Raymond Andrew Sorensen, a theoretical nuclear physicist and former chairman of Carnegie Mellon University's physics department, died March 13 of heart failure. He was 74.

For the past four years, Mr. Sorensen had lived in Shingle Springs, Calif., a sleepy little town in the foothills of the Sierra Nevada mountain range.

Mr. Sorensen grew up in Wilkinsburg and attended Edgewood High School. After two years at the College of Wooster in Ohio, he transferred to Carnegie Mellon, where he earned a bachelor's degree in 1953 and a doctorate in physics in 1958.

After a year at the Niels Bohr Institute in Copenhagen and two years at Columbia University in New York City, Mr. Sorensen joined the faculty at his alma mater where he worked until his retirement in 1997. Mr. Sorensen did his research in theoretical nuclear physics and had numerous articles published in scientific journals. He taught classes at all levels.

From 1980 through 1989, Mr. Sorensen chaired the department and was highly respected by his colleagues.

"He was a strong advocate of physics, always meticulously prepared and thoroughly honest and trustworthy in his analysis of departmental plans and in administrative matters," said Robert F. Sekerka, who first met Sorensen in 1982 when Sekerka had become dean of the Mellon College of Science.

"I remember him most for his ability to render thoughtful, unbiased and unselfish advice in matters involving the whole college, or more broadly, the university," continued Sekerka, now professor of physics and mathematics. "We owe a debt of gratitude to Ray and his gracious wife, Audrey, for their diligent service to Carnegie Mellon."

After his retirement, Mr. Sorensen and his wife did some traveling, returning to Copenhagen, as well as taking trips to Stockholm and Seattle.

In 2001, he moved to California to be near his daughter. He and wife Audrey, who died unexpectedly in her sleep in 2002, renovated a geodesic dome house and explored the rivers, lakes and mountains in the area. He also found time to go biking, hiking, camping and canoeing.

"He lived a full, independent life up until the end," said Mr. Sorensen's daughter, Lisa Kirsten Sorensen of Sacramento, Calif. "My father and I were very close and it was nice having him near by for the last few years. He loved to be outdoors."

The family suggests donations be made in his name to PKD Foundation, 9221 Ward Parkway, Suite 400, Kansas City, MO 64114.