Exposure of CR-39 plastic to the bevalac Mn beam
TL;DR: In this paper, the CR-39 plastic track detector has been exposed to a fragmented beam of 25Mn nuclei in order to calibrate plastics used in a recent ballon flight.
About: This article is published in Nuclear Tracks and Radiation Measurements.The article was published on 1984-01-01. It has received 1 citations till now. The article focuses on the topics: CR-39.
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TL;DR: In this article, the minor axes of the elliptic etch pits were measured by a Leitz Ortholux microscope and the measured double-cone charge resolution was found to be 0.20e.
Abstract: 1.88A GeV56Fe beam of Lawrence Berkeley Laboratory BEVALAC irradiated at an angle 30° to the stack, composed of Al target and CR-39 (DOP) solid-state nuclear-track detector. These polymer sheets were etched in 6.25N NaOH solution at 70°C for 48 hours. The minor axes of the elliptic etch pits were measured by a Leitz Ortholux microscope. The measured projectile fragmentation cross-section for nuclei of chargeZ ranging from 21 to 25 is in approximate agreement with the calculated result from the semi-empirical nuclear fragmentation model after Wilson, Townsend and Badavi. The existence of trans Fe nuclei was noticed. The measured double-cone charge resolution was found to be 0.20e.
4 citations
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TL;DR: In this paper, a commercially available, optically clear, amorphous, thermoset plastic in which nuclear particle tracks can be revealed by etching in a hot NaOH solution is described.
514 citations
315 citations
TL;DR: In this article, a stack of plastic CR-39 and nuclear emulsions was exposed at a vertical cut-off rigidity of 10.3 GV and an atmospheric depth of 7 g/cm2 for 30 h in May, 1979.
39 citations
TL;DR: In this paper, it is shown that this limitation can be overcome with a new nuclear track detector, CR-39(DOP), and that the charge resolution of this detector exceeds that of any other, including semiconductor diodes.
Abstract: It is pointed out that detectors of the energy loss of penetrating charged particles are widely used for particle identification. These measurements are hampered, however, by fluctuations in the amount of energy deposited within the detector. It is shown that this limitation can be overcome with a new nuclear track detector, CR-39(DOP), and that the charge resolution of this detector exceeds that of any other, including semiconductor diodes.
33 citations
TL;DR: In this paper, a series of CR-39 plastic track detectors with large collecting power at the summit of White Mountain, California (603 g/${\mathrm{cm}}^{2}$) were deployed and analyzed.
Abstract: The inspiration for this experiment was the widely acknowledged peculiar nature of the "Centauro" class of ultrahigh-energy interactions discovered at Mt. Chacaltaya about a decade ago by a Brazil-Japan collaboration. The rate of Centauro events is quite low, \ensuremath{\sim}0.02 ${\mathrm{m}}^{\ensuremath{-}2}$${\mathrm{yr}}^{\ensuremath{-}1}$. Among the proposed explanations is the possibility that they might be initiated by a highly charged primary particle. To look for such particles we deployed a series of CR-39 plastic track detectors with large collecting power at the summit of White Mountain, California (603 g/${\mathrm{cm}}^{2}$). Two experiments have been completed and analyzed: a single layer with a 10-${\mathrm{m}}^{2}$yr exposure, and three layers in coincidence with a 0.025-${\mathrm{m}}^{2}$yr exposure. In the first experiment, the single layer was adopted to maximize the collecting area at some sacrifice in velocity information. The results demonstrate the superiority of CR-39 as a detector of highly ionizing particles ($\frac{Z}{\ensuremath{\beta}}\ensuremath{\gtrsim}30$) and its particular suitability as a collector of very rare particles. The performance of the plastic was evaluated by examining the high density of tracks due to slow, light ions. The low-energy spectra of nuclei with $Z\ensuremath{\le}3$ have been measured and are found to be consistent with spectra calculated from a model where the source of ions is atmospheric collisions of energetic hadrons. This is the first time that energetic Li has been identified at mountain altitude and that enough He has been seen to permit measurements of its energy spectrum. A density \ensuremath{\sim} ${10\mathrm{m}}^{\ensuremath{-}2}$ of fast particles with $Z\ensuremath{\ge}4$ found in individual layers is consistent with the exposure received in a 10-hour commercial jet flight. A fast-scanning method was used to examine the entire single-layer array. In the interval $30\ensuremath{\lesssim}\frac{Z}{\ensuremath{\beta}}\ensuremath{\lesssim}100$, no events were found, from which we infer an upper limit of 0.4 ${\mathrm{m}}^{\ensuremath{-}2}$${\mathrm{yr}}^{\ensuremath{-}1}$ (95% C.L.) on the flux of electrically charged particles with $\frac{Z}{\ensuremath{\beta}}\ensuremath{\sim}30 \mathrm{to} \ensuremath{\sim}100$ and on the flux of superheavy magnetic monopoles with $\ensuremath{\beta}\ensuremath{\gtrsim}0.02$. Two objects were located which, if they are indeed tracks, would correspond to particles with $\frac{Z}{\ensuremath{\beta}}\ensuremath{\gtrsim}100$, with abundance \ensuremath{\sim}0.2 ${\mathrm{m}}^{\ensuremath{-}2}$${\mathrm{yr}}^{\ensuremath{-}1}$. Without sheets in coincidence, it is impossible to distinguish these objects from certain flaws in the plastic. A new detector, with three layers interleaved with absorbers and with an area of 20 ${\mathrm{m}}^{2}$, will correct this shortcoming and be able to measure the spectra of light elements to higher energies as well.
26 citations