Reactions of 15 MeV/n 238U on Ag have been studied by means of CR 39 detector. Analysis of 3 pronged events was done and classified as a function of impact parameter. For 4 and 5 pronged events, two and three steps mechanisms were found.
Plastic track detectors, viz. CR-39 and Lexan polycarbonate were irradiated at GSI, UNILAC using 208Pb(13.6 MeV/u), 238U(15 MeV/u), 132Xe(5.6 and 14.5 MeV/u) and 139La(14.6 MeV/u) beams. The experimental ranges of heavy ions are in good agreement with the theoretical ranges computed by using the computer programme based on equations of Mukherji and Nayak. Critical angle etching efficiency and REL values for plastic detectors are determined from their bulk and track etch rates. REL for Lexan polycarbonate is found to be 4.25 MeV mg-1 cm-2 . The efficacy of ‘Single Sheet Identification’ technique for low energy cosmic ray particles is established.
Passive radon measurement method was employed in order to determine radon activity concentrations in dwellings (mostly guest-houses) around the hot springs in the north west of Iran. The measurements were carried out during winter for a period of 2.5 months. Our results show that the radon levels in majority of dwellings have been higher than 100Bq/m3 and in two cases exceeded the limitation value recommended by ICRP for future homes (i.e 200Bq/m3). It is important to mention here that during the course of this measurement there happened an earthquake in the region which may have had some effect on the results.
The, track annealing phenomenon, which occurs in a heated mineral containing uranium like apatite, is analysed using the transmitted electron microscopy (TEM) associated to the platinium shadowed carbon replica method. The diameters of 86Kr (1,66 MeV/nucleon) ion tracks induced normally to the observation plane are measured during an etching stage with a very low concentrated etchant (HNO3 1%). The distribution of track diameters in a sample, and its variation following the annealing amount the apatite knew, lead us to agree with the track registration model which let appear more than one microscopic defect structure (Dartyge et al., 1981). This model cannot be observed with only unannealed etched tracks, but is clearly highlighted by the thermal annealing of nuclear tracks in this mineral.The opening track profile is analysed as a determination of the etching speed variation versus the distance to the ion trajectory. The variation is shown to be dependent on the cristallogaphy of the apatite. The different etching speeds, relative to the orientation with the c-axis of the apatite, influence the track shape for long etching times. The etched pit figure is not symetrical, and present in the c-axis direction a much more width opening than the etched track diameter. Finaly, the lateral track shape and the etched pit are supposed to be sensitive to the etchant strength.
Radon isotopes are practically inert and have properties of gases under conditions of geological interest. During their brief lives, their atoms are capable of moving from the sites of their generation. Radon diffusion studies were carried out in air, gravel, sand, soil and water using silicon diffused junction electronic detector. Alphameter-400. Diffusion constant and diffusion length is calculated for all these materials.
A scintillation detector of high energy radiation has been made based on the structure Bi4Ge3O12/ZnSexTe1-x/ZnSe. The heterostructure ZnSexTe1-x/ZnSe was used for efficient transformation of the wide luminescence spectrum of the substrate (Bi4Ge3O12 single crystal) into an electrical signal. Thin layers of ZnSexTe1-x and ZnSe have been grown in a vapour phase epitaxy (VPE) system using vaporization of ZnSe and ZnTe powder with a hydrogen carrier gas flow.
The detailed investigations of annealing behavior of fission fragment tracks in muscovite mica, apatite and whitlocite crystals have been performed. For muscovite mica the annealing procedure has been applied to single fission fragment tracks, for apatite and whitlocite crystals — for binary events. As it has been observed, the controlled annealing produced the shortening down of fission fragment track length. Such procedure provides more direct comparison of the track length spectra due to spontaneous fission of 238U and due to thermal neutron induced fission of 235U in the same crystal; it allows one to obtain more correct value of the track age.
The proton response of the TS-16 type of CR-39 plastic nuclear track detector has been studied with accelerated and fast neutron induced protons in vacuum and in air. The diameters of etched tracks were measured as a function of etching time and the etch rate ratio and the etch induction layer were determined from the growth curve of the diameter using a variable etch rate ratio model. In the case of the accelerated protons in vacuum an anomalous incident angle dependence of the response is observed.
Nine pelagic ferromanganese nodules from the South-Eastern Pacific have been analyzed by the alpha-radiography technique using the nitrate cellulose detector LR-115 (type 1). The obtained distributions of the total alpha-radioactivity characterize the growth processes in the recent time. The surface rinds of the nodules accumulated at 1–16 mm/Ma, a value which is in the normal range for deep-sea nodules from this region. Some nodules have been analyzed along two different radial directions which have rather different rates of accretion.
The fission track age and uranium content of various rocks such as Apatite, Sphene, Obsidian , Calcite and Fluorite from different region of the country has been determined. The apparent age was corrected by measurements of track lengths of fossil and induced fission tracks in the sample.
In this paper we will describe a new nuclear emulsion:technique, a digital controlled method, for making fast and accurate measurement and three-dimensional reconstruction of charged particle tracks in a special nuclear emulsion chamber, which is used as detector with target foil of silver, gold or lead nuclei by the CERN/EMU01 experiment and has the best resolution in the investigation of very high multiplicity in ultra-relativistic heavy ion collisions.
A new nuclear track detector, called SR-90, has been compared with two types of CR-39 nuclear track detectors (i) super grade PM-355 Pershore Mouldings/U.K. and (ii) MA-ND/α/Hungary. All types were irradiated with alpha and fission fragments and all etched under the same etching conditions. The bulk etching rate (Vb) of SR-90 was twice that of the CR-39 for all etching times. The track etching rate (Vt) of SR-90 starts with 8.5 μm.h-1 at 2 h etching time and increased to 13 μm.h-1 at 6.5 h, while for CR-39 remains nearly constant (2 μm.h-1) for all etching time. Thus, the sensitivity of SR-90 was found to improve with etching time. The surface of SR-90 is found to be rough and less transparent than both types of CR-39 detectors. The shape of perpendicular alpha and fission fragment tracks in SR-90 was not a uniform circular shape as in the CR-39.
The uranium contents of beverages and mineral water have been estimated using the technique of fission track analysis with polycarbonate detector. The U contents in beverages have been found to vary from 0.26 ± 0.03 to 1.65 ± 0.07 ppb, the average value is 0.93 ± 0.05 ppb. The mean U content in mineral water is 9.20 ± 0.16 ppb, which is ∼ 10 times higher than the mean U content of beverages. The present study shows the high U content in mineral water, indicating need for further investigation of U content in mineral water for the studies of radiation health hazards.
For more information about the sensitivity (exactly determination of the particle range and angles iun the stars) we have syntetized nuclear emulsion with ultra fine microcrystals AgBr (grains diameter under 0.10 microm). They are capable of registering ionizing particles of all energies. The goal were achieved by different physical and chemical conditions during making the sensitivity and the latent image centers and their new distribution on the surface of the AgBr microcrystals.
The light fragment emission from 3.65 A GeV 12C+208Pb reaction was investigated by using CR-39 plastic track detector. It was observed that the light fragments can be produced by the two different mechanisms.
This paper reports the measured results of radon concentrations at different positions of a house with CSR solid track detector with and without electret. The results show that the radon concentration is different at different positions of even the same room,it is the highest at end of a bed close to the wall, where his/her head usually is when the resident is on bed,being 1.6-1. 8 times that at the position 0. 5 m below the ceiling,and that at the middle of the room the radon concentration is decreasing with increasing height from the floor,the radon concentration at the height of 0. 88 m is about 1. 3- 1. 5 times that of 2. 4 m (0. 5 m below the ceiling).Based on the investigation,the radiation dose to the residents estimated in accordance with the average measured radon concentration at the location 0. 5 m below the ceiling should be multiplied by a correction factor of about 1. 5 to obtain the realistic dose.
The pressure applied to the electrochemical etching (ECE) chamber system and in turn to the rubber washers holding a detector tight in place was discovered to be a new parameter in ECE having a direct effect on internal heating and thus on the detector's response. The type, material, shape and size of the washers showed significant effects on the detector's response. Special pressure ECE (PECE) chambers with measurable and reproducible pressure were designed, constructed and used in this study. The effects observed seem to be due to forced vibrations of the detector in an electric field the degree of which depends on the pressure applied and stretching the detector, like winding the strings of a musical instrument. The results of the above studies are presented and discussed.
The heavy ion reaction of 14.2 MeV / N 238U + natU has been studied using muscovite detector and 2π—geometry detection technique. The reaction cross section and the partial cross sections of 3,4 and 5 massive fragments (each not less than 30u) exit channels have been obtained. The masses and energies of the fragments have been calculated according to the spherical coordinates of the tracks formed by the multifragments using the quantitative analysing methodology developed by P.A.Gottschalk et al. and the standard velocity—range data. Then the kinematical analysis on each selected event has been performed and it shows that the main reaction channel of 14.2 Mev / N U+U is the sequential fission of projectile-like or/and target-like nuclei resulting from inelastic or deep inelastic collision. Some features of the sequential fission have been drawn.
A new approach to dating zircon by combining fission and alpha tracks is described. In this method (alpha track method), spontaneous fission tracks in a sample are counted routinely and alpha tracks originating from the sample are counted on a plastic track detector. Uranium content of the sample is monitored based on the alpha track density and the detection time. Radioactive equilibrium and equal Th/U ratios among samples are assumed. A comparison between the conventional fission track method and the alpha track method has been made using age standard and other zircon samples. The results suggest that the alpha track method provides acceptable dating results when internal zircon surfaces are used for track counts. The alpha track method should be beneficial to those who do not have close access to neutron irradiation facilities.
