DEAR SDD --> SIDDHARTA DEAR SDD --> SIDDHARTA Si Si licon licon D D rift rift D D etector for etector for H H adronic adronic A A tom tom R R esearch and esearch and T T iming iming A A pplications pplications Carlo Fiorini Carlo Fiorini (Politecnico di Milano) (Politecnico di Milano) Development of a soft X-ray detection apparatus, based on Silicon Drift Detectors (SDD), with high energy resolution and high background reduction for application in exotic atoms researches
DEAR SDD --> SIDDHARTA Si licon D rift D etector for H adronic A tom R esearch and T iming A pplications Carlo Fiorini (Politecnico di Milano) Development of a soft X-ray detection apparatus, based on Silicon Drift Detectors (SDD), with high energy resolution - PowerPoint PPT Presentation
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DEAR SDD --> SIDDHARTADEAR SDD --> SIDDHARTA
SiSilicon licon DDrift rift DDetector foretector for H Hadronic adronic AAtom tom RResearch and esearch and TTiming iming AApplicationspplications
Carlo FioriniCarlo Fiorini(Politecnico di Milano)(Politecnico di Milano)
Development of a soft X-ray detection apparatus,based on Silicon Drift Detectors (SDD),
with high energy resolution and high background reduction
Working principles of the SDDWorking principles of the SDD
n
n+
p+ -V cc
The classical PIN diode detector
The anode capacitance is proportional to the detector active area
n
n+
p+ -V cc
p+
The Semiconductor Drift Detector
AnodeThe electrons are collected by the small anode,characterised by a low output capacitance.
Advantages: very high energy resolution at fast shaping times, due to the small anode capacitance, independent of the active area of the detector
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
The integrated JFET
Detector produced at the MPI Halbleiterlabor, Munich, Germany
Performances of the SDDsPerformances of the SDDs
Quantum efficiency of a 300 m thick SDD 55Fe spectrum measured with a SDD (5 mm2) at –10°C with 0.5 s shaping time
Silicon Drift Detector performances
Silicon Drift Detector Droplet or SD3
T=-30°C a τsh=1µs
5000 5500 6000 6500 7000EN ER G Y [eV ]
0
2000
4000
6000
8000
CO
UN
TS
Fe55
K
K
FW HM =131 eV
Canode= 50 fF
(vs. 100fF conventional SDD)
Resolution in the line shift measurementResolution in the line shift measurement
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1100
200
300
400
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800
A (cm-2)
FW
HM
(eV
)
SDD PIN Si(Li) 150 K 5.9 keV line
PIN Tsh=20us
Si(Li) Tsh=20us
SDD Tsh=1us
Spectroscopic resolution: detector comparison - 1
FWHMmeas of monoenergetic emission line 5.9 keV1cm2 detector at 150 K
The case: kaonic hydrogen, 200 cm2 detection systemFor 6000 events (~ 50 pb-1 )Estimated peak position 6.3 keV, line width about 245 eV, peak shift about 160 eVDetection system based on SDDs
=number of detected kaons per detected X-ray = 103
Br=background rate = 103 events/s
Tw=sinchronization window
Tw = r x drift max = 103 x 1 s = 1ms
B = Br x Tw = 103 s-1 x 10-3 s = 1
S/B = 1/1
Actual value of the S/B ratio measured with DEAR at DANE
using CCDs
S/B 1/100 in kaonic hydrogen
expected:
S/B 1/500 in kaonic deuterium
Signal/Background with CCD
hIK
IA
Timing with the prompt signal from the backplane
IA
IK
h
t
t
tdr maxEstimated time resolution: about 300 ns
Reliability of the detection set upReliability of the detection set up
1400 1600 1800 2000C ha nne ls
0
1000
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3000
Co
un
ts
SDD # 1
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Co
un
ts
SDD # 2
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un
ts
SDD # 3
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un
ts
SDD # 4
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un
ts
SDD # 5
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un
ts
SDD # 6
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un
ts
SDD # 7
600 800 1000 1200 1400C ha nne ls
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un
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SDD # 8
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SDD # 9
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SDD # 10
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SDD # 11
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un
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SDD # 12
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Co
un
tsSDD # 13
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un
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SDD # 14
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un
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SDD # 15
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un
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SDD # 16
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un
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SDD # 17
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SDD # 18
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SDD # 19
Monolithic array of Silicon Drift Detectors
Pixel area = 5 mm2
Total array area = 95 mm2
DEAR test setup (SDD) at the BTF
BTF e+/e - beam
e+, e – shower
Pb plateTi foil
Zr foil
SDD X-ray detector (4 chips prototype)
Pb shielding
S2
X-ray lines
S1
scintillators
Operations:
The first stage of the project of the new detector deals with the characterization of the SDD performances.
The characterization concerns the finalization of trigger efficiency and energy resolution, as a function of background environment and time window. This information will fix also the dimension of the single cell. These measurements are planned to be performed with a prototype device. The answers coming from these tests will be used for the construction of the final detector array and associated electronics with optimal characteristics.
Beam conditions at BTF:
Energy: varying between 50 ÷ 750 MeV
Intensity: varying between 1÷ 103 e+/e- s-1 (preference is for positrons)
bunch : 10 ns; bunch frequency: 1 ÷ 49 Hz
Gate window 0.1 – 1 s
BTF run period required:
2-4 weeks in the period June 2003 - October 2003
The detector: 1 cm2 SDD prototype
Front-side: field strips, JFET Back-side: entrance window