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[en] Polonium is rapidly emerging as an international environmental health concern primarily because of the recent rise in hydraulic fracturing (fracking). Recovery of unconventional oil and gas generates produced water containing natural radioactivity, which is increasing the radiological impact of 210Po. In this context, accurate measurements of 210Po in environmental samples is crucial because 210Po is the main contributor to the natural radiation dose received by all living organisms. However, the analytical chemistry of polonium is complicated, primarily due to its volatility. This review highlights recent analytical progress and challenges in determination of 210Po in the environmental and biological samples. (author)
[en] Through C+Au collisions at = 200GeV using a multiphase transport (AMPT) model, the azimuthal angle dependences of the Hanbury Brown-Twiss (HBT) radii relative to the second- and third-order participant plane from π-π correlations are discussed. Three initial geometric configurations of C, namely three--cluster triangle, three--cluster chain and Woods-Saxon distribution of nucleons, are taken into account, and their effects on the correlations are investigated. The ratio of the third- to the second-order HBT radii R/R is shown to be a clear probe for three configurations. In addition, this work presents the hadronic rescattering time evolution of the azimuthally dependent HBT radii. From the present study, one can learn that the HBT correlation from identical particles at freeze-out is able to provide the information of different initial configurations as collective flow proposed before.
[en] In this paper, the embedded-atom method was used to study the influence of different solute elements (Co,Cu,Yb) on the thermophysical properties of liquid Ni-based alloys. By exploring the relationship between surface tension, viscosity, diffusion coefficient and temperature of liquid Ni-based alloys with three solutes in the range of 1500~1900 K, we found that under certain components the surface tension of liquid Ni-based alloys with three solutes decreased as temperature increased. Except the case that the atomic radius of the same period decreased with the increase of the atomic number and influence of lanthanide and actinide contraction, the surface tension of liquid Ni-based alloys decreased with the increase of atomic number. The viscosity of liquid alloy showed a downward trend with increasing temperature, and the viscosity decreased exponentially with the temperature increasing under certain components. The variation trend of diffusion coefficient of the three kinds of atoms was similar to that of the temperature, which increased with the increase of temperature under the same component. Especially, the diffusion coefficient increases exponentially with the increase of temperature under certain components. These simulated data provided necessary thermophysical parameters for non-equilibrium dynamics analysis of liquid-phase alloys and also supplied a sound theoretical basis for exploring the internal physical mechanism of "liquid microstructures–thermophysical properties–preferred phase of nucleation".
[en] The azimuthal anisotropy of charged particles produced in =8.16 TeV p+Pb collisions is measured with the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 165 nb that was collected in 2016. Azimuthal anisotropy coefficients, elliptic and triangular , extracted using two-particle correlations with a non-flow template fit procedure, are presented as a function of particle transverse momentum (p) between 0.5 and 50 GeV. The results are also reported as a function of centrality in three different particle p intervals. The results are reported from minimum-bias events and jet-triggered events, where two jet p thresholds are used. The anisotropies for particles with p less than about 2 GeV are consistent with hydrodynamic flow expectations, while the significant non-zero anisotropies for p in the range 9–50 GeV are not explained within current theoretical frameworks. In the p range 2–9 GeV, the anisotropies are larger in minimum-bias than in jet-triggered events. Possible origins of these effects, such as the changing admixture of particles from hard scattering and the underlying event, are discussed.
[en] This article comments how experts in metallurgy and non destructive testing discussed whether welds of main steam pipes of the Flamanville EPR had to be made redone after many non-compliancies were noticed. It recalls how this issue emerged in 2017 and has been processed. This fault appeared to be due to the choice of the filler metal. As these pipes are classified 'failure excluded', a very rigorous approach had to be adopted which resulted in decisions by EDF while informing the ASN. The IRSN provided three full-time experts in metallurgy and ultrasound controls. These controls revealed a bad execution of some of the welds. The IRSN wanted all the welds to be redone. Technical solutions are thus still to be proposed which will be analysed by the IRSN
[en] We observed a nucleus consist of a K- meson and two protons, 'K-pp', at the J-PARC. The binding energy is as large as ∼50 MeV, which is about 10 times larger than the standard nuclear binding energy, and the width is ∼100 MeV. The momentum transfer analysis is indicating that the size of 'K-pp' could be as small as ∼0.5 fm. The results will provide new insights on the origin of hadron mass and the physics at the very high density matter, such as a core of neutron stars. (author)
[en] We use the method of light-cone sum rules to study decay properties of P-wave bottom baryons belonging to the SU(3) flavor 6 representation. In Cui et al. (Phys Rev D 99:094021, 2019) we have studied their mass spectrum and pionic decays, and found that the Σ(6097) and Ξ(6227) can be well interpreted as P-wave bottom baryons of J=3/2. In this paper we further study their decays into ground-state bottom baryons and vector mesons. We propose to search for a new state Ξ(5/2), that is the J=5/2 partner state of the Ξ(6227), in the Ξ(5/2)→Ξρ→Ξππ decay process. Its mass is 12±5 MeV larger than that of the Ξ(6227).
[en] We analyse the validity of a commonly used identification between structures of the virtual photon γ→ and vector meson V→ transitions. In the existing studies of S-wave vector-meson photoproduction in the literature, such an identification is typically performed in the light-front (LF) frame while the radial component of the meson wave function is rather postulated than computed from the first principles. The massive photon-like V→ vertex, besides the S-wave component, also contains an extra D-wave admixture in the rest frame. However, the relative weight of these contributions cannot be justified by any reasonable nonrelativistic potential model. In this work, we investigate the relative role of the D-wave contribution starting from the photon-like quarkonium V→ transition in both frames: in the rest frame (with subsequent Melosh spin transform to the LF frame) and in the LF frame (without Melosh transform). In both cases, we employ the same radial wave functions found in the potential approach. We show that the photon-like transition imposed in the rest frame, with subsequent boosting to the LF frame, leads to significant discrepancies with the experimental data. In the second case, i.e. imposing the photon-like transition straight in the LF frame, we find that the corresponding total J/ψ(1S) photoproduction cross sections are very close to those obtained with the "S-wave only" V→ transition, both leading to a good description of the data. However, we find that the "S-wave only" transition leads to a better description of photoproduction data for excited (e.g. ψ′(2S)) heavy quarkonium states, which represent a more effective tool for study of D-wave effects. Consequently, the predictions for production of excited states based on the photon-like structure of V→ transition should be treated with a great care due to a much stronger sensitivity of the D-wave contribution to the nodal structure of quarkonium wave functions.
[en] We estimate the future sensitivity of the high luminosity (HL-) and high energy (HE-) modes of the Large Hadron Collider (LHC) and of a 100 TeV future circular collider (FCC-hh) to leptoquark (LQ) pair production in the muon-plus-jet decay mode of each LQ. Such LQs are motivated by the fact that they provide an explanation for the neutral current B-anomalies. For each future collider, Standard Model (SM) backgrounds and detector effects are simulated. From these, sensitivities of each collider are found. Our measures of sensitivity are based upon a Run II ATLAS search, which we also use for validation. We illustrate with a narrow scalar ('S3') LQ and find that, in our channel, the HL-LHC has exclusion sensitivity to LQ masses up to 1.8 TeV, the HE-LHC up to 4.8 TeV and the FCC-hh up to 13.5 TeV.
[en] Topological insulators (TIs) a new quantum state of matter predicted to have an interesting surface properties. In this report, we study the surface properties of BiTeSe (BTS) topological insulators thin films. Raman measurements on BTS thin film show a strong intensity of A (∼62 cm), E (∼123 cm) and A (∼170 cm) modes in addition to A (∼140 cm) modes. Elemental analyses were done using X-ray photoelectron spectroscopy (XPS). Resistance versus temperature measurement reveal a magnetic field-driven metallic behavior at high temperatures and further analysis on magnetic measurement shows a diamagnetic nature of BTS film. The magneto-resistance measurements on these films exhibit a weak antilocalization effect that arises due to quantum interfering nature of topological insulators and the measured weak anti-localization effect is fitted using Hikami–Larkin–Nagaoka (HLN) model.