Salton Sea, California

The Salton Sea, California\u27s largest lake, is located in the southeastern desert region of California. It lies within a 7851 square mile endorheic hydrologic basin that includes the Coachella and Imperial Valleys of California, and the Mexicali Valley of Mexico, with a surface elevation of 227 feet below mean sea level (msl). The shallow nature of this hypersaline lake, with a surface area of 367 square miles (951 square kilometers) and a maximum depth of 51 feet (15.5 meters), renders it very sensitive to even slight changes of inflow volume. Over 85 percent of the water entering the Salton Sea results from agricultural run-off, 1.34 million acre feet (Maf), with less than three percent of annual inflow deriving from basin precipitation. The Salton Sea is situated in the Colorado Desert in one of the most arid regions of the United States. Annual precipitation is less than 3 in. (7.6 cm), and mean monthly temperatures in July are 92°F (33.3°C), with maximum temperatures exceeding 100°F (37.7°C) on more than 110 days per annum. Potential evaporation is estimated at 5.78 feet (1.76 meters) per year.https://inspire.redlands.edu/oh_chapters/1161/thumbnail.jp

Characterization of a multimode coplanar waveguide parametric amplifier

We characterize a novel Josephson parametric amplifier based on a flux-tunable quarter-wavelength resonator. The fundamental resonance frequency is ~1GHz, but we use higher modes of the resonator for our measurements. An on-chip tuning line allows for magnetic flux pumping of the amplifier. We investigate and compare degenerate parametric amplification, involving a single mode, and nondegenerate parametric amplification, using a pair of modes. We show that we reach quantum-limited noise performance in both cases, and we show that the added noise can be less than 0.5 added photons in the case of low gain

The pumpistor: a linearized model of a flux-pumped SQUID for use as a negative-resistance parametric amplifier

We describe a circuit model for a flux-driven SQUID. This is useful for developing insight into how these devices perform as active elements in parametric amplifiers. The key concept is that frequency mixing in a flux-pumped SQUID allows for the appearance of an effective negative resistance. In the three-wave, degenerate case treated here, a negative resistance appears only over a certain range of allowed input signal phase. This model readily lends itself to testable predictions of more complicated circuits.Comment: 4 pages, 3 figure

Characterization of LEO Satellites With All-Sky Photometric Signatures

We present novel techniques and methodology for unresolved photometric characterization of low-Earth Orbit (LEO) satellites. With the Pomenis LEO Satellite Photometric Survey our team has made over 14,000 observations of Starlink and OneWeb satellites to measure their apparent brightness. From the apparent brightness of each satellite, we calculate a new metric: the effective albedo, which quantifies the specularity of the reflecting satellite. Unlike stellar magnitude units, the effective albedo accounts for apparent range and phase angle and enables direct comparison of different satellites. Mapping the effective albedo from multiple observations across the sky produces an all-sky photometric signature which is distinct for each population of satellites, including the various sub-models of Starlink satellites. Space Situational Awareness (SSA) practitioners can use all-sky photometric signatures to differentiate populations of satellites, compare their reflection characteristics, identify unknown satellites, and find anomalous members. To test the efficacy of all-sky signatures for satellite identification, we applied a machine learning classifier algorithm which correctly identified the majority of satellites based solely on the effective albedo metric and with as few as one observation per individual satellite. Our new method of LEO satellite photometric characterization requires no prior knowledge of the satellite's properties and is readily scalable to large numbers of satellites such as those expected with developing communications mega-constellations.Comment: 11 pages, 8 figures, Proceedings of the 2022 AMOS Conferenc

Cryogenic micro-calorimeters for mass spectrometric identification of neutral molecules and molecular fragments

We have systematically investigated the energy resolution of a magnetic micro-calorimeter (MMC) for atomic and molecular projectiles at impact energies ranging from $E\approx13$ to 150 keV. For atoms we obtained absolute energy resolutions down to $\Delta E \approx 120$ eV and relative energy resolutions down to $\Delta E/E\approx10^{-3}$. We also studied in detail the MMC energy-response function to molecular projectiles of up to mass 56 u. We have demonstrated the capability of identifying neutral fragmentation products of these molecules by calorimetric mass spectrometry. We have modeled the MMC energy-response function for molecular projectiles and conclude that backscattering is the dominant source of the energy spread at the impact energies investigated. We have successfully demonstrated the use of a detector absorber coating to suppress such spreads. We briefly outline the use of MMC detectors in experiments on gas-phase collision reactions with neutral products. Our findings are of general interest for mass spectrometric techniques, particularly for those desiring to make neutral-particle mass measurements

Eutrophication

Eutrophication is a syndrome of [../152248/index.html ecosystem]] responses to human activities that fertilize water bodies with nitrogen (N) and phosphorus (P), often leading to changes in animal and plant populations and degradation of water and habitat quality. Nitrogen and phosphorus are essential components of structural proteins, enzymes, cell membranes, nucleic acids, and molecules that capture and utilize light and chemical energy to support life. The biologically available forms of N and P are present at low concentrations in pristine lakes, rivers, estuaries, and in vast regions of the upper ocean.https://inspire.redlands.edu/oh_chapters/1160/thumbnail.jp

Single-shot Readout of a Superconducting Qubit using a Josephson Parametric Oscillator

We propose and demonstrate a new read-out technique for a superconducting qubit by dispersively coupling it to a Josephson parametric oscillator. We employ a tunable quarter-wavelength superconducting resonator and modulate its resonant frequency at twice its value with an amplitude surpassing the threshold for parametric instability. We map the qubit states onto two distinct states of classical parametric oscillation: one oscillating state, with $185\pm15$ photons in the resonator, and one with zero oscillation amplitude. This high contrast obviates a following quantum-limited amplifier. We demonstrate proof-of-principle, single-shot readout performance, and present an error budget indicating that this method can surpass the fidelity threshold required for quantum computing.Comment: 11 pages, 5 figure

Absolute rate coefficients for photorecombination of berylliumlike and boronlike silicon ions

We report measured rate coefficients for electron-ion recombination for Si10+ forming Si9+ and for Si9+ forming Si8+, respectively. The measurements were performed using the electron-ion merged-beams technique at a heavy-ion storage ring. Electron-ion collision energies ranged from 0 to 50 eV for Si9+ and from 0 to 2000 eV for Si10+, thus, extending previous measurements for Si10+ [Orban et al. 2010, Astrophys. J. 721, 1603] to much higher energies. Experimentally derived rate coefficients for the recombination of Si9+ and Si10+ ions in a plasma are presented along with simple parameterizations. These rate coefficients are useful for the modeling of the charge balance of silicon in photoionized plasmas (Si9+ and Si10+) and in collisionally ionized plasmas (Si10+ only). In the corresponding temperature ranges, the experimentally derived rate coefficients agree with the latest corresponding theoretical results within the experimental uncertainties.Comment: 17 pages, 7 figures, 3 tables, 66 references, submitted to the J. Phys. B special issue on atomic and molecular data for astrophysicist