New measurement of the rare decay eta -> pi(0)gamma gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

A2 Collaboration MAMI, B. M. K. Nefkens*, S. Prakhov, P. Aguar-Bartolome, J. R. M. Annand, H. J. Arends, K. Bantawa, R. Beck, V. Bekrenev, H. Berghaeuser, A. Braghieri, W. J. Briscoe, J. Brudvik, S. Cherepnya, R. F. B. Codling, C. Collicott, S. Costanza, I. V. Danilkin, A. Denig, B. DemissieM. Dieterle, E. J. Downie, P. Drexler, L. V. Fil'kov, A. Fix, S. Garni, D. I. Glazier, R. Gregor, D. Hamilton, E. Heid, D. Hornidge, D. Howdle, O. Jahn, T. C. Jude, V. L. Kashevarov, A. Kaeser, I. Keshelashvili, R. Kondratiev, M. Korolija, M. Kotulla, A. Koulbardis, S. Kruglov, B. Krusche, V. Lisin, K. Livingston, I. J. D. MacGregor, Y. Maghrbi, J. Mancel, D. M. Manley, E. F. McNicoll, D. P. Watts

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A new measurement of the rare, doubly radiative decay eta -> pi(0)gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta -> pi(0)gamma gamma), on the two-photon invariant-mass squared, m(2)(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta -> pi(0)gamma gamma) = (0.33 +/- 0.03(tot)) eV, are based on analysis of 1.2 x 10(3) eta -> pi(0)gamma gamma decays from a total of 6 x 10(7) eta. mesons produced in the gamma p -> eta p reaction. The present results for d Gamma(eta -> pi(0)gamma gamma)/dm(2)(gamma gamma) are in good agreement with previous measurements and recent theoretical calculations for this dependence.

Original languageEnglish
Article number025206
Number of pages9
JournalPhysical Review C
Issue number2
Publication statusPublished - 14 Aug 2014


  • MAMI
  • TAPS


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