| Topic: |
Science > Physics |
| User: |
"current affairs" |
| Date: |
17 Oct 2006 11:39:21 PM |
| Object: |
Element 118 Created- In Mendeelef- Periodic Table |
Story link:
http://www.xdot.in/story/Element-118-Created-In-Mendeelef-Periodic-Table/
American and Russian researchers said yesterday that they had created
element 118, the heaviest known element. Apprently it was added to
periodic table before and then removed and now added again.
.
|
|
| User: "Sam Wormley" |
|
| Title: Re: Element 118 Created- In Mendeelef- Periodic Table |
17 Oct 2006 11:56:04 PM |
|
|
current affairs wrote:
Story link:
http://www.xdot.in/story/Element-118-Created-In-Mendeelef-Periodic-Table/
American and Russian researchers said yesterday that they had created
element 118, the heaviest known element. Apprently it was added to
periodic table before and then removed and now added again.
PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 797 October 16, 2006 by Phillip F. Schewe, Ben Stein,
and Davide Castelvecchi www.aip.org/pnu
ELEMENTS 116 AND 118 ARE DISCOVERED. At the Joint Institute for
Nuclear Research (JINR) in Dubna, Russia, physicists (including
collaborators from Lawrence Livermore National Lab in the US) have
sent a beam of calcium-48 ions into a target of californium-249
atoms to create temporarily a handful of atoms representing element
118. The nucleus for these atoms have a total atomic mass of 294
units. In fact, only three of these atoms, the heaviest ever
produced in a controlled experiment, were observed. After sending 2
x 10^19 calcium projectiles into the target, one atom of element 118
was discovered in the year 2002 and two more atoms in 2005. The
researchers held up publication after seeing their first specimen in
order to find more events. According to Livermore physicist Ken
Moody, speaking at a press conference today from Livermore, the
three events have been well studied and the odds of a statistical
fluke at work here are less than a part in ten thousand. Caution
would naturally be on the minds of anyone announcing a new element;
Evidence for element 118 was offered once before, by a team at the
LBL lab ( http://www.aip.org/pnu/1999/split/pnu432-1.htm), but this
claim was later retracted (www.aip.org/pnu/2001/split/550-1.html)
when it was discovered that some of the data had been falsified.
In searching through 10^19 collision events, how do you know you
have found a new element? Because of the clear and unique decay
sequence involving the offloading of alpha particles, nuclear
parcels consisting of two protons and two neutrons. In this case,
nuclei of element 118 decay to become element 116 (hereby itself
discovered for the first time), and then element 114, and then
element 112 by emitting detectable alphas. The112 nucleus
subsequently fissions into roughly equal-sized daughter particles.
The average lifetime observed for the three examples of element 118
was about one millisecond, not long enough to perform any kind of
chemical tests (you’d need an hour’s time for that). Element 118
lies just beneath radon in the periodic table and is therefore a
kind of noble gas.
The Dubna-Livermore team previously announced the discovery of
elements 113 and 115 (http://www.aip.org/pnu/2004/split/672-1.html)
and next hope to produce element 120 by crashing a beam of iron
atoms into a plutonium target. To build nuclei much heavier than
this you would need a beam of neutron-rich radioactive nuclei; the
proposal to build an accelerator in the US for doing just this has
been stalled. (Oganessian et al., Physical Review C, October 2006;
Livermore press release at www.llnl.gov)
.
|
|
|
| User: "CWatters" |
|
| Title: Re: Element 118 Created- In Mendeelef- Periodic Table |
18 Oct 2006 02:35:00 AM |
|
|
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:DtiZg.199491$FQ1.116662@attbi_s71...
current affairs wrote:
Story link:
http://www.xdot.in/story/Element-118-Created-In-Mendeelef-Periodic-Table/
American and Russian researchers said yesterday that they had created
element 118, the heaviest known element.
It's interesting that new elements these days are created rather than
discovered. Is this new elememt likely to have ever occured in the wild?
Presumably we learn a lot by creating new elements?
.
|
|
|
|
|
|
Related Articles |
|
|
