In Memoriam - Jack Kraushaar

Jack J. Kraushaar was one of a handful of talented young physicists who moved to Boulder in the late 1950’s, and built a world-class cyclotron at the edge of the prairie.

Jack earned a BS degree in Physics in 1944 from Lafayette College. He served in the Navy as a tactical radar officer during World War II. He earned a Ph.D. in physics at Syracuse University in 1952. He conducted doctoral research in nuclear physics at Brookhaven National Laboratory, and served on the physics faculty at Stanford University.

Professor Kraushaar joined the faculty of the CU Department of Physics in 1956, the same year as David Lind and George Gamow. This marked the beginning of a period of remarkable transformation for the department. Jack and David were the faculty leaders in creating, designing, and running the University of Colorado Cyclotron. They were the principal investigators of the contract from the U. S. Atomic Energy Commission for a design study of a cyclotron with azimuthally varying magnetic field. Such cyclotrons had been proposed to overcome the problem that conventional cyclotrons with azimuthally symmetric magnetic fields were limited to non-relativistic energies. Within a year, that contract had been modified to cover the design and construction of a 52-inch cyclotron capable of accelerating protons to 30 MeV, as well as accelerating deuterons, helium three ions, and alpha particles, one of only three similar cyclotrons in the country. The design process was led by Jack, David, Rod Smythe and Martin Rickey. A key feature of the machine was its ability to deliver particles to the target with a continuously variable range of energies.

The State of Colorado provided funds for a building to house the cyclotron, and the facility became the CU Nuclear Physics Laboratory with Jack and Dave as co-directors. It was one of only three similar machines in the nation, the competitors being Berkeley and Oak Ridge. All three laboratories reported successfully accelerating proton beams at the 1962 Accelerator Conference at UCLA. In addition, the CU Nuclear Physics Laboratory reported successfully accelerating negative hydrogen ions and extracting them from the magnetic field by stripping their electrons off by passing them through a thin foil. That technique led to the construction of a much larger negative ion cyclotron called TRIUMF at the University of British Columbia. The CU Nuclear Physics program conducted pioneering research for more than twenty-five years, providing research and educational opportunities for hundreds of undergraduate students, graduate students, and post-doctoral fellows. 

Jack was regarded as an excellent physicist, mentor, leader and, according to friends, provided a civilizing influence for the team of scientists.

Jack was also a first-rate teacher. He is most famous for creating CU Physics’ very successful course Energy and the Environment, which continues to enroll hundreds of students each year. He was co-author with Bob Ristinen of the very widely used undergraduate textbook with the same name, which is now in its fifth edition.

Jack retired from the University of Colorado in 1988 and was awarded the title Professor Emeritus. Together with Professor Emeritus Al Bartlett, Jack authored A History of the Department of Physics of the University of Colorado at Boulder in 2002. The book documents the remarkable evolution of the department from a single professor, William Waggener, to a world-class program culminating with our first Nobel laureates Carl Wieman and Eric Cornell.

Jack married Nancy Whiting Curtis, also a physicist, in 1951. Both were from New Jersey. They have three sons Jeffrey, Steven and Matthew, and four grandchildren.

Jack’s family requests that friends make donations to the American Friends Service Committee (, 901 W 14th Ave # 7, Denver, CO 80204.