Compact broadband high-resolution Compton spectroscopy for laser-driven high-flux gamma rays

A compact broadband Compton spectrometer with high spectral resolution has been designed to detect spectra of laser-driven high-flux gamma rays.The primary detection range of the gamma-ray spectrum is 0.5 MeV–13 MeV,although a secondary harder gamma-ray region of 13 MeV–30MeV can also be covered.The Compton-scattered electrons are spectrally resolved using a curved surface detector and a nonuniform magnetic field produced by a pair of step-like magnets.This design allows a compact structure,a wider bandwidth,especially in the lower-energy region of 0.5 MeV–2 MeV,and optimum spectral resolution.The spectral resolution is 5%–10%in the range 4 MeV–13 MeV and better than 25%in the range 0.5MeV–4MeV(with an Al converter of 0.25mmthickness and a collimator of 1 cm inner diameter).Low-Z plastic materials are used on the inner surface of the spectrometer to suppress noise due to secondary X-ray fluorescence.The spectrometer can be adjusted flexibly via a specially designed mechanical component.An algorithmbased on a regularizationmethod has also been developed to reconstruct the gamma-ray spectrum from the scattered electrons.

Microscopic nonlinear optical activities and ultrafast carrier dynamics in layered AgInP_(2)S_(6)

Since the emergence of graphene, transition metal dichalcogenides, and black phosphorus, two-dimensional materials have attracted significant attention and have driven the development of fundamental physics and optoelectronic devices. Metal phosphorus trichalcogenides(MPX3), due to their large bandgap of 1.3–3.5 eV, enable the extension of optoelectronic applications to visible and ultraviolet(UV) wavelengths.

Gamma-ray generation from ultraintense laser-irradiated solid targets with preplasma

In the laser plasma interaction of quantum electrodynamics(QED)-dominated regime,γ-rays are generated due to synchrotron radiation from high-energy electrons traveling in a strong background electromagnetic field.With the aid of2 D particle-in-cell code including QED physics,we investigate the preplasma effect on theγ-ray generation during the interaction between an ultraintense laser pulse and solid targets.We found that with the increasing preplasma scale length,theγ-ray emission is enhanced significantly and finally reaches a steady state.Meanwhile,theγ-ray beam becomes collimated.This shows that,in some cases,the preplasmas will be piled up acting as a plasma mirror in the underdense preplasma region,where theγ-rays are produced by the collision between the forward electrons and the reflected laser fields from the piled plasma.The piled plasma plays the same role as the usual reflection mirror made from a solid target.Thus,a single solid target with proper scale length preplasma can serve as a manufactural and robustγ-ray source.

Hydrothermal synthesis of two-dimensional MoS_(2)and its applications

Two-dimensional(2D)transition metal dichalcogenides(TMDs)have attracted tremendous attention because of their unique electronic,optical and chemical properties.2D TMDs,especially 2D MoS2,have been proved to show great potential in vari-ous applications such as sensing,hydrogen evolution and lithium ion batteries.Therefore,methods for the scalable preparation of 2D materials and 2D nanocomposites of high quality and low cost must be developed.Among the various synthesis meth-ods,the hydrothermal synthesis method is simple and can meet the above requirements.In this review,the recent advances in the controllable hydrothermal synthesis of 2D MoS_(2)and its nanocomposites by the hydrothermal synthesis method are highlighted.We provide insight into the growth mechanisms of few-layered 2D MoS_(2)with different morphologies and the key technologies to realize wafer-scale growth of continuous and homogeneous 2D films which are important for practical applications.Further,the typical applications of TMDs in nonlinear optics as ultrafast optical modulation devices are pre-sented based on work of our institute.For more clarity,we summarize the current challenges of the hydrothermal synthesis method encountering,and suggest solutions to these challenges concerning future developments in practical applications.