APPLICATION OF A PULSED SLOW-POSITRON BEAM TO LOW-DENSITY POLYETHYLENE FILM |
| E. Hamadaa,1, N. Oshimab, K. Katoha, T. Suzukic, H. Kobayashic, K. Kondoc, I. Kanazawad and Y. Itoe aDepartment of Radiological Sciences, Ibaraki Prefectural University of Health Sciences Ami, Ibaraki 300-0394, Japan bAtomic Physics Laboratory, The Institute of Physical and Chemical Research (RIKEN) Wako, Saitama 351-0198, Japan cHigh Energy Accelerator Research Organization (KEK) Tsukuba, Ibaraki 305-0801, Japan dDepartment of Physics, Tokyo Gakugei University, Koganei, Tokyo 184-0015, Japan eResearch Center for Nuclear Science and Technology, The University of Tokyo Tokai, Ibaraki 319-1106, Japan |
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| A pulsing system for a slow-positron beam was applied to study the
region near the surface of low-density polyethylene film using
positron-annihilation lifetime measurement. The lifetime and intensity
of ortho-positronium near the surface were measured as a
function of the incident positron energy (1.6-9.1 keV). The size of
intermolecular spaces in the surface region (~1500 nm) was larger
than that in the bulk region. This tendency was especially strong in
the region around 200 nm below the surface. On the other hand, the
intensity of ortho-positronium decreased at lower incident
positron energies, which was attributed to a decrease in the density of
the spur electrons and/or an increase in the number of reemitted
positrons from the surface. 1corresponding author |
| DOI: 10.12693/APhysPolA.99.373 PACS numbers: 78.70.Bj |