A negative surface-ionization ion source for the on-line mass separator OSTIS

Rabbel, V.; Stoehlker, U.; Muenzel, J.; Wöllnik, H.; Bloennigen, F.; Kobras, K.; Lippert, W.

doi:10.1016/0168-583x(87)90758-0

Cited by 3 publications

(1 citation statement)

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“…The ion source was equipped with a planar sintered porous LaB 6 ionizer and demonstrated 10%-50% ionization efficiencies for Cl, Br, I and At. A similar LaB 6 ionizer configuration was employed in a source to provide halogen isotopes for nuclear spectroscopy at the on-line mass separator OSTIS [25]. The early experiments at ISOLDE revealed that the LaB 6 ionizer was susceptible to poisoning when it was used with inappropriate target materials decomposing at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Production of negatively charged radioactive ion beams

2017

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Beams of short-lived radioactive nuclei are needed for frontier experimental research in nuclear structure, reactions, and astrophysics. Negatively charged radioactive ion beams have unique advantages and allow for the use of a tandem accelerator for post-acceleration, which can provide the highest beam quality and continuously variable energies. Negative ion beams can be obtained with high intensity and some unique beam purification techniques based on differences in electronegativity and chemical reactivity can be used to provide beams with high purity. This article describes the production of negative radioactive ion beams at the former holifield radioactive ion beam facility at Oak Ridge National Laboratory and at the CERN ISOLDE facility with emphasis on the development of the negative ion sources employed at these two facilities.

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Section: Introductionmentioning

confidence: 99%

Production of negatively charged radioactive ion beams

2017

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Onset of deformation in neutron-rich krypton isotopes

Kratz

Gabelmann

Pfeiffer

et al. 1988

Z. Physik A - Atomic Nuclei

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Beta-decay properties of neutron-rich 3=Br isotopes confirm the predicted smooth onset of quadrupole deformation for Z<37 already below N=60. The observed increase of the energy of the first 2 + state in the N=56 nucleus ~2Kr may indicate octupole softness.During the last decade, extensive studies have been devoted to the level structures of neutronrich nuclei around A=IO0.For ee-isotopes in this region, already the behaviour of the first 2 + levels (see Fig. i) indicates the well-known transition from spherical to deformed shapes as neutrons are added beyond N=58, with an extremely sharp transition for 4oZr and ~aSr (see, e.g. [1,2]). The suddeness of this transition has been interpreted as an effect of the spherical Z=40 shell gap which can locally reinforce the N=56 spherical gap (see the 2 + peak for ~Zr) to delay the shape transition until the Z=38, N=60 gaps at large deformation can reinforce each other. As the proton number moves away from 40, the influence of the spherical N=56 subshell should quickly disappear. While for the heavier elements (4zMo to 46Pd) the E(2+), indeed, decrease more gradually indicating a smooth onset of deformation, so far no experimental data were available for lighter elements (34Se, s6Kr) with N>54. The region around Z=36, N=56 is of particular interest because of the predicted octupole softness [2][3][4]. With the halogen beams available at the mass separators OSTIS (ILL-Grenoble) and ISOLDE (tERNGeneva), we have started a systematic investigation of ~-decay properties of heavy Br isotopes in order to check the above predictions for Z<37 nuclei. At both facilities UC-graphite targets were used which were connected to negative-surface ion sources with a Lab6 ionizer [5,6]. Spectroscopic information was obtained from multiscaling of delayed neutrons and B-particles to derive T~/2 and P~ values, and from Y-singles and YT-coincidence measurements to establish partial decay schemes. The most surprising result is the observation of an increase of E(2 +) in 92Kr by about 60 keV relative to ~~ indicating a gap at N=56 for Z=36 (see Fig. i). On the one hand, this increase appears small compared to the 830 keV in the double semi-magic 96Zr; on the other hand, however, the effect in 92Kr is remarkable when regarding the E(2 § trends in the isotones with Z=(40• and Z=(40+4). Already in 98Mo and ~4Sr the increase of the E(2 § has with 9 keV, respectively 22 keV become very small; and in the 4~Ru isotopes, one observes a decrease of the E(2 § by about ii0 keV when going from N=54 to 56. Based on this behaviour the effective N=56 gap in 92Kr has to be considered even stronger than the apparent increase of E(2+). One is now forced to question why a subshell gap exists in ~2Kr while it has more or less disappeared in the other N=56 isotones around 9~Zr. For the double semi-magic Q6Zr there is consistent interpretation that the spherical gaps in both the proton and neutron systems give a particularly low shell energy for the spherical shape [1,2]. With the proton shell structure domin...

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