Probing the peripheral self-generated magnetic field distribution in laser-plasma magnetic reconnection with Martin-Puplett interferometer polarimeter

Magnetic reconnection of the self-generated magnetic fields in laser-plasma interaction is an important laboratory method for modeling high-energy density astronomical and astrophysical phenomena.We use the Martin-Puplett interferometer(MPI)polarimeter to probe the peripheral magnetic fields generated in the common magnetic reconnection configuration,two separated coplanar plane targets,in laser-target interaction.We introduce a new method that can obtain polarization information from the interference pattern instead of the sinusoidal function fitting of the intensity.A bidirectional magnetic field is observed from the side view,which is consistent with the magneto-hydro-dynamical(MHD)simulation results of self-generated magnetic field reconnection.We find that the cancellation of reverse magnetic fields after averaging and integration along the observing direction could reduce the magnetic field strength by one to two orders of magnitude.It indicates that imaging resolution can significantly affect the accuracy of measured magnetic field strength.

Preliminary analysis of fuel cycle performance for a small modular heavy water-moderated thorium molten salt reactor

Heavy water-moderated molten salt reactors(HWMSRs)are novel molten salt reactors that adopt heavy water rather than graphite as the moderator while employing liquid fuel.Owing to the high moderating ratio of the heavy water moderator and the utilization of liquid fuel,HWMSRs can achieve a high neutron economy.In this study,a large-scale small modular HWMSR with a thermal power of 500 MWth was proposed and studied.The criticality of the core was evaluated using an in-house critical search calculation code(CSCC),which was developed based on Standardized Computer Analyses for Licensing Evaluation,version 6.1.The preliminary fuel cycle performances(initial conversion ratio(CR),initialfissile fuel loading mass,and temperature coefficient)were investigated by varying the lattice pitch(P)and the molten salt volume fraction(VF).The results demonstrate that the temperature coefficient can be negative over the range of investigated Ps and VFs for both 233U-Th and LEU-Th fuels.A core with a P of 20 cm and a VF of 20%is recommended for 233U-Th and LEU-Th fuels to achieve a high performance of initial CR and fuel loading.Regarding TRU-Th fuel,a core with a smaller P(~5 cm)and larger VF(~24%)is recommended to obtain a negative temperature coefficient.

An algorithm to resolve γ-rays from charged cosmic rays with DAMPE

The DArk Matter Particle Explorer（DAMPE）,also known as Wukong in China,which was launched on 2015 December 17,is a new high energy cosmic ray and γ-ray satellite-borne observatory.One of the main scientific goals of DAMPE is to observe Ge V-Te V high energy γ-rays with accurate energy,angular and time resolution,to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to γ-rays,it is challenging to identify γ-rays with sufficiently high efficiency,minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify γ-rays in DAMPE data based on Monte Carlo simulations,using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected γ-ray events at～10 Ge V amounts to less than 1% of the selected sample.Finally,we use flight data to verify the effectiveness of the method by highlighting known γ-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar.

Characteristics of combustion zone and evolution of mineral phases along bed height in ore sintering

Quantitative parameters of bed combustion, including the thickness of the combustion zone(TCZ), the maximum temperature of the combustion zone(MTCZ), and the bed shrinkage, were characterized through a series of sinter pot tests in transparent quartz pots. The results showed that TCZ first ascended and then descended as the sintering process proceeded. The sintering process was divided into four stages according to the variation rate of the TCZ. A "relative-coordinate" method was developed to obtain the actual reaction temperature of sinter along the height direction. With increasing the sintering temperature, the reactants transformed and entered into liquid phases. The mineral composition and microstructure of the sinter were characterized through X-ray diffraction and scanning electron microscopy–energy-dispersive X-ray spectroscopy. Liquid phases with greater Fe and Al contents were more likely to form acicular-like silico-ferrite of calcium and aluminum after crystallization because of the outward spread of Al, which led to a better fluidity of the liquid. An evolution mechanism of "solid-state reaction—liquid phases formation—crystallization" of the mineral phases is proposed.

A method for aligning the plastic scintillator detector on DAMPE

The Plastic Scintillator Detector(PSD) onboard the DArk Matter Particle Explorer(DAMPE)is designed to measure cosmic ray charge(Z) and to act as a veto detector for gamma ray identification.To fully exploit the charge identification potential of PSD and to enhance its capability to identify gamma ray events, we develop an alignment method for the PSD. The path length of a given track in the volume of a PSD bar is derived taking into account the shift and rotation alignment corrections. By examining energy spectra of corner-passing events and fully contained events, position shifts and rotations of all PSD bars are obtained, and are found to be on average about 1 mm and 0.0015 radian respectively. To validate the alignment method, we introduce artificial shifts and rotations of PSD bars into the detector simulation.These shift and rotation parameters can be recovered successfully by the alignment procedure. As a result of the PSD alignment procedure, the charge resolution of the PSD is improved from 4% to 8%, depending on the nuclei.

Comparison of Proton Shower Developments in the BGO Calorimeter of the Dark Matter Particle Explorer between GEANT4 and FLUKA Simulations

The DArk Matter Particle Explorer(DAMPE)is a satellite-borne detector for high-energy cosmic rays and y-rays.To fully understand the detector performance and obtain reliable physical results,extensive simulations of the detector are necessary.The simulations are particularly important for the data analysis of cosmic ray nuclei,which relies closely on the hadronic and nuclear interactions of particles in the detector material.Widely adopted simulation softwares include the GEANT4 and FLUKA,both of which have been implemented for the DAMPE simulation tool.Here we describe the simulation tool of DAMPE and compare the results of proton shower properties in the calorimeter from the two simulation softwares.Such a comparison gives an estimate of the most significant uncertainties of our proton spectral analysis.

Calibration of the DAMPE Plastic Scintillator Detector and its on-orbit performance

The DArk Matter Particle Explorer(DAMPE) is a space-borne apparatus for detecting the highenergy cosmic-ray-like electrons, γ-rays, protons and heavy ions. The Plastic Scintillator Detector(PSD)is the top-most sub-detector of the DAMPE. The PSD is designed to measure the charge of incident highenergy particles and it also serves as a veto detector for discriminating γ-rays from charged particles. In this paper, a PSD on-orbit calibration procedure is described, which includes the five steps of pedestal, dynode correlation, response to minimum-ionizing particles, light attenuation function and energy reconstruction.A method for reconstructing the charge of incident high energy cosmic-ray particles is introduced. The detection efficiency of each PSD strip is verified to be above 99.5%; the total efficiency of the PSD for charged particles is above 99.99%.

Ultrafast two-dimensional x-ray imager with temporal fiducial pulses for laser-produced plasmas

It is challenging to make an ultrafast diagnosis of the temporal evolution of small and short-lived plasma in two dimensions. To overcome this difficulty, we have developed a well-timed diagnostic utilizing an x-ray streak camera equipped with a row of multi-pinhole arrays. By processing multiple sets of one-dimensional streaked image data acquired from various pinholes, we are capable of reconstructing high-resolution two-dimensional images with a temporal resolution of 38 ps and a spatial resolution of 18 μm. The temporal fiducial pulses accessed from external sources can advance the precise timing and accurately determine the arrival time of the laser. Moreover, it can correct the nonlinear sweeping speed of the streak camera. The effectiveness of this diagnostic has been successfully verified at the Shenguang-II laser facility,providing an indispensable tool for observing complex physical phenomena, such as the implosion process of laser-fusion experiments.

The Potential Effects and Use of Chinese Herbal Medicine Pine Pollen(Pinus pollen):A Bibliometric Analysis of Pharmacological and Clinical Studies

The objectives of this study are to conduct a comprehensive literature search and bibliometric analysis to identify the breadth and volume of pharmacological and clinical studies on pine pollen(Pinus pollen)and to identify the potential effects and the use of pine pollen.Three Chinese electronic databases and two English electronic databases were searched for pharmacological and clinical studies on pine pollen.Data were extracted and analyzed and included publication year,authors,study type,pharmacological research topics or clinical diseases/conditions,usage and type of preparation,authors’conclusions,and adverse effects.Of 239 publications identified,180 were pharmacological studies,37 were clinical trials,and 22 were reviews.Numbers of publications increased particularly from 2004 onward.The top 10 most frequent topics in pharmacological studies were immune regulation,antisenility,antioxidation,liver protection,inhibiting prostate hyperplasia,inhibiting tumor cell proliferation,lowering blood glucose,lowering blood lipids,antifatigue,and improving intestinal function.The top 10 most frequent clinical diseases treated or where pine pollen was used as an adjuvant were bedsores,diaper dermatitis,hyperlipidemia,oral mucositis,eczema,hyperplasia of prostate,hypertension,prostatitis,type 2 diabetes mellitus,and radiodermatitis.Eight trials reported no adverse events associated with pine pollen,one reported mild gastrointestinal reactions,but symptoms disappeared without special management.There have been an increasing number of publications on pine pollen during the past 20 years.Pharmacological studies have shown many potential benefits,and clinical studies have indicated some positive effects when it is either used as a single herb or as an adjuvant to treat disease.Its use as a topical agent,especially for skin diseases,was notable.

Implications on the origin of cosmic rays in light of 10 TV spectral softenings

Precise measurements of the energy spectra of cosmic rays(CRs)show various kinds of features deviating from single power-laws,which give very interesting and important implications on their origin and propagation.Previous measurements from a few balloon and space experiments indicate the existence of spectral softenings around 10 TV for protons(and probably also for Helium nuclei).Very recently,the DArk Matter Particle Explorer(DAMPE)measurement about the proton spectrum clearly reveals such a softening with a high significance.Here we study the implications of these new measurements,as well as the groundbased indirect measurements,on the origin of CRs.We find that a single component of CRs fails to fit the spectral softening and the air shower experiment data simultaneously.In the framework of multiple components,we discuss two possible scenarios,the multiple source population scenario and the background plus nearby source scenario.Both scenarios give reasonable fits to the wide-band data from TeV to 100 PeV energies.Considering the anisotropy observations,the nearby source model is favored.