. 2026 Feb 9;33(Pt 2):260–270. doi: 10.1107/S1600577525011658

Table 3. Temperature at the centre of the beam footprint on the crystal T_c, standard deviation of height error along the beam footprint centre axis over 2×FWHM length std at three key moments: just after the XFEL pulse power loading; at first-turn time 1 µs; at period-end time t_per.

Results are compared between water (H₂O) and liquid nitrogen (LN₂) cooling, between three different repetition times t_per = 1, 10, 50 µs. Results for CW steady state analyses with either H₂O or LN₂ cooling are also included as reference. The reduction factor of the height error std by LN₂ cooling related to H₂O cooling f_reduction = std(LN₂)/std(H₂O). The same average XFEL power is assumed.

		H₂O cooling		LN₂ cooling
Height error (pm)		T_c (K)	std (pm)	T_c (K)	std (pm)	f_reduction by LN₂ cooling
t_per = 50 µs	Peak	543	3282	466	3778	0.87
	At 1 µs	512	1521	398	1826	0.83
	At t_per	399	19.3	129	0.02	1108

t_per = 10 µs	Peak	444	735	282	742	0.99
	At 1 µs	434	356	164	11.8	30
	At t_per	411	72.9	131	0.005	13748

t_per = 1 µs	Peak	419	210	169	56.8	3.7
	At 1 µs	416	147	134	0.15	1008
	At t_per	416	147	134	0.15	1008
CW steady state		417	163	139	1.82	89.5

Table 3. Temperature at the centre of the beam footprint on the crystal Tc, standard deviation of height error along the beam footprint centre axis over 2×FWHM length std at three key moments: just after the XFEL pulse power loading; at first-turn time 1 µs; at period-end time tper.

Table 3. Temperature at the centre of the beam footprint on the crystal T_c, standard deviation of height error along the beam footprint centre axis over 2×FWHM length std at three key moments: just after the XFEL pulse power loading; at first-turn time 1 µs; at period-end time t_per.