Improvement of charge resolution for high Z/β particles in CR-39 nuclear track detectors by means of two-step etching technique

S. Kodaira, S. Naka, N. Yasuda, H. Kawashima, M. Kurano, S. Ota, Y. Ideguchi, Nobuyuki Hasebe, K. Ogura

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    We verified that the two-step etching method of the combination of pre-etching with PEW (Potassium hydroxide + Ethanol + Water) solution and post-etching with NaOH solution makes drastic improvement of charge resolution for high Z/β particles (Z: nuclear charge, β: velocity) in CR-39 nuclear track detectors. Detectors were exposed to several heavy ions from Ne to Kr with the energies of <500 MeV/n at HIMAC (Heavy Ion Medical Accelerator in Chiba). The optimum etching conditions were determined to be a pre-etching of PEW solution with concentration of 60 wt% of ethanol for 40 min and a post-etching of 7N NaOH for 12 h. This resulted in a charge resolution for Kr (Z/β ∼ 60) of 0.18 c.u. (charge units). The Z/β detection threshold was increased as a function of ethanol concentration in PEW pre-etching solutions. We found that the two-step etching method would be useful technique for the precise charge identification by a single track measurement. The 60 wt% ethanol concentration in PEW would be adequate selection for the purpose of trans-iron nuclei measurement discriminating abundant light nuclei in galactic cosmic rays.

    Original languageEnglish
    Pages (from-to)36-41
    Number of pages6
    JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
    Publication statusPublished - 2012 Mar 1



    • Charge resolution
    • CR-39
    • Etching
    • Galactic cosmic rays
    • High Z/β particles
    • NaOH
    • Nuclear track detector
    • PEW
    • Trans-iron nuclei

    ASJC Scopus subject areas

    • Instrumentation
    • Nuclear and High Energy Physics

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