GRAND is an array of position sensitive proportional wire chambers (PWCs) located at 86.2 deg W, 41.7 deg N at an elevation of 220 m and is adjacent to the campus of the University of Notre Dame. The geometry of the PWCs allows the angles of the charged secondary tracks to be measured to +/- 0.3 deg in each of two orthogonal planes. Muons are 99% differentiated from electron tracks in the 83 square meters of muon detectors.

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 5 (HE part 2), pages 1577-1580