Jet Energy Measurement at ILC Separation of jet particles in the calorimeter is required for the PFA  Fine granular calorimeter is necessary. Particle Flow Algorithm … a new method Rich physics expected in 0.5 – 1 TeV region at ILC : Rich physics expected in 0.5 – 1 TeV region at ILC : e + e -  H, W, Z, tt, SUSY, etc … e + e -  H, W, Z, tt, SUSY, etc …  many quark jets  many quark jets Precise jet energy measurement is the key at ILC. Precise jet energy measurement is the key at ILC. E jet = p e + p  + p charged hadron + E  + E neutral hadron [ tracks only] [calorimeter only] Momentum … can be precisely measured by tracker (charged particles only) Energy … measured by calorimeter, but not as precise as the momentum measurement.

281 physicists/engineers from 47 institutes and 12 countries coming from the 3 regions (America, Asia and Europe) CAlorimeter for the LInear Collider Experiment Main Task : Develop fine granular calorimeter for Particle Flow Algorithm at the ILC experiment. Electromagnetic CAL : Scintillator-Tungsten Silicon-Tungsten MAPS (Monolithic Active Pixel Sensor) Hadron CAL : Analog HCAL (scintillator-based) Digital HCAL

The Scintillator-Strip Electromagnetic Calorimeter Scintillator strip (4.5 x 1 x 0.2 cm) Photo-sensor WLS fiber Sampling calorimeter with Tungsten- scintillator sandwich structure. Scintillator strip structure to achieve fine granularity Huge Number of channels (~10M for ECAL, ~4M for HCAL).  Extruded scintillator + small photo sensor are used to reduce production cost.

Group & Component R&D Scintillator strip by extrusion technique Multi-Pixel Photon Counter Novel type photo-sensor Developed with Hamamatsu The Scintillator-strip Calorimeter Group people from Kobe / Shinshu / Tsukuba / Niigata / Tokyo / Kyungpook universities. We are working on : Establishing component technology (scintillator, photo-sensor, simulation, structure and so on). Beam tests of prototypes to show feasibility. Improvement of the strips Has been studied with KNU colleagues. Several tests has been done.

Calorimeter Prototypes 1 st prototype (2007 Spring): Test feasibility of the sci-strip calorimeter Tested with 1-6 GeV positron DESY 2 nd prototype (2008 fall): Establish the Sci-strip calorimeter technology Tested with 1-32 GeV e -,  -,  -, p Fermilab Tungsten (3.5 mm thick) Scintillator layer (3 mm thick) 18 cm 18 cm 30 layers 2160 channels total Realistic structure (including temp/gain monitoring system)

Beam Tests First prototype DESY in May 2007 (only with positron beams) The scintillator-strip calorimeter has been established by the series of beam tests! Scintillator-strip KEK in Nov nd prototype Fermilab in Sep 2008

Consists of geiger-mode APD pixel matrix. High Gain (10 5 ~10 6 ) Good Photon Detection Efficiency (~15% with 1600 pixel) Compact (package size ~ a few mm) Low Cost Insensitive to magnetic field Dark noise exists ( ~100 kHz) Input vs output is non-linear ~ 1 mm Substrate Development of the Multi-Pixel Photon Counter (MPPC) - a novel semiconductor photo-sensor - We are developing and studying the MPPC with Hamamatsu. for the Sci-strip calorimeter readout. We have already achieved reasonably good performance.

First Prototype and Beam DESY (Mar `07) Photo-sensors (MPPC) Scintillator strip (1 x 4.5 x 0.3 cm) Frame WLS fibre Tungsten (3.5 mm thick) Scintillator layer (3 mm thick) e+e+ 468 channels total (1-6 GeV) Linearity + 1% Energy Resolution for e + Kuraray fiber Kuraray direct Extruded strip

Improvement of scintillator Beam KEK (Nov 2007) extruded TiO 2 No fiber extruded TiO 2 good matching extruded reflector bad matching extruded reflector good matching extruded TiO 2 Kuraray reflector thickness:2mm Kuraray reflector Kuraray reflector reference Beam position (mm) Signal (ADC counts)

2 nd Beam Fermilab ScECAL linearity for electron GeV Electron energy spectra Carried out in Sep 2008 at Fermilab meson test beamline. Goal : establish the base technology of sci-strip calorimeter. Various types of beams have been used : e -,  -,  -, p Beam energy range : GeV first results already show promising performance of the prototype ! 18 cm 18 cm 30 layers Beams

30 o C 25 o C 20 o C 15 o C 10 o C 0 o C -20 o C –C … Pixel capacity –V 0 … Breakdown voltage 30 o C 25 o C 20 o C 15 o C 10 o C 0 o C -20 o C Gain, Dark Noise Rate, Inter-pixel Cross-talk 30 o C 25 o C 20 o C 15 o C 10 o C 0 o C -20 o C Gain comparable to conventional PMTs. Dark noise rate ~100 kHz. Performance is temperature sensitive.  temperature control / monitoring is important. Over-voltage 1600 pixel  V 0 /  T = (56.0±0.1) mV/ o C

Piece-by-piece Variation Piece-by-piece variation is acceptably small.  No need for further selection or categorization on massive use ! Just a small tuning of operation voltages is necessary. Further effort is ongoing by Hamamatsu to make the variation even smaller. Noise Rate (kHz) Over-voltage (V) kHz 400 kHz Gain – 800 pieces Noise Rate 450 pieces

Photon Detection Efficiency (PDE) MPPC 0.5 mm  hole PMT LED WLSF ~ 16 % Measured by njecting same light pulse into both MPPC and PMT, and comparing light yield. MPPC PMT The 1600-pixel MPPC has comparable P.D.E. with normal photomultipliers (15~20%) pixel

Response Curve If the recovery time is very long, MPPC output is defined only by number of pixels. However if the recovery time is shorter than input light, dynamic range may be enhanced. Linearity of 1600 pixel MPPC is not limited by number of pixels thanks to quick recovery time (~4ns). No significant influence from changing bias voltage. Time structure of the light pulse gives large effects in non-linear region. Knowing time structure of input light is important. 8 ns 16 ns 24 ns w = 50 ns 1600 PMT LED w MPPC 1600pix Simulation Slow recovery pix Results

Performancestatus Gain10 5 ~10 6 OK Photon Detection Eff.~0.2 for 1600 pix. MPPCOK Dark Noise Rate~ 100 kHzOK Photon countingGreatOK Bias voltage~ 70 VOK SizeCompactOK Dynamic range Determined by # of pixels and recovery time underway CostExpected to be < $10Negotiating Long-term StabilityUnknown To be checked RobustnessUnknown, presumably goodunderway Radiation hardnessConcernedunderway B fieldExpected to be Insensitive Looks OK Timing resolutionExpected to be 0.1~1 ns To be checked Things done / not yet done

4.5cm 0.4cm 1cm Scintillator Assembly Scintillator strips black sheet Reflector film frame Flexible Cable With MPPC MPPC Flexible Cable With MPPC MPPC

A B C D E F beam Tested Strips typeMethodRead- out Cover Thickness (mm) A1 Extruded Fiber TiO 2 3 No fiber A2good matching B1 Reflector big fiber hole B2matched hole CDirectTiO 2 D Kuraray Direct Reflector 2 E 3 FFiber reference 8 layers with different types of strips 4 strips per one layer were read out. A1,A2,….,F

Setup Veto counter e - beam Sci-Fi Tracker 3x3 cm, fiber  = 1 mm Trigger counters ATLAS SCT 12 cm×6 cm  x ~ 25  m,  y ~ 500  m Movable stage (borrowed from ATLAS group) Scintillator strips Scintillation counter 3x3 cm e - Beam

Calorimeter for the PFA “Figure of Merit for the PFA” B : Magnetic field R : CAL inner radius σ: CAL granularity R M : Effective Moliere radius Separation of jet particles in calorimeter is crucial for the PFA. At the ILC, finely segmented, large, dense calorimeter is required.