Who was the neutron discovered by?

"The modern atomic model would not be possible without the proton!"


In 1919, the discovery of the proton revolutionized science. A year of 100 knowledge interview with the astrophysicist Professor Dr. Karl-Heinz Kampert

What exactly is a proton?

Kampert: The word proton contains the prefix proto from ancient Greek, which means something like the first. And the proton is actually the first particle from which atomic nuclei are built. The proton is a prototype of an atomic nucleus.

Who discovered the proton?

Kampert: The discovery goes back to the New Zealand physicist Ernest Rutherford, who was working in England at the time. Most of them know Rutherford from school lessons, namely from Rutherford's atomic model. This means that the mass of an atom is concentrated in a tiny little nucleus around which the electrons then move. This is what we have of the atom, although the electrons are not actually orbiting the nucleus. Rutherford had already received a Nobel Prize in Chemistry in 1908, before the discovery of the proton, because he had studied radioactivity more closely, which had been discovered in 1896. And he found, we also know that from school lessons, that with radioactivity there are three different types of radiation: alpha, beta and gamma radiation. And for that he got the Nobel Prize. He then continued to work on the structure of the atomic nucleus and came across the protons.

How did he discover the proton? Was that a coincidence or did he search specifically?

Kampert: A few years ago, the long-term, targeted search for the Higgs particle was successfully completed. In the case of the proton, the situation was different and a specific search for the proton did not take place in this form. However, it was not a chance discovery either, but rather a targeted investigation of the structure of atomic nuclei. The key that led to the fact that a proton must exist as such was that Rutherford had managed to convert nuclei into one another in a targeted manner. In concrete terms, he succeeded in converting nitrogen nuclei into oxygen nuclei simply by adding a proton to the nitrogen nucleus. So he added a unit to the core to create another core.

Why was the discovery of the proton so important to science?

Kampert: Modern science would actually not be possible without a modern atomic model. And the proton is the most important part of this atomic model. All modern science is based on it and with the discovery of the proton an incomparable simplification took place. In nature we know over 3000 different types of atoms, atomic nuclei. And these were ultimately traced back to just three individual building blocks, namely the proton, the neutral sister particle, the neutron, and the electrons that circle around it. We attribute all of the matter that surrounds us to these three building blocks. That was the starting point. And I think Rutherford could easily have received the Nobel Prize in Physics again for this fundamental discovery.

Where are protons used today?

Kampert: Actually in everything we pick up, because all matter consists primarily of protons and neutrons. Here are two examples from diagnosis and therapy in medicine, in which protons are used in a targeted manner. First the diagnosis. We all know the magnetic resonance tomograph, today we mostly refer to it as MRT (magnetic resonance tomography). So when we take an MRI image of a part of our body, we are specifically using the protons in our body. They are deflected in the magnetic field and then, so to speak, made to flip over. This is then registered three-dimensionally and we can achieve a high-resolution three-dimensional image of a body. This happens specifically with the protons in the body. In therapy we use protons in radiation. If we have a tumor that is difficult to access, be it in the inner area of ​​the brain or behind the eyeball, where it is not so easy to operate, proton therapy has been around for three decades now. Patients are brought to the particle accelerator, where they are specifically irradiated with protons. This can be set so that the cancer cells are also killed selectively within the body. So not the cells in front of it, but specifically in the cancer area behind.
Very topical: Researchers have discovered a new form of matter!
So far, only 17 percent of the mass of space can be assigned to the researched so-called baryonic matter. Conversely, this means: 83 percent of the mass consists of dark matter about which almost nothing is known so far. Researchers have been trying to find all existing particles for some time now. Scientists in Japan have now made a small breakthrough: With the help of a particle accelerator, they have created a new form of matter. A seldom occurring particle called anti-kaon was used for this.

Does this discovery help you in space exploration?

Kampert: A completely new kind of matter really was created there. Atomic nuclei are usually composed of protons and neutrons. And in that case they managed to put this kaon in. The nucleus that was left at the end consisted of two protons and a negatively charged kaon, i.e. an anti-kaon. The entire object then basically has almost the properties of a hydrogen atom nucleus again, but with a completely different matter in the center, which we call strange matter, because the kaons belong to the group of strange particles. Strange because when they were discovered in cosmic rays they exhibited strange properties in terms of their production and decay. Now these strange particles have been built into an atomic nucleus for the first time and this new matter has been created. The core, however, is not stable but disintegrates after a short time. But it just forms temporarily. And the possibility that this opens up for physics, even if the atomic nucleus lives only for a short time, means to be able to examine and better study the forces between the particles that hold the atomic nuclei together as a whole. So we also learn something about normal matter with it. Whether this type of matter also exists in nature is then another question. It is certainly not around us here. However, it is quite possible that this type of matter - has been speculated about for a long time - could appear inside neutron stars in the universe. Neutron stars are atomic nuclei with an extension of 10 kilometers. This is really pure atomic nuclear matter and inside these neutron stars there are enormously high pressures. At these high pressures one now suspects that exotic matter can arise. I don't think this matter will appear as dark matter because it only lives for a short time. Dark matter in the universe has to live a long time because it is constantly present everywhere in order to be able to maintain the missing gravity. For dark matter we actually need stable particles, stable in relation to the lifespan of the universe. In my opinion, you will not really solve the question of dark matter with these new findings, but they will enable us to better understand the forces in atomic nuclei and also the interior of neutron stars in astrophysics.

Uwe Blass (interview on March 18, 2019)

Prof. Dr. Karl-Heinz Kampert studied physics from 1977 to 1983 at the Westphalian Wilhelms University in Münster. From 1983 to 1986 Kampert was a research assistant at the Westphalian Wilhelms University and received his doctorate in 1986. He then worked for three years as a postdoctoral research fellow at the large research institution CERN in Switzerland. From 1989 to 1995 he was assistant professor of physics at the University of Münster, during which he completed his habilitation in 1993. He then taught as professor of physics at the University of Karlsruhe and the Karlsruhe Research Center, which both merged in 2009 to form the Karlsruhe Institute of Technology. Since 2003 he has been teaching experimental physics at the Bergische Universität Wuppertal.