PSF-like Alpha-Particle Events in LSST Images
Fuente:
arXiv
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| Autori principali: | , , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| author | Homar, Guillem Megias Lage, Craig S. Léget, Pierre-François Kahn, Steven M. Stubbs, Christopher W. Kulkarni, S. R. Sullivan, Ian S. Bosch, James F. Rykoff, Eli S. |
| author_facet | Homar, Guillem Megias Lage, Craig S. Léget, Pierre-François Kahn, Steven M. Stubbs, Christopher W. Kulkarni, S. R. Sullivan, Ian S. Bosch, James F. Rykoff, Eli S. |
| contents | Rare $α$-particle-induced charge clusters appear in LSST images as compact, PSF-like sources with a median FWHM of $0.\!\!^{\prime\prime}95$ and median ellipticity consistent with zero, closely resembling unresolved astrophysical point sources. These events are detected in both dark and science exposures at a rate of approximately $10^{-12}\ \mathrm{pixel}^{-1}\ \mathrm{s}^{-1}$. Their collected charge and morphology are consistent with energy deposition from $\sim$5 MeV $α$-particles in silicon CCDs, and their spatial distribution across the focal plane suggests a localized material origin, plausibly associated with trace radioactive contamination in the cryostat aluminum. Despite their deceptive appearance, we demonstrate that a simple broadness statistic based on fourth-order moments cleanly separates these events from stellar PSFs, enabling efficient rejection in coadded images and real-time alert streams. Such charge clusters do not impose an intrinsic bright-end contamination floor for Rubin transient searches, as genuine fast astrophysical events would exhibit characteristically different morphological signatures. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2606_01295 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | PSF-like Alpha-Particle Events in LSST Images Homar, Guillem Megias Lage, Craig S. Léget, Pierre-François Kahn, Steven M. Stubbs, Christopher W. Kulkarni, S. R. Sullivan, Ian S. Bosch, James F. Rykoff, Eli S. Instrumentation and Methods for Astrophysics Instrumentation and Detectors Rare $α$-particle-induced charge clusters appear in LSST images as compact, PSF-like sources with a median FWHM of $0.\!\!^{\prime\prime}95$ and median ellipticity consistent with zero, closely resembling unresolved astrophysical point sources. These events are detected in both dark and science exposures at a rate of approximately $10^{-12}\ \mathrm{pixel}^{-1}\ \mathrm{s}^{-1}$. Their collected charge and morphology are consistent with energy deposition from $\sim$5 MeV $α$-particles in silicon CCDs, and their spatial distribution across the focal plane suggests a localized material origin, plausibly associated with trace radioactive contamination in the cryostat aluminum. Despite their deceptive appearance, we demonstrate that a simple broadness statistic based on fourth-order moments cleanly separates these events from stellar PSFs, enabling efficient rejection in coadded images and real-time alert streams. Such charge clusters do not impose an intrinsic bright-end contamination floor for Rubin transient searches, as genuine fast astrophysical events would exhibit characteristically different morphological signatures. |
| title | PSF-like Alpha-Particle Events in LSST Images |
| topic | Instrumentation and Methods for Astrophysics Instrumentation and Detectors |
| url | https://arxiv.org/abs/2606.01295 |