Cold reaction valleys in the radioactive decay of superheavy 286112, 292114, and 296116 nuclei

Cold reaction valleys in the radioactive decay of superheavy nuclei ²⁸⁶112, ²⁹²114, and ²⁹⁶116 are studied taking Coulomb and Proximity Potential as the interacting barrier. It is found that in addition to alpha particle, ⁸Be, ¹⁴C, ²⁸Mg, ³⁴Si, ⁵⁰Ca, etc. are optimal cases of cluster radioactivity since they lie in the cold valleys. Two other regions of deep minima centered on ²⁰⁸Pb and ¹³²Sn are also found. Within our Coulomb and Proximity Potential Model half-life times and other characteristics such as barrier penetrability, decay constant for clusters ranging from alpha particle to ⁶⁸Ni are calculated. The computed alpha half-lives match with the values calculated using Viola-Seaborg-Sobiczewski systematics. The clusters ⁸Be and ¹⁴C are found to be most probable for emission with T _1/2 < 10³⁰ s. The alpha-decay chains of the three superheavy nuclei are also studied. The computed alpha-decay half-lives are compared with the values predicted by Generalized Liquid Drop Model and they are found to match reasonably well.     

Coulomb forces in the three-body problem with application to direct nuclear reactions

Faddeev equations are considered in the case of three charged particles interacting with both separable nuclear two-body interactions and also including Coulomb forces. Modified Faddeev equations with Coulomb Green's functions are introduced. The three-body amplitudes are given into pure Coulomb and distorted-Coulomb amplitudes. Introducing a decomposition in the angular momentum states, a set of three-body integral equations is obtained. The effect of pure coulomb amplitudes is studied in direct nuclear reactions and found to give a large contribution to the cross sections. The three-body integral equations obtained are applied for direct nuclear reactions. The angular distributions for¹²C(⁶Li,d)¹⁶O,¹⁶O(⁶Li,d)²⁰Ne, and¹²C(⁶Li,α)¹⁴N transfer reactions are calculated as well as for the⁶Li elastic scattering on¹²C. From the good agreement between the theoretically calculated and experimental data, better spectroscopic factors are extracted. The effect of including Coulomb forces in the three-body problem is found to improve the results by about 16.26%.     

Extensive spectroscopic calculations on 12 low-lying electronic states of AlN molecule including transition properties

Using the CASSCF method followed by the internally contracted MRCI approach in combination with the correlation-consistent basis sets, the potential energy curves (PECs) are calculated for the X³Π, A³Σ^-, B³Σ⁺, C³Π, E³Δ, a¹Σ⁺, b¹Π, c¹Δ, d¹Σ⁺, e¹Π, 2³Σ^? and 3³Σ^? electronic states of AlN molecule for internuclear separations from 0.1 to 1.0 nm. All the electronic states correlate to the three dissociation channels, Al(²P_u) + N(⁴S_u), Al(²P_u) + N(²D_u) and Al(²P_u) + N(²P_u). Of these 12 electronic states, only the 2³Σ^? possesses the double well. The PECs determined by the internally contracted MRCI approach are corrected for size-extensivity errors by means of the Davidson correction. The convergent behavior of present calculations is observed with respect to the basis set and level of theory. The effect of core-valence correlation and scalar relativistic corrections on the spectroscopic parameters is discussed. Scalar relativistic correction calculations are performed by the third-order Douglas-Kroll Hamiltonian approximation at the level of cc-pVTZ basis set. Core-valence correlation corrections are included with a cc-pCVTZ basis set. All the PECs are extrapolated to the complete basis set limit. The spectroscopic parameters are evaluated by fitting the first ten vibrational levels when available, which are obtained by solving the ro-vibrational Schrödinger equation with the Numerov’s method. The spectroscopic parameters are compared with those reported in the literature. Excellent agreement is found between the present results and the measurements. Analyses show that the spectroscopic parameters reported in this paper can be expected to be reliably predicted ones. The Franck-Condon factors and radiative lifetimes of the transitions from the A³Σ^?, B³Σ⁺, C³Π, a¹Σ⁺ and b¹Π electronic states to the ground state are calculated for several low vibrational levels, and some necessary discussion has been made.     

The competition between different degrees of freedom in the structure of the quintet states of negative parity of some even-even Sn isotopes

Levels 2⁺, 3⁻, 1⁻, 2⁻, 3⁻¹, 5⁻ are interpreted as eigenvalues of a boson expanded Hamiltonian containing a shell model term, pairing, and quadrupole-quadrupole and octupole-octupole interaction. The expansion is performed in terms of standard RPA noncollective phonons and the so-called correlated phonons which are related to the RPA collective phonons by a canonical transformation whose parameters are determined so that the energy of the ground state is minimum. The noncollective degrees of freedom are included via an effective Hamiltonian depending on energy. Formalism is applied to ¹¹⁴Sn, ¹¹⁶Sn, and ¹¹⁸Sn. Also, transition probabilities and quadrupole moments are calculated. Results are compared with experimental data as well as with the previous theoretical calculations.     

Isovector correlations and pion single charge exchange reactions in light nuclei

The reactions ⁷Li(π⁺, π⁰)⁷Be(g.s.), ⁷Li(π⁺, π⁰)⁷Be1(429keV) and ¹³C(π⁺, π⁰)¹³N(g.s.) are treated in DWIA, including corrections arising from two-step processes in which an intermediate state is reached in the course of the charge exchange. The distortions are introduced by means of a first-order optical potential; no special assumptions of extreme high energy limits are made. The closure sum over intermediate states in the two-step charge exchange mechanism leads to an isovector two-particle correlation function whose properties for p-shell nuclei are discussed in detail. Consequences of the introduction of effective transition operators for the single-step mechanism, with and without spin-flip, and for the two-step contribution are discussed, as are the allowable modifications in nuclear shell radii consistent with present knowledge of Coulomb energies. Comparison is made with experiment — in the case of the separated ⁷Be states, for the first time — and with other theoretical approaches.     

Ag离子注入非晶SiO2的光学吸收、拉曼谱和透射电镜研究

能量为200keV的Ag离子，以1×10¹⁶，5×10¹⁶，1×10¹⁷ cm^-2的剂量分别注入到非晶SiO₂玻璃，光学吸收谱显示：注入剂量为1×10¹⁶ cm^-2的样品的光吸收谱为洛伦兹曲线，与Mie理论模拟的曲线形状一致；注入剂量较大的5×10¹⁶，1×10¹⁷ cm^-2的谱线共振吸收增强，峰位红移并出现伴峰. 透射电镜观察分析表明，注入剂量不同的样品中形成的纳米颗粒的大小、形状、分布都不同，注入剂量较大的还会产生明显的表面溅射效应，这些因素都会影响共振吸收的峰形、峰位和峰强. 当注入剂量达到1×10¹⁷ cm^-2时，Ag纳米颗粒内部可能还形成了杂质团簇. 关键词： 离子注入 纳米颗粒 共振吸收 红移     

类铍离子低激发态等电子系列的能量、精细结构和超精细结构

采用多组态相互作用方法及Rayleigh-Ritz 变分方法，并考虑相对论修正和质量极化效应，获得了类铍离子等电子系列（Z=4-10）低激发态1s²2p2p ¹D^e和1s²2p3p ³P^e的相对论能量。同时还计算了精细结构和超精细结构。计算结果与其他理论和实验符合的很好。     

Competition betweenβ +- andβ −-decays from the transitional nucleus74As

A theoretical study of theβ ⁺- andβ ^?-decays of the⁷⁴As nucleus is performed. Both non-relativistic and relativistic formfactor coefficients are calculated in the framework of the asymmetric rotor model with admixtures of two quasiparticles for transitional nuclei. The induced interactions are shown to have small contributions to the values of the formfactor coefficients in this case. The theoretical results for the principal observables are in good agreement with the experimental data in the case of the beta decays to the 2⁺ final states. The failure in describing the beta observables corresponding to the transitions to the ground states points to the existence of a more complex structure of the 0⁺-states in the daughter nuclei⁷⁴Se and⁷⁴Ge.     

Excited states of HCl

Ab initio CI calculations are presented for potential curves for the valence states of HCl, for the vertical electronic spectrum and for the potential curve for the B ¹Σ⁺ state. The valence ¹Π, ³Π and ³Σ⁺ states are found to be repulsive. Calculated vertical excitation energies are in good agreement with experiment. The B ¹Σ⁺ curve is predicted to have a double minimum.     

Coupled-channels study of projectile and target excitation in the scattering of 6Li from 12C and 16O

Coupled-channels calculations are presented tor elastic and inelastic ⁶Li + ¹²C scattering at E_c.m. = 16 MeV and 20 MeV, and for ⁶Li + ¹⁶O at 18.7 MeV. Excitation of states within ⁶Li, ¹²C and ¹⁶O are treated with rotational, rotation-vibration and vibrational models only. The 3⁺⁶Li and 2⁺¹²C states are strongly coupled to the elastic scattering and reduce the strengths of both the real and imaginary potentials. The 3^?16O state reduces only the strength of the imaginary potential. All other states are weakly coupled and have little effect on each other or the potential. The data are reasonably well described, with there being some preference for the 3^? state in ¹²C to be K = 0. Excitation of the 0₂⁺ state in ¹²C requires a combination of β-vibration and monopole breathing-mode form factors. The deformation lengths found are in poor agreement with those deduced from electron or proton scattering.     

16, 18O induced transfer reactions on122, 120Sn

The reactions¹²⁰Sn+72 MeV¹⁸O and¹²²Sn+74 MeV¹⁶O were investigated with time of-flightΔE-E-telescopes. Data are presented for all quasi-elastic reaction channels. The two neutron stripping and pickup reactions (¹⁸O,¹⁶O), (¹⁸O,²⁰O) and (¹⁶O,¹⁸O) are analyzed in detail. It is shown that these heavy ion induced two neutron transfer reactions proceed with essentially the same type of selectivity as the corresponding light ion induced reactions. The differential cross sections for transfer reactions leaving the^{120, 122}Sn nuclei in their 2⁺ first excited states are shown to be influenced by interference effects due to additional inelastic excitations.     

High resolution C nuclear magnetic resonance spectra for symmetrical orthodihalobenzenes including long-range CH couplings

Analysis of high resolution ¹³C NMR spectra for symmetrical orthodihalobenzenes have provided all long-range ¹³CH coupling values in orthodichloro-, dibromo-, and diiodobenzene. Furthermore, since the analyses were sensitive to the sign of the coupling constants, the relative signs of these long-range ¹³CH couplings have been determined from unique spectral fits. The substituent effects on the chemical shifts in this series of compounds appear to be additive. The ¹³CH couplings are compared with coupling values in other compounds and are shown to be related to substituent electronegativity. The absolute magnitude of the ¹³CH couplings for these halogen-substituted compounds are larger than those observed in benzene, with but one exception. In all cases, three-bonded ¹³CH couplings are found to be larger than the two-bond values.     

Rydberg states of the HeH+ ion calculated by ab initio methods: potential energies and effective principal quantum numbers

More than 80 excited electronic states of the hydrohelium ion HeH⁺ of ^{1, 3}Σ⁺, ^{1, 3}Π, ^{1, 3}Δ, ^{1, 3}Φ and ^{1, 3}Γ symmetry have been calculated ab initio up to n = 6 for internuclear distances ranging from 0.5 to 100 bohr. The computations involve a configuration interaction (CI) treatment based on a home-made suite of programs that uses special basis sets designed for the representation of molecular Rydberg states. The results are compared with previous computations where these are available (up to n = 4), and it is found that except for the very lowest excited states, the present energies are consistently lower than those obtained previously, with an average lowering corresponding to several hundred cm^?1. It is shown that with the exception of its ground state, HeH⁺ is an effective one-electron system having an overall electronic structure similar to H⁺₂. The interaction of the excited electron with the He⁺ 1s core electron causes small singlet–triplet splittings to appear and ?-mixing interactions to occur, that are not present in H⁺₂.     

Elastic and inelastic scattering of 79.5 MeV 11B and 87.5 MeV 10B ions

The elastic scattering of 79.5 MeV ¹¹B ions has been studied for seven targets ranging in mass from ²⁴Mg to ¹⁹⁷Au and of 87.5 MeV ¹⁰B ions for three of these targets (^{24, 25}Mg, ⁶⁰Ni). Angular distributions were measured from ~10° c.m. in steps of 0.5°, to angles beyond 40° c.m. where the elastic cross sections are ? 10^?3 of the Rutherford values (except for ¹⁹⁷Au). Inelastic data for exciting the lowest 2⁺ states of ^24,26Mg and ⁶⁰Ni were also obtained. Important odd-A-even-A differences are observed in the ¹¹B elastic angular distributions for the Mg and Al targets; for ¹⁰B scattering these are obscured by projectile quadrupole moment effects on the elastic scattering. The elastic data were analyzed using the optical model with potentials of both Woods-Saxon and double-folding form. The data for both ¹⁰B and ¹¹B are consistent with the potential obtained in the folding model with the M3Y interaction without renormalization. The inelastic data were analyzed by the distorted-waves method.     

Transport of excess charge carriers in liquid and solid hydrogen

The temperature dependence of the drift mobility of excess charge carriers in liquid and solid hydrogen has been investigated. Both negative and positive carriers are observed in the liquid with mobilities ～ 5 × 10^-3 cm² V^-1 sec^-1 at 15 K; the mobile carriers in the solid are believed to be negatively Charged with a mobility ～ 6 × 10^-6 cm² V^-1 sec^-1 at 13 K. The mechanisms of charge localization and transport are discussed.     

Nanodosimetry of 125I – Auger electrons – Experiment and modeling

The experiment with ¹²⁵I-Auger electrons, interacting with gaseous nitrogen with size equivalent to segment of DNA in mass per unit area scale, are described. The discrete ionization cluster-size distributions have been obtained. The shapes of which are definitely determined by the size of the interaction volumes. The volume sizes studied in the present work are comparable with a segment of DNA and of nucleosome. The experiments have been carried out with the set up, called Jet Counter, and are the first cluster-size distributions as yet measured for an Auger-electron emitter like ¹²⁵I. The experimental results have been compared with those obtained by Monte Carlo simulation. The results for ¹²⁵I have been compared with calculated cluster size distribution for ¹³¹I.     

Radiative pion capture in 12C and 16O

Radiative pion capture in ¹²C and ¹⁶O is investigated. An effective interaction Hamiltonian based upon the CGLN theory is employed. Capture rates in ¹²C and ¹⁶O from Is and 2p pionic orbits are calculated by using the nuclear model of Kamimura, Ikeda and Arima for the odd parity states of ¹²C, and that of Walker with strong ground state correlations, for the odd parity states of ¹⁶O. The results are compared with those of the 1p-1h nuclear model under the Tamm-Dancoff and random phase approximations of Gillet and Vinh Mau. Detailed examinations are made for the transitions to low-lying states with 1⁺ and 2⁺ for ¹²C and with 1^?, 2^? and 3^? for ¹⁶O by using the Cohen-Kurath and the Walker models, respectively. The results are in good agreement with the recent experimental data from Berkeley.     

Level structure of 99Tc by inelastic scattering and proton stripping

The ⁹⁸Mo(³He, d)⁹⁹Tc and ⁹⁹Tc(d, d') reactions have been used to study the levels of of ⁹⁹Tc. Spin-parity assignments are made for nearly all states below 1.5 MeV excitation. Strong j-dependence is noted for l = 1 transitions in the proton stripping reaction, making possible several new spin assignments. The inelastic scattering data on ⁹⁹Tc are compared to similar data on ⁹⁸Mo, and are found to be in agreement with a coupling scheme based on a shell model with good seniority.     

Non-orthogonality effects in heavy-ion transfer reactions

Calculations are made of the effects arising from the non-orthogonality of channel states in heavy-ion neutron transfer reactions, as well as the associated elastic-scattering processes. A single iteration is performed upon the integral equations associated with the coupled-channel treatment of the transfer process. The reactions considered are ¹³C(¹⁶O, ¹⁷O)¹²C leading to the ground state and first excited state of ¹⁷O and the ²⁹Si(¹⁶O, ¹⁷O)²⁸Si reaction leading to the first excited state of ¹⁷O. Corrections are found to be as large as 10 % at angles where the cross sections are sizeable. Similar results are obtained for the elastic-scattering processes. The choice of reactions was made so as to emphasise the importance of these corrections.Consideration of the errors associated with the depiction of bound states in terms of a sum of Hankel functions and the use of a local-momentum approximation for the channel motion suggests that the figure for the correction represents an upper bound.     

Resonance states in 12C and α-particle condensation

The states with J^π = 0⁺, 2⁺, and 4⁺ of ¹²C with excitation energies less than about 15 MeV are investigated with the alpha condensate wave function with spatial deformation and by using the method of ACCC (analytic continuation in the coupling constant) which is necessary for a proper treatment of resonance states. The calculated energy and width of the recently observed 2₂⁺ state are found to be well reproduced. The obtained 2₂⁺ wave function has a large overlap with a single condensate wave function of 3α gas-like structure. The density distribution is shown to be almost the same as that of the 0₂⁺ state that is regarded as a 3α Bose-condensed state, if the energy of the 2₂⁺ state is scaled down to the same value as the one of the 0₂⁺ state. Furthermore, the kinetic energy, nuclear interaction energy, and Coulomb interaction energy of the calculated 2₂⁺ state are shown to be very similar to those of the 0₂⁺ state. We conclude that the 2₂⁺ state has a structure similar to the 0₂⁺ state of Bose-condensate character with a dilute 3α gas-like structure. In addition, the resonance states, 0₃⁺, 0₄⁺, 4₂⁺, are also discussed.