In experiments at the Paul Scherrer Institute PSI, an international research collaboration with ETH Zurich involvement has measured the radius of the atomic nucleus of helium five times more precisely than ever before. With the aid of the new value, fundamental physical theories can be tested.
After hydrogen, helium is the second most abundant element in the universe. Around one-fourth of the atomic nuclei that formed in the first few minutes after the Big Bang were helium nuclei. These consist of four building blocks: two protons and two neutrons. For fundamental physics, it is crucial to know the properties of the helium nucleus, among other things to understand the processes in other atomic nuclei that are heavier than helium. “The helium nucleus is a very fundamental nucleus”, says Aldo Antognini, a physicist at PSI and ETH Zurich.
With this, the international research collaboration succeeded in determining the size of the helium nucleus around five times more precisely than was possible in previous measurements. The group is publishing its results today in the renowned scientific journal “Nature”. According to their findings, the so-called mean charge radius of the helium nucleus is 1.67824 femtometers (there are 1 quadrillion femtometers in 1 meter).
Source: “Size of helium nucleus measured more precisely than ever before”, Barbara Vonarburg, Zurich ETH News