34 results on '"Birgit Kindler"'
Search Results
2. Spontaneous fission instability of the neutron-deficient No and Rf isotopes: The new isotope No249
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Ch. E. Düllmann, F. P. Heßberger, Egon Jäger, Bettina Lommel, Alexander Yakushev, Birgit Kindler, J. Krier, B. Schausten, H. Brand, R. A. Cantemir, N. Kurz, and J. Khuyagbaatar
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Physics ,Isotope ,Atomic orbital ,Fission ,Atomic nucleus ,Electron shell ,Neutron ,Atomic physics ,Nuclear Experiment ,Spontaneous fission ,Line (formation) - Abstract
In the heaviest elements, the instability of atomic nuclei against spontaneous fission leads to ever shorter nuclear half-lives. Upon falling below a timescale of ${10}^{\ensuremath{-}14}$ s, the border of existence of isotopes is crossed because this is the timescale on which the formation of atomic shells occurs. Analysis of the experimental data on the spontaneous fission half-lives of Rf isotopes in relation with their expected single-particle orbitals hint at a potentially abrupt decrease in half-lives of unknown neutron-deficient Rf isotopes with neutron numbers $l149$, which suggests that the isotopic border is already almost reached. However, this conjecture, which cannot be explained within the current knowledge, was directly related to uncertainty in the experimental data on $^{253}\mathrm{Rf}$. We revisited the decay of $^{253}\mathrm{Rf}$ and identified two fission activities, which are attributed to decays of the two different states with half-lives of $12.{8}_{\ensuremath{-}3.4}^{+7.0}$ ms and ${44}_{\ensuremath{-}10}^{+17}\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{s}$. In addition, hitherto unknown $\ensuremath{\alpha}$ decay in $^{253}\mathrm{Rf}$, which is followed by $\ensuremath{\alpha}$ decay of the new isotope $^{249}\mathrm{No}$ with a half-life of ${15}_{\ensuremath{-}7}^{+74}$ ms, was observed. Based on our new data, no abrupt decreases in half-lives of the neutron-deficient No and Rf isotopes are expected, which is in line with theoretical predictions. Fission half-lives of the two different states in $^{253}\mathrm{Rf}$ are benchmark cases for the theoretical description of the single-particle orbital influence on the fission process.
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- 2021
3. Isomeric states in Rf256
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J. Krier, Birgit Kindler, S. Götz, Alexander Yakushev, Egon Jäger, J. Khuyagbaatar, B. Schausten, Bettina Lommel, H. Brand, Ch. E. Düllmann, F. P. Heßberger, R. A. Cantemir, N. Kurz, and M. Götz
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Physics ,Good quantum number ,education.field_of_study ,Population ,Transactinide element ,Production (computer science) ,Electron ,Atomic physics ,education ,Recoil separator - Abstract
The question of the number and origin of isomeric states in $^{256}\mathrm{Rf}$ arose from two independent experiments but remained unanswered for a decade. To shed light on this puzzle, we studied isomeric decay in $^{256}\mathrm{Rf}$ by measuring conversion electrons with fast fully digital electronics. $^{256}\mathrm{Rf}$ was produced in the fusion-evaporation reactions of $^{50}\mathrm{Ti}+^{207}\mathrm{Pb}$ and $^{50}\mathrm{Ti}+^{208}\mathrm{Pb}$ at the gas-filled recoil separator TransActinide Separator and Chemistry Apparatus. Among a total of 120 decays of $^{256}\mathrm{Rf}$, we detected 22 and 12 decays proceeding through one and two isomeric states. Half-lives of the low- and higher-lying states were assigned to be ${T}_{1/2}={14}_{\ensuremath{-}4}^{+6}$ and ${10}_{\ensuremath{-}3}^{+5}\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{s}$, respectively. Population rates of these isomeric states were estimated to be $\ensuremath{\approx}18%$ and $g10%$, which are similar to those for two-quasiparticle $K$ isomeric states in this region of nuclei. The results, thus, confirm an earlier claim on the existence of multiple $K$ isomeric states in $^{256}\mathrm{Rf}$ and show their population rates are as high as in No isotopes. Suggestively, $K$ remains a good quantum number in isotopes of heavier elements like Sg and Hs, where yet unknown high-$K$ isomeric states still could exist. The present experimental results demonstrate that the ``triggerless'' measurement guarantees an efficient detection of delayed conversion electron signals. Thus, it is a very efficient method for the identification of isomeric states in experiments with one nucleus-at-a-time production rates.
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- 2021
4. Search for elements 119 and 120
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Michael Block, Mahananda Dasgupta, S. Minami, Susanta Lahiri, M. Wegrzecki, N. Kurz, Rose A. Boll, Andreas Türler, J. V. Kratz, R-D Herzberg, Daniel Cox, James B. Roberto, Claes Fahlander, Jadambaa Khuyagbaatar, Dirk Rudolph, K. P. Rykaczewski, A. Hübner, G. K. Pang, K. Miernik, N. Gharibyan, B. Schausten, J. Hoffmann, L.-L. Andersson, Bettina Lommel, Luis Sarmiento, U. Forsberg, Matthias Schädel, J. H. Hamilton, Juha Uusitalo, Kenneth E. Gregorich, Heino Nitsche, H. Brand, Julia Even, Moumita Maiti, J. M. Gates, David Hinde, Philippos Papadakis, M. Laatiaoui, Norbert Wiehl, Klaus Eberhardt, W. Hartmann, J. Runke, D. A. Shaughnessy, Dieter Ackermann, Petra Thörle-Pospiech, K. Tinschert, R. Lang, C. Mokry, Birgit Kindler, Jon Petter Omtvedt, Ch. E. Düllmann, S. M. Van Cleve, J. Steiner, D. Renisch, A. K. Mistry, M. Asai, Maurits Evers, Alexander Yakushev, Patrick Steinegger, A. Semchenkov, Pavel Golubev, V. Yakusheva, X. Derkx, Evgeny E. Tereshatov, J. Krier, Norbert Trautmann, T. Torres De Heidenreich, A. Di Nitto, F. P. Heßberger, R. Hollinger, Egon Jäger, 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, 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., Wegrzecki, M., Wiehl, N., Van Cleve, S. M., Yakusheva, V., and Van Swinderen Institute for Particle Physics and G
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Physics ,element 119 ,010308 nuclear & particles physics ,element 120 ,Superheavy Elements ,01 natural sciences ,Island of stability ,Recoil separator ,Nuclear physics ,superheavy elements ,Production cross section ,Subatomic Physics ,0103 physical sciences ,540 Chemistry ,570 Life sciences ,biology ,low and intermediate energy heavy-ion reactions ,Atomic number ,Irradiation ,Sensitivity (control systems) ,ydinfysiikka ,010306 general physics ,Beam energy - 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. peerReviewed
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- 2020
5. α decay of Fm243143 and Fm245145 , and of their daughter nuclei
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Birgit Kindler, Stefan G. Hofmann, Katsuhisa Nishio, Dieter Ackermann, J. Khuyagbaatar, S. Heinz, R. Mann, H. G. Burkhard, F. P. Heßberger, J. Maurer, I. Kojouharov, and Bettina Lommel
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Physics ,010308 nuclear & particles physics ,0103 physical sciences ,Nuclear structure ,Alpha decay ,Atomic physics ,Nuclear Experiment ,010306 general physics ,01 natural sciences ,Spontaneous fission - Abstract
Nuclear structure of $^{243}\mathrm{Fm}$, $^{245}\mathrm{Fm}$, and their daughter nuclei were investigated via detection of their radioactive decays, $\ensuremath{\alpha}$, $\ensuremath{\gamma}$, and spontaneous fission. Measured $\ensuremath{\alpha}$-decay energies, half-lives, and branching ratios improve the literature data significantly. A signature for detection of the hitherto unknown $^{235}\mathrm{Cm}$ was found in the $\ensuremath{\alpha}$-decay chains from $^{243}\mathrm{Fm}$. Two groups of $\ensuremath{\alpha}$ events with average energies of 6.69(2) MeV and 7.01(2) MeV and with a half-life of ${T}_{1/2}={300}_{\ensuremath{-}100}^{+250}$ s are suggested to originate from $^{235}\mathrm{Cm}$. Tentative decay schemes for $^{243}\mathrm{Fm}$, $^{239}\mathrm{Cf}$, $^{235}\mathrm{Cm}$, and $^{245}\mathrm{Fm}$, $^{241}\mathrm{Cf}$ isotopes are suggested based on the present experimental data. Systematical trends of single-particle states in $N=141$ isotones of $Z=92--98$ nuclei are discussed.
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- 2020
6. Systematic evidence for quasifission in Be9−, C12−, and O16 -induced reactions forming No258,260
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Mahananda Dasgupta, L. T. Bezzina, Petra Thörle-Pospiech, Annette Berriman, Jörg Runke, T. Banerjee, Edward Simpson, H. M. Albers, Ch. E. Düllmann, Bettina Lommel, K. Banerjee, Norbert Trautmann, C. Sengupta, C. Mokry, T. Tanaka, David Hinde, Alexander Yakushev, J. Khuyagbaatar, Klaus Eberhardt, Birgit Kindler, B. M. A. Swinton-Bland, and D. Y. Jeung
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Physics ,010308 nuclear & particles physics ,0103 physical sciences ,Physical chemistry ,010306 general physics ,01 natural sciences - Published
- 2020
7. K isomerism in Rf255 and total kinetic energy measurements for spontaneous fission of Rf255,256,258
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Michael Block, P. Mosat, Z. Kalaninová, M. Laatiaoui, Bettina Lommel, Sigurd Hofmann, M. Vostinar, J. Piot, B. Andel, A. K. Mistry, S. Antalic, Birgit Kindler, Dieter Ackermann, and F. P. Heßberger
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Physics ,010308 nuclear & particles physics ,Fission ,chemistry.chemical_element ,Kinetic energy ,01 natural sciences ,chemistry ,Metastability ,0103 physical sciences ,Rutherfordium ,Energy deficit ,Atomic physics ,010306 general physics ,Excitation ,Spontaneous fission - Abstract
Spontaneous fission properties of the isotopes $^{255}\mathrm{Rf}$, $^{256}\mathrm{Rf}$, and $^{258}\mathrm{Rf}$ produced in the reactions $^{50}\mathrm{Ti}+^{207}\mathrm{Pb}$, $^{50}\mathrm{Ti}+^{208}\mathrm{Pb}$, and $^{50}\mathrm{Ti}+^{209}\mathrm{Bi}$ were studied. The method of time and position correlations was used to identify spontaneous fission events. The correction to the energy deficit in measured total kinetic energy (TKE) determined on the basis of a study of $^{252}\mathrm{No}$ was applied to evaluate the $\overline{\mathrm{TKE}}$ of investigated rutherfordium isotopes. A signature which we assigned tentatively to bimodal fission was observed in TKE distributions of $^{255}\mathrm{Rf}$ and $^{256}\mathrm{Rf}$. Two new high-K isomeric states in $^{255}\mathrm{Rf}$ were identified by ER-CE-(CE)-$\ensuremath{\alpha}$/SF correlation search, with half-lives of ${38}_{\ensuremath{-}7}^{+12}$ and ${15}_{\ensuremath{-}4}^{+6}$ $\ensuremath{\mu}\mathrm{s}$ at excitation energies 1150--1450 and 900--1200 keV, respectively. Including those metastable states a tentative partial level scheme was proposed.
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- 2020
8. Fusion reaction Ca48+Bk249 leading to formation of the element Ts ( Z=117 )
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Rose A. Boll, G. K. Pang, Daniel Cox, Susanta Lahiri, F. P. Heßberger, J. Hoffmann, Daniel Ward, Evgeny E. Tereshatov, M. Wegrzecki, K. Tinschert, R. Lang, Andreas Türler, J. Krier, Claes Fahlander, C. Mokry, Julia Even, T. Torres De Heidenreich, Egon Jäger, D. Renisch, J. V. Kratz, D. A. Shaughnessy, H. Brand, R. Hollinger, J. M. Gates, Jon Petter Omtvedt, X. Derkx, S. M. Van Cleve, L.-L. Andersson, Philippos Papadakis, S. Minami, Klaus Eberhardt, U. Forsberg, W. Hartmann, A. Di Nitto, Norbert Trautmann, James B. Roberto, N. Kurz, V. Yakusheva, J. Runke, Bettina Lommel, Mahananda Dasgupta, A. Hübner, Alexander Yakushev, Matthias Schädel, Kenneth E. Gregorich, Patrick Steinegger, B. Schausten, H. Nitsche, Birgit Kindler, Luis Sarmiento, Juha Uusitalo, Maurits Evers, Dirk Rudolph, K. Miernik, R.-D. Herzberg, Ch. E. Düllmann, N. Gharibyan, A. Semchenkov, Pavel Golubev, Dieter Ackermann, Petra Thörle-Pospiech, J. Steiner, A. K. Mistry, M. Asai, David Hinde, Michael Block, M. Laatiaoui, Norbert Wiehl, K. P. Rykaczewski, J. H. Hamilton, Jadambaa Khuyagbaatar, and Moumita Maiti
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Physics ,Nuclear physics ,Nuclear Theory ,Nuclear fusion ,Decay chain ,Alpha decay ,Actinide ,Superheavy Elements ,Nuclear Experiment ,Recoil separator - 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.
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- 2019
9. Low-lying states in Ra219 and Rn215 : Sampling microsecond α -decaying nuclei
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Alexander Yakushev, Ingemar Ragnarsson, N. Kurz, Julia Even, K. P. Rykaczewski, T. Torres, Carl J Gross, I. Kojouharov, Andreas Türler, R.-D. Herzberg, Dirk Rudolph, J. P. Omtvedt, Jörg Runke, B. Schausten, Luis Sarmiento, J. Krier, F. P. Heßberger, Pavel Golubev, Ch. E. Düllmann, J. M. Gates, Birgit Kindler, L.-L. Andersson, Michael Block, J. V. Kratz, B. G. Carlsson, Norbert Wiehl, Bettina Lommel, Klaus Eberhardt, Dieter Ackermann, Petra Thörle-Pospiech, Norbert Trautmann, Egon Jäger, H. Schaffner, Claes Fahlander, Kenneth E. Gregorich, J. Gerl, Matthias Schädel, A. Di Nitto, A. Ward, U. Forsberg, C. Mokry, J Ljungberg, A. Såmark-Roth, Philippos Papadakis, H. Brand, A. K. Mistry, Jadambaa Khuyagbaatar, and Daniel Cox
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Physics ,010308 nuclear & particles physics ,Nuclear shell model ,Half-life ,01 natural sciences ,Nuclear physics ,Microsecond ,0103 physical sciences ,Atomic nucleus ,Gamma spectroscopy ,Alpha decay ,Decay chain ,Nuclide ,010306 general physics - 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. (Less)
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- 2018
10. Nuclear structure dependence of fusion hindrance in heavy element synthesis
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Aditya Wakhle, J. Walshe, J. Khuyagbaatar, Bettina Lommel, K. Vo-Phuoc, Duc Huy Luong, Alexander Yakushev, E.V. Prasad, Cedric Simenel, Edward Simpson, Ian Carter, Mahananda Dasgupta, C. Sengupta, Ch. E. Düllmann, H. M. David, D. Y. Jeung, Elizabeth Williams, Birgit Kindler, J.F. Smith, D. C. Rafferty, Kaitlin Cook, and David Hinde
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Physics ,Fusion ,010308 nuclear & particles physics ,Fission ,Nuclear Theory ,Nuclear structure ,7. Clean energy ,01 natural sciences ,Nuclear physics ,0103 physical sciences ,Production (computer science) ,Heavy ion ,Heavy element ,Detector array ,Nuclear Experiment ,010306 general physics - Abstract
The production of the heaviest elements in fusion-evaporation reactions is substantially limited by very low cross sections, as fusion cross sections (including fusion-fission) are greatly reduced by the competing quasifission mechanism. Using the Australian National University Heavy Ion Accelerator Facility and CUBE detector array, fission fragments from the $^{48}\mathrm{Ti}+^{204,208}\mathrm{Pb}$ and $^{50}\mathrm{Ti}+^{206,208}\mathrm{Pb}$ reactions have been measured, with the aim to investigate how the competition between quasifission and fusion-fission evolves with small changes in entrance-channel properties associated mainly with the nuclear structure. Analysis of mass-distribution widths of strongly mass-angle-correlated fission fragments within the framework of the compound-nucleus fission theory demonstrates significant differences in quasifission (and therefore fusion) probabilities among the four reactions. The impact of nuclear structure on fusion highlights the importance of future radioactive beams.
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- 2018
11. Short-lived isomers inPo192andPo194
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Mark Huyse, Pasi Kuusiniemi, B. Andel, F. P. Heßberger, Z. Kalaninová, I. Kojouharov, Andrei Andreyev, Katsuhisa Nishio, Dieter Ackermann, Bettina Lommel, Birgit Kindler, B. Sulignano, Robert Page, P. Van Duppen, S. Antalic, and Sigurd Hofmann
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Physics ,Crystallography ,Nuclear magnetic resonance ,010308 nuclear & particles physics ,0103 physical sciences ,010306 general physics ,Spin (physics) ,01 natural sciences - Abstract
Isomeric states in $^{194}\mathrm{Po}$ and $^{192}\mathrm{Po}$ were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions $^{141}\mathrm{Pr}$($^{56}\mathrm{Fe}, \mathrm{p}2\mathrm{n})^{194}\mathrm{Po}$ and $^{144}\mathrm{Sm}$($^{51}\mathrm{V}, \mathrm{p}2\mathrm{n})^{192}\mathrm{Po}$. Several new $\ensuremath{\gamma}$-ray transitions were attributed to the isomers and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in $^{194}\mathrm{Po}$, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (${11}^{\ensuremath{-}}$) to (${10}^{\ensuremath{-}}$). The de-excitation of the (${11}^{\ensuremath{-}}$) isomeric level in $^{192}\mathrm{Po}$ by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV ($E3$) transition to (${8}^{+}$) level of the ground-state band was suggested. Moreover, side feeding to the (${4}^{+}$) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting ${11}^{\ensuremath{-}}$ isomers in neighboring Po and Pb isotopes.
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- 2016
12. Levels inTh223populated byαdecay ofU227
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J. Maurer, Bettina Lommel, Z. Kalaninová, F. P. Heßberger, B. Andel, M. Laatiaoui, Dieter Ackermann, S. Antalic, and Birgit Kindler
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Physics ,Nuclear and High Energy Physics ,Excited state ,Energy spectrum ,Atomic physics - Abstract
Levels in $^{223}\mathrm{Th}$ populated by the $\ensuremath{\alpha}$ decay of $^{227}\mathrm{U}$ were investigated using $\ensuremath{\alpha}\text{\ensuremath{-}}\ensuremath{\gamma}$ decay spectroscopy. The $^{227}\mathrm{U}$ isotope was produced in the fusion-evaporation reaction $^{22}\mathrm{Ne}+^{208}\mathrm{Pb}$ at the velocity filter separator for heavy-ion reaction products at Gesellschaft f\"ur Schwerionenforschung in Darmstadt (Germany). Several new excited levels and $\ensuremath{\gamma}$ transitions were identified in $^{223}\mathrm{Th}$. An improved $\ensuremath{\alpha}$-decay scheme of $^{227}\mathrm{U}$ was suggested. The experimental $\ensuremath{\alpha}$-decay energy spectrum of $^{227}\mathrm{U}$ was compared with the Monte Carlo simulation performed using the toolkit geant4.
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- 2015
13. Observation of mass-asymmetric fission of mercury nuclei in heavy ion fusion
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Elizabeth Williams, Aditya Wakhle, D. C. Rafferty, K. Ramachandran, Bettina Lommel, Cedric Simenel, S. D. McNeil, Ian Carter, Birgit Kindler, D. Y. Jeung, E.V. Prasad, C. S. Palshetkar, Kaitlin Cook, Duc Huy Luong, Mahananda Dasgupta, Ch. E. Düllmann, Jadambaa Khuyagbaatar, and David Hinde
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Physics ,Nuclear and High Energy Physics ,education.field_of_study ,Isotope ,Spectrometer ,Fission ,Nuclear Theory ,Population ,Mass ratio ,Saddle point ,Neutron ,Atomic physics ,Nuclear Experiment ,education ,Excitation - Abstract
Background: Mass-asymmetric fission has been observed in low energy fission of $^{180}\mathrm{Hg}$. Calculations predicted the persistence of asymmetric fission in this region even at excitation energies of 30--40 MeV.Purpose: To investigate fission mass distributions by populating different isotopes of Hg using heavy ion fusion reactions.Methods: Fission fragment mass-angle distributions have been measured for two reactions, $^{40}\mathrm{Ca}+^{142}\mathrm{Nd}$ and $^{13}\mathrm{C}+^{182}\mathrm{W}$, populating $^{182}\mathrm{Hg}$ and $^{195}\mathrm{Hg}$, respectively, using the Heavy Ion Accelerator Facility and CUBE spectrometer at the Australian National University. Measurements were made at beam energies around the capture barrier for the two reactions and mass ratio distributions were obtained using the kinematic reconstruction method.Results: Asymmetric fission has been observed following the population of $^{182}\mathrm{Hg}$ at an excitation energy of 22.8 MeV above the saddle point. A symmetric peaked mass ratio distribution was observed for $^{195}\mathrm{Hg}$ nuclei at a similar excitation energy above the saddle point.Conclusions: Mass-asymmetric fission has been observed in neutron deficient Hg nuclei populated via heavy ion fusion for the first time. The results are consistent with observations from beta-delayed fission measurements and provide a proof-of-principle for expanding experimental studies of the influence of shell effects on the fission processes.
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- 2015
14. αdecay ofAu176
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Birgit Kindler, Dieter Ackermann, F. P. Heßberger, R. Mann, Bettina Lommel, M. Venhart, J. Elseviers, Andrei Andreyev, P. Van Duppen, J. Khuyagbaatar, Marc Huyse, Sigurd Hofmann, R. D. Page, S. Heinz, S. Antalic, S. Franchoo, and Thomas Elias Cocolios
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Physics ,Nuclear and High Energy Physics ,Crystallography ,Branching fraction ,Excited state ,Nuclear Experiment - Abstract
The isotope $^{176}\mathrm{Au}$ has been studied in the complete fusion reaction $^{40}\mathrm{Ca}+^{141}\mathrm{Pr} \phantom{\rule{0.28em}{0ex}}\ensuremath{\rightarrow} {}^{176}\mathrm{Au}+5n$ at the velocity filter SHIP (GSI, Darmstadt). The complex fine-structure $\ensuremath{\alpha}$ decay of two isomeric states in $^{176}\mathrm{Au}$ feeding several previously unknown excited states in the daughter nucleus $^{172}\mathrm{Ir}$ is presented. An $\ensuremath{\alpha}$-decay branching ratio of ${b}_{\ensuremath{\alpha}}=9.5(11)%$ was deduced for the high-spin isomer in $^{172}\mathrm{Ir}$.
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- 2014
15. Decay of201–203Raand200–202Fr
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M. Venhart, Andrei Andreyev, R. D. Page, Bettina Lommel, L. Bianco, B. Andel, P. J. Sapple, Z. Kalaninová, Marc Huyse, J. Thomson, F. P. Heßberger, Dieter Ackermann, R. Mann, S. Antalic, Stefan G. Hofmann, Birgit Kindler, and P. Van Duppen
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Physics ,Nuclear and High Energy Physics ,Alpha decay ,Atomic physics - Abstract
Decay properties of the neutron-deficient nuclides ${}^{201--203}\mathrm{Ra}$ and ${}^{200--202}\mathrm{Fr}$ were investigated using $\ensuremath{\alpha}$- and $\ensuremath{\gamma}$-decay spectroscopy. The nuclei were produced in fusion-evaporation reactions of ${}^{56}$Fe projectiles with enriched ${}^{147}$Sm and ${}^{149}$Sm targets at the velocity filter SHIP at GSI in Darmstadt (Germany). The $\ensuremath{\alpha}$ decay from the (3/2${}^{\ensuremath{-}}$) state in ${}^{201}$Ra was identified with an energy ${E}_{\ensuremath{\alpha}}=7842(12)$ keV and half-life ${T}_{1/2}={8}_{\ensuremath{-}4}^{+40}$ ms. Ambiguous decay properties for ${}^{202}$Ra from previous measurements were clarified by remeasuring with significantly improved precision, resulting in values of ${E}_{\ensuremath{\alpha}}=7722(7)$ keV and ${T}_{1/2}=3.{8}_{\ensuremath{-}0.8}^{+1.3}$ ms. New short-lived isomeric states were identified in ${}^{200}$Fr and ${}^{201}$Fr with half-lives of 0.6${}_{\ensuremath{-}0.2}^{+0.5}$ $\ensuremath{\mu}$s and 0.7${}_{\ensuremath{-}0.2}^{+0.5}$ $\ensuremath{\mu}$s, respectively. A tentative spin and parity of 13/2${}^{+}$ were assigned to the latter. One event attributed to $\ensuremath{\beta}$-delayed fission of ${}^{200}$Fr was observed.
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- 2014
16. α-decay spectroscopy of the chain179Tlg→175Aug→171Irg→167Rem
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J. Khuyagbaatar, M. Sjödin, P. L. Molkanov, J. F. W. Lane, V. Liberati, B. A. Marsh, D. Radulov, R. Mann, Marc Huyse, M. D. Seliverstov, S. Heinz, Stefan G. Hofmann, S. Antalic, S. Franchoo, R. D. Page, O. Ivanov, Ulli Köster, N. Bree, Daniel Fink, S. Saro, I. Tsekhanovich, M. Veselský, J. Elseviers, V. N. Fedosseev, N. Patronis, Birgit Kindler, M. Venhart, P. Van Duppen, A. E. Barzakh, D. V. Fedorov, Thomas Elias Cocolios, Dieter Ackermann, D. Pauwels, Katsuhisa Nishio, Bettina Lommel, Jan Diriken, F. P. Heßberger, P. Van den Bergh, and A. N. Andreyev
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Physics ,Nuclear and High Energy Physics ,Chain (algebraic topology) ,010308 nuclear & particles physics ,Branching fraction ,0103 physical sciences ,Alpha decay ,Atomic physics ,010306 general physics ,Spectroscopy ,01 natural sciences - Abstract
Detailed $\ensuremath{\alpha}$-decay studies of ${}^{179}$Tl${}^{g}$ and its daughter products ${}^{175}$Au${}^{g}$ and ${}^{171}$Ir${}^{g}$ were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). First unambiguous determination of the $\ensuremath{\alpha}$-decay properties of ${}^{175}$Au${}^{g}$ was performed as follows: ${E}_{\ensuremath{\alpha}}$ $=$ 6433(4) keV, ${T}_{1/2}$ $=$ 207(7) ms, and $\ensuremath{\alpha}$-decay branching ratio 90(7)$%$. First determination of the $\ensuremath{\alpha}$-decay branching ratios for ${}^{179}$Tl${}^{g}$ and ${}^{171}$Ir${}^{g}$ was also made: ${b}_{\ensuremath{\alpha}}$(${}^{179}$Tl${}^{g}$) $=$ 60(2)$%$ and ${b}_{\ensuremath{\alpha}}$(${}^{171}$Ir${}^{g}$) $=$ 15(2)$%$. The spins of the ground states in ${}^{175}$Au and ${}^{171}$Ir are established as 1/2${}^{+}$.
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- 2013
17. αdecay of the very neutron-deficient isotopes197–199Fr
- Author
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F. P. Heßberger, Z. Kalaninová, P. Van Duppen, Marc Huyse, Dieter Ackermann, R. D. Page, J. F. W. Lane, A. Thornthwaite, Andrei Andreyev, V. Liberati, K. Sandhu, Birgit Kindler, Stefan G. Hofmann, Bettina Lommel, Michael Drummond, B. Andel, E. Rapisarda, S. Saro, and S. Antalic
- Subjects
Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Energy distribution ,chemistry ,Isotope ,chemistry.chemical_element ,Heavy ion ,Neutron ,Alpha decay ,Atomic physics ,Francium - Abstract
Decay properties of the very neutron-deficient isotopes ${}^{197\char21{}199}$Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the $2n\char21{}4n$ evaporation channels of the fusion-evaporation reaction ${}^{60}$Ni+${}^{141}$Pr $\ensuremath{\rightarrow}$ ${}^{201}$Fr*. Improved $\ensuremath{\alpha}$-decay properties of ${}^{199}$Fr were determined and the possible existence of two $\ensuremath{\alpha}$-decaying states in this nucleus is discussed. For the isotope ${}^{198}$Fr a broad $\ensuremath{\alpha}$-decay energy distribution was detected in the range of $(7470\char21{}7930)$ keV and two $\ensuremath{\alpha}$-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope ${}^{197}$Fr was identified based on the observation of one $\ensuremath{\alpha}$-decay chain yielding ${E}_{\ensuremath{\alpha}}=7728(15)$ keV and ${T}_{1/2}=0.{6}_{\ensuremath{-}0.3}^{+3.0}$ ms. The systematics of reduced $\ensuremath{\alpha}$-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes.
- Published
- 2013
18. β-delayed fission of192,194At
- Author
-
Dieter Ackermann, R. D. Page, S. Heinz, S. Antalic, S. Franchoo, F. P. Heßberger, Katsuhisa Nishio, Sigurd Hofmann, I. Kojouharov, Marc Huyse, Z. Kalaninová, B. Sulignano, P. Van Duppen, Bettina Lommel, R. Mann, Birgit Kindler, S. Saro, J. J. Ressler, A. N. Andreyev, B. Streicher, and L. Bianco
- Subjects
Physics ,Nuclear and High Energy Physics ,Cold fission ,Cluster decay ,010308 nuclear & particles physics ,Fission ,0103 physical sciences ,Beta (velocity) ,Atomic physics ,010306 general physics ,Kinetic energy ,01 natural sciences - Abstract
By using the recoil-fission correlation technique, the exotic process of beta-delayed fission ($\ensuremath{\beta}$DF) was unambiguously identified in the very neutron-deficient nuclei ${}^{192,194}$At in experiments at the velocity filter SHIP at Gesellschaft f\"ur Schwerionenforschung (GSI). The upper limits for the total kinetic energy release in fission of ${}^{192,194}$Po, being the daughter products of ${}^{192,194}$At after ${\ensuremath{\beta}}^{+}/EC$ decay, were estimated. The possibility of an unusually high $\ensuremath{\beta}$DF probability for ${}^{192}$At is discussed.
- Published
- 2013
19. β-delayed fission of186,188Bi isotopes
- Author
-
G. Münzenberg, S. Antalic, Sigurd Hofmann, Dieter Ackermann, J. F. W. Lane, H. Schaffner, A. N. Andreyev, Birgit Kindler, I. Kojouharov, A. Kleinböhl, Katsuhisa Nishio, Marc Huyse, F. P. Heßberger, Michael Taylor, P. Van Duppen, Bettina Lommel, Matti Leino, Heikki Kettunen, S. Saro, J. Gerl, and R. D. Page
- Subjects
Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Isotope ,010308 nuclear & particles physics ,Fission ,0103 physical sciences ,Beta (velocity) ,Nuclide ,010306 general physics ,01 natural sciences - Abstract
By using the technique of correlating implanted evaporation residues and their subsequent fission decay, $\ensuremath{\beta}$-delayed fission ($\ensuremath{\beta}$DF) of ${}^{186}$Bi has been identified for the first time and $\ensuremath{\beta}$DF of ${}^{188}$Bi has been unambiguously confirmed. The experiments were performed at the velocity filter SHIP (GSI, Darmstadt). The $\ensuremath{\beta}$DF probabilities for both nuclides were qualitatively estimated, and, in particular indications for a large value in the case of ${}^{186}$Bi are regarded.
- Published
- 2013
20. One-neutron removal reactions on Al isotopes around theN=20shell closure
- Author
-
P. Maierbeck, M. Winkler, A. Musumarra, Thomas Aumann, C. Scheidenberger, Isao Tanihata, Yu. A. Litvinov, Branislav Sitar, Rituparna Kanungo, Björn Jonson, D. Boutin, R. Krücken, C. Perro, R. Janik, F. Farinon, Mattias Lantz, Birgit Kindler, Bettina Lommel, M. Diakaki, N. Kurz, Barry Davids, Helmut Weick, D. Cortina-Gil, Imrich Szarka, Roman Gernhäuser, Thomas Nilsson, Peter Strmen, A. Prochazka, R. Knöbel, Bao-Hua Sun, H. Lenske, K. Mahata, C. Nociforo, and Hans Geissel
- Subjects
Physics ,Nuclear and High Energy Physics ,Momentum (technical analysis) ,Isotope ,Closure (computer programming) ,Shell (structure) ,Neutron ,Atomic physics ,Ground state ,Wave function ,Eikonal approximation - Abstract
The one-neutron removal cross sections of neutron-rich Al isotopes and longitudinal momentum distributions of the residues have been measured for A=33 to 36 at relativistic energies (≈900 MeV/u). The inclusive data have been interpreted within the eikonal approximation. The evolution of the single-particle occupancy in the ground state of 33,34,35Al has been studied and compared with shell model predictions. The inferred 2s1/2 neutron occupancy in the 33Al ground-state wave function is 20% to 40% lower than the predicted one. The inclusive data do not exclude the presence of intruder states. Some intruder l=1 occupancy is found in 34Al, similarly to 33Mg. The single-particle 1f7/2 occupancy shows a gradual increase at N=22. Correspondingly, a decrease of the 1d3/2 strength has been observed.
- Published
- 2012
21. Exploring the anomaly in the interaction cross section and matter radius of23O
- Author
-
Barry Davids, P. Maierbeck, C. Scheidenberger, Björn Jonson, M. Winkler, A. Musumarra, R. Krücken, Wataru Horiuchi, Bao-Hua Sun, H. Lenske, Yu. A. Litvinov, R. Janik, Yasuyuki Suzuki, Helmut Weick, Thomas Nilsson, C. Perro, Gaute Hagen, Birgit Kindler, D. Cortina-Gil, D. Boutin, F. Farinon, R. Knöbel, Branislav Sitar, Mattias Lantz, Thomas Aumann, R. Kanungo, Ø. Jensen, Hans Geissel, K. Mahata, M. Uchida, A. Prochazka, C. Nociforo, Imrich Szarka, Roman Gernhäuser, Peter Strmen, Bettina Lommel, J. Gerl, M. Diakaki, Isao Tanihata, and Thomas Papenbrock
- Subjects
Physics ,Nuclear and High Energy Physics ,Nuclear Theory ,010308 nuclear & particles physics ,Ab initio ,FOS: Physical sciences ,Radius ,01 natural sciences ,Isotopes of oxygen ,Nuclear Theory (nucl-th) ,Nuclear physics ,Cross section (physics) ,0103 physical sciences ,Neutron ,Nuclear Experiment (nucl-ex) ,Anomaly (physics) ,Nuclear Experiment ,010306 general physics ,Glauber ,Nuclear theory - Abstract
New measurements of the interaction cross sections of 22,23O at 900A MeV performed at the GSI, Darmstadt are reported that address the unsolved puzzle of the large cross section previously observed for 23O. The matter radii for these oxygen isotopes extracted through a Glauber model analysis are in good agreement with the new predictions of the ab initio coupled-cluster theory reported here. They are consistent with a 22O+neutron description of 23O as well., Comment: 4 pages, 3 figures
- Published
- 2011
22. Emission of clusters withZ>2from excited actinide nuclei
- Author
-
J. A. Heredia, S. Hofmann, V. F. Comas, G. G. Adamian, S. Heinz, Birgit Kindler, Werner Scheid, N. V. Antonenko, Jadambaa Khuyagbaatar, Sh. A. Kalandarov, Bettina Lommel, R. Mann, F. P. Heßberger, and Dieter Ackermann
- Subjects
Physics ,Nuclear and High Energy Physics ,Excited state ,Actinide ,Atomic physics - Published
- 2011
23. First superheavy element experiments at the GSI recoil separator TASCA: The production and decay of element 114 in thePu244(Ca48,3-4n) reaction
- Author
-
Susanta Lahiri, Andreas Türler, K. E. Gregorich, Dieter Ackermann, J. Krier, Matthias Schädel, Michael Block, Bettina Lommel, Petra Thörle-Pospiech, J. V. Kratz, H. Schaffner, R.-D. Herzberg, Klaus Eberhardt, Alexander Yakushev, A. V. Gorshkov, Dirk Rudolph, Jadambaa Khuyagbaatar, J. M. Gates, Ch. E. Düllmann, Moumita Maiti, F. P. Heßberger, Egon Jäger, Julia Even, Jnaneswari Gellanki, Jörg Runke, R. Graeger, B. Schausten, U. Forsberg, Birgit Kindler, E. Schimpf, W. Hartmann, Juha Uusitalo, M. Wegrzecki, J. Steiner, A. Semchenkov, A. Hübner, N. Kurz, W. Brüchle, H. G. Essel, P. A. Ellison, D. Liebe, Norbert Wiehl, J. P. Omtvedt, Heino Nitsche, E. Parr, J. Dvorak, D. Hild, and L. L. Andersson
- Subjects
Nuclear physics ,Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Isotope ,Neutron emission ,Transactinide element ,Decay chain ,Alpha decay ,Transuranium element ,Radioactive decay - 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. (Less)
- Published
- 2011
24. Matter radii of32−35Mg
- Author
-
Isao Tanihata, Yuri A. Litvinov, Wataru Horiuchi, Thomas Nilsson, R. Janik, Yasuyuki Suzuki, Christoph Scheidenberger, D. Cortina-Gil, Mattias Lantz, Birgit Kindler, Björn Jonson, J. Gerl, Roman Gernhäuser, D. Boutin, F. Farinon, R. Knöbel, R. Krücken, A. Musumarra, Yutaka Utsuno, Peter Strmen, R. Kanungo, K. Mahata, Barry Davids, C. Nociforo, M. Winkler, Thomas Aumann, Helmut Weick, P. Maierbeck, Bettina Lommel, C. Perro, H. Geissel, A. Prochazka, M. Diakaki, Imrich Szarka, Bao-Hua Sun, H. Lenske, and Branislav Sitar
- Subjects
Baryon ,Physics ,Nuclear physics ,Nuclear and High Energy Physics ,Hadron ,Neutron ,Elementary particle ,Atomic physics ,Nucleon ,Isotopes of magnesium ,Glauber ,Fermi Gamma-ray Space Telescope - Abstract
The interaction cross sections of Mg32-35 at 900A MeV have been measurmed using the fragment separator at GSI. The deviation from the r(0)A(1/3) trend is slightly larger for Mg-35, signaling the possible formation of a longer tail in the neutron distribution for Mg-35. The radii extracted from a Glauber model analysis with Fermi densities are consistent with models predicting the development of neutron skins.
- Published
- 2011
25. Nuclear orientation in the reactionS34+U238and synthesis of the new isotopeHs268
- Author
-
Sigurd Hofmann, A. V. Gorshkov, J. A. Heredia, R. Graeger, Jadambaa Khuyagbaatar, Y. Nagame, Tsutomu Ohtsuki, S. Heinz, R. Mann, H. Ikezoe, Kentaro Hirose, S. Saro, S. Antalic, A. V. Yeremin, Ch. E. Düllmann, Y. X. Watanabe, Andreas Türler, Katsuhisa Nishio, Yoshihiro Aritomo, Alexander Yakushev, Birgit Kindler, F. P. Heßberger, V. F. Comas, Ichiro Nishinaka, Dieter Ackermann, Matthias Schädel, S. Mitsuoka, Kouichi Hagino, I. Kojouharov, Bettina Lommel, and A. G. Popeko
- Subjects
Orientation (vector space) ,Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Uranium-238 ,chemistry ,chemistry.chemical_element ,Alpha decay ,Alpha particle ,Atomic physics ,Hassium ,Radioactive decay ,Spontaneous fission - Abstract
The synthesis of isotopes of the element hassium was studied using the reaction {sup 34}S+{sup 238}U{yields}{sup 272}Hs{sup *}. At a kinetic energy of 163.0 MeV in the center-of-mass system we observed one {alpha}-decay chain starting at the isotope {sup 267}Hs. The cross section was 1.8{sub -1.5}{sup +4.2} pb. At 152.0 MeV one decay of the new isotope {sup 268}Hs was observed. It decays with a half-life of 0.38{sub -0.17}{sup +1.8} s by 9479{+-}16 keV {alpha}-particle emission. Spontaneous fission of the daughter nucleus {sup 264}Sg was confirmed. The measured cross section was 0.54{sub -0.45}{sup +1.3} pb. In-beam measurements of fission-fragment mass distributions were performed to obtain information on the fusion probability at various orientations of the deformed target nucleus. The distributions changed from symmetry to asymmetry when the beam energy was changed from above-barrier to sub-barrier values, indicating orientation effects on fusion and/or quasifission. It was found that the distribution of symmetric mass fragments originates not only from fusion-fission, but has a strong component from quasifission. The result was supported by a calculation based on a dynamical description using the Langevin equation, in which the mass distributions for fusion-fission and quasifission fragments were separately determined.
- Published
- 2010
26. Experimental study of theU238(S36,3−5n)Hs269−271reaction leading to the observation ofHs270
- Author
-
R. Graeger, A. Hübner, M. L. Chelnokov, B. Schausten, Dirk Rudolph, Heino Nitsche, Andreas Türler, Julia Even, F. Samadani, J. V. Kratz, Dieter Ackermann, O. V. Petrushkin, Katsuhisa Nishio, A. V. Gorshkov, Bettina Lommel, Alexander Yakushev, J. Dvorak, D. Hild, A. A. Kuznetsov, Jadambaa Khuyagbaatar, Egon Jäger, Jörg Runke, J. Krier, Matthias Schädel, Ch. E. Düllmann, F. P. Heßberger, J. P. Omtvedt, Birgit Kindler, V. I. Chepigin, and Q. Zhi
- Subjects
Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Neutron emission ,Q value ,Evaporation ,Analytical chemistry ,Nuclear fusion ,Neutron ,Alpha decay ,Atomic physics ,Excitation - Abstract
The deformed doubly magic nucleus (270)Hs has so far only been observed as the four-neutron (4n) evaporation residue of the reaction Mg-26+Cm-248, where a maximum cross section of 3 pb was measured. Theoretical studies on the formation of (270)Hs in the 4n evaporation channel of fusion reactions with different entrance channel asymmetry in the framework of a two-parameter Smoluchowski equation predict that the reactions Ca-48+Ra-226 and S-36+U-238 result in higher cross sections due to lower reaction Q values, in contrast to simple arguments based on the reaction asymmetry, which predict opposite trends. Calculations using HIVAP predict cross sections for the reaction S-36+U-238 that are similar to those of the Mg-26+Cm-248 reaction. Here, we report on the first measurement of evaporation residues formed in the complete nuclear fusion reaction S-36+U-238 and the observation of (270)Hs, which is produced in the 4n evaporation channel, with a measured cross section of 0.8(-0.7)(+2.6) pb at 51-MeV excitation energy. The one-event cross-section limits (68% confidence level) for the 3n, 4n, and 5n evaporation channels at 39-MeV excitation energy are 2.9 pb, while the cross-section limits of the 3n and 5n channel at 51 MeV are 1.5 pb. This is significantly lower than the 5n cross section of the Mg-26+Cm-248 reaction at similar excitation energy.
- Published
- 2010
27. αdecay ofPb180,181
- Author
-
Thomas Elias Cocolios, I. Kojouharov, V. F. Comas, J. Khuyagbaatar, S. Heinz, S. Antalic, S. Franchoo, Marc Huyse, R. Mann, Stefan G. Hofmann, P. Van Duppen, S. Saro, H. V. Watkins, Dieter Ackermann, R. D. Page, J. A. Heredia, P. J. Sapple, A. N. Andreyev, S. Rinta-Antilla, F. P. Heßberger, M. Venhart, Bettina Lommel, J. Elseviers, and Birgit Kindler
- Subjects
Physics ,Nuclear and High Energy Physics ,010308 nuclear & particles physics ,0103 physical sciences ,Neutron ,Atomic physics ,Nuclear Experiment ,010306 general physics ,Ground state ,7. Clean energy ,01 natural sciences - Abstract
A detailed $\ensuremath{\alpha}$-decay study of the neutron-deficient isotope $^{181}\mathrm{Pb}$ has been performed in the complete fusion reaction $^{40}\mathrm{Ca}$$+$$^{144}\mathrm{Sm}$$\ensuremath{\rightarrow}$$^{184}\mathrm{Pb}$${}^{*}$ at the velocity filter SHIP (GSI, Darmstadt). In comparison with the literature, more precise data have been deduced for the ${I}^{\ensuremath{\pi}}=(9/{2}^{\ensuremath{-}})$ ground state in this nucleus, which is presumably based on the neutron $\ensuremath{\nu}{h}_{9/2}$ spherical orbital. Improved $\ensuremath{\alpha}$-decay data were also measured for $^{180}\mathrm{Pb}$.
- Published
- 2009
28. Identification and decay of the 0.48 ms13/2+isomer inHg181
- Author
-
Sigurd Hofmann, I. Kojouharov, J. A. Heredia, P. J. Sapple, Sami Rinta-Antila, Marc Huyse, J. Elseviers, Thomas Elias Cocolios, M. Venhart, H. V. Watkins, F. P. Heßberger, R. Mann, Dieter Ackermann, Bettina Lommel, J. Khuyagbaatar, Birgit Kindler, Andrei Andreyev, V. F. Comas, P. Van Duppen, S. Heinz, S. Antalic, S. Franchoo, S. Saro, and R. D. Page
- Subjects
Physics ,Nuclear and High Energy Physics ,Crystallography ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,0103 physical sciences ,Nuclear fusion ,Atomic physics ,Nuclear Experiment ,010306 general physics ,01 natural sciences - Abstract
A new isomer with a half-life of $0.48(2)$ ms was identified in the nuclide $^{181}\mathrm{Hg}$, which was produced in the complete fusion reaction $^{40}\mathrm{Ca}+^{144}\mathrm{Sm}\ensuremath{\rightarrow}^{184}\mathrm{Pb}$${}^{*}$ at the velocity filter SHIP (GSI, Darmstadt). The isomeric state was tentatively assigned a spin-parity of $13/{2}^{+}$. We propose that this isomer de-excites by a yet unobserved low-energy, strongly converted $\ensuremath{\gamma}$-ray transition, followed by a newly identified cascade composed of a $90.3$ keV $M1$ and a $71.4$ keV $E2$ $\ensuremath{\gamma}$-ray transition.
- Published
- 2009
29. Decay of the9/2−isomer inTl181and mass determination of low-lying states inTl181,Au177, andIr173
- Author
-
I. Kojouharov, V. F. Comas, Andrei Andreyev, J. Khuyagbaatar, R. Mann, J. Elseviers, Sigurd Hofmann, Thomas Elias Cocolios, R. D. Page, J. A. Heredia, F. P. Heßberger, M. Venhart, P. J. Sapple, Sami Rinta-Antila, Marc Huyse, Dieter Ackermann, Bettina Lommel, Birgit Kindler, P. Van Duppen, S. Saro, S. Heinz, S. Antalic, S. Franchoo, and H. V. Watkins
- Subjects
Physics ,Nuclear and High Energy Physics ,Decay scheme ,Mass excess ,010308 nuclear & particles physics ,Branching fraction ,01 natural sciences ,Intruder state ,0103 physical sciences ,Alpha decay ,Atomic physics ,010306 general physics ,Radioactive decay ,Excitation ,Dimensionless quantity - Abstract
A detailed spectroscopic study of the neutron-deficient isotope $^{181}\mathrm{Tl}$ and the daughter of its $\ensuremath{\alpha}$ decay, $^{177}\mathrm{Au}$, has been performed in the complete fusion reaction $^{40}\mathrm{Ca}+^{144}\mathrm{Sm}\ensuremath{\rightarrow}^{184}\mathrm{Pb}{}^{*}$ at the velocity filter SHIP (GSI). The mass excess, excitation energy, and decay scheme of the isomeric 1.40(3) ms, $9/{2}^{\ensuremath{-}}$ intruder state in $^{181}\mathrm{Tl}$ have been established for the first time. These results solve a long-standing puzzle of the unrealistically large reduced $\ensuremath{\alpha}$-decay width of this isomer. Based on this, the previously unknown masses of the long-lived isomeric states in $^{177}\mathrm{Au}$ and $^{173}\mathrm{Ir}$ have been derived. In turn, it now allows the excitation energies of previously identified bands in $^{177}\mathrm{Au}$ and $^{173}\mathrm{Ir}$ to be deduced and compared with theoretical predictions. First measurements of $\ensuremath{\alpha}$-decay branching ratios for $^{181}\mathrm{Tl}{}^{m}$ and $^{177}\mathrm{Au}{}^{m,g}$ are also reported.
- Published
- 2009
30. αdecay ofAt194
- Author
-
A. N. Andreyev, I. Kojouharov, Birgit Kindler, Sigurd Hofmann, P. Van Duppen, R. D. Page, P. J. Sapple, R. Mann, L. Bianco, S. Saro, B. Sulignano, S. Heinz, S. Antalic, S. Franchoo, M. Venhart, Mark Huyse, J. Thomson, F. P. Heßberger, Dieter Ackermann, Bettina Lommel, B. Streicher, J. J. Ressler, and Katsuhisa Nishio
- Subjects
Physics ,Nuclear and High Energy Physics ,Proton ,010308 nuclear & particles physics ,Fission ,01 natural sciences ,Nuclear physics ,Crystallography ,Atomic orbital ,0103 physical sciences ,Nuclear fusion ,Alpha decay ,010306 general physics ,Spectroscopy - Abstract
Detailed {alpha}-decay studies of the neutron-deficient isotope {sup 194}At have been performed in the complete fusion reaction {sup 56}Fe+{sup 141}Pr{yields}{sup 194}At+3n at the velocity filter SHIP. Two {alpha}-decaying isomeric states with half-lives of T{sub 1/2}({sup 194}At{sup m1})=310(8) ms and T{sub 1/2}({sup 194}At{sup m2})=253(10) ms were identified in this nucleus. Their complex decays to the states in the daughter nucleus {sup 190}Bi are discussed in the article. We propose that similar to the case of the neighboring {sup 191,192,193,195}At isotopes, the oblate-deformed configurations based on the proton 1/2{sup +}[440] and/or 7/2{sup -}[514] Nilsson orbitals become important in {sup 194}At. A new isomeric state with the half-life of 175(8) ns was observed in {sup 190}Bi.
- Published
- 2009
31. α decay of the new isotopesRn193,194
- Author
-
R. Mann, Robert Page, G. Münzenberg, Bettina Lommel, L. Bianco, I. Kojouharov, Mark Huyse, Ramon Wyss, B. Sulignano, Birgit Kindler, S. Saro, A. N. Andreyev, Dieter Ackermann, I. G. Darby, S. Antalic, S. Franchoo, B. Streicher, A.-P. Leppänen, J. J. Ressler, J. Thomson, F. P. Heßberger, Janne Pakarinen, D. M. Cullen, S. Heinz, S. Hofmann, and P. Van Duppen
- Subjects
Physics ,Nuclear and High Energy Physics ,Decay scheme ,Isotopes of germanium ,Isotope ,010308 nuclear & particles physics ,Isotopes of copper ,Radiochemistry ,Gamma ray ,01 natural sciences ,7. Clean energy ,Isotopes of oxygen ,Isotopes of protactinium ,0103 physical sciences ,Alpha decay ,Atomic physics ,010306 general physics - Abstract
The new neutron-deficient isotopes Rn-193,Rn-194 have been identified in the complete fusion reaction Cr-52+Sm-144 -> Rn-196(*) at the velocity filter SHIP. The alpha-decay energy and half-life value of Rn-194 were determined to be E-alpha=7700(10) keV and T-1/2=0.78(16) ms, respectively. For Rn-193 the half-life of T-1/2=1.15(27) ms and two alpha lines at E-alpha 1=7685(15) keV, I-alpha 1=74(20)% and E-alpha 2=7875(20) keV, I-alpha 2=26(12)% were found. The decay pattern of Rn-193, which is substantially different from that of the heavier odd-A Rn isotopes, provides first experimental evidence for the long-predicted deformation in the very neutron-deficient Rn nuclei.
- Published
- 2006
32. α-decay of the new isotopePo187: Probing prolate structures beyond the neutron mid-shell at N = 104
- Author
-
Mark Huyse, S. R. Lesher, P. Van Duppen, J. J. Ressler, Pasi Kuusiniemi, Dieter Ackermann, Bettina Lommel, Robert Page, Sigurd Hofmann, B. Sulignano, Ramon Wyss, Katsuhisa Nishio, R. Mann, S. Antalic, S. Franchoo, A. N. Andreyev, S. Saro, I. Kojouharov, B. Streicher, G. Münzenberg, D. R. Wiseman, F. P. Heßberger, and Birgit Kindler
- Subjects
Nuclear reaction ,Physics ,Nuclear and High Energy Physics ,010308 nuclear & particles physics ,01 natural sciences ,Excited state ,0103 physical sciences ,Potential energy surface ,Neutron ,Alpha decay ,Atomic physics ,010306 general physics ,Ground state ,Energy (signal processing) ,Radioactive decay - Abstract
The new neutron-deficient isotope $^{187}\mathrm{Po}$ has been identified in the complete fusion reaction $^{46}\mathrm{Ti}$+$^{144}\mathrm{Sm}$\ensuremath{\rightarrow}$^{187}\mathrm{Po}$+$3n$ at the velocity filter SHIP. Striking features of the $^{187}\mathrm{Po}$ \ensuremath{\alpha} decay are the strongly-hindered decay to the spherical ground state and unhindered decay to a surprisingly low-lying deformed excited state at 286 keV in the daughter nucleus $^{183}\mathrm{Pb}$. Based on the potential energy surface calculations, the $^{187}\mathrm{Po}$ ground state and the 286 keV excited state in $^{183}\mathrm{Pb}$ were interpreted as being of prolate origin. The systematic deviation of the \ensuremath{\alpha}-decay properties in the lightest odd-A Po isotopes relative to the smooth behavior in the even-A neighbors is discussed. Improved data for the decay of ${}^{187}{\mathrm{Bi}}^{m,g}$ were also obtained.
- Published
- 2006
33. α-decay spectroscopy of the new isotopeAt192
- Author
-
B. Streicher, G. Münzenberg, D. R. Wiseman, Sigurd Hofmann, F. P. Heßberger, Katsuhisa Nishio, Marc Huyse, Dieter Ackermann, R. Mann, R. D. Page, J. J. Ressler, Birgit Kindler, B. Sulignano, P. Van Duppen, S. Antalic, S. Franchoo, S. Saro, Andrei Andreyev, Pasi Kuusiniemi, I. Kojouharov, S. R. Lesher, and Bettina Lommel
- Subjects
Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Isotope ,Nuclear fusion ,Neutron ,Nuclide ,Alpha decay ,Atomic physics ,Spectroscopy - Abstract
Decay properties of the new neutron-deficient nuclide $^{192}\mathrm{At}$ have been studied in the complete fusion reaction $^{144}\mathrm{Sm}$($^{51}\mathrm{V}$,3n)$^{192}\mathrm{At}$ at the velocity filter SHIP. Two isomeric states with half-lives of 88(6) ms and 11.5(6) ms, respectively, and with complex $\ensuremath{\alpha}$-decay schemes were identified in $^{192}\mathrm{At}$. The decay pattern of one of the isomers suggests that it is based on the oblate-deformed $\ensuremath{\pi}2{f}_{7/2}\ensuremath{\bigotimes}\ensuremath{\nu}1{i}_{13/2}$ configuration, which confirms the expected onset of deformation in the At isotopes by approaching the neutron midshell at $N=104$.
- Published
- 2006
34. Cross section systematics for the lightest Bi and Po nuclei produced in complete fusion reactions with heavy ions
- Author
-
Sigurd Hofmann, Andrei Andreyev, R. Mann, G. Münzenberg, B. Sulignano, S. Antalic, Mark Huyse, Bettina Lommel, Pasi Kuusiniemi, D. R. Wiseman, P. Van Duppen, Robert Page, I. G. Darby, S. Saro, B. Streicher, S. Franchoo, K. Van de Vel, F. P. Heßberger, Dieter Ackermann, and Birgit Kindler
- Subjects
Nuclear physics ,Physics ,Nuclear and High Energy Physics ,Cross section (physics) ,Crystallography ,Fission ,Nuclear fusion ,Production (computer science) ,Neutron ,Alpha decay ,XX ,Nuclear Experiment ,Ion - Abstract
The production of the very neutron-deficient nuclides $^{184\ensuremath{-}192}\mathrm{Bi}$ and $^{186\ensuremath{-}192}\mathrm{Po}$ in the vicinity of the neutron midshell at N = 104 has been studied by using heavy-ion-induced complete fusion reactions in a series of experiments at the velocity filter SHIP. The cross sections for the xn and pxn evaporation channels of the $^{46}\mathrm{Ti}$+$^{144}\mathrm{Sm}$$\ensuremath{\rightarrow}^{190}\mathrm{Po}{}^{*},$$^{98}\mathrm{Mo}$+$^{92}\mathrm{Mo}$$\ensuremath{\rightarrow}^{190}\mathrm{Po}{}^{*},$$^{50,52}\mathrm{Cr}$+$^{142}\mathrm{Nd}$$\ensuremath{\rightarrow}^{192,194}\mathrm{Po}{}^{*}$, and $^{94,95}\mathrm{Mo}$+$^{93}\mathrm{Nb}$$\ensuremath{\rightarrow}^{187,188}\mathrm{Bi}{}^{*}$ reactions were measured. The results obtained, together with the previously known cross section data for the heavier Bi and Po nuclides, are compared with the results of statistical model calculations carried out with the HIVAP code. It is shown that a satisfactory description of the experimental data requires a significant (up to 35%) reduction of the theoretical fission barriers. The optimal reactions for production of the lightest Bi and Po isotopes are discussed.
- Published
- 2005
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