Die Sammlung Cäsar Hirsch

Im Rahmen eines Schwerpunktheftes zu „Provenienz und Restitution“ berichtet Berndt v. Egidy über das Schicksal der Privatbibliothek des jüdischen Arztes Cäsar Hirsch. Die Sammlung wurde nach Hirsch’ Flucht in die Schweiz 1933 von der Gestapo beschlagnahmt und gelangte 1939 in die Universitätsbibliothek Tübingen. Durch die Recherchearbeit des Journalisten Hans-Joachim Lang wurde 1999 bekannt, wo sich die Sammlung befand. Die Universitätsbibliothek bot den Erben von Hirsch in den USA die Rückgabe an, diese entschieden sich dann, die Bücher der Biomedical Library der Universität von Kalifornien zu übergeben. Nachdem die Sammlung verschifft war, meldete sich die Berliner Oberfinanzdirektion, da es sich um eine Doppelentschädigung handele: die Erben von Hirsch seien bereits in den 60er Jahren entschädigt worden. Zum Schluss gibt der Autor einige allgemeine Empfehlungen zur Restitution von Büchersammlungen in Deutschland

Upward Translation of Optimal and P-Optimal Proof Systems in the Boolean Hierarchy over NP

We study the existence of optimal and p-optimal proof systems for classes in the Boolean hierarchy over $\mathrm{NP}$. Our main results concern $\mathrm{DP}$, i.e., the second level of this hierarchy: If all sets in $\mathrm{DP}$ have p-optimal proof systems, then all sets in $\mathrm{coDP}$ have p-optimal proof systems. The analogous implication for optimal proof systems fails relative to an oracle. As a consequence, we clarify such implications for all classes $\mathcal{C}$ and $\mathcal{D}$ in the Boolean hierarchy over $\mathrm{NP}$: either we can prove the implication or show that it fails relative to an oracle. Furthermore, we show that the sets $\mathrm{SAT}$ and $\mathrm{TAUT}$ have p-optimal proof systems, if and only if all sets in the Boolean hierarchy over $\mathrm{NP}$ have p-optimal proof systems which is a new characterization of a conjecture studied by Pudl\'ak

Nuclear surface studies with antiprotonic atom X-rays

The recent and older level shifts and widths in pbar atoms are analyzed. The results are fitted by an antiproton-nucleus optical potential with two basic complex strength parameters. These parameters are related to average S and P wave scattering parameters in the subthreshold energy region. A fair consistency of the X-ray data for all Z values, stopping pbar data and the Nbar-N scattering data has been achieved. The determination of neutron density profiles at the nuclear surface is undertaken, and the determination of the neutron R_{rms} radii is attempted. Uncertainties due to the input data and the procedure are discussed.Comment: 13 pages, 6 tables, 3 figure

Proučavanje jezgre 168Er reakcijom (d, p)

The reaction 167Er(d,p)168Er was measured with 22 MeV deuterons at the angles 15◦ , 30◦ and 40◦ . Up to 2.8 MeV, a total of 78 levels were identified. Measured differential cross–sections are given. The results are compared with previous data, especially from the (n,γ) reaction.Izvršili smo mjerenja reakcije 167Er(d,p)168Er s deuteronima energije 22 MeV, na kutovima 15◦ , 30◦ i 40◦ . Do energije uzbude od 2.8 MeV našli smo 78 stanja. U radu se prikazuju izmjereni diferencijalni udarni presjeci. Rezultati se uspoređuju s ranijima, posebno onima iz mjerenja reakcije (n, γ)

Nuklearna reakcija 103Rh(d,p)104Rh

The 103Rh(d, p)104Rh reaction was measured with 22 MeV deuterons up to 1.8 MeV excitation energy at laboratory angles of 20◦ , 30◦ and 50◦ . The best energy resolution was 3.6 keV. 91 energy levels were observed and the angular momentum transfer was determined.Nuklearna reakcija 103Rh(d,p)104Rh istraživana je pomoću deuterona energije 22 MeV do energije pobuđenja od 1.8 MeV pod kutovima od 20◦ , 30◦ i 50◦ . Najbolje energijsko razlučivanje iznosilo je 3.6 keV. Opažena je 91 energijska razina i određen je pripadni prijenos momenta impulsa

Gold fragmentation induced by stopped antiprotons

A natural gold target was irradiated with the antiproton beam from the Low Energy Antiproton Ring at CERN. Antiprotons of 200 MeV/c momentum were stopped in a thick target, products of their annihilations on Au nuclei were detected using the off-line gamma-ray spectroscopy method. In total, yields for 114 residual nuclei were determined, providing a data set to deduce the complete mass and charge distribution of all products with A > 20 from a fitting procedure. The contribution of evaporation and fission decay modes to the total reaction cross section as well as the mean mass loss were estimated. The fission probability for Au absorbing antiprotons at rest was determined to be equal to (3.8+-0.5)%, in good agreement with an estimation derived using other techniques. The mass-charge yield distribution was compared with the results obtained for proton and pion induced gold fragmentation. On the average, the energy released in pbar annihilation is similar to that introduced by ~ 1 GeV protons. However, compared to proton bombardment products, the yield distribution of antiproton absorption residues in the N-Z plane is clearly distinct. The data for antiprotons exhibit also a substantial influence of odd-even and shell effects.Comment: 14 pages, 9 figures, Revtex 4, to be published in Physical Review

Composition of the nuclear periphery from antiproton absorption

Thirteen targets with mass numbers from 58 to 238 were irradiated with the antiproton beam from the Low Energy Antiproton Ring facility at CERN leading to the formation of antiprotonic atoms of these heavy elements. The antiproton capture at the end of an atomic cascade results in the production of more or less excited residual nuclei. The targets were selected with the criterion that both reaction products with one nucleon less than the proton and neutron number of the target be radioactive. The yield of these radioactive products after stopped-antiproton annihilation was determined using gamma-ray spectroscopy techniques. This yield is related to the proton and neutron density in the target nucleus at a radial distance corresponding to the antiproton annihilation site. The experimental data clearly indicate the existence of a neutron-rich nuclear periphery, a "neutron halo", strongly correlated with the target neutron separation energy Bn and observed for targets with Bn < 10 MeV. For two-target nuclei 106Cd and 144Sm, with larger neutron binding energies, a proton-rich nuclear periphery was observed. Most of the experimental data are in reasonable agreement with calculations based on current antiproton-nucleus and pion-nucleus interaction potentials and on nuclear densities deduced with the help of the Hartree-Fock-Bogoliubov approach. This approach was, however, unable to account for the 106Cd and 144Sm results.Comment: Latex (RevTeX,aps style), 13 pages + 12 Postscript figure