Development of a balloon-born Peltier-based chilled-mirror hygrometer for the troposphere and the lower stratosphere

We have developed a new balloon-borne hygrometer, which is based on a chilled-mirror principle and uses a two stage Peltier cooler. In January 2012, we have conducted flight tests at Biak, Indonesia (1.180S, 136.110E) to evaluate the performances of this sensor. The result showed that this hygrometer has the ability to measure atmospheric water vapor from the surface to the lower stratosphere. It is considered that our hygrometer is helpful for TTL observation campaigns because of its ease-in-handling

Two-magnon excitations in resonant inelastic x-ray scattering studied by spin-density-wave formalism

We study two-magnon excitations in resonant inelastic x-ray scattering (RIXS) at the transition-metal $K$-edge. Instead of working with effective Heisenberg spin models, we work with a Hubbard-type model ($d$-$p$ model) for a typical insulating cuprate La$_2$CuO$_4$. For the antiferromagnetic ground state within the spin-density-wave (SDW) mean-field formalism, we calculate the dynamical correlation function within the random-phase approximation (RPA), and then obtain two-magnon excitation spectra by calculating the convolution of it. Coupling between the $K$-shell hole and the magnons in the intermediate state is calculated by means of diagrammatic perturbation expansion in the Coulomb interaction. Calculated momentum dependence of RIXS spectra agrees well with that of experiments. A notable difference from previous calculations based on the Heisenberg spin models is that RIXS spectra have a large two-magnon weight near the zone center, which may be confirmed by further careful high-resolution experiments.Comment: 16 pages, 7 figures. Accepted to Phys. Rev.