Development of Diamond Detector at CNS 2011Jan 12

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

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

Spectrometers at RIBF will be equipped with 3 spectrometers: Zero. Degree 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

SHARAQ spectrometer n SHARAQ = Spectroscopy with High-resolution Analyzer of Radio. Active Quamtum beams q n Big. RIPS × High-resolution Beamline × SHARAQ spectrometer n Big. RIPS provides High intense RI beam n High-Resolution beamline realizes dispersion-matching transport against large momentum spread of RI Beam n SHARAQ spectrometer analyzes momentum of reaction products with high resolution Diamond is a key detector for obtaining high-intense tracking and high timing resolution.

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 2 nd target to measure neutron energy 3. Tracking detector for intense beam over 1 MHz Our DD was designed as a timing detector Goal : Time resolution ~ 10 ps

Why Diamond ? n Outstanding properties of Diamond q q q Extreme mechanical hardness and extreme high thermal conductivity Broad optical transparency in region from IR to UV n Insensitive for visible light Diamond is a semiconductor (band gap = 5. 47 e. V) and very high resistivity at room temperature (1016 Wcm) n No cooling and No p-n junction ⇒ Easy operation High charge carrier mobility (e: 2200/h: 1600 cm 2/Vs) n Fast rise time of detector signal High energy needed to remove carbon atom from the lattice (80 e. V) n Radiation hardness

Why Diamond ? n Diamonds materials we can use q Single-crystal CVD diamond plate n Maximum size: 5× 5 mm 2, d=50, 100, 200, 300 mm (commercially) q Polycrystalline CVD diamond plate n Maximum size: 50× 50 mm 2, d=50, 100, 200, 300 mm (commercially) n Development of large size of Polycrystalline CVD DD q Beam spot size : ~ 10× 30 mm 2 at the F 3 achromatic focus q Energy loss in the detector is large for heavy ions: ⇒ d. E/dx ~ 100 ke. V/mm ~ 105 e-h/mm (12 N 250 A Me. V) obtain the number of e-h pair to overcome the S/N ratio.

Development of Diamond detector q 2010/Apr. q Start the operation studies of diamond detector by using 10× 10 mm 2 DD (DD of early stage, given by Munich) q q Start the CNS-MSU collaboration q n n n Producing of large size of DD 2 plates of CVD diamond detector (30× 0. 2 mm 3) 2010/Apr. -Jul. q Discussions the electrode design with MSU q Test of Munich DD by using an alpha source (241 Am) 2010/Oct. 12 N beam bombarded a 10 mm-square DD 2010/Nov. -2010/Dec. q Evaporation of electrodes on 30 mm-squre diamonds q Signal check of DDs at MSU 2011/11/Jan. q A diamond detector was delivered from MSU. q n Test of Preamp and pulse processing

Diamond detectors Diamond detector of 10× 10 mm 2 Diamond detector of 30× 30 mm 2 This is used for studies of basic DD operations by using Alpha source and RI beams Arrived at CNS yesterday

Producing of large-size DD by collaboration with CNS and MSU n n n CNS prepared p. CVD diamond plates MSU made electrodes on diamond. Design are discussed together

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

Design for higher timing-resolution DD n Design goal of DD timing resolution : 10 ps q 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 1 2 5 5 3 4 5 6 10 7 9 10 11 12 8

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

Diamond signals by 5. 4 -Me. V alpha - Condition of DD 10 mm-square DD HV: +500 V Pre. Amp: DBA-IV (G ~ 50 d. B) Noise level: ~ 20 m. V (p-p) Signal: ~ 90 m. V a +HV Osc. 1 GHz We can obtain signals from both side of Diamond detectors

Diamond signals by 5. 4 -Me. V alpha Typical signal shape (DBA-IV) Rise time ~500 ps Pulse width ~1. 9 ns (FWHM)

Diamond signals by 180 A Me. V 12 N Setup Beam DD PL - Condition of DD 10 mm-square DD HV: 360 V Pre. Amp: DBA-IV (G ~ 50 d. B) Noise level: ~ 10 m. V (p-p) Signal: ~ 30 m. V HV Osc. 500 MHz Diamond (Pre. Amp out) Plastic Beam DD Vacuum

Property of 10 mm-square DD Charge collection depth = How thick can electrons (holes) be collected Q = 2. 6 p. C Diamond (Pre. Amp out) Based on - preamp gain (50 d. B) - num. of e-h by energy loss (13 e. V/e-h pair) Estimated Charge Collection Depth is ~ 10 micron. (~5% of generated e-h pairs. ) CCD of First-stage p. CVD diamond detectors is reported to be 12 micron. Recent p. CVD DDs are improved and reported to be ~200 micron. We are expecting this value for large-size DD.

Signal rate of DD by an alpha source. 10 mm-square DD + Preamp CVIDEC Noise level < 10 m. V / Typical pulse height ~30 m. V Thre -9. 2 m. V Leak current of DD I ~ 100 n. A At 600 V, count rate seems not to be saturated. Due to small CCD, electric field is not enough to collect all charges in diamond.

Stability in long-time operation 10 mm-square DD + Preamp CVIDEC HV = -300 V, Noise level < 10 m. V After set HV=0 Thre -9. 2 m. V Long time operation decreases pulse height of signals. After HV off, count rate was almost recovered.

Preamplifiers for optimized to DD n Requirement for Preamplifier q q n Broadband amplification (up to ~ 2 GHz) High gain (>40 d. B) and good S/N ratio because of small charge signals. Preamplifiers for DD in commercial q q 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

Comparisons of Preamplifiers DBA-IV CIVIDEC Fuji-Diamond Non-invert Coupling AC AC Bandwidth 3 M-2 GHz 100 k-1. 8 GHz 10 k-2. 5 GHz Gain 10 --50 d. B (controllable) 40 d. B 46 d. B 55 d. B Iwatsu -2. 5 k~+2. 5 k. V HV -600~+100 V Input/Output Impedance. 50/50 W Noise Level (p-p) 30 m. V 5 m. V 20 m. V ?

Next step of development n Beam time for 30 mm-square DD q q q 2011/Jan. /22 -24 ( 48 hours ) 8. 8 A Me. V Alpha beam at E 7 B beam line. Points should be checked n n n 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)

DD developing beam time n Detector setup and electronics

Summary n Study of basic operation of p. CVD diamond detector. q Check point for p. CVD DD n n n Manufacturing of large DD by CNS-MSU collaboration q q n Charge collection depth. Pulse decreasing effect in long-time operation. Size: 30× 0. 2 mm 3 Design for achieve good time resolution. One detector delivered, Beam study will be performed next weekend. Diamond detector will be installed for experiments in FY 2011.

Collaborators n n 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