We report our recent activities for a development of a new X-ray interferometer with a beam splitter and discuss a possible observation of some celestial objects. The X-ray interferometer consists of two flat mirrors and one flat beam splitter. Samples of the beam splitter and the mirrors have been designed and fabricated. We measured the reflectivity of the mirrors and the reflectivity and transmission of the beam splitters with a synchrotron source at KEK-PF. Obtained results of the mirrors are roughly consistent with the design values, but the reflectivity of the beam splitter is roughly half of the design value. Using these measured values, we estimated required area and observation-time to obtain fringe signals of celestial objects. We concluded that a broad-band interferometer using non-dispersive high spectral resolution detector, such as the micro-calorimeter array, is essential for the future development.
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.
We present the development status of the Soft X-ray Spectrometer (SXS) onboard the ASTRO-H mission. The SXS provides the capability of high energy-resolution X-ray spectroscopy of a FWHM energy resolution of < 7eV in the energy range of 0.3 – 10 keV. It utilizes an X-ray micorcalorimeter array operated at 50 mK. The SXS microcalorimeter subsystem is being developed in an EM-FM approach. The EM SXS cryostat was developed and fully tested and, although the design was generally confirmed, several anomalies and problems were found. Among them is the interference of the detector with the micro-vibrations from the mechanical coolers, which is the most difficult one to solve. We have pursued three different countermeasures and two of them seem to be effective. So far we have obtained energy resolutions satisfying the requirement with the FM cryostat.
KEYWORDS: X-rays, Signal processing, Sensors, Field programmable gate arrays, Digital signal processing, Clocks, Fermium, Frequency modulation, Spectroscopy, Photons
The soft X-ray spectrometer (SXS) aboard ASTRO-H is equipped with dedicated digital signal processing units called pulse shape processors (PSPs). The X-ray microcalorimeter system SXS has 36 sensor pixels, which are operated at 50 mK to measure heat input of X-ray photons and realize an energy resolution of 7 eV FWHM in the range 0.3–12.0 keV. Front-end signal processing electronics are used to filter and amplify the electrical pulse output from the sensor and for analog-to-digital conversion. The digitized pulses from the 36 pixels are multiplexed and are sent to the PSP over low-voltage differential signaling lines. Each of two identical PSP units consists of an FPGA board, which assists the hardware logic, and two CPU boards, which assist the onboard software. The FPGA board triggers at every pixel event and stores the triggering information as a pulse waveform in the installed memory. The CPU boards read the event data to evaluate pulse heights by an optimal filtering algorithm. The evaluated X-ray photon data (including the pixel ID, energy, and arrival time information) are transferred to the satellite data recorder along with event quality information. The PSP units have been developed and tested with the engineering model (EM) and the flight model. Utilizing the EM PSP, we successfully verified the entire hardware system and the basic software design of the PSPs, including their communication capability and signal processing performance. In this paper, we show the key metrics of the EM test, such as accuracy and synchronicity of sampling clocks, event grading capability, and resultant energy resolution.
KEYWORDS: X-rays, Digital signal processing, Spectroscopy, Signal processing, Space operations, Performance modeling, Field programmable gate arrays, Electronics, Analog electronics, Satellites
We present the development status of the Pulse Shape Processor (PSP), which is the on-board digital electronics
responsible for the signal processing of the X-ray microcalorimeter spectrometer instrument (the Soft X-ray
Spectrometer; SXS) for the ASTRO-H satellite planned to be launched in 2014. We finished the design and
fabrication for the engineering model, and are currently undertaking a series of performance verification and
environmental tests. In this report, we summarize the results obtained in a part of the tests completed in the
first half of this year.
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated
by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the highenergy
universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV.
These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3–12 keV with
high spectral resolution of ΔE ≦ 7 eV, enabled by a micro-calorimeter array located in the focal plane of
thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5–80 keV, located in the focal plane of
multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4–12 keV,
with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera
type soft gamma-ray detector, sensitive in the 40–600 keV band. The simultaneous broad bandpass, coupled
with high spectral resolution, will enable the pursuit of a wide variety of important science themes.
We report our examination of a new X-ray interferometer for observation of celestial objects and our recent work
for preparation of laboratory experiments. The new X-ray interferometer is consisting of two
at mirrors and
one
at beam splitter which are used as grazing incident optics. The aimed wave length is a O-K band or a C-K
band. The beam splitter and the mirrors are fabricated by Mo/Si multilayer. We measured their
atness and
found that the measured
atness is acceptable for the test experiment. A pin hole X-ray source is also preparing
for a laboratory experiment in order to demonstrate a X-ray interference. We investigated a possible observation
of accretion disks around BHs and nearby stars. With a reasonable size of the base line, we can measure their
size and possibly we can obtain an evidence of a black hole shadow.
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