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1. Selected spectroscopic results on element 115 decay chains

Author

Rudolph, D., Forsberg, U., Golubev, P., Sarmiento, L. G., Yakushev, A., Andersson, L.-L., Di Nitto, A., Düllmann, Ch. E., Gates, J. M., Gregorich, K. E., Gross, C. J., Herzberg, R.-D., Heßberger, F. P., Khuyagbaatar, J., Kratz, J. V., Rykaczewski, K., Schädel, M., Åberg, S., Ackermann, D., Block, M., Brand, H., Carlsson, B. G., Cox, D., Derkx, X., Eberhardt, K., Even, J., Fahlander, C., Gerl, J., Jäger, E., Kindler, B., Krier, J., Kojouharov, I., Kurz, N., Lommel, B., Mistry, A., Mokry, C., Nitsche, H., Omtvedt, J. P., Papadakis, P., Ragnarsson, I., Runke, J., Schaffner, H., Schausten, B., Thörle-Pospiech, P., Torres, T., Traut, T., Trautmann, N., Türler, A., Ward, A., Ward, D. E., and Wiehl, N.

Published
2015
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5. First chemical investigation of hassium (Hs, Z=108)

Author

Düllmann, Ch. E., Dressler, R., Eichler, B., Gäggeler, H. W., Glaus, F., Jost, D. T., Piguet, D., Soverna, S., Türler, A., Brüchle, W., Eichler, R., Jäger, E., Pershina, V., Schädel, M., Schausten, B., Schimpf, E., Schött, H. -J., Wirth, G., Eberhardt, K., Thörle, P., Trautmann, N., Ginter, T. N., Gregorich, K. E., Hoffman, D. C., Kirbach, U. W., Lee, D. M., Nitsche, H., Patin, J. B., Sudowe, R., Zielinski, P. M., Timokhin, S. N., Yakushev, A. B., Vahle, A., and Qin, Z.

Published
2003
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7. Chemical investigation of hassium (element 108)

Author

Dullmann, Ch. E., Bruchle, W., Dressler, R., Eberhardt, K., Eichler, B., Eichler, R., Gaggeler, H. W., Ginter, T. N., Glaus, F., Gregorich, K. E., Hoffman, D. C., Jager, E., Jost, D. T., Kirbach, U. W., Lee, D. M., Nitsche, H., Patin, J. B., Pershina, V., Piguet, D., Qin, Z., Schadel, M., Schausten, B., Schimpf, E., Schott, H.-J., Soverna, S., Sudowe, R., Thorle, P., Timokhin, S. N., Trautmann, N., Turler, A., Vahle, A., Wirth, G., Yakushev, A. B., and Zielinski, P. M.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Ch. E. Düllmann [1, 2]; W. Brüchle [3]; R. Dressler [2]; K. Eberhardt [4]; B. Eichler [2]; R. Eichler [2]; H. W. Gäggeler (corresponding author) [1, 2]; T. N. [...]

Published
2002
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9. Cold binary and ternary fragmentations in spontaneous fission of252Cf

Author

Ramayya, A. V., Hamilton, J. H., Hwang, J. K., Peker, L. K., Kormicki, J., Babu, B. R. S., Ginter, T. N., Sandulescu, A., Florescu, A., Carstoiu, F., Greiner, W., Ter-Akopian, G. M., Oganessian, Yu. Ts., Daniel, A. V., Ma, W. C., Varmette, P. G., Rasmussen, J. O., Asztalos, S. J., Chu, S. Y., Gregorich, K. E., Macchiavelli, A. O., Macleod, R. W., Cole, J. D., Aryaeinejad, R., Butler-Moore, K., Drigert, M. W., Stoyer, M. A., Bernstein, L. A., Lougheed, R. W., Moody, K. J., Prussin, S. G., Zhu, S. J., Griffin, H. C., and Donangelo, R.

Published
1997
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10. Gas phase chromatography of halides of elements 104 and 105

Author

Türler, A., Gäggeler, H. W., Gregorich, K. E., Barth, H., Brüchle, W., Czerwinski, K. R., Gober, M. K., Hannink, N. J., Henderson, R. A., Hoffman, D. C., Jost, D. T., Kacher, C. D., Kadkhodayan, B., Kovacs, J., Kratz, J. V., Kreek, S. A., Lee, D. M., Leyba, J. D., Nurmia, M. J., Schädel, M., Scherer, U. W., Schimpf, Vermeulen, D., Weber, A., Zimmermann, H. P., and Zvara, I.

Published
1992
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12. Chemical characterization of bohrium (element 107)

Author

Eichler, R., Brüchle, W., Dressler, R., Düllmann, Ch. E., Eichler, B., Gäggeler, H. W., Gregorich, K. E., Hoffman, D. C., Hübener, S., Jost, D. T., Kirbach, U. W., Laue, C. A., Lavanchy, V. M., Nitsche, H., Patin, J. B., Piguet, D., Schädel, M., Shaughnessy, D. A., Strellis, D. A., Taut, S., Tobler, L., Tsyganov, Y. S., Türler, A., Vahle, A., Wilk, P. A., and Yakushev, A. B.

Published
2000

13. Chemical properties of element 106 (seaborgium)

Author

Schädel, M., Brüchle, W., Dressler, R., Eichler, B., Gäggeler, H. W., Günther, R., Gregorich, K. E., Hoffman, D. C., Hübener, S., Jost, D. T., Kratz, J. V., Paulus, W., Schumann, D., Timokhin, S., Trautmann, N., Türler, A., Wirth, G., and Yakuschev, A.

Published
1997
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15. Decay spectroscopy of element 115 daughters: 280Rg →276Mt and 276Mt → 272Bth.

Author

Gates, J. M., Gregorich, K. E., Gothe, O. R., Uribe, E. C., Pang, G. K., Bleuel, D. L., Block, M., Clark, R. M., Campbell, C. M., Crawford, H. L., Cromaz, M., Di Nitto, A., Düllmann, Ch. E., Esker, N. E., Fahlander, C., Fallon, P., Farjadi, R. M., Forsberg, U., Khuyagbaatar, J., and Loveland, W.

Subjects
*DECAY chains, *SUPERHEAVY elements, *SPONTANEOUS fission, *X-ray spectroscopy, *COMPTON scattering, FLEROV Laboratory of Nuclear Reactions (Dubna, Russia)
Abstract

Forty-six decay chains, assigned to the decay of 288115, were produced using the 243Am)(48,3n)288115 reaction at the Lawrence Berkeley National Laboratory 88-in. cyclotron. The resulting series of α decays were studied using α-photon and α-x-ray spectroscopies. Multiple α-photon coincidences were observed in the element 115 decay chain members, particularly in the third- and fourth-generation decays (presumed to be 280Rg and 276Mt, respectively). Upon combining these data with those from 22 288115 decay chains observed in a similar experiment, updated level schemes in 276Mt and 272Bh (populated by the α decay of 280Rg and 276Mt, respectively) are proposed. Photons were observed in the energy range expected for K x rays coincident with the α decay of both 280Rg and 276Mt. However, Compton scattering of higher-energy γ rays and discrete transitions are present in the K x-ray region preventing a definitive Z identification to be made based on observation of characteristic K x-ray energies. [ABSTRACT FROM AUTHOR]

Published
2015
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16. ALPHA-PHOTON COINCIDENCE SPECTROSCOPY ALONG ELEMENT 115 DECAY CHAINS.

Author

RUDOLPH, D., FORSBERG, U., GOLUBEV, P., SARMIENTO, L. G., YAKUSHEV, A., ANDERSSON, L.-L., DI NITTO, A., DÜLLMANN, CH. E., GATES, J. M., GREGORICH, K. E., GROSS, C. J., HERZBERG, R.-D., HESSBERGER, F. P., KHUYAGBAATAR, J., KRATZ, J. V., RYKACZEWSKI, K., SCHÄDEL, M., ÅBERG, S., ACKERMANN, D., and BLOCK, M.

Subjects
DECAY chains, PHOTONS, AMERICIUM isotopes, CALCIUM isotopes, SPECTRUM analysis, NUCLEAR reactions, SEPARATION of gases
Abstract

Produced in the reaction 48Ca+ 243Am, thirty correlated α-decay chains were observed in an experiment conducted at the GSI Helmholzzentrum für Schwerionenforschung, Darmstadt, Germany. The decay chains are basically consistent with previous findings and are considered to originate from isotopes of element 115 with mass numbers 287, 288, and 289. A set-up aiming specifically for high-resolution charged particle and photon coincidence spectroscopy was placed behind the gas-filled separator TASCA. For the first time, γ rays as well as X-ray candidates were observed in prompt coincidence with the α-decay chains of element 115. [ABSTRACT FROM AUTHOR]

Published
2014
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17. FIRST EXPERIMENT AT TASCA TOWARDS X-RAY FINGERPRINTING OF ELEMENT 115 DECAY CHAINS.

Author

Forsberg, U., Golubev, P., Sarmiento, L. G., Jeppsson, J., Rudolph, D., Andersson, L.-L., Ackermann, D., Asai, M., Block, M., Eberhardt, K., Evend, J., Düllmann, Ch.E., Dvorak, J., Gates, J. M., Gregorich, K. E., Herzberg, R.-D., Hessberger, F. P., Jäger, E., Khuyagbaatar, J., and Kojouharov, I.

Subjects
PHYSICS experiments, X-rays, RADIOACTIVE decay, ATOMIC number, SUPERHEAVY elements, CALCIUM isotopes, NUCLEAR counters
Abstract

To identify the atomic number of superheavy nuclei produced in 48Ca-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 ionoptical 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 FROM AUTHOR]

Published
2012
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18. Chemical properties of the transactinide elements studied in liquid phase with SISAK.

Author

Omtvedt, J. P., Alstad, J., Bjørnstad, T., Düllmann, Ch. E., Gregorich, K. E., Hoffman, D. C., Nitsche, H., Opel, K., Polakova, D., Samadani, F., Schulz, F., Skarnemark, G., Stavsetra, L., Sudowe, R., and Zheng, L.

Subjects
LIQUIDS, EXTRACTION (Chemistry), ACTINIDE elements, EXPERIMENTS, SEPARATION (Technology)
Abstract

This article starts with a review of the current SISAK liquid-liquid extraction system, as used after the physical preseparator BGS at LBNL for chemical studies of transactinide elements. Emphasis will be on new additions and developments. Then the possibilities offered by the new TASCA separator at GSI and the use of actinide targets at both GSI and LBNL are discussed with respect to future SISAK transactinide experiments. Finally, current and future liquid-liquid extraction systems for studying elements Rf up to Hs are discussed. [ABSTRACT FROM AUTHOR]

Published
2008
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19. Cross-section limits for the 208Pb(86Kr,n)293118 reaction.

Author

Gregorich, K. E., Ginter, T. N., Loveland, W., Peterson, D., Patin, J. B., Folden, C. M., Hoffman, D. C., Lee, D. M., Nitsche, H., Omtvedt, J. P., Omtvedt, L. A., Stavsetra, L., Sudowe, R., Wilk, P. A., Zielinski, P. M., and Aleklett, K.

Subjects
*NUCLEAR cross sections, *ENERGY dissipation, *COLD fusion, *HEAVY nuclei, *PHYSICS
Abstract

In April-May, 2001, the previously reported experiment to synthesize element 118 using the 208Pb(86Kr,n)293118 reaction was repeated. No events corresponding to the synthesis of element 118 were observed with a total beam dose of 2.6 x 1018 ions. The simple upper-limit cross-sections (1 event) were 0.9 and 0.6 pb for evaporation residue magnetic rigidities of 2.00 Tm and 2.12 Tm, respectively. A more detailed cross-section calculation, accounting for an assumed narrow excitation function, the energy loss of the beam in traversing the target and the uncertainty in the magnetic rigidity of the Z = 118 recoils is also presented. Re-analysis of the primary data files from the 1999 experiment showed the reported element 118 events are not in the original data. The current results put constraints on the production cross-section for synthesis of very heavy nuclei in cold-fusion reactions. [ABSTRACT FROM AUTHOR]

Published
2003
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21. How good are superheavy element Z and A assignments?

Author

Gregorich Kenneth

Subjects
Physics, QC1-999
Abstract

Proton number, Z, and mass number,A, assignments for newly discovered heavy element nuclides have historically been made by observing α decay to a daughter with well-established Z and A, and then observing the well-know decay of that daughter. For all of the new superheavy element isotopes observed in 48Ca irradiations of actinide targets, this correlation technique has not been possible, because the α-decay chains end in spontaneous fission of previously unknown isotopes. Consequently, Z and A assignments have been made by less-direct means. The superheavy element Z and A assignment methods are summarized, and possibilities for how they may be incorrect are explored. While it is highly likely that most of the superheavy element Z and A assignments are correct, there is a real need for a direct proof.

Published
2016
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22. Spectroscopic Tools Applied to Element Z = 115 Decay Chains

Author

Forsberg U., Rudolph D., Golubev P., Sarmiento L.G., Yakushev A., Andersson L.-L., Nitto A. Di, Düllmann Ch.E., Gates J.M., Gregorich K.E., Gross C.J., Heßberger F.P., Herzberg R.-D., Khuyagbaatar J., Kratz J.V., Rykaczewski K., Schädel M., Åberg S., Ackermann D., Block M., Brand H., Carlsson B.G., Cox D., Derkx X., Eberhardt K., Even J., Fahlander C., Gerl J., Jäger E., Kindler B., Krier J., Kojouharov I., Kurz N., Lommel B., Mistry A., Mokry C., Nitsche H., Omtvedt J.P., Papadakis P., Ragnarsson I., Runke J., Schaffner H., Schausten B., Thörle-Pospiech P., Torres T., Traut T., Trautmann N., Türler A., Ward A., Ward D.E., and Wiehl and N.

Subjects
Physics, QC1-999
Abstract

Nuclides that are considered to be isotopes of element Z = 115 were produced in the reaction 48Ca + 243Am at the GSI Helmholtzzentrum für Schwerionenforschung Darmstadt. The detector setup TASISpec was used. It was mounted behind the gas-filled separator TASCA. Thirty correlated α-decay chains were found, and the energies of the particles were determined with high precision. Two important spectroscopic aspects of the offline data analysis are discussed in detail: the handling of digitized preamplified signals from the silicon strip detectors, and the energy reconstruction of particles escaping to upstream detectors relying on pixel-by-pixel dead-layer thicknesses.

Published
2014
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25. Identification of neutron h11/2 bands in 121,123Cd.

Author

Hwang, J. K., Beyer, C. J., Ramayya, A. V., Hamilton, J. H., Zhang, X. Q., Rasmussen, J. O., Luo, Y. X., Wu, S. C., Ginter, T. N., Lee, I. Y., Folden, C. M., Fallon, P., Zielinski, P., Gregorich, K. E., Macchiavelli, A. O., Stoyer, M., and Asztalos, S. J.

Published
2002
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26. High-spin states in neutron-rich even-even Pd isotopes.

Author

Butler-Moore, K., Aryaeinejad, R., Zhang, X. Q., Babu, B. R. S., Hamilton, J. H., Ramayya, A. V., Hwang, J. K., Oberacker, V. E., Zhu, S. J., Kormicki, J., Peker, L. K., Cole, J. D., Dardenne, Y. X., Ma, W. C., Asztalos, S. J., Chu, S. Y., Gregorich, K. E., Lee, I. Y., Mohar, M. F., and Rasmussen, J. O.

Published
1999
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32. Decay of the high-Jt isomeric state to a rotational band in 257Rf.

Author

Rissanen, J., Clark, R. M., Gregorich, K. E., Gates, J. M., Campbell, C. M., Crawford, H. L., Cromaz, M., Esker, N. E., Fallon, P., Forsberg, U., Gothe, O., Lee, I.-Y., Liu, H. L., Machiavelli, A. O., Mudder, P., Nitsche, H., Pang, G., Rice, A., Rudolph, D., and Stoyer, M. A.

Subjects
*NUCLEAR isomers, *NUCLEAR rotational states, *RUTHERFORDIUM, *NUCLEAR fusion, *NUCLEAR reactions, *ELECTRONS, LEAD isotope decay
Abstract

The 257Rf isotope has beéri populated via the 208Pb(50)Ti, n) fusion-evaporation reaction and delayed y-ray and electron decay spectroscopy has been performed. The existence of a high- K isomeric state in 257Rf has been confirmed. The isomeric state decays into a rotational band based on the 11/2-[725] excitation, which was observed up to spin of (23/2-). Three multipolarity-El y transitions depopulating the isomeric state have been observed, which fixes the spin for that state to (21/2+). This assignment agrees with theoretical predictions calculated with the microscopic-macroscopic approach, which suggest the isomeric state to be formed by coupling an unpaired 11/2- [725] quasineuiron to the (1/2-[521] ⊗ 9/2+[624])5- two-quasiproton state. The same two-quasiproton excitation is possible for the lowest isomer in 256Rf. [ABSTRACT FROM AUTHOR]

Published
2013
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33. Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in 254 Rf.

Author

David, H. M., Chen, J., Seweryniak, D., Kondev, F. G., Gates, J. M., Gregorich, K. E., Ahmad, I., Albers, M., Alcorta, M., Back, B. B., Baartman, B., Bertone, P. F., Bernstein, L. A., Campbell, C. M., Carpenter, M. P., Chiara, C. J., Clark, R. M., Cromaz, M., Doherty, D. T., and Dracoulis, D.

Subjects
*QUASIPARTICLES, *RADIOACTIVE decay, *FISSION neutrons, *NUCLEAR isomers, *ELECTROMAGNETISM, *GROUND state (Quantum mechanics)
Abstract

Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247(73) μs have been discovered in the heavy 254Rf nucleus. The observation of the shorter-lived isomer was made possible by a novel application of a digital data acquisition system. The isomers were interpreted as the Kπ = 8-, ν2(7/2+ [624], 9/2- [734]) two-quasineutron and the Kπ = 16+, 8-ν2(7/22 (7/2- [514], 9 /2+ [624]) four-quasiparticle configurations, respectively. Surprisingly, the lifetime of the two-quasiparticle isomer is more than 4 orders of magnitude shorter than what has been observed for analogous isomers in the lighter N= 150 isotones. The four-quasiparticle isomer is longer lived than the 254Rf ground state that decays exclusively∣ by spontaneous fission with a half-life of 23.2(1.1) μs. The absence of sizable fission branches from either of the isomers implies unprecedented fission hindrance relative to the ground state. [ABSTRACT FROM AUTHOR]

Published
2015
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35. Spectroscopy of Element 115 Decay Chains.

Author

Rudolph, D., Forsberg, U., Golubev, P., Sarmiento, L. G., Yakushev, A., Andersson, L.-L., Di Nitto, A., Düllmann, Ch. E., Gates, J. M., Gregorich, K. E., Gross, C. J., Heßberger, F. P., Herzberg, R.-D., Khuyagbaatar, J., Kratz, J. V., Rykaczewski, K., Schädel, M., Aberg, S., Ackermann, D., and Block, M.

Subjects
*X-rays, *SPECTRUM analysis, *MONTE Carlo method, *CHEMICAL reactions, *EVAPORATION (Chemistry)
Abstract

A high-resolution a, x-ray, and y-ray coincidence spectroscopy experiment was conducted at the GSI Helmholtzzentrum für Schwerionenforschung. Thirty correlated a-decay chains were detected following the fusion-evaporation reaction 48Ca + 243Am. The observations are consistent with previous assignments of similar decay chains to originate from element Z = 115. For the first time, precise spectroscopy allows the derivation of excitation schemes of isotopes along the decay chains starting with elements Z> 112. Comprehensive Monte Carlo simulations accompany the data analysis. Nuclear structure models provide a first level interpretation. [ABSTRACT FROM AUTHOR]

Published
2013
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36. First superheavy element experiments at the GSI recoil separator TASCA: The production and decay of element 114 in the 244Pu(48Ca,3-4n) reaction.

Author

Gates, J. M., Düllmann, Ch. E., Schädel, M., Yakushev, A., Türler, A., Eberhardt, K., Kratz, J. V., Ackermann, D., Andersson, L.-L., Block, M., Brüchle, W., Dvorak, J., Essel, H. G., Ellison, P. A., Even, J., Forsberg, U., Gellanki, J., Gorshkov, A., Graeger, R., and Gregorich, K. E.

Subjects
*SUPERHEAVY elements, *ISOTOPES, *ION bombardment, *COLLISIONAL excitation, *NUCLEAR cross sections, *ELECTRON-nucleus scattering
Abstract

Experiments with the new recoil separator, Transactinide Separator and Chemistry Apparatus (TASCA), at the GSI were performed by using beams of 48Ca to irradiate targets of 206-208Pb, which led to the production of 252-254No isotopes. These studies allowed for evaluation of the performance of TASCA when coupled to a new detector and electronics system. By following these studies, the isotopes of element 114 (288-291114) were produced in irradiations of 244Pu targets with 48Ca beams at compound nucleus excitation energies around 41.7 and 37.5 MeV, demonstrating TASCA's ability to perform experiments with picobarn-level cross sections. A total of 15 decay chains were observed and were assigned to the decay of 288-291114. A new α-decay branch in 281Ds was observed, leading to the new nucleus 277Hs. [ABSTRACT FROM AUTHOR]

Published
2011
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37. First Direct Measurements of Superheavy-Element Mass Numbers.

Author

Gates, J. M., Pang, G. K., Pore, J. L., Gregorich, K. E., Kwarsick, J. T., Savard, G., Esker, N. E., Covo, M. Kireeff, Mogannam, M. J., Batchelder, J. C., Bleuel, D. L., Clark, R. M., Crawford, H. L., Fallon, P., Hubbard, K. K., Hurst, A. M., Kolaja, I. T., Macchiavelli, A. O., Morse, C., and Orford, R.

Subjects
*SUPERHEAVY elements, *MASS (Physics)
Abstract

An experiment was performed at Lawrence Berkeley National Laboratory's 88-in. Cyclotron to determine the mass number of a superheavy element. The measurement resulted in the observation of two α-decay chains, produced via the 243Am(48Ca,xn)291-xMc reaction, that were separated by mass-to-charge ratio (A/q) and identified by the combined BGS+FIONA apparatus. One event occurred at A/q=284 and was assigned to 284Nh (Z=113), the α-decay daughter of 288Mc (Z=115), while the second occurred at A/q=288 and was assigned to 288Mc. This experiment represents the first direct measurements of the mass numbers of superheavy elements, confirming previous (indirect) mass-number assignments. [ABSTRACT FROM AUTHOR]

Published
2018
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