Speaker
Description
The pulsed spallation neutron source at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC) consists of a mercury target, three liquid-hydrogen moderators and a beryllium and iron reflector, providing high intense pulsed neutron beam toward to 21 instruments. As of February 2026, the neutron source has been operating stably with 700 kW proton beam. In May 2024, the MLF achieved its operational goal of 1 MW at 25 Hz for two months during user operation.
In both 2024 and 2025, moisture in a helium vessel was detected during beam operation, leading the beam operation stop. In each case, the target vessel was replaced with a new one. The current target vessel is challenging toward a two-year operation under 800 kW equivalent proton beam. This summer, the moderators and reflector will be replaced for the first time since beam operation began in 2008. The proton beam window will also be replaced with a new one.
Ongoing efforts to improve the neutron source include the development of the mitigation technique for cavitation damage in target vessel, abnormal incident detection of target vessel, and new material for moderators and a reflector.
In this presentation, I will report on the current status and upgrade plan of the pulsed spallation neutron source at MLF, J-PARC.