Accelerator Physics and detector goals Scintillator calorimeters Conclusions
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Transcript of 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
June 4, Scint 2007 Scintillators and ILC 2
= 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
June 4, Scint 2007 Scintillators and ILC 3
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
June 4, Scint 2007 Scintillators and ILC 4
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
June 4, Scint 2007 Scintillators and ILC 5
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
June 4, Scint 2007 Scintillators and ILC 6
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
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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
June 4, Scint 2007 Scintillators and ILC 8
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
June 4, Scint 2007 Scintillators and ILC 9
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
June 4, Scint 2007 Scintillators and ILC 10
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
June 4, Scint 2007 Scintillators and ILC 11
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
June 4, Scint 2007 Scintillators and ILC 12
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