Science: SESAME, the multinational synchrotron light source under construction in the Middle East, is one step closer to being operational by 2015. The European Union has announced that it will invest €5 million ($6.45 million) in magnets to be built by CERN for the project. SESAME will be the first synchrotron facility—a particle accelerator that produces high-energy x rays for a wide range of uses—to operate in the Middle East. It has gathered support from most of the countries in the area, including Israel and Iran. With $50 million already invested, another $10 million is expected to be needed to complete the project by 2015. SESAME was originally planned as an upgrade of a European synchrotron that was being decommissioned. Because the upgraded version would not produce energies comparable to other synchrotrons, however, the old synchrotron will be used instead as a booster accelerator that then feeds electrons into the main accelerator. Construction began in Allaan, Jordan, in 2004.
Asahi Shimbun: A radiation leak at a Japanese facility went unreported for about 30 hours after scientists there ignored alarms and continued with their work. According to the Japan Atomic Energy Agency (JAEA), the leak occurred on 23 May at the Hadron Experimental Facility at the Japan Proton Accelerator Research Complex. Scientists were bombarding gold with proton beams when the alarm sounded at 11:55am because the beam intensity had spiked to 400 times normal levels. The alarm was turned off and work resumed. Despite multiple stoppages throughout the day as radiation levels continued to surge, the scientists continued with the experiment. At 3:15pm a ventilator was turned on, which leaked radiation outside the facility. Japan’s Nuclear Regulation Authority was not notified of the leak until 9:20pm the next day. The incident fuels accusations of lax safety oversight on the part of the JAEA.
Quantum Diaries: A 15.24-m-diameter electromagnet built and used in the 1990s at Brookhaven National Laboratory in New York is to be moved to Illinois later this year. The ring-shaped electromagnet and other parts of that original experiment will now be used in the Muon g−2 to study the properties of muons. Transporting the large magnet to Fermilab in Batavia, Illinois, will cost almost 10 times less than building a new ring from scratch. The ring will sail on a barge down the East Coast, pass around Florida, and then head up the Mississippi River before being transferred to a specially designed flatbed truck for the final drive to Fermilab. The ring itself is used to trap and store muons, which “wobble” when held in a magnetic field. Although the amount of wobble measured in the older experiment did not match scientists’ predictions, Fermilab’s more intense and pure beam of muons may help attain a more definitive measurement.
New York Times: The Kewaunee power plant in Wisconsin has been closed by Dominion, the private power company based in Richmond, Virginia, that purchased the plant in 2005. That makes it the first nuclear power plant that will have its decommissioning handled by a for-profit company instead of a local, regulated utility. The company has not announced whether it plans to dismantle the plant or wait for the radioactivity to subside and then refit it with modern systems. Either process will take decades and is expected to cost nearly $1 billion. However, the cost of decommissioning is constantly in flux, and predicting costs more than five or six years ahead is difficult. Dominion says it has set aside enough money to cover the process, but it also expects to receive additional funds from the Department of Energy. DOE had agreed to begin removing spent fuel rods from the plant a decade ago but has yet to begin the process. Legal proceedings against the department will likely provide Dominion with $350 million.
Ars Technica: Two neutrino-induced events with energy greater than 1 PeV have been reported by researchers at the IceCube Neutrino Observatory located at the South Pole. The observation is significant because it is likely the neutrinos originated in some high-energy event distant from Earth. Trillions of neutrinos, which emanate from a number of sources such as nuclear reactions in the Sun, pass through Earth every second. But they are extremely difficult to detect because they almost never interact with normal matter. Embedded in Antarctic ice, IceCube’s strings of photodetectors watch for the telltale emission of Cherenkov radiation when a neutrino passing through happens to collide with an atom in the ice. Most of the high-energy neutrinos detected by IceCube have come from cosmic rays colliding with atoms in Earth’s atmosphere. Because of the extremely high energy of the newly detected neutrinos, however, researchers believe they may be the first indication of an astrophysical high-energy neutrino flux—an extremely energetic event that occurs far out in the universe. Longer sampling times and more data will be required to verify that finding.
BBC: One of the detectors at CERN’s Large Hadron Collider is dedicated to studying the decay paths of B mesons—particles made of combinations of quarks. A paper submitted to Physical Review Letters has revealed that the decay path of the Bs meson favors the production of matter over antimatter. Chris Parkes of the University of Manchester in the UK says that one in every four decays exhibits that behavior—known as CP violation. The production of more matter than antimatter is predicted by the standard model, and this is the first evidence that Bs mesons decay as predicted. Other chargeless mesons have also shown that low rate of CP violation. The investigation of the rates of CP violation is part of the effort to understand why there is significantly more matter than antimatter in the universe. If equal amounts of matter and antimatter had been created after the Big Bang, then all the particles would have annihilated each other. However, the rates of CP violation observed so far are not large enough to explain the current proportions of matter and antimatter that exist in the universe today.
New York Times: Two years after the Fukushima nuclear accident in Japan, the Environmental Protection Agency is updating its procedures for dealing with nuclear accidents, some of which have been in place since 1991 and which many experts in the industry say are overly cautious. The new guidelines will address not only initial emergency response but also long-term questions such as when can people return to affected areas. In light of the Japanese experience after Fukushima, the US is proposing raising the threshold for declaring affected land to be contaminated. Although antinuclear groups oppose any loosening of current guidelines, government officials maintain that the proposed revisions are “not in any way relaxing advice about cleanup standards or allowable doses,” according to Jonathan Edwards, director of the EPA’s radiation protection division.
Nature: Between 2003 and 2008 the Cryogenic Dark Matter Search (CDMS) used silicon detectors cooled to 40 mK and located deep in a mine in Minnesota to seek evidence of weakly interacting massive particles (WIMPs), one of the possible forms of dark matter. When a particle collides with the detectors, the interaction is detected as an increase in temperature. Despite the shielding provided by the mine, it is difficult to separate WIMP collisions from background events. Two previous CDMS-detected events have been shown to involve only non-WIMP particles. Now Kevin McCarthy of MIT and his colleagues, who have been analyzing the data collected by the project, have detected three collision events that may be indicative of WIMPs. The three new events occurred when the background should have produced just 0.7 such events. However, the strength of the signal was not strong enough to be considered a true discovery. The interactions, if shown to involve new particles, would give them masses of 8.6 GeV, which is much lower than expected for most theorized WIMPs. The SuperCDMS experiment and other WIMP detectors may provide the evidence necessary to confirm or refute the potential discovery.
BBC: The High-Altitude Water Cherenkov (HAWC) Observatory, being built near Puebla, Mexico, is already detecting cosmic- and gamma-ray particles in Earth’s atmosphere. HAWC will consist of 300 tanks of pure water with detectors at the bottom. As the high-energy particles enter the atmosphere, they strike molecules in the air, setting off a chain-reaction particle cascade called an extensive air shower. When those faster-than-light particles enter HAWC’s water tanks, they emit the electromagnetic equivalent of a sonic boom. It is those flashes of light that can be used to determine the type, energy, and direction of the primary cosmic- and gamma-ray particles. With just 30 tanks up and running, HAWC is already producing images, according to HAWC collaboration member Thomas Weisgarber of the University of Wisconsin–Madison during his presentation Saturday at the April meeting of the American Physical Society in Denver. The full array should be in place by 2014.
Physics: The first results from the Alpha Magnetic Spectrometer (AMS) experiment, a project 18 years in the making and orbiting aboard the International Space Station since May 2011, were announced yesterday. AMS counts the arrival of positrons, the electron’s antiparticle, as a function of their energy. Years ago the PAMELA and Fermi missions established that high-energy positrons were more copious than well-understood cosmic-ray theory predicted; AMS confirmed those results with much greater precision and extended the measured positron energy range. An exciting possibility is that the extra positrons result from interactions of the mysterious dark matter that makes 5/6 of the universe’s material stuff, but astrophysical objects such as pulsars also generate positrons. AMS has been collecting data for two years and should be collecting for another decade or two. The instrument will further extend the energy range of the positron spectrum and may provide the data that convincingly determine the source of the positron excess.