Search

SQM-ISS is a detector that will search from the International Space Station for massive particles possibly present among the cosmic rays. Among them, we mention strange quark matter, Q-Balls, lumps of fermionic exotic compact stars, Primordial Black Holes, mirror matter, Fermi balls, etc. These compact, dense objects would be much heavier than normal nuclei, have velocities of galaxy-bound systems, and would be deeply penetrating. The detector is based on a stack of scintillator and piezoelectric elements which can provide information on both the charge state and mass, with the additional timing information allowing to determine the speed of the particle, searching for particles with velocities of the order of galactic rotation speed (v ≲ 250 km/s). In this work, we describe the apparatus and its observational capabilities.

Many theories predict the existence of very heavy compact objects, that in terms of sizes would belong to the realms of nuclear or atomic physics, but in terms of masses could extend to the macroscopic world, reaching kilograms, tonnes, or more. If they exist, it is likely that they reach our planet with high speeds and cross the atmosphere. Because of their high mass-to-size ratio and huge energy, in many cases, they would leave behind a trail in the form of sound and seismic waves, etches, or light in transparent media. Here we show results of a search for such objects in visual photographs of the sky taken by the "Pi of the Sky" experiment, illustrated with the most stringent limits on the isotropic flux of incoming so-called nuclearites, spanning between 5.4×10^{-20} and 2.2×10^{-21}  cm^{-2} s^{-1} sr^{-1} for masses between 100 g and 100 kg. In addition we establish a directional flux limit under an assumption of a static "sea" of nuclearites in the Galaxy, which spans between 1.5×10^{-18} and 2.1×10^{-19}  cm^{-2} s^{-1} in the same mass range. The general nature of the limits presented should allow one to constrain many specific models predicting the existence of heavy compact objects and both particle physics and astrophysical processes leading to their creation, and their sources.