Misreading of pressure measurement by radiation, and its measures

In the SPring-8 Storage Ring, the pressure measured by Bayard-Alpert gauge near photon-absorber were not observed aging effects by a beam self-cleaning. As the result of investigations of this phenomenon, three causes of misreading of pressure measurement were found; (1) irradiation of the scattered X-ray to gauge head, (2) a large amount of electronic inflow to gauge head, (3) irradiation of the scattered X-ray to gauge cable. We took measures to the misreading, for example shielding of gauge heads and cables etc, and came to be able to measure pressure within tens of percent errors. (author)