Measurement of 181 MeV H~- ions stripping cross-sections by carbon stripper foil

摘要

The stripping cross-sections of 181 MeV H~1 (negative hydrogen) ions by the carbon stripper foil are measured with good accuracy. The present experiment was carried out at the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex). The stripping cross-sections for different charge states, also known as electron loss cross-sections of H~- ion, are denoted as σ_(-11), σ_(-10) and σ_(01). for both electrons stripping (H~-→H~+), one-electron stripping (H~- →H~0) and the 2nd-electron stripping (H~0→H~+) proceeding σ_(-10), respectively. We have established very unique and precise techniques for such measurements so as also to determine a foil stripping efficiency very accurately. The cross-sections σ_(-11), σ_(-10) and σ_(01) are obtained to be (0.002 ± 0.001) × 10~(18) cm~2, (1.580 ± 0.034) × 10~(-18) cm~2 and (0.648 ± 0.014) × 10~(17) cm~2, respectively. The presently given cross-sections are newly available experimental results for an incident H~- energy below 200 MeV and they are also shown to be consistent with recently proposed energy (1/β~2) scaled cross-sections calculated from the previously measured data at 200 and 800 MeV. The present results have a great importance not only at J-PARC for the upgraded H~- beam energy of 400 MeV but also for many new and upgrading similar accelerators, where H~- beam energies in most cases are considered to be lower than 200 MeV.