Recently, the Large Hadron Collider has been ignited. Researchers at the European Nuclear Research Center have used it to accelerate the 'lead atom' with a single electron. This is the first time this large device has been used to accelerate such 'lead atoms'.
As the world's largest particle accelerator, since its inception in 2009, the daily work of the Large Hadron Collider has been to accelerate proton and completely stripped lead nuclei.
The electronics are very small and very difficult
Since the particle accelerator works by accelerating the charged particles in the electric field and increasing the energy, the uncharged neutral particles cannot be accelerated. To accelerate the particles, they must be turned into charged particles, so that it Can be accelerated by interaction with forces in the accelerator electric field.
As we all know, an atom consists of a nucleus and an electron moving around a nucleus. The nucleus is composed of protons and neutrons. Each proton carries a unit of positive charge, neutrons are not positive, and each electron carries a unit of negative The charge, the number of positive and negative charges of a complete atom is equal, in an equilibrium state, as long as an electron is stripped, the 'atoms' will lose balance and become positively charged ions.
In this experiment, the researchers first stripped 82 electrons of lead atoms into the electron ring resonance device, leaving the lead atoms into positively charged ions and then accelerating them.
Previously, the Large Hadron Collider never accelerated the electron-bearing nucleus. At the European Nuclear Research Center, the large-scale international cooperation group of the ultra-high-energy heavy ion collision experiment, the Chinese project coordinator, Zhou Zhongcui, a professor at Huazhong Normal University, said that the acceleration has a The 'lead atom' of electrons is quite difficult. 'When moving in the accelerator ring, if the vacuum inside the ring is not high, it is possible to knock this electron off, and thus change the charge state of the accelerated 'atoms'. The experiment failed; on the other hand, the 'atoms' that are being accelerated may also collide with other atoms, which will cause strong damage to the annular pipe wall, which will be a big accident. ' Zhou Daicui said.
At the same time, the Large Hadron Collider engineer Michela Sauman also held a similar view. He said that accelerating the electron-bearing nucleus is very challenging because it is easy to accidentally strip the electrons. When it occurs, the nucleus will hit the wall where the ion beam is located.
In addition, Zhou Daicui pointed out that in addition to the extremely high requirements of the acceleration ring vacuum, the charge-to-mass ratio of the accelerated 'atoms' is also directly related to the difficulty of its acceleration. The so-called charge-to-mass ratio refers to the ratio of the charge of the nucleus to the atomic mass. 'When the charge-to-mass ratio of the accelerated particles is 1, that is, when the charge amount is the same as the mass, the acceleration is relatively easy; the smaller the charge-to-mass ratio, the more difficult the acceleration. The charge-to-mass ratio of the lead nucleus is about 0.39, and its acceleration difficulty It is very big. ' Zhou Daicui said.
Old method new level
The press release issued by the European Nuclear Research Center said that the test was to test the feasibility of the 'gamma ray factory' scenario, and it is possible to generate high-intensity gamma rays in the future with the Large Hadron Collider.
The so-called gamma ray is a kind of high-energy electromagnetic wave with extremely short wavelength. It has been widely used in basic science and applied science. Since the 1970s, the United States, Britain, France, Japan and Russia have used laser photon impact ring motion. Electronic means to generate gamma rays, the highest energy of which can reach several GeVs ( billion electron volts).
'The current experiment on the Large Hadron Collider is to use an existing accelerator device to accelerate an electron nucleus as a carrier, first accelerate it, and then use laser photons to bombard the high-speed rotating 'atoms' to make it jump. To the excited state. When the electron transitions from the high-excited state to the low-excited state, a photon is released, which is the gamma ray. But since the 'atoms' have been accelerated to the TeV (Tillion volts) level to approach the speed of light The speed of motion, the energy and intensity of the emitted photons will be greatly improved. Compared with the traditional gamma ray source method of laser photon impacting the circular acceleration, the gamma ray intensity under this new concept will be the traditional gamma ray source. Tens of times more strength. ' Zhou Daicui said.
Zhou Daicui said that compared with the gamma ray generated by the traditional method, the gamma ray produced by this experiment is very different in terms of energy, intensity, and use. This gamma ray can be applied directly and has sufficient energy. To produce the usual 'substance' particles, such as quarks, electrons, etc. These high-energy gamma rays can become massive particles, and can even become new substances, such as dark matter. They can also be sources of new particle beams, such as Muon beam, even polarized positive and negative electrons, polarized muon, neutrino, neutron, vector meson, radioactive ion, etc. It has broad application prospects in basic physics frontier research, modern technology and application fields. Even some scientists say it 'may open up new research opportunities in the unknown basic physics and industrial applications'.
