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We have searched for neutrons from the 3‐body photon‐induced reaction 9Be + γ → α + α + n using bremsstrahlung produced by electrons from a 2‐MV Van de Graaff. The target was located within a block of beryllium surrounded by an array of 3He proportional counters embedded in paraffin. Based on energy and intensity calibrations of the accelerator and detector using the 9Be + γ → 8Be+n reaction, an upper limit of 93 nb (4σ) was placed on the cross section for neutron production between the 3‐body and 2‐body thresholds. This value is substantially below a previously experimental result using photoexcitation by a 142Pr gamma source and also below an earlier theoretical estimate. We suggest that bremsstrahlung due to beta rays between 1665 keV and the 2160‐keV end‐point of the 142Pr beta‐ray spectrum could account for the photoneutron yield in the 3‐body region that had previously been attributed to 142Pr gamma rays.

Search for Subthreshold Neutron Production in Be