CERN collider could be world's fastest stopwatch

Posted by Flora Malein

The CERN supercollider could become the world’s most precise stopwatch, thanks to a new method of keeping time devised by researchers at Vienna University of Technology (TU), Austria.

The clock would keep time based on extremely short light pulses given out when ‘heavy ions’, nuclei that belong to heavy atoms such as lead, are smashed together at speed within the collider.
 
These light pulses are not currently measurable, but new equipment due to be installed at CERN in 2018 would enable scientists to measure time on the shortest possible timescales to date. The report is published in the Physical Review Letters of the American Physical Society.
 
When measuring very short timescales, scientists currently use ultra-short laser pulses. Today, pulse durations of the order of ‘attoseconds’ - measurements in the order of billionths of a billionths of a second, 10-18 seconds - can be detected. But these records are set to be broken by the new clock.
 
‘Atomic nuclei in particle colliders like the LHC (Large Hadron Collider) at CERN or at RHIC (Relativistic Heavy Ion Collider) can create light pulses which are still a million times shorter than that’, says Dr Andreas Ipp, of the Institute for Theoretical Physics at TU Vienna.
 
The proposed stop clock would be able to measure time in ‘yoctoseconds’, one septillionth of a second or 10-24 seconds. To put this in perspective, yoctoseconds are the next meaningful order of magnitude up from the time required for light to travel one Planck length, the briefest physcial span of time: 10-44 seconds. So the new stop clock would be very quick indeed.
 
When the atomic nuclei collide, a sub-atomic soup known as ‘quark-gluon plasma’ is created between the atoms. It is from this plasma that the very short light pulses are given out. Conventional measurement techniques are currently too slow to resolve the flashes of light which are on the yoctosecond timescale.
 
The new method has so far only been tested in computer simulations but should be put into practice after the new piece of equipment, the ‘forward calorimeter,’ is installed at CERN in 2018.