Rachel L. (Mazie) Vorkink, 69, a retired chief of the technical reports branch of the Army's Harry Diamond Laboratories, died of cancer Feb. 20 at her home in Silver Spring.

A physicist by training, she came to Washington in 1942 and joined the National Bureau of Standards. She was a member of a group testing military ordnance and later became involved in writing and editing technical reports.

She did similar work when the ordnance division of the National Bureau of Standards was transferred to the Army, where it was conducted at the Diamond Ordnance Fuze Laboratories. This name later was changed to the Harry Diamond Laboratories. Mrs. Vorkink was chief of its technical reports branch at the time she retired in 1970.

She was born in Newbury, Mass. She was a Phi Beta Kappa graduate of Oberlin College in Ohio and later returned there to do graduate work in physics. She also did graduate work at the University of Maine and at the University of California at Lost Angeles.

Mrs. Vorkink's hobbies included hydropine racing. In the 1940s and 1950s she piloted her small outboard hydroplane, "Ugly Chile," in many races along the East Coast. She also was fond of jazz.

Her marriages to Harry Vorkink, of Santa Monica, Calif., and to Dean Worcester, of Silver Spring, both ended in divorce.

Survivors include two sisters, Marjorie R. Dowling, of Allentown, Pa., And edith M. Rogers of Baltimore.