Ion Track Technology

Fast moving charged particles are known to produce trails of atomic disorder (usually referred to as nuclear tracks or ion tracks) in an immense variety of dielectric solids (including crystals, glasses, and high polymers), intermetallics, certain metals and amorphous metals, oxide conductors and superconductors. The more common commercial nuclear track materials include polycarbonate (marketed as Makrofol), polyallyldiglycol carbonate (marketed as CR-39) and cellulose nitrate (marketed as LR 115). Nuclear tracks have found many applications in different branches of science (for a recent review, see the review paper shown on the right).

Review paper: Nikezic, D., Yu, K.N., "Formation and Growth of Tracks in Nuclear Track Materials", 2004, Materials Science and Engineering R, 46 (3-5), 51-123. (download pdf version). 

"Different experimental methods have been established for the determination of the bulk etch rate. An excellent review of these methods and their advantages and disadvantages has been given by Nikezic and Yu (2004)." -- by D. Hermsdorf, M. Hunger, S. Starke and F. Weickert, Radiation Measurements 42 (2007) 1-7.

Freeware program (TRACK_TEST 2.1) to calculate alpha track parameters in the CR-39 and LR 115 SSNTDs: Click here to go to the download page. 

Freeware program (TRACK_VISION 2.1) to determine the optical appearance of alpha-particle tracks in the CR-39 SSNTD: Click here to go to the download page. 

Freeware program (TRACK_P 1.0) to calculate track parameters in PADC films (or commercial CR-39 detectors) caused by protons: Click here to go to the download page. 

It has been shown that detection and dosimetry of fast neutrons are possible with solid-state nuclear track detectors (SSNTDs). For this purpose, some converters can be placed between the neutron source and the SSNTD to facilitate the production of recoiled protons in the converter, which are further registered in the SSNTD. However, under such a condition, most information on the energy of the incident neutron will be lost. As such, it is valuable and pertinent to explore alternative methods to be able to record and reconstruct the energy of the incident neutrons. A theoretical feasibility study on neutron spectrometry with the polyallyldiglycol carbonate (PADC) solid-state nuclear track detector (SSNTD) was carried out [1].

A computer program for studying etched proton tracks in the PADC SSNTD was prepared [2]. The program provided visualization of track appearance as seen under the optical microscope in the transmission mode. Measurable track parameters were also determined and displayed and written in a data file. Three-dimensional representation of tracks was also enabled. Application of this software in neutron dosimetry for energy up to 11 MeV was demonstrated through the creation of a databank with a large number of tracks, which would be used to compare real-life tracks obtained in the PADC detector upon neutron irradiation. One problem was identified, viz., very similar tracks were obtained from protons with very different energies and incident angles, and strategies to solve this were proposed.

Examples of proton tracks in the PADC film detector. The tracks were generated by protons with energies between 0.5 and 5 MeV with incident angles of 90 deg, and corresponded to removed layers of 5 and 10 mm. Below each image, the diameter and the fraction of black portion of the track are shown (from top to bottom)

We proposed the "proxy equilibrium factor" or "F_p" method to determine F using bare LR 115 detectors. We found that the partial sensitivities ρ_i (with the unit m) of the LR 115 detector to ²²²Rn and its alpha emitting short-lived progeny, ²¹⁸Po and ²¹⁴Po, were equal! Equality of partial sensitivities enabled convenient measurements of F_p, which was defined as (f₁ + f₃) and was equal to the ratio between the sum of concentrations of the two alpha emitting radon progeny (²¹⁸Po+²¹⁴Po) to the concentration of radon gas (²²²Rn). We found F_p = (ρ/ρ_itC₀)-1, where ρ (track/m²) was the total track density on the detector, and t was the exposure time and C₀ (Bq/m³) was the concentration of ²²²Rn. F_p was found to be well correlated with F through the Jacobi room model.

Dependence of the equilibrium factor F on the proxy equilibrium factor F_p (= f₁ + f₃).