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Search for low-Z nuclei containing massive stable particles.

Several recent theories suggest the existence of massive stable particles that might exist in nature as remnants of the big bang. Such particles could be hidden in ordinary terrestrial matter as anomalous-mass isotopes of ordinary nuclei. A search for massive isotopes of hydrogen, lithium, beryllium, boron, carbon, oxygen, and fluorine was performed using an electrostatic charged-particle spectrometer in conjunction with a tandem accelerator. A variety of materials was sampled, including some that had heavy-particle concentrations enriched by various means. No evidence for stable isotopes with masses between 100 and 10 000 amu was found. The sensitivity of the search was greater by several orders of magnitude than the expected concentration levels, limiting the types of stable particles that could exist in this mass range.