Researchers from U.S. Department of Energy's Thomas Jefferson National Accelerator Facility, Argonne National Laboratory, have discovered the mysterious location of the mass of proton, a breakthrough discovery in the study of the sub-atomic particle
Protons are the positively charged particles of an atom. Atoms are the fundamental makeup of every matter. Beside protons, other particles known to be present in an atom are electrons and neutrons.
A lot is known about proton but the true nature of its mass has remained a mystery since its discovery in in 1917 by Rutherford. According to the atomic cloud model of an atom, proton and neutron locate at the center of an atom to form the nucleon or the nucleus, which contains the mass of an atom, while the negatively charged electrons spin around the nucleus.
Physicists have tried for years to determine what causes protons to be more massive than their makeups. But this new discovery seems to be the end of that puzzle. The researchers have finally pinpointed the source of this extra mass using electron beams, liquid hydrogen, and even more complex computer models. The team was able to determine that the extra mass of the proton hides at its centre.
The research team discovered that the mass of a proton is truly larger than the sum of its parts, and that this extra mass hides in the center of the proton building block quarks.
The experiment was carried out by shooting a powerful beam of 10.6 GeV (billion electron-volt) electrons from the Continuous Electron Beam Accelerator Facility (CEBAF) at a block of copper to emit bremsstrahlung radiation as photons helping the researchers to measure the mass radius of the proton, which is much smaller than its charge radius.
The experiment which is known as J/psi particle production is often employed to help researchers measure the strong-force gluon radius of a proton, thereby revealing the mass radius that the extra mass was hiding in.
The team also discovered that the detected proton extra mass is created by the strong forces between the three valence quarks that make up the sub-atomic particle and the interactions between the quarks and the gluons that hold them together. It was also discovered that the mass is produced by the movement of the quarks within the proton.
Proton Quark Structure
There are two up quarks and one down quark. Each one has blue, red and green color charge, which "add up" to make the proton "colorless". The yellow springs symbolize gluon flux tubes, which hold the quarks together due to the strong force. The mass is discovered to locate at the center of this gluon flux.
Credit: Wikimedia Commons
The team's findings, published this week, have shed light on the mystery of how protons gain mass, and could help further our understanding of particle physics and the quantum world.
Announcing the new development, Zein-Eddine Meziani, staff scientist at DOE's Argonne National Laboratory and experiment co-spokesperson, said that the team was excited over this massive discovery that will change the way many see proton.
"The bottom line for me—there's an excitement right now. Could we find a way to confirm what we are seeing? Is this new picture information going to stick? But to me, this is really very exciting. Because if I think now of a proton, we have more information about it now than we've ever had before," Meziani said.
These breakthrough findings could have far-reaching implications for the future of particle physics. The researchers plan to continue their works, exploring the physics of J/psi particles and further probing the mysterious mass of proton to inform the public about their discovery as a confirmatory experiment to the previous ones.
Protons are the positively charged particles of an atom. Atoms are the fundamental makeup of every matter. Beside protons, other particles known to be present in an atom are electrons and neutrons.
A lot is known about proton but the true nature of its mass has remained a mystery since its discovery in in 1917 by Rutherford. According to the atomic cloud model of an atom, proton and neutron locate at the center of an atom to form the nucleon or the nucleus, which contains the mass of an atom, while the negatively charged electrons spin around the nucleus.
Physicists have tried for years to determine what causes protons to be more massive than their makeups. But this new discovery seems to be the end of that puzzle. The researchers have finally pinpointed the source of this extra mass using electron beams, liquid hydrogen, and even more complex computer models. The team was able to determine that the extra mass of the proton hides at its centre.
The research team discovered that the mass of a proton is truly larger than the sum of its parts, and that this extra mass hides in the center of the proton building block quarks.
The experiment was carried out by shooting a powerful beam of 10.6 GeV (billion electron-volt) electrons from the Continuous Electron Beam Accelerator Facility (CEBAF) at a block of copper to emit bremsstrahlung radiation as photons helping the researchers to measure the mass radius of the proton, which is much smaller than its charge radius.
The experiment which is known as J/psi particle production is often employed to help researchers measure the strong-force gluon radius of a proton, thereby revealing the mass radius that the extra mass was hiding in.
The team also discovered that the detected proton extra mass is created by the strong forces between the three valence quarks that make up the sub-atomic particle and the interactions between the quarks and the gluons that hold them together. It was also discovered that the mass is produced by the movement of the quarks within the proton.
Proton Quark Structure
There are two up quarks and one down quark. Each one has blue, red and green color charge, which "add up" to make the proton "colorless". The yellow springs symbolize gluon flux tubes, which hold the quarks together due to the strong force. The mass is discovered to locate at the center of this gluon flux.
Credit: Wikimedia CommonsThe radius of this mass structure is smaller than the charge radius, and so it kind of gives us a sense of the hierarchy of the mass versus the charge structure of the nucleon," said experiment co-spokesperson Mark Jones, Jefferson Lab's Halls A&C leader.
Announcing the new development, Zein-Eddine Meziani, staff scientist at DOE's Argonne National Laboratory and experiment co-spokesperson, said that the team was excited over this massive discovery that will change the way many see proton.
"The bottom line for me—there's an excitement right now. Could we find a way to confirm what we are seeing? Is this new picture information going to stick? But to me, this is really very exciting. Because if I think now of a proton, we have more information about it now than we've ever had before," Meziani said.
These breakthrough findings could have far-reaching implications for the future of particle physics. The researchers plan to continue their works, exploring the physics of J/psi particles and further probing the mysterious mass of proton to inform the public about their discovery as a confirmatory experiment to the previous ones.
