Thickness measurements of the stripper foils in the J-PARC 3-GeV RCS

Yoshimoto, Masahiro  ; Yamazaki, Yoshio ; Saha, P. K.   ; Kinsho, Michikazu  ; Yamamoto, Shunya; Kawaguchi, Kazuhiro*; Sugai, Isao*; Irie, Yoshiro*

A stripper foil plays an important role for charge-exchange multi-turn injection in high intensity accelerators like the RCS of J-PARC. In order to optimize the foil thickness, the stripping efficiency is obtained by using beam for various thicknesses of the foils. The RCS has three stripper foils. By using a proper combination of three foils, the total H beam, the H and the H beam can be measured separately. As for determining an accurate stripping efficiency, it is very important to know an actual foil thickness. For that purpose, we employed several other methods to measure the foil thickness. The simplest method is the weighing of the foil. Further more accurate methods with the particle thickness gauge or the RBS are also adopted. In addition, the cross section of the foil is observed and the thickness is measured directly with the SEM. Through such direct measurements of the foil thickness, an accurate stripping efficiency of the RCS stripper foil can be established.