bluuebunny/crossref_metadata_2025 huggingface dataset:
Poling-induced inverse time-dependent microstrain mechanisms and post-poling relaxation in bismuth ferrite
Authors: Liu Lisha , Rojac Tadej , Kimpton Justin , Walker Julian , Makarovic Maja , Li Jing-Feng , Daniels John
Published: March 2020

Domain-wall dynamics under strong, super-coercive electric fields in polycrystalline bismuth ferrite (BiFeO3) are not well established due to the experimental difficulties in processing high phase purity perovskite with low electrical conductivity. Overcoming these difficulties, here we present x-ray diffraction measurements carried out in situ during electrical poling with a trapezoidal electric-field to investigate the domain wall dynamics and lattice strain in this material. It is observed that during field ramping, microscopic strains, i.e., non-180° domain texture and lattice strain, increase simultaneously. During DC field dwell, however, a lattice strain decrease occurs over time, accompanied by an increase in the non-180° domain texture. This inverse time-dependent trend of microscopic strain mechanisms is speculated to be due to mobile charged defects residing in domain wall regions. The configuration of these charged point defects may also play a role in the observed post-poling relaxations of non-180° domain texture and macroscopic piezoelectric coefficients on removal of the field. Since conducting domain walls have been recently identified in a number of ferroelectrics, these results should significantly impact the understanding of strain mechanisms not only in BiFeO3 but on a broader range of ferroelectric materials.
Solid-State NMR, X-Ray Diffraction, and Theoretical Studies of Neutral Mononuclear Molecular Bis(triphenylphosphine)silver(I) Mono-Carboxylate and -Nitrate Systems
Authors: Grabowsky Simon , White Allan H. , Healy Peter C. , Lapere Kim M. , Ng Seik Weng , Skelton Brian W. , Wild Duncan A. , Bowmaker Graham A. , Hanna John V.
Published: March 2020

Neutral mononuclear molecular silver(i) carboxylate complexes of the form [(Ph3P)2Ag(O2XY)] with O2XY=O2CCH2Ph, O2CCHPh2, O2CC(CH3)3, O2CCH2C(CH3)3, and O2CCF3 (compounds 1–4 and 5β) have been investigated in the solid state using single-crystal X-ray structure determinations, 1D 31P CPMAS NMR and 2D 31P–31P CPCOSY NMR measurements, and ab initio computational modelling. The results show that these complexes contain P2AgO2 molecular cores with four-coordinate silver in which the carboxylate ligands are weakly bound to the silver atoms via the two oxygen atoms giving rise to unsymmetrical chelate units. Crystal structure determinations and solid-state NMR spectra have also been analysed for the mononuclear molecular silver(i) nitrate complex [(Ph3P)2Ag(O2NO)] (9α) and two polymorphs of its toluene monosolvate (11α, β). In 9α, the two PPh3 ligands are of the same chirality, whereas in 11α, β, they are opposed. The crystalline environments in the polymorphs have been explored by way of Hirshfeld surface analyses, after quantum-mechanical isolated-molecule calculations had shown that although the molecular energies of the experimental geometries of 9α, and 11α, β are significantly different from each other and from the energies of the optimized geometries, the latter, in contrast, do not differ significantly from each other despite the conformational isomerism. It has further been shown using 9α as an example that the energy dependence on variation of the P–Ag–P angle over a range of ~15° is only ~5 kJ mol−1. All this indicates that the forces arising from crystal packing result in significant perturbations in the experimental geometries, but do not alter the stereoisomerism caused by the donor atom array around the Ag atom. In the NMR study, a strong inverse correlation has been found between 1J(107/109Ag,31P) and the Ag–P bond length across all carboxylate and nitrate compounds.
African freshwater eel species (Anguilla spp.) identification through DNA barcoding
Authors: Hanzen Céline , Lucas Martyn C. , O'Brien Gordon , Downs Colleen T. , Willows-Munro Sandi
Published: March 2020

Freshwater eels (Anguilla spp.) have a long and complex catadromous life cycle. This unique feature, coupled with difficulty in separating species based on morphology, makes them complex targets for conservation. In this study we evaluated the utility of DNA barcoding using cytochrome oxidase I (COI) to delimit the four species of African eels found in the western Indian Ocean region. We collected 76 individual fin clips from the four eel species (A. mossambica, n=51; A. marmorata, n=17; A. bengalensis, n=6; A. bicolor, n=2) in the rivers of KwaZulu–Natal, South Africa, in 2016–18. Phylogenetic analysis of the COI sequences recovered all four species as monophyletic. Barcoding gap analyses were performed and there was no found overlap in inter- and intraspecific genetic distances. Consequently, the use of COI barcoding as an identification tool was found to be reliable for identifying African eels to the species level, which suggests that this marker should be included in future environmental DNA or metabarcoding studies.
Academic vocabulary and collocations used in language teaching and applied linguistics textbooks
Authors: Gholaminejad Razieh , Anani Sarab Mohammad Reza
Published: March 2020

Somewhere between technical and general vocabulary are located those words which are used in formal academic
contexts with a high frequency across scientific disciplines (Farrell 1990). These are
referred to as academic vocabulary. Recent findings do not support the adequacy of a single academic wordlist which can equally
meet the needs of students of all disciplines (Durrant 2016), and this has inspired
researchers to develop wordlists specific to each discipline. Language Teaching and Applied Linguistics is a discipline which
often embraces a high number of non-English speaking students for whom it is a demanding task to engage in academic communication
without having access to a ready-made resource. In the present study, a 10,781,188-word corpus based on textbooks taught in
thirteen subject areas of this field was compiled. The corpus was characterized by a specified genre and time-span, and a large
representative scope. It was used to draw up a list of academic words (= terminology) for students of this field. The wordlist,
which is accompanied by a list of collocations, accounts for approximately 7.1% of the coverage in the corpus. The findings build
on the trend toward generation of field-specific academic wordlists, which have significant implications for students,
instructors, material developers and researchers.
Why inequality persists in Africa
Authors: Obeng-Odoom Franklin
Published: March 2020

How to explain persistent inequality in Africa and its widespread consequences of uncertainty and social costs continues to be the focus of heated debate. In this debate piece, I argue that the contending orthodox, heterodox and political economy explanations are not satisfactory. Instead, stratification economics, centred on property and institutions, offers a more compelling elucidation of why stratification and inequality persist in Africa.
On linearised vacuum constraint equations on Einstein manifolds*
Authors: Beig Robert , Chruściel Piotr T
Published: March 2020

We show how to parameterise solutions of the general relativistic vector constraint equation on Einstein manifolds by unconstrained potentials. We provide a similar construction for the trace-free part of tensors satisfying the linearised scalar constraint. Previous work of ours has provided similar different constructions for solutions of the linearized constraints in the case where the cosmological constant Λ is zero. We use our new potentials to show that one can shield linearised gravitational fields using linearised gravitational fields without imposing the TT gauge (as done in previous work), for any value of

Λ
∈
R

.
Roadmap on multiscale materials modeling
Authors: van der Giessen Erik , Schultz Peter A , Bertin Nicolas , Bulatov Vasily V , Cai Wei , Csányi Gábor , Foiles Stephen M , Geers M G D , González Carlos , Hütter Markus , Kim Woo Kyun , Kochmann Dennis M , LLorca Javier , Mattsson Ann E , Rottler Jörg , Shluger Alexander , Sills Ryan B , Steinbach Ingo , Strachan Alejandro , Tadmor Ellad B
Published: March 2020

Modeling and simulation is transforming modern materials science, becoming an important tool for the discovery of new materials and material phenomena, for gaining insight into the processes that govern materials behavior, and, increasingly, for quantitative predictions that can be used as part of a design tool in full partnership with experimental synthesis and characterization. Modeling and simulation is the essential bridge from good science to good engineering, spanning from fundamental understanding of materials behavior to deliberate design of new materials technologies leveraging new properties and processes. This Roadmap presents a broad overview of the extensive impact computational modeling has had in materials science in the past few decades, and offers focused perspectives on where the path forward lies as this rapidly expanding field evolves to meet the challenges of the next few decades. The Roadmap offers perspectives on advances within disciplines as diverse as phase field methods to model mesoscale behavior and molecular dynamics methods to deduce the fundamental atomic-scale dynamical processes governing materials response, to the challenges involved in the interdisciplinary research that tackles complex materials problems where the governing phenomena span different scales of materials behavior requiring multiscale approaches. The shift from understanding fundamental materials behavior to development of quantitative approaches to explain and predict experimental observations requires advances in the methods and practice in simulations for reproducibility and reliability, and interacting with a computational ecosystem that integrates new theory development, innovative applications, and an increasingly integrated software and computational infrastructure that takes advantage of the increasingly powerful computational methods and computing hardware.
Growth and evolution of tetracyanoquinodimethane and potassium coadsorption phases on Ag(111)
Authors: Haags Anja , Rochford Luke A , Felter Janina , Blowey Phil J , Duncan David A , Woodruff D Phil , Kumpf Christian
Published: March 2020

Alkali-doping is a very efficient way of tuning the electronic properties of active molecular layers in (opto-) electronic devices based on organic semiconductors. In this context, we report on the phase formation and evolution of charge transfer salts formed by 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ) in coadsorption with potassium on a Ag(111) surface. Based on an in-situ study using low energy electron microscopy and diffraction we identify the structural properties of four phases with different stoichiometries, and follow their growth and inter-phase transitions. We label these four phases α to δ, with increasing K content, the last two of which (γ and δ-phases) have not been previously reported. During TCNQ deposition on a K-precovered Ag(111) surface we find a superior stability of δ-phase islands compared to the γ-phase; continued TCNQ deposition leads to a direct transition from the δ to the β-phase when the K : TCNQ ratio corresponding to this phase regime is reached, with no intermediate γ-phase formation. When, instead, K is deposited on a surface precovered with large islands of the low density commensurate (LDC) TCNQ phase that are surrounded by a TCNQ 2D-gas, we observe two different scenarios: on the one hand, in the 2D-gas phase regions, very small α-phase islands are formed (close to the resolution limit of the microscope, 10–15 nm), which transform to β-phase islands of similar size with increasing K deposition. On the other hand, the large (micrometer-sized) TCNQ islands transform directly to similarly large single-domain β-phase islands, the formation of the intermediate α-phase being suppressed. This frustration of the LDC-to-α transition can be lifted by performing the experiment at elevated temperature. In this sense, the morphology of the pure TCNQ submonolayer is conserved during phase transitions.
Single-order soft x-ray spectra with spectroscopic photon sieve*
Authors: Gao Yu-Lin , Wei Lai , Zhang Qiang-Qiang , Yang Zu-Zua , Zhou Wei-Min , Cao Lei-Feng
Published: March 2020

A single-order diffraction transmission grating named spectroscopic photon sieve (SPS) for soft x-ray region is proposed and demonstrated in this paper. The SPS consists of many circular pinholes located randomly, and can realize both free-standing diffractions and the suppression of higher-order differations. In this paper, the basic concept, numerical simulations, and calibration results of a 1000-lines/mm SPS for soft x-ray synchrotron radiation are presented. As predicted by theoretical calculations, the calibration results of a 1000-lines/mm SPS verify that the higher-order diffractions can be significantly suppressed along the symmetry axis. With the current nanofabrication technique, the SPS can potentially have a higher line density, and can be widely used in synchrotron radiation, laser-induced plasma diagnostics, and astrophysics.
Effect of deposition temperature on SrFe12O19@carbonyl iron core–shell composites as high-performance microwave absorbers
Authors: Liu Yuan , Li Rong , Jia Ying , He Zhen-Xin
Published: March 2020

The SrFe12O19@carbonyl iron (CI) core–shell composites used in microwave absorption are prepared by the metal–organic chemical vapor deposition (MOCVD). The x-ray diffractometer, scanning electron microscope, energy dispersive spectrometer, and vector network analyzer are used to characterize the structural, electromagnetic, and absorption properties of the composites. The results show that the SrFe12O19@CI composites with a core–shell structure could be successfully prepared under the condition: deposition temperatures above 180 °C, deposition time 30 min, and gas flow rate 30 mL/min. The electromagnetic properties of the composites change significantly, and their absorption capacities are improved. Of the obtained samples, those samples prepared at a deposition temperature of 180 °C exhibit the best absorption performance. The reflection loss of SrFe12O19@CI (180 °C) with 1.5 mm–2.5 mm in thickness is less than −10 dB in a frequency range of 8 GHz–18 GHz, which covers the whole X band and Ku band.
Asynchronism of the spreading dynamics underlying the bursty pattern*
Authors: Wang Tong , Zhou Ming-Yang , Fu Zhong-Qian
Published: March 2020

The potential mechanisms of the spreading phenomena uncover the organizations and functions of various systems. However, due to the lack of valid data, most of early works are limited to the simulated process on model networks. In this paper, we track and analyze the propagation paths of real spreading events on two social networks: Twitter and Brightkite. The empirical analysis reveals that the spreading probability and the spreading velocity present the explosive growth within a short period, where the spreading probability measures the transferring likelihood between two neighboring nodes, and the spreading velocity is the growth rate of the information in the whole network. Besides, we observe the asynchronism between the spreading probability and the spreading velocity. To explain the interesting and abnormal issue, we introduce the time-varying spreading probability into the susceptible-infected (SI) and linear threshold (LT) models. Both the analytic and experimental results reproduce the spreading phenomenon in real networks, which deepens our understandings of spreading problems.
Magnetoacoustic position imaging for liquid metal in animal interstitial structure*
Authors: Zhao Xiao-He , Liu Guo-Qiang , Xia Hui , Li Yan-Hong
Published: March 2020

Magnetoacoustic tomography with magnetic induction (MAT-MI), as a new kind of in-vivo imaging method, has potential application value in interstitial fluid research. In this paper, we propose the application of MAT-MI with liquid metal serving as a tracer of the interstitial structure to study its fluid behavior, and use it to implement the positional imaging of the spatial distribution of liquid metal. Owing to the particularity of liquid metal magnetoacoustic pressure (MAP) signals, we propose an envelope analysis method to extract the rising edge of the amplitude envelope of the detected waveform as effective position data. And for the first time, we propose the method of superpositing pixel matrix to achieve the position imaging of liquid metal. Finally, the positional imaging of the liquid metal sample embedded in the gel is achieved to have relatively accurate results. This study provides a method of effectively extracting data and implementing the position imaging for liquid metal in the interstitial structure in the frame of MAT-MI.
Experimental study on energy characteristics and ignition performance of recessed multichannel plasma igniter*
Authors: Cai Bang-Huang , Song Hui-Min , Jia Min , Wu Yun , Cui Wei , Huang Sheng-Fang
Published: March 2020

In the extreme conditions of high altitude, low temperature, low pressure, and high speed, the aircraft engine is prone to flameout and difficult to start secondary ignition, which makes reliable ignition of combustion chamber at high altitude become a worldwide problem. To solve this problem, a kind of multichannel plasma igniter with round cavity is proposed in this paper, the three-channel and five-channel igniters are compared with the traditional ones. The discharge energy of the three igniters was compared based on the electric energy test and the thermal energy test, and ignition experiments was conducted in the simulated high-altitude environment of the component combustion chamber. The results show that the recessed multichannel plasma igniter has higher discharge energy than the conventional spark igniter, which can increase the conversion efficiency of electric energy from 26% to 43%, and the conversion efficiency of thermal energy from 25% to 73%. The recessed multichannel plasma igniter can achieve greater spark penetration depth and excitation area, which both increase with the increase of height. At the same height, the inlet flow helps to increase the penetration depth of the spark. The recessed multichannel plasma igniter can widen the lean ignition boundary, and the maximum enrichment percentage of lean ignition boundary can reach 31%.
Existence of spontaneous symmetry breaking in two-lane totally asymmetric simple exclusion processes with an intersection*
Authors: Tian Bo , Xia Ping , Liu Li , Wu Meng-Ran , Guo Shu-Yong
Published: March 2020

We study two-lane totally asymmetric simple exclusion processes (TASEPs) with an intersection. Monte Carlo simulations show that only symmetric phases exist in the system. To verify the existence of asymmetric phases, we carry out a cluster mean-field analysis. Analytical results show that the densities of the two upstream segments of the intersection site are always equal, which indicates that the system is not in asymmetric phases. It demonstrates that the spontaneous symmetry breaking does not exist in the system. The density profiles and the boundaries of the symmetric phases are also investigated. We find that the cluster mean-field analysis shows better agreement with simulations than the simple mean-field analysis where the correlation of sites is ignored.
Growth and structural characteristics of metastable β-In2Se3 thin films on H-terminated Si(111) substrates by molecular beam epitaxy*
Authors: Shen Yi-Fan , Yin Xi-Bo , Xu Chao-Fan , He Jing , Li Jun-Ye , Li Han-Dong , Zhu Xiao-Hong , Niu Xiao-Bin
Published: March 2020

Epitaxial growth and structural characteristics of metastable β-In2Se3 thin films on H-terminated Si(111) substrates are studied. The In2Se3 thin films grown below the β-to-α phase transition temperature (453 K) are characterized to be strained β-In2Se3 mixed with significant γ-In2Se3 phases. The pure-phased single-crystalline β-In2Se3 can be reproducibly achieved by in situ annealing the as-deposited poly-crystalline In2Se3 within the phase equilibrium temperature window of β-In2Se3. It is suggeted that the observed γ-to-β phase transition triggered by quite a low annealing temperature should be a rather lowered phase transition barrier of the epitaxy-stabilized In2Se3 thin-film system at a state far from thermodynamic equilibrium.
Pulling force of acoustic-vortex beams on centered elastic spheres based on the annular transducer model*
Authors: Li Yuzhi , Wang Qingdong , Guo Gepu , Chu Hongyan , Ma Qingyu , Tu Juan , Zhang Dong
Published: March 2020

To solve the difficulty of generating an ideal Bessel beam, an simplified annular transducer model is proposed to study the axial acoustic radiation force (ARF) and the corresponding negative ARF (pulling force) exerted on centered elastic spheres for acoustic-vortex (AV) beams of arbitrary orders. Based on the theory of acoustic scattering, the axial distributions of the velocity potential and the ARF for AV beams of different orders generated by the annular transducers with different physical sizes are simulated. It is proved that the pulling force can be generated by AV beams of arbitrary orders with multiple axial regions. The pulling force is more likely to exert on the sphere with a smaller k
0
a (product of the wave number and the radius) for the AV beam with a bigger topological charge due to the strengthened off-axis acoustic scattering. The pulling force decreases with the increase of the axial distance for the sphere with a bigger k
0
a. More pulling force areas with wider axial regions can be formed by AV beams using a bigger-sized annular transducer. The theoretical results demonstrate the feasibility of generating the pulling force along the axes of AV beams using the experimentally applicable circular array of planar transducers, and suggest application potentials for multi-position stable object manipulations in biomedical engineering.
Energy transfer, luminescence properties, and thermal stability of color tunable barium pyrophosphate phosphors*
Authors: Xu Meng-Jiao , Li Su-Xia , Ji Chen-Chen , Luo Wan-Xia , Wang Lu-Xiang
Published: March 2020

A series of barium pyrophosphate Ba2P2O7 (BPO) phosphors doped with Ce3+ or Tb3+ ions is synthesized via a co-precipitation method under reducing atmosphere. The phase structures, photoluminescence (PL) properties, and thermal stabilities of the samples are characterized by using powder x-ray diffraction (PXRD) and PL spectra. The emission colors of samples can be tuned from blue (0.1544, 0.0310) to green (0.2302, 0.4229) by changing the doping concentrations of Tb3+ under ultraviolet excitation. The energy transfer mechanism between Ce3+ and Tb3+ in the BPO is dipole–dipole interaction with a critical distance of 25.86 Å and an energy transfer efficiency of about 85%, which are determined through the PL spectrum and the decay curve. Moreover, the Ce3+/Tb3+ co-doped sample has good thermal stability for temperature quenching, and the emission intensity at 423 K is maintained at 95% measured at 298 K. The above results show that the BPO:Ce3+, Tb3+ can serve as a promising candidate of green emitting phosphor for solid-state lighting.
Gravitational waves induced by scalar perturbations during a gradual transition from an early matter era to the radiation era
Authors: Inomata Keisuke , Kohri Kazunori , Nakama Tomohiro , Terada Takahiro
Published: March 2020

We revisit the effects of an early matter dominated era on gravitational waves induced by the scalar perturbations. In this work, we consider the gradual transition from an early matter dominated era to the radiation dominated era, where the time scale of the transition is comparable to the Hubble time at that time. The gradual transition can be realized by the standard perturbative reheating with a constant decay rate. We carefully take into account the evolutions of the perturbations during the gradual transition for the first time. As a result, we find that the induced gravitational waves can be suppressed contrary to the previous results.
Gravitational waves from phase transition in a QCD-like hidden sector
Authors: Aoki Mayumi , Kubo Jisuke
Published: March 2020

The gravitational wave (GW) background produced at the chiral phase transition in a conformal extension of the standard model is studied. We compute the bounce solution by the iteration method and find that the transition’s inverse duration β normalized to the Hubble parameter H is β/H ≳ 103 which implies that the sound wave period τsw as an active GW source is shorter than 1/H. Using the factor τ
sw
H as the reduction factor for the sound wave contribution to the total GW spectrum, we evaluate the signal-to-noise ratio for the future space-based GW interferometer experiments. In the optimistic case we find that the GW signal could be detected by Big Bang Observer.
Active-sterile neutrino oscillations in the early Universe with the complete mixing matrix
Authors: Pastor Sergio
Published: March 2020

In the framework of a 3+1 scheme with an additional inert state, we consider the thermalisation of sterile neutrinos in the early Universe taking into account the full 4 × 4 mixing matrix. The evolution of the neutrino energy distributions is found solving the momentum-dependent kinetic equations with full diagonal collision terms. The degree of thermalisation of the sterile state is shown in terms of the effective number of neutrinos, N
eff, and its dependence on the three additional mixing angles (θ
14, θ
24, θ
34) and on the squared mass difference ∆m
2
41 is discussed. Our results are relevant for fixing the contribution of a fourth light neutrino species to the cosmological energy density, whose value is very well constrained by the final Planck analysis. For the preferred region of active-sterile mixing parameters from short-baseline neutrino experiments, we find that the fourth state is fully thermalised (N
eff ≃ 4).
Dark matter distribution in the Galactic dwarf spheroidal galaxies
Authors: Hayashi Kohei , Matsumoto Shigeki , Ibe Masahiro , Ishigaki Mino N. , Sugai Hajime , Shun’Horigome ichi
Published: March 2020

The Galactic dwarf spheroidal (dSph) galaxies are excellent laboratories to shed light on fundamental properties of dark matter. In particular, the dSphs are promising targets for the indirect searches for particle dark matter. In order to set robust constraints on properties of dark matter particles, revealing dark matter distributions in these galaxies is of crucial importance. However, there are various non-negligible systematic uncertainties on the estimate of dark matter distributions in these galaxies. Therefore, it is necessary to address the development of dynamical models considering the effects of these systematic uncertainties. In this talk, we will introduce our constructed dynamical models taking into account these uncertainties and present the inferred dark matter profiles in the classical dSphs using their current kinematic data. In addition, as an intriguing result, we will show that some of dSphs favor cusped dark halo rather than cored one even considering a mass-anisotropy degeneracy. Using these dark matter profiles, we will revisit the core-cusp problem and discuss a possible link between the inner slope of their dark halos and the star formation history.
Axion Dark Matter Search with Interferometrie Gravitational Wave Detectors
Authors: Nagano Koji , Obata Ippei , Fujita Tomohiro , Michimura Yuta
Published: March 2020

Axion dark matter differentiates the phase velocities of the circular-polarized photons. In [Phys. Rev. Lett. 123, 111301 (2019)], we have proposed a scheme to measure the phase difference by using a linear optical cavity. If the scheme is applied to the Fabry-Perot arm of Advanced LIGO-like (Cosmic-Explorer-like) gravitational wave detector, the potential sensitivity to the axion-photon coupling constant, g
aγ, reaches g
aγ ≃ 8 × 10−13 GeV−1 (4 × 10−14 GeV−1) at the axion mass m ≃ 3 × 10−13 eV (2 × 10−15 eV) and remains at around this sensitivity for 3 orders of magnitude in mass. Furthermore, its sensitivity has a sharp peak reaching g
aγ ≃ 10−14 GeV−1 (8 × 10−17 GeV−1) at m = 1.563 × 10−10 eV (1.563 × 10−11 eV). This sensitivity can be achieved without loosing any sensitivity to gravitational waves.
Small scale direct dark matter search experiments
Authors: Cebrián Susana
Published: March 2020

Experiments based on noble liquids and solid state cryogenic detectors have had a leading role in the direct detection of dark matter. But smaller scale projects can help to explore the new dark matter landscape with advanced, ultra-sensitive detectors based on recently developed technologies. Here, the physics case of different types of small scale dark matter experiments will be presented and many of them will be reviewed, highlighting the detection techniques and summarizing their properties, results and status.
Development of a Dark Matter Detector that Uses Liquid He and Field Ionization
Authors: Osterman D , Maris H , Seidel G , Stein D
Published: March 2020

We describe a new detector capable of directly measuring dark matter particles with masses as low as 1 MeV/c
2. The detector is based on the quantum evaporation of helium atoms from the surface of liquid helium and their detection using field ionization. When a dark matter particle collides with an atom in liquid helium, the deposited energy results in the evaporation of helium atoms from the liquid surface. A dense array of sharp, positively charged metal tips, known as the field ionization detector array, creates a strong electric field that ionizes the helium atoms and accelerates them into a calorimeter, which detects the impact. We studied field ionization from single tips and investigated the dependence of the ionization rate on the applied voltage. We discuss the results of these single tip field ionization experiments, as well as upcoming experiments, which will focus on studying the temperature dependence of field ionization of gaseous helium at low temperatures.
CALET results after three years on the International Space Station
Authors: Asaoka Y , Adriani O , Akaike Y , Asano K , Bagliesi M G , Berti E , Bigongiari G , Binns W R , Bonechi S , Bongi M , Bruno A , Buckley J H , Cannady N , Castellini G , Checchia C , Cherry M L , Collazuol G , Di Felice V , Ebisawa K , Fuke H , Guzik T G , Hams T , Hibino K , Ichimura M , Ioka K , Ishizaki W , Israel M H , Kasahara K , Kataoka J , Kataoka R , Katayose Y , Kato C , Kawanaka N , Kawakubo Y , Kohri K , Krawczynski H S , Krizmanic J F , Link J , Maestro P , Marrocchesi P S , Messineo A M , Mitchell J W , Miyake S , Moiseev A A , Mori M , Mori N , Motz H M , Munakata K , Nakahira S , Nishimura J , de Nolfo G A , Okuno S , Opsina N , Ormes J F , Ozawa S , Pacini L , Palma F , Pal’shin V , Papini P , Rauch B F , Ricciarini S B , Sakai K , Sakamoto T , Sasaki M , Shimizu Y , Shiomi A , Sparvoli R , Spillantini P , Stolzi F , Sugita S , Suh J E , Sulaj A , Takahashi I , Takita M , Tamura T , Terasawa T , Torii S , Tsunesada Y , Uchihori Y , Vannuccini E , Wefel J P , Yamaoka K , Yanagita S , Yoshida A , Yoshida K
Published: March 2020

The CALET (CALorimetric Electron Telescope) space experiment, which is currently conducting direct cosmic-ray observations onboard the International Space Station (ISS), is an all-calorimetric instrument optimized for cosmic-ray electron measurements with capability to measure hadrons and gamma-rays. Since the start of observation in October 2015, smooth and continuous operations have taken place. In this paper, we will give a brief summary of the CALET observations ranging from charged cosmic rays, gamma-rays, to space weather, while focusing on the energy spectra of electrons and protons.
A new high energy gamma-ray observatory in the southern hemisphere: The ALPACA experiment
Authors: Calle C. , Hibino K. , Hotta N. , Katayose Y. , Kato C. , Kato S. , Kawata K. , Kihara W. , Ko Y. , Kojima H. , Mayta R. , Miranda P. , Mitsui H. , Munakata K. , Nakada H. , Nakamura Y. , Nishizawa M. , Ogio S. , Ohnishi M. , Ohura T. , Oshima A. , Raljevich M. , Rivera H. , Saito T. , Sako T. , Sako T. K. , Sengoku Y. , Shibata S. , Shiomi A. , Subieta M. , Tajima N. , Takano W. , Takita M. , Tameda Y. , Tanaka K. , Tsuchiya H. , Tsunesada Y. , Udo S. , Yagisawa K. , Yokoe Y.
Published: March 2020

The ALPACA experiment is a new international project between Bolivia and Japan. It is going to consist of an 83,000 m2 surface air-shower array and a 5,400 m2 underground water Cherenkov muon detector array, and the experimental site is at Mt. Chacaltaya plateau at an altitude of 4,740 m. Its main target is to observe 100 TeV gamma rays and explore high-energy gamma-ray sources in the southern sky. This is because such high-energy gamma rays hold the key to identify the origin of cosmic rays at the knee region of the energy spectrum. So far many high-energy gamma-ray sources have been found in the southern sky. They are emitting gamma rays of several tens of TeV, so some of them could be PeVatrons which accelerate cosmic rays to PeV energy region in the Galaxy. By observing them in higher energy region, we will obtain new knowledge of cosmic-ray acceleration to the knee region, and discover new gamma-ray sources. As the prototype experiment of ALPACA, the ALPAQUITA experiment is now under construction. In a MC simulation, we found that ALPAQUITA has the ability of detecting bright gamma-ray sources in the southern hemisphere such as Vela X within 1 year.
Cygnus X-3 at very high energies
Authors: Sinitsyna V.G. , Sinitsyna V.Y.
Published: March 2020

Cyg X-3 is a well-known binary system which also belongs to a microquasar-type objects. It is actively studied through the wide range of electromagnetic spectrum including ultrahigh energies. Here, we present the results of more than 20-year-long studies of Cyg X-3 in the range of 800 GeV-100 TeV with the SHALON telescope. The detected TeV γ-ray source was identified with Cyg X-s based on the detection of the γ-ray flux modulation at the orbital period of this binary system of 4.8 hours. Detected modulation of TeV γ-ray emission with orbit together with the high luminosity of the companion star of Cyg X-3 and the close orbit leads to an efficient generation of the part of γ-ray emission in the inverse Compton scattering. The correlation of TeV flux increases with the flaring activity of Cyg X-3 at X-ray and radio ranges is found which could be associated with powerful mass ejections from the central regions around the black hole.
Multi-messenger astronomy with very-high-energy gamma-ray observations
Authors: Hinton Jim , Ruiz-Velasco Edna
Published: March 2020

After decades of development, multi-messenger astronomy, the combination of information on cosmic sources from photons, neutrinos, charged particles and gravitational waves, is now an established reality. Within this emerging discipline we argue that very-high-energy gamma-ray observations play a special role. We discuss the recent progress on explosive transients, the connections between neutrino and gamma-ray astronomy, and the search for dark matter. Finally, the experimental prospects for the next decade in the VHE gamma-ray field are summarised.
Extreme Energy Events: an extended multi purpose cosmic ray observatory
Authors: Gnesi I. , Abbrescia M. , Avanzini C. , Baldini L. , Baldini Ferroli R. , Batignani L. G. , Battaglieri M. , Boi S. , Bossini E. , Carnesecchi F. , Cicalo C. , Cifarelli L. , Coccetti F. , Coccia E. , Corvaglia A. , De Gruttola D. , De Pasquale S. , Fabbri L. , Galante L. , Galeotti P. , Garbini M. , Gemme G. , Grazzi S. , Hatzifotiadou D. , La Rocca P. , Liu Z. , Mandaglio G. , Maron G. , Mazziotta M. N. , Mulliri A. , Nania R. , Noferini F. , Nozzoli F. , Palmonari F. , Panareo M. , Panetta M. P. , Paoletti R. , Pellegrino C. , Perasso L. , Pinto C. , Piragino G. , Pisano S. , Riggi F. , Righini G. C. , Ripoli C. , Rizzi M. , Sartorelli G. , Scapparone E. , Schioppa M. , Scribano A. , Selvi M. , Serri G. , Squarcia S. , Taiuti M. , Terreni G. , Trifir A. , Trimarchi M. , Vistoli M. C. , Votano L. , Williams M. C. S. , Zichichi A. , Zuyeuski R.
Published: March 2020

EEE is an extended cosmic ray observatory, covering more than 10 degrees in latitude and longitude. The relative distances between clusters of telescopes reached the 1200 km, allowing the search for rare long distance correlations between cosmic showers. On the other side each EEE telescope is capable of measuring the flux of secondary particles, opening to the study of low energy phenomena such as solar activity and Forbush decreases. An introduction to the observaotry and updates on the main scientific results are presented. Last updates on the searches for rare correlated showers, with a set of long distance correlation candidate events are also reported.
Coherent Elastic Neutrino-Nucleus Scattering
Authors: Scholberg Kate
Published: March 2020

Coherent elastic neutrino-nucleus scattering (CEvNS), the gentlest kind of interaction of a neutrino with an entire nucleus, was first predicted in 1974, but not observed until 2017 by the COHERENT collaboration. COHERENT and many other experiments are pursuing further measurements of this low momentum transfer process. We review the physics motivations for these measurements and prospects and status of current and future CEvNS experiments.
Neutrinoless double beta decay theory
Authors: Šimkovic F
Published: March 2020

Within left-right symmetric model a generalization of the Majorana neutrino mass for the case of light and and heavy neutrinos is introduced and analyzed. Further, current status of calculation of the neutrinoless double beta decay matrix elements is shortly reviewed. An important connection between them and matrix element of double Gamow-Teller operator is established. A new way of fixing quenching of axial-vector coupling constant gA
is presented.
The effects of coherent neutrino mixing modulation by dark matter.
Authors: Marks W S
Published: March 2020

If there was a coupling between neutrinos and Dark Matter, then there could be an induced modulation of the neutrino-mixing spectrum analogous to the one produced by the MSW effect. The possible results of such a modulation have previously been investigated for the case where coherent effects cannot be isolated and the resulting pattern is de-coherent. This presentation is on an investigation that included coherent effects, which are relevant for very high-energy neutrinos as the wave-packets remain coherent over cosmological distances. The investigation found that observable coherent effects are produced by potentials several orders of magnitude smaller than the minimum potential required to produce an observable de-coherent effect, with the amount being baseline dependent. This extends the range of observability down to levels where an interaction is likely to exist, if it exists at all. The significant challenges in making such an observation will be covered.
Neutrino Oscillation Experiments
Authors: Tanaka Hirohisa A.
Published: March 2020

Accelerator- and reactor-based experiments operating at the first maximum for atmospheric oscillation have been an important driver in our understanding of neutrino properties in recent years. The current generation of reactor-based experiments have measured the mixing angle θ
13 with great precision, while accelerator-based experiments have taken significant exposures with both vμ
and

v
¯

μ

beams to study their disappearance into other flavors, primarily sensitive to the mixing angle θ
23, and electron neutrinos appearing via vμ
→ ve
and

v
¯

μ

→

v
¯

e

oscillations which are sensitive to the ordering of the neutrino mass eigenvalues and the CP-violating phase δCP
. Both reactor- and accelerator-based experiments have measured the mass-splitting

Δ

m

a
t
m

2

to great precision.

This presentation covers the latest developments in neutrino oscillation experiments in the context of the standard three flavor paradigm. Other presentations in the session provided a theoretical overview [1] and covered short baseline experiments exploring large neutrino mass splittings and other phenomenon driven by physics beyond the three flavor paradigm [2], solar neutrinos [3], geoneutrinos, and supernova neutrinos [4].
Jinping Neutrino Experiment: a Status Report
Authors: Xu Benda
Published: March 2020

A large liquid scintillator detector is being discussed and actively developed in China JinPing underground Laboratory. We envision a 5kt detector at 7000-water-meter-equivalent overburden to target terrestrial, solar and supernovae neutrinos. A 1t prototype detector has been installed on-site in 2017. Liquid scintillator performance, radioactive and cosmogenic backgrounds, simulation and analysis pipelines have been carefully investigated. We report the status of the Jinping Neutrino Experiment project and milestones of R&D studies.
Study and experiment on the alternative technique of frequency–dependent squeezing generation with EPR entanglement for Virgo
Authors: Bawaj M , Barsuglia M , Bazzan M , Calloni E , Ciani G , Conti L , D’Angelo B , De Laurentis M , De Rosa R , Di Pace S , Fafone V , Garaventa B , Gemme G , Gennai A , Giacoppo L , Harms J , Khan I , Majorana E , Naticchioni L , Nguyen C , Passuello D , Prodi G , Ricci F , Rocchi A , Sequino V , Sorrentino F , Vardaro M , Zendri JP
Published: March 2020

In this paper, we summarize the present state-of-the-art on the proof-of-principle experiment of frequency-dependent squeezing implemented through EPR entanglement for Virgo gravitational-wave detector and we introduce Virgo subsystem proposal for frequency-dependent squeezing, obtained with a compact apparatus and without the costs required by the infrastructure for the filter cavity.
A nonparametric method to evaluate significance of events in search for gravitational waves with false discovery rate
Authors: Yuzurihara Hirotaka , Mano Shuhei , Tagoshi Hideyuki
Published: March 2020

During recent observation runs by LIGO and Virgo, tens of gravitational wave events have been observed. The gravitational wave network of LIGO/Virgo/KAGRA is planning longer observation runs with improved sensitivity in the future. In this situation, it is important to evaluate the significance of each event with reliable methods since we expect, as the observation period becomes longer and as the sensitivity of the detector improves, we expect to detect more false positive events with a given threshold for the false alarm rate. In this paper, we introduceq-valuewhich was first introduced by Storey[1], and is interpreted as False Discovery Rate (FDR). We introduce an algorithm to evaluate FDR in a non-parametric way, and apply it to publically available results of the analysis of the advanced LIGO O1 data, and find that we can obtain a better significance for GW151012 which has the lowest significance in the O1 events. For other events, we obtain consistent results already obtained by LIGO and Virgo.
The search for Majorana neutrinos with a background-free gaseous Xenon TPC at the tonne scale
Authors: Monrabal F.
Published: March 2020

The next generation of neutrinoless double beta decay search experiments aims to reach sensitivities to this half-life of the process up to 1028 years. This will require tonne scale detectors with almost no background in their region of interest, which represents a large improvement with respect to current technologies. With this scenario, the NEXT collaboration presents two parallel developments: NEXT-High Definition and NEXT-Barium atOm Light Detection. The first is based on the incremental improvement of the current pressure gas xenon technology, and the second is based on the use of a barium tagging technology.
Measurement of ambient neutrons in an underground laboratory at Kamioka Observatory and future plan
Authors: Mizukoshi Keita , Taishaku Ryosuke , Hosokawa Keishi , Kobayashi Kazuyoshi , Miuchi Kentaro , Naka Tatsuhiro , Takeda Atsushi , Tanaka Masashi , Wada Yoshiki , Yorita Kohei , Yoshida Sei
Published: March 2020

Ambient neutrons are one of the most serious backgrounds for underground experiments in search of rare events. The ambient neutron flux in an underground laboratory of Kamioka Observatory was measured using a 3He proportional counter with various moderator setups. Since the detector response largely depends on the spectral shape, the energy spectra of the neutrons transported from the rock to the laboratory were estimated by Monte-Carlo simulations. The ratio of the thermal neutron flux to the total neutron flux was found to depend on the thermalizing efficiency of the rock. Thus, the ratio of the count rate without a moderator to that with a moderator was used to determine this parameter. Consequently, the most-likely neutron spectrum predicted by the simulations for the parameters determined by the experimental results was obtained. The result suggests an interesting spectral shape, which has not been indicated in previous studies. The total ambient neutron flux is

(
23.5
±

0.7

stat
.

−
2.1

+
1.9

sys
.

)
×

10

−
6

cm

−
2

s

−
1

[1]. In this paper, we explain our method of the result and discuss our future plan.
How using comics can assist in determining the students’ learning of distance-time graphs
Authors: Azamain M S , Shahrill M , Musa N K H , Batrisyia I
Published: March 2020

The art of teaching mathematics at all levels requires a lot of creativity and innovation from a teacher for the students to effectively grasp what they are taught. Teachers tend to devise various means always ensure that they understand the attention of a learner in mathematics lessons bearing in mind that some learners easily switch off in mathematics lessons. In this study, we explored how a teacher can effectively use comics while teaching upper secondary students the topic of Distance-Time Graphs. The research entails that problems exists among the mathematics areas where the students face a challenge in grasping the concepts they are taught and even lose concentration more quickly while the teacher is teaching thereby falsely conceptualising that mathematics is a difficult subject. The concepts involved in this paper are in concurrent to the existing literature that the use of comics is one of the ways to draw the attention of students while teaching them. An action research approach was adopted to determine whether students’ understanding of mathematics concepts in Brunei schools could be improved using comics. The problems that 38 Year 10 students encountered while learning Distance-Time Graphs have also been elaborated in this paper, and the methodology through which comics can be incorporated into the teaching and learning process in this area has also be shown for practical application in the Brunei secondary school. There is also an elaboration on how the research concerning the use of comics in teaching was conducted and how the hypothesis was analyzed and evaluated to have a positive outcome in the teaching and learning process.
Developing a hypothetical learning trajectory of fraction based on RME for junior high school
Authors: Yulia Y , Musdi E , Afriadi J , Wahyuni I
Published: March 2020

Preliminary research showed the learning trajectory of fraction in the school that could not facilitate students to reinvent fraction concepts. Therefore, this research aimed to produce a hypothetical learning trajectory (HLT) for teaching fraction using realistic mathematics education (RME). The HLT was developed with a design research that consisted of a cyclic process of preparing for the experiment, conducting classroom experiment, and performing retrospective analysis. This study involved 25 students SMPN 1 Timpeh, Indonesia. Data were collected through student activity sheets, videotaping, field notes, and interviews. The data analysis technique used descriptive analysis techniques. The result showed HLT for teaching fraction using RME that could be help all of levels students. This HLT helped students to reinvent fraction concepts through horizontal and vertical mathematical processes. Finally, the HLT facilitated students to make their own models from informal to formal and improved the interactions between students and teachers.