Donald Cooksey was a son of George Cooksey from Birmingham, England and Linda Dows from New York.

After High School at the Thacher School in California, Donald Cooksey followed his brother Charlton Cooksey (a physics professor at Yale) and attended Yale and where he too became a physicist specializing in designing and building scientific instruments, especially detectors for measuring sub-atomic particles such as neutron

Neutron

The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...

s. When Ernest O. Lawrence was at Yale during the 1920s, Cooksey and Lawrence became friends. In 1932, after Lawrence had moved to Berkeley, California to set up the Radiation Laboratory there, Lawrence asked Cooksey to come to Berkeley to make detectors for use with Lawrence's cyclotron

Cyclotron

In technology, a cyclotron is a type of particle accelerator. In physics, the cyclotron frequency or gyrofrequency is the frequency of a charged particle moving perpendicularly to the direction of a uniform magnetic field, i.e. a magnetic field of constant magnitude and direction...

s. Cooksey continued to be a close associate of Lawrence and became associate director of the Lawrence Radiation Laboratory

Lawrence Livermore National Laboratory

The Lawrence Livermore National Laboratory , just outside Livermore, California, is a Federally Funded Research and Development Center founded by the University of California in 1952...

 of the University of California at Berkeley.

Donald Cooksey and his wife Milicent Sperry had a son Donald Dows Cooksey (born in 1944) and a daughter Helen Sperry Cooksey(born 1947) who became a surgeon.