Two American citizens and a Russian won the 2003 Nobel Prize (searchin physics for their work in the bizarre field of quantum physics, the Royal Swedish Academy of Sciences said Tuesday.

Alexei A. Abrikosov, Anthony J. Leggett and Vitaly L. Ginzburg were awarded the prize for their work concerning superconductivity and superfluidity (search).

Abrikosov, 75, is a Russian and American citizen based at the Argonne National Laboratory in Illinois; Ginzburg, 87, is a Russian based at the P.N. Lebedev Physical Institute in Moscow; and Leggett, 65, is a British and American citizen based at the University of Illinois.

Superconducting material is used, as an example, to produce powerful magnetic fields for the standard body scanning technique called magnetic resonance imaging (search), or MRI, the academy said in its citation.

The prize includes a check for 10 million kronor, or $1.3 million, and bestows a deeper sense of academic and medical integrity upon the winners.

Alfred Nobel (search), the wealthy Swedish industrialist and inventor of dynamite who endowed the prizes, left only vague guidelines for the selection committee.

In his will he said the prize revealed Tuesday should be given to those who "shall have conferred the greatest benefit on mankind" and "shall have made the most important discovery or invention within the field of physics."

The academy, which also chooses the chemistry and economics winners, invited nominations from previous recipients and experts in the fields before cutting down its choices.

A Japanese and two American astrophysicists won last year's prize for using some of the most obscure particles and waves in nature to increase understanding of the universe.

Riccardo Giacconi, 71, of the Associated Universities Inc. in Washington, D.C., was cited for his role in "pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources."

Raymond Davis Jr., 87, of the University of Pennsylvania and Japanese scientist Masatoshi Koshiba, 76, of the University of Tokyo, were awarded for their construction of giant underground chambers to detect neutrinos, elusive particles that stream from the sun by the billion.

This year's Nobel awards started last week with the awarding of the Nobel Prize in literature to South Africa author J.M. Coetzee.

On Monday, American Paul C. Lauterbur, 74, and Briton Sir Peter Mansfield, 70, were selected by a committee at the Karolinska Institute for the 2003 Nobel Prize in medicine for discoveries leading to a technique that reveals images of the body's inner organs.

Magnetic resonance imaging, or MRI, has become a routine method for medical diagnosis and treatment. It is used to examine almost all organs without need for surgery, but is especially valuable for detailed examination of the brain and spinal cord.

The winner of the Nobel Prize in chemistry will be named on Wednesday morning and the Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel later the same day.

The winner of the coveted peace prize -- the only one not awarded in Sweden -- will be announced Friday in Oslo, Norway.

The prizes, which include a gold medal and a diploma, are presented on Dec. 10, the anniversary of Nobel's death in 1896, in Stockholm and in Oslo.