Modelling of radiation damage and beam-induced heating of room-temperature samples at extremely high flux MX beamlines

The upgrade of the third-generation synchrotrons to diffraction-limited storage rings will enable a gain of up to two orders of magnitude in brilliance and further enable the creation of multiple macromolecular crystallography (MX) beamlines capable of delivering fluxes in excess of 1 × 10¹⁵ photons s^-1, here called extremely high flux (EHF) MX beamlines. These beamlines, such as ID29 at ESRF-EBS, BioCARS at APS-U and MicroMAX at MAX IV, have all been either partly or solely geared towards delivering time-resolved MX experiments at room temperature and realizing microsecond time resolutions. Given the uncharted territory of using dose rates in excess of 50 GGy s^-1 at many facilities, this article examines some of the expected consequences, suggesting that considerable attention should be paid to beam heating effects for crystals <20 µm exposed to 1 × 10¹⁵ photons s^-1. Several strategies have been proposed to mitigate heating effects when high dose rates are required for a time-resolved experiment, including reducing the absorbed dose by increasing the size of the crystal and the beam profile, and explicitly exploiting the motion of the crystal in serial crystallography delivery systems. The model presented here is intended to serve as a useful tool to inform experimental design and support users' decision making in such cases.