0000000000515271
AUTHOR
Rachel Chechik
Search for supermassive nuclei in nature
We report on a search for supermassive nuclei in nature with masses up to 107 amu. Such exotic nuclei might consist, for example, of stable strange matter, which comprises a mixture of up, down, and strange quarks, or of relic particles from the early Universe. The experiments are based on Rutherford backscattering of heavy ions, preferably238U, from various target samples. The measured parameters of a detected particle are its time-of-flight, scattering angle, and specific ionization. From this information the mass of the target nucleus can be inferred. Upper limits for the abundance of strange supermassive nuclei with massesA−4·102 to 107 amu relative to the number of nucleons were found …
A heavy-ion identification system for the detection of rare events
Abstract A large area detection system is described which consists of twelve low-pressure multi-wire proportional counters and is used in the search for exotic super-massive nuclei. The experiments are based on Rutherford backscattering of heavy ions, preferably 208Pb or 238U, from various target samples. The measured parameters of a detected particle are its time-of-flight, scattering angle, and specific ionization. From this information the mass of the target nucleus can be inferred. The present experimental sensitivity for the detection of exotic nuclei with at least twice the mass of the projectile is about 10−12 relative to the number of nucleons.
Search for strange matter by Rutherford backscattering
According to a number of suggestions, stable strange matter could exist in the form of supermassive nuclei (or 'strange nuggets')1,2. In contrast to ordinary nuclei, which contain only 'up' and 'down' quarks, a piece of strange matter should comprise a mixture of 'up', 'down' and 'strange' quarks in roughly equal proportions. Small amounts of strange matter could have survived from the early stages of the Universe1. Alternatively, strange matter might reach the Earth as a flux of strange nuggets produced in collisions of neutron stars3. Limits to the cosmic flux of strange nuggets with masses in the range from 10−4 to 250 g have been obtained in a search for light produced by the nuggets in…