Wide-field imaging with large-format detectors is crucial for astronomical surveys, particularly in the time-domain era. While CCD and CMOS detectors have been extensively utilized in optical surveys, there is a scarcity of surveys conducted in the infrared bands due to the expensive nature of HgCdTe detectors. However, the InGaAs camera offers a cost-effective alternative for near-infrared imaging. This paper presents the preliminary testing results of a new 1280 × 1024 infrared camera, providing an overview of its performance. Laboratory tests were conducted to determine dark current, readout noise, non-linearity, bias stability, and other parameters. The camera was also mounted on a small telescope for astronomical observations. The potential application of this camera in future time-domain surveys is discussed.

ESA’s Science Payload Validation laboratory is characterising Leonardo’s IBEX detector. IBEX is new 2kx2k pixels MCT-hybridised detector that relies on avalanche photo-diode to provide effective sub-electron readout noise capabilities and low enough dark current compatible with long integration duration typical of photon-starved astronomy applications. In this contribution, we provide first an overview of the packaging solution and test setups including our custom readout chain and prototype controller. We then report on functional and performance test results for a bare-ROIC as well as early dark current performance for the hybridised arrays.

Using disordered superconductors, like β-Ta, TiN, Hf and PtSi, for MKIDs has the potential to improve the photon absorption efficiency, η, over a broad wavelength range. However, the resolving power, R, of these MKIDs is not higher than 20 at 1µm, while the fundamental Fano limit is around 65. To improve R, the signal-to-noise ratio must be increased. We measure the single photon pulse response of β-Ta MKIDs and show that the pulse duration is limited by disorder in two ways. First, the initial pulse decay is faster than exponential, which we attribute to slow quasiparticle diffusion. Second, the decay time of the pulse tail is faster due to low energetic, localized quasiparticles. Both these effects do not occur in conventional Al at the same experimental conditions. These results imply a trade-off between η and R and shows that improving MKIDs by using disordered superconductors is not straightforward.

One of the major goals of modern astronomy is the atmospheric characterization of small exoplanets to learn about their diversity, habitability and ultimately, whether they harbor life. The Large Interferometer For Exoplanets initiative aims to perform atmospheric characterization of these planets in the mid-infrared (MIR) wavelength regime (4 to 18.5 micron). Extremely sensitive and highly efficient detectors are required to detect the faint signal from these small exoplanets. Kinetic Inductance Detectors (KIDs) are a promising candidate as they are able to count single photons with no readout noise or dark current. In this work we experimentally show that KIDs are able to do photon counting at 4 wavelengths between 3.8 and 24 micron. We also compare the performance of two KID designs to investigate what design would be optimal across the MIR band.

Multiple space missions currently under study require high-performing detectors at mid-infrared wavelengths from 2 to 20 µm. However, the future availability of the IBC detectors used for JWST is in doubt, and HgCdTe detectors have difficulties at longer wavelengths. Superconducting detectors are therefore being considered as a solution to fill this technology gap. Superconducting nanowire single-photon detectors (SNSPDs) are particularly advantageous, because they are true photon-counting detectors with digital-like output signals and low dark count rates. These features make them very stable for applications like exoplanet transit spectroscopy and able to operate in photon-starved environments for applications like nulling interferometry. We have recently demonstrated SNSPDs with high internal detection efficiency at wavelengths as long as 29 µm. This talk will provide an overview of the current state of mid-IR SNSPDs and lay out the future steps needed to adapt them for exoplanet science missions.

Here, we introduce the kinetic inductance current sensor (KICS), a novel readout technology based on the nonlinear current dependence of the kinetic inductance in a superconductor. The KICS takes the form of a superconducting resonator with small cross-section inductor, and current input from a TES or similar device causes shifts in the resonant frequency, enabling a sensitive measurement of the TES current. Additionally, the KICS makes use of a superconducting switch, which is used to trap a persistent current in the resonator, reducing noise and bias line pickup and enabling nearly arbitrary frequency tunability. We demonstrate the KICS through the readout of a TES optimized for 1550 nm photon detection, where we measure a resolving power, R, above 5, already matching the performance of a conventional SQUID readout of the same device.

Superconducting detectors have fundamental advantages over conventional optical sensors in terms of noise, sensitivity, energy and time resolution, and radiation tolerance. In this paper, we consider the three most relevant superconducting detector technologies towards the Habitable Worlds Observatory: transition edge sensors (TESs), microwave kinetic inductance detectors (MKIDs), and superconducting nanowire single photon detectors (SNSPDs). We present a reference table providing a quantitative comparison of the three technologies, to help facilitate future trade studies. We also consider instrumental concerns such as low-vibration cryogenics and low-power readout electronics.

The new generation of x-ray and gamma-ray detectors employ cryogenic detectors known as transition-edge sensors (TES) due to their high energy resolution and photon detection rates. These detectors require a refrigeration module that can operate at the transition temperature of the TES’s superconducting film—usually at mK temperatures. DR-TES consists of a novel mini-dilution refrigerator (DR) from Chase Research Cryogenics that can be used in balloon-borne missions to cool detectors to temperatures between 10 to 100mK. To test the viability of this DR module, we will be cooling down a SLEDGEHAMMER detector fabricated by the National Institute of Standards and Technology quantum sensor group. The SLEDGEHAMMER microcalorimeter uses TESs coupled to superconducting quantum interference devices which are in turn coupled to microwave resonators to detect x-rays and gamma-rays. We plan to fly the SLEDGEHAMMER detector cooled by the mini-DR on a stratospheric balloon flight in August of 2024 at Fort Sumner, NM. As a follow-up mission, 511-CAM will use a modified version of the detector to map the 511keV emission from the galactic center region.

We are developing monolithic active pixel sensors, x-ray SOIPIXs based on a Silicon-On-Insulator CMOS technology. Its event trigger output function offers a high time resolution better than ~10 usec. (1) In 2022-23, we and evaluated large sensors, XRPIX-X, with a pixel array size of 14mm x 22mm. We report its design and the results of the performance evaluation. (2) We are developing "Digital X-ray SOIPIXs" for satellite use, featuring on-chip ADCs, DACs, and BGRs for noise robustness. An on-chip clock pattern generator is also included to simplify the readout digital circuits. (3) XRPIXs are increasingly being utilized in various scientific applications beyond x-ray astronomy, and a brief introduction will be provided.

Ability to detect individual photons in the mid-ir is crucial for many astronomical applications and detector technology is the vital part of instrumentation for future space missions. The search for bio signatures through transiting exoplanet spectroscopy requires an array of detectors covering the spectral range of 2.8 to 20μm. Superconducting nanowire single-photon detectors (SNSPDs) are highly efficient and low-noise devices ideal for counting and observing low levels of photons. They have near-perfect quantum efficiency and can be combined into arrays for imaging. Here, we report on the development of 36-pixel mid-infrared SNSPD arrays. Detectors are based on optimised ultrathin NbN films, which are grown by both magnetron sputtering and atomic layer deposition (ALD) techniques. For characterisation we assembled a setup based on tuneable optical parametric oscillator (OPO) source to provide picosecond long pulses in the 1.5 to 10μm spectral region. This work provides an analysis of the electrical, optical, and temporal performance of individual pixels as well as information on pixel performance uniformity across the array.

We present progress towards developing a science-grade, megapixel format linear-mode avalanche photodiode array for low background shortwave (1 - 2.4 um) infrared astronomy. Our latest results show outstanding performance, with dark current <1e-4 electrons/pixel/second and read noise reducing by 30% per volt of bias, reaching less than 1e-/pixel/frame in correlated double-sampling, and able to average down to ~0.3 e-/pixel/frame when using multiple non-destructive reads. We present some on-sky data as well as comment on prospects for photon counting and photon number resolution.

Skipper-CCDs, with their electron-counting capability and low instrumental background, are highly sensitive to faint signals, which is of great interest for certain astronomical applications. Characterizing the instrumental sources of few-e- events in skipper-CCDs is crucial for estimating their scientific reach. In this work I will report on the performance of fully-depleted, p-channel skipper-CCDs, that were fabricated on 8-inch wafers in two new foundries during the R&D of Oscura, a 26 GPix skipper-CCD array designed to search for light dark matter-electron interactions. Results, performed at FNAL, demonstrate a high yield of sensors achieving sub-electron readout noise. Main instrumental sources of few-e- events were identified and characterized, including thermal dark current, spurious charge and charge traps.

The Astro2020 decadal survey envisions a Habitable Worlds Observatory (HWO) for revolutionary advances in exoplanet science, general astrophysics and time domain astronomy in the UV/visible/near IR spectral range. In a project funded by NASA’s Strategic Astrophysics Technology Program, JPL is partnering with industry and academia to fabricate, characterize, and mature CMOS image sensors using nanoscale surface engineering to address technology gaps identified for HWO science. Initial fabrication of delta-doped detectors has been completed, and performance and environmental tests are underway at JPL and Caltech. Columbia University and JPL are developing a CMOS camera for on-sky observations with an integral field spectrograph at MDM Observatory. The University of Colorado is developing engineering designs for incorporating a delta-doped CMOS image sensor in sounding rocket and cubesat payloads. We will present the latest results of our work in support of NASA’s goals for HWO.

The Skipper CCD-in-CMOS image sensor integrates the non-destructive readout capability of skipper Charge Coupled Devices (CCDs) with a high conversion gain pinned photodiode on a CMOS imaging process, while taking advantage of in-pixel signal processing. We will present the first results of the testing of the first prototype ASIC, fabricated in a commercial 180nm CMOS processes, which integrates a pixel matrix as well as individual test structures. Individual pixels in the test structures of the fabricated devices were instrumented to characterize their charge transfer capability and to study their operation in low readout noise conditions. We were able to operate the pixel in single carrier counting mode with deep sub-electron noise to measure charge packets collected by the photodiode when exposed to low illumination levels. Additionally, we will also report on the status of the custom 65nm ASICs prototypes being developed to achieve high speed, sub-electron noise readout. Work supported by the DOE Office of Science under the Microelectronics Co-Design Research Project “Hybrid Cryogenic Detector Architectures for Sensing and Edge Computing enabled by new Fabrication Processes

Charge migration in infrared detectors such as in JWST leads to a 'brighter-fatter effect', where photoelectrons from bright pixels spill to nearby faint pixels and blur the pixel response function at its finest spatial scales - a limiting noise floor for high angular resolution astronomy. We demonstrate an effective forwards model: a nonlinear convolution predicting the effect on every pixel as a polynomial of the pixels in its neighbourhood, learning the coefficients by gradient descent together with a differentiable model of the point spread function. We apply this to the JWST/NIRISS Aperture Masking Interferometer, inferring an accurate model for the BFE in NIRISS; overcoming the main barrier to precise interferometric observations with JWST; and illustrating a simple path to high-quality BFE calibration in other JWST instruments and infrared detectors in general.

Skipper CCDs offer sub-electron readout noise by repetitive non-destructive measurements of signal interleaved with baseline measurements at a high enough frequency to reduce impact of 1/f noise when the average baseline is subtracted from average signal. We describe the design of a Multichannel Video Processor (MVP) board that supports 128 differential video channels of the new Skipper CCD from STA,inc. It is compact enough to be located close to the detector and narrow enough to allow detector mosaics to be supported.

In order to take advantage of data rich focal planes of future space UV and soft x-ray missions, large format detectors with excellent spatial resolution and dynamic range are required. This paper presents the development of photon counting detectors where Timepix readouts are used in combination with Microchannel Plate electron amplifiers enabling photon counting with high spatial (~5µm) and temporal resolution with very large dynamic range (exceeding 10^8 ph/cm^2/s), capable of detection of many simultaneous particles and extended lifetime due to low gain operation. The latest generation of Timepix4 readout is 4-side buttabble enabling high resolution detection of many simultaneous particles (photons, ions, electrons, neutrons) in a large active area.

The x-ray polarization of compact objects in x-ray binaries allows us to understand the complex spacetimes surrounding these sources. XL-Calibur is a state-of-the-art, balloon-borne telescope that measures the linear polarization of stellar-mass black holes, neutron stars, and nebulae in the 15-80 keV energy band. The selected energy range allows for observing coronal emission from black holes while also enabling us to narrow down on emission models from neutron stars, pulsars, and magnetars. Early in 2024, XL-Calibur will be launched from Kiruna, Sweden for approximately 10 days to observe Cyg X-1 and Cyg X-3, or other sources chosen based on flux levels at the time of flight. Observations might be coordinated with the recently launched Imaging x-ray Polarimetry Explorer mission which measures polarization in the complimentary 2-8 keV band. Combined XL-Calibur and IXPE observations will yield information on both soft and hard x-rays allowing us to decompose the total emission from black holes into thermal disk and coronal. We discuss the characterization of the XL-Calibur CdZnTe detectors, the telescope mirror and truss setup, and preliminary results from our most recent flight.

The Mid-InfraRed Instrument (MIRI) uses three Si:As impurity band conduction (IBC) detectors. These detectors make use of an arsenic-doped infrared-active layer to excite photo-electrons and an electric potential applied across the layer guide them to the pixels. The electric potential depletes the layer of electron-hole pairs. As charge accumulates this region shrinks, resulting in more photo-electrons recombining and not reaching the pixels, which produces non-linear voltage integration ramps. On top of this, the spatial and spectral information may be blurred by up to 20% due to charge migration, depending on the contrast between pixels. This ’Brighter-Fatter Effect’ (BFE) has been observed in detectors for optical and near-infrared wavelengths as well, though it manifests differently in the mid-infrared IBC detectors. Since both the non-linearity and BFE are dependent on the amount of charge accumulated, we propose a fitting and correction routine that corrects both simultaneously for all MIRI observing modes.

We are developing imaging Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CZT) pixel detectors with potential applications in hard X-ray astrophysical NASA Explorer and Probe-class missions, utilizing wide field and focusing instruments. Our hybrid sensor consists of a CdTe and a CZT detector with segmented anode contacts directly bonded to an ASIC. We have utilized a custom low-noise, low-power ASIC developed for NuSTAR mission. While NuSTAR employed eV Products CZT detectors, for this study, we used a CdTe detector by Acrorad and a CZT detector by Redlen. Both detectors have anode pixels with a 604-micron pitch in a 32 x 32 array. The CdTe detectors have segmented Schottky blocking contacts, whereas the CZT detectors have plain contacts. Understanding the charge sharing and charge loss behavior between the pixels is crucial to achieve good energy resolutions. In this paper, we report on the study of charge sharing and charge loss effects between the pixels. We will compare the behavior among eV CZT, Redlen CZT, and Acrorad CdTe detectors. Furthermore, we will discuss how these effects might influence smaller pixel pitch detectors for our next-generation prototype ASIC.

ESA’s Science Payload Validation laboratory is developing a new type of detector characterisation bench, designed to cope with new challenges set by future instrument requirements and newly developed detectors. This new bench can accommodate large format detector up to 4kx4k 10um pitch or at least two 2kx2k 15um pitch side by side, it enables measurement in the 300 to 4000nm wavelength range, and can bring the detector temperature down to 20K. Its concept, based on lessons learned accumulated over the last 10 years, enables light and dark measurements to be performed in a single configuration reducing handling and optimising testing time in test campaigns. This contribution provides a general overview of the bench concept and main features. It details the main design challenges and describes the corresponding opto-mechanical and thermal design solutions, validated by early commissioning results.

In this paper we will present characterization of our Microwave Kinetic Inductance Detectors (MKIDs). The design process involved using Sonnet and LEdit 8.3. In this design, we employed a structure consisting of TiN (3nm)/Ti (10nm)/TiN(3nm) layers covered by a 100nm aluminum layer. This structure provides a kinetic inductance of 100 pH/Sqcm and a critical temperature of 1.1 Kelvin. The MKIDs were fabricated on 5-inch silicon wafers with a resistivity exceeding 15000 ohm cm. The designs cover three frequency regimes: 1-2 GHz, 2-4 GHz, and 3-6 GHz. This variation in frequency ranges allows us to study the improvement of quality factors and provides a range of frequencies for testing our electronics.

On-board SVOM to be launched in 2024, the Microchannel X-Ray Telescope (MXT) is equipped with a 256 x 256 pixel pnCCD and two CAMEX ASIC operated at -65°C, and a full-custom front-end electronics box to control the focal plane and extract photon events. Proton irradiation tests were performed on a qualification model of the MXT focal plane and were followed by spectral calibration tests in the SOLEIL synchrotron. The paper will describe the setups of these two campaigns and the performance results, in particular the degradation of charge efficiency transfer and energy resolution by displacement damage dose.

MKIDs made from alternating stacks of Ti and TiN have shown impressive results in far-IR and sub-mm detectors to date, which promises improvements for Optical to Near-IR MKIDs. TiN/Ti/TiN tri-layers offer different advantages between sub-stoichiometric and stoichiometric recipes. We will elaborate on the expected effects of using sub-stoichiometric vs. stoichiometric TiN in triple layers on the wavelength signal-to-noise ratio of MKIDs. We characterise the photon detection performance of TiN/Ti/TiN Optical to Near Infrared MKIDs deposited on silicon wafers. We present measurements of resolving power, quasi-particle lifetime and sensitivity to near-infrared photons with differing pixel fabrication procedures and design.

The traditional readout system for Microwave Kinetic Inductance Detectors (MKID) often utilized Field-Programmable Gate Arrays (FPGAs) for nearly all its digital processing tasks. However, the cost of such FPGA development is high and the design must be conducted carefully to fit the limited FPGA resource. To cope with this challenge, a hybrid readout system emerged as a viable solution, integrating both FPGA and CPU/GPU components. In this configuration, the FPGA handles the hard real-time and high-throughput processing, while a soft CPU/GPU sub-system receives the phase data and executes more sophisticated algorithms. Details of this FPGA firmware and the corresponding CPU/GPU system software developed at Durham University will be presented.

The MARVEL instrument is an array of four 80cm telescopes feeding a high-resolution echelle spectrograph designed to provide high precision radial-velocity measurements and is being led by KU Leuven (Belgium). The UK ATC is responsible for the delivery of the detector work package; a fully characterised STA1600LN optical CCD housed in a custom cryostat. As a large image area detector, the STA1600LN has been used in a variety of astronomy applications for imaging. This paper will detail the characterisation testing done by the UK ATC Electronics and Detectors group, to verify that this detector meets the requirements for a high-resolution spectrograph of this type. Testing includes measures of read noise, dark current, and the effects of the dither clocking on detector performance and stability, among others.

We introduce MKIDGen3, a scalable and cost-efficient RFSoC-based readout system for UVOIR-sensitive Microwave Kinetic Inductance Detectors (MKIDs). MKIDGen3 not only doubles readout bandwidth, but also reduces power consumption and costs by 80% and 50%, respectively. The system features a central control node which facilitates array-level setup, data storage, image synthesis, and UI server functionality connected to a cluster of of low-cost RFSoC boards, each responsible for a 2 kilopixel sub-array. This open-source platform is tailored for smaller research groups lacking dedicated FPGA staff, offering ease of maintenance and adaptability. A notable innovation in MKIDGen3 is its system-level performance simulator, designed to eliminate guesswork in the development of optical MKID readouts and facilitating informed decision-making for DSP and device setup algorithms, a significant advancement. We discuss the development and demonstrated performance of the readout and simulator, highlighting their application to detectors in the laboratory and on sky.

Microchannel plate (MCP) detectors have been used on many ultraviolet (UV) space based observatories. Future NASA missions would benefit from scaled designs with larger areas, higher spatial resolution, and high counting rate capability. These prospects are being successfully demonstrated with cross strip (XS) anode readouts, but the electronics that read out such detectors would require reduction in size, weight, and power. The GRAPH ASIC was developed as an efficient high bandwidth solution to read out cross strip anodes for MCP detectors. First generation GRAPH ASICs have been wire bonded to circuit boards and initial testing and characterization have been done. Firmware and software have been implemented to process XS anode events producing X-Y photon positions. To further test and characterize performance of the GRAPH ASIC a GRAPH board is being used to read out photon events from an MCP detector with a cross strip anode. We present preliminary results on GRAPH design and operation. In addition we demonstrate photon detection with position and pulse height analysis and a description of the firmware currently being used to carry out these tests.

The most common instrument used by the exoplanet/brown dwarf direct imaging community at the W.M. Keck Observatory is currently the NIRC2 near-infrared imager. We document three on-sky testing results of non-uniform effects that exist in the NIRC2 system when operating in L and M-band that can affect the performance when conducting high-contrast imaging observations. First, we report the measurements of the throughput of the vector vortex L/M coronagraph. We quantify the throughput and additional background flux penalties, noting the effects of using the VVC in M-band are greater than in L-band. Second, we utilize the recently commissioned NIRC2 electronics upgrade to measure the L/M band sky variability at sub-second speeds. We find that the background varies at timescales of less than 30s, indicating that the electronics upgrade may improve opportunities for future surveys. Third, we document the contribution of the image derotator to the spatial non-uniformity in the background flux. We conclude by giving a set of how the Keck-NIRC2 high-contrast imaging community can adapt their observing strategies to improve the sensitivity of future surveys.