Measurement of Momentum Spread of the Injection Beam with Longitudinal Tomography Method in the J-PARC RCS

Yoshimoto, Masahiro  ; Harada, Hiroyuki  ; Hotchi, Hideaki  ; Saha, P. K.   ; Tamura, Fumihiko   ; Yamamoto, Masanobu   ; Kinsho, Michikazu  

In the J-PARC RCS, the beam tuning toward the design output beam power of 1MW were started after the completing of the beam energy and beam current upgrades in the LINAC. One of the important issues to achieve the 1MW beam operation is the optimization of the injection beam from the LINAC. Due to the longitudinal beam tuning in the LINAC, the momentum spread of the injected beam into the RCS was measured with the longitudinal tomography method. Our longitudinal tomography tool had been developed using the simple algorithm with the Convolution Back Projection (CBP) method for the beam storage mode of the RCS. Accordingly, we improved this tool to expand into the acceleration mode. By tuning the tank level of the debuncher 2 in the LINAC, it can be measured the momentum spread was shifted from 0.06% to 0.15%. Moreover, these distributions of the momentum spread are consistent with the simulation results.