Voyager 1 Observations of Galactic Cosmic Ray Isotopes in the Very Local Interstellar Medium: Evidence for Primary 2H and B

We present the first measurements of the energy spectra of the isotopes of Galactic cosmic rays (GCRs) with nuclear charge $Z$=1--14 in the very local interstellar medium (VLISM). The observations are from the Cosmic Ray Subsystem (CRS) on the Voyager~1 (V1) spacecraft and cover the $Z$-dependent energy range from $\sim$3-661 MeV/nucleon. The data are fit to eight models using the GCR propagation code \galprop{}, and provide a new set of GCR elemental source abundances. The models all have injection spectra as power laws in rigidity, all with the same power-law index, and fit exclusively to the V1 data. The eight models differ in the relative abundances and by having two options for production cross sections and four options for total fragmentation cross sections. The VLISM energy spectra generated by all eight models agree reasonably well with the observed VLISM energy spectra for the isotopes with $Z$ from 1--14. However, in all models it was necessary to add contributions from a primary source of $^2$H and B.