A natural molybdenum source was used in a time projection chamber to look for five modes of ββ. We place half-life limits of 6.8×${10}^{17}$ yr on ββ(2ν), 1.3×${10}^{19}$ yr on ββ(0ν), and 7.5×${10}^{18}$ yr on ββ(0ν,B) for ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$, and limits of 2.3×${10}^{17}$ yr on ${\beta }^{+}$,EC(2ν) and 2.7×${10}^{18}$ yr on ${\beta }^{+}$,EC(0ν) for ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$.

• Received 6 July 1987

DOI:https://doi.org/10.1103/PhysRevC.36.2129