A study of the reactions KN→Σ(1385)π between 0.6 and 1.2 GeV/c

An energy-dependent partial-wave analysis of the reaction $\text{K}\text{N}\text{→Σ(1385)π}$ has been performed in the energy region lying between 1.65 and 1.85 GeV. The resonant amplitudes of seven well known Y¹ resonances have been determined, and used to compute the corresponding (8) ? (10) SU (3) coupling constants.     

Synthesis of an imidazo[1,2-c]pyrimidine analog of a thiamine antagonist coccidiostat and a comparison of several methods for the preparation of imidazo[1,2-c]pyrimidines

Several methods for the preparation of imidazo[1,2-c]pyrimidines are presented. Compound 12 was prepared from 11 and chloroacetaldehyde in water using a buffer to control pH. Compound 12 was converted in two steps to 14 , the etheno bridged analog of the coccidiostat 1. Several methods were used to prepare 8-phenylimidazo[1,2-c]pyrimidine ( 16 ). In terms of yield the best method was the reaction of the aminopyrimidine 15 with chloroacetaldehyde in acetone and in the presence of calcium carbonate as an acid scavenger. Reaction of the 4-chloro-pyrimidine 19 with aminoacetaldehyde diethyl acetal gave 16 directly in modest yield.     

Transition quadrupole moments of superdeformed states in194Pb

Lifetimes of superdeformed states in¹⁹⁴Pb were measured by the Doppler-shift attenuation method. Quadrupole moments around 20 eb, that are constant over the observed frequency range, are derived. The results rule out large centrifugal stretching effects.     

Fluctuations in synchronously mode-locked dye lasers

We present detailed experimental data on random fluctuations of the pulse properties of a cw rhodamine 6G dye laser synchronously pumped by an acousto-optically mode-locked argon ion laser. It is shown that quantitative information about the fluctuations of the energy, the pulse repetition time and the duration of the pulses can be obtained from the power spectrum of the laser intensity which is measured with the use of an electronic spectrum analyser. This method is capable of revealing small, subpicosecond temporal pulse jitter. We show that the dye laser pulses exhibit an absolute r.m.s. jitter of 20 ps which is induced by the pump laser. The relative jitter in a dual system can be less than 1 ps because well defined correlations of the output fluctuations exist when two lasers are pumped by a common source.     

Significance of intra-cavity power density in synchronous mode-locking of CW-dye lasers

It is shown that there is a well-defined relation between the intra-cavity power density and the temporal structure of ultrashort light pulses generated by a synchronously pumped cw dye laser. To obtain pulses of good quality with high output power the beam cross-section in the lasing medium must be large, because the best performance is achieved at low power density.     

In-beam γ-ray spectroscopy of the neutron deficient 100Ag

Conversion coefficients and conversion ratios of someγ-transitions in²⁰¹Tl and²⁰³Tl were measured by means of simultaneous spectroscopy ofγ-quanta and conversion electrons employing intensity calibrated semiconductor detectors. The experiments aimed at a precision as high as possible within the limits of the experimental methode used. Theγ-transitions were of the typeM 1(+E2). From the measured values the penetration parameters of the internal conversion for theM 1 components (λ) together with the multipol mixing ratios (δ²) were deduced. The necessary theoretical coefficients were taken from the tables of Hager and Seltzer. The results are for the ?-forbidden 331 keV transition in²⁰¹Tl,λ=+4.0±1.0,δ ²=1.78±0.16; for the ?-allowed 361 keV transition in²⁰¹Tl,λ=+0.5±0.5,δ ²=0.02±0.02; for the ?-forbidden 279 keV transition in²⁰³Tl,λ=+ 5.71±0.45,δ ²=1.55±0.08.     

Measurement of the total neutron cross section of 14N and 24Mg

The total neutron cross section of ¹⁴N and ²⁴Mg has been determined for neutron energies between 1.0 and 5.2 MeV. For this purpose, the attenuation of a continuous neutron spectrum in absorbing samples of liquid natural nitrogen and enriched ²⁴Mg has been measured in open geometry with the time-of-flight technique. A time resolution of 0.07 ns/m was achieved. The obtained data improve the knowledge on the cross section of ¹⁴N above 2 MeV and of ²⁴Mg in the total energy range. In the latter, a large number of resonances is observed for the first time.     

Observation of leading particles in pp interactions with large transverse momentum secondaries at the CERN-ISR

Events with a positive particle of large transverse momentum emitted at medium angles have been studied using the split field magnet spectrometer at the CERN-ISR at a c.m. energy of √s = 52.5 GeV. Positive particles with large longitudinal momentum, |x| > 0.5, i.e., leading particles, associated to large p_T events, are analysed.     

Electron microscopic investigation of the molecular mechanism of plastic deformation of polyethylene and isotactic polystyrene crystals

The molecular process involved in the plastic deformation of crystals of linear polyethylene and isotactic polystyrene by necking was investigated by transmission electron microscopy (TEM). The results for the draw ratio, the height, and the shape of the neck and the molecular structure of the deformed material suggest that plastic deformation occurs basically by the unfolding and bending of the molecules in a deformation region only a few nm wide. The observations are at variance with deformation models involving complete unfolding of the molecules or the breaking off of folded-chain blocks and the incorporation of these blocks into the deformed material.     

An efficient step size control for continuation methods

In solving a nonlinear equation by the use of a continuation method one of the crucial problems is the choice of the step sizes. We present a model for the total computational cost of a standard numerical continuation process and solve the problem of optimal step size control for this model. Using the theoretical results as a basis, we develop an adaptive step size algorithm for Newton's method. This procedure is computationally inexpensive and it gives quite satisfactory results compared to some other numerical experiments found in the literature.