Radiation measurement around a 10-T superconducting wiggler at SPring-8

In August 2002, a 10-T superconducting wiggler was installed in the 8-GeV electron storage ring at SPring-8. High-energy (∼3 MeV) and intense synchrotron radiation was produced from the wiggler, and scattered photons were generated by the interaction of synchrotron radiation with photon absorber materials. The intense radiation environment in the storage ring tunnel damages accelerator components, such as cable insulators and coils for electromagnets. To suppress such damage, it is necessary to understand the dose distribution and the spectrum of scattered photons near the wiggler. The dose distribution and the spectrum of scattered photons from the photon absorber was measured by thermoluminescent dosimeters (LiF TLD) with lead filters (0, 0.5, 1, 3, 6 mm in thickness). At the same time, alanine dosimeters and GafChromic film (made of polyethylene) were used to measure the dose of photons which exceeded the dynamic range of TLD dosimeters. The results of an experimental data analysis showed that, as expected, photons of energies of several hundred keV were scattered over a wide range.