New properties of silicon

I won't pretend I know anything about this. I'm hoping someone can reduce it the level of an old tech.

NIST: Using a groundbreaking new technique at the National Institute of Standards and Technology (NIST), an international collaboration led by NIST researchers has revealed previously unrecognized properties of technologically crucial silicon crystals and uncovered new information about an important subatomic particle and a long-theorized fifth force of nature. By aiming subatomic particles known as neutrons at silicon crystals and monitoring the outcome with exquisite sensitivity, the NIST scientists were able to obtain three extraordinary results: the first measurement of a key neutron property in 20 years using a unique method; the highest-precision measurements of the effects of heat-related vibrations in a silicon crystal; and limits on the strength of a possible "fifth force" beyond standard physics theories. In a regular crystal such as silicon, there are many parallel sheets of atoms, each of which forms a plane. Probing different planes with neutrons reveals different aspects of the crystal. The researchers report their findings in the journal Science. To obtain information about crystalline materials at the atomic scale, scientists typically aim a beam of particles (such as X-rays, electrons or neutrons) at the crystal and detect the beam's angles, intensities and patterns as it passes through or ricochets off planes in the crystal's lattice-like atomic geometry. That information is critically important for characterizing the electronic, mechanical and magnetic properties of microchip components and various novel nanomaterials for next-generation applications including quantum computing. A great deal is known already, but continued progress requires increasingly detailed knowledge.

Reply to
Jim Whitby
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The US National Institute of Standards does lots of interesting , demanding and very finicky work.

It sounds as if you have picked up on some neutron diffraction experiment, which has set a new - lower - limit on how powerful the fifth force could be if it actually existed (which it doesn't seem to).

There was some work on a new mass standard that was going to rely on a very nearly perfect sphere of very pure silicon (and a number were made).

This got thrown away when the international standards community latched onto the Kibble balance as the new mass standard, so those very nearly perfect sphere's of silicon may have been repurposed.

Most of what you posted sounds like PR guff designed to make whatever it was sound more significant than it is.

Reply to
Anthony William Sloman

The quote: "heat-related vibrations in a silicon crystal" sounds like it means phonons. My own research back in the 1960s included "phonon- assisted electron tunnelling". The idea was that at low temperatures the quantised phonon energy could add to the electron energy levels and influence the tunnelling through thin insulator films. All great fun and inconclusive, including not yielding a PhD. Nothing about fifth force, though!

Otherwise I agree with Bill...

Reply to
Mike Coon

Neutron interferometers based on large single crystal boules of silicon have been used since the 1980s at least. I remember a Scientific American article about it around 1982 iirc.


Phil Hobbs

Reply to
Phil Hobbs

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