McDaniel was skilled in constructing "atom smashing" devices to study the fundamental structure of matter and helped to build the most powerful particle accelerators of his time.

[2][3] McDaniel continued postgraduate studies when he moved to Cornell University, and in 1943 he completed his doctoral thesis, examining the absorption rates of neutrons in indium.

[2] From Cornell, McDaniel moved to MIT where he held a postdoctoral position, studying "the rapidly evolving field of fast electronics", which he applied to research in particle physics.

[4] After the outbreak of World War II, McDaniel joined Bacher in Los Alamos, New Mexico to work for the Manhattan Project, where he became a part of Robert R. Wilson's cyclotron research team.

[6] He was a co-founder of Cornell's Laboratory for Nuclear Studies (LNS) and had helped create the 300 megavolt (MeV) electron synchrotron, one of the first such accelerators in the world.

[6][7] McDaniel quickly earned a reputation as a hands-on designer as indicated by this episode in the construction of the 300 MeV synchrotron: The magnet coil was wound incorrectly, a fatal flaw.

Mac made a toy model of the coil, studied it carefully for an evening, and discovered an ingenious but simple way to repair it, which he did in about a day, and defused the crisis.

When constructed in 1979, the Cornell Electron Storage Ring became the world's primary source of information about one of the fundamental building blocks of matter, the b-quark.

[16]In 1975, 11 years before the Supreme Court decision in Meritor Savings Bank v. Vinson recognized sexual harassment as a violation of the Civil Rights Act of 1964, Carmita Dickerson Wood, an administrative assistant to McDaniel, quit her job after years of alleged sexual harassment by McDaniel, bringing her case to Lin Farley and the Working Women United organization which Farley chaired.