Michael Block

Michael Block
GSI Helmholtzzentrum für Schwerionenforschung | GSI · Nuclear Physics

Professor

About

251
Publications
20,123
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5,391
Citations
Additional affiliations
January 2012 - present
January 2011 - present
January 2011 - present
Justus-Liebig-Universität Gießen

Publications

Publications (251)
Article
The neutron-deficient Bi188 and Po188 isotopes have been studied by γ-ray spectroscopy using the recoil-decay tagging technique with the Argonne Gas-Filled Analyzer. A new 0.25(5)-μs isomeric state and a prompt cascade formed by 319-, 366-, and 462-keV γ rays have been established on top of the (10−) α-decaying isomer in Bi188. The first excited (2...
Article
The decay of the 13/2⁺ isomeric state in ¹⁸³Hg was observed for the first time following the α decay of the 13/2⁺ isomer in ¹⁸⁷Pb produced in the ¹⁴²Nd(⁵⁰Cr, 2p3n) reaction. Using α−γ delayed coincidence measurements, the half-life of this isomer was measured to be 290(30) μs. This isomer is proposed to deexcite by an unobserved low-energy M2 trans...
Article
Full-text available
Laser spectroscopic studies of elements in the heavy actinide and transactinide region help understand the nuclear ground state properties of these heavy systems. Pioneering experiments at GSI, Darmstadt identified the first atomic transitions in the element nobelium. For the purpose of determining nuclear properties in nobelium isotopes with highe...
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The four-component relativistic Dirac–Coulomb Hamiltonian and the multireference configuration interaction (MRCI) model were used to provide the reliable energy levels and spectroscopic properties of the Lr+ ion and the Lu+ homolog. The energy spectrum of Lr+ is very similar to that of the Lu+ homolog, with the multiplet manifold of the 7s2, 6d17s1...
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Superheavy element research has been a strong pillar of the research program at GSI Darmstadt since its foundation. Six new elements were discovered along with many new isotopes. Initial results on chemical properties of the heaviest elements were obtained that allowed for comparing their behavior with that of their lighter homologs and with theore...
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RAdiation-Detected Resonance Ionization Spectroscopy (RADRIS) is a versatile method for highly sensitive laser spectroscopy studies of the heaviest actinides. Most of these nuclides need to be produced at accelerator facilities in fusion-evaporation reactions and are studied immediately after their production and separation from the primary beam du...
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Prompt and delayed γ-ray spectroscopy of the neutron-deficient, semi-magic isotope ¹⁸⁷Pb has been performed using the recoil-decay and isomer-decay tagging techniques at the Argonne Gas-Filled Analyzer. A new 5.15(15)-μs isomeric state at only 308 keV above the spherical 3/2⁻ ground state is identified and classified as a shape isomer. A strongly-c...
Preprint
Two-ion crystals constitute a platform for investigations of quantum nature that can be extended to any ion species or charged particle provided one of the ions in the crystal can be directly laser-cooled and manipulated with laser radiation. This paper presents the formation of two-ion crystals for quantum metrology in a 7-tesla open-ring Penning...
Article
Understanding the atomic and nuclear properties of very heavy and superheavy nuclides is one of the main objectives in experiments at the recoil separator SHIP at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. This article summarizes recent experiments performed on isotopes of the elements with Z = 102–105. The radionuclid...
Article
Alpha decay and spontaneous fission of the ground-state and the isomeric state of $$^{247}$$ 247 Md were investigated with specific emphasis to identify the ground-state of the daughter nucleus $$^{243}$$ 243 Es. The decay studies were accompanied by measuring $$\alpha $$ α - $$\gamma $$ γ coincidences. On the basis of the measured data an improved...
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Nihonium (Nh, element 113) and flerovium (Fl, element 114) are the first superheavy elements in which the 7p shell is occupied. High volatility and inertness were predicted for Fl due to the strong relativistic stabilization of the closed 7p 1/2 sub-shell, which originates from a large spin-orbit splitting between the 7p 1/2 and 7p 3/2 orbitals. On...
Article
A novel combination of advanced gas-chromatography and detection systems coupled to a buffer-gas cell was characterized on-line to allow gas-phase chemical studies of accelerator-produced short-lived α-decaying mercury, francium, and astatine isotopes. These were produced in ⁴⁰Ar- and ⁴⁸Ca-induced nuclear fusion–evaporation reactions, subsequently...
Article
We report calculation of the energy spectrum and the spectroscopic properties of the superheavy element ion: Rf+. We use the four-component relativistic Dirac-Coulomb Hamiltonian and the multireference configuration interaction model to tackle the complex electronic structure problem that combines strong relativistic effects and electron correlatio...
Preprint
We report calculation of the energy spectrum and the spectroscopic properties of the superheavy element ion: Rf^+. We use the 4-component relativistic Dirac-Coulomb Hamiltonian and the multireference configuration interaction (MRCI) model to tackle the complex electronic structure problem that combines strong relativistic effects and electron corre...
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Full-text available
The coherent coupling between a quartz electro-mechanical resonator at room temperature and trapped ions in a 7 T Penning trap has been demonstrated for the first time. The signals arising from the coupling remain for integration times in the orders of seconds. From the measurements carried out, we demonstrate that the coupling allows detecting the...
Article
In two recent papers by Pore et al. and Khuyagbaatar et al., discovery of the new isotope Md244 was reported. The decay data, however, are conflicting. While Pore et al. report two isomeric states decaying by α emission with Eα(1)=8.66(2) MeV, T1/2(1)=0.4−0.1+0.4 s and Eα(2)=8.31(2) MeV, T1/2(2)≈6 s, Khuyagbaatar et al. [Phys. Rev. Lett. 125, 14250...
Preprint
The coherent coupling between a quartz electro-mechanical resonator at room temperature and trapped ions in a 7-tesla Penning trap has been demonstrated for the first time. The signals arising from the coupling remain for integration times in the orders of seconds. From the measurements carried out, we demonstrate that the coupling allows detecting...
Article
To study the chemical properties of the heaviest elements, a fast and efficient stopping and extraction of the highly energetic residues from heavy ion fusion reactions into the chemistry setup is essential. Currently used techniques like Recoil Transfer Chambers (RTC) relying on gas flow extraction provide high efficiencies for chemically non-reac...
Article
Full-text available
A nuclear spectroscopy experiment was conducted to study α-decay chains stemming from isotopes of flerovium (element Z=114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions Ca48+Pu242 and Ca48+Pu244 provid...
Preprint
In two recent papers by Pore et al. and Khuyagbaatar et al. discovery of the new isotope Md-244 was reported. The decay data, however, are conflicting. While Pore et al. report two isomeric states decaying by alpha emission with E(1)=8.66(2) MeV, T_1/2=0.4+0.4/-0.1s and E(2)=8.31(2) MeV, T_1/2 approx 6 s, Khuyagbaatar et al. report only a single tr...
Article
Full-text available
The sensitive RAdiation Detected Resonance Ionization Spectroscopy (RADRIS) technique enabled the study of the atomic structure of the element nobelium (No, Z = 102) for the first time. The prospect of accessing the next element, lawrencium (Lr, Z = 103), depends on the efficiency and speed of evaporation of sample atoms from a filament catcher. To...
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A gas-filled miniature Radio-Frequency Quadrupole (mini-RFQ) was recently implemented into the SHIPTRAP laser ablation ion source to thermalize the laser-ablated ions and thus improve production efficiency as well as sample preparation. This source provides reference ions of various elements for online experiments with the SHIPTRAP mass spectromete...
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Relativistic effects strongly influence the chemical and physical properties of the heaviest elements, which can significantly differ from the periodicity predicted by the periodic table of elements. Former systematic mobility measurements on monoatomic lanthanide ions revealed the dependence of ion-atom interactions on the underlying electronic co...
Article
Full-text available
An upgraded TASISpec setup, with the addition of a veto DSSD and the new Compex detector-germanium array, has been employed with the gas-filled recoil separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung Darmstadt, to study flerovium (element 114) decay chains. The detector upgrades along with development of new analytical technique...
Preprint
The interest to perform laser spectroscopy in the heaviest elements arises from the strong impact of relativistic effects, electron correlations and quantum electrodynamics on their atomic structure. Once this atomic structure is well understood, laser spectroscopy also provides access to nuclear properties such as spins, mean square charge radii a...
Preprint
The electron-capture decay followed by a prompt fission process was searched for in the hitherto unknown most neutron-deficient Md isotope with mass number 244. Alpha decay with α-particle energies of 8.73–8.86 MeV and with a half-life of 0.30−0.09+0.19 s was assigned to Md244. No fission event with a similar half-life potentially originating from...
Article
We report on cyclotron frequency measurements on trapped 206,207Pb⁺ ions by means of the non-destructive Fourier-transform ion-cyclotron-resonance technique at room temperature. In a proof-of-principle experiment using a quartz crystal instead of a coil as a resonator, we have alternately carried out cyclotron frequency measurements for ²⁰⁶Pb⁺ and...
Article
We report on the successful coupling of the Penning-trap mass spectrometry setup TRIGA-TRAP to the research reactor TRIGA Mainz. This offers the possibility to perform direct high-precision mass measurements of short-lived nuclei produced in neutron-induced fission of a 235U target located near the reactor core. An aerosol-based gas-jet system is u...
Article
Spontaneous fission properties of the isotopes Rf255, Rf256, and Rf258 produced in the reactions Ti50+Pb207, Ti50+Pb208, and Ti50+Bi209 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 s...
Article
In this paper, the dynamics of an unbalanced two-ion crystal comprising the “target” and the “sensor” ions confined in a Penning trap along the magnetic-field axis has been studied. First, the low amplitude regime is addressed. In this regime, the overall potential including the Coulomb repulsion between the ions can be considered harmonic and the...
Article
The neutron-deficient isotopes 254,255Rf were produced in the fusion-evaporation reaction ⁵⁰Ti + ²⁰⁶Pb at the gas-filled recoil separator TASCA. Decay properties of these nuclei were investigated by applying fast digital electronics. A search for isomeric states in both isotopes was performed by using the accompanying conversion electron emissions....
Preprint
In this article, the dynamics of an unbalanced two-ion crystal comprising the 'target' and the 'sensor' ions confined in a Penning trap has been studied. First, the low amplitude regime is addressed. In this regime, the overall potential including the Coulomb repulsion between the ions can be considered harmonic and the axial, magnetron and reduced...
Article
Im ersten Jahrgang von Physik in unserer Zeit im Jahre 1970 erschien eine Meldung zur Namensgebung des superschweren Elements 105. Was wurde daraus, und wo stehen wir heute?
Article
The precise determination of atomic and nuclear properties such as masses, differential charge radii, nuclear spins, electromagnetic moments and the ionization potential of the actinides has been extended to the late actinides in recent years. In particular, laser spectroscopy and mass spectrometry have reached the region of heavy actinides that ca...
Article
Single-ion sensitivity is obtained in precision Penning-trap experiments devoted to light (anti)particles or ions with low mass-to-charge ratios, by adding an inductance coil to an amplifier connected to the trap, both operated at 4 K. However, single-ion sensitivity has not been reached on heavy singly or doubly charged ions. In this publication,...
Article
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 r...
Article
Fusion-evaporation reactions with the doubly magic projectile ⁴⁸ Ca were used to access neutron-deficient nuclei around neptunium at the velocity filter SHIP, and investigated using the COMPASS decay spectroscopy station. With the use of digital electronics, several isotopes produced via neutron, proton, and α evaporation channels were identified b...
Article
Direct high-precision mass spectrometry of the heaviest elements with SHIPTRAP, at GSI in Darmstadt, Germany, requires high efficiency to deal with the low production rates of such exotic nuclides. A second-generation gas stopping cell, operating at cryogenic temperatures, was developed and recently integrated into the relocated system to boost the...
Article
Laser spectroscopy enables the determination of fundamental atomic and nuclear properties with high precision. In view of the low production rates of the heaviest elements, a high total efficiency is a crucial requirement for any experimental setup to be used in on-line experiments. The setup requires the use of gas stopping techniques to slow down...
Article
The precise determination of atomic and nuclear properties such as masses, differential charge radii, nuclear spins and electromagnetic moments of exotic nuclides has recently been extended to the region of the heaviest elements. To this end, ion trap-based techniques and laser spectroscopy methods have been employed to provide information compleme...
Article
Abstract Gas catchers are widely used to thermalize nuclear reaction products and subsequently extract them for precision measurements. However, impurities in the inert stopping gas can chemically react with the ions and thus influence the extraction efficiency. So far, chemical reactions in the gas-catcher have not been investigated in detail. The...
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Full-text available
A Penning-trap facility for high-precision mass spectrometry based on a novel detection method has been built. This method consists in measuring motional frequencies of singly-charged ions trapped in strong magnetic fields through the fluorescence photons from laser-cooled ⁴⁰ Ca ⁺ ions, to overcome limitations faced in electronic single-ion detecti...
Article
Full-text available
The superheavy isotope ²⁵⁸Db was produced in the ²⁰⁹Bi(⁵⁰Ti, 1n)²⁵⁸Db reaction at GSI, Germany. A detailed \( \alpha\)-spectroscopy study of this isotope and its \( \alpha\)-decay daughter products was performed. Two long-lived \( \alpha\)-decaying states in ²⁵⁸Db are observed. A spin-parity of \( 0^{-}\) is tentatively assigned to the ground state...
Article
Full-text available
The isotopes 255,256,258 Rf were produced in the fusion-evaporation reactions ⁵⁰ Ti + 207,208 Pb and ⁵⁰ Ti + ²⁰⁹ Bi at GSI Darmstadt, using the velocity filter SHIP. Total kinetic energies of fragments from spontaneous fission for these isotopes were evaluated with a correction to pulse-height defect.
Article
Short-lived α-decaying nuclei “northeast” of Pb208 in the chart of nuclides were studied using the reaction Ca48+Am243 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 analy...
Preprint
Full-text available
The Penning-trap electronic-detection technique that offers the precision and sensitivity requested in mass spectrometry for fundamental studies in nuclear and particle physics has not been proven yet to be universal. This has motivated the construction of a Penning-trap facility aiming at the implementation of a novel detection method, consisting...
Article
Die Größe und Form künstlich hergestellter Atomkerne mit mehr als hundert Protonen ließ sich bislang experimentell nicht direkt ermitteln. Mit Hilfe einer neuen laserspektroskopischen Methode ist es unserer Kollaboration gelungen, die optische Anregung von Energieniveaus in der Atomhülle von drei Isotopen des schweren synthetischen Elements Nobeliu...
Article
Online gas-solid adsorption studies with single-atom quantities of Hg, Tl, and Pb, the lighter homologs of the superheavy elements (SHE) copernicium (Cn, Z =112), nihonium (Nh, Z =113), and flerovium (Fl, Z =114), were carried out using short-lived radioisotopes. The interaction with Au and SiO 2 surfaces was studied and the overall chemical yield...
Article
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-evap...
Article
One of the most important atomic properties governing an element’s chemical behavior is the energy required to remove its least-bound electron, referred to as the first ionization potential. For the heaviest elements, this fundamental quantity is strongly influenced by relativistic effects which lead to unique chemical properties. Laser spectroscop...
Article
Until recently, ground-state nuclear moments of the heaviest nuclei could only be inferred from nuclear spectroscopy, where model assumptions are required. Laser spectroscopy in combination with modern atomic structure calculations is now able to probe these moments directly, in a comprehensive and nuclear-model-independent way. Here we report on u...
Article
A race is on to create the world's heaviest elements—and to explore the periodic table's “island of stability,” where these elements exist for more than a moment
Article
A compact silicon detector array with high spatial granularity and fast, fully digital data recording has been developed and commissioned for the investigation of heavy and superheavy nuclear species. The detector array can be combined in close geometry with large volume germanium detectors. It offers comprehensive particle and photon coincidence a...
Article
Full-text available
The in-gas laser ionization and spectroscopy (IGLIS) technique was applied on the Ac212–215 isotopes, produced at the Leuven Isotope Separator On-Line (LISOL) facility by using the in-gas-cell and the in-gas-jet methods. The first application under on-line conditions of the in-gas-jet laser spectroscopy method showed a superior performance in terms...
Article
An experimental scheme combining the mass resolving power of a Penning trap with contemporary decay spectroscopy has been established at GSI Darmstadt. The Universal Linear Accelerator (UNILAC) at GSI Darmstadt provided a Ca48 beam impinging on a thin Er170 target foil. Subsequent to velocity filtering of reaction products in the Separator for Heav...
Article
Using the sensitive Radiation Detected Resonance Ionization Spectroscopy (RADRIS) technique an optical transition in neutral nobelium (No, Z = 102) was identified. A remnant signal when delaying the ionizing laser indicated the influence of a strong buffer gas induced de-excitation of the optically populated level. A subsequent investigation of the...
Article
Full-text available
Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we d...
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The X. international workshop on “Application of Lasers and Storage Devices in Atomic Nuclei Research” took place in Poznan in May 2016. It addressed the latest experimental and theoretical achievements in laser and ion trap-based investigations of radionuclides, highly charged ions and antiprotons. The precise determination of atomic and nuclear p...
Article
Masses of $^{52}$Co, $^{52}$Co$^m$, $^{52}$Fe, $^{52}$Fe$^m$, and $^{52}$Mn have been measured with the JYFLTRAP double Penning trap mass spectrometer. Of these, $^{52}$Co and $^{52}$Co$^m$ have been experimentally determined for the first time and found to be more bound than predicted by extrapolations. The isobaric multiplet mass equation for the...
Article
With the Penning-trap mass spectrometer SHIPTRAP at GSI, Darmstadt, it is possible to investigate exotic nuclei in the region of the heaviest elements. Few years ago, challenging experiments led to the direct measurements of the masses of neutron-deficient isotopes with Z = 102; 103 around N = 152. Thanks to recent advances in cooling and ion-manip...
Article
Full-text available
Laser spectroscopy of the heaviest elements provides high-precision data on their atomic and nuclear properties. For example, atomic level energies and ionization potentials allow us to probe the influence of relativistic effects on their atomic structure and to benchmark state-of-the-art atomic structure calculations. In addition, it offers an alt...