Gamow-Teller strengths in the A = 14 multiplet: a challenge to the shell model.
A new experimental approach to the famous problem of the anomalously slow Gamow-Teller (GT) transitions in the beta decay of the A=14 multiplet is presented. The GT strength distributions to excited states in 14C and 14O were studied in high-resolution (d,2He) and (3He,t) charge-exchange reactions on 14N. No-core shell-model calculations capable of reproducing the suppression of the beta decays predict a selective excitation of Jpi=2+ states. The experimental confirmation represents a validation of the assumptions about the underlying structure of the 14N ground state wave function. However, the fragmentation of the GT strength over three 2+ final states remains a fundamental issue not explained by the present no-core shell model using a 6homega model space, suggesting possibly the need to include cluster structure in these light nuclei in a consistent way.
Negret
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A
Vakgroep Subatomaire en Stralingsfysica, Universiteit Gent, Proeftuinstraat 86, 9000 Gent, Belgium.
Adachi
T
T
Barrett
B R
BR
Bäumer
C
C
van den Berg
A M
AM
Berg
G P A
GP
von Brentano
P
P
Frekers
D
D
De Frenne
D
D
Fujita
H
H
Fujita
K
K
Fujita
Y
Y
Grewe
E-W
EW
Haefner
P
P
Harakeh
M N
MN
Hatanaka
K
K
Heyde
K
K
Hunyadi
M
M
Jacobs
E
E
Kalmykov
Y
Y
Korff
A
A
Nakanishi
K
K
Navrátil
P
P
von Neumann-Cosel
P
P
Popescu
L
L
Rakers
S
S
Richter
A
A
Ryezayeva
N
N
Sakemi
Y
Y
Shevchenko
A
A
Shimbara
Y
Y
Shimizu
Y
Y
Tameshige
Y
Y
Tamii
A
A
Uchida
M
M
Vary
J
J
Wörtche
H J
HJ
Yosoi
M
M
Zamick
L
L