Search for η-mesic Helium with the WASA-at-COSY detector Wojciech Krzemien, Pawel Moskal, Jerzy Smyrski and Magdalena Skurzok EPJ Web of Conferences, 37 (2012) 02003 Published online: 06 December 2012 DOI: 10.1051/epjconf/20123702003