Transcript PowerPoint - X-ray Astronomy Group at ISAS

Hakucho (1979)
Tenma (1983)
to be launched on Feb. 8th, 2000
Ginga (1987)
ASCA (1993)
ISAS
Institute of Space and Astronautical Science
The Astro-E mission is the fifth in a series
of Japanese X-ray astronomy missions,
following the Hakucho, Tenma, Ginga
and ASCA satellites. It is scheduled to be
launched on Feb. 8th 2000 by the M-V
launch vehicle from Kagoshima Space
Center (KSC), Japan.
Astro-E features excellent sensitivity, with
high throughput over an unprecedented
wide energy band from 0.5 keV to 600
keV. This wide bandpass, combined with
high resolution spectroscopic capabilities,
makes Astro-E a unique tool capable of
addressing a wide variety of fundamental
subjects in astrophysics, involving the
origins of elements and structures in the
Universe as well as the evolution and
dynamics of these structures.
Astro-E
5.4 m
6.5 m
Total Weight 1670 kg
Development of Astro-E
Astro-E was developed at Japan’s
Institute of Space and Astronautical
Science (ISAS) in an extensive
collaboration between scientists from
Japan and the United States.
International Collaborations
•X-ray Telescope (XRT)
[Nagoya Univ., NASA/GSFC, ISAS]
•X-ray Micro-calorimeter (XRS) [ISAS, NASA/GSFC, Univ. of Wisconsin,
Tokyo Metropolitan Univ., Riken]
•X-ray CCD (XIS)
[Kyoto Univ., Osaka Univ., ISAS, MIT]
•Hard X-ray Detector (HXD)
[Univ. of Tokyo, ISAS, RCNP]
•Operation and Data processing [ISAS, NASA/GSFC]
Astro-E’s Instruments
Astro-E carries five X-Ray Telescopes (XRTs). These telescope
modules provide the soft X-ray images on the focal-plane
instruments. One telescope module (XRT-S) feeds the X-ray
Spectrometer (XRS); the other modules (XRT-I) have X-ray
Imaging Spectrometer (XIS) units at their focal planes. At the
same time, the Hard X-ray Detector (HXD) measures highenergy (hard) X-rays.
XRT-I
XRT-S
HXD
XIS
XRS
Extendible Optical
Bench (EOB)
6.5m
The focal length of the telescope is
4.75 m for the XIS and 4.5 m for the
XRS. These telescopes are mounted
on an extendible optical bench.
Because of the limited length available
within the rocket nose fairing, the
optical bench is “telescoped” inside
the space craft during the launch and
will be extended by 1.5 m in orbit to
achieve the proper focal lengths.
Astro-E Satellite
(photo by ISAS)
(photo by ISAS)
Astro-E’s Orbit
Astro-E will be, first, put into a transfer
orbit of ~250 km perigee and ~550 km
apogee. After three DV operations at
apogee, the final orbit will be approximately
circular with ~550 km altitude and ~31
degree inclination.
• 180 deg attitude maneuver
• Spin up
• Satellite Separation
perigee up
X-ray Space Observatories in the New Millennium
Effective Area of High Resolution Instruments
Astro-E Instruments
XRT-S + XRS
XRT-I + XIS
HXD
Energy range
0.4-12 keV
0.5 - 12 keV
10-600 keV
Effective area
190 cm2
1300 cm2
160cm2 (<30 keV) 330cm 2 (>40 keV)
Focal Length
4.5 m
4.7 m
HPD of PSF
2'
2'
12 eV at 6 keV
120 eV@ 6 keV
3.5 keV @ 10 keV ~9% @ 662 keV
1.9' x 4.2'
19' x 19'
0.56 x 0.56 ° @< 100 keV
Energy resolution
Field of view
4.6 x 4.6 ° @>200 keV
Pixel size
0.94' x 0.24'
1.1" x 1.1"
Number of pixels
2 x 16
1024 x 1024
Time resolution
30μsec
8 ms - 8 sec
30.5 - 61 μsec
X-ray Telescopes (XRT)
Astro-E X-ray telescopes consist of
nested conical thin-foil mirrors
based on a similar design concept
to the ASCA telescopes, but with
several improvements. The half
power-diameter (HPD) is better than
ASCA's by about a factor of two.
The ratio of the focal length to the
diameter is smaller, making the
grazing angles smaller. This leads
to better reflectivity for higher
photon energies. The focal lengths
of 4.5 m for the XRS and 4.75 m for
the XIS give effective areas of ~500
cm2 at 1.5 keV and ~300 cm2 at 8
keV for a single telescope.
(Photo by ISAS)
[Nagoya Univ., NASA/GSFC, ISAS]
The effective area of XRTs
The effective area of XRTs for Astro-E,
ASCA, XMM and Chandra .
Astro-E XRT
Area:
2 x ASCA at 7keV
HPD
2 arcmin
(ASCA 3.6 arcmin)
XMM
Astro-E(4XIS)
ASCA(4)
Astro-E
(XRS)
Chandra
XRT Final Configuration on the satellite
XRT-S
XRT-I
(photo by ISAS)
X-ray Spectrometer (XRS)
The XRS is a cryogenic X-ray detector
system utilizing a microcalorimeter
array of 32 pixels operating at 60 mK.
An energy resolution of about 12 eV at
6 keV is obtained across the array.
The micro calorimeter array employed
in the XRS is the first such instrument
to fly in a satellite. Over broad range of
energies, ~0.4 to 12 keV, it has an
unprecedented energy resolution of 814 eV. XRS allows us to study chemical
composition and dynamics of cosmic
hot plasmas to the highest level, never
achieved in the past.
[ISAS, NASA/GSFC, Wisconsin Univ.,
Tokyo Metro Univ., Riken]
5.34 mm(4.1’)
2.48 mm (1.9’)
(Photo by NASA/GSFC)
X-ray Photon
Principles of the XRS
Thermometer
X-ray Absorter
Heat Capacitance, C
Thermal Conductance, G
Implanted Traces
X-Ray Absorber
(HgTe)
Heat Sink, TS
Implanted Thermistor
Silicon Spacer
Silicon Pixel
Silicon Support Beams
The microcalorimeter in the XRS detects the temperature increase due to
absorption of a single X-ray photon. The small heat capacities and low temperature
lead to very small fluctuations, resulting in higher energy resolution compared to
ordinary semiconductor devices. The XRS can resolve very small energy
differences of X-ray photons.
The microcalorimeter must be
operated at about 60 mK.
A unique three-stage cryogenic
system consisting of solid neon,
liquid helium, and an adiabatic demagnetization refrigerator is
adopted to provide cooling for the
detector. The design of the neon
tank is optimized to work about 2
years in orbit, which determines
the lifetime of the whole cryogenic
system.
(photo by ISAS)
XRS Array Assembly
Number of pixels : 32
Absorber: HgTe (8 µm)
Pixel dimensions: 1.23  0.32 mm
(57”  15”)
Filling factor:
94.6 %
(Photo by NASA/GSFC)
XRS Flight Array Installed in CTS
Energy resolution of the XRS
DE = 8-9 eV below 3keV
DE = 11-14 eV at 8keV
0
5
Counts/bin
Mn K
10
15
Energy
(keV)
Monochromatic 6.391keV
Mn K
100
10
5.8
6.0
6.2
Energy (keV)
6.4
6.6
Expected performance of the XRS
Astro-E/XRS
Simulation of
Centaurus Cluster
100 ksec exposure
He-like FeK
Z = 0.01
(3000 km/sec)
CCD
Response
X-ray Imaging Spectrometer (XIS)
The XIS plays key role in simultaneous
imaging and spectroscopic
observations over the energy range of
0.5 - 12 keV. Many efforts have been
made to improve the performance of
ASCA’s X-ray CCDs and their related
electronics. Astro-E’s CCD is frontilluminated frame-transfer device with
1024x 1024 pixels. Each pixel is 24 µm
square and the size of the CCD is 25
mm x 25 mm. Energy resolution is
~120 eV at ~ 8 keV.
[Kyoto Univ., Osaka Univ., ISAS, MIT]
(photo by ISAS)
XIS CCD Assembly
(photo by MIT)
Hard X-ray Detector (HXD)
HXD is a collimated instrument
sensitive in the band of 10 keV to 600
keV. It is designed to minimize the
detector backgrounds by its improved
shielding. The HXD sensor is consisting
of 16 main detectors and the
surrounding 20 crystal scintillators for
active shielding. Each detector unit
consists of two types of detectors:
Gadolinium silicate (GSO) crystal
buried deep in the bottom of the Wellshape Bismuth germanate (BGO)
crystal, and PIN silicon diodes located
inside the well.
[Univ. of Tokyo, ISAS, RCNP]
(photo by ISAS)
The HXD is a phoswich counter with the “well-type”
structure. The BGO crystal actively shields the
detection part. It also acts as an active collimator,
which provides a fine field of view with a small
amount of passive material.
The silicon PIN diode on GSO.
covers lower energy band
below ~40 keV, while the GSO
is sensitive above ~30 keV.