Intense beams of radioactive halogens produced by means of surface ionization

Vosicki, B.; Björnstad, T.; Carraz, L.C.; Heinemeier, Jan; Ravn, H.L.

doi:10.1016/0029-554x(81)90918-6

Cited by 89 publications

(29 citation statements)

References 19 publications

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“…In previous half-life measurements, 70 Br nuclei were produced in fragmentation and fusion-evaporation reactions [37][38][39][40], which are optimal tools for the population of isomeric states. Though the T = 0 (J π = 9 + ) β-decaying isomer was already known by the time most of these works were published [41], its contribution to the measured decay curve has hitherto been neglected. Therefore, this is the first work in which both the T = 1 (J π = 0 + ) and T = 0 (J π = 9 + ) β decays of 70 Br were investigated simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

Morales¹,

Algora²,

Rubio³

et al. 2017

Phys. Rev. C

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Simultaneous investigation of the T = 1 (J π = 0 + ) and T = 0 (J π = 9 + ) β decays in The β decay of the odd-odd nucleus 70 Br has been investigated with the BigRIPS and EURICA setups at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center. The T = 0 (J π = 9 + ) and T = 1 (J π = 0 + ) isomers have both been produced in in-flight fragmentation of 78 Kr with ratios of 41.6(8)% and 58.4(8)%, respectively. A half-life of t 1/2 = 2157 +53 −49 ms has been measured for the J π = 9 + isomer from γ-ray time decay analysis. Based on this result, we provide a new value of the half-life for the J π = 0 + ground state of 70 Br, t 1/2 = 78.42 ± 0.51 ms, which is slightly more precise, and in excellent agreement, with the best measurement reported hitherto in the literature. For this decay, we provide the first estimate of the total branching fraction decaying through the 2 + 1 state in the daughter nucleus 70 Se, R(2 + 1 ) = 1.3 ± 1.1%. We also report four new low-intensity γ-ray transitions at 661, 1103, 1561, and 1749 keV following the β decay of the J π = 9 + isomer. Based on their coincidence relationships, we tentatively propose two new excited states at 3945 and 4752 keV in 70 Se with most probable spins and parities of J π = (6 + ) and (8 + ), respectively. The observed structure is interpreted with the help of shell-model calculations, which predict a complex interplay between oblate and prolate configurations at low excitation energies.

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Section: Introductionmentioning

confidence: 99%

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

Morales¹,

Algora²,

Rubio³

et al. 2017

Phys. Rev. C

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“…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.…”

mentioning

confidence: 99%

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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“…The successful negative ionization method developed at ISOLDE has been described in detail by Vosicki et al [1]. The negative ionization occurs on a LaB 6 surface kept at a temperature of about 1,100 ~ On this surface, the ionization efficiency for halogens is close to 100~.…”

Section: The Ionizermentioning

confidence: 98%

“…At the CERN-ISOLDE on-line mass separator, it has been demonstrated that the high electron affinities of the halogens allow the use of negative surface ionization for production of intense and selective ion beams of chlorine and bromine [1]. In the early experiments, where UC-graphite targets were used in conjunction with a LaB 6 surface-ionization source, a deterioration as a function of time of operation was observed.…”

Section: Introductionmentioning

confidence: 96%

Intense mass-separated beams of halogens and beta-delayed neutron emission from heavy bromine isotopes

et al. 1984

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Improved production yields of short-lived halogens were obtained from a ThO 2 target, irradiated with 600 MeV protons, in combination with a negative surface ionization source. Mass-separated samples were studied by decay spectroscopy. Production yields of radioactive isotopes of chlorine, bromine, iodine and astatine are presented. Halflives and relative neutron emission probabilities were measured for the heavy bromine isotopes 89-9ZBr. Normalizing to earlier published P, values for 89Br, the results are' S9Br (4.30_0.14s, P,=13.6_+0.8~), 9~(1.92_+0.06s, P,=24.8__1.5~), 91Br (0.53 ___ 0.03 s, P, = 30.1 _+ 2.1 ~), and 92Br (0.31 ___ 0.02 s, P, = 34.6_+ 2.5 ~). Energy spectra of/~-delayed neutrons were measured.

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Intense beams of radioactive halogens produced by means of surface ionization

Cited by 89 publications

References 19 publications

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

Simultaneous investigation of the T=1(Jπ=0+) and T=0(J

Onset of deformation in neutron-rich krypton isotopes

Intense mass-separated beams of halogens and beta-delayed neutron emission from heavy bromine isotopes

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