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BOSS Quasars Unveil a New Era in the Expansion History of the Universe

By Guest PostNovember 21, 2012Scienceacceleration, analytic techniques, ancient universe, andreu font ribera, apache point observatory, bao, baryon, baryon acoustic oscillations, berkeley lab, bigboss, bill carithers, BOSS, clouds, cosmology, dark energy, dark matter, data sets, david schlegel, deceleration, density variation, digital sky survey, early universe, evolution, expanse of sky, expansion, gas clouds, gas density, gravity, hydrogen absorption lines, intergalactic gas, lyman alpha forest, mocks, new mexico, nicholas ross, oscillation, patrick mcdonald, quasars, riemann linux cluster, sdss, sloan, Space, spectra, spectroscopic, survey, universe, volume

Berkeley Lab scientists and their Sloan Digital Sky Survey colleagues use quasars to probe dark energy over 10 billion years in the past

BOSS, the Baryon Oscillation Spectroscopic Survey, is mapping a huge volume of space to measure the role of dark energy in the evolution of the universe. BOSS is the largest program of the third Sloan Digital Sky Survey (SDSS-III) and has just announced the first major result of a new mapping technique, based on the spectra of over 48,000 quasars with redshifts up to 3.5, meaning that light left these active galaxies up to 11.5 billion years in the past.

“No technique for dark energy research has been able to probe this ancient era before, a time when matter was still dense enough for gravity to slow the expansion of the universe, and the influence of dark energy hadn’t yet been felt,” says BOSS principal investigator David Schlegel, an astrophysicist in the Physics Division of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). “In our own time, expansion is accelerating because the universe is dominated by dark energy. How dark energy effected the transition from deceleration to acceleration is one of the most challenging questions in cosmology.” (more…)

Anti-Helium Discovered in the Heart of STAR

By Guest PostApril 26, 2011Scienceaccelerator technology, alpha magnetic spectrometer, ams, anti heavy hydrogen, anti hypertriton, antialpha, antideuteron, antielectron, antihelium 4, antinucleons, antiparticles, antiproton, baryon, baryon number, berkeley lab, carl anderson, CERN, collisions of energetic gold nuclei, ernest rutherford, experiment, hans georg ritter, heaviest antiparticle, nu xu, nucleus, nucleus of antihelium 4, nucleus of antihydrogen, particle, positron, relativistic heavy ion collider, rhic, star, star experiment

*Berkeley Lab nuclear scientists join with their international colleagues in the latest record-breaking discovery at RHIC*

Eighteen examples of the heaviest antiparticle ever found, the nucleus of antihelium-4, have been made in the STAR experiment at RHIC, the Relativistic Heavy Ion Collider at the U.S. Department of Energy’s Brookhaven National Laboratory.

“The STAR experiment is uniquely capable of finding antihelium‑4,” says the STAR experiment’s spokesperson, Nu Xu, of the Nuclear Science Division (NSD) at Lawrence Berkeley National Laboratory (Berkeley Lab). “STAR already holds the record for massive antiparticles, last year having identified the anti-hypertriton, which contains three constituent antiparticles. With four antinucleons, antihelium-4 is produced at a rate a thousand times lower yet. To identify the 18 examples required sifting through the debris of a billion gold-gold collisions.” (more…)

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BOSS Quasars Unveil a New Era in the Expansion History of the Universe

Anti-Helium Discovered in the Heart of STAR