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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.
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Recent Developments in Diamond Detectors Alexander Oh CERN EPS 2003 Aachen Alexander Oh, CERN
Outline • Introduction • Material Studies • Particle Detector Prototypes • Applications in HEP • Summary Alexander Oh, CERN
The RD42 Collaboration: Institutes from HEP, Heavy Ion Physics, Solid State Physics W. Adam1, E. Berdermann2, P. Bergonzo3, W. de Boer21, 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, Austria 2 GSI, Darmstadt, Germany 3 LETI/DEIN/SPE/CEA Saclay, France 4 LENS, Florence, Italy 5 University of Florence, Italy 6 LEPSI, IN2P3/CNRS-ULP, Strasbourg, France 7 Rutgers University, Piscataway, U.S.A. 8 INFN, Milano, Italy 9 UMM, Cracow, Poland 10 CPPM, Marseille, France 11 II.Inst. f. Exp. Physik, Hamburg, Germany 12 NIKHEF, Amsterdam, Netherlands 13 University of Torino, Italy 14 Ohio State University, Columbus, OH, U.S.A. 15 CERN, Geneva, Switzerland 16 MPI f. Kernphysik, Heidelberg, Germany 17 FNAL, Batavia, IL, U.S.A. 18 Polytechnico Milano, Italy 19 University of Toronto, Canada 20 Universitaet Bonn, Bonn, Germany 21 Universitaet Karlsruhe, Karlsruhe, Germany 22 University of Roma, Italy * Spokespersons 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 : Alexander Oh, CERN
Introduction • Diamond properties Property Diamond Silicon Band Gap [eV] 5.47 1.12 Specific Resistance [Wcm] >1011 2.3× 105 Ionisation Energy [eV] 13 3.6 Ionisation Density MIP [eh/mm] 36 89 • Low e -> low capacitance • Low Ileak -> low noise • Room temperature operation • Fast signal collection time • MIP signal 1.9 smaller for same X0 • Collection efficiency < 100% Alexander Oh, CERN
Introduction • Diamond material • Synthetic diamond • Chemical Vapour Deposition • Polycrystalline films • New: large homoepitaxic mono-crystalline films Alexander Oh, CERN
Growth-Side e R h Substrate-Side Introduction • Principle of detector operation collected charge t d “collection distance” e= Q / Q0 collection efficiency Alexander Oh, CERN
Material Studies Alexander Oh, CERN
Material Studies • Signal vs applied Field: • Saturation above 1 V/mm. • Shape governed by m(E) dependence. • Metallization typicallyCr/AuTi/AuTi/Pt/AuTi/W new Alexander Oh, CERN
Material Studies • Growth Side of a recent polycrystalline CVD diamond Courtesy of Element Six 200mm Alexander Oh, CERN
1 pixel=50 mm x 50 mm Material Studies • Polycrystalline structure has impact on charge collection: Alexander Oh, CERN
Material Studies • Non Uniformities qualitatively reproduced by modeling • Models crystallite growth in 3D • Relates carrier lifetime and crystallite structure. 300mm top-view side-view 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 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. Alexander Oh, CERN
Material Studies • Large Wafer Production (5”) possible 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.) Alexander Oh, CERN
Material Studies • Pion Irradiation 23% improvement in resolution 52% loss of S/N at 2.9 1015p/cm2 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! Alexander Oh, CERN
Material Studies • Mono-crystalline CVD • Perfectly separated from 0e • Narrow Landau distribution • Average 15,000 e Alexander Oh, CERN
Material Studies • Mono-crystalline CVD • Saturation already at 0.2 V/mm • Collection Distance equals Thickness • ~100% efficient Alexander Oh, CERN
Particle Detector Prototypes 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 Alexander Oh, CERN
Pixel Detectors Alexander Oh, CERN
Diamond Pixel Detectors Alexander Oh, CERN
Results from Atlas Diamond Pixel Detectors • Efficiency = 80% • Resolution = digital s=14mm s=115mm Alexander Oh, CERN
Results from CMS Diamond Pixel Detectors s=31mm • Efficiency = 90% • Resolution = digital Alexander Oh, CERN
Applications in HEP 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. 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. Alexander Oh, CERN
Beam condition monitors Looking for increase over normal rate Monitors to be within CMS volume and feed into machine interlock CMS beam monitor • Diamond activity started. • Test beam emulating beam accident in Autumn 2003. • Possible location in the CMS detector : Alexander Oh, CERN
BaBar beam monitor • For production Si PIN diodes are used. • Ubias = 50V, Ileak increases with 1nA/krad • After 100fb-1, noise 50mA, signal 10nA • Since 4 month CVD diamond beam monitor prototype installed • Package must fulfill space constraints • Robustness Alexander Oh, CERN
BaBar beam monitor • Promising results! • Stable operation • Follows closely diode signal 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 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 300mm collection distance. Alexander Oh, CERN
Reserve Alexander Oh, CERN
Strip Detectors Alexander Oh, CERN
CERN test-beam Setup for Diamond Telescope Alexander Oh, CERN
Two planes of the Diamond Telescope Alexander Oh, CERN
Next Step: • Biased intermediate strips to benefit from charge sharing. • Should improve resolution. 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 F0 • Typical increase factor ~1.5 - 1.8 Alexander Oh, CERN
Material Studies • Latest Material measured with 90Sr Source: Research Program was successful ! Alexander Oh, CERN
Material Studies • Proton Irradiation 35% improvement in resolution 15% loss of S/N at 2.2 1015 p/cm2 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 Alexander Oh, CERN