Space Applications: Overview
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Transcript of Space Applications: Overview
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September 15, 2006 R.P. Johnson 1
Space Applications: OverviewSpace Applications: Overview
Robert P. Johnson
Santa Cruz Institute for Particle Physics
Physics Department
University of California at Santa Cruz
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September 15, 2006 R.P. Johnson 2
OutlineOutline• Tracking detectors
– Pamela
– AMS
– Agile
– GLAST
• Compton telescopes– MEGA
– ACT
– Si/CdTe concept (see earlier talk by Shin Watanabe)
• Focal-plane detectors—well covered later in this session and also in early sessions– Ground based (see talk by Richard Stover in this session)
– LSST (see talk by Steve Kahn in this session)
– JDEM/SNAP (see talk by Chris Bebek in this session)
– MAXI (see talk by Hiroshi Tsunemi in this session)
I will restrict this talk to the use of silicon-strip tracking systems in space. There are by now several examples of HEP-like experiments built for operation in orbit.
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PamelaPamela
Cosmic-ray spectrometer; antimatter search.
Permanent magnet: ~0.4 T
Measure antiprotons up to 190 GeV.
Silicon-strip tracker.
Launched earlier this summer from Baikonur.
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PamelaPamelaPamela completed its instrument checkout in early July and is now taking science data.
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Pamela Silicon-Strip TrackerPamela Silicon-Strip Tracker• Double-sided, double metal, AC-
coupled• 6 planes of 3 ladders each• 300 m thick; 7.0×5.3 cm2 area• 50 m readout pitch• 4 m resolution in bending plane,
15 m in the non-bending plane• 90% efficiency per plane for MIP
• VA1 chip used for readout
• 62 W power consumption
• ~ 3 mW/channel
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Alpha Magnetic SpectrometerAlpha Magnetic Spectrometer• Cosmic-ray
spectrometer.• Antimatter search.• Dark matter search.• Superconducting
magnet (0.97 T).• Silicon-strip tracker.
Complex particle physics detector for operation in orbit!
Destined for the completed space station, which makes its schedule very uncertain at this time.
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AMS Silicon-Strip TrackerAMS Silicon-Strip Tracker• Double-sided, 300 m thick silicon strip detectors.
• Arranged in 8 layers on 5 support planes; 192 ladders (6.45 m2 of Si).
• AC coupled to VA-hdr9a chips via capacitor chips (700 pF).
• (1284+384)×192=320,256 readout channels.
• 10 micron resolution in bending plane (30 micron out of plane).
• 734 W/320,256=2.3 mW of power per channel (~0.7 mW/ch in the VA chip).
• Active cooling with CO2.
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AMS Silicon-Strip TrackerAMS Silicon-Strip Tracker• Honeycomb support plane with ladders installed on the top side.
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AGILEAGILE• Gamma-ray (pair-conversion tracker), with about 4 m2 of Si strips
• Hard X-ray imaging (coded mask)
• To be launched on a PSLV rocket from the Sriharikota base in India – Currently held up by U.S. State Dept. (mindless ITAR issue)
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AGILE Tracker/ConverterAGILE Tracker/Converter• Single sided SSDs, AC coupled, 9.5×9.5 cm2, 410 m thick
• 121 m strip pitch; 242 m readout pitch; 38-cm long strips in ladders
• Analog readout by the 128-channel TAA1 chip (IDEAS)– 0.4 mW/channel in front end
• 36,864 readout channels in 24 layers (12 x,y pairs)
• Silicon ladders bonded to top and bottom of composite “trays”
• 0.7 X0 tungsten converter foils on the bottom surfaces of the top 10 trays
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Super AGILESuper AGILE• Hard x-rays (15 to 45 keV)• Silicon-strip plane placed 14-cm below a coded tungsten mask• 6 arc-minute angular resolution, from 121 m strip pitch• 19-cm long silicon strips read by XAA1.2 chips; 410 m thick• 6144 channels
Collimator
SSDs
Coded Mask
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Super AGILESuper AGILE• 30 pF channel• Sensitivity: ~0.01 Crab in a 14-hour exposure• Energy resolution ~5 keV FWHM • 300 cm2 effective area on axis (~20% of the geometric area)
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GLAST Large Area TelescopeGLAST Large Area TelescopeSi Strip Tracker/Converter
– 36 single-sided Si layers
• 228 m pitch; 400 m thick
• 8.95 cm square SSDs
• AC coupled
– 16 tungsten layers
– 884,736 channels
– 160 W
– Self triggering
Fairly large HEP detector to operate in orbit:• 3 ton mass (allocated)• ~ million channels• 3 detector subsystems• 5 computers• But only 650 Watts (allocated)!
• 74 m2 of Si in the flight instrument• About $8 per square centimeter
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GLAST SSD Tracker/Converter
Flex-Circuit Readout Cables
36 Multi-Chip Electronics Modules (MCM)
2 mm gap between x,y SSD layers
19 Carbon-Fiber Tray Panels
Titanium Flexure Mounts
Carbon-Fiber Sidewalls (Aluminum covered)
• Carbon-composite structure supports 18 x and 18 y layers of silicon-strip detectors and 16 layers of tungsten converter foils.
• 36 custom readout electronics boards, each with 1536 amplifier channels, mount on the sides of the panels to minimize inter-tower dead space.
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Tracker Mechanical Fabrication Challenges
Top view of 4 Tracker Modules
MCM
1 Tracker Tray
Right-angle interconnect
Very tight space for electronics
High precision carbon-composite structure to maintain 2.5 mm gaps between modules
X-section of tray edge
Tray
Sidewall
<18 mm from active Si to active Si!
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GLAST Tracker ElectronicsGLAST Tracker Electronics
ASIC based, for minimum power (180 W/ch).
Digitize on chip:
No coherent noise or pedestal variation!
Single threshold (0 or 1).
ToT on trigger OR.
Internal calibration system.
Threshold & Cal DACs.
Redundant 20 MHz serial control and readout paths.
4 event buffers at front end negligible deadtime (few s).
GTFE ASICGTRC ASIC
Direct descendent of the BaBar ATOM-based FE system (UCSC/LBNL/INFN).
0.5 m CMOS
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GLAST Tracker StatusGLAST Tracker Status16+2 towers completed.
Flight array fully integrated in completed LAT.
Environmental testing completed at NRL.
Delivery to General Dynamics this month.
Two spare towers in beam testing at CERN.
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GLAST Tracker Performance
• Hit efficiency (in active area) >99.4%
• Overall Tracker active area fraction: 89.4%
• Noise occupancy <5×107
• (with small number of noisy channels masked)
• Power consumption 158 W (178 W/ch)
• Time-over-threshold 43% FWHM
Muon time-over-threshold (OR of all channels per layer)
Threshold variation <9% rms in all modules
(5.2% on average)
Strip #, 1 to 1536Strip #, 1 to 1536
Hit efficiency from cosmic-ray muonsHit efficiency from cosmic-ray muons
1 example readout module1 example readout module
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Cosmic-Ray Gamma Conversions in 8 Towers
Launch in autumn 2007
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Compton TelescopesCompton Telescopes• Two general concepts have been competing for the next
generation detector, to improve upon Comptel:– Classic: measure energy loss, direction, and total energy– e tracking: add measurement of the electron direction
• Also capable of fully measuring pair conversions.– 3-Compton: measure 1 scattering angle and 2 energy losses
Classic:Comptel
3-Compton:ACT, NCT, LXeGRIT
e tracking:MEGA,TIGRE
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NRL Advanced Compton TelescopeNRL Advanced Compton Telescope• 7 mm thick Si (Li
drifted) detectors (alternative to Ge)
• ~300 V bias
• 1010 cm2 wafers
• 4×4 arrays, stacked 24 deep
• Cooled to 40C• 4 of these towers
are proposed for the complete instrument
• Improve on the Comptel sensitivity by factor of ~100
See also the talk in this conference by Mark Amman on the alternative Ge strip detectors.
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MEGAMEGA
Prototype:– 11 layers of 3×3 array of 6-cm square wafers, each 500 m thick.– 470 m strip pitch– 1 cm spacing between layers– calorimeters with 0.5-cm square CsI scintillators, 8-cm deep, with PIN diode
readout
Satellite concept:– 32 silicon layers– 6×6 array of 6-cm wafers in
each layer– calorimeter surrounding the
lower hemisphere, 8-cm thick on the bottom and 4-cm thick on the sides
– drift diode readout– Good sensitivity from 0.5 MeV
to ~100 MeV, using both Compton scattering and pair conversion.
See also the talk by Shin Watanabe (Si/CdTe Compton telescope concept) in this conference for another interesting example.
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ConclusionConclusion• We are starting to see HEP-like solid-state tracking detectors
put into orbit, with 105 to 106 channels.– AMS-1 (shuttle flight) and Pamela (in orbit)
– AGILE and GLAST are close to launch
• The detector systems and DAQ are relatively simple or small compared with state-of-the-art ground-based detector systems, but the environment (rocket ride, power, thermal, QA) is challenging.– Many lessons learned by these groups that could/should be applied
to future projects
• There is a lot of scientific and technical interest in a large Compton telescope, but unfortunately no major mission in sight at this time.