Direct measurement of the Chudakov effect.
Experimental results for the restricted energy loss of pairs created from 1-178 GeV photons in a thin Au target and subsequently passing a CCD detector are presented. It is shown that pairs--when detected close to the creation vertex--suffer a reduced energy loss due to the internal screening of the charges constituting the pair. Furthermore, the ability to measure directly the energy of the pair by calorimetry enables a comparison with theory as a function of energy. The observed phenomenon is in good qualitative agreement with general expectations from the Chudakov effect but indicates a quantitative disagreement with either of two mutually disagreeing theories.
Department of Physics and Astronomy, University of Aarhus, Denmark.
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Virkus
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Thomsen
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Uggerhøj
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Uggerhøj
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Ballestrero
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Sona
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Mangiarotti
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Ketel
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Dizdar
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Pagliarone