Post on 14-Jan-2016
description
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
for application in exotic atoms researches
Experimental requirements Experimental requirements
Experimental requirements
Exotic atom
e.m. position
of K line
(keV)
(eV)
(eV)
Required precision
(eV) (eV)
hydrogen 6.46 160 200 ~ 5 ~ 10
deuterium 7.81 500 800 ~ 25 ~ 100
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
500
600
700
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
SDD FWHM=140eV shap =1sSi(Li) FWHM=180eV shap =15s PIN diode FWHM=750eV shap =20sCCD FWHM=140eV frame=1s
Spectroscopic resolution: detector comparison - 2
Measure of the line shift – ideal case *
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
* No background contribution considered
222222 )245()140()200( eVeVeVFWHMFWHMFWHM SDDlinemeas
eVeV
N
FWHM
phot
meas 3.16000
10035.2/
%1160
3.1
eV
eV
shiftPeak
Background reductionBackground reduction
hIK
IA
h
tIA
tdr max
Timing with the anode signal
10-2
10-1
100
101
10-8
10-7
10-6
10-5
Area (cm2)
Tdr
ift (
s)
Drift time vs. Active area
A=0.1cm2 Tdrift = 70ns
A=0.5cm2 Tdrift =350ns
A= 1cm2 Tdrift =700ns
With: = 2k/cmH = 450m
Timing resolution with SDD
2
2
HN
A
qTdrift
Dn
s
Triggered acquisition
Kaontrigger
Concidencewindows
Detectedpulses
Consideredpulses
Kaon trigger X-ray pulseBackground pulse
dr max
Background reduction with triggered acquisition
=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
2000
3000
Co
un
ts
SDD # 1
1400 1600 1800 2000C ha nne ls
0
1000
2000
3000
Co
un
ts
SDD # 2
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 3
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 4
1400 1600 1800 2000C ha nne ls
0
1000
2000
3000
Co
un
ts
SDD # 5
1400 1600 1800 2000C ha nne ls
0
1000
2000
3000
Co
un
ts
SDD # 6
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 7
600 800 1000 1200 1400C ha nne ls
0
400
800
1200
1600
2000
Co
un
ts
SDD # 8
1400 1600 1800 2000C ha nne ls
0
1000
2000
3000
Co
un
ts
SDD # 9
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 10
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 11
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 12
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
tsSDD # 13
1000 1200 1400C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 14
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 15
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 16
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 17
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
SDD # 18
1400 1600 1800 2000C ha nne ls
0
500
1000
1500
2000
2500
Co
un
ts
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
• 65 rings, 1 cm2 area• 280m high-resistivity + 12m epi-layer
detector presently under test at Politecnico di Milano
Preliminary measurements
0 20 40 60 80 100Voltage [V ]
-1E-9
0E+0
1E-9
2E-9
3E-9
4E-9
Cur
rent
[A]
Leakage current ~ 3 nA @ room T
-60 -40 -20 0Voltage [V ]
-1 .2E-5
-8.0E-6
-4.0E-6
0.0E+0
Cur
rent
[A]
Voltage divider threshold voltage ~ -50V for 8 rings ( 65 rings biasshould be feasible with ~ - 400V)