Recent Developments in Diamond Detectors

EPS 2003 Aachen Alexander Oh, CERN

Recent Developments in Diamond Detectors

Alexander Oh

CERN

EPS 2003 Aachen


Outline

• Introduction

• Material Studies

• Particle Detector Prototypes

• Applications in HEP

• Summary


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


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 :


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%


Introduction

• Diamond material– Synthetic diamond– Chemical Vapour Deposition– Polycrystalline films

– New: large homoepitaxic mono-crystalline films


Introduction• Principle of detector operation

e

h

Substrate-Side

Growth-Side

td collected charge

“collection distance”

= Q / Q0collection efficiency


Material Studies


Material Studies• Signal vs applied Field:

•Saturation above 1 V/m.

•Shape governed by (E) dependence.

•Metallization typicallyCr/AuTi/AuTi/Pt/AuTi/W new


Material Studies• Growth Side of a recent polycrystalline CVD diamond

Courtesy of Element Six200m


Material Studies• Polycrystalline structure has impact on

charge collection:

1 pixel=50 m x 50 m


Material Studies• Non Uniformities qualitatively reproduced by

modeling• Models crystallite growth in 3D• Relates carrier lifetime and

crystallite structure.

side-view top-view

300m


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


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.


Material Studies• Large Wafer Production (5”) possible


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.)


Material Studies• Pion Irradiation

52% loss of S/N at 2.9 1015 /cm2 23% improvement in resolution


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!


Material Studies• Mono-crystalline CVD

•Perfectly separated from 0e•Narrow Landau distribution•Average 15,000 e


Material Studies• Mono-crystalline CVD

•Saturation already at 0.2 V/m•Collection Distance equals Thickness• ~100% efficient


Particle Detector Prototypes


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


Pixel Detectors


• Diamond Pixel Detectors


• Efficiency = 80%• Resolution = digital

• Results from Atlas Diamond Pixel Detectors

=115m=14m


• Efficiency = 90% • Resolution = digital

• Results from CMS Diamond Pixel Detectors

=31m


Applications in HEP


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.


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.


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


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


BaBar beam monitor• Promising results!

– Stable operation– Follows closely diode signal


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


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.


Reserve


Strip Detectors


• CERN test-beam Setup for Diamond Telescope


• Two planes of the Diamond Telescope




• Next Step: • Biased intermediate

strips to benefit from charge sharing.

• Should improve resolution.


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)( +⎥⎦

⎤⎢⎣

⎡⎟⎟⎠

⎞⎜⎜⎝

⎛

−−⋅−=


Material Studies• Latest Material measured with 90Sr Source:

Research Program was successful !


Material Studies• Proton Irradiation

15% loss of S/N at 2.2 1015 p/cm2 35% improvement in resolution


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

Documents

Recent Developments in Diamond Detectors