Evidence for a new low-lying resonance state in 7He.
Low-lying resonance states in 7He(6He+n), formed after fragmentation reactions of a 227 MeV/nucleon 8He beam on a carbon target, have been studied. Coincidences between 6He nuclei and neutrons, corresponding to the one-neutron knockout channel in 8He, were selected. The relative energy spectrum in the 6He+n system shows a structure, which is interpreted as the 7He ( Ipi = 3/2(-)) ground state, unbound with 0.43(2) MeV relative to the 6He+n system and a width of Gamma = 0.15(8) MeV overlapping with an excited ( Ipi = 1/2(-)) state observed at 1.0(1) MeV with a width of Gamma = 0.75(8) MeV.
Meister
M
M
Experimentell Fysik, Chalmers Tekniska Högskola och Göteborgs Universitet, S-412 96 Göteborg, Sweden.
Markenroth
K
K
Aleksandrov
D
D
Aumann
T
T
Axelsson
L
L
Baumann
T
T
Borge
M J G
MJ
Chulkov
L V
LV
Dostal
W
W
Eberlein
B
B
Elze
Th W
TW
Emling
H
H
Forssén
C
C
Geissel
H
H
Hellström
M
M
Holzmann
R
R
Jonson
B
B
Kratz
J V
JV
Kulessa
R
R
Leifels
Y
Y
Leistenschneider
A
A
Mukha
I
I
Münzenberg
G
G
Nickel
F
F
Nilsson
T
T
Nyman
G
G
Richter
A
A
Riisager
K
K
Scheidenberger
C
C
Schrieder
G
G
Simon
H
H
Tengblad
O
O
Zhukov
M V
MV