Fragmentation from heavy ion beams in HIMAC BIO room calculated with PHITS and measured with Liulin

The Heavy Ion Medical Accelerator in Chiba (HIMAC), at the National Institutes for Quantum and Radiological Science and Technology, is not only an excellent cancer-treatment facility but also a facility to perform experiments related to radiation therapy, space radiation protection and basic nuclear physics. HIMAC BIO is an irradiation room used for experiments related to both radiobiology and physics. When performing such experiments, it is essential to know the experimental setup, as well as the beam characteristics, in details. The advantage of HIMAC BIO is that both narrow and broad parallel heavy ion beams (up to. 10 cm), with flat circular profile at the isocenter, can be used for experiments. Such beam is obtained by using scatterers, ridge filters, beam degraders, etc., similar to what is used during radiation therapy. However, these components decrease the energies of the primary beams and are sources of secondary particles. To be able to draw correct conclusions from the experimental results, and to be able to compare the measurements with simulations, it is crucial to know the real energy of the primary ions and the detailed beam composition at the location of the biological samples and the physical detectors. The energies of the primary ions are calculated from Bragg curve measurements with a Markus ionization chamber before each experiment. However, the exact beam composition including the fluence and energies of the secondary fragments and neutrons are usually unknown. The purpose ofdetailed information about the components in the beam line at the HIMAC BIO room to facilitate accurate particle and heavy ion transport simulations of the beam characteristics. The main sources of secondary particles have been investigated, and the beam composition was calculated with the 3-dimensional general purpose Monte Carlo this paper is to provide PHITS and compared with measurements using a Liulin exposed to various monoenergetic and SOBP heavy ion beams