Status of CsI for Background Run

1
Status of CsI for Background Run
Achim Stahl DESY Zeuthen
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The CsI(Tl) Crystals

• Properties
• light yield 70.000 ph. / MeV
• temp. coeff. 0.1 / oC
• peak emission 565 nm
• decay time 940 nsec
• index of reflection 1.79
• density 4.51 g/cm3
• radiation length 1.86 cm
• Molière radius 3.8 cm
• soft material / slightly hygroscopic
• dimensions 5 x 5 x 30 cm3
• weight 4 kg
• doping Thallium 100 p.p.m

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Lightyield
Our test crystal 4000 p.e. / MeV (1 diode)
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Uniformity
Our test crystal 4000 p.e. / MeV (1 diode)
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Uniformity
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Crystals for Background-Run
2 crystals from BABAR testbeam run _at_ PSI
Supplied by Univ. of Dresden
Old crystals, probably low lightyield
Surfaces repolished
? ready for use
310 mm
3 test crystals 50x50x10 mm3
? first results
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2 Options
Light Readout Diode PreAmp
Light Readout PMT
PMT
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Diode Option
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The Photodiodes
Si pin-diodes Hamamatsu S7244-08
active area 1cm x 2cm, 2 diodes per crystal
spare diodes for BABAR
supplied by Univ. of Dresden
premounted on 1mm polystyrene plate
wrapping 2 layers Tyvek ? keep 1 layer Al-foil
? Cu-foil 1 layer Mylar
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Preamplifier
spare BABAR preamps
design Dieter Freytag / SLAC
supplied by SLAC
2 channels per preamp board (for the 2 diodes)
180 nsec shaping time (timing energy
resolution)
calibration circuitry (currently not used)
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Shaping Amplifier
BABAR readout scheme
non-linearity lt 0.1
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Shaping Amplifier
UMass board
diff
charge- integrating ADC diff. input
diff
diff
diff
diff
diff
shaping 180 nsec
shaping 400 nsec
BABAR module test stand
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Shaping Amplifier
UMass board
receiver
charge- integrating ADC
diff
diff
uni-pol.
x 1
uni-pol.
diff
x 1
diff
x 1
x 1
shaping 180 nsec
shaping 400 nsec
E166
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Shaping Amplifier
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Electronics Layout
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ADCs
5 GeV / 100 keV / 32 ? dynamic range 2000 ?
11-bit ADC

• SLAC LeCroy 2249 W
• CAMAC Q-ADC
• 11-bit
• Zeuthen CAEN V265
• VME Q-ADC
• 12-bit resolution
• 15 bit dynamic range

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Mechanics
frame finished output connector due this week
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RF-Shields Grounding
key to low noise !
connector
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Signals
50 mV / div
few 100 nsec puls
one of our first signals seen high int. LED on
diode
LED
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Signals
large cosmics signal
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Noise
241Am source (a ?) 60 keV ? line 16500
electrons in Si ? width ? noise
diode
1000 1500 electrons noise 1 diode
gate 1 µsec 2.3 µsec BABAR 1200 electrons
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Cosmics Spectrum
test crystal
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Source Spectrum
source
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Source Spectrum
Si(Li) detector
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Source Spectrum
source
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Status
Xtal ready Mechanics ready (except for
connector) DiodePreamp working reasonable
light yield good noise performance UMass
board working housing to be done Receiver
still to be done ADC need to decide
Satisfactory results with test crystal
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PMT Option
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Mechanics
all materials in hand work started this
week expect 4 weeks total
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PMT XP2020

• very fast 2 tube
• 12 stages, lin. focused
• borosilicate window
• bi-alkali cathode
• typ. gain 107
• max. gain 2 108
• pulse width 2.4 nsec

20 tubes available
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Elektronics Layout
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Dynamic Range
XP2020 max. anode current 280 mA (2
non-linearity)

• reduce gain
• reduce coupling
• use signal from 1st dynode

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Range Switching
LED
source calibration PMT directly attached to
crystal
XP 2020
CsI
LED pulser to measure change in coupling
LED
XP 2020
CsI
data taking air gap reduces coupling to crystal
air gap
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Cosmics Spectrum
crystal
XP2020
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a-Spectrum
XP2020
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Status
Xtal ready Mechanics ready in 4
weeks Readout available and working LED
monitor to be done Tests minimum
gain modify base ? test with GeV
signals ADC need to decide Satisfactory
results with test crystal
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AOB

• source for calibration
• reasonably dry lab-space
• desicant (recycle?)
• power supplies from SLAC?
• 8V for PreAmp / UMass board
• 60 V bias for diodes
• 3000 V for PMT
• trigger electronics

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Man-Power CsI
DESY Zeuthen Hermann Kolanoski Achim Stahl Sabine
Riemann Klaus Mönig PhD-stud Karim Laihem
start 1.12.03
Humboldt-University Thomas Lohse Nikolaj
Pavel IngTech Michael Jablonski Postdoc Thomas
Schweizer (25 )
DESY Hamburg Postdoc Roman Pöschl
(50 )
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Outlook
Diode Option ready in 2 weeks (4
weeks with final receiver)
PMT Option ready in December
Testbeam still in December ?

• Many Thanks to BABAR !
• SLAC
• Univ. of Dresden
• U. Mass.

The End