Publisher's Note: This paper, originally published on 22 August 2024, was replaced with a corrected/revised version on 20 September 2024. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.
KEYWORDS: X-rays, Analog electronics, Power supplies, Analog to digital converters, Field programmable gate arrays, X-ray imaging, X-ray detectors, Gamma radiation, Optical sensors
HiZ-GUNDAM is a candidate satellite mission for JAXA to promote time-domain and multi-messenger astronomy as the main targets of gamma-ray bursts. As the mission payload, one of the module of the wide field X-ray monitors consist of a lobster eye optics array and a focal imaging sensor. The field of view of the monitor covers ∼ 0.7 steradian of the sky in the soft X-ray band (0.4 − 4 keV). As the X-ray detector, the pnCCD detector fabricated by PNSensor Inc. can achieve our mission requirements. And we are developing an FPGA-based electronic system for the pnCCD.Our bread-board model of the electronic system consists of (1) a FPGA board, (2) an ADC and power supply board, (3) a pnCCD mounting board, and (4) a 96 × 192-pixel pnCCD read out by 4 CAMEX analog front-end ASICs. We have driven the front-end electronics of the pnCCD successfully by sending the test pulse. In this paper, we report the development status of our FPGA-based electronic system to control the pnCCD sensor.
The KOYOH satellite, launched on December 1, 2023, aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base, is a 50-kg class microsatellite designed to advance the understanding of short gamma-ray bursts (GRBs) and their association with gravitational wave (GW) events. The satellite operates in a Sun-Synchronous Orbit (SSO), equipped with the Transient Localization Experiment (T-LEX) and the Gamma-ray Detector (KGD). T-LEX, a wide-field X-ray imaging detector, and KGD, a wide-field gamma-ray detector, are designed to detect and localize GRBs and other high-energy transients. Following its launch and initial deployment, the satellite successfully established communication links and confirmed the operational status of its subsystems. Initial telemetry data verified the deployment of the Solar Array Paddles (SAP) and correct orientation towards the Sun. The satellite’s power systems were confirmed to be functioning nominally. Subsequent tests established the functionality of the mission instruments. The KGD exhibited a count rate of about 300-500 counts/sec at low latitudes, while T-LEX showed a count rate of approximately 200-300 counts/sec in total. These initial results confirm the successful detection of X-ray and gamma-ray photons by both instruments in orbit. This paper details the design, launch, initial operations, and early mission results of the KOYOH satellite, highlighting its contributions to multi-messenger astronomy.
KEYWORDS: Field programmable gate arrays, X-rays, Analog electronics, Power supplies, Image sensors, Analog to digital converters, CMOS sensors, X-ray imaging, Satellites, Charge-coupled devices
Gamma-ray bursts (GRBs) are the most luminous explosions in the universe, emitting energy on the order of 1052 to 1054 erg over several tens of milliseconds to a few hundred seconds. HiZ-GUNDAM is a future satellite mission designed to explore the early universe using GRBs as probes. It utilizes a wide-field X-ray monitor consisting of Lobster Eye Optics (LEO) and focal image sensors, which detect and determine the direction of GRBs. Two candidates for the focal plane detector are CMOS image sensors and pnCCD image sensors. In the past, we developed the CAPREO FPGA board for the high-speed readout and X-ray event extraction of CMOS image sensors. Currently, we are developing the drive and readout system for the pnCCD, the another candidate. PNSensor’s pnCCD detector, which features a fast readout, large area, and high sensitivity, meets the mission requirements, including an imaging area of 55 mm × 55 mm or larger, a frame rate of at least 10 fps, and a pixel size of approximately 100 μm. The pnCCD drive and readout system requires functions for generating the drive signals for the pnCCD and for AD conversion of the analog signals from the pnCCD. The CAPREO FPGA system can be adapted for high-speed readout and X-ray event extraction. To implement these functions, we developed the PHI driver board to generate charge transfer signals for the pnCCD, the ADC board to convert analog signals from the pnCCD, and a power supply board to power this system. In this paper, we first provide an overview of HiZ-GUNDAM and the mission requirements for the focal plane detector, followed by an introduction to the functions of the three electronic boards we developed.
PETREL (Platform for Extra & Terrestrial Remote Examination with LCTF) is a 50kg class satellite with a 80mm-diameter Ultraviolet Telescope (UVT). The science missions of the UVT system are the discovery of high-energy transients, such as supernovae and gravitational-wave electromagnetic sources. To achieve them, the optical system is optimized to detect near-UV photons between 250 and 300 nm. Within a 30-minutes exposure time per every revolution, it surveys a remarkably wide field as 50 deg^2 with a high sensitivity of 20~ AB magnitude. The Board Unit has an on-board computer, which directly analyzes raw images obtained by a back-illuminated CMOS sensor. The computer can detect transients immediately, so as to alert the transient information to ground within 30 minutes of discovery. We will achieve the first UV survey to explore the transients in their early phase and reveal the underlying physical processes.
HiZ-GUNDAM is a future satellite mission whose mission concept was approved by ISAS/JAXA, and it is one of the future satellite candidates of JAXA’s competitive medium-class mission. HiZ-GUNDAM will lead time-domain astronomy in 2030s, and its key sciences are (1) exploration of the early universe with high-redshift gamma-ray bursts, and (2) contribution to the multi-messenger astronomy. Two mission payloads are aboard HiZ-GUNDAM to realize these two scientific issues. The wide field X-ray monitors which consist of Lobster Eye optics array and focal imaging sensor, monitor ~0.5 steradian field of view in 0.5–4 keV energy range. The near infrared telescope with an aperture size of 30 cm in diameter performs simultaneous 5-band photometric observation in 0.5–2.5 μm wavelength with Koester’s prism for X-ray transients discovered by Wide Field X-ray Monitor. In this paper, we introduce the mission overview of HiZ-GUNDAM while the information contained herein may change in future studies.
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 0.6 steradian at 0.4–4.0 keV, consisting of Lobster Eye Optics (LEO) and pnCCD image sensors. LEOs need to be spatially well-aligned to achieve both of wide FoV and fine position accuracy of < 3 arcmin. To address this challenge, we explored an alignment method with X-rays and developed an optical frame. This study reports on the evaluation of the optical frame, our alignment method, and x-ray performance of the optical system.
We are developing a wide-field X-ray monitor onboard the HiZ-GUNDAM mission. HiZ-GUNDAM is a future satellite mission for gamma-ray burst observation to lead the time domain astronomy and multi-messenger astronomy. The pnCCD detectors will be used as a focal plane detector, which is a back-illuminated CCD and fully depleted by reverse-biased pn-junctions on front and back sides. It has a high sensitivity to low-energy X-rays and achieves a high frame rate with column-parallel readout. It was originally developed for X-ray astronomy, and its high radiation hardness has been verified on satellites such as the XMM-Newton and the eRosita mission. The detector temperature is assumed to be around −20 °C, which is higher than that of usual space use CCD sensors, due to thermal design constraints.
We investigated the spectral performance of pnCCDs using a small-sized device mounted on the camera system manufactured by PNDetector GmbH. Several fluorescence X-ray lines from 0.28 keV(C-Kα) to 4.5keV (Ti-Kα) were used for measurements. The energy resolution of 52 eV for 0.28 keV was verified, with a frame rate of 100 Hz at −20 °C of operating temperature. We also made measurements of dark current for various temperatures ranging from −20 to 0 °C and evaluated that the lower discriminated energy could be 123 eV even at 0 °C. These results verified to satisfy the mission requirements of HiZ-GUNDAM.
The HiZ-GUNDAM mission is one of the candidates for the JAXA’s competitive M-class missions. HiZ-GUNDAM revolutionizes our understanding of the high redshift universe and promotes multi-messenger astronomy. Combining a highly sensitive wide-field X-ray monitor, a near-infrared telescope, and autonomous spacecraft slew capability makes a powerful machine to hunt interesting X-ray transients and immediately identify their counterparts in near-infrared. The Wide Field X-ray Monitor (WFXM) is the main instrument to search for the transients in the soft X-ray band. WFXM comprises lobster-eye optics (LEO) and pnCCD as an X-ray imager. LEO has a size of 40 mm x 40 mm and a radius of curvature of 600 mm. We are planning to use the LEO manufactured by Photonis Inc. One WFXM module has three by three LEOs, which cover a field of view of 12 deg x 12 deg. The current baseline design is composed of 16 modules to cover 0.7 sr sky. The candidate focal imager is the pnCCD detector by PNSensor Inc. We will present the current status and prospects of the WFXM.
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.
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.
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.
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.
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.
KEYWORDS: Avalanche photodetectors, X-rays, Field effect transistors, Resistance, Crystals, Sensors, Hard x-rays, Scintillators, Analog electronics, Stanford Linear Collider
WF-MAXI is a mission to detect and localize X-ray transients with short-term variability as gravitational-wave (GW) candidates including gamma-ray bursts, supernovae etc. We are planning on starting observations by WF-MAXI to be ready for the initial operation of the next generation GW telescopes (e.g., KAGRA, Advanced LIGO etc.). WF-MAXI consists of two main instruments, Soft X-ray Large Solid Angle Camera (SLC) and Hard X-ray Monitor (HXM) which totally cover 0.7 keV to 1 MeV band. HXM is a multi-channel array of crystal scintillators coupled with APDs observing photons in the hard X-ray band with an effective area of above 100 cm2. We have developed an analog application specific integrated circuit (ASIC) dedicated for the readout of 32-channel APDs' signals using 0.35 μm CMOS technology based on Open IP project and an analog amplifier was designed to achieve a low-noise readout. The developed ASIC showed a low-noise performance of 2080 e- + 2.3 e-/pF at root mean square and with a reverse-type APD coupled to a Ce:GAGG crystal a good FWHM energy resolution of 6.9% for 662 keV -rays.
WF-MAXI is a soft X-ray transient monitor proposed for the ISS/JEM. Unlike MAXI, it will always cover a large field of view (20 % of the entire sky) to detect short transients more efficiently. In addition to the various transient sources seen by MAXI, we hope to localize X-ray counterparts of gravitational wave events, expected to be directly detected by Advanced-LIGO, Virgo and KAGRA in late 2010's. The main instrument, the Soft X-ray Large Solid Angle Cameras (SLC) is sensitive in the 0.7-12 keV band with a localization accuracy of ~ 0:1°. The Hard X-ray Monitor (HXM) covers the same sky field in the 20 keV-1 MeV band.
To measure the polarization of gamma-ray bursts in X-ray energy band, we have developed a 50 kg micro-satellite named "SUBAME". The satellite has a compact and high-sensitive hard X-ray polarimeter employing newly-developed shock resistant multi-anode photomultipliers and Si avalanche photodiodes. Thanks to the ultra low-noise detectors and signal processors, the polarimeter can cover a wide energy range of 30200 keV even at 25°C with a high modulation factor of 62 %. TSUBAME is in the phase of final functional tests waiting for shipping to Baikonur and will be launched into a sun-synchronous orbit at an altitude of 700 km in late 2014. In this paper, the pre-ight performance of the gamma-ray detector system and the satellite bus system are presented.
Wide-Field MAXI (WF-MAXI) planned to be installed in Japanese Experiment Module “Kibo” Exposed Facility of the international space station (ISS). WF-MAXI consists of two types of cameras, Soft X-ray Large Solid Angle Camera (SLC) and Hard X-ray Monitor (HXM). HXM is multi-channel arrays of CsI scintillators coupled with avalanche photodiodes (APDs) which covers the energy range of 20 - 200 keV. SLC is arrays of CCD, which is evolved version of MAXI/SSC. Instead of slit and collimator in SSC, SLC is equipped with coded mask allowing its field of view to 20% of all sky at any given time, and its location determination accuracy to few arcminutes. In older to achieve larger effective area, the number of CCD chip and the size of each chip will be larger than that of SSC. We are planning to use 59 x 31 mm2 CCD chip provided by Hamamatsu Photonics. Each camera will be quipped with 16 CCDs and total of 4 cameras will be installed in WF-MAXI. Since SLC utilize X-ray CCDs it must equip active cooling system for CCDs. Instead of using the peltier cooler, we use mechanical coolers that are also employed in Astro-H. In this way we can cool the CCDs down to -100C. ISS orbit around the earth in 90 minutes; therefore a point source moves 4 arcminutes per second. In order to achieve location determination accuracy, we need fast readout from CCD. The pulse heights are stacked into a single row along the vertical direction. Charge is transferred continuously, thus the spatial information along the vertical direction is lost and replaced with the precise arrival time information. Currently we are making experimental model of the camera body including the CCD and electronics for the CCDs. In this paper, we show the development status of SLC.
The Polarized Gamma-ray Observer (PoGO) is a new balloon-borne instrument designed to measure polarization from astrophysical objects in the 30-200 keV range. It is under development for the first flight anticipated in 2008. PoGO is designed to minimize the background by an improved phoswich configuration, which enables a detection of 10 % polarization in a 100 mCrab source in a 6--8 hour observation. To achieve such high sensitivity, low energy response of the detector is important because the source count rate is generally dominated by the lowest energy photons. We have developed new PMT assemblies specifically designed for PoGO to read-out weak scintillation light of one photoelectron (1 p.e.) level. A beam test of a prototype detector array was conducted at the KEK Photon Factory, Tsukuba in Japan. The experimental data confirm that PoGO can detect polarization of 80-85 % polarized beam down to 30 keV with a modulation factor 0.25 ± 0.05.
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.