Nuclear structure beyond the neutron drip line: the lowest energy states in $^9$He via their T=5/2 isobaric analogs in $^9$Li

E. Uberseder; G. V. Rogachev; V. Z. Goldberg; E. Koshchiy; B. T. Roeder; M. Alcorta; G. Chubarian; B. Davids; C. Fu; J. Hooker; H. Jayatissa; D. Melconian; R. E. Tribble

doi:10.1016/j.physletb.2016.01.014

arXiv · 1504.00879

Nuclear structure beyond the neutron drip line: the lowest energy states in $^9$He via their T=5/2 isobaric analogs in $^9$Li

E. Uberseder·G. V. Rogachev·V. Z. Goldberg·E. Koshchiy·B. T. Roeder·M. Alcorta·G. Chubarian·B. Davids·C. Fu·J. Hooker·H. Jayatissa·D. Melconian·R. E. Tribble

View original source ↗Read source document ↗Export metadata ↓

Abstract

The level structure of the very neutron rich and unbound $^9$He nucleus has been the subject of significant experimental and theoretical study. Many recent works have claimed that the two lowest energy $^9$He states exist with spins $J^π=1/2^+$ and $J^π=1/2^-$ and widths on the order of hundreds of keV. These findings cannot be reconciled with our contemporary understanding of nuclear structure. The present work is the first high-resolution study with low statistical uncertainty of the relevant excitation energy range in the $^8$He$+n$ system, performed via a search for the T=5/2 isobaric analog states in $^9$Li populated through $^8$He+p elastic scattering. The present data show no indication of any narrow structures. Instead, we find evidence for a broad $J^π=1/2^+$ state in $^9$He located approximately 3 MeV above the neutron decay threshold.

Explore related subjects

nucl-ex

Keep this discovery

BibTeX RIS

E. Uberseder, G. V. Rogachev, V. Z. Goldberg, E. Koshchiy, B. T. Roeder, M. Alcorta, G. Chubarian, B. Davids, C. Fu, J. Hooker, H. Jayatissa, D. Melconian, R. E. Tribble. 2015-04-03. Nuclear structure beyond the neutron drip line: the lowest energy states in $^9$He via their T=5/2 isobaric analogs in $^9$Li. https://doi.org/10.1016/j.physletb.2016.01.014

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Reinvestigation of the Yield of the Trinity Device

Previous published analyses of trinitite to determine the yield of the Trinity nuclear explosion used various estimates of the fraction of fission products that became incorporated in trinitite. Furthermore, these studies utilized nuclear data that has subsequently been revised. Utilizing a planar germanium detector, we observed gamma rays produced by the decays of both 137Cs and 239Pu from four samples of trinitite. From the observed 137Cs/239Pu ratios of and a simple analysis method based on current nuclear data and weapons debris studies, we find an average yield of 9.1+-4.5 kilotons from our four samples. While this result is substantially lower than the established total yield of 21 kilotons, it is in reasonable agreement that attributable to fissions in the 239Pu core alone.

nucl-ex↗

arXiv2026

Search for neutrinoless quadruple beta decay of $^{136}$Xe in PandaX-4T detector

The observation of neutrinoless quadruple beta decay (0$\nu$4$\beta$) in the absence of neutrinoless double beta decay (0$\nu$2$\beta$) has been argued to provide a strong indication that neutrinos are Dirac particles. We report a search for 0$\nu$4$\beta$ decay of $^{136}\text{Xe}$ using a total $^{136}\text{Xe}$ exposure of 148.4 kg$\cdot$yr, collected during the commissioning and the first science runs of the PandaX-4T experiment. No significant excess of events over the background is observed. A lower limit on the 0$\nu$4$\beta$ decay half-life of $^{136}\text{Xe}$ is set at 6.01 x $10^{24}$ yr at the 90% confidence level. This result establishes the most stringent constraint on this process in xenon, demonstrating the unique capability of the PandaX-4T detector in probing lepton number violation and shedding light on the fundamental nature of neutrinos.

nucl-ex↗

arXiv2026

Island of Inversion in neutron-rich cobalt isotopes revealed from mass measurements

Mass measurements of the ground and isomeric states of $^{68-70}$Co have been performed using the JYFLTRAP Penning-trap mass spectrometer at the IGISOL facility. The masses were measured, either for the first time for the isomeric states of $^{68}$Co and $^{70}$Co, or with greatly improved precision for the others, removing ambiguities in the mass surface beyond $N=40$. The ordering of the low and high-spin states in $^{68}$Co and $^{70}$Co has also been established. The results, supported by Large-Scale Shell Model and Discrete Non-Orthogonal Shell-Model calculations, show a gradual lowering of intruder states with increasing neutron number, eventually leading to an inversion in $^{70}$Co. These findings clarify previously proposed contradictory interpretations. Finally, we demonstrate the importance of including induced effective 3N forces for a consistent description of binding energies in the island of inversion near $N=40$.

nucl-ex↗