![[PukiWiki]](image/pukiwiki.png "[PukiWiki]")
Language: 英語 (English)
Abstract: NASA’s Habitable World Observatory (HWO) will observe faint sources in ultralow (photon-per-hour) backgrounds. In this talk, we present NASA-funded research to advance single-photon counting and radiation-tolerant CMOS detectors for NASA missions, in particular, those requiring optical/UV photon counting detectors. In the project, we will measure the performance of Fairchild Imaging large-format single photon counting and photon number resolving CMOS imaging detectors (HWK4123) before and after radiation that simulates the environment at L2. These detectors have very low capacitance sense nodes to produce a large voltage response to a single photon. In a predecessor project, we found that performance for a similar detector (QIS, Gigajot Technologies) is little-changed after exposure to 50 krad(Si). The dark current can be set to beginning-of-life levels with modest additional cooling, 4–6 K for an 11-year mission. The project seeks to minimize the transient and long-term effects of radiation in NASA missions and also to design a single photon counting and photon number resolving NIR detector with similar architecture.
Language: 英語 (English)
Abstract: Most disc galaxies go through an early epoch of being "gas rich," an era that is being actively explored today through ALMA and JWST observations. This high gas-fraction phase got going much sooner (z > 3) than anticipated by cosmological N-body simulations. A new class of controlled (Nexus) simulations of these early times reveals that these turbulent discs have extraordinary properties. Unexpectedly, m=2,3 spiral arms, stellar and gaseous bars, even X-shaped/peanut bulges, all form under these conditions. The high gas content accelerates stellar migration and stabilizes the disc against buckling. Moreover, baryon sloshing driven by strong feedback gives rise to thick stellar discs, a likely origin of alpha-enriched thick stellar discs observed today. The sloshing gives rise to specific signatures that may already be observable in ALMA data. We discuss the implications of the new work on galaxy studies.
