The Resolve instrument onboard the X-ray Astronomy Recovery Mission (XARM) consists of
an array of 6x6 silicon-thermistor microcalorimeters cooled down to 50 mK
and a high-throughput X-ray mirror assembly with a focal length of 5.6 m.
The XARM is a recovery mission of ASTRO-H/Hitomi,
and is developed by international collaboration of Japan, USA, and Europe.
The Soft X-ray Spectrometer (SXS) onboard Hitomi demonstrated high resolution
X-ray spectroscopy of ~ 5 eV FWHM in orbit for most of the microcalorimeter pixels.
The Resolve instrument is planned to mostly be a copy of the Hitomi SXS and
Soft X-ray Telescope designs, though several changes are planned
based on the lessons learned of Hitomi.
The energy resolution budget of the microcalorimeters is updated,
reflecting the Hitomi SXS results.
We report the current status of the Resolve instrument.
The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
The Soft X-ray Imager (SXI) is an imaging spectrometer using charge-coupled devices (CCDs) aboard the Hitomi x-ray observatory. The SXI sensor has four CCDs with an imaging area size of 31 mm×31 mm arranged in a 2×2 array. Combined with the x-ray mirror, the Soft X-ray Telescope, the SXI detects x-rays between 0.4 and 12 keV and covers a 38′×38′ field of view. The CCDs are P-channel fully depleted, back-illumination type with a depletion layer thickness of 200 μm. Low operation temperature down to −120°C as well as charge injection is employed to reduce the charge transfer inefficiency (CTI) of the CCDs. The functionality and performance of the SXI are verified in on-ground tests. The energy resolution measured is 161 to 170 eV in full width at half maximum for 5.9-keV x-rays. In the tests, we found that the CTI of some regions is significantly higher. A method is developed to properly treat the position-dependent CTI. Another problem we found is pinholes in the Al coating on the incident surface of the CCDs for optical light blocking. The Al thickness of the contamination blocking filter is increased to sufficiently block optical light.
The Hitomi (ASTRO-H) mission is the sixth Japanese X-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. After a successful launch on 2016 February 17, the spacecraft lost its function on 2016 March 26, but the commissioning phase for about a month provided valuable information on the on-board instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.
We report here the performance of the SXI on ASTRO-H that was started its operation from March,02 2016. The SXI consists of 4 CCDs that cover 38' X 38' sky region. They are P-channel back-illumination type CCD with a depletion layer of 200 μm. Charge injection (CI) method is applied from its beginning of the mission. Two single stage sterling coolers are equipped with the SXI while one of them has enough power to cool the CCD to -110°C. There are two issues in the SXI performance: one is a light-leak and the other is a cosmic-ray echo. The light-leak is due to the fact that the day-Earth irradiates visible lights onto the SXI body through holes in the satellite base plate. It can be avoided by selecting targets not on the anti-day-Earth direction. The cosmic-ray echo is due to the improper parameter values that is fixed by revising them with which the cosmic-ray echo does not affect the image. Using the results of RXJ1856.5-3754, we confirm that the possible contaminants on the CCD is well within our expectation.
The Soft X-ray Imager (SXI) is an X-ray CCD camera onboard the ASTRO-H X-ray observatory. The CCD chip used is a P-channel back-illuminated type, and has a 200-µm thick depletion layer, with which the SXI covers the energy range between 0.4 keV and 12 keV. Its imaging area has a size of 31 mm x 31 mm. We arrange four of the CCD chips in a 2 by 2 grid so that we can cover a large field-of-view of 38’ x 38’. We cool the CCDs to -120 °C with a single-stage Stirling cooler. As was done for the CCD camera of the Suzaku satellite, XIS, artificial charges are injected to selected rows in order to recover charge transfer inefficiency due to radiation damage caused by in-orbit cosmic rays. We completed fabrication of flight models of the SXI and installed them into the satellite. We verified the performance of the SXI in a series of satellite tests. On-ground calibrations were also carried out and detailed studies are ongoing.
Soft X-ray Imager (SXI) is a CCD camera onboard the ASTRO-H satellite which is scheduled to be launched in 2015. The SXI camera contains four CCD chips, each with an imaging area of 31mm x 31 mm, arrayed in mosaic, covering the whole FOV area of 38′ x 38′. The CCDs are a P-channel back-illuminated (BI) type with a depletion layer thickness of 200 _m. High QE of 77% at 10 keV expected for this device is an advantage to cover an overlapping energy band with the Hard X-ray Imager (HXI) onboard ASTRO-H. Most of the flight components of the SXI system are completed until the end of 2013 and assembled, and an end-to-end test is performed. Basic performance is verified to meet the requirements. Similar performance is confirmed in the first integration test of the satellite performed in March to June 2014, in which the energy resolution at 5.9 keV of 160 eV is obtained. In parallel to these activities, calibrations using engineering model CCDs are performed, including QE, transmission of a filter, linearity, and response profiles.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions developed by the Institute of Space and Astronautical Science (ISAS), with a planned launch in 2015. The ASTRO-H mission is equipped with a suite of sensitive instruments with the highest energy resolution ever achieved at E > 3 keV and a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. The simultaneous broad band pass, coupled with the high spectral resolution of ΔE ≤ 7 eV of the micro-calorimeter, will enable a wide variety of important science themes to be pursued. ASTRO-H is expected to provide breakthrough results in scientific areas as diverse as the large-scale structure of the Universe and its evolution, the behavior of matter in the gravitational strong field regime, the physical conditions in sites of cosmic-ray acceleration, and the distribution of dark matter in galaxy clusters at different redshifts.
Soft X-ray Imager (SXI) is a CCD camera onboard the ASTRO-H satellite which is scheduled to be launched
in 2014. The SXI camera contains four CCD chips, each with an imaging area of 31mm×
31 mm, arrayed in
mosaic, which cover the whole FOV area of 38' ×
38'. The SXI CCDs are a P-channel back-illuminated (BI) type
with a depletion layer thickness of 200 μm. High QE of 77% at 10 keV expected for this device is an advantage
to cover an overlapping energy band with the Hard X-ray Imager (HXI) onboard ASTRO-H. Verification with
engineering model of the SXI has been performed since 2011. Flight model design was fixed and its fabrication
has started in 2012.
We present the development of the data acquisition system for the X-ray CCD camera (SXI: Soft X-ray Imager)
onboard the ASTRO-H satellite. Two types of breadboard models (BBMs) of SXI electronics have been produced
to verify the functions of each circuit board and to establish the data acquisition system from CCD to SpaceWire
(SpW) I/F. Using BBM0, we verified the basic design of the CCD driver, function of the Δ∑-ADC, data
acquisition of the frame image, and stability of the SpW communication. We could demonstrate the energy
resolution of 164 eV (FWHM) at 5.9 keV. Using BBM1, we verified acquisition of the housekeeping information
and the frame images.
We report on the development of the X-ray CCD for the soft X-ray imager (SXI) onboard ASTRO-H. SXI CCDs are
P-channel, back-illuminated type manufactured by Hamamatsu Photonics K. K.
Experiments with prototype CCD for the SXI shows the device has a depletion layer as thick as 200μm, high efficiency for hard X-rays.
By irradiating soft X-rays to the prototype CCD for the SXI.
At the same time, we found a significant low energy tail in the soft X-ray response of the SXI prototype CCD.
We thus made several small size CCD chips with different treatment in processing the surface layers.
CCDs with one of the surface layers treatment show a low energy tail of
which intensity is one order of magnitude smaller than that of the original SXI prototype CCD for 0.5keV X-ray incidence.
The same treatment will be applied to the flight model CCDs of the SXI.
We also performed experiments to inject charge with the SXI prototype CCD, which is needed to mitigate the radiation damage in the orbit.
We investigated the operation conditions of the charge injection.
Using the potential equilibration method, charges are injected in each column homogeneously,
though the amount of the charge must be larger than 20ke<sup>-</sup>.
Soft X-ray Imager (SXI) is a CCD camera onboard the ASTRO-H satellite which is scheduled to be launched
in 2014. The SXI camera contains four CCD chips, each with an imaing aread of 31mmx31 mm, arrayed in
mosaic, which cover the whole FOV area of 38'x38'. The SXI CCD of which model name is HPK Pch-NeXT4
is a P-channel type, back-illuminated, fully depleted device with a thickness of 200μm. We have developed an
engineering model of the SXI camera body with coolers, and analog electronics for them. Combined with the
bread board digital electronics, we succeeded in operation the whole the SXI system. The CCDs are cooled down
to -120°C with this system, and X-rays from <sup>55</sup>Fe sources are detected. Although optimization of the system is in
progress, the energy resolution of typical 200 eV and best 156 eV (FWHM) at 5.9 keV are obtained. The readout
noise is 10 e<sup>-</sup> to 15 e<sup>-</sup>, and to be improved its goal value of 5 e<sup>-</sup>. On-going function tests and environment tests
reveal some issues to be solved until the producntion of the SXI flight model in 2012.
We have developed a new back-illuminated (BI) CCD which has an Optical Blocking Layer (OBL) directly coating
its X-ray illumination surface with Aluminum-Polyimide-Aluminum instead of Optical Blocking Filter (OBF).
OBL is composed of a thin polyimide layer sandwiched by two Al layers. Polyimide and Al has a capability to
cut EUV and optical light, respectively. The X-ray CCD is affected by large doses of extreme ultraviolet (EUV)
radiation from Earth sun-lit atmosphere (airglow) in orbit as well as the optical light.
In order to evaluate the performance of the EUV-attenuating polyimide of the OBL, we measured the EUV
transmission of both the OBL and the OBF at energies between 15-72 eV by utilizing a beam line located
at the Photon Factory in High Energy Accelerator Research Organization (KEK-PF). We obtained the EUV
transmission to be 3% at 41 eV which is the same as the expected transmission from the designed thickness of
the polyimide layer. We also found no significant change of the EUV transmission of polyimide over the nine
month interval spanned by out two experiments.
We also measured the optical transmission of the OBL at wavelengths between 500-900Å to evaluate the
performance of the Al that attenuates optical light, and found the optical transmission to be less than 4×10<sup>-5</sup>.