Nuclear Radiation Unit
Department of Physics and Materials Science
City University of Hong Kong
Tat Chee Ave, Kowloon Tong, Hong Kong
Email: apnru@cityu.edu.hk

Page last modified on 10-Nov-2009

  

 

on 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). Some examples of applications are design of track-etch templates for micro- and nano-fabrication, hole engineering and track membrane technology, radiobiological dosimetry, radon dosimetry and earth science applications.
Resources

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.

Book chapter: Nikezic, D., Yu, K.N., "Computer Simulation of Radon Measurements with Nuclear Track Detectors", 2007, in Computer Physics Research Trends, Ed. S. J. Bianco, (Nova Science Publishers: New York), p. 119-150. (download pdf version) (purchase book)

Freeware program (TRACK_TEST) 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 1.0) to determine the optical appearance of alpha-particle tracks in the CR-39 SSNTD: Click here to go to the download page. 

 

Highlights of Research:
Fabrication of micro-collimators
 

A micro-collimator is inserted between the a-particle source and the support substrate so only those a particles close to normal incidence onto the micro-collimator can pass through.

Image of the micro-collimator.

A thin PADC film was irradiated by 5 MeV a particles through a “macro-collimator”. This PADC film with latent tracks was then further etched in aqueous NaOH solution to form the micro-collimator with a thickness of 15 mm and etched-through air channels were all confined to a circular area with 1 mm diameter.

Publication:

Choi, V.W.Y., Yum, E.H.W., Yu, K.N., 2009. Micro-collimator fabricated by alpha-particle irradiation of polyallyldiglycol carbonate polymer film and subsequent chemical etching. Nuclear Instruments and Methods in Physics Research A, doi:10.1016/j.nima.2009.10.120 (in press)

Fabrication of cylindrical micro wires

Compact copper wire

Hollow copper cylinder

A polycarbonate membrane with a single heavy ion track (11.3 MeV/u U-238) was inserted into an electrolytic cell consisting of two cell halves with flat sealing surfaces facing the central membrane. The membrane was etched on both sides with 5 M NaOH plus 1 vol.% of Dowfax 2A1 surfactant at 41.5oC. The resulting channel was electro-replicated with copper. Electro-replication at 10 nA limiting current results in a hard, compact, polycrystalline copper wire; while electro-replication at 100 nA limiting current results in a hard, hollow polycrystalline copper cylinder.

Publication:

Man, L.C.T., Apel, P., Cheung, T., Westerberg, L., Yu, K.N., Zet C., Spohr R., "Influence of a surfactant on single ion track etching. Preparing and manipulating cylindrical micro wires", 2007, Nuclear Instruments and Methods in Physics Research B, 265, 621–625.

 

 

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