Radioactive isotopes curie

The first radioactive isotopes to be made in the laboratory were prepared in 1934 by Irene Curie and her husband, Frederic Joliot They achieved this by bombarding certain stable isotopes with high-energy alpha particles. One reaction was... 

Isotope (Curie Symbol) Mode of Decay Half-life Major Radioactive Emissions Energies (MeV)... 

The curie unit (Ci) is based on the activity of 1 g of pure radium-226, which undergoes 3.7 X 1010 transformations per second. It is therefore defined as the quantity of a radioactive isotope which gives 3.7 X 1010 disintegrations per second. The SI unit of activity is the becquerel (Bq), which is equal to one nuclear transformation per second. Hence ... 

In 1898 there was discovered an element, radium, which con tinually and spontaneously emits light, heat, and other radiations. Investigation of these astonishing phenomena by the Curies and others revealed more than forty interrelated radioactive elements which, like radium, are unstable. They do not, however, occupy forty places in the periodic system, but are crowded into twelve places. The explanation for the existence of these numerous so-called radioactive isotopes and their genealogical descent from uranium and thorium were discovered independently by K. Fajans, F. Soddy, A. S. Russell, and A. Fleck. Since the original literature on the radioactive elements embraces such a vast field of research, the following account of their discovery is necessarily far from complete. 

Sometimes the nucleus can be changed by bombarding it with another type of particle. This is referred to as induced radioactivity. In 1934, Irene Curie, the daughter of Pierre and Marie Curie, and her husband, Frederic Joliot, announced the first synthesis of an artificial radioactive isotope. They bombarded a thin piece of aluminum foil with ot-particles produced by the decay of polonium and found that the aluminum target became radioactive. Chemical analysis showed that the product of this reaction was an isotope of phosphorus. 

The Bq is a minute measure of radioactivity and any sizeable amount of radioactive material will contain very many atoms and thus emit considerable amounts (TBq or GBq) of radiation. Another popular unit of decay is the curie, a non-Sl unit (historically calculated from the disintegrations of radium) which is equivalent to 37 x 10 Bq. Importantly, radioactivity decays exponentially, where a population of atoms in a sample will have a characteristic half-life (fi/2). The half-life is the key parameter when considering radioactivity and associated safety of radioisotopes, where fi/2 represents the time taken for the radioactivity to fall to a half the recorded level, as illustrated in Figure 10.4. Half-lives and associated properties of common radioactive isotopes are given in Table 10.2. 

Becquerel s discovery led other researchers, including Marie and Pierre Curie, to discover and study new radioactive elements. Many radioactive isotopes, or radioisotopes, now have important medical, agricultural, and industrial uses. 

The understanding of radioactivity has grown rapidly in the 100 years since its discovery. When the Curies worked with radioisotopes, they did not realize how harmful such materials could be. Marie Curie died of leukemia that was probably caused by her years of contact with radioisotopes. Many more radioactive isotopes exist than the few studied by the Curies. In fact, most of the roughly 2000 known isotopes of all elements are unstable and rmdergo nuclear decay. Fortrmately, most of those do not occur naturally, but are produced synthetically. Your surroundings contain mostly stable isotopes of the common elements, so you are not normally exposed to enough radiation to do you much harm. 

In Germany in 1938, Otto Hahn and Fritz Strassmann, skeptical of claims by Enrico Fermi and Irene Johot-Curie that bombardment of uranium by neutrons produced new so-called transuranic elements (elements beyond uranium), repeated these experiments and chemically isolated a radioactive isotope of barium. Unable to interpret these findings, Hahn asked Lise Meitner, a physicist and former colleague, to propose an explanation for his observations. Meitner and her nephew, Otto Frisch, showed that it was possible for the uranium nucleus to be spfit into two smaller nuclei by the neutrons, a process that they termed fission. The discovery of nuclear fission eventually led to the development of nuclear weapons and, after World War II, the advent of nuclear power to generate electricity. Nuclear chemists were involved in the chemical purification of plutonium obtained from uranium targets that had been irradiated in reactors. They also developed chemical separation techniques to isolate radioactive isotopes for industrial and medical uses from the fission products wastes associated with plutonium production for weapons. Today, many of these same chemical separation techniques are being used by nuclear chemists to clean up radioactive wastes resulting from the fifty-year production of nuclear weapons and to treat wastes derived from the production of nuclear power. 

Radioactive isotopes for tracer studies may be prepared artificially from nonradioactive elements by bombarding them with suitable nuclear particles produced in a cyclotron or a nuclear reactor. The discovery of this effect was made in 1934 by the French physicists Irene Joliot-Curie (1897-1956) and her husband Frederic Joliot-Curie (1900-1958). They were studying the effect of bombarding light elements such as aluminum with alpha (a) particles, which are beams of helium nuclei, fHe. They noticed that, after the bombardment had ceased, a new form of radiation continued to be emitted, and they concluded that a new isotope had been formed. In the case of the bombardment of ordinary aluminum, HAl, with a particles, the product is an isotopic form of phosphorus, ifP, the most abundant isotope of phosphorus being f P. The process is... 

A number of special units and technical terms are used in work with radioactive isotopes. The old unit for the amount of an isotope was the curie (symbol Ci), which is defined as the amount producing exactly 3.7 x 10 ° disintegrations per second. In the preceding example, we have seen that this is approximately the number of disintegrations produced per second by 1 gram of radium. In 1975 the curie was replaced by the becquerel (Bq) which is defined as the amount of radioactive substance giving one disintegration per second. Thus 1 Bq = 1 s and 1 Ci = 3.7 x 10 ° Bq. 

The specific activity of a preparation can be defined as the number of becquerels or curies of the radioactive isotope divided by the total mass of the element present. For example, if carbon is enriched with the radioactive isotope gC, the specific activity was formerly expressed as... 

We have seen that the fundamental unit for the amount of a radioactive isotope is the becquerel or the curie, which are measures of the number of disintegrations per second. For the assessment of the biological effects of high-energy radiation, such as that emitted by radioactive substances, we obviously need another kind of unit. There are several in common use. 

Radiation Power Rate. For sources consisting of a known weight of a single radioisotope whose decay properties are known, the power in Mev/g-sec can be computed from Eq. (10-14) or (10-16). Conversion to watts is then made on the basis that 1 Mev/sec = 1.6 X 10 watt. The addition of other radioisotopes to the volume source requires a summation of the power value calculated for each isotope as described. The power liberation from a complex mixture of radioisotopes such as found in the fission products of U fuel is time-consuming to calculate. Figure 10-7 avoids the necessity of this by giving the and y power, curies and composition of the radioactive isotopes, all as a function of elapsed time after the fuel is pulled from the reactor. This elapsed time is known as the radiation cooling period. 

Radioanalytical chemistry was first developed by Mme. M. Curie, with contributions by many other distinguished researchers, notably E. Rutherford and F. Soddy. These pioneers performed chemical separations and radiation measurements on terrestrial radioactive substances during the 20 years following 1897 and in the process created the very concept of radionuclides. Their investigations defined the three major radiation types, confirmed the emission of these radiations by the nucleus and the associated atomic transformations, established the periodic table between bismuth and uranium, and demonstrated the distinction between stable and radioactive isotopes. 

The Joliot-Curies had produced the first case of artificial radioactivity. Since 1934 over a thousand isotopes not occurring in nature have been formed, and every one of them is radioactive. Every element possesses one or more radioactive isotopes. Even... 

The activity of a quantity of radioactive isotope is defined as the number of disintegrations per second which occur. The usual units are the curie (Ci), which is defined as 3.7 x 10 dps, and the becquerel (Bq), defined as 1 dps. Specific activity for a given isotope is defined as activity per unit mass of the isotope. 

Marie Curie s Radium Institute at the east end of the Rue Pierre Curie in the Latin Quarter, built just before the war with funds from the French government and the Pasteur Foundation, had the advantage in any studies that required polonium. Radon gas decays over time to three only mildly radioactive isotopes lead 210, bismuth 210 and polonium 210, which thus become available for chemical separation. Medical doctors throughout the world then used radon sealed into glass ampules— seeds —for cancer treatment. When the radon decayed, which it did in a matter of days, the seeds no longer served. Many physicians sent them on to Paris as a tribute to the woman who discovered radium. They accumulated to the world s largest source of polonium. 

Pierre and Marie Curie with their daughter, Irene. Irene grew up to continue the study of radioactivity with her husband, Frederic JoUoL Together, Irene and Frederic won a Nobel Prize in 1935 for production of the first artificial radioactive isotope. 

Curie kyur-( )e [Marie Pierre Curie] (1910) n. Unit for measuring radioactivity. One Curie is the quantity of any radioactive isotope undergoing 3.7 x 10 dis/s. 

The availability of neutron sources opened the way to the production of radioactive isotopes of most elements and, in fact, practically all the elements of the periodic system were exposed to neutrons within the following years. This was mainly done in three locations Rome by Fermi and coworkers, Paris by the Curies and coworkers and, a little later in Berlin by Hahn, Meitner, and Strassmann. 

Before 1934, the study of radioactivity was limited to reactions of the relatively few radioisotopes found in nature. In that year, Irene and Frederic Joliot-Curie, French physical chemists, found that radioactivity could be induced in nonradioactive nuclei by bombarding them with small, subatomic particles. They produced an artificial radioactive isotope, nitrogen-13, by bombarding boron-10 with alpha particles from a natural radioisotope ... 

A common problem is, however, the content of the radioactive element radium, which is a common impurity in many phosphorite deposits and which is carried forward to the products. This problem makes phosphogypsum particularly unacceptable for making constmction materials. The latter specifies less than 25 picocurie (a curie is a unit of radioactivity equal to the amount of a radioactive isotope that decays at the rate of 37 billion disintegrations per second) of radioactivity in the phosphogypsum. 

Normally in radiotracer experiments the radioactive isotope is added mixed up with the stable isotope. It therefore becomes necesseuy to express the quantity of radioisotope present per unit mass. This is known zis the specific activity and may be expressed as (i) disintegration rate (ds or d min ), (iQ covmt rate (ct s or ct min ), or (itO curies (mCi or pCi) per unit mass of the mixture (pCi or mCl/mole or gram). 

In 1933, a nuclear bombardment reaction was used to produce the first artificial radioactive isotope. Irene and Frederic Joliot-Curie found that aluminum bombarded with alpha particles produces phosphorus-30, which decays by enutting positrons. The... 

As an example, suppose you wish to obtain the volume of water in a tank but are unable to drain the tank. You add 100 mL of water containing a radioactive isotope. After allowing this to mix completely with the water in the tank, you withdraw 100 mL of solution from the tank. You find that the activity of this solution in curies is 1/1000 that of the original radioactive solution. The isotope has been diluted by a factor of 1000, so the volume of the tank is 1000 X 100 mL = 100,000 mL (100 L). 

In the emission of a j8-particle, the mass number of the radioactive isotope and the product isotope are the same. The product isotope has an atomic number greater by one than the radioactive isotope, an increase of one proton. Po is the symbol that corresponds to atomic number 84. The element is polonium, the other element discovered by the Curies in their investigation of radioactivity. The name of the element was selected to honor Madame Curie s native Poland. 

---