64 research outputs found
Point-contact spectroscopy of the nickel borocarbide superconductor YNi2B2C in the normal and superconducting state
Point-contact (PC) spectroscopy measurements of YNi2B2C single crystals in
the normal and superconducting (SC) state (T_c=15.4K) for the main
crystallographic directions are reported. The PC study reveals the
electron-phonon interaction (EPI) spectral function with dominant phonon
maximum around 12 meV and further weak structures (hump or kink) at higher
energy at about 50 meV. No "soft" modes below 12 meV are resolved in the normal
state. The PC EPI spectra are qualitatively similar for the different
directions. Contrary, directional study of the SC gap results in
\Delta_[100]=1.5 meV for the a direction and \Delta_[001]=2.3 meV along the c
axis; however the critical temperature T_c in PC in all cases is near to that
in the bulk sample. The value 2\Delta_[001]/kT_c=3.6 is close to the BCS value
of 3.52, and the temperature dependence \Delta_[001](T) is BCS-like, while the
for small gap \Delta_[100](T) is below BCS behavior at T>T_c/2 similarly as in
the two-gap superconductor MgB2. It is supposed that the directional variation
\Delta can be attributed to a multiband nature of the SC state in YNi2B2C.Comment: 9 pages, 10 figures, to be published in a special issue of J. Low
Temp. Phys. in honour of Prof. H. von Loehneyse
Revisiting Field Capacity (FC): variation of definition of FC and its estimation from pedotransfer functions
Method to estimate soil macroporosity and microporosity based on sand content and bulk density
Avaliação da intensidade de tráfego de tratores em alguns atributos físicos de um argissolo amarelo
Variabilidade espacial de atributos físicos de um Latossolo Vermelho sob cultivo de cana-de-açúcar
Qualidade física de um latossolo sob plantio direto influenciada pela cobertura do solo
Atributos físico-hídricos de um latossolo de cerrado em diferentes posições de amostragem na lavoura cafeeira
Diatomáceas perifíticas da represa Itaqui, São José dos Pinhais, Paraná: Fragilariales, Eunotiales, Achnanthales e Gomphonema Ehrenberg
Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck . I. Construction of CMB lensing maps and modeling choices
Joint analyses of cross-correlations between measurements of galaxy positions, galaxy lensing, and lensing of the cosmic microwave background (CMB) offer powerful constraints on the large-scale structure of the Universe. In a forthcoming analysis, we will present cosmological constraints from the analysis of such cross-correlations measured using Year 3 data from the Dark Energy Survey (DES), and CMB data from the South Pole Telescope (SPT) and Planck. Here we present two key ingredients of this analysis: (1) an improved CMB lensing map in the SPT-SZ survey footprint and (2) the analysis methodology that will be used to extract cosmological information from the cross-correlation measurements. Relative to previous lensing maps made from the same CMB observations, we have implemented techniques to remove contamination from the thermal Sunyaev Zel’dovich effect, enabling the extraction of cosmological information from smaller angular scales of the cross-correlation measurements than in previous analyses with DES Year 1 data. We describe our model for the cross-correlations between these maps and DES data, and validate our modeling choices to demonstrate the robustness of our analysis. We then forecast the expected cosmological constraints from the galaxy survey-CMB lensing auto and cross-correlations. We find that the galaxy-CMB lensing and galaxy shear-CMB lensing correlations will on their own provide a constraint on
S
8
=
σ
8
√
Ω
m
/
0.3
at the few percent level, providing a powerful consistency check for the DES-only constraints. We explore scenarios where external priors on shear calibration are removed, finding that the joint analysis of CMB lensing cross-correlations can provide constraints on the shear calibration amplitude at the 5% to 10% level
Joint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck . II. Cross-correlation measurements and cosmological constraints
Cross-correlations of galaxy positions and galaxy shears with maps of gravitational lensing of the cosmic microwave background (CMB) are sensitive to the distribution of large-scale structure in the Universe. Such cross-correlations are also expected to be immune to some of the systematic effects that complicate correlation measurements internal to galaxy surveys. We present measurements and modeling of the cross-correlations between galaxy positions and galaxy lensing measured in the first three years of data from the Dark Energy Survey with CMB lensing maps derived from a combination of data from the
2500
deg
2
SPT-SZ survey conducted with the South Pole Telescope and full-sky data from the Planck satellite. The CMB lensing maps used in this analysis have been constructed in a way that minimizes biases from the thermal Sunyaev Zel’dovich effect, making them well suited for cross-correlation studies. The total signal-to-noise of the cross-correlation measurements is 23.9 (25.7) when using a choice of angular scales optimized for a linear (nonlinear) galaxy bias model. We use the cross-correlation measurements to obtain constraints on cosmological parameters. For our fiducial galaxy sample, which consist of four bins of magnitude-selected galaxies, we find constraints of
Ω
m
=
0.272
+
0.032
−
0.052
and
S
8
≡
σ
8
√
Ω
m
/
0.3
=
0.736
+
0.032
−
0.028
(
Ω
m
=
0.245
+
0.026
−
0.044
and
S
8
=
0.734
+
0.035
−
0.028
) when assuming linear (nonlinear) galaxy bias in our modeling. Considering only the cross-correlation of galaxy shear with CMB lensing, we find
Ω
m
=
0.270
+
0.043
−
0.061
and
S
8
=
0.740
+
0.034
−
0.029
. Our constraints on
S
8
are consistent with recent cosmic shear measurements, but lower than the values preferred by primary CMB measurements from Planck
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