Unseen Armenia: Peering Up through the Depths: The Avan Salt Mine
By Hovsep Daghdigian
YEREVAN — The Avan district of Yerevan was once a separate village, dating back to the pre-Christian era. As Yerevan expanded during Soviet times, Avan was incorporated into the city of Yerevan. Within Avan there are a number of old churches; the most interesting perhaps being the partially ruined 5-6th century cathedral. This was the seat of a rival Catholicos espousing the Byzantine creed, in opposition to Armenian Apostolic creed. Also within Avan is the privately owned Avan Salt Company, producing both table salt and rock salt from its mine. The salt deposit dates to ancient geologic times when the region was covered with water, or perhaps a sea. As the water evaporated it left salt deposits that are now extracted from deep underground.
Over three decades ago the Yerevan Physics Institute (YerPhI) Experimental Division established a low-background radiation laboratory in the Avan salt mine where they conducted sensitive measurements investigating rare processes in both fundamental and applied physics. The laboratory was carved out of walls of pure salt creating a living room size chamber in the mine. Both YerPhI’s Experimental Division and the Cosmic Ray Division (CRD) operate sensitive cosmic ray particle detectors for which a low background radiation environment is essential. The scientists are interested in only the most energetic particles that can penetrate to the depth of the mine. Surrounding the laboratory are walls and a ceiling of high purity salt, with very low background radioactivity that would otherwise interfere with the sensitive measurements. If the laboratory were on the surface of the earth, abundant low energy cosmic ray particles, and minute sources of radioactivity on the surface, would interfere with the sensitive measurements and mask out the data that the scientists are actually interested in.