Ionizing and non-ionizing radiation and the risk of childhood cancer-illustrated with domestic radon and radio frequency electromagnetic field exposure

OpenAIRE

Hauri, Dimitri

2013-01-01

Background Children are exposed to many different environmental factors, including exposure to low-dose ionizing radiation and to non-ionizing radiation. Low-dose ionizing radiation comprises anthropogenic modified radiation and natural ionizing radiation from cosmic rays from the atmosphere, terrestrial gamma radiation from radionuclides in rocks and soils and radiation from radon. Non-ionizing radiation comprises optical radiation and radiation from electromagnetic fields. The la...

Ionizing energy in food processing and pest control. 1. Wholesomeness of food treated with ionizing energy

International Nuclear Information System (INIS)

Wierbicki, Eugen

1986-01-01

Congressional concerns about the use of ionizing energy for food preservation and to control pests in food products for export and domestic use promoted the preparation of this report by a special task force of the Council for Agricultural Science and Technology (CAST). An overview surveys research conducted on the toxicological safety, nutritional quality, and microbiological safety of foods treated with ionizing energy. Background information is provided on various types of electromagnetic radiation, effects of ionizing energy level and dose, sources of natural background radiation and induced radioactivity, and the nature and safety of various radiolytic products. Objectives, methodologies, and problems associated with feeding studies of toxicological safety are outlined; results of scientific studies, U.S. government wholesomeness studies, and international feeding studies are summarized. Studies on the nutritional value of food products processed using ionized energy have examined the effects of ionizing energy on 1) composite diets, 2) carbohydrates, 3) fats, 4) proteins and amino acids, 5) vitamins (potatoes, onions, fruits, meat, seafood, cereals, vegetables, dairy products, oils), 6) antivitamins, and 7) minerals. The report concludes that currently available scientific evidence indicates that foods exposed to ionizing energy under the conditions proposed for commercial application are 1) wholesome (safe to eat) and 2) comparable in nutritional adequacy to fresh or conventionally processed foods

Natural ionizing radiation and human health in Serbia

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Obradović-Arsić Danijela R.

2010-01-01

Full Text Available This paper provides information about potential effects of natural ionizing radiation on general population health. Natural radionuclides are particularly stressed, as well as health effects of high and lower doses. Radio-ecological areals have been presented for Serbia, while radiation risk has been assessed for the population of Serbia according to census years.

Transcriptome analysis reveals a stress response of Shewanella oneidensis deprived of background levels of ionizing radiation

Science.gov (United States)

Li, Xiaoping; Schilkey, Faye; Smith, Geoffrey B.

2018-01-01

Natural ionizing background radiation has exerted a constant pressure on organisms since the first forms of life appeared on Earth, so that cells have developed molecular mechanisms to avoid or repair damages caused directly by radiation or indirectly by radiation-induced reactive oxygen species (ROS). In the present study, we investigated the transcriptional effect of depriving Shewanella oneidensis cultures of background levels of radiation by growing the cells in a mine 655 m underground, thus reducing the dose rate from 72.1 to 0.9 nGy h-1 from control to treatment, respectively. RNASeq transcriptome analysis showed the differential expression of 4.6 and 7.6% of the S. oneidensis genome during early- and late-exponential phases of growth, respectively. The greatest change observed in the treatment was the downregulation of ribosomal proteins (21% of all annotated ribosomal protein genes during early- and 14% during late-exponential) and tRNA genes (14% of all annotated tRNA genes in early-exponential), indicating a marked decrease in protein translation. Other significant changes were the upregulation of membrane transporters, implying an increase in the traffic of substrates across the cell membrane, as well as the up and downregulation of genes related to respiration, which could be interpreted as a response to insufficient oxidants in the cells. In other reports, there is evidence in multiple species that some ROS not just lead to oxidative stress, but act as signaling molecules to control cellular metabolism at the transcriptional level. Consistent with these reports, several genes involved in the metabolism of carbon and biosynthesis of amino acids were also regulated, lending support to the idea of a wide metabolic response. Our results indicate that S. oneidensis is sensitive to the withdrawal of background levels of ionizing radiation and suggest that a transcriptional response is required to maintain homeostasis and retain normal growth. PMID:29768440

Modern state of the application of ionizing radiation for protection of environment. 1. Ionizing radiation sources. Purification of natural and drinking water (review)

International Nuclear Information System (INIS)

Pikaev, AK.

2000-01-01

Review of modern state of the application of ionizing radiations for protection of environment and natural and drinking water purification is presented. Building of installations with electron accelerators with summarized power of beam ∼0.6 MW signifies that application of ionizing radiation for ecological needs increase. It is pointed out that extensible application of electron accelerators is explained by their safety and efficiency as compared with gamma-sources. New information about ionizing radiation sources, radiation-chemical purification of polluted natural and drinking water, mechanisms of processes taking place during treatment by ionizing radiations are generalized [ru

The natural sources of ionizing radiation exposure

International Nuclear Information System (INIS)

Maximilien, R.

1982-01-01

Natural sources of ionizing radiation include external sources (cosmic rays, natural radionuclides present in the crust of the earth and in building materials) and internal sources (naturally occuring radionuclides in the human body, especially the potassium 40 and radon short lived decay products). The principal ways of human exposure to theses different components in ''normal'' areas are reviewed; some examples of the variability of exposure with respect to different regions of the world or the habits of life are given. Actual estimations of the doses delivered to the organs are presented; for the main contributors to population exposure, the conversion into effective dose equivalent has been made for allowing a better evaluation of their respective importance [fr

Teaching about Natural Background Radiation

Science.gov (United States)

Al-Azmi, Darwish; Karunakara, N.; Mustapha, Amidu O.

2013-01-01

Ambient gamma dose rates in air were measured at different locations (indoors and outdoors) to demonstrate the ubiquitous nature of natural background radiation in the environment and to show that levels vary from one location to another, depending on the underlying geology. The effect of a lead shield on a gamma radiation field was also…

Natural background approach to setting radiation standards

International Nuclear Information System (INIS)

Adler, H.I.; Federow, H.; Weinberg, A.M.

1979-01-01

The suggestion has often been made that an additional radiation exposure imposed on humanity as a result of some important activity such as electricity generation would be acceptable if the exposure was small compared to the natural background. In order to make this concept quantitative and objective, we propose that small compared with the natural background be interpreted as the standard deviation (weighted with the exposed population) of the natural background. This use of the variation in natural background radiation is less arbitrary and requires fewer unfounded assumptions than some current approaches to standard-setting. The standard deviation is an easily calculated statistic that is small compared with the mean value for natural exposures of populations. It is an objectively determined quantity and its significance is generally understood. Its determination does not omit any of the pertinent data. When this method is applied to the population of the United States, it suggests that a dose of 20 mrem/year would be an acceptable standard. This is comparable to the 25 mrem/year suggested as the maximum allowable exposure to an individual from the complete uranium fuel cycle

Research on Paramecium aurelia sensitivity factors to natural ionizing radiations

International Nuclear Information System (INIS)

Croute, F.; Soleilhavoup, J.P.; Gros, N.; Planel, H.

1976-01-01

Previous results have demonstrated that the proliferative activity of Paramecium aurelia is linked to the level of natural ionizing radiations since this activity is decreased under radiation protection (lead cell) and increased under chronic exposure to very low dose of 60 Co gamma rays. The results of this investigation indicate that cell sensitivity in spite of variations in natural irradiation levels can be isolated; they are called 'radioresistant' in opposition to 'radiosensitive' cells which present the other response. These characters are being retained for 9 months after the strains have been isolated. On the other hand, in the case of radiosensitive strains, it has been demonstrated that autogamy affected the cell response to background irradiation; no response at all occured on the very day when autogamy took place, but it reached a maximum level 8 days approximately after autogamy. Moreover, it has been proved that the catalase activity of Paramecium aurelia is higher than those already studied in other cell varieties. This great amount of catalase, which seems to vary with the age of cultures after autogamy, could act on Paramecium sensitivity to very low radiation doses [fr

Large-scale fluctuations in the cosmic ionizing background: the impact of beamed source emission

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Suarez, Teresita; Pontzen, Andrew

2017-12-01

When modelling the ionization of gas in the intergalactic medium after reionization, it is standard practice to assume a uniform radiation background. This assumption is not always appropriate; models with radiative transfer show that large-scale ionization rate fluctuations can have an observable impact on statistics of the Lyman α forest. We extend such calculations to include beaming of sources, which has previously been neglected but which is expected to be important if quasars dominate the ionizing photon budget. Beaming has two effects: first, the physical number density of ionizing sources is enhanced relative to that directly observed; and secondly, the radiative transfer itself is altered. We calculate both effects in a hard-edged beaming model where each source has a random orientation, using an equilibrium Boltzmann hierarchy in terms of spherical harmonics. By studying the statistical properties of the resulting ionization rate and H I density fields at redshift z ∼ 2.3, we find that the two effects partially cancel each other; combined, they constitute a maximum 5 per cent correction to the power spectrum P_{H I}(k) at k = 0.04 h Mpc-1. On very large scales (k effects of beaming should be considered when interpreting future observational data sets.

The natural background approach to setting radiation standards

International Nuclear Information System (INIS)

Adler, H.I.; Federow, H.; Weinberg, A.M.

1979-01-01

The suggestion has often been made that an additional radiation exposure imposed on humanity as a result of some important activity such as electricity generation would be acceptable if the exposure was 'small' compared to the natural background. In order to make this concept quantitative and objective, we propose that 'small compared with the natural background' be interpreted as the standard deviation (weighted with the exposed population) of the natural background. We believe that this use of the variation in natural background radiation is less arbitrary and requires fewer unfounded assumptions than some current approaches to standard-setting. The standard deviation is an easily calculated statistic that is small compared with the mean value for natural exposures of populations. It is an objectively determined quantity and its significance is generally understood. Its determination does not omit any of the pertinent data. When this method is applied to the population of the USA, it implies that a dose of 20 mrem/year would be an acceptable standard. This is closely comparable to the 25 mrem/year suggested by the Environmental Protection Agency as the maximum allowable exposure to an individual in the general population as a result of the operation of the complete uranium fuel cycle. Other agents for which a natural background exists can be treated in the same way as radiation. In addition, a second method for determining permissible exposure levels for agents other than radiation is presented. This method makes use of the natural background radiation data as a primary standard. Some observations on benzo(a)pyrene, using this latter method, are presented. (author)

Natural background radiation exposures world-wide

International Nuclear Information System (INIS)

Bennett, B.G.

1993-01-01

The average radiation dose to the world's population from natural radiation sources has been assessed by UNSCEAR to be 2.4 mSv per year. The components of this exposure, methods of evaluation and, in particular, the variations in the natural background levels are presented in this paper. Exposures to cosmic radiation range from 0.26 mSv per year at sea level to 20 times more at an altitude of 6000 m. Exposures to cosmogenic radionuclides ( 3 H, 14 C) are relatively insignificant and little variable. The terrestrial radionuclides 40 K, 238 U, and 232 Th and the decay products of the latter two constitute the remainder of the natural radiation exposure. Wide variations in exposure occur for these components, particularly for radon and its decay products, which can accumulate to relatively high levels indoors. Unusually high exposures to uranium and thorium series radionuclides characterize the high natural background areas which occur in several localized regions in the world. Extreme values in natural radiation exposures have been estimated to range up to 100 times the average values. (author). 15 refs, 3 tabs

Cosmic Metal Production and the Contribution of QSO Absorption Systems to the Ionizing Background

Science.gov (United States)

Madau, Piero; Shull, J. Michael

1996-01-01

The recent discovery by Cowie et al. (1995) and Tytler et al. (1995) of metals in the Ly alpha clouds shows that the intergalactic medium (IGM) at high redshift is contaminated by the products of stars and suggests that ionizing photons from massive star formation may be a significant contributor to the UV background radiation at early epochs. We assess the validity of the stellar photoionization hypothesis. Based on recent computations of metal yields and 0-star Lyman continuum (Lyc) fluxes, we find that 0.2 percent of the rest-mass energy of the metals produced is radiated as Lyc. By modeling the transfer of ionizing radiation through the IGM and the rate of chemical enrichment, we demonstrate that the background intensity of photons at 1 ryd that accompanies the production of metals in the Ly alpha forest clouds may be significant, approaching 0.5 x 10(exp -21) ergs cm squared s(-1) Hz(-1) sr(-1) at z approximately equals 3 if the Lyc escape fraction is greater than of equal to 0.25. Together with quasars, massive stars could then, in principle, provide the hydrogen and helium Lyc photons required to ionize the universe at high redshifts. We propose that observations of the He2 Gunn-Peterson effect and of the metal ionization states of the Ly alpha forest and Lyman-limit absorbers should show the signature of a stellar spectrum. We also note that the stellar photoionization model fails if a large fraction of the UV radiation emitted from stars cannot escape into the IGM, as suggested by the recent Hopkins Ultraviolet Telescope observations by Leitherer et al. (1995) of low-redshift starburst galaxies, or if most of the metals observed at z is approximately 3 were produced at much earlier epochs.

Background radiation levels and standards for protection from ionizing radiations

International Nuclear Information System (INIS)

Farai, I.

1999-01-01

Apart from the amount of radiation which a worker may receive while he performs his work, he is also exposed to radiation because of the nature of his environment. In other words, all individuals are subject to some irradiation even though they may not work with radioactive substances. This source of radiation exposure is often referred to as background radiation. In most environments, it is low-level and can be grouped into two natural and man-made. Background radiation provides the basis on which allowable exposure limits for workers are drawn

Controllable forms of natural background radiation

International Nuclear Information System (INIS)

1988-03-01

RENA is a research programm into the controllable forms of natural background radiation, which cover the activities originating from the naturally occurring radionuclides enhanced by human intervention. In the RENA-program emphasis lays upon the policy aspects of environmental-hygienic, economical and governmental character. (H.W.). 15 refs.; 2 tabs

Spectral characterization of natural backgrounds

Science.gov (United States)

Winkelmann, Max

2017-10-01

As the distribution and use of hyperspectral sensors is constantly increasing, the exploitation of spectral features is a threat for camouflaged objects. To improve camouflage materials at first the spectral behavior of backgrounds has to be known to adjust and optimize the spectral reflectance of camouflage materials. In an international effort, the NATO CSO working group SCI-295 "Development of Methods for Measurements and Evaluation of Natural Background EO Signatures" is developing a method how this characterization of backgrounds has to be done. It is obvious that the spectral characterization of a background will be quite an effort. To compare and exchange data internationally the measurements will have to be done in a similar way. To test and further improve this method an international field trial has been performed in Storkow, Germany. In the following we present first impressions and lessons learned from this field campaign and describe the data that has been measured.

Radiological impact of natural and artificial sources of ionizing radiation. Report UNSCEAR 2000

International Nuclear Information System (INIS)

Cancio, D.

2001-01-01

The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) was established by the General Assembly in 1995. It has the mandate to assess the levels and effects of ionizing radiation. During the last years UNSCEAR has undertaken a broad review of the natural and artificial sources of ionizing radiation. The results of these evaluations have been presented in a Report to the General Assembly with Scientific Annexes including extensive data for the world community (Report UNSCEAR 2000). The greatest contribution to radiation exposure comes from natural background sources. There are considerable variation in the exposures of the population depending on the altitude and latitude, characteristics of the soil and diet and the construction and ventilation features of houses. The global annual average per caput is 2.4 mSv with typical range 1 to 10 mSv. The next largest component comes from medical radiation examinations and treatments with an annual average of 0.4 mSv ranging from 0.04 to 1.0 mSv depending on the level o f medical care. The man-made practices, activities, and events in which radionuclides are released to the environment are always of much concern, but usually they contribute quite low to radiation exposure to humans. Atmospheric testing caused the greatest releases but nowadays very low residual annual levels of exposures persist (0.005 mSv). Nuclear Power production is responsible for only very low exposure and may reach in the future an average annual level of 0.0002 mSv. (Author)

The inception of pulsed discharges in air: simulations in background fields above and below breakdown

Science.gov (United States)

Sun, Anbang; Teunissen, Jannis; Ebert, Ute

2014-11-01

We investigate discharge inception in air, in uniform background electric fields above and below the breakdown threshold. We perform 3D particle simulations that include a natural level of background ionization in the form of positive and \\text{O}2- ions. In background fields below breakdown, we use a strongly ionized seed of electrons and positive ions to enhance the field locally. In the region of enhanced field, we observe the growth of positive streamers, as in previous simulations with 2D plasma fluid models. The inclusion of background ionization has little effect in this case. When the background field is above the breakdown threshold, the situation is very different. Electrons can then detach from \\text{O}2- and start ionization avalanches in the whole volume. These avalanches together create one extended discharge, in contrast to the ‘double-headed’ streamers found in many fluid simulations.

Natural background radiation and oncologic disease incidence

International Nuclear Information System (INIS)

Burenin, P.I.

1982-01-01

Cause and effect relationships between oncologic disease incidence in human population and environmental factors are examined using investigation materials of Soviet and foreign authors. The data concerning US white population are adduced. The role and contribution of natural background radiation oncologic disease prevalence have been determined with the help of system information analysis. The probable damage of oncologic disease is shown to decrease as the background radiation level diminishes. The linear nature of dose-response relationspip has been established. The necessity to include the life history of the studied population along with environmental factors in epidemiological study under conditions of multiplicity of cancerogenesis causes is emphasized

Social economical and psychological considerations in conveying potential radiation risks from high level natural background radiation to the residents of Ramsar, Iran

International Nuclear Information System (INIS)

Mortazavi, S. M. J.; Ghiassi-nejad, M.

2003-01-01

X-rays and radioactivity were discovered more than 100 years ago but the need for protection against very low doses of ionizing radiation and especially different levels of natural radiation is still among the most controversial matters in radiobiology and radiation protection. According to formal reports, some areas in Ramsar, a city in northern Iran, are the inhabited areas with the highest levels of natural radiation studied so far. A population of about 2000 is exposed to average annual radiation levels of 10.2 mGy y''-1 and the highest recorded external gamma dose rates are about 130 mGy y''-1. We have previously shown that in high background radiation areas (HBRAs), cultured human lymphocytes of the inhabitants whose cumulative radiation doses were as much as 170 times more than those of a control area when subjected to 1.5 Gy challenge dose,were significantly more radioresistant compared to the residents of the control area (Mortazavi et al. 2002a,b, Mortazavi and Karam 2002, Ghiassi-Najed et al. 2002). The people who live in these areas are usually unaware of the high levels of natural radiation in their environment. Studies performed on the residents of these areas have indicated that the effective dose of the inhabitants, in some cases, is much higher than the dose limits for occupational irradiation. Considering recent policies of ICRP regarding suggesting dose limits for exposure to natural sources of ionizing including radon, it seems that the inhabitants should become familiar with the possible risks of the exposure to high levels of ionizing radiation. They should also realize that studies performed over the past years have indicated no detrimental effect. On the other hand, according to ICRP suggestions and considering the experiences in other countries, especially evacuation of the residents of contaminated areas after Chernobyl accident, setting any radiation protection regulation for the inhabitants without considering social, economic and

Natural background radiation in Saudi Arabia

International Nuclear Information System (INIS)

Al-Hussan, K.A.; Al-Suliman, K.M.; Wafa, N.F.

1993-01-01

Natural background radiation measurements have been made at numerous locations throughout the world. Little work in this field has been done in developing countries. In this study, the external exposure rates due to natural background radiation sources have been measured for different Saudi Arabian cities. Thermoluminescence dosimeters, CaF 2 Dy(TLD-200), has been used for field measurements. Exposure to TLD's response correlations were obtained for each TLD using a 137 Cs source. A correlation of TLD's response fading at a continuous radiation exposure environment was obtained and applied to correct field measurements. The measurements were taken every two months for a total of six intervals during the whole year. The average measurements of outdoor external exposure rates was found to vary between a minimum of 5.29 μR h -1 in Dammam city and a maximum of 11.59 μR h -1 in Al-Khamis city. (1 fig., 1 tab.)

Recent cosmic microwave background observations and the ionization history of the universe

International Nuclear Information System (INIS)

Hannestad, Steen; Scherrer, Robert J.

2001-01-01

Interest in nonstandard recombination scenarios has been spurred by recent cosmic microwave background (CMB) results from BOOMERANG and MAXIMA, which show an unexpectedly low second acoustic peak, resulting in a best-fit baryon density that is 50% larger than the prediction of big-bang nucleosynthesis (BBN). This apparent discrepancy can be avoided if the universe has a nonstandard ionization history in which the recombination of hydrogen is significantly delayed relative to the standard model. While future CMB observations may eliminate this discrepancy, it is useful to develop a general framework for analyzing nonstandard ionization histories. We develop such a framework, examining nonstandard models in which the hydrogen binding energy E b and the overall expression for the time rate of change of the ionized fraction of electrons are multiplied by arbitrary factors. This set of models includes a number of previously proposed models as special cases. We find a wide range of models with delayed recombination that are able to fit the CMB data with a baryon density in accordance with BBN, but there are even allowed models with earlier recombination than in the standard model. A generic prediction of these models is that the third acoustic CMB peak should be very low relative to what is found in the standard model. This is the case even for the models with earlier recombination than in the standard model, because here the third peak is lowered by an increased diffusion damping at recombination relative to the standard model. Interestingly, the specific height of the third peak depends sensitively on the model parameters, so that future CMB measurements will be able to distinguish between different nonstandard recombination scenarios

Natural background radiation and population dose distribution in India

International Nuclear Information System (INIS)

Nambi, K.S.V.; Bapat, V.N.; David, M.; Sundaram, V.K.; Sunta, C.M.; Soman, S.D.

1986-01-01

A country-wide survey of the outdoor natural background gamma radiation levels has been made using mailed thermoluminescent dosimeters (TLDs). The salient features of the results are: (1) The air-kerma levels and the population doses in various states follow log-normal and normal distributions respectively. (2) The national average value for the air dose (air-kerma) is 775 ± 370 (1σ)μGy/y. (3) The lowest air-kerma recorded is 0.23 mGy/y at Minicoy (Laccadive Islands) and the highest is 26.73 mGy/y at Chavra (monazite areas, Kerala). (4) There are significant temporal variation s (even as high as ± 40 per cent) of the background radiation level at many locations and at least in 10 locations where radon/thoron measurements are available, these could be associated with the seasonal variations in radon/thoron levels. (5) The mail control TLDs indicate a country-wide average value of 785 ± 225 μGy/y for the air-kerma which can be considered to provide a truly national average value for the natural background radiation level in India. (6) The mean natural radiation per caput for the country works out to be 690 ± 200 (1σ) Sv/y. (7) The natural radiation per caput seems to be maximum for Andhra Pradesh (1065 ± 325 μSv/y) and minimum for Maharashtra (370 ± 80 μSv/y). (8) The population dose from the external natural background radiation is estimated to be half a million person-Sievert. (9) Assuming 1 CRP risk factor, it can be estimated that just one out of the 43 cancer deaths occurring on an average per 100,000 population in India, can be attributed to the external natural background radiation. (author). 18 refs., 13 tabs., 9 figs

Resistance of Feather-Associated Bacteria to Intermediate Levels of Ionizing Radiation near Chernobyl.

Science.gov (United States)

Ruiz-González, Mario Xavier; Czirják, Gábor Árpád; Genevaux, Pierre; Møller, Anders Pape; Mousseau, Timothy Alexander; Heeb, Philipp

2016-03-15

Ionizing radiation has been shown to produce negative effects on organisms, although little is known about its ecological and evolutionary effects. As a study model, we isolated bacteria associated with feathers from barn swallows Hirundo rustica from three study areas around Chernobyl differing in background ionizing radiation levels and one control study site in Denmark. Each bacterial community was exposed to four different γ radiation doses ranging from 0.46 to 3.96 kGy to test whether chronic exposure to radiation had selected for resistant bacterial strains. Experimental radiation duration had an increasingly overall negative effect on the survival of all bacterial communities. After exposure to γ radiation, bacteria isolated from the site with intermediate background radiation levels survived better and produced more colonies than the bacterial communities from other study sites with higher or lower background radiation levels. Long-term effects of radiation in natural populations might be an important selective pressure on traits of bacteria that facilitate survival in certain environments. Our findings indicate the importance of further studies to understand the proximate mechanisms acting to buffer the negative effects of ionizing radiation in natural populations.

Natural radiation background in the ancient city of Palmyra

International Nuclear Information System (INIS)

Shweikani, R.; Al-Masri, M.S.; Hushari, M.; Raja, G.; Aissa, M.; Al-Hent, R.

2012-01-01

Natural radiation background has been determined for the Ancient City of Palmyra and its surrounding areas. Car-borne gamma spectrometry, indoor radon gas concentration and natural radionuclides levels in environmental samples (soil, water and plants) have been determined. Two types of dwelling were involved in this study, one with cancer cases, and the others without. The results showed that indoor radon gas concentrations and radiation exposure rates are within reported mean background levels in Syria (45 Bq m −3 and less than 0.1 μSv h −1 , respectively); no differences were noticed between the dwelling groups. In addition, the results did not indicate any relation between recorded cancers and measured natural radioactivity.

Demonstration of a stimulating effect of natural ionizing radiation and of very low radiation doses on cell multiplication

International Nuclear Information System (INIS)

Planel, G.; Soleilhavoup, J.P.; Tixador, R.; Croute, F.; Richoilley, G.

1976-01-01

Experiments have been carried out to demonstrate a possible effect of natural ionizing radiation. Using lead shielding devices or an underground laboratory, it was shown that a decrease in background irradiation induces a decrease in cell growth rate (experiments carried out on Paramecia). On the other hand, the recovery of a normal irradiation level in shielding devices induces a quite normal cell proliferation. Moreover, small doses of γ rays from 60 Co exhibit a stimulating effect. Variations in cell radiosensitivity to these low doses are reported. Experiments carried out in the underground laboratory and at high altitude show that both telluric radioactivity and cosmic rays contribute to this stimulating effect on cell multiplication. (author)

Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

Directory of Open Access Journals (Sweden)

Marie Ragon

Full Text Available BACKGROUND: The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. METHODOLOGY/PRINCIPAL FINDINGS: To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta and ascomycete fungi (Ascomycota dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. CONCLUSIONS/SIGNIFICANCE: Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in

Sunlight-Exposed Biofilm Microbial Communities Are Naturally Resistant to Chernobyl Ionizing-Radiation Levels

Science.gov (United States)

Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

2011-01-01

Background The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. Methodology/Principal Findings To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Conclusions/Significance Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general

Hygiene of ionizing radiations

International Nuclear Information System (INIS)

Legare, I.-M.; Conceicao Cunha, M. da

1976-01-01

The concepts of quality factor and rem are introduced and a table of biological effects of external ionizing radiation sources is presented. Natural exposures, with tables of background radiation sources and of doses due to cosmic rays on high altitude areas and their populations are treated, as well as medical exposures; artificial background; fallout; scientific, industrial and other sources. The maximum and limit doses for man are given and tables of maximum admissible doses of ionizing radiations for 16-18 year old workers professionaly exposed, for professionals eventually subjected to radiation in their work and for people eventually exposed. Professional protection is discussed and tables are given of half-value layer of water, concrete, iron and lead for radiations of different energies, as well as the classification of exposure zones to the radiations and of maximum acceptable contamination for surfaces. The basic safety standards for radiation protection are summarized; tables are given also with emergency references for internal irradiation. Procedures with patients which received radioisotopes are discussed. At last, consideration is given to the problem of radioactive wastes in connection with the medical use of radionuclides [pt

Natural background radiation in Jordan

International Nuclear Information System (INIS)

Daoud, M.N.S.

1997-01-01

An Airborne Gamma Ray survey has been accomplished for Jordan since 1979. A complete report has been submitted to the Natural Resources Authority along with field and processed data ''digital and analogue''. Natural radioelements concentration is not provided with this report. From the corrected count rate data for each natural radioelement, Concentrations and exposure rates at the ground level were calculated. Contoured maps, showing the exposure rates and the dose rates were created. Both maps reflect the surface geology of Jordan, where the Phosphate areas are very well delineated by high-level contours. In southeastern Jordan the Ordovician sandstone, which contain high percentage of Th (around 2000 ppm in some places) and a moderate percentage of U (about 300 ppm), also show high gamma radiation exposures compared with the surrounding areas. Comparing the values of the exposure rates given in (μR/h) to those obtained from other countries such as United States, Canada, Germany, etc. Jordan shows higher background radiation which reach two folds and even more than those in these countries. More detailed studies should be performed in order to evaluate the radiological risk limits on people who are living in areas of high radiation such that the area of the phosphatic belt which covers a vast area of Jordan high Plateau. (author)

Extraction and comparison of proteins from natural rubber latex by conventional and ionizing radiation methods

International Nuclear Information System (INIS)

Rogero, Sizue O.; Spencer, Patrick J.; Campos, Vania E.; Lusvarghi, Fabio M.; Higa, Olga Z.

1997-01-01

Several proteins in natural rubber latex (NRL) have been assigned to be significant allergens. It is known that proteins submitted to ionizing radiation suffer denaturation and immunochemical modification resulting in low antigenic reactivity. The aim of this study was to extract and compare water extractable proteins from NRL films vulcanized by conventional and by ionizing radiation methods. SDS-polyacrylamide gel electrophoresis (SDS--PAGE) and high pressure liquid chromatography (HPLC) showed a diffuse protein band of about 14 KDa, which we believe is rubber elongation factor (REF), in both eluates, but smaller in latex film vulcanized by ionizing radiation. REF has been suggested to be a major latex allergen. These data suggest that ionizing radiation vulcanization could be an useful method for the production of NRL goods with low antigenicity. (author). 8 refs., 2 figs., 1 tab

Natural background radiation in Jordan

Energy Technology Data Exchange (ETDEWEB)

Daoud, M N.S. [National Resources Authority, Ministry of Energy and Mineral Resources, Amman (Jordan)

1997-11-01

An Airborne Gamma Ray survey has been accomplished for Jordan since 1979. A complete report has been submitted to the Natural Resources Authority along with field and processed data ``digital and analogue``. Natural radioelements concentration is not provided with this report. From the corrected count rate data for each natural radioelement, Concentrations and exposure rates at the ground level were calculated. Contoured maps, showing the exposure rates and the dose rates were created. Both maps reflect the surface geology of Jordan, where the Phosphate areas are very well delineated by high-level contours. In southeastern Jordan the Ordovician sandstone, which contain high percentage of Th (around 2000 ppm in some places) and a moderate percentage of U (about 300 ppm), also show high gamma radiation exposures compared with the surrounding areas. Comparing the values of the exposure rates given in ({mu}R/h) to those obtained from other countries such as United States, Canada, Germany, etc. Jordan shows higher background radiation which reach two folds and even more than those in these countries. More detailed studies should be performed in order to evaluate the radiological risk limits on people who are living in areas of high radiation such that the area of the phosphatic belt which covers a vast area of Jordan high Plateau. (author). 8 refs, 10 figs, 7 tabs.

Modeling Natural Space Ionizing Radiation Effects on External Materials

Science.gov (United States)

Alstatt, Richard L.; Edwards, David L.; Parker, Nelson C. (Technical Monitor)

2000-01-01

Predicting the effective life of materials for space applications has become increasingly critical with the drive to reduce mission cost. Programs have considered many solutions to reduce launch costs including novel, low mass materials and thin thermal blankets to reduce spacecraft mass. Determining the long-term survivability of these materials before launch is critical for mission success. This presentation will describe an analysis performed on the outer layer of the passive thermal control blanket of the Hubble Space Telescope. This layer had degraded for unknown reasons during the mission, however ionizing radiation (IR) induced embrittlement was suspected. A methodology was developed which allowed direct comparison between the energy deposition of the natural environment and that of the laboratory generated environment. Commercial codes were used to predict the natural space IR environment model energy deposition in the material from both natural and laboratory IR sources, and design the most efficient test. Results were optimized for total and local energy deposition with an iterative spreadsheet. This method has been used successfully for several laboratory tests at the Marshall Space Flight Center. The study showed that the natural space IR environment, by itself, did not cause the premature degradation observed in the thermal blanket.

Natural background radiation and population dose in China

Energy Technology Data Exchange (ETDEWEB)

Guangzhi, C. (Ministry of Public Health, Beijing, BJ (China)); Ziqiang, P.; Zhenyum, H.; Yin, Y.; Mingqiang, G.

On the basis of analyzing the data for the natural background radiation level in China, the typical values for indoor and outdoor terrestrial gamma radiation and effective dose equivalents from radon and thoron daughters are recommended. The annual effective dose equivalent from natural radiation to the inhabitant is estimated to be 2.3 mSv, in which 0.54 mSv is from terrestrial gamma radiation and about 0,8 mSv is from radon and its short-lived daughters. 55 Refs.

Estimation of thyroid gland state of voles natural populations from increased radioactive background territories

Energy Technology Data Exchange (ETDEWEB)

Raskosha, O.; Ermakova, O.; Kaneva, A. [Institute of Biology of Komi Scientific Center, Ural Division of Russian Academy of Science (Russian Federation)

2014-07-01

Investigation of effects caused in biological objects by chronic low-intensity radiation in their natural habitats is one of the most important problems of modern radioecology. The aim of our work - complex estimation of state of thyroid gland of voles inhabiting increased radioactive background territories. We investigated tundra voles (Microtus oeconomus Pall.) that were sampled at different stages of population cycle from the experimental and the control sites in the Uhta region of the Komi Republic, Russia. Experimental site contamination resulted from commercial extraction od radium between the 1930's and 1950's. Irradiation exposure dose at the site was 50-2000 mR/h (at the control site 10-15 mR/h). Complex estimation of thyroid was made by histological, morpho-metrical, radioimmunological and cytogenetic methods. Results showed high sensitivity of thyroid gland of tundra voles from chronically irradiated natural populations. We found reliable changes in morphological features of thyroid, in the level of thyroidal hormones and increased frequency of cells with micro-nucleuses in animals sampled from the experimental site as compared with the control ones. It was also showed, that chronic exposure of ionizing irradiation at the same range of absorbed doses can cause different effects in animals depending on sex, age and the stage of population cycle. This confirms the need of including these biological factors to analysis of low doses effects in the natural populations during radioecological studies. Investigations were supported by RFBR grants No. 13-04-01750? and No. 13-04-90351-RBUa. Document available in abstract form only. (authors)

Ionization front accelerator

International Nuclear Information System (INIS)

Olson, C.L.

1975-01-01

In a recently proposed linear collective accelerator, ions are accelerated in a steep, moving potential well created at the head of an intense relativistic electron beam. The steepness of the potential well and its motion are controlled by the external ionization of a suitable background gas. Calculations concerning optimum choices for the background gas and the ionization method are presented; a two-step photoionization process employing Cs vapor is proposed. In this process, a super-radiant light source is used to excite the gas, and a UV laser is used to photoionize the excited state. The appropriate line widths and coupled ionization growth rate equations are discussed. Parameter estimates are given for a feasibility experiment, for a 1 GeV proton accelerator, and for a heavy ion accelerator (50 MeV/nucleon uranium). (auth)

Laser-enhanced ionization spectroscopy around the ionization limit

International Nuclear Information System (INIS)

Axner, O.; Berglind, T.; Sjoestroem, S.

1986-01-01

Laser-induced photoionization and Laser-Enhanced collision Ionization (LEI) of Na, Tl, and Li in flames are detected by measuring the production of charges following a laser excitation. The ionization signal is investigated for excitations of the atoms from lower lying states both to Rydberg states close to the ionization limit, as well as to continuum states, i.e. the process of collision ionization is compared with that of photoionization. The qualitative behaviour of the ionization signal when scanning across the ionization limit is studied. It is shown that the ionization signal has a smooth behaviour when passing from bound states into continuum states. The laser-induced photoionization signal strength of atoms in flames is both calculated and measured and a good agreement is obtained. A calculation of wavelength dependent photoionization signal strengths for a number of elements is also presented. Photoionization is used to determine flame- and geometry-dependent parameters. An implication of photoionization in connection with LEI spectrometry for trace element analysis is that there will be a significant increase in background noise if the sample contains high concentrations of easily photoionizing elements and short wavelength light is used. (orig.)

A New Method to Measure the Post-reionization Ionizing Background from the Joint Distribution of Lyα and Lyβ Forest Transmission

Science.gov (United States)

Davies, Frederick B.; Hennawi, Joseph F.; Eilers, Anna-Christina; Lukić, Zarija

2018-03-01

The amplitude of the ionizing background that pervades the intergalactic medium (IGM) at the end of the epoch of reionization provides a valuable constraint on the emissivity of the sources that reionized the universe. While measurements of the ionizing background at lower redshifts rely on a simulation-calibrated mapping between the photoionization rate and the mean transmission of the Lyα forest, at z ≳ 6 the IGM becomes increasingly opaque and transmission arises solely in narrow spikes separated by saturated Gunn–Peterson troughs. In this regime, the traditional approach of measuring the average transmission over large ∼50 Mpc/h regions is less sensitive and suboptimal. In addition, the five times smaller oscillator strength of the Lyβ transition implies that the Lyβ forest is considerably more transparent at z ≳ 6, even in the presence of contamination by foreground z ∼ 5 Lyα forest absorption. In this work we present a novel statistical approach to analyze the joint distribution of transmission spikes in the cospatial z ∼ 6 Lyα and Lyβ forests. Our method relies on approximate Bayesian computation (ABC), which circumvents the necessity of computing the intractable likelihood function describing the highly correlated Lyα and Lyβ transmission. We apply ABC to mock data generated from a large-volume hydrodynamical simulation combined with a state-of-the-art model of ionizing background fluctuations in the post-reionization IGM and show that it is sensitive to higher IGM neutral hydrogen fractions than previous techniques. As a proof of concept, we apply this methodology to a real spectrum of a z = 6.54 quasar and measure the ionizing background from 5.4 ≤ z ≤ 6.4 along this sightline with ∼0.2 dex statistical uncertainties. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the

Radiation hormesis: an outcome of exposure to low level ionizing radiation

International Nuclear Information System (INIS)

Kant, Krishan

2012-01-01

Ionizing radiation is a benign environmental agent at background levels. Human population is always exposed to ionizing radiation from natural sources. Important sources are cosmic rays which come from outer space and from the surface of the sun, terrestrial radionuclides which occur in the earths crust in various geological formations in soils, rocks, building materials, plants, water, food, air and in the human body itself. With the increasing use of radiation in health facilities, scientific research, industry and agriculture, the study of impact of low-level ionizing radiation on environment and possible health effects on future generations has been a cause of concern in recent years. As regards the effects, it is established fact that high doses of ionizing radiation are harmful to health, there exists, however, a substantial controversy regarding the effects of low doses of ionizing radiation (LLIR). In the present paper, brief review of the available literature, data and reports on stimulation by low-dose irradiation and recent data supporting radiation hormesis. A linear quadratic model has been given illustrating the validity of radiation hormesis, besides the comparison of the dose rates arising from natural and manmade sources to the Indian population. This overview summarizes various reports

Non-Ionizing Radiation: Nature and Protection

International Nuclear Information System (INIS)

Abukasem, E.; Abdemalek, H.; Mosbah, D. S.

2011-01-01

Last century, the humanity witnessed a vast development, after the industrial revolution, in many aspects of life. There was a real revolution in world of communications, the electromagnetic waves were produced and used in many applications like wireless communications, radio and television transmissions, information transfer, medical diagnosis and many other useful applications. Non-ionizing radiation, the radiation which has no enough energy to remove an electron from an atom, becomes indispensable life necessity and currently it is a subject of public debate about its effects and hazards on human life and environments. The Arab Atomic Energy Agency recognized this fact and tried to raise the public awareness towards by organizing seminars, workshops and expert meetings in the Arab region in order to study the theoretical and applies aspects of this type of radiation as well as to shed the light on its possible hazards and effects on human life. This booklet came as a result of many expert meetings to be an Arabic simple and comprehensive guide line about the nature of and the different methods of protection from its possible effects and hazards.(author)

Monitoring of Natural Soil Radioactivity with Portable Gamma-Ray Spectrometers

DEFF Research Database (Denmark)

Bøtter-Jensen, Lars; Løvborg, Leif; Kirkegaard, Peter

1979-01-01

Two portable NaI(Tl) spectrometers with four energy windows were used for the recording of gamma-ray counts over soil and rock of differing natural radioactivity. The exposure rates at the field sites were simultaneously measured with a high-pressure argon ionization chamber. Background measureme......Two portable NaI(Tl) spectrometers with four energy windows were used for the recording of gamma-ray counts over soil and rock of differing natural radioactivity. The exposure rates at the field sites were simultaneously measured with a high-pressure argon ionization chamber. Background...... measurements at sea were carried out in order to estimate the non-terrestrial contributions to the instrument readings. Counts recorded in the three high-energy windows of the spectrometers were converted into radiometrically equivalent concentrations of thorium, uranium, and potassium in the ground. Large....... The theoretical exposure rates deducible from the experimental radioelement concentrations at the field sites were in good agreement both with the ionization-chamber readings (corrected for cosmic-ray background) and with the exposure rates measured by total gamma-ray counting. From this and other results...

Ionization of cloud and intercloud hydrogen by O and B stars

International Nuclear Information System (INIS)

Elmergreen, B.G.

1975-01-01

Lyman continuum radiation from OB stars may be the primary source of ionization of interstellar hydrogen. Eighty percent of Lyman continuum photons produced by these stars comes from a very small number of 05 and 06 stars, however, and if this radiation is ionized to interstellar hydrogen with the high degree of uniformity indicated by pulsar dispersion measures or by the diffuse background of Hα emission, then each 05 or 06 star must be able to maintain an H II region over a distance of several hundred parsecs. The cloudy structure of interstellar space prevents such long range ionization, however, and a large fraction of the stellar Lyman continuum photons will be converted to Balmer photons in the high-density ionized surfaces of the exposed clouds. Two questions concerning this cloudy obscuration naturally arise: what will be the consequences of a cloud's exposure to Lyman continuum radiation, and to what extent can low-density, intercloud hydrogen be ionized in the obscured regions. These questions are considered

On the role of natural radiation background in the initial development of plants

International Nuclear Information System (INIS)

Kuzin, A.M.; Vagabova, M.Eh.; Primak-Mirolyubov, V.N.

1977-01-01

To obtain data on plant development under strictly controlled decreased natural radiation conditions, the experiment with radish seeds was conducted in a special chamber having a decreased natural radiation background. It has been shown that the development of seedlings in the course of the first 4-5 days in significantly delayed, and it normalizes when radiation sources, imitating the natural radiation background, are placed inside the chamber

Measurement of natural background radiation intensity on a train

International Nuclear Information System (INIS)

Chen, Y. F.; Lin, J. W.; Sheu, R. J.; Lin, U. T.; Jiang, S. H.

2011-01-01

This work aims to measure different components of natural background radiation on a train. A radiation measurement system consisting of four types of radiation detectors, namely, a Berkeley Lab cosmic-ray detector, moderated 3He detector, high pressure ionisation chamber and NaI(Tl) spectrometer, associated with a global positioning system unit was established for this purpose. For the commissioning of the system, a test measurement on a train along the railway around the northern Taiwan coast from Hsinchu to Hualien with a distance of ∼275 km was carried out. No significant variation of the intensities of the different components of natural background radiation was observed, except when the train went underground or in the tunnels. The average external dose rate received by the crew of the train was estimated to be 62 nSv h -1 . (authors)

Natural background gamma-ray spectrum. List of gamma-rays ordered in energy from natural radionuclides

International Nuclear Information System (INIS)

Ichimiya, Tsutomu; Narita, Tsutomu; Kitao, Kensuke.

1998-03-01

A quick index to γ-rays and X-rays from natural radionuclides is presented. In the list, γ-rays are arranged in order of increasing energy. The list also contains γ-rays from radioactive nuclides produced in a germanium detector and its surrounding materials by interaction with cosmic neutrons, as well as direct γ-rays from interaction with the neutrons. Artificial radioactive nuclides emitting γ-rays with same or near energy value as that of the natural γ-rays and X-rays are also listed. In appendix, γ-ray spectra from a rock, uranium ore, thorium, monazite and uraninite and also background spectra obtained with germanium detectors placed in iron or lead shield have been given. The list is designed for use in γ-ray spectroscopy under the conditions of highly natural background, such as in-situ environmental radiation monitoring or low-level activity measurements, with a germanium detector. (author)

Natural background gamma-ray spectrum. List of gamma-rays ordered in energy from natural radionuclides

Energy Technology Data Exchange (ETDEWEB)

Ichimiya, Tsutomu [Japan Radioisotope Association, Tokyo (Japan); Narita, Tsutomu; Kitao, Kensuke

1998-03-01

A quick index to {gamma}-rays and X-rays from natural radionuclides is presented. In the list, {gamma}-rays are arranged in order of increasing energy. The list also contains {gamma}-rays from radioactive nuclides produced in a germanium detector and its surrounding materials by interaction with cosmic neutrons, as well as direct {gamma}-rays from interaction with the neutrons. Artificial radioactive nuclides emitting {gamma}-rays with same or near energy value as that of the natural {gamma}-rays and X-rays are also listed. In appendix, {gamma}-ray spectra from a rock, uranium ore, thorium, monazite and uraninite and also background spectra obtained with germanium detectors placed in iron or lead shield have been given. The list is designed for use in {gamma}-ray spectroscopy under the conditions of highly natural background, such as in-situ environmental radiation monitoring or low-level activity measurements, with a germanium detector. (author)

Mode shape and natural frequency identification for seismic analysis from background vibration

International Nuclear Information System (INIS)

Bhan, S.; Wozniak, Z.

1986-02-01

The feasibility of calculating natural frequencies and mode shapes of major equipment in a CANDU reactor from the measurements of their response to background excitation has been studied. A review of vibration data measured at various locations in CANDU plants shows that structures responded to a combination of random and harmonic background excitation. Amplitude of measured vibration is sufficient to allow meaningful data analysis. Frequency content in the 0 to 50-Hz range, which is of interest for earthquake response, is present in some of the vibration measurements studied. Spectral techniques have been developed for determining the response function of structures from measured vibration response to background excitation. The natural frequencies and mode shapes are then evaluated graphically from the frequency function plots. The methodology has been tested on a simple cantilever beam with known natural frequencies and mode shapes. The comparison between the theoretical and the computed natural frequencies and mode shapes is good for the lower modes. However, better curve-fitting techniques will be required in future, especially for higher modes. Readily available equipment necessary for the measurement of background vibration in a CANDU plant (which is commercially available) has been identified. An experimental program has been proposed to verify the methodology developed in this study. Recommendations are also made to study methods to improve the accuracy of the mode shape and natural frequency prediction

Policy implications with regard to controllable forms of natural background radiation

International Nuclear Information System (INIS)

Heijningen, R.J.J. van; Bartels, J.H.M.; Ackers, J.G.; Hogeweg, B.; Rijn, H.T.U. de; Walle, F.B. de

1988-04-01

The RENA (Regulable forms of Natural Background radiation) has started in order to broaden the technical-scientific insights in the domain of the natural background radiation and to continue the SAWORA-study. With regard to the policy implications it has appeared to be desirable to define more detailed the environment-protectional economical and governmental aspects and to consider their mutual relationships in order to prepare a coherent programme which is directed at policy actions to be undertaken as well as at the supporting study needed. (author). 34 refs.; 3 figs.; 11 tabs

Assessment of natural background radiation in one of the highest regions of Ecuador

Science.gov (United States)

Pérez, Mario; Chávez, Estefanía; Echeverría, Magdy; Córdova, Rafael; Recalde, Celso

2018-05-01

Natural background radiation was measured in the province of Chimborazo (Ecuador) with the following reference coordinates 1°40'00''S 78°39'00''W, where the furthest point to the center of the planet is located. Natural background radiation measurements were performed at 130 randomly selected sites using a Geiger Müller GCA-07W portable detector; these measurements were run at 6 m away from buildings or walls and 1 m above the ground. The global average natural background radiation established by UNSCEAR is 2.4 mSv y-1. In the study area measurements ranged from 0.57 mSv y-1 to 3.09 mSv y-1 with a mean value of 1.57 mSv y-1, the maximum value was recorded in the north of the study area at 5073 metres above sea level (m.a.s.l.), and the minimum value was recorded in the southwestern area at 297 m.a.s.l. An isodose map was plotted to represent the equivalent dose rate due to natural background radiation. An analysis of variance (ANOVA) between the data of the high and low regions of the study area showed a significant difference (p < α), in addition a linear correlation coefficient of 0.92 was obtained, supporting the hypothesis that in high altitude zones extraterrestrial radiation contributes significantly to natural background radiation.

SU-F-T-166: On the Nature of the Background Visible Light Observed in Fiber Optic Dosimetry of Proton Beams

Energy Technology Data Exchange (ETDEWEB)

Darafsheh, A; Kassaee, A; Finlay, J [University of Pennsylvania, Philadelphia, PA (United States); Taleei, R [UT Southwestern Medical Center, Dallas, TX (United States)

2016-06-15

Purpose: The nature of the background visible light observed during fiber optic dosimetry of proton beams, whether it is due to Cherenkov radiation or not, has been debated in the literature recently. In this work, experimentally and by means of Monte Carlo simulations, we shed light on this problem and investigated the nature of the background visible light observed in fiber optics irradiated with proton beams. Methods: A bare silica fiber optics was embedded in tissue-mimicking phantoms and irradiated with clinical proton beams with energies of 100–225 MeV at Roberts Proton Therapy Center. Luminescence spectroscopy was performed by a CCD-coupled spectrograph to analyze in detail the emission spectrum of the fiber tip across the visible range of 400–700 nm. Monte Carlo simulation was performed by using FLUKA Monte Carlo code to simulate Cherenkov light and ionizing radiation dose deposition in the fiber. Results: The experimental spectra of the irradiated silica fiber shows two distinct peaks at 450 and 650 nm, whose spectral shape is different from that of Cherenkov radiation. We believe that the nature of these peaks are connected to the point defects of silica including oxygen-deficiency center (ODC) and non-bridging oxygen hole center (NBOHC). Monte Carlo simulations confirmed the experimental observations that Cherenkov radiation cannot be solely responsible for such a signal. Conclusion: We showed that Cherenkov radiation is not the dominant visible signal observed in bare fiber optics irradiated with proton beams. We observed two distinct peaks at 450 and 650 nm whose nature is connected with the point defects of silica fiber including oxygen-deficiency center and non-bridging oxygen hole center.

Speech recognition in natural background noise.

Directory of Open Access Journals (Sweden)

Julien Meyer

Full Text Available In the real world, human speech recognition nearly always involves listening in background noise. The impact of such noise on speech signals and on intelligibility performance increases with the separation of the listener from the speaker. The present behavioral experiment provides an overview of the effects of such acoustic disturbances on speech perception in conditions approaching ecologically valid contexts. We analysed the intelligibility loss in spoken word lists with increasing listener-to-speaker distance in a typical low-level natural background noise. The noise was combined with the simple spherical amplitude attenuation due to distance, basically changing the signal-to-noise ratio (SNR. Therefore, our study draws attention to some of the most basic environmental constraints that have pervaded spoken communication throughout human history. We evaluated the ability of native French participants to recognize French monosyllabic words (spoken at 65.3 dB(A, reference at 1 meter at distances between 11 to 33 meters, which corresponded to the SNRs most revealing of the progressive effect of the selected natural noise (-8.8 dB to -18.4 dB. Our results showed that in such conditions, identity of vowels is mostly preserved, with the striking peculiarity of the absence of confusion in vowels. The results also confirmed the functional role of consonants during lexical identification. The extensive analysis of recognition scores, confusion patterns and associated acoustic cues revealed that sonorant, sibilant and burst properties were the most important parameters influencing phoneme recognition. . Altogether these analyses allowed us to extract a resistance scale from consonant recognition scores. We also identified specific perceptual consonant confusion groups depending of the place in the words (onset vs. coda. Finally our data suggested that listeners may access some acoustic cues of the CV transition, opening interesting perspectives for

Speech recognition in natural background noise.

Science.gov (United States)

Meyer, Julien; Dentel, Laure; Meunier, Fanny

2013-01-01

In the real world, human speech recognition nearly always involves listening in background noise. The impact of such noise on speech signals and on intelligibility performance increases with the separation of the listener from the speaker. The present behavioral experiment provides an overview of the effects of such acoustic disturbances on speech perception in conditions approaching ecologically valid contexts. We analysed the intelligibility loss in spoken word lists with increasing listener-to-speaker distance in a typical low-level natural background noise. The noise was combined with the simple spherical amplitude attenuation due to distance, basically changing the signal-to-noise ratio (SNR). Therefore, our study draws attention to some of the most basic environmental constraints that have pervaded spoken communication throughout human history. We evaluated the ability of native French participants to recognize French monosyllabic words (spoken at 65.3 dB(A), reference at 1 meter) at distances between 11 to 33 meters, which corresponded to the SNRs most revealing of the progressive effect of the selected natural noise (-8.8 dB to -18.4 dB). Our results showed that in such conditions, identity of vowels is mostly preserved, with the striking peculiarity of the absence of confusion in vowels. The results also confirmed the functional role of consonants during lexical identification. The extensive analysis of recognition scores, confusion patterns and associated acoustic cues revealed that sonorant, sibilant and burst properties were the most important parameters influencing phoneme recognition. . Altogether these analyses allowed us to extract a resistance scale from consonant recognition scores. We also identified specific perceptual consonant confusion groups depending of the place in the words (onset vs. coda). Finally our data suggested that listeners may access some acoustic cues of the CV transition, opening interesting perspectives for future studies.

Proceedings of the 15. Berzelius symposium on somatic and genetic effects of ionizing radiation

International Nuclear Information System (INIS)

Stigbrand, T.

1989-01-01

The symposium begins with a brush up on the physics of ionizing radiation and a background to the natural and man-made source of radiation to which we are exposed. The next section deals with the origin and nature of radiation-induced damage to DNA. The somatic effects of ionizing radiation span from DNA lesions to various effects on cell structure and cell function and effects on whole organs. The somatic effects are immediate as well as long-term, with mental impairment and an increased risk for carcinogenesis as consequences of main concern. The genetic effects of ionizing radiation can result in: infertility, spontaneous abortions, genetic diseases and malformations and increased risk for cancer. This leads over to the problems of risk estimation. Risk estimation which is mainly based on experimental data using animal models, human cell lines and epidemiological studies of exposed and unexposed populations

Development of natural radiation model for evaluation of background radiation in radiation portal monitor

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Bum; Lee, Jin Hyung; Moon, Myung Kook [Radioisotope Research and Development Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-11-15

In ports and airports, radiation portal monitors (RPM) are deployed to detect illicit radioactive materials. Detected gamma rays in a RPM include background radiation and radiation from a freight. As a vehicle moves through the RPM, the vehicle causes the fluctuations in the natural background radiation signal, which ranges of up to 30%. The fluctuation increases the uncertainty of detection signal and can be a cause of RPM false alarm. Therefore, it is important to evaluate background radiation as well as radiation from a container. In this paper, a natural background radiation model was developed to evaluate RPM. To develop natural background radiation model, a Monte Carlo simulation was performed and compared with experimental measurements from a RPM for {sup 40}K, {sup 232}Th series, and {sup 235}U series, which are major sources of natural background radiation. For a natural radiation source, we considered a cylindrical soil volume with 300 m radius and 1 m depth, which was estimated as the maximum range affecting the RPM by MCNP6 simulation. The volume source model was converted to surface source by using MCNP SSW card for computational efficiency. The computational efficiency of the surface source model was improved to approximately 200 times better than that of the volume source model. The surface source model is composed of a hemisphere with 20 m radius in which the RPM and container are modelled. The natural radiation spectrum from the simulation was best fitted to the experimental measurement when portions of {sup 40}K, {sup 232}Th series, and {sup 235}U series were 0.75, 0.0636, and 0.0552 Bq·g{sup -1}, respectively. For gross counting results, the difference between simulation and experiment was around 5%. The background radiation model was used to evaluate background suppression from a 40 ft container with 7.2 m·s{sup -1} speed. In further study, background models and freight models for RPM in real container ports will be developed and applied to

Unique signatures of natural background radiation on human Y chromosomes from Kerala, India.

Directory of Open Access Journals (Sweden)

Sanjay Premi

Full Text Available The most frequently observed major consequences of ionizing radiation are chromosomal lesions and cancers, although the entire genome may be affected. Owing to its haploid status and absence of recombination, the human Y chromosome is an ideal candidate to be assessed for possible genetic alterations induced by ionizing radiation. We studied the human Y chromosome in 390 males from the South Indian state of Kerala, where the level of natural background radiation (NBR is ten-fold higher than the worldwide average, and that from 790 unexposed males as control.We observed random microdeletions in the Azoospermia factor (AZF a, b and c regions in >90%, and tandem duplication and copy number polymorphism (CNP of 11 different Y-linked genes in about 80% of males exposed to NBR. The autosomal homologues of Y-linked CDY genes largely remained unaffected. Multiple polymorphic copies of the Y-linked genes showing single Y-specific signals suggested their tandem duplication. Some exposed males showed unilocus duplication of DAZ genes resulting in six copies. Notably, in the AZFa region, approximately 25% of exposed males showed deletion of the DBY gene, whereas flanking genes USP9Y and UTY remained unaffected. All these alterations were detected in blood samples but not in the germline (sperm samples.Exposure to high levels of NBR correlated with several interstitial polymorphisms of the human Y chromosome. CNPs and enhanced transcription of the SRY gene after duplication are envisaged to compensate for the loss of Y chromosome in some cells. The aforesaid changes, confined to peripheral blood lymphocytes, suggest a possible innate mechanism protecting the germline DNA from the NBR. Genome analysis of a larger population focusing on greater numbers of genes may provide new insights into the mechanisms and risks of the resultant genetic damages. The present work demonstrates unique signatures of NBR on human Y chromosomes from Kerala, India.

Worldwide exposures to ionizing radiation

International Nuclear Information System (INIS)

Bennett, B.G.

1993-01-01

All of mankind is exposed to ionizing radiation from natural sources, from human practices that release natural and artificial radionuclides to the environment, and from medical radiation procedures. This paper reviews the assessment in the UNSCEAR 1993 Report of the exposures of human populations worldwide to the various sources of ionizing radiation

Regulatory control of natural ionizing sources in Lithuania: Experience based on indoor radon monitoring

International Nuclear Information System (INIS)

Mastauskas, A.; Morkunas, G.

1997-01-01

The situation in legislation of protection against risks from natural sources of ionizing radiation in Lithuania is described. The requirements of new standards came into conflict with the real situation which has not been evaluated before implementation of these standards. On the basis of recommendations of ICRP Publication 60 and results of indoor radon survey new action levels are being established. (author)

Effects of autogamy in Paramecium tetraurelia on catalase activity and on radiosensitivity to natural ionizing radiations

International Nuclear Information System (INIS)

Croute, F.; Dupouy, D.; Charley, J.P.; Soleilhavoup, J.P.; Planel, H.

1980-01-01

Catalase activity of Paramecium tetraurelia decreased during autogamy and recovered to normal 5 days later. Autogamy also caused changes in the ciliate's sensitivity sensitivity to natural ionizing radiations - the decrease in cell growth rate previously described in shielded cultures did not occur when autogamous cells were used. Maximum effect of shielding was observed in 11-day-old postautogamous cells. The role of the catalase in the mechanism of natural irradiation effect is discussed

Experiments on how photo- and background ionization affect positive streamers: oxygen concentration, repetition and radioactivity

NARCIS (Netherlands)

Nijdam, S.; Veldhuizen, van E.M.; Ebert, U.

2011-01-01

Positive streamers in air and other oxygen-nitrogen mixtures are generally believed to propagate against the electron drift direction due to photo-ionization. Photo-ionization is the non-local ionization of O2-molecules by UV radiation from excited N2-molecules. This facilitates the streamer

Ionizing radiation in environment

International Nuclear Information System (INIS)

Jandl, J.; Petr, I.

1988-01-01

The basic terms are explained such as the atom, radioactivity, nuclear reaction, interaction of ionizing radiation with matter, etc. The basic dosimetric variables and units and properties of radionuclides and ionizing radiation are given. Natural and artificial sources of ionizing radiation are discussed with regard to the environment and the propagation and migration of radionuclides is described in the environment to man. The impact is explained of ionizing radiation on the cell and the somatic and genetic effects of radiation on man are outlined. Attention is devoted to protection against ionizing radiation and to radiation limits, also to the detection, dosimetry and monitoring of ionizing radiation in the environment. (M.D.). 92 figs., 40 tabs. 74 refs

Surface-ionization field mass-spectrometry studies of nonequilibrium surface ionization

International Nuclear Information System (INIS)

Blashenkov, Nikolai M; Lavrent'ev, Gennadii Ya

2007-01-01

The ionization of polyatomic molecules on tungsten and tungsten oxide surfaces is considered for quasiequilibrium or essentially nonequilibrium conditions (in the latter case, the term nonequilibrium surface ionization is used for adsorbate ionization). Heterogeneous reactions are supposed to proceed through monomolecular decay of polyatomic molecules or fragments of multimolecular complexes. The nonequilibrium nature of these reactions is established. The dependences of the current density of disordered ions on the surface temperature, electric field strength, and ionized particle energy distribution are obtained in analytical form. Heterogeneous dissociation energies, the ionization potentials of radicals, and the magnitude of reaction departure from equilibrium are determined from experimental data, as are energy exchange times between reaction products and surfaces, the number of molecules in molecular complexes, and the number of effective degrees of freedom in molecules and complexes. In collecting the data a new technique relying on surface-ionization field mass-spectrometry was applied. (instruments and methods of investigation)

Estimation of natural radiation background level and population dose in China

International Nuclear Information System (INIS)

Pan Ziqiang

1992-01-01

The authors describe in general the natural radiation background level in China, and based on available data present an estimated annual effective dose equivalent of the population to natural radiation that is some 2.3 mSv, of which about 0.54 mSv is from original γ radiation and about 0.8 mSv from radon and its short-lived daughters

The duration of reionization constrains the ionizing sources

Science.gov (United States)

Sharma, Mahavir; Theuns, Tom; Frenk, Carlos

2018-03-01

We investigate how the nature of the galaxies that reionized the Universe affects the duration of reionization. We contrast two sets of models: one in which galaxies on the faint side of the luminosity function dominate the ionizing emissivity, and a second in which the galaxies on the bright side of the luminosity function dominate. The faint-end of the luminosity function evolves slowly, therefore the transition from mostly neutral to mostly ionized state takes a much longer time in the first set of models compared to the second. Existing observational constraints on the duration of this transition are relatively weak, but taken at face value prefer the model in which galaxies on the bright side play a major role. Measurements of the kinetic Sunyaev Zeldovich effect in the cosmic microwave background from the epoch of reionization also point in the same direction.

The duration of reionization constrains the ionizing sources

Science.gov (United States)

Sharma, Mahavir; Theuns, Tom; Frenk, Carlos

2018-06-01

We investigate how the nature of the galaxies that reionized the Universe affects the duration of reionization. We contrast two sets of models: one in which galaxies on the faint side of the luminosity function dominate the ionizing emissivity, and a second in which the galaxies on the bright side of the luminosity function dominate. The faint end of the luminosity function evolves slowly, therefore the transition from mostly neutral to mostly ionized state takes a much longer time in the first set of models compared to the second. Existing observational constraints on the duration of this transition are relatively weak, but taken at face value prefer the model in which galaxies on the bright side play a major role. Measurements of the kinetic Sunyaev-Zeldovich effect in the cosmic microwave background from the epoch of reionization also point in the same direction.

Effects of the ionizing radiation in natural food colours

International Nuclear Information System (INIS)

Cosentino, Helio Morrone

2005-01-01

The world's fast growing population and its consequent increase in demand for food has driven mankind into improving technologies which ensure a safer supply of such commodities. Both food radiation processing and its constituents are highlighted as a feasible alternative technique capable of meeting food safety standards. Natural dyes are extensively employed in the food industry thanks to their colour enhancing properties on food products. This paper has aimed at studying the effects of ionizing radiation on three natural dyes: carminic acid and its derivatives (cochineal dyes), bixine and its salts (annatto dyes) and curcumin (turmeric dyes), used in the food and cosmetic industries within dilutions and doses those goods might eventually be processed in. It also envisages clarifying the compatibility of the irradiation technique with the keeping of such relevant sensorial attribute which is the product colour. Spectrophotometry and capillary electrophoresis were the analytic methods employed. All in all, a colour decrease proportional to the increase on the applied gamma radiation (1 to 32 kGy) has been observed. The annatto dyes have proven moderately stable whereas turmeric has shown to be highly sensitive to radiation. Those results shall be taken into account as far as the need to alter the formulae additive amount in the product is concerned whenever undergoing radiation processing. (author)

Monitoring of external background radiation level in Asa dam ...

African Journals Online (AJOL)

An external background ionizing radiation study has been carried out within the Asa Dam Industrial Layout of Ilorin in Kwara State. The study was carried out in 5 stations within the industrial area using two Digilert Nuclear Radiation Monitors. The study has revealed that the external background ionizing radiation is ...

Measurement of gamma natural background radiation at Chamaraja Nagar, Karnataka state, India

International Nuclear Information System (INIS)

Nagaraju, K.M.; Chandrashekara, M.S.; Paramesh, L.

2012-01-01

The radioactive elements and their radiation are ubiquitous in the environment. The Influence of radiation on living organisms is imminent and very important to study. The ocean, the mountains, the air, and our food all expose us to small amounts of natural background radiation. Cosmic rays from outer space are another large contributor of natural background radiation. Much of the earth's natural background radiation is in the form of gamma radiation, a part of which comes from outer space. Some part of cosmic ray is filtered out by the presence of earth's atmosphere, so there are natural controls for the amount of radiation that people receive. The amount of radiation received by an individual depends on altitude, latitude type of building and the building construction materials. In the present study, measurements of natural background radiation were made in the temples, schools, dwellings, and hill stations in Chamaraja Nagar area, Karnataka state, India by using environmental dosimeter technique. The results show that, absorbed dose rate of background radiations at inside schools varies from 93.96 to 120.93 nGyh -1 with a standard deviation of 10.62 nGyh -1 and outside schools it varies from 60.9 to 113.1 nGyh -1 with a standard deviation of 15.1 nGyh -1 . In temples, the absorbed dose rate varies from 104.4 to 244.91 nGyh - 1 with a standard deviation of 48.34 nGyh -1 and outside the temples it varies from 87.9 to 176.61 nGyh -1 with a standard deviation of 30.896 nGyh -1 . The absorbed dose rate of background radiations at dwellings in indoor varies from 94.0 to 139.2 nGyh -1 with a standard deviation of 16.6 nGyh -1 and in outdoor it varies from 60.9 to 118.32 nGyh -1 with a standard deviation of 19.41 nGyh -1 . The measurements were also carried out in dwellings on hill stations in Chamaraja Nagar district. Indoor gamma dose rate varies from 103.53 to 236.64 nGyh -1 with a standard deviation of 59.8 nGyh -1 and outdoor gamma dose rate varies from 78.3 to 119

On the ionization of interstellar magnesium

International Nuclear Information System (INIS)

Gurzadyan, G.A.

1977-01-01

It has been shown that two concentric ionization zones of interstellar magnesium must exist around each star: internal, with a radius coinciding with that of the zone of hydrogen ionization Ssub(H); and external, with a radius greater than Ssub(H), by one order. Unlike interstellar hydrogen, interstellar magnesium is ionized throughout the Galaxy. It also transpires that the ionizing radiation of ordinary hot stars cannot provide for the observed high degree of ionization of interstellar magnesium. The discrepance can be eliminated by assuming the existence of circumstellar clouds or additional ionization sources of interstellar magnesium (X-ray background radiation, high-energy particles, etc.). Stars of the B5 and BO class play the main role in the formation of ionization zones of interstellar magnesium; the contribution of O class stars is negligible (<1%). (Auth.)

Hybrid Simulation of Supersonic Flow of Weakly Ionized Plasma along Open Field Magnetic Line Effect of Background Pressure

Science.gov (United States)

Laosunthara, Ampan; Akatsuka, Hiroshi

2016-09-01

In previous study, we experimentally examined physical properties of supersonic flow of weakly ionized expanding arc-jet plasma through an open magnetic field line (Bmax 0.16T). We found supersonic velocity of helium plasma up to Mach 3 and the space potential drop at the end of the magnets. To understand the plasma in numerical point of view, the flows of ion and neutral are treated by particle-based Direct Simulation Monte Carlo (DSMC) method, electron is treated as a fluid. The previous numerical study, we assumed 2 conditions. Ion and electron temperatures were the same (LTE condition). Ion and electron velocities were the same (current-free condition). We found that ion velocity decreased by collision with residual gas molecules (background pressure). We also found that space potential changing with background pressure. In other words, it was indicated that electric field exists and the current-free assumption is not proper. In this study, we add electron continuity and electron momentum equations to obtain electron velocity and space potential. We find that space potential changing with background pressure slightly. It is indicated that electron is essential to space potential formation than ion.

Radiation levels at the boundaries of the Frascati center and natural background

International Nuclear Information System (INIS)

Lucci, F.; Pelliccioni, M.

1975-01-01

The results of dosimetric controls carried out with thermoluminescent dosimeters along the boundaries of the Frascati Center since 1969 are presented. The average yearly exposure observed during the period 1969-1974 is 206mR/y, while no significant tendency is evident. In particular neither effects of accelerator shutdowns nor seasonal ones are noticed. The measurements at the boundary are also compared with measurements of natural background carried out near Frascati and in Rome, Thus we can estimate that the machine contribution to the total dose along the boundaries is equal to a small fraction of either the natural background or the general population dose limit [fr

Paramecium aurelia as a cellular model used for studies of the biological effects of natural ionizing radiation or chronic low-level irradiation

International Nuclear Information System (INIS)

Planel, H.; Soleilhavoup, J.P.; Tixador, R.; Croute, F.; Richoilley, G.

1979-01-01

Paramecium aurelia appears to be a very suitable object for investigating the biological effects of natural ionizing radiation or the influence of low doses of radiation. The biological effects of ionizing radiation on cell proliferation kinetics were tested. It is shown that radio-protection or chronic exposure to very low doses of 60 Co gamma rays induce different changes in cell growth rate. Special experimental techniques can help to obtain more obvious results using cells more sensitive to the stimulating effects of low doses of ionizing radiation. (author)

Measures of association of some air pollutants. Natural ionizing radiation and cigarette smoking with mortality rates

Energy Technology Data Exchange (ETDEWEB)

Schwing, R C; McDonald, G C

1976-03-01

Two methods are employed to estimate the association of hydrocarbons, sulfur compounds, nitrogen compounds, natural ionizing radiation, and cigarette smoking with some age stratified and disease specific United States mortality rates for white males. The first method is based on a ridge regression technique and the second on a sign constrained least squares analysis. It is concluded that increased concentration of sulfur compounds and increased consumption of cigarettes are associated with increases in the total white male mortality rate. Associations for nitrogen compounds, the hydrogen index, and ionizing radiation are dependent on methodology and data stratification. The estimated elasticities are not directly comparable to those from other studies. Most estimates are fairly close except for the associations of heart disease with sulfur compounds. (JTE)

Natural background radiation induces cytogenetic radioadaptive response more effectively than occupational exposure in human peripheral blood lymphocytes

International Nuclear Information System (INIS)

Monfared, A.S.; Mozdarani, H.; Amiri, M.

2003-01-01

Ramsar, a city in the northern Iran, has the highest level of natural background radiation in the world. It has been clearly shown that low doses of ionising radiation can induce resistance to subsequent higher exposures. This phenomenon is termed radioadaptive response. We have compared induction of cytogenetic radioadaptive response by High Natural Background Radiation (HNBR) in Ramsar and X-ray occupational exposure as conditioning doses in human peripheral blood lymphocytes. 30 healthy control individuals, living in Ramsar but in normal background radiation areas, 15 healthy individuals from Talesh Mahalleh, a region with extraordinary high level of background radiation, and 7 X-ray radiographers working in Ramsar hospital located in normal natural background ionising radiation area were evaluated. Peripheral blood samples were prepared and exposed to challenge dose of 0 and 2 Gy. Lymphocytes were scored using analysis of metaphase, for the presence of chromosomal aberrations. An adaptive response was observed in HNBR and radiation workers groups in comparison with sham controls. A significant increase in adaptive response was observed in the HNBR group if compared with the occupationally exposed group. These findings indicate that both natural background radiation and occupational exposure could induce cytogenetic radioadaptive response and it is more significant regarding to natural background ionising radiation. (author)

Ghost peaks observed after atmospheric pressure matrix-assisted laser desorption/ionization experiments may disclose new ionization mechanism of matrix-assisted hypersonic velocity impact ionization.

Science.gov (United States)

Moskovets, Eugene

2015-08-30

Understanding the mechanisms of matrix-assisted laser desorption/ionization (MALDI) promises improvements in the sensitivity and specificity of many established applications in the field of mass spectrometry. This paper reports a serendipitous observation of a significant ion yield in a post-ionization experiment conducted after the sample had been removed from a standard atmospheric pressure (AP)-MALDI source. This post-ionization is interpreted in terms of collisions of microparticles moving with a hypersonic velocity into a solid surface. Calculations show that the thermal energy released during such collisions is close to that absorbed by the top matrix layer in traditional MALDI. The microparticles, containing both the matrix and analytes, could be detached from a film produced inside the inlet capillary during the sample ablation and accelerated by the flow rushing through the capillary. These observations contribute some new perspective to ion formation in both laser and laser-less matrix-assisted ionization. An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser had been turned off and the MALDI sample removed, ions were detected during a gradual reduction of the background pressure in the first funnel. The constant-rate pressure reduction led to the reproducible appearance of different singly and doubly charged peptide peaks in mass spectra taken a few seconds after the end of the MALDI analysis of a dried-droplet spot. The ion yield as well as the mass range of ions observed with a significant delay after a completion of the primary MALDI analysis depended primarily on the background pressure inside the first funnel. The production of ions in this post-ionization step was exclusively observed during the pressure drop. A lower matrix background and significant increase in relative yield of double-protonated ions are reported. The observations were partially consistent

MEASURING THE SOURCES OF THE INTERGALACTIC IONIZING FLUX

International Nuclear Information System (INIS)

Cowie, L. L.; Barger, A. J.; Trouille, L.

2009-01-01

We use a wide-field (0.9 deg 2 ) X-ray sample with optical and Galaxy Evolution Explorer (GALEX) ultraviolet observations to measure the contribution of active galactic nuclei (AGNs) to the ionizing flux as a function of redshift. Our analysis shows that the AGN contribution to the metagalactic ionizing background peaks at around z = 2. The measured values of the ionizing background from the AGNs are lower than previous estimates and confirm that ionization from AGNs is insufficient to maintain the observed ionization of the intergalactic medium (IGM) at z > 3. We show that only X-ray sources with broad lines in their optical spectra have detectable ionizing flux and that the ionizing flux seen in an AGN is not correlated with its X-ray color. We also use the GALEX observations of the GOODS-N region to place a 2σ upper limit of 0.008 on the average ionization fraction f ν (700 A)/f ν (1500 A) for 626 UV selected galaxies in the redshift range z = 0.9-1.4. We then use this limit to estimate an upper bound to the galaxy contribution in the redshift range z = 0-5. If the z ∼ 1.15 ionization fraction is appropriate for higher-redshift galaxies, then contributions from the galaxy population are also too low to account for the IGM ionization at the highest redshifts (z > 4).

Background current of radioisotope manometer

International Nuclear Information System (INIS)

Vydrik, A.A.

1987-01-01

The technique for calculating the main component of the background current of radioisotopic monometers, current from direct collision of ionizing particles and a collector, is described. The reasons for appearance of background photoelectron current are clarified. The most effective way of eliminating background current components is collector protection from the source by a screen made of material with a high gamma-quanta absorption coefficient, such as lead, for example

A novel natural environment background model for Monte Carlo simulation and its application in the simulation of anticoincidence measurement

International Nuclear Information System (INIS)

Li, Sangang; Wang, Lei; Cheng, Yi; Tuo, Xianguo; Liu, Mingzhe; Yao, Fuliang; Leng, Fengqing; Cheng, Yuanyuan; Cai, Ting; Zhou, Yan

2016-01-01

This study proposes a novel natural environment background model by modeling brief environment conditions. It uses Geant4 program to simulate decays of "2"3"8U, "2"3"2Th, and "4"0K in soil and obtains compositions of different-energy gamma rays in the natural environment background. The simulated gamma spectrum of the natural environment background agrees well with the experimental spectrum, particularly above 250 keV. The model is used in the simulation of anticoincidence measurement, indicating that the natural environment background can be decreased by approximately 88%, and the Compton attenuation factor is 2.22. The simulation of anticoincidence measurement can improve the minimum detectable activity (MDA) of the detection system. - Highlights: • This study proposes a novel natural environment background model by simulating decays of "2"3"8U, "2"3"2Th, and "4"0K in soil. • The simulated gamma spectrum of the natural environment background agrees well with the experimental spectrum, particularly above 250 keV. • The proposed environment background model is applied to study the properties of anticoincidence detector.

Display of charged ionizing particles

International Nuclear Information System (INIS)

Cano S, D.; Ortiz A, M. D.; Amarillas S, L. E.; Vega C, H. R.

2017-10-01

The human being is exposed to sources of ionizing and non-ionizing radiation, both of natural or anthropogenic origin. None of these, except non-ionizing such as visible light and infrared radiation, can be detected by the sense of sight and touch respectively. The sun emits charged particles with speeds close to the light that interact with the atoms of the gases present in the atmosphere, producing nuclear reactions that in turn produce other particles that reach the surface of the Earth and reach the living beings. On Earth there are natural radioisotopes that, when they disintegrate, emit ionizing radiation that contributes to the dose we receive. A very old system that allows the visualization of the trajectories of the charged ionizing particles is the Fog Chamber that uses a saturated steam that when crossed by particles with mass and charge, as alpha and beta particles produce condensation centers along its path leaves a trace that can be seen. The objective of this work was to build a fog chamber using easily accessible materials. To measure the functioning of the fog chamber, cosmic rays were measured, as well as a source of natural metal uranium. The fog chamber allowed seeing the presence of traces in alcohol vapor that are produced in a random way. Introducing the uranium foil inside the fog chamber, traces of alpha particles whose energy varies from 4 to 5 MeV were observed. (Author)

Effects of ionizing radiation upon natural populations and ecosystems. Final report

International Nuclear Information System (INIS)

McCormick, J.F.

1976-01-01

Accomplishments throughout a 10-year period summarized include: a study of the effects of radiation from a γ source on the ecology of the El Verde rain forest in Puerto Rico, with emphasis on the role of secondary succession in the recovery of forest ecosystems following irradiation; the effects of light and temperature on gaseous exchange in trees using 14 CO 2 as a tracer in Palcourea; the nature of the sensitivity of pine trees to ionizing radiation and the possible synergistic effects of elevated ozone levels on radiosensitivity; the combined effects of radioactive and thermal effluents on plant communities of a swamp hardwood forest; and the development of a new conceptual approach to the evaluation of environmental quality, with emphasis on ecological perspectives in land use planning

An intercomparison of detectors for measurement of background radiation

International Nuclear Information System (INIS)

Nielsen, S.P.; Boetter-Jensen, L.

1981-04-01

Measurements of the background radiation were made in 1978 at 14 locations with a high-pressure ionization chamber, thermoluminiscence dosimeters (TLD's), two NaI(Tl) detectors, and a Ge(Li) spectrometer system. Simultaneous measurements with the ionization chamber and the spectrometer system provide reliable estimates of the total background exposure rate, of the individual contributors to the terrestrial exposure rate, and of the exposure rate from the secondary cosmic radiation. The TLD results agree with those of the ionization chamber. The NaI(Tl) detector results show that accurate estimates of the terrestrial exposure rate can be obtained if empirical corrections are applied. (author)

PROPERTIES OF QSO METAL-LINE ABSORPTION SYSTEMS AT HIGH REDSHIFTS: NATURE AND EVOLUTION OF THE ABSORBERS AND NEW EVIDENCE ON ESCAPE OF IONIZING RADIATION FROM GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Boksenberg, Alec [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Sargent, Wallace L. W., E-mail: boksy@ast.cam.ac.uk [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2015-05-15

Using Voigt-profile-fitting procedures on Keck High Resolution Spectrograph spectra of nine QSOs, we identify 1099 C IV absorber components clumped in 201 systems outside the Lyman forest over 1.6 ≲ z ≲ 4.4. With associated Si IV, C II, Si II  and N V where available, we investigate the bulk statistical and ionization properties of the components and systems and find no significant change in redshift for C IV and Si IV while C II, Si II  and N V change substantially. The C IV components exhibit strong clustering, but no clustering is detected for systems on scales from 150 km s{sup –1} out to 50,000 km s{sup –1}. We conclude that the clustering is due entirely to the peculiar velocities of gas present in the circumgalactic media of galaxies. Using specific combinations of ionic ratios, we compare our observations with model ionization predictions for absorbers exposed to the metagalactic ionizing radiation background augmented by proximity radiation from their associated galaxies and find that the generally accepted means of radiative escape by transparent channels from the internal star-forming sites is spectrally not viable for our stronger absorbers. We develop an active scenario based on runaway stars with resulting changes in the efflux of radiation that naturally enable the needed spectral convergence, and in turn provide empirical indicators of morphological evolution in the associated galaxies. Together with a coexisting population of relatively compact galaxies indicated by the weaker absorbers in our sample, the collective escape of radiation is sufficient to maintain the intergalactic medium ionized over the full range 1.9 < z ≲ 4.4.

Effects of deprivation of background environmental radiation on cultured human cells

International Nuclear Information System (INIS)

Carbone, M.C.; Pinto, M.; Antonelli, F.; Balata, M.

2010-01-01

In this paper we present results from an experiment aimed at investigating whether living cells are influenced by background ionizing radiation. Parallel human cell cultures were set-up in two separate laboratories and maintained for several months under identical conditions but for a 80 x different level of background ionizing radiation. Periodically, the cell cultures were monitored for the onset of divergences in biochemical behavior, using two distinct cellular biology assays, namely micronuclei induction and activity of enzymes implicated in the management of oxidative stress. To reveal any subtle modifications, responses were also amplified by subjecting cell cultures to acute stress induced by exposure to moderately high doses of ionizing radiation. Compared to reference radiation background conditions, cultures maintained in a reduced background radiation environment handled the consequences of acute stress with diminished efficacy.

Past and present views in the approach to the problem of high natural background areas

International Nuclear Information System (INIS)

Mastino, G.G.

1982-01-01

High natural background areas are of great interest because they present anomalous conditions in their geological and geochemical features and consequently in the background radiation levels. High natural background areas have been recognised as representing a valid field of investigation for assessing the effects induced by low-level exposures. Such an approach represents the first attempt to draw an environmental impact evaluation, even if focussed on a single potentially harmful parameter only. Past and current studies on High Background Radiation Areas are reviewed with special emphasis on the ongoing programs and prospectives; their significance is discussed on the basis of the sectorial approach mostly used in the environmental studies. A more complete approach is suggested based on the impact evaluation and extention to all the potentially harmful environmental factors

What is ''ionizing radiation''?

International Nuclear Information System (INIS)

Tschurlovits, M.

1997-01-01

The scientific background of radiation protection and hence ''ionizing radiation'' is undergoing substantial regress since a century. Radiations as we are concerned with are from the beginning defined based upon their effects rather than upon the physical origin and their properties. This might be one of the reasons why the definition of the term ''ionizing radiation'' in radiation protection is still weak from an up to date point of view in texts as well as in international and national standards. The general meaning is unambiguous, but a numerical value depends on a number of conditions and the purpose. Hence, a clear statement on a numerical value of the energy threshold beyond a radiation has to be considered as ''ionizing'' is still missing. The existing definitions are, therefore, either correct but very general or theoretical and hence not applicable. This paper reviews existing definitions and suggests some issues to be taken into account for possible improvement of the definition of ''ionizing radiation''. (author)

Geographically determined dependencies in the value of the constant natural radiation gamma-background

International Nuclear Information System (INIS)

Miloslavov, V.

2001-01-01

The problem of the assessment of the influence of natural gamma background changes on the population is discussed. It is considered that the populations in different geographic regions have adapted by evolution mechanisms to the respective unchanged (without human activities) radiation background. The background limits for each area form the 'radiation comfortable zone' which varies very much for the different geographic areas. Leaving the 'comfortable zone' leads to a triggering of adaptive mechanisms in the population including the natural selection in order to reach an equilibrium. Thus, the radiation impact exceeding the 'comfortable zone' is expected to cause harm for a part of the population which is preliminarily burden or uncapable to adapt. From this point of view the increased morbidity due to radiation factor in those cases remains hidden. As a conclusion it is pointed out that the proposed increase of the annual dose for the population might result with harmful consequences for the whole human population

Comparison of selection methods to deduce natural background levels for groundwater units

NARCIS (Netherlands)

Griffioen, J.; Passier, H.F.; Klein, J.

2008-01-01

Establishment of natural background levels (NBL) for groundwater is commonly performed to serve as reference when assessing the contamination status of groundwater units. We compare various selection methods to establish NBLs using groundwater quality data forfour hydrogeologically different areas

Determination of exposure rates from natural background radiation in Khartoum using LiF:Mg,Cu,P (GR-200) and CaSo4: Mn TLD chips

International Nuclear Information System (INIS)

Suliman, I.I.; Khangi, F.A.; Shaddad, I.A.; Suliman, I.A.; El Amin, O.I.

2002-01-01

The exposure rates from natural background radiation - including terrestrial gamma radiation and the ionizing component of cosmic rays - were measured for the first time in the city of khartoum using two types of TLD materials: LiF:Mg,Cu,P (GR-200) and CaSo 4 :Mn TLD chips. Measurements were performed at two sites simultaneously, one site was selected on land in the vicinity of the Sudan Atomic Energy Commission, for the purposes of the measurement of the total exposure rate outdoors, while the other site was located on a buoy anchored in the Blue Nile, and was selected to measure the exposure rate due to the ionizing component of cosmic rays. The investigations were conducted for periods of between 5 and 28 days. Calibration was performed on a selected number of dosimeters to determine the exposure rates at each site. The exposure rates from the ionizing component of cosmic rays in Khartoum were found to be respectively 33 nGy.h -1 and 30 nGy.h -1 , in the measurements performed within the scope of this work using GR-200 and CaSo 4 :Mn dosimeters, while the total values for exposure on land were found to be 45 nGy.h -1 and 42 nGy.h -1 respectively. These values compare reasonably well with other national averages reported in the UNSCEAR publication. The comparison of the results for the two dosimetric materials demonstrates both the sensitivity and suitability of GR-200 for the purposes of environmental monitoring (orig.)

Ionizing and non-ionizing radiations

International Nuclear Information System (INIS)

1994-01-01

The monograph is a small manual to get a knowledge of ionizing and non-ionizing radiations. The main chapters are: - Electromagnetic radiations - Ionizing and non-ionizing radiations - Non-ionizing electromagnetic radiations - Ionizing electromagnetic radiation - Other ionizing radiations - Ionizing radiation effects - The Nuclear Safety Conseil

Information and energetic approaches to the influence of ionizing radiation on the organism

International Nuclear Information System (INIS)

Bulanova, K.Ya.; Lobanok, L.M.; Kundas, S.P.; Konoplya, E.F.

2005-01-01

In order to reveal the regularities of interaction of organism with low-intensive ionizing radiation, cybernetic approaches are needed. The living organisms are self-regulating system of a behavioural type. The complexity of the organization is determined by the hierarchy of controlling system. Relation between systems are not of physico-chemical nature; they are based on control, i.e. on information processes. In information system, all the weak influences (including ionizing radiation ) are perceived in the form of signal. Signal information of a natural radiation background is vitally important for organisms as in conversed type, as bioradiation, it is used for management initiation, i. e. self-regulation, self-development and so on. In the case of a superfluous surge of information at man-caused impacts of ionizing radiation (up to 10 Gr) the information system loses its ability to solve information tasks quickly and begins to experience the state of tension. Brought to a very tensed state it is able to lose its balance, its stability, i.e. to die. The signal-information perception of radiation explains the effects of its low dose, non-linear character of dependence of biologic response of irradiated dose, hormesis phenomenon, apoptosis, remote consequences of irradiation, bystander effect and other postradiation effects. (authors)

A novel natural environment background model for Monte Carlo simulation and its application in the simulation of anticoincidence measurement.

Science.gov (United States)

Li, Sangang; Wang, Lei; Cheng, Yi; Tuo, Xianguo; Liu, Mingzhe; Yao, Fuliang; Leng, Fengqing; Cheng, Yuanyuan; Cai, Ting; Zhou, Yan

2016-02-01

This study proposes a novel natural environment background model by modeling brief environment conditions. It uses Geant4 program to simulate decays of (238)U, (232)Th, and (40)K in soil and obtains compositions of different-energy gamma rays in the natural environment background. The simulated gamma spectrum of the natural environment background agrees well with the experimental spectrum, particularly above 250 keV. The model is used in the simulation of anticoincidence measurement, indicating that the natural environment background can be decreased by approximately 88%, and the Compton attenuation factor is 2.22. The simulation of anticoincidence measurement can improve the minimum detectable activity (MDA) of the detection system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Angular anisotropy of the cosmic microwave background radiation

International Nuclear Information System (INIS)

Silk, J.

1982-01-01

The theory of fluctuations in the cosmic microwave background radiation is reviewed. Anisotropy on large-scale (dipole and quadrupole) and on small scales is discussed. The smoothing effects of secondary ionization (fractional ionization x) are found to be unimportant over an angular scale greater than approx.= 5(OMEGAx)sup(1/3) degrees. (author)

Comparison of the ionizing radiation effects on cochineal, annatto and turmeric natural dyes

International Nuclear Information System (INIS)

Cosentino, Helio M.; Takinami, Patricia Y.I.; Mastro, Nelida L. del

2016-01-01

As studies on radiation stability of food dyes are scarce, commercially important natural food grade dyes were evaluated in terms of their sensitivity against gamma ionizing radiation. Cochineal, annatto and turmeric dyes with suitable concentrations were subjected to increasing doses up to 32 kGy and analyzed by spectrophotometry and capillary electrophoresis. The results showed different pattern of absorbance versus absorbed dose for the three systems. Carmine, the glucosidal coloring matter from the scale insect Coccus cacti L., Homoptera (cochineal) remained almost unaffected by radiation up to doses of about 32 kGy (absorbance at 494 nm). Meanwhile, at that dose, a plant-derived product annatto or urucum (Bixa orellana L.) tincture presented a nearly 58% reduction in color intensity. Tincture of curcumin (diferuloylmethane) the active ingredient in the eastern spice turmeric (Curcuma longa) showed to be highly sensitive to radiation when diluted. These data shall be taken in account whenever food products containing these food colors were going to undergo radiation processing. - Highlights: • Comparison of radiosensitivity of food colors was performed. • Carmine showed the highest resistance to radiation. • Annatto and turmeric behaved sensitive to radiation when diluted. • Turmeric was the most affected by ionizing radiation.

Distribution characteristics of natural gamma background levels around the capital city Shillong, Meghalaya (India)

International Nuclear Information System (INIS)

Kukreti, B.M.; Sharma, G.K.; Rao, M.S.; Ramabhadraih, T.; Bhaskar Rao, Arjun; Bhuphang, A.

2012-01-01

Onsite measurement of natural gamma radiation around the capital city Shillong in Meghalaya, has been carried out using GPS device and environmental survey meter. Each referenced insitu data point was validated at the site by means of simultaneous measurements of radiation levels (at 1.0 mts height) through handheld dosimeters. Collected data points on natural background levels, have been analysed and quantified in the context of preparing reference background levels in the city in order to deal with any radiological emergency that may arise in the public domain. Study reveals Gaussian distributed mean annual gamma dose of 0.77 mSv (n=53) in the range of 0.38 to 1.51 mSv. The study area, bound by the coordinates N (25.50°-25.66°, and E (91.82°-91.96°) indicates few pockets of higher average background levels, particularly towards the eastern side of study area, namely Nongmynsong, NEIGRIMS and Happy Valley. However, from the radiological safety aspects in public domain, all these reported levels are within the safety limits of prevailing environmental background. (author)

Measurement of the first ionization potential of astatine by laser ionization spectroscopy

Science.gov (United States)

Rothe, S.; Andreyev, A. N.; Antalic, S.; Borschevsky, A.; Capponi, L.; Cocolios, T. E.; De Witte, H.; Eliav, E.; Fedorov, D. V.; Fedosseev, V. N.; Fink, D. A.; Fritzsche, S.; Ghys, L.; Huyse, M.; Imai, N.; Kaldor, U.; Kudryavtsev, Yuri; Köster, U.; Lane, J. F. W.; Lassen, J.; Liberati, V.; Lynch, K. M.; Marsh, B. A.; Nishio, K.; Pauwels, D.; Pershina, V.; Popescu, L.; Procter, T. J.; Radulov, D.; Raeder, S.; Rajabali, M. M.; Rapisarda, E.; Rossel, R. E.; Sandhu, K.; Seliverstov, M. D.; Sjödin, A. M.; Van den Bergh, P.; Van Duppen, P.; Venhart, M.; Wakabayashi, Y.; Wendt, K. D. A.

2013-01-01

The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine. PMID:23673620

The Cryogenic Dark Matter Search and Background Rejection with Event Position Information

International Nuclear Information System (INIS)

Wang, Gen-sheng

2005-01-01

Evidence from observational cosmology and astrophysics indicates that about one third of the universe is matter, but that the known baryonic matter only contributes to the universe at 4%. A large fraction of the universe is cold and non-baryonic matter, which has important role in the universe structure formation and its evolution. The leading candidate for the non-baryonic dark matter is Weakly Interacting Massive Particles (WIMPs), which naturally occurs in the supersymmetry theory in particle physics. The Cryogenic Dark Matter Search (CDMS) experiment is searching for evidence of a WIMP interaction off an atomic nucleus in crystals of Ge and Si by measuring simultaneously the phonon energy and ionization energy of the interaction in the CDMS detectors. The WIMP interaction energy is from a few keV to tens of keV with a rate less than 0.1 events/kg/day. To reach the goal of WIMP detection, the CDMS experiment has been conducted in the Soudan mine with an active muon veto and multistage passive background shields. The CDMS detectors have a low energy threshold and background rejection capabilities based on ionization yield. However, betas from contamination and other radioactive sources produce surface interactions, which have low ionization yield, comparable to that of bulk nuclear interactions. The low-ionization surface electron recoils must be removed in the WIMP search data analysis. An emphasis of this thesis is on developing the method of the surface-interaction rejection using location information of the interactions, phonon energy distributions and phonon timing parameters. The result of the CDMS Soudan run118 92.3 live day WIMP search data analysis is presented, and represents the most sensitive search yet performed

The Cryogenic Dark Matter Search and Background Rejection with Event Position Information

Energy Technology Data Exchange (ETDEWEB)

Wang, Gensheng [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics

2005-01-01

Evidence from observational cosmology and astrophysics indicates that about one third of the universe is matter, but that the known baryonic matter only contributes to the universe at 4%. A large fraction of the universe is cold and non-baryonic matter, which has important role in the universe structure formation and its evolution. The leading candidate for the non-baryonic dark matter is Weakly Interacting Massive Particles (WIMPs), which naturally occurs in the supersymmetry theory in particle physics. The Cryogenic Dark Matter Search (CDMS) experiment is searching for evidence of a WIMP interaction off an atomic nucleus in crystals of Ge and Si by measuring simultaneously the phonon energy and ionization energy of the interaction in the CDMS detectors. The WIMP interaction energy is from a few keV to tens of keV with a rate less than 0.1 events/kg/day. To reach the goal of WIMP detection, the CDMS experiment has been conducted in the Soudan mine with an active muon veto and multistage passive background shields. The CDMS detectors have a low energy threshold and background rejection capabilities based on ionization yield. However, betas from contamination and other radioactive sources produce surface interactions, which have low ionization yield, comparable to that of bulk nuclear interactions. The low-ionization surface electron recoils must be removed in the WIMP search data analysis. An emphasis of this thesis is on developing the method of the surface-interaction rejection using location information of the interactions, phonon energy distributions and phonon timing parameters. The result of the CDMS Soudan run118 92.3 live day WIMP search data analysis is presented, and represents the most sensitive search yet performed.

III. Penning ionization, associative ionization and chemi-ionization processes

International Nuclear Information System (INIS)

Cermak, V.

1975-01-01

Physical mechanisms of three important ionization processes in a cold plasma and the methods of their experimental study are discussed. An apparatus for the investigation of the Penning ionization using ionization processes of long lived metastable rare gas atoms is described. Methods of determining interaction energies and ionization rates from the measured energy spectra of the originating electrons are described and illustrated by several examples. Typical associative ionization processes are listed and the ionization rates are compared with those of the Penning ionization. Interactions with short-lived excited particles and the transfer of excitation without ionization are discussed. (J.U.)

Liquid ionization chambers for LET determination

DEFF Research Database (Denmark)

Kaiser, Franz-Joachim; Bassler, Niels; Tölli, Heikki

Liquid ionization chambers [1] (LICs) have have been used in the last decades as background dosemeters. Since a few years LICs are also commercially available for dosimetry and are used for measurements of dose distributions where a high spatial distribution is necessary. Also in the last decades...... a differential equation applying several simplifications and approximations leading to discrepancies between theory and experiments [3]. The theory predicts the collection efficiency as a function of the electrical field and was applied for both air filled ionization chambers and liquid filled ionization...... chambers. For liquids the LET can be roughly deduced from the collection efficiency dependency on the electrical field inside a liquid ionization chambers [4] using an extrapolation method. We solved the fundamental differential equation again presented by Jaffe numerically, but now taking into account...

Effect of background radiation shielding on natural radioactivity distribution measurement with imaging plate

International Nuclear Information System (INIS)

Mori, C.; Suzuki, T.; Koido, S.; Uritani, A.; Miyahara, H.; Yanagida, K.; Miyahara, J.; Takahashi, K.

1996-01-01

Distribution images of natural radioactivity contained in various natural materials such as vegetable, animal meat and pottery work can be obtained with an imaging plate which has high sensitivity for nuclear radiations. For such very low levels of radioactivity, natural background radiations must be reduced using a shielding box. The lining, on the inside of the box, with low atomic number material such as acrylic resin is very effective in reducing electrons, β-rays and low energy X- and γ-rays emitted from the inner surface of the shielding material. Some images of natural radioactivity distribution were obtained and the radioactivity, mainly 40 K, contained in natural materials was measured by using an HPGe detector and also the imaging plate itself. (orig.)

Chemotaxonomic markers of organic, natural, and genetically modified soybeans detected by direct infusion electrospray ionization mass spectrometry

International Nuclear Information System (INIS)

Santos, L.S.; Catharino, R.R.; Eberlin, M.N.; Tsai, S.M.

2006-01-01

The crude methanolic extracts of a single bean from samples of organic, natural or genetically modified (GM) soybeans [Glycine max. (Merrill) L.] were analyzed by direct infusion electrospray ionization mass spectrometry (ESI-MS). These extracts, containing the most polar natural products of soybeans (free aglycones, monoglucosides, diglucosides and esters including isoflavones and flavones) provide characteristic fingerprinting mass spectra owing to different proportions or sets of components. Spectra distinctiveness is confirmed by chemometric multivariate analysis of the ESIMS data, which place the three-types of beans into well-defined groups. When ESI-MS is applied, these polar components constitute therefore unique chemotaxonomic markers able to provide fast soybean typification. (author)

Changes of ionizing radiation caused by natural radionuclides in the Curonian Spit

International Nuclear Information System (INIS)

Peciuliene, M.; Jasaitis, D.; Grigaliunaite-Vonseviciene, G. and others

2005-01-01

Taking into consideration a unique scenery of the Curonian Spit, dosimetric investigation of ionizing radiation caused by natural radionuclides is performed there. The influence of natural radionuclides present in the ground on the equivalent dose rate of gamma radiation in the ground surface air is established. Measurements of equivalent dose rate are carried out in the whole territory of the Curonian Spit in Lithuania. Especially numerous data have been collected on the coasts of the sea and bay, near them, in seaside dunes and by roads. The established equivalent dose rate values vary from 22 nSv/h (on the dune top) to 90 nSv/h (above an asphalt path). The values of the main gamma radiation source ( 40 K and 226 Ra) concentration are measured, and positive correlation of concentrations and equivalent dose rates in the ground surface air between 40 K and 2 '2 6 Ra is determinated. It is established that 40 K has the biggest influence on equivalent dose rate. The equivalent dose rate values in the ground surface air in the Curonian Spit are comparatively low (they can even be 1630 times lower in comparison to Guarapari beach, Brazil). (author)

Ionizing wave via high-power HF acceleration

OpenAIRE

Mishin, Evgeny; Pedersen, Todd

2010-01-01

Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60 km. This paper presents a physical model of an ionizing wavefront created by suprathermal electrons accelerated by the HF-excited plasma turbulence.

Toxicological evaluation of natural rubber latex film vulcanized with ionizing radiation

International Nuclear Information System (INIS)

Campos, Vania E.; Higa, Olga Z.; Guedes, Selma M.L.; Hanada, Seico

1999-01-01

The industrial vulcanization of natural rubber latex (NRL) is made worldwide by conventional process using sulphur, but it can be made by an alternative process using ionizing radiation. The main advantages of this process are related to absence of toxic effect promoted by chemical substances added to the NRL on the conventional process. In this research was tested the toxicological properties of the films vulcanized by the alternative process in relation to that vulcanized by the conventional process. The toxicity was evaluated by in vitro cytotoxicity assay and in vivo systemic toxicity assay. The results showed that vulcanized films by gamma ray are less cytotoxic. The systemic toxicity assay showed that only the vulcanized film using sulphur induced allaying and motor in coordination on the animals for a short period of time. these results evidence the less cytotoxic properties of vulcanized films by gamma ray in relation to that vulcanized by conventional process using sulphur. (author)

Use of natural diamonds to monitor 14C AMS instrument backgrounds

International Nuclear Information System (INIS)

Taylor, R.E.; Southon, John

2007-01-01

To examine one component of the instrument-based background in University of California Keck Carbon Cycle AMS spectrometer, we have obtained measurements on a set of natural diamonds pressed into sample holders. Natural diamond samples (N = 14) from different sources within rock formations with geological ages greatly in excess of 100 Ma yielded a range of currents (∼110-250 μA 12 C - where filamentous graphite typically yields ∼150 μA 12 C - ) and apparent 14 C ages (64.9 ± 0.4 ka BP [0.00031 ± 0.00002 fm] to 80.0 ± 1.1 ka BP [0.00005 ± 0.00001 fm]). Six fragments cut from a single diamond exhibited essentially identical 14 C values - 69.3 ± 0.5 ka-70.6 ± 0.5 ka BP. The oldest 14 C age equivalents were measured on natural diamonds which exhibited the highest current yields

Role of ionizing radiation in the natural history of the Earth

International Nuclear Information System (INIS)

Byakov, V.M.; Stepanov, S.V.; Stepanova, O.P.

2001-01-01

A role of ionizing radiation in some global processes and events in geological history of the Earth is considered. In particular, we discuss: (1) the influence of ionizing radiation from radioactive nuclei disseminated in sedimentary rocks on the transformation of terrestrial organic matter into stone coals and oil; (2) the effect of cosmic rays from Supernova stars as a common cause of quasi-regular global geological processes and biocatastrophes. (author)

High Frequency Propagation modeling in a disturbed background ionosphere: Results from the Metal Oxide Space Cloud (MOSC) experiment

Science.gov (United States)

Joshi, D. R.; Groves, K. M.

2015-12-01

The Air Force Research Laboratory (AFRL) launched two sounding rockets in the Kwajalein Atoll, Marshall Islands, in May 2013 known as the Metal Oxide Space Cloud (MOSC) experiment to study the interactions of artificial ionization and the background plasma. The rockets released samarium metal vapor in the lower F-region of the ionosphere that ionized forming a plasma cloud. A host of diagnostic instruments were used to probe and characterize the cloud including the ALTAIR incoherent scatter radar, multiple GPS and optical instruments, satellite radio beacons, and a dedicated network of high frequency (HF) radio links. Data from ALTAIR incoherent scatter radar and HF radio links have been analyzed to understand the impacts of the artificial ionization on radio wave propagation. During the first release the ionosphere was disturbed, rising rapidly and spread F formed within minutes after the release. To address the disturbed conditions present during the first release, we have developed a new method of assimilating oblique ionosonde data to generate the background ionosphere that can have numerous applications for HF systems. The link budget analysis of the received signals from the HF transmitters explains the missing low frequencies in the received signals along the great circle path. Observations and modeling confirm that the small amounts of ionized material injected in the lower-F region resulted in significant changes to the natural propagation environment.

Ionizing radiation sources. Ionizing radiation interaction with matter

International Nuclear Information System (INIS)

Popits, R.

1976-01-01

Fundamentals of nuclear physics are reviewed under the headings: obtaining of X-rays and their properties; modes of radioactive decay of natural or man-made radionuclides; radioactive neutron sources; nuclear fission as basis for devising nuclear reactors and weapons; thermonuclear reactions; cosmic radiation. Basic aspects of ionizing radiation interactions with matter are considered with regard to charged particles, photon radiation, and neutrons. (A.B.)

Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

Science.gov (United States)

Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

2011-01-01

-OTU level. Therefore, biofilm communities growing in sunlight exposed substrates are capable of coping with increased mutation rates and appear pre-adapted to levels of ionizing radiation in Chernobyl due to their natural adaptation to periodical desiccation and ambient UV radiation.

Ionizing radiation regulations and the dental practitioner: 1. The nature of ionizing radiation and its use in dentistry.

Science.gov (United States)

Rout, John; Brown, Jackie

2012-04-01

Legislation governing the use of ionizing radiation in the workplace and in medical treatment first became law in 1985 and 1988, being superseded by the Ionizing Radiations Regulations 1999 (IRR99) and the Ionizing Radiation (Medical Exposure) Regulations 2000, (IR(ME)R 2000), respectively. This legislation ensures a safe environment in which to work and receive treatment and requires that those involved in the radiographic process must be appropriately trained for the type of radiographic practice they perform. A list of the topics required is detailed in Schedule 2 of IR(ME)R 2000 and is paraphrased in Table 1, with the extent and amount of knowledge required depending on the type of radiographic practice undertaken. Virtually all dental practitioners undertake radiography as part of their clinical practice. Legislation requires that users of radiation, including dentists and members of the dental team, understand the basic principles of radiation physics, hazards and protection, and are able to undertake dental radiography safely with the production of high quality, diagnostic images.

Natural background radioactivity of the earth's surface -- essential information for environmental impact studies

International Nuclear Information System (INIS)

Tauchid, M.; Grasty, R.L.

2002-01-01

An environmental impact study is basically a study of change. This change is compared to the preexisting conditions that are usually perceived to be the original one or the 'pristine' stage. Unfortunately reliable information on the 'so called' pristine stage is far from adequate. One of the essential parts of this information is a good knowledge of the earth's chemical make up, or its geochemistry. Presently available data on the geochemistry of the earth's surface, including those related to radioactive elements, are incomplete and inconsistent. The main reason why a number of regulations are judged to be too strict and disproportional to the risks that might be caused by some human activities, is the lack of reliable information on the natural global geochemical background on which environmental regulations should be based. The main objective of this paper is to present a view on the need for complete baseline information on the earth's surface environment and in particular its geochemical character. It is only through the availability of complete information, including reliable baseline information on the natural radioactivity, that an appropriate study on the potential effect of the various naturally occurring elements on human health be carried out. Presented here are a number of examples where the natural radioactivity of an entire country has been mapped, or is in progress. Also described are the ways these undertakings were accomplished. There is a general misconception that elevated radioactivity can be found only around uranium mines, nuclear power reactors and similar nuclear installations. As can be seen from some of these maps, the natural background radioactivity of the earth's surface closely reflects the underlying geological formations and their alteration products. In reality, properly regulated and managed facilities, the levels of radioactivity associated with many of these facilities are generally quite low relative to those associated with

Ionizing Radiation and Human Gender Proportion at Birth: A Concise Review of the Literature and A Complementary Analysis of Historical and Recent Data

Directory of Open Access Journals (Sweden)

Eslami J.

2017-12-01

Full Text Available Dear Editor, This letter considers an article by Scherb et al. entitled “Ionizing radiation and the human gender proportion at birth: A concise review of the literature and a complementary analysis of historical and recent data” published in Early Human Development (DOI: http://dx.doi.org/10.1016/j.earlhumdev.2015.10.012 [1]. The authors of this challenging paper have reviewed the literature regarding the effect of exposure to ionizing radiation on gender ratio at birth. Scherb et al. have stated that above-thebackground levels of ionizing radiation may alter the gender ratio at birth: “We are of the strong opinion that gradually increasing the level of background radiation poses an increased genetic risk to humans and creature and that more research should be initiated in this respect. This has implications for the nuclear power industry, and emphasizes the importance of finding safe methods for processing and storing nuclear waste”. They also claimed that the data they presented confirm the existence of an impact of ionizing radiation on human secondary sex. This paper bears a very basic shortcoming. We know that at present, the level of natural background radiation varies on Earth at least two orders of magnitude [2]. Mortazavi et al. have previously published reports on the health effects of exposure to elevated levels of natural ionizing radiation in HBNRAs of Ramsar [2-6]. While radiation level in Ramsar is up to 260 mSv y−1 (the highest background radiation levels known among inhabited areas, up to 13 times higher than the recommended dose limit for radiation workers in Iran that is 20 mSv y−1, people living in high background radiation areas of Ramsar show no observable detrimental effect. It is worth mentioning that if a radiation dose of a few hundred mSv per year has adverse health effects and causes genetic abnormalities or an increased risk of cancer, it should be evident to the residents of these hot areas [6]. Moreover

Criteria for radiological protection against exposure to natural radiation

International Nuclear Information System (INIS)

Cardenas Herrera, Juan

2012-01-01

Exposure of humans to natural sources of radiation has been a continuous and inevitable feature of life on earth. This exposure exceeds all due to artificial sources combined for most people. Many exposures to natural radiation sources are modified by human action. In particular, natural radionuclides are released into the environment in mineral processing and in activities such as the production of phosphate fertilizers and the use of fossil fuels. An increase of exposures to this natural radiation is caused. The relevance of exposure to natural radiation is confirmed by the fact that, for most people, the exposures to natural background radiation have been much more significant than exposures to artificial sources, with exceptions. Among these exceptions have been noted: medical exposures, accidents with release of radionuclides and some specific workplaces. In all cases, however, the natural background radiation has formed the basis on which all the others exposures are added and is a common level serving as compared to other exposures. Regulations and instructions have begun to establish in some countries to regulate natural radiation, countries like Spain, have already incorporated into its regulations on health protection against ionizing radiation the subject of natural radiation. (author) [es

Acceleration of electrons and supplementary ionization during parametrical plasma heating

International Nuclear Information System (INIS)

Grach, S.M.; Mityakov, N.A.; Trakhtengerts, V.Yu.; AN SSSR, Gor'kij. Inst. Prikladnoj Fiziki)

1986-01-01

Acceleration of electrons by plasma waves in partially ionized plasma is considered with provision for the effects of turbulent scattering and formation of secondary electrons, which are produced in the process of electron shock ionization. It is shown that the avalanche density growth of electrons accelerated up to 1-2 ionization potential (instability) takes place beginning from some critical density of plasma waves. Density of fast electrons is found out along with plasma wave energy density at the stage of instability saturation. Additional concentration of a background plasma, which manifests itself due to ionization, is evaluated

Ghost peaks observed after AP-MALDI experiment may disclose new ionization mechanism of matrix assisted hypersonic velocity impact ionization

Science.gov (United States)

Moskovets, Eugene

2015-01-01

RATIONALE Understanding the mechanisms of MALDI promises improvements in the sensitivity and specificity of many established applications in the field of mass spectrometry. This paper reports a serendipitous observation of a significant ion yield in a post-ionization experiment conducted after the sample has been removed from a standard atmospheric pressure (AP)-MALDI source. This post-ionization is interpreted in terms of collisions of microparticles moving with a hypersonic velocity into a solid surface. Calculations show that the thermal energy released during such collisions is close to that absorbed by the top matrix layer in traditional MALDI. The microparticles, containing both the matrix and analytes, could be detached from a film produced inside the inlet capillary during the sample ablation and accelerated by the flow rushing through the capillary. These observations contribute some new perspective to ion formation in both laser and laserless matrix-assisted ionization. METHODS An AP-MALDI ion source hyphenated with a three-stage high-pressure ion funnel system was utilized for peptide mass analysis. After the laser was turned off and MALDI sample was removed, ions were detected during a gradual reduction of the background pressure in the first funnel. The constant-rate pressure reduction led to the reproducible appearance of different singly- and doubly-charged peptide peaks in mass spectra taken a few seconds after the end of the MALDI analysis of a dried-droplet spot. RESULTS The ion yield as well as the mass range of ions observed with a significant delay after a completion of the primary MALDI analysis depended primarily on the background pressure inside the first funnel. The production of ions in this post-ionization step was exclusively observed during the pressure drop. A lower matrix background and significant increase in relative yield of double-protonated ions are reported. CONCLUSIONS The observations were partially consistent with a model of

Assessment of Natural Exposure From Some kinds of Egyptian Gypsum Using Low Background Spectrometer

International Nuclear Information System (INIS)

Sroor, A.

2006-01-01

Radioactivity of natural gypsum and gypsum derived products are examined investigated due to their importance as element of building materials and agricultural gypsum. the natural gypsum and its product may constitute an additional source of radiation exposure to workers and members of public from radiation produced by radioactive decaying. thirty natural gypsum samples from different quarries and 32 fabricated gypsum samples from commercial companies were analyzed using low background HPGe detector. the natural concentration of Ra-226, 232 Th and 40 K activities in all samples were determined in Bq/Kg dry weight. it was found that radioactivity of natural gypsum is less than the fabricated gypsum, so it can be used as agricultural gypsum. fabricated gypsum is suitable for use as an element of building material in egypt

Exposure of the Bulgarian population from natural and manmade ionizing radiation sources in the mid 90-ies

International Nuclear Information System (INIS)

Vasilev, G.; Bajrakova, A.; Ingilizova, Kh.; Khristova, M.; Karadzhov, A.

1997-01-01

The main radiation sources the Bulgarian population is exposed to, e.g. natural radiation background and manmade exposure such as occupational, medical, nuclear power engineering and the like, are analyzed. The study covers the period 1991-1994 but it also contains a number of retrospective assessments concerning the last few decades. It is prepared with a special reference to the forthcoming report of the United Nations Scientific Committee on the effect of atomic radiation scheduled for publication in 1998/1999. The Bulgarian population exposure presented as average annual effective collective doses amounts to 20240 mSv/a from natural background, 6400 mSv/a from x-ray diagnostics, 400 mSv/a from nuclear medicine, 17 mSv/a from occupational exposure (uranium mining excluded) etc. Total exposure in excess to background irradiation is about 40% of the background one

Lightning rod ionizing natural ionca - Ionic electrode active trimetallictriac of grounding - Definitive and total solution against 'blackouts' and electrical faults generated by atmospheric charges (lightning)

Energy Technology Data Exchange (ETDEWEB)

Cabareda, Luis

2010-09-15

The Natural Ionizing System of Electrical Protection conformed by: Lightning Rod Ionizing Natural Ionca and Ionic Electrode Active Trimetallic Triac of Grounding offers Total Protection, Maximum Security and Zero Risk to Clinics, Hospitals, Integral Diagnostic Center, avoiding ''the burning'' of Electronics Cards; Refineries, Tanks and Stations of Fuel Provision; Electrical Substations, Towers and Transmission Lines with transformer protection, motors, elevators, A/C, mechanicals stairs, portable and cooling equipment, electrical plants, others. This New High Technology is the solution to the paradigm of Benjamin Franklin and it's the mechanism to end the 'Blackouts' that produces so many damages and losses throughout the world.

Interactive visual intervention planning in particle accelerator environments with ionizing radiation

CERN Document Server

Fabry, Thomas

Radiation is omnipresent. It has many interesting applications: in medicine, where it allows curing and diagnosing patients; in communication, where modern communication systems make use of electromagnetic radiation; and in science, where it is used to discover the structure of materials; to name a few. Physically, radiation is a process in which particles or waves travel through any kind of material, usually air. Radiation can be very energetic, in which case it can break the atoms of ordinary matter (ionization). If this is the case, radiation is called ionizing. It is known that ionizing radiation can be far more harmful to living beings than non-ionizing radiation. In this dissertation, we are concerned with ionizing radiation. Naturally occurring ionizing radiation in the form of radioactivity is a most natural phenomenon. Almost everything is radioactive: there is radiation emerging from the soil, it is in the air, and the whole planet is constantly undergoing streams of energetic cosmic radiation. Sinc...

Car-borne survey of natural background gamma dose rate in Canakkale region (Turkey)

International Nuclear Information System (INIS)

Turhan, S.; Arikan, I. H.; Oquz, F.; Aezdemir, T.; Yuecel, B.; Varinlioqlu, A.; Koese, A.

2012-01-01

Natural background gamma radiation was measured along roads in the environs of Canakkale region by using a car-borne spectrometer system with a plastic gamma radiation detector. In addition, activity concentrations of 238 U, 226 Ra, 232 Th and 40 K in soil samples from the Canakkale region were determined by using a gamma spectrometer with an HPGe detector. A total of 92 856 data of the background gamma dose rate were collected for the Canakkale region. The background gamma dose rate of the Canakkale region was mapped using ArcGIS software, applying the geostatistical inverse distance-weighted method. The average and population-weighted average of the gamma dose are 55.4 and 40.6 nGy h -1 , respectively. The corresponding average annual effective dose to the public ranged from 26.6 to 96.8 μSv. (authors)

38 CFR 3.311 - Claims based on exposure to ionizing radiation.

Science.gov (United States)

2010-07-01

... to ionizing radiation. 3.311 Section 3.311 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF... Evaluations; Service Connection § 3.311 Claims based on exposure to ionizing radiation. (a) Determinations of... to ionizing radiation in service, an assessment will be made as to the size and nature of the...

Ionizing radiation and cancer prevention

International Nuclear Information System (INIS)

Hoel, D.G.

1995-01-01

Ionizing radiation long has been recognized as a cause of cancer. Among environmental cancer risks, radiation in unique in the variety of organs and tissues that it can affect. Numerous epidemiological studies with good dosimetry provide the basis for cancer risk estimation, including quantitative information derived from observed dose-response relationships. The amount of cancer attributable to ionizing radiation is difficult to estimate, but numbers such as 1 to 3% have been suggested. Some radiation-induced cancers attributable to ionizing radiation is difficult to estimate, but numbers such as 1 to 3% have been suggested. Some radiation-induced cancers attributable to naturally occurring exposures, such as cosmic and terrestrial radiation, are not preventable. The major natural radiation exposure, radon, can often be reduced, especially in the home, but not entirely eliminated. Medical use of radiation constitutes the other main category of exposure, radon, can often be reduced, especially in the home, but not entirely eliminated. Medical use of radiation constitutes the other main category of exposure; because of the importance of its benefits to one's health, the appropriate prevention strategy is to simply work to minimize exposures. 9 refs., 1 fig., 5 tabs

Measurement of the natural radiation background level of Riyadh City

International Nuclear Information System (INIS)

Al-Kusayer, T.A.; Al-Haj, A.N.

1987-01-01

A gamma spectroscopy system was used to analyze the radionuclides in soil samples and to determine the cumulative radioactivity of terrestrial origin in the Riyadh City area. Minimal work has been done in the 1980s to measure the natural background radiation level in Saudi Arabia by using thermoluminescent dosimeters. The measurement of the natural radioactivity in the Riyadh area for the radionuclide concentration in becquerels per kilogram, the exposure rate arising from radionuclides in grays per hour, and the equivalent dose rate in sieverts per hour are the goals of this work. Soil samples were collected from 21 places in Riyadh City. Each site was sampled for two depth profiles, 0 to 5 cm and 5 to 15 cm. These measurements were taken before the Chernobyl accident, and in the absence of any measurements for that area in the past, this work can be considered in future work for a reference 137 Cs concentration in Riyadh soil to determine the 137 Cs increase in the soil after the Chernobyl accident

Chemical protection against ionizing radiation. Final report

International Nuclear Information System (INIS)

Livesey, J.C.; Reed, D.J.; Adamson, L.F.

1984-08-01

The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references

Chemical protection against ionizing radiation. Final report

Energy Technology Data Exchange (ETDEWEB)

Livesey, J.C.; Reed, D.J.; Adamson, L.F.

1984-08-01

The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references.

Natural inflation: consistency with cosmic microwave background observations of Planck and BICEP2

International Nuclear Information System (INIS)

Freese, Katherine; Kinney, William H.

2015-01-01

Natural inflation is a good fit to all cosmic microwave background (CMB) data and may be the correct description of an early inflationary expansion of the Universe. The large angular scale CMB polarization experiment BICEP2 has announced a major discovery, which can be explained as the gravitational wave signature of inflation, at a level that matches predictions by natural inflation models. The natural inflation (NI) potential is theoretically exceptionally well motivated in that it is naturally flat due to shift symmetries, and in the simplest version takes the form V(φ) = Λ 4  [1 ± cos(Nφ/f)]. A tensor-to-scalar ratio r > 0.1 as seen by BICEP2 requires the height of any inflationary potential to be comparable to the scale of grand unification and the width to be comparable to the Planck scale. The Cosine Natural Inflation model agrees with all cosmic microwave background measurements as long as f ≥ m Pl (where m Pl  = 1.22 × 10 19  GeV) and Λ ∼ m GUT  ∼ 10 16  GeV. This paper also discusses other variants of the natural inflation scenario: we show that axion monodromy with potential V∝ φ 2/3 is inconsistent with the BICEP2 limits at the 95% confidence level, and low-scale inflation is strongly ruled out. Linear potentials V ∝ φ are inconsistent with the BICEP2 limit at the 95% confidence level, but are marginally consistent with a joint Planck/BICEP2 limit at 95%. We discuss the pseudo-Nambu Goldstone model proposed by Kinney and Mahanthappa as a concrete realization of low-scale inflation. While the low-scale limit of the model is inconsistent with the data, the large-field limit of the model is marginally consistent with BICEP2. All of the models considered predict negligible running of the scalar spectral index, and would be ruled out by a detection of running

Fitness costs of increased cataract frequency and cumulative radiation dose in natural mammalian populations from Chernobyl.

Science.gov (United States)

Lehmann, Philipp; Boratyński, Zbyszek; Mappes, Tapio; Mousseau, Timothy A; Møller, Anders P

2016-01-27

A cataract is a clouding of the lens that reduces light transmission to the retina, and it decreases the visual acuity of the bearer. The prevalence of cataracts in natural populations of mammals, and their potential ecological significance, is poorly known. Cataracts have been reported to arise from high levels of oxidative stress and a major cause of oxidative stress is ionizing radiation. We investigated whether elevated frequencies of cataracts are found in eyes of bank voles Myodes glareolus collected from natural populations in areas with varying levels of background radiation in Chernobyl. We found high frequencies of cataracts in voles collected from different areas in Chernobyl. The frequency of cataracts was positively correlated with age, and in females also with the accumulated radiation dose. Furthermore, the number of offspring in female voles was negatively correlated with cataract severity. The results suggest that cataracts primarily develop as a function of ionizing background radiation, most likely as a plastic response to high levels of oxidative stress. It is therefore possible that the elevated levels of background radiation in Chernobyl affect the ecology and fitness of local mammals both directly through, for instance, reduced fertility and indirectly, through increased cataractogenesis.

The Cryogenic Dark Matter Search: First 5-Tower Data and Improved Understanding of Ionization Collection

Energy Technology Data Exchange (ETDEWEB)

Bailey, Catherine N. [Case Western Reserve Univ., Cleveland, OH (United States)

2010-01-01

The Cryogenic Dark Matter Search (CDMS) is searching for Weakly Interacting Massive Particles (WIMPs) with cryogenic particle detectors. These detectors have the ability to discriminate between nuclear recoil candidate and electron recoil background events by collecting both phonon and ionization energy from recoils in the detector crystals. The CDMS-II experiment has completed analysis of the first data runs with 30 semiconductor detectors at the Soudan Underground Laboratory, resulting in a world leading WIMP-nucleon spin-independent cross section limit for WIMP masses above 44 GeV/c². As CDMS aims to achieve greater WIMP sensitivity, it is necessary to increase the detector mass and discrimination between signal and background events. Incomplete ionization collection results in the largest background in the CDMS detectors as this causes electron recoil background interactions to appear as false candidate events. Two primary causes of incomplete ionization collection are surface and bulk trapping. Recent work has been focused on reducing surface trapping through the modification of fabrication methods for future detectors. Analyzing data taken with test devices has shown that hydrogen passivation of the amorphous silicon blocking layer worsens surface trapping. Additional data has shown that the iron-ion implantation used to lower the critical temperature of the tungsten transition-edge sensors causes a degradation of the ionization collection. Using selective implantation on future detectors may improve ionization collection for events near the phonon side detector surface. Bulk trapping is minimized by neutralizing ionized lattice impurities. Detector investigations at testing facilities and in situ at the experimental site have provided methods to optimize the neutralization process and monitor running conditions to maintain full ionization collection. This work details my contribution to the 5-tower data taking, monitoring, and analysis effort as

Single-photon double ionization: renormalized-natural-orbital theory versus multi-configurational Hartree–Fock

International Nuclear Information System (INIS)

Brics, M; Rapp, J; Bauer, D

2017-01-01

The N -particle wavefunction has too many dimensions for a direct time propagation of a many-body system according to the time-dependent Schrödinger equation (TDSE). On the other hand, time-dependent density functional theory (TDDFT) tells us that the single-particle density is, in principle, sufficient. However, a practicable equation of motion for the accurate time evolution of the single-particle density is unknown. It is thus an obvious idea to propagate a quantity which is not as reduced as the single-particle density but less dimensional than the N -body wavefunction. Recently, we have introduced time-dependent renormalized-natural-orbital theory (TDRNOT). TDRNOT is based on the propagation of the eigenfunctions of the one-body reduced density matrix, the so-called natural orbitals. In this paper we demonstrate how TDRNOT is related to the multi-configurational time-dependent Hartree–Fock (MCTDHF) approach. We also compare the performance of MCTDHF and TDRNOT versus the TDSE for single-photon double ionization (SPDI) of a 1D helium model atom. SPDI is one of the effects where TDDFT does not work in practice, especially if one is interested in correlated photoelectron spectra, for which no explicit density functional is known. (paper)

Environmental Ionizing Radiation Survey of Quarry Sites in Ilorin ...

African Journals Online (AJOL)

NJABS

Besides, human exposure to radiations may increase if they live in areas with radiation doses above normal background value. Hence, this study involves the determination of background ionizing radiation levels around quarry sites in the industrial area of Ilorin with a view to assessing whether the radiation level is within ...

Ionizing radiation changes the electronic properties of melanin and enhances the growth of melanized fungi.

Science.gov (United States)

Dadachova, Ekaterina; Bryan, Ruth A; Huang, Xianchun; Moadel, Tiffany; Schweitzer, Andrew D; Aisen, Philip; Nosanchuk, Joshua D; Casadevall, Arturo

2007-05-23

Melanin pigments are ubiquitous in nature. Melanized microorganisms are often the dominating species in certain extreme environments, such as soils contaminated with radionuclides, suggesting that the presence of melanin is beneficial in their life cycle. We hypothesized that ionizing radiation could change the electronic properties of melanin and might enhance the growth of melanized microorganisms. Ionizing irradiation changed the electron spin resonance (ESR) signal of melanin, consistent with changes in electronic structure. Irradiated melanin manifested a 4-fold increase in its capacity to reduce NADH relative to non-irradiated melanin. HPLC analysis of melanin from fungi grown on different substrates revealed chemical complexity, dependence of melanin composition on the growth substrate and possible influence of melanin composition on its interaction with ionizing radiation. XTT/MTT assays showed increased metabolic activity of melanized C. neoformans cells relative to non-melanized cells, and exposure to ionizing radiation enhanced the electron-transfer properties of melanin in melanized cells. Melanized Wangiella dermatitidis and Cryptococcus neoformans cells exposed to ionizing radiation approximately 500 times higher than background grew significantly faster as indicated by higher CFUs, more dry weight biomass and 3-fold greater incorporation of (14)C-acetate than non-irradiated melanized cells or irradiated albino mutants. In addition, radiation enhanced the growth of melanized Cladosporium sphaerospermum cells under limited nutrients conditions. Exposure of melanin to ionizing radiation, and possibly other forms of electromagnetic radiation, changes its electronic properties. Melanized fungal cells manifested increased growth relative to non-melanized cells after exposure to ionizing radiation, raising intriguing questions about a potential role for melanin in energy capture and utilization.

Estimation of effective dose to public from external exposure to natural background radiation in saudi arabia

International Nuclear Information System (INIS)

Khalid, A. A.

2003-01-01

The effective dose values in sixteen cities in Saudi Arabia due to external exposure to natural radiation were evaluated. These doses are based on natural background components including external exposure to terrestrial radiation and cosmic rays. The importance of evaluating the effective dose to the public due to external exposure to natural background radiation lies in its epidemiological and dosimetric importance and in forming a basis for the assessment of the level of radioactive contamination or pollution in the environment in the future. The exposure to terrestrial radiation was measured using thermoluminescent dosimeters (TLD). The exposure from cosmic radiation was determined using empirical correlation. The values evaluated for the total annual effective dose in all cities were within the world average values. The highest total annual effective dose measured in Al-Khamis city was 802 μSv/y, as compared to 305 μSv/y in Dammam city, which was considered the lowest value

Natural radioactivity in the Dutch outdoor environment. The explanation of uncomprehended variations in the background

International Nuclear Information System (INIS)

Blaauboer, R.O.; Smetsers, R.C.G.M.

1996-01-01

In the Netherlands and many other countries research in the field of natural radioactivity is focused on the prevention of radon in the indoor environment. However, also the occurrence of natural radioactivity in the outdoor environment is an interesting subject to be studied. The natural background radiation in the outdoor environment, in particular its variations, hinders the verification of radiation level standards, caused by human activities. An analysis of the data of the Dutch National Monitoring Network for Radioactivity (LMR) provided more insight into those variations. This article is a summary of the authors' thesis on the subject. 5 figs., 8 refs

Early reionization by decaying particles and cosmic microwave background radiation

International Nuclear Information System (INIS)

Kasuya, S.; Kawasaki, M.

2004-01-01

We study the reionization scenario in which ionizing UV photons emitted from decaying particle, in addition to usual contributions from stars and quasars, ionize the universe. It is found that the scenario is consistent with both the first year data of the Wilkinson Microwave Anisotropy Probe and the fact that the universe is not fully ionized until z∼6 as observed by Sloan Digital Sky Survey. Likelihood analysis revealed that rather broad parameter space can be chosen. This scenario will be discriminated by future observations, especially by the EE polarization power spectrum of cosmic microwave background radiation

HYPERION NET - a distributed measurement system for monitoring background ionizing radiation

International Nuclear Information System (INIS)

Saponjic, Dj.; Zigic, A.; Arandjelovic, V.

2003-01-01

The distributed measurement system - HYPERION NET, based on the concept of FieldBus technology, has been developed, implemented, and tested as a pilot project, the first WEB enabled on-line networked ionizing radiation monitoring and measurement system. The Net has layered the structure, tree topology, and is based on the Internet infrastructure and TCP/IP communication protocol. The Net's core element is an intelligent GM transmitter, based on GM tube, used for measuring the absorbed dose in air, in the range of 0.087 to 720 μGy/h. The transmitter makes use of an advanced count rate measurement algorithm capable of suppressing the statistical fluctuations of the measured quantity, which significantly improves its measurement performance mailing it suitable for environmental radiation measurements. (author)

Comparison of the ionizing radiation effects on cochineal, annatto and turmeric natural dyes

Science.gov (United States)

Cosentino, Helio M.; Takinami, Patricia Y. I.; del Mastro, Nelida L.

2016-07-01

As studies on radiation stability of food dyes are scarce, commercially important natural food grade dyes were evaluated in terms of their sensitivity against gamma ionizing radiation. Cochineal, annatto and turmeric dyes with suitable concentrations were subjected to increasing doses up to 32 kGy and analyzed by spectrophotometry and capillary electrophoresis. The results showed different pattern of absorbance versus absorbed dose for the three systems. Carmine, the glucosidal coloring matter from the scale insect Coccus cacti L., Homoptera (cochineal) remained almost unaffected by radiation up to doses of about 32 kGy (absorbance at 494 nm). Meanwhile, at that dose, a plant-derived product annatto or urucum (Bixa orellana L.) tincture presented a nearly 58% reduction in color intensity. Tincture of curcumin (diferuloylmethane) the active ingredient in the eastern spice turmeric (Curcuma longa) showed to be highly sensitive to radiation when diluted. These data shall be taken in account whenever food products containing these food colors were going to undergo radiation processing.

On the nature of low-energy background in instruments for rentgenoradiometric analysis

International Nuclear Information System (INIS)

Kokhov, E.D.; Mamikonyan, S.V.; Mel'ttser, L.V.; Mil'chakov, V.I.; Shchekin, K.I.

1972-01-01

A study of the background radiation nature and its attenuation are one of the main techniques to decrease the sensitivity threshold of a roentgen radiometric analysis. The reasons for low-energy ''tail'' occurence are investigated in the article. It has been concluded that the low-energy ''tail'' occurence within the energy range less than 25 keV depends on a proportional counter. It has been confirmed that one of the main reasons for the low-energy ''tail'' occurence lies in photoelectron leakage from the counter sensing volume. It is shown that while determining the concentrations close to the sensitivity threshold, the elimination of radiation of the sample incident on the counter surface at an inclination angle seems to be reasonable. The test results show that the use of a collimator makes it possible to decrease the background concentration or the sensitivity threshold about 1.5 times as much

Cancer occurrence in the high natural background radiation area of Kerala coast

International Nuclear Information System (INIS)

Krishnan Nair, M.; Sreedevi Amma, N.; Ramachandran, T.P.; Varghese Cherian; Jayalakshmy, P.; Mani, K.S.; Boban, T.G.; Jayadevan, S.; Gangadharan, P.

1994-01-01

In order to assess the health effects if any, in populations living in high background radiation areas, the Department of Atomic Energy has sanctioned a 5-year project to establish a Registry covering Karunagappally taluk. The study proposes to cover a population of about 1,00,000 persons living in high background radiation areas where the radiation levels range anywhere between 10 and 825 μR/h inside the houses; for comparison the study proposes to cover another 3,00,000 persons living in nearby normal areas where the natural radiation levels range between 6 and 200 μ R/h. The data collected so far in the first 2.5 years are presented in this paper which covers a population of about 1,10,000 persons living in three villages. No attempt is made to interpret the data at this preliminary stage. (author). 7 tabs

Means of evaluation of population dose from the natural background of radiation for control of the exposure of environment of nuclear power plants

International Nuclear Information System (INIS)

Pensko, J.

1974-01-01

Given in this paper are the method and the results of calculation of the average value of the equivalent of the dose of the natural background of radiation, affecting the gonads and the bone marrow of the inhabitants of one of the regions of Poland, chosen as an example. These values weighed on a number of more important environmental factors, amounts to 78.0 mrem/years for gonads and 72.1 mrem/year for bone marrow. The value of the total population dose for the investigated region, from these sources of radiation, does not exceed 1.2 x 10 4 man-rem/year. Calculations were performed mainly on the base of the results of measurements of the exposure dose rate by a scintillation monitor from aboard an airplane, using also the numerous measurements of the dose at the height of 1 m over the earth's surface, done by means of a high-pressure ionization chamber, and the results of gamma spectrometric analysis of samples of soil. In calculations, coefficients of transformation of the exposure dose into the dose absorbed by various tissues, and the time spent indoors, were taken into consideration. For this purpose, using a proper coefficient of building screen has been suggested. This method can be used for estimating the average population dose, from the external radiation originating from natural and artificial radioactive sources, present in the environment of nuclear power plants. (author)

Natural and man-made terrestrial electromagnetic noise: an outlook

Directory of Open Access Journals (Sweden)

A. Meloni

2007-06-01

Full Text Available The terrestrial environment is continuously exposed to electromagnetic radiations which set up a «background» electromagnetic noise. Within the Non Ionizing Radiation band (NIR, i.e. for frequencies lower than 300 GHz, this background can have a natural or an artificial origin. Natural origins of electromagnetic radiations are generally atmospheric or cosmic while artificial origins are technological applications, power transmission, communications, etc. This paper briefly describes the natural and man-made electromagnetic noise in the NIR band. Natural noise comes from a large variety of sources involving different physical phenomena and covering a wide range of frequencies and showing various propagation characteristics with an extremely broad range of power levels. Due to technological growth man-made electromagnetic noise is nowadays superimposed on natural noise almost everywhere on Earth. In the last decades man-made noise has increased dramatically over and above the natural noise in residential and business areas. This increase has led some scientists to consider possible negative effects of electromagnetic waves on human life and living systems in general. Accurate measurements of natural and man-made electromagnetic noise are necessary to understand the relative power levels in the different bands and their influence on life.

Development of standard ionization chamber counting system for activity measurements

International Nuclear Information System (INIS)

Pyun, Woong Beom; Lee, Hyun Koo; Lee, Hai Yong; Park, Tae Soon

1998-01-01

This study is to set up the activity measuring system using a 4π γ ionization chamber as used mainly in national standards laboratories that are responsible for radionuclide metrology. The software for automatic control between the electrometer and personal computer is developed using Microsoft visual basic 4.0 and IEEE488 Interface. The reproducibility of this 4π γ ionization chamber is about 0.02% and the background current is 0.054±0.024 pA. this 4π γ ionization chamber is calibrated by 6 standard gamma emitting radionuclides from KRISS. According to the result of this study, it is revealed that this 4π γ ionization chamber counting system can be used as a secondary standard instrument for radioactivity measurement

Development of standard ionization chamber counting system for activity measurements

CERN Document Server

Pyun, W B; Lee, H Y; Park, T S

1998-01-01

This study is to set up the activity measuring system using a 4 pi gamma ionization chamber as used mainly in national standards laboratories that are responsible for radionuclide metrology. The software for automatic control between the electrometer and personal computer is developed using Microsoft visual basic 4.0 and IEEE488 Interface. The reproducibility of this 4 pi gamma ionization chamber is about 0.02% and the background current is 0.054+-0.024 pA. this 4 pi gamma ionization chamber is calibrated by 6 standard gamma emitting radionuclides from KRISS. According to the result of this study, it is revealed that this 4 pi gamma ionization chamber counting system can be used as a secondary standard instrument for radioactivity measurement.

A dark matter detector based on the simultaneous measurement of phonons and ionization at 20 mK

Energy Technology Data Exchange (ETDEWEB)

Shutt, Thomas Alan [UC, Berkeley

1993-01-01

One of the most important issues in astrophysics and cosmology is understanding the nature of dark matter. One possibility is that it is made of weakly interacting subatomic particles created in the big bang, such as the lightest particle in supersymmetry models. These particles should scatter elastically of nuclei in a detector on earth at a rate of ~events/kg/week, and will deposit energies of a few keV. Current attempts to detect these interactions are limited by a radioactive background of photons and beta particles which scatter on electrons. We have developed a novel particle detector to look for dark matter based on the simultaneous measurement of ionization and phonons in a 60 g crystal of high purity germanium at a temperature of 20 mK. Background events can be distinguished by our detector because they produce more ionization per unit phonon energy than dark matter interactions. The phonon energy is measured as a temperature change in the detector by means of neutron transmutation doped germanium thermistors attached to the crystal. The ionization measurement is accomplished by applying a bias to implanted contacts on the faces of the disk. Charge collection differs from the normal situation at 77 K in that no thermally generated free charge exists in the crystal at 20 mK. The collection efficiency is good with an electric field of only ~0.2 V/cm after the charged impurities in the crystal have been neutralized by free charge created by particle interactions from a radioactive source. For fields below this charge collection is poor, and affects the amount of phonon energy measured. We have modeled this in terms of charge trapping. The r.m.s resolution of the detector is 800 eV in phonons and 600 eV in ionization. We have tested the background rejection capability of the detector by exposing it to neutrons from a 251Cf source which scatter elastically on nuclei. The neutrons are distinguished at energies of a few keV, and the current background rejection

Origin of irradiations by ionizing radiations

International Nuclear Information System (INIS)

Metivier, H.

1998-01-01

Irradiations by ionizing radiations proceed from two main sources: the natural radiations from the environment and the sources of 'human' origin, i.e. linked with modern technology. In most countries the irradiation by natural sources remains the most important. The irradiations for medical purposes comes in second position and depends on the degree of technological evolution of the country, and in the last position are the irradiations linked with nuclear industry. The inventory of these irradiations is regularly updated by the Scientific Committee of the United Nations for the study of ionizing radiation effects (UNSCEAR). In France the mean individual irradiation due to natural radioactivity is of 2 mSv per year of efficient dose and can vary with a factor 3 from one region to the other. Irradiation of medical diagnosis origin is of about 1 mSv per year. This paper presents successively: the natural irradiation sources (cosmic radiation, cosmic rays and cosmogenic radionuclides, the Earth's radiations, primary radionuclides and radon), the natural sources modified by the technology (extraction industries, fossil fuels and phosphated ores, aerial transports and space activities, consumer products), the irradiation sources of technological origin (nuclear weapons, electric power production, major accidents, occupational irradiations), and the medical irradiations (diagnosis techniques, radiology, nuclear medicine and therapeutic uses). (J.S.)

Information approach to the assessment of mechanisms and action consequences of ionizing radiation in low doses on a living organism

International Nuclear Information System (INIS)

Bulanova, K.Ya.; Kundas, S.P.; Lobanok, L.M.; Konoplya, E.F.

2006-01-01

In order to reveal the regularities of interaction of the organism with low-intense ionizing radiation, cybernetic approaches are needed. Living organisms are a self-regulating system of behavioural type. The complexity of the organization is determined by the hierarchy of a controlling system. Relations between systems are not of physico-chemical nature; they are based on control, i. e. on information processes. In the information system, all the weak influences (including ionizing radiation) are perceived in the form of a signal. Signal information of a natural radiation background is vitally important for organisms as in cardioversion type, as bioradiation, it is used for management initiation, i. e. self-regulation, self-development and so on. In the case of a superfluous surge of information at man-caused impacts of ionizing radiation (up to 10 Gy) the information system loses its ability to solve information tasks quickly and begins to experience the state of tension. Brought to a very tensed state it is able to lose its balance, its stability, i. e. to die. The signal-information perception of radiation explains the effects of its low dose, the non-linear character of dependence of biologic response of irradiated dose, hormesis phenomenon, apoptosis, remote consequences of irradiation, bystander effect and other postradiation effects. (authors)

Display of charged ionizing particles; Visualizacion de particulas cargadas ionizantes

Energy Technology Data Exchange (ETDEWEB)

Cano S, D.; Ortiz A, M. D.; Amarillas S, L. E.; Vega C, H. R., E-mail: qfbcano@gmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico)

2017-10-15

The human being is exposed to sources of ionizing and non-ionizing radiation, both of natural or anthropogenic origin. None of these, except non-ionizing such as visible light and infrared radiation, can be detected by the sense of sight and touch respectively. The sun emits charged particles with speeds close to the light that interact with the atoms of the gases present in the atmosphere, producing nuclear reactions that in turn produce other particles that reach the surface of the Earth and reach the living beings. On Earth there are natural radioisotopes that, when they disintegrate, emit ionizing radiation that contributes to the dose we receive. A very old system that allows the visualization of the trajectories of the charged ionizing particles is the Fog Chamber that uses a saturated steam that when crossed by particles with mass and charge, as alpha and beta particles produce condensation centers along its path leaves a trace that can be seen. The objective of this work was to build a fog chamber using easily accessible materials. To measure the functioning of the fog chamber, cosmic rays were measured, as well as a source of natural metal uranium. The fog chamber allowed seeing the presence of traces in alcohol vapor that are produced in a random way. Introducing the uranium foil inside the fog chamber, traces of alpha particles whose energy varies from 4 to 5 MeV were observed. (Author)

Hanford Site background: Part 1, Soil background for nonradioactive analytes

International Nuclear Information System (INIS)

1993-04-01

The determination of soil background is one of the most important activities supporting environmental restoration and waste management on the Hanford Site. Background compositions serve as the basis for identifying soil contamination, and also as a baseline in risk assessment processes used to determine soil cleanup and treatment levels. These uses of soil background require an understanding of the extent to which analytes of concern occur naturally in the soils. This report documents the results of sampling and analysis activities designed to characterize the composition of soil background at the Hanford Site, and to evaluate the feasibility for use as Sitewide background. The compositions of naturally occurring soils in the vadose Zone have been-determined for-nonradioactive inorganic and organic analytes and related physical properties. These results confirm that a Sitewide approach to the characterization of soil background is technically sound and is a viable alternative to the determination and use of numerous local or area backgrounds that yield inconsistent definitions of contamination. Sitewide soil background consists of several types of data and is appropriate for use in identifying contamination in all soils in the vadose zone on the Hanford Site. The natural concentrations of nearly every inorganic analyte extend to levels that exceed calculated health-based cleanup limits. The levels of most inorganic analytes, however, are well below these health-based limits. The highest measured background concentrations occur in three volumetrically minor soil types, the most important of which are topsoils adjacent to the Columbia River that are rich in organic carbon. No organic analyte levels above detection were found in any of the soil samples

Effects of intravenous administration of two volumes of calcium solution on plasma ionized calcium concentration and recovery from naturally occurring hypocalcemia in lactating dairy cows.

NARCIS (Netherlands)

Doze, J.G.; Donders, R.; Kolk, J.H. van der

2008-01-01

OBJECTIVE: To compare the effects of administration of 2 volumes of a calcium solution (calcium oxide and calcium gluconate) on plasma ionized calcium concentration (PICaC) and clinical recovery from naturally occurring hypocalcemia (NOHC; milk fever) in lactating dairy cows. ANIMALS: 123 cows with

Critical assessment of ionization patterns and applications of ambient desorption/ionization mass spectrometry using FAPA-MS.

Science.gov (United States)

Brüggemann, Martin; Karu, Einar; Hoffmann, Thorsten

2016-02-01

Ambient desorption/ionization mass spectrometry (MS) has gained growing interest during the last decade due to its high analytical performance and yet simplicity. Here, one of the recently developed ambient desorption/ionization MS sources, the flowing atmospheric-pressure afterglow (FAPA) source, was investigated in detail regarding background ions and typical ionization patterns in the positive as well as the negative ion mode for a variety of compound classes, comprising alkanes, alcohols, aldehydes, ketones, carboxylic acids, organic peroxides and alkaloids. A broad range of signals for adducts and losses was found, besides the usually emphasized detection of quasimolecular ions, i.e. [M + H](+) and [M - H](-) in the positive and the negative mode, respectively. It was found that FAPA-MS is best suited for polar analytes containing nitrogen and/or oxygen functionalities, e.g. carboxylic acids, with low molecular weights and relatively high vapor pressures. In addition, the source was used in proof-of-principle studies, illustrating the capabilities and limitations of the technique: Firstly, traces of cocaine were detected and unambiguously identified on euro banknotes using FAPA ionization in combination with tandem MS, suggesting a correlation between cocaine abundance and age of the banknote. Secondly, FAPA-MS was used for the identification of acidic marker compounds in organic aerosol samples, indicating yet-undiscovered matrix and sample surface effects of ionization pathways in the afterglow region. Copyright © 2016 John Wiley & Sons, Ltd.

Ionizing radiation induces tumor cell lysyl oxidase secretion

DEFF Research Database (Denmark)

Shen, Colette J; Sharma, Ashish; Vuong, Dinh-Van

2014-01-01

BACKGROUND: Ionizing radiation (IR) is a mainstay of cancer therapy, but irradiation can at times also lead to stress responses, which counteract IR-induced cytotoxicity. IR also triggers cellular secretion of vascular endothelial growth factor, transforming growth factor beta and matrix...

Role of natural radiation environment in earth sciences

International Nuclear Information System (INIS)

Vohra, K.G.

1980-01-01

Natural ionizing radiations play an important role in a wide spectrum of earth sciences, including meteorology, geophysics, hydrology, atmospheric physics, and atmospheric chemistry. The nature and distribution of ionizing radiation sources and natural radionuclides in the atmospheric environment are summarized. The present status of the use of natural radioactive tracers for atmospheric studies is discussed. The effect of ionization produced by natural radiation sources on atmospheric electricity, the relationship of electrical and meteorological variables, and the possible effects of man-made releases of 85 Kr are considered. Experimental evidence is presented for the production of condensation nuclei by the combined effects of radon and sulfur dioxide

Ionization chamber smoke detectors

International Nuclear Information System (INIS)

1988-03-01

One kind of smoke detector, the ionization-type, is regulated by the Atomic Energy Control Board (AECB) because it uses a radioactive substance in its mechanism. Radioactivity and radiation are natural phenomena, but they are not very familiar to the average householder. This has led to a number of questions being asked of the AECB. These questions and AECB responses are outlined

Exploring Redox Properties of Aromatic Amino Acids in Water: Contrasting Single Photon vs Resonant Multiphoton Ionization in Aqueous Solutions.

Science.gov (United States)

Roy, Anirban; Seidel, Robert; Kumar, Gaurav; Bradforth, Stephen E

2018-04-12

Direct measurements of the valence ionization energies and the reorganization energies of the three aromatic amino acids, l-tyrosine, l-tryptophan, and l-phenylalanine, in aqueous solution using the liquid microjet technique and two different photoemission methods-X-ray photoelectron spectroscopy (XPS) at 175 eV photon energy and resonant two-photon ionization (R2PI) using 2 × 267 nm (2 × 4.64 eV) UV laser light-are reported. l-Tryptophan has the lowest vertical ionization energy, 7.3 eV, followed by tyrosine (7.8 eV) and phenylalanine (∼8.7 eV). Essentially, no variation in recovered orbital energies is observed comparing near threshold ionization to X-ray ionization. Superior sensitivity of the (background-free) R2PI scheme for solutions with very low solute concentration (<2 mM) is demonstrated in contrast to the single-photon XPS measurements, which often requires solute concentrations of 0.1-1 molar. This higher sensitivity along with chemical selectivity of the R2PI technique can be exploited for both spectroscopic assignment and as an analytical tool. The nature of the adiabatic ionization energy for the three aromatic amino acids has been explored by the R2PI approach and by empirically formulating the correlation between the estimated ionization onset with electronic and nuclear relaxation on the excited state surface. Our results have implications for understanding one-electron transfer within enzymes and in redox situations where (ir)reversible deprotonation occurs such as those manifest in the biochemistry of oxidation damage.

Effect of increased ionization on the atmospheric electric field

International Nuclear Information System (INIS)

Boeck, W.L.

1980-01-01

This study is a review of atmospheric electrical theory with the purpose of predicting the atmospheric electrical effects of increased ionization caused by radioactive inert gases. A time-independent perturbation model for the global atmospheric electric circuit precdicts that the electric field at the sea surface would be reduced to about 76% of its unperturbed value by a surface 85 Kr concentration of 3 nCi/m 3 . The electric field at a typical land station is predicted to be about 84% of its unperturbed value. Some scientists have suggested that the atmospheric electric field is part of a closed electrical feedback loop. The present model does not include such a closed feedback loop and may underestimate the total effects. This model is also useful for interpreting atmospheric electrical responses to natural fluctuations in the cosmic-ray component of background radiation

Statistical methods for determination of background levels for naturally occuring radionuclides in soil at a RCRA facility

International Nuclear Information System (INIS)

Guha, S.; Taylor, J.H.

1996-01-01

It is critical that summary statistics on background data, or background levels, be computed based on standardized and defensible statistical methods because background levels are frequently used in subsequent analyses and comparisons performed by separate analysts over time. The final background for naturally occurring radionuclide concentrations in soil at a RCRA facility, and the associated statistical methods used to estimate these concentrations, are presented. The primary objective is to describe, via a case study, the statistical methods used to estimate 95% upper tolerance limits (UTL) on radionuclide background soil data sets. A 95% UTL on background samples can be used as a screening level concentration in the absence of definitive soil cleanup criteria for naturally occurring radionuclides. The statistical methods are based exclusively on EPA guidance. This paper includes an introduction, a discussion of the analytical results for the radionuclides and a detailed description of the statistical analyses leading to the determination of 95% UTLs. Soil concentrations reported are based on validated data. Data sets are categorized as surficial soil; samples collected at depths from zero to one-half foot; and deep soil, samples collected from 3 to 5 feet. These data sets were tested for statistical outliers and underlying distributions were determined by using the chi-squared test for goodness-of-fit. UTLs for the data sets were then computed based on the percentage of non-detects and the appropriate best-fit distribution (lognormal, normal, or non-parametric). For data sets containing greater than approximately 50% nondetects, nonparametric UTLs were computed

Review Ionizing Radiation In The Environment

International Nuclear Information System (INIS)

Hassan, K.M.

2007-01-01

Our environment is pervaded by ionizing radiation of natural origin including terrestrial radionuclides and extra-terrestrial sources but man's activities can increase radiation levels by acting on natural sources or by producing artificial radionuclides. The energy released by radionuclides can be measured. The amount of energy generated in our bodies from the radioactive decay of within- body radionuclides is called internal dose. External dose results from gamma rays emitted by terrestrial sources such as the ground, building materials and from extraterrestrial sources. The major contributors to human exposure are radon and its daughters in the air that we breathe. Ionizing radiation can penetrate into matter and thus, causing damage by interacting with the atoms and molecules of the medium. If the medium is living tissue, damage to cells can take place. Very large doses of radiation will result in serious tissue, damage that may lead to death of the organism. Lower doses may also be harmful and do not cause the immediate damage of high doses but instead act to increase the likelihood of developing cancer. So, exposure to ionizing radiation can have health consequences, which is why we are concerned about and, to a large extent, is why this review paper was written. Exposure to ionizing radiation should be kept as minimum as practically possible. People are advised to monitor the concentrations of radon in their houses. In addition, the levels of radionuclides in drinking water should also be monitored in accordance with the guidelines used in the USA

Ionizing radiation interactions with DNA: nanodosimetry

International Nuclear Information System (INIS)

Bug, Marion; Nettelbeck, Heidi; Hilgers, Gerhard; Rabus, Hans

2011-01-01

The metrology of ionizing radiation is based on measuring values that are averaged over macroscopic volume elements, for instance the energy dose is defined as ratio of the energy deposited on the absorber and the absorber mass. For biological or medical radiation effects the stochastic nature of radiation interaction id of main importance, esp. the interaction of ionizing radiation with the DNA as the genetic information carrier. For radiotherapy and risk evaluation purposes a comprehensive system of radiation weighing factors and other characteristics, like radiation quality or relative biological efficacy was developed. The nanodosimetry is aimed to develop a metrological basis relying on physical characteristics of the microscopic structure of ionizing radiation tracks. The article includes the development of experimental nanodosimetric methods, the respective calibration techniques, Monte-Carlo simulation of the particle track microstructure and the correlation nanodosimetry and biological efficiency.

Effects of ionizing radiation on cryogenic infrared detectors

Science.gov (United States)

Moseley, S. H.; Silverberg, R. F.; Lakew, B.

1989-01-01

The Diffuse Infrared Background Experiment (DIRBE) is one of three experiments to be carried aboard the Cosmic Background Explorer (COBE) satellite scheduled to be launched by NASA on a Delta rocket in 1989. The DIRBE is a cryogenic absolute photometer operating in a liquid helium dewar at 1.5 K. Photometric stability is a principal requirement for achieving the scientific objectives of this experiment. The Infrared Astronomy Satellite (IRAS), launched in 1983, which used detectors similar to those in DIRBE, revealed substantial changes in detector responsivity following exposure to ionizing radiation encountered on passage through the South Atlantic Anomaly (SAA). Since the COBE will use the same 900 Km sun-synchronous orbit as IRAS, ionizing radiation-induced performance changes in the detectors were a major concern. Here, ionizing radiation tests carried out on all the DIRBE photodetectors are reported. Responsivity changes following exposure to gamma rays, protons, and alpha particle are discussed. The detector performance was monitored following a simulated entire mission life dose. In addition, the response of the detectors to individual particle interactions was measured. The InSb photovoltaic detectors and the Blocked Impurity Band (BIB) detectors revealed no significant change in responsivity following radiation exposure. The Ge:Ga detectors show large effects which were greatly reduced by proper thermal annealing.

Nature of the ionizing source of the nuclear gas in NGC 1052

International Nuclear Information System (INIS)

Keel, W.C.; Miller, J.S.

1983-01-01

We examine the ionization and physical state of the emission-line region in the nucleus of elliptical galaxy NGC 1052. The [O III] lambda4363/lambda5007 ratio, frequently used as a diagnostic for ionization mechanisms, is very poorly determined because of difficulties in matching the underlying stellar continuum spectrum, which is unusual in having very strong lines for the galaxy luminosity. Within these limitations, we find the [O III] temperature to be only marginally compatible with shock models, and the overall emission spectrum to be better fitted by photoionization models with a very dilute flat-spectrum central source. In any event, the case for NGC 1052 as a shock-heated nucleus is not strong

Effects of low doses of ionizing radiation

International Nuclear Information System (INIS)

Anon.

2008-01-01

Ionizing radiation of cosmic or terrestrial origin is part of the environment in which all living things have evolved since the creation of the universe. The artificial radioactivity generated by medical diagnostic and treatment techniques, some industrial activities, radioactive fallout, etc. has now been added to this natural radioactivity. This article reviews the biological effects of the low doses of ionizing radiation to which the population is thus exposed. Their carcinogenic risk cannot simply be extrapolated from what we know about high-dose exposure. (author)

Genetic variation in resistance to ionizing radiation

International Nuclear Information System (INIS)

Ayala, F.J.

1991-01-01

We proposed an investigation of genetically-determined individual differences in sensitivity to ionizing radiation. The model organism is Drosophila melanogaster. The gene coding for Cu,Zn superoxide dismutase (SOD) is the target locus, but the effects of variation in other components of the genome that modulate SOD levels are also taken into account. SOD scavenges oxygen radicals generated during exposure to ionizing radiation. It has been shown to protect against ionizing radiation damage to DNA, viruses, bacteria, mammalian cells, whole mice, and Drosophila. Two alleles, S and F, are commonly found in natural populations of D. melanogaster; in addition we have isolated from a natural population ''null'' (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide an ideal model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CA1. The roles of SOD level in radioresistance are being investigated in a series of experiments that measure the somatic and germ-line effects of increasing doses of ionizing radiation. In addition, we have pursued an unexpected genetic event-namely the nearly simultaneous transformation of several lines homozygous for the SOD ''null'' allele into predominately S lines. Using specifically designed probes and DNA amplification by means of the Tag polymerase chain reaction (PCR) we have shown that (1) the null allele was still present in the transformed lines, but was being gradually replaced by the S allele as a consequence of natural selection; and (2) that the transformation was due to the spontaneous deletion of a 0.68 Kb truncated P-element, the insertion of which is characteristic of the CA1 null allele

Metrology of ionizing radiations and environmental measurements

International Nuclear Information System (INIS)

Nourreddine, Abdel-Mjid

2008-01-01

The subject of radiation protection covers all measurements taken by the authorities to ensure protection of the population and its environment against the harmful effects of ionizing radiation. Dosimetry occupies an important place in this field, because it makes it possible to consider and to quantify the risk of using radiations in accordance with the prescribed limits. In this course, we will review the fundamental concepts used in the metrology and dosimetry of ionizing radiations. After classification of ionizing radiations according to their interactions with biological matter, we will present the various quantities and units brought into play and in particular the new operational quantities that are good estimators raising protection standards. They are directly connected to the annual limits of effective dose and of equivalent dose defined in the French regulation relating to the protection of the population and of workers against ionizing radiations. The average natural exposure of the population in France varies between 2 to 2.5 mSv per year, depending on geographic location. It comes principally from three sources: cosmic radiation, radioactive elements contained in the ground and radioactive elements that we absorb when breathing or eating. Radon, which is a naturally occurring radioactive gas, is a public health risk and represents 30% of the exposure. Finally, we will give some applications of dosimetry and environmental measurements developed recently at RaMsEs/IPHC laboratory of Strasbourg. (author)

Health effects of ionizing radiation

International Nuclear Information System (INIS)

Radford, E.P.

1980-01-01

This presentation is restricted to the health effects of low doses of ionizing radiation. In general, these cumulative exposures are well below 100 rem, or about 50 times background or less. The two effects of interest in this dose range are genetic mutations and cancer production. The genetic effects will not be discussed in detail. The chief reason for the rise in risk estimates for cancer is the longer follow-up of exposed populations

The situation of knowledge on ionizing radiation

International Nuclear Information System (INIS)

2005-01-01

Occupational exposure to ionizing radiation occurs: during sources use, during the use of matter including radioactivity used for other properties than their radioactivity, in presence of natural radioactivity on the working area, following an accident during an industrial process. to protect man taken into account the incurred risk, goes by the risk evaluation, in taking into account the industrial process and exposure conditions of persons, then by the application of prevention measures that aim to control the contamination risks by radioactive matters as well as the exposure risks to ionizing radiations. (N.C.)

Collinear Resonance Ionization Spectroscopy of Neutron-Deficient Francium Isotopes

CERN Document Server

Flanagan, K T; Ruiz, R F Garcia; Budincevic, I; Procter, T J; Fedosseev, V N; Lynch, K M; Cocolios, T E; Marsh, B A; Neyens, G; Strashnov, I; Stroke, H H; Rossel, R E; Heylen, H; Billowes, J; Rothe, S; Bissell, M L; Wendt, K D A; de Groote, R P; De Schepper, S

2013-01-01

The magnetic moments and isotope shifts of the neutron-deficient francium isotopes Fr202-205 were measured at ISOLDE-CERN with use of collinear resonance ionization spectroscopy. A production-to-detection efficiency of 1\\% was measured for Fr-202. The background from nonresonant and collisional ionization was maintained below one ion in 10(5) beam particles. Through a comparison of the measured charge radii with predictions from the spherical droplet model, it is concluded that the ground-state wave function remains spherical down to Fr-205, with a departure observed in Fr-203 (N = 116).

Formation of molecules in interstellar clouds from singly and multiply ionized atoms

International Nuclear Information System (INIS)

Langer, W.D.; and NASA, Institute for Space Studies, Goddard Space Flight Center, New York)

1978-01-01

Soft X-ray and cosmic rays produce multiply ionized atoms which may initiate molecule production in interstellar clouds. This molecule production can occur via ion-molecule reactions with H 2 , either directly from the multiply ionized atom (e.g.,C ++ + H 2 →CH + + H + ), or indirectly from the singly ionized atoms (e.g., N + + H 2 →NH + + H) that are formed from the recombination or charge transfer of the highly ionized atom (e.g., N ++ + e→N + + hv). We investigate the contribution of these reactions to the abundances of carbon-, nitrogen-, and oxygen-bearing molecules in isobaric models of diffuse clouds. In the presence of the average flux estimated for the diffuse soft X-ray background, multiply ionized atoms contribute only minimally (a few percent) to carbon-bearing molecules such as CH. In the neighborhood of diffuse structures or discrete sources, however, where the X-ray flux is enhanced, multiple ionization is considerably more important for molecule production

Properties of Natural Radiation and Radioactivity

International Nuclear Information System (INIS)

Strom, Daniel J.

2009-01-01

Ubiquitous natural sources of radiation and radioactive material (naturally occurring radioactive material, NORM) have exposed humans throughout history. To these natural sources have been added technologically-enhanced naturally occurring radioactive material (TENORM) sources and human-made (anthropogenic) sources. This chapter describes the ubiquitous radiation sources that we call background, including primordial radionuclides such as 40K, 87Rb, the 232Th series, the 238U series, and the 235U series; cosmogenic radionuclides such as 3H and 14C; anthropogenic radionuclides such as 3H, 14C, 137Cs, 90Sr, and 129I; radiation from space; and radiation from technologically-enhanced concentrations of natural radionuclides, particularly the short-lived decay products of 222Rn ('radon') and 220Rn ('thoron') in indoor air. These sources produce radiation doses to people principally via external irradiation or internal irradiation following intakes by inhalation or ingestion. The effective doses from each are given, with a total of 3.11 mSv y-1 (311 mrem y-1) to the average US resident. Over 2.5 million US residents receive over 20 mSv y-1 (2 rem y-1), primarily due to indoor radon. Exposure to radiation from NORM and TENORM produces the largest fraction of ubiquitous background exposure to US residents, on the order of 2.78 mSv (278 mrem) or about 89%. This is roughly 45% of the average annual effective dose to a US resident of 6.2 mSv y-1 (620 mrem y-1) that includes medical (48%), consumer products and air travel (2%), and occupational and industrial (0.1%). Much of this chapter is based on National Council on Radiation Protection and Measurements (NCRP) Report No. 160, 'Ionizing Radiation Exposure of the Population of the United States,' for which the author chaired the subcommittee that wrote Chapter 3 on 'Ubiquitous Background Radiation.'

A magnetically levitated electrode ionization chamber of the noncontact measurement type

International Nuclear Information System (INIS)

Kawaguchi, Toshiro; Yoshimura, Atsushi

2002-01-01

A new type of ionization chamber with levitated electrode has been developed. In this ionization chamber, an ion-collection electrode levitates in the air without getting any physical support from the insulator. The electrode is charged by an electrostatic charger without physical contact. The charge of the electrode is read out at a Faraday cage periodically at a given time interval without physical contact. Because its electrode levitates, the ionization chamber produces no background current caused by leaks or piezo current. In addition, as the charging of its electrode and the read-out of its charge are carried out without physical contact, no irregular charge or contact potential difference due to the chattering between electrode and contact point occurs. Through experiments, it was found that this ionization chamber was able to measure the γ-ray dose such as the environmental radiation with a high degree of sensitivity. The minimum detectable value of ionization current when accumulated for 1 h is about 1.3x10 -17 A

A magnetically levitated electrode ionization chamber of the noncontact measurement type

CERN Document Server

Kawaguchi, T

2002-01-01

A new type of ionization chamber with levitated electrode has been developed. In this ionization chamber, an ion-collection electrode levitates in the air without getting any physical support from the insulator. The electrode is charged by an electrostatic charger without physical contact. The charge of the electrode is read out at a Faraday cage periodically at a given time interval without physical contact. Because its electrode levitates, the ionization chamber produces no background current caused by leaks or piezo current. In addition, as the charging of its electrode and the read-out of its charge are carried out without physical contact, no irregular charge or contact potential difference due to the chattering between electrode and contact point occurs. Through experiments, it was found that this ionization chamber was able to measure the gamma-ray dose such as the environmental radiation with a high degree of sensitivity. The minimum detectable value of ionization current when accumulated for 1 h is a...

Inner shell ionization by incident nuclei

International Nuclear Information System (INIS)

Hansteen, J.M.

1974-10-01

The atomic Coulomb excitation process induced by impinging heavy charged particles such as protons, deuterons, α-particles and complex heavy ions is reviewed. Recent experimental and theoretical efforts have led toimproved understanding of the atomic Coulomb excitation as well as to discovery of new types of ionization mechanisms. The following models are mentioned: the Plane Wave Born Approximation (PWBA); theeeeeeeeeeeee modified PWBA model; the Binary Encounter Approximation (BEA); the Semi-Classical Approximation (SCA); the Perturbed-Stationary-State model (PSS). The structure of the SCA model is more thoroughly treated. Experimental results on single Coulomb ionizations of the K-, L-, and M-shells, and of the connected sub-shells by protons are compared with predictions. Most calculations are based on straight line projectile paths and non-relativistic hydrogen-like target electron wave functions. The BEA model and the SCA model seem to work reasonably well for multiple Coulomb ionizations by stripped light ions. Background effects in ion-atom collisions are commented upon. Future aspects of atomic Coulomb excitation by incident nuclei and ions are discussed. The interplay between Coulomb induced processes and united atom phenomena is especially mentioned. The simple ionization models have yielded valuable insights but it is suggested that this branch of collision physics has reached a turning point where new and more advanced and unifying models are needed. (JIW)

Limitation of population's irradiation by natural sources of ionizing radiation

International Nuclear Information System (INIS)

Krisyuk, Eh.M.

1989-01-01

Review of works devoted to evaluating the human irradiation doses at the expense of the main sources of ionizing radiation, is given. It is shown that the human irradiation doses at the expense of DDP can be reduced 10 times and more. However to realize such measures it is necessary to study the efficiency and determine the cost of various protective activities as well as to develop the criteria of their realization necessity

Ionization detectors, ch. 3

International Nuclear Information System (INIS)

Sevcik, J.

1976-01-01

Most measuring devices used in gas chromatography consist of detectors that measure the ionization current. The process is based on the collision of a moving high-energy particle with a target particle that is ionised while an electron is freed. The discussion of the conditions of the collision reaction, the properties of the colliding particles, and the intensity of the applied field point to a unified classification of ionisation detectors. Radioactive sources suitable for use in these detectors are surveyed. The slow-down mechanism, recombination and background current effect are discussed

Dynamics of tunneling ionization using Bohmian mechanics

Science.gov (United States)

Douguet, Nicolas; Bartschat, Klaus

2018-01-01

Recent attoclock experiments and theoretical studies regarding the strong-field ionization of atoms by few-cycle infrared pulses revealed features that have attracted much attention. Here we investigate tunneling ionization and the dynamics of the electron probability using Bohmian mechanics. We consider a one-dimensional problem to illustrate the underlying mechanisms of the ionization process. It is revealed that in the major part of the below-the-barrier ionization regime, in an intense and short infrared pulse, the electron does not tunnel through the entire barrier, but rather starts already from the classically forbidden region. Moreover, we highlight the correspondence between the probability of locating the electron at a particular initial position and its asymptotic momentum. Bohmian mechanics also provides a natural definition of mean tunneling time and exit position, taking account of the time dependence of the barrier. Finally, we find that the electron can exit the barrier with significant kinetic energy, thereby corroborating the results of a recent study [N. Camus et al., Phys. Rev. Lett. 119, 023201 (2017), 10.1103/PhysRevLett.119.023201].

Modeling the Thermal Signature of Natural Backgrounds

National Research Council Canada - National Science Library

Gamborg, Marius

2002-01-01

Two measuring stations have been established the purpose being to collect comprehensive databases of thermal signatures of background elements in addition to the prevailing meteorological conditions...

The Application of Resonance-Enhanced Multiphoton Ionization Technique in Gas Chromatography Mass Spectrometry

Directory of Open Access Journals (Sweden)

Adan Li

2014-01-01

Full Text Available Gas chromatography resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (GC/REMPI-TOFMS using a nanosecond laser has been applied to analyze the 16 polycyclic aromatic hydrocarbons (PAHs. The excited-state lifetime, absorption characters, and energy of electronic states of the 16 PAHs were investigated to optimize the ionization yield. A river water sample pretreated by means of solid phase extraction was analyzed to evaluate the performance of the analytical instrument. The results suggested that REMPI is superior to electron impact ionization method for soft ionization and suppresses the background signal due to aliphatic hydrocarbons. Thus, GC/REMPI-TOFMS is a more reliable method for the determination of PAHs present in the environment.

Free-air ionization intensity in the lower atmosphere due to cosmic-ray

International Nuclear Information System (INIS)

Urabe, Itsumasa; Katsurayama, Kousuke

1979-01-01

Being able to be determined by subtracting the gamma-ray ionization intensity from that obtained with ionization chamber, cosmic-ray ionization intensity in free air was estimated by using with 15l air-filled ionization chamber and 3''diameter spherical NaI(Tl) scintillation spectrometer. Optimum applied voltage to 15l air-filled ionization chamber was determined in accordance with Scott and Greening's formula to obtain the ionization intensity caused by gamma-rays and cosmic-rays. Pulse-height distribution of cosmic-rays created in 3''diameter spherical NaI(Tl) scintillation spectrometer was investigated for the precise determination of gamma-ray ionization intensity. Field measurements were carried out by using with these two instruments at about 1.5 meter above the ground in the several locations around Research Reactor Institute of Kyoto University. Cosmic-ray ionization intensity in free air was estimated from the results obtained with air-filled ionization chamber and was 3.33 +- 0.15 μR/hr equivalent in natural environment near Research Reactor Institute of Kyoto University. (author)

Air-surface exchange measurements of gaseous elemental mercury over naturally enriched and background terrestrial landscapes in Australia

Directory of Open Access Journals (Sweden)

G. C. Edwards

2013-05-01

Full Text Available This paper presents the first gaseous elemental mercury (GEM air-surface exchange measurements obtained over naturally enriched and background (−1 Hg terrestrial landscapes in Australia. Two pilot field studies were carried out during the Australian autumn and winter periods at a copper-gold-cobalt-arsenic-mercury mineral field near Pulganbar, NSW. GEM fluxes using a dynamic flux chamber approach were measured, along with controlling environmental parameters over three naturally enriched and three background substrates. The enriched sites results showed net emission to the atmosphere and a strong correlation between flux and substrate Hg concentration, with average fluxes ranging from 14 ± 1 ng m−2 h−1 to 113 ± 6 ng m−2 h−1. Measurements at background sites showed both emission and deposition. The average Hg flux from all background sites showed an overall net emission of 0.36 ± 0.06 ng m−2 h−1. Fluxes show strong relationships with temperature, radiation, and substrate parameters. A compensation point of 2.48, representative of bare soils was determined. For periods of deposition, dry deposition velocities ranged from 0.00025 cm s−1 to 0.0083 cm s−1 with an average of 0.0041 ± 0.00018 cm s−1, representing bare soil, nighttime conditions. Comparison of the Australian data to North American data suggests the need for Australian-specific mercury air-surface exchange data representative of Australia's unique climatic conditions, vegetation types, land use patterns and soils.

Ionizing radiations and health. Exposures, epidemiological surveillance and sociological monitoring measurements

International Nuclear Information System (INIS)

Spira, Alfred; Boutou, Odile

1999-01-01

This paper draws attention to the epidemiological effect of natural and artificial ionizing radiation exposures on man. It describes ionizing radiation sources from nuclear facilities and medical establishments. The case here is in the region of La Hague in France where 4800 employees are exposed to ionizing radiations. The topic of leukemia research and thyroid studies for children in the region are discussed. The impact of radiations on fertility, life quality is covered. Finally, national propositions to establish a monitoring measurement system is also discussed including the personnel and the general population exposed

Shock velocity in weakly ionized nitrogen, air, and argon

International Nuclear Information System (INIS)

Siefert, Nicholas S.

2007-01-01

The goal of this research was to determine the principal mechanism(s) for the shock velocity increase in weakly ionized gases. This paper reports experimental data on the propagation of spark-generated shock waves (1< Mach<3) into weakly ionized nitrogen, air, and argon glow discharges (1 < p<20 Torr). In order to distinguish between effects due solely to the presence of electrons and effects due to heating of the background gas via elastic collisions with electrons, the weakly ionized discharge was pulsed on/off. Laser deflection methods determined the shock velocity, and the electron number density was collected using a microwave hairpin resonator. In the afterglow of nitrogen, air, and argon discharges, the shock velocity first decreased, not at the characteristic time for electrons to diffuse to the walls, but rather at the characteristic time for the centerline gas temperature to equilibrate with the wall temperature. These data support the conclusion that the principal mechanism for the increase in shock velocity in weakly ionized gases is thermal heating of the neutral gas species via elastic collisions with electrons

The toxic effects of ionizing radiations

International Nuclear Information System (INIS)

Draghita Payet, A.C.

2006-06-01

The sources of radiations to which the human body is subjected are of natural or artificial origin and the irradiation of the human body can take place either by internal or external way. The ionizing radiations act at several levels of the human body, the main thing being the molecule of DNA. The ionizing radiations have no specificity, the effects on the human body can be: somatic, genetic or hereditary, teratogen. In the case of a human being irradiation, we proceed to the diagnosis and to the treatment of the irradiated person, however, to decrease the incidence of injuries we use the radiation protection. The treatment if necessary will be established according to the irradiation type. (N.C.)

Air filled ionization chambers and their response to high LET radiation

DEFF Research Database (Denmark)

Kaiser, Franz-Joachim; Bassler, Niels; Tölli, Heikki

Background Air filled ionization chambers (ICs) are widely used for absolute dosimetry, not only in photon beams but also in beams of heavy charged particles. Within the IC, electron hole pairs are generated by the energy deposition originating from incoming radiation. High-LET particles create......-plate ionization chamber exposed to heavy ions Phys. Med. Biol. 43 3549–58, 1998. ELSAESSER, T. et al.: Impact of track structure on biological treatment planning ion ion radiotherapy. New Journal pf Physics 10. 075005, 2008...

Determination of Nerve Agent Metabolites by Ultraviolet Femtosecond Laser Ionization Mass Spectrometry.

Science.gov (United States)

Hamachi, Akifumi; Imasaka, Tomoko; Nakamura, Hiroshi; Li, Adan; Imasaka, Totaro

2017-05-02

Nerve agent metabolites, i.e., isopropyl methylphosphonic acid (IMPA) and pinacolyl methylphosphonic acid (PMPA), were derivatized by reacting them with 2,3,4,5,6-pentafluorobenzyl bromide (PFBBr) and were determined by mass spectrometry using an ultraviolet femtosecond laser emitting at 267 and 200 nm as the ionization source. The analytes of the derivatized compounds, i.e., IMPA-PFB and PMPA-PFB, contain a large side-chain, and molecular ions are very weak or absent in electron ionization mass spectrometry. The use of ultraviolet femtosecond laser ionization mass spectrometry, however, resulted in the formation of a molecular ion, even for compounds such as these that contain a highly bulky functional group. The signal intensity was larger at 200 nm due to resonance-enhanced two-photon ionization. In contrast, fragmentation was suppressed at 267 nm (nonresonant two-photon ionization) especially for PMPA-PFB, thus resulting in a lower background signal. This favorable result can be explained by the small excess energy in ionization at 267 nm and by the low-frequency vibrational mode of a bulky trimethylpropyl group in PMPA.

[Ionizing and non-ionizing radiation (comparative risk estimations)].

Science.gov (United States)

Grigor'ev, Iu G

2012-01-01

The population has widely used mobile communication for already more than 15 years. It is important to note that the use of mobile communication has sharply changed the conditions of daily exposure of the population to EME We expose our brain daily for the first time in the entire civilization. The mobile phone is an open and uncontrollable source of electromagnetic radiation. The comparative risk estimation for the population of ionizing and non-ionizing radiation was carried out taking into account the real conditions of influence. Comparison of risks for the population of ionizing and non-ionizing radiation leads us to a conclusion that EMF RF exposure in conditions of wide use of mobile communication is potentially more harmful than ionizing radiation influence.

Radioecology teaching: evaluation of the background radiation levels from areas with high concentrations of radionuclides in soil

International Nuclear Information System (INIS)

Anjos, R M; Okuno, E; Gomes, P R S; Veiga, R; Estellita, L; Mangia, L; Uzeda, D; Soares, T; Facure, A; Brage, J A P; Mosquera, B; Carvalho, C; Santos, A M A

2004-01-01

The study of environmental radioactivity is a topic which is not usually included in physics courses in Brazilian and Latin American universities. Consequently, high-school teachers are not able to show experimentally or discuss with their students the effects of exposure to terrestrial radiation. This paper presents a laboratory experiment in a teaching programme on the physics of ionizing radiation. It is based on the evaluation of the background radiation levels from areas with high concentrations of natural or artificial radionuclides in the soil. A brief analysis of the theory behind the technique and a description of some measurements, including their interpretations, are presented

Effects of ionizing radiation upon natural populations and ecosystems. Final report. [Ecological perspectives in land use planning

Energy Technology Data Exchange (ETDEWEB)

McCormick, J.F.

1976-01-01

Accomplishments throughout a 10-year period summarized include: a study of the effects of radiation from a ..gamma.. source on the ecology of the El Verde rain forest in Puerto Rico, with emphasis on the role of secondary succession in the recovery of forest ecosystems following irradiation; the effects of light and temperature on gaseous exchange in trees using /sup 14/CO/sub 2/ as a tracer in Palcourea; the nature of the sensitivity of pine trees to ionizing radiation and the possible synergistic effects of elevated ozone levels on radiosensitivity; the combined effects of radioactive and thermal effluents on plant communities of a swamp hardwood forest; and the development of a new conceptual approach to the evaluation of environmental quality, with emphasis on ecological perspectives in land use planning. (CH)

Natural background radiation in Canada

International Nuclear Information System (INIS)

Grasty, R.L.; Carson, J.M.; Charbonneau, B.W.; Holman, P.B.

1984-01-01

Published airborne gamma ray survey data from 33 areas of Canada were used to compile information on the average ground level exposure from natural radiation. The exposures at ground level were calculated from the surface concentrations of potassium, uranium and thorium. The highest levels of radioactivity were found in northern Canada and were generally related to granitic rocks; the lowest levels with the Athabasca sandstone. Summer outdoor exposure rates have a population-weighted average of 3.7 +- 2.3 μR.h -1 , of which 48 percent orginated from potassium, 43 percent from the thorium series and 9 percent from the uranium series. This low level of radioactivity, compared to worldwide data, has resulted from erosion of a geologically old continental crust in which radioactivity decreases with depth. When seasonal variations of soil moisture and snow cover are considered, the annual population-weighted average outdoor exposure rate decreases to 2.8 +- 1.7 μR.h -1 corresponding to an annual outdoor dose-equivalent of 150 +- 90 μSV. Factors increasing the annual outdoor dose-equivalent are cosmic radiation (320 +- 30 μSV) and the internal radioactivity of the body (190 μSV). Using the ratio between indoor and outdoor values for worldwide published data, the average annual Canadian whole-body dose-equivalent from all sources of natural radiation is estimated to be 690 +-130 μSV

Ionization effects in electronic inner-shells of ionized atoms

International Nuclear Information System (INIS)

Shchornak, G.

1983-01-01

A review of the atomic physics of ionization atoms has been presented. Interaction and structure effects in atomic shells, correlated to the occurrence of vacancies in several subshells of the atom have been considered. The methods of calculations of atomic states and wave functions have been reviewed. The energy shift of characteristic X-rays is discussed as a function of the ionization stage of the atom. The influence of inner and outer-shell vacancies on the energy of the X-rays is shown in detail. The influence of chemical effects on the parameters of X-rays is also taken into account. Further on, the change of transition probabilities in radiative and non-radiative transitions by changing stage of ionization is discussed; and among them the leading part of Auger and Coster-Kronig transitions by the arearrangement of the atomic states is shown. The influence of non-radiative electronic transitions on ionization cross-sections for multiple ionization is discussed. Using these results, ionization cross-sections for direct and indirect processes for several ionization stages are given

Management in the protection from ionizing radiation

International Nuclear Information System (INIS)

Radunovic, Miodrag; Nikolic, Krsto; Rakic, Goran

2008-01-01

There are numerous types and forms of endangering working and living environment, ranging from natural disasters to nuclear accidents. Challenges of the New Age determined that most of the countries reviewed its strategic decisions in the system of protection from ionizing radiation and nuclear safety and defined in a new way the threats, which could considerably imperil health of the population and national interests as well. Excessive radiation of the population became a serious and actual problem in the era of increasingly mass application of ionizing radiation, especially in medicine. The goal of this work is to reduce the risk through using knowledge and existing experiences, in particular when it comes to ionizing radiation in medicine. Optimization of the protection in radiology actually means an effort to find the compromise between quality information provided by diagnostics procedure and quality effects of therapy procedure on one side and dose of radiation received by patients on the other. Criteria for the quality management in the protection from ionizing radiation used in diagnostic radiology was given by the European Commission: European Guidelines on Quality Criteria for Diagnostic Radiographic Images, EUR, 16260. (author)

Radiation monitoring in a synchrotron light source facility using magnetically levitated electrode ionization chambers

International Nuclear Information System (INIS)

Ichiki, Hirofumi; Kawaguchi, Toshirou; Utsunomiya, Yoshitomo; Ishibashi, Kenji; Ikeda, Nobuo; Korenaga, Kazuhito

2009-01-01

We developed a highly accurate differential-type automatic radiation dosimeter to measure very low radiation doses. The dosimeter had two ionization chambers, each of which had a magnetically levitated electrode and it was operated in a repetitive-time integration mode. We first installed the differential-type automatic radiation dosimeter with MALICs at a high-energy electron accelerator facility (Kyushu Synchrotron Light Research Center Facility) and measured the background and ionizing radiations in the facility as well as the gaseous radiation in air. In the background dose measurements, the accuracy of the repetitive-time integration-type dosimeter was three times better than that of a commercial ionization chamber. When the radiation dose increased momentarily at the electron injection from the linac to the operating storage ring, the dosimeter with repetitive-time integral mode gave a successful response to the actual dose variation. The gaseous radiation dose in the facility was at the same level as that in Fukuoka City. We confirmed that the dosimeter with magnetically levitated electrode ionization chambers was usable in the accelerator facility, in spite of its limited response when operated in the repetitive-time integration mode. (author)

Gamma background irradiation. Standards and reality

International Nuclear Information System (INIS)

Miloslavov, V.

1998-01-01

The systematic deviation of the results of measuring the power of air dose absorbed from the natural gamma background radiation in Bulgaria is inadmissibly large and variable. This in turn augments the dispersion of results as well as the mean value relative to worldwide data, to an implausible level, hardly attributable to the variegated geographical relief of the country. Thus in practice local anthropogenic increases hardly lend themselves to detection and demonstration. In the Radiation Protection Standards (RPS-92) in effect in Bulgaria, and in other documents concerning the same radiation factors as well, the maximum allowable limits for the population as a whole are clearly specified on the basis of worldwide expertise along this line. As a rule these limits are being exceeded by the actually measured values, and for this reason the cited documents contain a clause stipulating that these limits do not refer to the natural radiation background and therefore the latter may be virtually ignored. Thus the basic risk factor for the population goes beyond control at levels commensurable with the officially established limits, its twofold increase inclusive. The maximum allowable limit becomes undefinable. Bearing in mind the fact that in compliance with the cited RPS-92 elimination of the technogenic ionizing radiation sources incorporated in the environment prior to 1992 is 'freezed', it is evident that exposure of the population to anthropogenic radiation becomes legally allowable in a much wider range than the one specified by world legislators. One may anticipate radiation induced health noxae for the population directly or by anthropogenic radiation stress on biocenosis. A relatively large part of the population is susceptible to the effect of low radiation doses. Presumably this contingent will augment as a result of eventual fluctuations. The casual relationship which is difficult to establish should be given due consideration in the analysis of the causes

Health consequences of ionizing radiation exposure

International Nuclear Information System (INIS)

Dalci, D.; Dorter, G.; Guclu, I.

2004-01-01

The increasing use of ionizing radiations all over the world induces an ever increasing interest of the professionals as well as of the whole society in health protection and the risk due to these practices. Shortly after its discovery, it was recognized that ionizing radiation can have adverse health effects and knowledge of its detrimental effects has accumulated. The fact that ionizing radiation produces biological damage has been known for many years. The biological effects of ionizing radiation for radiation protection considerations are grouped into two categories: The deterministic and the stochastic ones. Deterministic radiation effects can be clinically diagnosed in the exposed individual and occur when above a certain 'threshold' an appropriately high dose is absorbed in the tissues and organs to cause the death of a large number of cells and consequently to impair tissue or organ functions early after exposure. A clinically observable biological effect (Acute Radiation Syndromes, ARS) that occurs days to months after an acute radiation dose. ARS is a complex of acute injury manifestations that occur after a sufficiently large portion of a person's body is exposed to a high dose of ionizing radiation. Such irradiation initially injures all organs to some extent, but the timing and extent of the injury manifestations depend upon the type, rate, and dose of radiation received. Stochastic radiation effects are the chronic effects of radiation result from relatively low exposure levels delivered over long periods of time. These are sort of effects that might result from occupational exposure, or to the background exposure levels (includes radioactive pollution). Such late effects might be the development of malignant (cancerous) disease and of the hereditary consequences. These effects may be observed many years after the radiation exposure. There is a latent period between the initial radiation exposure and the development of the biological effect. In this

Simulations of Hall reconnection in partially ionized plasmas

Science.gov (United States)

Innocenti, Maria Elena; Jiang, Wei; Lapenta, Giovanni

2017-04-01

Magnetic reconnection occurs in the Hall, partially ionized regime in environments as diverse as molecular clouds, protostellar disks and regions of the solar chromosphere. While much is known about Hall reconnection in fully ionized plasmas, Hall reconnection in partially ionized plasmas is, in comparison, still relatively unexplored. This notwithstanding the fact that partial ionization is expected to affect fundamental processes in reconnection such as the transition from the slow, fluid to the fast, kinetic regime, the value of the reconnection rate and the dimensions of the diffusion regions [Malyshkin and Zweibel 2011 , Zweibel et al. 2011]. We present here the first, to our knowledge, fully kinetic simulations of Hall reconnection in partially ionized plasmas. The interaction of electrons and ions with the neutral background is realistically modelled via a Monte Carlo plug-in coded into the semi-implicit, fully kinetic code iPic3D [Markidis 2010]. We simulate a plasma with parameters compatible with the MRX experiments illustrated in Zweibel et al. 2011 and Lawrence et al. 2013, to be able to compare our simulation results with actual experiments. The gas and ion temperature is T=3 eV, the ion to electron temperature ratio is Tr=0.44, ion and electron thermal velocities are calculated accordingly resorting to a reduced mass ratio and a reduced value of the speed of light to reduce the computational costs of the simulations. The initial density of the plasma is set at n= 1.1 1014 cm-3 and is then left free to change during the simulation as a result of gas-plasma interaction. A set of simulations with initial ionisation percentage IP= 0.01, 0.1, 0.2, 0.6 is presented and compared with a reference simulation where no background gas is present (full ionization). In this first set of simulations, we assume to be able to externally control the initial relative densities of gas and plasma. Within this parameter range, the ion but not the electron population is

α spectrometry grid ionization chamber: improvement of the characteristics

International Nuclear Information System (INIS)

Le Du, R.; Miltenberger, B.

1968-01-01

The rise time of the signals obtained with a grid ionization chamber depends on the orientation in the chamber and on the mobility of the ionization components. Our grid chambers are fitted with an electronic system which analyses the signals due to the electronic ionization components which are collected on the plate and on the source holder. By obtaining coincidence between these two signals, it is possible to select paths of any given orientation. Using this principle we have built an electronic collimator which does not have the disadvantages of a mechanical collimator for alpha spectra studies, and which, further, considerably reduces the background of the chamber. Simultaneously with the study of the improvement of a spectra with our device, we have been able to dissociate the contributions of back-diffusion and of self-absorption phenomena to the activity of an alpha source; some results will be presented. (authors) [fr

Doses and biological effect of ionizing radiation

International Nuclear Information System (INIS)

Hrynkiewicz, A.

1993-01-01

The aim of the monograph is to review practical aspects of dosimetry. The work describes basic units which are used in dosimetry and natural as well as industrial sources of ionizing radiation. Information given in the monograph help in assessment of the radiation risk. 8 refs, 15 tabs

Estimation of the radiological background and dose assessment in areas with naturally occurring uranium geochemical anomalies—a case study in the Iberian Massif (Central Portugal)

International Nuclear Information System (INIS)

Pereira, A.J.S.C.; Neves, L.J.P.F.

2012-01-01

Naturally occurring uranium geochemical anomalies, representative of the several thousand recognized in the Portuguese section of the Iberian Massif and outcropping in three target areas with a total of a few thousand square metres, were subjected to a detailed study (1:1000 scale) to evaluate the radiological health-risk on the basis of a dose assessment. To reach this goal some radioactive isotopes from the uranium, thorium and potassium radioactive series were measured in 52 samples taken from different environmental compartments: soils, stream sediments, water, foodstuff (vegetables) and air; external radiation was also measured through a square grid of 10 × 10 m, with a total of 336 measurements. The results show that some radioisotopes have high activities in all the environmental compartments as well as a large variability, namely for those of the uranium decay chain, which is a common situation in the regional geological setting. Isotopic disequilibrium is also common and led to an enrichment of several isotopes in the different pathways, as is the case of 226 Ra; maximum values of 1.76 Bq L −1 (water), 986 Bq kg −1 (soils) and 18.9 Bq kg −1 (in a turnip sample) were measured. On the basis of a realistic scenario combined with the experimental data, the effective dose from exposure to ionizing radiation for two groups of the population (rural and urban) was calculated; the effective dose is variable between 8.0 and 9.5 mSv year −1 , which is 3–4 times higher than the world average. Thus, the radiological health-risk for these populations could be significant and the studied uranium anomalies must be taken into account in the assessment of the geochemical background. The estimated effective dose can also be used as typical of the background of the Beiras uranium metalogenetic province and therefore as a “benchmark” in the remediation of the old uranium mining sites. - Highlights: ► The importance of small-sized naturally occurring uranium

Calibration of ionization chamber survey meter

International Nuclear Information System (INIS)

Kadhim, A.K.; Kadni, T.B.

2016-01-01

Radiation measuring devices need to process calibration which lose their sensitivity and the extent of the response and the amount of stability under a changing conditions from time to time and this period depends on the nature and use of field in which used devices. A comparison study was done toa (45 I P) ( ionization chamber survey meter) and this showed the variation factor in five different years. This study also displayed the concept of radiation instrument calibration and necessity of every year calibration of them.In this project we used the five years calibration data for ionization chamber survey meter model Inspector (1/C F). the value deviation (∆ %) of Cfs for four years of calibration in comparison of C F for the year 2007 are very high and the device under research is not good to use in field and reliable because the ionization chamber is very sensitive to humidity and must calibrate a year or less, or due ing every two years and must maintain carefully to reduce the discarded effects the measurements.

Guided ionization waves: Theory and experiments

International Nuclear Information System (INIS)

Lu, X.; Naidis, G.V.; Laroussi, M.; Ostrikov, K.

2014-01-01

This review focuses on one of the fundamental phenomena that occur upon application of sufficiently strong electric fields to gases, namely the formation and propagation of ionization waves–streamers. The dynamics of streamers is controlled by strongly nonlinear coupling, in localized streamer tip regions, between enhanced (due to charge separation) electric field and ionization and transport of charged species in the enhanced field. Streamers appear in nature (as initial stages of sparks and lightning, as huge structures—sprites above thunderclouds), and are also found in numerous technological applications of electrical discharges. Here we discuss the fundamental physics of the guided streamer-like structures—plasma bullets which are produced in cold atmospheric-pressure plasma jets. Plasma bullets are guided ionization waves moving in a thin column of a jet of plasma forming gases (e.g., He or Ar) expanding into ambient air. In contrast to streamers in a free (unbounded) space that propagate in a stochastic manner and often branch, guided ionization waves are repetitive and highly-reproducible and propagate along the same path—the jet axis. This property of guided streamers, in comparison with streamers in a free space, enables many advanced time-resolved experimental studies of ionization waves with nanosecond precision. In particular, experimental studies on manipulation of streamers by external electric fields and streamer interactions are critically examined. This review also introduces the basic theories and recent advances on the experimental and computational studies of guided streamers, in particular related to the propagation dynamics of ionization waves and the various parameters of relevance to plasma streamers. This knowledge is very useful to optimize the efficacy of applications of plasma streamer discharges in various fields ranging from health care and medicine to materials science and nanotechnology

The origins of the metrology of ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Paschoa, Anselmo S. [Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil). Dept. de Fisica]. E-mail: aspas@itaipu.vdg.fis.puc-rio.br

2000-07-01

Metrology of ionizing radiation started soon after the discovery of radioactivity. However, the modern metrology of ionizing radiation can be considered a by product of the Manhattan Project. When this mammoth effort to produce the first nuclear weapons was initiated, little was known about some of the properties of natural elements, though the phenomenon of natural radioactivity was already known for almost half a century. Less was known about the radioactive materials involved in that project. The amount of those materials which had to be handled were higher than any amount of {sup 226} Ra and {sup 228} Ra ever used thus far. The first atomic piles produced concentration levels of radioactivity much higher than any level known before. There was then a threat not only for the health of hundred of technicians and scientists, but also for thousands of workers. The secrecy involving that project would not allow much to be told about the radioactive hazards. There was, however, the need to protect workers and the public in General against unnecessary exposures to ionizing radiation. The origin of the standards used in radiological protection from pre-world war II and their remarkable evolution during and immediately after this war will be discussed in the paper. (author)

The origins of the metrology of ionizing radiation

International Nuclear Information System (INIS)

Paschoa, Anselmo S.

2000-01-01

Metrology of ionizing radiation started soon after the discovery of radioactivity. However, the modern metrology of ionizing radiation can be considered a by product of the Manhattan Project. When this mammoth effort to produce the first nuclear weapons was initiated, little was known about some of the properties of natural elements, though the phenomenon of natural radioactivity was already known for almost half a century. Less was known about the radioactive materials involved in that project. The amount of those materials which had to be handled were higher than any amount of 226 Ra and 228 Ra ever used thus far. The first atomic piles produced concentration levels of radioactivity much higher than any level known before. There was then a threat not only for the health of hundred of technicians and scientists, but also for thousands of workers. The secrecy involving that project would not allow much to be told about the radioactive hazards. There was, however, the need to protect workers and the public in General against unnecessary exposures to ionizing radiation. The origin of the standards used in radiological protection from pre-world war II and their remarkable evolution during and immediately after this war will be discussed in the paper. (author)

Updated estimates of the proportion of childhood leukaemia incidence in Great Britain that may be caused by natural background ionising radiation

International Nuclear Information System (INIS)

Little, Mark P; Wakeford, Richard; Kendall, Gerald M

2009-01-01

The aetiology of childhood leukaemia remains generally unknown, although exposure to moderate and high levels of ionising radiation, such as was experienced during the atomic bombings of Japan or from radiotherapy, is an established cause. Risk models based primarily upon studies of the Japanese A-bomb survivors imply that low-level exposure to ionising radiation, including to ubiquitous natural background radiation, also raises the risk of childhood leukaemia. In a recent paper (Wakeford et al 2009 Leukaemia 23 770-6) we estimated the proportion of childhood leukaemia incidence in Great Britain attributable to natural background radiation to be about 20%. In this paper we employ the two sets of published leukaemia risk models used previously, but use recently published revised estimates of natural background radiation doses received by the red bone marrow of British children to update the previous results. Using the newer dosimetry we calculate that the best estimate of the proportion of cases of childhood leukaemia in Great Britain predicted to be attributable to this source of exposure is 15-20%, although the uncertainty associated with certain stages in the calculation (e.g. the nature of the transfer of risk between populations and the pertinent dose received from naturally occurring alpha-particle-emitting radionuclides) is significant. The slightly lower attributable proportions compared with those previously derived by Wakeford et al (Leukaemia 2009 23 770-6) are largely due to the lower doses (and in particular lower high LET doses) for the first year of life.

Morphological and transcriptional response of an anhydrobiotic insect to ionizing radiation and desiccation: steps forward in understanding molecular background of extreme radioresistance in higher eukaryotes

Science.gov (United States)

Gusev, Oleg; Novikova, Nataliya; Sychev, Vladimir; Okuda, Takashi; Kikawada, Takahiro; Sakashita, Tetsuya; Mukae, Kyosuke

2012-07-01

Life in extreme or drastically changing environments in many cases leads to evolutionary evolvement of mechanisms of cross-resistance to different abiotic stresses, often never actually faced by the organism in its natural habitat. Larvae of the sleeping chironomidPolypedilum vanderplanki (Diptera) are able to resist complete desiccation and in the dry form survive under excess of various abiotic stresses, including exposure to space environment. One of the most intriguing features of the anhydrobiotic larvae is resistance to extremely high doses of different types of ionizing radiation. To understand the cross-tolerance mechanism, we have analyzed the structural changes in the nuclear DNA using transmission electron microscopy and DNA comet assays in relation to anhydrobiosis and radiation. We find that dehydration causes alterations in chromatin structure and a severe fragmentation of nuclear DNA in the cells of the larvae despite successful anhydrobiosis. The DNA fragmentation level and the recovery of DNA integrity in the rehydrated after anhydrobiosis larvae were similar to those of hydrated larvae irradiated with 70 Gy of high-linear energy transfer (LET) ions (4He+). In comparison, low-LET radiation (gamma rays) of the same dose causes less initial damage to the larvae, and recovery of DNA repair is complete within 24 h. Genome-wide analysis of mRNA expression in the larvae revealed that a large group of genes (including antioxidants, anhydrobiosis-specific biomolecules and protein-reparation enzymes) showed a similar patterns of activity in response to both desiccation and ionizing radiation. We conclude that t one of the factors explaining the relationship between the resistance to ionizing radiation and the ability to undergo anhydrobiosis in the sleeping chironomid would be an adaptation to desiccation-inflicted proteins and nuclear DNA damage.

The characteristics of peripheral blood leukocytes in persons working with ionizing radiation sources

International Nuclear Information System (INIS)

Zykova, I.A.; Sokolova, N.B.; Yas'kova, V.Z.

1984-01-01

Functional and qualitative changes of peripheral blood cellular composition were studied in persons working over a long period of time with ionizing radiation sources under the action of various factors of production upon an organism. Appression of a function and increase of T-lymphocyte chromosome damages were revealed against the background of a decrease both of enzymatic activity level and leukocyte number in persons operating for a long time (more than 10 years) with ionizing radiation sources. Discovered changes occurred under the action upon a human being not only of small doses of ionizing radiation but a whole complex of industrial factors which may initiate changes of adapted character

Escape of ionizing radiation from high redshift dwarf galaxies: role of AGN feedback

Science.gov (United States)

Trebitsch, Maxime; Volonteri, Marta; Dubois, Yohan; Madau, Piero

2018-05-01

While low mass, star forming galaxies are often considered as the primary driver of reionization, their actual contribution to the cosmic ultraviolet background is still uncertain, mostly because the escape fraction of ionizing photons is only poorly constrained. Theoretical studies have shown that efficient supernova feedback is a necessary condition to create paths through which ionizing radiation can escape into the intergalactic medium. We investigate the possibility that accreting supermassive black holes in early dwarf galaxies may provide additional feedback and enhance the leakage of ionizing radiation. We use a series of high resolution cosmological radiation hydrodynamics simulations where we isolate the different sources of feedback. We find that supernova feedback prevents the growth of the black hole, thus quenching its associated feedback. Even in cases where the black hole can grow, the structure of the interstellar medium is strongly dominated by supernova feedback. We conclude that, in the dwarf galaxy regime, supermassive black holes do not appear to play a significant role in enhancing the escape fraction and in contributing to the early UV background.

Si no. 43 of 1991 - European Communities (ionizing radiation) regulations, 1991

International Nuclear Information System (INIS)

1991-01-01

These Regulations entered into force on 5 April 1991 and repeal the Factories Ionizing Radiations (Sealed Sources) Regulations, 1972 and the Factories Ionizing Radiations (Unsealed Sources) Regulations, 1972. They were made in implementation of the European Communities' Council Directive 80/836 Euratom of 15 July 1980, as amended by Council Directive 84/467 Euratom of 3 September 1984, laying down the basic safety standards for the health protection of the general public and workers against the dangers of ionizing radiation. They also complement the Nuclear Energy (General Control of Fissile Fuels, Radioactive Substances and Irradiation Apparatus) Order, 1977 with regard to licensing requirements. They apply to the production, processing, handling, use, transport, storage, etc. of natural and artificial radioactive substances and to any other activity which involves a hazard arising from ionizing radiation. (NEA) [fr

Occupational radiation protection: Protecting workers against exposure to ionizing radiation. Contributed papers

International Nuclear Information System (INIS)

2003-07-01

Occupational exposure to ionizing radiation can occur in a range of industries, mining and milling; medical institutions, educational and research establishments and nuclear fuel cycle facilities. The term 'occupational exposure' refers to the radiation exposure incurred by a worker, which is attributable to the worker's occupation and committed during a period of work. According to the latest (2000) Report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), an estimated 11 million workers are monitored for exposure to ionizing radiation. They incur radiation doses attributable to their occupation, which range from a small fraction of the global average background exposure to natural radiation up to several times that value. It should be noted that the UNSCEAR 2000 Report describes a downward trend in the exposure of several groups of workers, but it also indicates that occupational exposure is affecting an increasingly large group of people worldwide. The International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources (BSS), which are co-sponsored by, inter alia, the International Atomic Energy Agency (IAEA), the International Labour Organization (ILO), the OECD Nuclear Energy Agency (NEA) and the World Health Organization (WHO), establish a system of radiation protection which includes radiation dose limits for occupational exposure. Guidance supporting the requirements of the BSS for occupational protection is provided in three interrelated Safety Guides, jointly sponsored by the IAEA and the ILO. These Guides describe, for example, the implications for employers in discharging their main responsibilities (such as setting up appropriate radiation protection programmes) and similarly for workers (such as properly using the radiation monitoring devices provided to them). The IAEA i organized its first International Conference on Occupational Radiation Protection. The

Analysis of abused drugs by selected ion monitoring: quantitative comparison of electron impact and chemical ionization

International Nuclear Information System (INIS)

Foltz, R.L.; Knowlton, D.A.; Lin, D.C.K.; Fentiman, A.F. Jr.

1975-01-01

A comparison was made of the relative sensitivities of electron impact and chemical ionization when used for selected ion monitoring analysis of commonly abused drugs. For most of the drugs examined chemical ionization using ammonia as the reactant gas gave the largest single m/e ion current response per unit weight of sample. However, if maximum sensitivity is desired it is important to evaluate electron impact and chemical ionization with respect to both maximum response and degree of interference from background and endogenous materials

Ring magnetron ionizer

International Nuclear Information System (INIS)

Alessi, J.G.

1986-01-01

A ring magnetron D - charge exchange ionizer has been built and tested. An H - current of 500 μA was extracted with an estimated H 0 density in the ionizer of 10 12 cm -3 . This exceeds the performance of ionizers presently in use on polarized H - sources. The ionizer will soon be tested with a polarized atomic beam

Resistance of Feather-Associated Bacteria to Intermediate Levels of Ionizing Radiation near Chernobyl

OpenAIRE

Ruiz-Gonz?lez, Mario Xavier; Czirj?k, G?bor ?rp?d; Genevaux, Pierre; M?ller, Anders Pape; Mousseau, Timothy Alexander; Heeb, Philipp

2016-01-01

Ionizing radiation has been shown to produce negative effects on organisms, although little is known about its ecological and evolutionary effects. As a study model, we isolated bacteria associated with feathers from barn swallows Hirundo rustica from three study areas around Chernobyl differing in background ionizing radiation levels and one control study site in Denmark. Each bacterial community was exposed to four different ? radiation doses ranging from 0.46 to 3.96 kGy to test whether ch...

Investigation of ionizing sublethal doses effects on endogenous radioresistance background

International Nuclear Information System (INIS)

Kudryashov, Yu.B.; Goncharenko, E.N.; Antonova, S.V.; Akhalaya, M.Ya.; Bajzhumanov, A.A.; Shestakova, S.V.

1997-01-01

Sublethal doses of X-radiation (0.5 Gy and 1 Gy) caused the alterations in levels of main components of endogenous radioresistance background in rat tissues. There were demonstrated the decrease of serotonin content in stomach mocosa and spleen, adrenalin, noradrenalin and corticosteroids contents in adrenal glands, nonprotein thiols content in spleen and the increase of lipid peroxide level in serum on the 3-14 days after irradiation. The recovery of the investigated parameters was occurred to the 21 day after exposure. (author)

State of the art of D ampersand D Instrumentation Technology: Alpha counting in the presence of high background

International Nuclear Information System (INIS)

Dickerman, C.E.

1995-08-01

Discrimination of alpha activity in the presence of a high radiation background has been identified as an area of concern to be studied for D ampersand D applications. Upon evaluating the range of alpha detection needs for D ampersand D operations, we have expanded this study to address the operational concern of greatly expediting alpha counting of rough surfaces and rubble. Note that the term, ''rough surfaces'' includes a wide range of practical cases, including contaminated equipment and work surfaces. We have developed provisional applications requirements for instrumentation of this type; and we also have generated the scope of a program of instrument evaluation and testing, with emphasis on practical implementation. In order to obtain the full operational benefit of alpha discrimination in the presence of strong beta-gamma radiation background, the detection system must be capable of some form of remote or semi-remote operation in order to reduce operator exposure. We have identified a highly promising technique, the long-range alpha detector (LRAD), for alpha discrimination in the presence of high radiation background. This technique operates upon the principle of transporting alphaionized air to an ionization detector. A transport time within a few seconds is adequate. Neither the provisional requirements nor the evaluation and testing scope were expressly tailored to force the selection of a LRAD technology, and they could be used as a basis for studies of other promising technologies. However, a technology that remotely detects alpha-ionized air (e. g., LRAD) is a natural fit to the key requirements of rejection of high background at the survey location and operator protection. Also, LRAD appears to be valuable for D ampersand D applications as a means of greatly expediting surface alpha-activity surveys that otherwise would require performing time-consuming scans over surfaces of interest with alpha detector probes, and even more labor-intensive surface

Ionizing radiation in 21st century

International Nuclear Information System (INIS)

Jaworowski, Zbigniew

2005-01-01

The paper begins with the author's personal experience in Poland on the occasion of Chernobyl nuclear accident followed by main lessons that the author could deduce from the accident. After the discovery of ionizing radiation at the end of 19th century, social perception has altered between acceptance and rejection stemming from recognition of the basic aspects: usefulness for medical applications and for technical and scientific aims, beneficial effects of their low levels, and harmful effects of high levels. The author explains how linear no-threshold (LNT) assumption according to which even the lowest, near zero doses of radiation may cause cancer genetic harm has become established. Comparing the natural radioactivity of the earth's crust with the activity of much shorter-lived radioactive wastes from the nuclear power cycle, it is concluded that none of the man-made component of the radioactive wastes has higher-toxicity than the natural Th 232. The paper concludes by stating that one century has not been long enough to adapt mentally to ionizing radiation and radioactivity and perhaps 21st century will suffice for this adaptation. (S. Ohno)

Ionizing radiation as a source of both occupational and public exposure. Is there any difference between them? Conclusions for radiation protection practice

International Nuclear Information System (INIS)

Vassilev, G.

2000-01-01

The assessment of the radiation risk both from natural and occupational exposure is discussed, taking into account the values for the end of 20th century for Bulgaria. The natural background exposure in the country is in average of 2.3 mSv/a. The eternal exposure in different regions varies within the range of ±25%. The radon concentration in dwellings vary in wide range: from 2.5 to 250 Bq/m 3 at a geometrical mean of 22 Bq/m 3 (equilibrium equivalent concentration). Thus the natural exposure vary from 1.0 to 5 mSv/a. The occupational exposure in different fields is as follows: medicine - 1.0 mSv/a; science, education - 0.9 mSv/a; NPP workers - 2.0 mSv/a. Taking into account that this way the risk equalizes for each population group the following conclusions are made: necessity for rendering an account of the individual natural background exposure when occupational risk is assessed; building of an adequate national system for record and limitation of exposure my medical use of ionizing radiation; improvement of the system for limitation of the radon exposure; re-examination of dosimetry control for occupational exposure; reconsidering of the social compensation for radiation risk

Influence of NORMs on the natural background radiation level in petroleum-producing countries

International Nuclear Information System (INIS)

Ali, F.M.

2002-01-01

Naturally occurring radioactive materials (NORMs) which are found in the Earth's crust, in the form of 226 Ra and 228 Ra and their associated radionuclides, are brought to the surface of the ground as a result of oil production processes, and are known under the name of technologically enhanced natural radioactivity (TENR). These represent a potential hazard of significant scale. 226 Ra, an α emitter, represents a potential internal radiation exposure hazard to both workers and members of the public, arising from the inhalation and ingestion of the dust produced during cleaning operations for the descaling of pipes and separator tanks. In addition to this, a higher than normal background γ exposure rate is to be observed both around and directly at the areas where the mud from the separator tanks and pipe cleaning operations was routinely dumped. Therefore, the aim of this work was to present the data on radiation levels measured in contaminated areas located near to a number of oilfields in Egypt and in Syria. The decontamination processes undertaken and the precautions necessary to ensure elimination of the possible transport mechanisms for contaminated dust into public areas by wind are presented. (orig.)

Aluminum as a source of background in low background experiments

Energy Technology Data Exchange (ETDEWEB)

Majorovits, B., E-mail: bela@mppmu.mpg.de [MPI fuer Physik, Foehringer Ring 6, 80805 Munich (Germany); Abt, I. [MPI fuer Physik, Foehringer Ring 6, 80805 Munich (Germany); Laubenstein, M. [Laboratori Nazionali del Gran Sasso, INFN, S.S.17/bis, km 18 plus 910, I-67100 Assergi (Italy); Volynets, O. [MPI fuer Physik, Foehringer Ring 6, 80805 Munich (Germany)

2011-08-11

Neutrinoless double beta decay would be a key to understanding the nature of neutrino masses. The next generation of High Purity Germanium experiments will have to be operated with a background rate of better than 10{sup -5} counts/(kg y keV) in the region of interest around the Q-value of the decay. Therefore, so far irrelevant sources of background have to be considered. The metalization of the surface of germanium detectors is in general done with aluminum. The background from the decays of {sup 22}Na, {sup 26}Al, {sup 226}Ra and {sup 228}Th introduced by this metalization is discussed. It is shown that only a special selection of aluminum can keep these background contributions acceptable.

Risk associated with occupational exposure to ionizing radiation kept in perspective

International Nuclear Information System (INIS)

Bonnell, J.A.; Harte, G.

1978-01-01

The risks associated with exposure to ionizing radiations are placed in perspective by a study of the natural incidence of those diseases in the United Kingdom that can be induced by radiation exposure. It is apparent that at ICRP recommended annual dose equivalent limits the small risks associated with exposure to ionizing radiations are acceptable, bearing in mind the obvious benefits that accrue from activities such as power production. This applies both to genetic and somatic diseases. (author)

Description of ionization in the molecular approach to atomic collisions. II

International Nuclear Information System (INIS)

Errea, L.F.; Mendez, L.; Riera, A.; Sevila, I.; Harel, C.; Jouin, H.; Pons, B.

2002-01-01

We complement a previous article [Harel et al., Phys. Rev. A 55, 287 (1997)] that studied the characteristics of the description of ionization by the molecular approach to atomic collisions, by comparing the wave functions with accurate counterparts. We show how the failure of the basis to describe the phase of the ionizing wave function results in a trapping of the corresponding population in some molecular channels. The time evolution of the molecular wave function then departs from the exact one and the ionization and capture mechanisms appear as interlocked. We thus elucidate the question of the 'natural' boundary of the molecular approach and draw further consequences as to the choice of pseudostates and the use of translation factors

Tumorigenic and tumoricidal actions of ionizing radiations

International Nuclear Information System (INIS)

Sanders, C.L.; Kathren, R.L.

1983-01-01

The book is divided into two approximately equal parts. The first four chapters are relatively lengthy and cover the basic principles of radiation biology, carcinogenesis and therapy, along with a brief introduction to radiological physics to orient the reader without background in this specialized related discipline. The remainder consists of twenty-four relatively brief chapters, each covering the radiation biology of a specific organ, tissue, or systems tissues, with emphasis on the tumorigenic and tumoricidal action of ionizing radiations

Effects of Ionizing Radiation on Cellular Structures, Induced Instability, and Carcinogenesis

International Nuclear Information System (INIS)

Resat, Marianne S.; Arthurs, Benjamin J.; Estes, Brian J.; Morgan, william F.

2006-01-01

According to the American Cancer Society, the United States can expect 1,368,030 new cases of cancer in 2004 [1]. Among the many carcinogens Americans are exposed to, ionizing radiation will contribute to this statistic. Humans live in a radiation environment. Ionizing radiation is in the air we breathe, the earth we live on, and the food we eat. Man-made radiation adds to this naturally occurring radiation level thereby increasing the chance for human exposure. For many decades the scientific community, governmental regulatory bodies, and concerned citizens have struggled to estimate health risks associated with radiation exposures, particularly at low doses. While cancer induction is the primary concern and the most important somatic effect of exposure to ionizing radiation, potential health risks do not involve neoplastic diseases exclusively but also include somatic mutations that might contribute to birth defects and ocular maladies, and heritable mutations that might impact on disease risks in future generations. Consequently it is important we understand the effect of ionizing radiation on cellular structures and the subsequent long-term health risks associated with exposure to ionizing radiation

Ionization Collection in Detectors of the Cryogenic Dark Matter Search

Energy Technology Data Exchange (ETDEWEB)

Phipps, Arran T.J. [Univ. of California, Berkeley, CA (United States)

2016-01-01

Determining the composition of dark matter is at the forefront of modern scientific research. There is compelling evidence for the existence of vast quantities of dark matter throughout the universe, however it has so-far eluded all direct detection efforts and its identity remains a mystery. Weakly interacting massive particles (WIMPs) are a favored dark matter candidate and have been the primary focus of direct detection for several decades. The Cryogenic Dark Matter Search (CDMS) has developed the Z-dependent Ionization and Phonon (ZIP) detector to search for such particles. Typically made from germanium, these detectors are capable of distinguishing between electromagnetic background and a putative WIMP signal through the simultaneous measurement of ionization and phonons produced by scattering events. CDMS has operated several arrays of these detectors at the Soudan Underground Laboratory (Soudan, MN, USA) resulting in many competitive (often world-leading) WIMP exclusion limits. This dissertation focuses on ionization collection in these detectors under the sub-Kelvin, low electric field, and high crystal purity conditions unique to CDMS. The design and performance of a fully cryogenic HEMT-based amplifier capable of achieving the SuperCDMS SNOLAB ionization energy resolution goal of 100 eVee is presented. The experimental apparatus which has been used to record electron and hole properties under CDMS conditions is described. Measurements of charge transport, trapping, and impact ionization as a function of electric field in two CDMS detectors are shown, and the ionization collection efficiency is determined. The data is used to predict the error in the nuclear recoil energy scale under both CDMSlite and iZIP operating modes. A two species, two state model is developed to describe how ionization collection and space charge generation in CDMS detectors are controlled by the presence of “overcharged” D- donor and A+ acceptor impurity states. The thermal

Measurement of high natural background radiation levels by TLD at Cox's Bazar coastal areas in Bangladesh

International Nuclear Information System (INIS)

Mollah, A.S.; Rahman, M.M.; Koddus, M.A.; Husain, S.R.; Malek, M.A.

1987-01-01

High natural background radiation levels at the Cox's Bazar coastal areas in Bangladesh were measured by LiF (TLD-100) dosemeters. The dose rates varied from 2621 to 35391 μGy.y -1 with a mean of 11968 μGy.y -1 . The average dose rate is found to significantly higher than the world average value. In order to formulate appropriate guidelines for radiation protection of the population in this area, the necessary recommendations are described. (author)

Study of the natural radiation background affected on the human body in some areas of Viet Nam

International Nuclear Information System (INIS)

Ngo Van Thanh

2008-01-01

The author had studied the natural radiation background in 68 districts belong 40 provinces and cities of Vietnam from 2002 to 2005. The estimated results clearly show that the average external irradiation dose levels and the average annual external radiation equivalent dose affected on the human body are 0.181± 0.0189 μSv/h and 1599 ± 171.8 μSv/year respectively, both are in normal limit; the highest levels are in Lai Chau district (Lai Chau province); the lowest levels are in Buon Ma Thuot city (DakLak province), Phuoc Son district (Quang Nam province), Tan An district (Long An province). The radon concentration in the human being and the average annual internal inhalation irradiation equivalent dose affected on the human beings are 26.9 ± 15.89 Bq/m 3 and 392.88 ± 231.99 μSv/year respectively; the maximums are in Nha Trang city (Khanh Hoa province), Bac Binh district (Binh Phuoc province); the minimums are in Vung Tau city (Ba Ria- Vung Tau province), Tan An district (Long An province), Rach Gia district (Kien Giang province). The terrestrial radionuclide concentrations in the cereals, foodstuffs (rice, meat, vegetables), water, earth and the average annual internal irradiation equivalent dose are 829.2 ± 38.06 Bq/kg and 229.3 ± 67.70 μSv/year respectively; the highest levels are in Phong Tho district (Lai Chau province), Dien Bien city; the lowest levels are in Dong Xoai district (Binh Phuoc province), Tan An district (Long An province). The average total annual natural radiation background effective equivalent dose level affected on the human body is 2206.9 ± 529.30 μSv/year; the highest levels are in Lai Chau district (Lai Chau province); the lowest levels are in Tan An district (Long An province). The 14 maps of Natural Radiation Background in several localized regions belong 40 provinces and cities of Viet Nam had been set up. These results can reserve for serviceman and public health in the both wartime and peacetime. (author)

Background radiation

International Nuclear Information System (INIS)

Arnott, D.

1985-01-01

The effects of background radiation, whether natural or caused by man's activities, are discussed. The known biological effects of radiation in causing cancers or genetic mutations are explained. The statement that there is a threshold below which there is no risk is examined critically. (U.K.)

Natural background levels and threshold values of chemical species in three large-scale groundwater bodies in Northern Italy

International Nuclear Information System (INIS)

Molinari, Antonio; Guadagnini, Laura; Marcaccio, Marco; Guadagnini, Alberto

2012-01-01

We analyze natural background levels (NBLs) and threshold values (TVs) of spatially distributed chemical species (NH 4 , B and As) which may be a potential pressure and concern in three large scale alluvial and fluvio-deltaic aquifers at different depths of the Apennines and Po river plains in Emilia–Romagna, Northern Italy. Our results are based on statistical methodologies designed to separate the natural and anthropogenic contributions in monitored concentrations by modeling the empirical distribution of the detected concentration with a mixture of probability density functions. Available chemical observations are taken over a 20 years period and are associated with different depths and cover planar investigation scales of the order of hundreds of kilometers. High concentration values detected for NH 4 and B appear to be related to high natural background levels. Due to interaction with the host rock in different geochemical environments we observed that concentration vary in time and space (including in depth) consistently with the hydrogeochemical features and the occurrence of natural attenuation mechanisms in the analyzed reservoirs. Conversely, estimated As NBLs are not consistent with the conceptual model of the hydrogeochemical behavior of the systems analyzed and experimental evidences of As content in aquifer cores. This is due to the inability of these techniques to incorporate the complex dynamics of the processes associated with the specific hydrogeochemical setting. Statistical analyses performed upon aggregating the concentration data according to different time observation windows allow identifying temporal dynamics of NBLs and TVs of target compounds within the observation time frame. Our results highlight the benefit of a dynamic monitoring process and analysis of well demarcated groundwater bodies to update the associated NBLs as a function of the temporal dependence of natural processes occurring in the subsurface. Monitoring protocols could

Ionizing radiation and a wood-based biorefinery

International Nuclear Information System (INIS)

Driscoll, Mark S.; Stipanovic, Arthur J.; Cheng, Kun; Barber, Vincent A.; Manning, Mellony; Smith, Jennifer L.; Sundar, Smith

2014-01-01

Woody biomass is widely available around the world. Cellulose is the major structural component of woody biomass and is the most abundant polymer synthesized by nature, with hemicellulose and lignin being second and third. Despite this great abundance, woody biomass has seen limited application outside of the paper and lumber industries. Its use as a feedstock for fuels and chemicals has been limited because of its highly crystalline structure, inaccessible morphology, and limited solubility (recalcitrance). Any economic use of woody biomass for the production of fuels and chemicals requires a “pretreatment” process to enhance the accessibility of the biomass to enzymes and/or chemical reagents. Electron beams (EB), X-rays, and gamma rays produce ions in a material which can then initiate chemical reactions and cleavage of chemical bonds. Such ionizing radiation predominantly scissions and degrades or depolymerizes both cellulose and hemicelluloses, less is known about its effects on lignin. This paper discusses how ionizing radiation can be used to make a wood-based biorefinery more environmentally friendly and profitable for its operators. - Highlights: • Ionizing radiation reduces the crystallinity of cellulose. • Ionizing radiation reduces cellulose's degree of polymerization. • The amount and rate of enzymatic hydrolysis of lignocellulosic materials, including wood, are increased with increasing radiation dose. • Wood and other lignocellulosic materials have the potential to be a renewable material for the production of chemicals and fuels

Dosimetry methods for the estimation of exposure to ionizing radiation

International Nuclear Information System (INIS)

Lopez Bejarano, Gladys

2012-01-01

Ionizing radiations, by their nature, have required for their detection the use of suitable devices generically referred detecting systems. The detection of secondary particles arising during the processes of ionization and excitation to the passage of radiation in the environment, have constituted the basis of the measurement methods. A detector system is a device that converts the energy of the incident radiation on a signal (electrical, photochemical, etc.) that is easily processable from the technological point of view, but without distorting the original information. These devices have provided qualitative or quantitative information about the radiation of interest. The detector system is a set of a detector together with a processing system. This system has based its operation in methods of: gas ionization, scintillation, semiconductor, film, thermoluminescence, among others. (author) [es

Multiphoton Ionization Detection in Collinear Laser Spectroscopy of Isolde Beams

CERN Multimedia

2002-01-01

The experiments using the multiphoton ionization technique have been continued in the beginning of 1990 with stable beam tests on the modified apparatus and with another radioactive beam time on Yb. Higher laser power and an increased vacuum in the ionization region (see figure) yielded a further gain in sensitivity, mainly due to the better suppression of the background ions produced in rest gas collisions. For even Yb isotopes we have now reached a detection efficiency of $\\epsilon$~=~1~x~10$^{-5}$ ions per incoming atom at a background count rate of 30~ions from a beam of 5~x~10$^9$. This sensitivity was high enough for spectroscopy on $^{157}$Yb, where the typical ISOLDE yield of 5~x~10$^7$Yb ions is covered by an isobaric contamination of more than 10$^{10}$ ions. Measurements have also been performed on $^{175}$Yb. These give the first precise value for the magnetic moment of this isotope, $\\mu$~=~0.766(8)$ mu _{N} $, which agrees rather well with the magnetic moment of the isotone $^{177}$Hf. The isoto...

Ionization

International Nuclear Information System (INIS)

2002-01-01

This document reprints the text of the French by-law from January 8, 2002 relative to the approval and to the controls and verifications of facilities devoted to the ionizing of food products for human beings and animals. The by-law imposes the operators of such facilities to perform measurements and dosimetric verifications all along the ionization process. (J.S.)

Ionizing radiation

International Nuclear Information System (INIS)

Kruger, J.

1989-01-01

Ionizing radiation results in biological damage that differs from other hazardous substances and is highly dangerous to man. Ionizing radiation cannot be perceived by man's sense organs and the biological damage cannot be detected immediately afterwards (except in very high doses). Every human being is exposed to low doses of radiation. The structure of the atom; sources of ionizing radiation; radiation units; biological effects; norms for radiation protection; and the national control in South Africa are discussed. 1 fig., 5 refs

Field ionization mass spectrometry (FIMS) applied to tracer studies and isotope dilution analysis

International Nuclear Information System (INIS)

Anbar, M.; Heck, H.d'A.; McReynolds, J.H.; St John, G.A.

1975-01-01

The nonfragmenting nature of field ionization mass spectrometry makes it a preferred technique for the isotopic analysis of multilabeled organic compounds. The possibility of field ionization of nonvolatile thermolabile materials significantly extends the potential uses of this technique beyond those of conventional ionization methods. Multilabeled tracers may be studied in biological systems with a sensitivity comparable to that of radioactive tracers. Isotope dilution analysis may be performed reliably by this technique down to picogram levels. These techniques will be illustrated by a number of current studies using multilabeled metabolites and drugs. The scope and limitations of the methodology are discussed

Electron ionization and the Compton effect in double ionization of helium

International Nuclear Information System (INIS)

Samson, J.

1994-01-01

The author discusses ionization phenomena in helium, both photoionization and electron ionization. In particular he compares double ionization cross sections with total cross sections, as a function of electron energy, and photon energy. Data is discussed over the energy range up to 10 keV

Development of a sodium ionization detector for sodium-to-gas leaks

International Nuclear Information System (INIS)

Swaminathan, K.; Elumalai, G.

1984-01-01

A sensitive sodium-to-gas leak detector has been indigenously developed for use in liquid metal cooled fast breeder reactor. The detector relies on the relative ease with which sodium vapour or its aerosols including its oxides and hydroxides can be thermally ionized compared with other possible constituents such as nitrogen, oxygen, water vapour etc. in a carrier gas and is therefore called sodium ionization detector (SID). The ionization current is a measure of sodium concentration in the carrier gas sampled through the detector. Different sensor designs using platinum and rhodium as filament materials in varying sizes were constructed and their responses to different sodium aerosol concentrations in the carrier gas were investigated. Nitrogen was used as the carrier gas. Both the background current and speed of response were found to depend on the diameter of the filament. There was also a particular collector voltage which yielded maximum sensitivity of the detector. The sensor was therefore optimised considering influence of above factors and a detector has been built which demonstrates a sensitivity better than 0.3 nanogram of sodium per cubic centimetre of carrier gas for a signal to background ratio of 1:1. Its usefulness in detecting sodium fires in experimental area was also demonstrated. Currently efforts are under way to improve the life time of the filament used in the above detector. (author)

Ionizing radiations

International Nuclear Information System (INIS)

2009-01-01

After having recalled some fundamental notions and measurement units related to ionizing radiations, this document describes various aspects of natural and occupational exposures: exposure modes and sources, exposure levels, biological effects, health impacts. Then, it presents prevention principles aimed at, in an occupational context of use of radiation sources (nuclear industry excluded), reducing and managing these exposures: risk assessment, implementation of safety from the front end. Some practical cases illustrate the radiation protection approach. The legal and regulatory framework is presented: general notions, worker exposure, measures specific to some worker categories (pregnant and breast feeding women, young workers, temporary workers). A last part describes what is to be done in case of incident or accident (dissemination of radioactive substances from unsealed sources, anomaly occurring when using a generator or a sealed source, post-accident situation)

Relationship between ionized calcium and serum albumin level in children with idiopathic nephrotic syndrome

Directory of Open Access Journals (Sweden)

Viiola Irene Winata

2016-10-01

Full Text Available Background Nephrotic syndrome (NS patients frequently have abnormalities in calcium metabolism that manifest as hypocalcemia and reduced intestinal absorption of calcium. Hypocalcemia is initially attributed to hypoalbuminemia but it may also relate to a low level of ionized calcium. The ionized calcium level depends on the severity and duration of proteinuria. Objective To assess the rel ationship between ionized calcium and serum albumin level in idiopathic NS children. Methods An analytical study with cross-sectional design was applied to NS and healthy children between 1-14 years old in the Child Health Department of Hasan Sadikin Hospital, Bandung from December 2009 to April 2010. Ionized calcium was examined by Ca2 + analyzer AVL 980 with ion-selective electrodes (ISE methods. Results A total of34 subjects were recruited, consist of 17 NS and 17 healthy children. The mean ionized calcium and serum albumin level in NS children was 4.56 (SD 0.23 mg/dLand 1.45 (SD 0.24 g/dL, respectively. Statistical difference between ionized calcium level in NS and in healthy children was significant (P<0.05. Pearson correlation test between ionized calcium and serum albumin was significant (P<0.05 with correlation coefficient (r 0.53. We found the following equation to estimate ionized calcium (y based on the serum albumin level (x: y=3.84+0.49x. Conclusion There is a moderately positive linear relationship between ionized calcium and serum albumin level in NS children.

Mode shape and natural frequency identification for seismic analysis from background vibration

International Nuclear Information System (INIS)

Bhan, S.; Wozniak, Z.

1986-10-01

Background vibration in a CANDU plant can be used to determine the dynamic characteristics of major items of equipment, such as calandria, the fuelling machines and the primary heat transport pumps. These dynamic characteristics can then be used to verify the seismic response of the equipment which, at present, is based on theoretical models only. The feasibility and basic theory of this new approach (which uses accelerations measured at several points on a structure and does not require knowledge of the source of excitation) was established in Phase I of the study. This report is based on Phase II in which the methods of analysis developed in Phase I were improved and verified experimentally. A Fast Fourier Transform (FFT) algorithm was incorporated and an interactive curve fitting technique was developed to obtain the dynamic characteristics in the form of natural frequencies, mode shapes and damping ratios. The method is now available for use at a CANDU plant

Ionization detector

International Nuclear Information System (INIS)

Solomon, E.E.

1980-01-01

A safe and reliable apparatus for detecting products of combustion and aerosols in the atmosphere was developed which uses a beta source. It is easy to adjust for optimum performance. The ionization detector comprises a double chamber; one of the chambers is the basic sensing chamber. The sensing chamber is ported to both the secondary chambers to account for slow ambient changes in the atmosphere outside of the chamber. The voltages from the ionization chamber are adjusted with electrodes in each chamber. The ionization chamber contains baffles to direct the air to be sensed as well as an electrostatic screen. A unique electronic circuit provides an inexpensive and reliable means for detecting the signal change which occurs in the ionization chamber. The decision level of the alarm circuit can be adjusted to allow for any desired sensitivity. (D.N.)

Low environmental radiation background impairs biological defence of the yeast Saccharomyces cerevisiae to chemical radiomimetic agents

International Nuclear Information System (INIS)

Satta, L.; Augusti-Tocco, G.; Ceccarelli, R.; Paggi, P.; Scarsella, G.; Esposito, A.; Fiore, M.; Poggesi, I.; Ricordy, R.; Cundari, E.

1995-01-01

Background radiation is likely to constitute one of the factors involved in biological evolution since radiations are able to affect biological processes. Therefore, it is possible to hypothesize that organisms are adapted to environmental background radiation and that this adaptation could increase their ability to respond to the harmful effects of ionizing radiations. In fact, adaptive responses to alkylating agents and to low doses of ionizing radiation have been found in many organisms. In order to test for effects of adaptation, cell susceptibility to treatments with high doses of radiomimetic chemical agents has been studied by growing them in a reduced environmental radiation background. The experiment has been performed by culturing yeast cells (Saccharomyces cerevisiae D7) in parallel in a standard background environment and in the underground Gran Sasso National Laboratory, with reduced environmental background radiation. After a conditioning period, yeast cells were exposed to recombinogenic doses of methyl methanesulfonate. The yeast cells grown in the Gran Sasso Laboratory showed a higher frequency of radiomimetic induced recombination as compared to those grown in the standard environment. This suggests that environmental radiation may act as a conditioning agent

REQUIREMENTS TO THE LIMITATION OF POPULATION EXPO-SURE FROM THE NATIRAL IONIZING IRRADIATION SOURCES IN INDUSTRIAL CONDITIONS

Directory of Open Access Journals (Sweden)

I. P. Stamat

2010-01-01

Full Text Available The paper presents conceptually new requirements to the limitation of population exposure from the natural ionizing irradiation sources in industrial conditions, introduced into Basic Sanitary Rules of Radiation Safety (OSPORB-99/2010. It is shown that, first of all, introduction of these requirements is aimed at the resolution of variety of previously existing serious contradictions in organization of radiation safety control and supervision for the impact of natural ionizing irradiation sources in industry.

Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

International Nuclear Information System (INIS)

Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B; Friedman, A.F.; Lee, E.P.

2009-01-01

Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

Quantification of DNA repair capacity (DRC) in peripheral blood lymphocytes of individuals from natural high background radiation areas of Kerala, India

International Nuclear Information System (INIS)

Vivek Kumar, P.R.; Seshadri, M.

2011-01-01

Human populations residing in the coastal areas of Kerala from Neendakara in south to Purakkad in north receive high level natural background radiation primarily due to the presence of thorium ( 232 Th) in the monazite containing beach sand. This provides a unique opportunity to investigate the health effects of natural high level radiation on humans. Earlier studies from our laboratory in newborns for incidence of congenital malformations, structural and numerical chromosome aberrations failed to show any significant health or biological effects due to high level natural radiation exposure. The current study used alkaline single cell gel electrophoresis (comet) assay due to its sensitivity, speed, flexibility and low cost. Biological effects of low level natural radiation was studied by assessing individual's DNA Repair Capacity (DRC), which is essential for maintaining the genome integrity. DNA damage was estimated in terms of DNA strand breaks per million base pairs (SB/106 bp). In our earlier study using comet assay, DNA SBs increased with age in subjects from normal background radiation area (NBRA). However, significant inverse correlation was observed in subjects from high background radiation area (HBRA). Further, spontaneous DNA SBs in elderly subjects (? 41 years) from HBRA was significantly lower compared to the subjects from NBRA. The present study was carried out in 90 healthy adult male subjects of which, 63 subjects belonged to HBRA and 27 subjects from NBRA. The annual effective dose in HBRA subjects was 5.87 ± 4.17 mSv year-1 (Mean ± S.D., range 1.07-17.41) and in NBRA subjects was ? 1mSv year-1. Peripheral blood lymphocytes from these individuals were irradiated with 4Gy of 60 Co gamma rays (1.4Gy/minute, Low dose irradiator 2000, BRIT, India) and DNA repair was assessed at 30 minutes. As the results were not normally distributed, the data were log transformed to normalize variance. Regression analysis was carried out to determine the relative

Bilogical effects of ionizing radiation: epidemiological surveys and laboratory animal experiments. Implications for risk evaluation and decision processes

International Nuclear Information System (INIS)

Fabrikant, J.I.

1981-04-01

General background is given for an understanding of the potential health effects in populations exposed to low-level ionizing radiations. The discussion is within the framework of the scientific deliberations and controversies that arose during preparation of the current report of the committee on the biological effects of ionizing radiation of the National Academy of Science - National Research Council (1980 Beir-III Report)

Natural indoor gamma background in an urban environment of Southern Poland

International Nuclear Information System (INIS)

Koperski, J.

1984-01-01

A regional survey of indoor exposure to natural gamma background from terrestrial sources was performed in the urban environment of six administrative provinces of Southern Poland. 1351 dwelling houses at 144 localities were monitored using of LiF:Mg,Ti thermoluminescence dosemeters. The dose rates observed indoors were between 32 and 185 nGy.h -1 and were strongly dependent on the types of building materials used in the dwellings monitored. The highest mean provincial values were found in slag and fly-ash dwellings (77-123 nGy.h -1 ), while in wooden dwellings these values were the lowest (42-51 nGy.h -1 ). Intermediate values occurred in clay brick dwellings (57-102 nGy.h -1 ), in dwellings of mixed, wooden-brick construction (60-79 nGy,h -1 ) and in dwellings made of gravel-sand prefabricates (52-68 nGy.h -1 ). The calculated mean annual per capita effective dose equivalent rates ranged between 0.2 mSv.y -1 , for the inhabitants of wooden houses, and 0.6 mSv.y -1 for those living in houses made of coal by-product prefabricates. (author)

Barium Tagging from nEXO Using Resonance Ionization Spectroscopy

Science.gov (United States)

Twelker, K.; Kravitz, S.

nEXO is a 5-ton liquid enriched-xenon time projection chamber (TPC) to search for neutrinoless double-beta decay, designed to have the sensitivity to completely probe the inverted mass hierarchy of Majorana neutrinos. The detector will accommodate-as a background reduction technique-a system to recover and identify the barium decay product. This upgrade will allow a background-free measurement of neutrinoless double-beta decay and increase the half-life sensitivity of the experiment by at least one order of magnitude. Ongoing research and development includes a system to test barium extraction from liquid xenon using surface adsorption and Resonance Ionization Spectroscopy (RIS).

Low energy background radiation in India

International Nuclear Information System (INIS)

Gopinath, D.V.

1980-01-01

Spectral distribution of background radiation at 9 locations spread all over India has been measured. Specifications of the counting set-up standardised for measurement are given. At one of the places, the background spectrum was measured with four different types of detectors. A broad peak in 60-100 keV with differing intensity and standard deviation is observed in all the spectra. In the Kalpakkam area, the peak near the seashore is observed to be more intense than away from the shore. This could be due to the presence of monazite sands on the seashore. The natural background radiation is observed to have a steep rise below 20 keV. Peak intensity is found to be independent of both the location (i.e. the source of energy) and the type of detector used for measurement. The calculated spectra due to multiple scattered radiation (with a nominal source energy of 1 MeV) through paraffin wax and the measured background spectrum with the detector shielded with 20 cm wax show good agreement above 40 keV. This shows that 80 keV hump in the natural background radiation is a property of air. The peak, therefore, in the spectra of natural background radiation is essentially a property of medium and it is independent of location or detector. (M.G.B.)

Effects of ionizing radiation on the immune system

International Nuclear Information System (INIS)

Dubois, J.B.

1986-01-01

After reviewing the different lymphoid organs and the essential phases of the immune response, we studied the morphological and functional effects of ionizing radiation on the immunological system. Histologic changes in the lymph nodes, spleen, thymus, and different lymphocyte subpopulations were studied in relation with the radiation dose and irradiated volume (whole body irradiation, localized irradiation). Functional changes in the immune system induced by ionizing radiation were also investigated by a study of humoral-mediated immunity (antibody formation) and cell-mediated immunity (behavior of macrophages, B-cells, T suppressor cells, T helper cells, T effector cells, and natural killer cells). A study into the mechanisms of action of ionizing radiation and the immune processes it interferes with suggests several likely hypotheses (direct action on the immune cells, on their precursors, on seric mediators or on cell mediators). The effects on cancer patients' immune reactions of low radiation doses delivered to the various lymphoid organs are discussed, as well as the relationships between the host and the evolution of the tumor [fr

Current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization

International Nuclear Information System (INIS)

Stoyanov, D G

2007-01-01

The balances of particles and charges in the volume of parallel-plane ionization chamber are considered. Differential equations describing the distribution of current densities in the chamber volume are obtained. As a result of the differential equations solution an analytical form of the current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization in the volume is obtained

Current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization

Energy Technology Data Exchange (ETDEWEB)

Stoyanov, D G [Faculty of Engineering and Pedagogy in Sliven, Technical University of Sofia, 59, Bourgasko Shaussee Blvd, 8800 Sliven (Bulgaria)

2007-08-15

The balances of particles and charges in the volume of parallel-plane ionization chamber are considered. Differential equations describing the distribution of current densities in the chamber volume are obtained. As a result of the differential equations solution an analytical form of the current-voltage characteristic of parallel-plane ionization chamber with inhomogeneous ionization in the volume is obtained.

Natural background levels and threshold values of chemical species in three large-scale groundwater bodies in Northern Italy

Energy Technology Data Exchange (ETDEWEB)

Molinari, Antonio, E-mail: ant.molinari2002@libero.it [Politecnico di Milano, Dipartimento di Ingegneria Idraulica, Ambientale, Infrastrutture Viarie e Rilevamento, Piazza L. Da Vinci, 32-20133 Milano (Italy); Guadagnini, Laura [Politecnico di Milano, Dipartimento di Ingegneria Idraulica, Ambientale, Infrastrutture Viarie e Rilevamento, Piazza L. Da Vinci, 32-20133 Milano (Italy); Marcaccio, Marco [ARPA Emilia-Romagna, Direzione Tecnica, Largo Caduti del Lavoro, 6-40122 Bologna (Italy); Guadagnini, Alberto [Politecnico di Milano, Dipartimento di Ingegneria Idraulica, Ambientale, Infrastrutture Viarie e Rilevamento, Piazza L. Da Vinci, 32-20133 Milano (Italy)

2012-05-15

We analyze natural background levels (NBLs) and threshold values (TVs) of spatially distributed chemical species (NH{sub 4}, B and As) which may be a potential pressure and concern in three large scale alluvial and fluvio-deltaic aquifers at different depths of the Apennines and Po river plains in Emilia-Romagna, Northern Italy. Our results are based on statistical methodologies designed to separate the natural and anthropogenic contributions in monitored concentrations by modeling the empirical distribution of the detected concentration with a mixture of probability density functions. Available chemical observations are taken over a 20 years period and are associated with different depths and cover planar investigation scales of the order of hundreds of kilometers. High concentration values detected for NH{sub 4} and B appear to be related to high natural background levels. Due to interaction with the host rock in different geochemical environments we observed that concentration vary in time and space (including in depth) consistently with the hydrogeochemical features and the occurrence of natural attenuation mechanisms in the analyzed reservoirs. Conversely, estimated As NBLs are not consistent with the conceptual model of the hydrogeochemical behavior of the systems analyzed and experimental evidences of As content in aquifer cores. This is due to the inability of these techniques to incorporate the complex dynamics of the processes associated with the specific hydrogeochemical setting. Statistical analyses performed upon aggregating the concentration data according to different time observation windows allow identifying temporal dynamics of NBLs and TVs of target compounds within the observation time frame. Our results highlight the benefit of a dynamic monitoring process and analysis of well demarcated groundwater bodies to update the associated NBLs as a function of the temporal dependence of natural processes occurring in the subsurface. Monitoring

Chemical protection against ionizing radiation

International Nuclear Information System (INIS)

Livesey, J.C.; Reed, D.J.

1987-01-01

Over 40 years have passed since the research of the Manhattan Project suggested the possibility of chemical protection against ionizing radiation. During that time, much has been learned about the nature of radiation-induced injury and the factors governing the expression of that injury. Thousands of compounds have been tested for radioprotective efficacy, and numerous theories have been proposed to account for these actions. The literature on chemical radioprotection is large. In this article, the authors consider several of the mechanisms by which chemicals may protect against radiation injury. They have chosen to accent this view of radioprotector research as opposed to that research geared toward developing specific molecules as protective agents because they feel that such an approach is more beneficial in stimulating research of general applicability. This paper describes the matrix of biological factors upon which an exogenous radioprotector is superimposed, and examines evidence for and against various mechanisms by which these agents may protect biological systems against ionizing radiation. It concludes with a brief outlook for research in chemical radioprotection

IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

International Nuclear Information System (INIS)

Stark, C. R.; Helling, Ch.; Rimmer, P. B.; Diver, D. A.

2013-01-01

Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10 –7 ) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10 –6 -1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H 2 , or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks

Space Flight Ionizing Radiation Environments

Science.gov (United States)

Koontz, Steve

2017-01-01

The space-flight ionizing radiation (IR) environment is dominated by very high-kinetic energy-charged particles with relatively smaller contributions from X-rays and gamma rays. The Earth's surface IR environment is not dominated by the natural radioisotope decay processes. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of space radiation environments, beginning with the space radiation environment on the International Space Station and moving outward through the Van Allen belts to cislunar space. The benefits and limitations of radiation shielding materials will also be summarized.

Ionizing gas breakdown waves in strong electric fields.

Science.gov (United States)

Klingbeil, R.; Tidman, D. A.; Fernsler, R. F.

1972-01-01

A previous analysis by Albright and Tidman (1972) of the structure of an ionizing potential wave driven through a dense gas by a strong electric field is extended to include atomic structure details of the background atoms and radiative effects, especially, photoionization. It is found that photoionization plays an important role in avalanche propagation. Velocities, electron densities, and temperatures are presented as a function of electric field for both negative and positive breakdown waves in nitrogen.

Generation of low-energy muons with laser resonant ionization

International Nuclear Information System (INIS)

Matsuda, Y.; Bakule, P.; Iwasaki, M.; Matsuzaki, T.; Miyake, Y.; Ikedo, Y.; Strasser, P.; Shimomura, K.; Makimura, S.; Nagamine, K.

2006-01-01

We have constructed a low-energy muSR spectrometer at RIKEN-RAL muon facility in ISIS, the UK. With low-background of pulsed muon beam, and short pulse width from laser resonant ionization method, it is hoped this instrument will open new possibilities for studies of material sciences with muon beam. It is enphasized that this method is well suited to the facility where intense pulsed proton beam is available

Biological Effects of Ionizing Radiation

Science.gov (United States)

Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

1952-04-07

This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

Ionization chambers

International Nuclear Information System (INIS)

Boag, J.W.

1987-01-01

Although a variety of solid-state and chemical methods for measuring radiation dose have been developed in recent decades and calorimetry can now provide an absolute standard of reference, ionization dosimetry retains its position as the most widely used, most convenient, and, in most situations, most accurate method of measuring either exposure or absorbed dose. The ionization chamber itself is the central element in this system of dosimetry. In this chapter the principles governing the construction and operation of ionization chambers of various types are examined. Since the ionization chambers now in general use are nearly all of commercial manufacture, the emphasis is on operating characteristics and interpretation of measurements rather than on details of construction, although some knowledge of the latter is often required when applying necessary corrections to the measured quantities. Examples are given of the construction of typical chambers designed for particular purposes, and the methods of calibrating them are discussed

The ionizing treatment of food

International Nuclear Information System (INIS)

1998-01-01

This book of proceedings contains the talks given by the members of the Society of chemical experts of France (SECF) and by various specialists of the ionizing treatment during the scientific days of September 25-26, 1997. The aim of this meeting was to reconsider the effects of ionization from a scientific point of view and apart from the polemics generated by this domain. The following topics were discussed successively: source and characterization of a ionizing treatment, biological effects of ionization on food and the expected consequences, the ionizing treatment and the reduction of the vitamin C content of fruits and vegetables, is it safe to eat irradiated food?, the organoleptic modifications of food after ionization, quality assurance of dosimetry measurements in an industrial installation of food ionization, the French and European regulations in food ionization, the detection of irradiated foodstuffs, processed food and complex lipid matrices, sterilization of dishes for immuno-depressed patients using ionization. (J.S.)

Silver nanostructures in laser desorption/ionization mass spectrometry and mass spectrometry imaging.

Science.gov (United States)

Sekuła, Justyna; Nizioł, Joanna; Rode, Wojciech; Ruman, Tomasz

2015-09-21

Silver nanoparticles have been successfully applied as a matrix replacement for the laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF-MS). Nanoparticles, producing spectra with highly reduced chemical background in the low m/z region, are perfectly suited for low-molecular weight compound analysis and imaging. Silver nanoparticles (AgNPs) can efficiently absorb ultraviolet laser radiation, transfer energy to the analyte and promote analyte desorption, but also constitute a source of silver ions suitable for analyte cationisation. This review provides an overview of the literature on silver nanomaterials as non-conventional desorption and ionization promoters in LDI-MS and mass spectrometry imaging.

The French Central Service for Protection against ionizing radiations (SCPRI), its activity

International Nuclear Information System (INIS)

Pellerin, P.; Moroni, J.P.

1979-01-01

The French Central Service for Protection against Ionizing Radiations (SCPRI), a service of Public Health and Labour departments, is entrusted by the French radioprotection regulations, of the control on a national scale, of all activities involving the use of ionizing radiations. It uses on this purpose, 4000 square meters of laboratories equiped with important radioanalyze and counting facilities (among them, a 100 low background β counters room). The SCPRI has also been nominated by WHO, as International Reference Center for radioactivy measurements in the environment. These duties have led the SCPRI to develop a drastic quality control of the techniques of preparation and verification of standard sources and reference samples [fr

'Saddle-point' ionization

International Nuclear Information System (INIS)

Gay, T.J.; Hale, E.B.; Irby, V.D.; Olson, R.E.; Missouri Univ., Rolla; Berry, H.G.

1988-01-01

We have studied the ionization of rare gases by protons at intermediate energies, i.e., energies at which the velocities of the proton and the target-gas valence electrons are comparable. A significant channel for electron production in the forward direction is shown to be 'saddle-point' ionization, in which electrons are stranded on or near the saddle-point of electric potential between the receding projectile and the ionized target. Such electrons yield characteristic energy spectra, and contribute significantly to forward-electron-production cross sections. Classical trajectory Monte Carlo calculations are found to provide qualitative agreement with our measurements and the earlier measurements of Rudd and coworkers, and reproduce, in detail, the features of the general ionization spectra. (orig.)

Heating and ionization in MHD shock waves propagating into partially ionized plasma

International Nuclear Information System (INIS)

Bighel, L.; Collins, A.R.; Cramer, N.F.; Watson-Munro, C.N.

1975-09-01

A model of the structure of MHD switch-on shocks propagating in a partially ionized plasma, in which the primary dissipation mechanism is friction between ions and neutrals, is here compared favourably with experimental results. Four degrees of upstream ionization were studied, ranging from almost complete to very small ionization. (author)

Heating and ionization in MHD shock wave propagating into partially ionized plasma

International Nuclear Information System (INIS)

Bighel, L.; Collins, A.R.; Cramer, N.F.; Watson-Munro, C.N.

1975-09-01

A model of the structure of MHD switch-on shocks propagating in a partially ionized plasma, in which the primary dissipation mechanism is friction between ions and neutrals, is here compared favourably with experimental results. Four degrees of upstream ionization were studied, ranging from almost complete to very small ionization. (author)

Five-photon ionization of atomic hydrogen at wavelengths around the threshold for four-photon ionization

International Nuclear Information System (INIS)

Gontier, Y.; Trahin, M.; Wolff-Rottke, B.; Rottke, H.; Welge, K.H.; Feldmann, D.

1992-01-01

Theoretical and experimental studies show the strong influence of the three-photon nearly resonant 2p state on four- and five-photon ionization of atomic hydrogen near the threshold for four-photon ionization. Changes in five-photon ionization occur when the four-photon ionization channel opens. The angular distributions of photoelectrons from five-photon ionization of H are studied at five wavelengths which cover the range from four-photon resonance with high-lying Rydberg states (n≥10) to direct four-photon ionization into the continuum. The role of resonances in this ionization process is discussed. A fair agreement is found in comparing experimental and theoretical results

Equipment for handling ionization chamber

International Nuclear Information System (INIS)

Altmann, J.

1988-01-01

The device consists of an ionization channel with an ionization chamber, of a support ring, axial and radial bearings, a sleeve, a screw gear and an electric motor. The ionization chamber is freely placed on the bottom of the ionization channel. The bottom part of the channel deviates from the vertical axis. The support ring propped against the axial bearing in the sleeve is firmly fixed to the top part of the ionization channel. The sleeve is fixed to the reactor lid. Its bottom part is provided with a recess for the radial bearing which is propped against a screw wheel firmly connected to the ionization channel. In measuring neutron flux, the screw wheel is rotated by the motor, thus rotating the whole ionization channel such that the ionization chamber is displaced into the reactor core.(J.B.). 1 fig

Criteria for radiological protection against exposure to natural radiation

International Nuclear Information System (INIS)

Cardenas Herrera, Juan

2012-01-01

Ionizing radiation includes natural radiation which has been part cosmic radiation. Radon in homes, irradiation, gamma, among others, they have also been part of ionizing radiation. The activities that have lead to natural radiation materials are: mining and processing of uranium, radio application and thorium, phosphate industry, mining and smelting of metals, oil and gas extraction, coal mining and power generation, rare earth industry and titanium, zirconium and ceramics, building materials, waste water purification. Therefore, different criteria for radiation protection have had to create against exposure to natural radiation. Distinct rules and regulations to control were created in that sense [es

Foodstuffs preservation by ionization

International Nuclear Information System (INIS)

1991-12-01

This document contains all the papers presented at the meeting on foodstuffs preservation by ionization. These papers deal especially with the food ionization process, its development and the view of the food industry on ionization. Refs and figs (F.M.)

Concerns on the health effects of low-dose ionizing radiations from naturally occurring radioactive materials (NORM)

International Nuclear Information System (INIS)

Mohankumar, Mary N.

2005-01-01

It is a widely known fact that man evolved in a naturally radioactive environment. Even today life exists in an atmosphere of cosmic and terrestrial radiation. Radionuclides are found naturally in air, water and soil. They are even found in us, we being the products of our environment. Every day, we ingest and inhale radionuclides in our air and food and the water. Natural radioactivity is common in the rocks and soil that makes up our planet, in water and oceans, and in our building materials and homes. There is nowhere on earth that one cannot find natural radioactivity. Radioactive materials which occur naturally and expose people to radiation occur widely, and are known by the acronym 'NORM' (Naturally Occurring Radioactive Materials). Besides, around the globe there are some areas with an elevated background radiation. These areas include parts of Brazil, Iran, India and China. The sources of radiation in these areas include monazite containing beach sands and radium from hot springs. On the southwest coast of India, there are large deposits of thorium bearing monazite sands that contribute to an external radiation dose of about 5 - 6 mGy/yr, but in some parts doses up to 32.6 mGy/yr have been reported. Nevertheless, most general public associate ionising radiations only with the nuclear industry. Antinuclear activists often fail to accept the fact that coal-fired power stations and the oil and gas exploration operations may emit more radioactivity than an operating nuclear reactor. Another NORM issue relates to radon exposure in homes, particularly those built on granite grounds. The solid airborne Rn-222 progeny, particularly Po-218, Pb-214 and Bi-214 are of health importance because they can be inspired and retained in the lung causing cancer. Man-made operations like oil and gas production and processing operations result in technologically enhanced naturally occurring radioactive materials (TENORM) to accumulate at elevated concentrations in by

Dereplication of Microbial Natural Products by LC-DAD-TOFMS

DEFF Research Database (Denmark)

Nielsen, Kristian Fog; Månsson, Maria; Rank, Christian

2011-01-01

Dereplication, the rapid identification of known compounds present in a mixture, is crucial to the fast discovery of novel natural products. Determining the elemental composition of compounds in mixtures and tentatively identifying natural products using MS/MS and UV/vis spectra is becoming easier...... with advances in analytical equipment and better compound databases. Here we demonstrate the use of LC-UV/vis-MS-based dereplication using data from UV/vis diode array detection and ESI+/ESI– time-of-flight MS for assignment of 719 microbial natural product and mycotoxin reference standards. ESI+ was the most...... unambiguously using multiple adduct ions, while a further 41% of the compounds were detected only as [M – H]−. The most reliable interpretations of conflicting ESI+ and ESI– data on a chromatographic peak were from the ionization polarity with the most intense ionization. Poor ionization was most common...

Cytological and histological changes in lymphocytes influence of ionizing radiation on health workers

OpenAIRE

Gorgieva, Pale; Nedeljkovik, Bojana; Velickova, Nevenka

2014-01-01

Introduction: Ionizing radiation can originate from natural and artificial sources and ionization may be direct or indirect. Depending on the dose and intensity of radiation radiobiological effect may be different. Acute radiation sickness occurs as a result of irradiation of the whole body with large doses of radiation in a short time. While chronic radiation damages arise in professional workers due to exposure to small doses over a long time. Depending on the type of tissue and cell proper...

Ambient ionization mass spectrometry: A tutorial

Energy Technology Data Exchange (ETDEWEB)

Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Shiea, Jentaie, E-mail: jetea@fac.nsysu.edu.tw [Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Cancer Center, Kaohsiung Medical University, Kaohsiung, Taiwan (China)

2011-09-19

Highlights: {yields} Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. {yields} We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. {yields} The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

Ambient ionization mass spectrometry: A tutorial

International Nuclear Information System (INIS)

Huang, Min-Zong; Cheng, Sy-Chi; Cho, Yi-Tzu; Shiea, Jentaie

2011-01-01

Highlights: → Ambient ionization technique allows the direct analysis of sample surfaces with little or no sample pretreatment. → We sort ambient ionization techniques into three main analytical strategies, direct ionization, direct desorption/ionization, and two-step ionization. → The underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques are described and compared. - Abstract: Ambient ionization is a set of mass spectrometric ionization techniques performed under ambient conditions that allows the direct analysis of sample surfaces with little or no sample pretreatment. Using combinations of different types of sample introduction systems and ionization methods, several novel techniques have been developed over the last few years with many applications (e.g., food safety screening; detection of pharmaceuticals and drug abuse; monitoring of environmental pollutants; detection of explosives for antiterrorism and forensics; characterization of biological compounds for proteomics and metabolomics; molecular imaging analysis; and monitoring chemical and biochemical reactions). Electrospray ionization and atmospheric pressure chemical ionization are the two main ionization principles most commonly used in ambient ionization mass spectrometry. This tutorial paper provides a review of the publications related to ambient ionization techniques. We describe and compare the underlying principles of operation, ionization processes, detecting mass ranges, sensitivity, and representative applications of these techniques.

Relation between cancer incidence or mortality and external natural background radiation in Japan

International Nuclear Information System (INIS)

Ujeno, Y.

1983-01-01

Analysis was performed on the relationships between the organ dose-equivalent rate due to natural background radiation (mSv/a) and three parameters of cancer risk: the age-adjusted cancer incidence (patients x 10 5 persons x a -1 ) in 13 large areas, the standardized mortality ratio of cancers in 46 large areas, and the cancer mortality in the population aged more than 40 years old (cancer deaths x 10 5 persons x a -1 ) in 649 small areas. The age-adjusted liver cancer incidence in males fitted the exponential model significantly (p<0.01) and the relationship of stomach cancer mortality of aged males in small areas fitted the linear model significantly (p<0.05). No relationship was observed with regard to female cancer in either case. The relationships between the three parameters and various other cancers of both sexes were not statistically significant. (author)

Epidemiological studies in high-background radiation areas its potential contribution to evaluating risk of low-level radiation

International Nuclear Information System (INIS)

Akiba, Suminori; Nair, R.K.; Nakamura, Seiichi; Mizuno, Shoich

2008-01-01

The health effect of low-level ionizing radiation is yet unclear. As pointed out by Upton in his review (Upton, 1989), low-level ionizing radiation seems to have different biological effects from what high-level radiation has. Its evaluation requires epidemiological studies of scale-large cohorts (ICRP 99, 2005) such of atomic bomb survivors and nuclear workers. Epidemiological studies in high-background radiation (HBR) areas are also expected to make a significant contribution toward this end. Among several HBR areas in the world, Yangjiang, Guangdong Province in China, Karunagappally in Kerala State of India, Manawalakurichi and Koodankulam in Tamil Nadu of India, and Ramsar in Iran are important areas where epidemiological studies are possible, because of their relatively high background radiation levels and large population sizes. (author)

The management of workers occupationally exposed to ionizing radiation

International Nuclear Information System (INIS)

1993-10-01

In Canada, the regulation of radiation protection is a shared responsibility between the federal body (the Atomic Energy Control Board) and the appropriate provincial body (usually the Department of Health, or Department of Labour). The AECB is responsible, for example, for regulating the development, application and use of nuclear energy and radioisotopes, and the provinces are responsible for the regulation of all other forms of ionizing and non-ionizing radiations and for naturally-occurring radioactive material (NORM). Although there is consultation between the federal and provincial regulatory agencies, the division of jurisdictional authority has resulted in considerable differences in the approach towards implementation radiation protection programs in Canada. This is especially true in the management of workers occupationally exposed to ionizing radiation. These differences have produced unwarranted discrepancies in operating procedures and practices in the allocation of resources and manpower, and in the requirements governing radiological training, personnel monitoring and medical surveillance. In light of the General Amendments to the AEC Regulations, the 1990 Recommendations of the ICRP, and the IAEA recommendations on safety culture, the ACRP has considered it timely to undertake a study to examine the feasibility of establishing a more coherent approach to harmonize radiation protection practices within Canada. This study comprised an examination of the regulatory approach used in several countries: a review of the nature of radiation safety programs in various types of licensed institutions and facilities in Canada; and a review of recommendations of internationally-recognized authorities in radiation protection

Ionization of food products

International Nuclear Information System (INIS)

Vasseur, J.P.

1991-01-01

After general remarks on foods preservation, on international works and on ionization future prospects, main irradiation sources are described. Recalls on radioactivity, on radiation-matter interaction, on toxicology of ionized foods and on ionized foods detection are given. Ionization applications to various products are reviewed, especially in: - Poultry meat - Fishing products - Fresh fruits and vegetables - Dry fruits and vegetables - spices, tea, infusion - prepacked products... An evaluation of economics and sociocultural impacts is presented in connection with recent experiments [fr

Chemical data on ionizing and non-ionizing angiographic contrast materials

International Nuclear Information System (INIS)

Bonati, F.

1980-01-01

The cardiovascular effects of ionizing and non-ionizing contrast media are compared in experimental animals and in isolated heart preparations. The following parameters were recorded: peripheric arterial diastolic pressure, heart rate, duration of asystolic period, respiratory rate, contractility of the myocardium (dp/dt, LVSP, Vsub(max), EDV, ESV, SV). The observed changes are mainly due to the higher osmotic activity of the contrast media, as similar alterations were recorded after the injection of hyperosmotic glucose solution. It is concluded that administration of non-ionizing contrast media results in significantly less cardiovascular side effects. (L.E.)

Naturally occurring 32 Si and low-background silicon dark matter detectors

Energy Technology Data Exchange (ETDEWEB)

Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

2018-05-01

The naturally occurring radioisotope Si-32 represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of Si-32 and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the Si-32 concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon “ore” and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of Si-32-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in Si-32. To quantitatively evaluate the Si-32 content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon-based detectors with low levels of Si-32, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.

Naturally occurring 32Si and low-background silicon dark matter detectors

Science.gov (United States)

Orrell, John L.; Arnquist, Isaac J.; Bliss, Mary; Bunker, Raymond; Finch, Zachary S.

2018-05-01

The naturally occurring radioisotope 32Si represents a potentially limiting background in future dark matter direct-detection experiments. We investigate sources of 32Si and the vectors by which it comes to reside in silicon crystals used for fabrication of radiation detectors. We infer that the 32Si concentration in commercial single-crystal silicon is likely variable, dependent upon the specific geologic and hydrologic history of the source (or sources) of silicon "ore" and the details of the silicon-refinement process. The silicon production industry is large, highly segmented by refining step, and multifaceted in terms of final product type, from which we conclude that production of 32Si-mitigated crystals requires both targeted silicon material selection and a dedicated refinement-through-crystal-production process. We review options for source material selection, including quartz from an underground source and silicon isotopically reduced in 32Si. To quantitatively evaluate the 32Si content in silicon metal and precursor materials, we propose analytic methods employing chemical processing and radiometric measurements. Ultimately, it appears feasible to produce silicon detectors with low levels of 32Si, though significant assay method development is required to validate this claim and thereby enable a quality assurance program during an actual controlled silicon-detector production cycle.

The ionization effects from nuclear explosions in high-altitude and their effect to radio propagation

International Nuclear Information System (INIS)

Guan Rongsheng; Li Qin

1997-01-01

A high-altitude nuclear explosions releases large quantities of energetic particles and electromagnetic radiation capable of producing ionization in the atmosphere. These particles and rays radiation character in the atmosphere are discussed. Ionizations due to explosion X rays, γ rays, neutrons and β particles are considered separately. The time-space distribution of additional electron density is computed and its nature is analyzed. The effects of explosion-induced ionization on the absorption of radio wave is considered and the dependence of the absorption on explosion characteristics, distance from the earth's atmosphere, and frequency of the radio wave is determined

Electret ionization chamber: a new method for detection and dosimetry of thermal neutrons

International Nuclear Information System (INIS)

Ghilardi, A.J.P.

1988-01-01

An electret ionization chamber with boron coated walls is presented as a new method for detecting thermal neutrons. The efficiency of electret ionization chambers with different wall materials for the external electrode was inferred from the results. Detection of slow neutrons with discrimination against the detection of γ-rays and energetic neutrons was shown to depend on the selection of these materials. The charge stability over a long period of time and the charge decay owing to natural radiation were also studied. Numerical analysis was developed by the use of a micro-computer PC-XT. Both the experimental and numerical results show that the sensitivity of the electret ionization chamber for detection of thermal neutrons is comparable with that of the BF 3 ionization chamber and that new technologies for deposition of the boron layer will produce higher efficiency detectors. (author). 102 refs, 32 fig, 10 tabs

Ionizing radiations

International Nuclear Information System (INIS)

Anon.

1999-01-01

This is an update about the radiological monitoring in base nuclear installations. A departmental order of the 23. march 1999 (J.O.28. april, p.6309) determines the enabling rules by the Office of Protection against Ionizing Radiations of person having at one's disposal the results with names of individual exposure of workers put through ionizing radiations. (N.C.)

Remote detection and ecological monitoring of the industrial and natural nuclei activity of radioactive elements based on passive microwave radiometry

Science.gov (United States)

Chistyakova, Liliya K.; Chistyakov, Vyacheslav Y.; Losev, Dmitry V.; Penin, Sergei T.; Tarabrin, Yurij K.; Yakubov, Vladimir P.; Yurjev, Igor A.

1998-12-01

The passive remote method of microwave radiometry and its instrumental realization for express diagnostics of radioactive elements in the atmosphere have been discussed. Analysis of the microwave radiation due to ionization and dissociation of atmospheric components interacting with radioactive elements is carried out. The photochemical processes resulting in background microwave radiation power have been discussed. As an example, the results of natural experiment of detecting the atomic hydrogen radiation in the plume of emissions of nuclear cycle processing plants have been presented.

Investigation of dielectric constant variations for Malaysians soil species towards its natural background dose

Science.gov (United States)

Jafery, Khawarizmi Mohd; Embong, Zaidi; Khee, Yee See; Haimi Dahlan, Samsul; Tajudin, Saiful Azhar Ahmad; Ahmad, Salawati; Kudnie Sahari, Siti; Maxwell, Omeje

2018-01-01

The correlation of natural background gamma radiation and real part of the complex relative permittivity (dielectric constant) for various species Malaysian soils was investigated in this research. The sampling sites were chosen randomly according to soils groups that consist of sedentary, alluvial and miscellaneous soil which covered the area of Batu Pahat, Kluang and Johor Bahru, Johor state of Malaysia. There are 11 types of Malaysian soil species that have been studied; namely Peat, Linau-Sedu, Selangor-Kangkong, Kranji, Telemong-Akob-Local Alluvium, Holyrood-Lunas, Batu Anam-Melaka-Tavy, Harimau Tampoi, Kulai-Yong Peng, Rengam-Jerangau, and Steepland soils. In-situ exposure rates of each soil species were measured by using portable gamma survey meter and ex-situ analysis of real part of relative permittivity was performed by using DAK (Dielectric Assessment Kit assist by network analyser). Results revealed that the highest and the lowest background dose rate were 94 ± 26.28 μR hr-1 and 7 ± 0.67 μR hr-1 contributed by Rengam Jerangau and Peat soil species respectively. Meanwhile, dielectric constant measurement, it was performed in the range of frequency between 100 MHz to 3 GHz. The measurements of each soils species dielectric constant are in the range of 1 to 3. At the lower frequencies in the range of 100 MHz to 600 MHz, it was observed that the dielectric constant for each soil species fluctuated and inconsistent. But it remained consistent in plateau form of signal at higher frequency at range above 600 MHz. From the comparison of dielectric properties of each soil at above 600 MHz of frequency, it was found that Rengam-Jerangau soil species give the highest reading and followed by Selangor-Kangkong species. The average dielectric measurement for both Selangor-Kangkong and Rengam-Jerangau soil species are 2.34 and 2.35 respectively. Meanwhile, peat soil species exhibits the lowest dielectric measurement of 1.83. It can be clearly seen that the pattern

Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z~6 Quasars. II. A Sample of 19 Quasars

Science.gov (United States)

Fan, Xiaohui; Strauss, Michael A.; Becker, Robert H.; White, Richard L.; Gunn, James E.; Knapp, Gillian R.; Richards, Gordon T.; Schneider, Donald P.; Brinkmann, J.; Fukugita, Masataka

2006-07-01

We study the evolution of the ionization state of the intergalactic medium (IGM) at the end of the reionization epoch using moderate-resolution spectra of a sample of 19 quasars at 5.745.7: the GP optical depth evolution changes from τeffGP~(1+z)4.3 to (1+z)>~11, and the average length of dark gaps with τ>3.5 increases from 80 comoving Mpc. The dispersion of IGM properties along different lines of sight also increases rapidly, implying fluctuations by a factor of >~4 in the UV background at z>6, when the mean free path of UV photons is comparable to the correlation length of the star-forming galaxies that are thought to have caused reionization. The mean length of dark gaps shows the most dramatic increase at z~6, as well as the largest line-of-sight variations. We suggest using dark gap statistics as a powerful probe of the ionization state of the IGM at yet higher redshift. The sizes of H II regions around luminous quasars decrease rapidly toward higher redshift, suggesting that the neutral fraction of the IGM has increased by a factor of >~10 from z=5.7 to 6.4, consistent with the value derived from the GP optical depth. The mass-averaged neutral fraction is 1%-4% at z~6.2 based on the GP optical depth and H II region size measurements. The observations suggest that z~6 is the end of the overlapping stage of reionization and are inconsistent with a mostly neutral IGM at z~6, as indicated by the finite length of the dark absorption gaps. Based on observations obtained with the Sloan Digital Sky Survey at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, made possible by the generous financial support of the W. M. Keck Foundation, with the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution, and with the Kitt Peak National Observatory 4 m Mayall Telescope. This paper

Characteristics of natural background external radiation and effective dose equivalent

International Nuclear Information System (INIS)

Fujimoto, Kenzo

1989-01-01

The two sources of natural radiation - cosmic rays and primordial radionuclides - are described. The factors affecting radiation doses received from natural radiation and the calculation of effective dose equivalent due to natural radiation are discussed. 10 figs., 3 tabs

On the mechanism of the biological effect of ionizing radiation

International Nuclear Information System (INIS)

Margulis, M.A.; Margulis, I.M.

2005-01-01

The mechanisms of the biological effects of ionizing radiation (IR) and ultrasound (US) were considered. The current views on the nature of toxicity of IR, which is usually assigned to the formation of radicals in living tissues and to the straight-line collision of an ionizing particle with the DNA molecule, were analyzed. It was established that the amount of radicals formed in biological tissues in conditions of ultrasonically induced cavitation can be as large as that for IR; however, the biological effect of US is much softer as compared to IR. It was shown that the contribution of the indirect mechanism to the total biological effect of IR can be estimated by comparing US and IR in their chemical action; the contribution of the indirect mechanism to the biological effect of IR was found to be negligibly small. An alternative mechanism was proposed to explain the biological effect of IR. In accordance with the proposed model, IR with a high linear energy transfer (LET) value breaks through cell walls and biological membranes and causes damage to them, such that the cell can lose its regenerative capacity. Moreover, high-energy heavy ionizing particles perforate cytoplasm to form channels. Ionizing radiation with a low LET value (γ- and X-rays) causes multiple damages to biological membranes. Ionizing particles can also cause damages to membranes of mitochondria thus affecting the mechanism of cellular respiration, which will cause neoplastic diseases. The straight-line collision of an ionizing particle with a DNA molecule was found to be 5-7 orders of magnitude less probable as compared to the collision with a wall or membrane. It was shown that multiple perforations of cell walls and damages to membranes are characteristic only of ionizing particles, which have sufficiently long tracks, and do not occur upon exposure to ultrasonic waves, microwaves, UV radiation, and magnetic fields [ru

Background noise in amplifiers of pulse ionization rooms; Le bruit de fond dans les amplificateurs de chambre d'ionisation a impulsions

Energy Technology Data Exchange (ETDEWEB)

Valladas, G; Leveque, A [Commissariat a l' Energie Atomique, Lab. du Fort de Chatillon, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1952-07-01

The accuracy on the charge measures liberated in a pulse ionization room is limited by the background noise inherent to the used amplifier. Firstly we remind briefly the main features of the signal collected on the electrode collector of the room and the background noise, then the theory of Milatz and Keller. This theory establishes the existence of an absolute limit on the precision of the measures, characteristic of the preamplifier tube and permits its calculation. We define the transient answer of an ideal amplifier allowing effectively this precision. We propose a convenient circuit having this answer and we compare with the usually used circuits. In the case the method of Scherr and Peterson, we show that a supplementary condition render the previous theory insufficient. We calculate the optimum transient response in this case and the value of the limit of precision who ensues. We consider some simple circuits and compare to this limit the precision that they permit to get. (author) [French] La precision sur les mesures de charges liberees dans une chambre d'ionisation a impulsions est limitee par le bruit de fond inherent a l'amplificateur utilise. Nous rappelons brievement tout d'abord les caracteristiques principales du signal recueilli sur l'electrode collectrice de la chambre et du bruit de fond, puis la theorie de Milatz et Keller. Cette theorie etablit l'existence d'une limite absolue sur la precision des mesures, caracteristique du tube preamplificateur, et permet son calcul. Nous definissons la reponse transitoire de l'amplificateur ideal permettant d'attendre effectivement cette precision. Nous proposons un circuit pratique ayant cette reponse et nous lui comparons les circuits habituellement utilises. Dans le cas ou l'on emploie la methode de Scherr et Peterson, nous montrons qu'une condition supplementaire s'introduit rendant la theorie precedente insuffisante. Nous calculons donc la reponse transitoire optimum dans ce cas et la valeur de la

Detecting signatures of cosmological recombination and reionization in the cosmic radio background

Science.gov (United States)

Subrahmanyan, Ravi; Shankar Narayana Rao, Udaya; Sathyanarayana Rao, Mayuri; Singh, Saurabh

2015-08-01

Evolution of the baryons during the Epochs of cosmological Recombination and Reionization has left traces in the cosmic radio background in the form of spectral distortions (Sunyaev & Chluba 2008 Astron. Nachrichten, 330, 657; Pritchard & Loeb 2012 Rep Prog Phys 75(8):086901). The spectral signature depends on the evolution in the ionization state in hydrogen and helium and on the spin temperature of hydrogen. These probe the physics of energy release beyond the last scattering surface at redshifts exceeding 1090 and the nature of the first sources and gas evolution down to redshift about 6. The spectral distortions are sensitive to the nature of the first stars, ultra-dwarf galaxies, accreting compact objects, and the evolving ambient radiation field: X-rays and UV from the first sources. Detection of the all-sky or global spectral distortions in the radio background is hence a probe of cosmological recombination and reionization.We present new spectral radiometers that we have purpose designed for precision measurements of spectral distortions at radio wavelengths. New antenna elements include frequency independent and electrically small fat-dipole (Raghunathan et al. 2013 IEEE TAP, 61, 3411) and monopole designs. Receiver configurations have been devised that are self-calibratable (Patra et al. 2013 Expt Astron, 36, 319) so that switching of signal paths and of calibration noise sources provide real time calibration for systematics and receiver noise. Observing strategies (Patra et al. arXiv:1412.7762) and analysis methods (Satyanarayana Rao et al. arXiv:1501.07191) have been evolved that are capable of discriminating between the cosmological signals and the substantially brighter foregrounds. We have also demonstrated the value of system designs that exploit advantages of interferometer detection (Mahesh et al. arXiv:1406.2585) of global spectral distortions.Finally we discuss how the Square Kilometer Array stations may be outfitted with precision spectral

Interactive visual intervention planning in particle accelerator environments with ionizing radiation

International Nuclear Information System (INIS)

Fabry, Thomas

2014-01-01

Radiation is omnipresent. It has many interesting applications: in medicine, where it allows curing and diagnosing patients; in communication, where modern communication systems make use of electromagnetic radiation; and in science, where it is used to discover the structure of materials; to name a few. Physically, radiation is a process in which particles or waves travel through any kind of material, usually air. Radiation can be very energetic, in which case it can break the atoms of ordinary matter (ionization). If this is the case, radiation is called ionizing. It is known that ionizing radiation can be far more harmful to living beings than non-ionizing radiation. In this dissertation, we are concerned with ionizing radiation. Naturally occurring ionizing radiation in the form of radioactivity is a most natural phenomenon. Almost everything is radioactive: there is radiation emerging from the soil, it is in the air, and the whole planet is constantly undergoing streams of energetic cosmic radiation. Since the beginning of the twentieth century, we are also able to artificially create radioactive matter. This has opened a lot of interesting technological opportunities, but has also given a tremendous responsibility to humanity, as the nuclear accidents in Chernobyl and Fukushima, and various accidents in the medical world have made clear. This has led to the elaboration of a radiological protection system. In practice, the radiological protection system is mostly implemented using a methodology that is indicated with the acronym ALARA: As Low As Reasonably Achievable. This methodology consists of justifying, optimizing and limiting the radiation dose received. This methodology is applied in conjunction with the legal limits. The word 'reasonably' means that the optimization of radiation exposure has to be seen in context. The optimization is constrained by the fact that the positive effects of an operation might surpass the negative effects caused by the

Ionizing radiation - one of the most important link of the energetic chain in biological cell

Energy Technology Data Exchange (ETDEWEB)

Goraczko, W. [Technical Univ. Poznan, Radio- and Photochemistry Dept., Poznan (Poland)

1999-09-01

High (large) and low (small) doses of ionizing radiation consistently induce opposite physiologic effects in biological systems. The effects of low doses cannot be inferred by interpolation between the result from groups exposed to high doses and controls irradiated only by Natural Background Radiation. Stimulation ('bio-positive') effects by low-level doses of ionizing radiation are called radiation hormesis. It is still controversial idea, however it was found that some biological objects (yeast, seeds, animals) after gamma irradiation by low-level doses (10-50 times more NBR) can increase their development. The result of present researches demonstrate that the excitation of living system by gamma quanta (high energy) initiates prolonged secondary emission that influences biota and activates many important processes in biological systems. According to the excitation theory of bio-molecules the author suggests that gamma irradiation in low-level doses excites such molecules as DNA and proteins, and this being followed by a long-termed secondary coherent radiation. The spectral analysis of this secondary emission confirmed the contribution of the UV component to the total emission. The data obtaining by using SPC method (single photon counting) make possible a partial understanding of the radiation hormesis phenomenon and suggest closer relationship to UV emission from biological systems during mitotic processes. The experiments with humic acid (high doses) and glycine (low doses) confirm the author hypothesis that gamma-irradiated organic compounds are capable to emit secondary radiation. This secondary radiation probably plays very significant role in the intercellular communication inside the living systems. In conclusion the author proposed de-excitation processes in bio-molecules as a common denominator of UV and ionizing radiation interacting with living cells. Finally he refers to the Cerenkov radiation which is created inside the biological cells

Ionizing radiation - one of the most important link of the energetic chain in biological cell

International Nuclear Information System (INIS)

Goraczko, W.

1999-01-01

High (large) and low (small) doses of ionizing radiation consistently induce opposite physiologic effects in biological systems. The effects of low doses cannot be inferred by interpolation between the result from groups exposed to high doses and controls irradiated only by Natural Background Radiation. Stimulation ('bio-positive') effects by low-level doses of ionizing radiation are called radiation hormesis. It is still controversial idea, however it was found that some biological objects (yeast, seeds, animals) after gamma irradiation by low-level doses (10-50 times more NBR) can increase their development. The result of present researches demonstrate that the excitation of living system by gamma quanta (high energy) initiates prolonged secondary emission that influences biota and activates many important processes in biological systems. According to the excitation theory of bio-molecules the author suggests that gamma irradiation in low-level doses excites such molecules as DNA and proteins, and this being followed by a long-termed secondary coherent radiation. The spectral analysis of this secondary emission confirmed the contribution of the UV component to the total emission. The data obtaining by using SPC method (single photon counting) make possible a partial understanding of the radiation hormesis phenomenon and suggest closer relationship to UV emission from biological systems during mitotic processes. The experiments with humic acid (high doses) and glycine (low doses) confirm the author hypothesis that gamma-irradiated organic compounds are capable to emit secondary radiation. This secondary radiation probably plays very significant role in the intercellular communication inside the living systems. In conclusion the author proposed de-excitation processes in bio-molecules as a common denominator of UV and ionizing radiation interacting with living cells. Finally he refers to the Cerenkov radiation which is created inside the biological cells. Because

The Limiting background in a dark matter search at shallow depth

Energy Technology Data Exchange (ETDEWEB)

Perera, Thushara A. [Case Western Reserve U.

2002-01-01

A convincing body of evidence from observational and theoretical astrophysics suggests that matter in the universe is dominated by a non-luminous, non-baryonic, non-relativistic component. Weakly Interacting Massive Particles (WIMPs) are a proposed particle candidate that satisfy all of the above criteria. They are a front-runner among dark matter candidates because their predicted contribution to matter in the universe is cosmologically signicant and because they may arise naturally from supersymmetric (SUSY) models of particle physics. The Cryogenic Dark Matter Search (CDMS) employs advanced detectors sensitive to nuclear recoils caused by WIMP scatters and capable of rejecting ionizing backgrounds. The rst phase of the experiment, conducted at a shallow site, is limited by a background of neutrons which are indistinguishable from WIMPs in terms of the acquired data. By accounting for and statistically subtracting these neutrons, CDMS I provides the best dark matter limits to date over a wide range of WIMP masses above 10 GeV/c2 . These results also exclude the signal region claimed by the DAMA annual modulation search at a >71% condence level. The second phase of the experiment, located at a deep site, is scheduled to begin data acquisition in 2002. Due to longer exposures, larger detector mass, and low background rates at this site, data from CDMS II are expected to improve on present WIMP sensitivity by about two orders of magnitude. Emphasized in this work are the research topics in which I have been directly involved. These include the work described in Chapters 3 and 5 with regard to the development and use of simulation tools, detailed studies into the limiting neutron background, and the present understanding of this background in relation to CDMS I and CDMS II. I was also involved in several detector development projects in preparation for CDMS II. Analysis of test data from a ZIP detector, planned for use in CDMS II, is presented in Chapter 6.

The nature of luminous Ly α emitters at z ˜ 2-3: maximal dust-poor starbursts and highly ionizing AGN

Science.gov (United States)

Sobral, David; Matthee, Jorryt; Darvish, Behnam; Smail, Ian; Best, Philip N.; Alegre, Lara; Röttgering, Huub; Mobasher, Bahram; Paulino-Afonso, Ana; Stroe, Andra; Oteo, Iván

2018-06-01

Deep narrow-band surveys have revealed a large population of faint Ly α emitters (LAEs) in the distant Universe, but relatively little is known about the most luminous sources ({L}_{Lyα } ≳ 10^{42.7} erg s-1; L_{Lyα }≳ L^*_{Lyα }). Here we present the spectroscopic follow-up of 21 luminous LAEs at z ˜ 2-3 found with panoramic narrow-band surveys over five independent extragalactic fields (≈4 × 106 Mpc3 surveyed at z ˜ 2.2 and z ˜ 3.1). We use WHT/ISIS, Keck/DEIMOS, and VLT/X-SHOOTER to study these sources using high ionization UV lines. Luminous LAEs at z ˜ 2-3 have blue UV slopes (β =-2.0^{+0.3}_{-0.1}) and high Ly α escape fractions (50^{+20}_{-15} per cent) and span five orders of magnitude in UV luminosity (MUV ≈ -19 to -24). Many (70 per cent) show at least one high ionization rest-frame UV line such as C IV, N V, C III], He II or O III], typically blue-shifted by ≈100-200 km s-1 relative to Ly α. Their Ly α profiles reveal a wide variety of shapes, including significant blue-shifted components and widths from 200 to 4000 km s-1. Overall, 60 ± 11 per cent appear to be active galactic nucleus (AGN) dominated, and at LLyα > 1043.3 erg s-1 and/or MUV sharp transition in the nature of LAEs, from star formation dominated to AGN dominated.

Initial events in the cellular effects of ionizing radiations: clustered damage in DNA

International Nuclear Information System (INIS)

Goodhead, D.T.

1994-01-01

Ionizing radiations produce many hundreds of different simple chemical products in DNA and also multitudes of possible clustered combinations. The simple products, including single-strand breaks, tend to correlate poorly with biological effectiveness. Even for initial double-strand breaks, as a broad class, there is apparently little or no increase in yield with increasing ionization density, in contrast with the large rise in relative biological effectiveness for cellular effects. Track structure analysis has revealed that clustered DNA damage of severity greater than simple double-strand breaks is likely to occur at biologically relevant frequencies with all ionizing radiations. Studies are in progress to describe in more detail the chemical nature of these clustered lesions and to consider the implications for cellular repair. (author)

Simulation study of the ionizing front in the critical ionization velocity phenomenon

International Nuclear Information System (INIS)

Machida, S.; Goertz, C.K.; Lu, G.

1988-01-01

Simulations of the Critical Ionization Velocity (CIV) for a neutral gas cloud moving across the static magnetic field are made. We treat a low-β plasma and use a 2-1/2 D electrostatic code linked with our Plasma and Neutral Interaction Code (PANIC). Our study is focused on the understanding of the interface between the neutral gas cloud and the surrounding plasma where the strong interaction takes place. We assume the existence of some hot electrons in the ambient plasma to provide a seed ionization for CIV. When the ionization starts a sheath-like structure is formed at the surface of the neutral gas (Ionizing Front). In that region the crossfield component of the electric field causes the electron to E x B drift with a velocity of the order of the neutral gas velocity times the square root of the ion to electron mass ratio. Thus the kinetic energy of the drifting electrons can be large enough for electron impact ionization. In addition a diamagnetic drift of the electron occurs due to the number density and temperature inhomogeneity in the ionization front. These drift currents excite the lower-hybrid waves with the wave k-vectors almost perpendicular to the neutral flow and magnetic field again resulting in electron heating and additional ionization. The overall structure is studied by developing a simple analytic model as well as making simulation runs. (author)

Introduction to ionizing radiation physics

International Nuclear Information System (INIS)

Musilek, L.

1979-01-01

Basic properties are described of the atom, atomic nucleus and of ionizing radiation particles; nuclear reactions, ionizing radiation sources and ionizing radiation interaction with matter are explained. (J.P.)

Collisional ionization

International Nuclear Information System (INIS)

Arnaud, M.

1985-07-01

In low density, thin plasmas (such as stellar coronae, interstellar medium, intracluster medium) the ionization process is governed by collision between electrons and ions in their ground state. In view of the recent improvements we thought an updating of ionization rates was really needed. The work is based on both experimental data and theoretical works and give separate estimates for the direct and autoionization rates

Low level ionizing radiation and human mortality: multi-regional epidemiological studies

International Nuclear Information System (INIS)

Hickey, R.J.; Bowers, E.J.; Spence, D.E.; Zemel, B.S.; Clelland, A.B.; Clelland, R.C.

1981-01-01

Analyses of relationships involving environmental chemicals, background radiation, and mortality rates for diseases of the heart and several cancer categories are presented. Bivariate correlation coefficients between radiation and mortality rate were significantly negative for cancer of the lung and respiratory organs, cancer of the buccal cavity and pharynx, cancer of the digestive organs and peritoneum, total cancer and diseases of the heart. Only the correlation coefficient between background radiation and leukemia-aleukemia was positive, and that not significantly positive. Initial multivariate statistical studies support the bivariate results in that all significant regression terms that represent background radiation have been negative. Background radiation level was not a significant predictor for leukemia-aleukemia mortality rate when examined without regard to age. This preliminary work suggests that any health effects of background radiation on the diseases studied do not exceed in magnitude those of environmental chemicals. It also suggests that models implying important long-term deleterious effects of low levels of ionizing radiation on humans may be invalid. (author)

Spectra of highly ionized atoms of tokamak interest

International Nuclear Information System (INIS)

Cowan, R.D.

1977-01-01

The general nature of the change in energy level structures along an isoelectronic sequence is reviewed, with particular emphasis on relativistic effects and changes in coupling conditions. The accuracy of computed wavelengths is checked by comparison with experimental data on inner-shell (x-ray) transitions in singly ionized atoms. Relativistic effects can be extremely important for Δn = 0 transitions, but are taken into account fairly accurately by the approximate relativistic methods used. Computed ionization energies are given for important ions of Cr, Fe, Ni, Kr, Mo, Xe, W, and Au. Computed wavelengths and oscillator strengths are given for resonance lines of most of these elements in the simple isoelectronic sequences of neutral Li, Be, Na, Mg, K, Ni, Cu, and Zn, and more detailed electric- and magnetic-dipole spectra are given for ions of greatest importance

Radiation hydrodynamical instabilities in cosmological and galactic ionization fronts

Science.gov (United States)

Whalen, Daniel J.; Norman, Michael L.

2011-11-01

Ionization fronts, the sharp radiation fronts behind which H/He ionizing photons from massive stars and galaxies propagate through space, were ubiquitous in the universe from its earliest times. The cosmic dark ages ended with the formation of the first primeval stars and galaxies a few hundred Myr after the Big Bang. Numerical simulations suggest that stars in this era were very massive, 25-500 solar masses, with H(II) regions of up to 30,000 light-years in diameter. We present three-dimensional radiation hydrodynamical calculations that reveal that the I-fronts of the first stars and galaxies were prone to violent instabilities, enhancing the escape of UV photons into the early intergalactic medium (IGM) and forming clumpy media in which supernovae later exploded. The enrichment of such clumps with metals by the first supernovae may have led to the prompt formation of a second generation of low-mass stars, profoundly transforming the nature of the first protogalaxies. Cosmological radiation hydrodynamics is unique because ionizing photons coupled strongly to both gas flows and primordial chemistry at early epochs, introducing a hierarchy of disparate characteristic timescales whose relative magnitudes can vary greatly throughout a given calculation. We describe the adaptive multistep integration scheme we have developed for the self-consistent transport of both cosmological and galactic ionization fronts.

Dosimetry of ionizing radiation

International Nuclear Information System (INIS)

Musilek, L.; Seda, J.; Trousil, J.

1992-01-01

The publication deals with a major field of ionizing radiation dosimetry, viz., integrating dosimetric methods, which are the basic means of operative dose determination. It is divided into the following sections: physical and chemical effects of ionizing radiation; integrating dosimetric methods for low radiation doses (film dosimetry, nuclear emulsions, thermoluminescence, radiophotoluminescence, solid-state track detectors, integrating ionization dosemeters); dosimetry of high ionizing radiation doses (chemical dosimetric methods, dosemeters based on the coloring effect, activation detectors); additional methods applicable to integrating dosimetry (exoelectron emission, electron spin resonance, lyoluminescence, etc.); and calibration techniques for dosimetric instrumentation. (Z.S.). 422 refs

Teachers' Knowledge and Views on the Use of Learners' Socio-Cultural Background in Teaching Natural Sciences in Grade 9 Township Classes

Science.gov (United States)

Mavuru, Lydia; Ramnarain, Umesh

2017-01-01

This article explores teachers' knowledge and views on the role of learners' socio-cultural background when teaching Natural Sciences to Grade 9 learners at three South African township schools. Within a socio-cultural framework, the research investigated how teachers accommodate learners' cultural norms and values, religion and beliefs,…

First successful ionization of Lr (Z = 103) by a surface-ionization technique

Energy Technology Data Exchange (ETDEWEB)

Sato, Tetsuya K., E-mail: sato.tetsuya@jaea.go.jp; Sato, Nozomi; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Ooe, Kazuhiro; Miyashita, Sunao; Schädel, Matthias [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Kaneya, Yusuke; Nagame, Yuichiro [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Graduate School of Science and Engineering, Ibaraki University, 2-1-1, Bunkyo, Mito, Ibaraki 310-8512 (Japan); Osa, Akihiko [Department of Research Reactor and Tandem Accelerator, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Ichikawa, Shin-ichi [Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Stora, Thierry [ISOLDE, CERN, CH-1211 Geneva 23 (Switzerland); Kratz, Jens Volker [Institut für Kernchemie, Universität Mainz, D-55099 Mainz (Germany)

2013-02-15

We have developed a surface ionization ion-source as part of the JAEA-ISOL (Isotope Separator On-Line) setup, which is coupled to a He/CdI{sub 2} gas-jet transport system to determine the first ionization potential of the heaviest actinide lawrencium (Lr, Z = 103). The new ion-source is an improved version of the previous source that provided good ionization efficiencies for lanthanides. An additional filament was newly installed to give better control over its operation. We report, here, on the development of the new gas-jet coupled surface ion-source and on the first successful ionization and mass separation of 27-s {sup 256}Lr produced in the {sup 249}Cf + {sup 11}B reaction.

Optimal Background Attenuation for Fielded Radiation Detection Systems

International Nuclear Information System (INIS)

Robinson, Sean M.; Kaye, William R.; Schweppe, John E.; Siciliano, Edward R.

2006-01-01

Radiation detectors are often placed in positions difficult to shield from the effects of terrestrial background. This is particularly true in the case of Radiation Portal Monitor (RPM) systems, as their wide viewing angle and outdoor installations make them susceptible to terrestrial background from the surrounding area. A low background is desired in most cases, especially when the background noise is of comparable strength to the signal of interest. The problem of shielding a generalized RPM from terrestrial background is considered. Various detector and shielding scenarios are modeled with the Monte-Carlo N Particle (MCNP) computer code. Amounts of nominal-density shielding needed to attenuate the terrestrial background to varying degrees are given, along with optimal shielding geometry to be used in areas where natural shielding is limited, and where radiation detection must occur in the presence of natural background. Common shielding solutions such as steel plating are evaluated based on the signal to noise ratio and the benefits are weighed against the incremental cost.

A background free double beta decay experiment

International Nuclear Information System (INIS)

Giomataris, I

2011-01-01

We present a new detection scheme for rejecting backgrounds in neutrino-less double beta decay experiments. It relies on the detection of Cherenkov light emitted by electrons in the MeV region. The momentum threshold is tuned to reach a good discrimination between background and good events. We consider many detector concepts and a range of target materials. The most promising is the high-pressure 136 Xe emitter where the required energy threshold is easily adjusted. Combination of this concept and a high pressure Time Projection Chamber could provide an optimal solution. A simple and low cost effective solution is the use of the Spherical Proportional Counter that provides, using a single read-out channel, two delayed signals from ionization and Cherenkov light. In solid-state double beta decay emitters, because of its higher density, the considered process is out of energy range. An escape will be the fabrication of double decay emitters having lower density by using for instance the aerogel technique. It is surprising that a technology used for particle identification in high-energy physics becomes a powerful tool for rejecting backgrounds in such low-energy experiments.

Resonance enhanced multiphoton ionization spectra of molecules and molecular fragments. Annual progress report, March 1992 - February 1993

International Nuclear Information System (INIS)

1993-01-01

In this report, the author will review the progress made in his studies of ion rotational distributions resulting from resonance enhanced multiphoton ionization of excited electronic states and from single-photon ionization of ground electronic states of jet-cooled molecules by coherent VUV and XUV radiation. To do so he will select a few examples from his studies which serve to highlight his progress and to identify the background and significance of the specific spectral features and systems he has chosen to study

Alpha radioactivity measurement technology with ionized air type measurement. Applicability evaluation to verification of the clearance level

International Nuclear Information System (INIS)

Mita, Yutaka; Matsumura, Toshihiro; Yokoyama, Kaoru; Sugitsue, Noritake

2008-10-01

The purpose of this test is to evaluate the applicability of the clearance level measuring system by Ionized Air Type Measurement after decontaminated by sulfuric acid sample. In Ningyo-toge Environmental Engineering Center. The equipment and radioactive waste which were contaminated with uranium are generated so much in future dismantling stage. In our plan, some of equipments and radioactive waste are contaminated to a clearance level, and cut down on decommission and disposal expense. This plan needs the alpha-rays measurement technology of the very low level. We think that ionized Air transfer measurement technology is promising as of clearance verification technology. The ionized Air transfer measurement technology applied to the Ionized Air Type Measurement can measure plan radioactivity of a very low level. Moreover, as compared with a direct survey, there is the merit which can be measured in a short time. However ionized Air transfer measurement technology is new technology. Therefore, there is almost no measurement track record. Furthermore, the date about the influence of a background, a detection limit, measurement performance, and reliability is insufficient. So, this measurement test estimated applicability as clearance level verification of an Ionized Air Type Measurement. (author)

Ionization chamber

International Nuclear Information System (INIS)

Jilbert, P.H.

1975-01-01

The invention concerns ionization chambers with particular reference to air-equivalent ionization chambers. In order to ensure that similar chambers have similar sensitivities and responses the surface of the chamber bounding the active volume carries a conducting material, which may be a colloidal graphite, arranged in the form of lines so that the area of the conducting material occupies only a small proportion of the area of said surface. (U.S.)

Ionizing radiation interactions with DNA: nanodosimetry; Ionisierende Strahlungswechselwirkung mit der DNS. Nanodosimetrie

Energy Technology Data Exchange (ETDEWEB)

Bug, Marion; Nettelbeck, Heidi [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Arbeitsgruppe ' Biologische Wirksamkeit ionisierender Strahlung' ; Hilgers, Gerhard [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Arbeitsgruppe ' Nanodosimetrie' ; Rabus, Hans [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany). Fachbereich ' Grundlagen der Dosimetrie'

2011-06-15

The metrology of ionizing radiation is based on measuring values that are averaged over macroscopic volume elements, for instance the energy dose is defined as ratio of the energy deposited on the absorber and the absorber mass. For biological or medical radiation effects the stochastic nature of radiation interaction is of main importance, esp. the interaction of ionizing radiation with the DNA as the genetic information carrier. For radiotherapy and risk evaluation purposes a comprehensive system of radiation weighing factors and other characteristics, like radiation quality or relative biological efficacy was developed. The nanodosimetry is aimed to develop a metrological basis relying on physical characteristics of the microscopic structure of ionizing radiation tracks. The article includes the development of experimental nanodosimetric methods, the respective calibration techniques, Monte-Carlo simulation of the particle track microstructure and the correlation nanodosimetry and biological efficiency.

Multiphoton ionization of the hydrogen atom by a circularly polarized electromagnetic field

International Nuclear Information System (INIS)

Prepelitsa, O.B.

1999-01-01

This paper examines the multiphoton ionization of the ground state of the hydrogen atom in the field of a circularly polarized intense electromagnetic wave. To describe the states of photoelectrons, quasiclassical wave functions are introduced that partially allow for the effect of an intense electromagnetic wave and that of the Coulomb potential. Expressions are derived for the angular and energy distributions of photoelectrons with energies much lower than the ionization potential of an unperturbed atom. It is found that, due to allowance for the Coulomb potential in the wave function of the final electron states, the transition probability near the ionization threshold tends to a finite value. In addition, the well-known selection rules for multiphoton transitions in a circularly polarized electromagnetic field are derived in a natural way. Finally, the results are compared with those obtained in the Keldysh-Faisal-Reiss approximation

Effects of the ionizing radiation in natural food colours; Efeitos da radiacao ionizante em corantes naturais de uso alimenticio

Energy Technology Data Exchange (ETDEWEB)

Cosentino, Helio Morrone

2005-07-01

The world's fast growing population and its consequent increase in demand for food has driven mankind into improving technologies which ensure a safer supply of such commodities. Both food radiation processing and its constituents are highlighted as a feasible alternative technique capable of meeting food safety standards. Natural dyes are extensively employed in the food industry thanks to their colour enhancing properties on food products. This paper has aimed at studying the effects of ionizing radiation on three natural dyes: carminic acid and its derivatives (cochineal dyes), bixine and its salts (annatto dyes) and curcumin (turmeric dyes), used in the food and cosmetic industries within dilutions and doses those goods might eventually be processed in. It also envisages clarifying the compatibility of the irradiation technique with the keeping of such relevant sensorial attribute which is the product colour. Spectrophotometry and capillary electrophoresis were the analytic methods employed. All in all, a colour decrease proportional to the increase on the applied gamma radiation (1 to 32 kGy) has been observed. The annatto dyes have proven moderately stable whereas turmeric has shown to be highly sensitive to radiation. Those results shall be taken into account as far as the need to alter the formulae additive amount in the product is concerned whenever undergoing radiation processing. (author)

Plasma production via field ionization

Directory of Open Access Journals (Sweden)

C. L. O’Connell

2006-10-01

Full Text Available Plasma production via field ionization occurs when an incoming particle beam is sufficiently dense that the electric field associated with the beam ionizes a neutral vapor or gas. Experiments conducted at the Stanford Linear Accelerator Center explore the threshold conditions necessary to induce field ionization by an electron beam in a neutral lithium vapor. By independently varying the transverse beam size, number of electrons per bunch, or bunch length, the radial component of the electric field is controlled to be above or below the threshold for field ionization. Additional experiments ionized neutral xenon and neutral nitric oxide by varying the incoming beam’s bunch length. A self-ionized plasma is an essential step for the viability of plasma-based accelerators for future high-energy experiments.

Ionization mechanisms in capillary supercritical fluid chromatography-chemical ionization mass spectrometry

NARCIS (Netherlands)

Houben, R.J.; Leclercq, P.A.; Cramers, C.A.M.G.

1991-01-01

Ionization mechanisms have been studied for supercritical fluid chromatography (SFC) with mass spectrometric (MS) detection. One of the problems associated with SFC-MS is the interference of mobile phase constituents in the ionization process, which complicates the interpretation of the resulting

The Formation and Physical Origin of Highly Ionized Cooling Gas

Energy Technology Data Exchange (ETDEWEB)

Bordoloi, Rongmon [MIT-Kavli Center for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA, 02139 (United States); Wagner, Alexander Y. [University of Tsukuba, Center for Computational Sciences, Tennodai 1-1-1, Tsukuba, Ibaraki (Japan); Heckman, Timothy M.; Norman, Colin A., E-mail: bordoloi@mit.edu, E-mail: bordoloi@mit.edu [Department of Physics and Astronomy, John Hopkins University, 21218, Baltimore, MD (United States)

2017-10-20

We present a simple model that explains the origin of warm, diffuse gas seen primarily as highly ionized absorption-line systems in the spectra of background sources. We predict the observed column densities of several highly ionized transitions such as O vi, O vii, Ne viii, N v, and Mg x, and we present a unified comparison of the model predictions with absorption lines seen in the Milky Way disk, Milky Way halo, starburst galaxies, the circumgalactic medium, and the intergalactic medium at low and high redshifts. We show that diffuse gas seen in such diverse environments can be simultaneously explained by a simple model of radiatively cooling gas. We show that most such absorption-line systems are consistent with being collisionally ionized, and we estimate the maximum-likelihood temperature of the gas in each observation. This model satisfactorily explains why O vi is regularly observed around star-forming low- z L* galaxies, and why N v is rarely seen around the same galaxies. We further present some consequences of this model in quantifying the dynamics of the cooling gas around galaxies and predict the shock velocities associated with such flows. A unique strength of this model is that while it has only one free (but physically well-constrained) parameter, it nevertheless successfully reproduces the available data on O vi absorbers in the interstellar, circumgalactic, intragroup, and intergalactic media, as well as the available data on other absorption lines from highly ionized species.

Analytical modeling of Schottky tunneling source impact ionization MOSFET with reduced breakdown voltage

Directory of Open Access Journals (Sweden)

Sangeeta Singh

2016-03-01

Full Text Available In this paper, we have investigated a novel Schottky tunneling source impact ionization MOSFET (STS-IMOS to lower the breakdown voltage of conventional impact ionization MOS (IMOS and developed an analytical model for the same. In STS-IMOS there is an accumulative effect of both impact ionization and source induced barrier tunneling. The silicide source offers very low parasitic resistance, the outcome of which is an increment in voltage drop across the intrinsic region for the same applied bias. This reduces operating voltage and hence, it exhibits a significant reduction in both breakdown and threshold voltage. STS-IMOS shows high immunity against hot electron damage. As a result of this the device reliability increases magnificently. The analytical model for impact ionization current (Iii is developed based on the integration of ionization integral (M. Similarly, to get Schottky tunneling current (ITun expression, Wentzel–Kramers–Brillouin (WKB approximation is employed. Analytical models for threshold voltage and subthreshold slope is optimized against Schottky barrier height (ϕB variation. The expression for the drain current is computed as a function of gate-to-drain bias via integral expression. It is validated by comparing it with the technology computer-aided design (TCAD simulation results as well. In essence, this analytical framework provides the physical background for better understanding of STS-IMOS and its performance estimation.

Geostatistics as a tool to improve the natural background level definition: An application in groundwater.

Science.gov (United States)

Dalla Libera, Nico; Fabbri, Paolo; Mason, Leonardo; Piccinini, Leonardo; Pola, Marco

2017-11-15

The Natural Background Level (NBL), suggested by UE BRIDGE project, is suited for spatially distributed datasets providing a regional value that could be higher than the Threshold Value (TV) set by every country. In hydro-geochemically dis-homogeneous areas, the use of a unique regional NBL, higher than TV, could arise problems to distinguish between natural occurrences and anthropogenic contaminant sources. Hence, the goal of this study is to improve the NBL definition employing a geostatistical approach, which reconstructs the contaminant spatial structure accounting geochemical and hydrogeological relationships. This integrated mapping is fundamental to evaluate the contaminant's distribution impact on the NBL, giving indications to improve it. We decided to test this method on the Drainage Basin of Venice Lagoon (DBVL, NE Italy), where the existing NBL is seven times higher than the TV. This area is notoriously affected by naturally occurring arsenic contamination. An available geochemical dataset collected by 50 piezometers was used to reconstruct the spatial distribution of arsenic in the densely populated area of the DBVL. A cokriging approach was applied exploiting the geochemical relationships among As, Fe and NH4+. The obtained spatial predictions of arsenic concentrations were divided into three different zones: i) areas with an As concentration lower than the TV, ii) areas with an As concentration between the TV and the median of the values higher than the TV, and iii) areas with an As concentration higher than the median. Following the BRIDGE suggestions, where enough samples were available, the 90th percentile for each zone was calculated to obtain a local NBL (LNBL). Differently from the original NBL, this local value gives more detailed water quality information accounting the hydrogeological and geochemical setting, and contaminant spatial variation. Hence, the LNBL could give more indications about the distinction between natural occurrence and

Review of epidemiological and cytogenetic studies on high background radiation area residents

International Nuclear Information System (INIS)

Iwasaki, Toshiyasu

2008-01-01

Emerging scientific knowledge in the field of radiation biology has put into question the generic use of a simple linear extrapolation of radiation effects from high to low dose or dose rate. Though the direct information of biological effects at low dose or low dose rate has been accumulated, it is still immature to mention health effects as the consequence of biological effects. As epidemiological data have been the main sources of direct information on human health effects, studies of the health of population exposed by low dose or low dose rate ionizing radiation will help to improve our understanding. In this meaning, the epidemiological studies of residents in high background radiation areas (HBRA), which are supported by us, will provide important direct information on the biological and health effects of chronic low dose rate ionizing radiation. The epidemiological results in HBRA in China showed there are no significant increases of cancer risks caused by the high background levels of ionizing radiation. From the results which come from cytogeneticl studies, the frequencies of unstable chromosomal aberrations have shown good correlation with cumulative doses in their lifetimes, which indicated it is a sensitive and informative biomarker. On the other hand, the frequencies of stable chromosomal aberrations have shown no significant difference and the frequency was much higher than that of unstable type aberrations. It suggests that mutagenic factors other than radiation contribute more than the elevated level of radiation to the induction of DNA rearrangements which could lead to the increase of cancer risk in HBRA in China. (author)

Gauging Metallicity of Diffuse Gas under an Uncertain Ionizing Radiation Field

Science.gov (United States)

Chen, Hsiao-Wen; Johnson, Sean D.; Zahedy, Fakhri S.; Rauch, Michael; Mulchaey, John S.

2017-06-01

Gas metallicity is a key quantity used to determine the physical conditions of gaseous clouds in a wide range of astronomical environments, including interstellar and intergalactic space. In particular, considerable effort in circumgalactic medium (CGM) studies focuses on metallicity measurements because gas metallicity serves as a critical discriminator for whether the observed heavy ions in the CGM originate in chemically enriched outflows or in more chemically pristine gas accreted from the intergalactic medium. However, because the gas is ionized, a necessary first step in determining CGM metallicity is to constrain the ionization state of the gas which, in addition to gas density, depends on the ultraviolet background radiation field (UVB). While it is generally acknowledged that both the intensity and spectral slope of the UVB are uncertain, the impact of an uncertain spectral slope has not been properly addressed in the literature. This Letter shows that adopting a different spectral slope can result in an order of magnitude difference in the inferred CGM metallicity. Specifically, a harder UVB spectrum leads to a higher estimated gas metallicity for a given set of observed ionic column densities. Therefore, such systematic uncertainties must be folded into the error budget for metallicity estimates of ionized gas. An initial study shows that empirical diagnostics are available for discriminating between hard and soft ionizing spectra. Applying these diagnostics helps reduce the systematic uncertainties in CGM metallicity estimates.

Gauging Metallicity of Diffuse Gas under an Uncertain Ionizing Radiation Field

Energy Technology Data Exchange (ETDEWEB)

Chen, Hsiao-Wen; Zahedy, Fakhri S. [Department of Astronomy and Astrophysics, The University of Chicago, 5640 S Ellis Avenue, Chicago, IL 60637 (United States); Johnson, Sean D. [Department of Astrophysics, Princeton University, Princeton, NJ (United States); Rauch, Michael; Mulchaey, John S., E-mail: hchen@oddjob.uchicago.edu [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

2017-06-20

Gas metallicity is a key quantity used to determine the physical conditions of gaseous clouds in a wide range of astronomical environments, including interstellar and intergalactic space. In particular, considerable effort in circumgalactic medium (CGM) studies focuses on metallicity measurements because gas metallicity serves as a critical discriminator for whether the observed heavy ions in the CGM originate in chemically enriched outflows or in more chemically pristine gas accreted from the intergalactic medium. However, because the gas is ionized, a necessary first step in determining CGM metallicity is to constrain the ionization state of the gas which, in addition to gas density, depends on the ultraviolet background radiation field (UVB). While it is generally acknowledged that both the intensity and spectral slope of the UVB are uncertain, the impact of an uncertain spectral slope has not been properly addressed in the literature. This Letter shows that adopting a different spectral slope can result in an order of magnitude difference in the inferred CGM metallicity. Specifically, a harder UVB spectrum leads to a higher estimated gas metallicity for a given set of observed ionic column densities. Therefore, such systematic uncertainties must be folded into the error budget for metallicity estimates of ionized gas. An initial study shows that empirical diagnostics are available for discriminating between hard and soft ionizing spectra. Applying these diagnostics helps reduce the systematic uncertainties in CGM metallicity estimates.

Ionizing radiation in hospitals

International Nuclear Information System (INIS)

Blok, K.; Ginkel, G. van; Leun, K. van der; Muller, H.; Oude Elferink, J.; Vesseur, A.

1985-10-01

This booklet dels with the risks of the use of ionizing radiation for people working in a hospital. It is subdivided in three parts. Part 1 treats the properties of ionizing radiation in general. In part 2 the various applications are discussed of ionizing radiation in hospitals. Part 3 indicates how a not completely safe situation may be improved. (H.W.). 14 figs.; 4 tabs

Ionization of EPA contaminants in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

Science.gov (United States)

Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

2015-06-01

Seventy-seven EPA priority environmental pollutants were analyzed using gas chromatography-mass spectrometry (GC-MS) equipped with an optimized atmospheric pressure photoionization (APPI) and an atmospheric pressure laser ionization (APLI) interface with and without dopants. The analyzed compounds included e.g., polycyclic aromatic hydrocarbons (PAHs), nitro compounds, halogenated compounds, aromatic compounds with phenolic, acidic, alcohol, and amino groups, phthalate and adipatic esters, and aliphatic ethers. Toluene, anisole, chlorobenzene, and acetone were tested as dopants. The widest range of analytes was ionized using direct APPI (66/77 compounds). The introduction of dopants decreased the amount of compounds ionized in APPI (e.g., 54/77 with toluene), but in many cases the ionization efficiency increased. While in direct APPI the formation of molecular ions via photoionization was the main ionization reaction, dopant-assisted (DA) APPI promoted ionization reactions, such as charge exchange and proton transfer. Direct APLI ionized a much smaller amount of compounds than APPI (41/77 compounds), showing selectivity towards compounds with low ionization energies (IEs) and long-lived resonantly excited intermediate states. DA-APLI, however, was able to ionize a higher amount of compounds (e.g. 51/77 with toluene), as the ionization took place entirely through dopant-assisted ion/molecule reactions similar to those in DA-APPI. Best ionization efficiency in APPI and APLI (both direct and DA) was obtained for PAHs and aromatics with O- and N-functionalities, whereas nitro compounds and aliphatic ethers were the most difficult to ionize. Halogenated aromatics and esters were (mainly) ionized in APPI, but not in APLI.

Position sensitive detection of neutrons in high radiation background field.

Science.gov (United States)

Vavrik, D; Jakubek, J; Pospisil, S; Vacik, J

2014-01-01

We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e(-) radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm(2)) spectroscopic Timepix detector adapted for neutron detection utilizing very thin (10)B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10(-4).

Remedial action in areas of enhanced natural background radiation levels (with particular emphasis in areas with mineral sand mining residues)

International Nuclear Information System (INIS)

Swindon, T.N.

1985-01-01

In areas where individuals may receive doses from natural background sources which are higher than those received in areas of normal background radiation, it may be considered desirable that some remedial action be taken to reduce those doses. Contributions to these higher doses may be through high gamma ray fields from the ground or from the use of local building materials, the intake of food or water derived from the areas or of food covered with dust from the areas, the ingestion of dirt and the inhalation of dust, and radon or thoron. Guidelines for remedial action in areas where residues from mineral sand mining and processing have been deposited are given

Miniature ionization chamber

International Nuclear Information System (INIS)

Alexeev, V.I.; Emelyanov, I.Y.; Ivanov, V.M.; Konstantinov, L.V.; Lysikov, B.V.; Postnikov, V.V.; Rybakov, J.V.

1976-01-01

A miniature ionization chamber having a gas-filled housing which accommodates a guard electrode made in the form of a hollow perforated cylinder is described. The cylinder is electrically associated with the intermediate coaxial conductor of a triaxial cable used as the lead-in of the ionization chamber. The gas-filled housing of the ionization chamber also accommodates a collecting electrode shaped as a rod electrically connected to the center conductor of the cable and to tubular members. The rod is disposed internally of the guard electrode and is electrically connected, by means of jumpers passing through the holes in the guard electrode, to the tubular members. The tubular members embrace the guard electrode and are spaced a certain distance apart along its entire length. Arranged intermediate of these tubular members are spacers secured to the guard electrode and fixing the collecting electrode throughout its length with respect to the housing of the ionization chamber

Concerning evaluation of eco-geochemical background in remediation strategy

Science.gov (United States)

Korobova, Elena; Romanov, Sergey

2015-04-01

The geochemical concept of biosphere developed by V.I. Vernadsky states the geological role of the living organisms in the course of their active chemical interaction with the inert matter (Vernadsky, 1926, 1960). Basing on this theory it is reasonable to suggest that coevolution of living organisms and their environment led to development of the dynamically stable biogeocenoses precisely adequate to their geochemical environment. Soil cover was treated by V.I. Vernadsky as a balanced bio-inert matter resulting from this interaction. Appearance of human mind and then a civilization led to global expansion of human beings, first able to survive in unfavorable geochemical conditions and then starting chemical transformation of the environment to satisfy the growing demands of mankind in food and energy. The residence in unfavorable environment and local contamination was followed by appearance of endemic diseases of plants, animals and man. Therefore zonal, regional and local chemical composition of the soil cover formed in natural conditions may be used for estimation of the optimum geochemical background, most adequate for the corresponding zonal biogeocenoses and species. Moreover, the natural geochemical background and technogenic fields have unequal spatial structure and this facilitates their identification that may be relatively easy realized in remediation strategy. On the assumption of the foregoing, the adequate methodical approach to remediation of technogenically affected areas should account of the interaction of the existing natural and the newly formed technogenic geochemical fields and include the following steps: 1) the study and mapping of geochemical structure of the natural geochemical background basing on soil maps; 2) the study of contaminants and mapping spatial distribution of technogenic releases; 3) construction of risk maps for the target risk groups with due regard to natural ecological threshold concentration in context of risk degree for

Increased ionization rate in laser enrichment

International Nuclear Information System (INIS)

Janes, G.S.; Pike, G.T.

1977-01-01

A system employing multiple, upper excitation levels in a technique for isotopically selective ionization to improve the ionization efficiency is described. Laser radiation is employed to excite particles with isotopic selectivity. Excitation is produced to a plurality of excited states below the ionization level with the result of increasing the number of available excited particles for ionization and thereby increasing the ionization cross section for improved system efficiency

Electrospray ionization and matrix assisted laser desorption/ionization mass spectrometry: powerful analytical tools in recombinant protein chemistry

DEFF Research Database (Denmark)

Andersen, Jens S.; Svensson, B; Roepstorff, P

1996-01-01

Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy is presen......Electrospray ionization and matrix assisted laser desorption/ionization are effective ionization methods for mass spectrometry of biomolecules. Here we describe the capabilities of these methods for peptide and protein characterization in biotechnology. An integrated analytical strategy...... is presented encompassing protein characterization prior to and after cloning of the corresponding gene....

Novel Laser Ignition Technique Using Dual-Pulse Pre-Ionization

Science.gov (United States)

Dumitrache, Ciprian

Recent advances in the development of compact high power laser sources and fiber optic delivery of giant pulses have generated a renewed interest in laser ignition. The non-intrusive nature of laser ignition gives it a set of unique characteristics over the well-established capacitive discharge devices (or spark plugs) that are currently used as ignition sources in engines. Overall, the use of laser ignition has been shown to have a positive impact on engine operation leading to a reduction in NOx emission, fuel saving and an increased operational envelope of current engines. Conventionally, laser ignition is achieved by tightly focusing a high-power q-switched laser pulse until the optical intensity at the focus is high enough to breakdown the gas molecules. This leads to the formation of a spark that serves as the ignition source in engines. However, there are certain disadvantages associated with this ignition method. This ionization approach is energetically inefficient as the medium is transparent to the laser radiation until the laser intensity is high enough to cause gas breakdown. As a consequence, very high energies are required for ignition (about an order of magnitude higher energy than capacitive plugs at stoichiometric conditions). Additionally, the fluid flow induced during the plasma recombination generates high vorticity leading to high rates of flame stretching. In this work, we are addressing some of the aforementioned disadvantages of laser ignition by developing a novel approach based on a dual-pulse pre-ionization scheme. The new technique works by decoupling the effect of the two ionization mechanisms governing plasma formation: multiphoton ionization (MPI) and electron avalanche ionization (EAI). An UV nanosecond pulse (lambda = 266 nm) is used to generate initial ionization through MPI. This is followed by an overlapped NIR nanosecond pulse (lambda = 1064 nm) that adds energy into the pre-ionized mixture into a controlled manner until the

A Comparison of Alternating Current and Direct Current Electrospray Ionization for Mass Spectrometry

Science.gov (United States)

Sarver, Scott A.; Chetwani, Nishant; Dovichi, Norman J.; Go, David B.; Gartner, Carlos A.

2014-04-01

A series of studies comparing the performance of alternating current electrospray ionization (AC ESI) mass spectrometry (MS) and direct current electrospray ionization (DC ESI) MS have been conducted, exploring the absolute signal intensity and signal-to-background ratios produced by both methods using caffeine and a model peptide as targets. Because the high-voltage AC signal was more susceptible to generating gas discharges, the operating voltage range of AC ESI was significantly smaller than that for DC ESI, such that the absolute signal intensities produced by DC ESI at peak voltages were one to two orders of magnitude greater than those for AC ESI. Using an electronegative nebulizing gas, sulfur hexafluoride (SF6), instead of nitrogen (N2) increased the operating range of AC ESI by ~50 %, but did not appreciably improve signal intensities. While DC ESI generated far greater signal intensities, both ionization methods produced comparable signal-to-background noise, with AC ESI spectra appearing qualitatively cleaner. A quantitative calibration analysis was performed for two analytes, caffeine and the peptide MRFA. AC ESI utilizing SF6 outperforms all other techniques for the detection of MRFA, producing chromatographic limits of detection nearly one order of magnitude lower than that of DC ESI utilizing N2, and one-half that of DC ESI utilizing SF6. However, DC ESI outperforms AC ESI for the analysis of caffeine, indicating that improvements in spectral quality may benefit certain compounds or classes of compounds, on an individual basis.

The VIMOS Ultra Deep Survey: Nature, ISM properties, and ionizing spectra of CIII]λ1909 emitters at z = 2-4

Science.gov (United States)

Nakajima, K.; Schaerer, D.; Le Fèvre, O.; Amorín, R.; Talia, M.; Lemaux, B. C.; Tasca, L. A. M.; Vanzella, E.; Zamorani, G.; Bardelli, S.; Grazian, A.; Guaita, L.; Hathi, N. P.; Pentericci, L.; Zucca, E.

2018-05-01

for galaxies with EW(CIII) = 10-20 Å is low, Z = 0.02-0.2 Z⊙, and the ionization parameter higher (logU -1.7) than the average star-forming galaxy. To explain the average UV observations of the strongest but rarest [CIII] emitters (EW([CIII]) > 20 Å), we find that stellar photoionization is clearly insufficient. A radiation field consisting of a mix of a young stellar population (logξion/erg-1 Hz 25.7) plus an AGN component is required. Furthermore an enhanced C/O abundance ratio (up to the solar value) is needed for metallicities Z = 0.1-0.2 Z⊙ and logU = -1.7 to - 1.5. Conclusions: A large grid of photoionization models has allowed us to propose new diagnostic diagrams to classify the nature of the ionizing radiation field (star formation or AGN) of distant galaxies using UV emission lines, and to constrain their ISM properties. We have applied this grid to a sample of [CIII]-emitting galaxies at z = 2-4 detected in VUDS, finding a range of physical properties and clear evidence for significant AGN contribution in rare sources with very strong [CIII] emission. The UV diagnostics we propose should also serve as an important basis for the interpretation of upcoming observations of high-redshift galaxies. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Program 185.A-0791.JSPS Overseas Research Fellow.

INTERSTELLAR METASTABLE HELIUM ABSORPTION AS A PROBE OF THE COSMIC-RAY IONIZATION RATE

International Nuclear Information System (INIS)

Indriolo, Nick; McCall, Benjamin J.; Hobbs, L. M.; Hinkle, K. H.

2009-01-01

The ionization rate of interstellar material by cosmic rays has been a major source of controversy, with different estimates varying by three orders of magnitude. Observational constraints of this rate have all depended on analyzing the chemistry of various molecules that are produced following cosmic-ray ionization, and in many cases these analyses contain significant uncertainties. Even in the simplest case (H + 3 ), the derived ionization rate depends on an (uncertain) estimate of the absorption path length. In this paper, we examine the feasibility of inferring the cosmic-ray ionization rate using the 10830 A absorption line of metastable helium. Observations through the diffuse clouds toward HD 183143 are presented, but yield only an upper limit on the metastable helium column density. A thorough investigation of He + chemistry reveals that only a small fraction of He + will recombine into the triplet state and populate the metastable level. In addition, excitation to the triplet manifold of helium by secondary electrons must be accounted for as it is the dominant mechanism which produces He* in some environments. Incorporating these various formation and destruction pathways, we derive new equations for the steady state abundance of metastable helium. Using these equations in concert with our observations, we find ζ He -15 s -1 , an upper limit about 5 times larger than the ionization rate previously inferred for this sight line using H + 3 . While observations of interstellar He* are extremely difficult at present, and the background chemistry is not nearly as simple as previously thought, potential future observations of metastable helium would provide an independent check on the cosmic-ray ionization rate derived from H + 3 in diffuse molecular clouds, and, perhaps more importantly, allow the first direct measurements of the ionization rate in diffuse atomic clouds.

Epigenetic effects of ionizing radiation

International Nuclear Information System (INIS)

EI-Naggar, A.M.

2007-01-01

Data generated during the last three decades provide evidence of Epigenetic Effects that ave-induced by ionizing radiation, particularly those of high LET values, and low level dose exposures. Epigenesist is defined as the stepwise process by which genetic information, as modified by environmental influences, is translated into the substance and behavior of cells, tissues, organism.The epigenetic effects cited in the literature are essentially classified into fine types depending on the type and nature of the effect induced.The most accepted postulation, for the occurrence of these epigenetic effects, is a radiation induced bio electric disturbances in the environment of the non-irradiated cellular volume. This will trigger signals that will induce effects in the unirradiated cells.The epigenetic effects referenced in the literature up to date are five types; namely, Genomic Instability, Bystander. Effects, Clastogenic Plasma Factors,, Abscopal Effects, and Tran generational Effects.The demonstration of Epigenetic Effects associated with exposure to ionizing radiation indicates the need to re- examine the concept of radiation dose and target size. Also an improved understanding of qualifiring and quantifying radiation risk estimates may be attained. Also, a more logical means to understand the underlying mechanisms of radiation induced carcinogenic transformation of cells

Multiple ionization and coupling effects in L-subshell ionization of heavy atoms by oxygen ions

International Nuclear Information System (INIS)

Pajek, M.; Banas, D.; Semaniak, J.; Braziewicz, J.; Majewska, U.; Chojnacki, S.; Czyzewski, T.; Fijal, I.; Jaskola, M.; Glombik, A.; Kretschmer, W.; Trautmann, D.; Lapicki, G.; Mukoyama, T.

2003-01-01

The multiple-ionization and coupling effects in L-shell ionization of atoms by heavy-ion impact have been studied by measuring the L x-ray production cross sections in solid targets of Au, Bi, Th, and U bombarded by oxygen ions in the energy range 6.4-70 MeV. The measured L x-ray spectra were analyzed using the recently proposed method accounting for the multiple-ionization effects, such as x-ray line shifting and broadening, which enables one to obtain the ionization probabilities for outer shells. The L-subshell ionization cross sections have been obtained from measured x-ray production cross sections for resolved Lα 1,2 , Lγ 1 , and Lγ 2,3 transitions using the L-shell fluorescence and Coster-Kronig yields being substantially modified by the multiple ionization in the M and N shells. In particular, the effect of closing of strong L 1 -L 3 M 4,5 Coster-Kronig transitions in multiple-ionized atoms was evidenced and discussed. The experimental ionization cross sections for the L 1 , L 2 , and L 3 subshells have been compared with the predictions of the semiclassical approximation (SCA) and the ECPSSR theory that includes the corrections for the binding-polarization effect within the perturbed stationary states approximation, the projecticle energy loss, and Coulomb deflection effects as well as the relativistic description of inner-shell electrons. These approaches were further modified to include the L-subshell couplings within the ''coupled-subshell model'' (CSM). Both approaches, when modified for the coupling effects, are in better agreement with the data. Particularly, the predictions of the SCA-CSM calculations reproduce the experimental L-subshell ionization cross section reasonably well. Remaining discrepancies are discussed qualitatively, in terms of further modifications of the L-shell decay rates caused by a change of electronic wave functions in multiple-ionized atoms

Dual ionization chamber

International Nuclear Information System (INIS)

Mallory, J.; Turlej, Z.

1981-01-01

Dual ionization chambers are provided for use with an electronic smoke detector. The chambers are separated by electrically-conductive partition. A single radiation source extends through the partition into both chambers, ionizing the air in each. The mid-point current of the device may be balanced by adjusting the position of the source

Resonance ionization scheme development for europium

Energy Technology Data Exchange (ETDEWEB)

Chrysalidis, K., E-mail: katerina.chrysalidis@cern.ch; Goodacre, T. Day; Fedosseev, V. N.; Marsh, B. A. [CERN (Switzerland); Naubereit, P. [Johannes Gutenberg-Universität, Institiut für Physik (Germany); Rothe, S.; Seiffert, C. [CERN (Switzerland); Kron, T.; Wendt, K. [Johannes Gutenberg-Universität, Institiut für Physik (Germany)

2017-11-15

Odd-parity autoionizing states of europium have been investigated by resonance ionization spectroscopy via two-step, two-resonance excitations. The aim of this work was to establish ionization schemes specifically suited for europium ion beam production using the ISOLDE Resonance Ionization Laser Ion Source (RILIS). 13 new RILIS-compatible ionization schemes are proposed. The scheme development was the first application of the Photo Ionization Spectroscopy Apparatus (PISA) which has recently been integrated into the RILIS setup.

Nanoparticle assisted laser desorption/ionization mass spectrometry for small molecule analytes.

Science.gov (United States)

Abdelhamid, Hani Nasser

2018-03-01

Nanoparticle assisted laser desorption/ionization mass spectrometry (NPs-ALDI-MS) shows remarkable characteristics and has a promising future in terms of real sample analysis. The incorporation of NPs can advance several methods including surface assisted LDI-MS, and surface enhanced LDI-MS. These methods have advanced the detection of many thermally labile and nonvolatile biomolecules. Nanoparticles circumvent the drawbacks of conventional organic matrices for the analysis of small molecules. In most cases, NPs offer a clear background without interfering peaks, absence of fragmentation of thermally labile molecules, and allow the ionization of species with weak noncovalent interactions. Furthermore, an enhancement in sensitivity and selectivity can be achieved. NPs enable straightforward analysis of target species in a complex sample. This review (with 239 refs.) covers the progress made in laser-based mass spectrometry in combination with the use of metallic NPs (such as AuNPs, AgNPs, PtNPs, and PdNPs), NPs consisting of oxides and chalcogenides, silicon-based NPs, carbon-based nanomaterials, quantum dots, and metal-organic frameworks. Graphical abstract An overview is given on nanomaterials for use in surface-assisted laser desorption/ionization mass spectrometry of small molecules.

Modulation of the Object/Background Interaction by Spatial Frequency

Directory of Open Access Journals (Sweden)

Yanju Ren

2011-05-01

Full Text Available With regard to the relationship between object and background perception in the natural scene images, functional isolation hypothesis and interactive hypothesis were proposed. Based on previous studies, the present study investigated the role of spatial frequency in the relationship between object and background perception in the natural scene images. In three experiments, participants reported the object, background, or both after seeing each picture for 500 ms followed by a mask. The authors found that (a backgrounds were identified more accurately when they contained a consistent rather than an inconsistent object, independently of spatial frequency; (b objects were identified more accurately in a consistent than an inconsistent background under the condition of low spatial frequencies but not high spatial frequencies; (c spatial frequency modulation remained when both objects and backgrounds were reported simultaneously. The authors conclude that object/background interaction is partially dependent on spatial frequency.

Effects of easily ionizable elements on the liquid sampling-atmospheric pressure glow discharge

International Nuclear Information System (INIS)

Venzie, Jacob L.; Marcus, R. Kenneth

2006-01-01

A series of studies has been undertaken to determine the susceptibility of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) atomic emission source to easily ionizable element (EIE) effects. The initial portions of the study involved monitoring the voltage drop across the plasma as a function of the pH to ascertain whether or not the conductivity of the liquid eluent alters the plasma energetics and subsequently the analyte signal strength. It was found that altering the pH (0.0 to 2.0) in the sample matrix did not significantly change the discharge voltage. The emission signal intensities for Cu(I) 327.4 nm, Mo(I) 344.7 nm, Sc(I) 326.9 nm and Hg(I) 253.6 nm were measured as a function of the easily ionizable element (sodium and calcium) concentration in the injection matrix. A range of 0.0 to 0.1% (w/v) EIE in the sample matrix did not cause a significant change in the Cu, Sc, and Mo signal-to-background ratios, with only a slight change noted for Hg. In addition to this test of analyte response, the plasma energetics as a function of EIE concentration are assessed using the ratio of Mg(II) to Mg(I) (280.2 nm and 285.2 nm, respectively) intensities. The Mg(II)/Mg(I) ratio showed that the plasma energetics did not change significantly over the same range of EIE addition. These results are best explained by the electrolytic nature of the eluent acting as an ionic (and perhaps spectrochemical) buffer

Role of Ionizing Radiation in Neurodegenerative Diseases

Directory of Open Access Journals (Sweden)

Neel K. Sharma

2018-05-01

Full Text Available Ionizing radiation (IR from terrestrial sources is continually an unprotected peril to human beings. However, the medical radiation and global radiation background are main contributors to human exposure and causes of radiation sickness. At high-dose exposures acute radiation sickness occurs, whereas chronic effects may persist for a number of years. Radiation can increase many circulatory, age related and neurodegenerative diseases. Neurodegenerative diseases occur a long time after exposure to radiation, as demonstrated in atomic bomb survivors, and are still controversial. This review discuss the role of IR in neurodegenerative diseases and proposes an association between neurodegenerative diseases and exposure to IR.

Role of Ionizing Radiation in Neurodegenerative Diseases

Science.gov (United States)

Sharma, Neel K.; Sharma, Rupali; Mathur, Deepali; Sharad, Shashwat; Minhas, Gillipsie; Bhatia, Kulsajan; Anand, Akshay; Ghosh, Sanchita P.

2018-01-01

Ionizing radiation (IR) from terrestrial sources is continually an unprotected peril to human beings. However, the medical radiation and global radiation background are main contributors to human exposure and causes of radiation sickness. At high-dose exposures acute radiation sickness occurs, whereas chronic effects may persist for a number of years. Radiation can increase many circulatory, age related and neurodegenerative diseases. Neurodegenerative diseases occur a long time after exposure to radiation, as demonstrated in atomic bomb survivors, and are still controversial. This review discuss the role of IR in neurodegenerative diseases and proposes an association between neurodegenerative diseases and exposure to IR. PMID:29867445

Nonproliferation and safeguarding via ionization detection

International Nuclear Information System (INIS)

Koster, J.E.; Johnson, J.P.; Steadman, P.

1995-01-01

A significant signature of the presence of special nuclear material (SNM) is ionizing radiation. SNM naturally decays with the emission of alpha particles, gamma rays, and neutrons. Detecting and monitoring these emissions is an important capability for international safeguards. A new detection method collects the ions produced by such radiation in ambient air. Alpha particles in particular are specific to heavy nuclei but have very short range. The ions produced by an alpha, however, can be transported tens of meters to an ion detector. These new monitors are rugged, very sensitive, respond in real time, and in most cases are quite portable

K-shell ionization by antiprotons

International Nuclear Information System (INIS)

Mehler, G.; Mueller, B.; Greiner, W.; Soff, G.

1987-01-01

We present first calculations for the impact parameter dependence of K-shell ionization rates in anti pCu and in anti pAg collisions at various projectile energies. We show that the effect of the attractive Coulomb potential on the Rutherford trajectory and the anti-binding effect caused by the negative charge of the antiproton result in a considerable increase of the ionization probability. Total ionization cross-sections for proton and antiproton projectiles are compared with each other and with experimental ionization cross-sections for protons. (orig.)

Natural sources of ionizing radiation in Europe

International Nuclear Information System (INIS)

Green, B.M.R.; Hughes, J.S.; Lomas, P.R.

1993-01-01

This publication maps levels of radiation of natural origin throughout the European Community (except in the Lander of the former German Democratic Republic), in Scandinavia and in Austria. The booklet explains in simple terms the basic properties and origin of different types of radiation (cosmic rays, gamma rays and radon) and their contribution to the overall exposure of the population. A glossary, a list of administrative regions used in the maps and detailed references to the data for each country are included

Electron-Impact Ionization and Dissociative Ionization of Biomolecules

Science.gov (United States)

Huo, Winifred M.; Chaban, Galina M.; Dateo, Christopher E.

2006-01-01

It is well recognized that secondary electrons play an important role in radiation damage to humans. Particularly important is the damage of DNA by electrons, potentially leading to mutagenesis. Molecular-level study of electron interaction with DNA provides information on the damage pathways and dominant mechanisms. Our study of electron-impact ionization of DNA fragments uses the improved binary-encounter dipole model and covers DNA bases, sugar phosphate backbone, and nucleotides. An additivity principle is observed. For example, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C3(sup prime)- and C5 (sup prime)-deoxyribose-phospate cross sections, differing by less than 5%. Investigation of tandem double lesion initiated by electron-impact dissociative ionization of guanine, followed by proton reaction with the cytosine in the Watson-Crick pair, is currently being studied to see if tandem double lesion can be initiated by electron impact. Up to now only OH-induced tandem double lesion has been studied.

Survey of Gamma Dose and Radon Exhalation Rate from Soil Surface of High Background Natural Radiation Areas in Ramsar, Iran

Directory of Open Access Journals (Sweden)

Rouhollah Dehghani

2013-09-01

Full Text Available Background: Radon is a radioactive gas and the second leading cause of death due to lung cancer after smoking. Ramsar is known for having the highest levels of natural background radiation on earth. Materials and Methods: In this research study, 50 stations of high radioactivity areas of Ramsar were selected in warm season of the year. Then gamma dose and radon exhalation rate were measured.Results: Results showed that gamma dose and radon exhalation rate were in the range of 51-7100 nSv/hr and 9-15370 mBq/m2s, respectively.Conclusion: Compare to the worldwide average 16 mBq/m2s, estimated average annual effective of Radon exhalation rate in the study area is too high.

The high-sensitive magnetic levitated electrode ionization chamber of the noncontacting type

International Nuclear Information System (INIS)

Kawaguchi, Toshiro; Yoshimura, Atsushi

1999-01-01

There are two types of ionization chamber using magnetically levitated electrode: one is that by Tanaka et al. and the other, by authors'. The latter lacks the sensitivity relative to the former and thereby to solve the problem, authors made an improvement so that the electrode charge could be readout by noncontact after the leviated electrode was electrified by noncontact for an interval. This new type ionization chamber made it possible to measure the quite low dose radiation with stability and high sensitivity. Actually, the electrode was suspended by the teflon thread fixed on the steel cup levitated magnetically in the ionization chamber of which wall was covered by Al and equipped with an electrostatic charger for the electrode by noncontact. After measurement, the electrode was moved in the Faraday cage placed under the chamber to readout the voltage. For operation conditions of the apparatus, observation was done on the relationship between ionization current by 137 Cs and the applied voltage. For actual measurement, ionizations by low dose γ ray derived from KCl which containing 40 K in a small amount and by Rn at the fine and rainy days were measured. The exposure rate by KCl (500 g bottle) was found to be 12.7 x 10 -10 C/kg·h with the background value of 9.8 x 10 -10 . Rn concentrations in the air were 112.3 and 18.34 Bq/m 3 for 1 hr in the rainy and fine day, respectively, in Fukuoka City. (K.H.)

Leukaemia risks and exposure to ionizing radiations. ASN seminar, Tuesday, June 9, 2015, report

International Nuclear Information System (INIS)

Niel, Jean-Christophe; Samain, Jean-Paul; Colonna, Marc; Maynadie, Marc; Richardson, David; Bey, Pierre; Leuraud, Klervi; Laurier, Dominique; Hemon, Denis; Spycher, Ben; Kosti, Ourania; Bouville, Andre; Grosche, Bernd; Ziegelberger, Gunde; Kesminiene, Ausrele; Clavel, Jacqueline; Smeesters, Patrick; Murith, Christophe

2015-08-01

This seminar aims at proposing a review of present knowledge on leukaemia risks for children and adults associated with ionizing radiations, and at sharing knowledge between experts. After an introduction which outlined the interest of the ASN in research issues, and the importance awarded by the ASN to the variety of points of view, a first session addressed leukaemia and exposures to ionizing radiations. The contributions addressed some general aspects (an overview of leukaemia in France, the different types of adult and child leukaemia), leukaemia and acute exposures to ionizing radiations (ionizing radiation and leukaemia among Japanese bomb survivors, risks of leukaemia after radiotherapy), leukaemia and chronic exposures to ionizing radiations (assessment of epidemiological studies for adult chronic exposures). The second session addressed childhood leukaemia and ionizing radiations. The contributions of this second session more particularly addressed the following topics: childhood leukaemia and natural radioactivity (French studies, synthesis of international studies and a new Swiss study), childhood leukaemia and proximity of nuclear base installations (assessment of national and international studies, analysis of cancer risks in populations near nuclear facilities in the US, calculation of dose at the medulla as example of dosimetry of ionizing radiations and leukaemia, conclusions of the 2012 MELODI workshop), childhood leukaemia and scanner (recent results and perspectives), childhood leukaemia and other risk factors (etiology of childhood leukaemia - presentation of French studies initiated by the INSERM, and presentation of studies initiated by BfS)

A single-electron picture based on the multiconfiguration time-dependent Hartree-Fock method: application to the anisotropic ionization and subsequent high-harmonic generation of the CO molecule

Science.gov (United States)

Ohmura, S.; Kato, T.; Oyamada, T.; Koseki, S.; Ohmura, H.; Kono, H.

2018-02-01

The mechanisms of anisotropic near-IR tunnel ionization and high-order harmonic generation (HHG) in a CO molecule are theoretically investigated by using the multiconfiguration time-dependent Hartree-Fock (MCTDHF) method developed for the simulation of multielectron dynamics of molecules. The multielectron dynamics obtained by numerically solving the equations of motion (EOMs) in the MCTDHF method is converted to a single orbital picture in the natural orbital representation where the first-order reduced density matrix is diagonalized. The ionization through each natural orbital is examined and the process of HHG is classified into different optical paths designated by a combinations of initial, intermediate and final natural orbitals. The EOMs for natural spin-orbitals are also derived within the framework of the MCTDHF, which maintains the first-order reduced density matrix to be a diagonal one throughout the time propagation of a many-electron wave function. The orbital dependent, time-dependent effective potentials that govern the dynamics of respective time-dependent natural orbitals are deduced from the derived EOMs, of which the temporal variation can be used to interpret the motion of the electron density associated with each natural spin-orbital. The roles of the orbital shape, multiorbital ionization, linear Stark effect and multielectron interaction in the ionization and HHG of a CO molecule are revealed by the effective potentials obtained. When the laser electric field points to the nucleus O from C, tunnel ionization from the C atom side is enhanced; a hump structure originating from multielectron interaction is then formed on the top of the field-induced distorted barrier of the HOMO effective potential. This hump formation, responsible for the directional anisotropy of tunnel ionization, restrains the influence of the linear Stark effect on the energy shifts of bound states.

Fog camera to visualize ionizing charged particles

International Nuclear Information System (INIS)

Trujillo A, L.; Rodriguez R, N. I.; Vega C, H. R.

2014-10-01

The human being can not perceive the different types of ionizing radiation, natural or artificial, present in the nature, for what appropriate detection systems have been developed according to the sensibility to certain radiation type and certain energy type. The objective of this work was to build a fog camera to visualize the traces, and to identify the trajectories, produced by charged particles with high energy, coming mainly of the cosmic rays. The origin of the cosmic rays comes from the solar radiation generated by solar eruptions where the protons compose most of this radiation. It also comes, of the galactic radiation which is composed mainly of charged particles and gamma rays that comes from outside of the solar system. These radiation types have energy time millions higher that those detected in the earth surface, being more important as the height on the sea level increases. These particles in their interaction produce secondary particles that are detectable by means of this cameras type. The camera operates by means of a saturated atmosphere of alcohol vapor. In the moment in that a charged particle crosses the cold area of the atmosphere, the medium is ionized and the particle acts like a condensation nucleus of the alcohol vapor, leaving a visible trace of its trajectory. The built camera was very stable, allowing the detection in continuous form and the observation of diverse events. (Author)

Bystander Effects of Ionizing Radiation

Energy Technology Data Exchange (ETDEWEB)

Little, John B. [Harvard T.H. Chan School of Public Health, Boston, MA (United States). Dept. of Genetics and Complex Diseases

2017-01-17

The objectives of this grant renewal are to provide administrative support and travel funds to allow the continued participation of the principal investigator (Dr. John B. Little) as an advisor to research initiated by several research fellows from his laboratory. The actual research will be carried out under the direction of Dr. Hatsumi Nagasawa with the collaboration of Dr. Joel Bedford at the Colorado State University, and by Drs. Edouard Azzam and Sonia de Toledo at the University of Medicine and Dentistry of New Jersey. Dr. Little will advise on the planning of experiments and development of experimental protocols, the analysis of data, and the preparation of manuscripts for publication. The Specific Aims for several of the planned experiments include: 1) to extend studies of the role of recombinational repair in the bystander effect by examining other genes in this pathway and cell lines deficient in excision repair; 2) to continue studies to determine the nature of the damage signal transmitted to bystander cells including the expression of several connexins in the bystander response, and the extent to which the enhanced oxidative metabolism observed in bystander cells may relate to the nature of the transmitted bystander signal; 3) to utilize a genome-wide approach to examine the genetic basis for the hypersensitivity to ionization we have observed in unaffected parents of patients with hereditary retinoblastoma, as well as from a group of apparently normal individuals that show similar radiosensitivity; 4) to complete studies concerning the induction of high frequencies of cells with massive chromosome damage in clonal derivatives of p53 and p21 knockout mouse cell lines; in particular to examine the role of telomere changes in this phenomenon. Overall, the results of these studies should enhance our understanding of the risk of low-dose exposures to ionizing radiation, including human populations to residential radon as well as occupational exposures.

Bystander Effects of Ionizing Radiation

International Nuclear Information System (INIS)

Little, John B.

2017-01-01

The objectives of this grant renewal are to provide administrative support and travel funds to allow the continued participation of the principal investigator (Dr. John B. Little) as an advisor to research initiated by several research fellows from his laboratory. The actual research will be carried out under the direction of Dr. Hatsumi Nagasawa with the collaboration of Dr. Joel Bedford at the Colorado State University, and by Drs. Edouard Azzam and Sonia de Toledo at the University of Medicine and Dentistry of New Jersey. Dr. Little will advise on the planning of experiments and development of experimental protocols, the analysis of data, and the preparation of manuscripts for publication. The Specific Aims for several of the planned experiments include: 1) to extend studies of the role of recombinational repair in the bystander effect by examining other genes in this pathway and cell lines deficient in excision repair; 2) to continue studies to determine the nature of the damage signal transmitted to bystander cells including the expression of several connexins in the bystander response, and the extent to which the enhanced oxidative metabolism observed in bystander cells may relate to the nature of the transmitted bystander signal; 3) to utilize a genome-wide approach to examine the genetic basis for the hypersensitivity to ionization we have observed in unaffected parents of patients with hereditary retinoblastoma, as well as from a group of apparently normal individuals that show similar radiosensitivity; 4) to complete studies concerning the induction of high frequencies of cells with massive chromosome damage in clonal derivatives of p53 and p21 knockout mouse cell lines; in particular to examine the role of telomere changes in this phenomenon. Overall, the results of these studies should enhance our understanding of the risk of low-dose exposures to ionizing radiation, including human populations to residential radon as well as occupational exposures.

The effect of ionizing radiation on intraocular lenses

International Nuclear Information System (INIS)

Ellerin, Bruce E.; Nisce, Lourdes Z.; Roberts, Calvin W.; Thornell, Cliff; Sabbas, Albert; Wang Huili; Li, P. Mark; Nori, Dattatreyudu

2001-01-01

Background: The native crystalline lens is the principal shield against ultraviolet radiation (UV), damage to the human retina. Every year in the United States, more than one million patients undergo removal of the natural lens in the course of cataract surgery (phakectomy), at which time an intraocular lens (IOL) is placed in the lens capsule. The IOL thenceforth serves as the principal barrier to ultraviolet radiation over the life of the implant, potentially for decades. The synthetic organic molecules of which IOLs are composed offer little UV protection unless ultraviolet-absorbing chromophores are incorporated into the lens material during manufacture. However, chromophores are alkenes potentially subject to radiolytic degradation. It is unknown whether ionizing radiation at clinical doses (e.g., to the brain or in the head-and-neck region) affects the UV-absorbing capacity of chromophore-bearing IOLs and consequently exposes the retina to potentially chronic UV damage. In addition, the polymers of which IOLs are composed are themselves subject to radiation damage, which theoretically might result in optical distortion in the visible light range. Objective: To determine whether megavoltage photon ionizing radiation alters the absorption spectra of ultraviolet-shielding polymethylmethacrylate (PMMA) and organopolysiloxane (silicone) intraocular lenses (IOLs) in the UV (280 nm ≤ λ < 400 nm), visible (400 nm ≤ λ ≤ 700 nm), and low-end near-infrared (700 nm < λ ≤ 830 nm) ranges. Design: Prospective, nonrandomized trial of dose-paired IOL cohorts. Methods: Fourteen IOLs, seven of PMMA (Chiron 6842B) and seven of silicone (IOLAB L141U), were paired and examined for absorption spectra in 1-nm intervals over the range λ = 280-830 nm on a Cary 400 deuterium and quartz halogen source-lamp UV/visible spectrophotometer before and after undergoing megavoltage ionizing irradiation to doses of 2, 5, 10, 20, 40, 60, and 100 Gray, respectively. Because of

A geophysical tour of high background radiation areas of the world

International Nuclear Information System (INIS)

Krishnan, D.; Kher, R.K.; Nambi, K.S.V.

1995-01-01

A comparison of the findings including health effects in four major high natural background areas of the world are given. Such high background areas could prove to be a radiation ecology laboratory gifted by nature and provide further insight in the relation of radiation, natural or otherwise and human health. 3 refs., 2 tabs

Relativistic theory of electron-impact ionization

International Nuclear Information System (INIS)

Rosenberg, Leonard

2010-01-01

A relativistic version of an earlier, non-relativistic, formulation of the theory of ionization of an atomic system by electron impact is presented. With a time-independent resolvent operator taken as the basis for the dynamics, a wave equation is derived for a system with open channels consisting of two positive-energy electrons in an external field generated by the residual ion. Virtual intermediate states can be accounted for by the effective Hamiltonian that appears in the wave equation and which in principle may be constructed perturbatively. The asymptotic form of the wavefunction, modified by the effects of the long-range Coulomb interactions of the two electrons in the external field, is derived. These electrons are constrained, by projection operators which appear naturally in the theory, to propagate in positive-energy states only. The long-range Coulomb effects take the form of phase factors similar to those that are found in the non-relativistic version of the theory. With the boundary conditions established, an integral identity for the ionization amplitude is derived, and used to set up a distorted-wave Born expansion for the transition amplitude involving Coulomb-modified propagating waves.

COMPARISON OF NATURAL BACKGROUND DOSE RATES FOR RESIDENTS OF THE AMARGOSA VALLEY, NV, TO THOSE IN LEADVILLE, CO, AND THE STATES OF COLORADO AND NEVADA

International Nuclear Information System (INIS)

D. Moeller and L. C. Sun

2006-01-01

In the latter half of 2005, the U.S. Environmental Protection Agency (USEPA) published a Proposed Rule (40 CFR Part 197) for establishing a dose rate standard for limiting radionuclide releases from the proposed Yucca Mountain high-level radioactive waste repository during the time period from 10 4 to 10 6 years after closure. The proposed standard was based on the difference in the estimated total dose rate from natural background in the Amargosa Valley and the ''average annual background radiation'' for the State of Colorado. As defined by the USEPA, ''natural background radiation consists of external exposures from cosmic and terrestrial sources, and internal exposures from indoor exposures to naturally-occurring radon''. On the basis of its assessments, the USEPA estimated that the difference in the dose rate in the two identified areas was 3.5 mSv y -1 . The purpose of this review was to provide an independent evaluation and review of this estimate. One of the first observations was that, because site-specific dose rate measurements for the Amargosa Valley ''were not available'', the dose rates for various sources of natural background in that area, used by the USEPA in its assessment, were based on modifications of the average values for the State of Nevada. A second observation was that the conversion factor applied in estimating the dose rates due to exposures to indoor radon and its decay products was a factor of 2 higher than the currently accepted value. Further review revealed that site-specific data for many natural background sources in the Amargosa Valley were available. One particularly important observation was that about 91% of the residents of that area live in mobile homes which, due to their construction and design, have indoor radon concentrations comparable to, or less than, those outdoors. For that reason, alone, the USEPA estimate of the average dose rate for residents of the Amargosa Valley, due to indoor radon, was not valid. For purposes

Silver nanoparticles as matrix for laser desorption/ionization mass spectrometry of peptides

International Nuclear Information System (INIS)

Hua Lin; Chen Jianrong; Ge Liya; Tan, Swee Ngin

2007-01-01

Silver nanoparticle synthesized from chemical reduction has been successfully utilized as a matrix in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) of peptides. Acting as a substrate to adsorb analytes, as well as a transmission medium for UV laser, silver nanoparticle was found to assist in the desorption/ionization of peptides with little or no induced fragmentation. The size of the nanoparticle was typically in the range of 160 ± 20 nm. One of the key advantages of silver nanoparticle for peptides analysis is its simple step for on-probe sample preparation. In addition, it also minimizes the interferences of sodium dodecyl sulfate (SDS) surfactant background signal, resulting in cleaner mass spectra and more sensitive signal, when compared to α-cyano-4-hydroxycinnamic acid (CCA) matrix

Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

Science.gov (United States)

Madau, Piero; Fragos, Tassos

2017-05-01

We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior to and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z ≲ 4. Together with an updated empirical determination of the cosmic history of star formation, recent modeling of the stellar mass-metallicity relation, and a scheme for absorption by the IGM that accounts for the presence of ionized H II bubbles during the epoch of reionization, our detailed calculations provide refined predictions of the X-ray volume emissivity and filtered radiation background from “normal” galaxies at z ≳ 6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. Because of the energy dependence of photoabsorption, soft X-ray photons are produced by local sources, while more energetic radiation arrives unattenuated from larger cosmological volumes. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct He I photoionizations are the main source of IGM heating, and the temperature of the largely neutral medium in between H II cavities increases above the temperature of the cosmic microwave background (CMB) only at z ≲ 10, when the volume filling factor of H II bubbles is already ≳0.1. Therefore, in this scenario, it is only at relatively late epochs that neutral intergalactic hydrogen

Radiation Backgrounds at Cosmic Dawn: X-Rays from Compact Binaries

Energy Technology Data Exchange (ETDEWEB)

Madau, Piero [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Fragos, Tassos [Geneva Observatory, University of Geneva, Chemin des Maillettes 51, 1290 Sauverny (Switzerland)

2017-05-01

We compute the expected X-ray diffuse background and radiative feedback on the intergalactic medium (IGM) from X-ray binaries prior to and during the epoch of reionization. The cosmic evolution of compact binaries is followed using a population synthesis technique that treats separately neutron stars and black hole binaries in different spectral states and is calibrated to reproduce the observed X-ray properties of galaxies at z ≲ 4. Together with an updated empirical determination of the cosmic history of star formation, recent modeling of the stellar mass–metallicity relation, and a scheme for absorption by the IGM that accounts for the presence of ionized H ii bubbles during the epoch of reionization, our detailed calculations provide refined predictions of the X-ray volume emissivity and filtered radiation background from “normal” galaxies at z ≳ 6. Radiative transfer effects modulate the background spectrum, which shows a characteristic peak between 1 and 2 keV. Because of the energy dependence of photoabsorption, soft X-ray photons are produced by local sources, while more energetic radiation arrives unattenuated from larger cosmological volumes. While the filtering of X-ray radiation through the IGM slightly increases the mean excess energy per photoionization, it also weakens the radiation intensity below 1 keV, lowering the mean photoionization and heating rates. Numerical integration of the rate and energy equations shows that the contribution of X-ray binaries to the ionization of the bulk IGM is negligible, with the electron fraction never exceeding 1%. Direct He i photoionizations are the main source of IGM heating, and the temperature of the largely neutral medium in between H ii cavities increases above the temperature of the cosmic microwave background (CMB) only at z ≲ 10, when the volume filling factor of H ii bubbles is already ≳0.1. Therefore, in this scenario, it is only at relatively late epochs that neutral intergalactic

The health effects of low-dose ionizing radiation

International Nuclear Information System (INIS)

Dixit, A.N.; Dixit, Nishant

2012-01-01

It has been established by various researches, that high doses of ionizing radiation are harmful to health. There is substantial controversy regarding the effects of low doses of ionizing radiation despite the large amount of work carried out (both laboratory and epidemiological). Exposure to high levels of radiation can cause radiation injury, and these injuries can be relatively severe with sufficiently high radiation doses. Prolonged exposure to low levels of radiation may lead to cancer, although the nature of our response to very low radiation levels is not well known at this time. Many of our radiation safety regulations and procedures are designed to protect the health of those exposed to radiation occupationally or as members of the public. According to the linear no-threshold (LNT) hypothesis, any amount, however small, of radiation is potentially harmful, even down to zero levels. The threshold hypothesis, on the other hand, emphasizes that below a certain threshold level of radiation exposure, any deleterious effects are absent. At the same time, there are strong arguments, both experimental and epidemiological, which support the radiation hormesis (beneficial effects of low-level ionizing radiation). These effects cannot be anticipated by extrapolating from harmful effects noted at high doses. Evidence indicates an inverse relationship between chronic low-dose radiation levels and cancer incidence and/or mortality rates. Examples are drawn from: 1) state surveys for more than 200 million people in the United States; 2) state cancer hospitals for 200 million people in India; 3) 10,000 residents of Taipei who lived in cobalt-60 contaminated homes; 4) high-radiation areas of Ramsar, Iran; 5) 12 million person-years of exposed and carefully selected control nuclear workers; 6) almost 300,000 radon measurements of homes in the United States; and 7) non-smokers in high-radon areas of early Saxony, Germany. This evidence conforms to the hypothesis that

Long term bleaching of optical glasses darkened by Co60 ionizing radiation

International Nuclear Information System (INIS)

Wirtenson, G.R.; White, R.H.

1997-01-01

Typical camera designs include optical glass elements that may be affected by the ionizing radiation present in the natural space environment. Ordinary optical glasses darken at low (10(to the 3rd power) rad) dose levels when exposed to ionizing radiation. This darkening decreases the sensitivity of optical sensors. Optical glass flats of FK 51, LaK 0, PK 51A, and ZK Ny were exposed to a 10.6 krad dose of ionizing radiation. Spectrophotometer traces determined the transmittance of the samples as a function of wavelength in the range 350 to 850 nm before and at various time intervals after the irradiation. These measured values were then use to evaluate the rate of recovery or ''bleaching'' of the exposed samples. To prevent accelerated bleaching, the samples were kept at room temperature and away from light, except during measurement. Tables of the measured data and plots of the transmissivity vs. wavelength at various times after irradiation are presented

Cumulative neutrino background from quasar-driven outflows

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiawei; Loeb, Abraham, E-mail: xiawei.wang@cfa.harvard.edu, E-mail: aloeb@cfa.harvard.edu [Department of Astronomy, Harvard University, 60 Garden Street, Cambridge, MA 02138 (United States)

2016-12-01

Quasar-driven outflows naturally account for the missing component of the extragalactic γ-ray background through neutral pion production in interactions between protons accelerated by the forward outflow shock and interstellar protons. We study the simultaneous neutrino emission by the same protons. We adopt outflow parameters that best fit the extragalactic γ-ray background data and derive a cumulative neutrino background of ∼ 10{sup −7} GeV cm{sup −2} s{sup −1} sr{sup −1} at neutrino energies E {sub ν} ∼> 10 TeV, which naturally explains the most recent IceCube data without tuning any free parameters. The link between the γ-ray and neutrino emission from quasar outflows can be used to constrain the high-energy physics of strong shocks at cosmological distances.

Evaluation of the natural background radiation in City Sopron

International Nuclear Information System (INIS)

Spaits, T.; Divos, F.; Kavasi, N.; Boka, Z.

2006-01-01

In the Postgraduate School of the Faculty of Forestry of the University of West Hungary a project with the topic Research of natural radioactive isotopes in our built and natural environs is being run. Preparing this map is an organic part of this PhD research. The measurements are being made in Sopron city and in its next surroundings, trying to estimate, which dose of radiation a citizen of Sopron is exposed, according to his age and lifestyle. The measurements completely cover the built-up area of Sopron, moreover they exceed the confines, so thus they provide information about the natural areas in the vicinity of the city. In figures, the detection carried out in an area of 24 square kilometres, working with a grid mesh of 200 metres. A sodium-iodide detector was used. We have faced several anomalies while mapping. These are the following: On Main Square (Foter), Ursulin Square (Orsolya ter), Paulites Square (Palosok tere, where a higher dose can be measured, due to granite cobbles, used to cover the pavements of the squares and streets. This was confirmed by the gamma spectrometric examination of the granite stones. In these areas, a triple of the mean dose-rate of 70-90 n Sv/h in Sopron was detected. The highest values of 400 n Sv/h were detected in the cinder-covered car-park of the paint store in Koszegi Street. The total gamma activity concentration of the cinder used in the car-park was nearly 2000 Bq/kg. A triple to a quadruple of the natural level was detected in the vicinity of the chimney of the former thermal power plant and the brick factory. The detection was carried out in four directions with raising range starting by the chimneys, which has spectacularly shown, that the sedimentation of the aerosols can be tracked is a function of distance. The measurements have also shown, that there is a significant difference between dose-levels of the natural areas beyond the eastern and western edge of the city, which can be explained with the different

Technical sheets of ionizing radiations. 2. Non-ionizing radiations

International Nuclear Information System (INIS)

Anon.

1975-01-01

The biological effects of different non-ionizing radiations are studied: ultra-violet radiation, visible radiation, infrared radiation, micrometric waves, ultrasonics. In spite of their apparent diversity these radiations are similar in their physico-chemical effects, but in view of their widely varying production methods and types of application each type is considered separately. It is pointed out that no organization resembling the CIPR exists in the field of non-ionizing radiations, the result being a great disparity amongst the different legislations in force [fr

Detection of WIMPs in the Edelweiss experiment. Study of the radioactive background noise and measurements with bolometers; Recherche des wimp's du halo galactique dans l'experience edelweiss: etude du bas bruit radioactif et mesures a l'aide de bolometres a double detection ionisation/chaleur

Energy Technology Data Exchange (ETDEWEB)

Miramonti, L. [CEA/Saclay, Dept. d' Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l' Instrumentation Associee (DAPNIA), 91 - Gif-sur-Yvette (France)]|[Paris-11 Univ., 91 - Orsay (France)

1999-11-01

This thesis is dedicated to the detection of black matter in the form of WIMPs (weakly interacting massive particle). The characteristics of the interaction of WIMPs with matter are recalled. The very low number of expected events (<1 event/day.Kg) implies a radioactive background noise as weak as possible, furthermore the exponential decrease of the interacting rate with increasing energy calls for detectors with very low thresholds. Bolometers present advantages in WIMPs detection: i) very good resolution and very low thresholds, ii) very broad range of materials that can be used as absorber, the only requirements are: a crystal structure, to be a diamagnetic isolator and to have a convenient Debye temperature, iii) the possibility of detecting ionizing or non-ionizing particles, iv) the possibility of identifying the incident particle by measuring both temperature and another parameter such as ionization or scintillation, and v) the possibility of localizing the interaction inside the absorber by detecting ballistic phonons. The problematic of radioactive background noise is presented and the answers to the different sources (cosmic radiation,natural and artificial radioactivity) generating the background noise are examined. The materials used in the building of the detector and cryostat must be carefully chosen, they should be as little radioactive as possible. The test benches used to select materials for the Edelweiss experiment are described. The first measurements concerning the detectors Ge-4 and Ge-7 are presented. (A.C.)

Simple method for identifying doubly ionized uranium (U III) produced in a hollow-cathode discharge

International Nuclear Information System (INIS)

Piyakis, K.N.; Gagne, J.M.

1988-01-01

We have studied by emission spectroscopy the spectral properties of doubly ionized uranium, produced in a vapor generator of hollow-cathode design, as a function of the nature of a pure fill gas (helium, neon, argon, krypton, xenon) and its pressure. The spectral intensity is found to increase with increasing ionization potential of the discharge buffer gas, except in the case of helium. Based on our preliminary results, a simple and practical method for the positive identification of the complex U III spectrum is suggested

Effects of ionizing radiation; Effecten van ioniserende straling

Energy Technology Data Exchange (ETDEWEB)

Loos, M.; Hardeman, F.; Holmstock, L.; Hurtgen, C.; Mahieu, L.; Sohier, A.; Vandecasteele, C.; Vanhavere, F.; Vanmaercke, H.; Zeevaert, T

1998-12-01

Starting with a brief introduction to radiation protection, the report gives an overview of exposure to ionising radiation in Belgium due to activities in relation to the nuclear fuel cycle, processing and disposal of radioactive waste and other artificial or natural sources. Where appropriate, the Belgian situation discussed from an international perspective. The radiological impact of reprocessing and non-reprocessing are compared. The biological effects of ionizing radiation, epidemiological studies as well as surveillance programmes on the Belgian territory are reported on.

French population's exposure to ionizing radiations

International Nuclear Information System (INIS)

2016-01-01

This report deals with the exposure of the French population to ionizing radiation. The exposures taken into account are related to cosmic and telluric radiations, to radon, to ingestion of natural radionuclides, to medical imaging and to industrial and military sources. Additionally to the mean effective dose, considered as the macroscopic indicator of the population exposure, the variations of the effective dose for each source of exposure are also presented. Then, the variation of the total effective dose is presented. (authors)

Mapping the exposure of the Brazilian population to natural background radiation - cosmic radiation

Energy Technology Data Exchange (ETDEWEB)

Rochedo, Elaine R.R., E-mail: elaine@ird.gov.br [Instituto de Radioprotecao e Dosimetria (lRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Salles, Krause C.S.; Prado, Nadya M.C., E-mail: krausesalles@yahoo.com.br, E-mail: nadya@ime.ib.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil)

2013-07-01

The main objective of this work is to statically and graphically describe the exposure of the Brazilian population to natural background radiation. in this stage, doses due to cosmic rays is being assessed based on sea level dose rates, corrected by latitude and altitude, according to the model recommended by UNSCEAR. In this work, the doses were estimated for ali Brazilian municipalities with more than 100.000 inhabitants. The 253 municipalities selected for this study include about 52% of the Brazilian population. Average dose rate was estimated to be about 50 n Sv/h with a variation coefficient of 31%. The estimated doses have shown a strong influence of altitude on dose rates, with a correlation coefficient of 0,998 for ao exponential fit. This result confirms previous studies that show a large effect of the altitude 00 exposure from cosmic radiation. Considering the same occupation and shielding conditions used by UNSCEAR as global averages, average annual dose was estimated to be 0,37 (0,24 - 0,76) mSv/y, very close to UNSCEAR worldwide average of 0,38 (0,3 - 1,0) mSv/y. (author)

Mapping the exposure of the Brazilian population to natural background radiation - cosmic radiation

International Nuclear Information System (INIS)

Rochedo, Elaine R.R.; Salles, Krause C.S.; Prado, Nadya M.C.

2013-01-01

The main objective of this work is to statically and graphically describe the exposure of the Brazilian population to natural background radiation. in this stage, doses due to cosmic rays is being assessed based on sea level dose rates, corrected by latitude and altitude, according to the model recommended by UNSCEAR. In this work, the doses were estimated for ali Brazilian municipalities with more than 100.000 inhabitants. The 253 municipalities selected for this study include about 52% of the Brazilian population. Average dose rate was estimated to be about 50 n Sv/h with a variation coefficient of 31%. The estimated doses have shown a strong influence of altitude on dose rates, with a correlation coefficient of 0,998 for ao exponential fit. This result confirms previous studies that show a large effect of the altitude 00 exposure from cosmic radiation. Considering the same occupation and shielding conditions used by UNSCEAR as global averages, average annual dose was estimated to be 0,37 (0,24 - 0,76) mSv/y, very close to UNSCEAR worldwide average of 0,38 (0,3 - 1,0) mSv/y. (author)

The ionization mechanisms in direct and dopant-assisted atmospheric pressure photoionization and atmospheric pressure laser ionization.

Science.gov (United States)

Kauppila, Tiina J; Kersten, Hendrik; Benter, Thorsten

2014-11-01

A novel, gas-tight API interface for gas chromatography-mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77](+) in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.

Mass spectrometry of solid samples in open air using combined laser ionization and ambient metastable ionization

International Nuclear Information System (INIS)

He, X.N.; Xie, Z.Q.; Gao, Y.; Hu, W.; Guo, L.B.; Jiang, L.; Lu, Y.F.

2012-01-01

Mass spectrometry of solid samples in open air was carried out using combined laser ionization and metastable ionization time-of-flight mass spectrometry (LI-MI-TOFMS) in ambient environment for qualitative and semiquantitative (relative analyte information, not absolute information) analysis. Ambient metastable ionization using a direct analysis in realtime (DART) ion source was combined with laser ionization time-of-flight mass spectrometry (LI-TOFMS) to study the effects of combining metastable and laser ionization. A series of metallic samples from the National Institute of Standards and Technology (NIST 494, 495, 498, 499, and 500) and a pure carbon target were characterized using LI-TOFMS in open air. LI-MI-TOFMS was found to be superior to laser-induced breakdown spectroscopy (LIBS). Laser pulse energies between 10 and 200 mJ at the second harmonic (532 nm) of an Nd:YAG laser were applied in the experiment to obtain a high degree of ionization in plasmas. Higher laser pulse energy improves signal intensities of trace elements (such as Fe, Cr, Mn, Ni, Ca, Al, and Ag). Data were analyzed by numerically calculating relative sensitivity coefficients (RSCs) and limit of detections (LODs) from mass spectrometry (MS) and LIBS spectra. Different parameters, such as boiling point, ionization potential, RSC, LOD, and atomic weight, were shown to analyze the ionization and MS detection processes in open air.

World high background natural radiation areas: Need to protect public from radiation exposure

International Nuclear Information System (INIS)

Sohrabi, Mehdi

2013-01-01

Highlights of findings on radiological measurements, radiobiological and epidemiological studies in some main world high background natural radiation (HBNR) areas such as in Brazil, China, India and Iran are presented and discussed with special regard to remediation of radiation exposure of inhabitants in such areas. The current radiation protection philosophy and recommendations applied to workers and public from operation of radiation and nuclear applications are based on the linear non-threshold (LNT) model. The inhabitants of HBNR and radon prone areas receive relatively high radiation doses. Therefore, according to the LNT concept, the inhabitants in HBNR areas and in particular those in Ramsar are considered at risk and their exposure should be regulated. The HBNR areas in the world have different conditions in terms of dose and population. In particular, the inhabitants in HBNR areas of Ramsar receive very high internal and external exposures. This author believes that the public in such areas should be protected and proposes a plan to remedy high exposure of the inhabitants of the HBNR areas of Ramsar, while maintaining these areas as they stand to establish a national environmental radioactivity park which can be provisionally called “Ramsar Research Natural Radioactivity Park” (RRNRP). The major HBNR areas, the public exposure and the need to remedy exposures of inhabitants are reviewed and discussed. - Highlights: ► Highlights of findings on studies in HBNR areas are reviewed and discussed. ► The need to protect HBNR area inhabitants and remedy public exposure is emphasized. ► A collective approach is proposed to remedy exposure of Ramsar HBNR area inhabitants. ► Relocation of HBNR area inhabitants and establishing a park at the location is proposed. ► The advantages and disadvantages of the methods are discussed and recommendations are made

Molecular mechanisms of drug resistance in natural Leishmania populations vary with genetic background.

Directory of Open Access Journals (Sweden)

Saskia Decuypere

Full Text Available The evolution of drug-resistance in pathogens is a major global health threat. Elucidating the molecular basis of pathogen drug-resistance has been the focus of many studies but rarely is it known whether a drug-resistance mechanism identified is universal for the studied pathogen; it has seldom been clarified whether drug-resistance mechanisms vary with the pathogen's genotype. Nevertheless this is of critical importance in gaining an understanding of the complexity of this global threat and in underpinning epidemiological surveillance of pathogen drug resistance in the field. This study aimed to assess the molecular and phenotypic heterogeneity that emerges in natural parasite populations under drug treatment pressure. We studied lines of the protozoan parasite Leishmania (L. donovani with differential susceptibility to antimonial drugs; the lines being derived from clinical isolates belonging to two distinct genetic populations that circulate in the leishmaniasis endemic region of Nepal. Parasite pathways known to be affected by antimonial drugs were characterised on five experimental levels in the lines of the two populations. Characterisation of DNA sequence, gene expression, protein expression and thiol levels revealed a number of molecular features that mark antimonial-resistant parasites in only one of the two populations studied. A final series of in vitro stress phenotyping experiments confirmed this heterogeneity amongst drug-resistant parasites from the two populations. These data provide evidence that the molecular changes associated with antimonial-resistance in natural Leishmania populations depend on the genetic background of the Leishmania population, which has resulted in a divergent set of resistance markers in the Leishmania populations. This heterogeneity of parasite adaptations provides severe challenges for the control of drug resistance in the field and the design of molecular surveillance tools for widespread

Self-probing spectroscopy of XUV photo-ionization dynamics in atoms subjected to a strong-field environment.

Science.gov (United States)

Azoury, Doron; Krüger, Michael; Orenstein, Gal; Larsson, Henrik R; Bauch, Sebastian; Bruner, Barry D; Dudovich, Nirit

2017-11-13

Single-photon ionization is one of the most fundamental light matter interactions in nature, serving as a universal probe of the quantum state of matter. By probing the emitted electron, one can decode the full dynamics of the interaction. When photo-ionization is evolving in the presence of a strong laser field, the fundamental properties of the mechanism can be signicantly altered. Here we demonstrate how the liberated electron can perform a self-probing measurement of such interaction with attosecond precision. Extreme ultraviolet attosecond pulses initiate an electron wavepacket by photo-ionization, a strong infrared field controls its motion, and finally electron-ion collision maps it into re-emission of attosecond radiation bursts. Our measurements resolve the internal clock provided by the self-probing mechanism, obtaining a direct insight into the build-up of photo-ionization in the presence of the strong laser field.

MAGNETIC RECONNECTION IN NON-EQUILIBRIUM IONIZATION PLASMA

International Nuclear Information System (INIS)

Imada, S.; Shimizu, T.; Murakami, I.; Watanabe, T.; Hara, H.

2011-01-01

We have studied the effect of time-dependent ionization and the recombination processes on magnetic reconnection in the solar corona. Petschek-type steady reconnection, in which the magnetic energy is mainly converted at the slow-mode shocks, was assumed. We carried out the time-dependent ionization calculation in the magnetic reconnection structure. We only calculated the transient ionization of iron; the other species were assumed to be in ionization equilibrium. The intensity of line emissions at specific wavelengths was also calculated for comparison with Hinode or other observations in future. We found the following: (1) iron is mostly in non-equilibrium ionization in the reconnection region; (2) the intensity of line emission estimated by the time-dependent ionization calculation is significantly different from that determined from the ionization equilibrium assumption; (3) the effect of time-dependent ionization is sensitive to the electron density in the case where the electron density is less than 10 10 cm –3 ; (4) the effect of thermal conduction lessens the time-dependent ionization effect; and (5) the effect of radiative cooling is negligibly small even if we take into account time-dependent ionization.

Aerosol quantification with the Aerodyne Aerosol Mass Spectrometer: detection limits and ionizer background effects

Directory of Open Access Journals (Sweden)

S. Borrmann

2009-02-01

Full Text Available Systematic laboratory experiments were performed to investigate quantification of various species with two versions of the Aerodyne Aerosol Mass Spectrometer, a Quadrupole Aerosol Mass Spectrometer (Q-AMS and a compact Time-of-Flight Aerosol Mass Spectrometer (c-ToF-AMS. Here we present a new method to continuously determine the detection limits of the AMS analyzers during regular measurements, yielding detection limit (DL information under various measurement conditions. Minimum detection limits range from 0.03 μg m⁻³ (nitrate, sulfate, and chloride up to 0.5 μg m⁻³ (organics for the Q-AMS. Those of the c-ToF-AMS are found between 0.003 μg m⁻³ (nitrate, sulfate and 0.03 μg m⁻³ (ammonium, organics. The DL values found for the c-ToF-AMS were ~10 times lower than those of the Q-AMS, mainly due to differences in ion duty cycle. Effects causing an increase of the detection limits include long-term instrument contamination, measurement of high aerosol mass concentrations and short-term instrument history. The self-cleaning processes which reduce the instrument background after measurement of large aerosol concentrations as well as the influences of increased instrument background on mass concentration measurements are discussed. Finally, improvement of detection limits by extension of averaging time intervals, selected or reduced ion monitoring, and variation of particle-to-background measurement ratio are investigated.

Ionization Processes in the Atmosphere of Titan (Research Note). III. Ionization by High-Z Nuclei Cosmic Rays

Science.gov (United States)

Gronoff, G.; Mertens, C.; Lilensten, J.; Desorgher, L.; Fluckiger, E.; Velinov, P.

2011-01-01

Context. The Cassini-Huygens mission has revealed the importance of particle precipitation in the atmosphere of Titan thanks to in-situ measurements. These ionizing particles (electrons, protons, and cosmic rays) have a strong impact on the chemistry, hence must be modeled. Aims. We revisit our computation of ionization in the atmosphere of Titan by cosmic rays. The high-energy high-mass ions are taken into account to improve the precision of the calculation of the ion production profile. Methods. The Badhwahr and O Neill model for cosmic ray spectrum was adapted for the Titan model. We used the TransTitan model coupled with the Planetocosmics model to compute the ion production by cosmic rays. We compared the results with the NAIRAS/HZETRN ionization model used for the first time for a body that differs from the Earth. Results. The cosmic ray ionization is computed for five groups of cosmic rays, depending on their charge and mass: protons, alpha, Z = 8 (oxygen), Z = 14 (silicon), and Z = 26 (iron) nucleus. Protons and alpha particles ionize mainly at 65 km altitude, while the higher mass nucleons ionize at higher altitudes. Nevertheless, the ionization at higher altitude is insufficient to obscure the impact of Saturn s magnetosphere protons at a 500 km altitude. The ionization rate at the peak (altitude: 65 km, for all the different conditions) lies between 30 and 40/cu cm/s. Conclusions. These new computations show for the first time the importance of high Z cosmic rays on the ionization of the Titan atmosphere. The updated full ionization profile shape does not differ significantly from that found in our previous calculations (Paper I: Gronoff et al. 2009, 506, 955) but undergoes a strong increase in intensity below an altitude of 400 km, especially between 200 and 400 km altitude where alpha and heavier particles (in the cosmic ray spectrum) are responsible for 40% of the ionization. The comparison of several models of ionization and cosmic ray spectra (in

The Ionizing Radiation Environment on the International Space Station: Performance vs. Expectations for Avionics and Materials

Science.gov (United States)

Koontz, Steven L.; Boeder, Paul A.; Pankop, Courtney; Reddell, Brandon

2005-01-01

The role of structural shielding mass in the design, verification, and in-flight performance of International Space Station (ISS), in both the natural and induced orbital ionizing radiation (IR) environments, is reported.

Foundations of ionizing radiation dosimetry

International Nuclear Information System (INIS)

Denisenko, O.N.; Pereslegin, I.A.

1985-01-01

Foundations of dosimetry in application to radiotherapy are presented. General characteristics of ionizing radiations and main characteristics of ionizing radiation sources, mostly used in radiotherapy, are given. Values and units for measuring ionizing radiation (activity of a radioactive substance, absorbed dose, exposure dose, integral dose and dose equivalent are considered. Different methods and instruments for ionizing radiation dosimetry are discussed. The attention is paid to the foundations of clinical dosimetry (representation of anatomo-topographic information, choice of radiation conditions, realization of radiation methods, corrections for a configuration and inhomogeneity of a patient's body, account of biological factors of radiation effects, instruments of dose field formation, control of irradiation procedure chosen)

Enhanced ionized impurity scattering in nanowires

Science.gov (United States)

Oh, Jung Hyun; Lee, Seok-Hee; Shin, Mincheol

2013-06-01

The electronic resistivity in silicon nanowires is investigated by taking into account scattering as well as the donor deactivation from the dielectric mismatch. The effects of poorly screened dopant atoms from the dielectric mismatch and variable carrier density in nanowires are found to play a crucial role in determining the nanowire resistivity. Using Green's function method within the self-consistent Born approximation, it is shown that donor deactivation and ionized impurity scattering combined with the charged interface traps successfully to explain the increase in the resistivity of Si nanowires while reducing the radius, measured by Björk et al. [Nature Nanotech. 4, 103 (2009)].

Analysis of laser ablation: Contribution of ionization energy to the plasma and shock wave properties

International Nuclear Information System (INIS)

Wen, S.-B.; Mao Xianglei; Greif, Ralph; Russo, Richard E.

2007-01-01

By fitting simulation results with experimentally measured trajectories of the shock wave and the vapor/background gas contact surface, we found that inclusion of ionization energy in the analysis leads to a change in the evolution of the pressure, mass density, electron number density, and temperature of the vapor plume. The contribution of ionization energy to both the plasma and shock wave has been neglected in most studies of laser ablation. Compared to previous simulations, the densities, pressures, and temperatures are lower shortly after the laser pulse ( 50 ns). The predicted laser energy conversion ratio also showed about a 20% increase (from 35% to 45%) when the ionization energy is considered. The changes in the evolution of the physical quantities result from the retention of the ionization energy in the vapor plume, which is then gradually transformed to kinetic and thermal energies. When ionization energy is included in the simulation, the vapor plume attains higher expansion speeds and temperatures for a longer time after the laser pulse. The better determination of the temperature history of the vapor plume not only improves the understanding of the expansion process of the laser induced vapor plume but also is important for chemical analysis. The accurate temperature history provides supplementary information which enhances the accuracy of chemical analysis based on spectral emission measurements (e.g., laser induced breakdown spectroscopy)

Simultaneous atomization and ionization of large organic molecules using femtosecond laser ablation

International Nuclear Information System (INIS)

Kurata-Nishimura, Mizuki; Tokanai, Fuyuki; Matsuo, Yukari; Kobayashi, Tohru; Kawai, Jun; Kumagai, Hiroshi; Midorikawa, Katsumi; Tanihata, Isao; Hayashizaki, Yoshihide

2002-01-01

We have experimentally demonstrated femtosecond laser ablation for simultaneous atomization and ionization (fs-SAI) of organic molecules on solid substrates. We find most of the constituent atoms of organic molecules are atomized and ionized non-resonantly by femtosecond laser ablation. This observation is in contrast with that for the photoionization of cyclic aromatic hydrocarbons by femtosecond laser in the gas phase where little fragmentation has been observed. Crucial contribution of ablation plasma of solid sample to fs-SAI process is suggested. The ratio of natural abundance of stable isotopes contained in sample molecules is well reproduced, which confirms fs-SAI can be applied to the quantitative chemical analysis of isotope-labeled large organic molecules

Frustrated incomplete donor ionization in ultra-low resistivity germanium films

International Nuclear Information System (INIS)

Xu, Chi; Menéndez, J.; Senaratne, C. L.; Kouvetakis, J.

2014-01-01

The relationship between carrier concentration and donor atomic concentration has been determined in n-type Ge films doped with P. The samples were carefully engineered to minimize non-active dopant incorporation by using specially designed P(SiH 3 ) 3 and P(GeH 3 ) 3 hydride precursors. The in situ nature of the doping and the growth at low temperatures, facilitated by the Ge 3 H 8 and Ge 4 H 10 Ge sources, promote the creation of ultra-low resistivity films with flat doping profiles that help reduce the errors in the concentration measurements. The results show that Ge deviates strongly from the incomplete ionization expected when the donor atomic concentration exceeds N d  = 10 17  cm −3 , at which the energy separation between the donor and Fermi levels ceases to be much larger than the thermal energy. Instead, essentially full ionization is seen even at the highest doping levels beyond the solubility limit of P in Ge. The results can be explained using a model developed for silicon by Altermatt and coworkers, provided the relevant model parameter is properly scaled. The findings confirm that donor solubility and/or defect formation, not incomplete ionization, are the major factors limiting the achievement of very high carrier concentrations in n-type Ge. The commercially viable chemistry approach applied here enables fabrication of supersaturated and fully ionized prototypes with potential for broad applications in group-IV semiconductor technologies

Ionization of xenon by electrons: Partial cross sections for single, double, and triple ionization

International Nuclear Information System (INIS)

Mathur, D.; Badrinathan, C.

1987-01-01

High-sensitivity measurements of relative partial cross sections for single, double, and triple ionization of Xe by electron impact have been carried out in the energy region from threshold to 100 eV using a crossed-beam apparatus incorporating a quadrupole mass spectrometer. The weighted sum of the relative partial cross sections at 50 eV are normalized to the total ionization cross section of Rapp and Englander-Golden to yield absolute cross-section functions. Shapes of the partial cross sections for single and double ionization are difficult to account for within a single-particle picture. Comparison of the Xe + data with 4d partial photoionization cross-section measurements indicates the important role played by many-body effects in describing electron-impact ionization of high-Z atoms

Modeling and simulation of two-step resonance ionization processes using CW and pulsed lasers

CERN Document Server

de Groote, Ruben; Flanagan, Kieran

This thesis derives and discusses equations that describe the evolution of atomic systems subjected to two monochromatic and coherent radiation fields and treats both continuous and temporally pulsed irradiation. This theoretical description is de- veloped mainly to understand the influence of the photon field intensities on experimental ionization spectra. The primary ap- plication of this theoretical framework is on methods that rely on resonant laser excitation and non-resonant laser ionization to extract information on the hyperfine structure of atomic systems. In particular, qualitative and quantitative discussions on the laser-related changes in hyperfine splitting extracted from ion- ization spectra are presented. Also, a method for increasing the resolution of resonance ionization techniques (potentially up un- til the natural linewidth of the electronic transitions) is discussed and theoretically justified. Both topics are illustrated with exper- imental data.

Study on ionizing radiation effects of bipolar transistor with BPSG films

International Nuclear Information System (INIS)

Lu Man; Zhang Xiaoling; Xie Xuesong; Sun Jiangchao; Wang Pengpeng; Lu Changzhi; Zhang Yanxiu

2013-01-01

Background: Because of the damage induced by ionizing radiation, bipolar transistors in integrated voltage regulator could induce the current gain degradation and increase leakage current. This will bring serious problems to electronic system. Purpose: In order to ensure the reliability of the device work in the radiation environments, the device irradiation reinforcement technology is used. Methods: The characteristics of 60 Co γ irradiation and annealing at different temperatures in bipolar transistors and voltage regulators (JW117) with different passive films for SiO 2 +BPSG+SiO 2 and SiO 2 +SiN have been investigated. Results: The devices with BPSG film enhanced radiation tolerance significantly. Because BPSG films have better absorption for Na + in SiO 2 layer, the surface recombination rate of base region in a bipolar transistor and the excess base current have been reduced. It may be the main reason for BJT with BPSG film having a good radiation hardness. And annealing experiments at different temperatures after irradiation ensure the reliability of the devices with BPSG films. Conclusions: A method of improving the ionizing irradiation hardness of bipolar transistors is proposed. As well as the linear integrated circuits which containing bipolar transistors, an experimental basis for the anti-ionizing radiation effects of bipolar transistors is provided. (authors)

Ionization particle detector

International Nuclear Information System (INIS)

Ried, L.

1982-01-01

A new device is claimed for detecting particles in a gas. The invention comprises a low cost, easy to assemble, and highly accurate particle detector using a single ionization chamber to contain a reference region and a sensing region. The chamber is designed with the radioactive source near one electrode and the second electrode located at a distance less than the distance of maximum ionization from the radioactive source

Ionization detection system for aerosols

International Nuclear Information System (INIS)

Jacobs, M.E.

1977-01-01

This invention relates to an improved smoke-detection system of the ionization-chamber type. In the preferred embodiment, the system utilizes a conventional detector head comprising a measuring ionization chamber, a reference ionization chamber, and a normally non-conductive gas triode for discharging when a threshold concentration of airborne particulates is present in the measuring chamber. The improved system utilizes a measuring ionization chamber which is modified to minimize false alarms and reductions in sensitivity resulting from changes in ambient temperature. In the preferred form of the modification, an annular radiation shield is mounted about the usual radiation source provided to effect ionization in the measuring chamber. The shield is supported by a bimetallic strip which flexes in response to changes in ambient temperature, moving the shield relative to the source so as to vary the radiative area of the source in a manner offsetting temperature-induced variations in the sensitivity of the chamber. 8 claims, 7 figures

News about ionized food identification

International Nuclear Information System (INIS)

Raffi, J.

1995-01-01

The ionizing radiations are used to clean food and increase their preservation life. If a lot of countries permits ionized products commercialization, others are opposed to it. To control the commercial exchanges, check the applied treatment aim and give to the consumers a better information, several ionized food identification methods were perfected and several are about to be recognized as european standards. 4 refs. 3 figs, 1 tab

Use of phytoceuticals from natural resource for mitigation of ionizing radiation hazard

International Nuclear Information System (INIS)

Nair, C.K.K.

2013-01-01

Free radicals and reactive oxygen species generated as a result of exposure of living systems to ionizing radiation cause a variety of damages to DNA, membranes etc. The radiation induced lesions in the cellular DNA are mainly strand breaks, damage to sugar moiety, alterations and elimination of bases, cross links of the intra and inter strand type and cross links to proteins while peroxidation of the lipids and oxidation of proteins constitute the major lesions in the membranes. The radioprotectors elicit their action by various mechanisms such as : i) by suppressing the formation of reactive species, ii) detoxification of radiation induced species, iii) target stabilization and iv) enhancing the repair and recovery processes. The radioprotective compounds are of importance in medical, industrial, environmental, military and space science applications. Radiation protection might offer a tactical advantage on the battle field in the event of a nuclear warfare. Radioprotectors might reduce the cancer risk to populations exposed to radiations directly or indirectly through industrial and military applications. They are required to reduce the normal tissue injury during radiotherapy of cancer. The recent incidences of terrorism have increased the fear of nuclear terrorism and the risk associated with the possible radioactive contamination with dirty bombs. This has created a global awareness for emergency preparedness and need for finding radioprotectors for human application and recent literature reveals enormous interest in this field. The earlier studies were centered around on thiols, aminothiols and their derivatives and found 'the gold standard' radioprotective drug amyfostin or ethyol or WR2127. Most of these protect cells, membranes and biomolecules such as DNA and proteins in vitro. However many of these though show promising results in laboratory studies are of limited human application due to several factors such as toxicity, difficulties in administering

Loss of ions in cavity ionization chambers

International Nuclear Information System (INIS)

Takata, N.; Tran, N.T.; Kim, E.; Marsoem, P.; Kurosawa, T.; Koyama, Y.

2005-01-01

Ion losses due to initial recombination, volume recombination, and back diffusion were each determined by measurements and calculations for different size cylindrical ionization chambers and spherical ionization chambers. By measuring signal currents from these ionization chambers irradiated with 60 Co gamma rays, two groups of ion losses were obtained. (Group 1) Ion loss due to initial recombination and diffusion, which changes proportionally to the inverse of the voltage applied to the ionization chambers; (and group 2) ion loss due to volume recombination, which changes proportionally to the inverse of the square of the applied voltage. The diffusion loss was obtained separately by computing electric field distributions in the ionization chambers. It was found that diffusion loss is larger than initial recombination loss for the cylindrical ionization chambers and vise versa for the spherical ionization chambers

Background radiation map of Thailand

International Nuclear Information System (INIS)

Angsuwathana, P.; Chotikanatis, P.

1997-01-01

The radioelement concentration in the natural environment as well as the radiation exposure to man in day-to-day life is now the most interesting topic. The natural radiation is frequently referred as a standard for comparing additional sources of man-made radiation such as atomic weapon fallout, nuclear power generation, radioactive waste disposal, etc. The Department of Mineral Resources commenced a five-year project of nationwide airborne geophysical survey by awarding to Kenting Earth Sciences International Limited in 1984. The original purpose of survey was to support mineral exploration and geological mapping. Subsequently, the data quantity has been proved to be suitable for natural radiation information. In 1993 the Department of Mineral Resources, with the assistance of IAEA, published a Background Radiation Map of Thailand at the scale of 1:1,000,000 from the existing airborne radiometric digital data. The production of Background Radiation Map of Thailand is the result of data compilation and correction procedure developed over the Canadian Shield. This end product will be used as a base map in environmental application not only for Thailand but also Southeast Asia region. (author)

Cytogenetic studies on newborns from high level natural background radiation areas of Kerala coast, South India

International Nuclear Information System (INIS)

Cherian, V.D.; Kurien, C.J.; Das, Birajalaxmi

1997-01-01

The human population residing in the monazite bearing high level natural background radiation (HLNBR) areas of Kerala, along the South-West coast of India provides unique opportunities of assessing directly in man, the health effects of chronic low-level radiation exposure. The per capita dose received by this population is nearly four times the normal background radiation level. While this is the average dose, the radiation levels prevailing in these HLNBR areas are in the range of 1 to over 35 mGy per year. Chromosomal aberration studies in the lymphocytes of newborns and adults from these areas have been in progress for two decades. So far, 4156 newborn babies from HLNBR and 7321 from normal background radiation (NBR) areas have been screened for the incidence of chromosomal aberrations (dicentrics and rings). The mean frequency of dicentrics and rings did not show any significant difference between the newborns in the control and the HLNBRA population. Assessment of the frequency of micronuclei in cytochalasin-B blocked binucleated lymphocytes of 49 newborns from control areas and 131 newborns from radioactive areas also showed similar values. While an age-dependent increase in chromosome aberration frequency was observed in the adult samples from control and the study areas, the regression analysis of the data indicated a marginally higher slope for the samples from HLNBRA. Karyotype anomalies recorded so far among the newborns have not revealed any significant difference in the incidence of numerical (including Down syndrome) and structural alterations between the control and the exposed populations. A noteworthy observation, herein reported for the first time from any HLNBR area is that there is no discernible increase in the incidence of micronuclei and chromosomal aberrations in the peripheral lymphocytes of newborn babies hailing from HLNBR areas, where their ancestral generations have lived for several hundreds of years. (author)

Concept of an ionizing time-domain matter-wave interferometer

OpenAIRE

Nimmrichter, Stefan; Haslinger, Philipp; Hornberger, Klaus; Arndt, Markus

2011-01-01

We discuss the concept of an all-optical and ionizing matter-wave interferometer in the time domain. The proposed setup aims at testing the wave nature of highly massive clusters and molecules, and it will enable new precision experiments with a broad class of atoms, using the same laser system. The propagating particles are illuminated by three pulses of a standing ultraviolet laser beam, which detaches an electron via efficient single photon-absorption. Optical gratings may have periods as ...

Building Materials, Ionizing Radiation and HBIM: A Case Study from Pompei (Italy

Directory of Open Access Journals (Sweden)

Pasquale Argenziano

2018-01-01

Full Text Available This paper presents a different point of view on the conservation of the built heritage, adding ionizing radiation to the most well-known digital documentation dataset. Igneous building materials characterize most of the built heritage in the Campania region, and in a large part of southern Italy. The ionizing radiations proceeding from these materials can produce stochastic biological effects on the exposed living beings. The research team designed and tested a technical-scientific protocol to survey and analyse this natural phenomenon in association with the use of geological material for building purposes. Geographical Information Systems (GISs, City Information Modelling (CIM, and Building Information Modelling (BIM are the digital tools used to manage the construction entities and their characteristics, and then to represent the thematic data as false-colour images. The emission spectra of fair-faced or plastered materials as a fingerprint of their nature is proposed as a non-invasive method. Due to both the huge presence of historical buildings and an intense touristic flow, the main square of Pompei has been selected as a study area.

Ionizing radiation induced biological response and its public health implication

International Nuclear Information System (INIS)

Koeteles, Gy.

1994-01-01

Several sources of ionizing radiation exist in natural and artificial environment of humanity. An overview of their biological effects and the biological response of man is present. Emphasize is given to the differences caused by high and low doses. The interrelation of radiology, radiation hygiene and public health is pointed out. Especially, the physical and biological effects of radiation on cells and their responses are discussed in more detail. (R.P.)

Study on the Mediterranean coastal seaweed Ulva linza exposed to natural and stressed environmental conditions

Directory of Open Access Journals (Sweden)

Ayman Abd Elmoneim El-Gamal

2015-10-01

Full Text Available Objective: To study Ulva linza (U. linza as macro-alga exposed to different levels of ionizing radiation from the natural background of radioactivity. Methods: Samples of U. linza were collected from two different habitats at the two terminals of the rocky shore of Abu Qir Bay, Alexandria, Egypt. The western terminal at Abu Qir represented an area of normal background radiation while the eastern terminal at Rosetta represented an area of relatively high background radiation. Distinguishing between the algae grown in areas of relatively high and normal background radiation was investigated by using different indicators. Moreover, the ambient water quality was measured and the concentrations of natural radionuclides (238U, 232Th and 40K bio-accumulated in the tested macro-alga were detected. Results: The algae naturally exposed to radionuclides (238U series, 232Th series and 40K were investigated. Radiation dose rates in U. linza inhabiting in Rosetta and Abu Qir were calculated as 70.12 and 42.67 nGy/h, respectively. Chemical analysis of algal samples demonstrated that total pigment contents were 2.21 and 2.19 mg/g on a fresh weight basis for U. linza inhabiting in Rosetta and Abu Qir, respectively. Fatty acid compositions showed comparable profiles for both algal samples with saturated fatty acids as major component. The results of protein profiles confirmed slight differential expression in protein bands. Sequence-related randomly amplified polymorphic DNA provided evidence that both samples were strongly similar. By using transmission electron microscopy, no obvious ultra structural changes in the examined cells were observed. Conclusions: These experimental results demonstrate that radiation doses are not high enough to cause damage or manifest any significant variation in Ulva tissues.

Laser-induced ionization of Na vapor

International Nuclear Information System (INIS)

Wu, R.C.Y.; Judge, D.L.; Roussel, F.; Carre, B.; Breger, P.; Spiess, G.

1982-01-01

The production of Na 2 + ions by off-resonant laser excitation in the 5800-6200A region mainly results from two-photon absorption by the Na 2 molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third photon or (b) coupling to the molecular Na 2 D 1 PIμ Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al. It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na 2 + ion. From the ratio of molecular to atomic concentration in the crossed beam experiment of Polak-Dingels et al we estimate that the cross section for producing Na 2 + through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na 2 molecules

Resveratrol sensitization of DU145 prostate cancer cells to ionizing radiation is associated to ceramide increase.

Science.gov (United States)

Scarlatti, Francesca; Sala, Giusy; Ricci, Clara; Maioli, Claudio; Milani, Franco; Minella, Marco; Botturi, Marco; Ghidoni, Riccardo

2007-08-08

Radiotherapy is an established therapeutic modality for prostate cancer. Since it is well known that radiotherapy is limited due to its severe toxicity towards normal cells at high dose and minimal effect at low dose, the search for biological compounds that increase the sensitivity of tumors cells to radiation may improve the efficacy of therapy. Resveratrol, a natural antioxidant, was shown to inhibit carcinogenesis in animal models, and to block the process of tumor initiation and progression. The purpose of this study was to examine whether or not resveratrol can sensitize DU145, an androgen-independent human prostate cancer cell line, to ionizing radiation. We report here that DU145 cells are resistant to ionizing radiation-induced cell death, but pretreatment with resveratrol significantly enhances cell death. Resveratrol acts synergistically with ionizing radiation to inhibit cell survival in vitro. Resveratrol also potentiates ionizing radiation-induced ceramide accumulation, by promoting its de novo biosynthesis. This confirms ceramide as an effective mediator of the anticancer potential induced by resveratrol.

Biology of ionizing radiation effects

International Nuclear Information System (INIS)

Ferradini, C.; Pucheault, J.

1983-01-01

The present trends in biology of ionizing radiation are reviewed. The following topics are investigated: interaction of ionizing radiations with matter; the radiolysis of water and aqueous solutions; properties of the free radicals intervening in the couples O 2 /H 2 O and H 2 O/H 2 ; radiation chemistry of biological compounds; biological effects of ionizing radiations; biochemical mechanisms involving free radicals as intermediates; applications (biotechnological applications, origins of life) [fr

29 CFR 1926.53 - Ionizing radiation.

Science.gov (United States)

2010-07-01

... 29 Labor 8 2010-07-01 2010-07-01 false Ionizing radiation. 1926.53 Section 1926.53 Labor... § 1926.53 Ionizing radiation. (a) In construction and related activities involving the use of sources of ionizing radiation, the pertinent provisions of the Nuclear Regulatory Commission's Standards for...

RILIS-ionized mercury and tellurium beams at ISOLDE CERN

Energy Technology Data Exchange (ETDEWEB)

Day Goodacre, T., E-mail: thomas.day.goodacre@cern.ch [CERN (Switzerland); Billowes, J. [The University of Manchester, School of Physics and Astronomy (United Kingdom); Chrysalidis, K. [CERN (Switzerland); Fedorov, D. V. [Petersburg Nuclear Physics Institute (Russian Federation); Fedosseev, V. N.; Marsh, B. A. [CERN (Switzerland); Molkanov, P. L. [Petersburg Nuclear Physics Institute (Russian Federation); Rossel, R. E.; Rothe, S.; Seiffert, C. [CERN (Switzerland); Wendt, K. D. A. [Johannes Gutenberg Universität, Institut für Physik (Germany)

2017-11-15

This paper presents the results of ionization scheme development for application at the ISOLDE Resonance Ionization Laser Ion Source (RILIS). Two new ionization schemes for mercury are presented: a three-step three-resonance ionization scheme, ionizing via an excitation to a Rydberg level and a three-step two-resonance ionization scheme, with a non-resonant final step to the ionization continuum that corresponded to a factor of four higher ionization efficiency. The efficiency of the optimal mercury ionization scheme was measured, together with the efficiency of a new three-step three resonance ionization scheme for tellurium. The efficiencies of the mercury and tellurium ionization schemes were determined to be 6 % and >18 % respectively.

Impact of local electrostatic field rearrangement on field ionization

Science.gov (United States)

Katnagallu, Shyam; Dagan, Michal; Parviainen, Stefan; Nematollahi, Ali; Grabowski, Blazej; Bagot, Paul A. J.; Rolland, Nicolas; Neugebauer, Jörg; Raabe, Dierk; Vurpillot, François; Moody, Michael P.; Gault, Baptiste

2018-03-01

Field ion microscopy allows for direct imaging of surfaces with true atomic resolution. The high charge density distribution on the surface generates an intense electric field that can induce ionization of gas atoms. We investigate the dynamic nature of the charge and the consequent electrostatic field redistribution following the departure of atoms initially constituting the surface in the form of an ion, a process known as field evaporation. We report on a new algorithm for image processing and tracking of individual atoms on the specimen surface enabling quantitative assessment of shifts in the imaged atomic positions. By combining experimental investigations with molecular dynamics simulations, which include the full electric charge, we confirm that change is directly associated with the rearrangement of the electrostatic field that modifies the imaging gas ionization zone. We derive important considerations for future developments of data reconstruction in 3D field ion microscopy, in particular for precise quantification of lattice strains and characterization of crystalline defects at the atomic scale.

Investigation of the Effects of Facility Background Pressure on the Performance and Voltage-Current Characteristics of the High Voltage Hall Accelerator

Science.gov (United States)

Kamhawi, Hani; Huang, Wensheng; Haag, Thomas; Spektor, Rostislav

2014-01-01

The National Aeronautics and Space Administration (NASA) Science Mission Directorate In-Space Propulsion Technology office is sponsoring NASA Glenn Research Center to develop a 4 kW-class Hall thruster propulsion system for implementation in NASA science missions. A study was conducted to assess the impact of varying the facility background pressure on the High Voltage Hall Accelerator (HiVHAc) thruster performance and voltage-current characteristics. This present study evaluated the HiVHAc thruster performance in the lowest attainable background pressure condition at NASA GRC Vacuum Facility 5 to best simulate space-like conditions. Additional tests were performed at selected thruster operating conditions to investigate and elucidate the underlying physics that change during thruster operation at elevated facility background pressure. Tests were performed at background pressure conditions that are three and ten times higher than the lowest realized background pressure. Results indicated that the thruster discharge specific impulse and efficiency increased with elevated facility background pressure. The voltage-current profiles indicated a narrower stable operating region with increased background pressure. Experimental observations of the thruster operation indicated that increasing the facility background pressure shifted the ionization and acceleration zones upstream towards the thruster's anode. Future tests of the HiVHAc thruster are planned at background pressure conditions that are expected to be two to three times lower than what was achieved during this test campaign. These tests will not only assess the impact of reduced facility background pressure on thruster performance, voltage-current characteristics, and plume properties; but will also attempt to quantify the magnitude of the ionization and acceleration zones upstream shifting as a function of increased background pressure.

Thin films deposited by laser ablation for the measurement of the ionizing and non-ionizing radiation

International Nuclear Information System (INIS)

Villarreal B, J.E.; Escobar A, L.; Camps, E.; Romero, S.; Gonzalez, P.; Salinas, B.

2001-01-01

In this work the obtained results to synthesize thin films of amorphous carbon with incorporated nitrogen and hydrogen are presented, as well as thin films of aluminium oxide using the laser ablation technique. The thin films were exposed to ionizing radiation (gamma rays of a 60 Co source, beta radiation of a 90 Sr source) and a non-ionizing radiation (UV radiation). The obtained results show that it is possible to obtain materials in thin film form with thickness of hundreds of nanometers, which present thermoluminescent response when being irradiated with ionizing radiation and non-ionizing radiation. (Author)

Ionizing radiations

International Nuclear Information System (INIS)

Newton, W.

1984-01-01

The purpose of this article is to simplify some of the relevant points of legislation, biological effects and protection for the benefit of the occupational health nurse not familiar with the nuclear industries. The subject is dealt with under the following headings; Understanding atoms. What is meant by ionizing radiation. Types of ionizing radiation. Effects of radiation: long and short term somatic effects, genetic effects. Control of radiation: occupational exposure, women of reproductive age, medical aspects, principles of control. The occupational health nurse's role. Emergency arrangements: national arrangements for incidents involving radiation, action to be taken by the nurse. Decontamination procedures: external and internal contamination. (U.K.)

The effects of ionizing radiation on man

International Nuclear Information System (INIS)

Watson, G.M.

1975-08-01

This paper describes the major effects of ionizing radiation on man and the relationship between such effects and radiation dose, with the conclusion that standards of radiological safety must be based on the carcinogenetic and mutagenic properties of ionizing radiation. Man is exposed to radiation from natural sources and from man-made sources. Exposure from the latter should be regulated but, since there is little observational or experimental evidence for predicting the effects of the very small doses likely to be required for adequate standards of safety, it is necessary to infer them from what is seen at high doses. Because the formal relationship between dose and effect is not fully understood, simplifying assumptions are necessary to estimate the effects of low doses. Two such assumptions are conventionally used; that there is a linear relationship between dose and effect at all levels of dose, and that the rate at which a dose of radiation is given does not alter the magnitude of the effect. These assumptions are thought to be conservative, that is they will not lead to an underestimation of the effects of small radiation doses although they may give an over-estimate. (author)

Strategies for protection against exposure to ionizing radiation

International Nuclear Information System (INIS)

Goel, H.C.

2005-01-01

Radiations are known to be mutagenic, carcinogenic and cyto-lethal depending on the total dose, dose rate, quality of radiation and many other factors related to the person exposed. Therefore strategies for protection against exposure to ionizing radiations have to be accordingly planned. Radioprotection, though remains prophylactic in principle, includes mitigating and therapeutic modalities also. Initially, the central theme of biological radioprotection has been to protect against radiation-induced lethality and to optimize radiotherapy of tumours; the emphasis has now extended to cover many more situations of planned and unplanned nature. The central dogma of radioprotection work has been antioxidant action, which is relevant indeed against low LET radiation. The increasing understanding of the mechanism of radiation damage, however, permitted the advent of newer agents of both synthetic and natural origin. Sulfhydryl compounds like cysteamine, AET, Amifostine and endogenous molecules like GSH, SOD etc have been very important agents. Molecules like cytokines, immunomodulators, anti-inflammatory agents, angiotensin converting enzymes, metallo-elements and metallothionins, DNA ligands and Calcium antagonists have also been investigated recently. Unfortunately, no single agent could yield desired results especially due to toxicity at their radioprotective concentration. This led to the emergence of combinational modality where two or more agents working with different mechanisms could synergistically complement radioprotective action.. Recently, herbal extracts and dietary agents, which are the natural combinations of a large number of compounds that have important attributes to counter the damaging effects of ionizing radiations, have gained world-wide interest.. These agents have been found to be less toxic. Decorporation of radionuclei and protection against low dose chronic exposures like space flights and long haul inter-continental flights need to be

New constraints on the escape of ionizing photons from starburst galaxies using ionization-parameter mapping

International Nuclear Information System (INIS)

Zastrow, Jordan; Oey, M. S.; Veilleux, Sylvain; McDonald, Michael

2013-01-01

The fate of ionizing radiation in starburst galaxies is key to understanding cosmic reionization. However, the galactic parameters on which the escape fraction of ionizing radiation depend are not well understood. Ionization-parameter mapping provides a simple, yet effective, way to study the radiative transfer in starburst galaxies. We obtain emission-line ratio maps of [S III]/[S II] for six, nearby, dwarf starbursts: NGC 178, NGC 1482, NGC 1705, NGC 3125, NGC 7126, and He 2-10. The narrowband images are obtained with the Maryland-Magellan Tunable Filter at Las Campanas Observatory. Using these data, we previously reported the discovery of an optically thin ionization cone in NGC 5253, and here we also discover a similar ionization cone in NGC 3125. This latter cone has an opening angle of 40° ± 5° (0.4 sr), indicating that the passageways through which ionizing radiation may travel correspond to a small solid angle. Additionally, there are three sample galaxies that have winds and/or superbubble activity, which should be conducive to escaping radiation, yet they are optically thick. These results support the scenario that an orientation bias limits our ability to directly detect escaping Lyman continuum in many starburst galaxies. A comparison of the star formation properties and histories of the optically thin and thick galaxies is consistent with the model that high escape fractions are limited to galaxies that are old enough (≳3 Myr) for mechanical feedback to have cleared optically thin passageways in the interstellar medium, but young enough (≲5 Myr) that the ionizing stars are still present.

29 CFR 1910.1096 - Ionizing radiation.

Science.gov (United States)

2010-07-01

... 29 Labor 6 2010-07-01 2010-07-01 false Ionizing radiation. 1910.1096 Section 1910.1096 Labor... Ionizing radiation. (a) Definitions applicable to this section. (1) Radiation includes alpha rays, beta... the quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion of the...

Determination of natural radioactivity in beach sediments collected from Kovalam, Chennai

International Nuclear Information System (INIS)

Rajalakshmi, A.; Jananee, B.; Thangam, V.; Chandrasekaran, A.

2018-01-01

Long lived radioactive elements such as uranium, thorium, potassium and their decay products such as radium and radon are examples of naturally occurring radioactive materials abbreviated as NORM. All living things are exposed to ionizing radiation from NORM contributing to about 90% of human radiation exposure. The interaction of ionizing radiation with human body leads to several biological damages like leukemia, cancer etc due to damage and modification of cells and tissues in the body. Hence, the present work is carried out to determine the natural radioactivity of beach sediments along Kovalam Beach, Chennai. Associated parameters are also calculated

DNA-nuclear matrix interactions and ionizing radiation sensitivity

International Nuclear Information System (INIS)

Schwartz, J.L.; Vaughan, A.T.M.

1993-01-01

The association between inherent ionizing radiation sensitivity and DNA supercoil unwinding in mammalian cells suggests that the organization of the DNA in chromosomes plays an important role in radiation responses. In this paper, a model is proposed which suggests that these DNA unwinding alterations reflect differences in the attachment of DNA to the nuclear matrix. In radioresistant cells, the MAR structure might exist in a more stable, open configuration, limiting DNA unwinding following strand break induction and influencing the rate and nature of DNA double-strand break rejoining

The impact of urban background on appreciation of natural environments

OpenAIRE

Mirza, Leila; Linzey, Michael; Byrd, Hugh; Dodd, George

2012-01-01

For the first time in human history, more than half of the world's population live in towns and cities. The acceleration of habitat alteration as well as modern lifestyles dramatically reduce the interaction with natural environments. To get an overview of this issue, a comparison was made between individuals who lived most of their childhoods in high-rise blocks and who experienced nature on a daily basis from living and playing in suburbia or a rural environment. Can a lack of contact with ...

Effects of reduced natural background radiation on Drosophila melanogaster growth and development as revealed by the FLYINGLOW program.

Science.gov (United States)

Morciano, Patrizia; Iorio, Roberto; Iovino, Daniela; Cipressa, Francesca; Esposito, Giuseppe; Porrazzo, Antonella; Satta, Luigi; Alesse, Edoardo; Tabocchini, Maria Antonella; Cenci, Giovanni

2018-01-01

Natural background radiation of Earth and cosmic rays played a relevant role during the evolution of living organisms. However, how chronic low doses of radiation can affect biological processes is still unclear. Previous data have indicated that cells grown at the Gran Sasso Underground Laboratory (LNGS, L'Aquila) of National Institute of Nuclear Physics (INFN) of Italy, where the dose rate of cosmic rays and neutrons is significantly reduced with respect to the external environment, elicited an impaired response against endogenous damage as compared to cells grown outside LNGS. This suggests that environmental radiation contributes to the development of defense mechanisms at cellular level. To further understand how environmental radiation affects metabolism of living organisms, we have recently launched the FLYINGLOW program that aims at exploiting Drosophila melanogaster as a model for evaluating the effects of low doses/dose rates of radiation at the organismal level. Here, we will present a comparative data set on lifespan, motility and fertility from different Drosophila strains grown in parallel at LNGS and in a reference laboratory at the University of L'Aquila. Our data suggest the reduced radiation environment can influence Drosophila development and, depending on the genetic background, may affect viability for several generations even when flies are moved back to normal background radiation. As flies are considered a valuable model for human biology, our results might shed some light on understanding the effect of low dose radiation also in humans. © 2017 Wiley Periodicals, Inc.

Analytical form of current-voltage characteristic of parallel-plane, cylindrical and spherical ionization chambers with homogeneous ionization

Energy Technology Data Exchange (ETDEWEB)

Stoyanov, D G [Faculty of Engineering and Pedagogy in Sliven, Technical University of Sofia, 59, Bourgasko Shaussee Blvd, 8800 Sliven (Bulgaria)

2007-11-15

The elementary processes taking place in the formation of charged particles and their flow in parallel-plane, cylindrical and spherical geometry cases of ionization chamber are considered. On the basis of particles and charges balance a differential equation describing the distribution of current densities in the ionization chamber volume is obtained. As a result of the differential equation solution an analytical form of the current-voltage characteristic of an ionization chamber with homogeneous ionization is obtained. For the parallel-plane case comparision with experimental data is performed.

Analytical form of current-voltage characteristic of parallel-plane, cylindrical and spherical ionization chambers with homogeneous ionization

International Nuclear Information System (INIS)

Stoyanov, D G

2007-01-01

The elementary processes taking place in the formation of charged particles and their flow in parallel-plane, cylindrical and spherical geometry cases of ionization chamber are considered. On the basis of particles and charges balance a differential equation describing the distribution of current densities in the ionization chamber volume is obtained. As a result of the differential equation solution an analytical form of the current-voltage characteristic of an ionization chamber with homogeneous ionization is obtained. For the parallel-plane case comparision with experimental data is performed

Modeling ionization by helicon waves

International Nuclear Information System (INIS)

Degeling, A.W.; Boswell, R.W.

1997-01-01

The response of the electron distribution function in one dimension to a traveling wave electric field is modeled for parameters relevant to a low-pressure helicon wave plasma source, and the resulting change in the ionization rate calculated. This is done by calculating the trajectories of individual electrons in a given wave field and assuming no collisions to build up the distribution function as the distance from the antenna is increased. The ionization rate is calculated for argon by considering the ionization cross section and electron flux at a specified position and time relative to the left-hand boundary, where the distribution function is assumed to be Maxwellian and the wave travels to the right. The simulation shows pulses in the ionization rate that move away from the antenna at the phase velocity of the wave, demonstrating the effect of resonant electrons trapped in the wave close-quote s frame of reference. It is found that the ionization rate is highest when the phase velocity of the wave is between 2 and 3x10 6 m/s, where the electrons interacting strongly with the wave (i.e., electrons with velocities inside the wave close-quote s open-quotes trapping widthclose quotes) have initial energies just below the ionization threshold. Results from the model are compared with experimental data and show reasonable qualitative agreement. copyright 1997 American Institute of Physics

Tissue macrophage activation: a shared sign of exposure to ionizing and non-ionizing radiation

International Nuclear Information System (INIS)

Petrenyov, D.R.

2012-01-01

The features of oxidative metabolism of peritoneal macrophages were studied in rats exposed to ionizing and non-ionizing radiation. An increased RNS and ROS production reported in animals exposed to both source of radiation showing non-specific response of organism. (authors)

Random distribution of background charge density for numerical simulation of discharge inception

International Nuclear Information System (INIS)

Grange, F.; Loiseau, J.F.; Spyrou, N.

1998-01-01

The models of electric streamers based on a uniform background density of electrons may appear not to be physical, as the number of electrons in the small active region located in the vicinity of the electrode tip under regular conditions can be less than one. To avoid this, the electron background is modelled by a random density distribution such that, after a certain time lag, at least one electron is present in the grid close to the point electrode. The modelling performed shows that the streamer inception is not very sensitive to the initial location of the charged particles; the ionizing front, however, may be delayed by several tens of nanoseconds, depending on the way the electron has to drift before reaching the anode. (J.U.)

Ionization efficiency calculations for cavity thermoionization ion source

International Nuclear Information System (INIS)

Turek, M.; Pyszniak, K.; Drozdziel, A.; Sielanko, J.; Maczka, D.; Yuskevich, Yu.V.; Vaganov, Yu.A.

2009-01-01

The numerical model of ionization in a thermoionization ion source is presented. The review of ion source ionization efficiency calculation results for various kinds of extraction field is given. The dependence of ionization efficiency on working parameters like ionizer length and extraction voltage is discussed. Numerical simulations results are compared to theoretical predictions obtained from a simplified ionization model

Estimation and comparison of baseline frequencies of micronuclei among the new-borns from natural high background radiation and control areas of Kerala coast in south India

International Nuclear Information System (INIS)

Das, Birajalaxmi; Karuppasamy, C.V.; Thampi, M.V.

1994-01-01

Based on the studies it is concluded that the elevated level of natural radiation has no significant effect of micronucleus formation in high background radiation area (HBRA) new-borns as compared to control area. It is also in agreement with the results of cytogenetic investigations on new-borns from HBRA and control area using chromosome aberration analysis method. The significance, if any, of the slightly lower micronuclei (MN) frequency observed in HBRA, is not clear at this stage. Further investigations on a larger number of new-borns from both the areas are necessary in order to draw firm conclusions. It appears that, this is the first attempt to estimate the baseline frequency of MN among the new-borns from a natural high background radiation area. (author). 9 refs

A study of the effects of therapeutic doses of ionizing radiation in vitro on Lactobacillus isolates originating from the vagina - a pilot study

OpenAIRE

Gosiewski, Tomasz; Mr?z, Tomasz; Ocho?ska, Dorota; Pabian, Wojciech; Bulanda, Malgorzata; Brzychczy-Wloch, Monika

2016-01-01

Background Ionizing radiation is used as a therapeutic option in the treatment of certain neoplastic lesions located, among others, in the pelvic region. The therapeutic doses of radiation employed often result in adverse effects manifesting themselves primarily in the form of genital tract infections in patients or diarrhea. The data available in the literature indicate disorders in the microbial ecosystem caused by ionizing radiation, which leads to the problems mentioned above. In the pres...

The first detection of ionized helium in the local ISM - EUVE and IUE spectroscopy of the hot DA white dwarf GD 246

Science.gov (United States)

Vennes, Stephane; Dupuis, Jean; Rumph, Todd; Drake, Jeremy; Bowyer, Stuart; Chayer, Pierre; Fontaine, Gilles

1993-01-01

We report observations of the extreme ultraviolet spectrum of the hot degenerate star GD 246 obtained with the EUVE. Our initial attempt at modeling the photospheric emission from the white dwarf reveals a relatively uncontaminated pure H spectrum in the range above 200 A, allowing a study of interstellar continuum absorption features in the line of sight of GD 246. Modeling of the He I autoionization transition discussed by Rumph et al. (1993), and the EUV continuum using the white dwarf as a source of background radiation provides measurements of both neutral and, for the first time, singly ionized He column densities in the local ISM (LISM). We estimate the He ionization fraction He II/(He I + He II) at roughly 25 percent with a total He column of 1.40-1.65 x 10 exp 18/sq cm. We have measured and compared H I column densities from the saturated Ly-alpha ISM absorption in IUE high-dispersion spectroscopy and from EUV continuum absorption: the two measurements are in good agreement with a total H column of 1.2-1.6 x 10 exp 19/sq cm. We discuss some implications for the nature of the LISM, particularly in the context of current models of the EUV radiation field.

Mortality from diseases other than cancer following low doses of ionizing radiation

DEFF Research Database (Denmark)

Vrijheid, M; Cardis, E; Ashmore, P

2007-01-01

BACKGROUND: Ionizing radiation at very high (radio-therapeutic) dose levels can cause diseases other than cancer, particularly heart diseases. There is increasing evidence that doses of the order of a few sievert (Sv) may also increase the risk of non-cancer diseases. It is not known, however......, whether such effects also occur following the lower doses and dose rates of public health concern. METHODS: We used data from an international (15-country) nuclear workers cohort study to evaluate whether mortality from diseases other than cancer is related to low doses of external ionizing radiation....... Analyses included 275 312 workers with adequate information on socioeconomic status, over 4 million person-years of follow-up and an average cumulative radiation dose of 20.7 mSv; 11 255 workers had died of non-cancer diseases. RESULTS: The excess relative risk (ERR) per Sv was 0.24 [95% CI (confidence...

Cellular and molecular effects of natural background radiation on human population in Kerala coast, India: from chromosome ends to transcriptome

Energy Technology Data Exchange (ETDEWEB)

Das, Birajalaxmi; Jain, Vinay; Saini, Divyalakshmi; Ghosh, Anu; Seshadri, M. [Radiation Biology and Health Sciences Division, Bio-Medical Group, Bhabha Atomic Research Centre, Mumbai (India); Sandhya Kiran, P. [Ocimum Biosolutions India Limited, Hyderabad (India)

2010-07-01

Venous blood samples of 32 male volunteers (age group 35-45 years) from different background dose groups. Factors like life style, smoking, drinking alcohol, chewing, previous exposure to radiation and medical history etc. were properly recorded. Microarray analysis was performed using Affymetrix FlGU133 plus 2.0 chip and the expression level of 54,675 genes were obtained for each sample. In order to assess the effect of chronic natural background radiation we have categorized our samples into four groups. To derive genes that are differentially regulated between these four groups, 'Exposed group versus Control' was set up and the linear model was fitted to each gene using the expression data on samples. A fold change threshold of 1.3, 1.5 and 2.0 and an adjusted p-value threshold of 0.05 was set in the study. Analysis was done using 'limma' library of R and Genowiz.

Cellular and molecular effects of natural background radiation on human population in Kerala coast, India: from chromosome ends to transcriptome

International Nuclear Information System (INIS)

Das, Birajalaxmi; Jain, Vinay; Saini, Divyalakshmi; Ghosh, Anu; Seshadri, M.; Sandhya Kiran, P.

2010-01-01

Venous blood samples of 32 male volunteers (age group 35-45 years) from different background dose groups. Factors like life style, smoking, drinking alcohol, chewing, previous exposure to radiation and medical history etc. were properly recorded. Microarray analysis was performed using Affymetrix FlGU133 plus 2.0 chip and the expression level of 54,675 genes were obtained for each sample. In order to assess the effect of chronic natural background radiation we have categorized our samples into four groups. To derive genes that are differentially regulated between these four groups, 'Exposed group versus Control' was set up and the linear model was fitted to each gene using the expression data on samples. A fold change threshold of 1.3, 1.5 and 2.0 and an adjusted p-value threshold of 0.05 was set in the study. Analysis was done using 'limma' library of R and Genowiz

Epidemiological studies on the effects of low-level ionizing radiation on cancer risk

International Nuclear Information System (INIS)

Akiba, Suminori

2010-01-01

The health effects of low-level ionizing radiation are yet unclear. As pointed out by Upton in his review (Upton, 1989), low-level ionizing radiation seems to have different biological effects from what high-level radiation has. If so, the hazard identification of ionizing radiation should he conducted separately for low- and high-level ionizing radiation; the hazard identification of low-level radiation is yet to be completed. What makes hazard identification of ionizing radiation difficult, particularly in the case of carcinogenic effect, is the difficulty in distinguishing radiation-induced cancer from other cancers with respect to clinicopathological features and molecular biological characteristics. Actually, it is suspected that radiation-induced carcinogenesis involves mechanisms not specific for radiation, such as oxidative stress. Excess risk per dose in medium-high dose ranges can be extrapolated to a low-dose range if dose-response can be described by the linear-non-threshold model. The cancer risk data of atomic-bomb survivors describes leukemia risk with a linear-quadratic (LQ) model and solid-cancer risk with linear non-threshold (LNT) model. The LQ model for leukemia and the LNT model for solid cancer correspond to the two-hit model and the one-hit model, respectively. Although the one-hit model is an unlikely dose-response for carcinogenesis, there is no convincing epidemiological evidence supporting the LQ model or non-threshold model for solid cancer. It should be pointed out, however, even if the true dose response is non-linear various noises involved in epidemiological data may mask the truth. In this paper, the potential contribution of epidemiological studies on nuclear workers and residents in high background radiation areas will be discussed. (author)

Giant resonance phenomena in the electron impact ionization of heavy atoms and ions

International Nuclear Information System (INIS)

Younger, S.M.

1986-01-01

Heavy atoms and ions offer an interesting opportunity to study atomic physics in a region where the atomic structure is dominated by the interelectronic interactions. One illustration of this is the profound term dependence of atomic orbitals for certain configurations of heavy atoms and ions. The appearance of giant scattering resonances in the cross sections for ionization of heavy atoms by electron impact is a manifestation of resonance behavior. Such resonant structures arise from the double well nature of the scattering potential and have recently been identified in the cross sections for the electron impact ionization of several xenon-like ions. The results of calculations showing effects for a variety of other ions are summarized. 7 refs., 4 figs

Space Weather Nowcasting of Atmospheric Ionizing Radiation for Aviation Safety

Science.gov (United States)

Mertens, Christopher J.; Wilson, John W.; Blattnig, Steve R.; Solomon, Stan C.; Wiltberger, J.; Kunches, Joseph; Kress, Brian T.; Murray, John J.

2007-01-01

There is a growing concern for the health and safety of commercial aircrew and passengers due to their exposure to ionizing radiation with high linear energy transfer (LET), particularly at high latitudes. The International Commission of Radiobiological Protection (ICRP), the EPA, and the FAA consider the crews of commercial aircraft as radiation workers. During solar energetic particle (SEP) events, radiation exposure can exceed annual limits, and the number of serious health effects is expected to be quite high if precautions are not taken. There is a need for a capability to monitor the real-time, global background radiations levels, from galactic cosmic rays (GCR), at commercial airline altitudes and to provide analytical input for airline operations decisions for altering flight paths and altitudes for the mitigation and reduction of radiation exposure levels during a SEP event. The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model is new initiative to provide a global, real-time radiation dosimetry package for archiving and assessing the biologically harmful radiation exposure levels at commercial airline altitudes. The NAIRAS model brings to bear the best available suite of Sun-Earth observations and models for simulating the atmospheric ionizing radiation environment. Observations are utilized from ground (neutron monitors), from the atmosphere (the METO analysis), and from space (NASA/ACE and NOAA/GOES). Atmospheric observations provide the overhead shielding information and the ground- and space-based observations provide boundary conditions on the GCR and SEP energy flux distributions for transport and dosimetry simulations. Dose rates are calculated using the parametric AIR (Atmospheric Ionizing Radiation) model and the physics-based HZETRN (High Charge and Energy Transport) code. Empirical models of the near-Earth radiation environment (GCR/SEP energy flux distributions and geomagnetic cut-off rigidity) are benchmarked

Induction of hepatocyte polyploidization in rats of different age by ionizing radiation of different LET

International Nuclear Information System (INIS)

Gil'yano, N.Ya.; Malinovskij, O.V.; Khair, M.B.

1992-01-01

A decrease in the effectiveness of neutron-irradiation with respect to fusion of nonproliferating hepatocytes of animals with age was shown by the method of flow cytometry. There was an inverse relationship between the effectiveness of induction of non-proliferating hepatocytes fusion and neutron energy. The process of hepatocyte fusion induced by neutrons was inhibited by uranyl acetate. No age-dependent changes were noted in the induction of polyploidization of proliferating hepatocytes by sparsely ionizing radiation. A hypothesis is proposed concerning a membrane nature of the target responsible for hepatocyte polyploidization induced by densely ionizing radiation. (authors). 8 refs., 4 figs., 5 tabs

Induction of hepatocyte polyploidization in rats of different age by ionizing radiation of different LET

International Nuclear Information System (INIS)

Gil'yano, N.Ya.; Malinovskij, O.V.; Khair, M.B.

1990-01-01

A decrease in the effectiveness of neutron-irradiation with respect to fusion of nonproliferating hepatocytes of animals with age was shown by the method of flow cytometry. There was an inverse relationship between the effectiveness of induction of non-proliferating hepatocytes fusion and neutron energy. The process of hepatocyte fusion induced by neutrons was inhibited by uranyl acetate. No age-dependent changes were noted in the induction of polyploidization of proliferating hepatocytes by sparsely ionizing radiation. A hypothesis is proposed concerning a membrane nature of the target responsible for hepatocyte polyploidization induced by densely ionizing radiation

The influence of vegetable bioactive compounds on systemic immune reactions to ionizing radiation action

International Nuclear Information System (INIS)

Coretchi, Liuba; Plavan, Irina; Bahnarel, Ion; Rosca, Andrei

2015-01-01

The paper presents the summary of the scientific results analysis of the published in the last 10 years studies of the influence of secondary metabolites essential oils and essential-oil plants extracts, on the resistance/sensitivity of the animal and human body to the action of ionizing radiation. An essential problem is the development of new nanotechnologies for mitigation the onset of side effects caused by the use of ionizing radiation therapy of patients with different types of cancer. Widespread application of phyto therapy empiric reveals the beneficial effect of essential oils and essential-oil plants extracts on the immune system. The considered substances have natural antioxidant properties and contribute to the elimination of free radicals which are formed in the body under the action of stress, including ionizing radiation. This reveals about their use in mitigation of ionizing radiation action effects, as a radio protector agent. Unlike other preparations, used to activate the immune system, essential oils at low concentrations show a long-lasting system immune stimulation action. More of that, during their administration the onset of adverse reactions have not been demonstrated. (authors)

Improvements in ionization chambers

International Nuclear Information System (INIS)

Whetten, N.R.; Zubal, C.

1980-01-01

A method of reducing mechanical vibrations transmitted to the parallel plate electrodes of ionization chamber x-ray detectors, commonly used in computerized x-ray axial tomography systems, is described. The metal plate cathodes and anodes are mounted in the ionizable gas on dielectric sheet insulators consisting of a composite of silicone resin and glass fibres. (UK)

Fine- and hyperfine-structure effects in molecular photoionization. II. Resonance-enhanced multiphoton ionization and hyperfine-selective generation of molecular cations

Energy Technology Data Exchange (ETDEWEB)

Germann, Matthias; Willitsch, Stefan, E-mail: stefan.willitsch@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland)

2016-07-28

Resonance-enhanced multiphoton ionization (REMPI) is a widely used technique for studying molecular photoionization and producing molecular cations for spectroscopy and dynamics studies. Here, we present a model for describing hyperfine-structure effects in the REMPI process and for predicting hyperfine populations in molecular ions produced by this method. This model is a generalization of our model for fine- and hyperfine-structure effects in one-photon ionization of molecules presented in Paper I [M. Germann and S. Willitsch, J. Chem. Phys. 145, 044314 (2016)]. This generalization is achieved by covering two main aspects: (1) treatment of the neutral bound-bound transition including the hyperfine structure that makes up the first step of the REMPI process and (2) modification of our ionization model to account for anisotropic populations resulting from this first excitation step. Our findings may be used for analyzing results from experiments with molecular ions produced by REMPI and may serve as a theoretical background for hyperfine-selective ionization experiments.

New ionization fractions for the lithium- and helium-like ionization stages of calcium and iron

International Nuclear Information System (INIS)

Doyle, J.G.; Raymond, J.C.

1981-01-01

The high resolution X-ray spectra of Ca XIX and Fe XXV observed during a solar flare on 1979 March 25 have been re-interpreted using new ionization fractions for Ca XVIII, Ca XIX, Fe XXIV and Fe XXV. These new calculations substantially change the interpretation of the spectra, implying the flare to be ionizing during the rise phase and recombining during the decay phase. The results favour the ECIP ionization rates over those of Lotz, though other interpretations are possible. (author)

Ionization chamber

International Nuclear Information System (INIS)

1977-01-01

An improved ionization chamber type X-ray detector comprises a heavy gas at high pressure disposed between an anode and a cathode. An open grid structure is placed next to the anode and is maintained at a voltage intermediate between the cathode and anode potentials. The electric field which is produced by positive ions drifting towards the cathode is thus shielded from the anode. Current measuring circuits connected to the anode are, therefore, responsive only to electron current flow within the chamber and the recovery time of the chamber is shortened. The grid structure also serves to shield the anode from electrical currents which might otherwise be induced by mechanical vibrations in the ionization chamber structure

Photoionization effects in ionization fronts

International Nuclear Information System (INIS)

Arrayas, Manuel; Fontelos, Marco A; Trueba, Jose L

2006-01-01

In this paper we study the effects of photoionization processes on the propagation of both negative and positive ionization fronts in streamer discharge. We show that negative fronts accelerate in the presence of photoionization events. The appearance and propagation of positive ionization fronts travelling with constant velocity is explained as the result of the combined effects of photoionization and electron diffusion. The photoionization range plays an important role in the selection of the velocity of the ionization front as we show in this work

Photoionization effects in ionization fronts

Energy Technology Data Exchange (ETDEWEB)

Arrayas, Manuel [Departamento de Electromagnetismo, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain); Fontelos, Marco A [Departamento de Matematicas, Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones CientIficas, C/Serrano 123, 28006 Madrid (Spain); Trueba, Jose L [Departamento de Electromagnetismo, Universidad Rey Juan Carlos, Tulipan s/n, 28933 Mostoles, Madrid (Spain)

2006-12-21

In this paper we study the effects of photoionization processes on the propagation of both negative and positive ionization fronts in streamer discharge. We show that negative fronts accelerate in the presence of photoionization events. The appearance and propagation of positive ionization fronts travelling with constant velocity is explained as the result of the combined effects of photoionization and electron diffusion. The photoionization range plays an important role in the selection of the velocity of the ionization front as we show in this work.

WIDE-FIELD VLBI OBSERVATIONS OF M31: A UNIQUE PROBE OF THE IONIZED INTERSTELLAR MEDIUM OF A NEARBY GALAXY

International Nuclear Information System (INIS)

Morgan, John S.; Argo, Megan K.; Trott, Cathryn M.; Macquart, Jean-Pierre; Miller-Jones, James; Tingay, Steven J.; Deller, Adam; Middelberg, Enno

2013-01-01

The Very Long Baseline Array was used at 1.6 GHz to observe a target field 50' in diameter including the core of M31. Novel very long baseline interferometry correlation techniques were used to observe 200 sources simultaneously, of which 16 were detected. We classify all 16 as background active galactic nuclei based on their X-ray properties and arcsecond- and mas-scale morphology. The detected sources were then analyzed for evidence of scatter-broadening due to the ionized interstellar medium (ISM) of M31. The detection of a compact background source only 0.25 kpc projected distance from M31* places a constraint on the extent of any extreme scattering region associated with the center of M31. However, the two sources closest to the core show evidence of scatter broadening consistent with that which would be seen for a compact source if it were observed through the inner disk of our Galaxy, at the inclination of M31. We interpret this as a detection of the ionized ISM of M31 along two lines of sight. With the increases in bandwidth and sensitivity envisaged for future long-baseline interferometers, this should prove to be a remarkably powerful technique for understanding the ionized ISM in external galaxies.

A semi-empirical concept for the calculation of electron-impact ionization cross sections of neutral and ionized fullerenes

International Nuclear Information System (INIS)

Deutsch, H.; Scheier, P.; Maerk, T.D.; Becker, K.

2002-01-01

A semi-empirical approach to the calculation of cross section functions (absolute value and energy dependence) for the electron-impact ionization of several neutral and ionized fullerenes C 60 n+ (n =0-3) was developed, for which reliable experimental data have been reported. In particular, it is proposed a modification of the simplistic assumption that the ionization cross section of a cluster/fullerene is given as the product of the monomer ionization cross section and a factor m a , where 'm' is the number of monomers in the ensemble and 'a' is a constant. A comparison between these calculations and the available experimental data reveals good agreement for n = 0,103. In the case of ionization of C 60 2+ (n = 2) the calculation lies significantly below the measured cross section which it was interpret as an indication that additional indirect ionization processes are present for this charge state. (nevyjel)

On possible structures of transverse ionizing shock waves

International Nuclear Information System (INIS)

Liberman, M.A.; Velikovich, A.L.

1978-01-01

The possible structures of ionizing shock waves propagating in gases across the magnetic field are investigated taking account of both ionization kinetics and the non-isothermality of the plasma which is formed within the shock front. It is shown that a definite factor in shaping the structure of the transverse ionizing shock wave is photo-ionization of the neutral gas across the front. The paper includes a study of the evolution of the transverse ionizing shock front with regard to photo-ionization, disclosing that a stable stationary shock structure emerges only in boundary conditions which are close to magnetohydrodynamic ones, i.e. upsilon 1 H 1 = upsilon 2 H 2 . In the case of strong transverse ionizing shock waves, when the flux of ionizing radiation across the front is great, the shock structure is obviously magnetohydrodynamic. (author)

Electrostatic perturbations in partially ionized plasma with the effects of ionization and recombination

International Nuclear Information System (INIS)

Vranjes, J.; Tanaka, M.Y.; Kono, M.; Poedts, S.

2004-01-01

The behavior of the electrostatic ion acoustic mode in a partially ionized plasma is studied in the presence of collisions which involve processes of ionization and recombination, taking into account the dynamics of the neutrals caused by elastic and inelastic collisions with ions. The application of the model to space plasmas, which are usually subject to gravity, is discussed in detail. A dispersion equation which includes the effects of ionization and recombination is derived and the stability/instability conditions are discussed. Parameters applicable to a region of the upper solar chromosphere are used and the increment of the ion sound wave is calculated yielding an unstable ion sound wave for wavelengths larger than 20 km

Mutagenic action of non-ionizing radiations: its implication in radiation protection

International Nuclear Information System (INIS)

Madhvanath, U.; Subrahmanyam, P.; Sankaranarayanan, N.; Singh, D.R.

1977-01-01

Mutagenic effects of non-ionizing radiations except in the ultraviolet and near ultraviolet region are just not known. Results of the investigation carried out using a sensitive diploid yeast system, are presented. The arginine requiring mutant yeast strain BZ34 reverts to prototrophy following exposure to ionizing radiation. Reversion frequencies were determined following exposure to UV (254 nm), near ultraviolet (313, 353 nm) visible region (480 nm), neodymium laser (1.01 μm) and microwave (2450 MHz) radiations. An Aminco - Bowman Spectrophotofluorimeter was used to obtain wavelengths from UV to visible region. Yeast suspensions (concentration of 10 7 cells/ml) were irradiated to doses ranging from 10 7 to 10 9 erg/cm 3 as determined with potassium ferri-oxalate system. Exposure to laser pulses and microwave radiation ranged up to 45 J/cm 2 and 60 mW-h/cm 2 respectively. Results showed that the reversion induction efficiency decreased by six orders of magnitude from ionizing radiations to ultraviolet for the same absorbed dose and this efficiency has further decreased by a factor of fifteen when the wavelength is increased from 254 nm to 313 nm. Although killing could be effected with laser beams (45 J/cm 2 for 50% survival) no increase in the reversion was observed than the background level. It is concluded that radiation of wavelengths higher than 450 nm up to 12 cm studied is not mutagenic and with sufficient intensities of these radiations only killing of cells is possible due to thermal effects. This finding is compared with other known functional and morphological effects at cellular level due to low-level exposures of non-ionizing radiations