First Penning trap mass measurements beyond the proton drip line

The masses of six neutron-deficient rare holmium and thulium isotopes close to the proton drip line were determined with the SHIPTRAP Penning trap mass spectrometer. For the first time the masses of the proton-unbound isotopes 144,145Ho and 147,148Tm were directly measured. The proton separation energies were derived from the measured mass values and compared to predictions from mass formulas. The new values of the proton separation energies are used to determine the location of the proton drip line for holmium and thulium more accurately.     

Two-pion production in proton-proton collisions with a polarized beam

The two-pion production reaction pp → ppπ⁺π⁻ was measured with a polarized proton beam at T _p ≈ 750 and 800MeV using the short version of the COSY-TOF spectrometer. The implementation of a delayed-pulse technique for Quirl and central calorimeter provided positive π⁺ identification in addition to the standard particle identification, energy determination as well as time-of-flight and angle measurements. Thus all four-momenta of the emerging particles could be determined with 1–4 overconstraints. Total and differential cross-sections as well as angular distributions of the vector analyzing power have been obtained. They are compared to previous data and theoretical calculations. In contrast to predictions we find significant analyzing-power values up to A _y = 0.3. The data taken in the energy region of the excitation of the Roper resonance confirm that its dominant ππ decay channel is N ^* → Nσ.     

Structure and superconductivity of La1.8Sr0.2CuO4 and multi-phase Y1.2Ba0.8CuO4 under high pressure

Superconducting La_1.8Sr_0.2CuO₄ has been investigated under pressure. Its resistiveT _c -midpoint was found to be 37 K at ambient pressure. It inductively determinedT _c is 33 K monotonically shifting up to 38.4 K at 19.2 kbar. The initial linear increase is 0.295 K/kbar. X-ray investigations in a diamond anvil revealed no phase transformation of the K₂NiF₄ structure up to about 50 kbar at 300 K, 60 K and 15 K. The bulk modulus of La_1.8Sr_0.2CuO₄ was 1070 kbar at 300 K and 1500 kbar at 15 K. Thec/a ratio decreases and shows pronounced differences between room temperature and low temperature data under pressure. Multi-phase Y–Ba–Cu-Oxide with resistiveT _c -onset of 90 K was investigated under pressure, too. The inductive transition starts at 70 K and is completed at 20 K. The superconducting volume fraction was estimated to be about 2% at 10 K.     

PAC Investigation of Amorphous Ferromagnets

The amorphous ferromagnetic alloy Fe79/B16/Si5 was investigated by PAC. For that the probe atoms ¹¹¹In(¹¹¹Cd) and ^111mCd were implanted at the ISOLDE on-line separator. The distributions of magnetic hyperfine fields were determined. Below the crystallization temperature α-Fe clusters could be observed. For comparison Mössbauer transmission experiments were performed.     

A semi-collocated ocean model based on the SOMS approach

In application to the Gulf of Mexico (GOM), a new DieCAST ocean model, which uses a modified Arakawa ‘a’ grid, and the SOMS model, which uses an Arakawa ‘c’ grid, give remarkably similar results. The new model avoids ‘null space’ problems of the standard ‘a’ grid approach by first using fourth-order interpolations to a ‘c’ grid advection velocity, then applying incompressibility to the result. Accuracy is further improved by using fourth-order pressure gradient approximations at ‘a’ grid locations. Incompressibility with general geometry is satisfied efficiently by a fast-converging iteration with a regular gteometry elliptic solver. Results are compared with satellite-measured r.m.s. sea surface elevation anomaly and detailed front structures, climatological mean thermocline and empirical orthogonal functions and other observations.     

Über die Äquivalenz von Wärme-, Kraft- und Massenquellen

Summary The steady, nonviscous flow in fields with sources of energy, force and mass is investigated under the assumption of small perturbations. The different sources are equivalent in such a way that it is possible to change the sources without changing certain values of the flow field if one does not change certain combinations of the sources. In the same way it is possible to obtain an unchanged drag-coefficient by changing the sources.Herrn Professor Dr.K. Oswatitsch möchte ich für zahlreiche Ratschläge vielmals danken.