Elastic scattering of 3He and α-particles of 16 and 19.5 MeV from several nuclei between 40Ca and 64Zn

Elastic scattering of 19.47 MeV ³He particles by ⁴⁸Ti, ⁵²Cr, ⁵⁵Mn, ⁵⁸Ni, ⁶⁴Zn and ¹³⁸Ba has been observed over an angular range from 20° to 170°. The smooth angular distributions obtained have been analysed by DWBA calculations using three different six-parameter Woods-Saxon potentials. The α-elastic scattering has been measured at 15.98 MeV from ⁴²Ca, ⁴⁸Ti and ⁵²Cr and at 19.47 MeV from ^40,42Ca, ^48,50Ti, ^52,53Cr, ⁵⁵Mn and ^58,60Ni. The angular distributions of the titanium and chromium isotopes have been approximately fitted by average four-parameter potentials searched for different families of parameters with V ∼ 60, 90, 140 and 180 MeV.     

Elastic scattering of α-particles on 10B for Eα = 5–30 MeV

The elastic scattering of α-particles on ¹⁰B has been measured in the energy interval between 5 and 30 MeV. At forward angles a diffraction pattern is observed in the energy range from 12 to 30 MeV, while at backward angles a strong rise of the cross section is seen.The diffraction pattern is interpreted in a Regge-pole diffraction model. The measured behaviour of the cross section at backward angles may be attributed to l-poles in the partial-wave scattering amplitude corresponding to a partial-wave resonance or to angular momentum mismatch between the elastic and absorption channels.     

Surface modification of Makrofol-DE induced by α-particles

In the present work, Makrofol DE samples were irradiated with different doses of alpha particles. The optical and mechanical modifications in the alpha-irradiated Makrofol samples as a function of alpha irradiation time have been investigated. Different characterization techniques, UV–vis spectroscopy, photoluminescence spectroscopy and Vickers micro hardness tester have been used. UV–vis spectra of bombarded samples reveal that the optical absorption increases with increasing the irradiation time. The direct and indirect optical band gap was found to decrease from 3.4 and 2.81?eV for pristine sample to 3.1 and 2.35?eV for that bombarded with alpha particles at the highest irradiation time (15?h), respectively. The number of carbon atoms per conjugated length (N) and the number of carbon atoms per cluster (M) have been estimated. An increase in both N and M with increasing the irradiation time was noticed. A remarkable decrease in PL intensity with increasing the alpha irradiation time was observed. This decrease is attributed to ion beam-induced change in molecular structure and/or defects in the modified layer. The surface hardness for unmodified and modified polymeric material has been studied.     

Nuclear forward scattering of synchrotron radiation from unmagnetized α-57Fe

Nuclear foward scattering of synchrotron radiation from magnetically polycrystalline and partly magnetized -⁵⁷Fe foils has been observed. The forward scattering amplitude in both cases is calculated. The results allow the interpretation of the time spectra from samples which are magnetically polycrystalline or exhibit an unidirectional magnetic texture.     

Energy loss and range of α-particles in different metallic foils

ABSTRACT

The energy loss and range of 5.486?MeV α-particles in Tb, Ta and Au metallic foils is measured, through transmission technique. These measured values are compared with the corresponding computed values adopting commonly used theoretical/semi-empirical formulations (Grande and Schiwietz (CasP 5.2 code), Northcliffe and Schilling, Benton and Henke, ICRU-49 report (ASTAR code) and Ziegler et al. (SRIM-2013.00 code)), with the intention to check the accuracy of the considered formulations.     

Precision measurement of the weak mixing angle in Møller scattering

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (M?ller) scattering: A(PV) = [-131 +/- 14(stat) +/- 10(syst)] x 10(-9), leading to the determination of the weak mixing angle sin2(thetaW(eff) = 0.2397 +/- 0.0010(stat) +/- 0.0008(syst), evaluated at Q2 = 0.026 GeV2. Combining this result with the measurements of sin2(thetaW(eff) at the Z0 pole, the running of the weak mixing angle is observed with over 6sigma significance. The measurement sets constraints on new physics effects at the TeV scale.     

Elastic scattering of α-particles on10B forEα = 5?50 MeV

Experimental data of the elastic scattering of-particles on¹⁰B forE = 30–50.6 MeV are presented. They are analysed together with the data of a previous measurement forE = 5–30 MeV in the frame of the optical model including spin-orbit coupling. The interaction radii of the-¹⁰B-systems are determined with the Inopin-Ericson model forE = 5–50 MeV. The mean free path of-particles in¹⁰B is calculated.     

A new unified theory for scattering of a bounded acoustic beam from a liquid-solid interface near the Rayleigh angle

For scattering of a bounded acoustic beam from a liquid-solidinterface,the principal difficulty comes from the treatment of the plane wave reflec-tion coefficient.In the Present paper,following the Singularity Expansion Method,the reflection coefficient is expanded into the sum of an analytic function(constant1)and the principal part of the Laurent expansion in the neighborhood of theRayleigh pole.The scattered field is now evaluated by a double integral in thewavenumber and interface planes.The constant 1 produces a rigid boundary geo-metrical reflected beam,and the expansions at the Rayleigh poles yield the leakyRayleigh waves.It is particularly proved that the residues of the poles are nearlyproportional to the imaginary parts of the poles for most liquid-solid interfaces.Therefore,the complex pole may determine the whole behavior of the leakyRayleigh wave,including the excitation and reradiation efficiencies.For thebackscattered field,since the negative Rayleigh pole plays a major role,a back-ward l     

Effective range analysis of low-energy α-α scattering

The experimental S-, D- and G-wave phase shifts for the scattering of alpha particles from the helium nucleus are analysed by means of the hard-core effective range formula. It is found that an effective hard-core radius can be defined which takes approximately the same value (1.7 fm) for all three partial waves. The width of the ground state of beryllium is found to be 6.14 ± 0.04 eV. This compares favourably with the experimental value of 6.8 ± 1.7 eV. The justification for the use of a hard core in the α-α interaction is given by a suggested modification to the resonating group method. Effective range formulae for scattering by Coulomb and short-range potentials without a hard core are also derived.     

A study of electron impact excitation of molecular oxygen at a scattering angle of 180°

Excitation of molecular oxygen by electron impact has been observed at the backward scattering angle of 180°. For these studies a new solenoid system with a conical geometry has been designed to implement the angle-changing technique. Energy loss spectra have been measured to deduce differential cross-sections for vibrational excitation of the X³Σ_g⁻ ground state and excitation of the a¹Δ_g state at 180°. Excitation of the b¹Σ_g⁺ state has not been observed at 180° in agreement with the theoretically predicted selection rule Σ⁻←↦Σ⁺ at that angle.     

Positive deviation from debye‘s theory in small—angle x—ray scattering

The small-angle x-ray scattering (SAXS) resulting from a non-ideal two-phase system having sharply defined phase boundaries but with micro-fluctuations of electron density within any phase shows a positive deviation from Debye's theory. We have found a simple method suitable for fitting the slit-smeared SAXS data and correcting the positive deviation. The validity of this procedure is tested on porous ZrO_2 xerogel prepared using the sol-gel process.     

The effect of the irradiation of germanium with α-particles on the recombination of current carriers

A study was made of the effect of irradiation with -particles on surface recombination on germanium. An approximative evaluation of the results showed that the position of the energy level of the recombination centre produced by irradiation lies near to the upper edge of the valence band or the lower edge of the conduction band. A value of roughly 3. 10^–12 cm² was obtained for the effective recombination surface produced by the absorption of one -particle.     

Single- and double-electron charge transfer in collisions of α-particles with hydrogen molecules

Total, partial, and angular differential cross sections of single- and double-electron charge transfer in collisions between α-particles and hydrogen molecules in the ground state in the interval of collision energies from 3 to 80 keV have been calculated. New data for charge transfer cross sections can be used for simulations and spectroscopy of α-particles in thermonuclear diverter plasma of nuclear reactors.     

Nuclear matter sizes and isoscalar octupole transition rates of204,206,208Pb from 104 MeV α-particle scattering

Differential cross sections for elastic and inelastic scattering of 104 MeVα-particles from^204,206,208Pb were measured with high angular accuracy. The experimental results were analysed on the basis of a semimicroscopic folding model in order to determine the matter distributions at the nuclear surface and the transition densities. Using phenomenological parametrizations of the densities the analyses of elastic scattering yield rms radii of 〈r ²〉^1/2=5.55±0.06 (²⁰⁴Pb), 5.57±0.06 (²⁰⁶Pb), 5.63±0.05 (²⁰⁸Pb) fm. Various sensitivities affecting the results were studied. From the inelastic cross sections for the 3 ₁ ^? -states octupole transition probabilities and transition radii were derived by using different methods proposed in literature.