Located in Tokai, about 60 miles south of the hard-hit city of Sendai, the accelerator was being used to generate neutrinos as part of an experiment at the Japan Proton Accelerator Research Complex, NewScientist.com reported Tuesday.
In June researchers said they had observed a kind of neutrino transformation never seen before in data collected before the earthquake.
Neutrinos are particles known to transform from one type to another spontaneously, but the kind of change seen at the Japanese complex not been observed before, researchers said.
The earthquake damaged roads at the complex, caused leaks in the buildings housing the accelerator and, most critically, knocked the accelerator's magnets out of alignment.
The magnets steer the beam of protons being accelerated and must be very precisely aligned to accomplish this, researchers said.
After re-aligning the magnets, researchers successfully sent a proton beam through all parts of the accelerator for the first time on Dec. 26 and are conducting tests in the hopes of restarting experiments by the end of January.