Slow extraction from the J-PARC main ring using a dynamic bump

A dynamic bump under the achromatic condition has been applied for third integer slow extraction from the Japan Proton Accelerator Research Complex main ring. This dynamic bump scheme has drastically reduced beam loss rate for slow extraction compared to that for a fixed bump mode. The low beam loss rate for slow extraction has been retained for high power operations. A beam power of 41−44.4 kW was achieved for physics runs using the slow extraction by applying the dynamic bump scheme. The beam profile measured just upstream of the target indicates that the beam spot at the target does not travel over the entire extraction time. This behavior is advantageous for experimental data acquisition.