Article

Study of saturation of CR39 nuclear track detectors at high ion fluence and of associated artifact patterns

Department of Physics, University of Nevada, Reno, Reno, Nevada, United States
Review of Scientific Instruments (Impact Factor: 1.58). 02/2007; 78(1):013304. DOI: 10.1063/1.2400020
Source: PubMed

ABSTRACT The occurrence of saturation in CR39 solid state nuclear track detectors has been systematically studied as a function of the incident ion (alpha particles and laser-accelerated protons) fluence and the etching time. When overexposed (i.e., for fluences above approximately 10(8) particles/cm(2)) and/or overetched, the CR39 detectors enter a saturated regime where direct track counting is not possible anymore. In this regime, optical measurements of saturated CR39 detectors become unreliable as well, since the optical response of the saturated detectors with respect to the ion fluence is highly nonlinear. This nonlinear optical response is likely due to scattering from the surface of irregular clumping patterns which have a diameter approximately 20 microm, i.e., ten times larger than the diameter of individual tracks. These patterns, which aggregate many individual tracks, are observed to develop in highly saturated regimes. For fluences typical of high energy short pulse laser experiments, saturation occurs, inducing the appearance of artifact ringlike structures. By careful microscopic analysis, these artifact ring patterns can be distinguished from the genuine rings occurring below saturation and characteristic of low energy laser accelerated proton beams.

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Questions & Answers about this publication

  • Kirk Flippo added an answer in Nuclear Chemistry:
    CR-39 detectors can be used to determine radon concentrations,is there any other application of CR-detectors?
    Radiation and health Physics
    Kirk Flippo · Los Alamos National Laboratory
    Here is a paper on using CR-39 near saturation. As Afshan points out CR-39 is used in laser-ion acceleration experiments (especially for low yields), it is also used on the Nation Ignition Laser facility in the Magnetic Recoil Spectrometer (run by MIT), as well as a neutron diagnostic, or alpha detector. Radiochromic Film (a self developing film) is used for higher flux radiography of ion beams, and in general radiotherapy applications at hospitals. A NOTE OF CAUTION, Pons and Fleishman (http://en.wikipedia.org/wiki/Cold_fusion) used CR-39 in their now (in)famous cold fusion experiments to detect neutrons. These erroneous results were likely (IMHO) due to a bad batch of detectors. The vendor matters in using CR-39, as does the need for etching controls on all batches. Homolite, another CR-39 vendor does not process their polymer for these types of applications, and no QA is done to assure the batch will not give you tracks when not exposed to any radiation, so buyer beware!