Inventor Howard O. McMahon, a former head of Arthur D. Little Inc., has died at the age of 75. McMahon, who lived in Cambridge, died of heart disease Sunday at Mount Auburn Hospital, said an Arthur D. Little spokesman. The Cambridge-based firm specializes in international management and technology consulting. McMahon joined Arthur D. Little as a research associate in 1943. He succeeded Gen. James M. Gavin as its president in 1964. In 1951 the scientist received the Franklin Institute's Edward Longstreth Medal for co-developing the Collins helium cryostat, which liquefies helium gas at minus 452 degrees Fahrenheit. The American Ceramics Society gave McMahon the Frank Forrest Award in 1952 for his research in thermal radiation. In 1979, he received the Samuel C. Collins Award from the Cryogenic Engineering Conference. McMahon earned a doctorate in physical chemistry and physics from the Massachusetts Institute of Technology. While still an undergraduate, a Canadian neon sign company paid him $100 for his patent on a bubbling Christmas tree candle. After becoming president of Arthur D. Little, McMahon began to organize programs at the American Academy for the Advancement of Science in which the public, scientists and students discussed political and social issues. McMahon also began pushing corporations to conduct social audits, essentially the costs to their employees, customers and the community at large of their doing business. After retiring from Arthur D. Little in 1977, McMahon founded the Helix Technology Corp., which manufactures cryogenic refrigeration systems in Waltham.
