Dr. Paul E. J. Nulsen Profile

Dr. Paul E. J. Nulsen

at Smithsonian Astrophysical Observatory

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Author

Publications (9)

Proceedings Article | 31 August 2022 Poster + Paper

Reducing the background in x-ray imaging detectors via machine learning

D. Wilkins, S. Allen, E. Miller, M. Bautz, T. Chattopadhyay, R. Foster, C. Grant, S. Herrmann, R. Kraft, R. G. Morris, P. Nulsen, G. Schellenberger

Proceedings Volume 12181, 121816S (2022) https://doi.org/10.1117/12.2629496

KEYWORDS: X-rays, Sensors, Evolutionary algorithms, Detection and tracking algorithms, X-ray detectors, Particles, Machine learning, X-ray imaging, Algorithm development, Image sensors

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SPIE Journal Paper | 15 February 2022 Open Access

Mitigating the effects of particle background on the Athena Wide Field Imager

Eric Miller, Catherine Grant, Marshall Bautz, Silvano Molendi, Ralph Kraft, Paul Nulsen, Esra Bulbul, Steven Allen, David Burrows, Tanja Eraerds, Valentina Fioretti, Fabio Gastaldello, David Hall, Michael W. Hubbard, Jonathan Keelan, Norbert Meidinger, Emanuele Perinati, Arne Rau, Dan Wilkins

JATIS, Vol. 8, Issue 01, 018001, (February 2022) https://doi.org/10.1117/12.10.1117/1.JATIS.8.1.018001

KEYWORDS: Particles, Signal to noise ratio, Sensors, Camera shutters, Signal attenuation, Imaging systems, Signal detection, X-rays, Photons, X-ray imaging

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The Wide Field Imager (WFI) flying on Athena will usher in the next era of studying the hot and energetic Universe. Among Athena’s ambitious science programs are observations of faint, diffuse sources limited by statistical and systematic uncertainty in the background produced by high-energy cosmic ray particles. These particles produce easily identified “cosmic-ray tracks” along with less easily identified signals produced by secondary photons or x-rays generated by particle interactions with the instrument. Such secondaries produce identical signals to the x-rays focused by the optics and cannot be filtered without also eliminating these precious photons. As part of a larger effort to estimate the level of unrejected background and mitigate its effects, we here present results from a study of background-reduction techniques that exploit the spatial correlation between cosmic-ray particle tracks and secondary events. We use Geant4 simulations to generate a realistic particle background signal, sort this into simulated WFI frames, and process those frames in a similar way to the expected flight and ground software to produce a realistic WFI observation containing only particle background. The technique under study, self-anti-coincidence (SAC), then selectively filters regions of the detector around particle tracks, turning the WFI into its own anti-coincidence detector. We show that SAC is effective at improving the systematic uncertainty for observations of faint, diffuse sources, but at the cost of statistical uncertainty due to a reduction in signal. If sufficient pixel pulse-height information is telemetered to the ground for each frame, then this technique can be applied selectively based on the science goals, providing flexibility without affecting the data quality for other science. The results presented here are relevant for any future silicon-based pixelated x-ray imaging detector and could allow the WFI and similar instruments to probe to truly faint x-ray surface brightness.

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Proceedings Article | 13 December 2020 Presentation + Paper

Identifying charged particle background events in x-ray imaging detectors with novel machine learning algorithms

D. Wilkins, S. Allen, E. Miller, M. Bautz, T. Chattopadhyay, S. Fort, C. Grant, S. Herrmann, R. Kraft, R. G. Morris, P. Nulsen

Proceedings Volume 11444, 114442O (2020) https://doi.org/10.1117/12.2562354

KEYWORDS: X-rays, Sensors, Particles, X-ray detectors, Detection and tracking algorithms, X-ray imaging, Neural networks, Signal detection, Space operations

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Proceedings Article | 13 December 2020 Poster + Paper

Reducing the Athena WFI charged particle background: results from Geant4 simulations

Catherine Grant, Eric Miller, Marshall Bautz, Tanja Eraerds, Silvano Molendi, Jonathan Keelan, David Hall, Andrew Holland, Ralph Kraft, Esra Bulbul, Paul Nulsen, Steven Allen

Proceedings Volume 11444, 1144442 (2020) https://doi.org/10.1117/12.2561124

KEYWORDS: Particles, X-rays, Imaging systems, X-ray imaging, Observatories, Galaxy groups and clusters, Detection and tracking algorithms, Silicon, X-ray detectors, Aerospace engineering

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Proceedings Article | 9 September 2019 Paper

US Contributions to the Athena Wide Field Imager

David Burrows, Steve Allen, Marshall Bautz, Esra Bulbul, Tanmoy Chattopadhyay, Julia Erdley, Abraham Falcone, Catherine Grant, Sven Herrmann, Ann Hornschemeier, Doug Kelly, Jamie Kennea, Ralph Kraft, Beverly LaMarr, Adam Mantz, Eric Miller, R. Glenn Morris, Paul Nulsen, Pragati Pradhan, Neven Vulic, Dan Wilkins, Michael Zugger

Proceedings Volume 11118, 111180Z (2019) https://doi.org/10.1117/12.2528532

KEYWORDS: Scanning probe microscopy, Image processing, Target detection, Software development, Algorithm development, Imaging systems, X-rays, X-ray sources

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Proceedings Article | 6 July 2018 Paper

Reducing the ATHENA WFI background with the science products module: lessons from Chandra ACIS

Catherine Grant, Eric Miller, Marshall Bautz, Esra Bulbul, Ralph Kraft, Paul Nulsen, David Burrows, Steven Allen

Proceedings Volume 10699, 106994H (2018) https://doi.org/10.1117/12.2313864

KEYWORDS: Particles, X-rays, Charge-coupled devices, Calibration, Sensors, X-ray imaging, X-ray detectors, Observatories, Correlation function, Astrophysics

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Proceedings Article | 6 July 2018 Paper

Characterizing particle background of ATHENA WFI for the science products module: swift XRT full frame and XMM-PN small window mode observations

Esra Bulbul, Ralph Kraft, Paul Nulsen, Eric Miller, Catherine Grant, Mark Bautz, David Burrows, Steven Allen

Proceedings Volume 10699, 106994G (2018) https://doi.org/10.1117/12.2313717

KEYWORDS: Particles, X-rays, Charge-coupled devices, Sensors, X-ray telescopes, Scanning probe microscopy, Observatories, Data analysis, Astrophysics, Physics

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Proceedings Article | 6 July 2018 Paper

The ATHENA WFI science products module

David Burrows, Steven Allen, Marshall Bautz, Esra Bulbul, Julia Erdley, Abraham Falcone, Stanislav Fort, Catherine Grant, Sven Herrmann, Jamie Kennea, Robert Klar, Ralph Kraft, Adam Mantz, Eric Miller, Paul Nulsen, Steve Persyn, Pragati Pradhan, Dan Wilkins

Proceedings Volume 10699, 106991J (2018) https://doi.org/10.1117/12.2312785

KEYWORDS: Sensors, Particles, X-rays, Software development, Device simulation, Algorithm development, Image processing

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Proceedings Article | 6 July 2018 Presentation + Paper

Two decades of Chandra high-resolution camera operations: lessons learned and future prospects

Ralph Kraft, Paul Nulsen, Grant Tremblay, Daniel Patnaude, Almus Kenter, Thomas Gauron, Gerald Austin, Esra Bulbul, Linda Parker, Ronald Elsner, Stephen O'Dell, Joseph Minow, Stephen Murray

Proceedings Volume 10699, 106991T (2018) https://doi.org/10.1117/12.2314284

KEYWORDS: Microchannel plates, Sensors, X-rays, Scattering, Particles, Telescopes, Ultraviolet radiation, Space operations, X-ray detectors

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Showing 5 of 9 publications

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