RADIATION STANDARDS, INCLUDING FALLOUT 3 lion per second (3.7 X10 ?°.disintegrations per second). Note that the curie tells nothing about the mass of material involved. To illustrate: 1 curie of uranium 238 weighs about 3 tons while 1 curie of strontium 90 weighs less than one-thousandth of an ounce. A homely analogy may help to understand whatthe strength of a radioactive source in curies tells about the source. When a pan of popcorn has been heated and begins to pop fairly steadily, one could count the number of pops per second and thus determine the rate at which the kernels of corn are disintegrating. The rate of popping corresponds to the amount of radioactivity in curies, and does not alone tell anything about how many ounces of unpopped corn there maybein the pan at the moment. : Multiples of the curie are used for convenience, such as the millicurie, the microcurie, and so forth. Concentrations of radioactive materials in air, water, and other materials are expressed in such units as microcuries per milliliter and microcuries per gram. Representative Price. Dr. Whipple, Mr. Ramey has a question he wants to ask. Mr. Ramey. Could you define a little further what a millicurie is and a microcurie? Dr. Wureriz. A curie is 37 billion disintegrations per second, and a millicurie is one-thousandthof this. Mr. Ramey. That is what always got me mixed up because you would think that millicurie isa million and it isa thousand. EepeepsDBentlasaHdQTHRASEDEINedGHARgayACTERMRSSTa Dr. Wurerte. I think this is faithful to the original Greek that 1 milli means 1,000; micro means1 million. Mr. Ramey. I didn’t take Greek. Dr. Wuirrze. I didn’t take Greek either. Mr. Ramuy. Then what is a micro-micro curie? Dr. Wurprtr. A micro-microcurie would be a millionth of a millionth of a curie. Mr. Ramey. And weuse that term quite a bit in our measurement units. So it isa very small amount of radiation weare talking about. Dr. Wurtz. Exceedingly small. Senator AnpErson. You have me off on another subject. I wonder if the rate of the disintegrations of popcorn had anything to do with how much butterisin it. Dr. Wutpriz. I am afraid I have to stop my analogy on the popping. _. (6) The roentgen: The oldest unit of radiation dose is the roentgen. It 1s defined in terms of the amountof ionization produced in a given volume of air by X or y radiation. Strictly speaking the roentgen cannot be used to express the dose of « or 8 particles. “The full practical and theoretical implications of the roentgen are not easily grasped,at least. by our graduate students, so I shall give only a simple description of what the roentgen tells us, knowing that 1f I misrepresent it in any serious way, Dr. Taylor will set you, me, and the record straight. Here again a simple analogy will prove helpful. When a physician prescribes a dose of some drug, say 10 grains of aspirim,he specifies the dose to be taken by his patient. A fraction of the dose will be absorbed by the body and the remainder will be excreted. Only that fraction absorbed has any effect on the patient. The physician, know- roy