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Development of Diamond Detector at CNS

Development of Diamond Detector at CNS. 2011/Jan./12 Shin’ichiro Michimasa (CNS). Contents. Motivation Physics attacked by using diamond detectors Basic property of diamond material Producing of diamond detectors by CNS-MSU collaboration Fundamental test of diamond detectors

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Development of Diamond Detector at CNS

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  1. Development of Diamond Detector at CNS 2011/Jan./12 Shin’ichiro Michimasa (CNS)

  2. Contents • Motivation • Physics attacked by using diamond detectors • Basic property of diamond material • Producing of diamond detectors by CNS-MSU collaboration • Fundamental test of diamond detectors • Operation of Diamond detector • Comparison of preamplifiers • Next step of development • Summary

  3. Spectrometers at RIBF RIBF will be equipped with 3 spectrometers: ZeroDegree spectrometer (Kubo, RIKEN) multi-purpose completed in 2007 SAMURAI spectrometer (Kobayashi, Tohoku Univ.) large acceptance, multi-particle will complete in 2011 SHARAQ spectrometer (Univ. of Tokyo) high resolution, rotatable completed in 2008

  4. SHARAQ spectrometer • SHARAQ = Spectroscopy with High-resolution Analyzer of RadioActive Quamtum beams • BigRIPS × High-resolution Beamline × SHARAQ spectrometer • BigRIPS provides High intense RI beam • High-Resolution beamlinerealizes dispersion-matching transport against large momentum spread of RI Beam • SHARAQ spectrometeranalyzes momentum of reaction products with high resolution • Diamond is a key detector for obtaining high-intense tracking and high timing resolution.

  5. Physics Motivation Physical Programs with SHARAQ and Diamond detectors (DD) 1. Mass measurement by combining TOF and Brho. ⇒ High-timing resolution to achieve TOF 2. (p,n) measurement in inverse kinematics. ⇒ Timing-start counter installed near the 2nd target to measure neutron energy 3. Tracking detector for intense beam over 1MHz Our DD was designed as a timing detector Goal : Time resolution ~ 10 ps

  6. Why Diamond ? • Outstanding properties of Diamond • Extreme mechanical hardness and extreme high thermal conductivity • Broad optical transparency in region from IR to UV • Insensitive for visible light • Diamond is a semiconductor (band gap = 5.47eV)and very high resistivity at room temperature (1016Wcm) • No cooling and No p-n junction ⇒ Easy operation • High charge carrier mobility (e: 2200/h: 1600 cm2/Vs) • Fast rise time of detector signal • High energy needed to remove carbon atom from the lattice (80 eV) • Radiation hardness

  7. Why Diamond ? • Diamonds materials we can use • Single-crystal CVD diamond plate • Maximum size: 5×5 mm2, d=50,100,200,300mm (commercially) • Polycrystalline CVD diamond plate • Maximum size: 50×50 mm2, d=50,100,200,300mm (commercially) • Development of large size of Polycrystalline CVD DD • Beam spot size : ~ 10×30 mm2 at the F3 achromatic focus • Energy loss in the detector is large for heavy ions: ⇒dE/dx ~ 100 keV/mm ~ 105 e-h/mm (12N 250A MeV) obtain the number of e-h pair to overcome the S/N ratio.

  8. Development of Diamond detector • 2010/Apr. • Start the operation studies of diamond detector by using 10×10 mm2 DD (DD of early stage, given by Munich) • Test of Preamp and pulse processing • Start the CNS-MSU collaboration • Producing of large size of DD2 plates of CVD diamond detector (30×30×0.2 mm3) • 2010/Apr.-Jul. • Discussions the electrode design with MSU • Test of Munich DD by using an alpha source (241Am) • 2010/Oct. • 12N beam bombarded a 10mm-square DD • 2010/Nov.-2010/Dec. • Evaporation of electrodes on 30mm-squre diamonds • Signal check of DDs at MSU • 2011/11/Jan. • A diamond detector was delivered from MSU.

  9. Diamond detectors Diamond detector of 10×10 mm2 Diamond detector of 30×30 mm2 This is used for studies of basic DD operations by using Alpha source and RI beams Arrived at CNS yesterday

  10. Producing of large-size DDby collaboration with CNS and MSU • CNS prepared pCVD diamond plates • MSU made electrodes on diamond. • Design are discussed together

  11. Diamond materials for Detector Data sheet of Diamond material Uniformity of thickness is controlled precisely

  12. Design for higher timing-resolution DD • Design goal of DD timing resolution : 10 ps • Need to timing correction by hit-positions.Speed of signals on electrode : ~1.6 mm / 10 ps Face A (timing information) Face B (HV suppied) 10 9 10 1 2 4 3 5 6 5 5 8 10 7 12 11

  13. Operation study by using small DD • We study the properties of a DD. • Signal shape of DD • Charge collection depth • Long-time stability • Basic experience to operate large-size DD.

  14. a +HV Osc. 1GHz Diamond signals by 5.4-MeV alpha • Condition of DD • 10mm-square DD • HV: +500 V • PreAmp: DBA-IV (G ~ 50dB) • Noise level: ~ 20 mV (p-p) • Signal: ~ 90 mV We can obtain signals from both side of Diamond detectors

  15. Diamond signals by 5.4-MeV alpha Typical signal shape (DBA-IV) Rise time ~500 ps Pulse width ~1.9 ns (FWHM)

  16. Diamond signals by 180A MeV 12N Setup • Condition of DD • 10mm-square DD • HV: 360 V • PreAmp: DBA-IV (G ~ 50dB) • Noise level: ~ 10 mV (p-p) • Signal: ~ 30 mV Beam DD PL HV Osc. 500MHz Diamond (PreAmp out) Plastic Beam DD Vacuum

  17. Property of 10 mm-square DD Charge collection depth = How thick can electrons (holes) be collected Q = 2.6 pC Diamond (PreAmp out) Based on - preamp gain (50dB) - num. of e-h by energy loss (13 eV/e-h pair) Estimated Charge Collection Depth is ~ 10 micron. (~5% of generated e-h pairs.) CCD of First-stage pCVD diamond detectors is reported to be 12 micron. Recent pCVD DDs are improved and reported to be ~200 micron. We are expecting this value for large-size DD.

  18. Signal rate of DD by an alpha source. 10mm-square DD + Preamp CVIDEC Noise level < 10 mV / Typical pulse height ~30 mV Thre -9.2mV Leak current of DD I ~ 100 nA At 600V, count rate seems not to be saturated. Due to small CCD, electric field is not enough to collect all charges in diamond.

  19. Stability in long-time operation 10mm-square DD + Preamp CVIDEC HV = -300 V, Noise level < 10 mV After set HV=0 Thre -9.2mV Long time operation decreases pulse height of signals. After HV off, count rate was almost recovered.

  20. Preamplifiers for optimized to DD • Requirement for Preamplifier • Broadband amplification (up to ~ 2GHz) • High gain (>40dB) and good S/N ratio because of small charge signals. • Preamplifiers for DD in commercial • DBA-IV (DBA series, developed at GSI) • CIVIDEC Broadband preamplifier • High frequency preamplifier by Fuji diamond Co.Ltd. (developed by KEK) • Broadband preamplifier by Iwatsu

  21. Comparisons of Preamplifiers Fuji-Diamond Iwatsu CIVIDEC DBA-IV Non-invert Non-invert Non-invert AC AC AC Coupling AC 3M-2GHz 1M-2GHz Bandwidth 100k-1.8GHz 10k-2.5GHz 10--50dB (controllable) 40dB 46dB 55dB Gain -2.5k~+2.5kV HV -600~+100V Input/Output Impedance. 50/50 W 50/50 W 50/50 W 50/50 W Noise Level (p-p) ? 5 mV 20 mV 30 mV

  22. Next step of development • Beam time for 30mm-square DD • 2011/Jan./22-24 ( 48 hours ) • 8.8A MeV Alpha beam at E7B beam line. • Points should be checked • Charge collection depth • Timing resolution • Detection efficiency (coincidence with plastic scinti.)as a function of HV • Charge information of signals • Intensity dependence • (Long-time stability)

  23. DD developing beam time • Detector setup and electronics

  24. Summary • Study of basic operation of pCVD diamond detector. • Check point for pCVD DD • Charge collection depth. • Pulse decreasing effect in long-time operation. • Manufacturing of large DD by CNS-MSU collaboration • Size: 30×30×0.2 mm3 • Design for achieve good time resolution. • One detector delivered, • Beam study will be performed next weekend. • Diamond detector will be installed for experiments in FY2011.

  25. Collaborators • S.Michimasa, M.Takaki, K.Kisamori, H.Miya,S.Go, S.Ota, E.Ideguchi, T.Uesaka, S.Shimoura (CNS)for SHARAQ collaboration • A.Stolz, R.Zegers, M.Sasano (NSCL/MSU) Thank you for your attention

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