  The performances of Low Gain Avalanche diode (LGAD) sensors from a neutron
irradiation campaign with fluences of 0.8 x 10^15, 15 x 10^15 and 2.5 x 10^15
neq/cm2 are reported in this article. These LGAD sensors are developed by the
Institute of High Energy Physics, Chinese Academy of Sciences and the Novel
Device Laboratory for the High Granularity Timing Detector of the High
Luminosity Large Hadron Collider. The timing resolution and collected charge of
the LGAD sensors were measured with electrons from a beta source. After
irradiation with a fluence of 2.5 x 10^15 neq/cm2, the collected charge
decreases from 40 fC to 7 fC, the signal-to-noise ratio deteriorates from 48 to
12, and the timing resolution increases from 29 ps to 39 ps.
