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Recent Developments in Diamond Detectors. Alexander Oh CERN EPS 2003 Aachen. Outline. Introduction Material Studies Particle Detector Prototypes Applications in HEP Summary. The RD42 Collaboration: Institutes from HEP, Heavy Ion Physics, Solid State Physics. - PowerPoint PPT Presentation
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EPS 2003 Aachen Alexander Oh, CERN
Recent Developments in Diamond Detectors
Alexander Oh
CERN
EPS 2003 Aachen
EPS 2003 Aachen Alexander Oh, CERN
Outline
• Introduction
• Material Studies
• Particle Detector Prototypes
• Applications in HEP
• Summary
EPS 2003 Aachen Alexander Oh, CERN
W. Adam1, E. Berdermann2, P. Bergonzo3, W. deBoer21, F. Bogani4, E. Borchi5, A. Brambilla3,M. Bruzzi5, C. Colledani6, J. Conway7, P. D'Angelo8,W. Dabrowski9, P. Delpierre10, W. Dulinski6,J. Doroshenko7, B. van Eijk12, A. Fallou10, P. Fischer20,F. Fizzotti13, C. Furetta8, K.K. Gan14, N. Ghodbane11,E. Grigoriev21, G. Hallewell10, S. Han14, F. Hartjes12,J. Hrubec1, D. Husson6, H. Kagan14;*, J. Kaplon15,R. Kass14, M. Keil20, K.T. Knoepfle16, T. Koeth7,M. Krammer1, A. Logiudice13, R. Lu13, L. Mac Lynne7,C. Manfredotti13, D. Meier15, D. Menichelli5,S. Meuser20, M. Mishina17, L. Moroni8, J. Noomen12,A. Oh15, M. Pernicka1, L. Perera7, R. Potenza22,J.L. Riester6, S. Roe15, A. Rudge15, S. Sala8,M. Sampietro18, S. Schnetzer7, S. Sciortino5, H. Stelzer2,R. Stone7, C. Sutera22, W. Trischuk19, D. Tromson3,C. Tuve22, B. Vincenzo22, P. Weilhammer15,N. Wermes20, M. Wetstein7, W. Zeuner11, M. Zoeller14
1 HEPHY, Vienna, Austria2 GSI, Darmstadt, Germany3 LETI/DEIN/SPE/CEA Saclay, France4 LENS, Florence, Italy5 University of Florence, Italy6 LEPSI, IN2P3/CNRS-ULP, Strasbourg, France7 Rutgers University, Piscataway, U.S.A.8 INFN, Milano, Italy9 UMM, Cracow, Poland10 CPPM, Marseille, France11 II.Inst. f. Exp. Physik, Hamburg, Germany12 NIKHEF, Amsterdam, Netherlands13 University of Torino, Italy14 Ohio State University, Columbus, OH, U.S.A.15 CERN, Geneva, Switzerland16 MPI f. Kernphysik, Heidelberg, Germany17 FNAL, Batavia, IL, U.S.A.18 Polytechnico Milano, Italy19 University of Toronto, Canada20 Universitaet Bonn, Bonn, Germany21 Universitaet Karlsruhe, Karlsruhe, Germany22 University of Roma, Italy* Spokespersons
The RD42 Collaboration: Institutes from HEP, Heavy Ion Physics, Solid State Physics
EPS 2003 Aachen Alexander Oh, CERN
Introduction• Motivation
– LHC and SLHC radiation levels at inner tracking layers O(1015 n cm-2)
– Detectors close to IP or at low rapidity• Vertexdetector• Beam monitoring
• Some advantageous properties of Diamond compared to Silicon :
EPS 2003 Aachen Alexander Oh, CERN
Introduction• Diamond properties
Property DiamondSilicon
Band Gap [eV] 5.47 1.12Specific Resistance [cm] >1011 2.3 105 Ionisation Energy [eV] 13 3.6Ionisation Density MIP [eh/m] 36 89
– Low -> low capacitance
– Low Ileak -> low noise
– Room temperature operation– Fast signal collection time
– MIP signal 1.9 smaller for same X0
– Collection efficiency < 100%
EPS 2003 Aachen Alexander Oh, CERN
Introduction
• Diamond material– Synthetic diamond– Chemical Vapour Deposition– Polycrystalline films
– New: large homoepitaxic mono-crystalline films
EPS 2003 Aachen Alexander Oh, CERN
Introduction• Principle of detector operation
e
h
Substrate-Side
Growth-Side
td collected charge
“collection distance”
= Q / Q0collection efficiency
EPS 2003 Aachen Alexander Oh, CERN
Material Studies
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Signal vs applied Field:
•Saturation above 1 V/m.
•Shape governed by (E) dependence.
•Metallization typicallyCr/AuTi/AuTi/Pt/AuTi/W new
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Growth Side of a recent polycrystalline CVD diamond
Courtesy of Element Six200m
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Polycrystalline structure has impact on
charge collection:
1 pixel=50 m x 50 m
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Non Uniformities qualitatively reproduced by
modeling• Models crystallite growth in 3D• Relates carrier lifetime and
crystallite structure.
side-view top-view
300m
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Non-uniform charge collection efficiency
• Qualitative description of residual shifts as seen in strip and pixel detectors, caused by electrostatic lateral field component.
T.Lari, A.Oh, N.Wermes (to be published)
Residual shifts measured Lateral field component simulated
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• In 2000 RD42
launched a research program with Element Six to improve the charge collection properties for pCVD diamond.
• Impressive improvements achieved beyond the goal set by RD42.
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Large Wafer Production (5”) possible
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Radiation Hardness
– studied with Protons and Pions on pCVD Strip Detectors
– Fluences of 2-3 1015 particles/cm2
– Generally decrease of leakage current with dose observed.
– Resolution of Strip detectors increase with fluence.– Pions damage more than protons.– 50% loss of S/N at 2.9 x 1015 pions/cm2.– No loss seen for EM radiation up to 10MGy.
(Behnke et al., Nucl.Instrum.Meth. A489 (2002) 230-240.)
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Pion Irradiation
52% loss of S/N at 2.9 1015 /cm2 23% improvement in resolution
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Weaknesses of polycrystalline CVD diamond:
– Many grain boundaries -> defects– Non-uniformity of collection properties
• Mono-crystalline CVD diamond is a solution:– No grain boundaries -> less defects – Uniform collection properties – First samples available!
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Mono-crystalline CVD
•Perfectly separated from 0e•Narrow Landau distribution•Average 15,000 e
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Mono-crystalline CVD
•Saturation already at 0.2 V/m•Collection Distance equals Thickness• ~100% efficient
EPS 2003 Aachen Alexander Oh, CERN
Particle Detector Prototypes
EPS 2003 Aachen Alexander Oh, CERN
Particle Detector Prototypes• Dot detectors
– Characterization
• Strip detectors– Tracking– Slow VA2 and fast LHC electronics– Irradiated and non-irradiated
• Pixel detectors– Tracking – CMS and Atlas patterns / electronics
EPS 2003 Aachen Alexander Oh, CERN
Pixel Detectors
EPS 2003 Aachen Alexander Oh, CERN
• Diamond Pixel Detectors
EPS 2003 Aachen Alexander Oh, CERN
• Efficiency = 80%• Resolution = digital
• Results from Atlas Diamond Pixel Detectors
=115m=14m
EPS 2003 Aachen Alexander Oh, CERN
• Efficiency = 90% • Resolution = digital
• Results from CMS Diamond Pixel Detectors
=31m
EPS 2003 Aachen Alexander Oh, CERN
Applications in HEP
EPS 2003 Aachen Alexander Oh, CERN
Applications in HEP• Vertex detectors with CVD Diamond are not
considered yet as an option for LHC.
• For Beam monitoring CVD Diamond is an option for CMS at the LHC.
• BaBar employs already CVD Diamond in their beam monitoring system.
EPS 2003 Aachen Alexander Oh, CERN
Beam monitoring• For Silicon Vertex systems careful monitoring
is crucial.• Inherently, beam monitors have to be
radiation hard.• Abort Beam when monitors signal dangerous
beam conditions.– False signals must be avoided.– Monitor must be reliable.
• Requirements on the monitoring system depend on the accelerator and vertex system.
EPS 2003 Aachen Alexander Oh, CERN
CMS beam monitor• Diamond activity started.• Test beam emulating beam accident in Autumn 2003.• Possible location in the CMS detector :
Beam condition monitors
Looking for increase over normal rate
Monitors to be within CMS volume and feed into
machine interlock
EPS 2003 Aachen Alexander Oh, CERN
BaBar beam monitor• For production Si PIN diodes are used.
• Ubias = 50V, Ileak increases with 1nA/krad
• After 100fb-1, noise 50A, signal 10nA
• Since 4 month CVD diamond beam monitor prototype installed
• Package must fulfill space constraints
• Robustness
EPS 2003 Aachen Alexander Oh, CERN
BaBar beam monitor• Promising results!
– Stable operation– Follows closely diode signal
EPS 2003 Aachen Alexander Oh, CERN
Summary• Proto-type Detectors
– Dots / Strips / Pixel– Good resolution and S/N 8:1 obtained with rad-
hard electronics– Intermediate Strips are tested this July
• Radiation Hardness– 50% loss of S/N after 2.9 x 1015 pions/cm2
– No loss seen for EM radiation up to 10MGy.– Will be repeated with newest samples
EPS 2003 Aachen Alexander Oh, CERN
Summary
• Application in HEP– Beam monitoring in BaBar– Option for CMS Beam monitoring
• Future– Mono-crystalline CVD diamond– Continue research on poly-crystalline diamond to
reach 300m collection distance.
EPS 2003 Aachen Alexander Oh, CERN
Reserve
EPS 2003 Aachen Alexander Oh, CERN
Strip Detectors
EPS 2003 Aachen Alexander Oh, CERN
• CERN test-beam Setup for Diamond Telescope
EPS 2003 Aachen Alexander Oh, CERN
• Two planes of the Diamond Telescope
EPS 2003 Aachen Alexander Oh, CERN
EPS 2003 Aachen Alexander Oh, CERN
EPS 2003 Aachen Alexander Oh, CERN
• Next Step: • Biased intermediate
strips to benefit from charge sharing.
• Should improve resolution.
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Priming / Pumping
– Increase of signal during radiation
– Filling of traps increases free carrier lifetime
– Empirical fit function:
–
allows to extract priming fluence 0
– Typical increase factor ~1.5 - 1.8
00
0max exp1)( +⎥⎦
⎤⎢⎣
⎡⎟⎟⎠
⎞⎜⎜⎝
⎛
−−⋅−=
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Latest Material measured with 90Sr Source:
Research Program was successful !
EPS 2003 Aachen Alexander Oh, CERN
Material Studies• Proton Irradiation
15% loss of S/N at 2.2 1015 p/cm2 35% improvement in resolution
EPS 2003 Aachen Alexander Oh, CERN
Summary• Charge Collection
– Poly-crystalline CVD diamond:• Most probable signal of ~8000e reached (pCVD)• 99% of charge distribution > 3000e• FWHM / MP ~ 0.95
– Mono-crystalline CVD diamond : • MP signal 13,000e• 99% of charge distribution > 10,000e• FWHM/MP ~ 0.3
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