The Bureau shall provide diagnostic facilities to make social, medical, psychological and other appropriate studies of persons committed to its care. At the request of any sentencing court, and in accordance with standards established by the Bureau, diagnostic services shall be provided for any person who has been convicted, is before the court for sentencing, and is subject to commitment to the Bureau. A report of the findings shall be furnished to the court. To the maximum extent feasible, diagnostic services shall be made available in community-based institutions.