Study on Penetration of 4-MeV Electron Beam in Natural Rubber Latex

Abstract

Vulcanization with electron beam irradiation provides unique and high efficient processing for natural rubber latex. It is one of very interesting and effective industrial applications of particle accelerators. A radio-frequency (RF) linear accelerator (linac) and electron beam irradiation system have been developed for natural rubber vulcanization at the PBP-CMU Electron Linac Laboratory of the Plasma and Beam Physics (PBP) Research Facility, Chiang Mai University (CMU). This accelerator will be able to produce electron beams with maximum energy up to about 4 MeV. In this research, we used a Monte Carlo simulation program called GEANT4 to study transportation of 4-MeV electron beam with Gaussian transverse distribution through a vacuum window, an air gap and natural rubber latex. The vacuum window is made of 50-micron titanium foil and the natural rubber was placed 18 cm downstream the foil exit. Simulations of electron depth dose and transverse distribution in these media were conducted. In addition, calculation on the irradiation throughput was performed. The study results revealed that for the electron beam with Gaussian transverse distribution and an average energy of 4.06 MeV, the irradiation area should be 2.8 mm×2.8 mm with the depth of 8 mm. With this condition, the irradiation time of 0.02 second will provide the dose of at least 50 kGy per irradiated point, which is enough for the rubber vulcanization process. The overall irradiation throughput rate is 6.865 kg/hr.