Production Cross Sections of Fragments from Beams of 400-650 MeV per Nucleon 9Be, 11B, 12C, 14N, 15N, 16O, 20Ne, 22Ne, 56Fe, and 58Ni Nuclei Interacting in a Liquid Hydrogen Target. II. Isotopic Cross Sections of Fragments

We have measured the isotopic cross sections of 130 secondary fragmentation isotopes from 10 different beam nuclei from ⁹Be to ⁵⁸Ni that were accelerated to between 400 and 650 MeV nucleon^-1 at the SATURNE Accelerator in France in 1993 and 1994. These beam nuclei interacted in a 1.52 g cm^-2 thick liquid hydrogen target, and the isotopic fragments were observed. This is the first use of a pure hydrogen target with a thickness approximating the amount of hydrogen traversed by cosmic rays in our Galaxy to measure cross sections. Several of the beam charges such as ⁹Be, ¹¹B, ¹⁵N, and ²²Ne have not had their fragmentation cross sections measured previously. The isotopic cross sections from the ¹²C, ¹⁴N, ¹⁶O, ²⁰Ne, ⁵⁶Fe, and ⁵⁸Ni beam interactions are compared with earlier measurements by our group using a CH₂ - C target subtraction technique to determine the hydrogen cross sections. The overall agreement between the new measurements and the earlier measurements using a CH₂ - C target subtraction is excellent with a systematic consistency between measurements ~3%-5%. These new isotopic cross sections define the Galactic production of the secondary isotopes ¹⁰Be, ¹⁰B, ¹¹B, ¹³C, ¹⁴N, ¹⁵N, and ¹⁸O as well as Fe and Ni secondary decay isotopes from Cl to Co to a level of precision of ~3%-5%. These cosmic-ray isotopes are important for understanding the nucleosynthesis in the cosmic-ray sources as well as tracing the detailed propagation history of cosmic rays in the Galaxy.