Calorimetry and Muons
Summary Talk
Andy White
University of Texas at Arlington
LCWS05, SLAC
March 22, 2005
Overview of talk
 Physics processes driving calorimetry and
muon systems designs
 Calorimeter system design
 Different approaches to LC calorimetry
 Integrated detector design issues
 Electromagnetic Calorimeter Development
 Hadron Calorimeter Development
 Muon system/tail-catcher
 Timescales - where we go from here!
Note: Simulation and algorithm work reviewed in next talk.
Physics examples driving calorimeter
and muon system design
Jet energy resolution
Muon
From M.Battaglia – Large Detector Meeting/Paris 2005
Physics examples driving calorimeter
design
Higgs production e.g.
e+ e- -> Z h
Missing mass peak
or bbar jets
separate from WW, ZZ (in all jet modes)
Higgs couplings e.g.
- gtth from e+ e- -> tth -> WWbbbb -> qqqqbbbb !
- ghhh from e+ e- -> Zhh
Higgs branching ratios h -> bb, WW*, cc, gg, 
Strong WW scattering: separation of
e+e- -> WW -> qqqq
e+e- -> ZZ -> qqqq
and e+e- -> tt
Physics examples driving calorimeter
design
-All of these critical physics studies demand:
 Efficient jet separation and reconstruction
 Excellent jet energy resolution
 Excellent jet-jet mass resolution
+ jet flavor tagging
Plus… We need very good forward calorimetry for e.g.
SUSY selectron studies,
and… ability to find/reconstruct photons from
secondary vertices e.g. from long-lived NLSP -> G
Calorimeter system/overall detector design
Initially two general approaches:
(1) Large inner calorimeter radius -> achieve good
separation of e, , charged hadrons, jets,…
Matches well with having a large tracking volume with
many measurements, good momentum resolution (BR2)
with moderate magnetic field, B ~2-3T
But… calorimeter and muon systems become large and
potentially very expensive…
However…may allow a “traditional” approach to
calorimeter technology(s).
EXAMPLES: Large Detector, GLD
Large Detector
Detectors with large
inner calorimeter radius
GLD
Calorimeter system/overall detector design
(2) Compact detector – reduced inner calorimeter radius.
Use Si/W for the ECal -> excellent resolution/separation.
Constrain the cost by limiting the size of the calorimeter
(and muon) system.
This then requires a compact tracking system -> Silicon only
with very precise (~10m) point measurement.
Also demands a calorimeter technology offering fine
granularity -> restriction of technology choice ??
To restore BR2, boost B -> 5T (stored energy, forces?)
EXAMPLE: SiD
SiD
Compact
detector
How big ??
• Area of EM CAL
(Barrel + Endcap)
–
–
–
–
SD: ~40 m2 / layer
TESLA: ~80 m2 / layer
LD: ~ 100 m2 / layer
(JLC: ~130 m2 / layer)
Very large number of
channels for ~0.5x0.5cm2
cell size!
Can we use a “traditional” approach to calorimetry?
(using only energy measurements based on the
calorimeter systems)
60%/E
H. Videau
30%/E
Target region for jet
energy resolution
Results from “traditional” calorimeter systems
- Equalized EM and HAD responses (“compensation”)
- Optimized sampling fractions
EXAMPLES:
ZEUS - Uranium/Scintillator
Single hadrons 35%/E  1%
Electrons 17%/E  1%
Jets 50%/E
D0 – Uranium/Liquid Argon
Single hadrons 50%/E  4%
Jets 80%/E
Clearly a significant improvement is needed for LC.
A possible approach to enhancing
traditional calorimetry
The DREAM (“Dual REAout Module)project – high
resolution hadron calorimetry:
Use quartz fibers to sample e.m. component (only!), in
combination with scintillating fibers
Structure
How to configure for a LC detector?
The Energy Flow Approach
Energy Flow approach holds promise of required solution
and has been used in other experiments effectively – but
still remains to be proved for the Linear Collider!
-> Use tracker to measure Pt of dominant, charged
particle energy contributions in jets; photons measured in
ECal.
-> Need efficient separation of different types of energy
deposition throughout calorimeter system
-> Energy measurement of only the relatively small neutral
hadron contribution de-emphasizes intrinsic energy
resolution, but highlights need for very efficient “pattern
recognition” in calorimeter.
-> Measure (or veto) energy leakage from calorimeter
through coil into muon system with “tail-catcher”.
Don’t underestimate the complexity!
What is a jet?
Note: - It is popular to quote the
averages of these distributions, however
-there are wide variations, and we will
have to develop efficient procedures for
events with e.g.
25% neutral hadrons,
40% EM (all photons?),
35% Charged hadrons
> Challenging task to find all neutral clusters (and not
mis-associate them with a track!)
Integrated Detector Design
VXD
tag b,c
jets
Tracking
system
EM Cal
HAD Cal
Muon
system/
tail
catcher
Integrated Detector Design
So now we must consider the detector as a whole.
The tracker not only provides excellent momentum
resolution (certainly good enough for replacing cluster
energies in the calorimeter with track momenta), but
also must:
- efficiently find all the charged tracks:
Any missed charged tracks will result in the
corresponding energy clusters in the calorimeter
being measured with lower energy resolution and
a potentially larger confusion term.
Integrated Detector Design
- provide excellent two track resolution for correct
track/energy cluster association
-> tracker outer radius/magnetic field size – implications
for e.m. shower separation/Moliere radius in ECal.
- Different technologies for the ECal and HCal ??
- do we lose by not having the same technology?
- compensation – is the need for this completely overcome
by using the energy flow approach?
Integrated Detector Design
- Services for Vertex Detector and Tracker should not
cause large penetrations, spaces, or dead material within
the calorimeter system – implications for inner systems
design.
- Calorimeters should provide excellent MIP
identification for muon tracking between the tracker and
the muon system itself. High granularity digital
calorimeters should naturally provide this – but what is
the granularity requirement?
- We must be able to find/track low energy ( < 3.5 GeV)
muons completely contained inside the calorimeter.
Calorimeter System Design
 Identify and measure each jet energy
component as well as possible
Following charged particles through calorimeter demands
high granularity…
Two options explored in detail:
(1) Analog ECal + Analog HCal
- for HCal: cost of system for required granularity?
(2) Analog ECal + Digital HCal
- high granularity suggests a digital HCal solution
- resolution (for residual neutral energy) of a purely
digital calorimeter??
Calorimeter Technologies
Electromagnetic Calorimeter
Physics requirements emphasize segmentation/granularity
(transverse AND longitudinal) over intrinsic energy resolution.
Localization of e.m. showers and e.m./hadron separation
dense (small X0) ECal with fine segmentation.
->
Moliere radius -> O(1 cm.)
Transverse segmentation  Moliere radius
Charged/e.m. separation -> fine transverse segmentation (first
layers of ECal).
Tracking charged particles through ECal -> fine longitudinal
segmentation and high MIP efficiency.
Excellent photon direction determination (e.g. GMSB)
Keep the cost (Si) under control!
SLAC-Oregon Si-W ECal R&D
Readout development – M.Breidenbach
CALICE – Si/W Electromagnetic Calorimeter
Wafers:
Russia/MSU
and Prague
PCB: LAL design,
production –
Korea/KNU
New design for ECal active gap -> 40%
reduction to 1.75m, Rm = 1.4cm
Evolution of FE chip: FLC_PHY3 -> FLC_PHY4 -> FLC_TECH1
CALICE-ECal - results
Move (completed) module to Fermilab test beam late 2005
ECal work in Asia
Si/W ECal prototype from Korea
Rt= a layer / tungsten = 15.0/3.5 = 4.8
(CALICE ~ 2)
Eff. Rm = 9mm * (1 + Rt) = 52mm
Total 20 layers = 20 X0, 30cm thick
19 layers of shower sampling
Results from CERN beam tests 2004:
29%/E (vs. 18%/E for GEANT4)
S/N = 5.2
Fit curve of 29%/√E
ECal work in Asia (Japan-Korea-Russia)
Fine granularity Pb-Scintillator
with strips/small tiles and SiPM
Previous Pb/Scint module
with MAPMT readout
Study covering
Laser hitting area
(9 pixels)
New GLD ECal
design
ECal test at DESY in 2006?
YAG - 2m precision
Scintillator/W – U. Colorado
Half-cell tile offset geometry
Electronics development is being
pursued with industry
Hybrid Ecal – Scintillator/W with Si layers –
LC-CAL (INFN)
•45 layers
•25 × 25 × 0.3 cm3 Pb
•25 × 25 × 0.3 cm3 Scint.: 25 cells 5 × 5 cm2
•3 planes: 252 .9 × .9 cm2 Si Pads at: 2, 6, 12 X0
Low energy data (BTF)
confirmed at high
energy !!!
11.1%E
Si L3
Si L2
Si L1
e-
•
•
•
•
The LCcal prototype has been built and fully tested.
Energy and position resolution as expected:
E/E ~11.-11.5% /E, pos ~2 mm (@ 30 GeV)
Light uniformity acceptable.
e/ rejection very good ( <10-3)
Calorimeter Technologies
Hadron Calorimeter
Physics requirements emphasize segmentation/granularity
(transverse AND longitudinal) over intrinsic energy
resolution.
- Depth  4 (not including ECal ~ 1)
-Assuming EFlow:
- sufficient segmentation to allow efficient charged
particle tracking.
- for “digital” approach – sufficiently fine segmentation
to give linear energy vs. hits relation
- efficient MIP detection
- intrinsic, single (neutral) hadron energy resolution
must not degrade jet energy resolution.
Hadron Calorimeter – CALICE/analog
Minical –
results from
electron
test beam
SiPM
Full 1m3 prototype
stack – with SiPM
readout. Goal is for
Fermilab test beam
exposure in Spring
2006
APD
APD
chips from Silicon Sensor used
AD
1100-8, Ø 1.1 mm, Ubias~ 160 V
Hadron Calorimeter – CALICE/analog
Cassette production
Support structure being
provided by DESY for test
beam at Fermilab
Hadron Calorimeter – CALICE/digital
(1) Gas Electron Multiplier (GEM) – based DHCAL
Recent results: efficiency
measurements confirm simulation
results, 95% for 40mV threshold.
Multiplicity 1.27 for 95% efficiency.
Next: 1m x 30cm foil production in
preparation for 1m3 stack assembly.
Joint development of ASIC with RPC
500 channel/5layer test mid -’05
30x30cm2 foils
Hadron Calorimeter – CALICE/digital
(2) Resistive Plate Chamber-based DHCAL
Mylar sheet
Resistive paint
1.2mm gas gap
Resistive paint
Mylar sheet
(On-board amplifiers)
Pad array
1.1mm Glass sheet
1.1mm Glass sheet
GND
-HV
Aluminum foil
Tests
Results
Charge
Avalanche mode ~0.1 ÷ 5 pC
Streamer mode 5 ÷ 100 pC
Efficiency
Greater than 95 %
Drops to zero at spacer
Streamer fraction
Plateau of several 100 V where
efficiency > 95% and
streamer fraction < few percent
1 – gas gap versus 2 – gas gap
Larger Q with 1 – gas gap
Similar efficiency
Noise rate
Small ~0.1 – 0.2 Hz/cm2
Different gases
Best: Freon:IB:SF6 = 94.5:5:0.5
Low noise
Muon System/Tail Catcher
- Muon identification/measurement essential for LC
physics program.
- Role(s) of muon system/tail catcher:
-> Identify high Pt muons exiting calorimeter/coil.
But…how much can we do with calorimeter alone?
-> ? Contribute to muon Pt measurement ? Poor
hit position resolution, but long lever arm…
-> Measure the last pieces of high energy hadron
showers penetrating through the coil – but,
this is really measuring the “tail of the tail”.
-> ? Identify possible long-lived particles from
interactions?
Muon Technologies
Scintillator-based muon system development
U.S. Collaboration
Extruded scintillator strips with
wavelength shifting fibers.
Readout: Multi-anode PMTs
GOAL: 2.5m x 1.25m planes for
Fermilab test beam
Muon Technologies
European – CaPiRe Collaboration
TB @ Frascati
TCMT – CALICE/NIU
Extrusion
Cassette
SiPM
location
Goal: Test Beam
Fermilab/2005
Timeline of Beam Tests
2005
2006
2007
2008
2009
>2009
CALICE SiW ECAL
OTHER ECALs
CALICE TILE
HCAL+TCMT
CALICE DHCALs and others
ILCD R&D,
calibration
Combined CALICE TILE
Combined Calorimeters
, tracking, MDI, etc
PFA and shower library Related Data Taking
Phase 0:
Prep.
Phase I: Detector R&D, PFA
development, Tech. Choice
Phase II
From Jae Yu
Timescales for LC Calorimeter and Muon
development
We have maybe 3-5 years to build, test*, and understand,
calorimeter and muon technologies for the Linear Collider.
By “understand” I mean that the cycle of testing, data
analysis, re-testing etc. should have converged to the point
at which we can reliably design calorimeter and muon
systems from a secure knowledge base.
For the calorimeter, this means having trusted Monte Carlo
simulations of technologies at unprecedented small distance
scales (~1cm), well-understood energy cut-offs, and
demonstrated, efficient, complete energy flow algorithms.
Since the first modules are only now being built, 3-5 years is
not an over-estimate to accomplish these tasks!
* See talk by Jae Yu for Test Beam details
“Window for Detector R&D
2004
2005
2006
2007
2008
GDE (Design)
2009
2010
(Construction)
Technology
Choice
Acc.
CDR
TDR
Start Global Lab.
Done!
Det.
Detector Outline
Documents
CDRs
LOIs
Detector R&D Panel
Detector
R&D Phase
Collaboration
Forming
Construction
Tevatron
SLAC B
HERA
LHC
T2K
Comment on R&D efforts
- It is clear that there are a number of parallel/overlapping
R&D efforts.
- This was inevitable, and desirable, in the early LC R&D
period.
- R&D funding is generally limited – we must make optimal use
of those resources we have.
- A World Wide Study R&D panel has been formed.
- Each detector concept will survey R&D activity, needs
-> Hopefully this will provide a basis for more efficient use
of limited R&D resources
Calorimeter
Electromagnetic
Technology
Groups
Silicon-Tungsten
BNL, Oregon, SLAC
Silicon-Tungsten
UK, Czech, France, Korea, Russia
Silicon-Tungsten
Korea
Scintillator/Silicon-Lead
Italy
Scintillator/Silicon-Tungsten
Kansas, Kansas State
Scintillator-Lead
Japan, Russia
Scintillator-Tungsten
Japan, Korea, Russia
Scintillator-Tungsten
Colorado
Calorimeter
From
K.Kawagoe @
ACFA 07
Hadronic (analog)
Hadronic (digital)
Tail catcher
Technology
Groups
Scintillator-Steel
Czech, Germany, Russia, NIU
Scintillator-Lead
Japan
GEM-Steel
FNAL, UTA
RPC-Steel
Russia
RPC-Steel
ANL, Boston, Chicago, FNAL
Scintillator – Steel
Northern Illinois/ NICADD
Scintillator – Lead/Steel
Japan, Korea, Russia
Scintillator-Steel
FNAL, Northern Illinois
RPC-Steel
Italy
CONCLUSIONS
- A vigorous program of Linear Collider calorimetry and
muon/tail catcher development is underway !
- Many results from prototypes – but we should avoid too
much duplication.
- A lot of work has been done with very limited detector
R&D budgets.
- It is critical to carry out an R&D survey and ensure
that Detector R&D proceeds in a timely manner alongside
Accelerator R&D.
This is particularly critical for U.S.-based calorimeter
development which faces significant financial hurdles,
and a long test beam program!