WorldWideScience

Sample records for radiation field size

  1. Response dependence of a ring ionization chamber response on the size of the X radiation field

    International Nuclear Information System (INIS)

    Yoshizumi, Maira T.; Caldas, Linda V.E.

    2009-01-01

    A ring monitor ionization chamber was developed at the IPEN-Sao Paulo, Brazil, fixed on a system of collimators which determine the dimension of the radiation field size. This work verified that the ring chamber response depends on the exponential form with the size of de radiation field

  2. Size measurement of radioactive aerosol particles in intense radiation fields using wire screens and imaging plates

    Energy Technology Data Exchange (ETDEWEB)

    Oki, Yuichi; Tanaka, Toru; Takamiya, Koichi; Ishi, Yoshihiro; UesugI, Tomonori; Kuriyama, Yasutoshi; Sakamoto, Masaaki; Ohtsuki, Tsutomu [Kyoto University Research Reactor Institute, Osaka (Japan); Nitta, Shinnosuke [Graduate School of Engineering, Kyoto University, Kyoto (Japan); Osada, Naoyuki [Advanced Science Research Center, Okayama University, Okayama (Japan)

    2016-09-15

    Very fine radiation-induced aerosol particles are produced in intense radiation fields, such as high-intensity accelerator rooms and containment vessels such as those in the Fukushima Daiichi nuclear power plant (FDNPP). Size measurement of the aerosol particles is very important for understanding the behavior of radioactive aerosols released in the FDNPP accident and radiation safety in high-energy accelerators. A combined technique using wire screens and imaging plates was developed for size measurement of fine radioactive aerosol particles smaller than 100 nm in diameter. This technique was applied to the radiation field of a proton accelerator room, in which radioactive atoms produced in air during machine operation are incorporated into radiation-induced aerosol particles. The size of 11C-bearing aerosol particles was analyzed using the wire screen technique in distinction from other positron emitters in combination with a radioactive decay analysis. The size distribution for 11C-bearing aerosol particles was found to be ca. 70 μm in geometric mean diameter. The size was similar to that for 7Be-bearing particles obtained by a Ge detector measurement, and was slightly larger than the number-based size distribution measured with a scanning mobility particle sizer. The particle size measuring method using wire screens and imaging plates was successfully applied to the fine aerosol particles produced in an intense radiation field of a proton accelerator. This technique is applicable to size measurement of radioactive aerosol particles produced in the intense radiation fields of radiation facilities.

  3. Radiation field sizes and skin exposures in oral radiography

    International Nuclear Information System (INIS)

    Hazin, C.A.; Khoury, H.J.; Silveira, S.V.; Lopes Filho, F.J.

    1996-01-01

    The increasing use of X-rays in preventive and diagnostic dentistry in Brazil has been cause of concern because dentists, in general, are not acquainted with the basic principles of radiation protection. Recently, the Brazilian Ministry of Health has urged the Departments of Health at the state level to develop actions to register dental X-ray units in their areas of jurisdiction and to issue operating permits to those facilities which satisfy some basic technical requirements. On the basis of these recommendations the Instituto de Radioprotecao e Dosimetria of the Brazilian Commission of Nuclear Energy has initiated a postal programme to assess the performance of dental X-ray sets in the State of Rio de Janeiro. The postal kit used in that survey was similar to the one developed by the Bureau of Radiological Health of the US Dept. of Health, Education, and Welfare. In continuation to that study, the Nuclear Energy Dept. of the Federal Univ. of Pernambuco initiated a survey of dental X-ray apparatus to evaluate the operating conditions of that kind of equipment in Recife, the capital of the State of Pernambuco. The objectives of the survey were: a) to assess the degree of compliance of the equipment and procedures adopted by the dental practitioners in Recife with the accepted radiation protection standards, and b) to estimate the magnitude of the exposure to the patient resulting from a typical dental radiographic procedure. (author)

  4. Field size dependent mapping of medical linear accelerator radiation leakage

    International Nuclear Information System (INIS)

    Vu Bezin, Jérémi; De Vathaire, Florent; Diallo, Ibrahima; Veres, Attila; Lefkopoulos, Dimitri; Chavaudra, Jean; Deutsch, Eric

    2015-01-01

    The purpose of this study was to investigate the suitability of a graphics library based model for the assessment of linear accelerator radiation leakage. Transmission through the shielding elements was evaluated using the build-up factor corrected exponential attenuation law and the contribution from the electron guide was estimated using the approximation of a linear isotropic radioactive source. Model parameters were estimated by a fitting series of thermoluminescent dosimeter leakage measurements, achieved up to 100 cm from the beam central axis along three directions. The distribution of leakage data at the patient plane reflected the architecture of the shielding elements. Thus, the maximum leakage dose was found under the collimator when only one jaw shielded the primary beam and was about 0.08% of the dose at isocentre. Overall, we observe that the main contributor to leakage dose according to our model was the electron beam guide. Concerning the discrepancies between the measurements used to calibrate the model and the calculations from the model, the average difference was about 7%. Finally, graphics library modelling is a readily and suitable way to estimate leakage dose distribution on a personal computer. Such data could be useful for dosimetric evaluations in late effect studies. (paper)

  5. Dynamics of moving interacting atoms in a laser radiation field and optical size resonances

    International Nuclear Information System (INIS)

    Gadomskii, O.N.; Glukhov, A.G.

    2005-01-01

    The forces acting on interacting moving atoms exposed to resonant laser radiation are calculated. It is shown that the forces acting on the atoms include the radiation pressure forces as well as the external and internal bias forces. The dependences of the forces on the atomic spacing, polarization, and laser radiation frequency are given. It is found that the internal bias force associated with the interaction of atomic dipoles via the reemitted field may play an important role in the dynamics of dense atomic ensembles in a light field. It is shown that optical size resonances appear in the system of interacting atoms at frequencies differing substantially from transition frequencies in the spectrum of atoms. It is noted that optical size resonances as well as the Doppler frequency shift in the spectrum of interacting atoms play a significant role in the processes of laser-radiation-controlled motion of the atoms

  6. Effect of organ size and position on out-of-field dose distributions during radiation therapy

    International Nuclear Information System (INIS)

    Scarboro, Sarah B; White, Allen; Yaldo, Derek; Kry, Stephen F; Howell, Rebecca M; Stovall, Marilyn; Smith, Susan A

    2010-01-01

    Mantle field irradiation has historically been the standard radiation treatment for Hodgkin lymphoma. It involves treating large regions of the chest and neck with high doses of radiation (up to 30 Gy). Previous epidemiological studies on the incidence of second malignancies following radiation therapy for Hodgkin lymphoma have revealed an increased incidence of second tumors in various organs, including lung, breast, thyroid and digestive tract. Multiple other studies, including the Surveillance, Epidemiology and End Results, indicated an increased incidence in digestive tract including stomach cancers following mantle field radiotherapy. Assessment of stomach dose is challenging because the stomach is outside the treatment field but very near the treatment border where there are steep dose gradients. In addition, the stomach can vary greatly in size and position. We sought to evaluate the dosimetric impact of the size and variable position of the stomach relative to the field border for a typical Hodgkin lymphoma mantle field irradiation. The mean stomach dose was measured using thermoluminescent dosimetry for nine variations in stomach size and position. The mean doses to the nine stomach variations ranged from 0.43 to 0.83 Gy when 30 Gy was delivered to the treatment isocenter. Statistical analyses indicated that there were no significant differences in the mean stomach dose when the stomach was symmetrically expanded up to 3 cm or shifted laterally (medial, anterior or posterior shifts) by up to 3 cm. There was, however, a significant (P > 0.01) difference in the mean dose when the stomach was shifted superiorly or inferiorly by ≥2.5 cm.

  7. Analysis of Radiation Field and Block Pattern for Optimal Size in Multileaf Collimator

    International Nuclear Information System (INIS)

    Ahn, Seoung Do; Yang, Kwang Mo; Yi, Byong Yong; Choi, Eun Kyong; Chang, Hye Sook

    1994-01-01

    The patterns of the conventional radiation treatment fields and their shielding blocks are analysed to determine the optimal dimension of the MultiLeaf Collimator (MLC) which is considered as an essential tool for conformal therapy. Total 1169 radiation fields from 303 patients (203 from Asan Medical center, 50 from Baek Hosp and 50 from Hanyang Univ. Hosp.) were analysed for this study. Weighted case selection treatment site (from The Korean Society of Therapeutic Radiology 1003). Ninety one percent of total fields have shielding blocks. Y axis is defined as leaf movement direction and it is assumed that MLC is installed on the cranial-caudal direction. The length of X axis were distributed from 4cm to 40cm (less than 21cm for 95% of cases), and Y axis from 5cm to 38cm (less than 22cm for 95% of cases). The shielding blocks extended to less than 6cm from center of the filed for 95% of the cases. Start length for ninety five percent of block is less than 10cm for X axis and 11cm for Y axis. Seventy six percent of shielding blocks could be placed by either X or Y axis direction, 7.9% only by Y axis, 5.1% only by X axis and it is reasonable to install MLC for Y direction. Ninety five percent of patients can be treated with coplanar rotation therapy without changing the collimator angle. Eleven percent of cases of cases were impossible to replace with MLC. Futher study of shielding should be larger than 21cm X 22cm. The MLC should be designed as a pair of 21 leaves with 1cm wide for an acceptable resolution and 17cm long to enable the leaf to overtravel at least 6cm from the treatment field center

  8. Generation of auroral kilometric radiation by a finite-size source in a dipole magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Burinskaya, T. M., E-mail: tburinsk@iki.rssi.ru; Shevelev, M. M. [Russian Academy of Sciences, Space Research Institute (Russian Federation)

    2016-10-15

    Generation, amplification, and propagation of auroral kilometric radiation in a narrow three-dimensional plasma cavity in which a weakly relativistic electron beam propagates is studied in the geometrical optics approximation. It is shown that the waves that start with a group velocity directed earthward and have optimal relation between the wave vector components determining the linear growth rate and the wave residence time inside the amplification region undergo the largest amplification. Taking into account the longitudinal velocity of fast electrons results in the shift of the instability domain toward wave vectors directed to the Earth and leads to a change in the dispersion relation, due to which favorable conditions are created for the generation of waves with frequencies above the cutoff frequency for the cold background plasma at the wave generation altitude. The amplification factor for these waves is lower than for waves that have the same wave vectors but are excited by the electron beams with lower velocities along the magnetic field. For waves excited at frequencies below the cutoff frequency of the background plasma at the generation altitude, the amplification factor increases with increasing longitudinal electron velocity, because these waves reside for a longer time in the amplification region.

  9. A study on quantitative analysis of field size and dose by using gating system in 4D conformal radiation treatment

    Science.gov (United States)

    Ji, Youn-Sang; Dong, Kyung-Rae; Kim, Chang-Bok; Chung, Woon-Kwan; Cho, Jae-Hwan; Lee, Hae-Kag

    2012-10-01

    This study evaluated the gating-based 4-D conformal radiation therapy (4D-CT) treatment planning by a comparison with the common 3-D conformal radiation therapy (3D-CT) treatment planning and examined the change in treatment field size and dose to the tumors and adjacent normal tissues because an unnecessary dose is also included in the 3-D treatment planning for the radiation treatment of tumors in the chest and abdomen. The 3D-CT and gating-based 4D-CT images were obtained from patients who had undergone radiation treatment for chest and abdomen tumors in the oncology department. After establishing a treatment plan, the CT treatment and planning system were used to measure the change in field size for analysis. A dose volume histogram (DVH) was used to calculate the appropriate dose to planning target volume (PTV) tumors and adjacent normal tissue. The difference in the treatment volume of the chest was 0.6 and 0.83 cm on the X- and Y-axis, respectively, for the gross tumor volume (GTV). Accordingly, the values in the 4D-CT treatment planning were smaller and the dose was more concentrated by 2.7% and 0.9% on the GTV and clinical target volume (CTV), respectively. The normal tissues in the surrounding normal tissues were reduced by 3.0%, 7.2%, 0.4%, 1.7%, 2.6% and 0.2% in the bronchus, chest wall, esophagus, heart, lung and spinal cord, respectively. The difference in the treatment volume of the abdomen was 0.72 cm on the X-axis and 0.51 cm on the Y-axis for the GTV; and 1.06 cm on the X-axis and 1.85 cm on the Y-axis for the PTV. Therefore, the values in the 4D-CT treatment planning were smaller. The dose was concentrated by 6.8% and 4.3% on the GTV and PTV, respectively, whereas the adjacent normal tissues in the cord, Lt. kidney, Rt. kidney, small bowels and whole liver were reduced by 3.2%, 4.2%, 1.5%, 6.2% and 12.7%, respectively. The treatment field size was smaller in volume in the case of the 4D-CT treatment planning. In the DVH, the 4D-CT treatment

  10. Effect of Field Size and Length of Plantar Spur on Treatment Outcome in Radiation Therapy of Plantar Fasciitis: The Bigger the Better?

    Energy Technology Data Exchange (ETDEWEB)

    Hermann, Robert Michael, E-mail: hermann@strahlentherapie-westerstede.com [Zentrum für Strahlentherapie und Radioonkologie, Bremen/Westerstede (Germany); Abteilung Strahlentherapie und Spezielle Onkologie, Medizinische Hochschule Hannover (Germany); Meyer, Andreas [Abteilung Strahlentherapie und Spezielle Onkologie, Medizinische Hochschule Hannover (Germany); Gemeinschaftspraxis für Strahlentherapie Hildesheim/Goslar (Germany); Becker, Alexandra [Zentrum für Strahlentherapie und Radioonkologie, Bremen/Westerstede (Germany); Schneider, Michael [Orthopaedic Centre for Musculoskeletal Research, University of Würzburg (Germany); Reible, Michael; Carl, Ulrich Martin [Zentrum für Strahlentherapie und Radioonkologie, Bremen/Westerstede (Germany); Christiansen, Hans [Abteilung Strahlentherapie und Spezielle Onkologie, Medizinische Hochschule Hannover (Germany); Nitsche, Mirko [Zentrum für Strahlentherapie und Radioonkologie, Bremen/Westerstede (Germany); Klinik für Strahlentherapie, Karl-Lennert-Krebscentrum, Universität Kiel (Germany)

    2013-12-01

    Purpose: Radiation therapy is well established in the treatment of painful plantar fasciitis or heel spur. A retrospective analysis was conducted to investigate the effect of field definition on treatment outcome and to determine the impact of factors potentially involved. Methods and Materials: A review of treatment data of 250 patients (285 heels) with a mean follow-up time of 11 months showed that complete symptom remission occurred in 38%, partial remission in 32%, and no change in 19% (11% were lost to follow-up). Variables such as radiologic evidence of plantar spurs, their length, radiation dose, field size, age, sex, and onset of pain before administration of radiation therapy were investigated in univariate and multivariate regression analyses. Results: Treatment response depended upon age >53 years, length of heel spur ≤6.5 mm (or no radiologic evidence of a heel spur), and onset of pain <12 months before radiation therapy. Patients with these clinical prerequisites stood a 93% chance of clinical response. Without these prerequisites, only 49% showed any impact. No influence of field size on treatment outcome became evident. Conclusion: Patients with short plantar heel spurs benefit from radiation therapy equally well as patients without any radiologic evidence. Moreover, smaller field sizes have the same positive effect as commonly used large field definitions covering the entire calcaneal bone. This leads to a recommendation of a considerable reduction of field size in future clinical practice.

  11. Effect of Field Size and Length of Plantar Spur on Treatment Outcome in Radiation Therapy of Plantar Fasciitis: The Bigger the Better?

    International Nuclear Information System (INIS)

    Hermann, Robert Michael; Meyer, Andreas; Becker, Alexandra; Schneider, Michael; Reible, Michael; Carl, Ulrich Martin; Christiansen, Hans; Nitsche, Mirko

    2013-01-01

    Purpose: Radiation therapy is well established in the treatment of painful plantar fasciitis or heel spur. A retrospective analysis was conducted to investigate the effect of field definition on treatment outcome and to determine the impact of factors potentially involved. Methods and Materials: A review of treatment data of 250 patients (285 heels) with a mean follow-up time of 11 months showed that complete symptom remission occurred in 38%, partial remission in 32%, and no change in 19% (11% were lost to follow-up). Variables such as radiologic evidence of plantar spurs, their length, radiation dose, field size, age, sex, and onset of pain before administration of radiation therapy were investigated in univariate and multivariate regression analyses. Results: Treatment response depended upon age >53 years, length of heel spur ≤6.5 mm (or no radiologic evidence of a heel spur), and onset of pain <12 months before radiation therapy. Patients with these clinical prerequisites stood a 93% chance of clinical response. Without these prerequisites, only 49% showed any impact. No influence of field size on treatment outcome became evident. Conclusion: Patients with short plantar heel spurs benefit from radiation therapy equally well as patients without any radiologic evidence. Moreover, smaller field sizes have the same positive effect as commonly used large field definitions covering the entire calcaneal bone. This leads to a recommendation of a considerable reduction of field size in future clinical practice

  12. Analysis of the variation of the attenuation curve in function of the radiation field size for k Vp X-ray beams using the MCNP-5C code

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Marco A.R., E-mail: marco@cetea.com.b, E-mail: marfernandes@fmb.unesp.b [Universidade Estadual Paulista Julio de Mesquita Filho (FMB/UNESP), Botucatu, SP (Brazil). Fac. de Medicina; Ribeiro, Victor A.B. [Universidade Estadual Paulista Julio de Mesquita Filho (IBB/UNESP), Botucatu, SP (Brazil). Inst. de Biociencias; Viana, Rodrigo S.S.; Coelho, Talita S. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The paper illustrates the use of the Monte Carlo method, MCNP-5C code, to analyze the attenuation curve behavior of the 50 kVp radiation beam from superficial radiotherapy equipment as Dermopan2 model. The simulations seek to verify the MCNP-5C code performance to study the variation of the attenuation curve - percentage depth dose (PDD) curve - in function of the radiation field dimension used at radiotherapy of skin tumors with 50 kVp X-ray beams. The PDD curve was calculated for six different radiation field sizes with circular geometry of 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 cm in diameter. The radiation source was modeled considering a tungsten target with inclination 30 deg, focal point of 6.5 mm in diameter and energy beam of 50 kVp; the X-ray spectrum was calculated with the MCNP-5C code adopting total filtration (beryllium window of 1 mm and aluminum additional filter of 1 mm). The PDD showed decreasing behavior with the attenuation depth similar what is presented on the literature. There was not significant variation at the PDD values for the radiation field between 1.0 and 4.0 cm in diameter. The differences increased for fields of 5.0 and 6.0 cm and at attenuation depth higher than 1.0 cm. When it is compared the PDD values for fields of 3.0 and 6.0 cm in diameter, it verifies the greater difference (12.6 %) at depth of 5.7 cm, proving the scattered radiation effect. The MCNP-5C code showed as an appropriate procedure to analyze the attenuation curves of the superficial radiotherapy beams. (author)

  13. Workplace photon radiation fields

    International Nuclear Information System (INIS)

    Burgess, P.H.; Bartlett, D.T.; Ambrosi, P.

    1999-01-01

    The knowledge of workplace radiation fields is essential for measures in radiation protection. Information about the energy and directional distribution of the incident photon radiation was obtained by several devices developed by the National Radiation Protection Board, United Kingdom, by the Statens Stralskyddsinstitut, Sweden, together with EURADOS and by the Physikalisch-Technische Bundesanstalt, Germany. The devices are described and some results obtained at workplaces in nuclear industry, medicine and science in the photon energy range from 20 keV to 7 MeV are given. (author)

  14. Quality of radiation field imaging

    International Nuclear Information System (INIS)

    Petr, I.

    1988-01-01

    The questions were studied of the quality of imaging the gamma radiation field and of the limits of the quality in directional detector scanning. A resolution angle was introduced to quantify the imaging quality, and its relation was sought with the detection effective half-angle of the directional detector. The resolution angle was defined for the simplest configuration of the radiation field consisting of two monoenergetic gamma beams in one plane. It was shown that the resolution angle decreases, i.e., resolution in imaging the radiation field is better, with the effective half-angle of the directional detector. It was also found that resolution of both gamma beams deteriorated when the beams were surrounded with an isotropic background field. If the beams are surrounded with a background field showing general distribution, the angle size will be affected not only by the properties of the detector but also by the distribution of the ambient radiation field and the method of its scanning. The method described can be applied in designing a directional detector necessary for imaging the presumed radiation field in the required quality. (Z.M.). 4 figs., 3 refs

  15. Evaluate existing radiation fields

    International Nuclear Information System (INIS)

    Aldrich, J.M.; Haggard, D.L.; Endres, G.W.R.; Fix, J.J.

    1981-01-01

    Knowledge of the spectrum of energies for beta, gamma, and neutron radiation experienced in the field is crucial to the proper interpretation of personnel dose. Calibration sources and techniques are determined on the basis of their relationship to field exposure. Selected techniques were used to obtain neutron, photon, and beta energy spectra data at several Hanford locations. Four neutron energy spectra and dose measurement methods were used: (1) multisphere spectrometer system; (2) tissue equivalent proportional counter (TEPC); (3) RASCAL (9'' to 3'' sphere ratios); and (4) helium-3 neutron spectrometer. Gamma spectroscopy was done using standard techniques. A specially designed TLD dosimeter was used to obtain beta spectrum measurements. The design and use of each of these instruments is described in the body of this report. Data collected and analyzed for each of the Hanford locations are included

  16. Size effect in radiation damage

    International Nuclear Information System (INIS)

    Brumovsky, M.

    1979-01-01

    Radiation embrittlement of nuclear reactor pressure vessel steels is mostly measured using small standard specimens in dynamic bend tests. Their dimensions are much smaller than those of the reactor. The increase in the critical temperature (transition temperature from the brittle-to-ductile fracture) is normally measured using standard Charpy-V type specimens or small CT-type specimens. This increase is then used as the main parameter for the pressure vessel safety evaluation. The philosophy of experiments is discussed used for the nonirradiated and irradiated pressure vessel steels. A comparison of the increase in the transition temperature measured in different types of specimens using various testing methods (static and dynamic bend tests with notch or crack) is also made. The results of this comparison and another study showed a relatively good agreement. (author)

  17. Nanometer size field effect transistors for terahertz detectors

    International Nuclear Information System (INIS)

    Knap, W; Rumyantsev, S; Coquillat, D; Dyakonova, N; Teppe, F; Vitiello, M S; Tredicucci, A; Blin, S; Shur, M; Nagatsuma, T

    2013-01-01

    Nanometer size field effect transistors can operate as efficient resonant or broadband terahertz detectors, mixers, phase shifters and frequency multipliers at frequencies far beyond their fundamental cut-off frequency. This work is an overview of some recent results concerning the application of nanometer scale field effect transistors for the detection of terahertz radiation. (paper)

  18. Decease of accelerator size for radiation processing

    International Nuclear Information System (INIS)

    Tanaka, Ryuichi; Sunaga, Hiromi

    2003-01-01

    The decrease of accelerator size is an essential means to improve the market competition power of the radiation processing industry and to expand the wide application. Trials for the decrease or minimization are increasing steadily including development of irradiation equipments for exclusive uses. Compact irradiation systems were outlined for the significance and recent examples of the decrease in radiation processing, the problems in the industrial application, and the future of compact accelerators. (author)

  19. Dependence of some transmission factors on field size and treatment depth in external beam radiation therapy (EBRT) using the theratron equinox 100 cobalt 60 machine

    International Nuclear Information System (INIS)

    Odonkor, P.

    2015-07-01

    The use of beam modifiers in today’s radiotherapy is very important as it attenuates the beam and reduces the dose to the patient; therefore the need to know the amount of attenuation (in terms of a transmission factor) they provide during treatment. The purpose of this research work is to evaluate the variation (or dependence) of the transmission factors (TFs) of block tray and physical wedges (of different angles) as a function of treatment depth and field size using both iso-centric setups, SAD and SSD; and thus compare the results from the two setup techniques. Wedge and tray TF measurements were performed in a full scatter, large water phantom using a 0.04cc ionization chamber and an average photon energy of 1.25MV from a cobalt-60 unit at an SAD/SSD of 100cm at various depths and field sizes with gantry and collimator angles fixed at 0°. From the measurements carried out, the wedge TF of the 15°, 30°, 45°, and 60°, wedges were found to be 0.775±0.005, 0.650±0.010, 0.505±0.015, and 0.280±0.015 respectively; and the tray TF was found to be 0.960±0.003. Also, the results obtained showed that both the wedge TF and the tray TF has a strong linear dependence on treatment depth; however, the variation of the 15°, wedge TF and the tray TF with depth is less significant (less than 2%). Maximum percentage variation for the 15°, wedge for the SAD setup was 1.1% and 1.59% for the SSD setup; and that for the tray was 0.60% for the SAD setup and 0.12% for the SSD setup. Also, the variation of the 15°, 30°, and 45°, wedge TF with field size was less significant (less than 2%); and a weaker dependence was observed with field size as compared to the treatment depth. However, the 60°, wedge showed a significant variation (maximum of 2.22% and 2.88% for the SAD and SSD setups respectively) as an increase in field size was accompanied by an increase in its wedge TF. Also though the tray TF graphically showed a strong linear dependence on field size the

  20. Beam size measurement at high radiation levels

    International Nuclear Information System (INIS)

    Decker, F.J.

    1991-05-01

    At the end of the Stanford Linear Accelerator the high energy electron and positron beams are quite small. Beam sizes below 100 μm (σ) as well as the transverse distribution, especially tails, have to be determined. Fluorescent screens observed by TV cameras provide a quick two-dimensional picture, which can be analyzed by digitization. For running the SLAC Linear Collider (SLC) with low backgrounds at the interaction point, collimators are installed at the end of the linac. This causes a high radiation level so that the nearby cameras die within two weeks and so-called ''radiation hard'' cameras within two months. Therefore an optical system has been built, which guides a 5 mm wide picture with a resolution of about 30 μm over a distance of 12 m to an accessible region. The overall resolution is limited by the screen thickness, optical diffraction and the line resolution of the camera. Vibration, chromatic effects or air fluctuations play a much less important role. The pictures are colored to get fast information about the beam current, size and tails. Beside the emittance, more information about the tail size and betatron phase is obtained by using four screens. This will help to develop tail compensation schemes to decrease the emittance growth in the linac at high currents. 4 refs., 2 figs

  1. On the size of sports fields

    International Nuclear Information System (INIS)

    Texier, Baptiste Darbois; Cohen, Caroline; Clanet, Christophe; Dupeux, Guillaume; Quéré, David

    2014-01-01

    The size of sports fields considerably varies from a few meters for table tennis to hundreds of meters for golf. We first show that this size is mainly fixed by the range of the projectile, that is, by the aerodynamic properties of the ball (mass, surface, drag coefficient) and its maximal velocity in the game. This allows us to propose general classifications for sports played with a ball. (paper)

  2. Photometric estimation of defect size in radiation direction

    International Nuclear Information System (INIS)

    Zuev, V.M.

    1993-01-01

    Factors, affecting accuracy of photometric estimation of defect size in radiation transmission direction, are analyzed. Experimentally obtained dependences of contrast of defect image on its size in radiation transmission direction are presented. Practical recommendations on improving accuracy of photometric estimation of defect size in radiation transmission direction, are developed

  3. Macroscopic sizes of field of superrelativistic charges

    International Nuclear Information System (INIS)

    Strel'tsov, V.N.

    1995-01-01

    Based on the equation of Lienard-Wiechert equipotentials, it is shown that the field of superrelativistic charges reaches macroscopic sizes (e.g., R || = 2 m at E e = 50 GeV). This phenomenon serves an initial cause of the known considerable growth of formation length at high energies. 3 refs., 1 tab

  4. Visual verification of linac light and radiation fields coincidence

    International Nuclear Information System (INIS)

    Monti, Angelo F.; Frigerio, Milena; Frigerio, Giovanna

    2003-01-01

    X-ray and light field alignment evaluation is carried out during linac quality assurance programs. In this paper, we compare the size of the light field measured by a photodiode and by a more traditional visual observation with the size of the x-ray field. The comparison between actual light field size, measured with the photodiode, and light field size measured by human eye allow us to verify the reliability of human eye in the evaluation of this parameter. The visual field is always larger than real light field; however, it agrees better with the x-ray field. It matches the light field if we take into account the 25% (± 1%) of the decrement line of the maximum central lightening; however, this method simulates better the actual field employed in radiation treatments

  5. Evaluation of the field size in dental diagnostic radiology system

    International Nuclear Information System (INIS)

    Andrade, P.S.; Potiens, M.P.A.

    2006-01-01

    In this work the field size of a dental X rays machine was evaluated considering the recommendation of the Brazilian Health Ministry Regulation 453 which established basic lines of radiological protection in medical and dental diagnostic radiology. The diameter of the field should not be superior to 6 cm in the localized end point, limiting the radiated area and protecting the head-neck region. The measurements were carried out in a dental X rays machine, Dabi Atlante, model Spectro 70X Seletronic. For the field size or useful beam determination, the intra-oral films were positioned on a plain surface to be exposed in four stages and two focus-film distances (FFD), 20 cm and 27.5 cm: 1) with spacer cone; 2) without spacer cone; 3) with spacer cone and film-holding device; 4) without spacer cone and film-holding device. The results show that the diameter of the field size is satisfactory only for FFD = 20 cm. When the film-holding device is used, which is recommended by the Regulation 453, item 5.8 d(ii), the diameter of the field size exceeds the maximum recommended value of 6 cm. (authors)

  6. Graphene Field Effect Transistor for Radiation Detection

    Science.gov (United States)

    Li, Mary J. (Inventor); Chen, Zhihong (Inventor)

    2016-01-01

    The present invention relates to a graphene field effect transistor-based radiation sensor for use in a variety of radiation detection applications, including manned spaceflight missions. The sensing mechanism of the radiation sensor is based on the high sensitivity of graphene in the local change of electric field that can result from the interaction of ionizing radiation with a gated undoped silicon absorber serving as the supporting substrate in the graphene field effect transistor. The radiation sensor has low power and high sensitivity, a flexible structure, and a wide temperature range, and can be used in a variety of applications, particularly in space missions for human exploration.

  7. Gravitational radiation resistance, radiation damping and field fluctuations

    International Nuclear Information System (INIS)

    Schaefer, G.

    1981-01-01

    Application is made of two different generalised fluctuation-dissipation theorems and their derivations to the calculation of the gravitational quadrupole radiation resistance using the radiation-reaction force given by Misner, Thorne and Wheeler (Gravitation (San Francisco: Freeman) ch 36,37 (1973)) and the usual tidal force on one hand and the tidal force and the free gravitational radiation field on the other hand. The quantum-mechanical version (including thermal generalisations) of the well known classical quadrupole radiation damping formula is obtained as a function of the radiation resistance. (author)

  8. Effects of ionizing radiation and steady magnetic field on erythrocytes

    International Nuclear Information System (INIS)

    Ivanov, S. P.; Galutzov, B. P.; Kuzmanova, M. A.; Markov, M. S.

    1996-01-01

    A complex biophysical test for studying the effects of ionizing and non-ionizing radiation has been developed. The following cell and membrane parameters have been investigated: cell size, cell shape, cell distribution by size, electrophoretic mobility, extent of hemolysis, membrane transport and membrane impedance. Gamma ray doses of 2.2 Gy and 3.3 Gy were used as ionizing radiation and steady (DC) magnetic field of 5-90 mT representing the non-ionizing radiation. Erythrocytes from humans and rats were exposed in vitro to both ionizing and non-ionizing radiation. In some experiments ionizing radiation was applied in vivo as well. Each of the simultaneously studied parameters have been found to change as a function of applied radiation. The proposed test allows an estimation of the changes in the elastic, rheological and electrical parameters of cells and biological membranes. Results indicate that ionizing radiation is significantly more effective in an in vivo application, while magnetic fields are more effective when applied in vitro. Surprisingly, steady magnetic fields were found to act as protector against some harmful effects of ionizing radiation. (authors)

  9. The optimum circular field size for dental radiography with intraoral films

    International Nuclear Information System (INIS)

    van Straaten, F.J.; van Aken, J.

    1982-01-01

    Intraoral radiographs are often made with circular fields to irradiate the film, and in many instances these fields are much larger than the film. The feasibility of reducing a circular radiation field without increasing the probability of excessive cone cutting was evaluated clinically, and an optimum field size was determined. A circular radiation field 4.5 cm. at the tube end was found to minimize cone cutting and reduce the area of tissue irradiated by at least 44 percent. Findings suggest that current I.C.R.P. recommendations for a 6 to 7.5 cm. diameter circular field may be too liberal

  10. Quantization of the Radiation Field

    Indian Academy of Sciences (India)

    field,quantization,Lamb shift. Avinash Khare ... actions as well as for theories beyond like grand unified theories. Further, the same ... cules as well as condensed matter physics, not to men- tion their ... of an electromagnetic field by a moving electron, and of the reaction of this field on the electron have not yet been touched.".

  11. Radiative heat transfer in the extreme near field.

    Science.gov (United States)

    Kim, Kyeongtae; Song, Bai; Fernández-Hurtado, Víctor; Lee, Woochul; Jeong, Wonho; Cui, Longji; Thompson, Dakotah; Feist, Johannes; Reid, M T Homer; García-Vidal, Francisco J; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

    2015-12-17

    Radiative transfer of energy at the nanometre length scale is of great importance to a variety of technologies including heat-assisted magnetic recording, near-field thermophotovoltaics and lithography. Although experimental advances have enabled elucidation of near-field radiative heat transfer in gaps as small as 20-30 nanometres (refs 4-6), quantitative analysis in the extreme near field (less than 10 nanometres) has been greatly limited by experimental challenges. Moreover, the results of pioneering measurements differed from theoretical predictions by orders of magnitude. Here we use custom-fabricated scanning probes with embedded thermocouples, in conjunction with new microdevices capable of periodic temperature modulation, to measure radiative heat transfer down to gaps as small as two nanometres. For our experiments we deposited suitably chosen metal or dielectric layers on the scanning probes and microdevices, enabling direct study of extreme near-field radiation between silica-silica, silicon nitride-silicon nitride and gold-gold surfaces to reveal marked, gap-size-dependent enhancements of radiative heat transfer. Furthermore, our state-of-the-art calculations of radiative heat transfer, performed within the theoretical framework of fluctuational electrodynamics, are in excellent agreement with our experimental results, providing unambiguous evidence that confirms the validity of this theory for modelling radiative heat transfer in gaps as small as a few nanometres. This work lays the foundations required for the rational design of novel technologies that leverage nanoscale radiative heat transfer.

  12. Simulation analysis of radiation fields inside phantoms for neutron irradiation

    International Nuclear Information System (INIS)

    Satoh, Daiki; Takahashi, Fumiaki; Endo, Akira; Ohmachi, Y.; Miyahara, N.

    2007-01-01

    Radiation fields inside phantoms have been calculated for neutron irradiation. Particle and heavy-ion transport code system PHITS was employed for the calculation. Energy and size dependences of neutron dose were analyzed using tissue equivalent spheres of different size. A voxel phantom of mouse was developed based on CT images of an 8-week-old male C3H/HeNs mouse. Deposition energy inside the mouse was calculated for 2- and 10-MeV neutron irradiation. (author)

  13. Study of detectors in beta radiation fields

    International Nuclear Information System (INIS)

    Albuquerque, M. da P.P.; Xavier, M.; Caldas, L.V.E.

    1987-01-01

    Several commercial detectors used with gamma or X radiation are studied. Their sensibility and energetic dependence are analysed in exposures of beta radiation fields. A comparative evaluation with the reference detector (the extrapolation chamber) is presented. (M.A.C.) [pt

  14. Field size and centring for conventional X-ray equipment

    International Nuclear Information System (INIS)

    Klimpel, H.; Kreienfeld, H.; Overbeck, R.

    1989-01-01

    Since 1973, all X-ray equipment for medical applications in the Federal Republic of Germany has had to be examined according to the requirements of the German ''Rontgenverordnung'' before it is used on patients and after each essential modification of design or construction. These examinations are carried out by inspectors appointed by the authorities, e.g. TUV. The field size adjustment and the centring of the radiation beam in relation to the image reception area is checked, along with other tests. To increase quality assurance in X-ray diagnosis, since the mid-1980s X-ray equipment has also been subject to in-service inspections to an increasing extent. (author)

  15. Quality assurance in field radiation measurements

    International Nuclear Information System (INIS)

    Howell, W.P.

    1985-01-01

    In most cases, an ion chamber radiation measuring instrument is calibrated in a uniform gamma radiation field. This results in a uniform ionization field throughout the ion chamber. Measurement conditions encountered in the field often produce non-uniform ionization fields within the ion chamber, making determination of true dose rates to personnel difficult and prone to error. Extensive studies performed at Hanford have provided appropriate correction factors for use with one type of ion chamber instrument, the CP. Suitable corrections are available for the following distinct measurement circumstances: (1) contact measurements on large beta and gamma sources, (2) contact measurements on small beta and gamma sources, (3) contact measurements on small-diameter cylinders, (4) measurements in small gamma beams, and (5) measurements at a distance from large beta sources. Recommendations are made for the implementation of these correction factors, in the interest of improved quality assurance in field radiation measurements. 12 references, 10 figures

  16. Field size and dose distribution of electron beam

    International Nuclear Information System (INIS)

    Kang, Wee Saing

    1980-01-01

    The author concerns some relations between the field size and dose distribution of electron beams. The doses of electron beams are measured by either an ion chamber with an electrometer or by film for dosimetry. We analyzes qualitatively some relations; the energy of incident electron beams and depths of maximum dose, field sizes of electron beams and depth of maximum dose, field size and scatter factor, electron energy and scatter factor, collimator shape and scatter factor, electron energy and surface dose, field size and surface dose, field size and central axis depth dose, and field size and practical range. He meets with some results. They are that the field size of electron beam has influence on the depth of maximum dose, scatter factor, surface dose and central axis depth dose, scatter factor depends on the field size and energy of electron beam, and the shape of the collimator, and the depth of maximum dose and the surface dose depend on the energy of electron beam, but the practical range of electron beam is independent of field size

  17. Local field in finite-size metamaterials

    DEFF Research Database (Denmark)

    Bordo, Vladimir

    2018-01-01

    The theory of the optical response of a metamaterial slab which is represented by metal nanoparticles embedded in a dielectric matrix is developed. It is demonstrated that the account of the reflections from the slab boundaries essentially modifies the local field in the slab and leads...

  18. Size distribution and structure of Barchan dune fields

    Directory of Open Access Journals (Sweden)

    O. Durán

    2011-07-01

    Full Text Available Barchans are isolated mobile dunes often organized in large dune fields. Dune fields seem to present a characteristic dune size and spacing, which suggests a cooperative behavior based on dune interaction. In Duran et al. (2009, we propose that the redistribution of sand by collisions between dunes is a key element for the stability and size selection of barchan dune fields. This approach was based on a mean-field model ignoring the spatial distribution of dune fields. Here, we present a simplified dune field model that includes the spatial evolution of individual dunes as well as their interaction through sand exchange and binary collisions. As a result, the dune field evolves towards a steady state that depends on the boundary conditions. Comparing our results with measurements of Moroccan dune fields, we find that the simulated fields have the same dune size distribution as in real fields but fail to reproduce their homogeneity along the wind direction.

  19. Fiber optics in high dose radiation fields

    International Nuclear Information System (INIS)

    Partin, J.K.

    1985-01-01

    A review of the behavior of state-of-the-art optical fiber waveguides in high dose (greater than or equal to 10 5 rad), steady state radiation fields is presented. The influence on radiation-induced transmission loss due to experimental parameters such as dose rate, total dose, irradiation history, temperature, wavelength, and light intensity, for future work in high dose environments are given

  20. Differential Detector for Measuring Radiation Fields

    International Nuclear Information System (INIS)

    Broide, A.; Marcus, E.; Brandys, I.; Schwartz, A.; Wengrowicz, U.; Levinson, S.; Seif, R.; Sattinger, D.; Kadmon, Y.; Tal, N.

    2004-01-01

    In case of a nuclear accident, it is essential to determine the source of radioactive contamination in order to analyze the risk to the environment and to the population. The radiation source may be a radioactive plume on the air or an area on the ground contaminated with radionuclides. Most commercial radiation detectors measure only the radiation field intensity but are unable to differentiate between the radiation sources. Consequently, this limitation causes a real problem in analyzing the potential risk to the near-by environment, since there is no data concerning the contamination ratios in the air and on the ground and this prevents us from taking the required steps to deal with the radiation event. This work presents a GM-tube-based Differential Detector, which enables to determine the source of contamination

  1. Thyorid function after mantle field radiation therapy

    International Nuclear Information System (INIS)

    Daehnert, W.; Kutzner, J.; Grimm, W.

    1981-01-01

    48 patients with malignant lymphoma received a 60 Co-radiation dose of 30 to 50 Gy using the mantle field technique. Thyroid function tests were performed 34 to 92 months after radiation therapy. One patient developed myxedema, ten (20.8%) had subclinical hypothyroidism and six (12.5%) latent hypothyroidism. The incidence of hypothyroidism after treatment of malignant lymphomas is summarized in a review of the literature. Discrepancies on the incidence of hypothyroidism were found, and their possible cause is discussed. Periodic examinations of all patients with thyroid radiation exposure are recommended. The examination can be limited to measurement of TSH concentration and palpation of the thyroid for nodules. (orig.) [de

  2. Individual Dosimetry for High Energy Radiation Fields

    International Nuclear Information System (INIS)

    Spurny, F.

    1999-01-01

    The exposure of individuals on board aircraft increased interest in individual dosimetry in high energy radiation fields. These fields, both in the case of cosmic rays as primary radiation and at high energy particle accelerators are complex, with a large diversity of particle types, their energies, and linear energy transfer (LET). Several already existing individual dosemeters have been tested in such fields. For the component with high LET (mostly neutrons) etched track detectors were tested with and without fissile radiators, nuclear emulsions, bubble detectors for both types available and an albedo dosemeter. Individual dosimetry for the low LET component has been performed with thermoluminescent detectors (TLDs), photographic film dosemeters and two types of electronic individual dosemeters. It was found that individual dosimetry for the low LET component was satisfactory with the dosemeters tested. As far as the high LET component is concerned, there are problems with both the sensitivity and the energy response. (author)

  3. Radiation distribution sensor with optical fibers for high radiation fields

    International Nuclear Information System (INIS)

    Takada, Eiji; Kimura, Atsushi; Hosono, Yoneichi; Takahashi, Hiroyuki; Nakazawa, Masaharu

    1999-01-01

    Radiation distribution sensors with their feasibilities have been described in earlier works. However, due to large radiation induced transmission losses in optical fibers, especially in the visible wavelength region, it has been difficult to apply these techniques to high radiation fields. In this study, we proposed a new concept of optical fiber based radiation distribution measurements with near infrared (IR) emission. Near IR scintillators were attached to the ends of optical fibers, where the fibers were bundled and connected to an N-MOS line sensor or a cooled CCD camera. From the measurements of each area density, the radiation levels at the positions of the scintillators can be known. The linearity between the gamma dose rate at each scintillator and the registered counts has been examined. For correcting the radiation induced loss effects, we applied the Optical Time Domain Reflectometry technique to measure the loss distribution and from the results, a possibility for correction of the loss effect has been demonstrated. The applicable dose rate range was evaluated to be from 0.1 to 10 3 Gy/h. This system can be a promising tool as a flexible dose rate distribution monitor in radiation facilities like nuclear plants and accelerator facilities. (author)

  4. Radiation Entropy and Near-Field Thermophotovoltaics

    Science.gov (United States)

    Zhang, Zhuomin M.

    2008-08-01

    Radiation entropy was key to the original derivation of Planck's law of blackbody radiation, in 1900. This discovery opened the door to quantum mechanical theory and Planck was awarded the Nobel Prize in Physics in 1918. Thermal radiation plays an important role in incandescent lamps, solar energy utilization, temperature measurements, materials processing, remote sensing for astronomy and space exploration, combustion and furnace design, food processing, cryogenic engineering, as well as numerous agricultural, health, and military applications. While Planck's law has been fruitfully applied to a large number of engineering problems for over 100 years, questions have been raised about its limitation in micro/nano systems, especially at subwavelength distances or in the near field. When two objects are located closer than the characteristic wavelength, wave interference and photon tunneling occurs that can result in significant enhancement of the radiative transfer. Recent studies have shown that the near-field effects can realize emerging technologies, such as superlens, sub-wavelength light source, polariton-assisted nanolithography, thermophotovoltaic (TPV) systems, scanning tunneling thermal microscopy, etc. The concept of entropy has also been applied to explain laser cooling of solids as well as the second law efficiency of devices that utilize thermal radiation to produce electricity. However, little is known as regards the nature of entropy in near-field radiation. Some history and recent advances are reviewed in this presentation with a call for research of radiation entropy in the near field, due to the important applications in the optimization of thermophotovoltaic converters and in the design of practical systems that can harvest photon energies efficiently.

  5. Radiation phase of a dipole field

    International Nuclear Information System (INIS)

    Shunovsky, A.S.

    1998-01-01

    In the case of a dipole electromagnetic radiation, the operator of the 'radiation phase' is defined. It is shown that this operator has a discrete spectrum with eigenvalues, lying in the segment [0,2π]. Some properties of the radiation phase and polarization are discussed. Seventy years of investigation of the problem of quantum phase led to the conclusion that there is no unique quantum variable, determining universally the measured phase properties of electromagnetic radiation. The operator constructions, describing cosine and sine of the phase, could be different schemes of measurement. This fact has accurately been confirmed by a number of recent experiments. Thus, it seems to be quite plausible that the quantum phase properties of an electromagnetic radiation are determined by interaction photons with a macroscopic detecting device. It is pertinent to ask the following question. Are the quantum phase properties of radiation completely determined by such an interaction or the photons have their own inherent phase properties which might be measured even if they are modified by interaction with a detecting device? The universally recognized fact is that the vacuum state of field is degenerated with respect to phase. If a quantum radiation has its inherent phase properties, it means that the degeneration is taken off in the process of generation which is an interaction of the vacuum field with excited states of atoms or molecules. By virtue of this picture proposed in, what all one can expect is that the inherent quantum phase properties of radiation are completely determined by a source via the conservation laws, describing the generation process. Even in this way, it seems to determine a unique quantum phase of radiation. As a matter of fact, there are two conservation laws, admitting a nontrivial angular dependence

  6. Computational methods in several fields of radiation dosimetry

    International Nuclear Information System (INIS)

    Paretzke, Herwig G.

    2010-01-01

    Full text: Radiation dosimetry has to cope with a wide spectrum of applications and requirements in time and size. The ubiquitous presence of various radiation fields or radionuclides in the human home, working, urban or agricultural environment can lead to various dosimetric tasks starting from radioecology, retrospective and predictive dosimetry, personal dosimetry, up to measurements of radionuclide concentrations in environmental and food product and, finally in persons and their excreta. In all these fields measurements and computational models for the interpretation or understanding of observations are employed explicitly or implicitly. In this lecture some examples of own computational models will be given from the various dosimetric fields, including a) Radioecology (e.g. with the code systems based on ECOSYS, which was developed far before the Chernobyl reactor accident, and tested thoroughly afterwards), b) Internal dosimetry (improved metabolism models based on our own data), c) External dosimetry (with the new ICRU-ICRP-Voxelphantom developed by our lab), d) Radiation therapy (with GEANT IV as applied to mixed reactor radiation incident on individualized voxel phantoms), e) Some aspects of nanodosimetric track structure computations (not dealt with in the other presentation of this author). Finally, some general remarks will be made on the high explicit or implicit importance of computational models in radiation protection and other research field dealing with large systems, as well as on good scientific practices which should generally be followed when developing and applying such computational models

  7. Size determination of an equilibrium enzymic system by radiation inactivation

    International Nuclear Information System (INIS)

    Simon, P.; Swillens, S.; Dumont, J.E.

    1982-01-01

    Radiation inactivation of complex enzymic systems is currently used to determine the enzyme size and the molecular organization of the components in the system. An equilibrium model was simulated describing the regulation of enzyme activity by association of the enzyme with a regulatory unit. It is assumed that, after irradiation, the system equilibrates before the enzyme activity is assayed. The theoretical results show that the target-size analysis of these numerical data leads to a bad estimate of the enzyme size. Moreover, some implicit assumptions such as the transfer of radiation energy between non-covalently bound molecules should be verified before interpretation of target-size analysis. It is demonstrated that the apparent target size depends on the parameters of the system, namely the size and the concentration of the components, the equilibrium constant, the relative activities of free enzyme and enzymic complex, the existence of energy transfer, and the distribution of the components between free and bound forms during the irradiation. (author)

  8. Beam size effects in the radiative Bhabha scattering

    International Nuclear Information System (INIS)

    Szczekowski, M.

    1990-01-01

    In some electromagnetic processes the measured cross section can be substantially smaller than calculated in standard Quantum Electrodynamics. The process of single bremsstrahlung, e + e - → e + e - γ is an example of such effect. If the size of the effect for large angle γ radiation is similar to its magnitude at low angles, then standard calculations of the radiative Bahbha background to e.g. the reaction used in counting the number of neutrino generations, e + e - → νν-barγ, at LEP energies can be overestimated by 10-20%. 5 refs., 5 figs. (author)

  9. Electric field engineering using quantum-size-effect-tuned heterojunctions

    KAUST Repository

    Adinolfi, V.; Ning, Z.; Xu, J.; Masala, Silvia; Zhitomirsky, D.; Thon, S. M.; Sargent, E. H.

    2013-01-01

    be tuned across the light-absorbing semiconductor layer via control over CQD size, employing solution-processed, room-temperature fabricated materials. We exploit this feature by designing and demonstrating a field-enhanced heterojunction architecture. We

  10. Recent developments in radiation field control technology

    International Nuclear Information System (INIS)

    Wood, C.J.

    1995-01-01

    The U.S. nuclear power industry has been remarkably successful in reducing worker radiation exposures over the past ten years. There has been over a fourfold reduction in the person-rem incurred for each MW.year of electric power generated: from 1.8 in 1980, to only 0.39 person-rems in 1991 and 1992. Preliminary data for 1993 are even lower: approximately 0.37 person-rem.MW.year. Despite this substantial improvement, challenges for the industry remain. Individual exposure limits have been tightened in ICRP 60 and there will be increased requirements for special maintenance work as plants age, suggesting that vigorous efforts with be increased requirements for special maintenance work as plants age, suggesting that vigorous efforts will be required to meet the industry goals for 1995. Reducing out-of-core radiation fields offer the best chance of continuing the downward trend in exposures. To assist utilities select the most economic technology for their specific plants, EPRI has published a manual capturing worldwide operating experience with radiation-field control techniques (TR-100265). No one method will suffice, but implementing suitable combinations from this collection will enable utilities to achieve their exposure goals. Radiation reduction is generally cost-effective: outages are shorter, manpower requirements are reduced and work quality is improved. Despite the up front costs, the benefits over the following 1-3 years typically outweigh the expenses

  11. Recent developments in radiation field control technology

    Energy Technology Data Exchange (ETDEWEB)

    Wood, C.J. [Electric Power Research Institute, Palo Alto, CA (United States)

    1995-03-01

    The U.S. nuclear power industry has been remarkably successful in reducing worker radiation exposures over the past ten years. There has been over a fourfold reduction in the person-rem incurred for each MW.year of electric power generated: from 1.8 in 1980, to only 0.39 person-rems in 1991 and 1992. Preliminary data for 1993 are even lower: approximately 0.37 person-rem.MW.year. Despite this substantial improvement, challenges for the industry remain. Individual exposure limits have been tightened in ICRP 60 and there will be increased requirements for special maintenance work as plants age, suggesting that vigorous efforts with be increased requirements for special maintenance work as plants age, suggesting that vigorous efforts will be required to meet the industry goals for 1995. Reducing out-of-core radiation fields offer the best chance of continuing the downward trend in exposures. To assist utilities select the most economic technology for their specific plants, EPRI has published a manual capturing worldwide operating experience with radiation-field control techniques (TR-100265). No one method will suffice, but implementing suitable combinations from this collection will enable utilities to achieve their exposure goals. Radiation reduction is generally cost-effective: outages are shorter, manpower requirements are reduced and work quality is improved. Despite the up front costs, the benefits over the following 1-3 years typically outweigh the expenses.

  12. A contemporary decennial global sample of changing agricultural field sizes

    Science.gov (United States)

    White, E.; Roy, D. P.

    2011-12-01

    In the last several hundred years agriculture has caused significant human induced Land Cover Land Use Change (LCLUC) with dramatic cropland expansion and a marked increase in agricultural productivity. The size of agricultural fields is a fundamental description of rural landscapes and provides an insight into the drivers of rural LCLUC. Increasing field sizes cause a subsequent decrease in the number of fields and therefore decreased landscape spatial complexity with impacts on biodiversity, habitat, soil erosion, plant-pollinator interactions, diffusion of disease pathogens and pests, and loss or degradation in buffers to nutrient, herbicide and pesticide flows. In this study, globally distributed locations with significant contemporary field size change were selected guided by a global map of agricultural yield and literature review and were selected to be representative of different driving forces of field size change (associated with technological innovation, socio-economic conditions, government policy, historic patterns of land cover land use, and environmental setting). Seasonal Landsat data acquired on a decadal basis (for 1980, 1990, 2000 and 2010) were used to extract field boundaries and the temporal changes in field size quantified and their causes discussed.

  13. On quantization of the electromagnetic field in radiation gauge

    International Nuclear Information System (INIS)

    Burzynski, A.

    1982-01-01

    This paper contains a detailed description of quantization of the electromagnetic field (in radiation gauge) and quantization of some basic physical variables connected with radiation field as energy, momentum and spin. The dynamics of the free quantum radiation field and the field interacting with external classical sources is described. The canonical formalism is not used explicity. (author)

  14. Haemopoietic cell renewal in radiation fields

    Science.gov (United States)

    Fliedner, T. M.; Nothdurft, W.; Tibken, B.; Hofer, E.; Weiss, M.; Kindler, H.

    1994-10-01

    Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a ``turbulence region'' for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a ``blood stem cell bank'' might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container.

  15. Particles in spherical electromagnetic radiation fields

    International Nuclear Information System (INIS)

    Mitter, H.; Thaller, B.

    1984-03-01

    If the time-dependence of a Hamiltonian can be compensated by an appropriate symmetry transformation, the corresponding quantum mechanical problem can be reduced to an effectively stationary one. With this result we investigate the behavior of nonrelativistic particles in a spherical radiation field produced by a rotating source. Then the symmetry transformation corresponds to a rotation. We calculate the transition probabilities in Born approximation. The extension to problems involving an additional Coulomb potential is briefly discussed. (Author)

  16. Hypofractionated Whole-Breast Radiation Therapy: Does Breast Size Matter?

    Energy Technology Data Exchange (ETDEWEB)

    Hannan, Raquibul, E-mail: Raquibul.Hannan@gmail.com [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas (United States); Thompson, Reid F.; Chen Yu; Bernstein, Karen; Kabarriti, Rafi; Skinner, William [Department of Radiation Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York (United States); Chen, Chin C. [Department of Radiation Oncology, Columbia University Medical Center, New York, New York (United States); Landau, Evan; Miller, Ekeni; Spierer, Marnee; Hong, Linda; Kalnicki, Shalom [Department of Radiation Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York (United States)

    2012-11-15

    Purpose: To evaluate the effects of breast size on dose-volume histogram parameters and clinical toxicity in whole-breast hypofractionated radiation therapy using intensity modulated radiation therapy (IMRT). Materials and Methods: In this retrospective study, all patients undergoing breast-conserving therapy between 2005 and 2009 were screened, and qualifying consecutive patients were included in 1 of 2 cohorts: large-breasted patients (chest wall separation >25 cm or planning target volume [PTV] >1500 cm{sub 3}) (n=97) and small-breasted patients (chest wall separation <25 cm and PTV <1500 cm{sub 3}) (n=32). All patients were treated prone or supine with hypofractionated IMRT to the whole breast (42.4 Gy in 16 fractions) followed by a boost dose (9.6 Gy in 4 fractions). Dosimetric and clinical toxicity data were collected and analyzed using the R statistical package (version 2.12). Results: The mean PTV V95 (percentage of volume receiving >= 95% of prescribed dose) was 90.18% and the mean V105 percentage of volume receiving >= 105% of prescribed dose was 3.55% with no dose greater than 107%. PTV dose was independent of breast size, whereas heart dose and maximum point dose to skin correlated with increasing breast size. Lung dose was markedly decreased in prone compared with supine treatments. Radiation Therapy Oncology Group grade 0, 1, and 2 skin toxicities were noted acutely in 6%, 69%, and 25% of patients, respectively, and at later follow-up (>3 months) in 43%, 57%, and 0% of patients, respectively. Large breast size contributed to increased acute grade 2 toxicity (28% vs 12%, P=.008). Conclusions: Adequate PTV coverage with acceptable hot spots and excellent sparing of organs at risk was achieved by use of IMRT regardless of treatment position and breast size. Although increasing breast size leads to increased heart dose and maximum skin dose, heart dose remained within our institutional constraints and the incidence of overall skin toxicity was comparable

  17. Hypofractionated Whole-Breast Radiation Therapy: Does Breast Size Matter?

    International Nuclear Information System (INIS)

    Hannan, Raquibul; Thompson, Reid F.; Chen Yu; Bernstein, Karen; Kabarriti, Rafi; Skinner, William; Chen, Chin C.; Landau, Evan; Miller, Ekeni; Spierer, Marnee; Hong, Linda; Kalnicki, Shalom

    2012-01-01

    Purpose: To evaluate the effects of breast size on dose-volume histogram parameters and clinical toxicity in whole-breast hypofractionated radiation therapy using intensity modulated radiation therapy (IMRT). Materials and Methods: In this retrospective study, all patients undergoing breast-conserving therapy between 2005 and 2009 were screened, and qualifying consecutive patients were included in 1 of 2 cohorts: large-breasted patients (chest wall separation >25 cm or planning target volume [PTV] >1500 cm 3 ) (n=97) and small-breasted patients (chest wall separation 3 ) (n=32). All patients were treated prone or supine with hypofractionated IMRT to the whole breast (42.4 Gy in 16 fractions) followed by a boost dose (9.6 Gy in 4 fractions). Dosimetric and clinical toxicity data were collected and analyzed using the R statistical package (version 2.12). Results: The mean PTV V95 (percentage of volume receiving >= 95% of prescribed dose) was 90.18% and the mean V105 percentage of volume receiving >= 105% of prescribed dose was 3.55% with no dose greater than 107%. PTV dose was independent of breast size, whereas heart dose and maximum point dose to skin correlated with increasing breast size. Lung dose was markedly decreased in prone compared with supine treatments. Radiation Therapy Oncology Group grade 0, 1, and 2 skin toxicities were noted acutely in 6%, 69%, and 25% of patients, respectively, and at later follow-up (>3 months) in 43%, 57%, and 0% of patients, respectively. Large breast size contributed to increased acute grade 2 toxicity (28% vs 12%, P=.008). Conclusions: Adequate PTV coverage with acceptable hot spots and excellent sparing of organs at risk was achieved by use of IMRT regardless of treatment position and breast size. Although increasing breast size leads to increased heart dose and maximum skin dose, heart dose remained within our institutional constraints and the incidence of overall skin toxicity was comparable to that reported in the

  18. Radiation damage of polymers in ultrasonic fields

    Energy Technology Data Exchange (ETDEWEB)

    Anbalagan, Poornnima

    2008-07-01

    Radiation damage has always been a topic of great interest in various fields of sciences. In this work, an attempt is made to probe into the effect of subthreshold ultrasonic waves on the radiation damage created by irradiation of deuterons in polymer samples wherein the polymer samples act as model systems. Two equal volumes of radiation damage were produced in a single polymer sample wherein a standing wave of ultrasound was introduced into one. Three polymers namely, Polycarbonate, Polymethylmethacrylate and Polyvinyl chloride were used in this work. Four independent techniques were used to analyze the irradiated samples and visualize the radiation damage. Interferometric measurements give a measure of the refractive index modulation in the irradiated sample. Polymers, being transparent, do not absorb in the visible region of the electromagnetic spectrum. UV-Vis absorption spectroscopy shows absorption peaks in the visible region in irradiated polymer samples. Ion irradiation causes coloration of polymers. The light microscope is used to measure the absorption of white light by the irradiated polymers. Positron annihilation spectroscopy is used to obtain a measure of the open volume created by irradiation in polymers. A comparison between the irradiated region and the region exposed to ultrasonic waves simultaneously with irradiation in a polymer sample shows the polymer specific influence of the ultrasonic standing wave. (orig.)

  19. Radiation damage of polymers in ultrasonic fields

    International Nuclear Information System (INIS)

    Anbalagan, Poornnima

    2008-01-01

    Radiation damage has always been a topic of great interest in various fields of sciences. In this work, an attempt is made to probe into the effect of subthreshold ultrasonic waves on the radiation damage created by irradiation of deuterons in polymer samples wherein the polymer samples act as model systems. Two equal volumes of radiation damage were produced in a single polymer sample wherein a standing wave of ultrasound was introduced into one. Three polymers namely, Polycarbonate, Polymethylmethacrylate and Polyvinyl chloride were used in this work. Four independent techniques were used to analyze the irradiated samples and visualize the radiation damage. Interferometric measurements give a measure of the refractive index modulation in the irradiated sample. Polymers, being transparent, do not absorb in the visible region of the electromagnetic spectrum. UV-Vis absorption spectroscopy shows absorption peaks in the visible region in irradiated polymer samples. Ion irradiation causes coloration of polymers. The light microscope is used to measure the absorption of white light by the irradiated polymers. Positron annihilation spectroscopy is used to obtain a measure of the open volume created by irradiation in polymers. A comparison between the irradiated region and the region exposed to ultrasonic waves simultaneously with irradiation in a polymer sample shows the polymer specific influence of the ultrasonic standing wave. (orig.)

  20. Limited-field radiation for bifocal germinoma

    International Nuclear Information System (INIS)

    Lafay-Cousin, Lucie; Millar, Barbara-Ann; Mabbott, Donald; Spiegler, Brenda; Drake, Jim; Bartels, Ute; Huang, Annie; Bouffet, Eric

    2006-01-01

    Purpose: To report the incidence, characteristics, treatment, and outcomes of bifocal germinomas treated with chemotherapy followed by focal radiation. Methods and Materials: This was a retrospective review. Inclusion criteria included radiologic diagnosis of bifocal germinoma involving the pineal and neurohypophyseal region, no evidence of dissemination on spinal MRI, negative results from cerebrospinal fluid cytologic evaluation, and negative tumor markers. Results: Between 1995 and 2004, 6 patients (5 male, 1 female; median age, 12.8 years) fulfilled the inclusion criteria. All had symptoms of diabetes insipidus at presentation. On MRI, 4 patients had a pineal and suprasellar mass, and 2 had a pineal mass associated with abnormal neurohypophyseal enhancement. All patients received chemotherapy followed by limited-field radiation and achieved complete remission after chemotherapy. The radiation field involved the whole ventricular system (range, 2,400-4,000 cGy) with or without a boost to the primary lesions. All patients remain in complete remission at a median follow-up of 48.1 months (range, 9-73.4 months). Conclusions: This experience suggests that bifocal germinoma can be considered a locoregional rather than a metastatic disease. Chemotherapy and focal radiotherapy might be sufficient to provide excellent outcomes. Staging refinement with new diagnostic tools will likely increase the incidence of the entity

  1. Functional size analysis of bioactive materials by radiation inactivation

    International Nuclear Information System (INIS)

    Kume, Tamikazu

    1994-01-01

    When the research on various proteins including enzymes is carried out, first molecular weight is measured. The physical chemical methods used for measuring molecular weight cannot measure it in the state of actually acting in living bodies. Radiation inactivation method is the unique method which can measure the molecular weight of the active substances in living bodies. Paying attention to this point, recently it is attempted to measure the activity unit of enzymes, receptors and others, and to apply to the elucidation of their functions. In this report, the concept of the method of measuring molecular size based on radiation inactivation, the detailed experimental method and the points to which attention must be paid are described. Also its application to the elucidation of living body functions according to the example of the studies by the author is reported. The concept of the measurement of molecular weight by radiation inactivation is based on target theory. The preparation of samples, the effect of oxygen, radiation sources, dosimetry, irradiation temperature, internal standard process and so on are reported. The trend of the research is shown. (K.I.)

  2. Momentum of the Pure Radiation Field

    Directory of Open Access Journals (Sweden)

    Lehnert B.

    2007-01-01

    Full Text Available The local momentum equation of the pure radiation field is considered in terms of an earlier elaborated and revised electromagnetic theory. In this equation the contribution from the volume force is found to vanish in rectangular geometry, and to become nonzero but negligible in cylindrical geometry. Consequently the radiated momentum is due to the Poynting vector only, as in conventional electrodynamics. It results in physically relevant properties of a photon model having an angular momentum (spin. The Poynting vector concept is further compared to the quantized momentum concept for a free particle, as represented by a spatial gradient operator acting on the wave function. However, this latter otherwise successful concept leads to difficulties in the physical interpretation of known and expected photon properties such as the spin, the negligible loss of transverse momentum across a bounding surface, and the Lorentz invariance.

  3. Beam Size Measurement by Optical Diffraction Radiation and Laser System for Compton Polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chuyu [Peking Univ., Beijing (China)

    2012-12-31

    Beam diagnostics is an essential constituent of any accelerator, so that it is named as "organs of sense" or "eyes of the accelerator." Beam diagnostics is a rich field. A great variety of physical effects or physical principles are made use of in this field. Some devices are based on electro-magnetic influence by moving charges, such as faraday cups, beam transformers, pick-ups; Some are related to Coulomb interaction of charged particles with matter, such as scintillators, viewing screens, ionization chambers; Nuclear or elementary particle physics interactions happen in some other devices, like beam loss monitors, polarimeters, luminosity monitors; Some measure photons emitted by moving charges, such as transition radiation, synchrotron radiation monitors and diffraction radiation-which is the topic of the first part of this thesis; Also, some make use of interaction of particles with photons, such as laser wire and Compton polarimeters-which is the second part of my thesis. Diagnostics let us perceive what properties a beam has and how it behaves in a machine, give us guideline for commissioning, controlling the machine and indispensable parameters vital to physics experiments. In the next two decades, the research highlight will be colliders (TESLA, CLIC, JLC) and fourth-generation light sources (TESLA FEL, LCLS, Spring 8 FEL) based on linear accelerator. These machines require a new generation of accelerator with smaller beam, better stability and greater efficiency. Compared with those existing linear accelerators, the performance of next generation linear accelerator will be doubled in all aspects, such as 10 times smaller horizontal beam size, more than 10 times smaller vertical beam size and a few or more times higher peak power. Furthermore, some special positions in the accelerator have even more stringent requirements, such as the interaction point of colliders and wigglor of free electron lasers. Higher performance of these accelerators increases the

  4. Beam Size Measurement by Optical Diffraction Radiation and Laser System for Compton Polarimeter

    International Nuclear Information System (INIS)

    Liu, Chuyu

    2012-01-01

    Beam diagnostics is an essential constituent of any accelerator, so that it is named as 'organs of sense' or 'eyes of the accelerator.' Beam diagnostics is a rich field. A great variety of physical effects or physical principles are made use of in this field. Some devices are based on electro-magnetic influence by moving charges, such as faraday cups, beam transformers, pick-ups; Some are related to Coulomb interaction of charged particles with matter, such as scintillators, viewing screens, ionization chambers; Nuclear or elementary particle physics interactions happen in some other devices, like beam loss monitors, polarimeters, luminosity monitors; Some measure photons emitted by moving charges, such as transition radiation, synchrotron radiation monitors and diffraction radiation-which is the topic of the first part of this thesis; Also, some make use of interaction of particles with photons, such as laser wire and Compton polarimeters-which is the second part of my thesis. Diagnostics let us perceive what properties a beam has and how it behaves in a machine, give us guideline for commissioning, controlling the machine and indispensable parameters vital to physics experiments. In the next two decades, the research highlight will be colliders (TESLA, CLIC, JLC) and fourth-generation light sources (TESLA FEL, LCLS, Spring 8 FEL) based on linear accelerator. These machines require a new generation of accelerator with smaller beam, better stability and greater efficiency. Compared with those existing linear accelerators, the performance of next generation linear accelerator will be doubled in all aspects, such as 10 times smaller horizontal beam size, more than 10 times smaller vertical beam size and a few or more times higher peak power. Furthermore, some special positions in the accelerator have even more stringent requirements, such as the interaction point of colliders and wigglor of free electron lasers. Higher performance of these accelerators increases the

  5. Virtual radiation fields for ALARA determination

    International Nuclear Information System (INIS)

    Knight, T.W.

    1995-01-01

    As computing power has increased, so too has the ability to model and simulate complex systems and processes. In addition, virtual reality technology has made it possible to visualize and understand many complex scientific and engineering problems. For this reason, a virtual dosimetry program called Virtual Radiation Fields (VRF) is developed to model radiation dose rate and cumulative dose to a receptor operating in a virtual radiation environment. With the design and testing of many facilities and products taking place in the virtual world, this program facilitates the concurrent consideration of radiological concerns during the design process. Three-dimensional (3D) graphical presentation of the radiation environment is made possible through the use of IGRIP, a graphical modeling program developed by Deneb Robotics, Inc. The VRF simulation program was designed to model and display a virtual dosimeter. As a demonstration of the program's capability, the Hanford tank, C-106, was modeled to predict radiation doses to robotic equipment used to remove radioactive waste from the tank. To validate VRF dose predictions, comparison was made with reported values for tank C-106, which showed agreement to within 0.5%. Graphical information is presented regarding the 3D dose rate variation inside the tank. Cumulative dose predictions were made for the cleanup operations of tank C-106. A four-dimensional dose rate map generated by VRF was used to model the dose rate not only in 3D space but also as a function of the amount of waste remaining in the tank. This allowed VRF to predict dose rate at any stage in the waste removal process for an accurate simulation of the radiological conditions throughout the tank cleanup procedure

  6. Virtual radiation fields for ALARA determination

    Energy Technology Data Exchange (ETDEWEB)

    Knight, T.W.

    1995-12-31

    As computing power has increased, so too has the ability to model and simulate complex systems and processes. In addition, virtual reality technology has made it possible to visualize and understand many complex scientific and engineering problems. For this reason, a virtual dosimetry program called Virtual Radiation Fields (VRF) is developed to model radiation dose rate and cumulative dose to a receptor operating in a virtual radiation environment. With the design and testing of many facilities and products taking place in the virtual world, this program facilitates the concurrent consideration of radiological concerns during the design process. Three-dimensional (3D) graphical presentation of the radiation environment is made possible through the use of IGRIP, a graphical modeling program developed by Deneb Robotics, Inc. The VRF simulation program was designed to model and display a virtual dosimeter. As a demonstration of the program`s capability, the Hanford tank, C-106, was modeled to predict radiation doses to robotic equipment used to remove radioactive waste from the tank. To validate VRF dose predictions, comparison was made with reported values for tank C-106, which showed agreement to within 0.5%. Graphical information is presented regarding the 3D dose rate variation inside the tank. Cumulative dose predictions were made for the cleanup operations of tank C-106. A four-dimensional dose rate map generated by VRF was used to model the dose rate not only in 3D space but also as a function of the amount of waste remaining in the tank. This allowed VRF to predict dose rate at any stage in the waste removal process for an accurate simulation of the radiological conditions throughout the tank cleanup procedure.

  7. Experimental microdosimetry in high energy radiation fields

    International Nuclear Information System (INIS)

    Spurny, F.; Bednar, J.; Vlcek, B.; Bottollier-Depois, J.-F.; Molokanov, A.G.

    2000-01-01

    To determine microdosimetric characteristics in the beams and fields of high energy panicles with the goal, also, to compare the classical method of experimental microdosimetry, a tissue equivalent low pressure proportional counter (TEPC) with the linear energy transfer (LET) spectrometer based on a chemically etched polyallyldiglycolcarbonate as a track etched detector (TED). To test the use of TED LET spectrometer in the conditions, where the use or TEPC is not possible (high energy charged particle beams at high dose rates). The results obtained with the TEPC NAUSICAA were used in this work to compare them with other data. This TEPC measures directly the linear energy in the interval between 0.15 and 1500 keV/μm in tissue, the low gas pressure (propan based TE mixture) permits to simulate a tissue element of about 3 μm. It can be used in the fields with instantaneous dose equivalent rates between 1 μSv/hour and 1 mSv/ hour. TED LET spectrometer developed to determine LET spectra between 10 and 700 keV/μm in tissue. Primarily, track-to-bulk etch rate ratios are determined through the track parameters measurements, the spectra of these ratios are convened to LET spectra using the calibration curve established by means of heavy charge panicles. The critical volume of thi spectrometer is supposed to be a few nm. There is no limit of use for the dose rate, the background tracks limit the lowest threshold to about 1 mSv, the overlapping of tracks (the highest one) to 100 mSv. Both experimental microdosimetry methods have been used in on board aircraft radiation fields, in on-Earth high energy radiation reference fields, and in the beams of protons with energies up to 300 MeV (Dubna, Moscow, Loma Linda). First, it should be emphasized, that in all high energy radiation fields studied, we concentrated our analysis on the region, where both methods overlap, i.e. between 10 and 1000 keV/μm in tissue. It should be also stressed, that the events observed in this region

  8. Spin and radiation in intense laser fields

    International Nuclear Information System (INIS)

    Walser, M.W.; Urbach, D.J.; Hatsagortsyan, K.Z.; Hu, S.X.; Keitel, C.H.

    2002-01-01

    The spin dynamics and its reaction on the particle motion are investigated for free and bound electrons in intense linearly polarized laser fields. Employing both classical and quantum treatments we analytically evaluate the spin oscillation of free electrons in intense laser fields and indicate the effect of spin-orbit coupling on the motion of the electron. In Mott scattering an estimation for the spin oscillation is derived. In intense laser ion dynamics spin signatures are studied in detail with emphasis on high-order harmonic generation in the tunneling regime. First- and second-order calculations in the ratio of electron velocity and the speed of light show spin signatures in the radiation spectrum and spin-orbit effects in the electron polarization

  9. A micro-controller based palm-size radiation monitor

    International Nuclear Information System (INIS)

    Bhingare, R.R.; Bajaj, K.C.; Kannan, S.

    2001-01-01

    A micro-controller based, palm-size radiation monitor, PALMRAD, using a silicon P-N junction diode as a detector has been developed. It is useful for radiation protection monitoring during radiation emergency as well as radioactive source loading operations. Some of the features of PALMRAD developed are the use of a semiconductor diode as the detector, simultaneous display of integrated dose and dose rate on a 16-digit alpha numeric LCD display, measurable integrated dose range from 1 μSv to 5000 μSv and dose rate range from 1 mSv/h to 1,000 mSv/h, RS 232C serial interface for connection to a Personal Computer,-storage of integrated dose and dose rate readings, recall of stored readings on LCD display, presentable integrated dose alarm from 1 μSv to 5000 μSv and dose rate from 1 mSv/h to 1,000 mSv/h, battery status and memory status check during measurement, LCD display with LED back-lighting, etc. (author)

  10. A method for characterizing photon radiation fields

    International Nuclear Information System (INIS)

    Whicker, J.J.; Hsu, H.H.; Hsieh, F.H.; Borak, T.B.

    1999-01-01

    Uncertainty in dosimetric and exposure rate measurements can increase in areas where multi-directional and low-energy photons (< 100 keV) exist because of variations in energy and angular measurement response. Also, accurate measurement of external exposures in spatially non-uniform fields may require multiple dosimetry. Therefore, knowledge of the photon fields in the workplace is required for full understanding of the accuracy of dosimeters and instruments, and for determining the need for multiple dosimeters. This project was designed to develop methods to characterize photon radiation fields in the workplace, and to test the methods in a plutonium facility. The photon field at selected work locations was characterized using TLDs and a collimated NaI(Tl) detector from which spatial variations in photon energy distributions were calculated from measured spectra. Laboratory results showed the accuracy and utility of the method. Field measurement results combined with observed work patterns suggested the following: (1) workers are exposed from all directions, but not isotropically, (2) photon energy distributions were directionally dependent, (3) stuffing nearby gloves into the glovebox reduced exposure rates significantly, (4) dosimeter placement on the front of the chest provided for a reasonable estimate of the average dose equivalent to workers' torsos, (5) justifiable conclusions regarding the need for multiple dosimetry can be made using this quantitative method, and (6) measurements of the exposure rates with ionization chambers pointed with open beta windows toward the glovebox provided the highest measured rates, although absolute accuracy of the field measurements still needs to be assessed

  11. Temperature field for radiative tomato peeling

    International Nuclear Information System (INIS)

    Cuccurullo, G; Giordano, L

    2017-01-01

    Nowadays peeling of tomatoes is performed by using steam or lye, which are expensive and polluting techniques, thus sustainable alternatives are searched for dry peeling and, among that, radiative heating seems to be a fairly promising method. This paper aims to speed up the prediction of surface temperatures useful for realizing dry-peeling, thus a 1D-analytical model for the unsteady temperature field in a rotating tomato exposed to a radiative heating source is presented. Since only short times are of interest for the problem at hand, the model involves a semi-infinite slab cooled by convective heat transfer while heated by a pulsating heat source. The model being linear, the solution is derived following the Laplace Transform method. A 3D finite element model of the rotating tomato is introduced as well in order to validate the analytical solution. A satisfactory agreement is attained. Therefore, two different ways to predict the onset of the peeling conditions are available which can be of help for proper design of peeling plants. Particular attention is paid to study surface temperature uniformity, that being a critical parameter for realizing an easy tomato peeling. (paper)

  12. The measurement of fringing fields in a radio-frequency hyperthermia array with emphasis on bolus size

    NARCIS (Netherlands)

    Wiersma, J.; van Dijk, J. D.; Sijbrands, J.; Schneider, C. J.

    1998-01-01

    The limited aperture size through which the em-field of the applicator is emanated and the constraining of this em-field near the bolus' edge is related to the appearance of superficial 'hot spot' phenomena in radiative hyperthermia. Regarding systems based on the concept of the annular phased array

  13. Electric field engineering using quantum-size-effect-tuned heterojunctions

    KAUST Repository

    Adinolfi, V.

    2013-07-03

    A quantum junction solar cell architecture was recently reported that employs colloidal quantum dots (CQDs) on each side of the p-n junction. This architecture extends the range of design opportunities for CQD photovoltaics, since the bandgap can be tuned across the light-absorbing semiconductor layer via control over CQD size, employing solution-processed, room-temperature fabricated materials. We exploit this feature by designing and demonstrating a field-enhanced heterojunction architecture. We optimize the electric field profile within the solar cell through bandgap engineering, thereby improving carrier collection and achieving an increased open circuit voltage, resulting in a 12% improvement in power conversion efficiency.

  14. Violin f-hole contribution to far-field radiation via patch near-field acoustical holography.

    Science.gov (United States)

    Bissinger, George; Williams, Earl G; Valdivia, Nicolas

    2007-06-01

    The violin radiates either from dual ports (f-holes) or via surface motion of the corpus (top+ribs+back), with no clear delineation between these sources. Combining "patch" near-field acoustical holography over just the f-hole region of a violin with far-field radiativity measurements over a sphere, it was possible to separate f-hole from surface motion contributions to the total radiation of the corpus below 2.6 kHz. A0, the Helmholtz-like lowest cavity resonance, radiated essentially entirely through the f-holes as expected while A1, the first longitudinal cavity mode with a node at the f-holes, had no significant f-hole radiation. The observed A1 radiation comes from an indirect radiation mechanism, induced corpus motion approximately mirroring the cavity pressure profile seen for violinlike bowed string instruments across a wide range of sizes. The first estimates of the fraction of radiation from the f-holes F(f) indicate that some low frequency corpus modes thought to radiate only via surface motion (notably the first corpus bending modes) had significant radiation through the f-holes, in agreement with net volume changes estimated from experimental modal analysis. F(f) generally trended lower with increasing frequency, following corpus mobility decreases. The f-hole directivity (top/back radiativity ratio) was generally higher than whole-violin directivity.

  15. Radiation field mapping using a mechanical-electronic detector

    Energy Technology Data Exchange (ETDEWEB)

    Czayka, M., E-mail: mczayka@kent.ed [College of Technology, Kent State University-Ashtabula 3300 Lake Road West, Ashtabula, OH 44004 (United States); Program on Electron Beam Technology, Kent State University, P.O. Box 1028, Middlefield, OH 44062 (United States); Fisch, M. [Program on Electron Beam Technology, Kent State University, P.O. Box 1028, Middlefield, OH 44062 (United States); College of Technology, Kent State University, P.O. Box 5190, Kent, OH 44242-0001 (United States)

    2010-04-15

    A method of radiation field mapping of a scanned electron beam using a Faraday-type detector and an electromechanical linear translator is presented. Utilizing this arrangement, fluence and fluence rate measurements can be made at different locations within the radiation field. The Faraday-type detector used in these experiments differs from most as it consists of a hollow stainless steel sphere. Results are presented in two- and three-dimensional views of the radiation field.

  16. Radiation of an electron in an electric field. 1

    International Nuclear Information System (INIS)

    Fedosov, N.I.; Flesher, G.I.

    1976-01-01

    The problem of electron radiation in a field of a travelling electric wave is solved by methods of classical electrodynamics. Such a field may serve as a model of a field on the linear accelerator axis. It is shown that the total radiation power, as well as the spectral-angular distribution of the radiation energy of an electron travelling in a longitudinal electric wave coincide with radiation in a stationary uniform electric field with the strength equal to that of the wave at the point where the particle velocity becomes close to the velocity of light [ru

  17. Vacuum radiation induced by time dependent electric field

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2017-04-01

    Full Text Available Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.

  18. Vacuum radiation induced by time dependent electric field

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bo, E-mail: zhangbolfrc@caep.cn [Department of High Energy Density Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Laboratory of Science and Technology on Plasma Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Zhang, Zhi-meng; Hong, Wei; He, Shu-Kai; Teng, Jian [Department of High Energy Density Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Laboratory of Science and Technology on Plasma Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Gu, Yu-qiu, E-mail: yqgu@caep.cn [Department of High Energy Density Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China); Laboratory of Science and Technology on Plasma Physics, Research Center of Laser Fusion, 621900, Mianyang, Sichuan (China)

    2017-04-10

    Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED) will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.

  19. Radiation, waves, fields. Causes and effects on environment and health

    International Nuclear Information System (INIS)

    Leitgeb, N.

    1990-01-01

    The book discusses static electricity, alternating electric fields, magnetostatic fields, alternating magnetic fields, electromagnetic radiation, optical and ionizing radiation and their hazards and health effects. Each chapter presents basic physical and biological concepts and describes the common radiation sources and their biological effects. Each chapter also contains hints for everyday behaviour as well as in-depth information an specific scientific approaches for assessing biological effects; the latter are addressed to all expert readers working in these fields. There is a special chapter on the problem of so-called 'terrestrial radiation'. (orig.) With 88 figs., 31 tabs [de

  20. Stochastic Neural Field Theory and the System-Size Expansion

    KAUST Repository

    Bressloff, Paul C.

    2010-01-01

    We analyze a master equation formulation of stochastic neurodynamics for a network of synaptically coupled homogeneous neuronal populations each consisting of N identical neurons. The state of the network is specified by the fraction of active or spiking neurons in each population, and transition rates are chosen so that in the thermodynamic or deterministic limit (N → ∞) we recover standard activity-based or voltage-based rate models. We derive the lowest order corrections to these rate equations for large but finite N using two different approximation schemes, one based on the Van Kampen system-size expansion and the other based on path integral methods. Both methods yield the same series expansion of the moment equations, which at O(1/N) can be truncated to form a closed system of equations for the first-and second-order moments. Taking a continuum limit of the moment equations while keeping the system size N fixed generates a system of integrodifferential equations for the mean and covariance of the corresponding stochastic neural field model. We also show how the path integral approach can be used to study large deviation or rare event statistics underlying escape from the basin of attraction of a stable fixed point of the mean-field dynamics; such an analysis is not possible using the system-size expansion since the latter cannot accurately determine exponentially small transitions. © by SIAM.

  1. Field size dependence of wedge factor: miniphantom vs full phantom measurements

    International Nuclear Information System (INIS)

    Allen Li, X.; Szanto, J.; Soubra, M.; Gerig, L. H.

    1995-01-01

    It is empirically known that the transmission factor for wedge in a high-energy photon beam is dependent upon field size and depth of measurement. The field-size dependence of wedge factors may be attributed to changes in (i) head scatter, (ii) phantom scatter, and (iii) backscatter from the wedge into the linac monitor chamber. In this work we present the results of studies designed to examine each of these factors in isolation. The wedge factors for wedges with nominal wedge angles of 15 deg. , 30 deg. , 45 deg. and 60 deg. were measured with a 3-g/cm 2 -diameter narrow cylindrical phantom (miniphantom), a brass cap with 1.5-g/cm 2 side-wall thickness and a full water phantom for 6-, 10- and 18-MV photon beams. The measurements were performed with and without flattening filter in place. The wedge factors measured with the miniphantom and the brass cap exclude the phantom scatter contribution. It has been found that the field-size behaviour of wedge factor measured with full water phantom is similar to that measured with the miniphantom and cap. This indicates that the head scatter radiation is the major contributor to the field size dependence of wedge factors. Wedge factors measured with water phantom are up to 5.0% smaller than those measured with miniphantom. This difference increases with wedge angle. When Measured with the flattening filter removed, the field size dependence of the wedge factor is reduced. This justify that the flattening filter is one of the major contributors to head scatters. The measurement results made with the brass cap agree well with those made by using the miniphantom. By measuring the monitor chamber output, it is found that the backscatters from the wedge into the linac ion chamber have little effect on the field size dependence of the wedge factor

  2. Optical camera system for radiation field

    International Nuclear Information System (INIS)

    Maki, Koichi; Senoo, Makoto; Takahashi, Fuminobu; Shibata, Keiichiro; Honda, Takuro.

    1995-01-01

    An infrared-ray camera comprises a transmitting filter used exclusively for infrared-rays at a specific wavelength, such as far infrared-rays and a lens used exclusively for infrared rays. An infrared ray emitter-incorporated photoelectric image converter comprising an infrared ray emitting device, a focusing lens and a semiconductor image pick-up plate is disposed at a place of low gamma-ray dose rate. Infrared rays emitted from an objective member are passed through the lens system of the camera, and real images are formed by way of the filter. They are transferred by image fibers, introduced to the photoelectric image converter and focused on the image pick-up plate by the image-forming lens. Further, they are converted into electric signals and introduced to a display and monitored. With such a constitution, an optical material used exclusively for infrared rays, for example, ZnSe can be used for the lens system and the optical transmission system. Accordingly, it can be used in a radiation field of high gamma ray dose rate around the periphery of the reactor container. (I.N.)

  3. Six categories of ionizing radiation quantities practical in various fields

    International Nuclear Information System (INIS)

    Zheng Junzheng; Zhuo Weihai

    2011-01-01

    This paper is the part of review on the evolvement of the systems for ionizing radiation quantities and units. In the paper, for better understanding and correct use of the relevant quantities of ionizing radiation, the major ionizing radiation quantities in various fields are divided into six categories. (authors)

  4. On Field Size and Success Probability in Network Coding

    DEFF Research Database (Denmark)

    Geil, Hans Olav; Matsumoto, Ryutaroh; Thomsen, Casper

    2008-01-01

    Using tools from algebraic geometry and Gröbner basis theory we solve two problems in network coding. First we present a method to determine the smallest field size for which linear network coding is feasible. Second we derive improved estimates on the success probability of random linear network...... coding. These estimates take into account which monomials occur in the support of the determinant of the product of Edmonds matrices. Therefore we finally investigate which monomials can occur in the determinant of the Edmonds matrix....

  5. The field size matters: low dose external beam radiotherapy for thumb carpometacarpal osteoarthritis : Importance of field size.

    Science.gov (United States)

    Kaltenborn, Alexander; Bulling, Elke; Nitsche, Mirko; Carl, Ulrich Martin; Hermann, Robert Michael

    2016-08-01

    The purpose of this work was to evaluate the efficacy of low-dose radiotherapy (RT) for thumb carpometacarpal osteoarthritis (rhizarthrosis). The responses of 84 patients (n = 101 joints) were analyzed 3 months after therapy (n = 65) and at 12 months (n = 27). Patients were treated with 6 fractions of 1 Gy, two times a week, with a linear accelerator. At the end of therapy, about 70 % of patients reported a response (partial remission or complete remission), 3 months later about 60 %, and 1 year after treatment 70 %. In univariate regression analysis, higher patient age and field size greater than 6 × 4 cm were associated with response to treatment, while initial increase of pain under treatment was predictive for treatment failure. Duration of RT series (more than 18 days), gender, time of symptoms before RT, stress pain or rest pain, or prior ortheses use, injections, or surgery of the joint were not associated with treatment efficacy. In multivariate regression analysis, only field size and initial pain increase were highly correlated with treatment outcome. In conclusion, RT represents a useful treatment option for patients suffering from carpometacarpal osteoarthritis. In contrast to other benign indications, a larger field size (>6 × 4 cm) seems to be more effective than smaller fields and should be evaluated in further prospective studies.

  6. Study of carbon-doped micro and nano sized alumina for radiation dosimetry applications

    International Nuclear Information System (INIS)

    Fontainha, C. C. P.; Alves, N.; Ferraz, W. B.; Faria, L. O.

    2017-10-01

    New materials have been widely investigated for ionizing radiation dosimetry for medical procedures. Carbon-doped doped alumina (Al 2 O 3 :C) have been proposed as thermoluminescent and photo luminescent dosimeters. In the present study nano and micro-sized alumina doped with different percentages of carbon, sintered under different atmosphere conditions, at temperatures ranging from 1300 to 1750 degrees Celsius, were sintered and their dosimetric characteristics for gamma fields were investigated. Among the investigated sample preparation methods, the micro-sized alumina doped with 0.01% of carbon and sintered at 1700 degrees Celsius under reducing atmosphere has presented the best Tl output, comparable to the best Tl sensitivities ever reported to alumina and better efficiency than the nano-sized alumina synthesized in this study. The influence of humidity in the Tl signal has been evaluated to be -4.0%. The micro-sized alumina obtained by the methodology used in this work is a suitable candidate for application in X and gamma radiation dosimetry. (Author)

  7. Adiabatic compression and radiative compression of magnetic fields

    International Nuclear Information System (INIS)

    Woods, C.H.

    1980-01-01

    Flux is conserved during mechanical compression of magnetic fields for both nonrelativistic and relativistic compressors. However, the relativistic compressor generates radiation, which can carry up to twice the energy content of the magnetic field compressed adiabatically. The radiation may be either confined or allowed to escape

  8. Electromagnetic field, excited by monodirected X-radiation pulse

    International Nuclear Information System (INIS)

    Zhemerov, A.V.; Metelkin, E.V.

    1994-01-01

    Parameters of electromagnetic field, generated in the atmosphere by monodirected pulse source of X radiation located at the altitude of approximately several kilometers have been estimated by the method of delayed potentials. The source radiation is directed towards the Earth surface. The conclusion was made that restricted areas of approximately 1 km with considerable pulse electromagnetic fields can be created on the Earth surface

  9. Radiative decay of coupled states in an external dc field

    International Nuclear Information System (INIS)

    Pal'chikov, V.; Sokolov, Y.; Yakovlev, V.

    2001-01-01

    This paper examines two theoretical aspects of the interference of atomic states in hydrogen which comes from the application of an external electric field F to the 2s metastable state. The radiative corrections to the Bethe-Lamb formula and anisotropy contribution to the angular distribution, which arises from interference between electric-field-induced E1-radiation and forbidden M1-radiation, are analysed

  10. Radiative decay of coupled states in an external dc field

    Energy Technology Data Exchange (ETDEWEB)

    Pal' chikov, V. [National Research Inst. for Physical-Technical and Radiotechnical Measurements (VNIIFTRI), Mendeleevo, Moscow Region (Russian Federation); Sokolov, Y. [Kurchatov Inst., Russian Research Centre, Moscow (Russian Federation); Yakovlev, V. [Moscow Engineering Physics Inst., Moscow (Russian Federation)

    2001-07-01

    This paper examines two theoretical aspects of the interference of atomic states in hydrogen which comes from the application of an external electric field F to the 2s metastable state. The radiative corrections to the Bethe-Lamb formula and anisotropy contribution to the angular distribution, which arises from interference between electric-field-induced E1-radiation and forbidden M1-radiation, are analysed.

  11. Recent developments in the field of radiation processing

    International Nuclear Information System (INIS)

    Andrzej, G. Chmielewski

    2006-01-01

    Full text: Radiation has been discovered more than one hundred years ago. Since than, properties of radiation to modify physico-chemical properties of materials have found many applications. Radiation technologies applying gamma sources and electron accelerators for material processing are well established processes. There are over 160 gamma industrial irradiators and 1300 electron industrial accelerators in operation worldwide. They are being widely used for sterilization, food irradiation and polymer processing. New developments in the field of radiation sources engineering are compact size gamma irradiators, high power electron accelerators (medium energy range) for environmental applications and other types (high energy range) for materials' processing, with direct e-/X conversion. Future applications of low energy, inexpensive EB processing systems are foreseen. Electron beam lithography for microelectronics is a well-established technique. The already tested e-/X system equipped in an accelerator of 700 kW power opens new horizons for this kind of application. The developments described above need introduction of new computational methods that facilitate prediction of dose distribution, even in containers filled with complex products of varying densities. This technique provides good solutions for homeland security applications which may be complemented by mobile system applications. Technologies to be developed besides environmental applications could be nano materials, structure engineered materials (sorbents, the composites, ordered polymers, etc.) and natural polymers' processing. New products based on radiation processed polysaccharides have already been commercialized in many countries of the East Asia and Pacific Region, especially in those being rich in natural polymers. Very important and promising applications concern environment protection - radiation technology being a clean and environment friendly process, helps to curb pollutants' emission as

  12. Molecular sizes of lichen ice nucleation sites determined by gamma radiation inactivation analysis

    International Nuclear Information System (INIS)

    Kieft, T.L.; Ruscetti, T.

    1992-01-01

    It has previously been shown that some species of lichen fungi contain proteinaceous ice nuclei which are active at temperatures as warm as −2 °C. This experiment was undertaken to determine the molecular sizes of ice nuclei in the lichen fungus Rhizoplaca chrysoleuca and to compare them to bacterial ice nuclei from Pseudomonas syringae. Gamma radiation inactivation analysis was used to determine molecular weights. Radiation inactivation analysis is based on target theory, which states that the likelihood of a molecule being inactivated by gamma rays increases as its size increases. Three different sources of ice nuclei from the lichen R. chrysoleuca were tested: field-collected lichens, extract of lichen fungus, and a pure culture of the fungus R. chrysoleuca. P. syringae strain Cit7 was used as a source of bacterial ice nuclei. Samples were lyophilized, irradiated with gamma doses ranging from 0 to 10.4 Mrads, and then tested for ice nucleation activity using a droplet-freezing assay. Data for all four types of samples were in rough agreement; sizes of nucleation sites increased logarithmically with increasing temperatures of ice nucleation activity. Molecular weights of nucleation sites active between −3 and −4 °C from the bacteria and from the field-collected lichens were approximately 1.0 × 10 6 Da. Nuclei from the lichen fungus and in the lichen extract appeared to be slightly smaller but followed the same log-normal pattern with temperature of ice nucleation activity. The data for both the bacterial and lichen ice nuclei are in agreement with ice nucleation theory which states that the size of ice nucleation sites increases logarithmically as the temperature of nucleation increases linearly. This suggests that although some differences exist between bacterial and lichen ice nucleation sites, their molecular sizes are quite similar

  13. Review of radiation sources, calibration facilities and simulated workplace fields

    Energy Technology Data Exchange (ETDEWEB)

    Lacoste, V., E-mail: veronique.lacoste@irsn.f [Institut de Radioprotection et de Surete Nucleaire, BP3, Bat. 159, F-13115 Saint-Paul Lez Durance (France)

    2010-12-15

    A review on radiation sources, calibration facilities and realistic fields is presented and examples are given. The main characteristics of the fields are shortly described together with their domain of applications. New emerging fields are also mentioned and the question of needs for additional calibration fields is raised.

  14. Irradiation test of component for radiation-resistant small sized motor

    International Nuclear Information System (INIS)

    Nakamichi, M.; Ishitsuka, E.; Shimakawa, S.; Kan, S.

    2009-01-01

    A small-sized motor with a resistance to radiation was developed. This motor has been able to operate at a gamma-ray dose of a value 700 times as high as the specification of a commercial motor. The present work describes results of post-irradiation examinations (PIEs) to evaluate effects of neutron irradiation on the lifetime of some major components of the motor such as a bearing, a magnet and a fixation agent for a field coil wire. It became clear from the results of PIEs that the radiation-resistance dose of the motor using a Sm-Co magnet will be expected to be one order of magnitude higher than that of the motor using a Nb-Fe-B magnet.

  15. Development of Object Simulator for Radiation Field of Dental X-Rays

    International Nuclear Information System (INIS)

    Silva, L F; Ferreira, F C L; Sousa, F F; Cardoso, L X; Vasconcelos, E D S; Brasil, L M

    2013-01-01

    In dentistry radiography is of fundamental importance to the dentist can make an accurate diagnosis. For this it is necessary to pay attention to the radiological protection of both the professional and the patient and control image quality for an accurate diagnosis. In this work, quality control tests were performed on X-ray machines in private dental intraoral in the municipality of Marabá, where they measured the diameters of the radiation field to see if these machines are in accordance with the recommendations, thus preventing the patient is exposed to a radiation field higher than necessary. We will study the results of each X-ray machine evaluated. For this we created a phantom to assess the size of the radiation field of X-ray dental, where we measure the radiation field of each device to see if they are in accordance with the recommendations of the ordinance No. 453/98 – MS

  16. Combined equations for estimating global solar radiation: Projection of radiation field over Japan under global warming conditions by statistical downscaling

    International Nuclear Information System (INIS)

    Iizumi, T.; Nishimori, M.; Yokozawa, M.

    2008-01-01

    For this study, we developed a new statistical model to estimate the daily accumulated global solar radiation on the earth's surface and used the model to generate a high-resolution climate change scenario of the radiation field in Japan. The statistical model mainly relies on precipitable water vapor calculated from air temperature and relative humidity on the surface to estimate seasonal changes in global solar radiation. On the other hand, to estimate daily radiation fluctuations, the model uses either a diurnal temperature range or relative humidity. The diurnal temperature range, calculated from the daily maximum and minimum temperatures, and relative humidity is a general output of most climate models, and pertinent observation data are comparatively easy to access. The statistical model performed well when estimating the monthly mean value, daily fluctuation statistics, and regional differences in the radiation field in Japan. To project the change in the radiation field for the years 2081 to 2100, we applied the statistical model to the climate change scenario of a high-resolution Regional Climate Model with a 20-km mesh size (RCM20) developed at the Meteorological Research Institute based on the Special Report for Emission Scenario (SRES)-A2. The projected change shows the following tendency: global solar radiation will increase in the warm season and decrease in the cool season in many areas of Japan, indicating that global warming may cause changes in the radiation field in Japan. The generated climate change scenario for the radiation field is linked to long-term and short-term changes in air temperature and relative humidity obtained from the RCM20 and, consequently, is expected to complement the RCM20 datasets for an impact assessment study in the agricultural sector

  17. Underwater inspection training in intense radiation field

    International Nuclear Information System (INIS)

    Taniguchi, Ryoichi

    2017-01-01

    Osaka Prefecture University has a large dose cobalt 60 gamma ray source of about 2 PBq, and is engaged in technological training and human resource development. It is assumed that the decommissioning underwater operation of Fukushima Daiichi Nuclear Power Station would be the focus. The university aims at acquisition of the basic of underwater inspection work under radiation environment that is useful for the above purpose, radiation measurement under water, basic training in image measurement, and aims as well to evaluate the damage of imaging equipment due to radiation, and master practical knowledge for the use of inspection equipment under a large dose. In particular, it is valuable to train in the observation of Cherenkov light emitted from a large dose cobalt radiation source in water using a high sensitivity camera. The measurement of radiation dose distribution in water had difficulty in remote measurement due to water shielding effect. Although it took much time before, the method using high sensitivity camera is easy to sequentially perform two-dimensional measurement, and its utility value is large. Its effect on the dose distribution measurement of irregularly shaped sources is great. The contents of training includes the following: radiation source imaging in water, use of a laser rangefinder in water, dose distribution measurement in water and Cherenkov light measurement, judgment of equipment damage due to irradiation, weak radiation measurement, and measurement and decontamination of surface contamination. (A.O.)

  18. Radiation Pressure Measurements on Micron-Size Individual Dust Grains

    Science.gov (United States)

    Abbas, M. M.; Craven, P. D.; Spann, J. F.; Witherow, W. K.; West, E. A.; Gallagher, D. L.; Adrian, M. L.; Fishman, G. J.; Tankosic, D.; LeClair, A.

    2003-01-01

    Measurements of electromagnetic radiation pressure have been made on individual silica (SiO2) particles levitated in an electrodynamic balance. These measurements were made by inserting single charged particles of known diameter in the 0.2- to 6.82-micron range and irradiating them from above with laser radiation focused to beam widths of approximately 175- 400 microns at ambient pressures particle due to the radiation force is balanced by the electrostatic force indicated by the compensating dc potential applied to the balance electrodes, providing a direct measure of the radiation force on the levitated particle. Theoretical calculations of the radiation pressure with a least-squares fit to the measured data yield the radiation pressure efficiencies of the particles, and comparisons with Mie scattering theory calculations provide the imaginary part of the refractive index of SiO2 and the corresponding extinction and scattering efficiencies.

  19. Rounded leaf end effect of multileaf collimator on penumbra width and radiation field offset: an analytical and numerical study

    International Nuclear Information System (INIS)

    Zhou, Dong; Zhang, Hui; Ye, Peiqing

    2015-01-01

    Penumbra characteristics play a significant role in dose delivery accuracy for radiation therapy. For treatment planning, penumbra width and radiation field offset strongly influence target dose conformity and organ at risk sparing. In this study, we present an analytical and numerical approach for evaluation of the rounded leaf end effect on penumbra characteristics. Based on the rule of half-value layer, algorithms for leaf position calculation and radiation field offset correction were developed, which were advantageous particularly in dealing with large radius leaf end. Computer simulation was performed based on the Monte Carlo codes of EGSnrc/BEAMnrc, with groups of leaf end radii and source sizes. Data processing technique of curve fitting was employed for deriving penumbra width and radiation field offset. Results showed that penumbra width increased with source size. Penumbra width curves for large radius leaf end were U-shaped. This observation was probably related to the fact that radiation beams penetrated through the proximal and distal leaf sides. In contrast, source size had negligible impact on radiation field offset. Radiation field offsets were found to be constant both for analytical method and numerical simulation. However, the overall resulting values of radiation field offset obtained by analytical method were slightly smaller compared with Monte Carlo simulation. The method we proposed could provide insight into the investigation of rounded leaf end effects on penumbra characteristics. Penumbra width and radiation field offset calibration should be carefully performed to commission multileaf collimator for intensity modulated radiotherapy

  20. Size and field effect on mesoscopic spin glass

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, K. [Department of Applied Physics and Physico-Infomatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan)]. E-mail: komatsu@az.appi.keio.ac.jp; Maki, H. [Department of Applied Physics and Physico-Infomatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan); Taniyama, T. [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Sato, T. [Department of Applied Physics and Physico-Infomatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522 (Japan)

    2007-03-15

    Spin glass particles were prepared as the mesoscopic system in order to examine the space scale of spin glass domain (droplet). The peak temperature T {sub peak} in the temperature-dependent magnetization is systematically reduced with decreasing average particle size. This is due to the imitation of droplet growth to the particle diameter. The magnetic field H also decreases T {sub peak}, which is caused by the reduction of the barrier height by Zeeman energy. However, there appears different tendency in the relation between H and T {sub peak} below 100 Oe. This indicates the existence of crossover between the two regimes in which the free energy and Zeeman energy govern the droplet excitation.

  1. Radiation breeding researches in gamma field. Results of researches

    International Nuclear Information System (INIS)

    Morishita, Toshikazu

    2006-01-01

    Abstract of radiation breeding researches and outline of gamma field in IRB (Institute of Radiation Breeding) are described. The gamma field is a circular field of 100 m radius with 88.8TBqCo-60 source at the center. The field is surrounded by a shielding dike of 8 m in height. The effects of gamma irradiation on the growing plants, mutant by gamma radiation and plant molecular biological researches using mutant varieties obtained by the gamma field are explained. For examples, Japanese pear, chrysanthemum, Cytisus, Eustoma grandiflorum, Manila grass, tea and rose are reported. The mutant varieties in the gamma field, nine mutant varieties of flower colors in chrysanthemum, evergreen mutant lines in Manila grass, selection of self-compatible mutants in tea plant, and the plants of the gamma field recently are shown. (S.Y.)

  2. Separation of radiation from two sources from their known radiated sum field

    DEFF Research Database (Denmark)

    Laitinen, Tommi; Pivnenko, Sergey

    2011-01-01

    This paper presents a technique for complete and exact separation of the radiated fields of two sources (at the same frequency) from the knowledge of their radiated sum field. The two sources can be arbitrary but it must be possible to enclose the sources inside their own non-intersecting minimum...

  3. Radiation Pressure Measurements on Micron Size Individual Dust Grains

    Science.gov (United States)

    Abbas, M. M.; Craven, P.D.; Spann, J. F.; Tankosic, D.; Witherow, W. K.; LeClair, A.; West, E.; Sheldon, R.; Gallagher, D. L.; Adrian, M. L.

    2003-01-01

    Measurements of electromagnetic radiation pressure have been made on individual silica (SiO2) particles levitated in an electrodynamic balance. These measurements were made by inserting single charged particles of known diameter in the 0.2 micron to 6.82 micron range and irradiating them from above with laser radiation focused to beam-widths of approx. 175-400 micron, at ambient pressures approx. 10(exp -3) to 10(exp -4) torr. The downward displacement of the particle due to the radiation force is balanced by the electrostatic force indicated by the compensating dc potential applied to the balance electrodes, providing a direct measure of the radiation force on the levitated particle. Theoretical calculations of the radiation pressure with a least-squares fit to the measured data yield the radiation pressure efficiencies of the particles, and comparisons with Mie scattering theory calculations provide the imaginary part of the refractive index of silica and the corresponding extinction and scattering efficiencies.

  4. Effect of field size on the reaction of pig skin to single doses of X rays

    Energy Technology Data Exchange (ETDEWEB)

    Hopewell, J W; Young, C M.A. [Churchill Hospital, Oxford (UK)

    1982-05-01

    The importance of the size of the treatment area for the response of the skin to radiation has been studied in the pig. The responses of skin areas of 16 cm/sup 2/ (4 x 4 cm) and 64cm/sup 2/ (16 x 4 cm) were compared after single doses of X rays. In the initial 3-9-week period after irradiation the severity of the erythema reaction, which is associated with epidermal cell death, was not influenced by the area of skin irradiated. For the later dermal response (10-16 weeks) a similar result was obtained. The dose required to produce dermal necrosis in 50% of the fields treated (ED/sub 50/) was approximately 2070 cGy for both field sizes. Additional studies have shown that the ED/sub 50/ for dermal necrosis was not influenced by the age of animals at the time of irradiation. This was despite considerable differences in the vascular density and blood flow in pig skin with increasing age. The apparent contradiction between the results of this experimental study in the pig, which shows no effect of field size, and currently accepted clinical practice is discussed.

  5. The Electromagnetic Dipole Radiation Field through the Hamiltonian Approach

    Science.gov (United States)

    Likar, A.; Razpet, N.

    2009-01-01

    The dipole radiation from an oscillating charge is treated using the Hamiltonian approach to electrodynamics where the concept of cavity modes plays a central role. We show that the calculation of the radiation field can be obtained in a closed form within this approach by emphasizing the role of coherence between the cavity modes, which is…

  6. Radiation from channeled positrons in a hypersonic wave field

    International Nuclear Information System (INIS)

    Mkrtchyan, A.R.; Gasparyan, R.A.; Gabrielyan, R.G.

    1987-01-01

    The radiation emitted by channeled positrons in a longitudinal or transverse standing hypersonic wave field is considered. In the case of plane channeling the spectral distribution of the radiation intensity is shown to be of a resonance nature depending on the hypersound frequency

  7. Conditions's considerations of the CT radiation field

    International Nuclear Information System (INIS)

    Andrade, Lucio das Chagas de; Peixoto, Jose Guilherme Pereira

    2013-01-01

    In obtaining the standardization of radiation fields in diagnostic radiology were established standards and qualities to X radiation beams, which are specified in terms of the tension in the tube, first CSR, additional filters, homogeneity coefficient or second CSR. The qualities recommended in CT (RQT), are established in IEC 61267, which is the reference for the establishment of beams in diagnostic radiology. (author)

  8. Hawking radiation of a vector field and gravitational anomalies

    International Nuclear Information System (INIS)

    Murata, Keiju; Miyamoto, Umpei

    2007-01-01

    Recently, the relation between Hawking radiation and gravitational anomalies has been used to estimate the flux of Hawking radiation for a large class of black objects. In this paper, we extend the formalism, originally proposed by Robinson and Wilczek, to the Hawking radiation of vector particles (photons). It is explicitly shown, with the Hamiltonian formalism, that the theory of an electromagnetic field on d-dimensional spherical black holes reduces to one of an infinite number of massive complex scalar fields on 2-dimensional spacetime, for which the usual anomaly-cancellation method is available. It is found that the total energy emitted from the horizon for the electromagnetic field is just (d-2) times that for a scalar field. The results support the picture that Hawking radiation can be regarded as an anomaly eliminator on horizons. Possible extensions and applications of the analysis are discussed

  9. Tomography of binomial states of the radiation field

    NARCIS (Netherlands)

    Bazrafkan, MR; Man'ko, [No Value

    2004-01-01

    The symplectic, optical, and photon-number tomographic symbols of binomial states of the radiation field are studied. Explicit relations for all tomograms of the binomial states are obtained. Two measures for nonclassical properties of these states are discussed.

  10. International cooperation in the field of radiation application

    International Nuclear Information System (INIS)

    Sato, Shoichi

    1993-01-01

    Bilateral and multilateral research cooperations have been implemented at TRCRE, JAERI, producing favourable results in the field of radiation application. Frameworks and some achievements are described and the significance of the international cooperation is discussed. (Author)

  11. Online virtual isocenter based radiation field targeting for high performance small animal microirradiation

    Science.gov (United States)

    Stewart, James M. P.; Ansell, Steve; Lindsay, Patricia E.; Jaffray, David A.

    2015-12-01

    Advances in precision microirradiators for small animal radiation oncology studies have provided the framework for novel translational radiobiological studies. Such systems target radiation fields at the scale required for small animal investigations, typically through a combination of on-board computed tomography image guidance and fixed, interchangeable collimators. Robust targeting accuracy of these radiation fields remains challenging, particularly at the millimetre scale field sizes achievable by the majority of microirradiators. Consistent and reproducible targeting accuracy is further hindered as collimators are removed and inserted during a typical experimental workflow. This investigation quantified this targeting uncertainty and developed an online method based on a virtual treatment isocenter to actively ensure high performance targeting accuracy for all radiation field sizes. The results indicated that the two-dimensional field placement uncertainty was as high as 1.16 mm at isocenter, with simulations suggesting this error could be reduced to 0.20 mm using the online correction method. End-to-end targeting analysis of a ball bearing target on radiochromic film sections showed an improved targeting accuracy with the three-dimensional vector targeting error across six different collimators reduced from 0.56+/- 0.05 mm (mean  ±  SD) to 0.05+/- 0.05 mm for an isotropic imaging voxel size of 0.1 mm.

  12. Effects of hypersonic field and anharmonic interactions on channelling radiation

    International Nuclear Information System (INIS)

    George, Juby; Pathak, Anand P; Goteti, L N S Prakash; Nagamani, G

    2007-01-01

    The effects of a hypersonic field on positron channelling radiation are considered. Anharmonic effects of the transverse potential induced by these longitudinal fields are incorporated and the wavefunction of the planar channelled positron is found by the solution of Dirac equation under the resonant influence of hypersound. An expression for the resonant frequency is estimated. The transition probabilities and the intensity of the channelling radiation are also calculated. It is found that the anharmonic effects change the spectral distributions considerably

  13. Maximal near-field radiative heat transfer between two plates

    OpenAIRE

    Nefzaoui, Elyes; Ezzahri, Younès; Drevillon, Jérémie; Joulain, Karl

    2013-01-01

    International audience; Near-field radiative transfer is a promising way to significantly and simultaneously enhance both thermo-photovoltaic (TPV) devices power densities and efficiencies. A parametric study of Drude and Lorentz models performances in maximizing near-field radiative heat transfer between two semi-infinite planes separated by nanometric distances at room temperature is presented in this paper. Optimal parameters of these models that provide optical properties maximizing the r...

  14. Field study to evaluate radiation doses in dental practices

    International Nuclear Information System (INIS)

    Panzer, W.; Scheurer, C.

    1984-05-01

    An inexpensive and simple test device was developed and used in a field study to evaluate entrance dose, dose to an intra-oral film, filtration and field size under routine conditions in more than 150 dental practices. The test device consists of two films of different speed and a set of 5 thin copper filters for a filter analytical determination of the radiation quality. Dentists voluntarily participating in the study were asked to expose the test device like they usually do when examining a molar tooth. The main result was the evidence of a significant dose reduction compared to the findings of similar studies performed in 1970 and 1976. This reduction is due to a general shift to lower values and a complete disappearance of values above 45 mGy (5 R) which in 1970 were still more than 15%. In the same way the number of facilities showing insufficient filtration or collimation had decreased. Nevertheless, a large spread of dose values could still be observed, ranging from less than 0.45 mGy (50 mR) to more than 26 mGy (3 R), for the entrance dose. The most striking result, however, was that such an important parameter like the speed of the films used at the respective unit turned out to have no impact on the entrance dose. (orig./HP)

  15. Behavior of MOSFET Amplifier in Radiation Fields

    International Nuclear Information System (INIS)

    Sharshar, K.A.A.; Ashry, M.

    2000-01-01

    MOSFET type 2 N 3823 characteristics and its application as an amplifier are analyzed including the effects of gamma, electron beam 1.5 MeV 25 m A and neutron flux. The 1-V characteristics, transfer curve, and the frequency response of the amplifier, and the amplification factor(A v 0 are discussed with MOSFET circuit parameters. The drain current and the amplitude of the output signal decrease as the absorbed dose increases. The measured values of the amplified signal are attenuated by 30% and 6% after exposing the MOSFET to gamma radiation and electron beam at the same dose respectively. Also for exposure to 4x10 13 N/cm 3 neutrons decreased the measured value of the amplified signal by 73% of the initial values. The decrease in the gain of the MOSFET is due to the degradation of the transconductance. It is also noticed that percentage of the decrease depends on the type of radiation

  16. Irradiation tests of a small-sized motor with radiation resistance

    International Nuclear Information System (INIS)

    Nakamichi, M.; Ishitsuka, E.; Shimakawa, S.; Kan, S.

    2007-01-01

    In the Test Blanket Module (TBM) of the International Thermonuclear Experimental Reactor (ITER), tritium production and release behavior will be studied using neutrons from fusion reactions, as the blanket development for a demonstration (DEMO) reactor. For development of the TBM, in-pile functional tests are planned, including an integrated irradiation experiment of a fusion blanket mock-up for pulsed operation simulating the ITER operation mode, using the Japan Materials Testing Reactor (JMTR) of Japan Atomic Energy Agency (JAEA).Due to be installed in an irradiation rig, a small-sized motor has to be developed for rotating a neutron absorber with a window to realize the simulated pulse operation. Since degradation of materials of the motor may be caused by radiation damage due to neutron and gamma-ray irradiation, it is important to examine the soundness of the motor materials under the neutron and gamma irradiation.In the present study, a small-sized motor with increased radiation resistance was developed as follows. A design of a commercial alternate current (AC) servomotor was adopted in the base structure, and some components of the motor were replaced by those made of radiation-proof materials, through elimination of organic materials. Polyester-coated wire for field coil and epoxy for fixed resin were replaced by polyimide-coated wire and polysiloxane filled with MgO and Al 2 O 3 , respectively. Furthermore, inorganic lubricant (Mo-based coating of 4 micro meter in thickness) was treated on the surface of a gear, instead of organic (polyphenylether) oil.Radiation-induced degradation of the components of the developed small-sized motor was examined using JMTR and the Japan Research Reactor No.4 (JRR-4) of JAEA. The motor was operating normally up to a gamma-ray dose of 7 x 10 8 Gy, a fast neutron (E>1 MeV) fluence of 2 x 10 21 m -2 and a thermal neutron (E 22 m -2 . The irradiated gamma-ray dose for this motor is about 700 times as high as the operation

  17. Light extinction method for diagnostics of particles sizes formed in magnetic field

    Science.gov (United States)

    Myshkin, Vyacheslav; Izhoykin, Dmitry; Grigoriev, Alexander; Gamov, Denis; Leonteva, Daria

    2018-03-01

    The results of laser diagnostics of dispersed particles formed upon cooling of Zn vapor are presented. The radiation attenuation in the wavelength range 420-630 nm with a step of 0.3 nm was registered. The attenuation coefficients spectral dependence was processed using known algorithms for integral equation solving. The 10 groups of 8 attenuation coefficients were formed. Each group was processed taking with considering of previous decisions. After processing of the 10th group of data, calculations were repeated from the first one. Data of the particles sizes formed in a magnetic field of 0, 44 and 76 mT are given. A model of physical processes in a magnetic field is discussed.

  18. Development of advanced radiation monitors for pulsed neutron fields

    CERN Document Server

    AUTHOR|(CDS)2081895

    The need of radiation detectors capable of efficiently measuring in pulsed neutron fields is attracting widespread interest since the 60s. The efforts of the scientific community substantially increased in the last decade due to the increasing number of applications in which this radiation field is encountered. This is a major issue especially at particle accelerator facilities, where pulsed neutron fields are present because of beam losses at targets, collimators and beam dumps, and where the correct assessment of the intensity of the neutron fields is fundamental for radiation protection monitoring. LUPIN is a neutron detector that combines an innovative acquisition electronics based on logarithmic amplification of the collected current signal and a special technique used to derive the total number of detected neutron interactions, which has been specifically conceived to work in pulsed neutron fields. Due to its special working principle, it is capable of overcoming the typical saturation issues encountere...

  19. Lightweight space radiator with leakage control by internal electrostatic fields

    International Nuclear Information System (INIS)

    Kim, H.; Bankoff, S.G.; Miksis, M.J.

    1991-01-01

    An electrostatic liquid film space radiator is proposed. This will employ an internal electrostatic field to prevent leakage of the liquid-metal coolant out of a puncture. This overcomes the major disadvantage of membrane radiators, which is their vulnerability to micrometeorite impacts. Calculations show that leaks of liquid lithium at 700 degree K can easily be stopped from punctures which are several mm in diameter, with very large safety factors. The basic idea lends itself to a variety of radiator concepts, both rotating and non-rotating. Some typical film thickness and pressure calculations in the presence of an electric field are shown

  20. Establishment of 137Cs radiation fields for instrument calibration

    International Nuclear Information System (INIS)

    Albuquerque, M. da P.P.; Caldas, L.V.E.; Xavier, M.

    1988-09-01

    In order to study the energy dependence of clinical dosemeters, systems constituted of ionization chambers connected to special electrometers, many times their calibration with the gamma radiation of 137 Cs is necessary. In this case, the radiation field characterization is fundamental. The source used presents and activity of 38,8 Tbq and belongs to the Calibration Laboratory of IPEN. Dosimetric films, gammagraphy films, ionization chambers and Lucite phantons were used. At the calibration distance, 80 cm (detector-source detection), the homogeneity of a 10 X 10 cm 2 radiation field was equal 68%. (author) [pt

  1. Radiation effects on relativistic electrons in strong external fields

    International Nuclear Information System (INIS)

    Iqbal, Khalid

    2013-01-01

    The effects of radiation of high energy electron beams are a major issue in almost all types of charged particle accelerators. The objective of this thesis is both the analytical and numerical study of radiation effects. Due to its many applications the study of the self force has become a very active and productive field of research. The main part of this thesis is devoted to the study of radiation effects in laser-based plasma accelerators. Analytical models predict the existence of radiation effects. The investigation of radiation reaction show that in laser-based plasma accelerators, the self force effects lower the energy gain and emittance for moderate energies electron beams and increase the relative energy spread. However, for relatively high energy electron beams, the self radiation and retardation (radiation effects of one electron on the other electron of the system) effects increase the transverse emittance of the beam. The energy gain decreases to even lower value and relative energy spread increases to even higher value due to high radiation losses. The second part of this thesis investigates with radiation reaction in focused laser beams. Radiation effects are very weak even for high energy electrons. The radiation-free acceleration and the simple practical setup make direct acceleration in a focused laser beam very attractive. The results presented in this thesis can be helpful for the optimization of future electron acceleration experiments, in particular in the case of laser-plasma accelerators.

  2. Effect of field size on determination of mean free path of a magnetized mortar irradiated with energy photons between 65 and 1250 keV

    International Nuclear Information System (INIS)

    Andrade, M. Paes de; Vieira, J.W.; Filho, Joao Antonio

    2011-01-01

    The size effect of the radiation field in determining the half value layer (HVL) and the relaxation length of a magnetized mortar was evaluated for photon beams of energy between 65 and 1250 keV. The mortar consists of water, cement, limonite and magnetite has been shaped and constructed a computer simulation of photon beam attenuation for different radiation fields with diameters between 3 and 20 cm using the Monte Carlo code Penelope. For the same energy and different sizes of the radiation field, the ratio of HVL and μx showed a deviation of up to 21% when the radiation beam was attenuated 99%. It was concluded that the experimental determination of the magnitudes of the HVL and μx for the mortar and the irradiation conditions used in this study were made with narrow radiation fields. (author)

  3. Gravitational radiation from preheating with many fields

    International Nuclear Information System (INIS)

    Jr, John T. Giblin; Price, Larry R.; Siemens, Xavier

    2010-01-01

    Parametric resonances provide a mechanism by which particles can be created just after inflation. Thus far, attention has focused on a single or many inflaton fields coupled to a single scalar field. However, generically we expect the inflaton to couple to many other relativistic degrees of freedom present in the early universe. Using simulations in an expanding Friedmann-Lemaître-Robertson-Walker spacetime, in this paper we show how preheating is affected by the addition of multiple fields coupled to the inflaton. We focus our attention on gravitational wave production — an important potential observational signature of the preheating stage. We find that preheating and its gravitational wave signature is robust to the coupling of the inflaton to more matter fields

  4. Gravitational radiation from preheating with many fields

    Energy Technology Data Exchange (ETDEWEB)

    Jr, John T. Giblin [Department of Physics, Kenyon College, 201 North College Road, Gambier, OH 43022 (United States); Price, Larry R.; Siemens, Xavier, E-mail: giblinj@kenyon.edu, E-mail: larry@gravity.phys.uwm.edu, E-mail: siemens@gravity.phys.uwm.edu [Center for Gravitation and Cosmology, Department of Physics, University of Wisconsin — Milwaukee, P.O. Box 413, Milwaukee, WI 53201 (United States)

    2010-08-01

    Parametric resonances provide a mechanism by which particles can be created just after inflation. Thus far, attention has focused on a single or many inflaton fields coupled to a single scalar field. However, generically we expect the inflaton to couple to many other relativistic degrees of freedom present in the early universe. Using simulations in an expanding Friedmann-Lemaître-Robertson-Walker spacetime, in this paper we show how preheating is affected by the addition of multiple fields coupled to the inflaton. We focus our attention on gravitational wave production — an important potential observational signature of the preheating stage. We find that preheating and its gravitational wave signature is robust to the coupling of the inflaton to more matter fields.

  5. Relationship between x-ray illumination field size and flat field intensity and its impacts on x-ray imaging

    International Nuclear Information System (INIS)

    Dong Xue; Niu Tianye; Jia Xun; Zhu Lei

    2012-01-01

    Purpose: X-ray cone-beam CT (CBCT) is being increasingly used for various clinical applications, while its performance is still hindered by image artifacts. This work investigates a new source of reconstruction error, which is often overlooked in the current CBCT imaging. The authors find that the x-ray flat field intensity (I 0 ) varies significantly as the illumination volume size changes at different collimator settings. A wrong I 0 value leads to inaccurate CT numbers of reconstructed images as well as wrong scatter measurements in the CBCT research. Methods: The authors argue that the finite size of x-ray focal spot together with the detector glare effect cause the I 0 variation at different illumination sizes. Although the focal spot of commercial x-ray tubes typically has a nominal size of less than 1 mm, the off-focal-spot radiation covers an area of several millimeters on the tungsten target. Due to the large magnification factor from the field collimator to the detector, the penumbra effects of the collimator blades result in different I 0 values for different illumination field sizes. Detector glare further increases the variation, since one pencil beam of incident x-ray is scattered into an area of several centimeters on the detector. In this paper, the authors study these two effects by measuring the focal spot distribution with a pinhole assembly and the detector point spread function (PSF) with an edge-spread function method. The authors then derive a formula to estimate the I 0 value for different illumination field sizes, using the measured focal spot distribution and the detector PSF. Phantom studies are carried out to investigate the accuracy of scatter measurements and CT images with and without considering the I 0 variation effects. Results: On our tabletop system with a Varian Paxscan 4030CB flat-panel detector and a Varian RAD-94 x-ray tube as used on a clinical CBCT system, the focal spot distribution has a measured full

  6. Membrane-bound Na,K-ATPase: target size and radiation inactivation size of some of its enzymatic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, J.; Norby, J.G.

    1988-12-05

    Frozen samples of membrane-bound pig kidney Na,K-ATPase were subjected to target size analysis by radiation inactivation with 10-MeV electrons at -15 degrees C. The various properties investigated decreased monoexponentially with radiation dose, and the decay constants, gamma, were independent of the presence of other proteins and of sucrose concentrations above 0.25 M. The temperature factor was the same as described by others. Irradiation of four proteins of known molecular mass, m, showed that gamma for protein integrity was proportional to m with a proportionality factor about 20% higher than that conventionally used. By this standard curve, glucose-6-phosphate dehydrogenase activity used as internal standard gave a radiation inactivation size of 110 +/- 5 kDa, very close to m = 104-108 kDa for the dimer, as expected. For Na+/K+-transporting ATPase the following target sizes and radiation inactivation size values were very close to m = 112 kDa for the alpha-peptide: peptide integrity of alpha, 115 kDa; unmodified binding sites for ATP and vanadate, 108 kDa; K+-activated p-nitrophenylphosphatase activity, 106 kDa. There was thus no sign of dimerization of the alpha-peptide or involvement of the beta-peptide. In contrast, optimal Na+/K+-transporting ATPase activity had a radiation inactivation size = 189 +/- 7 kDa, and total nucleotide binding capacity corresponded to 72 +/- 3 kDa. These latter results will be extended and discussed in a forthcoming paper.

  7. Membrane-bound Na,K-ATPase: target size and radiation inactivation size of some of its enzymatic reactions

    International Nuclear Information System (INIS)

    Jensen, J.; Norby, J.G.

    1988-01-01

    Frozen samples of membrane-bound pig kidney Na,K-ATPase were subjected to target size analysis by radiation inactivation with 10-MeV electrons at -15 degrees C. The various properties investigated decreased monoexponentially with radiation dose, and the decay constants, gamma, were independent of the presence of other proteins and of sucrose concentrations above 0.25 M. The temperature factor was the same as described by others. Irradiation of four proteins of known molecular mass, m, showed that gamma for protein integrity was proportional to m with a proportionality factor about 20% higher than that conventionally used. By this standard curve, glucose-6-phosphate dehydrogenase activity used as internal standard gave a radiation inactivation size of 110 +/- 5 kDa, very close to m = 104-108 kDa for the dimer, as expected. For Na+/K+-transporting ATPase the following target sizes and radiation inactivation size values were very close to m = 112 kDa for the alpha-peptide: peptide integrity of alpha, 115 kDa; unmodified binding sites for ATP and vanadate, 108 kDa; K+-activated p-nitrophenylphosphatase activity, 106 kDa. There was thus no sign of dimerization of the alpha-peptide or involvement of the beta-peptide. In contrast, optimal Na+/K+-transporting ATPase activity had a radiation inactivation size = 189 +/- 7 kDa, and total nucleotide binding capacity corresponded to 72 +/- 3 kDa. These latter results will be extended and discussed in a forthcoming paper

  8. A practical and theoretical definition of very small field size for radiotherapy output factor measurements.

    Science.gov (United States)

    Charles, P H; Cranmer-Sargison, G; Thwaites, D I; Crowe, S B; Kairn, T; Knight, R T; Kenny, J; Langton, C M; Trapp, J V

    2014-04-01

    This work introduces the concept of very small field size. Output factor (OPF) measurements at these field sizes require extremely careful experimental methodology including the measurement of dosimetric field size at the same time as each OPF measurement. Two quantifiable scientific definitions of the threshold of very small field size are presented. A practical definition was established by quantifying the effect that a 1 mm error in field size or detector position had on OPFs and setting acceptable uncertainties on OPF at 1%. Alternatively, for a theoretical definition of very small field size, the OPFs were separated into additional factors to investigate the specific effects of lateral electronic disequilibrium, photon scatter in the phantom, and source occlusion. The dominant effect was established and formed the basis of a theoretical definition of very small fields. Each factor was obtained using Monte Carlo simulations of a Varian iX linear accelerator for various square field sizes of side length from 4 to 100 mm, using a nominal photon energy of 6 MV. According to the practical definition established in this project, field sizes ≤ 15 mm were considered to be very small for 6 MV beams for maximal field size uncertainties of 1 mm. If the acceptable uncertainty in the OPF was increased from 1.0% to 2.0%, or field size uncertainties are 0.5 mm, field sizes ≤ 12 mm were considered to be very small. Lateral electronic disequilibrium in the phantom was the dominant cause of change in OPF at very small field sizes. Thus the theoretical definition of very small field size coincided to the field size at which lateral electronic disequilibrium clearly caused a greater change in OPF than any other effects. This was found to occur at field sizes ≤ 12 mm. Source occlusion also caused a large change in OPF for field sizes ≤ 8 mm. Based on the results of this study, field sizes ≤ 12 mm were considered to be theoretically very small for 6 MV beams. Extremely

  9. Black-body radiation of noncommutative gauge fields

    International Nuclear Information System (INIS)

    Fatollahi, Amir H.; Hajirahimi, Maryam

    2006-01-01

    The black-body radiation is considered in a theory with noncommutative electRomegnetic fields; that is noncommutativity is introduced in field space, rather than in real space. A direct implication of the result on cosmic microwave background map is argued

  10. Sound power radiated by sources in diffuse fields

    DEFF Research Database (Denmark)

    Polack, Jean-Dominique

    2000-01-01

    Sound power radiated by sources at low frequency notoriously depends on source position. We sampled the sound field of a rectangular room at 18 microphone and 4 source positions. Average power spectra were extrapolated from the reverberant field, taking into account the frequency dependent...

  11. Spherical-wave expansions of piston-radiator fields.

    Science.gov (United States)

    Wittmann, R C; Yaghjian, A D

    1991-09-01

    Simple spherical-wave expansions of the continuous-wave fields of a circular piston radiator in a rigid baffle are derived. These expansions are valid throughout the illuminated half-space and are useful for efficient numerical computation in the near-field region. Multipole coefficients are given by closed-form expressions which can be evaluated recursively.

  12. Problems with ink skin markings for radiation field setups

    International Nuclear Information System (INIS)

    Endoh, Masaru; Saeki, Mituaki; Ishida, Yusei

    1982-01-01

    Ink skin markings are used in radiation therapy to aid in reproduction of treatment field setups or to indelibly outline field markings or tumors. We reported two cases of indelible ink skin for radiation field septa with minimal discomfort and dermatitis have been experienced for 6 months and above since end of radiotherapy. These indelible ink skin markings look like tattoo that will be big problems in the case of young female. We improved these problems by using of 10 percent silver nitrate instead of habitual skin ink. (author)

  13. Matter and Radiation in Strong Magnetic Fields of Neutron Stars

    International Nuclear Information System (INIS)

    Lai, D

    2006-01-01

    Neutron stars are found to possess magnetic fields ranging from 10 8 G to 10 15 G, much larger than achievable in terrestrial laboratories. Understanding the properties of matter and radiative transfer in strong magnetic fields is essential for the proper interpretation of various observations of magnetic neutron stars, including radio pulsars and magnetars. This paper reviews the atomic/molecular physics and condensed matter physics in strong magnetic fields, as well as recent works on modeling radiation from magnetized neutron star atmospheres/surface layers

  14. Subdiffraction field localisation in the scattering of femtosecond laser radiation by a dielectric microsphere

    Energy Technology Data Exchange (ETDEWEB)

    Geints, Yu E; Zemlyanov, A A; Panina, E K [V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (Russian Federation)

    2014-01-31

    The time dynamics of the optical field was theoretically considered in the near-field diffraction zone in the scattering of a femtosecond laser pulse by a transparent spherical microparticle. The spatial region of field focusing by the particle (the 'photonic jet' zone) was investigated; the evolution of the jet shape and the peak intensity in this region were analysed. For the first time it was determined that an extremely tight optical field localisation to a subdiffraction size is possible at a certain (resonance) temporal stage of photonic jet development. (radiation scattering)

  15. Optimizing CT radiation dose based on patient size and image quality: the size-specific dose estimate method

    Energy Technology Data Exchange (ETDEWEB)

    Larson, David B. [Stanford University School of Medicine, Department of Radiology, Stanford, CA (United States)

    2014-10-15

    The principle of ALARA (dose as low as reasonably achievable) calls for dose optimization rather than dose reduction, per se. Optimization of CT radiation dose is accomplished by producing images of acceptable diagnostic image quality using the lowest dose method available. Because it is image quality that constrains the dose, CT dose optimization is primarily a problem of image quality rather than radiation dose. Therefore, the primary focus in CT radiation dose optimization should be on image quality. However, no reliable direct measure of image quality has been developed for routine clinical practice. Until such measures become available, size-specific dose estimates (SSDE) can be used as a reasonable image-quality estimate. The SSDE method of radiation dose optimization for CT abdomen and pelvis consists of plotting SSDE for a sample of examinations as a function of patient size, establishing an SSDE threshold curve based on radiologists' assessment of image quality, and modifying protocols to consistently produce doses that are slightly above the threshold SSDE curve. Challenges in operationalizing CT radiation dose optimization include data gathering and monitoring, managing the complexities of the numerous protocols, scanners and operators, and understanding the relationship of the automated tube current modulation (ATCM) parameters to image quality. Because CT manufacturers currently maintain their ATCM algorithms as secret for proprietary reasons, prospective modeling of SSDE for patient populations is not possible without reverse engineering the ATCM algorithm and, hence, optimization by this method requires a trial-and-error approach. (orig.)

  16. Near-field characteristics of radiating-wave simulator antenna based on TEM horn

    International Nuclear Information System (INIS)

    Tian Chunming; Ge Debiao

    2004-01-01

    This paper presents a novel antenna of NEMP (nuclear electromagnetic pulse) radiating-wave simulator, which is analyzed and optimized using the finite-difference time domain (FDTD) method. The intense voltage pulse is fed as the source to this antenna by the coaxial line. The parallel plate transmission line and the size of the transverse electromagnetic horn are optimized. The near field of antenna is analyzed, and the effects of the size on the near field are also given. The antenna designed in this paper can well satisfy the requirement for studying the EMP effects

  17. WE-EF-BRA-08: Cell Survival in Modulated Radiation Fields and Altered DNA-Repair at Field Edges

    Energy Technology Data Exchange (ETDEWEB)

    Bartzsch, S; Oelfke, U [The Institute of Cancer Research, London (United Kingdom); Eismann, S [University of Heidelberg, Heidelberg, DE (Germany)

    2015-06-15

    Purpose: Tissue damage prognoses in radiotherapy are based on clonogenic assays that provide dose dependent cell survival rates. However, recent work has shown that apart from dose, systemic reactions and cell-cell communication crucially influence the radiation response. These effects are probably a key in understanding treatment approaches such as microbeam radiation therapy (MRT). In this study we tried to quantify the effects on a cellular level in spatially modulated radiation fields. Methods: Pancreas carcinoma cells were cultured, plated and irradiated by spatially modulated radiation fields with an X-ray tube and at a synchrotron. During and after treatment cells were able to communicate via the intercellular medium. Afterwards we stained for DNA and DNA damage and imaged with a fluorescence microscope. Results: Intriguingly we found that DNA damage does not strictly increase with dose. Two cell entities appear that have either a high or a low amount of DNA lesions, indicating that DNA damage is also a cell stress reaction. Close to radiation boundaries damage-levels became alike; they were higher than expected at low and lower than expected at high doses. Neighbouring cells reacted similarly. 6 hours after exposure around 40% of the cells resembled in their reactions neighbouring cells more than randomly chosen cells that received the same dose. We also observed that close to radiation boundaries the radiation induced cell-cycle arrest disappeared and the size of DNA repair-centres increased. Conclusion: Cell communication plays an important role in the radiation response of tissues and may be both, protective and destructive. These effects may not only have the potential to affect conventional radiotherapy but may also be exploited to spare organs at risk by intelligently designing irradiation geometries. To that end intensive work is required to shed light on the still obscure processes in cell-signalling and radiation biology.

  18. A proposal how to take into account inhomogeneous radiation fields in radiation protection

    International Nuclear Information System (INIS)

    Tschurlovits, M.

    1996-01-01

    External radiation fields exposing the human body inhomogenously are not considered neither in radiation protection standards nor in recent ICRU recommendations, but appear frequently in practical radiation protection. A proposal to solve this question is given taking into account both a conceptual and a metrological approach. The proposal suggests that a mean over an area of about 100 cm 2 can be taken as reference area for compliance with limits in terms of effective dose. (author)

  19. Super-Planckian far-field radiative heat transfer

    Science.gov (United States)

    Fernández-Hurtado, V.; Fernández-Domínguez, A. I.; Feist, J.; García-Vidal, F. J.; Cuevas, J. C.

    2018-01-01

    We present here a theoretical analysis that demonstrates that the far-field radiative heat transfer between objects with dimensions smaller than the thermal wavelength can overcome the Planckian limit by orders of magnitude. To guide the search for super-Planckian far-field radiative heat transfer, we make use of the theory of fluctuational electrodynamics and derive a relation between the far-field radiative heat transfer and the directional absorption efficiency of the objects involved. Guided by this relation, and making use of state-of-the-art numerical simulations, we show that the far-field radiative heat transfer between highly anisotropic objects can largely overcome the black-body limit when some of their dimensions are smaller than the thermal wavelength. In particular, we illustrate this phenomenon in the case of suspended pads made of polar dielectrics like SiN or SiO2. These structures are widely used to measure the thermal transport through nanowires and low-dimensional systems and can be employed to test our predictions. Our work illustrates the dramatic failure of the classical theory to predict the far-field radiative heat transfer between micro- and nanodevices.

  20. IAEA programme in the field of radiation technology

    International Nuclear Information System (INIS)

    Chmielewski, Andrzej G.; Haji-Saeid, Mohammad

    2005-01-01

    Radiation technologies applying gamma sources and electron accelerators for material modification are well-established processes. There are over 160 gamma industrial irradiators and 1300 electron industrial accelerators in operation worldwide. A new advancement in the field of radiation sources engineering is the development of high power direct e - /X conversion sources based on electron accelerators. Technologies to be developed beside environmental applications could be nanomaterials, structure engineered materials (sorbents, composites, ordered polymers, etc.) and natural polymers' processing. New products based on radiation-processed polysaccharides have already been commercialised in many countries of the East Asia and Pacific Region, especially in those being rich in natural polymers. Very important and promising applications concern environmental protection-radiation technology, being a clean and environment friendly process, helps to curb pollutants' emission as well. Industrial plants for flue gas treatment have been constructed in Poland and China. The pilot plant in Bulgaria using this technology has just started its operation. The Polish plant is equipped with accelerators of over 1 MW power, a breakthrough in radiation technology application. The industrial plant for wastewater treatment is under development in Korea and a pilot plant for sewage sludge irradiation has been in operation in India for many years. Due to recent developments, the Agency has restructured its programme and organized a Technical Meeting (TM) on 'Emerging Applications of Radiation Technology for the 21st Century' at its Headquarters in Vienna, Austria, in April 2003, to review the present situation and possible developments of radiation technology to contribute to a sustainable development. This meeting provided the basic input to launch others in the most important fields of radiation technology applications: 'Advances in Radiation Chemistry of Polymers' (Notre Dame, USA

  1. IAEA programme in the field of radiation technology

    Science.gov (United States)

    Chmielewski, Andrzej G.; Haji-Saeid, Mohammad

    2005-07-01

    Radiation technologies applying gamma sources and electron accelerators for material modification are well-established processes. There are over 160 gamma industrial irradiators and 1300 electron industrial accelerators in operation worldwide. A new advancement in the field of radiation sources engineering is the development of high power direct e-/X conversion sources based on electron accelerators. Technologies to be developed beside environmental applications could be nanomaterials, structure engineered materials (sorbents, composites, ordered polymers, etc.) and natural polymers' processing. New products based on radiation-processed polysaccharides have already been commercialised in many countries of the East Asia and Pacific Region, especially in those being rich in natural polymers. Very important and promising applications concern environmental protection-radiation technology, being a clean and environment friendly process, helps to curb pollutants' emission as well. Industrial plants for flue gas treatment have been constructed in Poland and China. The pilot plant in Bulgaria using this technology has just started its operation. The Polish plant is equipped with accelerators of over 1 MW power, a breakthrough in radiation technology application. The industrial plant for wastewater treatment is under development in Korea and a pilot plant for sewage sludge irradiation has been in operation in India for many years. Due to recent developments, the Agency has restructured its programme and organized a Technical Meeting (TM) on "Emerging Applications of Radiation Technology for the 21st Century" at its Headquarters in Vienna, Austria, in April 2003, to review the present situation and possible developments of radiation technology to contribute to a sustainable development. This meeting provided the basic input to launch others in the most important fields of radiation technology applications: "Advances in Radiation Chemistry of Polymers" (Notre Dame, USA

  2. Near-field radiative heat transfer in mesoporous alumina

    International Nuclear Information System (INIS)

    Li Jing; Feng Yan-Hui; Zhang Xin-Xin; Huang Cong-Liang; Wang Ge

    2015-01-01

    The thermal conductivity of mesoporous material has aroused the great interest of scholars due to its wide applications such as insulation, catalyst, etc. Mesoporous alumina substrate consists of uniformly distributed, unconnected cylindrical pores. Near-field radiative heat transfer cannot be ignored, when the diameters of the pores are less than the characteristic wavelength of thermal radiation. In this paper, near-field radiation across a cylindrical pore is simulated by employing the fluctuation dissipation theorem and Green function. Such factors as the diameter of the pore, and the temperature of the material are further analyzed. The research results show that the radiative heat transfer on a mesoscale is 2∼4 orders higher than on a macroscale. The heat flux and equivalent thermal conductivity of radiation across a cylindrical pore decrease exponentially with pore diameter increasing, while increase with temperature increasing. The calculated equivalent thermal conductivity of radiation is further developed to modify the thermal conductivity of the mesoporous alumina. The combined thermal conductivity of the mesoporous alumina is obtained by using porosity weighted dilute medium and compared with the measurement. The combined thermal conductivity of mesoporous silica decreases gradually with pore diameter increasing, while increases smoothly with temperature increasing, which is in good agreement with the experimental data. The larger the porosity, the more significant the near-field effect is, which cannot be ignored. (paper)

  3. Time step size selection for radiation diffusion calculations

    International Nuclear Information System (INIS)

    Rider, W.J.; Knoll, D.A.

    1999-01-01

    The purpose of this note is to describe a time step control technique as applied to radiation diffusion. Standard practice only provides a heuristic criteria related to the relative change in the dependent variables. The authors propose an alternative based on relatively simple physical principles. This time step control applies to methods of solution that are unconditionally stable and converges nonlinearities within a time step in the governing equations. Commonly, nonlinearities in the governing equations are evaluated using existing (old time) data. The authors refer to this as the semi-implicit (SI) method. When a method converges nonlinearities within a time step, the entire governing equation including all nonlinearities is self-consistently evaluated using advance time data (with appropriate time centering for accuracy)

  4. Radiation of Electron in the Field of Plane Light Wave

    International Nuclear Information System (INIS)

    Zelinsky, A.; Drebot, I.V.; Grigorev, Yu.N.; Zvonareva, O.D.; Tatchyn, R.

    2006-01-01

    Results of integration of a Lorentz equation for a relativistic electron moving in the field of running, plane, linear polarized electromagnetic wave are presented in the paper. It is shown that electron velocities in the field of the wave are almost periodic functions of time. For calculations of angular spectrum of electron radiation intensity expansion of the electromagnetic field in a wave zone into generalized Fourier series was used. Expressions for the radiation intensity spectrum are presented in the paper. Derived results are illustrated for electron and laser beam parameters of NSC KIPT X-ray generator NESTOR. It is shown that for low intensity of the interacting electromagnetic wave the results of energy and angular spectrum calculations in the frame of classical electrodynamics completely coincide with calculation results produced using quantum electrodynamics. Simultaneously, derived expressions give possibilities to investigate dependence of energy and angular Compton radiation spectrum on phase of interaction and the interacting wave intensity

  5. Strong field interaction of laser radiation

    International Nuclear Information System (INIS)

    Pukhov, Alexander

    2003-01-01

    The Review covers recent progress in laser-matter interaction at intensities above 10 18 W cm -2 . At these intensities electrons swing in the laser pulse with relativistic energies. The laser electric field is already much stronger than the atomic fields, and any material is instantaneously ionized, creating plasma. The physics of relativistic laser-plasma is highly non-linear and kinetic. The best numerical tools applicable here are particle-in-cell (PIC) codes, which provide the most fundamental plasma model as an ensemble of charged particles. The three-dimensional (3D) PIC code Virtual Laser-Plasma Laboratory runs on a massively parallel computer tracking trajectories of up to 10 9 particles simultaneously. This allows one to simulate real laser-plasma experiments for the first time. When the relativistically intense laser pulses propagate through plasma, a bunch of new physical effects appears. The laser pulses are subject to relativistic self-channelling and filamentation. The gigabar ponderomotive pressure of the laser pulse drives strong currents of plasma electrons in the laser propagation direction; these currents reach the Alfven limit and generate 100 MG quasistatic magnetic fields. These magnetic fields, in turn, lead to the mutual filament attraction and super-channel formation. The electrons in the channels are accelerated up to gigaelectronvolt energies and the ions gain multi-MeV energies. We discuss different mechanisms of particle acceleration and compare numerical simulations with experimental data. One of the very important applications of the relativistically strong laser beams is the fast ignition (FI) concept for the inertial fusion energy (IFE). Petawatt-class lasers may provide enough energy to isochorically ignite a pre-compressed target consisting of thermonuclear fuel. The FI approach would ease dramatically the constraints on the implosion symmetry and improve the energy gain. However, there is a set of problems to solve before the FI

  6. Topological magnetoelectric effects in microwave far-field radiation

    Energy Technology Data Exchange (ETDEWEB)

    Berezin, M.; Kamenetskii, E. O.; Shavit, R. [Microwave Magnetic Laboratory, Department of Electrical and Computer Engineering, Ben Gurion University of the Negev, Beer Sheva (Israel)

    2016-07-21

    Similar to electromagnetism, described by the Maxwell equations, the physics of magnetoelectric (ME) phenomena deals with the fundamental problem of the relationship between electric and magnetic fields. Despite a formal resemblance between the two notions, they concern effects of different natures. In general, ME-coupling effects manifest in numerous macroscopic phenomena in solids with space and time symmetry breakings. Recently, it was shown that the near fields in the proximity of a small ferrite particle with magnetic-dipolar-mode (MDM) oscillations have the space and time symmetry breakings and the topological properties of these fields are different from the topological properties of the free-space electromagnetic fields. Such MDM-originated fields—called magnetoelectric (ME) fields—carry both spin and orbital angular momenta. They are characterized by power-flow vortices and non-zero helicity. In this paper, we report on observation of the topological ME effects in far-field microwave radiation based on a small microwave antenna with a MDM ferrite resonator. We show that the microwave far-field radiation can be manifested with a torsion structure where an angle between the electric and magnetic field vectors varies. We discuss the question on observation of the regions of localized ME energy in far-field microwave radiation.

  7. Radiation reaction force and unification of electromagnetic and gravitational fields

    International Nuclear Information System (INIS)

    Lo, C.Y.; Goldstein, G.R.; Napier, A.

    1981-04-01

    A unified theory of electromagnetic and gravitational fields should modify classical electrodynamics such that the radiation reaction force is accounted for. The analysis leads to a five-dimensional unified theory of five variables. The theory is supported by showing that, for the case of a charged particle moving in a constant magnetic field, the radiation reaction force is indeed included. Moreover, this example shows explicitly that physical changes are associated with the fifth variable. Thus, the notion of a physical five-dimensional space should be seriously taken into consideration

  8. Radiation inactivation analysis of enzymes. Effect of free radical scavengers on apparent target sizes

    International Nuclear Information System (INIS)

    Eichler, D.C.; Solomonson, L.P.; Barber, M.J.; McCreery, M.J.; Ness, G.C.

    1987-01-01

    In most cases the apparent target size obtained by radiation inactivation analysis corresponds to the subunit size or to the size of a multimeric complex. In this report, we examined whether the larger than expected target sizes of some enzymes could be due to secondary effects of free radicals. To test this proposal we carried out radiation inactivation analysis on Escherichia coli DNA polymerase I, Torula yeast glucose-6-phosphate dehydrogenase, Chlorella vulgaris nitrate reductase, and chicken liver sulfite oxidase in the presence and absence of free radical scavengers (benzoic acid and mannitol). In the presence of free radical scavengers, inactivation curves are shifted toward higher radiation doses. Plots of scavenger concentration versus enzyme activity showed that the protective effect of benzoic acid reached a maximum at 25 mM then declined. Mannitol alone had little effect, but appeared to broaden the maximum protective range of benzoic acid relative to concentration. The apparent target size of the polymerase activity of DNA polymerase I in the presence of free radical scavengers was about 40% of that observed in the absence of these agents. This is considerably less than the minimum polypeptide size and may reflect the actual size of the polymerase functional domain. Similar effects, but of lesser magnitude, were observed for glucose-6-phosphate dehydrogenase, nitrate reductase, and sulfite oxidase. These results suggest that secondary damage due to free radicals generated in the local environment as a result of ionizing radiation can influence the apparent target size obtained by this method

  9. Characterization of beta radiation fields using radiochromic films

    International Nuclear Information System (INIS)

    Benavente, Jhonny A.; Silva, Teogenes A. da

    2011-01-01

    The objective of this work was to study the response of radiochromic films for beta radiation fields in terms of absorbed dose. The reliability of the EBT model Gafchromic radiochromic film was studied. A 9800 XL model Microtek, transmission scanner, a 369 model X-Rite optical densitometer and a Mini 1240 Shimadzu UV spectrophotometer were used for measurement comparisons. Calibration of the three systems was done with irradiated samples of radiochromic films with 0.1; 0.3; 0.5; 0.8; 1.0; 1.5; 2.0; 2.5; 3.0; 3.5; 4.5 e 5.0 Gy in beta radiation field from a Sr-90/Y-90 source. Calibration was performed by establishing a correlation between the absorbed dose values and the corresponding radiochromic responses. Results showed significant differences in the absorbed dose values obtained with the three methods. Absorbed dose values showed errors from 0.6 to 4.4%, 0.3 to 31.8% and 0.2 to 47.3% for the Microtek scanner, the X-Rite Densitometer and the Shimadzu spectrophotometer, respectively. Due to the easy acquisition and use for absorbed dose measurements, the densitometer and the spectrophotometer showed to be suitable techniques to evaluate radiation dose in relatively homogeneous fields. In the case of inhomogeneous fields or for a two dimension mapping of radiation fields to identify anisotropies, the scanner technique is the most recommended. (author)

  10. Radiation inactivation target size of rat adipocyte glucose transporters in the plasma membrane and intracellular pools

    International Nuclear Information System (INIS)

    Jacobs, D.B.; Berenski, C.J.; Spangler, R.A.; Jung, C.Y.

    1987-01-01

    The in situ assembly states of the glucose transport carrier protein in the plasma membrane and in the intracellular (microsomal) storage pool of rat adipocytes were assessed by studying radiation-induced inactivation of the D-glucose-sensitive cytochalasin B binding activities. High energy radiation inactivated the glucose-sensitive cytochalasin B binding of each of these membrane preparations by reducing the total number of the binding sites without affecting the dissociation constant. The reduction in total number of binding sites was analyzed as a function of radiation dose based on target theory, from which a radiation-sensitive mass (target size) was calculated. When the plasma membranes of insulin-treated adipocytes were used, a target size of approximately 58,000 daltons was obtained. For adipocyte microsomal membranes, we obtained target sizes of approximately 112,000 and 109,000 daltons prior to and after insulin treatment, respectively. In the case of microsomal membranes, however, inactivation data showed anomalously low radiation sensitivities at low radiation doses, which may be interpreted as indicating the presence of a radiation-sensitive inhibitor. These results suggest that the adipocyte glucose transporter occurs as a monomer in the plasma membrane while existing in the intracellular reserve pool either as a homodimer or as a stoichiometric complex with a protein of an approximately equal size

  11. Monte Carlo modelling of a-Si EPID response: The effect of spectral variations with field size and position

    International Nuclear Information System (INIS)

    Parent, Laure; Seco, Joao; Evans, Phil M.; Fielding, Andrew; Dance, David R.

    2006-01-01

    This study focused on predicting the electronic portal imaging device (EPID) image of intensity modulated radiation treatment (IMRT) fields in the absence of attenuation material in the beam with Monte Carlo methods. As IMRT treatments consist of a series of segments of various sizes that are not always delivered on the central axis, large spectral variations may be observed between the segments. The effect of these spectral variations on the EPID response was studied with fields of various sizes and off-axis positions. A detailed description of the EPID was implemented in a Monte Carlo model. The EPID model was validated by comparing the EPID output factors for field sizes between 1x1 and 26x26 cm 2 at the isocenter. The Monte Carlo simulations agreed with the measurements to within 1.5%. The Monte Carlo model succeeded in predicting the EPID response at the center of the fields of various sizes and offsets to within 1% of the measurements. Large variations (up to 29%) of the EPID response were observed between the various offsets. The EPID response increased with field size and with field offset for most cases. The Monte Carlo model was then used to predict the image of a simple test IMRT field delivered on the beam axis and with an offset. A variation of EPID response up to 28% was found between the on- and off-axis delivery. Finally, two clinical IMRT fields were simulated and compared to the measurements. For all IMRT fields, simulations and measurements agreed within 3%--0.2 cm for 98% of the pixels. The spectral variations were quantified by extracting from the spectra at the center of the fields the total photon yield (Y total ), the photon yield below 1 MeV (Y low ), and the percentage of photons below 1 MeV (P low ). For the studied cases, a correlation was shown between the EPID response variation and Y total , Y low , and P low

  12. Maximal near-field radiative heat transfer between two plates

    Science.gov (United States)

    Nefzaoui, Elyes; Ezzahri, Younès; Drévillon, Jérémie; Joulain, Karl

    2013-09-01

    Near-field radiative transfer is a promising way to significantly and simultaneously enhance both thermo-photovoltaic (TPV) devices power densities and efficiencies. A parametric study of Drude and Lorentz models performances in maximizing near-field radiative heat transfer between two semi-infinite planes separated by nanometric distances at room temperature is presented in this paper. Optimal parameters of these models that provide optical properties maximizing the radiative heat flux are reported and compared to real materials usually considered in similar studies, silicon carbide and heavily doped silicon in this case. Results are obtained by exact and approximate (in the extreme near-field regime and the electrostatic limit hypothesis) calculations. The two methods are compared in terms of accuracy and CPU resources consumption. Their differences are explained according to a mesoscopic description of nearfield radiative heat transfer. Finally, the frequently assumed hypothesis which states a maximal radiative heat transfer when the two semi-infinite planes are of identical materials is numerically confirmed. Its subsequent practical constraints are then discussed. Presented results enlighten relevant paths to follow in order to choose or design materials maximizing nano-TPV devices performances.

  13. Radiation field mapping in mammography units with TLDs

    Energy Technology Data Exchange (ETDEWEB)

    Castro, J.C.O.; Silva, J.O., E-mail: jonas.silva@ufg.br [Universidade Federal de Goiás (IFG), Goiânia (Brazil). Instituto de Física; Veneziani, G.R. [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo-SP (Brazil). Centro de Metrologia das Radiações

    2017-07-01

    Mammography is the most common imaging technique for breast cancer detection and its tracking. For dosimetry, is important to know the field intensity variation. In this work, TLD-100 were used to made a field mapping of a mammographic system from a hospital in Goiânia/GO. The maximum radiation intensity was 8 cm far from chest wall. The results obtained could be used in the optimization of the dosimetry in the equipment used in this work. (author)

  14. A study of build-up effects in high-energy radiation fields using a TEPC

    Energy Technology Data Exchange (ETDEWEB)

    Hoefert, M; Stevenson, G R [CERN, European Laboratory for Particle Physics, Geneva (Switzerland); Aroua, A [IAR, Institute for Applied Radiophysics, Lausanne (Switzerland); Sannikov, A V [IHEP, Institute for High-Energy Physics, Protvino (Russian Federation)

    1995-09-04

    A dose of 2 mSv close to the body surface of a pregnant woman is considered by ICRP to assure a dose limit of 1 mSv to the foetus. Such an assumption depends on the energy spectrum and composition of the external radiation field and it was tested in radiation fields containing high-energy particles similar to those found around high-energy particle accelerators and in air-craft. Measurements of dose and dose equivalent were performed as a function of wall thickness using a tissue-equivalent proportional counter (TEPC) in radiation fields at the CERN-EU Reference Radiation Facility. Results are presented both with respect to integral quantities and event size spectra. The decrease in dose and dose equivalent at a depth equivalent to that of the foetus was typically 10% in a high-energy stray radiation field and in the case of PuBe source neutrons amounted to only 30%. It is concluded that it would be prudent under such exposure conditions to limit the dose of a pregnant woman to 1 mSv in order to assure that the dose to the foetus remains below the same limit. (author)

  15. A study of build-up effects in high-energy radiation fields using a TEPC

    International Nuclear Information System (INIS)

    Hoefert, M.; Stevenson, G.R.; Aroua, A.; Sannikov, A.V.

    1995-01-01

    A dose of 2 mSv close to the body surface of a pregnant woman is considered by ICRP to assure a dose limit of 1 mSv to the foetus. Such an assumption depends on the energy spectrum and composition of the external radiation field and it was tested in radiation fields containing high-energy particles similar to those found around high-energy particle accelerators and in air-craft. Measurements of dose and dose equivalent were performed as a function of wall thickness using a tissue-equivalent proportional counter (TEPC) in radiation fields at the CERN-EU Reference Radiation Facility. Results are presented both with respect to integral quantities and event size spectra. The decrease in dose and dose equivalent at a depth equivalent to that of the foetus was typically 10% in a high-energy stray radiation field and in the case of PuBe source neutrons amounted to only 30%. It is concluded that it would be prudent under such exposure conditions to limit the dose of a pregnant woman to 1 mSv in order to assure that the dose to the foetus remains below the same limit. (author)

  16. Strain-induced modulation of near-field radiative transfer.

    Science.gov (United States)

    Ghanekar, Alok; Ricci, Matthew; Tian, Yanpei; Gregory, Otto; Zheng, Yi

    2018-06-11

    In this theoretical study, we present a near-field thermal modulator that exhibits change in radiative heat transfer when subjected to mechanical stress/strain. The device has two terminals at different temperatures separated by vacuum: one fixed and one stretchable. The stretchable side contains one-dimensional grating. When subjected to mechanical strain, the effective optical properties of the stretchable side are affected upon deformation of the grating. This results in modulation of surface waves across the interfaces influencing near-field radiative heat transfer. We show that for a separation of 100 nm, it is possible to achieve 25% change in radiative heat transfer for a strain of 10%.

  17. [Dynamics of biomacromolecules in coherent electromagnetic radiation field].

    Science.gov (United States)

    Leshcheniuk, N S; Apanasevich, E E; Tereshenkov, V I

    2014-01-01

    It is shown that induced oscillations and periodic displacements of the equilibrium positions occur in biomacromolecules in the absence of electromagnetic radiation absorption, due to modulation of interaction potential between atoms and groups of atoms forming the non-valence bonds in macromolecules by the external electromagnetic field. Such "hyperoscillation" state causes inevitably the changes in biochemical properties of macromolecules and conformational transformation times.

  18. Non-ionizing radiation exposure: electric field strength measurement ...

    African Journals Online (AJOL)

    In this research, the measured values are compared with the international standard recommended by ICNIRP then were also compared with previous study from several locations around Malaysia. The result shows an increase in the values of electromagnetic field radiation. The result of this study could be used for health ...

  19. Magnetic fields driven by tidal mixing in radiative stars

    Science.gov (United States)

    Vidal, Jérémie; Cébron, David; Schaeffer, Nathanaël; Hollerbach, Rainer

    2018-04-01

    Stellar magnetism plays an important role in stellar evolution theory. Approximatively 10 per cent of observed main sequence (MS) and pre-main-sequence (PMS) radiative stars exhibit surface magnetic fields above the detection limit, raising the question of their origin. These stars host outer radiative envelopes, which are stably stratified. Therefore, they are assumed to be motionless in standard models of stellar structure and evolution. We focus on rapidly rotating, radiative stars which may be prone to the tidal instability, due to an orbital companion. Using direct numerical simulations in a sphere, we study the interplay between a stable stratification and the tidal instability, and assess its dynamo capability. We show that the tidal instability is triggered regardless of the strength of the stratification (Brunt-Väisälä frequency). Furthermore, the tidal instability can lead to both mixing and self-induced magnetic fields in stably stratified layers (provided that the Brunt-Väisälä frequency does not exceed the stellar spin rate in the simulations too much). The application to stars suggests that the resulting magnetic fields could be observable at the stellar surfaces. Indeed, we expect magnetic field strengths up to several Gauss. Consequently, tidally driven dynamos should be considered as a (complementary) dynamo mechanism, possibly operating in radiative MS and PMS stars hosting orbital companions. In particular, tidally driven dynamos may explain the observed magnetism of tidally deformed and rapidly rotating Vega-like stars.

  20. Photovoltaic system sizing and performance by the comparison of demand and expected radiations

    Energy Technology Data Exchange (ETDEWEB)

    Lasnier, France; Sivoththaman, S [Asian Inst. of Tech., Bangkok (TH). Div. of Energy Technology

    1990-01-01

    Two models have been developed and proposed for the calculation of required radiation and for the prediction of available radiation (with a certain probability). These can be used for the sizing and performance prediction of stand-alone photovoltaic (PV) systems in a specified region. The first model computes the minimum daily average radiation required for the system to survive without failure, given the load and consecutive days-of-run. The component ratings of the system, PV panel size and battery size are observed to have great influence on the necessary radiation. The second model calculates the probable minimum radiation in the future, given the number of consecutive run-days and the percentage probability with which the values are to be minimized. The five-year radiation data for Bangkok (1983-1987) were statistically processed for use in the model as data. The output of the two models, when superimposed on each other, gives a clear idea about the system performance and about the optimum sizing. (author).

  1. Correlation between Auroral kilometric radiation and field-aligned currents

    International Nuclear Information System (INIS)

    Green, J.L.; Saflekos, N.A.; Gurnett, D.A.; Potemra, T.A.

    1982-01-01

    Simultaneous observations of field-aligned currents (FAC) and auroral kilometric radiation (AKR) are compared from the polar-orbiting satellites Triad and Hawkeye. The Triad observations were restricted to the evening-to-midnight local time sector (1900 to 0100 hours magnetic local time) in the northern hemisphere. This is the region in which the most intense storms of AKR are believed to originate. The Hawkeye observations were restricted to when the satellite was in the AKR emission cone in the northern hemisphere and at radial distances > or =7R/sub E/ (earth radii) to avoid local propagation cutoff effects. A(R/7R/sub E/) 2 normalization to the power flux measurements of the kilometric radiation from Hawkeye is used to take into account the radial dependence of this radiation and to scale all intensity measurements so that they are independent of Hawkeye's position in the emission cone. Integrated field-aligned current intensities from Triad are determined from the observed transverse magnetic field disturbances. There appears to be a weak correlation between AKR intensity and the integrated current sheet intensity of field-aligned currents. In general, as the intensity of auroral kilometric radiation increases so does the integrated auroral zone current sheet intensity increase. Statistically, the linear correlation coefficient between the log of the AKR power flux and the log of the current sheet intensity is 0.57. During weak AKR bursts ( - 18 W m - 2 Hz - 1 ), Triad always observed weak FAC'S ( - 1 ), and when Triad observed large FAC's (> or =0.6 A m - 1 ), the AKR intensity from Hawkeye was moderately intense (10 - 5 to 10 - 14 W m - 2 Hz - 1 ) to intense (>10 - 14 W m - 2 Hz - 1 ). It is not clear from these preliminary results what the exact role is that auroral zone field-aligned currents play in the generation or amplification of auroral kilometric radiation

  2. Analysis of radiation fields in tomography on diffusion gaseous sound

    International Nuclear Information System (INIS)

    Bekman, I.N.

    1999-01-01

    Perspectives of application of equilibrium and stationary variants of diffusion tomography with radioactive gaseous sounds for spatial reconstruction of heterogeneous media in materials technology were considered. The basic attention were allocated to creation of simple algorithms of detection of sound accumulation on the background of monotonically varying concentration field. Algorithms of transformation of two-dimensional radiation field in three-dimensional distribution of radiation sources were suggested. The methods of analytical elongation of concentration field permitting separation of regional anomalies on the background of local ones and vice verse were discussed. It was shown that both equilibrium and stationary variants of diffusion tomography detect the heterogeneity of testing material, provide reduction of spatial distribution of elements of its structure and give an estimation of relative degree of defectiveness

  3. Study of particle size distribution and formation mechanism of radioactive aerosols generated in high-energy neutron fields

    CERN Document Server

    Endo, A; Noguchi, H; Tanaka, S; Iida, T; Furuichi, S; Kanda, Y; Oki, Y

    2003-01-01

    The size distributions of sup 3 sup 8 Cl, sup 3 sup 9 Cl, sup 8 sup 2 Br and sup 8 sup 4 Br aerosols generated by irradiations of argon and krypton gases containing di-octyl phthalate (DOP) aerosols with 45 MeV and 65 MeV quasi-monoenergetic neutrons were measured in order to study the formation mechanism of radioactive particles in high energy radiation fields. The effects of the size distribution of the radioactive aerosols on the size of the added DOP aerosols, the energy of the neutrons and the kinds of nuclides were studied. The observed size distributions of the radioactive particles were explained by attachment of the radioactive atoms generated by the neutron-induced reactions to the DOP aerosols. (author)

  4. Wind field forecast for accidental release of radiative materials

    International Nuclear Information System (INIS)

    Kang Ling; Chen Jiayi; Cai Xuhui

    2003-01-01

    A meso-scale wind field forecast model was designed for emergency environmental assessment in case of accidental release of radiative materials from a nuclear power station. Actual practice of the model showed that it runs fast, has wind field prediction function, and the result given is accurate. With meteorological data collected from weather stations, and pre-treated by a wind field diagnostic model, the initial wind fields at different times were inputted as initial values and assimilation fields for the forecasting model. The model, in turn, worked out to forecast meso-scale wind field of 24 hours in a horizontal domain of 205 km x 205 km. And then, the diagnostic model was employed again with the forecasting data to obtain more detail information of disturbed wind field by local terrain in a smaller domain of 20.5 km x 20.5 km, of which the nuclear power station is at the center. Using observation data in January, April, July and October of 1996 over the area of Hangzhou Bay, wind fields in these 4 months were simulated by different assimilation time and number of the weather stations for a sensitive test. Results indicated that the method used here has increased accuracy of the forecasted wind fields. And incorporating diagnostic method with the wind field forecast model has greatly increased efficiency of the wind field forecast for the smaller domain. This model and scheme have been used in Environmental Consequence Assessment System of Nuclear Accident in Qinshan Area

  5. The optimum circular field size for dental radiography with intraoral films

    NARCIS (Netherlands)

    Straaten, F.J. van; Aken, J. van

    Intraoral radiographs are often made with circular fields to irradiate the film, and in many instances these fields are much larger than the film. The feasibility of reducing a circular radiation field without increasing the probability of excessive cone cutting was evaluated clinically, and an

  6. Robust size illusion produced by expanding and contracting flow fields.

    Science.gov (United States)

    Dong, Xue; Bai, Jianying; Bao, Min

    2017-04-01

    A new illusion is described. Randomly positioned dots moved radially within an imaginary annular window. The dots' motion periodically changed the direction, leading to an alternating percept of expanding and contracting motion. Strikingly, the apparent size of the enclosed circular region shrank during the dots' expanding phases and dilated during the contracting phases. We quantitatively measured the illusion, and found that the presence of energy at the local kinetic edge could not account for the illusion. Besides, we reproduced the illusion on a natural scene background seen from a first-person point of view that moved forward and backward periodically. Blurring the boundaries of motion areas could not reverse the illusion in all subjects. Taken together, our observed illusion is likely induced by optic flow processing with some components of motion contrast. Expanding or contracting dots may induce the self-motion perception of either approaching or leaving way from the circle. These will make the circle appear smaller or larger since its retinal size remains constant. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. New theory of radiative energy transfer in free electromagnetic fields

    International Nuclear Information System (INIS)

    Wolf, E.

    1976-01-01

    A new theory of radiative energy transfer in free, statistically stationary electromagnetic fields is presented. It provides a model for energy transport that is rigorous both within the framework of the stochastic theory of the classical field as well as within the framework of the theory of the quantized field. Unlike the usual phenomenological model of radiative energy transfer that centers around a single scalar quantity (the specific intensity of radiation), our theory brings into evidence the need for characterizing the energy transport by means of two (related) quantities: a scalar and a vector that may be identified, in a well-defined sense, with ''angular components'' of the average electromagnetic energy density and of the average Poynting vector, respectively. Both of them are defined in terms of invariants of certain new electromagnetic correlation tensors. In the special case when the field is statistically homogeneous, our model reduces to the usual one and our angular component of the average electromagnetic energy density, when multiplied by the vacuum speed of light, then acquires all the properties of the specific intensity of radiation. When the field is not statistically homogeneous our model approximates to the usual phenomenological one, provided that the angular correlations between plane wave modes of the field extend over a sufficiently small solid angle of directions about the direction of propagation of each mode. It is tentatively suggested that, when suitably normalized, our angular component of the average electromagnetic energy density may be interpreted as a quasi-probability (general quantum-mechancial phase-space distribution function, such as Wigner's) for the position and the momentum of a photon

  8. Ways of providing radiation resistance of magnetic field semiconductor sensors

    CERN Document Server

    Bolshakova, I A; Holyaka, R; Matkovskii, A; Moroz, A

    2001-01-01

    Hall magnetic field sensors resistant to hard ionizing irradiation are being developed for operation under the radiation conditions of space and in charged particle accelerators. Radiation resistance of the sensors is first determined by the properties of semiconductor materials of sensitive elements; we have used microcrystals and thin layers of III-V semiconductors. Applying complex doping by rare-earth elements and isovalent impurities in certain proportions, we have obtained magnetic field sensors resistant to irradiation by fast neutrons and gamma-quanta. Tests of their radiation resistance were carried out at IBR-2 at the Joint Institute for Nuclear Research (Dubna). When exposed to neutrons with E=0.1-13 MeV and intensity of 10 sup 1 sup 0 n cm sup - sup 2 s sup - sup 1 , the main parameter of the sensors - their sensitivity to magnetic fields - changes by no more than 0.1% up to fluences of 10 sup 1 sup 4 n cm sup - sup 2. Further improvement of radiation resistance of sensor materials is expected by ...

  9. Accreditation of laboratories in the field of radiation protection

    International Nuclear Information System (INIS)

    Galjanic, S.; Franic, Z.

    2005-01-01

    This paper gives a review of requirements and procedures for the accreditation of test and calibration laboratories in the field of radiation protection, paying particular attention to Croatia. General requirements to be met by a testing or calibration laboratory to be accredited are described in the standard HRN EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories. The quality of a radiation protection programme can only be as good as the quality of the measurements made to support it. Measurement quality can be assured by participation in measurement assurance programmes that evaluate the appropriateness of procedures, facilities, and equipment and include periodic checks to assure adequate performance. These also include internal consistency checks, proficiency tests, intercomparisons and site visits by technical experts to review operations. In Croatia, laboratories are yet to be accredited in the field of radiation protection. However, harmonisation of technical legislation with the EU legal system will require some changes in laws and regulations in the field of radiation protection, including the ones dealing with the notification of testing laboratories and connected procedures. Regarding the notification procedures for testing laboratories in Croatia, in the regulated area, the existing accreditation infrastructure, i.e. Croatian Accreditation Agency is ready for its implementation, as it has already established and further developed a consistent accreditation system, compatible with international requirements and procedures.(author)

  10. Estimate on the uncertainty of predicting radiated emission from near-field scan caused by insufficient or inaccurate near-field data

    DEFF Research Database (Denmark)

    Sørensen, Morten; Radchenko, Andriy; Kam, Keong

    2012-01-01

    Near-field scan on a Huygens’ box can be used in order to predict the maximal radiated emission from a Printed Circuit Board. The significance of step size and phase accuracy, and the importance of a full Huygens’ box are investigated by simulation of two different models with two different...... numerical methods. The prediction of maximal radiated emission is quite robust but the results also show that a full scan on all six surfaces is probably needed....

  11. A characteristic scale in radiation fields of fractal clouds

    Energy Technology Data Exchange (ETDEWEB)

    Wiscombe, W.; Cahalan, R.; Davis, A.; Marshak, A. [Goddard Space Flight Center, Greenbelt, MD (United States)

    1996-04-01

    The wavenumber spectrum of Landsat imagery for marine stratocumulus cloud shows a scale break when plotted on a double log plot. We offer an explanation of this scale break in terms of smoothing by horizontal radiative fluxes, which is parameterized and incorporated into an improved pixel approximation. We compute the radiation fields emerging from cloud models with horizontally variable optical depth fractal models. We use comparative spectral and multifractal analysis to qualify the validity of the independent pixel approximation at the largest scales and demonstrate it`s shortcomings on the smallest scales.

  12. Obligations and responsibilities in radiation protection in the medical field

    International Nuclear Information System (INIS)

    2011-01-01

    This document briefly presents the various obligations and responsibilities of the various actors involved in or concerned by radiation protection in the medical field: the hospital administration (with respect to workers and patients), the physician (authorization and declaration, justification, optimization), the medical electro-radiology operator, the person with expertise in medical radio-physics (PSRPM), the radio-pharmacist (he is required in nuclear medicine with internal use of pharmaceutical product), the personnel with expertise in radiation protection (PCR), and other health professionals

  13. A new non intercepting beam size diagnostics using diffraction radiation from a Slit

    International Nuclear Information System (INIS)

    Castellano, M.

    1996-09-01

    A new non interpreting beam size diagnostic for high charge electron beams is presented. This diagnostics is based on the analysis of the angular distribution of the 'diffracted' transition radiation emitted by the beam when crossing a slit cut in metallic foil. It allows a resolution better then the radiation transverse formation zone. Numerical results based on the parameters of the TTF FEL beam are given as example

  14. Electric field deformation in diamond sensors induced by radiation defects

    Energy Technology Data Exchange (ETDEWEB)

    Kassel, Florian; Boer, Wim de; Boegelspacher, Felix; Dierlamm, Alexander; Mueller, Thomas; Steck, Pia [Institut fuer Experimentelle Kernphysik (IEKP), Karlsruher Institut fuer Technologie (KIT) (Germany); Dabrowski, Anne; Guthoff, Moritz [CERN (Switzerland)

    2016-07-01

    The BCML system is a beam monitoring device in the CMS experiment at the LHC. As detectors 32 poly-crystalline CVD diamond sensors are positioned in a ring around the beam pipe at a distance of ±1.8 m and ±14.4 m from the interaction point. The radiation hardness of the diamond sensors in terms of measured signal during operation was significantly lower than expected from laboratory measurements. At high particle rates, such as those occurring during the operation of the LHC, a significant fraction of the defects act as traps for charge carriers. This space charge modifies the electrical field in the sensor bulk leading to a reduction of the charge collection efficiency (CCE). A diamond irradiation campaign was started to investigate the rate dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the Transient Current Technique, the CCE was measured. The experimental results were used to create an effective trap model that takes the radiation damage into account. Using this trap model the rate dependent electrical field deformation and the CCE were simulated with the software ''SILVACO TCAD''. This talk compares the experimental measurement results with the simulations.

  15. Influence of size effects on the radiation stability of nanocrystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimenko, N. N.; Smirnov, D. I., E-mail: rmta@miee.ru [National Research University of Electronic Technology “MIET” (Russian Federation); Medetov, N. A. [Kostanai Social and Technical University (Kazakhstan); Zaporozhan, O. A. [National Research University of Electronic Technology “MIET” (Russian Federation)

    2014-12-15

    The data reported in publications are analyzed, and on this basis, problems arising in studies of the radiation stability of nanostructures and nanomaterials are formulated. A phenomenological model of the radiation stability of such objects is considered. The model is based on the concept of the behavior of close Frenkel pairs. To test the model proposed in the study, the effect of the size factor on the degree of structural degradation in nanoporous silicon samples when irradiated with phosphorus ions is studied. The effect of elastic strains on the radiation stability of the structures is established.

  16. Breast Intensity-Modulated Radiation Therapy Reduces Time Spent With Acute Dermatitis for Women of All Breast Sizes During Radiation

    International Nuclear Information System (INIS)

    Freedman, Gary M.; Li Tianyu; Nicolaou, Nicos; Chen Yan; Ma, Charlie C.-M.; Anderson, Penny R.

    2009-01-01

    Purpose: To study the time spent with radiation-induced dermatitis during a course of radiation therapy for breast cancer in women treated with conventional or intensity-modulated radiation therapy (IMRT). Methods and Materials: The study population consisted of 804 consecutive women with early-stage breast cancer treated with breast-conserving surgery and radiation from 2001 to 2006. All patients were treated with whole-breast radiation followed by a boost to the tumor bed. Whole-breast radiation consisted of conventional wedged photon tangents (n = 405) earlier in the study period and mostly of photon IMRT (n = 399) in later years. All patients had acute dermatitis graded each week of treatment. Results: The breakdown of the cases of maximum acute dermatitis by grade was as follows: 3%, Grade 0; 34%, Grade 1; 61%, Grade 2; and 2%, Grade 3. The breakdown of cases of maximum toxicity by technique was as follows: 48%, Grade 0/1, and 52%, Grade 2/3, for IMRT; and 25%, Grade 0/1, and 75%, Grade 2/3, for conventional radiation therapy (p < 0.0001). The IMRT patients spent 82% of weeks during treatment with Grade 0/1 dermatitis and 18% with Grade 2/3 dermatitis, compared with 29% and 71% of patients, respectively, treated with conventional radiation (p < 0.0001). Furthermore, the time spent with Grade 2/3 toxicity was decreased in IMRT patients with small (p = 0.0015), medium (p < 0.0001), and large (p < 0.0001) breasts. Conclusions: Breast IMRT is associated with a significant decrease both in the time spent during treatment with Grade 2/3 dermatitis and in the maximum severity of dermatitis compared with that associated with conventional radiation, regardless of breast size.

  17. A Computational Model of Cellular Response to Modulated Radiation Fields

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, Stephen J., E-mail: stephen.mcmahon@qub.ac.uk [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Butterworth, Karl T. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); McGarry, Conor K. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Northern Ireland (United Kingdom); Trainor, Colman [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); O' Sullivan, Joe M. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Clinical Oncology, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, Northern Ireland (United Kingdom); Hounsell, Alan R. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Northern Ireland (United Kingdom); Prise, Kevin M. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom)

    2012-09-01

    Purpose: To develop a model to describe the response of cell populations to spatially modulated radiation exposures of relevance to advanced radiotherapies. Materials and Methods: A Monte Carlo model of cellular radiation response was developed. This model incorporated damage from both direct radiation and intercellular communication including bystander signaling. The predictions of this model were compared to previously measured survival curves for a normal human fibroblast line (AGO1522) and prostate tumor cells (DU145) exposed to spatially modulated fields. Results: The model was found to be able to accurately reproduce cell survival both in populations which were directly exposed to radiation and those which were outside the primary treatment field. The model predicts that the bystander effect makes a significant contribution to cell killing even in uniformly irradiated cells. The bystander effect contribution varies strongly with dose, falling from a high of 80% at low doses to 25% and 50% at 4 Gy for AGO1522 and DU145 cells, respectively. This was verified using the inducible nitric oxide synthase inhibitor aminoguanidine to inhibit the bystander effect in cells exposed to different doses, which showed significantly larger reductions in cell killing at lower doses. Conclusions: The model presented in this work accurately reproduces cell survival following modulated radiation exposures, both in and out of the primary treatment field, by incorporating a bystander component. In addition, the model suggests that the bystander effect is responsible for a significant portion of cell killing in uniformly irradiated cells, 50% and 70% at doses of 2 Gy in AGO1522 and DU145 cells, respectively. This description is a significant departure from accepted radiobiological models and may have a significant impact on optimization of treatment planning approaches if proven to be applicable in vivo.

  18. A Computational Model of Cellular Response to Modulated Radiation Fields

    International Nuclear Information System (INIS)

    McMahon, Stephen J.; Butterworth, Karl T.; McGarry, Conor K.; Trainor, Colman; O’Sullivan, Joe M.; Hounsell, Alan R.; Prise, Kevin M.

    2012-01-01

    Purpose: To develop a model to describe the response of cell populations to spatially modulated radiation exposures of relevance to advanced radiotherapies. Materials and Methods: A Monte Carlo model of cellular radiation response was developed. This model incorporated damage from both direct radiation and intercellular communication including bystander signaling. The predictions of this model were compared to previously measured survival curves for a normal human fibroblast line (AGO1522) and prostate tumor cells (DU145) exposed to spatially modulated fields. Results: The model was found to be able to accurately reproduce cell survival both in populations which were directly exposed to radiation and those which were outside the primary treatment field. The model predicts that the bystander effect makes a significant contribution to cell killing even in uniformly irradiated cells. The bystander effect contribution varies strongly with dose, falling from a high of 80% at low doses to 25% and 50% at 4 Gy for AGO1522 and DU145 cells, respectively. This was verified using the inducible nitric oxide synthase inhibitor aminoguanidine to inhibit the bystander effect in cells exposed to different doses, which showed significantly larger reductions in cell killing at lower doses. Conclusions: The model presented in this work accurately reproduces cell survival following modulated radiation exposures, both in and out of the primary treatment field, by incorporating a bystander component. In addition, the model suggests that the bystander effect is responsible for a significant portion of cell killing in uniformly irradiated cells, 50% and 70% at doses of 2 Gy in AGO1522 and DU145 cells, respectively. This description is a significant departure from accepted radiobiological models and may have a significant impact on optimization of treatment planning approaches if proven to be applicable in vivo.

  19. Computerized dosimetric system for studying radiation fields of afterloading apparatus

    International Nuclear Information System (INIS)

    Andryushin, O.S.; Gorshkov, M.I.

    1988-01-01

    Works on designing a computerized dosimetric scanner (CODOS) for studying radiation fields of remote therapeutic apparatus, providing dosimetric data input from semiconductor transducers and ionization chambers directly into the computer memory were carried out. The basic problems were to provide reproducibility and accuracy of the initial dosimetric data, formation of the data bank on LUEhV-15M1 accelerator bremsstrahlung and electron radiation fields. An extra problem was to provide isodose curves for manual scheduling of radiotherapy. The 15 VUMS-28-025 complex based on Elektronika-60 computer was chosen as a host computer, photodiodes were used as a semiconductor detector, the 70108 rod chamber and VA-J-18 dosemeters were used as an ionization chamber. The results of studies with the CODOS system have been shown that it meets the dosimetric requirements for therapeutic apparatus

  20. Neutron and photon spectrometry in mixed radiation fields

    International Nuclear Information System (INIS)

    Jancar, A.; Kopecky, Z.; Veskrna, M.

    2014-01-01

    Spectrometric measurements of the mixed fields of neutron and photon radiation in the workplaces with the L-R-0 research reactor located in the UJV Rez and with the Van de Graaff accelerator, located in the UTEF laboratories Prague, are presented in this paper. The experimental spectrometric measurements were performed using a newly developed digital measuring system, based on the technology of analog-digital converters with a very high sampling frequency (up to 2 GHz), in connection with organic scintillation detector, type BC-501A, and stilbene detector. The results of experimental measurements show high quality of spectrometry mixed fields of neutron and photon radiation across the wide dynamic range of measured energy. (authors)

  1. Fiber optic components compatibility with the PWR containment radiation field

    International Nuclear Information System (INIS)

    Breuze, G.; Serre, J.

    1990-01-01

    Present and future applications of fiber optics transmission in the nuclear industrial field are emphasized. Nuclear acceptance criteria for relevant electronic equipments in terms of radiation dose rate, integrated dose and required reliability are given. Ambient conditions of PWR containment are especially considered in the present paper. Experimental results of optical fibers and end-components exposed to 60 Co gamma rays are successively shown. Main radiation response characteristics up to 10 4 Gy (with dose rates of about 100 Gy.h -1 ) of both multimodal fiber families (step index and gradient index fibers) are compared. Predominant features of pure silica core fibers are: * an efficient photobleaching with near IR light from LED and LD commonly used in transmission data links, * a radiation hardening reducing induced losses down to 10 dB.km -1 in fine fibers up to date with latest developments. Dose rate effect on induced losses is also outlined for these fibers. Optoelectronic fiber-end components radiation response is good only for special LED (AsGa) and PD (Si). Radiation behavior of complex pigtailed LDM (laser diode + photodiode + Peltier element + thermistor) is not fully acceptable and technological improvements were made. Preliminary results are given. Two applications of fiber links transmitting data in a PWR containment and a hot cell are described. Hardening levels obtained and means required are given

  2. A study on size effect of carboxymethyl starch nanogel crosslinked by electron beam radiation

    International Nuclear Information System (INIS)

    Doan Binh; Pham Thi Thu Hong; Nguyen Ngoc Duy; Nguyen Thanh Duoc; Nguyen Nguyet Dieu

    2012-01-01

    The formation of carboxymethyl starch (CMS) nanogel with 50 nm less particle size was carried out through a radiation crosslinked process on the electron beam (EB) linear accelerator. Changes of intrinsic viscosities and weight averaged molecular weight in the CMS concentration, which ranged from 3 to 10 mg ml −1 in absorbed doses were investigated. There were some new peaks in the 1 H NMR spectra of CMS nanogel compared with those of CMS polymer. These results were anticipated that the predominant intramolecular crosslinking of dilute CMS aqueous solution occurred while being exposed to a short intense pulse of ionizing radiation. Hydrodynamic radius (often called particle size, R h ) and distribution of particle size were measured by a dynamic light scattering technique. The radiation yield of intermolecular crosslinking of CMS solution was calculated from the expression of G x (). The influence of the “size effect” was demonstrated by testing culture of Lactobacillus bacteria on MRS agar culture medium containing CMS nanogel and polymer. Results showed that the number of Lactobacillus bacteria growing on nanogel containing culture medium is about 170 cfu/ml and on polymer containing culture medium is only 6 cfu/ml. - Highlights: ► Carboxymethyl starch (CMS) nanogel consists of radiation intramolecular cross-linked polymeric particles, which are rather well dispersed and swollen in water. ► The nano-sized particles can be obtained from a high energy electron pulse triggered radiation process in a dilute CMS solution. ► Once Lactobacillus bacteria are cultured on a CMS nanogel containing medium, the “size effect” of the CMS nanogel will prove to be clearly superior to that of a CMS polymer.

  3. Field profile tailoring in a-Si:H radiation detectors

    International Nuclear Information System (INIS)

    Fujieda, I.; Cho, G.; Conti, M.; Drewery, J.; Kaplan, S.N.; Perez-Mendez, V.; Quershi, S.; Wildermuth, D.; Street, R.A.

    1990-03-01

    The capability of tailoring the field profile in reverse-biased a-Si:H diodes by doping and/or manipulating electrode shapes opens a way to many interesting device structures. Charge collection in a-Si:H radiation detectors is improved for high LET particle detection by inserting thin doped layers into the i-layer of the usual p-i-n diode. This buried p-i-n structure enables us to apply higher reverse-bias and the electric field is enhanced in the mid i-layer. Field profiles of the new structures are calculated and the improved charge collection process is discussed. Also discussed is the possibility of field profile tailoring by utilizing the fixed space charges in i-layers and/or manipulating electrode shapes of the reverse-biased p-i-n diodes. 10 refs., 7 figs

  4. Assessment of occupational exposure to radiofrequency fields and radiation

    International Nuclear Information System (INIS)

    Cooper, T. G.; Allen, S. G.; Blackwell, R. P.; Litchfield, I.; Mann, S. M.; Pope, J. M.; Van Tongeren, M. J. A.

    2004-01-01

    The use of personal monitors for the assessment of exposure to radiofrequency fields and radiation in potential future epidemiological studies of occupationally exposed populations has been investigated. Data loggers have been developed for use with a commercially available personal monitor and these allowed personal exposure records consisting of time-tagged measurements of electric and magnetic field strength to be accrued over extended periods of the working day. The instrumentation was worn by workers carrying out tasks representative of some of their typical daily activities at a variety of radio sites. The results indicated significant differences in the exposures of workers in various RF environments. A number of measures of exposure have been examined with a view to assessing possible exposure metrics for epidemiological studies. There was generally a good correlation between a given measure of electric field strength and the same measure of magnetic field strength. (authors)

  5. Laboratory Experiments on Rotation of Micron Size Cosmic Dust Grains with Radiation

    Science.gov (United States)

    Abbas, M. M.; Craven, P. D.; Spann, J. F.; Tankosic, D.; LeClair, A.; Gallagher, D. L.; West, E.; Weingartner, J.; Witherow, W. K.

    2004-01-01

    The processes and mechanisms involved in the rotation and alignment of interstellar dust grains have been of great interest in astrophysics ever since the surprising discovery of the polarization of starlight more than half a century ago. Numerous theories, detailed mathematical models and numerical studies of grain rotation and alignment along the Galactic magnetic field have been presented in the literature. In particular, the subject of grain rotation and alignment by radiative torques has been shown to be of particular interest in recent years. However, despite many investigations, a satisfactory theoretical understanding of the processes involved in grain rotation and alignment has not been achieved. As there appears to be no experimental data available on this subject, we have carried out some unique experiments to illuminate the processes involved in rotation of dust grains in the interstellar medium. In this paper we present the results of some preliminary laboratory experiments on the rotation of individual micron/submicron size nonspherical dust grains levitated in an electrodynamic balance evacuated to pressures of approx. 10(exp -3) to 10(exp -5) torr. The particles are illuminated by laser light at 5320 A, and the grain rotation rates are obtained by analyzing the low frequency (approx. 0-100 kHz) signal of the scattered light detected by a photodiode detector. The rotation rates are compared with simple theoretical models to retrieve some basic rotational parameters. The results are examined in the light of the current theories of alignment.

  6. Investigation of Radiation Fields at Aircraft Altitudes (invited paper)

    International Nuclear Information System (INIS)

    O'Sullivan, D.; Bartlett, D.; Grillmaier, R.; Heinrich, W.; Lindborg, L.; Schraube, H.; Silari, M.; Tommasino, L.; Zhou, D.

    2000-01-01

    Cosmic rays are believed to originate from several possible sources and recent research suggests that the bulk originate from the gas and dust of the interstellar medium and are accelerated by strong shock waves driven by supernova explosions. Cosmic ray particles are made up of γ98.5% hydrogen and helium and only 1.5% have charges greater than 2. Their average energy is about 1 GeV/nucleon and they lose energy through ionisation interactions and nuclear interactions with atoms of air as they penetrate deeply into the Earth's atmosphere. A very complicated radiation field develops as particles are generated by successive interaction of primary and secondary nuclei and a cascade of hadrons is produced in the atmosphere. The intensity of particles reaches a maximum at about 20 km above sea level (γ60 g.cm -2 ). The relative abundances of different particles change with depth within the atmosphere and mainly muons which are the decay products of charged mesons, reach sea level because of their weak interaction. The radiation field produced and consequently its effect on aircrew and frequent travellers is a matter of some concern. This paper outlines the results of investigations carried out to determine the characteristics of this radiation field and assess its impact on aircrew. (author)

  7. Radiation fields, dosimetry, biokinetics and biophysical models for cancer induction by ionising radiation 1996-1999. Executive summary

    International Nuclear Information System (INIS)

    Jacob, P.; Paretzke, H.G.; Roth, P.

    2000-01-01

    The Association Contract covers a range of research domains that are important to the Radiation Protection Research Action, especially in the areas 'Evaluation of Radiation Risks' and 'Understanding Radiation Mechanisms and Epidemiology'. Three research projects concentrate on radiation dosimetry research and two projects on the modelling of radiation carcinogenesis. The following list gives an overview on the topics and responsible scientific project leaders of the Association Contract: Study of radiation fields and dosimetry at aviation altitudes. Biokinetics and dosimetry of incorporated radionuclides. Dose reconstruction. Biophysical models for the induction of cancer by radiation. Experimental data for the induction of cancer by radiation of different qualities. (orig.)

  8. Extreme value paradigm for the effect of size of target volume on end results in radiation oncology

    International Nuclear Information System (INIS)

    Herbert, D.E.

    1983-01-01

    In clinical radiation oncology, it is commonly reported that complications of normal tissue occur more readily at larger field sizes for a given dose and recurrence of disease is observed more frequently from the larger tumors for a given dose. Cognate phenomena have long been observed in the study of the strength of materials. That is, the larger specimens will fracture under less applied stress, breakdown under less applied voltage, corrode in a shorter time, etc. The statistical theory of extreme values has provided both a rational explanation and a technique for exploitation of these ''size effects'' on the likelihood of specimen failure. This theory describes the relation which exists between the parameters (in particular, the location parameter) of the frequency distributions of the extreme values [smallest x(1) and largest x(n)] in a sample from a population of observations xi and the sample size n. It is shown in the present paper that the clinical failure phenomena are not inconsistent with the statistical theory of extreme values. The paper presents heuristic comparisons of the predictions of this theory with the received clinical observations of the effect of the size of the volume of irradiated tissues on the likelihood of occurrence of the misadventures of clinical radiation oncology: recurrence of disease and complication of normal tissue. The concordance of observations and predictions is acceptable. The quality and quantity of the currently available data have precluded the construction of any apodictic representations

  9. The right choice: extremity dosemeter for different radiation fields

    International Nuclear Information System (INIS)

    Brasik, N.; Stadtmann, H.; Kindl, P.

    2005-01-01

    Full text: Measurements of weakly penetrating radiation in personal dosimetry present problems in the design of suitable detectors and in the interpretation of their readings. For the measurement of the individual beta radiation dose, personal dosemeter for the fingers/tips are required. In general, the dosemeters currently used for personal monitoring of beta and low energy photon doses suffer from an energy threshold problem because the detector and/or the filter are too thick. TLDs of a standard thickness can seriously underestimate personal skin doses, especially in external fields of weakly penetrating radiation fields. LiF:Mg, Cu, P is a promising TL material which allows the production of thin detectors with sufficient sensitivity. Dosimetric properties of two different types of extremity dosemeters, designed to measure the personal dose equivalent Hp(0.07), have been compared: LiF:Mg, Ti (TLD100) and LiF:Mg, Cu, P (TLD700H). The first one consists of 100 mg.cm -2 LiF:Mg, Ti (TLD 100) chip and a 35mg. cm -2 cap, the other consists of a 7mg. cm -2 layer of LiF:Mg, Cu, P (TLD-700H) powder and a 5mg. cm -2 cap. The evaluation was done in two steps: performance tests (ISO-12794) and measurements in real workplaces. In the first step type test results for beta calibration were compared. In addition calibration for low energy photon radiation according to ISO 4037-3 was carried out. In the second step, simultaneous measurements with both types of dosemeters were performed at workplaces, where radiopharmaceuticals containing different radioisotopes are prepared and applied. Practices in these fields are characterized by handling of high activities at very small distances between source and skin. The results from the comparison of the two dosemeter types are presented and analyzed with respect to different radiation fields. Experiments showed a satisfactory sensitivity for the thinner dosemeter (TLD 700H) for detecting beta radiation at protection levels and a good

  10. 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).

  11. Twelve years of cooperation in the field of radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Grapengiesser, Sten; Bennerstedt, Torkel

    2005-06-01

    SSI has pursued an international cooperation program since 1992 within the field of radiation protection and emergency preparedness for radiation accidents with the three Baltic countries as main beneficiaries. As the Baltic countries are members of the EU since May 2004, this bilateral support will now be phased out and replaced with other forms of cooperation. During the years passed, a large number of activities have been launched with a total budget of some 14 million ECU. The Baltic radiation protection authorities have played a big role in the cooperation and Baltic ministries, universities, nuclear technology installations and other industries using radiation have also been engaged in the projects. SKI, SKB, Studsvik and the Swedish nuclear power plants should be mentioned as major cooperation partners on the Swedish side. During autumn 2004 when such a large coordinated work program was coming to an end, SSI decided to hold a seminar with the purpose to follow up experiences from the work and discuss coming forms of cooperation. The seminar took place on the 18 of November 2004 and gathered some 80 participants, 29 of which from the Baltic countries. It was opened by Lars-Erik Holm, the SSI Director General, and the three Baltic countries then presented their views and impressions from the passed years of cooperation. The seminar was concluded with a panel discussion on 'How to proceed from today's situation'. The result was that SSI invited to a new coordination meeting during autumn 2005 to follow up and discuss coordination of radiation protection around the Baltic Sea together with the other Nordic radiation protection authorities.

  12. Twelve years of cooperation in the field of radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Grapengiesser, Sten; Bennerstedt, Torkel

    2005-06-01

    SSI has pursued an international cooperation program since 1992 within the field of radiation protection and emergency preparedness for radiation accidents with the three Baltic countries as main beneficiaries. As the Baltic countries are members of the EU since May 2004, this bilateral support will now be phased out and replaced with other forms of cooperation. During the years passed, a large number of activities have been launched with a total budget of some 14 million ECU. The Baltic radiation protection authorities have played a big role in the cooperation and Baltic ministries, universities, nuclear technology installations and other industries using radiation have also been engaged in the projects. SKI, SKB, Studsvik and the Swedish nuclear power plants should be mentioned as major cooperation partners on the Swedish side. During autumn 2004 when such a large coordinated work program was coming to an end, SSI decided to hold a seminar with the purpose to follow up experiences from the work and discuss coming forms of cooperation. The seminar took place on the 18 of November 2004 and gathered some 80 participants, 29 of which from the Baltic countries. It was opened by Lars-Erik Holm, the SSI Director General, and the three Baltic countries then presented their views and impressions from the passed years of cooperation. The seminar was concluded with a panel discussion on 'How to proceed from today's situation'. The result was that SSI invited to a new coordination meeting during autumn 2005 to follow up and discuss coordination of radiation protection around the Baltic Sea together with the other Nordic radiation protection authorities.

  13. Twelve years of cooperation in the field of radiation protection

    International Nuclear Information System (INIS)

    Grapengiesser, Sten; Bennerstedt, Torkel

    2005-06-01

    SSI has pursued an international cooperation program since 1992 within the field of radiation protection and emergency preparedness for radiation accidents with the three Baltic countries as main beneficiaries. As the Baltic countries are members of the EU since May 2004, this bilateral support will now be phased out and replaced with other forms of cooperation. During the years passed, a large number of activities have been launched with a total budget of some 14 million ECU. The Baltic radiation protection authorities have played a big role in the cooperation and Baltic ministries, universities, nuclear technology installations and other industries using radiation have also been engaged in the projects. SKI, SKB, Studsvik and the Swedish nuclear power plants should be mentioned as major cooperation partners on the Swedish side. During autumn 2004 when such a large coordinated work program was coming to an end, SSI decided to hold a seminar with the purpose to follow up experiences from the work and discuss coming forms of cooperation. The seminar took place on the 18 of November 2004 and gathered some 80 participants, 29 of which from the Baltic countries. It was opened by Lars-Erik Holm, the SSI Director General, and the three Baltic countries then presented their views and impressions from the passed years of cooperation. The seminar was concluded with a panel discussion on 'How to proceed from today's situation'. The result was that SSI invited to a new coordination meeting during autumn 2005 to follow up and discuss coordination of radiation protection around the Baltic Sea together with the other Nordic radiation protection authorities

  14. Field oxide radiation damage measurements in silicon strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Laakso, M [Particle Detector Group, Fermilab, Batavia, IL (United States) Research Inst. for High Energy Physics (SEFT), Helsinki (Finland); Singh, P; Shepard, P F [Dept. of Physics and Astronomy, Univ. Pittsburgh, PA (United States)

    1993-04-01

    Surface radiation damage in planar processed silicon detectors is caused by radiation generated holes being trapped in the silicon dioxide layers on the detector wafer. We have studied charge trapping in thick (field) oxide layers on detector wafers by irradiating FOXFET biased strip detectors and MOS test capacitors. Special emphasis was put on studying how a negative bias voltage across the oxide during irradiation affects hole trapping. In addition to FOXFET biased detectors, negatively biased field oxide layers may exist on the n-side of double-sided strip detectors with field plate based n-strip separation. The results indicate that charge trapping occurred both close to the Si-SiO[sub 2] interface and in the bulk of the oxide. The charge trapped in the bulk was found to modify the electric field in the oxide in a way that leads to saturation in the amount of charge trapped in the bulk when the flatband/threshold voltage shift equals the voltage applied over the oxide during irradiation. After irradiation only charge trapped close to the interface is annealed by electrons tunneling to the oxide from the n-type bulk. (orig.).

  15. Effect of nano-oxide particle size on radiation resistance of iron–chromium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Weizong; Li, Lulu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Valdez, James A. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Saber, Mostafa [Department of Mechanical and Materials Engineering, Portland State University, Portland, OR 97201 (United States); Zhu, Yuntian, E-mail: ytzhu@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Koch, Carl C.; Scattergood, Ronald O. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States)

    2016-02-15

    Radiation resistance of Fe–14Cr alloys under 200 keV He irradiation at 500 °C was systematically investigated with varying sizes of nano oxide Zr, Hf and Cr particles. It is found that these nano oxide particles acted as effective sites for He bubble formation. By statistically analyzing 700–1500 He bubbles at the depth of about 150–700 nm from a series of HRTEM images for each sample, we established the variation of average He bubble size, He bubble density, and swelling percentage along the depth, and found them to be consistent with the He concentration profile calculated from the SIRM program. Oxide particles with sizes less than 3.5–4 nm are found most effective for enhancing radiation resistance in the studied alloy systems.

  16. Application of γ field theory based calculation method to the monitoring of mine nuclear radiation environment

    International Nuclear Information System (INIS)

    Du Yanjun; Liu Qingcheng; Liu Hongzhang; Qin Guoxiu

    2009-01-01

    In order to find the feasibility of calculating mine radiation dose based on γ field theory, this paper calculates the γ radiation dose of a mine by means of γ field theory based calculation method. The results show that the calculated radiation dose is of small error and can be used to monitor mine environment of nuclear radiation. (authors)

  17. Analysis of radiation pneumonitis outside the radiation field in breast conserving therapy for early breast cancer

    International Nuclear Information System (INIS)

    Ogo, Etsuyo; Fujimoto, Kiminori; Hayabuchi, Naofumi

    2002-01-01

    In a retrospective study of radiation-induced pulmonary changes for patients with breast conserving therapy for early breast cancer, we sent questionnaires to the main hospitals in Japan. In this study, we analyzed pulmonary changes after tangential whole-breast irradiation. The purpose of this study was to determine the incidence and risk factors for radiation pneumonitis outside the radiation field. The questionnaires included patients data, therapy data, and lung injury information between August 1999 and May 2000. On the first questionnaires, answer letters were received from 107 institutions out of 158 (67.7%). On the second questionnaires, response rate (hospitals which had radiation pneumonitis outside the radiation field) was 21.7% (23/106). We could find no risk factors of this type of pneumonitis. We suggested that lung irradiation might trigger this type of pneumonitis which is clinically similar to BOOP (bronchiolitis obliterans organizing pneumonia). It developed in 1.5-2.1% among the patients with breast conserving surgery and tangential whole-breast irradiation. And it is likely appeared within 6 months after radiotherapy. (author)

  18. Radiation corrections to quantum processes in an intense electromagnetic field

    International Nuclear Information System (INIS)

    Narozhny, N.B.

    1979-01-01

    A derivation of an asymptotic expression for the mass correction of order α to the electron propagator in an intense electromagnetic field is presented. It is used for the calculation of radiation corrections to the electron and photon elastic scattering amplitudes in the α 3 approximation. All proper diagrams contributing to the amplitudes and containing the above-mentioned correction to the propagator were considered, but not those which include vertex corrections. It is shown that the expansion parameter of the perturbation theory of quantum electrodynamics in intense fields grows not more slowly than αchi/sup 1/3/ at least for the electron amplitude, where chi = [(eF/sub μν/p/sub ν/) 2 ] 12 /m 3 , p is a momentum of the electron, and F is the electromagnetic field tensor

  19. Finite-element-analysis of fields radiated from ICRF antenna

    International Nuclear Information System (INIS)

    Yamanaka, Kaoru; Sugihara, Ryo.

    1984-04-01

    In several simple geometries, electromagnetic fields radiated from a loop antenna, on which a current oscillately flows across the static magnetic field B-vector 0 , are calculated by the finite element method (FEM) as well as by analytic methods in a cross section of a plasma cylinder. A finite wave number along B-vector 0 is assumed. Good agreement between FEM and the analytic solutions is obtained, which indicates the accuracy of FEM solutions. The method is applied to calculations of fields from a half-turn antenna and reasonable results are obtained. It is found that a straightforward application of FEM to problems in an anisotropic medium may bring about erroneous results and that an appropriate coordinate transformation is needed for FEM to become applicable. (author)

  20. Controlling radiation fields in siemans designed light water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Riess, R.; Marchl, T. [Siemens Power Generation Group, Erlangen (Germany)

    1995-03-01

    An essential item for the control of radiation fields is the minimization of the use of satellites in the reactor systems of Light Water Reactors (LWRs). A short description of the qualification of Co-replacement materials will be followed by an illustration of the locations where these materials were implemented in Siemens designed LWRs. Especially experiences in PWRs show the immense influence of reduction of cobalt sources on dose rate buildup. The corrosion and the fatique and wear behavior of the replacement materials has not created concern up to now. A second tool to keep occupational radiation doses at a low level in PWRs is the use of the modified B/Li-chemistry. This is practized in Siemens designed plants by keeping the Li level at a max. value of 2 ppm until it reaches a pH (at 300{degrees}C) of {approximately}7.4. This pH is kept constant until the end of the cycle. The substitution of cobalt base alloys and thus the removal of the Co-59 sources from the system had the largest impact on the radiation levels. Nonetheless, the effectiveness of the coolant chemistry should not be neglected either. Several years of successful operation of PWRs with the replacement materials resulted in an occupational radiation exposure which is below 0.5 man-Sievert/plant and year.

  1. EVIDOS: Individual dosimetry in mixed neutron and photon radiation fields

    International Nuclear Information System (INIS)

    Vanhavere, F.

    2006-01-01

    The EVIDOS project (partly funded by the European Commission RTD Programme: Nuclear Energy, Euratom Framework Programme V, 1998-2002, Contract No FIKR-CT-2001-00175) aimed at improving individual monitoring in mixed neutron-photon radiation fields by evaluating the performance of routine and novel personal dosimeters for mixed radiation, and by giving guidelines for deriving sufficiently accurate values of personal dose equivalent from the readings of area survey instruments and dosimeters. The main objective of EVIDOS was to evaluate different methods for individual dosimetry in mixed neutron-photon work-places in nuclear industry. This implied a determination of the capabilities and limitations of personal dosimeters and the establishment of methods to enable sufficiently accurate values of personal dose equivalent from spectrometers, area survey instruments and routine personal dosimeters. Also novel electronic personal dosimeters were investigated. To this end spectrometric and dosimetric investigations in selected representative workplaces in nuclear industry where workers can receive significant neutron doses were performed. As part of this project, a number of tasks were executed, in particular: (1) the determination of the energy and direction distribution of the neutron fluence; (2) the derivation of the (conventionally true) values of radiation protection quantities; (3) the determination of the readings of routine and innovative personal dosimeters and of area monitors; and (4) the comparison between dosimeter readings and values of the radiation protection quantities

  2. High ionization radiation field remote visualization device - shielding requirements

    International Nuclear Information System (INIS)

    Fernandez, Antonio P. Rodrigues; Omi, Nelson M.; Silveira, Carlos Gaia da; Calvo, Wilson A. Pajero

    2011-01-01

    The high activity sources manipulation hot-cells use special and very thick leaded glass windows. This window provides a single sight of what is being manipulated inside the hot-cell. The use of surveillance cameras would replace the leaded glass window, provide other sights and show more details of the manipulated pieces, using the zoom capacity. Online distant manipulation may be implemented, too. The limitation is their low ionizing radiation resistance. This low resistance also limited the useful time of robots made to explore or even fix problematic nuclear reactor core, industrial gamma irradiators and high radioactive leaks. This work is a part of the development of a high gamma field remote visualization device using commercial surveillance cameras. These cameras are cheap enough to be discarded after the use for some hours of use in an emergency application, some days or some months in routine applications. A radiation shield can be used but it cannot block the camera sight which is the shield weakness. Estimates of the camera and its electronics resistance may be made knowing each component behavior. This knowledge is also used to determine the optical sensor type and the lens material, too. A better approach will be obtained with the commercial cameras working inside a high gamma field, like the one inside of the IPEN Multipurpose Irradiator. The goal of this work is to establish the radiation shielding needed to extend the camera's useful time to hours, days or months, depending on the application needs. (author)

  3. Zinc injection helps reduce radiation field buildup in BWRs

    International Nuclear Information System (INIS)

    Wood, C.

    1991-01-01

    The injection of zinc into the reactor water of BWRs (Boiling Water Reactors) was a technique developed by General Electric (GE) and the Electric Power Research Institute (EPRI) to control the buildup of radiation fields from cobalt-60 on out-of-core piping. The presence of 5-10ppb zinc in the reactor water reduces the growth of oxide films on stainless steel surfaces, thereby reducing the number of sites available for the incorporation of cobalt; zinc also competes with cobalt for the sites. In September 1990, EPRI organized a workshop at the request of several US utilities to provide a forum to discuss experiences with zinc injection. The meeting focused on six main issues: the effect of zinc on radiation fields in normal water chemistry; the radiation buildup in hydrogen water chemistry, with and without zinc; the effects of zinc-65; the corrosion of fuel cladding and structural materials; the performance of zinc injection and monitoring equipment; and planning for zinc injection. (author)

  4. Study on quantities of radiation protection in medical X-rays radiation field with polyhedron phantom

    International Nuclear Information System (INIS)

    Yuan Shuyu; Dai Guangfu; Zhang Liangan

    1997-01-01

    The author have studied tissue-equivalent material with the elemental composition recommended by report No.44 of ICRU. Three different calibration phantoms in shape have been prepared with the tissue-equivalent material in order to study the influence of the angular dependence factor R(d,α) in the radiation field of X-rays on the calibration of individual dose equivalent Hp(d). The requirement of mono-genous radiation field to calibrate several dosimeters on one phantom at the same time can be met by application of dodecahedron phantom, which is difficult on ICRU sphere. Angular dependence factor R(d,α) of 0 degree∼90 degree and conversion coefficients between individual dose equivalent Hp(0.07, α) and the exposure of radiation of different energies and different angles have been established by taking advantage of the dodecahedron. Besides, the authors have studied the variation relation between the individual dose equivalent Hp (10,α) and Hp(0.07,α) in the medical X-rays radiation field

  5. Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field

    Science.gov (United States)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2016-01-01

    A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to -50 dB was

  6. A contemporary decennial global Landsat sample of changing agricultural field sizes

    Science.gov (United States)

    White, Emma; Roy, David

    2014-05-01

    Agriculture has caused significant human induced Land Cover Land Use (LCLU) change, with dramatic cropland expansion in the last century and significant increases in productivity over the past few decades. Satellite data have been used for agricultural applications including cropland distribution mapping, crop condition monitoring, crop production assessment and yield prediction. Satellite based agricultural applications are less reliable when the sensor spatial resolution is small relative to the field size. However, to date, studies of agricultural field size distributions and their change have been limited, even though this information is needed to inform the design of agricultural satellite monitoring systems. Moreover, the size of agricultural fields is a fundamental description of rural landscapes and provides an insight into the drivers of rural LCLU change. In many parts of the world field sizes may have increased. Increasing field sizes cause a subsequent decrease in the number of fields and therefore decreased landscape spatial complexity with impacts on biodiversity, habitat, soil erosion, plant-pollinator interactions, and impacts on the diffusion of herbicides, pesticides, disease pathogens, and pests. The Landsat series of satellites provide the longest record of global land observations, with 30m observations available since 1982. Landsat data are used to examine contemporary field size changes in a period (1980 to 2010) when significant global agricultural changes have occurred. A multi-scale sampling approach is used to locate global hotspots of field size change by examination of a recent global agricultural yield map and literature review. Nine hotspots are selected where significant field size change is apparent and where change has been driven by technological advancements (Argentina and U.S.), abrupt societal changes (Albania and Zimbabwe), government land use and agricultural policy changes (China, Malaysia, Brazil), and/or constrained by

  7. Target size analysis of bioactive substances by radiation inactivation. Comparison with electron beam and. gamma. -ray

    Energy Technology Data Exchange (ETDEWEB)

    Kume, Tamikazu; Watanabe, Yuhei; Ishigaki, Isao; Hirose, Shigehisa

    1988-11-01

    The molecular sizes of various bioactive substances can be measured by the radiation inactivation method. The high energy electron beam (10 MeV) and /sup 60/Co-..gamma.. ray are mainly used for radiation inactivation method. When the practical electron accelerator (/similar to/ 3 MeV) is used for the method, the problems such as penetration and increase of temperature will arise. In this paper the radiation inactivation using 3MeV electron beam is investigated by comparison with ..gamma..-ray. When the plate type glass ampules (glass thickness 1 +- 0.1 mm) were used as the irradiation vessels, relatively uniform dose distribution was obtained. The temperature increased only from 21 degC to 35 degC by irradiation (0.77 mA, 100 passes, 100 kGy). Under the irradiation condition mentioned above, the molecular size of three enzymes were calculated from D/sub 37/ doses. The molecular sizes obtained by electron beam and ..gamma..-ray were 14,000 and 17,000 respectively for lysozyme, 33,000 for pepsin, and 191,000 and 164,000 for yeast alcohol dehydrogenase. These values agreed closely with the reported molecular weight, suggesting that the 3 MeV electron beam can also be used for the radiation inactivation under limited conditions.

  8. Mixed field radiation modification of polyurethanes based on castor oil

    International Nuclear Information System (INIS)

    Mortley, A.; Bonin, H.W.; Bui, V.T.

    2006-01-01

    Polyurethane is among the polymers and polymer-based composite materials being investigated at the Royal Military College of Canada for the fabrication of leak-tight containers for the long-term disposal of radioactive waste. Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of doses (0.0 - 3.0 MGy) produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The tensile mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. Increases in mechanical strength due to radiation-induced crosslinking and limitations of thermal curing were confirmed by tensile tests and changing 13 C-NMR and FTIR spectra. (author)

  9. Mixed field radiation modification of polyurethanes based on castor oil

    Energy Technology Data Exchange (ETDEWEB)

    Mortley, A.; Bonin, H.W.; Bui, V.T. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada)]. E-mail: aba.mortley@rmc.ca

    2006-07-01

    Polyurethane is among the polymers and polymer-based composite materials being investigated at the Royal Military College of Canada for the fabrication of leak-tight containers for the long-term disposal of radioactive waste. Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of doses (0.0 - 3.0 MGy) produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The tensile mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. Increases in mechanical strength due to radiation-induced crosslinking and limitations of thermal curing were confirmed by tensile tests and changing {sup 13}C-NMR and FTIR spectra. (author)

  10. A radiophotoluminescent glass plate system for medium-sized field dosimetry

    International Nuclear Information System (INIS)

    Nakagawa, Keiichi; Koyanagi, Hiroki; Shiraki, Takashi; Saegusa, Shigeki; Sasaki, Katsutake; Oritate, Takashi; Mima, Kazuo; Miyazawa, Masanori; Ishidoya, Tatsuyo; Ohtomo, Kuni; Yoda, Kiyoshi

    2005-01-01

    A two-dimensional radiophotoluminescent system for medium-sized field dosimetry has been developed using a silver-activated phosphate glass plate with a dimension of 120 mmx120 mmx1 mm and a readout unit comprising a UV excitation lamp and a CCD imager. A dose ranging from 0 to 400 cGy, provided by a 6 MV x-ray beam, was delivered to the glass plate oriented perpendicularly to the beam and positioned in a water phantom at a depth of 10 cm, where the center of the glass plate coincided with the linac isocenter. After the dose delivery, the glass plate was placed in the readout system. The CCD output intensity increased linearly with the applied dose. The angular dependence of response on the direction of radiation incidence was measured by rotating the glass plate in the water phantom, indicating that the output remained constant up to 75 deg. from perpendicular incident direction, followed by a steep reduction down to 85% at an angle of 90 deg. A lateral dose distribution resulting from a 60 mmx60 mm irradiation was compared between the glass plate and an x-ray film having had the same exposure, showing that the glass plate and the x-ray film led to identical dose distributions. The dose reproducibility for a glass plate and the sensitivity variation among different glass plates were also evaluated

  11. The feasibility of near-field ODR beam-size monitoring at 23 GeV at FACET

    International Nuclear Information System (INIS)

    Lumpkin, A.H.; Yao, C.-Y.; Hogan, M.; Muggli, P.

    2011-01-01

    Extension of near-field optical diffraction radiation (ODR) imaging to the 23 GeV beams at the proposed FACET facility at SLAC has been evaluated. The beam-size sensitivity at the 10- to 20-(micro)m sigma level based on a simple model will be reported. Polarization effects are also seen to be important and will be discussed. The comparisons to previous experimental results and the modeling results indicate sufficient feasibility for planning of the experiments in the coming year.

  12. The Feasibility of Near-field ODR Beam-size Monitoring at 23 GeV at FACET

    International Nuclear Information System (INIS)

    Lumpkin, A.H.; Yao, C.-Y.; Hogan, M.; Muggli, P.

    2012-01-01

    Extension of near-field optical diffraction radiation (ODR) imaging to the 23 GeV beams at the proposed FACET facility at SLAC has been evaluated. The beam-size sensitivity at the 10- to 20-(micro)m sigma level based on a simple model will be reported. Polarization effects are also seen to be important and will be discussed. The comparisons to previous experimental results and the modeling results indicate sufficient feasibility for planning of the experiments in the coming year.

  13. Characteristics of radiation field in living environment, 2

    International Nuclear Information System (INIS)

    Nagaoka, Toshi; Sakamoto, Ryuichi; Tsutsumi, Masahiro; Saito, Kimiaki; Moriuchi, Shigeru

    1990-01-01

    A series of environmental radiation survey was carried out on train lines within Tokyo metropolitan area to clarify the characteristics of radiation field in living environment. Eleven JR, 18 private and 10 subway lines were surveyed, which cover 97% of whole train lines in Tokyo district in terms of annual number of passengers. The characteristics of environmental radiation field on train lines were discussed. The mean absorbed dose rate in air due to γ-rays on the subway lines was higher than those on the JR and private lines. It is due to the difference in the radioactivity concentration and the distribution of surrounding materials as the γ-ray sources. On the other hand, the mean dose rate due to cosmic-rays on the subway lines was lower than those on the JR and private lines. It is due to the shielding effect of the upper materials such as soil or building materials of tunnels. The mean dose rates for the JR, private and subway lines were calculated using these obtained data. Though the ratio of mean dose rate of γ-rays to that of cosmic-rays for the subway lines was different from those for the JR and private lines, the sum of γ- and cosmic-ray dose rates for the JR, private and subway lines were comparable, 40∼50 nGy/h for any of them. These data will be useful for a precise and realistic evaluation of collective dose, considering the life style of the public and the variation characteristics of environmental radiation. (author)

  14. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, M., E-mail: marco.caresana@polimi.it [Politecnico di Milano, CESNEF, Dipartimento di Energia, via Ponzio 34/3, 20133 Milano (Italy); Denker, A. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Esposito, A. [IFNF-LNF, FISMEL, via E. Fermi 40, 00044 Frascati (Italy); Ferrarini, M. [CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Golnik, N. [Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, Sw. A. Boboli 8, 02-525 Warsaw (Poland); Hohmann, E. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Leuschner, A. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Luszik-Bhadra, M. [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany); Manessi, G. [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Mayer, S. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Ott, K. [Helmholtz-Zentrum Berlin, BESSYII, Albert-Einstein-Str.15, 12489 Berlin (Germany); Röhrich, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Trompier, F. [Institute for Radiological Protection and Nuclear Safety, F-92262 Fontenay aux Roses (France); Volnhals, M.; Wielunski, M. [Helmholtz Zentrum München, Ingolstädter Landstr. 1, D-85764 Neuherberg (Germany)

    2014-02-11

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.

  15. Functional size of vacuolar H+ pumps: Estimates from radiation inactivation studies

    International Nuclear Information System (INIS)

    Sarafian, V.; Poole, R.J.

    1991-01-01

    The PPase and the ATPase from red beet (Beta vulgaris) vacuolar membranes were subjected to radiation inactivation by a 60 Co source in both the native tonoplast and detergent-solubilized states, in order to determine their target molecular sizes. Analysis of the residual phosphohydrolytic and proton transport activities, after exposure to varying doses of radiation, yielded exponential relationships between the activities and radiation doses. The deduced target molecular sizes for PPase activity in native and solubilized membranes were 125kD and 259kD respectively and 327kD for H + -transport. This suggests that the minimum number of subunits of 67kD for PPi hydrolysis is two in the native state and four after Triton X-100 solubilization. At least four subunits would be required for H + -translocation. Analysis of the ATPase inactivation patterns revealed target sizes of 384kD and 495kD for ATP hydrolysis in native and solubilized tonoplast respectively and 430kD for H + -transport. These results suggest that the minimum size for hydrolytic or transport functions is relatively constant for the ATPase

  16. Field Deployable Gamma Radiation Detectors for DHS Use

    Energy Technology Data Exchange (ETDEWEB)

    Sanjoy Mukhopadhyay

    2007-08-01

    Recently, the Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial off-the-shelf and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS requirements in terms of sensitivity, resolution, response time, and reach-back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron's identiFINDER{trademark}, which primarily uses sodium iodide crystals (3.18 x 2.54cm cylinders) as gamma detectors, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack{trademark} that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity, better resolution, and faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation, and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system automatically triggers the saving of relevant

  17. Field Deployable Gamma Radiation Detectors for DHS Use

    International Nuclear Information System (INIS)

    Sanjoy Mukhopadhyay

    2007-01-01

    Recently, the Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial off-the-shelf and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS requirements in terms of sensitivity, resolution, response time, and reach-back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron's identiFINDER(trademark), which primarily uses sodium iodide crystals (3.18 x 2.54cm cylinders) as gamma detectors, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack(trademark) that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity, better resolution, and faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation, and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system automatically triggers the saving of relevant

  18. OH megamasers: dense gas & the infrared radiation field

    Science.gov (United States)

    Huang, Yong; Zhang, JiangShui; Liu, Wei; Xu, Jie

    2018-06-01

    To investigate possible factors related to OH megamaser formation (OH MM, L_{H2O}>10L_{⊙}), we compiled a large HCN sample from all well-sampled HCN measurements so far in local galaxies and identified with the OH MM, OH kilomasers (L_{H2O}gas and the dense gas, respectively), we found that OH MM galaxies tend to have stronger HCN emission and no obvious difference on CO luminosity exists between OH MM and non-OH MM. This implies that OH MM formation should be related to the dense molecular gas, instead of the low-density molecular gas. It can be also supported by other facts: (1) OH MMs are confirmed to have higher mean molecular gas density and higher dense gas fraction (L_{HCN}/L_{CO}) than non-OH MMs. (2) After taking the distance effect into account, the apparent maser luminosity is still correlated with the HCN luminosity, while no significant correlation can be found at all between the maser luminosity and the CO luminosity. (3) The OH kMs tend to have lower values than those of OH MMs, including the dense gas luminosity and the dense gas fraction. (4) From analysis of known data of another dense gas tracer HCO^+, similar results can also be obtained. However, from our analysis, the infrared radiation field can not be ruled out for the OH MM trigger, which was proposed by previous works on one small sample (Darling in ApJ 669:L9, 2007). On the contrary, the infrared radiation field should play one more important role. The dense gas (good tracers of the star formation) and its surrounding dust are heated by the ultra-violet (UV) radiation generated by the star formation and the heating of the high-density gas raises the emission of the molecules. The infrared radiation field produced by the re-radiation of the heated dust in turn serves for the pumping of the OH MM.

  19. Characteristics of outage radiation fields around various reactor components

    International Nuclear Information System (INIS)

    Verzilov, Y.; Husain, A.; Corbin, G.

    2008-01-01

    Full text: Activity monitoring surveys, consisting of gamma spectroscopy and dose rate measurements, of various CANDU station components such as the reactor face, feeder cabinet, steam generators and moderator heat exchangers are often performed during shutdown in order to trend the transport of activity around the primary heat transport and moderator systems. Recently, the increased dose expenditure for work such as feeder inspection and replacement in the reactor vault has also spurred interest in improved characterization of the reactor face fields to facilitate better ALARA decision making and hence a reduction in future dose expenditures. At present, planning for reactor face work is hampered by insufficient understanding of the relative contribution of the various components to the overall dose. In addition to the increased dose expenditure for work at the reactor face, maintenance work associated with horizontal flux detectors and liquid injection systems has also resulted in elevated dose expenditures. For instance at Darlington, radiation fields in the vicinity of horizontal flux detectors (HFD) and Liquid Injection Shutdown System (LISS) nozzle bellows are trending upwards with present contact fields being in the range 16-70 rem/h and working distance fields being in the range 100-500 mrem/h. This paper presents findings based on work currently being funded by the CANDU Owners Group. Measurements were performed at Ontario Power Generation's Pickering and Darlington nuclear stations. Specifically, the following are addressed: Characteristics of Reactor Vault Fields; Characteristics of Steam Generator Fields; Characteristics of Moderator Heat Exchanger Fields. Measurements in the reactor vault were performed at the reactor face, along the length of end fittings, along the length of feeders, at the bleed condenser and at the HFD and LISS nozzle bellows. Steam generator fields were characterized at various elevations above the tube sheet, with and without the

  20. Reference radiation fields - Simulated workplace neutron fields - Part 2: Calibration fundamentals related to the basic quantities

    International Nuclear Information System (INIS)

    2008-01-01

    ISO 8529-1, ISO 8529-2 and ISO 8529-3, deal with the production, characterization and use of neutron fields for the calibration of personal dosimeters and area survey meters. These International Standards describe reference radiations with neutron energy spectra that are well defined and well suited for use in the calibration laboratory. However, the neutron spectra commonly encountered in routine radiation protection situations are, in many cases, quite different from those produced by the sources specified in the International Standards. Since personal neutron dosimeters, and to a lesser extent survey meters, are generally quite energy dependent in their dose equivalent response, it might not be possible to achieve an appropriate calibration for a device that is used in a workplace where the neutron energy spectrum and angular distribution differ significantly from those of the reference radiation used for calibration. ISO 8529-1 describes four radionuclide based neutron reference radiations in detail. This part of ISO 12789 includes the specification of neutron reference radiations that were developed to closely resemble radiation that is encountered in practice

  1. Inner-shell photoionization in weak and strong radiation fields

    International Nuclear Information System (INIS)

    Southworth, S.H.; Dunford, R.W.; Ederer, D.L.; Kanter, E.P.; Kraessig, B.; Young, L.

    2004-01-01

    The X-ray beams presently produced at synchrotron-radiation facilities interact weakly with matter, and the observation of double photoionization is due to electron-electron interactions. The intensities of future X-ray free-electron lasers are expected to produce double photoionization by absorption of two photons. The example of double K-shell photoionization of neon is discussed in the one- and two-photon cases. We also describe an experiment in which X rays photoionize the K shell of krypton in the presence of a strong AC field imposed by an optical laser

  2. Radiation protection in the field of environmental protection

    International Nuclear Information System (INIS)

    Zhao Yamin

    2003-01-01

    The relationship of radiation protection with environmental protection, the sources that may give rise to the environmental radiation contamination, and the system of radiation protection and the fundamental principles and requirements for radiation environmental management are introduced. Some special radiation protection problems faced with in the radiation environmental management are discussed. (author)

  3. Estimation by radiation inactivation of the size of functional units governing Sendai and influenza virus fusion

    International Nuclear Information System (INIS)

    Bundo-Morita, K.; Gibson, S.; Lenard, J.

    1987-01-01

    The target sizes associated with fusion and hemolysis carried out by Sendai virus envelope glycoproteins were determined by radiation inactivation analysis. The target size for influenza virus mediated fusion with erythrocyte ghosts at pH 5.0 was also determined for comparison. Sendai-mediated fusion with erythrocyte ghosts at pH 7.0 was likewise inactivated exponentially with increasing radiation dose, yielding a target size of 60 +/- 6 kDa, a value consistent with the molecular weight of a single F-protein molecule. The inactivation curve for Sendai-mediated fusion with cardiolipin liposomes at pH 7.0, however, was more complex. Assuming a multiple target-single hit model, the target consisted of 2-3 units of ca. 60 kDa each. A similar target was seen if the liposome contained 10% gangliosides or if the reaction was measured at pH 5.0, suggesting that fusion occurred by the same mechanism at high and low pH. A target size of 261 +/- 48 kDa was found for Sendai-induced hemolysis, in contrast with influenza, which had a more complex target size for this activity. Sendai virus fusion thus occurs by different mechanisms depending upon the nature of the target membrane, since it is mediated by different functional units. Hemolysis is mediated by a functional unit different from that associated with erythrocyte ghost fusion or with cardiolipin liposome fusion

  4. Field experience in use of radiation instruments in Cirus reactor

    International Nuclear Information System (INIS)

    Ramesh, N.; Sharma, R.C.; Agarwal, S.K.; Sawant, D.K.; Yadav, R.K.B.; Prasad, S.K.

    2005-01-01

    Cirus, located at Bhabha Atomic Research Centre, is a 40 MW (Th) research reactor fuelled by natural uranium, moderated by heavy water and cooled by de-mineralized light water. Graphite is used as reflector in this reactor. The reactor, commissioned in the year 1960, was in operation with availability factor of about 70% till early nineties. There after signs of ageing started surfacing up. After ageing studies, refurbishment plan was finalized and executed during the period from 1997-2002. after successful refurbishment, the reactor is in operation at full power. A wide range of radiation instruments have been used at Cirus for online monitoring of the radiological status of various process systems and environmental releases. Also, variety of survey meters, counting systems and monitors have been used by the health physics unit of the reactor for radiation hazard control. Many of these instruments, which were originally of Canadian design, have undergone changes due to obsolescence or as part of upgradation. This paper describes the experience with the radiation instruments of Cirus, bringing out their effectiveness in meeting the design intent, difficulties faced in their field use, and modifications carried out based on the performance feed back. Also, this paper highlights the areas where further efforts are needed to develop nuclear instrumentation to further strengthen monitoring and surveillance. (author)

  5. Romanian Radiation Protection Training Experience in Medical Field

    International Nuclear Information System (INIS)

    Steliana Popescu, F.; Milu, C.; Naghi, E.; Calugareanu, L.; Stroe, F. M.

    2003-01-01

    Studies conducted by the Institute of Public Health Bucharest during the last years emphasised the need of appropriate radioprotection training in the medical field. With the assistance of the International Atomic Energy Agency in Vienna, the Pilot Centre on Clinical Radio pathology in the Institute of Public Health-Bucharest, provided, from 2000 a 7 modular courses (40 hours each), covering the basic topics of ionizing radiation, biological and physical dosimetry, effects of exposure to ionising radiation, radioprotection concepts, planning and medical response in case of a nuclear accident or radiological emergency. The courses are opened for all health specialists, especially for occupational health physicians, focusing on health surveillance of radiation workers and medical management of overexposed workers. Each module is followed up by an examination and credits. The multidisciplinary team of instructors was trained within several train-the-trainers courses, organised by IAEA. The paper discusses the evaluation of these 3 years experience in training and its feedback impact, the aim of the program being to develop a knowledge in the spirit of the new patterns of radiological protection, both for safety and communication with the public. (Author)

  6. Functional size of photosynthetic electron transport chain determined by radiation inactivation

    International Nuclear Information System (INIS)

    Pan, R.S.; Chen, L.F.; Wang, M.Y.; Tsal, M.Y.; Pan, R.L.; Hsu, B.D.

    1987-01-01

    Radiation inactivation technique was employed to determine the functional size of photosynthetic electron transport chain of spinach chloroplasts. The functional size for photosystem I+II(H 2 O to methylviologen) was 623 +/- 37 kilodaltons; for photosystem II (H 2 O to dimethylquinone/ferricyanide), 174 +/- 11 kilodaltons; and for photosystem I (reduced diaminodurene to methylviologen), 190 +/- 11 kilodaltons. The difference between 364 +/- 22 (the sum of 174 +/- 11 and 190 +/- 11) kilodaltons and 623 +/- 37 kilodaltons is partially explained to be due to the presence of two molecules of cytochrome b 6 /f complex of 280 kilodaltons. The molecular mass for other partial reactions of photosynthetic electron flow, also measured by radiation inactivation, is reported. The molecular mass obtained by this technique is compared with that determined by other conventional biochemical methods. A working hypothesis for the composition, stoichiometry, and organization of polypeptides for photosynthetic electron transport chain is proposed

  7. When Theory Meets Data: Comparing Model Predictions Of Hillslope Sediment Size With Field Measurements.

    Science.gov (United States)

    Mahmoudi, M.; Sklar, L. S.; Leclere, S.; Davis, J. D.; Stine, A.

    2017-12-01

    The size distributions of sediment produced on hillslopes and supplied to river channels influence a wide range of fluvial processes, from bedrock river incision to the creation of aquatic habitats. However, the factors that control hillslope sediment size are poorly understood, limiting our ability to predict sediment size and model the evolution of sediment size distributions across landscapes. Recently separate field and theoretical investigations have begun to address this knowledge gap. Here we compare the predictions of several emerging modeling approaches to landscapes where high quality field data are available. Our goals are to explore the sensitivity and applicability of the theoretical models in each field context, and ultimately to provide a foundation for incorporating hillslope sediment size into models of landscape evolution. The field data include published measurements of hillslope sediment size from the Kohala peninsula on the island of Hawaii and tributaries to the Feather River in the northern Sierra Nevada mountains of California, and an unpublished data set from the Inyo Creek catchment of the southern Sierra Nevada. These data are compared to predictions adapted from recently published modeling approaches that include elements of topography, geology, structure, climate and erosion rate. Predictive models for each site are built in ArcGIS using field condition datasets: DEM topography (slope, aspect, curvature), bedrock geology (lithology, mineralogy), structure (fault location, fracture density), climate data (mean annual precipitation and temperature), and estimates of erosion rates. Preliminary analysis suggests that models may be finely tuned to the calibration sites, particularly when field conditions most closely satisfy model assumptions, leading to unrealistic predictions from extrapolation. We suggest a path forward for developing a computationally tractable method for incorporating spatial variation in production of hillslope

  8. Reproducibility of irregular radiation fields for malignant lymphoma

    International Nuclear Information System (INIS)

    Mock, U.; Dieckmann, K.; Poetter, R.; Molitor, A.M.; Haverkamp, U.

    1998-01-01

    Purpose: Radiation treatment for malignant lymphoma requires large field irradiation with irregular blocks according to the individual anatomy and tumor configuration. For determination of safety margins (PTV) we quantitatively analysed the accuracy of field and block placement with regard to different anatomical regions. Patients and Methods: Forty patients with malignant lymphoma were irradiated using the classical supra-/infradiaphragmatic field arrangements. Treatment was performed with 10-MeV photons and irregularly shaped, large opposing fields. We evaluated the accuracy of field and block placements during the treatment courses by comparing the regularly performed verification - with the simulation films. Deviations were determined with respect to the field edges and the central axis, along the x- and z-axis. Results: With regard to the field edges, mean deviations of 2.0 mm and 3.4 mm were found along the x- and z-axis. The corresponding standard deviations were 3.4 mm and 5.5 mm, respectively. With regard to the shielding blocks, mean displacement along the x- and z-axis was 2.2 mm and 3.8 mm. In addition, overall standard deviations of 5.7 mm (x-axis) and 7.1 mm (z-axis) were determined. During the course of time an improved accuracy of block placement was notable. Conclusion: Systematic analysis of port films gives information for a better defining safety margins in external radiotherapy. Evaluation of verification films on a regular basis improves set-up accuracy by reducing displacements. (orig.) [de

  9. The effect of the geometry on the fluorescence radiation field

    International Nuclear Information System (INIS)

    Teodori, F.; Fernandez, J.E.; Molinari, V.

    2000-01-01

    In x-ray fluorescence spectroscopy a narrow photon beam is focused on the surface of the sample to stimulate the production of characteristic radiation which gives useful information about the composition of the target. Even if the interpretation of the measurement is simple, the quantification of the total emitted intensity is not straightforward because the primary photons are produced in the depth of the sample and only a fraction can reach the surface without colliding again with matter. In this work we show that the geometry of the system plays an important role in determining the properties of the 3D radiation field. By using the integral Boltzmann equation, we show that there exist a link among the source distribution, the boundary conditions, the emission points, the observation angles and the properties of the field of emitted radiation. To illustrate the influence of the geometry, the energy distribution of a continuos emission spectrum like the Compton one has been calculated, firstly. It is shown that the energy distribution of the Compton primary photons (coming out from a slab irradiated with an internal monochromatic and isotropic point source) changes with the orientation of the observation direction. Another example involves a second order effect which depends on a double collision in the specimen. It has been shown that the characteristic emission due to the photoelectric effect is accompanied by a (P,C) continuous contribution which introduces an asymmetry in the shape of the line. Computations in a 3D radiation field have shown that such asymmetry is strongly dependent on the observation direction with respect to the primary volume where the photoelectric effect is produced. This means that detection through a narrow collimator whose axis (assumed here as the observation direction) deviates from the centre of symmetry of the primary volume, will produce differently shaped characteristic lines depending on the extent and placement of the

  10. Difference in Understanding of the Need for Using Radiation in Various Fields between Students Majoring in Radiation and Non-Radiation Related Studies

    Energy Technology Data Exchange (ETDEWEB)

    Han, Eun Ok [Dept. of Radiological Tecknology, Daegu Health College, Daegu (Korea, Republic of)

    2011-12-15

    As a way of improving social receptivity of using radiation, this study looked into the difference of understanding the need of using radiation in various fields between students majoring in radiation and non-radiation related studies, who will influence public opinion in the long term. This study also provides data needed for developing efficient strategies for projects promoting the public's awareness of using radiation. Of the students in the 79 schools sampled, 24%(177) were in 4 year colleges and 146 were junior colleges in educational statistics service (http://cesi.kedi.re.kr) In November 2010 1,945 students were selected as a sample, and they were given surveys on the need of using radiation in different fields. As a result, both between students majoring in radiation and non-radiation related studies showed a high level of understanding the need for radiation in the medical field and showed a low level of understanding of the need for radiation in the agricultural field. In all 6 fields of radiation use, students majoring in radiation related studies showed higher levels of understanding for the need to use radiation than students majoring in radiation and non-radiation related studies. In each field, male students and those who have experience medical radiation and relevant education had higher level of understanding. This shows we need to improve the understanding of the cases of female students and those who have not had experiences with medical radiation and to provide relevant education through various kinds of information. The characteristics of the groups that are shown in the results of this study are considered to be helpful for efficiently for project promoting the public's awareness of using radiation.

  11. Difference in Understanding of the Need for Using Radiation in Various Fields between Students Majoring in Radiation and Non-Radiation Related Studies

    International Nuclear Information System (INIS)

    Han, Eun Ok

    2011-01-01

    As a way of improving social receptivity of using radiation, this study looked into the difference of understanding the need of using radiation in various fields between students majoring in radiation and non-radiation related studies, who will influence public opinion in the long term. This study also provides data needed for developing efficient strategies for projects promoting the public's awareness of using radiation. Of the students in the 79 schools sampled, 24%(177) were in 4 year colleges and 146 were junior colleges in educational statistics service (http://cesi.kedi.re.kr) In November 2010 1,945 students were selected as a sample, and they were given surveys on the need of using radiation in different fields. As a result, both between students majoring in radiation and non-radiation related studies showed a high level of understanding the need for radiation in the medical field and showed a low level of understanding of the need for radiation in the agricultural field. In all 6 fields of radiation use, students majoring in radiation related studies showed higher levels of understanding for the need to use radiation than students majoring in radiation and non-radiation related studies. In each field, male students and those who have experience medical radiation and relevant education had higher level of understanding. This shows we need to improve the understanding of the cases of female students and those who have not had experiences with medical radiation and to provide relevant education through various kinds of information. The characteristics of the groups that are shown in the results of this study are considered to be helpful for efficiently for project promoting the public's awareness of using radiation.

  12. Stabilization of the extra dimension size in RS model by bulk Higgs field

    International Nuclear Information System (INIS)

    Egorov, V O; Volobuev, I P

    2017-01-01

    An extension of the Standard Model is considered, which is built on the basis of a stabilized Randall-Sundrum model with two branes. The stabilization of the extra dimension size is achieved with the help of a five-dimensional Higgs field, which plays the role of the Goldberger-Wise field. The stabilization makes the radion massive, and all the fermion fields, which are assumed to be localized on the TeV brane, get their masses due to the interaction with the boundary value of the Higgs field. The gauge invariance of the theory demands that the electroweak gauge fields also live in the bulk. The equations of motion for the background field configurations and for the field fluctuations against a background solution are obtained. The interaction of the bulk Higgs field with the multidimensional gauge field is studied and possible values of the model parameters are estimated. (paper)

  13. Reference neutron radiations. Part 2: Calibration fundamentals of radiation protection devices related to the basic quantities characterizing the radiation field

    International Nuclear Information System (INIS)

    2000-01-01

    ISO 8529 consists of the following parts, under the general title Reference neutron radiations: Part 1: Characteristics and methods of production; Part 2: Calibration fundamentals of radiation protection devices related to the basic quantities characterizing the radiation field; Part 3: Calibration of area and personal dosimeters and determination of response as a function of energy and angle of incidence. This Part 2. of ISO 8529 takes as its starting point the neutron sources described in ISO 8529-1. It specifies the procedures to be used for realizing the calibration conditions of radiation protection devices in neutron fields produced by these calibration sources, with particular emphasis on the corrections for extraneous effects (e.g., the neutrons scattered from the walls of the calibration room). In this part of ISO 8529, particular emphasis is placed on calibrations using radionuclide sources (clauses 4 to 6) due to their widespread application, with less details given on the use of accelerator and reactor sources (8.2 and 8.3). This part of ISO 8529 then leads to ISO 8529-3 which gives conversion coefficients and the general rules and procedures for calibration

  14. Reliability of different mark-recapture methods for population size estimation tested against reference population sizes constructed from field data.

    Directory of Open Access Journals (Sweden)

    Annegret Grimm

    evaluate the performance of mark-recapture population size estimators under field conditions, which is essential for selecting an appropriate method and obtaining reliable results in ecology and conservation biology, and thus for sound management.

  15. Spin-torque oscillation in large size nano-magnet with perpendicular magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Linqiang, E-mail: LL6UK@virginia.edu [Department of Physics, University of Virginia, Charlottesville, VA 22904 (United States); Kabir, Mehdi [Department of Electrical & Computer Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Dao, Nam; Kittiwatanakul, Salinporn [Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Cyberey, Michael [Department of Electrical Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Wolf, Stuart A. [Department of Physics, University of Virginia, Charlottesville, VA 22904 (United States); Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Institute of Defense Analyses, Alexandria, VA 22311 (United States); Stan, Mircea [Department of Electrical & Computer Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Lu, Jiwei [Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States)

    2017-06-15

    Highlights: • 500 nm size nano-pillar device was fabricated by photolithography techniques. • A magnetic hybrid structure was achieved with perpendicular magnetic fields. • Spin torque switching and oscillation was demonstrated in the large sized device. • Micromagnetic simulations accurately reproduced the experimental results. • Simulations demonstrated the synchronization of magnetic inhomogeneities. - Abstract: DC current induced magnetization reversal and magnetization oscillation was observed in 500 nm large size Co{sub 90}Fe{sub 10}/Cu/Ni{sub 80}Fe{sub 20} pillars. A perpendicular external field enhanced the coercive field separation between the reference layer (Co{sub 90}Fe{sub 10}) and free layer (Ni{sub 80}Fe{sub 20}) in the pseudo spin valve, allowing a large window of external magnetic field for exploring the free-layer reversal. A magnetic hybrid structure was achieved for the study of spin torque oscillation by applying a perpendicular field >3 kOe. The magnetization precession was manifested in terms of the multiple peaks on the differential resistance curves. Depending on the bias current and applied field, the regions of magnetic switching and magnetization precession on a dynamical stability diagram has been discussed in details. Micromagnetic simulations are shown to be in good agreement with experimental results and provide insight for synchronization of inhomogeneities in large sized device. The ability to manipulate spin-dynamics on large size devices could be proved useful for increasing the output power of the spin-transfer nano-oscillators (STNOs).

  16. Potential scattering in the presence of a static magnetic field and a radiation field of arbitrary polarization

    Science.gov (United States)

    Ferrante, G.; Zarcone, M.; Nuzzo, S.; McDowell, M. R. C.

    1982-05-01

    Expressions are obtained for the total cross sections for scattering of a charged particle by a potential in the presence of a static uniform magnetic field and a radiation field of arbitrary polarization. For a Coulomb field this is closely related to the time reverse of photoionization of a neutral atom in a magnetic field, including multiphoton effects off-resonance. The model is not applicable when the radiation energy approaches one of the quasi-Landau state separations. The effects of radiation field polarization are examined in detail.

  17. Formation of comets by radiation pressure in the outer protosun. III. Dependence on the anisotropy of the radiation field

    International Nuclear Information System (INIS)

    Hills, J.G.; Sandford, M.T. Jr.

    1983-01-01

    A two-dimensional, radiation-hydrodynamic code with dust was used to study the effect of an anisotropic radiation field on the formation of comets in the outer protosun by the radiation pressure from the Sun and surrounding protostars. If the radiation field is isotropic, the results are very similar to those found earlier by analytic models. When the dust cloud is flanked on two sides by luminous walls of equal strength but with no radiation entering the cloud from the azimuthal direction (a radiation vise), most of the dust eventually squeezes out the sides of the vise. The sides are open to outward streaming radiation which carries the dust with it. However, the entrance of even a small amount of radiation from the sides causes the dust to drift inward to form the comet. The work given in this paper indicates that a highly anisotropic radiation field is not likely to prevent the formation of a comet. It distorts the shape of the inward drifting dust cloud. Initially, faster inward drift occurs along radii having the strongest inward radiation flux. This in turn causes the optical depth to increase faster along the perpendicular radii where the radiation field is the weakest. The increase in the optical depth eventually compensates for the low radiation flux, so as the cloud shrinks the radiation pressure increases faster at the surface of the cloud along those radius vectors where the radiation flux has a minimum. Although the dust cloud in the anisotropic radiation field attains a very irregular shape, eventually all parts of the cloud contract in unison and arrive at the center of the cloud at about the same time

  18. Highly Localized Acoustic Streaming and Size-Selective Submicrometer Particle Concentration Using High Frequency Microscale Focused Acoustic Fields.

    Science.gov (United States)

    Collins, David J; Ma, Zhichao; Ai, Ye

    2016-05-17

    Concentration and separation of particles and biological specimens are fundamental functions of micro/nanofluidic systems. Acoustic streaming is an effective and biocompatible way to create rapid microscale fluid motion and induce particle capture, though the >100 MHz frequencies required to directly generate acoustic body forces on the microscale have traditionally been difficult to generate and localize in a way that is amenable to efficient generation of streaming. Moreover, acoustic, hydrodynamic, and electrical forces as typically applied have difficulty manipulating specimens in the submicrometer regime. In this work, we introduce highly focused traveling surface acoustic waves (SAW) at high frequencies between 193 and 636 MHz for efficient and highly localized production of acoustic streaming vortices on microfluidic length scales. Concentration occurs via a novel mechanism, whereby the combined acoustic radiation and streaming field results in size-selective aggregation in fluid streamlines in the vicinity of a high-amplitude acoustic beam, as opposed to previous acoustic radiation induced particle concentration where objects typically migrate toward minimum pressure locations. Though the acoustic streaming is induced by a traveling wave, we are able to manipulate particles an order of magnitude smaller than possible using the traveling wave force alone. We experimentally and theoretically examine the range of particle sizes that can be captured in fluid streamlines using this technique, with rapid particle concentration demonstrated down to 300 nm diameters. We also demonstrate that locations of trapping and concentration are size-dependent, which is attributed to the combined effects of the acoustic streaming and acoustic forces.

  19. Dynamics of Charged Particles and their Radiation Field

    International Nuclear Information System (INIS)

    Poisson, E

    2006-01-01

    The motion of a charged particle interacting with its own electromagnetic field is an area of research that has a long history. On the one hand the theory ought to be straightforward to formulate: one has Maxwell's equations that tell the field how to behave and one has the Lorentz-force law that tells the particle how to move (given the field). On the other hand the theory is fundamentally ambiguous because of the field singularities that necessarily come with a point particle. While each separate sub-problem can easily be solved, to couple the field to the particle in a self-consistent treatment turns out to be tricky. I believe it is this dilemma that has been the main source of the endless fascination. For them it is also rooted in the fact that the electromagnetic self-force problem is deeply analogous to the gravitational self-force problem, which is of direct relevance to future gravitational wave observations. The motion of point particles in curved spacetime has been the topic of a recent Topical Review, and it was the focus of a recent Special Issue. Exceptions are Rohrlich's excellent text, which makes a very useful introduction to radiation reaction, and the Landau and Lifshitz classic, which contains what is probably the most perfect summary of the foundational ideas. It is therefore with some trepidation that I received Herbert Spohn's book, which covers both the classical and quantum theories of a charged particle coupled to its own field (the presentation is limited to flat spacetime). Is this the text that graduate students and researchers should turn to in order to get a complete and accessible education in radiation reaction? My answer is that while the book does indeed contain a lot of useful material, it is not a very accessible source of information, and it is certainly not a student-friendly textbook. Instead, the book presents a technical account of the author's personal take on the theory, and represents a culminating summary of the author

  20. Very small beam-size measurement by a reflective synchrotron radiation interferometer

    Directory of Open Access Journals (Sweden)

    T. Naito

    2006-12-01

    Full Text Available A synchrotron radiation (SR interferometer with Herschelian reflective optics has been developed for the measurement of beams of several μm in size. In a conventional refractive SR interferometer, the dispersion effect of the objective lens limits the instrument to a smaller range of beam-size measurements. To avoid this problem, we designed a Herschelian arrangement of reflective optics for the interferometer. The effectiveness of the reflective SR interferometer was confirmed at the KEK Accelerator Test Facility (ATF damping ring. The measured vertical beam size obtained using the reflective SR interferometer was 4.7   μm and the estimated vertical emittance was 0.97×10^{-11}   m.

  1. Visible-light beam size monitors using synchrotron radiation at CESR

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.T., E-mail: sw565@cornell.edu [Cornell Laboratory for Accelerator-Based Science and Education, Cornell University, Ithaca, NY 14853 (United States); Rubin, D.L.; Conway, J.; Palmer, M.; Hartill, D. [Cornell Laboratory for Accelerator-Based Science and Education, Cornell University, Ithaca, NY 14853 (United States); Campbell, R.; Holtzapple, R. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States)

    2013-03-01

    A beam profile monitor utilizing visible synchrotron radiation (SR) from a bending magnet has been designed and installed in Cornell Electron-Positron Storage Ring (CESR). The monitor employs a double-slit interferometer to measure both the horizontal and vertical beam sizes over a wide range of beam currents. By varying the separation of the slits, beam sizes ranging from 50 to 500 μm can be measured with a resolution of approximately 5 μm. To measure larger beam size (>500 μm), direct imaging can be employed by rotating the double slits away from SR beam path. By imaging the π-polarized component of SR, a small vertical beam size (∼70 μm) was measured during an undulator test run in CESR, which was consistent with the interferometer measurement. To measure the bunch length, a beam splitter is inserted to direct a fraction of light into a streak camera setup. This beam size monitor measures the transverse and longitudinal beam sizes simultaneously, which is successfully used for intrabeam scattering studies. Detailed error analysis is discussed.

  2. Size-dependent reactivity of magnetite nanoparticles: a field-laboratory comparison

    Science.gov (United States)

    Swindle, Andrew L.; Elwood Madden, Andrew S.; Cozzarelli, Isabelle M.; Benamara, Mourad

    2014-01-01

    Logistic challenges make direct comparisons between laboratory- and field-based investigations into the size-dependent reactivity of nanomaterials difficult. This investigation sought to compare the size-dependent reactivity of nanoparticles in a field setting to a laboratory analog using the specific example of magnetite dissolution. Synthetic magnetite nanoparticles of three size intervals, ∼6 nm, ∼44 nm, and ∼90 nm were emplaced in the subsurface of the USGS research site at the Norman Landfill for up to 30 days using custom-made subsurface nanoparticle holders. Laboratory analog dissolution experiments were conducted using synthetic groundwater. Reaction products were analyzed via TEM and SEM and compared to initial particle characterizations. Field results indicated that an organic coating developed on the particle surfaces largely inhibiting reactivity. Limited dissolution occurred, with the amount of dissolution decreasing as particle size decreased. Conversely, the laboratory analogs without organics revealed greater dissolution of the smaller particles. These results showed that the presence of dissolved organics led to a nearly complete reversal in the size-dependent reactivity trends displayed between the field and laboratory experiments indicating that size-dependent trends observed in laboratory investigations may not be relevant in organic-rich natural systems.

  3. Out-of-Field Cell Survival Following Exposure to Intensity-Modulated Radiation Fields

    International Nuclear Information System (INIS)

    Butterworth, Karl T.; McGarry, Conor K.; Trainor, Colman; O'Sullivan, Joe M.; Hounsell, Alan R.; Prise, Kevin M.

    2011-01-01

    Purpose: To determine the in-field and out-of-field cell survival of cells irradiated with either primary field or scattered radiation in the presence and absence of intercellular communication. Methods and Materials: Cell survival was determined by clonogenic assay in human prostate cancer (DU145) and primary fibroblast (AGO1552) cells following exposure to different field configurations delivered using a 6-MV photon beam produced with a Varian linear accelerator. Results: Nonuniform dose distributions were delivered using a multileaf collimator (MLC) in which half of the cell population was shielded. Clonogenic survival in the shielded region was significantly lower than that predicted from the linear quadratic model. In both cell lines, the out-of-field responses appeared to saturate at 40%-50% survival at a scattered dose of 0.70 Gy in DU-145 cells and 0.24 Gy in AGO1522 cells. There was an approximately eightfold difference in the initial slopes of the out-of-field response compared with the α-component of the uniform field response. In contrast, cells in the exposed part of the field showed increased survival. These observations were abrogated by direct physical inhibition of cellular communication and by the addition of the inducible nitric oxide synthase inhibitor aminoguanidine known to inhibit intercellular bystander effects. Additional studies showed the proportion of cells irradiated and dose delivered to the shielded and exposed regions of the field to impact on response. Conclusions: These data demonstrate out-of-field effects as important determinants of cell survival following exposure to modulated irradiation fields with cellular communication between differentially irradiated cell populations playing an important role. Validation of these observations in additional cell models may facilitate the refinement of existing radiobiological models and the observations considered important determinants of cell survival.

  4. Is more profound knowledge in the field of radiation nece--ssary for doctors

    International Nuclear Information System (INIS)

    Klener, V.

    1981-01-01

    Reasons are listed why doctors should have more profound knowledge in the field of radiation. Despite imperceptibility by human senses of ionizing radiation, the parameters characterizing irradiation can accurately be measured. The units of the said parameters are listed and characterized and the relationships are explained of the radiation dose and non-stochastic and stochastic radiation effects. (Ha)

  5. Regulatory inspections in nuclear plants in the field of radiation protection

    International Nuclear Information System (INIS)

    Hort, M.; Fuchsova, D.

    2014-01-01

    State Office for Nuclear Safety executes state administration and performs inspections at peaceful use of nuclear energy and ionizing radiation in the field of radiation protection and nuclear safety. Inspections on radiation protection at nuclear power plants are secured by inspectors of the Department of Radiation Protection in Fuel Cycle, who work at the Regional centre Brno and Ceske Budejovice. (authors)

  6. Classical calculation of radiative lifetimes of atomic hydrogen in a homogeneous magnetic field

    International Nuclear Information System (INIS)

    Horbatsch, M.W.; Hessels, E.A.; Horbatsch, M.

    2005-01-01

    Radiative lifetimes of hydrogenic atoms in a homogeneous magnetic field of moderate strength are calculated on the basis of classical radiation. The modifications of the Keplerian orbits due to the magnetic field are incorporated by classical perturbation theory. The model is complemented by a classical radiative decay calculation using the radiated Larmor power. A recently derived highly accurate formula for the transition rate of a field-free hydrogenic state is averaged over the angular momentum oscillations caused by the magnetic field. The resulting radiative lifetimes for diamagnetic eigenstates classified by n,m and the diamagnetic energy shift C compare well with quantum results

  7. Determining the effect of grain size and maximum induction upon coercive field of electrical steels

    Science.gov (United States)

    Landgraf, Fernando José Gomes; da Silveira, João Ricardo Filipini; Rodrigues-Jr., Daniel

    2011-10-01

    Although theoretical models have already been proposed, experimental data is still lacking to quantify the influence of grain size upon coercivity of electrical steels. Some authors consider a linear inverse proportionality, while others suggest a square root inverse proportionality. Results also differ with regard to the slope of the reciprocal of grain size-coercive field relation for a given material. This paper discusses two aspects of the problem: the maximum induction used for determining coercive force and the possible effect of lurking variables such as the grain size distribution breadth and crystallographic texture. Electrical steel sheets containing 0.7% Si, 0.3% Al and 24 ppm C were cold-rolled and annealed in order to produce different grain sizes (ranging from 20 to 150 μm). Coercive field was measured along the rolling direction and found to depend linearly on reciprocal of grain size with a slope of approximately 0.9 (A/m)mm at 1.0 T induction. A general relation for coercive field as a function of grain size and maximum induction was established, yielding an average absolute error below 4%. Through measurement of B50 and image analysis of micrographs, the effects of crystallographic texture and grain size distribution breadth were qualitatively discussed.

  8. The error analysis of field size variation in pelvis region by using immobilization device

    International Nuclear Information System (INIS)

    Kim, Ki Hwan; Kang, No Hyun; Kim, Dong Wuk; Kim, Jun Sang; Jang, Ji Young; Kim, Jae Sung; Kim, Yong Eun; Cho, Moon June

    2000-01-01

    In radiotherapy, it may happen to radiate surrounding normal tissue because of inconsistent field size by changing patient position during treatment. We are going to analyze errors reduced by using immobilization device with Electronic Portal Imaging Device(EPID) in this study. We had treated the twenty-one patients in pelvic region with 10 MV X-ray from Aug. 1998 to Aug. 1999 at chungnam National University Hospital. All patients were treated at supine position during treatment. They were separated to two groups, 11 patients without device and 10 patients with immobilization device. We used styrofoam for immobilization device and measured the error of anterior direction for x, y axis and lateral direction for z, y axis from simulation film to EPID image using matching technique. For no immobilization device group, the mean deviation values of x axis and y axis are 0.19 mm. 0.48 mm, respectively and the standard deviations of systematic deviation are 2.38 mm, 2.19 mm, respectively and of random deviation for x axis and y axis are 1.92 mm. 1.29 mm, respectively. The mean deviation values of z axis and y axis are -3.61 mm. 2.07 mm, respectively and the standard deviations of systematic deviation are 3.20 mm, 2.29 mm, respectively and of random deviation for z axis and y axis are 2.73 mm. 1.62 mm, respectively. For immobilization device group, the mean deviation values of x axis and y axis are 0.71 mm. -1.07 mm, respectively and the standard deviations of systematic deviation are 1.80 mm, 2.26 mm, respectively and the standard deviations of systematic deviation are 1.80 mm, 2.26 mm, respectively of random deviation for x axis and y axis are 1.56 mm. 1.27 mm, respectively. The mean deviation values of z axis and y axis are -1.76 mm. 1.08 mm, respectively and the standard deviations of systematic deviation are 1.87 mm, 2.83 mm, respectively and of random deviation for x axis and y axis are 1.68 mm, 1.65 mm, respectively. Because of reducing random and systematic error

  9. Scattering in an intense radiation field: Time-independent methods

    International Nuclear Information System (INIS)

    Rosenberg, L.

    1977-01-01

    The standard time-independent formulation of nonrelativistic scattering theory is here extended to take into account the presence of an intense external radiation field. In the case of scattering by a static potential the extension is accomplished by the introduction of asymptotic states and intermediate-state propagators which account for the absorption and induced emission of photons by the projectile as it propagates through the field. Self-energy contributions to the propagator are included by a systematic summation of forward-scattering terms. The self-energy analysis is summarized in the form of a modified perturbation expansion of the type introduced by Watson some time ago in the context of nuclear-scattering theory. This expansion, which has a simple continued-fraction structure in the case of a single-mode field, provides a generally applicable successive approximation procedure for the propagator and the asymptotic states. The problem of scattering by a composite target is formulated using the effective-potential method. The modified perturbation expansion which accounts for self-energy effects is applicable here as well. A discussion of a coupled two-state model is included to summarize and clarify the calculational procedures

  10. Particle size, magnetic field, and blood velocity effects on particle retention in magnetic drug targeting.

    Science.gov (United States)

    Cherry, Erica M; Maxim, Peter G; Eaton, John K

    2010-01-01

    A physics-based model of a general magnetic drug targeting (MDT) system was developed with the goal of realizing the practical limitations of MDT when electromagnets are the source of the magnetic field. The simulation tracks magnetic particles subject to gravity, drag force, magnetic force, and hydrodynamic lift in specified flow fields and external magnetic field distributions. A model problem was analyzed to determine the effect of drug particle size, blood flow velocity, and magnetic field gradient strength on efficiency in holding particles stationary in a laminar Poiseuille flow modeling blood flow in a medium-sized artery. It was found that particle retention rate increased with increasing particle diameter and magnetic field gradient strength and decreased with increasing bulk flow velocity. The results suggest that MDT systems with electromagnets are unsuitable for use in small arteries because it is difficult to control particles smaller than about 20 microm in diameter.

  11. Guided wave radiation in a finite-sized metallic or composite plate-like structure for its nondestructive testing

    International Nuclear Information System (INIS)

    Stevenin, Mathilde

    2016-01-01

    Different models are developed to provide generic tools for simulating nondestructive methods relying on elastic guided waves applied to metallic or composite plates. Various inspection methods of these structures exist or are under study. Most of them make use of ultrasonic sources of finite size; all are sensitive to reflection phenomena resulting from the finite size of the monitored objects. The developed models deal with transducer diffraction effects and edge reflection. As the interpretation of signals measured in guided wave inspection often uses the concept of modes, the models themselves are explicitly modal. The case of isotropic plates (metal) and anisotropic (multilayer composites) are considered; a general approach under the stationary phase approximation allows us to consider all the cases of interest. For the first, the validity of a Fraunhofer-like approximation leads to a very efficient computation of the direct and reflected fields radiated by a source. For the second, special attention is paid to the treatment of caustics. The stationary phase approximation being difficult to generalize, a model (so-called 'pencil model') of more geometrical nature is proposed with a high degree of genericity. It chains terms of isotropic or anisotropic propagation and terms of interaction with a boundary. The equivalence of the stationary phase approximation and the pencil model is demonstrated in the case of the radiation and reflection in an isotropic plate, for which an experimental validation is proceeded. (author) [fr

  12. Measuring the wobble of radiation field centers during gantry rotation and collimator movement on a linear accelerator

    International Nuclear Information System (INIS)

    Du, Weiliang; Gao, Song

    2011-01-01

    Purpose: The isocenter accuracy of a linear accelerator is often assessed with star-shot films. This approach is limited in its ability to quantify three dimensional wobble of radiation field centers (RFCs). The authors report a Winston-Lutz based method to measure the 3D wobble of RFCs during gantry rotation, collimator rotation, and collimator field size change. Methods: A stationary ball-bearing phantom was imaged using multileaf collimator-shaped radiation fields at various gantry angles, collimator angles, and field sizes. The center of the ball-bearing served as a reference point, to which all RFCs were localized using a computer algorithm with subpixel accuracy. Then, the gantry rotation isocenter and the collimator rotation axis were derived from the coordinates of these RFCs. Finally, the deviation or wobble of the individual RFC from the derived isocenter or rotation axis was quantified. Results: The results showed that the RFCs were stable as the field size of the multileaf collimator was varied. The wobble of RFCs depended on the gantry angle and the collimator angle and was reproducible, indicating that the mechanical imperfections of the linac were mostly systematic and quantifiable. It was found that the 3D wobble of RFCs during gantry rotation was reduced after compensating for a constant misalignment of the multileaf collimator. Conclusions: The 3D wobble of RFCs can be measured with submillimeter precision using the proposed method. This method provides a useful tool for checking and adjusting the radiation isocenter tightness of a linac.

  13. Measuring the wobble of radiation field centers during gantry rotation and collimator movement on a linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Du, Weiliang; Gao, Song [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas, 77030 (United States)

    2011-08-15

    Purpose: The isocenter accuracy of a linear accelerator is often assessed with star-shot films. This approach is limited in its ability to quantify three dimensional wobble of radiation field centers (RFCs). The authors report a Winston-Lutz based method to measure the 3D wobble of RFCs during gantry rotation, collimator rotation, and collimator field size change. Methods: A stationary ball-bearing phantom was imaged using multileaf collimator-shaped radiation fields at various gantry angles, collimator angles, and field sizes. The center of the ball-bearing served as a reference point, to which all RFCs were localized using a computer algorithm with subpixel accuracy. Then, the gantry rotation isocenter and the collimator rotation axis were derived from the coordinates of these RFCs. Finally, the deviation or wobble of the individual RFC from the derived isocenter or rotation axis was quantified. Results: The results showed that the RFCs were stable as the field size of the multileaf collimator was varied. The wobble of RFCs depended on the gantry angle and the collimator angle and was reproducible, indicating that the mechanical imperfections of the linac were mostly systematic and quantifiable. It was found that the 3D wobble of RFCs during gantry rotation was reduced after compensating for a constant misalignment of the multileaf collimator. Conclusions: The 3D wobble of RFCs can be measured with submillimeter precision using the proposed method. This method provides a useful tool for checking and adjusting the radiation isocenter tightness of a linac.

  14. SU-E-T-432: Field Size Influence On the Electron and Photon Spectra Within Small MV Field Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Benmakhlouf, H; Andreo, P [Department of Medical Physics, Karolinska University Hospital, Stockholm and Department of Physics, Medical Radiation Physics, Stockholm University (Sweden)

    2015-06-15

    Purpose: To investigate the influence of photon field size on the electron and photon fluence spectra in the active volume of small field detectors. Methods: The PENELOPE MC system based usercode PenEasy was used to calculate the material influence on the spectra by scoring the differential fluence in inserts of silicon, carbon, phosphorus and aluminium having 3 mm diameter and height. The spectra were then calculated inside the active volume of eleven detectors (ion chambers and solid-state detectors) whose geometry was simulated with great detail. The inserts/detectors were placed at 10 cm depth in a 30 cm x 30 cm x 30 cm water phantom and irradiated with 2.5 MeV photons and Varian Clinac 6 MV beams of small, medium and large size. Results: For all configurations, photon spectra in the scoring volume were similar to that in a small water volume except for additional characteristic x-ray peaks resulting from the material itself and from the materials surrounding the detectors (i.e. high-Z shielding the silicon). Electron fluence calculated in the inserts were up to 60% larger than in water; the difference increased with material density and decreasing field size. MC-calculated doses were compared to analytically determined collision kerma and restricted cema (cut-off=15keV). For the inserts, with large and medium fields K-col agreed with MC-dose, but K-col overestimated the dose for small fields due to lack of lateral CPE. For the detectors, up to 15% differences between K-col and the MC-dose were found. For all configurations the C-delta and MC-dose agreed within ±2%. Conclusion: The most relevant findings were that shielding affects substantially the photon spectra and material conditions the electron spectra, their field size dependence varying with the geometry configuration. These affect the values of factors entering into relative dosimetry.

  15. Determination of the quality index (Q) for photon beams at arbitrary field sizes.

    Science.gov (United States)

    Sauer, Otto A

    2009-09-01

    A commonly used beam quality index (Q) for high-energy photon beams is the tissue phantom ratio (TPR20,10) for a square field of 10 x 10 cm2 and SDD of 100 cm. On some specialized radiotherapy treatment equipment such a reference collimator setting is not achievable. Likewise a flat beam profile, not explicitly required in dosimetry protocols, but certainly influences the measurement of Q, is not always produced. In this work, a method was developed in order to determine Q at any field size, especially for small and nonflattened beams. An analytical relationship was derived between TPR20,10 for arbitrary field sizes and Q [the TPR20,10 (10 x 10 cm2)] as quality index. The proposed model equation was fitted to the measured and published data in order to achieve three general fit parameters. The procedure was then tested with published data from TomoTherapy and CyperKnife treatment devices. For standard flattened photon fields, the uncertainty in Q measured at any field size using the parameters derived from this study is better than 1%. In flattening-filter free beams, the proposed procedure results in a reliable Q for any field size setting. A method is introduced and successfully tested in order to measure the beam quality under nonstandard conditions. It can be used, e.g., to get energy dependent correction factors as tabulated in dosimetry codes of practice even if standard conditions are not adjustable.

  16. GRAIN ALIGNMENT INDUCED BY RADIATIVE TORQUES: EFFECTS OF INTERNAL RELAXATION OF ENERGY AND COMPLEX RADIATION FIELD

    International Nuclear Information System (INIS)

    Hoang, Thiem; Lazarian, A.

    2009-01-01

    Earlier studies of grain alignment dealt mostly with interstellar grains that have strong internal relaxation of energy which aligns the grain axis of maximum moment of inertia (the axis of major inertia) with respect to the grain's angular momentum. In this paper, we study the alignment by radiative torques for large irregular grains, e.g., grains in accretion disks, for which internal relaxation is subdominant. We use both numerical calculations and the analytical model of a helical grain introduced by us earlier. We demonstrate that grains in such a regime exhibit more complex dynamics. In particular, if initially the grain axis of major inertia makes a small angle with angular momentum, then radiative torques can align the grain axis of major inertia with angular momentum, and both the axis of major inertia and angular momentum are aligned with the magnetic field when attractors with high angular momentum (high-J attractors) are available. For alignment without high-J attractors, beside the earlier studied attractors with low angular momentum (low-J attractors), there appear new low-J attractors. In addition, we also study the alignment of grains in the presence of strong internal relaxation, but induced not by a radiation beam as in earlier studies but instead induced by a complex radiation field that can be decomposed into dipole and quadrupole components. We found that in this situation the parameter space q max , for which high-J attractors exist in trajectory maps, is more extended, resulting in the higher degree of polarization expected. Our results are useful for modeling polarization arising from aligned dust grains in molecular clouds.

  17. Trapped-Ion Quantum Logic with Global Radiation Fields.

    Science.gov (United States)

    Weidt, S; Randall, J; Webster, S C; Lake, K; Webb, A E; Cohen, I; Navickas, T; Lekitsch, B; Retzker, A; Hensinger, W K

    2016-11-25

    Trapped ions are a promising tool for building a large-scale quantum computer. However, the number of required radiation fields for the realization of quantum gates in any proposed ion-based architecture scales with the number of ions within the quantum computer, posing a major obstacle when imagining a device with millions of ions. Here, we present a fundamentally different approach for trapped-ion quantum computing where this detrimental scaling vanishes. The method is based on individually controlled voltages applied to each logic gate location to facilitate the actual gate operation analogous to a traditional transistor architecture within a classical computer processor. To demonstrate the key principle of this approach we implement a versatile quantum gate method based on long-wavelength radiation and use this method to generate a maximally entangled state of two quantum engineered clock qubits with fidelity 0.985(12). This quantum gate also constitutes a simple-to-implement tool for quantum metrology, sensing, and simulation.

  18. Calibration of extremity dosemeters for gamma radiation fields

    International Nuclear Information System (INIS)

    Papadopulos, S.B.; Gregori, B.N.; Cruzate, J.A.

    1998-01-01

    In this work the kerma conversion factor are free in air, dose equivalent H(d,0 ) are presented, they were obtained theoretical and experimentally in finger and arm for gamma radiation fields. Extremity dosemeters put on surface finger and arm phantom have been irradiated. The finger phantom is a solid cylinder of PMMA polymethylmethacrylate 19 mm diameter and 300 mm height. The arm phantom is a 73 mm external diameter cylinder with PMMA walls 2.5 mm thick fill with water and 300 mm height. The radiation sources were cobalt 60 and cesium 137 from the Regional Center of Reference (CRR) of the National Commission of Atomic Energy (CNEA) and the Nuclear Regulatory Authority (ARN). Also in ISO wide X ray spectra W60, W110 and W200 have been irradiated. The results obtained show a good correlation with those published, they have a difference less than 7%. The factors will be applied to the evaluation of the equivalent doses coming from workers whose main irradiated zone is in the hands. (author)

  19. ARM West Antarctic Radiation Experiment (AWARE) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Lubin, Daniel [Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography; Bromwich, David H [Ohio State University; Vogelmann, Andrew M [Brookhaven National Lab. (BNL), Upton, NY (United States); Verlinde, Johannes [Pennsylvania State Univ., University Park, PA (United States); Russell, Lynn M [Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography

    2017-09-15

    The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE) is the most technologically advanced atmospheric and climate science campaign yet fielded in Antarctica. AWARE was motivated be recent concern about the impact of cryospheric mass loss on global sea level rise. Specifically, the West Antarctic Ice Sheet (WAIS) is now the second largest contributor to rising sea level, after the Greenland Ice Sheet. As steadily warming ocean water erodes the grounding lines of WAIS components where they meet the Amundsen and Bellingshausen Seas, the retreating grounding lines moving inland and downslope on the underlying terrain imply mechanical instability of the entire WAIS. There is evidence that this point of instability may have already been reached, perhaps signifying more rapid loss of WAIS ice mass. At the same time, the mechanical support provided by adjacent ice shelves, and also the fundamental stability of exposed ice cliffs at the ice sheet grounding lines, will be adversely impacted by a warming atmosphere that causes more frequent episodes of surface melting. The surface meltwater damages the ice shelves and ice cliffs through hydrofracturing. With the increasing concern regarding these rapid cryospheric changes, AWARE was motivated by the need to (a) diagnose the surface energy balance in West Antarctica as related to both summer season climatology and potential surface melting, and (b) improve global climate model (GCM) performance over Antarctica, such that future cryospheric projections can be more reliable.

  20. Ultrafast outflows disappear in high-radiation fields

    Science.gov (United States)

    Pinto, C.; Alston, W.; Parker, M. L.; Fabian, A. C.; Gallo, L. C.; Buisson, D. J. K.; Walton, D. J.; Kara, E.; Jiang, J.; Lohfink, A.; Reynolds, C. S.

    2018-05-01

    Ultrafast outflows (UFOs) are the most extreme winds launched by active galactic nuclei (AGN) due to their mildly relativistic speeds (˜0.1-0.3c) and are thought to significantly contribute to galactic evolution via AGN feedback. Their nature and launching mechanism are however not well understood. Recently, we have discovered the presence of a variable UFO in the narrow-line Seyfert 1 IRAS 13224-3809. The UFO varies in response to the brightness of the source. In this work we perform flux-resolved X-ray spectroscopy to study the variability of the UFO and found that the ionization parameter is correlated with the luminosity. In the brightest states the gas is almost completely ionized by the powerful radiation field and the UFO is hardly detected. This agrees with our recent results obtained with principal component analysis. We might have found the tip of the iceberg: the high ionization of the outflowing gas may explain why it is commonly difficult to detect UFOs in AGN and possibly suggest that we may underestimate their actual feedback. We have also found a tentative correlation between the outflow velocity and the luminosity, which is expected from theoretical predictions of radiation-pressure-driven winds. This trend is rather marginal due to the Fe XXV-XXVI degeneracy. Further work is needed to break such degeneracy through time-resolved spectroscopy.

  1. A Shared Compliance Control for Application in High Radiation Fields

    International Nuclear Information System (INIS)

    Ahn, Sung Ho; Jung, Hoan Sung; Lee, Kye Hong; Kim, Young Ki; Kim, Hark Rho

    2005-01-01

    Bilateral control systems present a technical alternative for intelligent robotic systems performing dexterous tasks in unstructured environments such as a nuclear facility, outer space and underwater. A shared compliance control scheme is proposed for application in high radiation fields in which the force sensor can not be installed because of a radiation effect. A position difference between the master system and the slave system is treated as an equivalent contact force and used for an input to the compliance controller. The compliance controller is implemented by a first order low pass filter and it modifies the position of the master to the reference position. Thus the compliance control task is shared by both the human operator's direct manual control and the autonomous compliance control of the slave system. Consequently, the position of a slave system tracks well the reference position and the compliance of the slave system is autonomously controlled in a contact condition. The simulation results show the excellence of the proposed scheme

  2. Optimum Water Chemistry in radiation field buildup control

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chien, C. [Vallecitos Nuclear Center, Pleasanton, CA (United States)

    1995-03-01

    Nuclear utilities continue to face the challenGE of reducing exposure of plant maintenance personnel. GE Nuclear Energy has developed the concept of Optimum Water Chemistry (OWC) to reduce the radiation field buildup and minimize the radioactive waste production. It is believed that reduction of radioactive sources and improvement of the water chemistry quality should significantly reduce both the radiation exposure and radwaste production. The most important source of radioactivity is cobalt and replacement of cobalt containing alloy in the core region as well as in the entire primary system is considered the first priority to achieve the goal of low exposure and minimized waste production. A plant specific computerized cobalt transport model has been developed to evaluate various options in a BWR system under specific conditions. Reduction of iron input and maintaining low ionic impurities in the coolant have been identified as two major tasks for operators. Addition of depleted zinc is a proven technique to reduce Co-60 in reactor water and on out-of-core piping surfaces. The effect of HWC on Co-60 transport in the primary system will also be discussed.

  3. An example of remote maintenance in high radiation fields

    International Nuclear Information System (INIS)

    Pothier, N.E.; Brisbois, L.U.

    Six auxiliary low pressure small (diameter <=5.0 cm) pipes located inside the reactor vault of the Douglas Point Nuclear Generating Station failed due to fretting wear at U-bolt supports: two had worn through the wall and developed leaks, and the others had worn <= 50% through the pipe wall. Human entry into the vault was not possible because of high radiation fields; hence, hands-on repair was not possible. The pipes were repaired and resupported to prevent further fretting wear failures during February-September, 1980. The repair work was performed using custom designed and developed remotely operated tooling and closed-circuit TV viewing. Three main groups were involved in the repair work: Atomic Energy of Canada Engineering Company (AECEC) - the reactor owner; Ontario Hydro - the reactor operator; and, Chalk River Nuclear Laboratories (CRNL). In this report, the contributions made by CRNL are summarized and discussed

  4. Theory of radiative transfer in a strong magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kanno, S [Ibaraki Univ., Mito (Japan). Dept. of Physics

    1975-07-01

    A theory is presented of the radiative transfer in a magnetized plasma with the opacity determined by the Thomson scattering. The Thomson cross section in the magnetic field is highly anisotropic and polarization-dependent. In order to cope with this situation, it is found useful to deal directly with the scattering amplitude (2x2 matrix in the polarization vector space) rather than the intensity. In this way it is possible to take into account the coherent superposition of the forward multiple-scattering amplitudes as a photon propagates. The equation of transfer is established accordingly and approximate solutions are found in the limits of small and large optical thickness. The latter solution is used to find the intensity and the polarization of thermal X-rays from a magnetic dipole star. The concept of mean free path is discussed and also it is shown that the Faraday rotation naturally comes about as a result of the multiple forward scattering.

  5. System decontamination as a tool to control radiation fields

    Energy Technology Data Exchange (ETDEWEB)

    Riess, R.; Bertholdt, H.O. [Siemens Power Generation Group, Erlangen (Germany)

    1995-03-01

    Since chemical decontamination of the Reactor Coolant Systems (RCS) and subsystems has the highest potential to reduce radiation fields in a short term this technology has gained an increasing importance. The available decontamination process at Siemens, i.e., the CORD processes, will be described. It is characterized by using permanganic acid for preoxidation and diluted organic acid for the decontamination step. It is a regenerative process resulting in very low waste volumes. This technology has been used frequently in Europe and Japan in both RCS and subsystems. An overview will be given i.e. on the 1993 applications. This overview will include plant, scope, date of performance, system volume specal features of the process removed activities, decon factor time, waste volumes, and personnel dose during decontamination. This overview will be followed by an outlook on future developments in this area.

  6. Highlights of IAEA activities in the field of radiation application

    International Nuclear Information System (INIS)

    Machi, S.

    1994-01-01

    In IAEA's major programme of Nuclear Applications, the activities performed are divided into four areas: food and agriculture, industry and earth science, human health, and physical and chemical sciences. These activities involve co-operation with FAO, WHO, UNIDO and UNEP, and have close link with the technical assistance programme. About 60% of the technical assistance projects are implemented in the field of nuclear applications. The purpose of the nuclear application programme is to develop technologies useful for environmental protection and sustainable development, to support R and D programmes of developing countries, to develop new applications of nuclear techniques. Major activities in food and agriculture are the application of radiation and isotopes, controling insects, preserving food, soil fertility and crop production, and improving animal production and the use of radiation with biotechnology for plant mutation breeding aiming at environmentally friendly and sustainable food production. In the human health programme emphasis is given to nuclear medicine, cancer therapy and nutrition. Today, only 35% of all developing countries have radiotherapy facilities. Activities, therefore, focus on strengthening clinical radiotherapy in such countries. In the field of industry and earth science, flue gas cleaning by electron beams, pollution monitoring using nuclear analytical techniques, nucleonic control systems for industries, and water resource exploration are major projects assisting developing countries. As of 1994 the IAEA will launch 12 new and promising Model Projects for developing Member States which will be of benefit to their economies and raising of their standard of living. In this paper the highlights of the above mentioned IAEA activities are presented. (author)

  7. Field test of a post-closure radiation monitor

    International Nuclear Information System (INIS)

    Reed, S.; Christy, C.E.; Heath, R.E.

    1995-01-01

    The DOE is conducting remedial actions at many sites contaminated with radioactive materials. After closure of these sites, long-term subsurface monitoring is typically required by law. This monitoring is generally labor intensive and expensive using conventional sampling and analysis techniques. The U.S. Department of Energy's Morgantown Energy Technology Center (METC) has contracted with Babcock and Wilcox to develop a Long-Term Post-Closure Radiation Monitoring System (LPRMS) to reduce these monitoring costs. A prototype LPRMS probe was built, and B ampersand W and FERMCO field tested this monitoring probe at the Fernald Environmental Management Project in the fall of 1994 with funding from the DOE's Office of Technology Development (EM-50) through METC. The system was used to measure soil and water with known uranium contamination levels, both in drums and in situ at depths up to 3 meters. For comparison purposes, measurements were also performed using a more conventional survey probe with a sodium iodide scintillator directly butt-coupled to detection electronics. This paper presents a description and the results of the field tests. The results were used to characterize the lower detection limits, precision and bias of the system, which allowed the DOE to judge the monitoring system's ability to meet its long-term post-closure radiation monitoring needs. Based on the test results, the monitoring system has been redesigned for fabrication and testing in a potential Phase III of this program. If the DOE feels that this system can meet its needs and chooses to continue into Phase III of this program, this redesigned full scale prototype system will be built and tested for a period of approximately a year. Such a system can be used at a variety of radioactively contaminated sites

  8. SU-E-T-813: What Is the “real” Field-Size in Photon Dosimetry?

    Energy Technology Data Exchange (ETDEWEB)

    Gainey, M; Kollefrath, M; Saum, R; Bruggmoser, G [University Medical Centre Freiburg, Freiburg Im Breisgau, Baden-Wuerttemberg (Germany)

    2015-06-15

    Purpose: The definition of field sizes in photon dosimetry and the measurement of profiles are non-trivial. Current definitions are nominal, geometric, dosimetric (actual) or equivalent field size. In reality most detectors are not water equivalent since they contain air or high density materials. These materials can blur profiles, particularly in small fields. If necessary, detector and field size-specific volume dependent effects need to be considered. Methods: A TrueBeam-linac (Varian Medical Systems) was used. All measurements were performed within a water phantom (MP3, PTW-Freiburg), with filter (WFF) and without filter (FFF), using ionization chambers, shielded and unshielded diodes and diamond detectors. The position of the jaws was verified according to our QA-system. Field size profiles were taken at a defined depth (SSD =90 cm, SCD=100 cm). The penumbra of the profiles measured with the various detectors was compared to determine the dosimetric field size. For the evaluation of the field sizes the inclination points were also calculated. Results: The field size, both for the WFF and the FFF-mode, coincided within 1 mm of the nominal field size. Due to the fact that the jaws were adjusted properly, the dosimetric field size coincides with the geometric field size. Exceptions are very small fields, where the dosimetric field size, defined by the inclination points, becomes broader than the geometric field size. Conclusion: Profiles, particularly of small fields, have to be measured very carefully using a suitable detector. For this purpose, a detector with a negligible volume correction factor should be used. The dosimetric field size can be found by evaluating the inclination points for both WFF and FFF beams. For dosimetric purposes it is necessary to find the dosimetric size. Alternatively, if the measurements are basic data for a TPS, both, the geometric and the dosimetric sizes should be recorded.

  9. SU-E-T-813: What Is the “real” Field-Size in Photon Dosimetry?

    International Nuclear Information System (INIS)

    Gainey, M; Kollefrath, M; Saum, R; Bruggmoser, G

    2015-01-01

    Purpose: The definition of field sizes in photon dosimetry and the measurement of profiles are non-trivial. Current definitions are nominal, geometric, dosimetric (actual) or equivalent field size. In reality most detectors are not water equivalent since they contain air or high density materials. These materials can blur profiles, particularly in small fields. If necessary, detector and field size-specific volume dependent effects need to be considered. Methods: A TrueBeam-linac (Varian Medical Systems) was used. All measurements were performed within a water phantom (MP3, PTW-Freiburg), with filter (WFF) and without filter (FFF), using ionization chambers, shielded and unshielded diodes and diamond detectors. The position of the jaws was verified according to our QA-system. Field size profiles were taken at a defined depth (SSD =90 cm, SCD=100 cm). The penumbra of the profiles measured with the various detectors was compared to determine the dosimetric field size. For the evaluation of the field sizes the inclination points were also calculated. Results: The field size, both for the WFF and the FFF-mode, coincided within 1 mm of the nominal field size. Due to the fact that the jaws were adjusted properly, the dosimetric field size coincides with the geometric field size. Exceptions are very small fields, where the dosimetric field size, defined by the inclination points, becomes broader than the geometric field size. Conclusion: Profiles, particularly of small fields, have to be measured very carefully using a suitable detector. For this purpose, a detector with a negligible volume correction factor should be used. The dosimetric field size can be found by evaluating the inclination points for both WFF and FFF beams. For dosimetric purposes it is necessary to find the dosimetric size. Alternatively, if the measurements are basic data for a TPS, both, the geometric and the dosimetric sizes should be recorded

  10. Finite size and dynamical effects in pair production by an external field

    International Nuclear Information System (INIS)

    Martin, C.; Vautherin, D.

    1988-12-01

    We evaluate the rate of pair production in a uniform electric field confined into a bounded region in space. Using the Balian-Bloch expansion of Green's functions we obtain explicit expressions for finite size corrections to Schwinger's formula. The case of a time-dependent boundary, relevant to describe energy deposition by quark-antiquark pair production in ultrarelativistic collisions, is also investigated. We find that finite size effects are important in nuclear collisions. They decrease when the strength of the chromo-electric field between the nuclei is large. As a result, the rate of energy deposition increases sharply with the mass number A of the colliding nuclei

  11. Questions concerning radiation protection in the field of radiometry

    International Nuclear Information System (INIS)

    Gruen, W.; Quednau, F.; Wels, Ch.

    1987-01-01

    Based on legal regulations, guidelines, and standards valid in the German Democratic Republic 105 questions concerning radiation protection are answered covering subjects indicated by the following key words and headings: radiometric gages, radiation protection measures, working within protected areas, legal provisions, responsible staff member, radiation protection officer, operating personnel, radiation protection instructions, safe keeping of radiation sources, leak testing, unusual occurrence, transport of radioactive materials, and ceasing of operation

  12. Situation in the radiation protection field in Costa Rica

    International Nuclear Information System (INIS)

    Pacheco Jimenez, R.E.

    2001-01-01

    The report describes the radiation protection infrastructure in Costa Rica and makes reference to the existing legal framework. The national inventory of significant radiation sources and structure of the Ministry of Health as the national regulatory authority for radiation safety is illustrated; information is also provided on the radiation monitoring equipment available, on programme activities related to the control of radiation sources by authorization and inspection, and on technical support services. (author)

  13. Combination transition radiation in a medium excited by an electromagnetic field

    International Nuclear Information System (INIS)

    Kalashnikova, Yu.S.

    1976-01-01

    The radiation emitted by a uniformly moving charged particle in a medium excited by an electromagnetic field is considered by taking into account the interaction between the electromagnetic waves and optical phonon wave. The frequencies are found, in the vicinity of which the two-wave approximation should be applied in order to determine the radiation field. It is shown that in the vicinity of these frequencies the radiation considerably differs from the Cherenkov radiation

  14. Hawking radiation of five-dimensional charged black holes with scalar fields

    Directory of Open Access Journals (Sweden)

    Yan-Gang Miao

    2017-09-01

    Full Text Available We investigate the Hawking radiation cascade from the five-dimensional charged black hole with a scalar field coupled to higher-order Euler densities in a conformally invariant manner. We give the semi-analytic calculation of greybody factors for the Hawking radiation. Our analysis shows that the Hawking radiation cascade from this five-dimensional black hole is extremely sparse. The charge enhances the sparsity of the Hawking radiation, while the conformally coupled scalar field reduces this sparsity.

  15. Numerical study on channel size effect for proton exchange membrane fuel cell with serpentine flow field

    International Nuclear Information System (INIS)

    Wang Xiaodong; Yan Weimon; Duan Yuanyuan; Weng Fangbor; Jung Guobin; Lee Chiyuan

    2010-01-01

    This work numerically investigates the effect of the channel size on the cell performance of proton exchange membrane (PEM) fuel cells with serpentine flow fields using a three-dimensional, two-phase model. The local current densities in the PEM, oxygen mass flow rates and liquid water concentrations at the interface of the cathode gas diffusion layer and catalyst layer were analyzed to understand the channel size effect. The predictions show that smaller channel sizes enhance liquid water removal and increase oxygen transport to the porous layers, which improve cell performance. Additionally, smaller channel sizes also provide more uniform current density distributions in the cell. However, as the channel size decreases, the total pressure drops across the cell increases, which leads to more pump work. With taking into account the pressure losses, the optimal cell performance occurs for a cell with a flow channel cross-sectional area of 0.535 x 0.535 mm 2 .

  16. Enhancement of grain size and crystallinity of thin layers of pentacene grown under magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Tabata, Kenichi [Division of Materials Science, Faculty of pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Yamamoto, Yohei, E-mail: yamamoto@ims.tsukuba.ac.jp [Division of Materials Science, Faculty of pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), Faculty of pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Center for Integrated Research in Fundamental Science and Technology (CiRfSE), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571 (Japan)

    2016-03-31

    Field-effect mobilities (μ) of pentacene films, prepared by a thermal deposition under a magnetic field (H-field), were largely enhanced, in comparison with that prepared without an H-field. Under a perpendicular H-field with respect to the substrate surface, the crystallinity of the edge-on pentacene orientation is enhanced, resulting in the 9-fold enhancement of μ. Furthermore, under parallel H-field with respect to the substrate surface, μ of the pentacene films were 23-fold greater than that prepared without the H-field. The surface morphology studies by atomic force microscopy of the ultra thin films of pentacene clarified that the grain size of the pentacene at the interface with the substrate is larger for films under parallel H-field than that prepared without an H-field. The simple and effective method for enhancing the semiconducting properties of the organic thin films gives high technological impact in its application to organic electronics. - Highlights: • Magnetic-field effect on the crystallinity of pentacene thin films • Magnetic-field effect on the morphology of pentacene thin films • Enhanced field-effect charge carrier mobility of pentacene thin films.

  17. Enhancement of grain size and crystallinity of thin layers of pentacene grown under magnetic field

    International Nuclear Information System (INIS)

    Tabata, Kenichi; Yamamoto, Yohei

    2016-01-01

    Field-effect mobilities (μ) of pentacene films, prepared by a thermal deposition under a magnetic field (H-field), were largely enhanced, in comparison with that prepared without an H-field. Under a perpendicular H-field with respect to the substrate surface, the crystallinity of the edge-on pentacene orientation is enhanced, resulting in the 9-fold enhancement of μ. Furthermore, under parallel H-field with respect to the substrate surface, μ of the pentacene films were 23-fold greater than that prepared without the H-field. The surface morphology studies by atomic force microscopy of the ultra thin films of pentacene clarified that the grain size of the pentacene at the interface with the substrate is larger for films under parallel H-field than that prepared without an H-field. The simple and effective method for enhancing the semiconducting properties of the organic thin films gives high technological impact in its application to organic electronics. - Highlights: • Magnetic-field effect on the crystallinity of pentacene thin films • Magnetic-field effect on the morphology of pentacene thin films • Enhanced field-effect charge carrier mobility of pentacene thin films

  18. Field transients of coherent terahertz synchrotron radiation accessed via time-resolving and correlation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Pohl, A.; Hübers, H.-W. [Humboldt-Universität zu Berlin, Institute of Physics, Newtonstraße 15, 12489 Berlin (Germany); Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 29, 12489 Berlin (Germany); Semenov, A. [Institute of Optical Sensor Systems, German Aerospace Center (DLR), Rutherfordstrasse 29, 12489 Berlin (Germany); Hoehl, A.; Ulm, G. [Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, 10587 Berlin (Germany); Ries, M.; Wüstefeld, G. [Helmholz-Zentrum Berlin, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Ilin, K.; Thoma, P.; Siegel, M. [Institute of Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology (KIT), Hertzstrasse 16, 76187 Karlsruhe (Germany)

    2016-03-21

    Decaying oscillations of the electric field in repetitive pulses of coherent synchrotron radiation in the terahertz frequency range was evaluated by means of time-resolving and correlation techniques. Comparative analysis of real-time voltage transients of the electrical response and interferograms, which were obtained with an ultrafast zero-bias Schottky diode detector and a Martin-Puplett interferometer, delivers close values of the pulse duration. Consistent results were obtained via the correlation technique with a pair of Golay Cell detectors and a pair of resonant polarisation-sensitive superconducting detectors integrated on one chip. The duration of terahertz synchrotron pulses does not closely correlate with the duration of single-cycle electric field expected for the varying size of electron bunches. We largely attribute the difference to the charge density oscillations in electron bunches and to the low-frequency spectral cut-off imposed by both the synchrotron beamline and the coupling optics of our detectors.

  19. TH-EF-204-02: Small Field Radiation Therapy: Physics and Recent Recommendations From IAEA and ICRU

    International Nuclear Information System (INIS)

    Seuntjens, J.

    2016-01-01

    Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment delivery systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to

  20. TH-EF-204-02: Small Field Radiation Therapy: Physics and Recent Recommendations From IAEA and ICRU

    Energy Technology Data Exchange (ETDEWEB)

    Seuntjens, J. [McGill University (Canada)

    2016-06-15

    Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment delivery systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to

  1. The wave properties of matter and the zeropoint radiation field

    International Nuclear Information System (INIS)

    Pena, L. de la; Cetto, A.M.

    1994-01-01

    The origin of the wave properties of matter is discussed from the point of view of stochastic electrodynamics. A nonrelativistic model of a changed particle with an effective structure embedded in the random zeropoint radiation field reveals that the field induces a high-frequency vibration on the particle; internal consistency of the theory fixes the frequency of this jittering at mc 2 /h. The particle is therefore assumed to interact intensely with stationary zeropoint waves of this frequency as seen from its proper frame of reference; such waves, identified here as de Broglie's phase waves, give rise to a modulated wave in the laboratory frame, with de Broglie's wavelength and phase velocity equal to the particle velocity. The time-independent equation that describes this modulated wave is shown to be the stationary Schroedinger equation (or the Klein-Gordon equation in the relativistic version). In a heuristic analysis applied to simple periodic cases, the quantization rules are recovered from the assumption that for a particle in a stationary state there must correspond a stationary modulation. Along an independent and complementary line of reasoning, an equation for the probability amplitude in configuration space for a particle under a general potential V(x) is constructed, and it is shown that under conditions derived from stochastic electrodynamics it reduces to Schroedinger's equation. This equation reflects therefore the dual nature of the quantum particles, by describing simultaneously the corresponding modulated wave and the ensemble of particles

  2. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    CERN Document Server

    Caresana, M; Esposito, A; Ferrarini, M; Golnik, N; Hohmann, E; Leuschner, A; Luszik-Bhadra, M; Manessi, G; Mayer, S; Ott, K; Röhrich, J; Silari, M; Trompier, F; Volnhals, M; Wielunski, M

    2014-01-01

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instru...

  3. Extractable proteins from field radiation vulcanized natural rubber latex

    Energy Technology Data Exchange (ETDEWEB)

    Parra, Duclerc F. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil)]. E-mail: dfparra@ipen.br; Pinto Martins, Carlos Felipe [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil); Collantes, Hugo D.C. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil); Lugao, Ademar B. [Chemical and Environmental Centre, Nuclear Energy Research Institute, Av. Lineu Prestes, 2242-CEP Sao Paulo (Brazil)

    2005-07-01

    The type I allergy associated with the use of natural rubber latex (NRL) products is caused by the NRL proteins leached by the sweat or other body fluids. Makuuchi's group proposed for the first time the proteins removal by the addition of water-soluble polymers (WSP) on radiation vulcanization of natural rubber latex (RVNRL) that is a promising process under development in many countries. In this study, Brazilian field natural rubber was irradiated with a {sup 60}Co gamma source to reduce the content of WSP in the final product. WSP was used as additive to improve the extraction of protein. After irradiation the RVNRL was centrifuged to extract the WSP and proteins. The analytical methodology for protein content was based on the modified Lowry method according to ASTM D5712. Protein determination was carried out in serum of latex and in the extracts of the gloves. The concentration of extractable water-soluble proteins in serum of irradiated field NRL (NRL1), not irradiated one (NRL2); of twice centrifuged sample with polymer additive NRL (NRL3) and of the glove manufactured (NRLG) are compared with commercial glove (CG). The irradiation process increases the extractable water-soluble proteins, EP, as reported in the literature. In this study the use of polymeric additive on the bi-centrifugation process to remove protein was successful and the EP of the glove obtained in NRL3 was at around 40% of the commercial glove.

  4. Near-Field Thermal Radiation for Solar Thermophotovoltaics and High Temperature Thermal Logic and Memory Applications

    Science.gov (United States)

    Elzouka, Mahmoud

    This dissertation investigates Near-Field Thermal Radiation (NFTR) applied to MEMS-based concentrated solar thermophotovoltaics (STPV) energy conversion and thermal memory and logics. NFTR is the exchange of thermal radiation energy at nano/microscale; when separation between the hot and cold objects is less than dominant radiation wavelength (˜1 mum). NFTR is particularly of interest to the above applications due to its high rate of energy transfer, exceeding the blackbody limit by orders of magnitude, and its strong dependence on separation gap size, surface nano/microstructure and material properties. Concentrated STPV system converts solar radiation to electricity using heat as an intermediary through a thermally coupled absorber/emitter, which causes STPV to have one of the highest solar-to-electricity conversion efficiency limits (85.4%). Modeling of a near-field concentrated STPV microsystem is carried out to investigate the use of STPV based solid-state energy conversion as high power density MEMS power generator. Numerical results for In 0.18Ga0.82Sb PV cell illuminated with tungsten emitter showed significant enhancement in energy transfer, resulting in output power densities as high as 60 W/cm2; 30 times higher than the equivalent far-field power density. On thermal computing, this dissertation demonstrates near-field heat transfer enabled high temperature NanoThermoMechanical memory and logics. Unlike electronics, NanoThermoMechanical memory and logic devices use heat instead of electricity to record and process data; hence they can operate in harsh environments where electronics typically fail. NanoThermoMechanical devices achieve memory and thermal rectification functions through the coupling of near-field thermal radiation and thermal expansion in microstructures, resulting in nonlinear heat transfer between two temperature terminals. Numerical modeling of a conceptual NanoThermoMechanical is carried out; results include the dynamic response under

  5. Accuracy of field alignment in abdominal radiation therapy

    International Nuclear Information System (INIS)

    Kortmann, R. D.; Hess, C. F.; Meisner, C.; Schmidberger, H.; Bamberg, M.

    1996-01-01

    Purpose: To assess the accuracy of field alignment in a homogeneous group of patients undergoing radiotherapy of the abdomen (adjuvant treatment of the paraaortic region in Stage I testicular seminoma). To evaluate the predictive value of the first verification on field placement errors during subsequent treatment delivery. Methods and Materials: In 45 patients, linear and rotational discrepancies were measured between simulation and first check and between 10 consecutive verification films. Results: For the total group of patients, the distribution of all deviations showed mean values between 2.3 mm and -2.7 mm with standard deviations of 3.9 mm to 4.7 mm for linear discrepancies, and -0.5 deg. to 0.3 deg. with standard deviations of 1.2 deg. to 2.1 deg. for rotational discrepancies, respectively. For all patients, deviations for the transition from simulator to the treatment machine were similar to deviations during subsequent treatment delivery, with 95% of all absolute deviations < 10.0 mm and 4 deg. , respectively. When performing correlation analysis between deviations at first check and during treatment delivery, a correlation for lateral displacements and a borderline correlation for caudal displacements could be found. There was no correlation for cranial and rotational displacements. Conclusions: Although a trend of deviations for subsequent treatment delivery may be shown at first check, our analysis indicates that the first verification cannot reliably predict inaccuracies during treatment delivery. Random fluctuations of field displacements of up to 1.0 cm prevail. They must be considered when prescribing the safety margins of the planned target volume and determining cutoff points for corrective actions in abdominal radiation therapy

  6. Thermoluminescent dependence with the particle size in ionized foods by radiation

    International Nuclear Information System (INIS)

    Teuffer Z, C.A.

    2005-01-01

    The influence of the particle size of poly minerals in the signals of the thermally stimulated luminescence (TL) is analysed. The poly minerals were extracted of Mexican spices such as Origanum vulgare L. (origanum) and Capsicum annum (Chilli guajillo), these underwent to an homogenization process to obtain four different particle sizes corresponding to 149, 74, 53 and 10 μ m, and later on to expose them to gamma radiation in an interval of 0.5- 45 kGy in the Gamma beam 651 PT of 60 Co irradiator of the Nuclear Sciences Institute, UNAM. The glow curves show a maximum of TL intensity for Capsicum annum to dose of 0.5- 10 kGy with particle size selected by means of a mesh of opening of 53 μ m, while for Origanum vulgare L., the more intense emission is observed with 149 μ m. In the interval of dose 12- 45 kGy the maximum in intensity emission it was presented in 53 μ m in both cases. For the case of 10 μ m, the TL emissions were of smaller intensity, and were achieved glow curves in a clear, defined way and an overlapping that allows to center the maximum of TL emission, in a defined temperature 126 C for Origanum vulgare L., and 166 C for Capsicum annum. The behavior before described is related with the composition of the samples. For Capsicum annum it was found Quartz (60%), Albite (30%) and Ortosa (10%), while Origanum vulgare stops L., Quartz (50%), Calcite (20%), Albite (20%) and Clay (10%). The homogenization of the samples is an important factor because exists high probability of avoiding as much as possible rests of organic matter traces that can contribute to the total signal of the glow curves. Likewise the defects that pollute from a natural way to each one of the minerals found in the samples, they play an outstanding role in the TL emissions. Although to the interacting the gamma radiation with the poly minerals of different particle sizes, there is a certain energy transfer that will be translated in the absorbed dose and this it will depend on the

  7. A stochastic simulation model for reliable PV system sizing providing for solar radiation fluctuations

    International Nuclear Information System (INIS)

    Kaplani, E.; Kaplanis, S.

    2012-01-01

    Highlights: ► Solar radiation data for European cities follow the Extreme Value or Weibull distribution. ► Simulation model for the sizing of SAPV systems based on energy balance and stochastic analysis. ► Simulation of PV Generator-Loads-Battery Storage System performance for all months. ► Minimum peak power and battery capacity required for reliable SAPV sizing for various European cities. ► Peak power and battery capacity reduced by more than 30% for operation 95% success rate. -- Abstract: The large fluctuations observed in the daily solar radiation profiles affect highly the reliability of the PV system sizing. Increasing the reliability of the PV system requires higher installed peak power (P m ) and larger battery storage capacity (C L ). This leads to increased costs, and makes PV technology less competitive. This research paper presents a new stochastic simulation model for stand-alone PV systems, developed to determine the minimum installed P m and C L for the PV system to be energy independent. The stochastic simulation model developed, makes use of knowledge acquired from an in-depth statistical analysis of the solar radiation data for the site, and simulates the energy delivered, the excess energy burnt, the load profiles and the state of charge of the battery system for the month the sizing is applied, and the PV system performance for the entire year. The simulation model provides the user with values for the autonomy factor d, simulating PV performance in order to determine the minimum P m and C L depending on the requirements of the application, i.e. operation with critical or non-critical loads. The model makes use of NASA’s Surface meteorology and Solar Energy database for the years 1990–2004 for various cities in Europe with a different climate. The results obtained with this new methodology indicate a substantial reduction in installed peak power and battery capacity, both for critical and non-critical operation, when compared to

  8. Visualization research of 3D radiation field based on Delaunay triangulation

    International Nuclear Information System (INIS)

    Xie Changji; Chen Yuqing; Li Shiting; Zhu Bo

    2011-01-01

    Based on the characteristics of the three dimensional partition, the triangulation of discrete date sets is improved by the method of point-by-point insertion. The discrete data for the radiation field by theoretical calculation or actual measurement is restructured, and the continuous distribution of the radiation field data is obtained. Finally, the 3D virtual scene of the nuclear facilities is built with the VR simulation techniques, and the visualization of the 3D radiation field is also achieved by the visualization mapping techniques. It is shown that the method combined VR and Delaunay triangulation could greatly improve the quality and efficiency of 3D radiation field visualization. (authors)

  9. Definition of datum of materials lump size on conveyors by means of reflected gamma-radiation method

    International Nuclear Information System (INIS)

    Gal'yanov, A.V.; Antonov, V.A.; Laptev, Yu.V.

    2001-01-01

    A method of technological control of large-size lumps in conveyor-transported crushed material based on intensity measurement of X-ray and gamma radiation reflected from the material surface was suggested. The method was substantiated theoretically and as a result it was shown that dispersion of radiation intensity, multiply measured for short periods of time, can be analytic parameter of large-size lumps yield. Principled methodical and design recommendations on the method practical applications are given [ru

  10. Simplified field-in-field technique for a large-scale implementation in breast radiation treatment

    International Nuclear Information System (INIS)

    Fournier-Bidoz, Nathalie; Kirova, Youlia M.; Campana, Francois; Dendale, Rémi; Fourquet, Alain

    2012-01-01

    We wanted to evaluate a simplified “field-in-field” technique (SFF) that was implemented in our department of Radiation Oncology for breast treatment. This study evaluated 15 consecutive patients treated with a simplified field in field technique after breast-conserving surgery for early-stage breast cancer. Radiotherapy consisted of whole-breast irradiation to the total dose of 50 Gy in 25 fractions, and a boost of 16 Gy in 8 fractions to the tumor bed. We compared dosimetric outcomes of SFF to state-of-the-art electronic surface compensation (ESC) with dynamic leaves. An analysis of early skin toxicity of a population of 15 patients was performed. The median volume receiving at least 95% of the prescribed dose was 763 mL (range, 347–1472) for SFF vs. 779 mL (range, 349–1494) for ESC. The median residual 107% isodose was 0.1 mL (range, 0–63) for SFF and 1.9 mL (range, 0–57) for ESC. Monitor units were on average 25% higher in ESC plans compared with SFF. No patient treated with SFF had acute side effects superior to grade 1-NCI scale. SFF created homogenous 3D dose distributions equivalent to electronic surface compensation with dynamic leaves. It allowed the integration of a forward planned concomitant tumor bed boost as an additional multileaf collimator subfield of the tangential fields. Compared with electronic surface compensation with dynamic leaves, shorter treatment times allowed better radiation protection to the patient. Low-grade acute toxicity evaluated weekly during treatment and 2 months after treatment completion justified the pursuit of this technique for all breast patients in our department.

  11. Changes in lymphocytes size under chronic exposure of the organism to factors of radiation and chemical origin

    International Nuclear Information System (INIS)

    Ivanov, V.V.

    1990-01-01

    Results of the analysis of changes in peripheral blood lymphocytes size under chronic exposure to external gamma radiation and pesticide chlorofoz in combination and separately are presented. It has been found out that under exposure of animals to radiation or the pesticide it is small and big lymphocytes respectively which most significantly suffer quantitatively. Under the joint radiational-chemical exposure of the organism the number of both types of cells is reduced simultaneously

  12. The Deep Physics Hidden within the Field Expressions of the Radiation Fields of Lightning Return Strokes

    Directory of Open Access Journals (Sweden)

    Vernon Cooray

    2016-01-01

    Full Text Available Based on the electromagnetic fields generated by a current pulse propagating from one point in space to another, a scenario that is frequently used to simulate return strokes in lightning flashes, it is shown that there is a deep physical connection between the electromagnetic energy dissipated by the system, the time over which this energy is dissipated and the charge associated with the current. For a given current pulse, the product of the energy dissipated and the time over which this energy is dissipated, defined as action in this paper, depends on the length of the channel, or the path, through which the current pulse is propagating. As the length of the channel varies, the action plotted against the length of the channel exhibits a maximum value. The location of the maximum value depends on the ratio of the length of the channel to the characteristic length of the current pulse. The latter is defined as the product of the duration of the current pulse and the speed of propagation of the current pulse. The magnitude of this maximum depends on the charge associated with the current pulse. The results show that when the charge associated with the current pulse approaches the electronic charge, the value of this maximum reaches a value close to h/8π where h is the Plank constant. From this result, one can deduce that the time-energy uncertainty principle is the reason for the fact that the smallest charge that can be detected from the electromagnetic radiation is equal to the electronic charge. Since any system that generates electromagnetic radiation can be represented by a current pulse propagating from one point in space to another, the result is deemed valid for electromagnetic radiation fields in general.

  13. Calculation of radiation field integrals for higher-order basis functions in conical thin wire MoM formulation

    CSIR Research Space (South Africa)

    Lysko, AA

    2008-07-01

    Full Text Available stream_source_info LyskoA_2008.pdf.txt stream_content_type text/plain stream_size 24096 Content-Encoding UTF-8 stream_name LyskoA_2008.pdf.txt Content-Type text/plain; charset=UTF-8 On Calculation of Radiation Field... recursive manner. The speed performance of a Matlab implementation indicates that the presented method is favorable compared to the commercial software “WIPL-D” used as a reference. Key-Words: - antenna radiation patterns, moment methods, numerical...

  14. Development of rubber material for high radiation field

    International Nuclear Information System (INIS)

    Nakatsukasa, Sadayoshi; Tabasaki, Takeshi; Yoshida, Akihiro; Kadowaki, Yoshito

    2013-01-01

    Generally flexible polymeric materials exposed to radiation can't be used because they soften or harden remarkably in high radiation environment. Aromatic polymers such as PEEK, PI, and PES are also known as radiation-proof polymeric materials. Aromatic polymers are very hard, they can't be used for products like a packing where flexibility is required. We developed a new vulcanized rubber compound by the use of various additives and polymer blend. This developed rubber compound has a high radiation-proof performance by reaction balance of cross-linking and decomposition in this rubber. This rubber compound has a rubber elasticity even if exposed to radiation of MGy level, and its radiation proof is more than 5 times as high as conventional polymeric materials. This rubber compound is much more flexible than the aromatic polymers which are the used as conventional radiation-proof polymers. (author)

  15. Studies of synthetic single crystal diamonds as reliable dosimeters for electromagnetic ionizing radiation fields

    International Nuclear Information System (INIS)

    Pillon, Mario; Angelone, Maurizio; Almaviva, Salvatore; Marinelli, Marco; Milani, Enrico; Prestopino, Giuseppe; Tucciarone, Aldo; Verona, Claudio; Verona-Rinati, Gianluca; Baccaro, Stefania

    2008-01-01

    Full text: Spatial high resolution dosimetry is very important in all areas of radiation therapy and, in particular, whenever narrow photon beams are required for Stereotactic Radiotherapy (SRT) and small field segments are used for Intensity Modulated Radiotherapy (IMRT). The available detectors are often too large with respect to the beam size considered, which is characterized by high dose gradients and lack of charged particle equilibrium. An ideal solution is represented by single crystal diamond detectors, which are small solid state devices, radiation hard, tissue equivalent and capable of real time response. In the present work, synthetic CVD single crystal diamond dosimeters (SCD), fabricated at Rome 'Tor Vergata' University Laboratories, have been characterized. The devices consist of a p-type/intrinsic/metal layered structure. They have been analyzed in terms of reproducibility, linearity, depth dose distributions, energy, dose rate and field size dependence by using 6 and 10 MV Bremsstrahlung x-ray beams, produced by a CLINAC DHX Varian accelerator and the gamma irradiation facility CALLIOPE. The gamma Calliope plant is a pool-type irradiation facility equipped with the 60 Co γ-source in a high-volume (7 x 6 x 3.9m 3 ). Maximum dose rate is 9400 Gy/h. The measurements have been compared with a calibrated ionization chamber and a Fricke dosimeter. The SCD's response is shown to be linearly correlated with the ionization chamber output over the whole dose range explored. Reproducibility, energy and dose rate dependency lower than 1% were observed. A depth dose distribution and irradiation field dependence in agreement with those obtained by reference dosimeters within 2% of accuracy were demonstrated as well. The results of this study are very encouraging about the suitability of SCD for clinical dosimetry with photon beams. (author)

  16. Protein crystallography with a micrometre-sized synchrotron-radiation beam

    International Nuclear Information System (INIS)

    Moukhametzianov, Rouslan; Burghammer, Manfred; Edwards, Patricia C.; Petitdemange, Sebastien; Popov, Dimitri; Fransen, Maikel; McMullan, Gregory; Schertler, Gebhard F. X.; Riekel, Christian

    2008-01-01

    For the first time, protein microcrystallography has been performed with a focused synchrotron-radiation beam of 1 µm using a goniometer with a sub-micrometre sphere of confusion. The crystal structure of xylanase II has been determined with a flux density of about 3 × 10 10 photons s −1 µm −2 at the sample. For the first time, protein microcrystallography has been performed with a focused synchrotron-radiation beam of 1 µm using a goniometer with a sub-micrometre sphere of confusion. The crystal structure of xylanase II has been determined with a flux density of about 3 × 10 10 photons s −1 µm −2 at the sample. Two sets of diffraction images collected from different sized crystals were shown to comprise data of good quality, which allowed a 1.5 Å resolution xylanase II structure to be obtained. The main conclusion of this experiment is that a high-resolution diffraction pattern can be obtained from 20 µm 3 crystal volume, corresponding to about 2 × 10 8 unit cells. Despite the high irradiation dose in this case, it was possible to obtain an excellent high-resolution map and it could be concluded from the individual atomic B-factor patterns that there was no evidence of significant radiation damage. The photoelectron escape from a narrow diffraction channel is a possible reason for reduced radiation damage as indicated by Monte Carlo simulations. These results open many new opportunities in scanning protein microcrystallography and make random data collection from microcrystals a real possibility, therefore enabling structures to be solved from much smaller crystals than previously anticipated as long as the crystallites are well ordered

  17. Sizes of X-ray radiation coherent domains in thin SmS films and their visualization

    Science.gov (United States)

    Sharenkova, N. V.; Kaminskii, V. V.; Petrov, S. N.

    2011-09-01

    The size of X-ray radiation coherent domains (250 ± 20 Å) is determined in a thin polycrystalline SmS film using X-ray diffraction patterns (θ-2θ scanning, DRON-2 diffractometer, Cu K α radiation) and the Selyakov-Scherrer formula with allowance for the effect of microstrains. An image of this film is taken with a transmission electron microscope, and regions with a characteristic size of 240 Å are clearly visible in it. It is concluded that X-ray radiation coherent domains are visualized.

  18. Characteristic of the radiation field in low earth orbit and in deep space

    International Nuclear Information System (INIS)

    Reitz, Guenther

    2008-01-01

    The radiation exposure in space by cosmic radiation can be reduced through careful mission planning and constructive measures as example the provision of a radiation shelter, but it cannot be completely avoided. The reason for that are the extreme high energies of particles in this field and the herewith connected high penetration depth in matter. For missions outside the magnetosphere ionizing radiation is recognized as the key factor through its impact on crew health and performance. In absence of sporadic solar particle events the radiation exposure in Low Earth orbit (LEO) inside Spacecraft is determined by the galactic cosmic radiation (protons and heavier ions) and by the protons inside the South Atlantic Anomaly (SAA), an area where the radiation belt comes closer to the earth surface due to a displacement of the magnetic dipole axes from the Earth's center. In addition there is an albedo source of neutrons produced as interaction products of the primary galactic particles with the atoms of the earth atmosphere. Outside the spacecraft the dose is dominated by the electrons of the horns of the radiation belt located at about 60 latitude in Polar Regions. The radiation field has spatial and temporal variations in dependence of the Earth magnetic field and the solar cycle. The complexity of the radiation field inside a spacecraft is further increased through the interaction of the high energy components with the spacecraft shielding material and with the body of the astronauts. In interplanetary missions the radiation belt will be crossed in a couple of minutes and therefore its contribution to their radiation exposure is quite small, but subsequently the protection by the Earth magnetic field is lost, leaving only shielding measures as exposure reduction means. The report intends to describe the radiation field in space, the interaction of the particles with the magnetic field and shielding material and give some numbers on the radiation exposure in low earth

  19. Characteristic of the radiation field in low Earth orbit and in deep space.

    Science.gov (United States)

    Reitz, Guenther

    2008-01-01

    The radiation exposure in space by cosmic radiation can be reduced through careful mission planning and constructive measures as example the provision of a radiation shelter, but it cannot be completely avoided. The reason for that are the extreme high energies of particles in this field and the herewith connected high penetration depth in matter. For missions outside the magnetosphere ionizing radiation is recognized as the key factor through its impact on crew health and performance. In absence of sporadic solar particle events the radiation exposure in Low Earth orbit (LEO) inside Spacecraft is determined by the galactic cosmic radiation (protons and heavier ions) and by the protons inside the South Atlantic Anomaly (SAA), an area where the radiation belt comes closer to the earth surface due to a displacement of the magnetic dipole axes from the Earth's center. In addition there is an albedo source of neutrons produced as interaction products of the primary galactic particles with the atoms of the earth atmosphere. Outside the spacecraft the dose is dominated by the electrons of the horns of the radiation belt located at about 60" latitude in Polar Regions. The radiation field has spatial and temporal variations in dependence of the Earth magnetic field and the solar cycle. The complexity of the radiation field inside a spacecraft is further increased through the interaction of the high energy components with the spacecraft shielding material and with the body of the astronauts. In interplanetary missions the radiation belt will be crossed in a couple of minutes and therefore its contribution to their radiation exposure is quite small, but subsequently the protection by the Earth magnetic field is lost, leaving only shielding measures as exposure reduction means. The report intends to describe the radiation field in space, the interaction of the particles with the magnetic field and shielding material and give some numbers on the radiation exposure in low earth

  20. Electron equilibrium for parallel plate ionization chambers in gamma radiation fields

    International Nuclear Information System (INIS)

    Caldas, L.; Albuquerque, M. da P.P.

    1989-08-01

    Parallel plate ionization chambers, designed and constructed for use in low energy X-radiation fields, were tested in gamma radiation beams ( 6 Co and 137 Cs) of two different Calibration Laboratories, in order to study the electron equilibrium occurrence and to verify the possibility of their use for the detection of the kind of radiation too. (author) [pt

  1. [C57BL/6 mice open field behaviour qualitatively depends on arena size].

    Science.gov (United States)

    Lebedev, I V; Pleskacheva, M G; Anokhin, K V

    2012-01-01

    Open field behavior is well known to depend on physical characteristics of the apparatus. However many of such effects are poorly described especially with using of modern methods of behavioral registration and analysis. The previous results of experiments on the effect of arena size on behavior are not numerous and contradictory. We compared the behavioral scores of four groups of C57BL/6 mice in round open field arenas of four different sizes (diameter 35, 75, 150 and 220 cm). The behavior was registered and analyzed using Noldus EthoVision, WinTrack and SegmentAnalyzer software. A significant effect of arena size was found. Traveled distance and velocity increased, but not in proportion to increase of arena size. Moreover a significant effect on segment characteristics of the trajectory was revealed. Detailed behavior analysis revealed drastic differences in trajectory structure and number of rears between smaller (35 and 75 cm) and bigger (150 and 220 cm) arenas. We conclude, that the character of exploration in smaller and bigger arenas depends on relative size of central open zone in arena. Apparently its extension increases the motivational heterogeneity of space, that requires another than in smaller arenas, strategy of exploration.

  2. Experimental study on infrared radiation temperature field of concrete under uniaxial compression

    Science.gov (United States)

    Lou, Quan; He, Xueqiu

    2018-05-01

    Infrared thermography, as a nondestructive, non-contact and real-time monitoring method, has great significance in assessing the stability of concrete structure and monitoring its failure. It is necessary to conduct in depth study on the mechanism and application of infrared radiation (IR) of concrete failure under loading. In this paper, the concrete specimens with size of 100 × 100 × 100 mm were adopted to carry out the uniaxial compressions for the IR tests. The distribution of IR temperatures (IRTs), surface topography of IRT field and the reconstructed IR images were studied. The results show that the IRT distribution follows the Gaussian distribution, and the R2 of Gaussian fitting changes along with the loading time. The abnormities of R2 and AE counts display the opposite variation trends. The surface topography of IRT field is similar to the hyperbolic paraboloid, which is related to the stress distribution in the sample. The R2 of hyperbolic paraboloid fitting presents an upward trend prior to the fracture which enables to change the IRT field significantly. This R2 has a sharp drop in response to this large destruction. The normalization images of IRT field, including the row and column normalization images, were proposed as auxiliary means to analyze the IRT field. The row and column normalization images respectively show the transverse and longitudinal distribution of the IRT field, and they have clear responses to the destruction occurring on the sample surface. In this paper, the new methods and quantitative index were proposed for the analysis of IRT field, which have some theoretical and instructive significance for the analysis of the characteristics of IRT field, as well as the monitoring of instability and failure for concrete structure.

  3. Patient size and x-ray technique factors in head computed tomography examinations. I. Radiation doses

    International Nuclear Information System (INIS)

    Huda, Walter; Lieberman, Kristin A.; Chang, Jack; Roskopf, Marsha L.

    2004-01-01

    We investigated how patient age, size and composition, together with the choice of x-ray technique factors, affect radiation doses in head computed tomography (CT) examinations. Head size dimensions, cross-sectional areas, and mean Hounsfield unit (HU) values were obtained from head CT images of 127 patients. For radiation dosimetry purposes patients were modeled as uniform cylinders of water. Dose computations were performed for 18x7 mm sections, scanned at a constant 340 mAs, for x-ray tube voltages ranging from 80 to 140 kV. Values of mean section dose, energy imparted, and effective dose were computed for patients ranging from the newborn to adults. There was a rapid growth of head size over the first two years, followed by a more modest increase of head size until the age of 18 or so. Newborns have a mean HU value of about 50 that monotonically increases with age over the first two decades of life. Average adult A-P and lateral dimensions were 186±8 mm and 147±8 mm, respectively, with an average HU value of 209±40. An infant head was found to be equivalent to a water cylinder with a radius of ∼60 mm, whereas an adult head had an equivalent radius 50% greater. Adult males head dimensions are about 5% larger than for females, and their average x-ray attenuation is ∼20 HU greater. For adult examinations performed at 120 kV, typical values were 32 mGy for the mean section dose, 105 mJ for the total energy imparted, and 0.64 mSv for the effective dose. Increasing the x-ray tube voltage from 80 to 140 kV increases patient doses by about a factor of 5. For the same technique factors, mean section doses in infants are 35% higher than in adults. Energy imparted for adults is 50% higher than for infants, but infant effective doses are four times higher than for adults. CT doses need to take into account patient age, head size, and composition as well as the selected x-ray technique factors

  4. Study of radiation dose reduction of buildings of different sizes and materials

    International Nuclear Information System (INIS)

    Furuta, Takuya; Takahashi, Fumiaki

    2015-01-01

    The dependence of radiation dose reduction on the sizes and materials of buildings was studied by numerical analyses using the Monte Carlo simulation code, PHITS. The dose rates inside the buildings were calculated by simulating gamma-ray transport from radioactive cesium deposited at the ground surface. Three building models were developed: the wooden house, the open-space concrete building, and the thin-wall building, to study the effect of building size and construction material on dose reduction inside these structures. Here the floor-area sizes of the building models were varied to clarify the influence of building configuration on dose reduction. The results demonstrated that the dose rates inside the buildings linearly decreased with increasing floor area on a logarithmic scale for all types of buildings considered. The calculated dose distribution inside a building indicated that the distance from the outer walls was a determining factor for the dose rate at each position in the building. The obtained tendency was verified by comparison with data reflecting the dose reduction of typical buildings in Japan. (author)

  5. Cell size dependence of additive versus synergetic effects of UV radiation and PAHs on oceanic phytoplankton

    International Nuclear Information System (INIS)

    Echeveste, Pedro; Agusti, Susana; Dachs, Jordi

    2011-01-01

    Polycyclic Aromatic Hydrocarbons' (PAHs) toxicity is enhanced by the presence of ultraviolet radiation (UVR), which levels have arisen due to the thinning of the ozone layer. In this study, PAHs' phototoxicity for natural marine phytoplankton was tested. Different concentrations of a mixture of 16 PAHs were added to natural phytoplankton communities from the Mediterranean Sea, Atlantic, Arctic and Southern Oceans and exposed to natural sunlight received in situ, including treatments where the UVR bands were removed. PAHs' toxicity was observed for all the phytoplankton groups studied in all the waters and treatments tested, but only for the pico-sized group a synergetic effect of the mixture and UVR was observed (p = 0.009). When comparing phototoxicity in phytoplankton from oligotrophic and eutrophic waters, synergy was only observed at the oligotrophic communities (p = 0.02) where pico-sized phytoplankton dominated. The degree of sensitivity was related to the trophic degree, decreasing as Chlorophyll a concentration increased. - Highlights: → The smallest picocyanobacteria were the most sensitive to PAHs and UVR. → PAHs-UVR synergism for the picophytoplankton and the oligotrophic communities. → PAHs-UVR additivity for the nanophytoplankton and the eutrophic communities. → An irradiance threshold is suggested to determine the joint action of UVR and PAHs. - Cell size and UVR levels determine additive/synergetic effects of PAHs and UVR to oceanic phytoplankton.

  6. Monte Carlo technique applications in field of radiation dosimetry at ENEA radiation protection institute: A Review

    International Nuclear Information System (INIS)

    Gualdrini, G.F.; Casalini, L.; Morelli, B.

    1994-12-01

    The present report summarizes the activities concerned with numerical dosimetry as carried out at the Radiation Protection Institute of ENEA (Italian Agency for New Technologies, Energy and the Environment) on photon dosimetric quantities. The first part is concerned with MCNP Monte Carlo calculation of field parameters and operational quantities for the ICRU sphere with reference photon beams for the design of personal dosemeters. The second part is related with studies on the ADAM anthropomorphic phantom using the SABRINA and MCNP codes. The results of other Monte Carlo studies carried out on electron conversion factors for various tissue equivalent slab phantoms are about to be published in other ENEA reports. The report has been produced in the framework of the EURADOS WG4 (numerical dosimetry) activities within a collaboration between the ENEA Environmental Department and ENEA Energy Department

  7. Vibration analysis and sound field characteristics of a tubular ultrasonic radiator.

    Science.gov (United States)

    Liang, Zhaofeng; Zhou, Guangping; Zhang, Yihui; Li, Zhengzhong; Lin, Shuyu

    2006-12-01

    A sort of tubular ultrasonic radiator used in ultrasonic liquid processing is studied. The frequency equation of the tubular radiator is derived, and its radiated sound field in cylindrical reactor is calculated using finite element method and recorded by means of aluminum foil erosion. The results indicate that sound field of tubular ultrasonic radiator in cylindrical reactor appears standing waves along both its radial direction and axial direction, and amplitudes of standing waves decrease gradually along its radial direction, and the numbers of standing waves along its axial direction are equal to the axial wave numbers of tubular radiator. The experimental results are in good agreement with calculated results.

  8. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats☆

    Science.gov (United States)

    Mohammed, Haitham S.; Fahmy, Heba M.; Radwan, Nasr M.; Elsayed, Anwar A.

    2012-01-01

    In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested. PMID:25685416

  9. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats

    Directory of Open Access Journals (Sweden)

    Haitham S. Mohammed

    2013-03-01

    Full Text Available In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day. EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS and rapid eye movement sleep (REM sleep revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested.

  10. Television imaging transducers for use in radiation fields

    International Nuclear Information System (INIS)

    Konyaev, V.M.; Krasovskij, S.S.; Surikov, I.N.

    1989-01-01

    For optical television equipment widely used in nuclear energetics it appears to be importance to account for various radiation effects on the device material and units aiming at diminishing negative effects of radiation upon the devices operation. Basing on the experimental results (along with the analysis of literature data) the authors propose a mechanism of radiation effect upon television imaging sensors (TIS). Operation principles and construction of up-to date TIS are briefly described, as well as the characteristics of radiation conditions. Various radiation effects upon the TIS material and construction have been considered. Optimal radiation conditions and levels have been suggested for the equipment operation. The efficiencies of various TIS are compared. 230 refs.; 86 figs.; 4 tabs

  11. Equivalent (uniform) square field sizes of flattening filter free photon beams

    Science.gov (United States)

    Lechner, Wolfgang; Kuess, Peter; Georg, Dietmar; Palmans, Hugo

    2017-10-01

    Various types of treatment units, such as CyberKnife, TomoTherapy and C-arm linear accelerators (LINACs) are operated using flattening filter free (FFF) photon beams. Their reference dosimetry, however, is currently based on codes of practice that provide data which were primarily developed and tested for high-energy photon beams with flattening filter (WFF). The aim of this work was to introduce equivalent uniform square field sizes of FFF beams to serve as a basis of a unified reference dosimetry procedure applicable to all aforementioned FFF machines. For this purpose, in-house determined experimental data together with published data of the ratio of doses at depths of 20 cm and 10 cm in water (D 20,10) were used to characterize the depth dose distribution of 6 and 10 MV WFF and FFF beams. These data were analyzed for field sizes ranging from 2  ×  2 cm2 to 40  ×  40 cm2. A scatter function that takes the lateral profiles of the individual beams into account was fitted to the experimental data. The lateral profiles of the WFF beams were assumed to be uniform, while those of the FFF beams were approximated using fourth or sixth order polynomials. The scatter functions of the FFF beams were recalculated using a uniform lateral profile (the same as the physical profile of the WFF beams), and are henceforth denoted as virtual uniform FFF beams (VUFFF). The field sizes of the VUFFF beams having the same scatter contribution as the corresponding FFF beams at a given field size were defined as the equivalent uniform square field (EQUSF) size. Data from four different LINACs with 18 different beams in total, as well as a CyberKnife beam, were analyzed. The average values of EQUSFs over all investigated LINACs of the conventional 10  ×  10 cm2 reference fields of 6 MV and 10 MV FFF beams for C-arm LINACs and machine-specific reference fields for CyberKnife and TomoTherapy were 9.5 cm, 9 cm, 5.0 cm and 6.5 cm respectively. The

  12. SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

    Energy Technology Data Exchange (ETDEWEB)

    Herchko, S; Ding, G [Vanderbilt University, Nashville, TN (United States)

    2016-06-15

    Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.

  13. SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

    International Nuclear Information System (INIS)

    Herchko, S; Ding, G

    2016-01-01

    Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.

  14. Utilization of radiation in industrial, agricultural and medical fields and its perspective

    International Nuclear Information System (INIS)

    Shibata, Tokushi

    2008-01-01

    The current status for the utilization of radiation in Japan was given from the view point of the economic scale. The topics which will be developed in near future such as lithography, radiation processing, radiation analysis in the industry, mutation breeding, sterile insect technique, food irradiation in agriculture, and radiation diagnosis, radiation therapy in medical field were presented. The important techniques for the further development of utilization of radiation will be the techniques related to the fabrication of semiconductor, developments of small accelerators and compact neutron generators. (author)

  15. Electromagnetic radiation of protons in edge fields of synchrotron dipole magnets

    International Nuclear Information System (INIS)

    Smolyakov, N.V.

    1986-01-01

    Effect of the edge shape of magnetic field of a dipole on the short-wave part of electromagnetic radiation spectrum of a proton beam is investigated. In some cases short-wave photons are shown to be shaped in the ranges of largest edge curvature of the magnetic field. Universality of edge radiation spectrum is proved. Spectral characteristics of proton edge radiation in a superconducting magnetic dipole of the storage-accelerator complex are obtained

  16. Use of the truncated shifted Pareto distribution in assessing size distribution of oil and gas fields

    Science.gov (United States)

    Houghton, J.C.

    1988-01-01

    The truncated shifted Pareto (TSP) distribution, a variant of the two-parameter Pareto distribution, in which one parameter is added to shift the distribution right and left and the right-hand side is truncated, is used to model size distributions of oil and gas fields for resource assessment. Assumptions about limits to the left-hand and right-hand side reduce the number of parameters to two. The TSP distribution has advantages over the more customary lognormal distribution because it has a simple analytic expression, allowing exact computation of several statistics of interest, has a "J-shape," and has more flexibility in the thickness of the right-hand tail. Oil field sizes from the Minnelusa play in the Powder River Basin, Wyoming and Montana, are used as a case study. Probability plotting procedures allow easy visualization of the fit and help the assessment. ?? 1988 International Association for Mathematical Geology.

  17. Comparative investigation of three dose rate meters for their viability in pulsed radiation fields

    International Nuclear Information System (INIS)

    Gotz, M; Karsch, L; Pawelke, J

    2015-01-01

    Pulsed radiation fields, characterized by microsecond pulse duration and correspondingly high pulse dose rates, are increasingly used in therapeutic, diagnostic and research applications. Yet, dose rate meters which are used to monitor radiation protection areas or to inspect radiation shielding are mostly designed, characterized and tested for continuous fields and show severe deficiencies in highly pulsed fields. Despite general awareness of the problem, knowledge of the specific limitations of individual instruments is very limited, complicating reliable measurements. We present here the results of testing three commercial dose rate meters, the RamION ionization chamber, the LB 1236-H proportional counter and the 6150AD-b scintillation counter, for their response in pulsed radiation fields of varied pulse dose and duration. Of these three the RamION proved reliable, operating in a pulsed radiation field within its specifications, while the other two instruments were only able to measure very limited pulse doses and pulse dose rates reliably. (paper)

  18. The size effect of the quantum coherence in the transverse-field XY chain

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lu; Yang, Cui-hong; Wang, Jun-feng [Department of Physics, Nanjing University of Information Science & Technology, Nanjing 210044 (China); Lei, Shu-guo, E-mail: sglei@njtech.edu.cn [College of Science, Nanjing Tech University, Nanjing, 211816 (China)

    2016-12-15

    Based on the Wigner–Yanase skew information, the size effect of the quantum coherence in the ground state of the finite transverse-field spin-1/2 XY chain is explored. It is found that the first-order derivatives of the single-spin coherence and the two-spin local coherence both have scaling behaviors in the vicinity of the critical point. A simplified version of coherence is also studied and the same characteristics with its counterpart are found.

  19. The influence of an extrapolation chamber over the low energy X-ray beam radiation field

    Energy Technology Data Exchange (ETDEWEB)

    Tanuri de F, M. T.; Da Silva, T. A., E-mail: mttf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Pampulha, Belo Horizonte, Minas Gerais (Brazil)

    2016-10-15

    The extrapolation chambers are detectors whose sensitive volume can be modified by changing the distance between the electrodes and has been widely used for beta particles primary measurement system. In this work, was performed a PTW 23392 extrapolation chamber Monte Carlo simulation, by mean the MCNPX code. Although the sensitive volume of an extrapolation chamber can be reduced to very small size, their packaging is large enough to modify the radiation field and change the absorbed dose measurements values. Experiments were performed to calculate correction factors for this purpose. The validation of the Monte Carlo model was done by comparing the spectra obtained with a CdTe detector according to the ISO 4037 criteria. Agreements smaller than 5% for half value layers, 10% for spectral resolution and 1% for mean energy, were found. It was verified that the correction factors are dependent of the X-ray beam quality. (Author)

  20. Radiation Field Forming for Industrial Electron Accelerators Using Rare-Earth Magnetic Materials

    Science.gov (United States)

    Ermakov, A. N.; Khankin, V. V.; Shvedunov, N. V.; Shvedunov, V. I.; Yurov, D. S.

    2016-09-01

    The article describes the radiation field forming system for industrial electron accelerators, which would have uniform distribution of linear charge density at the surface of an item being irradiated perpendicular to the direction of its motion. Its main element is non-linear quadrupole lens made with the use of rare-earth magnetic materials. The proposed system has a number of advantages over traditional beam scanning systems that use electromagnets, including easier product irradiation planning, lower instantaneous local dose rate, smaller size, lower cost. Provided are the calculation results for a 10 MeV industrial electron accelerator, as well as measurement results for current distribution in the prototype build based on calculations.

  1. The influence of an extrapolation chamber over the low energy X-ray beam radiation field

    International Nuclear Information System (INIS)

    Tanuri de F, M. T.; Da Silva, T. A.

    2016-10-01

    The extrapolation chambers are detectors whose sensitive volume can be modified by changing the distance between the electrodes and has been widely used for beta particles primary measurement system. In this work, was performed a PTW 23392 extrapolation chamber Monte Carlo simulation, by mean the MCNPX code. Although the sensitive volume of an extrapolation chamber can be reduced to very small size, their packaging is large enough to modify the radiation field and change the absorbed dose measurements values. Experiments were performed to calculate correction factors for this purpose. The validation of the Monte Carlo model was done by comparing the spectra obtained with a CdTe detector according to the ISO 4037 criteria. Agreements smaller than 5% for half value layers, 10% for spectral resolution and 1% for mean energy, were found. It was verified that the correction factors are dependent of the X-ray beam quality. (Author)

  2. Optimum field size and choice of isodose lines in electron beam treatment

    International Nuclear Information System (INIS)

    Das, Indra J.; Cheng, Chee W.; Healey, Glenn A.

    1995-01-01

    Purpose: A method is provided for the optimum field size and the choice of isodose line for the dose prescription in electron beam therapy. Methods and Materials: Electron beam dose uniformity was defined in terms of target coverage factor (TCF) which is an index of dose coverage of a given treatment volume. The TCF was studied with respect to the field size, the beam energy, and the isodose level for prescription from the measured data for various accelerators. The effect of the TCF on air gap between electron applicator/cone and the surface was investigated. Electron beams from scattering foil and scanned beam units were analyzed for the target coverage. Results: A mathematical method is provided to optimize a field size for target coverage by a given isodose line in terms of TCF which is strongly dependent on the type of accelerator and the design of the collimator. For a given type of collimating system, the TCF does not depend on the type of electron beam production (scattering foil or swept scanned beam). Selection of isodose line for dose prescription is very critical for the value of the TCF and the dose coverage. The TCF is inversely proportional to the isodose value selected for the treatment and nearly linear with field size and beam energy. Air gap between applicator and the surface reduces the dose uniformity. Tertiary collimator moderately improves the lateral coverage for high energy beams. Conclusions: To adequately cover the target volume in electron beam treatment, lateral and depth coverage should be considered. The coverage at depth is strongly dependent on the choice of isodose line or beam normalization. If the dose prescription is at d max (i.e., the 100% isodose line is selected), the choice of beam energy is not critical for depth coverage since d max is nearly independent of energy for smaller fields. The 100% isodose line should not be chosen for treatment because of the significant constriction of this isodose line and inadequate

  3. Nature of the Background Ultraviolet Radiation Field at High Redshifts

    Indian Academy of Sciences (India)

    tribpo

    J. Astrophys. Astr. (2000) 21, 19-27 .... to know the shape of the ionizing radiation to determine the ionization parameter from the C II to C IV ratio. ... different shapes of the background radiation spectrum as explained in the text. The solid lines.

  4. Nature of size effects in compact models of field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Torkhov, N. A., E-mail: trkf@mail.ru [Tomsk State University, Tomsk 634050 (Russian Federation); Scientific-Research Institute of Semiconductor Devices, Tomsk 634050 (Russian Federation); Tomsk State University of Control Systems and Radioelectronics, Tomsk 634050 (Russian Federation); Babak, L. I.; Kokolov, A. A.; Salnikov, A. S.; Dobush, I. M. [Tomsk State University of Control Systems and Radioelectronics, Tomsk 634050 (Russian Federation); Novikov, V. A., E-mail: novikovvadim@mail.ru; Ivonin, I. V. [Tomsk State University, Tomsk 634050 (Russian Federation)

    2016-03-07

    Investigations have shown that in the local approximation (for sizes L < 100 μm), AlGaN/GaN high electron mobility transistor (HEMT) structures satisfy to all properties of chaotic systems and can be described in the language of fractal geometry of fractional dimensions. For such objects, values of their electrophysical characteristics depend on the linear sizes of the examined regions, which explain the presence of the so-called size effects—dependences of the electrophysical and instrumental characteristics on the linear sizes of the active elements of semiconductor devices. In the present work, a relationship has been established for the linear model parameters of the equivalent circuit elements of internal transistors with fractal geometry of the heteroepitaxial structure manifested through a dependence of its relative electrophysical characteristics on the linear sizes of the examined surface areas. For the HEMTs, this implies dependences of their relative static (A/mm, mA/V/mm, Ω/mm, etc.) and microwave characteristics (W/mm) on the width d of the sink-source channel and on the number of sections n that leads to a nonlinear dependence of the retrieved parameter values of equivalent circuit elements of linear internal transistor models on n and d. Thus, it has been demonstrated that the size effects in semiconductors determined by the fractal geometry must be taken into account when investigating the properties of semiconductor objects on the levels less than the local approximation limit and designing and manufacturing field effect transistors. In general, the suggested approach allows a complex of problems to be solved on designing, optimizing, and retrieving the parameters of equivalent circuits of linear and nonlinear models of not only field effect transistors but also any arbitrary semiconductor devices with nonlinear instrumental characteristics.

  5. A stochastic-field description of finite-size spiking neural networks.

    Science.gov (United States)

    Dumont, Grégory; Payeur, Alexandre; Longtin, André

    2017-08-01

    Neural network dynamics are governed by the interaction of spiking neurons. Stochastic aspects of single-neuron dynamics propagate up to the network level and shape the dynamical and informational properties of the population. Mean-field models of population activity disregard the finite-size stochastic fluctuations of network dynamics and thus offer a deterministic description of the system. Here, we derive a stochastic partial differential equation (SPDE) describing the temporal evolution of the finite-size refractory density, which represents the proportion of neurons in a given refractory state at any given time. The population activity-the density of active neurons per unit time-is easily extracted from this refractory density. The SPDE includes finite-size effects through a two-dimensional Gaussian white noise that acts both in time and along the refractory dimension. For an infinite number of neurons the standard mean-field theory is recovered. A discretization of the SPDE along its characteristic curves allows direct simulations of the activity of large but finite spiking networks; this constitutes the main advantage of our approach. Linearizing the SPDE with respect to the deterministic asynchronous state allows the theoretical investigation of finite-size activity fluctuations. In particular, analytical expressions for the power spectrum and autocorrelation of activity fluctuations are obtained. Moreover, our approach can be adapted to incorporate multiple interacting populations and quasi-renewal single-neuron dynamics.

  6. Momentum accumulation due to solar radiation torque, and reaction wheel sizing, with configuration optimization

    Science.gov (United States)

    Hablani, Hari B.

    1993-01-01

    This paper has a two-fold objective: determination of yearly momentum accumulation due to solar radiation pressure, and optimum reaction wheel sizing. The first objective is confronted while determining propellant consumption by the attitude control system over a spacecraft's lifetime. This, however, cannot be obtained from the daily momentum accumulation and treating that constant throughout the year, because the orientation of the solar arrays relative to the spacecraft changes over a wide range in a year, particularly if the spacecraft has two arrays, one normal and the other off-normal to different extent at different times to the sun rays. The paper first develops commands for the arrays for tracking the sun, the arrays articulated to earth-pointing spacecraft with two rotational degrees of freedom, and spacecraft in an arbitrary circular orbit. After developing expressions for solar radiation torque due to one or both arrays, arranged symmetrically or asymmetrically relative to the spacecraft bus, momentum accumulation over an orbit and then over a year are determined. The remainder of the paper is concerned with designing reaction wheel configurations. Four-, six-, and three-wheel configurations are considered, and for given torque and momentum requirements, their cant angles with the roll/yaw plane are optimized for minimum power consumption. Finally, their momentum and torque capacities are determined for one-wheel failure scenario, and six configurations are compared and contrasted.

  7. Electromagnetic radiation damping of charges in external gravitational fields (weak field, slow motion approximation). [Harmonic coordinates, weak field slow-motion approximation, Green function

    Energy Technology Data Exchange (ETDEWEB)

    Rudolph, E [Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (F.R. Germany)

    1975-01-01

    As a model for gravitational radiation damping of a planet the electromagnetic radiation damping of an extended charged body moving in an external gravitational field is calculated in harmonic coordinates using a weak field, slowing-motion approximation. Special attention is paid to the case where this gravitational field is a weak Schwarzschild field. Using Green's function methods for this purpose it is shown that in a slow-motion approximation there is a strange connection between the tail part and the sharp part: radiation reaction terms of the tail part can cancel corresponding terms of the sharp part. Due to this cancelling mechanism the lowest order electromagnetic radiation damping force in an external gravitational field in harmonic coordinates remains the flat space Abraham Lorentz force. It is demonstrated in this simplified model that a naive slow-motion approximation may easily lead to divergent higher order terms. It is shown that this difficulty does not arise up to the considered order.

  8. The field measurements of the activity-weighted size distributions of radon decay products

    International Nuclear Information System (INIS)

    Wasiolek, P.; Montassier, N.; Hopke, P.K.

    1991-01-01

    Because of the importance of particle size in the calculations of dose deposited in the respiratory tract by radon progeny, the determination of the size distribution of radon decay products in indoor air had increased in interest in recent years. A system for the measurement of the activity-weighted size distribution of radon decay products at environmental levels has been developed. The system (ASC-GSA) utilizes a combination of six multiple wire screens (Graded Screen Array) sampler detector units operated in parallel. The cut off points of the samplers and the data deconvolution procedure allow to obtain the activity fractions of radon progeny in the size range 0.5-500 mn. The computer control of sampling, alpha counting and data storage permits the operation of the system on the semi-continuous basis. The primary application of the ASC-GSA system has been to collect data of activity-weighted size distributions of radon progeny in real house environments. The results of field measurements in several houses with elevated radon levels are presented

  9. Influence of dose on particle size of colloidal silver nanoparticles synthesized by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Naghavi, Kazem, E-mail: Kazem.naghavi@gmail.co [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia); Saion, Elias [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia); Rezaee, Khadijeh [Department of Nuclear Engineering, Faculty of Modern Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Yunus, Wan Mahmood Mat [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia)

    2010-12-15

    Colloidal silver nanoparticles were synthesized by {gamma}-irradiation-induced reduction method of an aqueous solution containing silver nitrate as a precursor in various concentrations between 7.40x10{sup -4} and 1.84x10{sup -3} M, polyvinyl pyrrolidone for capping colloidal nanoparticles, isopropanol as radical scavenger of hydroxyl radicals and deionised water as a solvent. The irradiations were carried out in a {sup 60}Co {gamma} source chamber at doses up to 70 kGy. The optical absorption spectra were measured using UV-vis spectrophotometer and used to study the particle distribution and electronic structure of silver nanoparticles. As the radiation dose increases from 10 to 70 kGy, the absorption intensity increases with increasing dose. The absorption peak {lambda}{sub max} blue shifted from 410 to 403 nm correspond to the increase of absorption conduction electron energy from 3.02 to 3.08 eV, indicating the particle size decreases with increasing dose. The particle size was determined by photon cross correlation spectroscopy and the results showed that the particle diameter decreases exponentially with the increase of dose. The transmission electron microscopy images were taken at doses of 20 and 60 kGy and the results confirmed that as the dose increases the diameter of colloidal silver nanoparticle decreases and the particle distribution increases.

  10. Influence of dose on particle size of colloidal silver nanoparticles synthesized by gamma radiation

    International Nuclear Information System (INIS)

    Naghavi, Kazem; Saion, Elias; Rezaee, Khadijeh; Yunus, Wan Mahmood Mat

    2010-01-01

    Colloidal silver nanoparticles were synthesized by γ-irradiation-induced reduction method of an aqueous solution containing silver nitrate as a precursor in various concentrations between 7.40x10 -4 and 1.84x10 -3 M, polyvinyl pyrrolidone for capping colloidal nanoparticles, isopropanol as radical scavenger of hydroxyl radicals and deionised water as a solvent. The irradiations were carried out in a 60 Co γ source chamber at doses up to 70 kGy. The optical absorption spectra were measured using UV-vis spectrophotometer and used to study the particle distribution and electronic structure of silver nanoparticles. As the radiation dose increases from 10 to 70 kGy, the absorption intensity increases with increasing dose. The absorption peak λ max blue shifted from 410 to 403 nm correspond to the increase of absorption conduction electron energy from 3.02 to 3.08 eV, indicating the particle size decreases with increasing dose. The particle size was determined by photon cross correlation spectroscopy and the results showed that the particle diameter decreases exponentially with the increase of dose. The transmission electron microscopy images were taken at doses of 20 and 60 kGy and the results confirmed that as the dose increases the diameter of colloidal silver nanoparticle decreases and the particle distribution increases.

  11. Effect of particle size of mineral fillers on polymer-matrix composite shielding materials against ionizing electromagnetic radiation

    International Nuclear Information System (INIS)

    Belgin, E.E.; Aycik, G.A.

    2017-01-01

    Filler particle size is an important particle that effects radiation attenuation performance of a composite shielding material but the effects of it have not been exploited so far. In this study, two mineral (hematite-ilmenite) with different particle sizes were used as fillers in a polymer-matrix composite and effects of particle size on shielding performance was investigated within a widerange of radiation energy (0-2000 keV). The thermal and structural properties of the composites were also examined. The results showed that as the filler particle size decreased the shielding performance increased. The highest shielding performance reached was 23% with particle sizes being between <7 and <74 µm. (author)

  12. TLD DRD dose discrepancy: role of beta radiation fields

    International Nuclear Information System (INIS)

    Munish Kumar; Pradhan, S.M.; Bihari, R.R.; Bakshi, A.K.; Chougaonkar, M.P.; Babu, D.A.R.; Gupta, Anil

    2014-01-01

    Ionization chamber based direct reading/pocket dosimeters (DRDs), are used along with the legal dosimeters (thermoluminescent dosimeters-TLDs) for day to day monitoring and control of radiation doses received by radiation workers. The DRDs are routinely used along with the passive dosimeters (TLDs) in nuclear industry at different radiation installations where radiation levels could vary significantly and the possibility of receiving doses beyond investigation levels by radiation workers is not ruled out. Recently, recommendations for dealing with discrepancies between personal dosimeter systems used in parallel were issued by ISO. The present study was performed to measure the response of ionization chamber based pocket dosimeters to various beta sources having energy (E max ) ranging from 0.224 MeV-3.54 MeV. It is expected that the above study will be useful in resolving the disparity between TLD and DRD doses at those radiation installations where radiation workers are likely to be exposed simultaneously from photons and beta particles

  13. Countermeasure for terrorism-new field of radiation protection

    International Nuclear Information System (INIS)

    Ye Changqing

    2003-01-01

    The workers on radiation protection have been confronted with a new task-countering terrorism. The description and level of various threats threats, the potential consequences and occurrence probability of different nuclear and radiation attack events, and the responses to these threats (crisis and consequence) are introduced at two levels. At the level of crisis management, some approaches to mitigation, the works done by International Atomic Energy Agency and the tendency in United States are also presented. At the level of consequence management, the essential practices submitted by National Council on Radiation Protection and Measurements of America are listed. Finally the domest ic progress in this area is introduced too. (authors)

  14. HOTSPOT, Field Evaluation of Radiation Release from Nuclear Accident

    International Nuclear Information System (INIS)

    2001-01-01

    1 - Description of program or function: The HOTSPOT Health Physics codes were created to provide Health Physics personnel with a fast, field-portable calculational tool for evaluating accidents involving radioactive materials. HOTSPOT codes are a first-order approximation of the radiation effects associated with the atmospheric release of radioactive materials. HOTSPOT programs are reasonably accurate for a timely initial assessment. More importantly, HOTSPOT codes produce a consistent output for the same input assumptions and minimize the probability of errors associated with reading a graph incorrectly or scaling a universal nomogram during an emergency. Four general programs, PLUME, EXPLOSION, FIRE, and RESUSPENSION, calculate a downwind assessment following the release of radioactive material resulting from a continuous or puff release, explosive release, fuel fire, or an area contamination event. Other programs deal with the release of plutonium, uranium, and tritium to expedite an initial assessment of accidents involving nuclear weapons. Additional programs estimate the dose commitment from inhalation of any one of the radionuclides listed in the database of radionuclides, calibrate a radiation survey instrument for ground survey measurements, and screening of plutonium uptake in the lung. The HOTSPOT codes are fast, portable, easy to use, and fully documented. HOTSPOT supports color high resolution monitors and printers for concentration plots and contours. The codes have been extensively used by the DOS community since 1985. Version 8 allows users to add their own custom radionuclide library and to create custom radionuclide mixtures. It also includes wet deposition to approximate the enhanced plume depletion and ground deposition due to the effects of rain. Additional release geometry options for TRITIUM RELEASE and GENERAL PLUME were added, as well as several other enhancements and improvements. See info (f1) from the main HOTSPOT menu for additional

  15. Characterisation of ionisation chambers for a mixed radiation field and investigation of their suitability as radiation monitors for the LHC.

    Science.gov (United States)

    Theis, C; Forkel-Wirth, D; Perrin, D; Roesler, S; Vincke, H

    2005-01-01

    Monitoring of the radiation environment is one of the key tasks in operating a high-energy accelerator such as the Large Hadron Collider (LHC). The radiation fields consist of neutrons, charged hadrons as well as photons and electrons with energy spectra extending from those of thermal neutrons up to several hundreds of GeV. The requirements for measuring the dose equivalent in such a field are different from standard uses and it is thus necessary to investigate the response of monitoring devices thoroughly before the implementation of a monitoring system can be conducted. For the LHC, it is currently foreseen to install argon- and hydrogen-filled high-pressure ionisation chambers as radiation monitors of mixed fields. So far their response to these fields was poorly understood and, therefore, further investigation was necessary to prove that they can serve their function well enough. In this study, ionisation chambers of type IG5 (Centronic Ltd) were characterised by simulating their response functions by means of detailed FLUKA calculations as well as by calibration measurements for photons and neutrons at fixed energies. The latter results were used to obtain a better understanding and validation of the FLUKA simulations. Tests were also conducted at the CERF facility at CERN in order to compare the results with simulations of the response in a mixed radiation field. It is demonstrated that these detectors can be characterised sufficiently enough to serve their function as radiation monitors for the LHC.

  16. Normal Threshold Size of Stimuli in Children Using a Game-Based Visual Field Test.

    Science.gov (United States)

    Wang, Yanfang; Ali, Zaria; Subramani, Siddharth; Biswas, Susmito; Fenerty, Cecilia; Henson, David B; Aslam, Tariq

    2017-06-01

    The aim of this study was to demonstrate and explore the ability of novel game-based perimetry to establish normal visual field thresholds in children. One hundred and eighteen children (aged 8.0 ± 2.8 years old) with no history of visual field loss or significant medical history were recruited. Each child had one eye tested using a game-based visual field test 'Caspar's Castle' at four retinal locations 12.7° (N = 118) from fixation. Thresholds were established repeatedly using up/down staircase algorithms with stimuli of varying diameter (luminance 20 cd/m 2 , duration 200 ms, background luminance 10 cd/m 2 ). Relationships between threshold and age were determined along with measures of intra- and intersubject variability. The Game-based visual field test was able to establish threshold estimates in the full range of children tested. Threshold size reduced with increasing age in children. Intrasubject variability and intersubject variability were inversely related to age in children. Normal visual field thresholds were established for specific locations in children using a novel game-based visual field test. These could be used as a foundation for developing a game-based perimetry screening test for children.

  17. Experimental study on the luminous radiation associated to the field emission of samples submitted to high RF fields

    International Nuclear Information System (INIS)

    Maissa, S.; Junquera, T.; Fouaidy, M.; Le Goff, A.; Luong, M.; Tan, J.; Bonin, B.; Safa, H.

    1996-01-01

    Nowadays the accelerating gradient of the RF cavities is limited by the strong field emission (FE) of electrons stemming from the metallic walls. Previous experiments evidenced luminous radiations associated with electron emission on cathodes subjected to intense DC electric field. These observations led these authors to propose new theoretical models of the field emission phenomenon. The presented experimental study extends these previous DC works to the RF case. A special copper RF cavity has been developed equipped with an optical window and a removable sample. It has been designed for measuring both electron current and luminous radiation emitted by the sample, subjected to maximum RF electric field. The optical apparatus attached to the cavity permits to characterize the radiation in terms of intensity, glowing duration and spectral distribution. The results concerning different niobium or copper samples, whom top was either scratched or intentionally contaminated with metallic or dielectric particles are summarized. (author)

  18. Experimental study on the luminous radiation associated to the field emission of samples submitted to high RF fields

    International Nuclear Information System (INIS)

    Maissa, S.; Junquera, T.; Fouaidy, M.; Le Goff, A.; Luong, M.; Tan, J.; Bonin, B.; Safa, H.

    1996-01-01

    The accelerating gradient of the RF cavities is limited by the strong field emission (FE) of electrons stemming from the metallic walls. Previous experiments evidenced luminous radiations associated with electron emission of cathodes subjected to intense DC electric field. These observations invoked the proposal of new theoretical models of the field emission phenomenon. This experimental study extends the previous DC works to the RF case. A special copper RF cavity has been developed equipped with an optical window and a removable sample. It has been designed for measuring both electron current and luminous radiation emitted by the sample, subjected to maximum RF electric field. The optical apparatus attached to the cavity permits to characterize the radiation in terms of intensity, glowing duration and spectral distribution. The results concerning different niobium or copper samples, whom top was either scratched or intentionally contaminated with metallic or dielectric particles are summarized. (author)

  19. Particle size reduction in debris flows: Laboratory experiments compared with field data from Inyo Creek, California

    Science.gov (United States)

    Arabnia, O.; Sklar, L. S.; Mclaughlin, M. K.

    2014-12-01

    . Laboratory data are compared with longitudinal evolution of grain size and angularity of particles deposited by debris flows along Inyo Creek, Sierra Nevada, California. Preliminary results suggest wear rates can be scaled across drum sizes and to field conditions using non-dimensional metrics of flow dynamics including Savage, Bagnold, and Froude numbers.

  20. Asymmetric active nano-particles for directive near-field radiation

    DEFF Research Database (Denmark)

    Arslanagic, Samel; Thorsen, Rasmus O.

    2016-01-01

    In this work, we demonstrate the potential of cylindrical active coated nano-particles with certain geometrical asymmetries for the creation of directive near-field radiation. The particles are excited by a near-by magnetic line source, and their performance characteristics are reported in terms...... of radiated power, near-field and power flow distributions as well as the far-field directivity....

  1. Measurement and calculation of radiation fields of the Sandia irradiator for dried sewage solids

    International Nuclear Information System (INIS)

    Morris, M.E.

    1981-03-01

    The radiation field of the Sandia Irradiator for Dried Sewage Solids was measured. The results of the measurement are given in this report. In addition, theoretical calculations of the fields are given and then compared with the measured values. Elementary models of the radiation source geometry and irradiated product are found to be adequate and thus allow us to duplicate (through calculation) the important features of the measured fields

  2. Moessbauer radiation dynamical diffraction in crystals being subjected to the action of external variable fields

    International Nuclear Information System (INIS)

    Baryshevskii, V.G.; Skadorov, V.V.

    1986-01-01

    A dynamical theory is developed of the Moessbauer radiation diffraction by crystals being subjected to an variable external field action. Equations describing the dynamical diffraction by nonstationary crystals are obtained. It is shown that the resonant interaction between Moessbauer radiation and shift field induced in the crystal by a variable external field giving rise to an effective conversion of the incident wave into a wave with changed frequency. (author)

  3. Optimal sample size of signs for classification of radiational and oily soils

    International Nuclear Information System (INIS)

    Babayev, M.P.; Iskenderov, S.M.; Aghayev, R.A.

    2012-01-01

    Full text : This article tells about classification of radiational and oily soils that should be in essence a compact intelligence system which contains maximum information on classes of soil objects in the accepted feature space. The stored experience shows that the volume of the most informative soil signs can make up maximum 7-8 indexes. More correct approach to our opinion for a sample of the most informative (most important) indexes is the method of testing and mistakes, that is the experimental method, allowing to make use a wide experience and intuition of the researcher, or group of the researchers, engaged for many years in the field of soil science. At this operational stage of the formal device of soils classification, to say more concrete, the assessment section of selfdescriptiveness of soil signs of this formal device, in our opinion, is purely mathematized and in some cases even not reflect the true picture. In this case it will be calculated 21 pair of correlative elements between the selected soil signs as a measure of the linear communication. The volume of the correlative row will be equal to 6, as the increase in volume of the correlative row can sharply increase the volume calculation. Pertinently to note that, it is the first time an attempt is made to create correlative matrixes of the most important signs of radiation and oily soils

  4. CONCORD: comparison of cosmic radiation detectors in the radiation field at aviation altitudes

    Czech Academy of Sciences Publication Activity Database

    Meier, M.; Trompier, F.; Ambrožová, Iva; Kubančák, Ján; Matthia, D.; Ploc, Ondřej; Santen, N.; Wirtz, M.

    2016-01-01

    Roč. 6, MAY (2016), A24 ISSN 2115-7251 Institutional support: RVO:61389005 Keywords : aviation * radiation exposure of aircrew * comparison of radiation detectors * galactic cosmic radiation * ambient dose equivalent Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.446, year: 2016

  5. Calculation of radiation fields for Hanford tank riser modifications

    International Nuclear Information System (INIS)

    Schwarz, R.A.; Carter, L.L.; Hillesland, K.E.

    1994-10-01

    A visualization process has been created to animate the dose rates from radiation sources as the source and shielding configuration are modified. This process has been illustrated with the removal of a mixer pump from a Hanford Site waste tank

  6. Radiation hygiene aspects of mixed neutron-gamma field dosimetry

    International Nuclear Information System (INIS)

    Nikodemova, O.; Hrabovcova, A.

    1982-01-01

    Various possibilities are analyzed of determining the dose equivalent of neutrons, as is the reliability of the techniques and the correct interpretation for the purposes of radiation hygiene. (author)

  7. Computational radiation chemistry: the emergence of a new field

    International Nuclear Information System (INIS)

    Bartczak, W.M.; Kroh, J.

    1991-01-01

    The role of the computer experiment as an information source, which is complementary to the ''real'' experiment in radiation chemistry, is discussed. The discussion is followed by a brief review of some of the simulation techniques, which have been recently applied to the problems of radiation chemistry: ion recombination in spurs and tracks of ionization, electron tunnelling in low-temperature glasses, electron localization in disordered media. (author)

  8. Small radiation field dosimetry with 2-methylalanine miniature dosimeters at K-band electron paramagnetic resonance

    International Nuclear Information System (INIS)

    Chen, F.; Guzman Calcina, C.S.; Almeida, A. de; Almeida, C.E. de; Baffa, O.

    2007-01-01

    Minidosimeters of 2-methyalanine (2MA) with millimeter dimensions were produced and tested for small radiation field dosimetry. Their performance was assessed by measuring the relative output factor (ROF), beam profile (BP) and penumbra width values and were determined for square fields of 0.5x0.5, 1x1, 3x3, 5x5 and 10x10cm 2 . These results were compared with those obtained for Kodak X-Omat V radiographic film. The 2MA minidosimeters (mini2MA) were irradiated with 6 MV X-rays Varian/Clinac 2100 linear accelerator with SSD of 100 cm and depth of 1.5 cm (depth for build-up equilibrium). EPR measurements were made with a K-Band (24 GHz) spectrometer. The ROF and BP results demonstrate that the dimensions of the mini2MA are adequate for the field sizes used in this experiment. The results for penumbra width indicate that the spatial resolution of the mini2MA is comparable with that of radiographic film

  9. Graphene-assisted near-field radiative heat transfer between corrugated polar materials

    International Nuclear Information System (INIS)

    Liu, X. L.; Zhang, Z. M.

    2014-01-01

    Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

  10. Radiation dose reduction without compromise to image quality by alterations of filtration and focal spot size in cerebral angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Joon; Park, Min Keun; Jung, Da Eun; Kang, Jung Han; Kim, Byung Moon [Dept. of Radiology, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2017-08-01

    Different angiographic protocols may influence the radiation dose and image quality. In this study, we aimed to investigate the effects of filtration and focal spot size on radiation dose and image quality for diagnostic cerebral angiography using an in-vitro model and in-vivo patient groups. Radiation dose and image quality were analyzed by varying the filtration and focal spot size on digital subtraction angiography exposure protocols (1, inherent filtration + large focus; 2, inherent + small; 3, copper + large; 4, copper + small). For the in-vitro analysis, a phantom was used for comparison of radiation dose. For the in-vivo analysis, bilateral paired injections, and patient cohort groups were compared for radiation dose and image quality. Image quality analysis was performed in terms of contrast, sharpness, noise, and overall quality. In the in-vitro analysis, the mean air kerma (AK) and dose area product (DAP)/frame were significantly lower with added copper filtration (protocols 3 and 4). In the in-vivo bilateral paired injections, AK and DAP/frame were significantly lower with filtration, without significant difference in image quality. The patient cohort groups with added filtration (protocols 3 and 4) showed significant reduction of total AK and DAP/patient without compromise to the image quality. Variations in focal spot size showed no significant differences in radiation dose and image quality. Addition of filtration for angiographic exposure studies can result in significant total radiation dose reduction without loss of image quality. Focal spot size does not influence radiation dose and image quality. The routine angiographic protocol should be judiciously investigated and implemented.

  11. Determination of dose rates in beta radiation fields using extrapolation chamber and GM counter

    International Nuclear Information System (INIS)

    Borg, J.; Christensen, P.

    1995-01-01

    The extrapolation chamber measurement method is the basic method for the determination of dose rates in beta radiation fields and the method has been used for the establishment of beta calibration fields. The paper describes important details of the method and presents results from the measurements of depth-dose profiles from different beta radiation fields with E max values down to 156 keV. Results are also presented from studies of GM counters for use as survey instruments for monitoring beta dose rates at the workplace. Advantages of GM counters are a simple measurement technique and high sensitivity. GM responses were measured from exposures in different beta radiation fields using different filters in front of the GM detector and the paper discusses the possibility of using the results from GM measurements with two different filters in an unknown beta radiation field to obtain a value of the dose rate. (Author)

  12. Quality assurance procedure for assessing mechanical accuracy of a radiation field center in stereotactic radiotherapy

    International Nuclear Information System (INIS)

    Tatsumi, Daisaku; Ienaga, Akinori; Nakada, Ryosei; Yomoda, Akane; Inoue, Makoto; Ichida, Takao; Hosono, Masako

    2012-01-01

    Stereotactic radiotherapy requires a quality assurance (QA) program that ensures the mechanical accuracy of a radiation field center. We have proposed a QA method for achieving the above requirement by conducting the Winston Lutz test using an electronic portal image device (EPID). An action limit was defined as three times the standard deviation. Then, the action limits for mean deviations of the radiation field center during collimator rotation, gantry rotation, and couch rotation in clockwise and counterclockwise resulted in 0.11 mm, 0.52 mm, 0.37 mm, and 0.41 mm respectively. Two years after the QA program was launched, the mean deviation of the radiation field center during gantry rotation exceeded the above action limit. Consequently, a mechanical adjustment for the gantry was performed, thereby restoring the accuracy of the radiation field center. A field center shift of 0.5 mm was also observed after a micro multi-leaf collimator was unmounted. (author)

  13. Magnetic resonance in medicine occupational exposure to static magnetic field and radiofrequency radiation

    International Nuclear Information System (INIS)

    Zivkovic, D.; Hrnjak, M.; Ivanovic, C.

    1997-01-01

    Medical personnel working with magnetic resonance imaging (MRI) devices could be exposed to static magnetic (M) field, time-varying M fields and radiofrequency (RF) radiation. The aim of work was to investigate the density of magnetic flux of static magnetic field and the power density of RF radiation which appear in the working environment around the 0.5 T MRI unit in one hospital. The density of magnetic flux of static magnetic field was measured with Hall Effect Gauss meter - Magnetech (Great Britain), and the power density of RF radiation was measured with broadband isotropic meter - The Narda Microwave Corp. (USA). The results of measurement show that the density of magnetic flux of static M field on working places are below threshold limit of exposure and the intensities of RF radiation are far below maximum permissible level. (author)

  14. Relative merits of size, field, and current on ignited tokamak performance

    International Nuclear Information System (INIS)

    Uckan, N.A.

    1988-01-01

    A simple global analysis is developed to examine the relative merits of size (L = a or R/sub 0 /), field (B/sub 0 /), and current (I) on ignition regimes of tokamaks under various confinement scaling laws. Scalings of key parameters with L, B/sub 0 /, and I are presented at several operating points, including (a) optimal path to ignition (saddle point), (b) ignition at minimum beta, (c) ignition at 10 keV, and (d) maximum performance at the limits of density and beta. Expressions for the saddle point and the minimum conditions needed for ohmic ignition are derived analytically for any confinement model of the form tau/sub E/ ∼ n/sup x/T/sup y/. For a wide range of confinement models, the ''figure of merit'' parameters and I are found to give a good indication of the relative performance of the devices where q* is the cylindrical safety factor. As an illustration, the results are applied to representative ''CIT'' (as a class of compact, high-field ignition tokamaks) and ''Super-JETs'' [a class of large-size (few x JET), low-field, high-current (≥20-MA) devices.

  15. Effect of weak magnetic field on the grain size of electrodeposited nickel

    International Nuclear Information System (INIS)

    Ansari, M.S.; Gul, N.

    2007-01-01

    Effect of weak magnetic field on the electro-deposition of nickel onto copper electrode has been investigated. The working conditions were optimized through adjustment of cathodic current density (CCD), deposition time, bath temperature and pH of the medium. For electro-deposition in the absence of magnetic field, the optimum conditions comprised of pH = 4.0+- 0.5, average CCD = 22.5 +- 0.5 mA cm/sup -2/ and bath temperature in the range from 25 to 30 degree C. The same conditions were maintained for the electrodeposition while applying magnetic field of 0.75 kG. The morphological features of the Ni-deposits on copper cathode were compared for the two cases. The applied magnetic field not only enhanced the amount of nickel deposition but also improved the quality of the deposit. Surface morphology of the electro-deposited nickel has been monitored using scanning electron microscopy (SEM); the preliminary investigation has shown that the grain size decreased with the applied magnetic field case. One possible explanation to this behavior is the convection flow of cations close to the electrode surface induced by the Lorentz force which also influences the ion-migration. (author)

  16. Utilization technique of 'radiation management manual in medical field (2012).' What should be learnt from the Fukushima nuclear accident

    International Nuclear Information System (INIS)

    Kikuchi, Toru

    2014-01-01

    From the abstract of contents of the 'Radiation management manual in medical field (2012),' the utilization technique of the manual is introduced. Introduced items are as follows: (1) Exposure management; exposure management for radiation medical workers, patients, and citizens in the medical field, and exposure management for radiation workers and citizens involved in the emergency work related to the Fukushima nuclear accident, (2) Health management; health management for radiation medical workers, (3) Radiation education: Education/training for radiation medical workers, and radiation education for health care workers, (4) Accident and emergency measures; emergency actions involved in the radiation accidents and radiation medicine at medical facilities

  17. PWR radiation fields at combustion engineering plants through mid-1985: Final report

    International Nuclear Information System (INIS)

    Barshay, S.S.; Beineke, T.A.; Bradshaw, R.W.

    1987-01-01

    This report presents the results of the initial phase of the EPRI-PWR Standard Radiation Monitoring Program (SRMP) for PWR nuclear power plants with Nuclear Steam Supply Systems supplied by Combustion Engineering, Inc. The purposes of the SRMP are to provide reliable, consistent and systematic measurements of the rate of radiation-field buildup at operating PWR's; and to use that information to identify opportunities for radiation control and the consequent reduction of occupational radiation exposure. The report includes radiation surveys from seven participating power plants. These surveys were conducted at well-defined locations on the reactor coolant loop piping and steam generators, and/or inside the steam generator channel heads. In most cases only one survey is available from each power plant, so that conclusions about the rate of radiation-field buildup are not possible. Some observations are made about the distribution pattern of radiation levels within the steam generator channel heads and around the reactor coolant loops. The report discusses the relationship between out-of-core radiation fields (as measured by the SRMP) and: the pH of the reactor coolant, the concentration of lithium hydroxide in the reactor coolant, and the frequency of changes in reactor power level. In order to provide data for possible future correlations of these parameters with the SRMP radiation-field data, the report summarizes information available from participating plants on primary coolant pH, and on the frequency of changes in reactor power level. 12 refs., 22 figs., 7 tabs

  18. Determination of dose rates in beta radiation fields using extrapolation chamber and GM counter

    DEFF Research Database (Denmark)

    Borg, J.; Christensen, P.

    1995-01-01

    of depth-dose profiles from different beta radiation fields with E(max) values down to 156 keV. Results are also presented from studies of GM counters for use as survey instruments for monitoring beta dose rates at the workplace. Advantages of GM counters are a simple measurement technique and high...... sensitivity. GM responses were measured from exposures in different beta radiation fields using different filters in front of the GM detector and the paper discusses the possibility of using the results from GM measurements with two different filters in an unknown beta radiation field to obtain a value...

  19. Measurement and analysis of the electric field radiation in pulsed power system of linear induction accelerator

    International Nuclear Information System (INIS)

    Cheng Qifeng; Ni Jianping; Meng Cui; Cheng Cheng; Liu Yinong; Li Jin

    2009-01-01

    The close of high voltage switch in pulsed power system of linear induction accelerator often radiates strong transient electric field, which may influence ambient sensitive electric equipment, signals and performance of other instruments, etc. By performing gridded measurement around the Marx generator, the general distribution law and basic characters of electric field radiation are summarized. The current signal of the discharge circuit is also measured, which demonstrates that the current and the radiated electric field both have a resonance frequency about 150 kHz, and contain much higher frequency components. (authors)

  20. The exact electromagnetic field description of photon emission, absorption, and radiation pattern. II.

    Science.gov (United States)

    Grimes, Dale M; Grimes, Craig A

    2002-10-01

    This is the second of two articles, the first of which contains a proposed explanation of quantum theory based upon electron nonlocality and classical electrodynamics. In this second article classical field theory is used to describe a unique field set for exchange of radiation between an atomic eigenstate and the far field. The radiation satisfies the thermodynamic condition of reversibility as described by Boltzmann, Planck, and Einstein. The exchanged radiation supports the kinematic properties of photons, and it can be emitted or absorbed by a vanishingly small volume.

  1. FGF signaling regulates the number of posterior taste papillae by controlling progenitor field size.

    Directory of Open Access Journals (Sweden)

    Camille I Petersen

    2011-06-01

    Full Text Available The sense of taste is fundamental to our ability to ingest nutritious substances and to detect and avoid potentially toxic ones. Sensory taste buds are housed in papillae that develop from epithelial placodes. Three distinct types of gustatory papillae reside on the rodent tongue: small fungiform papillae are found in the anterior tongue, whereas the posterior tongue contains the larger foliate papillae and a single midline circumvallate papilla (CVP. Despite the great variation in the number of CVPs in mammals, its importance in taste function, and its status as the largest of the taste papillae, very little is known about the development of this structure. Here, we report that a balance between Sprouty (Spry genes and Fgf10, which respectively antagonize and activate receptor tyrosine kinase (RTK signaling, regulates the number of CVPs. Deletion of Spry2 alone resulted in duplication of the CVP as a result of an increase in the size of the placode progenitor field, and Spry1(-/-;Spry2(-/- embryos had multiple CVPs, demonstrating the redundancy of Sprouty genes in regulating the progenitor field size. By contrast, deletion of Fgf10 led to absence of the CVP, identifying FGF10 as the first inductive, mesenchyme-derived factor for taste papillae. Our results provide the first demonstration of the role of epithelial-mesenchymal FGF signaling in taste papilla development, indicate that regulation of the progenitor field size by FGF signaling is a critical determinant of papilla number, and suggest that the great variation in CVP number among mammalian species may be linked to levels of signaling by the FGF pathway.

  2. Power Scaling of Petroleum Field Sizes and Movie Box Office Earnings.

    Science.gov (United States)

    Haley, J. A.; Barton, C. C.

    2017-12-01

    The size-cumulative frequency distribution of petroleum fields has long been shown to be power scaling, Mandelbrot, 1963, and Barton and Scholz, 1995. The scaling exponents for petroleum field volumes range from 0.8 to 1.08 worldwide and are used to assess the size and number of undiscovered fields. The size-cumulative frequency distribution of movie box office earnings also exhibits a power scaling distribution for domestic, overseas, and worldwide gross box office earnings for the top 668 earning movies released between 1939 and 2016 (http://www.boxofficemojo.com/alltime/). Box office earnings were reported in the dollars-of-the-day and were converted to 2015 U.S. dollars using the U.S. consumer price index (CPI) for domestic and overseas earnings. Because overseas earnings are not reported by country and there is no single inflation index appropriate for all overseas countries. Adjusting the box office earnings using the CPI index has two effects on the power functions fit. The first is that the scaling exponent has a narrow range (2.3 - 2.5) between the three data sets; and second, the scatter of the data points fit by the power function is reduced. The scaling exponents for the adjusted value are; 2.3 for domestic box office earnings, 2.5 for overseas box office earnings, and 2.5 worldwide box office earnings. The smaller the scaling exponent the greater the proportion of all earnings is contributed by a smaller proportion of all the movies: where E = P (a-2)/(a-1) where E is the percentage of earnings, P is the percentage of all movies in the data set. The scaling exponents for box office earnings (2.3 - 2.5) means that approximately 20% of the top earning movies contribute 70-55% of all the earnings for domestic, worldwide earnings respectively.

  3. SIZE AND FIELD OF ACTIVITY INFLUENCE ON WEB SITES FUNCTIONALITY FOR ROMANIAN COMPANIES

    Directory of Open Access Journals (Sweden)

    Tarca Ioan

    2008-05-01

    Full Text Available The internet became an important part of the company’s informational system. In order to take advantage on the Internet’s interactive nature, a lot of companies have created their own websites. Companies use the website for numerous applications: to promote themselves, online shopping, and communication with targeted clients. This study reveals the fact that the company’s size and field of activity have influence on website’s functionality and interactivity. Small companies use the website to successfully compete corporations which do not have yet necessary stimulants to fully exploit the internet capacities.

  4. Development of superconducting poloidal field coils for medium and large size tokamaks

    International Nuclear Information System (INIS)

    Dittrich, H.-G.; Forster, S.; Hofmann, A.

    1983-01-01

    Large long pulse tokamak fusion experiments require the use of superconducting poloidal field (PF) coils. In the past not much attention has been paid to the development of such coils. Therefore a development programme has been initiated recently at KfK. In this report start with summarizing the relevant PF coil parameters of some medium and large size tokamaks presently under construction or design, respectively. The most important areas of research and development work are deduced from these parameters. Design considerations and first experimental results concerning low loss conductors, cooling concepts and structural components are given

  5. Isolation of radiation resistant fungal strains from highly radioactive field

    International Nuclear Information System (INIS)

    Adam, Y.M.; Aziz, N.H.; Attaby, H.S.H.

    1995-01-01

    This study examined the radiation resistance of fungal flora isolated from the hot-lab around the radiation sources, cobalt 137 and radium 226 . The predominant mould species were: Aspergillus flavus, A. Niger, penicillium chrysogenum, cladosporium herbarum, fusarium oxysporum and alternaria citri. The D 10 values of F. Oxysporum; 2.00 KGy, A. Flavus; 1.40 KGy, P. chrysogenum; 1.15 KGy, and A. citri; 0.95 KGy, are about 1.67, 3.10, 1.92 and 1.36 folds as the D 1 0 values of the same isolates recovered from soil

  6. Origin of temperature and field dependence of magnetic skyrmion size in ultrathin nanodots

    Science.gov (United States)

    Tomasello, R.; Guslienko, K. Y.; Ricci, M.; Giordano, A.; Barker, J.; Carpentieri, M.; Chubykalo-Fesenko, O.; Finocchio, G.

    2018-02-01

    Understanding the physical properties of magnetic skyrmions is important for fundamental research with the aim to develop new spintronic device paradigms where both logic and memory can be integrated at the same level. Here, we show a universal model based on the micromagnetic formalism that can be used to study skyrmion stability as a function of magnetic field and temperature. We consider ultrathin, circular ferromagnetic magnetic dots. Our results show that magnetic skyrmions with a small radius—compared to the dot radius—are always metastable, while large radius skyrmions form a stable ground state. The change of energy profile determines the weak (strong) size dependence of the metastable (stable) skyrmion as a function of temperature and/or field.

  7. Modelling radiation fields of ion beams in tissue-like materials

    International Nuclear Information System (INIS)

    Burigo, Lucas Norberto

    2014-01-01

    Fast nuclei are ionizing radiation which can cause deleterious effects to irradiated cells. The modelling of the interactions of such ions with matter and the related effects are very important to physics, radiobiology, medicine and space science and technology. A powerful method to study the interactions of ionizing radiation with biological systems was developed in the field of microdosimetry. Microdosimetry spectra characterize the energy deposition to objects of cellular size, i.e., a few micrometers. In the present thesis the interaction of ions with tissue-like media was investigated using the Monte Carlo model for Heavy-Ion Therapy (MCHIT) developed at the Frankfurt Institute for Advanced Studies. MCHIT is a Geant4-based application intended to benchmark the physical models of Geant4 and investigate the physical properties of therapeutic ion beams. We have implemented new features in MCHIT in order to calculate microdosimetric quantities characterizing the radiation fields of accelerated nucleons and nuclei. The results of our Monte Carlo simulations were compared with recent experimental microdosimetry data. In addition to microdosimetry calculations with MCHIT, we also investigated the biological properties of ion beams, e.g. their relative biological effectiveness (RBE), by means of the modified Microdosimetric-Kinetic model (MKM). The MKM uses microdosimetry spectra in describing cell response to radiation. MCHIT+MKM allowed us to study the physical and biological properties of ion beams. The main results of the thesis are as follows: MCHIT is able to describe the spatial distribution of the physical dose in tissue-like media and microdosimetry spectra for ions with energies relevant to space research and ion-beam cancer therapy; MCHIT+MKM predicts a reduction of the biological effectiveness of ions propagating in extended medium due to nuclear fragmentation reactions; We predicted favourable biological dose-depth profiles for monoenergetic helium and

  8. Television system for verification and documentation of treatment fields during intraoperative radiation therapy

    International Nuclear Information System (INIS)

    Fraass, B.A.; Harrington, F.S.; Kinsella, T.J.; Sindelar, W.F.

    1983-01-01

    Intraoperative radiation therapy (IORT) involves direct treatment of tumors or tumor beds with large single doses of radiation. The verification of the area to be treated before irradiation and the documentation of the treated area are critical for IORT, just as for other types of radiation therapy. A television system which allows the target area to be directly imaged immediately before irradiation has been developed. Verification and documentation of treatment fields has made the IORT television system indispensable

  9. Actual conditions of radiation control in radioisotope utilization field

    International Nuclear Information System (INIS)

    Kakihara, Koji

    1980-01-01

    It may be said that the actual conditions on radiation safety are being improved in utilizing radioisotopes or radiation in Japan. It depends greatly on the results of the voluntary effort of users and the regulations by the ''radiation injury prevention law'' and its relevant ordinances. However, the actual conditions of the strict observation of the law are much insufficient. According to the results of official inspection in 1978, 60% of whole enterprises concerned and 73% of educational and medical organizations were judged as incomplete. Such tendency should not be left as it is, but it should also be noticed that there are realities that critical accidents or injuries have not occurred even in such conditions as many violations mentioned above. Since the existing law has not been subjected to essential revision in the past two decades, it might be said that the law does not properly fit to the present conditions because the progress of related techniques was made during this period. Meanwhile, difficulties exist in measuring the low level concentration in the use of low energy radioisotopes or tracer experiments such as in the process analysis in factories or in the analysis of the movement of trace constituent in soil. Further, there is a problem on the necessity of securing the chief technicians handling radiation, and there is the contradiction that the chief technicians are useless in normal condition but are powerless in case of accidents. This situation should be improved as soon as possible. (Wakatsuki, Y.)

  10. Radiation protection measurement - spectral solutions in special fields

    International Nuclear Information System (INIS)

    Urban, F.J.; Trliber, K.H.; Schwerdn, K.; Laube, S.

    1997-01-01

    The exposition to ionizing radiation is a fact for nearly every person. One part of the exposition is due to natural or man made radioisotopes occurring in the environment. Another part exists because of technical sources. mainly x-ray machines for medical diagnostics. (authors)

  11. Dose loading mathematical modelling of moving through heterogeneous radiation fields

    International Nuclear Information System (INIS)

    Batyij, Je.V.; Kotlyarov, V.T.

    2006-01-01

    Software component for management of data on gamma exposition dose spatial distribution was created in the frameworks of the Ukryttya information model creation. Availability of state-of-the-art programming technologies (NET., ObjectARX) for integration of different models of radiation-hazardous condition to digital engineer documentation system (AutoCAD) was shown on the basis of the component example

  12. Effects of ultraviolet radiation on rates and size distribution of primary production by Lake Erie phytoplankton

    International Nuclear Information System (INIS)

    Hiriart, V.P.; Greenberg, B.M.; Guildford, S.J.; Smith, R.E.H.

    2002-01-01

    The impact of natural solar ultraviolet radiation (UVR), particularly UVB (297-320 nm), on phytoplankton primary production in Lake Erie was investigated during the spring and summer of 1997. Radiocarbon incorporation and size-selective filtration was used to trace total production and its distribution among particulate and dissolved pools. On average, 1-h exposures produced half the UVB-dependent inhibition of total production realized in 8-h exposures, indicating rapid kinetics of photoinhibition. Cumulative UVB-dependent photoinhibition averaged 36% in 8-h simulated surface exposures. The efficiency of photoinhibition was greater for N-deficient than N-replete communities, but was not related to phytoplankton light history, P limitation, or the dominant genera. The proportion of recently fixed carbon occurring in the dissolved pool after 8-h exposures was significantly greater in higher-UVB treatments, whereas the share in picoplankton (<2 μm) was significantly lower. Significant UVB-dependent inhibition of total production was limited on average to relatively severe exposures, but the rapid kinetics of inhibition and the apparent effects on the allocation of carbon suggest it may be important to the lake's food web. Differences in optical properties and thermal stratification patterns suggested that the relatively turbid west basin was potentially more susceptible to UVR photoinhibition than the more transparent east or central basins. (author)

  13. Impact of radiation therapy fraction size on local control of early glottic carcinoma

    International Nuclear Information System (INIS)

    Yu, Edward; Shenouda, George; Beaudet, Marie P.; Black, Martin J.

    1997-01-01

    Purpose: Different radiotherapy fractionation schedules were used over a 10-year period to treat patients with early squamous cell carcinoma of the vocal cords at McGill University. A retrospective analysis was performed to study the effect of fraction size on local control in this group of patients. Methods and Materials: A total of 126 previously untreated patients with T1 invasive squamous cell carcinoma of the true vocal cords were irradiated between January 1978 and December 1988 in the Department of Radiation Oncology at McGill University. All patients received megavoltage irradiation, 94 patients received daily fractions > 2 Gy (64 patients received 50 Gy with once-daily 2.5-Gy fractions, and 30 received 65.25 Gy in 29 fractions of 2.25 Gy each), and 32 patients were treated to a dose of 66 Gy in 33 fractions with 2 Gy/fraction. Patients' characteristics of prognostic importance were equally distributed between the two fractionation groups. Results: At a median follow-up of 84 months, the 10-year disease-free survival and overall survival were 76% and 93%, respectively. Local control for patients treated with > 2 Gy fraction was 84%, compared to 65.6% for those treated with 2-Gy fractions (p = 0.026). Among the prognostic factors tested, such as gender, age, stage, anterior and posterior commissure involvement, smoking history, and fraction size, the latter was the only significant predictor of local control for the whole group of patients in univariate (p = 0.041) and multivariate (p = 0.023) analysis. There was no observed difference in the incidence of complications between the two fraction groups. Conclusions: From the results of this retrospective review of patients treated with radiotherapy for T1 true vocal cord cancer, and within the range of total doses and overall treatment times used in our patients, it was found that fractionation schedules using daily fraction size > 2 Gy are associated with a better local control than schedules delivering 2 Gy

  14. Becquerel century: good and bad in radiation field

    International Nuclear Information System (INIS)

    Sandru, P.

    1996-01-01

    The purpose of this poster is to offer a synthetic as well as comprehensive image on this century of radioactivity with its beneficial and non-beneficial aspects. It is both a historical and an allegorical graphical presentation of the man's habitat, which have had in all the times a strong radioactive component. In order to paraphrase, but in a different way, another optimist message of this century perhaps we have to say that the cradle of man is radioactive and all the steps outside it should be very carefully considered. During this last century man started to challenge the nature in its intimate features, i.e. those associated to radioactivity phenomenon. In the first phase the world was fully confident on the radiation peaceful applications, then in the second phase all these beneficial aspects have been detonated toward military applications which astonished all the people by the harmful effects of radiation, finally we have been passing a new era dominated, all over the world by a spirit of harmonization and consent by which we are going to reach a globalization of radiation protection and safety principles and measures. Even if it is the latest source of energy which man has stolen from the nature, nuclear energy is now - from a technical point of view - a strong option for the human future and is going to gain more and more in the public acceptance branch. If this poster should have been confined in a phrase then the motto can be: with too much radiation we cannot be and live, but without radiation we cannot survive. (author)

  15. Three-dimensional inhomogeneous rain fields: implications for the distribution of intensity and polarization of the microwave thermal radiation.

    Science.gov (United States)

    Ilyushin, Yaroslaw; Kutuza, Boris

    Observations and mapping of the upwelling thermal radiation of the Earth is the very promising remote sensing technique for the global monitoring of the weather and precipitations. For reliable interpretation of the observation data, numerical model of the microwave radiative transfer in the precipitating atmosphere is necessary. In the present work, numerical simulations of thermal microwave radiation in the rain have been performed at three wavelengths (3, 8 and 22 mm). Radiative properties of the rain have been simulated using public accessible T-matrix codes (Mishchenko, Moroz) for non-spherical particles of fixed orientation and realistic raindrop size distributions (Marshall-Palmer) within the range of rain intensity 1-100 mm/h. Thermal radiation of infinite flat slab medium and isolated rain cell of kilometer size has been simulated with finite difference scheme for the vectorial radiative transfer equation (VRTE) in dichroic scattering medium. Principal role of cell structure of the rain field in the formation of angular and spatial distribution of the intensity and polarization of the upwelling thermal radiation has been established. Possible approaches to interpretation of satellite data are also discussed. It is necessary that spatial resolution of microwave radiometers be less than rain cell size. At the present time the resolution is approximately 15 km. It can be considerably improved, for example by two-dimensional synthetic aperture millimeter-wave radiometric interferometer for measuring full-component Stokes vector of emission from hydrometeors. The estimates show that in millimeter band it is possible to develop such equipment with spatial resolution of the order of 1-2 km, which is significantly less than the size of rain cell, with sensitivity 0.3-0.5 K. Under this condition the second Stokes parameter may by successfully measured and may be used for investigation of precipitation regions. Y-shaped phased array antenna is the most promising to

  16. A solution algorithm for calculating photon radiation fields with the aid of the Monte Carlo method

    International Nuclear Information System (INIS)

    Zappe, D.

    1978-04-01

    The MCTEST program and its subroutines for the solution of the Boltzmann transport equation is presented. The program renders possible to calculate photon radiation fields of point or plane gamma sources. After changing two subroutines the calculation can also be carried out for the case of directed incidence of radiation on plane shields of iron or concrete. (author)

  17. Complex workplace radiation fields at European high-energy accelerators and thermonuclear fusion facilities

    CERN Document Server

    Bilski, P; D'Errico, F; Esposito, A; Fehrenbacher, G; Fernàndez, F; Fuchs, A; Golnik, N; Lacoste, V; Leuschner, A; Sandri, S; Silari, M; Spurny, F; Wiegel, B; Wright, P

    2006-01-01

    This report outlines the research needs and research activities within Europe to develop new and improved methods and techniques for the characterization of complex radiation fields at workplaces around high-energy accelerators and the next generation of thermonuclear fusion facilities under the auspices of the COordinated Network for RAdiation Dosimetry (CONRAD) project funded by the European Commission.

  18. Dependence of radiation electric conductivity on intensity of external electric field in polymeric dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Sichkar, V P; Tyutnev, A P; Vaisberg, S E [Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR)

    1975-10-01

    The radiational conductivity (Gsub(p)) at different electric field potentials (E) for a number of low- and high-density polymers was investigated. In a number of cases temperature variations were introduced. Measurements were carried out also under conditions of a single impulse of high-power radiation dose. A relationship was obtained between Gsub(p) and E.

  19. Experimental study of the counting loss in an ionization chamber in pulsed radiation fields

    International Nuclear Information System (INIS)

    Goncalez, O.L.; Yanagihara, L.S.; Veissid, V.L.C.P.; Herdade, S.B.; Teixeira, A.N.

    1983-01-01

    The behavior of an ionization chamber gamma ray monitor in a pulsed radiation field at a linear electron accelerator facility was studied experiementally. A loss of sensitivity was observed as expected due to the pulsed nature of the radiation. By fitting the experiemental data to semi-empirical expressions, parameters for the correction of the counting efficiency were obtained. (Author) [pt

  20. Radiation protection medicine - a special field of health care and industrial safety

    International Nuclear Information System (INIS)

    Arndt, D.

    1988-01-01

    The definition of the term radiation protection medicine is followed by a brief account of the pathophysiology of radiation effects. Developments in the special field of general and occupational health are also described together with relevant GDR regulations. Information is provided on what is done at present at various levels in the GDR, in the context of peaceful use of nuclear energy, to provide adequate services in radiation protection medicine for all radiation workers and the population, with reference to the scope of activities of the Institute of Medicine attached to the National Board for Atomic Safety and Radiation Protection, the network of works medical officers in charge of radiation protection and the system for clinical treatment of acute radiation damage. (author)

  1. The effects of emitter-tied field plates on lateral PNP ionizing radiation response

    International Nuclear Information System (INIS)

    Barnaby, H.J.; Schrimpf, R.D.; Cirba, C.R.; Pease, R.L.; Fleetwood, D.M.; Kosier, S.L.

    1998-03-01

    Radiation response comparisons of lateral PNP bipolar technologies reveal that device hardening may be achieved by extending the emitter contact over the active base. The emitter-tied field plate suppresses recombination of carriers with interface traps

  2. A radiation-electric-field combination principle for SO2-oxidation in Ar-mixtures

    International Nuclear Information System (INIS)

    Leonhardt, J.; Krueger, H.; Popp, P.; Boes, J.

    1981-01-01

    A simple model for a radiation-induced SO 2 -oxidation in Ar using SO 2 /O 2 /Ar-mixtures has been described by Leonhardt a.o. It is possible to improve the efficiency of the radiation-induced SO 2 -oxidation in such mixtures if the electrons produced by the ionizing radiation are accelerated by means of an electric field. The energy of the field-accelerated electrons must be high enough to form reactive SO 2 radicals but not high enough to ionize the gas mixture. Such an arrangement is described. The connection between the rate of SO 3 -formation and the electric field and the connection between SO 3 -formation and decreasing of the O 2 -concentration in the reaction chaimber were experimentally determined. Further the G-values attained by means of the radiation-electric-field combination are discussed. (author)

  3. Attenuation of VHE Gamma Rays by the Milky Way Interstellar Radiation Field

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, Igor V.; /Stanford U., HEPL; Porter, Troy A.; /Louisiana State U.; Strong, Andrew W.; /Garching, Max Planck Inst., MPE

    2006-04-19

    The attenuation of very high energy gamma rays by pair production on the Galactic interstellar radiation field has long been thought of as negligible. However, a new calculation of the interstellar radiation field consistent with multi-wavelength observations by DIRBE and FIRAS indicates that the energy density of the Galactic interstellar radiation field is higher, particularly in the Galactic center, than previously thought. We have made a calculation of the attenuation of very high energy gamma rays in the Galaxy using this new interstellar radiation field which takes into account its nonuniform spatial and angular distributions. We find that the maximum attenuation occurs around 100 TeV at the level of about 25% for sources located at the Galactic center, and is important for both Galactic and extragalactic sources.

  4. The role of packaging size on contamination rates during simulated presentation to a sterile field.

    Directory of Open Access Journals (Sweden)

    Tony Trier

    Full Text Available The objective of this study was to assess the impact of package size on the contact between medical devices and non-sterile surfaces (i.e. the hands of the practitioner and the outside of the package during aseptic presentation to a simulated sterile field. Rationale for this objective stems from the decades-long problem of hospital-acquired infections. This work approaches the problem from a unique perspective, namely packaging size.Randomized complete block design with subsampling.Research study conducted at professional conferences for surgical technologists and nursing professionals.Ninety-seven healthcare providers, primarily surgical technologists and nurses.Participants were gloved and asked to present the contents of six pouches of three different sizes to a simulated sterile field. The exterior of pouches and gloves of participants were coated with a simulated contaminant prior to each opening trial. After presentation to the simulated sterile field, the presence of the contaminant on package contents was recorded as indicative of contact with non-sterile surfaces and analyzed in a binary fashion using a generalized linear mixed model.Recruited subjects were 26-64 years of age (81 females, 16 males, with 2.5-44 years of professional experience. Results indicated a significant main effect of pouch size on contact rate of package contents (P = 0.0108, whereby larger pouches induced greater rates of contact than smaller pouches (estimates±SEM: 14.7±2.9% vs. 6.0±1.7%, respectively.This study utilized novel methodologies which simulate contamination in aseptic presentation. Results of this work indicate that increased contamination rates are associated with larger pouches when compared to smaller pouches. The results add to a growing body of research which investigate packaging's role in serving as a pathway for product contamination during aseptic presentation. Future work should investigate other packaging design factors (e

  5. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives.

    Science.gov (United States)

    Contado, Catia; Ravani, Laura; Passarella, Martina

    2013-07-25

    Four types of SiO2, available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w(-1)) a nearly silica-free instant barley coffee powder with a known SiO2 sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO2 particles and verify the new particle size distribution. The SiO2 content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w(-1)). The protocol to isolate the silica particles was so applied to the most SiO2-rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Use of mobile robots for mapping radiation field around particle accelerators

    International Nuclear Information System (INIS)

    Sharma, S.; Agashe, V.; Pal, P.K.

    2011-01-01

    In Particle Accelerators, when the accelerated particles hit the target or inadvertently strike the wall, prompt and induced radiation is produced. It is necessary to monitor the resulting radiation field in order to reduce radiation exposure to operating personnel, as well as to locate points of leakage of the particle beam. This paper describes the development of mobile robots equipped with onboard radiation detectors for mapping such radiation fields. They include a user interface software running on a host computer to tele operate the robot, monitor radiation levels, and build and display a radiation map out of these data through interpolation. One such robot (ARMER-II), designed and developed by us in consultation with Radiation Safety Division (RSD), is a portable mobile robot for identifying locations with radiation levels higher than permissible limits. Its remote interface computes and guides the robot to move in a direction in which the increase in intensity of radiation is the steepest. Another mobile robot (ARMER-I) has a telescopic arm fitted with a light and small GM tube. This also can be controlled remotely, and is very useful in remote measurement of radiation from locations which are difficult to reach otherwise. Another version (ASHWA) has been successfully adapted by VECC, Kolkata, for gamma and neutron radiation profiling in the cyclotron vault area. We are presently working on the design and development of a four-wheel differentially driven mobile robot (RADMAPPER) with higher payload capacity for carrying radiation detectors like gamma camera and neutron dosimeters and positioning them at desired heights. With appropriate localization capability, this is going to be a very flexible mobile robot based system for radiation profiling around particle accelerators. The specification for this robot has been prepared in consultation with VECC for use in their cyclotron facilities. (author)

  7. Design and testing of indigenous cost effective three dimensional radiation field analyser (3D RFA).

    Science.gov (United States)

    Ganesh, K M; Pichandi, A; Nehru, R M; Ravikumar, M

    2014-06-01

    The aim of the study is to design and validate an indigenous three dimensional Radiation Field Analyser (3D RFA). The feed system made for X, Y and Z axis movements is of lead screw with deep ball bearing mechanism made up of stain less steel driven by stepper motors with accuracy less than 0.5 mm. The telescopic column lifting unit was designed using linear actuation technology for lifting the water phantom. The acrylic phantom with dimensions of 800 x 750 x 570 mm was made with thickness of 15 mm. The software was developed in visual basic programming language, classified into two types, viz. beam analyzer software and beam acquisition software. The premeasurement checks were performed as per TG 106 recommendations. The physical parameters of photon PDDs such as Dmax, D10, D20 and Quality Index (QI), and the electron PDDs such as R50, Rp, E0, Epo and X-ray contamination values can be obtained instantaneously by using the developed RFA system. Also the results for profile data such as field size, central axis deviation, penumbra, flatness and symmetry calculated according to various protocols can be obtained for both photon and electron beams. The result of PDDs for photon beams were compared with BJR25 supplement values and the profile data were compared with TG 40 recommendation. The results were in agreement with standard protocols.

  8. Nuclear energy - Reference beta-particle radiation - Part 2: Calibration fundamentals related to basic quantities characterizing the radiation field

    International Nuclear Information System (INIS)

    2004-01-01

    ISO 6980 consists of the following parts, under the general title Nuclear energy - Reference beta-particle radiation: Part 1: Method of production; Part 2: Calibration fundamentals related to basic quantities characterizing the radiation field; Part 3: Calibration of area and personal dosimeters and determination of their response as a function of energy and angle of incidence. This part 2 of ISO 6980 specifies methods for the measurement of the directional absorbed-dose rate in a tissue-equivalent slab phantom in the ISO 6980 reference beta-particle radiation fields. The energy range of the beta-particle-emitting isotopes covered by these reference radiations is 0.066 to 3.54 MeV (maximum energy). Radiation energies outside this range are beyond the scope of this standard. While measurements in a reference geometry (depth of 0.07 mm at perpendicular incidence in a tissue-equivalent slab phantom) with a reference class extrapolation chamber are dealt with in detail, the use of other measurement systems and measurements in other geometries are also described, although in less detail. The ambient dose equivalent, H*(10) as used for area monitoring of strongly penetrating radiation, is not an appropriate quantity for any beta radiation, even for that penetrating a 10 mm thick layer of ICRU tissue (i.e. E max > 2 MeV). If adequate protection is provided at 0.07 mm, only rarely will one be concerned with other depths, for example 3 mm. This document is geared towards organizations wishing to establish reference-class dosimetry capabilities for beta particles, and serves as a guide to the performance of dosimetry with the reference class extrapolation chamber for beta-particle dosimetry in other fields. Guidance is also provided on the statement of measurement uncertainties

  9. A simple ionizing radiation spectrometer/dosimeter based on radiation sensing field effect transistors (RadFETs)

    International Nuclear Information System (INIS)

    Moreno, D.J.; Hughes, R.C.; Jenkins, M.W.; Drumm, C.R.

    1997-01-01

    This paper reports on the processing steps in a silicon foundry leading to improved performance of the Radiation Sensing Field Effect Transistor (RadFET) and the use of multiple RadFETs in a handheld, battery operated, combination spectrometer/dosimeter

  10. On-axis and far-field sound radiation from resilient flat and dome-shaped radiators

    NARCIS (Netherlands)

    Aarts, R.M.; Janssen, A.J.E.M.

    2009-01-01

    On-axis and far-field series expansions are developed for the sound pressure due to an arbitrary, circular symmetric velocity distribution on a flat radiator in an infinite baffle. These expansions are obtained by expanding the velocity distributions in terms of orthogonal polynomials

  11. Mapping the radiation fields at a research reactor

    International Nuclear Information System (INIS)

    Soegaard-Hansen, Jens; Warming, Lisbeth

    1999-01-01

    The DR 3 reactor at Risoe National Laboratory is a multipurpose research reactor. It has the status of a Large European Beam facility therefor its neutron scattering spectrometers are used by many visiting scientists. As a supplement to the routine health physics monitoring programmes a special survey has been made to get more detailed information of the radiation levels in the hall and of the most important sources of the radiation. The special survey consisted of three sorts of measurements: an extra set of thermoluminescence dosimeters, a set of continuous measurements of the dose rate at selected places and spot measurements with handheld instruments around the spectrometers. Some of the results from the survey are presented. (au)

  12. Improvements relating to the restriction of fields of radiation

    International Nuclear Information System (INIS)

    Flocee, R.

    1977-01-01

    A method is described for delimiting the irradiation target area in radiotherapeutic treatments. The method is based on the realisation that it is possible to modify the effective cross section of a beam of radiation by means of a device which can be regarded as a secondary diaphragm, with an aperture framed by the heavy metal powder composition, which has radiation absorption properties. The heavy metal may be W or Pb, the grains of which are held together by the binding agent. The binding agent, being of the type known as a 'pressure-sensitive adhesive'. The method has the advantage that there is no need to employ either the therapeutic unit or an expensive simulator for construction of the beam cross section modifying device, nor has the patient to be present when this step is performed. Also the device employed is reusable. An example of the manufacture of the composition is described. Notes are also included on treatment techniques. (U.K.)

  13. Near-field radiative heat transfer between metasurfaces

    DEFF Research Database (Denmark)

    Dai, Jin; Dyakov, Sergey A.; Bozhevolnyi, Sergey I.

    2016-01-01

    Metamaterials possess artificial bulk and surface electromagnetic states. Tamed dispersion properties of surface waves allow one to achieve a controllable super-Planckian radiative heat transfer (RHT) process between two closely spaced objects. We numerically demonstrate enhanced RHT between two...... and highly geometrically tailorable. Our simulation also reveals thermally excited nonresonant surface waves in constituent metallic materials may play a prevailing role for RHT at an extremely small separation between two metal plates, rendering metamaterial modes insignificant for the energy-transfer...

  14. Effects of external radiation fields on line emission—application to star-forming regions

    Energy Technology Data Exchange (ETDEWEB)

    Chatzikos, Marios; Ferland, G. J. [University of Kentucky, Lexington, KY 40506 (United States); Williams, R. J. R. [AWE plc, Aldermaston, Reading RG7 4PR (United Kingdom); Porter, Ryan [Department of Physics and Astronomy and Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451 (United States); Van Hoof, P. A. M., E-mail: mchatzikos@gmail.com [Royal Observatory of Belgium, Avenue Circulaire 3, B-1180 Uccle (Belgium)

    2013-12-20

    A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background, as well as by a nearby active galactic nucleus. These radiation fields excite atoms and molecules and produce emission in different ways. We revisit the escape probability theorem and derive a novel expression that accounts for the presence of external radiation fields. We show that when the field is isotropic the escape probability is reduced relative to that in the absence of external radiation. This is in agreement with previous results obtained under ad hoc assumptions or with the two-level system, but can be applied to complex many-level models of atoms or molecules. This treatment is in the development version of the spectral synthesis code CLOUDY. We examine the spectrum of a Spitzer cloud embedded in the local interstellar radiation field and show that about 60% of its emission lines are sensitive to background subtraction. We argue that this geometric approach could provide an additional tool toward understanding the complex radiation fields of starburst galaxies.

  15. ANOLE Portable Radiation Detection System Field Test and Evaluation Campaign

    International Nuclear Information System (INIS)

    Hodge, Chris A.

    2007-01-01

    Handheld, backpack, and mobile sensors are elements of the Global Nuclear Detection System for the interdiction and control of illicit radiological and nuclear materials. They are used by the U.S. Department of Homeland Security (DHS) and other government agencies and organizations in various roles for border protection, law enforcement, and nonproliferation monitoring. In order to systematically document the operational performance of the common commercial off-the-shelf portable radiation detection systems, the DHS Domestic Nuclear Detection Office conducted a test and evaluation campaign conducted at the Nevada Test Site from January 18 to February 27, 2006. Named 'Anole', it was the first test of its kind in terms of technical design and test complexities. The Anole test results offer users information for selecting appropriate mission-specific portable radiation detection systems. The campaign also offered manufacturers the opportunity to submit their equipment for independent operationally relevant testing to subsequently improve their detector performance. This paper will present the design, execution, and methodologies of the DHS Anole portable radiation detection system test campaign

  16. 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.

  17. Radiation Isotope Identification Device (RIIDs) Field Test and Evaluation Campaign

    International Nuclear Information System (INIS)

    Christopher Hodge, Raymond Keegan

    2007-01-01

    Handheld, backpack, and mobile sensors are elements of the Global Nuclear Detection System for the interdiction and control of illicit radiological and nuclear materials. They are used by the U.S. Department of Homeland Security (DHS) and other government agencies and organizations in various roles for border protection, law enforcement, and nonproliferation monitoring. In order to systematically document the operational performance of the common commercial off-the-shelf portable radiation detection systems, the DHS Domestic Nuclear Detection Office conducted a test and evaluation campaign conducted at the Nevada Test Site from January 18 to February 27, 2006. Named 'Anole', it was the first test of its kind in terms of technical design and test complexities. The Anole test results offer users information for selecting appropriate mission-specific portable radiation detection systems. The campaign also offered manufacturers the opportunity to submit their equipment for independent operationally relevant testing to subsequently improve their detector performance. This paper will present the design, execution, and methodologies of the DHS Anole portable radiation detection system test campaign

  18. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives

    International Nuclear Information System (INIS)

    Contado, Catia; Ravani, Laura; Passarella, Martina

    2013-01-01

    Graphical abstract: -- Highlights: •Four types of SiO 2 particles were characterized by SdFFF, PCS and EM techniques. •Clusters of 10 nm nanoparticles were found in some SiO 2 samples. •A method was set up to extract SiO 2 particles from food matrices. •The effects of the carrier solution composition on SdFFF separations were evaluated. •Particle size distributions were obtained from SiO 2 particles extracted from foodstuffs. -- Abstract: Four types of SiO 2 , available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w −1 ) a nearly silica-free instant barley coffee powder with a known SiO 2 sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO 2 particles and verify the new particle size distribution. The SiO 2 content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w −1 ). The protocol to isolate the silica particles was so applied to the most SiO 2 -rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification

  19. Locally Targeted Delivery of a Micron-Size Radiation Therapy Source Using Temperature-Sensitive Hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yusung, E-mail: yusung-kim@uiowa.edu [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Seol, Dong Rim [Department of Orthopaedic Surgery, The University of Iowa, Iowa City, Iowa (United States); Mohapatra, Sucheta [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa (United States); Sunderland, John J. [Department of Radiology, The University of Iowa, Iowa City, Iowa (United States); Schultz, Michael K. [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Department of Radiology, The University of Iowa, Iowa City, Iowa (United States); Domann, Frederick E. [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Department of Surgery, The University of Iowa, Iowa City, Iowa (United States); Lim, Tae-Hong [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa (United States)

    2014-04-01

    Purpose: To propose a novel radiation therapy (RT) delivery modality: locally targeted delivery of micron-size RT sources by using temperature-sensitive hydrogel (RT-GEL) as an injectable vehicle. Methods and Materials: Hydrogel is a water-like liquid at room temperature but gels at body temperature. Two US Food and Drug Administration-approved polymers were synthesized. Indium-111 (In-111) was used as the radioactive RT-GEL source. The release characteristics of In-111 from polymerized RT-GEL were evaluated. The injectability and efficacy of RT-GEL delivery to human breast tumor were tested using animal models with control datasets of RT-saline injection. As proof-of-concept studies, a total of 6 nude mice were tested by injecting 4 million tumor cells into their upper backs after a week of acclimatization. Three mice were injected with RT-GEL and 3 with RT-saline. Single-photon emission computed tomography (SPECT) and CT scans were performed on each mouse at 0, 24, and 48 h after injection. The efficacy of RT-GEL was determined by comparison with that of the control datasets by measuring kidney In-111 accumulation (mean nCi/cc), representing the distant diffusion of In-111. Results: RT-GEL was successfully injected into the tumor by using a 30-gauge needle. No difficulties due to polymerization of hydrogel during injection and intratumoral pressure were observed during RT-GEL injection. No back flow occurred for either RT-GEL or RT-saline. The residual tumor activities of In-111 were 49% at 24 h (44% at 48 h, respectively) for RT-GEL and 29% (22%, respectively) for RT-saline. Fused SPECT-CT images of RT-saline showed considerable kidney accumulation of In-111 (2886%, 261%, and 262% of RT-GEL at 0, 24, and 48 h, respectively). Conclusions: RT-GEL was successfully injected and showed much higher residual tumor activity: 170% (200%, respectively), than that of RT-saline at 24 h (48 h, respectively) after injection with a minimal accumulation of In-111 to the

  20. Optical measurement of acoustic radiation pressure of the near-field acoustic levitation through transparent object

    OpenAIRE

    Nakamura, Satoshi; Furusawa, Toshiaki; Sasao, Yasuhiro; Katsura, Kogure; Naoki, Kondo

    2013-01-01

    It is known that macroscopic objects can be levitated for few to several hundred micrometers by near-field acoustic field and this phenomenon is called near-field acoustic levitation (NFAL). Although there are various experiments conducted to measure integrated acoustic pressure on the object surface, up to now there was no direct method to measure pressure distribution. In this study we measured the acoustic radiation pressure of the near-field acoustic levitation via pressure-sensitive paint.

  1. Behaviour parameters of rats in the 'Open field' test under combined effect of radiation and non-radiation factors

    International Nuclear Information System (INIS)

    Kadukova, E.M.; Stashkevich, D.G.; Naumov, A.D.; Kuts, F.I.

    2015-01-01

    It was shown that exposure of electromagnetic radiation and emotional stress modifies the level of integrative reaction of CNS rats which were exposed to ionizing radiation in the 'Open field' test. (authors)

  2. In situ assembly states of (Na+,K+)-pump ATPase in human erythrocytes. Radiation target size analyses

    International Nuclear Information System (INIS)

    Hah, J.; Goldinger, J.M.; Jung, C.Y.

    1985-01-01

    The in situ assembly state of the (Na+,K+)-pump ATPase of human erythrocytes was studied by applying the classical target theory to radiation inactivation data of the ouabain-sensitive sodium efflux and ATP hydrolysis. Erythrocytes and their extensively washed white ghosts were irradiated at -45 to -50 degrees C with an increasing dose of 1.5-MeV electron beam, and after thawing, the Na+-pump flux and/or enzyme activities were assayed. Each activity measured was reduced as a simple exponential function of radiation dose, from which a radiation sensitive mass (target size) was calculated. When intact cells were used, the target sizes for the pump and for the ATPase activities were equal and approximately 620,000 daltons. The target size for the ATPase activity was reduced to approximately 320,000 daltons if the cells were pretreated with digitoxigenin. When ghosts were used, the target size for the ATPase activity was again approximately 320,000 daltons. Our target size measurements together with other information available in literature suggest that (Na+,K+)-pump ATPase may exist in human erythrocytes either as a tetramer of alpha beta or as a dimer of alpha beta in tight association with other protein mass, probably certain glycolytic enzymes, and that this tetrameric or heterocomplex association is dissociable by digitoxigenin treatment or by extensive wash during ghost preparation

  3. INSREC: Computational System for Quantitative Analysis of Radiation Effects Covering All Radiation Field

    International Nuclear Information System (INIS)

    Dong Hoon Shin; Young Wook Lee; Young Ho Cho; Hyun Seok Ko; SukHoon Kim; YoungMin Kim; Chang Sun Kang

    2006-01-01

    In the nuclear energy field, there are so many difficult things that even people who are working in this field are not much familiar with, such as, Dose evaluation, Dose management, etc. Thus, so many efforts have been done to achieve the knowledge and data for understanding. Although some data had been achieved, the applications of these data to necessary cases were more difficult job. Moreover, the type of Dose evaluation program until now was 'Console type' which is not easy enough to use for the beginners. To overcome the above causes of difficulties, the window-based integrated program and database management were developed in our research lab. The program, called as INSREC, consists of four sub-programs as follow; INSREC-NOM, INSREC-ACT, INSREC-MED, and INSREC-EXI. In ICONE 11 conference, INSREC-program(ICONE-36203) which can evaluates on/off-site dose of nuclear power plant in normal operation was introduced. Upgraded INSREC-program which will be presented in ICONE 14 conference has three additional codes comparing with pre-presented INSREC-program. Those subprograms can evaluate on/off-site Dose of nuclear power plant in accident cases. And they also have the functions of 'Dose evaluation and management' in the hospital and provide the 'Expert system' based on knowledge related to nuclear energy/radiation field. The INSREC-NOM, one of subprograms, is composed of 'Source term evaluation program', 'Atmospheric diffusion factor evaluation program', 'Off-site dose evaluation program', and 'On-site database program'. The INSREC-ACT is composed of 'On/Off-site dose evaluation program' and 'Result analysis program' and the INSREC-MED is composed of 'Workers/patients dose database program' and 'Dose evaluation program for treatment room'. The final one, INSREC-EXI, is composed of 'Database searching program based on artificial intelligence', 'Instruction program,' and 'FAQ/Q and A boards'. Each program was developed by using of Visual C++, Microsoft Access mainly

  4. Characterisation of micro-sized and nano-sized tungsten oxide-epoxy composites for radiation shielding of diagnostic X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Noor Azman, N.Z. [Department of Imaging and Applied Physics, Curtin University, GPO Box U1987, Perth, WA 6845 Australia (Australia); School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Siddiqui, S.A. [Department of Imaging and Applied Physics, Curtin University, GPO Box U1987, Perth, WA 6845 Australia (Australia); Low, I.M., E-mail: j.low@curtin.edu.au [Department of Imaging and Applied Physics, Curtin University, GPO Box U1987, Perth, WA 6845 Australia (Australia)

    2013-12-01

    Characteristics of X-ray transmissions were investigated for epoxy composites filled with 2–10 vol% WO{sub 3} loadings using synchrotron X-ray absorption spectroscopy (XAS) at 10–40 keV. The results obtained were used to determine the equivalent X-ray energies for the operating X-ray tube voltages of mammography and radiology machines. The results confirmed the superior attenuation ability of nano-sized WO{sub 3}-epoxy composites in the energy range of 10–25 keV when compared to their micro-sized counterparts. However, at higher synchrotron radiation energies (i.e., 30–40 keV), the X-ray transmission characteristics were similar with no apparent size effect for both nano-sized and micro-sized WO{sub 3}-epoxy composites. The equivalent X-ray energies for the operating X-ray tube voltages of the mammography unit (25–49 kV) were in the range of 15–25 keV. Similarly, for a radiology unit operating at 40–60 kV, the equivalent energy range was 25–40 keV, and for operating voltages greater than 60 kV (i.e., 70–100 kV), the equivalent energy was in excess of 40 keV. The mechanical properties of epoxy composites increased initially with an increase in the filler loading but a further increase in the WO{sub 3} loading resulted in deterioration of flexural strength, modulus and hardness. - Highlights: • Nano-sized WO{sub 3}-epoxy composites have superior x-ray shielding capability. • No size effect in x-ray attenuation was observed at 30–40 keV. • An optimum filler loading for improving the mechanical properties of WO{sub 3}-epoxy composites.

  5. Magnetophoresis behaviour at low gradient magnetic field and size control of nickel single core nanobeads

    Energy Technology Data Exchange (ETDEWEB)

    Benelmekki, M., E-mail: benelmekki@fisica.uminho.p [Centro de Fisica, Universidade do Minho, Braga (Portugal); Montras, A. [Sepmag Tecnologies, Parc Tecnologic del Valles, Barcelona (Spain); Martins, A.J.; Coutinho, P.J.G. [Centro de Fisica, Universidade do Minho, Braga (Portugal); Martinez, Ll.M. [Sepmag Technologies, Atlanta, GA (United States)

    2011-08-15

    Magnetic separation of organic compounds, proteins, nucleic acids and other biomolecules, and cells from complex reaction mixtures is becoming the most suitable solution for large production in bioindustrial purification and extraction processes. Optimal magnetic properties can be achieved by the use of metals. However, they are extremely sensitive to oxidation and degradation under atmospheric conditions. In this work Ni nanoparticles are synthesised by conventional solution reduction process with the addition of a non-ionic surfactant as a surface agent. The nanoparticles were surfacted in citric acid and then coated with silica to form single core Ni nanobeads. A magnetophoresis study at different magnetic field gradients and at the different steps of synthesis route was performed using Horizontal Low Gradient Magnetic Field (HLGMF) systems. The reversible aggregation times are reduced to a few seconds, allowing a very fast separation process. - Research highlights: Monodispersed single core Ni-silica core-shell structures were prepared. Control of Ni nanoparticles size was achieved using a non-ionic surfactant. Magnetophoresis at different magnetic field gradients was monitored. Magnetophoresis at different steps of synthesis route was performed. Attractive magnetic interactions overcome electrostatic repulsions.

  6. Particle size dependence of zero-field microwave absorption in powdered Bi-Sr-Ca-Cu-O superconductors

    CERN Document Server

    Topacli, C

    1997-01-01

    The non-resonant magnetically modulated microwave response measurements of powdered Bi-Sr-Ca-Cu-O samples using the conventional EPR spectrometer are presented. After cooling in a near zero magnetic field, all samples exhibited a sharp (about 12-37 mu T) microwave absorption with applied magnetic field, superimposed on the widely observed and well explained broader minimum. The width of the absorption maximum is found to be dependent on the particle size. It becomes broader with decreasing particle size. The effects of particle size and field history on the peak are given in detail and some possible mechanisms to account for the observations are presented. (author)

  7. The role of Swedish Radiation Protection Authority in the field of public health

    International Nuclear Information System (INIS)

    Cederlund, Torsten; Finck, Robert; Mjoenes, Lars; Moberg, Leif; Soederman, Ann-Louis; Wiklund, Aasa; Yuen Katarina; Oelander Guer, Hanna

    2004-09-01

    The Swedish Government has requested the Swedish Radiation Protection Authority (SSI) to make an account of the authority's role in the field of public health. Radiation Protection consists largely of preventive actions in order to protect man and the environment against harmful effects of radiation. The SSI thus considers most of the authority's activities to be public health related. The report describes a number of radiation protection areas from a health perspective. The measures taken by the authority in these areas are also described along with planned activities. In some areas the authority also points out additional measures

  8. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats ?

    OpenAIRE

    Mohammed, Haitham S.; Fahmy, Heba M.; Radwan, Nasr M.; Elsayed, Anwar A.

    2012-01-01

    In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susc...

  9. Spectral tuning of near-field radiative heat transfer by graphene-covered metasurfaces

    Science.gov (United States)

    Zheng, Zhiheng; Wang, Ao; Xuan, Yimin

    2018-03-01

    When two gratings are respectively covered by a layer of graphene sheet, the near-field radiative heat transfer between two parallel gratings made of silica (SiO2) could be greatly improved. As the material properties of doped silicon (n-type doping concentration is 1020 cm-3, marked as Si-20) and SiO2 differ greatly, we theoretically investigate the near-field radiative heat transfer between two parallel graphene-covered gratings made of Si-20 to explore some different phenomena, especially for modulating the spectral properties. The radiative heat flux between two parallel bulks made of Si-20 can be enhanced by using gratings instead of bulks. When the two gratings are respectively covered by a layer of graphene sheet, the radiative heat flux between two gratings made of Si-20 can be further enhanced. By tuning graphene chemical potential μ and grating filling factor f, due to the interaction between surface plasmon polaritons (SPPs) of graphene sheets and grating structures, the spectral properties of the radiative heat flux between two parallel graphene-covered gratings can be effectively regulated. This work will develop and supplement the effects of materials on the near-field radiative heat transfer for this kind of system configuration, paving a way to modulate the spectral properties of near-field radiative heat transfer.

  10. LET spectrometry with track etch detectors-Use in high-energy radiation fields

    International Nuclear Information System (INIS)

    Jadrnickova, I.; Spurny, F.

    2008-01-01

    For assessing the risk from ionizing radiation it is necessary to know not only the absorbed dose but also the quality of the radiation; radiation quality is connected with the physical quantity linear energy transfer (LET). One of the methods of determination of LET is based on chemically etched track detectors. This contribution concerns with a spectrometer of LET based on the track detectors and discusses some results obtained at: ·high-energy radiation reference field created at the SPS accelerator at CERN; and ·onboard of International Space Station where track-etch based LET spectrometer has been exposed 273 days during 'Matrjoshka - R' experiment. Results obtained are compared with the results of studies at some lower-energy neutron sources; some conclusions on the registrability of neutrons and the ability of this spectrometer to determine dose equivalent in high-energy radiation fields are formulated

  11. Radiation Fields in High Energy Accelerators and their impact on Single Event Effects

    CERN Document Server

    García Alía, Rubén; Wrobel, Frédéric; Brugger, Markus

    Including calculation models and measurements for a variety of electronic components and their concerned radiation environments, this thesis describes the complex radiation field present in the surrounding of a high-energy hadron accelerator and assesses the risks related to it in terms of Single Event Effects (SEE). It is shown that this poses not only a serious threat to the respective operation of modern accelerators but also highlights the impact on other high-energy radiation environments such as those for ground and avionics applications. Different LHC-like radiation environments are described in terms of their hadron composition and energy spectra. They are compared with other environments relevant for electronic component operation such as the ground-level, avionics or proton belt. The main characteristic of the high-energy accelerator radiation field is its mixed nature, both in terms of hadron types and energy interval. The threat to electronics ranges from neutrons of thermal energies to GeV hadron...

  12. Relativistic nonlinear electrodynamics the QED vacuum and matter in super-strong radiation fields

    CERN Document Server

    Avetissian, Hamlet K

    2016-01-01

    This revised edition of the author’s classic 2006 text offers a comprehensively updated review of the field of relativistic nonlinear electrodynamics. It explores the interaction of strong and super-strong electromagnetic/laser radiation with the electromagnetic quantum vacuum and diverse types of matter – including free charged particles and antiparticles, acceleration beams, plasma and plasmous media.  The appearance of laser sources of relativistic and ultra-relativistic intensities over the last decade has stimulated investigation of a large class of processes under such super-strong radiation fields. Revisions for this second edition reflect these developments and the book includes new chapters on Bremsstrahlung and nonlinear absorption of superintense radiation in plasmas, the nonlinear interaction of relativistic atoms with intense laser radiation, nonlinear interaction of strong laser radiation with Graphene, and relativistic nonlinear phenomena in solid-plasma targets under supershort laser pul...

  13. The need of education of biotechnical specialists in the field of radiation protection

    International Nuclear Information System (INIS)

    Kljajic, R.; Masic, Z.; Mitrovic, R.; Petrovic, B.

    1996-01-01

    Education is the base for a successful carrying out of radiation protection measures. Starting from this fact, in the field of biotechnology protection measures should be carried out by biotechnical specialists (veterinarians, agronomists, technologists). In FR Yugoslavia, at the Faculty of Veterinary Medicine a separate course 'Radiobiology and radiation hygiene' was introduced in undergraduate and postgraduate studies m 1976. However, other biotechnological specialists do not study the field of radiation protection separately at their faculties. Because of this, the Expert Group for Radiation Protection in Biotechnology formed at the Federal Ministry of Economy initiated the introducing of a course for this held m undergraduate and postgraduate studies at the faculties of agriculture and technology in FR Yugoslavia. This paper presents the basic elements of the educational plan and program of the course 'Radiobiology and radiation hygiene' for students of biotechnical faculties in FR Yugoslavia and discusses the results obtained until now. (author)

  14. Development of a prototype radiation surveillance equipment for a mid-sized unmanned aerial vehicle

    International Nuclear Information System (INIS)

    Smolander, P.; Kurvinen, K.; Poellaenen, R.; Kettunen, M.; Lyytinen, J.

    2003-01-01

    A prototype radiation surveillance equipment has been developed to be used in a mid-sized Ranger unmanned aerial vehicle (UAV) acquired by the Finnish Defence Forces. A multi-detector assembly was designed for the acquisition of dose rate and radionuclide concentration in the release plume. Detector assembly includes a GM-tube based dose rate meter, an inorganic scintillator detector and a semiconductor detector operating at room temperature. A sampling unit was designed for the collection of an aerosol sample of the plume for a detailed analysis in a ground based laboratory. The measurement data from all three detectors and several environmental parameters are collected by the onboard data acquisition computer. Real-time data dissemination is implemented with a TETRA based radio network. Test flights have been carried out with target drones and a small manned airplane. The Northrop KD2R-5 target drones have been used to simulate the high-G launch and vibration environment of the Ranger aerial vehicle. Target drones have been used because their air vehicle classification allows small test packages to be installed without tedious air safety protocols. Stability and survivability of the detectors, GPS navigation and radio frequency communication have been studied with the target drone test flights. Ground station software was developed to visualise the measurement data and to track the position of the air vehicle on a digital map. Test flights with the small manned airplane have been used to study the operational aspects of the detectors with greater detail. The housing for the instruments has been designed and constructed based on the experiences gained with the test flights and the laboratory measurements. The housing satisfies the aviation authority standards. Special attention has been paid to the high modularity, quick installation and ease of use. (orig.)

  15. Development of a prototype radiation surveillance equipment for a mid-sized unmanned aerial vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Smolander, P.; Kurvinen, K.; Poellaenen, R. [Radiation and Nuclear Safety Authority, Helsinki (Finland); Kettunen, M. [Forces Research Institute of Technology, Lakiala (Finland); Lyytinen, J. [Helsinki University of Technology, Laboratory of Lightweight Structures, Otaniemi (Finland)

    2003-06-01

    A prototype radiation surveillance equipment has been developed to be used in a mid-sized Ranger unmanned aerial vehicle (UAV) acquired by the Finnish Defence Forces. A multi-detector assembly was designed for the acquisition of dose rate and radionuclide concentration in the release plume. Detector assembly includes a GM-tube based dose rate meter, an inorganic scintillator detector and a semiconductor detector operating at room temperature. A sampling unit was designed for the collection of an aerosol sample of the plume for a detailed analysis in a ground based laboratory. The measurement data from all three detectors and several environmental parameters are collected by the onboard data acquisition computer. Real-time data dissemination is implemented with a TETRA based radio network. Test flights have been carried out with target drones and a small manned airplane. The Northrop KD2R-5 target drones have been used to simulate the high-G launch and vibration environment of the Ranger aerial vehicle. Target drones have been used because their air vehicle classification allows small test packages to be installed without tedious air safety protocols. Stability and survivability of the detectors, GPS navigation and radio frequency communication have been studied with the target drone test flights. Ground station software was developed to visualise the measurement data and to track the position of the air vehicle on a digital map. Test flights with the small manned airplane have been used to study the operational aspects of the detectors with greater detail. The housing for the instruments has been designed and constructed based on the experiences gained with the test flights and the laboratory measurements. The housing satisfies the aviation authority standards. Special attention has been paid to the high modularity, quick installation and ease of use. (orig.)

  16. An estimate of radiation fields in a gamma irradiation facility using fuel elements from a swimming pool reactor

    International Nuclear Information System (INIS)

    Narain, Rajendra

    2002-01-01

    A simple gamma irradiation facility set up using a few irradiated or partially irradiated swimming pool elements can be assembled to provide a convenient facility for irradiation of small and medium sized samples for research. The paper presents results of radiation levels with an arrangement using four elements from a reactor core operating at a power of 20 MW. A maximum gamma field of higher than 1 KGy/h at locations adjacent to fuel elements with negligible neutron contamination can be achieved. (author)

  17. Reduction in life span on normal human fibroblasts exposed to low-dose radiation in heavy-ion radiation field

    International Nuclear Information System (INIS)

    Suzuki, Masao; Yamaguchi, Chizuru; Yasuda, Hiroshi; Uchihori, Yukio; Fujitaka, Kazunobu

    2003-01-01

    We studied the effect of in vitro life span in normal human fibroblasts exposed to chronically low-dose radiation in heavy-ion radiation field. Cells were cultured in a CO 2 incubator, which was set in the irradiation room for biological study of heavy ions in the Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS), and exposed to scattered radiations produced with heavy-ion beams throughout the life span of the cell population. Absorbed dose, which was measured using a thermoluminescence dosimeter(TLD) and a Si-semiconductor detector, was to be 1.4 mGy per day when operating the HIMAC machine for biological experiments. The total population doubling number of the exposed cells reduced to 79-93% of non-exposed control cells in the three independent experiments. There is evidence that the exposure of chronically low-dose radiation in heavy-ion radiation field promotes the life-span reduction in cellular level. (author)

  18. Near-field radiative heat transfer between clusters of dielectric nanoparticles

    International Nuclear Information System (INIS)

    Dong, J.; Zhao, J.M.; Liu, L.H.

    2017-01-01

    In this work, we explore the near-field radiative heat transfer between two clusters of silicon carbide (SiC) nanoparticles using the many-body radiative heat transfer theory. The effects of fractal dimension of clusters, many-body interaction between nanoparticles and relative orientation of clusters on the thermal conductance are studied. Meanwhile, the applicability of the equivalent volume spheres (EVS) approximation for near-field radiative heat transfer between clusters is examined. It is observed that the thermal conductance is larger for clusters with larger fractal dimension, which is more significant in the near-field. The thermal conductance of EVS resembles that of the clusters, but EVS overestimates the conductance of clusters, especially in the near-field. Compared to the case of two nanoparticles, the conductance of nanoparticle clusters decays much slower with increasing distance in the near-field, but shares similar dependence on the distance in the far-field. The thermal conductance of SiC nanoparticle clusters is inhibited by the many-body interaction when surface phonon polariton is supported but enhanced at frequencies close to the resonance frequency. The total thermal conductance is decreased due to many-body interaction among particles in the cluster. The relative orientation between the clusters is also an important factor in the near-field, especially for clusters with lower fractal dimension. - Highlights: • Near-field radiative heat transfer between clusters of nanoparticles is studied. • The many-body radiative heat transfer theory is applied for rigorous analysis. • The accuracy of equivalent volume spheres approximation is examined. • Clusters with larger fractal dimension have larger radiative thermal conductance. • Many-body interaction inhibits the total radiative thermal conductance.

  19. Electronic radiation of a plasma in a magnetic field

    International Nuclear Information System (INIS)

    Canobbio, E.; Consoli, T.; Ichtchenko, G.; Parlance, F.

    1965-01-01

    The influence on the microwave spectrum of the number of fast electrons, density, pressure and plasma inhomogeneities, has been studied in a hot cathode reflex discharge, operating either in a steady state either in a pulsed regime. Under some conditions a strong emission is observed between the harmonics of the electron gyrofrequency. A theoretical interpretation of the results is advanced by extending a model already proposed by CANOBBIO and CROCI. In particular it is indicated that the transition radiation can be responsible for the emission observed between the harmonics. (authors) [fr

  20. Use of thermoluminescent dosimetry in gamma radiation fields studies

    International Nuclear Information System (INIS)

    Carron, W.

    1987-01-01

    The depth-dose curves for gamma rays in material of interest to agronomy were obtained using lithium fluoride thermoluminescent dosimeters. The dose conversion factors for LiF were determined from curves of the absorved dose versus depth in water, wood and soil. Mathematics equations were chosen to best fit these curves. In the view of the results we came to the conclusion that in the studied materials the absorved radiation dose presents a great variation to the depth and could be correlated through of the exponential regression. (author)

  1. Predictions of integrated circuit serviceability in space radiation fields

    Energy Technology Data Exchange (ETDEWEB)

    Khamidullina, N.M.; Kuznetsov, N.V.; Pichkhadze, K.M.; Popov, V.D

    1999-10-01

    The present paper suggests an approach to estimating and predicting the serviceability of on-board electronic equipment. It is based on the postulates of the reliability theory and accounts for total-dose and single-event radiation effects as well as other exterior destabilizing factors. The methods of determination of failure and upset rates for CMOS devices are considered. The probability of non-failure operation of a two CMOS RAM is calculated along the whole trajectory of the 'Solar Probe' spacecraft.

  2. Quantum theory of laser radiation scattering by electrons in magnetic fields

    International Nuclear Information System (INIS)

    Rochlin, H.; Davidovich, L.

    1982-01-01

    A system consisting of an electron in a static magnetic field, interacting with the quantized electromagnetic field, within the non-relativistic and electric dipole approximations (with a cutoff in momentum space) is considered. The Heisenberg equations of motion are solved exactly and the time evolution of the electric field is determined. The power spectrum of the scattered radiation is calculated, when the electromagnetic field is initially in a coherent state. The results for the line shape of the scattered radiation are shown to be valid for magnetic fields up to 10 12 G. The quantization of the electromagnetic field allows one to consider effects of the natural linewidth and its dependence on the magnetic field. The renormalization of the electron mass is included in these treatment, and the results remain finite when the cutoff goes to infinity. (Author) [pt

  3. Experiments performed with a functional model based on statistical discrimination in mixed nuclear radiation field

    International Nuclear Information System (INIS)

    Valcov, N.; Celarel, A.; Purghel, L.

    1999-01-01

    By using the statistical discrimination technique, the components of on ionization current, due to a mixed radiation field, may be simultaneously measured. A functional model, including a serially manufactured gamma-ray ratemeter was developed, as an intermediate step in the design of specialised nuclear instrumentation, in order to check the concept of statistical discrimination method. The obtained results are in good agreement with the estimations of the statistical discrimination method. The main characteristics of the functional model are the following: - dynamic range of measurement: >300: l; - simultaneous measurement of natural radiation background and gamma-ray fields; - accuracy (for equal exposure rates from gamma's and natural radiation background): 17%, for both radiation fields; - minimum detectable exposure rate: 2μR/h. (authors)

  4. Exploring graphene field effect transistor devices to improve spectral resolution of semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Richard Karl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen Wayne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Jeffrey B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hamilton, Allister B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-12-01

    Graphene, a planar, atomically thin form of carbon, has unique electrical and material properties that could enable new high performance semiconductor devices. Graphene could be of specific interest in the development of room-temperature, high-resolution semiconductor radiation spectrometers. Incorporating graphene into a field-effect transistor architecture could provide an extremely high sensitivity readout mechanism for sensing charge carriers in a semiconductor detector, thus enabling the fabrication of a sensitive radiation sensor. In addition, the field effect transistor architecture allows us to sense only a single charge carrier type, such as electrons. This is an advantage for room-temperature semiconductor radiation detectors, which often suffer from significant hole trapping. Here we report on initial efforts towards device fabrication and proof-of-concept testing. This work investigates the use of graphene transferred onto silicon and silicon carbide, and the response of these fabricated graphene field effect transistor devices to stimuli such as light and alpha radiation.

  5. Use of an electric field in an electrostatic liquid film radiator.

    Science.gov (United States)

    Bankoff, S G; Griffing, E M; Schluter, R A

    2002-10-01

    Experimental and numerical work was performed to further the understanding of an electrostatic liquid film radiator (ELFR) that was originally proposed by Kim et al.(1) The ELFR design utilizes an electric field that exerts a normal force on the interface of a flowing film. The field lowers the pressure under the film in a space radiator and, thereby, prevents leakage through a puncture in the radiator wall. The flowing film is subject to the Taylor cone instability, whereby a cone of fluid forms underneath an electrode and sharpens until a jet of fluid is pulled toward the electrode and disintegrates into droplets. The critical potential for the instability is shown to be as much as an order of magnitude higher than that used in previous designs.(2) Furthermore, leak stoppage experiments indicate that the critical field is adequate to stop leaks in a working radiator.

  6. Study of extremely low frequency electromagnetic field (ELF EMF) radiation produced by consumer products

    International Nuclear Information System (INIS)

    Roha Tukimin; Ahmad Fazli Ahmad Sanusi; Rozaimah Abd Rahim; Mohd Yusof Mohd Ali; Mohamad Amirul Nizam Mohamad Thari

    2006-01-01

    Extremely low frequency electromagnetic field ( ELF EMF) radiation falls under category of non-ionising radiation (NIR).ELF EMF consists of electric and magnetic fields. Excessive exposure to ELF EMF radiation may cause biological and health effects to human beings such as behavioral changes, stochastic and as initiator of cancer. In daily life, the main source of extremely low frequency electromagnetic radiation are consumer products in our home and office. Due to its ability to cause hazard, a study of ELF EMF radiation produced by consumer product was conducted. For this preliminary study, sample of 20 types electrical appliances were selected. The measurement was covered electric and magnetic field strength produced by the sample. PMM model EHP50A were used for measurement and data analysis. The results were compared with the permissible limits recommended by International Commission of Non-Ionising Radiation Protection (ICNIRP) for members of public (1000 mGauss and 5000 V/m). The results showed that all tested sample produced magnetic and electric field but still under the permissible limit recommended by ICNIRP. Besides that we found that field strengths can be very high at closer distance to the sample. (Author)

  7. The Effect of Grain Size on the Radiation Response of Silicon Carbide and its Dependence on Irradiation Species and Temperature

    Science.gov (United States)

    Jamison, Laura

    In recent years the push for green energy sources has intensified, and as part of that effort accident tolerant and more efficient nuclear reactors have been designed. These reactors demand exceptional material performance, as they call for higher temperatures and doses. Silicon carbide (SiC) is a strong candidate material for many of these designs due to its low neutron cross-section, chemical stability, and high temperature resistance. The possibility of improving the radiation resistance of SiC by reducing the grain size (thus increasing the sink density) is explored in this work. In-situ electron irradiation and Kr ion irradiation was utilized to explore the radiation resistance of nanocrystalline SiC (nc-SiC), SiC nanopowders, and microcrystalline SiC. Electron irradiation simplifies the experimental results, as only isolated Frenkel pairs are produced so any observed differences are simply due to point defect interactions with the original microstructure. Kr ion irradiation simulates neutron damage, as large radiation cascades with a high concentration of point defects are produced. Kr irradiation studies found that radiation resistance decreased with particle size reduction and grain refinement (comparing nc-SiC and microcrystalline SiC). This suggests that an interface-dependent amorphization mechanism is active in SiC, suggested to be interstitial starvation. However, under electron irradiation it was found that nc-SiC had improved radiation resistance compared to single crystal SiC. This was found to be due to several factors including increased sink density and strength and the presence of stacking faults. The stacking faults were found to improve radiation response by lowering critical energy barriers. The change in radiation response between the electron and Kr ion irradiations is hypothesized to be due to either the change in ion type (potential change in amorphization mechanism) or a change in temperature (at the higher temperatures of the Kr ion

  8. Radiation field analyses in reactor vessels of PWRs

    Energy Technology Data Exchange (ETDEWEB)

    Fukuya, Koji; Nakata, Hayato; Fujii, Katsuhiko; Kimura, Itsuro [Institute of Nuclear Safety System, Inc., Mihama, Fukui (Japan); Ohmura, Masaki; Kitagawa, Hideo [Mitsubishi Heavy Industries, Ltd., Nuclear Energy Systems Engineering Center, Yokohama, Kanagawa (Japan); Itoh, Taku; Shin, Kazuo [Kyoto Univ. (Japan). Faculty of Engineering

    2002-09-01

    Radiation analysis in reactor vessels of PWRs were performed using three calculation codes (two dimensional transport code DORT, three dimensional transport code TORT and three dimensional Monte Carlo code MCNP) and three cross section data (ENDF/B-IV, ENDF/B-VI and JENDL3.2) to improve accuracy of estimation for neutron flux, gamma-ray flux and displacement per atom (dpa). The calculations using DORT at a surveillance position agreed with the dosimetry measurements for the three cross sections. The calculated neutron spectra using the three cross sections at the reactor vessels and the surveillance position were quite similar to each other. The difference in the cross sections gave small impacts on the fluence estimation. The ratio of the calculations to the measurements using TORT was similar to those using DORT, indicating that TORT is applicable to the radiation analysis in PWRs. The MCNP calculations resulted in a similar agreement with the dosimeter measurement to the DORT calculation while they needed a long computing time. Improvement of calculation techniques is needed for application of MCNP. The calculated dpa agreed within 10% for the three cross sections. (author)

  9. Effect of pulsed electric fields treatment and mash size on extraction and composition of apple juices.

    Science.gov (United States)

    Turk, Mohammad F; Baron, Alain; Vorobiev, Eugene

    2010-09-08

    This study explored the effect of pulsed electric field (PEF) treatment (E=450 V/cm; tt=10 ms; Eapple mash size on juice yield, polyphenolic compounds, sugars, and malic acid. Juice yield increased significantly after PEF treatment of large mash (Y=71.4%) and remained higher than the juice yield obtained for a control small mash (45.6%). The acid sweet balance was not altered by PEF. A correlation was established between the decrease of light absorbance (control: 1.43; treated: 1.10) and the decline of native polyphenols yield due to PEF treatment (control: 9.6%; treated: 5.9% for small mash). An enhanced oxidation of phenolic compounds in cells due to electroporation of the inner cell membrane and the adsorption of the oxidized products on the mash may explain both the lower light absorbance and the lower native polyphenol concentration.

  10. Roundup Ready soybean gene concentrations in field soil aggregate size classes.

    Science.gov (United States)

    Levy-Booth, David J; Gulden, Robert H; Campbell, Rachel G; Powell, Jeff R; Klironomos, John N; Pauls, K Peter; Swanton, Clarence J; Trevors, Jack T; Dunfield, Kari E

    2009-02-01

    Roundup Ready (RR) soybeans containing recombinant Agrobacterium spp. CP4 5-enol-pyruvyl-shikimate-3-phosphate synthase (cp4 epsps) genes tolerant to the herbicide glyphosate are extensively grown worldwide. The concentration of recombinant DNA from RR soybeans in soil aggregates was studied due to the possibility of genetic transformation of soil bacteria. This study used real-time PCR to examine the concentration of cp4 epsps in four field soil aggregate size classes (>2000 microm, 2000-500 microm, 500-250 microm and 2000 mum fraction contained between 66.62% and 99.18% of total gene copies, although it only accounted for about 30.00% of the sampled soil. Aggregate formation may facilitate persistence of recombinant DNA.

  11. Radiation Field of a Square, Helical Beam Antenna

    DEFF Research Database (Denmark)

    Knudsen, Hans Lottrup

    1952-01-01

    square helices are used. Further, in connection with corresponding rigorous formulas for the field from a circular, helical antenna with a uniformly progressing current wave of constant amplitude the present formulas may be used for an investigation of the magnitude of the error introduced in Kraus......' approximate calculation of the field from a circular, helical antenna by replacing this antenna with an ``equivalent'' square helix. This investigation is carried out by means of a numerical example. The investigation shows that Kraus' approximate method of calculation yields results in fair agreement...

  12. submitter A High Precision 3D Magnetic Field Scanner for Small to Medium Size Magnets

    CERN Document Server

    Bergsma, F; Garnier, F; Giudici, P A

    2016-01-01

    A bench to measure the magnetic field of small to-medium-sized magnets with high precision was built. It uses a small-sized head with three orthogonal Hall probes, supported on a long pole at continuous movement during measurement. The head is calibrated in three dimensions by rotation over the full solid angle in a special device. From 0 to 2.5 T, the precision is ±0.2 mT in all components. The spatial range is 1 × 1 × 2 m with precision of ±0.02 mm. The bench and its controls are lightweight and easy to transport. The head can penetrate through small apertures and measure as close as 0.5 mm from the surface of a magnet. The bench can scan complicated grids in Cartesian or cylindrical coordinates, steered by a simple text file on an accompanying PC. The raw data is online converted to magnetic units and stored in a text file.

  13. Resonant atom-field interaction in large-size coupled-cavity arrays

    International Nuclear Information System (INIS)

    Ciccarello, Francesco

    2011-01-01

    We consider an array of coupled cavities with staggered intercavity couplings, where each cavity mode interacts with an atom. In contrast to large-size arrays with uniform hopping rates where the atomic dynamics is known to be frozen in the strong-hopping regime, we show that resonant atom-field dynamics with significant energy exchange can occur in the case of staggered hopping rates even in the thermodynamic limit. This effect arises from the joint emergence of an energy gap in the free photonic dispersion relation and a discrete frequency at the gap's center. The latter corresponds to a bound normal mode stemming solely from the finiteness of the array length. Depending on which cavity is excited, either the atomic dynamics is frozen or a Jaynes-Cummings-like energy exchange is triggered between the bound photonic mode and its atomic analog. As these phenomena are effective with any number of cavities, they are prone to be experimentally observed even in small-size arrays.

  14. Radiation reaction for the classical relativistic spinning particle in scalar, tensor and linearized gravitational fields

    International Nuclear Information System (INIS)

    Barut, A.O.; Cruz, M.G.

    1992-08-01

    We use the method of analytic continuation of the equation of motion including the self-fields to evaluate the radiation reaction for a classical relativistic spinning point particle in interaction with scalar, tensor and linearized gravitational fields in flat spacetime. In the limit these equations reduce to those of spinless particles. We also show the renormalizability of these theories. (author). 10 refs

  15. Very high-accuracy calibration of radiation pattern and gain of a near-field probe

    DEFF Research Database (Denmark)

    Pivnenko, Sergey; Nielsen, Jeppe Majlund; Breinbjerg, Olav

    2014-01-01

    In this paper, very high-accuracy calibration of the radiation pattern and gain of a near-field probe is described. An open-ended waveguide near-field probe has been used in a recent measurement of the C-band Synthetic Aperture Radar (SAR) Antenna Subsystem for the Sentinel 1 mission of the Europ...

  16. Calculation of the radiation force on a cylinder in a standing wave acoustic field

    Energy Technology Data Exchange (ETDEWEB)

    Haydock, David [Unilever R and D Colworth, Sharnbrook, Bedford MK44 1LQ (United Kingdom); Department of Physics, Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

    2005-04-15

    We present a new calculation of the radiation force on a cylinder in a standing wave acoustic field. We use the formula to calculate the force on a cylinder which is free to move in the field and one which is fixed in space.

  17. Calculation of the radiation force on a cylinder in a standing wave acoustic field

    International Nuclear Information System (INIS)

    Haydock, David

    2005-01-01

    We present a new calculation of the radiation force on a cylinder in a standing wave acoustic field. We use the formula to calculate the force on a cylinder which is free to move in the field and one which is fixed in space

  18. Effect of Photon Beam Energy, Gold Nanoparticle Size and Concentration on the Dose Enhancement in Radiation Therapy

    Directory of Open Access Journals (Sweden)

    Nahideh Gharehaghaji

    2013-02-01

    Full Text Available Introduction: Gold nanoparticles have been used as radiation dose enhancing materials in recent investigations. In the current study, dose enhancement effect of gold nanoparticles on tumor cells was evaluated using Monte Carlo (MC simulation. Methods: We used MCNPX code for MC modeling in the current study. A water phantom and a tumor region with a size of 1×1×1 cm3 loaded with gold nanoparticles were simulated. The macroscopic dose enhancement factor was calculated for gold nanoparticles with sizes of 30, 50, and 100 nm. Also, we simulated different photon beams including mono-energetic beams (50-120 keV, a Cobalt-60 beam, 6 & 18 MV photon beams of a conventional linear accelerator. Results: We found a dose enhancement factor (DEF of from 1.4 to 3.7 for monoenergetic kilovoltage beams, while the DEFs for megavoltage beams were negligible and less than 3% for all GNP sizes and concentrations. The optimum energy for higher DEF was found to be the 90 keV monoenergetic beam. The effect of GNP size was not considerable, but the GNP concentration had a substantial impact on achieved DEF in GNP-based radiation therapy. Conclusion: The results were in close agreement with some previous studies considering the effect of photon energy and GNP concentration on observed DEF. Application of GNP-based radiation therapy using kilovoltage beams is recommended.

  19. Radiative Corrections from Heavy Fast-Roll Fields during Inflation

    DEFF Research Database (Denmark)

    Jain, Rajeev Kumar; Sandora, McCullen; Sloth, Martin S.

    2015-01-01

    to an unobservable small running of the spectral index. An observable level of tensor modes can also be accommodated, but, surprisingly, this requires running to be induced by a curvaton. If upcoming observations are consistent with a small tensor-to-scalar ratio as predicted by small field models of inflation...

  20. Efficient Compression of Far Field Matrices in Multipole Algorithms based on Spherical Harmonics and Radiating Modes

    Directory of Open Access Journals (Sweden)

    A. Schroeder

    2012-09-01

    Full Text Available This paper proposes a compression of far field matrices in the fast multipole method and its multilevel extension for electromagnetic problems. The compression is based on a spherical harmonic representation of radiation patterns in conjunction with a radiating mode expression of the surface current. The method is applied to study near field effects and the far field of an antenna placed on a ship surface. Furthermore, the electromagnetic scattering of an electrically large plate is investigated. It is demonstrated, that the proposed technique leads to a significant memory saving, making multipole algorithms even more efficient without compromising the accuracy.

  1. Applicability of ambient dose equivalent H*(d) in mixed radiation fields - a critical discussion

    International Nuclear Information System (INIS)

    Hajek, M.; Vana, N.

    2004-01-01

    For purposes of routine radiation protection, it is desirable to characterize the potential irradiation of individuals in terms of a single dose equivalent quantity that would exist in a phantom approximating the human body. The phantom of choice is the ICRU sphere made of 30 cm diameter tissue-equivalent plastic with a density of 1 g.cm-3 and a mass composition of 76.2 % O, 11.1 % C, 10.1 % H and 2.6 % N. Ambient dose equivalent, H*(d), was defined in ICRU report 51 as the dose equivalent that would be produced by an expanded and aligned radiation field at a depth d in the ICRU sphere. The recommended reference depths are 10 mm for strongly penetrating radiation and 0.07 mm for weakly penetrating radiation, respectively. As an operational quantity in radiation protection, H*(d) shall serve as a conservative and directly measurable estimate of protection quantities, e.g. effective dose E, which in turn are intended to give an indication of the risk associated with radiation exposure. The situation attains increased complexity in radiation environments being composed of a variety of charged and uncharged particles in a broad energetic spectrum. Radiation fields of similarly complex nature are, for example, encountered onboard aircraft and in space. Dose equivalent was assessed as a function of depth in quasi tissue-equivalent spheres by means of thermoluminescent dosemeters evaluated according to the high-temperature ratio (HTR) method. The presented experiments were performed both onboard aircraft and the Russian space station Mir. As a result of interaction processes within the phantom body, the incident primary spectrum may be significantly modified with increasing depth. For the radiation field at aviation altitudes we found the maximum of dose equivalent in a depth of 60 mm which conflicts with the 10 mm value recommended by ICRU. Contrary, for the space radiation environment the maximum dose equivalent was found at the surface of the sphere. This suggests that

  2. Applicability of Ambient Dose Equivalent H (d) in Mixed Radiation Fields - A Critical Discussion

    International Nuclear Information System (INIS)

    Vana, R.; Hajek, M.; Bergerm, T.

    2004-01-01

    For purposes of routine radiation protection, it is desirable to characterize the potential irradiation of individuals in terms of a single dose equivalent quantity that would exist in a phantom approximating the human body. The phantom of choice is the ICRU sphere made of 30 cm diameter tissue-equivalent plastic with a density of 1 g/cm3 and a mass composition of 76.2% O, 11.1% C, 10.1% H and 2.6% N. Ambient dose equivalent, H(d), was defined in ICRU report 51 as the dose equivalent that would be produced by an expanded and aligned radiation field at a depth d in the ICRU sphere. The recommended reference depths are 10 mm for strongly penetrating radiation and 0.07 mm for weakly penetrating radiation, respectively. As an operational quantity in radiation protection, H(d) shall serve as a conservative and directly measurable estimate of protection quantities, e.g. effective dose E, which in turn are intended to give an indication of the risk associated with radiation exposure. The situation attains increased complexity in radiation environments being composed of a variety of charged and uncharged particles in a broad energetic spectrum. Radiation fields of similarly complex nature are, for example, encountered onboard aircraft and in space. Dose equivalent was assessed as a function of depth in quasi tissue-equivalent spheres by means of thermoluminescent dosemeters evaluated according to the high-temperature ratio (HTR) method. The presented experiments were performed both onboard aircraft and the Russian space station Mir. As a result of interaction processes within the phantom body, the incident primary spectrum may be significantly modified with increasing depth. For the radiation field at aviation altitudes we found the maximum of dose equivalent in a depth of 60 mm which conflicts with the 10 mm value recommended by ICRU. Contrary, for the space radiation environment the maximum dose equivalent was found at the surface of the sphere. This suggests that skin

  3. Techniques to maximize software reliability in radiation fields

    International Nuclear Information System (INIS)

    Eichhorn, G.; Piercey, R.B.

    1986-01-01

    Microprocessor system failures due to memory corruption by single event upsets (SEUs) and/or latch-up in RAM or ROM memory are common in environments where there is high radiation flux. Traditional methods to harden microcomputer systems against SEUs and memory latch-up have usually involved expensive large scale hardware redundancy. Such systems offer higher reliability, but they tend to be more complex and non-standard. At the Space Astronomy Laboratory the authors have developed general programming techniques for producing software which is resistant to such memory failures. These techniques, which may be applied to standard off-the-shelf hardware, as well as custom designs, include an implementation of Maximally Redundant Software (MRS) model, error detection algorithms and memory verification and management

  4. Personal Radiation Detector Field Test and Evaluation Campaign

    International Nuclear Information System (INIS)

    Chris A. Hodge, Ding Yuan, Raymond P. Keegan, Michael A. Krstich

    2007-01-01

    Following the success of the Anole test of portable detection system, the U.S. Department of Homeland Security (DHS) Domestic Nuclear Detection Office organized a test and evaluation campaign for personal radiation detectors (PRDs), also known as 'Pagers'. This test, 'Bobcat', was conducted from July 17 to August 8, 2006, at the Nevada Test Site. The Bobcat test was designed to evaluate the performance of PRDs under various operational scenarios, such as pedestrian surveying, mobile surveying, cargo container screening, and pedestrian chokepoint monitoring. Under these testing scenarios, many operational characteristics of the PRDs, such as gamma and neutron sensitivities, positive detection and false alarm rates, response delay times, minimum detectable activities, and source localization errors, were analyzed. This paper will present the design, execution, and methodologies used to test this equipment for the DHS

  5. Analyzing Damping Vibration Methods of Large-Size Space Vehicles in the Earth's Magnetic Field

    Directory of Open Access Journals (Sweden)

    G. A. Shcheglov

    2016-01-01

    Full Text Available It is known that most of today's space vehicles comprise large antennas, which are bracket-attached to the vehicle body. Dimensions of reflector antennas may be of 30 ... 50 m. The weight of such constructions can reach approximately 200 kg.Since the antenna dimensions are significantly larger than the size of the vehicle body and the points to attach the brackets to the space vehicles have a low stiffness, conventional dampers may be inefficient. The paper proposes to consider the damping antenna in terms of its interaction with the Earth's magnetic field.A simple dynamic model of the space vehicle equipped with a large-size structure is built. The space vehicle is a parallelepiped to which the antenna is attached through a beam.To solve the model problems, was used a simplified model of Earth's magnetic field: uniform, with intensity lines parallel to each other and perpendicular to the plane of the antenna.The paper considers two layouts of coils with respect to the antenna, namely: a vertical one in which an axis of magnetic dipole is perpendicular to the antenna plane, and a horizontal layout in which an axis of magnetic dipole lies in the antenna plane. It also explores two ways for magnetic damping of oscillations: through the controlled current that is supplied from the power supply system of the space vehicle, and by the self-induction current in the coil. Thus, four objectives were formulated.In each task was formulated an oscillation equation. Then a ratio of oscillation amplitudes and their decay time were estimated. It was found that each task requires the certain parameters either of the antenna itself, its dimensions and moment of inertia, or of the coil and, respectively, the current, which is supplied from the space vehicle. In each task for these parameters were found the ranges, which allow us to tell of efficient damping vibrations.The conclusion can be drawn based on the analysis of tasks that a specialized control system

  6. Electromagnetic signatures of far-field gravitational radiation in the 1 + 3 approach

    International Nuclear Information System (INIS)

    Chua, Alvin J K; Cañizares, Priscilla; Gair, Jonathan R

    2015-01-01

    Gravitational waves (GWs) from astrophysical sources can interact with background electromagnetic fields, giving rise to distinctive and potentially detectable electromagnetic signatures. In this paper, we study such interactions for far-field gravitational radiation using the 1 + 3 approach to relativity. Linearized equations for the electromagnetic field on perturbed Minkowski space are derived and solved analytically. The inverse Gertsenshteĭn conversion of GWs in a static electromagnetic field is rederived, and the resultant electromagnetic radiation is shown to be significant for highly magnetized pulsars in compact binary systems. We also obtain a variety of nonlinear interference effects for interacting gravitational and electromagnetic waves, although wave–wave resonances previously described in the literature are absent when the electric–magnetic self-interaction is taken into account. The fluctuation and amplification of electromagnetic energy flux as the GW strength increases towards the gravitational–electromagnetic frequency ratio is a possible signature of gravitational radiation from extended astrophysical sources. (paper)

  7. Different ways to organize the processes of financial administration : a field study of medium-sized Finnish companies

    OpenAIRE

    Nummela, Maria

    2011-01-01

    This research concentrates on exploring the ways how financial administration is currently organized in medium-sized companies in Finland. Decentralization, centralization and outsourcing are options that are available to different-sized companies. The study was executed as a field study in seven medium-sized Finnish companies that represent different branches. Furthermore, the research method was qualitative theme interview. As large companies have already established their financial service...

  8. Ballistic-type field penetration into metals illustrated by high- and low-frequency size-effect measurements in silver

    DEFF Research Database (Denmark)

    Gantmakher, V. F.; Lebech, Jens; Bak, Christen Kjeldahl

    1979-01-01

    Radio-frequency size-effect experiments were performed on silver plane-parallel plates at high, 45 GHz, and low, 3 MHz, frequencies. By investigation of size-effect structures we show the influence of frequency on the field distribution inside the metal. When the frequency increases, the splash...

  9. Ultra-fast bright field and fluorescence imaging of the dynamics of micrometer-sized objects

    Science.gov (United States)

    Chen, Xucai; Wang, Jianjun; Versluis, Michel; de Jong, Nico; Villanueva, Flordeliza S.

    2013-06-01

    High speed imaging has application in a wide area of industry and scientific research. In medical research, high speed imaging has the potential to reveal insight into mechanisms of action of various therapeutic interventions. Examples include ultrasound assisted thrombolysis, drug delivery, and gene therapy. Visual observation of the ultrasound, microbubble, and biological cell interaction may help the understanding of the dynamic behavior of microbubbles and may eventually lead to better design of such delivery systems. We present the development of a high speed bright field and fluorescence imaging system that incorporates external mechanical waves such as ultrasound. Through collaborative design and contract manufacturing, a high speed imaging system has been successfully developed at the University of Pittsburgh Medical Center. We named the system "UPMC Cam," to refer to the integrated imaging system that includes the multi-frame camera and its unique software control, the customized modular microscope, the customized laser delivery system, its auxiliary ultrasound generator, and the combined ultrasound and optical imaging chamber for in vitro and in vivo observations. This system is capable of imaging microscopic bright field and fluorescence movies at 25 × 106 frames per second for 128 frames, with a frame size of 920 × 616 pixels. Example images of microbubble under ultrasound are shown to demonstrate the potential application of the system.

  10. Prototyping a large field size IORT applicator for a mobile linear accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, Rogier W J; Dries, Wim J F [Catharina-Hospital Eindhoven, PO Box 1350, 5602 ZA, Eindhoven (Netherlands); Faddegon, Bruce A [University of California San Francisco Comprehensive Cancer Center, 1600 Divisadero Street, San Francisco, CA 94115-1708 (United States)], E-mail: rogier.janssen@mac.com

    2008-04-21

    The treatment of large tumors such as sarcomas with intra-operative radiotherapy using a Mobetron (registered) is often complicated because of the limited field size of the primary collimator and the available applicators (max Oe100 mm). To circumvent this limitation a prototype rectangular applicator of 80 x 150 mm{sup 2} was designed and built featuring an additional scattering foil located at the top of the applicator. Because of its proven accuracy in modeling linear accelerator components the design was based on the EGSnrc Monte Carlo simulation code BEAMnrc. First, the Mobetron (registered) treatment head was simulated both without an applicator and with a standard 100 mm applicator. Next, this model was used to design an applicator foil consisting of a rectangular Al base plate covering the whole beam and a pyramid of four stacked cylindrical slabs of different diameters centered on top of it. This foil was mounted on top of a plain rectangular Al tube. A prototype was built and tested with diode dosimetry in a water tank. Here, the prototype showed clinically acceptable 80 x 150 mm{sup 2} dose distributions for 4 MeV, 6 MeV and 9 MeV, obviating the use of complicated multiple irradiations with abutting field techniques. In addition, the measurements agreed well with the MC simulations, typically within 2%/1 mm.

  11. Prototyping a large field size IORT applicator for a mobile linear accelerator

    International Nuclear Information System (INIS)

    Janssen, Rogier W J; Dries, Wim J F; Faddegon, Bruce A

    2008-01-01

    The treatment of large tumors such as sarcomas with intra-operative radiotherapy using a Mobetron (registered) is often complicated because of the limited field size of the primary collimator and the available applicators (max Oe100 mm). To circumvent this limitation a prototype rectangular applicator of 80 x 150 mm 2 was designed and built featuring an additional scattering foil located at the top of the applicator. Because of its proven accuracy in modeling linear accelerator components the design was based on the EGSnrc Monte Carlo simulation code BEAMnrc. First, the Mobetron (registered) treatment head was simulated both without an applicator and with a standard 100 mm applicator. Next, this model was used to design an applicator foil consisting of a rectangular Al base plate covering the whole beam and a pyramid of four stacked cylindrical slabs of different diameters centered on top of it. This foil was mounted on top of a plain rectangular Al tube. A prototype was built and tested with diode dosimetry in a water tank. Here, the prototype showed clinically acceptable 80 x 150 mm 2 dose distributions for 4 MeV, 6 MeV and 9 MeV, obviating the use of complicated multiple irradiations with abutting field techniques. In addition, the measurements agreed well with the MC simulations, typically within 2%/1 mm

  12. Standardization of reference radiation field of beta for 85Kr using extrapolation chamber

    International Nuclear Information System (INIS)

    Nazaroh; Fendinugroho

    2013-01-01

    Standardization of reference radiation field of beta for 85 Kr in PTKMR-BATAN Laboratory has been performed at the SDD's 30 cm by using extrapolation chamber detector, coupled with Uni dose electrometer. The result was : (8.98±3 %) mGy/h, at 95 % confidence level. The aim of standardization of reference radiation field is to support radiation protection and safety program, provided by the International Atomic Energy Agency to its Member States, included BATAN-Indonesia, especially, PTKMR. The aim of radiation protection program and safety program is to promote an internationally harmonized approach for radiation measurement in protection level, besides for calibration of radiation measuring instrument, which users spread across Indonesia, with the number of about 795 firms in the year of 2012. These benefits can be felt by workers, communities and the environment, because by calibration, measurement survey meter, pocket dosimeter and TLD to be more accurate so that the radiation dose received by radiation workers is accurate and can be ascertained in a specified period, not to exceed a predetermined NBD by BAPETEN. The aim of this calibration is appropriate with the primary objective of calibration on IAEA/TRS16:2000. (author)

  13. Micro Penning Trap for Continuous Magnetic Field Monitoring in High Radiation Environments

    Science.gov (United States)

    Latorre, Javiera; Bollen, Georg; Gulyuz, Kerim; Ringle, Ryan; Bado, Philippe; Dugan, Mark; Lebit Team; Translume Collaboration

    2016-09-01

    As new facilities for rare isotope beams, like FRIB at MSU, are constructed, there is a need for new instrumentation to monitor magnetic fields in beam magnets that can withstand the higher radiation level. Currently NMR probes, the instruments used extensively to monitor magnetic fields, do not have a long lifespans in radiation-high environments. Therefore, a radiation-hard replacement is needed. We propose to use Penning trap mass spectrometry techniques to make high precision magnetic field measurements. Our Penning microtrap will be radiation resistant as all of the vital electronics will be at a safe distance from the radiation. The trap itself is made from materials not subject to radiation damage. Penning trap mass spectrometers can determine the magnetic field by measuring the cyclotron frequency of an ion with a known mass and charge. This principle is used on the Low Energy Beam Ion Trap (LEBIT) minitrap at NSCL which is the foundation for the microtrap. We have partnered with Translume, who specialize in glass micro-fabrication, to develop a microtrap in fused-silica glass. A microtrap is finished and ready for testing at NSCL with all of the electronic and hardware components setup. DOE Phase II SBIR Award No. DE-SC0011313, NSF Award Number 1062410 REU in Physics, NSF under Grant No. PHY-1102511.

  14. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives

    Energy Technology Data Exchange (ETDEWEB)

    Contado, Catia, E-mail: Catia.Contado@unife.it [University of Ferrara, Department of Chemical and Pharmaceutical Sciences, via L. Borsari, 46, 44121 Ferrara (Italy); Ravani, Laura [University of Ferrara, Department of Life Sciences and Biotechnologies, via L. Borsari, 46, 44121 Ferrara (Italy); Passarella, Martina [University of Ferrara, Department of Chemical and Pharmaceutical Sciences, via L. Borsari, 46, 44121 Ferrara (Italy)

    2013-07-25

    Graphical abstract: -- Highlights: •Four types of SiO{sub 2} particles were characterized by SdFFF, PCS and EM techniques. •Clusters of 10 nm nanoparticles were found in some SiO{sub 2} samples. •A method was set up to extract SiO{sub 2} particles from food matrices. •The effects of the carrier solution composition on SdFFF separations were evaluated. •Particle size distributions were obtained from SiO{sub 2} particles extracted from foodstuffs. -- Abstract: Four types of SiO{sub 2}, available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w{sup −1}) a nearly silica-free instant barley coffee powder with a known SiO{sub 2} sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO{sub 2} particles and verify the new particle size distribution. The SiO{sub 2} content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w{sup −1}). The protocol to isolate the silica particles was so applied to the most SiO{sub 2}-rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification.

  15. BWR Radiation Assessment and Control Program: assessment and control of BWR radiation fields. Volume 1. Executive summary

    International Nuclear Information System (INIS)

    Anstine, L.D.

    1983-05-01

    This report covers work on the BWR Radiation Assessment and Control (BRAC) Program from 1978 to 1982. The major activities during this report period were assessment of the radiation-level trends in BWRs, evaluation of the effects of forward-pumped heater drains on BWR water quality, installation and operation of a corrosion-product deposition loop in an operating BWR, and analyzation of fuel-deposit samples from two BWRs. Radiation fields were found to be controlled by cobalt-60 and to vary from as low as 50 mr/hr to as high as 800 mr/hr on the recirculation-system piping. Detailed information on BWR corrosion films and system deposits is presented in the report. Additionally, the results of an oxygen-injection experiment and recontamination monitoring studies are provided

  16. SEL Hardness Assurance in a Mixed Radiation Field

    CERN Document Server

    Garcia Alia, Ruben; Danzeca, Salvatore; Ferlet-Cavrois, Veronique; Frost, Christopher; Gaillard, Remi; Mekki, Julien; Saigné, Frédéric; Thornton, Adam; Uznanski, Slawosz; Worbel, Frédéric; CERN. Geneva. ATS Department

    2015-01-01

    This paper explores the relationship between monoenergetic and mixed-field Single Event Latchup (SEL) cross sections, concluding for components with a very strong energy dependence and highly-energetic environments, test results from monoenergetic or soft mixed-field spectra can significantly underestimate the operational failure rate. We introduce a semi-empirical approach that can be used to evaluate the SEL rate for such environments based on monoenergetic measurements and information or assumptions on the respective sensitive volume and materials surrounding it. We show that the presence of high-Z materials such as tungsten is particularly important in determining the hadron cross section energy dependence for components with relatively large LET thresholds.

  17. Modern Radiation Therapy for Hodgkin Lymphoma: Field and Dose Guidelines From the International Lymphoma Radiation Oncology Group (ILROG)

    International Nuclear Information System (INIS)

    Specht, Lena; Yahalom, Joachim; Illidge, Tim; Berthelsen, Anne Kiil; Constine, Louis S.; Eich, Hans Theodor; Girinsky, Theodore; Hoppe, Richard T.; Mauch, Peter; Mikhaeel, N. George; Ng, Andrea

    2014-01-01

    Radiation therapy (RT) is the most effective single modality for local control of Hodgkin lymphoma (HL) and an important component of therapy for many patients. These guidelines have been developed to address the use of RT in HL in the modern era of combined modality treatment. The role of reduced volumes and doses is addressed, integrating modern imaging with 3-dimensional (3D) planning and advanced techniques of treatment delivery. The previously applied extended field (EF) and original involved field (IF) techniques, which treated larger volumes based on nodal stations, have now been replaced by the use of limited volumes, based solely on detectable nodal (and extranodal extension) involvement at presentation, using contrast-enhanced computed tomography, positron emission tomography/computed tomography, magnetic resonance imaging, or a combination of these techniques. The International Commission on Radiation Units and Measurements concepts of gross tumor volume, clinical target volume, internal target volume, and planning target volume are used for defining the targeted volumes. Newer treatment techniques, including intensity modulated radiation therapy, breath-hold, image guided radiation therapy, and 4-dimensional imaging, should be implemented when their use is expected to decrease significantly the risk for normal tissue damage while still achieving the primary goal of local tumor control. The highly conformal involved node radiation therapy (INRT), recently introduced for patients for whom optimal imaging is available, is explained. A new concept, involved site radiation therapy (ISRT), is introduced as the standard conformal therapy for the scenario, commonly encountered, wherein optimal imaging is not available. There is increasing evidence that RT doses used in the past are higher than necessary for disease control in this era of combined modality therapy. The use of INRT and of lower doses in early-stage HL is supported by available data. Although the

  18. Individual monitoring in high-energy stray radiation fields

    International Nuclear Information System (INIS)

    Hoefert, M.; Stevenson, G.R.

    1995-01-01

    Due to the lack of passive or active devices that could be considered as personal dosemeters in high-energy stray fields one can at present only perform individual monitoring around high energy accelerators. Of all detectors currently available it is shown that the NTA film is the most suitable method for individually monitoring the neutron exposure of more than 3000 persons regularly, reliably, and cost effectively like at CERN. (author)

  19. Radiation-reaction electromagnetic fields in metasurfaces, a complete description of their optical properties

    OpenAIRE

    Merano, Michele

    2018-01-01

    This paper derives the macroscopic electric and magnetic fields and the surface susceptibilities for a metasurface, starting from the microscopic scatterer distribution. It is assumed that these scatterers behave as electric and magnetic dipoles under the influence of the incident radiation. Interestingly not only the retarded electromagnetic fields from oscillating dipoles are relevant to pass from the microscopic to the macroscopic representation, but the advanced fields must be considered ...

  20. Characterisation of micro-sized and nano-sized tungsten oxide-epoxy composites for radiation shielding of diagnostic X-rays.

    Science.gov (United States)

    Azman, N Z Noor; Siddiqui, S A; Low, I M

    2013-12-01

    Characteristics of X-ray transmissions were investigated for epoxy composites filled with 2-10 vol% WO3 loadings using synchrotron X-ray absorption spectroscopy (XAS) at 10-40 keV. The results obtained were used to determine the equivalent X-ray energies for the operating X-ray tube voltages of mammography and radiology machines. The results confirmed the superior attenuation ability of nano-sized WO3-epoxy composites in the energy range of 10-25 keV when compared to their micro-sized counterparts. However, at higher synchrotron radiation energies (i.e., 30-40 keV), the X-ray transmission characteristics were similar with no apparent size effect for both nano-sized and micro-sized WO3-epoxy composites. The equivalent X-ray energies for the operating X-ray tube voltages of the mammography unit (25-49 kV) were in the range of 15-25 keV. Similarly, for a radiology unit operating at 40-60 kV, the equivalent energy range was 25-40 keV, and for operating voltages greater than 60 kV (i.e., 70-100 kV), the equivalent energy was in excess of 40 keV. The mechanical properties of epoxy composites increased initially with an increase in the filler loading but a further increase in the WO3 loading resulted in deterioration of flexural strength, modulus and hardness. © 2013.

  1. Gamma radiation field extremity personal dosimeter. Calibration and implementation

    International Nuclear Information System (INIS)

    Papadopulos, S.B.; Gregori, B.N.; Cruzate, J.A.

    2000-01-01

    The purpose of this paper is to show the extremity dose equivalent-kerma conversion factors obtained theoretical and experimentally in arm and finger for normally incident gamma radiation. Extremity dosemeters, based on termoluminescent dosimeters (TLD) LiF 7 (TLD-700, Harshaw), have been irradiated on designed as finger and arm phantoms. The finger phantom is been characterised as a solid cylinder made of polymethylmethacrylate (PMMA) 19mm diameter and 300mm height. The arm phantom is a cylinder 73mm external diameter with PMMA walls 2.5mm thick filled with water and 300mm height. There were used several radiation sources like Co-60 and Cs-137 from the Regional Reference Dosimetry Centre (CRR) of the National Atomic Energy Commission (CNEA) and from the Nuclear Regulatory Authority (ARN) of Argentina. In the same way RX wide spectrum irradiations were made in the ISO-4037 qualities W60, W110 and W200. At the same time the conversion factors have been theoretically obtained. In order to achieve this, the finger and arm phantoms have been modelled and the photon and electron transport have been done with the Monte Carlo code MCNP-4B. There was a good agreement between the theoretical and experimental results, showing a difference less than 8%. Also the experimental results have been compared with the published data available giving a difference less than 7%. In this work is shown the performance of the extremity dosimeter usually used by the exposed workers of the ARN. It has got a similar energy response in the range of W110-Co-60 (not more than 7%) with respect to the experimental results obtained. The dose equivalent-kerma conversion factors are going to be used in the dose equivalent evaluation of workers mainly hands exposed. Related with the incident energy several applied recommendations have been made. An application is presented in nuclear medicine experiences. In the case of a thyroid treatment with 131 I, the external dose workers have been evaluated

  2. Size-appropriate radiation doses in pediatric body CT: a study of regional community adoption in the United States

    International Nuclear Information System (INIS)

    Hopkins, Katharine L.; Vajtai, Petra L.; Pettersson, David R.; Spinning, Kristopher; Beckett, Brooke R.; Koudelka, Caroline W.; Bardo, Dianna M.E.

    2013-01-01

    During the last decade, there has been a movement in the United States toward utilizing size-appropriate radiation doses for pediatric body CT, with smaller doses given to smaller patients. This study assesses community adoption of size-appropriate pediatric CT techniques. Size-specific dose estimates (SSDE) in pediatric body scans are compared between community facilities and a university children's hospital that tailors CT protocols to patient size as advocated by Image Gently. We compared 164 pediatric body scans done at community facilities (group X) with 466 children's hospital scans. Children's hospital scans were divided into two groups: A, 250 performed with established pediatric weight-based protocols and filtered back projection; B, 216 performed with addition of iterative reconstruction technique and a 60% reduction in volume CT dose index (CTDI vol ). SSDE was calculated and differences among groups were compared by regression analysis. Mean SSDE was 1.6 and 3.9 times higher in group X than in groups A and B and 2.5 times higher for group A than group B. A model adjusting for confounders confirmed significant differences between group pairs. Regional community hospitals and imaging centers have not universally adopted child-sized pediatric CT practices. More education and accountability may be necessary to achieve widespread implementation. Since even lower radiation doses are possible with iterative reconstruction technique than with filtered back projection alone, further exploration of the former is encouraged. (orig.)

  3. Size-appropriate radiation doses in pediatric body CT: a study of regional community adoption in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, Katharine L.; Vajtai, Petra L. [Oregon Health and Science University, Department of Diagnostic Radiology, DC7R, Portland, OR (United States); Oregon Health and Science University, Department of Pediatrics, Portland, OR (United States); Pettersson, David R.; Spinning, Kristopher; Beckett, Brooke R. [Oregon Health and Science University, Department of Diagnostic Radiology, DC7R, Portland, OR (United States); Koudelka, Caroline W. [Oregon Health and Science University, Division of Biostatistics, Department of Public Health and Preventive Medicine, Portland, OR (United States); Bardo, Dianna M.E. [Oregon Health and Science University, Department of Diagnostic Radiology, DC7R, Portland, OR (United States); Oregon Health and Science University, Department of Cardiovascular Medicine, Portland, OR (United States)

    2013-09-15

    During the last decade, there has been a movement in the United States toward utilizing size-appropriate radiation doses for pediatric body CT, with smaller doses given to smaller patients. This study assesses community adoption of size-appropriate pediatric CT techniques. Size-specific dose estimates (SSDE) in pediatric body scans are compared between community facilities and a university children's hospital that tailors CT protocols to patient size as advocated by Image Gently. We compared 164 pediatric body scans done at community facilities (group X) with 466 children's hospital scans. Children's hospital scans were divided into two groups: A, 250 performed with established pediatric weight-based protocols and filtered back projection; B, 216 performed with addition of iterative reconstruction technique and a 60% reduction in volume CT dose index (CTDI{sub vol}). SSDE was calculated and differences among groups were compared by regression analysis. Mean SSDE was 1.6 and 3.9 times higher in group X than in groups A and B and 2.5 times higher for group A than group B. A model adjusting for confounders confirmed significant differences between group pairs. Regional community hospitals and imaging centers have not universally adopted child-sized pediatric CT practices. More education and accountability may be necessary to achieve widespread implementation. Since even lower radiation doses are possible with iterative reconstruction technique than with filtered back projection alone, further exploration of the former is encouraged. (orig.)

  4. Magnetic field dependence of microwave radiation in intermediate-length Josephson junctions

    DEFF Research Database (Denmark)

    Sørensen, Mads Peter; Parmentier, R. D.; Christiansen, Peter Leth

    1984-01-01

    furnish the current and field dependence of the oscillation configuration, from which can be calculated average voltages, frequencies, and power spectra. Simulation and experimental results are in good agreement with regard to the lobe structure of the height of the first zero-field step and/or second...... Fiske step in magnetic field and the field dependence of the radiation frequency within the various lobes, including details such as hysteresis between lobes. The simulations predict an alternation of the dominant frequency component with increasing field that accounts well for the experimental...

  5. Study of the accuracy of radiation field calculations in media

    International Nuclear Information System (INIS)

    Bolyatko, V.V.; Vyrskij, M.Yu.; Ilyushkin, A.I.; Mashkovich, V.P.; Sakharov, V.K.; Stroganov, A.A.

    1981-01-01

    The sensitivity p of the radiation transport calculations to variations of input parameters Xsub(i) is theoretically analyzed, and the calculational errors induced by uncertainties of initial data are evaluated. Two calculational methods are considered: the direct substitution method using the ROZ-5 code and method using the linear perturbation theory. In order to calculate p(Xsub(i)) and bilinear convolutions of the conjugated transport equations the ZAKAT code has been developed. The calculations use the ZAKAT, ROZ-11 and APAMAKO-2F codes. As an example of practical use of the method proposed a shielding composition characteristic for fast reactors was analyzed. A plane monodirectional neutron beam of the BR-10 reactor falls onto a 5-layer stainless steel (1Kh18N10T)-carbon barrier. The sensitivily of the neutron dose absorbed in tissue to the cross sections of all the shielding constituents and to the source and detector representation functions has been calculated. A comparison of the calculations with experimental data proves the validity of the calculational method [ru

  6. Technical Note: Response measurement for select radiation detectors in magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, M., E-mail: michaelreynolds@ualberta.net [Department of Oncology, Medical Physics Division, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Fallone, B. G. [Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada and Departments of Oncology and Physics, University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada); Rathee, S. [Department of Medical Physics, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada and Department of Oncology, Medical Physics Division,University of Alberta, 11560 University Avenue, Edmonton, Alberta T6G 1Z2 (Canada)

    2015-06-15

    Purpose: Dose response to applied magnetic fields for ion chambers and solid state detectors has been investigated previously for the anticipated use in linear accelerator–magnetic resonance devices. In this investigation, the authors present the measured response of selected radiation detectors when the magnetic field is applied in the same direction as the radiation beam, i.e., a longitudinal magnetic field, to verify previous simulation only data. Methods: The dose response of a PR06C ion chamber, PTW60003 diamond detector, and IBA PFD diode detector is measured in a longitudinal magnetic field. The detectors are irradiated with buildup caps and their long axes either parallel or perpendicular to the incident photon beam. In each case, the magnetic field dose response is reported as the ratio of detector signals with to that without an applied longitudinal magnetic field. The magnetic field dose response for each unique orientation as a function of magnetic field strength was then compared to the previous simulation only studies. Results: The measured dose response of each detector in longitudinal magnetic fields shows no discernable response up to near 0.21 T. This result was expected and matches the previously published simulation only results, showing no appreciable dose response with magnetic field. Conclusions: Low field longitudinal magnetic fields have been shown to have little or no effect on the dose response of the detectors investigated and further lend credibility to previous simulation only studies.

  7. A NUMERICAL TREATMENT OF ANISOTROPIC RADIATION FIELDS COUPLED WITH RELATIVISTIC RESISTIVE MAGNETOFLUIDS

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroyuki R. [Center for Computational Astrophysics, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Ohsuga, Ken [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

    2013-08-01

    We develop a numerical scheme for solving fully special relativistic, resistive radiation magnetohydrodynamics. Our code guarantees conservation of total mass, momentum, and energy. The radiation energy density and the radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation field, in contrast to the Eddington approximation, as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly the Harten-Lax-van Leer scheme; the HLLC and HLLD schemes are also solved for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in an optically thick regime or a large magnetic Reynolds number regime. Although we need to invert 4 Multiplication-Sign 4 matrices (for the gas-radiation interaction) and 3 Multiplication-Sign 3 matrices (for the magnetic energy dissipation) at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek-type magnetic reconnection, revealing the reduction of the reconnection rate via radiation drag.

  8. A NUMERICAL TREATMENT OF ANISOTROPIC RADIATION FIELDS COUPLED WITH RELATIVISTIC RESISTIVE MAGNETOFLUIDS

    International Nuclear Information System (INIS)

    Takahashi, Hiroyuki R.; Ohsuga, Ken

    2013-01-01

    We develop a numerical scheme for solving fully special relativistic, resistive radiation magnetohydrodynamics. Our code guarantees conservation of total mass, momentum, and energy. The radiation energy density and the radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation field, in contrast to the Eddington approximation, as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly the Harten-Lax-van Leer scheme; the HLLC and HLLD schemes are also solved for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in an optically thick regime or a large magnetic Reynolds number regime. Although we need to invert 4 × 4 matrices (for the gas-radiation interaction) and 3 × 3 matrices (for the magnetic energy dissipation) at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek-type magnetic reconnection, revealing the reduction of the reconnection rate via radiation drag

  9. Modern Radiation Therapy for Extranodal Lymphomas: Field and Dose Guidelines From the International Lymphoma Radiation Oncology Group

    Energy Technology Data Exchange (ETDEWEB)

    Yahalom, Joachim, E-mail: yahalomj@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Illidge, Tim [Institute of Cancer Sciences, University of Manchester, Manchester Academic Health Sciences Centre, The Christie National Health Service Foundation Trust, Manchester (United Kingdom); Specht, Lena [Department of Oncology and Hematology, Rigshospitalet, University of Copenhagen, Copenhagen (Denmark); Hoppe, Richard T. [Department of Radiation Oncology, Stanford University, Palo Alto, California (United States); Li, Ye-Xiong [Department of Radiation Oncology, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China); Tsang, Richard [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario (Canada); Wirth, Andrew [Division of Radiation Oncology, Peter MacCallum Cancer Institute, St. Andrews Place, East Melbourne (Australia)

    2015-05-01

    Extranodal lymphomas (ENLs) comprise about a third of all non-Hodgkin lymphomas (NHL). Radiation therapy (RT) is frequently used as either primary therapy (particularly for indolent ENL), consolidation after systemic therapy, salvage treatment, or palliation. The wide range of presentations of ENL, involving any organ in the body and the spectrum of histological sub-types, poses a challenge both for routine clinical care and for the conduct of prospective and retrospective studies. This has led to uncertainty and lack of consistency in RT approaches between centers and clinicians. Thus far there is a lack of guidelines for the use of RT in the management of ENL. This report presents an effort by the International Lymphoma Radiation Oncology Group (ILROG) to harmonize and standardize the principles of treatment of ENL, and to address the technical challenges of simulation, volume definition and treatment planning for the most frequently involved organs. Specifically, detailed recommendations for RT volumes are provided. We have applied the same modern principles of involved site radiation therapy as previously developed and published as guidelines for Hodgkin lymphoma and nodal NHL. We have adopted RT volume definitions based on the International Commission on Radiation Units and Measurements (ICRU), as has been widely adopted by the field of radiation oncology for solid tumors. Organ-specific recommendations take into account histological subtype, anatomy, the treatment intent, and other treatment modalities that may be have been used before RT.

  10. Modern Radiation Therapy for Extranodal Lymphomas: Field and Dose Guidelines From the International Lymphoma Radiation Oncology Group

    International Nuclear Information System (INIS)

    Yahalom, Joachim; Illidge, Tim; Specht, Lena; Hoppe, Richard T.; Li, Ye-Xiong; Tsang, Richard; Wirth, Andrew

    2015-01-01

    Extranodal lymphomas (ENLs) comprise about a third of all non-Hodgkin lymphomas (NHL). Radiation therapy (RT) is frequently used as either primary therapy (particularly for indolent ENL), consolidation after systemic therapy, salvage treatment, or palliation. The wide range of presentations of ENL, involving any organ in the body and the spectrum of histological sub-types, poses a challenge both for routine clinical care and for the conduct of prospective and retrospective studies. This has led to uncertainty and lack of consistency in RT approaches between centers and clinicians. Thus far there is a lack of guidelines for the use of RT in the management of ENL. This report presents an effort by the International Lymphoma Radiation Oncology Group (ILROG) to harmonize and standardize the principles of treatment of ENL, and to address the technical challenges of simulation, volume definition and treatment planning for the most frequently involved organs. Specifically, detailed recommendations for RT volumes are provided. We have applied the same modern principles of involved site radiation therapy as previously developed and published as guidelines for Hodgkin lymphoma and nodal NHL. We have adopted RT volume definitions based on the International Commission on Radiation Units and Measurements (ICRU), as has been widely adopted by the field of radiation oncology for solid tumors. Organ-specific recommendations take into account histological subtype, anatomy, the treatment intent, and other treatment modalities that may be have been used before RT

  11. The effect of mitotic inhibitors on DNA strand size and radiation-associated break repair in Down syndrome fibroblasts

    International Nuclear Information System (INIS)

    Woods, W.G.; Steiner, M.E.; Kalvonjian, S.L.

    1985-01-01

    The effect of mitotic inhibitors on formation and repair of DNA breaks was studied in cultured fibroblasts from patients with Down syndrome in order to investigate the hypothesis that the karyotyping procedure itself may play a role in the increased chromosome breakage seen in these cells after gamma radiation exposure. Using the nondenaturing elution and alkaline elution techniques to examine fibroblasts from Down syndrome patients and from controls, no specific abnormalities in Down syndrome cells could be detected after exposure to mitotic inhibitors, including rate and extent of elution of DNA from filters as well as repair of radiation-induced DNA breaks. In both normal and Down syndrome cell strains, however, exposure to mitotic inhibitors was associated with a decrease in cellular DNA strand size, suggesting the presence of drug-induced DNA strand breaks. The mechanism of increased chromosome sensitivity of Down syndrome cells to gamma radiation remains unknown. (orig.)

  12. Development and testing of a thermoluminescent dosemeter for mixed neutron-photon-beta radiation fields

    International Nuclear Information System (INIS)

    Zummo, J.J.; Liu, J.C.

    1998-08-01

    A new four-element thermoluminescent (TL) dosemeter and dose evaluation algorithm have been developed and tested to better characterize personnel exposure in mixed neutron-photon-beta radiation fields. The prototype dosemeter is based on a commercially available TL card (with three LiF-7 chips and one LiF-6 chip) and modified filtration elements. The new algorithm takes advantage of the high temperature peak characteristics of the LiF-6 element to better quantify the neutron dose component. The dosemeter was tested in various radiation fields, consisting of mixtures of two radiation types typically used for dosemeter performance testing, as well as mixtures of three radiation types to simulate possible exposure conditions. The new dosemeter gave superior performance, based on the tolerance levels, when using the new algorithm as compared to a conventional algorithm that did not use the high temperature peak methodology. The limitations and further improvements are discussed

  13. Intensity of low-frequency radiations and the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Larkina, V.I.; Likhter, Ya.I.

    1983-01-01

    The data of measurements of ELF/VLF radiations at ''Interkosmos-13'' artificial Earth satellite in auroral latitudes and in the polar cap in the vernal equinox of 1975 are compared with characteristics of interplanetary magnetic field (IMF). The absence of north-south asymmetry of variations of ELF/VLF-radiation Intensity in the outer ionosphere versus the IMF characteristics is noted. The intensity of natural ELF- and VLF-radiations depends in a complex way on parameters of the magnetospheric plasma: composition and concentration of ''cold'' particles, geomagnetic field intensity, properties of energetic particle fluxes. The considered variations in the radiation amplitude versus the IMF characteristics show the predominant role of the sector structure polarity and IMF Bsub(y) component sign

  14. Standardization of radiation protection measurements in mixed fields of an extended energy range

    International Nuclear Information System (INIS)

    Hoefert, M.; Stevenson, G.R.

    1977-01-01

    The improved ICRU concept of dose equivalent index aims at standardizing both area and personnel dose measurements so that the results on the dosimetry of external irradiations in radiation protection become compatible. It seems that for photon and neutron energies up to 3 and 20 MeV respectively the realization of dose-equivalent index is straightforward, but the inclusion of higher energies and/or other types of radiation will lead both to conceptual and practical difficulties. It will be shown that practical measurements in mixed radiation fields of an extended energy range for protection purposes will overestimate the standardized quantity. While area measurements can be performed to represent a good approximation, greater uncertainties have to be accepted in personnel dosimetry for stray radiation fields around GeV proton accelerators

  15. Experiences in Accreditation of Laboratories in the Field of Radiation Science

    International Nuclear Information System (INIS)

    Franic, Z.; Galjanic, S.; Krizanec, D.

    2011-01-01

    Efficient interaction of technical legislation, metrology, standardization and accreditation within the system of quality infrastructure is precondition for assurance of safety of goods and services as well as protection of humans and environment. In the paper importance of quality infrastructure on national and international levels is presented while special interest is paid to accreditation. Current situation regarding the accreditation of laboratories in the field of radiation science is presented. Regarding this field, in Croatia three laboratories are accredited by Croatian Accreditation Agency: 1. Laboratory for Radioecology, Rudjer Boskovic Institute (Scope: Measurement of radionuclide content in environmental samples and commodities - Including foodstuffs and drinking water) 2. EKOTEH Dozimetrija Ltd., Department for Radiation Protection (Scope: Testing in the scope of ionizing and nonionizing radiation) 3. Radiation Protection Unit, Institute for Medical Research and Occupational Health (Scope: Determination of radioactivity). (author)

  16. Pulsed mixed n, γ radiation fields for electronic testing

    International Nuclear Information System (INIS)

    Nurdin, G.; Becret, C.; Jaureguy, J.C.; Vie, M.; Baboulet, J.P.; Lapeyre, P.; Ramisse, D.

    1994-01-01

    For combined n, γ TREE testing we have modified the CALIBAN Fast Burst Reactor Field with CdO/Epoxy converters to cover the range [10 11 -10 12 ] n.cm -2 (1 MeV Si), [10 7 - 10 8 ] cGy(Si).s -1 . Activation and fission σ φvector, 1 MeV(Si) fluences, neutron spectra, total exposures and dose rates were predicted with good agreement by n, γ photon transport codes. (author). 12 refs., 2 figs., 1 tab

  17. Droplet size characteristics and energy input requirements of emulsions formed using high-intensity-pulsed electric fields

    International Nuclear Information System (INIS)

    Scott, T.C.; Sisson, W.G.

    1987-01-01

    Experimental methods have been developed to measure droplet size characteristics and energy inputs associated with the rupture of aqueous droplets by high-intensity-pulsed electric fields. The combination of in situ microscope optics and high-speed video cameras allows reliable observation of liquid droplets down to 0.5 μm in size. Videotapes of electric-field-created emulsions reveal that average droplet sizes of less than 5 μm are easily obtained in such systems. Analysis of the energy inputs into the fluids indicates that the electric field method requires less than 1% of the energy required from mechanical agitation to create comparable droplet sizes. 11 refs., 3 figs., 2 tabs

  18. Electron beam extraction system with a ring radiation field

    International Nuclear Information System (INIS)

    Auslender, V.L.; Kuksanov, N.K.; Polyakov, V.A.; Salimov, R.A.; Chertok, I.L.

    1979-01-01

    Description and results of testings of two electron beam extraction systems for shaping of a circular irradiation field are given. One of the systems contains three 20 cm long outlet windows arranged at 120 deg angle with respect to each other. Tests at the ILU-6 accelerator have shown that the given system provides 150 mm zone irradiation from three sides. Beam utilization factor when irradiating three 40 mm dia tubes amounted to 35% which provides capacity of 2.5 txMrad/h at 20 kW beam power. The other extraction system includes two C-form magnets producing nonuniform and opposing magnetic fields. This system tests at the EhLV-2 accelerator have shown that at 0.8-1.5 MeV electron energy it is possible to irradiate of 60 and 100 mm dia objects, accordingly. The system may be used together with both constant-action and pulse-action accelerators having extraction with linear scanning [ru

  19. Experimental determination of radiated internal wave power without pressure field data

    OpenAIRE

    Lee, Frank M.; Paoletti, M. S.; Swinney, Harry L.; Morrison, P. J.

    2014-01-01

    We present a method to determine, using only velocity field data, the time-averaged energy flux $\\left$ and total radiated power $P$ for two-dimensional internal gravity waves. Both $\\left$ and $P$ are determined from expressions involving only a scalar function, the stream function $\\psi$. We test the method using data from a direct numerical simulation for tidal flow of a stratified fluid past a knife edge. The results for the radiated internal wave power given by the stream function method...

  20. Plasma wave instability and amplification of terahertz radiation in field-effect-transistor arrays

    International Nuclear Information System (INIS)

    Popov, V V; Tsymbalov, G M; Shur, M S

    2008-01-01

    We show that the strong amplification of terahertz radiation takes place in an array of field-effect transistors at small DC drain currents due to hydrodynamic plasmon instability of the collective plasmon mode. Planar designs compatible with standard integrated circuit fabrication processes and strong coupling of terahertz radiation to plasmon modes in FET arrays make such arrays very attractive for potential applications in solid-state terahertz amplifiers and emitters

  1. Collective migration of adsorbed atoms on a solid surface in the laser radiation field

    International Nuclear Information System (INIS)

    Andreev, V V; Ignat'ev, D V; Telegin, Gennadii G

    2004-01-01

    The lateral (in the substrate plane) interaction between dipoles induced in particles adsorbed on a solid surface is studied in a comparatively weak laser radiation field with a Gaussian transverse distribution. It is shown that the particles migrate over the surface in the radial direction either outside an illuminated spot with the formation of a 'crater' or inside the spot with the formation of a 'mound'. (interaction of laser radiation with matter. laser plasma)

  2. New three-dimensional moving field radiation therapy for brain tumors

    Energy Technology Data Exchange (ETDEWEB)

    Mitsuyama, Fuyuki; Kanno, Tetsuo; Nagata, Yutaka; Koga, Sukehiko [Fujita-Gakuen Health Univ., Toyoake, Aichi (Japan); Jain, V K

    1992-06-01

    A new modified rotation radiation method called 'three-dimensional moving field radiation therapy' is described. The new method uses rotation in many planes while maintaining the same isocenter to achieve a good spatial dose distribution. This delivers a high dose to tumors and spares the surrounding normal structures. This easy method can be carried out using the equipment for conventional rotation radiation therapy. The new method was superior to the one plane rotation radiation therapy using a physical phantom with film, a chemical phantom using the iodine-starch reaction, and a new biological model using tumor cells. Treatment of six brain tumors irradiated with total air doses of 50-60 Gy caused no hair loss or radiation necrosis. (author).

  3. The influence of continuum radiation fields on hydrogen radio recombination lines

    Science.gov (United States)

    Prozesky, Andri; Smits, Derck P.

    2018-05-01

    Calculations of hydrogen departure coefficients using a model with the angular momentum quantum levels resolved that includes the effects of external radiation fields are presented. The stimulating processes are important at radio frequencies and can influence level populations. New numerical techniques with a solid mathematical basis have been incorporated into the model to ensure convergence of the solution. Our results differ from previous results by up to 20 per cent. A direct solver with a similar accuracy but more efficient than the iterative method is used to evaluate the influence of continuum radiation on the hydrogen population structure. The effects on departure coefficients of continuum radiation from dust, the cosmic microwave background, the stellar ionising radiation, and free-free radiation are quantified. Tables of emission and absorption coefficients for interpreting observed radio recombination lines are provided.

  4. Characterization of CERN-EU high energy reference radiation fields with recombination chamber

    International Nuclear Information System (INIS)

    Golnik, N.

    1998-01-01

    The CERN-EU reference radiation field facility (called CERFF) is available behind a shielding of high-energy particles beam at CERN since 1993. At present the parameters of the radiation from beam target are well investigated, however, there are still some serious doubts concerning contribution of low-LET concurrent radiation. This paper presents an experimental procedure for determination of the contribution from the concurrent radiation by measuring the absorbed dose and recombination index of radiation quality at different beam intensities. Additionally, the values of H * (10) were measured in several measuring locations. Measurements were performed with a REM-2 recombination chamber and compared with those obtained by using a HANDI-TEPC instrument. (author)

  5. A method for radiobiological investigations in radiation fields with different LET and high dose rates

    International Nuclear Information System (INIS)

    Grundler, W.

    1976-01-01

    For investigations: 1. Performed in the field of radiobiology with different LET-radiation and a relatively high background dose rate of one component (e.g. investigations with fast and intermediate reactor neutrons) 2. Concerning radiation risk studies within a wide range 3. Of irradiations, covering a long time period (up to 100 days) a test system is necessary which on the one hand makes it possible to analyze the influence of different LET radiation and secondly shows a relative radiation resistant behaviour and allows a simple cell cycle regulation. A survey is given upon the installed device of a simple cell observation method, the biological test system used and the analysis of effects caused by dose, repair and LET. It is possible to analyze the behaviour of the nonsurvival cells and to demonstrate different reactions of the test parameters to the radiation of different LET. (author)

  6. Special radiation protection aspects of radiotherapy and nuclear medicine in a medium-sized Swiss hospital

    International Nuclear Information System (INIS)

    Benes, I.; Heinzel, F.; Mueller-Duysing, W.

    1985-01-01

    The evolution of radiation protection in Switzerland caused the Triemli City Hospital to implement building modifications throughout its 13 years of existence which have not been completed todate. However, modest methods allowed to find practicable solutions which largely comply with today's radiation protection regulation. Radiation protection provisions have been rendered more stringent thus resulting in more jobs. At least one additional staff member is required in order to discharge all supervisory functions required like incorporation controls, controls of cleaning and technical staff for their working correctly, contamination controls of floors and working areas, exit controls of special working clothes, etc. The best solution for the hospital would be to have one health physics man specifically commissioned with and employed for radiation protection. (orig./HSCH) [de

  7. Influence of high-dose gamma radiation and particle size on antioxidant properties of Maize ( Zea mays L.) flour

    International Nuclear Information System (INIS)

    Nawaz, Haq; Shad, Muhammad Aslam; Rehman, Tanzila; Ramzan, Ayesha

    2016-01-01

    Influence of high-dose gamma radiation and particle size on antioxidant properties of maize (Zea mays L.) flour was studied using response surface methodology. A central composite design based on three levels of each of particle size, in terms of mesh number (40, 60 and 80 meshes), and gamma radiation dose (25, 50 and 75 kGy) was constructed. A statistically significant dose-dependent decrease (p<0.05) in antioxidant properties of gamma irradiated flour was observed. However, an increase in the mesh number (decrease in particle size of flour) resulted in an increase in antioxidant properties. The optimum level of radiation dose to achieve maximum value of responses was found to be 50 kGy for Trolox equivalent total antioxidant activity (TETAOA), 25 kGy for iron chelating ability (ICA), 25 kGy for reducing power (RP) and 75 kGy for linoleic acid reduction capacity (LARC). However, the optimum level of mesh number to achieve desired levels of TETAOA, ICA, RP and LARC was found to be 80 meshes. (author)

  8. Influence of high-dose gamma radiation and particle size on antioxidant properties of Maize ( Zea mays L.) flour

    Energy Technology Data Exchange (ETDEWEB)

    Nawaz, Haq; Shad, Muhammad Aslam; Rehman, Tanzila; Ramzan, Ayesha, E-mail: haqnawaz@bzu.edu.pk [Bahauddin Zakariya University, Multan (Pakistan)

    2016-10-15

    Influence of high-dose gamma radiation and particle size on antioxidant properties of maize (Zea mays L.) flour was studied using response surface methodology. A central composite design based on three levels of each of particle size, in terms of mesh number (40, 60 and 80 meshes), and gamma radiation dose (25, 50 and 75 kGy) was constructed. A statistically significant dose-dependent decrease (p<0.05) in antioxidant properties of gamma irradiated flour was observed. However, an increase in the mesh number (decrease in particle size of flour) resulted in an increase in antioxidant properties. The optimum level of radiation dose to achieve maximum value of responses was found to be 50 kGy for Trolox equivalent total antioxidant activity (TETAOA), 25 kGy for iron chelating ability (ICA), 25 kGy for reducing power (RP) and 75 kGy for linoleic acid reduction capacity (LARC). However, the optimum level of mesh number to achieve desired levels of TETAOA, ICA, RP and LARC was found to be 80 meshes. (author)

  9. Modeling of magnetic fields on a cylindrical surface and associated parameter estimation for development of a size sensor

    International Nuclear Information System (INIS)

    Zhang, Song; Rajamani, Rajesh

    2016-01-01

    This paper develops analytical sensing principles for estimation of circumferential size of a cylindrical surface using magnetic sensors. An electromagnet and magnetic sensors are used on a wearable band for measurement of leg size. In order to enable robust size estimation during rough real-world use of the wearable band, three estimation algorithms are developed based on models of the magnetic field variation over a cylindrical surface. The magnetic field models developed include those for a dipole and for a uniformly magnetized cylinder. The estimation algorithms used include a linear regression equation, an extended Kalman filter and an unscented Kalman filter. Experimental laboratory tests show that the size sensor in general performs accurately, yielding sub-millimeter estimation errors. The unscented Kalman filter yields the best performance that is robust to bias and misalignment errors. The size sensor developed herein can be used for monitoring swelling due to fluid accumulation in the lower leg and a number of other biomedical applications. (paper)

  10. Predictable variation of range-sizes across an extreme environmental gradient in a lizard adaptive radiation: evolutionary and ecological inferences.

    Directory of Open Access Journals (Sweden)

    Daniel Pincheira-Donoso

    Full Text Available Large-scale patterns of current species geographic range-size variation reflect historical dynamics of dispersal and provide insights into future consequences under changing environments. Evidence suggests that climate warming exerts major damage on high latitude and elevation organisms, where changes are more severe and available space to disperse tracking historical niches is more limited. Species with longer generations (slower adaptive responses, such as vertebrates, and with restricted distributions (lower genetic diversity, higher inbreeding in these environments are expected to be particularly threatened by warming crises. However, a well-known macroecological generalization (Rapoport's rule predicts that species range-sizes increase with increasing latitude-elevation, thus counterbalancing the impact of climate change. Here, I investigate geographic range-size variation across an extreme environmental gradient and as a function of body size, in the prominent Liolaemus lizard adaptive radiation. Conventional and phylogenetic analyses revealed that latitudinal (but not elevational ranges significantly decrease with increasing latitude-elevation, while body size was unrelated to range-size. Evolutionarily, these results are insightful as they suggest a link between spatial environmental gradients and range-size evolution. However, ecologically, these results suggest that Liolaemus might be increasingly threatened if, as predicted by theory, ranges retract and contract continuously under persisting climate warming, potentially increasing extinction risks at high latitudes and elevations.

  11. Retrieval of Droplet size Density Distribution from Multiple field of view Cross polarized Lidar Signals: Theory and Experimental Validation

    Science.gov (United States)

    2016-06-02

    Retrieval of droplet-size density distribution from multiple-field-of-view cross-polarized lidar signals: theory and experimental validation...Gilles Roy, Luc Bissonnette, Christian Bastille, and Gilles Vallee Multiple-field-of-view (MFOV) secondary-polarization lidar signals are used to...use secondary polarization. A mathematical relation among the PSD, the lidar fields of view, the scattering angles, and the angular depolarization

  12. Radiation field distribution within the room for three commonly-used interventional procedures

    International Nuclear Information System (INIS)

    Liu Changcai; Zhang Lin; Min Nan; Lu Feng; Li Quantai; Deng Daping; Chen Yue; Zhu Jianguo

    2014-01-01

    Objective: To detect the radiation field distribution within the room for three commonly-used interventional procedures, in order to provide basic data for the radiation protection and safe operation of staff involved in interventional radiology. Methods: The thermoluminescent dosemeters (TLDs) were placed in different points on the horizontal plane around the interventional table and the vertical plane where the staff often stayed. Based on the selected experimental conditions, the TLDs were grouped to be irradiated. After the experiment, the TLDs were measured in the laboratory to calculate the doses of radiation field. Results: Data obtained at the same position followed basically as cardiovascular intervention > cerebrovascular intervention > liver intervention. Intervention of same type at the same position followed as high-dose group > mid-dose group > low-dose group. These results were consistent with the useful beam doses, and proportional to the fluoroscopy time. A few data with exception were due to measurement error or experimental error. Conclusions: Cerebrovasc