Migration of nuclear shell gaps studied in the d(24Ne,pγ)25Ne reaction.
The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 is put on a firm footing by confirmation of this state's identity. The raised 3/2+ level is observed simultaneously with the intruder negative parity 7/2- and 3/2- levels, providing evidence for the reduction in the N=20 gap. The coincident gamma-ray decays allowed the assignment of spins as well as the transferred orbital angular momentum. The excitation energy of the 3/2+ state shows that the established USD shell model breaks down well within the sd model space and requires a revised treatment of the proton-neutron monopole interaction.
Catford
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WN
Department of Physics, University of Surrey, Guildford GU2 5XH, United Kingdom.
Timis
C N
CN
Lemmon
R C
RC
Labiche
M
M
Orr
N A
NA
Fernández-Domínguez
B
B
Chapman
R
R
Freer
M
M
Chartier
M
M
Savajols
H
H
Rejmund
M
M
Achouri
N L
NL
Amzal
N
N
Ashwood
N I
NI
Baldwin
T D
TD
Burns
M
M
Caballero
L
L
Casadjian
J M
JM
Curtis
N
N
de France
G
G
Gelletly
W
W
Liang
X
X
Pain
S D
SD
Pucknell
V P E
VP
Rubio
B
B
Sorlin
O
O
Spohr
K
K
Theisen
Ch
Ch
Warner
D D
DD