0000000000011212
AUTHOR
Heiko Scheit
showing 13 related works from this author
The neutron-rich Mg isotopes: first results from MINIBALL at REX-ISOLDE
2004
After the successful commissioning of the Radioactive beam EXperiment (REX) at ISOLDE (CERN) in 2002, first physics experiments were performed in 2003 which focussed on the neutron-rich Mg isotopes in the vicinity of the “island of inversion”. After introducing the REX facility and the modern γ spectrometer MINIBALL first preliminary results will be presented showing the high potential and physics opportunities offered by this new radioactive beam facility.
Measurement of the Dipole Polarizability of the Unstable Neutron-Rich NucleusNi68
2013
The E1 strength distribution in Ni68 has been investigated using Coulomb excitation in inverse kinematics at the RB3-LAND setup and by measuring the invariant mass in the one- and two-neutron decay channels. The giant dipole resonance and a low-lying peak (pygmy dipole resonance) have been observed at 17.1(2) and 9.55(17) MeV, respectively. The measured dipole polarizability is compared to relativistic random phase approximation calculations yielding a neutron-skin thickness of 0.17(2) fm. A method and analysis applicable to neutron-rich nuclei has been developed, allowing for a precise determination of neutron skins in nuclei as a function of neutron excess.
Development of quadrupole collectivity in the neutron-rich Ni, Zn, Ge, and Se isotopes
2003
An experiment was performed to study the collective properties of neutron-rich Ni, Zn, Ge, and Se isotopes. Of particular interest is the vicinity of the N = 50 and Z = 28 shell closures. For most neutron-rich nuclei in this region of the chart of nuclei the B(E2) values of the transitions from the ground to the first excited 2+ states are unknown. This information would give valuable insight into the changes in nuclear structure when going to more neutron-rich nuclei.
“Safe” Coulomb Excitation ofMg30
2005
We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)R 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the …
Sub-Barrier Coulomb Excitation ofSn110and Its Implications for theSn100Shell Closure
2007
The first excited 2(+) state of the unstable isotope Sn-110 has been studied in safe Coulomb excitation at 2.82 MeV/u using the MINIBALL array at the REX-ISOLDE post accelerator at CERN. This is the first measurement of the reduced transition probability of this state using this method for a neutron deficient Sn isotope. The strength of the approach lies in the excellent peak-to-background ratio that is achieved. The extracted reduced transition probability, B(E2 : 0(+) -> 2(+)) 0.220 +/- 0.022e(2) b(2), strengthens the observation of the evolution of the B(E2) values of neutron deficient Sn isotopes that was observed recently in intermediate-energy Coulomb excitation of Sn-108. It implies …
Coulomb breakup of psd-shell neutron-rich nuclei
2005
Inelastic scattering of loosely bound nuclei by Coulomb interaction at intermediate energies (400?600 MeV/nucleon) has been utilized as a spectroscopic tool for exotic nuclei. The observed electromagnetic dipole (E1) strength above the one neutron threshold of neutron-rich C, Be, B and O isotopes can be explained by a non-resonant transition of a neutron into the continuum. The shape of these strength distributions reflects properties of the wavefunction of the released neutron in the nucleus and hence ground-state properties of these isotopes. Neutron capture cross-sections such as for the 14C(n,?) 15C reaction which are of astrophysical relevance can be deduced indirectly.
Coulomb Excitation of Neutron-Rich Zn Isotopes: First Observation of the21+State inZn80
2007
Neutron-rich, radioactive Zn isotopes were investigated at the Radioactive Ion Beam facility REX-ISOLDE (CERN) using low-energy Coulomb excitation. The energy of the 2(1)+ state in 78Zn could be firmly established and for the first time the 2+ --> 0(1)+ transition in 80Zn was observed at 1492(1) keV. B(E2,2(1)+ --> 0(1)+) values were extracted for (74,76,78,80)Zn and compared to large scale shell model calculations. With only two protons outside the Z=28 proton core, 80Zn is the lightest N=50 isotone for which spectroscopic information has been obtained to date. Two sets of advanced shell model calculations reproduce the observed B(E2) systematics. The results for N=50 isotones indicate a g…
Coulomb breakup of 23O
2005
Abstract The ground-state structure of the near-drip-line nucleus 23O has been investigated in a one-neutron Coulomb breakup reaction. Differential cross sections d σ / d E * for electromagnetic excitation of 23O projectiles (422 MeV/nucleon) incident on a lead target have been obtained from the measurement of the momenta of all breakup products including γ rays. The analysis of the deduced dipole-transition probability into the continuum infers a 2 s 1 / 2 ⊗ O 22 ( 0 + ) ground state configuration with a spectroscopic factor of 0.77(10) and thus a ground-state spin I π ( O 23 ) = 1 / 2 + , resolving earlier conflicting experimental findings. Final-state interaction is of significant influe…
Investigation of the Li9+H2→Li8+t reaction at REX-ISOLDE
2006
The one-neutron transfer reaction Li-9 + H-2 -> Li-8 + t has been investigated in an inverse kinematics experiment by bombarding a deuterated polypropylene target with a 2.36 MeV/u Li-9 beam from the post-accelerator REX-ISOLDE at CERN. Excitation energies in Li-8 as well as angular distributions of the tritons were obtained and spectroscopic factors deduced. (c) 2006 Elsevier B.V. All rights reserved.
The Miniball spectrometer
2013
The Miniball germanium detector array has been operational at the REX (Radioactive ion beam EXperiment) post accelerator at the Isotope Separator On-Line facility ISOLDE at CERN since 2001. During the last decade, a series of successful Coulomb excitation and transfer reaction studies have been performed with this array, utilizing the unique and high-quality radioactive ion beams which are available at ISOLDE. In this article, an overview is given of the technical details of the full Miniball setup, including a description of the γ-ray and particle detectors, beam monitoring devices and methods to deal with beam contamination. The specific timing properties of the REX-ISOLDE facility are hi…
Coulomb Excitation ofCu68,70: First Use of Postaccelerated Isomeric Beams
2007
We report on the first low-energy Coulomb excitation measurements with radioactive Ipi=6- beams of odd-odd nuclei 68,70Cu. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon. gamma rays were detected with the MINIBALL spectrometer. The 6- beam was used to study the multiplet of states (3-, 4-, 5-, 6-) arising from the pi2p3/2nu1g9/2 configuration. The 4- state of the multiplet was populated via Coulomb excitation and the B(E2;6--->4-) value was determined in both nuclei. The results obtained illustrate the fragile stability of the Z=28 shell and N=40 subshell closures. A comparison with large-scale shell-model calculations using the 56Ni core…
Accelerated radioactive beams from REX-ISOLDE
2003
In 2001 the linear accelerator of the Radioactive beam EXperiment (REX-ISOLDE) delivered for the first time accelerated radioactive ion beams, at a beam energy of 2 MeV/u. REX-ISOLDE uses the method of charge-state breeding, in order to enhance the charge state of the ions before injection into the LINAC. Radioactive singly-charged ions from the on-line mass separator ISOLDE are first accumulated in a Penning trap, then charge bred to an A/q < 4.5 in an electron beam ion source (EBIS) and finally accelerated in a LINAC from 5 keV/u to energies between 0.8 and 2.2 MeV/u. Dedicated measurements with REXTRAP, the transfer line and the EBIS have been carried out in conjunction with the first co…
Low energy reactions with radioactive ions at REX-ISOLDE-the 9Li + 2H case
2005
19 pages, 12 figures, 2 tables.-- PACS nrs.: 25.60.-t; 25.45.-z; 27.20.+n.-- et al. ISOLDE Collaborattion and REX-ISOLDE Collaboration.