George L. Strobel

Excitation of giant multipole resonances L = 1–4 in the 16(p, p') spin-flip transition

Abstract An investigation of inelastic proton scattering to the 2 − 8.88 MeV state in 16 O is presented in an energy range between 23 and 46 MeV. Transition matrix elements are evaluated within the antisymmetrized DW theory. The two-step exchange resonance mechanism is included applying the deformed-potential model. Good agreement with all data is obtained adjusting the coupling constants in a least-square search. The obtained values reflect four pronounced resonances which are identified with giant multipole resonances in 16 O.

Flat-sided rectilinear trough as a solar concentrator: an analytical study

Formulas are derived for the concentration factor and irradiance distribution at the base of the flat-sided linear trough. Performance is affected by the number of reflections the solar rays undergo before reaching the base, the cone apex angle, and the coefficient of reflection. Results are presented graphically in such a way that one can choose the optimum configuration, which is the minimum material required, to achieve a given concentration factor. Practical concentration factors range from 1.5 to 4 depending on the geometry and coefficient of reflection.

Nonlinear superposition rule for Abel's equation

Abstract A nonlinear superposition rule for Abels cubic differential equation involving four particular solutions can be replaced by a superposition rule involving only two particular solutions. Chiellinis restrictions on the particular solutions are found to be satisfied.

The 16O(d, 3He) excitation spectrum

Abstract The 16 O(d, 3 He) excitation spectrum has been calculated in the framework of the Gross-Lipperheide model which explicitly takes into account the effect of residual interactions and the decay of the residual nucleus by particle emission. The reaction mechanism is described by the DWBA for a direct pick-up reaction. The theory is extended to include the higher-order effects of the residual interaction on the self-energy operator, in terms of which the spectral function is expressed. The real part of the self-energy operator is calculated up to the fourth order (2p-3h configurations) in the strength of the residual interaction. The calculation of the self-energy operator up to the second order yields the leading term only for separation energy below 38 MeV. Higher-order effects have already become important for separation energies as low as 10 MeV. The Lemmer-Shakin potential is used for the residual interaction. The calculated spectrum exhibits a shell structure of groups of narrow peaks, which depends very much upon the choice of the absorption potential for the 3 He optical parameters.

Irradiance for skew rays incident upon a trough-like solar collector of arbitrary shape

Abstract A formula is derived for the irradiance at the base of a trough-like solar concentrator for rays incident at any arbitrary angle upon the curved sides of the concentrator. Two angles are required to specify the direction of the incoming rays. It is shown that one of the angles, θ, enters the expression for the irradiance only through the multiplicative factor cos θ and therefore plays the role of the obliquity factor associated with cosine of the angle of incidence for a flat plate collector.

Solar concentrating properties of truncated hexagonal, pyramidal and circular cones

The concentrating properties of specularly reflecting pyramids, hexagons, and circular cones are examined. The concentration factor is determined as a function of the coefficient of reflection and the shape and orientation of the incident sunlight. Reflector designs allowing multiple reflections for both normal and oblique incidence are considered.

A separable nucleon-nucleon potential

Abstract A separable potential for the nucleon-nucleon interaction is presented, assuming form factors of the type g ( k ) = ak L e− bk 2 , where a and b are parameters adjusted to fit the experimental phase shifts. With this formulation, it is possible to reproduce the singlet and triplet scattering lengths and effective ranges as well as the elastic-scattering phase shifts up to 320 MeV for states containing L = 0 components.

Caustic surface analysis for a gradient-index lens

General formulas for the energy flux density and the caustic surfaces formed by light rays propagating in a gradient-index medium are derived. For the radial gradient index of refraction, n2(r)=N20−b2r2, where N0 and b are constants, analytical expressions are presented for the energy density along the ray path in a medium and for the caustic surfaces produced by the medium. As an application, the caustic surfaces formed by collimated light rays incident upon a converging Wood lens are analyzed.

A K-harmonics description of 16O breathing mode

Abstract We calculate the properties of the 16 O breathing mode in a K min K -harmonics calculation. The breathing mode has single particle quantum numbers that are identical to the nucleon quantum numbers in the ground state. We calculate an excitation energy of 27 MeV, and a monopole transition matrix element of 7.21 fm 2 . Six excited monopole states are calculated to be bound in 16 O, with k equal to K min . These states exhaust 90 % of the isoscalar monopole sum rule. The first excited K min state, the breathing mode, exhausts 68 % of the isoscalar sum rule.

A two-step model of pion induced nucleon knockout reactions

Abstract A two-step model is utilized to explain the puzzling isospin dependence of pion induced nucleon knockout reactions. The model treats the pions as strongly absorbed by nuclei. The pion is assumed to interact only once, even in the two-step mechanism. Energy transfer systematics suggest the pion interaction is with a four-nucleon cluster. If so, this helps to explain the surprisingly large pion induced α-knockout cross sections seen recently.