Search

Single-photon detectors based on the superconducting transition-edge sensor (TES) are used in a number of visible to near-infrared (VNIR) applications, particularly for photon-number-resolving measurements in quantum information science. To be practical for large-scale photonic quantum computing or for future spectroscopic imaging applications in astronomy, the size of VNIR TES arrays must be increased from a few pixels to many thousands. Historically, TES arrays have been read out with multiplexed superconducting quantum interference devices (SQUIDs), but the microsecond-duration pulse signals of VNIR TESs are notoriously difficult to multiplex. In this manuscript, we introduce the kinetic inductance current sensor (KICS), a more readily scalable readout technology that exploits the nonlinear kinetic inductance in a superconducting resonator to make sensitive current measurements. KICS devices can replace SQUIDs for many applications because of their ability to measure fast, high slew-rate signals, their compatibility with standard microwave frequency-division multiplexing techniques, and their relatively simple fabrication. Here, we demonstrate the readout of a VNIR TES using a KICS with $3.7$ $\text{MHz}$ of bandwidth. We measure a readout noise of $1.4$ $\text{pA}/\sqrt{\text{Hz}}$, considerably below the TES noise at frequencies of interest, and a TES energy resolution of $(0.137 \pm 0.001)$ $\text{eV}$ at $0.8$ $\text{eV}$, comparable to resolutions observed with non-multiplexed SQUID readouts., Comment: 14 pages, 8 figures

Naturally occurring background radiation is a source of correlated decoherence events in superconducting qubits that will challenge error-correction schemes. To characterize the radiation environment in an unshielded laboratory, we performed broadband, spectroscopic measurements of background events in silicon substrates located inside a millikelvin refrigerator, an environment representative of superconducting qubit systems. We measured the background spectra in silicon substrates of two thicknesses, 0.5 mm and 1.5 mm, and obtained the average event rate and the integrated power deposition. In a 25 mm^2 area and the thinner substrate, these values are 0.023 events per second and 4.9 keV/s, counting events that deposit at least 40 keV. We find the background spectrum to be nearly featureless. Its intensity decreases by a factor of 40,000 between 100 keV and 3 MeV for silicon substrates 0.5 mm thick. We find the cryogenic measurements to be in good agreement with predictions based on measurements of the terrestrial gamma-ray flux, published models of cosmic-ray fluxes, a crude model of the cryostat, and radiation-transport simulations. No free parameters are required to predict the background spectra in the silicon substrates. The good agreement between measurements and predictions allow assessment of the relative contributions of terrestrial and cosmic background sources and their dependence on substrate thickness. Our spectroscopic measurements are performed with superconducting microresonators that transduce deposited energy to a readily detectable electrical signal. We find that gamma-ray emissions from radioisotopes are responsible for the majority of events depositing E<1.5 MeV, while nucleons among the cosmic-ray secondary particles cause most events that deposit more energy. These results suggest several paths to reducing the impact of background radiation on quantum circuits.

Superconducting detectors are a promising technology for probing dark matter at extremely low masses, where dark matter interactions are currently unconstrained. Realizing the potential of such detectors requires new readout technologies to achieve the lowest possible thresholds for deposited energy. Here we perform a prototype search for dark matter--electron interactions with kinetic inductance detectors (KIDs), a class of superconducting detector originally designed for infrared astronomy applications. We demonstrate that existing KIDs can achieve effective thresholds as low as 0.2 eV, and we use existing data to set new dark matter constraints. The relative maturity of the technology underlying KIDs means that this platform can be scaled significantly with existing tools, enabling powerful new searches in the coming years., Comment: 6+6 pages, 4+3 figures

In preparation for the 2023 NSAC Long Range Plan (LRP), members of the Nuclear Science community gathered to discuss the current state of, and plans for further leveraging opportunities in, QIST in NP research at the Quantum Information Science for U.S. Nuclear Physics Long Range Planning workshop, held in Santa Fe, New Mexico on January 31 - February 1, 2023. The workshop included 45 in-person participants and 53 remote attendees. The outcome of the workshop identified strategic plans and requirements for the next 5-10 years to advance quantum sensing and quantum simulations within NP, and to develop a diverse quantum-ready workforce. The plans include resolutions endorsed by the participants to address the compelling scientific opportunities at the intersections of NP and QIST. These endorsements are aligned with similar affirmations by the LRP Computational Nuclear Physics and AI/ML Workshop, the Nuclear Structure, Reactions, and Astrophysics LRP Town Hall, and the Fundamental Symmetries, Neutrons, and Neutrinos LRP Town Hall communities., Comment: A white paper for the 2023 nuclear physics long-range planning activity, emerging from the workshop "Quantum Information Science for U.S. Nuclear Physics Long Range Planning'', held in Santa Fe, New Mexico on January 31 - February 1, 2023. 26 pages with 7 figures

We report on the 1,000-element transition-edge sensor (TES) x-ray spectrometer implementation of the TOMographic Circuit Analysis Tool (TOMCAT). TOMCAT combines a high spatial resolution scanning electron microscope (SEM) with a highly efficient and pixelated TES spectrometer to reconstruct three-dimensional maps of nanoscale integrated circuits (ICs). A 240-pixel prototype spectrometer was recently used to reconstruct ICs at the 130 nm technology node, but to increase imaging speed to more practical levels, the detector efficiency needs to be improved. For this reason, we are building a spectrometer that will eventually contain 3,000 TES microcalorimeters read out with microwave superconducting quantum interference device (SQUID) multiplexing, and we currently have commissioned a 1,000 TES subarray. This still represents a significant improvement from the 240-pixel system and allows us to begin characterizing the full spectrometer performance. Of the 992 maximimum available readout channels, we have yielded 818 devices, representing the largest number of TES x-ray microcalorimeters simultaneously read out to date. These microcalorimeters have been optimized for pulse speed rather than purely energy resolution, and we measure a FWHM energy resolution of 14 eV at the 8.0 keV Cu K$\alpha$ line., Comment: 5 pages, 4 figures, submitted to IEEE Transactions on Applied Superconductivity

X-ray nanotomography is a powerful tool for the characterization of nanoscale materials and structures, but is difficult to implement due to competing requirements on X-ray flux and spot size. Due to this constraint, state-of-the-art nanotomography is predominantly performed at large synchrotron facilities. We present a laboratory-scale nanotomography instrument that achieves nanoscale spatial resolution while changing the limitations of conventional tomography tools. The instrument combines the electron beam of a scanning electron microscope (SEM) with the precise, broadband X-ray detection of a superconducting transition-edge sensor (TES) microcalorimeter. The electron beam generates a highly focused X-ray spot in a metal target held micrometers away from the sample of interest, while the TES spectrometer isolates target photons with high signal-to-noise. This combination of a focused X-ray spot, energy-resolved X-ray detection, and unique system geometry enable nanoscale, element-specific X-ray imaging in a compact footprint. The proof-of-concept for this approach to X-ray nanotomography is demonstrated by imaging 160 nm features in three dimensions in 6 layers of a Cu-SiO2 integrated circuit, and a path towards finer resolution and enhanced imaging capabilities is discussed.

Feature sizes in integrated circuits have decreased substantially over time, and it has become increasingly difficult to three-dimensionally image these complex circuits after fabrication. This can be important for process development, defect analysis, and detection of unexpected structures in externally sourced chips, among other applications. Here, we report on a non-destructive, tabletop approach that addresses this imaging problem through x-ray tomography, which we uniquely realize with an instrument that combines a scanning electron microscope (SEM) with a transition-edge sensor (TES) x-ray spectrometer. Our approach uses the highly focused SEM electron beam to generate a small x-ray generation region in a carefully designed target layer that is placed over the sample being tested. With the high collection efficiency and resolving power of a TES spectrometer, we can isolate x-rays generated in the target from background and trace their paths through regions of interest in the sample layers, providing information about the various materials along the x-ray paths through their attenuation functions. We have recently demonstrated our approach using a 240 Mo/Cu bilayer TES prototype instrument on a simplified test sample containing features with sizes of $\sim$1 $\mu$m. Currently, we are designing and building a 3000 Mo/Au bilayer TES spectrometer upgrade, which is expected to improve the imaging speed by factor of up to 60 through a combination of increased detector number and detector speed., Comment: 5 pages, 3 figures, published in IEEE Transactions on Applied Superconductivity

Understanding the nature of charge density waves (CDW) in cuprate superconductors has been complicated by material specific differences. A striking example is the opposite doping dependence of the CDW ordering wavevector in La-based and Y-based compounds, the two families where charge ordering is strongest and best characterized. Here we report a combined resonant soft X-ray scattering (RSXS) and neutron scattering study of charge and spin density waves in isotopically enriched La$_{1.8-x}$ Eu$_{0.2}$ Sr$_{x}$ CuO$_{4}$ over a range of doping $0.07 \leq x \leq 0.20$. For all dopings studied by RSXS, we find that the CDW amplitude is approximately temperature-independent and develops well above experimentally accessible temperatures. Surprisingly, the CDW ordering wavevector shows a non-monotonic temperature dependence, with a sudden change occurring at temperatures near the SDW onset temperature. We describe this behavior with a Landau-Ginzburg theory for an incommensurate CDW in a metallic system with a finite charge compressibility and CDW-SDW coupling. Our Landau-Ginzburg analysis suggests that the ordering wavevector at high temperatures decreases with increased doping. This behavior is opposite to the trend at low temperatures and highly reminiscent of the doping dependence seen in YBa$_2$ Cu$_3$ O$_{6+\delta}$ , suggesting a common origin of the CDW in hole-doped cuprate superconductors., Comment: Manuscript submitted to PNAS; ArXiv version formatted in Revtex4-2; Supplementary Material included as appendices; 20 pages, 14 figures (6 in the main text), and 41 references

We report the direct imaging discovery of a low-mass companion to the nearby accelerating A star, HIP 109427, with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument coupled with the MKID Exoplanet Camera (MEC) and CHARIS integral field spectrograph. CHARIS data reduced with reference star PSF subtraction yield 1.1-2.4 $\mu$m spectra. MEC reveals the companion in $Y$ and $J$ band at a comparable signal-to-noise ratio using stochastic speckle discrimination, with no PSF subtraction techniques. Combined with complementary follow-up $L_{\rm p}$ photometry from Keck/NIRC2, the SCExAO data favors a spectral type, effective temperature, and luminosity of M4-M5.5, 3000-3200 $K$, and $\log_{10}(L/L_{\rm \odot}) = -2.28^{+0.04}_{-0.04}$, respectively. Relative astrometry of HIP 109427 B from SCExAO/CHARIS and Keck/NIRC2, and complementary Gaia-Hipparcos absolute astrometry of the primary favor a semimajor axis of $6.55^{+3.0}_{-0.48}$ au, an eccentricity of $0.54^{+0.28}_{-0.15}$, an inclination of $66.7^{+8.5}_{-14}$ degrees, and a dynamical mass of $0.280^{+0.18}_{-0.059}$ $M_{\odot}$. This work shows the potential for extreme AO systems to utilize speckle statistics in addition to widely-used post-processing methods to directly image faint companions to nearby stars near the telescope diffraction limit., Comment: 13 pages, 7 figures, 3 tables

We present the MKID Exoplanet Camera (MEC), a z through J band (800 - 1400 nm) integral field spectrograph located behind The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) at the Subaru Telescope on Maunakea that utilizes Microwave Kinetic Inductance Detectors (MKIDs) as the enabling technology for high contrast imaging. MEC is the first permanently deployed near-infrared MKID instrument and is designed to operate both as an IFU, and as a focal plane wavefront sensor in a multi-kHz feedback loop with SCExAO. The read noise free, fast time domain information attainable by MKIDs allows for the direct probing of fast speckle fluctuations that currently limit the performance of most high contrast imaging systems on the ground and will help MEC achieve its ultimate goal of reaching contrasts of $10^{-7}$ at 2$\lambda / D$. Here we outline the instrument details of MEC including the hardware, firmware, and data reduction and analysis pipeline. We then discuss MEC's current on-sky performance and end with future upgrades and plans., Comment: To be published in Publications of the Astronomical Society of the Pacific

We report on the design, commissioning, and initial measurements of a Transition-edge Sensor (TES) x-ray spectrometer for the Electron Beam Ion Trap (EBIT) at the National Institute of Standards and Technology (NIST). Over the past few decades, the NIST EBIT has produced numerous studies of highly charged ions in diverse fields such as atomic physics, plasma spectroscopy, and laboratory astrophysics. The newly commissioned NIST EBIT TES Spectrometer (NETS) improves the measurement capabilities of the EBIT through a combination of high x-ray collection efficiency and resolving power. NETS utilizes 192 individual TES x-ray microcalorimeters (166/192 yield) to improve upon the collection area by a factor of ~30 over the 4-pixel neutron transmutation doped germanium-based microcalorimeter spectrometer previously used at the NIST EBIT. The NETS microcalorimeters are optimized for the x-ray energies from roughly 500 eV to 8,000 eV and achieve an energy resolution of 3.7 eV to 5.0 eV over this range, a more modest (<2X) improvement over the previous microcalorimeters. Beyond this energy range NETS can operate with various trade-offs, the most significant of which are reduced efficiency at lower energies and being limited to a subset of the pixels at higher energies. As an initial demonstration of the capabilities of NETS, we measured transitions in He-like and H-like O, Ne, and Ar as well as Ni-like W. We detail the energy calibration and data analysis techniques used to transform detector counts into x-ray spectra, a process that will be the basis for analyzing future data.

We use narrow spectral lines from the x-ray spectra of various highlycharged ions to measure low-energy tail-like deviations from a Gaussian responsefunction in a microcalorimter x-ray spectrometer with Au absorbers at energiesfrom 650 eV to 3320 eV. We review the literature on low energy tails in othermicrocalorimter x-ray spectrometers and present a model that explains all thereviewed tail fraction measurements. In this model a low energy tail arises fromthe combination of electron escape and energy trapping associated with Bi x-rayabsorbers.

The energy resolution of a single photon counting Microwave Kinetic Inductance Detector (MKID) can be degraded by noise coming from the primary low temperature amplifier in the detector's readout system. Until recently, quantum limited amplifiers have been incompatible with these detectors due to dynamic range, power, and bandwidth constraints. However, we show that a kinetic inductance based traveling wave parametric amplifier can be used for this application and reaches the quantum limit. The total system noise for this readout scheme was equal to ~2.1 in units of quanta. For incident photons in the 800 to 1300 nm range, the amplifier increased the average resolving power of the detector from ~6.7 to 9.3 at which point the resolution becomes limited by noise on the pulse height of the signal. Noise measurements suggest that a resolving power of up to 25 is possible if redesigned detectors can remove this additional noise source.

We present DARKNESS (the DARK-speckle Near-infrared Energy-resolving Superconducting Spectrophotometer), the first of several planned integral field spectrographs to use optical/near-infrared Microwave Kinetic Inductance Detectors (MKIDs) for high-contrast imaging. The photon counting and simultaneous low-resolution spectroscopy provided by MKIDs will enable real-time speckle control techniques and post-processing speckle suppression at framerates capable of resolving the atmospheric speckles that currently limit high-contrast imaging from the ground. DARKNESS is now operational behind the PALM-3000 extreme adaptive optics system and the Stellar Double Coronagraph at Palomar Observatory. Here we describe the motivation, design, and characterization of the instrument, early on-sky results, and future prospects., Comment: 17 pages, 17 figures. PASP Published

We have fabricated and characterized 10,000 and 20,440 pixel Microwave Kinetic Inductance Detector (MKID) arrays for the Dark-speckle Near-IR Energy-resolved Superconducting Spectrophotometer (DARKNESS) and the MKID Exoplanet Camera (MEC). These instruments are designed to sit behind adaptive optics systems with the goal of directly imaging exoplanets in a 800-1400 nm band. Previous large optical and near-IR MKID arrays were fabricated using substoichiometric titanium nitride (TiN) on a silicon substrate. These arrays, however, suffered from severe non-uniformities in the TiN critical temperature, causing resonances to shift away from their designed values and lowering usable detector yield. We have begun fabricating DARKNESS and MEC arrays using platinum silicide (PtSi) on sapphire instead of TiN. Not only do these arrays have much higher uniformity than the TiN arrays, resulting in higher pixel yields, they have demonstrated better spectral resolution than TiN MKIDs of similar design. PtSi MKIDs also do not display the hot pixel effects seen when illuminating TiN on silicon MKIDs with photons with wavelengths shorter than 1 um., Comment: 16 pages, 8 figures, published in Optics Express

We report on the development of Microwave Kinetic Inductance Detectors (MKIDs) using platinum silicide as the sensor material. MKIDs are an emerging superconducting detector technology, capable of measuring the arrival times of single photons to better than two microseconds and their energies to around ten percent. Previously, MKIDs have been fabricated using either sub-stoichiometric titanium nitride or aluminum, but TiN suffers from spatial inhomogeneities in the superconducting critical temperature and Al has a low kinetic inductance fraction, causing low detector sensitivity. To address these issues, we have instead fabricated PtSi microresonators with superconducting critical temperatures of 944$\pm$12~mK and high internal quality factors ($Q_i \gtrsim 10^6$). These devices show typical quasiparticle lifetimes of $\tau_{qp} \approx 30$--$40~\mu$s and spectral resolution, $R = \lambda / \Delta \lambda$, of 8 at 406.6~nm. We compare PtSi MKIDs to those fabricated with TiN and detail the substantial advantages that PtSi MKIDs have to offer., Comment: 5 pages, 5 figures, accepted by APL

We report on a search for optical pulsations from PSR J0337+1715 at its observed radio pulse period. PSR J0337+1715 is a millisecond pulsar (2.7 ms spin period) in a triple hierarchical system with two white dwarfs, and has a known optical counterpart with g-band magnitude 18. The observations were done with the Array Camera for Optical to Near-IR Spectrophotometry (ARCONS) at the 200" Hale telescope at Palomar Observatory. No significant pulsations were found in the range 4000-11000 angstroms, and we can limit pulsed emission in g-band to be fainter than 25 mag., Comment: 4 pages, 2 figures, accepted to MNRAS

The Array Camera for Optical to Near-IR Spectrophotometry, or ARCONS, is a camera based on Microwave Kinetic Inductance Detectors (MKIDs), a new technology that has the potential for broad application in astronomy. Using an array of MKIDs, the instrument is able to produce time-resolved imaging and low-resolution spectroscopy constructed from detections of individual photons. The arrival time and energy of each photon are recorded in a manner similar to X-ray calorimetry, but at higher photon fluxes. The technique works over a very large wavelength range, is free from fundamental read noise and dark-current limitations, and provides microsecond-level timing resolution. Since the instrument reads out all pixels continuously while exposing, there is no loss of active exposure time to readout. The technology requires a different approach to data reduction compared to conventional CCDs. We outline here the prototype data reduction pipeline developed for ARCONS, though many of the principles are also more broadly applicable to energy-resolved photon counting arrays (e.g., transition edge sensors, superconducting tunnel junctions). We describe the pipeline's current status, and the algorithms and techniques employed in taking data from the arrival of photons at the MKID array to the production of images, spectra, and time-resolved light curves., Comment: 16 pages, 19 figures, pdflatex, accepted for ApJS

For X-ray imaging spectroscopy, high spatial resolution over a large field of view is often as important as high energy resolution, but current X-ray detectors do not provide both in the same device. Thermal Kinetic Inductance Detectors (TKIDs) are being developed as they offer a feasible way to combine the energy resolution of transition edge sensors with pixel counts approaching CCDs and thus promise significant improvements for many X-ray spectroscopy applications. TKIDs are a variation of Microwave Kinetic Inductance Detectors (MKIDs) and share their multiplexibility: working MKID arrays with 2024 pixels have recently been demonstrated and much bigger arrays are under development. In this work, we present our first working TKID prototypes which are able to achieve an energy resolution of 75 eV at 5.9 keV, even though their general design still has to be optimized. We further describe TKID fabrication, characterization, multiplexing and working principle and demonstrate the necessity of a data fitting algorithm in order to extract photon energies. With further design optimizations we expect to be able to improve our TKID energy resolution to less than 10 eV at 5.9 keV., Comment: 7 pages, 4 figures, accepted for publication in Applied Physics Letters

The Keck science community is entering an era of unprecedented change. Powerful new instrument like ZTF, JWST, LSST, and the ELTs will catalyze this change, and we must be ready to take full advantage to maintain our position of scientific leadership. The best way to do this is to continue the UC and Caltech tradition of technical excellence in instrumentation. In this whitepaper we describe a new instrument called KRAKENS to help meet these challenges. KRAKENS uses a unique detector technology (MKIDs) to enable groundbreaking science across a wide range of astrophysical research topics. This document will lay out the detailed expected science return of KRAKENS., Comment: 19 pages, 17 figures

We have fabricated 2024 pixel microwave kinetic inductance detector (MKID) arrays in the ultraviolet/optical/near-IR (UVOIR) regime that are currently in use in astronomical instruments. In order to make MKIDs desirable for novel instruments, larger arrays with nearly perfect yield need to be fabricated. As array size increases, however, the percent yield often decreases due to frequency collisions in the readout. The per-pixel performance must also be improved, namely the energy resolution. We are investigating ways to reduce frequency collisions and to improve the per pixel performance of our devices through new superconducting material systems and fabrication techniques. There are two main routes that we are currently exploring. First, we are attempting to create more uniform titanium nitride films through the use of atomic layer deposition rather than the more traditional sputtering method. In addition, we are experimenting with completely new material systems for MKIDs, such as platinum silicide., Comment: 4 pages, 2 figures, accepted for publication in IEEE Transactions on Applied Superconductivity

AM Canum Venaticorum (AM CVn) stars belong to a class of ultra-compact, short period binaries with spectra dominated largely by helium. SDSS J0926+3624 is of particular interest as it is the first observed eclipsing AM CVn system. We observed SDSS J0926+3624 with the \textbf{Ar}ray \textbf{C}amera for \textbf{O}ptical to \textbf{N}ear-IR \textbf{S}pectrophotometry (ARCONS) at the Palomar 200" telescope. ARCONS uses a relatively new type of energy-resolved photon counters called Microwave Kinetic Inductance Detectors (MKIDs). ARCONS, sensitive to radiation from 350 to 1100 nm, has a time resolution of several microseconds and can measure the energy of a photon to $\sim10%$. We present the light curves for these observations and examine changes in orbital period from prior observations. Using a quadratic ephemeris model, we measure a period rate of change $\dot{P} = (3.07 \pm 0.56)\times 10^{-13}$. In addition, we use the high timing resolution of ARCONS to examine the system's high frequency variations and search for possible quasi-periodic oscillations (QPOs). Finally, we use the instrument's spectral resolution to examine the light curves in various wavelength bands. We do not find any high frequency QPOs or significant spectral variability throughout an eclipse., Comment: 8 pages, 7 figures, submitted to MNRAS

We observe an extraordinary link in the Crab pulsar between the enhancement of an optical pulse and the timing of the corresponding giant radio pulse. At optical through infrared wavelengths, our observations use the high time resolution of ARCONS, a unique superconducting energy-resolving photon-counting array at the Palomar 200-inch telescope. At radio wavelengths, we observe with the Robert C. Byrd Green Bank Telescope and the GUPPI backend. We see an $11.3\pm2.5\%$ increase in peak optical flux for pulses that have an accompanying giant radio pulse arriving near the peak of the optical main pulse, in contrast to a $3.2\pm0.5\%$ increase when an accompanying giant radio pulse arrives soon after the optical peak. We also observe that the peak of the optical main pulse is $2.8\pm0.8\%$ enhanced when there is a giant radio pulse accompanying the optical interpulse. We observe no statistically significant spectral differences between optical pulses accompanied by and not accompanied by giant radio pulses. Our results extend previous observations of optical-radio correlation to the time and spectral domains. Our refined temporal correlation suggests that optical and radio emission are indeed causally linked, and the lack of spectral differences suggests that the same mechanism is responsible for all optical emission., Comment: 5 pages, 5 figures. Updated to match revised version, accepted to ApJL Nov 7, 2013. Several additions and improved DM in timing solution

We present the design, construction, and commissioning results of ARCONS, the Array Camera for Optical to Near-IR Spectrophotometry. ARCONS is the first ground-based instrument in the optical through near-IR wavelength range based on Microwave Kinetic Inductance Detectors (MKIDs). MKIDs are revolutionary cryogenic detectors, capable of detecting single photons and measuring their energy without filters or gratings, similar to an X-ray microcalorimeter. MKIDs are nearly ideal, noiseless photon detectors, as they do not suffer from read noise or dark current and have nearly perfect cosmic ray rejection. ARCONS is an Integral Field Spectrograph (IFS) containing a lens-coupled 2024 pixel MKID array yielding a 20"x20" field of view, and has been deployed on the Palomar 200" and Lick 120" telescopes for 24 nights of observing. We present initial results showing that ARCONS and its MKID arrays are now a fully operational and powerful tool for astronomical observations., Comment: 12 pages, 16 figures, submitted to PASP