The Compton Spectrometer and Imager (COSI) is a NASA funded Small Explorer (SMEX) mission slated to launch in 2027. COSI will house a wide-field gamma-ray telescope designed to survey the entire sky in the 0.2-5 MeV range. Using germanium detectors, the instrument will provide imaging, spectroscopy, and polarimetry of astrophysical sources with excellent energy resolution and degree-scale localization capabilities. In addition to the main instrument, COSI will fly with a student collaboration project known as the Background and Transient Observer (BTO). BTO will extend the COSI bandpass to energies lower than 200 keV, thus enabling spectral analysis across the shared band of 30 keV–2 MeV range. The BTO instrument will consist of two NaI scintillators and student-designed readout electronics. Using spectral information from both the COSI and BTO instruments, physics such as the energy peak turnover in gamma-ray bursts, the characteristics of magnetar flares, and the event frequency of a range of transient phenomena will be constrained. In this paper, we present the expected science returnables from BTO and comment on the shared returnables from the COSI and BTO missions. We include simulations of gamma-ray bursts, magnetar giant flares, and terrestrial gamma-ray flashes using BTO’s spectral response. Additionally, we estimate BTO’s gamma-ray burst detection rate and find that BTO will detect ∼100–150 gamma-ray bursts per year, with at least 10% of the events being sGRB.
KEYWORDS: Sensors, Data acquisition, Solar processes, Clocks, Spatial resolution, Signal attenuation, Data storage, Control systems, Hard x-rays, Rockets
The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment enables hard-X-ray solar observations with high angular resolution, high energy resolution, and high sensitivity using the direct imaging method. The fourth flight, FOXSI-4, aimed for the first-ever focusing imaging spectroscopic observation of a medium to large solar flare in hard X-rays and launched in spring 2024 as part of NASA’s sounding rocket solar flare campaign. For resolving structures in the footpoints and the loop-top of a solar flare, the hard X-ray telescopes, which consist of focal plane detectors and Wolter-I mirrors, are required for high angular resolution of 3 arcseconds with high-count-rate photon detection.
We developed wide-gap CdTe Double-sided Strip Detectors (CdTe-DSDs) for the hard X-ray focal plane detector, which achieved an energy resolution of 1 keV (FWHM) and a high position resolution of 30 Μm with high detection efficiency. We also developed a new onboard data acquisition (DAQ) system with a Raspberry Pi, an FPGA board SPMU-001, and a SpaceWire interface for controlling all CdTe-DSDs and realizing fast readout of the observation data whose counting rate is estimated to be 5000 counts per second. The observation data is written in a 128 MB data ring buffer region for temporary storage. The software in the Raspberry Pi controls each detector by the commands from a ground-based computer and simultaneously reads the data at 0.6 Mbps for storage in the DAQ. Some essential data for operation, for example, light curves, energy spectrum, and the status of the DAQ system, is sent to the ground-based computer through the onboard control system.
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.