KEK digital accelerator

The High Energy Accelerator Research Organization KEK digital accelerator (KEK-DA) is a renovation of the KEK 500 MeV booster proton synchrotron, which was shut down in 2006. The existing 40 MeV drift tube LINAC and RF cavities have been replaced by an electron cyclotron resonance (ECR) ion source embedded in a 200 kV high-voltage terminal and induction acceleration cells, respectively. The High Energy Accelerator Research Organization KEK digital accelerator (KEK-DA) is a renovation of the KEK 500 MeV booster proton synchrotron, which was shut down in 2006. The existing 40 MeV drift tube LINAC and RF cavities have been replaced by an electron cyclotron resonance (ECR) ion source embedded in a 200 kV high-voltage terminal and induction acceleration cells, respectively. A DA is, in principle, capable of accelerating any species of ion in all possible charge states. The KEK-DA is characterized by specific accelerator components such as a permanent magnet X-band ECR ion source, a low-energy transport line, an electrostatic injection kicker, an extraction septum magnet operated in air, combined-function main magnets, and an induction acceleration system. The induction acceleration method, integrating modern pulse power technology and state-of-art digital control, is crucial for the rapid-cycle KEK-DA. The key issues of beam dynamics associated with low-energy injection of heavy ions are beam loss caused by electron capture and stripping as results of the interaction with residual gas molecules and the closed orbit distortion resulting from relatively high remanent fields in the bending magnets. Disturbing as it may sound, imagine cancer cells located near a human organ, cells that need to be treated. One of the most promising treatments is to irradiate cancer cells with high energy particles in order to ionize the DNA molecules in the cancer cells, breaking the molecules and killing the cells.Doctors can use radiation to damage the cancer cells but not the healthy cells around them. Particle therapy uses a property of particles called the Bragg peak of energy disposition. When a particle travels through a material, it deposits energy to its surroundings as it travels, before it comes to a complete halt. It turns out that ions lose most of their energy immediately before they come to stop. This property can be used to target cancer cells that are located at certain distance from the skin, without affecting healthy tissues on its way. Another well known radiation therapy for cancer, X-ray therapy, cannot do this. The energy loss spectrum is much broader so that much of the energy gets absorbed by the surrounding, damaging unwanted regions. This feature remains the same for the recently developed technique called intensity-modulated radiotherapy CHHIP.