PHYSICS NEWS UPDATE -- Number 729 April 27, 2005 by Phillip F. Schewe,Ben Stein

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Topic:	Science > Physics
User:	"Sam Wormley"
Date:	27 Apr 2005 01:29:55 PM
Object:	PHYSICS NEWS UPDATE -- Number 729 April 27, 2005 by Phillip F. Schewe,Ben Stein

PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 729 April 27, 2005 by Phillip F. Schewe, Ben Stein

PYROFUSION: A ROOM-TEMPERATURE, PALM-SIZED NUCLEAR FUSION DEVICE has
been reported by a UCLA collaboration, potentially leading to new
kinds of fusion devices and other novel applications such as
microthrusters for MEMS spaceships. The key component of the UCLA
device is a pyroelectric crystal, a class of materials that includes
lithium niobate, an inexpensive solid that is used to filter signals
in cell phones. When heated a pyroelectric crystal polarizes
charge, segregating a significant amount of electric charge near a
surface, leading to a very large electric field there. In turn,
this effect can accelerate electrons to relatively high (keV)
energies (see Update 564,
http://www.aip.org/pnu/2001/split/564-2.html).
The UCLA researchers (Seth Putterman, 310-825-2269) take this idea
and add a few other elements to it. In a vacuum chamber containing
deuterium gas, they place a lithium tantalate (LiTaO3) pyroelectric
crystal so that one of its faces touches a copper disc which itself
is surmounted by a tungsten probe. They cool and then heat the
crystal, which creates an electric potential energy of about 120
kilovolts at its surface. The electric field at the end of the
tungsten probe tip is so high (25 V/nm) that it strips electrons
from nearby deuterium atoms. Repelled by the negatively charged tip,
and crystal field, the resulting deuterium ions then accelerate
towards a solid target of erbium deuteride (ErD2), slamming into it
so hard that some of the deuterium ions fuse with deuterium in the
target. Each deuterium-deuterium fusion reaction creates a helium-3
nucleus and a 2.45 MeV neutron, the latter being collected as
evidence for nuclear fusion. In a typical heating cycle, the
researchers measure a peak of about 900 neutrons per second, about
400 times the "background" of naturally occurring neutrons. During
a heating cycle, which could last from 5 minutes to 8 hours
depending on how fast they heat the crystal, the researchers
estimate that they create approximately 10^-8 joules of fusion
energy. (To provide some perspective, it takes about 1,000 joules
to heat an 8-oz (237 ml) cup of coffee one degree Celsius.) By
using a larger tungsten tip, cooling the crystal to cryogenic
temperatures, and constructing a target containing tritium, the
researchers believe they can scale up the observed neutron
production 1000 times, to more than 10^6 neutrons per second.
(Naranjo, Gimzewski, Putterman, Nature, 28 April 2005). The
experimental setup is strikingly simple: "We can build a tiny
self-contained handheld object which when plunged into ice water
creates fusion," Putterman says.
(http://rodan.physics.ucla.edu/pyrofusion )

NICKEL-78, THE MOST NEUTRON-RICH OF THE DOUBLY-MAGIC NUCLEI, has had
its lifetime measured for the first time, which will help us better
understand how heavy elements are made. Indeed, where do gold atoms
come from? Physicists believe gold and other heavy elements (beyond
iron) were built from lighter atoms inside star explosions billions
of years ago. In the "r-process" (r standing for rapid) unfolding
inside the explosion, a succession of nuclei bulk up on the many
available neutrons. This evolutionary buildup is nicely captured in
a movie simulation showing all the species in the chart of the
nuclides being made one after the other
(http://www.jinaweb.org/html/movies.html). In some models the
buildup can slow down at certain strategic bottlenecks. Nickel-78
is one such roadblock. This is because Ni-78 is a "doubly magic"
nucleus. It has both closed neutron and proton shells; it is
"noble" in a nuclear sense in the way that a noble gas atom is noble
in the chemical sense owing to its completely filled electron
shell. Knowing more about this crucial nuclide is made difficult
by the fact that it is, in our modern era, very rare, and hard to
make artificially. Nevertheless, scientists at the National
Superconducting Cyclotron (NCSL) at Michigan State University have
now culled 11 specimens of Ni-78 from among billions of high-energy
collision events recorded. In effect, the NCSL is a factory for
reproducing supernova conditions here on Earth. Hendrik Schatz
(schatz@ncsl.msu.edu, 517-333-6397), speaking at last week's
American Physical Society meeting in Tampa, reported that from the
available Ni-78 decays recorded, a lifetime of 110 milliseconds
could be deduced. This is some 4 times shorter than previous
theoretical estimates, meaning that the bottleneck nucleus lived
shorter than was thought, which in turn means that the obstacle to
making heavier elements was that much less. So far the exact
conditions and site for the r-process are still unknown. With the
new measurement model conditions have to be readjusted to produce
the observed amounts of precious metals in the universe. This will
provide a better idea of what to look for when searching for the
site of the r-process. (See also Hosmer et al., Physical Review
Letters, 25 March 2005)
***********
PHYSICS NEWS UPDATE is a digest of physics news items arising
from physics meetings, physics journals, newspapers and
magazines, and other news sources. It is provided free of charge
as a way of broadly disseminating information about physics and
physicists. For that reason, you are free to post it, if you like,
where others can read it, providing only that you credit AIP.
Physics News Update appears approximately once a week.
.

User: "Uncle Al"
Title: Re: PHYSICS NEWS UPDATE -- Number 729 April 27, 2005 by Phillip F.Schewe,Ben Stein	27 Apr 2005 04:29:26 PM

Sam Wormley wrote:

[snip]
Rube Goldberg grantology.
Reverse bias a Geiger-Muller tube. Fill with D2 and a trace of CH3Br
as trigger. Add radiation. You get hot fusion at the central
electrode as the postive ion cascade screams down the voltage gradient
and divergence. Nice desktop demo. My idiot government actually
considered that as a tritium generator until a mob of outraged
scientist loudly ran the numbers. Tritium is made by irradiating
lithium-6 alloy in reactor core.
Ditto take a charged heavy water cluster gas phase in vacuum, drop it
down a voltage gradient, and have it hit a deuterium-containing
target. Fusion!
So? It is useless.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf
.

User: "Andy Resnick"
Title: Re: PHYSICS NEWS UPDATE -- Number 729 April 27, 2005 by PhillipF. Schewe, Ben Stein	28 Apr 2005 11:17:49 AM

Sam Wormley wrote:

<snip>

The UCLA researchers (Seth Putterman, 310-825-2269) take this idea

They included Seth's phone number? That's a real disincentive to
publicize research... OTOH, maybe that's a good thing.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.

User: ""
Title: Re: PHYSICS NEWS UPDATE -- Number 729 April 27, 2005 by Phillip F. Schewe, Ben Stein	28 Apr 2005 04:28:58 PM

In article <d4r2be$n4u$1@eeyore.INS.cwru.edu>, Andy Resnick <andy.resnick@op.case.edu> writes:

Sam Wormley wrote:

<snip>

The UCLA researchers (Seth Putterman, 310-825-2269) take this idea

They included Seth's phone number? That's a real disincentive to
publicize research... OTOH, maybe that's a good thing.

In this case, it is probably a good thing. Pure grantmanship.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
.

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