Antarctic Mapping Mission Planning Aids

On November 4, 1995, the Canadian RADARSAT was carried aloft by a NASA rocket launched from Vandenburg Air Force Base. Radarsat is equipped with a C-band Synthetic Aperture Radar (SAR) capable of acquiring high resolution (25 m) images of Earth's surface day or night and under all weather conditions. Along with the attributes familiar to researchers working with SAR data from the European Space Agency's Earth Remote Sensing Satellite and the Japanese Earth Resources Satellite, RADARSAT will have enhanced flexibility to collect data using a variety of swath widths, incidence angles and resolutions. Most importantly, for scientists interested in Antarctica, the agreement for a U.S. launch of RADARSAT includes a provision for rotating in orbit the normally right-looking SAR to a left-looking mode. This 'Antarctic Mode' will provide for the first time a nearly instantaneous, high resolution view of the entirety of Antarctica on each of two proposed mappings separated by 2 years. This is an unprecedented opportunity to finish mapping one of the few remaining uncharted regions of the Earth. The completed maps will also provide two important benchmarks for gauging changes of Antarctica's ice cover. The preparation of a digital mosaic of Antarctica is being conducted under a NASA Pathfinder Project awarded to the Byrd Polar Research Center of The Ohio State University. The primary goal of this proposal is to compile digital SAR mosaics of the entire Antarctic continent using a combination of standard and extended beams during the "Antarctic Mode" of the Radarsat Mission. Agreements with the Canadian Space Agency call for the first Antarctic Mapping Manuever to occur in September, 1997. A mission plan to coordinate that complex acquisition and downlinking of Antarctic data has been developed by NASA's Jet Propulsion Laboratory. The Alaska SAR Facility (ASF) will be used as the primary data collection site supported by collections at the Canadian Gatineau and Prince Albert Ground Stations. ASF will process data into images which will be sent to OSU for compositing into map products using state-of-the-art equipment to be designed by Vexcel Corporation of Boulder Colorado. Imaging geometry will be constrained over the Antarctic using active radar transponders constructed by the Environmental Research Institute of Michigan and by corner reflectors deployed by the British Antarctic Survey. Additional ground control is being supplied by the National Imagery and Mapping Agency. Final products will be distributed through the ASF and the National Snow and Ice Data Center which are both NASA Data Archive Centers. The mosaics and ancillary information will be prepared on CDROM and will be made available to the science community through NASA DAACs. Science opportunities envisioned for the program are summarized on the accompanying table. These include studying the dynamics and variability of the Antarctic Ice Sheet including studies of regions like the Wordie Ice Shelf and the Larsen Ice Shelf which have recently experienced unexplained and nearly catastropic retreat. Geologic applications include large scale mapping of faults, volcanic features, and mountain building processes (particularly the Transantarctic Mountains). Finally, there is simply the unprecedented opportunity to use these digital maps in studies of many previously unexplored areas of the Southern Continent.NASACanadian Space Agenc

Search for a light pseudoscalar Higgs boson in the boosted mu mu tau tau final state in proton-proton collisions at root s=13 TeV

A search for a light pseudoscalar Higgs boson (a) decaying from the 125 GeV (or a heavier) scalar Higgs boson (H) is performed using the 2016 LHC proton-proton collision data at root s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), collected by the CMS experiment. The analysis considers gluon fusion and vector boson fusion production of the H, followed by the decay H -> aa -> mu mu tau tau, and considers pseudoscalar masses in the range 3.6 aa -> mu mu tau tau, down to 1.5 (2.0)x10(-4) for m(H) = 125 (300) GeV. Model-dependent limits on B(H -> aa) are set within the context of two Higgs doublets plus singlet models, with the most stringent results obtained for Type-III models. These results extend current LHC searches for heavier a bosons that decay to resolved lepton pairs and provide the first such bounds for an H boson with a mass above 125 GeV.Peer reviewe

Azimuthal separation in nearly back-to-back jet topologies in inclusive 2-and 3-jet events in pp collisions at root s=13TeV

A measurement for inclusive 2- and 3-jet events of the azimuthal correlation between the two jets with the largest transverse momenta, Delta phi(12), is presented. The measurement considers events where the two leading jets are nearly collinear ("back-to-back") in the transverse plane and is performed for several ranges of the leading jet transverse momentum. Proton-proton collision data collected with the CMS experiment at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 35.9 fb(-1) are used. Predictions based on calculations using matrix elements at leading-order and next-to-leading-order accuracy in perturbative quantum chromodynamics supplemented with leading-log parton showers and hadronization are generally in agreement with themeasurements. Discrepancies between the measurement and theoretical predictions are as large as 15%, mainly in the region 177 degrees <Delta phi(12) <180 degrees. The 2- and 3-jet measurements are not simultaneously described by any of models.Peer reviewe

Measurement of charged particle spectra in minimum-bias events from proton-proton collisions at root s =13 TeV

Pseudorapidity, transverse momentum, and multiplicity distributions are measured in the pseudorapidity range vertical bar eta vertical bar 0.5 GeV in proton-proton collisions at a center-of-mass energy of root s = 13 TeV. Measurements are presented in three different event categories. The most inclusive of the categories corresponds to an inelastic pp data set, while the other two categories are exclusive subsets of the inelastic sample that are either enhanced or depleted in single diffractive dissociation events. The measurements are compared to predictions from Monte Carlo event generators used to describe high-energy hadronic interactions in collider and cosmic-ray physics.Peer reviewe

Measurement of prompt D0{\mathrm{D^0}} and D‾0{\mathrm{\overline{D}}{}^0} meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at sNN=\sqrt{s_\mathrm{NN}} = 5.02 TeV

International audienceThe strong Coulomb field created in ultrarelativistic heavy ion collisions is expected to produce a rapidity-dependent difference ( Δv2 ) in the second Fourier coefficient of the azimuthal distribution (elliptic flow, v2 ) between D0 ( u‾c ) and D‾0 ( uc‾ ) mesons. Motivated by the search for evidence of this field, the CMS detector at the LHC is used to perform the first measurement of Δv2 . The rapidity-averaged value is found to be 〈Δv2〉=0.001±0.001(stat)±0.003(syst) in PbPb collisions at sNN=5.02TeV . In addition, the influence of the collision geometry is explored by measuring the D0 and D‾0 mesons v2 and triangular flow coefficient ( v3 ) as functions of rapidity, transverse momentum ( pT ), and event centrality (a measure of the overlap of the two Pb nuclei). A clear centrality dependence of prompt D0 meson v2 values is observed, while the v3 is largely independent of centrality. These trends are consistent with expectations of flow driven by the initial-state geometry

Measurement of charged particle spectra in minimum-bias events from proton-proton collisions at s=\sqrt{s}= 13 TeV

Pseudorapidity, transverse momentum, and multiplicity distributions are measured in the pseudorapidity range $|\eta|$ 0.5 GeV in proton-proton collisions at a center-of-mass energy of $\sqrt{s} =$ 13 TeV. Measurements are presented in three different event categories. The most inclusive of the categories corresponds to an inelastic pp data set, while the other two categories are exclusive subsets of the inelastic sample that are either enhanced or depleted in single diffractive dissociation events. The measurements are compared to predictions from Monte Carlo event generators used to describe high-energy hadronic interactions in collider and cosmic-ray physics