Search results for "Island"
showing 10 items of 761 documents
Isotope shift, non-linearity of King plots and the search for new particles
2017
We derive a mean-field relativistic formula for the isotope shift of an electronic energy level for arbitrary angular momentum; we then use it to predict the spectra of superheavy metastable neutron-rich isotopes belonging to the hypothetical island of stability. Our results may be applied to the search for superheavy atoms in astrophysical spectra using the known values of the transition frequencies for the neutron deficient isotopes produced in the laboratory. An example of a relevant astrophysical system may be the spectra of the Przybylski's star where superheavy elements up to Z=99 have been possibly identified. In addition, it has been recently suggested to use the measurements of Kin…
Production and properties towards the island of stability
2016
The structure of the nuclei of the heaviest elements is discussed with emphasis on single-particle properties as determined by decay and inbeam spectroscopy. The basic features of production of these nuclei using fusion evaporation reactions will also be discussed. peerReviewed
Spectroscopy along Flerovium Decay Chains: Discovery ofDs280and an Excited State inCn282
2021
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 fur Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions ^{48}Ca+^{242}Pu and ^{48}Ca+^{244}Pu provided a total of 32 flerovium-candidate decay chains, of which two and eleven were firmly assigned to ^{286}Fl and ^{288}Fl, respectively. A prompt coincidence between a 9.60(1)-MeV α particle event and a 0.36(1)-MeV conversion electron marked the first observation of an excited state in an even-even isotope of the heaviest man-made eleme…
A step further in the A = 33−35, N ≃ 21, island of inversion: the structure of 33Mg
2003
Experimental indications have been found in the seventies for the deformation of neutron-rich A ≃ 32 nuclei [1]. This could be explained by Hartree-Fock calculations, predicting deformed configurations in the ground state of nuclei in the A = 33−35, N ≃ 21 mass region. This exotic region, called the island of inversion [2], knows a renewed interest since it can be now experimentally accessible for detailed studies.
Nuclear Charge Radii ofMg21−32
2012
Charge radii of all magnesium isotopes in the sd shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on (24)Mg and (32)Mg. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards N=8 and collectivity near N=20 is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.
Measurement of the Spin and Magnetic Moment ofMg31: Evidence for a Strongly Deformed Intruder Ground State
2005
Unambiguous values of the spin and magnetic moment of $^{31}\mathrm{M}\mathrm{g}$ are obtained by combining the results of a hyperfine-structure measurement and a $\ensuremath{\beta}$-NMR measurement, both performed with an optically polarized ion beam. With a measured nuclear $g$ factor and spin $I=1/2$, the magnetic moment $\ensuremath{\mu}(^{31}\mathrm{M}\mathrm{g})=\ensuremath{-}0.88355(15){\ensuremath{\mu}}_{N}$ is deduced. A revised level scheme of $^{31}\mathrm{M}\mathrm{g}$ ($Z=12$, $N=19$) with ground state spin/parity ${I}^{\ensuremath{\pi}}=1/{2}^{+}$ is presented, revealing the coexistence of 1p-1h and 2p-2h intruder states below 500 keV. Advanced shell-model calculations and th…
Direct Mapping of Nuclear Shell Effects in the Heaviest Elements
2014
Quantum-mechanical shell effects are expected to strongly enhance nuclear binding on an "island of stability" of superheavy elements. The predicted center at proton number $Z=114,120$, or $126$ and neutron number $N=184$ has been substantiated by the recent synthesis of new elements up to $Z=118$. However the location of the center and the extension of the island of stability remain vague. High-precision mass spectrometry allows the direct measurement of nuclear binding energies and thus the determination of the strength of shell effects. Here, we present such measurements for nobelium and lawrencium isotopes, which also pin down the deformed shell gap at $N=152$.
Bridging the nuclear structure gap between stable and super heavy nuclei
2009
International audience; Due to recent advances in detection techniques, excited states in several trans-fermium nuclei were studied in many laboratories worldwide, shedding light on the evolution of nuclear structure between stable nuclei and the predicted island of stability centered around spherical magic numbers. In particular, studies of K-isomers around the Z=100 and N=152 deformed shell closures extended information on the energies of Nilsson orbitals at the Fermi surface. Some of these orbitals originate from spherical states, which are relevant to the magic gaps in super-heavy nuclei. The single-particle energies can be used to test various theoretical predictions and aid in extrapo…
Surveying the N=40 island of inversion with new manganese masses
2012
High-precision mass measurements of neutron-rich 57−66Mn and 61−63Fe isotopes are reported. The new mass surface shows no shell closure at N=40. In contrast, there is an increase of the two-neutron separation energy at N=38. This behavior is consistent with the onset of collectivity due to the occupation of intruder states from higher orbits, in analogy with the well known “island of inversion” around N=20. Our results indicate that the neutron-rich Mn isotopes, starting from 63Mn, are most likely within the new island of inversion. From the new mass surface, we evaluate the empirical proton-neutron interaction and the pairing gap, both playing a significant role in the structural changes i…
Intruder features in the island of inversion: The case of33Mg
2001
The Na-33 beta decay was studied online using mass separation techniques and a first description of the level structure of the neutron-rich isotope Mg-33, with N=21, has been obtained. The experiment involved the measurement of beta-gamma, beta-gamma-gamma, and beta -n-gamma coincidences as well as neutron spectra by time-of-flight technique. The first low energy level scheme for the daughter nucleus Mg-33 is given with five bound states. Spin and parity assignments are proposed according to beta feedings and gamma -ray multipolarities, beta -strength distribution is evaluated, taking into account 1n- and 2n-emission channels and it is compared with the calculated GT strength distribution. …