the relative amounts present give a measure of the time that has elapsed since the meteorite solidified so that it could retain argon.

It is striking that this age agrees with the one obtained for the age of the earth's crust. By comparing the relative abundance of lead isotopes in the earth's crust with those in meteorites that contain negligible quantities of uranium, it is possible to determine how long radioactive disintegration of uranium 238 and uranium 235 must have been going on to account for the observed proportions of lead 236 and 237 in the earth's crust. These measurements and calculations give a value of about 4.5 billion years. Both the age of the meteorites and the age of the earth's crust were determined by physicists of the University of Chicago using, in part, the facilities of the Argonne National Laboratory.

UCRL Bevatron

Initial operation of the bevatron at the University of California Radiation Laboratory began in February, when protons were accelerated to an energy of about 5 Bev (billion electron volts). Performance continued to improve, and by April a proton beam energy of 6.1 Bev was attained-the highest energy yet realized with protons. Bombardment of targets with 6 Bev protons is expected to produce an abundance of many particles previously undetected in a laboratory.

There is particular interest in the use of the bevatron to create and study mesons (elementary particles having a mass intermediate between that of an electron and that of a proton). Mesons have been found in a bewildering variety in cosmic rays and have been produced by other high energy accelerators. However, the higher energy from the bevatron is expected to open up a new range in the spectrum of these particles not previously available for laboratory study. Experiments are also planned with protons, neutrons, and mesons using a great many target materials to study their absorption and their scattering.

BNL Cosmotron

During operation of the cosmotron on November 5 at Brookhaven National Laboratory a short circuit developed in the main magnet winding in the southeast quadrant near the south straight section, as a result of a water leak in a cooling tube. It was tentatively estimated that 3 to 6 months shutdown time will be required for repairs. This affords an opportunity for incorporating improvements in the machine, and ejection magnets are being installed to facilitate getting the beam out of the cosmotron, thereby substantially increasing its effectiveness.

BNL Alternating Gradient Synchrotron

Use of the alternating gradient (strong focusing) principle in the synchrotron to be constructed at BNL is expected to permit proton energies of 25 to 35 Bev to be attained-about 10 times those realized in the laboratory's cosmotron. The Brookhaven staff will explore design problems with a smaller-scale experimental device, known as an electron analogue that will accelerate electrons.

ORNL Research Reactor

In August 1954, the AEC authorized the design and construction of a reactor facility at the Oak Ridge National Laboratory, specifically designed to carry out the laboratory's research programs. The reactor installation, designated as the ORR, is a simplified version of the Materials Testing Reactor (MTR) at Idaho Falls, Idaho, and will operate at a power level of 5 megawatts.

The design work is being carried on by ORNL and the McPherson Co. of Greenville, S. C., and is expected to be completed by March 1, 1955. A lump-sum contract will be let for the construction of the building, reactor, and cooling system by February 1, 1955. Operation of the reactor is scheduled by August 1, 1956.

Biology and Medicine

In order to minimize the hazards associated with the use of radioactive materials and to protect against overexposures to radiation, broad research activities in biology and medicine are necessary. Laboratory and field investigations continued in the past 6 months to be projected toward studies of the effects of radiation on living things, understanding the mechanisms by which these effects are produced, and developing controls and methods of protection against damaging effects.

Current progress is reported here on activities which describe the broad scope of this program at research installations. Brief developments are described in the instrumentation field, and recent participation in civil defense activities.

Residents of Marshall Islands

The first medical follow-up study on the Marshallese from the islands of Rongelap and Utirik accidentally exposed to the March 1 detonation was completed recently. In September the AEC arranged to have the study made by a team from the technical staffs of the Naval

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Radiological Defense Laboratory and the Naval Medical Research Institute. The people continue in excellent health. Blood counts are now approximately normal, skin lesions have entirely healed, and a regrowth of hair has occurred.

Radiobiology Conference in Japan

An unclassified scientific conference on radiobiology attended by scientists from Japan and the United States was held November 1520, in Tokyo, Japan. The invitation to participate in this conference was received from the Japanese Science Council. Representatives from the Commission and the Department of Agriculture were selected. to attend.

The agenda covered such items as detection and measurement of radioactivity, decontamination of radioactive substances, movement of fission materials in soils and uptake by plants and animals, and the application and utilization of radioisotopes in agricultural and biological research.

The meeting, an outgrowth of preliminary discussions on marine biology with Japanese scientists early this year, provided an excellent opportunity for the mutual exchange of technical data, and stimulated interest for future cooperation and exchange of information on the general subject of radiobiology.

CIVIL DEFENSE ACTIVITIES

The Commission made arrangements to include a Civil Effects Program in the coming Continental Test Operations at the Nevada Test Site in 1955. Ten specific programs were established under the Civil Effects Test Group of the Continental Test Operation. These programs embrace 44 individual experimental and training projects involving participation of various AEC research groups, Federal Civil Defense Administration, Housing and Home Finance Agency, Public Buildings Service, Food and Drug Administration, and the Department of Agriculture.

During the current period assistance to FCDA was given also in the following area: approximately 270 weapons test reports (primarily classified) were transmitted to date since the start of the cooperative program of AEC and the Department of Defense to furnish specific categories of effects information relevant to civil defense planning and operations; in cooperation with the U. S. Weather Bureau, a number of briefings and conferences were arranged to consider the problem of radioactive fall-out; and cobalt 60 radiation sources were