A helion (symbol h) is the nucleus of a helium atom, a doubly positively charged cation. The term helion is a portmanteau of helium and ion, and in practice refers specifically to the nucleus of the helium-3 isotope, consisting of two protons and one neutron. The nucleus of the other stable isotope of helium, helium-4, which consists of two protons and two neutrons, is called an alpha particle.

This particle is the daughter product in the beta-minus decay of tritium, an isotope of hydrogen:

3
1H
→ 3
2He1+
 		+ 
e−
 		+ 
ν
e

CODATA reports the mass of a helion particle as mh = 5.0064127796(15)×10−27 kg[1] = 3.014932247175(97) Da.[2]

Helions are intermediate products in the proton–proton chain reaction in stellar fusion.

An antihelion is the antiparticle of a helion, consisting of two antiprotons and an antineutron.

References

  1. ↑ "2018 CODATA Value: helion mass". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. Retrieved 2022-09-11.
  2. ↑ "2018 CODATA Value: helion mass in u". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. Retrieved 2022-09-11.


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