(1976). Nuclear Tracks in Solids (Principles and Applications) Nuclear Technology: Vol. 30, No. 1, pp. 91-92.

Nuclear Tracks in Solids (Principles and Applications)

Fragmentation processes in nuclear reactions

Part 1 describes the elements of solid-state nuclear track detectors (SSNTDs) including detector materials (crystals, glasses, and polymers), recordable particles (protons, α-particles, fission fragments, heavy ions, neutrons, and exotic particles), track formation mechanisms, track etching, particle identification, and track measuring instruments. Part 2 describes applications in nuclear physics, astrophysics, cosmic-ray physics, fission track dating and geothermal chronology, medical science, radiation dosimetry, Rn monitoring, environmental sciences, and nanotechnology. Attention is paid to the newly emerged fields: laser acceleration, laser inertial-confinement fusion, nuclear forensics, and safeguards. The internal structure in this chapter is closely linked between materials, particles, and applications; when describing one of these, the other two are introduced. The above structure of this chapter was organized for the benefit of the reader by providing the current principles and techniques together with the broad research fields of application of SSNTDs. Numerous detector parameters and applications are provided. Essential literature references are provided for detailed information on breakthroughs and recent advances.

Solid-state nuclear track detectors

High-energy collisions with atomic nuclei: The experimental results

Using CR-39 nuclear track detectors and an automated scanning system, we have studied the behavior of projectile fragments with charges 8\ensuremath{\le}${\mathit{Z}}_{\mathit{F}}$\ensuremath{\le}13 produced in interactions of 14.5A GeV $^{28}\mathrm{Si}$ nuclei with Pb and Cu targets. Both nuclear and electromagnetic spallation contribute to fragmentation of beam nuclei in Pb and Cu. The total charge-changing cross sections of nuclear projectile fragments with 9\ensuremath{\le}${\mathit{Z}}_{\mathit{F}}$\ensuremath{\le}13 interacting in Pb are found to be enhanced by 10 to 30 % relative to charge-changing cross sections of stable nuclides. The enhancement occurs primarily in interactions with large loss of charge. In Cu the charge-changing cross sections of secondaries show no significant excess. The mean free path of secondary fragments shows no dependence on the distance from the point of origin. This result rules out at 95% confidence level the production of nuclear fragments with interaction cross sections enhanced by a large factor as conjectured by some workers, but the result is consistent with a two-component model in which \ensuremath{\sim}30% of secondary beams are off-stability isotopes with total cross sections enhanced by \ensuremath{\sim}25%. Our measurements of angular distributions of projectile fragments showed that the transverse momentum distributions are similar to those measured at (1--2)A GeV. The charge pickup cross section of 14.5A GeV Si is measured to be 0.07--1.3 mb in Pb and \ensuremath{\le}0.9 mb in Cu, which is of the same order of magnitude as that measured at \ensuremath{\sim}1A GeV.

Behavior of nuclear projectile fragments produced in collisions of 14.5A GeV 28Si with Pb and Cu targets.

When fragments of $1.85A$-GeV $^{40}\mathrm{Ar}$ projectiles are observed in a CR-39 etched track detector, anomalously short mean free paths of secondary nuclei with $11g~Zg~17$ are found within the first 2 cm after their production, at \ensuremath{\sim} 3 standard deviations. This confirms the previous reports of this "anomalon" effect in nuclear emulsion. The data can be fitted by the hypothesis that \ensuremath{\sim} 3.6% of the secondaries have a mean free path of \ensuremath{\sim} 1.0 cm and infinite lifetime.

Observation of Anomalously Short Mean Free Paths of Projectile Fragments of 1 . 8 5 A -GeV Ar 40 in CR-39 Etched Track Detector

Using dioctyl-phthalate-doped CR-39 plastic track detectors with charge resolution ${\ensuremath{\sigma}}_{Z}\ensuremath{\approx}0.06e$, the authors have made the first dynamic search for fractionally charged particles bound to nuclei. They find, from charge measurements in the first \ensuremath{\sim} 2 cm after production, that no more than 3 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}3}$ (95% confidence level) of the projectile fragments of 1.85-GeV/u $^{40}\mathrm{Ar}$ interactions with $10l~Zl18$ have charges differing from an integer by as much as $0.3e$. This rules out explanations of anomalons based on models in which the anomalons have nonintegral charge in such charge range.

Search for nonintegrally charged projectile fragments in relativistic nucleus-nucleus collisions

We present measurements of charge resolution in the plastic track detectors CR39(DOP) and Tuffak polycarbonate over the region 10≤ Z β ≤105 , determined from plastic stacks exposed to projectile fragments of 1.29 GeV u 139La, 1.45 GeV u 84Kr, and 1.70 GeV u 56Fe produced by nuclear interactions within the stacks, and to 0.96 GeV u 238U and 1.0 GeV u 197Au ions. The charge resolution obtained is shown to be comparable to the irreducible limit set by fluctuations in energy loss and is consistent with that expected of a track-formation model based on the effects of both K-shell ionization and restricted energy loss.

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Charge resolution of plastic track detectors used to identify relativistic nuclei

Identification of relativistic nuclei with 10 ⪷ Z ⪷ 92

http://deepblue.lib.umich.edu/bitstream/handle/2027.42/24979/0000406.pdf?sequence=1

M. L. Tincknell

Papers

Observation of Anomalously Short Mean Free Paths of Projectile Fragments of 1 . 8 5 A -GeV Ar 40 in CR-39 Etched Track Detector

Search for nonintegrally charged projectile fragments in relativistic nucleus-nucleus collisions

Charge resolution of plastic track detectors used to identify relativistic nuclei

Identification of relativistic nuclei with 10 ⪷ Z ⪷ 92

Calibration of Tuffak polycarbonate track detector for identification of relativistic nuclei