N14(He3

Abstract

The 14 N( 3 He,/) 14 0 reaction has been investigated at a 3 He energy of 44.6 MeV. New levels were observed in 14 0 up to an excitation energy of 18 MeV. An investigation of the ( 3 He,/) reaction on several other nuclei in the lp shell, notably 14 C and 15 N, revealed that the shapes and relative magnitudes of the angular distributions arising from single-particle transitions appear to fall into groups which are characterized by the specific shell-model transition involved. Utilizing this effect and other data, it was possible to make most probable spin and parity assignments of

Gamow-Teller Strengths in theA=14Multiplet: A Challenge to the Shell Model

“…model space. The existence of at least two 2 states in the low-excitation region of 14 O was already known [17]. It is interesting to note that simplified calculations using either a weak-coupling model [29] or considering the lowest 2 particle -4 hole configurations in 14 C made of a 12 C 2n configuration, with the two neutrons in the 1d 5=2 and 2s 1=2 orbitals [30] or, more generally, considering a full 0 2@!…”

“…The good energy resolution in both reactions allows one to resolve the GT strength distribution to individual excited states in the final nuclei. The 14 N 3 He; t 14 O reaction was already studied at 45 MeV 3 He beam energy [17], but at this energy no GT information could be extracted.…”

Observation of two-αemission from high-lying excited states ofNe18by complete-kinematics measurements

“…Instead, simple sequential emission via one-α daughter states ( 14 or a resonance of two α's ( 8 Be: 0 + , 2 + ) was simulated in the code. The possible α-decaying candidate states in 14 O were 10.89, 11.24, 11.97, 12.84, 13.01 MeV, and so on [19]. The distributions of θ c.m.…”

Dominance of High-Spin Two-Particle, One-Hole Transitions in (p, π−) Reactions

“…The correspondence for the strongest transitions observed (E x < 12 MeV) in 13 ' 14 C(j>,7r"") is not strictly to the OHu) stretched states considered above (involving only j > orbitals), but rather to states with the maximum spin (3 _ , E x =6.27 MeV in 14 0; | + , E x = 7.28 MeV in 15 0) attainable in a IHu) n~p excitation from the valence (Pi/ 2 ) subshell to the d 5 / 2 orbital. 13 Results for 13,14 C, 18 0(£,7T) suggest a rapid falloff in strength as J decreases from the maximum value [do/dQ, (30°) drops by a factor ~ 10 for A J of 2H], A similarly strong selectivity for high-spin stretched states has been observed, and attributed to momentum-matching conditions, in some heavy-ion-induced multinucleon transfer reactions, at comparable momentum transfers. 14 Stretched 2p-lh states may also be excited in (p,ir + ) reactions, if the incident proton interacts with a target nucleon from a high angular momentum orbital and the final-state nucleons are not Pauli blocked from coupling to maximum spin.…”