Fuente: CERN Document Server: News Articles
Expuesto el: domingo, 01 de abril de 2012 2:05
Autor: CERN Document Server: News Articles
Asunto: CERN scientists report sidereal influence on the behaviour of antimatter
| CERN scientists today reported an unexpected effect in the behaviour of antiprotons in the ALPHA experiment's particle trap. ALPHA traps antiprotons from the laboratory's Antiproton Decelerator and mixes them with positrons to form antihydrogen. The experiment's ultimate goal is to perform spectroscopic measurements on antihydrogen atoms in order to investigate nature's preference for matter over antimatter. ALPHA reported an important step forward last month with the announcement that they had succeeded in changing the internal state of antihydrogen atoms using microwaves. One of the key stages in CERN's antimatter programme is slowing the antiprotons down as much as possible, a process known as cooling. In all measurements to date, the ALPHA experiment has cooled the antiprotons to a temperature of just 0.5 Kelvin. However, when the experiment ran on Monday 26 March, they observed antiprotons cooled to 0.4 Kelvin: in other words, they were moving more slowly than usual. Another curious phenomenon was that the temperatures of the antiprotons followed a Poisson distribution instead of the usual Gaussian. The following day, the antiprotons were back to their normal temperature of 0.5 Kelvin. "We took a long time to figure this one out," explained collaboration spokesperson, Jeffrey Hangst. "On Monday, the antiprotons were particularly cold, but they responded well to microwave warming, allowing us to conclude the run. On Tuesday, our antiprotons were back to normal." The solution came from an unexpected direction. "There was something else strange about Monday's run," said Hangst. "Our run coordinator Niels Madsen arrived an hour late, which is very uncharacteristic behaviour for him." This provided the clue the ALPHA collaboration needed. "I'd forgotten that the time changed over the weekend," said Madsen. "And of course no one had told the antiprotons that the clocks went forward either, so they were just a little more slow than usual. By the time we got to Tuesday, they'd adjusted to Central European Summer Time." |
