Further search for a neutral boson with a mass around 9 MeV/c2

Two dedicated experiments on internal pair conversion (IPC) of isoscalar M1 transitions were carried out in order to test a 9 MeV/ c 2 X -boson scenario. In the 7 Li(p,e + e - ) 8 Be reaction at 1.1 MeV proton energy to the predominantly T = 0 level at 18.15 MeV, a significant deviation from IPC was observed at large pair correlation angles. In the 11 B(d,ne + e - ) 12 C reaction at 1.6 MeV, leading to the 12.71 MeV 1 + level with pure T = 0 character, an anomaly was observed at ~9 MeV/ c 2 . The compatibility of the results with the scenario is discussed.