  the main physics goal for Back-n white neutron facility at China Spallation
Neutron Source (CSNS) is to measure nuclear data. The energy of neutrons is one
of the most important parameters for measuring nuclear data. Method of time of
flight (TOF) is used to obtain the energy of neutrons. The time when proton
bunches hit the thick tungsten target is considered as the start point of TOF.
T0 signal, generated from the CSNS accelerator, represents this start time.
Besides, the T0 signal is also used as the gate control signal that triggers
the readout electronics. Obviously, the timing precision of T0 directly affects
the measurement precision of TOF and controls the running or readout
electronics. In this paper, the T0 fan-out for Back-n white neutron facility at
CSNS is proposed. The T0 signal travelling from the CSNS accelerator is fanned
out to the two underground experiment stations respectively over long cables.
To guarantee the timing precision, T0 signal is conditioned with good signal
edge. Furthermore, techniques of signal pre-emphasizing and equalizing are used
to improve signal quality after T0 being transmitted over long cables with
about 100 m length. Experiments show that the T0 fan-out works well, the T0
signal transmitted over 100 m remains a good time resolution with a standard
deviation of 25 ps. It absolutely meets the required accuracy of the
measurement of TOF.
