Magnetic hyperfine interaction in muonic indium,osmium and mercury

The magnetic hyperfine interaction in several muonic atoms has been measured. The magnetic splittings of the 1s _1/2, 2s _1/2 and 2p _1/2 muon states in the 9/2⁺ ground state of¹¹⁵In, determined by measuring muonic X rays areΔE _mag(1s _1/2,¹¹⁵In 9/2⁺)=3580±70 eVΔE _mag(2s _1/2,¹¹⁵In 9/2⁺)=525±120 eVΔE _mag(2p _1/2,¹¹⁵In 9/2⁺)=850±180 eV. The magnetic splitting of nuclearγ rays in the presence of a muon in the 1s _1/2 state yields for the 1/2^? ground state in¹⁹⁹HgΔE _mag(1s _1/2,¹⁹⁹Hg 1/2^?)=468±115 eV and the following values for the first excited 2⁺ states in the nuclei^190,192Os and²⁰⁰Hg:ΔE _mag(1s _1/2,¹⁹⁰Os 2⁺)=665± ₄₀ ⁸⁰ eVΔE _mag(1s _1/2,¹⁹²Os 2⁺)=800±80 eVΔE _mag(1s _1/2,²⁰⁰Hg 2⁺)=655± ₇₅ ¹⁰⁵ eV. These data are compared with calculations using different nuclear models.     

Strange charmed baryons in QCD

QCD sum rules are used to predict the mass differences between strange and nonstrange single charmed baryons inSU (3) sextets 1/2⁺, 1/2^?, 3/2⁺ and antitriplet 1/2⁺ as well as the mass of the lowest nonstrange stateΣ _c ^++′ in the 3/2⁺ sextet. The mass difference obtained for the antitriplet 1/2⁺ is in a good agreement with the available experimental data.     

Gyromagnetic ratios of excited states in 150Sm and 152Sm

The gyromagnetic ratios of the 2₁⁺, 4₁⁺, 6₁⁺, 2₂⁺, and 2₃⁺ states in ¹⁵⁰Sm and the 2₁⁺, 4₁⁺, 6₁⁺, 8₁⁺, 10₁⁺, 2₂⁺, and 2₃⁺ levels in ¹⁵²Sm have been measured using the transient field perturbed γ-ray angular correlation technique. States of interest were populated by multiple Coulomb excitation using 150- and 220-MeV ⁵⁸Ni beams. The present results display no significant deviation from constancy of the g-factors of all levels investigated in either isotope separately or of corresponding states in ^150,152Sm. These findings are compared with available prior measurements and assessed in terms of applicable theoretical model calculations.     

Thermoelectric power of the vitreous electrolyte (AgI)0.79(Ag2O.B2O3)0.21

We have determined the thermoelectric power ? of the high ionic conductivity glass (AgI)_0.79(Ag₂O.B₂O₃)_0.21; ? is negative throughout the investigated T range, 320–500 K. The heat of transport of the mobile Ag⁺, Q_Ag, taken as the slope of the straight line fitting ? versus 1/T, is quite lower than the activation energy obtained from conductivity data, viz. Q_Ag = 2.81 kcal/mole^-1 < E_act = 4.34 kcalmole^-1. To circumvent this discrepancy, the analysis of the experimental data is carried out as follows: (i) it is supposed that Q_Ag = E_act in agreement with the free ion theory for solid electrolytes; (ii) the vibrational part of the silver ion entropy, S(Ag⁺, vib), is assumed to be equal to the entropy of silver, S(Ag); (iii) on the ground of a structural model for this kind of glasses, the ideal configurational entropy of the mobile Ag⁺, S(Ag⁺, conf)_id, is evaluated through a statistical approach. The ideal ionic entropy is defined as S(Ag⁺)_id = {S(Ag⁺, vib) + S(Ag⁺, conf)_id}; (iv) the difference {S(Ag⁺)_exp - S(Ag⁺)_id} is viewed as an excess entropy and is described according to the classical model of the regular solutions.     

Investigating the Double Beta Decay of <Superscript>58</Superscript>Ni

Double beta decay (β + EC, EC/EC) of ⁵⁸Ni is investigated at France’s Modane Underground Laboratory (4800 m water equivalent) using the OBELIX ultralow-background HPGe detector with a sensitive volume of 600 cm³ and a natural nickel sample of ~68% 58Ni with a mass of ~21.7 kg. After preliminary analysis of the experimental data accumulated over ~144 days, new experimental limits are obtained for the 2νβ⁺EC decay of ⁵⁸Ni to the 0⁺ ground state and the 2 ₁ ⁺ , 811 keV excited state of ⁵⁸Fe, and for the 2νEC/EC decay of ⁵⁸Ni to the 2 ₁ ⁺ , 811 keV and 2 ₂ ⁺ , 1675 keV excited states of ⁵⁸Fe. The limits are T_1/2(β⁺EC,0→0⁺) > 1.7 × 10²² yr, T_1/2(β⁺EC,0→2 ₁ ⁺ ) > 2.3 × 10²² yr, T_1/2(EC/EC,0→2 ₁ ⁺ ) > 3.3 × 10²² yr, and T_1/2(EC/EC,0→2 ₂ ⁺ ) > 3.4 × 10²² yr. Experimental limit T_1/2(0νEC/EC–res, 1918 keV > 4.1 × 10²² yr is obtained for resonant neutrinoless radiative EC/EC decay with an energy of 1918.3 keV. All limits are at 90% CL.     

Comments on the measurements of vibrational intensity in the photoelectron spectra of N2 and CO,for the ionic ground state

Over 50 experimental values of the photoelectron intensity I(v′ = 1) (normalized to I(v′ = 0) equal to 100) for the N₂⁺, X²Σ_g⁺ photoelectron band, as well as 17 values of I(v′ = 1) for CO⁺, X²Σ⁺, are gathered or calculated from literature data, compared and discussed. Differences in the types of analyzer used, the instrumental conditions, the character of the UV light employed and the type of possible intensity corrections make such a comparison difficult, leave unexplained discrepancies and show the necessity of more systematic experimental investigations.     

Comparative study of the semiempirical three-parameter potential energy functions for diatomic molecules

A comparative study is made of four three-parameter semiempirical potential energy functions for 32 electronic states of diatomic molecules and their ions:n ₂:X¹gS _g ⁺ ,B ³π_g,A ³ gS_u,C ³ _u,B′ ³ gS_u.a ¹ π_g, a′gS _u ^? ,Ω ¹δ_u N ₂ ⁺ :X ² gS _g ^gS +A ² π,C ² gS _u ⁺ ,B ² gS _u ⁺ CO:X¹gS⁺,a ³ π, a′³ gS_u,e ³ gS^?,d ³gD₁,A ¹π CO⁺:X²gS⁺,A ² π,B ²gS⁺ O₂:X³gS _g ^? ,B ³ gS_u,c ¹ gS _u ^? ,b ¹gS _g ^s ,a ¹ δ_g,c ³ δ_u O ₂ ⁺ :X ²π_g,A ² π_g, a¹ π_g,b ⁴ gS _g ^? A program for numerically integrating the radial Schrödinger equation by the Cooley method is worked out. Certain additional units are introduced to conserve computer time. The resulting vibrational levels are compared with the experimental levels for all the electronic states studied. It is concluded on the basis of this analysis that it is not possible to describe equally well all the electronic states of various molecules on the basis of any single three-parameter potential function. A method for choosing a potential function for describing some particular electronic state of a diatomic molecule is proposed.     

Nuclear shapes of the transitional nuclei 186, 188, 190, 192Os

Excitation functions at θ_lab = 130° have been measured for inelastic scattering of 13–24 MeV alpha particles from ^{186,188,190,192}Os. Data have been obtained for 0⁺, 2⁺, 4⁺, 2⁺' states in ^186,188,192Os and for 0⁺, 2⁺ states in ¹⁹⁰Os. Charge and mass quadrupole deformations, β₂^c and β₂^N, were deduced from coupled-channels analysis of the 2⁺ data. No simple model could provide good fits to the 4⁺ data over the entire energy range but the very deep interference minima observed establish the charge and mass hexadecapole moments, β₄^c and β₄^N, to be negative. The energies of the interference minima for the 4⁺ states could be reproduced by coupled-channels calculations only if large differences in β₄^c and β₄^N were allowed. Data for the (J, K)^π = (2, 2)⁺ states are inconsistent with an asymmetric rotational model.     

Transition densities between the 01+, 21+, 41+, 02+, 22+, 11− and 31− states in 12C derived from the three-alpha resonating-group wave functions

All the multipole transition densities between the seven T = 0 states in ¹²C are calculated with the use of the microscopic 3α resonating-group wave functions which are obtained by dynamically solving the 3α relative motion with the total antisymmetrization taken into account exactly. The observed elastic and inelastic electron scattering form factors for the transition to the 2₁⁺, 4₁⁺, 0₂⁺, 1₁^?and 3₁^? states are well reproduced with no additional effective charge. The existence of a deformed intrinsic state for the 0₁⁺, 2₁⁺and 4₁⁺states is deduced by the analysis of the transition densities between them which are derived by the weak-coupling-type 3α wave functions; the intrinsic density distribution is illustrated. The monopole density distribution of the 0₂⁺, 2₂⁺ and 1₁^?, states is found to be much longer ranged than that of the 0₁⁺, 2₁⁺ and 4₁⁺ states; the 3₁^? state case is intermediate. On the basis of the transition densities between the 0₁⁺, 2₁⁺, 0₂⁺ and 2₂⁺ states, analysis is made of the transition between the shell-like states and the molecule-like states with a large spatial-structure change. Specific, effective nucleon-nucleon interactions are folded into the transition densities here obtained. The evident dependence of the radial shape of the folded nucleon-¹²C form factors on the choice of the interactions and the multi-step form factors for the excitation of the 0₂⁺, 1₁^? and 3₁^? states are discussed.     

Secondary ion emission under the bombardment of Si by multiply charged Si q+ ions

The spectra of secondary ion emission under the bombardment of a B-doped Si target by multiply charged Si ^q+ ions (q = 1?C5) have been studied in the energy range of 1 to 10 keV per unit of charge. A multifold increase in the yield of secondary cluster Sk _n ⁺ ions, multiply charged Si ^q/+ ion (q = 1?C3), and H⁺, C⁺, B⁺, Si₂N⁺, Si₂O⁺ is observed as the charge of the multiply charged ions increases. The increase in the yield of secondary ions with increasing charge of the multiply charged-ion charge is most significant for ions with relatively high ionization potentials.     

High-resolution infrared spectra of OOO ozone isotopomer in the range 900-5000 cm: line positions

Continuing the systematic study of ozone high-resolution infrared spectra, we present in this paper the measurements and analyses of line positions for the ¹⁸O¹⁶O¹⁸O isotopomer. In the range 900-5000 cm⁻¹, corresponding to the observed spectra, 15 bands are analysed: ν₁, ν₃, ν₂+ν₃, ν₁+ν₂, 2ν₃, ν₁+ν₃, 2ν₁, ν₂+2ν₃, ν₁+ν₂+ν₃, 3ν₃, 2ν₁+ν₃, ν₂+3ν₃, ν₁+3ν₃, ν₁+ν₂+3ν₃, and 5ν₃. As in the case of ¹⁶O₃, ¹⁸O₃, and ¹⁶O¹⁸O¹⁶O, the analysis of these bands is performed using effective rovibrational Hamiltonians for nine polyads of interacting upper vibrational states. To correctly reproduce all observed transitions, we have to account for resonance perturbations due to 13 “Dark” states: (0 3 0), (0 4 0), (2 1 0), (0 3 1), (1 0 2), (0 4 1), (1 1 2), (3 1 0), (0 3 2), (0 0 4), (3 2 0), (0 1 4), and (0 4 2). We present the range of observed transitions, the results for spectroscopic parameters (vibrational energy levels, rotational and centrifugal distortion constants, and resonance coupling parameters), as well as the statistics for rovibrational energy levels, calculations and measurements. A comparison of observed band centres with those predicted from an isotopically invariant potential function is discussed. The RMS deviation between predicted and directly observed band centres is ≈0.03 cm⁻¹ up to 3000 and ≈0.25 cm⁻¹ for all 16 bands up to 5000 cm⁻¹.     

Electric properties of levels of 156Dy rotational bands

The nonadiabaticity of E0 transitions from 0 ₂ ⁺ states and 2 ₁ ⁺ bands in ¹⁵⁶Dy is examined within a phenomenological model that takes into account the mixing of K ^π = 0 ₁ ⁺ , 0 ₂ ⁺ , 0 ₃ ⁺ , 2 ₁ ⁺ states and 1⁺-bands. It is shown that the nonadiabaticity of E0 transitions is due primarily to the mixing of 0 ₂ ⁺ and 0 ₃ ⁺ bands.     

Tests of interacting boson model wave functions from measured gyromagnetic ratios of states in the even Os isotopes

The gyromagnetic ratios of the 2₁⁺, 2₂⁺, and 4₁⁺ states in ^188,190,192Os were experimentally measured. It is shown that the hamiltonians of standard interacting boson models (IBM-1 and -2) fit to level spectra and B(E2) rates fail to account for either the intra-nucleus or mass-dependent g-factor variations of these states in these Os isotopes.     

Meson-photon transition form factors and resonance cross-sections in e+e− collisions

Meson-photon-photon transition form factors for S-, P-, and D-wave states are calculated, the meson being treated as a non-relativistic heavy-quark-antiquark pair. The full dependence on both photon virtualities is included. Cross-section formulas for charge-conjugation even mesons with J^p = 0⁻, 0⁺, 1⁺, 2⁺, and 2⁻ in electron-positron collisions are presented and numerical results for LEP energies are given. In particular, we find two-photon event rates for χ_c1, η_c(2S), and η_b(1S) within reach of LEP.With minor modifications to incorporate SU(3)-flavour breaking we estimate rates for 18 light mesons as well, based on the observation that their two-photon decay widths agree remarkably well with measured data. Finally we point out that e⁺e⁻ cross sections for 1⁺ states do not vanish at low Q², the Landau-Yang suppression factors of the two-photon cross sections being compensated by the photon propagators.     

The binary and ternary fission of thorium,lead and platinum induced by 12.2 GeV protons

We have investigated the decay of^123g+mIn to excited states of¹²³Sn.¹²³In was produced by the¹²⁴Sn(y,p)¹²³In reaction on an enriched SnO₂ target. The isomeric transition to the¹²³In ground state was not observed. In the beta decay of^123m In excited states at 24, 150.9, 920.5, 1194, 2621, 3151, 3256 and 3306 keV in¹²³Sn withJπ values 3/2⁺, 1/2⁺, (5/2⁺), 5/2⁺, 1/2⁺, (1/2⁺, 3/2⁺), 3/2⁺ and (l/2⁺, 3/2⁺), are fed. In the β decay of the¹²¹In ground state only the 7/2⁺ level at 1154 keV in¹²³Sn is observed.     

Two-nucleon production of hyperons and the search for strange dibaryons

The double charge exchange reaction³He(K^?,π ⁺)Xn was studied at 870 MeV/c. In the X missing mass range below the sigma-nucleon production threshold (2130 MeV/c²), events were detected which can be attributed to the two-nucleon process pp(K^?,π ⁺)λn. This reaction and mass range also offers good prospects for finding theI=1/2,l=1 (¹ P₁) spin-singlet dibaryon D_s suggested as the lowest massS=?1 dibaryon in the MIT Bag Model. Although the existence of the D_s is not ruled out by the present data, there is no need to invoke such an object to account for the observed events below σ production threshold. We show that the cross section level for these events is compatible with a dominant two-nucleon mechanism K^?p→π ⁰λ,π ⁰p →π ⁺n. We also offer an interpretation of the recent (K^?,K⁺) data on nuclear targets from Iijimaet al., which display a broad peak centered around a K⁺ momentum of 600 MeV/c. We find that the two-nucleon mechanism K^?N →πY,πN→K⁺Y produces cross sections which are at least an order of magnitude smaller than those observed, and we suggest that the one nucleon process K^?p →Φλ, followed by the decayΦ → K⁺K^?, accounts for the data.     

Multipole mixing ratios of transitions in Te

Gamma-gamma directional correlation measurements were made on nine transitions in ¹²⁴Te with a NaI(Tl)-Ge(Li) detector arrangement and multichannel analysis. The multipole mixing ratios obtained were δ(646) = 0.000±0.001, δ(714) = 1.5_−0.3^+0.6, δ(723) = −3.3±0.2, δ(1437) = 3.7_−2.0^+2.7, δ(1489) = −3.4_−1.5^+0.9, δ(968) = −0.03_−0.05^+0.06, δ(1368) = −0.045±0.090, δ(1045) = 0.041_−0.041^+0.047, δ(1691) = −0.02±0.01, and δ(2091) = 0.00_−0.03^+0.02. The first δ is M3/E2, the next three are E2/M1, and the last five are M2/E1. The retardation (a factor of approximately 50) of the crossover to cascade transitions from the 2039 keV, third 2⁺ level to the second and first 2⁺ levels is essentially the same for both the M1 and E2 components. In addition, spin and parity assignments of 2⁺ were made for the 2039 and 2092 keV levels.     

Investigations on field desorption products from silver surfaces by mass spectrometry

Field evaporation of silver and field desorption of silver surface compounds were investigated by analysing positive ions with a mass spectrometer. In particular, the well known adsorption states of oxygen, and further the interactions of H₂O, NH₃, H₂, CO and CH₄ were measured in the field ion mass spectrometer under steady state fields of > 0.1 V/Å with a sensitivity of < 0.1 ions s^?1 and at temperatures between 80 °K and 425 °K. Although oxygen is usually chemisorbed at Ag surfaces, no AgO⁺, AgO⁺₂ or other Ag-O compounds could be detected as positive ions, Ag⁺ and O₂⁺ are the only observed ions at best image fields in oxygen up to fields of field evaporation of Ag⁺(≈ 2.2 V/Å). Even after the actual adsorption of oxygen with zero-field (6 × 10⁵ Langmuir at 10^?3 Torr) at 323 °K and 473 °K and subsequent application of the desorption field at 210°K no silver-oxygen compounds were found in positive ionic form. Small quantities of AgO⁺ and AgO⁺₂ were only formed — besides Ag(H₂O)_x⁺ complexes — if atomic oxygen was supplied by the field induced dissociation of water.Gases which do not adsorb on silver under zero-field conditions (H₂, CO, CH₄, N₂) yield the ions Ag(H₂)_n, Ag(CO)_n⁺, n=1, 2; AgCH₄⁺, AgN₂⁺. The situation with H₂O and NH₃ is more complicated: Molecular ions [Ag(H₂O)_n]⁺·mH₂O, n=1,…, 4, m=1,…, 8 and [Ag(NH₃)_n]⁺·mNH₃, n=1, 2, m=1,…, 6 are found besides Ag⁺.From the temperature and field dependence conclusions are drawn about the mechanisms of evaporation and formation of ionic surface complexes. The activation energies of evaporation of Ag⁺ are found to depend on the square root of the field strength. In general, the generation of surface compounds can be described by field induced reactions rather than usual gas adsorption.