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SIDDHARTA the future of exotic atoms research at
DAFNE Silicon Drift Detector for Hadronic
Atom Research by Timing Applications   DAFNE-2
004 Physics at meson factories Mihai
Iliescu INFN-LNF 10-06-2004
   
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The goal of KH and KD measurements a few eV
determination of both shift and width of the 1s
level induced by the strong interaction in the
Kp and KD atomic systems The main feature to deal
with, in order to obtain the desired accuracy,
is the S/B ratio. This requires to pass from 170
(KH today) to at least 11 (KH) and 15 (KD-first
time)
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Experimental requirements for the
measurements a triggerable, large area, high
resolution, high efficiency in the energy region
of interest (1-20 KeV) X-ray detector
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Triggerable SDDs A large area Silicon Drift
Detector (SDD), equipped with trigger
electronics, presently under development (SIDDHAR
TA project), satisfies the experimental
requirements
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Working principles of the SDD
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The classical PIN (Positive-Intrinsic-Negative)
diode detector
Entrance window
ANODE
The anode capacitance is proportional to the
detector active area
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The Semiconductor Drift Detector
The electrons are collected by the small
anode, characterised by a low output capacitance.
Anode
Advantages very high energy resolution at fast
shaping times, due to the small anode
capacitance, independent of the active area of
the detector
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The Silicon Drift Detector with on-chip JFET

• JFET integrated on the detector
• capacitive matching Cgate Cdetector
• minimization of the parasitic capacitances
• reduction of the microphonic noise
• simple solution for the connection
  detector-electronics in monolithic arrays
• of several units

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The integrated JFET
Detector produced at Max-Planck-Institute for
Extraterrestrial Physics, Garching, Germany
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Performances of the SDDs
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Silicon Drift Detector QE and resolution
Quantum efficiency of a 300 mm thick SDD
55Fe spectrum measured with a SDD (5 mm2) at
10C with 0.5 ms shaping time
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Spectroscopic resolution detector comparison - 1
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Spectroscopic resolution detector comparison - 2
FWHMmeas of monoenergetic emission line 5.9
keV 1cm2 detector at 150 K SDD FWHM140eV tshap
1ms Si(Li) FWHM180eV tshap 15ms PIN
diode FWHM750eV tshap 20ms CCD
FWHM140eV tframe s
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Timing resolution with SDD
A0.1cm2 ? Tdrift 70ns A0.5cm2 ? Tdrift
350ns A 1cm2 ? Tdrift 700ns
With r 2kW/cm H 450mm
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Timing with the anode signal
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Triggered acquisition
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Background reduction with triggered acquisition
Machine Background NK number of detected kaons
per detected Ka X-ray 103Br background rate
103 events/s over 200 cm2, full spectrum (1-20
KeV) --gt50 Hz/1KeV Tw gate window Tw NK x
Tdrift max 103 x 1 ms 1ms B Br x Tw 50
s-1 x 10-3 s 5 x 10-2 S/B20/1
negligible Hadronic background (Kp-pS
interaction, synchronous) preliminary simulation
(typical SDD thickness 300 mm) S/B 5/1 (KH),
1/4 (KD)
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SDD test setup electronics layout
P.S.
Temp. control
SDD canister
7 Shapers, peak stretchers discriminators
HV control
Amplified SDD output signal
Stretcher reset
DAQ
Analog output
Discrim. output
Shapers control motherboard
Trigger (NIM logic)
NIM 2 TTL
Trigger signal
Scintillators
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Test of the 30 mm2 SDD
Detector biasing parameters
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T - 40C, tsh0.75ms
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SIDDHARTA setup version 1
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SIDDHARTA setup version 2
SDDs array
Beam pipe
e-
e
Kaon trigger
Cryogenic target cell
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Kaon stopping distribution inside hydrogen target
for a toroidal setup
Signal 30 times more than in DEAR
Kaons stopped inside target 30 (all generated)
MonteCarlo simulation
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SIDDHARTA Kaonic hydrogen simulated spectrum
MonteCarlo simulation
Precision on shift 1 eV
integrated luminosity 60 pb-1
S/B 5/1
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SIDDHARTA Kaonic deuterium simulated spectrum
Precision on shift lt 10 eV
S/B 1/4
MonteCarlo simulation
integrated luminosity 100 pb-1
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SIDDHARTA collaboration LNF, Frascati
(Italy) MPE, Garching (Germany) PNSensor, Munich
(Germany) Politecnico, Milan (Italy) IMEP, Vienna
(Austria) IFIN-HH, Bucharest (Romania)
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Conclusions
Results obtained with DEAR and evaluations done
for SIDDHARTA show that DAFNE represents an ideal
machine for hadronic atoms research Continuing
tests on detectors to obtain best performance
prototype, compatible with a large area
setup. Finalizing the design of the new
experimental setup front-end electronics,
mechanics, cryogenics, vacuum
2006 Assembly on DAFNE and data taking