Ioan Dafinei Regional Centre ECAL-CMS Rome ITALY Villa Olmo, Como 15-19 October 2001 Advanced Technology and Particle Physics Lead Tungstate Crystals for the CMS Electromagnetic Calorimeter at the LHC Ioan Dafinei I.N.F.N. Sezione di Roma, Rome ITALY (on behalf of CMS ECAL Collaboration)
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Ioan Dafinei Regional Centre ECAL-CMS Rome ITALY Villa Olmo, Como 15-19 October 2001 Advanced Technology and Particle Physics Lead Tungstate Crystals for.
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Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Lead Tungstate Crystals for the CMS Electromagnetic Calorimeter at the LHC
Ioan DafineiI.N.F.N. Sezione di Roma, Rome ITALY
(on behalf of CMS ECAL Collaboration)
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Index
1. Introduction
2. PWO General Properties
- Luminescence Spectrum
- Scintillation characteristics
- Radiation hardness
3. PWO for ECAL-CMS
- R&D Short Review
- Requisites & Qualification Parameters
- Regional Centers
4. Preproduction Crystal Properties Present Status
5. Recent Developments in PWO Crystal Growth Technology
6. Conclusions
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Introduction
Requirements for scintillators to be used for ECAL construction
ECAL-CMS
high density and high Z
• mechanical ruggedness• chemical stability• uniformity of properties• low price
small X0
small Rm
large LY
short dead time fast
radiation hard
technological requirements
high stopping power
high granularity
high energy resolution
LHC
Luminosity 1034 cm-2·s-1
Bunch separation 25 ns
emission spectrum overlapping with spectral sensitivity of commonly used photodetectors
•creation of color centres is quenched by appropriate doping
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
R&D Short Review
• 1992 : Crystal2000 Conference• 1994 : choice of PWO for CMS-ECAL• 1994-1998 : R&D phase
0
20
40
60
80
100
300350 400 450500 550600650700
Tra
nsm
issi
on
(%
)
Wavelength (nm)
Theoretical transmission
'95 crystal
'98 crystal
• 1998-2000 : Pre-Production of 6000 crystals• 2001 : Start of the Production
1995 1998
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
R&D Short Review
Goals of Pre-production Activity
For Producer : Increase the rate of production Improve the crystal quality and homogeneity of properties
For CMS-ECAL communitySetting up the Regional Centres Installation of Automatic Crystal Control System (ACCOS) (machines designed to make the full characterisation of 30 crystals in 7 hours)
All the 6000 crystals have been measured on ACCOS at CERN
800 re-measured on ACCOR at Rome (ACCOS-ACCOR intercalibration)
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Requisites & Qualification Parameters
Qualification parametersLight Yield
• LY@8X0 8 pe/MeV at 18°C
• -0.35 %/X0 FNUF +0.35 %/X0
• LY(100ns)/LY(1s) > 90%
LY@8X0 =7.5·a+b
FNUF =100·(-0.89·a)/(11.5·a+b)
LY(x)= a · x+b
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Requisites & Qualification Parameters
Qualification parametersTransmission
•LT360nm 25%
•LT420nm 55%
•LT620nm 65%
•LTslopeinflection > 3%/nm
TT=50% 3nm
0
20
40
60
80
300 400 500 600 700
LT1535557595115135155175195215
Tra
ns
mis
sio
n (
%)
wavelength (nm)PWO1713_Ro.QPC
TTLT
Check general quality and radiation resistance
LT
TT
T=p2·exp(-(p3)/w-exp((p0-w)·p1))
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
•dimensions within +0.00 mm , -0.10 mm of nominal values
•planarity for all faces within 0.02 mm
•chamfers between 0.3 mm and 0.7 mm
•polished faces with roughness < 0.020 m
•unpolished face with roughness = 0.350 m
ECAL-CMS
Requisites & Qualification Parameters
Qualification parametersDimensios !
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Regional Centers
CERN Lab.27 Regional Center
Dimensions
Light yield uniformity
Transmission
ACCOCE http://cmsdoc.cern.ch/cms/ECAL/html/wp/rc/
CERN Lab.27 EP-CMA
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
Regional Centers
Rome, Italy Regional Center http://www.roma1.infn.it/exp/cms/
Casaccia
Co60
PM
LED
Light yield uniformity
Dimensions
Coord3 S.p.A.
Dark roomtemperature : 20±0.5°C rel. humidity: 50±10%
ACCOR
Capacity:35 crystals/run1 run time:approx. 10 hours Transmission
Dose (Gy)PWO_batchP2lowdoselab27_1.qpc E. Auffray, EP_CMA10/06/2001
Front irrad., 1.5Gy, 0.15Gy/h
Ioan DafineiRegional Centre ECAL-CMS Rome ITALY
Villa Olmo, Como 15-19 October 2001
Advanced Technology and Particle Physics
• Success of the R&D phase– Increase of the production rate
– good quality crystals
– uniform optical properties
• Technology for ingots up to 65mm diameter is now well under control
• The possibility to further increase the as grown PWO diameter and to apply this approach to endcap crystals is realistic
• Present status of physics and technology of scintillating materials shows that the CMS Collaboration decision to use PWO crystals for the ECAL construction was the best possible choice