ECAL review 5 th ILD LAL Orsay May 2011 K. Kawagoe Kobe-U  Kyushu-U in April 2011

The ILD ECAL Finely granular PFA calorimeter with tungsten absorber Cell-size in baseline design ~ 5 x 5 mm 2, num. of cells ~100M in total Necessary to achieve less dead space, low production cost Candidate technologies : Silicon-tungsten Scintillator-tungsten MAPS/DECAL Jet Energy Resolution by M. Thomson Barrel: 5 octogonal wheels R min = 1808 mm; R max = 2220 mm Width = 940 mm End-caps: 4 quarters ∅ min = 800 mm S. 11/05/23ECAL review K. Kawagoe2 R&D studies of ILD ECAL are carried out inside CALICE Collaboration For details of recent works, see slides at CALICE Collaboration Meeting last week at CERN.

Silicon tungsten ECAL status – progress towards DBD “Physics prototype” 10k channel physics prototype 6 years of successful operation at DESY, CERN, FNAL Validated principle and performance Very few signs of aging Calibrations stable with time No problems with e.g. conductive glue dots Connectors can get flaky with repeated re-connections D. Jeans

Integration of ECAL into ILD-like detector addressed within Technological Prototype development Mechanical ~2/3 ILD barrel module under construction mould 1 alveolus mould 3 alveoli Core 2.5m long alveolae (endcap) Fastening system D. Jeans

Silicon sensors Starting discussions directly with Hamamatsu engineers investigate sensor improvements (laser cutting -> reduced edge areas) cost control widen technical requirements (manufacturer chooses thickness...) relax quality requirements (allow few dead pixels, higher leakage current...) Batch of test sensors expected in a couple of months D. Jeans

Front-end electronics SKIROC2 ASIC produced designed for ECAL Si PIN diode readout Low power, power-pulse capability being tested Front end PCB Supports Si sensors and ASICs, Routes data to and from ASICs to outside world Strict requirements on thickness now met by manufacturers Some improvements required (planarity) D. Jeans

Assembly of sensitive detectors Sensor -> PCB gluing ASIC -> PCB Wire bonding HV connection Kapton cables Industrial techniques e.g. Anisotropic Conductive Films Powering, cooling, DAQ Compact, scalable systems under development D. Jeans

Mokka ECAL simulation Good level of realism - dead area at sensor edge - mechanical tolerance between sensors - structural supports within modules - support structure between ECAL and HCAL - ECAL cables and cooling pipes D. Jeans

Summary Silicon tungsten ECAL Established design well developed ideas about detector integration No technical show-stoppers to current design - of course some challenges As always, sensor cost is main concern studies to better understand are continuing in close contact with industry D. Jeans

Scintillator-tungsten ECAL Cost-effective scintillator strip calorimeter aiming to have virtual cells by x-y strips crossing. Beam tests of the physics prototype have been performed to prove feasibility. – DESY 2007 (small prototype) – FNAL 2008, 2009 (test with AHCAL) ILD structure – Scintillator strips with 5 mm width 2 mm thick without WLS fiber – 3 mm tungsten, ~21 X 0 in total Study of “strip-clustering” underway with realistic simulation Remaining Hardware R&D issues : – Study of 5 mm width scintillator-strip without WLS fiber – Dynamic range of photo-sensor – Establish design of the photo-sensor gain calibration system Scintillator strip (4.5 x 1 x 0.3 cm) MPPC WLS fiber 18 cm 72 strips x 30 layers S. 11/05/23ECAL review K. Kawagoe10 Strip-splitting method developed by Katsu has shown good performance.  Two scintillator layers are being constructed to be tested in the same mechanical structure as the SiECAL Technological prototype.  MPPC with more pixels (smaller pixel size) are being developed.

Strip-splitting method An algorithm developed by Katsu to split energy deposit in a strip to virtual square cells using information of adjacent orthogonal layers. After Mark’s tuning of PandraPFA for ScECAL, good jet energy resolution was achieved, although still a little worse than SiECAL. The origin of the difference between SiECAL and ScECAL to be further investigated. 11/05/23ECAL review K. Kawagoe11 w/o strip-splitting with strip-splitting SiECAL Mokka (5mmx5mm) ILD with PandraPFA Strip width: 5mm

ScECAL to the technological prototype Integration of electronics Original idea for ILD – Two scintillator layers of orthogonal directions in a drawer The technological prototype – The mechanical structure is designed for Si- pad layers: required thickness is different – A few scintillator layers are being constructed, but only one layer in each drawer – How to fix the strips in the structure ? Some ideas exist, to be further investigated. Test beam in 2012 electronics strip scintillator 12 11/05/23ECAL review K. Kawagoe12

Flexible Printed Cable MPPC has to stand up on the EBU need a thin flexible connection : FPC FPC+MPPC EBU with SPIROC (DESY) Surface-mount MPPC FPC 11/05/23ECAL review K. Kawagoe13

R&D of 5mm width scintillator strips Direct readout of 5mm width scintillator strips to realize an effective cell size of 5mmx5mm Number of P.E. is roughly 14, good enough. Aiming at good uniformity with small dead region 11/05/23ECAL review K. Kawagoe14 scintillator strip acrylic spacer 3mm MPPC 25  m pitch (1600 pixels) 14

5mm strip improve homogeneity around the MPPC hole hole filled with grease 11/05/23ECAL review K. Kawagoe15 LED-like package for MPPC ?

MPPC evolution Smaller pixel size (more pixels/mm 2 ) – for better dynamic range and linearity – trade off geometrical acceptance for photons 1600 pixel/mm 2 : 25  m pitch – ~36%eff, ~14 p.e. for MIP 2500 pixel/mm 2 : 20  m pitch – ~25% g.e., ~10 p.e. for MIP ? 4400 pixel/mm 2 : 15  m pitch – 35% g.e., ~14% for MIP ?  m pitch 11/05/23ECAL review K. Kawagoe16 20  m pitch 15  m pitch

MPPC bench test compare response curves by a LED PMT MPPC LED (pulse width ~ 5ns) PMT response ADC MPPC res. (p.e.) 11/05/23ECAL review K. Kawagoe17

Possible Idea for baseline design of the ILD ECAL A lot of discussion has been done to form the “Unified ILD ECAL” in this month. 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 established the silicon and Scintillator ECAL technologies. – Need extensive simulation study to determine configuration of Silicon / Scintillator layers – Specific cell & strip combined clustering must be developed. Mokka simulation of the hybrid-type ECAL is under preparation. Two-fold ambiguity with strip clustering Si pads (5x5 mm 2 ) Scint strips (5-10 x 45 mm 2 ) S. 11/05/23ECAL review K. Kawagoe18 Simulation studies are about to start for optimization.

Hybrid ECAL ScECAL with strip-splitting method has shown good performance (stochastic term < 30% at Z pole), close to the SiECAL performance. There should be optimum combination of SiECAL and ScECAL for ILD  Hybrid ECAL with good performance and reasonable cost. 11/05/23ECAL review K. Kawagoe19 Sc/(Si+Sc) Performance Cost Low high low

Hybrid ECAL (cont’d) Hardware R&D: – ECAL technological prototype will have both Si-pad and scintillator-strip layers: good experience to operate two different technologies simultaneously in a same mechanical structure. Simulation studies for optimization – Hybrid ECAL geometry has been already implemented in Mokka. – Strip-splitting method to be implemented in MarlinReco soon. – Tamaki (Kyushu) and new will work on this study. – Various combinations to be studied, for example: SiSiSi…SiSiSiScScSc…ScScSc SiSiScScSiSiScSc…SiSiScScSiSiScSc ScSc…ScScSiSi…SiSiScSc…ScSc 11/05/23ECAL review K. Kawagoe20

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 μm 2 pixels – “TERA Pixel” detector TPAC readout chip v1.0-v1.2 = 168 x 168 pixels; 79.4 mm 2 Expected resolution (pixel counting) 13%/√E(GeV) ⊕ 1% Status: – successful CERN TB of 6 sensors summer 2009 – New SPiDeR collaboration – Physics prototype planned for 2012  Critical points – integration, Power consumption, services – Funding issue for further R&D S. 11/05/23ECAL review K. Kawagoe21 Because of funding problems in UK, currently no plan for physics prototype DECAL. Apart from sensor R&D being continued, only simulation studies have been carried out recently.

DECAL Status Recent resolution studies using HZ/ZZ  4-jet events and  qq pairs ILCSoft v01-10, Mokka 07-06, QGSP_BERT. Use old ILD_00 model, direct comparison of DECAL and SiW (trivially adapted SECal03 driver for DECAL). MarlinReco v00-19, IldCaloDigi, PandoraPFANew v Jet energy resolution extracted with full PFA, 2 very different environments ZZ/HZ case: bin hadronic jets according to their energy, (all at  s = 500 GeV)  pairs, 10 energies,  s = GeV Energy resolutions obtained in our studies (4-jet topology) DECAL (25.5±0.6)%/√E (analogue) SiW (22.3±0.5)%/√E  pairs, DECAL(4.9±0.2)%/√E (analogue) SiW(4.8±0.2)%/√E DECAL performance comparable with baseline ECAL options More straightforward qq (uds) jet resolution, no ISR, etc. to be done 11/05/23ECAL review K. Kawagoe Reco’d PFOs Sim N. Watson

Summary ECAL group is working toward DBD with a strong international collaboration. SiECAL – Physics prototype: successful operation of 6 years at TB – Technological prototype being constructed to establish necessary technology for ILD: sensors, ASIC, PCB, Integration, DAQ, Mechanical structure, and cooling. First (small) test will start in this year. ScECAL – A few layers to be integrated into the technological prototype – Progress in Strip-clustering, 5mm strips, new MPPC. Hybrid ECAL (SiECAL+ScECAL) – is considered seriously, and intensive studies are starting for optimization. MAPS DECAL, currently having financial problems for its R&D, may be considered as an option beyond DBD. 11/05/23ECAL review K. Kawagoe23