The muon , which has a greater mass ( when its not moving ) than an electron , drags the heavier triton and the deuteron to it , creating something called a muonic heavy hydrogen ion . The muon , with a rest mass about 207 times greater than the rest mass of an electron , is able to drag the more massive triton and deuteron about 207 times closer together to each other in the muonic ( d - Î 1\/4 - t ) + molecular ion than can an electron in the corresponding electronic ( d-e-t ) + molecular ion . The average separation between the triton and the deuteron in the electronic molecular ion is about one angstrom ( 100 pm ) , so the average separation between the triton and the deuteron in the muonic molecular ion is about 207 times smaller than that .