Recent progress of PureCsI+APD readout

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

2. 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

3. 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.

4. 100 BGO GSO 量子効率[%] NaI APD CsI 50 20 PMT 0 300 600 900 1200 波長[nm] Hamamatsu S8664-1010 APD • Active area : 1cm×1cm. • Quantum Efficiency 35~40% @300nm. • Typical gain : 50. Q.E. S8664-1010 (Taken from Hamamatsu web page) wavelength Taken from Dr. J.Kataoka’s ppt

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

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

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

8. An cosmic event exampleon the oscilloscope 2μs

9. 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.

10. Fit to obtain pulse height Test Pulse n=5; shaper circuit a=pulse height t0=pulse start time =timescale Pedestal

11. Pulse height spectrum for test pulse Noise level is obtained to be ~8 FADC counts.

12. Same thing repeated; cosmic data A typical event + Pedestal

13. Cosmic pulse height spectrum PureCsI+S8664-1010 HV=455V Average pulse height obtained to be ~120 FADC counts.

14. 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.

15. 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.

16. 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.

17. Items & schedule toward decision 2009 Dec. in KM’s mind 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