arXiv subjects

Andrew Malonis

Publications and source records attributed to Andrew Malonis.

23 records · Page 2Linked to original sources

arXiv2021

First results on SiSeRO (Single electron Sensitive Read Out) devices -- a new X-ray detector for scientific instrumentation

We present an evaluation of a novel on-chip charge detector, called the Single electron Sensitive Read Out (SiSeRO), for charge-coupled device (CCD) image sensor applications. It uses a p-MOSFET transistor at the output stage with a depleted internal gate beneath the p-MOSFET. Charge transferred to the internal gate modulates the source-drain current of the transistor. We have developed a drain current readout module to characterize the detector. The prototype sensor achieves a charge/current conversion gain of 700 pA per electron, an equivalent noise charge (ENC) of 15 electrons (e-) root mean square (RMS), and a full width half maximum (FWHM) of 230 eV at 5.9 keV. In this paper, we discuss the SiSeRO working principle, the readout module developed at Stanford, and the first characterization test results of the SiSeRO prototypes. While at present only a proof-of-concept experiment, in the near future we plan to use next generation sensors with improved noise performance and an enhanced readout module. In particular, we are developing a readout module enabling Repetitive Non-Destructive Readout (RNDR) of the charge, which can in principle yield sub-electron ENC performance. With these developments, we eventually plan to build a matrix of SiSeRO amplifiers to develop an active pixel sensor with an on-chip ASIC-based readout system. Such a system, with fast readout speeds and sub-electron noise, could be effectively utilized in scientific applications requiring fast and low-noise spectro-imagers.

astro-ph.IM↗

arXiv2021

Design Requirements for the Wide-field Infrared TransientExplorer (WINTER)

The Wide-field Infrared Transient Explorer (WINTER) is a 1x1 degree infrared survey telescope under development at MIT and Caltech, and slated for commissioning at Palomar Observatory in 2021. WINTER is a seeing-limited infrared time-domain survey and has two main science goals: (1) the discovery of IR kilonovae and r-process materials from binary neutron star mergers and (2) the study of general IR transients, including supernovae, tidal disruption events, and transiting exoplanets around low mass stars. We plan to meet these science goals with technologies that are relatively new to astrophysical research: hybridized InGaAs sensors as an alternative to traditional, but expensive, HgCdTe arrays and an IR-optimized 1-meter COTS telescope. To mitigate risk, optimize development efforts, and ensure that WINTER meets its science objectives, we use model-based systems engineering (MBSE) techniques commonly featured in aerospace engineering projects. Even as ground-based instrumentation projects grow in complexity, they do not often have the budget for a full-time systems engineer. We present one example of systems engineering for the ground-based WINTER project, featuring software tools that allow students or staff to learn the fundamentals of MBSE and capture the results in a formalized software interface. We focus on the top-level science requirements with a detailed example of how the goal of detecting kilonovae flows down to WINTER's optical design. In particular, we discuss new methods for tolerance simulations, eliminating stray light, and maximizing image quality of a fly's-eye design that slices the telescope's focus onto 6 non-buttable, IR detectors. We also include a discussion of safety constraints for a robotic telescope.

astro-ph.IM↗

arXiv2021

The wide-field infrared transient explorer (WINTER)

The Wide-Field Infrared Transient Explorer (WINTER) is a new infrared time-domain survey instrument which will be deployed on a dedicated 1 meter robotic telescope at Palomar Observatory. WINTER will perform a seeing-limited time domain survey of the infrared (IR) sky, with a particular emphasis on identifying r-process material in binary neutron star (BNS) merger remnants detected by LIGO. We describe the scientific goals and survey design of the WINTER instrument. With a dedicated trigger and the ability to map the full LIGO O4 positional error contour in the IR to a distance of 190 Mpc within four hours, WINTER will be a powerful kilonova discovery engine and tool for multi-messenger astrophysics investigations. In addition to follow-up observations of merging binaries, WINTER will facilitate a wide range of time-domain astronomical observations, all the while building up a deep coadded image of the static infrared sky suitable for survey science. WINTER's custom camera features six commercial large-format Indium Gallium Arsenide (InGaAs) sensors and a tiled optical system which covers a $>$1-square-degree field of view with 90% fill factor. The instrument observes in Y, J and a short-H (Hs) band tuned to the long-wave cutoff of the InGaAs sensors, covering a wavelength range from 0.9 - 1.7 microns. We present the design of the WINTER instrument and current progress towards final integration at Palomar Observatory and commissioning planned for mid-2021.

astro-ph.IM↗

arXiv2020

Tiny-box: A tool for the versatile development and characterization of low noise fast X-ray imaging detectors

X-ray Charge Coupled Devices (CCDs) have been the workhorse for soft X-ray astronomical instruments for the past quarter century. They provide broad energy response, extremely low electronic read noise, and good energy resolution in soft X-rays. These properties, along with the large arrays and small pixel sizes available with modern-day CCDs, make them a potential candidate for next generation astronomical X-ray missions equipped with large collecting areas, high angular resolutions and wide fields of view, enabling observation of the faint, diffuse and high redshift X-ray universe. However, such high collecting area (about 30 times Chandra) requires these detectors to have an order of magnitude faster readout than current CCDs to avoid saturation and pile up effects. In this context, Stanford University and MIT have initiated the development of fast readout X-ray cameras. As a tool for this development, we have designed a fast readout, low noise electronics board (intended to work at a 5 Megapixel per second data rate) coupled with an STA Archon controller to readout a 512 x 512 CCD (from MIT Lincoln Laboratory). This versatile setup allows us to study a number of parameters and operation conditions including the option for digital shaping. In this paper, we describe the characterization test stand, the concept and development of the readout electronics, and simulation results. We also report the first measurements of read noise, energy resolution and other parameters from this set up. While this is very much a prototype, we plan to use larger, multi-node CCD devices in the future with dedicated ASIC readout systems to enable faster, parallel readout of the CCDs.

astro-ph.IM↗

arXiv2018

Background-Limited Imaging in the Near-Infrared with Warm InGaAs Sensors: Applications for Time-Domain Astronomy

We describe test observations made with a customized 640 x 512 pixel Indium Gallium Arsenide (InGaAs) prototype astronomical camera on the 100" DuPont telescope. This is the first test of InGaAs as a cost-effective alternative to HgCdTe for research-grade astronomical observations. The camera exhibits an instrument background of 113 e-/sec/pixel (dark + thermal) at an operating temperature of -40C for the sensor, maintained by a simple thermo-electric cooler. The optical train and mechanical structure float at ambient temperature with no cold stop, in contrast to most IR instruments which must be cooled to mitigate thermal backgrounds. Measurements of the night sky using a reimager with plate scale of 0.4 arc seconds / pixel show that the sky flux in Y is comparable to the dark current. At J the sky brightness exceeds dark current by a factor of four, and hence dominates the noise budget. The sensor read noise of ~43e- falls below sky+dark noise for exposures of t>7 seconds in Y and 3.5 seconds in J. We present test observations of several selected science targets, including high-significance detections of a lensed Type Ia supernova, a type IIb supernova, and a z=6.3 quasar. Deeper images are obtained for two local galaxies monitored for IR transients, and a galaxy cluster at z=0.87. Finally, we observe a partial transit of the hot JupiterHATS34b, demonstrating the photometric stability required over several hours to detect a 1.2% transit depth at high significance. A tiling of available larger-format sensors would produce an IR survey instrument with significant cost savings relative to HgCdTe-based cameras, if one is willing to forego the K band. Such a camera would be sensitive for a week or more to isotropic emission from r-process kilonova ejecta similar to that observed in GW170817, over the full 190 Mpc horizon of Advanced LIGO's design sensitivity for neutron star mergers.

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