Paresh Chandra Pradhan

Development of High‐Performance Multilayer Monochromators

Wadwan Singhapong, Arindam Majhi, Wai Jue Tan, Vishal P. Dhamgaye et autres

Abstract Multilayer monochromators are crucial optical elements for monochromatizing intense X‐ray beams in applications demanding high photon flux with moderate energy resolution. Achieving high‐performance multilayer monochromators requires optimizing multilayer parameters, using high‐quality substrates, and precisely controlling the deposition process to ensure high …

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Development of multilayer monochromators for stripe-free X-ray imaging

Riley Shurvinton, Paresh Chandra Pradhan, Murilo Bazan Da Silva, Wadwan Singhapong et autres

Multilayer (ML) monochromators are essential components in synchrotron radiation facilities, widely used for X-ray imaging and X-ray diffraction, as well as select X-ray spectroscopy techniques. However, ML monochromators introduce stripe artefacts to the reflected beam, which degrade the quality of the X-ray …

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High-luminosity meV-resolution single-shot hard X-ray spectrograph for cavity-based X-ray free-electron lasers

Keshab Kauchha, Peifan Liu, Paresh Chandra Pradhan, Yuri V. Shvyd'ko

Cavity-based X-ray free-electron lasers (CBXFELs) represent a possible realization of fully coherent hard X-ray sources having high spectral brilliance along with a narrow spectral bandwidth of ∼1–50 meV, a high repetition pulse rate of ∼1 MHz, and good stability. A diagnostic tool …

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Ultra-high precision NiP mirror fabrication using ion beam figuring for space applications

Paresh Chandra Pradhan, Riley Shurvinton, Cyril J. Bourgenot, Hongchang Wang et autres

Nickel phosphorous (NiP) is a broadly used optical material for wide-field visible to mid-infrared instrumentation in space applications. The process chain usually involves applying an electroless metal deposition onto a mirror substrate, which is then machined by single-point diamond turning (SPDT). However, …

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Multi-wavelength study of 1eRASS J085039.9−421151 with eROSITA, NuSTAR, and X-shooter

A. Zainab, A. Avakyan, Victor Doroshenko, P. Thalhammer et autres

The eROSITA instrument on board Spectrum-Roentgen-Gamma (SRG) has completed four scans of the X-ray sky, leading to the detection of almost one million X-ray sources in eRASS1 alone, including multiple new X-ray binary candidates. We report on analysis of the X-ray binary …

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X-ray diagnostics for the cavity-based x-ray free-electron laser project

Peifan Liu, Paresh Chandra Pradhan, Antonino Miceli, Donald A. Walko et autres

The success of x-ray free-electron lasers (XFELs) in recent years has greatly advanced many scientific fields. However, most of these XFELs suffer from a low longitudinal coherence and instabilities due to the stochastic start-up process. A cavity-based x-ray free-electron laser (CBXFEL) is …

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Compact freeform 3 mirrors telescope for CubeSat within an additively manufactured housing (Conference Presentation)

Cyril J. Bourgenot, Joel Coukham, David G. Bramall, Paul White et autres

This paper reports on a nested freeform Three Mirror Anastigmat (TMA) telescope designed for a 3U CubeSat, achieving a compact 1.5U form factor with a focal length of 500mm, F/4.6. Capable of near-diffraction-limited performance in a 0.37°x0.42° field of view, it provides …

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Rapid Mid-Infrared Spectral-Timing with JWST. I. The prototypical black hole X-ray Binary GRS 1915+105 during a MIR-bright and X-ray-obscured state

P. Gandhi, E. S. Borowski, John W. Byrom, R. I. Hynes et autres

We present mid-infrared (MIR) spectral-timing measurements of the prototypical Galactic microquasar GRS 1915+105. The source was observed with the Mid-Infrared Instrument (MIRI) onboard JWST in June 2023 at a MIR luminosity L(MIR)~10^{36} erg/s exceeding past IR levels by about a factor of …

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The giant outburst of EXO 2030+375 II: Broadband spectroscopy and evolution

Ralf Ballhausen, P. Thalhammer, Paresh Chandra Pradhan, E. Sokolova-Lapa et autres

In 2021, the high-mass X-ray binary EXO 2030+375 underwent a giant X-ray outburst, the first since 2006, that reached a peak flux of ${\sim}600\,\mathrm{mCrab}$ (3-50\,keV). The goal of this work is to study the spectral evolution over the course of the outburst, …

Sub-nanometre quality X-ray mirrors created using ion beam figuring

Arindam Majhi, Riley Shurvinton, Paresh Chandra Pradhan, Matthew Hand et autres

Ion beam figuring (IBF) is a powerful technique for figure correction of X-ray mirrors to a high accuracy. Here, recent technical advancements in the IBF instrument developed at Diamond Light Source are presented and experimental results for figuring of X-ray mirrors are …

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X-ray optics for the cavity-based X-ray free-electron laser

Peifan Liu, Paresh Chandra Pradhan, Xianbo Shi, Deming Shu et autres

A cavity-based X-ray free-electron laser (CBXFEL) is a possible future direction in the development of fully coherent X-ray sources. CBXFELs consist of a low-emittance electron source, a magnet system with several undulators and chicanes, and an X-ray cavity. The X-ray cavity stores …

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The giant outburst of EXO 2030+375 I: Spectral and pulse profile evolution

P. Thalhammer, Ralf Ballhausen, E. Sokolova-Lapa, J. Stierhof et autres

The Be X-ray binary EXO 2030+375 went through its third recorded giant outburst from June 2021 to early 2022. We present the results of both spectral and timing analysis based on NICER monitoring, covering the 2-10 keV flux range from 20 to …