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Journal Articles

On the adsorption and reactivity of element 114, flerovium

Yakushev, A.*; Lens, L.*; D$"u$llmann, Ch. E.*; Khuyagbaatar, J.*; J$"a$ger, E.*; Krier, J.*; Runke, J.*; Albers, H. M.*; Asai, Masato; Block, M.*; et al.

Frontiers in Chemistry (Internet), 10, p.976635_1 - 976635_11, 2022/08

 Times Cited Count:11 Percentile:81.01(Chemistry, Multidisciplinary)

Flerovium (Fl, element 114) is the heaviest element chemically studied so far. The first chemical experiment on Fl suggested that Fl is a noble-gas-like element, while the second studies suggested that Fl has a volatile-metal-like character. To obtain more reliable conclusion, we performed further experimental studies on Fl adsorption behavior on Si oxide and gold surfaces. The present results suggest that Fl is highly volatile and less reactive than the volatile metal, Hg, but has higher reactivity than the noble gas, Rn.

Journal Articles

Search for elements 119 and 120

Khuyagbaatar, J.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Asai, Masato; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.

Physical Review C, 102(6), p.064602_1 - 064602_9, 2020/12

 Times Cited Count:45 Percentile:98.21(Physics, Nuclear)

A search for production of the superheavy elements with atomic numbers 119 and 120 was performed in the $$^{50}$$Ti+$$^{249}$$Bk and $$^{50}$$Ti+$$^{249}$$Cf fusion-evaporation reactions, respectively, at the gas-filled recoil separator TASCA. Over four months of irradiation, neither was detected at cross-section sensitivity levels of 65 and 200 fb, respectively. The non-observation 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.

Journal Articles

Fusion reaction $$^{48}$$Ca+$$^{249}$$Bk leading to formation of the element Ts (Z=117)

Khuyagbaatar, J.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Asai, Masato; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.

Physical Review C, 99(5), p.054306_1 - 054306_16, 2019/05

AA2019-0039.pdf:5.03MB

 Times Cited Count:24 Percentile:90.97(Physics, Nuclear)

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.

Journal Articles

Online chemical adsorption studies of Hg, Tl, and Pb on SiO$$_{2}$$ and Au surfaces in preparation for chemical investigations on Cn, Nh, and Fl at TASCA

Lens, L.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Asai, Masato; Ballof, J.*; Block, M.*; David, H. M.*; Despotopulos, J.*; Di Nitto, A.*; Eberhardt, K.*; et al.

Radiochimica Acta, 106(12), p.949 - 962, 2018/12

AA2018-0417.pdf:0.99MB

 Times Cited Count:8 Percentile:61.87(Chemistry, Inorganic & Nuclear)

Online gas-solid adsorption studies with single atom quantities of Hg, Tl, and Pb on SiO$$_{2}$$ and Au surfaces were carried out using short-lived radioisotopes with half-lives in the range of 4-49 s. This is a model study to measure adsorption enthalpies of superheavy elements Cn, Nh, and Fl. The short-lived isotopes were produced and separated by the gas-filled recoil separator TASCA at GSI. The products were stopped in He gas, and flushed into gas chromatography columns made of Si detectors whose surfaces were covered by SiO$$_{2}$$ or Au. The short-lived Tl and Pb were successfully measured by the Si detectors with the SiO$$_{2}$$ surface at room temperature. On the other hand, the Hg did not adsorb on the SiO$$_{2}$$ surface, but adsorbed on the Au surface. The results demonstrated that the adsorption properties of short-lived Hg, Tl, and Pb could be studied with this setup, and that this method is applicable to the experiment for Cn, Nh, and Fl.

Journal Articles

Radiochemical study of the kinematics of multi-nucleon transfer reactions in $$^{48}$$Ca + $$^{248}$$Cm collisions 10% above the Coulomb barrier

G$"o$tz, M.*; G$"o$tz, S.*; Kratz, J. V.*; D$"u$llmann, Ch. E.*; Mokry, Ch.*; Runke, J.*; Th$"o$rle-Pospiech, P.*; Wiehl, N.*; Sch$"a$del, M.; Ballof, J.*; et al.

Nuclear Physics A, 961, p.1 - 21, 2017/05

 Times Cited Count:6 Percentile:46.42(Physics, Nuclear)

The kinematics of multi-nucleon transfer reactions in the $$^{48}$$Ca + $$^{248}$$Cm collisions were investigated using a stacked-foil technique and radiochemical separations. In previous studies, isotopic distributions of the products of below-target isotopes were found to be broader than those of above-target isotopes, which had been interpreted as larger contributions of strongly dumped collisions in the productions of below-target isotopes than above-target ones. However, in the present study, the average total kinetic energy loss (TKEL), and thus, the average excitation energies were determined for both below-target and above-target isotopes, and they were found to be similar. This contradicts the previous interpretation, and thus, a new interpretation has been proposed; highly excited above-target products are lost by fission.

Journal Articles

Recoil-$$alpha$$-fission and recoil-$$alpha$$-$$alpha$$-fission events observed in the reaction $$^{48}$$Ca + $$^{243}$$Am

Forsberg, U.*; Rudolph, D.*; Andersson, L.-L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Fahlander, C.*; Gates, J. M.*; Golubev, P.*; Gregorich, K. E.*; Gross, C. J.*; et al.

Nuclear Physics A, 953, p.117 - 138, 2016/09

 Times Cited Count:46 Percentile:94.21(Physics, Nuclear)

Alpha-decay chains observed in the element-115 production reactions of $$^{48}$$Ca + $$^{243}$$Am were investigated using a new data set consisting of our recently reported data obtained at GSI and previously reported ones at Dubna and LBNL. Short decay chains of recoil-$$alpha$$-($$alpha$$)-fission type, fourteen of which were observed, and some of which were interpreted as the 2-neutron evaporation products $$^{289}$$Mc, have been reassigned. It is plausible that most of them were assigned to the 3-neutron evaporation products $$^{288}$$Mc whose decay chain would on the way have branches of EC decays followed by fission.

Journal Articles

Selected spectroscopic results on element 115 decay chains

Rudolph, D.*; Forsberg, U.*; Golubev, P.*; Sarmiento, L. G.*; Yakushev, A.*; Andersson, L.-L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Gates, J. M.*; Gregorich, K. E.*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 303(2), p.1185 - 1190, 2015/02

 Times Cited Count:7 Percentile:50.83(Chemistry, Analytical)

Thirty correlated $$alpha$$-decay chains of element 115 were observed, which were consistent with previous observations interpreted as the decay chain of $$^{288}$$115. GEANT4 Monte-Carlo simulations were performed to reproduce high-resolution $$alpha$$-photon coincidence results, which allows one to propose Q$$_{alpha}$$ values and excitation schemes of the superheavy nuclei with unprecedented precision.

Journal Articles

$$^{48}$$Ca + $$^{249}$$Bk fusion reaction leading to element Z = 117; Long-lived $$alpha$$-decaying $$^{270}$$Db and discovery of $$^{266}$$Lr

Khuyagbaatar, J.*; Yakushev, A.*; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Asai, Masato; Block, M.*; Boll, R. A.*; Brand, H.*; Cox, D. M.*; et al.

Physical Review Letters, 112(17), p.172501_1 - 172501_5, 2014/05

 Times Cited Count:210 Percentile:98.42(Physics, Multidisciplinary)

The superheavy element with atomic number 117 was produced in the $$^{48}$$Ca + $$^{249}$$Bk fusion reaction using the gas-filled recoil separator TASCA at GSI in Germany. This result verified the previous result of the discovery of new element 117 reported by Flerov Laboratory of Nuclear Reactions in Russia, which makes certain the synthesis and discovery of element 117 in human history. On the other hand, the last nucleus in the $$alpha$$ decay chain from the element 117 was assigned to be the unknown nucleus $$^{266}$$Lr instead of the previously reported $$^{270}$$Db, and $$^{270}$$Db was found to be the $$alpha$$-decaying nucleus with very long half-life.

Journal Articles

Spectroscopic tools applied to element Z = 115 decay chains

Forsberg, U.*; Rudolph, D.*; Golubev, P.*; Sarmiento, L. G.*; Yakushev, A.*; Andersson, L.-L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Gates, J. M.*; Gregorich, K. E.*; et al.

EPJ Web of Conferences, 66, p.02036_1 - 02036_4, 2014/03

 Times Cited Count:7 Percentile:88.63(Physics, Nuclear)

A focal-plane Si detector setup applied to the spectroscopy of the element 115 $$alpha$$-decay chains was reported. Results of the digital signal analysis for preamplifier signals and of the event-by-event $$alpha$$-energy loss correction analysis were presented. The detectors consist of five double-sided Si strip detectors (DSSSD) arranged as a box, and signals from one side of the detector at the bottom of the box were digitally processed. Energy losses of $$alpha$$ particles detected by two Si detectors at the bottom and a side differs event-by-event, because each $$alpha$$ particle passed through two dead layers with a certain tilted angle. By correcting for the energy loss of each $$alpha$$ event using the angle of the $$alpha$$-particle emission extracted from the detected positions, we succeeded in improving the $$alpha$$ energy resolution significantly.

Journal Articles

Alpha-photon coincidence spectroscopy along element 115 decay chains

Rudolph, D.*; Forsberg, U.*; Golubev, P.*; Sarmiento, L. G.*; Yakushev, A.*; Andersson, L.-L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Gates, J. M.*; Gregorich, K. E.*; et al.

Acta Physica Polonica B, 45(2), p.263 - 272, 2014/02

 Times Cited Count:22 Percentile:75.00(Physics, Multidisciplinary)

Produced in the reaction of $$^{48}$$Ca beam with an $$^{243}$$Am target, thirty correlated $$alpha$$-decay chains were observed. Observed decay chains are consistent with a previously reported decay chain, which confirms the identification of the element 115. In addition, an $$alpha$$-photon coincidence measurement was performed, and $$gamma$$ rays as well as X-ray candidates were observed in this decay chain. The $$gamma$$-ray observation in the heaviest region of superheavy nuclei brings a big progress in the superheavy nuclear structure studies.

Journal Articles

Superheavy element flerovium (element 114) is a volatile metal

Yakushev, A.*; Gates, J. M.*; T$"u$rler, A.*; Sch$"a$del, M.; D$"u$llmann, Ch. E.*; Ackermann, D.*; Andersson, L.-L.*; Block, M.*; Br$"u$chle, W.*; Dvorak, J.*; et al.

Inorganic Chemistry, 53(3), p.1624 - 1629, 2014/02

 Times Cited Count:105 Percentile:98.87(Chemistry, Inorganic & Nuclear)

We report on a gas-solid chromatography study of the adsorption of element 114 (flerovium, Fl) on a Au surface. Fl was produced in the nuclear fusion reaction $$^{244}$$Pu($$^{48}$$Ca, 3-4n)$$^{288,289}$$Fl and was isolated in-flight from the primary $$^{48}$$ beam in a physical recoil separator. The adsorption behavior of Fl, its nuclear $$alpha$$-decay product Cn, their lighter homologues in groups 14 and 12, i.e., Pb and Hg, and the noble gas Rn were studied simultaneously by isothermal gas chromatography and thermochromatography. Two Fl atoms were detected. They adsorbed on a Au surface at room temperature, but not as readily as Pb and Hg. The observed adsorption behavior of Fl points to a higher inertness compared to its nearest homologue in the group, Pb. However, the measured lower limit for the adsorption enthalpy of Fl on a Au surface points to the formation of a metal-metal bond of Fl with Au. Fl is the least reactive element in the group, but still a metal.

Journal Articles

Spectroscopy of element 115 decay chains

Rudolph, D.*; Forsberg, U.*; Golubev, P.*; Sarmiento, L. G.*; Yakushev, A.*; Andersson, L. L.*; Di Nitto, A.*; D$"u$llmann, Ch. E.*; Gates, J. M.*; Gregorich, K. E.*; et al.

Physical Review Letters, 111(11), p.112502_1 - 112502_5, 2013/09

 Times Cited Count:125 Percentile:96.18(Physics, Multidisciplinary)

Journal Articles

Rapid synthesis of radioactive transition-metal carbonyl complexes at ambient conditions

Even, J.*; Yakushev, A.*; D$"u$llmann, C. E.*; Dvorak, J.*; Eichler, R.*; Gothe, O.*; Hild, D.*; J$"a$ger, E.*; Khuyagbaatar, J.*; Kratz, J. V.*; et al.

Inorganic Chemistry, 51(12), p.6431 - 6433, 2012/06

 Times Cited Count:36 Percentile:83.21(Chemistry, Inorganic & Nuclear)

Carbonyl complexes of radioactive transition metals can be easily synthesized with high yields by stopping nuclear fission or fusion products in a gas volume containing CO. Here, we focus on Mo, W, and Os complexes. The reaction takes place at pressures of around 1 bar at room temperature, i.e., at conditions that are easy to accommodate. The formed complexes are highly volatile. They can thus be transported within a gas stream without major losses to setups for their further investigation or direct use. The rapid synthesis holds promise for radiochemical purposes and will be useful for studying, e.g., chemical properties of superheavy elements.

Journal Articles

The Recoil transfer chamber; An Interface to connect the physical preseparator TASCA with chemistry and counting setups

Even, J.*; Ballof, J.*; Br$"u$chle, W.*; Buda, R. A.*; D$"u$llmann, Ch. E.*; Eberhardt, K.*; Gorshkov, A.*; Gromm, E.*; Hild, D.*; J$"a$ger, E.*; et al.

Nuclear Instruments and Methods in Physics Research A, 638(1), p.157 - 164, 2011/03

 Times Cited Count:24 Percentile:85.45(Instruments & Instrumentation)

Journal Articles

Experimental study of the $$^{238}$$U($$^{36}$$S, 3-5$$n$$)$$^{269-271}$$Hs reaction leading to the observation of $$^{270}$$Hs

Graeger, R.*; Ackermann, D.*; Chelnokov, M.*; Chepigin, V.*; D$"u$llmann, C. E.*; Dvorak, J.*; Even, J.*; Gorshkov, A.*; He${ss}$berger, F. P.*; Hild, D.*; et al.

Physical Review C, 81(6), p.061601_1 - 061601_5, 2010/06

 Times Cited Count:43 Percentile:89.80(Physics, Nuclear)

Journal Articles

Cross section limits for the $$^{248}$$Cm($$^{25}$$Mg, 4$$n$$-5$$n$$)$$^{268,269}$$Hs reactions

Dvorak, J.*; Br$"u$chle, W.*; D$"u$llmann, Ch. E.*; Dvorakova, Z.*; Eberhardt, K.*; Eichler, R.*; J$"a$ger, E.*; Nagame, Yuichiro; Qin, Z.*; Sch$"a$del, M.*; et al.

Physical Review C, 79(3), p.037602_1 - 037602_4, 2009/05

 Times Cited Count:17 Percentile:69.83(Physics, Nuclear)

no abstracts in English

Journal Articles

Observation of the 3$$n$$ evaporation channel in the complete hot-fusion reaction $$^{26}$$Mg + $$^{248}$$Cm leading to the new superheavy nuclide $$^{271}$$Hs

Dvorak, J.*; Br$"u$chle, W.*; Chelnokov, M.*; D$"u$llmann, Ch. E.*; Dvorakova, Z.*; Eberhardt, K.*; J$"a$ger, E.*; Kr$"u$cken, R.*; Kuznetsov, A.*; Nagame, Yuichiro; et al.

Physical Review Letters, 100(13), p.132503_1 - 132503_4, 2008/04

The analysis of a large body of heavy ion fusion reaction data with medium-heavy projectiles (6$$leq$$Z$$leq$$18) and actinide targets suggests a disappearance of the 3$$n$$ exit channel with increasing atomic number of the projectile. Here, we report a measurement of the excitation function of the reaction $$^{248}$$Cm($$^{26}$$Mg,$$xn$$)$$^{274-x}$$Hs and the observation of the new nuclide $$^{271}$$Hs produced in the 3$$n$$ evaporation channel at a beam energy well below the Bass fusion barrier with a cross section comparable to the maxima of the 4$$n$$ and 5$$n$$ channels. This indicates the possible discovery of new neutron-rich transactinide nuclei using relatively light heavy ion beams of the most neutron-rich stable isotopes and actinide targets.

Journal Articles

Observation of the 3$$n$$ evaporation channel in the complete hot-fusion reaction $$^{26}$$Mg+$$^{248}$$Cm leading to the new superheavy nuclide $$^{271}$$Hs

Dvorak, J.*; Br$"u$chle, W.*; Chelnokov, M.*; D$"u$llmann, Ch. E.*; Dvorakova, Z.*; Eberhardt, K.*; J$"a$ger, E.*; Kr$"u$cken, R.*; Kuznetsov, A.*; Nagame, Yuichiro; et al.

Physical Review Letters, 100(13), p.132503_1 - 132503_4, 2008/04

 Times Cited Count:125 Percentile:94.89(Physics, Multidisciplinary)

Journal Articles

Doubly magic nucleus $$^{270}_{108}$$Hs$$_{162}$$

Dvorak, J.*; Br$"u$chle, W.*; Chelnokov, M.*; Dressler, R.*; D$"u$llmann, Ch. E.*; Eberhardt, K.*; Gorshkov, V.*; J$"a$ger, E.*; Kr$"u$cken, R.*; Kuznetsov, A.*; et al.

Physical Review Letters, 97(24), p.242501_1 - 242501_4, 2006/12

 Times Cited Count:152 Percentile:96.00(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Fluoride complexation of rutherfordium (Rf, element 104)

Strub, E.*; Br$"u$chle, W.*; Eichler, R.*; G$"a$ggeler, H. W.*; Glatz, J. P.*; Grund, A.*; G$"a$rtner, M.*; J$"a$ger, E.*; Jost, D.*; Kirbach, U.*; et al.

1st International Conference on the Chemistry and Physics of the Transactinide Elements; Extended Abstracts, 4 Pages, 1999/00

no abstracts in English

Journal Articles

Chromatographic studies of rutherfordium (element 104) with tributylphosphate

Br$"u$chle, W.*; Eichler, B.*; G$"a$ggeler, H. W.*; Guenther, R.*; J$"a$ger, E.*; Jost, D.*; Kratz, J. V.*; Nagame, Yuichiro; Paulus, W.*; Pershina, V.*; et al.

Proceedings of 1st International Conference on the Chemistry and Physics of the Transactinide Elements, 3 Pages, 1999/00

no abstracts in English

21 (Records 1-20 displayed on this page)