Studies of the beam finding and targeting accuracy of the CAS–LIBB single-particle microbeam

A single-particle microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioengineering (LIBB), Chinese Academy of Sciences (CAS). The system was designed to deliver a defined number of hydrogen ions produced by a Van de Graaff accelerator, in an energy range of 2.0?3.0MeV, into an area smaller than the nuclei of individual living cells grown on thin plastic films. The beam is collimated by a borosilicate glass capillary that forms the beam-line exit. An computer integrated control program is developed to recognize the cells and to target them one by one for irradiation. Experiments for finding (capturing and recognizing) the microbeam position in the microscope imaging system and measuring the overall targeting accuracy of the facility are presented in this article. When a borosilicate glass capillary with 5?m inner diameter and 980?m length is used as the microbeam collimator, the overall targeting accuracy is that 91% aimed pit clusters are located within 2.4 ?m radius and 98% are within 3.6 ?m radius.