[en] The one-nucleon removal reactions from loosely bound carbon isotopes have been studied at FRS, GSI, using beam energies around 920 MeV/u. In particular, the longitudinal momentum distributions have been investigated, but cross sections have also been extracted

[en] Low-lying resonance states in ⁷He (⁶He + n), formed after fragmentation reactions of a 227 MeV/u ⁸He beam in a carbon target, have been studied. Coincidences between ⁶He nuclei and neutrons, corresponding to the one-neutron knockout channel in ⁸He, were selected. The relative energy spectrum in the ⁶He + n system shows a structure, which is interpreted as the ⁷He (I^π = 3/2^-) ground state, unbound with 0.43(2) MeV relative to the ⁶He + n system and a width of Γ = 0.15(8) MeV overlapping with an excited (I^π = 1/2^-) state observed at 1.0(1) MeV with a width of Γ = 0.75(8) MeV. (orig.)

[en] Dissociation of 227 MeV/u ⁸He in a carbon target has been studied in kinematically complete experiments. The data include the relative energy spectrum, angular distributions in the neutron knock-out channel (⁶He+n) as well as diffractive dissociation and inelastic scattering into the (⁶He+2n) channel. The data are compared with corresponding results from the well-known halo nucleus ⁶He. In both cases it is found that neutron knock-out is the dominating reaction channel. The relative energy spectrum (⁶He+n) shows a structure, which is interpreted as being due to the I^π=3/2^- resonance in the ⁷He ground state with about equal contribution from its I^π=1/2^- spin-orbit partner. The ⁷He resonance shows a spin alignment similar to that observed in ⁵He, but with a smaller anisotropy indicating that the structure of the ⁸He ground state is more complicated than that of ⁶He. The data in the (⁶He+2n) channel were used to identify resonances in the excitation energy spectrum of ⁸He. If the spectrum is interpreted as two overlapping resonances, the spin-parity assignment for these is found to be 2⁺ and 1^-, respectively. (orig.)

[en] Low-lying resonance states in ⁷He (⁶He + n), formed after fragmentation reactions of a 227 MeV/u ⁸He beam in a carbon target, have been studied. Coincidences between ⁶He nuclei and neutrons, corresponding to the one-neutron knockout channel in ⁸He, were selected. The relative energy spectrum in the ⁶He + n system shows a structure, which is interpreted as the ⁷He (I^π = 3/2^-) ground state, unbound with 0.43(2) MeV relative to the ⁶He + n system and a width of Γ = 0.15(8) MeV overlapping with an excited (I^π = 1/2^-) state observed at 1.0(1) MeV with a width of Γ = 0.75(8) MeV. (orig.)

[en] In a search for β-delayed charged particles from ¹⁴Be we have obtained an upper limit on β-delayed α particles, B(βα)<1.2x10^-4, and found evidence for β-delayed tritons at intensity of 6x10^-5< B(βt)<4x10^-4 (both at 95% confidence level). By adding information on the β-delayed neutron branches from direct measurements at low neutron energy and indirect detection via recoiling nuclei at high energy, and by including also information from earlier experiments, we deduce the β strength distribution from ¹⁴Be. This differs significantly from shell-model calculations at high excitation energy

[en] Dissociation of a 227 MeV/u ⁸He beam in a lead target has been studied in a kinematically complete experiment. The results are compared with similar data from the well-known halo nucleus ⁶He. Coulomb-nuclear interference in the inelastic channel gives evidence for a I^π = 1^- resonance in ⁸He at E_x=4.15 MeV. The deduced B(E1) value of 0.38±0.07 e²fm² indicates a uniform distribution of the four neutrons around the α particle core. (orig.)

[en] In this contribution examples of the application of new technologies to disentangle the mechanism of beta-delayed multiparticle emission are given. In particular the mechanism of β-delayed two-proton emission from ³¹Ar has been resolved and proved to be sequential, a preview of ⁹C-decay data is discussed

[en] Complete text of publication follows. The fragment separator FRS was used as an energy-loss spectrometer to measure longitudinal momentum distributions of fragments after one-nucleon removal reactions for different secondary beams at relativistic energies. The one-nucleon removal and total-interaction cross-sections of these secondary beams were also measured with the same experimental setup. In the past, a narrow momentum distribution of the fragments and a large interaction cross-section were considered as a clear signature of a halo. From the study of heavier systems we have learned that the information obtained from the one-nucleon removal cross-sections in addition, is necessary to test theoretical predictions describing the nuclear structure of halo nuclei from different models. With this technique only inclusive measurements were possible, no direct experimental evidence of the mixture of configurations for the halo nuclei in its ground state was given. The upgrade of our experimental setup has allowed us to detected gamma rays around the one-nucleon removal target in coincidence with the longitudinal momentum distributions and removal cross sections. This technique, one of the few examples of in-beam spectroscopy at relativistic energies, combined with secondary nuclear reaction has added new information that will allow us to better understand the nature of halo nuclei by means of exclusive measurements. During this talk, experimental results on momentum distributions, one-nucleon removal and interaction cross-sections for several C, B, and O isotopes will be presented, in coincidence with gamma ray detection. The isotopes studied range from tightly bound nuclei to neutron-rich (¹⁹C,²⁴O) or proton-rich (⁸B,⁹C) halo candidates and they will be compared with theoretical calculations. (author)

[en] In β-decay experiments on ⁹C at CERN/ISOLDE the β-strength was determined to the ground state, the 12.2 MeV excited state and the Isobaric Analog State (IAS) at 14.655 MeV in ⁹B. A large β-strength asymmetry is deduced for the mirror transitions of ⁹C and ⁹Li to states around 12 MeV excitation energy. A satisfactory description of the three-body decay from a narrow energy region around the 12.2 MeV resonance is obtained within a sequential model involving the ground and first-excited states of ⁵Li and ⁸Be. From the study of angular correlations the spin of the 12.2 MeV state is determined as 5/2^-. For the first time the population of the IAS is observed in β-decay and new information on the decay of this state is obtained. The advantages of a closely packed, highly segmented detector setup are demonstrated

[en] The β-delayed neutron branches from neutron-rich Be-isotopes have been measured with a setup sensitive down to thermal energies. For ¹⁴Be a new value of P_n = 101 ± 4% has been found for the total neutron-emission probability and an upper limit of 2.4% (95% confidence level) is imposed on the combination P_2n + 3P_3n of multi-neutron emission probabilities. Moreover, an improved value of P_n = 0.50 ± 0.03% has been obtained for ¹²Be. A time-correlation method, previously developed for a continuous radioactive beam to determine neutron branching ratios, has been revised and adapted to the pulsed secondary beam at ISOLDE, CERN