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In the most stringent test yet of differences between protons and antiprotons, scientists investigated the ratio of electric charge to mass in about 6,500 pairs of these particles over a 35-day period. To keep antimatter and matter from coming into contact, the researchers trapped protons and antiprotons in magnetic fields. Then they measured how these particles moved in a cyclical manner in those fields, a characteristic known as their cyclotron frequency, which is proportional to both the charge-to-mass ratio of those particles and the strength of the magnetic field.
(Technically, the researchers did not use simple protons in the experiments, but negative hydrogen ions, which each consist of a proton surrounded by two electrons. This was done to simplify the experiments — antiprotons and negative hydrogen ions are both negatively charged, and so respond the same way to magnetic fields. The scientists could easily account for the effects these electrons had during the experiments.
The scientists found the charge-to-mass ratio of protons and antiprotons "is identical to within just 69 parts per trillion," Ulmer said in a statement. This measurement is four times better than previous measurements of this ratio.
In addition, the researchers also discovered that the charge-to-mass ratios they measured do not vary by more than 720 parts per trillion per day, as Earth rotates on its axis and travels around the sun. This suggests that protons and antiprotons behave the same way over time as they zip through space at the same velocity, meaning they do not violate what is known as charge-parity-time, or CPT symmetry.
[...]
Using more stable magnetic fields and other approaches, the scientists plan to achieve measurements that are at least 10 times more precise than what they found so far, Ulmer said.
If matter and anti-matter are mirrors of each other, and were created in equal measure by the Big Bang, then where did all the anti-matter go?
See our related story: Time-Symmetric Formulation of Quantum Theory Provides New Understanding of Causality.
(Score: 2, Insightful) by khallow on Friday August 14 2015, @03:07PM
Well, they say they can:
Point is that they aren't measuring anti-protons no matter what they are saying. And when you're trying to measure very subtle phenomena to parts per trillion (or less), that distinction matters.
I would guess here that that they're really proving the concept right now and then planning to hook the apparatus up to a source of anti-protons, say at one of the major particle accelerators.
(Score: 0) by Anonymous Coward on Friday August 14 2015, @03:41PM
And as a professional physicist, I would call them on that claim. Otherwise all they've done is noted that there is no difference between protons traveling different directions around a cyclotron, to at least 69 parts per trillion. There is probably interesting things to infer from that, but it doesn't say a lot about antiprotons.
I suspect that is the case too, or I hope that is the case. Otherwise, their current result is not as interesting as the article suggests.
(Score: 2) by mcgrew on Friday August 14 2015, @07:33PM
They already did; scroll down, I provided a link.
mcgrewbooks.com mcgrew.info nooze.org
(Score: 1) by khallow on Friday August 14 2015, @09:58PM
(Score: 2) by mcgrew on Sunday August 16 2015, @10:39PM
The neutrino experiment was the one.
mcgrewbooks.com mcgrew.info nooze.org