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Sample records for cf am-be source

  1. New source moderator geometry to improve performance of 252Cf and 241Am Be source-based PGNAA setups

    Science.gov (United States)

    Naqvi, A. A.; Abdelmonem, M. S.; Al-Misned, Ghada; Al-Ghamdi, Hanan

    2006-06-01

    The gamma ray yield from a 252Cf and a 241Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the 252Cf and the 241Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a 252Cf and a 241Am-Be source-based PGNAA setups.

  2. Determining the neutron spectrum of 241Am-Be and 252Cf sources using bonner sphere spectrometer

    Directory of Open Access Journals (Sweden)

    M.A Varshabi

    2016-06-01

    Full Text Available Bonner spheres system is one of the ways of measuring neutron energy distribution which is often applied in spectrometry and neutron dosimetry. This system includes a thermal neutron detector, being located in the center of several polyethylene spheres, and it is still workable due to the isotropic response of the system which in turn is derived from the spherical symmetry of moderators and the broad measurable range of the energy. In order to practically use this spectrometer, it is necessary to calibrate this system using standard neutron sources. This research aimed to determine the calibration factor of Bonner spheres spectrometry system and energy spectrum of two standard 241Am-Be and 252Cf sources in the atomic energy organization. Calibration and experimental measurement were done via the two standard sources. The response vector of each detector was derived by using MCNPX simulation code, based on the Monte Carlo method. The spectra unfolding of this system was performed through iterative method using the SPUNIT code done in software NSDUAZ6LiI and BUMS. 

  3. New source-moderator geometry to improve performance of 252Cf and 241Am-Be source-based PGNAA setups

    International Nuclear Information System (INIS)

    The gamma ray yield from a 252Cf and a 241Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the 252Cf and the 241Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a 252Cf and a 241Am-Be source-based PGNAA setups

  4. New source-moderator geometry to improve performance of {sup 252}Cf and {sup 241}Am-Be source-based PGNAA setups

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)]. E-mail: aanaqvi@kfupm.edu.sa; Abdelmonem, M.S. [Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Misned, Ghada [Girls Education College, Riyadh Girls Colleges, Riyadh (Saudi Arabia); Al-Ghamdi, Hanan [Girls Education College, Riyadh Girls Colleges, Riyadh (Saudi Arabia)

    2006-06-15

    The gamma ray yield from a {sup 252}Cf and a {sup 241}Am-Be source-based Prompt Gamma Ray Activation Analysis (PGNAA) setup has been observed to increase with enclosing their neutrons sources in a high-density polyethylene moderator. The prompt gamma rays yield from both setups depends upon the moderator length and the source position in it. For both setups, the optimum moderator length is found to be 7 cm. The optimum position of the neutron source inside moderator of the {sup 252}Cf and the {sup 241}Am-Be source-based PGNAA setups was found to be at a distance of 0.5 and 0.75 cm from the moderator-end facing the sample, respectively. Due to enclosure of the source in the moderator, about three-fold increase has been observed in the yield of prompt gamma rays from a Portland cement sample of a {sup 252}Cf and a {sup 241}Am-Be source-based PGNAA setups.

  5. Measuring neutron energy spectra of 252Cf and Am-Be source with neutron time-of-flight spectrometer with double scintillators

    International Nuclear Information System (INIS)

    We established a neutron time-of-flight spectrometer with double scintillators. It can be used to measure the energy spectra of neutron sources. It is capable of working at above several hundred keV. We measured the energy spectra of 252Cf and Am-Be neutron sources by using this spectrometer. The results obtained were compared to those in other works

  6. On replacing Am-Be neutron sources in compensated porosity logging tools

    International Nuclear Information System (INIS)

    Full text: The authors are investigating potential replacements for the Americium-Beryllium (Am-Be) neutron source that has been used in neutron porosity logs. Am-Be sources are hazardous and would, therefore, be attractive to terrorists attempting to construct and use radiological dispersal devices (RDDs). This aspect of Am-Be sources makes them undesirable for industrial uses like well logging and in time may increase the difficulties in obtaining licenses for them. There has recently been a National Academy of Sciences Committee commissioned by Congress to author a report on Radiation Source Use and Replacement. This report is expected to be released very soon. There has also been a recent shift in the supplier of these sources to Russia, which represents possible problems in both supply and cost. These concerns led us to initiate the present study on possible replacements for the existing technology of using Am-Be sources in compensated porosity logs. Monte Carlo radiation transport simulations have been conducted with MCNP5 to investigate the responses of a typical wireline compensated neutron porosity logging tool. These results were compared to simulations where the Am-Be source was replaced with a 252Cf spontaneous fission neutron source and a deuterium-tritium fusion-based accelerator neutron source. The average energy of the 252Cf sources is about 2.1 MeV while that from an Am-Be source is about 4.2 MeV. However, the average neutron energy is not the entire story since a range of energies is involved with both the 252Cf and Am-Be sources. We are trying to investigate this problem from a fundamental point of view with the objective of understanding the phenomena underlying the compensated neutron porosity log. Both of these alternative sources would represent significantly reduced hazards in the possible terrorist purpose. A novel method involving the segmenting of the detectors used in the MCNP5 code has been developed to optimize detector spacing for the

  7. Recovery of 241Am/Be neutron sources, Wooster, Ohio

    International Nuclear Information System (INIS)

    In August 1997, the Nuclear Regulatory Commission (NRC) submitted to the US Department of Energy (DOE) a partial list of licensed radioactive sealed sources to be recovered under a pilot project initiating Radioactive Source Recovery Program (RSRP) operations. The first of the pilot project recoveries was scheduled for September 1997 at Eastern Well Surveys in Wooster, Ohio, a company with five unwanted sealed sources on the NRC list. The sources were neutron emitters, each containing 241Am/Be with activities ranging from 2.49 to 3.0 Ci. A prior radiological survey had established that one of these sources, a Gulf Nuclear Model 71-1 containing 3 Ci of 241Am, was contaminated with 241Am and might be leaking. The other four sources were obsolete and could no longer be used by Eastern Well Surveys for their intended application in well-logging applications due to NRC decertification of these sources. All of the sources exceeded the limits established for Class C waste under 10 CFR 61.55 and, as a result, are the ultimate responsibility of the DOE under the provisions of PL 99-240. This report describes the cooperative effort between the DOE and NRC to recover the sources and transport them to Los Alamos National Laboratory (LANL) for deactivation under the RSRP. This operation alleviated any potential risk to the public health and safety from the site which might result from the leaking neutron sources or the potential mismanagement of unwanted sources. The on-site recovery occurred on September 23, 1997, and was performed by personnel from LANL and its contractor and was observed by staff from the Region III office of the NRC. All aspects of the recovery were successfully accomplished, and the sources were received at LANL on September 29, 1997. Experience gained during this operation will be used to formulate operational poilicies and procedures which will contribute to the eventual routine recovery operations of a full-scale RSRP

  8. Calculation of anisotropy factors for 241Am-Be neutron sources

    International Nuclear Information System (INIS)

    The authors calculated anisotropy factors for 241Am-Be neutron sources used for calibration of neutron-measuring devices for radiation protection purpose. In this calculation, we created a calculation model composed of following three steps: (1) calculation of α-particle spectrum at the surface of spherical cluster of AmO2, (2) calculation of neutron yield in a thick beryllium target and of neutron spectrum produced by 8Be (α,n) reactions; and (3) calculation of angular fluence distribution of neutrons emerging from two different encapsulation types of 241Am-Be neutron sources. This computation was made by combining an in-house code using the 9Be(α,n) cross section data library (JENDL/AN-2005) and the Monte Carlo code MCNP-4C. As a result, anisotropy factors in the direction perpendicular to the source capsule axis were evaluated to be 1.030 and 1.039 for 241Am-Be in a standard Amersham X3 capsule and X4 capsule, respectively. These values are in reasonable close agreement with the published experimental data. If the support structures are included in the simulation, the anisotropy factors for these neutron sources increase by about 10%. (author)

  9. Detection limits of pollutants in water for PGNAA using Am Be source

    Science.gov (United States)

    Khelifi, R.; Amokrane, A.; Bode, P.

    2007-09-01

    A basic PGNAA facility with an Am-Be neutron source is described to analyze the pollutants in water. The properties of neutron flux were determined by MCNP calculations. In order to determine the efficiency curve of a HPGe detector, the prompt-gamma rays from chlorine were used and an exponential curve was fitted. The detection limits for typical water sample are also estimated using the statistical fluctuations of the background level in the areas of recorded the prompt-gamma spectrum.

  10. Detection limits of pollutants in water for PGNAA using Am-Be source

    Energy Technology Data Exchange (ETDEWEB)

    Khelifi, R. [Departement de Physique, Universite Saad Dahlab, BP: 270, Blida (Algeria)], E-mail: r_khelifi@yahoo.com; Amokrane, A. [Faculte de Physique, USTHB, Bab Ezzouar, Alger (Algeria); Bode, P. [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB (Netherlands)

    2007-09-15

    A basic PGNAA facility with an Am-Be neutron source is described to analyze the pollutants in water. The properties of neutron flux were determined by MCNP calculations. In order to determine the efficiency curve of a HPGe detector, the prompt-gamma rays from chlorine were used and an exponential curve was fitted. The detection limits for typical water sample are also estimated using the statistical fluctuations of the background level in the areas of recorded the prompt-gamma spectrum.

  11. Measurement of partial neutron spectrum of an Am-Be (α,n) source

    International Nuclear Information System (INIS)

    A partial neutron spectrum from an Am-Be (α,n) source has been measured by TOF accompanied with γ-ray. In the experiment the 4.43 MeV γ-ray comes from the reaction of 9Be(α,n)13Csup(*) (13Csup(*)(61fs)→12C+n+γ(4.43 MeV)). The result has been compared with others. (author)

  12. The investigation of Am-Be neutron source shield effect used on landmine detection

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei Ochbelagh, D. [Department of Physics, Faculty of Sciences, University of Mohagheg Ardebily, P.O. Box 179, Ardebil (Iran, Islamic Republic of)]. E-mail: ddrezaey@yahoo.com; Miri Hakimabad, H. [Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Najafabadi, R. Izadi [Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2007-07-11

    In this work, experiments were carried out to investigate the possible use of neutron backscattering for the detection of sample buried in the soil. A series of Monte Carlo simulations were performed to study the complexity of the neutron backscattering process and to optimize the source shield thickness. The results of these simulations indicate that neutron source shield plays an important role for the detection of nonmetallic landmines. This paper experimentally demonstrates, by using suitable shield around Am-Be neutron source, the increase of signal-to-noise ratio up to 130%.

  13. Neutron beam preparation with Am-Be source for analysis of biological samples with PGNAA method

    International Nuclear Information System (INIS)

    Material analysis with prompt gamma neutron activation analysis (PGNAA) requires a proper geometrical arrangement for equipments in laboratory. Application of PGNAA in analysis of biological samples, due to small size of sample, needs attention to the dimension of neutron beam. In our work, neutron source has been made of 241Am-Be type. Activity of 241Am was 20 Ci which lead to neutron source strength of 4.4 x 107 neutrons per second. Water has been considered as the basic shielding material for the neutron source. The effect of various concentration of boric acid in the reduction of intensity of fast and thermal components of the neutron beam and gamma ray has been investigated. Gamma ray is produced by (α, n) reaction in Am-Be source (4.483 MeV), neutron capture by hydrogen (2.224 MeV), and neutron capture by boron (0.483 MeV). Various types of neutron and gamma ray dosimeters have been employed including BF3 and NE-213 detectors to detect fast and thermal neutrons. BGO scintillation detector has been used for gamma ray spectroscopy. It is shown that the gamma and neutron radiation dose due to direct beam is of the same magnitude as the dose due to radiation scattered in the laboratory ambient. It is concluded that 14 kg boric acid dissolved in 1,000 kg water is the optimum solution to surround the neutron source. The experimental results have been compared with Monte Carlo simulation. (author)

  14. Neutron monitor calibration with 241AmBe(α, n), 252Cf , 252Cf+D2O and 238PuBe(α, n) used in dose evaluation near Linac

    International Nuclear Information System (INIS)

    The use of linear accelerators in Radiotherapy is becoming increasingly more common. From the Radiation Protection point of view, these instruments represent an advance relative to cobalt and caesium irradiators, mainly due to the absence of radioactive material. On the other hand, accelerators with energies over 10 MeV contaminate with neutrons the therapeutic beam. These neutrons are generated when high-energy photons interact with high-atomic-number materials such as tungsten and lead present in the accelerator itself. Photo-neutrons can also interact with other materials, present in the treatment room, consequently modifying the initial spectrum and causing other types of interactions which privilege the gamma capture. In this way, the measurement of the photo-neutron spectrum can be necessary in a radiometric survey. The present work carries through measurements in a linear accelerator of 15 MeV using three neutron area monitors calibrated using four radioactive sources: three ISO reference sources, 241AmBe (α, n), 252Cf (f, n) and 252Cf+D2O, and a 238PuBe(α, n) source. As the three first sources, this last one was standardized in the LMNRI/IRD manganese bath system. Comparison and evaluation of the response of these instruments were thereby made, analyzing whether the reading of the detectors using standard sources is adequate. In conclusion, the analysis of the response of neutron area calibrated detectors enable the use of them in an environment containing medical linear accelerator. (author)

  15. Development Of K0-INAA Standardization Method By Neutron Activation With Am-Be Source

    International Nuclear Information System (INIS)

    Method of k0 standardization in neutron activation analysis with Am-Be neutron source at DNP, University of Sciences, VNU-HCMC, have been researched and developed. In this paper, the parameters of neutron spectrum of Am-Be source such as epithermal neutron spectrum deviation (α), cadmium ratio (RCd) and ratio of fluxes of thermal/epithermal neutron (f) at thermal neutron irradiation position were measured by cadmium ratio method with dual monitors as Au and Mo, which actual were α = 0.075 ± 0.011, f 25.73 ± 2.20 and RCd,Au = 2.95 ± 0.12. HPGe detector efficiency curves for samples of cylinder and foil geometries were experimentally determined by home-made production of radioisotope 116mIn through neutron irradiation of 115In(n, γ)116mIn reaction. Application of k0 standardization method to concentration analytic of elements such as Al, Mn and Na in cement samples were carried out as well. Obtained elements concentration in this research was fairly agreed with other analyses. (author)

  16. Preliminary experiment of the controllable Am-Be neutron source based on composite polymeric membrane

    International Nuclear Information System (INIS)

    A controllable Am-Be neutron source was designed based on a hamburger structure including two Be pallets and a composite polymeric membrane carrying 241Am. The composite polymeric membrane was made of polyvinylidene fluoride (PVDF) and polyvinyl alcohol (PVA). PVDF polymeric membrane was used as the base film to load the mixed Am(NO3)3-PVA solution, which was coated on the PVDF polymeric membrane. The thickness of two layers was both about 5 μm. The correlative calculations were performed using the Geant4 code. A piece of composite membrane loading 241Am of 2.13 × 106 Bq was placed in the middle of two Be pallets just like a hamburger. Neutrons were produced continuously until the composite membrane was separated from Be pallets. The neutron yield of the controllable hamburger neutron source was measured as 54 n/(106α), which was 15.6 % lower than the calculation value. (author)

  17. Progress in Development of Dense Plasma Focus Pinch for AmBe Radiological Source Replacement

    Science.gov (United States)

    Falabella, Steve; Povilus, Alex; Schmidt, Andrea; Ellsworth, Jennifer; Link, Anthony; Sears, Jason; Higginson, Drew; Jiang, Sheng

    2015-11-01

    A dense plasma focus (DPF) is a compact plasma gun accelerator that can produce intense, high energy ion beams (multiple MeV). These ion beams could be used to replace radiological sources for a variety of applications. Using a 2kJ DPF with a helium gas fill, alpha particles are accelerated into a beryllium target in order to generate a neutron spectrum similar to an AmBe source. We report on initial observations of neutron yields for this system and efforts to optimize and improve repeatability of pinch performance. In particular, incorporating results from newly-developed kinetic LSP simulations, we demonstrated higher neutron yields by adjusting the geometry of the anode electrode. In addition, we present preliminary measurements for energy distributions of ions accelerated by the pinch. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work supported by US DOE/NA-22 Office of Non-proliferation Research and Development.

  18. 50 curie Am-Be neutron source in determining impurities in various materials

    International Nuclear Information System (INIS)

    The neutrons from a 50 Curies Am-Be neutron source after being thermalized have been used to study the impurities in various materials by measuring the gamma rays emitted from the activated samples. To get good resolution two HPGe detectors, one of them suitable for low energy gamma rays as well as X-rays and the other suitable for measuring the gamma-ray energies up to 10 MeV have been used. The resolution of the detectors were measured and proved to be better than 1.8 keV for 60Co gamma rays. During the measurements the detectors were placed in thick lead chambers. In these chambers the background was reduced dramatically. To make the whole system safe and also for saving time in activation analysis a fully computerized control rabbit device has been coupled to the system. Our main purpose is to set up a portable, cheap and reliable system for activation analysis for research institutions that are not able to have reactors due to various reasons. Although our tests and analysis is still in progress we think that the system is very promising. In this paper we will discuss about the details and the future prospects. (author)

  19. Collimator duct for neutron radiographs using a source of 241Am-Be

    International Nuclear Information System (INIS)

    With the aim of designing a collimator system to realize Neutron Radiographs using source of 241Am-Be, a collimator was designed using two removable modules. One parameter of merit to be considered in the building of a collimator is the intensity of the neutron beam on the image plane. Therefore, the choice of the inner coating material is of utmost importance. As the scattered neutrons can reduce the resolution of the neutron radiographic image, it would be opportune to capture them so that the neutron beam is aligned. Thus, an aligning module made of an absorbent material was designed, to coat the wall end extensions of the collimator. Two other parameters are essential to configure a collimator system: the length, L, and diameter of the opening, D. Geometric resolution of the neutron radiographic image is defined by the ratio L/D, as well as the neutron flux on the image plane. Simulations with code MCNP-4B were conducted to select the geometry of the collimator, the materials for the structure and coating and the dimensions for the L and D parameters and aluminum was chosen as the structural material and cadmium for coating. (author)

  20. The k0-NAA Standardization Method Using an Am-Be Neutron Source

    International Nuclear Information System (INIS)

    Instrumental neutron activation analysis is a well established technique for the analysis of trace elements in different samples. Precise elemental concentrations of Al, Mn, Mg and Na in two unknown geological samples were determined by using the k0-standardization method. For such measurements two sets of standard monitors of Gold (Au), Indium (In), Tungsten (W) and Titanium (Ta) were used. One set is bare and the other is cadmium covered. These monitors were used for measuring the irradiation position factors f and α and using the cadmium ratios of the 115In(n,γ)116In and 182Ta(n,γ)183Ta interactions. Neutrons were obtained from CNIF2 facility that uses an Am-Be radio-isotopic neutron source with a modification to have thermal and epi-thermal neutrons. Measurements were carried out using a gamma-ray spectrometer consisting of a hyper pure germanium detector and necessary associated electronics. The k0-standardization method can be used for quality control tests.

  1. Performance comparison of an 241Am-Be neutron source-based PGNAA setup with the KFUPM PGNAA setup

    International Nuclear Information System (INIS)

    Monte Carlo calculations have been carried out to compare the performance of an 241Am-Be neutron source-based prompt gamma neutron activation analysis (PGNAA) setup with that of the 2.8 MeV neutron-based PGNAA setup at King Fahd University of Petroleum and Minerals (KFUPM) to analyze Portland cement samples. This work is a part of a wide Monte Carlo studies being conducted at KFUPM in search of a more efficient neutron source for its 2.8 MeV neutrons, from the D(d,n) reaction, based PGNAA facility. In this study an 241Am-Be neutron source-based PGNAA setup was simulated. For comparison, the diameter of a cylindrical external moderator of the 241Am-Be neutron source, based PGNAA setup, was assumed to be similar to that used in the KFUPM PGNAA setup. It was revealed that although the optimum geometry of the 241Am-Be neutron source-based setup is similar to that of the KFUPM PGNAA facility, the performance of the 241Am-Be neutron source-based setup is slightly poorer than that of the 2.8 MeV neutron-based setup. (author)

  2. Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

    International Nuclear Information System (INIS)

    We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV γ-rays from a 137Cs source. The measured results on pulse shape discrimination (PSD) between nuclear- and electron-recoil events are quantified in terms of quality factors. A comparison with our previous result from a neutron generator demonstrate the feasibility of performing calibrations of PSD measurements using neutrons from a Am-Be source

  3. Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

    CERN Document Server

    Lee, H S; Choi, J H; Choi, S; Hahn, I S; Jeon, E J; Joo, H W; Kang, W G; Kim, G B; Kim, H J; Kim, K W; Kim, S C; Kim, S K; Kim, Y D; Kim, Y H; Lee, J H; Lee, J K; Leonard, D S; Li, J; Myung, S S; Olsen, S L; So, J H

    2014-01-01

    We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV $\\gamma$-rays from a $^{137}$Cs source. The measured results on pulse shape discrimination (PSD) between nuclear- and electron-recoil events are quantified in terms of quality factors. A comparison with similar result from a neutron reactor demonstrate the feasibility of performing calibrations of PSD measurements using neutrons from a Am-Be source.

  4. Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

    OpenAIRE

    Lee, H. S.; Bhang, H.; Choi, J.H.; Choi, S.; Hahn, I. S.; Jeon, E. J.; Joo, H. W.; Kang, W. G.; Kim, G. B.; Kim, H. J.; Kim, K. W.; Kim, S.C.; Kim, S K; Kim, Y.D.(Center for Underground Physics, Institute for Basic Science (IBS), Daejon, 305-811, Korea); Kim, Y H

    2014-01-01

    We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV $\\gamma$-rays from a $^{137}$Cs source. The measured results on pulse shape discrimination (PSD) be...

  5. Characterization of the neutron field from the 241Am-Be isotopic source of the IPHC irradiator

    International Nuclear Information System (INIS)

    A measurement campaign has been carried out recently to provide the source intensity and the reference spectra around a neutron irradiation facility based on 241Am-Be radionuclide source, using the UAB Bonner Sphere Spectrometer. This facility, which consists of a bunker, a container/shielding for the source and an irradiation device that uses an automated remote-controlled system for the source positioning and rotating during the dosimeter irradiation, is intended to be routinely used to check the response of passive dosimeters, namely those based on photo-stimulated imaging plates and solid-state nuclear track detectors. The measurement results, in terms of neutron spectra and global dosimetric quantities (i.e., fluence and ambient dose equivalent rates) at different distances with respect to the 241Am-Be source, were compared with Monte Carlo simulations using the MCNPX code and a good agreement was observed. An estimation of the un-scattered neutron spectrum directly emitted from the 241Am-Be source is given as well. - Highlights: ► We describe a neutron irradiation facility based on 241Am-Be radioactive source. ► The neutron field was characterized with a Bonner sphere spectrometer (BSS). ► Monte Carlo simulations using the MCNPX code were in good agreement with BSS. ► The un-scattered neutron spectrum is provided and compared to that given by the ISO-8529 standard. ► The neutron intensity of the 241Am-Be source is also estimated

  6. A quantitative PGNAA study for use in aqueous solution measurements using Am-Be neutron source and BGO scintillation detector

    Science.gov (United States)

    Ghal-Eh, N.; Ahmadi, P.; Doost-Mohammadi, V.

    2016-02-01

    A prompt gamma neutron activation analysis (PGNAA) system including an Am-Be neutron source and BGO scintillation detector are used for quantitative analysis of bulk samples. Both Monte Carlo-simulated and experimental data are considered as input data libraries for two different procedures based on neural network and least squares methods. The results confirm the feasibility and precision of the proposed methods.

  7. Characterization of a Sealed Americium-Beryllium (AmBe) Source by Inductively Coupled Plasma Mass Spectrometry

    International Nuclear Information System (INIS)

    Two Americium-Beryllium neutron sources were dismantled, sampled (sub-sampled) and analyzed via inductively coupled plasma mass spectrometry (ICP-MS). Characteristics such as 'age' since purification, actinide content, trace metal content and inter and intra source composition were determined. The 'age' since purification of the two sources was determined to be 25.0 and 25.4 years, respectively. The systematic errors in the 'age' determination were ± 4 % 2s. The amount and isotopic composition of U and Pu varied substantially between the sub-samples of Source 2 (n=8). This may be due to the physical means of sub-sampling or the way the source was manufactured. Source 1 was much more consistent in terms of content and isotopic composition (n=3 sub-samples). The Be-Am ratio varied greatly between the two sources. Source 1 had an Am-Be ratio of 6.3 ± 52 % (1s). Source 2 had an Am-Be ratio of 9.81 ± 3.5 % (1s). In addition, the trace element content between the samples varied greatly. Significant differences were determined between Source 1 and 2 for Sc, Sr, Y, Zr, Mo, Ba and W.

  8. Graphite moderated (252)Cf source.

    Science.gov (United States)

    Sajo-Bohus, Laszlo; Barros, Haydn; Greaves, Eduardo D; Vega-Carrillo, Hector Rene

    2015-06-01

    The Thorium molten-salt reactor is an attractive and affordable nuclear power option for developing countries with insufficient infrastructure and limited technological capability. In the aim of personnel training and experience gathering at the Universidad Simon Bolivar there is in progress a project of developing a subcritical thorium liquid-fuel reactor. The neutron source to run this subcritical reactor is a (252)Cf source and the reactor will use high-purity graphite as moderator. Using the MCNP5 code the neutron spectra of the (252)Cf in the center of the graphite moderator has been estimated along the channel where the liquid thorium salt will be inserted; also the ambient dose equivalent due to the source has been determined around the moderator. PMID:25770393

  9. Graphite moderated 252Cf source

    International Nuclear Information System (INIS)

    The thorium molten salt reactor is an attractive and affordable nuclear power option for developing countries with insufficient infrastructure and limited technological capability. In the aim of personnel training and experience gathering at the Universidad Simon Bolivar there is in progress a project of developing a subcritical thorium liquid fuel reactor. The neutron source to run this subcritical reactor is a 252Cf source and the reactor will use high-purity graphite as moderator. Using the MCNP5 code the neutron spectra of the 252Cf in the center of the graphite moderator has been estimated along the channel where the liquid thorium salt will be inserted; also the ambient dose equivalent due to the source has been determined around the moderator. (Author)

  10. Experimental Dating of 252Cf Sources

    International Nuclear Information System (INIS)

    The gamma spectrum of a 252Cf neutron source holds a large number of peaks from the FP, their products and other Cf isotopes present in the spectrum. The differences between a new and an old 252Cf neutron source gamma spectrum are mainly in the size of 661, 388 and 177 keV peaks from 137Cs, 249Cf and 251Cf, respectively

  11. Determination of boron in water solution by an indirect neutron activation technique from a 241Am/Be source

    International Nuclear Information System (INIS)

    Boron content in water solutions has been analysed by Indirect Activation Technique a twin 241Am/Be neutron source with a source strength of 9x106 n/seg. The boron concentration was inferred from the measurement of the activity induced in a vanadium flux monitor. The vanadium rod was located inside the boron solution in a standart geometrical set up with respect to the neutron source. Boron concentrations in the range of 100 to 1000 ppm were determined with an overall accuracy of about 2% during a total analysis time of about 20 minutes. Eventhough the analysis is not selective for boron yet due the rapid, simple and precise nature, it is proposed for the analysis of boron in the primary coolant circuit of Nuclear Power Plants of PWR type. (Author)

  12. Monte Carlo optimization of sample dimensions of an 241Am Be source-based PGNAA setup for water rejects analysis

    Science.gov (United States)

    Idiri, Z.; Mazrou, H.; Beddek, S.; Amokrane, A.; Azbouche, A.

    2007-07-01

    The present paper describes the optimization of sample dimensions of a 241Am-Be neutron source-based Prompt gamma neutron activation analysis (PGNAA) setup devoted for in situ environmental water rejects analysis. The optimal dimensions have been achieved following extensive Monte Carlo neutron flux calculations using MCNP5 computer code. A validation process has been performed for the proposed preliminary setup with measurements of thermal neutron flux by activation technique of indium foils, bare and with cadmium covered sheet. Sensitive calculations were subsequently performed to simulate real conditions of in situ analysis by determining thermal neutron flux perturbations in samples according to chlorine and organic matter concentrations changes. The desired optimal sample dimensions were finally achieved once established constraints regarding neutron damage to semi-conductor gamma detector, pulse pile-up, dead time and radiation hazards were fully met.

  13. Neutron monitor calibration with {sup 241}AmBe({alpha}, n), {sup 252}Cf , {sup 252C}f+D{sub 2}O and {sup 238}PuBe({alpha}, n) used in dose evaluation near Linac

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Ana Paula; Pereira, Walsan Wagner; Patrao, Karla Cristina de Souza; Fonseca, Evaldo Simoes da [Instituto de Radioprotecao e Dosimetria (IRD-CNEN/RJ), Rio de Janeiro, RJ (Brazil). Lab. de Neutrons], e-mail: asalgado@ird.gov.br

    2009-07-01

    The use of linear accelerators in Radiotherapy is becoming increasingly more common. From the Radiation Protection point of view, these instruments represent an advance relative to cobalt and caesium irradiators, mainly due to the absence of radioactive material. On the other hand, accelerators with energies over 10 MeV contaminate with neutrons the therapeutic beam. These neutrons are generated when high-energy photons interact with high-atomic-number materials such as tungsten and lead present in the accelerator itself. Photo-neutrons can also interact with other materials, present in the treatment room, consequently modifying the initial spectrum and causing other types of interactions which privilege the gamma capture. In this way, the measurement of the photo-neutron spectrum can be necessary in a radiometric survey. The present work carries through measurements in a linear accelerator of 15 MeV using three neutron area monitors calibrated using four radioactive sources: three ISO reference sources, {sup 241}AmBe ({alpha}, n), {sup 252}Cf (f, n) and 252{sup C}f+D{sub 2}O, and a 238{sup P}uBe({alpha}, n) source. As the three first sources, this last one was standardized in the LMNRI/IRD manganese bath system. Comparison and evaluation of the response of these instruments were thereby made, analyzing whether the reading of the detectors using standard sources is adequate. In conclusion, the analysis of the response of neutron area calibrated detectors enable the use of them in an environment containing medical linear accelerator. (a0011uth.

  14. Aluminium and copper analysis in metallic alloys by neutron activation analysis from an 241 Am-Be source

    International Nuclear Information System (INIS)

    Aluminium and copper have been determined in aluminium alloys by the method of activation with neutrons from an 241 Am-Be source of intensity 9,8 x 106 n/s. The activity induced due to reactions 27 Al (n, γ)28 Al and 63 Cu (n, γ)64 Cu have been measured with a NaI (Tl) detector coupled to a single channel system. In order to obtain the samples and standards of about the same composition, the material to be irradiated was powdered. In view of low intensity of neutron source it was necessary to use samples of up to 50 g. A series of preliminary irradiations were carried out to ensure that the geometry for the irradiation and for the counting are reproducible. The results have been compared with those obtained by chemical methods. Assuming that the results obtained by chemical method is exact, a maximum relative error of 3,6% is obtained by this method. The method has a good reproducibility. The time needed for analysis of aluminium and copper are 18 min and 2 hours 40 minutes respectively. Four different samples were analysed. The average of five measurements for one of the samples was: 88.0% for aluminium and 10.0% for copper. The standard deviation and coefficient of variation were 0,8 and 1.0% for aluminium and 0,2 and 2.0% for copper. (author)

  15. Recoiled Proton Track Registration in Polycarbonate Plastic by Irradiation of Neutron from 241Am-Be Radioisotope Source

    International Nuclear Information System (INIS)

    Full text: This research attempts to investigate properties of recoiled proton track registration in polycarbonate (PC) which was irradiated by neutrons from 241Am-Be source. The irradiated PC was etched with PEW solution (15% KOH, 45% H2O and 40% ethyl alcohol) at 70oC for 1 h. The recoiled proton tracks were observed under an optical microscope at approximately 100 times of magnification. The tracks were then characterized by using the Image J program which is an image processing and analysis software. The study showed that the average track density in PC was 2.74 x 105 tracks per square centimeter for a neutron flux of approximately 1.58 x 104neutrons/cm2.s at 2 weeks of irradiation time. The minimum and maximum track areas were found to be 3.443 and 340.698 μm2 while the minimum and maximum track diameters were found to be 4.137 and 20.828μm respectively

  16. Determination of vanadium, manganese and tungsten in steels with an 241 Am-Be isotopic neutron source

    International Nuclear Information System (INIS)

    A non-destructive neutron activation method was developed for determination of vanadium, manganese, and tungsten in alloy-steel, with the aid of an Am-Be 1,85x1011Bq(5Ci) isotopic neutron source, employing NaI (T1) detector well type 2x2 in. The 51V (n,γ) 52V, 55Mn (n,γ) 56Mn, and 186W (n,γ) 187W nuclear reactions are induced in steel samples subject to activation by thermal neutron. After irradiation, the activity of the samples was measured by γ-spectrometry under the 1434 KeV 52V, 847KeV 56Mn, and 686 KeV 187W photopeaks. Possible interferences due to other radionuclides activity were investigated by determining the 52V, 56Mn, and 187W half-lifes. The time of analysis for vanadium determination was 11 min, with 1,5% of precision and 3,4% of average absolute deviation. The time of analysis for manganese determination was 22,8 min with 4,0% of precision and 3,4% of average absolute deviation. The time of analysis for tungsten determination was 44,62 min with 3,8% of precision and 3,1% of average absolute deviation. The activation analysis method is adequated for steel quality control in industry. (Author)

  17. Characterization of neutron flux spectra in the irradiation sites of a 37 GBq {sup 241}Am-Be isotopic source

    Energy Technology Data Exchange (ETDEWEB)

    Yücel, Haluk [Ankara University, Institute of Nuclear Sciences, 06100 Tandogan, Ankara (Turkey); Budak, Mustafa Guray, E-mail: mbudak@gazi.edu.tr [Gazi University, Gazi Education Faculty, 06500 Teknikokullar, Ankara (Turkey); Karadag, Mustafa [Gazi University, Gazi Education Faculty, 06500 Teknikokullar, Ankara (Turkey); Yüksel, Alptuğ Özer [Ankara University, Institute of Nuclear Sciences, 06100 Tandogan, Ankara (Turkey)

    2014-11-01

    Highlights: • An irradiation unit was installed using a 37 GBq {sup 241}Am-Be neutron source. • The source neutrons moderated by using both water and paraffin. • Irradiation unit was shielded by boron oxide and lead against neutrons and gammas. • There are two sites for irradiations, one of them has a pneumatic transfer system. • Cadmium ratio method was used for irradiation site characterization. - Abstract: For the applicability of instrumental neutron activation analysis (NAA) technique, an irradiation unit with a 37 GBq {sup 241}Am-Be neutron source was installed at Institute of Nuclear Sciences of Ankara University. Design and configuration properties of the irradiation unit are described. It has two different sample irradiation positions, one is called site #1 having a pneumatic sample transfer system and the other is site #2 having a location for manual use. In order to characterize neutron flux spectra in the irradiation sites, the measurement results were obtained for thermal (φ{sub th}) and epithermal neutron fluxes (φ{sub epi}), thermal to epithermal flux ratio (f) and epithermal spectrum shaping factors (α) by employing cadmium ratios of gold (Au) and molybdenum (Mo) monitors. The activities produced in these foils were measured by using a p-type, 44.8% relative efficiency HPGe well detector. For the measured γ-rays, self-absorption and true coincidence summing effects were taken into account. Additionally, thermal neutron self-shielding and resonance neutron self-shielding effects were taken into account in the measured results. For characterization of site #1, the required parameters were found to be φ{sub th} = (2.11 ± 0.05) × 10{sup 3} n cm{sup −2} s{sup −1}, φ{sub epi} = (3.32 ± 0.17) × 10{sup 1} n cm{sup −2} s{sup −1}, f = 63.6 ± 1.5, α = 0.045 ± 0.009, respectively. Similarly, those parameters were measured in site #2 as φ{sub th} = (1.49 ± 0.04) × 10{sup 3} n cm{sup −2} s{sup −1}, φ{sub epi} = (2.93 ± 0

  18. Characterization of neutron flux spectra in the irradiation sites of a 37 GBq 241Am-Be isotopic source

    International Nuclear Information System (INIS)

    Highlights: • An irradiation unit was installed using a 37 GBq 241Am-Be neutron source. • The source neutrons moderated by using both water and paraffin. • Irradiation unit was shielded by boron oxide and lead against neutrons and gammas. • There are two sites for irradiations, one of them has a pneumatic transfer system. • Cadmium ratio method was used for irradiation site characterization. - Abstract: For the applicability of instrumental neutron activation analysis (NAA) technique, an irradiation unit with a 37 GBq 241Am-Be neutron source was installed at Institute of Nuclear Sciences of Ankara University. Design and configuration properties of the irradiation unit are described. It has two different sample irradiation positions, one is called site #1 having a pneumatic sample transfer system and the other is site #2 having a location for manual use. In order to characterize neutron flux spectra in the irradiation sites, the measurement results were obtained for thermal (φth) and epithermal neutron fluxes (φepi), thermal to epithermal flux ratio (f) and epithermal spectrum shaping factors (α) by employing cadmium ratios of gold (Au) and molybdenum (Mo) monitors. The activities produced in these foils were measured by using a p-type, 44.8% relative efficiency HPGe well detector. For the measured γ-rays, self-absorption and true coincidence summing effects were taken into account. Additionally, thermal neutron self-shielding and resonance neutron self-shielding effects were taken into account in the measured results. For characterization of site #1, the required parameters were found to be φth = (2.11 ± 0.05) × 103 n cm−2 s−1, φepi = (3.32 ± 0.17) × 101 n cm−2 s−1, f = 63.6 ± 1.5, α = 0.045 ± 0.009, respectively. Similarly, those parameters were measured in site #2 as φth = (1.49 ± 0.04) × 103 n cm−2 s−1, φepi = (2.93 ± 0.15) × 101 n cm−2 s−1, f = 50.9 ± 1.3 and α = 0.038 ± 0.008. The results for f-values indicate

  19. Prompt gamma-ray neutron activation analysis (PGNAA) system by using a 740 GBq 241Am-Be neutron source

    International Nuclear Information System (INIS)

    A PGNAA system consisting of a 740 GBq 241Am-Be neutron source and a gamma spectrometer with a n-type Ge (REGe) detector was installed at Ankara Nuclear Training and Research Center to measure the prompt gamma-rays produced by the interactions of thermal neutrons in the samples for the analysis of light elements such as B, P, S and Cl, and some trace elements with large cross sections (Cd, Hg, Sm, Gd, etc.). In the irradiation system, a 55 cm diameter cylinder tank filled with the water moderator comprises the neutron source placed in a polypropylene tube that was positioned in lead rings (internal diameter - 9 cm and outer diameter - 21 cm) in order to reduce the gamma rays emitted from the source such as 0.0596 MeV (241Am) and 4.43 MeV (0.6 gamma per neutron) from the 9Be(α, n) reaction in the source. The moderator tank was shielded with paraffin in all sides against fast neutrons. The thickness of paraffin at the front side of the tank is 28 cm and 18 cm at other sides. The neutron irradiation system was also shielded by using chevron lead bricks of 18 cm thickness. The background-prominent gamma-rays which is especially the 2.223 MeV gamma ray from the 1H(n, γ) reaction formed in hydrogenous materials used for neutron moderation was reduced remarkably in view of the permissible gamma dose for overall irradiation room. The neutrons thermalized in moderator travel through the hole with 6 cm diameter for the sample irradiation. The detector was shielded with Li2CO3 powder against thermal neutrons to avoid radiation damage and surrounded by additional lead bricks to reduce gamma-background. The measurements are carried out for efficiency calibration of the detector by using the standard source. The characteristics of PGNAA system with the isotopic neutron source and its analysis capability are discussed

  20. Radionuclide 252Cf neutron source

    International Nuclear Information System (INIS)

    Characteristics of radionuclide neutron sourses of 252Cf base with the activity from 106 to 109 n/s have been investigated. Energetic distributions of neutrons and gamma-radiation have been presented. The results obtained have been compared with other data available. The hardness parameter of the neutron spectrum for the energy range from 3 to 15 MeV is 1.4 +- 0.02 MeV

  1. NAA of copper in its ores by ''2''4''1Am-Be neutron source using the standard addition technique

    International Nuclear Information System (INIS)

    Neutron activation analysis using nuclear reactors as sources of activating particles is a well established technique, which has been described adequately in the literature and has been used for the analysis of a wide range of materials. The ''2''4''1Am-Be neutron source is also a useful source of activating particles for, although the neutron flux is relatively low (approximately 10''5 ncm''-''2 s''-''1) it is adequate for a range of analyses where extreme sensitivity is not of prime importance and offers the advantages of relatively low cost and ease of operation. The determination of Cu in its ores has been investigated for a typical industrial application of ''2''4''1Am-Be neutron activation by method of standard addition

  2. Assessment of the neutron emission anisotropy factor of a sealed AmBe source by means of measurements and Monte Carlo simulations

    International Nuclear Information System (INIS)

    The neutron emission anisotropy factor of a sealed Americium–Beryllium source is experimentally determined and compared to Monte Carlo simulations. The measurements were done at the Italian Institute for Metrology of Ionizing Radiations using a long counter neutron detector and a “X.3” type AmBe sealed neutron source. Experimental data are compared to simulations performed with the MCNP code where the precise structure of the source is taken into account starting from its technical design. The contributions of the single structural parts are described to point out the effective sources of the emission anisotropy

  3. Assessment of the neutron emission anisotropy factor of a sealed AmBe source by means of measurements and Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Loreti, S.; Pietropaolo, A., E-mail: antonino.pietropaolo@enea.it

    2015-10-11

    The neutron emission anisotropy factor of a sealed Americium–Beryllium source is experimentally determined and compared to Monte Carlo simulations. The measurements were done at the Italian Institute for Metrology of Ionizing Radiations using a long counter neutron detector and a “X.3” type AmBe sealed neutron source. Experimental data are compared to simulations performed with the MCNP code where the precise structure of the source is taken into account starting from its technical design. The contributions of the single structural parts are described to point out the effective sources of the emission anisotropy.

  4. Characterization of the CRNA Bonner sphere spectrometer based on {sup 6}LiI scintillator exposed to an {sup 241}Am-Be neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Mazrou, Hakim [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz Fanon, B.P. 399, 16000 Alger (Algeria)], E-mail: mazrou_h@comena-dz.org; Sidahmed, Tassadit; Idiri, Zahir; Lounis-Mokrani, Zohra; Bedek, Said [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz Fanon, B.P. 399, 16000 Alger (Algeria); Allab, Malika [Faculte de Physique, Universite des Sciences et de la Technologie Houari-Boumediene (USTHB), Alger (Algeria)

    2008-02-15

    In the present work, measurements have been performed using an available multisphere neutron spectrometer based on a calibrated {sup 6}LiI scintillation detector (10mmox2mm) exposed to an {sup 241}Am-Be neutron source. Sensitive analysis has been performed to assess influence of angle and source-detector distances dependence on the detector responses. Our experimental responses were compared with the published experimental and calculated data for two {sup 241}Am-Be (ISO, PTB) neutron spectra with (4mmox4mm) {sup 6}LiI detector. A discrepancy by a factor of about two was achieved and it is chiefly due to the difference shown in active surface of both detectors.

  5. Improving the performance of 241Am-Be for PGNAA applications using a proper shielding for neutron source and the NaI detector

    OpenAIRE

    Panjeh Hamed; Hakimabad Hashem M.; Motavalli Lalle R.

    2010-01-01

    The gamma ray spectrum resolution from a 241Am-Be source-based prompt gamma ray activation analysis set-up has been observed to increase in the energy region of interest with enclosing the NaI detector in a proper neutron and gamma ray shield. We have investigated the tact that the peak resolution of prompt gamma rays in the region of interest from the set-up depends on the source activity to the great extent, size and kind of the detector and the geometry of the detector shield. In ord...

  6. Graphite moderated {sup 252}Cf source

    Energy Technology Data Exchange (ETDEWEB)

    Sajo B, L.; Barros, H.; Greaves, E. D. [Universidad Simon Bolivar, Nuclear Physics Laboratory, Apdo. 89000, 1080A Caracas (Venezuela, Bolivarian Republic of); Vega C, H. R., E-mail: fermineutron@yahoo.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2014-08-15

    The thorium molten salt reactor is an attractive and affordable nuclear power option for developing countries with insufficient infrastructure and limited technological capability. In the aim of personnel training and experience gathering at the Universidad Simon Bolivar there is in progress a project of developing a subcritical thorium liquid fuel reactor. The neutron source to run this subcritical reactor is a {sup 252}Cf source and the reactor will use high-purity graphite as moderator. Using the MCNP5 code the neutron spectra of the {sup 252}Cf in the center of the graphite moderator has been estimated along the channel where the liquid thorium salt will be inserted; also the ambient dose equivalent due to the source has been determined around the moderator. (Author)

  7. International key comparison of measurements of neutron source emission rate (1999-2005): CCRI(III)-K9.AmBe

    International Nuclear Information System (INIS)

    Section III (neutron measurements) of the Comite Consultatif des Rayonnements Ionisants, CCRI, conducted a key comparison of primary measurements of the neutron emission rate of an 241Am-Be(α,n) radionuclide source. A single 241Am-Be(α,n) source was circulated to all the participants between 1999 and 2005. Eight laboratories participated - the CIAE (China), CMI (Czech Republic), KRISS (Republic of Korea), LNMRI (Brazil), LNE-LNHB (France), NIST (USA), NPL (UK) and the VNIIM (Russian Federation) - with the NPL making their measurements at the start and repeating them near the end of the exercise to verify the stability of the source. Each laboratory reported the emission rate into 4π sr together with a detailed uncertainty budget. All participants used the manganese bath technique, with the VNIIM also making measurements using an associated particle technique. The CMI, KRISS, VNIIM, and later the NPL, also measured the anisotropy of the source although this was not a formal part of the comparison. The first draft report was released in May 2006 and having been discussed and modified by the participants and subsequently reviewed by the CCRI(III), the present paper is now the final report of the comparison. (authors)

  8. MCNP simulation of the incident and Albedo neutron response of the IRD Albedo Neutron Dosemeter for 241Am-Be moderated sources

    International Nuclear Information System (INIS)

    The IRD TLD Albedo dosemeter measures both incident and albedo neutron component. The incident to Albedo ratio is used to take into account the energy dependence of its response. In this paper, the behavior of the IRD Albedo dosemeter response as a function of the incident to Albedo ratio for 241Am-Be sources was simulated to improve its algorithm. The simulation was performed in MCNPX transport code and presents a good agreement with experimental measurements. The results obtained in this work are very useful to improve the accuracy of the IRD Albedo dosemeter at real neutron workplace. (author)

  9. Material recognition with a 252Cf source

    CERN Document Server

    Fabris, Daniela; Lunardon, Marcello; Moretto, Sandra; Nebbia, Giancarlo; Pesente, Silvia; Stevanato , Luca; Viesti, Giuseppe; Sajo-Bohusb, Laszlo

    2010-01-01

    Material recognition is studied by measuring simultaneously the transmission of neutron and gamma rays produced by a time-tagged 252Cf source. Light elements (C,N,O) are identified by using the measured transmission versus neutron time of flight. The yield of the transmitted gamma ray as a function of energy provides high precision identification of the atomic number of the sample up to Z=83 . A tomography system, currently under construction, is described.

  10. Neutron shielding for a 252 Cf source

    International Nuclear Information System (INIS)

    To determine the neutron shielding features of water-extended polyester a Monte Carlo study was carried out. Materials with low atomic number are predominantly used for neutron shielding because these materials effectively attenuate neutrons, mainly through inelastic collisions and absorption reactions. During the selection of materials to design a neutron shield, prompt gamma production as well as radionuclide production induced by neutron activation must be considered. In this investigation the Monte Carlo method was used to evaluate the performance of a water-extended polyester shield designed for the transportation, storage, and use of a 252Cf isotopic neutron source. During calculations a detailed model for the 252Cf and the shield was utilized. To compare the shielding features of water extended polyester, the calculations were also made for the bare 252Cf in vacuum, air and the shield filled with water. For all cases the calculated neutron spectra was utilized to determine the ambient equivalent neutron dose at four sites around the shielding. In the case of water extended polyester and water shielding the calculations were extended to include the prompt gamma rays produced during neutron interactions, with this information the Kerma in air was calculated at the same locations where the ambient equivalent neutron dose was determined. (Author)

  11. Neutron sources of palladium-252Cf oxide cermet wire

    International Nuclear Information System (INIS)

    Palladium-252Cf oxide cermet has been developed as a versatile, safe source form for 252Cf with low contamination potential. Developmental wire containing 1.85 mg of 252Cf has been sold in three orders to U. S. commercial encapsulators. Bare palladium-252Cf oxide cermet wire containing 252Cf concentrations of 5, 50, or 500 μg/in. is expected to be offered for general sale in the near future. (U.S.)

  12. Monte Carlo optimization of sample dimensions of an {sup 241}Am-Be source-based PGNAA setup for water rejects analysis

    Energy Technology Data Exchange (ETDEWEB)

    Idiri, Z. [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz-Fanon, B.P. 399, 16000 Alger (Algeria)]. E-mail: zmidiri@yahoo.fr; Mazrou, H. [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz-Fanon, B.P. 399, 16000 Alger (Algeria); Beddek, S. [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz-Fanon, B.P. 399, 16000 Alger (Algeria); Amokrane, A. [Faculte de Physique, Universite des Sciences et de la Technologie Houari-Boumediene (USTHB), Alger (Algeria); Azbouche, A. [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz-Fanon, B.P. 399, 16000 Alger (Algeria)

    2007-07-21

    The present paper describes the optimization of sample dimensions of a {sup 241}Am-Be neutron source-based Prompt gamma neutron activation analysis (PGNAA) setup devoted for in situ environmental water rejects analysis. The optimal dimensions have been achieved following extensive Monte Carlo neutron flux calculations using MCNP5 computer code. A validation process has been performed for the proposed preliminary setup with measurements of thermal neutron flux by activation technique of indium foils, bare and with cadmium covered sheet. Sensitive calculations were subsequently performed to simulate real conditions of in situ analysis by determining thermal neutron flux perturbations in samples according to chlorine and organic matter concentrations changes. The desired optimal sample dimensions were finally achieved once established constraints regarding neutron damage to semi-conductor gamma detector, pulse pile-up, dead time and radiation hazards were fully met.

  13. Improving the performance of 241Am-Be for PGNAA applications using a proper shielding for neutron source and the NaI detector

    Directory of Open Access Journals (Sweden)

    Panjeh Hamed

    2010-01-01

    Full Text Available The gamma ray spectrum resolution from a 241Am-Be source-based prompt gamma ray activation analysis set-up has been observed to increase in the energy region of interest with enclosing the NaI detector in a proper neutron and gamma ray shield. We have investigated the tact that the peak resolution of prompt gamma rays in the region of interest from the set-up depends on the source activity to the great extent, size and kind of the detector and the geometry of the detector shield. In order to see the role of a detector shield, five kinds of the detector shield were used and finally the proper kind was introduced. Since the detector shield has an important contribution in the reduction of the undesirable and high rate gamma rays coming to the gamma ray detector, a good design of a proper shield enables the elimination of the unwanted events, such as a pulse pile-up. By improving the shielding design, discrete and distinguishable photoelectric peaks in the energy region of interest have been observed in the spectrum of prompt gamma rays.

  14. Development of a prompt-gamma neutron activation analysis facility for small animal in vivo body composition studies using Am-Be Source

    International Nuclear Information System (INIS)

    Full text: The design, calibration, radiation dosimetry and preliminary performance evaluation of a prompt-gamma neutron activation analysis facility for in vivo body composition studies in small animals (i.e. rats or rabbits) are described. The system design was guided by Monte Carlo neutron and photon transport calculations performed using the MCNP-4C code. The facility utilizes a 555 GBq (15 Ci) Am-Be radionuclide neutron source positioned within a graphite collimator and appropriate shielding assembly. Prompt gamma rays produced by thermal neutron capture reactions within the animal are detected by a combination of a NaI(Tl) and a HPGe detectors positioned on either side of the sample, perpendicularly to the neutron beam. Small animal body nitrogen and hydrogen are determined by the NaI(Tl) detector by analysis of the 10.83 MeV and 2.22 MeV peaks, respectively, while calcium and chlorine are determined by the HPGe detector by analysis of the 6.42 MeV and 6.11 MeV peaks, respectively. Moreover, body potassium is determined independently by means of 40K measurement at a modified whole body counter facility. Appropriate corrections for animal body size and shape are applied. Mixed neutron and gamma radiation dosimetry was performed using a tissue-equivalent proportional counter. The facility described is a simple tool enabling us to perform in vivo analysis of the major body compartments of protein, bone mass, extra-cellular and intra-cellular space. It will be used to perform serial nutritional and metabolic studies in sets of small experimental animals under controlled conditions for an ethically accepted radiation dose and without the need to kill the animal. (author)

  15. System control for the modulated 252Cf source ''Shuffler''

    International Nuclear Information System (INIS)

    The design and theory of operation of the control chassis for a 252Cf nondestructive assay system are described. This system repetitively transfers a 252Cf source from the irradiation region to a shielded position before measuring the delayed neutrons. The design criteria for the system were: rapid movement and precise positioning of the 252Cf source, precise positioning of the sample, and very accurate timing of the irradiate and count cycles. To achieve these results crystal oscillators were used for timing, and stepping motors were used to position the sample and the source. (U.S.)

  16. INAA using 252Cf neutron source at University of Pune

    International Nuclear Information System (INIS)

    The review presents the work done over last two decades on Instrumental Neutron Activation Analysis (INAA) by our research group at University of Pune using 252Cf spontaneous fission neutron source. The technique has been applied in different fields viz. numismatics, industry, agriculture, ayurveda, environmental and health sciences and diffusion studies. A brief discussion of the work is presented in this article. (author)

  17. Study of the geometrical configuration of a Set-Up for the purpose of analysing organic matter using neutron backscattering with an AM-BE source and a HE3 detector

    International Nuclear Information System (INIS)

    Neutron backscattering is a powerful technique to analyse organic matter and recently a set-up has been developed by our laboratory to determine bitumen content in asphalt concrete [1].This set-up is mainly composed of an Am-Be neutron source and a He-3 detector, the source being placed under the He-3 detector. In this work, we study two geometrical configurations, the first where the source is placed under the detector and the other one is when the source and the detector are side by side. The calibration curves for the determination of bitumen content in asphalt concrete, hydrogen and the ratio C/H are built for the two geometries and then compared in terms of sensitivity. Finally, some Algerian oil samples are analysed with these setups

  18. Determination of some elements using 252Cf source

    International Nuclear Information System (INIS)

    A description of determination of Al and Si in mountain rocks is given based on measurement of intensity of gamma-rays of 28Al (half-decay period 2.3 min) which is formed in reactions: 27Al(n,γ)28Al with thermal neutrons and 28Si(n,p)28Al (with fast neutrons). To activate samples, a 252Cf source has been used with a flux of (1.0+-0.1)x109 neutrons/sec. Induced gamma-radioactivity has been registered by an AI-128 analyser and NaI(Tl) sensor (40x40 mm) with a FEU-13 photo-electron multiplier and a cathode follower. The relative error of the method is 13% for Al and 18% for Si. The efficiency is 70 samples per day. Calculations have indicated that while using 252Cf it is possible to determine Na in rocks when its content is 10-4 g

  19. CF3CH(ONO)CF3: Synthesis, IR spectrum, and use as OH radical source for kinetic and mechanistic studies

    DEFF Research Database (Denmark)

    Andersen, Mads Peter Sulbæk; Hurley, MD; Ball, JC;

    2003-01-01

    The synthesis, IR spectrum, and first-principles characterization of CF3CH(ONO)CF3 as well as its use as an OH radical source in kinetic and mechanistic studies are reported. CF3CH(ONO)CF3 exists in two conformers corresponding to rotation about the RCO-NO bond. The more prevalent trans conformer...

  20. Personnel exposure experience related to use of 252Cf sources

    International Nuclear Information System (INIS)

    Studies are presented of personnel exposures to 252Cf neutrons and gamma radiation during dosimetry experiments in mouse phantoms, fission foil detectors, and small tissue equivalent ionization chambers. Sensitivity of film badge emulsions to observed levels of 252Cf neutrons is discussed. Long-term personnel exposure histories are presented. Comparisons are made between neutron dose calculated from observed neutron-gamma ratios and the dose observed in neutron emulsions. Shielding used during experiments is described

  1. Neutron Spectra, Fluence and Dose Rates from Bare and Moderated Cf-252 Sources

    Energy Technology Data Exchange (ETDEWEB)

    Radev, Radoslav P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-04-01

    A new, stronger 252Cf source (serial number SR-CF-3050-OR) was obtained from Oak Ridge National Laboratory (ORNL) in 2014 to supplement the existing 252Cf sources which had significantly decayed. A new instrument positioning track system was designed and installed by Hopewell Designs, Inc. in 2011. The neutron field from the new, stronger 252Cf source in the modified calibration environment needed to be characterized as well as the modified neutron fields produced by the new source and seven different neutron moderators. Comprehensive information about our 252Cf source, its origin, production, and isotopic content and decay characteristics needed to be compiled as well. This technical report is intended to address these issues.

  2. Development of high-activity 252Cf sources for neutron brachytherapy

    International Nuclear Information System (INIS)

    The Gershenson Radiation Oncology Center of Wayne State University (WSU), Detroit, Michigan, is using 252Cf medical sources for neutron brachytherapy. These sources are based on a 20-year-old design containing ≤ 30 microg 252Cf in the form of a cermet wire of Cf2O3 in a palladium matrix. The Radiochemical Engineering Development Center (REDC) of Oak Ridge National Laboratory has been asked to develop tiny high-activity 252Cf neutron sources for use with remote afterloading equipment to reduce treatment times and dose to clinical personnel and to expedite treatment of brain and other tumors. To date, the REDC has demonstrated that 252Cf loadings can be greatly increased in cermet wires much smaller than before. Equipment designed for hot cell fabrication of these wires is being tested. A parallel program is under way to relicense the existing source design for fabrication at the REDC

  3. Safety analysis of doubly encapsulated 252Cf medical sources, Model TALC-PC

    International Nuclear Information System (INIS)

    This document describes the doubly encapsulated 252Cf neutron sources prepared for use in remote afterloading cancer brachytherapy. These neutron sources are classed as special form radioactive material and as such must meet certain Regulations prescribed by the U.S. Department of Transportation. This document describes the tests that have been performed and shows that this group of medical sources does meet the applicable DOT Regulations. The doubly encapsulated neutron sources are fabricated by the Savannah River Laboratory and are loaned by the U.S. Energy Research and Development Administration under contract agreement to medical organizations for evaluation of 252Cf in the treatment of cancer

  4. Response of CR-39 plastic track detector to 239Pu and 252Cf sources

    International Nuclear Information System (INIS)

    CR-39 plastic track detectors have been irradiated with 239Pu and 252Cf sources separately at nuclear physics laboratory B.H.U., Varanasi to investigate track recording properties of detector material. All detectors etched in 6.25N NaOH solution at different temperatures for different hours. The bulk and track etch rates are calculated for both detectors (irradiated by 239Pu and 252Cf sources separately). The diameter and sensitivity along the trajectory of the track have been determined at different temperatures. (author)

  5. Water-extended polyester neutron shield for a 252Cf neutron source

    International Nuclear Information System (INIS)

    A Monte Carlo study to determine the shielding features to neutrons of water-extended polyester was carried out. During calculations, 252Cf and shielding were modelled and the neutron spectra as well as the H*(10) were calculated in four sites. The calculation was extended to include a water shielding, the source in vacuum and in air. Besides neutron shielding characteristics, the Kerma in air due to gammas emitted by 252Cf and due to capture γ rays in the shielding were included. (authors)

  6. Terrestrial Sources of Perfluorinated Gases: Excess CF4 and SF6 in Mojave Desert Groundwaters

    Science.gov (United States)

    Deeds, D. A.; Vollmer, M. K.; Kulongoski, J. T.; Miller, B. R.; Hilton, D. R.; Izbicki, J. A.; Harth, C. M.; Weiss, R. F.

    2004-12-01

    The recent discovery of perfluorinated gases in fluid inclusions of granites and fluorites suggests a geologic source for the estimated 40 parts-per-trillion (ppt) of tetrafluoromethane (CF4) and SF6) in the preindustrial atmosphere. The accumulation of these gases in groundwaters with long residence times enables the detection of even small emissions from the surrounding aquifer material. We have measured high concentrations of CF4 and SF6 in groundwaters from the Mojave Desert, California. Dissolved SF6 was extracted by a purge and trap technique and analyzed by gas chromatography with electron capture detection. Dissolved CF4 was sampled by headspace extraction, using liquid helium to cryofocus the analytes prior to injection into the Medusa gas chromatograph/quadrupole mass spectrometer analytical system. Current precisions and accuracies for these measurements are on the order of 2% for both gases. Initial measurements of dissolved CF4 concentrations range from ˜0.05 to ˜1.5 pmol kg-1, about 5 to 15 times higher than expected for water in equilibrium with the preindustrial atmosphere at the local temperature and altitude of the recharge site. SF6 concentrations range from ˜0.3 to ˜16 fmol kg-1, up to several thousand times higher than expected for air-saturated water. Taking into account the large uncertainties in the estimated preindustrial atmospheric concentration of SF6, and in the estimated atmospheric lifetimes of both SF6 and CF4, the ratio of their excess abundances in Mojave Desert groundwaters agrees within an order of magnitude with the estimated ratio of natural fluxes required to sustain their preindustrial atmospheric concentrations. Relationships among dissolved CF4 and SF6 concentrations and the other geochemical properties of the aquifer, including groundwater residence times (ages), helium abundances and isotopic ratios, and fluoride concentrations will be presented.

  7. Frequency spectrum analysis of 252Cf neutron source based on LabVIEW

    International Nuclear Information System (INIS)

    The frequency spectrum analysis of 252Cf Neutron source is an extremely important method in nuclear stochastic signal processing. Focused on the special '0' and '1' structure of neutron pulse series, this paper proposes a fast-correlation algorithm to improve the computational rate of the spectrum analysis system. And the multi-core processor technology is employed as well as multi-threaded programming techniques of LabVIEW to construct frequency spectrum analysis system of 252Cf neutron source based on LabVIEW. It not only obtains the auto-correlation and cross correlation results, but also auto-power spectrum,cross-power spectrum and ratio of spectral density. The results show that: analysis tools based on LabVIEW improve the fast auto-correlation and cross correlation code operating efficiency about by 25% to 35%, also verify the feasibility of using LabVIEW for spectrum analysis. (authors)

  8. Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement

    International Nuclear Information System (INIS)

    The purpose of this work is to evaluate the dose rate distribution and to determine the boron effect on dose rate distribution for 252Cf brachytherapy source. This study was carried out using a Monte Carlo simulation. To validate the Monte Carlo computer code, the dosimetric parameters were determined following the updated TG-43 formalism and compared with current literature data. The validated computer code was then applied to evaluate the neutron and photon dose distribution and to illustrate the boron loading effect.

  9. Experiment research on single event burnout of power MOSFET devices with 252Cf source

    International Nuclear Information System (INIS)

    The method in simulation of radiation effect test by 252Cf source was introduced, and the single event burnout experiment was carried out. The research result indicates that power MOSFET devices should be operated at the lowest voltage range un- der the radiation environment in the space, and adding a resister to confine the current in the circuit is an effective reinforce to avoid single event burnout. (authors)

  10. Calculated neutron air kerma strength conversion factors for a generically encapsulated Cf-252 brachytherapy source

    CERN Document Server

    Rivard, M J; D'Errico, F; Tsai, J S; Ulin, K; Engler, M J

    2002-01-01

    The sup 2 sup 5 sup 2 Cf neutron air kerma strength conversion factor (S sub K sub N /m sub C sub f) is a parameter needed to convert the radionuclide mass (mu g) provided by Oak Ridge National Laboratory into neutron air kerma strength required by modern clinical brachytherapy dosimetry formalisms indicated by Task Group No. 43 of the American Association of Physicists in Medicine (AAPM). The impact of currently used or proposed encapsulating materials for sup 2 sup 5 sup 2 Cf brachytherapy sources (Pt/Ir-10%, 316L stainless steel, nitinol, and Zircaloy-2) on S sub K sub N /m sub C sub f was calculated and results were fit to linear equations. Only for substantial encapsulation thicknesses, did S sub K sub N /m sub C sub f decrease, while the impact of source encapsulation composition is increasingly negligible as Z increases. These findings are explained on the basis of the non-relativistic kinematics governing the majority of sup 2 sup 5 sup 2 Cf neutron interactions. Neutron kerma and energy spectra resul...

  11. Importance of the neutrons kerma coefficient in the planning of Brachytherapy treatments with Cf-252 sources

    International Nuclear Information System (INIS)

    The Cf-252 is a fast neutrons emitting radioisotope by spontaneous fission that can be used as sealed source in medicine applications, industry and research. Commercially its offer sources of different sizes, compact and with a fast neutrons emission of the order of 106 n/s-μg and an energy spectra that presents respectively maxim and average energy in 2.1 MeV and 0.7 MeV. In medicine new applications are being developed for the treatment of patient with hypoxic and voluminous tumors, where the therapy with photons has not given positive results, as well as for the protocols of therapy treatment by boron neutron capture, where very small sources of Cf-252 will be used with the interstitial brachytherapy technique of high and low dose rate. In this work an analysis of how the small differences that exist in the elementary composition of 4 wicked tumors, 4 ICRU healthy tissues and 3 substitute materials of ICRU tissue used in dosimetry are presented, its generate changes in the neutrons kerma coefficient in function of the energy and consequently in the absorbed dose in the interval of 11 eV to 29 MeV. These differences can produce maximum variations of the neutron kerma coefficients ratio for En > 1 keV of the one: 15% tumor/ICRU guest healthy tissue, 12% ICRU tumor/muscle, 12% ICRU healthy tissues ICRU/ICRU muscle, 22% substitutes tissue/tumor and 22% ICRU substitutes tissue/muscle. Also, it was found that the average value of the neutrons kerma coefficient for the 4 wicked tumors is from 6% to 7% smaller that the average value for the soft tissue in the interval energy of interest for therapy with fast neutrons with En > 1 MeV. These results have a special importance during the planning process of brachytherapy treatments with sources of 252Cf, to optimize and to individualize the patients treatments. (Author)

  12. Measurement of the neutron spectrum and ambient neutron dose rate equivalent from the small 252Cf source at 1 meter

    International Nuclear Information System (INIS)

    NASA Langley Research Center requested a measurement of the neutron spectral distribution and fluence from the 252Cf source (model NS-120, LLNL serial # 7001677, referred as the SMALL Cf source) and determination of the ambient neutron dose rate equivalent and kerma at 100 cm for the Radiation Budget Instrument Experiment (Rad-X). The dosimetric quantities should be based on the neutron spectrum and the current neutron-to-dose conversion coefficients.

  13. Use of MCNP to compare the response of dose deposited in the TLD 100, TLD 600 and TLD 700 in radiation fields due to {sup 60}Co and {sup 241}AmBe source; Uso do MCNP para comparacao das respostas de dose depositada nos TLD 100, TLD 600 e TLD 700 em campos de irradiacao devido a fontes de {sup 60}Co e {sup 241}AmBe

    Energy Technology Data Exchange (ETDEWEB)

    Cavalieri, Tassio A.; Castro, Vinicius A.; Siqueira, Paulo T.D., E-mail: tassio.cavalieri@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-08-15

    The successes of Boron Neutron Capture Therapy (BNCT) depend on the ability to deliver an adequate irradiation field to the target cells. Neutron beams used in BNCT are mostly driven from reactors and therefore, not only have a neutron energy range which far exceeds the thermal region but also do have a great gamma component. Beam characterization and dosimetry are consequently one of the essential procedures to be overcome to properly apply this technique. One of the methods currently used in mixed field (field containing both neutron and gamma) characterization, lies on the use of a pair of detectors with distinct responses to each beam component. But this technique needs to be better understood of how each thermoluminescent dosimeter (TLD) behaves in a mixed field or in a pure field. This work presents the results of a set of simulations performed in order to analyze the response of three ordinary types of TLDs - TLD 100, TLD 600 and TLD 700 - submitted to different irradiation fields from a Cobalt source and an Americium-Beryllium source inside a paraffin disk. And is also a possible method for performing the selection and calibration of theses TLDs. (author)

  14. Possibilities of detection of valuable metals in manganese nodules utilizing of Cf 252 neutron source

    International Nuclear Information System (INIS)

    For a long-term maintainance of the supply of non-iron metals the exploration of marine ore deposits becomes more and more important. In the special case of the so-called manganese nodules deposited on the deep ocean floor, a rather continuous method is required, by which the metals manganese, copper, nickel, cobalt and iron, or some of them, could be determined in situ, for short with an analytical error of about 20 to 50% analysis times. The possibility of performing such analyses by aid of the capture gamma radiation induced by a Cf 252 neutron source - which appeared to be promising - has been tested experimentally, simultaneous of referring to the maximum analizing time of 10 min demanded by application. For this purpose genuine manganese nodules have been irradiated at a 1 mg Cf 252 source. Decay gamma radiation as well as capture gamma radiation have been measured individually. The spectra from these measurements allowed to determine the statistical error of characteristic lines of the individual metal and thus their detectability. The measurement of decay gamma radiation (up to 2 MeV) showed that, within the short analyzing time, only manganese is detectable with a relative error of 1% referring to 10 g sample material. The measurement of capture gamma radiation (up to 10 MeV) verified the detection of the five metals of interest (Mn, Fe, Cu, Ni). An increase of the sample quantity up to 10 kg, corresponding to realistic prospection conditions, yielded within 10 min following relative errors: Mn 3 to 4%, Fe 7 to 8%, Cu 20 to 25%, Co 50% and Ni 12 to 20%. An experimental arrangement with the Cf 252 source and the sample situated in a water tank proved the practicability of such measurements even in presence of large quantities of water. (orig.)

  15. Analysis of molasses samples from various sugar industries in Maharashtra using 252Cf neutron source

    International Nuclear Information System (INIS)

    The molasses samples from various sugar industries in Maharashtra State have been analysed for their physico-chemical characteristics as well as elemental contents. The elements sodium, potassium, chlorine and manganese were determined using 252Cf neutron source by instrumental neutron activation analysis (INAA). Other parameters such as ash, moisture, total dissolved solids, pH as well as element Ca were estimated by usual conventional chemical methods. The percentage of various parameters varies from industry to industry and the concentration of elements is found in the order K > Ca > Cl > Na> Mn. (author). 3 refs., 2 tabs

  16. Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Ghassoun, J. [EPRA, Department of Physics, Faculty of Sciences Semlalia, PO Box: 2390, 40000 Marrakech (Morocco)], E-mail: ghassoun@ucam.ac.ma; Mostacci, D.; Molinari, V. [Laboratorio di Ingegneria Nucleare di Montecuccolino, via dei Colli 16, 40136 Bologna (Italy); Jehouani, A. [EPRA, Department of Physics, Faculty of Sciences Semlalia, PO Box: 2390, 40000 Marrakech (Morocco)

    2010-02-15

    The purpose of this work is to evaluate the dose rate distribution and to determine the boron effect on dose rate distribution for {sup 252}Cf brachytherapy source. This study was carried out using a Monte Carlo simulation. To validate the Monte Carlo computer code, the dosimetric parameters were determined following the updated TG-43 formalism and compared with current literature data. The validated computer code was then applied to evaluate the neutron and photon dose distribution and to illustrate the boron loading effect.

  17. Effect of tissue inhomogeneities on dose distributions from Cf-252 brachytherapy source.

    Science.gov (United States)

    Ghassoun, J

    2013-01-01

    The Monte Carlo method was used to determine the effect of tissue inhomogeneities on dose distribution from a Cf-252 brachytherapy source. Neutron and gamma-ray fluences, energy spectra and dose rate distributions were determined in both homogenous and inhomogeneous phantoms. Simulations were performed using the MCNP5 code. Obtained results were compared with experimentally measured values published in literature. Results showed a significant change in neutron dose rate distributions in presence of heterogeneities. However, their effect on gamma rays dose distribution is minimal. PMID:23069196

  18. Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement.

    Science.gov (United States)

    Ghassoun, J; Mostacci, D; Molinari, V; Jehouani, A

    2010-02-01

    The purpose of this work is to evaluate the dose rate distribution and to determine the boron effect on dose rate distribution for (252)Cf brachytherapy source. This study was carried out using a Monte Carlo simulation. To validate the Monte Carlo computer code, the dosimetric parameters were determined following the updated TG-43 formalism and compared with current literature data. The validated computer code was then applied to evaluate the neutron and photon dose distribution and to illustrate the boron loading effect. PMID:19889549

  19. Neutron dose rate for {sup 252} Cf AT source in medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, L.; Balcazar, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Azorin, J. [UAM-I, 09340 Mexico D.F. (Mexico); Francois, J.L. [FI-UNAM, 04510 Mexico D.F. (Mexico)

    2006-07-01

    The AAPM TG-43 modified protocol was used for the calculation of the neutron dose rate of {sup 252}Cf sources for two tissue substitute materials, five normal tissues and six tumours. The {sup 252}Cf AT source model was simulated using the Monte Carlo MCNPX code in spherical geometry for the following factors: a) neutron air kerma strength conversion factor, b) dose rate constant, c) radial dose function, d) geometry factor, e) anisotropy function and f) neutron dose rate. The calculated dose rate in water at 1 cm and 90 degrees from the source long axis, using the Watt fission spectrum, was D{sub n}(r{sub 0}, {theta}{sub 0})= 1.9160 cGy/h-{mu}g. When this value is compared with Rivard et al. calculation using MCNP4B code, 1.8730 cGy/h-{mu}g, a difference of 2.30% is obtained. The results for the reference neutron dose rate in other media show how small variations in the elemental composition between the tissues and malignant tumours, produce variations in the neutron dose rate up to 12.25%. (Author)

  20. [Radiation safety during work on the ANET-V therapeutic apparatus with 252Cf sources].

    Science.gov (United States)

    Chekhonadskiĭ, V N; Drygin, V N; Vaĭnberg, M Sh; Komar, V Ia; Elisiutin, G P

    1985-03-01

    The Soviet ANET-W intracavitary neutron therapy apparatus is charged with 252Cf sources, the total mass of the radionuclide being 2100 micrograms. The radiation exposure of the staff has been studied and the results presented. Possible emergency situations have been analysed, methods of their prevention and liquidation worked out. Induced radioactivity in the patient's body has been estimated. Radiation dose levels for the medical staff are 10-15 times lower for the ANET-W apparatus than those for 252Cf sources administered by the manual series system but 10 times higher than those for the AGAT-W gamma-apparatus. The design, blocking system and emergency reset of the sources provide for safe work on the ANET-W apparatus. During liquidation of an emergency situation irradiation of the staff does not exceed 0.3 of the annual maximum tolerance dose. The level of induced activity in the patient's body is insignificant as in 10.5 min it does not exceed background values. PMID:3982256

  1. Cf-252 source-detector method for ADS and core reload in NPP's

    International Nuclear Information System (INIS)

    Accurate measurements of the subcritical level is an important research topic in the development of Accelerator Driven Systems (ADS) as well as for the determination of the subcriticality level in storage pools or during loading operations in LWR's. For ADS, it is clear that an accurate absolute determination of the subcriticality level is of paramount importance, since these systems are supposed to remain subcritical at all times. The core reload of NPP's is commonly executed by adopting the subcritical approach. This procedure allows to safely predicting the critical mass based on different subcritical states of the reactor, but it doesn't allow to obtain the subcriticality value of the different subcritical states during reload. Since practice in NPP's has shown that it would be very valuable to have access to the absolute value of the subcriticality, it is desirable to obtain a measurement technique that can be used for this purpose. In this project, we investigated the measurement of the multiplication factor keff in subcritical conditions in the VENUS reactor using the so-called 252Cf source-detector method. These measurements are the first step in the validation process of the 252Cf source-detector method to be used for subcriticality determination in ADS and during core reload in NPP's

  2. Accurate plutonium waste measurements using the 252Cf add-a- source technique for matrix corrections

    International Nuclear Information System (INIS)

    We have developed a new measurement technique to improve the accuracy and sensitivity of the nondestructive assay (NDA) of plutonium scrap and waste. The 200-ell drum assay system uses the classical NDA method of counting passive-neutron coincidences from plutonium but has added the new features of ''add-a-source'' to improve the accuracy for matrix corrections and statistical techniques to improve the low-level detectability limits. The add-a-source technique introduces a small source of 252Cf (10-8 g) near the external surface of the sample drum. The drum perturbs the rate at which coincident neutrons from the 252Cf are counted. The perturbation provides the data to correct for the matrix and plutonium inside the drum. The errors introduced from matrix materials in 200-ell drums have been reduced by an order of magnitude using the add-a-source technique. In addition, the add-a-source method can detect unexpected neutron-shielding material inside the drum that might hide the presence of special nuclear materials. The detectability limit of the new waste-drum assay system for plutonium is better than prior systems for actual waste materials. For the in-plant installation at a mixed-oxide fabrication facility, the detectability limit is 0.73 mg of 24OPu (or 2.3 mg of high-burnup plutonium) for a 15-min. measurement. For a drum containing 100 kg of waste, this translates to about 7 nCi/g. This excellent sensitivity was achieved using a special low-background detector design, good overhead shielding, and statistical techniques in the software to selectively reduce the cosmic-ray neutron background

  3. Depth dose distribution for sup 252 Cf source using solid state detectors

    Energy Technology Data Exchange (ETDEWEB)

    Moustafa, H.R.; Mohamed, R.L. (Al Azhar Univ. of Girls, Cairo (Egypt). Physics Dept.); Abdel-Wahab, M.S.; El Fiki, S.; El Enany, N. (Ain Shams Univ., Cairo (Egypt). Dept. of Physics); Eissa, H.M.; El Feky, M.A. (National Inst. for Standards, Cairo (Egypt). Academy of Scientific Research and Technology)

    1991-01-01

    LiF (600 and 700) and solid state nuclear track detectors were used for measuring fast and thermal neutrons and {gamma}-ray doses from {sup 252}Cf source in tissue equivalent phantom. Conversion factors as well as related quality factors were used for absorbed and equivalent dose calculations. Two exposure positions were used: Source at 30 cm and in contact with phantom surface. The contribution of thermal and fast neutrons in both absorbed dose and equivalent dose reaches a maximum value at 3.5 cm while the maximum for {gamma}-ray is at 8.5 cm. The build up and attenuation in tissue and the corresponding relaxation length were evaluated. (orig.).

  4. GEANT4 and PHITS simulations of the shielding of neutrons from $^{252}$Cf source

    CERN Document Server

    Shin, Jae Won

    2014-01-01

    Neutron shielding simulations by using GEANT4 and PHITS code are performed. As a neutron source, $^{252}$Cf is considered and the energy distribution of the neutrons emitted from $^{252}$Cf is assumed the Watt fission spectrum. The neutron dose equivalent rates with and without the shield are estimated for shielding materials such as graphite, iron, polyethylene, NS-4-FR and KRAFTON-HB. For the neutron shielding simulations by using GEANT4, high precision (G4HP) model with G4NDL 4.2 based on ENDF-VII data are used. And for PHITS simulations, JENDL-4.0 library are used for the same purpose. It is found that differences between the shielding calculations by using GEANT4 with G4NDL 4.2 and PHITS with JENDL-4.0 library are not significant for all cases considered in this work. We investigate the accuracy of the neutron dose equivalent rates obtained from GEANT4 and PHITS by comparing our simulation results with experimental data and other values calculated earlier. Calculated neutron dose equivalent rates agree w...

  5. Characteristics of the simulated workplace neutron fields using a 252Cf source surrounded with cylindrical moderators

    International Nuclear Information System (INIS)

    The authors established the simulated workplace neutron fields using a 252Cf source surrounded with cylindrical moderators at the Japan Nuclear Cycle Development Inst. (JNC), Tokai Works. The moderators are annular cylinders made of polymethyl methacrylate and steel. The neutron energy spectrum at the reference calibration point was evaluated from the calculations by MCNP-4B and the measurements by the Bonner multisphere spectrometer and the hydrogen-filled proportional counters. The calculated neutron spectra were in good agreements with the measured ones. These fields can provide the realistic neutron spectra similar to those encountered around the glove-boxes of the fabrication process of MOX (PuO2-UO2 mixed oxide) fuel. (authors)

  6. Effect of tissue Inhomogeneities on dose distributions from Cf-252 brachytherapy source

    International Nuclear Information System (INIS)

    The Monte Carlo method was used to determine the effect of tissue inhomogeneities on dose distribution from a Cf-252 brachytherapy source. Neutron and gamma-ray fluences, energy spectra and dose rate distributions were determined in both homogenous and inhomogeneous phantoms. Simulations were performed using the MCNP5 code. Obtained results were compared with experimentally measured values published in literature. Results showed a significant change in neutron dose rate distributions in presence of heterogeneities. However, their effect on gamma rays dose distribution is minimal. - Highlights: ► The effect of tissue inhomogeneities on dose distribution has been investigated. ► A comparison of our results with experimental data available in the literature is presented. ► Obtained results showed a significant change in neutron dose rate distributions.

  7. Computer analysis of nuclear track emulsion exposed to thermal neutrons and Cf source

    Science.gov (United States)

    Mamatkulov, K. Z.; Ambřozová, I.; Artemenkov, D. A.; Bradnova, V.; Kamanin, D. V.; Kattabekov, R. R.; Majling, L.; Marey, A.; Ploc, O.; Rusakova, V. V.; Stanoeva, R.; Turek, K.; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.

    2016-02-01

    Application of the nuclear track emulsion technique (NTE) in radioactivity and nuclear fission studies is discussed. It is suggested to use a HSP-1000 automated microscope for searching for a collinear cluster tri-partition of heavy nuclei implanted in NTE. Calibrations of α-particles and ion ranges in a novel NTE are carried out. Surface exposures of NTE samples to a Cf-252 source started. Planar events containing fragments and long-range α-particles as well as fragment triples only are studied. Splittings induced by thermal neutrons are studied in boron-enriched emulsion. Use of the image recognition program ”ImageJ” for obtaining characteristics of individual events and for events from the large scan area is presented.

  8. Measurement of thermal neutron cross-sections and resonance integrals for sup 7 sup 1 Ga(n,gamma) sup 7 sup 2 Ga and sup 7 sup 5 As(n,gamma) sup 7 sup 6 As by using sup 2 sup 4 sup 1 Am-Be isotopic neutron source

    CERN Document Server

    Karadag, M; Tan, M; Oezmen, A

    2003-01-01

    Thermal neutron cross-sections and resonance integrals for the sup 7 sup 1 Ga(n,gamma) sup 7 sup 2 Ga and sup 7 sup 5 As(n,gamma) sup 7 sup 6 As reactions were measured by the activation method. The experimental samples with and without a cylindrical Cd shield case in 1 mm wall thickness were irradiated in an isotropic neutron field of the sup 2 sup 4 sup 1 Am-Be neutron source. The induced activities in the samples were measured by high-resolution gamma-ray spectrometry with a calibrated reverse-electrode germanium detector. Thermal neutron cross-sections for 2200 m/s neutrons and resonance integrals for the sup 7 sup 1 Ga(n,gamma) sup 7 sup 2 Ga and sup 7 sup 5 As(n,gamma) sup 7 sup 6 As reactions have been obtained relative to the reference values, sigma sub 0 =13.3+-0.1 b and I sub 0 =14.0+-0.3 b for the sup 5 sup 5 Mn(n,gamma) sup 5 sup 6 Mn reaction as a single comparator. The necessary correction factors for gamma attenuation, thermal neutron and resonance neutron self-shielding effects were taken into...

  9. Measurements of gamma-ray dose from a moderated 252Cf source

    International Nuclear Information System (INIS)

    The gamma-ray dose fraction from a moderated 252Cf source was determined by using three types of dosimetry systems. Measurements were carried out in air at a distance of 35 cm from the surface of the moderating sphere (50 cm from the source which is at the center of the sphere) to the geometrical center of each detector. The moderating sphere is 0.8-mm-thick stainless steel shell filled with D2O and covered with 0.5 mm of cadmium. Measurements were also carried out with instruments and dosimeters positioned at the surface of a 40 cm x 40 cm x 15 cm plexiglass irradiation phantom whose front surface was also 35 cm from the surface of the moderating sphere. A-150 tissue-equivalent (TE) plastic ionization chambers and a TE proportional counter (TEPC) were used to measure tissue dose, from which the neutron dose equivalent was computed. The ratio of gamma-ray dose to the neutron dose equivalent was determined by using a relatively neutron-insensitive Geiger-Mueller (GM) counter and thermoluminescent dosimeters (TLD). In addition, the event-size spectrum measured by the TEPC was also used to compute the gamma-ray dose fraction. The average value for the ratio of gamma-ray dose to neutron dose equivalent was found to be 0.18 with an uncertainty of about +-18%

  10. A comparison of dosimetric parameters and dose distribution around CF -252 and IR-192 LDR Brachytherapy Sources

    International Nuclear Information System (INIS)

    Full text: The purpose of this work is the evaluation and comparison of the dose rate distributions around a 252Cf Applicator Tube (AT) and 192Ir LDR sources. The dosimetric parameters were determined for both sources according to the updated AAPM TG-43U1 protocol. The calculations were performed using the Monte Carlo N-particle MCNP code, version 5C. To validate the results of this study, they were compared to experimental and analytical dosimetric data available in the literature for similar source configurations. After validation, the Monte Carlo computer code was applied to investigate the difference between dose rate distributions around the two brachytherapy sources, with the purpose of comparing their efficiency in treatment. The data so obtained also provide further information about spatial dose distributions and are important for detailed treatment planning with 252 Cf or 192Ir LDR sources for interstitial and intracavitary therapy

  11. Design and construction of an explosive detection system by Tna methods, using 252Cf radioisotope source

    International Nuclear Information System (INIS)

    Bombs concealed in luggage have threatened human life and property throughout the world's traffic. The plastic explosives could not checked by the X-ray detecting device. Thermal Neutron Activation method has been tested in the present work for non-destructive detection of explosives. A radioisotope neutron source 252Cf and two gamma spectroscopy systems have been used as a tool to find explosives, regardless of the bomb's shape and the packing materials. The MCNP code has been used to design the neutronic section of the system. The measured thermal neutron fluxes by the gold foils in some location of the system were in good agreement with those data obtained by the MCNP code. Also, detection limits for nitrogen in various counting times were measured. The measurements show that the system is capable to detect 417 gr of HMX explosive material (158 gr nitrogen) by 10 minutes of counting time. To modify the system and to decrease the detection limits some opinions are given

  12. Neutron and photon dosimetry at an installed high emission 252Cf source

    International Nuclear Information System (INIS)

    The irradiation hazard was studied in work with the 252Cf fission spectrum neutron source (with a total amount of 1 mg) with a total neutron emission of 2.3x109 s-1. Gamma radiation and neutrons were measured using film dosemeters and track detectors in association with fissionable material (U enriched to 6.5% of 235U and an alloy of Th + 0.5% of natural U). Radiation doses and dose equivalents were assessed by methods developed at the UVVVR Personnel Dosimetry Laboratory. Relations were determined of fast and slow neutrons, this with shielding the staircase with moulded NEUTROSTOP 3B bricks and with the staircase unshielded. It was found that in the control room the dose equivalent did not exceed 1.5x105 Sv.h-1, i.e., 1.5 mrem/h. With the staircase shielded the dose equivalent decreased by about 1/3. Delayed neutron fluence only increased near the shielding; their low biological efficiency, however, does not affect the total dose and dose equivalent values. Also studied were changes in spectra and the respective spectral part proportions. It was found that the slow neutron contribution increased with distance and the presence of a moderating medium up to the equilibrium state when only an even decrease started of the dosimetric values of all spectral components. (B.S.)

  13. Effects of scattered neutrons on the neutron radiation field generated by Cf-252 neutron source with a shield

    International Nuclear Information System (INIS)

    Background: Shields are commonly constructed for a radionuclide neutron source m an actual calibration room in practice. Purpose: Monte Carlo (MC) calculation and experiments were applied to evaluate the effects of scattered neutrons on the neutron radiation field generated by Cf-252 neutron source with a shield. Methods: The effects of scattered neutrons caused by the shield of Cf-252 neutron source were evaluated by calculating the neutron spectra, neutron flux rate and neutron ambient dose equivalent with MC simulation. Similarly, the effects of scattered neutrons caused by the walls, ground and roof of source room were analyzed. Results: The calculation results show that the neutron flux-ambient dose equivalent conversion factor changes from 385 pSv·cm2 of a bare Cf-252 radionuclide from an idealized situation to 280 pSv·cm2 with the shield. The contribution of scattered neutrons from the walls, ground and roof is proportional to the square of distance between wall and source. The experimental data on dose rate are consistent with the calculated results and indicate the reliability of this method. Conclusion: This study provides a practical and feasible way to calibrate the radiation protection instruments using a non-standard radionuclide neutron radiation field. (authors)

  14. Calculation of Ambient (H*(10)) and Personal (Hp(10)) Dose Equivalent from a 252Cf Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Traub, Richard J.

    2010-03-26

    The purpose of this calculation is to calculate the neutron dose factors for the Sr-Cf-3000 neutron source that is located in the 318 low scatter room (LSR). The dose factors were based on the dose conversion factors published in ICRP-21 Appendix 6, and the Ambient dose equivalent (H*(10)) and Personal dose equivalent (Hp(10)) dose factors published in ICRP Publication 74.

  15. Installation and measurement capacity of 3 x 592 GBq 241Am-Be neutron irradiation cell

    International Nuclear Information System (INIS)

    In this study, the installation and measurement capacity of the neutron irradiation system are investigated. First of all an irradiation geometry enabling optimum irradiation was designed for three 241Am-Be sources each of it having 592 GBq activity. Neutron irradiation system was installed after design and optimization of the system including the design of appropriate moderator and shielding were completed. Radiation safety standards of the Neutron Research Laboratory fulfilling the requirements of national regulation were achieved with unique configuration of the shielding materials. In this study the results of qualitative and quantitative detection limits obtained for Na, Al, Cl, K, Ti, V, Mn, Fe, Co, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Mo, Ru, Ag, Cd, In, Sb, I, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Yb, Lu, Hf, W, Pt, Au, Th and U elements by using the neutron irradiation cell comprising 3 x 592 GBq 241Am-Be isotopic neutron source are presented and discussed. (orig.)

  16. Atmospheric observations for quantifying emissions of point-source synthetic greenhouse gases (CF4, NF3 and HFC-23)

    Science.gov (United States)

    Arnold, Tim; Manning, Alistair J.; Li, Shanlan; Kim, Jooil; Park, Sunyoung; Fraser, Paul J.; Mitrevski, Blagoj; Steele, L. Paul; Krummel, Paul B.; Mühle, Jens; Weiss, Ray F.

    2016-04-01

    The fluorinated species carbon tetrafluoride (CF4; PFC-14), nitrogen trifluoride (NF3) and trifluoromethane (CHF3; HFC-23) are potent greenhouse gases with 100-year global warming potentials of 6,630, 16,100 and 12,400, respectively. Unlike the majority of CFC-replacement compounds that are emitted from fugitive and mobile emission sources, these gases are largely emitted from large single point sources - semiconductor manufacturing facilities (all three), aluminium smelting plants (CF4) and chlorodifluoromethane factories (HFC-23). In this work we show the potential for atmospheric measurements to understand regional sources of these gases and to highlight emission 'hotspots'. We target our analysis on measurements from two Advanced Global Atmospheric Gases Experiment (AGAGE) long term monitoring sites that are particularly sensitive to regional emissions of these gases: Gosan on Jeju Island in the Republic of Korea and Cape Grim on Tasmania in Australia. These sites measure CF4, NF3 and HFC-23 alongside a suite of greenhouse and stratospheric ozone depleting gases every two hours using automated in situ gas-chromatography mass-spectrometry instrumentation. We couple each measurement to an analysis of air history using the regional atmospheric transport model NAME (Numerical Atmospheric dispersion Modelling Environment) driven by 3D meteorology from the Met Office's Unified Model, and use a Bayesian inverse method (InTEM - Inversion Technique for Emission Modelling) to calculate yearly emission changes over a decade (2005-2015) at high spatial resolution. At present these gases make a small contribution to global radiative forcing, however, given that their impact could rise significantly and that point sources of such gases can be mitigated, atmospheric monitoring could be an important tool for aiding emissions reduction policy.

  17. 252Cf-source-correlated transmission measurements for uranyl fluoride deposit in a 24-in.-OD process pipe

    International Nuclear Information System (INIS)

    Characterization of a hydrated uranyl fluoride (UO2F2·nH2O) deposit in a 17-ft-long, 24-in.-OD process pipe at the former Oak Ridge Gaseous Diffusion Plant was successfully performed by using 252Cf-source-correlated time-of-flight (TOF) transmission measurements. These measurements of neutrons and gamma rays through the pipe from an external 2521Cf fission source were used to measure the deposit profile and its distribution along the pipe, the hydration (or H/U), and the total uranium mass. The measurements were performed with a source in an ionization chamber on one side of the pipe and detectors on the other. Scanning the pipe vertically and horizontally produced a spatial and time-dependent radiograph of the deposit in which transmitted gamma rays and neutrons were separated in time. The cross-correlation function between the source and the detector was measured with the Nuclear Weapons Identification System. After correcting for pipe effects, the deposit thickness was determined from the transmitted neutrons and H/U from the gamma rays. Results were consistent with a later intrusive observation of the shape and the color of the deposit; i.e., the deposit was annular and was on the top of the pipe at some locations, demonstrating the usefulness of this method for deposit characterization

  18. 252Cf-source-correlated transmission measurements for uranyl fluoride deposit in a 24-in-OD process pipe

    International Nuclear Information System (INIS)

    Characterization of a hydrated uranyl fluoride (UO2F2·nH2O) deposit in a 17 ft long, 24 in OD process pipe at the former Oak Ridge Gaseous Diffusion Plant was successfully performed using 252Cf-source-correlated time-of-flight (TOF) transmission measurements. These measurements of neutrons and gamma rays through the pipe from an external 252Cf fission source were used to measure the deposit profile and its distribution along the pipe, the hydration (or H/U), and the total uranium mass. The measurements were performed with a source in an ionization chamber on one side of the pipe and detectors on the other. Scanning the pipe vertically and horizontally produced a spatial and time-dependent radiograph of the deposit in which transmitted gamma rays and neutrons were separated in time. The cross-correlation function between the source and the detector was measured with the Nuclear Weapons Identification System. After correcting for pipe effects, the deposit thickness was determined from the transmitted neutrons and H/U from the gamma rays. Results were consistent with a later intrusive observation of the shape and the color of the deposit; i.e., the deposit was annular and was on the top of the pipe at some locations, demonstrating the usefulness of this method for deposit characterization

  19. 252Cf-source-correlated transmission measurements for uranyl fluoride deposit in a 24-in-OD process pipe

    Science.gov (United States)

    Uckan, T.; Wyatt, M. S.; Mihalczo, J. T.; Valentine, T. E.; Mullens, J. A.; Hannon, T. F.

    1999-02-01

    Characterization of a hydrated uranyl fluoride (UO 2F 2· nH 2O) deposit in a 17 ft long, 24 in OD process pipe at the former Oak Ridge Gaseous Diffusion Plant was successfully performed using 252Cf-source-correlated time-of-flight (TOF) transmission measurements. These measurements of neutrons and gamma rays through the pipe from an external 252Cf fission source were used to measure the deposit profile and its distribution along the pipe, the hydration (or H/U), and the total uranium mass. The measurements were performed with a source in an ionization chamber on one side of the pipe and detectors on the other. Scanning the pipe vertically and horizontally produced a spatial and time-dependent radiograph of the deposit in which transmitted gamma rays and neutrons were separated in time. The cross-correlation function between the source and the detector was measured with the Nuclear Weapons Identification System. After correcting for pipe effects, the deposit thickness was determined from the transmitted neutrons and H/U from the gamma rays. Results were consistent with a later intrusive observation of the shape and the color of the deposit; i.e., the deposit was annular and was on the top of the pipe at some locations, demonstrating the usefulness of this method for deposit characterization.

  20. Measurement of the neutron spectrum and ambient neutron dose rate equivalent from the small 252Cf source at 1 meter

    Energy Technology Data Exchange (ETDEWEB)

    Radev, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-07

    NASA Langley Research Center requested a measurement of the neutron spectral distribution and fluence from the 252Cf source (model NS-120, LLNL serial # 7001677, referred as the SMALL Cf source) and determination of the ambient neutron dose rate equivalent and kerma at 100 cm for the Radiation Budget Instrument Experiment (Rad-X). The dosimetric quantities should be based on the neutron spectrum and the current neutron-to-dose conversion coefficients.

  1. Characterization of the neutron field of the 241AmBe in a calibration room

    International Nuclear Information System (INIS)

    The field of neutrons produced by an isotopic source of neutrons of 241 Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

  2. Replacing a 252Cf source with a neutron generator in a shuffler - a conceptual design performed with MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Schear, Melissa A [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory

    2009-01-01

    The {sup 252}Cf shuffler has been widely used in nuclear safeguards and radioactive waste management to assay fissile isotopes, such as {sup 235}U or {sup 239}Pu, present in a variety of samples, ranging from small cans of uranium waste to metal samples weighing several kilograms. Like other non-destructive assay instruments, the shuffler uses an interrogating neutron source to induce fissions in the sample. Although shufflers with {sup 252}Cf sources have been reliably used for several decades, replacing this isotopic source with a neutron generator presents some distinct advantages. Neutron generators can be run in a continuous or pulsed mode, and may be turned off, eliminating the need for shielding and a shuffling mechanism in the shuffler. There is also essentially no dose to personnel during installation, and no reliance on the availability of {sup 252}Cf. Despite these advantages, the more energetic neutrons emitted from the neutron generator (141 MeV for D-T generators) present some challenges for certain material types. For example when the enrichment of a uranium sample is unknown, the fission of {sup 238}U is generally undesirable. Since measuring uranium is one of the main uses of a shuffler, reducing the delayed neutron contribution from {sup 238}U is desirable. Hence, the shuffler hardware must be modified to accommodate a moderator configuration near the source to tailor the interrogating spectrum in a manner which promotes sub-threshold fissions (below 1 MeV) but avoids the over-moderation of the interrogating neutrons so as to avoid self-shielding. In this study, where there are many material and geometry combinations, the Monte Carlo N-Particle eXtended (MCNPX) transport code was used to model, design, and optimize the moderator configuration within the shuffler geometry. The code is then used to evaluate and compare the assay performances of both the modified shuffler and the current {sup 252}Cf shuffler designs for different test samples. The

  3. Monte Carlo simulation optimisation of zinc sulphide based fast-neutron detector for radiography using a 252Cf source

    Science.gov (United States)

    Meshkian, Mohsen

    2016-02-01

    Neutron radiography is rapidly extending as one of the methods for non-destructive screening of materials. There are various parameters to be studied for optimising imaging screens and image quality for different fast-neutron radiography systems. Herein, a Geant4 Monte Carlo simulation is employed to evaluate the response of a fast-neutron radiography system using a 252Cf neutron source. The neutron radiography system is comprised of a moderator as the neutron-to-proton converter with suspended silver-activated zinc sulphide (ZnS(Ag)) as the phosphor material. The neutron-induced protons deposit energy in the phosphor which consequently emits scintillation light. Further, radiographs are obtained by simulating the overall radiography system including source and sample. Two different standard samples are used to evaluate the quality of the radiographs.

  4. Experimental research on specific activity of 24Na using Chinese reference man phantom irradiated by 252Cf neutrons source

    International Nuclear Information System (INIS)

    Objective: To investigate the specific activity of '24Na per unit neutron fluence, AB/Φ,in blood produced for Chinese reference man irradiated by 252Cf neutron source,and to analyze the effects of scattering neutrons from ground,wall,and ceiling in irradiation site on it.Methods: A 252Cf neutron source of 3×108 n/s and the anthropomorphic phantom were used for experiments. The phantom was made from 4 mm thick of outer covering by perspex and the liquid tissue-equivalent substitute in it. The data of phantom dimensions fit into Chinese reference man.The weight ratios of H, N, O and C in substitute equal from source to long axis of phantom were 1.1, 2.1, 3.1 and 4.1 m, respectively. Both the neutron source and the position of xiphisternum of the phantom were 1.6 m above the floor. Results: The average specific activity of 24Na per unit neutron fluence was related to the irradiation-distances, d, and its maximum value, AB/ΦM, deduced by experimental data was about 1.85×10-7 Bq·cm2·g-1. Conclusions: The AB/ΦM corresponds to that of phantom irradiated by plane-parallel beams, and the value is about more 3% than that by BOMAB phantom reported in literature. It has shown that floor-(wall-)scattered neutrons in irradiation site have significant contribution to the specific activity of 24Na, but they contributed relatively little to the induced neutron doses. Consequently,using the specific activity of 24Na for assessing accidental neutron doses received by an individual, the contribution of scattered neutrons in accident site will lead dose to be overestimated, and need to be correct. (authors)

  5. Feasibility of fissile mass assay of spent nuclear fuel using 252Cf-source-driven frequency-analysis

    International Nuclear Information System (INIS)

    The feasibility was evaluated using MCNP-DSP, an analog Monte Carlo transport cod to simulate source-driven measurements. Models of an isolated Westinghouse 17x17 PWR fuel assembly in a 1500-ppM borated water storage pool were used. In the models, the fuel burnup profile was represented using seven axial burnup zones, each with isotopics estimated by the PDQ code. Four different fuel assemblies with average burnups from fresh to 32 GWd/MTU were modeled and analyzed. Analysis of the fuel assemblies was simulated by inducing fission in the fuel using a 252Cf source adjacent to the assembly and correlating source fissions with the response of a bank of 3He detectors adjacent to the assembly opposite the source. This analysis was performed at 7 different axial positions on each of the 4 assemblies, and the source-detector cross-spectrum signature was calculated for each of these 28 simulated measurements. The magnitude of the cross-spectrum signature follows a smooth upward trend with increasing fissile material (235U and 239Pu) content, and the signature is independent of the concentration of spontaneously fissioning isotopes (e.g., 244Cm) and (α,n) sources. Furthermore, the cross-spectrum signature is highly sensitive to changes in fissile material content. This feasibility study indicated that the signature would increase ∼100% in response to an increase of only 0.1 g/cm3 of fissile material

  6. Study the Possibility of measuring Heavy Metals Arising from Gold Mining Sample using 252Cf Neutron Source

    International Nuclear Information System (INIS)

    Mining activities contribute immensely to trace element pollution .The present work studied the possibility of measuring heavy metals arising from gold mining areas Eastern Desert in Egypt using the isotopic 252Cf neutron source. 38.5 g of the sample is irradiated in a neutron field of 252Cf for 36.75 days and 0.3 mg of the sample is irradiated at the Pneumatic Irradiation Rabbit System (PIRS) built in the vertical thermal column of the ET-RR-2 reactor . The induced activities in the samples are measured using two high resolution fray spectrometry systems (including two calibrated HPGe detectors). The kο standardization neutron activation analysis (kο-NAA) method was used to analyze the sample under investigation. Thermal to epithermal flux ratio fat the two irradiation positions are measured. The obtained results indicated that the values of the suspected heavy metals such as sodium, magnesium, potassium, manganese, arsenic, ruthenium and tantalum were higher than the background values, signifying accumulation of these heavy metals due to gold mining activities .The accuracy and precision of the method has been evaluated

  7. A new Am-Be PGNAA setup for element determination in aqueous solution.

    Science.gov (United States)

    Yongsheng, Ling; Wenbao, Jia; Daqian, Hei; Qing, Shan; Can, Cheng; Haojia, Zhang; Wenyu, Hou; Yanquan, He; Da, Chen

    2014-11-12

    A new prompt-gamma neutron activation analysis (PGNAA) setup has been designed for element determination in aqueous solution with a 300 mCi (241)Am-Be neutron source and a 4in.×3in. (diameter×height) BGO detector, uncooled. A polyethylene cylindrical sample container approximately 40cm in outer radius and 80cm in height was used. To reduce the neutron dose in the detector, a block of 5cm thickness Li2CO3 was placed between the source and the detector for separation, but no gamma-blocker was used. By adjusting the position of the detector and optimizing the geometrical conditions of the setup, the element detection limit with a low activity neutron source was further improved. This methodology was checked by simulations with chlorine, mercury and cadmium determination and by experiments with chlorine determination in aqueous samples. The results show a good linear relationship between chlorine concentration and the count of its characteristic peak, and the detection limit of chlorine can reach 41.7mg/L with a collection time of 3600s for each spectrum. Additionally, a linear relationship was identified between mercury concentration and the count of its characteristic peak, but for cadmium, a non-linear relationship was observed in the simulations. PMID:25464204

  8. Experimental optimisation of a moderated sup 2 sup 5 sup 2 Cf source for land mine detection

    CERN Document Server

    Zuin, L; Fabris, D; Lunardon, M; Nebbia, G; Viesti, G; Cinausero, M; Fioretto, E; Prete, G; Palomba, M; Pantaleo, A

    2000-01-01

    A moderated sup 2 sup 5 sup 2 Cf source to be used for the detection of buried land mines has been experimentally characterised. The moderating structure was obtained by using an inner sphere of Pb embedded in a high-density polyethylene (HDPe) brick assembly. The number of capture events in a Cd sample placed outside the structure was used, by varying the dimensions of the brick assembly, to determine the best moderator geometry. Furthermore, the detection of land mines by neutron capture reaction on nitrogen nuclei contained in the explosive was simulated by in field measurements placing the Cd sample at different depths in the soil. The obtained results are compared with predictions from Monte Carlo calculations.

  9. Preliminary study on biological effects of pea seeds (Pisum sativum L.) induced by 252Cf neutron source

    International Nuclear Information System (INIS)

    Background: The doses and biological effects of irradiated plants have been studied and reported widely. In the research, Co-60 gamma-ray source was more often used than the neutron source. However, fast neutron source is promising in such irradiation studies as it has many advantages, such as strong biological effect, high mutation rate, wide variation spectrum and stable mutant. Purpose: We aim to explore the method of dose calculation in pea samples. The biological effects of pea seeds (Pisum sativum L.) induced by different radioactive doses are to be investigated. Methods: The Needle Leaf Pea seeds were irradiated using 252Cf fission neutron source. The Monte Carlo simulation MCNP4C code was used to calculate the neutron absorbed doses and γ-rays (photons) absorbed doses in the samples. The biological effects of pea seeds induced by different radioactive doses were investigated. Results: The results showed that the flowering time of Ml generation peas was delayed with lower neutron absorbed doses (0.239-4.330 Gy), and the germination rate was promoted with micro-absorbed doses. The seedling branch rate of Ml generation peas was elevated by neutron radiation. The harvest of Ml generation was increased with appropriate neutron doses (0.619 Gy) irradiating peas. Conclusion: After being irradiated by low neutron doses (0.239-4.330 Gy), M1 generation peas show obvious biological effects. The research results have positive significance for the agricultural production and breeding. (authors)

  10. Study of neutron moderation using the {sup 241}Am-Be spectrum with hydrogenated materials; Estudo da moderacao de neutrons utilizando o espectro de {sup 241}Am-Be com materiais hidrogenados

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A.R.L.; Silva, F.S.; Martins, M.M.; Pereira, W.W., E-mail: aleiras@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ/LNMRI/LN), Rio de Janeiro, RJ (Brazil). Lab. de Neutrons; Freitas, B.M. [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Tavares, D.Y.S. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    This work intends to assess materials for moderation of neutrons, trying to reduce the rate of H{sub p}(10) and H⁎p(10), reducing the effective dose of Occupationally Exposed Workers (OEW) who handle this source daily. The neutron spectra moderated by different materials was performed with a neutron source of {sup 241}Am-Be in an electronic positioning system, using a neutron spectrometry with Bonner Sphere at 50 cm from the center of source. The materials used for moderation were paraffin, silicone and Polyvinyl Chloride (PVC) resin ball. (author)

  11. Multi-technique characterization of neutron fields from moderated 252Cf and 238PuBe sources

    International Nuclear Information System (INIS)

    At the Lawrence Livermore Laboratory, 252Cf and 238PuBe neutron sources are used for calibration of personnel neutron dose meters and neutron monitoring instrumentation. The sources with emission rates of approximately 2x109 and 2x107 n.s-1, respectively, have been calibrated by the United States National Bureau of Standards. The sources are transferred into a 815 m3 concrete calibration cell through a remotely operated pneumatic system. Calibrations can be made without source moderation, or with spherical moderators of aluminium, polyethylene, water or deuterium oxide placed over the end of the pneumatic irradiation tube. The source is located in the tube at one metre above a false floor in the centre of the cell. Nine different moderators are available in sizes up to 56 cm in diameter. Several techniques have been used to characterize the neutron fields produced by each source-moderator configuration to improve the quality of our calibrations. Measurements and calculations have been made to determine neutron flux, kerma rate, neutron spectrum, quality factor, dose equivalent rate and linear energy transfer (LET) spectrum. Neutron spectra are determined by: (1) Calibration using the ANISN discrete ordinates transport code, (2) Bonner sphere measurements using the LOUHI unfolding code, and (3) measurement with proton recoil counters and liquid scintillation detectors. The spectra are then folded into published energy dependent conversion factors to yield kerma, quality factor and dose equivalent values. We obtain LET spectra using a tissue-equivalent LET chamber and the GANDALF unfolding code. Chamber data are used to determine kerma and quality factor. Finally, an 80 cm3 tissue-equivalent ion chamber and neutron-insensitive Geiger counter are used to measure the neutron kerma. Results of the various techniques are presented and compared. In addition, comparisons are made with results obtained from conventional health physics instrumentation such as moderated rem

  12. Measurement of the neutron activity of a 252Cf source relative to the average number of prompt neutrons emitted per fission for the spontaneous fission

    International Nuclear Information System (INIS)

    A method was developed for measuring the absolute neutron activity of a large 252Cf source. The neutron counting assembly is composed of eight BF3 counters mounted in a large tank filled with water which is used as a moderator. The detection efficiency is determined using a low activity 252Cf source. The method is based on the identification of every fission event, followed by the counting of the fission neutrons detected by the BF3 counters during a time interval equal to the maximum neutron lifetime in the moderator. The efficiency is thus obtained relative to the average number of prompt neutrons emitted per 252Cf spontaneous fission which is commonly used as a standard. The measurement accuracy is estimated to be of the order of 1%

  13. Californium (252Cf) and its use as neutron source in science medicine and technology

    International Nuclear Information System (INIS)

    The application of radionuclides in science and nuclear techniques basically is related to unstable isotopes, which are produced from stable elements in nuclear reactor. Their specifications are various from view point of application . Using of physical and chemical properties of radionuclides in chemistry, for with marking the organic compounds we can exactly explain the mechanism of chemical reactions in medical, biology and bio-chemistry. In these cases the behaviour of radionuclides is very important and the selection of the suitable radionuclides is determined between the elements for investigation aims. The special specification of radio-nuclides analysis such as, half-life, kind of ray and energy should be considered with an special accuracy as well as the laws security regulations from view point of ray-protection should be completely observed mean time working these radio-nuclides. It should be considered that application of radio-isotopes is very important from their special specifications point of view. Applying the radionuclides from technology point of view in sciences and nuclear techniques aren't only limited to three analyses of α, β, and γ, but we can use the share of neutron which are produced from spli ting of heavy nucleus such as Californium252 as a neutron source in the depths of the sea and also determining the concentration of low quantity elements on moon and other spheres. The radioisotope of Californium252 is a neutron useful radiator for investigation in nuclear medical and technology because of automatically rapid split to 3.2% Californium252 radiates 1.34 * 109N/m in each mil/GH which suitable replacement for neutron sources based on (a, n) reaction, for example, Radium-Brellium or Amersium-Brellium. The energy distribution of radiated neutrons from analyzing of Californium252 like the spectrum of neutron which is produced from splitting of U235, Pu239 nucleus has the maximum energy in quantity, En=1 MeV in the range of 1.5 MeV. The

  14. Integral cross section measurements of a few threshold reactions induced by Am/Be neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, Md. Shuza; Hossain, Syed Mohammad; Rumman-Uz-Zaman, Md. [Atomic Energy Research Establishment, Dhaka (Bangladesh). Institute of Nuclear Science and Technology (INST); Spahn, Ingo; Qaim, Syed M. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Neurowissenschaften und Medizin (INM), Nuklearchemie (INM-5); Rakib-Uz-Zaman, Md. [Rajshahi Univ. (Bangladesh). Dept. of Applied Chemistry and Chemical Engineering

    2015-07-01

    Integral cross sections of the reactions {sup 46}Ti(n,p){sup 46}Sc, {sup 47}Ti(n,p){sup 47}Sc, {sup 48}Ti(n,p){sup 48}Sc, {sup 60}Ni(n,p){sup 60}Co and {sup 64}Zn(n,p){sup 64}Cu were measured with fast neutrons (E{sub n} > 1.5 MeV) from an Am/Be source. The results were compared with data calculated using the neutron spectral distribution and the excitation function of each reaction given in the data libraries ENDF/B-VII.0, IRDF-2002, JEFF-3.2 and JENDL-4.0. In general, the integral measurement and the integrated value agreed within ±4%, except for the {sup 46}Ti(n,p){sup 46}Sc reaction where JEFF-3.2 shows a deviation of 7% and the {sup 60}Ni(n,p){sup 60}Co reaction where ENDF/B-VII.0 and IRDF-2002 exhibit deviations upto 8%.

  15. Nuclear data measurements in 3x592 GBq 241Am-Be neutron cell

    International Nuclear Information System (INIS)

    The aim of this study is to present the results of the activities carried out within the scope of the Nuclear Data Measurements in 3x592 GBq Am-Be Neutron Cell project. The study covers the establishment of neutron irradiation systems, neutron and gamma dose rate evaluations in and around the laboratory, performance measurements of neutron irradiation systems, measurements of thermal, epithermal and fast neutron flux, gamma spectrometer efficiency calibrations, fast neutron fission product yield measurements for fertile nuclides (232Th and 238U), cross section measurements for fast neutron threshold detectors, gamma ray intensity measurements of the nuclides in uranium decay chain, elemental detection limit measurements and the half life measurement of short-lived isotopes. First of all, an irradiation geometry, which enables optimum irradiation, was designed for an irradiation system of 3 241Am-Be sources with 592 GBq activity each. Paraffin was chosen in order to slow down the source neutrons. An equilateral quadrangle with 70 cm side length and 60 cm height was used as paraffin moderator. Experimentally, it was determined that paraffin with approximately 3.5 cm thickness slows down to maximum thermal neutron flux of 241Am-Be neutrons. Paraffin block was placed on the base of the source room. In order to determine the positions of thermal and fast neutron irradiations, indium wires were irradiated with 5 mm intervals vertically parallel to the neutron sources in thermal and fast neutron irradiation cells. The position of maximum thermal and fast neutron fluxes is 61.5 cm for the thermal neutron irradiation cells and 69 cm for the fast neutron irradiation cell, from the top of the irradiation pipes down. One of the most important parameters of nuclear data measurements is the counting efficiency of the gamma spectrometer used for each counting geometry. For this reason, the detector efficiencies for the related counting geometries need to be measured accurately

  16. A comparative study on experimental and simulation responses of CR-39 to neutron spectra from a 252Cf source

    Directory of Open Access Journals (Sweden)

    Ghergherehchi Mitra

    2013-01-01

    Full Text Available A simulation of the interaction of neutrons emitted from a 252Cf source with a CR-39 detector is presented in this paper. Elastic and inelastic neutron interactions occur with the constituent materials of the CR-39 detector. Inelastic scatterings only consider (n, a and (n, p reactions. Fast neutrons tracks are, mainly, produced by recoil particle tracks in the plastic nuclear track detector as a result of the elastic scattering reaction of neutrons with the constituent materials of the solid-state nuclear track detectors, especially hydrogen nuclei. The energy of the neutron, incident position, direction, and type of interaction were sampled by the Monte Carlo method. The energy threshold, critical angle and scattering angle to the detector surface normal were the most important factors considered in our calculations. The energy deposited per neutron mass unit was calculated. The angular response was determined by both Monte Carlo simulation and experimental results. The number of visible proton tracks and energy deposited per neutron per visible track were calculated and simulated. The threshold energy of the recoil proton as a function of the thickness and incident proton angles was measured by the etchable range of protons at scattering angles, along with the shape and diameter of the track. Experimental and simulations result were in good agreement.

  17. Study of the applicability of the 252Cf neutron source for the determination of the concentration of disolved substances by means of π,α reactions

    International Nuclear Information System (INIS)

    For the determination of the interphase concentration for mass transfer in extraction systems α-particles generated by a n,α nuclear reaction are used. The study described tries to use 252Cf as a neutron source instead of the nuclear reactor previously used by Greger. The measuring technique is based on the generation of α particles and γ quanta by neutron irradiation of a phase containing 10B or 6Li compounds, the production of a sufficiently large number of α particles as well as the suppression of a high background of recoil protons still making difficulties at present. The particles generated are to be detected by means of liquid scintillation measuring technique and separated from each other by a pulse shaping analysis. In addition the design of a compact irradiation device is described allowing to perform measurements by means of a small 252Cf neutron source in a relatively modestly equipped isotope laboratory. In the set-up described in this paper the neutron source, unlike other, similar devices, is brought to the measuring position only during the period of measurement, using a pneumatic transport facility. The results obtained have shown that by using 252Cf as a neutron source for the method of measurement developed by Greger there are still no satisfactory results. (orig./RB)

  18. Characterization of the neutron field of the {sup 241}AmBe in a calibration room; Caracterizacion del campo de neutrones del {sup 241} AmBe en una sala para calibracion

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H.R. [UAZ, A.P. 336, 98000 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Universidad Politecnica de Madrid, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain)] e-mail: rvega@cantera.reduaz.mx

    2003-07-01

    The field of neutrons produced by an isotopic source of neutrons of {sup 241} Am Be had been characterized. The characterization was carried out modeling those relevant details of the calibration room and simulating the neutron transport at different distances of the source. The calculated spectra were used to determine the equivalent environmental dose rate. A series of experiments were carried out with the Bonner sphere spectrometric system to measure the spectra in the same points where the calculations were carried out and with these spectra the rates of environmental dose were calculated. By means of a one sphere dosemeter type Berthold the rates of environmental dose were measured. To the one to compare the calculated spectra and measured its were found small differences in the group of the thermal neutrons due to the elementary composition used during the simulation. When comparing the derived rates starting from the calculated spectra with those measured it was found a maxim difference smaller to 13%. (Author)

  19. Reactive ion beam etching of silicon with a new plasma ion source operated with CF4 : SiO2 over Si selectivity and Si surface modification

    OpenAIRE

    Lejeune, C.; Grandchamp, J.P.; Gilles, J.P.; Collard, E.; Scheiblin, P.

    1989-01-01

    Reactive Ion Beam Etching is obtained from a new specific ion gun, the Electrostatic Reflex Ion Source (Maxi-ERIS), which is operated with pure CF4 gas. The reported results concern both silicon dioxide and single-crystal silicon. They show that the operation of the source discharge down to its minimum pressure which implies an extensive fragmentation of the injected neutrals, provides a very convenient process for selective etching of SiO2 over Si, a basic problem in semiconductor technology...

  20. Results with the electron cyclotron resonance charge breeder for the 252Cf fission source project (Californium Rare Ion Breeder Upgrade) at Argonne Tandem Linac Accelerator System

    International Nuclear Information System (INIS)

    The construction of the Californium Rare Ion Breeder Upgrade, a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS), is nearing completion. The facility will use fission fragments from a 1 Ci 252Cf source; thermalized and collected into a low-energy particle beam by a helium gas catcher. In order to reaccelerate these beams, an existing ATLAS electron cyclotron resonance (ECR) ion source was redesigned to function as an ECR charge breeder. Thus far, the charge breeder has been tested with stable beams of rubidium and cesium achieving charge breeding efficiencies of 9.7% into 85Rb17+ and 2.9% into 133Cs20+.

  1. Determination of nuclear charge resolution of a thin film detector using a 252Cf fission fragment source

    International Nuclear Information System (INIS)

    Little quantitative information is available regarding the ability of a thin film detector (TFD) to determine the nuclear charge of a low energy heavy mass ion. To compare the nuclear charge resolving power Z/ΔZ of the TFD to other heavy ion detectors, an experiment was performed where the TFD luminescence response to 252Cf fission fragments was recorded in coincidence with the gamma de-excitation of the fragments. With this technique, the TFD nuclear charge resolving power Z/ΔZ was determined to be 25.2 for the light mass fragment group. (orig.)

  2. Determination of nuclear charge resolution of a thin film detector using a [sup 252]Cf fission fragment source

    Energy Technology Data Exchange (ETDEWEB)

    Milosevich, Z.; Muga, M.L. (Florida Univ., Gainesville, FL (United States). Dept. of Chemistry); Coldwell, R.L. (Florida Univ., Gainesville, FL (United States). Dept. of Physics)

    1992-09-15

    Little quantitative information is available regarding the ability of a thin film detector (TFD) to determine the nuclear charge of a low energy heavy mass ion. To compare the nuclear charge resolving power Z/[Delta]Z of the TFD to other heavy ion detectors, an experiment was performed where the TFD luminescence response to [sup 252]Cf fission fragments was recorded in coincidence with the gamma de-excitation of the fragments. With this technique, the TFD nuclear charge resolving power Z/[Delta]Z was determined to be 25.2 for the light mass fragment group. (orig.).

  3. 133Ba as a gamma-ray surrogate source for 1kg HEU and 10g 239Pu and 252Cf as a Neutron Surrogate for Pu

    International Nuclear Information System (INIS)

    Monte Carlo was performed for the purpose of relating gamma-ray signal strength from 1kg of HEU and 10g of 239Pu (as described in the ASTM standards) to the radiation emitted from an amount of 133Ba. A determination was made on the amount of 133Ba that could act as a surrogate for the specified amounts of HEU and Pu. 133Ba is not the ideal source to use as a surrogate for HEU because of its higher energies. 133Ba was chosen as the surrogate since it has a half-life of 10.54 years, rather then the more ideal surrogate of 57Co which has a half-life of 271 days. A similar Monte Carlo was performed for the purpose of relating neutron signal strength from 200g of Pu (as described in the ASTM standards) to the radiation emitted from an amount of shielded 252Cf. A determination was made on the amount of 252Cf necessary to act as a surrogate for the 200g of Pu. An ASTM standard source is a metallic sphere, cube, or right cylinder of SNM having maximum self-attenuation of its emitted radiation. For plutonium, the source should be at least 93% 239Pu, less than 6.5% 240Pu, and less than 0.5% impurities. A cadmium filter of at least 0.08cm thick should be used to reduce the impact of 241Am. For uranium, the source should contain at least 95% 235U and less than 0.25% impurities. For neutron detector testing, the neutron source shall be placed in a lead shielding container that reduces the gamma radiation from the source to 1% of its unshielded value

  4. Measurement of the ambient gamma dose equivalent and kerma from the small 252Cf source at 1 meter and the small 60Co source at 2 meters

    Energy Technology Data Exchange (ETDEWEB)

    Carl, W. F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-30

    NASA Langley Research Center requested a measurement and determination of the ambient gamma dose equivalent rate and kerma at 100 cm from the 252Cf source and determination of the ambient gamma dose equivalent rate and kerma at 200 cm from the 60Co source for the Radiation Budget Instrument Experiment (Rad-X). An Exradin A6 ion chamber with Shonka air-equivalent plastic walls in combination with a Supermax electrometer were used to measure the exposure rate and free-in-air kerma rate of the two sources at the requested distances. The measured gamma exposure, kerma, and dose equivalent rates are tabulated.

  5. Neutron gamma fraction imaging: Detection, location and identification of neutron sources

    International Nuclear Information System (INIS)

    In this paper imaging of neutron sources and identification and separation of a neutron source from another neutron source is described. The system is based upon organic liquid scintillator detector, tungsten collimator, bespoke fast digitiser and adjustable equatorial mount. Three environments have been investigated with this setup corresponding to an AmBe neutron source, a 252Cf neutron source and both sources together separated in space. In each case, events are detected, digitised, discriminated and radiation images plotted corresponding to the area investigated. The visualised neutron count distributions clearly locate the neutron source and, relative gamma to neutron (or neutron to gamma) fraction images aid in discriminating AmBe sources from 252Cf source. The measurements were performed in the low scatter facility of the National Physical Laboratory, Teddington, UK

  6. A fast neutron and dual-energy gamma-ray absorption method (NEUDEG) for investigating materials using a 252Cf source

    International Nuclear Information System (INIS)

    DEXA (dual-energy X-ray absorption) is widely used in airport scanners, industrial scanners and bone densitometers. DEXA determines the properties of materials by measuring the absorption differences of X-rays from a bremsstrahlung tube source with and without filtering. Filtering creates a beam with a higher mean energy, which causes lower material absorption. The absorption difference between measurements (those with a filter subtracted from those without a filter) is a positive number that increases with the effective atomic number of the material. In this paper, the concept of using a filter to create a dual beam and an absorption difference in materials is applied to radiation from a 252Cf source, called NEUDEG (neutron and dual-energy gamma absorption). NEUDEG includes absorptions for fast neutrons as well as the dual photon beams and thus an incentive for developing the method is that, unlike DEXA, it is inherently sensitive to the hydrogen content of materials. In this paper, a model for the absorption difference and absorption sum in NEUDEG is presented using the combined gamma ray and fast neutron mass attenuation coefficients. Absorption differences can be either positive or negative in NEUDEG, increasing with increases in the effective atomic number and decreasing with increases in the hydrogen content. Sample sets of absorption difference curves are calculated for materials with typical gamma-ray and fast neutron mass attenuation coefficients. The model, which uses tabulated mass attenuated coefficients, agrees with experimental data for porcelain tiles and polyethylene sheets. The effects of “beam hardening” are also investigated. - Highlights: • Creation of a dual neutron/gamma beam from 252Cf is described. • An absorption model is developed using mass attenuation coefficients. • A graphical method is used to show sample results from the model. • The model is successfully compared with experimental results. • The importance of

  7. Quantitative determination of 252Cf

    International Nuclear Information System (INIS)

    Sealed 252Cf sources in the microCurie to milliCurie range are routinely used in industry and research. At present, no reliable analytical method is available for precise determination of the activity. Very strong sources can be analyzed by neutron counting but the error is large. The authors propose to use gamma-ray spectroscopy for such analysis. In particular, high-energy gamma rays (above 1 MeV) of fission fragments in equilibrium with the source are very convenient because they have little absorption in materials surrounding the source. They have measured the gamma/alpha ratio for 252Cf with an uncertainty of better than 5%. The experiment involved the preparation of several thin 252Cf sources, alpha pulse height analysis, determination of alpha decay rate, and the measurement of gamma singles spectrum with a well shielded germanium spectrometer. The measured ratio and the gamma ray spectroscopy of unknown samples can provide the activity of 252Cf in these samples

  8. Quantitative determination of 252Cf

    International Nuclear Information System (INIS)

    Sealed 252Cf sources in the microCurie to milliCurie range are routinely used in industry and research. At present, no reliable analytical method is available for precise determination of the activity. Very strong sources can be analyzed by neutron counting but the error is large. We propose to use γ-ray spectroscopy for such analysis. In particular, high-energy γ rays (above 1 MeV) of fission fragments in equilibrium with the source are very convenient because they have little absorption in materials surrounding the source. It is found that the 1435.8-keV γ-ray of 138Cs and the 1596.5-keV γ-ray of 140La are well isolated and sufficiently above the background under these peaks. We have measured the γ/α ratio for the 252Cf with an uncertainty of better than 5%. The experiment involved the preparation of several thin 252Cf sources, alpha pulse height analysis, determination of α decay rate, and the measurement of γ singles spectrum with a well-shielded germanium spectrometer. The measured ratio and the γ-ray spectroscopy of unknown samples can provide the activity of 252Cf in these samples

  9. [The spectra of a laser-produced plasma source with CO2, O2 and CF4 liquid aerosol spray target].

    Science.gov (United States)

    Ni, Qi-Liang; Chen, Bo

    2008-11-01

    A laser-produced plasma (LPP) source with liquid aerosol spray target and nanosecond laser was developed, based on both soft X-ray radiation metrology and extreme ultraviolet projection lithography (EUVL). The LPP source is composed of a stainless steel solenoid valve whose temperature can be continuously controlled, a Nd : YAG laser with pulse width, working wavelength and pulse energy being 7 ns, 1.064 microm and 1J respectively, and a pulse generator which can synchronously control the valve and the laser. A standard General Valve Corporation series 99 stainless steel solenoid valve with copper gasket seals and a Kel-F poppet are used in order to minimize leakage and poppet deformation during high-pressure cryogenic operation. A close fitting copper cooling jacket surrounds the valve body. The jacket clamps a copper coolant carrying tube 3 mm in diameter, which is fed by an automatically pressurized liquid nitrogen-filled dewar. The valve temperature can be controlled between 77 and 473 K. For sufficiently high backing pressure and low temperature, the valve reservoir gas can undergo a gas-to-liquid phase transition. Upon valve pulsing, the liquid is ejected into a vacuum and breaks up into droplets, which is called liquid aerosol spray target. For the above-mentioned LPP source, firstly, by the use of Cowan program on the basis of non-relativistic quantum mechanics, the authors computed the radiative transition wavelengths and probabilities in soft X-ray region for O4+, O5+, O6+, O7+, F5+, F6+ and F7+ ions which were correspondingly produced from the interaction of the 10(11)-10(12) W x cm(-2) power laser with liquid O2, CO2 and CF4 aerosol spray targets. Secondly, the authors measured the spectra of liquid O2, CO2 and CF4 aerosol spray target LPP sources in the 6-20 nm band for the 8 x 10(11) W x cm(-2) laser irradiance. The measured results were compared with the Cowan calculated results ones, and the radiative transition wavelength and probability for the

  10. Efficiency of a 252Cf source in normal or in B-10 enriched lymphocytes evaluated by SCGE assay, classical cytogenetics and FISH technique

    International Nuclear Information System (INIS)

    Biological effectiveness of a californium-252 source was evaluated after irradiations in vitro of normal or pretreated cells with compound enriched in the B-10 ion (Na211B12H11SH also known as BSH) in order to check the possibility of any enhancement effect due to the process of boron neutron capture. Peripheral blood lymphocytes were used as a model for human cells. Human blood samples or isolated lymphocytes were irradiated with the isotopic source of 252Cf, at the Faculty of physics and Nuclear Techniques at the University of Mining and Metallurgy, Cracow (both the neutron source and the samples were placed in ''infinite'' polyethylene block). DNA and chromosomal damage were studied to compare the biological effectiveness of irradiation. Single cell gel electrophoresis also known as the Comet assay was done to investigate the DNA damage. Classical cytogenetic analysis was applied to assess the frequencies of unstable aberrations (dicentrics, rings and acentric fragments). To evaluate the frequencies of stable aberrations the fluorescence in situ hybridization (FISH) with probes for chromosomes 1, 4 (14.3% of the whole genome) was performed. Linear (or close to linear ) increases with radiation doses were observed for the DNA damage and aberration frequencies in lymphocytes both untreated or pretreated with BSH. Levels of translocations evaluated for the whole genome were comparable with the frequencies of dicentrics and rings. No significant differences were detected due to radiation dose in the frequencies of sister chromatid exchanges (SCE) detected in the second mitosis. Statistically no significant differences were observed in various biological end-points between normal or boron pre-treated cells. (author)

  11. Thermal neutron imaging with rare-earth-ion-doped LiCaAlF{sub 6} scintillators and a sealed {sup 252}Cf source

    Energy Technology Data Exchange (ETDEWEB)

    Kawaguchi, Noriaki, E-mail: famicom@mail.tagen.tohoku.ac.jp [Tokuyama Corporation, Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yanagida, Takayuki; Fujimoto, Yutaka; Yokota, Yuui; Kamada, Kei [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Fukuda, Kentaro; Suyama, Toshihisa [Tokuyama Corporation, Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Watanabe, Kenichi; Yamazaki, Atsushi [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Chani, Valery [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan)

    2011-10-01

    Thermal neutron imaging with Ce-doped LiCaAlF{sub 6} crystals has been performed. The prototype of the neutron imager using a Ce-doped LiCaAlF{sub 6} scintillating crystal and a position sensitive photomultiplier tube (PSPMT) which had 64 multi-channel anode was developed. The Ce-doped LiCaAlF{sub 6} single crystal was grown by the Czochralski method. A plate with dimensions of a diameter of 50x2 mm{sup 2} was cut from the grown crystal, polished, and optically coupled to PSPMT by silicone grease. The {sup 252}Cf source (<1 MBq) was sealed with 43 mm of polyethylene for neutron thermalization. Alphabet-shaped Cd pieces with a thickness of 2 mm were used as a mask for the thermal neutrons. After corrections for the pedestals and gain of each pixel, we successfully obtained two-dimensional neutron images using Ce-doped LiCaAlF{sub 6}.

  12. 利用示踪252Cf中子源的材料鉴别技术%Material Recognition by Using 252Cf Source

    Institute of Scientific and Technical Information of China (English)

    郝昕; L. Sajo-Bohus; 竺礼华; L. Stevanato; D. Fabris; M. Lunardon; S. Moretto; G. Nebbia; S. Pesente; G. Viesti

    2011-01-01

    Non-destructive assay of parcels using a tagged 252Cf source and time of flight technique was studied.The method of material recognition was achieved by measuring simultaneously the transmission of neutron and gamma ray to determine the average atomic number.The automatic tomography was realized with the movement of motors and autostart of the digital acquisition system.With the calibration of the detectors, the average atomic number for each pixel of the sample was determined which allows one to recognize material with this method.%本文叙述了利用252Cf裂变中子源结合飞行时间技术对包裹进行无损检测的可行性研究,通过联合测量中子和伽玛射线的吸收谱确定样品的平均原子序数,完成被测材料的鉴定.实验采用自发裂变的252Cf中子源作为白中子源和伽马射线源,用塑料闪烁探测器探测中子和伽马射线.通过LabVIEW程序控制步进电机运动并整合获取的实验数据,实现了待测样品断层扫描数据采集工作的自动化.在对闪烁探测器进行能量和时间刻度后,对几种典型材料组成的样品进行实验分析,采集数据重建其分布图像,确认了用这项技术对材料无损检测的可行性.

  13. VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON- IDEALITY, AND CRITICAL PROPERTIES OF CF3OCF2CF2CF3, c-CF2CF2CF2CF2O, CF3OCF2OCF3, AND CF3OCF2CF2H

    Science.gov (United States)

    New measurements of the thermophysical properties of CF3OCF2CF2CF3 and c -CF2CF2CF2CF2O are reported from T ≈ 235 K to the critical region. Liquid-phase volumetric results for CF3OCF2OCF3 and CF3OCF2CF2H (235 < T/K < 303) are reported to supplement the information already availab...

  14. Atmospheric chemistry of CF3OCF2CF2H and CF3OC(CF3)2H

    DEFF Research Database (Denmark)

    Andersen, Mads Peter Sulbæk; Nielsen, O J; Wallington, T J;

    2005-01-01

    gives CF3OC(O)CF3 and COF2 in molar yields that are indistinguishable from 100%. Quantitative infrared spectra were recorded and used to estimate global warming potentials of 3690 and 8230 (100 year time horizon, relative to CO2) for CF3OCF2CF2H and CF3OC(CF3)2H, respectively. All experiments were...

  15. Results of intercomparison of primary calibration standards for radionuclide source neutron emission

    International Nuclear Information System (INIS)

    UVVVR possesses a so-called manganese bath, i.e., a primary calibration standard for radionuclide neutron sources. The manganese bath assembly was tested in 1982 and in 1988 and compared with calibration standards of other metrological institutes. In 1982, Am-Be and 252Cf sources were tested in ASMW (DD), UVVVR (CS), VNIIM (SU) and RI (SU), in 1988, the 252Cf comparison involved UVVVR, VNIIM and NLMII (BG). The results of comparisons are tabulated. (E.J.). 3 tabs., 3 refs

  16. Estudio de la anisotropía de una fuente de Am-Be de 111 GBq

    OpenAIRE

    Méndez Villafañe, Roberto; Gallego Díaz, Eduardo F.; Lorente Fillol, Alfredo; Ibáñez, Sviatovslav; Guerrero Araque, Jorge Enrique

    2011-01-01

    Se ha estudiado la anisotropía de una fuente de Am-Be de 111 GBq (3Ci) mediante el uso de un pequeño motor que permite girar paso a paso la fuente situada en su posición de irradiación habitual. Las medidas se han realizado con un contador proporcional de 3He alojado en el interior de una esfera moderadora de 8” correspondiente a un sistema de espectrometría de esferas Bonner. Se reportan los resultados obtenidos y el factor de anisotropía determinado para esta fuente.

  17. The U.S. Department of Energy 252Cf program

    International Nuclear Information System (INIS)

    Soon after the discovery of the 252Cf radioisotope in 1952, researchers realized its potential as a spontaneous source of neutrons. Under the guidance of the Atomic Energy Commission, the Savannah River Laboratory (SRL) undertook an ambitious market evaluation and source fabrication program in the 1960s. Routine production of 252Cf was initiated at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL), initially from plutonium oxide target rods and ultimately from more productive recycle curium oxide target rods. The 252Cf radioisotope was then shipped to SRL for incorporation into a variety of SRL-designed sources for industrial, medical, and research applications. ORNL independently developed another line of sources, primarily for research applications. Industrial source fabrication operations were consolidated at ORNL in 1986. In 1992, SRL fabricated its last 252Cf sources. Today, most of the world's supply of 252Cf is processed, purified, and encapsulated for shipment at the Radiochemical Engineering Development Center (REDC) of ORNL

  18. A new perfluorinated peroxynitrate, CF3CF2CF2CF2OONO2. Synthesis, characterization and atmospheric implications

    Science.gov (United States)

    Bossolasco, Adriana G.; Vila, Jesús A.; Burgos Paci, Maxi A.; Malanca, Fabio E.; Argüello, Gustavo A.

    2014-09-01

    CF3CF2CF2CF2OONO2 was synthesized from the photolysis of CF3CF2CF2CF2I, in presence of NO2 and O2. Alkyl peroxynitrates (CxF2x+1OONO2) could be formed in the atmospheric degradation of chlorofluorocarbons, hydrofluorocarbons and hydrofluoroethers. We present here the synthesis and characterization (IR and UV absorption cross sections) of CF3CF2CF2CF2OONO2 and its comparison with those corresponding to other perfluoro alkyl peroxynitrates. The thermal stability was studied as a function of total pressure (from 9.0 to 417 mbar) and temperature (from 283 to 293 K) using infrared spectroscopy. Kinetic parameters measured for the thermal dissociation were Ea = (81 ± 4) kJ/mol and A = 4.8 × 1012. DFT calculations at the B3LYP/6-311+G∗ level were used to explore the ground state potential energy surface. Geometrical parameters, conformer populations and vibrational spectra are presented. The calculated activation energy was 81.3 kJ mol-1 in excellent agreement with experimental results. Atmospheric implications are discussed.

  19. Neutron sources and its dosimetric characteristics

    International Nuclear Information System (INIS)

    By means of Monte Carlo methods the spectra of the produced neutrons 252 Cf, 252 Cf/D2O, 241 Am Be, 239 Pu Be, 140 La Be, 239 Pu18O2 and 226 Ra Be have been calculated. With the information of the spectrum it was calculated the average energy of the neutrons of each source. By means of the fluence coefficients to dose it was determined, for each one of the studied sources, the fluence factors to dose. The calculated doses were H, H*(10), Hp,sIab (10, 00), EAP and EISO. During the phase of the calculations the sources were modeled as punctual and their characteristics were determined to 100 cm in the hole. Also, for the case of the sources of 239 Pu Be and 241 Am Be, were carried out calculations modeling the sources with their respective characteristics and the dosimetric properties were determined in a space full with air. The results of this last phase of the calculations were compared with the experimental results obtained for both sources. (Author)

  20. Characterization of an Am-Be PGNAA set-up developed for in situ liquid analysis: Application to domestic waste water and industrial liquid effluents analysis

    Energy Technology Data Exchange (ETDEWEB)

    Idiri, Z., E-mail: zmidiri@yahoo.f [Centre de Recherche Nucleaire d' Alger, 02 Bd Frantz Fanon, B.P399, Alger-Gare (Algeria); Mazrou, H. [Centre de Recherche Nucleaire d' Alger, 02 Bd Frantz Fanon, B.P399, Alger-Gare (Algeria); Amokrane, A. [Universite des Sciences et de la Technologie Houari Boumediene, Alger (Algeria); Bedek, S. [Centre de Recherche Nucleaire d' Alger, 02 Bd Frantz Fanon, B.P399, Alger-Gare (Algeria)

    2010-01-15

    A prompt gamma neutron activation analysis (PGNAA) set-up with an Am-Be source developed for in situ analysis of liquid samples is described. The linearity of its response was tested for chlorine and cadmium dissolved in water. Prompt gamma efficiency of the system has been determined experimentally using prompt gamma of chlorine dissolved in water and detection limits for different elements have been derived for domestic waste water. A methodology to analyze any kind of liquid is then proposed. This methodology consists mainly on using standards with water as bulk or in the case of absolute method, to use gamma efficiency determined with prompt gammas emitted by chlorine dissolved in water. To take into account the thermal neutron flux variations inside the samples, flux monitoring was carried out using a He-3 neutron detector placed at the external sample container surface. Finally, to correct for the differences in gamma attenuation, average gamma attenuations factors were calculated using MCNP5 code. This method was then checked successfully by determining cadmium in industrial phosphoric acid and our result was in good agreement with that obtained with inductively coupled plasma (ICP) method.

  1. Characterization of an Am-Be PGNAA set-up developed for in situ liquid analysis: Application to domestic waste water and industrial liquid effluents analysis

    Science.gov (United States)

    Idiri, Z.; Mazrou, H.; Amokrane, A.; Bedek, S.

    2010-01-01

    A prompt gamma neutron activation analysis (PGNAA) set-up with an Am-Be source developed for in situ analysis of liquid samples is described. The linearity of its response was tested for chlorine and cadmium dissolved in water. Prompt gamma efficiency of the system has been determined experimentally using prompt gamma of chlorine dissolved in water and detection limits for different elements have been derived for domestic waste water. A methodology to analyze any kind of liquid is then proposed. This methodology consists mainly on using standards with water as bulk or in the case of absolute method, to use gamma efficiency determined with prompt gammas emitted by chlorine dissolved in water. To take into account the thermal neutron flux variations inside the samples, flux monitoring was carried out using a He-3 neutron detector placed at the external sample container surface. Finally, to correct for the differences in gamma attenuation, average gamma attenuations factors were calculated using MCNP5 code. This method was then checked successfully by determining cadmium in industrial phosphoric acid and our result was in good agreement with that obtained with inductively coupled plasma (ICP) method.

  2. 252Cf encapsulation and shipping at SRL

    International Nuclear Information System (INIS)

    Techniques were developed at the Savannah River Laboratory to encapsulate 252Cf sources for research and for medical and industrial applications. The sources are for sale or loan under the USAEC market evaluation program. A new facility is described which limits radiation exposure rates to less than mrem/h in normally occupied areas, except for short periods when maximum amounts of up to 100 mg of 252Cf may be handled. Sources as large as 10 mg have been made in this facility. The entire complex is surrounded by up to 48 in. of gamma and neutron shielding. Equipment was designed for remote handling, assembly, and examination of microliter quantities of solutions and capsule components as small as 1/8-in. cylinders. Special equipment, procedures, and carriers are described for safe, practical handling, storage, and shipment of encapsulated 252Cf. Brief descriptions and photographs of six casks most commonly used for transporting quantities ranging from 100 μg to 50 mg of 252Cf are included. (U.S.)

  3. VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON- IDEALITIES, AND CRITICAL PROPERTIES OF SOME FLUORINATED ETHERS: CF3OCF2OCF3, CF3OCF2 CF2H, c-CF2CF2CF2O, CF3OCF2H, AND CF3OCH3; AND OF CCl3F AND CF2ClH

    Science.gov (United States)

    Vapor pressures, compressibilities, expansivities, and molar volumes of the liquid phase have been measured between room temperature and the critical temperature for a series of fluorinated ethers: CF3OCF2OCF3, CF3OCF2CF2H, c-CF2CF2CF2O, CF3OCF2H, and CF3OCH3. Vapor-phase non-ide...

  4. Xe-135 Production from Cf-252

    Energy Technology Data Exchange (ETDEWEB)

    C. A. McGrath; T. P. Houghton; J. K. Pfeiffer; R. K. Hague

    2012-03-01

    135Xe is a good indicator that fission has occurred and is a valuable isotope that helps enforce the Comprehensive Test Ban Treaty. Due to its rather short half life and minimal commercial interest, there are no known sources where 135Xe can be purchased. Readily available standards of this isotope for calibrating collection and analytical techniques would be very useful. 135Xe can be produced in the fissioning of actinide isotopes, or by neutron capture on 134Xe. Since the neutron capture cross section of 134Xe is 3 mB, neutron capture is a low yield, though potentially useful, production route. 135Xe is also produced by spontaneous fission of 252Cf. 252Cf has a spontaneous fission rate of about 6 x 1011 s-1g-1. The cumulative yield from the spontaneous fission of 252Cf is 4.19%; and the competing neutron capture reaction that depletes 135Xe in thermal reactor systems is negligible because the neutron capture cross-section is low for fast fission neutrons. At the INL, scientists have previously transported fission products from an electroplated 252Cf thin source for the measurement of nuclear data of short-lived fission products using a technique called He-Jet collection. We have applied a similar system to the collection of gaseous 135Xe, in order to produce valuable standards of this isotope.

  5. Mass spectrometric measurements in inductively coupled CF4/Ar plasmas

    International Nuclear Information System (INIS)

    Positive ion fluxes, mean ion energies and ion energy distribution functions in low pressure CF4/Ar plasmas have been measured. The experiments were conducted in a Gaseous Electronics Conference cell using an inductively coupled plasma device powered by a 13.56 MHz radiofrequency (rf) power source. The measurements were made at 200 and 300 W of input rf power and at 10, 20, 30 and 50 mTorr gas pressures for three gas mixtures: (i) 20% CF4 : 80% Ar, (ii) 50% CF4 : 50% Ar and (iii) 80% CF4 : 20% Ar. A Langmuir probe was also used to measure plasma parameters such as ne, ni+ and electron energy distribution functions (EEDF) which were subsequently used to reconcile the mass spectrometer data. CF3+ is the most dominant fluorocarbon ion product of the plasma, followed by CF2+ and CF+. Ar+ is also detected in significant amounts with its relative flux increasing with the increase in Ar content in the gas mixture. Significant amounts of etch products, SiFx+/COF+x (x = 0-3), of the quartz window were also detected. The fluorocarbon ions are produced by direct electron impact and by ion-molecule reactions between Ar+ and CF4 as well as between CF3+ and CF4. However, the concentrations of CF2+ and CF+ are much larger than that which can be possibly produced from these two processes. The available cross-section data suggest that the direct electron impact ionization of the fragment neutrals and negative ion production by electron attachment may be responsible for the increase in the concentrations of the minor ions. F- densities, estimated by using the measured EEDF and positive ion flux data and the available cross-section data, agree well with the published experimental data

  6. Use of neutron activation and X-ray fluorescence with radioactive sources (Cf-252 and Am-241) for the instrumental qualiquantitative simultaneous analysis of some elements in samples of mineral supplement for animals

    International Nuclear Information System (INIS)

    To study the possibility of using two non-destructive (neutron activation and X-ray fluorescence) analyses in simultaneous quali-quantitative evaluations of some elements in mineral supplement for animals, a Cf-252 neutron source (11.3 mCi; 21.1 μgrams) and a Am-241 low energy gamma-ray emitter source (59.5 KeV; 100 mCi) were employed. For these sources, shieldings and sample irradiation systems were built. For the neutron activation analysis a reservoir of 72 cm height and 43 cm diameter was filled with paraffine, and the samples and neutron sources were put inside this reservoir using polypropilene and nylon tubes. To detect the gamma-rays emitted by the radioisotopes a well-type solid NaI(Tl) crystal scintillator (3x3') was used, coupled to a multi-channel analyser. For the X-ray fluorescence analysis a lead cylinder of 9.75 cm height and 5.6 cm diameter (with 0.7 cm thickness) was made and internally lined with a 0.36 mm copper and 0.1 mm aluminium foil. (Author)

  7. Simulation study of neutrons time-correlated coincidence count for uranium components based on 252Cf source-driven noise analysis method

    International Nuclear Information System (INIS)

    Background: For the intensity of high-enriched uranium's neutrons from fission is weak, the active detection method is commonly adopted. Purpose: The quality attribute of uranium components is analysed. Methods: According to the theory of neutron source-driven noise analysis method and mass measurement problem of uranium material or uranium component, Monte Carlo simulation is used to study the mass measurement of metal uranium sphere components with the same geometry and enrichment and the different masses. The time-correlation coincidence count distributions to different uranium components are obtained. Results: The source-driven time correlation coincidence measurements can provide quantities, time-dependent coincidence distributions between two detectors, which can be related to the mass of uranium components. Conclusions: By studying on the sample (radius: 4.67 cm, mass: 8 kg), it realized mass measurement to metal uranium sphere components with different masses. (authors)

  8. Advancing netCDF-CF for the Geoscience Community

    Science.gov (United States)

    Davis, Ethan; Zender, Charlie; Arctur, David; Jelenak, Aleksandar; Santek, Dave; O'Brien, Kevin; Dixon, Mike

    2016-04-01

    The Climate and Forecast (CF) metadata conventions for netCDF (netCDF-CF) are used widely by weather forecasters, climate scientists, and remote-sensing researchers to include auxiliary information along with scientific data. This auxiliary information, or metadata, describes where and how the data were collected, the units of measurement used, and other similar details. Numerous open source and commercial software tools are able to explore and analyze data sets that include netCDF-CF metadata. This presentation will introduce work to extend the existing netCDF-CF metadata conventions in ways that will broaden the range of earth science domains whose data can be represented. It will include discussion of the enhancements to netCDF-CF that are envisioned and information on how to participate in the community-based standards development process.

  9. Experimental evaluation of the neutrons flux of a irradiator with AmBe sources and its possibility of use in materials analysis

    International Nuclear Information System (INIS)

    This work had as a target to determine the irradiator thermal and over cadmium (epithermal and fast) neutrons flux , of the Nuclear Experimental Laboratory of the Nuclear Energy Center (CNEN) - IPEN, and the possibility of its use for Neutron Activation Analysis (NAA) by the absolute method. The neutrons flux quantification was performed indirectly by the gold naked and cadmium-covered foils activation technique. The neutrons flux was determined for two situations: with polyethylene block 5.0 cm thick and without the polyethylene block. The quantification of the elements present in the irradiated samples was obtained after the experimental determination of the incident neutrons flux in the irradiation position of the sample. Flux values along the irradiator axis were determined. Some materials were analyzed, presenting good agreement with reference values. (author)

  10. Fast Neutron Imaging Using 241Am-Be Neutron Source%241Am-Be中子源快中子成像研究

    Institute of Scientific and Technical Information of China (English)

    蒋诗平; 陈亮; 万里飚; 杜淮江; 范扬眉; 韩荣典

    2007-01-01

    中子成像是一种与X射线成像互补的无损探测技术.为探索同位素中子源用于发展可移动的无损检测系统,利用241Am-Be作为中子源,使用自制的中子发光转换屏和X射线胶片作为探测系统开展了快中子成像研究,并获得了较高质量的图像.研究结果表明,利用241Am-Be中子源发展小型探测系统是有潜力的.

  11. Dating groundwater with trifluoromethyl sulfurpentafluoride (SF 5CF3), sulfur hexafluoride (SF6), CF 3Cl (CFC-13), and CF2Cl2 (CFC-12)

    Science.gov (United States)

    Busenberg, E.; Plummer, L.N.

    2008-01-01

    [1] A new groundwater dating procedure using the transient atmospheric signal of the environmental tracers SF5CF3, CFC-13, SF6, and CFC-12 was developed. The analytical procedure determines concentrations of the four tracers in air and water samples. SF 5CF3 and CFC-13 can be used to date groundwaters in some environments where the CFCs and SF6 have previously failed because these new tracers have increasing atmospheric input functions, no known terrigenic source, and are believed to be stable under reducing conditions. SF5CF3 has a dating range from 1970 to modern; the mixing ratio (mole fraction) in North American air has increased from the detection limit of 0.005 parts per trillion (ppt) to the 2006 mole fraction of about 0.16 ppt. No evidence was found for degradation of SF5CF3 in laboratory anaerobic systems. The solubility of SF5CF3 was measured in water from 1 to 35??C. Groundwater samples that contained large amounts of terrigenic SF6 did not contain terrigenic SF 5CF3. CFC-13 is a trace atmospheric gas with a dating range in groundwater of about 1965 to modem. CFC-13 has been used primarily in very low-temperature refrigeration; thus groundwater environments are less likely to be contaminated with nonatmospheric sources as compared to other widely used CFCs. Because of the low solubility of SF5CF3 and CFC-13 in water, an excess air correction must be applied to the apparent ages. The new dating procedure was tested in water samples from wells and springs from Maryland, Virginia, and West Virginia.

  12. Adsorption of CF4 on graphite preplated with a monolayer of CF3Cl

    Science.gov (United States)

    Thomas, Petros; Velazquez, Daniel; Hess, George B.

    2011-03-01

    We report a study of the adsorption of CF4 on graphite preplated with a monolayer of CF3Cl, using infrared reflection absorption spectroscopy combined with ellipsometry. The saturated vapor pressure of CF3Cl is nearly 3 orders of magnitude smaller than that of CF4 at the same temperature, so the main control variables are the temperature and the pressure (or chemical potential) of CF4, together with the initial coverage of CF3Cl. The temperature range covered is 60-105 K. We find that, if the initial monolayer of CF3Cl is liquid, CF4 continuously displaces CF3Cl by substitution in the monolayer. If the initial monolayer of CF3Cl is solid, due to either lower temperature or compression, CF4 condenses as a second layer on the top of the CF3Cl layer, with only slight mixing with the original layer. This behavior persists to multiple layers of CF4.

  13. The comparison of four neutron sources for Prompt Gamma Neutron Activation Analysis (PGNAA) in vivo detections of boron

    International Nuclear Information System (INIS)

    A Prompt Gamma Ray Neutron Activation Analysis (PGNAA) system, incorporating an isotopic neutron source has been simulated using the MCNPX Monte Carlo code. In order to improve the signal to noise ratio different collimators and a filter were placed between the neutron source and the object. The effect of the positioning of the neutron beam and the detector relative to the object has been studied. In this work the optimisation procedure is demonstrated for boron. Monte Carlo calculations were carried out to compare the performance of the proposed PGNAA system using four different neutron sources (241Am/Be, 252Cf, 241Am/B, and DT neutron generator). Among the different systems the 252Cf neutron based PGNAA system has the best performance. (author)

  14. Cystic Fibrosis (CF) Respiratory Screen: Sputum

    Science.gov (United States)

    ... Tropical Delight: Melon Smoothie Pregnant? Your Baby's Growth Cystic Fibrosis (CF) Respiratory Screen: Sputum KidsHealth > For Parents > Cystic Fibrosis (CF) Respiratory Screen: Sputum Print A A A ...

  15. Investigation and optimisation of mobile NaI(Tl) and 3He-based neutron detectors for finding point sources

    International Nuclear Information System (INIS)

    Neutron radiation produces high-energy gamma radiation through (n,γ) reactions in matter. This can be used to detect neutron sources indirectly using gamma spectrometers. The sensitivity of a gamma spectrometer to neutrons can be amplified by surrounding it with polyvinyl chloride (PVC). The hydrogen in the PVC acts as a moderator and the chlorine emits prompt gammas when a neutron is captured. A 4.7-l 3He-based mobile neutron detector was compared to a 4-l NaI(Tl)-detector covered with PVC using this principle. Methods were also developed to optimise the measurement parameters of the systems. The detector systems were compared with regard to their ability to find 241AmBe, 252Cf and 238Pu–13C neutron sources. Results from stationary measurements were used to calculate optimal integration times as well as minimum detectable neutron emission rates. It was found that the 3He-based detector was more sensitive to 252Cf sources whereas the NaI(Tl) detector was more sensitive to 241AmBe and 238Pu–13C sources. The results also indicated that the sensitivity of the detectors to sources at known distances could theoretically be improved by 60% by changing from fixed integration times to list mode in mobile surveys

  16. Xe-135 production from Cf-252

    International Nuclear Information System (INIS)

    The presence of 135Xe is often used as an indicator that fission has occurred, and is used to help enforce the Comprehensive Test Ban Treaty. There are no known commercial suppliers, though it can be acquired. Readily available standards of this isotope are very useful. 135Xe can be produced through fission, or by neutron capture on 134Xe. At the INL, scientists have previously transported fission products from an electroplated 252Cf thin source for the measurement of nuclear data of short-lived fission products using a technique called He-Jet collection. A similar system has been applied to the collection of gaseous 135Xe, and 133Xe, in order to produce standards of these isotopes. (author)

  17. Spectrum of isotopic neutron sources inside concrete wall spherical cavities

    International Nuclear Information System (INIS)

    The neutron spectra of 252Cf/D2O, 140LaBe, 252Cf, 238Pu18O2, 241AmB, 241AmBe, 226RaBe and 239PuBe isotopic neutron sources due to room-return have been determined for various source-to-detector distances in concrete spherical cavities of different radius. Changes in the amount of thermal neutrons (E≤0.414eV) were analyzed to estimate, for each neutron source, the coefficient that relates the neutron source strength and room surface area with the thermal neutron fluence rates. The study was carried out using Monte Carlo methods for 200, 400, 500, 800, 1000, 1200 and 1500-cm-radius spherical cavity in vacuum; cavities are 100-cm-thick concrete. Point sources were located at the center of cavity and neutron spectra were calculated at several source-to-detector distances along the cavity radius. The thermal neutron contribution was thereby evaluated. From these calculations a weighted coefficient value that relates the thermal neutron fluence with the neutron source strength and the total inner area surface of the cavity was estimated to be 3.76±0.03

  18. A pneumatic transfer system for special form 252Cf

    International Nuclear Information System (INIS)

    A pneumatic transfer system has been developed for use with series 100 Special Form 252Cf. It was developed to reduce the exposure to personnel handling sources of 252Cf with masses up to 150 microg by permitting remotely activated two-way transfer between the storage container and the irradiation position. The pneumatic transfer system also permits transfers for reproducible repetitive irradiation periods. In addition to the storage container equipped with quick-release fittings, the transfer system consists of an irradiation station, a control box with momentary contact switches to activate the air-pressure control valves and indicators to identify the location of the source, and connecting air hose and electrical wire. A source of 20 psig air and 110 volt electrical power are required for operation of the transfer system which can be easily moved and set up by one individual in 5 to 10 minutes. Tests have shown that rarely does a source become lodged in the transfer tubing, but two methods have been developed to handle incomplete transfers of the 252Cf source. The first method consists of closing one air vent to allow a pressure impulse to propel the source to the opposite side. The second method applies to those 252Cf capsules with a threaded or tapped end to which a small ferromagnetic piece can be attached; an incompletely transferred source in the transfer tube can then be guided to a position of safety by surrounding the transfer tubing containing the capsule with a horseshoe magnet attached to the end of a long pole

  19. Investigation of the characteristics of 252Cf-detectors

    International Nuclear Information System (INIS)

    In the first chapter the characteristic behaviors of two Cf detectors have been investigated by performing pilot measurements. The detector with the stronger source gives an unstable signal with a low signal/noise ratio. Therefore this detector has not been further investigated. The ionization chamber reacts on both fission products and alpha decay. An energy experiment showed that there were large difficulties to separate those decays. A plastic scintillator, which reacts on both photons and neutrons, was used for neutron detection. Energy spectrums were performed and the result showed that it is difficult to set an energy threshold to separate the neutrons and the photons. The discrimination will rather be achieved by time of flight methods which is discussed under the second chapter in this thesis; Experimental results. An other experiment was done in order to investigate whether it is possible to detect any delayed components from the spontaneous fission of Cf. The result showed that delayed components existed. Either they are delayed neutrons from exited fission products, or it is some delay related to the charge collection in the Cf detector. Correlation measurements showed that few events are coincident. Only 50% of the signals from the plastic scintillator are correlated with the Cf source

  20. First detection of CF+ towards a high-mass protostar

    CERN Document Server

    Fechtenbaum, S; Schneider, N; Csengeri, T; Duarte-Cabral, A; Herpin, F; Lefloch, B

    2015-01-01

    We report the first detection of the J = 1 - 0 (102.6 GHz) rotational lines of CF+ (fluoromethylidynium ion) towards CygX-N63, a young and massive protostar of the Cygnus X region. This detection occurred as part of an unbiased spectral survey of this object in the 0.8-3 mm range, performed with the IRAM 30m telescope. The data were analyzed using a local thermodynamical equilibrium model (LTE model) and a population diagram in order to derive the column density. The line velocity (-4 km s-1) and line width (1.6 km s-1) indicate an origin from the collapsing envelope of the protostar. We obtain a CF+ column density of 4.10e11 cm-2. The CF+ ion is thought to be a good tracer for C+ and assuming a ratio of 10e-6 for CF+/C+, we derive a total number of C+ of 1.2x10e53 within the beam. There is no evidence of carbon ionization caused by an exterior source of UV photons suggesting that the protostar itself is the source of ionization. Ionization from the protostellar photosphere is not efficient enough. In contras...

  1. Investigation of the characteristics of {sup 252}Cf-detectors

    Energy Technology Data Exchange (ETDEWEB)

    Karlsson, Erik

    2004-12-01

    In the first chapter the characteristic behaviors of two Cf detectors have been investigated by performing pilot measurements. The detector with the stronger source gives an unstable signal with a low signal/noise ratio. Therefore this detector has not been further investigated. The ionization chamber reacts on both fission products and alpha decay. An energy experiment showed that there were large difficulties to separate those decays. A plastic scintillator, which reacts on both photons and neutrons, was used for neutron detection. Energy spectrums were performed and the result showed that it is difficult to set an energy threshold to separate the neutrons and the photons. The discrimination will rather be achieved by time of flight methods which is discussed under the second chapter in this thesis; Experimental results. An other experiment was done in order to investigate whether it is possible to detect any delayed components from the spontaneous fission of Cf. The result showed that delayed components existed. Either they are delayed neutrons from exited fission products, or it is some delay related to the charge collection in the Cf detector. Correlation measurements showed that few events are coincident. Only 50% of the signals from the plastic scintillator are correlated with the Cf source.

  2. NETs and CF Lung Disease: Current Status and Future Prospects

    Directory of Open Access Journals (Sweden)

    Robert D. Gray

    2015-01-01

    Full Text Available Cystic Fibrosis (CF is the most common fatal monogenic disease among Caucasians. While CF affects multiple organ systems, the principle morbidity arises from progressive destruction of lung architecture due to chronic bacterial infection and inflammation. It is characterized by an innate immune defect that results in colonization of the airways with bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa from an early age. Within the airway microenvironment the innate immune cells including epithelial cells, neutrophils, and macrophages have all been implicated in the host defense defect. The neutrophil, however, is the principal effector cell facilitating bacterial killing, but also participates in lung damage. This is evidenced by a disproportionately elevated neutrophil burden in the airways and increased neutrophil products capable of tissue degradation, such as neutrophil elastase. The CF airways also contain an abundance of nuclear material that may be originating from neutrophils. Neutrophil extracellular traps (NETs are the product of a novel neutrophil death process that involves the expulsion of nuclear material embedded with histones, proteases, and antimicrobial proteins and peptides. NETs have been postulated to contribute to the bacterial killing capacity of neutrophils, however they also function as a source of proteases and other neutrophil products that may contribute to lung injury. Targeting nuclear material with inhaled DNase therapy improves lung function and reduces exacerbations in CF and some of these effects may be due to the degradation of NETs. We critically discuss the evidence for an antimicrobial function of NETs and their potential to cause lung damage and inflammation. We propose that CF animal models that recapitulate the human CF phenotype such as the CFTR−/− pig may be useful in further elucidating a role for NETs.

  3. Neutron beam design for low intensity neutron and gamma-ray radioscopy using small neutron sources

    CERN Document Server

    Matsumoto, T

    2003-01-01

    Two small neutron sources of sup 2 sup 5 sup 2 Cf and sup 2 sup 4 sup 1 Am-Be radioisotopes were used for design of neutron beams applicable to low intensity neutron and gamma ray radioscopy (LINGR). In the design, Monte Carlo code (MCNP) was employed to generate neutron and gamma ray beams suited to LINGR. With a view to variable neutron spectrum and neutron intensity, various arrangements were first examined, and neutron-filter, gamma-ray shield and beam collimator were verified. Monte Carlo calculations indicated that with a suitable filter-shield-collimator arrangement, thermal neutron beam of 3,900 ncm sup - sup 2 s sup - sup 1 with neutron/gamma ratio of 7x10 sup 7 , and 25 ncm sup - sup 2 s sup - sup 1 with very large neutron/gamma ratio, respectively, could be produced by using sup 2 sup 5 sup 2 Cf(122 mu g) and a sup 2 sup 4 sup 1 Am-Be(37GBq)radioisotopes at the irradiation port of 35 cm from the neutron sources.

  4. Boron dose enhancement for Cf-252 brachytherapy

    International Nuclear Information System (INIS)

    Full text: Monte Carlo modelling of a Cf-252 source in water and in tissue has shown that there is a significant therapeutic advantage obtained if B-10 is present in the tumour cells. This study analyses the advantage in terms of therapeutic margin, defined as the distance from the border of the treatment volume where boron-loaded tumour cells will receive a therapeutic dose. Calculations were made with MCNP version 4a on a Pentium 60 MHz computer. Large voxel sizes allowed 70 minute runs to achieve statistical uncertainties of 5% or less for 100,000 source neutrons. Later runs with smaller voxels confirmed the accuracy of the initial calculations. Calculations were made for treatment volume radii up to 11 cm and 30 ppm boron-10. The therapeutic margin for radii in the range 3-9 cm is approximately 10% of the tumour radius. This results in a 30% increase in the volume inside which peripheral tumour cells may receive a therapeutic dose. The median therapeutic ratio within the therapeutic margin varied from 1.05 at 3 cm up to 1.25 at 10 cm. Thus there is little benefit for less advanced tumours with thickness less than 3 cm. However, cervical cancer frequently presents in an advanced state in Southeast Asia and in Aboriginal communities in Australia, partially attributable to low Pap smear screening rates. These conclusions support the development and testing of boron compounds in in vitro and in vivo models for cervical cancer

  5. Management of chronic rhinosinusitis in CF.

    Science.gov (United States)

    Mainz, Jochen G; Koitschev, Assen

    2009-06-01

    Routine CF management often does not include upper airway (UAW) assessment although CFTR defects equally affect the sinonasal mucosa. Up to 50% of CF patients have chronic rhinosinusitis (CRS) and/or nasal polyps, and almost 100% reveal UAW abnormalities on CT scan. CRS impairs quality of life. UAW dysfunction in filtering, humidifying, and warming inspired air affects lower airways and the UAW is a potential site of first colonization and a reservoir for opportunistic bacteria. Therefore, UAW pathology substantially affects overall health in CF. Standard treatments are scarce and mostly lack evidence. Nasal douche can remove mucus and crusts. Recently, delivery of dornase alfa using a vibrating aerosol has shown potential as treatment for CF-related CRS. Surgery is indicated when conservative approaches fail but postoperative relapse is frequent. In summary, upper airway involvement in CF is undertreated and requires prospective investigation and an interdisciplinary consensus on diagnosis and therapy. PMID:19460681

  6. Investigation on 252Cf Fission Fragment Tracks in Polycarbonate Detectors

    Directory of Open Access Journals (Sweden)

    A. Bhattacharyya

    1992-10-01

    Full Text Available Registration and development of fission fragments emitted from /sup 252/Cf source have been carried out in three different polycarbonate detectors. The detectors have been characterised in terms of bulk etch rate and its behaviour. Maximum etchable cone lengths have been compared with the theoretically computed values. Identification of the fission fragments in terms of their mass and charge has been done with the help of the computer programme 'FFR'.

  7. Calibration of a Manganese Bath Relative to 252Cf Nu-Bar

    Science.gov (United States)

    Gilliam, David M.; Yue, Andrew T.; Scott Dewey, M.

    2009-08-01

    A large manganese sulfate bath is employed at the National Institute of Standards and Technology (NIST) to calibrate isotopic neutron sources relative to the national standard neutron source NBS-I. In the past few years many low-emission Cf-252 neutron sources have been calibrated for testing of neutron detectors for the U.S. Department of Homeland Security (DHS). The low-emission DHS sources are about a factor of 100 lower in emission rate than NBS-I, so that background fluctuations become more significant in making accurate calibrations. To verify and improve the calibrations relative to NBS-I, a new calibration for sealed Cf-252 neutron sources has been made by measuring the fission rate of a bare Cf-252 deposit and inferring its neutron emission rate from Cf-252 nu-bar, the well-established neutron multiplicity of spontaneous fission in Cf-252. The fission rate of the bare deposit was measured by counting fission fragments in vacuum with a surface barrier detector behind an aperture and spacer, which provided a well-defined solid angle for detection. A thin polyimide film was placed just above the Cf deposit to prevent contamination of the detector by self-sputtering of the Cf material in vacuum. Tests with additional layers of polyimide were performed to observe any perturbation in the detection efficiency due to scattering or absorption of alpha particles or fission fragments in the polyimide film. The increase in the background count rate due to accumulation of Cf on the polyimide film was less than 0.02% of the fission fragment count rate from the sample, at the end of all runs. It is estimated that this increase in background would have been about 150 times higher without the polyimide film. The sealed Cf source NIST-DHSA was compared to the bare source by relative neutron counting in an assembly of polyethylene moderator and He-3 detectors. The calibration via Cf-252 nu-bar gave a result that was 1.7% higher than the previous calibration relative to NBS

  8. Absolute measurements of anti ν (252Cf) using the manganese bath method

    International Nuclear Information System (INIS)

    By the manganese bath method and defined solid angle counting the fission rate anti ν (Cf-252) was measured. The corrections for neutrons losses due to leakage and absorption in the source itself and its surroundings were measured experimentally. The corrections for absorption fast neutrons on S and O was calculated by Monte-Carlo method. The obtained value of anti ν (Cf- 252) is 3.758+-0.015

  9. Scandinavian Nurse Specialist Group/Cystic Fibrosis (SNSG/CF)

    DEFF Research Database (Denmark)

    Bregnballe, Vibeke; Erwander, Inger

    2006-01-01

    Scandinavian CF nurses. A twelve-day CF course equivalent to 5 ECTS has been held once. Twenty-one nurses, physiotherapists and dieticians attended the course and the course will be repeated. SNSG/CF plans to make a common Scandinavian database on nursing interventions in CE SNSG/CF aims to conduct common...

  10. Relative biological efficiency of powerful 252Cf mixed α-neutron radiation

    International Nuclear Information System (INIS)

    Comprehensive radiobiological studies of the relative biological and genetic efficacy (RBE and RGE) of powerful 252Cf radiation (the ANET-B unit) were conducted using research tools of various radiosensitivity (bacteria, Drosophila, Chinese hamster cells, murine thymocytes, human and murine bone marrow stem cells, human peripheral blood lymphocytes, Lewis lung carcinoma cells). It was shown in the tests of reproductive or interphase death and chromosome aberrations that the RBE and the RGE values of a sup(252)Cf new source varied within the same limits from 1.3 to 3.0 whereas in the tests of gene mutations the RGE of the source did not exceed the efficacy of 60Co γ-radiation and in some cases it was much lower. Thus the RBE of the new source in induced lethal and chromosome demages was 2-4 times lower than the efficacy of a low-activity sup(252)Cf source used now in radiotherapy

  11. Spectrometry and dosimetry of isotopic sources of neutrons by means of artificial neural networks

    International Nuclear Information System (INIS)

    The artificial neural networks technology has been applied to reconstruct the neutrons spectra of two isotopic sources: 252Cf, and 241Am-Be. Also, this technology has been applied to obtain the effective dose, E, and the personal dose equivalents, Hp(10) and environmental, H *(10). To obtain the spectra and the doses only were used the count rates produced in a Bonner Spheres spectrometer with a scintillator of 6LiI(Eu) of 0.4 φ x 0.4 cm2. The equivalent environmental dose and the spectra of the sources were also obtained by means of the reconstruction code BUNKIUT. When comparing the results obtained by means of both procedures it was found that they are consistent. (Author)

  12. Estimated photochemical ozone creation potentials (POCPs) of CF3CF = CH2 (HFO-1234yf) and related hydrofluoroolefins (HFOs)

    DEFF Research Database (Denmark)

    Wallington, T. J.; Andersen, Mads Peter Sulbæk; Nielsen, Ole John

    2010-01-01

    The photochemical ozone creation potentials (POCPs) for CF3CF=CH2 and other commercially significant hydrofluoroolefins have been estimated for the first time. CF3CF=CH2 (HFO-1234yf) has a POCP of 7.0 which is less than that for ethane (12.3) and greater than for methane (0.6). Methane and ethane...

  13. Delivery of genes into the CF airway.

    Science.gov (United States)

    Gill, Deborah R; Hyde, Stephen C

    2014-10-01

    Gene therapy was suggested as a potential treatment for cystic fibrosis (CF), even before the identification of the CFTR gene. Initial enthusiasm has been tempered as it became apparent that reintroduction of the CFTR gene into the cells of the lung is more difficult than anticipated. Here, we review the major gene delivery vectors evaluated clinically, and suggest that advances in either plasmid DNA design and/or hybrid lentivirus biology may finally facilitate lung gene transfer with efficiencies sufficient for CF gene therapy to offer clinical benefit. PMID:25015239

  14. Binary and ternary spontaneous fission of 252 Cf

    International Nuclear Information System (INIS)

    The high selectivity and sensitivity offered by large detector arrays such as GAMMASPHERE and EUROGAM enable one to identify several gamma-rays related to the binary and ternary spontaneous fission. The yields for Mo-Ba binary spontaneous fission were extracted again from the data with better statistics. A new experiment with the 252 Cf source has been done by using a Delta telescope and GAMMASPHERE arrays at Argonne National Laboratory. From these data and our older data, new relative alpha ternary spontaneous fission yields were extracted. These results and the emission of 10 Be in spontaneous fission and the existence of long lived nuclear molecule also will be discussed. (author)

  15. Atmospheric measurements of CF4 and other fluorocarbons containing the CF3 grouping

    International Nuclear Information System (INIS)

    Careful measurements by GC/MS techniques on atmospheric carbon tetrafluoride confirm that its concentration in 1979 was constant at about 69.9 pptv (standard deviation is 7.2 pptv). It is almost certainly produced entirely by emissions from the aluminum industry. Other compounds in the atmosphere containing the CF3 group have been identified by GC/MS as C2F6, CF3CL, CF3Br,and C2F5CL. The concentrations of the first pair are about 4 pptv, and the latter two are about 0.7 pptv and 4 pptv, respectively. The C2F6 is produced simultaneously with CF4 in the manufacture of aluminum. CF3Cl, CF3Br, and C2F5Cl are probably produced by the chemical industry. The environmental importance of these compounds is discussed in the context of two papers on CF4 recently published by Cicerone (1979) and by Wang et al

  16. Duodenal Intracellular Bicarbonate and the 'CF Paradox'

    Directory of Open Access Journals (Sweden)

    Kaunitz JD

    2001-07-01

    Full Text Available HCO(3(- secretion, which is believed to neutralize acid within the mucus gel, is the most studied duodenal defense mechanism. In general, HCO(3(- secretion rate and mucosal injury susceptibility correlate closely. Recent studies suggest that luminal acid can lower intracellular pH (pH(i of duodenal epithelial cells and that HCO(3(- secretion is unchanged during acid stress. Furthermore, peptic ulcers are rare in cystic fibrosis (CF, although, with impaired HCO(3(- secretion, increased ulcer prevalence is predicted, giving rise to the 'CF Paradox'. We thus tested the hypothesis that duodenal epithelial cell protection occurs as the result of pH(i regulation rather than by neutralization of acid by HCO(3(- in the pre-epithelial mucus. Cellular acidification during luminal acid perfusion, and unchanged HCO(3(- secretion during acid stress are inconsistent with pre-epithelial acid neutralization by secreted HCO(3(-. Furthermore, inhibition of HCO(3(- secretion by 5-nitro-2-(3-phenylpropylamino benzoic acid (NPPB despite preservation of pH(i and protection from acid-induced injury further question the pre-epithelial acid neutralization hypothesis. This decoupling of HCO(3(- secretion and injury susceptibility by NPPB (and possibly by CF further suggest that cellular buffering, rather than HCO(3(- exit into the mucus, is of primary importance for duodenal mucosal protection, and may account for the lack of peptic ulceration in CF patients.

  17. Observation of Light Shape Isomers in the Multi-Body Decay of 252Cf (sf)

    Science.gov (United States)

    Pyatkov, Yu. V.; Kamanin, D. V.; Alexandrov, A. A.; Alexandrova, I. A.; Kondratyev, N. A.; Kuznetsova, E. A.; Strekalovsky, A. O.; Strekalovsky, O. V.; Zhuchko, V. E.; Mkaza, N.; Malaza, V.

    2015-11-01

    We observe an essential mass deficit in the total mass of the fission fragments detected in coincidence with Ti ions knocked out from the foil placed near a 252Cf source. This could be expected if the scattered fragment looks like a di-nuclear system breaking up due to inelastic scattering on the Ti nucleus. The mean flight time between the Cf source and the foil does not exceed 0.1 ns. This can be regarded as a lower limit for the life-time of the di-nuclear system (shape-isomer).

  18. M-C simulation of 252Cf spontaneous fission n/γ TOF and TCC spectra

    International Nuclear Information System (INIS)

    Time correlation coincidence (TCC) is an effective method to measure characteristics of fission materials. In this paper, MCNP code is used to simulate n/γ time-of-flight spectra (TOF) of a 252Cf spontaneous fission source detected by a BC-501A liquid scintillator. The results are in good agreement with the measured spectra. Therefore, n/γ TCC spectra of the 252Cf source are simulated. The results indicate that the n/γ TCC spectra are composed of the n-n, γ-γ, n-γ and γ-n coincidence. (authors)

  19. Neutron spectra and dosimetric features of isotopic neutron sources: a review

    International Nuclear Information System (INIS)

    A convenient way to produce neutrons is the isotopic neutron source, where the production is through (α, n), (γ, n), and spontaneous fission reactions. Isotopic neutron sources are small, easy to handle, and have a relative low cost. On the other hand the neutron yield is small and mostly of them produces neutrons with a wide energy distribution. In this work, a review is carried out about the the main features of 24NaBe, 24NaD2O, 116InBe, 140LaBe, 238PuLi, 239PuBe, 241AmB, 241AmBe, 241AmF, 241AmLi, 242CmBe, 210PoBe, 226RaBe, 252Cf and 252Cf/D2O isotopic neutron source. Also, using Monte Carlo methods, the neutron spectra in 31 energy groups, the neutron mean energy; the Ambient dose equivalent, the Personal dose equivalent and the Effective dose were calculated for these isotopic neutron sources. (Author)

  20. Neutron spectra and dosimetric features of isotopic neutron sources: a review

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico); Martinez O, S. A., E-mail: fermineutron@yahoo.com [Universidad Pedagogica y Tecnologica de Colombia, Grupo de Fisica Nuclear Aplicada y Simulacion, Av. Central del Norte 39-115, 150003 Tunja, Boyaca (Colombia)

    2015-10-15

    A convenient way to produce neutrons is the isotopic neutron source, where the production is through (α, n), (γ, n), and spontaneous fission reactions. Isotopic neutron sources are small, easy to handle, and have a relative low cost. On the other hand the neutron yield is small and mostly of them produces neutrons with a wide energy distribution. In this work, a review is carried out about the the main features of {sup 24}NaBe, {sup 24}NaD{sub 2}O, {sup 116}InBe, {sup 140}LaBe, {sup 238}PuLi, {sup 239}PuBe, {sup 241}AmB, {sup 241}AmBe, {sup 241}AmF, {sup 241}AmLi, {sup 242}CmBe, {sup 210}PoBe, {sup 226}RaBe, {sup 252}Cf and {sup 252}Cf/D{sub 2}O isotopic neutron source. Also, using Monte Carlo methods, the neutron spectra in 31 energy groups, the neutron mean energy; the Ambient dose equivalent, the Personal dose equivalent and the Effective dose were calculated for these isotopic neutron sources. (Author)

  1. A 252Cf based nondestructive assay system for fissile material

    International Nuclear Information System (INIS)

    A modulated 252Cf source assay system 'Shuffler' based on fast-or-thermal-neutron interrogation combined with delayed-neutron counting has been developed for the assay of fissile material. The 252Cf neutron source is repetitively transferred from the interrogation position to a shielded position while the delayed neutrons are counted in a high efficiency 3He neutron well-counter. For samples containing plutonium, this well-counter is also used in the passive coincidence mode to assay the effective 240Pu content. The design of an optimized neutron tailoring assembly for fast-neutron interrogation using a Monte Carlo Neutron Computer Code is described. The Shuffler system has been applied to the assay of fuel pellets, inventory samples, irradiated fuel and plutonium mixed-oxide fuel. The system can assay samples with fissile contents from a few milligrams up to several kilograms using thermal-neutron interrogation for the low mass samples and fast-neutron interrogation for the high mass samples. Samples containing 235U-238U, or 233U-Th, or UO2-PuO2 fuel mixtures have been assayed with the Shuffler system. (Auth.)

  2. Atmospheric chemistry of 4 : 2 fluorotelomer alcohol (CF3(CF2)(3)CH2CH2OH): Products and mechanism of Cl atom initiated oxidation

    DEFF Research Database (Denmark)

    Hurley, MD; Ball, JC; Wallington, TJ;

    2004-01-01

    Smog chamber/FTIR techniques were used to study the products and mechanism of the Cl atom initiated oxidation of 4:2 fluorotelomer alcohol (CF3(CF2)(3)CH2CH2OH) in 700 Torr of N-2/O-2 diluent at 296 K. CF3(CF2)(3)CH2CHO is the sole primary oxidation product. CF3(CF2)(3)CHO, CF3(CF2)(3)CH2COOH, and...... CF3(CF2)(3)CH2C(O)OOH are secondary oxidation products. Further irradiation results in the formation of CF3(CF2)(3)COOH, COF2, and CF3OH. CF3(CF2)(3)CHO, CF3(CF2)(3)CH2COOH, and CF3(CF2)(3)CH2C(O)OOH are formed from CF3(CF2)(3)CH2CHO oxidation in yields of 46 27 and less than or equal to 27...... respectively. Using relative rate techniques, a value of k(Cl + CF3(CF2)(3)CH2CHO) = (1.84 +/- 0.30) x 10(-11) cm(3) molecule(-1) s(-1) was determined. The yield of the perfluorinated acid, CF3(CF2)(3)COOH, from the 4:2 fluorotelomer alcohol increased with the diluent gas oxygen concentration. For the...

  3. GEM photomultiplier operation in CF4

    International Nuclear Information System (INIS)

    The properties of a 3-GEM (Gas Electron Multiplier) element photomultiplier, with a semitransparent CsI photocathode and CF4 gas filling, are presented. Compared to other gas mixtures, such as CH4, Ar/CH4, Ar/N2 and He/Ar/N2, CF4 has superior performance: the highest gain, approaching 107, the fastest, 8 ns wide signal and the lowest photoelectron backscattering; the latter allows to reach photocathode quantum efficiency values approaching that in vacuum. The time resolution of the multi-GEM photomultiplier for single photoelectrons was measured to be 2 ns. These properties are of high relevance for applications in Cherenkov detectors and in tracking devices

  4. Stochastic tracking of infection in a CF lung.

    Directory of Open Access Journals (Sweden)

    Sara Zarei

    Full Text Available Magnetic Resonance Imaging (MRI and Computed Tomography (CT scan are the two ubiquitous imaging sources that physicians use to diagnose patients with Cystic Fibrosis (CF or any other Chronic Obstructive Pulmonary Disease (COPD. Unfortunately the cost constraints limit the frequent usage of these medical imaging procedures. In addition, even though both CT scan and MRI provide mesoscopic details of a lung, in order to obtain microscopic information a very high resolution is required. Neither MRI nor CT scans provide micro level information about the location of infection in a binary tree structure the binary tree structure of the human lung. In this paper we present an algorithm that enhances the current imaging results by providing estimated micro level information concerning the location of the infection. The estimate is based on a calculation of the distribution of possible mucus blockages consistent with available information using an offline Metropolis-Hastings algorithm in combination with a real-time interpolation scheme. When supplemented with growth rates for the pockets of mucus, the algorithm can also be used to estimate how lung functionality as manifested in spirometric tests will change in patients with CF or COPD.

  5. Brachytherapy of carcinoma of vulva with 252Cf

    International Nuclear Information System (INIS)

    Thirty patients with carcinoma of vulva were treated with interstitial neutron radiotherapy with 252Cf. Age of patients was from 32 to 83 years. Stage I was in I patient, stage II - in 12, stage III was in 10 patients. The diagnosis of vulvar cancer was made for the first time in 11 cases, 19 patients had recurrences after the initial treatment. Most of these patients also received external irradiation for cancer of vulva and bilateral inguinal sites with a single fraction dose of 2 Gy to a total dose 30-50 Gy. Enlarged inguinal lymph nodes were irradiated additionally to 60 Gy with reduced field of irradiation. When radiotherapy was used repeatedly interstitial brachytherapy comprised the major part of irradiation dose or the therapy was used alone delivering 35-55 iGy. We used 252Cf sources with increased activity at the ends 20-30 mm long. A number of inserted sources varied from 2 to 10, irradiation dose rate from 20.3 to 236.7 cGy/h, time of irradiation from 10.2 to 12. hours, RBE from 4.6 to 6.33. Special template device made it possible to implant sources in strictly pre-set geometry. Analysis of survival of patients showed that 2 years survival was 66%, 3 years - 60%, and 5 years survival was 49%. In two cases necrotic epithelitis developed with following radiation ulcer which were cured in 3-4 months. Clinical data showed great effectiveness of interstitial neutron therapy having in mind that 19 patients were treated for recurrences of vulvar cancer after previuos treatment

  6. Radiation Source Replacement Workshop

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, Jeffrey W.; Moran, Traci L.; Bond, Leonard J.

    2010-12-01

    This report summarizes a Radiation Source Replacement Workshop in Houston Texas on October 27-28, 2010, which provided a forum for industry and researchers to exchange information and to discuss the issues relating to replacement of AmBe, and potentially other isotope sources used in well logging.

  7. Study of fusion reactions forming Cf nuclei

    Directory of Open Access Journals (Sweden)

    Khuyagbaatar J.

    2013-12-01

    Full Text Available The formation of a compound nucleus in different projectile and target combinations is a powerful method for investigating the fusion process. Recently, the dominance of quasi-fission over fusion-fission has been inferred for 34S+208Pb in comparison to 36S+206Pb; both reactions lead to the compound nucleus 242Cf*.The mass and angle distributions of the fission fragments from these reactions were studied in order to further investigate the presence of quasi-fission.

  8. Spectrometry and dosimetry of isotopic sources of neutrons by means of artificial neural networks; Espectrometria y dosimetria de fuentes isotopicas de neutrones mediante redes neuronales artificiales

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R.; Ortiz R, J. M.; Hernandez D, V. M; Martinez B, M. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Gallego, E.; Lorente, A. [Universidad Politecnica de Madrid, Departamento de Ingenieria Nuclear, C/Jose Gutierrez Abascal No. 2, 28006 Madrid (Spain); Barquero, R., E-mail: fermineutron@yahoo.co [Hospital del Rio Hortega, C/Dulzaina No. 2, 47012 Valladolid (Spain)

    2010-09-15

    The artificial neural networks technology has been applied to reconstruct the neutrons spectra of two isotopic sources: {sup 252}Cf, and {sup 241}Am-Be. Also, this technology has been applied to obtain the effective dose, E, and the personal dose equivalents, Hp(10) and environmental, H *(10). To obtain the spectra and the doses only were used the count rates produced in a Bonner Spheres spectrometer with a scintillator of {sup 6}LiI(Eu) of 0.4 {phi} x 0.4 cm{sup 2}. The equivalent environmental dose and the spectra of the sources were also obtained by means of the reconstruction code BUNKIUT. When comparing the results obtained by means of both procedures it was found that they are consistent. (Author)

  9. Electron Cyclotron Resonance Based Chemically Assisted Plasma Etching Of Silicon in CF4/Ar Plasma

    Science.gov (United States)

    Bhardwaj, R. K.; Angra, S. K.; Bajpai, R. P.; Lal, Madan; Bharadwaj, Lalit M.

    2005-09-01

    Etching of silicon in Chemical Assisted Plasma Etching mode with CF4 gas being sprayed on the surface of wafer in process chamber and Ar fed to ECR cavity in Electron Cyclotron Resonance (ECR) source was carried out. The plasma source was 2.45 GHz microwave source superimposed with mirror type magnetic field configuration to have resonance. Effect of CF4/Ar ratio and substrate bias on etching rate of silicon and anisotropy of etched profile has been investigated. The variation of etch rate and anisotropy has been correlated to the availability of fluorine atoms and other radicals available for etching. Optimum parameters required for etching of silicon in chemical assisted plasma etching with self-assembled ECR plasma source has been established.

  10. Electron Cyclotron Resonance Based Chemically Assisted Plasma Etching Of Silicon in CF4/Ar Plasma

    International Nuclear Information System (INIS)

    Etching of silicon in Chemical Assisted Plasma Etching mode with CF4 gas being sprayed on the surface of wafer in process chamber and Ar fed to ECR cavity in Electron Cyclotron Resonance (ECR) source was carried out. The plasma source was 2.45 GHz microwave source superimposed with mirror type magnetic field configuration to have resonance. Effect of CF4/Ar ratio and substrate bias on etching rate of silicon and anisotropy of etched profile has been investigated. The variation of etch rate and anisotropy has been correlated to the availability of fluorine atoms and other radicals available for etching. Optimum parameters required for etching of silicon in chemical assisted plasma etching with self-assembled ECR plasma source has been established

  11. Burnout and gate rupture of power MOS transistors with fission fragments of 252Cf

    International Nuclear Information System (INIS)

    A study to determine the single event burnout (SEB) and single event gate rupture (SEGR) sensitivities of power MOSFET devices is carried out by exposure to fission fragments from 252Cf source. The test method, test results, a description of observed burnout current waveforms and a discussion of a possible failure mechanism are presented. The test results include the observed dependence upon applied drain or gate to source bias and effect of external capacitors and limited resistors

  12. Langmuir probe and mass spectrometric measurements in inductively coupled CF4 plasmas

    International Nuclear Information System (INIS)

    Electron and ion energy distribution functions and other plasma parameters such as plasma potential (Vp), electron temperature (Te) and electron and ion number densities (ne and ni) in low-pressure CF4 plasmas have been measured. The experiments were conducted in a GEC cell using an inductively coupled plasma device powered by a 13.56 MHz radiofrequency (rf) power source. The measurements were made at 300 W of input rf power at 10, 30 and 50 mTorr gas pressures. Langmuir probe measurements suggest that ne, ni and Vp remain constant over 60% of the central electrode area, beyond which they decrease. Within the limits of experimental error (±0.25 eV), Te remains nearly constant over the electrode area and peaks towards the electrode edge before falling rapidly. Te and Vp increase with a decrease in pressure. ne and ni are not affected as significantly as Te or Vp by variation in the gas pressure. The electron energy distribution function measurements indicate a highly non-Maxwellian plasma. CF3+ is the most dominant ion product of the plasma, followed by CF2+ and CF+. Significant amounts of etch products, SiFx/COFx(x = 0-3), of the quartz window were also detected. The concentrations of CF2+ and CF+ are much larger than that is possible from direct electron impact ionization of the parent gas. The cross-section data suggest that the direct electron impact ionization of fragment neutrals and negative ion production by electron attachment may be responsible for increase of the minor ions

  13. Embeddings into Thompson's group V and coCF groups

    OpenAIRE

    Bleak, Collin; Matucci, Francesco; Neunhöffer, Max

    2016-01-01

    Lehnert and Schweitzer show in [21] that R. Thompson's group V is a co-context-free (coCF ) group, thus implying that all of its finitely generated subgroups are also coCF groups. Also, Lehnert shows in his thesis that V embeds inside the coCF group QAut(T2;c), which is a group of particular bijections on the vertices of an infinite binary 2-edge-colored tree, and he conjectures that QAut(T2;c) is a universal coCF group. We show that QAut(T2;c) embeds into V , and thus obtain a new form for L...

  14. Atmospheric chemistry of (CF3)2CFOCH3

    DEFF Research Database (Denmark)

    Andersen, Lene Løffler; Østerstrøm, Freja From; Nielsen, Ole John;

    2014-01-01

    FTIR smog chamber techniques were used to measure k(Cl + (CF 3)2CFOCH3) = (1.80 ± 0.42) × 10-13, k(Cl + (CF3)2CFOCHO) = (1.47 ± 0.56) × 10-14, and k(OH + (CF3) 2CFOCH3) = (1.55 ± 0.24) × 10-14 cm3 molecule-1 s-1. The chlorine-atom initiated oxidation of (CF3)2CFOCH3 in air in the absence of NOX r...

  15. Upper limits for the rate constants of the reactions of CF3O2 and CF3O radicals with ozone at 295 K

    DEFF Research Database (Denmark)

    Nielsen, O.J.; Sehested, J.

    1993-01-01

    Using the pulse radiolysis UV absorption technique and subsequent simulations of experimental absorption transients at 254 and 276 nm, upper limits of the rate constants for the reactions of CF3O2 and CF3O radicals with ozone were determined at 295 K, CF3O2+O3-->CF3O+2O2 (4), CF3O+O3-->CF3O2+O2 (......). The upper limits were derived as k4 ozone depletion by hydrofluorocarbons.......Using the pulse radiolysis UV absorption technique and subsequent simulations of experimental absorption transients at 254 and 276 nm, upper limits of the rate constants for the reactions of CF3O2 and CF3O radicals with ozone were determined at 295 K, CF3O2+O3-->CF3O+2O2 (4), CF3O+O3-->CF3O2+O2 (5...

  16. Metal free and selective activation of one C-F bond in a bound CF3 group.

    OpenAIRE

    Azhakar, Ramachandran; Roesky, Herbert W.; Wolf, Hilke; Stalke, Dietmar

    2013-01-01

    The first metal free selective C-F bond activation of a CF(3) group was observed with N-heterocyclic silylenes [PhC(NtBu)(2)SiCl] (1) and [CH{(C=CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}Si] (2) with PhN=C(CF(3))(2). The reaction proceeds in a 1 : 1 molar ratio to yield the mono C-F bond activated products 3 and 4 with each containing a CF(2) group. Both the reactions proceed through an unprecedented selective activation of one of the C-F bonds rather than forming the [1+2] cycloaddition product co...

  17. 252Cf-based borehole logging system for in-situ assaying of uranium ore

    International Nuclear Information System (INIS)

    A 252Cf based borehole logging system for in-situ assaying of uranium ore has been designed and constructed, and preliminary tests of system operation have been performed. The system employs a delayed neutron activation analysis (DNAA) technique for which the downhole feasibility was demonstrated by Kerr--McGee. DNAA measures uranium directly, thereby circumventing the disequilibrium problems which are inherent to natural gamma ray logging. An improved DNAA technique has been implemented which utilizes a smaller 252Cf source and is more sensitive than the Kerr--McGee system. In particular, the size of the 252Cf source has been reduced by more than a factor of 10 with respect to the source employed by Kerr--McGee. Shielding for the 252Cf source has been designed for ease of operation while meeting occupational radiological safety requirements. The present system is vehicle mounted and includes the downhole sonde, logging winch with 1,000 meters of 4HO cable, data handling electronics, data recording and display equipment, and source shielding. The design of the system includes the following features: logging speeds from stationary to 8 meters/min with the capacity for determining 0.01% U3O8 concentration at 1.5 meters/min; uranium concentration readout independent of source intensity; auxiliary neutron measurement for accurate correlation of DNAA signal to actual U3O8 present; natural gamma ray detector for gauging disequilibrium; and short normal resistivity for lithology. The present system is a fully operational prototype. An extensive field calibration and evaluation program will begin shortly to uncover design problems and to allow simplification of the system for production logging. Commercially available units will reflect the operational experience gained from the testing program

  18. Estimated photochemical ozone creation potentials (POCPs) of CF 3CF dbnd CH 2 (HFO-1234yf) and related hydrofluoroolefins (HFOs)

    Science.gov (United States)

    Wallington, T. J.; Sulbaek Andersen, M. P.; Nielsen, O. J.

    2010-04-01

    The photochemical ozone creation potentials (POCPs) for CF 3CF dbnd CH 2 and other commercially significant hydrofluoroolefins have been estimated for the first time. CF 3CF dbnd CH 2 (HFO-1234yf) has a POCP of 7.0 which is less than that for ethane (12.3) and greater than for methane (0.6). Methane and ethane have sufficiently low POCPs that they are usually considered unreactive with respect to ozone formation in urban areas and accordingly are exempt from volatile organic compound (VOC) emission regulations. Estimated POCPs for other hydrofluoroolefins are: CH 2dbnd CF 2, 18.0; CF 2dbnd CF 2, 12.5; CH 2dbnd CHCF 3, 10.7; CF 2dbnd CFCF 3, 5.4; Z-CHF dbnd CFCF 3, 5.6; E-CHF dbnd CFCF 3, 7.3; CH 2dbnd CHCF 2CF 3, 6.6; and t-CHF dbnd CHCF 3, 6.4.

  19. Time-resolved tunable diode laser detection of products of CF 2HCl IRMPD: A linestrength measurement for CF 2

    Science.gov (United States)

    Orlando, J. J.; Reid, J.; Smith, D. R.

    1987-11-01

    Tunable diode laser transient detection of CF 2 C 2F 4, and HCl following infrared multiphoton dissociation (IRMPD) of CF 2HCl has been achieved. Quantification of the HCl and C 2F 4 leads to the calculation of an infrared absorption linestrength and the ν 1 bandstrength for CF 2 (X˜ 1A 1). In addition, the rate coefficient for recombination of CF 2 was found to be (1.4± 0.4) × 10 10 cm 3 mol -1 s -1.

  20. On the use of a ({sup 252}Cf-{sup 3}He) assembly for landmine detection by the neutron back-scattering method

    Energy Technology Data Exchange (ETDEWEB)

    Elsheikh, N., E-mail: nassreldeen.elsheikh@yahoo.com [College of Applied and Industrial Science, Department of Physics, University of Juba, Khartoum, P.O. Box 12327/1 (Sudan); Viesti, G. [Dipartimento di Fisica ed Astronomia dell' Universita di Padova, Via Marzolo 8, I-35131 Padova (Italy); ElAgib, I. [College of Science, King Saud University, P.O. Box 2455 (Saudi Arabia); Habbani, F. [Faculty of Science, Physics Department, University of Khartoum, Khartoum, P.O. Box 321 (Sudan)

    2012-04-15

    Experiments were carried out to optimize the performance of the neutron back-scattering (NBS) technique in landmine detection using an assembly consisting of three different layers placed above a {sup 252}Cf neuron source, producing about 10{sup 4} s{sup -1}, in conjunction with a {sup 3}He detector. The assembly was optimized experimentally. The selected assembly configuration was then examined against different {sup 252}Cf stand-off distances and mine burial depths using dummy landmines. Furthermore, Monte Carlo simulations were performed to study the effect of the shield when a {sup 252}Cf source in the range 10{sup 4}-10{sup 7} s{sup -1} was employed, and to optimize the geometry for future prototypes. - Highlights: Black-Right-Pointing-Pointer A suitable shielded ({sup 252}Cf-{sup 3}He) assembly for landmine detection was developed. Black-Right-Pointing-Pointer Experimental tests and MCNP simulations were performed for a {sup 252}Cf of (10{sup 4}-10{sup 7})s{sup -1}. Black-Right-Pointing-Pointer Experimental and MCNP results for {sup 252}Cf of 10{sup 4}s{sup -1} supports the use of the shield. Black-Right-Pointing-Pointer MCNP Results recommends {sup 252}Cf of 10{sup 6}s{sup -1} for hand-held detection system. Black-Right-Pointing-Pointer MCNP Results recommends {sup 252}Cf of 10{sup 7}s{sup -1} for a robotic detection system.

  1. 252Cf中子照射中国参考人模体24Na比活度的实验研究%Experimental research on specific activity of 24Na using Chinese reference man phantom irradiated by 252Cf neutrons source

    Institute of Scientific and Technical Information of China (English)

    王月兴; 杨翊方; 鲁永杰; 张建国; 邢宏传

    2011-01-01

    Objective To investigate the specific activity of 24Na per unit neutron fluence,AB/Φ,in blood produced for Chinese reference man irratiaded by 252Cf neutron source,and to analyze the effects of scattering neutrons from ground,wall,and ceiling in irradiation site on it.MethodsA 252Cf neutron source of 3 × 108 n/s and the anthropomorphic phantom were used for experiments.The phantom was made from 4 mm thick of outer covering by perspex and the liquid tissue-equivalent substitute in it.The data of phantom dimensions fit into Chinese reference man.The weight ratios of H,N,O and C in substitute equal from source to long axis of phantom were 1.1,2.1,3.1 and 4.1 m,respectively.Both the neutron source and the position of xiphisternum of the phantom were 1.6 m above the floor.ResultsThe average specific activity of 24Na per unit neutron fluence was related to the irradiation-distances,d,and its The AB/ΦM corresponds to that of phantom irradiated by plane-parallel beams,and the value is about more 3% than that by BOMAB phantom reported in literature.It has shown that floor-( wall-)scattered neutrons in irradiation site have significant contribution to the specific activity of 24Na ,but they contributed relatively little to the induced neutron doses.Consequently,using the specific activity of 24 Na for assessing accidental neutron doses received by an individual,the contribution of scattered neutrons in accident site will lead dose to be overestimated,and need to be correct.%目的 研究裂变中子谱照射中国参考人单位中子注量在血液中产生的24Na比活度AB/φ,并分析实验场所地板、墙壁和天花板等的散射中子对测量结果的影响.方法 利用强度约3×108中子/s的252Cf中子源对中国参考人模体进行照射.模体躯干尺寸按中国参考人制作,外壳由4 mm有机玻璃制成,内有人体组织当量液,主要元素的重量比为H∶N∶O∶C=10.6∶2.5∶63.2∶23.7,密度1.007g/cm3(20℃).中子源到模体长轴

  2. Atmospheric chemistry of CF3CF=CH2: Kinetics and mechanisms of gas-phase reactions with Cl atoms, OH radicals, and O-3

    DEFF Research Database (Denmark)

    Nielsen, O. J.; Javadi, M. S.; Andersen, Mads Peter Sulbæk;

    2007-01-01

    Long path length FTIR-smog chamber techniques were used to determine k(Cl + CF3CF=CH2) = (7.03 +/- 0.59) x 10(-11) k(OH + CF3CF=CH2) = (1.05 +/- 0.17) x 10(-12), and k(O-3 + CF3CF=CH2) = (2.77 +/- 0.21) x 10(-21) cm(3) molecule' s(-1) in 700 Torr of N-2, N-2/O-2, or air diluent at 296 K. CF3CF=CH...

  3. Attributes and templates from active measurements with 252Cf

    International Nuclear Information System (INIS)

    Active neutron interrogation is useful for the detection of shielded HEU and could also be used for Pu. In an active technique, fissile material is stimulated by an external neutron source to produce fission with the emanation of neutrons and gamma rays. The time distribution of particles leaving the fissile material is measured with respect to the source emission in a variety of ways. A variety of accelerator and radioactive sources can be used. Active interrogation of nuclear weapons/components can be used in two ways: template matching or attribute estimation. Template matching compares radiation signatures with known reference signatures and for treaty applications has the problem of authentication of the reference signatures along with storage and retrieval of templates. Attribute estimation determines, for example, the fissile mass from various features of the radiation signatures and does not require storage of radiation signatures but does require calibration, which can be repeated as necessary. A nuclear materials identification system (NMIS) has been in use at the Oak Ridge Y-12 Plant for verification of weapons components being received and in storage by template matching and has been used with calibrations for attribute (fissile mass) estimation for HEU metal. NMIS employs a 252Cf source of low intensity (6 n/sec) such that the dose at 1 m is approximately twice that on a commercial airline at altitude. The use of such a source presents no significant safety concerns either for personnel or nuclear explosive safety, and has been approved for use at the Pantex Plant on fully assembled weapons systems

  4. Neutron sources for in-situ planetary science applications

    Energy Technology Data Exchange (ETDEWEB)

    Skidmore, M.S. [Space Research Centre, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom)], E-mail: mss16@star.le.ac.uk; Ambrosi, R.M.; O' Brien, R.C. [Space Research Centre, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom)

    2009-09-21

    There are a number of future European Space Agency (ESA) and NASA planetary science missions that are in the planning or initial study phases, where the scientific objectives include determining the surface composition, measuring planetary surface heat flow and constraining planetary chronology. University of Leicester is developing instrumentation for geophysical applications that include {gamma}-ray spectroscopy, {gamma}-ray densitometry and radiometric dating. This paper describes the modelling of a geophysical package, with the Monte Carlo code MCNPX, in order to determine the impact that a neutron source would have on in-situ composition measurements, radiometric dating and, in particular, trace element detection. The suitability of o 2.54x2.54 cm LaBr{sub 3}(Ce) detectors in the geophysical package for in-situ missions was examined. {sup 252}Cf, Am-Be and Pu-Be neutron sources were compared in a trade-off study to determine mission suitability, potential for thermal and electric power production, mass and shielding requirements. This study is linked to a parallel examination of the suitability of radioisotope thermal generators for in-situ planetary science applications. The aim of the modelling was to optimise the source type and detector geometry in order to measure the elemental peaks of interest with a precision of 10% or better based on the Poisson statistics of the detected counts above background.

  5. True ternary fission of 252Cf

    International Nuclear Information System (INIS)

    Splitting of heavy radioactive nucleus into three fragments is known as ternary fission. If the size of the fragments are almost equal it is referred to as true ternary fission. Recently, Yu. V. Pyatkov et al observed/reported the experimental observation of true ternary fission in 252Cf. In this work, the possibilities of different true ternary fission modes of 252Cf through potential energy surface (PES) calculations based on three cluster model (TCM) are discussed. In TCM a condition on the mass numbers of the fission fragments is implied as A1 ≥ A2 ≥ A3 in order to avoid repetition of combinations. Due to this condition, the values of Z3 vary from 0 to 36 and Z2 vary from 16 to 51. Of the different pairs having similar (Z2, Z3) with different potential energy, a pair possessing minimum potential energy is chosen. Thus identified favourable combinations are plotted. For the PES calculations the arrangement of the fragments is considered in the order of A1+A2+A3. i.e. the heavy and the lightest fragments are kept at the ends. It is seen that the deepest minimum in the PES occurs for Z3=2 labelled as (Z2; 2) indicating He accompanied breakup as the most favourable one. Of which, the breakup with Z2 around 46 to 48 is the least (shown by dashed (Z1 = 50) and dotted (Z1 = 52) lines indicating a constant Z1 value). The other notable minima in the PES are labelled and they correspond to the (Z2, Z3) pairs viz., (20, 20), (28, 20), (28, 28) and (32, 32). Of these four minima, the first three are associated with the magic numbers 20 and 28. For Z3=20, there are two minimums at (20,20) and (28,20) among them (28,20) is the lowest minimum through which the minimum-path passes, and it is the ternary decay observed by Yu. V. Pyatkov et al. The fourth minima is the most interesting due to the fact that it corresponds to true ternary fission mode with Z2=32, Z3=32 and Z1=34. The minimum potential energy path also goes through this true ternary mode. The PES calculation

  6. Shielding of radiation fields generated by 252Cf in a concrete maze. Part 1: Experiment

    International Nuclear Information System (INIS)

    A concrete room with a single-legged maze was constructed in order to simulate a medical accelerator room. Gamma and neutron measurements were performed along the maze with (a) a 252Cf source and (b) a tungsten-moderated 252Cf source placed inside the room. The measurements were repeated after placing an inner borated polyethylene door of varying thickness (2.54--10.16 cm) at 2 different locations. Measurements were also performed after lining the inside of the maze with different neutron moderating materials. The following results are reported: (1) the variation and contributions of individual components of the radiation fields as a function of distance along the maze, (2) the attenuation of neutron dose equivalent and reduction of capture gamma rays as a function of borated polyethylene (BPE) inner door thickness and location of the inner door; and (3) the effect of lining the maze corner with different neutron moderating materials

  7. Structure of spontaneous fission spectrum of 252Cf and its impact on neutron albedo experiments' simulation

    International Nuclear Information System (INIS)

    Aimed at the problem of the energy spectrum of spontaneous fission source, which was used in neutron albedo experiments, we selected two sets of 252Cf fission spectra, which were fitted by formulae and were universally accepted. And they were applied in neutron albedo experiments independently. Neutron fluence and fission rate on each detecting point were compared and analyzed. The results show that Watt spectrum agrees the experiment data better than that of Maxwell spectrum. (authors)

  8. Neutron radiography research using 252Cf at General Dynamics' Convair Aerospace Division

    International Nuclear Information System (INIS)

    Neutron radiography research using 10 milligrams of 252Cf consisting of 4 sources in a water-moderated tank facility is described. Conventional direct-exposure techniques were employed with thermal neutrons from a 6-in. dia beam port. Typical examples with components representative of aerospace products are presented. Neutron radiography is compared with x-ray radiography for the cited examples, which include pyrotechnics and polyurethane insulation. (U.S.)

  9. Membrane facilitated separation of NF3 and CF4 / David Jacobus Branken.

    OpenAIRE

    Branken, David Jacobus

    2013-01-01

    Nitrogen trifluoride (NF3) is frequently used as a source of fluorine in the electronics device manufacturing industry as a dry etchant during plasma assisted etching of silicon wafers, or during the plasma cleaning of chemical vapor deposition chambers. As a result of the electrochemical synthesis procedures in which carbon anodes are used in a fluorine-rich environment, NF3 product streams are frequently contaminated with ppm-amounts of carbon tetrafluoride (CF4). The electronics manufactur...

  10. Sources

    International Nuclear Information System (INIS)

    This paper discusses the sources of radiation in the narrow perspective of radioactivity and the even narrow perspective of those sources that concern environmental management and restoration activities at DOE facilities, as well as a few related sources. Sources of irritation, Sources of inflammatory jingoism, and Sources of information. First, the sources of irritation fall into three categories: No reliable scientific ombudsman to speak without bias and prejudice for the public good, Technical jargon with unclear definitions exists within the radioactive nomenclature, and Scientific community keeps a low-profile with regard to public information. The next area of personal concern are the sources of inflammation. This include such things as: Plutonium being described as the most dangerous substance known to man, The amount of plutonium required to make a bomb, Talk of transuranic waste containing plutonium and its health affects, TMI-2 and Chernobyl being described as Siamese twins, Inadequate information on low-level disposal sites and current regulatory requirements under 10 CFR 61, Enhanced engineered waste disposal not being presented to the public accurately. Numerous sources of disinformation regarding low level radiation high-level radiation, Elusive nature of the scientific community, The Federal and State Health Agencies resources to address comparative risk, and Regulatory agencies speaking out without the support of the scientific community

  11. Potential impacts of CF3I on ozone as a replacement for CF3Br in aircraft applications

    Directory of Open Access Journals (Sweden)

    D. Youn

    2006-06-01

    Full Text Available Iodotrifluoromethane (CF3I has been considered to be a candidate replacement for bromotrifluoromethane (CF3Br, which is used in aircraft for fuel inerting and for fire fighting. In this study, the chemical effects of aircraft-released CF3I on atmospheric ozone were examined with the University of Illinois at Urbana-Champaign two-dimensional chemical-radiative-transport (UIUC 2-D CRT model. Using an earlier estimate of the aircraft emission profile for tank inerting in military aircraft, the resulting equivalent Ozone Depletion Potentials (ODPs for CF3I were in the range of 0.07 to 0.25. As a sensitivity study, we also analyzed CF3I emissions associated with fuel inerting if it were to occur at lower altitudes using an alternative estimate. The model calculations of resulting effects on ozone for this case gave ODPs≤0.05. Furthermore, through interactions with the National Institute of Standards and Technology (NIST, we analyzed the potential effects on ozone resulting from using CF3I in fire fighting connected with engine nacelle and auxiliary power unit applications. The scenarios evaluated using the NIST estimate suggested that the ODPs obtained by assuming aircraft flights occurring in several different latitude regions of the Northern Hemisphere are extremely low. According to the model calculation, the altitude where CF3I is released from aircraft is a dominant factor in its ozone depletion effects. On the assumption that the CF3I emission profile is representative of actual release characteristics, aircraft-released CF3I has much lower impacts on the ozone layer and can be a qualified substitute of CF3Br in engine nacelles.

  12. Strength and fatigue measurements for CfC materials

    International Nuclear Information System (INIS)

    CfC-materials are considered as candidate materials for the divertors of fusion reactors as well as for protecting tiles of the first wall. As a consequence of cyclic thermal loading the mechanical failure modes will be spontaneous failure due to exceeding of the limit of strength and failure caused by cyclic fatigue. These two failure modes are of main interest to the experimental investigations on CfC-materials. The mechanical behaviour of several CfC-materials was studied applying different types of testing: strength measurements, determination of fatigue and recording of crack-resistance curves. (orig.)

  13. Halogenation effects on electron collisions with CF3Cl, CF2Cl2, and CFCl3

    Science.gov (United States)

    Freitas, T. C.; Lopes, A. R.; Azeredo, A. D.; Bettega, M. H. F.

    2016-04-01

    We report differential and integral elastic cross sections for low-energy electron collisions with CF3Cl, CF2Cl2, and CFCl3 molecules for energies ranging from 0.1 eV to 30 eV. The calculations were performed using the Schwinger multichannel method with pseudopotentials in the static-exchange and static-exchange plus polarization approximations. The influence of the permanent electric dipole moment on the cross sections was included using the Born closure scheme. A very good agreement between our calculations and the experimental results of Jones [J. Chem. Phys. 84, 813 (1986)], Mann and Linder [J. Phys. B 25, 1621 (1992); 25, 1633 (1992)] and Hoshino et al. [J. Chem. Phys. 138, 214305 (2013)] was found. We also compare our results with the calculations of Beyer et al. [Chem. Phys. 255, 1 (2000)] using the R-matrix method, where we find good agreement with respect to the location of the resonances, and with the calculations of Hoshino et al. using the independent atom method with screening corrected additivity rule, where we find qualitative agreement at energies above 20 eV. Additional electronic structure calculations were carried out in order to help in the interpretation of the scattering results. The stabilization the lowest σ∗ resonance due to the exchange of fluorine by chlorine atoms (halogenation effect) follows a simple linear relation with the energy of the lowest unoccupied molecular orbitals and can be considered as a signature of the halogenation effect.

  14. Rotational Spectroscopy of Newly Detected Atmospheric Ozone Depleters: CF_3CH_2Cl, CF_3CCl_3, and CF_2ClCCl_3

    Science.gov (United States)

    Kisiel, Zbigniew; Bialkowska-Jaworska, Ewa; Pszczólkowski, Lech; Uriarte, Iciar; Ecija, Patricia; Basterretxea, Francisco J.; Cocinero, Emilio J.

    2015-06-01

    In a recent study of unpolluted air samples from Tasmania and of deep firn snow in Greenland four previously overlooked ozone-depleting substances have been identified. These compounds started to emerge in the atmosphere in the 1960s, and two: CF_3CCl_3 (CFC-113a) and CF_3CH_2Cl (HCHF-133a) continue to accumulate in the atmosphere. Three of the four compounds have non-zero dipole moments and are amenable to study by rotational spectroscopy, establishing the basis for analytic applications. Relatively limited studies have been reported for CF_3CH_2Cl and CF_3CCl_3, while CF_2ClCCl_3 has not yet been studied by this technique. We presently report extensive results obtained for all three compounds, resulting from concerted application of supersonic expansion FTMW spectroscopy in chirped pulse and cavity modes, and room-temperature MMW spectroscopy. Among the plentiful results, we have been able to resolve and fit the complex nuclear quadrupole hyperfine splitting. J.C.Laube, et al., Nature Geoscience 7, 266 (2014). Ogata, et al., J. Mol. Struct. 144, 1 (1986). R.Holm, et al., Z. Naturforsch. 23a, 1040 (1968). J.H.Carpenter et al., J. Mol. Spectrosc. 154, 207 (1992); P.J.Seo et al., J. Mol. Spectrosc. 169, 58 (1995).

  15. An absolute measurement of #-v# of Cf252

    International Nuclear Information System (INIS)

    An absolute measurement of v of Cf252. An absolute determination of the average number of neutrons, #-v#, emitted in the spontaneous fission of Cf252 has been made by counting the fission neutrons in a large liquid scintillator. The detection efficiency of this counter was measured as a function of neutron energy. Well-collimated neutrons were scattered into the scintillator by an anthracene crystal, which detected the corresponding recoil protons. Pulse-shape discrimination was employed to eliminate γ-ray background. The detection efficiency for Cf252 fission neutrons was found to be 0.703 ± 0.007, giving a value of 3.78 ± 0.04 for the average number of prompt neutrons emitted per Cf252 fission. (author)

  16. Properties of electron swarms in CF3I

    Science.gov (United States)

    Hasegawa, H.; Date, H.; Shimozuma, M.; Itoh, H.

    2009-09-01

    We report the electron swarm parameters, the drift velocity, and the ionization coefficients in CF3I gas for relatively wide ranges of reduced electric fields (E /N). The drift velocity is measured based on the arrival-time spectra of electrons for E /N=200-3000 Td, and the first and second ionization coefficients are determined by the steady-state Townsend method for E /N=400-5000 Td. The results are compared with those of CF4 to show that CF3I has a high reactivity for electron attachment in a low E /N region resulting in a much higher limiting E /N value (440 Td) than that of CF4.

  17. On the 252Cf primary and secondary gamma rays and epithermal neutron flux for BNCT

    Science.gov (United States)

    Ghassoun, J.; Merzouki, A.; El Morabiti, A.; Jehouani, A.

    2007-10-01

    Monte Carlo simulation has been used to calculate the different components of neutrons and secondary gamma rays originated by 252Cf fission and also the primary gamma rays emitted directly by the 252Cf source at the exit face of a compact system designed for the BNCT. The system consists of a 252Cf source and a moderator/reflector/filter assembly. To study the material properties and configuration possibilities, the MCNP code has been used. The moderator/reflector/filter arrangement is optimised to moderate neutrons to epithermal energy and, as far as possible, to get rid of fast and thermal neutrons and photons from the therapeutic beam. To reduce the total gamma contamination and to have a sufficiently high epithermal neutron flux we have used different photon filters of different thickness. Our analysis showed that the use of an appropriate filter leads to a gamma ray flux reduction without affecting the epithermal neutron beam quality at the exit face of the system.

  18. On the {sup 252}Cf primary and secondary gamma rays and epithermal neutron flux for BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Ghassoun, J. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, BP 2390, 40000 Marrakech (Morocco)], E-mail: ghassoun@ucam.ac.ma; Merzouki, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, BP 2390, 40000 Marrakech (Morocco); Remote Sensing and Geomatics of the Environnement Laboratory, Ottawa-Carleton Geoscience Centre, Marion Hall-140Louis Pasteur Ottawa, ON, KIN 6N5 (Canada); El Morabiti, A.; Jehouani, A. [LPTN, Departement de Physique, Faculte des Sciences Semlalia, BP 2390, 40000 Marrakech (Morocco)

    2007-10-15

    Monte Carlo simulation has been used to calculate the different components of neutrons and secondary gamma rays originated by {sup 252}Cf fission and also the primary gamma rays emitted directly by the {sup 252}Cf source at the exit face of a compact system designed for the BNCT. The system consists of a {sup 252}Cf source and a moderator/reflector/filter assembly. To study the material properties and configuration possibilities, the MCNP code has been used. The moderator/reflector/filter arrangement is optimised to moderate neutrons to epithermal energy and, as far as possible, to get rid of fast and thermal neutrons and photons from the therapeutic beam. To reduce the total gamma contamination and to have a sufficiently high epithermal neutron flux we have used different photon filters of different thickness. Our analysis showed that the use of an appropriate filter leads to a gamma ray flux reduction without affecting the epithermal neutron beam quality at the exit face of the system.

  19. On the 252Cf primary and secondary gamma rays and epithermal neutron flux for BNCT

    International Nuclear Information System (INIS)

    Monte Carlo simulation has been used to calculate the different components of neutrons and secondary gamma rays originated by 252Cf fission and also the primary gamma rays emitted directly by the 252Cf source at the exit face of a compact system designed for the BNCT. The system consists of a 252Cf source and a moderator/reflector/filter assembly. To study the material properties and configuration possibilities, the MCNP code has been used. The moderator/reflector/filter arrangement is optimised to moderate neutrons to epithermal energy and, as far as possible, to get rid of fast and thermal neutrons and photons from the therapeutic beam. To reduce the total gamma contamination and to have a sufficiently high epithermal neutron flux we have used different photon filters of different thickness. Our analysis showed that the use of an appropriate filter leads to a gamma ray flux reduction without affecting the epithermal neutron beam quality at the exit face of the system

  20. Test of the Bonner Sphere Spectrometer Response Matrix in the 252Cf Neutron Field

    International Nuclear Information System (INIS)

    Full text: Since its development in 1960, a Bonner sphere spectrometer (BSS) has been the only instrument, which enables the spectral neutron fluence to be measured in a wide range of energies from thermal up to 20 MeV. Its resolution is poor but sufficient for dosimetric specification of neutron fields at workplaces. Experimentally determined BSS count rates depends mainly on the accuracy of the response matrix characterising certain type of BSS. At presemt the BSS response matrices are calculate by neutron transport Monte Carlo codes which allow detailed description of the BSS setup. The best verification of calculated response matrix is a calibration of the BSS in fields of monoenergetic neutrons. As so as these fields are not simply achievable a simple method how to test quality of BSS response matrix in the neutron field of 252Cf source is described. Applying distance variation method we get count rates of the BSS in the 252Cf field from which contributions of scattered neutrons and influence of finite detector and source dimensions were removed. These count rates are compared with the integrals of pure 252Cf spectrum and responses for individual spheres of the BSS. Disagreement indicates for which sphere the response is not properly determined. (author)

  1. Imaging of primary and secondary radiation—Modelling and experimental results of a radioactive source and a water phantom

    International Nuclear Information System (INIS)

    In this paper the contribution of primary and secondary radiation from a water phantom to a pinhole volume, as a result of three neutron sources (Cf, AmBe and 5 MeV mono-energetic) and two gamma sources (Cs and Co), is separately estimated using the PTRAC particle tracking option available in MCNP. Also in this paper imaging of the mixed radiation field produced by a Van de Graaf accelerator (when a water phantom is present) is described. In the model, a spherical tally volume, 2 cm in diameter, was placed equidistantly from a radioactive source and 30×30×15 cm3 water phantom. Monte Carlo simulations have been carried out to investigate the level of primary and secondary radiation contributing to the pinhole volume directly from the source and from interactions in the phantom respectively. The spatial distribution of counts clearly discriminated the source and the phantom. The results have shown that the percentage of neutrons reflected from the phantom with energies above 1 MeV increases with mean energy of the source. This method has significant potential to characterise secondary radiation in proton therapy, where it would help to verify the location and the energy delivered during the treatment

  2. Survey of CF mutations in the clinical laboratory

    OpenAIRE

    Myers Angela; Nersesian Rhea; Mirkovic Borka; Huber Klaus; Saiki Randall; Bauer Kurt

    2002-01-01

    Abstract Background Since it is impossible to sequence the complete CFTR gene routinely, clinical laboratories must rely on test systems that screen for a panel of the most frequent mutations causing disease in a high percentage of patients. Thus, in a cohort of 257 persons that were referred to our laboratory for analysis of CF gene mutations, reverse line probe assays for the most common CF mutations were performed. These techniques were evaluated as routine first-line analyses of the CFTR ...

  3. CF3SF5 : a ‘super’ greenhouse gas

    OpenAIRE

    Tuckett, R. P.

    2008-01-01

    One molecule of the anthropogenic pollutant trifluoromethyl sulphur pentafluoride (CF\\(_3\\)SF\\(_5\\)), an adduct of the CF\\(_3\\) and SF\\(_5\\) free radicals, causes more global warming than one molecule of any other greenhouse gas yet detected in the Earth’s atmosphere. That is, it has the highest per molecule radiative forcing of any greenhouse pollutant, and the value of its global warming potential is only exceeded by that of SF\\(_6\\). First, the greenhouse effect is described, the propertie...

  4. Performance evaluation of high-pressure MWPC with individual line readout under Cf-252 neutron irradiation

    International Nuclear Information System (INIS)

    A multiwire proportional chamber (MWPC) neutron detector system was developed for the Materials and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex. Its basic performance was evaluated by an irradiation experiment using a Cf-252 neutron source. A short response time and high spatial resolution can be obtained using an individual line readout method. The detector system exhibited a one-dimensional uniformity of response of 4.8% and 3.8% in the x- and y-directions, respectively. The uniformity of all pixels in the two-dimensional image was 7.9%. The average intrinsic spatial resolution was 1.55 mm full width at half maximum in the sensitive region calculated by taking into account the track lengths of secondary particles. The signal intensity of the system remained constant during the operation for 500 min under Cf-252 neutron irradiation.

  5. Proportional counters aged anode wire recovering using an 80%CF4 + 20%CO2 gas mixture

    CERN Document Server

    Gavrilov, Gennady; Conti, Richard; Fetisov, Andrey; Maysuzenko, Dmitry; Shvecova, Natalia; Vakhtel, Victor

    2011-01-01

    A technique to recover a gas proportional counter having an aged anode wire using a glow discharge in an 80%CF4 + 20%CO2 gas mixture has been developed and tested. Studies of aging effects were carried out under sustained irradiation by an intense 90Sr -source of the straw proportional counters operated with a 60%Ar + 30%CO2 + 10%CF4 gas mixture. Special attention was paid to the aging mechanism of the anode wires. Our experience showed that using a given gas mixture the swelling of the anode wires is a typical mode of aging that leads to degradation of the gas gain. The proposed method of recovery provided a complete restoration of the gas gain and the signal amplitude in the damaged zone of the wire. SEM/XEM analysis confirmed successful cleaning WOx deposits from the wire surface. The application of this method to recover the aged gaseous detectors in real experimental conditions is discussed.

  6. Test and evaluation results of the 252Cf shuffler at the Savannah River Plant

    International Nuclear Information System (INIS)

    The 252Cf Shuffler, a nondestructive assay instrument employing californium neutron source irradiation and delayed-neutron counting, was developed for measuring 235U content of scrap and waste items generated at the Savannah River Plant (SRP) reactor fuel fabrication facility. The scrap and waste items include high-purity uranium-aluminum alloy ingots as well as pieces of castings, saw and lathe chips from machining operations, low-purity items such as oxides of uranium or uranium intermixed with flux materials found in recovery operations, and materials not recoverable at SRP such as floor sweepings or residues from the uranium scrap recovery operation. The uranium contains about 60% 235U with the remaining isotopes being 236U, 238U, and 234U in descending order. The test and evaluation at SRP concluded that the accuracy, safety, reliability, and ease of use made the 252Cf Shuffler a suitable instrument for routine use in an industrial, production-oriented plant

  7. Cf-252 based neutron radiography using real-time image processing system

    International Nuclear Information System (INIS)

    For compact Cf-252 based neutron radiography, a real-time image processing system by particle counting technique has been developed. The electronic imaging system consists of a supersensitive imaging camera, a real-time corrector, a real-time binary converter, a real-time calculator for centroid, a display monitor and a computer. Three types of accumulated NR image; ordinary, binary and centroid images, can be observed during a measurement. Accumulated NR images were taken by the centroid mode, the binary mode and ordinary mode using of Cf-252 neutron source and those images were compared. The centroid mode presented the sharpest image and its statistical characteristics followed the Poisson distribution, while the ordinary mode showed the smoothest image as the averaging effect by particle bright spots with distributed brightness was most dominant. (author)

  8. Sources

    OpenAIRE

    2015-01-01

    Sources Fondation Pablo Iglesias. Alcala de Henares. Sections : Archives privées de Manuel ArijaArchives extérieuresArchives FNJS de EspañaPrensa Archives Générales de l’Administration. Alcala de Henares. Sections : Opposition au franquismeSig. 653 Sig TOP 82/68.103-68.602.Índice de las cartas colectivas, Relaciones, Cartas al Ministro de Información de Marzo de 1965. c.662. Sources cinématographiques Filmothèque Nationale d’Espagne.NO.DO. N° 1157C. 08/03/1965.aguirre Javier, Blanco vertical....

  9. Preparation and synthetic applications of aryl tetraflates (ArOSO2CF2CF2H).

    Science.gov (United States)

    Rostovtsev, Vsevolod V; Bryman, Lois M; Junk, Christopher P; Harmer, Mark A; Carcani, Liane G

    2008-01-18

    We have recently developed an improved synthetic route to 1,1,2,2-tetrafluoroethanesulfonic acid (HCF2CF2SO3H, TFESA) and explored the applications of this newly available superacid in catalysis. Low volatility, ease of handling, and a convenient 1H NMR handle make this acid an attractive alternative to triflic acid. TFESA can also be converted to several of its derivatives: anhydride, sulfonyl chloride, and sulfonyl fluoride, which provide a good entry point for the synthesis of aryl sulfonates. We prepared several aryl esters of 1,1,2,2-tetrafluoroethanesulfonic acid (aryl tetraflates) and showed that they can be used in a number of palladium-catalyzed coupling reactions (Suzuki, Heck, and Buchwald-Hartwig couplings). While the reactivity of tetraflates lies between that of triflates and chlorides, tetraflates appear to be more thermally stable. Additionally, the presence of a hydrogen atom in the tetraflate group facilitates monitoring of reactions and characterization of derivatives. PMID:18085791

  10. Effects of neutron source selection on land-mine detection efficiency

    International Nuclear Information System (INIS)

    One proposed method of land-mine detection is based on measurements of the 10.8 MeV photons from the 14N(n, γ) reaction. In this study, simulations of the photon production efficiencies for nitrogenous explosive material (TNT), buried in soil having variable moisture content, were completed for different published neutron spectra. Monte Carlo simulations were performed with MCNP with a cylindrical geometry of TNT considered as target material and with neutron energies ranging from thermal to 20 MeV. The numbers of 14N(n, γ) reactions in TNT were tallied to obtain response functions. To find the effectiveness of different neutron sources, response functions were folded with the neutron spectra. Response curves reveal that higher water content increases response for fast neutrons, and reduces response for slow neutrons. Lower energy neutron sources, i.e. D(d, n) or 252Cf, are more suitable than higher energy neutron sources such as 241Am-Be or T(d, n). Although its advantages disappear with increasing depth, the usage of moderating spheres of CH2 increases the signal significantly when compared with a bare source, while also reducing neutron dose to workers

  11. A cohort study of the Copenhagen CF Centre eradication strategy against Staphylococcus aureus in patients with CF

    DEFF Research Database (Denmark)

    Dalbøge, Christina Schjellerup; Pressler, Tacjana; Høiby, Niels;

    2013-01-01

    Staphylococcus aureus is an important pathogen in CF. Centre prevalence of intermittent colonization and chronic S. aureus infections and the effectiveness of an anti-S. aureus eradication strategy was assessed....

  12. Photoinitiated Oxidative Addition of CF3I to Gold(I) and Facile Aryl-CF3 Reductive Elimination

    OpenAIRE

    Winston, Matthew S.; William J. Wolf; Toste, F. Dean

    2014-01-01

    Herein we report the mechanism of oxidative addition of CF3I to Au(I), and remarkably fast Caryl–CF3 bond reductive elimination from Au(III) cations. CF3I undergoes a fast, formal oxidative addition to R3PAuR′ (R = Cy, R′ = 3,5-F2-C6H4, 4-F-C6H4, C6H5, 4-Me-C6H4, 4-MeO-C6H4, Me; R = Ph, R′ = 4-F-C6H4, 4-Me-C6H4). When R′ = aryl, complexes of the type R3PAu(aryl)(CF3)I can be isolated and characterized. Mechanistic studies suggest that near-ultraviolet light (λmax = 313 nm) photoinitiates a ra...

  13. Atmospheric chemistry of CF3O2: a theoretical study on mechanisms and pathways of the CF3O2 + IO reaction.

    Science.gov (United States)

    Li, Hongwei; Tang, Yizhen; Wang, Rongshun

    2013-04-28

    The mechanisms and reaction pathways for the CF3O2 + IO reaction have been investigated by quantum chemistry methods. It has been found that the title reaction takes place on both the singlet and triplet potential energy surfaces (PES). On the singlet PES, the most important products include CF3OOOI, CF3OOIO, CF3OIO2, and CF2O + FIO2, while other products such as CF2O + FOIO, CF2O + FOOI, CF3OOI + O((3)P), CF3OI + O2 ((1)Δ and (3)Σ), and CF3O + OIO are negligible due to high barriers or unstable formations. On the triplet PES, CF3O + OIO is the dominant product with a lower barrier. As for FIO2 and it isomers, the most stable one is FIO2. TDDFT (Time Dependent Density Functional Theory) calculation indicates that CF3OOOI, CF3OOIO and CF3OIO2 undergo photolysis easily under sunlight. Moreover, a minor contribution relative to hydrogen is found in the CX3O2 + IO (X = H and F) reactions. PMID:23493819

  14. 76 FR 14796 - Airworthiness Directives; General Electric Company CF6-45 and CF6-50 Series Turbofan Engines

    Science.gov (United States)

    2011-03-18

    ...We are superseding an existing airworthiness directive (AD) for General Electric Company (GE) CF6-45 and CF6-50 series turbofan engines. That AD currently requires replacing certain forward and aft centerbodies of the long fixed core exhaust nozzle (LFCEN) assembly. This AD adds certain new forward and aft centerbody part numbers (P/Ns) to the list requiring replacement. This AD was prompted......

  15. 76 FR 6323 - Airworthiness Directives; General Electric Company CF6-45 and CF6-50 Series Turbofan Engines

    Science.gov (United States)

    2011-02-04

    ...We are superseding an existing airworthiness directive (AD) for General Electric Company (GE) CF6-45 and CF6-50 series turbofan engines with certain low-pressure turbine (LPT) rotor stage 3 disks installed. That AD currently requires initial and repetitive borescope inspections of the high-pressure turbine (HPT) rotor stage 1 and stage 2 blades for wear and damage, including excessive airfoil......

  16. Survey of CF mutations in the clinical laboratory

    Directory of Open Access Journals (Sweden)

    Myers Angela

    2002-11-01

    Full Text Available Abstract Background Since it is impossible to sequence the complete CFTR gene routinely, clinical laboratories must rely on test systems that screen for a panel of the most frequent mutations causing disease in a high percentage of patients. Thus, in a cohort of 257 persons that were referred to our laboratory for analysis of CF gene mutations, reverse line probe assays for the most common CF mutations were performed. These techniques were evaluated as routine first-line analyses of the CFTR gene status. Methods DNA from whole blood specimens was extracted and subjected to PCR amplification of 9 exons and 6 introns of the CFTR gene. The resulting amplicons were hybridised to probes for CF mutations and polymorphisms, immobilised on membranes supplied by Roche Molecular Systems, Inc. and Innogenetics, Inc.. Denaturing gradient gel electrophoresis and sequencing of suspicious fragments indicating mutations were done with CF exon and intron specific primers. Results Of the 257 persons tested over the last three years (referrals based on 1 clinical symptoms typical for/indicative of CF, 2 indication for in vitro fertilisation, and 3 gene status determination because of anticipated parenthood and partners or relatives affected by CF, the reverse line blots detected heterozygote or homozygote mutations in the CFTR gene in 68 persons (26%. Eighty-three percent of those affected were heterozygous (47 persons or homozygous (10 persons for the ΔF508 allele. The only other CF-alleles that we found with these tests were the G542X allele (3 persons, the G551D allele (3 persons, the 3849+10kb C-T allele (2 persons the R117H allele (2 persons and the 621+1G-T allele (1 person. Of the fifteen IVS8-5T-polymorphisms detected in intron 8, seven (47% were found in males referred to us from IVF clinics. These seven 5T-alleles were all coupled with a heterozygous ΔF508 allele, they make up 35% of the males with fertility problems (20 men referred to us. Conclusions

  17. Decomposition of Potent Greenhouse Gases SF6, CF4 and SF5CF3 by Dielectric Barrier Discharge

    Science.gov (United States)

    Zhang, Renxi; Wang, Jingting; Cao, Xu; Hou, Huiqi

    2016-04-01

    For their distinguished global warming potential (GWP100) and long atmosphere lifespan, CF4, SF6 and SF5CF3 were significant in the field of greenhouse gas research. The details of discharging character and the optimal parameter were discussed by using a Dielectric Barrier Discharge (DBD) reactor to decompose these potent greenhouse gases in this work. The results showed that SF6 could be decomposed by 92% under the conditions of 5 min resident time and 3000 V applied voltage with the partial pressure of 2.0 kPa, 28.2 kPa, and 1.8 kPa for SF6, air and water vapor, respectively. 0.4 kPa CF4 could be decomposed by 98.2% for 4 min resident time with 30 kPa Ar added. The decomposition of SF5CF3 was much more effective than that of SF6 and CF4 and moreover, 1.3 kPa SF5CF3, discharged with 30 kPa O2, Ar and air, could not be detected when the resident time was 80 s, 40 s, and 120 s, respectively. All the results indicated that DBD was a feasible technique for the abatement of potent greenhouse gases. supported by National Natural Science Foundation of China (Nos. 20507004, 21577023)

  18. Kinetic and thermodynamic behaviour of CF4 clathrate hydrates

    International Nuclear Information System (INIS)

    Highlights: • The kinetics and thermodynamics of CF4 hydrates are investigated. • Experimental hydrate dissociation conditions for CF4 are reported. • Good agreement between the experimental data and model predictions is observed. • The effect of initial conditions (T and P) on the CF4 hydrate kinetics is studied. - Abstract: This study presents experimental kinetic and thermodynamic data for CF4 clathrate hydrates. Experimental measurements were undertaken in a high pressure equilibrium cell with a 40 cm3 inner volume. The measurements of experimental hydrate dissociation conditions were performed in the temperature range of (273.8 to 278.3) K and pressures ranging from (4.55 to 11.57) MPa. A thermodynamic model based on van der Waals and Platteeuw (vdW–P) solid solution theory was used for prediction and comparison of hydrate dissociation conditions and the Langmuir constant parameters for CF4 based on Parrish and Prausnitz equation are reported. For the kinetics, the effect of initial pressure and temperature on the induction time, CF4 hydrate formation rate, the apparent rate constant of reaction, storage capacity, and water to hydrate conversion during the hydrate formation were studied. Kinetic experiments were performed at initial temperatures of (275.3, 276.1 and 276.6) K and initial pressures of (7.08, 7.92, 9.11, 11.47 and 11.83) MPa. Results show that increasing the initial pressure at constant temperature decreases the induction time, while CF4 hydrate formation rate, the apparent rate constant of reaction, storage capacity, and water to hydrate conversion increase. The same trends are observed with a decrease in the initial temperature at constant pressure

  19. Sources

    OpenAIRE

    2011-01-01

    A. SOURCES STATISTIQUES 1. Statistiques générales Annuaire statistique international, SDN (à partir de 1926). Mémorandum sur le commerce international et sur les balances des paiements, annuel à partir de 1927 (numéros rétrospectifs 1912-1926, 1913-1927), [3 volumes : aperçu général ; balances des paiements ; statistiques du commerce extérieur ; utilise les données nationales disponibles. Très utile]. Annuaire statistique de la France. Annuaire statistique de la Belgique. Statistiques économi...

  20. Sources

    OpenAIRE

    2013-01-01

    I–SOURCES MANUSCRITES Archivio di Stato di Roma (ASR) Presidenza dell’Annona e Grascia : bb. 67-68, Lista dei misuratori del grano, 1658-1660. bb. 352-377, Nota dei grani introdotti e venduti in Roma, 1657-1715. bb. 412-419, Ristretto delle assegne dei grani date dai mercanti, 1680-1687. b. 1470, Registro delle lettere del Prefetto dell’Annona, 1659-1660. b. 1706, Libri di entrata e uscita dei grani dell’abbondanza (Ripetta), 16581670. bb. 1930-1931, Debiti e crediti dei fornai, 1658-1660. b....

  1. Sources

    OpenAIRE

    2014-01-01

    Sources éditées : ABADAL i de VINYALS, Ramon d', Catalunya carolingia, II, Els diplomes carolingis a Catalunya, 2 vol., Barcelone, 1926-1952, cit. CC. ACHERY, D', Luc, Spicilegium sive collectio veterum aliquot scriptorum..., E. Baluze et E. Martène éd., Paris, 1723, tome 3. ALART, Bernard, Privilèges et titres relatifs aux franchises, institutions et propriétés communales de Roussillon et de Cerdagne depuis le xie siècle jusqu 'à l'an 1660... Première partie, Perpignan, 1878. ALART, Bernard,...

  2. Averaged U238 fission cross section measurement in Cf-252 neutron spectrum

    International Nuclear Information System (INIS)

    With regard to the standardization of Cf-252 neutron spectrum, the averaged U-238 fission cross section was measured over the Cf-252 neutron spectrum using foil activation technique. The gamma spectra of the fission products were obtained on a pure germanium detector at different decay times in order to identify the gamma rays of short, medium and long half-life radioisotopes. Analyzing the gamma spectra of the irradiated uranium foils several distinct photopeaks of several fission products were identified. The pure activity of Te-132 was determined from the net area under 228.2 kev photopeak after correcting it for neighbouring photopeaks of Np-239 and Pa-234. The averaged U238 fission cross section was calculated from the corrected counts of Te-132 photopeak to be 329±10 mb. The main sources of errors in the measurements are mainly due to inaccuracy of location of foils, neutron flux, counting statistics, weight of foils, impurity of foils and interference from neighbouring photopeaks. The contribution of fission neutrons from spontaneous fission of Cm-248, daughter of Cf-252, to the total flux density was estimated at 0.13%. (orig.)

  3. Isotopic yield in alpha accompanied ternary fission of 252Cf

    International Nuclear Information System (INIS)

    The cold ternary fission of 252Cf with 4He as light charged particle (LCP) is studied with fragments in the equatorial and collinear configuration, taking the interacting barrier as the sum of the Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot and by calculating the yield for charge-minimized fragments. In both equatorial and collinear configurations, the highest yield is obtained for the fragment combination 116Pd + 4He + 132Sn, which possess doubly magic nuclei 132Sn(N = 82, Z = 50). The presence of doubly or near doubly magic nuclei (132Sn, 130Sn etc.) and higher Q value plays an important role in the alpha accompanied cold ternary fission of 252Cf. The comparison of the relative yield for equatorial configuration with that of collinear configuration, points to the fact that equatorial configuration is the preferred configuration for the LCP (4He) accompanied ternary fission in 252Cf isotope. The yields obtained for the alpha accompanied cold ternary fission of 252Cf in equatorial and collinear configuration are compared with the experimental data. The emission probability of long range alpha (LRA) particle from 252Cf isotope is predicted using our formalism and is found to be in agreement with experimental value. (author)

  4. CfA3: 185 Type Ia Supernova Light Curves from the CfA

    CERN Document Server

    Hicken, Malcolm; Jha, Saurabh; Kirsher, Robert P; Matheson, Tom; Modjaz, Maryam; Rest, Armin; Wood-Vasey, W Michael

    2009-01-01

    We present multi-band photometry of 185 type-Ia supernovae (SN Ia), with over 11500 observations. These were acquired between 2001 and 2008 at the F. L. Whipple Observatory of the Harvard-Smithsonian Center for Astrophysics (CfA). This sample contains the largest number of homogeneously-observed and reduced nearby SN Ia (z < 0.08) published to date. It more than doubles the nearby sample, bringing SN Ia cosmology to the point where systematic uncertainties dominate. Our natural system photometry has a precision of 0.02 mag or better in BVRIr'i' and roughly 0.04 mag in U for points brighter than 17.5 mag. We also estimate a systematic uncertainty of 0.03 mag in our SN Ia standard system BVRIr'i' photometry and 0.07 mag for U. Comparisons of our standard system photometry with published SN Ia light curves and comparison stars, where available for the same SN, reveal agreement at the level of a few hundredths mag in most cases. We find that 1991bg-like SN Ia are sufficiently distinct from other SN Ia in their...

  5. 235Cf anti ν discrepancy and the sulfur discrepancy

    International Nuclear Information System (INIS)

    The cantankerous discrepancy among measured values of anti ν for 235Cf appears at last to be nearing a final resolution. A recent review has summarized the progress that has been achieved through revaluation upward by 0.5% of two manganese bath values anti ν and the performance of a new liquid scintillator measurement. A new manganese bath measurement at INEL is in reasonably good agreement with previous manganese bath values of 235Cf anti ν. It now appears that the manganese bath values could still be systematically low by as much as 0.4% because the BNL-325 thermal absorption cross section for sulfur may be as much as 10% low. There is a bona fide discrepancy between measurements of the sulfur cross section by pile oscillators and the values derived from transmission measurements. The resolution of this discrepancy is a prerequisite to the final resolution of the 235Cf anti ν discrepancy. 22 references

  6. Microscopic description of Cf-252 cold fission yields

    OpenAIRE

    Mirea, M.; Delion, D. S.; Sandulescu, A.

    2009-01-01

    We investigate the cold fission of 252Cf within the two center shell model to compute the potential energy surface. The fission yields are estimated by using the semiclassical penetration approach. It turns out that the inner cold valley of the total potential energy is strongly connected with Z=50 magic number. The agreement with experimental values is very much improved only by considering mass and charge asymmetry degrees of freedom. Thus, indeed cold fission of 252Cf is a Sn-like radioact...

  7. Quenching the scintillation in CF4 Cherenkov gas radiator

    International Nuclear Information System (INIS)

    CF4 is used as a Cherenkov gas radiator in one of the Ring Imaging Cherenkov detectors at the LHCb experiment at the CERN Large Hadron Collider. CF4 is well known to have a high scintillation photon yield in the near and far VUV, UV and in the visible wavelength range. A large flux of scintillation photons in our photon detection acceptance between 200 and 800 nm could compromise the particle identification efficiency. We will show that this scintillation photon emission system can be effectively quenched, consistent with radiationless transitions, with no significant impact on the photons resulting from Cherenkov radiation

  8. Theoretical analysis of the Cf-252 fission neutron spectrum

    International Nuclear Information System (INIS)

    A complex cascade evaporation model is used to analyse energy and angular distributions of Cf-252 fission neutrons for specified scission configurations. The sensitivity of the calculation with regard to the most important input data as well as certain approximations has been studied for typical fragment mass numbers. The paper includes a brief summary on the characteristics of the scission neutron component and its influence on energy spectra and angular distributions of fission neutrons. The model was also applied to calculate the distortion of the measurable Cf-252 fission neutron spectrum by the anisotropic fragment detection in time-of-flight spectrometer arrangements. (author)

  9. How to pass higher physics for CfE

    CERN Document Server

    Chambers, Paul; Mitchell, John

    2014-01-01

    Get your best grade with this guide to Higher Physics for CfE. We are working with SQA to gain endorsement for this title. This book contains all the advice and support you need to revise successfully for your Higher (for CfE) exam. It combines an overview of the course syllabus with advice from a top expert on how to improve exam performance, so you have the best chance of success. - Refresh your knowledge with complete course notes. - Prepare for the exam with top tips and hints on revision techniques. - Get your best grade with advice on how to gain those vital extra marks

  10. Radioactive Beams from 252CF Fission Using a Gas Catcher and an ECR Charge Breeder at ATLAS

    CERN Document Server

    Pardo, Richard C; Hecht, Adam; Moore, Eugene F; Savard, Guy

    2005-01-01

    An upgrade to the radioactive beam capability of the ATLAS facility has been proposed using 252Cf fission fragments thermalized and collected into a low-energy particle beam using a helium gas catcher. In order to reaccelerate these beams an existing ATLAS ECR ion source will be reconfigured as a charge breeder source. A 1Ci 252Cf source is expected to provide sufficient yield to deliver beams of up to ~106 far from stability ions per second on target. A facility description, the expected performance and the expected performance will be presented in this paper. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract W-31-109-ENG-38.

  11. Measurement of reflect neutron for 252Cf in cement cylinder by method of 235U fission

    International Nuclear Information System (INIS)

    The experiment theory of Research of neutron reflected coefficient for 252Cf in cement reflector was introduced. The fission rate of 235U with reflector, without reflector and with background was measured. The neutron reflected coefficient with cement reflector was concluded from fission rate and the reflected coefficient for different neutron source in the same experiment model was compared. The relation of reflected coefficient with angle was analyzed. The technology of solid track was researched and the best etch condition was explored. The trend of discharge count with coders thickness and etch thickness was gained. Efficiency for spark auto counters was measured and the technology of solid track was developed. (authors)

  12. Absorption cross section measurements for 252Cf spontaneous fission neutrons (LWBR development program)

    International Nuclear Information System (INIS)

    Absolute absorption cross sections have been measured for 232Th and 197Au for 252Cf spontaneous fission neutrons. Irradiations were performed in an exceptionally low mass source-foil arrangement, providing a ''pure'' spectrum with few corrections. Calibration of the activation detector was achieved by irradiating identical foils in the National Bureau of Standards (NBS) Standard Thermal Flux. A simple ratio technique was also used to obtain an independent estimate of the relative 232Th to 197Au integral cross sections, yielding a value in good agreement with that above. This technique was extended to 181Ta, 98Mo, and 63Cu. (5 tables, 3 figures) (U.S.)

  13. Two-Phase Flow Measurements with 252Cf: Design Aspects and Considerations

    International Nuclear Information System (INIS)

    For many years 252Cf has been used for measuring moisture content, particularly in the ground's soil, by detecting the amount of slowing down (thermalization) of the source's fission neutrons by the hydrogen nuclei in water. The same concept has been employed for measuring the phase volume fraction in two-phase flows. Although the principle of using neutron slowing down to measure hydrogen content is basic and straightforward, its application in a confined and evolving medium such as two-phase flow can be challenging. This paper identifies some of these challenges and presents some approaches for dealing with them

  14. Feasibility of subcriticality and NDA measurements for spent fuel by frequency analysis techniques with 252Cf

    International Nuclear Information System (INIS)

    The 252Cf-source-driven frequency analysis method can be used for measuring the subcritical neutron multiplication factor of arrays of LWR fuel and as little as a single PWR fuel assembly. These measurements can be used to verify the criticality safety margins of spent LWR fuel configurations and thus could be a means of obtaining the information to justify burnup credit for spent LWR transportation/storage casks. In addition, the data can be used to validate calculational methods for criticality safety. These measurements provide parameters that have a higher sensitivity to changes in fissile mass than neutron multiplication factor and thus serve as a better test of calculational methods. The analysis have also shown that measurement of the cross power spectral density (CPSD) between detectors on one side of a single fuel assembly and an internal or external 252Cf source driving the fission chain multiplication process can be used for nondestructive assay of fissile mass along the length of the assembly. This CPSD is a smooth function of fissile mass and does not depend on the varying inherent source in the fuel assembly and thus is ideal for fissile mass assay

  15. A restructuring of CF package for MIDAS computer code

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. H.; Kim, K. R.; Kim, D. H.; Cho, S. W. [KAERI, Taejon (Korea, Republic of)

    2004-07-01

    CF package, which evaluates user-specified 'control functions' and applies them to define or control various aspects of computation, has been restructured for the MIDAS computer code. MIDAS is being developed as an integrated severe accident analysis code with a user-friendly graphical user interface and modernized data structure. To do this, data transferring methods of current MELCOR code are modified and adopted into the CF package. The data structure of the current MELCOR code using FORTRAN77 causes a difficult grasping of meaning of the variables as well as waste of memory, difficulty is more over because its data is location information of other package's data due to characteristics of CF package. New features of FORTRAN90 make it possible to allocate the storage dynamically and to use the user-defined data type, which lead to an efficient memory treatment and an easy understanding of the code. Restructuring of the CF package addressed in this paper includes module development, subroutine modification, and treats MELGEN, which generates data file, as well as MELCOR, which is processing a calculation. The verification has been done by comparing the results of the modified code with those from the existing code. As the trends are similar to each other, it hints that the same approach could be extended to the entire code package. It is expected that code restructuring will accelerate the code domestication thanks to direct understanding of each variable and easy implementation of modified or newly developed models.

  16. The 252Cf neutron spectrum in ISO Standard 8529

    International Nuclear Information System (INIS)

    The provenance of the 252Cf neutron spectrum tabulated in ISO Standard 8529 Part 1 is discussed in the light of queries raised in an earlier ESARDA article. It is shown that neither the ISO spectrum nor a Maxwellian representation is compatible with the most recent evaluation of this important standard spectrum.

  17. A restructuring of CF package for MIDAS computer code

    International Nuclear Information System (INIS)

    CF package, which evaluates user-specified 'control functions' and applies them to define or control various aspects of computation, has been restructured for the MIDAS computer code. MIDAS is being developed as an integrated severe accident analysis code with a user-friendly graphical user interface and modernized data structure. To do this, data transferring methods of current MELCOR code are modified and adopted into the CF package. The data structure of the current MELCOR code using FORTRAN77 causes a difficult grasping of meaning of the variables as well as waste of memory, difficulty is more over because its data is location information of other package's data due to characteristics of CF package. New features of FORTRAN90 make it possible to allocate the storage dynamically and to use the user-defined data type, which lead to an efficient memory treatment and an easy understanding of the code. Restructuring of the CF package addressed in this paper includes module development, subroutine modification, and treats MELGEN, which generates data file, as well as MELCOR, which is processing a calculation. The verification has been done by comparing the results of the modified code with those from the existing code. As the trends are similar to each other, it hints that the same approach could be extended to the entire code package. It is expected that code restructuring will accelerate the code domestication thanks to direct understanding of each variable and easy implementation of modified or newly developed models

  18. Cure of cervical cancer using 252Cf neutron brachytherapy

    International Nuclear Information System (INIS)

    252Cf neutron brachytherapy was tested in a feasibility trial for efficacy for cervix cancer therapy vs. high stage radioresistant and subsequently for all stages of disease. Actuarial survival curves were analyzed for 218 patients treated between 1976 and 1983 and followed five to 14 years to the present time. A variety of doses, schedules and methods for brachytherapy was tested during this period, and a dose-response relationship for tumor eradication studied. All treatments were combined with whole-pelvis photon radiotherapy to approximately 45 to 60 Gy. This combination was found effective, particularly if an early implant schedule was used for the Cf implant, followed by whole-pelvis photon radiotherapy. For bulk/barrel shaped low-stage disease in medically fit patients, 252Cf implants were combined with surgery, i.e., extrafascial hysterectomy and was readily usable for treatment without complications and with high cure rates (92% five-year survival). All survivals and outcomes to 13 years match the best results of conventional photon radiotherapy. For all stages better results were observed for bulky, barrel, and advanced-stage tumors, especially for local tumor control, if optimal schedules, doses and implant numbers were used. Knowledge about neutron dose, dose per implant, number of implants and combination with photon beam therapy evolved during the trials. 252Cf represents a new quickacting effective radioisotope for human cancer therapy especially for treatment of radioresistant, bulky and high stage cancers. (orig.)

  19. Vibrational spectrum of CF4 isotopes in an algebraic model

    Indian Academy of Sciences (India)

    Joydeep Choudhury; Srinivasa Rao Karumuri; Nirmal Kumar Sarkar; Ramendu Bhattacharjee

    2009-11-01

    n this paper the stretching vibrational modes of CF4 isotopes are calculated up to first overtone using the one-dimensional vibron model for the first time. The model Hamiltonian so constructed seems to describe the C–F stretching modes accurately using a relatively small set of well-defined parameters.

  20. Californium-252 neutron sources

    International Nuclear Information System (INIS)

    Major production programs for the Savannah River reactors and the High Flux Isotopes Reactor at Oak Ridge have made 252Cf one of the most available and, at the USAEC's sales price of $10/μg, one of the least-expensive isotopic neutron sources. Reactor production has totaled approximately 2 g, and, based on expected demand, an additional 10 g will be produced in the next decade. The approximately 800 mg chemically separated to date has been used to prepare over 600 neutron sources. Most, about 500, have been medical sources containing 1 to 5 μg of 252Cf plated in needles for experimental cancer therapy studies. The remainder have generally been point sources containing 10 μg to 12 mg of oxide for activation, well logging, or radiography uses. Bulk sources have also been supplied to the commercial encapsulators. The latest development has been the production of 252Cf cermet wire which can be cut into almost contamination-free lengths of the desired 252Cf content. Casks are available for transport of sources up to 50 mg. Subcritical assemblies have been developed to multiply the source neutrons by a factor of 10 to 40, and collimators and thermalizers have also been extensively developed to shape the neutron flux and energy distributions for special applications. (U.S.)

  1. Dosimetric analysis of BNCT - Boron Neutron Capture Therapy - coupled to 252Cf brachytherapy

    International Nuclear Information System (INIS)

    The incidence of brain tumors is increasing in world population; however, the treatments employed in this type of tumor have a high rate of failure and in some cases have been considered palliative, depending on histology and staging of tumor. Its necessary to achieve the control tumor dose without the spread irradiation cause damage in the brain, affecting patient neurological function. Stereotactic radiosurgery is a technique that achieves this; nevertheless, other techniques that can be used on the brain tumor control must be developed, in order to guarantee lower dose on health surroundings tissues other techniques must be developing. The 252Cf brachytherapy applied to brain tumors has already been suggested, showing promising results in comparison to photon source, since the active source is placed into the tumor, providing greater dose deposition, while more distant regions are spared. BNCT - Boron Neutron Capture Therapy - is another technique that is in developing to brain tumors control, showing theoretical superiority on the rules of conventional treatments, due to a selective irradiation of neoplasics cells, after the patient receives a borate compound infusion and be subjected to a epithermal neutrons beam. This work presents dosimetric studies of the coupling techniques: BNCT with 252Cf brachytherapy, conducted through computer simulation in MCNP5 code, using a precise and well discretized voxel model of human head, which was incorporated a representative Glioblastoma Multiform tumor. The dosimetric results from MCNP5 code were exported to SISCODES program, which generated isodose curves representing absorbed dose rate in the brain. Isodose curves, neutron fluency, and dose components from BNCT and 252Cf brachytherapy are presented in this paper. (author)

  2. Relation between the CF2 radical and plasma density measured using LIF and cutoff probe in a CF4 inductively coupled plasma

    International Nuclear Information System (INIS)

    The behavior of the CF2 radical was studied in a CF4 inductively coupled plasma. The CF2 radical was measured using a laser-induced fluorescence method. Absolute electron density was measured using a cutoff probe and the electron temperature was measured using a double probe to study the relationship between these electron properties and the CF2 radical. To examine the relationship between them, the CF2 radical and electron density were measured as a function of the rf power, which is a major external parameter influencing the electron density. As the rf power was increased, the CF2 radical density increased in the range of low electron density, and then decreased beyond a critical electron density. The dependence of the CF2 radical density on the electron density was theoretically analyzed with rate equations. The theoretical result was in good agreement with experiment

  3. Forming trifluoromethylmetallates: competition between decarboxylation and C-F bond activation of group 11 trifluoroacetate complexes, [CF3CO2ML]-.

    Science.gov (United States)

    Rijs, Nicole J; O'Hair, Richard A J

    2012-03-28

    A combination of gas-phase 3D quadrupole ion trap mass spectrometry experiments and density functional theory (DFT) calculations have been used to examine the mechanism of thermal decomposition of fluorinated coinage metal carboxylates. The precursor anions, [CF(3)CO(2)MO(2)CCF(3)](-) (M = Cu, Ag and Au), were introduced into the gas-phase via electrospray ionization. Multistage mass spectrometry (MS(n)) experiments were conducted utilizing collision-induced dissociation, yielding a series of trifluoromethylated organometallic species and fluorides via the loss of CO(2), CF(2) or "CF(2)CO(2)". Carboxylate ligand loss was insignificant or absent in all cases. DFT calculations were carried out on a range of potentially competing fragmentation pathways for [CF(3)CO(2)MO(2)CCF(3)](-), [CF(3)CO(2)MCF(3)](-) and [CF(3)CO(2)MF](-). These shed light on possible products and mechanisms for loss of "CF(2)CO(2)", namely, concerted or step-wise loss of CO(2) and CF(2) and a CF(2)CO(2) lactone pathway. The lactone pathway was found to be higher in energy in all cases. In addition, the possibility of forming [CF(3)MCF(3)](-) and [CF(3)MF](-), via decarboxylation is discussed. For the first time the novel fluoride complexes [FMF](-), M = Cu, Ag and Au have been experimentally observed. Finally, the decomposition reactions of [CF(3)CO(2)ML](-) (where L = CF(3) and CF(3)CO(2)) and [CH(3)CO(2)ML](-) (where L = CH(3) and CH(3)CO(2)) are compared. PMID:22310991

  4. Atmospheric Chemistry of CF3CF=CH2: Reactions With Cl Atoms, OH Radicals and Ozone

    Science.gov (United States)

    Sulbaek Andersen, M. P.; Javadi, M. S.; Nielsen, O. J.; Hurley, M. D.; Wallington, T. J.; Singh, R.

    2006-12-01

    The detrimental effects of chlorine chemistry on stratospheric ozone levels are well established. Consequently, there has been a concerted international effort to find replacements for chlorofluorocarbons (CFCs) used previously as electronic equipment cleaners, heat transfer agents, refrigerants, and carrier fluids for lubricant deposition. The replacements for CFCs, hydrofluorocarbons (HFCs) and hydrofluorochlorocarbons (HCFCs), have found widespread industrial use over the past decade. Unsaturated fluorinated hydrocarbons are a new class of compounds which have been developed to replace CFCs and HFCs in air condition units. Prior to any large-scale industrial use an assessment of the atmospheric chemistry, and hence environmental impact, of these compounds is needed. To address this need the atmospheric chemistry of CF3CF=CH2 was investigated. Smog chamber/FTIR techniques were used to determine the following properties for this compound: (i) kinetics of reactions with chlorine atoms (ii) kinetics of reactions with hydroxyl radicals (iii) kinetics of reactions with ozone, (iv) atmospheric lifetimes, (v) atmospheric degradation mechanism, and (vi) global warming potentials. The results are discussed with regard to the environmental impact of CF3CF=CH2 and the atmospheric chemistry of unsaturated fluorinated hydrocarbons.

  5. An unambiguous signature in molecular frame photoelectron angular distributions of core hole localization in fluorine K-edge photoionization of CF4

    Science.gov (United States)

    McCurdy, C. W.; Rescigno, T. N.; Trevisan, C. S.; Lucchese, R. R.

    2016-05-01

    Molecular Frame Photoelectron Angular Distributions (MFPADs) are calculated using the Complex Kohn variational method for core-hole ionization of the carbon and fluorines in CF4 at photoelectron energies below 15 eV. The angular distributions for localized versus delocalized core-hole creation on the four equivalent fluorines are radically different. A strong propensity for the dissociation to take place via the mechanism hν +CF4 -->CF 4 + +e- -->CF 3 + +F(1s-1) -->CF 3 + +F+ + 2e- in which a core excited neutral fluorine atom ionizes during or after dissociation creates the conditions for experimental observation of core hole localization. Comparison with recent unpublished experiments at the Advanced Light Source that measured the Recoil Frame Photoelectron Angular Distributions (averaged over CF3 rotations around the recoil axis) for fluorine K-edge ionization gives unambiguous evidence that these experiments directly observed the creation of an almost completely localized core hole on the dissociating fluorine atom when the molecule was initially photoionized. Work supported by USDOE, OBES Chemical Sciences, Geosciences, and Biosciences Division.

  6. Absolute measurement of anti ν/sub p/ for 252Cf using the ORNL large liquid scintillator neutron detector

    International Nuclear Information System (INIS)

    The ORNL large liquid scintillator detector was used in a precise determination of anti ν/sub p/, the number of neutrons emitted promptly, for spontaneous fission of 252Cf. Measurements of the detector efficiency over a broad energy region were made by means of a proton-recoil technique employing the ORELA white neutron source. Monte Carlo calculation of the detector efficiency for a spectrum representative of 252Cf fission neutrons was calibrated with these elaborate measurements. The unusually flat response of the neutron detector resulted in elimination of several known sources of error. Experimental measurement was coupled with calculational methods to correct for other known errors. These measurements lead to an unusually small estimated uncertainty of 0.2% in the value obtained, anti ν/sub p/ = 3.773 +- 0.007

  7. Neutrons flux distribution in a 252Cf irradiation cell for neutron activation analysis

    International Nuclear Information System (INIS)

    A 100 microgram Californium-252 (252Cf) neutron source was embedded in a pure paraffin moderator surrounded by neutron and gamma ray shields to be used as an irradiation cell facility for NAA experiments. The cell is provided with a direct horizontal channel and a Vertical Tangential Irradiation Channel (VTIC) that are parallel to the source axis. The cadmium difference method was used in determining the thermal and epithermal neutron flux distributions along the axis of the (VTIC). For this purpose, 10 pairs of bare and cadmium covered pure gold foils were irradiated at the same positions along the axis of the (VTIC) in two separate runs. The absolute efficiency of the HPGe detector at the gamma ray energy 411.8 keV of 198 Au, was found to be 0.0318 ± 0.0025.The obtained distributions of thermal and epithermal neutron fluxes were tabulated and graphically presented. An evidence for contributions from 252Cf fission by epithermal neutrons was noticed. As an application on this facility the concentration of gold in an ore sample from gold - bearing ivory vein of wady Allaqui (at south west of eastern desert) was determined. It was found to be 612 ± 6 ppm

  8. Microscopic description of Cf-252 cold fission yields

    CERN Document Server

    Mirea, M; Sandulescu, A

    2009-01-01

    We investigate the cold fission of 252Cf within the two center shell model to compute the potential energy surface. The fission yields are estimated by using the semiclassical penetration approach. It turns out that the inner cold valley of the total potential energy is strongly connected with Z=50 magic number. The agreement with experimental values is very much improved only by considering mass and charge asymmetry degrees of freedom. Thus, indeed cold fission of 252Cf is a Sn-like radioactivity, related the other two "magic radioactivities", namely alpha-decay and heavy-cluster decay, called also Pb-like radioactivity. This calculation provides the necessary theoretical confidence to estimate the penetration cross section in producing superheavy nuclei, by using the inverse fusion process.

  9. Regeneration in cervix cancer after 252Cf neutron brachytherapy

    International Nuclear Information System (INIS)

    Regeneration of clonogens in human cervical cancer was assessed by the pathological evaluation of the hysterectomy specimen after intracavitary 252Cf neutron brachytherapy implants separated by varying time intervals followed by extrafascial hysterectomy. In this study, patients with bulky/barrel shaped Stage IB cervical cancers received 252Cf implants plus approximately 45 Gy of whole pelvis linear accelerator radiotherapy in approximately 25 fractions in 5 weeks followed by hysterectomy 4-6 weeks after radiotherapy. The specimens were studied grossly and microscopically for residual tumor. It was found that the fraction of positive specimens increased with elapsed time interval between implants. These findings support the hypothesis that there is repopulation of surviving clonogens with increased time interval between the implants. The observation also supports current concerns that rapid depopulation of tumor can lead to rapid repopulation, that is, rapid shrinkage of tumor can alter the physiological environment such that clonogens can rapidly regenerate

  10. Evaluation of mass distribution data from 252Cf spontaneous fission

    International Nuclear Information System (INIS)

    The mass distribution data of 252Cf spontaneous fission were evaluated based on 7 sets of available experimental data. The measured data were corrected for the standards and γ intensity used by using the new evaluated ones. The errors were made necessary adjusting. The evaluated experimental data were fitted with spline function without any restriction and with symmetric restriction. These two sets of fit data were recommended as reference data of the mass distribution of 252Cf spontaneous fission. The errors of the recommended data were considerably reduced comparing with the measured ones. The light and heavy peaks are not completely symmetric. Also there are fine structures on the right side of the light peak at A=109-111 and left side of the heavy peak at A=137-139. These should be paid attention and studied further. (author)

  11. Natural triploidy in Leporinus cf. elongatus bearing sex chromosomes

    Directory of Open Access Journals (Sweden)

    Wagner Franco Molina

    2007-01-01

    Full Text Available Although several cases of natural triploidy in fish have already been described, spontaneous polyploidy in species with differentiated sex chromosomes are rare. We report the occurrence of a triploid fish (3n = 81 Leporinus cf. elongatus, a species characterized by a highly differentiated ZZ/ZW sex chromosome system, from the São Francisco river. The occurrence of a ZZZ triploid adult indicates the viability of this chromosome constitution in this fish.

  12. Shielding of radiation fields generated by 252Cf in a concrete maze. Part 2 -- Simulation

    International Nuclear Information System (INIS)

    A streaming experiment performed in a concrete maze of shape and size typical of a radiotherapy room was simulated with the Monte Carlo program FLUKA. The purpose of the calculation was to test the performance of the code in the low energy neutron range, and at the same time to provide additional information which could help in optimizing shielding of medical facilities. Instrument responses were calculated at different maze locations for several experimental configurations and were compared with measurements. In addition, neutron and gamma fluence, ambient dose equivalent and effective dose were calculated at the same positions. Both sources used in the experiment, namely a bare 252Cf source and one shielded by a tungsten shell 5 cm thick, were considered in the simulation

  13. Time-Resolved Fourier Transform Emission Spectroscopy of CF3Br and CF3CFHCF3 in a Pulsed Electrical Discharge

    Czech Academy of Sciences Publication Activity Database

    Ferus, Martin; Civiš, Svatopluk; Kubelík, Petr; Nevrlý, V.; Bitala, P.; Grigorová, E.; Střižík, M.; Kubát, Pavel; Zelinger, Zdeněk

    2011-01-01

    Roč. 31, č. 3 (2011), s. 417-426. ISSN 0272-4324 R&D Projects: GA AV ČR IAA400400705; GA AV ČR IAAX00100903; GA MŠk OC09050; GA ČR(CZ) GAP108/11/1312 Institutional research plan: CEZ:AV0Z40400503 Keywords : helium discharge plasma * CF3Br * CF3CHFCF3 Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.602, year: 2011

  14. Absolute CF2 density and gas temperature measurements by absorption spectroscopy in dual-frequency capacitively coupled CF4/Ar plasmas

    International Nuclear Information System (INIS)

    Broadband ultraviolet absorption spectroscopy has been used to determine the CF2 radical density in dual-frequency capacitively coupled CF4/Ar plasmas, using the CF2 A~1B1←X~1A1 system of absorption spectrum. The rotational temperature of ground state CF2 and excited state CF was also estimated by using A~1B1←X~1A1 system and B2Δ−X2Π system, respectively. The translational gas temperature was deduced from the Doppler width of the Ar*(3P2) and Ar*(3P0) metastable atoms absorption line by using the tunable diode laser absorption spectroscopy. The rotational temperatures of the excited state CF are about 100 K higher than those of ground state CF2, and about 200 K higher than the translational gas temperatures. The dependences of the radical CF2 density, electron density, electron temperature, rotational temperature, and gas temperature on the high frequency power and pressure have been analyzed. Furthermore, the production and loss mechanisms of CF2 radical and the gas heating mechanisms have also been discussed

  15. Examination of the discharge mechanism of Li/CF(x) cells: Comparison of the electrochemical reduction mechanisms of PTFE and (CF(x))n by lithium

    Science.gov (United States)

    Baxam, Carl C.; Margalit, N.

    1991-01-01

    Swelling of (CF(x))(sub n) electrodes in commercial Li/(CF(x))(sub n) cells presents a limiting factor in cell design optimization. Examination of cathodes from such cells, after discharge, reveals a relation between cell operating temperatures and cathode swelling. Attempts to explain the swelling using the prevailing model for the cathode reaction have failed. A more suitable reaction mechanism is proposed based on the observed behavior of (CF(x))(sub n) electrodes on discharge and a comparison of the reaction products of (CF(x))(sub n) and polytetra fluoroethylene (PTFE) with lithium amalgams. The proposed mechanism is in agreement with the experimental data found in the literature.

  16. Boron enhancement of high LET brachy-therapy using Cf-252

    International Nuclear Information System (INIS)

    The authors have used a discrete ordinates one dimensional transport code to analyse the potential enhancement of high LET event size spectra and absorbed dose around a Cf-252 implant used for treatment of glioblastoma multiforme. Toxicity effectively limits the concentration of boron in malignant brain tissues to 13-60 μg/gm at the time of treatment. Event size spectra from Cf-252 in a tissue equivalent proportional counter were used to estimate the number of high LET events per rad as a function of event size. The dose enhancement for these conditions will vary with the distance from the sources because the thermal neutron fluence is more uniform than the fast neutron fluence throughout the irradiated volume. The fast neutron dose is enhanced by as much as 60% at 5 cm., while the RBE dose enhancement is roughly 30% at this point. The number of events depositing more than 100 kev in a cell nucleus, however, is increased by at least a factor of 20 at 5 cm. These conditions will increase the effectiveness of brain tumor implants for tissues near the periphery to the extent that effective treatment depends on such high LET events

  17. Am-Be Neutron Irradiator Used for Nuclear Instrumentation Training

    International Nuclear Information System (INIS)

    A neutron irradiator was assembled at IPEN (Nuclear and Energy Research Institute) facility to perform qualitative- quantitative analysis of materials, using thermal and fast neutrons. In order to determine the 116mIn decay constant, a thermal flux obtained experimentally by Monte Carlo N-Particle Transport Code-MCNP, in a previous work, was used in the nuclear experiment. The activity calculated from the activation parameters was 13.51±0.17 kBq and the activity determined experimentally was 12.51± 0.36 kBq. The decay constant determined by the pulse height analyzer (PHA) measures was 211.4 μ.s-1, and that determined by fitting the data using a Multichannel Scaler (MCS) system was 200.3 ± 1.6 μ.s-1. The half-life of 116mIn found in the literature is 3256.8 s, which corresponds to a decay constant of 212.8 μ.s-1. The present experiment does not intend to establish a new value for the decay constant: it solely aims students' practical exercises in nuclear properties of elements. This experiment is part of the nuclear experimental course. (authors)

  18. A Monte Carlo simulation and setup optimization of output efficiency to PGNAA thermal neutron using 252Cf neutrons

    Science.gov (United States)

    Zhang, Jin-Zhao; Tuo, Xian-Guo

    2014-07-01

    We present the design and optimization of a prompt γ-ray neutron activation analysis (PGNAA) thermal neutron output setup based on Monte Carlo simulations using MCNP5 computer code. In these simulations, the moderator materials, reflective materials, and structure of the PGNAA 252Cf neutrons of thermal neutron output setup are optimized. The simulation results reveal that the thin layer paraffin and the thick layer of heavy water moderating effect work best for the 252Cf neutron spectrum. Our new design shows a significantly improved performance of the thermal neutron flux and flux rate, that are increased by 3.02 times and 3.27 times, respectively, compared with the conventional neutron source design.

  19. PIXE, 252Cf-PDMS and radiochemistry applied for soil and vegetable analysis

    International Nuclear Information System (INIS)

    The aim of this work is to identify the elements present in vegetables and soils using PIXE (particle induced X-rays emission) and 252Cf-PDMS (252Cf plasma desorption mass spectrometry) techniques in order to estimate the possible influence of soil and agricultural techniques in the metal absorption by the vegetables. In this work, metal concentrations were evaluated in soil and vegetable samples from several regions, where different agricultural techniques were employed. Si, Zr, Ce, Th, Sc and Pb identified in the soil samples were not biologically available. Ga, Ge, As and Br identified in the tubercles indicate that spray pesticide used on the vegetable leaves was absorbed by them. 232Th and 238U present in the soil were not absorbed by the vegetables. The airborne particles from anthropogenic sources (as CFn, VCn) were absorbed by the vegetables. Compounds from mineral sources present in soil as V+, VCO3, HPO4, Cr+, CrOH+, Mn+, FeH+, Fe(OH)n and in the bioorganic compounds as N+, Ca(China)n+ and CnH+ were identified in vegetables. The metal absorption by the vegetables is not dependent of the metal concentration in soil. Different tubercles cultivated in the same soil show similar metal absorption. The exogenous contributions such as the elements present in water irrigation, pesticides, fertilizers and airborne particles deposited on leaves can be absorbed by vegetables. The absorption by the roots depends on the chemical compound of the elements. The use of pesticide sprays and air pollution can cause more contamination in the vegetables than in soil. The use of this methodology allows the identification of possible sources of metals in soils and in vegetables and the metal speciation

  20. Carrot fiber (CF) composite films for antioxidant preservation: Particle size effect.

    Science.gov (United States)

    Idrovo Encalada, Alondra M; Basanta, Maria F; Fissore, Eliana N; De'Nobili, Maria D; Rojas, Ana M

    2016-01-20

    The effect of particle size (53, 105 and 210 μm) of carrot fiber (CF) on their hydration properties and antioxidant capacity as well as on the performance of the CF-composite films developed with commercial low methoxyl pectin (LMP) was studied. It was determined that CF contained carotenoids and phenolics co-extracted with polysaccharides (80%), rich in pectins (15%). CF showed antioxidant activity and produced homogeneous calcium-LMP-based composites. The 53-μm-CF showed the lowest hydration capability and produced the least elastic and deformable composite film due probably to CF bridged by calcium-crosslinked LMP chains. Antioxidant activity associated to the loaded CF was found in composites. When L-(+)-ascorbic acid (AA) was also loaded, its hydrolytic stability increased with the decrease in CF-particle size, showing the lowest stability in the 0%-CF- and 210 μm-CF-LMP films. Below ≈ 250 μm, the particle size determined the hydration properties of pectin-containing CF, affecting the microstructure and water mobility in composites. PMID:26572445

  1. Nuclear charge distribution in the spontaneous fission of 252Cf

    OpenAIRE

    Wang, Taofeng; Zhu, Liping; WANG, LIMING; Men, Qinghua; Han, Hongyin; Xia, Haihong

    2015-01-01

    The measurement for charge distributions of fragments in 252Cf has been performed by using a unique style of detector setup consisting of a typical grid ionization chamber and a dE-E particle telescope. We found that the fragment mass dependency of the average width of the charge distribution shows a systematic decreased trend with the obvious odd-even effect. The variation of widths of charge distribution with kinetic energies shows an approximate V-shape curve due to the large number of neu...

  2. Leotia cf. lubrica forms arbutoid mycorrhiza with Comarostaphylis arbutoides (Ericaceae).

    Science.gov (United States)

    Kühdorf, Katja; Münzenberger, B; Begerow, D; Gómez-Laurito, J; Hüttl, R F

    2015-02-01

    Arbutoid mycorrhizal plants are commonly found as understory vegetation in forests worldwide where ectomycorrhiza-forming trees occur. Comarostaphylis arbutoides (Ericaceae) is a tropical woody plant and common in tropical Central America. This plant forms arbutoid mycorrhiza, whereas only associations with Leccinum monticola as well as Sebacina sp. are described so far. We collected arbutoid mycorrhizas of C. arbutoides from the Cerro de la Muerte (Cordillera de Talamanca), Costa Rica, where this plant species grows together with Quercus costaricensis. We provide here the first evidence of mycorrhizal status for the Ascomycete Leotia cf. lubrica (Helotiales) that was so far under discussion as saprophyte or mycorrhizal. This fungus formed arbutoid mycorrhiza with C. arbutoides. The morphotype was described morphologically and anatomically. Leotia cf. lubrica was identified using molecular methods, such as sequencing the internal-transcribed spacer (ITS) and the large subunit (LSU) ribosomal DNA regions, as well as phylogenetic analyses. Specific plant primers were used to confirm C. arbutoides as the host plant of the leotioid mycorrhiza. PMID:25033922

  3. Topological analysis of the CfA redshift survey

    Science.gov (United States)

    Vogeley, Michael S.; Park, Changbom; Geller, Margaret J.; Huchra, John P.; Gott, J. Richard, III

    1994-01-01

    We study the topology of large-scale structure in the Center for Astrophysics Redshift Survey, which now includes approximately 12,000 galaxies with limiting magnitude m(sub B) is less than or equal to 15.5. The dense sampling and large volume of this survey allow us to compute the topology on smoothing scales from 6 to 20/h Mpc; we thus examine the topology of structure in both 'nonlinear' and 'linear' regimes. On smoothing scales less than or equal to 10/h Mpc this sample has 3 times the number of resolution elements of samples examined in previous studies. Isodensity surface of the smoothed galaxy density field demonstrate that coherent high-density structures and large voids dominate the galaxy distribution. We compute the genus-threshold density relation for isodensity surfaces of the CfA survey. To quantify phase correlation in these data, we compare the CfA genus with the genus of realizations of Gaussian random fields with the power spectrum measured for the CfA survey. On scales less than or equal to 10/h Mpc the observed genus amplitude is smaller than random phase (96% confidence level). This decrement reflects the degree of phase coherence in the observed galaxy distribution. In other words the genus amplitude on these scales is not good measure of the power spectrum slope. On scales greater than 10/h Mpc, where the galaxy distribution is rougly in the 'linear' regime, the genus ampitude is consistent with the random phase amplitude. The shape of the genus curve reflects the strong coherence in the observed structure; the observed genus curve appears broader than random phase (94% confidence level for smoothing scales less than or equal to 10/h Mpc) because the topolgoy is spongelike over a very large range of density threshold. This departre from random phase consistent with a distribution like a filamentary net of 'walls with holes.' On smoothing scales approaching approximately 20/h Mpc the shape of the CfA genus curve is consistent with random phase

  4. Identification of neutrophil activation markers as novel surrogate markers of CF lung disease.

    Directory of Open Access Journals (Sweden)

    Timo Rath

    Full Text Available Cystic Fibrosis (CF lung disease is characterized by progressively declining lung function and represents a major factor contributing to the high morbidity and mortality associated with CF. However, apart from spirometry, respiratory disease surrogate markers reliably indicating CF lung disease and the occurrence of pulmonary exacerbations (PEx are still lacking. Within this study, we aimed to identify new experimental biomarkers for the detection of CF lung disease.54 adult and 26 pediatric CF patients were included in the study and serum concentrations of MMP-1, -2, -8, -9, -13, TIMP-1, TIMP-2, YKL-40, hyaluronic acid, procollagen III peptide were quantified by ELISA. CF lung disease was diagnosed by lung function test, PEx was defined based on a clinical scoring established by Rosenfeld in 2001.Adults and children with moderate to severe CF lung disease exhibited significantly increased serum expression of MMP-8, MMP-9, YKL-40 and TIMP-1. Further, MMP-8, MMP-9 and YKL-40 were significantly increased in adult CF patients suffering from PEx compared to those without clinical signs of respiratory exacerbation. MMP-8, MMP-9, YKL-40, and TIMP-1 serum levels were unaffected by the presence or absence of CF liver disease or pancreatic insufficiency.MMP-8, MMP-9, and YKL-40 might serve as novel non-invasive biomarkers of CF lung disease and PEx.

  5. Identification of Neutrophil Activation Markers as Novel Surrogate Markers of CF Lung Disease

    Science.gov (United States)

    Hage, Lisa; Kügler, Marion; Menendez, Katrin; Naehrlich, Lutz; Schulz, Richard; Roderfeld, Martin; Roeb, Elke

    2014-01-01

    Background and aims Cystic Fibrosis (CF) lung disease is characterized by progressively declining lung function and represents a major factor contributing to the high morbidity and mortality associated with CF. However, apart from spirometry, respiratory disease surrogate markers reliably indicating CF lung disease and the occurrence of pulmonary exacerbations (PEx) are still lacking. Within this study, we aimed to identify new experimental biomarkers for the detection of CF lung disease. Methods 54 adult and 26 pediatric CF patients were included in the study and serum concentrations of MMP-1, -2, -8, -9, -13, TIMP-1, TIMP-2, YKL-40, hyaluronic acid, procollagen III peptide were quantified by ELISA. CF lung disease was diagnosed by lung function test, PEx was defined based on a clinical scoring established by Rosenfeld in 2001. Results Adults and children with moderate to severe CF lung disease exhibited significantly increased serum expression of MMP-8, MMP-9, YKL-40 and TIMP-1. Further, MMP-8, MMP-9 and YKL-40 were significantly increased in adult CF patients suffering from PEx compared to those without clinical signs of respiratory exacerbation. MMP-8, MMP-9, YKL-40, and TIMP-1 serum levels were unaffected by the presence or absence of CF liver disease or pancreatic insufficiency. Conclusions MMP-8, MMP-9, and YKL-40 might serve as novel non-invasive biomarkers of CF lung disease and PEx. PMID:25545245

  6. Comparative study of electroless nickel film on different organic acids modified cuprammonium fabric (CF)

    Science.gov (United States)

    Zhao, Hang; Lu, Yinxiang

    2016-01-01

    Nickel films were grown on citric acid (CA), malic acid (MA) and oxalic acid (OA) modified cuprammonium fabric (CF) substrates via electroless nickel deposition. The nickel films were examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Their individual deposition rate and electromagnetic interference (EMI) shielding effectiveness (SE) were also investigated to compare the properties of electroless nickel films. SEM images illustrated that the nickel film on MA modified CF substrate was smooth and uniform, and the density of nickel nuclei was much higher. Compared with that of CA modified CF, the coverage of nickel nuclei on OA and MA modified CF substrate was very limited and the nickel particles size was too big. XRD analysis showed that the nickel films deposited on the different modified CF substrates had a structure with Ni (1 1 1) preferred orientation. All the nickel coatings via different acid modification were firmly adhered to the CF substrates, as demonstrated by an ultrasonic washing test. The result of tensile test indicated that the electroless nickel plating on CF has ability to strengthen the CF substrate while causes limited effect on tensile elongation. Moreover, the nickel film deposited on MA modified CF substrate showed more predominant in EMI SE than that deposited on CA or OA modified CF.

  7. Clustering and photochemistry of freon CF2Cl2 on argon and ice nanoparticles.

    Science.gov (United States)

    Poterya, Viktoriya; Kočišek, Jaroslav; Lengyel, Jozef; Svrčková, Pavla; Pysanenko, Andriy; Hollas, Daniel; Slavíček, Petr; Fárník, Michal

    2014-07-01

    The photochemistry of CF2Cl2 molecules deposited on argon and ice nanoparticles was investigated. The clusters were characterized via electron ionization mass spectrometry, and the photochemistry was revealed by the Cl fragment velocity map imaging after the CF2Cl2 photodissociation at 193 nm. The complex molecular beam experiment was complemented by ab initio calculations. The (CF2Cl2)n clusters were generated in a coexpansion with Ar buffer gas. The photodissociation of molecules in the (CF2Cl2)n clusters yields predominantly Cl fragments with zero kinetic energy: caging. The CF2Cl2 molecules deposited on large argon clusters in a pickup experiment are highly mobile and coagulate to form the (CF2Cl2)n clusters on ArN. The photodissociation of the CF2Cl2 molecules and clusters on ArN leads to the caging of the Cl fragment. On the other hand, the CF2Cl2 molecules adsorbed on the (H2O)N ice nanoparticles do not form clusters, and no Cl fragments are observed from their photodissociation. Since the CF2Cl2 molecule was clearly adsorbed on (H2O)N, the missing Cl signal is interpreted in terms of surface orientation, possibly via the so-called halogen bond and/or embedding of the CF2Cl2 molecule on the disordered surface of the ice nanoparticles. PMID:24911048

  8. Relations for the thermodynamic and transport properties in the testing environment of the Langley hypersonic CF4 tunnel

    Science.gov (United States)

    Sutton, K.

    1981-01-01

    Thermodynamic and transport properties of gaseous CF4 that can be used in flow field computer codes and theoretical analyses for comparison of results with experimental data from the Langley Hypersonic CF4 Tunnel are presented. The thermodynamic relations which are based on thermally perfect but calorifically imperfect gas are adequate for the testing environment of the CF4 tunnel and are simpler to use than the imperfect gas relations required to define the complete expansion from the tunnel reservoir. Relations for the transport properties are based on the kinetic theory of gases in which published experimental data are used in the derivation of the relations. Extensive experimental data were located for viscosity and the derived relation should provide values for viscosity with errors of less than 1 percent. The experimental data for thermal conductivity were limited with significant disagreement between the various sources. The derived relation will probably provide values for the thermal conductivity with errors of no more than 5 percent which is within the accuracy of the experimental data.

  9. Gas-chromatographic measurements of atmospheric CF2Cl2, CFCl3 and N2O in Antarctica

    Science.gov (United States)

    Hirota, H.; Makino, Y.; Chubachi, S.; Muramatsu, H.; Shiobara, M.

    1985-01-01

    Stratospheric ozone is produced photochemically and destroyed by reactions with such minor constituents as O, NOx, HOx, and ClOx. Chlorofluoromethanes (CF2Cl2 and CFCl3) and dinitrogen oxide (NwO) are considered as major sources of the stratospheric ClOx and NOx, respectively. It is well known that CF2Cl2 and CFCl3 are released only by man's activities, and are being accumulated in the troposphere. In order to assess the influence of these compounds on the natural ozone balance these gases have been measured over Japan since 1978. Measurements of Antarctic air samples are also indispensable to understanding the global distributions of these gases, because most CF2Cl2 and CFCl3 have been released in the Northern Hemisphere. Antarctic air samples were obtained by the 23rd, 24th and 25th Japanese Antarctic Research Expeditions, and analyzed by a gas-chromatographic method using an electron capture detector. Three experimental results were obtained: (1) latitudinal distribution of these gases from Tokyo to Syowa Station (69.0 deg S, 39.6 deg E), (2) time trends at Syowa Station, and (3) vertical distributions over Syowa Station. Results are reported.

  10. Absolute measurement of neutron source emission rate with manganese bath method

    International Nuclear Information System (INIS)

    The manganese bath method is one of the most widespread and exact method to measure neutron source emission rate (neutron source intensity) absolutely at present. Pouring some 56Mn solution with known activity into the bath, the system efficiency can be obtained from γ counts of 56Mn, which is measured by two NaI(Tl) detectors. From saturated counts of a 241Am-Be(α, n) neutron source in the bath, the source emission rate can be obtained. An standard 241Am-Be(α, n) source which is the transfer source of the CCRI(Ⅲ)-K9. AmBe international key comparison organized by the Comite Consultatif des Rayonnements Ionisants, was measured absolutely with the neutron source emission rate standard equipment (manganese bath method). The result is coincident with the average value of the comparison within the uncertainties, therefore the reliability of the standard equipment is verified. (authors)

  11. Role of excited CF3CFHO radicals in the atmospheric chemistry of HFC-134a

    DEFF Research Database (Denmark)

    Wallington, T.J.; Hurley, M.D.; Fracheboud, J.M.;

    1996-01-01

    Oz, CF3CFHO + O-2 --> CF3C(O)F + HO2, and decomposition via C-C bond scission, CF3CFHO + M --> CS3 + HC(O)F + M. CF3CFHO radicals were produced by two different reactions: either via the self-reaction of CF3CFHO2 radicals or via the CF3CFHO2 + NO reaction. It was found that decomposition was much...... more important when CF3CFHO radicals were produced via the CF3CFHO2 + NO reaction than when they were produced via the self-reaction of CF3CFHO2 radicals. We ascribe this observation to the formation of vibrationally excited CF3CFHO* radicals in the CF3CFHO2 + NO reaction. Rapid decomposition of CF3......The atmospheric degradation of HFC-134a (CF3CFH2) proceeds via the formation of CF3CFHO radicals, Long path length FTIR environmental chamber techniques were used to study the atmospheric fate of CF3CFHO radicals. Two competing reaction pathways were identified for CF3CFHO radicals: reaction with...

  12. Electron attachment line shapes, cross sections, and rate constants at ultralow energies in CF3SO3H, (CF3SO2)2O, and CF3I

    Science.gov (United States)

    Alajajian, S. H.; Man, K.-F.; Chutjian, A.

    1991-01-01

    Electron attachment cross sections are reported in the energy range 0-160 meV, and at resolutions of 6.0-6.5 meV (FWHM) for the molecules CF3SO3H (triflic acid), (CF3SO2)2O (triflic anhydride), and CF3I (methyl iodide). Use is made of the Kr photoionization method. Attachment line shapes are deconvoluted from the spectral slit (electron energy) function, and are converted to cross sections by normalization to thermal attachment rate constants at 300 K. Rate constants as a function of mean electron energy are calculated from the cross sections using a Maxwellian electron energy distribution function. Present data are compared with flowing-afterglow, Langmuir-probe results in triflic acid and anhydride, and with high-Rydberg ionization results in CF3I.

  13. Bk and Cf chromatographic separation and 249Bk/248Cm and 249Cf/248Cm elemental ratios determination by inductively coupled plasma quadrupole mass spectrometry

    International Nuclear Information System (INIS)

    The French Atomic Energy Commission has carried out several experiments for the study of minor-actinide transmutation processes in high intensity thermal neutron flux. In this context a Cm sample enriched in 248Cm (97%) was irradiated in a thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). The precise and accurate determination of Cf isotope ratios and of 249Bk/248Cm and 249Cf/248Cm elemental ratios in the 248Cm irradiated sample is crucial for the calculation of actinide neutron capture cross-sections.This work describes an analytical procedure for the separation and the isotope ratio measurement of Bk and Cf in the irradiated sample.The Bk and Cf separation is based on a lanthanides separation protocol previously developed by the laboratory. Well-defined retention times for Bk and Cf were obtained by coupling the Ionic Chromatography (IC) with an ICP-QMS. All conditions of element separation by IC and the different steps of the analytical protocol in order to obtain the isotopic and elemental ratios are presented. Relative uncertainties of Cf isotopic ratios range from 0.3% to 0.5% and the uncertainty of the 249Bk/248Cm and 249Cf/248Cm elemental ratios are respectively 6.1% and 3.2%.This level of uncertainty for both isotopic and elemental ratios is in perfect agreement with the requirement for transmutation studies. (authors)

  14. Assessment of the Microbial Constituents of the Home Environment of Individuals with Cystic Fibrosis (CF and Their Association with Lower Airways Infections.

    Directory of Open Access Journals (Sweden)

    Alya Heirali

    the home environment were not genetically related to those isolated from the lower airways of individuals with CF suggesting alternate sources of infection were more common, a few genetically related isolates were indeed identified. As such, the home environment may rarely serve as either the source of infection or a persistent reservoir for re-infection after clearance.

  15. Li^+ attachment mass spectrometric investigation of high-mass neutral species in the downstream region of Ar/CF4, Ar/CF4/O2 and Ar/CF4/H2 plasmas

    Science.gov (United States)

    Furuya, Kenji; Okumura, Hiroshi; Tamai, Yuji; Ide, Akihiro; Harata, Akira

    2008-10-01

    Recently gaseous high-mass species have received significant attentions as important contributors to the nucleation of films and particulates in fluorocarbon plasmas. We have unambiguously identified the gaseous high-mass neutral species in the downstream region of the Ar/CF4 plasma [1], using the Li^+ attachment ionization technique that is a fragment-free ionization method. In this report, we show the results of mass analysis of high-mass neutral species in the Ar/CF4/O2 and Ar/CF4/H2 plasmas as well as Ar/CF4. In the Ar/CF4 plasma, we observed CnF2n+2 (n = 2-7) and CnF2n (n = 4-8) as neutral species. Adding O2 to the Ar/CF4 plasma resulted in the intensity decrease of CnF2n+2 and CnF2n, especially of those with relatively small n values. CnF2nO (n = 1-7) were newly observed in the Ar/CF4/O2 plasma. In contrast, adding H2 to the Ar/CF4 plasma resulted in the production of various new compounds, such as CnF2n-2 (n=3-8), CnF2n-4 (n=3-9), CnF2n+1H (n=1-7), CnF2n-1H (n=2-8), CnF2n-3H (n=4-9) and CnF2n-5H (n=5-9). These species are produced through the abstraction of F from various CnFm species by the H radical and the addition of H to them. [1] K. Furuya, S. Yukita, H. Okumura, A. Harata, Chem. Lett. 34, 224 (2005).

  16. Diet of Physalaemus cf. cicada (Leptodactylidae) and Bufo granulosus (Bufonidae) in a semideciduous forest.

    Science.gov (United States)

    Santana, A S; Juncá, F A

    2007-02-01

    We determined the diet of the two most abundant anuran species which occur in the litter of a semideciduous forest (Lençóis, Bahia, Brazil), Physalaemus cf. cicada and Bufo granulosus in the dry and rainy seasons. Pitfall traps were used to collect anuran and invertebrate fauna, which showed the availability of prey in the environment. Physalaemus cf. cicada was present in both seasons and Bufo granulosus only in the rainy season. Both species fed mainly on Isoptera and Formicidae. However, there is a difference between the rainy and dry seasons concerning the diet of P. cf. cicada. During the rainy season P. cf. cicada consumed less Isoptera and more Formicidae than in the dry season. In the volumetric sense, Orthoptera was the most important alimentary category for P. cf. cicada and B. granulosus. The Jacobs electivity index indicated that Physalaemus cf. cicada and Bufo granulosus were specialists in Isoptera. PMID:17505759

  17. ESR study of the CF3xxxF radical in irradiated trifluoroacetamide single crystals

    International Nuclear Information System (INIS)

    ESR and deuteration studies of x-irradiated trifluroacetamide crystals at 77 0K show that the CF3(A) radical initially formed interacts with a fluorine nucleus on a neighboring molecule, resulting in an additional fluorine doublet of A/sub z/=10 G, A/sub y/0K and is irreversibly replaced by the ESR spectrum of CF3(B) that is stable to 200 0K. Based on an INDO calculation, the formation of CF3(A) occurs when the crystallographic intermolecular FxxxCF3 distance in the parent compound decreases from 3.77 to 2.4 A upon radical formation at 77 0K. Following the formation of CF3(A), the FxxxCF3 distance increases with time or temperature to approximately 3.0 A

  18. Shunt diode designs in Li/CF Shuttle batteries

    Science.gov (United States)

    Miller, D.; Higgins, R.

    1984-09-01

    Although Li/CF cells and batteries have an excellent safety record, they are included with other battery systems that require additional safety precautions. One precaution suggested is the inclusion of shunt diodes into these batteries. The benefits of this addition are examined. All cells tested at elevated temperatures vent regardless of length of time between being fully discharged and reversed or inclusion of the diode in the system. Cells discharged at ambient temperatures all show a relatively quick reversal, but stabilize at voltages that are high enough that the diodes are not functioning. Cells tested at depressed temperatures reverse the deepest of all cells tested, with the deepest reversal occurring very early in the test and voltages recovering to above -0.60 volts near the end of the tests. Anode limited cells will eliminate the venting during hot reversal.

  19. CF6-50 Short Core Exhaust Nozzle

    Science.gov (United States)

    Dusa, D. J.; Hrach, F. J.

    1980-01-01

    The General Electric CF6-50 engine nacelle was originally equipped with both fan nozzle and core nozzle thrust reversers. Many airline operators later deactivated the core reverser. Elimination of the core reverser enabled design changes to be made to help improve performance. A reduction in core nozzle length of approximately two feet was possible. This concept, defined as the Short Core Exhaust Nozzle, was evaluated in engine ground tests, including performance, acoustic, and endurance tests under the NASA/Lewis Engine Component Improvement Program. The test results verified the performance predictions from scale model tests. The Short Core Exhaust Nozzle provides an internal cruise SFC reduction of 0.9% without an increase in engine noise. The nozzle hardware successfully completed 1000 flight cycles of endurance testing with no signs of distress.

  20. Production of continuous intermingled CF/GF hybrid composite via fibre tow spreading technology

    OpenAIRE

    Diao, H.; Bismarck, A.; Robinson, P.; Wisnom, M. R.

    2014-01-01

    An air-assisted fibre tow spreader was used to produce continuous commingled glass and carbon fibre tows. Hybrid carbon and glass fibre (CF/GF) reinforced epoxy composites were manufactured from these commingled fibre tows by resin film infusion. The degree of hybridisation of the hybrid CF/GF tow was defined and characterised. Compared with the corresponding continuous CF/epoxy composite, the hybrid composite with a degree of hybridisation of 32.45% exhibits a more gradual tensile failure. T...

  1. Actinide production in 136Xe bombardments of 249Cf

    International Nuclear Information System (INIS)

    The production cross sections for the actinide products from 136Xe bombardments of 249Cf at energies 1.02, 1.09, and 1.16 times the Coulomb barrier were determined. Fractions of the individual actinide elements were chemically separated from recoil catcher foils. The production cross sections of the actinide products were determined by measuring the radiations emitted from the nuclides within the chemical fractions. The chemical separation techniques used in this work are described in detail, and a description of the data analysis procedure is included. The actinide production cross section distributions from these 136Xe + 249Cf bombardments are compared with the production cross section distributions from other heavy ion bombardments of actinide targets, with emphasis on the comparison with the 136Xe + 248Cm reaction. A technique for modeling the final actinide cross section distributions has been developed and is presented. In this model, the initial (before deexcitation) cross section distribution with respect to the separation energy of a dinuclear complex and with respect to the Z of the target-like fragment is given by an empirical procedure. It is then assumed that the N/Z equilibration in the dinuclear complex occurs by the transfer of neutrons between the two participants in the dinuclear complex. The neutrons and the excitation energy are statistically distributed between the two fragments using a simple Fermi gas level density formalism. The resulting target-like fragment initial cross section distribution with respect to Z, N, and excitation energy is then allowed to deexcite by emission of neutrons in competition with fission. The result is a final cross section distribution with respect to Z and N for the actinide products. 68 refs., 33 figs., 6 tabs

  2. Applicability of parallel plate avalanche counters to spontaneous fission from 252Cf

    International Nuclear Information System (INIS)

    The construction and performance of the parallel plate avalanche counters (PPACs) using a spontaneous fission source 252Cf is described in this paper. The parallel plate circular electrodes are made of aluminum foils having a thickness less than ten microns. After fabrication, the detectors and the source are mounted inside a reaction chamber, the source between the two detectors. A low pressure is created inside the chamber using isobutane (C4H10) and a high voltage is applied to the electrodes. The detectors are first operated at different pressures and voltages to find the optimum values of the pressure and the voltage. This is necessary to avoid the sparking threshold, to achieve a good time resolution and to keep the gain of the detectors high and constant. The PPACs are operated in 2π- and 4π-geometries. In 4π-geometry the detectors are allowed to function in coincidence and noncoincidence mode. The resulting pulse height and the time spectra are studied using the computer code ROOT and some conclusions are drawn from these analyses. The pulse height spectrum shows a clear separation between the fission fragments and the alpha particles and the time spectrum indicates a good intrinsic time resolution, 0.76 ns. (author)

  3. Detection of extragalactic CF+ toward PKS1830-211 -- Chemical differentiation in the absorbing gas

    CERN Document Server

    Muller, S; Black, J H; Amano, T

    2016-01-01

    We report the first extragalactic detection of CF+, the fluoromethylidynium ion, in the z=0.89 absorber toward PKS1830-211. We estimate an abundance of ~3E-10 relative to H2 and that ~1% of fluorine is captured in CF+. The absorption line profile of CF+ is found to be markedly different from that of other species observed within the same tuning, and is notably anti-correlated with CH3OH. On the other hand, the CF+ profile resembles that of [C I]. Our results are consistent with expected fluorine chemistry and point to chemical differentiation in the column of absorbing gas.

  4. Assessment of CF lung disease using motion corrected PROPELLER MRI: a comparison with CT

    Energy Technology Data Exchange (ETDEWEB)

    Ciet, Pierluigi [General Hospital Ca' Foncello, Radiology Department, Treviso (Italy); Sophia Children' s Hospital, Pediatric Pulmonology Erasmus MC, Rotterdam (Netherlands); Erasmus MC, Radiology, Rotterdam (Netherlands); Serra, Goffredo; Catalano, Carlo [University of Rome ' ' Sapienza' ' , Radiology, Rome (Italy); Bertolo, Silvia; Morana, Giovanni [General Hospital Ca' Foncello, Radiology Department, Treviso (Italy); Spronk, Sandra [Erasmus MC, Radiology, Rotterdam (Netherlands); Erasmus MC, Epidemiology, Rotterdam (Netherlands); Ros, Mirco [Ca' Foncello Hospital, Pediatrics, Treviso (Italy); Fraioli, Francesco [University College London (UCL), Institute of Nuclear Medicine, London (United Kingdom); Quattrucci, Serena [University of Rome Sapienza, Pediatrics, Rome (Italy); Assael, M.B. [Azienda Ospedaliera di Verona, Verona CF Center, Verona (Italy); Pomerri, Fabio [University of Padova, Department of Medicine-DIMED, Padova (Italy); Tiddens, Harm A.W.M. [Sophia Children' s Hospital, Pediatric Pulmonology Erasmus MC, Rotterdam (Netherlands); Erasmus MC, Radiology, Rotterdam (Netherlands)

    2016-03-15

    To date, PROPELLER MRI, a breathing-motion-insensitive technique, has not been assessed for cystic fibrosis (CF) lung disease. We compared this technique to CT for assessing CF lung disease in children and adults. Thirty-eight stable CF patients (median 21 years, range 6-51 years, 22 female) underwent MRI and CT on the same day. Study protocol included respiratory-triggered PROPELLER MRI and volumetric CT end-inspiratory and -expiratory acquisitions. Two observers scored the images using the CF-MRI and CF-CT systems. Scores were compared with intra-class correlation coefficient (ICC) and Bland-Altman plots. The sensitivity and specificity of MRI versus CT were calculated. MRI sensitivity for detecting severe CF bronchiectasis was 0.33 (CI 0.09-0.57), while specificity was 100 % (CI 0.88-1). ICCs for bronchiectasis and trapped air were as follows: MRI-bronchiectasis (0.79); CT-bronchiectasis (0.85); MRI-trapped air (0.51); CT-trapped air (0.87). Bland-Altman plots showed an MRI tendency to overestimate the severity of bronchiectasis in mild CF disease and underestimate bronchiectasis in severe disease. Motion correction in PROPELLER MRI does not improve assessment of CF lung disease compared to CT. However, the good inter- and intra-observer agreement and the high specificity suggest that MRI might play a role in the short-term follow-up of CF lung disease (i.e. pulmonary exacerbations). (orig.)

  5. Assessment of CF lung disease using motion corrected PROPELLER MRI: a comparison with CT

    International Nuclear Information System (INIS)

    To date, PROPELLER MRI, a breathing-motion-insensitive technique, has not been assessed for cystic fibrosis (CF) lung disease. We compared this technique to CT for assessing CF lung disease in children and adults. Thirty-eight stable CF patients (median 21 years, range 6-51 years, 22 female) underwent MRI and CT on the same day. Study protocol included respiratory-triggered PROPELLER MRI and volumetric CT end-inspiratory and -expiratory acquisitions. Two observers scored the images using the CF-MRI and CF-CT systems. Scores were compared with intra-class correlation coefficient (ICC) and Bland-Altman plots. The sensitivity and specificity of MRI versus CT were calculated. MRI sensitivity for detecting severe CF bronchiectasis was 0.33 (CI 0.09-0.57), while specificity was 100 % (CI 0.88-1). ICCs for bronchiectasis and trapped air were as follows: MRI-bronchiectasis (0.79); CT-bronchiectasis (0.85); MRI-trapped air (0.51); CT-trapped air (0.87). Bland-Altman plots showed an MRI tendency to overestimate the severity of bronchiectasis in mild CF disease and underestimate bronchiectasis in severe disease. Motion correction in PROPELLER MRI does not improve assessment of CF lung disease compared to CT. However, the good inter- and intra-observer agreement and the high specificity suggest that MRI might play a role in the short-term follow-up of CF lung disease (i.e. pulmonary exacerbations). (orig.)

  6. Isotopic yield in cold binary fission of even-even 244-258Cf isotopes

    Science.gov (United States)

    Santhosh, K. P.; Cyriac, Annu; Krishnan, Sreejith

    2016-05-01

    The cold binary fission of even-even 244-258Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that for 244,246,248Cf isotopes highest yield is for the fragments with isotope of Pb (Z = 82) as one fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the fragments with isotope of Hg (Z = 80) as one fragment. In the case of 254,256,258Cf isotopes the highest yield is for the fragments with Sn (Z = 50) as one fragment. Thus, the fragment combinations with maximum yield reveal the role of doubly magic and near doubly magic nuclei in binary fission. It is found that asymmetric splitting is favored for Cf isotopes with mass number A ≤ 250 and symmetric splitting is favored for Cf isotopes with A > 252. In the case of Cf isotope with A = 252, there is an equal probability for asymmetric and symmetric splitting. The individual yields obtained for the cold fission of 252Cf isotope are compared with the experimental data taken from the γ- γ- γ coincidences technique using Gammasphere.

  7. Detection of ternary fission fragments from 252Cf with a position-sensitive ΔE-E telescope

    International Nuclear Information System (INIS)

    Using a thin silicon diode detector with thickness of 12 μm coupled with a Timepix detector (equipped with a 300 μm silicon sensor), a position-sensitive ΔE-E telescope has been constructed. The telescope provides information about position, energy, time and type of registered particles. The emission probabilities and the energy distribution of ternary particles (He, Li, Be) from 252Cf spontaneous fission source were determined using a pair of these telescopes operated in coincidence and with synchronized readout. The response of Timepix detector to different particle species was tested by ternary particles

  8. Design of a 252Cf neutron assay system for evaluation at the Savannah River Plant fuel fabrication facility

    International Nuclear Information System (INIS)

    A nondestructive assay (NDA) unit will be evaluated at the Savannah River Plant (SRP) reactor fuel fabrication facility for measurement of a range of highly enriched uranium materials. The unit employs cyclic neutron interrogation with a Cf-252 neutron source followed by delayed-neutron counting to assay the U-235 content of fuel alloys with up to 2.4 kg U-235 per item in addition to scrap and waste with a lower U-235 content. The accuracy goal for the majority of the measurements is 1 to 3 percent

  9. SF6 ground-based infrared solar absorption measurements: long-term trend, pollution events, and a search for SF5CF3 absorption

    International Nuclear Information System (INIS)

    Infrared solar spectra recorded with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak (31.9 deg. N latitude, 111.6 deg. W, 2.09 km altitude), southwest of Tucson, Arizona, have been analyzed to retrieve average SF6 tropospheric mixing ratios over a two-decade time span. The analysis is based primarily on spectral fits to absorption by the intense, unresolved ν3 band Q branch at 947.9 cm-1. A best fit to measurements recorded with SF6 near typical background concentrations yields a SF6 increase in the average tropospheric mixing ratio from 1.13 pptv (10-12 per unit volume) in March 1982 to 3.77 pptv in March 2002. The long-term increase by a factor of 3.34 over the time span is consistent with the rapid growth of surface mixing ratios measured in situ at Northern Hemisphere remote stations, though the infrared measurements show a large scatter. Average tropospheric mixing ratio enhancements above background by 2-3 orders of magnitude have been identified in spectra recorded on 5 days between November 1988 and April 1997. These spectra were individually analyzed in an attempt to detect the strongest 8-12 μm band of SF5CF3, a molecule recently identified with an atmospheric growth that has closely paralleled the rise in SF6 during the past three decades. Absorption by the strongest SF5CF3 band was predicted to be above the noise level in the Kitt Peak spectrum with the highest average mean tropospheric SF6 mixing ratio, assuming the reported atmospheric SF5CF3/SF6 ratio and a room temperature absorption cross sections reported for the SF5CF3 903-cm-1 band. An upper limit of 8x1015 molecules cm-2 for the SF5CF3 total column was estimated for this case. We hypothesize that the highly elevated SF6 levels above Kitt Peak resulted from a local release experiment rather than production via electrochemical fluoridation of intermediate products, the proposed source of atmospheric SF5CF3. The absence of the SF5CF3 feature in the spectra

  10. Molecular spectroscopy beyond the born-oppenheimer approximation: a computational study of the CF(3)O and CF(3)S radicals.

    Science.gov (United States)

    Marenich, Aleksandr V; Boggs, James E

    2007-11-01

    This paper addresses some advances in the theoretical description of molecular spectroscopy beyond the Born-Oppenheimer adiabatic approximation. A solution of the nuclear dynamics problem complicated by the EE Jahn-Teller effect and spin-orbit coupling is considered for the case of the CF3O and CF3S radicals, all the model parameters being obtained solely from ab initio calculations without any adjustment to experimental numbers. Vibrational and vibronic model parameters were calculated at the equation-of-motion coupled cluster level of theory with basis sets of triple-zeta quality. The spin-orbit coupling in X 2E CF3O and CF3S was parametrized by means of a perturbative solution of the full Breit-Pauli spin-orbit operator. Spin-vibronic eigenvalues and eigenfunctions were computed in a basis set of products of electronic, electron spin, and vibrational functions. Results demonstrate the importance of explicit inclusion of the spin-orbit coupling and at least cubic Jahn-Teller terms in the model Hamiltonian for the high precision evaluation of spin-vibronic energy levels of CF3O and CF3S. The theoretical results support and complement the spectroscopic data observed for these species. PMID:17469808

  11. Comparison of DD, DT and Cf-252 neutron excitation of light and medium mass nuclei for field PGNAA applications

    Energy Technology Data Exchange (ETDEWEB)

    Seabury, E.H. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States)]. E-mail: Edward.Seabury@inl.gov; Blackburn, B.W. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States); Chichester, D.L. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States); Wharton, C.J. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States); Caffrey, A.J. [Idaho National Laboratory, P.O. Box 1625 Idaho Falls, ID 8341-3840 (United States)

    2007-08-15

    Prompt Gamma Ray Neutron activation analysis can offer significant cost and safety advantages in the identification of explosives and toxic chemicals. As an example, the US military examined over a thousand suspect chemical munitions with Idaho National Laboratory's PINS Chemical Assay System last year. PGNAA requires, of course, a neutron source to excite the atomic nuclei of the item under test via neutron capture and inelastic neutron scattering reactions and the choice of neutron source can drastically affect PGNAA system performance. We have carried out Monte Carlo and laboratory experiments comparing DD, DT and Cf-252 neutrons incident on light and medium mass chemical elements, toward optimizing the design of future neutron-generator-based PGNAA systems for field use. We report the excitation of (n, {gamma}) and (n, n') gamma rays from these elements by each type of neutron source.

  12. Comparison of DD, DT and Cf-252 neutron excitation of light and medium mass nuclei for field PGNAA applications

    International Nuclear Information System (INIS)

    Prompt Gamma Ray Neutron activation analysis can offer significant cost and safety advantages in the identification of explosives and toxic chemicals. As an example, the US military examined over a thousand suspect chemical munitions with Idaho National Laboratory's PINS Chemical Assay System last year. PGNAA requires, of course, a neutron source to excite the atomic nuclei of the item under test via neutron capture and inelastic neutron scattering reactions and the choice of neutron source can drastically affect PGNAA system performance. We have carried out Monte Carlo and laboratory experiments comparing DD, DT and Cf-252 neutrons incident on light and medium mass chemical elements, toward optimizing the design of future neutron-generator-based PGNAA systems for field use. We report the excitation of (n, γ) and (n, n') gamma rays from these elements by each type of neutron source

  13. Comparison of DD, DT and Cf-252 neutron excitation of light and medium mass nuclei for field PGNAA applications

    Science.gov (United States)

    Seabury, E. H.; Blackburn, B. W.; Chichester, D. L.; Wharton, C. J.; Caffrey, A. J.

    2007-08-01

    Prompt Gamma Ray Neutron activation analysis can offer significant cost and safety advantages in the identification of explosives and toxic chemicals. As an example, the US military examined over a thousand suspect chemical munitions with Idaho National Laboratory's PINS Chemical Assay System last year. PGNAA requires, of course, a neutron source to excite the atomic nuclei of the item under test via neutron capture and inelastic neutron scattering reactions and the choice of neutron source can drastically affect PGNAA system performance. We have carried out Monte Carlo and laboratory experiments comparing DD, DT and Cf-252 neutrons incident on light and medium mass chemical elements, toward optimizing the design of future neutron-generator-based PGNAA systems for field use. We report the excitation of (n, γ) and (n, n‧) gamma rays from these elements by each type of neutron source.

  14. PRAGMA-CF. A quantitative structural lung disease CT outcome in young children with cystic fibrosis

    DEFF Research Database (Denmark)

    Rosenow, Tim; Oudraad, Merel C.J.; Murray, Conor P.;

    2015-01-01

    RATIONALE: Chest computed tomography (CT) is the gold standard for demonstrating cystic fibrosis (CF) airways disease. However, there are no standardised outcome measures appropriate for children under 6 years. OBJECTIVES: We developed the Perth-Rotterdam Annotated Grid Morphometric Analysis for CF...

  15. The nonhospital costs of care of patients with CF in The Netherlands : Results of a questionnaire

    NARCIS (Netherlands)

    Wildhagen, MF; Verheij, JBGM; Verzijl, JG; Gerritsen, J; Bakker, W; Hilderink, HBM; tenKate, LP; Tijmstra, T; Kooij, L; Habbema, JDF

    1996-01-01

    Cystic fibrosis (CF) causes a relatively high medical consumption, A large part of the treatment takes place at home, Because data regarding nonhospital care are lacking, we wished to determine the costs of care of patients with CF outside the hospital. A questionnaire was sent to 73 patients with C

  16. Evidence for crustal degassing of CF4 and SF6 in Mojave Desert groundwaters

    Science.gov (United States)

    Deeds, D.A.; Vollmer, M.K.; Kulongoski, J.T.; Miller, B.R.; Muhle, J.; Harth, C.M.; Izbicki, J.A.; Hilton, David R.; Weiss, R.F.

    2008-01-01

    Dissolved tetrafluoromethane (CF4) and sulfur hexafluoride (SF6) concentrations were measured in groundwater samples from the Eastern Morongo Basin (EMB) and Mojave River Basin (MRB) located in the southern Mojave Desert, California. Both CF4 and SF6 are supersaturated with respect to equilibrium with the preindustrial atmosphere at the recharge temperatures and elevations of the Mojave Desert. These observations provide the first in situ evidence for a flux of CF4 from the lithosphere. A gradual basin-wide enhancement in dissolved CF4 and SF6 concentrations with groundwater age is consistent with release of these gases during weathering of the surrounding granitic alluvium. Dissolved CF4 and SF6 concentrations in these groundwaters also contain a deeper crustal component associated with a lithospheric flux entering the EMB and MRB through the underlying basement. The crustal flux of CF4, but not of SF6, is enhanced in the vicinity of local active fault systems due to release of crustal fluids during episodic fracture events driven by local tectonic activity. When fluxes of CF4 and SF6 into Mojave Desert groundwaters are extrapolated to the global scale they are consistent, within large uncertainties, with the fluxes required to sustain the preindustrial atmospheric abundances of CF4 and SF6. ?? 2007 Elsevier Ltd. All rights reserved.

  17. Improved Cryptosporidium parvum oocysts propagation using dexamethasone suppressed CF-1 mice

    Science.gov (United States)

    This study evaluates Cryptosporidium parvum oocyst production in dexamethasone suppressed CF-1 and C57BL/6 mice. Both models can yield 1 x 109 total oocysts over a 20 day production period; however, only 20 CF-1 mice are required to reliably achieve this goal compared...

  18. Decoupling of uranium metal with borated plaster using 252Cf nose analysis methods

    International Nuclear Information System (INIS)

    The use of borated plaster to isolate uranium (93.2 wt % 235U) metal was studied in a series of subcritical experiments with uranium metal cylinders (7.0 in. diam, 2.0 in. thick) and slabs (approx.1.4 x approx.5.4 x approx.10.1 in. dimensions). In the cylindrical experiments, the thickness of borated plaster was varied up to 10 in. and the subcriticality measured using the 252Cf-source-driven neutron noise analysis method. In the experiments with the uranium slabs, an array of slabs 3 wide and 8 high was assembled in steps to demonstrate the subcriticality of this array with 3.75-in.-thick borated plaster as an isolating material between all uranium slabs. In the slab experiments, both noise analysis and source neutron multiplication measurements were performed. Before assembly of the slab array the presence of boron in the plaster was verified by neutron transmission and gamma-ray spectrometry measurements

  19. Fabrication of Al2O3/glass/Cf Composite Substrate with High Thermal Conductivity

    Science.gov (United States)

    Wang, S. X.; Liu, G. S.; Ouyang, X. Q.; Wang, Y. D.; Zhang, D.

    2016-02-01

    In this paper, carbon fiber with high thermal conductivity was introduced into the alumina-based composites. To avoid oriented alignment of carbon fibers (Cf) and carbothermal reactions during the sintering process, the Al2O3/glass/Cf substrate was hot-pressed under a segmental-pressure procedure at 1123 K. Experimental results show that carbon fibers randomly distribute and form a bridging structure in the matrix. The three-dimensional network of Cf in Al2O3/glass/Cf substrate brings excellent heat conducting performance due to the heat conduction by electrons. The thermal conductivity of Al2O3/30%glass/30%Cf is as high as 28.98 W mK-1, which is 4.56 times larger than that of Al2O3/30%glass.

  20. Pressure and temperature induced elastic properties of Am and Cf monobismuthides

    Science.gov (United States)

    Jain, S.; Shriya, S.; Khenata, R.; Varshney, M.; Varshney, Dinesh

    2016-05-01

    The pressure and temperature dependent mechanical properties as melting temperature, hardness and brittle nature of XBi (X = Am and Cf) are studied. The rare earth actinides pnictides showed a structural phase transition (B1-B2) at a transition pressure (PT) of 14.3GPa (AmBi) and 10.8GPa (CfBi). Pressure dependence of melting temperature (Tm) discerns an increase inferring the hardening or stiffening of the lattice as a consequence of bond compression and bond strengthening. Suppressed TM as functions of temperature infers the weakening of the lattice results in bond weakening in XBi (X = Am, Cf). Vickers Hardness (HV), Poisson's and Pugh ratio of XBi (X = Am and Cf) demonstrates that XBi (X = Am and Cf) is mechanically stiffened, thermally softened and brittle on applied pressure and temperature.

  1. Fracture toughness of CF8 castings at four kelvin

    International Nuclear Information System (INIS)

    The first fracture toughness measurements for CF8 stainless steel castings in liquid helium at 4 K are reported. Single-phase (austenite) and duplex (austenite + delta-ferrite) castings were tested. On the basis of estimates from J-integral data, the plane-strain fracture toughness (K /SUB lc/ ) of castings containing 3.2 to 14.5 pct delta-ferrite ranged from 84 to 179 MPa X m /SUP 1/2/ at 4 K. In contrast, a fully austenitic casting (0 pct delta-ferrite) exhibited a K /SUB lc/ value of 331 MPa X m /SUP 1/2/ , which is nearly equivalent to the toughness of a wrought AISI 304 stainless steel of a similar strength. Light and scanning electron microscop studies indicate that the inferior toughness of castings containing delta-ferrite may be attributed to the brittleness of this body-centered-cubic phase at cryogenic temperatures and its distribution in th microstructure. The relative stability of the austenitic phase with respect to martensitic phase transformation may also play a significant role

  2. Prompt Neutron Emission in 252CF Spontaneous Fission

    Science.gov (United States)

    Hambsch, F.-J.; Oberstedt, S.; Zeynalov, Sh.

    2011-10-01

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results from digital data acquisition and digital signal processing analysis with results of the pioneering work of Budtz-Jørgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213-equivalent neutron detector in total about 107 fission fragment-neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution, neutron time-of-flight and pulse shape have been investigated using a 12 bit waveform digitizer. The signal waveforms have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of emitted neutrons as a function of total kinetic energy (TKE) of the fragments is in very good agreement with theoretical calculations in the range of TKE from 140-220 MeV.

  3. Neutron emission in fission of 252Cf(sf)

    Science.gov (United States)

    Zeynalov, Sh.; Hambsch, F.-J.; Oberstedt, S.; Fabry, I.

    2009-10-01

    The prompt neutron emission in spontaneous fission of 252Cf has been investigated applying digital signal electronics. The goal was to compare the results of this digital data acquisition and digital signal processing analysis to the results of the pioneering work of Budtz-Jo/rgensen and Knitter. Using a twin Frisch-grid ionization chamber for fission fragment (FF) detection and a NE213 equivalent neutron detector in total about 10 neutron coincidences have been registered. Fission fragment kinetic energy, mass and angular distribution have been investigated using a 10 bit waveform digitizer. Neutron time- of- flight and pulse shape have been measured using analogue CAMAC modules, a 1 ns TDC and a pair of 12 bit charge-to-digital-converters. The fission fragment signals have been analyzed using digital signal processing algorithms. The results are in very good agreement with literature. For the first time the dependence of the number of neutrons as a function of total kinetic energy (TKE) of the fragments does not drop at low TKE.

  4. Nuclear charge distribution in the spontaneous fission of 252Cf

    CERN Document Server

    Wang, Taofeng; Wang, Liming; Men, Qinghua; Han, Hongyin; Xia, Haihong

    2015-01-01

    The measurement for charge distributions of fragments in 252Cf has been performed by using a unique style of detector setup consisting of a typical grid ionization chamber and a dE-E particle telescope. We found that the fragment mass dependency of the average width of the charge distribution shows a systematic decreased trend with the obvious odd-even effect. The variation of widths of charge distribution with kinetic energies shows an approximate V-shape curve due to the large number of neutron emission for the high excitation energies and cold fragmentation with low excitation energies. As for the behavior of the average nuclear charge with respect to its deviation {\\Delta}Z from the unchanged charge distribution (UCD) as a function of the mass number of primary fragments A*, for asymmetric fission products {\\Delta}Z is negative value, while upon approaching mass symmetry {\\Delta}Z turns positive. Concerning the energy dependence of the most probable charge for given primary mass number A*, the obvious inc...

  5. Project 252Cf-D2O. The multisphere system of neutron dosimetry and spectrometry (M.S.-N.D.S.). Studies of applications to health physics

    International Nuclear Information System (INIS)

    The project 252Cf-D2O is articulated upon the utilization of a 200μg nominal 252Cf spontaneous neutron fission source, used bare and under D2O spherical moderators, giving leakage neutron spectra experimentally known and/or calculated. This project has for objective the applications of those sources to Health Physics, in dosimetry (calibration of ''rad'' and ''rem-meters'') and in spectrometry, associated with the experimental system of measurements made by the generalization of the BONNER Spheres, known as ''the Multisphere System''. This communication describes the normalization method used and the results obtained leading to the adoption of a reference matrix called ''the Log-Normal Multisphere Matrix'' (LN-MM) giving the energies response functions of the generalized system for all the spheres diameters between 40 and 400 millimeters and for all the energies between 0.4eV and 15MeV

  6. Potential groundwater age tracer found: Halon-1301 (CF3Br), as previously identified as CFC-13 (CF3Cl)

    Science.gov (United States)

    Beyer, Monique; van der Raaij, Rob; Morgenstern, Uwe; Jackson, Bethanna

    2014-09-01

    Groundwater dating using anthropogenic and natural tracer substances is a powerful tool for understanding groundwater dynamics for improved management of groundwater resources. Due to limitations in individual dating methods, often multiple tracers are used to reduce ambiguities. It is commonly accepted that there is a need for further complementary age tracers, in addition to current ones (e.g., tritium, SF6, and CFCs). We propose a potential new groundwater age tracer, Halon-1301 (CF3Br), which can easily be determined using gas chromatography with an attached electron capture detector (GC/ECD) developed by Busenberg and Plummer (2008). Its peak was noted by Busenberg and Plummer (2008), but they believed it to be CFC-13 (CF3Cl) at that time. We performed rigorous tests on gases containing or excluding Halon-1301 and CFC-13 and modern water samples and concluded that the two compounds have extremely similar retention times. Additionally, we found that the ECD response of CFC-13 is far too low to be detected in groundwater or air using standard volumes and sampling techniques. However, the peak areas and concentrations Busenberg and Plummer (2008) reported are in line with what would be expected for Halon-1301. Thus, we are confident that the peak formerly identified as CFC-13 is actually Halon-1301. Busenberg agrees with our findings. We further suggest that Halon-1301 has potential as a (complementary) age tracer, due to its established atmospheric history, and could hypothetically be used to date groundwater recharged in the 1970s or onward. We discuss known relevant properties, such as solubility and stability of Halon-1301 in the context of how these effect its potential application as a groundwater age tracer. Some open questions remain concerning how conservative Halon-1301 is—is it subject to degradation, retardation, and/or local contamination in groundwater. We are confident that Halon-1301 possesses important tracer relevant properties, but further

  7. A comparison of {sup 252}Cf and 14-MeV neutron excitation to identify chemical warfare agents by PGNAA

    Energy Technology Data Exchange (ETDEWEB)

    Caffrey, A.J.; Harlow, B.D.; Edwards, A.J.; Krebs, K.M.; Jones, J.L.; Yoon, W.; Zabriskie, J.M.; Dougan, A.D.

    2000-07-01

    Since 1992, Idaho National Engineering and Environmental Laboratory's portable isotopic neutron spectrometry (PINS) system has been widely used for the nondestructive assessment of munitions suspected to contain chemical warfare agents, such as the nerve agent sarin. PINS is a {sup 252}Cf-based prompt gamma-ray neutron activation analysis (PGNAA) system. The standard PINS system employs a partially moderated 5-{micro}g {sup 252}Cf source emitting 10{sup 7} n/s to excite the atomic nuclei inside the item under test. The chemical elements inside the item are revealed by their characteristic gamma-ray spectrum, measured by a high-resolution high-purity germanium gamma-ray spectrometer. The system computer then infers the fill compound or mixture from the elemental data extracted from the gamma-ray spectrum. Reliable PINS assessments can be completed in as little as 100 s for favorable cases such as white phosphorus smoke munitions, but normally, a 1000 to 3000 live-second counting interval is required. To improve PINS throughput when hundreds or more munitions must be assessed, they are evaluating the possible advantages of 14-MeV neutron excitation over their current radioisotopic source.

  8. Adenoviral gene transfer corrects the ion transport defect in the sinus epithelia of a porcine CF model.

    Science.gov (United States)

    Potash, Andrea E; Wallen, Tanner J; Karp, Philip H; Ernst, Sarah; Moninger, Thomas O; Gansemer, Nicholas D; Stoltz, David A; Zabner, Joseph; Chang, Eugene H

    2013-05-01

    Cystic fibrosis (CF) pigs spontaneously develop sinus and lung disease resembling human CF. The CF pig presents a unique opportunity to use gene transfer to test hypotheses to further understand the pathogenesis of CF sinus disease. In this study, we investigated the ion transport defect in the CF sinus and found that CF porcine sinus epithelia lack cyclic AMP (cAMP)-stimulated anion transport. We asked whether we could restore CF transmembrane conductance regulator gene (CFTR) current in the porcine CF sinus epithelia by gene transfer. We quantified CFTR transduction using an adenovirus expressing CFTR and green fluorescent protein (GFP). We found that as little as 7% of transduced cells restored 6% of CFTR current with 17-28% of transduced cells increasing CFTR current to 50% of non-CF levels. We also found that we could overcorrect cAMP-mediated current in non-CF epithelia. Our findings indicate that CF porcine sinus epithelia lack anion transport, and a relatively small number of cells expressing CFTR are required to rescue the ion transport phenotype. These studies support the use of the CF pig as a preclinical model for future gene therapy trials in CF sinusitis. PMID:23511247

  9. Effects of G2102 for life prolongation of the mouse irradiated by neutron (Cf252 source)

    International Nuclear Information System (INIS)

    5 mrem/hr of neutron-dose was irradiated for 3 minutes in every two days to the mouse fed with alkaloid component of ginseng (G2102). The results are as follows: 1) LD50 of mouse (ICR species) is 3.75 mrem and the mouse survived more than 30 days with the neutron-dose of 0.25 mrem/days. 2) When the cancer-mouse was treated with neutron and G2102 together the life was increased by 221%. 3) The mouse which fed with G2102 for 35 days before neutron was irradiated with the dose of 4 mrem, were survived 100%. 4) By feeding G2102 for 20-35 days before the neutron irradiation, the serum γ-globulin and albumin were recovered 100%. 5) It is assumed that α-lipoprotein was decreased and chylomicron was increased by the neutron irradiation since the neutron inactivated the LPL (lipoprotein lipase). 6) Treatment of G2102 seems to be effective on the recovery of lymphocytes, however, it do not seem to be effective on the neutrophills in 30 days. (author)

  10. Nitrogen source for uptake by Gyrodinium cf. aureolum in a tidal front

    Digital Repository Service at National Institute of Oceanography (India)

    LeCorre, P.; L'Helguen, S.; Wafar, M.V.M.

    Notes Chl a (pg liter-‘) 0 Sl 0 D(!%H 10 20 30 tog,, ( Cell numbers) 5 7 Fig. 3. Profiles of inorganic N nutrients, PON, Chl a, and cell counts at M2 (well-mixed waters) and Sl (stratified waters). V.G. micromass MM601 isotope mass spec...- ever, lacking, and direct observations in en- closure experiments (Brockmann et al. 1985) did not show migration of G. aureolum cells to nutrient-sufficient lower layers even when the upper layers became nutrient exhausted. Periodic development...

  11. Computer analysis of nuclear track emulsion exposed to thermal neutrons and Cf source

    Czech Academy of Sciences Publication Activity Database

    Mamatkulov, K. Z.; Ambrožová, Iva; Artemenkov, D. A.; Bradnova, V.; Kamanin, D. V.; Kattabekov, R. R.; Majling, Lubomír; Marey, A.; Ploc, Ondřej; Rusakova, V. V.; Stanoeva, R.; Turek, Karel; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.

    Vol. 675. Bristol: IOP Publishing, Ltd., 2016, s. 022012. ISSN 1742-6588. [International Conference on Particle Physics and Astrophysics . Moscow (RU), 05.10.2015-10.10.2015] R&D Projects: GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : nuclear track emulsion Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  12. Structure of Al-CF composites obtained by infiltration methods

    Directory of Open Access Journals (Sweden)

    A. Dolata-Grosz

    2011-04-01

    Full Text Available The structure of the composites obtained in infiltration processes 2D and 3D carbon preform by liquid Al alloy have been presented in thispaper. An aluminum alloy with silicon and manganese AlSi9Mn (trimal 37-TR37 was applied in the researches. As the reinforcementused carbon perform prepared with various protective barriers such as the nickel coating, the coating of silicon carbide and pyrolyticcarbon coating. Carbon preforms was prepared at the Institute for Lightweight Structures and Polymer Technology (ILK TU Dresden andat the Institute of Technology and Ceramic Systems (Fraunhofer-IKTS. The process of infiltration of carbon perform by liquid aluminiumalloy was carried out using a pressure-vacuum infiltration on the Degussa press and gas-pressure infiltration (GPI in an autoclavedesigned and built at the Department of Materials Technology at the Silesian University of Technology. The obtained composites werecharacterized by a regular shape, with no surface casting defects. The best connection of components was observed in AlSi9Mn/Cf(Nicomposite, obtained by gas-pressure infiltration method (GPI. On metallographic specimens, good interface between fibres and thealuminium matrix were observed. The obtained research results justify the application of nickel coatings on the fibres. During the failurecrack propagated across fiber. There was no presence of aluminum carbide on the fiber-matrix. It can be assumed that the composite willbe characterized by the good mechanical properties. However, this requires further experimental verification planned in the next stage of research, in the project realized within the DFG program: "3D textile reinforced aluminium matrix composites for complex loadingsituations in lightweight automobile and machine parts".

  13. Absolute number density and kinetic analysis of CF, CF{sub 2} and C{sub 2}F{sub 4} molecules in pulsed CF{sub 4}/H{sub 2} rf plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stepanov, Sergey

    2010-04-26

    Tunable Diode Laser Absorption Spectroscopy in the mid InfraRed spectral range (IR-TDLAS) has been applied to investigate the behaviour of CF, CF{sub 2} and C{sub 2}F{sub 4} species produced in pulsed CF{sub 4}/H{sub 2} capacitively coupled radio frequency plasmas (13.56 MHz CCP). This experimental technique was shown to be suitable for temporally resolved measurements of the absolute number density of the target molecules in the studied fluorocarbon discharges. The temporal resolution of about 20..40 ms typically achieved in the standard data acquisition mode (''stream mode'') was sufficient for the real-time measurements of CF{sub 2} and C{sub 2}F{sub 4}, but not of CF whose kinetics was observed to be much faster. Therefore, a more sophisticated approach (''burst mode'') providing a temporal resolution of 0.94 ms was established and successfully applied to CF density measurements. In order to enable the TDLAS measurements of the target species, preliminary investigations on their spectroscopic data had been carried out. In particular, pure C{sub 2}F{sub 4} has been produced in laboratory by means of vacuum thermal decomposition (pyrolysis) of polytetrafluoroethylene and used as a reference gas. Therefore, an absorption structure consisting of several overlapping C{sub 2}F{sub 4} lines around 1337.11 cm{sup -1} was selected and carefully calibrated, which provided the first absolute measurements of the species by means of the applied experimental technique. The absolute number density traces measured for CF, CF{sub 2} and C{sub 2}F{sub 4} in the studied pulsed plasmas were then analysed, in which two differential balance equations were proposed for each of the species to describe their behaviour during both ''plasma on'' and ''plasma off'' phases. Analytical solutions of the balance equations were used to fit the experimental data and hence to deduce important information on the

  14. The legacy of Cf-252 operations at Savannah River Technology Center: Continuous releases of radioiodine to the atmosphere

    International Nuclear Information System (INIS)

    The iodine isotopes I-132, 1-133, I-134, and I-135, which have half-lives ranging from 53 minutes to 21 hours, are measured in the atmospheric effluent from the Savannah River Technology Center (SRTC) at the Savannah River Site (SRS) near Aiken, South Carolina. SRS is operated by Westinghouse Savannah River Company for the US Department of Energy (DOE). The isotopes' release rates range from 10 to 300 microcuries per week compared to the rate. The resulting annual dose from all iodine isotopes is minor; it comprises 0.01 percent of the total offsite dose due to atmospheric releases from SRS in 1990. Circumstantial evidence indicates the radioiodine originates from traces of unencapsulated Cf-252. The determination that spontaneous fission of Cf-252 is the source of the radioiodine has several ramifications. Radioactive fission-product isotopes of the noble gas elements krypton and xenon must also be released. Noble gases are more volatile and mobile than iodine. Also, the released iodine isotopes decay to xenon isotopes. The noble gases decay to non-gaseous elements that are transported along with radioiodine to the terrestrial environment by deposition from the SRTC plume. Only Sr-89 is believed to accumulate sufficiently in the environment to approach detectable levels. Given similar conditions in earlier years, releases of short-lived radioiodine have occurred undetected in routine monitoring since the early 1970s. Release rates 20 years ago would have been 200 times greater than current release rates. This report documents preliminary experiments conducted by SRTC and Environmental Monitoring Section (EMS) scientists. The release process and the environmental impact of fission products from Cf-252 should be thoroughly researched

  15. Beam-Port Design of a Radiobiological Dosimetry Experiment for 10B-Enhanced 252Cf Brachytherapy

    International Nuclear Information System (INIS)

    It has been previously suggested that the incorporation of 10B-labeled drugs into tumor cells might significantly increase the dose to the peripheral tumor cells in 252Cf brachytherapy. The dose enhancement comes from the thermal neutron capture reactions of 10B(n, α)7Li. As a new cancer treatment modality, this so-called 10und B-und Enhanced 252und Cf und Brachyund therapy (BECBT) is currently being commercialized by Isotron. One of the challenges for implementing BECBT has been to determine the maximum tolerable dose (MTD) to the normal tissue surrounding a tumor. Because the relative biological effectiveness for the 10B(n, α)7Li reaction products is greater than that for fission neutrons, the MTD should decrease as 10B concentration increases for BECBT. To more precisely determine the MTD for BECBT, we intend to conduct both in vitro (cell culture) and in vivo (rat) experiments with a 50-mg 252Cf source. We will use cell survival fraction and normal brain necrosis as the biological end points for the cell-culture experiments and rat experiments, respectively. To carry out these experiments, the neutron field to which the samples are exposed must contain a significant portion of thermal neutrons. The rat experiments further require the use of a very small and well-collimated neutron beam to effectively irradiate the rat brain while minimizing the dose to its whole body. This paper discusses the design criteria for the experimental neutron beam port and the computational work leading to its optimal configuration

  16. High-Spin Structures in the N = 153 Nucleus 251Cf

    Science.gov (United States)

    Qiu, Y.; Hota, S. S.; Chowdhury, P.; Guess, C. J.; Jackson, E. G.; Lister, C. J.; Prasher, V. S.; Khoo, T. L.; Carpenter, M. P.; Janssens, R. V. F.; Greene, J.; Ahmad, I.; Seweryniak, D.; Zhu, S.; Albers, M.; Alcorta, M.; Bertone, P. F.; Chen, J.; Chiara, C. J.; Hoffman, C. R.; Kondev, F. G.; Lauritsen, T.; Tandel, S. K.

    2013-10-01

    In continuation of our exploration of band structures in neutron-rich Cf nuclei using inelastic and transfer reactions, we report new spectroscopic observations in the 251Cf nucleus. High-spin states of neutron-rich Cf nuclei were populated using a 208Pb beam from the ATLAS facility at Argonne, incident on a radioactive target mixture of 249 , 250 , 251Cf. Prompt γ rays were detected by the Gammasphere array. Both signatures of the ground state band of 251Cf were observed for the first time, with enhanced signal-to-noise achieved through appropriate gates on sum energy and fold parameters. Assignment of the band structure to 251Cf is via coincidence with Cf X-rays as well as the excitation of the 208Pb beam partner. Configurations are assigned to the observed band from experimental M1/E2 branching ratios from clean decays within the band. Further data analysis is in progress, and the new results will be discussed in the context of physics of the highest neutron orbitals accessible to spectroscopy in the A = 250 region. Work supported by U.S. Department of Energy.

  17. Isotopic yield in cold binary fission of even-even $^{244-258}$Cf isotopes

    CERN Document Server

    Santhosh, K P; Krishnan, Sreejith

    2016-01-01

    The cold binary fission of even-even 244-258Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. It is found that highest yield for 244,246,248Cf isotopes are for the fragments with isotope of Pb (Z=82) as one fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the fragments with isotope of Hg (Z=80) as one fragment. In the case of 254,256,258Cf isotopes the highest yield is for the fragments with Sn (Z=50) as one fragment. Thus, the fragment combinations with maximum yield reveal the role of doubly magic and near doubly magic nuclei in binary fission. It is found that asymmetric splitting is favoured for Cf isotopes with mass number A 252. In the case of Cf isotope with A=252, there is an equal probability for asymmetric and symmetric splitti...

  18. Trifluoroselenoacetic acid, CF(3)C(O)SeH: preparation and properties.

    Science.gov (United States)

    Gómez Castaño, Jovanny A; Romano, Rosana M; Beckers, Helmut; Willner, Helge; Della Védova, Carlos O

    2010-11-01

    The hitherto unknown trifluoroselenoacetic acid was prepared through the reaction of trifluoroacetic acid with Woollins' reagent. The compound was fully characterized by mass spectrometry, (1)H, (19)F, (77)Se, and (13)C NMR, UV-visible, IR and Raman spectroscopy, and the boiling point at 46 °C was estimated from the vapor pressure curve. An IR matrix isolation study revealed the presence of two different syn-anti and anti-syn conformers. The IR spectra of the two stereoisomers have been assigned, aided by DFT, and ab initio calculations. The UV photolysis of Ar matrix isolated CF(3)C(O)SeH yielded CO, OCSe, CF(3)SeH, and CHF(3). Apart from CF(3)SeH, these products were also obtained by vacuum flash-pyrolysis (310 °C) of gaseous CF(3)C(O)SeH. Instead of CF(3)SeH, CF(2)Se, and HF were detected among the pyrolysis products. The different decomposition pathways of CF(3)C(O)SeH are discussed. PMID:20879731

  19. Upper limits for the rate constants of the reactions of CF3O2 and CF3O radicals with ozone at 295 K

    DEFF Research Database (Denmark)

    Nielsen, O.J.; Sehested, J.

    Using the pulse radiolysis UV absorption technique and subsequent simulations of experimental absorption transients at 254 and 276 nm, upper limits of the rate constants for the reactions of CF3O2 and CF3O radicals with ozone were determined at 295 K, CF3O2+O3-->CF3O+2O2 (4), CF3O+O3-->CF3O2+O2 (......). The upper limits were derived as k4 < 0.5 x 10(-14) cm3 molecule-1 s-1, and k5 <1 x 10(-13) cm3 molecule-1 s-1. Results are discussed in the context of the atmospheric chemistry and ozone depletion by hydrofluorocarbons.......Using the pulse radiolysis UV absorption technique and subsequent simulations of experimental absorption transients at 254 and 276 nm, upper limits of the rate constants for the reactions of CF3O2 and CF3O radicals with ozone were determined at 295 K, CF3O2+O3-->CF3O+2O2 (4), CF3O+O3-->CF3O2+O2 (5...

  20. On the ClC halogen bond: a rotational study of CF3Cl-CO.

    Science.gov (United States)

    Caminati, Walther; Evangelisti, Luca; Feng, Gang; Giuliano, Barbara M; Gou, Qian; Melandri, Sonia; Grabow, Jens-Uwe

    2016-07-21

    The rotational spectra of two isotopologues (CF3(35)Cl-CO and CF3(37)Cl-CO) of the CF3Cl-CO adduct have been investigated and analyzed using supersonic-jet Fourier transform microwave spectroscopy, and found to have the features of a symmetric top. Rotational, centrifugal distortion, and nuclear quadrupole ((35)Cl and (37)Cl) coupling constants have been precisely obtained from high-resolution measurements. The two subunits of the complex are held together via a ClC halogen bond interaction. Information on the internal dynamics and the dissociation energy of the complex is provided. PMID:27049637

  1. Hydrophobic treatment on polymethylmethacrylate surface by nanosecond-pulse DBDs in CF4 at atmospheric pressure

    International Nuclear Information System (INIS)

    Highlights: • Increase in hydrophobicity on PMMA is achieved after the DBD treatment in CF4, and the water contact angle can increase from 68° to 100° after treatment. • Nanosecond-pulse DBD is used for the surface treatment and the power density is about 114.8 mW/cm2. • The effects of applied voltage, CF4 flow, and time on plasma treatment are investigated. • Plasma treatment causes morphological change, significantly increases the roughness of the surface, and introduces fluorine-containing groups into the polymethylmethacrylate surface. • Hydrophobic behavior of the treated PMMA surface is slightly affected by the aging effect. - Abstract: Nanosecond-pulse dielectric barrier discharge (DBD) can provide non-thermal plasmas with extremely high energy and high density, which can result in a series of complicated physical and chemical reactions in the surface treatment of polymers. Therefore, in this paper, hydrophobic treatment of polymethylmethacrylate (PMMA) surface is conducted by nanosecond-pulse DBD in carbon tetrafluoride (CF4) at atmospheric pressure. Investigations on surface morphology and chemical composition before and after the DBD treatment in CF4 are conducted with the contact angle measurement, atomic force microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectrometer. The effects of the applied voltage, CF4 flow rate, and treatment time on the hydrophobic modification are studied. Results show that the contact angles of the treated PMMA surface increases with the applied voltage, and it could be greatly affected by the CF4 flow rate and the treatment time. The water contact angle can increase from 68° to 100° after the treatment. Furthermore, both surface morphology and chemical composition of the PMMA samples are changed. Both the increase of the surface roughness and the occurrence of fluorine-containing functional groups on the PMMA surface treated by DBD in CF4 lead to the hydrophobicity improvement of

  2. The Dry Etching of TiN Thin Films Using Inductively Coupled CF4/Ar Plasma

    OpenAIRE

    Chang-Il Kim; Young-Hee Joo; Han-Soo Kim; Jong-Chang Woo; Chang-Auck Choi

    2013-01-01

    In this study, we changed the input parameters (gas mixing ratio, RF power, DC bias voltage, and process pressure),and then monitored the effect on TiN etch rate and selectivity with SiO2. When the RF power, DC-bias voltage, andprocess pressure were fixed at 700 W, - 150 V, and 15 mTorr, the etch rate of TiN increased with increasing CF4 contentfrom 0 to 20 % in CF4/Ar plasma. The TiN etch rate reached maximum at 20% CF4 addition. As RF power, DC biasvoltage, and process pressure increased, a...

  3. Energy levels of 247Cm populated in the α decay of 98251Cf

    International Nuclear Information System (INIS)

    α -Particle, conversion-electron, and γ -ray singles spectra of 251Cf sources containing few Bq activities were measured with high-resolution semiconductor detectors. α-γ coincidence and level half-life measurements were also performed. On the basis of these measurements the following single-particle states have been identified in 247Cm : 9/2 - [734] , 0 keV; 5/2 + [622] , 227.4 keV; 7/2 + [624] , 285.4 keV; 1/2 + [620] , 404.9 keV; 1/2 + [631] , 518.6 keV . The measured single-particle energies are in good agreement with energies calculated with a Woods-Saxon single-particle potential. From the measured half-life of the 227.4-keV level and the E3 branching ratio, a B(E3) value of 5 W.u. has been deduced between the 5/2 + [622] and 9/2 - [734] bands. The large B(E3) value is an indication of octupole mixing in the 227.4-keV level

  4. Two-phase flow measurements with 252Cf: Design aspects and considerations

    International Nuclear Information System (INIS)

    For many years 252Cf has been used for measuring moisture content, particularly in the ground's soil, by detecting the amount of slowing down (thermalization) of the source's fission neutrons by the hydrogen nuclei in water. The same concept has been employed for measuring the phase volume fraction in two-phase flows. Although two-phase boiling water measurements are in principle similar to those relating to moisture content, they present different challenges. Unlike the extended, stable, and reasonably uniform medium of the ground, two-phase flow measurements are conducted for a limited amount of fluid enclosed within a duct with metallic or polymer walls, and the phenomenon evolves with time, often rapidly, as phase transformation occurs in a heterogeneous fashion. These aspects demand special attention to design details. Although the principle of using neutron slowing down to measure hydrogen content is basic and straightforward, its application in a confined and evolving medium such as two-phase flow can be challenging. This paper identifies some of these challenges and presents some approaches for dealing with them

  5. Deformation effects in the alpha accompanied cold ternary fission of even-even 244-260Cf isotopes

    Science.gov (United States)

    Santhosh, K. P.; Krishnan, Sreejith

    2016-04-01

    Within the unified ternary fission model (UTFM), the alpha accompanied ternary fission of even-even 244-260Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. For the alpha accompanied ternary fission of the 244Cf isotope, the highest yield is obtained for the fragment combination 108Ru + 4He + 132Te, which contains the near doubly magic nucleus 132Te ( N = 80, Z = 52). In the case of 246Cf and 248Cf isotopes, the highest yield is obtained for the fragment combinations with the near doubly magic nucleus 134Te ( N = 82, Z = 52) as the heaviest fragment. The highest yield obtained for 250Cf, 252Cf, 254Cf, 256Cf, 258Cf and 260Cf isotopes is for the fragment combination with the doubly magic nucleus 132Sn ( N = 82), Z = 50 as the heaviest fragment. We have included the effect of deformation and orientation of fragments and this has revealed that in addition to the closed shell effect, ground-state deformation also plays an important role in the calculation of the relative yield of favorable fragment combinations. The computed isotopic yields for the alpha accompanied ternary fission of the 252Cf isotope are found to be in agreement with the experimental data. The emission probability and kinetic energy of the long-range alpha particle is calculated for the various isotopes of Cf and are found to be in good agreement with the experimental data.

  6. Extending netCDF and CF conventions to support enhanced Earth Observation Ontology services: the Prod-Trees project

    Science.gov (United States)

    Mazzetti, Paolo; Valentin, Bernard; Koubarakis, Manolis; Nativi, Stefano

    2013-04-01

    Access to Earth Observation products remains not at all straightforward for end users in most domains. Semantically-enabled search engines, generally accessible through Web portals, have been developed. They allow searching for products by selecting application-specific terms and specifying basic geographical and temporal filtering criteria. Although this mostly suits the needs of the general public, the scientific communities require more advanced and controlled means to find products. Ranges of validity, traceability (e.g. origin, applied algorithms), accuracy, uncertainty, are concepts that are typically taken into account in research activities. The Prod-Trees (Enriching Earth Observation Ontology Services using Product Trees) project will enhance the CF-netCDF product format and vocabulary to allow storing metadata that better describe the products, and in particular EO products. The project will bring a standardized solution that permits annotating EO products in such a manner that official and third-party software libraries and tools will be able to search for products using advanced tags and controlled parameter names. Annotated EO products will be automatically supported by all the compatible software. Because the entire product information will come from the annotations and the standards, there will be no need for integrating extra components and data structures that have not been standardized. In the course of the project, the most important and popular open-source software libraries and tools will be extended to support the proposed extensions of CF-netCDF. The result will be provided back to the respective owners and maintainers for ensuring the best dissemination and adoption of the extended format. The project, funded by ESA, has started in December 2012 and will end in May 2014. It is coordinated by Space Applications Services, and the Consortium includes CNR-IIA and the National and Kapodistrian University of Athens. The first activities included

  7. A new type-B cask design for transporting 252Cf

    International Nuclear Information System (INIS)

    A project to design, certify, and build a new US Department of Energy (DOE) Type B container for transporting >5 mg of 252Cf is more than halfway to completion. This project was necessitated by the fact that the existing Oak Ridge National Laboratory (ORNL) Type B containers were designed and built many years ago and thus do not have the records and supporting data that current regulations require. Once the new cask is available, it will replace the existing Type B containers. The cask design is driven by the unique properties of 252Cf, which is a very intense spontaneous fission neutron source and necessitates a large amount of neutron shielding. The cask is designed to contain up to 60 mg of 252Cf in the form of californium oxide or californium oxysulfate, in pellet, wire, or sintered material forms that are sealed inside small special-form capsules. The new cask will be capable of all modes of transport (land, sea, and air). The ORNL team, composed of technical and purchasing personnel and using rigorous selection criteria, chose NAC, International (NAC), as the subcontractor for the project. In January 1997, NAC started work on developing the conceptual design and performing the analyses. The original design concept was for a tungsten alloy gamma shield surrounded by two concentric shells of NS-4-FR neutron shield material. A visit to US Nuclear Regulatory Commission (NRC) regulators in November 1997 to present the conceptual design for their comments resulted in a design modification when the question of potential straight-line cracking in the NS-4-FR neutron shield material arose. NAC's modified design includes offset, wedgelike segments of the neutron shield material. The new geometry eliminates concerns about straight-line cracking but increases the weight of the packaging and makes the fabrication more complex. NAC has now completed the cask design and performed the analyses (shielding, structural, thermal, etc.) necessary to certify the cask. The cask

  8. CF_4和惰性气体混合物的输运性质的计算%Calculation of Transport Properties of CF_4+Noble Gas Mixtures

    Institute of Scientific and Technical Information of China (English)

    Soodabeh Nikmanesh; Jalil Moghadasi; Mohammad Mehdi Papari

    2009-01-01

    The present work is concerned with determining the viscosity, diffusion, thermal diffusion factor and thermal conductivity of five equimolar binary gas mixtures including: CF_4-He, CF_4-Ne, CF_4-Ar, CF_4-Kr, CF_4-Xe from the principle of corresponding states of viscosity by the inversion technique. The Lennard-Jones (12-6) model potential is used as the initial model potential. The calculated interaction potential energies obtained from the inversion procedure is employed to reproduce the viscosities, diffusions, thermal diffusion factors, and thermal conductivities. The accuracies of the calculated viscosity and diffusion coefficients were 1% and 4%, respectively.

  9. Identification of new neutron-rich rare-earth nuclei produced in /sup 252/Cf spontaneous fission

    CERN Document Server

    Greenwood, R C; Gehrke, R J; Meikrantz, D H

    1981-01-01

    A program of systematic study of the decay properties of neutron-rich rare-earth nuclei with 30 sCf spontaneous fission, is currently underway using the Idaho ESOL (Elemental Separation On Line) Facility. The chemistry system used for the rare-earth elemental separations consists of two high-performance chromatography columns connected in series and coupled to the /sup 252 /Cf fission source via a helium gas-jet transport arrangement. The time delay for separation and initiation of gamma -ray counting with results which have been obtained to date with this system include the identification of a number of new neutron-rich rare-earth isotopes including /sup 155/Pm (t/sub 1/2/=48+or-4 s) and /sup 163/Gd (t/sub 1 /2/=68+or-3 s), in addition to 5.51 min /sup 158/Sm which was identified in an earlier series of experiments. (11 refs).

  10. PTC/NTC Behavior of PVDF Composites Filled with GF and CF

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-lei; ZHANG Guo; LI Ji-xin; LI Zhuo-shi; LIU Zhan-fang; LIU Xiu-qi

    2008-01-01

    Conductive polyvinylidene fluoride(PVDF) matrix composites filled with graphited fiber(GF) or carbon fiber(CF) were prepared by the melt-mixing method.The breakage and length distribution of the fibers in the polymer matrix were studied by scanning electron microscope(SEM) and optical microscope(OM) observations,respectively.The differences in the positive temperature coefficient(PTC) effects of the composites were mainly attributed to inter-fiber contact ability.The elimination of the negative temperature coefficient(NTC) effect for CF/PVDF composite was because of an increase in the viscosity of the polymer matrix.With the same filler content,CF could be more effective,to eliminate the NTC effect when compared with GF.Addition of 2% CF(mass fraction) in the PVDF composite with 7% GF(mass fraction) could effectively eliminate the NTC phenomenon of the composite.

  11. Symptoms, Diagnosis, Treatment & Living with CF | NIH MedlinePlus the Magazine

    Science.gov (United States)

    ... a sign of infection. Transition of Care Because people today with CF are living longer than ever the move from pediatric to adult care is very important. Children should learn as much as possible about their condition and ...

  12. Thinning and functionalization of few-layer graphene sheets by CF4 plasma treatment

    KAUST Repository

    Shen, Chao

    2012-05-24

    Structural changes of few-layer graphene sheets induced by CF4 plasma treatment are studied by optical microscopy and Raman spectroscopy, together with theoretical simulation. Experimental results suggest a thickness reduction of few-layer graphene sheets subjected to prolonged CF4 plasma treatment while plasma treatment with short time only leads to fluorine functionalization on the surface layer by formation of covalent bonds. Raman spectra reveal an increase in disorder by physical disruption of the graphene lattice as well as functionalization during the plasma treatment. The F/CF3 adsorption and the lattice distortion produced are proved by theoretical simulation using density functional theory, which also predicts p-type doping and Dirac cone splitting in CF4 plasma-treated graphene sheets that may have potential in future graphene-based micro/nanodevices.

  13. A study of the valence shell photoelectron and photoabsorption spectra of CF3SF5

    International Nuclear Information System (INIS)

    The outer valence shell photoelectron spectrum of CF3SF5 has been studied experimentally and theoretically. Synchrotron radiation has been used to record angle-resolved outer valence shell photoelectron spectra of CF3SF5 in the photon energy range 18-60 eV. These spectra have allowed photoelectron asymmetry parameters and branching ratios to be derived. The Outer Valence Green's Function approach has been employed to calculate the molecular orbital configuration and associated binding energies. A charge distribution analysis has also been obtained. Assignments have been proposed for the peaks observed in the photoelectron spectrum. The absolute photoabsorption cross section of CF3SF5 has been measured from threshold to 40 eV, and strongly resembles that of SF6. Assignments, involving intravalence transitions, have been proposed for some of the principal features appearing in the photoabsorption spectrum of CF3SF5

  14. Developmental mode in white-nosed shrub frog Philautus cf. leucorhinus

    OpenAIRE

    Gururaja, KV; Ramachandra, TV

    2006-01-01

    Direct development in amphibians bypassing intermediary tadpole stage has behavioural, evolutionary and ecological significance.This paper presents direct development in Philautus cf. leucorhinus, while comparing with other congeners of the Western Ghats.

  15. 75 FR 77570 - Airworthiness Directives; General Electric Company CF6 Series Turbofan Engines

    Science.gov (United States)

    2010-12-13

    ...The FAA proposes to supersede an existing airworthiness directive (AD) for General Electric (GE) CF6-45/-50 series and CF6-80A series turbofan engines with certain part number (P/N) side links of the five-link forward mount assembly installed. That AD currently requires an initial and repetitive visual inspection of the side links for cracks, and stripping and reapplying the Sermetel W coating......

  16. Prompt neutron multiplicity in correlation with fragments from spontaneous fission of 252Cf

    OpenAIRE

    GÖÖK Alf; Hambsch, Franz-Josef; Vidali, Marzio

    2014-01-01

    The spontaneous fission of 252Cf serves as an excellent benchmark of prompt emission in fission since experimental data can be obtained without the need of an incident beam. With the purpose of providing experimental data on the prompt fission neutron properties in correlation with fission fragment characteristics an experiment on 252Cf(SF) has been performed. In addition, the experiment serves as benchmark of setup and analysis procedures for measurements of fluctuations in the prompt neutro...

  17. Shortness of breath in a CF patient: not always the chest

    OpenAIRE

    Ainslie, Mark; Bright-Thomas, Roland

    2011-01-01

    The authors report the case of an adult with cystic fibrosis (CF) presenting with an episode of acute shortness of breath during an inpatient stay for infective exacerbation of CF. The treatment of bronchodilators and steroids for presumed airways disease was not effective and on review of the chest x-ray, it showed some evidence of pulmonary oedema. An echo showed a dilated left ventricle and globally reduced function. Serology came back positive for enterovirus which was in keeping with a d...

  18. Sensitivity of Chloride Efflux vs. Transepithelial Measurements in Mixed CF and Normal Airway Epithelial Cell Populations

    OpenAIRE

    Illek, Beate; Lei, Dachuan; Fischer, Horst; Gruenert, Dieter C.

    2011-01-01

    Background/Aims: While the Cl- efflux assays are relatively straightforward, their ability to assess the efficacy of phenotypic correction in cystic fibrosis (CF) tissue or cells may be limited. Accurate assessment of therapeutic efficacy, i.e., correlating wild type CF transmembrane conductance regulator (CFTR) levels with phenotypic correction in tissue or individual cells, requires a sensitive assay. Methods: Radioactive chloride (36Cl) efflux was compared to Ussing chamber analysis for me...

  19. Ostreopsis cf. ovata dynamics in the NW Mediterranean Sea in relation to biotic and abiotic factors.

    Science.gov (United States)

    Carnicer, Olga; Guallar, Carles; Andree, Karl B; Diogène, Jorge; Fernández-Tejedor, Margarita

    2015-11-01

    An expansion of the distribution of Ostreopsis cf. ovata, a dinoflagellate which produces palytoxin-like compounds, has been reported in recent years. Economical and social interests are affected by blooms, as they are responsible for respiratory and skin problems in humans and may cause damage to marine organisms. In order to identify the most influential environmental factors that trigger proliferations of O. cf. ovata in the area of the adjacent shallow rocky coast of the Ebro Delta (NW Mediterranean Sea) a three-year survey was performed on the metaphytic microalgae community growing on the macrophytes Jania rubens and Corallina elongata. Small-size diatoms were more abundant than dinoflagellates; O. cf. ovata was identified as the only species present from the genus. Seawater temperature was the primary driver defining the ecological niche of O. cf. ovata. Freshwater and groundwater fluxes were more pronounced in southern than in northern sites, which may have resulted in a distinct O. cf. ovata spatial distribution, with the highest records of abundance and more frequent blooms in the north. In consequence, negative correlations between the abundance of O. cf. ovata and nitrate concentrations and significant positive correlation with salinity were observed. The temporal pattern of O. cf. ovata dynamics from mid-July to early-November is probably due to the fact that this species is observed only above a certain threshold temperature of seawater. Metaphytic cells of O. cf. ovata were smaller in the northern site than in the south, possibly as a result of an increase in cell division, coinciding with higher abundance, and this could be an indicator of favorable conditions. Toxicity in planktonic cells was negatively correlated with cell abundance in the water column, achieving maximum concentrations of 25pg. PLTX eqcell(-1). PMID:26365038

  20. Measurement of electron temperatures and electron energy distribution functions in dual frequency capacitively coupled CF4/O2 plasmas using trace rare gases optical emission spectroscopy

    International Nuclear Information System (INIS)

    Measurements of electron temperatures (Te) and electron energy distribution functions (EEDFs) in a dual frequency capacitively coupled etcher were performed by using trace rare gas optical emission spectroscopy (TRG-OES). The parallel plate etcher was powered by a high frequency (60 MHz) ''source'' top electrode and a low frequency (13.56 MHz) ''substrate'' bottom electrode. Te first increased with pressure up to ∼20 mTorr and then decreased at higher pressures. Increasing the bottom rf power resulted in higher electron temperatures. Electron temperatures in 90% CF4+10% O2 plasmas were similar to those in 80% CF4+20% O2 plasmas. EEDF exhibited bi-Maxwellian characteristics with enhanced high energy tail, especially at pressures >20 mTorr.

  1. Measurement of the electron drift velocity in CF4 and CHF3 gas mixtures in the context of upcoming directional Dark Matter detectors

    CERN Document Server

    Billard, J; Bosson, G; Bourrion, O; Guillaudin, O; Lamblin, J; Richer, J P; Riffard, Q; Santos, D; Iguaz, F J; Lebreton, L; Maire, D

    2013-01-01

    The knowledge of the electron drift velocity is a key issue for directional detection of galactic Dark Matter as it is used for the 3D track reconstruction. The aim of this paper is to present a dedicated method for the measurement of the electron drift velocity with the MIMAC detector, using a pure CF4 gas and a CF4 + CHF3 gas mixture. This new measurement method uses high energy alpha tracks from a collimated source and includes a profile likelihood method associated to a modeling of the signal induced on the grid. In particular, we show that adding CHF3 allows us to lower the electron drift velocity while keeping almost the same Fluorine content of the gas mixture. We show that the drift velocity at 50 mbar is reduced by a factor of about 5 when considering 30% of CHF3, allowing to improve the three-dimensional track reconstruction.

  2. CF102 an A3 Adenosine Receptor Agonist Mediates Anti-Tumor and Anti-Inflammatory Effects in the Liver

    OpenAIRE

    Cohen, S.; Stemmer, S M; ZOZULYA, G.; Ochaion, A.; PATOKA, R.; Barer, F.; BAR-YEHUDA, S.; RATH-WOLFSON, L.; Jacobson, K. A.; Fishman, P

    2011-01-01

    The Gi protein-associated A3 adenosine receptor (A3AR) is a member of the adenosine receptor family. Selective agonists at the A3AR, such as CF101 and CF102 were found to induce anti-inflammatory and anti-cancer effects. In this study, we examined the differential effect of CF102 in pathological conditions of the liver. The anti-inflammatory protective effect of CF101 was tested in a model of liver inflammation induced by Concanavalin A (Con. A) and the anti-cancer effect of CF102 was examine...

  3. Induction of a germline mutation at a hypervariable mouse minisatellite locus by 252Cf radiation

    International Nuclear Information System (INIS)

    Male C3H/HeN mice were exposed to 252Cf radiation and mated with unirradiated C57BL/6N females F1 mice were analyzed for germline mutation at the paternally derived C3H/HeN allele of a hypervariable minisatellite locus, Ms6hm. This locus exhibited a high frequency of length change mutation spontaneously, and the mutation frequency of the paternally derived C3H/He allele in F1 mice born to unirradiated males was 8.4%. Exposure of male mice to 252Cf radiation resulted in even higher frequency of germline mutation. The spermatid stage germ cells were most sensitive to neutrons, and the mutation frequencies of the paternal allele were elevated to 18%, 26% and 24% for 0.35, 0.7 and 1.02 Gy of 252Cf radiation, respectively. Spermatozoa and spermatogonia stages were less sensitive and the mutation frequencies for 1.02 Gy of 252Cf radiation were 16% and 19%, respectively. The 252Cf radiation consisted of 35% gamma-rays and 65% neutrons. Assuming that these two radiations act additively, RBE of 252Cf neutrons for the induction of minisatellite mutation was calculated to be 5.9 for spermatozoa stage irradiation, 2.6 for spermatid stage irradiation and 6.5 for spermatogonia irradiation. (author)

  4. Signal-CF: A subsite-coupled and window-fusing approach for predicting signal peptides

    International Nuclear Information System (INIS)

    We have developed an automated method for predicting signal peptide sequences and their cleavage sites in eukaryotic and bacterial protein sequences. It is a 2-layer predictor: the 1st-layer prediction engine is to identify a query protein as secretory or non-secretory; if it is secretory, the process will be automatically continued with the 2nd-layer prediction engine to further identify the cleavage site of its signal peptide. The new predictor is called Signal-CF, where C stands for 'coupling' and F for 'fusion', meaning that Signal-CF is formed by incorporating the subsite coupling effects along a protein sequence and by fusing the results derived from many width-different scaled windows through a voting system. Signal-CF is featured by high success prediction rates with short computational time, and hence is particularly useful for the analysis of large-scale datasets. Signal-CF is freely available as a web-server at http://chou.med.harvard.edu/bioinf/Signal-CF/ or http://202.120.37.186/bioinf/Signal-CF/

  5. Hydrogen effects in hydrofluorocarbon plasma etching of silicon nitride: Beam study with CF+, CF2+, CHF2+, and CH2F+ ions

    International Nuclear Information System (INIS)

    Hydrogen in hydrofluorocarbon plasmas plays an important role in silicon nitride (Si3N4) reactive ion etching. This study focuses on the elementary reactions of energetic CHF2+ and CH2F+ ions with Si3N4 surfaces. In the experiments, Si3N4 surfaces were irradiated by monoenergetic (500-1500 eV) beams of CHF2+ and CH2F+ ions as well as hydrogen-free CF2+ and CF+ ions generated by a mass-selected ion beam system and their etching yields and surface properties were examined. It has been found that, when etching takes place, the etching rates of Si3N4 by hydrofluorocarbon ions, i.e., CHF2+ and CH2F+, are higher than those by the corresponding fluorocarbon ions, i.e., CF2+ and CF+, respectively. When carbon film deposition takes place, it has been found that hydrogen of incident hydrofluorocarbon ions tends to scavenge fluorine of the deposited film, reducing its fluorine content.

  6. The difluoromethylene (CF2) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF2 groups.

    Science.gov (United States)

    Wang, Yi; Callejo, Ricardo; Slawin, Alexandra M Z; O'Hagan, David

    2014-01-01

    The syntheses of palmitic acids and a nonadecane are reported with CF2 groups located 1,3 or 1,4 to each other along the aliphatic chain. Specifically 8,8,10,10- and 8,8,11,11-tetrafluorohexadecanoic acids (6b and 6c) are prepared as well as the singly modified analogue 8,8-difluorohexadecanoic acid (6a). Also 8,8,11,11-tetrafluorononadecane (27) is prepared as a pure hydrocarbon containing a 1,4-di-CF2 motif. The modified palmitic acids are characterized by differential scanning calorimetry (DSC) to determine melting points and phase behaviour relative to palmitic acid (62.5 °C). It emerges that 6c, with the CF2 groups placed 1,4- to each other, has a significantly higher melting point (89.9 °C) when compared to the other analogues and palmitic acid itself. It is a crystalline compound and the structure reveals an extended anti-zig-zag chain. Similarly 8,8,11,11-tetrafluorononadecane (27) adopts an extended anti-zig-zag structure. This is rationalized by dipolar relaxation between the two CF2 groups placed 1,4 to each other in the extended anti-zig-zag chain and suggests a design modification for long chain aliphatics which can introduce conformational stability. PMID:24454560

  7. Sequence analysis of the DNA-repair gene rad51 in the tardigrades Milnesium cf. tardigradum, Hypsibius dujardini and Macrobiotus cf. harmsworthi

    Directory of Open Access Journals (Sweden)

    Eliana A. Beltrán-Pardo

    2013-05-01

    Full Text Available Tardigrades are known for being resistant to extreme conditions, including tolerance to ionising and UV radiation in both the hydrated and the dehydrated state. It is known that these factors may cause damage to DNA. It has recently been shown that single and double DNA strand breaks occur when tardigrades are maintained for a long time in the anhydrobiotic state. This may suggest that perhaps tardigrades rely on efficient DNA repair mechanisms. Among all proteins that comprise the DNA repair system, recombinases such as RecA or Rad51 have a very important function: DNA exchange activity. This enzyme is used in the homologous recombination and allows repair of the damaged strand using homologous non-damaged strands as a template. In this study, Rad51 induction was evaluated by western blot in Milnesium cf. tardigradum, after exposure to gamma radiation. The Rad51 protein was highly induced by radiation, when compared to the control. The rad51 genes were searched in three tardigrades: Milnesium cf. tardigradum, Hypsibius dujardini and Macrobiotus cf. harmsworthi. The gene sequences were obtained by preparing and sequencing transcriptome libraries for H. dujardini and M. cf. harmsworthi and designing rad51 degenerate primers specific for M. cf. tardigradum. Comparison of Rad51 putative proteins from tardigrades with other organisms showed that they are highly similar to the corresponding sequence from the nematode Trichinella spiralis. A structure-based sequence alignment from tardigrades and other organisms revealed that putative Rad51 predicted proteins from tardigrades contain the expected motifs for these important recombinases. In a cladogram tree based on this alignment, tardigrades tend to cluster together suggesting that they have selective differences in these genes that make them diverge between species. Predicted Rad51 structures from tardigrades were also compared with crystalline structure of Rad51 in Saccharomyces cerevisiae. These

  8. Trifluoro methyl peroxynitrate (CF 3OONO 2): Temperature dependence of the UV absorption spectrum and atmospheric implications

    Science.gov (United States)

    Malanca, Fabio E.; Chiappero, Malisa S.; Argüello, Gustavo A.; Wallington, Timothy J.

    The ultraviolet absorption spectrum of gas phase CF 3OONO 2 has been measured over the wavelength range 200-340 nm at 233-300 K. Absorption cross-sections at wavelengths of 290-340 nm were found to increase significantly with increasing temperature. The UV spectra of CF 3C(O)Cl and CF 3C(O)F were measured and were consistent with previous work [Rattigan et al., 1993. Temperature-dependent absorption cross-sections of CF 3COCl, CF 3COF, CH 3COF, CCl 3CHO and CF 3COOH. Journal of Photochemistry and Photobiology A: Chemistry 73, 1-9]. Implications for the atmospheric chemistry of CF 3OONO 2 are discussed.

  9. Design of a system for the undersea exploration of manganese nodules by 252Cf neutron induced gamma ray analysis

    International Nuclear Information System (INIS)

    A system for in-situ-analysis of manganese nodules has been designed. It permits the investigation of the concentrations of Ni, Cu and Co in concretions on the deep sea bottom. The surface sediments are collected by a suction system and conveyed into a tank where they are irradiated by neutrons emitted from a 252Cf source. The neutron-capture gamma rays are analyzed by a cooled Ge(Li) detector system. At the same time the bulk density of the nodules is measured by 60Co irradiation and a NaI(Tl) detector. The total device has an analysis cycle of about 15 minutes. It is towed by a ship over the sea bottom. (U.S.)

  10. A Monte Carlo comparison of PGNAA system performance using 252Cf neutrons, 2.8-MeV neutrons and 14-MeV neutrons

    Science.gov (United States)

    Naqvi, A. A.

    2003-10-01

    Monte Carlo simulations were carried out to compare performance of a 252Cf neutron and a 14-MeV neutron-based prompt γ-ray neutron activation analysis (PGNAA) system with that of the 2.8-MeV neutron-based PGNAA system at King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia. Since the energy of neutron beam used in the KFUPM PGNAA system is very close to that produced by a DD neutron generator, performance comparison between a DD and a DT neutron generator-based PGNAA system is highly desired. For the sake of comparison, the calculations were carried out for the PGNAA system with geometry similar to the KFUPM PGNAA system. These calculations were required to determine improvement in performance of the KFUPM PGNAA system if its 2.8-MeV neutron source is replaced by a 252Cf neutron source or a 14-MeV neutron source. Results of the calculations revealed that the geometry of the 252Cf neutron and the 2.8-MeV neutron-based PGNAA system are not significantly different but the geometry of the 14-MeV neutron-based system is significantly different from that of the 2.8-MeV neutron-based PGNAA system. Accordingly, the prompt γ-ray yields from the 252Cf neutron and the 2.8-MeV neutron-based PGNAA system is comparable but prompt γ-ray yields from 14-MeV neutron-based PGNAA system are about three times smaller than that from the 2.8-MeV neutron-based PGNAA system. This study has shown that performance of the 252Cf neutron-based PGNAA system is comparable with that of the 2.8-MeV neutron-based PGNAA system but the performance of the 14-MeV neutron-based PGNAA system is poorer than that of the 2.8-MeV neutron-based PGNAA system.

  11. A Monte Carlo comparison of PGNAA system performance using {sup 252}Cf neutrons, 2.8-MeV neutrons and 14-MeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A. E-mail: aanaqvi@kfupm.edu.sa

    2003-10-01

    Monte Carlo simulations were carried out to compare performance of a {sup 252}Cf neutron and a 14-MeV neutron-based prompt {gamma}-ray neutron activation analysis (PGNAA) system with that of the 2.8-MeV neutron-based PGNAA system at King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia. Since the energy of neutron beam used in the KFUPM PGNAA system is very close to that produced by a DD neutron generator, performance comparison between a DD and a DT neutron generator-based PGNAA system is highly desired. For the sake of comparison, the calculations were carried out for the PGNAA system with geometry similar to the KFUPM PGNAA system. These calculations were required to determine improvement in performance of the KFUPM PGNAA system if its 2.8-MeV neutron source is replaced by a {sup 252}Cf neutron source or a 14-MeV neutron source. Results of the calculations revealed that the geometry of the {sup 252}Cf neutron and the 2.8-MeV neutron-based PGNAA system are not significantly different but the geometry of the 14-MeV neutron-based system is significantly different from that of the 2.8-MeV neutron-based PGNAA system. Accordingly, the prompt {gamma}-ray yields from the {sup 252}Cf neutron and the 2.8-MeV neutron-based PGNAA system is comparable but prompt {gamma}-ray yields from 14-MeV neutron-based PGNAA system are about three times smaller than that from the 2.8-MeV neutron-based PGNAA system. This study has shown that performance of the {sup 252}Cf neutron-based PGNAA system is comparable with that of the 2.8-MeV neutron-based PGNAA system but the performance of the 14-MeV neutron-based PGNAA system is poorer than that of the 2.8-MeV neutron-based PGNAA system.

  12. Super-hydrophobicity and oleophobicity of silicone rubber modified by CF4 radio frequency plasma

    International Nuclear Information System (INIS)

    Owing to excellent electric properties, silicone rubber (SIR) has been widely employed in outdoor insulator. For further improving its hydrophobicity and service life, the SIR samples are treated by CF4 radio frequency (RF) capacitively coupled plasma. The hydrophobic and oleophobic properties are characterized by static contact angle method. The surface morphology of modified SIR is observed by atom force microscope (AFM). X-ray photoelectron spectroscopy (XPS) is used to test the variation of the functional groups on the SIR surface due to the treatment by CF4 plasma. The results indicate that the static contact angle of SIR surface is improved from 100.7 deg. to 150.2 deg. via the CF4 plasma modification, and the super-hydrophobic surface of modified SIR, which the corresponding static contact angle is 150.2 deg., appears at RF power of 200 W for a 5 min treatment time. It is found that the super-hydrophobic surface ascribes to the coaction of the increase of roughness created by the ablation action and the formation of [-SiFx(CH3)2-x-O-]n (x = 1, 2) structure produced by F atoms replacement methyl groups reaction, more importantly, the formation of [-SiF2-O-]n structure is the major factor for super-hydrophobic surface, and it is different from the previous studies, which proposed the fluorocarbon species such as C-F, C-F2, C-F3, CF-CFn, and C-CFn, were largely introduced to the polymer surface and responsible for the formation of low surface energy.

  13. Deformation effects in the alpha accompanied cold ternary fission of even-even $^{244-260}$Cf isotopes

    CERN Document Server

    Santhosh, K P

    2016-01-01

    Within the Unified ternary fission model (UTFM), the alpha accompanied ternary fission of even-even $^{244-260}$Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. For the alpha accompanied ternary fission of 244^Cf isotope, the highest yield is obtained for the fragment combination 108^Ru+4^He+132^Te, which contain near doubly magic nuclei 132^Te (N=80, Z=52). In the case of 246^Cf and 248^Cf isotopes, the highest yield is obtained for the fragment combinations with near doubly magic nuclei 134^Te (N=82, Z=52) as the heavier fragment. The highest yield obtained for 250^Cf, 252^Cf, 254^Cf, 256^Cf, 258^Cf and 260^Cf isotopes is for the fragment combination with doubly magic nuclei 132^Sn (N=82, Z=50) as the heavier fragment. We have included the effect of deformation and orientation of fragments and this has revealed that in addition to closed shell effect, ground state deformation also plays an important role in the calculation of relative yield of fav...

  14. Level structures of 110,111,112,113Rh from measurements on 252Cf

    International Nuclear Information System (INIS)

    Level schemes of 111Rh and 113Rh are proposed from the analysis of γ-γ-γ coincidence data from a 252Cf spontaneous fission source with Gammasphere. These schemes have the highest excitation energies and spins yet established in these nuclei, as well as weakly populated bands not reported in earlier fission- γ work. From these data, information on shapes is inferred. By analogy with lighter Z=45 odd-even isotopes, tentative spins and parities are assigned to members of several rotational bands. In this region triaxial nuclear shapes are known to occur, and we carried out calculations for 111Rh and 113Rh with the triaxial-rotor-plus-particle model. The 7/2+πg9/2 bands of both nuclei, as well as lighter isotopes studied by others, show similar signature splitting. Our model calculations give a reasonable fit to the signature splitting, collective sidebands, and transition probabilities at near-maximum triaxiality with γ≅28 deg. For the K=1/2+[431] band, experiment and model calculations do not fit well, which is accounted for by greater prolate deformation of the K=1/2+ band, a case of shape coexistence. Our data on 110,112Rh show no backbending and thus support the idea of the band crossing in the ground band of the odd-A neighbors being due to alignment of an h11/2 neutron pair. In 111,113Rh above the band crossing (spins ≅21/2(ℎ/2π)) the ground band appears to split, with two similar branches. We consider the possibility that chiral doubling may be involved, but there are not enough levels to determine that

  15. Inspection of CF188 composite flight control surfaces with neutron radiography

    International Nuclear Information System (INIS)

    At the Royal Military College of Canada's SLOWPOKE-2 Facility, a neutron radiography facility has been designed and installed using a small (20kWth), pool-type research reactor called the SLOWPOKE-2 (Safe Low Power c(K)ritical Experiment) as the neutron source. Since then, the research has continued along two fronts: developing applications and improving the quality of the neutron beam. The most interesting applications investigated to date has been the inspection of various metal ceramic composites and the inspection of the composite flight control surfaces of some of the CF188 Hornet aircraft. As part of the determination of the integrity of the aircraft, it was decided to inspect an aircraft with the highest flight house using both X- and neutron radiography. The neutron radiography and, to a lesser extent, X-radiography inspections completed at McClellan AFB revealed 93 anomalies. After returning to Canada, the component with the greatest structural significance, namely the right hand rudder from the vertical stabilizer, was removed from the aircraft and put through a rigorous program of numerous NDT inspections, including X-radiography (film and real-time), eddy current, ultrasonics (through transmission and pitch-catch), infrared thermography, and neutron radiography. Therefore, of all the techniques investigated, only through transmission ultrasonics and neutron radiography were able to identify large areas of hydration. However, only neutron radiography could identify the small areas of moisture and hydration. Given the structural significance of the flight control surfaces in modern fighter aircraft, even the smallest amounts of hydration could potentially lead to catastrophic results

  16. Standard test method for nondestructive assay of nuclear material in scrap and waste by passive-Active neutron counting using 252Cf shuffler

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers the nondestructive assay of scrap and waste items for U, Pu, or both, using a 252Cf shuffler. Shuffler measurements have been applied to a variety of matrix materials in containers of up to several 100 L. Corrections are made for the effects of matrix material. Applications of this test method include measurements for safeguards, accountability, TRU, and U waste segregation, disposal, and process control purposes (1, 2, 3). 1.1.1 This test method uses passive neutron coincidence counting (4) to measure the 240Pu-effective mass. It has been used to assay items with total Pu contents between 0.03 g and 1000 g. It could be used to measure other spontaneously fissioning isotopes such as Cm and Cf. It specifically describes the approach used with shift register electronics; however, it can be adapted to other electronics. 1.1.2 This test method uses neutron irradiation with a moveable Cf source and counting of the delayed neutrons from the induced fissions to measure the 235U equiva...

  17. Effect of Gd content on interfacial microstructures and mechanical properties of Cf/Mg composite

    International Nuclear Information System (INIS)

    Highlights: • The Gd element is prone to segregate to the interface between the fiber and matrix. • Interfacial products including Gd2O3 and Mg7Gd are observed at interface. • ILSS of Cf/Mg–3.2Gd composite is increased by 60.4% compare to that of Cf/Mg composite. - Abstract: Matrix alloying is an effective and convenient method to improve the interface bonding strength for continuous carbon fiber reinforced magnesium matrix composites. In this work, rare earth metal Gd was selected as an alloying element to improve the interface bonding of Cf/Mg composite. Cf/Mg composites with different Gd content were fabricated by pressure infiltration method. The effect of Gd addition on the interfacial microstructures and mechanical properties of the composites were investigated. The results showed that the rare earth Gd tended to segregate at interface area to form Gd2O3 layer and particle phase Mg7Gd. Both the interfacial products enhanced the interface bonding strength which can be identified by the increase of interlaminar shear strength (ILSS). In particular, the Gd addition promoted the ILSS and bending strength greatly, with an increase by 60.4% and 25.3% compared with Cf/Mg composite, respectively. The fracture surfaces of the composites were examined by scanning electron microscopy and micrographs were employed to explain the inherent relation between interface characterization and mechanical properties

  18. CfAIR2: Near Infrared Light Curves of 94 Type Ia Supernovae

    CERN Document Server

    Friedman, Andrew S; Marion, G H; Challis, Peter; Mandel, Kaisey S; Bloom, Joshua S; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcolm; Foley, Ryan; Klein, Christopher R; Starr, Dan L; Morgan, Adam; Rest, Armin; Blake, Cullen H; Miller, Adam A; Falco, Emilio E; Wyatt, William F; Mink, Jessica; Skrutskie, Michael F; Kirshner, Robert P

    2014-01-01

    CfAIR2 is a large homogeneously reduced set of near-infrared (NIR) light curves for Type Ia supernovae (SN Ia) obtained with the 1.3m PAIRITEL (Peters Automated InfraRed Imaging TELescope). This data set includes 4607 measurements of 94 SN Ia and 4 additional SN Iax observed from 2005-2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z~0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from maximum in the B-band. More than half of the light curves begin before the time of maximum and the coverage typically contains ~13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for supernova cosmology studies in the NIR. ...

  19. Atmospheric chemistry of CF3CFHCF2OCF3 and CF3CFHCF2OCF2H: Reaction with Cl atoms and OH radicals, degradation mechanism, and global warming potentials

    DEFF Research Database (Denmark)

    Wallington, TJ; Hurley, MD; Nielsen, OJ;

    2004-01-01

    Fourier transform infrared (FTIR) smog chamber techniques were used to measure k(Cl + CF3CFHCF2OCF3) = (4.09 +/- 0.42) x 10(-17), k(OH + CF3CFHCF2OCF3) = (1.43 +/- 0.28) x 10(-15), k(Cl + CF3CFHCF2OCF2H) = (6.89 +/- 1.29) x 10(-17), and k(OH + CF3CFHCF2OCF2H) = (1.79 +/- 0.34) x 10(-15) cm(3) mol...... respectively. The 100-year time horizon global warming potentials of CF3CFHCF2OCF3 and CF3CFHCF2OCF2H relative to CO2 are 4530 and 4340. Results are discussed with respect to the atmospheric chemistry of hydrofluoroethers....

  20. Evaluation of material properties considering thermal embrittlement for accelerated aged CF-8M and CF-8A cast austenitic stainless steel

    International Nuclear Information System (INIS)

    Cast austenitic stainless steel have been widely used for primary coolant piping in light water reactors. This material is subject to thermal embrittlement at reactor operating temperature. CF-8M and CF-8A cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. Thermal embrittlement results in spinodal decomposition of delta-ferrite leading to decreased fracture toughness. In this study, the specimens were prepared using an accelerated aging method. The measurement of ferrite content, Charpy impact test and J-R test were performed to verify the predicting equation for aged material properties. In case of above 25% ferrite content, predicted result of J-R curve might be non-conservative

  1. Tensile behavior of CF8-CPF8-304H and CF8M-CPF8M-316H stainless steel static and centrifugal castings

    International Nuclear Information System (INIS)

    We have analyzed the tensile behavior of 11 heats of grades CF8-CPF8-304H and 13 heats of grades CF8M-CPF8M-316H static and centrifugal castings from room temperature to 6500C. Except for anomalous conditions, the centrifugal castings exhibited uniform composition. All CPF8-304H centrifugal castings contained only radial columnar grains, but some CPF8M-316H castings had columnar, banded, or equiaxed structures. Ultimate tensile strength and total elongation were the properties in which castings showed the most inferiority to wrought material. With increasing ferrite content, 0.2% yield strength and ultimate tensile strength increased while uniform elongation, total elongation, and reduction of area decreased. Although centrifugal castings did not exhibit significant end-to-end variation in tensile behavior, the 0.2% yield strength displayed anisotropy, with axial and circumferential values being greater than radial

  2. Study of spatial distributions of F, H and CF2 radicals in DF CCP discharge in Ar/CF4 and Ar/CHF3 mixtures

    International Nuclear Information System (INIS)

    The comparative research of production and loss of atoms (F, H) and radicals (CF2), important for plasma processing, is carried out in DF CCP plasma in Ar/CF4 and Ar/CHF3 mixtures modeling two etching plasmas (fluorine-rich) and (fluorine-poor) respectively. Electron density, electron temperature and ion energy spectra are measured for single and dual frequency discharge modes. Spatial profiles of radical and atom densities are measured in both mixtures by using spatially resolved actinometry and UV absorption techniques. The opportunity for plasma-surface interaction control using spatial radical and atom density distributions is shown. The influence of high and low frequency powers on balance between surface and volume processes is discussed.

  3. Environmentally assisted cracking and irradiation embrittlement of CF-8 and CF-8M cast austenitic stainless steels in high-purity water

    International Nuclear Information System (INIS)

    Cast austenitic stainless steels (CASS) are used for components with complex geometries in the cooling system of light water reactors (LWRs). Due to both thermal ageing and irradiation embrittlement, the long-term performance of CASS materials is of concern. To assess the impact of thermal ageing and irradiation embrittlement on the cracking behaviour of CASS materials, crack growth rate and fracture toughness JR curve tests were carried out on CF-8 and CF-8M compact-tension specimens in high-purity water with low dissolved oxygen. The as-received and thermally aged CASS specimens were irradiated to 0.08 dpa to investigate the combined effect of thermal ageing and neutron irradiation. The crack growth rates of irradiated CASS materials were compared with previous results on unirradiated specimens. While no elevated cracking susceptibility was observed for the irradiated specimens at this dose level, a slightly better corrosion fatigue performance was found in the CF-8 than in CF-8M materials. Thermal ageing history had little effect on the crack growth behaviour in the test environment. Trans-granular cleavage-like cracking was the main fracture mode in the crack growth rate tests, and delta ferrite morphology could be seen in some areas on the fracture surfaces. Compared to thermal ageing, neutron irradiation had a dominant role in the fracture toughness JR curve tests. The loss of toughness due to neutron irradiation was much more significant in the as-received than in the thermally aged CASS specimens. The fracture toughness of CASS specimens was reduced to a similar level after neutron irradiation regardless of their thermal ageing history. This suggests a more rapid development of embrittlement in the as-received than in the thermally aged CASS specimens under neutron irradiation. (authors)

  4. SiCf/TC17复合材料拉伸行为研究%STUDY ON TENSILE BEHAVIOR OF SiCf/TC17 COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    张旭; 王玉敏; 杨青; 雷家峰; 杨锐

    2015-01-01

    研究了SiCf/TC17复合材料的室温、高温(773K)拉伸性能及其断裂机制.结果表明:SiCf/TC17复合材料室温、高温应力-应变曲线受纤维线弹性变形和基体屈服程度影响呈现不同的形状;室温断裂机制主要是反应层多次断裂、纤维一次断裂和基体脆性断裂等,高温断裂机制主要是纤维多次断裂、基体韧性断裂和大范围的界面脱黏等;纤维累计损伤理论适合于对SiCf/TC17复合材料断裂强度的估测,其中室温断裂强度符合临界断裂纤维数大于或等于3时的局部承担载荷模型,高温断裂强度符合均匀承担载荷模型.结合断裂机制和强度估算结果,详细论述了SiCf/TC17复合材料室温、高温拉伸断裂过程.

  5. TEA CO2 laser-induced reaction of CH3NO2 with CF2HCl: A mechanistic study

    Indian Academy of Sciences (India)

    Rajesh K Vatsa; Sisir K Sarkar; Jai P Mittal

    2001-08-01

    Dissociation of nitromethane has been observed when a mixture of CF2HCl and CH3NO2 is irradiated using pulsed TEA CO2 laser at 9R (24) line (1081 cm-1), which is strongly absorbed by CF2HCl but not by CH3NO2. Under low laser fluence conditions, only nitromethane dissociates, whereas at high fluence CF2HCl also undergoes dissociation, showing that dissociation occurs via the vibrational energy transfer processes from the TEA CO2 laser-excited CF2HCl to CH3NO2. Time-resolved infrared fluorescence from vibrationally excited CF2HCl and CH3NO2 molecules as well as UV absorption of CF2 radicals are carried out to elucidate the dynamics of excitation/dissociation and the chemical reactions of the dissociation products.

  6. Limiting field strength and electron swarm coefficients of the CF3I-SF6 gas mixture

    Science.gov (United States)

    de Urquijo, J.; Mitrani, A.; Ruíz-Vargas, G.; Basurto, E.

    2011-08-01

    We have measured the electron drift velocity, longitudinal diffusion, and the effective ionization coefficients in the gaseous mixture of CF3I-SF6 over the density-normalized electric field intensity E/N, from 375 to 500 Td (1 Td = 10-17 V cm2). A pulsed Townsend technique was used. Overall, the gas mixture compositions were varied from 50 to 90% CF3I. We have found that the limiting field strength E/Nlim of the CF3I-SF6 mixture is superior to that of CF3I-N2, and always higher than that of SF6. Moreover, over the whole mixture range, the range of the limiting field strength for the CF3I-SF6 mixture is 360-437 Td, these limits corresponding for pure SF6 and CF3I, respectively.

  7. Compatibility of SiCf/SiC composite exposed to liquid Pb-Li flow

    International Nuclear Information System (INIS)

    SiCf/SiC composites are candidate structural and functional materials for fusion blankets, attractive for their potential application for higher temperature liquid metal blankets compared to the range possible for metallic materials. However, the experimental data on the long term compatibility of SiCf/SiC composites with high temperature liquid metal is inadequate. To acquire parametric data on the compatibility of NITE SiCf/SiC composites with a high temperature liquid metal stream, the corrosion behavior was examined in liquid Pb-Li using a rotating disk apparatus. The materials used in this study were exposed to relative flow velocity of ∼10-37 cm/s at 900 deg. C for 1000 h. Oxidation layers were detected on the matrix and fiber near the surface exposed to liquid Pb-Li at 900 deg. C for 1000 h. Additional results for shorter exposure times and relationship to flow velocity are discussed.

  8. MoO3 trapping layers with CF4 plasma treatment in flash memory applications

    International Nuclear Information System (INIS)

    Highlights: • MoO3-based flash memories have been fabricated. • CF4 plasma treatment could enhance good memory performance. • Material analyses confirm that plasma treatment eliminated defects. • Fluorine atoms might fix the dangling bonds. - Abstract: In this research, we used MoO3 with CF4 plasma treatment as charge trapping layer in metal-oxide-high-k -oxide-Si-type memory. We analyzed material properties and electrical characteristics with multiple analyses. The plasma treatment could increase the trapping density, reduce the leakage current, expand band gap, and passivate the defect to enhance the memory performance. The MoO3 charge trapping layer memory with suitable CF4 plasma treatment is promising for future nonvolatile memory applications

  9. Electron drift velocities in fast Argon and CF4 based drift gases

    CERN Document Server

    van Apeldoorn, G

    1998-01-01

    98-063 Electron drift velocities in gas mixtures were measured in a tabletop experiment using a nitrogen laser to create the primary electrons. The maximum drift times for electrons in a 5 mm (10 mm) honeycomb drift cell at 2200 V anode voltage were 28 ns (53 ns) and 21 ns (61 ns) for Ar-Cf4-CH4 (75/18/6) and Ar-CF4-CO2 (68/27/5), respectively. Changing the ratio of the latter mix did not change the drift velocity very much. The gains of the gases are ~10^4 for a single primary electron. CF4 causes electron attachment. The measured drift times agree well with GARFIELD simulations.

  10. Comparison between magnetic enzyme-linked immunosorbent assay (MELISA) and complement fixation test (CF) in the diagnosis of paracoccidioidomycosis.

    Science.gov (United States)

    Pires de Camargo, Z; Unterkircher, C; Drouhet, E

    1986-02-01

    MELISA and CF were compared using sera from paracoccidioidomycosis patients before treatment and patients undergoing antimycotic treatment. With MELISA it was possible to distinguish different antibody levels in both groups of patients whereas such distinction was not observed by using CF tests. MELISA is thus an advantageous alternative to CF in the diagnosis of paracoccidioidomycosis, including the possibility of testing sera with anticomplementary activity. PMID:3701544

  11. The CfAO's Astronomy Course in COSMOS: Curriculum Design, Rationale, and Application

    OpenAIRE

    Cooksey, Kathy L.; Seagroves, Scott; Porter, Jason; Raschke, Lynne; Severson, Scott; Hinkley, Sasha

    2010-01-01

    From 2001 to 2007, COSMOS provided a teaching and outreach venue for the Center for Adaptive Optics Professional Development Program (CfAO PDP). COSMOS is a four-week residential mathematics and science summer program for high-school students organized by the University of California on four of its campuses. Two topical science courses comprised each COSMOS cluster. An astronomy course has always formed a basis for the CfAO PDP-affiliated cluster. The course included a variety of pedagogical ...

  12. Orientations of fragments emitted in binary cold fission of 252Cf

    International Nuclear Information System (INIS)

    The dependence of the driving potential on the orientation of fragments at scission is investigated for the case of cold fission of 252Cf. It is shown that in the case of cold fission the fragments exclusively emerge at scission in the pole-pole configuration. However, quantum fluctuations enable small deviations from this configuration during the tunnelling process. The mass yields of fission fragment pairs in the cold fission of 252Cf are computed for pole-pole and equator-equator orientations and are compared to the experimental data

  13. Atomic mass identification of CF-252 fission fragments using an NE-102 thin film detector

    International Nuclear Information System (INIS)

    The measurement of atomic number of low energy Cf-252 fission products using a three element thin film scintillation detector in conjunction with a residual energy solid state detector is described. Critical comparison of the separate spectra yielded by the three thin film elements is used to show both quantitative and qualitative consistency. Through the use of simple data handling techniques, increased resolution between peaks is easily obtained; the resultant spectrum for the distribution of both heavy and light fragments of Cf-252 is presented. The anticipated application of thin film scintillation techniques for event-by-event illucidation of decay schemes will also be discussed

  14. Experimental study of CF4 conical theta pinch plasma expanding into vacuum

    International Nuclear Information System (INIS)

    Langmuir probe, photodiode, and optical multichannel analyzer (OMA) measurements have been made on a pulsed CF4 conical theta pinch plasma. A cloud of CF4 gas was puffed into a conical theta pinch coil, converted to plasma, and propelled into the vacuum region ahead of the expanding gas cloud. At a position 67 cm away from the conical theta pinch coil, the plasma arrived in separate packets that were about 20 μs in duration. The average drift velocity of these packets corresponded to an energy of about 3 eV. The OMA measurements showed that the second packet contained neutral atomic fluorine as well as charged particles

  15. Quenching the scintillation in CF{sub 4} Cherenkov gas radiator

    Energy Technology Data Exchange (ETDEWEB)

    Blake, T. [Department of Physics, University of Warwick, Coventry (United Kingdom); D' Ambrosio, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Easo, S. [STFC Rutherford Appleton Laboratory, Didcot (United Kingdom); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Eisenhardt, S. [School of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Fitzpatrick, C. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne (Switzerland); Forty, R.; Frei, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Gibson, V. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Gys, T. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Harnew, N.; Hunt, P. [Department of Physics, University of Oxford, Oxford (United Kingdom); Jones, C.R. [Cavendish Laboratory, University of Cambridge, Cambridge (United Kingdom); Lambert, R.W. [Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam (Netherlands); Matteuzzi, C. [Sezione INFN di Milano Bicocca, Milano (Italy); Muheim, F. [School of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Papanestis, A., E-mail: antonis.papanestis@stfc.ac.uk [STFC Rutherford Appleton Laboratory, Didcot (United Kingdom); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Perego, D.L. [Sezione INFN di Milano Bicocca, Milano (Italy); Università di Milano Bicocca, Milano (Italy); Piedigrossi, D. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Plackett, R. [Imperial College London, London (United Kingdom); Powell, A. [Department of Physics, University of Oxford, Oxford (United Kingdom); and others

    2015-08-11

    CF{sub 4} is used as a Cherenkov gas radiator in one of the Ring Imaging Cherenkov detectors at the LHCb experiment at the CERN Large Hadron Collider. CF{sub 4} is well known to have a high scintillation photon yield in the near and far VUV, UV and in the visible wavelength range. A large flux of scintillation photons in our photon detection acceptance between 200 and 800 nm could compromise the particle identification efficiency. We will show that this scintillation photon emission system can be effectively quenched, consistent with radiationless transitions, with no significant impact on the photons resulting from Cherenkov radiation.

  16. Low Background Materials and Assay - A Supplement to the Cosmic Frontier CF1 Summary

    CERN Document Server

    Cooley, J; Hoppe, E W; Orrell, J L; Schnee, R W

    2013-01-01

    This White Paper provides a supplement to the Snowmass Summary from CF1 (Cosmic Frontier WIMP Direct Detection). It was largely prepared during the August 2013 Community Planning Meeting and relies on information gathered from the larger dark matter community. It is a more detailed answer to the CF1 Charge: "Identify the common infrastructure required to meet the scientifica and technical goals of dark matter direct detection." The community as a whole recognizes that sensitive searches for WIMPs require identification, quantification, and procurement of radiopure materials. The lack of sufficient resources in this area is a major project risk for future experiments and can limit scientific reach

  17. Modelling sorptionanddiffusionofNF3 and CF4 in Teflon AF perfluoropolymermembranes

    OpenAIRE

    Branken, D.J.; Krieg, H.M.; Lachmann, G.; Carstens, P.A.B.

    2014-01-01

    Molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations with Teflon AF2400 and Teflon AF1600 predicted diffusivities and solubilities of He and N2 that corresponded reasonably with available experimental data. The results of the MD simulations further showed that NF3 had a higher diffusivity than CF4 in both polymers and that the NF3/CF4 diffusion selectivity was 67% higher in Teflon AF1600 compared to Teflon AF200. However, because the GCMC simulations failed to offer a co...

  18. Modelling sorption and diffusion of NF3 and CF4 in Teflon AF perfluoropolymer membranes

    OpenAIRE

    Branken, D.J.; Krieg, H.M.; Lachmann, G.; Carstens, P.A.B.

    2014-01-01

    Molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations with Teflon AF2400 and Teflon AF1600 predicted diffusivities and solubilities of He and N2 that corresponded reasonably with available experimental data. The results of the MD simulations further showed that NF3 had a higher diffusivity than CF4 in both polymers and that the NF3/CF4 diffusion selectivity was 67% higher in Teflon AF1600 compared to Teflon AF200. However, because the GCMC simulations failed to offer a co...

  19. Home IV Antibiotic Therapy and Exercise Capacity in Children with CF: A Case Series

    OpenAIRE

    Cox, Narelle S.; McKay, Karen O.; Follett, Jennifer M.; Alison, Jennifer A

    2011-01-01

    Purpose: This case series describes the effect of home intravenous (IV) antibiotic therapy on spirometry and exercise capacity in a group of children with cystic fibrosis (CF). Methods: Outcomes from 10 children with CF who were prescribed a 14-day course of home IV antibiotics for a respiratory exacerbation are reported. All children performed spirometry and a modified shuttle test (MST) before and after 14-days of home IV therapy. Results: After 14 days, FEV1 increased by mean (± SE) 12 ± 4...

  20. Deformation effects in the alpha accompanied cold ternary fission of even-even $^{244-260}$Cf isotopes

    OpenAIRE

    Santhosh, K P; Krishnan, Sreejith

    2016-01-01

    Within the Unified ternary fission model (UTFM), the alpha accompanied ternary fission of even-even $^{244-260}$Cf isotopes has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential. For the alpha accompanied ternary fission of 244^Cf isotope, the highest yield is obtained for the fragment combination 108^Ru+4^He+132^Te, which contain near doubly magic nuclei 132^Te (N=80, Z=52). In the case of 246^Cf and 248^Cf isotopes, the highest yield is obtained fo...

  1. Solution and displacement in monolayer and multilayer binary films of SF6 and CF4 on graphite.

    Science.gov (United States)

    Thomas, Petros; Grogan, Michael D W; Hess, George B

    2015-09-21

    Infrared reflection absorption spectroscopy is used to study the evolution of binary physisorbed films on graphite. A predeposited monolayer of SF6 is exposed to slowly increasing pressure of CF4 at constant temperature between 80 and 113 K. Shifts in the frequencies of the dominant vibrational mode of each species due to resonant dipole-dipole coupling serve as proxies for the areal density of each species in the monolayer. If the initial SF6 film is far below saturation (coexistence with bulk solid), the SF6 can be largely displaced by continuous solution of CF4. However, if the initial SF6 layer is at or near saturation, a layer of CF4 condenses on top at a well defined CF4 pressure after only 2%-3% dilution of the SF6 layer. Simultaneously, most of the dissolved CF4 is withdrawn from the SF6 layer. With further increase in CF4 pressure, the CF4 layer is compressed and additional layers condense, while the SF6 layer is again diluted. Still, the SF6 layer retains about 90% concentration until the CF4 pressure is very close to saturation, at which point the SF6 is rapidly displaced, apparently going into dilute solution in the rapidly growing CF4 multilayer. Monte Carlo simulations are used to quantitatively relate measured frequency shifts to concentrations in the binary monolayer. PMID:26395723

  2. Solution and displacement in monolayer and multilayer binary films of SF6 and CF4 on graphite

    Science.gov (United States)

    Thomas, Petros; Grogan, Michael D. W.; Hess, George B.

    2015-09-01

    Infrared reflection absorption spectroscopy is used to study the evolution of binary physisorbed films on graphite. A predeposited monolayer of SF6 is exposed to slowly increasing pressure of CF4 at constant temperature between 80 and 113 K. Shifts in the frequencies of the dominant vibrational mode of each species due to resonant dipole-dipole coupling serve as proxies for the areal density of each species in the monolayer. If the initial SF6 film is far below saturation (coexistence with bulk solid), the SF6 can be largely displaced by continuous solution of CF4. However, if the initial SF6 layer is at or near saturation, a layer of CF4 condenses on top at a well defined CF4 pressure after only 2%-3% dilution of the SF6 layer. Simultaneously, most of the dissolved CF4 is withdrawn from the SF6 layer. With further increase in CF4 pressure, the CF4 layer is compressed and additional layers condense, while the SF6 layer is again diluted. Still, the SF6 layer retains about 90% concentration until the CF4 pressure is very close to saturation, at which point the SF6 is rapidly displaced, apparently going into dilute solution in the rapidly growing CF4 multilayer. Monte Carlo simulations are used to quantitatively relate measured frequency shifts to concentrations in the binary monolayer.

  3. Divalent and trivalent gas-phase coordination complexes of californium: evaluating the stability of Cf(ii).

    Science.gov (United States)

    Dau, Phuong D; Shuh, David K; Sturzbecher-Hoehne, Manuel; Abergel, Rebecca J; Gibson, John K

    2016-08-01

    The divalent oxidation state is increasingly stable relative to the trivalent state for the later actinide elements, with californium the first actinide to exhibit divalent chemistry under moderate conditions. Although there is evidence for divalent Cf in solution and solid compounds, there are no reports of discrete complexes in which Cf(II) is coordinated by anionic ligands. Described here is the divalent Cf methanesulfinate coordination complex, Cf(II)(CH3SO2)3(-), prepared in the gas phase by reductive elimination of CH3SO2 from Cf(III)(CH3SO2)4(-). Comparison with synthesis of the corresponding Sm and Cm complexes reveals reduction of Cf(III) and Sm(III), and no evidence for reduction of Cm(III). This reflects the comparative 3+/2+ reduction potentials: Cf(3+) (-1.60 V) ≈ Sm(3+) (-1.55 V) ≫ Cm(3+) (-3.7 V). Association of O2 to the divalent complexes is attributed to formation of superoxides, with recovery of the trivalent oxidation state. The new gas-phase chemistry of californium, now the heaviest element to have been studied in this manner, provides evidence for Cf(II) coordination complexes and similar chemistry of Cf and Sm. PMID:27424652

  4. Numerical simulation of evolution features of the atmospheric-pressure CF4 plasma generated by the pulsed dielectric barrier discharge

    Science.gov (United States)

    Pan, Jie; Li, Li; Chen, Bo; Song, Yuzhi; Zhao, Yuefeng; Xiu, Xianwu

    2016-06-01

    The atmospheric-pressure CF4 plasma has the high application potential in the field of semiconductor fabrication since it can combine the excellent capability for the CF4 plasma etching with the easy atmospheric-pressure operation. In this work, the fluid model has been carried out to numerically research evolution features of the atmospheric-pressure CF4 plasma generated by the pulsed dielectric barrier discharge. The computational results show that the averaged electron temperature dramatically increases during the rising and the falling phases of the applied voltage pulse, and then swiftly decreases. The discharge current density has the waveform of two bipolar short pulses. The electrons and CF3 + ions form the cathode sheath at the discharge duration. However, the CF3 - and F- negative ions take the place of the electrons to sustain the cathode sheath of the CF4 discharge plasma at the time interval between the two bipolar discharge pulses. During the time interval of the two adjacent applied voltage pulses the discharge region is the quasi-neutral plasma region, and meanwhile CF2 + and CF3 - are the dominated charged species. Moreover, F and CF3 maintain the relatively stable high densities and uniform axial distributions during the whole period of the applied voltage.

  5. Final Technical Report for grant entitled "New Horizons in C-F Activation by Main Group Electrophiles"

    Energy Technology Data Exchange (ETDEWEB)

    Ozerov, Oleg V [Texas A& M University; Ozerov, Oleg V.

    2014-01-16

    We became interested in developing new methods for hydrodefluorination (HDF) and other types of C-F bond conversion in polyfluoroalkanes under mild conditions. We were attracted to an approach to C-F activation, where the key C-F cleavage proceeds by a Lewis acid abstraction of fluoride rather than a redox event. The efforts during the previous period were aimed at a) advancing the HDF reactivity with improvement in scope and catalyst longevity; b) extending C-F activation beyond HDF; c) generating insight about the elementary steps of the reaction and potential intermediates.

  6. Effects of the curing methods on the fabrication of polycarbosilane derived SiCf/SiC composite

    International Nuclear Information System (INIS)

    Silicon carbide has potential advantages for structural applications in the next generation energy system- VHTR, GFR and the fusion reactor due to its unique properties such as a good irradiation resistance and thermo-mechanical properties, less severe waste generation due to neutron activation and improved plant conversion efficiencies by higher operating temperatures. Among the several fabrication processes for SiCf/SiC composites, the polymer impregnation and pyrolysis (PIP) process is the only method derived from polymeric precursors. In the PIP process, the careful control of the oxygen content is important to avoid the property degradation at a high temperature because polymeric precursors are used as source materials of SiC ceramics. During the polymer precursor conversion process, unintended oxygen may be introduced for a cross-linking with producing the Si-O-Si bonds at the curing step. High oxygen content affects the degradation of the high temperature stability in SiC ceramics. Therefore, a decrease of the oxygen content is desirable to obtain SiC ceramics with the high temperature stability. One of the methods to reduce the oxygen content of polymer derived SiC ceramics is the irradiation curing process by gamma ray or electron beam. Polymer derived SiC ceramics with the low oxygen content prepared by the electron beam curing showed the improved thermal stability at a higher temperature. In this study, the electron beam (EB) and the thermal oxidation curing methods were applied to make SiCf/SiC composite using a polymer precursor, polycarbosilane (PCS) by the PIP process. And the evaluations of the curing effects, the pyrolysis behaviors and a high temperature stability were performed

  7. Isolation and purification of the xenon fraction of 252Cf spontaneous fission products for the production of radioactive xenon calibration standards

    International Nuclear Information System (INIS)

    Idaho National Laboratory (INL) produces 135Xe, 133mXe, 133Xe, and 131mXe standards for the calibration and testing of the collection equipment and analytical techniques used to monitor radioactive xenon emissions. At INL, xenon is produced and collected as one of several spontaneous fission products from a 252Cf source in a stagnant volume of pressurized helium. Solids are separated from gases by sintered steel filtration. Further chromatographic purification of the fission gases separates the xenon fraction for selective collection. An explanation of gas system, separation, and purification is presented. 135Xe and 133Xe activity ratio adjustments are explained. (author)

  8. Cf/ZrC-SiC Composites Prepared by PIP with RMI%先驱体浸渍裂解结合反应熔渗法制备Cf/ZrC-SiC复合材料

    Institute of Scientific and Technical Information of China (English)

    蒋进明; 王松; 李伟

    2013-01-01

    以先驱体浸渍裂解结合反应熔渗工艺将Cf/C-SiC材料内部富余的自由碳相转变为ZrC超高温陶瓷,制备了Cf/ZrC-SiC复合材料.对Cf/C-SiC基材的孔隙进行了设计,利用XRD和SEM分析了Cf/ZrC-SiC复合材料的微观结构和物相组成.结果表明:采用PIP法可制备具有理想孔隙率的Cf/C-SiC基材;1800℃熔渗Zr-Si合金反应制得的Cf/ZrC-SiC材料主要由SiC和ZrC相组成;高温条件下熔融金属与基体反应的同时,还会侵蚀碳纤维.热解碳涂层能保护纤维.%Cf/ZrC-SiC composite was prepared by PIP with RMI through the conversion carbon of Cf/C-SiC into ZrC phase.The open porosity of Cf/C-SiC was designed, and the component and microstructure of the Cf/ZrC-SiC composite were characterized.The results show that the ideal open porosity of Cf/C-SiC could be obtained by PIP process, and the main compositions C/ZrC-SiC composites, which prepared by heating Zr-Si alloy to 1800 ℃, were ZrC and SiC phase.The reaction between melt and fibre may cause the degradation of carbon fibre.And carbon fibre can be keep from being damaged by PyC coating.

  9. 76 FR 68634 - Airworthiness Directives; General Electric Company (GE) CF6 Turbofan Engines

    Science.gov (United States)

    2011-11-07

    ...-14650 (71 FR 34807, June 16, 2006). Applicability (c) This AD applies to General Electric (GE) CF6-45A...) to amend 14 CFR part 39 to supersede AD 2006-12-24, amendment 39-14650 (71 FR 34807, June 16, 2006..., 2010 (75 FR 77570). That NPRM proposed to continue to require inspecting, stripping, and reapplying...

  10. Complete genome sequence of the bioleaching bacterium Leptospirillum sp. group II strain CF-1.

    Science.gov (United States)

    Ferrer, Alonso; Bunk, Boyke; Spröer, Cathrin; Biedendieck, Rebekka; Valdés, Natalia; Jahn, Martina; Jahn, Dieter; Orellana, Omar; Levicán, Gloria

    2016-03-20

    We describe the complete genome sequence of Leptospirillum sp. group II strain CF-1, an acidophilic bioleaching bacterium isolated from an acid mine drainage (AMD). This work provides data to gain insights about adaptive response of Leptospirillum spp. to the extreme conditions of bioleaching environments. PMID:26853478

  11. Remark on the prompt-fission-neutron spectrum of 252Cf

    International Nuclear Information System (INIS)

    Good resolution time-of-flight measurements show small structure in the prompt fission neutron spectrum of 252Cf that is identified with air-scattering effects. The observed high energy portion of the neutron spectrum is consistent with a Maxwellian distribution having a temperature of 1.42 MeV

  12. High-resolution CT of nontuberculous mycobacterium infection in adult CF patients: diagnostic accuracy

    International Nuclear Information System (INIS)

    To determine the diagnostic accuracy of high-resolution computed tomography (HRCT) for the detection of nontuberculous mycobacterium infection (NTM) in adult cystic fibrosis (CF) patients. Twenty-seven CF patients with sputum-culture-proven NTM (NTM+) underwent HRCT. An age, gender and spirometrically matched group of 27 CF patients without NTM (NTM-) was included as controls. Images were randomly and blindly analysed by two readers in consensus and scored using a modified Bhalla scoring system. Significant differences were seen between NTM (+) and NTM (-) patients in the severity of the bronchiectasis subscore [45 % (1.8/4) vs. 35 % (1.4/4), P = 0.029], collapse/consolidation subscore [33 % (1.3/3) vs. 15 % (0.6/3)], tree-in-bud/centrilobular nodules subscore [43 % (1.7/3) vs. 25 % (1.0/3), P = 0.002] and the total CT score [56 % (18.4/33) vs. 46 % (15.2/33), P = 0.002]. Binary logistic regression revealed BMI, peribronchial thickening, collapse/consolidation and tree-in-bud/centrilobular nodules to be predictors of NTM status (R2 = 0.43). Receiver-operator curve analysis of the regression model showed an area under the curve of 0.89, P < 0.0001. In adults with CF, seven or more bronchopulmonary segments showing tree-in-bud/centrilobular nodules on HRCT is highly suggestive of NTM colonisation. (orig.)

  13. LARGE GAMMA ANISOTROPY OBSERVED IN THE CF-252 SPONTANEOUS-FISSION PROCESS

    NARCIS (Netherlands)

    VANDERPLOEG, H; BACELAR, JC; VANDENBERG, T; IACOB, VE; JONGMAN, [No Value; VANDERWOUDE, A

    1992-01-01

    The energy spectrum and the angular dependence relative to the fission direction of photons in the energy region between 2 and 40 MeV have been measured for the spontaneous fission of Cf-252. A large anisotropy was found in the energy region 8 to 12 MeV implying that photons in this region are emitt

  14. STUDY OF THE GAMMA EMISSION PROBABILITY ACCOMPANYING THE SPONTANEOUS FISSION OF CF-252

    NARCIS (Netherlands)

    VANDERPLOEG, H; LAURENS, CR; BACELAR, JCS; BUDA, A; GAARDHOJE, JJ; VANTHOF, G; KALANTARNAYESTANAKI, N; VANDERWOUDE, A; ZELAZNY, Z

    1994-01-01

    A study of the gamma emission accompanying the spontaneous fission process of Cf-252 has been performed. The photon emission probability between 3 and 70 MeV and its angular dependence with respect to the fission direction were measured. These measurements were performed as a function of the mass as

  15. CF4 radio frequency plasma surface modification of silicone rubber for use as outdoor insulations

    International Nuclear Information System (INIS)

    For further prolonging the serve life of silicone rubber (SIR) for outdoor insulation and increasing its resistance of pollution flashover, surface modifications of SIR were carried out via CF4 capacitively coupled plasma at radio frequency (RF) power of 60, 100 and 200 W for a treatment time up to 20 min under CF4 flow rate of 20 sccm. Static contact angle measurement was employed to estimate the change of hydrophobicity of the modified SIR. The variation of the surface functional groups of the modified SIR was observed by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrum and X-ray photoelectron spectroscopy (XPS). The surface topography was observed by atom force microscopy (AFM). The results indicate that the static contact angle of SIR surface is improved from 100.7 deg. to 150.2 deg. via the CF4 plasma modification, and the super-hydrophobic surface of modified SIR, which corresponds to a static contact angle of 150.2 deg., appears at RF power of 200 W for a 5-min treatment time. According to the results, it is suggested that the formation of super-hydrophobic surface is ascribed to the co-action of the increase of roughness created by the ablation reaction of CF4 plasma and the formation of [-SiFx(CH3)2-x-O-]n (x = 1, 2) structure produced by the direct attachment of F atoms to Si

  16. Using Spirituality After an Adult CF Diagnosis: Cognitive Reframing and Adherence Motivation

    OpenAIRE

    Grossoehme, Daniel H.; RAGSDALE, JUDITH R.; Cotton, Sian; MEYERS, MELENIE A.; Clancy, John P.; Seid, Michael; JOSEPH, PATRICIA M.

    2012-01-01

    Chronic illness is a significant stressor; the majority of Americans cope utilizing spirituality. Numerous studies demonstrate links between spiritual coping and health outcomes. The purpose of this study was to determine whether persons diagnosed with cystic fibrosis (CF) as adults use spirituality to cope and influence disease management. Semi-structured interviews were completed and analyzed using grounded theory.

  17. High-resolution CT of nontuberculous mycobacterium infection in adult CF patients: diagnostic accuracy

    Energy Technology Data Exchange (ETDEWEB)

    McEvoy, Sinead; Lavelle, Lisa; Kilcoyne, Aoife; McCarthy, Colin; Dodd, Jonathan D. [St. Vincent' s University Hospital, Department of Radiology, Dublin (Ireland); DeJong, Pim A. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Loeve, Martine; Tiddens, Harm A.W.M. [Erasmus MC-Sophia Children' s Hospital, Department of Radiology, Department of Pediatric Pulmonology and Allergology, Rotterdam (Netherlands); McKone, Edward; Gallagher, Charles G. [St. Vincent' s University Hospital, Department of Respiratory Medicine and National Referral Centre for Adult Cystic Fibrosis, Dublin (Ireland)

    2012-12-15

    To determine the diagnostic accuracy of high-resolution computed tomography (HRCT) for the detection of nontuberculous mycobacterium infection (NTM) in adult cystic fibrosis (CF) patients. Twenty-seven CF patients with sputum-culture-proven NTM (NTM+) underwent HRCT. An age, gender and spirometrically matched group of 27 CF patients without NTM (NTM-) was included as controls. Images were randomly and blindly analysed by two readers in consensus and scored using a modified Bhalla scoring system. Significant differences were seen between NTM (+) and NTM (-) patients in the severity of the bronchiectasis subscore [45 % (1.8/4) vs. 35 % (1.4/4), P = 0.029], collapse/consolidation subscore [33 % (1.3/3) vs. 15 % (0.6/3)], tree-in-bud/centrilobular nodules subscore [43 % (1.7/3) vs. 25 % (1.0/3), P = 0.002] and the total CT score [56 % (18.4/33) vs. 46 % (15.2/33), P = 0.002]. Binary logistic regression revealed BMI, peribronchial thickening, collapse/consolidation and tree-in-bud/centrilobular nodules to be predictors of NTM status (R{sup 2} = 0.43). Receiver-operator curve analysis of the regression model showed an area under the curve of 0.89, P < 0.0001. In adults with CF, seven or more bronchopulmonary segments showing tree-in-bud/centrilobular nodules on HRCT is highly suggestive of NTM colonisation. (orig.)

  18. Caging of Cl atoms from photodissociation of CF2Cl2 in clusters

    Czech Academy of Sciences Publication Activity Database

    Poterya, Viktoriya; Kočišek, Jaroslav; Pysanenko, Andriy; Fárník, Michal

    2014-01-01

    Roč. 16, č. 2 (2014), s. 421-429. ISSN 1463-9076 R&D Projects: GA ČR GAP208/11/0161 EU Projects: European Commission(XE) 238671 - ICONIC Institutional support: RVO:61388955 Keywords : AR-N CLUSTERS * (HBR)(N) CLUSTERS * HYDROGEN HALIDES Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.493, year: 2014

  19. Clustering and Photochemistry of Freon CF2Cl2 on Argon and Ice Nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Poterya, Viktoriya; Kočišek, Jaroslav; Lengyel, Jozef; Svrčková, Pavla; Pysanenko, Andriy; Hollas, D.; Slavíček, Petr; Fárník, Michal

    2014-01-01

    Roč. 118, č. 26 (2014), s. 4740-4749. ISSN 1089-5639 R&D Projects: GA ČR GA14-08937S Institutional support: RVO:61388955 Keywords : Chemical reactions * nanoparticles * Chlorine Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.693, year: 2014

  20. Combination of HPLC and 252-Cf plasma desorption mass spectrometry for identifying composition of ginseng tinctures.

    Science.gov (United States)

    Elkin, Y N; Makhankov, V V; Uvarova, N L; Bondarenko, P V; Zubarev, R A; Knysh, A N

    1993-03-01

    The 252-Cf plasma desorption mass spectrometry (252-Cf PDMS) determination or confirmation of the ginsenoside saponins has been proposed to investigate the composition of high performance liquid chromatography (HPLC) peaks of ginseng tinctures and galenic preparations. That ionization technique is well suitable for the analysis of natural mixtures of these saponins. The 252-Cf PD mass spectra of standard ginsenosides Rb1, Rb2, Rc, Re, Rg1, Rd, NG-R2, Z-R1 contain the peaks of two types of ions, namely, molecular adduct ions (MAI) and aglycone ions. By mass the latter may be referred to either protopanaxadiol or protopanaxatriol. The masses of MAI and aglycone ions are determined by the carbohydrate chains. The collected HPLC fractions of P ginseng tincture can be tested for content of ginsenosides. After studying two MAI peaks from the 252-Cf PD mass spectra of the basic ginsenosides, an example of distinction between two galenic preparations from different Panax has been shown. PMID:8352021

  1. Assessment of Analytic Morphograph CF-1 manufactured by Kent Laboratory Services Ltd

    International Nuclear Information System (INIS)

    An addendum is presented covering the assessment of an Analytic Morphograph CF-1 which incorporates the design modifications which arose out of the initial assessment in the main DHSS report. The assessment, made at Booth Hall Children's Hospital, evaluated modifications including X-ray field size adjustment, improved patient supports, operator's protective screen, film screens and grid and film marking. (U.K.)

  2. Non-destructive inspection of SiCf/SiC composites structure

    International Nuclear Information System (INIS)

    Fiber reinforced ceramic matrix composite is an attractive candidate as a structural material for future fusion power plants because of their light weight, high temperature capability, high strength and toughness. Ceramic matrix composite made of silicon carbide matrix and fibers (SiCf/SiC) is promising for nuclear and fusion technology due to its excellent radiation resistance, especially exposure to high-energy particles such as neutron, proton, and alpha. However, porosity, which is mainly due to manufacturing process of the SiCf/SiC composites, is a critical issue in its application in fusion technology. Internal pores mitigate most of the outstanding properties of the SiCf/SiC composites such as thermal conductivity, high strength and radiation stability. The pores in composites are unavoidable and significantly reduce the life time and performance of the composites under harsh environments. The aim of the study is to examine the pore structure and alignment between the matrix/fiber bundles and high-temperature induced changes within the SiCf/SiC composite. By means of non-destructive cold neutron tomography (at Helmholtz Zentrum Berlin) and small angle neutron scattering (at Paul Scherrer Institute, PSI-Villigen) techniques inner microstructure of the composites have been investigated. The cold neutron tomography and small angle neutron scattering techniques have been applied in order to gain complementary information on the microstructure of the SiCf/SiC composites. After heat treatment of the composites at 1300 deg. C, 1400 deg. C and 1500 deg. C for 5 hours small angle neutron scattering (SANS) measurements have been carried out to understand the structural changes under high-temperature: pore size changes induced by high temperature. Scattering curves have revealed the changes in pore size at elevated temperatures. (author)

  3. Corrosion of Continuous Fiber Reinforced Aluminum Metal Matrix Composites (CF-AMCs)

    Science.gov (United States)

    Tiwari, Shruti

    The first objective of this research is to study the atmospheric corrosion behavior of continuous reinforced aluminum matrix composites (CF-AMCs). The materials used for this research were alumina (Al2O3) and nickel (Ni) coated carbon (C) fibers reinforced AMCs. The major focus is to identify the correlation between atmospheric parameters and the corrosion rates of CF-AMCs in the multitude of microclimates and environments in Hawai'i. The micro-structures of CF-AMCs were obtained to correlate the microstructures with their corrosion performances. Also electrochemical polarization experiments were conducted in the laboratory to explain the corrosion mechanism of CF-AMCs. In addition, CF-AMCs were exposed to seven different test sites for three exposure periods. The various climatic conditions like temperature (T), relative humidity (RH), rainfall (RF), time of wetness (TOW), chloride (Cl- ) and sulfate (SO42-) deposition rate, and pH were monitored for three exposure period. Likewise, mass losses of CF-AMCs at each test site for three exposure periods were determined. The microstructure of the CF-AMCS showed that Al/C/50f MMCs contained a Ni-rich phase in the matrix, indicating that the Ni coating on the C fiber dissolved in the matrix. The intermetallic phases obtained in Al-2wt% Cu/Al 2O3/50f-T6 MMC and Al-2wt%-T6 monolith were rich in Cu and Fe. The intermetallic phases obtained in Al 7075/Al2O3/50f-T6 MMC and Al 7075-T6 monolith also contained traces of Mg, Zn, Ni, and Si. Electrochemical polarization experiment indicated that the Al/Al 2O3/50f Al-2wt% Cu/Al2O3/50f-T6 and Al 7075/Al2O3/50f-T6 MMC showed similar corrosion trends as their respective monoliths pure Al, Al-2wt%-T6 and Al 7075-T6 in both aerated and deaerated condition. Al2O3 fiber, being an insulator, did not have a great effect on the polarization behavior of the composites. Al/C/50f MMCs corroded at a much faster rate as compared to pure Al monolith due to the galvanic effect between C and Al

  4. CF4 plasma treatment of tungsten bottom electrode of Cu/SiOx/W structure for resistive memory applications

    International Nuclear Information System (INIS)

    The effects of the CF4 plasma treatment on resistive memory devices were investigated. First, a 20-nm SiOx film was deposited on a CF4-treated W/TiN/SiO2/Si substrate using a radio-frequency magnetron sputter, and then a Cu top electrode was deposited to form a Cu/SiOx/CF4-treated W structure. The CF4 plasma treatment deposited fluorine atoms on the tungsten surface, reducing the interface thickness between the SiOx layer and tungsten electrode, and effectively stabilized the resistive switching and improved the switching dispersion. The CF4-treated sample showed good memory properties including a reliable non-volatile memory, non-destructive readout, stable switching voltages, and high resistance ratio of 105. - Highlights: • Effects of the CF4 plasma treatment on the resistive switching were studied. • CF4 plasma treatment deposited fluorine atoms on the tungsten surface. • CF4 plasma treatment reduced interface thickness and stabilized resistive switching

  5. SERCA and PMCA pumps contribute to the deregulation of Ca2+ homeostasis in human CF epithelial cells.

    Science.gov (United States)

    Philippe, Réginald; Antigny, Fabrice; Buscaglia, Paul; Norez, Caroline; Becq, Frédéric; Frieden, Maud; Mignen, Olivier

    2015-05-01

    Cystic Fibrosis (CF) disease is caused by mutations in the CFTR gene (CF transmembrane conductance regulator). F508 deletion is the most represented mutation, and F508del-CFTR is absent of plasma membrane and accumulates into the endoplasmic reticulum (ER) compartment. Using specific Ca2+ genetics cameleon probes, we showed in the human bronchial CF epithelial cell line CFBE that ER Ca2+ concentration was strongly increased compared to non-CF (16HBE) cells, and normalized by the F508del-CFTR corrector agent, VX-809. We also showed that ER F508del-CFTR retention increases SERCA (Sarcoplasmic/Reticulum Ca2+ ATPase) pump activity whereas PMCA (Plasma Membrane Ca2+ ATPase) activities were reduced in these CF cells compared to corrected CF cells (VX-809) and non-CF cells. We are showing for the first time CFTR/SERCA and CFTR/PMCA interactions that are modulated in CF cells and could explain part of Ca2+ homeostasis deregulation due to mislocalization of F508del-CFTR. Using ER or mitochondria genetics Ca2+ probes, we are showing that ER Ca2+ content, mitochondrial Ca2+ uptake, SERCA and PMCA pump, activities are strongly affected by the localization of F508del-CFTR protein. PMID:25661196

  6. Reaction Mechanisms on the Way from CHF3 to ArCF3. The Nature of the Ortho-Effect and Electronic Properties of the CF3 Group

    OpenAIRE

    Konovalov, Andrey I.

    2015-01-01

    Los compuestos que incorporan un grupo –CF3, especialmente en anillos aromáticos, son compuestos con gran demanda como building blocks para la industria agroquímica, farmacéutica y de materiales. Mientras que se ha progresado considerablemente con las trifluorometilaciones aromáticas catalizadas por cobre, sorprendentemente hay poca investigación referente a entender los mecanismos de esta reacción. En esta Tesis se desarrollan por primera vez, de manera combinada, estudios experimentales y c...

  7. Atmospheric chemistry of CF3O radicals: Reaction with H2O

    DEFF Research Database (Denmark)

    Wallington, T.J.; Hurley, M.D.; Schneider, W.F.;

    1993-01-01

    Evidence is presented that CF3O radicals react with H2O in the gas phase at 296 K to give CF3OH and OH radicals. This reaction is calculated to be exothermic by 1.7 kcal mol-I implying a surprisingly strong CF3O-H bond energy of 120 +/- 3 kcal mol-1. Results from a relative rate experimental stud...... suggest that the rate constant for the reaction of CF3O radicals with H2O lies in the range (0.2-4.0) X 10(-17) cm3 molecule-1 s-1. Implications for the atmospheric chemistry of CF3O radicals are discussed....

  8. Experimental studies on power frequency breakdown voltage of CF3I/N2 mixed gas under different electric fields

    Science.gov (United States)

    Zhang, Xiaoxing; Xiao, Song; Han, Yefei; Cressault, Yann

    2016-02-01

    To verify the feasibility of replacing SF6 by CF3I/N2, we compared their power frequency breakdown performance with the influence of gas pressure, mixing ratio, and electric field utilization coefficient. Under different electric fields and mixing ratios, the power frequency breakdown voltage of CF3I/N2 increases linearly along with gas pressure. Besides, with the rise of the electric field utilization coefficient, the linear growth rate of breakdown voltage along with gas pressure gradually rises. The sensitivity of pure CF3I to electric field is particularly high and can be improved by the addition of N2. The mixture 30% CF3I/70% N2 at 0.3 MPa could replace pure SF6 in equipment requiring a low insulation, but the gas pressure or the content of CF3I need to be increased for higher insulation requirements.

  9. Separation of 248Cm (III) from 252Cf (III) and its use in time resolved fluorescence spectroscopic (TRFS) studies

    International Nuclear Information System (INIS)

    The present report gives a description of the methodology for the separation of 248Cm(III) from decayed 252Cf (III) waste solution. The waste solution was first assayed for 252Cf content by neutron counting using a neutron well coincidence counter. The sample was subjected to the chemical separation of 248Cm (III) from 252Cf (III) following anion and cation exchange chromatography. The alpha spectrum of the separated curium fraction showed peaks due to 246Cm and 248Cm while the corresponding alpha spectrum of californium fraction showed 249,250,251,252Cf. The gamma ray abundances of 249Cf were determined with respect to its gamma rays of 387 keV and the data agreed well with that in literature. Separated Cm(III) was further characterized by recording its time resolved fluorescence spectrum (TRFS) in aqueous medium. (author)

  10. Chloroform Cometabolism by Butane-Grown CF8, Pseudomonas butanovora, and Mycobacterium vaccae JOB5 and Methane-Grown Methylosinus trichosporium OB3b

    OpenAIRE

    Hamamura, N.; Page, C.; Long, T; Semprini, L; Arp, D J

    1997-01-01

    Chloroform (CF) degradation by a butane-grown enrichment culture, CF8, was compared to that by butane-grown Pseudomonas butanovora and Mycobacterium vaccae JOB5 and to that by a known CF degrader, Methylosinus trichosporium OB3b. All three butane-grown bacteria were able to degrade CF at rates comparable to that of M. trichosporium. CF degradation by all four bacteria required O(inf2). Butane inhibited CF degradation by the butane-grown bacteria, suggesting that butane monooxygenase is respon...

  11. Ecological consequence of the introduction of the polychaete Marenzelleria cf. viridis into a shallow-water biotope of the northern Baltic Sea

    Science.gov (United States)

    Kotta, Jonne; Orav, Helen; Sandberg-Kilpi, Eva

    2001-12-01

    Effects of the North American polychaete Marenzelleria cf. viridis on a simple shallow-water benthic community of the northern Baltic Sea were studied in a field experiment combining natural densities of dominating macrofaunal species. The presence of M. cf. viridis increased benthic production (chlorophyll a) and reduced the survival of the native polychaete Nereis diversicolor. Adult Macoma balthica caused a significant mortality on M. cf. viridis whereas adult Cerastoderma glaucum had no effect on M. cf. viridis. We suggest that the competitive interactions between M. cf. viridis and M. balthica are a possible key factor determining the distribution pattern of M. cf. viridis in the Baltic Sea.

  12. Novel Mutations Detected in Avirulence Genes Overcoming Tomato Cf Resistance Genes in Isolates of a Japanese Population of Cladosporium fulvum.

    Directory of Open Access Journals (Sweden)

    Yuichiro Iida

    Full Text Available Leaf mold of tomato is caused by the biotrophic fungus Cladosporium fulvum which complies with the gene-for-gene system. The disease was first reported in Japan in the 1920s and has since been frequently observed. Initially only race 0 isolates were reported, but since the consecutive introduction of resistance genes Cf-2, Cf-4, Cf-5 and Cf-9 new races have evolved. Here we first determined the virulence spectrum of 133 C. fulvum isolates collected from 22 prefectures in Japan, and subsequently sequenced the avirulence (Avr genes Avr2, Avr4, Avr4E, Avr5 and Avr9 to determine the molecular basis of overcoming Cf genes. Twelve races of C. fulvum with a different virulence spectrum were identified, of which races 9, 2.9, 4.9, 4.5.9 and 4.9.11 occur only in Japan. The Avr genes in many of these races contain unique mutations not observed in races identified elsewhere in the world including (i frameshift mutations and (ii transposon insertions in Avr2, (iii point mutations in Avr4 and Avr4E, and (iv deletions of Avr4E, Avr5 and Avr9. New races have developed by selection pressure imposed by consecutive introductions of Cf-2, Cf-4, Cf-5 and Cf-9 genes in commercially grown tomato cultivars. Our study shows that molecular variations to adapt to different Cf genes in an isolated C. fulvum population in Japan are novel but overall follow similar patterns as those observed in populations from other parts of the world. Implications for breeding of more durable C. fulvum resistant varieties are discussed.

  13. CF102 an A3 adenosine receptor agonist mediates anti-tumor and anti-inflammatory effects in the liver.

    Science.gov (United States)

    Cohen, S; Stemmer, S M; Zozulya, G; Ochaion, A; Patoka, R; Barer, F; Bar-Yehuda, S; Rath-Wolfson, L; Jacobson, K A; Fishman, P

    2011-09-01

    The Gi protein-associated A(3) adenosine receptor (A(3) AR) is a member of the adenosine receptor family. Selective agonists at the A(3) AR, such as CF101 and CF102 were found to induce anti-inflammatory and anti-cancer effects. In this study, we examined the differential effect of CF102 in pathological conditions of the liver. The anti-inflammatory protective effect of CF101 was tested in a model of liver inflammation induced by Concanavalin A (Con. A) and the anti-cancer effect of CF102 was examined in vitro and in a xenograft animal model utilizing Hep-3B hepatocellular carcinoma (HCC) cells. The mechanism of action was explored by following the expression levels of key signaling proteins in the inflamed and tumor liver tissues, utilizing Western blot (WB) analysis. In the liver inflammation model, CF102 (100 µg/kg) markedly reduced the secretion of serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase in comparison to the vehicle-treated group. Mechanistically, CF102 treatment decreased the expression level of phosphorylated glycogen synthase kinase-3β, NF-κB, and TNF-α and prevented apoptosis in the liver. This was demonstrated by decreased expression levels of Fas receptor (FasR) and of the pro-apoptotic proteins Bax and Bad in liver tissues. In addition, CF102-induced apoptosis of Hep-3B cells both in vitro and in vivo via de-regulation of the PI3K-NF-κB signaling pathway, resulting in up-regulation of pro-apoptotic proteins. Taken together, CF102 acts as a protective agent in liver inflammation and inhibits HCC tumor growth. These results suggest that CF102 through its differential effect is a potential drug candidate to treat various pathological liver conditions. PMID:21660967

  14. Production, distribution and applications of californium-252 neutron sources

    International Nuclear Information System (INIS)

    The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-yr half-life. A source the size of a person's little finger can emit up to 1011 neutrons s-1. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement and minerals, as well as for detection and identification of explosives, land mines and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 yr of experience and by US Bureau of Mines tests of source survivability during explosions. The production and distribution center for the US Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells 252Cf to commercial reencapsulators domestically and internationally. Sealed 252Cf sources are also available for loan to agencies and subcontractors of the US government and to universities for educational, research and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of 252Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments and irradiation of rice to induce genetic mutations

  15. Production, distribution and applications of californium-252 neutron sources.

    Science.gov (United States)

    Martin, R C; Knauer, J B; Balo, P A

    2000-01-01

    The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-yr half-life. A source the size of a person's little finger can emit up to 10(11) neutrons s(-1). Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement and minerals, as well as for detection and identification of explosives, land mines and unexploded military ordinance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 yr of experience and by US Bureau of Mines tests of source survivability during explosions. The production and distribution center for the US Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells 252Cf to commercial reencapsulators domestically and internationally. Sealed 252Cf sources are also available for loan to agencies and subcontractors of the US government and to universities for educational, research and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of 252Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments and irradiation of rice to induce genetic mutations. PMID:11003521

  16. Ab initio full-potential study of mechanical properties and magnetic phase stability of californium monopnictides (CfN and CfP)

    Science.gov (United States)

    Amari, S.; Bouhafs, B.

    2016-09-01

    Based on the first-principles methods, the structural, elastic, electronic, properties and magnetic ordering of californium monopnictides CfX (X = P) have been studied using the full-potential augmented plane wave plus local orbitals (FP-L/APW + lo) method within the framework of density functional theory (DFT). The electronic exchange correlation energy is described by generalized gradient approximation GGA and GGA+U (U is the Hubbard correction). The GGA+U method is applied to the rare-earth 5f states. We have calculated the lattice parameters, bulk modulii and the first pressure derivatives of the bulk modulii. The elastic properties of the studied compounds are only investigated in the most stable calculated phase. In order to gain further information, we have calculated Young's modulus, shear modulus, anisotropy factor and Kleinman parameter by the aid of the calculated elastic constants. The results mainly show that californium monopnictides CfX (X = P) have an antiferromagnetic spin ordering. Density of states (DOS) and charge densities for both compounds are also computed in the NaCl (B1) structure.

  17. Bk and Cf chromatographic separation and ²⁴⁹Bk/²⁴⁸Cm and ²⁴⁹Cf/²⁴⁸Cm elemental ratios determination by inductively coupled plasma quadrupole mass spectrometry.

    Science.gov (United States)

    Gourgiotis, A; Isnard, H; Nonell, A; Aubert, M; Stadelmann, G; Dupont, E; AlMahamid, I; Tiang, G; Rao, L; Lukens, W; Cassette, P; Panebianco, S; Letourneau, A; Chartier, F

    2013-03-15

    The French Atomic Energy Commission has carried out several experiments for the study of minor-actinide transmutation processes in high intensity thermal neutron flux. In this context a Cm sample enriched in (248)Cm (∼97%) was irradiated in a thermal neutron flux at the High Flux Reactor (HFR) of the Laue-Langevin Institute (ILL). The precise and accurate determination of Cf isotope ratios and of (249)Bk/(248)Cm and (249)Cf/(248)Cm elemental ratios in the (248)Cm irradiated sample is crucial for the calculation of actinide neutron capture cross-sections. This work describes an analytical procedure for the separation and the isotope ratio measurement of Bk and Cf in the irradiated sample. The Bk and Cf separation is based on a lanthanides separation protocol previously developed by the laboratory. Well-defined retention times for Bk and Cf were obtained by coupling the Ionic Chromatography (IC) with an ICP-QMS. All conditions of element separation by IC and the different steps of the analytical protocol in order to obtain the isotopic and elemental ratios are presented. Relative uncertainties of Cf isotopic ratios range from 0.3% to 0.5% and the uncertainty of the (249)Bk/(248)Cm and (249)Cf/(248)Cm elemental ratios are respectively 6.1% and 3.2%. This level of uncertainty for both isotopic and elemental ratios is in perfect agreement with the requirement for transmutation studies. PMID:23598093

  18. 双分子水和氨气催化CF3OH分子裂解的理论研究%Theoretical Study on Decomposition of CF3OH Catalyzed by Water Dimer and Ammonia

    Institute of Scientific and Technical Information of China (English)

    龙波; 谭兴凤; 隆正文; 任达森; 张为俊

    2011-01-01

    The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atmosphere due to the high activated energy of 88.7 k J/mol at the G3 level of theory. However, the computed results predict that the barrier for unimolecular decomposition of CF3OH is decreased to 25.1 k J/mol from 188.7 k J/mol with the aid of NH3 at the G3 level of theory, which shows that the ammonia play a strong catalytic effect on the split of CF3OH. In addition, the calculated rate constants show that the decomposition of CF3OH by NH3 is faster than those of H2Oand the water dimmer by 109 and 105 times respectively. The rate constants combined with the corresponding concentrations of these species demonstrate that the reaction CF3 OH with NH3 via TS4 is of great importance for the decomposition of CF3OH in the atmosphere.

  19. Equivalent properties of single event burnout induced by different sources

    Institute of Scientific and Technical Information of China (English)

    YANG Shi-Yu; CAO Zhou; DA Dao-An; XUE Yu-Xiong

    2009-01-01

    The experimental results of single event burnout induced by heavy ions and 252Cf fission fragments in power MOSFET devices have been investigated. It is concluded that the characteristics of single event burnout induced by 252Cf fission fragments is consistent to that in heavy ions. The power MOSFET in the "turn-off" state is more susceptible to single event burnout than it is in the "turn-on" state. The thresholds of the drain-source voltage for single event burnout induced by 173 MeV bromine ions and 252Cf fission fragments are close to each other, and the burnout cross section is sensitive to variation of the drain-source voltage above the threshold of single event burnout. In addition, the current waveforms of single event burnouts induced by different sources are similar. Different power MOSFET devices may have different probabilities for the occurrence of single event burnout.

  20. Equivalent properties of single event burnout induced by different sources

    International Nuclear Information System (INIS)

    The experimental results of single event burnout induced by heavy ions and 252Cf fission fragments in power MOSFET devices have been investigated. It is concluded that the characteristics of single event burnout induced by 252Cf fission fragments is consistent to that in heavy ions. The power MOSFET in the 'turn-off' state is more susceptible to single event burnout than it is in the 'turn-on' state. The thresholds of the drain-source voltage for single event burnout induced by 173 MeV bromine ions and 252Cf fission fragments are close to each other, and the burnout cross section is sensitive to variation of the drain-source voltage above the threshold of single event burnout. In addition, the current waveforms of single event burnouts induced by different sources are similar. Different power MOSFET devices may have different probabilities for the occurrence of single event burnout. (authors)

  1. Validation of IRDFF in 252Cf Standard and IRDF-2002 Reference Neutron Fields

    Science.gov (United States)

    Simakov, Stanislav; Capote, Roberto; Greenwood, Lawrence; Griffin, Patrick; Kahler, Albert; Pronyaev, Vladimir; Trkov, Andrej; Zolotarev, Konstantin

    2016-02-01

    The results of validation of the latest release of International Reactor Dosimetry and Fusion File, IRDFF-1.03, in the standard 252Cf(s.f.) and reference 235U(nth,f) neutron benchmark fields are presented. The spectrum-averaged cross sections were shown to confirm IRDFF-1.03 in the 252Cf standard spontaneous fission spectrum; that was not the case for the current recommended spectra for 235U(nth,f). IRDFF was also validated in the spectra of the research reactor facilities ISNF, Sigma-Sigma and YAYOI, which are available in the IRDF-2002 collection. The ISNF facility was re-simulated to remove unphysical oscillations in the spectrum. IRDFF-1.03 was shown to reproduce reasonably well the spectrum-averaged data measured in these fields except for the case of YAYOI.

  2. Ten-year cures of gynecologic tumors with Cf-252 neutron brachytherapy

    International Nuclear Information System (INIS)

    In 1976, Cf-252 was a novel and clinically untested fast-neutron-emitting radioisotope that had been proposed for neutron brachytherapy (NT). About 20 primary tumors had been treated; recurrences had been used to estimate a clinical RBE. Clinical trials at the University of Kentucky treated advanced cervical tumors with intracavitary Cf-252 NT with whole-pelvis photon radiation (50-60 Gy). Local control and up to 10-year survivals were achieved without significant side effects or secondary neoplasms (eg, hematologic malignancies). Treatments were done on an outpatient basis, were much shorter, were better tolerated by medically ill, bleeding, infected, or morbidly obese patients, and produced quicker tumor response with greatly reduced costs. Long-term outcome will be reviewed

  3. Direct Measurement of the Bubble Nucleation Energy Threshold in a CF3I Bubble Chamber

    CERN Document Server

    Behnke, E; Brice, S J; Broemmelsiek, D; Collar, J I; Cooper, P S; Crisler, M; Dahl, C E; Fustin, D; Hall, J; Harnish, C; Levine, I; Lippincott, W H; Moan, T; Nania, T; Neilson, R; Ramberg, E; Robinson, A E; Sonnenschein, A; Vázquez-Jáuregui, E; Rivera, R A; Uplegger, L

    2013-01-01

    We have directly measured the energy threshold and efficiency for bubble nucleation from iodine recoils in a CF3I bubble chamber in the energy range of interest for a dark matter search. These interactions cannot be probed by standard neutron calibration methods, so we develop a new technique by observing the elastic scattering of 12 GeV/c negative pions. The pions are tracked with a silicon pixel telescope and the reconstructed scattering angle provides a measure of the nuclear recoil kinetic energy. The bubble chamber was operated with a nominal threshold of (13.6+-0.6) keV. Interpretation of the results depends on the response to fluorine and carbon recoils, but in general we find agreement with the predictions of the classical bubble nucleation theory. This measurement confirms the applicability of CF3I as a target for spin-independent dark matter interactions and represents a novel technique for calibration of superheated fluid detectors.

  4. CT of the paranasal sinuses is not a valid indicator for sinus surgery in CF patients

    DEFF Research Database (Denmark)

    Rasmussen, Jacob; Aanæs, Kasper; Norling, Rikke; Nielsen, Kim G; Johansen, Helle Krogh; von Buchwald, Christian

    2012-01-01

    BACKGROUND: No guidelines comprise when or to what extent sinus surgery should be done in patients with cystic fibrosis (CF) or how a CT scan of the paranasal sinuses should influence the decision. Symptoms of rhinosinusitis and/or eradication of pathogenic bacteria from the sinuses are reasons for...... was no significant correlation between the CT score and detection of pus, pathogenic bacteria or symptoms. Pus and pathogenic bacteria were found in several cases without sinus opacification on the CT scan. Non pathogenic and sterile cultures were also found in sinuses with opacification. CONCLUSIONS...... sinus surgery. METHODS: In this observational cross sectional study, 55 CF cases had their preoperative CT scans scored according to the Lund Mackay- and the Nair-system. Correlations between the CT scans, symptoms, surgical findings and cultures obtained during sinus surgery were made. RESULTS: There...

  5. Prediction of partial discharge and breakdown voltages in CF4 for arbitrary electrode geometries

    International Nuclear Information System (INIS)

    In literature a model was described for the simulation of the breakdown behaviour of SF6. As input parameters, results from swarm experiments—the critical field strength and the effective ionization coefficient—and thermodynamic properties are sufficient. Recently it was shown that it is possible to transfer this model to another strongly attaching gas. In this contribution the model is applied to tetrafluoromethane (CF4), which has a smaller critical field strength and is less attaching than SF6. Furthermore, the breakdown field strengths of alternating and lightning impulse voltages of different field configurations—from homogeneous to inhomogeneous fields—are predicted for CF4. A comparison to experimental results from the literature shows good agreement. Thus, the model is applicable not only to predict partial discharges and breakdown voltages in strongly attaching gases but also to gases less attaching than SF6. (paper)

  6. The CfAO's Astronomy Course in COSMOS: Curriculum Design, Rationale, and Application

    CERN Document Server

    Cooksey, Kathy L; Porter, Jason; Raschke, Lynne; Severson, Scott; Hinkley, Sasha

    2010-01-01

    From 2001 to 2007, COSMOS provided a teaching and outreach venue for the Center for Adaptive Optics Professional Development Program (CfAO PDP). COSMOS is a four-week residential mathematics and science summer program for high-school students organized by the University of California on four of its campuses. Two topical science courses comprised each COSMOS cluster. An astronomy course has always formed a basis for the CfAO PDP-affiliated cluster. The course included a variety of pedagogical techniques to address a diversity of learners and goals. We outline the astronomy course---lectures, activities, etc.---and provide the rationale for what was taught, how it was aught, and when it was taught.

  7. Etching of anode wire deposits with CF4/isobutane (80:20) avalanches

    International Nuclear Information System (INIS)

    An ionization exposure of 0.5 C per cm of wire in a gas mixture of CF4/isobutane (80:20) is shown to reverse anode wire damage in single-wire chambers. Several chambers aged in argon/ethane (50:50) and argon/ethane/ethanol (50:50:0.2) and having pulse height reduction of 25-30% have recovered pulse heights and currents to greater than 98% of their initial values. Inspection of the anode wires indicates that the thick deposits caused by the exposure in argon/ethane have been removed. Auger electron spectroscopy reveals only a thin residual layer containing primarily carbon and oxygen. This etching ability of CF4/isobutane (80:20) avalanches may explain the extremely good ageing characteristics previously reported for this mixture. (orig.)

  8. Validation of IRDFF in 252Cf Standard and IRDF-2002 Reference Neutron Fields

    Directory of Open Access Journals (Sweden)

    Simakov Stanislav

    2016-01-01

    Full Text Available The results of validation of the latest release of International Reactor Dosimetry and Fusion File, IRDFF-1.03, in the standard 252Cf(s.f. and reference 235U(nth,f neutron benchmark fields are presented. The spectrum-averaged cross sections were shown to confirm IRDFF-1.03 in the 252Cf standard spontaneous fission spectrum; that was not the case for the current recommended spectra for 235U(nth,f. IRDFF was also validated in the spectra of the research reactor facilities ISNF, Sigma-Sigma and YAYOI, which are available in the IRDF-2002 collection. The ISNF facility was re-simulated to remove unphysical oscillations in the spectrum. IRDFF-1.03 was shown to reproduce reasonably well the spectrum-averaged data measured in these fields except for the case of YAYOI.

  9. Real dimensional simulation of silicon etching in CF4 + O2 plasma

    International Nuclear Information System (INIS)

    The two-dimensional modeling of the etching of silicon in CF4+O2 plasma is considered. The profiles of etched trenches at real dimensions are calculated as a function of mask dimensions, concentrations of chemically active and non-active plasma components and ion bombardment parameters. The chemical composition of the CF4+O2 plasma is calculated, and the one-dimensional plasmochemical etching (PCE) of silicon in the plasma is investigated to achieve the goal. It was found that for O2 content in feed greater than 20%, the etching anisotropy increases, whereas the aspect ratio approaches a steady-state value. The etching anisotropy is achieved due to the formation of SiO2 on the sidewalls and the decrease of concentration of fluorine atoms in the plasma

  10. Characteristics of elastic wave generated by wear and friction of SiCf/SiC composites

    International Nuclear Information System (INIS)

    The wear characteristics of SiCf/SiC composites were evaluated according to the alignment direction of the fibers, and the elastic wave-generated friction was detected and analyzed in wearing. The friction coefficient and wear loss were similar in the longitudinal and the transverse direction of the fibers. However, these values were lower in the vertical direction of the fibers because of the brittle nature of the fiber. The friction coefficient and the wear loss were directly proportional to each other. The dominant frequencies were 58.6 kHz for monolithic SiC and 117.2 and 136.7 kHz for SiCf/SiC composites, respectively.

  11. Stress Distribution of CF/EP Laminated Composites under Supercritical Conditions

    Directory of Open Access Journals (Sweden)

    Haihong Huang

    2015-01-01

    Full Text Available Enormous amounts of wastes have been produced due to extensive use of carbon fiber/epoxy resin (CF/EP composites. The fact that the supercritical fluid can be used to recycle these composites efficiently has attracted widespread concerns. A three-dimensional model of CF/EP laminates considering the interfacial layers was established. The internal stress distribution of laminates was simulated based on a heat transfer model; and the change of shear stress with supercritical temperature and pressure was investigated. The results show that the shear stress concentration was located in the interfacial layers; the maximum shear stress can be expressed by a curve of convex parabola to the temperature; and the most serious damage occurred in interfacial layers when temperature approached the glass-transition temperature of resin.

  12. Clusters in true ternary fission in the 252Cf (Sf) reaction

    International Nuclear Information System (INIS)

    In the paper effect of the formation of clusters on production of the true ternary fission at simultaneous fission of 2'52Cf is investigated. Unlike conventional ternary fission with the emission of the alpha particle and binary fission, in true ternary fission reaction products are observed with the comparable masses and charges. By studying the potential energy surface calculated for the ternary system before splitting, charge and mass distributions of the nascent products at the spontaneous fission of 252Cf are estimated. Probabilities of the true ternary fission products will be greater where the potential energy surface has minima deeper. Results showed that the products of true ternary fission with magical numbers 20, 28, 50 and 82 for protons and neutrons are formed with a high probability. (authors)

  13. Effects of 252Cf neutrons, transmitted through an iron block on human lymphocyte chromosome

    International Nuclear Information System (INIS)

    Chromosome aberration of human peripheral blood lymphocytes exposed to californium-252 (252Cf) neutrons transmitted through a 15 cm thick iron block was analysed. The spectrum of the filtered neutrons ranged from 0.1 to 2MeV with a peak at 0.7 MeV, simulating the Hiroshima atomic bomb neutron spectrum as shown in the Dosimetry System 1986 (DS86). Chromosome aberration frequencies after exposure to filtered and unfiltered 252Cf radiation were compared. Acentric ring chromosomes were significantly increased (p 0.1). The relative biological effectiveness (RBE) of the neutrons with respect to the formation of dicentrics and centric rings was 10.9 and 12.3 in the filtered and unfiltered conditions respectively, but the difference was not statistically significant. These results provide useful information for the re-evaluation of the biological effect of the Hiroshima atomic bomb radiations. (Author)

  14. Constructing a Catalytic Cycle for C-F to C-X (X = O, S, N) Bond Transformation Based on Gold-Mediated Ligand Nucleophilic Attack.

    Science.gov (United States)

    Hu, Ji-Yun; Zhang, Jing; Wang, Gao-Xiang; Sun, Hao-Ling; Zhang, Jun-Long

    2016-03-01

    A tricoordinated gold(I) chloride complex, tBuXantphosAuCl, supported by a sterically bulky 9,9-dimethyl-4,5-bis(di-tert-butylphosphino)xanthene ligand (tBuXantphos) was synthesized. This complex features a remarkably longer Au-Cl bond length [2.632(1) Å] than bicoordinated linear gold complexes (2.27-2.30 Å) and tricoordinated XantphosAuCl [2.462(1) Å]. Single-crystal X-ray diffraction analysis of a cocrystal of tBuXantphosAuCl and pentafluoronitrobenzene (PFNB) and UV-vis spectroscopic titration experiments revealed the existence of an anion-π interaction between the Cl anion ligand and PFNB. Stoichiometric reaction between PFNB and tBuXantphosAuOtBu, after replacement of Cl by a more nucleophilic tBuO anion ligand, showed higher reactivity and para selectivity in the transformation of C-F to C-OtBu bond, distinctively different from that when only KOtBu was used (ortho selectivity) under the identical condition. Mechanistic studies including density functional theory calculations suggested a gold-mediated nucleophilic ligand attack of the C-F bond pathway via an SNAr process. On the basis of these results, using trimethylsilyl derivatives TMS-X (X = OMe, SEt, NEt2) as the nucleophilic ligand source and the fluorine acceptor, catalytic transformation of the C-F bond of aromatic substrates to the C-X (X = O, S, N) bond was achieved with tBuXantphosAuCl as the catalyst (up to 20 turnover numbers). PMID:26872251

  15. Ab initio quantum mechanical study for the photolysis and unimolecular decomposition reactions in the atmosphere of CF3OH

    International Nuclear Information System (INIS)

    The electronic transitions from the ground state to low-lying excited states of CF3OH have been investigated using high level ab initio quantum mechanical techniques. Also the possible photo dissociation procedures of CF3OH have been considered. The highest level employed in this study is TZP CCSD(T) level of theory. The possible four low-lying excited states can result by the excitation of the lone pair electron (n) in oxygen to σ molecular orbital in C-O or O-H bond. The vertical transition (n→σ) energy is predicted to be 220.5 kcal/mol (130 nm) at TZ2P CISD level to theory. The bond dissociation energies of CF3OH to CF3O + H and CF3+OH have been predicted to be 119.5 kcal/mol 114.1 kcal/mol, respectively, at TZP CCSD level of theory. In addition, the transition state for the unimolecular decomposition of CF3OH into CF2O + HF has been examined. The activation energy and energy separation for this decomposition have been computed to be 43.6 kcal/mol and 5.0 kcal/mol including zero-point vibrational energy corrections at TZP CCSD(T) level of theory

  16. Full Space Vectors Modulation for Nine-Switch Converters Including CF & DF Modes

    DEFF Research Database (Denmark)

    Dehghan Dehnavi, Seyed Mohammad; Mohamadian, Mustafa; Andersen, Michael A. E.

    2010-01-01

    converter. As a space vector modulation for DF mode has already been proposed by authors. This paper proposes a full space vector modulation (SVM) for both CF and DF modes. Also practical methods are presented for SVM proposed. In addition a special SVM is proposed that offers minimum total harmonic...... distortion (THD) in DF mode. The performance of the proposed SVM is verified by simulation results....

  17. Macromolecule formation in low density CF4 plasmas: The influence of H2

    Science.gov (United States)

    Schabel, M. J.; Peterson, T. W.; Muscat, A. J.

    2003-02-01

    High molecular weight fluorocarbon species are regarded as important contributors to the nucleation of films and particulates in fluorocarbon plasmas. The chemical reaction mechanisms by which fluorocarbon macromolecules form within a plasma are generally unknown. To elucidate these mechanisms, experiments were conducted in a rf capacitively coupled discharge in a Gaseous Electronics Conference reference cell. The relationships between macromolecule growth and plasma pressure, power, flow rate, and the fraction of H2 in the CF4 gas feed are identified. Macromolecule growth was found to increase with increased pressure and rf power, and decreased flow rate. A set of electron-induced dissociation and radical-recombination reactions are simulated using Chemkin-Aurora, a commercially available plasma chemistry model, and are in good agreement with the experimental results of macromolecule growth. We show that a primary mechanism by which fluorocarbon macromolecules form in a plasma occurs by electron-induced dissociation of a fluoroalkane to produce a fluoroalkyl radical and a fluorine atom, followed by a three-body radical-radical recombination reaction with CF3. Hydrogen is shown to have a profound effect on this reaction sequence by reducing the gas phase atomic fluorine concentration through the formation of HF which in turn increases the CF3 concentration available to participate in the macromolecule growth process. At moderate levels of hydrogen in the feed gas (<20%), macromolecule growth is directly correlated with the fraction of hydrogen in the feed gas. At high concentrations of hydrogen, hydrofluorocarbon and hydrocarbon growth occurs in the plasma at the expense of fluorocarbon macromolecule growth. The conditions under which the formation of these species occurs is consistent with observations in the literature of dramatic reductions in silicon dioxide etching rate. The transition between the formation of fluorocarbon macromolecules and hydrocarbon

  18. Cryptocandin, a potent antimycotic from the endophytic fungus Cryptosporiopsis cf. quercina

    OpenAIRE

    Strobel, GA; Miller, RV; Martinez-Miller, C; Condron, MM; Teplow, DB; Hess, WM

    1999-01-01

    A unique lipopeptide antimycotic, termed cryptocandin, is described from Cryptosporiopsis cf. quercina, an endophytic fungus. Cryptocandin, with a molecular mass of 1079 Da, contains equimolar amounts of 3,4-dihydroxyhomotyrosine, 4-hydroxyproline, threonine, glutamine, 3-hydroxy-4-hydroxymethylproline, 4,5-dihydroxyornithine and palmitic acid. Cryptocandin is chemically related to well-known antimycotics, the echinocandins and pneumocandins, which are produced by such fungi as Zalerion arbor...

  19. Scorpion envenoming caused by Tityus cf. silvestris evolving with severe muscle spasms in the Brazilian Amazon.

    Science.gov (United States)

    Monteiro, Wuelton Marcelo; de Oliveira, Sâmella Silva; Pivoto, Guilherme; Alves, Eliane Campos; de Almeida Gonçalves Sachett, Jacqueline; Alexandre, Cleber Nunes; Fé, Nelson Ferreira; Barbosa Guerra, Maria das Graças Vale; da Silva, Iran Mendonça; Tavares, Antonio Magela; Ferreira, Luiz Carlos de Lima; Lacerda, Marcus Vinícius Guimarães

    2016-09-01

    Scorpion stings are a public health problem in the Brazilian Amazon. However, detailed clinical characterization with the proper animal identification is scarce. Here we report a confirmed case of envenoming by Tityus cf. silvestris in the Brazilian Amazon. The case evolved with generalized muscle spasms and was treated with antivenom and supportive therapy, requiring intensive care unit admission. The patient evolved favourably and was discharged after 9 days of hospitalization. PMID:27368713

  20. Theoretical study of lanthanide mono cation-mediated C-F bond activation

    International Nuclear Information System (INIS)

    Graphical abstract: Performing density functional B3LYP and multi-reference CASPT2 calculations, we found that all Ln+ reactions can be classified into one of two different reaction mechanisms, 'harpoon-like' and 'insertion-elimination', which were experimentally proposed by Cohrnel et al. and Konayagi et al., respectively. The two mechanisms have been proposed exclusive to each other. Our results show that both reaction mechanisms are possible in Ln+ reaction systems. Research highlights: → The lanthanide mono-cations (Ln+) activate C-F bond. → The C-F bond activation reactions with Ln+ proceed with two mechanisms, harpoon-like and insertion-elimination mechanisms. → Gd+ shows extremely high C-F bond activation ability. - Abstract: The potential energy surface corresponding to the reaction of lanthanide mono-cations (Ln+; Ln = Ce-Yb) with CH3F has been investigated using density functional theory calculations. In the initial step of the C-F activation reaction, Ln+ directly coordinates to the F atom of CH3F, and forms same [Ln...F...CH3]+ type transition state structures with an accompanying electron-transfer from the Ln+ to the F atom. Performing intrinsic reaction coordinate calculations from the transition states, we found that all Ln+ reactions can be classified into one of two different reaction mechanisms, 'harpoon-like' and 'insertion-elimination', which were experimentally proposed by Cohrnel et al. and Konayagi et al., respectively. The two mechanisms have been proposed exclusive to each other. Our results show that both reaction mechanisms are possible in Ln+ reaction systems.

  1. Assessment of Analytic Morphograph CF-1 manufactured by Kent Laboratory Services Ltd

    International Nuclear Information System (INIS)

    DHSS assessment reports, prepared by St Lawrence Hospital, Chepstow and the Hospital for Sick Children, Great Ormond Street are presented for the Analytic Morphograph CF-1. This machine converts the central principle of morphanalysis - the Fixed Relations Theory - into clinical practice by producing radiographs and photographs of the human head which are universally related in three dimensions. Both technical and clinical aspects of the equipment's performance are examined. (U.K.)

  2. First joint record of Mesopithecus and cf. Macaca in the Miocene of Europe.

    Science.gov (United States)

    Alba, David M; Delson, Eric; Carnevale, Giorgio; Colombero, Simone; Delfino, Massimo; Giuntelli, Piero; Pavia, Marco; Pavia, Giulio

    2014-02-01

    Cercopithecid fossil remains from the post-evaporitic Messinian (5.40-5.33 Ma, MN13, latest Turolian, latest Miocene) locality of Moncucco Torinese (Tertiary Piedmont Basin, NW Italy) are described. A talus is assigned to the fossil colobine Mesopithecus pentelicus, while a proximal fragment of ulna and a male lower canine are attributed to cf. Me. pentelicus. An isolated I(2) and M3 are assigned to the papionin cf. Macaca sp., and two cercopithecid phalanges are left unassigned even to the subfamily level. The record of Mesopithecus at Moncucco Torinese agrees well with the previously-known range of this species in Italy and elsewhere in Europe, whereas that of cf. Macaca constitutes only the second occurrence of macaques in the Miocene of Eurasia. Although the co-occurrence of these two genera in a single locality had been previously reported in the Pliocene, this is the first instance in which macaques are associated with the Late Miocene M. pentelicus instead of Mesopithecus monspessulanus. The record of cf. Macaca and Mesopithecus-and especially the latter's talar morphology, similar to that of extant arboreal colobines-fits well with paleoenvironmental reconstructions of Moncucco Torinese based on the associated fauna, which indicate a humid and densely-forested environment, probably with more open and drier habitats nearby. From a paleobiogeographic viewpoint, the record of Macaca at Moncucco Torinese, together with the previously reported occurrence at Almenara-Casablanca M (Spain), supports the contention that macaques dispersed from Africa into Europe during the latest Miocene (ca. 5.9-5.3 Ma) at the same time as the sea level drop associated with the Messinian Salinity Crisis. PMID:24342451

  3. Stability of 248-254^Cf isotopes against alpha and cluster radioactivity

    OpenAIRE

    Santhosh, K. P.; Biju, R. K.

    2013-01-01

    Stability of 248-254^Cf nuclei against alpha and cluster emission is studied within our Coulomb and proximity potential model (CPPM). It is found that these nuclei are stable against light clusters (except alpha particle) and instable against heavy cluster emissions. For heavy cluster emissions the daughter nuclei lead to doubly magic 208^Pb or neighbouring one. The effect of quadrapole and hexadecapole deformations of parent nuclei, daughter nuclei and emitted cluster on half lives are also ...

  4. Mechanisms and Kinetics of Reactions of the O (1D,3p) + CF3Cl System

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ In the stratosphere, CF3Cl (CFC 13) can either photodecompose or react directly with atomic oxygen to generate ozone-depleting agents such as Cl and ClO in the gas phase[1-3]. Since the 1970s, attention has been focused on the effects of these compounds on the destruction of ozone in the stratosphere and on global warming[4,5].

  5. Vacuum-UV negative photoion spectroscopy of SF5CF3

    OpenAIRE

    Simpson, M.J.; Tuckett, R. P.; Dunn, K; Hunniford, A.; Latimer, C. J.; Scully., S. W. J.

    2008-01-01

    Ion pair formation, generically described as AB \\(\\rightarrow\\) A\\(^+\\) + B\\(^-\\), from vacuum-UV photoexcitation of trifluoromethyl sulfur pentafluoride, SF\\(_5\\)CF\\(_3\\), has been studied by anion mass spectrometry using synchrotron radiation in the photon energy range 10-35 eV. The anions F\\(^-\\), F\\(_2\\)\\(^-\\) and SF\\(_X\\)\\(^-\\) (x = 1-5) are observed. With the exception of SF\\(_5^-\\), the anions observed show a linear dependence of signal with pressure, showing that they arise from ion p...

  6. Separation of Am(III), Cm(III), and Cf(III) using capillary electrophoresis

    International Nuclear Information System (INIS)

    Trivalent actinides Am(III), Cm(III), and Cf(III) were successfully separated for the first time using capillary electrophoresis in 2-hydroxyisobutyric acid/acetic acid. It was found that the ionic radius was primarily important for separation of trivalent actinides as well as lanthanides in this condition. The stability constants of the Am(III) complexes with 2-hydroxyisobutyrate were estimated using the correlations between the molar fraction ratio of lanthanides and their ionic radii. (orig.)

  7. Genetic characterization of the conjugative DNA processing system of enterococcal plasmid pCF10

    OpenAIRE

    Staddon, Jack H.; Bryan, Edward M.; Manias, Dawn A.; Chen, Yuqing; Dunny, Gary M.

    2006-01-01

    Conjugation is a major contributor to lateral gene transfer in bacteria, and pheromone-inducible conjugation systems in Enterococcus faecalis play an important role in the dissemination of antibiotic resistance and virulence in enterococci and related bacteria. We have genetically dissected the determinants of DNA processing of the enterococcal conjugative plasmid pCF10. Insertional inactivation of a predicted relaxase gene pcfG, via insertion of a splicing-deficient group II intron, severely...

  8. Additive for Low-Temperature Operation of Li-(CF)n Cells

    Science.gov (United States)

    West, William; Whitacre, Jay

    2009-01-01

    Some progress has been reported in continuing research on the use of anion-receptor compounds as electrolyte additives to increase the sustainable rates of discharge and, hence, the discharge capacities, of lithium-poly(carbon monofluoride) [Li-(CF)n, where n >1] primary electrochemical power cells. Some results of this research at a prior stage were summarized in Increasing Discharge Capacities of Li(CF)n Cells (NPO-42346), NASA Tech Briefs, Vol. 32, No. 2 (February 2008), page 37. A major difference between the present and previously reported results is that now there is some additional focus on improving performance at temperatures from ambient down to as low as 40 C. To recapitulate from the cited prior article: During the discharge of a Li-(CF)n cell, one of the electrochemical reactions causes LiF to precipitate at the cathode. LiF is almost completely insoluble in most non-aqueous solvents, including those used in the electrolyte solutions of Li- (CF)n cells. LiF is electrochemically inactive and can block the desired transport of electrons at the cathode, and, hence, the precipitation of LiF can form an ever-thickening film on the cathode that limits the rate of discharge. An anion-receptor electrolyte additive helps to increase the discharge capacity in two ways: It renders LiF somewhat soluble in the non-aqueous electrolyte solution, thereby delaying precipitation until a high concentration of LiF in solution has been reached. When precipitation occurs, it promotes the formation of large LiF grains that do not conformally coat the cathode. The net effect is to reduce the blockage caused by precipitation of LiF, thereby maintaining a greater degree of access of electrolyte to the cathode and greater electronic conductivity.

  9. Analysis of linear energy transfers and quality factors of charged particles produced by spontaneous fission neutrons from 252Cf and 244Pu in the human body

    International Nuclear Information System (INIS)

    Absorbed doses, linear energy transfers (LETs) and quality factors of secondary charged particles in organs and tissues, generated via the interactions of the spontaneous fission neutrons from. 252Cf and. 244Pu within the human body, were studied using the Particle and Heavy Ion Transport Code System (PHITS) coupled with the ICRP Reference Phantom. Both the absorbed doses and the quality factors in target organs generally decrease with increasing distance from the source organ. The analysis of LET distributions of secondary charged particles led to the identification of the relationship between LET spectra and target-source organ locations. A comparison between human body-averaged mean quality factors and fluence-averaged radiation weighting factors showed that the current numerical conventions for the radiation weighting factors of neutrons, updated in ICRP103, and the quality factors for internal exposure are valid. (authors)

  10. A new spontaneous fission mode for 252Cf: Hyperdeformation, cluster radioactivity, new levels

    International Nuclear Information System (INIS)

    Direct measurements of yields and neutron multiplicities were made for Sr-Nd, Zr-Ce, Mo-Ba, Ru-Xe, and Pd-Te from γ-ray coincidence studies in spontaneous fission of 252Cf. Strong enhancement of the 7-10 ν emission channels is seen in the Mo-Ba data. Unfolding the Mo-Ba data revealed a new fission mode associated with the enhanced ν yields with much lower total kinetic energy going by 108Mo-144Ba, 107Mo- 145Ba, and/or 106Mo-146Ba. Analysis indicates one or more of 144,145,146Ba are hyperdeformed with 3:1 axis ratio. Theoretical calculations predict a third minimum in the PES for 252Cf with β2 ∼ 0.9 and β3 ∼ 0.7. Zero neutron emission channels, a new form of cluster radioactivity, are seen in 8 and 7 correlated pairs in SF of 252Cf and 242Pu, respectively, with the odd-odd zero neutron channel yields strongly enhanced as predicted for cluster radioactivity. New level structures and isotopes include new octupole deformations, identical bands and other structures

  11. A restructuring of the CF/EDF packages for the MIDAS computer code

    International Nuclear Information System (INIS)

    The CF and EDF packages, which allow the user to define the functions of variables in a database and the usage of an external data file, have been restructured for the MIDAS computer code. MIDAS is being developed as an integrated severe accident analysis code with a user-friendly graphical user interface and a modernized data structure. To restructure the code, the data transferring methods of the current MELCOR code are modified and then partially adopted into the CF/EDF packages. The data structure of the current MELCOR code using FORTRAN77 has a difficulty in grasping the meaning of the variables as pointers are used to define their addresses. New features of FORTRAN90 make it possible to allocate the storage dynamically and to use the user-defined data type without pointers leading to an efficient memory treatment and an easy understanding of the code. Restructuring of the CF/EDF packages addressed in this paper includes a module development and subroutine modification. The verification has been done by comparing the results of the modified code with those of the existing code and the trends are almost the same to each other. Therefore the similar approach could be extended to the entire code package for code restructuring. It is expected that the code restructuring will accelerate the code's domestication thanks to a direct understanding of each variable and an easy implementation of the modified or newly developed models. (author)

  12. A restructuring of the CF/EDF packages for the MIDAS computer code

    Energy Technology Data Exchange (ETDEWEB)

    Park, S.H.; Kim, K.R.; Kim, D.H. [Korea Atomic Energy Research Inst., Yuseong, Daejon (Korea, Republic of)]. E-mail: shpark2@kaeri.re.kr; krkim@kaeri.re.kr; dhkim8@kaeri.re.kr

    2004-07-01

    The CF and EDF packages, which allow the user to define the functions of variables in a database and the usage of an external data file, have been restructured for the MIDAS computer code. MIDAS is being developed as an integrated severe accident analysis code with a user-friendly graphical user interface and a modernized data structure. To restructure the code, the data transferring methods of the current MELCOR code are modified and then partially adopted into the CF/EDF packages. The data structure of the current MELCOR code using FORTRAN77 has a difficulty in grasping the meaning of the variables as pointers are used to define their addresses. New features of FORTRAN90 make it possible to allocate the storage dynamically and to use the user-defined data type without pointers leading to an efficient memory treatment and an easy understanding of the code. Restructuring of the CF/EDF packages addressed in this paper includes a module development and subroutine modification. The verification has been done by comparing the results of the modified code with those of the existing code and the trends are almost the same to each other. Therefore the similar approach could be extended to the entire code package for code restructuring. It is expected that the code restructuring will accelerate the code's domestication thanks to a direct understanding of each variable and an easy implementation of the modified or newly developed models. (author)

  13. Cracking behavior of thermally aged and irradiated CF-8 cast austenitic stainless steel

    Science.gov (United States)

    Chen, Y.; Alexandreanu, B.; Chen, W.-Y.; Natesan, K.; Li, Z.; Yang, Y.; Rao, A. S.

    2015-11-01

    To assess the combined effect of thermal aging and neutron irradiation on the cracking behavior of CF-8 cast austenitic stainless steel, crack growth rate (CGR) and fracture toughness J-R curve tests were carried out on compact-tension specimens in high-purity water with low dissolved oxygen. Both unaged and thermally aged specimens were irradiated at ∼320 °C to 0.08 dpa. Thermal aging at 400 °C for 10,000 h apparently had no effect on the corrosion fatigue and stress corrosion cracking behavior in the test environment. The cracking susceptibility of CF-8 was not elevated significantly by neutron irradiation at 0.08 dpa. Transgranular cleavage-like cracking was the main fracture mode during the CGR tests, and a brittle morphology of delta ferrite was often seen on the fracture surfaces at the end of CGR tests. The fracture toughness J-R curve tests showed that both thermal aging and neutron irradiation can induce significant embrittlement. The loss of fracture toughness due to neutron irradiation was more pronounced in the unaged than aged specimens. After neutron irradiation, the fracture toughness values of the unaged and aged specimens were reduced to a similar level. G-phase precipitates were observed in the aged and irradiated specimens with or without prior aging. The similar microstructural changes resulting from thermal aging and irradiation suggest a common microstructural mechanism of inducing embrittlement in CF-8.

  14. Compatibility of PIP SiCf/SiC with LiPb at 700 deg. C

    International Nuclear Information System (INIS)

    Silicon carbide fiber reinforced silicon carbide composites (SiCf/SiC) are promising candidate materials for fusion applications. The compatibility of SiCf/SiC composites with liquid LiPb is one of the key issues for fusion technologies. Three-dimensional SiCf/SiC composites were fabricated by polymer infiltration and pyrolysis (PIP) process and β-SiC coating was deposited by chemical vapor deposition (CVD) process. The composites were exposed to static liquid LiPb for 500 h at 700 deg. C. The results showed that the liquid LiPb penetrated through the open pores of the cut surface of the composites and reacted with the matrix and fibers, which caused a weight change and a severe degradation of the mechanical property to the uncoated composites. As for the coated composites, the mechanical property was degraded and the weight increased because of the absorption of LiPb, although the CVD SiC coating was compatible with LiPb and protected fibers and matrix beneath.

  15. Production and investigation of thin films of metal actinides (Pu, Am, Cm, Bk, Cf)

    Science.gov (United States)

    Radchenko, V. M.; Ryabinin, M. A.; Stupin, V. A.

    2010-03-01

    Under limited availability of transplutonium metals some special techniques and methods of their production have been developed that combine the process of metal reduction from a chemical compound and preparation of a sample for examination. In this situation the evaporation and condensation of metal onto a substrate becomes the only possible technology. Thin film samples of metallic 244Cm, 248Cm and 249Bk were produced by thermal reduction of oxides with thorium followed by deposition of the metals in the form of thin layers on tantalum substrates. For the production of 249Cf metal in the form of a thin layer the method of thermal reduction of oxide with lanthanum was used. 238Pu and 239Pu samples in the form of films were prepared by direct high temperature evaporation and condensation of the metal onto a substrate. For the production of 241Am films a gram sample of plutonium-241 metal was used containing about 18 % of americium at the time of production. Thermal decomposition of Pt5Am intermetallics in vacuum was used to produce americium metal with about 80% yield. Resistivity of the metallic 249Cf film samples was found to decrease exponentially with increasing temperature. The 249Cf metal demonstrated a tendency to form preferably a DHCP structure with the sample mass increasing. An effect of high specific activity on the crystal structure of 238Pu nuclide thin layers was studied either.

  16. Production and investigation of thin films of metal actinides (Pu, Am, Cm, Bk, Cf)

    International Nuclear Information System (INIS)

    Under limited availability of transplutonium metals some special techniques and methods of their production have been developed that combine the process of metal reduction from a chemical compound and preparation of a sample for examination. In this situation the evaporation and condensation of metal onto a substrate becomes the only possible technology. Thin film samples of metallic 244Cm, 248Cm and 249Bk were produced by thermal reduction of oxides with thorium followed by deposition of the metals in the form of thin layers on tantalum substrates. For the production of 249Cf metal in the form of a thin layer the method of thermal reduction of oxide with lanthanum was used. 238Pu and 239Pu samples in the form of films were prepared by direct high temperature evaporation and condensation of the metal onto a substrate. For the production of 241Am films a gram sample of plutonium-241 metal was used containing about 18 % of americium at the time of production. Thermal decomposition of Pt5Am intermetallics in vacuum was used to produce americium metal with about 80% yield. Resistivity of the metallic 249Cf film samples was found to decrease exponentially with increasing temperature. The 249Cf metal demonstrated a tendency to form preferably a DHCP structure with the sample mass increasing. An effect of high specific activity on the crystal structure of 238Pu nuclide thin layers was studied either.

  17. Laboratory rotational ground state transitions of NH$_3$D$^+$ and CF$^+$

    CERN Document Server

    Stoffels, Alexander; Schlemmer, Stephan; Brünken, Sandra

    2016-01-01

    Aims. This paper reports accurate laboratory frequencies of the rotational ground state transitions of two astronomically relevant molecular ions, NH3D+ and CF+. Methods. Spectra in the millimeter-wave band were recorded by the method of rotational state-selective attachment of He-atoms to the molecular ions stored and cooled in a cryogenic ion trap held at 4 K. The lowest rotational transition in the A state (ortho state) of NH$_3$D$^+$ ($J_K = 1_0 - 0_0$), and the two hyperfine components of the ground state transition of CF$^+$($J = 1 - 0$) were measured with a relative precision better than $10^{-7}$. Results. For both target ions the experimental transition frequencies agree with recent observations of the same lines in different astronomical environments. In the case of NH$_3$D$^+$ the high-accuracy laboratory measurements lend support to its tentative identification in the interstellar medium. For CF$^+$ the experimentally determined hyperfine splitting confirms previous quantum-chemical calculations a...

  18. Interpreting the near-infrared spectra of the 'golden standard' Type Ia supernova 2005cf

    CERN Document Server

    Gall, E E E; Kromer, M; Sim, S A; Benetti, S; Blanc, G; Elias-Rosa, N; Hillebrandt, W

    2012-01-01

    We present nine near-infrared (NIR) spectra of supernova (SN) 2005cf at epochs from -10 d to +42 d with respect to B-band maximum, complementing the existing excellent data sets available for this prototypical Type Ia SN at other wavelengths. The spectra show a time evolution and spectral features characteristic of normal Type Ia SNe, as illustrated by a comparison with SNe 1999ee, 2002bo and 2003du. The broad-band spectral energy distribution (SED) of SN 2005cf is studied in combined ultraviolet (UV), optical and NIR spectra at five epochs between ~ 8 d before and ~ 10 d after maximum light. We also present synthetic spectra of the hydrodynamic explosion model W7, which reproduce the key properties of SN 2005cf not only at UV-optical as previously reported, but also at NIR wavelengths. From the radiative-transfer calculations we infer that fluorescence is the driving mechanism that shapes the SED of SNe Ia. In particular, the NIR part of the spectrum is almost devoid of absorption features, and instead domin...

  19. Decision Making about Risk of Infection by Young Adults with CF

    Directory of Open Access Journals (Sweden)

    Lisa Reynolds

    2013-01-01

    Full Text Available Young people with cystic fibrosis (CF are asked to avoid a number of environments associated with increased infection risk, but in practice they need to balance this with competing priorities such as building and sustaining relationships with friends and family. This study explored the process by which young people make these decisions. Mixed methods were used: a vignette study presenting choices around engaging in activities involving a degree of infection risk and a thematic analysis of participant's accounts of their decision making. The eight participants chose to engage in high risk behaviours in 59% of the choices. All participants chose to engage in at least one risky behavior, though this was less likely when the risk was significant. Thematic analysis revealed large areas of misunderstanding and lack of knowledge, leading to some potentially worrying misconceptions about the nature of infections and risk. Young people with CF are not currently making informed decisions around activities that involve increased risk of infection, and there is an urgent need for CF teams to address this in information provision.

  20. Effect of heavy ion irradiation on microstructural evolution in CF8 cast austenitic stainless steel

    Science.gov (United States)

    Chen, Wei-Ying; Li, Meimei; Kirk, Marquis A.; Baldo, Peter M.; Lian, Tiangan

    2016-04-01

    The microstructural evolution in ferrite and austenitic in cast austenitic stainless steel (CASS) CF8, as received or thermally aged at 400 °C for 10,000 h, was followed under TEM with in situ irradiation of 1 MeV Kr ions at 300 and 350 °C to a fluence of 1.9 × 1015 ions/cm2 (∼3 dpa) at the IVEM-Tandem Facility. For the unaged CF8, the irradiation-induced dislocation loops appeared at a much lower dose in the austenite than in the ferrite. At the end dose, the austenite formed a well-developed dislocation network microstructure, while the ferrite exhibited an extended dislocation structure as line segments. Compared to the unaged CF8, the aged specimen appeared to have lower rate of damage accumulation. The rate of microstructural evolution under irradiation in the ferrite was significantly lower in the aged specimen than in the unaged. This difference is attributed to the different initial microstructures in the unaged and aged specimens, which implies that thermal aging and irradiation are not independent but interconnected damage processes.

  1. Fission-Neutron Spectra of U235, Pu239 And Cf252

    International Nuclear Information System (INIS)

    Measurements of the fission neutron spectra from the neutron-induced fission of U235 and Pu239, and the spontaneous fission of Cf252, have been made. The spectra were measured with a time-of-flight technique using a plastic scintillator as the fission-neutron detector. The low energy part of the Cf252 fission-neutron spectrum (below 0.3 MeV) was also measured with a Li6 -glass detector replacing the plastic scintillator. The fissile materials were mounted in xenon-gas scintillation cham-bers. The primary neutrons were produced by a 2.5-MeV Van de Graaff accelerator with top terminal pulsing. The resolving time of the time-of-flight equipment was better than 3 ns. Results fitted to Maxwellian distributions, √Ee-E/T, are presented for neutron-induced fissions of U235 at 40 keV and 1.5 MeV of incident neutron energy and for Pu239 at 40 keV. Results are also given for the fission-neutron energy spectrum of Cf252. (author)

  2. Controlled modification of mono- and bilayer graphene in O2, H2 and CF4 plasmas

    International Nuclear Information System (INIS)

    In this work, covalent modification of mono- and bilayer graphene is achieved using tetrafluoromethane (CF4), oxygen and hydrogen RF plasma. Controlled modification of graphene is usually difficult to achieve, in particular with oxygen plasma, which is rather aggressive and usually leads to etching of graphene. Here we use x-ray photoelectron spectroscopy and Raman spectroscopy to show that mild plasma conditions and fine tuning of the number of functional groups can be obtained in all plasmas by varying parameters such as exposure time and sample position inside the chamber. We found that even for the usual harsh oxygen treatment the defect density could be lowered, down to one defect for 3.5 × 104 carbon atoms. Furthermore, we show that CF4 plasma leads to functionalization without etching and that graphene becomes an insulator at saturation coverage. In addition, the reactivity of mono- and bilayer graphene was studied revealing faster modification of monolayer in oxygen and CF4 plasma, in agreement with previous works. In contrast, similar modification rates were observed for both mono- and bilayer during hydrogenation. We attribute this discrepancy to the presence of more energetic species in the hydrogen plasma such as positive ions that could play a role in the functionalization process. (paper)

  3. Fourier transform infrared spectroscopy of CF4 plasmas in the GEC reference cell

    International Nuclear Information System (INIS)

    Fourier transform infrared spectroscopy (FTIR) has been used to characterize inductively coupled CF4 plasmas in a GEC reference cell in situ. In examining these FTIR spectra, several assumptions and approximations of FTIR analysis are addressed. This includes the density dependence of cross-sections, non-linear effects in the addition of overlapping bands and the effect of spatial variations in density and temperature. This analysis demonstrates that temperatures extracted from FTIR spectra may provide a poor estimate of the true neutral plasma temperature. The FTIR spectra are dominated by unreacted CF4, accounting for 40-60% of the gas products. The amount of CF4 consumption is found to have a marked dependence on power, and is nearly independent of pressure in the range of 10-50 mTorr. Small amounts of C2F6 are observed at low power. Also observed are etching products from the quartz window - SiF4, COF2 and CO - which occur in approximately equal ratios and together account for 17-19% of the gas at 300 W and 6-9% of the gas at 100 W. The concentrations of these species are nearly independent of pressure. CFx radicals are below the detection limit of this apparatus (∼1013 cm-3)

  4. Characterization of gadolinium oxide thin films with CF4 plasma treatment for resistive switching memory applications

    International Nuclear Information System (INIS)

    The effect of the CF4 plasma treatment on the gadolinium oxide (GdxOy) thin films for the resistive random access memory (RRAM) applications was investigated. The material properties of the fluorine incorporated GdxOy films were analyzed by the X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and ultraviolet–visible spectroscopy (UV–VIS). Further, the set and reset voltages of the Pt/GdxOy/W RRAM devices with the CF4 plasma treatment were effectively reduced to −1.15 and 2.1 V respectively owing to the low Schottky barrier height. The formation of Gd-F bonds can prevent the oxygen atoms from out-diffusing through Pt grain boundaries into the atmosphere, leading to the superior retention characteristics for over 104 s. The CF4 plasma treated GdxOy RRAMs can sustain a resistance ratio of 102 for more than 800 times stable set/reset cycling, suitable for future low-voltage and high-performance nonvolatile memory operation.

  5. Phase stability in thermally-aged CASS CF8 under heavy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meimei, E-mail: mli@anl.gov [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Miller, Michael K. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Chen, Wei-Ying [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)

    2015-07-15

    Highlights: • Thermally-aged CF8 was irradiated with 1 MeV Kr ions at 400 °C. • Atom probe tomography revealed a strong dose dependence of G-phase precipitates. • Phase separation of α and α′ in ferrite was reduced after irradiation. - Abstract: The stability of the microstructure of a cast austenitic stainless steel (CASS), before and after heavy ion irradiation, was investigated by atom probe tomography (APT). A CF8 ferrite–austenite duplex alloy was thermally aged at 400 °C for 10,000 h. After this treatment, APT revealed nanometer-sized G-phase precipitates and Fe-rich α and Cr-enriched α′ phase separated regions in the ferrite. The thermally-aged CF8 specimen was irradiated with 1 MeV Kr ions to a fluence of 1.88 × 10{sup 19} ions/m{sup 2} at 400 °C. After irradiation, APT analysis revealed a strong spatial/dose dependence of the G-phase precipitates and the α–α′ spinodal decomposition in the ferrite. For the G-phase precipitates, the number density increased and the mean size decreased with increasing dose, and the particle size distribution changed considerably under irradiation. The inverse coarsening process can be described by recoil resolution. The amplitude of the α–α′ spinodal decomposition in the ferrite was apparently reduced after heavy ion irradiation.

  6. Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves

    CERN Document Server

    Hicken, Malcolm; Blondin, Stephane; Challis, Peter; Jha, Saurabh; Kelly, Patrick L; Rest, Armin; Kirshner, Robert P

    2009-01-01

    We combine the CfA3 supernova Type Ia (SN Ia) sample with samples from the literature to calculate improved constraints on the dark energy equation of state parameter, w. The CfA3 sample is added to the Union set of Kowalski et al. (2008) to form the Constitution set and, combined with a BAO prior, produces 1+w=0.013 +0.066/-0.068 (0.11 syst), consistent with the cosmological constant. The CfA3 addition makes the cosmologically-useful sample of nearby SN Ia between 2.6 and 2.9 times larger than before, reducing the statistical uncertainty to the point where systematics play the largest role. We use four light curve fitters to test for systematic differences: SALT, SALT2, MLCS2k2 (R_V=3.1), and MLCS2k2 (R_V=1.7). SALT and SALT2 produce high-redshift Hubble residuals with systematic trends versus color and larger scatter than MLCS2k2. MLCS2k2 overestimates the intrinsic luminosity of SN Ia with 0.7 < Delta < 1.2. MLCS2k2 with R_V=3.1 overestimates host-galaxy extinction while R_V=1.7 does not. Our investi...

  7. Water sorption of CH3- and CF3-Bis-GMA based resins with additives

    Directory of Open Access Journals (Sweden)

    Anuradha Prakki

    2012-08-01

    Full Text Available OBJECTIVES: To evaluate the effect of additives on the water sorption characteristics of Bis-GMA based copolymers and composites containing TEGDMA, CH3Bis-GMA or CF3Bis-GMA. MATERIAL AND METHODS: Fifteen experimental copolymers and corresponding composites were prepared combining Bis-GMA and TEGDMA, CH3Bis-GMA or CF3Bis-GMA, with aldehyde or diketone (24 and 32 mol% totaling 30 groups. For composites, barium aluminosilicate glass and pyrogenic silica was added to comonomer mixtures. Photopolymerization was effected by 0.2 wt% each of camphorquinone and N,N-dimethyl-p-toluidine. Specimen densities in dry and water saturated conditions were obtained by Archimedes' method. Water sorption and desorption were evaluated in a desorption-sorption-desorption cycle. Water uptake (%WU, water desorption (%WD, equilibrium solubility (ES; µg/mm³, swelling (f and volume increase (%V were calculated using appropriate equations. RESULTS: All resins with additives had increased %WU and ES. TEGDMA-containing systems presented higher %WU, %WD, ES, f and %V values, followed by resins based on CH3Bis-GMA and CF3Bis-GMA. CONCLUSIONS: Aldehyde and diketone led to increases in the water sorption characteristics of experimental resins.

  8. Etching characteristic and mechanism of BST thin films using inductively coupled Cl2/Ar plasma with additive CF4 gas

    International Nuclear Information System (INIS)

    BST thin films were etched with inductively coupled CF4/(Cl2+Ar) plasmas. The maximum etch rate of the BST thin films was 53.6 nm/min for a 10% CF4 to the Cl2/Ar gas mixture at RF power of 700 W, DC bias of -150 V, and chamber pressure of 2 Pa. Small addition of CF4 to the Cl2/Ar mixture increased chemical effect. Consequently, the increased chemical effect caused the increase in the etch rate of the BST thin films. To clarify the etching mechanism, the surface reaction of the BST thin films was investigated by X-ray photoelectron spectroscopy

  9. The Effects of an Intensive Behavior and Nutrition Intervention Compared to Standard of Care on Weight Outcomes in CF

    OpenAIRE

    Stark, Lori J.; Opipari-Arrigan, Lisa; Quittner, Alexandra L.; Bean, Judy; Powers, Scott W.

    2010-01-01

    Inadequate intake and suboptimal growth are common problems for patients with CF and a critical target for intervention. The purpose of this study was to compare the growth outcomes of children with CF who participated in a randomized clinical trial to improve energy intake and weight to children with CF receiving standard of care during the same time period. Our primary outcome was change in body mass index z-score (BMI z-score) over 2 years. An exploratory outcome was forced expiratory volu...

  10. Carbon-13 isotopic selectivity in the infrared multiphoton photolysis of CF2Cl2-O2 mixtures

    International Nuclear Information System (INIS)

    The infrared multiphoton chemistry of CF2Cl2-O2 mixtures has been studied at laser frequencies where the product CF2O is highly enriched in carbon-13 yield. Yield enhancements with no loss of isotopic selectivity are attributed to suppression of radical-atom recombination reactions. It is demonstrated that addition of up to 60 Torr of either excess O2 or N2 suppresses a thermal, non-selective channel important at higher fluences. A selectivity factor greater than 30 is observed for 4 Torr CF2Cl2 in the presence of 80 Torr of oxygen

  11. Newborn screening for CF in a regional paediatric centre: the psychosocial effects of false-positive IRT results on parents.

    Science.gov (United States)

    Moran, Janette; Quirk, Kirsten; Duff, Alistair J A; Brownlee, Keith G

    2007-05-01

    Neonatal screening for cystic fibrosis (CF) has been established in Leeds since 1975. The current method is measuring IRT and genotyping. Newborn screening for CF results in a small but significant number of false positives. This study explored the psychosocial reactions to such results in a group of parents (N=21) using semi-structured interviews. Responses were analysed using descriptive statistics and well-validated content analysis. Mothers described a range of emotions during the screening process including anxiety, distress and upset. Waiting for the repeat IRT test results was identified as the most emotionally difficult stage. Discussion focuses on good practice and implications for CF services. PMID:17056302

  12. Separation of NF3 and CF4 using amorphous glassy perfluoropolymer Teflon AF and Hyflon AD60 membranes

    OpenAIRE

    Branken, D.J.; Krieg, H.M.; Lachmann, G.; J. P. Le Roux

    2014-01-01

    In this study, the pure and mixed gas permeabilities of Teflon AF2400, Teflon AF1600 and Hyflon AD60 membranes towards NF3 and CF4 were measured to determine whether membrane gas separation can be applied to purify NF3 of CF4. In accordance with literature results, it was shown that thermal annealing of the solution cast films was necessary to reach optimum performance, wherein all membranes studied had a preferential permeation of NF3 rather than CF4. The Teflon AF and Hyflon AD60 membranes ...

  13. The CF-CIRC study: a French collaborative study to assess the accuracy of Cystic Fibrosis diagnosis in neonatal screening

    Directory of Open Access Journals (Sweden)

    Bellon Gabriel

    2006-10-01

    Full Text Available Abstract Background Cystic fibrosis (CF is caused by mutations in the gene encoding for the CF transmembrane conductance regulator (CFTR protein, which acts as a chloride channel after activation by cyclic AMP (cAMP. Newborn screening programs for CF usually consist of an immunoreactive trypsinogen (IRT assay, followed when IRT is elevated by testing for a panel of CF-causing mutations. Some children, however, may have persistent hypertrypsinogenemia, only one or no identified CFTR gene mutation, and sweat chloride concentrations close to normal values. In vivo demonstration of abnormal CFTR protein function would be an important diagnostic aid in this situation. Measurements of transepithelial nasal potential differences (NPD in adults accurately characterize CFTR-related ion transport. The aim of the present study is to establish reference values for NPD measurements for healthy children and those with CF aged 3 months to 3 years, the age range of most difficult-to-diagnose patients with suspected CF. The ultimate goal of our study is to validate NPD testing as a diagnostic tool for children with borderline results in neonatal screening. Methods/Design We adapted the standard NPD protocol for young children, designed a special catheter for them, used a slower perfusion rate, and shortened the protocol to include only measurement of basal PD, transepithelial sodium (Na+ transport in response to the Na+ channel inhibitor amiloride, and CFTR-mediated chloride (Cl- secretion in response to isoproterenol, a β-agonist in a Cl- free solution. The study will include 20 children with CF and 20 healthy control children. CF children will be included only if they carry 2 CF-causing mutations in the CFTR gene or have sweat chloride concentrations > 60 mEq/L or both. The healthy children will be recruited among the siblings of the CF patients, after verification that they do not carry the familial mutation. Discussion A preliminary study of 3 adult control

  14. EFECTO DEL PARATHION SOBRE EL ÍNDICE DE APOPTOSIS EN HEPATOCITOS DE RATONES CF1 EFFECT OF PARATHION ON THE APOPTOSIS OF CF1 MOUSE HEPATOCYTES

    Directory of Open Access Journals (Sweden)

    Omar Espinoza

    2002-01-01

    Full Text Available En las últimas décadas el uso masivo de agropesticidas órganofosforados, como Parathion y Malathion, ha permitido el control de plagas en la producción hortofrutícola, mejorando la productividad e incrementando la oferta de alimentos de mayor calidad. Sin embargo, pese a su efectividad, estos compuestos químicos son potenciales causantes de daños morfológicos y genéticos, de alto riesgo para la Salud Humana y animal (Draper, 1985; Rodríguez y Bustos-Obregón, 2000. El parathion" (PT, inhibidor de la acetilcolinesterasa, se metaboliza en hígado, pulmón y cerebro. El efecto tóxico se debe a un proceso de desulfuración oxidativa hepática, que transforma el PT en paraoxon (PO, siendo éste su metabolito activo (Chambers y Chambers, 1990; Siller et al., 1997. El objetivo del presente trabajo es evaluar los efectos de una dosis única de PT sobre los índices de apoptosis en hepatocitos de ratón CF1. Se usaron ratones macho CF1 de 8 a 10 semanas, con un peso promedio de 30 g, a los cuales se les aplicó una dosis intraperitoneal única de PT de 20 mg/Kg de peso (Sobarzo y Bustos-Obregón, 2000. Posteriormente fueron sacrificados a 1, 8, 16, 28 y 50 días postratamiento. El análisis histológico del hígado se realizó mediante microscopía óptica sobre cortes teñidos con hematoxilina/eosina en que se analizó la presencia y frecuencia de hepatocitos apoptóticos. Los resultados obtenidos permiten demostrar el efecto del PT sobre el hepatocito con un aumento estadísticamente significativo de apoptosis. Se postula que el PT es carcinogénico, que bloquea o modifica la capacidad de replicación de los hepatocitos, alterando la susceptibilidad del tejido hepático (Fausto, 2000; Metcalfe y Streuli, 1997. Se concluye que el PT tiene un efecto tóxico, aún en dosis consideradas bajas, aumentando significativamente los índices de eventos apoptóticos, alterando el ciclo celular y afectando la histofisiología del tejido hep

  15. A pilot trial on safety and efficacy of erythrocyte-mediated steroid treatment in CF patients

    Directory of Open Access Journals (Sweden)

    Bella S

    2006-05-01

    Full Text Available Abstract Background Chronic neutrophil inflammation of the respiratory tract tissues plays a key role in the pathogenesis and in prognosis of cystic fibrosis (CF. It is evident that an anti-inflammatory therapy represents an important step in the treatment of CF patients. Corticosteroids and ibuprofen have been proven to slow down the impairment of the pulmonary function in CF patients but their use is limited by the frequency of adverse events. A novel strategy for delivering low doses of steroids for long periods through the infusion of autologous erythrocytes loaded with dexamethasone has been recently set up. A recent study suggested the feasibility of therapy with low doses of corticosteroids delivered through engineered erythrocytes in CF patients. This study presents a further analysis of safety and efficacy of this therapy. Methods The treatment group was not randomised and the assignment was based on the patient's consent. Patients entered the study if they had a forced expiratory volume in 1 second (FEV1 Results Nine patients in the experimental group received the treatment once a month for a period of 24 month. Patients did not develop diabetes, cataract, or hypertension, or other typical side effects of steroid treatment during the follow up period. There was a constant improvement of FEV1 in patients undergoing the experimental treatment compared to a gradual decrease of the same parameter in the standard therapy group (P = 0.04. The average of clinic and radiological indexes did not vary. The number of infective relapses that have required antibiotic intravenous therapy was not different in the two groups, although the average of these episodes was slightly higher in the experimental therapy group. Conclusion Intraerythrocyte corticosteroid treatment may stabilize the respiratory function in CF patients but is often considered too invasive by patients. The results obtained by our study may help planning an experimental, controlled

  16. Atmospheric chemistry of HFC-134a. Kinetic and mechanistic study of the CF3CFHO2 + NO2 reaction

    DEFF Research Database (Denmark)

    Møgelberg, T.E.; Nielsen, O.J.; Sehested, J.; Wallington, T.J.; Hurley, M.D.; Schneider, W.F.

    -transform infrared technique was used to investigate the thermal decomposition of the product CF3CFHO2NO2. At 296 K in the presence of 700 Torr of air, decomposition of CF3CFHO2NO2 was rapid (greater than 90% decomposition within 3 min). The results are discussed in the context of atmospheric chemistry of CF3CFH2...

  17. High energy {gamma} emission in the spontaneous fission of {sup 252}Cf; Emission {gamma} de grande energie dans la fission spontanee de {sup 252}Cf

    Energy Technology Data Exchange (ETDEWEB)

    Badimon, C.; Barreau, G.; Doan, T.P.; Pedemay, G. [Centre d`Etudes Nucleaires, Bordeaux-1 Univ., 33 Gradignan (France); Gautherin, C.; Houry, M.; Korten, W.; Le Coz, Y.; Lucas, R.; Thiesen, Ch. [Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee, CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France); Belier, G.; Meot, M.V. [CEA Centre d`Etudes de Bruyeres-le-Chatel, 91 (France); Astier, A.; Ducroux, L.; Meyer, M.; Redon, N. [Inst.de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)

    1997-06-01

    The prompt {gamma} emission in the spontaneous fission of {sup 252}Cf is characterized by an energy spectrum which extends up to 20 MeV. It was established that the spectrum presents in the neighbourhood of symmetric fission an intensity bump in the 3-8 MeV {gamma} energy interval. The origin of this phenomenon is still not well understood, so that it was found interesting to carry out new measurements. The spectrum of the {gamma} rays emitted in spontaneous fission of {sup 252}Cf has been measurement in the EUROGAM II multidetector using photovoltaic cells to detect fragments. The aim of the experiment was to investigate the {gamma} yield enhancement which appears for mass fragment ratio near 132/120. This enhancement was found to be composed of two peaks located at 4 MeV and 5.5 MeV respectively. The results obtained confirm the intensity bound in the 3-8 MeV region but this augmentation reaches the maximum when the heavy fragment is near the mass 132. Beyond mass 140 the phenomenon diminish and the {gamma} spectrum regains the behaviour expected for a statistic emission. The additional structure at 5.5 MeV does not vary with excitation energy while the excitation function of the 4 MeV structure is more structured and presents a maximum when the excitation energy is near 8 MeV. It is likely that all or part of this observed phenomenon is due to a particular excitation mode of this isotope associated for instance with a low energy dipole resonance. A theoretical study of this collective effect is under way 3 refs.

  18. A rapid method for the measurement of sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), and Halon 1211 (CF2ClBr) in hydrologic tracer studies

    Science.gov (United States)

    Busenberg, Eurybiades; Plummer, L. Niel

    2010-01-01

    A rapid headspace method for the simultaneous laboratory determination of intentionally introduced hydrologic tracers, sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), Halon 1211 (CF2ClBr), and other halocarbons in water and gases is described. The high sensitivity of the procedure allows for introduction of minimal tracer mass (a few grams) into hydrologic systems with a large dynamic range of analytical detection (dilutions to 1:108). Analysis times by gas chromatography with electron capture detector are less than 1 min for SF6; about 2 min for SF6 and SF5CF3; and 4 min for SF6, SF5CF3, and Halon 1211. Many samples can be rapidly collected, preserved in stoppered septum bottles, and analyzed at a later time in the laboratory. Examples are provided showing the effectiveness of the gas tracer test studies in varied hydrogeological settings.

  19. A rapid method for the measurement of sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), and Halon 1211 (CF2ClBr) in hydrologic tracer studies

    Science.gov (United States)

    Busenberg, Eurybiades; Plummer, L. Niel

    2010-11-01

    A rapid headspace method for the simultaneous laboratory determination of intentionally introduced hydrologic tracers, sulfur hexafluoride (SF6), trifluoromethyl sulfur pentafluoride (SF5CF3), Halon 1211 (CF2ClBr), and other halocarbons in water and gases is described. The high sensitivity of the procedure allows for introduction of minimal tracer mass (a few grams) into hydrologic systems with a large dynamic range of analytical detection (dilutions to 1:108). Analysis times by gas chromatography with electron capture detector are less than 1 min for SF6; about 2 min for SF6 and SF5CF3; and 4 min for SF6, SF5CF3, and Halon 1211. Many samples can be rapidly collected, preserved in stoppered septum bottles, and analyzed at a later time in the laboratory. Examples are provided showing the effectiveness of the gas tracer test studies in varied hydrogeological settings.

  20. Energy levels of 251Cf populated in the α decay of 100255Fm and EC decay of 99251Es

    International Nuclear Information System (INIS)

    Gamma-ray singles spectra of extremely pure (chemically and isotopically) samples of 255Fm, with strengths of ∼1 mCi, have been measured with a high-resolution 2-cm2x10-mm germanium LEPS detector and with a 25% Ge spectrometer. Gamma rays with intensities as low as 1.0x10-6% per 255Fm α decay have been identified. The electron spectrum of a mass-separated 251Es source was measured with a cooled Si(Li) electron spectrometer. The spectrum provided the conversion coefficients of low-energy transitions in 251Cf and thereby their multipolarities. The present measurements confirm the previous assignments of single-particle states in 251Cf. These include 1/2+[620], 0.0 keV; 7/2+[613], 106.30 keV; 3/2+[622], 177.59 keV; 11/2-[725], 370.47 keV; 9/2-[734], 433.91 keV; 5/2+[622], 543.98 keV; 1/2-[750], 632.0 keV; 9/2+[615], 683 keV; and 9/2+[604], 974.0 keV. A vibrational band was identified in previous studies at 981.4 keV and given an assignment of {7/2+[613]x2-}3/2-. Three new vibrational bands are identified in the present work at 942.5, 1086.5, and 1250.0 keV with tentative assignments {7/2+[613]x1-}5/2-,{7/2+[613]x1-}9/2-, and {7/2+[613]x0+}7/2+, respectively. A level was identified at 1185.5 keV with spin of 5/2 or 7/2 but it was not given any configuration assignment. Another level was identified at 1077.5 keV and given a spin of 9/2. Again, no configuration could be assigned to this level