Experimental evidence of core modification in the near drip-line nucleus 23O.
The longitudinal momentum (P(axially)) distributions of one- and two-neutron removal fragments ((21,22)O) of 23O from the reaction with a C target at 72 A MeV have been measured for the first time using a new direct time-of-flight method with nearly full acceptance for the breakup fragments. The unexpectedly narrow width of 21O ( 115 +/- 34 MeV/c in FWHM) is consistent with two neutrons occupying the 2s(1/2) orbital in 23O. This indicates modification of core (22O) structure for neutron halo-like sd shell nuclei near the drip line. This also suggests the lowering of the s orbital providing a justification for the N = 16 magic number.
Kanungo
Rituparna
R
RIKEN, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Chiba
Masami
M
Iwasa
Naohito
N
Nishimura
Shunji
S
Ozawa
Akira
A
Samanta
Chhanda
C
Suda
Toshimi
T
Suzuki
Takeshi
T
Yamaguchi
Takayuki
T
Zheng
Tao
T
Tanihata
Isao
I