Initial State Interaction in the (π+,3p) Reaction on N, Ar and Xe

The pion absorption reaction (π^{+,3 p} ) on Ar was studied at pion energies of 70, 118, 162 and 239 MeV, and on N and Xe at 239 MeV. The 3p cross section with a 50 MeV cut on the missing energy is presented. The existence of an initial state interaction (ISI) component to the reaction was investigated. The portion of the 3p cross section assigned to the ISI process is less than one half and at lower energies significantly so. Received: 11 December 1997     

The particle-hole spectra of 16O and 16N as observed in pick-up reactions from 17O

The reactions ¹⁷O(d, t) ¹⁶O and ¹⁷O(d, τ)¹⁶N have been investigated at E_d = 52 MeV. Energy spectra of tritons and τ-particles have been measured simultaneously up to excitation energies of 22 MeV in ¹⁶O and 10 MeV in ¹⁶N, respectively. Spectroscopic factors have been obtained by a DWBA analysis of the measured angular distributions. From the comparison of the t- and τ-spectra analog (T = 1) states in ¹⁶O could be identified and the distribution of T = 0 and T = 1 spectroscopic strengths could be deduced. Nearly the total $\text{1}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{1}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ hole strengths have been found and the $\text{1}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{1}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}\text{and}\text{1}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{1}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$ particle-hole multiplets could be located both for T = 0 and T = 1. The average residual interactions in both shell-model configurations turned out to be strikingly different.     

An integral bound for the strain energy in nonlinear elasticity in terms of the boundary displacements

For the displacement boundary value problem in nonlinear elastostatics with zero body force, an integral bound for the strain energy is obtained in terms of theL ₂-norms of the given boundary displacements and their tangential derivatives (assumed sufficiently small). The constants involved depend upon the strain energy density function and upon the geometry of the domain.     

Energieverlust von Elektronen in Aluminium im Energiebereich 20 bis 60 MeV

The energy spectrum of nearly monoenergetic electrons (energy width about 0.3%) was measured with a spectrometer of high resolution (about 0.1%) before and after passing through aluminum absorbers of thicknesses between 0.08 and 5.4 g/cm². The experiments were performed with the energy-analysed beam of the Darmstadt linear accelerator; the energy was varied between 20 and 60 MeV. The most probable energy losses agree with the theory ofSternheimer within the error limits (1.5?2%) for thicknesses smaller than 2 g/cm². The half widths are systematically larger than the values calculated byBlunck andWestphal.     

Measurement of the generalized polarizabilities of the proton in virtual Compton scattering at Q2=0.92 and 1.76 GeV2

We report a virtual Compton scattering study of the proton at low c.m. energies. We have determined the structure functions P(LL)-P(TT)/epsilon and P(LT), and the electric and magnetic generalized polarizabilities (GPs) alpha(E)(Q2) and beta(M)(Q2) at momentum transfer Q(2)=0.92 and 1.76 GeV2. The electric GP shows a strong falloff with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a falloff; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from piN intermediate states.     

Parity-violating electron deuteron scattering and the proton's neutral weak axial vector form factor

We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at backward angles at Q2=0.038 (GeV/c)2. This quantity provides a determination of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A=-3.51+/-0.57 (stat)+/-0.58 (syst) ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also consistent with theoretical predictions.     

Industrial methods for the production of optically active intermediates

Enantiomerically pure amino acids, amino alcohols, amines, alcohols, and epoxides play an increasingly important role as intermediates in the pharmaceutical industry and agrochemistry, where both a high degree of purity and large quantities of the compounds are required. The chemical industry has primarily relied upon established chemical methods for the synthesis of these intermediates, but is now turning more and more to enzymatic and biotechnological fermentation processes. For the industrial implementation of many transformations alternative methods are available. The advantages of the individual methods will be discussed herein and exemplified by syntheses of relevant compounds.     

Parity violation in elastic electron-proton scattering and the Proton's strange magnetic form factor

We report a new measurement of the parity-violating asymmetry in elastic electron scattering from the proton at backward scattering angles. This asymmetry is sensitive to the strange magnetic form factor of the proton as well as electroweak axial radiative corrections. The new measurement of A = -4.92+/-0.61+/-0.73 ppm provides a significant constraint on these quantities. The implications for the strange magnetic form factor are discussed in the context of theoretical estimates for the axial corrections.     

The use of vector-valued martingales in risk theory

A completely dependent risk process with perturbation and phase-type distributed claim sizes is analyzed. Claim arrivals are modeled by a Markovian arrival process. Using a vector-valued martingale, the Laplace transform of the time to ruin is derived algorithmically. The conditional memoryless property of the phase-type distribution yields the distribution of the deficit at ruin as a corollary.