A lotta neutrino detectors work by looking for the flares ‘n’ flashes of light generated on the rare occasion a neutrino smashes into something solid, like an atom.  Ya need to do a lotta lookin’ though, which is why neutrino detectors sit in vast pools of water or are dropped into the oceans or buried in ancient Antarctic ice.

Now Jonathan Perkin, a  fresh-faced physicist at the University of Sheffield suggests that it might also be possible to listen for the sound that neutrinos make when they whizz through water. The thinkin is that an ultra high energy neutrino smashing into an atom rapidly raises the temperature of the water nearby producing an acoustic pulse which could be picked up by an off-the-shelf hydrophone.

Neat idea, except that Perkin goes on to to say that to have a realistic chance of picking up the sound of neutrinos you’d need a detector that is over a thousand cubic kilometres in size with over 100 hydrophones in each cubic kilometre. That’s big enough to be a nonstarter in most people’s books.

Where neutrino noise might turn out to be useful, however, is for filtering data from the big neutrino telescopes such as IceCube under the South Pole.

Pick up both the light and sound signatures of a neutrino hit and that’s pretty good evidence that it ain’t no false alarm. So the sound of neutrinos zipping past might turn out to be useful after all.

Ref: arxiv.org/abs/0801.0991: The Acoustic Detection of Ultra High Energy Neutrinos

The next generation of chips are gonna need some major coolin’, perhaps as much as 1000 Watts of cold per square centimetre. We’re talkin’ high-speed microprocessors, optoelectronics, micro- and millimeter-wave power electronics and power conditioning transistors for electronic motor control in hybrid vehicles power converters etc. These are machines that will generate significant heat.

Ordinary coolin fans ain’t gonna work for those kindsa fluxes so alotta engineers have been thinkin’ about phase change systems in which a liquid absorbs heat, boils into a gas and carries the energy away.

The trouble is that  a vapor layer tends to form over the surface of a chip and this acts as an insulator preventing further heat transfer.

So Ari Glezer and pals at the Georgia Institue of Technology in Atlanta have come up with a way of dislodging the vapor by bombarding it with sound. It’s just a pump for pushing the liquid round with a piezovibrator to create an acoustic field.

They reckon it works well and at relatively low power. In their set up, they achieve a colling rate of 165W per square cm. But with acoustic zapping they can raise this to 338 W per square cm. That’s an improvement of 150%.

Ref: arxiv.org/abs/0801.0785: Acoustically Enhanced Boiling Heat Transfer