Active thermal drift compensation on Linac4 reference line

Linac4 uses RF signal with frequency of 352 MHz for accelerating the injected particles (negative hydrogen ions). It is important that the accelerating voltage is applied at the correct moment so that the particles are accelerated (to gain energy) or decelerated (to make the particle bunch more compact). This basically means that the accelerating signal (voltage) for each accelerating cavity must have correct frequency and phase.