The ILD ECAL
- Report on the meeting @ Shinshu
and the ILD workshop @ Paris Satoru Uozumi Feb 17th 2010 WCU meeting
Current situation of ILC & ILD Calorimeter
ILC Detector community
IDAG (International Detector Advisory Comittee)
ILD detector(Asia&Europe&USA)
CALICE
ECAL
SiD(USA)
HCAL
SciW-ECAL (JP,KR)
SiW-ECAL (FR,KR)
MAPS DECAL (EN)
Analog (DESY)
Digital (FR,US)
4th(USA)
• Letter-of-Intent (LoI) have been submitted from each detector concept groups.
• IDAG is evaluating the LoI to select 2 or 1 detector(s).
They also gave several questions which must be answered by end of 2012.
• There are 3 counterpart technologies for the ILD ECAL, but only one design
will be eventually selected.
Now it’s the time to consider how we can take one…
The ILD ECAL
• Finely granular PFA calorimeter with tungsten absorber
• Cell-size in baseline design ~ 5 x 5 mm2, num. of cells ~100M in total
• Necessary to achieve less dead space, low production cost
Jet Energy Resolution
with Particle Flow Algorithm
ILD
ECAL geometry
•
Silicon-tungsten
ECAL
ILD Structure
– 20 layers of 2.1 mm (0.6X0) W
+ 9 layers of 4.2mm (1.2X0)W
– 5x5 mm2 granularity of Si
~ 108 M cells in total
• 10x10 mm2 physics prototype
tested in beam
– Energy resolution measured in test
beam ~ 16.6%/√E(GeV) ⊕ 1.1% with S/N
ratio of 7.5 for a mip signal
– CERN (2006, 2007), FNAL (2008)
• Remaining hardware R&D issues
– Power pulsing of FE electronics
(common issue also for Sci ECAL)
– Si sensor cost reduction
… need 2500 m2,
current price 10 euro/cm2
Scintillator-tungsten ECAL
• Cost-effective scintillator strip calorimeter
aiming to have virtual cells by x-y strips
crossing. (cost ~ 1-2 euro / cm2)
• Beam tests of the physics prototype have
been performed to prove feasibility.
– DESY 2007 (small prototype)
– FNAL 2008, 2009 (test with AHCAL)
– Scintillator strips with 5 mm width
2 mm thick without WLS fiber
– 3 mm tungsten, ~21 X0 in total
• Remaining R&D issues :
– Clustering with strip geometry
– Study of 5 mm width scintillator-strip
without WLS fiber
– Dynamic range of photo-sensor
– Establish design of the photo-sensor gain
calibration system
18 cm
• ILD structure
18 cm
Scintillator strip (4.5 x 1 x 0.3 cm)
WLS
fiber
MPPC
MAPS (DECAL) option
• Potential large cost reductions
– Standard CMOS sensor
– No proprietary processes
– Electronics all on sensor, reduced
fabrication/assembly costs
• Ultimate spatial resolution
– 50x50 μm2 pixels
– “TERA Pixel” detector
• TPAC readout chip
v1.0-v1.2 = 168 x 168 pixels; 79.4 mm2
Expected resolution (pixel counting)
13%/√E(GeV) ⊕1%
• Critical points
– integration, Power consumption,
services
– Funding for further R&D is
recently terminated.
Question from IDAG
•
1.
2.
3.
4.
Each validated detector group will produce a detailed baseline design by 2012.
To this end the following steps are planned.
Demonstrate proof principle on critical components.
– When there are options, at least one option for each subsystem will reach a
level of maturity which verifies feasibility.
Define a feasible baseline design.
– While a baseline will be specified, options may also be considered
Complete basic mechanical integration of the baseline design accounting for
insensitive zones such as the beam holes, support structure, cables, gaps or inner
detector material.
Develop a realistic simulation model of the baseline design, including the
identified faults and limitations.
Discussion at Shinshu & Paris
• In last month at Shinshu meeting, people in SiW and SciW ECAL
group extensively discussed on our future plan.
(http://azusa.shinshu-u.ac.jp/~coterra/francejapan/francejapanA.html)
• The discussion was quite successful, and we got conclusion :
– In order to realize the fine granular ECAL, we must be unified as
the one “ILD ECAL group”.
– To enhance good points and cover weak points on SiW and SciW
ECAL, we will co-operate closely.
– Cost reduction of SiW ECAL … will be discussed with Hamamatsu.
– Problem on clustering with Sci ECAL … might be solved with SiW
ECAL layers.
– One hopeful solution is the “Si+Sci hybrid ECAL”.
Detailed study will be done by 2012.
The Idea of the Hybrid ECAL
Si pads
(5x5 mm2)
Scint strips
(5-10 x 45 mm2)
• One possible idea is a
“hybrid-type ECAL” with silicon pads
and Scintillator-strips.
– The silicon pads in pre-shower and shower-max
region
– The scintillator layers cover after the shower maximum
– Another idea : Si layers interleaved in scintillator layers
– Cost-effective
– No two-fold ambiguity for the strip clustering with silicon sensors
– Can use the established Si and Sci ECAL technologies.
– Need extensive simulation study to determine configuration of
Silicon / Scintillator layers
– Specific cell & strip combined clustering must be developed.
• Simulation of the hybrid-type ECAL is under preparation.
Two-fold ambiguity
with strip clustering
Question from IDAG
•
1.
2.
3.
4.
Each validated detector group will produce a detailed baseline design by 2012.
To this end the following steps are planned.
Demonstrate proof principle on critical components.
– When there are options, at least one option for each subsystem will reach a
level of maturity which verifies feasibility.
Define a feasible baseline design.
– While a baseline will be specified, options may also be considered
Complete basic mechanical integration of the baseline design accounting for
insensitive zones such as the beam holes, support structure, cables, gaps or
inner detector material.
Develop a realistic simulation model of the baseline design, including the
identified faults and limitations.
Next Step : The EUDET prototype
• The EUDET alveolar structure can
accommodate both Si / Sci ECAL modules.
• Discussion underway to make the
compatible structure.
Silicon module
Scintillator module
Heat shield
PCB
Scintillator
Photo-sensor
W slab
• Construction of the mechanical structure
by end-2010.
• Implement detector modules ~ mid 2011.
• Future beam tests from ~ 2012
- Si + Sci module test
Missions to KNU group
• Need to do our best to establish the scintillator part.
– Establish the 5 mm width extruded strips
• mechanical precision, light yield and response uniformity
– Consider R&D of small square scintillator (e.g. 2x2, 1.5x1.5, 1x1 cm2)
• Because of the difficulty of strip clustering,
the Silicon + square-scint ECAL idea is also considered.
• It also could contribute to the HCAL part.
– Analysis of past beam tests
• Satoru, Adil and students in Shinshu are working on it.
– Design of the next EUDET prototype (Satoru, Tohru and FR&DESY colleagues)
• Consider the silicon R&D activity ?
– In case if strip clustering doesn’t work or the SiW cost problem is completely
solved, the ILD ECAL could be the 100% SiW ECAL.
Scint lab status & plan
• We are trying to improve the system with trigger & ADC system.
• The multi-anode PMT gives large amount of dark noise,
and can not be used for the trigger PMT.
• Currently trying with a new trigger PMT delivered in last month.
• Self-triggering with flash ADC is another solution.
Thermostat chamber
VME ADC
DAQ
PC
Gate IN
Sig IN
Trigger
logic
Signal
Voltage source
Scanner
controller
Trigger
PMT
Readout
circuit
Bias
voltage
Scanning stage
• by end of April :
- done with measurement of
1 cm strips, ship it to Japan
• From May :
- Focus on study of 5 mm width
strips.
• Discuss on square tile ?
• Optical simulation
• We would need more man-power !
Backups
Scintillator-ECAL strip clustering
(with Mokka +Pandora PFA)
• Strip clustering with the scntillator-ECAL to make virtual cells from
the strip geometry.
• Study of the strip clustering
extensively underway
• Current result indicates that the JER
doesn’t depend on the shape of the
scintillator, but just changes with its
area.
• Due to the two-fold ambiguity ?
If so, adding small-pixel layer may
resolve it.
Major Milestones to prove Si-Sci-W
ECAL feasibility by end 2012
• Technical points
- Produce short detector slab for both Silicon and Scintillator layers
(by mid 2011) test it with cosmics and beams
- Produce long Silicon detector slab (over ~1.5m) to test signal integrity etc.
(by end 2011)
- Demonstrate power pulsing of FE chips
- First with single chip, short slabs of Si / Sci layers (by mid 2011)
- Then with long slab (by end 2011)
- Test in the magnetic field (by mid 2012)
- Analysis of past test beam data, comparison with simulation (ongoing, ASAP)
- Establish 5 mm width scintillator strip (by ~ 2010/2011)
- Design and produce thin PCB for scintillator/MPPC layers (by mid 2011)
Major Milestones to prove Si-Sci-W
ECAL feasibility by end 2012 (cont’d)
• Simulation (all by mid 2010)
- Implement dead zones of scintillator (photo-sensor, covering films)
Strip
- Implement non-uniformity of strip response MPPC
Strip response
(ADC counts)
- Update ILD Si simulation to same level as
CALICE SiW testbeam simulation
- Implementation of service inside gap
between barrel and end-cap
Position along the strip (cm)
• Reconstruction
- Realistic digitization (end-of-slab instrumentation, MPPC saturation) (by end 2010)
- Clustering with strip and hybrid geometries (by mid 2011)
- Study of PFA performance in different configurations of Si-Sci hybrid ECAL
(by end 2011)
• Detector calibration
- Define ILD ECAL calibration procedure (by end 2011)
Summary
• Technologies and feasibility for the ILD ECAL is being
established (in the CALICE collaboration).
– Several beam test has been done with SiW and SciW ECAL prototypes during
2006-2009.
– Realistic simulation study with PandoraPFA is ongoing.
• Now those technologies are being unified to an idea of the
hybrid-ECAL with the silicon and scintillator layers.
– It could be a possible candidate of the ILD ECAL baseline design.
– Extensive simulation study will be done in next 2 years.
• MAPS pixels for digital ECAL under investigation as an option
beyond the baseline design.
• Still a lot of works need be addressed to finish homework
given by IDAG.
• EUDET technical prototype will be the next stage of the
hardware R&D.
– Several tests will be running from 2010 until the DBD.
Milestones to prove MAPS DECAL
option feasibility by end 2012
• Technical – individual sensor characterization
– Measure MIP efficiency from 2009/10 test beams for sensor variants – by end 2010
• Including epitaxial layer dependence: deep P-well; high resistivity; layer thickness
– Publish essential characterisation data – by end 2010
• Pedestals; noise; response uniformity; trimming; calibration with 55Fe; diffusion time
– Comparison of shower densities in data and simulation - DESY testbeam, March 2010
• Electron response and core shower density
• Results vs. particle energy and vs. material depth
• Single most critical result for DECAL – by early 2011
– Soft photon response downstream of absorber
• Simulation
– Resolution of realistic DECAL to photons – by end 2010
• Study dependence on pixel size; noise; deep P-well; charge diffusion; dead areas, etc.
– Maintain compatibility with SiW analogue geometry/mechanics where appropriate, as expected
for a high performance/lower cost option
• Reconstruction
– Single particle and PFA tuned for DECAL in performance benchmark studies with most complete
simulations – by end 2011
Silicon-tungsten R&D status
TCMT
AHCAL
SiW-ECAL
• Results of 2006 beam test @ CERN
with 2/3 equipped SiW-ECAL
– Highly linear response
– Good energy / spatial resolution
• Analysis of 2007 and 2008 beam test
data with fully equipped SiW-ECAL
currently ongoing.
Silicon-W issues for future R&D
• Dips observed in ECAL response
by inter-wafer gaps.
• Correction works, but dips
cannnot fully recovered.
• Other R&D issues :
• power pulsing of FE electronics
• Si sensors price (3000 m2) currently
10 Euro/cm2
The EUDET ECAL prototype
Issues for the FE Electronics R&D
• PCB thickness < 1.2mm to fit into the EUDET structure
• Next SKIROC2 chip will be submitted for manufacture this month
• Main issue of the test is demostrating the power pulsing
- Test with a single chip in a lab will start soon
- Then it will be again tested in the detector slab
- Also need the test inside B-field to check effect to the changing
current.
The Scintillator-strip Structure and Readout
Scintillator strip
(4.5 x 1 x 0.2 cm)
WLS fiber
MPPC
•Strips made by extrusion.
• Baseline design
… 1 x 4.5 cm strip
• 5 mm strip also feasible,
further R&D necessary.
• Direct readout option w/o
fiber is also being explored.
Calibration System of Photo-sensor Gain
• Light distribution system is
designed to monitor the photosensor gain.
• Photons from LED are
distributed into each scintillator
through a notch on a fiber.
• First system is designed and
tested with the 2nd ScECAL
prototype.
LED
Notches
MPPC output (ADC counts)
Response calibration by MIP
• Need to calibrate response of each individual strip using Minimum
Ionizing Particle (MIP).
• To do that, one possibility is utilizing hadrons in jets as MIPs.
• Simulation result indicates calibration within + 5 % accuracy is
possible with 2-3 days running at high luminosity Z-pole running.
Select isolated
MIPs In jets
Strip response
Strip response
Center-of-mass energy
Days to take +5% calibration
91.2 GeV
200 GeV
500 GeV
2-3 days
400 days
2500 days
ScECAL Geometry
3 mm tungsten
+
2 mm scintillator-strips
+
2 mm readout/service
• Total thickness 172 mm,
corresponds to 20.6X0.
• ~10M channels in total
(case for 1 x 4 cm strip)