Laser ion source for Columbia University's microbeam

A laser ion source that will be installed on the new High Voltage Engineering (HVE) 5 MV Singletron accelerator at the Columbia University Radiological Research Accelerator Facility (RARAF) will expand the linear energy transfer (LET) range available for irradiation experiments with mammalian cells. Through laser ablation the laser ion source can produce heavy ions with high charge states from a solid target; after acceleration, these ions will have sufficient energy to irradiate cells on a thin surface at atmospheric pressure. A high-power 100 Hz pulsed Nd:YAG laser used with the laser ion source has produced aluminum ions with charge states greater than nine. Proper power management issues are important in obtaining the high charge states while protecting sensitive laser optics. We expect that the laser ion source will enable us to use ions from hydrogen to iron, providing an LET range of about 10-4500 keV/μm for cell targets