Excitation of giant magnetic and spin-isospin dipole states in radiative $pi$ capture on $sup 14$N and $sup 10$B

Journal Article · Mon Sep 01 00:00:00 EDT 1975 · Phys. Rev., C, v. 12, no. 3, pp. 921-937

OSTI ID:4146133

Baer, H W; Bistirlich, J A; de Botton, N; Cooper, S; Crowe, K M; Truol, P; Vergados, J D

The photon spectra in the capture of stopped pions on $sup 14$N and $sup 10$B were measured in the 50--150 MeV region with a high-resolution pair spectrometer. The total radiative capture branching ratios are 2.13 plus-or- minus 0.21 and 2.27 plus-or-minus 0.22%, respectively. The spectrum corresponding to the first 13 MeV excitation in each of the residual nuclei $sup 14$C and $sup 10$Be is dominated by the transition to the analog of a giant M1 state of the target nucleus. The ground state transitions in both nuclei are resolved experimentally. The measured branching ratio for the extremely weak $sup 14$C(g.s.) transition is (3 plus-or-minus 2) times10$sup -5$. There is evidence for selective excitation of the analogs of the giant diople spin-isospin states of $sup 14$N, of which the 3$sup -$ component appears to be the strongest. In $sup 10$B the transition strength to the giant resonance region is more fragmented. An analysis is presented that employs an impulse-approximation Hamiltonian with amplitudes taken directly from the fundamental process on the nucleon, $pi$$sup -$+p $Yields$ n+$gamma$, and shell-model wave functions obtained using realistic interactions in the 1s, 1p, and 2s-1d shells. Also, a calculation for the $sup 14$C(g.s.) transition from 1s capture using the ''elementary-particle soft-pion'' ansatz is presented.

• Research Organization: Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• NSA Number: NSA-33-004358
• OSTI ID: 4146133
• Journal Information: Phys. Rev., C, v. 12, no. 3, pp. 921-937, Journal Name: Phys. Rev., C, v. 12, no. 3, pp. 921-937; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

642005*
BRANCHING RATIO
CARBON 14-- NEUTRONS-- NITROGEN 14
IMPULSE APPROXIMATION
N68331 --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
6 <= A <= 19--Energy Levels & Transitions
N68351* --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
6 <= A <= 19--Nuclear Reactions & Scattering
PHOTONS
PIONS MINUS BERYLLIUM 10-- BORON 10-- NEUTRONS