Physics

Scientists from the Universities of Liverpool and Glasgow have completed work on the inner heart of an experiment which seeks to find out what has happened to all the antimatter created at the start of the Universe. Matter and antimatter were created in equal amounts in the Big Bang but somehow the antimatter disappeared resulting in the Universe, and everything in it, including ourselves, being made of the remaining matter.

The first sector of CERN* 's Large Hadron Collider (LHC) to be cooled down has reached a temperature of 1.9 K (-271°C), colder than deep outer space! Although just one-eighth of the LHC ring, this sector is the world's largest superconducting installation. The entire 27-kilometre LHC ring needs to be cooled down to this temperature in order for the superconducting magnets that guide and focus the proton beams to remain in a superconductive state. Such a state allows the current to flow without resistance, creating a dense, powerful magnetic field in relatively small magnets. Guiding the two proton beams as they travel at nearly the speed of light, curving around the accelerator ring and focusing them at the collision points is no easy task.

Using a laser-cooling technique that could one day allow scientists to observe quantum behavior in large objects, MIT researchers have cooled a coin-sized object to within one degree of absolute zero.

This study marks the coldest temperature ever reached by laser-cooling of an object of that size, and the technique holds promise that it will experimentally confirm, for the first time, that large objects obey the laws of quantum mechanics just as atoms do.


MIT researchers have developed a technique to cool this dime-sized mirror (small circle suspended in the center of large metal ring) to within one degree of absolute zero. Photo / Christopher Wipf

Livermore researchers have moved one step closer to being able to turn on and off the decay of a nuclear isomer.

The protons and neutrons in a nucleus can be arranged in many ways. The arrangement with the lowest energy is called the ground state and all others are called excited states. (This is analogous to the ground and excited states of electrons in an atom except that nuclear excited states are typically thousands of times higher in energy.) Excited nuclear states eventually decay to the ground state via gamma emission or to another nucleus via particle emission. Most excited states are short-lived (e.g., billionth of a second). However, a few are long-lived (e.g., hours) and are called isomers.

The last quadripolar magnet was brought down into the tunnel of the world’s largest particle accelerator; the CERN’s1 LHC, or Large Hadron Collidor. This magnet is part of a series of 392 units which will ensure that the beams are kept on track all along their trajectory through the tunnel. Its installation marks the completion of a long and fruitful collaboration between the CERN, the CNRS/IN2P32 and the CEA/DSM3 in the field of superconductivity and advanced cryogenics. This collaboration has lasted over ten years and was part of the special contribution made by France, as the host country, to the construction of the LHC.

Using measurements of the four ESA's Cluster satellites, a study published this week in Nature Physics shows pioneering experimental evidence of magnetic reconnection also in turbulent 'plasma' around Earth.


This image provides a model of magnetic fields at the Sun's surface using SOHO data, showing irregular magnetic fields (the ‘magnetic carpet’) in the solar corona (top layer of the Sun's atmosphere). Small-scale current sheets are likely to form in such turbulent environment and reconnection may occur in similar fashion as in Earth's magnetosheath. Credits: Stanford-Lockheed Inst. for Space Research/NASA GSFC

Nanomechanical oscillators -- tiny strips of vibrating silicon only a few hundred atoms thick -- are the subject of extensive study by nanotechnology researchers. They could someday replace bulky quartz crystals in electronic circuits or be used to detect and identify bacteria and viruses.

The catch is that measuring their vibrations isn't easy. It is usually done by bouncing laser beams off them -- which won't work when the nanodevices become smaller than the wavelength of the light -- or with piezoelectric devices -- those bulky quartz crystals we're trying to get rid of.


Schematic of the experimental setup.

Researchers in Japan have developed a pair of molecular-scale scissors that open and close in response to light. The tiny scissors are the first example of a molecular machine capable of mechanically manipulating molecules by using light, the scientists say.

The scissors measure just three nanometers in length, small enough to deliver drugs into cells or manipulate genes and other biological molecules, says principal investigator Takuzo Aida, Ph.D., professor of chemistry and biotechnology at the University of Tokyo.


The scissors-like molecular machine extends or folds in response to different wavelengths of light. Credit: University of Tokyo.

As an electromagnetics guy I stay in touch with a lot of what is happening in that segment of physics by subscribing to plain, ol' email lists. People who need info just fire off a question to the group and someone helps.

Occasionally recruiters spam the place because, you know, all of their recruiting emails are terribly important to the whole planet. When I got my email this morning, I saw this:

University of Chicago scientists will demonstrate how to incinerate a white dwarf star in unprecedented detail at the “Paths to Exploding Stars” conference on Thursday, March 22, in Santa Barbara, Calif.

White dwarf stars pack one and a half times the mass of the sun into an object the size of Earth. When they burn out, the ensuing explosion produces a type of supernova that astrophysicists believe manufactures most of the iron in the universe.