Transcript detectors in missions for Aull

Hubble Space Telescope Cutaway
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Hubble Space Telescope Field of View
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WFC3
ACS
STIS
COS
FGS
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HST: WFC3
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HST: WFC3
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HST: ACS
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HST: ACS
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HST: STIS
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HST: STIS
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Spitzer Space Telescope
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IRAC
IRS
MIPS
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Spitzer Space Telescope: IRAC
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Spitzer Space Telescope: IRS
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Spitzer Space Telescope: MIPS
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Chandra Space Telescope
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ACIS
HRC
Spectral modes
Advanced Charged Couple Imaging Spectrometer (ACIS): Ten CCD chips in 2 arrays
provide imaging and spectroscopy; imaging resolution is 0.5 arcsec over the energy
range 0.2 - 10 keV; sensitivity: 4x10-15 ergs/cm2/sec in 105 s
High Resolution Camera (HRC): Uses large field-of-view mircro-channel plates to
make X-ray images: ang. resolution < 0.5 arcsec over field-of-view 31x31 arc0min;
time resolution: 16 micro-sec sensitivity: 4x10-15 ergs/cm2/sec in 105 s
High Energy Transmission Grating (HETG): To be inserted into focused X-ray beam;
provides spectral resolution of 60-1000 over energy range 0.4 - 10 keV
Low Energy Transmission Grating (LETG): To be inserted into focused X-ray beam;
provides spectral resolution of 40-2000 over the energy range 0.09 - 3 keV
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Chandra Space Telescope: ACIS
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Chandra Advanced CCD Imaging Spectrometer (ACIS)
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Chandra Space Telescope: HRC
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Chandra Space Telescope: Spectroscopy
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High Resolution Spectrometers - HETGS and LETGS
These are transmision gratings
– low energy: 0.08 to 2 keV
– high energy: 0.4 to 10 keV (high and medium resolution)
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Groove spacings are a few hundred nm.
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Gemini (North)
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Gemini (South)
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JWST
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NIRCAM
NIRSPEC
MIRI
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JWST: NIRCAM
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Nyquist-sampled imaging at 2 and 4 microns -- short
wavelength sampling is 0.0317"/pixel and long wavelength
sampling is 0.0648"/pixel
2.2'x4.4' FOV for one wavelength provided by two identical
imaging modules, two wavelength regions are observable
simultaneously via dichroic beam splitters.
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JWST: NIRSPEC
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1-5 um; R=100, 1000, 3000
3.4x3.4 arcminute field
Uses a MEMS shutter for the slit
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JWST: MIRI
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5-27 micron, imager and medium resolution spectrograph (MRS)
MIRI imager: broad and narrow-band imaging, phase-mask coronagraphy,
Lyot coronagraphy, and prism low-resolution (R ~ 100) slit spectroscopy
from 5 to 10 micron.
MIRI will use a single 1024 x 1024 pixels Si:As sensor chip assembly.
The imager will be diffraction limited at 7 microns with a pixel scale of
~0.11 arcsec and a field of view of 79 x 113 arcsec.
MRS: simultaneous spectral and spatial data using four integral field units,
implemented as four simultaneous fields of view, ranging from 3.7 x 3.7
arcsec to 7.7 x 7.7 arcsec with increasing wavelength, with pixel sizes
ranging from 0.2 to 0.65 arcsec. The spectroscopy has a resolution of
R~3000 over the 5-27 micron wavelength range. The spectrograph uses
two 1024 x 1024 pixels Si:As sensor chip assemblies.
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JWST: MIRI MRS
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NIRSPEC/Keck Optical Layout
Side View
NIRSPEC/Keck Optical Layout
Top View
Large CCD Mosaics
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LSST Has a Big Camera
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LSST Has a Big Focal Plane
Wavefront Sensors
(4 locations)
Guide Sensors
(8 locations)
3.5 degree Field of View
(634 mm diameter)
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History of Infrared Light Detection
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Herschel’s detection of IR from Sun in 1800
Johnson’s IR photometry of stars (PbS) mid 60’s
Neugebauer & Leighton: 2um Sky Survey (PbS), late 60’s
Development of bolometer (Low) late 60’s
Development of InSb (mainly military) early 70’s
IRAS 1983
Arrays (InSb, HgCdTe, Si:As IBCs) mid-80’s
NICMOS, 2MASS, IRTF, UKIRT, KAO, common-user
instruments, Gemini, etc.
• JWST and the search for cosmic origins
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Detector Size
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Applications
Imaging (single photon counting)
Figures Courtesy of Don Hall (University of Hawaii)
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Fermi Gamma-ray Large Area Space Telescope
(GLAST)
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GLAST LAT
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Gamma Ray Detection Airshowers
• It is possible to detect gamma rays by the presence of their byproducts produced in Earth’s atmosphere.
• Ground-based gamma ray telescopes actually detect
Cherenkov radiation emitted by high energy particles produced
through the interaction of the gamma rays and atmospheric
particles.
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Caltech Submillimeter Observatory (CSO)
• CSO has a 10.4m primary dish.
• SHARCII has 350, 450, 850um
passbands, 12x32, 2.6x1amin field.
• Dry nights lead to better sensitivity
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Stratospheric Observatory for Infrared Astronomy
(SOFIA)
• SOFIA has 2.5m mirror.
• It has a variety of instruments (see below) covering optical to FIR.
• HAWK is being upgraded with new detectors and polarimeters.
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Herschel
• The Herschel telescope is a Cassegrain
design with a 3.5m primary. The three
scientific instruments are:
– HIFI (Heterodyne Instrument for the
Far Infrared), a very high resolution
heterodyne spectrometer
– PACS (Photodetector Array Camera
and Spectrometer) - an imaging
photometer and medium resolution
grating spectrometer
– SPIRE (Spectral and Photometric
Imaging Receiver) - an imaging
photometer and an imaging Fourier
transform spectrometer
• Covers 60-670 um.
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Planck
• The Planck telescope has an offaxis 1.5m primary. The
scientific instruments are:
– LFI (Low Frequency Instrument),
a High Electron Mobility
Transistor based radio receiver.
– HFI (High Frequency Instrument),
a bolometer based imaging array
• Covers 300um to 1.2cm.
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ALMA
• The Atacama Large Millimeter/submillimeter Array
• Covers 300um to a few cm
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Radio Telescope Components
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Reflector(s)
Feed horn(s)
Low-noise amplifier
Filter
Downconverter
IF Amplifier
Spectrometer
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Antenna Fundamentals
• An antenna is a device for converting electromagnetic
radiation into electrical currents or vice-versa, depending on
whether it is being used for receiving or for transmitting.
• In radio astronomy, antennas are used for receiving.
• The antenna receiver usually receives radiation from a dish,
but it doesn’t have to.
• For instance, the Long Wavelength Array (LWA) that has
~104 dipoles. At a wavelength of 15m, the dipoles have ~106
m2 of effective collecting area, where collecting area goes as
wavelength squared, divided by 4 pi.
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Very Large Array (VLA)
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VLA Main Features
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27 radio antennas in a Y-shaped configuration
fifty miles west of Socorro, New Mexico
each antenna is 25 meters (82 feet) in diameter
data from the antennas are combined electronically to give the
resolution of an antenna 36km (22 miles) across
• sensitivity equal to that of a single dish 130 meters (422 feet)
in diameter
• four configurations:
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A array, with a maximum antenna separation of 36 km;
B array -- 10 km;
C array -- 3.6 km; and
D array -- 1 km.
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VLA Receivers
Receivers Available at the VLA
4 Band
P Band
L Band
C Band
X Band
U Band
K Band
Q Band
Frequency (GHz)
0.073-0.0745
0.30-0.34
1.34-1.73
4.5-5.0
8.0-8.8
14.4-15.4
22-24
40-50
Wavelength (cm)
400
90
20
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3.6
2
1.3
0.7
Primary beam (arcmin)
600
150
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5.4
3
2
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Highest resolution (arcsec)
24.0
6.0
1.4
0.4
0.24
0.14
0.08
0.05
1000-10,000.K
150-180.K
37-75.K
44.K
34.K
110.K
50-190.K
90-140.K
System Temp
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Very Long Baseline Array (VLBA)
• ten radio telescope antennas
– 25 meters (82 feet) in diameter and weighing 240 tons
– Mauna Kea to St. Croix in the U.S. Virgin Islands
• VLBA spans more than 5,000 miles, providing astronomers
with the sharpest vision of any telescope on Earth or in space.
• efforts to reduce funding
• efforts to increase sensitivity (~6x)
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Chandra
Originally AXAF
Advanced X-ray
Astrophysics Facility
http://chandra.nasa.gov/
Chandra in Earth orbit (artist’s conception)
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Chandra Orbit
• Deployed from Columbia, 23 July 1999
• Elliptical orbit
– Apogee = 86,487 miles (139,188 km)
– Perigee = 5,999 miles (9,655 km)
• High above LEO  Can’t be Serviced
• Period is 63 h, 28 m, 43 s
– Out of Earth’s Shadow for Long Periods
– Longer Observations
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Chandra Mirrors Assembled and Aligned by Kodak
in Rochester
“Rings”
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Mirrors Integrated
into spacecraft at
TRW (NGST),
Redondo Beach, CA
(Note scale of telescope
compared to workers)
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Chandra ACIS CCD Sensor
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