Upcoming planetary missions and the applicability of high temperature superconductor bolometers

Planetary missions to Mars and beyond can last 11 years and longer, making impractical the use of stored cryogens. Passive radiative coolers and single-stage mechanical coolers remain possibilities. CRAF and CASSINI, both using the newly developed Mariner Mark 2 spacecraft, will be the next outer planet missions after Galileo; they are intended to provide information on the origin and evolution of the solar system. CRAF is a cometary rendezvous mission slated for a 1994 launch. CASSINI has been chosen by ESA and will be launched by a Titan 4/Centaur in 1996. It will fly by Jupiter in 2000, inject an ESA-supplied probe into Titan in 2002, and take data in Saturn orbit from 2002 to 2006. NASA/Goddard is currently developing a prototype Fourier transform spectrometer (CIRS) that will be proposed for the CASSINI mission. The baseline infrared detectors for CIRS are HgCdTe to 16 microns and Schwarz-type thermopiles from 16 to 1000 microns. The far infrared focal plane could be switched from thermopiles to high temperature superconductor (HTS) bolometers between now and 1996. An HTS bolometer could be built using the kinetic inductance effect, or the sharp resistance change at the transition. The transition-edge bolometer is more straightforward to implement and initial efforts at NASA/Goddard are directed to that device. A working device was made and tested in early 1989. It also has somewhat elevated noise levels below 100 Hz. Upcoming efforts will center on reducing the time constant of the HTS bolometer by attempting to deposit an HTS film on a diamond substrate, and by thinning SrTiO3 substrates. Attempts will be made to improve the film quality to reduce th 1/f noise level, and to improve the thermal isolation to increase the bolometer sensitivity. An attempt is being made to deposit good-quality HTS films on diamond films using an MOCVD technique

Mars: Mariner 9 spectroscopic evidence for H2O ice clouds

Spectral features observed with the Mariner 9 Interferometer Spectrometer are identified as those of water ice. Measured spectra are compared with theoretical calulations for the transfer of radiation through clouds of ice particles with variations in size distribution and integrated cloud mass. Comparisons with an observed spectrum from the Tharsis Ridge region indicate water ice clouds composed of particles with mean radius 2.0 microns and integrated cloud mass 0.00005 g/sq cm

Thermal emission spectroscopy of the middle atmosphere

The general objective of this research is to obtain, via remote sensing, simultaneous measurements of the vertical distributions of stratospheric temperature, ozone, and trace constituents that participate in the catalytic destruction of ozone (NO(sub y): NO, NO2, NO3, HNO3, ClONO2, N2O5, HNO4; Cl(sub x): HOCl), and the source gases for the catalytic cycles (H2O, CH4, N2O, CF2Cl2, CFCl3, CCl4, CH3Cl, CHF2Cl, etc.). Data are collected during a complete diurnal cycle in order to test our present understanding of ozone chemistry and its associate catalytic cycles. The instrumentation employed is an emission-mode, balloon-borne, liquid-nitrogen-cooled Michelson interferometer-spectrometer (SIRIS), covering the mid-infrared range with a spectral resolution of 0.020 cm(exp -1). Cryogenic cooling combined with the use of extrinsic silicon photoconductor detectors allows the detection of weak emission features of stratospheric gaseous species. Vertical distributions of these species are inferred from scans of the thermal emission of the limb in a sequence of elevation angles. The fourth SIRIS balloon flight was carried out from Palestine, Texas on September 15-16, 1986 with 9 hours of nighttime data (40 km). High quality data with spectral resolution 0.022 cm(exp -1), were obtained for numerous limb sequences. Fifteen stratospheric species have been identified to date from this flight: five species from the NO(sub y) family (HNO3, NO2, NO, ClONO2, N2O5), plus CO2, O3, H2O, N2O, CH4, CCl3F, CCl2F2, CHF2Cl, CF4, and CCl4. The nighttime values of N2O5, ClONO2, and total odd nitrogen have been measured for the first time, and compared to model results. Analysis of the diurnal variation of N2O5 within the 1984 and 1986 data sets, and of the 1984 ClONO2 measurements, were presented in the literature. The demonstrated ability of SIRIS to measure all the major NO(sub y) species, and therefore to determine the partitioning of the nitrogen family over a continuous diurnal cycle, is a powerful tool in the verification and improvement of photochemical modeling

Master\u27s Recital: Marvin J. Carlton, Oboe; Jamie Hinkel, Piano; Gregory Kunde, Tenor; April 30, 1977

Centennial East Recital HallSaturday EveningApril 30, 19778:30 p.m

Probing the Quark-Gluon Plasma at the LHC with Z0^{0}- tagged Jets in CMS

An important tool in quark-gluon plasma studies at RHIC has been the measurement of dijets investigated via leading hadron correlations. With much higher rates for hard processes at the Large Hadron Collider, studies of Z^0tagged jets become possible. A clear experimental signature is provided by the measurement of muon pairs from the Z^0 decays, for which CMS is an ideally suited detector. Instead of measuring back-to-back correlations of two strongly interacting particles, one side is replaced by an electromagnetic probe which propagates through the plasma undisturbed and provides a measurement of the energy of the initial hard scattering. We propose to use lepton-pair tagged jets to study medium-induced partonic energy loss and to measure in-medium parton fragmentation functions. The lepton pairs from semileptonic decays of heavy meson pairs (B overline {B} and D overline{D}) are a background source for the dilepton jet tag signal. We present the calculated signal rates (using PYTHIA) and background rates (using HVQMNR). We also discuss strategies for maximizing the signal-to-background ratio

The infrared interferometer spectrometer experiment for the Mars Mariner 1971 orbital mission

Infrared interferometer spectrometer for Mariner spacecraft in Mars orbi

Incorporating Radial Flow in the Lattice Gas Model for Nuclear Disassembly

We consider extensions of the lattice gas model to incorporate radial flow. Experimental data are used to set the magnitude of radial flow. This flow is then included in the Lattice Gas Model in a microcanonical formalism. For magnitudes of flow seen in experiments, the main effect of the flow on observables is a shift along the $E^*/A$ axis.Comment: Version accepted for publication in Phys. Rev. C, Rapid Communicatio

Beable trajectories for revealing quantum control mechanisms

The dynamics induced while controlling quantum systems by optimally shaped laser pulses have often been difficult to understand in detail. A method is presented for quantifying the importance of specific sequences of quantum transitions involved in the control process. The method is based on a ``beable'' formulation of quantum mechanics due to John Bell that rigorously maps the quantum evolution onto an ensemble of stochastic trajectories over a classical state space. Detailed mechanism identification is illustrated with a model 7-level system. A general procedure is presented to extract mechanism information directly from closed-loop control experiments. Application to simulated experimental data for the model system proves robust with up to 25% noise.Comment: Latex, 20 pages, 13 figure