In this paper, we present differential cross sections and complete sets of polarization transfer coefficients, D i j , obtained in the 13 C(p ជ ,n ជ) 13 N reaction studied at zero degree and at 197 MeV incident proton energy. The complete set of polarization observables is used to obtain the Fermi and Gamow-Teller ͑GT͒ cross section contributions in the ground state transition, which are then used to deduce GT transition strengths. The sum of the GT strength up to 20 MeV of excitation is compared with shell model calculations. In the region between 20 to 46 MeV of excitation, the differential cross section has been separated in spin and nonspin components.

The search for an g bound state in the double charge exchange (DCX) reaction to the double isobaric analog state (DIAS) O(sr+, n )' Ne(DIAS) has been carried out at LAMPF using the P channel and the LAS spectrometer. An excitation function for this reaction was measured for energies ranging from 350 to 440 MeV and for momentum transfers of 0, 105, and 210 MeV/c. The measured cross sections tend to agree with previous results for DCX on O. The measured excitation function shows some evidence for structure near the rI production threshold. PACS number(s): 25.80.Gn, 27.20.+n Coupled-channel calculations by Bhalerao and Liu have shown that the q-X interaction is attractive for nuclei with A &12 [1]. Recent calculations by Haider and Liu [2] have predicted that a bound state between an rl and a nucleus may occur as an intermediate state in pion double charge exchange (DCX). Such an effect would compete with vr' and rl channels in the continuum. The existence of such a mesic nucleus would lead to a resonancelike structure in the DCX excitation function at fixed momentum transfer, due to the interference between these channels. Calculations made for the reaction C(sr+, vr ) O(DIAS) predict that this structure should occur with a fluctuation ratio of (cr~"-o~;")/o~"~g, 79'%%uo for DCX reactions at a momentum transfer of q = 210 MeV/c [2]. It should occur at the rl production threshold with a width on the order of 10 MeV and add to the smoothly varying continuum amplitude. It should be noted that because of the greater level density compared to C, the fluctuation ratio for 0 may be smaller. Chiang et al. predict that the width of the rl bound state for a nucleus like oxygen will be around 30 MeV or larger [3]. If the width is larger than the 10 MeV predicted for C then the fluctuation ratio will also be smaller. Haider and Liu [2] note that if the width is a factor of four greater than the 10 MeV expected, the fluctuation ratio should still be~20%%uo at q = 210 MeV/c. For the reaction isO(~+, vr ) (DIAS) the rl threshold occurs when the rl is bound in the first nuclear orbital of rsF [2]. Taking into account the excitation energy to the isobaric analog state (T = 1) in sF, the resonance effect should be seen at 420 MeV. Lich et al. [4] have seen possible evidence of an rl bound state from studies of the reaction A(sr+, p)gA-1. How-ever, Chrien et al. [5], found no evidence of the creation of an rl bound state with width 9 MeV, but their upper limit, for a Huctuation ratio 3 of the predicted size, is larger than that estimated by Haider and Liu. This paper reports an attempt to confirm this new type of nuclear matter with an experiment at LAMPF devised to search for an rl-nucleus bound state in the DCX reaction O(x+, vr ) (DIAS). The excitation function for this reaction was measured for momentum transfers of q = 0, 105, and 210 MeV/c for energies ranging from T = 350 to 440 MeV.This experiment was carried out using the Large Acceptance Spectrometer (LAS) in the Ps East channel at LAMPF, as configured for DCX measurements...