Study on the beam intensity upgrade of J-PARC main ring

The beam intensity upgrade of the main ring of the Japan Proton Accelerator Research Complex (J-PARC) have been studied with simulations. The main ring delivered 30 GeV proton beams with the beam power of 500 kW at maximum to the neutrino facility in the recent operation. The number of accelerated protons was 2.61×10¹⁴ protons per pulse (ppp). The upgrade plan aims at a beam power of 1.3 MW with reduced cycling time of 1.16 s compared to the present cycle time of 2.48 s. Upgrades of the magnet power supplies and RF system are in progress to achieve faster cycling. Furthermore, an intensity upgrade to 3.3×10¹⁴ ppp is necessary, while keeping the beam loss under control to reduce residual radiation. The high intensity operation has been simulated with the particle tracking program SCTR, taking space charge effects into account. The simulations were performed for the present beam intensity to reproduce the present status of the beam loss and for the target beam intensity to estimate the beam loss. We studied the interaction of the beam with structure resonances as main cause of the beam loss. Possible alternative operational tunes were explored to improve beam survival. (author)