MARIACHI, the Mixed Apparatus for Radar Investigation of Cosmic-rays of High Ionization, is an apparatus for the detection of ultra-high-energy cosmic rays (UHECR) via bi-static radar interferometry using VHF transmitters.
MARIACHI is also the name of the research project created and directed by Brookhaven National Laboratory (BNL) on Long Island, New York, initially intended to verify the concept that VHF signals can be reflected off the ionization patch produced by a cosmic ray shower.
[1] Project emphasis subsequently shifted to the attempted detection of radio wave reflections from a high energy ionization beam apparatus located at BNL's NASA Space Radiation Laboratory.
[3] The MARIACHI project, being in essence a public outreach project for high school and undergraduate students more than a full-scale science experiment, has continued in a sporadic fashion since its conception in the late 2000s.
The main researcher behind MARIACHI is Helio Takai (Brookhaven National Laboratory, Stony Brook University, as of 2019 Pratt Institute).