abstract

In May 1911 Ernest Rutherford published a paper The Scattering of \(\alpha \)- and \(\beta \)-particles by Matter and the Structure of the Atom. Now it is usually considered to be the birth certificate of the atomic nucleus. Rutherford’s results are presented and discussed in a wider context of physics views of that time.

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With the discovery of the first radioactive chemical elements Maria Skłodowska-Curie made the step into the terra incognita of radioactive elements and isotopes. With the first quantitative measurement of nuclear radiation and the development of radiochemical separation she discovered polonium and radium. The alpha radiation was used for discoveries forming our picture of the atomic nucleus. She found that radiation originating from nuclear decay allows a look into the atomic nucleus. In this contribution, we will follow the discoveries, initiated by the work of Maria Skłodowska-Curie, on the way to present nuclear physics with modern rare-isotope facilities. Her legacy includes medical application of radiation, now being an integral part of modern nuclear medicine.

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Studying the weak nuclear response, especially the Gamow–Teller (GT) transitions starting from stable as well as unstable nuclei is one of the key issues in nuclear and nuclear-astrophysics. We studied the GT transitions by means of hadronic (\(^3{\rm He},\,t\)) charge-exchange reactions and complementary \(\beta \) decays. Owing to the simple \(\sigma \tau \) nature of the operator that causes GT transitions, information on the crucial and critical part of the nuclear structure can be studied. Under the assumption that isospin is a good quantum number, symmetry is expected for the structure of mirror nuclei and the GT transitions starting from them. The results from \(\beta \)-decay studies and the strength distribution of GT transitions from the (\(^3{\rm He},t\)) reaction are compared and also combined for the understanding of nuclear structure of far-from-stability nuclei.

abstract

The observation of atomic numbers \(Z\) that are 40% larger than that of Bi, the heaviest stable element, is an impressive extension of nuclear survival. Although the super heavy nuclei (SHN) are at the limits of Coulomb stability, shell stabilization lowers the ground-state energy, creates a fission barrier, and thereby enables the SHN to exist. The fundamentals of the modern theory concerning the mass limits of nuclear matter have been experimentally verified.

abstract

An overview of present experimental investigations of superheavy nuclei at SHIP is given. Using cold fusion reactions which are based on lead and bismuth targets, relatively neutron deficient isotopes of the elements from bohrium (\(Z=107\)) to copernicium (112) were synthesized at GSI in Darmstadt, Germany, and a neutron deficient isotope of element 113 at RIKEN in Wako, Japan. In hot fusion reactions of \(^{48}\)Ca projectiles with actinide targets more neutron rich isotopes of element 112 and new elements up to element 118 were produced at FLNR in Dubna, Russia. Recently, part of these data which represent the first identification of nuclei located on the predicted island of superheavy nuclei (SHN), was confirmed in independent experiments. The measured data combined with theoretical results were used for estimating cross-sections for production of element 120 isotopes. Also evaluated were the decay properties of these isotopes. An experiment for searching of isotopes of element 120 has been started at the GSI SHIP.

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The radioisotopes used for labeling the diagnostic and therapeutic radiopharmaceuticals are contemporaneously produced using neutrons in reactors and light charged particles from accelerators (cyclotrons). After the presentation of both methods the commercially available cyclotrons are reviewed. Some examples of the most popular medical radioisotopes are given. The new Radiopharmaceuticals Production and Research Centre at the University of Warsaw is presented.

abstract

The relation between the slope of the nuclear symmetry energy at saturation density and the neutron skin thickness is investigated. Constraints on the slope of the symmetry energy are deduced from the neutron skin data obtained in experiments with antiprotonic atoms. Two types of neutron skin are distinguished: the “surface” and the “bulk”. A combination of both types forms neutron skin in most of nuclei. A prescription to calculate neutron skin thickness and the slope of symmetry energy parameter \(L\) from the parity violating asymmetry measured in the PREX experiment is proposed.

abstract

LUNA (Laboratory for Underground Nuclear Astrophysics) is a nuclear astrophysics experiment running at the INFN Laboratori Nazionali del Gran Sasso (LNGS). Aim of the experiment is to measure the cross-section of fusion reactions that take place inside the stars and that, in the past, dominated the Big Bang nucleosynthesis (BBN). The low value of these cross-sections (varying from \(pb\) to \(fb\) and even smaller), in the astrophysical range of energies, prevent any kind of measurements at the Earth’s surface. On the other hand, the low background of the LNGS underground laboratory allows LUNA to investigate these reactions at energies of astrophysical interest without the necessity of an extrapolation from the highest energies. Recently, the LUNA Collaboration has been engaged in the study of the \(^2{\rm H}(\alpha ,\gamma ) ^6\)Li and \(^{17}{\rm O}(p,\gamma )^{18}\)F reactions. In this paper the experimental set-up will be described and the preliminary data will be discussed. The future possibilities of LUNA will also be outlined.

abstract

Presently two new research facilities are either already under construction (‘MEGa-Ray’ at Lawrence Livermore National Laboratory/US) or soon ready to start construction (ELI-Nuclear Physics in Bucharest/ Romania), both aiming to provide highly brilliant \(\gamma \) beams with so far unprecedented properties (ca. 10\(^{13}\) photons/s, energy resolution \(\leq \)10\(^{-3}\)) via Compton-backscattering of laser photons from a high-quality relativistic electron beam. With these intense, monochromatic \(\gamma \) beams, a new era of photonuclear physics will be enabled. It is envisaged to exploit the novel beams for highly-selective studies of extremely deformed nuclei in the multiple-humped potential energy landscape of the actinides via photofission. We will be able to populate gateway states in the first potential minimum of nuclei, predominantly originating from collective states in the (superdeformed) second or (hyperdeformed) third potential minimum, tunnelling back into the first well. The \(\gamma \) beam energy resolution of \(10^{-3}\) will allow to resolve individual resonances due to the lower level density in the higher potential minima. Excited states in these minima can be rather selectively populated with much larger intensities than achieved with former methods based on light-ion induced reactions. Also the large background from prompt fission with \(\sigma _{\rm isomer}/\sigma _{\rm prompt}\approx 10^{-5}\) is avoided. Hence a detailed \(\gamma \) spectroscopy in the second and third minimum will be enabled.

abstract

Experimental data sets of \(^{11}\)Be + \(^{120}\)Sn (\(E_{\rm lab} = 32\) MeV) quasielastic scattering and \(^{10}\)Be yield coming from the breakup of the projectile were analyzed by means of the continuum-discretized coupled-channel method. Comparison of the calculations and the experimental data suggests that the root-mean-square radius of the neutron wave function of the \(^{11}\)Be ground state is larger than that deduced previously from a high energy scattering experiment. The largest contribution to the breakup cross-section was found to come form Coulomb breakup, in good agreement with the observed post-acceleration of the detected \(^{10}\)Be. Large Coulomb-nuclear interference effects are found.

abstract

We have measured the angular distributions of elastic scattering and \(^{6,4}\)He fragments produced in the collisions of an exotic beam of \(^{8}\)He on a \(^{208}\)Pb target at laboratory energies of 18 and 22 MeV, just around the Coulomb barrier (19 MeV). The measurements were performed at the SPIRAL/GANIL facility in Caen, France. In this paper, we present preliminary data on elastic cross sections and discuss the results using optical model and coupled reaction channel calculations.

abstract

Delayed conversion-electron and \(\gamma \)-ray spectroscopy of \(A=151\) nuclei has been performed at the Lohengrin mass spectrometer of the ILL Grenoble. A previously reported 35.1-keV isomer of \(^{151}\)Pr has been determined to decay by an \(E1\) transition and its half-life of 50(8) \(\mu \)s measured for the first time. These data has been complemented by high-fold \(\gamma \)-ray coincidence data collected with the EUROGAM-II and GAMMASPHERE arrays of anti-Compton spectrometers to search for medium-spin excitations in these nuclei. The long half life of this isomer and the lack of intraband \(E1\) transitions show an absence of strong octupole correlations in the observed states of \(^{151}\)Pr.

abstract

We have investigated nuclear fragmentation reactions of a relativistic \(^{208}\)Pb beam. Ten isomeric states for nuclei with \(A=142\)–152 and \(Z=62\)–67 were observed. Measured isomeric ratios were compared, together with values from other experiments, with prediction of theoretical models. The discrepancies between the experimental and theoretical values were discussed in terms of transitions by-passing the isomer that are not included in the models.

abstract

In the framework of the two proton radioactivity studies, a Time Projection Chamber was recently developed at CENBG, in order to study the correlations between the two protons emitted. In fragmentation experiments performed at LISE3/GANIL, the \(2p\) radioactivity of \(^{45}\)Fe and \(^{54}\)Zn was directly observed with the TPC. Results on correlations between the two protons are presented and compared to a recent theoretical model.

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The decay of the extremely neutron deficient \(^{48}\)Ni was studied by means of an imaging time projection chamber which allowed recording tracks of charged particles. Four decays with two-proton tracks clearly corresponding to two-proton radioactivity were registered, providing the first direct evidence for this decay mode in \(^{48}\)Ni. The half-life of \(^{48}\)Ni is determined to be \(T_{1/2} = 2.1^{+1.4}_{-0.4}\) ms. The measured decay energy is 1.28(6) MeV.

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The decay of the \(I^{\pi }=K^{\pi }=8^{-}\) isomeric state in \(^{130}\)Ba was investigated using the \(^{122}\)Sn(\(^{12}\)C,4n)\(^{130}\)Ba reaction. The measurement was carried out in \(e\)–\(\gamma \) and \(\gamma \)–\(\gamma \) coincidence modes using an electron spectrometer coupled to the EAGLE gamma-ray array at the Heavy Ion Laboratory, University of Warsaw. Multipolarities and mixing ratios for the \(8^{-} \rightarrow 6^{+}\) and \(8^{-}\rightarrow 5^{+}\) transitions in \(^{130}\)Ba were derived from experimentally obtained internal conversion coefficients.

abstract

The decay rates of \(^7\)Be implanted into gold, platinum, graphite, kapton and Al\(_2\)O\(_3\) have been measured with an accuracy better than 0.1%. The results obtained are compared with the existing experimental data and confronted with theoretical predictions.

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Spectroscopy in the region of high masses is performed at the limits of the existing detection systems. Observation limits were recently pushed down to 11 nb with the prompt gamma-ray spectroscopy of \(^{246}\)Fm and \(^{256}\)Rf. The very high intensity beams that will be provided by the new SPIRAL2 LINAC accelerator, combined with the high transmission and selectivity power of the Super Separator Spectrometer S\(^3\), will provide an unprecedented access to nuclei with cross-sections in the nanobarn region. Using the latest technologies, the S\(^3\) Collaboration is designing a detection system based on recoil-decay tagging that will enable a major step in these physics cases.

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The fission probability of \(^{232}\)Pa was measured as a function of the excitation energy in order to search for hyperdeformed (HD) transmission resonances using the (d,pf) transfer reaction on a radioactive \(^{231}\)Pa target. The experiment was performed at the Tandem accelerator of the Maier–Leibnitz Laboratory (MLL) at Garching using the \(^{231}\)Pa (d,pf) reaction at a bombarding energy of \(E_d=12\) MeV and with an energy resolution of \(\Delta E=5.5\) keV. Two groups of transmission resonances have been observed at excitation energies of \(E^*=5.7\) and 5.9 MeV. The fine structure of the resonance group at \(E^*=5.7\) MeV could be interpreted as overlapping rotational bands with a rotational parameter characteristic to a HD nuclear shape (\(\hbar ^2/2{\mit \Theta }=2.05\) keV). The fission barrier parameters of \(^{232}\)Pa have been determined by fitting TALYS nuclear reaction code calculations to the overall structure of the fission probability.

abstract

We present a modified version of the Fusion by Diffusion model adapted to calculate cross sections and optimum bombarding energies for synthesis of superheavy nuclei in \(xn\) reactions. Model predictions of the cross sections for the synthesis of superheavy nuclei of the atomic numbers \(Z\) ranging from 104 to 113 in \(1n\), \(2n\) and \(3n\) reactions with the use of lead and bismuth targets are compared with the experimental data from GSI Darmstadt, LBNL Berkeley and RIKEN Tokyo.

abstract

To identify the atomic number of superheavy nuclei produced in \(^{48}\)Ca-induced fusion-evaporation reactions, an experiment aiming at measuring characteristic X-rays is being prepared at GSI, Darmstadt, Germany. The gas-filled separator TASCA will be employed, sending the residues towards the multi-coincidence detector setup TASISpec. Two ion-optical modes relying on differing magnetic polarities of the quadrupole magnets can be used at TASCA. New simulations and experimental tests of transmission and background suppression for these two focusing modes into TASISpec are presented.

abstract

The impact of different magnetic field configurations on efficiency of internal conversion electron spectrometer was studied. The CST Particle Studio code allows to simulate electron trajectories in a highly inhomogeneous magnetic field produced by set of permanent magnets. It is shown that the suitable selection of permanent magnets can significantly improve electron transmission.

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The data acquisition (DAQ) system of the HPGe-detector array HORUS at the Institute for Nuclear Physics at the University of Cologne is currently being updated. Instead of using analogue DAQ techniques to obtain \(\gamma \) and particle spectra as well as the corresponding coincidence matrices, the 80 MHz Multichannel Digital Gamma Finder (DGF-4C Rev. F) developed by XIA, which samples the pre-amplifier signal directly, is employed. The DGF module and the new DAQ have been tested extensively and compared to the former analogue data acquisition using \(\alpha \) and \(\gamma \) sources and the results of these tests are presented.

abstract

The \(^{134}\)Nd required for studies of the violation of the \(K\) selection rule for electromagnetic transitions in nuclei with mass numbers around 130 can be produced in the reaction of \(^{122}\)Te with \(^{16}\)O. The \(^{122}\)Te target was prepared by the evaporation in a high vacuum. The deposition of the Te isotope on the backing was performed from the very close distance to economize the usage of the isotopic material. The thickness distribution of the target material determined by measurements of the alpha particles energy loss was estimated as 32%. The first test of the target on the \(^{16}\)O beam with energy of 80 MeV and intensity of 40 enA proved that target prepared by the Te deposition on the Au backing in vacuum is stable in the in-beam conditions and in spite of its relatively high inhomogeneity is suitable for the planned studies.

abstract

Dipole transitions in the semi-magic nucleus \(^{124}\)Sn have been investigated by means of real photon scattering in order to complete a previous measurement. The experiment was performed at the superconducting Darmstadt electron linear accelerator S-DALINAC using an unpolarized, continuous spectrum of bremsstrahlung with an endpoint energy of approximately 7.8 MeV. A concentration of dipole transitions in the energy range between 5 and 7 MeV stemming from the pygmy dipole resonance (PDR) could be identified. Some of these states have been observed in an (\(\alpha ,\alpha ' \gamma \)) experiment for the first time and could now be confirmed in our measurement.

abstract

Preliminary results of an analysis of experiments devoted to a study of the sensitivity of the \(^{20}\)Ne + \(^{208}\)Pb quasi-elastic angular distributions at two near-barrier energies and the previously measured corresponding barrier distribution to the value of the nuclear quadrupole deformation length of \(^{20}\)Ne are reported.

abstract

The aim of this study was to determine the activity concentrations of \(^{234,238}\)U isotopes in mineral, medicinal and spring waters in spas situated in the Sudety and the Outer Carpathian Mountains and to compare the uranium content found in waters from these regions. Samples were collected over a period of 7 years (2005–2011) from 86 water intakes from the Sudety Mountains and Fore-Sudetic block and from 37 water intakes from Outer Carpathians. On the basis of the calculated activity concentrations of \(^{234,238}\)U as well as the existing data on \(^{226,228}\)Ra, the annual effective doses resulting from the consumption of these isotopes were evaluated.

abstract

Seven years ago, the GSI Online Mass Separator was decommissioned after 30 years of operation. The Golden Age of Jan Żylicz, celebrated at this Conference, is an adequate occasion to review the research performed at this facility. Its programme reached from nuclear-structure studies based on decay spectroscopy — the focus of this contribution — to investigations of nuclear shapes by means of laser spectroscopy all the way to experiments of astrophysical and fundamental-physics relevance. Reviewing this work I shall present my personal view on, firstly, examples of technical and scientific highlights and, secondly, the “humanistic” aspect of collaborating with many colleagues from abroad, including in particular Jan Żylicz and his associates from the University of Warsaw.