105 research outputs found

    Sovereign Wealth Funds: Russian and International Experience

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    Taking the Russian and the International experience, the principal aim of this study is to analyse sovereign wealth funds critically. It remains well known that the Russian National Wealth Fund is vital in the macroeconomic policy of the Russian state. After the abolition of the Reserve Fund in 2018, the Russian National Wealth Fund has to solve a wide range of tasks. In this context, one can argue that the sovereign welfare fund is a specialised monetary fund used to stabilise the state budget when government revenues decline. The welfare fund is also used to finance government needs in the long-term period. The role of sovereign wealth funds is growing in the world. They accumulate large amounts of financial resources. Sovereign wealth funds are founded in such countries where the budget strongly depends on market factors. In most cases, these factors are global commodity prices. The funds’ money is used to cover the deficit of the relevant budget in case of unfavourable market shifts. In the period of high commodity prices, the fund accumulates an excess of export earnings. Against this backdrop, the key purpose of the study is to evaluate the efficiency of managing the National Wealth Fund in the Russian Federation. The study was carried out using the methods of synthesis, analysis, economic analysis, as well as graphic methods, and the methods of comparisons and analogies, which in turn helps in evaluating the extent of efficiency of managing the Russian National Wealth Fund.. The research findings can be used when developing an investment strategy (investment portfolio) of the Russian National Wealth Fund, through which it can aim at balancing the insurance pension system, financing of the federal budget deficit, and co-financing of voluntary pension savings. In this regard, it is imperative for the fund to perform in productive investment activities

    Minigap, Parity Effect and Persistent Currents in SNS Nanorings

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    We have evaluated a proximity-induced minigap in the density of states (DOS) of SNS junctions and SNS nanorings at an arbitrary concentration of non-magnetic impurities. We have demonstrated that an isotropic energy minigap in the electron spectrum opens up already at arbitrarily weak disorder, while angle resolved DOS at higher energies can remain strongly anisotropic. The minigap value ϵg\epsilon_g can be tuned by passing a supercurrent through an SNS junction or by applying a magnetic flux Φ\Phi to an SNS ring. A non-monotonous dependence of ϵg\epsilon_g on Φ\Phi has been found at weak disorder. We have also studied persistent currents in isolated SNS nanorings. For odd number of electrons in the ring we have found a non-trivial current-phase (current-flux) relation which -- at relatively high disorder -- may lead to a π\pi-junction state and spontaneous currents in the ground state of the system.Comment: 7 pages, 8 figure

    Josephson current and Andreev states in superconductor-half metal-superconductor heterostructures

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    We develop a detailed microscopic theory describing dc Josephson effect and Andreev bound states in superconducting junctions with a half-metal. In such systems the supercurrent is caused by triplet pairing states emerging due to spin-flip scattering at the interfaces between superconducting electrodes and the half-metal. For sufficiently clean metals we provide a detailed non-perturbative description of the Josephson current at arbitrary transmissions and spin-flip scattering parameters for both interfaces. Our analysis demonstrates that the behavior of both the Josephson current and Andreev bound states crucially depends on the strength of spin-flip scattering showing a rich variety of features which can be tested in future experiments.Comment: 12 pages, 7 figures; version published in Phys. Rev.

    The 6^{6}H states studied in the d(8He,α)d(^8\text{He},\alpha) reaction and evidence of extremely correlated character of the 5^{5}H ground state

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    The extremely neutron-rich system 6^{6}H was studied in the direct 2H(8He,4He)6^2\text{H}(^8\text{He},{^4\text{He}})^{6}H transfer reaction with a 26 AA MeV secondary 8^{8}He beam. The measured missing mass spectrum shows a resonant state in 6^{6}H at 6.8(3)6.8(3) MeV relative to the 3^3H+3n3n threshold. The population cross section of the presumably pp-wave states in the energy range from 4 to 8 MeV is dσ/dΩc.m.190(40)d\sigma/d\Omega_{\text{c.m.}} \simeq 190(40) μ\mub/sr in the angular range 5<θc.m.<165^{\circ}<\theta_{\text{c.m.}}<16^{\circ}. The obtained missing mass spectrum is free of the 6^{6}H events below 3.5 MeV (dσ/dΩc.m.3d\sigma/d\Omega_{\text{c.m.}} \lesssim 3 μ\mub/sr in the same angular range). The steep rise of the 6^{6}H missing mass spectrum at 3 MeV allows to show that 4.5(3)4.5(3) MeV is the lower limit for the possible resonant state energy in 6^{6}H tolerated by our data. According to paring energy estimates, such a 4.5(3)4.5(3) MeV resonance is a realistic candidate for the 6^{6}H ground state (g.s.). The obtained results confirm that the decay mechanism of the 7^{7}H g.s.\ (located at 2.2 MeV above the 3^{3}H+4n4n threshold) is the ``true'' (or simultaneous) 4n4n emission. The resonance energy profiles and the momentum distributions of the sequential 6^{6}H \,\rightarrow \, ^5H(g.s.)+n\, \rightarrow \, ^3H+3n3n decay fragments were analyzed by the theoretically-updated direct four-body-decay and sequential-emission mechanisms. The measured momentum distributions of the 3^{3}H fragments in the 6^{6}H rest frame indicate very strong ``dineutron-type'' correlations in the 5^{5}H ground state decay.Comment: 9 pages, 11 figure

    Photodisintegration of 4^4He into p+t

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    The two-body photodisintegration of 4^4He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at Jefferson Laboratory. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid 4^4He target. This is the first measurement of the photodisintegration of 4^4He above 0.4 GeV. The differential cross sections for the γ\gamma4^4Hept\to pt reaction have been measured as a function of photon-beam energy and proton-scattering angle, and are compared with the latest model calculations by J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the calculations that include three-body mechanisms, thus confirming their importance. These results reinforce the conclusion of our previous study of the three-body breakup of 3^3He that demonstrated the great importance of three-body mechanisms in the energy region 0.5-0.8 GeV .Comment: 13 pages submitted in one tgz file containing 2 tex file and 22 postscrip figure

    An Extreme Precision Radial Velocity Pipeline: First Radial Velocities from EXPRES

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    The EXtreme PREcision Spectrograph (EXPRES) is an environmentally stabilized, fiber-fed, R=137,500R=137,500, optical spectrograph. It was recently commissioned at the 4.3-m Lowell Discovery Telescope (LDT) near Flagstaff, Arizona. The spectrograph was designed with a target radial-velocity (RV) precision of 30 cm s1\mathrm{~cm~s^{-1}}. In addition to instrumental innovations, the EXPRES pipeline, presented here, is the first for an on-sky, optical, fiber-fed spectrograph to employ many novel techniques---including an "extended flat" fiber used for wavelength-dependent quantum efficiency characterization of the CCD, a flat-relative optimal extraction algorithm, chromatic barycentric corrections, chromatic calibration offsets, and an ultra-precise laser frequency comb for wavelength calibration. We describe the reduction, calibration, and radial-velocity analysis pipeline used for EXPRES and present an example of our current sub-meter-per-second RV measurement precision, which reaches a formal, single-measurement error of 0.3 m s1\mathrm{~m~s^{-1}} for an observation with a per-pixel signal-to-noise ratio of 250. These velocities yield an orbital solution on the known exoplanet host 51 Peg that matches literature values with a residual RMS of 0.895 m s1\mathrm{~m~s^{-1}}

    First measurement of target and double spin asymmetries for polarized e- polarized p --> e p pi0 in the nucleon resonance region above the Delta(1232)

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    The exclusive channel polarized proton(polarized e,e prime p)pi0 was studied in the first and second nucleon resonance regions in the Q2 range from 0.187 to 0.770 GeV2 at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). Longitudinal target and beam-target asymmetries were extracted over a large range of center-of-mass angles of the pi0 and compared to the unitary isobar model MAID, the dynamic model by Sato and Lee, and the dynamic model DMT. A strong sensitivity to individual models was observed, in particular for the target asymmetry and in the higher invariant mass region. This data set, once included in the global fits of the above models, is expected to place strong constraints on the electrocoupling amplitudes A_{1/2} and S_{1/2} for the Roper resonance N(1400)P11, and the N(1535)S11 and N(1520)D13 states.Comment: 13 pages, 13 figure

    Potential of Core-Collapse Supernova Neutrino Detection at JUNO

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    JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

    Deep excursion beyond the proton dripline. I. Argon and chlorine isotope chains

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    The proton-unbound argon and chlorine isotopes have been studied by measuring trajectories of their decay-in-flight products by using a tracking technique with microstrip detectors. The proton (1p) and two-proton (2p) emission processes have been detected in the measured angular correlations "heavy-fragment"+p and "heavy-fragment"+p+p, respectively. The ground states of the previously unknown isotopes Cl30 and Cl28 have been observed for the first time, providing the 1p-separation energies Sp of -0.48(2) and -1.60(8), MeV, respectively. The relevant systematics of 1p- and 2p-separation energies have been studied theoretically in the core+p and core+p+p cluster models. The first-time observed excited states of Ar31 allow one to infer the 2p-separation energy S2p of 6(34) keV for its ground state. The first-time observed state in Ar29 with S2p=-5.50(18) MeV can be identified as either a ground state or an excited state according to different systematics

    Detection of the Diffuse Supernova Neutrino Background with JUNO

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    As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO
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