Almost 10 years later McMillan did skin the cat and found out that one could preserve synchronous orbits and focusing, by changing the frequency of the cyclotron and that hadn't been possible in 1936, but it was very possible in 1945 because in the meantime, radar had been developed at the MIT Radiation Lab, and so by the confluence of technical development and an ingenious inventor, this Synchrocyclotron was... was developed. It was invented at the same time in Russia by [Vladimir] Veksler and it was then built almost immediately after the war in Berkeley and was used very effectively by the Berkeley group including Panofsky. And at the same time another instrument was invented by Don Kerst at Illinois which was the Betatron in which electrons were accelerated, already having relativistic velocities, keeping the same orbit all the time. Then Macmillan and Veksler said 'Well one could combine these two and have a Synchrotron where... which was... betatron with changing frequency', which is nowadays the preferred method of accelerating particles to very high energy.