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L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
P.Ubertini, L.Natalucci, E.M. Quadrini and collaborators
IASF/INAF
b [deg]
l [deg]
INTEGRAL: coded mask FOV and source multiplicity
INTEGRAL/IBIS map of Cassiopeia region (20-50 keV)
mosaic 0.7-1.6 Ms, 0.4 – 12 mCrab, den Hartog et al. 2005
SPI
IBIS
XMM (30’)HMXB
SNR
AXP
ms-pulsar Diffuse emission (26Al, 60Fe)from Gal plane
Many different source types – outside GC and bulge !
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
• The high energy sky is highly variable and ToO’s are important
© M. Revnivtsev & E. Churazov, IKI Moscow/MPA Garching
3 deg
GC region, 17-60 keV, 12 frames (36 days)GC region, 17-60 keV, 12 frames (36 days)
The transient gamma-ray sky
Sources can appear in ~1000s
Or a few days
Or a few weeks
Rev 169 Rev 171
Sguera et al., 2005 A&A, in press
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
• CdZnTe pixellated detectors (energy band ~3-300 keV), which can be assembled in very compact, modular configuration
• Use of coded mask technique
Very large area, high resolution instrument can be achieved by natural extension of the INTEGRAL/IBIS concept
with much wider FOV to ensure detection of a large number of transient events, such as ~100/y
BeppoSAX/WFC heritage
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
The stopping power of CdTe/CZT keV is dramatically higher than Si,Ge (45% at 200 keV, for 3mm thick detector
100 keV Absorption Efficiency
0,00
0,10
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0,30
0,40
0,50
0,60
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0 1 2 3 4 5 6 7 8 9 10
Thickness (mm)
Ab
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rbti
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Si Ge CdTe
CdTe/CZT units are also:
• operating at room temperature
• performing well in space environment (low activation, fast recovery after solar flares)
• small pixel manufacturing, pixel arrays
• mass production is relatively low cost, and established technologyCdTe/CZT vs other
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
• CZT detection plane with improved characteristics, achievable within ~ 2 years.
• Effort to achieve extended performance, like <0.5 keV resolution for detection of X-ray features during prompt emission of GRBs and transients.
• Up to 10000 cm2 can be achieved for the sensitive area if high energy range is limited to ˜ 300 keV
WFGC detector
• Power consumption is, in average, 0.5-1 mWatt per channel; total required: ≤ 100 W for the whole unit FEE.
the ISGRI MDU
the ISGRI “polycell”
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
CZT: technology improvements
Need to improve CZT performances compared to present available commercial products. The goal is to achieve a factor 5-10 better energy resolution:
Improvement areas:
• Crystal growth and composition
• Surface treatment and contact depositions
• Front end electronics
• Digital processing electronics
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
R & D program in Italy for CZT developmentA program has started with a consortium of institutes/industries (P.I. M.Quadrini):
• IMEM-CNR for crystal development
• INAF Milan, Bologna, Rome and Palermo:
Detector development incl. AFEE, DFEE
Signal elaboration, Data Processing
Instrument concept and models
• AAA-I-Laben for AFEE studies
• VENEZIA Tecnologie for evaluation of mass production
Funding from ASI expected. Program already started
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
• wide FOV (~2 sr) and moderate angular resolution (down to ~ 1-2 arcmin) to detect and localize transient events
• monitoring capability, but also detailed characterization of prompt emission, like GRBs, fast transients, bright source outbursts
• extension of the mission range from X-rays to higher energies
Schematic of a possible configuration for one WFGC unit
2004 concept
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
We had in the first instance, considered two possible solutions, based on 2 mm and 3 mm thick CZT, respectively.
The effective area for 2mm and 3mm detector thickness.
Effective area
The thickness of the tungsten mask will depend on the chosen CZT thickness.
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
a coded mask design for the WFGC could be based on MURA pattern, with 2.4 mm pitch. The mask pitch is about 1.5 times the size of the basic detector pixel.
The mask is placed 1m from detector.
Imaging (an exercise)
• the coding power is 80%
• the Point Source Location Accuracy, PSLA < 1 arcmin for a > 10sigma detection. The PSLA depends on the signal-to-noise: for this configuration, is expected to be about 1.5 arcmin at the source detection limit.
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
Main difference from 2004 design:Limit the energy range to <300 keV (no 511)
Option 1Less area more FoV (4 detectors with smaller area)
Option 2• Completely new instrument FoV structure: annular mask and detector (similar to the
one of GRI-ESA Cosmic Vision Study):• Area 5,000-10,000 cm2• Single annular modular detector concept• Thin annular mask (0.5-1 mm W) • Wide field around the X-Ray telescope for shorter slew, fast repointing, transient event
always within the WFC FoV.• No high energy calorimeter (4-300 keV)
Plus 10-60 s on-target, lighter package, full time history for each det GRB
Minus not easy design, need R&D for detector performance electronics
Others On board SW and S/C autonomous operability, TL M resources management
Possible improvement
CZT Wide Field Gamma-Camera for ESTREMO
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
Option 1.
up to 4 different units located aside on S/C support
Option 2. (schematic, top view)
detector modules positioned on “annulus” on a support platform, mask ~ 75 cm from detector, sensitive area 7700 cm2
support struct
S/C
Mask envelope
1m36 CZT modules
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
Sky coverage option 2
~130O
Exposed area in FOV
Circular FOV shape
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
MASS AND POWER BUDGET OPTION 1
W mask 30 kg 15kgTube/Hopper, W 70 20 CZT detection plane 40 40Calorimeter/Veto BGO 30 30Electronics 20 10Structure 20 12Harness 10 satellite Contingency 20 13
Total: 240 140 x 2 units = 280 Kg
Power Budget 100 W 100 W x 2 units = 200WMASS BUDGET OF VERSION 2 UNDER ESTIMATION
2004 Light version
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
Energy range: 4-200 keV without response up to 511 Sensitive area 2300 cm2 (48 x 48 cm2) Energy resolution: 1 % (E>60KeV) Sensitivity: 1 mCrab/day, 20 mCrab in 2000s
(HEO E>40 keV, Solar max) PSLA: 20 arcsec Nominal ang. Resolution 10 arcmin Field of View: 90 x 90 deg @zero response (~2 ster)
(> 50% coding for offset angles <35 deg)
Summary of scientific performances option 1
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
New class of fast transients associated to HMXBs
IBIS detects them very well! (Negueruela et al. 2005)
IGR J17544-2619
Chandra (int’Zand et al 2005)
At least up to 7 objects detected of this kind
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
CZT Wide Field Gamma-Camera for ESTREMO
New class of fast transients associated to HMXBs
XTE J1739-302 = IGR J17391-3021
IBIS/ISGRI “zooming” on source outburst (Sunyaev et al. 2003)
RXTE/PCA (Smith et al 2005)
L.Natalucci,WHIM Conference, Roma, 17-18 Jan 2006
High localization accuracy is essential in many cases, and most important with improving sensitivity
Sources in molecular cloud NGC6334, as seen by Chandra
ISGRI error box
Hard X-ray source identified as a background AGN
(Bassani et al., astroph/0510338)
CZT Wide Field Gamma-Camera for ESTREMO