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Roma Jan.2006 WHIM and mission opportunities Wide Field Monitor Prospect for use of Silicon and scintillator detectors Based on work made at: IASF - INAF.

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Presentation on theme: "Roma Jan.2006 WHIM and mission opportunities Wide Field Monitor Prospect for use of Silicon and scintillator detectors Based on work made at: IASF - INAF."— Presentation transcript:

1 Roma Jan.2006 WHIM and mission opportunities Wide Field Monitor Prospect for use of Silicon and scintillator detectors Based on work made at: IASF - INAF Sezione di Bologna IASF - INAF Sezione di Milano IASF - INAF Sezione di Roma ENEA FIS Bologna Politecnico di Milano, Dpt. Elettronica e Inf. Università di Pavia, Dpt. Ing. Elettronica PNSensor GmbH München

2 Roma Jan.2006 WHIM and mission opportunities Wide Field Monitor What may be requested to it? Primarily: Sensitivity (to transient events) FOV coverage Angular resolution Extended energy range Eventually: Energy resolution Time resolution Coded mask system coupled to a position sensitive detector plane

3 Roma Jan.2006 WHIM and mission opportunities Building blocks for the detector plane Why scintillators ? א Many materials available with various characteristic of density, velocity, light output. א May be shaped in many forms and size א Consolidated technology א New appealing materials with improved spectroscopic capabilities Can directly compete in performances with solid state detector

4 Roma Jan.2006 WHIM and mission opportunities array with CsI(Tl) elements 0.03 x 0.03 x 2cm in size Volume: 2 10 -4 cm 3 AGILE MiniCalorimeter detector elements CsI(Tl) 1.5 x 2.3 x 37.5 cm in size Volume: 1.3 10 2 cm 3

5 Roma Jan.2006 WHIM and mission opportunities Building blocks for the detector plane Why Silicon Photodetectors? ك High QE (90%) for visible light ك Si technology allows many device design focussed on low noise level (SDC-PD), or speed (avalanche or PIN PD) ك Can be used as detector for visible photon or directly for low energy X-rays ك Naturally suited for array architectures (small, ligth, rugged, etc..)

6 Roma Jan.2006 WHIM and mission opportunities The Silicon Drift Chamber The collecting anode capacitance is very small (> 0.1 pF) and independent from the device area very low noise readout

7 Roma Jan.2006 WHIM and mission opportunities SDC as direct X detector Range: >.6 30 keV active area10 mm2 Si thickness300 mm JFETembedded E threshold0.6 keV E resolution @ 20°C 5% FWHM @5.9 keV (0.5 sec sh. time)0.9% FWHM @ 60 keV Noise (ENC)45 e - rms @ 20°C 241 Am 55 Fe

8 Roma Jan.2006 WHIM and mission opportunities SDC coupled to a scintillator Range: 15 1000 keV crystal CsI(Tl) light yield25 - 38 e - /keV E threshold< 16 keV efficiency80% @ 200 keV (1 cm crystal) 25% @ 1 MeV energy resolution4.8% FWHM @ 662 keV at room temperature 137 Cs

9 Roma Jan.2006 WHIM and mission opportunities Prototype SDC-PD: as they look like studies on Bonding on ceramic support Passivation SDC Materials for optical coupling SDC area ~10 mm 2 Top view Bottom view 1.2 cm

10 Roma Jan.2006 WHIM and mission opportunities One unique detector for extended energy range X-ray interacts in Si delivering a fast charge pulse : (< 10 ns) -ray pass throug Si and interact in CsI(Tl) delivering a slow pulse: (few s) The identification of the interaction type will be done with a Pulse Shape Discrimination (PSD) technique Main Characteristics: – Low energy threshold (~2 keV) – Extended energy range (related to crystal thickness) – Excellent energy resolution M. Marisaldi, IEEE Trans. NS Vol 51, No 4, 2004, p. 1916 SiCsI(Tl) X Direct detection in Si Scintillation light detection SDDscintillator

11 Roma Jan.2006 WHIM and mission opportunities Fast vs slow component Am-241 In the plane fast-slow channel the two operation modes (X, ) are well defined in two row with different r = Channel fast / Channel slow In Si: r = 0.92 In CsI: r = 0.54

12 Roma Jan.2006 WHIM and mission opportunities Pulse Shape Discrimination (PSD) Factor of merito M 100% PSD possible when M > 1.5 100% PSD for E>3.6 keV in Si and E>35 keV in CsI PSD still possibile per E>1.5 keV in Si and E>16 keV in CsI lower noise and greater light yield –––> lower PSD limit 6.7 - 17 keV in Si 70 - 180 keV in CsI

13 Roma Jan.2006 WHIM and mission opportunities PSD limit vs Temperature 25 °C: 4.5 keV in Si, 46 keV in CsI M=1.5 10 °C: 2.0 keV in Si, 18 keV in CsI 0 °C: 1.7 keV in Si, 15 keV in CsI -20 °C: 1.0 keV in Si, 7 keV in CsI

14 Roma Jan.2006 WHIM and mission opportunities How much to cool? Threshold in CsI cooling at 10 °C is enough to fill the efficiency gap between Silicon and the crystal

15 Roma Jan.2006 WHIM and mission opportunities Mixed interactions With PSD it is possible to discriminate mixed interactions in Si and CsI Mixed events can be rejected,or corrected 60 keV in CsI + I KL and Cs KL X-rays in Si: r~0.87 26 keV in Si: r=0.92

16 Roma Jan.2006 WHIM and mission opportunities Wide field monitor design Coded mask instrument Example of a monitor that can be realised with already available components: pixel size d=3.6 mm detector size D=400 mm mask size M=800 mm mask-destector focal length l=1 m fully coded FOV = 43.6° FWHM = 77.3° (1.4 sr) angolar resolution = 18 point source localisation = 3.5 at 5 number of pixels: 12000.

17 Roma Jan.2006 WHIM and mission opportunities Gamma flash sensitivity Integral flux for 3 different GRB (,, E p spectral parameters, Band D. et al., 1993, ApJ 413, 281). Solid : =-1, =-2. Dashed: =-0.5, =-2. Dot-dashed: =-1, =-3. Faintest detectable burst (1-1000 keV), from Band, D., (2003) ApJ 588, 945 Trigger range 20 - 1000 keVTrigger range 1.5 - 40 keV SDC/scintillator detectors cover, in an unique instrument an energy band over 3 order of magnitude. The spectroscopic capabilities of SDC allow a continuing monitoring of a detected burst during the pointing of the narrow field instruments.

18 Roma Jan.2006 WHIM and mission opportunities Further scientific revenues from a Wide Field Monitor with an extended energy range Transient studies: A monitor working on an extended Energy range can be used to study strong absorbed sources like that one found by INTEGRAL. Monitoring of known sources: If the monitor FOV is large enough it can be possible the monitoring of the timing and spectral variability of known sources GRB studies: A wide energy band can be a benefit on the studies of GRB Cosmic Background: Like SAX-PDS a monitor with good sensitivity can be used for CB studies

19 Roma Jan.2006 WHIM and mission opportunities Technical challenge: number of pixel X and with exploding number of channels PICsIT-INTEGRAL (2002): 4.096 ch TRACKER AGILE (2006): 46.000 ch GLAST even more Read-out electronic chain using very large integration techniques with: Whole analogue chain suitable for spectroscopy Many embedded logical function to harmonize the behaviour of different detector in an unique array Low power consumption, miniaturisation, Latch-up e SEU immunity Use of Application Specific Integrated Circuits (ASIC) with mixed analogue- digital technology is mandatory.

20 Roma Jan.2006 WHIM and mission opportunities HERITAGE: ICARUS ASIC 16 channels each one with: charge-preamp, shaping amplifier discriminatorpeak & hold Multiplexercommand logic power: 8 mW/ch noise:950 e- rms For PIN PD e CsI(Tl) 256 chip on PICsIT-INTEGRAL ASIC for SDC ICARUS footprint 16 channe/ASIC: I/F to SDD shaping amplifier discriminator peak & hold Multiplexercommand logic power: 8 mW/ch noise:60 e- rms For SDC: 2 possibilities: 8 ch for X-ray detection 8 ch for CsI(Tl) RUA ASIC 1 prototype built each channel with: I/F to detector shaping amplifier discriminatorpeak & hold ADCI/F Noise with SDC: > 50 e- rms Can be used for many different detectors ASIC for electronic read-out

21 Roma Jan.2006 WHIM and mission opportunities RUA prototype RUA layout Chip Area 13.7 mm 2 Channel Area3.3 mm 2 Digital output10 bits # of programmable reg.47 Programmable parameters Amp. gain1, 2, 5, 10 Peaking time0.5, 1, 3, 6 µs Pole-zero correction0.1, 0.2, 0.5, 1, 2 ms Polarity+ / - Fine gain1 ÷ 2 with 10-bit Threshold 1.5 V ÷ 1.7 V with 8-bit Rise time protection1, 2, 5, 8, 10 µs

22 Roma Jan.2006 WHIM and mission opportunities RUA Shaper programmability Variuos peaking time programmable with RUA

23 Roma Jan.2006 WHIM and mission opportunities Possible improvement: new materials New Lanthanum composites recently available LaBr3(Ce)LaCl3(Ce) CsI(Tl) Density g/cm35.293.79 4.51 Decay time ns2628600 - 3400 Light yield ph/keV6349 50 Light yield vs NaI(Tl) %13070-90 45 Wavelength of max em nm350380 560 Hygroscopicyesyes no Res.FWHM @661 keV %2.83.8 8 (with PMT)

24 Roma Jan.2006 WHIM and mission opportunities New materials: can be used with SDC? Yes if a wavelength shifter is used between crystal and PD Estimated Energy resolution FWHM @ 661 keV vs efficiency of light collection in the SDC (noise SDC considered 50 e- rms) PSD for use of both Si and crystal at the same time may be still possible: need To Be Investigated (%) Res @ 661 keV 501.7 302.3 104.6


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