Cellulose Nitrate Track Detectors Research Articles

Response characteristics of cellulose nitrate track-detectors to radon and radon-daughter mixtures

The response of bare cellulose nitrate (CN) LR-115, type II (Kodak-Pathé), track detector exposed to various mixtures of radon and airborne radon-daughters is investigated. Under controlled irradiation conditions good linear correlation was obtained between through-etched track density ϱ and the radon-daughter accumulated exposure ϵa (in units of WL-h). It is shown that the calibration factor Δϵa/Δϱ for the CN LR-115, type II, track detector is an increasing function of the equilibrium ratios of the radon-daughter mixtures.

Influence of some characteristics of cellulose nitrate track detectors on their sensitivity to alpha particles

Influence of some characteristics of cellulose nitrate track detectors on their sensitivity to alpha particles

Neutron sensitivity of LR 115 SSNTD using different (n, α) radiators

The neutron sensitivity of Kodak-Pathé LR 115 II type cellulose nitrate track detectors with different (n, α) radiators was investigated by calculations and measurements. The α counting efficiency using an optical microscope is 95% and 92% for α particles with maximum energies of 2 and 1.5 MeV, respectively. When using an image analyser the etched through-tracks (holes) with diameter greater than 2 μm are counted. The efficiency then depends only on the original and removed layer thickness but not on the etching temperature within the range of 40 to 65°C and 2.5 to 6 N normality of the NaOH etchant. Efficiency varies from about 3 to 20% for alphas from the 6Li(n, α)T reaction if the removed layer lies in the range of ∼7 to 10 μm, and varies from ∼2 to 10% for 10B(n, α) 7Li reaction alphas when the layer removal is ∼8 to 10 μm.

Mechanism of particle track etching in polymeric nuclear track detectors

A mechanism of particle track etching in polymers is proposed, which is based on the assumption that a free reaction volume is required for enhanced chemical degradation in a particle track. The free reaction volume ν ∗ is supposed to be formed from the holes with a free volume ν f, which were produced in the latent track by release of gaseous products of radiolysis or post-irradiation reactions. The exponent in the empirical response function is considered to represent the ratio ν ∗/ν f . The influence of material parameters and etching conditions on the response function of cellulose nitrate track detectors is discussed in terms of the free reaction volume concept. The rapid energy transfer in macromolecules prior to bond cleavage suggests a linear dose dependence of the radiolysis product yield in a wide dose range. The radius restricted energy loss is favoured to be used in response functions from the point of view of radiation chemistry.

Optimum etching time for alpha-particle tracks in some cellulose nitrate track detectors

Optimum etching time for alpha-particle tracks in some cellulose nitrate track detectors

Long-range alpha emission inP-wave neutron induced fission of235U

The yield and energy distribution of long-range alpha-particles (lra) emitted from neutron-induced fission of235U have been measured at neutron energies; thermal, 125±12, 155±11, 185±10, 210±9, 240±9, 365±50 and 480±45 keV. The long-range alpha-particles were detected in cellulose nitrate track detector foils. Results showed an increase of about 50% in the yield at neutron energies in the region 150 keV≤E n≤220 keV as compared to that of thermal neutrons. A calculation has been carried out to extract thelra to binary fission ratio forp-wave neutron induced fission.

Sensitivity of cellulose nitrate track detectors in dependence on neutron energy

ABSTRACT This paper deals with neutron reasponse determination of different SSNTD-s made in the Institute of Physics in Belgrade and of the Kodak LR-115 (12 μm). Empirical formulas giving the relationship between the sensitivities of the SSNTD-s and neutron energy was proposed and used to determine the mean neutron sensitivities for different neutron fission spectra.

Neutron dose distribution measurements in a water filled phantom by SSNTDs x

ABSTRACT Kodak Pathe LR115 II type cellulose nitrate track detectors with different (n, ∞) radiators were calibrated in various isotropic neutron fields and used for neutron dose distribution measurements in a water filled elliptical phantom irradiated with neutrons from different light water moderated reactors.

One attempt to measure the threshold energy of alpha particle in Kodak CA 80–15 cellulose nitrate track detector

Abstract Experimental studies on track registration properties of alpha particle were performed in Kodak CA 80–15 cellulose nitrate SSTD (Solid State Track Detector). The α-particles were produced by a nuclear reaction 19F(p,α)16O. Energy spectrum of α-particles and the maximum registration range R reg were measured by means of track diameter kinetics. The threshold energy E c being equivalent to R reg in the cellulose nitrate SSTD was found to be 3.1 ± 0.4 MeV. Corresponding REL c (critical Restricted Energy Loss) was (1.0 ± 0.1) × 103 MeV.cm2/g. These values determined by our method are reasonable on account of other data developed with other methods by some researchers.

Long-range alpha-particle detection in a cellulose nitrate track detector

The rear-etching technique has been used to study the long-range alpha-particles emitted in 252Cf spontaneous fission. The energy spectrum and the probability of emission of these particles have been determined.

Enhancement in the energy resolution of cellulose nitrate track detectors for alpha particles

Different irradiation and etching modes have been investigated to improve the energy resolution properties of cellulose nitrate track detectors when used as alpha particle spectrometer. In this connection CA80-15 and LR-115 plastics were employed for the separation of alpha particle peaks from 239Pu and 238U sources. Enhancement in the energy resolution has been observed when the detectors are etched from the reverse side, or if some degrading foils of optimum thickness are interposed between the source and the detector surface to be analysed. In both the above mentioned modes of enhancement in energy resolution, the regions of maximum damage (the Bragg peaks) occuring along the particle trajectories are attacked immediately with the starting of the etching process. The peaks in the Bragg curve occur at different places when different energy alpha particles pass through the detector. Drastically different rates of energy losses at these places are responsible for the diametric separation of the damage trails.

Some basic studies on the absolute determination of radon concentration in the air by a cellulose nitrate track detector

Some basic studies were carried out on the Kodak LR 115 film for the determination of the 222Rn concentration in air using a cellulose nitrate track detector. The factor was obtained which converts the number of perforated tracks registered on a unit area of the detector film to the 222Rn concentration in a unit volume of air. Theoretical equations were derived for the special case of detecting only perforated etched tracks in a thin cellulose nitrate film. The experimental and the theoretical conversion factors are compared and discussed. The effective critical energy and the bulk etching rate were found to be 2.87 MeV and 0.046 μm min −1, respectively, when the film was etched for 160 min using 10% (w/v) NaOH solution at 60°C.

Low-energy cross sections for 6Li(d, α) 4He and 6Li(d, p) 7Li reactions

Cross sections were determined for the 6Li(d, α) 4He and 6Li(d, p) 7Li reactions between 100 and 180 keV deuteron energy by means of direct detection of α's and protons using cellulose nitrate track detectors. Different methods of extrapolation were employed and compared down to the energy region of astrophysical interest.

Effect of Gamma-Ray Irradiation, on Cellulose Nitrate Track Detector

The influence of γ-irradiation on the bulk etching rate of cellulose nitrate is described. The increase in bulk etching rate induced by γ-ray from 60Co has been measured at different irradiation doses and at different etching temperatures. From this temperature dependence the activation energy for the etching reaction is obtained. Some conclusions derived from experimental results are discussed in relation to a criterion for track registration.

Effect of gamma-ray irradiation on cellulose nitrate track detector.

The influence of γ-irradiation on the bulk etching rate of cellulose nitrate is described. The increase in bulk etching rate induced by γ-ray from 60Co has been measured at different irradiation doses and at different etching temperatures. From this temperature dependence the activation energy for the etching reaction is obtained. Some conclusions derived from experimental results are discussed in relation to a criterion for track registration.

The decay products of 222rn in etched track radon detection

Precipitation of decay products of atmospheric 222 Rn in small containers and the effects of their precipitation on alpha-particle-track-measurements of radon activities were studied. From decay curves of decay product activities on surfaces exposed to radon-containing air the ratios 214 Pb/ 218 Po (= r ) in the precipitates were determined. From r average ages of precipitating decay products were calculated. Average ages and r were low, indicating rapid precipitation of decay products, and decreased with container size. Activities on exposed surfaces were approximately those expected if decay products precipitate completely and uniformly on the internal surfaces of containers. Decay products precipitated on foils of correct thickness covering cellulose nitrate (CN) track detectors produce tracks. Therefore track densities produced by given radon activities are increased by such covers to extents predictable from the decay product activities on the overlays. Tracks formed under overlays may etch to larger, more vertical-sided, more easily counted forms. When suspended, uncovered, in air at distances from surfaces greater than the ranges of the alpha particles, three types of CN recorded tracks at the rate (ρ′) of 0.12 tracks cm −2 (pCi Rn) −1 1 −1 hr −1 as predicted by a theoretical expression. In small containers (ρ′) varied with position and container size.

Spark counting of α-radiograms recorded on LR-115 strippable cellulose nitrate film

In this paper a study on the spark counting of etch-holes of α-particle tracks recorded on 13 μm strippable cellulose nitrate track detectors (Kodak-Pathé LR-115 films) is described. Results for the counting characteristics as a function of etching and irradiation parameters are given. Applications of the spark counting technique to α-radiograms obtained by the ( p, α) nuclear reaction and soil-radon exhalation measurements are presented.

The development and use of solid-state nuclear track detectors (SSNTDs) for reactor physics experiments

Attempts have been made to develop solid-state nuclear track detectors (SSNTDs) for the measurement of (a) fast and thermal neutron fluences, and (b) high gamma doses existing around a reactor core and the spent fuel elements of Pakistan Research Reactor (PARR). Special attention has been paid to finding the registration efficiency of a CA80-15 cellulose nitrate track detector coated with lithium tetra borate for thermal and epi-thermal neutrons. Various plastics have been tested and calibrated for the measurement of high gamma doses in the reactor core itself. Also, these detectors have been used in the determination of thermal and epi-thermal neutron fluences and, after shutdown, gamma doses in the thermal column and the core of Pakistan Research Reactor (PARR). The results have been compared with those obtained by using other methods.

Status report: Direct track detector dosimetry in negative pion beams

Cellulose nitrate and Lexan polycarbonate track detectors have been exposed in a water phantom to 350 Rad in a stopping negative pion beam. The dose is measured at the “peak” or star region. The vertical beam from the Biomedical Channel at the Los Alamos Medium-Energy Physics Facility (LAMPF) was used. Heavy ions from negative pion interactions in the “peak” region and “plateau”, or entrance, region were determined by the step etch technique. The ions, and thus the linear energy transfer spectrum from pion interactions with oxygen, have been tentatively identified. The cellulose nitrate track detectors have also been used to measure superficial dose contours of the high LET portion of the peak pion beam in the first human biology trails. These results will be discussed.

Etch induction time in cellulose nitrate: A new particle identification parameter

By the use of a “continous etch” method, it has been ascertained that particle tracks do not appear in cellulose nitrate track detectors until a certain finite time after etch has been started: this etch induction time may provide a unique signal for distinguishing ions of different atomic number, Z, and possibly also resolving the mass, M, of such ions. Empirical relations between etch induction time and various experimental quantities are described, as is a simple theory of the cause of etch induction time, which can be related to experimental evidence on hand. There is reason to believe that etch induction time appears in other types of plastic track detectors and may indeed be a general phenomenon all track detectors.