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The heaviest elements can exclusively be produced in actinide-target based nuclear fusion reactions with intense heavy-ion beams. Ever more powerful accelerators deliver beams of continuously increasing intensity, which brings targets of current technology to their limits and beyond. We motivate efforts to produce targets with improved properties, which calls for a better understanding of targets produced by molecular plating, the current standard method. Complementary analytical methods will help shedding more light on their chemical and physical changes in the beam. Special emphasis is devoted to the aspect of the optimum target thickness and the choice of the backing material. [ABSTRACT FROM AUTHOR]

A novel combination of advanced gas-chromatography and detection systems coupled to a buffer-gas cell was characterized on-line to allow gas-phase chemical studies of accelerator-produced short-lived α -decaying mercury, francium, and astatine isotopes. These were produced in 40Ar- and 48Ca-induced nuclear fusion–evaporation reactions, subsequently isolated in the recoil separators MARS at Texas A&M University, USA, and TASCA at GSI Darmstadt, Germany, before being thermalized in a buffer-gas-stopping cell. From the latter, the nuclear reaction products were extracted into gas-phase chromatographic systems, suitable for registering α -decaying short-lived radionuclides, such as isotopes of superheavy elements. Efficiencies of 21(3)% for 204-209Fr were reached for the extraction into the optimized miniCOMPACT gas-chromatography setup, indicating that this technique enables the identification of isotopes of volatile as well as non-volatile elements. These studies guide the path towards chemical investigations of superheavy elements beyond flerovium, which are out of reach with currently used setups. [ABSTRACT FROM AUTHOR]

For heavy-ion beam experiments, self-supporting carbon thin films are needed as targets, stripper foils and as backings (Nucl. Instr. and Meth. A 334 (1993) 69) for materials which cannot be produced self-supporting.Using resistance evaporation under high vacuum, self-supporting carbon foils with a thickness of 5 μg/cm2 and a diameter of 10 mm, a thickness of 10 μg/cm2 and a diameter of 50 mm up to a thickness of 50 μg/cm2 and a diameter of 300 mm can be obtained. Due to the energy impact of the heavy-ion beam, the amorphous carbon is restructured into textured graphite, as was found already by Dollinger et al. (Nucl. Instr. and Meth. A 303 (1991) 79). The authors discuss the production process as well as the change of the layer structure caused by the energy deposit. [Copyright &y& Elsevier]

We have measured for the first time simultaneously both the mean charge states and stopping powers of (35–280) MeV/u 208Pb ions in gases and solids with an accuracy of 1%. The existence at lower energies and disappearance at higher of density effects in the charge-state distribution and the corresponding stopping power are directly confirmed and comparisons with widely used theories and simulations for heavy ions demonstrate strong deviations of up to 27%. However, an unprecedented prediction power of better than 3% has been achieved for the energy loss when the measured mean charge-states are implemented in the Lindhard-Sørensen theory. Our present benchmark data contribute to an improved understanding of the basic atomic collision processes and to numerous applications in nuclear physics. Extending the GANIL data [1] to higher accuracy and energies, we can now answer at which velocities the Bohr-Lindhard density effect in stopping will vanish. [ABSTRACT FROM AUTHOR]

In this work, we present results from the investigations of high-Kisomers in 255Rf, 256Rf and 257Rf isotopes produced in 50Ti+ 207Pb and 50Ti+208Pb reactions. The method of time and position correlation searchwas used to identify ER–CE–α/SF events in the data. Previously knownhigh-Kstates in 256Rf and 257Rf were confirmed. A search for high-Kisomer in 255Rf was performed for the first time. Observation of ER–CEcorrelations with a lifetime of≈30μs indicates the presence of isomericstates also in this isotope. [ABSTRACT FROM AUTHOR]

Presents information on a study that examined Bi[sub1.7]Pb[sub0.3]Sr[sub2]Ca[sub2]Cu[sub3]O[subx] by means of differential scanning calorimetry, thermogravimetry and room and high temperatures x-ray diffraction in different atmospheres. Methodology of the study; Results of the study.

Measured binary quasifission mass spectra in reactions with actinide nuclides show a large peak in yield near the doubly-magic 208Pb. This has generally been attributed to the enhanced binding energy of 208Pb causing a valley in the potential energy surface, attracting quasifission trajectories. To investigate this interpretation, binary quasifission mass spectra and cross-sections have been measured at near-barrier energies for reactions of 50Ti with actinide nuclides from 238U to 249Cf. Cross-sections have also been deduced for sequential fission (a projectile-like nucleus and two fragments from fission of the complementary target-like nucleus). Binary cross-sections fall from ∼70% of calculated capture cross-sections for 238U to only ∼40% for 249Cf, with a compensating increase in sequential fission cross-sections. The data are consistent with the 208Pb peak originating largely from sequential fission of heavier fragments produced in more mass-asymmetric primary quasifission events. These are increasingly suppressed as the heavy quasifission fragment mass increases above 208Pb. The important role of sequential fission calls for re-interpretation of quasifission characteristics and dynamics in superheavy element synthesis reactions. [ABSTRACT FROM AUTHOR]

Two short-lived isotopes 221U and 222U were produced as evaporation residues in the fusion reaction 50Ti + 176Yb at the gas-filled recoil separator TASCA. An a decay with an energy of Eα = 9.31(5) MeV and half-life T1/2 = 4.7(7) μs was attributed to 222U. The new isotope 221U was identified in α-decay chains starting with Eα = 9.71(5) MeV and T1/2 = 0.66(14) μs leading to known daughters. Synthesis and detection of these unstable heavy nuclei and their descendants were achieved thanks to a fast data readout system. The evolution of the N = 126 shell closure and its influence on the stability of uranium isotopes are discussed within the framework of a-decay reduced width. [ABSTRACT FROM AUTHOR]

We investigated the formation of nuclear molecules and the occurrence of time delays in reactions of the superheavy systems Ni + Pb ( $ Z_{1}+Z_{2}=110$), Xe + Pb ( $ Z_{1}+Z_{2}=136$) and U + U ( $ Z_{1}+Z_{2}=184$. In deep inelastic binary reactions of Ni + Pb and Xe + Pb we observed clear signatures for the formation of long-living molecule-like nuclear systems which rotate by large angles of 180 degree. The evolution of the nuclear molecules was accompanied by large energy dissipation and a strong deformation of the nuclear system. The results from the giant system U + U revealed striking similarities to the ones from Ni + Pb and Xe + Pb , showing that significant time delays still occur in the heaviest accessible systems. The experiments were performed at the velocity filter SHIP at GSI and at the VAMOS spectrometer at GANIL. [ABSTRACT FROM AUTHOR]

Mass distributions of fission fragments from the compound nuclei 180 Hg and 190 Hg formed in fusion reactions 36 Ar + 144 Sm and 36 Ar + 154 Sm, respectively, were measured at initial excitation energies of E ⁎ ( Hg 180 ) = 33 – 66 MeV and E ⁎ ( Hg 190 ) = 48 – 71 MeV . In the fission of 180 Hg, the mass spectra were well reproduced by assuming only an asymmetric-mass division, with most probable light and heavy fragment masses A ¯ L / A ¯ H = 79 / 101 . The mass asymmetry for 180 Hg agrees well with that obtained in the low-energy β + / EC -delayed fission of 180 Tl, from our earlier ISOLDE(CERN) experiment. Fission of 190 Hg is found to proceed in a similar way, delivering the mass asymmetry of A ¯ L / A ¯ H = 83 / 107 , throughout the measured excitation energy range. The persistence as a function of excitation energy of the mass-asymmetric fission for both proton-rich Hg isotopes gives strong evidence for the survival of microscopic effects up to effective excitation energies of compound nuclei as high as 40 MeV. This behavior is different from fission of actinide nuclei and heavier mercury isotope 198 Hg. [ABSTRACT FROM AUTHOR]

In deep inelastic multinucleon transfer reactions of 48 Ca + 248 Cm we observed about 100 residual nuclei with proton numbers between Z = 82 and Z = 100 . Among them, there are five new neutron-deficient isotopes: 216 U, 219 Np, 223 Am, 229 Am and 233 Bk. As separator for the transfer products we used the velocity filter SHIP of GSI while the isotope identification was performed via the α decay chains of the nuclei. These first results reveal that multinucleon transfer reactions together with here applied fast and sensitive separation and detection techniques are promising for the synthesis of new isotopes in the region of heaviest nuclei. [ABSTRACT FROM AUTHOR]

Levels in 223Th populated by the a decay of 227U were investigated using α-γ decay spectroscopy. The 227U isotope was produced in the fusion-evaporation reaction Ne22+Pb208 at the velocity filter separator for heavy-ion reaction products at Gesellschaft für Schwerionenforschung in Darmstadt (Germany). Several new excited levels and γ transitions were identified in 223Th. An improved α-decay scheme of 227U was suggested. The experimental α-decay energy spectrum of 227U was compared with the Monte Carlo simulation performed using the toolkit geant4. [ABSTRACT FROM AUTHOR]

Background: Mass-asymmetric fission has been observed in low energy fission of 180Hg. Calculations predicted the persistence of asymmetric fission in this region even at excitation energies of 30-40 MeV. Purpose: To investigate fission mass distributions by populating different isotopes of Hg using heavy ion fusion reactions. Methods: Fission fragment mass-angle distributions have been measured for two reactions, 40Ca + 142Nd and 13C + 182W, populating 182Hg and 195Hg, respectively, using the Heavy Ion Accelerator Facility and CUBE spectrometer at the Australian National University. Measurements were made at beam energies around the capture barrier for the two reactions and mass ratio distributions were obtained using the kinematic reconstruction method. Results: Asymmetric fission has been observed following the population of 182Hg at an excitation energy of 22.8 MeV above the saddle point. A symmetric peaked mass ratio distribution was observed for 195Hg nuclei at a similar excitation energy above the saddle point. Conclusions: Mass-asymmetric fission has been observed in neutron deficient Hg nuclei populated via heavy ion fusion for the first time. The results are consistent with observations from beta-delayed fission measurements and provide a proof-of-principle for expanding experimental studies of the influence of shell effects on the fission processes. [ABSTRACT FROM AUTHOR]

The isotope 176Au has been studied in the complete fusion reaction 40Ca + 141Pr → 176Au + 5n at the velocity filter SHIP (GSI, Darmstadt). The complex fine-structure α decay of two isomeric states in 176Au feeding several previously unknown excited states in the daughter nucleus 172Ir is presented. An α-decay branching ratio of bα = 9.5(11)% was deduced for the high-spin isomer in 172Ir. [ABSTRACT FROM AUTHOR]

Superheavy elements are produced via fusion reactions, by bombarding thin target foils with intense beams of energetic ions with energies around the Coulomb barrier. Currently, production of targets of rare isotopes relies mainly on the molecular plating (MP) method, which yields thin films of the desired target material on a backing foil. Intense heavy-ion beams are known to modify the film structure, which leads to deterioration of the targets over irradiation time. To gain a better understanding of the processes at a microscopic scale, comparative tests were carried out using Coulomb barrier heavy-ion beams provided from the UNILAC accelerator at GSI Darmstadt, Germany. For this purpose, targets of lead were prepared using MP and Drop-on-Demand inkjet-printing. Lead targets were baked-in and analysed by digital optical microscopy, scanning electron microscopy and confocal Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Decay properties of the neutron-deficient nuclides 201-203Ra and 200-202Fr were investigated using α- and γ-decay spectroscopy. The nuclei were produced in fusion-evaporation reactions of 56Fe projectiles with enriched 147Sm and 149Sm targets at the velocity filter SHIP at GSI in Darmstadt (Germany). The α decay from the (3/2-) state in 201Ra was identified with an energy Eα = 7842(12) keV and half-life T1/2 = 8-4+40 ms. Ambiguous decay properties for 202Ra from previous measurements were clarified by remeasuring with significantly improved precision, resulting in values of Eα = 7722(7) keV and T1/2 = 3.8-0.8+1.3 ms. New short-lived isomeric states were identified in 200Fr and 201Fr with half-lives of 0.6-0.2+0.5 μs and 0.7-0.2+0.5 μs, respectively. A tentative spin and parity of 13/2+ were assigned to the latter. One event attributed to β-delayed fission of 200Fr was observed. [ABSTRACT FROM AUTHOR]

The heaviest elements are synthesized in heavy-ion induced hot fusion reactions with various actinide targets. Because the actinide material is often available only in very limited amounts, a deposition method with high yields (~90 %) is needed. We report on the production of Pu, Am, Cm, Bk, and Cf targets on thin Ti backings by molecular plating. Different chemical purification steps using ion chromatographic techniques were applied for the purification of Cf and Pu. The deposition procedure applied for the production of ~0.4-0.8 mg/cm thick targets is described. The deposition yield was determined either by α-particle or γ-ray spectroscopy. Furthermore, neutron activation analysis has been applied in the case of Pu, Am, and Cm. Information about the spatial distribution and homogeneity of the target layer was obtained by radiographic imaging. [ABSTRACT FROM AUTHOR]

We report on the development of new materials for laser-ion acceleration applicable for the advanced mechanism of radiation-pressure-acceleration. These targets are ultra-thin with thicknesses of just a few nm. For several years, diamond-like carbon foils in this thickness range can be produced. An alternative material containing more than one ion-species has the potential to further improve the acceleration mechanism. The fabrication and characterization of self-supporting polymer-based targets will be described in this paper. Furthermore, we show the significant influence on a radiation-pressure induced acceleration process by experimental data. [ABSTRACT FROM AUTHOR]

We investigated multi-nucleon transfer reactions in collisions of 58Ni + 207Pb and 64Ni + 207Pb at Coulomb barrier energies. The new aspect is that we used a velocity filter (SHIP at GSI) for the separation of the heavy target-like transfer products from background events. The isotopic identification was performed via the $ \alpha$ decay properties of the reaction products. The goal of the experiment was to study the characteristics of multi-nucleon transfer reactions in the region of heavy nuclei and the applicability of existing separation and detection techniques, which are usually used for identification of heavy fusion-evaporation residues, to heavy transfer products. This was motivated by recent theoretical results from macroscopic-microscopic models which suggest deep inelastic transfer reactions in heavy systems as a means to produce new neutron-rich isotopes in the region of N = 126 and in the region of superheavy nuclei. In this paper we present the isotopic yields, the excitation functions and the excitation energies of the heavy transfer products with Z > 82 as well as the influence of shell effects on the reaction products. The influence of the different neutron numbers of the projectiles is also discussed. [ABSTRACT FROM AUTHOR]

In recent experiments at the velocity filter Separator for Heavy Ion reaction Products (SHIP) (GSI, Darmstadt), an extended and improved set of α-decay data for more than 20 of the most neutron-deficient isotopes in the region from lead to thorium was obtained. The combined analysis of this newly available α-decay data, of which the 186Po decay is reported here, allowed us for the first time to clearly show that crossing the Z = 82 shell to higher proton numbers strongly accelerates the α decay. From the experimental data, the α-particle formation probabilities are deduced following the Universal Decay Law approach. The formation probabilities are discussed in the framework of the pairing force acting among the protons and the neutrons forming the α particle. A striking resemblance between the phenomenological pairing gap deduced from experimental binding energies and the formation probabilities is noted. These findings support the conjecture that both the N = 126 and Z = 82 shell closures strongly influence the α-formation probability. [ABSTRACT FROM AUTHOR]

Detailed α-decay studies of 179TIg and its daughter products 175Aug and 17lIrg were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). First unambiguous determination of the α-decay properties of 175Aug was performed as follows: Ea = 6433(4) keV, T1/2 = 207(7) ms, and α-decay branching ratio 90(7)%. First determination of the α-decay branching ratios for 179TIg and 171Irg was also made:ba(179TIg) = 60(2)% and ba(171Irg) = 15(2)%. The spins of the ground states in 175Au and 171Ir are established as l/2+. [ABSTRACT FROM AUTHOR]

Decay properties of the very neutron-deficient isotopes 197-199Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the 2n-4n evaporation channels of the fusion-evaporation reaction 60Ni + 141Pr &#rarr; 201Fr*. Improved α-decay properties of 199Fr were determined and the possible existence of two α-decaying states in this nucleus is discussed. For the isotope 198Fr a broad α-decay energy distribution was detected in the range of (7470-7930) keV and two α-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope l97Fr was identified based on the observation of one α-decay chain yielding Eα = 7728(15) keV and 71/2 = 0.6-0.3+0.3 ms. The systematics of reduced α-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes. [ABSTRACT FROM AUTHOR]

In this contribution, we report on results of recent experiments performed at the velocity filter SHIP at GSI in Darmstadt obtained for nuclei above fermium (Z = 100). In particular, new results are presented from an α-decay study of 259Sg. These data resulted in the observation of new isomeric state in 259Sg and in the improvement of the quasiparticle systematics for N = 153 isotones. [ABSTRACT FROM AUTHOR]

By using the recoil-fission correlation technique, the exotic process of beta-delayed fission (βDF) was unambiguously identified in the very neutron-deficient nuclei 192,194At in experiments at the velocity filter SHIP at Gesellschaft für Schwerionenforschung (GSI). The upper limits for the total kinetic energy release in fission of 192,194Po, being the daughter products of 192-194At after β+/EC decay, were estimated. The possibility of an unusually high βDF probability for 192 At is discussed. [ABSTRACT FROM AUTHOR]

By using the technique of correlating implanted evaporation residues and their subsequent fission decay, β-delayed fission βDF) of 186Bi has been identified for the first time and βDF of 188Bi has been unambiguously confirmed. The experiments were performed at the velocity filter SHIP (GSI, Darmstadt). The βDF probabilities for both nuclides were qualitatively estimated, and, in particular indications for a large value in the case of 186Bi are regarded. [ABSTRACT FROM AUTHOR]

Abstract: The average charge states of 188Pb and 252,254No ions in dilute helium gas were measured at the gas-filled recoil separator TASCA. Hydrogen gas was also used as a filling gas for measurements of the average charge state of 254No. Helium and hydrogen gases at pressures from 0.2mbar to 2.0mbar were used. A strong dependence of the average charge state on the pressure of the filling gases was observed for both, helium and hydrogen. The influence of this dependence, classically attributed to the so-called “density effect”, on the performance of TASCA was investigated. The average charge states of 254No ions were also measured in mixtures of helium and hydrogen gases at low gas pressures around 1.0mbar. From the experimental results simple expressions for the prediction of average charge states of heavy ions moving in rarefied helium gas, hydrogen gas, and in their mixture were derived. [Copyright &y& Elsevier]

The synthesis of element 116 in fusion-evaporation reactions of a Ca beam with radioactive Cm targets was studied at the velocity filter SHIP of GSI in Darmstadt. At excitation energies of the compound nuclei of 40.9MeV, four decay chains were measured, which were assigned to the isotope 116, and one chain, which was assigned to 116. Measured cross-sections of (3.4) pb and (0.9), respectively, and decay data of the chains agree with data measured previously at the Flerov Laboratory of Nuclear Reactions in Dubna. As a new result, one α-decay chain was measured, which terminates after four α decays by spontaneous fission. The α energies of the second-to-fourth decay are considerably higher than those measured for the α decays of 114, Cn, and Ds and the spontaneous fission half-life is significantly longer than that of Hs measured in previous experiments. A possible assignment is discussed in the frame of excited quasiparticle states of nuclei populated in the decay chain from 116. Also other possible assignments were considered and are discussed. At an excitation energy of 45.0MeV no events were observed resulting in a one-event cross-section limit of 1.6 pb. The technical aspects related with the use of radioactive target material at SHIP are described in detail. The experience gained in this experiment will serve as a basis for future experiments aiming to study still heavier elements at the velocity filter SHIP. [ABSTRACT FROM AUTHOR]

The one-neutron removal cross sections of neutron-rich Al isotopes and longitudinal momentum distributions of the residues have been measured for A = 33 to 36 at relativistic energies (≈900 MeV/u). The inclusive data have been interpreted within the eikonal approximation. The evolution of the single-particle occupancy in the ground state of 33,34,35A1 has been studied and compared with shell model predictions. The inferred 2s1/2 neutron occupancy in the 33A1 ground-state wave function is 20% to 40% lower than the predicted one. The inclusive data do not exclude the presence of intruder states. Some intruder / = 1 occupancy is found in 34A1, similarly to 33Mg. The single-particle 1 f7/2 occupancy shows a gradual increase at N = 22. Correspondingly, a decrease of the lrf3/2 strength has been observed. [ABSTRACT FROM AUTHOR]

New measurements of the interaction cross sections of 22,230 at 900A MeV performed at the GSI, Darmstadt are reported that address the unsolved puzzle of the large cross section previously observed for 230. The matter radii for these oxygen isotopes extracted through a Glauber model analysis are in good agreement with the new predictions of the ab initio coupled-cluster theory reported here. They are consistent with a 220 + neutron description of 230 as well. [ABSTRACT FROM AUTHOR]

Abstract: TRAKULA (Transmutationsrelevante kernphysikalische Untersuchungen langlebiger Aktinide, i.e., nuclear physical investigations of long-lived actinides with relevance to transmutation) is a joint research project of the German Federal Ministry of Science and Education (BMBF) on nuclear physics investigations with modern scientific, technological and numerical methods. Experiments concerning the transmutation of radioactive waste are a central topic of the project. For this, large-area samples (≥40cm2) of 235,238U and 239,242Pu compounds are required for the calibration of fission chambers and for fission yield measurements. Another topic within the project requires large-area targets for precise measurements of the half-life, t 1/2, of very long-lived α-particle emitters like 144Nd (t 1/2≈2×1015 y). Here, we report on electrodeposition tests with Gd and Nd (used as chemical homologs of the actinides), which were performed to find optimal deposition conditions for small-area targets that should be applicable to future large-area targets. The layers were produced by molecular plating. A new stirring technique, ultrasonic stirring, was adopted and found to be suitable for producing large-area targets. Moreover, two different current densities (namely 0.7 and 1.4mA/cm2) were studied and found appropriate for target preparation. Characterization of the layers with different analytical techniques played a major role in these studies to gain a deeper understanding of the deposition process itself: neutron activation analysis and γ-spectroscopy were used for yield measurements, radiographic imaging for homogeneity studies, scanning electron microscopy for morphology studies, and atomic force microscopy for roughness studies. According to the obtained results, a new electrochemical cell for the production of large-area targets was designed. [Copyright &y& Elsevier]

The production of residual nuclei in the reactions 25Mg + 206Pb, 36S + natPt, 48Ca + natW was investigated at low bombarding energies at the velocity filter SHIP (GSI, Darmstadt). The data are discussed within the dinuclear System model. In particular, the emission of complex fragments with Z > 2 from heavy compound nuclei is treated within the model and supported by the experimental data. The production Channels and cross sections, Charge, isotopic distributions of the residual heavy nuclei are presented. [ABSTRACT FROM AUTHOR]

The interaction cross sections of 32-35Mg at 900A MeV have been measurmed using the fragment separator at GSI. The deviation from the r0A1/3 trend is slightly larger for 35Mg, signaling the possible formation of a longer tail in the neutron distribution for 35Mg. The radii extracted from a Glauber model analysis with Fermi densities are consistent with models predicting the development of neutron skins. [ABSTRACT FROM AUTHOR]

The new neutron-deficient isotope Th was produced in the complete-fusion reaction Ni + Sm $ \rightarrow$Th + 3n . Evaporation residues were separated in-flight by the velocity filter SHIP and subsequently identified on the basis of energy-, position- and time-correlated $ \alpha$ -decay chains. The measured $ \alpha$ -decay energy and half-life value of Th are 8044(30)keV and 1.7 ms, respectively. Improved data on the $ \alpha$ -decay of Th , Th , Th and Ra were obtained using complete-fusion reactions of Ni with Sm , Sm , and Sm targets. [ABSTRACT FROM AUTHOR]

The isotopes Cf were produced in irradiations of Pb targets with S ions. At bombarding energies close to the Coulomb barrier two or three neutrons were evaporated from the compound nuclei Cf . Cross-sections were on the order of a few hundred nanobarns. For the isotope Cf a spontaneous fission branching of 0.015±0.002 was determined. The new isotope Cm was produced by $ \alpha$ decay of Cf and identified by $ \alpha$ - $ \alpha$ correlations. It decays with an $ \alpha$ -decay energy of (6954± 20)keV and a half-life of (410±50 s. For the first time, the $ \alpha$ decay of Cf was observed having an energy of (8081±20 keV. For the isotope Cm a half-life of ( 23 s was measured for first time. Spontaneous fission of Cf was confirmed and mass-excess values of the nuclei Cm and Cf were determined. [ABSTRACT FROM AUTHOR]

The isotope Sg and its decay product Rf were produced in the nuclear reaction Pb(Cr, n)Sg . The radioactive decay of these isotopes was investigated by means of $ \alpha$ , $ \alpha$ - $ \gamma$ and/or $ \alpha$ -X-ray spectroscopy. Improved spectroscopic data concerning $ \alpha$ energies, $ \gamma$ transitions, tentative spin and parity assignments of low-lying Nilsson single-neutron orbitals are presented for these nuclei. [ABSTRACT FROM AUTHOR]

Abstract: The first reaction spectroscopy on the ground state structure of 33Mg through the measurement of the longitudinal momentum distribution from the one-neutron removal reaction using a C target at is reported. The experiment was performed at the FRS, GSI. The distribution has a relatively narrow width ( (FWHM)) and the one-neutron removal cross-section is . An increased contribution from the orbital is required to explain the observation showing its lowering compared to existing model predictions. This provides new information regarding the configuration of 33Mg and the island of inversion. [Copyright &y& Elsevier]

We investigated the capture stage and successive nucleon transfer from the projectile to the target in the superheavy system 64 28Ni + 207 82Pb ( Zproj. + Ztarget = 110) . The target-like transfer products were detected at forward angles of (0±2) degrees, such, we selected nuclei resulting from central collisions. The data reveal several analogies to cold fusion reactions leading to superheavy elements. The observations are in accordance with the two-center shell model. The experiments have been performed at the velocity filter SHIP at GSI. [ABSTRACT FROM AUTHOR]

The isotope 261Bh was produced in the reaction 209Bi(54Cr, 2n)261Bh and its $ \alpha$ decay has been remeasured. It was found that it populates by an unhindered transition of $ \approx$ 10 MeV an excited level at E * > 350 keV in the daughter nucleus 257Db . The latter decays by internal transitions either into the isomeric state or the ground state. A somewhat improved half-life value of T1/2 = 11.8+3.9 -2.4 ms was obtained for 261Bh . The data support the previous assignment of the $ \alpha$ activities 257Db (1) and 257Db (2) to the isomer and to the ground state, respectively. No evidence for an isomeric state in 261Bh decaying by $ \alpha$ emission was found. Based on the experimental results and theoretical calculations a partial decay scheme of 261Bh including spin and parity assignments of the ground-state and excited levels in the daughter nucleus 257Db populated by the $ \alpha$ decay and succeeding internal transitions have been suggested. 261Bh represents so far the heaviest nucleus for which such an attempt has been made. No spontaneous fission (SF) events that could be attributed to 261Bh were observed, resulting in an SF branching bSF < 0.05 . The measured production cross-section is (64±15) pb at E * = 22 MeV. [ABSTRACT FROM AUTHOR]