Hard pion bremsstrahlung in the Coulomb region

Hard high-energy pion-nucleus bremsstrahlung, $\pi^- +A\to\pi^- +\gamma +A$, is studied in the Coulomb region, i.e. the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. Special attention is focussed on the possibility of measuring the pion polarizability in such reactions. We study the sensitivity to the structure of the underlying the pion-Compton amplitude through a model with $\sigma$, $\rho$, and a_1 exchanges. It is found that the effective energy in the virtual pion-Compton scattering is often so large that the threshold approximation does not apply.Comment: 18 pages, 5 figure

Wie es zur Wirtschafts-, Währungs- und Sozialunion kam : Wirtschaftliche Voraussetzungen und politische Vorbedingungen

Es gab, so verkünden seit nunmehr zwei Jahrzehnten die bundesdeutschen Medien, zum Zeitpunkt und zur Art und Weise, wie die Wirtschafts- und Währungsunion vollzogen wurde, keine Alternative. «Ich kenne keine ernsthafte Betrachtung, wie man es hätte anders machen können», äußerte sich der Chefunterhändler des Einigungsvertrages Wolfgang Schäuble in einem Interview im «Neuen Deutschland» im Mai 2009. Bezogen auf jene programmatischen Konzepte, die die Währungsunion im Transformationsprozess der DDR-Wirtschaft bzw. im Einigungsprozess anders platzieren wollten, stimmt Schäubles Aussage offensichtlich nicht. Doch siegte mit dem «Stichwortkonzept: Schritte zur deutschen Wirtschaftseinheit » das bessere Programm? Welche Motive hatten Kanzler Kohl bzw. Finanzminister Waigel die Währungsunion an den Beginn des wirtschaftpolitischen Transformationsprozesses in der DDR zu setzen? Glaubten beide wirklich, sich für das bessere, d. h. für die DDR-Bürger und für das Zusammenwachsen von DDR und BRD günstigere Konzept entschieden zu haben? Warum verweigerten sie sich so vehement jedem Vorschlag ausgewiesener Experten, die Transformation von der Planwirtschaft zur Marktwirtschaft in Ostdeutschland über mehrere Jahre statt über einige Monate zu vollziehen? Vermutlich ging es dem Bundeskanzler nur um eins – um den Machterhalt. Nur als «Kanzler der Einheit», hatte er alle Chancen im Herbst 1990 die anstehenden Bundestagswahlen zu gewinnen. So hat er das natürlich in seinen Memoiren nicht formuliert

Pion Compton scattering and bremsstrahlung

The pion-polarizability functions are structure functions of pion-Compton scattering. They can be assessed in high-energy pion-nucleus bremsstrahlung reactions, $\pi^- +A\to\pi^- +\gamma +A$. We present numerical expectations for pion-nucleus bremsstrahlung cross sections in the Coulomb region, i.e. the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. We investigate the prospects of measuring the polarizability functions for pion-Compton c.m. energies from threshold up to 1 GeV. A meson-exchange model is used for the pion-Compton amplitude.Comment: 20 pages, 11 figure

Coulomb-nuclear interference in pion-nucleus bremsstrahlung

Pion-nucleus bremsstrahlung offers a possibility of measuring the structure functions of pion-Compton scattering from a study of the small-momentum-transfer region where the bremsstrahlung reaction is dominated by the single-photon-exchange mechanism. The corresponding cross-section distribution is characterized by a sharp peak at small momentum transfers. But there is also a hadronic contribution which is smooth and constitutes an undesired background. In this communication the modification of the single-photon exchange amplitude by multiple-Coulomb scattering is investigated as well as the Coulomb-nuclear interference term.Comment: 21 pages, 5 figures. Eqs.(51,52) corrected; some new figure

After-action Analysis of the Magic Maggiore Workshop on Expert Support and Reachback

The European Commission’s Joint Research Centre (JRC) in collaboration with the Global Initiative to Combat Nuclear Terrorism (GICNT) organized a two and a half-day workshop on expert support and reachback entitled Magic Maggiore at the JRC Ispra, Italy in 28-30 March 2017. Through a series of presentations, case studies, panel discussions, and a demonstration exercise, Magic Maggiore helped raise awareness and build commitment towards technical reachback. Furthermore, the workshop presented best practices to address key challenges, and identified areas for future work in this field. The workshop included a real-time detection and reachback exercise of a hypothetical nuclear security incident, put on between the JRC (Ispra) and France (Paris). The demonstration focused on core components of alarm adjudication and information exchange between front line officers, a national reachback centre, and an advanced centralised reachback centre located in Paris. A list of concrete post-workshop activities has been generated. The purpose of the list is to pave the way for the identification of the next steps towards development of European capabilities for nuclear security and in more general, for CBRNE security. Reachback is necessary for alarm adjudication to provide timely information for a balanced response. Information sharing between competent authorities is of vital importance for nuclear security. Due to the variety of responsibilities, Technical, Scientific and Operational support needs to be defined. The Member States should consider developing joint protocols on data structures and data handling to ease the information flow and so the response time.JRC.E.2-Technology Innovation in Securit

Positron-neutrino correlations in 32Ar and 33Ar Decays: Probes of Scalar weak currents and nuclear isospin mixing

The positron-neutrino correlation in the 0^+ \to 0^+ \beta decay of ^{32}Ar was measured at ISOLDE by analyzing the effect of lepton recoil on the shape of the narrow proton group following the superallowed decay. Our result is consistent with the Standard Model prediction; for vanishing Fierz interference we find a=0.9989 \pm 0.0052 \pm 0.0036. Our result leads to improved constraints on scalar weak interactions. The positron-neutrino correlation in ^{33}Ar decay was measured in the same experiment; for vanishing Fierz interference we find a=0.944 \pm 0.002 \pm 0.003. The ^{32}Ar and ^{33}Ar correlations, in combination with precision measurements of the half-lives, superallowed branching ratios and beta endpoint energies, will determine the isospin impurities of the superallowed transitions. These will provide useful tests of isospin-violation corrections used in deducing |V_{\rm ud}| which currently indicates non-unitarity of the KM matrix.Comment: 15 pages, 6 figure

Reactions induced by 11Be beam at Rex-Isolde

The collision induced by the three Beryllium isotopes, 9,10,11Be, on a 64Zn target were investigated at Ec.m. ≈ 1.4 the Coulomb barrier. The experiments with the radioactive 10,11Be beams were performed at the Rex-Isolde facility at CERN. In the case of 9,10Be, elastic scattering angular distributions were measured whereas, in the 11Be case, the quasielastic scattering angular distribution was obtained. A strong damping of the quasielastic cross-section was observed in the 11Be case, in the angular range around the Coulomb-nuclear interference peak. In this latter case a large total-reaction cross-section is found. Such a cross-section is more than a factor of two larger than the ones extracted in the reactions induced by the non-halo Beryllium isotopes. A large contribution to the total-reaction cross-section in the 11Be case could be attributed to transfer and/or break-up event

Two-pion production in deuteron-deuteron collisions at low energies

The cross section for the dd -> 4He pi pi reaction is estimated near threshold in a two-step model where a pion created in a first interaction produces a second pion in a subsequent interaction. This approach, which describes well the rates of 2pi and eta production in the pd -> 3He pi pi and dd -> 4He eta reactions, leads to predictions that are much too low compared to experiment. Alternatives to this and the double-Delta model will have to be sought to explain these data.Comment: 5 pages with 4 postscript figure