The super weapon of element synthesis! See what is the key to artificially synthesizing elements →

Welcome to Science Popularization China’s special winter vacation column “ High-tech Classes for Children ”!

The series of scientific documentaries "Opening the Door to the Universe", produced by the Science and Technology Communication Center of the China Association for Science and Technology and co-produced and broadcast by the Film and Television Documentary Center of China Central Radio and Television and other units, was recently released on CCTV-9.

This film focuses on a series of large scientific facilities independently developed by my country, provides a scientific interpretation of my country's major scientific and technological infrastructure, and showcases the achievements made in the construction of my country's major scientific and technological infrastructure and the important scientific research results produced by these super equipment.

Let’s take a look at some of the major scientific facilities!

Do you know how the universe is made up? Where do the elements that make up our bodies come from? How to synthesize element 119?

Do you believe it? Some of the elements that make up our bodies come from the Big Bang about 13.8 billion years ago, which instantly produced a large amount of hydrogen, helium and a small amount of lithium. Later, with the emergence of stars, hydrogen and helium produced all the elements before iron through nuclear fusion inside the stars. In the following tens of billions of years, other elements after iron were formed through the burning of medium and low mass star cores, supernova explosions and neutron star mergers. All these elements make up our colorful universe.

However, many elements may exist in the universe, but may not be found on Earth. In fact, the elements after uranium 92 on the periodic table that we are familiar with were all artificially synthesized by scientists.

In Lanzhou, an important city in northwest China, lies a technological giant - the Lanzhou Heavy Ion Accelerator, which is a super weapon for element synthesis .

The key to artificially synthesizing elements is to use the nucleus of one element as a "cannonball" to bombard the nucleus of another element. When the two nuclei fuse, a new element is produced. The number of protons in the new element is the sum of the number of protons in the previous two elements. For example, using a boron nucleus with an atomic number of 5 to bombard a californium nucleus with an atomic number of 98 will produce element 103, lawrencium.

There are currently 118 elements discovered or synthesized by humans. The next goal of scientists is to synthesize element 119.

Zhang Zhiyuan, a researcher at the Institute of Modern Physics of the Chinese Academy of Sciences, said that element 118 was synthesized by bombarding element 98, californium, with calcium 48 as a "cannonball". To make element 119, all you have to do is replace californium with its next element, which is element 99.

However, the world's production of element 99, einsteinium, is only in the microgram level and cannot be made into target material. One solution is to change the combination of the shell nucleus and the target nucleus.

Changing the combination of the projectile nucleus and the target nucleus will lead to the following problems: the repulsive force between the two heavy nuclei will be greatly strengthened, and the possibility of the two nuclei fusing will be greatly reduced. Therefore, only by bombarding the heavy target nucleus with the lightest projectile nucleus possible can the synthesis of element 119 be possible.

In order to increase the probability of synthesizing new elements, it is necessary to further increase the number of cannonball particle beams per unit time, that is, the beam intensity. To this end, researchers built an accelerator dedicated to superheavy element research, which provides good experimental conditions for the impact synthesis of new elements.

"We accelerate the beam particles to nearly one-tenth the speed of light and let it bombard another atomic nucleus," Zhang Zhiyuan said.

The ion source of the heavy ion accelerator is the starting point of the entire device, and the accelerated cannonball atomic nuclei enter the accelerator tunnel.

These metal targets are only a few microns thick. The beam formed by the atomic nuclei of the shells hits the metal material, causing a nuclear reaction and fusing them into new atomic nuclei.

When the newly synthesized atomic nucleus enters the detection system, it will undergo a series of decays and will eventually be detected by the detector.

Once successfully identified, it means that the superheavy element has been successfully synthesized.

At present, this superheavy element research accelerator has been running stably for more than 10,000 hours. Although it is difficult to synthesize element 119, its research has seen the light of day.

Planning and production

Source: Voice of China Association for Science and Technology

Editor: Fu Sijia

Proofread by Xu Lai and Lin Lin