Californium radioactivity

A further important property of the two instruments concerns the nature of any ion sources used with them. Magnetic-sector instruments work best with a continuous ion beam produced with an electron ionization or chemical ionization source. Sources that produce pulses of ions, such as with laser desorption or radioactive (Californium) sources, are not compatible with the need for a continuous beam. However, these pulsed sources are ideal for the TOF analyzer because, in such a system, ions of all m/z values must begin their flight to the ion detector at the same instant in... 

Each of the elements has a number of isotopes (2,4), all radioactive and some of which can be obtained in isotopicaHy pure form. More than 200 in number and mosdy synthetic in origin, they are produced by neutron or charged-particle induced transmutations (2,4). The known radioactive isotopes are distributed among the 15 elements approximately as follows actinium and thorium, 25 each protactinium, 20 uranium, neptunium, plutonium, americium, curium, californium, einsteinium, and fermium, 15 each herkelium, mendelevium, nobehum, and lawrencium, 10 each. There is frequently a need for values to be assigned for the atomic weights of the actinide elements. Any precise experimental work would require a value for the isotope or isotopic mixture being used, but where there is a purely formal demand for atomic weights, mass numbers that are chosen on the basis of half-life and availabiUty have customarily been used. A Hst of these is provided in Table 1. 

These elements have all been named for famous scientists or for the places of their creation. For example, americium, berkelium, and californium were named after obvious geographical locations. Nobelium was named for the Nobel Institute, although later study proved it was not really created there. Curium was named for Marie Curie, the discoverer of radium. Einsteinium was named for the famous physicist, Albert Einstein. Fermium and lawrencium were named for Enrico Fermi and Ernest O. Lawrence, who made important discoveries in the field of radioactivity. Mendelevium was named for the discoverer of the periodic chart. 

ISOTOPES There are a total of 21 isotopes of californium. None are found in nature and all are artificially produced and radioactive. Their half-lives range from 45 nanoseconds for californium-246 to 898 years for californium-251, which is its most stable isotope and which decays into curium-247 either though spontaneous fission or by alpha decay. 

Californium is a synthetic radioactive transuranic element of the actinide series. The pure metal form is not found in nature and has not been artificially produced in particle accelerators. However, a few compounds consisting of cahfornium and nonmetals have been formed by nuclear reactions. The most important isotope of cahfornium is Cf-252, which fissions spontaneously while emitting free neutrons. This makes it of some use as a portable neutron source since there are few elements that produce neutrons all by themselves. Most transuranic elements must be placed in a nuclear reactor, must go through a series of decay processes, or must be mixed with other elements in order to give off neutrons. Cf-252 has a half-life of 2.65 years, and just one microgram (0.000001 grams) of the element produces over 170 mhhon neutrons per minute. 

Neither californium nor its compounds are found in nature. All of its isotopes are produced artificially in extremely small amounts, and all of them are extremely radioactive. All of its isotopes are produced by the transmutation from other elements such as berkelium and americium. Following is the nuclear reaction that transmutates californium-250 into cahfornium-252 Cf + (neutron and A, gamma rays) — Cf + (neutron and A, gamma rays) —> Cf. 

Only a few compounds of californium have been prepared. All are extremely radioactive and have not found many common uses. Californium will combine with several nonmetals as follows californium oxide (CfO ), californium trichloride (CfCl), and californium oxychloride (CfOCl). 

Californium s greatest danger is as a biological bone-seeking radioactive element, which can be both a radiation hazard and a useful treatment for bone cancer. If mishandled, all of californium s isotopes and compounds can be a potential radiation poison. 

Symbol Cf atomic number 98 atomic weight 251 (the principal isotope) californium is a transuranium radioactive actinide element electron configuration [Rn]5/i°7s2 valence state +3 most stable isotope Cf, half-life 800 years isotope properties are presented below ... 

Exposure to Cf radiation can cause cancer. Similar to other radioactive elements, californium can accumulate in the skeletal system, causing damage to the red cell forming mechanism. 

Calcium polyphosphate, dissociation and chain length, 4 48 Calcyclin, 46 454-456 Californium, 20 111 availability and price, 31 2 isotopes, 2 201 melting point, 31 6 oxidation state, 2 197 physical properties, 31 36 preparation and purification, 31 5, 7, 12, 33 apparatus, 31 34, 35 purity, 31 3 radioactivity, 31 33 vapor pressure, 31 6 Califomium-252, a-decay, 31 28 Californium oxide, metallothermic reduction, 31 7, 33... 

Among the artificial radioactive elements of which Seaborg was discoverer or co-discoverer are Americium, Curium, Berkelium, Californium, and Scaborgium. 

The thermal neutron sources are radioactive isotopes which emit neutrons, acclerators, and nuclear reactors. The neutrons from the sources are moderated with materials such as paraffin, graphite, water, heavy water or beryllium. Some of the radioisotopes used as sources of thermal neutrons are antimony, polonium, americium curium and californium. The various sources have different half-lives, ranging from days to years. 

Very little is known about the physical and chemical properties of californium. Its melting point has been found to be 1,652°F (900°C) and its density, 15.1 grams per cubic centimeter, about 15 times that of water. It is also very radioactive. One microgram (millionth of a gram) of the element emits about three million neutrons per second. 

All 21 isotopes of californium are radioactive. The most stable isotope is californium-251. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element s name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope. A radioactive isotope is one that breaks apart and gives off some form of radiation. 

The half life of californium-251 is 898 years. The half life of a radioactive element is the time it takes for half of a sample of the element to break down. For instance, in 898 years, only half of a 100-gram sample of californium-251 would remain. After another 898 years, only half of that amount (25 grams) would remain. 

Radioactive materials, such as californium, are hazardous to living cells. As the element s atoms decay, they emit energy and particles that damage or kill the cell. The damaged cells rapidly divide, producing masses called tumors. Cancerous cells can crowd out healthy cells, reduce or stop organ function, and break free to spread through the body. 

Seaborg, Glen T. (1912-1999). An American chemist who won the Nobel Prize for chemistry in 1951 along with McMillan. He did research in nuclear chemistry, physics, and artificial radioactivity. He discovered the elements plutonium, americum, berkelium, californium, einsteinium, fermium, and medelevium with his colleague. He codiscovered numerous isotopes and radioisotopes. His Ph.D. is from the University of California at Berkeley. 

In addition to the Pu-based heart pacemaker already mentioned, lightweight, portable power packs that use radioactive isotopes as fuel have been developed for other uses. Polonium-210, californium-242, and californium-244 have been used in such generators to power instruments for space vehicles and in polar regions. These generators can operate for years with only a small loss of power. 

Some actinides have medical applications for example, radioactive cali-fornium-252 (Cf) is used in cancer therapy. Better results in killing cancer cells have been achieved using this isotope of californium than by using the more traditional X-ray radiation. 

Nuclear or thermal neutron analysis One application uses californium (a radioactive element) to excite explosive material to release gamma rays that can be detected. Another application excites hydrogen in an explosive that releases neutrons that can be detected. Early in development. Has a small footprint. Hydrogen sensors are not effective in moist soil. 

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