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The halo nucleus [sup 6]He has been studied in a pionic fusion experiment at the CELSIUS storage ring facility in Uppsala. The [sup 6]He nuclei were produced in reactions with a deuteron beam incident on a [sup 4]He jet target 0.9-5.4 MeV above threshold in the center-of-mass frame. The [sup 6]He ions were detected in a ΔE-E solid-state detector telescope inserted into the CELSIUS ring. The aim of the experiment was to investigate, in particular, the high-momentum part of the halo wave function by measuring the total and differential cross sections of the reaction d + [sup 4]He → [sup 6]He + π[sup +]. [ABSTRACT FROM AUTHOR]

Abstract: The halo nucleus 6He has been studied in a pionic fusion experiment at the CELSIUS ring in Uppsala. The aim of the experiment was to investigate, in particular, the high-momentum part of the halo wave function by measuring the differential cross section for the 4He(d, 6He) reaction 0.6, 1.2 and 5.0 MeV above threshold in the centre-of-mass frame. The 6He ions were detected in a solid-state detector telescope inserted into the ring vacuum. The result for the total cross section is, respectively, 22(1), 38(1) and 57(9) nb with a common systematic uncertainty of . The differential cross section is clearly anisotropic: , and at the same three energies. The preferred direction of emission for the pion is parallel to the momentum of the 4He ion in the initial state. In terms of a simple model for the reaction the results depend sensitively on the state of motion of the centre of mass of the halo relative to that of the core. [Copyright &y& Elsevier]