AstroH XRT system

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Astro-H XRT system

• H.Awaki (Ehime University)
• Astro-H XRT team
• (Nagoya Univ., NASA/GSFC, ISAS/JAXA, Ehime Univ.,
  Chubu Univ., Osaka City Univ., Nara womens
  Univ., Kobe Univ., Chuo Univ., JASRI/SPring-8,
  JST )

Contents 1. Astro-H
satellite 2. XRT components design 3. HXT (foil
production, calibration facility) 4. SXT
(improvements from Suzaku to Astro-H)
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Astro-H
The new Japanese X-ray mission following
Suzaku Astro-H is currently planned to launch in
fiscal 2013.
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
Length 14 m Weight 2.5 t Launch vehicle JAXA
HII-A Orbit 550 km circular i 31
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Instruments
Soft X-ray telescope
Hard X-ray telescope (HXT)
Fixed Optical bench
FL12 m
radiator
FL5.6 m
Soft X-ray spectrometer
Soft X-ray imager
SUN
(Micro calorimeter)
(X-ray CCD camera)
Extended Optical bench
Soft Gamma-ray detector
Hard X-ray Imager (HXI)
Double-sided Si Strip (4 layer) detector CdTe
double strip(1 layer) detector
Si/CdTe Compton camera
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
  _at_ 40 keV
• High-resolution spectroscopy with E/?Egt1000
  300cm2 _at_ 6 keV
• Wide band observation from 0.3 to 600 keV.

Effective area
Energy resolution
SXTSXI
Astro-H
XMM-Newton
HXTHXI
Collecting area in the soft X-ray band
Effective area cm2 10
100 1000
Energy band
SXTSXS
SGD (Compton mode)
Chandra
Suzaku
Angular resolution
0.1 1 10 100
1000 Energy
keV
Collecting area in the hard X-ray band
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Hard X-ray region Continuum Sensitivity for
point source
Power law spectrum of a 1 mCrab source with G1.7
?E/E0.5 T100 ks
HXI simulation for absorbed AGNs
(Terashima)
10-4 10-5 10-6 10-7 10-8
1 mCrab, NH0 1 mCrab, NH1024 cm-2 0.1
mCrab, NH1024 cm-2 0.01 mCrab, NH1024 cm-2
T100ks
Suzaku-HXD (PIN)
Suzaku-HXD (GSO)
Flux (photons s-1 keV-1 cm-2)
ASTRO-H SGD
3 of NXB
ASTRO-H HXI
1 10
100
5 10 20 50 100 200 500
Energy ( keV)
Energy ( keV)
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 NH1024 cm-2,
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Main features of Astro-H

• Large collecting area above 10 keV
• High-resolution spectroscopy with E/?Egt1000
• Wide band observation from 0.3 to 600 keV.

Effective area
Energy resolution
SXTSXI
Astro-H
XMM-Newton
HXTHXI
Collecting area in the soft X-ray band
Effective area cm2 10
100 1000
Energy band
SXTSXS
SGD (Compton mode)
Chandra
Suzaku
Angular resolution
0.1 1 10 100
1000 Energy
keV
Collecting area in the hard X-ray band
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High resolution Spectroscopy in the soft X-ray
region
Mn Ka
Astro-H/SXS
FWHM 4 eV

• 5880 5900 5920
• Energy (eV)

Takahashi et al. 2008, SPIE
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10 Energy (keV)
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_at_40
  keV
• High-resolution spectroscopy with E/?Egt1000
  300cm2_at_6keV
• Wide band observation from 0.3 to 600 keV.

Effective area
SXTSXI
We can obtain these features with X-ray
telescope.
HXTHXI
Effective area cm2 10
100 1000
SXTSXS
SGD (Compton mode)
Telescope is crucial for Astro-H ? XRT system.
0.1 1 10 100
1000 Energy
keV
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2. XRT component
TS 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.
Without PC
With PC
Focal plane images formed by stray
light These panels show simulated images of a
point source locating at (-20, 0) in cases of
without and with pre-collimator .

(Serlemitsos et al. 2007)
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XRT design parameters
- S
PET
0.2 um Polyimide
t0.15, 0.23, 0.31 mm h100mmx2
210
1680
Weight 56 kg
80 kg Angular resolution 1
arcmin 1.7 arcmin
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Hard X-ray Telescope (HXT)
Depth-graded multilayer (ML) technology (supper
mirror)
30 keV
Supper mirror
dn lt d1
measurement model
Pt/C Multilayer
Critical angle of Pt at 30 keV (0.161 deg)
Epoxy 0.02mm
Al Substrate 0.2 mm
Reflectivity of Super mirror coating on float
glass. The periodic structure is 46-126 Å level
and micro-roughness3Å.
Reflector of HXT with depth-graded ML is produced
through a replication method The ML uses the
Bragg reflection and enhance reflectivity beyond
the critical energy by the X-ray interference.
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Sputtering Chambers
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Foil Production _at_ Nagoya Univ.
(1) Forming foil
(3) Spray epoxy
(2) ML coating
(4) Curing
(5) Separation
(6) Finished reflector
Quality check
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Surface profile of the reflector
Axial figure profile of a recently fabricated
test reflector
2mm
Replication mandrel (glass tube) Replicated
reflector
Reflectivity measurement
E30 keV s3A
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.
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Synchrotron radiation facility SPring-8
Super Photon ring 8GeV
Synchrotron radiation ranging from the soft X-ray
(E300eV) to hard X-ray (E300keV) region is
available with high intensity.

• We use this facility for
• Reflectivity measurement of an X-ray reflector
• Image quality measurement of an XRT

These data are valuable for making the response
function of HXT.
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Reflectivity measurement _at_ SPring-8 BL20B2
Experimental Hutch 2 3
beam size 0.5x0.5mm
E/DE104
60 keV
30 keV
measurement model
measurement model
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Image measurement _at_ SPring-8 BL20B2
Beam divergence lt 1, when beam size 0.3x0.3mm
Telescope holder
HXT
E/DE104
Stages
12 m
Direct beam after 4-axis slit
XRT for a balloon bone experiment
Telescope holder
SUMIT XRT 1.54 arcmin (HPD) (87pairs)
Stages
An X-ray image will be obtained by a pencil beam
scan.
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Soft X-ray telescope for SXSimprovements 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

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Reflector fixing (testing with the Suzaku spare)
60 pairs Test 1.26 arcmin
Suzaku (1.7arcmin HPD)
Encircled Energy Function 0 0.5
1
ASCA (3.7arcmin HPD)
0 2 4 6 8
10 Diameter (arcmin)
Okajima et al. 2009
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.
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Production schedule
Mass production of HXT foils
We will start mass-production of foils for HXT in
April 2010.
launch
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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/?Egt1000
• 
  (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 status
• We 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.