Speaker
Description
Earth-skimming tau neutrinos in the PeV–EeV range can be caught two ways. Radio antennas (GRAND) spread cheaply over thousands of square kilometers, as the rarest, most energetic events demand, and register the shower's electromagnetic component. Particle detectors packed across a canyon (TAMBO) cover far less ground, reach well below the radio threshold, and sample the full particle content. They would also share the roads, the crew and the sky. The question is whether one mountain will hold both. It will. We present Oroscope (github.com/mbustama/oroscope), an open tool that answers by searching real terrain. It sweeps an elevation map for buildable ground, then looks out from each surviving patch: right target, right distance and direction, enough rock behind it? It scores candidates and reports where each rejected one was lost. One engine serves GRAND and TAMBO (and leaves room to add other detection technologies): different numbers, same questions. Co-location is settled by the ground itself, before any physics: a hillside has one steepness; the two experiments want different steepness. What each needs to see is in no conflict: one hillside serves both views. We have identified candidate ground in the Peruvian Andes: along the Colca Valley in Arequipa, in the Callejón de Huaylas in Áncash, and around Cajatambo in Lima. Where both arrays have been searched at full resolution, 73–81% of the particle array's usable ground also serves the radio array. Their masks look nothing alike: one large radio site, tens of small particle sites on steep ground inside it. The share moves with array design; the particle array limits it, and the radio array pays almost nothing.