atomic scale: protons are smaller than thought - most accurate laser measure

by:UMeasure     2019-10-15
atomic scale: protons are smaller than thought  -  most accurate laser measure
How many protons can the head of a needle dance?
The answer is far less simple than people think.
It may provide the best new insight
Test of physics theory.
Recently, an international team of scientists tried to find out the actual size of the proton, which is one of the components (
And neutron and Electron)
The atoms that make up our bodies and the world around us.
This week, in the journal Science, researchers found that the radius of the particle was 0.
84087 femtometers.
The millimeter is one in ten billion of 1 m, or the wavelength of the gamma ray is 100 times.
The new measurement is about 4 percentage points smaller than the radius 0 currently accepted.
8768 femtometers, and the small difference presents a mystery.
If the smaller size is correct, there is something missing from the physicist's understanding of quantum electrodynamics, which controls the interaction between light and matter. Proton error?
Physicists at the Swiss Federal Institute of Technology and first author of the paper, Aldo andogini, told Life Science that the difference could mean one of the three things. [pullquote]
First of all, there are some errors in the early work, although it is unlikely considering how many times the various experiments have been repeated.
The second possibility is that some calculations of proton size are lost.
"Maybe we don't fully understand the proton structure," Antognini said . ".
The third explanation is that the current theory of quantum electrodynamics is wrong, although the possibility seems small considering that the theory works well and has been tested many times. [
Weird physics: the coolest little particle in Nature]
This result is not the first time there is a difference.
In 2010, Antognini worked with the international team led by Randolf Pohl of the Garching Max Planck Quantum Optics Institute in Germany to find that the proton radius appeared to be 0.
84185 femtometers.
Scientists have used three methods to measure the size of protons.
One is electron scattering: emitting electrons with negative electricity on the hydrogen nucleus with positive electricity (protons)
And measure how they deflected.
The scattering pattern can then give an idea of how big the charge area is.
The second method is to measure the energy required for electrons to move to different orbital regions around the nucleus.
Electrons usually stay at a certain distance from the nucleus.
Increase their energy and they get excited and move to a different area called orbit.
Then the electrons go back to their non-excited state and emit a photon.
By carefully observing how much energy it takes to move electrons from one orbit to a higher orbit
Energy one, the wavelength of photon emission when the electrons fall back to lower
An energy orbit is possible to estimate the size of a proton.
Finally, the method used in the latest set of experiments involves muonic hydrogen, which is a proton that has muon around it, not electrons.
Like an electron, the muon carries a negative charge, but weighs 207 times.
This means that they are closer to the protons, and it takes more energy to move them to a higher position. Energy orbit.
The greater the energy difference, the easier it will be to measure.
Emit a laser on muonic hydrogen to stimulate muon and move it to a different orbit.
Muon then fell back to a lower level
Energy state of emission X-ray photon.
The first two methods have been used for decades to derive a larger value for the proton radius.
Scientists say the latter approach has less uncertainty but has found less uncertainty.
These calculations, however, are rather complex.
Not only did the new proton measurement team, which conducted the experiment at the Paul Scherrer Institute in Switzerland, conduct the muonic hydrogen experiment for the second time, but they also took steps to ensure more accurate measurements.
Differences still exist.
"Maybe there's something in [proton]
"The structure is only highlighted by muons," andogney said . ". [
Strange: Ten Unexplained Phenomena
That's why the new value is proving so mysterious.
Quantum electrodynamics (QED)
Experts say this may be right, and early experiments are unlikely to go wrong due to simple errors.
Helen Margolis, a research scientist at the National Physics Laboratory in the United States, said: "There may be some terminology missing in computing . "K.
He was not involved in the study.
"So far, QED has been tested to an incredible level, but the math base is not as safe as you think.
Chad Ozel, associate professor of physics and astronomy at the Union College and author of How to teach your dog physics (Scribner, 2010)
He said that because of the questions they raised, the results were generally good for physics.
"It's really boring when all the measurements and theories are consistent.
This disagreement is not the Higgs particle that we can talk about.
"Copyright 2013 Life Science, a technology media network company.
All rights reserved.
This material may not be published, broadcast, rewritten or re-distributed.
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