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101 results on '"Gregorich K"'

1. Towards the Discovery of New Elements: Production of Livermorium (Z=116) with 50Ti

Author

Gates, J. M., Orford, R., Rudolph, D., Appleton, C., Barrios, B. M., Benitez, J. Y., Bordeau, M., Botha, W., Campbell, C. M., Chadderton, J., Chemey, A. T., Clark, R. M., Crawford, H. L., Despotopulos, J. D., Dorvaux, O., Esker, N. E., Fallon, P., Folden III, C. M., Gall, B. J. P., Garcia, F. H., Golubev, P., Gooding, J. A., Grebo, M., Gregorich, K. E., Guerrero, M., Henderson, R. A., Herzberg, R. -D., Hrabar, Y., King, T. T., Covo, M. Kireeff, Kirkland, A. S., Krücken, R., Leistenschneider, E., Lykiardopoulou, E. M., McCarthy, M., Mildon, J. A., Müller-Gatermann, C., Phair, L., Pore, J. L., Rice, 1 E., Rykaczewski, K. P., Sammis, B. N., Sarmiento, L. G., Seweryniak, D., Sharp, D. K., Sinjari, A., Steinegger, P., Stoyer, M. A., Szornel, J. M., Thomas, K., Todd, D. S., Vo, P., Watson, V., and Wooddy, P. T.

Subjects
Nuclear Experiment
Abstract

The $^{244}$Pu($^{50}$Ti,$xn$)$^{294-x}$Lv reaction was investigated at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron facility. The experiment was aimed at the production of a superheavy element with $Z\ge 114$ by irradiating an actinide target with a beam heavier than $^{48}$Ca. Produced Lv ions were separated from the unwanted beam and nuclear reaction products using the Berkeley Gas-filled Separator and implanted into a newly commissioned focal plane detector system. Two decay chains were observed and assigned to the decay of $^{290}$Lv. The production cross section was measured to be $\sigma_{\rm prod}=0.44(^{+58}_{-28})$~pb at a center-of-target center-of-mass energy of 220(3)~MeV. This represents the first published measurement of the production of a superheavy element near the `Island-of-Stability', with a beam of $^{50}$Ti and is an essential precursor in the pursuit of searching for new elements beyond $Z=118$., Comment: Submitted to Physical Review Letters

Published
2024

2. On the half life of $^{71}$Ge and the Gallium Anomaly

Author

Norman, E. B., Drobizhev, A., Gharibyan, N., Gregorich, K. E., Kolomensky, Yu. G., Sammis, B. N., Scielzo, N. D., Shusterman, J. A., and Thomas, K. J.

Subjects
Nuclear Experiment
Abstract

Recent discussions about the origin of the Gallium Anomaly have motivated a remeasurement of the half life of $^{71}$Ge. We have conducted three separate measurements using dedicated planar Ge detectors: one with $^{55}$Fe as a standard, one with $^{57}$Co as a standard, and one stand alone 71Ge measurement. Our results yield a half life of 11.468 +- 0.008 days, which is consistent with but significantly more precise than the currently accepted value. With this experiment, the potential explanation of the Gallium Anomaly being due to an unexpectedly long $^{71}$Ge half life has been ruled out, leaving the origin of the anomaly as an open question., Comment: 9 pages, 4 figures

Published
2024

3. Heavy element formation in compound nucleus reactions with 238U targets

Author

Gregorich, K, Dullman, CE, Loveland, W, Folden, CM, Gates, Jacklyn, Garcia, MA, Sudowe, R, Stavestra, L, Dragojevic, I, Nelson, SL, Pang, GK, Zielinski, PM, Chung, YH, Eichler, R, Schaedel, M, Teurler, A, Yakushev, A, Dvorak, J, Hoffman, DC, and Nitsche, H

Published
2023

4. Heavy element formation in compound nucleus reactions with 238U targets

Author

Gregorich, K, Dullman, CE, Loveland, W, Folden, CM, Gates, Jacklyn, Garcia, MA, Sudowe, R, Stavestra, L, Dragojevic, I, Nelson, SL, Pang, GK, Zielinski, PM, Chung, YH, Eichler, R, Schaedel, M, Teurler, A, Yakushev, A, Dvorak, J, Hoffman, DC, and Nitsche, H

Published
2021

5. Recoil-alpha-fission and recoil-alpha-alpha-fission events observed in the reaction Ca-48 + Am-243

Author

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

Subjects
Nuclear Experiment
Abstract

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 f\"ur Schwerionenforschung. 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 are similar to four such events reported from experiments performed at the Dubna gas-filled separator. Contrary to their interpretation, we propose an alternative view, namely to assign eight of these eleven decay chains of recoil-alpha(-alpha)-fission type to start from the 3n-evaporation channel 115-288. The other three decay chains remain viable candidates for the 2n-evaporation channel 115-289., Comment: 15 pages. Article: 9 pages, 3 tables, 3 figures. Supplemental material: 6 pages, 7 tables, 1 figure. Submitted to PRC

Published
2015
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6. Search for Oscillation of the Electron-Capture Decay Probability of $^{142}$Pm

Author

Vetter, P. A., Clark, R. M., Dvorak, J., Freedman, S. J., Gregorich, K. E., Jeppesen, H. B., Mittelberger, D., and Wiedeking, M.

Subjects
Nuclear Experiment
Abstract

We have searched for time modulation of the electron capture decay probability of $^{142}$Pm in an attempt to confirm a recent claim from a group at the Gesellschaft f\"{u}r Schwerionenforschung (GSI). We produced $^{142}$Pm via the $^{124}$Sn($^{23}$Na, 5n)$^{142}$Pm reaction at the Berkeley 88-Inch Cyclotron with a bombardment time short compared to the reported modulation period. Isotope selection by the Berkeley Gas-filled Separator is followed by implantation and a long period of monitoring the $^{142}$Nd K$_{\alpha}$ x-rays from the daughter. The decay time spectrum of the x-rays is well-described by a simple exponential and the measured half-life of 40.68(53) seconds is consistent with the accepted value. We observed no oscillatory modulation at the proposed frequency at a level 31 times smaller than that reported by Litvinov {\it et al.} (Phys. Lett. B 664 (2008) 162; arXiv:0801.2079 [nucl-ex]). A literature search for previous experiments that might have been sensitive to the reported modulation uncovered another example in $^{142}$Eu electron-capture decay. A reanalysis of the published data shows no oscillatory behavior., Comment: 12 pages (double-spaced), 6 figures

Published
2008
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7. Cross Section Limits for the $^{208}$Pb($^{86}$Kr,n)$^{293}$118 Reaction

Author

Gregorich, K. E., Ginter, T. N., Loveland, W., Peterson, D., Patin, J. B., Folden III, 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 Experiment
Abstract

In April-May, 2001, the previously reported experiment to synthesize element 118 using the $^{208}$Pb($^{86}$Kr,n)$^{293}$118 reaction was repeated. No events corresponding to the synthesis of element 118 were observed with a total beam dose of 2.6 x 10$^{18}$ ions. The simple upper limit cross sections (1 event) were 0.9 and 0.6 pb for evaporation residue magnetic rigidities of 2.00 $T m$ and 2.12 $T m$, 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., Comment: 7 pages, 2 figures. Submitted to EPJA

Published
2002
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8. Search for the Production of Element 112 in the 48Ca + 238U Reaction

Author

Loveland, W., Gregorich, K. E., Patin, J. B., Peterson, D., Rouki, C., Zielinski, P. M., and Aleklett, K.

Subjects
Nuclear Experiment
Abstract

We have searched for the production of element 112 in the reaction of 231 MeV 48Ca with 238U. We have not observed any events with a "one event" upper limit cross section of 1.6 pb for EVR-fission events and 1.8 pb for EVR-alpha events., Comment: 6 pages, 3 figures, submitted to Phys. Rev. C

Published
2002
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9. Non-Observation of the Production of Superheavy Nuclei in the Reaction of $^{86]$Kr with $^{208}$Pb

Author

Gregorich, K. E., Loveland, W., Ghiorso, A., Hoffman, D. C., Lee, D. M., Nitsche, H., Swiatecki, W. J., Kirbach, U. W., Laue, C. A., Adams, J. L., Patin, J. B., Shaughnessy, D. A., Strellis, D. A., and Wilk, P. A.

Subjects
Nuclear Experiment
Abstract

The published claim for the discovery of element 118 is retracted., Comment: 1 page, paper accepted for publication in PRL, will not be published

Published
2002

10. Heavy element formation in compound nucleus reactions with 238U targets

Author

Gregorich, K, Gregorich, K, Dullman, CE, Loveland, W, Folden, CM, Gates, Jacklyn, Garcia, MA, Sudowe, R, Stavestra, L, Dragojevic, I, Nelson, SL, Pang, GK, Zielinski, PM, Chung, YH, Eichler, R, Schaedel, M, Teurler, A, Yakushev, A, Dvorak, J, Hoffman, DC, Nitsche, H, Gregorich, K, Gregorich, K, Dullman, CE, Loveland, W, Folden, CM, Gates, Jacklyn, Garcia, MA, Sudowe, R, Stavestra, L, Dragojevic, I, Nelson, SL, Pang, GK, Zielinski, PM, Chung, YH, Eichler, R, Schaedel, M, Teurler, A, Yakushev, A, Dvorak, J, Hoffman, DC, and Nitsche, H

Published
2022

11. Evidence for the Synthesis of Element 110 Produced by the 59Co+209Bi Reaction

Author

Ghiorso, A., Lee, D., Somerville, P., Loveland, W., Nitschke, M., Ghiorso, W., Seaborg, G.T., Wilmarth, P.A., Leres, R., Wydler, A., Nurmia, M.J., Gregorich, K., Gaylord, R., Hamilton, T., Hannink, N.J., Hoffman, D.C., Jarzynski, C., Kacher, C., Kadkhodayan, B., Kreek, S., Lane, M., Lyon, A., McMahan, M.A., Neu, M., Sikkeland, T., Swiatecki, W.J., Turler, A., Walton, J.T., and Yashita, S.

Published
1994

13. Fusion reaction Ca 48 + Bk 249 leading to formation of the element Ts (Z=117)

Author

Khuyagbaatar J., Yakushev A., Dullmann 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., Hubner A., Jager 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., Rudolph D., Runke J., Rykaczewski K. P., Sarmiento L. G., Schadel M., Schausten B., Semchenkov A., Shaughnessy D. A., Steinegger P., Steiner J., Tereshatov E. E., Thorle-Pospiech P., Tinschert K., Torres De Heidenreich T., Trautmann N., Turler A., Uusitalo J., Ward D. E., Wegrzecki M., Wiehl N., Van Cleve S. M., Yakusheva V., Khuyagbaatar, J., Yakushev, A., Dullmann, 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., Hubner, A., Jager, 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., Rudolph, D., Runke, J., Rykaczewski, K. P., Sarmiento, L. G., Schadel, M., Schausten, B., Semchenkov, A., Shaughnessy, D. A., Steinegger, P., Steiner, J., Tereshatov, E. E., Thorle-Pospiech, P., Tinschert, K., Torres De Heidenreich, T., Trautmann, N., Turler, A., Uusitalo, J., Ward, D. E., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., and Yakusheva, V.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

The heaviest currently known nuclei, which have up to 118 protons, have been produced in Ca48 induced reactions with actinide targets. Among them, the element tennessine (Ts), which has 117 protons, has been synthesized by fusing Ca48 with the radioactive target Bk249, which has a half-life of 327 d. The experiment was performed at the gas-filled recoil separator TASCA. Two long and two short α decay chains were observed. The long chains were attributed to the decay of Ts294. 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 Ts293. 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.

Published
2019

14. 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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15. 117番元素Ts合成のための48Ca+249Bk融合反応

Author

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., Rudolph, D., Runke, J., Rykaczewski, K. P., Sarmiento, L. G., Schädel, M., Schausten, B., Semchenkov, A., Shaughnessy, D. A., Steinegger, P., Steiner, J., Tereshatov, E. E., Thörle-Pospiech, P., Tinschert, K., Torres De Heidenreich, T., Trautmann, N., Türler, A., Uusitalo, J., Ward, D. E., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., and Yakusheva, V.

Subjects
gas-filled separator, superheavy elements, element 117 (Ts), alpha decay, Subatomic Physics, Nuclear Theory, low and intermediate energy heavy-ion reactions, ydinfysiikka, Nuclear Experiment, nuclear structure and decays
Abstract

We have performed an experiment to synthesize the element 117 (Ts) with the $^{48}$Ca+$^{249}$Bk fusion reaction. Four $\alpha$-decay chains attributed to the element 117 were observed. Two of them were long decay chains which can be assigned to the one originating from the $\alpha$ decay of $^{294}$Ts. The other two were short decay chains which are consistent with the one originating from the $\alpha$ decay of $^{293}$Ts. We have compared the present results with the literature data, and found that our present results mostly confirmed the literature data, leading to the firm confirmation of the synthesis of the element 117., $^{48}$Ca+$^{249}$B融合反応を用いて117番元素(Ts)合成実験を行い、117番元素に起因すると思われる4つの$\alpha$崩壊連鎖を観測した。うち2つは長い崩壊連鎖で、$^{294}$Tsの$\alpha$崩壊に起因するものと同定された。他の2つは短い崩壊連鎖で、$^{293}$Tsの$\alpha$崩壊に起因すると考えると矛盾しない。今回の結果と過去の文献値を比較したところ、今回の我々の結果は過去の文献値をほぼ再現し、117番元素合成の事実を強く再確認する結果となった。

Published
2019

16. Search for elements 119 and 120

Author

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. K., Mokry, C., Nitsche, H., Omtvedt, J. P., Pang, G. K., Papadakis, P., Renisch, D., Roberto, J. B., Rudolph, D., Runke, J., Rykaczewski, K. P., Sarmiento Pico, Luis, Schädel, M., Schausten, B., Semchenkov, A., Shaughnessy, D. A., Steinegger, P., Steiner, J., Tereshatov, E. E., Thörle-Pospiech, P., Tinschert, K., Torres De Heidenreich, T., Trautmann, N., Türler, A., Uusitalo, J., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., Yakusheva, V., 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. K., Mokry, C., Nitsche, H., Omtvedt, J. P., Pang, G. K., Papadakis, P., Renisch, D., Roberto, J. B., Rudolph, D., Runke, J., Rykaczewski, K. P., Sarmiento Pico, Luis, Schädel, M., Schausten, B., Semchenkov, A., Shaughnessy, D. A., Steinegger, P., Steiner, J., Tereshatov, E. E., Thörle-Pospiech, P., Tinschert, K., Torres De Heidenreich, T., Trautmann, N., Türler, A., Uusitalo, J., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., and Yakusheva, V.

Abstract

A search for production of the superheavy elements with atomic numbers 119 and 120 was performed in the 50Ti+249Bk and 50Ti+249Cf fusion-evaporation reactions, respectively, at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. Over four months of irradiation, the 249Bk target partially decayed into 249Cf, which allowed for a simultaneous search for both elements. Neither was detected at cross-section sensitivity levels of 65 and 200 fb for the 50Ti+249Bk and 50Ti+249Cf reactions, respectively, at a midtarget beam energy of Elab = 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.

Published
2020

17. 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

18. 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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19. Low-lying states in 219Ra and 215Rn : Sampling microsecond α-decaying nuclei

Author

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

Subjects
alpha decay, gamma-ray spectroscopy, nuclear shell model, pulse shape analysis, Subatomic Physics, half life, Nilsson-Strutinsky calculations
Abstract

Short-lived α-decaying nuclei "northeast" of 208Pb in the chart of nuclides were studied using the reaction 48Ca+243Am 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 220Ra and its odd-A neighbors, 219Fr, and 219,221Ra, with a focus on the 219Ra→215Rn decay, were studied by means of α-γ spectroscopy. A revised α-decay scheme of 219Ra 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.

Published
2018

20. Study of non-fusion products in the 50Ti+249Cf reaction

Author

Di Nitto, A., Khuyagbaatar, J., Ackermann, D., Andersson, L.-L., Badura, E., Block, M., Brand, H., Conrad, I., Cox, D. M., Düllmann, Ch. E., Dvorak, J., Eberhardt, K., Ellison, P. A., Esker, N. E., Even, J., Fahlander, C., Forsberg, U., Gates, J. M., Golubev, P., Gothe, O., Gregorich, K. E., Hartmann, W., Herzberg, R. D., Heßberger, F. P., Hoffmann, J., Hollinger, R., Hübner, A., Jäger, E., Kindler, B., Klein, S., Kojouharov, I., Kratz, J. V., Krier, J., Kurz, N., Lahiri, S., Lommel, B., Maiti, M., Mändl, R., Merchán, E., Minami, S., Mistry, A. K., Mokry, C., Nitsche, H., Omtvedt, J. P., Pang, G. K., Renisch, D., Rudolph, D., Runke, J., Sarmiento, L. G., Schädel, M., and Research unit Nuclear & Hadron Physics

Subjects
COLLISIONS, PROBABILITY, CA-48+CM-248, production of radioactive nuclei, U-238, ELEMENTS, ISOTOPES, MULTINUCLEON TRANSFER-REACTIONS, HEAVY, Nuclear Experiment, FISSION, BARRIER
Abstract

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.

Published
2018

21. Fusion reaction 48Ca + 249Bk leading to formation of the element Ts (Z=117)

Author

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., Rudolph, D., Runke, J., Rykaczewski, K. P., Sarmiento, L. G., Schädel, M., Schausten, B., Semchenkov, A., Shaughnessy, D. A., Steinegger, P., Steiner, J., Tereshatov, E. E., Thörle-Pospiech, P., Tinschert, K., Torres De Heidenreich, T., Trautmann, N., Türler, A., Uusitalo, J., Ward, D. E., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., Yakusheva, V., 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., Rudolph, D., Runke, J., Rykaczewski, K. P., Sarmiento, L. G., Schädel, M., Schausten, B., Semchenkov, A., Shaughnessy, D. A., Steinegger, P., Steiner, J., Tereshatov, E. E., Thörle-Pospiech, P., Tinschert, K., Torres De Heidenreich, T., Trautmann, N., Türler, A., Uusitalo, J., Ward, D. E., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., and Yakusheva, V.

Abstract

The heaviest currently known nuclei, which have up to 118 protons, have been produced in 48Ca induced reactions with actinide targets. Among them, the element tennessine (Ts), which has 117 protons, has been synthesized by fusing 48Ca with the radioactive target 249Bk, which has a half-life of 327 d. The experiment was performed at the gas-filled recoil separator TASCA. Two long and two short α decay chains were observed. The long chains were attributed to the decay of 294Ts. 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 293Ts. 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.

Published
2019

22. Study of non-fusion products in the 50Ti + 249Cf reaction

Author

Di Nitto, Antonio, Khuyagbaatar, J., Ackermann, Dieter, Andersson, L.-L., Badura, E., Block, M., Brand, H., Conrad, I., Cox, D. M., Düllmann, Christoph Emanuel, Dvorak, Jan, Eberhardt, K., Ellison, P. A., Esker, N. E., Even, Julia, Fahlander, C., Forsberg, U., Gates, J. M., Golubev, P., Gothe, O., Gregorich, K. E., Hartmann, W., Herzberg, R. D., Heßberger, F., Hoffmann, J., Hollinger, R., Hübner, A., Jäger, E., Kindler, B., Klein, S., Kojouharov, I., Kratz, J. V., Krier, J., Kurz, N., Lahiri, S., Lommel, B., Maiti, M., Mändl, R., Merchán, E., Minami, S., Mistry, A. K., Mokry, C., Nitsche, H., Omtvedt, J. P., Pang, G. K., Renisch, D., Rudolph, D., Runke, J., Sarmiento, L. G., Schädel, M., Schaffner, H., Schausten, B., Semchenkov, A., Steiner, J., Thörle-Pospiech, P., Trautmann, N., Türler, A., Uusitalo, J., Ward, D., Wegrzecki, M., Wieczorek, P., Wiehl, N., Yakushev, A., and Yakusheva, V.

Subjects
ydinreaktiot, production of radioactive nuclei, ddc:530, multi-nucleon transfer reactions, quasifission, Nuclear Experiment, α decay, ydinfysiikka
Abstract

Physics letters / B B 784, 199 - 205 (2018). doi:10.1016/j.physletb.2018.07.058, Published by North-Holland Publ., Amsterdam

Published
2018
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24. Recoil-α-fission and recoil-α-α-fission events observed in the reaction 48Ca + 243Am

Author

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

Subjects
Quantum Physics, Uup, alpha decay, Superheavy elements, Spontaneous fission, Molecular, nucl-ex, Nuclear & Particles Physics, Atomic, Particle and Plasma Physics, Nuclear, Element 115, Nuclear Experiment, Astronomical and Space Sciences
Abstract

Products of the fusion-evaporation reaction 48Ca + 243Am were studied with the TASISpec set-up at the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. Amongst the detected thirty correlated α-decay chains associated with the production of element Z=115, two recoil-α-fission and five recoil-α-α-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 289115 due to the fact that these recoil-α-α-fission events were observed only at low excitation energies. Contrary to this interpretation, we suggest that some of these recoil-α-α-fission decay chains, as well as some of the recoil-α-α-fission and recoil-α-fission decay chains reported from Berkeley and in this article, start from the 3n-evaporation channel 288115.

Published
2016

25. Recoil-alpha-fission and recoil-alpha-alpha-fission events observed in the reaction Ca-48+Am-243

Author

Forsberg, U., Rudolph, D., Andersson, L. -L., Di Nitto, A., D��llmann, Ch. E., Gates, J. M., Golubev, P., Gregorich, K. E., Gross, C. J., Herzberg, R. -D., Hessberger, F. P., Khuyagbaatar, J., Kratz, J. V., Rykaczewski, K., Sarmiento, L. G., Sch��del, M., Yakushev, A., ��berg, S., Ackermann, D., Block, M., Brand, H., Carlsson, B. G., Cox, D., Derkx, X., Dobaczewski, J., Eberhardt, K., Even, J., Fahlander, C., Gerl, J., J��ger, E., Kindler, B., Krier, J., Kojouharov, I., Kurz, N., Lommel, B., Mistry, A., Mokry, C., Nazarewicz, W., Nitsche, H., Omtvedt, J. P., Papadakis, P., Ragnarsson, I., Runke, J., Schaffner, H., Schausten, B., Shi, Y., Th��rle-Pospiech, P., Torres, T., Traut, T., Trautmann, N., T��rler, A., Ward, A., Ward, D. E., Wiehl, N., and Research unit Nuclear & Hadron Physics

Subjects
SPECTROSCOPY, Uup, alpha decay, NUCLEI, Superheavy elements, Spontaneous fission, FOS: Physical sciences, SEPARATOR, nucl-ex, HEAVIEST ELEMENTS, CHEMISTRY, SIMULATION, TASCA, Element 115, Nuclear Experiment (nucl-ex), HEAVY, Nuclear Experiment, 115 DECAY CHAINS
Abstract

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 f\"ur Schwerionenforschung. 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 are similar to four such events reported from experiments performed at the Dubna gas-filled separator. Contrary to their interpretation, we propose an alternative view, namely to assign eight of these eleven decay chains of recoil-alpha(-alpha)-fission type to start from the 3n-evaporation channel 115-288. The other three decay chains remain viable candidates for the 2n-evaporation channel 115-289., Comment: 15 pages. Article: 9 pages, 3 tables, 3 figures. Supplemental material: 6 pages, 7 tables, 1 figure. Submitted to PRC

Published
2016

26. Decay spectroscopy of element 115 daughters:Rg280→Mt276andMt276→Bh272

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, C.-H. E., Esker, N. E., Fahlander, C., Fallon, P., Farjadi, R. M., Forsberg, U., Khuyagbaatar, J., Loveland, W., Macchiavelli, A. O., May, E. M., Mudder, P. R., Olive, D. T., Rice, A. C., Rissanen, J., Rudolph, D., Sarmiento, L. G., Shusterman, J. A., Stoyer, M. A., Wiens, A., Yakushev, A., and Nitsche, H.

Abstract

Forty-six decay chains, assigned to the decay of 115288, were produced using the Am243(Ca48,3n)115288 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 Rg280 and Mt276, respectively). Upon combining these data with those from 22 115288 decay chains observed in a similar experiment, updated level schemes in Mt276 and Bh272 (populated by the α decay of Rg280 and Mt276, respectively) are proposed. Photons were observed in the energy range expected for K x rays coincident with the α decay of both Rg280 and Mt276. 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.

Published
2015

27. Gas Phase Chromatography Experiments with Bromides of Tantalum and Element 105

Author

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

Published
2017

28. Decay Spectroscopy of Element 115 Daughters: 280Rg -> 276Mt and 276Mt -> 272Bh

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, Claes, Fallon, P., Farjadi, R. M., Forsberg, Ulrika, Khuyagbaatar, J., Loveland, W., Macchiavelli, A. O., May, E. M., Mudder, P. R., Olive, D. T., Rice, A. C., Rissanen, J., Rudolph, Dirk, Sarmiento, Luis, Shusterman, J. A., Stoyer, M. A., Wiens, A., Yakushev, A., and Nitsche, H.

Subjects
Subatomic Physics
Abstract

Forty-six decay chains, assigned to the decay of 288-115, were produced using the 243Am(48Ca,3n)288-115 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 22 288-115 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.

Published
2015

29. Element 115 studied with TASISpec

Author

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

Subjects
Physics
Abstract

GSI Scientific Report 2013 - GSI Report 2014-1

Published
2014
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30. 48Ca+249Bk Fusion Reaction Leading to Element Z=117: Long-Lived α-Decaying 270Db and Discovery of 266Lr

Author

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, Claes, Forsberg, Ulrika, Gates, J. M., Gharibyan, N., Golubev, Pavel, 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., Rudolph, Dirk, Runke, J., Rykaczewski, K. P., Sarmiento, Luis, Schädel, M., Schausten, B., Semchenkov, A., Shaughnessy, D. A., Steinegger, P., Steiner, J., Tereshatov, E. E., Thörle-Pospiech, P., Tinschert, K., Torres De Heidenreich, T., Trautmann, N., Türler, A., Uusitalo, J., Ward, D. E., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., and Yakusheva, V.

Subjects
superheavy elements, element 117, Subatomic Physics, alpha-decay
Abstract

The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-μs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."

Published
2014

31. Study of the $^{48}Ca + ^{249}Bk$ fusion reaction leading to element $Z = 117$: long-lived $\alpha$-decaying $^{270}Db$ and discovery of $^{266}Lr$

Author

Khuyagbaatar, J., Yakushev, A., Düllmann, C. 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., 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., Rudolph, D., Runke, J., Rykaczewski, K., Sarmiento, L. G., Schädel, M., Schausten, B., Semchenkov, A., Shaughnessy, D. A., Steinegger, P., Steiner, J., Tereshatov, E. E., Thörle-Pospiech, P., Tinschert, K., Torres De Heidenreich, T., Trautmann, N., Türler, A., Uusitalo, J., Ward, D. E., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., and Yakusheva, V.

Subjects
Physics
Abstract

GSI Scientific Report 2013 - GSI Report 2014-1

Published
2014
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32. The Superheavy Element Search Campaigns at TASCA

Author

Khuyagbaatar, J., Yakushev, A., Düllmann, C. E., Nitsche, H., Roberto, J., Ackermann, D., L Andersson, L., Asai, M., Brand, H., Block, M., Cox, D. M., Dasgupta, M., Derkx, X., Di Nitto, A., Dvorak, J., Eberhardt, K., Ellison, P. A., Esker, N. E., Even, J., Evers, M., Claes Fahlander, Ulrika Forsberg, Gates, J. M., Gharibyan, N., Gregorich, K. E., Pavel Golubev, Gothe, O., Hamilton, J. H., Hinde, D. J., Willi Hartmann, D Herzberg, R., Fritz-Peter Hessberger, Hoffmann, J., Hollinger, R., Hübner, A., Jäger, E., Jeppsson, J., Kindler, B., Klein, S., Kojouharov, I., Kratz, J. V., Krier, J., Kurz, N., Lahiri, S., Lommel, B., Maiti, M., Miernik, K., Minami, S., Mistry, A., Mokry, C., Omtvedt, J. P., Pang, G. K., Papadakis, P., Pysmenetska, I., Renisch, D., Dirk Rudolph, Runke, J., Rykaczewski, K., Luis Sarmiento, Schädel, M., Schausten, B., Shaughnessy, D. A., Semchenkov, A., Steiner, J., Steinegger, P., Thörle-Pospiech, P., Tereshatov, E. E., Torres Heidenreich, T., Trautmann, N., Türler, A., Uusitalo, J., Daniel Ward, Wiehl, N., Wegrzecki, M., and Yakusheva, V.

Published
2013

33. Decay of the High-K 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, Ulrika, Gothe, O., Lee, I. -Y., Liu, H. L., Machiavelli, A. O., Mudder, P., Nitsche, H., Pang, G., Rice, A., Rudolph, Dirk, Stoyer, M. A., Wiens, A., and Xu, F. R.

Subjects
Subatomic Physics
Abstract

The 257Rf isotope has been populated via the 208Pb(50Ti, n) fusion-evaporation reaction and delayed gamma-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-E1 gamma 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] quasineutron to the (1/2(-)[521] circle times 9/2(+)[624])(5)- two-quasiproton state. The same two-quasiproton excitation is possible for the lowest isomer in 256Rf.

Published
2013

34. 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., Duellmann, Ch E., Schaedel, M., Yakushev, A., Tuerler, A., Eberhardt, K., Kratz, J. V., Ackermann, D., Andersson, L. -L., Block, M., Bruechle, W., Dvorak, J., Essel, H. G., Ellison, P. A., Even, J., Forsberg, Ulrika, Gellanki, Jnaneswari, Gorshkov, A., Graeger, R., Gregorich, K. E., Hartmann, W., Herzberg, R. -D., Hessberger, F. P., Hild, D., Huebner, A., Jaeger, E., Khuyagbaatar, J., Kindler, B., Krier, J., Kurz, N., Lahiri, S., Liebe, D., Lommel, B., Maiti, M., Nitsche, H., Omtvedt, J. P., Parr, E., Rudolph, Dirk, Runke, J., Schaffner, H., Schausten, B., Schimpf, E., Semchenkov, A., Steiner, J., Thoerle-Pospiech, P., Uusitalo, J., Wegrzecki, M., and Wiehl, N.

Subjects
Subatomic Physics
Abstract

Experiments with the new recoil separator, Transactinide Separator and Chemistry Apparatus (TASCA), at the GSI were performed by using beams of Ca-48 to irradiate targets of Pb206-208, which led to the production of No252-254 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 ((288-291)114) were produced in irradiations of Pu-244 targets with Ca-48 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 a-decay branch in (281)Ds was observed, leading to the new nucleus (277)Hs.

Published
2011

35. Independent Verification of Element 114 Production in the Ca 48 + Pu 242 Reaction

Author

Stavsetra, L., Gregorich, K. E., Dvorak, J., Ellison, P. A., Dragojević, I., Garcia, M. A., and Nitsche, H.

Abstract

Independent verification of the production of element 114 in the reaction of 244-MeV Ca48 with Pu242 is presented. Two chains of time- and position-correlated decays have been assigned to 128614 and 128714. The observed decay modes, half-lives, and decay energies agree with published results. The measured cross sections at a center-of-target energy of 244 MeV for the Pu242(Ca48,3–4n)1287,28614 reactions were 1.4−1.2+3.2 pb each, which are lower than the reported values.

Published
2009

36. Excitation function for the production ofBh262(Z=107) in the odd-Z-projectile reactionPb208(Mn55,n)

Author

Folden Iii, C. M., Nelson, S. L., Düllmann, C.-H. E., Schwantes, J. M., Sudowe, R., Zielinski, P. M., Gregorich, K. E., Nitsche, H., and Hoffman, D. C.

Subjects
Nuclear Experiment
Abstract

The excitation function for production of Bh262 in the odd-Z-projectile reaction Pb208(Mn55, n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from Bh262 and 2 decay chains originating from Bh261 were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540−150+180 pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than five times larger than that expected based on previously reported results for production of Bh262 in the analogous even-Z-projectile reaction Bi209(Cr54, n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the optimum energy rule proposed by Świątecki, Siwek-Wilczyńska, and Wilczyński.

Published
2006

37. Confirmation of production of element 110 by the 208 Pb ( 64 Ni , n ) reaction

Author

Ginter, T. N., Gregorich, K. E., Loveland, W., Lee, D. M., Kirbach, U. W., Sudowe, R., Folden, C. M., Patin, J. B., Seward, N., Wilk, P. A., Zielinski, P. M., Aleklett, K., Eichler, R., Nitsche, H., and Hoffman, D. C.

Abstract

We report the experimental confirmation of the production of element 110. In the bombardment of a 208Pb target with a 309-MeV 64Ni beam, we have observed two chains of time- and position-correlated events. Each chain consisted of the implantation of an evaporation residue followed by the emission of α particles. We attribute these two chains to the decay of 271110 produced with a cross section of 8.3−5.3+11pb.

Published
2003

38. First Experiment at TASCA Towards X-Ray Fingerprinting of Element 115 Decay Chains

Author

Forsberg, Ulrika, Golubev, Pavel, Sarmiento, L. G., Jeppsson, Johan, Rudolph, Dirk, Andersson, L. -L., Ackermann, D., Asai, M., Block, M., Eberhardt, K., Even, J., Düllmann, Ch. E., Dvorak, J., Gates, J. M., Gregorich, K. E., Herzberg, R. -D., Heßberger, F. P., Jäger, E., Khuyagbaatar, J., Kojouharov, I., Kratz, J. V., Krier, J., Kurz, N., Lahiri, S., Lommel, B., Maiti, M., Merchan, E., Omtvedt, J. P., Parr, E., Runke, J., Schaffner, H., Schädel, M., Yakushev, A., Forsberg, Ulrika, Golubev, Pavel, Sarmiento, L. G., Jeppsson, Johan, Rudolph, Dirk, Andersson, L. -L., Ackermann, D., Asai, M., Block, M., Eberhardt, K., Even, J., Düllmann, Ch. E., Dvorak, J., Gates, J. M., Gregorich, K. E., Herzberg, R. -D., Heßberger, F. P., Jäger, E., Khuyagbaatar, J., Kojouharov, I., Kratz, J. V., Krier, J., Kurz, N., Lahiri, S., Lommel, B., Maiti, M., Merchan, E., Omtvedt, J. P., Parr, E., Runke, J., Schaffner, H., Schädel, M., and Yakushev, A.

Abstract

To identify the atomic number of superheavy nuclei produced in Ca-48-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.

Published
2012

39. Evidence for New Isotopes of Element 107: B 266 h and B 267 h

Author

Wilk, P. A., Gregorich, K. E., Türler, A., Laue, C. A., Eichler, R., Ninov, V., Adams, J. L., Kirbach, U. W., Lane, M. R., Lee, D. M., Patin, J. B., Shaughnessy, D. A., Strellis, D. A., Nitsche, H., and Hoffman, D. C.

Abstract

New neutron rich isotopes 107267Bh and 107266Bh were produced in bombardments of a 249Bk target with 117-MeV and 123-MeV 22Ne ions at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Identification was made by observation of correlated α-particle decays between the Bh isotopes and their Db and Lr daughters using a rotating wheel system. 267Bh was produced with a cross section of ≈70 pb and decays with a 17−6+14 s half life by emission of α particles with an average energy of 8.83±0.03 MeV. One atom of 266Bh was observed, decaying within 1 s by emission of a 9.29-MeV α particle.

Published
2000

40. Observation of Superheavy Nuclei Produced in the Reaction of K 86 r with P 208 b

Author

Ninov, V., Gregorich, K. E., Loveland, W., Ghiorso, A., Hoffman, D. C., Lee, D. M., Nitsche, H., Swiatecki, W. J., Kirbach, U. W., Laue, C. A., Adams, J. L., Patin, J. B., Shaughnessy, D. A., Strellis, D. A., and Wilk, P. A.

Abstract

Following a prediction by Smolańczuk [Phys. Rev. C 59, 2634 (1999)], we searched for superheavy element formation in the bombardment of 208Pb with 449-MeV 86Kr ions. We have observed three decay chains, each consisting of an implanted heavy atom and six subsequent α decays, correlated in time and position. In these decay chains, a rapid (ms) sequence of high energy α particles ( Eα≥10MeV) indicates the decay of a new high- Z element. The observed chains are consistent with the formation of 129318 and its decay by sequential α-particle emission to 128916, 128514, 128112, 127710, 273Hs ( Z=108) and 269Sg ( Z=106). The production cross section is 2.2−0.8+2.6pb.

Published
1999

41. Multi-quasiparticle states in (256)Rf

Author

Jeppesen, H. B., Dragojevic, I., Clark, R. M., Gregorich, K. E., Ali, M. N., Allmond, J. M., Beausang, C. W., Bleuel, D. L., Cromaz, M., Deleplanque, M. A., Ellison, P. A., Fallon, P., Garcia, M. A., Gates, J. M., Greene, J. P., Gros, S., Lee, I. Y., Liu, H. L., Macchiavelli, A. O., Nelson, S. L., Nitsche, H., Pavan, J. R., Stavsetra, L., Stephens, F. S., Wiedeking, M., Wyss, Ramon, Xu, F. R., Jeppesen, H. B., Dragojevic, I., Clark, R. M., Gregorich, K. E., Ali, M. N., Allmond, J. M., Beausang, C. W., Bleuel, D. L., Cromaz, M., Deleplanque, M. A., Ellison, P. A., Fallon, P., Garcia, M. A., Gates, J. M., Greene, J. P., Gros, S., Lee, I. Y., Liu, H. L., Macchiavelli, A. O., Nelson, S. L., Nitsche, H., Pavan, J. R., Stavsetra, L., Stephens, F. S., Wiedeking, M., Wyss, Ramon, and Xu, F. R.

Abstract

Excited states in (256)Rf were populated via the Pb-208(Ti-50,2n) fusion-evaporation reaction. Delayed gamma-ray and electron decay spectroscopy was performed and three isomeric states in (256)Rf have been identified. A fourth low-energy nonyrast state was identified from the gamma-ray decay of one of the higher lying isomers. The states are interpreted as multi-quasiparticle excitations., QC 20100525

Published
2009
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42. LETTER TO THE EDITOR: Close doublet structures in , and neighbours: rotation-alignment for the half-filled subshell?

Author

University of Michigan, Ann Arbor, MI 48104, USA, Physics Department, Vanderbilt University, Nashville, TN 37235, USA, Physics Department, Vanderbilt University, Nashville, TN 37235, USA; Joint Institute for Nuclear Research, Dubna 141980, Russia; Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee, TN 37835, USA, Joint Institute for Nuclear Research, Dubna 141980, Russia, Department of Physics, Mississippi State University, MS 39762, USA, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA, Idaho National Engineering Laboratory, Idaho Falls, ID 83415-2114, USA, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA, Nuclear Engineering Department, University of California, Berkeley, CA 94720, USA, University Federal do Rio de Janeiro, Rio de Janeiro, CP 68528, RG Brazil, Ann Arbor, Hwang, J. K., Ramayya, A. V., Hamilton, J. H., Peker, L. K., Kormicki, J., Babu, B. R. S., Ginter, T. N., Beyer, C. J., 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., Gilat, J., 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., Griffin, H. C., Donangelo, R., University of Michigan, Ann Arbor, MI 48104, USA, Physics Department, Vanderbilt University, Nashville, TN 37235, USA, Physics Department, Vanderbilt University, Nashville, TN 37235, USA; Joint Institute for Nuclear Research, Dubna 141980, Russia; Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee, TN 37835, USA, Joint Institute for Nuclear Research, Dubna 141980, Russia, Department of Physics, Mississippi State University, MS 39762, USA, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA, Idaho National Engineering Laboratory, Idaho Falls, ID 83415-2114, USA, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA, Nuclear Engineering Department, University of California, Berkeley, CA 94720, USA, University Federal do Rio de Janeiro, Rio de Janeiro, CP 68528, RG Brazil, Ann Arbor, Hwang, J. K., Ramayya, A. V., Hamilton, J. H., Peker, L. K., Kormicki, J., Babu, B. R. S., Ginter, T. N., Beyer, C. J., 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., Gilat, J., 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., Griffin, H. C., and Donangelo, R.

Abstract

Several new transitions are assigned to and in a coincidence study from the spontaneous fission of with 72 Compton suppressed Ge detectors in Gammasphere. A close doublet structure of an odd-parity band except near its bandhead is a common feature not only of the nuclei studied here but of many others with . This doublet structure may be a general consequence of rotation alignment for configurations of half-filled j-shells, which are only weakly coupled to the deformed shapes.

Published
2006

43. Nuclear spectroscopy of the heaviest elements: studies of254No,257Rf, and261Sg

Author

Berryman, J S, primary, Clark, R M, additional, Gregorich, K E, additional, Allmond, J M, additional, Bleuel, D L, additional, Cooper, R J, additional, Cromaz, M, additional, Deleplanque, M A, additional, Dragojević, I, additional, Dvorak, J, additional, Ellison, P A, additional, Fallon, P, additional, Garcia, M A, additional, Gates, J M, additional, Gros, S, additional, Gothe, O, additional, Jeppesen, H B, additional, Kaji, D, additional, Lee, I Y, additional, Macchiavelli, A O, additional, Morimoto, K, additional, Nitsche, H, additional, Paschalis, S, additional, Petri, M, additional, Stavsetra, L, additional, Stephens, F S, additional, Stoyer, M A, additional, Ross, T J, additional, Watanabe, H, additional, and Wiedeking, M, additional

Published
2011
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44. Evidence for the synthesis of element $^{267}$110 produced by the $^{59}$Co + $^{209}$Bi reaction

Author

Ghiorso, A, Lee, D, Somerville, L P, Loveland, W, Nitschke, J M, Ghiorso, W, Seaborg, G T, Wilmarth, P A, Leres, R, Wydler, A, Nurmia, M J, Gregorich, K E, Gaylord, R, Hamilton, T, Hannink, N J, Hoffman, D C, Jarzynski, C, Kacher, C D, Kadkhodayan, B, Kreek, S A, Lane, M, Lyon, A L, McMahan, M A, Neu, M P, Sikkeland, T, Swiatecki, W J, Türler, A, Walton, J T, and Yashita, S

Subjects
Nuclear Physics
Published
1994

47. Decay properties of 256Sg(Z=106) and 266Sg(Z=106)

Author

Türler, A., Dressler, R., Eichler, B., Gäggeler, H. W., Jost, D. T., Schädel, M., Brüchle, W., Gregorich, K. E., Trautmann, N., Taut, S., Türler, A., Dressler, R., Eichler, B., Gäggeler, H. W., Jost, D. T., Schädel, M., Brüchle, W., Gregorich, K. E., Trautmann, N., and Taut, S.

Published
1998

48. Identification of neutron h11/2bands in121,123Cd

Author

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

Published
2002
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49. SISAK Liquid-Liquid Extraction Experiments with Preseparated 257Rf

Author

Omtvedt, Jon Petter, primary, Alstad, J., additional, Breivik, H., additional, Dyve, J. E., additional, Eberhardt, K., additional, FoldenIII, C. M., additional, Ginter, T., additional, Gregorich, K. E., additional, Hult, E. A., additional, Johansson, M., additional, Kirbach, U. W., additional, Lee, D. M., additional, Mendel, M., additional, N^|^auml;hler, A., additional, Ninov, V., additional, Omtvedt, L. A., additional, Patin, J. B., additional, Skarnemark, G., additional, Stavsetra, L., additional, Sudowe, R., additional, Wiehl, N., additional, Wierczinski, B., additional, Wilk, P. A., additional, Zielinski, P. M., additional, Kratz, J. V., additional, Trautmann, N., additional, Nitsche, H., additional, and Hoffman, D. C., additional

Published
2002
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