Coherent Pion Pairs from Heavy-Ion Collisions
  The degree to which a nucleus can act as a source for coherent pion pairs is investigated for intermediate-energy heavy-ion collisions. Creation through both isovector and isoscalar channels is considered. Two experimental signals are proposed for evidence of two-pion coherent production, two-pion enhancement and the focusing of outgoing pions along the beam axis. 
Scott Pratt and Kevin Haglin