TheL 2-L 3 Coster-Kronig transition probability at Z=96

The total probabilityf ₂₃ for theL ₂–L ₂ Coster-Kronig transition atZ=96 was measured by theL _α?K _α1,2 x-ray coincidence technique with a²⁴⁹Cf radioactive source. The value at Z=96 was found to bef ₂₃=0.209±0.022 (2σ, 95% confidence). This result is in agreement within the 2σ error limits with previous measurements which range from 0.188 to 0.226, and this spread cannot be reduced by improvements in the experimental technique primarily because of the large correction required for the effect of nuclear cascading in²⁴⁹Cf decay.     

The dynamics of traded value revisited

We conclude from an analysis of high resolution NYSE data that the distribution of the traded value f_i (or volume) has a finite variance σ_i for the very large majority of stocks i, and the distribution itself is non-universal across stocks. The Hurst exponent of the same time series displays a crossover from weakly to strongly correlated behavior around the time scale of 1 day. The persistence in the strongly correlated regime increases with the average trading activity 〈f_i〉 as , which is another sign of non-universal behavior. The existence of such liquidity dependent correlations is consistent with the empirical observation that σ_i∝〈f_i〉^α, where α is a non-trivial, time scale dependent exponent.     

Theory of thermal remagnetization of permanent magnets

A self-consistent mean-field theory explaining the thermal remagnetization (TR) of polycrystalline permanent magnets is given. The influence of the environment of a grain is treated by an inclusion approximation, relating the field inside the grain to the local field outside by means of an internal demagnetization factor n. For the switching fields and the fluctuations of the local fields around the mean field, Gaussian distributions of widths σ_s, and σ_f, respectively, are assumed. The isothermal hysteresis curve, the recoil curves, and the TR dependent on the model parameters n, σ_s, and σ_f are calculated. Furthermore, the influence of the initial temperature and the strong dependence of the TR on the demagnetization factor of the sample are studied, and it is shown that for reasonable parameter sets TR effects up to 100% are possible. The theoretical results correspond well with the experimental situation.     

New experimental data on the formation of the symmetric fission mode

The variances of the fission-fragment mass distributions,σ _M ² , were measured for (α,f) and (³He,f) reactions in the interval between Os and At. The analysis of the experimental data suggests that the properties of symmetric fission aroundx-0.7 are mainly determined by the barrier passing stage. This conclusion is in discrepancy with results of dynamic calculations.     

Kinematical and dynamical considerations of muon capture by deuteron

Proton inducedL X-ray yields from thick targets of In, Sn, Nd, Dy, Pt and Au have been measured in the energy range 1–3 MeV. Cross-sections have been derived from these thick target yields and are compared with the predictions of non relativistic PWBA, BEA and CBEA theories. The ratios σ_Lα/σ_Ll, σ_Lα/σ_Lβ and σ_Lα/σ_Lγ are also presented.     

Light-Front Quantization of Conformally Gauge-Fixed Polyakov D1-Brane Action in the Presence of a Scalar Axion Field and an U(1) Gauge Field

Light-front quantization of the conformally gauge-fixed Polyakov D1 brane action in the presence of a constant background scalar axion field C(τ, σ) and an U(1) gauge field A _α (τ, σ) is studied. The axion field C and the U(1) gauge field A _α , are seen to behave like the Wess–Zumino (WZ) fields and the term involving these fields is seen to behave like a WZ term for this action.     

Multifractal analysis of ITO thin films prepared by electron beam deposition method

In this work, we developed the multifractality and its formalism to investigate the surface topographies of ITO thin films prepared by electron beam deposition method for various annealing temperatures from their atomic force microscopy (AFM) images. Multifractal analysis shows that the spectrum width, Δα (Δα = α_max − α_min), of the multifractal spectra, f(α), can be used to characterize the surface roughness of the ITO films quantitatively. Also, it is found that the f(α) shapes of the as-deposited and annealed films remained left hooked (that is Δf = f(α_min) − f(α_max) > 0), and falls within the range 0.149-0.677 depending upon the annealing temperatures.     

A kinetic study of the thermal decomposition process of potassium metabisulfite: Estimation of distributed reactivity model

The thermal decomposition kinetics of potassium metabisulfite was studied by thermogravimetric (TG) and differential thermogravimetric (DTG) techniques using non-isothermal experiments. The apparent activation energy (E_a) is determined using the differential (Friedman) isoconversional method. The results of the Friedman's isoconversional analysis of the TG data suggests that the investigated decomposition process follows a single-step reaction and the observed apparent activation energy was determined as 122.4±2.1 kJ mol⁻¹. A kinetic rate equation was derived for the decomposition process of potassium metabisulfite with contracting area model, f(α)=2(1−α)^1/2, which is established using the Malek's kinetic procedure. The value of pre-exponential factor (A) is also evaluated and was found to be A=1.37×10¹² min⁻¹. By applying the Miura's procedure the distributed reactivity model (DRM) for investigated decomposition process was established. From the dependence α versus E_a, the experimental distribution curve of apparent activation energies, f(E_a), was estimated. By applying the non-linear least-squares analysis, it was found that the Gaussian distribution model (with distribution parameters E₀=121.3 kJ mol⁻¹ and σ=1.5 kJ mol⁻¹) represents the best reactivity model for describing the investigated process. Using the Miura's method, the A values were estimated at five different heating rates and the average A values are plotted against E_a. The linear relationship between the A and E_a values was established (compensation effect). Also, it was concluded that the E_a values calculated by the Friedman's method and estimated distribution curve, f(E_a), are correct even in the case when the investigated decomposition process occurs through the single-step reaction mechanism.     

Non-diffractive Pomeron renormalization,multiplicities, and the topological expansion

The renormalization of the Pomeron due to nondiffractive K$\text{K}$, B$\text{B}$ production thresholds is considered within a simple generalization of the Chew-Rosenzweig multiperipheral realization of Veneziano's topological expansion. The results are consistent with the existence of both the “low-energy” bare Pomeron with intercept $\text{α=0.85}$ and Gribov bare Pomeron with intercept above one. The vacuum exchange part of 2σ_KN?σ_πN basically rises with energy. Qualitatively correct features of shrinkage and breaks of $\text{d}\text{σ}\text{d}\text{t}$ emerge. The multiplicity of product clusters (n) increases with energy faster than 1ns and agrees with experiment for an average number of particles per cluster of 3–4. Independently of our model the Harari-Freund multiperipheral realization of the topological expansion is shown to be in serious difficulty with multiplicities, requiring around 20 particles per cluster.     

On the fusion cross section for 16O + 12C

The total fusion cross section σ_f for ¹⁶O + ¹²c.m. has been measured in 250 keV steps between 17 and 28 MeV c.m. energy via γ-ray techniques. Individual yields for 10 nuclides in the evaporation chain were determined. The oscillations in σ_f, which agree in gross structure but not in detail with previous work, appear to be most closely associated with reactions leading to ²⁰Ne. It is observed that the reaction yield is >80% dominated by nuclides having at least one α particle in the evaporation chain.     

Radiative lifetimes and tensor polarizabilities of 1s4f 1 F and 1s5f 1 F level of He I

He atoms have been excited by Ne⁺ ion impact and the depolarization of the fluorescence lines at 668 nm and 492 nm by magnetic and electric fields has been studied. The Ne⁺ ion energy could be chosen such that pure cascade level crossing signals were observed. From the widths of magnetic depolarization signals the radiative lifetimes τ(1s4f ¹ F)=74(2) ns and τ(1s5f ¹ F)=133(5) ns have been determined. By investigating the electric field splitting of the magnetic depolarization signals the tensor polarizabilities ¦α _ten(1s4f ¹ F)¦=0.58(1) kHz/(V/cm)² and ¦α _ten(1s5f ¹ F)¦=4.2(1) kHz/(V/cm)² have been deduced. From the latter value a mean frequencyv(1s5g?1s5f)=14.4 GHz of the transitions between the levels of the 1s5f configuration and those of the 1s5g configuration has been derived.α _ten(1s4f ¹ F) depends sensitively on the singlet-triplet mixing in the 1s4f configuration and thus a mixing coefficient could be deduced for this configuration.     

Thermal neutron induced α-particle reaction on64, 65, 67Zn and77Se

The (_n th,α) reaction spectroscopy was done on^{64, 65, 67}zn and⁷⁷Se at the 87 m curved thermal neutron guide of the Grenoble high flux reactor. In each of the⁶⁴Zn(n, α)⁶¹ Ni and⁶⁷ Ni(n, α) ⁶⁴Ni reactions, one line showed up corresponding to anα-particle transition to the first excited state in⁶¹Ni and⁶⁴Ni withσ _α1=11±3 μb and 159±20 μb respectively. In the case of the radioactive⁶⁵Zn(T _1/2=244d) nucleus, two lines showed up corresponding to the ground state and the first excited state transitions in⁶²Ni with large values ofσ _α0=1.0±0.1b andσ _α1=1.0±0.1b. For the⁷⁷Se(n, α)⁷⁴Ge reaction, the ground state and first excited transitions were present withσ _α0=940±20 μb andσ _α1 = 30±5 μb respectively. The spin-parity (J ^π) of the neutron resonance contributing at thermal energy are discussed.     

Beta decay of polarized Λ hyperons III. Correlations in the Λ centre-of-mass system and the proton recoil spectrum

From the analysis of 817 kinematically resonstructed beta decay events of polarized Λ hyperons for the coefficient α_ν of the neutrino correlation with respect to the Λ spin, α_ν = 0.89 ± 0.08, for the coefficient α_T of the T-odd correlation σ_Λ(p_e × p_ν), α_T = ?0.14 ± 0.13. The proton recoil spectrum yields …g₁/f₁… = 0.64 ± 0.06.     

Total reaction cross section from the interaction of 4He ions with 28Si at 10–30 MeV

New results have been obtained for the energy dependence of the total reaction cross section σ _R of ⁴He on ²⁸Si in the energy range E _α ≤ 30 meV.     

Total cross sections for 4,6He + 28Si reactions measured at 10–28 MeV/A

New results on the energy dependence of the total cross section (σ _R) for ⁶He scattering on ²⁸Si in the incident energy range 10–28 MeV/A are obtained. The α-particle-production cross sections for the ²⁸Si(⁶He, ⁴He)X channel are measured as well. The secondary beam of ⁶He with an intensity of up to 5×10⁴ particle/s was generated by bombarding a thick beryllium target with ～32-MeV/A ⁷Li ions. In the energy region below 17 MeV/A, σ _R increases sharply. The experimental dependences of the total cross sections are compared with the results of σ _R calculations using the double-folding potential within the optical model. The energy dependence of σ _R for ⁶He differs from that for the neighboring nuclei, which can be associated with the structural features of the former nucleus. The energy spectra of α particles produced in the ⁶He interactions with silicon indicate two mechanisms of their production: transfer reaction and ⁶He breakup in the field of the ²⁸Si nucleus.     

Study of the reaction238U (α, α′f) atE α=480 MeV

The excitation function of the fission probability P _E E _x) for²³⁸U has been measured in the reaction²³⁸U(α, α′ f) at 480 MeV bombarding energy. The reaction mechanism of this reaction is discussed for excitation energies belowB _nf , the threshold for second chance fission, and aboveB _nf up toE _x =37 MeV. In comparing with results from fission induced by photons and by particle transfer reactions the (α, α′f) reaction gives too low values for the fission probabilityP _f at excitation energies well aboveB _nE . The role of the quasi-elastic knock-out process in this reaction is discussed.     

Measurement of fast neutron induced fission cross section of thorium using Lexan plastic track detector

Fission-track registration characteristics of Lexan solid state nuclear track detectors have been used to measure the fast neutron induced fission cross section of²³²Th. The fast neutrons (?14.2MeV) were produced with the help of an AN-400 model Van-de-Graaff accelerator at Banaras Hindu University laboratory using³H(²H,n)⁴He reaction and were used to irradiate the fissile target deposited on the plastic detector. The track densityT, registered on the plastic detector is related to the fission cross sectionσ _f, through the relationT=knσ _føt wheren is the number of fissile atoms per cm² in the deposit, ø is the neutron flux,k is fission track registration efficiency andt is the time of irradiation. The fission cross sectionσ _f of²³²Th, relative to the well measured fission cross section of²³⁸U, was found to be 0.36±0.04 barn.     

Particle size dependence of exchange-bias and coercivity in CuO nanoparticles

For CuO nanocrystals of size 6.6-37 nm, the exchange bias H_eb and coercivity H_c are measured at 5 K in zero-field-cooled (ZFC) and field-cooled (FC at 50 kOe) samples and their variations investigated as a function of particle size D. The similar 1/D variations observed for the difference coercivity ΔH_c=H_c(FC)−H_c(ZFC) and the interfacial exchange energy Δσ=H_ebM_fD are discussed in terms of the ferromagnetic magnetization M_f being produced by the uncompensated surface Cu²⁺ spins in the otherwise antiferromagnetically ordered CuO nanoparticles. This leads to the observation that the experimentally measured ΔH_c provides a good measure of Δσ in nanoparticle systems, with H_eb/ΔH_c varying as 1/M_fD.     

Photoemission of adsorbed CO and H2O on Pt: Valence band studies

In this paper, using monochromatic He and Ne discharge lines, we report the ultraviolet photoemission results for CO and H₂O adsorbed on a Pt crystal. For chemisorbed CO, we use the energy dependence of the photoionization cross section to deduce that the 5σ?1π splitting is approximately 1 eV and that the 5σ is located at about ?8.1 eV while the 1π is at ?9.1 eV. The distribution of metal electrons changes in two ways upon CO chemisorption: a d character peak is found at ?4 to ?5 eV and emission at E_f is strongly depleted. For the weakly adsorbed water molecule, we find preferential attenuation of Pt states near E_f that has heretofore been observed for strongly chemisorbed systems.