The manufacturer has introduced the new EBT2 film model so as to improve its predecessor, the EBT radiochromic film model. According to the manufacturer, some of its main advantages include a higher tolerance to light exposure and it can correct non-uniformity of the active layer thickness using a marker dye. However, the equivalence in uniformity between both models was questioned by some authors, and the asymmetrical configuration of layers of the EBT2 film model produces a new dependence on the film side being scanned (front and back orientation). In this study, the EBT2 radiochromic film model was compared with the EBT model and the new marker dye feature was assessed. We also compared this correction method with a pre-irradiated pixel value correction method. An Epson Expression 10000XL scanner in transmission mode was used to scan the films and the red channel response was analyzed. We confirmed the lower-measured signal dependence on the visible light exposure of the EBT2 film model. Differences in pixel values remained below 0.5% for a minimum of 15 days. In regard to the uniformity, similar results for EBT2 and EBT film models were obtained; in both cases inhomogeneity was found to be less than 1%, in relative pixel value from the mean. However, we found that the signal-to-noise ratio was reduced for low doses by 37% for old EBT2 batch and by 21% for new EBT2 batch compared to signal-to-noise ratio for EBT. The EBT2 film model's pixel value difference for the front and back orientation reached up to 1.0% in the red channel. Our results did not show a clear advantage between to use a pre-irradiated pixel value correction and to use the manufacturer's correction.

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The Linac Coherent Light Source II (LCLS-II) will be a hard X-ray Free Electron Laser whose linac can deliver a 1.2 MW CW electron beam with bunch rates up to 1 MHz. To efficiently generate such a high power beam, Super-Conducting Radio-Frequency (SCRF) cavities will be installed in the upstream portion of the existing 3 km Linac at the SLAC National Accelerator Laboratory. The 9-cell niobium cavities will be cooled at 2K inside 35 cryomodules, each containing a string of eight of those cavities followed by a quadrupole. The strong electromagnetic fields in the SCRF cavities will extract electrons from the cavity walls that may be accelerated. Most such dark current will be deposited locally, although some electrons may reach several neighboring cryomodules, gaining substantial energy before they hit a collimator or other aperture. The power deposited by the field emitted electrons and the associated showers may pose radiation and machine protection issues at the cryomodules and also in other areas of the accelerator. Simulation of these effects is therefore crucial for the design of the machine. The in-house code Track3P was used to simulate field emitted electrons from the LCLS-II cavities, and a sophisticated 3D model of the cryomodules including all cavities was written to transport radiation with the Fluka Monte Carlo code, which was linked to Track3P through custom-made routines. This setup was used to compute power deposition in components, prompt and residual radiation fields, and radioisotope inventories.

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