Observation of the Charge Symmetry Breaking d + d -> 4He + pi0 Reaction Near Threshold

We report the first observation of the charge symmetry breaking d + d -> 4He + pi0 reaction near threshold at the Indiana University Cyclotron Facility. Kinematic reconstruction permitted the separation of 4He + pi0 events from double radiative capture 4He + gamma + gamma events. We measured total cross sections for neutron pion production of 12.7 +- 2.2 pb at 228.5 MeV and 15.1 +- 3.1 pb at 231.8 MeV. The uncertainty is dominated by statistical errors.Comment: 7 pages, 2 figures, plain Te

Has charge symmetry breaking been observed in the d d -> alpha pi0 reaction?

Estimates are made of the d d -> alpha gamma gamma production cross sections in a model where each neutron-proton pair in the beam and target initiates an n p -> d gamma reaction. This approach, which successfully reproduces observables in two-pion production at intermediate energies, suggests that direct two-photon production could provide a very significant background to the measurement of the charge-symmetry-breaking (CSB) reaction d d -> alpha pi0. A non-vanishing CSB cross section has been reported which might be confused with such two-photon production under the given experimental conditions.Comment: 9 pages, ReVTEX, 2 figures, submitted to Phys. Rev. Let

Mise en évidence de la diffusion inélastique des rayons γ par les électrons liés de l'atome

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Contribution du champ électrique des noyaux à la diffusion élastique des γ du 60Co

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Diffusion élastique des rayons γ de 1,12-1,17-1,33 et 2,62 Mev

Comparison of experimental and theoretical results in order to show the Delbruck effect. The conclusion is negative for 1,12 and 1,33 MeV, but it is more difficult to give any conclusion for 2, 62 MeV. For 1,17 MeV a possible intervention of the inelastic scattering is found.Comparaison de résultats expérimentaux et de calculs théoriques récents en vue de mettre en évidence l'effet Delbruck. La conclusion est négative pour 1,12 et 1,33 MeV, mais plus difficile à donner pour 2,62 MeV. On trouve pour 1,17 MeV une intervention possible de la diffusion inélastique