Andris Skuja
University of Maryland
December 5, 2003
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HCAL Upgrades for SLHC
The Super LHC will have a design luminosity of
1035 cm-2/sec
This will be achieved by doubling the number
of bunches as well as doubling the number
of particles or current per bunch
The result will be an increase of radiation levels
everywhere. The problematic regions are HE
above an η of 2 and all of HF
The US groups are investigating possible
upgrades of both regions
Initially, readout electronics will remain as
presently designed running at 40 MHz. It is
felt that off-line software can sort out the
correct beam crossing time to 12.5 nsec
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Mass Reach vs energy and L
N=100 Events, Z' Coupling
VLHC
2 TeV
10
14 TeV
4
LHC
28 TeV
MZ'(GeV)
100 TeV
Tevatron
10
3
10
32
10
33
10
34
Luminosity(/cm2sec)
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
10
35
SLHC Detector Environment
LHC
s
L
 Ldt
Bunch spacing dt
SLHC
14 TeV
14 TeV
2
1034 /(cm  sec) 1035 /(cm2  sec)
1
1
100 fb / yr
1000 fb / yr
25 ns
12.5 ns
N. interactions/x-ing
~ 20
~ 100
dNch/d per x-ing
~ 100
~ 500
Tracker occupancy
Pile-up noise
Dose central region
1
1
1
5
~2.2
10
Bunch spacing reduced 2x. Interactions/crossing
increased 5 x. Pileup noise increased by 2.2x if
crossings are time resolvable.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
VLHC Detector Environment
LHC
s
L
 Ldt
Bunch spacing dt
VLHC
14 TeV
100 TeV
2
1034 /(cm  sec) 1034 /(cm2  sec)
1
1
100 fb / yr
100 fb / yr
25 ns
19 ns
N. interactions/x-ing
~ 20
~ 25**
dNch/d per x-ing
~ 100
~ 250**
Tracker occupancy
Pile-up noise
Dose central region
1
1
1
2.5**
2.5**
5**
** 130 mB inelastic cross section, <Nch> ~ 10, <Et> = 1GeV
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
CMS HCALs
Had Barrel: HB
Had Endcaps:HE
Had Forward: HF
HO
HB
HE
HF
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HCAL : HE and HB
HE
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HB
Optical Design for CMS HCALs
Common Technology for HB, HE, HO
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HF detector
5mm
HAD (143 cm)
To cope with high radiation levels (>1
Grad accumulated in 10 years) the
active part is Quartz fibers: the
energy measured through the
Cerenkov light generated by shower
particles.
EM (165 cm)
Iron calorimeter
Covers 5 >  > 3
Total of 1728 towers, i.e.
2 x 432 towers for EM and HAD
 x f segmentation (0.175 x 0.175)
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HF Fiber stuffing at CERN
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Issues for SLHC
Radiation Damage
Rate Effects
Bunch ID determination
Activation/access
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Scintillator - Dose/Damage
Scintillator under irradiation forms
Color centers which reduce the
Collected light output (transmission loss).
LY ~ exp[-D/Do], Do ~ 4 Mrad
Current operational limit ~ 5 Mrad
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Radiation damage to scintillators
35
10
Dose(Mrad)
10
10
10
10
10
Dose in ECAL and HCAL for L = 10 and One Year
3
Dose per year at SLHV
2
1
0
ECAL
-1
HCAL
-2
0
1
2
3
4
5

Barrel doses are not a problem. For the endcaps a
technology change may be needed for 2 < |y| < 3 for
the CMS HCAL.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Bunch ID: CMS HB Pulse Shape
100 GeV electrons. 25ns bins. Each histo is average
pulse shape, phased +1ns to LHC clock
12 ns difference between circled histo’s  no
problem with bunch ID
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Timing using calorimeter pulse shape
Calculated event time (in clock cycles)
2003 Test Beam
CMS HE
Calculated event time (vertical scale) vs actual event time. CMS HE,
100GeV pions. Watch pile-up though. The faster the calorimeter, the
less important pile-up will be.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HF Cerenkov Calorimeter Pulse Shape
CMS HF
Calorimeter
2003 Test Beam
25 ns
Intrinsically
very fast
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Activation and Radiation Exposure Limits
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Activation in “forward” Region
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Activation in “endcap” Region
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Profitable R&D Directions?
Cerenkov calorimeters are rad-hard and fast 
good candidates for future colliders
• Quartz fiber or plate
• Gas cerenkov
New photon detectors  low cost, small, radhard
• Red-sensitive HPDs
• Geiger-mode photodiodes
New scintillator materials  rad-hard
New directions:
• A number of new calorimeter concepts, some more
realistic for a CMS calorimetry upgrade than others
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Scintillator R&D Approaches
A
B/C
• Blue Tiles
• Current materials
• Em 408-425nm
• Blue Green WLS
• WLS faster than Y11
• EM 490-520nm
• Use in muon system
and for triggering
• Areas of low/moderate
radiation
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
• Blue/Green – Green
Tiles
• Em 490-510nm
• Green/Yellow WLS
• EM 550-560nm
• Benefits:
• Stays short of the
“crevasse” in the
transmission curve.
• In a region of “better”
HPD QE.
• Potentially good
system response.
Optical Attenuation in Fiber
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Example of excitation and emission measurement:
Standard vs New Materials
201T-1 ex, em
204T-1 ex, em K27
700
600
emission
300
excitation
int
400
200
100
0
300
400
500
600
emission
excitation
400
wavelength nm
emission
excitation
400
450
600
305A-1 ex, em DSB2 wls
500
wavelength nm
550
600
int
400
350
300
250
200
150
100
50
0
350
500
wavelength nm
309A-1 ex, em DSB1 wls
int
int
500
450
400
350
300
250
200
150
100
50
0
300
450
400
350
300
250
200
150
100
50
0
350
emission
excitation
400
450
500
wavelength nm
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
550
600
Averaged PMT pulses for a standard scintillation tile
read out with multiclad WLS fibers
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Readout for Red Scintillator
Two Reasonable Choices
DEP HPD with red photocathode
Advantages
Fits into existing RBX and Electronics
Same power supply and control
Small development costs
optimize AR coating
reduce dark count?
ECAL Avalanche Photodiode
Advantages
85% quantum efficiency in the red
Understood and in use in CMS
Cost is only $30/ch
No HV, bias is 200-500 V
Disadvantages
Disadvantages
Only 7% quantum efficiency in red
Cost per tube is high ($150/ch)
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
New fiber attachment system
Modified RBX design
Interface to QIE
Need bias and temperature control
APD & Choice of electronics
ECAL electronics?
QIE with modifications?
Off-Axis detector may use Pixelated APD (Ray Yarema)
Comparison of HPD vs APD must be in the context of the
preamplifier (noise and gain) as well as details of the APD
operation: Gain, temperature, capacitance, etc…
Prisca Cushman has made a number of numerical studies to
compare APDs and HPDs
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
RadHard Scintillator
Readout Upgrade
A Number of investigations will be carried out in 2004
• Compare red sensitive HPD to APD
• Design and build fiber interface to APD
• Design and build interface of APD to QIE
• Optimize APD operating conditions to HCAL
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
New Photodetector: SiPMs
The Silicon Photomultiplier is a Russian invention, reported by Boris Dolgoshein
and colleagues at Moscow Engineering and Physics Institute, Lebedev Physical
Institute, and Pulsar Enterprise (Moscow).
Ref: NIM A 504 (2003) 48 - 52; NIM A 442 (2000) 187-192
SiPM consists of ~10**3 micropixels, size ~30microns, with very thin (0.75
micron) high field depletion layer.
Pixels are resistively isolated, each working in limited Geiger mode as
“binary” devices. The pixels signals are ganged together by aluminum strips
and the summed signal is effectively analog, with dynamic range limited by
the number of pixels (<~ 60% occupancy for good linearity).
Gain ~10**6
Bias voltage ~25V
Broad spectral sensitivity
Sees single pe, and resolves adjacent many-pe peaks with low noise
Works In high magnetic fields
Time resolution ~30ps for 10 pe
Size ~few mm
Cost $10 in large lots ($50 in small lots)
5000 are at DESY for TESLA tile-fiber hadron calorimter
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
SiPMs
Where might we use (or have used) SiPMs?
 CMS HCAL, except possibly for dynamic range. Present SiPM: ~100. If
possible to increase pixel density to 2500 mm-2 and area to (1 cm)**2 ==>
6 x 10**4 dynamic range. Ease FE electronics (?). No HV cables or supply.
Cheap phototransducer.
 Use with RadHard Green/Red tile-fiber calorimeter for
 High eta HE
 S-CMS for SLHC
 TOF for particle ID (a bit far-out)
 I will try to use them (with small blocks of scintillator) for source-garaged
verifiers for all the installed CMS drivers. A nice minor use of the high-gain,
low-voltage and low cost. But hand-held survey meters can do this job
adequately, as we do at CDF!
 Use our imaginations…..
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
SiPMs
Issues:
 How Rad tolerant? (and how much would that matter?)
 Are pixel / device recovery times adequate for LHC (and SLHC)
crossing rates? [higher pixel density ==> smaller C and Q per pixel,
shorter RC. So probably worth pursuing.]
 Availability, delivery times. I’m still waiting after nearly 2 months
for a few samples @$50 per device from Elena Popova, to whom
Dolgoshein referred me. Dolgoshein says PULSAR will do another
large production run in April. I might be able to piggyback a certain
number on that order. Boris did not say what micropixel count and
density.
 Will PULSAR develop larger area SiPM? higher micropixel
density?
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HE: Quartz plate and and
Matching WLS Fiber
HE: Replace HE scintillaor in layers
closest to IP with quartz plate for η >
1.5. We will also need to match the
quartz light output to a WLS fiber.
Iowa, Fairfield and Mississippi will do a
number of trials in 2004 to see if this
proposal is viable.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HF Calorimetry
• The HF detector at LHC has high-OH core, high NA,
hard plastic cladding, QP fibers (quartz core plastic
cladding)
• Iowa group has tested fibers at LIL CERN 500 MeV
electrons NIM A490 (2002) 444
• The HF detector will receive about 100 Mrad/year at
eta=5 with accumulated dose 1-2 Grad/10 years
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
HF Calorimetry
•
The HF region will have much higher doses than LHC environment (1-2
Grad/year and about 20 Grad/10 years)
•
For high radiation doses must use no organic materials
•
We will test special quartz fibers with quartz cladding. These fibers
are Silica/Silica, High-OH, UV enhanced, QQ (Quartz core/ Quartz
cladding) with different type of buffer materials (Acrylic, Polymide,
Aluminum) with different diameters (300, 600, and 800 micron)
•
Fibers will be given 5 x 1017 n/cm2, about 20 Grad
(neutrons with energy > 0.1 MeV)
in IPNS (Intense Pulsed Neutron Source)
at Argonne National Laboratory
•
The range of 10-50 Grad will also be available at this facility.
•
We will test the induced attenuation vs wavelength, transmission of Xe
light in the 350-800 nm range after irradiation. Also measure the
tensile strength before and after the irradiation.
•
These measurements will be important for SLHC R&D for HCAL, HE, HF,
ZDC, & CASTOR forward detectors.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Iowa Polymicro New Rad-hard Quartz
fiber/plate project
Goals:
Determine if optical fibers are capable of functioning in
a radiation environment 10 times the present CMS
detector levels.
If yes, then explore what fiber designs would be best for
the CMS detector upgrade.
Test candidate fiber materials –core, clad and buffer to
determine suitable materials.
Fabricate/Purchase test fibers with materials from step
3.
Test candidate fibers for radiation hardness, mechanical
and optical performance before and after
irradiation.
Develop preliminary fiber specifications
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Iowa Polymicro New Rad-hard Quartz
fiber/plate project
Fiber Designs – conduct review of the fiber designs
suitable for the CMS application. From this review,
select the focus of the design and testing activities.
Focus should be on the fiber design offering the
most chances of success. There are way too many
fiber designs to test all.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Gas Cerenkov S/V LHC Forward
Calorimeter
Oleksiy Atramentov, John Hauptman, Nural Akchurin, Oesa Walker,
Rohit Nabyar
•CMS Note-00-007 “Velocity-of-light Gas …”
•Jim Virdee suggested that we design a calorimeter for the SLHC
•This work funded by LC R&D consortium (Luminosity monitor,
1.4 ns, 1MGy/y, large e/gamma backgrounds)
•For SLHC, think of tungsten, hex rods, 1 meter depth, beta butylene,
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
O
.
A
t
r
Calorimeter design
The Cerenkov light is
generated by shower
particles that cross gas gaps
between absorber elements.
e-
• Shower particles co-move with the Cherenkov light as two
overlapped pancakes. The width of these pancakes is about
12 ps.
• Inside surfaces must be highly reflective at grazing incidence.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Gas Cherenkov Calorimeter:
• The Cherenkov photon signal exits the calorimeter volume at
the velocity of light
Gas has index of refraction n = 1+, ( 10-3), therefore Cherenkov angle is
small
sin θ C  2  .05
and energy threshold for electrons is high
me
Eth 
 11.2 MeV
2
• Decay products from radioactivation of the calorimeter mass
are below Eth and therefore invisible
• A calorimeter made wholly of gas and metal cannot be
damaged by any dose of radiation.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Photon Production
Production of Cherenkov photons by 10 GeV
electron transversing 2mm gas conduits in Pb (a
simulation)
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Geometries: now being simulated
– G3 and G4
• Tubes – reflecting on inside
• Hex rods – reflecting on outside
• “Lasagna” separated functions of absorber
material and reflecting surface
• Other geometries …
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
DREAM Calorimetry:
DREAM Prototype (Upstream)
16.2 cm
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
The detector is made
from 4 mm X 4mm
copper tubes with a
2.5 mm dia hole in
them. There are 19
hexagonal towers
(38 Readout
channels). There
are 5580 copper
tubes total.
The detector weighs
1030 kg.
2 m deep copper is ~10
interaction lengths.
Effective rad.length is
20.10 mm and the
Moliere rad is 20.35
mm
DualReadout = Scintillator +
Quartz
69.3% Cu, scintillating
Quartz fiber
fiber 9.4%, Cherenkov
12.6% and air is 8.7%
3 scintillating and 4 clear
fibers per hole.
Scintillator and the quartz
fiber bundles are
readout separately
with R580 PMTs.
There are 270 tubes per
tower.
Flat-to-flat measures 72
mm and contains
>93% EM shower.
Scintillating
38 PMTs are housed in a
fiber
readout box behind
the detector. Wratten
SCSF-81J Kuraray, QP Polymicro, PJR-FB750 Toray.
3 filter on scintillators.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
100 GeV Pions
Scintillator(rms/mean)=12.3%
Quartz(rms/mean)=19.0%
S(e/pi)=1.22
Q(e/pi)=1.56
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Q(e/h) ~5
S(e/h) ~1.4
Energy Resolution (100 GeV
pions)
The scintillating section of
the detector measures
100 GeV pions with 12.3%
resolution before
correction.
Once the fluctuations in the
EM energy deposition is
removed using the
information from the
quartz section, the
hadronic energy
resolution improves.
After this correction, the
energy resolution
improves dramatically to
2.6%.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Preliminary
Remarks
The combination of scintillator and clear fibers gives a
good handle to measure the electromagnetic
fraction for each event which can be used to
improve hadronic energy resolutions significantly.
If the beam energy is known, like test beams, the
energy resolution can be improved by a factor of ~45. But this assumes the particle energy is already
known. Beware.
If, on the other hand, Ebeam is treated as unknown, the
improvement is ~2-3. Still a big factor.
At the limit, the energy resolution for electrons and
the pions need to be the same once this source of
fluctuation is removed.
Analysis continues.
Interesting but probably not applicable for a CMS
upgrade
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
PPAC – a Rad Hard Detector
Hadron
The light color is solid metal.
Detectors that sample the shower
are shown in darker color.
Detector near front end is for EM shower
Some forward-angle calorimeters for the LHC will
receive huge amounts of radiation, ~100 Grad.
Need detector to be fast, simple, and radiation hard.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Iowa PPAC - a radiation hard
detector
Three flat plates, separated by 2 mm
Middle plate at high voltage
Outer plates hold atmospheric pressure
Filled with 10-40 torr of a suitable gas
Timing resolution better than 300 ps
Will test energy and time resolution at the Advanced
Photon Source (APS) at Argonne
A simple and reliable device for sampling
showers from hadrons and photons.
For highest radiation levels must be made
with no organic materials
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Iowa PPAC - a radiation hard
detector
This PPAC detector concept can be developed as a
candidate for luminosity monitor, HF and ZDC at SLHC.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Iowa PPAC - a radiation hard
detector
Planned tests with double PPAC
•Test with EM showers using 80 ps bunches
of 7 GeV electrons from the Advanced Photon
Source, at Argonne National Laboratory
•Test with low energy hadron showers using
the 120 GeV proton test beam at Fermilab
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
PPAC vs. Scintillating tile
A radiation hard PPAC could be made as a
drop in replacement for a scintillating tile
in HE.
It would fit in the same space and produce
a similar (but faster) signal
Front End electronics would have to be
redesigned
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Iowa/Fairfield
Secondary Emission Sensor Modules for
Calorimeters
Basic Idea:
A Dynode Stack is an Efficient High Gain Radiation Sensor
High Gain & Efficient (yield ~1 e/mip for CsSb coating)
Compact (micromachined metal<1mm thick/stage)
Rad-Hard (PMT dynodes>100 GRads)
Fast
Simple SEM monitors proven at accelerators
Rugged/Could be structural elements (see below)
Easily integrated compactly into large calorimeters
low dead areas or services needed.
SE Detector Modules Are Applicable to:
- Energy-Flow Calorimeters
- Polarimeters
- Forward Calorimeters
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Iowa/Fairfield
Secondary Emission Sensor Modules for
Calorimeters
Basic SEM Calorimeter Sensor Module Form:
“A Flat PMT without a Photocathode”:
- The photocathode is replaced by an SEM film on Metal.
Stack of 5-10 metal sheet dynodes in a metal “window”-ceramic
wall vacuum package about 5-10 mm thick x 10-25 cm square,
adjustable in shape/area to the transverse shower size.
Sheet dynodes/insulators made with MEMS/micromachining
techniques are newly available, in thicknesses as fine as ~0.1
mm/dynode
Ceramic wall thickness can be ~2mm, moulded and fired from
commonly available greenforms (Coors, etc.)
Outer electrodes (SEM cathode, anode) can be thick metal,
serving as absorber and structural elements.
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Iowa/Fairfield
Secondary Emission Sensor Modules for
Calorimeters
Schematic of SEM Calorimeter Sensor
Module
fil m bi as re sistor chain
HV conne cto r
10 mil HV ins ulator (po lymer)
sig nal (fema le) -o ptio nal for s tackin g
-2kV
1cm
brazed ce ramic in sula tors
HV fe male socke t (op tion al for stacking )
Cs3 Sb SEM Su rface
6 d yn odes (200 µm thick @ 0.8 mm s pacing)
sta ckable
1.8 mm thick Cu
sig nal (male )
sig nal out
50ž
ce ramic
15 cm
Cu pl ate
top view
2 s ilicon micro chann el p late s
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003
Acknowledgements
Thanks to Tiziano Camporesi, Jim Freeman and
Dan Green
Slides were contributed by many of our US
CMS Collaborators
•
•
•
•
•
•
•
•
Prisca Cushman
Virgil Barnes
Yasar Onel
Dave Winn
Lucien Crimaldi
John Hauptman
Nural Akchurin
Randy Ruchti and Dan Karmgard
I invite all members of CMS HCAL to contribute
to the upgrade of our calorimeter for SLHC
Andris Skuja – CMS HCAL Meeting at JINR, Dubna on December 5, 2003