Periodicity of 151 days in outer heliospheric anomalous cosmic ray fluxes

Statistically significant variations have been observed in the differential flux of similar to 27-MeV anomalous cosmic ray (ACR) oxygen, helium, and p rotons at the Voyager 1 spacecraft during 1998 and 1999 (at a helioradius o f similar to 73 AU). The quasiperiodic variations are in phase, with oxygen and helium having periods near 151 days, while protons exhibit a period of similar to 146 days. The Voyager 1 ACRs vary by similar to 30% with respec t to the trend, and similar galactic cosmic ray variations, if they exist, must be less than similar to5%, probably much less. No similar, significant periodicities have been detected for these same ACR species at Voyager 2 ( at 57 AU) during this period. We report on these and other periodicities in the Voyager Low Energy Charged Particle experiment measurements and addres s the possible connection between this similar to 151-day ACR periodicity a nd the previously discovered similar to 154-day periodicities in solar flar es, the interplanetary magnetic field, and other phenomena.