H. Pernegger, CERN, IPRD 2004, May 2004 CVD diamonds: Recent Developments and Applications H. Pernegger, CERN for the CERN RD42 collaboration zOverview uDetector principle uRecent advancements in CVD diamonds and their understanding ÕSignal collection ÕRadiation hardness ÕNew CVD diamonds uApplications in HEP and other fields ÕPixel detector for HEP ÕBeam monitoring & diagnistics ÕMedical application

H. Pernegger, CERN, IPRD 2004, May 2004 Motivation to use CVD diamonds zUse at LHC/SLHC (or similar environments) uPrecision tracking at inner layer required uMust survive the radiation levels typically present at small radia zMaterial properties uRadiation hard (no frequent replacements) uFast signal collection time uCompact + low Z solid state detector uRoom temperature operation zBasic types of material uPoly-crystalline CVD diamond (pCVD) uSingle-crystal CVD diamond (scCVD)

H. Pernegger, CERN, IPRD 2004, May 2004 Basic material constants in comparison zLow dielectric constant- low capacitance zHigh bandgap - low leakage current zFast signal collection zMip signal only 50% of Silicon for same radiation length zCollection efficiency <100% (pCVD)

H. Pernegger, CERN, IPRD 2004, May 2004 Basic Principle of Operation z“Solid state Ionization chamber” uContacts both sides uNo doping or junction required z“planar”  Structured electrodes with sizes from  m to cm zSignal uTypically use integrated amplifiers for readout  Collection distance d =  E   Measured charge Q = d/t Q 0

H. Pernegger, CERN, IPRD 2004, May 2004 Characterization of CVD diamonds zMeasure charge collection distance (through integrating amplifiers) zpCVD diamond “pumps” : signal increase by a factor uFilling of charge traps zContacts: Cr/Au, Ti/W, Ti/Pt/Au uUse dots -> strip -> pixel on same diamond (contacts can be removed)  Typically use 1V/  m as operation point

H. Pernegger, CERN, IPRD 2004, May 2004 CVD diamonds zGrowth side pCVD diamonds wafer grown up to 5 inch zRD42 in research project with Element Six Ltd to increase charge collection distance in pCVD diamond material

H. Pernegger, CERN, IPRD 2004, May 2004 Collection distance on recent pCVD diamonds zNow reach signals of 9800 e- mean charge zMost probable signal 8000e-  CCD = 275  m zResearch program worked zDiamond available in large sizes

H. Pernegger, CERN, IPRD 2004, May 2004 Irradiation studies: Protons up to 2.2 x /cm 2 zSignal (or SNR) and spatial resolution before and after irradiation zSignal decrease starts at 2 x /cm 2  Resolution 11  m (before) to 7.4  m (after)  Measured on 50  m pitch strip detector

H. Pernegger, CERN, IPRD 2004, May 2004 New type of CVD diamond: CVD Single Crystals zMotivation: Avoid defects and charge trapping present in pCVD diamonds uremove grain boundaries (homogeneous detector) uReduce (or eliminate) charge trapping zSignal distribution in a single crystal CVD diamond [Isberg et al., Science 297 (2002) 1670]

H. Pernegger, CERN, IPRD 2004, May 2004 Single Crystal CVD diamonds zHV and pumping characteristics zCurrent work with single crystals in cooperation with Element Six uImprove sample “engineering” (reduce variation) Full signal at 0.2 V/  m No pumping

H. Pernegger, CERN, IPRD 2004, May 2004 Single Crystal : Trancient Current Measurements (TCT) zMeasure charge carrier properties important for signal formation uelectrons and holes separately  Use  -source (Am 241) to inject charge zInjection  Depth about 14  m compared to 470  m sample thickness uUse positive or negative drift voltage to measure material parameters for electrons or holes separately uAmplify ionization current V  Electrons only Or Holes only

H. Pernegger, CERN, IPRD 2004, May 2004 Ionization current in a sample of scCVD diamond zExtracted parameters uTransit time uVelocity uPulse shape zTransit time of charge cloud uSignal edges mark start and arrival time of drifting charge cloud uError-function fit to rising and falling edge zTotal signal charge t_c

H. Pernegger, CERN, IPRD 2004, May 2004 Preliminary measurement of velocity on a single crystal zAverage drift velocity for electrons and holes  Extract  0 and saturation velocity   0 for this sample: uElectrons: 1714 cm2/Vs uHoles: 2064 cm2/Vs zSaturation velocity: uElectrons: cm/s uHoles: cm/s

H. Pernegger, CERN, IPRD 2004, May 2004 Preliminary carrier lifetime measurements zExtract carrier lifetimes from measurement of total charge zLifetime: >35 ns for electrons and holes -> larger than transit time zCharge trapping doesn’t seems to limit signal lifetime -> full charge collection (for typical operation voltages and thickness)

H. Pernegger, CERN, IPRD 2004, May 2004 Applications of CVD diamonds zIn general CVD diamond is used as detector material in several fields uHEP and nuclear phyics uHeavy ion beam diagnostics uSynchroton radiation monitoring  Neutron and  detection …. z(Short) Selection of Applications in this presentation uPixel detector developments using CVD diamond detector uBeam Conditions Monitoring (e.g. at LHC) uBeam diagnostics for radiotheraphy with proton beams

H. Pernegger, CERN, IPRD 2004, May 2004 Application I: Pixel Detectors with ATLAS & CMS FE chips zUse present implementation of radhard FE chips together with pCVD (later possible scCVD) diamonds zBumpbonding yields ≈ 100% now

H. Pernegger, CERN, IPRD 2004, May 2004 Preparation of pixel test assembly zTest assemblyzUnderbump metalization SiLab/ Bonn

H. Pernegger, CERN, IPRD 2004, May 2004 Example: FE chip with pCVD diamond zSource & Testbeam results with pCVD diamond mounted to Atlas Pixel chip M. Keil / SiLab/ Bonn  Spatial resolution (pad size = 50x400  m)

H. Pernegger, CERN, IPRD 2004, May 2004 Application II: Beam Conditions Monitoring z“DC current” uUses beam induced DC current to measure dose rate close to IP uBenefits from very low intrinsic leakage current of diamond uCan measure at very high particle rates zSimple DC (or slow amplification) readout zExamples: zSee talk by M.Bruinsma for BaBar uSimilar in Belle uSimilar method planned for CMS zSingle particle counting uCounts single particles uBenefits from fast diamond signal uAllows more sophisticated logic coincidences, timing measurements uUsed at high particle rates up to zRequires fast electronics (GHz range) with very low noise zExamples uCMS and Atlas Beam conditions monitor zCommon Goal: measure interaction rates & background levels in high radiation environment zInput to background alarm & beam abort

H. Pernegger, CERN, IPRD 2004, May 2004 Beamloss scenario: study for CMS (1) zE.g. accidental unsynchronized beam abort uInstantaneous, difficult to protect against Unsynchronised beam abort: ~10 12 protons lost in IP 5 (CMS) in 260ns (M. Huhtinen, LHC Machine Protection WG, Oct. 2003)

H. Pernegger, CERN, IPRD 2004, May 2004 Beamloss scenario: study for CMS (2) zE.g. Loss of protons on collimators close to experiments (“TAS”) uWorse in dose rate (>up to 1000 x unsynchronized abort if consecutive bunches are lost) uSlower (several turns) therefore possible to protect against if early signs are detected (dose [Gy]) (M. Huhtinen, LHC Machine Protection WG, Oct. 2003)

H. Pernegger, CERN, IPRD 2004, May 2004 CMS tests with Cern PS fast beam extraction Single pulses from diamond Bias on Diamond = +1 V/um Readout of signal: 16m of cable no electronics 20dB attenuation on signal cable (factor 10) Almost identical diamond response to PS beam monitor response (pulse length 40ns) Diamond signal current is 1-2 A ! 2 Diamonds PS beam monitor A. MacPherson et al. / CMS-BCM

H. Pernegger, CERN, IPRD 2004, May 2004 Atlas Beam Conditions Monitoring zTime-Of-Flight measurement to distinguish collisions from back ground during normal running zLocated behind pixel disks in pixel support tube Time difference 12ns Need to measure single MIPs radiation hard! … and very fast: rise time <1ns, width <3ns

H. Pernegger, CERN, IPRD 2004, May 2004 Atlas BCM: single-MIP detector with <1ns rise time 90 Sr source or 5GeV/c pions (Pb collimator) Diamond on support Scintillator Different versions of FE electronics (Fotec/Austria) 500Mhz (40 dB) (2 stages) 1 Ghz (60 dB) (3 stages) 2 pCVD diamond detector back-to-back w =360 µm, CCD ~ 130 µm HV Bias 2V/  m Source tests and test beam

H. Pernegger, CERN, IPRD 2004, May 2004 Preliminary test results zMIP signal (testbeam & Sr90 source) uafter 16m of cable uperpendicular to beam, double diamond assembly uRise time 900ps, FWHM = 2.1ns SNR = 7.3:1 preliminary

H. Pernegger, CERN, IPRD 2004, May 2004 Application III: Diamonds in Proton Therapy: Conventional X-Ray Therapy Ion-Therapy C-Ions 1 cm Protons 1 cm zAustrian medical accelerator facility zCancer treatment and non-clinical research with protons and C-ions

H. Pernegger, CERN, IPRD 2004, May 2004 Facility Layout Synchrotron 2 Experimental rooms 4 Treatment rooms Injector Preliminary layout zProton & Carbon Beam u Energy: MeV protons and MeV/u C-ions u Intensity: 1x10 10 protons (1,6 nA) and 4x10 8 C-ions (0,4 nA) u Beam size: 4x4 mm 2 to 10x10 mm 2 zDiamonds used for Beam Diagnostics: zHigh-speed Counting of single particles in extraction line zResolve beam time structure

H. Pernegger, CERN, IPRD 2004, May 2004 Testbeam results for Proton Beam Diagnostics z2 diamond with different pad size + scintilator as “telescopes” tested at Indiana University Cyclotron Facility  2.5 x 2.5 mm2 (in trigger) CCD = 190  m, D= 500  m  7.5 x 7.5 mm2 (for analog measurements) CCD = 190  m, D= 500  m triggermeasured

H. Pernegger, CERN, IPRD 2004, May 2004 Signal timing properties zAverage pulse shape zSingle shot zRise time : 340ps Duration: 1.4ns

H. Pernegger, CERN, IPRD 2004, May 2004 Signal/Noise and energy dependence zMeasured most probable S/N ranges from 15:1 to 7:1 200 MeV 104 MeV 55 MeV SNR Signal energy dependence

H. Pernegger, CERN, IPRD 2004, May 2004 Summary zCVD diamonds as radiation hard detectors  High quality polycrystalline CVD diamonds (ccd up to 270  m) are readily available now in large sizes uRadiation tests showed radiation hardness up to 2 x p/cm 2 zSingle crystal CVD diamonds promise to overcome limitations of polycrystalline CVD diamonds uFull signal collection already at lower voltages uLong charge lifetime uVery little charge trapping and uniform detector (no grain boudaries) zThere are many applications around which benefit from diamond’s intrinsic properties uStrip or Pixel detectors for future high luminosity accelerators uBeam diagnostics and monitoring

H. Pernegger, CERN, IPRD 2004, May 2004 High-bandwidth amplifier for fast signal measurements zUse current amplifier to measure induced current uBandwidth 2 GHz uAmplification 11.5 uRise time 350ps zInputimpedance 45 Ohm zReadout with LeCroy 564A scope (1GHz 4Gsps) zCorrect in analysis for detector capacitance (integrating effect) zCross calibrated with Sintef 1mm silicon diode   e = 1520 cm2/Vs uI = 3.77 eV +/- 15%

H. Pernegger, CERN, IPRD 2004, May 2004 Irradiation studies: Pions up to 2.9 x /cm 2 zSignal (or SNR) and spatial resolution before and after irradiation z50% Signal decrease at approx 3 x /cm 2 * (TO BE CONFIRMED) zNarrower signal distribution after irradiation z25% Resolution improvement Preliminary results