Bunch-size measurement of the high-intensity H beam with 3 MeV by the bunch-shape monitor

Kitamura, Ryo   ; Futatsukawa, Kenta*; Hayashi, Naoki  ; Hirano, Koichiro  ; Kondo, Yasuhiro   ; Kosaka, Satoshi*; Miyao, Tomoaki*; Nemoto, Yasuo*; Morishita, Takatoshi  ; Oguri, Hidetomo  

The new bunch shape monitor (BSM) is required to measure the bunch size of the high-intensity H beam with 3 MeV at the front-end section in the J-PARC linac. The carbon-nano tube wire and the graphene stick are good candidates for the target wire of the BSM, because these materials have the enough strength to detect the high-intensity beam. However, since the negative high voltage of more than a few kV should be applied to the wire in the BSM, the suppression of the discharge is the challenge to realize the new BSM. After the high-voltage test to investigate the effect of the discharge from the wire, the detection of the signal from the BSM was successful at the beam core with the peak current of 55 mA using the graphene stick. The preliminary result of the bunch-size measurement is reported in this presentation.