Excited states in Br87 populated in β decay of Se87

Penning-trap-assisted study of excitations in Br88 populated in β decay of Se88

Excited levels of $^{88}\mathrm{Br}$ populated in the $\ensuremath{\beta}$ decay of $^{88}\mathrm{Se}$ have been studied by means of $\ensuremath{\beta}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{\gamma}$ spectroscopy methods. Neutron-rich parent $^{88}\mathrm{Se}$ nuclei were produced with proton-induced fission of $^{238}\mathrm{U}$ using the Ion Guide Isotope Separator On-Line (IGISOL) method and separated from contaminants using a dipole magnet and the coupled JYFLTRAP Penning trap at the Accelerator Laboratory of the University of Jyv\"askyl\"a. The level scheme of $^{88}\mathrm{Br}$ has been constructed and $logft$ values of levels were determined. The ground-state spin o…

Signatures of oblate deformation in the ^{111}Tc nucleus

Monoisotopic samples of exotic, neutron-rich ${}^{111}$Mo nuclei, produced in the deuteron-induced fission of ${}^{238}$U and separated using the IGISOL3 isotope separator, coupled to the JYFLTRAP Penning trap, were used to perform $\ensuremath{\beta}$- and $\ensuremath{\gamma}$-coincidence spectroscopy of ${}^{111}$Tc. New excited levels in ${}^{111}$Tc populated in ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of ${}^{111}$Mo provide the first indication for an oblate deformation in the mass $A\ensuremath{\approx}110$ region. The wide spin range of levels populated in ${}^{111}$Tc following the decay of ${}^{111}$Mo indicates the existence of two $\ensuremath{\beta}$-decaying levels in ${…

β - and γ -spectroscopy study of Pd119 and Ag119

Neutron configurations in 113Pd

Excited states in 113Pd, populated in β− decay of 113Rh and in spontaneous fission of 248Cm and 252Cf, have been studied by means of γ spectroscopy at the IGISOL facility of Jyvaskylä University and using large arrays of Ge detectors (Eurogam2 and Gammasphere, respectively). The position of the 11/2− yrast excitation in 113Pd, proposed recently at 166.1 keV by other authors, has been corrected to 98.9 keV. The decay of this level has been discussed to explain the observed transition intensities. The 7/2− member of the yrast, unique-parity configuration has been identified at 84.9 keV and a band on top of this level proposed. On top of the 1/2+, first excited state a band has been built and …

Low-spin excitations in the 109Tc nucleus

Monoisotopic samples of ${}^{109}$Mo nuclei, produced in the deuteron-induced fission of ${}^{238}$U and separated using the IGISOL mass separator coupled to a Penning trap, were used to perform $\ensuremath{\beta}$- and $\ensuremath{\gamma}$-coincidence spectroscopy of ${}^{109}$Tc. Spin and parity 5/2${}^{+}$ for the ground state of ${}^{109}$Mo, proposed earlier, are supported in the present work. Three new low-energy levels observed in ${}^{109}$Tc are interpreted as bandheads of the $\ensuremath{\pi}3/{2}^{\ensuremath{-}}$[301], $\ensuremath{\pi}5/{2}^{\ensuremath{-}}$[303], and $\ensuremath{\pi}1/{2}^{+}$[431] configurations, respectively. A further three levels observed around 0.4 Me…

Low-spin excitations in 89Br populated in β−decay of 89Se

Low-spin, excited states of the 89Br nucleus, populated in β− decay of 89Se have been studied for the first time. The 89Se nuclei were produced in proton-induced fission of natural thorium using the IGISOL facility and separated using a dipole magnet and the coupled JYFLTRAP Penning trap. Gamma radiation following the β− decay of 89Se was measured with an array of high-resolution germanium detectors. Levels scheme of 89Br was extended by 12 new levels and 31 new γ transitions. Spin-parity (3/2+) has been proposed for the ground state of the 89Se mother nucleus, replacing the (5/2+) assignment reported in data bases. The observed Gamow-Teller β− transition to the 1754.5-keV level indicates a…

Long survival time of an isolated perfused rat brain

Structure of 115Ag studied by β− decays of 115Pd and 115mPd

The excited levels of 115Ag have been studied via the beta decay of 115Pd and 115Pdm. The beta-decay schemes for both states have been considerably extended, especially the scheme following the decay of 115Pdm which was practically unknown before this work. Transition intensities and log10 f t values are reported, which have been missing in the literature. A set of levels around 2 MeV has been found to be strongly populated by the beta decay of the ground state of 115Pd and is suggested to have a three-quasiparticle nature. The properties of excited levels have been compared with the level systematics of lighter neutron-rich silver isotopes, and new spin assignments as well as identificatio…

Structure of115Ag studied byβ−decays of115Pd and115Pdm

The excited levels of ${}^{115}$Ag have been studied via the beta decay of ${}^{115}$Pd and ${}^{115}$Pd${}^{m}$. The beta-decay schemes for both states have been considerably extended, especially the scheme following the decay of ${}^{115}$Pd${}^{m}$ which was practically unknown before this work. Transition intensities and ${\mathrm{log}}_{10}ft$ values are reported, which have been missing in the literature. A set of levels around 2 MeV has been found to be strongly populated by the beta decay of the ground state of ${}^{115}$Pd and is suggested to have a three-quasiparticle nature. The properties of excited levels have been compared with the level systematics of lighter neutron-rich sil…

Excited levels in the multishaped 117Pd nucleus studied via β decay of 117Rh

Monoisotopic samples of exotic, neutron-rich 117Rh nuclei, produced in the proton-induced fission of 238U and separated using the IGISOL mass separator coupled to the JYFLTRAP Penning trap, were used to perform β and γ coincidence spectroscopy of 117Pd. The spin parity of the ground state of 117Pd was determined to be 1/2+ and the 19.1 ms isomer at 203.2 keV was assigned a spin-parity 7/2−. The 117Rh β−-decay scheme was considerably extended, and various sequences of the levels were interpreted as resulting from the prolate, oblate, and triaxial nuclear shapes. Some of the β− decays were considered as the allowed Gamow-Teller transitions. The experimental distribution of Gamow-Teller streng…

β- and γ-spectroscopy study of 119Pd and 119Ag

Neutron-rich 119Pd nuclei were produced in fission of natural uranium, induced by 25-MeV protons. Fission fragments swiftly extracted with the Ion Guide Isotope Separation On-Line method were mass separated using a dipole magnet and a Penning trap, providing mono-isotopic samples of 119Pd. Their β− decay was measured with γγ- and βγ-spectroscopy methods using low-energy germanium detectors and a thin plastic scintillator. Two distinct nuclear-level structures were observed in 119Ag, based on the 1/2− and 7/2+ isomers reported previously. The β−-decay work was complemented by a prompt-γ study of levels in 119Ag populated in spontaneous fission of 252Cf, performed using the Gammasphere array …

Trap-assisted studies of odd, neutron-rich isotopes from Tc to Pd

We review the present and future of trap-assisted structure studies of odd, neutron-rich Tc, Ru, Rh and Pd isotopes at the limits of present experimental techniques. These nuclei of refractory elements are produced in light-particle induced fission and filtered by their mass number with the IGISOL mass separator. Further mass separation with the JYFLTRAP Penning trap system provides a clean, monoisotopic beam perfectly suited for precise nuclear spectroscopy. Connecting the IGISOL and the JYFLTRAP facilities to the recently installed MCC30/15 cyclotron opens new prospects for post-trap spectroscopy of very exotic, neutron-rich nuclei. peerReviewed

Penning-trap-assisted study of 115Ru beta decay

The beta decay of 115Ru has been studied by means of Penning-trap-assisted beta and gamma spectroscopy at the IGISOL facility. The level scheme of 115Rh has been substantially extended and compared with the level systematics of lighter rhodium isotopes. Tentative candidates for three states of the deformed K = 1/2 band have been suggested. The beta-strength distribution of the beta decay of 115Ru differs from the beta decays of 111, 113, 113mRu isotopes due to non-observation of the 3-quasiparticle states in 115Rh. The decay properties of 115Ru indicate a spin-parity of (3/2+ for its beta-decaying ground state. In addition, possible Nilsson states as well as the shape and spin transitions i…

Penning-trap-assisted study of excitations in $^{88}$Br populated in β decay of $^{88}$Se

Excited levels of 88Br populated in the β decay of 88Se have been studied by means of βγ and γ γ spectroscopy methods. Neutron-rich parent 88Se nuclei were produced with proton-induced fission of 238U using the Ion Guide Isotope Separator On-Line (IGISOL) method and separated from contaminants using a dipole magnet and the coupled JYFLTRAP Penning trap at the Accelerator Laboratory of the University of Jyvaskyl ¨ a. The level scheme ¨ of 88Br has been constructed and log f t values of levels were determined. The ground-state spin of 88Br is now firmly determined to be 1−. Low-energy levels in 88Br were interpreted as members of the πp3/2(νd5/2) 3, πp−1 3/2(νd5/2) 3, πf −1 5/2 (νd5/2) 3, and…

Low-spin structure of85Se and theβnbranching of85As

Fission fragments from neutron-induced fission of ${}^{235}$U produced at the high-flux reactor of the Institut Laue-Langevin, Grenoble, were separated with the Lohengrin separator to provide a beam of neutron-rich ${}^{85}\phantom{\rule{-0.16em}{0ex}}$As nuclei. The ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of ${}^{85}\phantom{\rule{-0.16em}{0ex}}$As to ${}^{85}$Se was studied using $\ensuremath{\gamma}$-$\ensuremath{\gamma}$ and $\ensuremath{\beta}$-$\ensuremath{\gamma}$ coincidence techniques. ${}^{85}$Se was also studied using the prompt-$\ensuremath{\gamma}$ coincidence data from spontaneous fission of ${}^{248}$Cm and ${}^{252}$Cf measured with the Eurogam2 and Gammasphere Ge arra…

Excited states inPd115populated in theβ−decay ofRh115

Excited states in $^{115}\mathrm{Pd}$, populated following the ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{115}\mathrm{Rh}$ have been studied by means of $\ensuremath{\gamma}$ spectroscopy after the Penning-trap station at the IGISOL facility, University of Jyv\"askyl\"a. The $1$$/$$2$${}^{+}$ spin and parity assignment of the ground state of $^{115}\mathrm{Pd}$, confirmed in this work, may indicate a transition to an oblate shape in Pd isotopes at high neutron number.

Shape coexistence in the odd-odd nucleus 98Y : the role of the g9/2 neutron extruder

Excited states in 98Y, populated in neutron-induced fission of 235U and in spontaneous fission of 248Cm and 252Cf, have been studied by means of γ spectroscopy using the Lohengrin fission-fragment separator at ILL Grenoble and the EXILL, Eurogam2, and Gammasphere Ge arrays. Two new isomers have been found in 98Y: a deformed one with T1/2 = 180(7) ns and a rotational band on top of it, and a spherical one with T1/2 = 0.45(15)μs, analogous to the 8+ isomer in 96Y, corresponding to the (νg7/2,πg9/2)8+ spherical configuration. Using the JYFLTRAP Penning trap, an accurate excitation energy of 465.7(7) keV has been determined for the 2.36-s isomer in 98Y. This result and the studies of excited le…

Decay study ofTc114with a Penning trap

The level structure of $^{114}\mathrm{Ru}$ has been investigated via the $\ensuremath{\beta}$ decay of very neutron-rich $^{114}\mathrm{Tc}$ by means of Penning-trap-assisted $\ensuremath{\gamma}$ spectroscopy. The deduced $\ensuremath{\beta}$-decay scheme suggests the existence of two $\ensuremath{\beta}$-decaying states in $^{114}\mathrm{Tc}$ with ${I}^{\ensuremath{\pi}}={1}^{+}$ and $I\ensuremath{\geqslant}$ 4, with half-lives of ${t}_{1/2}({1}^{+})=90(20)$ ms and ${t}_{1/2}(I\ensuremath{\geqslant}4)=100(20)$ ms, respectively. The ${Q}_{\ensuremath{\beta}}$ value, which covers a possible mixture of two states, has been determined to be ${Q}_{\ensuremath{\beta}}=11 785(12)$ keV. The level…

First β -decay scheme of Nb107 : New insight into the low-energy levels of Mo107

Monoisotopic samples of $^{107}\mathrm{Nb}$ nuclei, produced in the proton-induced fission of $^{238}\mathrm{U}$ and separated using the IGISOL mass separator coupled to a Penning trap, were used to perform $\ensuremath{\beta}$- and $\ensuremath{\gamma}$-coincidence spectroscopy of $^{107}\mathrm{Mo}$. Gamma transitions and excited levels in $^{107}\mathrm{Mo}$ were observed in $\ensuremath{\beta}$ decay for the first time. Spin and parity $1/{2}^{+}$ for the ground state of $^{107}\mathrm{Mo}$ is proposed, to replace the previous $5/{2}^{+}$ assignment. The experimental $\ensuremath{\beta}$-decay half-life of $^{107}\mathrm{Nb}$ was estimated to be $0.27\ifmmode\pm\else\textpm\fi{}0.02$ s.

Levels of 188Re nucleus populated in thermal neutron capture reaction

Abstract Levels of 188 Re populated in thermal neutron capture reaction with enriched 187 Re targets have been studied. Single γ -ray spectrum of 188 Re, measured with the high-resolution crystal diffraction spectrometer GAMS5, as well as γγ -coincidence experiments performed with high efficiency Ge detectors, allowed to develop model-independent level scheme of the doubly-odd 188 Re nucleus up to ∼ 1.5 MeV excitation energy. Analysis of the established 188 Re level scheme in terms of the quasiparticle-plus-rotor model indicates coexistence of axially-deformed and triaxial structures in the energy range above 400 keV.

Excited states in 87Br populated in β decay of 87Se

Excited levels in 87Br, populated in β decay of 87Se, have been studied by means of γ-ray spectroscopy using an array of broad energy Ge detectors. 87Se nuclei were produced by irradiating a natural Th target with 25-MeV protons. Fission products were extracted from the target chamber using the IGISOL technique, then separated on a dipole magnet and Penning trap (JYFLTRAP) setup. The scheme of excited levels of 87Br has been significantly extended. 114 new transitions and 51 new levels were established. β feedings and log(ft) values of levels were determined. The upper limit for β feeding to the ground state of 87Br was determined to be 23(5)%. Ground state spin and parity 5/2− was confirme…

Excited levels in the multishaped Pd117 nucleus studied via β decay of Rh117

Monoisotopic samples of exotic, neutron-rich $^{117}\mathrm{Rh}$ nuclei, produced in the proton-induced fission of $^{238}\mathrm{U}$ and separated using the IGISOL mass separator coupled to the JYFLTRAP Penning trap, were used to perform $\ensuremath{\beta}$ and $\ensuremath{\gamma}$ coincidence spectroscopy of $^{117}\mathrm{Pd}$. The spin parity of the ground state of $^{117}\mathrm{Pd}$ was determined to be $1/{2}^{+}$ and the 19.1 ms isomer at 203.2 keV was assigned a spin-parity $7/{2}^{\ensuremath{-}}$. The $^{117}\mathrm{Rh}$ ${\ensuremath{\beta}}^{\ensuremath{-}}$-decay scheme was considerably extended, and various sequences of the levels were interpreted as resulting from the prol…

Levels of 186Re populated in thermal neutron capture reaction

Levels of 186 Re have been studied in the thermal neutron capture reaction with an enriched 185 Re target. Evaluation of spectrum measured with GAMS5 allowed to obtain energies and intensities of more than 500 γ -lines assigned to 186 Re. Most of the obtained transitions have been placed in the model-independent level scheme of the doubly odd 186 Re nucleus, taking into account the available data of earlier experiments as well as the results of recent 187 Re(p, d )186 Re reaction measurements. Structure of the 186 Re low-lying levels has been analysed in terms of the particle-plus-rotor coupling model.

Neutron configurations inPd113

Excited states in $^{113}\mathrm{Pd}$, populated in ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{113}\mathrm{Rh}$ and in spontaneous fission of $^{248}\mathrm{Cm}$ and $^{252}\mathrm{Cf}$, have been studied by means of $\ensuremath{\gamma}$ spectroscopy at the IGISOL facility of Jyv\"askyl\"a University and using large arrays of Ge detectors (Eurogam2 and Gammasphere, respectively). The position of the ${11/2}^{\ensuremath{-}}$ yrast excitation in $^{113}\mathrm{Pd}$, proposed recently at 166.1 keV by other authors, has been corrected to 98.9 keV. The decay of this level has been discussed to explain the observed transition intensities. The ${7/2}^{\ensuremath{-}}$ member of the yras…

First β-decay scheme of 107Nb : New insight into the low-energy levels of 107Mo

Monoisotopic samples of 107Nb nuclei, produced in the proton-induced fission of 238U and separated using the IGISOL mass separator coupled to a Penning trap, were used to perform β- and γ-coincidence spectroscopy of 107Mo. Gamma transitions and excited levels in 107Mo were observed in β decay for the first time. Spin and parity 1/2+ for the ground state of 107Mo is proposed, to replace the previous 5/2+ assignment. The experimental β-decay half-life of 107Nb was estimated to be 0.27±0.02 s. peerReviewed

β - and γ -spectroscopy study of Pd 119 and Ag 119

New isomer and decay half-life ofRu115

Exotic, neutron-rich nuclei of mass $A=115$ produced in proton-induced fission of $^{238}\mathrm{U}$ were extracted using the IGISOL mass separator. The beam of isobars was transferred to the JYFLTRAP Penning trap system for further separation to the isotopic level. Monoisotopic samples of $^{115}\mathrm{Ru}$ nuclei were used for $\ensuremath{\gamma}$and $\ensuremath{\beta}$ coincidence spectroscopy. In $^{115}\mathrm{Ru}$ we have observed excited levels, including an isomer with a half-life of 76(6) ms and ($7/{2}^{\ensuremath{-}}$) spin and parity. The first excited 61.7-keV level in $^{115}\mathrm{Ru}$ with spins and parity ($3/{2}^{+}$) may correspond to an $\mathit{oblate}$ $3/{2}^{+}$…