Medium modifications of the pion-pion interaction: A search for double pionic fusion in14N+d16O+2

Abstract

Double pion production in the reaction 14 Nϩd→ 16 O*ϩ2 has been investigated 99 MeV above the 2 0 threshold in the center-of-mass frame by recoil detection. Upper limits ͑2 standard deviations͒ to the differential cross sections for producing 16 O in a particle-stable state and pion pairs in the invariant mass range of 270 to 310 MeV/c 2 , d/d⍀(0°) c.m. Ͻ1.7 nb/sr and d/d⍀(180°) c.m. Ͻ1.3 nb/sr, were obtained. For invariant masses above 310 MeV/c 2 an upper limit to the cross section of 7 nb was obtained, assuming a constant production matrix element.