Evidence for energy dependent interaction in one-particle transfer reactions between heavy ions

Abstract The recently measured proton stripping cross sections in the collision 16 O+ 208 Pb at 793 MeV [M.C. Mermaz et al., Z. Phys. A 326 (1987) 353] is analyzed in the semiclassical approximation. Taking into account an energy dependence in the interaction, consistent with the proton scattering data, an accurate description of the absolute cross sections is obtained

Effect of angular-momentum dissipation and fluctuation on energy coherence lengths and time evolution in the dissipative collision 28Si + 48Ti

Abstract We analyze the energy autocorrelation functions and the energy coherence lengths in the strongly dissipative collision 28 Si (E lab = 130 MeV ) + 48 Ti for Z = 11 and 12 reaction fragments. It is found that in order to obtain a good fit of both the energy-averaged angular distributions and the angular dependence of the energy coherence lengths one has to take into account (i) the dissipation and fluctuation of the relative angular momentum of the dinucleus and (ii) the contribution from direct (fast) reactions in addition to the statistical (relative slow) interaction processes. The established angular dependence is a direct consequence of the angular-momentum dissipation-fluctuation effects on the time-space evolution of the intermediate dinucleus

Mass Measurements near N=Z

Abstract After an outline of the physics motivations, that illustrate why we think it is important to measure masses in the region N≈Z, we report on on experiments performed at Ganil. An experiment aimed at measuring the masses of proton-rich nuclei in the mass region A ≈ 60–80 has been performed, using a direct time-of-flight technique in conjunction with SISSI and the SPEG spectrometer at GANIL. The nuclei were produced via the fragmentation of a 78 Kr beam (73 meV/nucleon). A novel technique for the purification of the secondary beams, based on the stripping of the ions and using the α and the SPEG spectrometers, was succesfully checked. It allows for good selectivity without altering the beam quality. Secondary ions of 100 Ag, 100 Cd, 100 In and 100 Sn were produced via the fusion-evaporation reaction 50 Cr + 58 Ni at an energy of 5.1 MeV/nucleon, and were accelerated simultaneously in the second cyclotron of GANIL (CSS2). About 10 counts were observed from the production and acceleration of 100 Sn 22+ . The masses of 100 Cd, 100 In and 100 Sn were measured with respect to 100 Ag using the CSS2 cyclotron, with precisions of 2 × 10 −6 , 3 × 10 −6 and 10 −5 respectively

Depth of maximum of air-shower profiles at the Pierre Auger Observatory : II. Composition implications

Using the data taken at the Pierre Auger Observatory between December 2004 and December 2012, we have examined the implications of the distributions of depths of atmospheric shower maximum (Xmax), using a hybrid technique, for composition and hadronic interaction models. We do this by fitting the distributions with predictions from a variety of hadronic interaction models for variations in the composition of the primary cosmic rays and examining the quality of the fit. Regardless of what interaction model is assumed, we find that our data are not well described by a mix of protons and iron nuclei over most of the energy range. Acceptable fits can be obtained when intermediate masses are included, and when this is done consistent results for the proton and iron-nuclei contributions can be found using the available models. We observe a strong energy dependence of the resulting proton fractions, and find no support from any of the models for a significant contribution from iron nuclei. However, we also observe a significant disagreement between the models with respect to the relative contributions of the intermediate components.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Exacta

Depth of maximum of air-shower profiles at the Pierre Auger Observatory : II. Composition implications

Using the data taken at the Pierre Auger Observatory between December 2004 and December 2012, we have examined the implications of the distributions of depths of atmospheric shower maximum (Xmax), using a hybrid technique, for composition and hadronic interaction models. We do this by fitting the distributions with predictions from a variety of hadronic interaction models for variations in the composition of the primary cosmic rays and examining the quality of the fit. Regardless of what interaction model is assumed, we find that our data are not well described by a mix of protons and iron nuclei over most of the energy range. Acceptable fits can be obtained when intermediate masses are included, and when this is done consistent results for the proton and iron-nuclei contributions can be found using the available models. We observe a strong energy dependence of the resulting proton fractions, and find no support from any of the models for a significant contribution from iron nuclei. However, we also observe a significant disagreement between the models with respect to the relative contributions of the intermediate components.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Exacta

Calculation of a complete set of spin observables for proton elastic scattering from stable and unstable nuclei

A microscopic study of proton elastic scattering from unstable nuclei at intermediate energies using a relativistic formalism is presented. We have employed both the original relativistic impulse approximation (IA1) and the generalised impulse approximation (IA2) formalisms to calculate the relativistic optical potentials, with target densities derived from relativistic mean field (RMF) theory using the NL3 and FSUGold parameter sets. Comparisons between the optical potentials computed using both IA1 and IA2 formalisms, and the different RMF Lagrangians are presented for both stable and unstable targets. The comparisons are required to study the effect of using IA1 versus IA2 optical potentials, with different RMF parameter sets, on elastic scattering observables for unstable targets at intermediate energies. We also study the effect of full-folding versus the factorized form of the optical potentials on elastic scattering observables. As with the case for stable nuclei, we found that the use of the full-folding optical potential improves the scattering observables (especially spin observables) at low intermediate energy (e.g. 200MeV). No discernible difference is found at a projectile incident energy of 500 MeV. To check the validity of using localized optical potential, we calculate the scattering observables using non-local potentials by solving the momentum space Dirac equation. The Dirac equation is transformed to two coupled Lippmann-Schwinger equations, which are then numerically solved to obtain elastic scattering observables. The results are discussed and compared to calculations involving local coordinate-space optical potentials

Spectral Calibration of the Fluorescence Telescopes of the Pierre Auger Observatory

We present a novel method to measure precisely the relative spectral response of the fluorescence telescopes of the Pierre Auger Observatory. We used a portable light source based on a xenon flasher and a monochromator to measure the relative spectral efficiencies of eight telescopes in steps of 5 nm from 280 nm to 440 nm. Each point in a scan had approximately 2 nm FWHM out of the monochromator. Different sets of telescopes in the observatory have different optical components, and the eight telescopes measured represent two each of the four combinations of components represented in the observatory. We made an end-to-end measurement of the response from different combinations of optical components, and the monochromator setup allowed for more precise and complete measurements than our previous multi-wavelength calibrations. We find an overall uncertainty in the calibration of the spectral response of most of the telescopes of 1.5% for all wavelengths; the six oldest telescopes have larger overall uncertainties of about 2.2%. We also report changes in physics measurables due to the change in calibration, which are generally small.Peer Reviewe

Syklinen eurooppalaistuminen, koronakriisi ja Suomi

Artikkeli tarkastelee asiantuntijahaastatteluihin perustuen, miten erilaiset mutta toisiinsa limittyneet toiminnalliset logiikat ohjasivat EU:n ja sen jäsenvaltioiden, erityisesti Suomen, politiikkaa pandemian ensimmäisen runsaan puolentoista vuoden aikana. Logiikkoja hahmottuu kolme – itsekkyys, matkiminen ja koordinaatio – mutta ne muodostavat yhdessä kokonaisuuden, jota voidaan kuvata syklisen eurooppalaisuuden käsitteellä. Vaikka eurooppalaistumisen normatiivinen perusajatus ei kriisissä näytä horjuneen, koronatoimet toivat näkyväksi jännitteen toimivallaltaan rajoitetun ja eurooppalaisia ratkaisuja etsivän komission sekä itsekkäästi käyttäytyvien jäsenmaiden välillä. Samalla jäsenmaat ovat yhteisessä tilanteessa ja yksiselitteisen tieteellisen tiedon puuttuessa matkineet toisiaan sekä oppineet toisiltaan. Vaikka ongelmia oli, artikkeli osoittaa, että EU:n kyky yhdistää joustavasti erilaisia toimintatapoja ja -logiikoita muodostivat eurooppalaisuutta eteenpäin vievän voiman. Tämä konkretisoi puhetta siitä, kuinka EU kehittyy kriisien kautta.This article examines, based on expert interviews, how different but overlapping logics of action guided the policies of the EU and its member states, especially those of Finland, in the first year and a half of the pandemic. We see three inherent logics – selfishness, emulation and coordination – taking shape, together assembling a form of what we call cyclical Europeanisation. Even though the normative principle of Europeanisation does not seem to have faltered, actions regarding the pandemic make apparent the tension between the Commission and the selfish member states. At the same time, the member states have found themselves in the situation together and have emulated each other’s policy measures under conditions of ambiguous scientific information. Regardless of the problems incurred, the ability to revert the tensions between the logics and also combine them pragmatically have formed a driving force for Europeanisation that further bolsters the argument of how the EU develops through crises – and not simply in terms of one-dimensional emergency governance

Depth of maximum of air-shower profiles at the Pierre Auger Observatory : II. Composition implications

Using the data taken at the Pierre Auger Observatory between December 2004 and December 2012, we have examined the implications of the distributions of depths of atmospheric shower maximum (Xmax), using a hybrid technique, for composition and hadronic interaction models. We do this by fitting the distributions with predictions from a variety of hadronic interaction models for variations in the composition of the primary cosmic rays and examining the quality of the fit. Regardless of what interaction model is assumed, we find that our data are not well described by a mix of protons and iron nuclei over most of the energy range. Acceptable fits can be obtained when intermediate masses are included, and when this is done consistent results for the proton and iron-nuclei contributions can be found using the available models. We observe a strong energy dependence of the resulting proton fractions, and find no support from any of the models for a significant contribution from iron nuclei. However, we also observe a significant disagreement between the models with respect to the relative contributions of the intermediate components.La lista completa de autores que integran el documento puede consultarse en el archivo.Facultad de Ciencias Exacta