arXiv subjects

M. Y. Wu

Publications and source records attributed to M. Y. Wu.

3 recordsLinked to original sources

arXiv2026

A three-step proposal for searching for light shining through walls in the X-ray band at the High Energy Photon Source

Despite compelling observational evidence for dark matter (DM), its fundamental physical properties remain poorly understood. In this report, we propose a three-step light-shining-through-walls (LSW) experimental scheme utilizing the high-brilliance, high-energy X-rays from the ID21 Hard X-ray Imaging Beamline at the High Energy Photon Source (HEPS) to search for signatures of dark photons (DPs) and other weakly interacting slim particles (WISPs). The scheme includes three steps of LSW experiments: a short-term (several days) dedicated exposure experiment, a long-term (several years) synchronous accompanying experiment, and a WISP detection with strong magnetic fields. Projection results show that this HEPS-based LSW experiment can effectively constrain DP parameters in the 1 eV--400 keV mass range, covering unexploited parameter space of the existing X-ray LSW experiments. It provides a least model-dependent and most purely-laboratory approach for probing dark sector particles and advancing new physics research beyond the Standard Model gradually.

hep-ex↗

arXiv2018

Characterization of Pd/Y multilayers with B4C barrier layers using GIXR and x-ray standing wave enhanced HAXPES

Pd/Y multilayers are high reflectance mirrors designed to work in the 7.5-11 nm wavelength range. Samples, prepared by magnetron sputtering, are deposited with or without B4C barrier layers located at the interfaces of Pd and Y layers to reduce interdiffusion, which is expected by calculating mixing enthalpy of Pd and Y. Grazing incident x-ray reflectometry is used to characterize these multilayers. B4C barrier layers are found effective on reducing the Pd-Y interdiffusion. Details of the composition of the multilayers are revealed by hard x-ray photoemission spectroscopy under x-ray standing waves effect. It consists in measuring the photoemission intensity from samples that perform an angular scan in the region corresponding to the multilayer period and the incident photon energy according to the Bragg law. The experimental result indicates that Pd does not chemically react with B nor C at the Pd-B4C interfaces while Y does at the Y-B4C interfaces. The formation of Y-B or Y-C chemical compound can be the reason why the interfaces are stabilized. By comparing the experimentally obtained angular variation of the characteristic photoemission with the theoretical calculation, the depth distribution of each component element can be interpreted.

physics.app-ph↗

arXiv2001

The complex superstructure in Mg1-xAlxB2 at x~0.5

Electron diffraction and high resolution microscopy have been performed on Mg1-xAlxB2 with x~0.5. This composition displays a superstructure with a repeat period of exactly 2c along the c axis and about 10 nm in the a-b plane. The superstructure results in ring-shaped superreflections in the diffraction pattern. Irradiation by a strong electron beam results in a loss of the superstructure and a decrease of about 1% in the c lattice parameter. In-situ heating and cooling on the other hand showed that the superstructure is stable from 100 K to 700 K. Possible origins for the superstructure are proposed.

cond-mat↗