Indoor Radon （^222Rn） Concentration Level Study in Child Care Centers and Kindergartens, Using Nuclear Track Methodology （NTM）

As it is known, staying for long periods of time in a place with high concentration of radon is a health hazard. This health risk can be increased into adulthood, if at infant ages the young people grow inside places with important indoor radon levels. Causal associations between exposure level and lung cancer have been demonstrated in epidemiological studies around the world, suggesting that for younger age children groups, the risk coefficient of lung cancer for inhaled radon and their daughters is about a factor of 4 on children from recent born to 10 years old, and 2 for ages between 10 to 20 years old. The aim of this work is to determine the indoor radon levels where infants, from 3 months to 6 years old, remain long times in child care centers and kindergartens. Indoor radon （222Rn） concentration levels were measured in the child care centers and kindergartens of the 16 political administrative regions, covering 5% of the total in Mexico City. This study was conducted over a one-year period, divided into four three-month periods coinciding with the seasons. Nuclear Track Methodology was selected for the measurements, and a passive close-end-cup-device was designed specifically to be used in children places. In this study, the results of measurements of indoor radon concentration in child care centers and kindergartens in Mexico City are encouraging, finding indoor radon levels between 26 Bq/m^3 and 75 Bq/m^3 with an average value of 51 Bq/m^3. It can be considered that the indoor radon concentration levels are low in this type of buildings, due to the benign climate in the city, the architecture design of the constructions, and the ventilation habits of the population.

Radon and Thoron （222Rn and 220Rn） Concentration Distribution Study on Three Detection Planes inside of a Closed Room Using Nuclear Track Methodology

The aim of this study is to determine the indoor radon and thoron concentration distribution on three detection planes, inside of a controlled closed room with microclimate conditions with NTM （Nuclear Track Methodology）, using CR-39 Lantrack bared detectors. One hundred sixty two （162） 1.9 cm × 0.9 cm CR-39 polycarbonate chips were placed in each one of the three planes, 2.0 m × 2.0 m square structures, distributed uniformly in 18 columns and 18 lines, in each plane. After three months exposure to indoor radon and thoron inside of the closed room, with a main concentration value of 862 ± 49 Bq/m3, all the detectors were chemically etched in KOH-6.25M solution to 60 ± 1 ℃ for 18 h, following the well established protocols for indoor radon survey, by the Dosimetry Applications Laboratory of the Physics Institute, UNAM （National Autonomous University of Mexico） and later on read by DIAS （Digital Image Analysis System）.The results show that the radon and thoron concentration distribution is not homogeneous in anyone of the planes faces. The six faces of the three planes measured, have a very particular distribution. From the results, it can be observed that each side of each plane shows a peculiar distribution, with gradients of concentrations higher than 50% from one area to another of the same measured plane. These results can help to understand the dynamics of the radioactive gases,and their measurements.

Measurement of Radon Gas Concentrations in Tap Water Samples for Thi-Qar Governorate Using Nuclear Track Detector (CR-39)

In the present work, we have measured the radon gas concentrations in tap water samples are taken directly from drinking tap water in sites houses being carried in Thi-Qar governorate by using nuclear track detector (CR-39). The results of measurements have shown that the highest average radon concentration in water samples is found in AL-Refai region which is equal to (0.223 ± 0.03 Bq/L), while the lowest average radon gas concentration is found in AL-Fajr region which is equal to (0.108 ± 0.01 Bq/L), with an average value of (0.175 ± 0.03 Bq/L). The highest value of annual effective dose (AED) in tap water samples is found in AL-Refai region, which is equal to (0.814 μSv/y), while the lowest value of (AED) is found in AL-Fajr region which is equal to (0.394 μSv/y), with an average value of (0.640 ± 0.1 μSv/y). The present results have shown that radon gas concentrations in tap water samples are less than the recommended international value (11.1 Bq/L). There for tap water in all the studied sites in Thi-Qar governorate is safe as for as radon concentration being concerned.

Measurement of cross sections for charge pickup by 84Kr on Al, C and CH2 targets at 400 MeV/u

The nuclear charge pickup cross sections of 84Kr on CH2,C,and Al targets are investigated using CR-39 nuclear track detector at the highest energy of 395 MeV/u.The cross sections for H are calculated from those measured on C and CH2 targets.The dependence of the charge pickup cross section on target mass is studied.

Neutron activation analysis of ceramic tiles and its component and radon exhalation rate

The concentrations of 20 trace elements in several ceramics tiles and ceramic composites used in Egypt were elementally analyzed by neutron activation analysis(NAA) technique. The samples and standard were irradiated with reactor for 4 h(in the Second Research Egyptian Reactor(Et-RR-2)) with thermal neutron flux 5.9×10 13 n/(cm 2·s).The gamma-ray spectra obtained were measured for several times by means of the hyper pure germanium detection system(HPGe). Also a solid state nuclear track detector(SSNTD) CR-39, was used to measure the emanation rate of radon for these samples. The radium concentrations were found to vary from 0.39—3.59 ppm and the emanation rates were found to vary from (0.728—5.688) × 10 -4 kg/(m 2· s).The elemental analysis of the ceramic tiles and ceramic composites have a great importance in assigning the physical properties and in turn the quality of the material.

A Review of Studies of Polymeric Membranes by Positron Annihilation Lifetime Spectroscopy

A review is presented of studies of polymeric membranes by applying positron annihilation lifetime spectroscopy （PALS）. PALS has been used to study subnanometer-sized holes, to determine their size distribution and free-volume fractions, and to probe molecular-sized vacancies in glassy polymers. At present, PALS is believed to be a highly effective physical method for the examination of polymeric membranes.

Indoor^(222)Rn Levels and Effective Dose Estimation of Academic Staff in izmir-Turkey

Objective To investigate the annual effective doses from indoor radon received by academic staff in the Faculty building. Methods Measurements of indoor radon concentrations were performed in the Arts and Sciences Faculty of Dokuz Eylul University for two surveys of about 1 month duration respectively using the SSNTD （Solid State Nuclear Track Detectors） method with LR115 detectors. Time integrated measurements comprised different locations inside the faculty building： classrooms, toilets, canteen and offices. Homes of academic staff were also tested for radon. Results The aritthmetic mean radon concentration is 161 Bq m-3 with a range between 40 and 335 Bq m-3 in the Faculty. Six offices and three classrooms have a radon concentration above 200 Bq m-3. The results show that the radon concentration in classrooms is generally higher than in offices. Based on the measured indoor radon data, the annual effective doses received by staff in the Faculty were estimated to range from 0.79 to 4.27 mSv, according to UNSCEAR methodology. The annual effective doses received by staff ranged from 0.78 to 4.20 mSv in homes. On average, the Faculty contributed 56% to the annual effective dose. Conclusion Reported values for radon concentrations and corresponding doses are within the ICRP recommended limits for workplaces.

Characteristics of Ions Emitted from Laser-Induced Silver Plasma

In this work, study of laser-induced ions is presented. The plasma was produced by focusing a Nd：YAG laser, with a wavelength of 1064 nm, a pulsed width of 9-14 ns, a power of 1.1 MW and energy of 10 mJ, on silver target in vacuum （10-3 Torr= 1.3332 Pa）. The characteristics of ion streams were investigated by CR-39 detectors located at angles of 0°, 30°, 60° and 90° with respect to normal of the target. The distance between the silver target and each detector was 11 cm. The energy of silver ions was found ranging from 1.5 eV to 1.06E4 eV. There was a high concentration of ions with low energy as compared to those with high energy, showing the energy distribution amongst the ions. The flux of ions was maximum in the axial direction which was decreasing with the angle increase with respect to normal of the target, and finally became minimum in the radial direction. Hence the silver ions have shown anisotropic behaviour.

α-emitters Concentration in Urine Using Natural Exposure Technique

The CN-85 nuclear track detector has been implemented for determining uranium concentration in human urine sample for different radiation workers in different Iraqi government, hospitals （nuclear medicine unit worker, X-ray and MST worker {the ministry of science and technology}）, for different ages,gender and working years.The exposure method was used by immersing CN-85 detectors in urine samples for four weeks, then CN-track detectors were etched by 6.25 N NaOH for 90 mints. The alpha emitter＇s concentrations for urine samples were calculated in comparison with standard samples. The results show that the average of uranium concentration for nuclear medicine 1.2725 ppb, 1.1896 ppb for X-ray workers, 1.3858 ppb for MST, 1.412 for CTS worker, and 0.848 ppb for control peoples. The average uranium concentration for nuclear medicine, X-ray, MST, and CTS （meal only） workers was 1.277 ppb, 1.1969 ppb, 1.3858 ppb and 1.463 ppb. While 1.25 ppb, 1.158 ppb, 1.385 ppb, and 1.293 ppb for female respectively, while for control people was 0.849 ppb for meal and 0.846 ppb for female. The results of this work regarding the dependence of concentrations on the person＇s occupation, years of service, sex and age.

DETERMINATION OF RADON AND NATURAL RADIOACTIVITY CONCENTRATION IN SOME BUILDING MATERIALS USED IN IZMIR,TURKEY

The aim of this study is to determine the radon and natural radioactivity concentra-tions of some building materials and to assess the radiation hazard associated with those mortar materials when they are used in the construction of dwellings.Radon measurements were realized by using LR-115 Type 2 solid state nuclear track detec-tors.Radon activity concentrations of these materials were found to vary between 130.00±11.40 and 1604.06±40.5 Bq m^(-3).The natural radioactivity in selected mortar materials was analyzed by using scintillation gamma spectroscopy.The activity concentrations for 226Ra,232Th and 40K for the studied mortar materials ranged from ND to 48.5±7.0 Bq kg^(-1),ND to 41.0±6.4 Bq kg^(-1)and ND to 720.4±26.8 Bq kg^(-1),respectively.Radium equivalent activities,external and internal hazard indexes,gamma and alpha indexes and absorbed gamma dose rates were calculated to assess the radiation hazard of the natural radioactivity in studied samples.The calculated Raeq values of all samples were found to be lower than the limit of 370 Bq kg-1 set for building materials.The estimated hazard index values were found to be under the unity and the absorbed dose rate values were also below the worldwide average of 84 nGy h^(-1).

Research Program of Determination of Geological Age by Thermal Analysis Method

On the basis of previous research achievements of measuring the solid state nuclear track in apatite by thermal analysis method, the author further proposes the research program to measure the energy deposited by the solid state nuclear track contained in zircon, sphene, epidote, apatite and other samples, in order to study the geological age and geothermal history. Compared with the measurement of nuclear track density by etching method, this one does not need to conduct so many processing programs for samples, but can improve the measurement accuracy.