100px|A disc of californium metal

Californium is the radioactive metallic chemical element with atomic number 98. It was first produced in 1950 by bombarding curium with alpha particles at the University of California, Berkeley. The element was named for California and the University of California. Two crystalline forms exist for californium under normal pressure, and a third exists at high pressure. Compounds of californium are dominated by a chemical form of the element, designated californium(III), that can participate in three chemical bonds. The most stable of californium's twenty known isotopes is californium-251, which has a half-life of 898 years; this short half-life means the element is not found in the Earth's crust. Californium-252, whose half-life is 2.645 years, is the most common isotope used. Californium can be used to help start up nuclear reactors, and is employed as a source of neutrons when studying materials with neutron diffraction and neutron spectroscopy. It can also be used in nuclear synthesis of higher mass elements; ununoctium was synthesized by bombarding californium-249 atoms with calcium-48 ions. Use of californium must take into account radiological concerns and the element's ability to disrupt the formation of red blood cells by bio-accumulating in skeletal tissue. (more...)

Recently featured: Painted turtle – 1949 Ambato earthquake – James Boyd

Archive – By email – More featured articles...

Read the rest of this article: http://en.wikipedia.org/wiki/Californium

_______________________________ Today's selected anniversaries:

365:

A large earthquake that struck near Crete and its subsequent tsunami caused widespread destruction throughout the eastern Mediterranean region. http://en.wikipedia.org/wiki/365_Crete_earthquake

1865:

In one of the few recorded instances of a "quick draw" gun duel in the American Old West, Wild Bill Hickok shot and killed Davis Tutt over a poker debt. http://en.wikipedia.org/wiki/Wild_Bill_Hickok_%E2%80%93_Davis_Tutt_shootout

1954:

First Indochina War: The Vietnamese Demilitarized Zone was established at the Geneva Conference, partitioning Vietnam along the 17th parallel north into two zones: North Vietnam led by Ho Chi Minh and South Vietnam under Bao Dai. http://en.wikipedia.org/wiki/Geneva_Conference_%281954%29

1969:

During the Apollo 11 mission, Neil Armstrong and Buzz Aldrin became the first humans to walk on the Moon. http://en.wikipedia.org/wiki/Neil_Armstrong

1970:

The Aswan High Dam in Egypt was completed after 11 years of construction. http://en.wikipedia.org/wiki/Aswan_Dam

_____________________________ Wiktionary's word of the day:

charlady (n): (chiefly archaic or historical) A woman whose professional occupation is to clean houses; a cleaning-lady http://en.wiktionary.org/wiki/charlady

___________________________ Wikiquote quote of the day:

Today is only one day in all the days that will ever be. But what will happen in all the other days that ever come can depend on what you do today. It's been that way all this year. It's been that way so many times. All of war is that way. --Ernest Hemingway http://en.wikiquote.org/wiki/Ernest_Hemingway