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In recent experiments, the new concept of calorimetric low-temperature detectors (CLTDs) was applied for the first time for the investigation of isotopic yields of fission fragments. Fragments from neutron-induced fission sources were mass-separated by the LOHENGRIN spectrometer at the ILL Grenoble and, after passing silicon nitride membranes used as degraders, detected in a CLTD array. The new detector concept of a thermal detector provides a fundamental advantage over conventional ionization-mediated detectors, in particular for heavier particle masses at low energies. Using fissile targets of235U,239Pu and241Pu, nuclear-charge separation was studied in the mass region 82 ≤ A ≤ 139. For light fragments, the Z resolution matches historically best values with conventional techniques, while for heavier masses substantial improvement was attained. We have gained first LOHENGRIN data on the isotopic yields in the light-mass group of241Pu. Towards mass-symmetry, known Z-yield data were supplemented in the range A = 110 to 113 for241Pu and239Pu. Extended data sets were cumulated for A = 92 and 96 due to a recent request from studies on the reactor anti-neutrino spectrum. Furthermore, considerable progress was achieved to extend isotopic yield measurements up to the heavy-mass region, hardly accessible until now.

R. Reifarth et al: ; 12 págs.; 9 figs.; Open Access funded by Creative Commons Atribution Licence 3.0 ; Nuclear Physics in Astrophysics VI (NPA6), The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process ow and r-process -decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will oer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes., This project was supported by the HGF Young Investigators Project VH-NG-327, EMMI, H4F, HGS-HIRe, JINA, NAVI, DFG and ATHENA.

The Glauber model analysis of the elastic $^{6,8}\mathrm{He}+p$ scattering data at energies around 700 MeV/nucleon, measured in two separate experiments at GSI-Darmstadt, has been carried out using several phenomenological parametrizations of the nuclear matter density. By taking into account the new data points measured at high-momentum transfer, the nuclear matter radii of $^{6,8}\text{He}$ have been accurately determined from the Glauber model analysis of the data, with the spin-orbital interaction explicitly taken into account. The well-known geometry for the core and dineutron halo has been used with the new parametrizations of the $^{6}\text{He}$ density to extract the detailed information on the structure of $^{6}\text{He}$ in terms of the core and dineutron halo radii. An enhanced sensitivity of the data measured at high-momentum transfer to the core part of the $^{6,8}\text{He}$ densities has been found.

High-energy interaction cross sections of A = 20 nuclei (20N, 20O, 20F, 20Ne, 20Na, 20Mg) on carbon were measured with accuracies of ≈ 1%. The nuclear matter r.m.s. radii derived from the measured cross sections show an irregular dependence on isospin projection. The largest difference in radii, which amounts to approximately 0.2 fm, has been obtained for the mirror nuclei 20O and 20Mg. The influence of nuclear deformation and binding energy on the radii is discussed. By evaluating the difference in r.m.s. radii of neutron and proton distributions, evidence has been found for the existence of a proton skin for 20Mg and of a neutron skin for 20N.

Low temperature calorimetric detectors may become a powerful tool for atomic and nuclear physics experiments. Such detectors are operated by reading out the temperature rise of an absorber after thermalization of the kinetic energy which is deposited by an incident particle or photon. Due to the Debye law highest sensitivity is obtained at low operating temperatures. The operating principle and the expected properties of calorimetric low temperature detectors are discussed. Such detectors promise a substantial advantage over conventional detection schemes with respect to basic detector properties, as for example energy resolution, detection threshold, resistance against radiation damage, etc.

As a first step of the EXL project scheduled for the New Experimental Storage Ring at FAIR a precursor experiment (E105) was performed at the ESR at GSI. For this experiment, an innovative differential pumping concept, originally proposed for the EXL recoil detector ESPA, was successfully applied. The implementation and essential features of this novel technical concept will be discussed, as well as details on the detectors and the infrastructure around the internal gas-jet target. With Ni-56(p, p)Ni-56 elastic scattering at 400 MeV u(-1), a nuclear reaction experiment with stored radioactive beams was realized for the first time. Finally, perspectives for a next-generation EXL-type setup are briefly discussed.

The tensor analyzing power of the reaction 1 H ( d , γ) 3 He has been measured at θcm = 96° and deuteron energies of 29.2 and 45.3 MeV. It arises from the interference of the transitions to the 3He S- and D-states and allows a selective check of the D-state wave function. The experimental result is compared to a Faddeev calculation treating both continuum and bound states exactly.

Ground-state and transition densities for 5 osmium and platinum isotopes A = 188 − 196 have been measured by electron scattering (qmax = 3.2 fm−1), and compared to dynamical Hartree-Fock-Bogoliubov calculations performed with a finite-range density- dependent force. Among the various microscopic calculations performed, only the full HFB calculation which allows for the triaxial, γ-soft nature of these nuclei, correctly reproduces the data.

The lifetime of the 2S state in (μ−4He)+ ions has been measured at He-gas pressures between 50 Torr and 6 atm (T=300 K). We observed both X-rays from the two-photon 2S→1S transitions as well as delayed Kα X-rays associated with radiative quenching. The quenching rate is strongly pressure dependent; it is predominantly a quadratic function of pressure with a measured three-body rate coefficient k=(5.9±0.8)×10−32 cm6/s. At 6 atm, we find τ2S

Angular distributions of the cross section and of the vector analyzing power for the 58Ni(7 Li , 6Li)59Ni reaction leading to several groups of levels in the final nucleus have been measured at ELi = 20.3 MeV. The observed Q-value dependence of the vector analyzing power can to a large extent be attributed to a kinematical effect caused by the polarization of the orbital angular momentum of the transferred neutron in 7Li.

Using the vector polarized 6Li-beam of the Heidelberg EN-Tandem1) the elastic scattering of 6Li on 12C, 16O, 28Si and 58Ni has been investigated at a bombarding energy of ELi = 22.8 MeV. The structure of the observed angular distributions of σ/σR depends in heavy ion scattering critically on E/Ecoul. Therefore the observed angular distributions of σ/σR display for 12C (E/Ecoul≈ 3.5) an oscillating pattern (fig.1) which looks like Frauenhofer diffraction scattering. The angular distribution of σ/σR for 58Ni (E/Ecoul≈ 1.4) is without any structure (fig.1) and looks like Fresnel diffraction scattering. The analyzing power had been obtained by measuring successively with a polarized and unpolarized beam (high frequency transition of the source1) on and off respectively). The polarization of the beam is known to be between 0.52 and 0.6. The lower bound is deduced from the highest up to now with this source observed asymmetry in the 6Li-4He elastic scattering2). The higher bound is estimated from the source parameters itself1). The polarization was monitored after some couple of runs either with the 1H(6Li,4He)3He reaction or, in a later stage of the experiment using the elastic scattering of 6Li on 12C. Around θcm = 44.5° and ELi = 22.8 MeV a flat maximum of the asymmetry connected with a fairly high cross section had been observed (fig.1).

With a vector polarized 6 Li beam the 12 C( 6 Li, d) and 12 C( 6 Li,α) reactions have been investigated at E Li =20.0 MeV. The observed analyzing powers turn out to be large. The four-nucleon transfer to the ground state of 16 O is well described by an optical potential (central and spin-orbit) which was obtained from the elastic scattering of vector polarized 6 Li on 12 C.

The elastic scattering of aligned 6 Li and 7 Li on 58 Ni at E cm = 12.7 MeV displays an “isotopic” effect which can be traced to the very different (mass) quadrupole moments of both isotopes. The elastic scattering of aligned 6 Li and 7 Li on 12,13 C at E Li = 9 MeV displays large effects, but the angular dependence is much more complicated compared to the scattering on 58 Ni.

The scattering of aligned 7 Li on 58 Ni at E Li = 14.22 MeV was investigated for different spin alignment axes of the mass quadrupole moment of 7 Li. For a fixed scattering angle the change in cross section due to the alignment of the quadrupole moment turns out to be proportional to the change in distance between the 7 Li and 58 Ni surfaces at the distance of closest approach.

A mass spectrometer has been set up at the on‐line isotope separator ISOLDE at CERN/Geneva. Mass‐separated radioactive ions are stored in a Penning trap. Their mass is determined by a measurement of the cyclotron frequency in the magnetic field of a superconducting magnet. A resolving power of up to 300.000 and a precision of some 10 keV were determined in case of mass measurements of neutron‐deficient RB and Cs isotopes. The resonance of the isobars 88Sr and 88Rb were clearly resolved and evidence was obtained for an isomer in 122Cs.

A bunched beam of alkali ions with a pulse length of about 10 μs and an energy of 1 KeV has been retarded electrostatically and captured in flight into a Penning trap. A trapping efficiency of up to 70% has been determined. Subsequently the cyclotron resonance was induced. In the case of K a line width of the resonance of 4 Hz was measured at a resonance frequency of 2.3 MHz. This enables mass determinations of unstable nuclei produced at on-line mass separators with an accuracy in the sub-ppm region.

4 pages, 3 tables, 2 figures.-- PACS nrs.: 21.10.Ft, 21.10.Ky, 27.70.+q., On-line resonance-ionization mass spectrometry has been applied to determine the isotope shift and hyperfine structure of 185-189Au and 189mAu in the 6s 2S(1/2)→6p 2p 1/2 (λ=268 nm) transition. The Au atoms were obtained as daughters of mass-separated Hg isotopes produced at the ISOLDE facility at CERN ionized by a three-color, two-step resonant photoionization process, detected and mass-selected by time of flight. A drastic change of the nuclear charge radius was observed between 187Au and 186Au, which is interpreted as an onset of strong deformation of β≈0.25 in 186Au and 185Au., This work has been funded by the German Federal Minister for Research and Technology (Bundesminister für Forschung und Technologie) under Contract No. MZ-458-1. One of us {J.L.W.) was supported in part by U.S. Department of Energy Contract No. DE-AS05-80ER10599.

29 pages, 5 tables, 12 figures.-- This publication comprises part of the thesis of K. Wallmeroth., The hyperfine structure and isotope shifts of short-lived gold isotopes with 185 ≤ A ≤190 and the l1-/2 isomer of 189Au have been investigated by application of on-line resonance ionization mass spectroscopy. A detection efficiency of ε = 10-8 for gold atoms was observed at a background of about one event per 1000 laser shots. The deduced charge radii show a drastic change between A=187 and A=186 which is interpreted as an onset of strong deformation (β2 ≈ =0.25) in 186Au and 185Au due to the influence of the πlh(9/2) intruder orbital., This work has been funded by the German Federal Minister for Research and Technology (Bundesministerium für Forschung und Technologie) under contract No. Mz-458-I, by the US Dept. of Energy grant No. De-FG05-87ER40330 (Ga.Tech.) and by NATO research grant No. RG-86/0452 (INP, Gent and Ga. Tech).

4 pages, 1 table, 4 figures., On-line resonance ionization mass spectrometry has been applied to determine the isotope shift and hyperfine structure of 185–189Au and tne I=11/2 isomer of 189Au in the 6s 2S(1/2)-->6p2P(1/2) (h = 268 nm) transition. The Au atoms were obtained as daughters of mass-separated Hg isotopes produced at the ISOLDE facility at CERN, ionized by a three-step resonant photoionization process, detected and mass-selected by time of flight. A drastic change of the nuclear charge radius was observed between 187Au and 186Au, which is interpreted as an onset of strong deformation of β2 ≈ 0.25 in 186Au and 185Au., This work has been supported by the Bundesministerium für Forschung und Technologie. One of us, J. Wood was supported in part by the U.S. Department of Energy, Contract DE-AS05-80 ER 10599.

2014 An atomic beam source for negative polarized lithium ions is operated at the Heidelberg EN-Tandem since 1974. A highly efficient surface ionizer is used. Vector and tensor polarized beams of 6Li (I = 1) and 7Li (I = 3/2) have been produced with currents up to 150 nA of Li3+ at the target. The second rank tensor polarization of both beams is calibrated absolutely. Preliminary results of producing a polarized 23Na beam are reported. REVUE DE PHYSIQUE APPLIQUEE TOME 12, OCTOBRE 1977, PAGE Sources for negative polarized light ions (p and d) are frequently used at Tandem accelerators as a tool in nuclear physics [1, 2]. Attempts to produce negative polarized beams of heavier particles have resulted in the Los Alamos source for tritium ions [3] and the Heidelberg source for alkali ions [4, 5] which FIG. 1. Source for negative polarized alkali ions. (*) On leave from the Instytut Badan Jadrowych, Warsaw. is subject of the present paper. An interesting aspect of polarized alkali beams is the large nuclear deformation of 7Li and 23Na which seems to be of great interest in heavy ion physics [6]. 1. Polarized atomic beam. The ion source shown in figure 1 makes use of the atomic beam FIG. 2. Hfs splitting in an external magnetic field for J = 1/2, 1= 3/2 (7Li, 23Na). The critical fields Be are given in table 1. Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/rphysap:0197700120100156700

International audience

International audience; The N=28 shell closure is the first arising from the strong spin-orbit interaction. Therefore, the study of its evolution in nuclei with large neutron to proton excesses is intimately connected to the evolution of the spin-orbit interaction. From the doubly magic 48Ca nucleus to the close to drip line 42Si nucleus, a wealth of nuclear structure modifications is occurring, starting from spherical, prolate-spherical co-existence to oblate shapes. Using up to date experimental data along the N=28 isotonic chain, the underlying physics origin for these structural modifications will be emphasized. Among these, the action of tensor forces and the central density dependence of the spin-orbit interaction will be invoked.