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Sample records for routine albedo thermoluminescent

  1. Thermoluminescence albedo-neutron dosimetry

    International Nuclear Information System (INIS)

    Strand, T.; Storruste, A.

    1986-10-01

    The report discusses neutron detection with respect to dosimetry and compares different thermoluminescent dosimetry materials for neutron dosimetry. Construction and calibration of a thermoluminescence albedo neutron dosemeter, developed by the authors, is described

  2. Operational comparison of bubble (super heated drop) dosimetry with routine albedo thermoluminescent dosimetry for a selected group of Pu-238 workers at Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Romero, L.L.; Hoffman, J.M.; Foltyn, E.M.; Buhl, T.E.

    1999-01-01

    This paper is an operational study that compares the use of albedo thermoluminescent dosimeters with bubble dosimeters to determine whether bubble dosimeters do provide a useful daily ALARA tool that can yield measurements close to the dose-of-record. A group of workers at the Los Alamos National Laboratory (LANL) working on the Radioactive Thermoelectric Generators (RTG) for the NASA Cassini space mission wore both bubble dosimeters and albedo dosimeters over a period from 1993 through 1996. The bubble dosimeters were issued and read on a daily basis and the data were used as an ALARA tool. The personnel albedo dosimeter was processed on monthly basis and used as the dose-of-record. The results of this study indicated that cumulative bubble dosimetry results agreed with whole-body albedo dosimetry results within about 37% on average. However it was observed that there is a significant variability of the results on an individual basis both month-to-month and from one individual to another

  3. Characterization of a two-component thermoluminescent albedo dosemeter according to ISO 21909

    Energy Technology Data Exchange (ETDEWEB)

    Martins, M.M., E-mail: marcelo@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN), Av. Salvador Allende s/n, CEP 22780-160, Rio de Janeiro, RJ (Brazil); Mauricio, C.L.P., E-mail: claudia@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN), Av. Salvador Allende s/n, CEP 22780-160, Rio de Janeiro, RJ (Brazil); Pereira, W.W., E-mail: walsan@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN), Av. Salvador Allende s/n, CEP 22780-160, Rio de Janeiro, RJ (Brazil); Silva, A.X. da, E-mail: ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao em Engenharia, COPPE/PEN Caixa Postal 68509, CEP 21941-972, Rio de Janeiro, RJ (Brazil)

    2011-05-15

    A two-component thermoluminescent albedo neutron monitoring system was developed at Instituto de Radioprotecao e Dosimetria, Brazil. As there is no Brazilian regulation for neutron individual monitoring service, the system was tested according to the ISO 21909 standard. This standard provides performance and test requirements for determining the acceptability of personal neutron dosemeters to be used for the measurement of personal dose equivalent, H{sub p}(10), in neutron fields with energies ranging from thermal to 20 MeV. Up to 40 dosemeters were used in order to accomplish satisfactorily the requirements of some tests. Despite operational difficulties, this albedo system passed all ISO 21909 performance requirements. The results and problems throughout this characterization are discussed in this paper.

  4. Quality assurance package for routine thermoluminescence dosimetry program

    International Nuclear Information System (INIS)

    Tawil, R.A.; Bencke, G.; Moscovitch, M.

    1988-01-01

    The Quality Assurance Package presented here specifies a set of reader-related hardware diagnostics and calibration procedures and automatically maintains audit trails of generated and derived thermoluminescence data. It specifies acceptable performance criteria for the reader and dosimeter assemblies; tracks and controls Readout Cycle Temperature Profiles; and ensures that the acquired data is verified. The quality of the generated glow curves is tracked by the real-time application of Computerized Glow Curve Deconvolution to reference dosimeters that may be mixed with field dosimeters during readout sessions. This package is supported by a menu-driven software system using vertical auto-selection menus, lotus-style horizontal menus, data entry menus with automatic error checking, and pop-up windows. The menu system is supported by an extensive HELP file; data EDITING is password-protected, and a journal is maintained for each editing session as part of the audit trail. Files for the Raw Data and Derived Dose results are maintained and managed in seven databases. The paper provides an in-depth analysis of each of the procedures, specifies data validation criteria, and presents samples of the reports generated

  5. BREESE-II: auxiliary routines for implementing the albedo option in the MORSE Monte Carlo code

    International Nuclear Information System (INIS)

    Cain, V.R.; Emmett, M.B.

    1979-07-01

    The routines in the BREESE package implement the albedo option in the MORSE Monte Carlo Code by providing (1) replacements for the default routines ALBIN and ALBDO in the MORSE Code, (2) an estimating routine ALBDOE compatible with the SAMBO package in MORSE, and (3) a separate program that writes a tape of albedo data in the proper format for ALBIN. These extensions of the package initially reported in 1974 were performed jointly by ORNL, Bechtel Power Corporation, and Science Applications, Inc. The first version of BREESE had a fixed number of outgoing polar angles and the number of outgoing azimuthal angles was a function of the value of the outgoing polar angle only. An examination of differential albedo data led to this modified version which allows the number of outgoing polar angles to be dependent upon the value of the incoming polar angle and the number of outgoing azimuthal angles to be a function of the value of both incoming and outgoing polar angles

  6. Development and characterization of two-component albedo based neutron individual monitoring system using thermoluminescent detectors

    International Nuclear Information System (INIS)

    Martins, Marcelo Marques

    2008-01-01

    A TLD-albedo based two-component neutron individual monitoring system was developed and characterized in this work. The monitor consists of a black plastic holder, an incident neutron boron loaded shield, a moderator polyethylene body (to increase its response), two pairs of TLD-600 and TLD-700 (one pair to each component) and an adjustable belt. This monitoring system was calibrated in thermal neutron fields and in 70 keV, 144 keV, 565 keV, 1.2 MeV and 5 MeV monoenergetic neutron fields. In addition, it was calibrated in 252C f(D 2 O), 252 Cf, 241 Am-B, 241 Am-Be and 238 Pu-Be source fields. For the latter, the lower detection levels are, respectively, 0.009 mSv, 0.06 mSv, 0.12 mSv, 0.09 mSv and 0.08 mSv. The participation in an international intercomparison sponsored by IAEA with simulated workplace fields validated the system. The monitoring system was successfully characterized in the ISO 21909 standard and in an IRD - the Brazilian Institute for Radioprotection and Dosimetry - technical regulation draft. Nowadays, the neutron individual system is in use by IRD for whole body individual monitoring of five institutions, which comprehend several activities. (author)

  7. Test of an albedo neutron dosimetry system: TLD calibration and readout procedure, neutron calibration, dosimetry properties, routine application

    International Nuclear Information System (INIS)

    Piesch, E.; Burgkhardt, B.

    1988-03-01

    The two-component albedo dosemeter in use consists of an universal boron-loaded plastic encapsulation, the beta and albedo neutron windows of which are adopted to the corresponding TLD system of the manufacturers Alnor, Harshaw, Panasonic and Vinten. Beside the TLD detectors the capsule may contain also track etch detectors. Within a BMU project the system was investigated by four governmental measurement services in the FRG with respect to its qualification for personnel monitoring with emphasis in the readout and calibration procedures for the TLD system, the evaluation technique for the estimation of the photon and neutron dose equivalent in routine monitoring and the calibration of the personnel dosemeter in stray neutron fields. The test has shown the readiness of the system to act in the application areas of nuclear power reactors and linacs behind heavy shieldings, in the fuel element cycle, use of fissile materials, criticality, use of radionuclide sources, high energy particle accelerators. The uncertainty due to energy dependence was found to be within a factor of 2 for a single application area. In the case of irradiations from the front half space the dose equivalent H'(10) is indicated sufficiently independent of the direction of the radiation incidence. After completion of the test the albedo dosemeter became the official neutron personnel dosemeter in the FRG. It allows the separate estimation of the dose equivalent of hard beta radiation, photon radiation and neutrons. (orig./HP) [de

  8. Development and characterization of two-component albedo based neutron individual monitoring system using thermoluminescent detectors; Desenvolvimento e caracterizacao de um sistema de monitoracao individual de neutrons tipo albedo de duas componentes usando detectores termoluminescentes

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Marcelo Marques

    2008-07-01

    A TLD-albedo based two-component neutron individual monitoring system was developed and characterized in this work. The monitor consists of a black plastic holder, an incident neutron boron loaded shield, a moderator polyethylene body (to increase its response), two pairs of TLD-600 and TLD-700 (one pair to each component) and an adjustable belt. This monitoring system was calibrated in thermal neutron fields and in 70 keV, 144 keV, 565 keV, 1.2 MeV and 5 MeV monoenergetic neutron fields. In addition, it was calibrated in {sup 252C}f(D{sub 2}O), {sup 252}Cf, {sup 241}Am-B, {sup 241}Am-Be and {sup 238}Pu-Be source fields. For the latter, the lower detection levels are, respectively, 0.009 mSv, 0.06 mSv, 0.12 mSv, 0.09 mSv and 0.08 mSv. The participation in an international intercomparison sponsored by IAEA with simulated workplace fields validated the system. The monitoring system was successfully characterized in the ISO 21909 standard and in an IRD - the Brazilian Institute for Radioprotection and Dosimetry - technical regulation draft. Nowadays, the neutron individual system is in use by IRD for whole body individual monitoring of five institutions, which comprehend several activities. (author)

  9. Neutron Albedo

    CERN Document Server

    Ignatovich, V K

    2005-01-01

    A new, algebraic, method is applied to calculation of neutron albedo from substance to check the claim that use of ultradispersive fuel and moderator of an active core can help to gain in size and mass of the reactor. In a model of isotropic distribution of incident and reflected neutrons it is shown that coherent scattering on separate grains in the case of thermal neutrons increases transport cross section negligibly, however it decreases albedo from a wall of finite thickness because of decrease of substance density. A visible increase of albedo takes place only for neutrons with wave length of the order of the size of a single grain.

  10. Intercomparisons to evaluate the suitability of gaschromatographic, electron-spin-resonance spectrometric and thermoluminescence methods to detect irradiated foods in routine control

    International Nuclear Information System (INIS)

    Schreiber, G.A.; Helle, N.; Schulzki, G.; Spiegelberg, A.; Linke, B.; Wagner, U.; Boegl, K.W.

    1993-01-01

    The results of four different intercomparisons to detect irradiated fish and chicken meat containing bones, chicken-, pork-, and beef-meat without bones, spices, herbs as well as spice- and herb mixtures, various fruit and vegetables as well as pistachio nuts using gas chromatographic methods, electron-spin resonance spectroscopy or thermoluminescence analyses are reported. (author)

  11. THERMOLUMINESCENT DOSIMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Malsky, Stanley J.; Amato, Charles G.; Roswit, Bernard

    1963-06-15

    The performance of CaF/sub 2/: Mn and LiF as thermoluminescent in vivo dosimeters is studied. The facility with which this type of dosimeter can be inserted into the body is discussed. The dosimeter is inserted into the body by trocar or catheter techniques and exposed to radiation; it is then removed and heated, and the thermoluminescence is measured and used as an indication of the absorbed dose. (T.F.H.)

  12. Unraveling thermoluminescence

    CERN Document Server

    Sunta, C M

    2014-01-01

    The book is essentially about the theoretical aspects of thermoluminescence (TL). It is structured and written in a manner which will specially be of interest to the fresh undergraduate students and young researchers planning to take up work in the field of thermoluminescence. It is arranged into seven chapters, starting with the historical growth of the subject of TL and an overview of the luminescence phenomena. A Physical model involving thermally disconnected deep traps is specially described. Using this model expressions are derived for the TL intensity growth curve, the supralinearity fa

  13. Thermoluminescence and applications

    International Nuclear Information System (INIS)

    Rodrigues, G.V.

    1986-01-01

    The theory of thermoluminescent emission, the characteristics of main thermoluminescent phosphorus, and some applications are presented. The main thermoluminescent dosemeters used in dosimetry are related. (M.C.K.)

  14. Thermoluminescence and their applications

    International Nuclear Information System (INIS)

    Rodrigues, G.V.

    1986-01-01

    The theory involved in the phenomenon of thermoluminescence emission, the characteristics of the main thermoluminescent phosphorus and some of their applications are presented. Some of the main thermoluminescent dosemeters used in dosimetry are described. (M.C.K.) [pt

  15. Thermoluminescent phosphor

    Science.gov (United States)

    Lasky, Jerome B.; Moran, Paul R.

    1978-01-01

    A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta rays in the presence of a background of more penetrating radiation.

  16. Measurement of TLD Albedo response on various calibration phantoms

    International Nuclear Information System (INIS)

    Momose, T.; Tsujimura, N.; Shinohara, K.; Ishiguro, H.; Nakamura, T.

    1996-01-01

    The International Commission on Radiation Units and Measurements (ICRU) has recommended that individual dosemeter should be calibrated on a suitable phantom and has pointed out that the calibration factor of a neutron dosemeter is strongly influenced by the the exact size and shape of the body and the phantom to which the dosemeter is attached. As the principle of an albedo type thermoluminescent personal dosemeter (albedo TLD) is essentially based on a detection of scattered and moderated neutron from a human body, the sensitivity of albedo TLD is strongly influenced by the incident neutron energy and the calibration phantom. (1) Therefore for albedo type thermoluminescent personal dosemeter (albedo TLD), the information of neutron albedo response on the calibration phantom is important for appropriate dose estimation. In order to investigate the effect of phantom type on the reading of the albedo TLD, measurement of the TLD energy response and angular response on some typical calibration phantoms was performed using dynamitron accelerator and 252 Cf neutron source. (author)

  17. Thermoluminescence dating

    International Nuclear Information System (INIS)

    Price, D.M.

    1999-01-01

    Thermoluminescence (TL) dating of sediments depends upon the acquisition and long term stable storage of TL energy by crystalline minerals contained within a sedimentary unit. This energy is stored in the form of trapped electrons and quartz sand is the most commonly used mineral employed in the dating process. Prior to the final depositional episode it is necessary that any previously acquired TL is removed by exposure to sunlight. After burial the TL begins to build up again at a rate dependent upon the radiation flux delivered by long-lived isotopes of uranium, thorium and potassium. The presence of rubidium and cosmic radiation generally play a lesser but contributory roll, and the total radiation dose delivered to the TL phosphor is modified by the presence of water. The period since deposition is therefore measured by determining the total amount of stored TL energy, the palaeodose (P), and the rate at which this energy is acquired, the annual radiation dose (ARD). TL dating may be applied to eolian, fluvial, coastal and in some cases, marine sediments. the technique is also successfully applied to volcanic materials and to a certain extent to archeological specimens

  18. Thermoluminescence of irradiated foods

    International Nuclear Information System (INIS)

    Wagner, U.; Helle, N.; Boegl, K.W.; Schreiber, G.A.

    1993-01-01

    This report describes developments and applications of the thermoluminescence (TL) analysis of mineral contaminants in foods. Procedures are presented to obtain minerals from most different products such as pepper, mangos, shrimps and mussels. The effect of light exposure during the storage of foods on the TL intensity of minerals is examined and corresponding conclusions for routine control are drawn. It is also shown that the normalization of TL intensities - the essential step to identify irradiated samples - can not only be achieved by γ, X or β rays but also by UV radiation. The results allow the conclusion that a clear identification of any food which has been irradiated with more than 1 kGy is possible if enough minerals can be isolated. (orig.)

  19. Personnel radiation monitoring by thermoluminescence dosimetry (2000-2001)

    International Nuclear Information System (INIS)

    Mi-Cho-Cho, Daw; Hla-Hla-Win, Daw; Thin-Thin-Kraing

    2001-01-01

    Thermoluminescence dosimetry service was introduced in 1991. Personnel who exposed directly or indirectly to radiation is monitored by thermoluminescent dosimeter. TL materials used for thermoluminescent dosimeter are in the form of thin disc. Personnel whole-body and extremity doses are measured by thermoluminescence dosimetry. The Harshaw Model 4500 TLD reader and Vinten 654E TLD reader are used for TLD evaluation. At present about 600 radiation workers are provided with TLD for routine monitoring. It was found that most personnel had received within permissible dose recommended by the International Commission on Radiological Protection (ICRP). (author)

  20. Handbook of thermoluminescence

    CERN Document Server

    Furetta, Claudio

    2010-01-01

    This second edition of the Handbook of Thermoluminescence enlarges on all the subjects which were treated in the first edition and adds further arguments, including the theory of thermoluminescent dose measurement, several examples concerning the kinetics parameters determination using various methods such as peak shape, isothermal decay, and so on. A special section is devoted to food irradiation, an important subject at the present time, and to the thermoluminescent characterization of the minerals extracted from the irradiated food. Another new section is devoted to the thermoluminescent ph

  1. Estimation of daily albedo on Tottori sand surface

    International Nuclear Information System (INIS)

    Gu, S.; Otsuki, K.; Kamichika, M.

    2001-01-01

    Daily albedos of a bare sand surface were measured with a solarimeter (Eko MS-62) between 23 August and 30 November in 1997 at Tottori sand dune, Japan. These quickly decreased on rainy days, and recovered during dry spells (days between rainfalls). A strong exponential relationship was found between daily albedos and the number of dry days. The daily albedos on dry days also showed a direct relationship with daily transmissivities in the range less than 0.55. Two simple models were developed to estimate daily albedos for dry spell days on bare Tottori sand surface using routine meteorological data. Daily albedos were calculated using these two models, and compared with the measured daily albedos. For Model #1, the daily albedos were successfully predicted only using the number of dry spell days; the correlation coefficient between the estimated and measured albedo was 0.73, and the standard error was 1.2%. For Model #2, the number of dry spell days and transmissivity were considered in order to calculate the daily albedo on dry spell days; the correlation coefficient was 0.85, and the standard error was 0.9%. Estimated albedos were in good agreement with measured albedos. (author)

  2. Thermoluminescent dosimeter system

    International Nuclear Information System (INIS)

    Felice, P.E.; Gonzalez, J.L.; Seidel, J.G.

    1979-01-01

    An improved thermoluminescent dosimeter system and apparatus for sensing alpha particle emission is described. A thermoluminescent body is sealed between a pair of metallized plastic films. The dosimeter is mounted within a protective inverted cup or a tube closed at one end, which is disposed in a test hole for exposure to radioactive radon gas which is indicaive of uranium deposits

  3. Observations of Surfzone Albedo

    Science.gov (United States)

    Sinnett, G.; Feddersen, F.

    2014-12-01

    The surfzone environment (where waves break) contains several unique and previously unconsidered processes that affect the heat budget. Entering short-wave radiation is a dominant term in both shelf and surfzone heat budgets. In contrast to the shelf, however, depth limited wave breaking in the surfzone generates spray, whitewater and suspended sediments, elevating the surface albedo (ratio of reflected to incident short-wave radiation). Elevated albedo reduces the level of solar short-wave radiation entering the water, potentially resulting in less heating. Additionally, surfzone water quality is often impacted by fecal bacteria contamination. As bacteria mortality is related to short-wave solar radiation, elevated surfzone albedo could reduce pathogen mortality, impacting human health. Albedo in the open ocean has been frequently studied and parameterizations often consider solar zenith angle, wind speed and ocean chlorophyll concentration, producing albedo values typically near 0.06. However, surfzone albedo observations have been extremely sparse, yet show depth limited wave breaking may increase the albedo by nearly a factor of 10 up to 0.5. Here, we present findings from a field study at the Scripps Institution of Oceanography pier to observe the affect of waves on surfzone albedo. Concurrent measurements were taken with a four-way radiometer (to measure both downwelling and upwelling short-wave and long wave radiation) mounted above the surfzone. A co-located GoPro camera was used to relate visual aspects of the surfzone to measured reflectance, and wave height and period were observed with a bottom mounted pressure sensor in 5 m water depth just outside the surfzone. Wind speed and direction were observed on the pier 10 m above the water surface. Here, we will examine the surfzone albedo dependence on surfzone parameters, such as wave height.

  4. Equipment for observing thermoluminescence

    International Nuclear Information System (INIS)

    Sette Camara, Alexandre; Cogneau, Michel; Ristori, Christian; Vargas, Jose Israel

    1971-06-01

    A detailed description is given of an apparatus for investigating thermoluminescence properties. Chopping of the emitted light and subsequent amplification of the electric signal derived led to high stability and sensitivity [fr

  5. Preparation of thermoluminescent materials

    International Nuclear Information System (INIS)

    1976-01-01

    Thermoluminescent materials have been found to be suitable for measuring long term exposures to low level ionizing radiation. Oxyhalides of lanthanum, gadolinium and yttrium, including the oxychlorides and oxybromides are activated with terbium and have been found to be most efficient oxygendominated phosphors having thermoradiant efficiencies with excitation by low level ionizing radiation. Thermoluminescence response increases when the previous materials have hafnium and zirconium additives

  6. Calibration of an ALBEDO termoluminiscent dosimeter for its use in personal dosimetry

    International Nuclear Information System (INIS)

    Diaz Bernal, E.; Molina Perez, D.; Cornejo Diaz, N.; Carrazana Gonzalez, J.

    1996-01-01

    The dosimetric studies began after the Radiological Individuals Surveillance Department from the Radiation Protection and Hygiene Center acquired the albedo thermoluminescent dosimeters model JR1104. This paper reviews the response of those dosimeters to the different spectrums and incidence angles of neutronic radiation

  7. Dental tissue as a thermoluminescence dosimetry dosimeter

    International Nuclear Information System (INIS)

    Solaimani, F.; Zahmatkesh, M.H.; Akhlaghpoor, Sh.

    2003-01-01

    Background: Thermoluminescence dosimetry is one of the dosimetry procedures used widely as routine and personal dosimeters. In order to extend this kind of dosimeters, dental tissue has been examined and was found promising as a Thermoluminescence Dosimetry dosimeter. Materials and Methods: In this study, 70 health teeth were collected. The only criterion, wich was considered for selection of the teeth, was the healthiness of them regardless of age and gender of the donors. All collected samples were washed and cleaned and milled uniformly. The final powder had a uniform grain size between 100-300 micrometer. The sample was divided into four groups. Group A and B were used for measurement of density and investigation of variation of thermoluminescent characteristics with temperature respectively. Groups C and D were used for investigation of variation of thermoluminescent intensity with dose and fading of this intensity with time. In all cases the results obtained with dental tissue were compared to a standard LiF, thermoluminescence dosimetry dosimeter. Results: It was found that, average density of the dental tissue was 1.570 g/cm 3 , which is comparable to density of LiF, which is 1.612g/cm 3 . It was also concluded that the range of 0-300 d ig C , dental tissue has a simple curve with two specific peaks at 140 and 25 d ig C respectively. The experiment also showed that, the variation of relative intensity versus dose is linear in the range of 0.04-0.1 Gy. The fading rate of dental tissue is higher than LiF but still in the acceptable range (14% per month in compare to 5.2% per month). Conclusion: Dental tissue as a natural dosimeter is comparable with Thermoluminescence Dosimetry and can be used in accidental events with a good approximation

  8. Thermoluminescence and chemiluminescence measurement as routine screening method for identification of irradiated spices. Studies to establish limiting values for differentiation of irradiated and non-irradiated samples. Thermolumineszenz- und Chemilumineszenzmessungen als Routine-Methoden zur Identifizierung strahlenbehandelter Gewuerze. Untersuchungen zur Festlegung von Grenzwerten fuer die Unterscheidung bestrahlter von unbestrahlten Proben

    Energy Technology Data Exchange (ETDEWEB)

    Heide, L; Albrich, S; Mentele, E; Boegl, W

    1987-04-01

    The reported experiments with non-irradiated and ..gamma..-irradiated spices of different origin were conducted to determine the variation in chemiluminescence and thermoluminescence intensity for each individual spice. 29 spices from 7 to 10 different manufacturers have been examined, taking into account the influence of storage time. In order to evaluate the methods, the results are represented in diagrams and tables enabling light emission limits to be given for differentiation between irradiated and non-irradiated samples. The final section of this report contains a conclusive evaluation of the present state of chemiluminescence and thermoluminescence analysis for the detection of irradiated spices.

  9. Thermoluminescence dating method

    International Nuclear Information System (INIS)

    Zink, A.

    2004-01-01

    A crystal that is submitted to radiation stores energy and releases this energy under the form of light whenever it is heated. These 2 properties: the ability to store energy and the ability to reset the energy stored are the pillars on which time dating methods like thermoluminescence are based. A typical accuracy of the thermoluminescence method is between 5 to 7% but an accuracy of 3% can be reached with a sufficient number of measurement. This article describes the application of thermoluminescence to the dating of a series of old terra-cotta statues. This time measurement is absolute and does not require any calibration, it represents the time elapsed since the last heating of the artifact. (A.C.)

  10. Thermoluminescence dating of pottery

    International Nuclear Information System (INIS)

    Higashimura, Takenobu; Ichikawa, Yoneta.

    1978-01-01

    This report is divided into two parts. The first half describes on the history of thermoluminescence dating, and the latter half, the principle and measurement examples. It was in late 1955 that the measurement of radiation dose using thermoluminescence began. The method to thermoluminescence dating was developed when it was found that most natural stones emit the thermoluminescence. About Greek earthen wares, the study of which was presented in 1961 by G. Kennedy of University of California, the dating was able to be made within the standard deviation of 10%. Since then, this dating method progressed rapidly, and a number of laboratories are now forwarding the investigation. In the samples of natural materials, intensity of thermoluminescence I is proportional to natural radiation dose D which has been absorbed by the samples, i.e. I = kD, where k is the susceptibility of thermoluminescence of the samples. Since k is different in each sample, D can be determined by irradiating the sample with β or γ ray of known dose D 0 , measuring its luminescence I 0 , and eliminating k through these two equations, because i 0 = kD 0 . Next, if t is assumed to be the time passed since a pottery was made, D is expressed as Rt, where R is the natural radiation dose per year absorbed by the pottery. Thus t is determined if R is known. The report describes on the method of measuring R. As an example, the results of measurement of the potteries excavated at Iwakura remains, Yorikura, Taishaku-kyo, are listed. Results by 14 C dating are also described for reference. (Wakatsuki, Y.)

  11. Thermoluminescence from natural calcites

    International Nuclear Information System (INIS)

    Calderon, T.; Jaque, F.; Coy-yll, R.

    1984-01-01

    Thermoluminescence (TL) as well as absorption and EPR spectra of x-irradiated natural calcites have been obtained. Irradiation produces UV absorption bands and a decrease of the Mn 2+ EPR spectrum. A correlation of each TL peak with the bleaching steps of UV absorption bands and the recovering in intensity of the Mn 2+ EPR spectrum has been found. These experimental results support a new model for the radiation damage and thermoluminescence process in calcites. The main point in this model is that holes become trapped at impurities, and the electrons are trapped at dislocations in the form of CO 3 3- . (author)

  12. A microcomputer controlled thermoluminescence dosimetry system

    International Nuclear Information System (INIS)

    Huyskens, C.J.; Kicken, P.J.H.

    1980-01-01

    Using a microcomputer, an automatic thermoluminescence dosimetry system for personal dosimetry and thermoluminescence detector (TLD) research was developed. Process automation, statistical computation and dose calculation are provided by this microcomputer. Recording of measurement data, as well as dose record keeping for radiological workers is carried out with floppy disk. The microcomputer also provides a human/system interface by means of a video display and a printer. The main features of this dosimetry system are its low cost, high degree of flexibility, high degree of automation and the feasibility for use in routine dosimetry as well as in TLD research. The system is in use for personal dosimetry, environmental dosimetry and for TL-research work. Because of its modular set-up several components of the system are in use for other applications, too. The system seems suited for medium sized health physics groups. (author)

  13. Thermoluminescence of strontium tetraborate

    International Nuclear Information System (INIS)

    Santiago, M.; Caselli, E.; Lester, M.

    1999-01-01

    The thermoluminescent properties of crystalline strontium tetraborate are reported. Without activators it has an efficiency comparable to that of TLD-700 powder. Its fading after 40 days amount to less than 2%. The isometric plot shows that most of the emitted light is concentrated at wavelengths ranging from 350 to 450 nm, which accounts partially for the high efficiency. (author)

  14. Instrumentation in thermoluminescence dosimetry

    International Nuclear Information System (INIS)

    Julius, H.W.

    1986-01-01

    In the performance of a thermoluminescence dosimetry (TLD) system the equipment plays an important role. Crucial parameters of instrumentation in TLD are discussed in some detail. A review is given of equipment available on the market today - with some emphasis on automation - which is partly based on information from industry and others involved in research and development. (author)

  15. TELDE thermoluminescent dosimetry system

    International Nuclear Information System (INIS)

    Shvarts, K.K.; Nemiro, E.A.; Bichev, V.R.; Gotlib, V.I.; Grant, Z.A.; Grube, M.M.; Gubatova, D.J.

    1981-01-01

    The TELDE dosimetric set designed for measurement of x- and γ- rays doses with energy more than 10 keV is described. The set consists of thermoluminescent detectors from LiF (Ca, Mg, Ti). The detectors are polycrystalline pellets with diameter 3.5+-0.3 mm and thickness 2+-0.2 mm. In the thermoluminescence detectors both the peak and integral measurement methods are realized. Apart from this the TELDE set comprises the electron unit for the pre-irradiation thermal treatment of detectors, special bones for detectors storage and transportation, devices for their package in polyethelene film and containers to wear the detectors. The TELDE set allows to perform measurements on people or animals in radiobiological experiments as well as in water, solid or porous phantoms [ru

  16. Thermoluminescent dosimetry: theory, materials and applications

    International Nuclear Information System (INIS)

    Rosa, L.A.R.da.

    1978-01-01

    A survey about the thermoluminescence theory, the properties of the main thermoluminescent phosphors and their applications is presented. Some of the most important thermoluminescent readers are also mentioned [pt

  17. Thermoluminescence studies in geology

    International Nuclear Information System (INIS)

    Sankaran, A.V.; Sunta, C.M.; Nambi, K.S.V.; Bapat, V.N.

    1980-01-01

    Even though the phenomenon of thermoluminescence is well studied, particularly over last 3 decades, its potentialities in the field of geology have not been adequately evaluated. In this report several useful applications of TL in mineralogy, petrogenesis, stratigraphy, tectonics, ore-prospecting and other branches have been identified with particular emphasis to the Indian scene. Important areas in the country that may provide the basic material for such studies are indicated at the end along with brief geological or mineralogical accounts. (auth.)

  18. Thermoluminescence spectra of amethyst

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q. [Suzhou Railway Teachers College (China). Dept. of Physics; Yang, B. [Beijing Normal University (China). Dept. of Physics; Wood, R.A.; White, D.R.R.; Townsend, P.D.; Luff, B.J. [Sussex Univ., Brighton (United Kingdom). School of Mathematical and Physical Sciences

    1994-04-01

    Thermoluminescence and cathodoluminescence data from natural and synthetic amethyst and synthetic quartz samples are compared. The spectra include features from the quartz host lattice and from impurity-generated recombination sites. Emission features exist throughout the wavelength range studied, 250-800 nm. The near infrared emission at 740-750 nm appears to be characteristic of the amethyst and is proposed to be due to Fe ion impurity. (Author).

  19. Thermoluminescence - physics and applications

    International Nuclear Information System (INIS)

    Sunta, C.M.

    1992-01-01

    The interaction of ionizing radiations with matter leads to various effects, some of which leave memory in the target material. These memory effects can be seen as the after-effects of the irradiation. Thermoluminescence is one such phenomenon in the insulating solids. This paper describes the sequence of the physical events beginning with the incidence of an ionizing particle, leading to a trail of atomic and electronic displacements which stabilize in the form of so called defect centres. These defects - interstitials, colour centres, etc., store energy in their configuration. Most of the damage effects are reversible. The return of the displaced entities to their original site leads to the release of the stored energy. Thermoluminescence is the result of the re-adjustment (relaxation) of the displaced electrons. The stimulation for the relaxation process is provided by heating of the irradiated sample. The kinetics of the thermoluminescence process has been explained phenomenologically. The correspondence between the defect centres and the TL glow peaks has remained vague or ambiguous even in the most widely studied TL materials. Notwithstanding this deficiency, the phenomenon has found many practical applications. The paper deals mainly with the physical processes involved in the TL emission and alludes briefly to its involvement in applied areas.(author). 6 refs., 2 figs

  20. Thermoluminescence: its understanding and applications

    International Nuclear Information System (INIS)

    Nambi, K.S.V.

    1977-01-01

    The phenomenon of thermoluminescence is treated exhaustively both mathematically and physically. All the possible applications of the phenomenon are briefly described and an optimistic picture of the future trends in this field is projected. A review of latest information on thermoluminescence instrumentation and phosphors is also included [pt

  1. Thermoluminescence of pyramid stones

    International Nuclear Information System (INIS)

    Gomaa, M.A.; Eid, A.M.

    1982-01-01

    It is the aim of the present study to investigate some thermoluminescence properties of pyramid stones. Using a few grammes of pyramid stones from Pyramids I and II, the TL glow peaks were observed at 250 and 310 0 C, respectively. The TL glow peaks of samples annealed at 600 0 C, then exposed to 60 Co γ-rays were observed at 120, 190 and 310 0 C, respectively. The accumulated dose of natural samples is estimated to be around 310 Gray (31 krad). By assuming an annual dose is 1 mGy, the estimated age of pyramid stones is 0.31 M year. (author)

  2. Thermoluminescence of pyramid stones

    Energy Technology Data Exchange (ETDEWEB)

    Gomaa, M A; Eid, A M [Atomic Energy Establishment, Cairo (Egypt)

    1982-01-01

    It is the aim of the present study to investigate some thermoluminescence properties of pyramid stones. Using a few grammes of pyramid stones from Pyramids I and II, the TL glow peaks were observed at 250 and 310/sup 0/C, respectively. The TL glow peaks of samples annealed at 600/sup 0/C, then exposed to /sup 60/Co ..gamma..-rays were observed at 120, 190 and 310/sup 0/C, respectively. The accumulated dose of natural samples is estimated to be around 310 Gray (31 krad). By assuming an annual dose is 1 mGy, the estimated age of pyramid stones is 0.31 M year.

  3. Thermoluminescent system for low temperatures

    International Nuclear Information System (INIS)

    Rosa, L.A.R. da; Caldas, L.V.E.; Leite, N.G.

    1988-09-01

    A system for measurements of the thermoluminescent glow curve, the thermoluminescent emission spectrum and the optical absorption spectrum of solid samples, from liquid nitrogen temperature up to 473 K, is reported. A specially designed temperature programmer provides a linear heating of the sample at a wide range of selectable heating rates, as also long term steady-state temperatures for annealing and isothermal decay studies. The system operates at a pressure of 1.33 x 10 -3 Pa. Presently it is being used for lithium fluoride low temperature thermoluminescent studies. (author) [pt

  4. Thermoluminescence in medical dosimetry

    International Nuclear Information System (INIS)

    Rivera, T.

    2011-10-01

    The dosimetry by thermoluminescence (Tl) is applied in the entire world for the dosimetry of ionizing radiations specially to personal and medical dosimetry. This dosimetry method has been very interesting for measures in vivo because the Tl dosimeters have the advantage of being very sensitive in a very small volume and they are also equivalent to tissue and they do not need additional accessories (for example, cable, electrometer, etc.) The main characteristics of the diverse Tl materials to be used in the radiation measures and practical applications are: the Tl curve, the share homogeneity, the signal stability after the irradiation, precision and exactitude, the response in function with the dose and the energy influence. In this work a brief summary of the advances of the radiations dosimetry is presented by means of the thermally stimulated luminescence and its application to the dosimetry in radiotherapy. (Author)

  5. Thermo-luminescent dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Reither, M; Schorn, B; Schneider, E

    1981-01-01

    The development of paediatric radiology which began in the late 195O's has been characterised by the need to limit the dose of ionising radiation to which the child is subjected. The aim has been to keep radiation exposure as low as possible by the introduction of suitable techniques and by the development of new methods. It is therefore surprising that studies in dosimetry in the paediaytric age range have only been carried out in recent years. One reason for this may have been the fact that a suitable technique of measurement was not available at the time. The introduction of solid state dosimetry based on thermo-luminescence, first into radiotherapy (1968) and subsequently into radiodiagnosis, has made it possible to abandon the previously widely used ionisation chamber. The purpose of the present paper is to indicate the suitability of this form of dose measurement for paediatric radiological purposes and to stimulate its application in this field.

  6. Mexican gems as thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    Azorin N, J.

    1979-01-01

    The possibility of using naturally ocurring mexican gems as thermoluminescent dosimeters (TLD) was investigated. Twelve types of gems were irradiated with X and gamma rays in order to determinate their dosimetric properties. Three of these gems showed favorable thermoluminescent characteristics compared with commercial thermoluminescent dosimeters. The plots of their thermoluminescent response as a function of gamma dose are straight lines on full log paper in the dose range 10 -2 to 10 2 Gy. The energy dependence is very strong to low energies of the radiation. Their fading was found to be about 5%/yr. and they may be annealed as reused without loss in sensitivity. Therefore, these gems can be used as X and gamma radiation dosimeters. (author)

  7. Proposal of requirements for performance in Brazil for systems of external individual monitoring for neutrons applying the TLD-albedo technique

    International Nuclear Information System (INIS)

    Martins, Marcelo M.; Mauricio, Claudia L.P.; Pereira, Walsan W.; Fonseca, Evaldo S. da; Silva, Ademir X.

    2009-01-01

    This work presents a criteria and conditions proposal for the regulations in Brazil of individual monitoring systems for neutrons applying the albedo technique with thermoluminescent detectors. Tests are proposed for the characterization performance of the system based on the Regulation ISO 21909 and on the experience of the authors

  8. An optical fibre-type silicate glass thermoluminescent detector

    International Nuclear Information System (INIS)

    Zheng Zheng; Dai Honggui; Hu Shangze; Liu Jian; Fang Jie

    1991-01-01

    A description of dosimetric properties and the preparation method of an optical fibre-type silicate glass thermoluminescent detector (TLD) is presented. Results showed that this new phosphor is a good one which could be used as a routine dosimeter in the range 10 -1 -10 3 Gy. The preparation method is a new one which differs greatly from all previous ones. Furthermore this kind of detector is small and of low weight. (orig.)

  9. Brazilian two-component TLD albedo neutron individual monitoring system

    Energy Technology Data Exchange (ETDEWEB)

    Martins, M.M., E-mail: marcelo@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD), Av. Salvador Allende, s/n, CEP: 22780-160, Rio de Janeiro, RJ (Brazil); Mauricio, C.L.P., E-mail: claudia@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD), Av. Salvador Allende, s/n, CEP: 22780-160, Rio de Janeiro, RJ (Brazil); Fonseca, E.S. da, E-mail: evaldo@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD), Av. Salvador Allende, s/n, CEP: 22780-160, Rio de Janeiro, RJ (Brazil); Silva, A.X. da, E-mail: ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao em Engenharia, COPPE/PEN Caixa Postal 68509, CEP: 21941-972, Rio de Janeiro, RJ (Brazil)

    2010-12-15

    Since 1983, Instituto de Radioprotecao e Dosimetria, Brazil, uses a TLD one-component albedo neutron monitor, which has a single different calibration factor specifically for each installation type. In order to improve its energy response, a two-component albedo monitor was developed, which measure the thermal neutron component besides the albedo one. The two-component monitor has been calibrated in reference neutron fields: thermal, five accelerator-produced monoenergetic beams (70, 144, 565, 1200 and 5000 keV) and five radionuclide sources ({sup 252}Cf, {sup 252}Cf(D{sub 2}O), {sup 241}Am-Be, {sup 241}Am-B and {sup 238}Pu-Be) at several distances. Since January 2008, mainly Brazilian workers who handle neutron sources at different distances and moderation, such as in well logging and calibration facilities are using it routinely.

  10. Dose measurements in dental radiology using thermoluminescent dosimetry

    International Nuclear Information System (INIS)

    Chiara, Ana Claudia M. de; Costa, Alessandro M.; Pardini, Luiz Carlos

    2009-01-01

    The aim of this work was the implementation of a code of practice for dosimetry in dental radiology using the technique of thermoluminescent dosimetry. General principles for the use of thermoluminescent dosimeters were followed. The irradiations were performed using ten X-ray equipment for intra-oral radiography and an X-ray equipment for panoramic radiography. The incident air kerma was evaluated for five different exposure times used in clinical practice for intra-oral radiographs. Using a backscatter factor of 1.2, it was observed that approximately 40% of the entrance skin dose values found for intra-oral radiographs are above the diagnostic reference level recommended in national regulation. Different configurations of voltage and current were used representing the exposure as a child, woman and man for panoramic radiographs. The results obtained for the air kerma area product were respectively 53.3 +- 5.2 mGy.cm 2 , 101.5 +- 9.5 mGy.cm 2 and 116.8 +- 10.4 mGy.cm 2 . The use of thermoluminescent dosimetry requires several procedures before a result is recorded. The use of dosimeters with ionization chambers or semiconductors provides a simple and robust method for routine measurements. However, the use of thermoluminescent dosimetry can be of great value to large-scale surveys to establish diagnostic reference levels. (author)

  11. Evaluation of new and conventional thermoluminescent phosphors for environmental monitoring using automated thermoluminescent dosimeter readers

    International Nuclear Information System (INIS)

    Rathbone, B.A.; Endres, A.W.; Antonio, E.J.

    1994-10-01

    In recent years, there has been considerable interest in a new generation of super-sensitive thermoluminescent (TL) phosphors for potential use in routine personnel and environmental monitoring. Two of these phosphors, α-Al 2 O 3 :C and LiF:Mg,Cu,P, are evaluated in this paper for selected characteristics relevant to environmental monitoring, along with two conventional phosphors widely used in environmental monitoring, LiF:Mg,Ti and CaF 2 :Dy. The characteristics evaluated are light-induced fading, light-induced background, linearity and variability at low dose, and the minimum measurable dose. These characteristics were determined using an automated commercial dosimetry system (Harshaw System 8800) and routine processing protocols. Annealing and readout protocols for each phosphor were optimized for use in a large-scale environmental monitoring program

  12. Proposal of requirements for performance in Brazil for systems of external individual monitoring for neutrons applying the TLD-albedo technique; Proposta de requisitos de desempenho no Brasil para sistemas de monitoracao individual externa para neutrons empregando a tecnica TLD-albedo

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Marcelo M.; Mauricio, Claudia L.P.; Pereira, Walsan W.; Fonseca, Evaldo S. da, E-mail: marcelo@ird.gov.b, E-mail: claudia@ird.gov.b, E-mail: walsan@ird.gov.b, E-mail: evaldo@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Silva, Ademir X., E-mail: ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), RJ (Brazil).

    2009-07-01

    This work presents a criteria and conditions proposal for the regulations in Brazil of individual monitoring systems for neutrons applying the albedo technique with thermoluminescent detectors. Tests are proposed for the characterization performance of the system based on the Regulation ISO 21909 and on the experience of the authors

  13. Field calibration of a TLD albedo dosemeter in the high-energy neutron field of CERF

    International Nuclear Information System (INIS)

    Haninger, T.; Kleinau, P.; Haninger, S.

    2017-01-01

    The new albedo dosemeter-type AWST-TL-GD 04 has been calibrated in the CERF neutron field (CERN-EU high-energy Reference Field). This type of albedo dosemeter is based on thermoluminescent detectors (TLDs) and used by the individual monitoring service of the Helmholtz Zentrum Muenchen (AWST) since 2015 for monitoring persons, who are exposed occupationally against photon and neutron radiation. The motivation for this experiment was to gain a field specific neutron correction factor N n for workplaces at high-energy particle accelerators. N n is a dimensionless factor relative to a basic detector calibration with 137 Cs and is used to calculate the personal neutron dose in terms of H p (10) from the neutron albedo signal. The results show that the sensitivity of the albedo dosemeter for this specific neutron field is not significantly lower as for fast neutrons of a radionuclide source like 252 Cf. The neutron correction factor varies between 0.73 and 1.16 with a midrange value of 0.94. The albedo dosemeter is therefore appropriate to monitor persons, which are exposed at high-energy particle accelerators. (authors)

  14. Thermoluminescence dosimetry environmental monitoring system

    International Nuclear Information System (INIS)

    Bortoluzzi, S.

    1989-01-01

    In this report, characteristics and performances of an environmental monitoring system with thermoluminescence dosimetry are presented. Most of the work deals with the main physical parameters necessary for measurements of ambiental dose. At the end of this report some of level doses in the environment around the site of the ENEA Center of Energy Research Salluggia (Italy) are illustrated

  15. SAI/EPRI Albedo Information Library

    International Nuclear Information System (INIS)

    Simmons, G.L.

    1979-03-01

    The SAI/EPRI Albedo Information Library (SAIL) is described. This description included the techniques used to develop the data and comparisons with albedo data. Albedo data are presented for Type 04 Concrete and Low Carbon Steel, the most common materials encountered in radiation streaming analysis. Applications of the SAIL data are presented and compared with experimental results

  16. Albedo matters: Understanding runaway albedo variations on Pluto

    Science.gov (United States)

    Earle, Alissa M.; Binzel, Richard P.; Young, Leslie A.; Stern, S. A.; Ennico, K.; Grundy, W.; Olkin, C. B.; Weaver, H. A.; New Horizons Surface Composition Theme

    2018-03-01

    The data returned from NASA's New Horizons reconnaissance of the Pluto system show striking albedo variations from polar to equatorial latitudes as well as sharp longitudinal boundaries. Pluto has a high obliquity (currently 119°) that varies by 23° over a period of less than 3 million years. This variation, combined with its regressing longitude of perihelion (360° over 3.7 million years), creates epochs of "Super Seasons" where one pole is pointed at the Sun at perihelion, thereby experiencing a short, relatively warm summer followed by its longest possible period of winter darkness. In contrast, the other pole experiences a much longer, less intense summer and a short winter season. We use a simple volatile sublimation and deposition model to explore the relationship between albedo variations, latitude, and volatile sublimation and deposition for the current epoch as well as historical epochs during which Pluto experienced these "Super Seasons." Our investigation quantitatively shows that Pluto's geometry creates the potential for runaway albedo and volatile variations, particularly in the equatorial region, which can sustain stark longitudinal contrasts like the ones we see between Tombaugh Regio and the informally named Cthulhu Regio.

  17. Selected references on thermoluminescent dosemeters for personnel monitoring

    International Nuclear Information System (INIS)

    Lawson, Helen

    1976-08-01

    This bibliography contains references on: specific thermoluminescent dosemeters used for personnel dosimetry; comparisons of thermoluminescent and other dosemeters for personnel monitoring and read-out apparatus for thermoluminescent dosemeters. An appendix contains selected foreign language references. (author)

  18. Thermoluminescence, a universal tool for dosimetry

    International Nuclear Information System (INIS)

    Barthe, J.

    1999-01-01

    Radio-thermoluminescence is a transient light emission occurring when certain substances, which have been exposed to ionizing radiation, are heated. Under some conditions the quantity of emitted light is proportional to the absorbed dose. This linearity allows thermoluminescence to be used in various fields such as dosimetry, geology and age determination. Dosimeters based on thermoluminescence are passive, they do not require a source of energy and they can sustain high temperatures and high levels of irradiation. Thermoluminescence has been applied for determining the dose absorbed by meteorites and lunar rocks

  19. Study on the fast neutron sensitivity of thermoluminescent detectors

    International Nuclear Information System (INIS)

    Szabo, P.P.; Palfalvi, J.

    1984-03-01

    Fast neutron (14.7 MeV) sensitivity of several thermoluminescent detectors was determined. The investigated detectors were MTS-N type pellets (made in Poland) used routinely in the authors' institute for personnel dosimetry, 7 LiF powder used for accident dosimetry, CaSO 4 :Dy and CaSO 4 :Tm powders (made in Hungary) used for enviromental monitoring and space dosimetry. Both free-in-air and on-phantom irradiations were performed. The new results are compared with responses calculated and measured earlier. (author)

  20. Neutron albedo effects of underground nuclear explosion

    International Nuclear Information System (INIS)

    Yang Bo; Ying Yangjun; Li Jinhong; Bai Yun

    2013-01-01

    The neutron field distribution is affected by the surrounding medium in the underground nuclear explosion. It will influence the radiation chemical diagnosis. By Monte Carlo simulation, the fuel burnup induced by device and neutron albedo was calculated. The analysis method of albedo effect on radiation chemical diagnosis result under special environment was proposed. Neutron albedo should be considered when capture reaction burnup fraction is used, and then correct analysis can be carried out on the nuclear device.The neutron field distribution is affected by the surrounding medium in the underground nuclear explosion. It will influence the radiation chemical diagnosis. By Monte Carlo simulation, the fuel burnup induced by device and neutron albedo was calculated. The analysis method of albedo effect on radiation chemical diagnosis result under special environment was proposed. Neutron albedo should be considered when capture reaction burnup fraction is used, and then correct analysis can be carried out on the nuclear device. (authors)

  1. The Ultraviolet Albedo of Ganymede

    Science.gov (United States)

    McGrath, Melissa; Hendrix, A.

    2013-10-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede’s stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede’s UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values. References Carlson, R. and 39 co-authors, Near-infrared spectroscopy and spectral mapping of Jupiter and the Galilean satellites: Results from Galileo’s initial orbit, Science, 274, 385-388, 1996. Eviatar, A., D. F. Strobel, B. C. Wolven, P. D. Feldman, M. A. McGrath, and D. J. Williams, Excitation of the Ganymede ultraviolet aurora, Astrophys. J, 555, 1013-1019, 2001. Feldman, P. D., M. A. McGrath, D. F. Strobel, H. W. Moos, K. D. Retherford, and B. C. Wolven, HST/STIS imaging of ultraviolet aurora on Ganymede, Astrophys. J, 535, 1085-1090, 2000. McGrath M. A., Lellouch E., Strobel D. F., Feldman P. D., Johnson R. E., Satellite Atmospheres, Chapter 19 in Jupiter: The Planet, Satellites and Magnetosphere, ed. F. Bagenal, T. Dowling, W. McKinnon, Cambridge University Press, 2004. McGrath M. A., Jia, Xianzhe; Retherford, Kurt; Feldman, Paul D.; Strobel, Darrell F.; Saur, Joachim, Aurora on Ganymede, J. Geophys. Res., doi: 10.1002/jgra.50122, 2013. Saur, J., S. Duling, S., L. Roth, P. D. Feldman, D. F. Strobel, K. D. Retherford, M. A. McGrath, A. Wennmacher, American Geophysical Union, Fall Meeting

  2. Thermoluminescent measurement in space radiation dosimetry

    International Nuclear Information System (INIS)

    Chen Mei; Qi Zhangnian; Li Xianggao; Huang Zengxin; Jia Xianghong; Wang Genliang

    1999-01-01

    The author introduced the space radiation environment and the application of thermoluminescent measurement in space radiation dosimetry. Space ionization radiation is charged particles radiation. Space radiation dosimetry was developed for protecting astronauts against space radiation. Thermoluminescent measurement is an excellent method used in the spaceship cabin. Also the authors mentioned the recent works here

  3. Clay as Thermoluminescence Dosemeter in diagnostic Radiology ...

    African Journals Online (AJOL)

    This paper reports the investigation of the basic thermoluminescence properties of clay at x-rays in the diagnostic radiology range, including dose monitoring in abdominal radiography. Clay sourced from Calabar, Nigeria, was tested for thermoluminescence response after irradiation at diagnostic radiology doses, including ...

  4. Numerical analysis of thermoluminescence glow curves

    International Nuclear Information System (INIS)

    Gomez Ros, J. M.; Delgado, A.

    1989-01-01

    This report presents a method for the numerical analysis of complex thermoluminescence glow curves resolving the individual glow peak components. The method employs first order kinetics analytical expressions and is based In a Marquart-Levenberg minimization procedure. A simplified version of this method for thermoluminescence dosimetry (TLD) is also described and specifically developed to operate whit Lithium Fluoride TLD-100. (Author). 36 refs

  5. Thermoluminescence spectra measured with a Michelson interferometer

    International Nuclear Information System (INIS)

    Haschberger, P.

    1991-01-01

    A Michelson interferometer was redesigned to prove its capabilities in the measurement of short-lived, low-intensity thermoluminescence spectra. Interferograms are collected during heating up the thermoluminescent probe in a heater plate. A personal computer controls the data acquisition and processes the Fourier transform. As the results show, even a comparatively simple and limited setup leads to relevant and reproducible spectra. (author)

  6. Detection of irradiated spices by thermoluminescence analysis

    International Nuclear Information System (INIS)

    Hammerton, K.M.; Banos, C.

    1996-01-01

    Spices are used extensively in prepared foods. The high levels of contamination of many spices with microorganisms poses a problem for the food industry. Irradiation treatment is the most effective means of reducing the microbial load to safe levels. Although the process is currently subject to a moratorium in Australia, it is used in several countries for the decontamination of spices. Methods for detecting irradiation treatment of spices are necessary to enforce compliance with labelling requirements or with a prohibition on the sale of irradiated foods. Thermoluminescence (TL) analysis of spice samples has been shown to be an applicable method for the detection of all irradiated spices. It was established that the TL response originates from the adhering mineral dust in the sample. Definitive identification of many irradiated spices requires the separation of a mineral extract from the organic fraction of the spice sample. This separation can be achieved by using density centrifugation with a heavy liquid, sodium polytungstate. Clear discrimination between untreated and irradiated spice samples has been obtained by re-irradiation of the mineral extract after the first TL analysis with an absorbed dose of about 1 kGy (normalisation). The ratio of the first to second TL response was about one for irradiated samples and well below one for untreated samples. These methods have been investigated with a range of spices to establish the most suitable method for routine control purposes. (author)

  7. CARP: a computer code and albedo data library for use by BREESE, the MORSE albedo package

    International Nuclear Information System (INIS)

    Emmett, M.B.; Rhoades, W.A.

    1978-10-01

    The CARP computer code was written to allow processing of DOT angular flux tapes to produce albedo data for use in the MORSE computer code. An albedo data library was produced containing several materials. 3 tables

  8. Thermoluminescence dating of pleistocene sediments

    International Nuclear Information System (INIS)

    Poupeau, G.; Souza, J.H.; Rivera, A.

    1984-01-01

    After a short introduction on recent trends in quaternary geochronology, this article focuses on the thermoluminescence dating of sediments, whose principles and present limits and prospects are discussed. Results are presented for the TL behaviour of sands from various geological contexts in Brazil. They show that the coarse (approx. 100-200μm) quartz fraction of coastal and intra continental, eolian and fluvial-type deposits, might be datable by TL from the upper Holocene to at least the basis of the upper Pleistocene, with a precision of + - 10-15%. (Author) [pt

  9. Thermoluminescence dating of pleistocene sediments

    International Nuclear Information System (INIS)

    Poupeau, G.; Souza, J.H.

    1984-01-01

    After a short introduction on recent trends in quaternary geochronology, this article focuses on the thermoluminescence (TL) dating of sediments, whose principles, present limits and prospects are discussed. Results are presented for TL behavior of sands from various geological contexts in Brazil. They show that the coarse (approx. 100-200 μm) quartz fraction of coastal and intracontinental, eolian and fluvial - type deposits, might be datable by TL from the upper Holocene to at least the base of the upper Pleistocene, with a precision of +- 10-15%. (Author) [pt

  10. Thermoluminescence study of lithium fluorides

    CERN Document Server

    Abu-Alazm, S M

    2003-01-01

    The spectrum of the light emitted during thermoluminescence (TL) from irradiated lif sample with different doses of Xe, Kr and electrons have been studied. The results show a main peak for all samples irradiated and unirradiated at temperature about 200 degree C. Morcever when the reaches to the value 5x10 sup 1 1 ion/cm sup 2 a new two bands begin to appear in case of Xe and Kr ion irradiation. The TL spectra under Kr and Xe ion irradiation similar at the same dose. However, the spectra under electron irradiation were found to be rather different than under heavy ions irradiation.

  11. Models and methods in thermoluminescence

    International Nuclear Information System (INIS)

    Furetta, C.

    2005-01-01

    This work contains a conference that was treated about the principles of the luminescence phenomena, the mathematical treatment concerning the thermoluminescent emission of light as well as the Randall-Wilkins model, the Garlick-Gibson model, the Adirovitch model, the May-Partridge model, the Braunlich-Scharman model, the mixed first and second order kinetics, the methods for evaluating the kinetics parameters such as the initial rise method, the various heating rates method, the isothermal decay method and those methods based on the analysis of the glow curve shape. (Author)

  12. Recent research into thermoluminescent dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, T [National Inst. of Radiological Sciences, Chiba (Japan)

    1979-04-01

    The trend of basic research in thermoluminescent dosimetry (TLD), the results, and developing fields in which it can be applied are reported. This trend is outlined from the viewpoint fields of application, a new trend in TLD readers, the conditions of development of new photogenic substances, and research in the radiation characteristics of photogenic substances (radiosensitivity to particle rays and ultraviolet rays, dose rate dependence, temperature dependence at irradiation, and ..gamma.. ray energy dependence). Utilization of TLD in the medical field for measurement of environmental radiation and as a monitor for workers exposed to radiation is discussed. An international comparison of dose was necessary in order to prove its universal validity.

  13. Models and methods in thermoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Furetta, C. [ICN, UNAM, A.P. 70-543, Mexico D.F. (Mexico)

    2005-07-01

    This work contains a conference that was treated about the principles of the luminescence phenomena, the mathematical treatment concerning the thermoluminescent emission of light as well as the Randall-Wilkins model, the Garlick-Gibson model, the Adirovitch model, the May-Partridge model, the Braunlich-Scharman model, the mixed first and second order kinetics, the methods for evaluating the kinetics parameters such as the initial rise method, the various heating rates method, the isothermal decay method and those methods based on the analysis of the glow curve shape. (Author)

  14. Microcomputer-controlled thermoluminescent analyser IJS MR-200

    International Nuclear Information System (INIS)

    Mihelic, M.; Miklavzic, U.; Rupnik, Z.; Satalic, P.; Spreizer, F.; Zerovnik, I.

    1985-01-01

    Performances and concept of the multipurpose, microcomputer-controlled thermoluminescent analyser, designed for use in laboratory work TL dosemeters as well as for routine dose readings in the range from ecological to accident doses is described. The main features of the analyser are: time-linear sampling, digitalisation, storing, and subsequent displaying on the monitor time scale of the glow and and temperature curve of the TL material; digital stabilization, control and diagnostic of the analog unit; ability of storing 7 different 8-parametric heating programs; ability of storing 15 evaluation programs defined by 2 or 4 parameters and 3 different algorithms (altogether 5 types of evaluations). Analyser has several features intended for routine work: 9 function keys and possibilities of file forming on cassette or display disc, of dose calculation and averaging, of printing reports with names, and possibility of additional programming in Basic. (author)

  15. Empirical models of monthly and annual surface albedo in managed boreal forests of Norway

    Science.gov (United States)

    Bright, Ryan M.; Astrup, Rasmus; Strømman, Anders H.

    2013-04-01

    As forest management activities play an increasingly important role in climate change mitigation strategies of Nordic regions such as Norway, Sweden, and Finland -- the need for a more comprehensive understanding of the types and magnitude of biogeophysical climate effects and their various tradeoffs with the global carbon cycle becomes essential to avoid implementation of sub-optimal policy. Forest harvest in these regions reduces the albedo "masking effect" and impacts Earth's radiation budget in opposing ways to that of concomitant carbon cycle perturbations; thus, policies based solely on biogeochemical considerations in these regions risk being counterproductive. There is therefore a need to better understand how human disturbances (i.e., forest management activities) affect important biophysical factors like surface albedo. An 11-year remotely sensed surface albedo dataset coupled with stand-level forest management data for a variety of stands in Norway's most productive logging region are used to develop regression models describing temporal changes in monthly and annual forest albedo following clear-cut harvest disturbance events. Datasets are grouped by dominant tree species and site indices (productivity), and two alternate multiple regression models are developed and tested following a potential plus modifier approach. This resulted in an annual albedo model with statistically significant parameters that explains a large proportion of the observed variation, requiring as few as two predictor variables: i) average stand age - a canopy modifier predictor of albedo, and ii) stand elevation - a local climate predictor of a forest's potential albedo. The same model structure is used to derive monthly albedo models, with models for winter months generally found superior to summer models, and conifer models generally outperforming deciduous. We demonstrate how these statistical models can be applied to routine forest inventory data to predict the albedo

  16. Method for detecting radiation dose utilizing thermoluminescent material

    International Nuclear Information System (INIS)

    Miller, S.D.; McDonald, J.C.; Eichner, F.N.; Durham, J.S.

    1992-01-01

    The amount of ionizing radiation to which a thermoluminescent material has been exposed is determined by first cooling the thermoluminescent material and then optically stimulating the thermoluminescent material by exposure to light. Visible light emitted by the thermoluminescent material as it is allowed to warm up to room temperature is detected and counted. The thermoluminescent material may be annealed by exposure to ultraviolet light. 5 figs

  17. Calculation of double energy angle differential neutron albedos for radiation shielding applications

    International Nuclear Information System (INIS)

    Litaize, O.; Diop, C.M.; Nimal, J.C.

    2000-01-01

    Void radiation shielding problems can be dealt with albedo concept which is an alternative to the complex bringing into operation of the 'exact' transport method calculations (SN, Monte Carlo). Up to here, differential albedos are used for single reflections from walls in the NARCISSE-3 propagation albedo code developed at CEA and used for project calculations. For taking into account the neutron multiple reflections on lacunar medium walls, double energy-angle differential albedos are needed. TRIPOLI-4 neutral particle transport Monte Carlo code in three dimensional geometries, has been chosen to implement a double differential albedo calculus routine and therefore to generate albedo data for different kinds of medium. The surfacic estimator, which could be used, is not enough efficient because all neutrons do not contribute to the result. A new estimator is carried out. At each collision site, during the neutron history simulation, it allows to compute the probability of the neutron to go through the medium and to come through the reflection surface in the direction and at the energy considered. This estimator is about hundred times more efficient than the surfacic estimator. (author)

  18. Thermoluminescent dosimetry and assessment of personal dose

    International Nuclear Information System (INIS)

    Boas, J.F.; Martin, L.J.; Young, J.G.

    1982-01-01

    Thermoluminescence is discussed in terms of the energy band structure of a crystalline solid and the trapping of charge carriers by point defects. Some general properties of thermoluminescent materials used for dosimetry are outlined, with thermoluminescence of CaSO 4 :Dy being described in detail. The energy response function and the modification of the energy response of a dosimeter by shielding are discussed. The final section covers the connection between exposure, as recorded by a TLD badge, and the absorbed dose to various organs from gamma radiation in a uranium mine; the conversion from absorbed dose to dose equivalent; and uncertainties in assessment of dose equivalent

  19. Thermoluminescent Signals Caused by Disturbing Effects

    International Nuclear Information System (INIS)

    German, U.; Weinstein, M.; Ben-Shachar, B.

    1999-01-01

    One of the major sources of uncertainty in the measurement of low radiation doses by means of thermoluminescence dosemeters is the presence of disturbing thermoluminescence signals, especially luminescence caused by visible light, and by materials attached to the heated areas. Glow curves of thermoluminescence dosemeters contain useful information that can improve the accuracy and the reliability of the thermoluminescent measurements. The influence of the various disturbing effects can be recognised in the shape of the glow curves and can sometimes be separated from the exposure. Some examples are presented of signals arising from the two disturbing effects mentioned above, the signal contributed by Teflon used in the TLD-100 cards of Bicron/Harshaw and some abnormal glow curves due to dirt attached to the cards. Subtraction of the contributions due to these effects is suggested to obtain the net exposure signal. (author)

  20. Dose-rate dependence of thermoluminescence response

    International Nuclear Information System (INIS)

    McKeever, S.W.S.; Chen, R.; Groom, P.J.; Durrani, S.A.

    1980-01-01

    The previously observed dose-rate effect of thermoluminescence in quartz at high dose-rates is given at theoretical formulation. Computer calculations simulating the experimental conditions yield similar results to the experimental ones. (orig.)

  1. Study for correction of neutron scattering in the calibration of the albedo individual monitor from the Neutron Laboratory (LN), IRD/CNEN-RJ, Brazil

    International Nuclear Information System (INIS)

    Freitas, B.M.; Silva, A.X. da

    2014-01-01

    The Instituto de Radioprotecao e Dosimetria (IRD) runs a neutron individual monitoring service with albedo type monitor and thermoluminescent detectors (TLD). Moreover the largest number of workers exposed to neutrons in Brazil is exposed to 241 Am-Be fields. Therefore a study of the response of albedo dosemeter due to neutron scattering from 241 Am-Be source is important for a proper calibration. In this work, it has been evaluated the influence of the scattering correction in two distances at the Low Scattering Laboratory of the Neutron Laboratory of the Brazilian National Laboratory (Lab. Nacional de Metrologia Brasileira de Radiacoes Ionizantes) in the calibration of that albedo dosemeter for a 241 Am-Be source. (author)

  2. Personnel monitoring of radiations with thermoluminescent dosemeters

    International Nuclear Information System (INIS)

    Miano, S.C.

    1987-01-01

    The basics of personnel dosimetry technics, used by the Radiologic Protetion and Assessorie Service (SAPRA) are presented, consisting on use of thermoluminescent and CaSO 4 :Dy monitors in aggregated pellets by Teflon. The characteristics of this dosemeters, relating to the sensitivity, energetic dependence, spike temperature, characteristic emission curve, decay and light effect are shown. The thermoluminescent dosemeter measure system and the personnel monitoring system are also described. (C.G.C.) [pt

  3. Personal radiation monitoring with thermoluminescent dosemeters

    International Nuclear Information System (INIS)

    Miano, S.C.

    1987-01-01

    The technique of personal dosimetry used by SAPRA (Servico de Assessoria e Protecao Radiologica S/C Ltda., Brazil) is presented. Thermoluminescent monitors and CaSO 4 : Dy are used in pastilles united by teflon. Characteristics of the dosemeters are briefly reported. The system of thermoluminescent measurement, designed and constructed by SAPRA, and the system of personal monitoring are described. (M.A.C.) [pt

  4. Thermoluminescence of LaAlO3

    International Nuclear Information System (INIS)

    Morales H, A.; Zarate M, J.; Rivera M, T.; Azorin N, J.

    2015-10-01

    In this paper the thermoluminescent properties of doped lanthanum aluminate (LaAlO 3 ) with dysprosium ion (Dy) were studied. The thermoluminescence characteristics in the samples were obtained using an ultraviolet radiation of 220 nm. The LaAlO 3 :Dy samples were prepared by the modified Pechini method (Spray Dryer). The structural and morphological characterization was obtained by X-ray diffraction (XRD) and scanning electron microscopy (Sem) techniques respectively. The size particle composing the agglomerate was determined by Sem, agglomerated particles composed size of 2μm were observed. The thermoluminescence response of LaAlO 3 :Dy was compared with that obtained with the undoped sample. Thermoluminescence brightness curves of LaAlO 3 :Dy showed a peak centered at 185 grades C. Sensitivity of doped sample was greater, about 100 times compared with the undoped sample. Thermoluminescence response in function of the wavelength showed a maximum at 220 nm. Also the fading in thermoluminescence response was studied. (Author)

  5. New laser technique revives old ideas for thermoluminescence neutron dosimetry

    International Nuclear Information System (INIS)

    Braeunlich, P.; Brown, M.; Gasiot, J.; Fillard, J.P.

    1982-01-01

    Laser heating is discussed as a means to evaluate thermoluminescence dosimeters in neutron dosimetry. Direct energy coupling from the photon beam to the phonons of the TL material permits heating of thin layers with rates of temperature increase exceeding 10 4 Ks - 1 . Rapid TLD evaluation will allow the design of dosimetry badges containing a number of different small thin film TLD elements in various orientations and behind appropriate filters, hydrogenous radiators, etc. Desired redundance is readily possible by using back-up TLDs for every specific task. Reading occurs with a scanning laser beam rather than by mechanically manipulating the TLD toward a fixed heat source. Improvements in the signal-to-noise ratio of up to a factor of 1000 are readily obtained. Thus, sensitive thin-film TLDs can be designed with negligible self-shielding for thermal neutrons in albedo applications and with known, nearly energy dependent cavity correction factors for dosimetry in mixed n-#betta# fields. Due to the greatly increased sensitivity possible with fast laser heating, significant advances are expected in the fast neutron dosimetry techniques which are based on hydrogeneous proton radiators or LET-dependent slow peak formation

  6. Intelligent Routines

    CERN Document Server

    Anastassiou, George A

    “Intelligent Routines II: Solving Linear Algebra and Differential Geometry with Sage” contains numerous of examples and problems as well as many unsolved problems. This book extensively applies the successful software Sage, which can be found free online http://www.sagemath.org/. Sage is a recent and popular software for mathematical computation, available freely and simple to use. This book is useful to all applied scientists in mathematics, statistics and engineering, as well for late undergraduate and graduate students of above subjects. It is the first such book in solving symbolically with Sage problems in Linear Algebra and Differential Geometry. Plenty of SAGE applications are given at each step of the exposition.

  7. Response of TLD-albedo and nuclear track dosimeters exposed to plutonium sources

    International Nuclear Information System (INIS)

    Brackenbush, L.W.; Baumgartner, W.V.; Fix, J.J.

    1991-12-01

    Neutron dosimetry has been extensively studied at Hanford since the mid-1940s. At the present time, Hanford contractors use thermoluminescent dosimeter (TLD)-albedo dosimeters to record the neutron dose equivalent received by workers. The energy dependence of the TLD-albedo dosimeter has been recognized and documented since introduced at Hanford in 1964 and numerous studies have helped assure the accuracy of dosimeters. With the recent change in Hanford's mission, there has been a significant decrease in the handling of plutonium tetrafluoride, and an increase in the handling of plutonium metal and plutonium oxide sources. This study was initiated to document the performance of the current Hanford TLD-albedo dosimeter under the low scatter conditions of the calibration laboratory and under the high scatter conditions in the work place under carefully controlled conditions at the Plutonium Finishing Plant (PFP). The neutron fields at the PFP facility were measured using a variety of instruments, including a multisphere spectrometer, tissue equivalent proportional counters, and specially calibrated rem meters. Various algorithms were used to evaluate the TLD-albedo dosimeters, and the results are given in this report. Using current algorithms, the dose equivalents evaluated for bare sources and sources with less than 2.5 cm (1 in.) of acrylic plastic shielding in high scatter conditions typical of glove box operations are reasonably accurate. Recently developed CR-39 track etch dosimeters (TEDs) were also exposed in the calibration laboratory and at the PFP. The results indicate that the TED dosimeters are quite accurate for both bare and moderated neutron sources. Until personnel dosimeter is available that incorporates a direct measure of the neutron dose to a person, technical uncertainties in the accuracy of the recorded data will continue

  8. Response of TLD-albedo and nuclear track dosimeters exposed to plutonium sources

    Energy Technology Data Exchange (ETDEWEB)

    Brackenbush, L.W.; Baumgartner, W.V.; Fix, J.J.

    1991-12-01

    Neutron dosimetry has been extensively studied at Hanford since the mid-1940s. At the present time, Hanford contractors use thermoluminescent dosimeter (TLD)-albedo dosimeters to record the neutron dose equivalent received by workers. The energy dependence of the TLD-albedo dosimeter has been recognized and documented since introduced at Hanford in 1964 and numerous studies have helped assure the accuracy of dosimeters. With the recent change in Hanford`s mission, there has been a significant decrease in the handling of plutonium tetrafluoride, and an increase in the handling of plutonium metal and plutonium oxide sources. This study was initiated to document the performance of the current Hanford TLD-albedo dosimeter under the low scatter conditions of the calibration laboratory and under the high scatter conditions in the work place under carefully controlled conditions at the Plutonium Finishing Plant (PFP). The neutron fields at the PFP facility were measured using a variety of instruments, including a multisphere spectrometer, tissue equivalent proportional counters, and specially calibrated rem meters. Various algorithms were used to evaluate the TLD-albedo dosimeters, and the results are given in this report. Using current algorithms, the dose equivalents evaluated for bare sources and sources with less than 2.5 cm (1 in.) of acrylic plastic shielding in high scatter conditions typical of glove box operations are reasonably accurate. Recently developed CR-39 track etch dosimeters (TEDs) were also exposed in the calibration laboratory and at the PFP. The results indicate that the TED dosimeters are quite accurate for both bare and moderated neutron sources. Until personnel dosimeter is available that incorporates a direct measure of the neutron dose to a person, technical uncertainties in the accuracy of the recorded data will continue.

  9. Response of TLD-albedo and nuclear track dosimeters exposed to plutonium sources

    Energy Technology Data Exchange (ETDEWEB)

    Brackenbush, L.W.; Baumgartner, W.V.; Fix, J.J.

    1991-12-01

    Neutron dosimetry has been extensively studied at Hanford since the mid-1940s. At the present time, Hanford contractors use thermoluminescent dosimeter (TLD)-albedo dosimeters to record the neutron dose equivalent received by workers. The energy dependence of the TLD-albedo dosimeter has been recognized and documented since introduced at Hanford in 1964 and numerous studies have helped assure the accuracy of dosimeters. With the recent change in Hanford's mission, there has been a significant decrease in the handling of plutonium tetrafluoride, and an increase in the handling of plutonium metal and plutonium oxide sources. This study was initiated to document the performance of the current Hanford TLD-albedo dosimeter under the low scatter conditions of the calibration laboratory and under the high scatter conditions in the work place under carefully controlled conditions at the Plutonium Finishing Plant (PFP). The neutron fields at the PFP facility were measured using a variety of instruments, including a multisphere spectrometer, tissue equivalent proportional counters, and specially calibrated rem meters. Various algorithms were used to evaluate the TLD-albedo dosimeters, and the results are given in this report. Using current algorithms, the dose equivalents evaluated for bare sources and sources with less than 2.5 cm (1 in.) of acrylic plastic shielding in high scatter conditions typical of glove box operations are reasonably accurate. Recently developed CR-39 track etch dosimeters (TEDs) were also exposed in the calibration laboratory and at the PFP. The results indicate that the TED dosimeters are quite accurate for both bare and moderated neutron sources. Until personnel dosimeter is available that incorporates a direct measure of the neutron dose to a person, technical uncertainties in the accuracy of the recorded data will continue.

  10. UV/visible albedos from airborne measurements

    Science.gov (United States)

    Webb, A.; Kylling, A.; Stromberg, I.

    2003-04-01

    During the INSPECTRO campaign effective surface albedo was measured at UV and visible wavelengths from two airborne platforms, a Cessna light aircraft and a hot air balloon. On board the Cessna was a scanning spectroradiometer measuring from 300 - 500nm at 10nm intervals. The NILU cube, with 6 faces and two UV channels at 312 and 340nm, was suspended beneath the hot air balloon. Flights took place over East Anglia during September, 2002. Balloon flights were made below cloud layers, while the Cessna flew both above and below cloud. The Cessna also flew over Barton Bendish, where surface albedos have been measured for ground truthing of satellite data, and measured the effective albedo at four visible wave- lengths in the centres of the satellite bandpass functions. Results of measurements from the different platforms are compared, and model simulations used to deduce the surface albedo from the effective albedo at altitude, giving, for example, an albedo of 0.02 ± 0.01 at 340nm.

  11. Recent advances in thermoluminescence dating

    International Nuclear Information System (INIS)

    Aitken, M.J.

    1984-01-01

    Initially the application of thermoluminescent dating was to ancient pottery and other baked clay, the detection of forgeries in art ceramics having a particularly powerful impact. In recent years there has been a growing extension of TL into non-pottery materials. Heated flints from paleolithic fire-places is one application. Another is in the dating of igneous rocks from recent volcanic events; formerly this had been impossible on account of the malign phenomenon of non-thermal ('anomalous') fading exhibited by volcanic minerals but this is now being circumvented by utilising TL in the 600 0 C region of the glow curve. TL dating has also been extended to unburnt calcite, one application being stalagmitic floors in paleolithic caves. Another recent development is the use of TL for dating aeolian sediment and some types of waterborne sediment. These developments give prospect of establishing a TL-based chronology, both for archaeology and quaternary research, extending back well beyond the range of radiocarbon, perhaps reaching a million years ago. (author)

  12. The MODIS (Collection V005) BRDF/albedo product: Assessment of spatial representativeness over forested landscapes

    Energy Technology Data Exchange (ETDEWEB)

    Roman, Miguel O. [NASA Goddard Space Flight Center; Schaaf, Crystal [Boston University; Woodcock, Curtis E. [Boston University; Strahler, Alan [Boston University; Yang, Xiaoyuan [Boston University; Braswell, Rob H. [Complex Systems Research Center, Durham, NH; Curtis, Peter [Ohio State University, The, Columbus; Davis, Kenneth J. [Pennsylvania State University; Dragoni, Danilo [Indiana University; Goulden, Michael L. [University of California, Irvine; Gu, Lianhong [ORNL; Hollinger, David Y [ORNL; Meyers, Tilden P. [NOAA, Oak Ridge, TN; Wilson, Tim B. [NOAA; Munger, J. William [Harvard University; Wofsy, Steve [Harvard University; Privette, Jeffrey L. [NOAA; Richardson, Andrew D. [Harvard University

    2009-11-01

    A new methodology for establishing the spatial representativeness of tower albedo measurements that are routinely used in validation of satellite retrievals from global land surface albedo and reflectance anisotropy products is presented. This method brings together knowledge of the intrinsic biophysical properties of a measurement site, and the surrounding landscape to produce a number of geostatistical attributes that describe the overall variability, spatial extent, strength of the spatial correlation, and spatial structure of surface albedo patterns at separate seasonal periods throughout the year. Variogram functions extracted from Enhanced Thematic Mapper Plus (ETM+) retrievals of surface albedo using multiple spatial and temporal thresholds were used to assess the degree to which a given point (tower) measurement is able to capture the intrinsic variability of the immediate landscape extending to a satellite pixel. A validation scheme was implemented over a wide range of forested landscapes, looking at both deciduous and coniferous sites, from tropical to boreal ecosystems. The experiment focused on comparisons between tower measurements of surface albedo acquired at local solar noon and matching retrievals from the MODerate Resolution Imaging Spectroradiometer (MODIS) (Collection V005) Bidirectional Reflectance Distribution Function (BRDF)/albedo algorithm. Assessments over a select group of field stations with comparable landscape features and daily retrieval scenarios further demonstrate the ability of this technique to identify measurement sites that contain the intrinsic spatial and seasonal features of surface albedo over sufficiently large enough footprints for use in modeling and remote sensing studies. This approach, therefore, improves our understanding of product uncertainty both in terms of the representativeness of the field data and its relationship to the larger satellite pixel.

  13. Arctic sea ice albedo from AVHRR

    Science.gov (United States)

    Lindsay, R. W.; Rothrock, D. A.

    1994-01-01

    The seasonal cycle of surface albedo of sea ice in the Arctic is estimated from measurements made with the Advanced Very High Resolution Radiometer (AVHRR) on the polar-orbiting satellites NOAA-10 and NOAA-11. The albedos of 145 200-km-square cells are analyzed. The cells are from March through September 1989 and include only those for which the sun is more than 10 deg above the horizon. Cloud masking is performed manually. Corrections are applied for instrument calibration, nonisotropic reflection, atmospheric interference, narrowband to broadband conversion, and normalization to a common solar zenith angle. The estimated albedos are relative, with the instrument gain set to give an albedo of 0.80 for ice floes in March and April. The mean values for the cloud-free portions of individual cells range from 0.18 to 0.91. Monthly averages of cells in the central Arctic range from 0.76 in April to 0.47 in August. The monthly averages of the within-cell standard deviations in the central Arctic are 0.04 in April and 0.06 in September. The surface albedo and surface temperature are correlated most strongly in March (R = -0.77) with little correlation in the summer. The monthly average lead fraction is determined from the mean potential open water, a scaled representation of the temperature or albedo between 0.0 (for ice) and 1.0 (for water); in the central Arctic it rises from an average 0.025 in the spring to 0.06 in September. Sparse data on aerosols, ozone, and water vapor in the atmospheric column contribute uncertainties to instantaneous, area-average albedos of 0.13, 0.04, and 0.08. Uncertainties in monthly average albedos are not this large. Contemporaneous estimation of these variables could reduce the uncertainty in the estimated albedo considerably. The poor calibration of AVHRR channels 1 and 2 is another large impediment to making accurate albedo estimates.

  14. CaSO4: Dy + Teflon thermoluminescent dosemeters

    International Nuclear Information System (INIS)

    Campos, L.L.

    1986-01-01

    A pellet dosemeter of CaSO 4 : Dy + Teflon was developed at IPEN. CaSO 4 : Dy thermoluminescent phosphor, grown in the Dosimetric Materials Production Laboratory was chosen, due to its high sensitivity, ease of preparation and comparatively low cost. Pellets were produced by cold pressing and sintering a mixture of CaSO 4 : Dy and Teflon powders. Extensive work was done to study in detail all CaSO 4 : Dy pellets characteristics from the point of view of dosimetry with the purpose of introducing it in the routine use. A filter combination providing an energy independent response from 20 KeV to 1,25 MeV was obtained. The dosemeter consists of three pellets sealed between two thin plastic sheets and placed under plastic and lead filters. The combination of these tree filters allows the exposure as well as the energy determination of an unknown source. (Author) [pt

  15. New thermoluminescence techniques for mineral exploration

    International Nuclear Information System (INIS)

    Levy, P.W.; Holmes, R.J.; Ypma, P.J.; Chen, C.C.; Swiderski, H.S.

    1977-01-01

    The thermoluminescence of carbonate host rock in the vicinity of known lead-zinc and lead-zinc-fluorite mineralization was reexamined for possible development as an exploration technique. The measurements were made with equipment for determining the thermoluminescence spectrum at closely spaced temperature intervals. Radiation-induced thermoluminescence was also measured. Samples were studied from five localities in Mexico, Southwest Africa, and the United States. Four thermoluminescence properties were found to vary with ''distance-from-ore'' in a systematic manner. These include the glow peak intensity and temperature and the emission spectrum peak energy and full width at half-maximum. For example, in both limestone and dolomite, the high-temperature glow peak intensities are low or negligible within the ore and as the distance from the contact increases the intensity rises rapidly to a maximum, or maxima, and then decreases irregularly to constant value slightly above that in the ore. Depending on the thickness of the ore, the thermoluminescence characteristics associated with the mineralization extended from ten to a hundred or so meters from the ore host rock contact. 5 figures

  16. Influence of stratospheric aerosol on albedo

    Energy Technology Data Exchange (ETDEWEB)

    Gormatyuk, Yu K; Kaufman, Yu G; Kolomeev, M P

    1985-06-01

    The influence of stratospheric aerosol (SA) on the transfer of solar radiation in the atmosphere is the principal factor determining the effect of SA on climate. The change in the radiation balance under the influence of SA is computed most precisely in radiative-convective models. However, the complex method used in these models cannot be used for other types of climate models. The objective of the study was to obtain a quantitative evaluation of the influence of SA on albedo without the use of simplifying assumptions. In the approximation of single scattering an expression is derived for change in albedo under the influence of stratospheric aerosol taking into account the dependence of albedo of the atmosphere-earth's surface system on solar zenith distance. The authors give the results of computations of the response of mean annual albedo to sulfuric acid aerosol for 10/sup 0/ latitude zones in the Northern Hemisphere. Specifically, computations of the optical characteristics of aerosol were made using the Mie theory for 10 spectral intervals taking in the range of wavelengths of solar radiation from 0.29 to 4.0 ..mu.. m. The refractive index of aerosol was stipulated in accordance with Palmer and Williams. The angular dependence of albedo for cloudless and cloudy atmospheres given by Harshvardhan was used. The values of undisturbed albedo were assumed to be identical for all wavelengths due to lack of climatological data on the spectral dependence of albedo of the atmosphere-earth's surface system. The angular distribution of the intensity of solar radiation for each of the latitude zones was computed by the method described by I.M. Alekseyev, et al.

  17. SURFACE ALBEDO AND SPECTRAL VARIABILITY OF CERES

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian-Yang; Reddy, Vishnu; Corre, Lucille Le; Sykes, Mark V.; Prettyman, Thomas H. [Planetary Science Institute, 1700 E. Ft. Lowell Road, Suite 106, Tucson, AZ 85719 (United States); Nathues, Andreas; Hoffmann, Martin; Schaefer, Michael [Max Planck Institute for Solar System Research, Göttingen (Germany); Izawa, Matthew R. M.; Cloutis, Edward A. [University of Winnipeg, Winnipeg, Manitoba (Canada); Carsenty, Uri; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Schröder, Stefan E. [German Aerospace Center (DLR), Institute of Planetary Research, Berlin (Germany); Castillo-Rogez, Julie C. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Schenk, Paul [Lunar and Planetary Institute, Houston, TX 77058 (United States); Williams, David A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Smith, David E. [Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Zuber, Maria T. [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); and others

    2016-02-01

    Previous observations suggested that Ceres has active, but possibly sporadic, water outgassing as well as possibly varying spectral characteristics over a timescale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, as well as the newly acquired images by the Dawn  Framing Camera, to search for spectral and albedo variability on Ceres, on both a global scale and in local regions, particularly the bright spots inside the Occator crater, over timescales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in the Occator crater by >15%, or the global albedo by >3% over the various timescales that we searched. Recently reported spectral slope variations can be explained by changing Sun–Ceres–Earth geometry. The active area on Ceres is less than 1 km{sup 2}, too small to cause global albedo and spectral variations detectable in our data. Impact ejecta due to impacting projectiles of tens of meters in size like those known to cause observable changes to the surface albedo on Asteroid Scheila cannot cause detectable albedo change on Ceres due to its relatively large size and strong gravity. The water vapor activity on Ceres is independent of Ceres’ heliocentric distance, ruling out the possibility of the comet-like sublimation process as a possible mechanism driving the activity.

  18. Sea ice-albedo climate feedback mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, J.L.; Curry, J.A. [Univ. of Colorado, Boulder, CO (United States); Ebert, E.E. [Bureau of Meterology Research Center, Melbourne (Australia)

    1995-02-01

    The sea ice-albedo feedback mechanism over the Arctic Ocean multiyear sea ice is investigated by conducting a series of experiments using several one-dimensional models of the coupled sea ice-atmosphere system. In its simplest form, ice-albedo feedback is thought to be associated with a decrease in the areal cover of snow and ice and a corresponding increase in the surface temperature, further decreasing the area cover of snow and ice. It is shown that the sea ice-albedo feedback can operate even in multiyear pack ice, without the disappearance of this ice, associated with internal processes occurring within the multiyear ice pack (e.g., duration of the snow cover, ice thickness, ice distribution, lead fraction, and melt pond characteristics). The strength of the ice-albedo feedback mechanism is compared for several different thermodynamic sea ice models: a new model that includes ice thickness distribution., the Ebert and Curry model, the Mayjut and Untersteiner model, and the Semtner level-3 and level-0 models. The climate forcing is chosen to be a perturbation of the surface heat flux, and cloud and water vapor feedbacks are inoperative so that the effects of the sea ice-albedo feedback mechanism can be isolated. The inclusion of melt ponds significantly strengthens the ice-albedo feedback, while the ice thickness distribution decreases the strength of the modeled sea ice-albedo feedback. It is emphasized that accurately modeling present-day sea ice thickness is not adequate for a sea ice parameterization; the correct physical processes must be included so that the sea ice parameterization yields correct sensitivities to external forcing. 22 refs., 6 figs., 1 tab.

  19. Characteristic of 120 degree C thermoluminescence peak of iceland spar

    International Nuclear Information System (INIS)

    Lu Xinwei; Han Jia

    2006-01-01

    The basic characteristic of 120 degree C thermoluminescence peak of iceland spar was studied. The experimental result indicates the longevity of 120 degree C thermoluminescence peak of iceland spar is about 2 h under 30 degree C. The thermoluminescence peak moves to the high temperature when the heating speed increasing. The intensity of 120 degree C thermoluminescence peak of iceland spar is directly proportional to radiation dose under 15 Gy. (authors)

  20. Thermal neutron albedo measurements for multilithic reflectors

    International Nuclear Information System (INIS)

    Mehboob, Khurram; Ahmed, Raheel; Ali, Majid; Tabassam, Uzma

    2013-01-01

    Highlights: • Measurement of thermal neuron albedo for multilithic reflectors. • Modeling of experiments in MATLAB. • Comparison of numerical calculated and experimental values. • Study of thermal neutron albedo in different multilayered shielding. - Abstract: An experimental measurement of the thermal neutron (0.025 eV) albedo (αth) has been carried out for multilithic shielding by using Am–Be neutron source and BF 3 detector. The measured saturation value for the thermal albedo of paraffin wax has been found to be 0.734 ± 0.020, which is in close agreement to the corresponding value 0.83 quoted in the literature. The thermal neutron albedo has been measured for the multilayered shielding in copper–wood, copper–aluminum, wood–paraffin and paraffin–iron combinations in horizontal geometric configurations. Modeling and numerical simulation have been carried out by developing a MATLAB code which solves the diffusion equation in order to calculate the experimental results. Good agreement has been found between the numerical calculated and experimental results. The uncertainties in the measurements have also been calculated based on error propagation of the underlying Poisson distribution

  1. Work place monitoring in accelerator facilities using thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    Ribeiro, M.S.; Sanches, M.P.; Osima, A.M.; Rodriguez, D.L.; Carvalho, R.N.; Somessari, R.N.

    1998-01-01

    The increase in the use of large amounts of energy and large particles accelerators in development or in industrial processes for the reticulation, polymerization and sterilization of cables and wires allowed to discover and monitor work places in facilities having particle accelerators at the Institute of Energy and Nuclear Inquiries Comissao National de Energy Nuclear. Measures previously taken by technicians in routine monitoring, show that radiation doses found in the beams tube and at the door of the accelerator area is high enough to require routine programs to monitor work places at the installation. That is why, fifteen thermoluminescent dosimeters (TLD) where placed in different points of the facility where doses must be measured along a three month period and at the same time readings must be taken from control dosimeters kept within a shielded container. The monitor had a small double layer with three pellets of TLD CaSO4 Dy inside of a route carrier adopted in routine workers dosimetry usually. Outcomes show that the radiological protection program must be implemented to ameliorate and guarantee safety procedures

  2. Development of thermoluminescence dating techniques at Oxford

    International Nuclear Information System (INIS)

    Fleming, S.J.

    1977-01-01

    The two-decade long history of thermoluminescene as a pottery dating method is surveyed with particular reference to the various problems that have been encountered in the Oxford Laboratory's research programme. Effects, such as supralinearity and radon emanation, are explained in terms of how they are measured and how their existence influences thermoluminescence (TL) dating accuracy (currently close to plus minus 7% per analysis). Illustrations of Thermoluminescence (TL) applications include a Nok culture terracotta from Nigeria and a Cambodia bronze Buddha figure of the Khmer period, dated ising the ceramic-like casting-core retained within it. (author)

  3. Thermoluminescence: Potential Applications in Forensic Science

    Science.gov (United States)

    Ingham, J. D.; Lawson, D. D.

    1973-01-01

    In crime laboratories one of the most difficult operations is to determine unequivocally whether or not two samples of evidence of the same type were originally part of the same thing or were from the same source. It has been found that high temperature thermoluminescence (room temperature to 723 K) can be used for comparisons of this type, although work to date indicates that there is generally a finite probability for coincidental matching of glass or soil samples. Further work is required to determine and attempt to minimize these probabilities for different types of materials, and to define more clearly the scope of applicability of thermoluminescence to actual forensic situations.

  4. Annual radiation dose in thermoluminescence dating

    International Nuclear Information System (INIS)

    Li Huhou

    1988-01-01

    The annual radiation dose in thermoluminescence dating has been discussed. The autor gives an entirely new concept of the enviromental radiation in the thermoluminescence dating. Methods of annual dose detemination used by author are dating. Methods of annual dose determination used by author are summed up, and the results of different methods are compared. The emanium escapiug of three radioactive decay serieses in nature has been considered, and several determination methods are described. The contribution of cosmic rays for the annual radiation dose has been mentioned

  5. Annual radiation dose in thermoluminescence dating

    Energy Technology Data Exchange (ETDEWEB)

    Huhou, Li [Chinese Academy of Social Sciences, Beijing, BJ (China). Inst. of Archaeology

    1988-11-01

    The annual radiation dose in thermoluminescence dating has been discussed. The autor gives an entirely new concept of the enviromental radiation in the thermoluminescence dating. Methods of annual dose detemination used by author are dating. Methods of annual dose determination used by author are summed up, and the results of different methods are compared. The emanium escapiug of three radioactive decay serieses in nature has been considered, and several determination methods are described. The contribution of cosmic rays for the annual radiation dose has been mentioned.

  6. Intercomparison measurements with albedo neutron dosimeters

    International Nuclear Information System (INIS)

    Alberts, W.G.; Kluge, H.

    1994-01-01

    Since the introduction of the albedo dosimeter as the official personal neutron dosimeter the dosimetry services concerned have participated in intercomparison measurements at the PTB. Their albedo dosimeters were irradiated in reference fields produced by unmoderated and D 2 O-moderated 252 Cf neutron sources in the standard irradiation facility of the PTB. Six fields with fluences different in energy and angle distribution could be realised in order to determine the response of the albedo dosimeter. The dose equivalent values evaluated by the services were compared with the reference values of the PTB for the directional dose equivalent H'(10). The results turned out to be essentially dependent on the evaluation method and the choice of the calibration factors. (orig.) [de

  7. Routine Responses to Disruption of Routines

    Science.gov (United States)

    Guha, Mahua

    2015-01-01

    "Organisational routines" is a widely studied research area. However, there is a dearth of research on disruption of routines. The few studies on disruption of routines discussed problem-solving activities that are carried out in response to disruption. In contrast, this study develops a theory of "solution routines" that are a…

  8. In vivo dosimetry using thermoluminescent detector in cancer therapy of head and neck

    International Nuclear Information System (INIS)

    Viegas, Claudio C.B.; Batista, D.V.; Campos, A.M.; Lopes, R.T.

    2002-01-01

    The viability and implementation of a routine in vivo dosimetry, using thermoluminescent dosemeters (TLD), at the radiotherapy section of the National Institute of Cancer in Brazil, in the case of head and neck treatment is shown. In order to reach that aim, the characteristics of the response of the LiF:Mg;Ti (TLD-100) thermoluminescent detectors in powder form were determined. The performed of this detector for in vivo dosimetry was testes using an RANDO Alderson anthropomorphic phantom and, once their adequability proved for the kind of measurements proposed , it was used for dose assessment in the case of tumour treatments in the head and neck regions, for Cobalt-60 irradiations. (author)

  9. Photoluminescence, trap states and thermoluminescence decay ...

    Indian Academy of Sciences (India)

    Administrator

    Photoluminescence, trap states and thermoluminescence decay process study of Ca2MgSi2O7 : Eu. 2+. , Dy. 3+ phosphor. RAVI SHRIVASTAVA*, JAGJEET KAUR, VIKAS DUBEY and BEENA JAYKUMAR. Govt. VYT PG Autonomous College, Durg 491 001, (C.G.) India. MS received 9 July 2013; revised 5 December 2013.

  10. Thermoluminescence in some copper-doped compounds

    International Nuclear Information System (INIS)

    Patil, R.R.; Moharil, S.V.; Dhopte, S.M.; Muthal, P.L.; Kondawar, V.K.

    2003-01-01

    Thermoluminescence (TL) in various Cu + -doped materials is studied. A good correlation between the presence of copper in the Cu + form and TL sensitivity is observed. Correlation between TL emission spectra and photoluminescence suggests that Cu + acts as the emission center in the TL process. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Rare earth oxyhalogenide base thermoluminescent material

    International Nuclear Information System (INIS)

    Rabatin, J.G.

    1976-01-01

    A process is described that consists to expose a thermoluminescent material to ionizing radiations, the material being a rare earth oxyhalogenide with terbium additions, to heat this material up to the emission of visible radiations and to measure the emitted radiations which are proportional to the ionizing radiation dose [fr

  12. Thermoluminescence dosimeters with narrow bandpass filters

    Science.gov (United States)

    Walker, Scottie W.

    2004-07-20

    A dosimetry method exposes more than one thermoluminescence crystals to radiation without using conventional filters, and reads the energy stored in the crystals by converting the energy to light in a conventional manner, and then filters each crystal output in a different portion of the spectrum generated by the crystals.

  13. Thermoluminescence of meteorites and their orbits

    Science.gov (United States)

    Melcher, C. L.

    1981-01-01

    The thermoluminescence levels of 45 ordinary chondrites are measured in order to provide information on the orbital characteristics of the meteorites before impact. Glow curves of the photon emission response of powdered samples of the meteorites to temperatures up to 550 C in the natural state and following irradiation by a laboratory test dose of 110,000 rad were obtained as functions of terrestrial age and compared to those of samples of the Pribram, Lost City and Innisfree meteorites, for which accurate orbital data is available. The thermoluminescence levels in 40 out of 42 meteorites are found to be similar to those of the three control samples, indicating that the vast majority of ordinary chondrites that survive atmospheric entry have perihelia in the range 0.8-1 AU. Of the remaining two, Farmville is observed to exhibit an unusually large gradient in thermoluminescence levels with sample depth, which may be a result of a temperature gradient arising in a slowly rotating meteorite. Finally, the thermoluminescence measured in the Malakal meteorite is found to be two orders of magnitude lower than control samples, which is best explained by thermal draining by solar heating in an orbit with a perihelion distance of 0.5 to 0.6 AU.

  14. Quality control of thermoluminesce personal dose monitoring

    International Nuclear Information System (INIS)

    Shang Aiguo; He Wenchang; Zhao Fengtao

    2006-01-01

    In order to evaluate the influence factor to thermoluminesce personal dose monitoring result, the every question that can appear based on the fact was analyzed. The results show that the detector, annealing, measuring process can influence the monitoring result. It gives some measures to enhance monitoring quality. (authors)

  15. Albedos of Jovian Trojans, Hildas and Centaurs

    Science.gov (United States)

    Romanishin, William; Tegler, Stephen C.

    2017-10-01

    We present distributions of optical V band albedos for samples of outer solar system minor bodies including Centaurs, Jovian Trojans and Hildas. Diameters come almost entirely from the NEOWISE catalog (Mainzer etal 2016- Planetary Data System). Optical photometry (H values) for about 2/3 of the approximately 2700 objects studied are from PanStarrrs (Veres et al 2015 Icarus 261, 34). The PanStarrs optical photometry is supplemented by H values from JPL Horizons (corrected to be on the same photometric system as the PanStarrs data) for the objects in the NEOWISE catalog that are not in the PanStarrs catalog. We compare the albedo distributions of various pairs of subsamples using the nonparametric Wilcoxon rank sum test. Examples of potentially interesting comparisons include: (1) The Hildas are 15-25% darker than the Trojans at a very high level of statistical significance. If the Hildas and Trojans started out with similar surfaces, the Hildas may have darkened due to the effects of gardening as they pass through zone III of the asteroid belt. (2) The median albedo of the gray Centaurs lies between that of the L4 and L5 Trojan groups (3) The median L5 Trojan cloud albedo is about 10% darker than that of the L4 cloud at a high level of significance. However, the modes of the L4 and L5 albedo distributions are very similar, perhaps indicating the presence of a distinct brighter component in the L4 cloud that is not found in the L5 cloud.

  16. Factors affecting polyamide prototypes design of Albedo dosemeters

    International Nuclear Information System (INIS)

    Martins, M.M.; Mauricio, C.L.P.; Fonseca, E.S.

    1996-01-01

    This work studies the most important factors which affect the response of albedo neutron dosemeters containing LiF TLDs with the aim to improve their sensitivity. It includes tests of thickness and shape of the polyamide moderator body prototypes, albedo window diameter and TLD position inside the moderator. Analyzing the results, an albedo neutron dosemeter prototype, B 4 C covered, was developed. The prototype has a response three times higher than the albedo dosemeter now in use in Brazil. (author)

  17. Comparison of neutron dose measured by Albedo TLD and etched tracks detector at PNC plutonium fuel facilities

    International Nuclear Information System (INIS)

    Tsujimura, N.; Momose, T.; Shinohara, K.; Ishiguro, H.

    1996-01-01

    Power Reactor and Nuclear Fuel Development Corporation (PNC) has fabricated Plutonium and Uranium Mixed OXide (MOX) fuel for FBR MONJU at Tokai works. In this site, PNC/Panasonic albedo TLDs/1/ are used for personnel neutron monitoring. And a part of workers wore Etched Tracks Detector (ETD) combined with TLD in order to check the accuracy of the neutron dose estimated by albedo TLD. In this paper, the neutron dose measured by TLD and ETD in the routine monitoring is compared at PNC plutonium fuel facilities. (author)

  18. Thermoluminescence dosemeter for personal dose equivalent assessment

    International Nuclear Information System (INIS)

    Silva, T.A. da; Rosa, L.A.R. da; Campos, L.L.

    1995-01-01

    The possibility was investigated of utilising a Brazilian thermoluminescence individual dosemeter, usually calibrated in terms of photon dose equivalent, for the assessment of the personal dose equivalent, H p (d), at depths of 0.07 and 10 mm. The dosemeter uses four CaSO 4 :Dy thermoluminescent detectors, between different filters, as the sensitive materials. It was calibrated in gamma and X radiation fields in the energy range from 17 to 1250 keV. Linear combinations of the responses of three detectors, in this energy range, allow the evaluation of H p (0.07) and H p (10), for radiation incidence angles varying from 0 to 60 degrees, with an accuracy better than 35%. The method is not applicable to mixed photon-beta fields. (author)

  19. Thermoluminescence dosimetry in Northwest Puerto Rico

    International Nuclear Information System (INIS)

    Block, A.M.; Clements, R.G.; Rosa, L.I.; Santos, F.

    1975-01-01

    In October, 1973, the Puerto Rico Water Resources Authority sought the initiation of studies aimed at determining background radiological characteristics of the northwestern quadrant of Puerto Rico using thermoluminescent dosemeters. Some of the studies were required for supporting data for the environmental report submitted as part of the licensing procedure in the establishment of thermonuclear electric power generation facilities in Barrio Islote, Arecibo, Puerto Rico. Previous studies of radiological characteristics of the area had been made using sodium iodide sensing equipment in an airplane flying at an altitude of 500 ft. The results are expressed in counts per second, and provide useful comparative levels for radioactivity measured with the thermoluminescent detectors. (U.S.)

  20. Albedo distribution in Lutzow-Holm Bay and its neighborhood

    Directory of Open Access Journals (Sweden)

    Kiyotaka Nakagawa

    1997-03-01

    Full Text Available A method has been developed for estimating the filtered narrow band surface albedo with NOAA/AVHRR data, and has been applied to analysis of the surface albedo distribution in Lutzow-Holm Bay and its neighborhood, Antarctica, in 1990. As a result, 16 maps of the surface albedo distribution have been drawn. From a comparison of the albedos inferred from satellite data with those actually observed in Ongul Strait, it is clear that the satellite-inferred, filtered narrow band albedos agree well with the daily means of ground-observed, unfiltered broad band albedo, despite systematic errors of about -4%. It is also clear that there is a characteristic pattern of surface albedo distribution in this area; the open sea has very low albedo of less than 5%, whereas most of the compact pack ice and fast ice has a high albedo of more than 60%. The albedo is lower in the eastern part of Lutzow-Holm Bay than in the western part; especially off the Soya Coast it is less than 40%. The ice sheet of Antarctica has a remarkably high albedo of more than 80%.

  1. Image in nuclear dosimetry using thermoluminescent dosimetry

    International Nuclear Information System (INIS)

    Guinsburg, G.; Matsuoka, M.; Watanabe, S.

    1987-01-01

    A low cost methodology to produce images of internal sick organs by radioisotopic intake, is presented. Dosimetries of thermoluminescent material and Teflon (ratio:50%) in bidimensional matrix shape are used with a Pb collimator. This collimator-bidimensional matrix system was tested ''in vivo'' and in thyroid phantoms using 99m Tc. A comparative evaluation between this method and the scintigraphy one is presented. (M.A.C.) [pt

  2. A pocket type thermoluminescent personnel dosimeter

    International Nuclear Information System (INIS)

    Vora, K.G.; Nagpal, J.S.; Pendurkar, H.K.; Gangadharan, P.

    1979-01-01

    A pocket type thermoluminescent personnel dosemeter using CaSO 4 : Dy phosphor is described. Two glass capillaries containing the phosphor are fitted into a plastic tube and covered by a cylindrical filter. The combination is fitted into an ink barrel of a fountain pen. The response of this Dy glass dosimeter was studied for various incident photon energies. A uniform response over the energy range from 33 keV to 1250 keV is achieved. (A.K.)

  3. Phosphor for thermoluminescent type radiation dosimeter

    International Nuclear Information System (INIS)

    Nada, N.; Yamashita, T.

    1975-01-01

    This has the accumulation effect of radiation energy and is mainly used as the element for thermoluminescent type radiation dosimeters. It has as the principal constituent a phosphor consisting of calcium sulfate as the principal constituent and other impurity elements such as dysprosium, thulium and the like. It is more sensitive by the order of 1 to 2 or more figures than the conventional ones and is excellent in the retention of absorbed radiation energy. (U.S.)

  4. Needle-type differential thermoluminescent dosemeter

    International Nuclear Information System (INIS)

    Kubu, M.

    1988-01-01

    The dosemeter serves to measure the depth distribution of absorbed dose in a phantom in mixed neutron and gamma radiation fields. It consists of a stratified cylindrical absorber in which alternate moderator and cadmium layers. Inside are two bores along the longitudinal axis for tubes filled with 6 LiF and 7 LiF powder thermoluminescent dosemeters. The device is easily portable and allows to carry out measurements with a high level of reproducibility. (J.B.). 4 figs

  5. Method of preparing a thermoluminescent phosphor

    Science.gov (United States)

    Lasky, Jerome B.; Moran, Paul R.

    1979-01-01

    A thermoluminescent phosphor comprising LiF doped with boron and magnesium is produced by diffusion of boron into a conventional LiF phosphor doped with magnesium. Where the boron dopant is made to penetrate only the outer layer of the phosphor, it can be used to detect shallowly penetrating radiation such as tritium beta ays in the presence of a background of more penetrating radiation.

  6. Performance tests on the NRPB thermoluminescent dosemeter

    CERN Document Server

    Shaw, K B

    1977-01-01

    Performance tests on the thermoluminescent dosemeter, designed at NRPB for use in the automated personal dosimetry system, are described. An ultra-thin lithium borate dosemeter has been developed for skin absorbed dose measurement. The X-ray, gamma-ray and beta-ray energy response of the dosemeter has been investigated and the angular response for the dosemeter has been examined. The annealing, read-out and stabilisation procedures for the dosemeter are described.

  7. Modeling Earth Albedo for Satellites in Earth Orbit

    DEFF Research Database (Denmark)

    Bhanderi, Dan; Bak, Thomas

    2005-01-01

    Many satellite are influences by the Earthøs albedo, though very few model schemes exist.in order to predict this phenomenon. Earth albedo is often treated as noise, or ignored completely. When applying solar cells in the attitude hardware, Earth albedo can cause the attitude estimate to deviate...... with as much as 20 deg. Digital Sun sensors with Earth albedo correction in hardware exist, but are expensive. In addition, albedo estimates are necessary in thermal calculations and power budgets. We present a modeling scheme base4d on Eartht reflectance, measured by NASA's Total Ozone Mapping Spectrometer......, in which the Earth Probe Satellite has recorded reflectivity data daily since mid 1996. The mean of these data can be used to calculate the Earth albedo given the positions of the satellite and the Sun. Our results show that the albedo varies highly with the solar angle to the satellite's field of view...

  8. Observations on the activation energy determination through the peak temperature at the maximum in thermoluminescence (Tl) experiments

    International Nuclear Information System (INIS)

    Furetta, C.; Azorin, J.; Rivera, T.

    2003-01-01

    The aim of this work is to give, for practical purposes in routine works, an easy way for obtaining approximated values of E which can be useful for testing, in a very quick way, the stability of the trap levels corresponding to the dosimetric peak in thermoluminescent materials used for environmental, personnel and clinical dosimetry applications. Furthermore, the E values obtained with this method can be used as input data for deconvolution procedure. (Author)

  9. In vivo dosimetry with semiconductor and thermoluminescent detectors applied to head and neck cancer treatment

    International Nuclear Information System (INIS)

    Viegas, Claudio Castelo Branco

    2003-03-01

    In vivo dosimetry in radiotherapy, i. e, the assessment of the doses received by patients during their treatments, permits a verification of the therapy quality. A routine of in vivo dosimetry is, undoubtedly, a direct benefit for the patient. Unfortunately, in Brazil and in Latin America this procedure is still a privilege for only a few patients. This routine is of common application only in developed countries. The aim of this work is to show the viability and implementation of a routine in vivo dosimetry, using diodes semiconductors and thermoluminescent dosimeters (TLD), at the radiotherapy section of the National Institute of Cancer in Brazil, in the case of head and neck cancer treatment. In order to reach that aim, the characteristics of the response of diodes ISORAD-p and LiF:Mg;Ti (TLD-100) thermoluminescent detectors in powder form were determined. The performance of those detectors for in vivo dosimetry was tested using an RANDO Alderson anthropomorfic phantom and, once their adequacy proved for the kind of measurements proposed, they were used for dose assessment in the case of tumour treatments in the head and neck regions, for Cobalt-60 irradiations. (author)

  10. Generalized Calibration of the Polarimetric Albedo Scale of Asteroids

    Science.gov (United States)

    Lupishko, D. F.

    2018-03-01

    Six different calibrations of the polarimetric albedo scale of asteroids have been published so far. Each of them contains its particular random and systematic errors and yields its values of geometric albedo. On the one hand, this complicates their analysis and comparison; on the other hand, it becomes more and more difficult to decide which of the proposed calibrations should be used. Moreover, in recent years, new databases on the albedo of asteroids obtained from the radiometric surveys of the sky with the orbital space facilities (the InfraRed Astronomical Satellite (IRAS), the Japanese astronomical satellite AKARI (which means "light"), the Wide-field Infrared Survey Explorer (WISE), and the Near-Earth Object Wide-field Survey Explorer (NEOWISE)) have appeared; and the database on the diameters and albedos of asteroids obtained from their occultations of stars has substantially increased. Here, we critically review the currently available calibrations and propose a new generalized calibration derived from the interrelations between the slope h and the albedo and between P min and the albedo. This calibration is based on all of the available series of the asteroid albedos and the most complete data on the polarization parameters of asteroids. The generalized calibration yields the values of the polarimetric albedo of asteroids in the system unified with the radiometric albedos and the albedos obtained from occultations of stars by asteroids. This, in turn, removes the difficulties in their comparison, joint analysis, etc.

  11. Dose measurements in dental radiology using thermoluminescent dosimetry;Medicoes de dose em radiodiagnostico odontologico utilizando dosimetria termoluminescente

    Energy Technology Data Exchange (ETDEWEB)

    Chiara, Ana Claudia M. de; Costa, Alessandro M. [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras; Pardini, Luiz Carlos [Universidade de Sao Paulo (FORP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Odontologia

    2009-07-01

    The aim of this work was the implementation of a code of practice for dosimetry in dental radiology using the technique of thermoluminescent dosimetry. General principles for the use of thermoluminescent dosimeters were followed. The irradiations were performed using ten X-ray equipment for intra-oral radiography and an X-ray equipment for panoramic radiography. The incident air kerma was evaluated for five different exposure times used in clinical practice for intra-oral radiographs. Using a backscatter factor of 1.2, it was observed that approximately 40% of the entrance skin dose values found for intra-oral radiographs are above the diagnostic reference level recommended in national regulation. Different configurations of voltage and current were used representing the exposure as a child, woman and man for panoramic radiographs. The results obtained for the air kerma area product were respectively 53.3 +- 5.2 mGy.cm{sup 2}, 101.5 +- 9.5 mGy.cm{sup 2} and 116.8 +- 10.4 mGy.cm{sup 2}. The use of thermoluminescent dosimetry requires several procedures before a result is recorded. The use of dosimeters with ionization chambers or semiconductors provides a simple and robust method for routine measurements. However, the use of thermoluminescent dosimetry can be of great value to large-scale surveys to establish diagnostic reference levels. (author)

  12. Application of thermoluminescence measurements to detect irradiated strawberries

    International Nuclear Information System (INIS)

    Heide, L.; Guggenberger, R.; Bogl, K.W.

    1990-01-01

    The thermoluminescence intensity of unirradiated and irradiated strawberries was studied with regard to dose response, storage time, and different varieties. An identification method could finally be developed. Further investigations were carried out to determine the origin of the thermoluminescence effect, which was found to be attributable to mineral grains adhering to the sample surface

  13. Entrance surface dose measurements in mammography using thermoluminescence technique

    International Nuclear Information System (INIS)

    Rivera, T.; Vega C, H.R.; Manzanares A, E; Azorin, J.; Gonzalez, P.R.

    2007-01-01

    Full text: Of the various techniques that can be used for personnel dosimetry, thermoluminescence dosimetry (TLD) has emerged as a superior technique due to its manifold advantages over other methods of dose estimation. Various phosphors have been therefore investigated regarding their suitability for dosimetry. In this paper, a dosimetry system based on thermally stimulated luminescence (TSL) from zirconium oxide phosphors embedded in polytetrafluorethylene (ZrO 2 +PTFE) was developed for entrance surface doses (ES) measurements in mammography. Small ZrO 2 pellets of 5 mm in diameter and 0.8 mm in thickness were used. The reproducibility of measurements and linearity of ZrO 2 were also studied. The results were compared with those obtained from LiF:Mg,Cu,P usually used for the determination of absorbed dose in mammography. Measurements both per unit air kerma and In vivo were performed using a mammography unit model DMR (General Electric). The results showed that ZrO 2 TLDs can be used for the same X-ray dosimetry applications as LiF:Mg,Cu,P, with each type having the disadvantage of a response dependent on energy, particularly at low energies. These results indicate a considerable potential for use in routine control and In vivo ES measurements in mammography. (Author)

  14. Comparative study of thermoluminescent, radiophotoluminescent and photographic dosemeters

    International Nuclear Information System (INIS)

    Deus, S.F.

    1976-01-01

    Comparison was made between the response of three differents dosimetric systems, namely, photographic, thermoluminescent (TL) and radiophotoluminescent (RPL). The comparison was divided in two parts. The first was carried out in known radiation conditions (exposure, normal incidence, energy) and under controlled environment (approximately 27 0 C temperature, approximately 70% relative humidity). Under these conditions, the response as a function of exposure and energy, the relation of the linearity to the energy, the lowest detectable exposure, and the reproducibility, were studied. The response against esposure at 37 KeVef and at 1 MeV was found to be linear in the region of interest to routine personnel dosimetry for all dosimeters except for the filmes. In the second part, the relative response of the dosimeters was verified under the uncontrolled conditions of personnel dosimetry. As the CaSO 4 :Dy is the most sensitive dosimeter, comparison was made using this dosimeter as the standard, in which case one finds that 20 of 29 TLD-100 dosimeters give the same reading within 30%, 13 of 29 RPL dosimeters agree within 30%, and only 3 of 29 films fall within 30% [pt

  15. Albedo and transmittance of inhomogeneous stratus clouds

    Energy Technology Data Exchange (ETDEWEB)

    Zuev, V.E.; Kasyanov, E.I.; Titov, G.A. [Institute of Atmospheric Optics, Tomsk (Russian Federation)] [and others

    1996-04-01

    A highly important topic is the study of the relationship between the statistical parameters of optical and radiative charactertistics of inhomogeneous stratus clouds. This is important because the radiation codes of general circulation models need improvement, and it is important for geophysical information. A cascade model has been developed at the Goddard Space Flight Center to treat stratocumulus clouds with the simplest geometry and horizontal fluctuations of the liquid water path (optical thickness). The model evaluates the strength with which the stochastic geometry of clouds influences the statistical characteristics of albedo and the trnasmittance of solar radiation.

  16. Impact of Atmospheric Albedo on Amazon Evapotranspiration

    Science.gov (United States)

    Lopes, A. V.; Thompson, S. E.; Dracup, J. A.

    2013-12-01

    The vulnerability of the Amazon region to climate and anthropogenic driven disturbances has been the subject of extensive research efforts, given its importance in the global and regional climate and ecologic systems. The evaluation of such vulnerabilities requires the proper understanding of physical mechanisms controlling water and energy balances and how the disturbances change them. Among those mechanisms, the effects of atmospheric albedo on evapotranspiration have not been fully explored yet and are explored in this study. Evapotranspiration in the Amazon is sustained at high levels across all seasons and represents a large fraction of water and energy surface budgets. In this study, statistical analysis of data from four flux towers installed at Amazon primary forest sites was employed to quantify the impact of atmospheric albedo, mostly resulted from cloudiness, on evapotranspiration and to compare it to the effect of water limitation. Firstly, the difference in eddy-flux derived evapotranspiration at the flux towers under rainy and non-rainy antecedent conditions was tested for significance. Secondly, the same statistical comparison was performed under cloudy and clear sky conditions at hourly and daily time scales, using the reduction in incoming solar radiation as an indicator of cloudiness. Finally, the sensitivity of seasonal evapotranspiration totals to atmospheric albedo resulted from rainfall patterns is evaluated. That was done by sampling daily evapotranspiration estimates from empirical probability distribution functions conditioned to rainfall occurrence and then varying the number of dry days in each season. It was found that light limitation is much more important than water limitation in the Amazon, resulting in up to 43% reduction in daily evapotranspiration. Also, this effect varies by location and by season, the largest impact being in wet season, from December do January. Moreover, seasonal evapotranspiration totals were found to be

  17. Thermoluminescence sensitivity of ulexite after UV irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Topaksu, M., E-mail: mats@cu.edu.tr [Cukurova University, Arts-Sciences Faculty, Physics Department, 01330 Adana (Turkey); CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Correcher, V. [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Garcia-Guinea, J. [Museo Nacional de Ciencias Naturales, (CSIC), C/José Gutiérrez Abascal 2, 28006 Madrid (Spain)

    2015-04-15

    Highlights: •UV-induced thermoluminescence emission of Turkish ulexite was studied. •There are three groups of components. •The UV exposures were performed at controlled temperatures. -- Abstract: The effects of UV radiation on the thermoluminescence (TL) properties of natural materials, in contrast to synthetic materials, have been scarcely studied. We report on the UV-induced thermoluminescence emission of a Turkish ulexite (NaCaB{sub 5}O{sub 6}(OH){sub 6}·5H{sub 2}O) that displays very complex TL glow curves, with at least three groups of components peaked at 130–140 °C, 240 °C and, 340 °C, wherein the last group is weaker. Such emission could be associated with structural changes in the lattice as well as alkali self-diffusion processes. The UV exposure performed at controlled temperatures (at room temperature (RT), 50 °C and 100 °C) produced a (i) different evolutions of the intensities of each maximum, which are directly related to the controlled thermal treatment; (ii) different intensity ratios among the groups of components; (iii) different activation energies (E{sub a}) (1.13 eV for RT, 0.99 eV for 50 °C and 0.49 eV for 100 °C) calculated using the initial rise method; and (iv) similar scattering values (12.4%, 8.2% and 12.8%), which were not a function of the controlled temperature. The thermal stability tests conducted on this borate at different temperatures, based on the T{sub stop} protocol, confirm the presence of a continuum in the distribution of the trap system with progressively increasing E{sub a} (from 0.60 to 0.90 eV)

  18. Reactor Gamma Heat Measurements with Calorimeters and Thermoluminescence Dosimeters

    DEFF Research Database (Denmark)

    Haack, Karsten; Majborn, Benny

    1973-01-01

    Intercomparison measurements of reactor γ-ray heating were carried out with calorimeters and thermoluminescence dosimeters. Within the measurement uncertainties the two methods yield coincident results. In the actual measurement range thermoluminescence dosimeters are less accurate than calorimet......Intercomparison measurements of reactor γ-ray heating were carried out with calorimeters and thermoluminescence dosimeters. Within the measurement uncertainties the two methods yield coincident results. In the actual measurement range thermoluminescence dosimeters are less accurate than...... calorimeters, but possess advantages such as a small probe size and the possibility of making simultaneous measurements at many different positions. Hence, thermoluminescence dosimeters may constitute a valuable supplement to calorimeters for reactor γ-ray heating measurements....

  19. Thermoluminescent response of LaAlO3:Pr

    International Nuclear Information System (INIS)

    Morales H, A.; Zarate M, J.; Azorin N, J.; Rivera M, T.

    2015-10-01

    In this study, the thermoluminescence response of doped lanthanum aluminate (LaAlO 3 ) with praseodymium ion (Pr) obtained by the Pechini method and drying by the spraying technique Spry Dryer was studied. The obtained powders were analyzed structurally by the X-ray diffraction technique; the morphological characterization was by the scanning electron microscopy technique. The obtained powders at 800 degrees C presented crystallinity and showed a Rhombohedral crystal structure, this phase was observed by X-ray diffraction patterns. Thermoluminescence response of LaAlO 3 :Pr showed a brightness curve with a peak centered at 157 degrees C. The sensitivity of the doped samples was improved about 90 times in comparison with the undoped sample. Thermoluminescence response in function of the wavelength showed a maximum at 230 nm, reproducibility of thermoluminescence response was ±50%. Also the fading in thermoluminescence response was studied. (Author)

  20. Albedo of the ice-covered Weddell and Bellingshausen Sea

    OpenAIRE

    A. I. Weiss; J. C. King; T. A. Lachlan-Cope; R. S. Ladkin

    2011-01-01

    This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo which were conducted in the sea ice areas of the Weddell and Bellingshausen Sea show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albed...

  1. Summer Arctic sea ice albedo in CMIP5 models

    OpenAIRE

    Koenigk, T.; Devasthale, A.; Karlsson, K.-G.

    2014-01-01

    Spatial and temporal variations of summer sea ice albedo over the Arctic are analyzed using an ensemble of historical CMIP5 model simulations. The results are compared to the CLARA-SAL product that is based on long-term satellite observations. The summer sea ice albedo varies substantially among CMIP5 models, and many models show large biases compared to the CLARA-SAL product. Single summer months show an extreme spread of ice albedo among models; July values vary between 0....

  2. An experimental system for thermoluminescent dosimetry

    International Nuclear Information System (INIS)

    Perry, K.E.G.; George, E.

    1965-08-01

    A thermoluminescent dosimeter (T.L.D.) reader has been developed for experimental investigations on the use of lithium fluoride for 'finger tip' dosimetry. The design of the reader is based on the maximum use of standard electronic units in the A.E.R.E. Type 2000 series but some new unit development has been necessary. The reader gives improved experimental facilities over present commercially-available designs. The technique for 'finger-tip' dosimetry is described and the initial experimental results are given. (author)

  3. Thermoluminescence detected in Magicicada sp. exoskeletons

    International Nuclear Information System (INIS)

    Fields, D.E.; Randall, R.B.; Bauman, C.E. III

    1979-01-01

    Thermoluminescent emission from the irradiated exoskeletons of cicada have been observed. At a heating rate of approximately 60 0 C/min. the peak light emission temperature was 183 +- 3 0 C. This effect corresponds to charge-carrier trap parameters of Esub(a) = 0.82 +- 0.04 eV and w 0 = 10sup(9.1 +- 0.5) sec -1 . Response to filtered γ radiation of 50-kV peak energy was on the order of 3.2 x 10 6 photons/R/g. Insect exoskeletons are thus potentially useful as dosimeters. (author)

  4. Thermoluminescence dating of some Hungarian medieval churches

    International Nuclear Information System (INIS)

    Kasa, I.; Bajnoczy, G.

    1984-01-01

    Thermoluminescence dating of three Hungarian historic churches was performed using the quarz inclusion technique and sup(60)Co gamma irradiation. Quarz grains obtained from the bricks were irradiated and the radiation doses were measured by CaSOsub(4):Dy TL dosemeters. Glow curves of irradiated and non-irradiated samples were also measured. From the results it was concluded that the ages of two churches were 10 and 30 percent less, respectively, than the ages estimated earlier. The age of the third church proved to be correct. (R.P.)

  5. Accuracy and precision in thermoluminescence dosimetry

    International Nuclear Information System (INIS)

    Marshall, T.O.

    1984-01-01

    The question of accuracy and precision in thermoluminescent dosimetry, particularly in relation to lithium fluoride phosphor, is discussed. The more important sources of error, including those due to the detectors, the reader, annealing and dosemeter design, are identified and methods of reducing their effects on accuracy and precision to a minimum are given. Finally, the accuracy and precision achievable for three quite different applications are discussed, namely, for personal dosimetry, environmental monitoring and for the measurement of photon dose distributions in phantoms. (U.K.)

  6. Thermoluminescent dosimetry for LDEF experiment M0006

    International Nuclear Information System (INIS)

    Chang, J.Y.; Giangano, D.; Kantorcik, T.; Stauber, M.; Snead, L.

    1992-01-01

    Experiment M0006 on the Long Duration Exposure Facility had as its objective the investigation of space radiation effects on various electronic and optical components, as well as on seed germination. The Grumman Corporate Research Center provided the radiation dosimetric measurements for M0006, comprising the preparation of thermoluminescent dosimeters (TLD) and the subsequent measurement and analysis of flight exposed and control samples. In addition, various laboratory exposures of TLD's with gamma rays and protons were performed to obtain a better understanding of the flight exposures

  7. Albedo of the ice covered Weddell and Bellingshausen Seas

    OpenAIRE

    A. I. Weiss; J. C. King; T. A. Lachlan-Cope; R. S. Ladkin

    2012-01-01

    This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo, which were conducted in the sea ice areas of the Weddell and Bellingshausen Seas show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo o...

  8. Short-wave albedo of a pine forest

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, A.

    1985-06-01

    In this paper nine years of continuous records of the short-wave albedo above a Scotch pine forest in middle Europe were analysed. Special emphasis was given to the dependencies of the albedo on its diurnal variation, its annual variation, the solar altitude, the structure of the stand, the cloud cover, the soil moisture and the spectral reflectance. A long-termed trend of the albedo could not be found, e.g. caused by the stand growth. Finally the annual variation of the albedo of the Scotch pine forest was compared with measurements above different surface types in middle Europe.

  9. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    OpenAIRE

    Y. Liu; W. Wu; M. P. Jensen; T. Toto

    2011-01-01

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surfaced-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fractio...

  10. Thermoluminescence dosimetry materials: properties and uses

    International Nuclear Information System (INIS)

    McKeever, S.W.S.; Moscovitch, M.; Townsend, P.D.

    1995-01-01

    This book selects a range of the most popular thermoluminescence dosemeter (TLD) materials in use today and provides a critical account of their thermoluminescence (TL) and dosimetric properties. The information provided includes in-depth discussions of TL mechanisms, including an account of luminescence properties, and relevant information regarding dosimetric characteristics. The book is intended for those involved in TLD materials research, and for technicians and workers involved in the practical application of these materials in TL dosimetry. The advent of modern spectroscopic methods for measuring TL emission spectra (the so-called ''3-D'' presentation) seemed to the authors to be an invitation to compile such spectra for all the major TLD materials. Further consideration led to an expansion of the initial idea to include a compilation of dosimetric properties. One intention is to provide a synopsis of the TL and dosimetric properties of the most widely used TLD materials currently available and to form a link between the solid state defect properties of these materials and their actual dosimetric properties. A second intention is to provide a solid framework from which future studies of TLD materials could be launched. Too often in the past research into TLD materials has been haphazard, to say the least. By illustrating the links between solid state physics and the radiation dosimetry properties of these materials the book points to the future and to the pressing need for enhanced research on TLD materials. (Author)

  11. Thermoluminescence method for detection of irradiated food

    International Nuclear Information System (INIS)

    Pinnioja, S.

    1998-01-01

    A method of thermoluminescence (TL) analysis was developed for the detection of irradiated foods. The TL method is based on the determination of thermoluminescence of adhering or contaminating minerals separated from foods by wet sieving and treatment with high density liquid. Carbon tetrachloride provided a suitable alternative for foods that form gels with water. Thermoluminescence response of minerals in a first TL measurement is normalised with a second TL measurement of the same mineral sample after calibration irradiation to a dose of 5 kGy. The decision about irradiation is made on the basis of a comparison of the two TL spectra: if the two TL glow curves match in shape and intensity the sample has been irradiated, and if they are clearly different it has not been irradiated. An attractive feature of TL analysis is that the mineral material itself is used for calibration; no reference material is required. Foods of interest in the investigation were herbs, spices, berries and seafood. The presence of minerals in samples is a criterion for application of the method, and appropriate minerals were found in all herbs, spices and berries. The most common minerals in terrestrial food were tecto-silicates - quartz and feldspars - which with their intense and stable thermoluminescence were well suited for the analysis. Mica proved to be useless for detection purposes, whereas carbonate in the form of calcite separated from intestines of seafood was acceptable. Fading of the TL signal is considerable in the low temperature part of the glow curve during a storage of several months after irradiation. However, spices and herbs could easily be identified as irradiated even after two years storage. Conditions for seafood, which is stored in a freezer, are different, and only slight fading was observed after one year. The effect of mineral composition and structure on TL was studied for feldspars. Feldspars originating from subtropical and tropical regions exhibit lower TL

  12. Thermoluminescence method for detection of irradiated food

    Energy Technology Data Exchange (ETDEWEB)

    Pinnioja, S

    1998-12-31

    A method of thermoluminescence (TL) analysis was developed for the detection of irradiated foods. The TL method is based on the determination of thermoluminescence of adhering or contaminating minerals separated from foods by wet sieving and treatment with high density liquid. Carbon tetrachloride provided a suitable alternative for foods that form gels with water. Thermoluminescence response of minerals in a first TL measurement is normalised with a second TL measurement of the same mineral sample after calibration irradiation to a dose of 5 kGy. The decision about irradiation is made on the basis of a comparison of the two TL spectra: if the two TL glow curves match in shape and intensity the sample has been irradiated, and if they are clearly different it has not been irradiated. An attractive feature of TL analysis is that the mineral material itself is used for calibration; no reference material is required. Foods of interest in the investigation were herbs, spices, berries and seafood. The presence of minerals in samples is a criterion for application of the method, and appropriate minerals were found in all herbs, spices and berries. The most common minerals in terrestrial food were tecto-silicates - quartz and feldspars - which with their intense and stable thermoluminescence were well suited for the analysis. Mica proved to be useless for detection purposes, whereas carbonate in the form of calcite separated from intestines of seafood was acceptable. Fading of the TL signal is considerable in the low temperature part of the glow curve during a storage of several months after irradiation. However, spices and herbs could easily be identified as irradiated even after two years storage. Conditions for seafood, which is stored in a freezer, are different, and only slight fading was observed after one year. The effect of mineral composition and structure on TL was studied for feldspars. Feldspars originating from subtropical and tropical regions exhibit lower TL

  13. Microcomputer-controlled thermoluminescent analyser IJS MR-200; Mikroracunalniski termoluminescentni analizator IJS MR-200

    Energy Technology Data Exchange (ETDEWEB)

    Mihelic, M; Miklavzic, U; Rupnik, Z; Satalic, P; Spreizer, F; Zerovnik, I [Institut Jozef Stefan, Ljubljana (Yugoslavia)

    1985-07-01

    Performances and concept of the multipurpose, microcomputer-controlled thermoluminescent analyser, designed for use in laboratory work TL dosemeters as well as for routine dose readings in the range from ecological to accident doses is described. The main features of the analyser are: time-linear sampling, digitalisation, storing, and subsequent displaying on the monitor time scale of the glow and and temperature curve of the TL material; digital stabilization, control and diagnostic of the analog unit; ability of storing 7 different 8-parametric heating programs; ability of storing 15 evaluation programs defined by 2 or 4 parameters and 3 different algorithms (altogether 5 types of evaluations). Analyser has several features intended for routine work: 9 function keys and possibilities of file forming on cassette or display disc, of dose calculation and averaging, of printing reports with names, and possibility of additional programming in Basic. (author)

  14. Cloud albedo increase from carbonaceous aerosol

    Directory of Open Access Journals (Sweden)

    W. R. Leaitch

    2010-08-01

    Full Text Available Airborne measurements from two consecutive days, analysed with the aid of an aerosol-adiabatic cloud parcel model, are used to study the effect of carbonaceous aerosol particles on the reflectivity of sunlight by water clouds. The measurements, including aerosol chemistry, aerosol microphysics, cloud microphysics, cloud gust velocities and cloud light extinction, were made below, in and above stratocumulus over the northwest Atlantic Ocean. On the first day, the history of the below-cloud fine particle aerosol was marine and the fine particle sulphate and organic carbon mass concentrations measured at cloud base were 2.4 μg m−3 and 0.9 μg m−3 respectively. On the second day, the below-cloud aerosol was continentally influenced and the fine particle sulphate and organic carbon mass concentrations were 2.3 μg m−3 and 2.6 μg m−3 respectively. Over the range 0.06–0.8 μm diameter, the shapes of the below-cloud size distributions were similar on both days and the number concentrations were approximately a factor of two higher on the second day. The cloud droplet number concentrations (CDNC on the second day were approximately three times higher than the CDNC measured on the first day. Using the parcel model to separate the influence of the differences in gust velocities, we estimate from the vertically integrated cloud light scattering measurements a 6% increase in the cloud albedo principally due to the increase in the carbonaceous components on the second day. Assuming no additional absorption by this aerosol, a 6% albedo increase translates to a local daytime radiative cooling of ∼12 W m−2. This result provides observational evidence that the role of anthropogenic carbonaceous components in the cloud albedo effect can be much larger than that of anthropogenic sulphate, as some global simulations have indicated.

  15. Anthropogenic desertification by high-albedo pollution Observations and modeling

    Science.gov (United States)

    Otterman, J.; Rosenberg, N. W.; Rosenberg, E.

    1974-01-01

    ERTS-1 MSS albedo data of Western Negev, Sinai and the Gaza strip are presented. A sharp contrast in albedo exists across the Negev-Sinai and Negev-Gaza strip borders. Anthropogenic desertification has occurred on the Arab side due to overgrazing and Bedouin agriculture, whereas natural vegetation grows much more abundantly on the Israeli side.

  16. Inversion of the Earth spherical albedo from radiation-pressure

    Science.gov (United States)

    Wilkman, Olli; Herranen, Joonas; Näränen, Jyri; Virtanen, Jenni; Koivula, Hannu; Poutanen, Markku; Penttilä, Antti; Gritsevich, Maria; Muinonen, Karri

    2017-04-01

    We are studying the retrieval of the spherical albedo and net radiation of the Earth from the perturbations caused by the planet's radiation on the dynamics of its satellites. The spherical or Bond albedo gives the ratio of the fluxes incident on and scattered by the planet. The net radiation represents the net heat input into the planet's climate system and drives changes in its atmospheric, surface, and ocean temperatures. The ultimate aim of the study is inverting the problem and estimating the Earth albedo based on observations of satellites, simultaneously improving the space-geodetic positioning accuracy. Here we investigate the effect of the spherical albedo on satellite orbits with the help of a simplified model. We simulate the propagation of satellite orbits using a new simulation software. The simulation contains the main perturbing forces on medium and high Earth orbits, used by, e.g., navigation satellites, including the radiation pressure of reflected sunlight from the Earth. An arbitrary satellite shape model can be used, and the rotation of the satellite is modeled. In this first study, we use a box-wing satellite model with a simple surface BRDF. We also assume a diffusely reflecting Earth with a single global albedo value. We vary the Earth albedo and search for systematic effects on different orbits. Thereafter, we estimate the dependence of the albedo accuracy on the satellite positioning and timing data available. We show that the inversion of the spherical albedo with reasonable accuracy is feasible from the current space-geodetic measurements.

  17. Albedo decline on Greenland's Mittivakkat Gletscher in a warming climate

    DEFF Research Database (Denmark)

    Mernild, Sebastian H; Malmros, Jeppe K.; Yde, Jacob Clement

    2015-01-01

    Albedo is one of the parameters that govern energy availability for snow and ice surface ablation, and subsequently the surface mass balance conditions of temperate glaciers and ice caps (GIC). Here, we document snow and ice albedo changes for Mittivakkat Gletscher (MG) in Southeast Greenland (20...

  18. LLL development of a combined etch track: albedo dosimeter

    International Nuclear Information System (INIS)

    Griffith, R.V.; Fisher, J.C.; Harder, C.A.

    1977-01-01

    The addition of polycarbonate sheet to albedo detectors for electrochemical etching provides a simple, inexpensive way to reduce the spectral sensitivity of the personnel dosimeter without losing the albedo features of sensitivity and ease of automation. The ECEP technique also provides the dosimetrist with the potential for identifying conditions of body orientation that might otherwise lead to significant error in dosimeter evaluation

  19. Spectral and diurnal variations in clear sky planetary albedo

    Science.gov (United States)

    Briegleb, B.; Ramanathan, V.

    1982-01-01

    Spectral and diurnal variations in the clear sky planetary albedo of the earth are calculated using a radiative transfer model to obtain January and July values for a 5 deg x 5 deg global grid. The model employs observed climatological values of temperatures, humidities, snow and sea-ice cover. The diurnal cycle of clear sky albedo is calculated in the following intervals: 0.2-0.5, 0.5-0.7, and 0.7-4 microns. Observed ozone distribution is specified as a function of latitude and season. The 0.2-0.5 micron spectral albedo is 10-20% higher than the total albedo for all latitudes because of Rayleigh scattering; the 0.5-0.7 micron albedo differs from the total albedo by 1-2% for most latitudes, while the 0.7-4 micron albedo is 5-10% lower than the total because of strong atmospheric absorption. Planetary albedo decreases from morning to local noon, with diurnal variations being particularly strong over water.

  20. Authenticity test in ceramics and archaeological figures by thermoluminescence

    International Nuclear Information System (INIS)

    Ramirez L, A.; Schaaf, P.; Filloy, L.

    1999-01-01

    At present exists quite a lot of false archaeological pieces which provokes doubts about the legitimacy of the pieces. In this work it is presented the Authenticity test by Thermoluminescence realized at the urn of the goddess 13 serpent of the zapotec culture of Oaxaca which is exposed in Mexico City. The original piece contains crystalline structures which present hardly the thermoluminescence phenomena by the presence of 238 U, 232 Th, and 40 K getting with this the form and intensity of the natural thermoluminescence curve of an archaeological piece which shows a Tl peak and allows to know so if it was made recently or not. (Author)

  1. NEOWISE REACTIVATION MISSION YEAR TWO: ASTEROID DIAMETERS AND ALBEDOS

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, C. R.; Cutri, R. M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Mainzer, A.; Bauer, J.; Kramer, E. A.; Masiero, J.; Sonnett, S. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T. [Planetary Science Institute, Tucson, AZ (United States); Wright, E. L., E-mail: cnugent@ipac.caltech.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±∼20% and ±∼40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  2. Use of wrist albedo neutron dosimeters

    International Nuclear Information System (INIS)

    Hankins, D.E.

    1983-01-01

    We are developing a wrist dosimeter that can be used to measure the exposure at the wrist to x-rays, gamma rays, beta-particles, thermal neutrons and fast neutrons. It consists of a modified Hankins Type albedo neutron dosimeter and also contains three pieces of CR-39 plastic. ABS plastic in the form of an elongated hemisphere provides the beta and low energy x-ray shielding necessary to meet the requirement of depth dose measurements at 1 cm. The dosimeter has a beta window located in the side of the hemisphere oriented towards an object being held in the hands. A TLD 600 is positioned under the 1 cm thick ABS plastic and is used to measure the thermal neutron dose. At present we are using Velcro straps to hold the dosimeter on the inside of the wrist. 9 figures

  3. Detection of irradiated food - methods and routine applications

    International Nuclear Information System (INIS)

    Schreiber, G.A.; Helle, N.; Boegl, K.W.

    1993-01-01

    Irradiation of food for the purposes of extension of shelf life, control of microbial load, reduction of pathogenic microorganisms and disinfection is regarded by many consumers with suspicion. One reason is the lack of methods within food-controlling laboratories which can detect irradiation treatment and which are applied to control correct labelling. This review describes the potential of various methods to reveal irradiation treatment. Special emphasis is given to the three most successful methods, thermoluminescence, electron spin resonance spectroscopy and detection of volatiles. The possibilities and limitations of applying the methods in routine control are discussed. (author)

  4. Generating multi-scale albedo look-up maps using MODIS BRDF/Albedo products and landsat imagery

    Science.gov (United States)

    Surface albedo determines radiative forcing and is a key parameter for driving Earth’s climate. Better characterization of surface albedo for individual land cover types can reduce the uncertainty in estimating changes to Earth’s radiation balance due to land cover change. This paper presents a mult...

  5. Thermoluminescence of laterites: applicability in dating

    International Nuclear Information System (INIS)

    Sankaran, A.V.; Nambi, K.S.V.; Sunta, C.M.

    1985-01-01

    The northward drift of the Indian subcontinent during the past geological periods brought it under the spell of humid tropical climate in post-mesozoic times which initiated chemical weathering processes (lateritization) of the ancient crustal rocks leading to neomineralization. In the present study, thermoluminescence (TL) of these 'later-formed minerals' has been used to date laterites from a number of localities in India. While the TL emission of most of the laterite samples was poor, three from Kerala, Tamil Nadu and Karnataka states, each derived from mineralogically dissimilar parent rock, yielded measurable TL and provided dates in the range of 2 to 3.6 x 10 5 yr. It is suggested that TL dating can be a promising tool for such samples, and especially those with low alpha activity (U, Th at sub-ppm levels). (author)

  6. Thermoluminescence of laterites: applicability in dating

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran, A V; Nambi, K S.V.; Sunta, C M

    1985-01-01

    The northward drift of the Indian subcontinent during the past geological periods brought it under the spell of humid tropical climate in post-mesozoic times which initiated chemical weathering processes (lateritization) of the ancient crustal rocks leading to neomineralization. In the present study, thermoluminescence (TL) of these 'later-formed minerals' has been used to date laterites from a number of localities in India. While the TL emission of most of the laterite samples was poor, three from Kerala, Tamil Nadu and Karnataka states, each derived from mineralogically dissimilar parent rock, yielded measurable TL and provided dates in the range of 2 to 3.6 x 10/sup 5/ yr. It is suggested that TL dating can be a promising tool for such samples, and especially those with low alpha activity (U, Th at sub-ppm levels).

  7. Adjustment model of thermoluminescence experimental data

    International Nuclear Information System (INIS)

    Moreno y Moreno, A.; Moreno B, A.

    2002-01-01

    This model adjusts the experimental results for thermoluminescence according to the equation: I (T) = I (a i * exp (-1/b i * (T-C i )) where: a i , b i , c i are the i-Th peak adjusted to a gaussian curve. The adjustments of the curve can be operated manual or analytically using the macro function and the solver.xla complement installed previously in the computational system. In this work it is shown: 1. The information of experimental data from a LiF curve obtained from the Physics Institute of UNAM which the data adjustment model is operated in the macro type. 2. A LiF curve of four peaks obtained from Harshaw information simulated in Microsoft Excel, discussed in previous works, as a reference not in macro. (Author)

  8. Thermoluminescent dosimetry in veterinary diagnostic radiology

    International Nuclear Information System (INIS)

    Hernández-Ruiz, L.; Jimenez-Flores, Y.; Rivera-Montalvo, T.; Arias-Cisneros, L.; Méndez-Aguilar, R.E.; Uribe-Izquierdo, P.

    2012-01-01

    This paper presents the results of Environmental and Personnel Dosimetry made in a radiology area of a veterinary hospital. Dosimetry was realized using thermoluminescent (TL) materials. Environmental Dosimetry results show that areas closer to the X-ray equipment are safe. Personnel Dosimetry shows important measurements of daily workday in some persons near to the limit established by ICRP. TL results of radiation measurement suggest TLDs are good candidates as a dosimeter to radiation dosimetry in veterinary radiology. - Highlights: ► Personnel dosimetry in laboratory veterinary diagnostic was determined. ► Student workplaces are safe against radiation. ► Efficiency value of apron lead was determined. ► X-ray beams distribution into veterinarian laboratory was measured.

  9. Thermoluminescent dosimetric properties of Descalvado sand

    International Nuclear Information System (INIS)

    Teixeira, M.I.; Caldas, L.V.E.

    2006-01-01

    Sand samples proceeding from Descalvado, Sao Paulo, were studied with regard to their dosimetric properties using the thermoluminescence technique (TL) for high doses. These sand samples present steady physical and chemical characteristics to the end items, and they are used in the glass industry and for casting. The TL curves of the samples were obtained after an irradiation at the Gamma-Cell system ( 60 Co), of IPEN. The glow curves present two peaks at 80 C and 220 C approximately. Calibration curves were obtained for doses between 50 Gy and 5 kGy. The results indicate that the sand samples can be used for high-doses dosimetry in several areas of applications of ionizing radiation. (Author)

  10. Thermoluminescent dosimetry in fluoroscopy of pediatric patients

    International Nuclear Information System (INIS)

    Garcia V, E.; Azorin N, J.; Hidalgo T, S.; Dies S, P.

    2016-10-01

    The use of thermoluminescent dosimeters in the area of medical physics and especially in radiology is of paramount importance to guarantee the quality of a particular study, which for this reason the need to verify by means of measurements of peripheral dose in studies of esophagogastroduodenal series by fluoroscopy using TLD of LiF:Mg, Ti. For this the necessary measurements were carried out directly in patients of the Children s Hospital of Mexico Federico Gomez. Previously characterized the dosimeters were used the graphs of the linear equation to obtain the absorbed dose of each dosimeter and was found that the values of the absorbed dose in each patient changes for various reasons like the anatomy, thickness of the tissues, age and exposure time during the study and was verify that none of the studies performed on patients exceeded dose levels that could affect healthy organs. (Author)

  11. Environmental radiation studies relevant to thermoluminescence dating

    International Nuclear Information System (INIS)

    Murray, A.S.; Bowman, S.G.E.; Aitken, M.J.

    1980-01-01

    To determine the age of a potsherd by the thermoluminescence (TL) technique, one must have an accurate knowledge of the cosmic and environmental gamma dose rate in quartz. This is obtained by leaving a sensitive TL dosimeter buried as near as possible to the position from which the sherd was removed. The ratios of the response of a quartz-like dosimeter to those of CaF 2 and LiF have been measured. This experiment used a 1-m cube of concrete containing 3000 ppM of uranium and its daughters. Smaller, less active matrixes of 40 K and thorium and its daughters have also been constructed. A means of making direct dose-rate determinations when the site context remains but burial of a dosimeter is impractical was developed using a NaI(Tl) system. The equipment was field tested on approx. 40 Peruvian archaeological sites, and results are compared with CaF 2 measurements

  12. Thermoluminescent dosimetric properties of Descalvado sand

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, M.I.; Caldas, L.V.E

    2006-07-01

    Sand samples proceeding from Descalvado, Sao Paulo, were studied with regard to their dosimetric properties using the thermoluminescence technique (TL) for high doses. These sand samples present steady physical and chemical characteristics to the end items, and they are used in the glass industry and for casting. The TL curves of the samples were obtained after an irradiation at the Gamma-Cell system ({sup 60} Co), of IPEN. The glow curves present two peaks at 80 C and 220 C approximately. Calibration curves were obtained for doses between 50 Gy and 5 kGy. The results indicate that the sand samples can be used for high-doses dosimetry in several areas of applications of ionizing radiation. (Author)

  13. Ultraviolet dosimetry using thermoluminescent phosphors - an update

    International Nuclear Information System (INIS)

    Nagpal, J.S.

    1998-04-01

    Intrinsic response of various thermoluminescent (TL) materials such as CaSO 4 (Dy, Eu, Mn, Sm, Tb, or Tm), LiF (Mg, Cu, P), Mg 2 SiO 4 :Tb, CaF 2 :Dy, CaF 2 :Tb, ThO 2 :Tb and Al 2 O 3 (Si, Ti); cathodoluminescent phosphors Y 3 Al 5 O 12 :Ce, Y 3 Al 5 O 12 :Tb and Y(V,P)O 4 :Eu; and fluorescent lamp phosphors calcium halophosphate (Mn,Sb) and Ce Mg aluminate (Eu, Tb) to ultraviolet (UV) radiations has been studied. Intrinsic TL response of most of the phosphors is rate (radiant flux) dependent. For the first time, UV response of the materials is reported for a fixed total radiant energy (total UV dose), at a single radiant flux (260 μW.cm -2 ), for an appropriate comparison. A wide range of UV sensitivity is observed. Studies conducted using UV radiation from two unfiltered low pressure mercury lamps show significant differences in glow curves, as compared to those obtained with nearly monochromatic UV radiations. Photons of wavelength 365 nm induce bleaching of TL induced by 254 nm photons, in most of the materials. Sequential/tandem exposures to 254 nm and 365 nm photons have yielded new but alarming results in CaF 2 :Tb. Preferential induction and bleaching of specific TL glow peaks by 365 nm and 254 nm photons are interesting characteristics discovered in CaSO 4 :Eu. Photoluminescence studies of Tb 3+ and Eu 3+ activated phosphors have augmented the inferences drawn from the bleaching effects produced by 365 nm photons. Earlier work carried out on phototransferred thermoluminescence of CaSO 4 :Dy-teflon dosimeters, TLD-100, Mg 2 SiO 4 :Tb and Al 2 O 3 (Si,Ti) has also been reviewed. (author)

  14. Thermoluminescence in alkali halides irradiated at 80K

    International Nuclear Information System (INIS)

    Jimenez de Castro, M.

    1978-01-01

    The thermoluminescence, the thermally stimulated currents and the thermal stability of the F centres induced in pure NaCl and KC1 crystals by X irradiation at 80K have been studied in detail, in the range between 80 and 300K. The thermoluminescent processes induced by illumination at 80K with F light in samples previously irradiated at room temperature has also been studied. It has been clearly observed the existence of thermoluminescent processes due to electrons and holes thermally released from traps, in which the F centres are not involved. The existence of hole-F centre recombination has not been observed. There are several thermoluminescent processes in both materials which are scribed to the recombination of F centres with mobile interstitial halogen atoms thermally released from traps, which are likely monovalent impurities in this temperature interval. The light emitting stage in these processes is originated by the formation of self trapped excitons. (Author) 66 refs

  15. Historical note: thermoluminescent dosimetry (LiF) 1950-51

    International Nuclear Information System (INIS)

    Heckelsberg, L.F.

    1980-01-01

    The early history of thermoluminescent dosimetry has not been adequately described and one of the first workers in this field takes this opportunity to record more fully the history of the period. (author)

  16. Natural dose level determination at Johor State with thermoluminescence dosimetry

    International Nuclear Information System (INIS)

    Ahmad Termizi Ramli; Yusof Jasman

    1995-01-01

    This paperwork presented the results of using thermoluminescence dosimetry (TLD) method in measuring background dose level, which is done at State of Johor, South Malaysia. The problems faced also discussed

  17. Storage Telemetry of Radionuclide Tracers by Implantable Thermoluminescent Dosimeters

    DEFF Research Database (Denmark)

    Bojsen, J.; Møller, U.; Christensen, Poul

    1977-01-01

    A storage telemetrical method using thermoluminescent (TL) dosimeters for long-term measurements of incorporated radioactive substances in unrestrained rats has been developed. The system has been used in combination with radiotelemetrical registration of the circadian temperature rhythm. By sequ...

  18. A theoretical description of complex thermoluminescence curves: Pt. 1

    International Nuclear Information System (INIS)

    Kantorovich, L.N.; Fogel, G.M.; Gotlib, V.I.

    1988-01-01

    Thermoluminescence kinetics has been discussed within the framework of a band model assuming an extensive retrapping of charge carriers in comparison with their recombination. Assuming that a luminophor has one type of recombination centre and an arbitrary number of trapping centres we succeeded in analysing complex thermoluminescence curves with an arbitrary number of peaks. It has been shown for an elementary peak that its form almost coincides with the Randall-Wilkins curve, and its intensity is proportional to the square of the absorbed dose. The effect of both the processes of localised charge carriers accumulation (irradiation and isothermal decay) and their redistribution on trapping centres during the thermoluminescence process have been dealt with taking into account the form and intensity of the thermoluminescence peaks. (author)

  19. 128 slice computed tomography dose profile measurement using thermoluminescent dosimeter

    International Nuclear Information System (INIS)

    Salehhon, N; Hashim, S; Karim, M K A; Ang, W C; Musa, Y; Bahruddin, N A

    2017-01-01

    The increasing use of computed tomography (CT) in clinical practice marks the needs to understand the dose descriptor and dose profile. The purposes of the current study were to determine the CT dose index free-in-air (CTDI air ) in 128 slice CT scanner and to evaluate the single scan dose profile (SSDP). Thermoluminescent dosimeters (TLD-100) were used to measure the dose profile of the scanner. There were three sets of CT protocols where the tube potential (kV) setting was manipulated for each protocol while the rest of parameters were kept constant. These protocols were based from routine CT abdominal examinations for male adult abdomen. It was found that the increase of kV settings made the values of CTDI air increased as well. When the kV setting was changed from 80 kV to 120 kV and from 120 kV to 140 kV, the CTDI air values were increased as much as 147.9% and 53.9% respectively. The highest kV setting (140 kV) led to the highest CTDI air value (13.585 mGy). The p -value of less than 0.05 indicated that the results were statistically different. The SSDP showed that when the kV settings were varied, the peak sharpness and height of Gaussian function profiles were affected. The full width at half maximum (FWHM) of dose profiles for all protocols were coincided with the nominal beam width set for the measurements. The findings of the study revealed much information on the characterization and performance of 128 slice CT scanner. (paper)

  20. Simulations of tropical rainforest albedo: is canopy wetness important?

    Directory of Open Access Journals (Sweden)

    Silvia N.M. Yanagi

    Full Text Available Accurate information on surface albedo is essential for climate modelling, especially for regions such as Amazonia, where the response of the regional atmospheric circulation to the changes on surface albedo is strong. Previous studies have indicated that models are still unable to correctly reproduce details of the seasonal variation of surface albedo. Therefore, it was investigated the role of canopy wetness on the simulated albedo of a tropical rainforest by modifying the IBIS canopy radiation transfer code to incorporate the effects of canopy wetness on the vegetation reflectance. In this study, simulations were run using three versions of the land surface/ecosystem model IBIS: the standard version, the same version recalibrated to fit the data of albedo on tropical rainforests and a modified version that incorporates the effects of canopy wetness on surface albedo, for three sites in the Amazon forest at hourly and monthly scales. The results demonstrated that, at the hourly time scale, the incorporation of canopy wetness on the calculations of radiative transfer substantially improves the simulations results, whereas at the monthly scale these changes do not substantially modify the simulated albedo.

  1. Surface albedo measurements in Mexico City metropolitan area

    Energy Technology Data Exchange (ETDEWEB)

    Castro, T; Mar, B; Longoria, R; Ruiz Suarez, L. G [Centro de Ciencias de la Atmosfera, UNAM, Mexico, D.F. (Mexico); Morales, L [Instituto de Geografia, UNAM, Mexico, D.F. (Mexico)

    2001-04-01

    Optical and thermal properties of soils are important input data for the meteorological and photochemical modules of air quality models. As development of these models increase on spatial resolution good albedo data become more important. In this paper measurements of surface albedo of UV (295-385 nm) and visible (450-550 nm) radiation are reported for different urban and rural surfaces in the vicinity of Mexico City. It was found for the downtown zone and average albedo value of 0.05 which is in very good agreement with reported values for urban surfaces. Our albedo values measured in UV region for grey cement and green grass are of 0.10 and 0.009, respectively, and quite similar to those found at the literature of 0.11 and 0.008 for those type of surfaces. [Spanish] Las propiedades opticas y termicas de suelos son datos importantes para los modulos meteorologicos y fotoquimicos de los modelos de calidad del aire. Conforme aumenta la resolucion espacial del modelo se vuelve mas importante contar con buenos datos de albedo. En este articulo se presentan mediciones de albedo superficial de radiacion Ultravioleta (295-385 nm) y visible (450-550 nm) para diferentes superficies urbanas. Los valores medidos de albedo en la region UV para cemento gris y pasto verde son de 0.10 y 0.009, respectivamente, y son muy similares a los reportados en la literatura, 0.11 y 0.008 para este tipo de superficies.

  2. Thermoluminescent behavior of diamond thin films exposed to ultraviolet radiation

    International Nuclear Information System (INIS)

    Barboza F, M.; Gastelum, S.; Melendrez, R.; Chernov, V.; Bernal, R.; Cruz V, C.; Brown, F.

    2002-01-01

    In this work the thermoluminescent properties of diamond thin films are discussed which are grown up through the chemical vapor method exposed to ultraviolet radiation of 200-280 nm. The films with thickness 3, 6, 9, 12, 180 and 500 microns were grown up using a precursor gas formed of H 2 -CH 4 -CO excited through microwave energy or hot filament.The structure and morphology of the films were examined through scanning electron microscopy, indicating the formation of different diamond polycrystal structures which depend on the type of heating of the precursor gas used as well as the film dimensions. In general, the brilliance curve depends on the sample and the wavelength of the irradiation ultraviolet light, however it presents clearly thermoluminescence bands in 148, 160, 272, 304, 320 and 324 C degrees. The maximum of the thermoluminescence efficiency is obtained for the case of sample exposure with light of 214 nm. The sample of 500 microns is what exhibits greater thermoluminescent efficiency of those studied samples. The thermoluminescent behavior in function of radiation dose presents regions of linearity and supra linearity for higher and small doses respectively. The disappearance of the thermoluminescent signal depends on the characteristics of the film and it can reach until a 30 % of loss before to reach the stability. (Author)

  3. Albedo's determination by the method of neutron impulse

    International Nuclear Information System (INIS)

    Flores Calderon, J.E.

    1982-01-01

    Experiments with non-stationary neutron transport in large cavity moderators (l>>Σsub(tr) -1 ) (where l is the characteristic cavity length and Σsub(tr) -1 the macroscopic transport section of the moderator) led to the method reported in this study which, based on neutron impulses for determining albedo of thermal neutrons, gave a precision greater by an order of magnitude over previous methods. A sufficient time interval after introduction of the neutron flux into the moderator chamber decreased exponentially the decay constant L, which was itself related to albedo by a function called f. Numerical calculations of albedo were assisted. (author)

  4. Incompatibility of sensitisation and re-estimation of lithium fluoride thermoluminescent phosphor

    International Nuclear Information System (INIS)

    Bartlett, D.T.; Sandford, D.J.

    1978-01-01

    A technique of useful sensitisation of lithium fluoride thermoluminescent phosphor has been reported by Mayhugh and Fullerton, (USAEC Report COO-1105-209, 1974). This technique differs from that previously described (Cameron and Zimmerman, USAEC Report COO-1105-102, 1965) in that during the anneal at 300 degrees C which follows the high pre-dose, the phosphor is simultaneously exposed to 254 nm ultraviolet light. It is reported that this method removes interfering centres and hence reduces the lowest detectable dose. Sensitisation also has the advantages of improved tissue equivalence and increased range of linearity. However, a disadvantage of both techniques of sensitisation is that for sensitised phosphor, absorbed doses cannot be re-estimated by photo-transferred thermoluminescence. Results are compared for discs of lithium fluoride in PTFE, some of which were sensitised by each method, and some left unsensitised. It is concluded that for routine personal dosimetry the disadvantages of the loss of the facility to re-estimate absorbed dose outweighs the reported advantages of sensitisation. (author)

  5. Leaked filters for energetic and angular dependence corrections of thermoluminescent response

    International Nuclear Information System (INIS)

    Manzoli, Jose Eduardo; Shammas, Gabriel Issa Jabra; Campos, Vicente de Paulo de

    2007-01-01

    Many thermoluminescent materials has been developed and used for photon personal dosimetry but no one has all desired characteristics alone. These characteristics include robustness, high sensitivity, energy photon independence, large range of photon energy detection, good reproducibility and small fading. The phosphors advantages begin to be more required and its disadvantages have became more apparent, in a global market more and more competitive. Calcium Sulfate Dysprosium doped (CaSO 4 :Dy) and Calcium Fluoride Manganese doped (CaF 2 :Mn) phosphor Thermoluminescent Dosimeters (TLDs) have been used by many laboratories. They are used in environmental and area monitoring, once they present more sensibility than other phosphors, like LiF:Mg. Theirs main disadvantage is the strong energetic dependence response, which must be corrected for theirs application in routine, where the kind of photon radiation is unknown a priori. An interesting way to make this correction is to interject a leaked filter between the beam and the phosphor, where the beam could strike the phosphor at any angle. In order to reduce the energetic dependence on any incidence angle, this work presents experimental and simulation studies on some filter geometries. It was made TL readings and simulations on TL responses to photon irradiations with gamma rays of 60 Co and X-rays of 33; 48 and 118 keV, on many incidence angles from zero to ninety degrees. The results pointed out the best filter thicknesses and widths, in order to optimize the correction of energetic dependence for the studied geometries. (author)

  6. Main Achievements 2003-2004 - Interdisciplinary Research - Radiation detection methods for health, earth and environmental sciences - Thermoluminescence (TL) detectors

    International Nuclear Information System (INIS)

    2005-01-01

    The IFJ has over 35 years of experience in the development, production and application of new types of thermoluminescence (TL) detectors, particularly LiF:Mg,Ti and LiF:Mg,Cu,P. Over 600,000 LiF detectors produced at the IFJ PAN are routinely applied in dosimetry services and hospitals in 30 countries. The current research in the field of thermoluminescence concentrates in space dosimetry and novel 2-dimensional detectors for medical applications. The space project (named Matroshka), organized by the European Space Agency, is one of the most ambitious dosimetry experiments in space. In February 2004 an anatomical model of the human body (a humanoid phantom), equipped with over 3500 dedicated thermoluminescent detectors (TLD), developed and produced at IFJ and tested at the Chiba heavy ion accelerator in Japan, was installed outside the International Space Station (ISS) to determine the cosmic radiation doses absorbed in human organs, which would be experienced by astronauts in open space. The phantom will remain in space for one year, after which the detectors will be returned to the IFJ for analysis

  7. An algorithm to determine backscattering ratio and single scattering albedo

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Matondkar, S.G.P.; Mascarenhas, A.A.M.Q.; Nayak, S.R.; Naik, P.

    Algorithms to determine the inherent optical properties of water, backscattering probability and single scattering albedo at 490 and 676 nm from the apparent optical property, remote sensing reflectance are presented here. The measured scattering...

  8. PROVE Surface albedo of Jornada Experimental Range, New Mexico, 1997

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this study was to determine the spatial variations in field measurements of broadband albedo as related to the ground cover and under a range of...

  9. Albedo neutron dosimetry in Germany: regulations and performance

    International Nuclear Information System (INIS)

    Luszik-Bhadra, M.; Zimbal, A.; Busch, F.; Jordan, M.; Eichelberger, A.; Engelhardt, J.; Martini, E.; Figel, M.; Haninger, T.; Frasch, G.; Guenther, K.; Seifert, R.; Rimpler, A.

    2014-01-01

    Personal neutron dosimetry has been performed in Germany using albedo dosemeters for >20 y. This paper describes the main principles, the national standards, regulations and recommendations, the quality management and the overall performance, giving some examples. (authors)

  10. ALBEDO PATTERN RECOGNITION AND TIME-SERIES ANALYSES IN MALAYSIA

    Directory of Open Access Journals (Sweden)

    S. A. Salleh

    2012-07-01

    Full Text Available Pattern recognition and time-series analyses will enable one to evaluate and generate predictions of specific phenomena. The albedo pattern and time-series analyses are very much useful especially in relation to climate condition monitoring. This study is conducted to seek for Malaysia albedo pattern changes. The pattern recognition and changes will be useful for variety of environmental and climate monitoring researches such as carbon budgeting and aerosol mapping. The 10 years (2000–2009 MODIS satellite images were used for the analyses and interpretation. These images were being processed using ERDAS Imagine remote sensing software, ArcGIS 9.3, the 6S code for atmospherical calibration and several MODIS tools (MRT, HDF2GIS, Albedo tools. There are several methods for time-series analyses were explored, this paper demonstrates trends and seasonal time-series analyses using converted HDF format MODIS MCD43A3 albedo land product. The results revealed significance changes of albedo percentages over the past 10 years and the pattern with regards to Malaysia's nebulosity index (NI and aerosol optical depth (AOD. There is noticeable trend can be identified with regards to its maximum and minimum value of the albedo. The rise and fall of the line graph show a similar trend with regards to its daily observation. The different can be identified in term of the value or percentage of rises and falls of albedo. Thus, it can be concludes that the temporal behavior of land surface albedo in Malaysia have a uniform behaviours and effects with regards to the local monsoons. However, although the average albedo shows linear trend with nebulosity index, the pattern changes of albedo with respects to the nebulosity index indicates that there are external factors that implicates the albedo values, as the sky conditions and its diffusion plotted does not have uniform trend over the years, especially when the trend of 5 years interval is examined, 2000 shows high

  11. IAU nomenclature for albedo features on the planet Mercury

    Science.gov (United States)

    Dollfus, A.; Chapman, C. R.; Davies, M. E.; Gingerich, O.; Goldstein, R.; Guest, J.; Morrison, D.; Smith, B. A.

    1978-01-01

    The International Astronomical Union has endorsed a nomenclature for the albedo features on Mercury. Designations are based upon the mythological names related to the god Hermes; they are expressed in Latin form. The dark-hued albedo features are associated with the generic term Solitudo. The light-hued areas are designated by a single name without generic term. The 32 names adopted are allocated on the Mercury map.

  12. Evaluation of coarse scale land surface remote sensing albedo product over rugged terrain

    Science.gov (United States)

    Wen, J.; Xinwen, L.; You, D.; Dou, B.

    2017-12-01

    Satellite derived Land surface albedo is an essential climate variable which controls the earth energy budget and it can be used in applications such as climate change, hydrology, and numerical weather prediction. The accuracy and uncertainty of surface albedo products should be evaluated with a reliable reference truth data prior to applications. And more literatures investigated the validation methods about the albedo validation in a flat or homogenous surface. However, the albedo performance over rugged terrain is still unknow due to the validation method limited. A multi-validation strategy is implemented to give a comprehensive albedo validation, which will involve the high resolution albedo processing, high resolution albedo validation based on in situ albedo, and the method to upscale the high resolution albedo to a coarse scale albedo. Among them, the high resolution albedo generation and the upscale method is the core step for the coarse scale albedo validation. In this paper, the high resolution albedo is generated by Angular Bin algorithm. And a albedo upscale method over rugged terrain is developed to obtain the coarse scale albedo truth. The in situ albedo located 40 sites in mountain area are selected globally to validate the high resolution albedo, and then upscaled to the coarse scale albedo by the upscale method. This paper takes MODIS and GLASS albedo product as a example, and the prelimarily results show the RMSE of MODIS and GLASS albedo product over rugged terrain are 0.047 and 0.057, respectively under the RMSE with 0.036 of high resolution albedo.

  13. Quantifying the ice-albedo feedback through decoupling

    Science.gov (United States)

    Kravitz, B.; Rasch, P. J.

    2017-12-01

    The ice-albedo feedback involves numerous individual components, whereby warming induces sea ice melt, inducing reduced surface albedo, inducing increased surface shortwave absorption, causing further warming. Here we attempt to quantify the sea ice albedo feedback using an analogue of the "partial radiative perturbation" method, but where the governing mechanisms are directly decoupled in a climate model. As an example, we can isolate the insulating effects of sea ice on surface energy and moisture fluxes by allowing sea ice thickness to change but fixing Arctic surface albedo, or vice versa. Here we present results from such idealized simulations using the Community Earth System Model in which individual components are successively fixed, effectively decoupling the ice-albedo feedback loop. We isolate the different components of this feedback, including temperature change, sea ice extent/thickness, and air-sea exchange of heat and moisture. We explore the interactions between these different components, as well as the strengths of the total feedback in the decoupled feedback loop, to quantify contributions from individual pieces. We also quantify the non-additivity of the effects of the components as a means of investigating the dominant sources of nonlinearity in the ice-albedo feedback.

  14. Data format translation routines

    International Nuclear Information System (INIS)

    Burris, R.D.

    1981-02-01

    To enable the effective connection of several dissimilar computers into a network, modification of the data being passed from one computer to another may become necessary. This document describes a package of routines which permit the translation of data in PDP-8 formats to PDP-11 or DECsystem-10 formats or from PDP-11 format to DECsystem-10 format. Additional routines are described which permit the effective use of the translation routines in the environment of the Fusion Energy Division (FED) network and the Elmo Bumpy Torus (EBT) data base

  15. Routines and Organizational Change

    DEFF Research Database (Denmark)

    Yi, Sangyoon; Becker, Markus; Knudsen, Thorbjørn

    2014-01-01

    Routines have been perceived as a source of inertia in the process of organizational change. In this study, we suggest an overlooked, but prevalent, mechanism by which the inertial nature of routines helps, rather than hinders, organizational adaptation. Routine-level inertia plays a hidden role...... to cope with its task environment. In our nuanced perspective, inertia is not only a consequence of adaptation but also a source of adaptation. This logic is helpful to understand why reliable but apparently inertial organizations keep surviving and often exhibit outstanding performance. We conclude...

  16. Thermoluminescent characteristics of synthetic hydroxyapatite (SHAp)

    International Nuclear Information System (INIS)

    Alvarez, R.; Rivera, T.; Guzman, J.; Piña-Barba, M.C.; Azorin, J.

    2014-01-01

    This paper presents the experimental results of the thermoluminescent (TL) characteristics of synthetic hydroxyapatite (SHAp) obtained by the sol–gel method. For preparation of the SHAp powders, phosphorus pentoxide (P 2 O 5 ) and calcium nitrate tetrahydrated (Ca(NO 3 ) 2 –4H 2 O) were used. The powders obtained were submitted at different temperatures. The structural and morphological characterization were carried out using X-ray diffraction (XRD) and scanning electron microscopy techniques. TL glow curve exhibited two peaks centered at around 200 °C and 300 °C. TL response of SHAp as a function of gamma absorbed dose was linear over a wide dose range. Fading of the storage information in the samples irradiated was also studied. The experimental results show that the synthetic hydroxyapatite obtained by the sol–gel method may have used in gamma radiation dosimetry applications. - highlights: • Dosimetric characteristics of SHAp under gamma irradiation effect were analyzed • SHAp powders were obtained by Sol–Gel method • Fading anomalous of HAp was performed showing 15% during 90 days • SHAp showed good dosimetric characteristics. • Dosimetric characteristics of SHAp have not been reported yet in the literature before this paper

  17. Thermoluminescence of zircon: a kinetic model

    CERN Document Server

    Turkin, A A; Vainshtein, D I; Hartog, H W D

    2003-01-01

    The mineral zircon, ZrSiO sub 4 , belongs to a class of promising materials for geochronometry by means of thermoluminescence (TL) dating. The development of a reliable and reproducible method for TL dating with zircon requires detailed knowledge of the processes taking place during exposure to ionizing radiation, long-term storage, annealing at moderate temperatures and heating at a constant rate (TL measurements). To understand these processes one needs a kinetic model of TL. This paper is devoted to the construction of such a model. The goal is to study the qualitative behaviour of the system and to determine the parameters and processes controlling TL phenomena of zircon. The model considers the following processes: (i) Filling of electron and hole traps at the excitation stage as a function of the dose rate and the dose for both (low dose rate) natural and (high dose rate) laboratory irradiation. (ii) Time dependence of TL fading in samples irradiated under laboratory conditions. (iii) Short time anneali...

  18. Thermoluminescence analysis of irradiated oyster shells

    International Nuclear Information System (INIS)

    Cruz-Zaragoza, E.; Marcazzó, J.; Della Monaca, S.; Boniglia, C.; Gargiulo, R.; Bortolin, E.

    2012-01-01

    This paper reports the thermoluminescence (TL) analysis performed on the oyster shells powder. TL response of 60 Co gamma-rays irradiated samples were studied in the range from 80 Gy to 8 kGy doses. TL signal of irradiated shell powder was higher as compared to the unirradiated control samples, which allowed to identify the irradiated oysters. Results show that the oyster shells have good TL properties and can be useful for the identification of irradiated seafood as well as for the evaluation of the treatment dose. - Highlights: ► TL properties of irradiated oyster shell powder were studied. ► The SEM analysis shows that several elements are present in oyster shell powder. ► Calcite is the main component in the samples and β-calcite is also present. ► Following the European Standard EN 1788, the irradiated oyster can be identified. ► Determination of absorbed dose is possible by performing a preheat treatment.

  19. Thermoluminescent and impedimetric studies on irradiated foodstuffs

    International Nuclear Information System (INIS)

    Mamoon, A.M.

    2000-01-01

    Several brands of different spices and milk powders were irradiated with relatively high doses of gamma radiation. Glow curves were produced upon heating these irradiated foodstuffs only. Study of the obtained spices glow curves revealed that the magnitude of these curves depends upon the dose received while the shape of the curves remains generally the same for the different doses and for the different spices. Previous studies had shown that the obtained thermoluminescence (TL) is due to dust particles carried by the spices. The TL studies show, furthermore, that different brands of the same spice are apparently contaminated with different amounts of dust or soil. The obtained TL from irradiated milk powders is apparently due to its mineral content. Different milk powders gave TL curves of different magnitudes for the same dose depending upon the milk brand. Impedimetric studies carried out irradiated potatoes show changes in impedance amplitude and phase angle. The results support earlier work on the use of TL to differentiate between irradiated and control foodstuffs, to assess the extent of spices contamination with soil-which perhaps reflects hygienic care-and that impedimetric measurements can distinguish irradiated from control potatoes

  20. Thermoluminescence properties of AlN ceramics

    DEFF Research Database (Denmark)

    Trinkler, L.; Christensen, P.; Agersnap Larsen, N.

    1998-01-01

    The paper describes thermoluminescence (TL) properties of AlN:Y2O3 ceramics irradiated with ionising radiation. A high TL sensitivity of AlN:Y2O3 ceramics to radiation encouraged a study of the AlN ceramics for application as a dosimetric material. The paper presents experimental data on: glow...... curve, emission spectrum, dose response, energy dependence, influence of heating rate and fading rate. The measured TL characteristics were compared with those of well-known, widely used TLDs, i.e. LiF:Mg,Ti, LiF:Mg,Cu,P and Al2O3:C. It is concluded that AlN:Y2O3 ceramics showing a radiation sensitivity...... which is approximately 50 times greater than that of LiF:Mg,Ti is an interesting dosimetry material; however due to a high fading rate of the TL of AlN:Y2O3 on storage at room temperature, a further development of the material for improving the fading characteristics is needed for its application...

  1. Evaluation of environmental monitoring thermoluminescent dosimeter locations

    International Nuclear Information System (INIS)

    Kinnison, R.

    1992-12-01

    Geostatistics, particularly kriging, has been used to assess the adequacy of the existing NTS thermoluminescent dosimeter network for determination of environmental exposure levels. (Kriging is a linear estimation method that results in contour plots of both the pattern of the estimated gamma radiation over the area of measurements and also of the standard deviations of the estimated exposure levels.) Even though the network was not designed as an environmental monitoring network, ft adequately serves this function in the region of Pahute and Rainier Mesas.. The Yucca Flat network is adequate only if a reasonable definition of environmental exposure levels is required; R is not adequate for environmental monitoring in Yucca Flat if a coefficient of variation of 10 percent or less is chosen as the criterion for network design. A revision of the Yucca Flat network design should be based on a square grid pattern with nodes 5000 feet (about one mile) apart, if a 10 percent coefficient of variation criterion is adopted. There were insufficient data for southern and western sections of the NTS to perform the geostatistical analysis. A very significant finding was that a single network design cannot be used for the entire NTS, because different areas have different variograms. Before any design can be finalized, the NTS management must specify the exposure unit area and coefficient of variation that are to be used as design criteria

  2. Competition between excitation and bleaching of thermoluminescence

    International Nuclear Information System (INIS)

    Chen, R.; Hornyak, W.F.

    1990-01-01

    The bleaching of thermoluminescence (TL) yield to a residual value by light is explained, at least in some cases, to be due to an equilibrium between excitation and de-excitation by the illuminating light. Kinetic differential equations are given governing the process for the simple case of a single trapping state for electrons and a single variety of hole recombination centre. The equations are solved numerically for chosen sets of the relevant parameters starting either from empty traps and centres or from highly populated ones. In agreement with experimental results, the numerical computation predicts that after a long enough illumination the process of filling of the traps converges to the same equilibrium value as that produced by bleaching. It is also found that the equilibrium value is independent of the intensity, though, of course, this is approached faster with more intense light. The computed dependencies of the filling of trapping states as a function of illumination time are shown. The final equilibrium value for the filling of trapping states can also be evaluated analytically for any set of given parameters; these compare very favourably with the calculated results. The change of the results with the variation of the relevant parameters is discussed. (author)

  3. Thermoluminescence of calcium-based phosphors

    International Nuclear Information System (INIS)

    Sunta, C.M.

    1985-01-01

    The paper reviews the thermoluminescence (TL) properties of calcium fluoride, calcium sulphate and calcium carbonate phosphors. In the case of the calcium fluoride mineral phosphor the main emitter of TL is the cerium impurity. Based on the TL emission spectra, two types of Ce 3+ centres can be easily distinguished; those associated with O 2- compensating ion and those which have either no local compensators or are associated with F - interstitial ions at the adjacent vacant body centre position. The spectra undergo remarkable changes at high doses. Such changes are associated with the probabilities of charge trapping at different types of traps and also with the probabilities of recombination at different types of luminescent centres. Some of the traps and recombination centres are spatially associated while others are distributed randomly. In calcium carbonate mineral, Mn 2+ is invariably the emitting impurity. Mn 2+ can be used as an efficient dopant for TL emission in all the three calcium based TL phosphors. A co-dopant like Ce 3+ intensifies the luminescence yield from Mn 2+ . Models of different types of electron and hole trapping centres are given. (author)

  4. Thermoluminescence dating of Brazilian indigenous ceramics

    International Nuclear Information System (INIS)

    Farias, T. M. B.; Gennari, R. F.; Etchevarne, C.; Watanabe, S.

    2009-01-01

    Two indigenous ceramics fragments, one from Lagoa Queimada (LQ) and another from Barra dos Negros (BN), both sites located on Bahia state (Brazil), were dated by thermoluminescence (TL) method. Each fragment was physically prepared and divided into two fractions, one was used for TL measurement and the other for annual dose determination. The TL fraction was chemically treated, divided in sub samples and irradiated with several doses. The plot extrapolation from TL intensities as function of radiation dose enabled the determination of the accumulated dose (D ac ), 3.99 Gy and 1.88 Gy for LQ and BN, respectively. The annual dose was obtained through the uranium, thorium and potassium determination by ICP-MS. The annual doses (D an) obtained were 2.86 and 2.26 mGy/year. The estimated ages were ∼1375 and 709 y for BN and LQ ceramics, respectively. The ages agreed with the archaeologists' estimation for the Aratu and Tupi tradition periods, respectively. (authors)

  5. A technique for the assessment of the masses of residual plutonium in gloveboxes using thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    Day, B.; Godward, D.F.

    1979-01-01

    A means of measuring the mass of residual plutonium in gloveboxes in the size range 1 to 10 m 3 has been developed using multiple thermoluminescent detectors. By optimising the location and the number of detectors, and by using suitable filtration, the mean response from them has been made insensitive to the distribution and the composition of the plutonium. It is possible to detect 10 g of plutonium in the largest glovebox considered. The measurement and mass estimation processes have been reduced to simple operations which can be carried out by skilled industrial staff. The routine application of the technique has been arranged to minimise disturbance to be production work going on in the gloveboxes by making unattended measurements during silent hours

  6. Routine sputum culture

    Science.gov (United States)

    Sputum culture ... There, it is placed in a special dish (culture). It is then watched to see if bacteria ... Elsevier; 2018:chap 36. Chernecky CC, Berger BJ. Culture, routine. In: Chernecky CC, Berger BJ, eds. Laboratory ...

  7. Investigations on low temperature thermoluminescence centres in quartz

    International Nuclear Information System (INIS)

    Bernhardt, H.

    1984-01-01

    The present paper will help to understand the often investigated process of thermoluminescence of quartz which is of high complexity. A lot of traps exist in quartz crystals which compete with each other with respect to the trapping of charge carriers during the X-ray treatment. That is why a variety of processes takes place after X-irradiation at liquid nitrogen temperature (LNT) of quartz which complicate the phenomenology of low temperature thermoluminescence. This competition in the trapping process leads to the so-called 'sensibilization' or 'desensibilization' effects of thermoluminescence, respectively, which are described in this paper for the first time. This effect means the dependence of the LNT thermoluminescence intensity on a pre-irradiation dose applied at room temperature (RT). The influence of this pre-irradiation is understood assuming the saturation of competitive traps. This favours an enhanced trapping of charge carriers at LNT-(shallow) traps instead of the preferential trapping on the deep traps in the case of X-ray treatment of the as-grown crystal at LNT. To get the afore mentioned model we take into account not only thermoluminescence but also coloration, ir- and vuv-absorption measurements. (author)

  8. Obtention of a thermoluminescent material for dosimetry of ionizing radiation

    International Nuclear Information System (INIS)

    Gonzalez M, P.R.

    1990-01-01

    The thermoluminescent dosemeters are small crystals which suffer changes in their structure by the radiation effect, being displaced the electrons toward higher energy levels. On heating the previously irradiated crystals, the electrons come back to their base state emitting light photons. The light quantity emitted is proportional to the received radiation dose. The light quantity emitted is proportional to the received radiation dose. The lithium fluoride is one of the thermoluminescent materials considered as tissue equivalents by having a low effective atomic number (Z ef ). At present, the more used commercial product used of this type is the TLD-100*. In this work the obtained results in the preparation of the lithium fluoride thermoluminescent material are presented. This is activated with magnesium (Mg) and titanium (Ti), which we have labelled as: LiF: Mg, Ti. The results from the tests performed for verifying his thermoluminescent properties are presented too, as powder form as in pellets form. These tests were performed in simultaneous form with TLD-100 samples, which is considered as reference. The LiF: Mg, Ti thermoluminescent material manufactured in the ININ presents similar dosimetric characteristics to those ones of the TLD-100. Therefore being able to replace the imported dosemeters. * (TLD-100 is a commercial trademark registered by Harshaw/Filtrol (US) for LiF: Mg, Ti Tl dosemeters) (Author)

  9. Consuming technologies - developing routines

    DEFF Research Database (Denmark)

    Gram-Hanssen, Kirsten

    2008-01-01

    technologies and in this article these processes will be investigated from three different perspectives: an historical perspective of how new technologies have entered homes, a consumer perspective of how both houses and new technologies are purchased and finally, as the primary part of the article, a user...... perspective of how routines develop while these technologies are being used. In the conclusion these insights are discussed in relation to possible ways of influencing routines....

  10. Global Cooling: Effect of Urban Albedo on Global Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Akbari, Hashem; Menon, Surabi; Rosenfeld, Arthur

    2007-05-22

    In many urban areas, pavements and roofs constitute over 60% of urban surfaces (roof 20-25%, pavements about 40%). The roof and the pavement albedo can be increased by about 0.25 and 0.10, respectively, resulting in a net albedo increase for urban areas of about 0.1. Many studies have demonstrated building cooling-energy savings in excess of 20% upon raising roof reflectivity from an existing 10-20% to about 60%. We estimate U.S. potential savings in excess of $1 billion (B) per year in net annual energy bills. Increasing albedo of urban surfaces can reduce the summertime urban temperature and improve the urban air quality. Increasing the urban albedo has the added benefit of reflecting more of the incoming global solar radiation and countering the effect of global warming. We estimate that increasing albedo of urban areas by 0.1 results in an increase of 3 x 10{sup -4} in Earth albedo. Using a simple global model, the change in air temperature in lowest 1.8 km of the atmosphere is estimated at 0.01K. Modelers predict a warming of about 3K in the next 60 years (0.05K/year). Change of 0.1 in urban albedo will result in 0.01K global cooling, a delay of {approx}0.2 years in global warming. This 0.2 years delay in global warming is equivalent to 10 Gt reduction in CO2 emissions.

  11. Laser readable thermoluminescent radiation dosimeters and methods for producing thereof

    International Nuclear Information System (INIS)

    Braunlich, P.F.; Tetzlaff, W.

    1989-01-01

    Thin layer thermoluminescent radiation dosimeters for use in laser readable dosimetry systems, and methods of fabricating such thin layer dosimeters are disclosed. The thin layer thermoluminescent radiation dosimeters include a thin substrate made from glass or other inorganic materials capable of withstanding high temperatures and high heating rates. A thin layer of a thermoluminescent phosphor material is heat bonded to the substrate using an inorganic binder such as glass. The dosimeters can be mounted in frames and cases for ease in handling. Methods of the invention include mixing a suitable phosphor composition and binder, both being in particulate or granular form. The mixture is then deposited onto a substrate such as by using mask printing techniques. The dosimeters are thereafter heated to fuse and bond the binder and phosphor to the substrate. 34 figs

  12. Effect of particle size on the thermoluminescent response of hydroxyapatite

    International Nuclear Information System (INIS)

    Barrera V, A.; Zarate M, J.; Contreras, M. E.; Rivera M, T.

    2016-10-01

    We present the study of the structural characterization and the thermoluminescent response of the hydroxyapatite as a function of the calcination temperature and the effect of the particle size. For precipitation synthesis, calcium nitrate (Ca(NO_3)_2 and dibasic ammonium phosphate ((NH_4)_2HPO_4) were used as precursors and ammonium hydroxide (NH_4OH) as a ph controlling agent. The characterization of the samples was carried out by the techniques of X-ray diffraction, scanning electron microscopy and infrared spectroscopy. The powders obtained are composed of hydroxyapatite, with a different degree of dehydroxylation. The thermoluminescent characterization indicates that at higher calcination temperature there is a higher thermoluminescent response, the calcined powders at 1300 degrees Celsius show a very well defined brightness curve with a higher intensity, with its maximum intensity located at a temperature of 210 degrees Celsius, which indicates that this material can be used as a dosimeter. (Author)

  13. Radiation induced defects and thermoluminescence mechanism in aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    Atobe, K.; Kobayashi, T.; Awata, T. [Naruto Univ. of Education, Tokushima (Japan); Okada, M. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Nakagawa, M. [Kagawa Univ., Faculty of Education, Takamatsu, Kagawa (Japan)

    2001-01-01

    The thermoluminescence of the irradiated aluminum oxides were measured to study the radiation induced defects and their behaviors. Neutron and {gamma}-ray irradiation were performed for a shingle crystal of the high purity aluminum oxide. The thermoluminescence glow curve and its activation energy were measured. The spectroscopy measurement on the thermoluminescence and the absorption are also carried out. The observed 430 and 340 nm peaks are discussed relating to the F{sup +} and F centers, respectively. Activation state of the F center transits to 3P state through 1P state by emitting phonons. Trapped electron on 3P state emits phonon of 2.9 eV (430 nm) during transition to the ground state. The above reaction can be written by the equation. F{sup +} + e {yields} (F){sup *} {yields} F + h{nu}(2.9 eV, 470 nm). (Katsuta, H.)

  14. Thermoluminescence of Zn O thin films deposited by chemical bath

    International Nuclear Information System (INIS)

    Camacho A, M. C.; Cruz V, C.; Bernal H, R.; Berman M, D.; Castano M, V. M.

    2015-10-01

    Full text: Zn O films on Si were synthesized using a deposition method by chemical bath and thermally treated at 900 degrees C for 12 h in air. The morphological characterization by scanning electron microscopy reveals that uniform films were obtained. To investigate the thermoluminescent properties of the films were exposed to irradiation with beta particles with doses in the range from 0.5 to 128 Gy. The brightness curves obtained using a heating rate of 5 degrees C have two peaks, one at 124 and another at 270 degrees C, and a linear dependence of the integrated thermoluminescence as a function of dose. The second maximum reveals the existence of localized trapping states of potential utility in thermoluminescent dosimetry. (Author)

  15. A Continental United States High Resolution NLCD Land Cover – MODIS Albedo Database to Examine Albedo and Land Cover Change Relationships

    Science.gov (United States)

    Surface albedo influences climate by affecting the amount of solar radiation that is reflected at the Earth’s surface, and surface albedo is, in turn, affected by land cover. General Circulation Models typically use modeled or prescribed albedo to assess the influence of land co...

  16. Acceptance Testing of Thermoluminescent Dosimeter Holders.

    Science.gov (United States)

    Romanyukha, Alexander; Grypp, Matthew D; Sharp, Thad J; DiRito, John N; Nelson, Martin E; Mavrogianis, Stanley T; Torres, Jeancarlo; Benevides, Luis A

    2018-05-01

    The U.S. Navy uses the Harshaw 8840/8841 dosimetric (DT-702/PD) system, which employs LiF:Mg,Cu,P thermoluminescent dosimeters (TLDs), developed and produced by Thermo Fisher Scientific (TFS). The dosimeter consists of four LiF:Mg,Cu,P elements, mounted in Teflon® on an aluminum card and placed in a plastic holder. The holder contains a unique filter for each chip made of copper, acrylonitrile butadiene styrene (ABS), Mylar®, and tin. For accredited dosimetry labs, the ISO/IEC 17025:2005(E) requires an acceptance procedure for all new equipment. The Naval Dosimetry Center (NDC) has developed and tested a new non-destructive procedure, which enables the verification and the evaluation of embedded filters in the holders. Testing is based on attenuation measurements of low-energy radiation transmitted through each filter in a representative sample group of holders to verify that the correct filter type and thickness are present. The measured response ratios are then compared with the expected response ratios. In addition, each element's measured response is compared to the mean response of the group. The test was designed and tested to identify significant nonconformities, such as missing copper or tin filters, double copper or double tin filters, or other nonconformities that may impact TLD response ratios. During the implementation of the developed procedure, testing revealed a holder with a double copper filter. To complete the evaluation, the impact of the nonconformities on proficiency testing was examined. The evaluation revealed failures in proficiency testing categories III and IV when these dosimeters were irradiated to high-energy betas.

  17. Thermoluminescence of meteorites and their orbits

    International Nuclear Information System (INIS)

    Melcher, C.L.

    1981-01-01

    The thermolunimescence (TL) levels of 45 ordinary chondrites were measured to obtain information about the meteorite orbits. The low-temperature TL reaches equilibrium while the meteorite is in space and reflects the temperature of the meteorite at perihelion. Samples of Pribram, Lost City, and Innisfree, whose orbits are accurately known, were used as control samples. The TL levels in 40 out of 42 meteorites are similar to the three control samples, indicating that the vast majority of ordinary chondrites that survive atmospheric entry have perihelia similar to three known orbits, i.e., in the range 0.8-1 AU. The effects of albedo and rotation are also considered. A simple model indicates that temperature gradients of 1-2 0 K/cm are possible in slowly rotating meteoroids and such a temperature gradient is consistent with the unusually large TL gradient measured in the Farmville meteorite. Since slow rotation rates are improbable, other possibilities are examined but no satisfactory explanation has been found. The TL level measured in the Malakal meteorite is two orders of magnitude lower than control samples and is best explained by thermal draining due to solar heating in an orbit with a small perihelion distance. The perihelion is estimated to be approx. 0.5-0.6 AU. (orig.)

  18. Relating black carbon content to reduction of snow albedo

    Science.gov (United States)

    Brandt, R. E.; Warren, S. G.; Clarke, A. D.

    2011-12-01

    In remote snow of the Northern Hemisphere, the levels of soot pollution are in the parts-per-billion (ppb) range, where the effect on albedo is at the level of a few percent. A reduction of albedo by 1-2% is significant for climate but is difficult to detect experimentally, because snow albedo depends on several other variables. In our work to quantify the climatic effect of black carbon (BC) in snow, we therefore do not directly measure the albedo reduction. Instead, we use a two-step procedure: (1) We collect snow samples, melt and filter them, and analyze the filters spectrophotometrically for BC concentration. (2) We use the BC amount from the filter measurement, together with snow grain size, in a radiative transfer model to compute the albedo reduction. Our radiative transfer model uses the discrete ordinates algorithm DISORT 2.0. We have chosen a representative BC size distribution and optical constants, and have incorporated those of mineral dust as well. While a given mass of BC causes over an order of magnitude more snow albedo reduction compared to dust, a snowpack containing dust mutes the albedo-reducing effect of BC. Because the computed reduction of snow albedo is model-based, it requires experimental verification. We doubt that direct measurement of albedo-reduction will be feasible in nature, because of the vertical variation of both snow grain size and soot content, and because the natural soot content is small. We conclude that what is needed is an artificial snowpack, with uniform grain size and large uniform soot content (ppm not ppb), to produce a large signal on albedo. We have chosen to pursue this experiment outdoors rather than in the laboratory, for the following reasons: (1) The snowpack in the field of view is uniformly illuminated if the source of radiation is the Sun. (2) Visible radiation penetrates into the snow, so photons emerge horizontally distant from where they entered. In the limited width of a laboratory snowpack, radiation

  19. Higher albedos and size distribution of large transneptunian objects

    Science.gov (United States)

    Lykawka, Patryk Sofia; Mukai, Tadashi

    2005-11-01

    Transneptunian objects (TNOs) orbit beyond Neptune and do offer important clues about the formation of our solar system. Although observations have been increasing the number of discovered TNOs and improving their orbital elements, very little is known about elementary physical properties such as sizes, albedos and compositions. Due to TNOs large distances (>40 AU) and observational limitations, reliable physical information can be obtained only from brighter objects (supposedly larger bodies). According to size and albedo measurements available, it is evident the traditionally assumed albedo p=0.04 cannot hold for all TNOs, especially those with approximately absolute magnitudes H⩽5.5. That is, the largest TNOs possess higher albedos (generally >0.04) that strongly appear to increase as a function of size. Using a compilation of published data, we derived empirical relations which can provide estimations of diameters and albedos as a function of absolute magnitude. Calculations result in more accurate size/albedo estimations for TNOs with H⩽5.5 than just assuming p=0.04. Nevertheless, considering low statistics, the value p=0.04 sounds still convenient for H>5.5 non-binary TNOs as a group. We also discuss about physical processes (e.g., collisions, intrinsic activity and the presence of tenuous atmospheres) responsible for the increase of albedo among large bodies. Currently, all big TNOs (>700 km) would be capable to sustain thin atmospheres or icy frosts composed of CH 4, CO or N 2 even for body bulk densities as low as 0.5 g cm -3. A size-dependent albedo has important consequences for the TNOs size distribution, cumulative luminosity function and total mass estimations. According to our analysis, the latter can be reduced up to 50% if higher albedos are common among large bodies. Lastly, by analyzing orbital properties of classical TNOs ( 42AUbodies. For both populations, distinct absolute magnitude distributions are maximized for an inclination threshold

  20. Study of a new glass matrix by the thermoluminescence technique

    International Nuclear Information System (INIS)

    Ferreira, Pamela Z.; Vedovato, Uly P.; Cunha, Diego M. da; Dantas, Noelio O.; Silva, Anielle C.A.; Neves, Lucio P.; Perini, Ana P.; Carrera, Betzabel N.S.; Watanabe, Shigueo

    2015-01-01

    The thermoluminescence technique is widely used for both personal and for high-dose dosimetry. In this work, the thermoluminescence technique was utilized to study a new glass matrix, with nominal composition of 20Li 2 CO 3 .10Al 2 O 3 .20BaO.50B 2 O 3 (mol%), irradiated with different doses in a 60 Co source. The glow curves and the dose-response curve were obtained for radiation doses between 50 Gy and 900 Gy. The results showed that this new glass matrix presents potential use in high-dose dosimetry. (author)

  1. Irradiated black pepper identification based on thermoluminescence of silicate minerals

    International Nuclear Information System (INIS)

    Faycal Kharfi; Randa Ketfi

    2018-01-01

    In this work we have successfully implemented thermoluminescence TL method for irradiated food identification. First tests are performed on Indian black pepper and show promising results to extend the proposed method to many other foods. The X-ray diffraction (XRD) shows that SiO 2 (p3 2 21) is the main component of the separated mineral phase. A saturation dose of ∼ 100 Gy is determined for this pepper above which all thermoluminescent centers of the quartz are activated. Thus, above this threshold dose, only the pepper irradiation will be confirmed but no accuracy on the exact dose received. (author)

  2. Thermoluminescence studies on plant seeds of different radiosensitivity

    International Nuclear Information System (INIS)

    Yamaguchi, Hikoyuki; Eguchi, Hoshio; Koizumi, Yoshinobu.

    1975-01-01

    The thermoluminescence was found when the pulverized powders from the whole seeds of six plant species or the hypocotyls from the seeds of five soybean varieties were irradiated at a liquid nitrogen temperature with gamma-rays. The spectra of luminescence emitted, the light peak temperature, the decaying after irradiation and the dose relationship of luminescence were determined. A high yield of the rapidly-decaying luminescence occurred in the more radiosensitive variety when irradiated with relatively lower doses. The very drastic decrease of the thermoluminescence was observed in the samples irradiated at room temperature prior to the exposure at 77 0 K. (auth.)

  3. Size and Albedo of Irregular Saturnian Satellites from Spitzer Observations

    Science.gov (United States)

    Mueller, Michael; Grav, T.; Trilling, D.; Stansberry, J.; Sykes, M.

    2008-09-01

    Using MIPS onboard the Spitzer Space Telescope, we observed the thermal emission (24 and, for some targets, 70 um) of eight irregular satellites of Saturn: Albiorix, Siarnaq, Paaliaq, Kiviuq, Ijiraq, Tarvos, Erriapus, and Ymir. We determined the size and albedo of all targets. An analysis of archived MIPS observations of Phoebe reproduces Cassini results very accurately, thereby validating our method. For all targets, the geometric albedo is found to be low, probably below 10% and clearly below 15%. Irregular satellites are much darker than the large regular satellites. Their albedo is, however, quite similar to that of small bodies in the outer Solar System (such as cometary nuclei, Jupiter Trojans, or TNOs). This is consistent with color measurements as well as dynamical considerations which suggest a common origin of the said populations. There appear to be significant object-to-object albedo differences. Similar albedos found for some members of dynamical clusters support the idea that they may have originated in the breakup of a parent body. For three satellites, thermal data at two wavelengths are available, enabling us to constrain their thermal properties. Sub-solar temperatures are similar to that found from Cassini's Phoebe fly-by. This suggests a rather low thermal inertia, as expected for regolith-covered objects. This work is based on observations made with the Spitzer Space Telescope, which is operated by JPL under a contract with NASA. Support for this work was provided by NASA.

  4. Clear-sky narrowband albedos derived from VIRS and MODIS

    Science.gov (United States)

    Sun-Mack, Sunny; Minnis, Patrick; Chen, Yan; Arduini, Robert F.

    2004-02-01

    The Clouds and Earth"s Radiant Energy System (CERES) project is using multispectral imagers, the Visible Infrared Scanner (VIRS) on the tropical Rainfall Measuring Mission (TRMM) satellite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra, operating since spring 2000, and Aqua, operating since summer 2002, to provide cloud and clear-sky properties at various wavelengths. This paper presents the preliminary results of an analysis of the CERES clear-sky reflectances to derive a set top-of-atmosphere clear sky albedo for 0.65, 0.86, 1.6, 2.13 μm, for all major surface types using the combined MODIS and VIRS datasets. The variability of snow albedo with surface type is examined using MODIS data. Snow albedo was found to depend on the vertical structure of the vegetation. At visible wavelengths, it is least for forested areas and greatest for smooth desert and tundra surfaces. At 1.6 and 2.1-μm, the snow albedos are relatively insensitive to the underlying surface because snow decreases the reflectance. Additional analyses using all of the MODIS results will provide albedo models that should be valuable for many remote sensing, simulation and radiation budget studies.

  5. Tundra vegetation effects on pan-Arctic albedo

    International Nuclear Information System (INIS)

    Loranty, Michael M; Goetz, Scott J; Beck, Pieter S A

    2011-01-01

    Recent field experiments in tundra ecosystems describe how increased shrub cover reduces winter albedo, and how subsequent changes in surface net radiation lead to altered rates of snowmelt. These findings imply that tundra vegetation change will alter regional energy budgets, but to date the effects have not been documented at regional or greater scales. Using satellite observations and a pan-Arctic vegetation map, we examined the effects of shrub vegetation on albedo across the terrestrial Arctic. We included vegetation classes dominated by low shrubs, dwarf shrubs, tussock-dominated graminoid tundra, and non-tussock graminoid tundra. Each class was further stratified by bioclimate subzones. Low-shrub tundra had higher normalized difference vegetation index values and earlier albedo decline in spring than dwarf-shrub tundra, but for tussock tundra, spring albedo declined earlier than for low-shrub tundra. Our results illustrate how relatively small changes in vegetation properties result in differences in albedo dynamics, regardless of shrub growth, that may lead to differences in net radiation upwards of 50 W m -2 at weekly time scales. Further, our findings imply that changes to the terrestrial Arctic energy budget during this important seasonal transition are under way regardless of whether recent satellite observed productivity trends are the result of shrub expansion. We conclude that a better understanding of changes in vegetation productivity and distribution in Arctic tundra is essential for accurately quantifying and predicting carbon and energy fluxes and associated climate feedbacks.

  6. Matrix albedo for discrete ordinates infinite-medium boundary condition

    International Nuclear Information System (INIS)

    Mathews, K.; Dishaw, J.

    2007-01-01

    Discrete ordinates problems with an infinite exterior medium (reflector) can be more efficiently computed by eliminating grid cells in the exterior medium and applying a matrix albedo boundary condition. The albedo matrix is a discretized bidirectional reflection distribution function (BRDF) that accounts for the angular quadrature set, spatial quadrature method, and spatial grid that would have been used to model a portion of the exterior medium. The method is exact in slab geometry, and could be used as an approximation in multiple dimensions or curvilinear coordinates. We present an adequate method for computing albedo matrices and demonstrate their use in verifying a discrete ordinates code in slab geometry by comparison with Ganapol's infinite medium semi-analytic TIEL benchmark. With sufficient resolution in the spatial and angular grids and iteration tolerance to yield solutions converged to 6 digits, the conventional (scalar) albedo boundary condition yielded 2-digit accuracy at the boundary, but the matrix albedo solution reproduced the benchmark scalar flux at the boundary to all 6 digits. (authors)

  7. MORSE/STORM: A generalized albedo option for Monte Carlo calculations

    International Nuclear Information System (INIS)

    Gomes, I.C.; Stevens, P.N.

    1991-09-01

    The advisability of using the albedo procedure for the Monte Carlo solution of deep penetration shielding problems that have ducts and other penetrations has been investigated. The use of albedo data can dramatically improve the computational efficiency of certain Monte Carlo calculations. However, the accuracy of these results may be unacceptable because of lost information during the albedo event and serious errors in the available differential albedo data. This study was done to evaluate and appropriately modify the MORSE/BREESE package, to develop new methods for generating the required albedo data, and to extend the adjoint capability to the albedo-modified calculations. Major modifications to MORSE/BREESE include an option to save for further use information that would be lost at the albedo event, an option to displace the point of emergence during an albedo event, and an option to use spatially dependent albedo data for both forward and adjoint calculations, which includes the point of emergence as a new random variable to be selected during an albedo event. The theoretical basis for using TORT-generated forward albedo information to produce adjuncton albedos was derived. The MORSE/STORM package was developed to perform both forward and adjoint modes of analysis using spatially dependent albedo data. Results obtained with MORSE/STORM for both forward and adjoint modes were compared with benchmark solutions. Excellent agreement and improved computational efficiency were achieved, demonstrating the full utilization of the albedo option in the MORSE code. 7 refs., 17 figs., 15 tabs

  8. A Multisensor Approach to Global Retrievals of Land Surface Albedo

    Directory of Open Access Journals (Sweden)

    Aku Riihelä

    2018-05-01

    Full Text Available Satellite-based retrievals offer the most cost-effective way to comprehensively map the surface albedo of the Earth, a key variable for understanding the dynamics of radiative energy interactions in the atmosphere-surface system. Surface albedo retrievals have commonly been designed separately for each different spaceborne optical imager. Here, we introduce a novel type of processing framework that combines the data from two polar-orbiting optical imager families, the Advanced Very High-Resolution Radiometer (AVHRR and Moderate Resolution Imaging Spectroradiometer (MODIS. The goal of the paper is to demonstrate that multisensor albedo retrievals can provide a significant reduction in the sampling time required for a robust and comprehensive surface albedo retrieval, without a major degradation in retrieval accuracy, as compared to state-of-the-art single-sensor retrievals. We evaluated the multisensor retrievals against reference in situ albedo measurements and compare them with existing datasets. The results show that global land surface albedo retrievals with a sampling period of 10 days can offer near-complete spatial coverage, with a retrieval bias mostly comparable to existing single sensor datasets, except for bright surfaces (deserts and snow where the retrieval framework shows degraded performance because of atmospheric correction design compromises. A level difference is found between the single sensor datasets and the demonstrator developed here, pointing towards a need for further work in the atmospheric correction, particularly over bright surfaces, and inter-sensor radiance homogenization. The introduced framework is expandable to include other sensors in the future.

  9. Diurnal variations in the UV albedo of arctic snow

    Directory of Open Access Journals (Sweden)

    O. Meinander

    2008-11-01

    Full Text Available The relevance of snow for climate studies is based on its physical properties, such as high surface reflectivity. Surface ultraviolet (UV albedo is an essential parameter for various applications based on radiative transfer modeling. Here, new continuous measurements of the local UV albedo of natural Arctic snow were made at Sodankylä (67°22'N, 26°39'E, 179 m a.s.l. during the spring of 2007. The data were logged at 1-min intervals. The accumulation of snow was up to 68 cm. The surface layer thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and 2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in the accumulation period, and from 0.5 to 0.7 during melting. During the snow melt period, under cases of an almost clear sky and variable cloudiness, an unexpected diurnal decrease of 0.05 in albedo soon after midday, and recovery thereafter, was detected. This diurnal decrease in albedo was found to be asymmetric with respect to solar midday, thus indicating a change in the properties of the snow. Independent UV albedo results with two different types of instruments confirm these findings. The measured temperature of the snow surface was below 0°C on the following mornings. Hence, the reversible diurnal change, evident for ~1–2 h, could be explained by the daily metamorphosis of the surface of the snowpack, in which the temperature of the surface increases, melting some of the snow to liquid water, after which the surface freezes again.

  10. Chronology of Chichen Izta, evidences by thermoluminescence

    International Nuclear Information System (INIS)

    Ramirez, A.; Schaaf, P.; Gonzalez, P.R.; Chung, H.

    2002-01-01

    The establishment of the chronology of Chichen Itza is argued by its stylistic evocations, architectural and iconographical as well as its history related in the sources, as the Chilam Balam, where is named the arrival of foreign tribes as the Xiu and the Itzaes and its settlement in Chichen Itza as well as the return to its origin place. The material evidence of such transition is reflected in the ceramic change of the Pizarra Puuc to the Pizarra Chichen, however, in 13 stratigraphic wells realized in different points of Chichen Itza, it was not found evidence of the layer of the Pizarra Puuc period. In this work the obtained ages of dating by thermoluminescence (TL) are presented, of four samples of ceramics found in the different wells. When our results are compared with the estimated ages for the different groups of ceramics, it was observed that none of they corresponded to the Pizarra Puuc period. These results strenghten the observations realized during excavations, causing the suggestion of new inferences related to the Chichen Itza boom and its relationship with the Maya Classic Period. The used technique for the TL dating was that of fine grain. The interval of artificial dose, of beta radiation of Strontium 90 was between 2 and 30 Gy. The TL signal was obtained heating the samples at 10 C/s until reaching 500 C in the TL Daybreak reader equipment. In order to know the annual dose rate of concentration of potassium ( 40 K) by means of the microanalysis technique in the scanning electron microscope was determined, while the uranium content (2 38 U) and thorium ( 232 Th) were determined by means of the neutron activation analysis technique using the TRIGA Mark III nuclear reactor. The contribution of the gamma radiation of the soil as well as the contribution of the cosmic radiation was measured with TL dosemeters of CaSO 4 :Dy + Ptfe once the paleodose was known and the annual dose rate of each sample of its age was estimated. (Author)

  11. Improved streaming analysis technique: spherical harmonics expansion of albedo data

    International Nuclear Information System (INIS)

    Albert, T.E.; Simmons, G.L.

    1979-01-01

    An improved albedo scattering technique was implemented with a three-dimensional Monte Carlo transport code for use in analyzing radiation streaming problems. The improvement was based on a shifted spherical Harmonics expansion of the doubly differential albedo data base. The result of the improvement was a factor of 3 to 10 reduction in data storage requirements and approximately a factor of 3 to 6 increase in computational speed. Comparisons of results obtained using the technique with measurements are shown for neutron streaming in one- and two-legged square concrete ducts

  12. The high albedo of the hot Jupiter Kepler-7b

    DEFF Research Database (Denmark)

    Demory, B.-O.; Seager, S.; Madhusudhan, N.

    2011-01-01

    Hot Jupiters are expected to be dark from both observations (albedo upper limits) and theory (alkali metals and/or TiO and VO absorption). However, only a handful of hot Jupiters have been observed with high enough photometric precision at visible wavelengths to investigate these expectations....... The NASA Kepler mission provides a means to widen the sample and to assess the extent to which hot Jupiter albedos are low. We present a global analysis of Kepler-7 b based on Q0-Q4 data, published radial velocities, and asteroseismology constraints. We measure an occultation depth in the Kepler bandpass...

  13. Validation of response simulation methodology of Albedo dosemeter

    International Nuclear Information System (INIS)

    Freitas, B.M.; Silva, A.X. da

    2016-01-01

    The Instituto de Radioprotecao e Dosimetria developed and runs a neutron TLD albedo individual monitoring service. To optimize the dose calculation algorithm and to infer new calibration factors, the response of this dosemeter was simulated. In order to validate this employed methodology, it was applied in the simulation of the problem of the QUADOS (Quality Assurance of Computational Tools for Dosimetry) intercomparison, aimed to evaluate dosimetric problems, one being to calculate the response of a generic albedo dosemeter. The obtained results were compared with those of other modeling and the reference one, with good agreements. (author)

  14. NEOWISE REACTIVATION MISSION YEAR ONE: PRELIMINARY ASTEROID DIAMETERS AND ALBEDOS

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, C. R.; Cutri, R. M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Mainzer, A.; Masiero, J.; Bauer, J.; Kramer, E.; Sonnett, S.; Stevenson, R. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T. [Planetary Science Institute, Tucson, AZ (United States); Wright, E. L., E-mail: cnugent@ipac.caltech.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

    2015-12-01

    We present preliminary diameters and albedos for 7956 asteroids detected in the first year of the NEOWISE Reactivation mission. Of those, 201 are near-Earth asteroids and 7755 are Main Belt or Mars-crossing asteroids. 17% of these objects have not been previously characterized using the Near-Earth Object Wide-field Infrared Survey Explorer, or “NEOWISE” thermal measurements. Diameters are determined to an accuracy of ∼20% or better. If good-quality H magnitudes are available, albedos can be determined to within ∼40% or better.

  15. Ceres Photometry and Albedo from Dawn Framing Camera Images

    Science.gov (United States)

    Schröder, S. E.; Mottola, S.; Keller, H. U.; Li, J.-Y.; Matz, K.-D.; Otto, K.; Roatsch, T.; Stephan, K.; Raymond, C. A.; Russell, C. T.

    2015-10-01

    The Dawn spacecraft is in orbit around dwarf planet Ceres. The onboard Framing Camera (FC) [1] is mapping the surface through a clear filter and 7 narrow-band filters at various observational geometries. Generally, Ceres' appearance in these images is affected by shadows and shading, effects which become stronger for larger solar phase angles, obscuring the intrinsic reflective properties of the surface. By means of photometric modeling we attempt to remove these effects and reconstruct the surface albedo over the full visible wavelength range. Knowledge of the albedo distribution will contribute to our understanding of the physical nature and composition of the surface.

  16. Investigations on thermoluminescent dosimetry (TLD) with doped alumina ceramics

    International Nuclear Information System (INIS)

    Janas, R.; Huebner, K.

    1976-01-01

    Alumina ceramics doped and burned under various conditions have been investigated with regard to their suitability for thermoluminescent dosimetry. The production of ceramics is described. The properties essential for dosimetric purposes, such as glow curve, energy dose characteristics, fading, recoverability, lower detection limit and energy dependence, are indicated. The advantages and disadvantages of alumina ceramics are compared. (author)

  17. Thermoluminescence dating of late Devensian loesses in southern England

    International Nuclear Information System (INIS)

    Wintle, A.G.

    1981-01-01

    The results are reported of thermoluminescence dating of six relatively recent deposits of loess-like material from southern Britiain between the Scilly Isles and Kent. The dates have been obtained on the loess itself and confirm the ages as being late Devensian. (U.K.)

  18. Neutron dosimetry using activation of thermoluminescent CaSO 4

    Science.gov (United States)

    Azorín, Juan; Gutiérrez, Alicia

    1984-11-01

    Sulfur activation in calcium sulfate doped with dysprosium (CaSO 4:Dy) thermoluminescent powder, which is bound in pure sulfur, has been used to measure the fast neutron dose at the tangential beam port of a Triga Mark III reactor. After a post-irradiation time of 3 d, the dosimeters were annealed at 600°C for 30 min in order to erase all the thermoluminescence acquired during the irradiation. The dosimeters were then stored to allow self-irradiation by betas from 32P produced by sulfur activation. The thermoluminescent signal accumulated during a post-irradiation time of 20 d due to a neutron fluence of 2.2 × 10 11 n/cm 2 was equivalent to an absorbed dose of 10 mGy of 60Co gamma rays. The thermoluminescence as a function of fast neutron dose fitted to a straight line on a log-log scale from 1 Gy to 10 4Gy.

  19. The thermoluminescence of carp otoliths: A fingerprint in ...

    African Journals Online (AJOL)

    This paper reports a pilot study on the thermoluminescence (TL) of carbonate minerals of carp otoliths from the heavily polluted Baiyangdian Lake (BYD) in Hebei Province and non-polluted Miyun Water Reservoir (MY) in Beijing Municipality of China. Analyses on trace elements of otoliths and water show that the heavy ...

  20. Thermically stimulated exoelectronic emissions and thermoluminescence of MgO

    International Nuclear Information System (INIS)

    Chubaci, J.F.D.

    1987-01-01

    In this work, studies were performed on the following topics: i) thermically stimulated exoelectronic emission (TSEE) in pure MgO single crystals ion implanted, submitted to thermal treatment with fast on slow cooling and water adsorption; ii) ultraviolet light effect on TSEE; iii) thermoluminescent emission; iv) crystallization of FeCoB amorphous alloys. (A.C.A.S.) [pt

  1. The thermoluminescence of carp otoliths: A fingerprint in ...

    African Journals Online (AJOL)

    use

    2011-12-14

    Dec 14, 2011 ... provide a quick and qualitative means for environmental assessments in lake pollution. Key words: Thermoluminescence, fish otolith, heavy-metal elements, lake, pollution. INTRODUCTION. Fish otoliths are widely .... cleaned HDPE plastic bottles that have been rinsed with sample three times prior to use.

  2. Application of numerical analysis methods to thermoluminescence dosimetry

    International Nuclear Information System (INIS)

    Gomez Ros, J. M.; Delgado, A.

    1989-01-01

    This report presents the application of numerical methods to thermoluminescence dosimetry (TLD), showing the advantages obtained over conventional evaluation systems. Different configurations of the analysis method are presented to operate in specific dosimetric applications of TLD, such as environmental monitoring and mailed dosimetry systems for quality assurance in radiotherapy facilities. (Author) 10 refs

  3. Kerma determination in air on mamma by thermoluminescence

    International Nuclear Information System (INIS)

    Palacios P, L. L.; Rivera M, T.

    2009-10-01

    In this work the experimental results of the entrance exposition are shown and Kerma in air [mGy] in mamma obtained by irradiation of accreditation phantom of American College of Radiology (ACR). The irradiations were realized in a conventional mammography equipment of Hospital Juarez in Mexico; the technique used during the irradiations was of automatic exposition; the thickness for the phantom ACR obtained by the technique were of 4.2 and 4.5 cm; the kilo voltage pick was of 24 kV p , the time and the milli amperage per second variable. The measuring of Kerma in air was obtained with thermoluminescent dosemeters of solid state, of nano particles of zirconium dioxide prepared by the precipitation method. The dosemeters were homogenized previously in low energies of X-rays that are those used for mammography. The thermoluminescent dosemeters of ZrO 2 were calibrated by means of an ionization chamber for different expositions. The calibration curve is reported for the exposition and Kerma in air against thermoluminescent intensity obtained by reading of thermoluminescent dosemeters of ZrO 2 , as well as the technique employee for the Kerma determination in air and entrance exposition in mamma. (Author)

  4. Development of a highly sensitive lithium fluoride thermoluminescence dosimeter

    International Nuclear Information System (INIS)

    Moraes da Silva, Teresinha de; Campos, Leticia Lucente

    1995-01-01

    In recent times, LiF: Mg, Cu, P thermoluminescent phosphor has been increasingly in use for radiation monitoring due its high sensitivity and ease of preparation. The Dosimetric Materials Production Laboratory of IPEN, (Nuclear Energy Institute) has developed a simple method to obtain high sensitivity LiF. The preparation method is described. (author). 4 refs., 1 fig., 1 tab

  5. Spatially-resolved thermoluminescence from snail opercula using an EMCCD

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Kook, Myung Ho; Stirling, R.J.

    2015-01-01

    In recent years opercula of the snail species Bithynia tentaculata have been shown to emit thermoluminescence (TL) signals that can be used to determine equivalent dose, and may be capable of dating events throughout the entire Quaternary period. Concentric growth lines are a notable feature of a...

  6. Deconvolution of the thermoluminescent emission curve. Second order kinetics

    International Nuclear Information System (INIS)

    Moreno y M, A.; Moreno B, A.

    1999-01-01

    In this work it is described the Randall and Wilkins second order kinetics in Microsoft Excel language, which allows its expression as the sum of Gaussian and the correction factors corresponding. These factors are obtained of the differences between the real thermoluminescent curve and the Gaussian proposed. The results obtained justify the Gaussian expression added to the correction factor. (Author)

  7. The thermoluminescent curve as parameter to compare archaeological ceramics

    International Nuclear Information System (INIS)

    Dominguez R, I.R.; Ramirez C, G.A.; Gonzalez M, P.R.; Mendoza A, D.; Martinez C, G.

    2006-01-01

    Most mineral materials, including the constituents of pottery, have the property of thermoluminescence (TL), where part of the energy from radioactive decay in the mineral is stored and later released as light upon strong heating. The intensity of emitted light as a function of temperature is the thermoluminescence glow curve. However, it is well-know the thermoluminescence glow curve form depends of several factors associates with the incident radiation and type of materials. Between the factors associated with the materials, it can be mentioned the quantity and type of crystalline phases, and quantity and type of impurities that they could be present in the material. That is to say, materials with different physicochemical characteristics will produce different thermoluminescence glow curve, although, they have been irradiated under the same conditions. In accordance with the above mentioned, it is possible to identified differences between pre hispanic ceramic belonging to a same site and other sites. In this work a discussion about advantages and disadvantages is presented. Some specific examples in ceramic artifacts belonging to the Matlatzinca and Teotihuacan cultures are included. (Author)

  8. Natural Thermoluminescence and the Terrestrial and Orbital Histories of Ordinary Chondrites

    Science.gov (United States)

    Akridge, Jannette Marie Cunningham

    The amount of stored thermoluminescence in a meteorite is a direct result of storage temperature and duration of radiation exposure. I have used these relationships to study the terrestrial and orbital histories of meteorites. The orbital history of a meteorite is investigated using the high temperature portion of the glow curve while the study of terrestrial histories requires the use of the low temperature region. The build-up and decay parameters for the high temperature region of the thermoluminescence glow-curve for Paragould, Lost City, Tilden, Chicora, Innisfree and Pribram have been determined. All of the samples reach saturation at 360 +/- 10 krad and have a RO value (the dose necessary to fill 63.2% of the total available traps) of 80 krad. There are four trap populations with average temperatures of 321 +/- 7.3°C, 367 +/- 5.8°C, 406 +/- 4.8°C, and 462 +/- 5.8°C and average E values of 1.27 +/- 0.02 eV, 1.38 +/- 0.04 eV, 1.45 +/- 0.01 eV, and 1.51 +/- 0.01 eV; and averages s values of 7.87 +/- 1.85 x 109 sec-1 , 9.89 +/- 7.30 x 109 sec-1, 5.95 +/- 1.66 x 109 sec-1, and 2.01 +/- 0.50 x 109 sec-1, respectively. Based on calculations using the above TL parameters, I argue that Pribram was exposed to a higher average dose rate in space than Lost City and Innisfree. It is also possible that Paragould and Tilden have perihelia similar to that of Pribram. If the albedo of the two meteorites is assumed to be similar to Pribram then the aphelion must have been less than 3.5 AU, but if their albedos were lower than Pribram's their aphelia could have been as much as 4.0 AU. Chicora probably had a perihelion similar to that of Lost City and Innisfree but its aphelion was probably less than that of Lost City. I have measured the natural TL in the ``drained zone'' of 15 meteorites. The data indicate that this technique could be used with greater accuracy than 36Cl to determine terrestrial ages of meteorites with ages <200 ka, after which TL equilibrium is reached

  9. Determination of trapping parameters of the high temperature thermoluminescence peak in equilibrated ordinary chondrites

    International Nuclear Information System (INIS)

    Akridge, Jannette M.C.; Benoit, Paul H.; Sears, Derek W.G.

    2001-01-01

    Most meteorites exhibit thermoluminescence (TL) that can be used to constrain their recent thermal and irradiation history, but quantitative conclusions require a knowledge of the detailed TL peak structure of the TL glow curve. We have determined TL peak parameters for the high temperature portion of the glow curve for six ordinary chondrites: Chicora (LL6); Innisfree (L5); Lost City (H5); Paragould (LL6); Pribram (H5); and Tilden (L6). The saturation dose for all these meteorites is approximately 3600 Gy. Published procedures were used to determine the number and temperatures of peaks in the high temperature (>570 K) portion of the glow curve and peak fitting was used to estimate TL trap parameters for each peak. These data were then tested and adjusted, if necessary, by comparing calculated decay results with TL glow curves for samples heated at ∼420 K for various times. We find evidence for four TL peaks in the high temperature portion of the glow curve, where trapping parameters vary slightly from meteorite to meteorite. For the Lost City meteorite, the TL peak temperatures (K), activation energies (E, eV), and Arrhenius factors (s, x 10 -9 s -1 ) are: 325, 1.26, 4.8; 360, 1.33, 3.88; 401, 1.44, 5.8; and 455, 1.5, 2.25, respectively. These data could be used to estimate dose rates for meteorites; however, the albedo values required for the calculation are not yet sufficiently known. However, terrestrial ages, or surface exposure ages, for meteorite finds from hot deserts like those in Australia or North Africa, can be estimated from these data

  10. Determination of trapping parameters of the high temperature thermoluminescence peak in equilibrated ordinary chondrites

    Energy Technology Data Exchange (ETDEWEB)

    Akridge, Jannette M.C.; Benoit, Paul H. E-mail: pbenoit@comp.uark.edu; Sears, Derek W.G

    2001-02-01

    Most meteorites exhibit thermoluminescence (TL) that can be used to constrain their recent thermal and irradiation history, but quantitative conclusions require a knowledge of the detailed TL peak structure of the TL glow curve. We have determined TL peak parameters for the high temperature portion of the glow curve for six ordinary chondrites: Chicora (LL6); Innisfree (L5); Lost City (H5); Paragould (LL6); Pribram (H5); and Tilden (L6). The saturation dose for all these meteorites is approximately 3600 Gy. Published procedures were used to determine the number and temperatures of peaks in the high temperature (>570 K) portion of the glow curve and peak fitting was used to estimate TL trap parameters for each peak. These data were then tested and adjusted, if necessary, by comparing calculated decay results with TL glow curves for samples heated at {approx}420 K for various times. We find evidence for four TL peaks in the high temperature portion of the glow curve, where trapping parameters vary slightly from meteorite to meteorite. For the Lost City meteorite, the TL peak temperatures (K), activation energies (E, eV), and Arrhenius factors (s, x 10{sup -9} s{sup -1}) are: 325, 1.26, 4.8; 360, 1.33, 3.88; 401, 1.44, 5.8; and 455, 1.5, 2.25, respectively. These data could be used to estimate dose rates for meteorites; however, the albedo values required for the calculation are not yet sufficiently known. However, terrestrial ages, or surface exposure ages, for meteorite finds from hot deserts like those in Australia or North Africa, can be estimated from these data.

  11. Validation of response simulation methodology of Albedo dosemeter; Validacao da metodologia de simulacao de resposta de dosimetro de Albedo

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, B.M.; Silva, A.X. da, E-mail: bfreitas@nuclear.ufrj.br [Coordenacao do Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Mauricio, C.L.P. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2016-07-01

    The Instituto de Radioprotecao e Dosimetria developed and runs a neutron TLD albedo individual monitoring service. To optimize the dose calculation algorithm and to infer new calibration factors, the response of this dosemeter was simulated. In order to validate this employed methodology, it was applied in the simulation of the problem of the QUADOS (Quality Assurance of Computational Tools for Dosimetry) intercomparison, aimed to evaluate dosimetric problems, one being to calculate the response of a generic albedo dosemeter. The obtained results were compared with those of other modeling and the reference one, with good agreements. (author)

  12. The retrieval of land surface albedo in rugged terrain

    NARCIS (Netherlands)

    Gao, B.; Jia, L.; Menenti, M.

    2012-01-01

    Land surface albedo may be derived from the satellite data through the estimation of a bidirectional reflectance distribution function (BRDF) model and angular integration. However many BRDF models do not consider explicitly the topography. In rugged terrain, the topography influences the observed

  13. Size and Albedo of Irregular Saturnian Satellites from Spitzer Observations

    NARCIS (Netherlands)

    Mueller, Michael; Grav, T.; Trilling, D.; Stansberry, J.; Sykes, M.

    2008-01-01

    Using MIPS onboard the Spitzer Space Telescope, we observed the thermal emission (24 and, for some targets, 70 um) of eight irregular satellites of Saturn: Albiorix, Siarnaq, Paaliaq, Kiviuq, Ijiraq, Tarvos, Erriapus, and Ymir. We determined the size and albedo of all targets. An analysis of

  14. Forests, nitrogen and albedo, a very interesting trio indeed

    Directory of Open Access Journals (Sweden)

    Borghetti M

    2009-01-01

    Full Text Available A short comment is made on a recent paper (Ollinger et al. 2008 which shows that forest ecosystem carbon uptake in temperate and boreal forests is directly related to canopy nitrogen concentration and that both carbon uptake capacity and canopy nitrogen concentration are positively correlated with shortwave surface albedo measured with broad-band satellite sensors.

  15. Field measurement of albedo for limited extent test surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sailor, David J. [Portland State University, Department of Mechanical and Materials Engineering, P.O. Box 751-ME, Portland, OR 97207 (United States); Resh, Kyle; Segura, Del [Tulane University, Department of Mechanical Engineering, 400 Lindy Boggs Center, New Orleans, LA 70118 (United States)

    2006-05-15

    A new method is introduced for field measurement of surface albedo. This method consists of the use of a cylindrical shade ring made of opaque fabric with a known (low) albedo placed over a test surface. The albedo measurement is accomplished using two small pyranometers situated so that the downward-facing pyranometer receives radiation only from the test surface and the shade ring. The upward-facing pyranometer simultaneously records the incoming solar radiation. The radiation received by the downward-facing pyramometer is a combination of reflected radiation from shaded and unshaded portions of these two surfaces, requiring detailed accounting of the resulting view factor geometries. The method presented here improves upon past approaches by allowing for smaller sample sizes, minimizing errors associated with reflective properties of the surroundings, and allowing for accurate measurements even under partially cloudy skies. In addition to these methodological improvements we introduce an approach for estimating the uncertainty in the resulting albedo measurements. Results from field measurements are presented to validate the measurement protocol, and to compare its accuracy with the accuracy of a published standard. (author)

  16. Surface albedo following biochar application in durum wheat

    International Nuclear Information System (INIS)

    Genesio, L; Miglietta, F; Lugato, E; Baronti, S; Pieri, M; Vaccari, F P

    2012-01-01

    The agronomic use of charcoal from biomass pyrolysis (biochar) represents an interesting option for increasing soil fertility and sequestering atmospheric CO 2 . However, before moving toward large-scale biochar applications, additional research must evaluate all possible land–atmosphere feedbacks. Despite the increasing number of studies investigating the effect of biochar on soil physical, chemical and biological properties, only a few have been done on surface albedo variations on agricultural lands. The present work had the aim of characterizing the annual albedo cycle for a durum wheat crop in Central Italy, by means of a spectroradiometer measurement campaign. Plots treated with biochar, at a rate of 30–60 t ha −1 , showed a surface albedo decrease of up to 80% (after the application) with respect to the control in bare soil conditions, while this difference tended to decrease during the crop growing season, because of the prevailing effect of canopy development on the radiometer response. After the post-harvesting tillage, the soil treated with biochar again showed a lower surface albedo value (<20–26% than the control), while the measurements taken in the second year after application suggested a clear decrease of biochar influence on soil color. The modeling of the surface energy balance highlighted changes in the partitioning of heat fluxes and in particular a substantial increase of ground heat fluxes on an annual basis. (letter)

  17. Mimicking biochar-albedo feedback in complex Mediterranean agricultural landscapes

    International Nuclear Information System (INIS)

    Bozzi, E; Genesio, L; Miglietta, F; Toscano, P; Pieri, M

    2015-01-01

    Incorporation of charcoal produced by biomass pyrolysis (biochar) in agricultural soils is a potentially sustainable strategy for climate change mitigation. However, some side effects of large-scale biochar application need to be investigated. In particular a massive use of a low-reflecting material on large cropland areas may impact the climate via changes in surface albedo. Twelve years of MODIS-derived albedo data were analysed for three pairs of selected agricultural sites in central Italy. In each pair bright and dark coloured soil were identified, mimicking the effect of biochar application on the land surface albedo of complex agricultural landscapes. Over this period vegetation canopies never completely masked differences in background soil colour. This soil signal, expressed as an albedo difference, induced a local instantaneous radiative forcing of up to 4.7 W m −2 during periods of high solar irradiance. Biochar mitigation potential might therefore be reduced up to ∼30%. This study proves the importance of accounting for crop phenology and crop management when assessing biochar mitigation potential and provides more insights into the analysis of its environmental feedback. (letter)

  18. The effect of surface albedo and grain size distribution on ...

    African Journals Online (AJOL)

    Sand dams are very useful in arid and semi arid lands (ASALs) as facilities for water storage and conservation. Soils in ASALs are mainly sandy and major water loss is by evaporation and infiltration. This study investigated the effect of sand media characteristics, specifically surface albedo, grain size and stratification on ...

  19. Clear-Sky Narrowband Albedo Datasets Derived from Modis Data

    Science.gov (United States)

    Chen, Y.; Minnis, P.; Sun-Mack, S.; Arduini, R. F.; Hong, G.

    2013-12-01

    Satellite remote sensing of clouds requires an accurate estimate of the clear-sky radiances for a given scene to detect clouds and aerosols and to retrieve their microphysical properties. Knowing the spatial and angular variability of clear-sky albedo is essential for predicting the clear-sky radiance at solar wavelengths. The Clouds and the Earth's Radiant Energy System (CERES) Project uses the near-infrared (NIR; 1.24, 1.6 or 2.13 μm) and visible (VIS; 0.63 μm) channels available on the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS) to help identify clouds and retrieve their properties. Generally, clear-sky albedo for a given surface type is determined for conditions when the vegetation is either thriving or dormant and free of snow. The clear-sky albedos are derived using a radiative transfer parameterization of the impact of the atmosphere, including aerosols, on the observed reflectances. This paper presents the method of generating monthly clear-sky overhead albedo maps for both snow-free and snow-covered surfaces of these channels using one year of MODIS (Moderate Resolution Imaging Spectroradiometer) CERES products. Maps of 1.24 and 1.6 μm are being used as the background to help retrieve cloud properties (e.g., effective particle size, optical depth) in CERES cloud retrievals in both snow-free and snow-covered conditions.

  20. Effective single scattering albedo estimation using regional climate model

    CSIR Research Space (South Africa)

    Tesfaye, M

    2011-09-01

    Full Text Available In this study, by modifying the optical parameterization of Regional Climate model (RegCM), the authors have computed and compared the Effective Single-Scattering Albedo (ESSA) which is a representative of VIS spectral region. The arid, semi...

  1. Multidecadal analysis of forest growth and albedo in boreal Finland

    Czech Academy of Sciences Publication Activity Database

    Lukeš, Petr; Stenberg, P.; Mottus, M.; Manninen, T.; Rautiainen, M.

    2016-01-01

    Roč. 52, OCT (2016), s. 296-305 ISSN 0303-2434 R&D Projects: GA MŠk(CZ) LM2010007; GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : Albedo * fAPAR * LAI * NDVI * Time series * Seasonal trends * Forest structure Subject RIV: EH - Ecology, Behaviour Impact factor: 3.930, year: 2016

  2. Albedo and color maps of the Saturnian satellites

    International Nuclear Information System (INIS)

    Buratti, B.J.; Mosher, J.A.; Johnson, T.V.

    1990-01-01

    The paper discusses the production of maps of the albedos and colors of Mimas, Enceladus, Tethys, Dione, and Rhea over the full range of their imaged surfaces. Voyager images were used to prepare maps of the normal reflectances and color ratios (0.58/0.41 micron) of these satelites. 67 refs

  3. Spacecraft Attitude Determination with Earth Albedo Corrected Sun Sensor Measurements

    DEFF Research Database (Denmark)

    Bhanderi, Dan

    -Method, Extended Kalman Filter, and Unscented Kalman Filter algorithms are presented and the results are compared. Combining the Unscented Kalman Filter with Earth albedo and enhanced Sun sensor modeling allows for three-axis attitude determination from Sun sensor only, which previously has been perceived...

  4. Using BRDFs for accurate albedo calculations and adjacency effect corrections

    Energy Technology Data Exchange (ETDEWEB)

    Borel, C.C.; Gerstl, S.A.W.

    1996-09-01

    In this paper the authors discuss two uses of BRDFs in remote sensing: (1) in determining the clear sky top of the atmosphere (TOA) albedo, (2) in quantifying the effect of the BRDF on the adjacency point-spread function and on atmospheric corrections. The TOA spectral albedo is an important parameter retrieved by the Multi-angle Imaging Spectro-Radiometer (MISR). Its accuracy depends mainly on how well one can model the surface BRDF for many different situations. The authors present results from an algorithm which matches several semi-empirical functions to the nine MISR measured BRFs that are then numerically integrated to yield the clear sky TOA spectral albedo in four spectral channels. They show that absolute accuracies in the albedo of better than 1% are possible for the visible and better than 2% in the near infrared channels. Using a simplified extensive radiosity model, the authors show that the shape of the adjacency point-spread function (PSF) depends on the underlying surface BRDFs. The adjacency point-spread function at a given offset (x,y) from the center pixel is given by the integral of transmission-weighted products of BRDF and scattering phase function along the line of sight.

  5. The embeddedness of selfish Routines

    DEFF Research Database (Denmark)

    Andersen, Poul Houman

    2001-01-01

    Routines have traditionally been seen as an organisational feature. However, like genes, routines may be carriers and initiators of organisations as well......Routines have traditionally been seen as an organisational feature. However, like genes, routines may be carriers and initiators of organisations as well...

  6. The influence of inter-annually varying albedo on regional climate and drought

    KAUST Repository

    Meng, Xianhong; Evans, Jason P.; McCabe, Matthew

    2013-01-01

    Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done

  7. NLCD - MODIS land cover- albedo dataset for the continental United States

    Data.gov (United States)

    U.S. Environmental Protection Agency — The NLCD-MODIS land cover-albedo database integrates high-quality MODIS albedo observations with areas of homogeneous land cover from NLCD. The spatial resolution...

  8. An automated thermoluminescence dosimetry (TLD) system

    International Nuclear Information System (INIS)

    Kicken, P.J.H.; Huyskens, C.J.

    1979-01-01

    In the Health Physics Division of the Eindhoven University of Technology work is going on in developing an automated TLD-system. Process automization, statistical computation, dose calculation as well as dose recording are carried out, using a microcomputer and floppy disk unit. The main features of this TLD-system are its low costs, flexibility, easy to operate, and the feasibility for use in routine dosimetry as well as in complex TLD research. Because of its modular set-up several components of the system are multifunctional in other operations. The system seems suited for medium sized Health Physics groups. (Auth.)

  9. Albedo of a hybrid poplar plantation in central Alberta, Canada

    Science.gov (United States)

    Price, D. T.; Bernier, P. Y.; Orchansky, A.; Thomas, B.

    2012-04-01

    Canada's boreal forest resources are coming under increasing pressure from competing land-uses, including establishment of protected areas, and losses of harvestable forest to mining and oil and gas exploration. In the prairie region, concerns about lack of wood supply for pulpmills and potential opportunities for bioenergy production and carbon sequestration for climate change mitigation, have spurred interest in afforestation of marginal agricultural land, notably with fast-growing hybrid poplars (HP). However, global modelling studies suggest that a shift from grassland or crops to forest cover in temperate and boreal regions could result in reduced surface albedo, particularly in winter, causing an increase in radiative forcing and reducing any climate mitigation benefits due to net GHG removal. We report on seven growing seasons of measurements of short-wave canopy albedo using tower-mounted instruments, along with eddy covariance measurements of carbon, water and energy balance, at a site in central Alberta planted with HP cuttings in spring 2005. The data show little systematic change in average albedo as vegetation has changed from bare ground to a plantation of 6 m trees. Reasons for this include very wide (3 m) spacing between the trees, and snow cover which often persists for 4-5 months and is highly visible below the bare canopies during winter. While measurements should continue as the trees grow larger, we postulate that extensive afforestation with HP is unlikely to have major effects on regional-scale surface albedo compared to the agricultural systems they replace. Normal rotation lengths are 15-20 years, hence even if older plantations have significantly lower winter albedo, their contribution to the regional average would be relatively small because they will cover only a small fraction of the landscape (e.g., compared to forests of boreal conifers or temperate broadleaved species).

  10. Continuous versus discontinuous albedo representations in a simple diffusive climate model

    Science.gov (United States)

    Simmons, P. A.; Griffel, D. H.

    1988-07-01

    A one-dimensional annually and zonally averaged energy-balance model, with diffusive meridional heat transport and including icealbedo feedback, is considered. This type of model is found to be very sensitive to the form of albedo used. The solutions for a discontinuous step-function albedo are compared to those for a more realistic smoothly varying albedo. The smooth albedo gives a closer fit to present conditions, but the discontinuous form gives a better representation of climates in earlier epochs.

  11. Thermoluminescence dating. Application to the chronology of volcanic ashes

    International Nuclear Information System (INIS)

    Pilleyre, T.

    1991-09-01

    Thermoluminescent (TL) dating is generally used for minerals heated in the past and can be used for absolute chronology of volcanic ashes but seems limited to less than 15.000 years. The aim of the thesis is the study of thermoluminescent properties of quartz for high doses and long irradiations using the red TL peak of quartz which is situated at high temperature (about 370 deg. C) to extend the method for higher ages. A theory, based on spatial correlation between electron and hole created during the same ionization, is developed. A chapter is devoted to dosimetry because of its importance in TL dating, especially alpha scintillation counting and the influence of humidity on the determination of annual dose. Volcanic samples are dated from 10.000 to 80.000 years before present

  12. Study on carbonated hydroxyapatite as a thermoluminescence dosimeter

    International Nuclear Information System (INIS)

    Shafaei, M.; Sardari, D.; Ziaie, F.; Larijani, M.M.

    2015-01-01

    In this study, carbonated hydroxyapatite nanoparticles were used for thermoluminescence dosimetry. The nano-structure carbonated hydroxyapatite synthesized via hydrolysis of CaHPO 4 and CaCO 3 . The obtained nano powders were characterized by XRD technique and FTIR spectroscopy system. The carbonated hydroxyapatite samples were irradiated at different doses using 60 Co gamma rays, and were subjected to thermoluminescence measurement system, consequently. The TL glow curve exhibited two distinguishable peaks centered at around of 165 C and 310 C. The TL response of carbonated hydroxyapatite samples as a function of absorbed dose was linear in the range of 25-1000 Gy. Other dosimetric features of the carbonated hydroxyapatite nanoparticles including fading and reproducibility were also investigated.

  13. Thermoluminescence authentication of T'ang and Han Dynasty pottery

    International Nuclear Information System (INIS)

    Price, D.M.

    1997-01-01

    More than 80 pieces of T'ang Dynasty and 40 Han Dynasty style ceramic wares have been analysed to determine the amount of thermoluminescence (TL) accumulated since the initial firing of the object and the level of the radiation flux which has created the TL. This paper presents a summary of the thermoluminescence analysis results. Approximately 60% of Han ceramics and 45% of the T'ang pottery authenticated have been shown to belong to periods other than that stylistically suggested. Items which have been found not to be of the anticipated antiquity generally fall into distinct age groups. Of the T'ang wares the most commonly copied item is found to be the horse and for the Han pieces, human figures and ewers/pots/vases represent the most frequently reproduced wares

  14. Statistical methods to evaluate thermoluminescence ionizing radiation dosimetry data

    International Nuclear Information System (INIS)

    Segre, Nadia; Matoso, Erika; Fagundes, Rosane Correa

    2011-01-01

    Ionizing radiation levels, evaluated through the exposure of CaF 2 :Dy thermoluminescence dosimeters (TLD- 200), have been monitored at Centro Experimental Aramar (CEA), located at Ipero in Sao Paulo state, Brazil, since 1991 resulting in a large amount of measurements until 2009 (more than 2,000). The data amount associated with measurements dispersion, since every process has deviation, reinforces the utilization of statistical tools to evaluate the results, procedure also imposed by the Brazilian Standard CNEN-NN-3.01/PR- 3.01-008 which regulates the radiometric environmental monitoring. Thermoluminescence ionizing radiation dosimetry data are statistically compared in order to evaluate potential CEA's activities environmental impact. The statistical tools discussed in this work are box plots, control charts and analysis of variance. (author)

  15. Thermoluminescent dosemeter in a X-ray diffractometer

    International Nuclear Information System (INIS)

    Mendoza A, D.; Gonzalez M, P.; Falcon B, T.; Castano, V.M.

    1999-01-01

    In this work it was presented the results obtained of the dosimetry which was realized in a X-ray diffractometer for powders, trademark Siemens D5000, using the thermoluminescent signal generated by the X-rays in the commercial dosemeter TLD-100 of Harshaw, US. In according to the results obtained, the radiation quantity received by an analysed material in the diffractometer, will be proportional to exposure time and it can vary from unities until tenths of grays. These results are very outstanding when are analysed crystalline materials in a diffractometer, for knowing the present crystalline phases, mainly if these are highly sensitive to the ionizing radiation, as it is the case of the thermoluminescent materials. (Author)

  16. Comparative study of thermoluminescence detection methods for irradiated spices

    International Nuclear Information System (INIS)

    Kawamura, Y.; Kojima, K.; Sugita, T.; Yamada, T.; Saito, Y.

    1995-01-01

    The thermoluminescence (TL) detection methods for irradiated spices were compared using spice samples obtained on the Japanese market, irradiated at doses of 1, 5, 10 and 30 kGy and stored for 1 year before analysis. The TL intensities of irradiated spices were stable for 1 year after irradiation. Measurement with whole samples failed to identify irradiated samples. Minerals were separated from spices in sodium tungstate saturated solution and/or sodium polytungstate solution. The TL intensity of minerals which had undergone irradiation was significantly increased for all samples. However, the ranges of TL intensity of irradiated and unirradiated samples overlapped. Clear discrimination has been obtained between the TL ratios of irradiated and unirradiated spices by using normalized measurement with reirradiation. The detection limit in terms of irradiation dose is 1 kGy even in a sample that has been irradiated 1 year prior to analysis. Normalization is the best technique currently available for thermoluminescence analysis to identify irradiated spices

  17. Combination of archaeomagnetism and thermoluminescence for precision dating

    Science.gov (United States)

    Becker, H.; Göksu, H. Y.; Regulla, D. F.

    Archaeomagnetic dating was applied to two chalk-burning ovens from an early medieval noble-cemetery. Usually this method allows dating by the investigation of the geomagnetic declination and inclination through the thermoremanent magnetisation of baked clay in situ. However, in this case the method resulted in multiple dates since it was not possible to distinguish the brainching of the geomagnetic secular variation curve. Thermoluminescence dating was applied to the same samples to overcome the problem of multiple dates. This first combined application of archaeomagnetism and thermoluminescence for dating yielded A.D. 670±30 for the two ovens, which dates the first stone-church at the site after a wooden predecessor archeologically dated A.D. 620-630.

  18. Observations on some thermoluminescence emission centres in geological quartz

    International Nuclear Information System (INIS)

    Scholefield, R.B.; Prescott, J.R.; Fox, P.J.; Franklin, A.D.

    1994-01-01

    We report measurements of three-dimensional thermoluminescence emission spectra of samples of geological quartz, derived from Australian sediments. The emphasis is on peaks of particular practical interest for thermoluminescence sediment dating, viz. the 110 o C peak, which is used for pre-dose dating and the peak at 325 o C, which is of significance for partial and selective bleach techniques and for optically stimulated luminescence (OSL) dating. Because the 325 o C peak can be bleached to essentially zero, it can be isolated in a given spectrum by subtracting the bleached spectrum from the unbleached spectrum. By including both peaks in the same spectrum, it is demonstrated that they do not emit at the same wavelength, although this does not necessarily mean that the emission is from different emission centres. The 375 o C peak, which is important in total bleach methods, emits at a distinguishable wavelength. The use of bleaching and subtraction in practical dating is discussed. (Author)

  19. Preliminary research on thermoluminescence application in complicated geological situation

    International Nuclear Information System (INIS)

    Gong Gelian; Liu Chunsheng

    2003-01-01

    Thermoluminescent phenomenon resulting from two kinds of complicated geological situation, Ordos Basin and Huainan deposits in Anhui Province, is studied by the means of thermoluminescence counting method. It is shown that: (1) there are no apparent abnormalities of natural TL detected from the rock samples selected in the first 1000 meter depth of the Earth, and these natural TL are accumulated through natural radiation effects; (2) the natural TL shows statistically obvious reducing trends for the rock samples selected under the 2000 meter depth, and even no detectable TL is found for those rocks selected at 4000 meter depth. (3) the natural TL peaks corresponding to high temperature generally shift to the direction of higher temperature for the quartz-related rock samples, and several thermal events which occurred during the geological times might be responsible for this case

  20. Thermoluminescence of sulfated zircon exposed to gamma radiation

    International Nuclear Information System (INIS)

    Rubio, E.; Castano, V.M.; Mendoza A, E.; Gonzalez, P.R.

    2003-01-01

    In this work, the thermoluminescent (Tl) signal induced by gamma radiation in zirconia and sulfated zirconia samples embedded in Ptfe pellets is reported and discussed. In this case, samples were obtained through sol-gel method using zirconium n-propoxide and H 2 SO 4 as precursors, and later were subjected to thermal treatment at 600 C to obtain, the tetragonal phase accordingly to X-ray diffraction analysis. Experimental results show that the thermoluminescent glow peak depends on both, the crystalline structure and sulfate concentration. Two maximum peaks were observed located at 147 C and 274 C arising from the electronic transitions. Tl response as a function of the absorbed dose shows a linear increase for a wide of range exposure as well as good stability in time. The high sensitivity, dose linearity and signal stability of this material open the potential possibility to be used for the dosimetry applications. (Author)

  1. Suitability of the thermoluminescence method for detection of irradiated foods

    International Nuclear Information System (INIS)

    Pinnioja, S.

    1993-01-01

    Irradiated foods can be detected by thermoluminescence (TL) of contaminating minerals. Altogether about 300 lots of herbs, spices, berries, mushrooms and seafood were studied by the TL method. Irradiated herbs and spices were easily differentiated from unirradiated ones two years after irradiation of a 10 kGy dose. The mineral composition of seafood was variable; and while calcite was suitable for the TL analysis, aragonite and smectite gave unreliable results. Control analyses during two years confirmed the reliability of TL method. (author)

  2. Dosimetry of accidents using thermoluminescence of dental restorative porcelains

    International Nuclear Information System (INIS)

    Mauricio, C.L.P.; Rosa, L.A.R. da; Cunha, P.G. da

    1986-01-01

    The thermoluminescence (TL) properties of dental restorative porcelain were investigated with the aim of using this material as a TL dosemeter to estimate high doses in radiological accidents. The irradiations were carried out with a 60 Co gamma source and X rays with effective energies from 29 to 95 KeV. The samples have a limit of detection at about 50R and their reproducibility is better than 15%. Linearity was observed from 50 to 5000R. (Author) [pt

  3. Confrontation of thermoluminescence models in lithium fluoride with experimental data

    International Nuclear Information System (INIS)

    Niewiadomski, T.

    1976-12-01

    The thermoluminescent properties of lithium fluoride depend on numerous factors and are much more complex than those of other phosphors. The so far developed fragmentary models are meant to explain the relationships between crystal defect structure and the processes involved in TL. An attempt has been made to compare these models with the veryfied experimental data and to point out the observations which are inconsistant with the models. (author)

  4. Preparation of lithium fluoride for thermoluminescent detectors of ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Mironenko, S.N.; Nepomnyashchikh, A.I.; Ikrami, D.D.; Paramzin, A.S.; Rakhimov, M.Eh.

    1985-03-01

    The thermostimulated luminescence (TSL) of lithium fluoride monocrystals depending on the method of preparation of starting raw material and features of its preliminary processing is investigated. It is shown that only lithium fluoride of high purity prepared through the stage of formation of hydrofluoride and its subsequent decomposition can be used without any additional processing for manufacturing monocrystal detectors of thermoluminescent dosimetry of the ionizing radiation with low intensity of low temperature peaks.

  5. Substance for thermoluminescent dosimetry of photon radiation in adipose tissue

    International Nuclear Information System (INIS)

    Kalmykov, L.Z.; Kandel', T.G.

    1983-01-01

    Substance composition for thermoluminescent photon dosimetry in adipose tissue is proposed which makes it possible to simplify dosimetric measurements and to improve their accuracy. The substance consists of powder-like thermoluminophor Li 2 B 4 O 7 (0.03%Mn) 48-52 mass % and bistriethylammonium dodecahydrododecaborane - 48-52 mass %. The above substance is equivalent in respect to dosimetry to adipose tissue within the 10 keV - 10 MeV energy range

  6. A thermoluminescence study of vempalle dolomites and its depositional environments

    International Nuclear Information System (INIS)

    Bhattacharya, A.K.; Rao, C.N.; Kaul, I.K.

    1976-01-01

    An attempt has been made to interpret the depositional environment of Vempalle dolomites (India) by thermoluminescence method. It has been demonstrated that glow curve patterns reflect the environmental condition of deposition for carbonate sediments. The glow curves were obtained for natural samples as well as samples irradiated by Co 60 and compared. A majority of the samples were concluded to be diagenetic. (A.K.)

  7. Thermoluminescence sensitivity variations in LiF PTFE dosemeters incurred by improper handling procedures

    CERN Document Server

    Mason, E W; MacKinlay, Alistair F; Saunders, D

    1975-01-01

    A systematic study of some anomalous darkening effects and thermoluminescence sensitivity variations observed in LiF:PTFE thermoluminescent dosemeters is described. Various likely causes of such effects have been investigated. The manufacturer's recommended cleaning procedures have been found to be inadequate and, in some cases, have been found to actually promote discolouration of the dosemeters. Recommendations are given for the successful use of LiF:PTFE thermoluminescent dosemeters in personal dosimetry.

  8. Thermoluminescence of LiF: Mg, Ti between 77 and 315 K

    International Nuclear Information System (INIS)

    Rosa, L.A.R. da.

    1989-01-01

    A special thermoluminescent system was developed. It is able to operate right from liquid nitrogen temperature and also permits the determination of the sample thermoluminescent emission spectrum. Using this system, the thermoluminescence displayed by 77 K irradiated LiF:Mg,Ti (TLD-100), from the irradiation temperature to 315 K, was studied. In this temperature range seven glow peaks, at 139, 153, 194, 240, 260, 283 and 300 K, were determined. (author)

  9. Food irradiation dosimetry using thermoluminescence of quartz sand

    International Nuclear Information System (INIS)

    Khan, H.M.; Ehlermann, D.A.E.

    1993-01-01

    Thermoluminescence of quartz sand, which is inert and concomitant to several food materials, has been investigated for applications in food irradiation dosimetry and detection of irradiated foods. The glow curves consist of at least three overlapping peaks from 100 to 420 C. The peak at lower temperature is not stable and decays quickly at room temperature. However, the peaks at higher temperature are stable and more useful for dosimetry work. The intensity of the peak at 360 C, measured using different optical filters, shows a linear response in the range of 0.05 to 23 kGy. Stability of these signals at different annealing temperatures has been investigated. Thermoluminescence from adhering minerals and contaminating dust in different food materials has been found useful for the detection of irradiation treatment. Since quartz is frequently one of these minerals, further computerized deconvolution of individual glow peaks from the complex glow curves of quartz sand was carried out which improves the dosimetric results. Possible applications of thermoluminescence of quartz sand in food irradiation dosimetry and detection of irradiated foods have been discussed. (orig.)

  10. Thermoluminescence kinetics of pyrite (FeS2)

    International Nuclear Information System (INIS)

    Silverman, A.N; Levy, P.W.; Kierstead, J.A.

    1990-01-01

    Thermoluminescence of pyrite (FeS 2 ) has been investigated to study the kinetics of single peak glow curves. The material used normally exhibits one large and four small peaks. However a glow curve can be obtained with only the large single peak that is suitable for testing thermoluminescence kinetics. Glow curves from aliquots of a single natural pyrite crystal studied in detail contain two low intensity thermoluminescence (TL) peaks at ∼90 degree and ∼250 degree C, and two chemiluminescence (CL) peaks at ∼350 degree and ∼430 degree C. The CL peaks are largely removable by initially heating the sample chamber under vacuum, pumping through liquid nitrogen traps, and recording glow curves immediately after helium is introduced, procedures which reduce system contaminants that react with pyrite. The shape, the variation of the temperature of the peak maximum (T max ) with dose, and the retrapping to recombination cross section ratio σ of the large 250 degree C peak are better described by the general one trap (GOT) kinetic equation, the basic equation from which the 1st and 2nd order kinetic equations are obtained as special cases (see text), than by the 1st and 2nd order equations. 12 refs., 7 figs

  11. Comparison of responses of thermoluminescent dosemeters irradiated by soft x-rays at very low and very high dose rate levels

    International Nuclear Information System (INIS)

    Pietrikova-Farnikova, M.; Krasa, J.; Juha, L.

    1994-01-01

    Recent great progress in construction and application of bright sources of soft X-rays gave a strong impetus for the development of methods of their dosimetric diagnostics. The soft X-ray sources are primarily represented by synchrotron radiation sources and by sources based on laser-produced plasma, including X-ray lasers. Their characteristics spread over a very wide region of photon energies, peak and average powers and densities. From our preliminary experiments it follows that thermoluminescent dosemeters can serve as a suitable tool for the determination of these characteristics. Problem lies in the fact that routine use of the thermoluminescent dosemeters for the dosimetry of soft X-rays requires their spectral calibration, which can be carried out with low peak power sources (synchrotron radiation and radionuclide sources). On the contrary, many important sources, especially these based on laser-produced plasmas, exhibit a very high peak power, i.e. dosemeters are irradiated at extremely high dose rate. In comparative experiments carried out with laser-produced plasmas and radionuclides using TLD 200 (CaF 2 :Dy) and GR 200A (LiF:Mg,Cu,P) it was satisfactorily proven that total thermoluminescent signals are independent of the dose rate. Dependence of glow curve shapes on the dose, dose rate and photon energy were equally determined

  12. Simultaneous improvement in productivity, water use, and albedo through crop structural modification.

    Science.gov (United States)

    Drewry, Darren T; Kumar, Praveen; Long, Stephen P

    2014-06-01

    Spanning 15% of the global ice-free terrestrial surface, agricultural lands provide an immense and near-term opportunity to address climate change, food, and water security challenges. Through the computationally informed breeding of canopy structural traits away from those of modern cultivars, we show that solutions exist that increase productivity and water use efficiency, while increasing land-surface reflectivity to offset greenhouse gas warming. Plants have evolved to maximize capture of radiation in the upper leaves, thus shading competitors. While important for survival in the wild, this is suboptimal in monoculture crop fields for maximizing productivity and other biogeophysical services. Crop progenitors evolved over the last 25 million years in an atmosphere with less than half the [CO2] projected for 2050. By altering leaf photosynthetic rates, rising [CO2] and temperature may also alter the optimal canopy form. Here using soybean, the world's most important protein crop, as an example we show by applying optimization routines to a micrometeorological leaf canopy model linked to a steady-state model of photosynthesis, that significant gains in production, water use, and reflectivity are possible with no additional demand on resources. By modifying total canopy leaf area, its vertical profile and angular distribution, and shortwave radiation reflectivity, all traits available in most major crop germplasm collections, increases in productivity (7%) are possible with no change in water use or albedo. Alternatively, improvements in water use (13%) or albedo (34%) can likewise be made with no loss of productivity, under Corn Belt climate conditions. © 2014 California Institute of Technology. Government sponsorship acknowledged.

  13. Variation in thermoluminescence of irradiated brands of foodstuffs: a test for hygienic quality

    International Nuclear Information System (INIS)

    Mamoon, A.; Zaheer, A.; Abu-Abdullah, S.

    1996-01-01

    Thermoluminescence of irradiated foodstuffs such as herbs and spices, is mostly due to attached dust or soil particles. Different brands of the same foodstuff sometimes give thermoluminescent signals of different intensities, apparently due to different degrees of dust contamination. It is of obvious importance to choose brands of foodstuffs that appear to have less dust contamination, i.e. of better hygienic quality. Several food items were investigated with respect to their thermoluminescent (TL) emission in order to assess TL usefulness as an indicator of hygienic quality for foods prone to contamination by dust. In this regard some foodstuff were artificially contaminated with a soil sample and their thermoluminescent emission was obtained. (author)

  14. A study of the high-temperature signal characteristics in the thermoluminescence of porcelain

    International Nuclear Information System (INIS)

    Yin Gongming

    2001-01-01

    The thermoluminescence pre-dose technique for dating ancient porcelain was developed in many laboratories. This technique was the only method which could directly determine the age of old porcelain. But the thermoluminescence high-temperature signal (over 200 degree C) had not been studied. The authors conduced a preliminary study of the characteristic of thermoluminescence high-temperature signal, such as the TL natural glow curve, and the glow curves after beta or alpha irradiation. Most of the 32 ancient porcelains had thermoluminescence high temperature signal, and only one peak in their TL glow curve was found

  15. Long-term record of top-of-atmosphere albedo generated from AVHRR data

    Science.gov (United States)

    Song, Z.

    2017-12-01

    Top-of-Atmosphere (TOA) albedo is a fundamental component of Earth's energy budget. Previously, long-term accurate TOA albedo products did not exist due to the lack of stable broadband observations. With a new albedo estimation methodology based on multispectral observations, TOA albedo since 1981 has been retrieved using data from the Advanced Very High Resolution Radiometer (AVHRR), which provides the longest record of satellite observations across the globe. To develop the long-term TOA albedo record, the instantaneous TOA albedo was calculated by the direct estimation method, which was built on training data pairs from coincident AVHRR TOA reflectance and Moderate Resolution Imaging Spectroradiometer (MODIS) TOA albedo. The instantaneous TOA albedo was then converted to daily mean and monthly mean albedo based on the diurnal curves from geostationary satellites. The TOA albedo results (AVHRR-TAL) were compared with Clouds and the Earth's Radiant Energy System (CERES) flux products for 2007. The monthly mean AVHRR-TAL agreed well with the CERES products, with a root mean square difference (RMSD) of 0.032 and a bias of 0.013. In addition, AVHRR-TAL showed similar seasonal variations to those seen in the CERES products. Further analysis on long-term time series showed good consistency between the two datasets (R2 > 0.95 and relative RMSD < 4%) from 2000 to 2015. Although some calibration issues remain to be solved, our datasets show the potential ability to observe the global TOA albedo from 1981 to the present.

  16. Measuring the influence of aerosols and albedo on sky polarization.

    Science.gov (United States)

    Kreuter, A; Emde, C; Blumthaler, M

    2010-11-01

    All-sky distributions of the polarized radiance are measured using an automated fish-eye camera system with a rotating polarizer. For a large range of aerosol and surface albedo situations, the influence on the degree of polarization and sky radiance is investigated. The range of aerosol optical depth and albedo is 0.05-0.5 and 0.1-0.75, respectively. For this range of parameters, a reduction of the degree of polarization from about 0.7 to 0.4 was observed. The analysis is done for 90° scattering angle in the principal plane under clear sky conditions for a broadband channel of 450 ± 25 nm and solar zenith angles between 55° and 60°. Radiative transfer calculations considering three different aerosol mixtures are performed and and agree with the measurements within the statistical error.

  17. Cosmic ray induced charged particle albedos in the upper atmosphere

    International Nuclear Information System (INIS)

    Bhatnagar, S.P.; Verma, S.D.

    1982-01-01

    There are several observations made in balloon and satellite experiments of relativistic albedo electrons in 50 to 10,000 MeV energy region. The spectrum of these electrons is a power law with negative exponent. At lower energies, 1 to 50 MeV region theoretical evaluations indicate that their energy spectrum will have a similar shape, thus the flux at low energies will be much higher. The only spectrum measurements available below 20 MeV were taken at Ft. Churchill by Hovestadt and Meyer (1969). The flux and energy spectrum of the Re-entrant albedos electrons have been calculated in the energy range 3-50 MeV for Ft. Churchill, Canada, Palestein, Texas and Hyderabad, India, and are presented. The angular distribution of re-entrant electrons in the upper atmosphere is not yet observed, however Kurnosova et. al. (1979) have measured the Vertical and Horizontal integral flux at Hyderabad, India

  18. Albedo decreasing trend. White cars proposal and new urban scenarios

    Directory of Open Access Journals (Sweden)

    Niccolò Casiddu

    2014-05-01

    Full Text Available Global warming caused the decrease of the albedo. Emission reduction is the most widely proposed response to this problem. However simple ideas such as cool roofs and cool pavements seem successful remedies to counter the threat. However in Italy another strategy appears more effective. By changing from dark to pastel bright automotive colours a considerable increase of the albedo can be hypothesized: the effect should be from 32% to 50% of the results obtained with an extensive application of the “cool roofs” strategy. Such a proposal involves the creation of new, unexpected cityscapes. The city is a place where the perception of space changes. The car, by definition is an object in motion, but still present, sometimes redundant in the urban landscape. What will be the perceived relationship with buildings, streets, squares where the cars are all white or pastel colour?

  19. Calculating the albedo characteristics by the method of transmission probabilities

    International Nuclear Information System (INIS)

    Lukhvich, A.A.; Rakhno, I.L.; Rubin, I.E.

    1983-01-01

    The possibility to use the method of transmission probabilities for calculating the albedo characteristics of homogeneous and heterogeneous zones is studied. The transmission probabilities method is a numerical method for solving the transport equation in the integrated form. All calculations have been conducted as a one-group approximation for the planes and rods with different optical thicknesses and capture-to-scattering ratios. Above calculations for plane and cylindrical geometries have shown the possibility to use the numerical method of transmission probabilities for calculating the albedo characteristics of homogeneous and heterogeneous zones with high accuracy. In this case the computer time consumptions are minimum even with the cylindrical geometry, if the interpolation calculation of characteristics is used for the neutrons of the first path

  20. Colour, albedo and nucleus size of Halley's comet

    Science.gov (United States)

    Cruikshank, D. P.; Tholen, D. J.; Hartmann, W. K.

    1985-01-01

    Photometry of Halley's comet in the B, J, V, and K broadband filters during a time when the coma was very weak and presumed to contribute negligibly to the broadband photometry is reported. The V-J and J-K colors suggest that the color of the nucleus of Halley's comet is similar to that of the D-type asteroids, which in turn suggests that the surface of the nucleus has an albedo less than 0.1.

  1. PENGAMBILAN PEKTIN DARI ALBEDO SEMANGKA DENGAN PROSES EKSTRAKSI ASAM

    Directory of Open Access Journals (Sweden)

    Melisa Triandini Maulani

    2014-04-01

    Full Text Available Watermelon is a plant that is resistant to dry climate so it can be grown in tropical and semi-desert. Watermelon albedo is a potential source of pectin because it contains pectin compounds. To decompose the pectin in the watermelon albedo can be done by acid extraction process because it will lesser the possibility of damage pectin, whereas alcohol is use to precipitate pectin. In this research watermelon albedo as basic ingredients would be extracted to produce pectin to identified the differences in the influence of temperature variation and the type of solvent extraction of the pectin content of the albedo watermelon and determined variations in maximum temperature and type of solvent extraction to produce pectin. The study was conducted with a 90-minute extraction time and extraction temperature 60, 70, and 80 °C and 500 mL the solvent HCl and CH3COOH with 2.6 pH. The results were obtained taking the maximum conditions of pectin using solvent extraction HCl at a temperature of 80 °C and obtained pectin levels of 11.2635%. Solvent which is a strong acid HCl is easier to untie protopektin pectin so pectin levels has generated a high level. The higher the operating temperature, the bigger pectin levels that are obtained until the temperature limit of 80 °C. This caused by the movement of the H+ ions more reactive, the more contact between the substances dissolved in the sample with solvent and obtained more pectin.

  2. Multidecadal Variability in Surface Albedo Feedback Across CMIP5 Models

    Science.gov (United States)

    Schneider, Adam; Flanner, Mark; Perket, Justin

    2018-02-01

    Previous studies quantify surface albedo feedback (SAF) in climate change, but few assess its variability on decadal time scales. Using the Coupled Model Intercomparison Project Version 5 (CMIP5) multimodel ensemble data set, we calculate time evolving SAF in multiple decades from surface albedo and temperature linear regressions. Results are meaningful when temperature change exceeds 0.5 K. Decadal-scale SAF is strongly correlated with century-scale SAF during the 21st century. Throughout the 21st century, multimodel ensemble mean SAF increases from 0.37 to 0.42 W m-2 K-1. These results suggest that models' mean decadal-scale SAFs are good estimates of their century-scale SAFs if there is at least 0.5 K temperature change. Persistent SAF into the late 21st century indicates ongoing capacity for Arctic albedo decline despite there being less sea ice. If the CMIP5 multimodel ensemble results are representative of the Earth, we cannot expect decreasing Arctic sea ice extent to suppress SAF in the 21st century.

  3. Detection of irradiated food: Thermoluminescence analysis of spices, herbs, and spice-and-herb products. Thermolumineszenz-Analyse an Gewuerzen, Kraeutern und Gewuerz- und Kraeutermischungen

    Energy Technology Data Exchange (ETDEWEB)

    Schreiber, G A [Fachgebiet Lebensmittelbestrahlung, Bundesgesundheitsamt, Berlin (Germany); Helle, N [Fachgebietsgruppe Lebensmittel- und Arzneimittelbestrahlung, Bundesgesundheitsamt, Berlin (Germany); Boegl, K W

    1993-09-01

    About 3 and 9 months after irradiation 14 laboratories determined the thermoluminescence (TL) of mineral contaminations which were isolated from different coded spice-and-herb products. In both study periods 99% of the 317 samples (total number) were correctly identified as irradiated or non-irradiated on the basis of normalized TL intensities. Only three irradiated samples were not identified as irradiated. The results show that irradiation of spices, herbs and spice-and-herb mixtures can be clearly detected throughout the entire period in which the products are normally stored, and that the method is suitable for routine analysis in food control laboratories. (orig.)

  4. Distinguishing the albedo of exoplanets from stellar activity

    Science.gov (United States)

    Serrano, L. M.; Barros, S. C. C.; Oshagh, M.; Santos, N. C.; Faria, J. P.; Demangeon, O.; Sousa, S. G.; Lendl, M.

    2018-03-01

    Context. Light curves show the flux variation from the target star and its orbiting planets as a function of time. In addition to the transit features created by the planets, the flux also includes the reflected light component of each planet, which depends on the planetary albedo. This signal is typically referred to as phase curve and could be easily identified if there were no additional noise. As well as instrumental noise, stellar activity, such as spots, can create a modulation in the data, which may be very difficult to distinguish from the planetary signal. Aims: We analyze the limitations imposed by the stellar activity on the detection of the planetary albedo, considering the limitations imposed by the predicted level of instrumental noise and the short duration of the obervations planned in the context of the CHEOPS mission. Methods: As initial condition, we have assumed that each star is characterized by just one orbiting planet. We built mock light curves that included a realistic stellar activity pattern, the reflected light component of the planet and an instrumental noise level, which we have chosen to be at the same level as predicted for CHEOPS. We then fit these light curves to try to recover the reflected light component, assuming the activity patterns can be modeled with a Gaussian process. Results: We estimate that at least one full stellar rotation is necessary to obtain a reliable detection of the planetary albedo. This result is independent of the level of noise, but it depends on the limitation of the Gaussian process to describe the stellar activity when the light curve time-span is shorter than the stellar rotation. As an additional result, we found that with a 6.5 magnitude star and the noise level of CHEOPS, it is possible to detect the planetary albedo up to a lower limit of Rp = 0.03 R*. Finally, in presence of typical CHEOPS gaps in the simulations, we confirm that it is still possible to obtain a reliable albedo.

  5. The New Global Gapless GLASS Albedo Product from 1981 to 2014

    Science.gov (United States)

    Dou, B.; Liu, Q.; Qu, Y.; Wang, L.; Feng, Y.; Nie, A.; Li, X.; Zhang, J.; Niu, H.; Cai, E.; Zhao, L.

    2016-12-01

    Long-time series and various spatial resolution albedo products are needed for climate change and environmental studies at both global and regional scale. To meet these requirements, GLASS (Global LAnd Surface Satellites) gapless albedo product from 1981 to 2010 was firstly released in 2012 and widely used in long-term earth change researches. However, only shortwave albedo product in spatial resolution of 0.05 degree and 1 km were provided, which limits extensive applications for visible and near-infrared bands. Thus, new GLASS albedo product are produced and comprehensively enhanced in time series, algorithm and product content. Five major updates are conducted: 1) Time region is expanded from 1981-2010 to 1981-2014; 2) Physically ART (radiative transfer theory) and TCOWA (Three-Component Ocean Water Albedo) models rather than previous RTLSR (Rose-Thick Li-Sparse Reciprocal kernel combination) model are adopted for snow and inland water albedo estimation, respectively; 3) global shortwave, visible, and near-infrared albedos in spatial resolution of 0.05 degree and 1 km are released; 4) Clear-sky albedo is provided beyond the traditional black-sky albedo and white sky-albedo for amateurish user; 5) 250 m albedo product is provided in part of global for regional application. In this study, we firstly detail the updates of this inspiring product. Then the product is compared with the previous GLASS albedo product and preliminary assessed against field measurements under various land covers. Significant improvements are reported for snow and water albedo. The results demonstrate that the new GLASS albedo product is a gapless, long-term continuous, and self-consistent data-set. Comparing to previous GLASS albedo product, lower black-sky albedo and higher white-sky albedo are proved for permanent snow-cover region. Moreover, higher albedo of inland water and seasonal snow-cover mountain are captured. This product brings new chance and view to understanding long

  6. A CR-39 track dosemeter for routine individual neutron monitoring

    International Nuclear Information System (INIS)

    Luszik-Bhadra, M.; Alberts, W.G.; Dietz, E.; Guldbakke, S.; Matzke, M.; d'Errico, F.

    1994-01-01

    A personal neutron dosemeter for routine individual monitoring is proposed. It is based on a CR-39 track detector covered on three separate areas by converters with different boron contents and inserted into a commercial TLD albedo dosemeter capsule. The dose readings from three areas of the electrochemically etched CR-39 detector are combined to yield a dose equivalent response which is almost independent of the incident neutron energy in the range from thermal neutrons up to 20 MeV. In addition, the dose contributions of thermal, intermediate and fast neutrons can be determined separately. Unlike the TLD albedo dosemeter, which in general requires prior in-field calibration and whose use is then restricted to that field, this dosemeter can be used in neutron fields without any knowledge of the spectral distribution with the same calibration factor. The angular dependence of the dosemeter's response has been measured and compared with that of the directional dose equivalent H'(10). The lower limit of detection is 0.15 mSv. It is possible to obtain an independent, second dose reading from the same Cr-39 detector for neutron energies above 100 keV. The dosemeter has also been successfully tested for use in accident dosimetry applying chemical etching and an optical density reading of the CR-39 detector. (author)

  7. Inclusion of Solar Elevation Angle in Land Surface Albedo Parameterization Over Bare Soil Surface.

    Science.gov (United States)

    Zheng, Zhiyuan; Wei, Zhigang; Wen, Zhiping; Dong, Wenjie; Li, Zhenchao; Wen, Xiaohang; Zhu, Xian; Ji, Dong; Chen, Chen; Yan, Dongdong

    2017-12-01

    Land surface albedo is a significant parameter for maintaining a balance in surface energy. It is also an important parameter of bare soil surface albedo for developing land surface process models that accurately reflect diurnal variation characteristics and the mechanism behind the solar spectral radiation albedo on bare soil surfaces and for understanding the relationships between climate factors and spectral radiation albedo. Using a data set of field observations, we conducted experiments to analyze the variation characteristics of land surface solar spectral radiation and the corresponding albedo over a typical Gobi bare soil underlying surface and to investigate the relationships between the land surface solar spectral radiation albedo, solar elevation angle, and soil moisture. Based on both solar elevation angle and soil moisture measurements simultaneously, we propose a new two-factor parameterization scheme for spectral radiation albedo over bare soil underlying surfaces. The results of numerical simulation experiments show that the new parameterization scheme can more accurately depict the diurnal variation characteristics of bare soil surface albedo than the previous schemes. Solar elevation angle is one of the most important factors for parameterizing bare soil surface albedo and must be considered in the parameterization scheme, especially in arid and semiarid areas with low soil moisture content. This study reveals the characteristics and mechanism of the diurnal variation of bare soil surface solar spectral radiation albedo and is helpful in developing land surface process models, weather models, and climate models.

  8. Sea Ice, Clouds, Sunlight, and Albedo: The Umbrella Versus the Blanket

    Science.gov (United States)

    Perovich, D. K.

    2017-12-01

    The Arctic sea ice cover has undergone a major decline in recent years, with reductions in ice extent, ice thickness, and ice age. Understanding the feedbacks and forcing driving these changes is critical in improving predictions. The surface radiation budget plays a central role in summer ice melt and is governed by clouds and surface albedo. Clouds act as an umbrella reducing the downwelling shortwave, but also serve as a blanket increasing the downwelling longwave, with the surface albedo also determining the net balance. Using field observations from the SHEBA program, pairs of clear and cloudy days were selected for each month from May through September and the net radiation flux was calculated for different surface conditions and albedos. To explore the impact of albedo we calculated a break even albedo, where the net radiation for cloudy skies is the same as clear skies. For albedos larger than the break-even value the net radiation flux is smaller under clear skies compared to cloudy skies. Break-even albedos ranged from 0.30 in September to 0.58 in July. For snow covered or bare ice, clear skies always resulted in less radiative heat input. In contrast, leads always had, and ponds usually had, more radiative heat input under clear skies than cloudy skies. Snow covered ice had a net radiation flux that was negative or near zero under clear skies resulting in radiative cooling. We combined the albedo of individual ice types with the area of those ice types to calculate albedos averaged over a 50 km x 50 km area. The July case had the smallest areally averaged albedo of 0.50. This was less than the breakeven albedo, so cloudy skies had a smaller net radiation flux than clear skies. For the cases from the other four months, the areally averaged albedo was greater than the break-even albedo. The areally averaged net radiation flux was negative under clear skies for the May and September cases.

  9. Numerical analysis of thermoluminescence glow curves; Analisis numerico de las cruvas de termoluminiscencia

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Ros, J M; Delgado, A

    1989-07-01

    This report presents a method for the numerical analysis of complex thermoluminescence glow curves resolving the individual glow peak components. The method employs first order kinetics analytical expressions and is based In a Marquart-Levenberg minimization procedure. A simplified version of this method for thermoluminescence dosimetry (TLD) is also described and specifically developed to operate whit Lithium Fluoride TLD-100. (Author). 36 refs.

  10. Thermoluminescence, a method for determining the date at which a ceramic object was fired

    International Nuclear Information System (INIS)

    Sayre, E.V.

    The theory on which thermoluminescence dating of archeological ceramic objects is based and the measurement methods used are outlined. Separation of fine grain particles and quartz particles permits the determination of the thermoluminescence of each and often a more accurate age determination. The application of the method to the dating of a bronze horse from the Metropolitan Museum is described

  11. Study of some thermoluminescent phosphors for the dosimetry of ionizing radiations

    International Nuclear Information System (INIS)

    Jaafari, M.

    1983-01-01

    Thermoluminescence dosimetry techniques are reviewed and interactions radiation matter are recalled. The need for new phosphors is evidenced. Numerous phosphors are examined and calcium, strontium and barium sulfides are synthetized and deposited on glass supports. The thermoluminescence of the dosimeters obtained with these materials is analyzed [fr

  12. Relationship between thermoluminescence and X-ray induced luminescence in alkali halides

    International Nuclear Information System (INIS)

    Aguilar, M.; Lopez, F.J.; Jaque, F.

    1978-01-01

    The wavelength spectra of thermoluminescence and X-ray induced luminescence in pure and divalent cation doped alkali halides, in the temperature range LNT-RT have been studied. The more important conclusion is that the wavelength spectra in both cases are very similar. This allows a new point of view to be presented on thermoluminescence mechanisms. (author)

  13. Thermoluminescent response of LiF before variation of the heating rate

    International Nuclear Information System (INIS)

    Barrios, R.; Avila, O.

    2003-01-01

    Comparisons of glow curves of lithium fluoride dosemeters TLD-100 measured to two heating rates with the purpose of quantifying the change in the temperature of the peaks 5 and 7 for the thermoluminescent reader equipment Harshaw 4000 of the thermoluminescence laboratory of the ININ were carried out. (Author)

  14. Depth dose curves from 90Sr+90Y clinical applicators using the thermoluminescent technique

    International Nuclear Information System (INIS)

    Antonio, Patricia L.; Caldas, Linda V.E.; Oliveira, Mercia L.

    2009-01-01

    The 90 Sr+ 90 Y beta-ray sources widely used in brachytherapy applications were developed in the 1950's. Many of these sources, called clinical applicators, are still routinely used in several Brazilian radiotherapy clinics for the treatment of superficial lesions in the skin and eyes, although they are not commercialized anymore. These applicators have to be periodically calibrated, according to international recommendations, because these sources have to be very well specified in order to reach the traceability of calibration standards. In the case of beta-ray sources, the recommended quantity is the absorbed dose rate in water at a reference distance from the source. Moreover, there are other important quantities, as the depth dose curves and the source uniformity for beta-ray plaque sources. In this work, depth dose curves were obtained and studied of five dermatological applicators, using thin thermoluminescent dosimeters of CaSO 4 :Dy and phantoms of PMMA with different thicknesses (between 1.0 mm and 5.0 mm) positioned between each applicator and the TL pellets. The depth dose curves obtained presented the expected attenuation response in PMMA, and the results were compared with data obtained for a 90 Sr+ 90 Y standard source reported by the IAEA, and they were considered satisfactory. (author)

  15. Evaluation of thermoluminescent dosimeters using water equivalent phantoms for application in clinical electrons beams dosimetry

    International Nuclear Information System (INIS)

    Bravim, Amanda

    2010-01-01

    The dosimetry in Radiotherapy provides the calibration of the radiation beam as well as the quality control of the dose in the clinical routine. Its main objective is to determine with greater accuracy the dose absorbed by the tumor. This study aimed to evaluate the behavior of three thermoluminescent dosimeters for the clinical electron beam dosimetry. The performance of the calcium sulfate detector doped with dysprosium (CaSO 4 : Dy) produced by IPEN was compared with two dosimeters commercially available by Harshaw. Both are named TLD-100, however they differ in their dimensions. The dosimeters were evaluated using water, solid water (RMI-457) and PMMA phantoms in different exposure fields for 4, 6, 9, 12 and 16 MeV electron beam energies. It was also performed measurements in photon beams of 6 and 15 MV (2 and 5 MeV) only for comparison. The dose-response curves were obtained for the 60 Co gamma radiation in air and under conditions of electronic equilibrium, both for clinical beam of photons and electrons in maximum dose depths. The sensitivity, reproducibility, intrinsic efficiency and energy dependence response of dosimeters were studied. The CaSO 4 : Dy showed the same behavior of TLD-100, demonstrating only an advantage in the sensitivity to the beams and radiation doses studied. Thus, the dosimeter produced by IPEN can be considered a new alternative for dosimetry in Radiotherapy departments. (author)

  16. Fatal defect in computerized glow curve deconvolution of thermoluminescence

    International Nuclear Information System (INIS)

    Sakurai, T.

    2001-01-01

    The method of computerized glow curve deconvolution (CGCD) is a powerful tool in the study of thermoluminescence (TL). In a system where the plural trapping levels have the probability of retrapping, the electrons trapped at one level can transfer from this level to another through retrapping via the conduction band during reading TL. However, at present, the method of CGCD has no affect on the electron transition between the trapping levels; this is a fatal defect. It is shown by computer simulation that CGCD using general-order kinetics thus cannot yield the correct trap parameters. (author)

  17. On the set up of a thermoluminescent dosimetric system

    International Nuclear Information System (INIS)

    Furetta, C.

    2000-01-01

    In this work are treated the following features: Introduction to the thermoluminescent dosimetric systems, their prerequisites, Initialisation procedure, Batch homogeneity, Procedure for batch homogeneity (IEC), Reference and field dosimeters, Thermal treatments and its general considerations, as well as its initialisation treatment, erasing treatment or standard annealing (also called pre-irradiation annealing), post-irradiation or pre-readout annealing. Also is presented the performance of the annealing study, with its suggested procedures such as: a first and second procedures. Finally, it is showed about experimental data of the annealing treatments and its diagrams. (Author)

  18. Thermoluminescence of the Z centre in Mg-doped KCl

    International Nuclear Information System (INIS)

    Kamavisdar, V.S.; Deshmukh, B.T.

    1980-01-01

    Optical absorption and thermoluminescence measurements on KCl:Mg 2+ are reported. Bleaching in F band introduces a new glow peak at 406 K in the glow curves. A similar peak is observed in microcrystalline powders. When this peak is thermally cleaned, the broadening of the absorption observed in prolonged F bleached crystals is removed. On the basis of these observations, the glow peak at 406 K is tentatively attributed to Z 1 centres. The glow peak at 394 K observed in microcrystalline powders is attributed to a combined effect of deformation and Z 1 centres. (author)

  19. Comparative study of thermoluminescent efficiencies before variation of experimental factors

    International Nuclear Information System (INIS)

    Avila, O.; Estrada, D.; Gonzalez, P.; Rodriguez V, M.; Buenfil, A.E.; Ruiz T, C.; Brandan, M.E.; Gamboa de Buen, I.; Aviles, P.; Horowitz, Y.S.

    2001-01-01

    An investigation for quantifying the influence of varying distinct experimental factors in the measurements of relative thermoluminescent efficiency of 3 MeV protons was realized with respect to gamma radiation in LiF: Mg, Ti. Variations in a dosemeters batch were considered, as presentation, applied thermal treatments and reader equipment. The main conclusion of this work is to emphasize the importance for measuring entire series of experiments in the same laboratory following a protocol defined carefully and using dosemeters of the same batch for obtaining response before charging particle and the response before gamma radiation with identical procedures of baking and reading. (Author)

  20. Performance of thermoluminescent materials for high dose dosimetry

    International Nuclear Information System (INIS)

    Texeira, Maria I.; Cecatti, Sonia G.P.; Caldas, Linda V.E.

    2008-01-01

    Cases involving high-doses of ionizing radiation are becoming increasingly common.The objective of this work was to characterize thermoluminescent materials for the dosimetry of workers exposed to high doses. Samples of TLD-200, TLD-400 and TLD-800 pellets from Thermo Electron Corporation were studied in gamma high-doses. Dose-response curves were obtained for doses between 100 mGy and 100 Gy. The reproducibility, the lower detection limits and dose-response curves were obtained for all three materials. The different kinds of detectors show usefulness for dosimetry of workers exposed accidentally to high doses. (author)

  1. Thermoluminescence measurements of neutron streaming through JET Torus Hall ducts

    OpenAIRE

    Obryk, Barbara; Batistoni, Paola; Conroy, Sean; Syme, Brian D.; Popovichev, Sergey; Stamatelatos, Ion E.; Vasilopoulou, Theodora; Bilski, Paweł; Contributors, JET EFDA

    2014-01-01

    Thermoluminescence detectors (TLD) were used for dose measurements at JET. Several hundreds of LiF detectors of various types, standard LiF:Mg,Ti and highly sensitive LiF:Mg,Cu,P were produced. LiF detectors consisting of natural lithium are sensitive to slow neutrons, their response to neutrons being enhanced by 6Li-enriched lithium or suppressed by using lithium consisting entirely of 7Li. Pairs of 6LiF/7LiF detectors allow distinguishing between neutron/non-neutron components of a radiatio...

  2. On the second kinetic order thermoluminescent glow curves

    International Nuclear Information System (INIS)

    Dang Thanh Luong; Nguyen Hao Quang; Hoang Minh Giang

    1995-01-01

    The kinetic parameters of thermoluminescent material such as CaF 2 -N and CaSO 4 -Dy with the different grain sizes are investigated in detail using the least square method of fitting. It was found that the activation energy E (or trap depth) and peak temperature T m ax are changed with the elapsed time between the irradiation and read-out for the low temperature glow curve peaks. The similar TL glow curve shapes are obtained for the different CaSO 4 -Dy grain size. (author). 7 refs., 5 figs., 2 tabs

  3. Thermoluminescence of Stoichiometric Magnesium-Aluminium Spinel Defects

    International Nuclear Information System (INIS)

    Kobyakov, V.A.; Gritsina, V.T.; Kazarinov, Yu.G.; Volokitin, V.N.

    2005-01-01

    The investigations of thermoluminescence of spinel single crystals MgAl 2 O 4 after UV- and X-ray irradiation was provided by using method of self consisting heating. It was shown, that observed maxima at temperatures of ∼360 and ∼530 K in UV- and green ranges of spectra, respectively, are complex and consist of several strongly overlapping partial maxima. By using method of self consisting heating we have revealed the approximate position of partial maxima, which are included in maxima of ∼360 and ∼530 K, and for some partial maxima there was obtained the order of kinetics, activation energies, and frequency factors

  4. Personnel radiation monitoring by thermoluminescence dosimetry (1995-96)

    International Nuclear Information System (INIS)

    Daw Mi Cho Cho; Daw Yi Yi Khin; Daw San San; U Maung Maung Tin; Daw Hla Hla Win

    2001-01-01

    Personnel radiation monitoring which is the dose assessment of individual doses from external radiation received by radiation workers has been carried out by Thermoluminescence Dosimetry system consisting of a Vinten Toledo TLD reader, LiF dosimeters and associated equipment. The exposed TLD dosimeters were measured by TLD reader and the dose evaluation and dose registration were done on personal computer. Due to the records of 1995-96, most of the radiation workers complied with the permissible dose recommended by IAEA and ICRP 60. (author)

  5. Development of BaSO4:Eu thermoluminescence phosphor

    International Nuclear Information System (INIS)

    Madhusoodanan, U.; Jose, M.T.; Lakshmanan, A.R.

    1999-01-01

    A highly sensitive thermoluminescence (TL) phosphor based on BaSO 4 :Eu was developed following the coprecipitation technique and firing in argon atmosphere at 1123 K. Photoluminescence studies confirm that firing in argon atmosphere instead of air increased the incorporation of Eu ions in 2+ valence state. At low γ-ray doses, its TL sensitivity is nearly 2 to 3 times higher than that of CaSO 4 :Dy phosphor. The other salient features of this BaSO 4 :Eu TL phosphor are a constant glow curve shape and a nearly linear γ-ray dose response

  6. Thermoluminescent determination of prehistoric heat treatment of chert artifacts

    International Nuclear Information System (INIS)

    Melcher, C.L.; Zimmerman, D.W.

    1977-01-01

    In recent years archeologists have become interested in the extent to which prehistoric peoples heat-treated chert prior to shaping it into tools. Thermoluminescent determination of the radiation dose accumulated by an artifact since it was formed or last heated provides a simple, reliable test for such heat treatment. This test can be applied to single artifacts without the need for raw source material for comparison. Results on 25 artifacts from four sites indicate that, for many chert sources, color and luster are not useful indicators of heat treatment by prehistoric peoples

  7. Method of making isodose curve using thermoluminescence dosemeter

    International Nuclear Information System (INIS)

    Bakar Ramain, A.

    1975-01-01

    Line source of 60 Co in the form of needles and tubes are extensively used in radiotherapy in moulds, implants, and intracavitary techniques for the treatment of malignant lesions. It is important to have isodose distributions in tissue for those source for purposes of treatment planning. The isodose distributions have been obtained experimentally by using tinny lithium-fluoride (Lsub(i)F) thermoluminescent dosemeters (TLD) and they are compared to the theoretical results. The distinct advantages of Lsub(i)F (TLD) in such measurements are briefly discussed. (author)

  8. Dating pleistocene fossil coastal sand dunes by thermoluminescence

    International Nuclear Information System (INIS)

    Poupeau, G.; Souza, J.H.; Soliani Junior, E.; Loss, E.L.

    1983-01-01

    It was shown recently that sunlight exposure is able to bleach most of the geological thermoluminescence (TL) of wind transported sediments. This property has been used in an attempt to date dunes from the well developed recent quaternary coastal dunes system of Rio Grande do Sul. Preliminary results presented here, show that TL dating on fossil sand dunes from Rio Grande do Sul should be possible in a time range from present to at least 50.000 yr and possibly more than 100.000 yr. (Author) [pt

  9. Application of thermoluminescence analysis for detection of irradiated foodstuffs

    International Nuclear Information System (INIS)

    Malec-Czechowska, K.; Dancewicz, M.; Szot, Z.

    1996-01-01

    Investigations on the development conditions necessary to obtain reliable results of the detection of irradiated herbs, spices, mushrooms and strawberries by thermoluminescence (Tl) method in whole samples and/or in minerals isolated from them carried out. Tl intensities of whole samples were measured between 40 an 355 C. Threshold values for non-irradiated samples were obtained by multiplying Tl values of control samples by 3 (safety factor). Samples in which Tl intensities were higher than the threshold values were identified as irradiated. In 4 out of 10 kind of herbs and spices examined the results of Tl measurements led to false identification. (author). 14 refs, 1 fig., 5 tabs

  10. Environmental radiation measurements using lithium fluoride thermoluminescence dosemeters

    Energy Technology Data Exchange (ETDEWEB)

    Driscoll, C.M.H.; Green, B.M.R.; McKinlay, A.F.; Richards, D.J. (National Radiological Protection Board, Harwell (UK))

    1984-01-01

    The National Radiological Protection Board is involved in a large scale environmental survey of radiation levels in homes throughout the United Kingdom. Passive radon and gamma ray dosemeters are posted to a representative sample of households. Lithium fluoride thermoluminescence dosemeters are used to assess natural gamma radiation and are left in the measurement location for a period of six months before being returned to the Board for processing. As a preliminary to the national survey, the Board has been engaged on several limited surveys in regions of igneous and sedimentary geology. Experience gained in these limited surveys and from standardisation studies using environmental dosemeters are reported.

  11. Development of BaSO sub 4 :Eu thermoluminescence phosphor

    CERN Document Server

    Madhusoodanan, U; Lakshmanan, A R

    1999-01-01

    A highly sensitive thermoluminescence (TL) phosphor based on BaSO sub 4 :Eu was developed following the coprecipitation technique and firing in argon atmosphere at 1123 K. Photoluminescence studies confirm that firing in argon atmosphere instead of air increased the incorporation of Eu ions in 2+ valence state. At low gamma-ray doses, its TL sensitivity is nearly 2 to 3 times higher than that of CaSO sub 4 :Dy phosphor. The other salient features of this BaSO sub 4 :Eu TL phosphor are a constant glow curve shape and a nearly linear gamma-ray dose response.

  12. Detecting irradiation of strawberries by means of thermoluminescence measurement

    International Nuclear Information System (INIS)

    Heide, L.; Guggenberger, R.; Boegl, K.W.

    1989-01-01

    Investigations into the origin of the thermoluminescence (TL) have shown that this effect is due to trace amounts of mineral particulates adhering to the irradiated material. This result and own experience have led to the development of the TL-based method for post-factum detection of an irradiation of strawberries. In addition to the analysis of whole fruits, a method has been tested that proceeds via separation of adhering matter to separate TL analysis of the particulates. The results obtained so far show no difference or improvement as compared to whole-fruit TL analysis. (orig./MG) [de

  13. Exoemission and thermoluminescence from human enamel and shark enameloid

    International Nuclear Information System (INIS)

    Davies, J.E.

    1983-01-01

    Simultaneous measurements of exoelectron emission and thermoluminescence from powdered biological apatites, which have not been chemically or thermally pretreated, are reported. Recycling, that is, consecutive irradiation and non-isothermal scanning, is shown to change both the form of the glow curves and emissivity of samples. Two biological apatites of the hydroxyapatite type (human enamel) and fluorapatite type (shark enameloid) are compared. Although their initial glow curves are different, recycling renders the glow curves similar suggesting that the defects involved are a product of the host lattice. The relevance of exoemission as a ''fingerprinting'' technique for biologically reactive material is discussed. (author)

  14. 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)

  15. Thermoluminescence studies having applications to geology and archaeometry

    International Nuclear Information System (INIS)

    Levy, P.N.

    1978-01-01

    Mineral thermoluminescence (TL) studies, undertaken as geophysics investigations, appear to have archaeometric applications. Measurements were made with equipment which records TL emission spectra at closely spaced temperatures. Carbonate rock containing lead-zinc deposits exhibit radiation induced TL against distance-from-ore patterns useful for mineral exploration and locating worked-out deposits. The feldspar albite has second-order TL kinetics, which can introduce dating errors. Heat induced changes in the albite TL emission spectra could be used as a paleotemperature indicator. Quartz remembers previous exposure to radiation, a property influencing TL intensity against dose curves but useful for uranium exploration

  16. Dosimetry Measurements around the Angiography Units Using Thermoluminescence Detectors (TLD)

    International Nuclear Information System (INIS)

    Salah El-den, T.; Shahein, A.Y.; Gomaa, M.A.

    2008-01-01

    The thermoluminescent dosimeters (TLDs) are widely used not only in the field of personnel monitoring (dosimetry) service for ionizing radiation to medical, and research communities, but also for measurements of X-rays emitted from different angiography's unit. Measurements ionizing radiation around the bed area during cardiac catheterization procedures using X-rays was measured. TLD Badges used to determine the annual effective doses, the safe distance for the staff to minimize radiation exposure and the effectiveness of shield and used leaded apron. The results indicated that annual effective dose for by angiography cardiac Catheterization room may exceed the limits

  17. Thermoluminescent characteristics of ZrO2:Nd films

    International Nuclear Information System (INIS)

    Vera B, G.; Rivera M, T.; Azorin N, J.; Falcony G, C.; Garcia H, M.; Martinez S, E.

    2002-01-01

    In this work it is exposed the obtained results after analysing the photo luminescent and thermoluminescent characteristics of activated zirconium oxide with neodymium (ZrO 2 :Nd) and its possible application in the UV radiation dosimetry. The realized experiments had as objective to study the characteristics such as the optimum thermal erased treatment, the influence of light on the response, the response depending on the wavelength, the fadeout of the information, the temperature effect, the response depending on the time and the recurring of the response. The results show that the ZrO 2 :Nd is a promising material to be used as Tl dosemeter for the UV radiation. (Author)

  18. Macroscopic polarization and thermoluminescence of barium niobate - sodium niobate

    International Nuclear Information System (INIS)

    Gorban', I.S.; Gumenyuk, A.F.; Omel'yanenko, V.A.

    1989-01-01

    Thermoluminescence (TL) of initial and thermally treated purposely undoped crystals of barium niobate - sodium has been studied within 85-400 K. The TL intensity is found to depend on the temperature to which the sample has been heated. A conclusion is drawn that nonstationarity of the TL properties is due to slowly occuring processes of compensation of pyrocharge, which depend on the temperatural prehistory of the sample. A mechanism of the traps transformation in a strong pyrofield of high-impedance crystals is discussed

  19. Thermoluminescence in KBr:D electron irradiated at room temperature

    International Nuclear Information System (INIS)

    Paredes Campoy, J.C.; Lopez Carranza, E.

    1991-07-01

    The thermoluminescence of KBr:D samples electron irradiated at room temperature after thermal annealing at 673 K for 1 hour have been studied in the temperature range 360-730 K. The experimental TL-curve was discomposed by computer analysis in seven overlapping TL peaks, giving for them the order of the kinetics of thermal stimulation, the activation energy, the frequency factor, the relative values of the electronic concentration in traps at the initial heating temperature and the temperature at the maximum of the peak. (author). 18 refs, 1 fig., 3 tabs

  20. Using albedo to reform wind erosion modelling, mapping and monitoring

    Science.gov (United States)

    Chappell, Adrian; Webb, Nicholas P.

    2016-12-01

    Wind erosion and dust emission models are used to assess the impacts of dust on radiative forcing in the atmosphere, cloud formation, nutrient fertilisation and human health. The models are underpinned by a two-dimensional geometric property (lateral cover; L) used to characterise the three-dimensional aerodynamic roughness (sheltered area or wakes) of the Earth's surface and calibrate the momentum it extracts from the wind. We reveal a fundamental weakness in L and demonstrate that values are an order of magnitude too small and significant aerodynamic interactions between roughness elements and their sheltered areas have been omitted, particularly under sparse surface roughness. We describe a solution which develops published work to establish a relation between sheltered area and the proportion of shadow over a given area; the inverse of direct beam directional hemispherical reflectance (black sky albedo; BSA). We show direct relations between shadow and wind tunnel measurements and thereby provide direct calibrations of key aerodynamic properties. Estimation of the aerodynamic parameters from albedo enables wind erosion assessments over areas, across platforms from the field to airborne and readily available satellite data. Our new approach demonstrated redundancy in existing wind erosion models and thereby reduced model complexity and improved fidelity. We found that the use of albedo enabled an adequate description of aerodynamic sheltering to characterise fluid dynamics and predict sediment transport without the use of a drag partition scheme (Rt) or threshold friction velocity (u∗t). We applied the calibrations to produce global maps of aerodynamic properties which showed very similar spatial patterns to each other and confirmed the redundancy in the traditional parameters of wind erosion modelling. We evaluated temporal patterns of predicted horizontal mass flux at locations across Australia which revealed variation between land cover types that would not

  1. Bedtime routines child wellbeing & development.

    Science.gov (United States)

    Kitsaras, George; Goodwin, Michaela; Allan, Julia; Kelly, Michael P; Pretty, Iain A

    2018-03-21

    Bedtime routines has shown important associations with areas associated with child wellbeing and development. Research into bedtime routines is limited with studies mainly focusing on quality of sleep. The objectives of the present study were to examine the relationship between bedtime routines and a variety of factors associated with child wellbeing and to examine possible determinants of bedtime routines. A total of 50 families with children between 3 and 5 years old took part in the study. Data on bedtime routines, parenting styles, school readiness, children's dental health, and executive function were collected. Children in families with optimal bedtime routines showed better performance in terms of executive function, specifically working memory (t (44)= - 8.51, p ≤ .001), inhibition and attention (t (48)= - 9.70, p ≤ .001) and cognitive flexibility (t (48)= - 13.1, p ≤ .001). Also, children in households with optimal bedtime routines scored higher in their readiness for school (t (48)= 6.92, p ≤ .001) and had better dental health (U = 85.5, p = .011). Parents in households with suboptimal bedtime routines showed worse performance on all measures of executive function including working memory (t (48)= - 10.47, p ≤ .001), inhibition-attention (t (48)= - 10.50, p ≤ .001) and cognitive flexibility (t (48)= - 13.6, p ≤ .001). Finally, parents with optimal bedtime routines for their children deployed a more positive parenting style in general (i.e. authoritative parenting) compared to those with suboptimal bedtime routines (t (48)= - 6.45, p ≤ .001). The results of the present study highlight the potentially important role of bedtime routines in a variety of areas associated with child wellbeing and the need for further research.

  2. The seasonal cycle of snow cover, sea ice and surface albedo

    Science.gov (United States)

    Robock, A.

    1980-01-01

    The paper examines satellite data used to construct mean snow cover caps for the Northern Hemisphere. The zonally averaged snow cover from these maps is used to calculate the seasonal cycle of zonally averaged surface albedo. The effects of meltwater on the surface, solar zenith angle, and cloudiness are parameterized and included in the calculations of snow and ice albedo. The data allows a calculation of surface albedo for any land or ocean 10 deg latitude band as a function of surface temperature ice and snow cover; the correct determination of the ice boundary is more important than the snow boundary for accurately simulating the ice and snow albedo feedback.

  3. Changes in the Albedo of the Pegasus and Phoenix Runways, 2000-2017

    Science.gov (United States)

    2017-07-18

    by the net heat transfer into the runway surface during the brief but intense peak of austral summer. The flux of downwelling shortwave solar energy...snow; and as ERDC/CRREL TR-17-10 2 mentioned above, the presence of melt water in the snow further reduces albedo and increases heating of the snow...interpolating over all possible angles, end member albedo cases (“white sky” and “black sky”) can be modeled . The actual albedo or “blue sky” albedo falls

  4. The importance of snow albedo for ice sheet evolution over the last glacial cycle

    Directory of Open Access Journals (Sweden)

    M. Willeit

    2018-05-01

    Full Text Available The surface energy and mass balance of ice sheets strongly depends on the amount of solar radiation absorbed at the surface, which is mainly controlled by the albedo of snow and ice. Here, using an Earth system model of intermediate complexity, we explore the role played by surface albedo for the simulation of glacial cycles. We show that the evolution of the Northern Hemisphere ice sheets over the last glacial cycle is very sensitive to the representation of snow albedo in the model. It is well known that the albedo of snow depends strongly on snow grain size and the content of light-absorbing impurities. Excluding either the snow aging effect or the dust darkening effect on snow albedo leads to an excessive ice build-up during glacial times and consequently to a failure in simulating deglaciation. While the effect of snow grain growth on snow albedo is well constrained, the albedo reduction due to the presence of dust in snow is much more uncertain because the light-absorbing properties of dust vary widely as a function of dust mineral composition. We also show that assuming slightly different optical properties of dust leads to very different ice sheet and climate evolutions in the model. Conversely, ice sheet evolution is less sensitive to the choice of ice albedo in the model. We conclude that a proper representation of snow albedo is a fundamental prerequisite for a successful simulation of glacial cycles.

  5. Microfoundations of Routines and Capabilities

    DEFF Research Database (Denmark)

    Felin, Teppo; Foss, Nicolai Juul; Heimriks, Koen H.

    We discuss the microfoundations of routines and capabilities, including why a microfoundations view is needed and how it may inform work on organizational and competitive heterogeneity. Building on extant research, we identify three primary categories of micro-level components underlying routines...

  6. Effect of Mineral Composition on Thermoluminescence Analysis of Irradiated Garlics

    International Nuclear Information System (INIS)

    Sookkasem, Atitaya; Wanwisa, Sudprasert; Vitittheeranon, Arag

    2009-07-01

    Full text: Thermoluminescence (TL) is one of the most popular techniques used for identification of irradiated foods such as spices, herbs and dried fruits in accordance with the Codex Standards. TL analysis is based on the determination of TL of adhering or contaminating minerals in foods. This research aimed to study the effect of mineral composition on the TL intensity. The composited minerals were extracted from 3 types of non-irradiated and irradiated garlic powders by sodium polytungstate solution. X-ray diffraction (XRD) spectroscopy was employed to investigate the type and amount of minerals present in garlic powders. TL of separated minerals were analysed using a Harshaw 4500 TL reader. The results showed that the mineral composition of garlic powders was mainly quartz of varying amounts depending on types of garlics. The TL intensity linearly increased with the amount of quartz present in the samples. It can be concluded that the amount of minerals affect the TL intensity which might influence the identification of irradiated tretment of garlics by thermoluminescence

  7. Effect of thermal decomposition of hydroxyapatite on the thermoluminescent response

    International Nuclear Information System (INIS)

    Sandoval C, K. J.; Zarate M, J.; Lemus R, J.; Rivera M, T.

    2014-08-01

    In this work, a study on the thermoluminescence (Tl) induced by gamma radiation in synthetic hydroxyapatite (Hap) annealed at different temperatures obtained by the precipitation method is presented. Synthesis of hydroxyapatite Hap was carried out starting from inorganic precursors [Ca(NO 3 ) 2 ·4H 2 O and (NH 4 ) 2 HPO 4 ]. The precipitate was filtered, washed, dried and then the powder was calcined at different temperatures until the Hap decomposition. The structural and morphological characterization was carried out using both X-ray diffraction (XRD) and scanning electron microscopy (Sem) techniques. Thermoluminescent (Tl) properties of Hap powders were irradiated at different gamma radiation doses. According to X ray diffraction patterns, the tricalcium diphosphate phase (Tcp) appear when the Hap was calcined at 900 grades C. Tl glow curve showed two peaks located at around 200 and 300 grades C, respectively. Tl response as a function of gamma radiation dose was in a wide range from 25 to 100 Gy. The fading of the Tl response at 134 days after irradiation was measured. Experimental results showed that the synthetic hydroxyapatite obtained by precipitation technique may have dosimetric applications when is annealed at temperature of 900 grades C, where the Tcp phase appears and contributes to Tl response, which opens the possibility of using this biomaterials in the area of dosimetry, as they are generally used for biomedical implants. (author)

  8. Thermoluminescence properties of zinc oxide obtained by solution combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Orante B, V. R.; Escobar O, F. M.; Cruz V, C. [Universidad de Sonora, Departamento de Investigacion en Polimeros y Materiales, Apdo. Postal 130, 83000 Hermosillo, Sonora (Mexico); Bernal, R., E-mail: victor.orante@polimeros.uson.mx [Universidad de Sonora, Departamento de Investigacion en Fisica, Apdo. Postal 5-088, 83190 Hermosillo, Sonora (Mexico)

    2014-08-15

    High-dose thermoluminescence dosimetry properties of novel zinc oxide obtained by solution combustion synthesis in a glycine-nitrate process, with a non-stoichiometric value of the elemental stoichiometric coefficient (Φ{sub c}) are presented in this work. Zn O powder samples obtained were annealed afterwards at 900 grades C during 2 h in air. Sintered particles of sizes between ∼ 0.5 and ∼ 2 μm were obtained, according to scanning electron microscopy results. X-ray diffraction indicates the presence of the hexagonal phase of Zn O for the powder samples obtained, before and after thermal annealing, without any remaining nitrate peaks observed. Thermoluminescence glow curves of Zn O obtained after being exposed to beta radiation consists of two maxima; one located at ∼ 149 grades C and another at ∼ 308 grades C, being the latter the dosimetric component of the curve. Dosimetric characterization of non-stoichiometric zinc oxide provided experimental evidence like asymptotic behavior of the Tl signal fading for times greater than 16 h between irradiation and the corresponding Tl readout, as well as the linear behaviour of the dose response without saturation in the dose interval studied (from 12.5 up to 400 Gy). Such characteristics place Zn O phosphors obtained in this work as a promising material for high-dose radiation dosimetry applications (e.g., radiotherapy and food industry). (author)

  9. Thermoluminescent properties of ZnS:Mn nanocrystalline powders

    International Nuclear Information System (INIS)

    Ortiz-Hernández, Arturo Agustín; Méndez García, Víctor Hugo; Pérez Arrieta, María Leticia; Ortega Sígala, José Juan

    2015-01-01

    Thermoluminescent ZnS nanocrystals doped with Mn 2+ ions were synthesized by chemical co-precipitation method. From X-ray diffraction studies it was observed that the synthesized nanoparticles have cubic zinc blende structure with average sizes of about 40–50 nm. Morphology was analyzed by TEM. Photoluminescence studies showed two transitions, one of them close to 396 nm and other close to 598 nm, which is enhanced with increasing dopant concentration, this behavior was also observed in the cathodoluminescence spectrum. The thermoluminescence gamma dose-response has linear behavior over dose range 5–100 mGy, the glow curve structure shows two glow peaks at 436 K and at 518 K that were taken into account to calculate the kinetic parameters using the Computerized Glow Curve Deconvolution procedure. - Highlights: • Nanocrystals in powder of ZnS:Mn were synthesized using the co-precipitation method. • The integrated TL spectra has a linear behavior on the dose range 5–100 mGy of γ-radiation. • The kinetic parameters were obtained by the CGCD procedure. • Results support the possible use of nanocrystalline ZnS:Mn as a new γ-dose nanoTLD

  10. Thermoluminescence as a tool for monitoring ozone-stressed plants

    Energy Technology Data Exchange (ETDEWEB)

    Skotnica, J.; Gilbert, M.; Weingart, I.; Wilhelm, C

    2003-05-01

    Thermoluminescence parameters are more sensitive to ozone than fluorescence parameters (F{sub 0}, F{sub M}, F{sub v}/F{sub M}). - The effect of ozone (6 h, various concentrations from 0 to 350 ppb) on barley (Hordeum vulgare L., cv. Bomi) and tomato (Lycopersicon esculentum L., cv. Yellow Cherry) leaves was investigated in parallel by thermoluminescence (TL) and fluorescence (FL) methods. Several significant changes were found in TL glow curves measured after excitation by one single turnover flash at +2 deg. C in the temperature range from 2 to 170 deg. C immediately after ozone exposure. Contrary to TL, ozone induced only negligible changes in FL parameters F{sub 0}, F{sub M} and F{sub v}/F{sub M}. Measurements done 24 h after ozone exposure showed partial recovery of ozone-induced changes. The extent of recovery was not the same in different parts of TL curves. Fluorescence parameters were not significantly changed. The results demonstrate that TL parameters are more sensitive to ozone than conventially used FL parameters F{sub 0}, F{sub M} and F{sub v}/F{sub M}. Moreover, TL measurements seem to give information not only about the PSII electron transport, but also about the extent of oxidative damage and membrane lipid peroxidation. It is concluded, that TL can be a highly informative tool for monitoring the impact of ozone on plants.

  11. Thermoluminescence: how safe are we? ask the crystals

    International Nuclear Information System (INIS)

    Madiyal, Ananya; Alva, Priyadharshini

    2013-01-01

    Thermoluminescence means 'light emitted from heat'. Thermoluminescent dosimeter (TLD) is a type of radiation measuring instrument used for the measurement of actual dose received by the operator or patient as a result of radiographic exposure. TLD calculates the ionising radiation exposure by measuring the amount of visible light emitted from a crystal in the detector when the crystal is heated. The two types of TLD are Calcium Fluoride type and the Lithium Fluoride type. The former is used for environmental detection of radiation exposure while the latter is used for detection of personal radiation exposure. A TLD card consists of a nickel plated aluminium plate and 3 filters. The equipment used to heat the exposed material and measure the emitted light produced by heat is called TLD reader. It comprises of a heater, a photomultiplier tube and the electronic system. TLD is used to measure the dose received by a patient while undergoing radiotherapy, for radio-diagnosis and as personnel monitoring devices. It has the advantage of being small in size, chemically inert, accurate and gives a reproducible reading. (author)

  12. Thermoluminescence of double fluorides doped with rare earths

    International Nuclear Information System (INIS)

    Azorin N, J.; Sanchez R, A.; Khaidukov, N.M.

    2004-01-01

    In this work the thermoluminescent characteristics of double fluorides K 2 YF 5 , K 2 GdF 5 and K 2 LuF 5 doped are presented with Tb 3+ , studied in the interval of temperature from 30 to 400 C. The materials that presented better answer to the irradiation with particles beta and with ultraviolet light they were the K 2 YF 5 : Tb (1% at. Tb 3+ ) and the K 2 LuF 5 : Tb (1% at. Tb 3+ ); while the K 2 YF 5 : Tb to high concentrations (10% and 20% at. Tb 3+ ) and the K 2 LuF 5 : Tb (1% at. Tb 3+ ) and the K 2 LuF 5 : Tb (1% at. Tb 3+ ) they presented an acceptable answer in front of the gamma radiation. The intensity of the Tl answer induced in these materials is a decisive factor to continue studying its dosimetric characteristics, what allows to consider them as the base for the development of potential materials to use them in the dosimetry of beta particles, of the UV light of the gamma radiation using the thermoluminescence method. (Author)

  13. Thermoluminescent properties of CVD diamond: applications to ionising radiation dosimetry

    International Nuclear Information System (INIS)

    Petitfils, A.

    2007-09-01

    Remarkable properties of synthetic diamond (human soft tissue equivalence, chemical stability, non-toxicity) make this material suitable for medical application as thermoluminescent dosimeter (TLD). This work highlights the interest of this material as radiotherapy TLD. In the first stage of this work, we looked after thermoluminescent (TL) and dosimetric properties of polycrystalline diamond made by Chemically Vapor Deposited (CVD) synthesis. Dosimetric characteristics are satisfactory as TLD for medical application. Luminescence thermal quenching on diamond has been investigated. This phenomenon leads to a decrease of dosimetric TL peak sensitivity when the heating rate increases. The second part of this work analyses the use of synthetic diamond as TLD in radiotherapy. Dose profiles, depth dose distributions and the cartography of an electron beam obtained with our samples are in very good agreement with results from an ionisation chamber. It is clearly shown that CVD) diamond is of interest to check beams of treatment accelerators. The use of these samples in a control of treatment with Intensity Modulated Radiation Therapy underlines good response of synthetic diamond in high dose gradient areas. These results indicate that CVD diamond is a promising material for radiotherapy dosimetry. (author)

  14. Quality control of dosimetric systems using thermoluminescent crystals

    International Nuclear Information System (INIS)

    Mahecha, L.; Plazas, M. C.; Machado, M.; Perea, M. D.

    2006-01-01

    To achieve an optimal tumoral control to prostate cancer in early and locally advanced stages, it is necessary to increase the dose with a low mobility probability at the vesicle an rectal level. This is achieved through conformal radiotherapy. The Instituto Nacional de Cancerologia uses this technique, but two questions arise from the medical-physicists and medical radio-oncologist: In accordance with clinical protocols, the conformal radiotherapy delivers a low dose to the adjacent healthy tissues. What experimental method exists that can prove with certainly the veracity of this affirmation?. And, Do the dosimetric simulation system calculate suitable the dose for each tissues?. Through thermoluminescent dosimetry and the use of a physical simulator,we measured the absorbed dose at the target volume and the adjacent tissues using conformal and conventional radiotherapy. We proved that organs such as the rectum and bladder, receiver a minor dose in conformal radiotherapy, hence reducing their mobility probability. In addition, the readings from the thermoluminescent dosimeters and the doses calculated by the ECLIPSE dosimetric system were compared, concluding that the patient's prescribed dose is effectively delivered as recommended by the quality control program in radiotherapy. (Author)

  15. Oxidation/reduction effects on sapphire thermoluminescent detectors

    International Nuclear Information System (INIS)

    Molnar, G.; Borossay, J.; Suevegh, K.; Vertes, A.

    1998-01-01

    Complete text of publication follows. The thermoluminescence (TL) and thermally stimulated exoemission (TSEE) properties of Al 2 O 3 has been extensively studied during the past 40 years. It has been suggested as a dosemeter for both ultraviolet light and ionising radiation. Nevertheless the connection between the structure (point defects) of alumina and thermally stimulated relaxation processes has not yet been clearly explained. In this work α-Al 2 O 3 single crystal samples were studied in order to determine the mechanism of electron-hole processes of thermoluminescence and thermally stimulated exoelectron emission peaks. Single crystals prepared in highly reducing conditions were treated in different atmospheres (reducing/oxidising) and their optical absorption (after isochronous annealing), fluorescence, positron-annihilation and TL properties were investigated. Changes of optical absorption and positron annihilation spectra of oxidised samples suggest that Schottky-type defect formation occurred - the concentration of Al-vacancies increased while that of O-vacancies decreased. Also we observed the oxidation of Ti 3+ to Ti 4+ . The reduction of an oxidised sample led to the diminution of Al-vacancy concentration while that of O-vacancies has not been changed. This suggest a Frenkel-type cationic defect. We also tried to correlate these changes to changes of TL glow curves and to explain the origin of some TL peaks

  16. Thermoluminescent of induced calcite by gamma and ultraviolet radiation

    International Nuclear Information System (INIS)

    Lima, J.F. de.

    1987-01-01

    Samples of brazilian calcite, exposed to gamma radiation in laboratory and heated at constant rate of 2.7 0 C/s, showed three glow peaks at 150, 250 and 350 0 C in their thermoluminescent emission curves. The analysis of these peaks, using different models, indicated that they follow a second order kinetics; it has been obtained, for the activation energy, 1.3, 1.5 and 1.7 eV, and, for the pre-exponential factors, 8.1 x 10 14 , 6.8 x10 13 and 2.4 x 10 12 s -1 . Although the total thermoluminescent emission has stayed constant, the relative height of glow peaks has changed with the temperature of annealing in the range of 400 to 700 0 C. Exposed samples were also illuminated with ultraviolet light and the resultant curves showed partial or total bleaching or some glow peaks and the growth of peaks at lower temperatures. Samples of virgin calcite, submited to increasing exposures of gamma rays, showed a corresponding enhancement of the optical absorption bands in the range of 25000 to 47000 cm -1 A subsequent illumination of these samples with ultraviolet light produced a decrease of the optical absorption bands at the same range. (author) [pt

  17. Thermoluminescence properties of zinc oxide obtained by solution combustion synthesis

    International Nuclear Information System (INIS)

    Orante B, V. R.; Escobar O, F. M.; Cruz V, C.; Bernal, R.

    2014-08-01

    High-dose thermoluminescence dosimetry properties of novel zinc oxide obtained by solution combustion synthesis in a glycine-nitrate process, with a non-stoichiometric value of the elemental stoichiometric coefficient (Φ c ) are presented in this work. Zn O powder samples obtained were annealed afterwards at 900 grades C during 2 h in air. Sintered particles of sizes between ∼ 0.5 and ∼ 2 μm were obtained, according to scanning electron microscopy results. X-ray diffraction indicates the presence of the hexagonal phase of Zn O for the powder samples obtained, before and after thermal annealing, without any remaining nitrate peaks observed. Thermoluminescence glow curves of Zn O obtained after being exposed to beta radiation consists of two maxima; one located at ∼ 149 grades C and another at ∼ 308 grades C, being the latter the dosimetric component of the curve. Dosimetric characterization of non-stoichiometric zinc oxide provided experimental evidence like asymptotic behavior of the Tl signal fading for times greater than 16 h between irradiation and the corresponding Tl readout, as well as the linear behaviour of the dose response without saturation in the dose interval studied (from 12.5 up to 400 Gy). Such characteristics place Zn O phosphors obtained in this work as a promising material for high-dose radiation dosimetry applications (e.g., radiotherapy and food industry). (author)

  18. A study of the thermoluminescent properties of CVD diamond detectors

    International Nuclear Information System (INIS)

    Marczewska, B.; Bilski, P.; Olko, P.; Rebisz, M.; Nesladek, M.; Waligorski, M.P.R.

    2002-01-01

    A batch of 20 diamond detectors obtained by the chemical vapour deposition (CVD) method at the Institute for Materials Research at the Limburg University, Belgium, was investigated with respect to their thermoluminescent (TL) properties. The investigated detectors demonstrate TL sensitivity similar to that of the standard LiF:Mg, Ti (MTS) thermoluminescent detectors, lack of fading after two weeks from irradiation and apparent linearity of dose response. In spite of the persistent fluctuation of individual detector sensitivity observed in this batch, a new annealing procedure improved the stability of the TL signal. It has been concluded that 1 h annealing at 350 C assures the highest reproducibility for this set of detectors. A 30% discrepancy of the value of the TL signal between individual detectors from the batch may be caused by non-uniform distribution of dopants in the volume of the CVD diamond. A prototype of a planar TL reader equipped with a CCD camera was employed in this investigation. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  19. A preliminary approach to identify irradiated foods by thermoluminescence measurements

    International Nuclear Information System (INIS)

    Shin, Choonshik; Kim, Hyoung-Ook; Lim, Yoongho

    2012-01-01

    Thermoluminescence (TL) is one of the physical methods for the identification of irradiated foods. Among the currently developed methods, TL is the most widely used method for the identification of irradiated foods. However, in order to use this method, silicate minerals should be isolated from food samples. The process for the isolation of silicate minerals is time consuming and laborious. In this work, we have investigated the applicability of the TL method using iron-containing minerals instead of silicate minerals. In the TL analyses of dried spices, TL glow curves of iron-containing minerals showed maximum temperatures between 150 and 250 °C which were the same as those of silicate minerals. The process for the mineral separation of the proposed method is simple, fast, easy, and reliable. Moreover, the analysis results including TL ratio have not shown significant differences compared with the silicate minerals method. As a result, the TL measurements using the iron-containing minerals could be an excellent method for the identification of the irradiated foods, including dried spices. - Highlights: ► A thermoluminescence method using iron-containing minerals is proposed. ► Current method using silicate minerals is time consuming and laborious. ► However, the proposed method is simple, fast, easy, and reliable. ► Analysis results are similar to those of the silicate minerals method.

  20. A theoretical description of complex thermoluminescence curves: 2

    International Nuclear Information System (INIS)

    Kantorovich, L.N.; Fogel, G.M.

    1989-01-01

    Thermoluminescence kinetics is discussed using a model with one type of recombination centre and an arbitrary number of trapping centre types, assuming that electron retrapping is dominant. A distinctive feature of the suggested method is that an integral equation is obtained for the one-time function z(t) through which both the intensity of the thermoluminescence curve (TLC) and the concentration of charge carriers are expressed. Using a series of approximations, which are analysed in detail, analytical solutions of the integral equation are obtained for an arbitrary elementary peak in a complex TLC consisting of a number of slightly overlapping peaks. The comparison of the theoretical results with the numerical ones obtained by the Runge-Kutta method shows that the obtained analytical expression is precise for the first peak and describes the following TLC peaks satisfactorily. The possibility of using the results of the present study for computer division of a complex TLC into elementary components, even in the case of considerably overlapping peaks, is also discussed. (author)

  1. Effect of thermal decomposition of hydroxyapatite on the thermoluminescent response

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval C, K. J.; Zarate M, J.; Lemus R, J. [Universidad Michoacana de San Nicolas de Hidalgo, Instituto de Investigaciones Metalurgicas, Ciudad Universitaria, Edificio U, 58060 Morelia, Michoacan (Mexico); Rivera M, T., E-mail: karlasandovalc@gmail.com [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico)

    2014-08-15

    In this work, a study on the thermoluminescence (Tl) induced by gamma radiation in synthetic hydroxyapatite (Hap) annealed at different temperatures obtained by the precipitation method is presented. Synthesis of hydroxyapatite Hap was carried out starting from inorganic precursors [Ca(NO{sub 3}){sub 2}·4H{sub 2}O and (NH{sub 4}){sub 2}HPO{sub 4}]. The precipitate was filtered, washed, dried and then the powder was calcined at different temperatures until the Hap decomposition. The structural and morphological characterization was carried out using both X-ray diffraction (XRD) and scanning electron microscopy (Sem) techniques. Thermoluminescent (Tl) properties of Hap powders were irradiated at different gamma radiation doses. According to X ray diffraction patterns, the tricalcium diphosphate phase (Tcp) appear when the Hap was calcined at 900 grades C. Tl glow curve showed two peaks located at around 200 and 300 grades C, respectively. Tl response as a function of gamma radiation dose was in a wide range from 25 to 100 Gy. The fading of the Tl response at 134 days after irradiation was measured. Experimental results showed that the synthetic hydroxyapatite obtained by precipitation technique may have dosimetric applications when is annealed at temperature of 900 grades C, where the Tcp phase appears and contributes to Tl response, which opens the possibility of using this biomaterials in the area of dosimetry, as they are generally used for biomedical implants. (author)

  2. Study of a new dosimetric radio-thermoluminescent systems

    International Nuclear Information System (INIS)

    Cazac, T.C.

    1980-01-01

    This is the first Romanian study to investigate conditions to obtain the radio-thermo-luminescent systems: MgB 4 O 7 :A(A-Nd,Sm,Eu,Dy,Tb,Dy+Sm and Tb+Sm) MgF 2 A (A=Mn,Dy,Tb,Sm,Li), their essential dosimetric characters, as well as the (MgF 2 =Mn) thermophosphorus mixture with a ( 6 LiF) lithium target. An investigation was developed upon a new category of radio-thermoluminescent detectors with low radiation energy dependence and fading, magnesjum boride activated by several elements of the lanthanides class (Nd,Sm,Eu,Dy,Tb). A new radio-thermoluminescent dosimetric system with high sensitivity and moderate dependence on energy radiation - (Mnsup(2+)) manganese activated magnesium fluoride - was also studied. The author explored application of investigated detectors MgF 2 =Mn, MgB 4 O 7 =Dy and MgB 4 O 7 :Tb in neutron dosimetry in complex gamma-neutron fields. It is deemed that by using the dosimetric systems reported in the thesis in order to measure gamma, beta and neutron radiation doses, dosimetric control can be ensured both in professional dosimetry and in nuclear accident dosimetry, as well as in various basic and applicative investigations. A modest contribution is thus made towards achieving the national nuclear program through an extension of the thermophosphorus range with practical applications in nuclear radiation dosimetry. (author)

  3. A Multi-Scale Validation Strategy for Albedo Products over Rugged Terrain and Preliminary Application in Heihe River Basin, China

    Directory of Open Access Journals (Sweden)

    Xingwen Lin

    2018-01-01

    Full Text Available The issue for the validation of land surface remote sensing albedo products over rugged terrain is the scale effects between the reference albedo measurements and coarse scale albedo products, which is caused by the complex topography. This paper illustrates a multi-scale validation strategy specified for coarse scale albedo validation over rugged terrain. A Mountain-Radiation-Transfer-based (MRT-based albedo upscaling model was proposed in the process of multi-scale validation strategy for aggregating fine scale albedo to coarse scale. The simulated data of both the reference coarse scale albedo and fine scale albedo were used to assess the performance and uncertainties of the MRT-based albedo upscaling model. The results showed that the MRT-based model could reflect the albedo scale effects over rugged terrain and provided a robust solution for albedo upscaling from fine scale to coarse scale with different mean slopes and different solar zenith angles. The upscaled coarse scale albedos had the great agreements with the simulated coarse scale albedo with a Root-Mean-Square-Error (RMSE of 0.0029 and 0.0017 for black sky albedo (BSA and white sky albedo (WSA, respectively. Then the MRT-based model was preliminarily applied for the assessment of daily MODerate Resolution Imaging Spectroradiometer (MODIS Albedo Collection V006 products (MCD43A3 C6 over rugged terrain. Results showed that the MRT-based model was effective and suitable for conducting the validation of MODIS albedo products over rugged terrain. In this research area, it was shown that the MCD43A3 C6 products with full inversion algorithm, were generally in agreement with the aggregated coarse scale reference albedos over rugged terrain in the Heihe River Basin, with the BSA RMSE of 0.0305 and WSA RMSE of 0.0321, respectively, which were slightly higher than those over flat terrain.

  4. Spring–summer albedo variations of Antarctic sea ice from 1982 to 2009

    International Nuclear Information System (INIS)

    Shao, Zhu-De; Ke, Chang-Qing

    2015-01-01

    This study examined the spring–summer (November, December, January and February) albedo averages and trends using a dataset consisting of 28 years of homogenized satellite data for the entire Antarctic sea ice region and for five longitudinal sectors around Antarctica: the Weddell Sea (WS), the Indian Ocean sector (IO), the Pacific Ocean sector (PO), the Ross Sea (RS) and the Bellingshausen–Amundsen Sea (BS). Time series data of the sea ice concentrations and sea surface temperatures were used to analyse their relations to the albedo. The results indicated that the sea ice albedo increased slightly during the study period, at a rate of 0.314% per decade, over the Antarctic sea ice region. The sea ice albedos in the PO, the IO and the WS increased at rates of 2.599% per decade (confidence level 99.86%), 0.824% per decade and 0.413% per decade, respectively, and the steepest increase occurred in the PO. However, the sea ice albedo in the BS decreased at a rate of −1.617% per decade (confidence level 95.05%) and was near zero in the RS. The spring–summer average albedo over the Antarctic sea ice region was 50.24%. The highest albedo values were mainly found on the continental coast and in the WS; in contrast, the lowest albedo values were found on the outer edge of the sea ice, the RS and the Amery Ice Shelf. The average albedo in the western Antarctic sea ice region was distinctly higher than that in the east. The albedo was significantly positively correlated with sea ice concentration (SIC) and was significantly negatively correlated with sea surface temperature (SST); these scenarios held true for all five longitudinal sectors. Spatially, the higher surface albedos follow the higher SICs and lower SST patterns. The increasing albedo means that Antarctic sea ice region reflects more solar radiation and absorbs less, leading to a decrease in temperature and much snowfall on sea ice, and further resulted in an increase in albedo. Conversely, the decreasing

  5. Impacts of Satellite-Based Snow Albedo Assimilation on Offline and Coupled Land Surface Model Simulations.

    Directory of Open Access Journals (Sweden)

    Tao Wang

    Full Text Available Seasonal snow cover in the Northern Hemisphere is the largest component of the terrestrial cryosphere and plays a major role in the climate system through strong positive feedbacks related to albedo. The snow-albedo feedback is invoked as an important cause for the polar amplification of ongoing and projected climate change, and its parameterization across models is an important source of uncertainty in climate simulations. Here, instead of developing a physical snow albedo scheme, we use a direct insertion approach to assimilate satellite-based surface albedo during the snow season (hereafter as snow albedo assimilation into the land surface model ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms and assess the influences of such assimilation on offline and coupled simulations. Our results have shown that snow albedo assimilation in both ORCHIDEE and ORCHIDEE-LMDZ (a general circulation model of Laboratoire de Météorologie Dynamique improve the simulation accuracy of mean seasonal (October throughout May snow water equivalent over the region north of 40 degrees. The sensitivity of snow water equivalent to snow albedo assimilation is more pronounced in the coupled simulation than the offline simulation since the feedback of albedo on air temperature is allowed in ORCHIDEE-LMDZ. We have also shown that simulations of air temperature at 2 meters in ORCHIDEE-LMDZ due to snow albedo assimilation are significantly improved during the spring in particular over the eastern Siberia region. This is a result of the fact that high amounts of shortwave radiation during the spring can maximize its snow albedo feedback, which is also supported by the finding that the spatial sensitivity of temperature change to albedo change is much larger during the spring than during the autumn and winter. In addition, the radiative forcing at the top of the atmosphere induced by snow albedo assimilation during the spring is estimated to be -2.50 W m-2, the

  6. Spatio-temporal Variability of Albedo and its Impact on Glacier Melt Modelling

    Science.gov (United States)

    Kinnard, C.; Mendoza, C.; Abermann, J.; Petlicki, M.; MacDonell, S.; Urrutia, R.

    2017-12-01

    Albedo is an important variable for the surface energy balance of glaciers, yet its representation within distributed glacier mass-balance models is often greatly simplified. Here we study the spatio-temporal evolution of albedo on Glacier Universidad, central Chile (34°S, 70°W), using time-lapse terrestrial photography, and investigate its effect on the shortwave radiation balance and modelled melt rates. A 12 megapixel digital single-lens reflex camera was setup overlooking the glacier and programmed to take three daily images of the glacier during a two-year period (2012-2014). One image was chosen for each day with no cloud shading on the glacier. The RAW images were projected onto a 10m resolution digital elevation model (DEM), using the IMGRAFT software (Messerli and Grinsted, 2015). A six-parameter camera model was calibrated using a single image and a set of 17 ground control points (GCPs), yielding a georeferencing accuracy of accounting for possible camera movement over time. The reflectance values from the projected image were corrected for topographic and atmospheric influences using a parametric solar irradiation model, following a modified algorithm based on Corripio (2004), and then converted to albedo using reference albedo measurements from an on-glacier automatic weather station (AWS). The image-based albedo was found to compare well with independent albedo observations from a second AWS in the glacier accumulation area. Analysis of the albedo maps showed that the albedo is more spatially-variable than the incoming solar radiation, making albedo a more important factor of energy balance spatial variability. The incorporation of albedo maps within an enhanced temperature index melt model revealed that the spatio-temporal variability of albedo is an important factor for the calculation of glacier-wide meltwater fluxes.

  7. Quantifying the missing link between forest albedo and productivity in the boreal zone

    Science.gov (United States)

    Hovi, Aarne; Liang, Jingjing; Korhonen, Lauri; Kobayashi, Hideki; Rautiainen, Miina

    2016-11-01

    Albedo and fraction of absorbed photosynthetically active radiation (FAPAR) determine the shortwave radiation balance and productivity of forests. Currently, the physical link between forest albedo and productivity is poorly understood, yet it is crucial for designing optimal forest management strategies for mitigating climate change. We investigated the relationships between boreal forest structure, albedo and FAPAR using a radiative transfer model called Forest Reflectance and Transmittance model FRT and extensive forest inventory data sets ranging from southern boreal forests to the northern tree line in Finland and Alaska (N = 1086 plots). The forests in the study areas vary widely in structure, species composition, and human interference, from intensively managed in Finland to natural growth in Alaska. We show that FAPAR of tree canopies (FAPARCAN) and albedo are tightly linked in boreal coniferous forests, but the relationship is weaker if the forest has broadleaved admixture, or if canopies have low leaf area and the composition of forest floor varies. Furthermore, the functional shape of the relationship between albedo and FAPARCAN depends on the angular distribution of incoming solar irradiance. We also show that forest floor can contribute to over 50 % of albedo or total ecosystem FAPAR. Based on our simulations, forest albedos can vary notably across the biome. Because of larger proportions of broadleaved trees, the studied plots in Alaska had higher albedo (0.141-0.184) than those in Finland (0.136-0.171) even though the albedo of pure coniferous forests was lower in Alaska. Our results reveal that variation in solar angle will need to be accounted for when evaluating climate effects of forest management in different latitudes. Furthermore, increasing the proportion of broadleaved trees in coniferous forests is the most important means of maximizing albedo without compromising productivity: based on our findings the potential of controlling forest

  8. Simulation and Analysis of Topographic Effect on Land Surface Albedo over Mountainous Areas

    Science.gov (United States)

    Hao, D.; Wen, J.; Xiao, Q.

    2017-12-01

    Land surface albedo is one of the significant geophysical variables affecting the Earth's climate and controlling the surface radiation budget. Topography leads to the formation of shadows and the redistribution of incident radiation, which complicates the modeling and estimation of the land surface albedo. Some studies show that neglecting the topography effect may lead to significant bias in estimating the land surface albedo for the sloping terrain. However, for the composite sloping terrain, the topographic effects on the albedo remain unclear. Accurately estimating the sub-topographic effect on the land surface albedo over the composite sloping terrain presents a challenge for remote sensing modeling and applications. In our study, we focus on the development of a simplified estimation method for land surface albedo including black-sky albedo (BSA) and white-sky albedo (WSA) of the composite sloping terrain at a kilometer scale based on the fine scale DEM (30m) and quantitatively investigate and understand the topographic effects on the albedo. The albedo is affected by various factors such as solar zenith angle (SZA), solar azimuth angle (SAA), shadows, terrain occlusion, and slope and aspect distribution of the micro-slopes. When SZA is 30°, the absolute and relative deviations between the BSA of flat terrain and that of rugged terrain reaches 0.12 and 50%, respectively. When the mean slope of the terrain is 30.63° and SZA=30°, the absolute deviation of BSA caused by SAA can reach 0.04. The maximal relative and relative deviation between the WSA of flat terrain and that of rugged terrain reaches 0.08 and 50%. These results demonstrate that the topographic effect has to be taken into account in the albedo estimation.

  9. Evaluation of Operational Albedo Algorithms For AVHRR, MODIS and VIIRS: Case Studies in Southern Africa

    Science.gov (United States)

    Privette, J. L.; Schaaf, C. B.; Saleous, N.; Liang, S.

    2004-12-01

    Shortwave broadband albedo is the fundamental surface variable that partitions solar irradiance into energy available to the land biophysical system and energy reflected back into the atmosphere. Albedo varies with land cover, vegetation phenological stage, surface wetness, solar angle, and atmospheric condition, among other variables. For these reasons, a consistent and normalized albedo time series is needed to accurately model weather, climate and ecological trends. Although an empirically-derived coarse-scale albedo from the 20-year NOAA AVHRR record (Sellers et al., 1996) is available, an operational moderate resolution global product first became available from NASA's MODIS sensor. The validated MODIS product now provides the benchmark upon which to compare albedo generated through 1) reprocessing of the historic AVHRR record and 2) operational processing of data from the future National Polar-Orbiting Environmental Satellite System's (NPOESS) Visible/Infrared Imager Radiometer Suite (VIIRS). Unfortunately, different instrument characteristics (e.g., spectral bands, spatial resolution), processing approaches (e.g., latency requirements, ancillary data availability) and even product definitions (black sky albedo, white sky albedo, actual or blue sky albedo) complicate the development of the desired multi-mission (AVHRR to MODIS to VIIRS) albedo time series -- a so-called Climate Data Record. This presentation will describe the different albedo algorithms used with AVHRR, MODIS and VIIRS, and compare their results against field measurements collected over two semi-arid sites in southern Africa. We also describe the MODIS-derived VIIRS proxy data we developed to predict NPOESS albedo characteristics. We conclude with a strategy to develop a seamless Climate Data Record from 1982- to 2020.

  10. Monitoring land surface albedo and vegetation dynamics using high spatial and temporal resolution synthetic time series from Landsat and the MODIS BRDF/NBAR/albedo product

    Science.gov (United States)

    Wang, Zhuosen; Schaaf, Crystal B.; Sun, Qingsong; Kim, JiHyun; Erb, Angela M.; Gao, Feng; Román, Miguel O.; Yang, Yun; Petroy, Shelley; Taylor, Jeffrey R.; Masek, Jeffrey G.; Morisette, Jeffrey T.; Zhang, Xiaoyang; Papuga, Shirley A.

    2017-07-01

    Seasonal vegetation phenology can significantly alter surface albedo which in turn affects the global energy balance and the albedo warming/cooling feedbacks that impact climate change. To monitor and quantify the surface dynamics of heterogeneous landscapes, high temporal and spatial resolution synthetic time series of albedo and the enhanced vegetation index (EVI) were generated from the 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) operational Collection V006 daily BRDF/NBAR/albedo products and 30 m Landsat 5 albedo and near-nadir reflectance data through the use of the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM). The traditional Landsat Albedo (Shuai et al., 2011) makes use of the MODIS BRDF/Albedo products (MCD43) by assigning appropriate BRDFs from coincident MODIS products to each Landsat image to generate a 30 m Landsat albedo product for that acquisition date. The available cloud free Landsat 5 albedos (due to clouds, generated every 16 days at best) were used in conjunction with the daily MODIS albedos to determine the appropriate 30 m albedos for the intervening daily time steps in this study. These enhanced daily 30 m spatial resolution synthetic time series were then used to track albedo and vegetation phenology dynamics over three Ameriflux tower sites (Harvard Forest in 2007, Santa Rita in 2011 and Walker Branch in 2005). These Ameriflux sites were chosen as they are all quite nearby new towers coming on line for the National Ecological Observatory Network (NEON), and thus represent locations which will be served by spatially paired albedo measures in the near future. The availability of data from the NEON towers will greatly expand the sources of tower albedometer data available for evaluation of satellite products. At these three Ameriflux tower sites the synthetic time series of broadband shortwave albedos were evaluated using the tower albedo measurements with a Root Mean Square Error (RMSE) less than 0.013 and a

  11. Design and development of low cost thermoluminescence measurement system using PIC16F877 microcontroller

    International Nuclear Information System (INIS)

    Neelamegam, P; Rajendran, A

    2006-01-01

    A real time microcontroller based thermoluminescence system has been developed to measure light intensity and temperature and to control linear heating. This instruments permits to conduct investigations on thermoluminescent materials, such as alkali halides, phosphors and related compounds, which have important applications in materials science and in dosimetry. A low cost dedicated PIC16F877 based microcontroller board was employed for the hardware. The detail of its interface and software to measure thermoluminescence and to send data to PC is explained in this paper

  12. Design and development of low cost thermoluminescence measurement system using PIC16F877 microcontroller

    Energy Technology Data Exchange (ETDEWEB)

    Neelamegam, P [Department of Electronics and Instrumentation Engineering, Shunmuga Arts, Science, Technology and Research Academy (SASTRA), Deemed University, Thanjavur-613 402, Tamil Nadu (India); Rajendran, A [PG and Research Department of Applied Physics, Nehru Memorial College (Autonomous), Puthanampatti-621 007, Tiruchirappalli, Tamil Nadu (India)

    2006-05-15

    A real time microcontroller based thermoluminescence system has been developed to measure light intensity and temperature and to control linear heating. This instruments permits to conduct investigations on thermoluminescent materials, such as alkali halides, phosphors and related compounds, which have important applications in materials science and in dosimetry. A low cost dedicated PIC16F877 based microcontroller board was employed for the hardware. The detail of its interface and software to measure thermoluminescence and to send data to PC is explained in this paper.

  13. The AKARI IRC asteroid flux catalogue: updated diameters and albedos

    Science.gov (United States)

    Alí-Lagoa, V.; Müller, T. G.; Usui, F.; Hasegawa, S.

    2018-05-01

    The AKARI IRC all-sky survey provided more than twenty thousand thermal infrared observations of over five thousand asteroids. Diameters and albedos were obtained by fitting an empirically calibrated version of the standard thermal model to these data. After the publication of the flux catalogue in October 2016, our aim here is to present the AKARI IRC all-sky survey data and discuss valuable scientific applications in the field of small body physical properties studies. As an example, we update the catalogue of asteroid diameters and albedos based on AKARI using the near-Earth asteroid thermal model (NEATM). We fit the NEATM to derive asteroid diameters and, whenever possible, infrared beaming parameters. We fit groups of observations taken for the same object at different epochs of the survey separately, so we compute more than one diameter for approximately half of the catalogue. We obtained a total of 8097 diameters and albedos for 5170 asteroids, and we fitted the beaming parameter for almost two thousand of them. When it was not possible to fit the beaming parameter, we used a straight line fit to our sample's beaming parameter-versus-phase angle plot to set the default value for each fit individually instead of using a single average value. Our diameters agree with stellar-occultation-based diameters well within the accuracy expected for the model. They also match the previous AKARI-based catalogue at phase angles lower than 50°, but we find a systematic deviation at higher phase angles, at which near-Earth and Mars-crossing asteroids were observed. The AKARI IRC All-sky survey is an essential source of information about asteroids, especially the large ones, since, it provides observations at different observation geometries, rotational coverages and aspect angles. For example, by comparing in more detail a few asteroids for which dimensions were derived from occultations, we discuss how the multiple observations per object may already provide three

  14. Gonadal dose in routine diagnostic examinations

    International Nuclear Information System (INIS)

    Weber, J.; Koen, J.A.; Akkermans, J.A.

    1974-01-01

    Gonadal doses caused by stray radiation produced during radiodiagnostic investigations were measured with thermoluminescent dosemeters in various hospitals in the Netherlands. Significantly different gonadal doses were measured depending upon the hospital where the investigations were carried out. The mean dose of an examination type in one country can only be determined with any accuracy if measurements in a large number of hospitals are performed

  15. Growing season carries stronger contributions to albedo dynamics on the Tibetan plateau.

    Science.gov (United States)

    Tian, Li; Chen, Jiquan; Zhang, Yangjian

    2017-01-01

    The Tibetan Plateau has experienced higher-than-global-average climate warming in recent decades, resulting in many significant changes in ecosystem structure and function. Among them is albedo, which bridges the causes and consequences of land surface processes and climate. The plateau is covered by snow/ice and vegetation in the non-growing season (nGS) and growing season (GS), respectively. Based on the MODIS products, we investigated snow/ice cover and vegetation greenness in relation to the spatiotemporal changes of albedo on the Tibetan Plateau from 2000 through 2013. A synchronous relationship was found between the change in GSNDVI and GSalbedo over time and across the Tibetan landscapes. We found that the annual average albedo had a decreasing trend, but that the albedo had slightly increased during the nGS and decreased during the GS. Across the landscapes, the nGSalbedo fluctuated in a synchronous pattern with snow/ice cover. Temporally, monthly snow/ice coverage also had a high correspondence with albedo, except in April and October. We detected clear dependencies of albedo on elevation. With the rise in altitude, the nGSalbedo decreased below 4000 m, but increased for elevations of 4500-5500 m. Above 5500 m, the nGSalbedo decreased, which was in accordance with the decreased amount of snow/ice coverage and the increased soil moisture on the plateau. More importantly, the decreasing albedo in the most recent decade appeared to be caused primarily by lowered growing season albedo.

  16. Variation in foliar nitrogen and albedo in response to nitrogen fertilization and elevated CO2

    Science.gov (United States)

    Haley F. Wicklein; Scott V. Ollinger; Mary E. Martin; David Y. Hollinger; Lucie C. Lepine; Michelle C. Day; Megan K. Bartlett; Andrew D. Richardson; Richard J. Norby

    2012-01-01

    Foliar nitrogen has been shown to be positively correlated with midsummer canopy albedo and canopy near infrared (NIR) reflectance over a broad range of plant functional types (e.g., forests, grasslands, and agricultural lands). To date, the mechanism(s) driving the nitrogen-albedo relationship have not been established, and it is unknown whether factors affecting...

  17. Intercomparison and validation of snow albedo parameterization schemes in climate models

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, Christina A.; Winther, Jan-Gunnar [Norwegian Polar Institute, Tromsoe (Norway)

    2005-09-01

    Snow albedo is known to be crucial for heat exchange at high latitudes and high altitudes, and is also an important parameter in General Circulation Models (GCMs) because of its strong positive feedback properties. In this study, seven GCM snow albedo schemes and a multiple linear regression model were intercompared and validated against 59 years of in situ data from Svalbard, the French Alps and six stations in the former Soviet Union. For each site, the significant meteorological parameters for modeling the snow albedo were identified by constructing the 95% confidence intervals. The significant parameters were found to be: temperature, snow depth, positive degree day and a dummy of snow depth, and the multiple linear regression model was constructed to include these. Overall, the intercomparison showed that the modeled snow albedo varied more than the observed albedo for all models, and that the albedo was often underestimated. In addition, for several of the models, the snow albedo decreased at a faster rate or by a greater magnitude during the winter snow metamorphosis than the observed albedo. Both the temperature dependent schemes and the prognostic schemes showed shortcomings. (orig.)

  18. A new albedo parameterization for use in climate models over the Antarctic ice sheet

    NARCIS (Netherlands)

    Kuipers Munneke, P.|info:eu-repo/dai/nl/304831891; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; Lenaerts, J.T.M.|info:eu-repo/dai/nl/314850163; Flanner, M.G.; Gardner, A.S.; van de Berg, W.J.|info:eu-repo/dai/nl/304831611

    2011-01-01

    A parameterization for broadband snow surface albedo, based on snow grain size evolution, cloud optical thickness, and solar zenith angle, is implemented into a regional climate model for Antarctica and validated against field observations of albedo for the period 1995–2004. Over the Antarctic

  19. The influence of inter-annually varying albedo on regional climate and drought

    KAUST Repository

    Meng, Xianhong

    2013-05-05

    Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate modelling, or using the actual observed albedo which is rarely done. Here, time-varying satellite derived albedo data is used to update the lower boundary condition of the Weather Research and Forecasting regional climate model in order to investigate the influence of observed albedo on regional climate simulations and also potential changes to land-atmosphere feedback over south-east Australia. During the study period from 2000 to 2008, observations show that albedo increased with an increasingly negative precipitation anomaly, though it lagged precipitation by several months. Compared to in-situ observations, using satellite observed albedo instead of the default climatological albedo provided an improvement in the simulated seasonal mean air temperature. In terms of precipitation, both simulations reproduced the drought that occurred from 2002 through 2006. Using the observed albedo produced a drier simulation overall. During the onset of the 2002 drought, albedo changes enhanced the precipitation reduction by 20 % on average, over locations where it was active. The area experiencing drought increased 6.3 % due to the albedo changes. Two mechanisms for albedo changes to impact land-atmosphere drought feedback are investigated. One accounts for the increased albedo, leading to reduced turbulent heat flux and an associated decrease of moist static energy density in the planetary boundary layer; the other considers that enhanced local radiative heating, due to the drought, favours a deeper planetary boundary layer, subsequently decreasing the moist static energy density through entrainment of the free atmosphere. Analysis shows that drought related large-scale changes in the regional climate favour a

  20. Personal neutron monitoring using TLD albedo combined with etched tracks detector

    Energy Technology Data Exchange (ETDEWEB)

    Tsujimura, N.; Momose, T. [Japan Nuclear Cycle Development Institute, Ibarakiken (Japan)

    2002-07-01

    The albedo dosimetry has been carried out in personal neutron monitoring in the MOX fuel plant of JNC Tokai Works, however, it has shortcomings mainly due to the inherently poor energy response. This paper describes our efforts to overcome these difficulties in practical use of albedo dosemeters. The following four subjects are presented: (1) the neutron energy response functions of albedo TLD obtained from the mono-energetic neutron irradiation experiments and the Monte-Carlo calculations, (2) the location- dependent correction factors calculated from the response functions and neutron energy spectra measured in the workplaces, (3) the results of the international personal neutron dosimetry intercomparison program, and (4) the operational comparison program of TLD albedo and etched tracks detector worn by workers engaged in the fabrication process of the MOX fuel plant. Finally, the characteristics of the combination neutron dosemeter using TLD albedo and solid state etched track detector are summarized.

  1. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  2. Calculation of neutron albedo from laminated semiinfinite media

    International Nuclear Information System (INIS)

    Dobrynin, Yu.L.; Mikaehlyan, L.A.; Skorokhvatov, M.D.

    1978-01-01

    A version of a laminated neutron detector with increased efficiency for recording external neutron fluxes by gamma-quanta from neutron capture is considered. The detector comprises two zones. The first zone constitutes an absorbent layer (europium oxide) 0.5 cm thick, and the second one is a moderator (water with gadolinium salt at the concentration of 0.8 g/l). Mono-energetic neutrons fall normally onto the detector surface. Neutron energy varied from 0.1 eV to MeV. The results of calculations of the integral numerical current albedo (INCA) of neutrons by the Monte Carlo method are presented. The INCA dependences on neutron energy are obtained for one moderator with different gadolinium contents; for the absorbent with the moderator containing and lacking the gadolinium. The resultant dependences are indicative of preferential capture of neutrons by the gadolinium in the moderator, this being more desirable for recording neutrons in the (n, γ) reaction

  3. THE STATISTICS OF ALBEDO AND HEAT RECIRCULATION ON HOT EXOPLANETS

    International Nuclear Information System (INIS)

    Cowan, Nicolas B.; Agol, Eric

    2011-01-01

    If both the day-side and night-side effective temperatures of a planet can be measured, it is possible to estimate its Bond albedo, 0 B 0 , and associated uncertainty. We then use a simple model-independent technique to estimate a planet's effective temperature from planet/star flux ratios. We use thermal secondary eclipse measurements-those obtained at λ>0.8 μm-to estimate day-side effective temperatures, T d , and thermal phase variations-when available-to estimate night-side effective temperature. We strongly rule out the 'null hypothesis' of a single A B and ε for all 24 planets. If we allow each planet to have different parameters, we find that low Bond albedos are favored (A B 0 , the day-side effective temperatures of the 24 planets describe a uni-modal distribution. The two biggest outliers are GJ 436b (abnormally hot) and HD 80606b (abnormally cool), and these are the only eccentric planets in our sample. The dimensionless quantity T d /T 0 exhibits no trend with the presence or absence of stratospheric inversions. There is also no clear trend between T d /T 0 and T 0 . That said, the six planets with the greatest sub-stellar equilibrium temperatures (T > 2400 K) have low ε, as opposed to the 18 cooler planets, which show a variety of recirculation efficiencies. This hints that the very hottest transiting giant planets are qualitatively different from the merely hot Jupiters. We propose an explanation of this trend based on how a planet's radiative and advective times scale with temperature: both timescales are expected to be shorter for hotter planets, but the temperature dependence of the radiative timescale is stronger, leading to decreased heat recirculation efficiency.

  4. The Statistics of Albedo and Heat Recirculation on Hot Exoplanets

    Science.gov (United States)

    Cowan, Nicolas B.; Agol, Eric

    2011-03-01

    If both the day-side and night-side effective temperatures of a planet can be measured, it is possible to estimate its Bond albedo, 0 calculate a sub-stellar equilibrium temperature, T 0, and associated uncertainty. We then use a simple model-independent technique to estimate a planet's effective temperature from planet/star flux ratios. We use thermal secondary eclipse measurements—those obtained at λ>0.8 μm—to estimate day-side effective temperatures, T d, and thermal phase variations—when available—to estimate night-side effective temperature. We strongly rule out the "null hypothesis" of a single AB and ɛ for all 24 planets. If we allow each planet to have different parameters, we find that low Bond albedos are favored (AB outliers are GJ 436b (abnormally hot) and HD 80606b (abnormally cool), and these are the only eccentric planets in our sample. The dimensionless quantity T d/T 0 exhibits no trend with the presence or absence of stratospheric inversions. There is also no clear trend between T d/T 0 and T 0. That said, the six planets with the greatest sub-stellar equilibrium temperatures (T > 2400 K) have low ɛ, as opposed to the 18 cooler planets, which show a variety of recirculation efficiencies. This hints that the very hottest transiting giant planets are qualitatively different from the merely hot Jupiters. We propose an explanation of this trend based on how a planet's radiative and advective times scale with temperature: both timescales are expected to be shorter for hotter planets, but the temperature dependence of the radiative timescale is stronger, leading to decreased heat recirculation efficiency.

  5. Thermoluminescence results on slices from a Hiroshima tile UHFSFT03

    International Nuclear Information System (INIS)

    Stoneham, Doreen

    1987-01-01

    As was reported at the May 1984 Utah thermoluminescence (TL) workshop, high fired tiles and porcelain fragments can be sliced into 200 μm sections with constant surface area. When conventional pre-dose measurements were carried out on these slices the doses evaluated were in good agreement with results obtained by other workers using conventional quartz separation techniques. There are several advantages in using slices. First, less sample is needed as about 50 consecutive slices can be cut from a block measuring typically 1 cm 2 cross section and 2 cm in length. There are no problems with securing grains to the plate or loss of grains during measurement. Hypothetically there is less damage to the grains when they are cut slowly under cold water than when they are crushed. The disadvantage is that other minerals besides quartz are present in the slice and the signal is weaker than that obtained using quartz inclusions

  6. Physical principles of thermoluminescence and recent developments in its measurement

    International Nuclear Information System (INIS)

    Levy, P.W.

    1974-01-01

    The physical principles which are the basis of thermoluminescence techniques for dating and authenticating archaeological and fine art objects are described in non-technical terms. Included is a discussion of the interaction of alpha particles, beta rays, i.e., energetic electrons, and gamma rays with solids, particularly electron-hole ion pair formation, and the trapping of charges by crystal imperfections. Also described is the charge-release process induced by heating and the accompanying emission of luminescence resulting from charge recombination and retrapping. The basic procedure for dating and/or authenticating an artifact is described in a ''how it is done'' manner. Lastly, recently developed apparatus is described for simultaneously measuring luminescent light intensity and wavelength and sample temperature. Examples of studies made with this ''3-D'' apparatus are given and applications to dating and authenticating are described. (U.S.)

  7. Detection of irradiated potato and garlic by thermoluminescence measurement

    International Nuclear Information System (INIS)

    Chung, H.W.; Kwon, J.H.

    1998-01-01

    Potato and garlic irradiated with gamma ray and electron beam at sprout-inhibition doses, 0.15 and 0.30 kGy were subjected to the detection whether they are irradiated or not by measuring thermoluminescence(TL) for the minerals adhering to the samples. Minerals extracted from the samples showed a high correlation coefficients between absorbed doses and corresponding TL responses. Nonirradiated samples, however, did not exhibit characteristic TL glowcurves. Major glowcurve peaks were observed at 200 to in all irradiated samples. TL intensity was proportional to irradiated doses, but it varied with the samples tested even at the same dose. It can be concluded from the results that detection of irradiated potato and garlic is possible by measuring TL for extracted minerals from the unknown samples

  8. Dating of ancient Egyptian pottery using the thermoluminescence technique

    Science.gov (United States)

    El-Fiki, S. A.; Abdel-Wahab, M. S.; El-Faramawy, N.; El-Fiki, M. A.

    1994-10-01

    In the course of the dating of Egyptian ancient pottery, pottery sherds were collected from three archaeological tombs in the Nazlet El Samman region in the Giza zone (Egypt). The annual dose was measured by the gamma spectroscopic technique as well as thermoluminescence (TL) measurements. The annual dose results obtained using both methods are in quite good agreement with a consistency of 99.69%. The extracted quartz exhibited TL dating peaks at about (305 ± 5)°C and (375 ± 5)°C. The TL dating result is 4301 ± 100 which belongs to the "fourth dynasty" in the Old Kingdom. The obtained ages show that the uncertainties in TL dating using the additive method are much lower than that of archaeologists.

  9. Thermoluminescence under an exponential heating function: I. Theory

    International Nuclear Information System (INIS)

    Kitis, G; Chen, R; Pagonis, V; Carinou, E; Kamenopoulou, V

    2006-01-01

    Constant temperature hot gas readers are widely employed in thermoluminescence dosimetry. In such readers the sample is heated according to an exponential heating function. The single glow-peak shape derived under this heating condition is not described by the TL kinetics equation corresponding to a linear heating rate. In the present work TL kinetics expressions, for first and general order kinetics, describing single glow-peak shapes under an exponential heating function are derived. All expressions were modified from their original form of I(n 0 , E, s, b, T) into I(I m , E, T m , b, T) in order to become more efficient for glow-curve deconvolution analysis. The efficiency of all algorithms was extensively tested using synthetic glow-peaks

  10. Solid track detectors used for the dating by thermoluminescence

    International Nuclear Information System (INIS)

    Miallier, D.

    1982-10-01

    A new α counting technic is presented in the field of the thermoluminescent dating method. It is based upon α particles registration in plastic detectors LR-115 Kodak in close contact with archeological or geological samples. The control of etching and counting conditions allowed to improve the usual precision of the detector. The following data are collected: α and β dose rates deposited by Uranium and Thorium series; an approximative value for the Uranium-Thorium ratio; spatial distribution of α emittors within samples and the radon escape rated. This method was used simultaneously with the ''quartz inclusion technic'' to date several samples: volcanic lava flows from the ''Chaine des Puys'' (Center France); the Butte de Clermont basaltic maar; a neolithic ''cardial'' pot-sherd and bricks from a minoaan palace (Mallia, Crete) [fr

  11. Thermoluminescence characterisation of chemical vapour deposited diamond films

    CERN Document Server

    Mazzocchi, S; Bucciolini, M; Cuttone, G; Pini, S; Sabini, M G; Sciortino, S

    2002-01-01

    The thermoluminescence (TL) characteristics of a set of six chemical vapour deposited diamond films have been studied with regard to their use as off-line dosimeters in radiotherapy. The structural characterisation has been performed by means of Raman spectroscopy. Their TL responses have been tested with radiotherapy beams ( sup 6 sup 0 Co photons, photons and electrons from a linear accelerator (Linac), 26 MeV protons from a TANDEM accelerator) in the dose range 0.1-7 Gy. The dosimetric characterisation has yielded a very good reproducibility, a very low dependence of the TL response on the type of particle and independence of the radiation energy. The TL signal is not influenced by the dose rate and exhibits a very low thermal fading. Moreover, the sensitivity of the diamond samples compares favourably with that of standard TLD100 dosimeters.

  12. Current status of thermoluminescence studies on minerals and rocks

    International Nuclear Information System (INIS)

    Sankaran, A.V.; Nambi, K.S.V.; Sunta, C.M.

    1982-01-01

    The usefulness of thermoluminescence (TL) in geological studies is being increasingly recognized, as may be judged from the considerable volume of literature accumulated over the past couple of decades; besides, a number of seminars, conferences and specialists' meetings have also been held on the subject of applied TL. However, these publications lie scattered over several periodicals and conference proceedings and an interested worker finds it difficult to obtain the gist of the contributions in one place. The present authors felt a need for this and have, therefore, attempted to bring together in this Report the current status of TL research about different minerals; applications in the fields of geochronology, ore-prospecting, stratigraphic correlation, geothermometry and other useful areas are also included. (author)

  13. External dosimetry by Thermoluminescent Dosimetry Laboratory - IPEN/CNEN - Brazil

    International Nuclear Information System (INIS)

    Manzoli, Jose Eduardo; Carvalho, Ricardo Nunes

    2001-01-01

    The Thermoluminescence Dosimetry Laboratory, LDT - IPEN/CNEN - Brazil, executes around six thousand TLD readings monthly. It is responsible for the dose evaluation and registration and for all the manufacture process of preparation and sending the dosemeters which are used by IPEN itself, hospitals, industries, town halls, universities, etc. Although prepared to read many kinds of materials, actually the LDT reads only CaSO 4 :Dy detector chips. Chips, heating molds, plastic packaging and almost every material or instrument are made right here at IPEN. The readings are performed in a Bicron Harshaw TLD model 5500, but an old model 2000-AB is ready to be used if necessary. In this work it is presented some features of this important service realized to the IPEN workers and to the community. (author)

  14. The NRPB automated thermoluminescent dosemeter and dose record keeping system

    International Nuclear Information System (INIS)

    Dennis, J.A.; Marshall, T.O.; Shaw, K.B.

    1975-03-01

    This report describes the thermoluminescent personal radiation dosemeter and its associated automated processing equipment, which are being developed by the National Radiological Protection Board, together with the operation of a computerised dosemeter issue and record keeping system. The main justifications for introducing these systems are improvements in the organizational efficiency of the maintenance of individual dose records, a more flexible and accurate dosimetry system, and economics in operational costs. The dosemeter is based on a numbered aluminium plate containing two lithium fluoride in polytetrafluorethylene disks for the measurement of surface and body dose. This dosemeter is wrapped in thin plastic and labelled with the wearer's name and address. On return, the dosemeter is checked automatically for radioactive contamination; it is unwrapped and evaluated; the dose readings are included in the wearer's stored dose record; the dosemeter is annealed and is then available for re-issue to another wearer. Dose reports and warnings are automatically issued to the wearer or his employer. (author)

  15. Thermoluminescence response of gamma-irradiated sesame with mineral dust

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez L, Y. [CSIC, Instituto de Estructura de la Materia, Calle Serrano 121, 28006 Madrid (Spain); Correcher, V. [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Garcia G, J. [CSIC, Museo Nacional de Ciencias Naturales, Calle Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Cruz Z, E., E-mail: y.r.l@csic.es [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior s/n, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2011-10-15

    The thermoluminescence (Tl) emission of minerals isolated from Mexican and Indian sesame seeds appear as a good tool to discern between irradiated and non-irradiated samples. According to the X-ray diffraction and environmental scanning microscope, the adhered dust in both samples is mainly composed by different amounts of quartz and feldspars. These mineral phases exhibit (i) enough sensitivity to ionizing radiation inducing good Tl intensity, (ii) high stability of the Tl signal during the storage of the material (i.e. low fading) and (iii) are thermally and chemically stable. Blind tests performed under laboratory conditions, but simulating industrial preservation processes (similar temperature and moisture, and presence of white light), allows to distinguish between 1 KGy gamma-irradiated and non-irradiated samples even 11000 hours (15 months) after the irradiation proceeding. (Author)

  16. Dating of Chichen Itza ceramics by the method of thermoluminescence

    International Nuclear Information System (INIS)

    Gonzalez M, P.R.; Mendoza A, D.; Cuapio O, L.A.; Ramirez L, A.; Schaaf, P.; Chung, H.

    2005-01-01

    In this work we present some results about thermoluminescent dating of some archaeological ceramic samples belonging to Chichen Itza, Yucatan, Mexico: CH11, CH13, CH14 and CH15. The analysis was realized using the fine grained mode in a Daybreak model 1100 reader Tl System. The radioisotopes that contribute in the accumulate annual dose in ceramic samples ( 40 K, 238 U, 232 Th) were determined by means of techniques such as Energy Dispersive X-ray Spectroscopy (EDS) and Neutron Activation Analysis (NAA), while the artificial irradiation of samples was carried out with a 90 Sr source beta radiation. The resulting mean CH11 ceramic sample was 934 ±45 years old, CH13 was 465 ± 26, CH14 was 888 ± 34 and CH15 was 867 ± 42. These results are in agreement with results obtained through other methods. (Author)

  17. The problem of low thermoluminescence age estimates in geological dating

    International Nuclear Information System (INIS)

    Nambi, K.S.V.

    1983-01-01

    A systematic underestimate of the geological age by the TL technique has been observed in a variety of CaCO 3 samples of Quaternary to Precambrian ages. It is concluded that the TL dating clock in the CaCO 3 lattice stops when the alpha palaeodose =alpha (rad a -1 )x geological age (a) reaches about 100,000 rad. At this dose the natural thermoluminescence reaches perhaps a dynamic equilibrium level determined solely by the alpha activity of the sample. There are indications that the limiting alpha palaeodose beyond which TL dating is invalid is more or less the same for CaSO 4 and silicate samples, and it is convenient to note a limiting value of 3 million for the product of alpha activity (cph from 13.86 cm 2 ) and geological age (a). (author)

  18. Thermoluminescent dosimetry in computed tomography for pediatric patients

    International Nuclear Information System (INIS)

    Medrano S, A. C.; Medina A, O.; Hidalgo T, S.; Azorin N, J.

    2015-10-01

    Computed tomography (CT) in conjunction with interventional radiology, is considered as high-dose radiological procedure, so the optimization of the dose is necessary. Exposure to ionizing radiation in pediatric CT is of particular interest because the children are up to 10 times more sensitive to radiation than adults, the late somatic and genetic effects of radiation. The exposure and risk associated with ionizing radiation in CT is best characterized by the absorbed dose to each organ. Thermoluminescent dosimeters of LiF: Mg, Ti are best suited for this purpose due to its characteristics such as high sensitivity, small size and its equivalence with the tissue. The results of dose measurements -in vivo- to the three types of CT studies (skull, thorax and abdomen) are presented. These results indicate that lower doses were obtained in skull study, while the highest was one of abdomen. (Author)

  19. Dating implications from solar bleaching of thermoluminescence of ancient marble

    International Nuclear Information System (INIS)

    Liritzis, I.; Galloway, R.B.

    1999-01-01

    Measurements of Thermoluminescence (TL) from Greek marble quarried at Paros, Naxos, Pendeli, Hymitos, Thassos, which have been known since ancient time are presented. The results concern i) the solar bleaching of TL, ii) the solar transmission through marble thicknesses up to 16 mm, and iii) the implications for potential dating of ancient carbed marble monuments/objects. The bleaching rate for marbles is very fast during the first hour of exposure. The solar penetration is at least 35 mm for long exposures. Beyond the 2 mm marble slab for exposure times 90-120 hours of sunshine, the residual bleached TL level is not reached. The bleached TL reaches a plateau which serves as the 'zero time' upon which the archaeological TL dose subsequently builds up and gives the age of a marble monument. (author)

  20. Comparison of thermoluminescence detection methods for irradiated spices

    International Nuclear Information System (INIS)

    Kawamura, Y.; Murayama, M.; Uchiyama, S.; Saito, Y.

    1996-01-01

    Thermoluminescence (TL) analysis has been shown to be one of the most applicable methods for the detection of γ-irradiated spices. This analysis was introduced as a detection technique for irradiated spices using the whole sample. It was then found that the origin of the TL response to be mineral dust adhering to the spices. TL measurements on separated minerals and the normalised TL measurement by re-irradiation was then established. This paper details investigations on TL measurements carried out using clean powdered spices stored for one year after being irradiated with doses of 1, 5, 10 and 30 kGy in order to clarify their applicable dose range, the effect of storage and mineral content. The effect of the mineral separation was also studied. (author)

  1. Neodymium oxide: A new thermoluminescent material for gamma dosimetry

    Science.gov (United States)

    Soliman, C.

    2006-10-01

    In the present study thermoluminescence (TL) glow curves of commercial and gamma (0.001 Gy to 100 kGy) exposed neodymium oxide (Nd 2O 3) have been investigated. The commercial glow curve is simple with TL peaks at 310, 350 and 385 °C. The TL sensitivity was enhanced to ˜4.7 times the original value when the investigated material was subject to pre-heating treatment at 800 °C for 1 h. The effect of storage time at room temperature has been monitored for different γ-doses. The combination of good γ-dose response and high stability of defects offer the possibility of applying the investigated material to γ-ray dosimetry in radiotherapy and experimental radiology range.

  2. Intrinsic thermoluminescence of NaCl:Tl in UV dosimetry

    International Nuclear Information System (INIS)

    Barghare, S.P.; Joshi, R.V.; Joshi, T.R.; Kathuria, S.P.

    1982-01-01

    NaCl:Tl(T) phosphor is found to have high intrinsic thermoluminescence (TL) sensitivity to 253.7 nm UV-radiation. The dosimetric glow peak II grows sublinearly with increase in UV dose in the range 10 3 to 10 6 JM -2 . The other requirements of an efficient dosimeter material such as high storage stability, matching of the spectral response of detector tube and TL-emission from phosphor, reproducibility, desirable size and shape, easy availability in powder, pellet and crystal forms at cheaper rates, and repeated re-usability of the same phosphor without much difficulty, etc., are additional factors which strengthen the claim of NaCl:Tl(T) phosphor as UV dosimetric material. It is proposed that present NaCl:Tl(T) material is suitable TL-phosphor for UV dosimetry in the range 10 3 to 10 6 JM -2 . (author)

  3. Hydrothermally synthesized barium fluoride nanocubes for thermoluminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Bhadane, Mahesh S.; Dahiwale, S. S.; Bhoraskar, V. N.; Dhole, S. D., E-mail: sanjay@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune-411007 (India)

    2016-05-23

    In this work, we report a hydrothermally synthesized Dy doped BaF{sub 2} (BaF{sub 2}:Dy) nanocubes and its Thermoluminescence studies. The synthesized BaF{sub 2}:Dy samples was found to posses FCC structure and having average size ~ 60-70 nm, as revealed through X-Ray Diffraction. Cubical morphology having size ~90 nm was observed from TEM analysis. The {sup 60}Co γ- ray irradiated BaF{sub 2}:Dy TL dosimetric experiments shows a pre-dominant single glow peak at 153 °C, indicating a single level trap present as a metastable state. Furthermore, BaF{sub 2}:Dy nanophosphor shows a sharp linear response from 10 Gy to 3 kGy, thus it can be applicable as a gamma dosimeter.

  4. Thermoluminescence emission spectra and optical bleaching of oligoclase

    International Nuclear Information System (INIS)

    Bos, A.J.J.; Piters, T.M.; Ypma, P.J.

    1994-01-01

    Thermoluminescence (TL) spectra of oligoclase samples have been recorded in the temperature range from 300 to 700 K and the wavelength range from 300 to 850 nm. Like other feldspars, oligoclase produces blue (peaking at 460 nm) and red (peaking at 765 nm) emission bands. The maximum of the red emission occurs 20 K lower than that of the blue band. Optical bleaching was performed at wavelengths varying from 360 to 800 nm. Bleaching of artificially irradiated oligoclase causes a decrease of the TL signal. The bleaching efficiency increases with decreasing wavelength. Bleaching does not only influence the height of the glow curve but also the shape. An interesting observation is that the ratio of the blue and red band intensities is not affected by a bleaching procedure. No evidence has been found that bleaching influences the shape of the emission spectra. The correlation between the blue and red bands is discussed. (Author)

  5. Identification of gamma-irradiated Chinese herbs by thermoluminescence analysis

    International Nuclear Information System (INIS)

    Yu Bai; Chinese Academy of Sciences, Changchun; Jilin Medical College, Jilin; WenYue Jiang; Zhongying Liu; He Lin; Changchun University of Traditional Chinese Medicine, Changchun; Zhiqiang Liu

    2014-01-01

    The feasibility of thermoluminescence (TL) to differentiate irradiated Chinese medicinal herbs from non-irradiated was investigated. Thirty different dried Chinese herbs were tested, including root, flower, ramulus, rhizome, cortex, and whole plant samples. Irradiation of Chinese herbs was associated with strong TL peaks at ∼150-250 deg C, while TL curves of non-irradiated herbs had very low intensities above 250 deg C, which was also confirmed by the TL ratio (non-irradiated, TL 1 /TL 2 1 /TL 2 > 0.1) except for sterculia lychnophora, semen cassia, flos inulae, and anemone root. TL ratios of some herbs indicated irradiation (TL 1 /TL 2 > 0.1) even if the irradiated components were as low as 0.1 %. Thus we demonstrated that TL analysis had excellent sensitivity and reliability for the identification of irradiated Chinese herbs. (author)

  6. Assessment of CVD diamond as a thermoluminescence dosemeter material

    International Nuclear Information System (INIS)

    Borchi, E.; Furetta, C.; Leroy, C.

    1996-01-01

    Diamond has a low atomic number (Z = 6) and is therefore essentially soft tissue (Z = 7.4) equivalent. As such, diamond is an attractive material for applications in dosimetry in which the radiation absorption in the sensor material should be as close as possible to that of soft tissue. Synthetic diamond prepared by chemical vapour deposition (CVD) offers an attractive option for this application. The aim of the present work is to report results on the thermoluminescence (TL) properties of CVD diamond samples. The annealing procedures, the linearity of the TL response as a function of dose, a short-term fading experiment and some kinetic properties have been investigated and are reported here. (Author)

  7. Thermoluminescence in medical dosimetry; Termoluminiscencia en dosimetria medica

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, T., E-mail: trivera@ipn.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico)

    2011-10-15

    The dosimetry by thermoluminescence (Tl) is applied in the entire world for the dosimetry of ionizing radiations specially to personal and medical dosimetry. This dosimetry method has been very interesting for measures in vivo because the Tl dosimeters have the advantage of being very sensitive in a very small volume and they are also equivalent to tissue and they do not need additional accessories (for example, cable, electrometer, etc.) The main characteristics of the diverse Tl materials to be used in the radiation measures and practical applications are: the Tl curve, the share homogeneity, the signal stability after the irradiation, precision and exactitude, the response in function with the dose and the energy influence. In this work a brief summary of the advances of the radiations dosimetry is presented by means of the thermally stimulated luminescence and its application to the dosimetry in radiotherapy. (Author)

  8. Auto-regenerative thermoluminescence dating using zircon inclusions

    International Nuclear Information System (INIS)

    Templer, R.H.

    1993-01-01

    Fired ceramics containing zircon inclusions have been dated by allowing the zircons to regenerate their own thermoluminescence (TL) signal, hence auto-regenerative TL dating. The technique is conceptually straightforward. One first measures the TL accrued since the last heating of the material. The zircon grains are then stored for six months and the TL signal regenerated through self-irradiation is measured. Since the internal dose-rate for zircon is dominated by the internal component the age of the sample is simply given by the ratio of the natural to auto-regenerated signal times the laboratory storage period. The technique, however, requires the measurement of a very small auto-regenerated signal, which introduces a number of experimental and physical complications. The methods for overcoming these problems and successfully dating zircons by auto-regeneration are described. (Author)

  9. Thermoluminescence response of gamma-irradiated sesame with mineral dust

    International Nuclear Information System (INIS)

    Rodriguez L, Y.; Correcher, V.; Garcia G, J.; Cruz Z, E.

    2011-10-01

    The thermoluminescence (Tl) emission of minerals isolated from Mexican and Indian sesame seeds appear as a good tool to discern between irradiated and non-irradiated samples. According to the X-ray diffraction and environmental scanning microscope, the adhered dust in both samples is mainly composed by different amounts of quartz and feldspars. These mineral phases exhibit (i) enough sensitivity to ionizing radiation inducing good Tl intensity, (ii) high stability of the Tl signal during the storage of the material (i.e. low fading) and (iii) are thermally and chemically stable. Blind tests performed under laboratory conditions, but simulating industrial preservation processes (similar temperature and moisture, and presence of white light), allows to distinguish between 1 KGy gamma-irradiated and non-irradiated samples even 11000 hours (15 months) after the irradiation proceeding. (Author)

  10. Thermoluminescence dating of sand dunes at Roonka, South Australia

    International Nuclear Information System (INIS)

    Prescott, J.R.

    1983-01-01

    Thermoluminescence has been used to date sediments associated with the archaeological excavations at Roonka. An age of 65,000 +- 12,000 years has been found for the terra rossa soil immediately underlying the oldest 14 C dated feature at the main site (18,000 years). At the East Bank site, an age of 2700 +- 300 years is found for the top of the dune at a depth of 30 cm. An age of 14,500 +- 2000 years is found for a stratigraphically distinct and sealed layer at a depth of 1 m. A similar (or possibly older) date is found at 1.7 m. These ages are consistent with the archaeological and geomorphological evidence. There is some evidence that bleaching of sediments by daylight may not be complete in the field. If this is confirmed the ages will need to be revised downwards. (author)

  11. Dosimetric of extremities with Dosemeters thermoluminescent in Cuba

    International Nuclear Information System (INIS)

    Molina Perez, D.; Diaz Bernal, E.; Vera Alonso, L.

    1998-01-01

    From final of the year 1995 in the CPHR implement the service of monitoring of the extremities using Dosemeter thermoluminescent (TL). The dosemeter consists on a metallic ring with a circular hole where a detector of LiF:Mg,Ti is placed (model JR1152C) of 5x5x0.9 mm 3 , covered by a fine layer of polyethylene. In the work the characteristic dosimetric as of the dosemeter is studied it satisfies the main requirements for their use in the monitoring from the exhibition to radiation photonic of the extremities. The doses are also presented registered during the first two years of operation of the service. The results obtained until the moment point out to you practice them of nuclear medicine, radiotherapy and production of substances radioactive how as of more contribution

  12. Thermoluminescence dating of Rio Claro and Piracununga formations

    International Nuclear Information System (INIS)

    Ferreira, Sandra Regina; Chang, Maria Rita Caetano

    2008-01-01

    The Rio Claro and Piracununga formations cover extensive areas of the Paulista Peripheral Depression, dominantly in the region of Rio Claro and Piracununga cities. These units lie over the Corumbatai and Piramboia formations, exhibiting discordant contacts. The Rio Claro and Piracununga formations are composed of fine to medium sand facies, showing local cross-stratifications and parallel beddings with thin interbeddings of mud and gravel. These sands were dated by the Thermoluminescence Method, which indicated they were from the Pleistocene age. The oldest age (745,000 years BP) was found in deposits of the Rio Claro Formation; the other ages varied from 400,000 years BP to 145,000 years BP, for both formations. The youngest age (15,000 years BP - close to Pleistocene/ Holocene limit) was found in colluvial deposits, which rest on the Piracununga Formation. (author)

  13. Fluorescence and thermoluminescence in silicon oxide films rich in silicon

    International Nuclear Information System (INIS)

    Berman M, D.; Piters, T. M.; Aceves M, M.; Berriel V, L. R.; Luna L, J. A.

    2009-10-01

    In this work we determined the fluorescence and thermoluminescence (TL) creation spectra of silicon rich oxide films (SRO) with three different silicon excesses. To study the TL of SRO, 550 nm of SRO film were deposited by Low Pressure Chemical Vapor Deposition technique on N-type silicon substrates with resistivity in the order of 3 to 5 Ω-cm with silicon excess controlled by the ratio of the gases used in the process, SRO films with Ro= 10, 20 and 30 (12-6% silicon excess) were obtained. Then, they were thermally treated in N 2 at high temperatures to diffuse and homogenize the silicon excess. In the fluorescence spectra two main emission regions are observed, one around 400 nm and one around 800 nm. TL creation spectra were determined by plotting the integrated TL intensity as function of the excitation wavelength. (Author)

  14. Long-Term Variability of Surface Albedo and Its Correlation with Climatic Variables over Antarctica

    Directory of Open Access Journals (Sweden)

    Minji Seo

    2016-11-01

    Full Text Available The cryosphere is an essential part of the earth system for understanding climate change. Components of the cryosphere, such as ice sheets and sea ice, are generally decreasing over time. However, previous studies have indicated differing trends between the Antarctic and the Arctic. The South Pole also shows internal differences in trends. These phenomena indicate the importance of continuous observation of the Polar Regions. Albedo is a main indicator for analyzing Antarctic climate change and is an important variable with regard to the radiation budget because it can provide positive feedback on polar warming and is related to net radiation and atmospheric heating in the mainly snow- and ice-covered Antarctic. Therefore, in this study, we analyzed long-term temporal and spatial variability of albedo and investigated the interrelationships between albedo and climatic variables over Antarctica. We used broadband surface albedo data from the Satellite Application Facility on Climate Monitoring and data for several climatic variables such as temperature and Antarctic oscillation index (AAO during the period of 1983 to 2009. Time series analysis and correlation analysis were performed through linear regression using albedo and climatic variables. The results of this research indicated that albedo shows two trends, west trend and an east trend, over Antarctica. Most of the western side of Antarctica showed a negative trend of albedo (about −0.0007 to −0.0015 year−1, but the other side showed a positive trend (about 0.0006 year−1. In addition, albedo and surface temperature had a negative correlation, but this relationship was weaker in west Antarctica than in east Antarctica. The correlation between albedo and AAO revealed different relationships in the two regions; west Antarctica had a negative correlation and east Antarctica showed a positive correlation. In addition, the correlation between albedo and AAO was weaker in the west. This

  15. Thermoluminescence glow curves of irradiated PMMA and low density polyethylene

    International Nuclear Information System (INIS)

    Matsuda, Koji; Nakase, Yoshiaki; Kumakiri, Yasuhito; Tsuji, Yoshio.

    1985-03-01

    Light emission from polymers is observed when polymers preirradiated with ionizing radiation at low temperature are heated gradually. The light emission is supposedly resulted from recombination of electrons with active centers produced in polymers or from some other processes involving charge transfer, but no definite explanation has been given at present on the thermoluminescent centers. This report describes our studies on the effects of impurities contained in polymers and pressure of ambient gases on the thermoluminescent glow curve of PMMA and low density polyethylene, which are often used for plastic film dosimeters. In the glow curve of PMMA, only one peak was observed at 110 K in an H 2 or He atmosphere at 760 Torr, but the intensity of the peak decreased with decreasing the H 2 or He gas pressure. At 10 -5 Torr H 2 or He atmosphere the peak disappered, and two sharp peaks appeared in the temperature range from 200 to 250 K. On the other hand, in the glow curve of low density polyethylene, three peaks were observed at 120 K, 180 K and 250 K in the presence of H 2 or He gas at 760 Torr. The effects of pressure of ambient gases and impurities in the polyethylene on these peaks indicate that the peak at 120 K is due to luminescent center produced on the surface or just below the surface of the matrix by collision of excited atoms or molecules of gases with polymer molecules, the peak at 120 K is originated from impurities in the matrix, and the peak at 250 0 K corresponds to luminescent center produced in polyethylene matrix. (author)

  16. Synthesis of CaF2: dy for thermoluminescent dosimetry

    International Nuclear Information System (INIS)

    Yamato, M.E.P.; Vasconcelos, D.A.A. de; Asfora, V.K.; Khoury, H.J.; Santos, R.A.; Barros, V.S.M.

    2015-01-01

    Calcium Fluoride doped with dysprosium is a known thermoluminescent material for applications that require highly sensitive dosimeters. Research in novel methods such as Combustion Synthesis (CS) has been ongoing for several years at the University of Pernambuco. The method uses the heat of the oxi-redox reaction a between nitrate and a fuel. This work presents results of CaF 2 :Dy produced by combustion synthesis under different fabrication conditions. Samples were prepared by mixing stoichiometric amounts of calcium nitrate, urea and ammonium nitrate in a beaker under vigorous stirring. The resulting gel was transferred to a pre-heated muffle furnace were the combustion reaction occurred after a few minutes. For comparison, a variation of the production method with the same amounts of nitrate, ammonium fluoride and dopant, but without using the fuel was prepared. For both methods the resulting powder was pelleted and irradiated with Co-60 gamma radiation. The reproducibility and sensitivity for gamma dose irradiation was tested and results showed that optimum TL sample reproducibility was without the urea as fuel. Samples were then prepared with 0.05, 0.10, 0.15 and 0.20 mol% Dy concentration. The highest TL sensitivity was found for samples with 0.15 mol% Dy and sintered at 400 deg C for 3.5 h in air. The TL emission spectra, obtained using a Hammamatsu optical spectrometer, was comparable with commercial CaF 2 :Dy. Thermoluminescence was measured in a Harshaw-Bicron 3500 TL Reader. The glow curve showed stable dosimetric peaks at around 200, 235 and 300 deg C were a linear dose response curve was obtained for the range 100 mGy to 1000 mGy. (author)

  17. Protocols for Thermoluminescence and Optically Stimulated Luminescence Research at DOSAR

    International Nuclear Information System (INIS)

    Bernal, SM

    2004-01-01

    The Life Sciences Division (LSD) of Oak Ridge National Laboratory (ORNL) has a long record of radiation dosimetry research at the Dosimetry Applications Research (DOSAR) facility complex. These facilities have been used by a broad segment of the research community to perform a variety of experiments in areas including, but not limited to, radiobiology, radiation dosimeter and instrumentation development and calibration, and materials testing in a variety of radiation environments. Collaborations with the University of Tennessee-Knoxville (UTK) have also led to important contributions in the area of archaeometry, particularly as it relates to the use of radiation dosimetry to date archaeological artifacts. This manual is to serve as the primary instruction and operation manual for dosimetric and archaeometric research at DOSAR involving thermoluminescence (TL) and optically stimulated luminescence (OSL). Its purpose is to (1) provide protocols for common practices associated with the research, (2) outline the relevant organizational structure, (3) identify the Quality Assurance plan, and (4) describe all the procedures, operations, and responsibilities for safe and proper operation of associated equipment. Each person who performs research at DOSAR using TL/OSL equipment is required to read the latest revision of this manual and be familiar with its contents, and to sign and date the manual's master copy indicating that the manual has been read and understood. The TL/OSL Experimenter is also required to sign the manual after each revision to signify that the changes are understood. Each individual is responsible for completely understanding the proper operation of the TL/OSL equipment used and for following the guidance contained within this manual. The instructions, protocols, and operating procedures in this manual do not replace, supersede, or alter the hazard mitigation controls identified in the Research Safety Summary (''Thermoluminescence/Optically Stimulated

  18. Positional glow curve simulation for thermoluminescent detector (TLD) system design

    International Nuclear Information System (INIS)

    Branch, C.J.; Kearfott, K.J.

    1999-01-01

    Multi- and thin element dosimeters, variable heating rate schemes, and glow-curve analysis have been employed to improve environmental and personnel dosimetry using thermoluminescent detectors (TLDs). Detailed analysis of the effects of errors and optimization of techniques would be highly desirable. However, an understanding of the relationship between TL light production, light attenuation, and precise heating schemes is made difficult because of experimental challenges involved in measuring positional TL light production and temperature variations as a function of time. This work reports the development of a general-purpose computer code, thermoluminescent detector simulator, TLD-SIM, to simulate the heating of any TLD type using a variety of conventional and experimental heating methods including pulsed focused or unfocused lasers with Gaussian or uniform cross sections, planchet, hot gas, hot finger, optical, infrared, or electrical heating. TLD-SIM has been used to study the impact on the TL light production of varying the input parameters which include: detector composition, heat capacity, heat conductivity, physical size, and density; trapped electron density, the frequency factor of oscillation of electrons in the traps, and trap-conduction band potential energy difference; heating scheme source terms and heat transfer boundary conditions; and TL light scatter and attenuation coefficients. Temperature profiles and glow curves as a function of position time, as well as the corresponding temporally and/or spatially integrated glow values, may be plotted while varying any of the input parameters. Examples illustrating TLD system functions, including glow curve variability, will be presented. The flexible capabilities of TLD-SIM promises to enable improved TLD system design

  19. Preparation of archaeological samples for its dating by thermoluminescence

    International Nuclear Information System (INIS)

    Mejia F, D.

    2000-01-01

    The present work shows the results of the preparation of archaeological samples for their dating by thermoluminescence (Tl) using the Fine grain technique established by Zimmerman but with the varying of such preparation was realized in normal daylight conditions, only the taking of the Tl readings were realized in dark room and red light. In the chapter 1 basic concepts are described about: matter constitution, radioactivity, units and radiation magnitudes, and thermoluminescence. In the chapter 2 some theoretical aspects on dating are showed. It is described how realizing the samples collection, the fine grain method, the determination of the accumulated dose through the years or paleodoses (P=Q+I) by mean of the increasing to obtain the dose equivalent dose (Q) and the signal regeneration method to obtain the correction factor by supra linearity (1), the determination of the annual dose rate to apply the age equation and the evaluation of the age uncertainty with the error limits. The development of experimental part with samples from the archaeological site named Edzna in Campeche, Mexico is described in the chapter 3. The results are presented in the chapter 4. It was obtained an age for the sample named CH7 it was obtained an age of 389 ± years. In conclusion the preparation of the archaeological samples for their dating by Tl in the conditions before mentioned is reliable, but they must be realized more studies with samples of well known age, preparing them in normal daylight conditions and simultaneously in dark room with red light. In order to observe how respond the minerals present in the sample at different dose rapidity, the same samples must be radiated with radiation sources with different dose rate. (Author)

  20. Report on the results of the third intercomparison study of thermoluminescent dosimeters for environmental measurements

    International Nuclear Information System (INIS)

    Driscoll, C.M.H.

    1988-01-01

    Scientific laboratories within the Member States of the European Communities have a continuing interest in the use and development of both thermoluminescent dosimeters and thermoluminescence measurement techniques for the assessment of exposure from environmental gamma radiation. In the United Kingdom, for example, environmental thermoluminescent dosimeters have been developed by the National Radiological Protection Board (NRPB) and used in a national survey of indoor radiation exposure. Other laboratories in various Member States are currently involved in similar studies of natural radiation exposure or are using thermoluminescent dosimeters for environmental measurements at reactor sites. Therefore, it is appropriate that such laboratories have facilities within the European Community for standardization and intercomparison of their environmental measurement techniques

  1. Thermoluminescence properties of micro and nano structure hydroxyapatite after gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shafaei, Mostafa; Ziaie, Farhood; Hajiloo, Nahid [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiation Application Research School

    2016-12-15

    The goal of this study is to compare the thermoluminescence properties of nano and micro structure hydroxyapatite. Nano structure hydroxyapatite was synthesized via hydrolysis method, while the micro structure one was from Merck Company. X-ray diffraction and fourier transform infrared spectroscopy were used to determine the crystal structure and chemical composition of the hydroxyapatite samples. Particles sizes of each sample were estimated using Scherer equation and transmission electron microscopy system. Thermoluminescence properties of the samples were investigated under gamma irradiation. The glow curves of micro and nano structure samples show a peak at 150 C and 200 C, respectively. Thermoluminescence responses of both the samples were linear in the range of 25 - 1 000 Gy where, nano structure sample show a greater slope and stronger linearity in comparison to the micro sample. The results show that the thermoluminescence response of micro sample faded rapidly in comparison to the nano sample due to the existence of the peak at higher temperature.

  2. NRC [Nuclear Regulatory Commission] TLD [thermoluminescent dosimeter] direct radiation monitoring network

    International Nuclear Information System (INIS)

    Struckmeyer, R.; McNamara, N.

    1989-09-01

    This report provides the status and results of the NRC Thermoluminescent Dosimeter (TLD) Direct Radiation Monitoring Network. It presents the radiation levels measured in the vicinity of NRC licensed facility sites throughout the country for the second quarter of 1989

  3. NRC TLD [thermoluminescent dosimeter] Direct Radiation Monitoring Network: Progress report, January-March 1988

    International Nuclear Information System (INIS)

    Struckmeyer, R.; McNamara, N.

    1988-06-01

    This report provides the status and results of the NRC Thermoluminescent Dosimeter (TLD) Direct Radiation Monitoring Network. It presents the radiation levels measured in the vicinity of NRC licensed facility sites throughout the country for the first quarter of 1988

  4. Thermoluminescence in alkali halides irradiated at 80K; Termoluminiscencia en haluros alcalinos irradiados a 80K

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez de Castro, M

    1978-07-01

    The thermoluminescence, the thermally stimulated currents and the thermal stability of the F centres induced in pure NaCl and KC1 crystals by X irradiation at 80K have been studied in detail, In the range between 80 and 300K. The thermoluminescent processes induced by illumination at 80K with F light in samples previously irradiated at room temperature has also been studied. It has been clearly observed the existence of thermoluminescent processes due to electrons and holes thermally released from traps, in which the F centres are not involved. The existence of hole-F centre recombination has not been observed. There are several thermoluminescent processes in both materials which are scribed to the recombination of F centres with mobile interstitial halogen atoms thermally released from traps, which are likely monovalent impurities in this temperature interval. The light emitting stage in these processes is originated by the formation of self trapped excitons. (Author) 66 refs.

  5. Influence of thermoluminescence signal for debris flow surface materials by sunlight bleaching

    International Nuclear Information System (INIS)

    Song Bo; Wei Mingjian; He Youbing; Zhou Rui; Zhao Qiuyue; Zhang Bin

    2013-01-01

    Thermoluminescence was utilized for measuring the thermoluminescence signals of the standard debris flow samples which were bleached by simulated sunlight and debris flow samples after real sunlight bleaching. The experiment results demonstrate that light bleaching phenomenon of the debris flow occurs when it experiences a period of exposure. The thermoluminescence signal of the samples weakens gradually with the increase of depth. The optical bleaching phenomenon is obvious. Within a certain depth, light bleaching phenomenon is enhanced with the increase of light intensity. The annealing depth of simulated sunlight bleaching experiment is about 1 mm, and the actual annealing depth of sunlight bleaching is about 6 mm. According to the equivalent dose variation with depth, the mud of natural debris flow can be divided into two stages. It has fundamental significance in the application of thermoluminescence dating techniques to divide the stages of debris flow sediments. (authors)

  6. Analysis of the thermoluminescent signal in the hydroxyapatite synthesized by the sol-gel method

    International Nuclear Information System (INIS)

    Mendoza A, D.; Gonzalez, P.R.; Lobato, M.; Rubio, E.; Rodriguez L, V.; Custodio, E.

    2004-01-01

    The physical properties of the ceramics are related with the chemical bonds and the crystalline structure, because the elements that constitute it can be united by ionic bonds or partially ionic giving a covalent character, this last causes that the outer layer is full of electrons. This property makes that the ceramic ones become interesting materials for thermoluminescent applications, as it demonstrates through the recent works presented on the hydroxyapatite that is a ceramic biomaterials that has shown an interesting thermoluminescent signal when being exposed to gamma radiation. In this sense, this work presents the thermoluminescent signal analysis induced by the UV and gamma radiation in a particular type of hydroxyapatite synthesized by sol gel method in which the temperature synthesis is varied. The final thermoluminescent sensitivity of materials is correlated with the crystalline degree, which is analysed through X-ray diffraction. (Author)

  7. Measurement conditions of natural soil thermoluminescence and their application in a granite type uranium deposit

    International Nuclear Information System (INIS)

    Chen Yue; Yang Yaxin; Liu Qingcheng

    2009-01-01

    A measuring method of natural soil thermoluminescence is used for prospecting of uranium deposits. The better effects are obtained by using the method, but the parameters selected have significant effects on the intensity of soil thermoluminescent. So, the measuring parameters are selected according to the different soil samples. Based on the measuring 1 000 soil samples of granite type uranium deposit,the optimum heating up program of natural soil thermoluminescence is obtained, that is, preheating, lasting heating, constant temperature and the halting heating. The parameters selected are as follows: the heating rate being 15 degree C/s, the temperatures of the first and second constant temperature being 135 degree C and 400 degree C respectively. Using the selected parameters for measuring soil samples from a known mining area in Guangdong province, the result indicates that the abnormities of thermoluminescence have corresponding relations with the underground orebodies. (authors)

  8. Thermoluminescence study of quartzite in a gold and uranium mineralized zone (Canavieiras, Jacobina-Bahia)

    International Nuclear Information System (INIS)

    Ferreira, J.

    1973-01-01

    The quartzite of Canavieiras gold mine (Jacobina-Bahia, Brazil) shows in its natural glow curve, a high temperature. The study of the reproductibility of this peak resulted in the standartization of measurement for grain sizes between 80 and 100 mesh. ''In Situ'' total gamma-ray profiles were made using a scintillation detector for the study the distribution of radioactive elements near the pirite, uranium and gold strike. In the interpretation of the profiles it was possible to shown a positive correlation between thermoluminescence and uranium yields. The thermoluminescence peak is sufficiently high temperature peak to let thermoluminescence accumulate at ambient temperatures. It was used in attempt to estimate the time and the event that enitiated the accumulation of thermoluminescence. The result obtained, (7 - + 4).10 6 years, may correspond to the last heating of the rocks at relatively recent time. (C.D.G.) [pt

  9. Study of natural thermoluminescence of quartzite in a gold and uranium mineralized zone (Canavieiras, Jacobina, Brazil)

    International Nuclear Information System (INIS)

    Ferreira, J.; Nordemann, D.

    1976-01-01

    The quartzite of the Canavieiras gold mine (Jacobina, Bahia, Brazil) exhibits a high temperature peak (280 +- 2) 0 C in its natural thermoluminescence glow curve. It was experimentally determined that the amount of light in this peak could be reproduced to within 5% for grain sizes between 80 and 100 mesh (0.149 and 0.177 mm). A positive correlation was found between the amount of this thermoluminescence and the uranium content with saturation beginning to be detected at the maximum (700 ppm) amount of uranium found. Assuming that the thermoluminescence peak used is at a temperature high enough to permit accumulation and stability at room temperatures, the thermoluminescence found could have accumulated in (12.1 +- 0.3) x 10 6 years. This may date a complete liberation of trapped electrons in conjunction with a well documented initiation of weathering. (author) [pt

  10. Exposure levels to radiation in a nuclear medicine laboratory: measurements with thermoluminescence dosemeters

    International Nuclear Information System (INIS)

    Ruiz J, A.

    2000-01-01

    Since 1996 in the Nuclear medicine Department and another routine and research departments of the National Institute of Medical and Nutrition Sciences (INCMNSZ) are working at least with 12 radioactive sources opened and sealed. However, it was unknown if with the Tl personal dosemeters with lithium fluoride crystals (LiF), could be possible to receive information about the equivalent dose for each radionuclide or if there was some radionuclide that by being low energy emissor or beta energy emissor, it did not represent an ionization power sufficient to excite the crystals of the thermoluminescent dosemeters (DTL). In this work the obtained results with control dosemeters of diverse source opened or sealed are shown, which were put at 1 cm of the LiF crystals during a time exposure 18 hours. Therefore the objective of this work is to verify which sources excite or not to DTL crystals and taking the pertinent safety measures for each radionuclide. The conclusion is that the majority of dosemeters were excited by beta or gamma radiation of the radionuclides and that LiF crystals are able to receive equivalent doses until 1200 mSv, being this a guarantee for the staff, that in an any moment could be exposed to high dose in his working day. Also it was corroborated that the radionuclides more energizer are: iodine-131, iodine-125 and sodium-22 while the phosphorus-32 must be managed with careful, since the exposure to hands can result significant, just like the technetium-99m ( 99m Tc). (Author)

  11. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains Central Facility

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, Sally A.; Gaustad, Krista L.; Mlawer, Eli J.; Long, Charles N.; Delamere, Jennifer

    2011-09-01

    We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  12. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

    Science.gov (United States)

    McFarlane, S. A.; Gaustad, K. L.; Mlawer, E. J.; Long, C. N.; Delamere, J.

    2011-09-01

    We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  13. Routine Radiological Environmental Monitoring Plan

    International Nuclear Information System (INIS)

    Bechtel Nevada

    1998-01-01

    The U.S. Department of Energy manages the Nevada Test Site in a manner that meets evolving DOE Missions and responds to the concerns of affected and interested individuals and agencies. This Routine Radiological Monitoring Plan addressess complicance with DOE Orders 5400.1 and 5400.5 and other drivers requiring routine effluent monitoring and environmental surveillance on the Nevada Test Site. This monitoring plan, prepared in 1998, addresses the activities conducted onsite NTS under the Final Environmental Impact Statement and Record of Decision. This radiological monitoring plan, prepared on behalf of the Nevada Test Site Landlord, brings together sitewide environmental surveillance; site-specific effluent monitoring; and operational monitoring conducted by various missions, programs, and projects on the NTS. The plan provides an approach to identifying and conducting routine radiological monitoring at the NTS, based on integrated technical, scientific, and regulatory complicance data needs

  14. Using Remote Sensing to Quantify Roof Albedo in Seven California Cities

    Science.gov (United States)

    Ban-Weiss, G. A.; Woods, J.; Millstein, D.; Levinson, R.

    2013-12-01

    Cool roofs reflect sunlight and therefore can reduce cooling energy use in buildings. Further, since roofs cover about 20-25% of cities, wide spread deployment of cool roofs could mitigate the urban heat island effect and partially counter urban temperature increases associated with global climate change. Accurately predicting the potential for increasing urban albedo using reflective roofs and its associated energy use and climate benefits requires detailed knowledge of the current stock of roofs at the city scale. Until now this knowledge has been limited due to a lack of availability of albedo data with sufficient spatial coverage, spatial resolution, and spectral information. In this work we use a novel source of multiband aerial imagery to derive the albedos of individual roofs in seven California cities: Los Angeles, Long Beach, San Diego, Bakersfield, Sacramento, San Francisco, and San Jose. The radiometrically calibrated, remotely sensed imagery has high spatial resolution (1 m) and four narrow (less than 0.1 μm wide) band reflectances: blue, green, red, and near-infrared. To derive the albedo of roofs in each city, we first locate roof pixels within GIS building outlines. Next we use laboratory measurements of the solar spectral reflectances of 190 roofing products to empirically relate solar reflectance (albedo) to reflectances in the four narrow bands; the root-mean-square of the residuals for the albedo prediction is 0.016. Albedos computed from remotely sensed reflectances are calibrated to ground measurements of roof albedo in each city. The error (both precision and accuracy) of albedo values is presented for each city. The area-weighted mean roof albedo (× standard deviation) for each city ranges from 0.17 × 0.08 (Los Angeles) to 0.29 × 0.15 (San Diego). In each city most roofs have low albedo in the range of 0.1 to 0.3. Roofs with albedo greater than 0.4 comprise less than 3% of total roofs and 7% of total roof area in each city. The California

  15. Near-ground cooling efficacies of trees and high-albedo surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Levinson, Ronnen M. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering

    1997-05-01

    Daytime summer urban heat islands arise when the prevalence of dark-colored surfaces and lack of vegetation make a city warmer than neighboring countryside. Two frequently-proposed summer heat island mitigation measures are to plant trees and to increase the albedo (solar reflectivity) of ground surfaces. This dissertation examines the effects of these measures on the surface temperature of an object near the ground, and on solar heating of air near the ground. Near-ground objects include people, vehicles, and buildings. The variation of the surface temperature of a near-ground object with ground albedo indicates that a rise in ground albedo will cool a near-ground object only if the object`s albedo exceeds a critical value. This critical value of object albedo depends on wind speed, object geometry, and the height of the atmospheric thermal boundary layer. It ranges from 0.15 to 0.37 for a person. If an object has typical albedo of 0.3, increasing the ground albedo by.

  16. Mapping Surface Broadband Albedo from Satellite Observations: A Review of Literatures on Algorithms and Products

    Directory of Open Access Journals (Sweden)

    Ying Qu

    2015-01-01

    Full Text Available Surface albedo is one of the key controlling geophysical parameters in the surface energy budget studies, and its temporal and spatial variation is closely related to the global climate change and regional weather system due to the albedo feedback mechanism. As an efficient tool for monitoring the surfaces of the Earth, remote sensing is widely used for deriving long-term surface broadband albedo with various geostationary and polar-orbit satellite platforms in recent decades. Moreover, the algorithms for estimating surface broadband albedo from satellite observations, including narrow-to-broadband conversions, bidirectional reflectance distribution function (BRDF angular modeling, direct-estimation algorithm and the algorithms for estimating albedo from geostationary satellite data, are developed and improved. In this paper, we present a comprehensive literature review on algorithms and products for mapping surface broadband albedo with satellite observations and provide a discussion of different algorithms and products in a historical perspective based on citation analysis of the published literature. This paper shows that the observation technologies and accuracy requirement of applications are important, and long-term, global fully-covered (including land, ocean, and sea-ice surfaces, gap-free, surface broadband albedo products with higher spatial and temporal resolution are required for climate change, surface energy budget, and hydrological studies.

  17. Analysis of earth albedo effect on sun sensor measurements based on theoretical model and mission experience

    Science.gov (United States)

    Brasoveanu, Dan; Sedlak, Joseph

    1998-01-01

    Analysis of flight data from previous missions indicates that anomalous Sun sensor readings could be caused by Earth albedo interference. A previous Sun sensor study presented a detailed mathematical model of this effect. The model can be used to study the effect of both diffusive and specular reflections and to improve Sun angle determination based on perturbed Sun sensor measurements, satellite position, and an approximate knowledge of attitude. The model predicts that diffuse reflected light can cause errors of up to 10 degrees in Coarse Sun Sensor (CSS) measurements and 5 to 10 arc sec in Fine Sun Sensor (FSS) measurements, depending on spacecraft orbit and attitude. The accuracy of these sensors is affected as long as part of the illuminated Earth surface is present in the sensor field of view. Digital Sun Sensors (DSS) respond in a different manner to the Earth albedo interference. Most of the time DSS measurements are not affected, but for brief periods of time the Earth albedo can cause errors which are a multiple of the sensor least significant bit and may exceed one degree. This paper compares model predictions with Tropical Rainfall Measuring Mission (TRMM) CSS measurements in order to validate and refine the model. Methods of reducing and mitigating the impact of Earth albedo are discussed. ne CSS sensor errors are roughly proportional to the Earth albedo coefficient. Photocells that are sensitive only to ultraviolet emissions would reduce the effective Earth albedo by up to a thousand times, virtually eliminating all errors caused by Earth albedo interference.

  18. Surface albedo in different land-use and cover types in Amazon forest region

    Directory of Open Access Journals (Sweden)

    Thiago de Oliveira Faria

    2018-05-01

    Full Text Available Albedo is the portion of energy from the Sun that is reflected by the earth's surface, thus being an important variable that controls climate and energy processes on Earth. Surface albedo is directly related to the characteristics of the Earth’s surface materials, making it a useful parameter to evaluate the effects of original soil cover replacement due to human occupation. This study evaluated the changes in the surface albedo values due to the conversion of vegetation to other land uses and to analyze the applicability of the use of albedo in the spatial delimitation of land-use classes in the transitional region between the Cerrado and Amazon biomes. Surface albedo measurements were obtained from processing of Landsat Thematic Mapper data in the Geographic Information System (GIS, and land-use information were collected using Google Earth high-resolution images. The results show that human activities such as the cultivation of crops and burning have contributed substantially to variations in the surface albedo, and that albedo estimates from Landsat imagery have the potential to help in the recognition and delimitation of features of land use and cover.

  19. A Method for Retrieving Daily Land Surface Albedo from Space at 30-m Resolution

    Directory of Open Access Journals (Sweden)

    Bo Gao

    2015-08-01

    Full Text Available Land surface albedo data with high spatio-temporal resolution are increasingly important for scientific studies addressing spatially and/or temporally small-scale phenomena, such as urban heat islands and urban land surface energy balance. Our previous study derived albedo data with 2–4-day and 30-m temporal and spatial resolution that have better spatio-temporal resolution than existing albedo data, but do not completely satisfy the requirements for monitoring high-frequency land surface changes at the small scale. Downscaling technology provides a chance to further improve the albedo data spatio-temporal resolution and accuracy. This paper introduces a method that combines downscaling technology for land surface reflectance with an empirical method of deriving land surface albedo. Firstly, downscaling daily MODIS land surface reflectance data (MOD09GA from 500 m to 30 m on the basis of HJ-1A/B BRDF data with 2–4-day and 30-m temporal and spatial resolution is performed: this is the key step in the improved method. Subsequently, the daily 30-m land surface albedo data are derived by an empirical method combining prior knowledge of the MODIS BRDF product and the downscaled daily 30-m reflectance. Validation of albedo data obtained using the proposed method shows that the new method has both improved spatio-temporal resolution and good accuracy (a total absolute accuracy of 0.022 and a total root mean squared error at six sites of 0.028.

  20. The institutionalization of a routine

    DEFF Research Database (Denmark)

    Nickelsen, Niels Christian

    2008-01-01

    -which has before largely been treated in overview by institutionalism-plays an important role in the making of a routine. In my empirical study, I demonstrate that the concept and practice of the valve changes, and that it is identified in a number of ways, as it passes through the testing phase...... of production. I argue that the negotiation of these changes during test production is the fulcrum in the routinization of the production procedure. It is through these identity shifts that the valve is both reified, and rendered producible and applicable in the customer world....

  1. Climate implications of including albedo effects in terrestrial carbon policy

    Science.gov (United States)

    Jones, A. D.; Collins, W.; Torn, M. S.; Calvin, K. V.

    2012-12-01

    Proposed strategies for managing terrestrial carbon in order to mitigate anthropogenic climate change, such as financial incentives for afforestation, soil carbon sequestration, or biofuel production, largely ignore the direct effects of land use change on climate via biophysical processes that alter surface energy and water budgets. Subsequent influences on temperature, hydrology, and atmospheric circulation at regional and global scales could potentially help or hinder climate stabilization efforts. Because these policies often rely on payments or credits expressed in units of CO2-equivalents, accounting for biophysical effects would require a metric for comparing the strength of biophysical climate perturbation from land use change to that of emitting CO2. One such candidate metric that has been suggested in the literature on land use impacts is radiative forcing, which underlies the global warming potential metric used to compare the climate effects of various greenhouse gases with one another. Expressing land use change in units of radiative forcing is possible because albedo change results in a net top-of-atmosphere radiative flux change. However, this approach has also been critiqued on theoretical grounds because not all climatic changes associated with land use change are principally radiative in nature, e.g. changes in hydrology or the vertical distribution of heat within the atmosphere, and because the spatial scale of land use change forcing differs from that of well-mixed greenhouse gases. To explore the potential magnitude of this discrepancy in the context of plausible scenarios of future land use change, we conduct three simulations with the Community Climate System Model 4 (CCSM4) utilizing a slab ocean model. Each simulation examines the effect of a stepwise change in forcing relative to a pre-industrial control simulation: 1) widespread conversion of forest land to crops resulting in approximately 1 W/m2 global-mean radiative forcing from albedo

  2. Improvement of Mars surface snow albedo modeling in LMD Mars GCM with SNICAR

    Science.gov (United States)

    Singh, D.; Flanner, M.; Millour, E.

    2017-12-01

    The current version of Laboratoire de Météorologie Dynamique (LMD) Mars GCM (original-MGCM) uses annually repeating (prescribed) albedo values from the Thermal Emission Spectrometer observations. We integrate the Snow, Ice, and Aerosol Radiation (SNICAR) model with MGCM (SNICAR-MGCM) to prognostically determine H2O and CO2 ice cap albedos interactively in the model. Over snow-covered regions mean SNICAR-MGCM albedo is higher by about 0.034 than original-MGCM. Changes in albedo and surface dust content also impact the shortwave energy flux at the surface. SNICAR-MGCM model simulates a change of -1.26 W/m2 shortwave flux on a global scale. Globally, net CO2 ice deposition increases by about 4% over one Martian annual cycle as compared to original-MGCM simulations. SNICAR integration reduces the net mean global surface temperature, and the global surface pressure of Mars by about 0.87% and 2.5% respectively. Changes in albedo also show a similar distribution as dust deposition over the globe. The SNICAR-MGCM model generates albedos with higher sensitivity to surface dust content as compared to original-MGCM. For snow-covered regions, we improve the correlation between albedo and optical depth of dust from -0.91 to -0.97 with SNICAR-MGCM as compared to original-MGCM. Using new diagnostic capabilities with this model, we find that cryospheric surfaces (with dust) increase the global surface albedo of Mars by 0.022. The cryospheric effect is severely muted by dust in snow, however, which acts to decrease the planet-mean surface albedo by 0.06.

  3. Impacts of Synoptic Weather Patterns on Snow Albedo at Sites in New England

    Science.gov (United States)

    Adolph, A. C.; Albert, M. R.; Lazarcik, J.; Dibb, J. E.; Amante, J.; Price, A. N.

    2015-12-01

    Winter snow in the northeastern United States has changed over the last several decades, resulting in shallower snow packs, fewer days of snow cover and increasing precipitation falling as rain in the winter. In addition to these changes which cause reductions in surface albedo, increasing winter temperatures also lead to more rapid snow grain growth, resulting in decreased snow reflectivity. We present in-situ measurements and analyses to test the sensitivity of seasonal snow albedo to varying weather conditions at sites in New England. In particular, we investigate the impact of temperature on snow albedo through melt and grain growth, the impact of precipitation event frequency on albedo through snow "freshening," and the impact of storm path on snow structure and snow albedo. Over three winter seasons between 2013 and 2015, in-situ snow characterization measurements were made at three non-forested sites across New Hampshire. These near-daily measurements include spectrally resolved albedo, snow optical grain size determined through contact spectroscopy, snow depth, snow density and local meteorological parameters. Combining this information with storm tracks derived from HYSPLIT modeling, we quantify the current sensitivity of northeastern US snow albedo to temperature as well as precipitation type, frequency and path. Our analysis shows that southerly winter storms result in snow with a significantly lower albedo than storms which come from across the continental US or the Atlantic Ocean. Interannual variability in temperature and statewide spatial variability in snowfall rates at our sites show the relative importance of snowfall amount and temperatures in albedo evolution over the course of the winter.

  4. Albedo enhancement over land to counteract global warming: impacts on hydrological cycle

    Energy Technology Data Exchange (ETDEWEB)

    Bala, Govindasamy; Nag, Bappaditya [Indian Institute of Science, Divecha Center for Climate Change and Center for Atmospheric and Oceanic Sciences, Bangalore (India)

    2012-09-15

    A recent modelling study has shown that precipitation and runoff over land would increase when the reflectivity of marine clouds is increased to counter global warming. This implies that large scale albedo enhancement over land could lead to a decrease in runoff over land. In this study, we perform simulations using NCAR CAM3.1 that have implications for Solar Radiation Management geoengineering schemes that increase the albedo over land. We find that an increase in reflectivity over land that mitigates the global mean warming from a doubling of CO{sub 2} leads to a large residual warming in the southern hemisphere and cooling in the northern hemisphere since most of the land is located in northern hemisphere. Precipitation and runoff over land decrease by 13.4 and 22.3%, respectively, because of a large residual sinking motion over land triggered by albedo enhancement over land. Soil water content also declines when albedo over land is enhanced. The simulated magnitude of hydrological changes over land are much larger when compared to changes over oceans in the recent marine cloud albedo enhancement study since the radiative forcing over land needed (-8.2 W m{sup -2}) to counter global mean radiative forcing from a doubling of CO{sub 2} (3.3 W m{sup -2}) is approximately twice the forcing needed over the oceans (-4.2 W m{sup -2}). Our results imply that albedo enhancement over oceans produce climates closer to the unperturbed climate state than do albedo changes on land when the consequences on land hydrology are considered. Our study also has important implications for any intentional or unintentional large scale changes in land surface albedo such as deforestation/afforestation/reforestation, air pollution, and desert and urban albedo modification. (orig.)

  5. Deriving albedo maps for HAPEX-Sahel from ASAS data using kernel-driven BRDF models

    Directory of Open Access Journals (Sweden)

    P. Lewis

    1999-01-01

    Full Text Available This paper describes the application and testing of a method for deriving spatial estimates of albedo from multi-angle remote sensing data. Linear kernel-driven models of surface bi-directional reflectance have been inverted against high spatial resolution multi-angular, multi- spectral airborne data of the principal cover types within the HAPEX-Sahel study site in Niger, West Africa. The airborne data are obtained from the NASA Airborne Solid-state Imaging Spectrometer (ASAS instrument, flown in Niger in September and October 1992. The maps of model parameters produced are used to estimate integrated reflectance properties related to spectral albedo. Broadband albedo has been estimated from this by weighting the spectral albedo for each pixel within the map as a function of the appropriate spectral solar irradiance and proportion of direct and diffuse illumination. Partial validation of the results was performed by comparing ASAS reflectance and derived directional-hemispherical reflectance with simulations of a millet canopy made with a complex geometric canopy reflectance model, the Botanical Plant Modelling System (BPMS. Both were found to agree well in magnitude. Broadband albedo values derived from the ASAS data were compared with ground-based (point sample albedo measurements and found to agree extremely well. These results indicate that the linear kernel-driven modelling approach, which is to be used operationally to produce global 16 day, 1 km albedo maps from forthcoming NASA Earth Observing System spaceborne data, is both sound and practical for the estimation of angle-integrated spectral reflectance quantities related to albedo. Results for broadband albedo are dependent on spectral sampling and on obtaining the correct spectral weigthings.

  6. Migration of Frosts from High-Albedo Regions of Pluto: what New Horizons Reveals

    Science.gov (United States)

    Buratti, Bonnie J.; Stern, S. A.; Weaver, Hal A.; Young, Leslie A.; Olkin, Cathy B.; Ennico, Kimberly; Binzel, Richard P.; Zangari, Amanda; Earle, Alissa M.

    2015-11-01

    With its high eccentricity and obliquity, Pluto should exhibit seasonal volatile transport on its surface. Several lines of evidence support this transport: doubling of Pluto’s atmospheric pressure over the past two decades (Young et al., 2013, Ap. J. 766, L22; Olkin et al., 2015, Icarus 246, 230); changes in its historical rotational light curve, once all variations due to viewing geometry have been modelled (Buratti et al., 2015; Ap. J. 804, L6); and changes in HST albedo maps (Buie et al., 2010, Astron. J. 139, 1128). New Horizons LORRI images reveal that the region of greatest albedo change is not the polar cap(s) of Pluto, but the feature informally named Tombaugh Regio (TR). This feature has a normal reflectance as high as ~0.8 in some places, and it is superposed on older, lower-albedo pre-existing terrain with an albedo of only ~0.10. This contrast is larger than any other body in the Solar System, except for Iapetus. This albedo dichotomy leads to a complicated system of cold-trapping and thermal segregation, beyond the simple picture of seasonal volatile transport. Whatever the origin of TR, it initially acted as a cold trap, as the temperature differential between the high and low albedo regions could be enormous, possibly approaching 20K, based on their albedo differences and assuming their normalized phase curves are similar. This latter assumption will be refined as the full New Horizons data set is returned.Over six decades of ground-based photometry suggest that TR has been decreasing in albedo over the last 25 years. Possible causes include changing insolation angles, or sublimation from the edges where the high-albedo material impinges on a much warmer substrate.Funding by the NASA New Horizons Project acknowledged.

  7. Assessment of Satellite Albedos Using NASA-CAR Airborne Data

    Science.gov (United States)

    Kharbouche, S.; Charles, G.; Muller, J. P.

    2016-12-01

    Airborne BRF (Bidirectional Reflectance Factor) data has been acquired at multiple altitudes by the NASA CAR (Cloud Absorption Radiometer) multi-spectral instrument since the late 1990s in order to study the reflectance over different types of landscapes depending upon wavelengths, view angles and spatial scales, and to assess derived BRFs from multispectral satellites. As the measured BRFs are taken over a very short period (BRDF for different sites in the Arctic. Also, as the measurements have been taken at different flight heights, the upscaling issue can be addressed and detailed with concrete samples. The CAR instrument is well calibrated (back to NIST standards) and can be compared with some ground measurements on the ground. So the derived BRF data for this instrument are likely to be highly reliable and can be used in the validation of some satellites products like radiance, reflectance and albedo, as well as in the BRDF (Bidirectional Reflectance Distribution Function) modelling and in the development of new atmospheric correction techniques. The NASA-CAR, developed by NASA-GSFC can be carried and integrated into many experimental aircraft. So, CAR can be considered as an airborne multi-wavelength scanning radiometer that can measure radiance with instantaneous fields of view of 1°. Over targeted sites, the CAR flies circularly and scans through 180° from straight above, through the horizon to straight down. Data are recorded in 14 narrow spectral bands located in the ultraviolet, visible and near-infrared regions in the electromagnetic spectrum (0.340-2.301 mm). The ray or spot at nadir depends on the flight height. It varies from 1m (height=110m) to 48m (height=5500m). We will show in this presentation the accuracy of BRF, BRDF and Black-Sky-Albedo of MODIS, MISR, MERIS, VGT, Landsat-7 and AVHRR, over vegetated, non-vegetated and ice-covered sites. We will show also how CAR data are arranged and how can be read and deployed. This work was supported by

  8. Three-group albedo method applied to the diffusion phenomenon with up-scattering of neutrons

    International Nuclear Information System (INIS)

    Terra, Andre M. Barge Pontes Torres; Silva, Jorge A. Valle da; Cabral, Ronaldo G.

    2007-01-01

    The main objective of this research is to develop a three-group neutron Albedo algorithm considering the up-scattering of neutrons in order to analyse the diffusion phenomenon in nonmultiplying media. The neutron Albedo method is an analytical method that does not try to solve describing explicit equations for the neutron fluxes. Thus the neutron Albedo methodology is very different from the conventional methodology, as the neutron diffusion theory model. Graphite is analyzed as a model case. One major application is in the determination of the nonleakage probabilities with more understandable results in physical terms than conventional radiation transport method calculations. (author)

  9. A MATHEMATICAL APPROACH TO ECONOMY OF EXPERIMENT IN DETERMINATIONS OF THE DIFFERENTIAL DOSE ALBEDO OF GAMMA RAYS

    Energy Technology Data Exchange (ETDEWEB)

    Shoemaker, N. F.; Huddleston, C. M.

    1962-12-10

    Treatments of the differential dose albedo of gamma rays on concrete have supposed that the albedo value is a function of: the energy of the incident gamma radiation, the polar angle of incidence, the polar angle of reflection (or scatter), and the azimuthal angle of reflection. It is demonstrated that, if certain reasonable assumptions are made regarding the mechanism of reflection, it is not necessary to investigate variations in albedo with azimuthal angle of refiection. Once differential dose albedo has been determined for a complete set of incident and reflected polar angles with zero azimuth, albedo at any azimuth can be derived by a suitable transformation. (auth)

  10. Microfoundations of Routines and Capabilities

    DEFF Research Database (Denmark)

    Felin, Tippo; Foss, Nicolai Juul; Heimericks, Koen H.

    2012-01-01

    This article introduces the Special Issue and discusses the microfoundations of routines and capabilities, including why a microfoundations view is needed and how it may inform work on organizational and competitive heterogeneity. Building on extant research, we identify three primary categories ...

  11. Thermoluminescence properties of graphene–nano ZnS composite

    International Nuclear Information System (INIS)

    Sharma, Geeta; Gosavi, S.W.

    2014-01-01

    This work describes the thermoluminescence (TL) of graphene oxide (GO), reduced graphene oxide (RGO) and graphene–nano ZnS composite. Graphene oxide was synthesized using Hummer's method and then reduced to graphene by hydrazine hydrate. G–ZnS was synthesized via in-situ reduction of graphene oxide (GO) and zinc nitrate [Zn(NO 3 ) 2 ] by sodium sulfide (Na 2 S). The structures of samples were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). XRD pattern confirmed the formation of graphene oxide, reduced graphene oxide and G–ZnS lattice. The p-XRD spectrum of G–ZnS shows peaks of ZnS superimposed on those of graphene and the particle size of ZnS in the complex is less than 10 nm. Ultra thin graphene and graphene oxide sheets with size ranging between tens to several hundreds of square nanometers are observed in TEM images. The TEM micrographs of G–ZnS show that ZnS particles are embedded in graphene sheets and the average particle size of ZnS particles in the composite is less than 10 nm. Samples of RGO, GO and G–ZnS were exposed to different doses of γ-rays in the range of 1 Gy to 50 kGy. The reduced graphene oxide (RGO) did not show any thermoluminescence emission. The thermoluminescence glow curve of GO has a single broad peak whose peak position varied between 500 and 550 K with an absorbed dose increasing from 1 Gy to 5000 Gy. GO shows most intense TL peak, positioned at 523.6 K for a dose of 10 kGy. The glow curves of G–ZnS over the entire range of irradiation have single peak positioned between 492 and 527 K with variation in dose from 1 Gy to 50 kGy. G–ZnS shows the most intense TL glow curve for a dose of 50 kGy. The TL response curve of G–ZnS is found to be linear over a larger dose range from 1 Gy to 50 kGy whereas the response curve of GO shows linearity only at low doses up to 100 Gy. -- Highlights: • Graphene oxide, reduced graphene oxide and graphene–nano ZnS were synthesized. • TL of

  12. Constraining the instantaneous aerosol influence on cloud albedo

    Energy Technology Data Exchange (ETDEWEB)

    Gryspeerdt, Edward; Quaas, Johannes; Ferrachat, Sylvaine; Gettelman, Andrew; Ghan, Steven; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G.; Stier, Philip; Takemura, Toshihiko; Wang, Hailong; Wang, Minghuai; Zhang, Kai

    2017-04-26

    Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol–cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration (Nd), previous studies have used the sensitivity of the Nd to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol and cloud properties in the present-day climate may not be suitable for determining the sensitivity of the Nd to anthropogenic aerosol perturbations. Using an ensemble of global aerosol–climate models, this study demonstrates how joint histograms between Nd and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. The accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol–cloud interactions in satellite data.

  13. NEOWISE Reactivation Mission Year Three: Asteroid Diameters and Albedos

    Energy Technology Data Exchange (ETDEWEB)

    Masiero, Joseph R.; Mainzer, A. K.; Kramer, E. [Jet Propulsion Laboratory/California Institute of Technology, 4800 Oak Grove Drive, MS 183-301, Pasadena, CA 91109 (United States); Nugent, C.; Cutri, R. M. [California Institute of Technology, Infrared Processing and Analysis Center, 1200 California Boulevard, Pasadena, CA 91125 (United States); Wright, E. L. [University of California, Los Angeles, CA 90095 (United States); Bauer, J. M. [University of Maryland, College Park, MD 20742 (United States); Grav, T.; Sonnett, S., E-mail: Joseph.Masiero@jpl.nasa.gov [Planetary Science Institute, 1700 E Fort Lowell Road #106, Tucson, AZ 85719 (United States)

    2017-10-01

    The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) reactivation mission has completed its third year of surveying the sky in the thermal infrared for near-Earth asteroids and comets. NEOWISE collects simultaneous observations at 3.4 and 4.6  μ m of solar system objects passing through its field of regard. These data allow for the determination of total thermal emission from bodies in the inner solar system, and thus the sizes of these objects. In this paper, we present thermal model fits of asteroid diameters for 170 NEOs and 6110 Main Belt asteroids (MBAs) detected during the third year of the survey, as well as the associated optical geometric albedos. We compare our results with previous thermal model results from NEOWISE for overlapping sample sets, as well as diameters determined through other independent methods, and find that our diameter measurements for NEOs agree to within 26% (1 σ ) of previously measured values. Diameters for the MBAs are within 17% (1 σ ). This brings the total number of unique near-Earth objects characterized by the NEOWISE survey to 541, surpassing the number observed during the fully cryogenic mission in 2010.

  14. NEOWISE Reactivation Mission Year Three: Asteroid Diameters and Albedos

    International Nuclear Information System (INIS)

    Masiero, Joseph R.; Mainzer, A. K.; Kramer, E.; Nugent, C.; Cutri, R. M.; Wright, E. L.; Bauer, J. M.; Grav, T.; Sonnett, S.

    2017-01-01

    The Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) reactivation mission has completed its third year of surveying the sky in the thermal infrared for near-Earth asteroids and comets. NEOWISE collects simultaneous observations at 3.4 and 4.6  μ m of solar system objects passing through its field of regard. These data allow for the determination of total thermal emission from bodies in the inner solar system, and thus the sizes of these objects. In this paper, we present thermal model fits of asteroid diameters for 170 NEOs and 6110 Main Belt asteroids (MBAs) detected during the third year of the survey, as well as the associated optical geometric albedos. We compare our results with previous thermal model results from NEOWISE for overlapping sample sets, as well as diameters determined through other independent methods, and find that our diameter measurements for NEOs agree to within 26% (1 σ ) of previously measured values. Diameters for the MBAs are within 17% (1 σ ). This brings the total number of unique near-Earth objects characterized by the NEOWISE survey to 541, surpassing the number observed during the fully cryogenic mission in 2010.

  15. Constraining the instantaneous aerosol influence on cloud albedo.

    Science.gov (United States)

    Gryspeerdt, Edward; Quaas, Johannes; Ferrachat, Sylvaine; Gettelman, Andrew; Ghan, Steven; Lohmann, Ulrike; Morrison, Hugh; Neubauer, David; Partridge, Daniel G; Stier, Philip; Takemura, Toshihiko; Wang, Hailong; Wang, Minghuai; Zhang, Kai

    2017-05-09

    Much of the uncertainty in estimates of the anthropogenic forcing of climate change comes from uncertainties in the instantaneous effect of aerosols on cloud albedo, known as the Twomey effect or the radiative forcing from aerosol-cloud interactions (RFaci), a component of the total or effective radiative forcing. Because aerosols serving as cloud condensation nuclei can have a strong influence on the cloud droplet number concentration ( N d ), previous studies have used the sensitivity of the N d to aerosol properties as a constraint on the strength of the RFaci. However, recent studies have suggested that relationships between aerosol and cloud properties in the present-day climate may not be suitable for determining the sensitivity of the N d to anthropogenic aerosol perturbations. Using an ensemble of global aerosol-climate models, this study demonstrates how joint histograms between N d and aerosol properties can account for many of the issues raised by previous studies. It shows that if the anthropogenic contribution to the aerosol is known, the RFaci can be diagnosed to within 20% of its actual value. The accuracy of different aerosol proxies for diagnosing the RFaci is investigated, confirming that using the aerosol optical depth significantly underestimates the strength of the aerosol-cloud interactions in satellite data.

  16. In vivo dosimetry with semiconductor and thermoluminescent detectors applied to head and neck cancer treatment; Dosimetria in vivo com uso de detectores semicondutores e termoluminescentes aplicada ao tratamento de cancer de cabeca e pescoco

    Energy Technology Data Exchange (ETDEWEB)

    Viegas, Claudio Castelo Branco

    2003-03-15

    In vivo dosimetry in radiotherapy, i. e, the assessment of the doses received by patients during their treatments, permits a verification of the therapy quality. A routine of in vivo dosimetry is, undoubtedly, a direct benefit for the patient. Unfortunately, in Brazil and in Latin America this procedure is still a privilege for only a few patients. This routine is of common application only in developed countries. The aim of this work is to show the viability and implementation of a routine in vivo dosimetry, using diodes semiconductors and thermoluminescent dosimeters (TLD), at the radiotherapy section of the National Institute of Cancer in Brazil, in the case of head and neck cancer treatment. In order to reach that aim, the characteristics of the response of diodes ISORAD-p and LiF:Mg;Ti (TLD-100) thermoluminescent detectors in powder form were determined. The performance of those detectors for in vivo dosimetry was tested using an RANDO Alderson anthropomorfic phantom and, once their adequacy proved for the kind of measurements proposed, they were used for dose assessment in the case of tumour treatments in the head and neck regions, for Cobalt-60 irradiations. (author)

  17. Calibration procedure for thermoluminescent dosemeters in water absorbed doses for Iridium-192 high dose rate sources

    International Nuclear Information System (INIS)

    Reyes Cac, Franky Eduardo

    2004-10-01

    Thermoluminescent dosimeters are used in brachytherapy services quality assurance programs, with the aim of guaranteeing the correct radiation dose supplied to cancer patients, as well as with the purpose of evaluating new clinical procedures. This work describes a methodology for thermoluminescent dosimeters calibration in terms of absorbed dose to water for 192 Ir high dose rate sources. The reference dose used is measured with an ionization chamber previously calibrated for 192 Ir energy quality, applying the methodology proposed by Toelli. This methodology aims to standardizing the procedure, in a similar form to that used for external radiotherapy. The work evolves the adaptation of the TRS-277 Code of the International Atomic Energy Agency, for small and big cavities, through the introduction for non-uniform experimental factor, for the absorbed dose in the neighborhood of small brachytherapy sources. In order to simulate a water medium around the source during the experimental work, an acrylic phantom was used. It guarantees the reproducibility of the ionization chamber and the thermoluminescent dosimeter's location in relation to the radiation source. The values obtained with the ionization chamber and the thermoluminescent dosimeters, exposed to a 192 Ir high dose rate source, were compared and correction factors for different source-detector distances were determined for the thermoluminescent dosimeters. A numeric function was generated relating the correction factors and the source-detector distance. These correction factors are in fact the thermoluminescent dosimeter calibration factors for the 192 Ir source considered. As a possible application of this calibration methodology for thermoluminescent dosimeters, a practical range of source-detector distances is proposed for quality control of 192 Ir high dose rate sources. (author)

  18. Seasonal albedo of an urban/rural landscape from satellite observations

    Science.gov (United States)

    Brest, Christopher L.

    1987-01-01

    Using data from 27 calibrated Landsat observations of the Hartford, Connecticut area, the spatial distribution and seasonal variation of surface reflectance and albedo were examined. Mean values of visible reflectance, near-IR reflectance, and albedo are presented (for both snow-free and snow-cover observations) according to 14 land use/land cover categories. A diversity of albedo values was found to exist in this type of environment, associated with land cover. Many land-cover categories display a seasonal dependence, with intracategory seasonal differences being of comparable magnitude to intercategory differences. Key factors in determining albedo (and its seasonal dynamics) are the presence or absence of vegetation and the canopy structure. Snow-cover/snow-free differences range from a few percent (for urban land covers) to over 40 percent (for low-canopy vegetation).

  19. Quality assurance of in-situ measurements of land surface albedo: A model-based approach

    Science.gov (United States)

    Adams, Jennifer; Gobron, Nadine; Widlowski, Jean-Luc; Mio, Corrado

    2016-04-01

    This paper presents the development of a model-based framework for assessing the quality of in-situ measurements of albedo used to validate land surface albedo products. Using a 3D Monte Carlo Ray Tracing (MCRT) radiative transfer model, a quality assurance framework is built based on simulated field measurements of albedo within complex 3D canopies and under various illumination scenarios. This method provides an unbiased approach in assessing the quality of field measurements, and is also able to trace the contributions of two main sources of uncertainty in field-measurements of albedo; those resulting from 1) the field measurement protocol, such as height or placement of field measurement within the canopy, and 2) intrinsic factors of the 3D canopy under specific illumination characteristics considered, such as the canopy structure and landscape heterogeneity, tree heights, ecosystem type and season.

  20. The extreme ultraviolet albedos of the planet Mercury and of the moon

    Science.gov (United States)

    Wu, H. H.; Broadfoot, A. L.

    1977-01-01

    The albedo of the moon in the far UV was measured by Mariner 10 at a solar phase angle of 74 deg, and the geometric albedo of Mercury was measured in same wavelength range (584-1657 A) at solar phase angles ranging from 50 to 120 deg. For both the moon and Mercury there is a general increase in albedo for wavelengths decreasing from 1657 to 584 A. The ratio of the albedos of Mercury and the moon increases from about 0.6 to 0.8 in the range 600-1600 A. This merely points to a difference in the surfaces of the moon and Mercury, there being insufficient data to make any conclusions regarding the nature of the difference.

  1. Arctic sea ice albedo - A comparison of two satellite-derived data sets

    Science.gov (United States)

    Schweiger, Axel J.; Serreze, Mark C.; Key, Jeffrey R.

    1993-01-01

    Spatial patterns of mean monthly surface albedo for May, June, and July, derived from DMSP Operational Line Scan (OLS) satellite imagery are compared with surface albedos derived from the International Satellite Cloud Climatology Program (ISCCP) monthly data set. Spatial patterns obtained by the two techniques are in general agreement, especially for June and July. Nevertheless, systematic differences in albedo of 0.05 - 0.10 are noted which are most likely related to uncertainties in the simple parameterizations used in the DMSP analyses, problems in the ISCCP cloud-clearing algorithm and other modeling simplifications. However, with respect to the eventual goal of developing a reliable automated retrieval algorithm for compiling a long-term albedo data base, these initial comparisons are very encouraging.

  2. Offset of the potential carbon sink from boreal forestation by decreases in surface albedo

    International Nuclear Information System (INIS)

    Betts, R.A.

    2000-01-01

    Carbon uptake by forestation is one method proposed to reduce net carbon dioxide emissions to the atmosphere and so limit the radiative forcing of climate change. But the overall impact of forestation on climate will also depend on other effects associated with the creation of new forests. In particular the albedo of a forested landscape is generally lower than that of cultivated land, especially when snow is lying, and decreasing albedo exerts a positive radiative forcing on climate. Here I simulate the radiative forcings associated with changes in surface albedo as a result of forestation in temperate and boreal forest areas, and translate these forcings into equivalent changes in local carbon stock for comparison with estimated carbon sequestration potentials. I suggest that in many boreal forest areas, the positive forcing induced by decreases in albedo can offset the negative forcing that is expected from carbon sequestration. Some high-latitude forestation activities may therefore increase climate change, rather that mitigating it as intended

  3. Atmospheric effect on the ground-based measurements of broadband surface albedo

    Directory of Open Access Journals (Sweden)

    T. Manninen

    2012-11-01

    Full Text Available Ground-based pyranometer measurements of the (clear-sky broadband surface albedo are affected by the atmospheric conditions (mainly by aerosol particles, water vapour and ozone. A new semi-empirical method for estimating the magnitude of the effect of atmospheric conditions on surface albedo measurements in clear-sky conditions is presented. Global and reflected radiation and/or aerosol optical depth (AOD at two wavelengths are needed to apply the method. Depending on the aerosol optical depth and the solar zenith angle values, the effect can be as large as 20%. For the cases we tested using data from the Cabauw atmospheric test site in the Netherlands, the atmosphere caused typically up to 5% overestimation of surface albedo with respect to corresponding black-sky surface albedo values.

  4. Modeling Earth Albedo Currents on Sun Sensors for Improved Vector Observations

    DEFF Research Database (Denmark)

    Bhanderi, Dan

    2006-01-01

    Earth albedo influences vector measurements of the solar line of sight vector, due to the induced current on in the photo voltaics of Sun sensors. Although advanced digital Sun sensors exist, these are typically expensive and may not be suited for satellites in the nano or pico-class. Previously...... an Earth albedo model, based on reflectivity data from NASA's Total Ozone Mapping Spectrometer project, has been published. In this paper the proposed model is presented, and the model is sought validated by comparing simulated data with telemetry from the Danish Ørsted satellite. A novel method...... for modeling Sun sensor output by incorporating the Earth albedo model is presented. This model utilizes the directional information of in the Earth albedo model, which is achieved by Earth surface partitioning. This allows accurate simulation of the Sun sensor output and the results are consistent with Ørsted...

  5. Albedo-adjusted fast-neutron diffusion coefficients in reactor reflectors

    International Nuclear Information System (INIS)

    Terney, W.B.

    1975-01-01

    In the newer, larger pressurized-water reactor cores, the calculated power distributions are fairly sensitive to the number of neutron groups used and to the treatment of the reflector cross sections. Comparisons between transport and diffusion calculations show that the latter substantially underpredict the reflector albedos in the fast (top) group and that the power distribution is shifted toward the core center when compared to 4-group transport theory results. When the fast-neutron diffusion coefficients are altered to make the transport- and diffusion-theory albedos agree, the power distributions are also brought into agreement. An expression for the fast-neutron diffusion coefficients in reflector regions has been derived such that the diffusion calculation reproduces the albedo obtained from a transport solution. In addition, a correction factor for mesh effects applicable to coarse mesh problems is presented. The use of the formalism gives the correct albedos and improved power distributions. (U.S.)

  6. Role of albedo from the Gamma-400 telescope calorimeter when recording the primary gamma emission.

    Science.gov (United States)

    Ginsburg, V. L.; Kurnosova, L. V.; Labensky, A. G.; Topchiev, N. P.; Fradkin, M. I.; Kaplin, V. A.; Kaplin, D. V.; Loginov, V. A.; Maklyaev, E. F.; Runtso, M. F.; Gorchakov, E. V.

    A calorimeter albedo emission affecting the Gamma-400 telescope operation is studied, when recording γ-quanta at energies from 10 to 1000 GeV. Methods for diminishing this impact on measuring data are proposed.

  7. DUST, Albedo Monte-Carlo Simulation of Neutron Streaming in Multi-legged Square Concrete Ducts

    International Nuclear Information System (INIS)

    1993-01-01

    1 - Description of program or function: DUST simulates the thermal neutron streaming through multi-legged square concrete ducts. 2 - Method of solution: DUST uses the albedo Monte Carlo method. The albedo data used are in the form of empirical formulae based on the measured doubly differential albedo data. Sampling of the reflected polar and azimuthal angles is done by the rejection method. Variance reduction devices such as Russian Roulette are used. 3 - Restrictions on the complexity of the problem: - The albedo data and the subroutines for sampling the reflected polar and azimuthal angles are specific for concrete ducts. The maximum number of legs (as specified by dimension statements) is 5 and the maximum number of dose points is 50. The dose points considered are only in the last leg of the multi-legged duct

  8. Glacier albedo decrease in the European Alps: potential causes and links with mass balances

    Science.gov (United States)

    Di Mauro, Biagio; Julitta, Tommaso; Colombo, Roberto

    2016-04-01

    Both mountain glaciers and polar ice sheets are losing mass all over the Earth. They are highly sensitive to climate variation, and the widespread reduction of glaciers has been ascribed to the atmospheric temperature increase. Beside this driver, also ice albedo plays a fundamental role in defining mass balance of glaciers. In fact, dark ice absorbs more energy causing faster glacier melting, and this can drive to more negative balances. Previous studies showed that the albedo of Himalayan glaciers and the Greenland Ice Sheet is decreasing with important rates. In this contribution, we tested the hypothesis that also glaciers in the European Alps are getting darker. We analyzed 16-year time series of MODIS (MODerate resolution Imaging Spectrometer) snow albedo from Terra (MOD13A1, 2000-2015) and Aqua (MYD13A1, 2002-2015) satellites. These data feature a spatial resolution of 500m and a daily temporal resolution. We evaluated the existence of a negative linear and nonlinear trend of the summer albedo values both at pixel and at glacier level. We also calculated the correlation between MODIS summer albedo and glacier mass balances (from the World Glaciological Monitoring Service, WGMS database), for all the glaciers with available mass balance during the considered period. In order to estimate the percentage of the summer albedo that can be explained by atmospheric temperature, we correlated MODIS albedo and monthly air temperature extracted from the ERA-Interim reanalysis dataset. Results show that decreasing trends exist with a strong spatial variability in the whole Alpine chain. In large glaciers, such as the Aletch (Swiss Alps), the trend varies significantly also within the glacier, showing that the trend is higher in the area across the accumulation and ablation zone. Over the 17 glaciers with mass balance available in the WGMS data set, 11 gave significant relationship with the MODIS summer albedo. Moreover, the comparison between ERA-Interim temperature

  9. Implications of albedo changes following afforestation on the benefits of forests as carbon sinks

    Directory of Open Access Journals (Sweden)

    M. U. F. Kirschbaum

    2011-12-01

    Full Text Available Increased carbon storage with afforestation leads to a decrease in atmospheric carbon dioxide concentration and thus decreases radiative forcing and cools the Earth. However, afforestation also changes the reflective properties of the surface vegetation from more reflective pasture to relatively less reflective forest cover. This increase in radiation absorption by the forest constitutes an increase in radiative forcing, with a warming effect. The net effect of decreased albedo and carbon storage on radiative forcing depends on the relative magnitude of these two opposing processes.

    We used data from an intensively studied site in New Zealand's Central North Island that has long-term, ground-based measurements of albedo over the full short-wave spectrum from a developing Pinus radiata forest. Data from this site were supplemented with satellite-derived albedo estimates from New Zealand pastures. The albedo of a well-established forest was measured as 13 % and pasture albedo as 20 %. We used these data to calculate the direct radiative forcing effect of changing albedo as the forest grew.

    We calculated the radiative forcing resulting from the removal of carbon from the atmosphere as a decrease in radiative forcing of −104 GJ tC−1 yr−1. We also showed that the observed change in albedo constituted a direct radiative forcing of 2759 GJ ha−1 yr−1. Thus, following afforestation, 26.5 tC ha−1 needs to be stored in a growing forest to balance the increase in radiative forcing resulting from the observed albedo change. Measurements of tree biomass and albedo were used to estimate the net change in radiative forcing as the newly planted forest grew. Albedo and carbon-storage effects were of similar magnitude for the first four to five years after tree planting, but as the stand grew older, the carbon storage effect increasingly dominated. Averaged over the whole

  10. Estimation of snow albedo reduction by light absorbing impurities using Monte Carlo radiative transfer model

    Science.gov (United States)

    Sengupta, D.; Gao, L.; Wilcox, E. M.; Beres, N. D.; Moosmüller, H.; Khlystov, A.

    2017-12-01

    Radiative forcing and climate change greatly depends on earth's surface albedo and its temporal and spatial variation. The surface albedo varies greatly depending on the surface characteristics ranging from 5-10% for calm ocean waters to 80% for some snow-covered areas. Clean and fresh snow surfaces have the highest albedo and are most sensitive to contamination with light absorbing impurities that can greatly reduce surface albedo and change overall radiative forcing estimates. Accurate estimation of snow albedo as well as understanding of feedbacks on climate from changes in snow-covered areas is important for radiative forcing, snow energy balance, predicting seasonal snowmelt, and run off rates. Such information is essential to inform timely decision making of stakeholders and policy makers. Light absorbing particles deposited onto the snow surface can greatly alter snow albedo and have been identified as a major contributor to regional climate forcing if seasonal snow cover is involved. However, uncertainty associated with quantification of albedo reduction by these light absorbing particles is high. Here, we use Mie theory (under the assumption of spherical snow grains) to reconstruct the single scattering parameters of snow (i.e., single scattering albedo ῶ and asymmetry parameter g) from observation-based size distribution information and retrieved refractive index values. The single scattering parameters of impurities are extracted with the same approach from datasets obtained during laboratory combustion of biomass samples. Instead of using plane-parallel approximation methods to account for multiple scattering, we have used the simple "Monte Carlo ray/photon tracing approach" to calculate the snow albedo. This simple approach considers multiple scattering to be the "collection" of single scattering events. Using this approach, we vary the effective snow grain size and impurity concentrations to explore the evolution of snow albedo over a wide

  11. tgcd: An R package for analyzing thermoluminescence glow curves

    Directory of Open Access Journals (Sweden)

    Jun Peng

    2016-01-01

    Full Text Available Thermoluminescence (TL glow curves are widely used in dosimetric studies. Many commercial and free-distributed programs are used to deconvolute TL glow curves. This study introduces an open-source R package tgcd to conduct TL glow curve analysis, such as kinetic parameter estimation, glow peak simulation, and peak shape analysis. TL glow curves can be deconvoluted according to the general-order empirical expression or the semi-analytical expression derived from the one trap-one recombination center (OTOR model based on the Lambert W function by using a modified Levenberg–Marquardt algorithm from which any of the parameters can be constrained or fixed. The package provides an interactive environment to initialize parameters and offers an automated “trial-and-error” protocol to obtain optimal fit results. First-order, second-order, and general-order glow peaks (curves are simulated according to a number of simple kinetic models. The package was developed using a combination of Fortran and R programming languages to improve efficiency and flexibility.

  12. Thermoluminescent analysis of archaeological ceramic from Teotenango, Mexico

    International Nuclear Information System (INIS)

    Dominguez R, R.; Mondragon, M.; Villa S, G.; Gonzalez M, P.R.; Mendoza A, D.

    2006-01-01

    Of all the kind of artifacts which may be found at archaeological sites, ceramics are surely among the most important. A ceramic material is highly durable, and virtually unchanged after hundred of years from its date of manufacture. Because of this, a ceramic will always be an important object for serious studies to determine which culture produced it, to date cultures, reconstruct economic patterns and social organization, and establish routes of trade or simply to classify the different types of ceramics. The aim of this paper was to perform a thermoluminescent analysis of archaeological ceramic samples belonging to Teotenango, Mexico. The analysis is complemented with a physicochemical characterization by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD). TL analysis shows some differences when the samples are exposed to ionizing radiation field, while SEM analysis shows a porous and granular structure in all samples, EDS analysis shows oxygen (O), aluminum (Al), silicon (Si), iron (Fe), sodium (Na), phosphorus (P), potassium (K) and calcium (Ca) in significant amounts. These results allow establishing differences among ceramic samples belonging to the same place. (Author)

  13. Thermoluminescent analysis of archaeological ceramic from Teotenango, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez R, R. [Centro INAH Estado de Mexico, Morelos Ote. 502, Col. San Sebastian, 50090 Toluca, Estado de Mexico (Mexico); Mondragon, M. [Museo Roman Pina Chan, Teotenango 1024 (Mexico); Villa S, G.; Gonzalez M, P.R.; Mendoza A, D. [ININ, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2006-07-01

    Of all the kind of artifacts which may be found at archaeological sites, ceramics are surely among the most important. A ceramic material is highly durable, and virtually unchanged after hundred of years from its date of manufacture. Because of this, a ceramic will always be an important object for serious studies to determine which culture produced it, to date cultures, reconstruct economic patterns and social organization, and establish routes of trade or simply to classify the different types of ceramics. The aim of this paper was to perform a thermoluminescent analysis of archaeological ceramic samples belonging to Teotenango, Mexico. The analysis is complemented with a physicochemical characterization by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD). TL analysis shows some differences when the samples are exposed to ionizing radiation field, while SEM analysis shows a porous and granular structure in all samples, EDS analysis shows oxygen (O), aluminum (Al), silicon (Si), iron (Fe), sodium (Na), phosphorus (P), potassium (K) and calcium (Ca) in significant amounts. These results allow establishing differences among ceramic samples belonging to the same place. (Author)

  14. Reproducibility Test for Thermoluminescence Dosimeter (TLD) Using TLD Radpro

    International Nuclear Information System (INIS)

    Nur Khairunisa Zahidi; Ahmad Bazlie Abdul Kadir; Faizal Azrin Abdul Razalim

    2016-01-01

    Thermoluminescence dosimeters (TLD) as one type of dosimeter which are often used to substitute the film badge. Like a film badge, it is worn for a period of time and then must be processed to determine the dose received. This study was to test the reproducibility of TLD using Radpro reader. This study aimed to determine the dose obtained by TLD-100 chips when irradiated with Co-60 gamma source and to test the effectiveness of TLD Radpro reader as a machine to analyse the TLD. Ten chips of TLD -100 were irradiated using Eldorado machine with Co-60 source at a distance of 5 meters from the source with 2 mSv dose exposure. After the irradiation process, TLD-100 chips were read using the TLD Radpro reader. These steps will be repeated for nine times to obtain reproducibility coefficient, r i . The readings of dose obtained from experiment was almost equivalent to the actual dose. Results shows that the average value obtained for reproducibility coefficient, r i is 6.39 % which is less than 10 %. As conclusion, the dose obtained from experiment considered accurate because its value were almost equivalent to the actual dose and TLD Radpro was verified as a good reader to analyse the TLD. (author)

  15. Percentage depth dose evaluation in heterogeneous media using thermoluminescent dosimetry

    Science.gov (United States)

    da Rosa, L.A.R.; Campos, L.T.; Alves, V.G.L.; Batista, D.V.S.; Facure, A.

    2010-01-01

    The purpose of this study is to investigate the influence of lung heterogeneity inside a soft tissue phantom on percentage depth dose (PDD). PDD curves were obtained experimentally using LiF:Mg,Ti (TLD‐100) thermoluminescent detectors and applying Eclipse treatment planning system algorithms Batho, modified Batho (M‐Batho or BMod), equivalent TAR (E‐TAR or EQTAR), and anisotropic analytical algorithm (AAA) for a 15 MV photon beam and field sizes of 1×1,2×2,5×5, and 10×10cm2. Monte Carlo simulations were performed using the DOSRZnrc user code of EGSnrc. The experimental results agree with Monte Carlo simulations for all irradiation field sizes. Comparisons with Monte Carlo calculations show that the AAA algorithm provides the best simulations of PDD curves for all field sizes investigated. However, even this algorithm cannot accurately predict PDD values in the lung for field sizes of 1×1 and 2×2cm2. An overdosage in the lung of about 40% and 20% is calculated by the AAA algorithm close to the interface soft tissue/lung for 1×1 and 2×2cm2 field sizes, respectively. It was demonstrated that differences of 100% between Monte Carlo results and the algorithms Batho, modified Batho, and equivalent TAR responses may exist inside the lung region for the 1×1cm2 field. PACS number: 87.55.kd

  16. Radiation Effects on Thermoluminescence Characteristics of HDPE Containing Additives

    International Nuclear Information System (INIS)

    Kim, Ki Yup; Lee, Chung; Ryu, Boo Hyung

    2005-01-01

    Polymeric materials are widely used for electrical insulation in a broad range of applications that cover the power supply industry to inner and outer space. However, the electrical performance of these materials could be compromised by their working environment and one of the most deleterious is that where a nuclear radiation is present. Radiation effects on polymers can be interpreted by two main reactions, a cross-linking reaction and degradation reactions or a main-chain scission process. There are no absolute rules for determining whether or not any given polymer will cross-link or degrade upon an irradiation. But, the polymers can be divided empirically into two groups; polymers which are crosslinked by radiation (especially by the incorporation of chemical cross-linking promoters) and polymers which degrade by radiation into a product of lower molecular weight due to random main-chain scission process. These polymers become very hard and brittle with a high dose of radiation. Most polymeric materials contain some stabilizers such as flame retardant and antioxidant to prevent combustion and oxidation. Because of these additives, degradation mechanism of the polymer became complicated. Many of the novel properties of the insulating materials used in nuclear power plants are important for radiation degradation. Therefore we have used the thermal methods such as thermoluminescence (TL) detection for irradiated high density polyethylene containing flame retardant and antioxidant

  17. CVD diamonds as thermoluminescent detectors for medical applications

    International Nuclear Information System (INIS)

    Marczewska, B.; Olko, P.; Nesladek, M.; Waligorski, M.P.R.; Kerremans, Y.

    2002-01-01

    Diamond is believed to be a promising material for medical dosimetry due to its tissue equivalence, mechanical and radiation hardness, and lack of solubility in water or in disinfecting agents. A number of diamond samples, obtained under different growth conditions at Limburg University, using the chemical vapour deposition (CVD) technique, was tested as thermoluminescence dosemeters. Their TL glow curve, TL response after doses of gamma rays, fading, and so on were studied at dose levels and for radiation modalities typical for radiotherapy. The investigated CVD diamonds displayed sensitivity comparable with that of MTS-N (Li:Mg,Ti) detectors, signal stability (reproducibility after several readouts) below 10% (1 SD) and no fading was found four days after irradiation. A dedicated CVD diamond plate was grown, cut into 20 detector chips (3x3x0.5 mm) and used for measuring the dose-depth distribution at different depths in a water phantom, for 60 Co and six MV X ray radiotherapy beams. Due to the sensitivity of diamond to ambient light, it was difficult to achieve reproducibility comparable with that of standard LiF detectors. (author)

  18. Effect of the radiation in the thermoluminescent properties of lava

    CERN Document Server

    Correcher, V; García, J

    2003-01-01

    Blue thermoluminescence (Tl) emission from different lavas of many places (Costa Rica, Canary Islands, Hawaii Islands, Iceland and Italy) corresponding to different eruptions has been studied to know its potential use in the field of dating and retrospective dosimetry. Due to the light emission is linked to the point defects of the crystalline lattice structure, X-ray diffraction analyses were performed to determine the components of this poly mineral material that mostly are cristobalite, plagioclase and phyllosilicates. Exposures to different doses (in a range of 1-25 Gy) were given to each sample to determine the evolution of the Tl signal with the irradiation under laboratory conditions. In all cases, a linear response could be observed and no saturation has been detected in this range of doses. Both natural (NTL) and induced (ITL) Tl signal exhibit a complex glow curve structure associated to a continuous trap distribution over 100 C that could be attributed to the formation-annihilation [Al0 sub 4 /alka...

  19. Thermoluminescence dosimetry of electronic components from personal objects

    International Nuclear Information System (INIS)

    Beerten, Koen; Woda, Clemens; Vanhavere, Filip

    2009-01-01

    Owing to the existence of ceramic materials inside common personal objects such as cellular phones and USB flash drives, these objects may be very useful in emergency (accident) dosimetry. Here we will present initial results regarding the dosimetric properties as determined by thermoluminescence (TL) from two alumina-rich electronic components from a USB flash drive. The TL method was applied in order to investigate the potential of conventional TL equipment for such purposes. For comparison, the optically stimulated luminescence (OSL) of the components was investigated as well. The studied components are ceramic resonators and alumina-based substrates from electrical resistors. The results show that various TL-related properties such as fading, optical stability and zero-dose response are different for the two investigated components. On the basis of these properties, the ceramic resonator was selected for dose recovery tests using TL and OSL. The given dose could reliably be determined using both methods, assuming that prompt measurement and/or fading correction is possible.

  20. Practical use of lithium borate in thermoluminescent dosimetry

    International Nuclear Information System (INIS)

    Chavaudra, J.; Nguyen, J.; Marinello, G.; Brule, A.M.

    1976-01-01

    The functional principles of thermoluminescent dosimeters are recalled: heating, apparatus for measuring the emitted light, circulation of nitrogen, reference source. The essential role played by the circulation of nitrogen over the dosimeters which equilibrates the temperature of the photomultiplier, reduces the emission of unwanted light, prevents the combustion of dust or other possible impurities and finally improves the accuracy of the measurements even for high doses, is underlined. Lithium borate is taken as an example and a simple method for finding the optimum working conditions for the heating apparatus of the planchette in the most simple T.L.D. readers and in those where the heating apparatus of the planchette has a pre-heating phase is proposed. The dosimetric properties of lithium borate incorporated in thin teflon discs (type DLB. 0.13 and 0.4) are studied. This shows itself to be very interesting for certain uses because it is a solid dosimeter which does not require annealing between two measurements. The accuracy of the measurements obtained with this material, the stability of the response relative to the delay between radiation and reading (fading), the response relative to the absorbed dose plus the nature and the energy of the rays, are presented with the usual reservations made for this type of dosimetry [fr

  1. Thermoluminescence characterization of the irradiated minerals extracted from nopal

    Science.gov (United States)

    Cruz-Zaragoza, E.; Furetta, C.; Kitis, G.; Gomez, B. T.; Polymeris, G. S.; Tsirliganis, N.; Loukou, Z.

    2006-05-01

    The mineral fraction from dehydrated nopal leaves (Opuntia ficus indica ) belonging to the Cactaceae family was extracted and selected by sizes of 10 and 74 mu m and exposed to 60 Co gamma radiation at different doses in the range 70 Gy-20 kGy. The glow-curves from these polyminerals show a thermoluminescence (TL) band with one very intense peak at a temperature around 150 degrees C and a second one emerging in the high temperature region, moving in a large zone of temperature values according to the preparation used and the level of irradiation. The XRD analysis shows a composition of both biominerals as whewellite and weddellite and a mineral fraction as anorthoclase and quartz. The main TL characteristics of the polymineral content of the nopal was analyzed, i.e . the TL response at different doses and fading during storage at room temperature. The activation energy of the traps responsible for the TL emission was also investigated and a possible continuous distribution of traps is discussed. A review of the scientific literature shows that this is the first time that a TL study on nopal ionized by irradiation has been carried out.

  2. Thermoluminescent study of the hydroxyapatite irradiated with gamma radiation

    International Nuclear Information System (INIS)

    Mendoza A, D.; Hernandez A, M.; Gonzalez, P.R.; Rodriguez L, V.

    2002-01-01

    Recently in dosimetry, it has been common to use bones and teeth for detecting and measuring radiation. However it has been observed that the efficiency of detection depends on the consistency of these tissues. Since the hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] is the main mineral component of the bones and teeth, it has been suggested as material for detecting and measuring of radiations, quantifying the free radicals produced by radiation. In this work a study about the thermoluminescent properties (Tl) induced by radiation in the synthetic hydroxyapatite obtained by hydrothermal method is presented. The results have shown that this mineral presents a Tl signal whose curve contains two maximums located around 150 and 250 C degrees, respectively. Likewise, a linear behavior of the Tl signal of function of dose in the interval 10-100 Gy was observed. These results are important since that they open the possibility to use biomaterials in the dosimetric area, when they only were used for grafting in the biomedical area. (Author)

  3. Thermoluminescence dosimetry in quality imaging in CR mammography systems

    Energy Technology Data Exchange (ETDEWEB)

    Gaona, E.; Franco E, J.G. [UAM-Xochimilco, 04960 Mexico D.F. (Mexico); Azorin N, J. [UAM-Iztapalapa, 09340 Mexico D.F. (Mexico); Diaz G, J.A.I. [CICATA, Unidad Legaria, Av. Legaria 694, 11599 mexico D.F. (Mexico); Arreola, M. [Department of Radiology, Shands Hospital at UF, PO Box 100374, Gainesville, FL 32610-0374 (United States)

    2006-07-01

    The aim of this work is to estimate the average glandular dose with Thermoluminescence Dosimetry (TLD) and comparison with quality imaging in CR mammography. For measuring dose, FDA and ACR use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, Full Field Digital Mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one CR mammography system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium fluoro halide. We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated x-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose that overcomes 3.0 mGy and it doesn't improve the image quality and dose to the breast will be excessive. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement. (Author)

  4. Thermoluminescence in films of HfO2:Dy+3

    International Nuclear Information System (INIS)

    Ceron, P.; Rivera, T.; Guzman, J.; Montes, E.; Pelaez, A.; Rojas, B.; Guzman, D.; Azorin, J.; Paredes, L.

    2014-08-01

    In this work the thermoluminescence (TL) response of films of hafnium oxide polluted with dysprosium (HfO 2 :Dy +3 ) that were irradiated in the near UV (200 nm - 400 nm). The films were deposited by means of the ultrasonics spray pyrolysis technique on a glass substrate, using different deposit temperatures (300 grades C - 600 grades C). The best TL emission corresponded to the prepared film to 450 grades C that was exposed to a spectral irradiation of 80 μJ/(cm 2 -s) with a wave longitude of 240 nm. The TL response in function of the spectral irradiation was lineal in the studied interval (24 to 288 mJ/cm 2 ), several kinetic parameters were also calculated of the shine curve as depth of the trap (E), frequency factor (s) and order to the kinetics (b). The obtained results show that the films of HfO 2 :Dy +3 could be used as radiation monitor in the region of the near UV. (Author)

  5. Thermoluminescence of Z1 centres in Sr-doped KCl

    International Nuclear Information System (INIS)

    Kamavisdar, V.S.; Moholkar, S.C.; Deshmukh, B.T.

    1980-01-01

    It is well known for alkali halides doped with divalent metal impurities that exposure to high energetic radiation and subsequent F band bleaching leads to the formation of Z 1 centres. Optical absorption measurements have shown that a low concentration of Z 1 centres is produced along with F centres during irradiation without any optical bleaching. Now the question is whether Z 1 centres are really formed along with F centres during irradiation. The aim of the present paper was to study the formation of a small amount of Z 1 centres during irradiation with the help of optical absorption and thermoluminescence measurements. The crystals of KCl:Sr were exposed to γ-rays for different doses. The TL curve for the crystal exposed to a minimum dose of γ-rays shows a TL peak at 457 K and a weak shoulder in the region 400 K to 408 K. The TL curve of the crystal exposed to maximum dose of rays shows the peak at 408 K with a greater intensity. Upon F band bleaching 408 K peak increases in intensity and optical absorption is also broadened. It is shown that the peak at 457 K is due to F centres and the peak at 408 K is due to Z 1 centres. These results clearly show that a small anount of Z 1 centres is really formed along with F centres during irradiation. (author)

  6. Radioluminescence and thermoluminescence of albite at low temperature

    International Nuclear Information System (INIS)

    Can, N.; Garcia-Guinea, J.; Kibar, R.; Cetin, A.; Ayvacikli, M.; Townsend, P.D.

    2011-01-01

    Feldspar as an archaeological and geological natural material for dating and retrospective dosimetry is receiving more and more attention because of its useful luminescence properties. In this study, the 25-280 K thermoluminescence (TL) and radioluminescence (RL) spectra in albite, which is a component of the two main feldspar series, the alkali feldspar (Na, K)AlSi 3 O 8 and the plagioclases (NaAlSi 3 O 8 -CaAl 2 Si 2 O 8 ) have been presented for aliquots along (001) and (010) crystallographic orientations. There are four main emission bands that are considered to arise from complexes of intrinsic defects linked in larger complexes with impurities such as Na + , Mn 2+ or Fe 3+ ions. The consequence of their association is to produce different luminescence efficiencies that produce wavelength sensitive TL curves. Radioluminescence data at low temperature for albites is distorted by contributions from the TL sites, even when the RL is run in a cooling cycle. This indicates the potential for a far more general problem for analysis of low temperature RL in insulating materials. - Highlights: → TL and RL spectra in albite were presented for different orientations. → There are 4 emission bands that are considered to arise from complexes of intrinsic. → RL data at low temperature for albite is distorted by contributions from TL sites. → This indicates the potential problem for analysis of low temperature RL.

  7. Thermoluminescent dose measurements on board Salyut type orbital stations

    International Nuclear Information System (INIS)

    Akatov, Yu.A.; Arkhangelskij, V.V.; Aleksandrov, A.P.

    1984-06-01

    A small, vibration- and shock-resistant thermoluminescent dosemeter (TLD) system - named PILLE - was developed for orbital stations at the Central Research Institute for Physics, Hungary, to measure the cosmic radiation dose on-board. The first on-board measurements with this system were performed by B. Farkas, the Hungarian astronaut, on the Salyut-6 space station in 1980. The same instrument was used by other crews in the following years. Doses measured at different sites in Salyut-6 are presented. The dose rates varied from 0.7 to 0.11 mGy.day -1 . After the first cosmic measurements, the system was further developed. The minimum detectable dose of the new TLD system is 1 μGy, i.e. less by one order of magnitude than that of the former system. The self-irradiation dose rate of the TLD bulbs is also reduced by more than an order of magnitude to 10 nGy.h -1 , by use of potassium-free glass for the bulb envelope. This new type of PILLE TLD system is currently on-board Salyut-7. The dose rates (0.12-0.23 mGy.day -1 ) measured in 1983 are presented in detail. (author)

  8. Import control of irradiated foods by the thermoluminescence method

    International Nuclear Information System (INIS)

    Pinnioja, S.; Autio, T.; Niemi, E.; Pensala, O.

    1993-01-01

    A thermoluminescence (TL) method was applied for the import control of irradiated foods. The method is based on the determination of the TL of mineral contaminants in foods. Detection of irradiation was incorporated in official Finnish control procedures in spring 1990. For foodstuffs with a reduced microbe content and in which no fumigant residues are found, possible irradiation is investigated by the TL method. The minerals are separated from the foods in different ways: picking is used for spices; water rinsing for herbs, spices, berries and mushrooms; high-density liquid to separate the organic material from the mineral fraction in seafood; and carbon tetrachloride for foods forming gels with water. To date about 140 food samples have been analysed for control purposes: 50 samples of herbs and spices, 25 samples of berries and mushrooms and 65 samples of seafood. Of these, 14 samples of herbs and spices and 5 samples of seafood were shown to have been irradiated. Differences in TL intensity between irradiated and unirradiated samples were at least 1 and usually 3-4 orders of magnitude. (orig.)

  9. An algorithm for unified analysis on the thermoluminescence glow curve

    International Nuclear Information System (INIS)

    Chung, K.S.; Park, C.Y.; Lee, J.I.; Kim, J.L.

    2014-01-01

    An algorithm was developed to integrally handle excitation by radiation, relaxation and luminescence by thermal or optical stimulation in thermoluminescence (TL) and optically stimulated luminescence (OSL) processes. This algorithm reflects the mutual interaction between traps through a conduction band. Electrons and holes are created by radiation in the beginning, and these electrons move to the trap through the conduction band. These holes move to the recombination center through a valence band. The ratio of the electrons allocated to each trap differs with the recombination probability and these values also relevant to the process of luminescence. Accordingly, the glow curve can be interpreted by taking the rate of electron–hole pairs created by ionizing radiation as a unique initial condition. This method differs from the conventional method of interpreting the measured glow curve with the initial electron concentration allocated to each trap at the end of irradiation. A program using the Visual Studio's C# subsystem was made to realize such a developed algorithm. To verify this algorithm it was applied to LiF:Mg,Cu,Si. The TL glow curve was deconvoluted with a model of five traps, one deep trap and one recombination center (RC). - Highlights: • TL glow curve deconvolution employing interacting model. • Simulation both irradiation and TL readout stages for various dose level. • Application in the identification TL kinetics of LiF:Mg,Cu,Si TLD

  10. Thermoluminescence as a dating method applied to the Morocco Neolithic

    International Nuclear Information System (INIS)

    Ousmoi, M.

    1989-09-01

    Thermoluminescence is an absolute dating method which is well adapted to the study of burnt clays and so of the prehistoric ceramics belonging to the Neolithic period. The purpose of this study is to establish a first absolute chronology of the septentrional morocco Neolithic between 3000 and 7000 years before us and some improvements of the TL dating. The first part of the thesis contains some hypothesis about the morocco Neolithic and some problems to solve. Then we study the TL dating method along with new process to ameliorate the quality of the results like the shift of quartz TL peaks or the crushing of samples. The methods which were employed using 24 samples belonging to various civilisations are: the quartz inclusion method and the fine grain technique. For the dosimetry, several methods were used: determination of the K 2 O contents, alpha counting, site dosimetry using TL dosimeters and a scintillation counter. The results which were found bring some interesting answers to the archeologic question and ameliorate the chronologic schema of the Northern morocco Neolithic: development of the old cardial Neolithic in the North, and perhaps in the center of Morocco (the region of Rabat), between 5500 and 7000 before us. Development of the recent middle Neolithic around 4000-5000 before us, with a protocampaniforme (Skhirat), little older than the campaniforme recognized in the south of Spain. Development of the bronze age around 2000-4000 before us [fr

  11. Bleaching of the thermoluminescence of feldspars by sunlight

    International Nuclear Information System (INIS)

    Robertson, G.B.; Prescott, J.R.; Hutton, J.T.

    1991-01-01

    Feldspars are an important component of materials used for thermoluminescence (TL) and photoluminescence (PL) dating of sediments; and successful dating implies a knowledge of the degree of re-setting by exposure to sunlight of the stored luminescence energy. We have studied the bleaching by full sunlight of the TL of six alkali feldspars of representative composition and of one oligoclase. The high potassium and high sodium feldspars are the brightest, and are also the least easily bleached, whereas those of intermediate (K-Na) composition bleach quickly. On a time scale of upwards of 16 h, all samples would have bleached enough for them to be useful for TL dating. A search was made for individual glow curve peaks that bleach particularly quickly (and are thus similar to the well-known 325 o C peak used in the TL dating of quartz). In the samples studied, there was only one glow curve peak that was selectively susceptible to bleaching: the 280 o C peak in oligoclase. (author)

  12. Thermoluminescence dosimetry in quality imaging in CR mammography systems

    International Nuclear Information System (INIS)

    Gaona, E.; Franco E, J.G.; Azorin N, J.; Diaz G, J.A.I.; Arreola, M.

    2006-01-01

    The aim of this work is to estimate the average glandular dose with Thermoluminescence Dosimetry (TLD) and comparison with quality imaging in CR mammography. For measuring dose, FDA and ACR use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, Full Field Digital Mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one CR mammography system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium fluoro halide. We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated x-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose that overcomes 3.0 mGy and it doesn't improve the image quality and dose to the breast will be excessive. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement. (Author)

  13. Thermoluminescence studies of natural and doped calcium fluoride phosphors

    International Nuclear Information System (INIS)

    El Kolaly, M.A.

    1977-01-01

    The various aspects of thermoluminescence (TL) of calcium fluoride phosphors obtained both from natural and laboratory-grown CaF 2 crystals have been investigated in the temperature range from room temperature to 750 deg C. Dopants used in these studies were Mn, Y and lanthanide series rare earths. The aspects which have been investigated are : (1) effect of single and double doping on TL glow curves and TL emission spectra after gamma irradiation, (2) TL traps : their kinetics including evaluation of the activation energy using different techniques, their decay kinetics and their behaviour under partially filled conditions, and (3) effect of temperature on emission of intensity of X-ray induced luminescence and TL. During the course of these investigations, a new glow peak was observed at 650 deg C in natural CaF 2 . It was found that this peak could also be produced in synthetic CaF 2 doped with (Y + Sm). A new model for the TL trap has also been proposed. (M.G.B.)

  14. Thermoluminescence in CVD diamond films: application to actinometric dosimetry

    International Nuclear Information System (INIS)

    Barboza-Flores, M.; Melendrez, R.; Chernov, V.; Castaneda, B.; Pedroza-Montero, M.; Gan, B.; Ahn, J.; Zhang, Q.; Yoon, S.F.

    2002-01-01

    Diamond is considered a tissue-equivalent material since its atomic number (Z=6) is close to the effective atomic number of biological tissue (Z=7.42). Such a situation makes it suitable for radiation detection purposes in medical applications. In the present work the analysis is reported of the thermoluminescence (TL) and dosimetric features of chemically vapour deposited (CVD) diamond film samples subjected to ultraviolet (UV) irradiation in the actinometric region. The TL glow curve shows peaks at 120, 220, 320 and 370 deg. C. The 120 and 370 deg. C peaks are too weak and the first one fades away in a few seconds after exposure. The overall room temperature fading shows a 50% TL decay 30 min after exposure. The 320 deg. C glow peak is considered to be the most adequate for dosimetric applications due to its low fading and linear TL behaviour as a function of UV dose in the 180-260 nm range. The TL excitation spectrum presents a broad band with at least two overlapped components around 205 and 220 nm. The results indicate that the TL behaviour of CVD diamond film can be a good alternative to the currently available dosemeter and detector in the actinometric region as well as in clinical and medical applications. (author)

  15. Systematic development of new thermoluminescence and optically stimulated luminescence materials

    Energy Technology Data Exchange (ETDEWEB)

    Yukihara, E.G., E-mail: eduardo.yukihara@okstate.edu [Physics Department, 145 Physical Sciences II, Oklahoma State University, Stillwater, OK 74078 (United States); Milliken, E.D.; Oliveira, L.C. [Physics Department, 145 Physical Sciences II, Oklahoma State University, Stillwater, OK 74078 (United States); Orante-Barron, V.R. [Departamento de Investigacion en Polimeros y Materiales, Universidad de Sonora, Hermosillo, Sonora 83000, Mexico (Mexico); Jacobsohn, L.G. [Center for Optical Materials Science and Engineering Technologies (COMSET), and School of Materials Science and Engineering, Clemson University, Clemson, SC (United States); Blair, M.W. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-01-15

    This paper presents an overview of a systematic study to develop new thermoluminescence (TL) and optically stimulated luminescence (OSL) materials using solution combustion synthesis (SCS) for applications such as personal OSL dosimetry, 2D dose mapping, and temperature sensing. A discussion on the material requirements for these applications is included. We present X-ray diffraction (XRD) data on single phase materials obtained with SCS, as well as radioluminescence (RL), TL and OSL data of lanthanide-doped materials. The results demonstrate the possibility of producing TL and OSL materials with sensitivity similar to or approaching those of commercial TL and OSL materials used in dosimetry (e.g., LiF:Mg,Ti and Al{sub 2}O{sub 3}:C) using SCS. The results also show that the luminescence properties can be improved by Li co-doping and annealing. The presence of an atypical TL background and anomalous fading are discussed and deserve attention in future investigations. We hope that these preliminary results on the use of SCS for production of TL and OSL materials are helpful to guide future efforts towards the development of new luminescence materials for different applications. - Highlights: Black-Right-Pointing-Pointer TL and OSL material produced with sensitivity similar to commercial materials. Black-Right-Pointing-Pointer Luminescence properties improved by Li co-doping and annealing. Black-Right-Pointing-Pointer The presence of atypical TL background and anomalous fading observed.

  16. γ radiation thermoluminescence performance of HFCVD diamond films

    International Nuclear Information System (INIS)

    Gastelum, S.; Cruz-Zaragoza, E.; Melendrez, R.; Chernov, V.; Barboza-Flores, M.

    2006-01-01

    Polycrystalline chemically vapor deposited (CVD) diamond films have been proposed as detectors and dosimeters of ionizing radiation with prospective applications in high-energy photon dosimetry applications. We present a comparison study on the thermoluminescence (TL) properties of two diamond film samples grown by the hot filament CVD method having thickness of 180 and 500 μm and exposed to γ radiation in the 1-300 Gy dose range. The 180 μm thick sample deposited on silicon substrate displayed a TL glow curve peaked at 145 deg. C. The 500 μm, which was a free standing sample, exhibited higher intensity and a well defined first order kinetics TL glow peak around 289 deg. C. Both diamond samples showed a linear dose behavior in the 1-50 Gy range and sublinear behavior for higher doses. The 180 and 500 μm samples presented about 80% and 30% TL losses in a 24 h period, respectively, with both samples showing excellent TL reproducibility. The results indicate that the 500 μm CVD diamond film exhibited a good TL behavior adequate for γ radiation dosimetry

  17. Thermal quenching of thermoluminescence in quartz samples of various origin

    International Nuclear Information System (INIS)

    Subedi, B.; Oniya, E.; Polymeris, G.S.; Afouxenidis, D.; Tsirliganis, N.C.; Kitis, G.

    2011-01-01

    The effect of thermal quenching stands among the most important properties in the thermoluminescence (TL) of quartz on which many applications of TL are based. Since the quartz samples used in various applications are all of different origin it is useful to investigate whether the values of the thermal quenching parameters, i.e. the activation energy for thermal quenching W and a parameter C which describes the ratio of non-radiative to radiative luminescence transitions, evaluated mainly in specific quartz samples can be extrapolated to quartz samples of unknown origin as well as to quartz samples which are annealed at high temperatures. In the present work the TL glow curve of a series of un-annealed and annealed natural and synthetic quartz samples were studied as a function of the heating rate between 0.25 K/s and 16 K/s. Using an indirect fitting method it was found that the thermal quenching parameters W and C in most of the quartz samples are very similar to the values accepted in the literature. Furthermore, in some cases the thermal quenching parameters W and C are not the same for all TL glow-peaks in the same glow-curve. Finally, the strong external treatment of annealing the quartz samples at very high temperature can also influence at least one of the thermal quenching parameters.

  18. About the measurements systems with pen and thermoluminescent dosemeters

    International Nuclear Information System (INIS)

    Cortes I, M.E.; Ramirez G, F.P.

    1998-01-01

    In this work it is presented dosimetric data obtained with pen and thermoluminescent dosemeters, which are used by the Occupational Exposure Personnel (OEP) of the Mexican Petroleum Institute (IMP)(1). It was marked several great characteristics as for example, the differences among units which use one and another dosemeter type. Likewise, it is given to know diverse problems that were had in the IMP at relating the data obtained with these dosemeters (which utilizes OEP) and the ICRP 60 recommendations 1990. One of the most important difficulties is to satisfy the recommended limits by ICRP, particularly those that are referring to the units and their complex calculations. With respect to the unities, the ICRP makes reference at the concepts 'dose equivalent' and 'effective dose' with the sievert unit, that the General Regulations for Radiological Safety associates with 'dose equivalent' and 'effective dose equivalent'. It was illustrated the type of dosimetric statistics which are obtained with the TLD lectures and a OEP pen dosemeter during 1997. (Author)

  19. Dose measurements in intraoral radiography using thermoluminescent dosimeters

    Science.gov (United States)

    Azorín, C.; Azorín, J.; Aguirre, F.; Rivera, T.

    2015-01-01

    The use of X-ray in medicine demands to expose the patient and the professional to the lowest radiation doses available in agreement with ALARA philosophy. The reference level for intraoral dental radiography is 7 mGy and, in Mexico, a number of examinations of this type are performed annually. It is considered that approximately 25% of all the X-rays examinations carried out in our country correspond to intraoral radiographies. In other hand, most of the intraoral X-ray equipment correspond to conventional radiological systems using film, which are developed as much manual as automatically. In this work the results of determining the doses received by the patients in intraoral radiological examinations made with different radiological systems using LiF:Mg,Cu,P+PTFE thermoluminescent dosimeters are presented. In some conventional radiological systems using film, when films are developed manual or automatically, incident kerma up to 10.61 ± 0.74 mGv were determined. These values exceed that reference level suggested by the IAEA and in the Mexican standards for intraoral examinations.

  20. Dose measurements in intraoral radiography using thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    Azorín, C; Rivera, T; Azorín, J; Aguirre, F

    2015-01-01

    The use of X-ray in medicine demands to expose the patient and the professional to the lowest radiation doses available in agreement with ALARA philosophy. The reference level for intraoral dental radiography is 7 mGy and, in Mexico, a number of examinations of this type are performed annually. It is considered that approximately 25% of all the X-rays examinations carried out in our country correspond to intraoral radiographies. In other hand, most of the intraoral X-ray equipment correspond to conventional radiological systems using film, which are developed as much manual as automatically. In this work the results of determining the doses received by the patients in intraoral radiological examinations made with different radiological systems using LiF:Mg,Cu,P+PTFE thermoluminescent dosimeters are presented. In some conventional radiological systems using film, when films are developed manual or automatically, incident kerma up to 10.61 ± 0.74 mGv were determined. These values exceed that reference level suggested by the IAEA and in the Mexican standards for intraoral examinations