If an astronomical strangelet were to hit the atmosphere, it would result in a shower of high energy particles. Several experiments originally conceived to detect cosmic rays have sensitivity to such a shower. As an upper limit on the expected flux, assume that all of the dark matter consists of strangelets. The density of dark matter in our region of space is about g/cm . Strangelets of radius .01 to 10 cm would then have a number density of cm . The typical collision velocity would be that of the sun's velocity due to galactic rotation, about cm/sec. This results in a limit on the flux reaching the earth of cm sec , depending on size.
One such experiment was originally intended to search for pulsars in the crab nebula. It ran for 112 hours, and was set to trigger on events lasting seconds. A reanalysis of the data to search for strangelet events required a `burst' of 12 events to arrive within seconds. This corresponds to the transit time of a strangelet through the part of the atmosphere from which events could be detected. Producing 12 events from random fluctuations would require a fluctuation of . From this analysis the upper limit on the flux of strangelets is cm sec , for strangelets ranging from g. This is below the upper limit from the quick estimate above.
Each of the other experiments have sensitivities to strangelets of a particular size, covering an overall range from g to 250 g. Each places a limit on the total flux of strangelets of a given mass. When compared with the upper limit from the estimate above, the experiments are virtually all consistent with that limit. Experiments designed specifically for strangelet detection should be able to place much stricter limits.