Recent progress of PureCsI+APD readout 2009 July 7th Natsuko Maeda/Kenkichi Miyabayashi （Nara Women’s University） Belle-II calorimeter meeting

Outline Introduction Set up of cosmic test. Results 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 Active area : 1cm×1cm. Quantum Efficiency 35~40% @300nm. Typical gain : 50. 波長[nm] 量子効率[%] 100 50 300 900 600 20 PMT APD 1200 CsI BGO GSO NaI Q.E. S8664-1010 (Taken from Hamamatsu web page) wavelength Taken from Dr. J.Kataoka’s ppt

Counter preparation Preamp Real size pure CsI Small board with APD (optical contact:grease) HV line Signal cable

Set up of cosmic test Cosmic ray Digital Oscilloscope (ch.1) APD Analog out Shaper (30ns) FADC (12bits,43MHz) Pure CsI Preamp. CAMAC module HV Digital Oscilloscope (ch.2: trigger). Coincidence

They are inside thermostatic box. Triggers … kept at 25 deg.C. 7

An cosmic event example on the oscilloscope 8

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 July Aug. Sep. Oct. Nov. Dec. L.O. by small sample Rad. Hard. by small sample. Tomoko Iwashita Start up.(?) Event generation & anal. G4 (simple) simulation L.O. check (&Rad. Hard.) Belle-II General Meeting 2X2X20cm3 4pieces test.prod. KM HV supply system, Monitor system, etc., Mechanical structure (crash test as well?) Cosmic test PureCsI+APD Temp., HV, … Cosmic test Ref.BSO+APD Seek further improve, Test temp.-feedback HV. Natsuko Maeda As of 20090707