File:U.S. Department of Energy - Science - 278 002 006 (16517741921).jpg

DR JAY PETERSEN ADJUSTS THE LARGE GONI-OMETER INSTALLED IN A SPECIALLY SHIELDED CAVE OF THE A W WRIGHT NUCLEAR - YALE.

THE CAVE IS UNDER 20 FEET OF EARTH AND HAS 3 FOOT WALLS, FLOOR AND CEILING OF A SPECIAL CONCRETE CONTAINING NONE OF THE COMMON NATURALLY RADIOACTIVE SUBSTANCES (E.G. THORIUM AND POTASSIUM) SO THAT THE NORMAL RADIATION BACKGROUND LEVEL IS LESS THAN ONE THOUSANDTH OF THAT IN A TYPICAL RESIDENCE. THE PROJECTILE BEAM FROM THE ACCELERATOR ENTERS FROM THE RIGHT, AND PASSES THROUGH THE TARGET UNDER STUDY IN THE CENTRAL HEMISPHERICAL CHAMBER BEFORE EXITING TO THE LOWER LEFT AND BEING STOPPED IN AN UNDERGROUND BEAM DUMP OUTSIDE OF THE CAVE. ONE OF THE LARGE, COMPUTER CONTROLLED GAMMA RADIATION DETECTORS IS SHOWN ON ITS OVERHEAD MOUNT TO THE LEFT OF DR. PETERSEN, A NUMBER OF SUCH DETECTORS MAY BE USED SIMULTANEOUSLY UNDER ON-LINE COMPUTER CONTROL IN THE MEASUREMENT OF CHARACTERISTIC RADIATION PATTERNS FROM THE TARGET NUCLEI UNDER STUDY FOLLOWING THEIR STIMULATION BY THE PROJECTILES IN THE BEAM.