Energy distributions of photons in the 12C(π−, 2γ) reaction

doi:10.1016/0370-2693(80)90208-7

Physics Letters B

Volume 96, Issues 1–2, 20 October 1980, Pages 43-46

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Abstract

We have measured the photon energy spectra, angular distribution, and total branching ratio for the ¹²C(π⁻, γγ)X process for stopped pions. The branching ratio for photons with energies higher than 17 MeV is (1.2 ± 0.2) × 10⁻⁵, which is slightly lower than that of an experiment published recently. The energy distributions of the photons exhibit a shape, characteristic of a momentum-dependent bremsstrahlung mechanism, in agreement with a recent calculation based on a conventional nuclear model with no enhancement in the pion field.

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^☆: We would like to acknowledge many helpful discussions with D. Beder and P. Christillin and thank them for providing us with their calculations prior to publication. We also thank J. Deutsch for several helpful conversations. We are grateful to the TRIUMF staff for their efficient operation of the accelerator and to Mrs. Meyer and Holdermann, Universität Basel, for their careful typing of the final manuscript. This work was supported in part by the Natural Sciences and Engineering Research Council of Canada.

¹: Now at CEN-Saclay, DPhN-HE, 91190 Gif-sur-Yvette, France.

²: Now at Department of Physics, Carnegie-Mellon University, Pittsburgh, PA 15213, USA.

³: Address 1979–1980: Institut für Physik der Universität Basel, Basel, CH-4056 Switzerland.

⁴: Now at MS-540, Los Alamos Scientific Laboratory, Los Alamos, NM 87545, USA.

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Energy distributions of photons in the 12C(π−, 2γ) reaction☆

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