High spin states in the mirror nuclei 15O and 15N

NUCLEAR

HIGH

INSTRUMENTS

AND

SPIN STATES

L. KRAUS,

I. LINCK,

METHODS

146

IN THE MIRROR

J. C. SENS

Centre de Recherches Nuckaires,

and

(1977)

NUCLEI

“C

;

0

NORTH-HOLLAND

CO.

150 AND “N

Strasbourg-Cronenbourg,

F-67037

Strasbourg

Cedex, France

the 14C(p,y) reaction3). The ratio r/f,,,,, = 0.9 t 0.2 measured for this unbound level, experimentally establishes that the predominant mode of deexcitation is by y-ray emission. For the 15N levels at 13.15 MeV (11/2-) and 15.5 MeV (13/2+), r,/I&, <0.25. In the case of IsO, the t-y coincidence yield is weak by comparison. For the IsO levels at 10.45, 12.84, and 15.05 MeV, f,/T,,,,,
et al., Phys. Rev. 11C (1975) 1913. et al., Phys. Rep. 12 (1974) 201. et al., Phys. Lett. 56B (1975) 253.

( 6Li ,3bb 1 “N

lb0 Fig. 1.

PUBLISHING

M. TOULEMONDE

Some states in IsO and 15Nare strongly excited in 3-nucleon transfer reactions’$2) as in the and 12WLi, 3He) reactions at lzWLi, t) E6Li> 35 MeV (fig. 1). Angular distributions of outgoing particles’) have led to the suggestion that these levels had J&9/2. In the present study, a search for possible y-decay has been undertaken in an effort to understand the structure of these were done at states. The measurements E6~i = 44 MeV using a telescope (0 = 20”) and a Ge(Li) detector (0 = 90’). Fig. 2 for ‘*N shows the spectrum of 3He particles in coincidence with y-rays of E< 8 MeV. Only peaks corresponding to levels below 11 MeV appear, the most important being for the level at 10.7 MeV. Taking into account the y-ray decay scheme observed, this level corresponds to the 9/2+ level at 10.693 MeV in lSN found recently in

Pea

312

Fig.

2.

z&z

CANAL