Cross-correlation Forecast of CSST Spectroscopic Galaxy and MeerKAT Neutral Hydrogen Intensity Mapping Surveys

Cross-correlating the data on neutral hydrogen(HⅠ)21 cm intensity mapping with galaxy surveys is an effective method to extract astrophysical and cosmological information.In this work,we investigate the cross-correlation of MeerKAT single-dish mode HⅠintensity mapping and China Space Station Telescope(CSST)spectroscopic galaxy surveys.We simulate a survey area of~300 deg~2 of MeerKAT and CSST surveys at z=0.5 using MultiDark N-body simulation.The PC A algorithm is applied to remove the foregrounds of HⅠintensity mapping,and signal compensation is considered to solve the signal loss problem in HⅠ-galaxy cross power spectrum caused by the foreground removal process.We find that from CSST galaxy auto and MeerKAT-CSST cross power spectra,the constraint accuracy of the parameter productΩ_(HⅠ)b_(HⅠ)r_(HⅠ,g)can reach~1%,which is about one order of magnitude higher than the current results.After performing the full MeerKAT HⅠintensity mapping survey with5000 deg~2 survey area,the accuracy can be enhanced to<0.3%.This implies that the MeerKAT-CSST cross-correlation can be a powerful tool to probe the cosmic HⅠproperty and the evolution of galaxies and the Universe.

The operation and improvement of CSNS front end

Introduction Operation target beam power of China Spallation Neutron Source(CSNS),as the China's first 100 kW beam power pulsed neutron source,is now larger than 80 kW.During the beam power upgrading process of CSNS to 50 kW from 2018 to 2019,many improvements have been made for the front end of CSNS.Results The improvements mainly focus on solving the problems of ion source instability and the radio frequency quadrupole(RFQ)sparking caused by the pre-chopped beam into RFQ.

Search for invisible decays of the Higgs boson produced at the CEPC

The Circular Electron Positron Collider(CEPC),proposed as a future Higgs boson factory,will operate at a center-of-mass energy of 240 GeV and will accumulate 5.6 ab−1 of integrated luminosity in 7 years.In this study,we estimate the upper limit of BR(H→inv)for three independent channels,including two leptonic channels and one hadronic channel,at the CEPC.Based on the full simulation analysis,the upper limit of BR(H→inv)could reach 0.26%at the 95%confidence level.In the Stand Model(SM),the Higgs boson can only decay invisibly via H→ZZ∗→νν¯νν¯,so any evidence of invisible Higgs decays that exceed BR(H→inv)of the SM will indicate a phenomenon that is beyond the SM(BSM).The invariant mass resolution of the visible hadronic decay system ZH(Z→qq,H→inv)is simulated,and the physics requirement at the CEPC detector for reaching this is given.

Optical design and optimization study of metrology sector at high energy photon source

Introduction X-ray metrology,including the metrological calibration of X-ray detectors,optical elements and sources,is important for many frontier science,such as X-ray astronomy,EUV-lithography,plasma physics.Among many types of X-ray sources,synchrotron-radiation is considered perfect for X-ray metrology,mainly due to that arbitrarily X-rays specifications can be tailored to meet the demands of metrological calibration of X-ray detectors and optical elements.As a consequence,many metrology beamlines around the world are built,upgrading or to be constructed,including the metrology sector to be constructed at High Energy Photon Source(HEPS).Method One reasonable way to access good metrological data is using a stable X-ray beam,which means that beam position as well as flux should be as constant as possible and the beamline configuration should be simple and robust to reduce the uncertainty from beamline itself.In addition,the spectral purity of monochromatic X-rays is another crucial factor for X-ray metrology,which means stray X-rays and harmonic X-rays must be as low as possible.Many measures are taken to satisfy these requirements.Conclusion An optical design of the metrology sector optimized for synchrotron-radiation-based-metrology is described here.The metrology sector,ranging from 50 eV to 20 keV,will be set up to meet the growing needs of X-ray metrology in China.All beamlines’configurations are simple and easy to use,with an acceptable ratio of high-order harmonics and stray X-rays,which can be under 1%in the entire energy range.

Reduced graphene oxide/metal oxide nanoparticles composite membranes for highly efficient molecular separation

Graphene oxide（GO） membranes play an important role in various nanofiltration applications including desalination, water purification, gas separation, and pervaporation. However, it is still very challenging to achieve both high separation efficiency and good water permeance at the same time. Here, we synthesized two kinds of GO-based composite membranes i.e. reduced GO（rGO）@MoO2 and rGO@WO3 by in-situ growth of metal nanoparticles on the surface of GO sheets. They show a high separation efficiency of ～100% for various organic dyes such as rhodamine B, methylene blue and evans blue, along with a water permeance over 125 Lm（-2） h（-1） bar（-1）. The high water permeance and rejection efficiency open up the possibility for the real applications of our GO composite membranes in water purification and wastewater treatment. Furthermore, this composite strategy can be readily extended to the fabrication of other ultrathin molecular sieving membranes for a wide range of molecular separation applications.

Correction

Correction to:Semi-supervised Ladder Networks for Speech Emotion Recognition DOI:10.1007/sll633-019-1175-x Authors:Jian-Hua Tao,Jian Huang,Ya Li,Zheng Li-an,Ming-Yue Niu The article Semi-supervised Ladder Networks for Speech Emotion Recognition written by Jian-Hua Tao,Jian Huang,Ya Li,Zheng Lian and Ming-Yue Niu,was originally published on vol.16,no.4 of International Journal of Automation and Computing without Open Access.

Accurate reconstruction algorithm for bilateral differential phase signals

Background The differential phase computed tomography(DP-CT)imaging is a kind of X-ray-phase-based CT methods,which is widely used in various X-ray imaging laboratories.At present,a collection of projections with the horizontal direc-tion(perpendicular to the sample rotation axis)DP information is often acquired in DP-CT.In an ideal experiment,if the background is zero,then we can accurately reconstruct the information of each direction of the sample with horizontal data only.Actually,background information will produce streaking artifacts to affect the resolution in directions other than the horizontal direction.Purpose To mitigate the streaking artifacts in the conventionally reconstructed DP-CT images.Method This study develops a novel analytical DP-CT reconstruction framework by jointly using the bilateral DP information obtained along two perpendicular directions.In addition,a new data acquisition scheme is also proposed to quickly acquire the bilateral DP signal without the need of changing the direction of refraction signal acquisition.Results Experimental results demonstrate that this new algorithm is able to greatly reduce the streaking artifacts on DP-CT images.

Precision Higgs physics at the CEPC

The discovery of the Higgs boson with its mass around 125 GeV by the ATLAS and CMS Collaborations marked the beginning of a new era in high energy physics.The Higgs boson will be the subject of extensive studies of the ongoing LHC program.At the same time,lepton collider based Higgs factories have been proposed as a possible next step beyond the LHC,with its main goal to precisely measure the properties of the Higgs boson and probe potential new physics associated with the Higgs boson.The Circular Electron Positron Collider(CEPC)is one of such proposed Higgs factories.The CEPC is an e^+e^- circular collider proposed by and to be hosted in China.Located in a tunnel of approximately 100 km in circumference,it will operate at a center-of-mass energy of 240 GeV as the Higgs factory.In this paper,we present the first estimates on the precision of the Higgs boson property measurements achievable at the CEPC and discuss implications of these measurements.