P. Doornenbal

Isomeric decay studies in neutron-rich N ≈ 126 nuclei

Heavy neutron-rich nuclei were populated via relativistic energy fragmentation of a E/A = 1 GeV208Pb beam. The nuclei of interest were selected and identified by a fragment separator and then implanted in a passive plastic stopper. Delayed γ rays following internal isomeric decays were detected by the RISING array. Experimental information was obtained on a number of nuclei with Z = 73-80 (Ta-Hg), providing new information both on the prolate-oblate transitional region as well as on the N = 126 closed shell nuclei.

Isomeric mirror states as probes for effective charges in the lower pf shell

Following the fragmentation of a 550 MeV u −1 primary beam of 58 Ni, timeand energy-correlated γ decays from isomeric states in neutron-deficient nuclei in the 1f7/2 shell have been identified using the GSI fragment separator in combination with the RISING Ge-detector array. The results on isomers in the mirror pairs 43 Ti 21 – 43 Sc 22 (I π = 3/2 + and 19/2 − ), 45 Cr 21 – 45 Sc 24 (I π = 3/2 + ) and 45V22– 45Ti23 (I π = 3/2 − ) are discussed in the framework of large scale

Core-coupled states and split proton-neutron quasiparticle multiplets in 122-126Ag

Neutron-rich silver isotopes were populated in the fragmentation of a Xe-136 beam and the relativistic fission of U-238. The fragments were mass analyzed with the GSI Fragment Separator and subsequently implanted into a passive stopper. Isomeric transitions were detected by 105 high-purity germanium detectors. Eight isomeric states were observed in Ag122-126 nuclei. The level schemes of Ag-122,Ag-123,Ag-125 were revised and extended with isomeric transitions being observed for the first time. The excited states in the odd-mass silver isotopes are interpreted as core-coupled states. The isomeric states in the even-mass silver isotopes are discussed in the framework of the proton-neutron split multiplets. The results of shell-model calculations, performed for the most neutron-rich silver nuclei are compared to the experimental data. DOI: 10.1103/PhysRevC.87.034308 (Less)

First results from the stopped RISING campaign at GSI: The mapping of isomeric decays in highly exotic nuclei

The first results from the Stopped Beam RISING experimental campaign performed at the GSI laboratory in Darmstadt, Germany, are presented. RISING (Rare ISotope INvestigations at GSI) constitutes a major new experimental program in European nuclear structure physics research aimed at using relativistic‐energy, projectile‐fragmentation reactions to study nuclei with exotic proton‐to‐neutron ratios. This paper introduces the physics aims of the Stopped RISING collaboration and presents some technical details and initial results from experiments using the RISING array to study decays from metastable nuclear states in both proton and neutron‐rich nuclei.

Relativistic coulomb excitation of neutron-rich 54,56,58Cr

The first excited 2+ states in neutron-rich 54,56,58Cr were populated by relativistic Coulomb excitation and B (E2, 2 1 + → 0+) values were determined for 56Cr and 58Cr. The B(E2) values show a minimum for 56Cr providing evidence for a subshell closure at N=32.

Single-particle isomeric states in 121Pd and 117Ru

Neutron-rich nuclei were populated in a relativistic fission of 238U. Gamma-rays with energies of 135 keV and 184 keV were associated with two isomeric states in 121Pd and 117Ru. Half-lives of 0.63(5) μs and 2.0(3) μs were deduced and the isomeric states were interpreted in terms of prolate deformed single-particle states.

Nuclear structure far off stability – New results from RISING

A broad range of physics phenomena can be addressed by high-resolution in-beam γ-ray spectroscopy experiments with radioactive beams offered within the Rare ISotopes INvestigation at GSI (RISING) project. It combines the EUROBALL Ge-Cluster detectors, the MINIBALL Ge detectors, the HECTOR-BaF detectors, and the fragment separator FRS. The secondary beams produced at relativistic energies are used for Coulomb excitation or secondary fragmentation experiments to study projectile like nuclei far off the stability line by measuring de-excitation photons. The physics studied comprises the evolution of shell structure towards the drip lines and its signatures as inferred from excitation energies, mirror symmetry and electromagnetic transition strengths. The first results of the fast beam campaign are discussed in comparison to various shell model calculations including the structure of light Sn isotopes based on Coulomb excitation of 108Sn, the discussion of the N = 32,34 sub-shell closure based on neutron-rich 56,58Cr isotopes, and the shell structure in light proton-rich Ca isotopes from the fragmentation of a 37Ca radioactive beam.