β-spectroscopy of 11Li and 14Be —With a β-n-γ triple coincidence method

doi:10.1016/S0375-9474(97)00087-0

Nuclear Physics A

Volume 616, Issues 1–2, 14 April 1997, Pages 181-188

https://doi.org/10.1016/S0375-9474(97)00087-0 Get rights and content

Abstract

Experimental studies of β-decay measurements of the neutron drip line nuclei ¹¹Li and ¹⁴Be are presented. β-decay schemes of these nuclei are determined by measuring β-rays, delayed neutrons and γ-rays in triple coincidence. The decay schemes of both ¹¹Li and ¹⁴Be associated with single neutron emission are unambiguously determined. New levels in their daughter nuclei, ¹¹Be and ¹⁴B, are found. In addition, the deduced level scheme of ¹⁴B indicates the lowering of $2s_{12}$ single neutron orbital with respect to $1p_{12}$ orbital in the N=9 isotones. Such behavior is known to exist in N=7.

References (15)

R.E. Azuma
Phys. Lett. B
(1980)
T. Bjornstad
Nucl. Phys.
(1981)
M. Langevin
Nucl. Phys.
(1981)
M. Langevin
Phys. Lett. B
(1984)
F. Ajzenberg-Selove
Nucl. Phys.
(1990)
F. Ajzenberg-Selove
Nucl. Phys.
(1991)
J.P. Dufour
Phys. Lett. B
(1988)

There are more references available in the full text version of this article.

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Nuclear Physics A

Abstract

References (15)

Phys. Lett. B

Nucl. Phys.

Nucl. Phys.

Phys. Lett. B

Nucl. Phys.

Nucl. Phys.

Phys. Lett. B

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