Search results for "Coulomb [force]"
showing 10 items of 103 documents
Low-lying levels of201Hg from the decay of201Au
1972
The decay of 26.4-min201Au has been investigated using chemically separated sources and Ge(Li), Si(Li), plastic and Nal(Tl) detectors in different singles and coincidence arrangements. The β-disintegration energy was measured to be 1.27 ± 0.10 MeV. Thirteen γ-rays were observed to belong to this decay and the new levels at 543, 549.2, 552.8, 559.1, 605.7, 645.4, 732 and 1188 keV were established in201Hg, in addition to the three previously known excited states below 200 keV.
"Safe" Coulomb excitation of 30Mg.
2004
We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient $\gamma$ -spectrometer MINIBALL. Using $^{30}$Mg ions accelerated to an energy of 2.25MeV/u together with a thin $^{nat}$Ni 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 de-excitation $\gamma$ -ray yields the B(E2; 0$^{+}_{gs} \rightarrow 2^{+}_{1}$) value of $^{30}$Mg was determined to be 241(31)$e^{2}$fm$^{4}$. Our result is lower than values obtained at projectile fragmenttion facilities using the intermediate-ene…
High-Statistics Sub-Barrier Coulomb Excitation of $^{106,108,110}$Sn
2020
International audience; A Coulomb excitation campaign on $^{106,108,110}$Sn at 4.4–4.5 MeV/u was launched at the HIE-ISOLDE facility at CERN. Larger excitation cross sections and γ-ray statistics were achieved compared to previous experiments at ∼2.8 MeV/u. More precise $(B(E2;0_{1}^{ + } \to 2_{1}^{ + }))$ values, lifetimes of states via the Doppler shift attenuation method, and new $(B(E2;0_{1}^{ + } \to 2_{x}^{ + })), (B(E2;2_{1}^{ + } \to 4_{1}^{ + }))$ and $(Q(2_{1}^{ + }))$ values from the new Miniball data will be obtained and applied to test modern nuclear structure theories.
Evolution of quadrupole collectivity in N=80 isotones toward the Z=64 subshell gap: The B(E2;2+1→0+1) value of 142Sm
2015
It was shown that the evolution of the B(E2; 2+ 1 → 0+ 1 ) values in N = 80 isotones from Te to Nd is affected by the underlying subshell structure. This manifests itself in the observation of the local suppression of the B(E2) value at Z = 58 with respect to the neighboring nuclei 136Ba and 140Nd. To investigate this shell sensitivity toward the Z = 64 subshell gap, the B(E2; 2+ 1 → 0+ 1 ) value of the unstable nucleus 142Sm was measured utilizing the projectile Coulomb excitation technique. The radioactive ion beam (RIB) experiment was performed at the REX-ISOLDE facility at CERN. The B(E2) value of 32 (4) W.u. reflects the impact of the π(1g7/2 2d5/2) subshell closure at Z = 64 with resp…
Three-body correlations in electromagnetic dissociation of Borromean nuclei: The 6He case
2005
20 pages, 2 tables, 9 figures, 1 appendix.-- PACS nrs.: 25.60.-t; 27.20.+n; 25.70.De; 25.75.Gz.-- Printed version published Sep 5, 2005.
New developments on the recoil distance doppler-shift method
2010
Absolute transition probabilities are fundamental observables for nuclear structure. The recoil-distance-Doppler-shift (RDDS) technique, also called plunger technique, is a well established tool for the determination of these important experimental quantities via the measurement of lifetimes of excited nuclear states. Nowadays nuclear structure investigations are concentrated on exotic nuclei which are often produced with extremely small cross sections or with very low beam intensities. In order to use the RDDS technique also for the investigation of very exotic nuclei this method has to be adapted to the specific needs of these special reactions. This article gives an overview on recent RD…
Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes
2015
Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po196,198,200,202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po200,202, the transitional and diagonal matrix elements of the 2+1 state are determined. In Po196,198 multistep Coulomb excitation is observed, populating the 4+1,0+2, and 2+2 states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from Po196 onwards. Three model descriptions are used to compare to the data. Calculati…
Structure of low-lying states in 140Sm studied by Coulomb excitation
2016
The electromagnetic structure of 140Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The 2+ and 4+ states of the ground-state band and a second 2+ state were populated by multistep excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the 2+ 1 state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and alge…
The REX-ISOLDE project
1998
Abstract REX-ISOLDE [1] is an experiment at ISOLDE/CERN with a twofold aim: (i) to demonstrate a novel efficient scheme for the acceleration of radioactive ions from the online mass separator ISOLDE to energies around the Coulomb barrier. (ii) to perform first nuclear physics experiments by studying the structure of the neutron-rich (N = 20, N = 28) nuclei by Coulomb excitation and neutron transfer reactions. An overview on the different components of the radioactive beam accelerator is given with special emphasis on the separation possibilities and ion number capabilities of the system.
Development of a new Recoil Distance Technique using Coulomb Excitation in Inverse Kinematics
2009
We report on an experiment using Coulomb excitation in inverse kinematics in combination with the plunger technique for measuring lifetimes of excited states of the projectiles. Aside from the investigation of E(5) features in 128Xe, the aim was to explore the special features of such experiments which are also suited to be used with radioactive beams. The measurement was performed at the JYFL with the Koln coincidence plunger device and the JUROGAM spectrometer using a 128Xe beam impinging on a natFe target at a beam energy of 525 MeV. Recoils were detected by means of 32 solar cells placed at extreme forward angles. Particle‐gated γ‐singles and γγ‐coincidences were measured at different t…