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. 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.

Mariachi is a musical expression that dates back to at least 19th century Western Mexico. It is a tradition that can be defined by eight socio-musical elements: mariachi instrumentation and texture, musical genres and sub genres, performance methods and styles, singing styles and forms, dance styles, performative space, performance clothing, and the word "mariachi". Each element has its own history, originated at varying moments in time and in different regions of the Western Mexican countryside, and some, not all, had to have converged in order for the mariachi tradition to be what it has become.