Room: Exhibit Hall
Purpose: To measure acute effects of neutron exposure on Intel-based microcomputers in a Mevion S250 double scatter proton treatment room accounting for CPU process sizes.
Methods: Computer configurations used Intel Core i5-500(x2), Core i3-300(x2), Core2 Duo E8000(x2), E7500(x1), E6000(x2), Pentium 4 Prescott(x2), Pentium 4 Northwood(x2) family CPUs with process sizes of 32nm, 32nm, 45nm, 45nm, 65nm, 90nm, and 130nm, respectively. Computers were subjected to 24h stress testing prior to neutron exposure to ensure stability. Proton beams with range 25cm, modulation 20cm, and field size 20cmx20cm were delivered to 30cmx30cm solid water blocks placed at 164.4cm effective SSD, and CPUs were placed at 40cm past isocenter. Neutron effective doses at CPU location were measured with a Wendi-2 neutron detector. Total dose of 80Gy was delivered to solid water for each CPU tested. Acute effects of radiation on computerâ€™s operation during irradiation were determined by Prime95 stress tests and operating system (OS) error reporting. After irradiations, computer stabilities were further stress tested each for 24h and both RAM and HDD integrities were tested.
Results: Computers experienced fatal system errors during neutron exposure resulting in OS crash with OS reporting errors in the CPU core. Average doses for fatal errors in the 32nm(i5), 32nm(i3), 45nm, 65nm, 90nm, and 130nm chips were 2.44mSv, 6.29mSv, 2.46mSv, 4.35mSv, 2.67mSv, 3.14mSv, respectively. No permanent hardware defects in RAM or HDDs for any system were detected. Post-exposure stress testings revealed no permanent CPU damage effect.
Conclusion: Acute neutron exposure of microcomputers renders CPUs unstable and prone to unrecoverable errors. Additional factors besides process size appear to have effect on processor stability as induced errors did not correlate with changes in process size. Core i3 processors were consistently more stable than Core i5 at equivalent process sizes. Permanent effects were not observed on CPUs at doses tested.
Not Applicable / None Entered.