Abstract
A search for possible existence of anomalously heavy isotopes of helium in the Earth's atmosphere was discussed. The helium sample was extracted from air with sorption pumps cooled to 80K by liquid nitrogen. Sensitive laser spectroscopy technique was used to search for a charged particle accompanied by two electrons as an anomalously heavy isotope of helium in the Earth's atmosphere. It was observed that in helium, the isotope shift is dominated by the mass shift that results from the change of the nuclear mass.