Fission Fragment Tracks Research Articles

Working properties of GEM-TPC at low pressure

Despite the fact that nuclear technology has already been widely used in the energy sector, the research in this regard have been kept on worldwide. The precise detection of fission fragment tracks is still a knotty issue due to the limits of traditional measurement methods. The inventions of the Gas Electron Multiplier (GEM) as well as its combination with Time Projection Chamber (TPC) detection technology have made many breakthroughs in the multi-parameter correlation measurement of fission fragments tracks. Based on this technology, we designed and built a GEM-TPC detector. To acquire more accurate spatial and energy information, extending the fission fragment tracks by reducing the air pressure in the detector might be an ideal option. At present, since the research on GEM detectors working at low pressure is relatively rare, emphasis in the paper has been put on discussing the working characteristics of our detector in this pressure region in detail. It can be concluded that the lower the working gas pressure, the lower the GEM voltage required to obtain the same gain. In other words, the working voltage range of GEM-TPC will move to a lower level, and the energy resolution of GEM-TPC will first become better and then become worse rapidly as the working gas pressure continues to decrease.

A Study of The Radionuclides of The Petroleum Waste In Dora and Bijie Refineries Using (Hpge) Detector

The aim of this study is to detect the radioactivity of radionuclides and measure the specific activities and the uranium concentration in (19) samples of crude oil and oil waste were brought from two oil locations Dora refinery, Bijie refinery.
 The measurements in this study were done by using two techniques:
 1- Gamma rays spectroscopy system was used to measure the specific activity for radionuclides. This system is consist of high purity of germanium detector (HPGe) with personal computer as multi channel analyzer (MCA) that computerized to plot the radioactive spectrum and compute the specific activities of the radionuclides. There are seven radionuclides are detected:
 (Bi-214, Ra-226, TI-208, Bi-212, Pb-212, K-40, and Cs-137), these radionuclides included; two
 
 radionuclides (Bi-214,Ra-226) belong to the U-238 series, three radionuclides (TI-208, Bi-212, Pb-212) belong to Th-232series, one natural radionuclide (K-40), and one artificial radionuclide (Cs-137).
 For Dora refinery samples, the averages of specific activities of (Bi-214, Ra-226) were (7.79, 16.08) Bq/kg respectively, the averages of specific activities of (TI-208, Bi-212, Pb-212) were (7.95,4.05,5.75) Bq/kg , the average of specific activities of (Cs-137) was (0.64) Bq/kg , the average of specific activities of (K-40) was (99.3) Bq/kg.
 For Bijie refinery samples, the average of specific activities of (Bi-214) was (0.39) Bq/kg, the averages specific activities of (Bi-212, Pb-212) were (0.02,0.01) Bq/kg, the average of specific activities of (K-40) was (2.28) Bq/kg , and three radionuclides (Ra-226, TI-208, and Cs-137) were not appeared in Bijie samples.
 2- solid state nuclear track detectors technique (SSNTDs), the uranium concentration determined by using CR-39 track detector and fission fragment track technique, the nuclear reaction used as source of uranium fission fragment is U-235 (n-f) obtained by the bombardment of U-235with thermal neutrons emitted from (Am-Be) neutron source with flux (5000 n/cm2.s) for seven days, the concentration were calculated by
 comparison with the standard samples. The uranium concentration in Dora refinery samples were ranged between (0.95-3.34) ppm with average (2.03) ppm for solid samples and (1.25) ppm for liquid samples. The uranium concentration in Bijie refinery samples were ranged from (0.42-1.46) ppm with average (0.55) ppm in the solid samples and (1.24) ppm in the liquid samples, these results are agreement with the permissible limit from IAEA, the permissible limit is (1mSv/y) for the public.

Addendum to “Annealing of fission fragment tracks in CR-39 nuclear track detector — Phenomenological model” [Nucl. Instrum. Methods A 940 (2019) 40–44

Addendum to “Annealing of fission fragment tracks in CR-39 nuclear track detector — Phenomenological model” [Nucl. Instrum. Methods A 940 (2019) 40–44

Neutron-induced fission fragment angular distributions, anisotropy, and linear momentum transfer measured with the NIFFTE fission time projection chamber

The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has performed measurements with a fission time projection chamber (fissionTPC) to study the fission process by reconstructing full three-dimensional tracks of fission fragments and other ionizing radiation. The amount of linear momentum imparted to the fissioning nucleus by the incident neutron can be inferred by measuring the opening angle between the fission fragments. Using this measured linear momentum, fission fragment angular distributions can be converted to the center-of-mass frame for anisotropy measurements. Angular anisotropy is an important experimental observable for understanding the quantum mechanical state of the fissioning nucleus and vital to determining detection efficiency for cross section measurements. Neutron linear momentum transfer to fissioning $^{235}$U, $^{238}$U, and $^{239}$Pu and fission fragment angular anisotropy of $^{235}$U and $^{238}$U as a function of neutron energies in the range 130 keV--250 MeV are presented.

Summary of a comprehensive data bank for nuclear track research using CR-39 detectors

This data bank is the result of systematic experiments on nuclear track etching, fission fragment track annealing, and radiation detection & measurement. Data highlights from a comprehensive nuclear track data bank, and related physics and chemistry are described here briefly and clearly. Uncertainties in the reported data are also presented. All the data presented were collected using the most sensitive nuclear track detector CR-39, or Poly Allyl Diglycol Carbonate (PADC), over two decades. Closely related data sets from the published literature are also reviewed. Necessary details of the reviewed data and their citations are clearly given in the data bank. Aim here is to present tabulated experimental raw data with essentially needed calculations. All the necessary information related to the data bank is described clearly. Study presented here is useful for research students and scientists who possess the rudimentary knowledge of nuclear track detection. Single tabulation of the data, instead of plots, is aimed at making easy access of the data to users.

Annealing of fission fragment tracks in CR-39 nuclear track detector — Phenomenological model

Abstract In this short paper, a new model for annealing of latent nuclear tracks is developed. Physical phenomenological picture or foundation of the model is presented using experimental spectra of 252Cf fission fragment tracks annealed at 75–175 °C for 5–30 min. Here, annealing of nuclear tracks refers to the reduction of track lengths during annealing or thermal treatment. A new annealing parameter (t/T2) is identified in the model, which is useful in understanding and analysis of annealing of nuclear tracks. In definition of the annealing parameter above, the quantities t and T are annealing time and temperature, respectively. The model allows deduction of the activation energy of annealing simultaneously from track annealing data, collected over all the annealing conditions (t, T). This model provides a quick methodology to study kinetics of nuclear track annealing. The presented model is validated using the experimental results of annealing of fission tracks in CR-39 detector. The determined value of activation energy of annealing is 0.204 ± 0.012 eV. Presented results and discussion can be extended to swift heavy ion (SHI) tracks.

Measurement of radon and uranium concentration in soil samples from Babylon cement plant using nuclear track detector CR-39

In this study, concentrations of radon and uranium were measured for twenty six samples of soil. The radon concentrations in soil samples measured by registrant alpha-emitting radon (222Rn) by using CR-39 track detector. The uranium concentrations in soil samples measured by using registrar fission fragments tracks in CR-39 track detector that caused by the bombardment of U with thermal neutrons from 241 Am-Be neutron source that has flux of 5 ×103n cm-2 s-1.The concentrations values were calculated by a comparison with standard samples The results show that the radon concentrations are between (91.931-30.645Bq/m3).The results show that also the uranium concentrations are in soil samples under 0.051-0.0079ppm.

Determination the Uranium Concentration in Some Plants and Soils From Baghdad Using CN-85 Track Detector

The aim of this study is to measure the concentrations of uranium for (17) samples of plants and soils that collected from different areas in Baghdad city. The technique is based on the calculation of the probability of registration α–particles by using the CN-85 track detector that is one of solid state nuclear track detectors SSNTDs and fission fragment track technique. The nuclear reaction used as source of uranium fission fragment is U-235 (n-f) obtained by the bombardment of U-235 with thermal neutrons emitted from (Am-Be) neutron source with thermal neutron flux (5000n/cm2.s) for seven days. The concentration of uranium was calculated by comparison with the standard samples. The concentrations of uranium in plants samples was ranging between (0.8-2.37 ppm) with average of (1.59 ppm). The concentrations of uranium in soils samples was ranging between (3.67-3.99ppm) with average of (3.82ppm). All results are agreement with the permissible limit and less than the allowed limit (11.7 ppm) from UNSCEAR.

Thermodynamics of nuclear track chemical etching

This is a brief paper with new and useful scientific information on nuclear track chemical etching. Nuclear track etching is described here by using basic concepts of thermodynamics. Enthalpy, entropy and free energy parameters are considered for the nuclear track etching. The free energy of etching is determined using etching experiments of fission fragment tracks in CR-39. Relationship between the free energy and the etching temperature is explored and is found to be approximately linear. The above relationship is discussed. A simple enthalpy–entropy model of chemical etching is presented. Experimental and computational results presented here are of fundamental interest in nuclear track detection methodology.

Ultraviolet radiation-induced modifications of the optical and registration properties of a CR-39 nuclear track detector

The UV–VIS (ultraviolet–visible) spectra and etching characteristics of poly allyl diglycol carbonate (PADC, a form of the CR-39 polymer) detector films after exposure to UV radiation for various times have been studied. Etching experiments were carried out on the UV-exposed CR-39 detectors after alpha particle and fission-fragment irradiation using a 252Cf source. The bulk and track etch rates were measured using the alpha and fission-fragment track diameters, and the sensitivity and the detection efficiency were also determined. The optical band gap for both indirect and direct transitions was calculated based on the absorption edge of the UV spectra of the pristine and variously UV-exposed detectors. The optical band gap evidently indicates a gradual change in the optical properties of the CR-39 detector that is induced by the UV radiation. This study shows that the UV-exposed CR-39 detectors were demonstrated to be highly sensitive to alpha particles, but proved to be somewhat less sensitive to the fission fragments.

Measurements of nuclear track etch induction time in Markrofol for alpha particles from a 252-Cf source

Makrofol DE1-4C detectors were exposed to fission fragments and alpha particles (of energy 0.5–3 MeV) from a 252Cf source in a vacuum chamber. The exposed detectors were etched in 6-N NaOH solution at 70 °C to measure etch induction times. An optical microscope was used to investigate various charged particle tracks and diameters in Makrofol detectors. The etch induction times for alpha-particle and fission-fragment tracks were obtained from the intersections of extrapolations of a graph of track diameters with time. The obtained results will be very useful in nuclear track studies, as well as nanotechnology fields.

Thin extractive membrane for monitoring actinides in aqueous streams

Alpha spectrometry and solid state nuclear track detectors (SSNTDs) are used for monitoring ultra-trace amount of alpha emitting actinides in different aqueous streams. However, these techniques have limitations i.e. alpha spectrometry requires a preconcentration step and SSNTDs are not chemically selective. Therefore, a thin polymer inclusion membrane (PIM) supported on silanized glass was developed for preconcentraion and determination of ultra-trace concentration of actinides by α-spectrometry and SSNTDs. PIMs were formed by spin coating on hydrophobic glass slide or solvent casting to form thin and self-supported membranes, respectively. Sorption experiments indicated that uptakes of actinides in the PIM were highly dependent on acidity of solution i.e. Am(III) sorbed up to 0.1molL−1 HNO3, U(VI) up to 0.5molL−1 HNO3 and Pu(IV) from HNO3 concentration as high as 4molL−1 . A scheme was developed for selective sorption of target actinide in the PIM by adjusting acidity and oxidation state of actinide. The actinides sorbed in PIMs were quantified by alpha spectrometry and SSNTDs. For SSNTDs, neutron induced fission-fragment tracks and α-particle tracks were registered in Garware polyester and CR-39 for quantifications of natural uranium and α-emitting actinides (241Am/239Pu/233U), respectively. Finally, the membranes were tested to quantify Pu in 4molL−1 HNO3 solutions and synthetic urine samples.

Modifications of the registration properties of charged particles in a CR-39 polymeric track detector induced by thermal annealing

The thermal annealing behavior of alpha and fission fragment tracks, following exposure pre- and post-annealing, in a high polymer material of poly allyl diglycol carbonate (PADC), a form of CR-39, has been investigated as a function of temperature and time. Isothermal and isochronal annealing experiments were carried out on CR-39 polymeric detectors exposed to a 252Cf source. The yields of fission fragment and surviving alpha tracks were measured as a function of annealing time and temperature, as was the variation of fission track diameter with annealing time. The bulk and track etch rates were measured using alpha and fission fragment track diameters and the bulk etch rate was also measured by the weight loss method. The activation energy of annealing was determined using two different models based on the experimental results. This paper presents novel information showing that the annealed CR-39 detectors were demonstrated to be highly sensitive to the fission fragments, but not to alpha particles.

Fission studies of gold induced by (1665 MeV) π− using a CR-39 detector

The fission cross section and fission probability of 197Au, induced by (1665 MeV) π−, have been studied using CR-39 track detectors. A 4π-geometry was used to count track statistics. A beam of negative pions of 1665 MeV was produced at AGS of Brookhaven National Laboratory, USA, and allowed to fall normally on the stack. Two detectors from the stack were scanned for fission fragment tracks after etching in 6N NaOH at 70 °C. The statistics of fission fragment tracks in both detectors were obtained. It was found that there was a marked asymmetry of registered tracks with respect to the forward and backward hemispheres. This asymmetry could be partly accounted for on the basis of momentum transfer to the struck nucleus. On the basis of counting statistics fission cross section was measured, and fission probability was determined by dividing the fission cross section with the reaction cross section. The fission cross-section and fission probability were compared with the computed values using the cascade-exciton model code CEM95.

Mechanisms and kinetics of nuclear track etching and annealing: Free energy analysis of damage in fission fragment tracks

Mechanisms and kinetics of etching and annealing of fission fragment tracks in CR-39 have been investigated. Kinetics of bulk etching and that of fission fragment track etching in CR-39 are described in a systematic manner. Activation energies of etching and annealing were determined from the experimental results through Arrhenius type, t=toexp(Ea/kBT), empirical relationships and models. The increase of free energy in fission fragment track formation in CR-39 is also determined from the measurements of track parameters. Activation barriers of bulk etching, track etching and track annealing in CR-39 are compared and discussed. This paper presents an anatomy of fission fragment tracks. Analyses of experimental results and comparison of above mentioned energies have yielded the important physics information usable in nuclear track methodologies, including nuclear geophysics and geochemistry, and radiation damage in solids.

Swelling and structure of radiation induced near-surface damage in CR-39 and its chemical etching

Abstract Systematic measurements of swelling of CR-39 nuclear track detector (NTD) due to irradiation with fission fragments and alpha particles over a wide range of fluences from 252Cf are presented here. Precisely designed and optimized exposure and chemical etching experiments were employed to unfold the structure of radiation induced surface damage. Delays in the startup of the chemical etching of latent tracks in low radiation fluence detectors are measured and are found to contain important information about structure of the surface damage. Simple atomic scale pictures of radiation induced surface damage and its chemical etching are developed using measurements of radiation induced swelling of CR-39 detectors and nuclear track parameters. The computer code SRIM2010 was utilized for the calculations of basic features of latent tracks of fission fragments and alpha particles in CR-39. Another computer code TRACK_VISION was used to compute parameters of etched tracks. Computations and experimental findings in the paper coherently compose a realistic picture of radiation damage.

PION-INDUCED FISSION OF 209Bi AND 119Sn: MEASUREMENTS, CALCULATIONS, ANALYSES AND COMPARISON

Cross-sections for the π--induced fission of 209 Bi and 119 Sn have been measured using the most sensitive CR-39 solid-state nuclear track detector. In experiments, target–detector stacks were exposed to negative pions of energy 500, 672, 1068, and 1665 MeV at the Brookhaven National Laboratory, USA. An important aspect of the present paper is the comparison of pion-induced fission fragment spectra of above mentioned nuclei with the spontaneous fission fragment spectra of 252 Cf . This comparison is made in terms of fission fragment track lengths in the CR-39 detectors. Measurement results are compared with calculations of Monte Carlo and statistical weight functions methods using the computer code CEM95. Agreement between measurements and calculations is fairly good for 209 Bi target nuclei whereas it is indigent for the case of 119 Sn . The possibilities of the trustworthy calculations, using the computer code CEM95, comparable with measurements of pion-induced fission in intermediate and heavy nuclei are explored by employing various systematics available in the code. Energy dependence of pion-induced fission in 119 Sn and 209 Bi is analyzed employing a newly defined parameter geometric-size-normalized fission cross-section [Formula: see text]. It is found that the collective nuclear excitations, which may lead to fission, become more probable for both 209 Bi and 119 Sn nuclei with increasing energy of negative pions from 500 to 1665 MeV .

Negative Pion Induced Fission with Heavy Target Nuclei

We investigate fission induced by negative pions in copper and bismuth targets using CR-39 dielectric track detectors. The target-detector assemblies in 4π-geometric configuration were exposed at the AGS facility of Brookhaven National Laboratory, USA. The exposed detectors were chemically etched under appropriate etching conditions and scanned to collect data in the form of fission fragments tracks produced as a result of interaction of pions with the target nuclei. Using the track counts, the experimental fission cross sections for copper and bismuth have been measured at energies of 500, 672, 1068 and 1665 MeV and compared with the calculation using the Cascade-Exciton Model code (CEM95). The values of fission probability based on experimental fission cross-sections have been compared with the theoretically calculated values of fission probabilities obtained using the CEM95 code. Good agreement is observed between the measured and computed results.

QUANTITATIVE PLUTONIUM MICRODISTRIBUTION IN BONE TISSUE OF VERTEBRA FROM A MAYAK WORKER

The purpose of this study was to obtain quantitative data on plutonium microdistribution in different structural elements of human bone tissue for local dose assessment and dosimetric models validation. A sample of the thoracic vertebra was obtained from a former Mayak worker with a rather high plutonium burden. Additional information was obtained on occupational and exposure history, medical history, and measured plutonium content in organs. Plutonium was detected in bone sections from its fission tracks in polycarbonate film using neutron-induced autoradiography. Quantitative analysis of randomly selected microscopic fields on one of the autoradiographs was performed. Data included fission fragment tracks in different bone tissue and surface areas. Quantitative information on plutonium microdistribution in human bone tissue was obtained for the first time. From these data, the quantitative relationships of plutonium decays in bone volume to decays on bone surface in cortical and trabecular fractions were defined as 2.0 and 0.4, correspondingly. The measured quantitative relationship of decays in bone volume to decays on bone surface does not coincide with recommended models for the cortical bone fraction by the International Commission on Radiological Protection. Biokinetic model parameters of extrapulmonary compartments might need to be adjusted after expansion of the data set on quantitative plutonium microdistribution in other bone types in humans as well as other cases with different exposure patterns and types of plutonium.

Systematic measurements of etch induction time for nuclear tracks: Startup of etching and the multiplex effect

Systematically planned new experiments were performed on fission fragment and alpha particle tracks in CR-39. In the present experiments, special attention was paid to reduction of spurious variations and fluctuations during exposures, chemical etching and etched track measurements. Measurements of etch induction time ( t ei ) for fission fragment and alpha particle (of energy 4.59–6.11 MeV) tracks were carried out. Potential of t ei for alpha particle spectrometry with CR-39 detector is demonstrated. Published results of atomic force microscopy (AFM) and conductometric cell measurements of various charged particle tracks in CR-39 and similar polymers were used as a support of the present results to propose a multiplex mechanism of startup of chemical etching of charged particle tracks. Results are useful for further development in the field of nuclear tracks and technology applications including nanotechnology.