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.
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.
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.
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.
X-ray observation covering a wide field of view with a good sensitivity is essential to search for an electromagnetic counterpart of gravitational wave events. A lobster-eye optics (LEO) and a large area CMOS sensor are good instruments to achieve this goal. Furthermore, thanks to the light weight of LEO, it is possible to install on a small platform such as a CubeSat. However, real-time identification of x-ray events is challenging to perform in the restricted resources. Therefore, we utilize one of the machine learning models of convolutional neural network (CNN) to extract x-ray events in the image taken from a CMOS sensor. Moreover, we use a Sony micro board computer, Spresense, ultra-low power consumption, and supports machine learning libraries for the process. This presentation will introduce our machine learning-based x-ray event selection process targeting to use for a CubeSat.
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.