The collection covers almost all aspects of Mitchell's career. Correspondence, biographical items, his work in the Department of Therapeutics/Radiotherapeutic Centre, lecture and broadcast notes, academic and medical societies, research funding, faculty papers, medical school files, notebooks and bibliographical references, research at the Colloid Science Laboratory, and research into the biochemistry of ionising radiations are all well represented. So too is Mitchell's principal research activity: his continuing efforts to find a cure for cancer.
Section A: Biographical
Mitchell's own biographical records of his career, with family and personal correspondence. The section includes summaries by Mitchell of his research activities, and an album used for newspaper cuttings and other memorabilia relating to the Radiotherapeutic Centre and Department of Radiotherapeutics.
Section B: Cambridge
The largest part of the collection, divided into four subsections: (1) The Department of Radiotherapeutics/Radiotherapeutic Centre - the establishment and general administration, accommodation, staffing and equipment, the funding of Mitchell's research, and the future of the Department after his retirement in 1976; (2) Addenbrooke's Hospital - Mitchell's wide-ranging involvement in hospital affairs; (3) University of Cambridge - Mitchell's Faculty Board of Medicine/Faculty Board of Clinical Medicine papers and his extensive Medical School files, which document the development of the Postgraduate Medical Centre, as well as the documentation of miscellaneous university boards, committees, departments, colleges and societies, and Mitchell's university examining; (4) Lectures - Mitchell's departmental lectures and documentation of courses and symposia for general medical practitioners and medical students, organised in conjunction with the hospital and Medical School.
Section C: Notebooks
Research notes, bibliographical notes, notes taken during visits and conferences, and other material. The notes include Mitchell's research notebooks, 1926-1981, which contain substantial additional related material, such as correspondence, reprints, photographs, figures and graphs, and manuscript and typescript notes.
Section D: Research
Material documenting all aspects of Mitchell's research, other than that recorded in his notebooks, running up to his final clinical research project in 1985. There are three subsections: Mitchell's early (1930s) research; his research into the biochemistry of ionising radiations, particularly with reference to the health risks involved (mainly 1941-1949); and his efforts to find a cure for cancer (the largest subsection).
Section E: Publications, lectures and broadcasts
Material for Mitchell's published papers, public lectures and broadcasts. There are also drafts, background material and correspondence relating to the planned book 'Principles in Radiotherapeutic Oncology', which was started but never completed.
Section F: Societies and organisations
Material documenting Mitchell's association with 38 British, overseas and international organisations. The organisation for which there is most material is the Medical Research Council. There is also comprehensive documentation of the establishment of the Anglo-German Medical Society. Other societies and organisations represented include the International Union Against Cancer, the Ministries of Health and Supply, and the World Health Organisation.
Section G: Visits and conferences
Material relating to Mitchell's engagements in the U.K. and abroad, 1946-1986, including his attendance at the first four United Nations Conferences on the Peaceful Use of Atomic Power (1955, 1958, 1964 and 1971), and his many visits to Germany.
Section H: Correspondence
Correspondence files arranged alphabetically, and subsections of shorter scientific correspondence arranged chronologically. The principal alphabetical sequence includes extended exchanges with friends, colleagues and former students. There is also correspondence and lecture material of C.L. Smith, assistant director of research in the Radiotherapeutic Centre.