HiZ-GUNDAM is a future satellite mission for gamma-ray burst observations. One of the mission instruments is the wide-field X-ray monitor with a field of view (FoV) of 0.5 steradian at 0.4 to 4.0 keV, consisting of Lobster Eye Optics (LEO) and focal-imaging pixel sensors. LEOs need to be spatially well-aligned to achieve both a wide FoV and fine accuracy in determining the location of X-ray transients. An alignment method is being investigated with visible light and shape measurements. We developed a titanium frame for positioning two LEO segments and estimated visible light on LEOs. We will report development of the alignment method.
HiZ-GUNDAM is a candidate of future satellite mission for the Japanese competitive M-class mission by ISAS/JAXA to progress a time-domain astronomy and multi-messenger astronomy with gamma-ray burst (GRB) phenomena. The science goals are (1) to probe the early universe with high redshift GRBs at z > 7, and (2) to promote the gravitational wave astronomy with short GRB. HiZ-GUNDAM has been successfully passed a review for pre-project candidate in November 2021, and its team is working on the concept study. We will introduce the sciences and mission overview of HiZ-GUNDAM.
The HiZ-GUNDAM (high-z Gamma-ray bursts for UNraveling the Dark Ages Mission) is a time-domain and multi-messenger astronomy mission by monitoring high-energy astronomical transient events such as gamma-ray bursts (GRBs). The HiZ-GUNDAM is designed to provide alerts of high-redshift GRBs with an ultra-wide field X-ray monitor and a co-onboard 30-cm telescope for immediate photometric follow-up observations in the visible and near-infrared. The HiZ-GUNDAM satellite automatically changes its attitude toward the discovered transient object, starts the follow-up observations with the telescope, and sends alert information including the detailed position, the apparent magnitude and photometric redshift of the transient object within one hour. This mission was selected as one of the mission concept candidates of the competitively-chosen medium-class mission of ISAS/JAXA in the mid-2020s. The basic design of the breadboard model of the telescope is undergoing, and the verification plan of it is studied. The optics are cooled down to 200 K by radiation cooling, and infrared detectors are additionally cooled down to 120 K by a mechanical cooler. All mirrors in the telescope are made of the same aluminum-alloy to reduce the alignment errors during cooling. The four-band simultaneous observation is realized by three beam splitters. The HgCdTe and HyViSi detectors are installed in this telescope. Basic technologies for these specifications are demonstrated by our other missions. In addition, the onboard detection algorithm of high-redshift GRBs by distinguishing them from nearby dusty galaxies in the orbit is also studied. In this paper, we introduce the current status of the development of the telescope onboard HiZ-GUNDAM.
HiZ-GUNDAM is a future satellite mission which will lead the time-domain astronomy and the multi-messenger astronomy through observations of high-energy transient phenomena. A mission concept of HiZ-GUNDAM was approved by ISAS/JAXA, and it is one of the future satellite candidates of JAXA’s medium-class mission. We are in pre-phase A (before pre-project) and elaborating the mission concept, mission/system requirements for the launch in the late 2020s. The main themes of HiZ-GUNDAM mission are (1) exploration of the early universe with high-redshift gamma-ray bursts, and (2) contribution to the multi-messenger astronomy. HiZ-GUNDAM has two kinds of mission payload. The wide field X-ray monitors consist of Lobster Eye optics array and focal imaging sensor, and monitor ~1 steradian field of view in 0.5 – 4 keV energy range. The near infrared telescope has an aperture size 30 cm in diameter, and simultaneously observes four wavelength bands between 0.5 – 2.5 μm. In this paper, we introduce the mission overview of HiZ-GUNDAM.
We propose an optimized source detection algorithm with an X-ray wide-field imaging detector based on lobstereye (LE) optics to realize better sensitivity. In our method, we take two parts of region of interest (ROI) in which we test the number of X-ray events exceed a certain threshold level. Since we compose the condition that the excesses of the photons are required for the both parts of the ROI, we can lower the detection threshold level with a less false alert rate. We take two comparative methods in which the ROI consists of one part, and compared the performance of them. We formulated an appropriate threshold level and sensitivity for two comparable detection methods as well as our proposed method. We found that the detection sensitivity of our method is improved by a factor of about 30% at most than that of the comparable methods in the nominal case of the proposed HiZ-GUNDAM mission. We also found that which detection method has better sensitivity depends on the background event rate. We checked that the formulation works well by comparing to a Monte Carlo simulation in the case of the HiZ-GUNDAM condition. The formula can be applied to any future missions with LE optics to design which detection algorithm is suitable for optimizing sensitivity.
In this paper we report on development of an FPGA-based fast readout system of a CMOS image sensor for the future satellite mission HiZ-GUNDAM observing gamma-ray bursts (GRBs) in the 0.4–4 keV band. Since the typical durations of GRBs are about 0.1–100 s, an X-ray photon-counting capability with a time resolution of < 0.1 s is required. The FPGA-based signal processing system has the following functions: (1) take images with a few million pixels at a frame rate of >10 frames per second, (2) extract X-ray events by image subtraction, (3) compile position and energy information of the obtained X-ray events, and (4) transfer the information to an external CPU. A more detailed system configuration is reported.
Lobster eye optics (LEO) is an optics composed of many pores aligned along a sphere. Since the LEO can cover a wide field of view with good sensitivity in soft X-rays, it makes an ideal telescope to search for interesting transient sources such as high redshift gamma-ray bursts, electromagnetic counterparts of gravitational wave sources, and so on. We obtained two LEOs of different specifications manufactured by Photonis inc. (hereafter PLEO) and NNVT inc. (hereafter NLEO) and evaluated their X-ray performance. We confirmed that both LEOs focus parallel X-rays and make an image containing a center spot, cross arms, and scattering components at the focal plane, as suggested by Angel (1979). The full widths at half maximum of the measured point spread functions are ∼ 11′ (PLEO) and ∼ 4 ′ (NLEO). The effective areas of the central component at 1.5 keV are 1.37 cm2 (PLEO) and 2.58 cm2 (NLEO). Based on our developed simulator calibrated using our X-ray measurements, the position accuracy of the PLEO is expected to be less than 1′ if the number of detected photons is more than 500.
We are developing a micro satellite, Kanazawa-SAT3 , to be launched in FY2019. The main purpose of the mission is to localize X-ray transients coincide with gravitational wave events, e.g. short gamma-ray bursts, and to investigate the formation of extreme space-time of black holes and the origin of relativistic jet. We are developing a wide field X-ray imaging detector as a mission instrument. It has a couple of 1-dimensional imaging systems with a random coded aperture mask and silicon strip detectors. In this paper, we introduce the mission overview and the current status of Kanazawa-SAT3 and the flight model performance.
Hitomi (ASTRO-H) was the sixth Japanese x-ray satellite that carried instruments with exquisite energy resolution of <7 eV and broad energy coverage of 0.3 to 600 keV. The Soft Gamma-ray Detector (SGD) was the Hitomi instrument that observed the highest energy band (60 to 600 keV). The SGD design achieves a low background level by combining active shields and Compton cameras where Compton kinematics is utilized to reject backgrounds coming from outside of the field of view. A compact and highly efficient Compton camera is realized using a combination of silicon and cadmium telluride semiconductor sensors with a good energy resolution. Compton kinematics also carries information for gamma-ray polarization, making the SGD an excellent polarimeter. Following several years of development, the satellite was successfully launched on February 17, 2016. After proper functionality of the SGD components were verified, the nominal observation mode was initiated on March 24, 2016. The SGD observed the Crab Nebula for approximately two hours before the spacecraft ceased to function on March 26, 2016. We present concepts of the SGD design followed by detailed description of the instrument and its performance measured on ground and in orbit.
We are planning to launch a micro satellite, Kanazawa-SAT3 , at the end of FY2018 to localize X-ray transients associated with gravitational wave sources. Now we are testing a prototype model of wide-field Xray imaging detector named T-LEX (Transient Localization EXperiment). T-LEX is an orthogonally distributed two sets of 1-dimensional silicon strip detectors with coded aperture masks, and covers more than 1 steradian field of view in the energy range of 1 – 20 keV. Each dimension has 512 readout electrodes (totally 1,024 channels), and they are read out with application specific integrated circuits (ASICs) controlled by two onboard FPGAs. Moreover, each FPGA calculates the cross correlation between the X-ray intensity and mask patterns every 64 msec, makes a histogram of lightcurves and energy spectra, and also plays a role of telemetry/command interface to mission CPU. In this paper, we report an overview of digital electronics system. Especially, we focus on the high-speed imaging processor on FPGA and demonstrate its performance as an X-ray imaging system.
Hard X-ray imaging polarimeters are developed for the X-ray γ-ray polaeimtery satellite PolariS. The imaging polarimter is scattering type, in which anisotropy in the direction of Compton scattering is employed to measure the hard X-ray (10-80 keV) polarization, and is installed on the focal planes of hard X-ray telescopes. We have updated the design of the model so as to cover larger solid angles of scattering direction. We also examine the event selection algorithm to optimize the detection efficiency of recoiled electrons in plastic scintillators. We succeed in improving the efficiency by factor of about 3-4 from the previous algorithm and criteria for 18-30 keV incidence. For 23 keV X-ray incidence, the recoiled electron energy is about 1 keV. We measured the efficiency to detect recoiled electrons in this case, and found about half of the theoretical limit. The improvement in this efficiency directly leads to that in the detection efficiency. In other words, however, there is still a room for improvement. We examine various process in the detector, and estimate the major loss is primarily that of scintillation light in a plastic scintillator pillar with a very small cross section (2.68mm squared) and a long length (40mm). Nevertheless, the current model provides the MDP of 6% for 10mCrab sources, which are the targets of PolariS.
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.
The Soft Gamma-ray Detector (SGD) is one of science instruments onboard ASTRO-H (Hitomi) and features a wide energy band of 60{600 keV with low backgrounds. SGD is an instrument with a novel concept of "Narrow field-of-view" Compton camera where Compton kinematics is utilized to reject backgrounds which are inconsistent with the field-of-view defined by the active shield. After several years of developments, the flight hardware was fabricated and subjected to subsystem tests and satellite system tests. After a successful ASTRO-H (Hitomi) launch on February 17, 2016 and a critical phase operation of satellite and SGD in-orbit commissioning, the SGD operation was moved to the nominal observation mode on March 24, 2016. The Compton cameras and BGO-APD shields of SGD worked properly as designed. On March 25, 2016, the Crab nebula observation was performed, and, the observation data was successfully obtained.
We are planning a future gamma-ray burst (GRB) mission HiZ-GUNDAM to probe the early universe beyond the redshift of z > 7. Now we are developing a small prototype model of wide-field low-energy X-ray imaging detectors to observe high-z GRBs, which cover the energy range of 1 – 20 keV. In this paper, we report overview of its prototype system and performance, especially focusing on the characteristics and radiation tolerance of high gain analog ASIC specifically designed to read out small charge signals.
PolariS (Polarimetry Satellite) is a Japanese small satellite mission dedicated to polarimetry of X-ray and γ-ray sources. The primary aim of the mission is to perform hard X-ray (10-80 keV) polarimetry of sources brighter than 10 mCrab. For this purpose, PolariS employs three hard X-ray telescopes and scattering type imaging polarimeters. PolariS will measure the X-ray polarization for tens of sources including extragalactic ones mostly for the first time. The second purpose of the mission is γ-ray polarimetry of transient sources, such as γ-ray bursts (GRBs). Wide field polarimeters based on similar concept as that used in the IKAROS/GAP but with higher sensitivity will be used, and polarization measurement of 10 GRBs per year is expected.
KEYWORDS: Signal processing, Sensors, Avalanche photodetectors, Logic, Cameras, Analog electronics, Signal detection, Digital filtering, Field programmable gate arrays, Gamma radiation
The hard X-ray imager (HXI) and soft gamma-ray detector (SGD) onboard Astro-H observe astronomical objects with high sensitivity in the hard X-ray (5−80 keV) and soft gamma-ray (40−600 keV) energy bands. To achieve this high sensitivity, background rejection is essential, and these detectors are surrounded by large and thick bismuth germinate scintillators as an active shield. We have developed adequate trigger logic for both the HXI and SGD to process signals from main detector and BGO shield simultaneously and then we optimized the trigger delay and width, with consideration of the trigger latch efficiency. The shield detector system performs well, even after it is assembled as the HXI sensor. The energy threshold maintains the same level as that observed during the prototype development phase, and the experimental room background level of the main detector is successfully reduced by our optimized trigger timing.
We are now investigating and studying a small satellite mission HiZ-GUNDAM for future observation of gamma-ray bursts (GRBs). The mission concept is to probe “the end of dark ages and the dawn of formation of astronomical objects”, i.e. the physical condition of early universe beyond the redshift z > 7. We will consider two kinds of mission payloads, (1) wide field X-ray imaging detectors for GRB discovery, and (2) a near infrared telescope with 30 cm in diameter to select the high-z GRB candidates effectively. In this paper, we explain some requirements to promote the GRB cosmology based on the past observations, and also introduce the mission concept of HiZ-GUNDAM and basic development of X-ray imaging detectors.
The Soft Gamma-ray Detector (SGD) is one of observational instruments onboard the ASTRO-H, and will provide 10 times better sensitivity in 60{600 keV than the past and current observatories. The SGD utilizes similar technologies to the Hard X-ray Imager (HXI) onboard the ASTRO-H. The SGD achieves low background by constraining gamma-ray events within a narrow field-of-view by Compton kinematics, in addition to the BGO active shield. In this paper, we will present the results of various tests using engineering models and also report the flight model production and evaluations.
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.
PolariS (Polarimetry Satellite) is a Japanese small satellite mission dedicated to polarimetry of X-ray and γ-ray sources. The primary aim of the mission is to perform wide band X-ray (4-80 keV) polarimetry of sources brighter than 10 mCrab. For this purpose, Polaris employs three hard X-ray telescopes and two types of focal plane imaging polarimeters. PolariS observations will measure the X-ray polarization for tens of sources including extragalactic ones mostly for the first time. The second purpose of the mission is γ-ray polarimetry of transient sources, such as γ-ray bursts. Wide field polarimeters based on similar concept as that used in the IKAROS/GAP but with higher sensitivity, i.e., polarization measurement of 10 bursts per year, will be employed.
WISH, Wide-field Imaging Surveyor for High-redshiftt, is a space mission concept to conduct very deep and widefield
surveys at near infrared wavelength at 1-5μm to study the properties of galaxies at very high redshift beyond the
epoch of cosmic reionization. The concept has been developed and studied since 2008 to be proposed for future
JAXA/ISAS mission. WISH has a 1.5m-diameter primary mirror and a wide-field imager covering 850 arcmin2. The
pixel scale is 0.155 arcsec for 18μm pitch, which properly samples the diffraction-limited image at 1.5μm. The main
program is Ultra Deep Survey (UDS) covering 100 deg2 down to 28AB mag at least in five broad bands. We expect to
detect <104 galaxies at z=8-9, 103-104 galaxies at z=11-12, and 50-100 galaxies at z<14, many of which can be feasible
targets for deep spectroscopy with Extremely Large Telescopes. With recurrent deep observations, detection and light
curve monitoring for type-Ia SNe in rest-frame infrared wavelength is also conducted, which is another main science
goal of the mission. During the in-orbit 5 years observations, we expect to detect and monitor <2000 type-Ia SNe up to
z~2. WISH also conducts Ultra Wide Survey, covering 1000deg2 down to 24-25AB mag as well as Extreme Survey,
covering a limited number of fields of view down to 29-30AB mag. We here report the progress of the WISH project
including the basic telescope and satellite design as well as the results of the test for a proto-model of the flip-type filter
exchanger which works robustly near 100K.
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.
ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will feature wide energy band (60–600 keV) at a background level 10 times better than the current instruments on orbit. The SGD is complimentary to ASTRO-H’s Hard X-ray Imager covering the energy range of 5–80 keV. The SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive to the gamma-ray polarization, opening up a new window to study properties of gamma-ray emission processes. In this paper, we will present the detailed design of the SGD and the results of the final prototype developments and evaluations. Moreover, we will also present expected performance based on the measurements with prototypes.
KEYWORDS: Galactic astronomy, Space telescopes, Telescopes, Mirrors, Near infrared, Optical filters, Staring arrays, Ultraviolet radiation, James Webb Space Telescope, Sensors
WISH is a new space science mission concept whose primary goal is to study the first galaxies in the early universe.
We will launch a 1.5m telescope equipped with 1000 arcmin2 wide-field NIR camera by late 2010's in order to conduct
unique ultra-deep and wide-area sky surveys at 1-5 micron. The primary science goal of WISH mission is pushing the
high-redshift frontier beyond the epoch of reionization by utilizing its unique imaging capability and the dedicated
survey strategy. We expect to detect ~104 galaxies at z=8-9, ~3-6x103 galaxies at z=11-12, and ~50-100 galaxies at
z=14-17 within about 5 years of the planned mission life time. It is worth mentioning that a large fraction of these
objects may be bright enough for the spectroscopic observations with the extremely large telescopes. By adopting the optimized strategy for the recurrent observations to reach the depth, we also use the surveys to detect transient objects.
Type Ia Supernova cosmology is thus another important primary goal of WISH. A unique optical layout has been
developed to achieve the diffraction-limited imaging at 1-5micron over the required large area. Cooling the mirror and
telescope to ~100K is needed to achieve the zodiacal light limited imaging and WISH will achieve the required
temperature by passive cooling in the stable thermal environment at the orbit near Sun-Earth L2. We are conducting the
conceptual studies and development for the important components of WISH including the exchange mechanism for the
wide-field filters as well as the primary mirror fixation.
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
high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular
resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination
of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray
mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV)
provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD
camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray
detector (40-600 keV) . The micro-calorimeter system is developed by an international collaboration led
by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of
ΔE ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be
pursued.
ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage
and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will
feature wide energy band (40-600 keV) at a background level 10 times better than the current instruments on
orbit. SGD is complimentary to ASTRO-H's Hard X-ray Imager covering the energy range of 5-80 keV. The
SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield
where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as
a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good
energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due
to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive
to the gamma-ray polarization, opening up a new window to study properties of gamma-ray emission processes.
The ASTRO-H mission is approved by ISAS/JAXA to proceed to a detailed design phase with an expected
launch in 2014. In this paper, we present science drivers and concept of the SGD instrument followed by detailed
description of the instrument and expected performance.
The design for robotic telescopes to observe Gamma-Ray Burst (GRB) afterglows and the results of observations
are presented. Quickly fading bright GRB flashes and afterglows provide a good tool to study an extremely early
universe. However, most large ground-based telescopes cannot afford to follow-up the afterglows and flashes
quickly within a few hours since a GRB explosion. We re-modeled the existing middle-class 1.3 m &slasho; telescope of
the near infrared band at ISAS in Japan to match for the above requirement. We also set a small telescope of
30 cm diameter with a conventional CCD. These telescopes can monitor afterglows quickly within a few minutes
in J, H, Ks and R band with a grism spectrometer.
The hard X-ray imager (HXI) is the primary detector of the NeXT mission, proposed to explore high-energy
non-thermal phenomena in the universe. Combined with a novel hard X-ray mirror optics, the HXI is designed to
provide better than arc-minutes imaging capability with 1 keV level spectroscopy, and more than 30 times higher
sensitivity compared with any existing hard X-ray instruments. The base-line design of the HXI is improving to
secure high sensitivity. The key is to reduce the detector background as far as possible. Based on the experience
of the Suzaku satellite launched in July 2005, the current design has a well-type tight active shield and multi
layered, multi material imaging detector made of Si and CdTe. Technology has been under development for a
few years so that we have reached the level where a basic detector performance is satisfied. Design tuning to
further improve the sensitivity and reliability is on-going.
The hard X-ray detector (HXD) onboard Suzaku covers an energy range of 8-700 keV, and thus in combination with the CCD camera (XIS) gives us an opportunity of wide-band X-ray observations of celestial sources with a good sensitivity over the 0.3-700 keV range. All of 64 Si-PIN photo diodes, 16 GSO/BGO phoswich scintillators, and 20 anti-coincidence BGO scintillators in the HXD are working well since the Suzaku launch on July 2005. The rejection of background events is confirmed to be as effective as expected, and accordingly the HXD achieved the lowest background level of the previously or currently operational missions sensitive in the comparable energy range. The energy and angular responses and timing have been continuously calibrated by the data from the Crab nebula, X-ray pulsars, and other sources, and at present several % accuracy is obtained. Even though the HXD does not perform simultaneous background observations, it detected weak sources with a flux as low as ~0.5 mCrab; stars, X-ray binaries, supernova remnants, active galactic nuclei, and galaxy clusters. Extensive studies of background subtraction enables us to study weaker sources.
The solar powered sail spacecraft using a huge sail is a next Japanese engineering verification satellite planned to launch in 2012. It has a hybrid propulsion system with ion engines and a huge solar sail panel of 50 m in diameter. Based on the present mission plan, it will take about 6 years to cruise to Jupiter via Earth swing-bys and 5 more years to reach the Jovian L4 Trojan asteroids. During its cruising phase, we plan to mount a gamma-ray burst (GRB) detector with polarization detection capability which also works as one of the interplanetary network (IPN) to determine the GRB positions. The emission mechanism of GRB is thought to be the synchrotron radiation from the relativistic outflows. If the emission mechanism of GRBs is really synchrotron radiation, the emitted gamma-rays should be strongly polarized. The detection principle is the anisotropy of the Compton scattering. The Compton-scattered gamma-ray photons show the strongly biased distribution toward the vertical direction against the oscillating electric field vector. The design concept of our detector is simple but carefully
avoid a fake modulation. The plastic scintillator in one Compton-length as the scattering body is placed at the center, and 12 CsI scintillators are allocated around it. To avoid a fake modulation through the satellite body scattering, these detectors work in coincidence mode. The coincidence also helps to reduce the particle background. We will use the VA-TA ASIC and FPGA as the analog readout and the digital event processing, respectively, to make the detector weight of almost 2.0 kg. In this paper, we introduce the solar sail mission and show the overview of gamma-ray polarimeter.
The NeXT mission has been proposed to study high-energy non-thermal phenomena in the universe. The high-energy response of the super mirror will enable us to perform the first sensitive imaging observations up to 80 keV. The focal plane detector, which combines a fully depleted X-ray CCD and a pixelated CdTe detector, will provide spectra and images in the wide energy range from 0.5 keV to 80 keV. In the soft gamma-ray band upto ~1 MeV, a narrow field-of-view Compton gamma-ray telescope utilizing several tens of layers of thin Si or CdTe detector will provide precise spectra with much higher sensitivity than present instruments. The continuum sensitivity will reach several x 10-8 photons/s/keV/cm2 in the hard X-ray region and a few x 10-7 photons/s/keV/cm2 in the soft gamma-ray region.
The Hard X-ray Detector (HXD-II), one of instruments onboard the Astro-E2 satellite to be launched in February 2005, is in the final stage of its development. The HXD-II probes the universe in the energy range of 10-600 keV with a sensitivity by an order of magnitude better than those of previous missions. The assembly of the HXD-II completed in January 2004, followed by a series of pre-launch qualification tests. As a result, the design goals of the HXD-II have been met. These include; a background level of 5 x 10-6 counts/s/keV/cm2 at 200 keV for GSO and 1 x 10-5 counts/s/keV/cm2 at 30 keV for PIN; energy resolutions of 2.9 keV (PIN diode, at 59.5 keV) and 10% (GSO scintillator, at 662 keV); and low energy thresholds of 10 keV for PIN diodes and 30 keV for GSO scintillators. The measured background predicts a continuum sensitivity of a few x 10-6 photons/s/keV/cm2. Anti-Counter units surrounding the HXD-II provide 50 keV-5 MeV information on gamma-ray bursts and bright X-ray transients.
The Hard X-ray Detector (HXD) is one of the three instruments on the fifth Japanese cosmic X-ray satellite ASTRO-E, scheduled for launch in January 2000. The HXD covers a wide energy range of 10-600 keV, using 16 identical GSO/BGO phoswich-counter modules, of which the low-energy efficiency is greatly improved by adding 2 m-thick silicon PIN diodes. Production of the HXD has been completed and pre-flight calibration is now in progress. The design concept of the HXD sensor, detail of the production process, and a brief summary of the measured performance is reported.
The hard x-ray detector (HXD) is one of the three experiments of the Astro-E mission, the fifth Japanese X-ray Satellite devoted to studies of high energy phenomena in the universe in the x-ray to soft gamma-ray region. Prepared for launch at the beginning of 200 via the newly developed M-V launch vehicle of the Institute of Space and Astronomical Science, the Astro-E is to be thrown in to a near-circular orbit of 550 km altitude, with an inclination of 31 degrees. The flight model has been finished assembled this year, and we carried out various tests to verify the performance. We acquired the background spectrum at sea level, and confirmed that our system is operating effectively in reducing the background level. The HXD will observe photons in the energy range of 10-600 keV, and the calculations based on the preflight calibration suggest that the HXD will have the highest sensitivity ever achieved in this energy range. We also verified that our electronic system will maintain its performance against charged particle events expected in orbit.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.