Affiliation: | Institut für Physik mit Ionenstrahlen, Ruhr-Universit?t Bochum, Bochum, Germany, DE Atomki, Debrecen, Hungary, HU Dipartimento di Fisica, Università di Milano and INFN, Milano, Italy, IT INFN, Padova, Italy, IT Dipartimento di Scienze Fisiche, Università Federico II and INFN, Napoli, Italy, IT Dipartimento di Fisica, Università di Genova and INFN, Genova, Italy, IT Dipartimento di Scienze Ambientali, Seconda Università di Napoli, Caserta and Napoli, Italy, IT Dipartimento di Fisica Sperimentale, Università di Torino and INFN, Torino, Italy, IT Laboratori Nazionali del Gran Sasso dell'INFN, Assergi, Italy, IT California Institute of Technology, Pasadena, CA, USA, US Osservatorio Astronomico di Collurania, Teramo, Italy, IT
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Abstract: | The stopping power of atomic and molecular deuterons in 3He gas was measured over the range E d = 10 to 100 keV using the 3He pressure dependence of the 3He(d,p) 4He reaction yield. At energies above 30 keV, the observed stopping power values are in good agreement with a standard compilation. However, near 18 keV the experimental values drop by a factor 50 below the extrapolated values of the compilation. In a simple model, the behavior is due to the minimum 1s↦2s electron excitation of the He target atoms (= 19.8 eV, corresponding to E d = 18.2 keV), i.e. it is a quantum effect, by which the atoms become nearly transparent for the ions. |