Dr. Simon R. Bandler Profile

Dr. Simon R. Bandler

Research Scientist at NASA Goddard Space Flight Ctr

SPIE Involvement:

Author

Publications (47)

PROCEEDINGS ARTICLE | July 31, 2018

The ATHENA X-ray Integral Field Unit (X-IFU)

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Optical filters, Mirrors, Electronics, Sensors, X-rays, X-ray sources, Spectral resolution, Wind energy, X-ray astronomy, Cryogenics

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PROCEEDINGS ARTICLE | July 10, 2018

Time- and code-division SQUID multiplexing options for ATHENA X-IFU (Conference Presentation)

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Code division multiplexing, Light sources, Sensors, X-rays, Spectrometers, Multiplexing, Gamma radiation, Synchrotrons, Time division multiplexing, Multiplexers

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SQUID Time-Division Multiplexing (TDM) is a technique for the readout of arrays of Transition-Edge Sensors (TESs) for x-ray and gamma-ray science. TDM has been deployed in many recent 250-pixel-scale instruments including at synchrotron light sources and particle-accelerator facilities, as well as in table-top experiments. Two TES spectrometers employing TDM readout will soon be deployed to electron-beam ion-trap facilities. TDM is also under development as a back-up readout option for the X-ray Integral Field Unit (X-IFU) of the Athena satellite mission. The 3,840 TES pixels of the X-IFU will enable efficient, high resolution spectroscopy (2.5 eV FWHM at 7 keV) of extended astrophysical sources. Multiplexing factors of 40 or more sensors per readout column are planned for the X-IFU. To advance the maturity of TDM readout for Athena, we are creating a focal-plane assembly for the readout of 960 TES pixels in a 24 column by 40 row configuration. We will describe the design and experimental progress on this technology demonstrator. In a TDM system, each dc-biased TES has its own first-stage SQUID. Rows of these first-stage-SQUIDs are turned on and off sequentially such that the signal from only one TES at a time per readout column is passed to a series-array SQUID, to a room-temperature preamplifier, and to digital-feedback electronics. Recent implementations of TDM have a row period of 160 ns and non-multiplexed amplifier noise of 0.19 micro-Phi_0/sqrt(Hz) referred to the first-stage SQUID. Some benchmark demonstrations of TDM with x-ray TES sensors include achievement of 2.55 eV FWHM energy resolution at 5.9 keV in a 32-row, 1-column configuration. Here, the fastest slew rates in the TES currents were similar to those of the X-IFU “LPA2” detector model. We have also achieved 2.72 eV FWHM resolution in a 32-row, 6-column configuration that contained 144 high-quality TESs that were similar to the much faster X-IFU “LPA1” pixels. We will describe on-going efforts to read out TDM arrays at the 6x32 scale and larger, as well as efforts to improve the performance of TDM system subcomponents. We will also describe system-level performance metrics such as cross-talk. SQUID Code-Division Multiplexing (CDM) is closely related to TDM but has important performance advantages. CDM and TDM operation are similar with the main difference being that in CDM, all TESs are observed by the multiplexer at all times, with the polarity of the TES signals switched between rows. Because all TESs are observed by the multiplexer at all times, the sqrt(N_rows) noise-aliasing degradation inherent to TDM is eliminated. We are developing flux-summing CDM to be drop-in compatible with existing TDM systems. The most recent CDM implementation has a nonmultiplexed noise level of 0.17 micro-Phi_0/sqrt(Hz) referred to the first-stage SQUID and a row period of 160 ns. We have demonstrated 2.77 eV FWM resolution at 5.9 keV in 32-row, 1-column CDM test.

PROCEEDINGS ARTICLE | July 10, 2018

The Design of the Lynx x-ray microcalorimeter (LXM) (Conference Presentation)

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: X-ray optics, Satellites, Spectroscopy, X-rays, Image resolution, Amplifiers, Oxygen, X-ray imaging, X-ray telescopes, Cryogenics

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Lynx is an x-ray telescope that is one of four large satellite mission concepts currently being studied by NASA to be the next flagship mission. One of Lynx’s three instruments is the Lynx X-ray Microcalorimeter (LXM), an imaging spectrometer placed at the focus of an x-ray optic with 0.5 arc-second angular resolution and approximately 2 m2 area at 1 keV. It will be used for a wide variety of observations, and the driving performance requirements are met through different sub-regions of the array. It will provide an energy resolution of better than 3 eV over the energy range of 0.2 to 7 keV, with pixels sizes that vary in scale from 0.5 to 1 arc-seconds in the inner 5 arc-minute field-of-view, and to 5 arc-seconds in the extended 20 arc-minute field-of-view. The Main Array consists mostly of 1 arc-second pixels in the central 5 arc-minutes with less than 3 eV energy resolution (FWHM) in the energy range of 0.2 to 7 keV. It is enhanced in the inner 1 arc-minute region with 0.5 arc-second pixels that will better sample the point spread function of the X-ray optic. The inner 5 arc-minute region is designed specifically for the observations related to cosmic feedback studies, investigating the interactions of AGN with the local regions surrounding them. The 0.5" pixel size allows detailed studies of winds and jets on a finer angular scale. It is also optimized for spatially resolved measurements of cluster cores. The outer regions of the array are designed to operate during a completely different set of observations. The Extended Array will be utilized for surveys over large regions of the sky, the 20 arc-minute field-of-view making it practical to make observations of the soft diffuse emission from larger scale-structure such as extended galaxies, the outer regions of galaxy groups and clusters and also cosmic filaments. This array is optimized for high energy resolution up to 2 keV through the use of thin (0.5 um) gold absorbers. The Ultra-High-Res Array is designed specifically to enable the study turbulent line broadening around individual through the study of the highly ionized oxygen lines. It is optimized for energy resolution for the oxygen VII and VIII lines, with better than 0.4 eV energy resolution. In this paper we present the design of the baseline configuration and the scientific motivation. We discuss the technologies that are being developed for this instrument, in particular the transition-edge sensor (TES) and metallic magnetic calorimeter (MMC) sensor technologies. We place these technologies in the context of the required energy resolution, energy range, pixel size, and count-rate, as well as strategies for the pixel layout and wiring. We will discuss the use of microwave SQUIDs, HEMT amplifiers, and parametric amplifiers for the read-out and the implications for the cryogenic design. We also describe the design of the full instrument, including the strawman cryogenic design, as well as an estimate for the mass, power and data rate.

PROCEEDINGS ARTICLE | July 10, 2018

The focal plane assembly for the ATHENA x-ray integral field unit instrument (Conference Presentation)

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Staring arrays, Observatories, Electronics, Sensors, Particles, X-rays, Superconductors, Spectral resolution, X-ray imaging, Environmental sensing

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PROCEEDINGS ARTICLE | July 10, 2018

Transition-edge sensor array development for the ATHENA x-ray itegral field unit (Conference Presentation)

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Observatories, Telescopes, Sensors, Metals, X-rays, Transition metals, Multiplexing, Spectral resolution, Fused deposition modeling

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The X-ray integral field unit (X-IFU) proposed for ESA’s Athena X-ray observatory will consist of 3840 transition edge sensor (TES) microcalorimeters optimized for the energy range of 0.2 to 12 keV. The instrument will provide unprecedented spectral resolution of ~ 2.5 eV at energies of up to 7 keV and will accommodate photon fluxes of 10’s mcrab (1000’s cps). Over the past two years the baseline configuration has evolved from the original proposal. The current baseline consists of a uniform large pixel array (LPA) of 5” pixels, AC-biased within their superconducting-to-normal transition and read out using frequency domain multiplexing (FDM). The baseline pixel design is approximately a factor of two times slower than in the original concept. High count-rate accommodation, needed for bright point source observations, is now achieved by defocusing the telescope optic to spread the photons over a larger number of pixels. In this paper we report on Mo/Au TES designs that are being optimized to meet the baseline pixel parameters and performance goals. This includes detailed studies on the optimization of the thermal heat sink and the impact of different TES geometries (including TES size and normal metal feature geometries) on the DC-biased transition shape. We discuss how these geometric effects ultimately impact important performance metrics such as energy resolution, decay time, slew-rate and array scale uniformity. Our Mo/Au TESs have historically been designed and optimized for DC-biased operation, however, the primary readout technology uses an AC drive to bias the TES. Depending upon the drive frequency, the AC bias affects the TES transition shape in two ways. Firstly, due to losses from the bias current coupling to metallic components in close proximity to the TES and secondly introducing fine structure in the transition due to Josephson effects. We present latest pixel design optimizations targeted at mitigating these frequency dependent effects in order to achieve commensurate performance with that obtained in the DC case.

PROCEEDINGS ARTICLE | July 6, 2018

Super DIOS: future x-ray spectroscopic mission to search for dark baryons

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Cooling systems, Telescopes, Sensors, Spectroscopy, X-rays, Coating, Space telescopes, Spatial resolution, Microwave radiation, X-ray telescopes

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PROCEEDINGS ARTICLE | July 6, 2018

The performance of the ATHENA X-ray Integral Field Unit

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Optical filters, Mirrors, Electronics, Contamination, Sensors, X-rays, Quantum efficiency, Image resolution, Performance modeling, Device simulation

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PROCEEDINGS ARTICLE | July 6, 2018

ATHENA X-ray Integral Field Unit on-board event processor: analysis of performance of two triggering algorithms

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Detection and tracking algorithms, Photons, X-rays, Reconstruction algorithms, Optimal filtering, Algorithm development, Beryllium

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PROCEEDINGS ARTICLE | July 6, 2018

Testing the X-IFU calibration requirements: an example for quantum efficiency and energy resolution

Proc. SPIE. 10699, Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray

KEYWORDS: Sensors, Calibration, Error analysis, X-rays, Quantum efficiency

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PROCEEDINGS ARTICLE | September 19, 2017

Lynx Mission concept status

Proc. SPIE. 10397, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XX

KEYWORDS: Observatories, X-ray optics, Stars, X-rays, Galactic astronomy, Astrophysics, Environmental sensing, Planetary systems

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PROCEEDINGS ARTICLE | August 26, 2016

Status of the micro-X sounding rocket x-ray spectrometer