Absence of spin dependence in the final state interaction of the d→p→He3η reaction

The deuteron tensor analysing power T20T20 of the d→p→He3η reaction has been measured at the COSY-ANKE facility in small steps in excess energy Q   up to Q=11 MeVQ=11 MeV. Despite the square of the production amplitude varying by over a factor of five through this range, T20T20 shows little energy dependence. This is evidence that the final state interaction causing the energy variation is not influenced by the spin configuration in the entrance channel. The weak angular dependence observed for T20T20 provides useful insight into the amplitude structure near threshold.