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 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

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. Hamamatsu S8664-1010 APD Active area : 1cm×1cm.
Quantum Efficiency
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. S
(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)
APD
Analog out
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. 7

8. An cosmic event example on the oscilloscope8

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+S
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.
S 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
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