• A. Miura, N. Kikuzawa, T. Maruta, K. Yamamoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• Z. Igarashi, T. Miyao
  KEK, Ibaraki
• M. Ikegami
  J-PARC, KEK & JAEA, Ibaraki-ken
• H. Sako
  JAEA, Ibaraki-ken
• S. Sato
  JAEA/LINAC, Ibaraki-ken

Since November, 2007, J-PARC Linac has been operated at 7.2kW beam power. During the operation, beam losses possibly caused by the H0 particles generated by the interaction between H^- beam and residual gas in the transport line were observed in the SDTL (Separated-type Drift-Tube Linac) section. In the linac operation, Ar-CO2 gas proportional counters are employed for the measurement of beam loss, but they are also sensitive to background noise of X-ray emitted from RF cavities. In this section, protons, secondary hadrons and gamma rays would be mainly generated as a beam loss, but it is not easy to estimate real beam loss using the proportional counter. The plastic scintillation counters with less X-ray sensitivity and 3He proportional counters with high thermal neutron sensitivity will be also employed to measure the beam loss. The combination of these detectors would bring more accurate beam loss measurements with suppression of X-ray noise. A measurement of emission position and angle distributions of protons due to H^- beam loss is being planed. This result would lead to clarify the source of beam loss. This paper reports status of beam loss evaluation using these detectors.