Practical use of reactor anti-neutrinos for nuclear safeguard in Vietnam

One of the most abundant man-made sources of low energy (few~MeVs) neutrinos, reactor neutrino, is not only useful for studying neutrino properties, but it is also used in practical applications. In this study, we investigate the practical use of reactor neutrino detectors for nuclear safeguard in Vietnam, specifically at the Dalat Nuclear Reactor, a future research facility, and presumably commercial reactors with 500~kW, 10~MW, and 1000~MW thermal powers, respectively. We compute the rate of observed inverted beta decay events, as well as the statistical significance of extracting isotope composition under the practical assumptions of detector mass, detection efficiency, and background level. We find that a 1-ton detector mass can allow us to detect the reactor's on-off transition state from a few hours to a few days, depending on the standoff distance and reactor thermal power. We investigate how background and energy resolution affect the precision of the extracted weapon-usable ${}^{239}\text{Pu}$ isotope. We conclude that in order to distinguish the 10\% variation of the ${}^{239}\text{Pu}$ in the 10~MW thermal power reactor, a 1-ton detector placed 50~m away must achieve 1\% background level. Increasing the statistics by using a 10x larger detector or placing it $\sqrt{10}$ times closer to the reactor alleviates the requirement of the background level to 10\%

Stringent constraint on CPT violation with the synergy of T2K-II, NOν\nuA extension, and JUNO

Neutrino oscillation experiments have measured precisely the mass-squared differences of three neutrino mass eigenstates, and three leptonic mixing angles by utilizing both neutrino and anti-neutrino oscillations. The possible CPT violation may manifest itself in the difference of neutrino and anti-neutrino oscillation parameters, making these experiments promising tools for testing CPT invariance. We investigate empirically the sensitivity of the CPT test via the difference in mass-squared splittings ($\Delta m^2_{31} - \Delta \overline{m}^2_{31}$) and in leptonic mixing angles ($\sin^2\theta_{23} - \sin^2\overline{\theta}_{23}$) with the synergy of T2K-II, NO$\nu$A extension, and JUNO experiments. If the CPT symmetry is found to be conserved, the joint analysis of the three experiments will be able to establish limits of $|\Delta m^2_{31} - \Delta \overline{m}^2_{31}|$ < $5.3\times 10^{-3} \text{eV}^2$ and $|\sin^2\theta_{23} - \sin^2\overline{\theta}_{23}|$ < $0.10$ at 3$\sigma$ C. L. on the possible CPT violation. We find that with ($\Delta m^2_{31} - \Delta \overline{m}^2_{31}$), the dependence of the statistical significance on the relevant parameters to exclude the CPT conservation is marginal, and that, if the difference in the best-fit values of $\Delta m^2_{31}$ and $\Delta \overline{m}^2_{31}$ measured by MINOS(+) and NO$\nu$A persists as the true, the combined analysis will rule out the CPT conservation at 4$\sigma$ C. L.. With the ($\sin^2\theta_{23} - \sin^2\overline{\theta}_{23}$), the statistical significance to exclude CPT invariance depends strongly on the true value of $\theta_{23}(\overline{\theta}_{23})$. In case of maximal mixing of $\theta_{23}$, the CPT conservation will be excluded at 3$\sigma$ C. L. or more if the difference in the best-fit values of $\theta_{23}$ and $\overline{\theta}_{23}$ remains as the true.Comment: 10 pages, 10 figure

Hamiltonian dynamics and spectral theory for spin-oscillators

We study the Hamiltonian dynamics and spectral theory of spin-oscillators. Because of their rich structure, spin-oscillators display fairly general properties of integrable systems with two degrees of freedom. Spin-oscillators have infinitely many transversally elliptic singularities, exactly one elliptic-elliptic singularity and one focus-focus singularity. The most interesting dynamical features of integrable systems, and in particular of spin-oscillators, are encoded in their singularities. In the first part of the paper we study the symplectic dynamics around the focus-focus singularity. In the second part of the paper we quantize the coupled spin-oscillators systems and study their spectral theory. The paper combines techniques from semiclassical analysis with differential geometric methods.Comment: 32 page

SU(3)_LxU(1)_N Model for Right-Handed Neutrino Neutral Currents

A model based on the \mbox{SU(3)}_L\otimes \mbox{U(1)}_N gauge group, in which neutrinos have right-handed neutral currents is considered. We argue that in order to have a result consistent with low-energy one, the right-handed neutrino component must be treated as correction instead of an equivalent spin state.Comment: 6 pages, Latex, no figures, Accepted for publication in Phys. Rev.

Required flows for aquatic ecosystems in Ma River, Vietnam

Ecological flow requirements for the Ma River in dry season were assessed in three reaches of Ma – Buoi, Ma – Len and Ma – Chu. 5 indictor fish species was chosen based on biodiversity survey and roles of those species in aquatic ecosystem as well as local communities. Biological and hydrological data (dry season of 2016- 2017) and 35 year recorded hydrological data were collected and analyzed as input data for a physical habitat model River HYdraulic and HABitat SImulation Model – RHYHABSIM. Model results shown that the optimal flows of the reaches were very much higher compare with the minimum annual low flow - MALF. In this study, MALF7day were applied to calculate the recommended minimum flows of the three reaches. The recommended required minimum flows for Ma – Buoi, Ma – Len and Ma – Chu reaches were 51 m3/s, 49 m3/s and 61 m3/s, respectively. It must be stressed that this study only assessed whether or not there is enough habitat available for the river to sustain a healthy ecosystem

Petrographic Characteristics and Depositional Environment Evolution of Middle Miocene Sediments in the Thien Ung - Mang Cau Structure of Nam Con Son Basin

This paper introduces the petrographic characteristics and depositional environment of Middle Miocene rocks of the Thien Ung - Mang Cau structure in the central area of Nam Con Son Basin based on the results of analyzing thin sections and structural characteristics of core samples. Middle Miocene sedimentary rocks in the studied area can be divided into three groups: (1) Group of terrigenous rocks comprising greywacke sandstone, arkosic sandstone, lithic-quartz sandstone, greywacke-lithic sandstone, oligomictic siltstone, and bitumenous claystone; (2) Group of carbonate rocks comprising dolomitic limestone and bituminous limestone; (3) Mixed group comprising calcareous sandstone, calcarinate sandstone, arenaceous limestone, calcareous claystone, calcareous silty claystone, dolomitic limestone containing silt, and bitumen. The depositional environment is expressed through petrographic characteristics and structure of the sedimentary rocks in core samples. The greywacke and arkosic sandstones are of medium grain size, poor sorting and roundness, and siliceous cement characterizing the alluvial and estuarine fan environment expressed by massive structure of core samples. The mixed calcareous limestone, arenaceous dolomitic limestone, and calcareous and bituminous clayey siltstone in the core samples are of turbulent flow structure characterizing shallow bay environment with the action of bottom currents. The dolomitic limestones are of relatively homogeneous, of microgranular and fine-granular texture, precipitated in a weakly reducing, semi-closed, and relatively calm bay environment

Accumulation and distribution of zinc in the leaves and roots of the hyperaccumulator Noccaea caerulescens

Understanding the uptake mechanisms of heavy metals by hyperaccumulators is necessary for improving phytoextraction options to reduce metal toxicities in contaminated soils. In this study, the capacity of Zn uptake by the hyperaccumulator Noccaea caerulescens was investigated and compared to the non-hyperaccumulator Thlaspi arvense. The plants were grown under hydroponic conditions in a glasshouse. The distribution of Zn in the roots and leaves of these species was investigated by scanning electron microscopy with energy-dispersive X-ray analysis. Compared with the control with no Zn added, it was shown that prolonged Zn treatments decreased the biomass of both N. caerulescens and T. arvense. Since N. caerulescens requires Zn for growth, no Zn toxicity symptoms were observed, even when the Zn concentration in shoots reached 2.5% dry mass. T. arvense showed serious Zn toxicity only after two weeks of Zn treatment. Zn uptake by N. caerulescens was mainly translocated to the leaves while almost all of the Zn taken-up by T. arvense was retained in the roots. In N. caerulescens, increasing concentration of Zn in the supply decreased Ca and P concentrations in the shoots by up to 50 and 35%, respectively. Zn-containing crystals were abundant in both the upper and lower epidermal cells of the leaves and in the cortex of the roots during the later growth phase. Co-localization of Ca and Zn, P and S were found in leaf and root tissues. The results suggest that Zn-rich crystals with an abundance of the Zn ligand in the roots and shoots, and co-localization and interaction between Zn and other ions, may have functional significance with respect to conferring particular attributes to N. caerulescens that are not present in the non-hyperaccumulator counterpart. An understanding of these species-specific differences has relevance from the perspective of offering some insight into how particular species could contribute to a strategy for the detoxification of Zn-contaminated sites