Hai-Feng Wang

Development and calibration of the Moon-based EUV Camera for Chang’e-3

The process of development and calibration for the first Moon-based extreme ultraviolet (EUV) camera to observe Earths plasmasphere is introduced and the design, test and calibration results are presented. The EUV camera is composed of a multilayer film mirror, a thin film filter, a photon-counting imaging detector, a mechanism that can adjust the direction in two dimensions, a protective cover, an electronic unit and a thermal control unit. The center wavelength of the EUV camera is 30.2 nm with a bandwidth of 4.6 nm. The field of view is 14.7 degrees with an angular resolution of 0.08 degrees, and the sensitivity of the camera is 0.11 count s(-1) Rayleigh(-1). The geometric calibration, the absolute photometric calibration and the relative photometric calibration are carried out under different temperatures before launch to obtain a matrix that can correct geometric distortion and a matrix for relative photometric correction, which are used for in-orbit correction of the images to ensure their accuracy.

Mapping the Milky Way with LAMOST I: method and overview

We present a statistical method to derive the stellar density profiles of the Milky Way from spectroscopic survey data, taking into account selection effects. We assume the selection function, which can be altered during observations and data reductions, of the spectroscopic survey is based on photometric colors and magnitude. Then the underlying selection function for a line-of-sight can be recovered well by comparing the distribution of the spectroscopic stars in a color-magnitude plane with that of the photometric dataset. Subsequently, the stellar density profile along a line-of-sight can be derived from the spectroscopically measured stellar density profile multiplied by the selection function. The method is validated using Galaxia mock data with two different selection functions. We demonstrate that the derived stellar density profiles reconstruct the true ones well not only for the full set of targets, but also for sub-populations selected from the full dataset. Finally, the method is applied to map the density profiles for the Galactic disk and halo, using the LAMOST RGB stars. The Galactic disk extends to about R = 19 kpc, where the disk still contributes about 10% to the total stellar surface density. Beyond this radius, the disk smoothly transitions to the halo without any truncation, bending or breaking. Moreover, no over-density corresponding to the Monoceros ring is found in the Galactic anti-center direction. The disk shows moderate north–south asymmetry at radii larger than 12 kpc. On the other hand, the R–Z tomographic map directly shows that the stellar halo is substantially oblate within a Galactocentric radius of 20 kpc and gradually becomes nearly spherical beyond 30 kpc.

A model for thickness effect on the band gap of amorphous germanium film

A Mott-Davis-Paracrystalline model was proposed to interpret thickness effect of the band gap for amorphous germanium (a-Ge). We believe that a-Ge has a semiconductor-alloy-like structure, it may contain medium-range order (MRO) and continuous random network (CRN) simultaneously and there is a dependence of MRO/CRN ratio on film thickness and preparation methods/parameters. For MRO is dominant, thickness effect can be described by one-dimensional quantum confinement (ODQC) effect of nanocrystals and strain-induced shrinkage of the band gap; For CRN is dominant, thickness dependence can be interpreted by changes in the quality of a CRN and ODQC effect of nanoamorphous phase.

Mapping the Milky Way with LAMOST– III. Complicated spatial structure in the outer disc

We present {complexity} of the Galactic outer disc {by fitting the stellar volume densities of the red giant branch stars with a two-disc component model}. {The discs are confirmed to} extend to

3D Asymmetrical motions of the Galactic outer disc with LAMOST K giant stars

R\sim19

Design and fabrication of far ultraviolet filters based on π-multilayer technology in high- k materials

\,kpc. The radial density profile of the discs shows {two breaks at

Detection of an ordered-structure fraction in amorphous silicon

R\sim11

In-situ and real time stress of 30.4 nm Mo/Si multilayer mirror for the moon-based EUV camera

and

Rediscovering the Galactic outer disk with LAMOST data

\sim14

Adhesion between submicrometer polystyrene spheres

\,kpc, respectively, which} separate the radial profile into three segments with different scale lengths of