Recent progress of PureCsI+APD readout 2009 July 7th Natsuko Maeda/Kenkichi Miyabayashi （Nara Women’s University） Belle-II calorimeter meeting Outline • Introduction – Motivation – Hamamatsu S8664-series APD. • Set up of cosmic test. • Results – Typical event – Pulse height spectrum – Equivalent noise energy • Further check points • Summary and plan Motivation • PureCsI+PhotoPentrode option (baseline) – Design based on the technologies as of 2002, 7 years ago. – Why not revisit recent progress of devices and materials? – Photon sensor; Large area(1cm2) APD. – Scintillating crystal; BSO→ separate talks. Hamamatsu S8664-1010 APD Q.E. • Active area : 1cm×1cm. • Quantum Efficiency 35~40% @300nm. 100 • Typical gain : 50. BGO 量 子 効 50 率 [%] GSO NaI APD CsI 20 PMT S8664-1010 (Taken from Hamamatsu web page) 0 300 600 900 1200 波長[nm] wavelength Taken from Dr. J.Kataoka’s ppt Counter preparation Real size pure CsI Small board with APD (optical contact:grease) Preamp HV line Signal cable Set up of cosmic test Cosmic ray Pure CsI Digital Oscilloscope (ch.1) APD Analog out Preamp. Shaper (30ns) HV Coincidence FADC (12bits,43MHz) CAMAC module Digital Oscilloscope (ch.2: trigger). They are inside thermostatic box. Triggers … kept at 25 deg.C. An cosmic event example on the oscilloscope 2μs How to obtain equivalent noise energy(E.N.E.) • Noise level in FADC counts; – Obtained by the width of the pulse height spectrum peak obtained by test pulse. • Energy scale determined by cosmic rays; – Transversely passing through M.I.P. ~30MeV. Fit to obtain pulse height Test Pulse n=5; shaper circuit a=pulse height t0=pulse start time =timescale Pedestal Pulse height spectrum for test pulse Noise level is obtained to be ~8 FADC counts. Same thing repeated; cosmic data A typical event + Pedestal Cosmic pulse height spectrum PureCsI+S8664-1010 HV=455V Average pulse height obtained to be ~120 FADC counts. Equivalent noise energy(E.N.E) • 30 MeV X (8/120) = 2 MeV. – Even 2 APDs are attached, down to 1.4 MeV. – Still significantly higher than required level. Further check points • Dependence on applied voltage, temperature, APD piece-by-piece variation to be measured. • S8664-1010 typically at 25 deg.C, – Gain X50 at ~420V. – Breakdown at ~470V. – Now 455V is applied. • long term stability test needed at such voltage. Summary and plan • PureCsI+APD(S8664-1010) cosmic test going. – 455V applied. – E.N.E. is ~2MeV; still higher than required. – HV, temperature dependence, piece-by-piece variation to be tested. • Same kind of test to be repeated with BSO. – Borrowed reference crystal; 2.2X2.2X18cm3. – Mechanical attachment to be designed/ordered soon. – Narrower trigger counters to be prepared as well. Items & schedule toward decision 2009 Dec. in KM’s mind L.O. by small sample Aug. Sep. Rad. Hard. by small sample. Oct. Nov. Tomoko Iwashita Start up.(?) Event generation & anal. G4 (simple) simulation L.O. check (&Rad. Hard.) 2X2X20cm3 4pieces test.prod. KM Mechanical structure (crash test as well?) Cosmic test Cosmic test PureCsI+APD Ref.BSO+APD Temp., HV, … HV supply system, Monitor system, etc., Dec. Belle-II General Meeting July Seek further improve, Test temp.-feedback HV. Natsuko Maeda As of 20090707
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