Upgrade of the RF reference system at J-PARC LINAC

Futatsukawa, Kenta; Fang, Z.*; Kobayashi, Tetsuya*; Michizono, Shinichiro*; Fukui, Yuji*; Shinozaki, Shinichi; Sato, Fumiaki

no journal, , 

In J-PARC, the accelerator systems are controlled using the master clock of 12 MHz made in Computer/Network Equipment Room (CER) of the central control building. In the present system, the low-level radio frequency (LLRF) system of LINAC is based on the reference signal of 312 MHz synchronized with the 12 MHz clock. For the upgrade of LINAC, not only 312 MHz but also 960 MHz reference signals are necessary. Therefore a new RF reference signal oscillator was installed at J-PARC LINAC. This module has the 80 MHz Oven Controlled Crystal Oscillator (OCEO) and the Phase Looked Loop (PLL) under temperature control by Peltier module. The phase noise of the output signal in this module was measured by the signal source analyzer. The jitter of the output signal, which was estimated from the integration of phase noise from 10 Hz to 1 MHz, becomes about 40 fsec and was two order smaller than that of the old system (about 1700 fsec) by the installation of new oscillator and the optimization of the path of the master clock. It can be expected to improve the operating ratio in J-PARC LINAC and to suppress the activation in each device can be expected.