Torsional Alfvén and slow magnetoacoustic waves generated by a plasma in a magnetic field

An intense electron-antineutrino source with a hard spectrum (\(E_{{{\tilde v}_e}}^{\max }\) = 13 MeV and \(\left\langle {{E_{{{\tilde v}_e}}}} \right\rangle \) = 6.5MeV) can be created on the basis of the short-lived isotope ⁸Li (β^?-decay, T_1/2 = 0.84 s) formed via the (n, γ) activation of ⁷Li. In contrast to a reactor antineutrino spectrum whose uncertainty is large, particularly in the high-energy region \({E_{{{\tilde v}_e}}}\) > 6 MeV, which is experimentally relevant, the lithium \({\tilde v_e}\) spectrum is accurately determined. The proposed accelerator-driven experimental scheme with a neutron-producing target and a lithium converter as an intense \({\tilde v_e}\) source is an alternative to a nuclear reactor. The required amount of high-purity ⁷Li will be reduced in many times by using the suggested heavy-water LiOD solutions. A possible experiment involving the lithium source on search for sterile neutrinos in the mass region Δm² ≥ 0.2 eV² with a very high sensitivity to mixing-angle values down to sin²(2Θ) ≈ (7–10) × 10^–4 at the 95% C.L. has been considered.     

The concept of a powerful antineutrino source

A powerful antineutrino source with a hard [(n)\tilde] _e\tilde \nu _e spectrum obtained upon the (n, γ) activation of the ⁷Li isotope and the subsequent β⁻ decay (T _1/2 = 0.84 s) of the ⁸Li isotope with the emission of high-energy [(n)\tilde] _e\tilde \nu _e with E _v of up to 13 MeV was discussed. The source can be constructed both in the static regime (by covering the active reactor zone with highly purified ⁷Li) and in the dynamic regime of operation. In the dynamic regime, lithium is pumped over in a closed cycle through a converter (i.e., a volumetric reservoir) close to the active reactor zone and further to a remote detector. The source can be constructed on the basis of both highly purified ⁷Li isotope in the metal state and chemical compounds of the ⁷Li isotope. The setup can be developed on the basis of an intensive neutron source or an accelerator with a neutron-producing target. In the dynamic regime, the proposed lithium antineutrino source enables us to increase the cross-section of the ([(n)\tilde] _e\tilde \nu _e , d) reaction by two orders of magnitude over a purely reactor spectrum.     

Powerful dynamical neutrino source with a hard spectrum

A powerful dynamical neutrino source with a hard spectrum obtained via the (n, γ) activation of ⁷Li and a subsequent β^? decay (T _1/2=0.84 s) of ⁸Li with the emission of high-energy $\tilde \nu _e$ (up to 13 MeV) is discussed. In the dynamical system, lithium is pumped over in a closed cycle through a converter near the reactor core and further to a remote $\tilde \nu _e$ detector. It is shown that, owing to a large growth of the hardness of the total $\tilde \nu _e$ spectrum, the cross section for the interaction with a deuteron can strongly increase both in the neutral ( $\tilde \nu _e + d \uparrow n + p + \tilde \nu _e$ ) and in the charged ( $\tilde \nu _e + d \uparrow n + n + e^ +$ ) channel in relation to the analogous cross sections in the reactor $\tilde \nu _e$ spectrum.     

Hard antineutrino source based on a lithium blanket: A version for the accelerator target

The β^–-active ⁸Li isotope has a hard and well-defined antineutrino spectrum (E _ν ^max= 13.0 MeV, E _ν= 6.5 MeV) that ensures the reliable detection of the threshold reactions (ν _e, p) and (ν _e, d). An intense ν _e source is proposed within a scheme comprising an accelerator with a neutron-producing target and a lithium blanket. The density analysis of ⁸Li production in this blanket shows that the mass of highly pure ⁷Li can be reduced to 100–200 kg, as compared to ~19.5 t in the option with metallic ⁷Li, and the size of the source can be decreased by a factor of ~2.5, which is important for the proposed short-base experiments on the search for sterile neutrinos.     

Kinematic identification of the \betat branch in the decay of 11Li

The $ \beta$ -delayed ⁸ Li + t branch of the ¹¹Li decay was identified via kinematical analysis of the charged particles observed in coincidence. The back-to-back events observed in a narrow angular acceptance were compared to a Monte Carlo simulation. The ⁸ Li + t sum energy spectrum was fitted assuming that the decay occurs through an intermediate state in ¹¹Be . The resulting energy centroid and full-width half maximum for the intermediate state are 18.35(30)MeV and 1.5(4)MeV, respectively. The $ \beta$ -delayed ⁸ Li + t branching ratio obtained from the coincidence spectrum, BR _t = 0.93(8)×10^-4 , is in agreement with previous measurements but more precise.     

Measurements of the ratio Rdp of the quasi-elastic nd \rightarrow p(nn) to the elastic np \rightarrow pn charge-exchange process yields at zero proton emission angle over the 0.55-2.0 GeV neutron beam energy region

New experimental results on the ratio R_dp of the quasi-elastic charge-exchange yield at the outgoing proton angle $ \theta_{{p,{\rm Lab}}}^{}$ = 0^° for the nd $ \rightarrow$ p(nn) reaction to the elastic np $ \rightarrow$ pn charge-exchange yield are presented. The measurements were carried out at the Nuclotron of the Veksler and Baldin Laboratory of High Energies of the JINR (Dubna) at the neutron beam kinetic energies of 0.55, 0.8, 1.0, 1.2, 1.4, 1.8 and 2.0GeV. The intense neutron beam with small momentum spread was produced by break-up of deuterons which were accelerated and extracted to the experimental hall. In both reactions mentioned above the outgoing protons with the momenta p _p approximately equal to the neutron beam momentum p _{n, beam} were detected in the directions close to the direction of incident neutrons, i.e. in the vicinity of the scattering angle $ \theta_{{p,{\rm Lab}}}^{}$ = 0^° . Measured in the same data taking runs, the angular distributions of the charge-exchange reaction products were corrected for the well-known instrumental effects and averaged in the vicinity of the incident neutron beam direction. These corrected angular distributions for every of nd $ \rightarrow$ p(nn) and np $ \rightarrow$ pn charge-exchange processes were proportional to the differential cross-sections of the corresponding reactions. The data were accumulated by the Delta-Sigma set-up magnetic spectrometer with two sets of multiwire proportional chambers located upstream and downstream of the momentum analyzing magnet. Inelastic processes were considerably reduced by the additional detectors surrounding the hydrogen and deuterium targets. The time-of-flight system was applied to identify the detected particles. The new R_dp data are compared with the existing ones, which were obtained below 1GeV, and with the calculations which were made using the phenomenological NN amplitude sets.     

Neutron-rich hypernuclei in the chiral soliton model

The binding energies of neutron-rich strangeness S = ?1 hypernuclei are estimated in the chiral soliton approach using the bound state rigid oscillator version of the SU(3) quantization model. Additional binding of strange hypernuclei in comparison with nonstrange neutron-rich nuclei takes place at not large values of atomic (baryon) numbers, A = B ?? ??10. This effect becomes stronger with increasing isospin of nuclides, and for the ??nuclear variant?? of the model with rescaled Skyrme constant e. Binding energies of _?? ⁸ He and recently discovered _?? ⁶ H satisfactorily agree with data. Hypernuclei _?? ⁷ H, _?? ⁹ He are predicted to be bound stronger in comparison with their nonstrange analogues ⁷H, ⁹He; hypernuclei _?? ¹⁰ Li, _?? ¹¹ LI, _?? ¹² Be, _?? ¹³ Be, etc. are bound stronger in the nuclear variant of the model.     

Studying(\bar cs) spectroscopy in\bar vN collisions

Charmed strange meson neutrinoproduction is investigated. TheD _s ^? (1970) antineutrino production rate is measured. Two higher \((\bar cs)\) states are seen in the decay channels γD _s ^* (2110) andD ^*K, respectively.     

Status of the NPDGamma Experiment at the SNS

The main goal of the NPDGamma experiment is to measure the gamma-ray asymmetry with respect to the neutron spin direction in the nuclear reaction $\overrightarrow{n}+ p \rightarrow d + \gamma$ . The up-down asymmetry A _γ has a predicted size of the order of 5 ·10^???8 , and the NPDGamma experiment is designed to measure it with an uncertainty of about 10^???8. To test the entire apparatus the gamma-ray asymmetry from neutron capture was measured using a Cl target followed by measurements on Al to establish the relevant background levels. At present the experiment is taking data with a liquid H ₂ target to measure the parity violation on the $\overrightarrow{n} + p \rightarrow d + \gamma$  reaction and extract the ΔI?=?1 part of the hadronic weak interaction.     

First measurement of the polarisation transfer on the proton in the reactionsH(\vec e,e'\vec p) andD(\vec e,e'\vec p)

The measurement of the polarisation transfer to the proton in the reactions $H(\vec e,e'\vec p)$ and $D(\vec e,e'\vec p)$ performed with longitudinally polarised electrons in quasi-free kinematics is presented. The coincidence measurement was executed atQ ²≈8fm ^?2 using the 855 MeV, c.w. beam of the Mainz Microtron MAMI. The recoil polarisation was determined by means of a carbon analyser. The experiment shows that the binding of the nucleon does not modify the polarisationP _x of the recoil proton within an error ofΔ P _x/P_x≈10%. The measured polarisation agrees with recent theoretical predictions. Implications for the measurement of the electric form factor of the neutron using the $D(\vec e,e'\vec n)$ reaction are discussed.     

Magnetic moment of the 19/2+ isomer in135Ce

Employing the time-integral PAC technique with an external magnetic field, the g-factor of the 19/2⁺ state at 2,125.6 keV in¹³⁵Ce was determined to be g=?0.07(1). This value favours a predominant (h ₁₁ ^2/?2 s ₁ ^2/?1 ) neutron configuration for this level. Its meanlife has been redetermined with improved precision to be τ=11.8(5) ns.     

Photon Asymmetries in {nd\rightarrow} 3 Hγ Using EFT({/\!\!\!\pi}) Approach

The parity-violating Lagrangian of the weak nucleon-nucleon (NN) interaction in the pionless effective field theory (EFT( \({/\!\!\!\pi}\) )) approach contains five independent unknown low-energy coupling constants (LECs). The photon asymmetry with respect to neutron polarization in \({np\rightarrow d\gamma A_\gamma^{np}}\) , the circular polarization of outgoing photon in \({np\rightarrow d\gamma P_\gamma^{np}}\) , the neutron spin rotation in hydrogen \({\frac{1}{\rho}\frac{d\phi^{np}}{dl}}\) , the neutron spin rotation in deuterium \({\frac{1}{\rho}\frac{d\phi^{nd}}{dl}}\) and the circular polarization of γ-emission in \({nd\rightarrow}\) ³ Hγ \({P^{nd}_\gamma}\) are the parity-violating observables which have been recently calculated in terms of parity-violating LECs in the EFT( \({/\!\!\!\pi}\) ) framework. We obtain the LECs by matching the parity-violating observables to the Desplanques, Donoghue, and Holstein (DDH) best value estimates. Then, we evaluate photon asymmetry with respect to the neutron polarization \({a^{nd}_\gamma}\) and the photon asymmetry in relation to deuteron polarization \({A^{nd}_\gamma}\) in \({nd\rightarrow}\) ³ Hγ process. We finally compare our EFT( \({/\!\!\!\pi}\) ) photon asymmetries results with the experimental values and the previous calculations based on the DDH model.     

Search for the K L 0 → π0ν \tilde v decay at the INEP U-70 accelerator: The KLOD project

The rare decay K _L ⁰ → π⁰ν $ \tilde v $ branching ratio measurement is one of the clearest Standard Model test. Calculations based on the SM predict Br(K _L ⁰ → π⁰ν $ \tilde v $ ) ≈ 2.8 × 10^?11, but the most accurate experimental value Br(K _L ⁰ → π⁰ν $ \tilde v $ ) < 6.7 × 10^?8 (90% C.L.). We present design of a new experimental setup KLOD (U-70 accelerator, IHEP, Protvino) for K _L ⁰ → π⁰ν $ \tilde v $ branching ratio measurement. Sensitivity of the KLOD experiment will be enough for registration of 2.4 events K _L ⁰ → π⁰ν $ \tilde v $ for every 10 days of the data taking (according to SM predictions).     

Analysis of average primary gamma-transition intensities and cross sections of the113Cd(n, γ) reaction

A combined analysis of the available data on the primaryγ-ray intensities from the¹¹³Cd(n, γ) reaction atE _n=1.9 and 24.3 keV neutron energies together with the data on¹¹³Cd neutron capture cross sections in theE _n=3–200 keV energy region was carried out. The neutron strength functions were determined asS _n0=(0.260±0.073) 10^?4 and S_n1=(5.06±0.67) 10^?4. No spin-orbit splitting of thep-wave neutron strength function was found. The energy dependence of theE 1 radiative strength function {ie147-01} was fitted by the Kadmenski-Furman model somewhat better than by a standard Lorentzian. TheM 1 giant resonance parameters were obtained as E _G ^{M 1} =8.8±1.6 MeV and Γ _G ^{M 1} = 4.7±2.6 MeV. The neutron capture cross section of¹¹³Cd from its isomeric state ({ie147-02}=11/2^?, E ₁ ^m =263.7 keV) was calculated.     

Search for Θ+(1540) in exclusive proton-induced reaction p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N) at the energy of 70 GeV

A search for narrow Θ⁺(1540), a candidate for a pentaquark baryon with positive strangeness, has been performed in an exclusive proton-induced reaction $p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N)$ on carbon nuclei or quasifree nucleons at $E_{beam} = 70GeV(\sqrt s = 11.5GeV)$ studying nK ⁺, pK _S ⁰ , and pK _L ⁰ decay channels of Θ⁺(1540) in four different final states of the $\Theta ^ + \bar K^0 $ system. In order to assess the quality of the identification of the final states with neutron or K _L ⁰ , we reconstructed Λ(1520) → nK _S ⁰ and ? → K _L ⁰ K _S ⁰ decays in the calibration reactions p + C(N) → Λ (1520)K ⁺+C(N) and p+C(N) → p?+C(N). We found no evidence for a narrow pentaquark peak in any of the studied final states and decay channels. Assuming that the production characteristics of the $\Theta ^ + \bar K^0 $ system are not drastically different from those of the Λ(1520)K ⁺ and p? systems, we established upper limits on the cross-section ratios $\sigma (\Theta ^ + \bar K^0 )/\sigma (\Lambda (1520)K^ + ) < 0.02$ and $\sigma (\Theta ^ + \bar K^0 )/\sigma (p\phi ) < 0.15$ at 90% C.L. and a preliminary upper limit for the forward-hemisphere cross section $\sigma (\Theta ^ + \bar K^0 )$ nb/nucleon.     

Level structures in the 114 In nucleus

High-spin states in ¹¹⁴In were populated using the reaction ¹¹⁰Pd(⁷Li, 3n)¹¹⁴In at a beam energy of 26MeV. The level scheme of ¹¹⁴In consisting of six bands is established up to excitation energy ～ 5MeV and spin ～ 17 ? with the addition of 58 new transitions and their configurations are discussed. The intense positive-parity dipole cascade may be interpreted as shears band based on $ \pi$ [(g _9/2)^-1] ? $ \nu$ [(g _7/2/d _5/2)(h _11/2)²] configuration. The $ \Delta$ I = 2 bands based on proton excitation have been observed in ¹¹⁴In for the first time.     

Isotope shift measurements in the atomic spectrum of lanthanum (LaI)

Using the reactor-produced lanthanum isotope ₅₇ ¹³⁷ La, the highly enriched rare ₅₇ ¹³⁸ La and the stable ₅₇ ¹³⁹ La, the isotope shift has been measured in five lines of the La I-spectrum with the aid of a pressure-scanned Fabry-Pérot interferometer. The isotope shift data obtained show surprisingly large specific mass effects, arising from configuration mixing of levels with a 4f electron involved. The changes in mean square charge radiusδ〈r ²〉 of these nuclei extracted from the experimental isotope shift constants C_exp are compared with the corresponding values for the isotonic barium nuclei, where similar anomalies in the isotope shifts occur.     

Determination of theL-shell conversion coefficient for the 26 keV Mössbauer transition in161Dy

TheL-shell conversion coefficient of the 26 keV Mössbauer transition in¹⁶¹Dy has been determined to be α_L=2.4 _?0.2 ^+0.3 by coincidence techniques using high resolution Ge(Li) and Si(Li) detectors. With theoretical values for theM- andN-shells the total conversion coefficient is calculated to be α_tot=2.9 _?0.2 ^+0.3 .     

Evidence for a 3.6 minute isomeric 12− state of the πh 11 2/−1 vi 13 2/−1 configuration in206Tl and effective two-particle interactions

Using the²⁰⁴Hg(α, pn)-reaction andα-particles of energies 39–55 MeV, we have found an isomeric 3.6 min 12^? state in²⁰⁶Tl at 2,642.9 keV which has the two-hole configurationπh ₁₁ ^2/?1 vi ₁₃ ^2/?1 The 12^? state decays mainly by anE5 transition of energy 1,021.4 keV to a 7⁺ state at 1,621.5 keV whose main configuration isπs ₁ ^2/?1 vi ₁₃ ^2/?1 There is, in addition, evidence for a weak 565 keVM 4 branch to an 8⁺ state at 2,078 keV whose main configuration should beπh ₁₁ ^2/?1 vf ₅ ^2/?1 . The 7⁺ state decays by a stretched cascade ofγ-rays to states of the following values ofJ ^π and excitation energy: 5 _? ⁺ , 1,405.4 keV; 4^?, 952.1 keV; 2^?, 265.8 keV and 0^?, 0 keV. The main configurations of these states areπh ₁₁ ^2/?1 vp ₁ ^2/?1 ,πd ₃ ^2/?1 vf ₅ ^2/?1 ,πd ₃ ^2/?1 vp ₁ ^2/?1 andπs ₁ ^2/?1 vp ₁ ^2/?1 respectively. From the nuclear masses of²⁰⁸Pb,²⁰⁷Pb,²⁰⁷Tl, and²⁰⁶Tl and the experimental excitation energies it is possible to obtain the proton hole-neutron hole interaction in²⁰⁶Tl. This interaction is compared with the calculations of Kuo and Herling and the discrepancies are discussed. The 12^?→8⁺ M4 transition rate is reduced because of destructive interference between the protonh _11/2→d _3/2 and the neutroni _13/2→f _5/2 contributions. The magnitude of the reduction is accurately reproduced by the wave functions of Kuo and Herling. The 12^?→7⁺ E5 transition rate is about twice as large as the single-holeπh ₁₁ ^2/?1 πs ₁ ^2/?1 transition rate. This deviation is fully explained by the configuration admixtures in the 7⁺ state, given by Kuo and Herling.     

Decays of(vh_{11/2} ^n )^{10 + } and(\pi d_{5/2} vh_{11/2} ^n )^{25/2 + } isomers in even-A Sn and odd-A Sb nuclei

Isomeric decays in^{116, 118, 120}Sn and^{119, 120}Sb have been studied by measurements of delayedγ-rays following reactions of 26–40 MeV⁷Li ions on Cd targets. A 6.3 μs isomer of \((vh_{11/2} ^n )^{10 + } \) character in¹²⁰Sn is reported. The experimental variation inB(E2, 10⁺ → 8⁺) between \(vh_{11/2} ^n \) states in^{116, 118, 120, 128, 130}Sn is compared with the expected dependence on vh^11/2 subshell occupation number. Isomerism in Sb nuclei is also discussed, and a known high-spin isomer in¹¹⁹Sb is assigned the same seniority-three configuration \((\pi d_{5/2} vh_{11/2} ^n )^{25/2 + } \) as a well-established 340 μs isomer in¹¹⁷Sb.