Piezomagnetic Material Changes Magnetic Properties When Stretched

Piezoelectric materials, which generate an electric current when compressed or stretched, are familiar and widely used: think of lighters that spark when you press a switch, but also microphones, sensors, motors and all kinds of other devices. Now a group of physicists has found a material with a similar property, but for magnetism. This “piezomagnetic” material changes its magnetic properties when put under mechanical strain.

Magnetic experiment

Top: A piece of BaFe2As2 is stretched while magnetic measurements are taken (the copper wire coil is part of the NMR device). Lower diagram shows atoms in a plane, with black arrows showing how magnetic spins lie in plane and point in opposite directions. Grey arrows show how the magnetic spin of atoms shifts as the material is stretched.

Italian Dark Matter Experiment Completes Run, Sets Stage for Next Experiment

The DarkSide-50 experiment at the Gran Sasso National Laboratory in Italy has completed its experimental run, the research collaboration announced today (Feb. 21). The experiment did not find any potential dark matter particles, but it did demonstrate that the technology could reject “false positive” signals from natural radioactivity or other sources. That will give researchers more confidence in data from the next, larger experiment, DarkSide-20k.

Dark Matter detector

Schematic of the DarkSide-50 detector. The cylinder is filled with liquid argon, which gives off a flash of light when a particle enters the chamber. This light is detected by photomultiplier tubes at top and bottom. (DarkSide-50 collaboration)

Swirling Quark-Gluon Plasma is the Swirliest Fluid Ever

STAR detector at Brookhaven

The Solenoidal Tracker at RHIC (STAR) detector is used to search for signatures of the quark-gluon plasma, a form of matter that filled the early universe. (Brookhaven National Laboratory)

The soup of fundamental particles called the quark-gluon plasma can swirl far faster than any known fluid – faster than the mightiest tornado or the superstorm that is Jupiter’s Great Red Spot.

The results, published Aug. 3 in the journal Nature, come from a new analysis of data from the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory.

Deep Underground Neutrino Experiment Breaks Ground

A special groundbreaking was held today (July 21) deep underground in South Dakota. Scientists, engineers and guests turned the first shovelfuls of the 800,000 tons of rock that will be excavated to build the Long Baseline Neutrino Facility (LBNF) at the Sanford Underground Research Facility. The cavern will house a giant detector for the Deep Underground Neutrino Experiment (DUNE).

The goal of DUNE is to better understand neutrinos and their role in the evolution of the universe, including why our universe is made of matter and not antimatter. DUNE will also be able to detect neutrinos from deep space, emitted by supernovae or black holes.

SNO+ Neutrino Detector Gets Ready For Run

snowaterfill-1

SNO+ neutrino detector being filled with ultrapure water. The detector will search for neutrinos from distant supernovae and nuclear reactors. Credit: SNO+ Collaboration

 

Not a still from a science fiction movie, but the SNO+ neutrino detector being filled with very pure water prior to starting operations. Located over a mile underground in a mine in Ontario, Canada, the SNO+ detector consists of an acrylic sphere 12 meters in diameter filled with 800 tonnes of scintillation fluid, floating in a bath of ultrapure water surrounded by 10,000 photomultiplier tubes that will detect flashes of light from passing neutrinos.

Physics Nobel for topological phase transitions

The 2016 Nobel Prize for Physics will be shared by David Thouless, F. Duncan Haldane and J. Michael Kosterlitz for their work on peculiar states of matter under extreme conditions. The three used advanced mathematics — specifically topology, the study of shapes — to build theoretical models of matter. Their work has practical implications for understanding superconductors, superfluids and thin magnetic films, and ultimately for new types of devices and technologies.

“This year’s Laureates opened the door on an unknown world where matter can assume strange states,” according to the Nobel Prize citation.

LUX Dark Matter Experiment Ends Run, Still No Dark Matter

UC Davis grad student in LUX chamber

UC Davis graduate student Jeremy Mock inspecting the LUX detector before the chamber was filled with water. Credit: Matt Kapust/Sanford Lab

The Large Underground Xenon (LUX) dark matter experiment, which operates beneath a mile of rock at the Sanford Underground Research Facility in the Black Hills of South Dakota, has completed its silent search for the missing matter of the universe.

The experiment did not find a dark matter particle, but it did eliminate a wide swath of mass ranges where a Weakly Interacting Massive Particle, or WIMP, the leading theoretical candidate for dark matter, might exist, team members said.

A conversation with Freeman Dyson

Thinker, physicist and author Freeman Dyson spent two weeks at the end of October, 2008 on the UC Davis campus. His visit was sponsored by the Department of Physics as part of their Centennial Speaker Series.

Dyson was born in England and served as a researcher for the British Royal Air Force Bomber Command during the Second World War. In 1947, he moved to the U.S. and was a professor of physics at Cornell University and then at the Institute of Advanced Study at Princeton, where he is now professor emeritus. He is the author of several popular books about science and the future, including Disturbing the Universe, Weapons and Hope, Origins of Life, Infinite in All Directions, Imagined Worlds, and The Sun, the Genome and the Internet.