Low Energy Cross-Sections for Positron Interactions with Cyclic Hydrocarbons

G.P. Karwasza, D. Pliszkab, R.S. Brusaa and C. Perazzollia aDipartimento di Fisica, Università di Trento, 38050 Povo (TN), Italy bInstitute of Physics, Pomeranian Pedagogical Academy, 76-200 Słupsk, Poland

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Received: 20 09 2004;

We report total cross-section measurements for positron scattering on cyclic hydrocarbons: benzene, aniline, and cyclohexane. Measurements were done by an absolute transition method in the energy range 1.5-20 eV (0.4-20 eV for cyclohexane). High cross-sections for all measured molecules were observed at low energies. In the case of cyclohexane the cross-section in the zero energy limit tends to a constant value. In aniline a weakly accented peak slightly above the positronium formation threshold is observed. Similar but less visible bump was observed in the case of benzene. Measurement of total cross-sections in nitrogen and argon used for calibration of the apparatus are also presented.

DOI: 10.12693/APhysPolA.107.666 PACS numbers:34.85.+x, 39.90.+d