Author/Authors :
N. Willis، نويسنده , , Y. Le Bornec، نويسنده , , A. Zghiche، نويسنده , , C. Wilkin، نويسنده , , R. Wurzinger، نويسنده , , O. Bing، نويسنده , , C. M. Boivin، نويسنده , , P. Courtat، نويسنده , , R. Gacougnolle، نويسنده , , F. Hibou، نويسنده , , J.M. Martin، نويسنده , , P. F. Plouin، نويسنده , , B. Tatischeff، نويسنده , , J. Yonnet، نويسنده ,
Abstract :
The cross section and tensor analysing power t20 of the dd → 4Heη reaction have been measured at six c.m. momenta, 10 ⩽ pη ⩽ 90 MeV/c. The threshold value of t20 is consistent with 12, which follows from parity conservation and Bose symmetry. The much slower momentum variation observed for the reaction amplitude, as compared to that for the analogous pd → 3Heη case, strongly suggests the existence of a quasi-bound state in the η4He system and simple optical model fits tentatively indicate that this might also be the case for η3He.
