Download - Astro-H XRT system
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Astro-H XRT systemH.Awaki (Ehime University)
+ Astro-H XRT team
(Nagoya Univ., NASA/GSFC, ISAS/JAXA, Ehime Univ., Chubu Univ., Osaka City Univ., Nara women’s Univ., Kobe Univ., Chuo Univ., JASRI/SPring-8, JST )
Contents1. Astro-H satellite2. XRT components & design
3. HXT (foil production, calibration facility)
4. SXT (improvements from Suzaku to Astro-H)
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Astro-H
Scientific objectives(1) Evolution of clusters of galaxies(2) Growth of super-massive black holes(3) Behavior of material in extreme gravitational field(4) Particle acceleration in the universe(5) Dark matter and dark energy
Scientific objectives(1) Evolution of clusters of galaxies(2) Growth of super-massive black holes(3) Behavior of material in extreme gravitational field(4) Particle acceleration in the universe(5) Dark matter and dark energy
The new Japanese X-ray mission following SuzakuAstro-H is currently planned to launch in fiscal 2013.
Length: 14 mWeight: 2.5 tLaunch vehicle: JAXA HII-AOrbit : 550 km circular i = 31 °
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Instruments
FL=5.6 m
Double-sided Si Strip (4 layer) detector + CdTe double strip(1 layer) detector
(Micro calorimeter) (X-ray CCD camera)
Extended Optical bench
Fixed Optical bench
radiator
SUN
Si/CdTe Compton camera
Soft X-ray telescopeHard X-ray telescope (HXT)
FL=12 m
Soft X-ray imagerSoft X-ray spectrometer
Soft Gamma-ray detector
Hard X-ray Imager (HXI)
With these instruments, Astro-H will cover the bandpass between 0.3 keV to 600 keV.
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Main features of Astro-H• Large collecting area above 10 keV 200cm2 @ 40 keV
• High-resolution spectroscopy with E/ΔE>1000 300cm2 @ 6 keV
• Wide band observation from 0.3 to 600 keV.
Angular resolution
Collecting areain the hard X-ray band
Suzaku
XMM-Newton
Chandra
Astro-H
Energy resolution
Collecting areain the soft X-ray band
Energy band
Effective area
0.1 1 10 100 1000 Energy [keV]
E
ffec
tive
area
[cm
2]
10
10
0
1
000
HXT+HXI
SGD (Compton mode)
SXT+SXS
SXT+SXI
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Hard X-ray region: Continuum Sensitivity for point source
Energy ( keV)
5 10 20 50 100 200 500
Power law spectrum of a 1 mCrab source with Γ=1.7
F
lux
(ph
oto
ns
s-1 k
eV
-1 c
m-2) 10-4
10-5
10-6
10-7
10-8
ΔE/E=0.5T=100 ks
Thank to the hard X-ray imaging system of Astro-H, the sensitivity for point sources is much improved above 10 keV. ⇒ The detection limit of Astro-H is about two orders of magnitude fainter than that of Suzaku PIN.
We will be able to obtain a spectrum of 0.01 mCrab source with NH=1024 cm-2,
HXI simulation for absorbed AGNs (Terashima)
3% of NXB
T=100ks
1 10 100
Energy ( keV)
ASTRO-H HXIASTRO-H SGD
Suzaku-HXD (GSO)Suzaku-HXD (PIN)
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Main features of Astro-H• Large collecting area above 10 keV• High-resolution spectroscopy with E/ΔE>1000• Wide band observation from 0.3 to 600 keV.
Angular resolution
Collecting areain the hard X-ray band
Suzaku
XMM-Newton
Chandra
Astro-H
Energy resolution
Collecting areain the soft X-ray band
Energy band
Effective area
0.1 1 10 100 1000 Energy [keV]
E
ffec
tive
area
[cm
2]
10
10
0
1
000
HXT+HXI
SGD (Compton mode)
SXT+SXS
SXT+SXI
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High resolution Spectroscopy in the soft X-ray region
FWHM~4 eV
5860 5880 5900 5920 Energy (eV)
Mn Kα
Takahashi et al. 2008, SPIE
1 10 Energy (keV)
Astro-H/SXS
A large effective area with a high energy resolution is realized by the NASA/GSFC thin foil optics (SXT-S). The thin foil optics has benefits of light weight and high throughput.
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Main features of Astro-H• Large collecting area above 10 keV 200cm2@40 keV
• High-resolution spectroscopy with E/ΔE>1000 300cm2@6keV
• Wide band observation from 0.3 to 600 keV.
Effective area
0.1 1 10 100 1000 Energy [keV]
E
ffec
tive
area
[cm
2]
10
10
0
1
000
HXT+HXI
SGD (Compton mode)
SXT+SXS
SXT+SXI We can obtain these features with X-ray telescope.
Telescope is crucial for Astro-H
XRT system.
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2. XRT componentTS is placed over the entire aperture of each mirror in order to isolate the XRT from space thermally.
PC is set on the top on the mirror in order to reduce the stray light.
Mirrors employ tightly-nested, conically approximated thin-foil Wolter-I optics.
Focal plane images formed by stray lightThese panels show simulated images of a point source locating at (-20’, 0) in cases of without and with pre-collimator . (Serlemitsos et al. 2007)
Without PC With PC
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PET0.2 um Polyimide
XRT design parameters
~210
t0.15, 0.23, 0.31 mm h100mmx2
~1680
- S
Light weight and high throuput
Weight ~56 kg ~ 80 kgAngular resolution 1 arcmin 1.7 arcmin
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Hard X-ray Telescope (HXT)
Al Substrate 0.2 mm
Epoxy 0.02mm
Pt/C Multilayer
Supper mirror
Depth-graded multilayer (ML) technology (supper mirror)
Reflector of HXT with depth-graded ML is produced through a replication methodThe ML uses the Bragg reflection and enhance reflectivity beyond the critical energy by the X-ray interference.
30 keV
measurementmodel
Critical angle of Pt at 30 keV(0.161 deg)
Reflectivity of Super mirror coating on float glass. The periodic structure is 46-126 Å level and micro-roughness~3Å.
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Sputtering Chambers
Sputtering Chamber
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Foil Production @ Nagoya Univ.(1) Forming foil
(4) Curing(5)
Separation
(3) Spray epoxy
(2) ML coating
(6) Finished reflector
Quality check
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Surface profile of the reflectorAxial figure profile of a recently fabricated test reflector
2m
Replication mandrel (glass tube)Replicated reflector
Figure error of this test reflector is ±1 micron (P-V).
Based on a reflectivity measurement, surface roughness is about 3-4A, which is comparable to that of glass tube. smooth surface is trasferred to the foil.
E=30 keVσ~3A
Reflectivity measurement
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Synchrotron radiation facility SPring-8
We use this facility for • Reflectivity measurement of an
X-ray reflector• Image quality measurement of
an XRT
SPring-8 BL20B2
Super Photon ring 8GeV
Synchrotron radiation ranging from the soft X-ray (E=300eV) to hard X-ray (E=300keV) region is available with high intensity.
These data are valuable for making the response function of HXT.
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Reflectivity measurement @ SPring-8 BL20B2Experimental Hutch 2 & 3
E/E~104
beam size = 0.5x0.5mm
30 keV
measurementmodel
measurementmodel
60 keV
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Image measurement @ SPring-8 BL20B2
E/E~104
12 m
HXT
Stages
Beam divergence < 1”, when beam size = 0.3x0.3mm
Direct beam after 4-axis slit
An X-ray image will be obtained by a pencil beam scan.
XRT for a balloon bone experiment
Telescopeholder
Stages
Telescope holder
SUMIT XRT: 1.54 arcmin (HPD) (87pairs)
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Soft X-ray telescope for SXS~improvements from Suzaku to Astro-H ~
• (1) Substrate Shaping– To use thicker Al substrate for
the larger radii.– To use significantly larger
number of forming mandrels for better substrate shaping
• (2) Precise positioning– To make precise alignment bars– Reflector will be fixed onto the
bar by glue
• (3) Stronger housing– More mass is allocated to the
mirror housing
Suzaku Astro-H
Diameter 40 cm 45 cm
Focal length 4.5 / 4.75 m 5.6 m
Foil thickness 152 m 152, 229, 305 m
# of shells 168/175 ~210
Forming Mandrels
40 150
Precise Alignment bars
~40 m walk
~3 m accuracy
Reflector positioning
Free within a groove
Fix by glue
Strong housing(Housing mass)
25% of total mass
40% of total mass
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Reflector fixing (testing with the Suzaku spare)
Since groove width of alignment bar is wider than the reflector thickness by 25 µm and the reflectors are free to move. Test gluing using “the Suzaku spare hardware”
1.26 arcmin (HPD) with 60 pairs.⇒The reflector will be fixed onto the bar by glue for ASTRO-H in order to improve angular resolution.
0 2 4 6 8 10 Diameter (arcmin)
Enc
ircle
d E
nerg
y F
unct
ion
0
0.
5
1
60 pairs Test1.26 arcmin Suzaku (1.7arcmin HPD)
ASCA (3.7arcmin HPD)
Okajima et al. 2009
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Production schedule
We will start mass-production of foils for HXT in April 2010. launch
Mass production of HXT foils
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Summary• Astro-H mission The new Japanese X-ray mission is currently planed to launch in 2013. the unique features are (1) Large collecting area above 10 keV (2) High-resolution spectroscopy with E/ΔE>1000 (3) Wide band observation from 0.3 to 600 keV. .
• XRT system X-ray telescope system consists of two HXT (5-80 keV) and two SXT (0.3-10
keV). Mirrors employ tightly-nested, conically approximated thin-foil Wolter-I optics. HXTs employ Pt/C depth-graded multilayers, while SXTs employ a single layer of
gold.
• Current statusWe are performing test productions, and are tuning production facility.Based on basic studies, detailed studies of the flight design are in progress, and
production facilities for the Astro-H XRT system are close to finish.