Accelerator Physics and detector goals Scintillator calorimeters Conclusions

June 4, Scint 2007 Scintillators and ILC 1

Scintillator calorimeters at ILC

Jaroslav CvachInstitute of Physics ASCR, Prague

CALICE Collaboration

1. Accelerator2. Physics and detector goals3. Scintillator calorimeters4. Conclusions


= International Linear Collider• e+e- machine with two beam pipes each at energy 250 GeV with

cold rf cavities• Lower energy than Large Hadron Collider (LHC, CERN,

Geneva) but more clean interactions – precision physics• LHC will make discovery, ILC will measure it• Detector design goes in parallel with accelerator development


Physics and detectors goals• Interesting reactionsInteresting reactions

ee+ + ee-- -> H,W, Z, t, … -> H,W, Z, t, …

• production of heavy particles decaying into jets

• Goal: to reach energy resolution Goal: to reach energy resolution for jets for jets σσEE/E/E ≈ 30%/√ ≈ 30%/√EE

GeV350

CMSE

ttee

E

%60E

%30

W and Z production

measure every particle:• charged particles in the

tracker• photons in

electromagnetic calo

• neutral hadrons in hadron calo

tracker in strong magnetic field

fine granularity in calorimeters


Four detector concepts• Detectors significantly smaller than at

LHC• Three classical detectors SiD, LDC,

GLD in advance stage• DREAM detector relies on

– Separate measurement of electromagnetic shower component fem using Čerenkov light

– Scintillation fibres measure total hadron energy, clear fibers Č light from electromagnetic energy (π0→γγ) fem

– complementary information about both showers suppresses fluctuations in energy measurement

– See e.g., N. Akchurin etal., NIM A537 (2005) 537

• R&D programs ongoing, do not follow necessarily the detectors but rather different technologies

vertex / tracker

ECAL + HCAL

Muon tracker


Scintillator for calorimeter• Careful R&D program to select

scintillator, shape, WLS fibre, wrapping, photodector position, homogeneity, …

• Final choice: scintillator tiles 5 mm thick of 3 dimensions: 30x30 mm,…

– polysterene + 1.5% PTP + 0.01% POPOP from UNIPLAST, Vladimir, Russia, molding (PHENIX, HERA-B, LHC-B electromagnetic calorimeters)

– Maximum of emmision spectrum at 420 nm

– LY ~ 1.5x lower than Bicron 408

• WLS fibre Kuraray Y11(200), ⌽1mm, different geometry of groove, fibre bent at T ~ 100°C

• Reflector foil super-radiant VN2000 from 3M for top and bottom

• Chemical treatment of tile sides, 2.5% cross-talk over sides

• LY uniformity over tile surface ~ 4%

Light yield in tiles of cassettes 1-26

60 mm

120 mm

30 mm


Hadron calorimeter prototype

SiPM Tile 3х3 cm2,WLS fiber,SiPM

38 planes of scintillating detectors

Light from a tile is read out via WLS fiber and SiPM

SiPM propertiesSensitive area - 1x1 mm2,

Matrix of 1156 (34х34) pixels operating in Geiger mode A fired pixel gives ΔQ= V∙CSo net signal ~ number of

detected photonsLimited dynamic range due to

limited number of pixels saturation at N ~ Npixels

Light registration efficiency QE(~80%) x εGeiger(~60%)х εgeom(~35%) ~ 17%, with maximum for green lightFirst massive use of SiPMsProducer PULSAR, Moscow in

coll. with MEPHI, DESY •Tested and assembled in tiles

by ITEP and MEPHI Moscow•Calorimeter construction at

DESY Hamburg•Tests in beams of DESY,

CERN, FNAL


Parameters of 10000 tested SiPMs

NOISE AT ½ MIP(7.5 pixels) CROSS TALK

SIPM CURRENT

GAIN /103

SATURATION CURVE

E.Tarkovsky, ITEP, ILC 2006, Valencia

Gain ~106 (ΔV~3 V, C~50 fF)Noise ~2MHz, exponentially falls with thresholdOptical inter pixel crosstalk <~ 0.3 restricted operation voltage Insensitive to magnetic field(Tested up to 4 T)Saturation due to the finite number of pixels


Test calorimeter at CERN• CALICE Collaboration – more

than 200 physicists all over the world – calorimeter design

• Task: developement and tests of different technologies in R&D

• European laboratories supported by EU via EUDET grant – 2006-9 (7 M€)

• Calorimeters in tests at CERN, 2006-7, 2008 at FNAL

• Two scintillator calorimeters in line (hadron+TC) – same technology, different scintillator shape

• First massive use of novel photodector – SiPM (> 8000 pcs)

• Aim: proof of principles – calorimeter as „tracking“ device

wavelength shifting fibre

plastic scintillator

SiPM


Event with 2 hadrons after reconstruction. Two showers separated in depth are visible

reconstruction algorithm:Deep Analysis (V. Morgunov, ITEP, DESY)applied to HCAL onlyclusters grouped according to topology and hit amplitudeSeparate: EM and HAD shower components+ neutrons (= isolated hits)

DATA

ECALHCAL


Scintillator ECAL Univ. Kyoto & Shinshu

• Orthogonal scintillator strips in x & y layer from Kuraray

• Size: 1cm x 5cm x 2mm • 30 layers 10 M channels• hole outside shielded by TiO2

• Readout with & w/out WLS fibre by Multi-Pixel Photon Counter (Hamamatsu) (see Satoru Uozumi at the poster session)

9cm

9cm

Cast-Mega-strip

Extruded-strip

T. Takeshita

MPPC

EM-Scintillator-layer model TT Oct 06

MPPCTungsten

MPPC

WLSFscintillator

Flexsheet

Tungsten

Tungsten

particle

1cm

4cm

ASIC

ASIC


Future• Decision about ILC 2010(?)

+ 7 years of construction• Next prototype of scintillator

hadron calorimeter will be built in 2009 (EUDET)

• geometry of the final calorimeter (integration of calibration and read-out electronics

• Direct coupling of SiPM to tile – is it advantegeous?

• Homegeneity from tile with WLS fibre / direct coupling

• Final calorimeter will have ~ 3000 m2 scintillator

38 layers80000 tiles

FEE: 32 ASICs (64-fold)

4 readout lines / layer

Layer dataConcentrator

(control, clock and read FEE)

Module data concentrator

Instrument one tower (e.m. shower size) + 1 layer (few 1000 tiles)

To DAQ

M. Danilov, ITEP


Conclusions• The next generation of calorimeters for the International Linear

Collider aim at significant improvement of the energy resolution

• Two basic methods how to achieve it in scintillator calorimeters:

– Detection of scintillation and Čerenkov light in parallel

– High granular tile calorimeter with Si diodes operated in Geiger mode (SiPM, MPPC, … ) as photodectors

– CALICE Coll. – first massive use of SiPMs (<10000)

• Intensive R&D program ongoing aiming at Engineering Design Report in 2010 with technical solutions and cost estimates as a world-wide activity

• Calorimeter prototypes use plastic scintillators at the moment (not inorganic - the subject of this conference)

• New photodectors can find use also in applications with inorganic scintillators

Accelerator Physics and detector goals Scintillator calorimeters Conclusions

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