Gamow-Teller strength to 38K from the 38Ar(p,n) reaction and 38Ca( beta +) decay.

Gamow-Teller (1{sup +}) strength was studied in {sup 38}K with the analog reactions {sup 38}Ar({ital p},{ital n}){sup 38}K and {sup 38}Ca({beta}{sup +}){sup 38}K. The ({ital p},{ital n}) reaction was performed at 135 MeV using the beam swinger facility at the Indiana University Cyclotron Facility. Excitation-energy spectra were measured at 15 angles between 0{degree} and 63{degree}. Neutron energies were measured by the time-of-flight method using a large-volume plastic scintillator array at a flight path of 131.0 m. The overall energy resolution was 280 keV. Gamow-Teller (GT) strength was extracted from the measured angular distributions to discrete 1{sup +} final states. The {beta}-decay experiment was performed with the ISOLDE on-line mass separator facility at CERN. The {beta}-decay branching ratios were determined by observing the delayed {gamma} decays of {sup 38}K. These decay measurements provide an increased sensitivity over earlier measurements and are able to extract transitions down to {approximately} 10{sup {minus}4} of the strongest branches. The {ital B}(GT) values obtained from the two experiments are generally in good agreement, except for the transition to the first 1{sup +} state at 0.46 MeV, which is observed to be much weaker in the ({ital p},{ital n}) measurements. The {beta}-decay measurements provide good resolution andmore » high sensitivity while the ({ital p},{ital n}) measurements extend the {beta}-decay measurements to higher excitation energies. The summed {ital B}(GT) strength is {approximately}50{percent} of the simple Ikeda sum rule. The distribution of GT strength is in reasonable agreement with that predicted from a shell-model calculation using {open_quote}{open_quote}effective{close_quote}{close_quote} GT operators. {copyright} {ital 1996 The American Physical Society.}« less