A search for production of the superheavy elements with atomic numbers 119 and 120 was performed in the Ti-50 + Bk-249 and Ti-50 + Cf-249 fusion-evaporation reactions, respectively, at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. Over four months of irradiation, the Bk-249 target partially decayed into Cf-249, which allowed for a simultaneous search for both elements. Neither was detected at cross-section sensitivity levels of 65 and 200 fb for the Ti-50 + Bk-249 and Ti-50 + Cf-249 reactions, respectively, at a midtarget beam energy of E-lab = 281.5 MeV. The nonobservation of elements 119 and 120 is discussed within the concept of fusion-evaporation reactions including various theoretical predictions on the fission-barrier heights of superheavy nuclei in the region of the island of stability.

The neutron-deficient isotopes 254,255Rf were produced in the fusion-evaporation reaction 50Ti+206Pb at the gas-filled recoil separator TASCA. Decay properties of these nuclei were investigated by applying fast digital electronics. A search for isomeric states in both isotopes was performed by using the accompanying conversion electron emissions. Isomeric states with half-lives of 4(1) μs and >30 μs were measured for 254Rf and 255Rf, respectively, which confirm the findings at different separators. The present experimental results demonstrate the great potential of fast digital electronics for measurements of isomeric states in the heaviest nuclei, which are only producible in small quantities.

J. Khuyagbaatar,1,2,* A. Yakushev,2 Ch. E. Düllmann,1,2,3 D. Ackermann,2,† L.-L. Andersson,1 M. Asai,4 M. Block,2 R. A. Boll,5 H. Brand,2 D. M. Cox,6,‡ M. Dasgupta,7 X. Derkx,1,3 A. Di Nitto,3 K. Eberhardt,1,3 J. Even,1,§ M. Evers,7 C. Fahlander,8 U. Forsberg,8 J. M. Gates,9 N. Gharibyan,10 P. Golubev,8 K. E. Gregorich,9 J. H. Hamilton,11 W. Hartmann,2 R.-D. Herzberg,6 F. P. Heßberger,1,2 D. J. Hinde,7 J. Hoffmann,2 R. Hollinger,2 A. Hübner,2 E. Jäger,2 B. Kindler,2 J. V. Kratz,3 J. Krier,2 N. Kurz,2 M. Laatiaoui,2 S. Lahiri,12 R. Lang,2 B. Lommel,2 M. Maiti,12,‖ K. Miernik,5 S. Minami,2 A. Mistry,6,¶ C. Mokry,1,3 H. Nitsche,9,** J. P. Omtvedt,13 G. K. Pang,9 P. Papadakis,6,14 D. Renisch,3 J. Roberto,5 D. Rudolph,8 J. Runke,2 K. P. Rykaczewski,5 L. G. Sarmiento,8 M. Schädel,2,4 B. Schausten,2 A. Semchenkov,13 D. A. Shaughnessy,10 P. Steinegger,15,16 J. Steiner,2 E. E. Tereshatov,10,†† P. Thörle-Pospiech,1,3 K. Tinschert,2 T. Torres De Heidenreich,2 N. Trautmann,3 A. Türler,15,16 J. Uusitalo,14 D. E. Ward,8 M. Wegrzecki,17 N. Wiehl,1,3 S. M. Van Cleve,5 and V. Yakusheva1 1Helmholtz Institute Mainz, 55099 Mainz, Germany 2GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany 3Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany 4Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan 5Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA 6University of Liverpool, Liverpool L69 7ZE, United Kingdom 7The Australian National University, Canberra, ACT 0200, Australia 8Lund University, 22100 Lund, Sweden 9Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 10Lawrence Livermore National Laboratory, Livermore, California 94551, USA 11Vanderbilt University, Nashville, Tennessee 37235, USA 12Saha Institute of Nuclear Physics, Kolkata 700064, India 13University of Oslo, 0315 Oslo, Norway 14University of Jyväskylä, 40351 Jyväskylä, Finland 15Paul Scherrer Institute, 5232 Villigen, Switzerland 16University of Bern, 3012 Bern, Switzerland 17The Institute of Electron Technology, 02-668 Warsaw, Poland

Multipolarity measurements are presented for transitions in the deformed odd-mass nucleus 167 Yb in support of tentative spin assignments and level interpretations based upon the cranked-Nilsson model. Internal-conversion coefficients were measured with the SAGE (Silicon And GErmanium) spectrometer confirming several E2 transition assignments. The array of high-purity germanium detectors enabled the recording of high-multiplicity events from which $\gamma\gamma\gamma$ and $\gamma\gamma e^{-}$ data sets were extracted and the technique of high-fold $\gamma$-ray gating was demonstrated to cleanly isolate transitions of interest.

Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch E.; Ackermann, D.; Andersson, L. L.; Asai, M.; Block, M.; Boll, R. A.; Brand, H.; Cox, D. M.; Dasgupta, M.; Derkx, X.; Di Nitto, A.; Eberhardt, K.; Even, J.; Evers, M.; Fahlander, C.; Forsberg, U.; Gates, J. M.; Gharibyan, N.; Golubev, P.; Gregorich, K. E.; Hamilton, J. H.; Hartmann, W.; Herzberg, R. D.; Heßberger, F. P.; Hinde, D. J.; Hoffmann, J.; Hollinger, R.; Hübner, A.; Jäger, E.; Kindler, B.; Kratz, J. V.; Krier, J.; Kurz, N.; Laatiaoui, M.; Lahiri, S.; Lang, R.; Lommel, B.; Maiti, M.; Miernik, K.; Minami, S.; Mistry, A.; Mokry, C.; Nitsche, H.; Omtvedt, J. P.; Pang, G. K.; Papadakis, P.; Renisch, D.; Roberto, J.

The heaviest currently known nuclei, which have up to 118 protons, have been produced in Ca-48 induced reactions with actinide targets. Among them, the element tennessine (Ts), which has 117 protons, has been synthesized by fusing Ca-48 with the radioactive target Bk-249, which has a half-life of 327 d. The experiment was performed at the gas-filled recoil separator TASCA. Two long and two short a decay chains were observed. The long chains were attributed to the decay of Ts-294. The possible origin of the short-decay chains is discussed in comparison with the known experimental data. They are found to fit with the decay chain patterns attributed to Ts-293. The present experimental results confirm the previous findings at the Dubna Gas-Filled Recoil Separator on the decay chains originating from the nuclei assigned to Ts.

The isotopic distribution of nuclei produced in the 50Ti + 249Cf reaction has been studied at the gas-filled recoil separator TASCA at GSI Darmstadt, which separates ions according to differences in magnetic rigidity. The bombardment was performed at an energy around the Bass barrier and with the TASCA magnetic fields set for collecting fusion-evaporation reaction products. Fifty-three isotopes located “north-east” of 208Pb were identified as recoiling products formed in non-fusion channels of the reaction. These recoils were implanted with energies in two distinct ranges; besides one with higher energy, a significant low-energy contribution was identified. The latter observation was not expected to occur according to kinematics of the known types of reactions, namely quasi-elastic, multi-nucleon transfer, deep-inelastic collisions or quasifission. The present observations are discussed within the framework of two-body kinematics passing through the formation of a composite system.

The isotopic distribution of nuclei produced in the 50 Ti + 249 Cf reaction has been studied at the gas- filled recoil separator TASCA at GSI Darmstadt, which separates ions according to differences in magnetic rigidity. The bombardment was performed at an energy around the Bass barrier and with the TASCA magnetic fields set for collecting fusion-evaporation reaction products. Fifty-three isotopes located “north-east” of 208 Pb were identified as recoiling products formed in non-fusion channels of the reaction. These recoils were implanted with energies in two distinct ranges; besides one with higher energy, a significant low-energy contribution was identified. The latter observation was not expected to occur according to kinematics collisions or quasifission. The present observations are discussed within the framework of two-body kinematics passing through the formation of a composite system.

Short-lived α-decaying nuclei "northeast" of 208 Pb in the chart of nuclides were studied using the reaction 48 Ca + 243 Am with the decay station TASISpec at TASCA, GSI Darmstadt.Decay energies and times from pile-up events were extracted with a tailor-made pulse-shape analysis routine and specific α-decay chains were identified in a correlation analysis.Decay chains starting with the even-even 220 Ra and its odd-A neighbors, 219 Fr, and 221,219 Ra, with a focus on the 219 Ra → 215 Rn decay, were studied by means of α-γ spectroscopy.A revised α-decay scheme of 219 Ra is proposed, including a new decay branch from a previously not considered isomeric state at 17 keV excitation energy.Conclusions on nuclear structure are drawn from the experimental data, aided by Geant4 simulations and a discussion on theoretical calculations.

Eggs of sterlet are discharged outside into ambient aquatic environment where egg activation and fertilization occur. Effects of different activation media including freshwater and clay suspension on protein abundances of egg were quantified in sterlet Acipenser ruthenus. In-gel digestion and high resolution mass spectrometry were used for label-free protein quantification in the eggs of five females. No significant (p > 0.05) difference was found between protein abundances in eggs activated with different media. However, results showed significant (p < 0.05, fold change ≥2) reduction in the abundances of nine proteins including six glycoproteins, enolase and heat shock protein in activated groups compared to freshly ovulated eggs as control. The fact that abundance of proteasome subunit alpha significantly reduced only in eggs which were activated by clay suspension suggests that activation medium can somehow intervene with protein regulation during fertilization. In conclusion, external fertilization in sturgeon egg is accompanied by huge release of proteins into the external environment that may participate in the construction of a transient microenvironment around egg for attraction and protection of spermatozoa to ensure ensuing fertilization. Data are available via ProteomeXchange with identifier PXD006232.

An experimental scheme combining the mass resolving power of a Penning trap with contemporary decay spectroscopy has been established at GSI Darmstadt. The Universal Linear Accelerator (UNILAC) at GSI Darmstadt provided a Ca-48 beam impinging on a thin Er-170 target foil. Subsequent to velocity filtering of reaction products in the Separator for Heavy Ion reaction Products (SHIP), the nuclear ground state of the 5n evaporation channel Ra-213 was mass-selected in SHIPTRAP, and the Ra-213 ions were finally transferred into an array of silicon strip detectors surrounded by large composite germanium detectors. Based on comprehensive GEANT4 simulations and supported by theoretical calculations, the spectroscopic results call for a revision of the decay path of Ra-213, thereby exemplifying the potential of a combination of a mass-selective Penning trap device with a dedicated nuclear decay station and contemporary GEANT4 simulations.

Products of the fusion-evaporation reaction Ca-48 + Am-243 were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum fur Schwerionenforschung, Darmstadt, Germany. Amongst the detected thirty correlated alpha-decay chains associated With the production of element Z = 115, two recoil-alpha-fission and five recoil-alpha-alpha-fission events were observed. The latter five chains are similar to four such events reported from experiments performed at the Dubna gas-filled separator, and three such events reported from an experiment at the Berkeley gas-filled separator. The four chains observed at the Dubna gas-filled separator were assigned to start from the 2n-evaporation channel (289)115 due to the fact that these recoil-alpha-alpha-fission events were observed only at low excitation energies. Contrary to this interpretation, we suggest that some of these recoil-alpha-alpha-fission decay chains, as well as some of the recoil-alpha-alpha-fission and recoil-alpha-fission decay chains reported from Berkeley and in this article, start from the 3n-evaporation channel (288)115. (C) 2016 Elsevier B.V. All rights reserved.

After mating, spermatophores of signal crayfish are stored on the body of the female for a period before fertilization. This study compared the post-mating protein profile and pattern of protein tyrosine phosphorylation of the signal crayfish spermatophore to that of the freshly ejaculated spermatophore and found substantial differences. Two major bands of tyrosine-phosphorylated proteins of molecular weights 10 and 50kDa were observed in the freshly ejaculated spermatophore of the signal crayfish. While the tyrosine-phosphorylated protein band with molecular weight 10kDa was formed by protein(s) of similar pH, the band with molecular weight of 50kDa consisted of proteins of varying pH. In the post-mating spermatophore, the band with molecular weight of 50kDa was not detected, and an increase in the level of protein tyrosine phosphorylation was observed in the 10kDa band. The microtubular radial arms of the spermatozoon showed a positive reaction to an anti-tyrosine antibody conjugated with gold particles in both the freshly ejaculated and post-mating spermatophores. In conclusion, the male gamete of the signal crayfish undergoes molecular modification during post-mating storage on the body of the female including changes in the level of protein expression and protein tyrosine phosphorylation. Structural similarity of the radial arms in the crayfish immotile spermatozoon with flagellum, which is the main site of protein tyrosine phosphorylation in the mammalian motile spermatozoa, raises questions regarding evolution and function of such organelles across the animal kingdom that must be addressed in the future studies.

The fission process still remains a main factor that determines the stability of the atomic nucleus of heaviest elements. Fission half-lives vary over a wide range, 10−19−1024 s. Present experimental techniques for the synthesis of the superheavy elements that usually measure α-decay chains are sensitive only in a limited range of half-lives, often 10−5−103 s. In the past years, measurement techniques for very short-lived and very long-lived nuclei were significantly improved at the gas-filled recoil separator TASCA at GSI Darmstadt. Recently, several experimental studies of fission-related phenomena have successfully been performed. In this paper, results on 254−256Rf and 266Lr are presented and corresponding factors for retarding the fission process are discussed.

Rudolph, Dirk; Forsberg, Ulrika; Düllmann, C. E.; Golubev, Pavel; Heßberger, F.P.; Khuyagbaatar, J.; Kratz, J. V.; Sarmiento, Luis; Yakushev, A.; Ackermann, D.; Andersson, L.; Block, M.; Brand, H.; Cox, D.; Derkx, X.; Di Nitto, A.; Eberhardt, K.; Even, J.; Fahlander, Claes; Gates, J. M.; Gerl, J.; Gregorich, E. K.; Gross, C. J.; Herzberg, R.-D.; Jäger, E.; Kindler, B.; Krier, J.; Kojouharov, I.; Kurz, N.; Lommel, B.; Mistry, A.; Mokry, C.; Nitsche, H.; Omtvedt, J. P.; Papadakis, P.; Runke, J.; Rykaczewski, K.; Schädel, M.; Schaffner, H.; Schausten, B.; Thörle-Pospiech, P.; Torres, T.; Traut, T.; Trautmann, N.; Türler, A.; Ward, A.; Wiehl, N. Published in: GSI Report

Thirty correlated α-decay chains were observed in an experiment studying the fusion-evaporation reaction 48Ca + 243Am at the GSI Helmholtzzentrum für Schwerionenforschung. The decay characteristics of the majority of these 30 chains are consistent with previous observations and interpretations of such chains to originate from isotopes of element Z = 115. High-resolution α-photon coincidence spectroscopy in conjunction with comprehensive Monte-Carlo simulations allow to propose excitation schemes of atomic nuclei of the heaviest elements, thereby probing nuclear structure models near the 'Island of Stability' with unprecedented experimental precision.

Two short-lived isotopes ^{221}U and ^{222}U were produced as evaporation residues in the fusion reaction ^{50}Ti+^{176}Yb at the gas-filled recoil separator TASCA. An α decay with an energy of E_{α}=9.31(5)  MeV and half-life T_{1/2}=4.7(7)  μs was attributed to ^{222}U. The new isotope ^{221}U was identified in α-decay chains starting with E_{α}=9.71(5)  MeV and T_{1/2}=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 α-decay reduced width.