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The $^3$He($\alpha$,$\gamma$)$^7$Be reaction is a widely studied nuclearreaction; however, it is still not understood with the required precision. Ithas a great importance both in Big Bang nucleosynthesis and in solar hydrogenburning. The low mass number of the reaction partners makes it also suitablefor testing microscopic calculations.  Despite the high number of experimental studies, none of them addresses the$^3$He($\alpha$,$\gamma$)$^7$Be reaction cross sections above 3.1-MeVcenter-of-mass energy. Recently, a previously unobserved resonance in the$^6$Li(p,$\gamma$)$^7$Be reaction suggested a new level in $^7$Be, which wouldalso have an impact on the $^3$He($\alpha$,$\gamma$)$^7$Be reaction in theenergy range above 4.0 MeV. The aim of the present experiment is to measure the$^3$He($\alpha$,$\gamma$)$^7$Be reaction cross section in the energy range ofthe proposed level.  For this investigation the activation technique was used. A thin windowgas-cell target confining $^3$He gas was irradiated using an $\alpha$ beam. The$^7$Be produced was implanted into the exit foil. The $^7$Be activity wasdetermined by counting the $\gamma$ rays following its decay by a well-shieldedhigh-purity germanium detector.  Reaction cross sections have been determined between $E_{cm} = 4.0 - 4.4$ MeVwith 0.04-MeV steps covering the energy range of the proposed nuclear level.One lower-energy cross-section point was also determined to be able to comparethe results with previous studies.  A constant cross section of around 10.5 $\mu$barn was observed around the$^7$Be proton separation energy. An upper limit of 45 neV for the strength of a$^3$He($\alpha$,$\gamma$)$^7$Be resonance is derived.

Cross section of $^3$He($\alpha$,$\gamma$)$^7$Be around the $^7$Be proton separation threshold