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Sample records for 14mev neutron cd

  1. FEASIBILITY OF MEASURING IRON IN VIVO USING FAST 14 MEV NEUTRONS.

    WIELOPOLSKI, L.

    2005-05-01

    In this short report, I reassess the feasibility of measuring iron in vivo in the liver and heart of thalassemia patients undergoing chelation therapy. Despite the multiplicity of analytical methods for analyzing iron, only two, magnetic resonance imaging, and magnetic susceptibility, are suitable for in vivo applications, and these are limited to the liver because of the heart's beat. Previously, a nuclear method, gamma-resonance scattering, offered a quantitative measure of iron in these organs; however, it was abandoned because it necessitated a nuclear reactor to produce the radioactive source. I reviewed and reassessed the status of two alternative nuclear methods, based on iron spectroscopy of gamma rays induced by fast neutron inelastic scattering and delayed activation in iron. Both are quantitative methods with high specificity for iron and adequate penetrating power to measure it in organs sited deep within the human body. My experiments demonstrated that both modalities met the stated qualitative objectives to measure iron. However, neutron dosimetry revealed that the intensity of the neutron radiation field was too weak to reliably assess the minimum detection limits, and to allow quantitative extrapolations to measurements in people. A review of the literature, included in this report, showed that these findings agree qualitatively with the published results, although the doses reported were about three orders-of-magnitude higher than those I used. Reviewing the limitations of the present work, steps were outlined for overcoming some of the shortcomings. Due to a dearth of valid quantitative alternatives for determining iron in vivo, I conclude that nuclear methods remain the only viable option. However, from the lessons learned, further systematic work is required before embarking on clinical studies.

  2. Neutron activitation analysis of an air-dust sample using a high-flux 14 Mev neutron generator

    The 14 MeV neutron activation analysis technique is illustrated for multielement analysis of a Milanese air-dust sample. The neutron generator and electronic system, the efficiency and flux calibration, the γ-ray background, the sample preparation and the peak analysis used are described. After careful corrections of all possible interferences and error calculations, the results of 24 elemental concentrations are compared with those of other analytical techniques in the scope of an interlaboratory test. (orig.)

  3. Linking laboratory and in situ activation analysis of rock-forming elements using a 14 Mev neutron source. Doctoral thesis

    Truax, J.

    1995-10-06

    This work examines the ability of a borehole-conveyed delayed neutron activation system to perform elemental analysis of earth formations with the combination of a neutron generator and a large germanium spectrometer. High purity germanium spectrometers are now made large enough that detection efficiency rivals that of borehole-compatible scintillators. Elemental concentrations of silicon, aluminum, magnesium, and sodium are important quantities used in the characterization of rocks. A series of activation spectrometry experiments was performed on chemically pure compounds of these elements in a neutron moderating environment similar to what would pertain in a borehole measurement. Then, the geometry of the experimental setup was entered into a radiation transport modeling code based on a Monte Carlo process. The purpose of this exercise was to compare the measured responses with those predicted by the reaction cross sections in the library of the model, which are often ill-defined for high energy neutron interactions.

  4. Development of a CdTe thermal neutron detector for neutron imaging

    A thin CdTe thermal neutron detector has been developed and its suitability for neutron imaging has been investigated. Simulations of the interaction of neutrons with a 0.5 mm-thick CdTe detector demonstrate the advantages of using 96 keV prompt gamma rays produced by neutron capture in 113Cd as a neutron event. Specifically, they provide a high spatial resolution and approximately the same detection efficiency as 558 keV prompt gamma rays, which are commonly used for detecting thermal neutrons in CdTe detectors. We fabricated a thin CdTe detector. Measurements using a 133Ba gamma-ray source revealed that the detector has a gamma-ray energy resolution of 3 keV at 80 keV, while measurements using a 252Cf neutron source demonstrated that the CdTe detector has good neutron/gamma ray discrimination.

  5. Quadrupole collectivity in neutron-rich Cd isotopes

    The proximity to the closed shells at Z = 50 and N = 82 makes the neutron-rich Cd isotopes a perfect test case for nuclear theories. The energy of the first excited 2+-state in the even 122-128 shows an irregular behaviour as the Cd isotopes exhibit only a slight increase for 122Cd to 126Cd and even a decrease from 126Cd to 128Cd. This anomaly can so far not be reproduced by shell model calculations. Only beyond mean field calculations with a resultant prolate deformation are capable to describe this anomalous behaviour. In order to gain more information about the neutron-rich Cd isotopes a Coulomb excitation experiment was performed with MINIBALL at REX-ISOLDE, CERN. The extracted transition strengths B (E2,0+gs → 2+1) for 122,124,126,128Cd agree with beyond mean field calculations. The spectroscopic quadrupole moments Qs (2+1) are compared with measurements on odd neutron-rich Cd isotopes

  6. Quadrupole collectivity in neutron-rich Cd istotopes

    The neutron-rich cadmium nuclei with a proton number of Z=48 are some of the most interesting isotopes in nuclear structure physics due to the proximity to the proton and neutron shell closures at Z=50 and N=82 respectively. The transition strength B(E2, 0gs+→ 21+) and quadrupole moment Qs(21+) in the even neutron-rich isotopes 122-128Cd was measured in Coulomb excitation experiments with MINIBALL at REX-ISOLDE (CERN). Results of these experiments will pursue the picture of the behaviour of the transition strength towards the neutron shell closure at N=82. A closer insight into the onset of collectivity and the roles played by different orbits can be obtained by the investigation of the odd isotopes. We started this program with the examination of 123Cd where already discrepancies in the level scheme to the literature were evidenced. In this contribution the results of these investigations are presented.

  7. The ferroelectric phase of CdTiO3: A powder neutron diffraction study

    The synthesis of bulk samples of polycrystalline CdTiO3 in both the rhombohedral ilmenite and orthorhombic perovskite forms is described and the structures of these have been refined using powder neutron diffraction data. This involved the preparation of samples enriched in 114Cd. Cooling perovskite-type CdTiO3 to 4 K induces a ferroelectric phase transition, with the neutron data suggesting the low temperature structure is in Pna21. Mode analysis shows the polar mode to be dominant at low temperatures. The ilmenite-structure of CdTiO3 is compared with that of ZnTiO3. The refined scattering length of the 114Cd is estimated to be 5.56 fm. Attempts to dope CdTiO3 with Ca and Sr are described. - Graphical abstract: The structure of three phases of CdTiO3 have been refined using high resolution powder neutron diffraction data. This involved the preparation of samples enriched in 114Cd. Cooling perovskite-type CdTiO3 to 4 K results in a ferroelectric phase in Pna21. Highlights: → Both the ilmenite and perovskite forms of CdTiO3 have been prepared using 114Cd. → Cooling the perovskite form results in a ferroelectric phase. → The structures of these are refined from powder neutron diffraction data. → Attempts to dope CdTiO3 are described.

  8. Investigation of the structure of neutron-deficient Cd isotopes

    Simon, Anna; Humby, P.; Beausang, C. W.; Burke, J. T.; Casperson, R. J.; McCleskey, M.; Saastamoinen, A.; Allmond, J. M.; Chyzh, R.; Dag, M.; Koglin, J.; Ota, S.; Ross, T. J.

    2014-03-01

    The STARLITER setup at Texas A&M University consists of an array of six Compton suppressed HPGe clover γ-ray detectors coupled with a segmented Si ΔE-E charged particle telescope. The combination allows for coincident γ ray and particle spectroscopy and provides a powerful tool for precise determination of the nuclear level structure. A recent experiment conducted using STARLITER aimed at the investigation of structures of neutron-deficient Cd isotopes (A = 104, 105, 106) using an enriched 106Cd target and 35 MeV proton beam supplied by the K-150 Cyclotron at TAMU. Low mass cadmium isotopes are a great environment for analysis of the evolution from vibrational to rotational sequences in A ~100-110 region and provide insight into the structure phenomena around Z = 50 shell closure. Here, the first results of the experiment will be presented. This work was partly supported by the US Department of Energy Grants No. DE-FG52-06NA26206 and No. DE-FG02-05ER41379.

  9. Radiation damage and activation of CdZnTe by intermediate energy neutrons

    The authors exposed a CdZnTe detector to MeV neutrons from a 252Cf source and found no performance degradation for fluences below 1010 neutrons cm-2. Detector resolution did show significant degradation at higher neutron fluences. There is evidence of room temperature annealing of the radiation effects over time. Activation lines were observed and the responsible isotopes were identified by the energy and half-life of the lines. These radiation damage studies allow evaluation of the robustness of CdZnTe detectors in high neutron and radiation environments

  10. Prompt gamma and neutron detection in BNCT utilizing a CdTe detector.

    Winkler, Alexander; Koivunoro, Hanna; Reijonen, Vappu; Auterinen, Iiro; Savolainen, Sauli

    2015-12-01

    In this work, a novel sensor technology based on CdTe detectors was tested for prompt gamma and neutron detection using boronated targets in (epi)thermal neutron beam at FiR1 research reactor in Espoo, Finland. Dedicated neutron filter structures were omitted to enable simultaneous measurement of both gamma and neutron radiation at low reactor power (2.5 kW). Spectra were collected and analyzed in four different setups in order to study the feasibility of the detector to measure 478 keV prompt gamma photons released from the neutron capture reaction of boron-10. The detector proved to have the required sensitivity to detect and separate the signals from both boron neutron and cadmium neutron capture reactions, which makes it a promising candidate for monitoring the spatial and temporal development of in vivo boron distribution in boron neutron capture therapy. PMID:26249745

  11. Neutron scattering studies of Cd1−xMnxTe

    Giebultowicz, T.; Lebech, Bente; Buras, B;

    1984-01-01

    The diluted magnetic (‘‘semimagnetic’’) semiconductor Cd1–xMnxTe reveals intriguing spin glass properties. In this paper, the results of neutron scattering studies of Cd1–xMnxTe are presented. The low‐temperature spin correlations have been studied for several single crystal samples in the...

  12. Neutron-rich In and Cd isotopes close to the doubly-magic $^{132}Sn$

    Scherillo, A.; Genevey, J.; Pinston, J.A.; Covello, A; Faust, H.; Gargano, A.; R. Orlandi; Simpson, G.S.; Tsekhanovich, I.

    2005-01-01

    Microsecond isomers in the In and Cd isotopes, in the mass range A = 123 to 130, were investigated at the ILL reactor, Grenoble, using the LOHENGRIN mass spectrometer, through thermal-neutron induced fission reactions of Pu targets. The level schemes of the odd-mass $^{123-129}$In are reported. A shell-model study of the heaviest In and Cd nuclei was performed using a realistic interaction derived from the CD-Bonn nucleon-nucleon potential

  13. Onset of isomers in 125,126,127,128Cd and weakened neutron-neutron interaction strength

    The presence of isomeric levels with half-lives in the microsecond range has been identified in 125,126,127,128Cd. Neutron-rich Cd isotopes were produced from the fragmentation of a 120 MeV/nucleon 136Xe beam and uniquely identified through their time-of-flight, energy loss, and total kinetic energy. γ rays from these isomeric levels were measured with an array of Ge detectors that were gated for 15 μs by a particle implantation trigger from a stack of Si detectors. The γ rays observed in the decay of 126,128Cd isomers populate low-energy levels previously identified in the β decay of 126,128Ag. The γ rays found in the decay of 125,127Cd isomers are consistent with expected yrast structures observed in lighter, odd-mass Cd isotopes. The appearance of these isomers at the point where N/Z exceeds 1.6 is interpreted as an indication of the onset of a weakened neutron-neutron interaction that has been proposed for 134Sn, whose N/Z also exceeds 1.6

  14. Half-lives of neutron-rich Cd-130128

    Dunlop, R.; Bildstein, V.; Dillmann, I.; Jungclaus, A.; Svensson, C. E.; Andreoiu, C.; Ball, G. C.; Bernier, N.; Bidaman, H.; Boubel, P.; Burbadge, C.; Caballero-Folch, R.; Dunlop, M. R.; Evitts, L. J.; Garcia, F.; Garnsworthy, A. B.; Garrett, P. E.; Hackman, G.; Hallam, S.; Henderson, J.; Ilyushkin, S.; Kisliuk, D.; Krücken, R.; Lassen, J.; Li, R.; MacConnachie, E.; MacLean, A. D.; McGee, E.; Moukaddam, M.; Olaizola, B.; Padilla-Rodal, E.; Park, J.; Paetkau, O.; Petrache, C. M.; Pore, J. L.; Radich, A. J.; Ruotsalainen, P.; Smallcombe, J.; Smith, J. K.; Tabor, S. L.; Teigelhöfer, A.; Turko, J.; Zidar, T.

    2016-06-01

    The β -decay half-lives of Cd-130128 have been measured with the newly commissioned GRIFFIN γ -ray spectrometer at the TRIUMF-ISAC facility. The time structures of the most intense γ rays emitted following the β decay were used to determine the half-lives of 128Cd and 130Cd to be T1 /2=246.2 (21 ) ms and T1 /2=126 (4 ) ms, respectively. The half-lives of the 3 /2+ and 11 /2- states of 129Cd were measured to be T1 /2(3 /2+) =157 (8 ) ms and T1 /2(11 /2-) =147 (3 ) ms. The half-lives of the Cd isotopes around the N =82 shell closure are an important ingredient in astrophysical simulations to derive the magnitude of the second r -process abundance peak in the A ˜130 region. Our new results are compared with recent literature values and theoretical calculations.

  15. Neutron scattering studies of a dilute magnetic semiconductor: Cd1-xMnxTe

    Steigenberger, Ursula; Lebech, Bente; Galazka, Robert R.

    1986-01-01

    The development of the magnetic ordering in the magnetic semiconductor Cd1-xMnxTe was investigated by elastic neutron scattering. A detailed study of the correlation length and the intensity as a function of temperature, direction in reciprocal space and concentration of the magnetic ions has been...

  16. Probing the collectivity in neutron-rich Cd isotopes via γ-ray spectroscopy

    The spin and configurational structure of excited states of 127Cd, 125Cd and 129Cd, having two proton and three, five and one neutron holes, respectively in the doubly magic 132Sn core have been studied. The isomeric states in Cd isotopes were populated in the fragmentation of a 136Xe beam at an energy of 750 MeV/u on a 9Be target of 4 g/cm2. The experiment was performed at GSI Darmstadt. The neutron-rich Cd isotopes were selected using the Bρ - ΔE - Bρ method at the FRagment Separator (FRS). Event by event identification of fragments in terms of their A (mass) and Z (charge) was provided by the standard FRS detectors. The reaction residues were implanted in a plastic stopper surrounded by 15 Ge cluster detectors from the RISING array to detect the γ decays. In 127Cd, an isomeric state with a half-life of 17.5(3) μs has been detected. This yrast (19/2)+ isomer is proposed to have mixed proton-neutron configurations and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone 129Sn. In 125Cd, apart from the previously observed (19/2)+ isomer, two new metastable states at 3896 keV and 2141 keV have been detected. A half-life of 13.6(2) μs was measured for the (19/2)+ isomer, having a decay structure similar to the corresponding isomeric state in 127Cd. The higher lying isomers have a half-life of 3.1(1) μs and 2.5(15) ns, respectively. Time distributions of delayed γ transitions and γγ-coincidence relations were exploited to construct decay schemes for the two nuclei. Comparison of the experimental data with shell-model calculations is also discussed. The new information provides input for the proton-neutron interaction in nuclei around the doubly magic 132Sn core. The γ decays of the isomeric states in 129Cd were not observed experimentally. The reasons for the non-observation of delayed γ rays for 129Cd are either an isomeric half-life of less than 93 ns based on the experimentally obtained isomeric

  17. Neutron resonance spectroscopy on 113Cd: The p-wave levels

    Weak levels in the compound nucleus 114Cd were located by neutron time-of-flight spectroscopy techniques. Neutron capture measurements were performed with both a natural cadmium target and a highly enriched 113Cd target. A total of 22 new resonances were located in the neutron energy interval 20-500 eV and were assumed to be p-wave. Resonance parameters, E0 and gΓn, are given for the newly identified levels. The p-wave strength function was determined to be 104S1=2.8±0.8 and the average level spacing left-angle D1 right-angle=14 eV. Comparison of the reduced widths with a Porter-Thomas distribution is consistent with having missed 15% of the p-wave levels

  18. Neutron generation by laser irradiation of CD4 clusters

    It was shown in 1999 that D2 cluster explosion under ultrashort intense laser irradiation can lead to ion energies sufficient to drive nuclear fusion reactions [Ditmire et al. Nature 398, 491]. We show how the use of molecular clusters allows to further enhance the ionic acceleration, allowing one to reach optimal fusion cross sections. A new low density high energy regime is described, in which fusion occurs via a spallation-like process. The process increases with laser intensity up to the relativistic threshold, at which the neutron production is overwhelmed by gamma production resulting from electron acceleration

  19. Structural changes at large angular momentum in neutron-rich Cd,123121

    Rejmund, M.; Navin, A.; Bhattacharyya, S.; Caamaño, M.; Clément, E.; Delaune, O.; Farget, F.; de France, G.; Jacquot, B.; Lemasson, A.

    2016-02-01

    Prompt γ rays of isotopically identified neutron-rich isotopes of Cd, produced in transfer- and fusion-fission induced by the 238U beam at 6.2 MeV/u on a 9Be target, were measured using the EXOGAM γ -ray detector array and the magnetic spectrometer VAMOS++. New results for the level scheme of Cd,123121, extending to relatively large angular momentum are reported. The energy levels above 2-MeV excitation energy, are found to differ from those observed in lighter isotopes of Cd indicating a change in structure in these more neutron-rich nuclei. These states are not explained by large-scale shell model calculations, that explain well the structure of the underlying Sn isotopes and the neighboring even-A Cd isotopes. The present data, especially for the odd-A nuclei, point to a deficiency in the matrix elements related to the p-n residual interaction and provide a new domain for testing widely used shell model interactions employed for understanding the evolution of structure in neutron-rich nuclei.

  20. Neutron resonance spectroscopy on 113Cd to En=15 keV

    The results of a study of the compound nucleus 114Cd by neutron time-of-flight spectroscopy methods are presented. Targets of both natural cadmium and cadmium enriched in the 113 isotope were used. The neutron total capture and neutron transmission were both measured. A total of 275 new resonances were located. In addition, 102 other resonances which were previously known but not assigned to a particular cadmium isotope were definitively assigned to 113Cd. Resonance parameters E0 and gΓn were obtained for both newly identified and previously known resonances. Of the 437 resonances now known in 113Cd, we identify 104 of them as l=1 based on their small widths. Strength functions and level spacings are obtained for both l=0 and l=1 resonances. Comparisons of the data with Porter-Thomas reduced width distributions, Wigner nearest neighbor spacing distributions, and the Dyson-Metha Δ3 statistic are given. The linear correlation coefficient between adjacent spacings is also discussed. The spectroscopic information obtained is of importance for planning and interpretation of parity violation measurements on the p-wave resonances of 113Cd

  1. Gamow-Teller beta decay of the very neutron deficient $N=50$ nucleus $^{98}$Cd

    Grant, I S; Batsch, T; Plochocki, A; Zylicz, J; Barden, R; Klepper, O; Schardt, D; Szerypo, J; Gabelmann, H; Hill, P; Ravn, H L

    1992-01-01

    For the first time, detailed decay-spectroscopic investigations were performed for the very neutron-deficientN=50 nuclide98Cd. The98Cd activity was produced in spallation reactions between 600 MeV protons and a natural tin target, yielding a98Cd beam intensity of 10 to 60 atoms/s at the collector of the ISOLDE massseparator. By means ofγ-ray and conversion-electron spectroscopy, 19 transitions were found to follow the β+/EC decay98Cd→98Ag. The transitions at 61 and 107 keV were shown to beM1(+E2) andE2, respectively, and the98Cd half-life was measured as 9.2±0.3 s. TheQ EC value of98Cd is determined semiempirically and is compared to model predictions together with the measuredQ EC values of the neighbouring cadmium isotopes100,102Cd and theN=50 isotones92Mo,94Ru, and96Pd, taken from the literature. The newly established decay scheme of98Cd includes 9 excited states of98Ag. Four states at 1691, 1861, 2164, and 2544 keV are directly fed by 0+ → 1+ Gamow-Teller beta transitions with a summed strength of ...

  2. Measurements of absolute γ-ray intensities in the decays of very neutron rich isotopes of Cd and In

    The half lives and the γ-ray branching ratios of neutron rich Cd and In isotopes have been investigated by simultaneous measurements of β- and γ-ray spectra. The results presented contain information on 21 different β-decaying isotopes or isomers of Cd and In in the mass region A=123-129. Four previously unknown or little known isotopes of Cd are reliably characterized for the first time. (orig.)

  3. Spins of resonances in reactions of neutrons with (238)U and (113)Cd. Doctoral thesis; Spins van resonanties in reacties van neutronen met (238)u en (113)cd

    Gunsing, F.

    1994-12-31

    In this thesis experiments are described that have lead to the assignments of spins to a large number of resonances in reactions of epithermal neutrons with the nuclei (238)U and (113)Cd. When a neutron is captured by an atomic nucleus, a compound nucleus is formed which is in a highly excited state with an energy of the order of the neutron binding energy. If the kinetic neutron energy is varied around a state of the compound nucleus, one observes a peak in the cross section. This is called a resonance in the reaction. Dependent on the amount or orbital momentum l that the neutron adds to the system, the resonances are indicated with spectroscopic notations as s- and p-waves for l = 0 and 1 respectively. The purpose of this thesis is to determine the spins of such resonances.

  4. Spherical proton-neutron structure of isomeric states in 128Cd

    The γ-ray decay of isomeric states in the even-even nucleus 128Cd has been observed. The nucleus of interest was produced both by the fragmentation of 136Xe and the fission of 238U primary beams. The level scheme was unambiguously constructed based on γγ coincidence relations in conjunction with detailed lifetime analysis employed for the first time on this nucleus. Large-scale shell-model calculations, without consideration of excitations across the N=82 shell closure, were performed and provide a consistent description of the experimental level scheme. The structure of the isomeric states and their decays exhibit coexistence of proton, neutron, and strongly mixed configurations due to πν interaction in overlapping orbitals for both proton and neutron holes

  5. Collective excitations in liquid CD4: Neutron scattering and molecular-dynamics simulations

    Guarini, E.; Bafile, U.; Barocchi, F.; Demmel, F.; Formisano, F.; Sampoli, M.; Venturi, G.

    2005-12-01

    We have investigated the dynamic structure factor S(Q,ω) of liquid CD4 at T = 97.7 K in the wave vector range 2 <= Q/nm-1 <= 15 by means of neutron scattering and molecular-dynamics simulation, in order to study the centre-of-mass collective dynamics. The agreement between the experimental spectra and those simulated using a recent ab initio based intermolecular potential is good, particularly at low Q. Underdamped collective excitations, detected in the whole experimental Q-range, characterize the dynamics of liquid CD4 as markedly different from that of other molecular liquids. Also, the energy and damping of collective excitations in methane are shown to differ considerably, even at the lowest measured Q-values, from those of linearized hydrodynamic modes. An empirical relation, able to reconcile the different wave vector ranges of mode propagation observed in disparate liquids, is investigated.

  6. Coulomb excitation of neutron-rich odd-$A$ Cd isotopes

    Reiter, P; Kruecken, R; Gernhaeuser, R A; Kroell, T; Leske, J; Marginean, N M

    We propose to study excited states in the odd-${A}$ isotopes $^{123,125,127}$Cd by ${\\gamma}$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to determine the B(E2) values connecting excited states with the ground state as well as the long-lived (11/2$^{-}$) isomer. The proposed study profits from the unique capability of ISOLDE to produce beams containing Cd in the ground state or in the isomeric state. Our recent results on the neutron-rich even-A Cd nuclei appear to show that these nuclei may possess some collectivity beyond that calculated by modern shell-model predictions. Beyond-mean-field calculations also predict these nuclei to be weakly deformed. These facets are surprising considering their proximity to the doubly magic $^{132}$Sn. Coulomb-excitation studies of odd-${A}$ Cd isotopes may give a unique insight into the deformation-driving roles played by different orbits in this region. Such studies of the onset of collectivity become especially important in light of recent...

  7. Local distortions revealed by neutron holography in SnCd0.0026 alloy

    Szakál, Alex; Markó, Márton; Cser, László

    2016-05-01

    Local distortions of the ideal periodic structure in crystals around impurity atoms play an important role in various physical properties of materials. The aim of this study was to investigate the static distortions around cadmium impurity atoms in a SnCd0.0026 single crystal using atomic resolution neutron holography technique. The cadmium nucleus was used as an inside detector to measure the holographic interference pattern from which the three-dimensional (3D) atomic arrangement of tin nuclei around the cadmium impurities was reconstructed. Detailed analysis of the reconstructed image revealed the 3D static displacements of Sn atoms around the impurity. It was found that the crystal structure contracts around the cadmium impurity atom and the displacements tend to transform the crystal to the α phase. The local contraction of the lattice was used to explain the slower phase transformation to α -Sn phase when Cd impurity atoms are present. The study shows the ability of neutron holography to measure 3D displacements around impurities which can be used, e.g., to understand the mechanisms that block the phase transformations in the presence of impurities.

  8. On the origin of the anomalous behaviour of 2+ excitation energies in the neutron-rich Cd isotopes

    Recent experimental results obtained using β decay and isomer spectroscopy indicate an unusual behaviour of the energies of the first excited 2+ states in neutron-rich Cd isotopes approaching the N=82 shell closure. To explain the unexpected trend, changes of the nuclear structure far-off stability have been suggested, namely a quenching of the N=82 shell gap already in 130Cd, only two proton holes away from doubly magic 132Sn. We study the behaviour of the 2+ energies in the Cd isotopes from N=50 to N=82, i.e. across the entire span of a major neutron shell using modern beyond mean field techniques and the Gogny force. We demonstrate that the observed low 2+ excitation energy in 128Cd close to the N=82 shell closure is a consequence of the doubly magic character of this nucleus for oblate deformation favoring thereby prolate configurations rather than spherical ones

  9. $\\beta$-delayed neutron spectroscopy of $^{130-132}$ Cd isotopes with the ISOLDE decay station and the VANDLE array

    We propose to use the new ISOLDE decay station and the neutron detector VANDLE to measure the $\\beta$-delayed neutron emission of N=82-84 $^{130-132}$Cd isotopes. The large delayed neutron emission probability observed in a previous ISOLDE measurement [M. Hannawald et al., Phys. Rev. C62, 054301 (2000)] is indicative of the Gamow-Teller transitions due to the decay of deep core neutrons. Core Gamow-Teller decay has been experimentally proven in the $^{78}$Ni region for the N>50 nuclei using the VANDLE array. The spectrocopic measurement of delayed neutron emission along the cadmium isotopic chain will allow us to track the evolution of the single particle states and the shell gap.

  10. The coupling of the Star-Cd software to a whole-core neutron transport code Decart for PWR applications

    As part of a U.S.- Korea collaborative U.S. Department of Energy INERI project, a comprehensive high-fidelity reactor-core modeling capability is being developed for detailed analysis of existing and advanced PWR reactor designs. An essential element of the project has been the development of an interface between the computational fluid dynamics (CFD) module, STAR-CD, and the neutronics module, DeCART. Since the computational mesh for CFD and neutronics calculations are generally different, the capability to average and decompose data on these different meshes has been an important part of code coupling activities. An averaging process has been developed to extract neutronics zone temperatures in the fuel and coolant and to generate appropriate multi group cross sections and densities. Similar procedures have also been established to map the power distribution from the neutronics zones to the mesh structure used in the CFD module. Since MPI is used as the parallel model in STAR-CD and conflicts arise during initiation of a second level of MPI, the interface developed here is based on using TCP/IP protocol sockets to establish communication between the CFD and neutronics modules. Preliminary coupled calculations have been performed for PWR fuel assembly size problems and converged solutions have been achieved for a series of steady-state problems ranging from a single pin to a 1/8 model of a 17 x 17 PWR fuel assembly. (authors)

  11. Study of Neutron-Rich $^{124,126,128}$Cd Isotopes; Excursion from Symmetries to Shell-Model Picture

    Nieminen, A M; Reponen, M

    2002-01-01

    A short outline is given on a number of topics that are present in the long series of even-even Cd nuclei and therefore, may turn out to constitute an ideal test bench in order to verify a number of theoretical ideas on how collective motion, near closed shells, builds up taking into account both the valence and core nucleons when studying the nucleon correlations. Moreover, these experiments can reveal new challenges when moving towards very neutron-rich systems.

  12. Neutron Knockout on Beams of $^{108,106}$Sn and $^{106}$Cd

    Cerizza, Giordano

    2015-01-01

    Characterizing the nature of single-particle states outside of double shell closures is essential to a fundamental understanding of nuclear structure. This is especially true for those doubly magic nuclei that lie far from stability and where the shell closures influence nucleo-synthetic pathways. The region around $^{100}$Sn is one of the most important due to the proximity of the N=Z=50 magic numbers, the proton-drip line, and the end of the rp-process. However, owing to the low production rates, there is a lack of spectroscopic information and no firm spin-parity assignment for ground states of odd-A isotopes close to $^{100}$Sn. Neutron knockout reaction experiments on beams of $^{108,106}$Sn and $^{106}$Cd have been performed at the NSCL. By measuring gamma rays and momentum distributions from reaction residues, the spin of ground state and first excited state for $^{107,105}$Sn have been established. The results also show a degree of mixing in the ground states of the isotopes $^{108,106}$Sn between the...

  13. Neutron emission asymmetries from linearly polarized γ rays on ^natCd, ^natSn, and ^181Ta

    Clarke Smith, W.; Feldman, Gerald

    2011-10-01

    Azimuthal asymmetries in neutron yields produced by bombarding targets with linearly polarized photons via (γ,n), (γ,2n), and (γ,f) reactions are being investigated as a possible means of identifying various nuclear isotopes. The High Intensity γ-ray Source (HIγS) at Duke University provides nearly monochromatic, circularly or linearly polarized γ rays with high intensity by Compton backscattering free-electron-laser photons from stored electrons. Linearly polarized γ rays produced by HIγS were incident on ^natCd, ^natSn, and ^181Ta targets at six energies Eγ between 11.0 and 15.5 MeV and emitted neutrons were detected both parallel and perpendicular to the plane of polarization by an array of 18 liquid-scintillator detectors at angles in the range θ=55^o--142^o. Detected neutrons were distinguished from Compton scattered photons by pulse-shape-discrimination and timing cuts, and their energies (En) were determined using time-of-flight information over a 0.5 m flight path. The characteristic plots of Rn, the ratio of neutron counts parallel to neutron counts perpendicular to the plane of the incident γ-ray polarization, against En were constructed for each value of Eγ and θ and then compared to those for other targets studied at HIγS, including fissile nuclei ^235U and ^238U.

  14. Nuclear spectroscopic studies on the nucleus 107Cd using an apparature for the measurement of neutron-gamma angular correlations

    In the present thesis an apperature for the measurement of n-γ angular correlations was developed. With that the nucleus 107Cd was studied using the reaction 107Ag(p,nγ) 107Cd. The analysis of the measured angular distributions yields by comparison with the calculated angular distribution a number of hitherto not yet or only uncertainly determined spins. Especially for levels, for which from neutron transfer experiments the orbital angular momentum of the transferred neutron was determined to lsub(n) = 2, a decision for spin 3/2+ or 5/2+ could be made. For a number of levels in addition to the spins the multipole mixing parameter of the γ-radiation could be determined. Using the obtain multipole mixing parameters and lifetimes from the measurement of Gompf using the Doppler shift attenuation method statements about the excitation character of some levels could be made. For this in the particle-core coupling model a wave function with two components was assumed, a pure particle wave function and a coupled core-particle excitation. By the knowledge of multipole mixing parameter and lifetime the amplitudes of the wave function are determined. (orig./HSI)

  15. Simultaneous cloud point extraction of low levels of Cd, Cr and Hg in seaweed species prior to neutron activation analysis

    A one-step preconcentration cloud point extraction (CPE) method has been developed for the simultaneous determination of Cd, Cr, and Hg using a mixture of 1-(2-pyridylazo)-2-naphthol (PAN) and 1-(2-thiazolylazo)-2-naphthol (TAN) chelating agents and polyoxyethylene nonylphenylether-20 (PONPE-20) surfactant. The pH concentration of PAN and TAN, concentration of PONPE-20, ionic strength and temperature affecting the separation were optimized. The recoveries of each of the elements under the optimum conditions of pH 8.6, (PAN/TAN) = 1 X 10-4 M, (PONPE-20) = 0.1 % (m/v), ionic strength = 0.05 M KNO3, and temperature of 41 0C were > 98%. The concentrations of the elements were determined by neutron activation analysis using the Dalhousie University Slowpoke-2 reactor (DUSR) facility. The detection limits of Cd, Cr and Hg were 6.0, 3.6 and 1.2 ng g-1 respectively, and precision and accuracy of measurements were evaluated. The method was successfully applied to the simultaneous determination of Cd, Cr and Hg in fifteen Ghanaian seaweed species. (au)

  16. International comparison of Cd content in a quality control material of Navajuelas (Tagelus dombeii) determined by anodic stripping voltammetry, atomic absorption spectrometry and neutron activation analysis

    Queirolo, F. (Universidad Catolica del Norte, Antofagasta (Chile). Dept. of Chemistry Forschungszentrum Juelich GmbH (Germany, F.R.). Inst. fuer Angewandte Physikalische Chemie Universidad de Extremadura, Badajoz (Spain). Dept. of Analytical Chemistry and Electrochemistry); Ostapczuk, P. (Forschungszentrum Juelich GmbH (Germany, F.R.). Inst. fuer Angewandte Physikalische Chemie); Valenta, P.; Stegen, S. (Forschungszentrum Juelich GmbH (Germany, F.R.). Inst. fuer Angewandte Physikalische Chemie Universidad de Extremadura, Badajoz (Spain). Dept. of Analytical Chemistry and Electrochemistry); Marin, C.; Vinagre, F.; Sanchez, A. (Universidad de Extremadura, Badajoz (Spain). Dept. of Analytical Chemistry and Electrochemistry)

    1991-05-01

    The determination of Cd was performed by neutron activation analysis (NAA), atomic absorption spectrometry (AAS) with flame or in the electrothermal mode and anodic stripping voltammetry in the differential pulse mode (DPASV) and the square wave mode (SWASV). (orig./EF).

  17. Measurement of the neutron spectrum in a room with an accelerator Varian 2300C/D Linac using the Bonner multisphere spectrometer

    The generated neutron field varies considerably and depends on the beam energy, on the shielding of the accelerator, on the filters for beam homogeneity, and also on the mobile collimators and geometry of irradiation. The estimation of the component relative to the photoneutrons has practical interest for evaluation of the radiological risks for the workers and for the patient as well. Due to the high frequency magnetic field, and to the photon abundance resulting of the escape and scattering at treatment room, those measurements present some difficulties. Measurements of the neutron fields can be made with a Bonner spectrometer. Those system was calibrated with referred neutron standard sources and used for make measurements on a spot of the room where a Variant 2300C/D Linac is installed. The unfolding process used the BUNKI computer code for determination of the neutron spectra at the measurement spot

  18. Strength functions for transfer of a neutron-proton pair on 82Se, 96Mo, 116Cd and 128Te nuclei

    This study presents the calculation of strength functions for neutron-proton pair transfer on 82Se, 96Mo, 116Cd and 128Te even-even nuclei. We study 1+ states, which are a part of the Gamow-Teller (GT) giant resonances in neighboring odd-odd nuclei, excited via the neutron-proton pair transfer on even-even parent nuclei. The main result of this work is to find these states using strength functions. Calculations have been made only in the particle-particle channel of charge-exchange spin-spin forces via the random phase approximation (RPA).

  19. Neutron Scattering Studies of the Anti-ferromagnetic Phase of Cd1-xMnxTe

    Giebultowicz, T.; Minor, W.; Buras, B.; Lebech, Bente; Galazka, R. R.

    1982-01-01

    Studies of the magnetic properties of crystals of the mixed semiconductors Cd1-xMnxTe indicate that: (i) for x ≤ 0.17 the crystals are paramagnetic at all temperatures, (ii) for 0.17

  20. Simultaneous preconcentration of Cd, Cr and Hg in seaweeds by cloud point extraction using PAN/TAN and neutron activation

    A simple one-step green chemistry method for the simultaneous preconcentration of Cd, Cr, and Hg in seaweed samples has been developed. The method is based on the separation phenomenon of non-ionic surfactant polyoxyethylene nonyl ether (PONPE-20) in aqueous solutions after the formation of a complex with a mixture of two chelating agents, namely, 1-(2-pyridylazo)-2-naphthol (PAN) and 1-(2-thiazolylazo)-2-naphthol (TAN). The chemical variables affecting the separation phase were optimized. The recoveries of these elements under the optimum conditions, namely pH=8.5, (PAN/TAN)=1x10-4 M, (PONPE-20)=0.1% (wt) , ionic strength=0.05 M KNO3, T=40 deg C, and preconcentration of 20-30 mL of sample solutions, were found to be >98%. The samples were irradiated in the inner sites of the Dalhousie University SLOWPOKE-2 reactor (DUSR) facility at a thermal neutron flux of 2.5 x 1011 cm-2 s-1

  1. Microscopic quasiparticle-phonon description of beta decays of {sup 113}Cd and {sup 115}In using proton-neutron phonons

    Mustonen, M.T. [Department of Physics, University of Jyvaeskylae, PO Box 35, FIN-40351 Jyvaeskylae (Finland)], E-mail: mika.t.mustonen@jyu.fi; Suhonen, J. [Department of Physics, University of Jyvaeskylae, PO Box 35, FIN-40351 Jyvaeskylae (Finland)], E-mail: jouni.suhonen@phys.jyu.fi

    2007-11-29

    The fourth-forbidden non-unique ground-state-to-ground-state beta decays of {sup 113}Cd and {sup 115}In are calculated using a realistic microscopic two-body interaction and a realistic single-particle model space. To describe the involved initial and final nuclear states we introduce a proton-neutron variant of the microscopic quasiparticle-phonon model (MQPM), the proton-neutron MQPM (pnMQPM). The states of the pnMQPM are created by coupling quasiparticles with phonons of the proton-neutron quasiparticle random-phase approximation (pnQRPA). The computed half-lives and logft values are found to be in excellent agreement with experimental data. Computed beta spectra of the decays are also given.

  2. The structural properties of CdO-Bi 2 O 3 borophosphate glass system containing Fe 2 O 3 and its role in attenuating neutrons and gamma rays

    Saudi, H. A.; Mostafa, A. G.; Sheta, N.; El Kameesy, S. U.; Sallam, H. A.

    2011-11-01

    A glass system with chemical formula xBi 2O 3-(30- x)CdO-10B 2O 3-20Fe 2O 3-40P 2O 5 (0≤ x≤30) wt% is prepared to be used as radiation shield. The mass attenuation coefficient and half value layer of the glass system to gamma rays have been measured experimentally and compared with those determined from theoretical calculations using the mixture rule of WinXCom program. A database of effective mass removal cross-sections for fast neutrons is also introduced in this work. The obtained results of this study are correlated to the structural properties of these glasses obtained from their IR spectra and the influence of gamma and neutrons irradiation on these structural properties.

  3. Use of new composite materials for the determination of Cu, Cd, Mo, As, and Sb in biological samples by radiochemical neutron activation analysis

    New composite materials were developed and tested for determination of Cu, Cd, Mo, As, and Sb in biological materials by radiochemical neutron activation analysis (RNAA). The materials were prepared by incorporation of solid zinc diethyldithiocarbamate or liquid bis(2,4,4- trimethylpentyl)dithiophosphinic acid (CYANEX 301) into a polyacrylonitrile (PAN) binding matrix. The accuracy of the RNAA methods developed was proved by analysis of NIST SRM-1515 Apple Leaves, NIST SRM-1577b Bovine Liver, and NIST SRM-1549 Non Fat Milk Powder. (author)

  4. E1 and E2 cross sections of the 12C(α,γ)16O reaction at Ecm∼1.4 Mev using pulsed α beams

    We have installed a new system to measure the γ-ray angular distribution of the 12C(α,γ)16O reaction at the 3.2 MV Pelletron accelerator laboratory at Tokyo Institute of Technology to accurately determine the E1 and E2 cross sections. In this experiment, we used high efficiency anti-Compton NaI(T1) spectrometers to detect a γ-ray from the reaction with a large S/N ratio, intense pulsed α beams to discriminate true events from neutron induced background with a time-of-flight (TOF) method, and the monitoring system of target thickness. We succeeded in removing a background due to neutrons and could clearly detect the γ-ray from the 12C(α,γ)l6O reaction with high statistics

  5. $\\beta$-decay study of very neutron-rich Cd isotopes with a chemically selective laser ion source

    2002-01-01

    Following our test measurements of N=82-84 Cd isotopes with a specifically developed laser ion source (CERN/ISC 97-16, ISC/I 22), we now propose detailed spectroscopic studies of the decay of $^{130}$Cd to $\\,^{132}\\!$Cd, and at least the determination of some gross properties of the new N=85-86 nuclides $^{133}\\!$Cd and $\\,^{134}\\!$Cd. The main nuclear-structure objective of this experiment is the identification of the energies of the single-hole (SH) proton states in $^{131}$In. Nearly all of the other single-nucleon shell-model basis energies around doubly magic $^{132}$Sn are known by now, except those $\\pi$SH in Z=49 $\\,^{131}$In. Theoretical agreement on these values has not been achieved so far. Of particular interest is the depth of the $\\pi$f$_{5/3}$ hole and the p$_{3/2}$ - p$_{1/2}$ spin-orbit splitting. A second important goal is the determination of the position of the lowest-energy 1$^+\\,$ level in $^{130}$In predominantly populated in the Gamow-Teller (GT) decay of N=82 $^{130}\\!$Cd. Apart from...

  6. Measurement of cross sections producing short-lived nuclei by 14MeV neutron. Cd, Sn, Te, Nd, Gd, Re

    Sakane, H.; Yamamoto, H.; Kawade, K. [Nagoya Univ. (Japan); Iida, T.; Takahashi, A.

    1998-03-01

    Nine neutron activation cross sections producing the nuclei with half-lives between 25sec and 22min were measured at energy range between 13.4 and 14.9 MeV by activation method. The (n,p) and (n,{alpha}) reaction cross sections were measured for the isotopes of {sup 110}Cd, {sup 112}Sn, {sup 122}Te, {sup 130}Te and {sup 185}Re and those of {sup 130}Te, {sup 148}Nd and {sup 158}Gd, respectively. The present results were compared with our systematics proposed on the basis of 58 cross section data of (n,p) and 33 data of (n,{alpha}) reaction. Good agreements have been seen between them. (author)

  7. Neutron scattering studies on phase transitions in (CD3ND3)2CuCl4 and MnCl2.4H2O

    In this thesis the results of neutron scattering experiments and measurements of the susceptibility on some compounds which display magnetic and/or structural phase transitions, are described. Following an introductory chapter, chapter 2 shows that neutron scattering can be used as a tool for unravelling problems in crystallographic and magnetic structure. The qualitative different scattering patterns for scatters are described. In chapters 3 and 4 an investigation on the layered ferromagnets (CH3NH3)2CuCl4 and (CD3ND3)2CuCl4 is described. In these materials the copper ions, which carry the magnetic moment, are more closely spaced in the ab-planes, and consequently the magnetic interactions in these planes are stronger than those in the direction perpendicular to these planes by about a factor of 105. Chapter 5 presents a discussion and a calculation of demagnetizing and dipole fields. The second part of this thesis is concerned with the transition from the antiferromagnetic to the paramagnetic phase in MnCl2.4H2O in the presence of a magnetic field applied perpendicular to the preferred direction of the magnetic moments. The theory is reviewed in chapter 6 and in chapter 7 the correction procedure for inhomogeneous internal fields is applied to the measurements on MnCl2.4H2O. (Auth./C.F.)

  8. Concentration-dependent binding of CO2 and CD4 in UiO-66(Zr): A combination of neutron powder diffraction and first-principle DFT calculations

    Over the last twenty years, tremendous progress has been achieved in the field of Metal Organic Frameworks. Among these materials, the zirconium terephthalate UiO-66(Zr) [1] has attracted a growing attention because of its interesting thermal, chemical and water stability and has shown to be a promising material for the separation of CO2/CH4 gas mixtures. In order to get a better understanding of its sorption behavior towards these gases, a Neutron Powder Diffraction (NPD) investigation of UiO-66 loaded with sequential doses of CO2 and CD4 has been carried out on the High Resolution Powder Diffractometer instrument “Echidna” at the OPAL reactor (ANSTO, Sydney). In total, three adsorption sites for CO2 and three adsorption sites for CD4 within the UiO-66(Zr) have been located by NPD then characterized by a combination of first-principles Density Functional Theory (DFT) calculations, binding energies and Quantum Theory of Atoms In Molecules (QTAIM) theory. An example of the first CO2 adsorption site is given in figure 1.

  9. Precision Mass Measurements of ^{129-131}Cd and Their Impact on Stellar Nucleosynthesis via the Rapid Neutron Capture Process.

    Atanasov, D; Ascher, P; Blaum, K; Cakirli, R B; Cocolios, T E; George, S; Goriely, S; Herfurth, F; Janka, H-T; Just, O; Kowalska, M; Kreim, S; Kisler, D; Litvinov, Yu A; Lunney, D; Manea, V; Neidherr, D; Rosenbusch, M; Schweikhard, L; Welker, A; Wienholtz, F; Wolf, R N; Zuber, K

    2015-12-01

    Masses adjacent to the classical waiting-point nuclide ^{130}Cd have been measured by using the Penning-trap spectrometer ISOLTRAP at ISOLDE/CERN. We find a significant deviation of over 400 keV from earlier values evaluated by using nuclear beta-decay data. The new measurements show the reduction of the N=82 shell gap below the doubly magic ^{132}Sn. The nucleosynthesis associated with the ejected wind from type-II supernovae as well as from compact object binary mergers is studied, by using state-of-the-art hydrodynamic simulations. We find a consistent and direct impact of the newly measured masses on the calculated abundances in the A=128-132 region and a reduction of the uncertainties from the precision mass input data. PMID:26684113

  10. Precision Mass Measurements of 129-131Cd and Their Impact on Stellar Nucleosynthesis via the Rapid Neutron Capture Process

    Atanasov, D; Blaum, K; Cakirli, R B; Cocolios, T E; George, S; Herfurth, F; Kisler, D; Kowalska, M; Kreim, S; Litvinov, Yu A; Lunney, D; Manea, V; Neidherr, D; Rosenbusch, M; Schweikhard, L; Welker, A; Wienholtz, F; Wolf, R N; Zuber, K

    2015-01-01

    Masses adjacent to the classical waiting-point nuclide 130Cd have been measured by using the Penning- trap spectrometer ISOLTRAP at ISOLDE/CERN. We find a significant deviation of over 400 keV from earlier values evaluated by using nuclear beta-decay data. The new measurements show the reduction of the N = 82 shell gap below the doubly magic 132Sn. The nucleosynthesis associated with the ejected wind from type-II supernovae as well as from compact object binary mergers is studied, by using state-of-the-art hydrodynamic simulations. We find a consistent and direct impact of the newly measured masses on the calculated abundances in the A = 128 - 132 region and a reduction of the uncertainties from the precision mass input data.

  11. Effect of external shielding for neutrons during radiotherapy for prostate cancer, considering the 2300 CD linear accelerator and voxel phantom

    Thalhofer, J. L.; Roque, H. S.; Rebello, W. F.; Correa, S. A.; Silva, A. X.; Souza, E. M.; Batita, D. V. S.; Sandrini, E. S.

    2014-02-01

    Photoneutron production occurs when high energy photons, greater than 6.7 MeV, interact with linear accelerator head structures. In Brazil, the National Cancer Institute, one of the centers of reference in cancer treatment, uses radiation at 4 angles (0°, 90°, 180° and 270°) as treatment protocol for prostate cancer. With the objective of minimizing the dose deposited in the patient due to photoneutrons, this study simulated radiotherapy treatment using MCNPX, considering the most realistic environment; simulating the radiotherapy room, the Linac 2300 head, the MAX phantom and the treatment protocol with the accelerator operating at 18 MV. In an attempt to reduce the dose deposited by photoneutrons, an external shielding was added to the Linac 2300. Results show that the equivalent dose due to photoneutrons deposited in the patient diminished. The biggest reduction was seen in bone structures, such as the tibia and fibula, and mandible, at approximately 75%. Besides that, organs such as the brain, pancreas, small intestine, lungs and thyroid revealed a reduction of approximately 60%. It can be concluded that the shielding developed by our research group is efficient in neutron shielding, reducing the dose for the patient, and thus, the risk of secondary cancer, and increasing patient survival rates.

  12. First direct mass measurements of stored neutron-rich 129,130,131Cd isotopes with FRS-ESR

    Knöbel, R.; Diwisch, M.; Bosch, F.; Boutin, D.; Chen, L.; Dimopoulou, C.; Dolinskii, A.; Franczak, B.; Franzke, B.; Geissel, H.; Hausmann, M.; Kozhuharov, C.; Kurcewicz, J.; Litvinov, S. A.; Martinez-Pinedo, G.; Matoš, M.; Mazzocco, M.; Münzenberg, G.; Nakajima, S.; Nociforo, C.; Nolden, F.; Ohtsubo, T.; Ozawa, A.; Patyk, Z.; Plaß, W. R.; Scheidenberger, C.; Stadlmann, J.; Steck, M.; Sun, B.; Suzuki, T.; Walker, P. M.; Weick, H.; Wu, M.-R.; Winkler, M.; Yamaguchi, T.

    2016-03-01

    A 410 MeV/u 238U projectile beam was used to create cadmium isotopes via abrasion-fission in a beryllium target placed at the entrance of the in-flight separator FRS at GSI. The fission fragments were separated by the FRS and injected into the isochronous storage ring ESR for mass measurements. Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without Bρ-tagging at the high-resolution central focal plane of the FRS. In the experiment with Bρ-tagging the magnetic rigidity of the injected fragments was determined with an accuracy of 2 ṡ10-4. A new method of data analysis, which uses a correlation matrix for the combined data set from both experiments, has provided experimental mass values of 25 rare isotopes for the first time. The high sensitivity and selectivity of the method have given access to nuclides detected with a rate of a few atoms per week. In this letter we present for the 129,130,131Cd isotopes mass values directly measured for the first time. The experimental mass values of cadmium as well as for tellurium and tin isotopes show a pronounced shell effect towards and at N = 82. Shell quenching cannot be deduced from a single new mass value, nor by a better agreement with a theoretical model which explicitly takes into account a quenching feature. This is in agreement with the conclusion from γ-ray spectroscopy and confirms modern shell-model calculations.

  13. Neutron beam characteristics of the prompt gamma neutron activation analysis system at HANARO

    Neutron beam characteristics of the Prompt Gamma Neutron Activation Analysis facility at HANARO were measured. The neutron beam of this facility is polychromatic thermal neutrons diffracted vertically by a set of pyrolytic graphite crystals at the Bragg angle of 45 .deg. from a horizontal beam line. Three conditions of thermal neutron extraction were applied by varying graphite crystal thickness and focusing geometry of diffracted beam. Thermal neutron profile, thermal neutron flux and Cd-ratio were measured at the sample position for each extraction condition. Thermal neutron flux of 6.1x107 n/cm2s and Cd-ratio of 364 are achieved finally

  14. Use of new composite materials for the determination of Cu, Cd, Mo, As, and Sb in biological samples by radiochemical neutron activation analysis

    Lučaníková, M.; Kučera, Jan; Šebesta, F.; John, J.

    2006-01-01

    Roč. 269, č. 2 (2006), s. 463-468. ISSN 0236-5731 R&D Projects: GA ČR(CZ) GA203/04/0943 Institutional research plan: CEZ:AV0Z10480505 Keywords : radiochemical neutron activation analysis * separation using composite materials Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.509, year: 2006

  15. Determination of As, Cd, Cr, Cu, Hg, Sb and Se concentrations by radiochemical neutron activation analysis in different Brazilian regional diets

    Radiochemical separation procedures developed for the determination of seven elements: As, Cd, Cr, Cu, Hg, Sb and Se in different Brazilian regional diets are described. In the case of the elements As, Hg, Sb and Se, the procedure was based on retention in inorganic exchanger TFO (tin dioxide) and determination of Hg by extraction with Ni(DDC)2. For determination of Cd, Cr, Cu and Se the procedure chosen was based on retention in inorganic exchanger HMD (hydrated manganese dioxide) and extraction of Cu and Cd as diethyldithiocarbamate compounds. The accuracy and precision of the methods studied were tested by means of analyses of different reference materials-Due to the lack of data on trace element levels in Brazilian foodstuffs and diets, these methods were applied to determination of these elements in different Brazilian regional diets. These s were supplied by the Food and Experimental Nutrition Department of the Faculty of Pharmaceutical Science, University of Sao Paulo. The daily intake values for these diets are presented for As, Cd, Cr, Cu, Hg, Sb and Se. (author) 21 refs.; 6 tabs

  16. Basic neutronics. Neutrons migration

    This article presents the basic neutronics necessary for the understanding of the operation of the different types of nuclear reactors: 1 - introduction to neutronics: principle of fission chain reactions, fast neutron reactors and thermal neutron reactors, capture, neutron status, variations with the reactor lattices; 2 - Boltzmann equation: neutrons population, neutrons migration, characterization of neutrons population and reactions, integral form of the Boltzmann equation, integral-differential form, equivalence between the two forms; 3 - reactor kinetics: fast neutrons and delayed neutrons, kinetic equations in punctual model, Nordheim equation, reactivity jumps, reactivity ramp; 4 - diffusion equation: local neutron status, Fick's law, diffusion equation, initial, boundary and interface conditions, nuclei in infinite and homogenous medium, some examples of solutions, developments in Eigenmodes; 5 - one-group theory: equation of the 'one-group - diffusion' theory, critical condition of the naked and homogenous reactor, critical condition of a reactor with reflectors, generalizations; 6 - neutrons moderation: different moderation mechanisms, elastic shock laws, moderation equation, some examples of solutions; 7 - resonance absorption of neutrons: advantage of the discontinuous moderation character, advantage of an heterogenous disposition, classical formula of the anti-trap factor in homogenous and heterogenous situation; 8 - neutrons thermalization: notions of thermalization mechanisms, thermalization equation, Maxwell spectrum, real spectrum, classical formula of the thermal utilisation factor, classical formula of the reproduction factor, moderation optimum. (J.S.)

  17. Experimental study of fusion neutron and proton yields produced by petawatt-laser-irradiated D2-3He or CD4-3He clustering gases

    Bang, W; Bonasera, A; Quevedo, H J; Dyer, G; Bernstein, A C; Hagel, K; Schmidt, K; Gaul, E; Donovan, M E; Consoli, F; De Angelis, R; Andreoli, P; Barbarino, M; Kimura, S; Mazzocco, M; Natowitz, J B; Ditmire, T

    2013-01-01

    We report on experiments in which the Texas Petawatt laser irradiated a mixture of deuterium or deuterated methane clusters and helium-3 gas, generating three types of nuclear fusion reactions: D(d, 3He)n, D(d, t)p and 3He(d, p)4He. We measured the yields of fusion neutrons and protons from these reactions and found them to agree with yields based on a simple cylindrical plasma model using known cross sections and measured plasma parameters. Within our measurement errors, the fusion products were isotropically distributed. Plasma temperatures, important for the cross sections, were determined by two independent methods: (1) deuterium ion time-of-flight, and (2) utilizing the ratio of neutron yield to proton yield from D(d, 3He)n and 3He(d, p)4He reactions, respectively. This experiment produced the highest ion temperature ever achieved with laser-irradiated deuterium clusters.

  18. Neutron monitoring using moderating sphere detectors

    Three moderating sphere-detector systems are examined as a neutron area monitoring instruments. The thermal neutron detectors used are the (bare-Cd covered) Li6 (Eu) crystal scintillating detector, the U235-mica track detector and the partially Cd-covered R.M. film. The response of the 12 s sphere-detector systems to Pu-Be neutrons are found to be 0.22 counts/neutrons for the Li6I-system. 8x10-4 tracks per neutron for the track-detector system and 10 mR equivalent γ-ray exposure per 2x10-neutrons per cm- for the Cd-covered R.M. film system

  19. Neutron radiography using neutron imaging plate.

    Chankow, Nares; Punnachaiya, Suvit; Wonglee, Sarinrat

    2010-01-01

    The aims of this research are to study properties of a neutron imaging plate (NIP) and to test it for use in nondestructive testing (NDT) of materials. The experiments were carried out by using a BAS-ND 2040 Fuji NIP and a neutron beam from the Thai Research Reactor TRR-1/M1. The neutron intensity and Cd ratio at the specimen position were approximately 9x10(5) ns/cm(2) s and 100 respectively. It was found that the photostimulated luminescence (PSL) readout of the imaging plate was directly proportional to the exposure time and approximately 40 times faster than the conventional NR using Gd converter screen/X-ray film technique. The sensitivities of the imaging plate to slow neutron and to Ir-192 gamma-rays were found to be approximately 4.2x10(-3) PSL/mm(2) per neutron and 6.7x10(-5) PSL/mm(2) per gamma-ray photon respectively. Finally, some specimens containing light elements were selected to be radiographed with neutrons using the NIP and the Gd converter screen/X-ray film technique. The image quality obtained from the two recording media was found to be comparable. PMID:19828321

  20. Neutron radiography using neutron imaging plate

    The aims of this research are to study properties of a neutron imaging plate (NIP) and to test it for use in nondestructive testing (NDT) of materials. The experiments were carried out by using a BAS-ND 2040 Fuji NIP and a neutron beam from the Thai Research Reactor TRR-1/M1. The neutron intensity and Cd ratio at the specimen position were approximately 9x105 ns/cm2 s and 100 respectively. It was found that the photostimulated luminescence (PSL) readout of the imaging plate was directly proportional to the exposure time and approximately 40 times faster than the conventional NR using Gd converter screen/X-ray film technique. The sensitivities of the imaging plate to slow neutron and to Ir-192 gamma-rays were found to be approximately 4.2x10-3 PSL/mm2 per neutron and 6.7x10-5 PSL/mm2 per gamma-ray photon respectively. Finally, some specimens containing light elements were selected to be radiographed with neutrons using the NIP and the Gd converter screen/X-ray film technique. The image quality obtained from the two recording media was found to be comparable.

  1. Neutron Beam Characterization for Neutron Radiography Facility at the Thai Research Reactor TRR-1/M1

    The aim of this research is to characterize the present status of neutron beam coming out from the reactor core of Thai Research Reactor TRR-1/M1 through neutron radiography facility. In this study, the neutron beam profiles at different positions along the beam exit were recorded using digital imaging devices. In addition, thin foil activation technique, with and without cadmium cover, was employed to determine thermal neutron flux and Cd ratio. An acrylic step wedge was exposed to neutron at different time. In parallel to image construction, neutron detection was carried out using a BF3 gas-filled detector. Then, the image intensities at particular thicknesses were normalized by neutron counts from the BF3 detector to determine relative neutron intensity. The obtained information of neutron beam characterization will be useful not only for monitoring the present status of neutron radiography facility but also for determining the optimum exposure conditions for particular samples in the future.

  2. CD163

    Moestrup, Søren K; Møller, Holger J

    2004-01-01

    acute phase response, there is evidence that this metabolic pathway regulates inflammation by at least two ways. First, CD163 is reported to directly induce intracellular signaling leading to secretion of anti-inflammatory cytokines. Second and perhaps even more important, the CD163-mediated delivery of......CD163 is a hemoglobin scavenger receptor exclusively expressed in the monocyte-macrophage system. A particularly high expression is seen in macrophages of the 'alternative activation' phenotype playing a major role in dampening the inflammatory response and in scavenging components of damaged cells....... CD163-mediated endocytosis of haptoglobin-hemoglobin complexes formed upon red blood cell hemolysis leads to lysosomal degradation of the ligand protein and metabolism of heme by cytosolic heme oxygenase. In accordance with a stimulated expression of haptoglobin, CD163 and heme oxygenase-1 during the...

  3. Preliminary Study on Neutron Radiography with Several Hundred keV Fast Neutrons

    Several hundred keV fast neutron radiography (HKFNR) can be a complementary technique to common thermal neutron radiography (TNR) and several MeV fast neutron radiography (MFNR). We tested HKFNR on a 4.5 MV Van de Graaff accelerator, and the experimental results show that the spatial resolution of this technique is better than MFNR and close to TNR. Several hundred keV fast neutrons can penetrate some thermal neutron absorbers such as Cd, and it is feasible to investigate its use on some materials which are transparent to cold/thermal neutrons, such as aluminum, using this technique

  4. Neutron reflectometry

    Neutron research where reflection, refraction, and interference play an essential role is generally referred to as 'neutron optics'. The neutron wavelength, the scattering length density and the magnetic properties of the material determine the critical angle for total reflection. The theoretical background of neutron reflection, experimental methods and the interpretation of reflection data are presented. (K.A.)

  5. Neutron Radiography

    Reddy, A. R.; Rao, M. V. N.

    2012-01-01

    The field of neutron radiography with special reference to isotopic neutron radiography has been reviewed. Different components viz., sources, collimators, imaging systems are described. Various designs of neutron radiography facilities, their relative merits and demerits , the appropriateness of each design depending on the object to be radiographed, and economics of each technique are also dealt. The applications of neutron radiography are also briefly presented.

  6. Neutron Detection with Cryogenics and Semiconductors

    bell, Z.W.; Carpenter, D.A.; Cristy, S.S.; Lamberti, V.E.

    2005-03-10

    The common methods of neutron detection are reviewed with special attention paid to the application of cryogenics and semiconductors to the problem. The authors' work with LiF- and boron-based cryogenic instruments is described as well as the use of CdTe and HgI{sub 2} for direct detection of neutrons.

  7. Neutron Skins and Neutron Stars

    Piekarewicz, J

    2013-01-01

    The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ("PREX") at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in 208Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron be...

  8. Study of damages by neutron irradiation in lithium aluminates

    Lithium aluminates proposed to the production of tritium in fusion nuclear reactors, due to the thermal stability that they present as well as the behavior of the aluminium to the irradiation. As a neutron flux with profile (≅ 14 Mev) of a fusion reactor is not available. A irradiation experiment was designed in order to know the micro and nano structure damages produced by fast and thermal neutrons in two irradiation positions of the fusion nuclear reactor Triga Mark III: CT (Thermal Column) and SIFCA (System of Irradiation Fixed of Capsules). In this work samples of lithium aluminate were characterized by XRD (X-Ray Diffraction), TEM (Transmission Electron Microscopy) and SEM (Scanning Electron Microscopy). Two samples were prepared by two methods: a) coalition method and b) peroxide method. This characterization comprised original and irradiated samples. The irradiated sample amounted to 4 in total: one for each preparation method and one for each irradiation position. The object of this analysis was to correlate with the received neutron dose the damages suffered by the samples with the neutron irradiation during long periods (440 H), in their micro and nano structure aspects; in order to understand the changes as a function of the irradiation zone (with thermal and fast neutron flux) and the preparation methods of the samples and having as an antecedent the irradiation in SIFCA position by short times (2h). The obtained results are referred to the stability of γ -aluminate phase, under given conditions of irradiation and defined nano structure arrangement. They also refer to the proposals of growth mechanism and nucleation of new phases. The error associated with the measurement of neutron dose is also discussed. (Author)

  9. Neutron Radiography

    A. R. Reddy

    1982-07-01

    Full Text Available The field of neutron radiography with special reference to isotopic neutron radiography has been reviewed. Different components viz., sources, collimators, imaging systems are described. Various designs of neutron radiography facilities, their relative merits and demerits , the appropriateness of each design depending on the object to be radiographed, and economics of each technique are also dealt. The applications of neutron radiography are also briefly presented.

  10. Neutron collimator design of neutron radiography based on the BNCT facility

    For the research of CCD neutron radiography, a neutron collimator was designed based on the exit of thermal neutron of the Boron Neutron Capture Therapy (BNCT) reactor. Based on the Geant4 simulations, the preliminary choice of the size of the collimator was determined. The materials were selected according to the literature data. Then, a collimator was constructed and tested on site. The results of experiment and simulation show that the thermal neutron flux at the end of the neutron collimator is greater than 1.0×106 n/cm2/s, the maximum collimation ratio (L/D) is 58, the Cd-ratio(Mn) is 160 and the diameter of collimator end is 10 cm. This neutron collimator is considered to be applicable for neutron radiography. (authors)

  11. Radiosensitivity of CD3-CD8+CD56+ NK cells

    Vokurkova, Doris [Charles University in Prague, Faculty of Medicine in Hradec Kralove, Department of Medical Biochemistry, Simkova 870, 50038 Hradec Kralove 1 (Czech Republic); Vavrova, Jirina [University of Defence, Faculty of Military Health Sciences, Department of Radiobiology, Hradec Kralove (Czech Republic); Sinkora, Jiri [Becton Dickinson (Czech Republic); Stoklasova, Alena [Charles University in Prague, Faculty of Medicine in Hradec Kralove, Department of Medical Biochemistry, Simkova 870, 50038 Hradec Kralove 1 (Czech Republic); Blaha, Vaclav [University of Defence, Faculty of Military Health Sciences, Department of Radiobiology, Hradec Kralove (Czech Republic); Rezacova, Martina, E-mail: rezacovam@lfhk.cuni.c [Charles University in Prague, Faculty of Medicine in Hradec Kralove, Department of Medical Biochemistry, Simkova 870, 50038 Hradec Kralove 1 (Czech Republic)

    2010-10-15

    The effect of lower doses (0.5-3.0 Gy) of gamma radiation on radiosensitivity of CD3-/CD8+ NK cells subpopulation isolated from the peripheral blood of healthy volunteers was studied 48 h after the irradiation. Only a subtle increase in terms of induction of apoptosis (A+ cells), was observed in Annexin positive CD3-/CD8+ NK cells. The assessment of the relative presence of CD3{sup -}/CD8{sup +} NK cells in Annexin negative populations of lymphocytes considerably contributes to the elimination of individual variability and could be useful in biodosimetry. Living CD3-/CD8+; Annexin negative NK cells were analyzed using five-color flow cytometry 16 h after irradiation by the doses of 1-10 Gy. The study was carried out on NK cells subsets CD3-/CD8- CD16+, CD56 (dim) and CD56 (bright). NK cells characterized with their low-density expression of CD56 (dim) are more cytotoxic and express CD16. Those with high-density expression of CD56 (bright) are known for their capacity to produce cytokines following activation of monocytes but their natural cytotoxicity is low; they are classified as CD16- or CD16 (dim). A dose-depending decrease in the relative presence of CD3-/CD8+ NK cells was observed 16 h after ionizing radiation (1-10 Gy). The decrease was highly pronounced in CD56 (bright) subset of NK cells and this subpopulation was considered as the most radiosensitive one. Unfortunately, the most radiosensitive subpopulation of NK cells - CD56bright cannot be used as a biodosimetric marker due to its insufficient amount in peripheral blood.

  12. Neutron Capture and Neutron Halos

    A.Mengoni; Otsuka, T; Nakamura, T.(International Center for Elementary Particle Physics and Department of Physics, The University of Tokyo, Tokyo, Japan); Ishihara, M.

    1996-01-01

    The connection between the neutron halo observed in light neutron rich nuclei and the neutron radiative capture process is outlined. We show how nuclear structure information such as spectroscopic factors and external components of the radial wave function of loosely bound states can be derived from the neutron capture cross section. The link between the direct radiative capture and the Coulomb dissociation process is elucidated.

  13. Calibration of a special neutron dosemeter based on solid-state track detectors and fission radiators in various neutron fields

    The calibration of a personnel neutron dosemeter in different neutron fields is described. The badge-like dosemeter contains 5 detectors: polycarbonate foil (10 μm, Makrofol KG), 232Th, natural uranium, natural uranium with boron, and natural uranium with cadmium. Detector sensitivity and calibration factors have been calculated and measured in radiation fields of 252Cf fission neutrons, WWR-S reactor neutrons with and without Cd and Fe shielding, 3-MeV (d,t) generator neutrons, and 238PuBe neutrons. Measurement range and achievable accuracy are discussed from the point of view of applying the dosemeter in routine and emergency uses

  14. Analysis of ancient coins by activation with rapid neutrons and by PIXE method

    The quantitative analysis of valuable objects in archaelogical research calls for the use of strictly non-destructive methods, even on very small surfaces of the object to investigate. The analytical method used by L.A.R.N. for the determination of principal elements Cu, Sn and Pb and of trace elements As and Ag in coins have been: 1. the rapid neutron activation (14 Mev) for the analysis of Sn; 2. the PIXE (Proton-Induced X-ray Emission) technique for the surface and core measures in samples which have been sawn as Sn, Pb, Ag and As. These methods have been used to analyse the blanks of Argos supplied by the Institut d'Archeologie of the University of Louvain. (A.F.)

  15. Quadrupole collectivity in 128Cd

    The regions around shell closures, especially around doubly magic nuclei, are of major interest in nuclear structure physics, as they provide a perfect test for nuclear structure theory. The neutron-rich Cd isotopes in the region of 132Sn are only two protons away from the shell closure at Z=50 and in close proximity to the N=82 magic number. Nevertheless they show an irregular behaviour regarding the excitation energy of the first excited 2+ state. This is not reproduced by shell model calculations, which is astonishing due to the proximity of the shell closures. In order to shed light on the much discussed region around doubly magic 132Sn, a Coulomb excitation experiment of 128Cd has been performed at REX-ISOLDE, CERN. The reduced transition strength B(E2;0+gs → 2+1), which is a measure of collectivity, and the spectroscopic quadrupole moment Qs(2+1) as a measure of deformation could be determined for the first time. The results are shown as the continuation of already measured neutron-rich Cd isotopes and are compared to both beyond mean field and shell model calculations, which give different predictions for these observables.

  16. In-beam γ-ray spectroscopy of 103Cd

    Excited states of 103Cd were studied in the reaction 58Ni(50Cr,4pn)103Cd. The NORDBALL array with neutron and charged particle detectors was employed for the detection of γ rays and light evaporated particles. The level scheme of 103Cd was significantly extended. A strong cascade of E2 transitions connecting negative parity states was found. Shell model calculations were performed and positive parity excited states were interpreted in terms of neutron-particle and proton-hole excitations with respect to the doubly magic N=Z=50 core. The negative parity band was well reproduced by the total routhian surface calculations. (orig.)

  17. Neutron sources

    As neutron scattering experiments have grown more and more demanding with respect to resolution and quality, it became more and more necessary to include the neutron source itself in the design of an experimental setup. In this sense the generic representation of a neutron scattering arrangement includes the primary neutron source and the associated spectrum shifter (or moderator). In fact, the design of a modern neutron source will start from a set of users requirements and will proceed 'inwards' through a selection of the moderators (spectrum shifters) to the primary source best suited to meet these often conflicting needs. This paper aims at explaining the options source designers have to match the neutron source performance to the users' demands. (author)

  18. Neutron detector

    Stephan, Andrew C.; Jardret; Vincent D.

    2011-04-05

    A neutron detector has a volume of neutron moderating material and a plurality of individual neutron sensing elements dispersed at selected locations throughout the moderator, and particularly arranged so that some of the detecting elements are closer to the surface of the moderator assembly and others are more deeply embedded. The arrangement captures some thermalized neutrons that might otherwise be scattered away from a single, centrally located detector element. Different geometrical arrangements may be used while preserving its fundamental characteristics. Different types of neutron sensing elements may be used, which may operate on any of a number of physical principles to perform the function of sensing a neutron, either by a capture or a scattering reaction, and converting that reaction to a detectable signal. High detection efficiency, an ability to acquire spectral information, and directional sensitivity may be obtained.

  19. Neutron activation analysis in Bulgaria

    The development of instrumental neutron activation analysis (INAA) as a routine method started in 1960 with bringing into use of the experimental nuclear reactor 2 MW -IRT-2000. For the purposes of INAA the vertical channels were used. The neutron flux vary from 1 to 6x1012n/cm2s, with Cd ratio for gold of about 4,4. In one of the channels the neutron flux is additionally thermalised with grafite, in others - a pneumatic double-tube rabbit system is installed. One of the irradiation positions is equiped with 1 mm Cd shield constantly. With the pressure of the working gas (air) of 2 bar the transport time in one direction is 2,5 sec. Because of lack of special system for uniform irradiation an accuracy of 3% can be reached by use of iron monitors for long irradiations and copper monitors for use in the rabbit system. Two neutron generators are also working but the application of 14 MeV neutrons for INAA is still quite limited. The most developed are the applications of INAA in the fields of geology and paedology, medicine and biology, environment and pollution, archaeology, metallurgy, metrology and hydrology, criminology

  20. Heavy weight concrete with special mixes for neutron attenuation

    This work is concerned with the study of the attenuation properties of special mixes of magnetite concrete for fast and thermal neutrons. Investigations were carried out using a collimated beam of neutrons emitted from Pu-α-Be and Californium-252 neutron sources. The fast spectra of neutrons were measured by a scintillation spectrometer with stilbene crystal. Discrimination against undesired pulses of neutrons or gamma -rays was achieved by a zero crossover method. The thermal neutron fluxes were measured by a BF3 detector. The obtained data are displayed in the form of spectra for fast neutrons and attenuation relations for thermal neutrons.The thermal neutron fluxes were measured using bare beam and beams filtered by 113 Cd and B4 C filters to discuss the origin of thermal neutrons interacting with the concrete samples. The obtained results were also used to derive the attenuation coefficients for total thermal neutrons and for newly produced thermal neutrons resulting from neutron beams filtered by 113 Cd and B4 C in the different magnetite concrete shields of different thicknesses.

  1. Neutron collimator design of neutron radiography based on the BNCT facility

    Yang, XP; Li, YG; Peng, D; Lu, J; Zhang, GL; Zhao, H; Zhang, AW; Li, CY; Liu, WJ; Hu, T; Lv, JG

    2013-01-01

    For the research of CCD neutron radiography, a neutron collimator was designed based on the exit of thermal neutron of the Boron Neutron Capture Therapy (BNCT) reactor. Based on the Geant4 simulations, the preliminary choice of the size of the collimator was determined. The materials were selected according to the literature data. Then, a collimator was constructed and tested on site. The results of experiment and simulation show that the thermal neutron flux at the end of theneutron collimator is greater than 10^6 n/cm^2/s, the maximum collimation ratio (L/D) is 58, the Cd-ratio(Mn) is 160 and the diameter of collimator end is 10 cm. This neutron collimator is considered to be applicable for neutron radiography.

  2. Neutron dosimetry

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq 241 Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s-1 and 0,5 μSv s-1. A calibrated 50 nSv s-1 thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the 241 Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold 241 Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,α) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kVpp cm-1, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46± 0,09) 104 tracks cm-2 mSv-1 for thermal neutrons, (9±3) 102 tracks cm-2 mSV-1 for intermediate neutrons and (26±4) tracks cm-2 mSv-1 for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990's ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is sufficiently sensitive to thermal and intermediate neutrons but fast neutron monitoring ar radiological protection level

  3. Atmospheric neutrons

    Additional calibrations of the University of California double-scatter neutron and additional analysis corrections lead to the slightly changed neutron fluxes reported here. The theoretical angular distributions of Merker (1975) are in general agreement with our experimental fluxes but do not give the peaks for vertical upward and downward moving neutrons. The theoretical neutron escape current J2/sub pi/ (Merker, 1972; Armstrong et al., 1973) is in agreement with the experimental values from 10 to 100 MeV. Our experimental fluxes agree with those of the Kanbach et al. (1974) in the overlap region from 70 to 100 MeV

  4. Micromegas neutron beam monitor neutronics.

    Stephan, Andrew C; Miller, Laurence F

    2005-01-01

    The Micromegas is a type of ionising radiation detector that consists of a gas chamber sandwiched between two parallel plate electrodes, with the gas chamber divided by a Frisch grid into drift and amplification gaps. Investigators have applied it to a number of different applications, such as charged particle, X-ray and neutron detection. A Micromegas device has been tested as a neutron beam monitor at CERN and is expected to be used for that purpose at the Spallation Neutron Source (SNS) under construction in Oak Ridge, TN. For the Micromegas to function effectively as neutron beam monitor, it should cause minimal disruption to the neutron beam in question. Specifically, it should scatter as few neutrons as possible and avoid neutron absorption when it does not contribute to generating useful information concerning the neutron beam. Here, we present the results of Monte Carlo calculations of the effect of different types of wall materials and detector gases on neutron beams and suggest methods for minimising disruption to the beam. PMID:16381746

  5. Neutron dosimetry; Dosimetria de neutrons

    Fratin, Luciano

    1993-12-31

    A neutron irradiation facility was designed and built in order to establish a procedure for calibrating neutron monitors and dosemeters. A 185 GBq {sup 241} Am Be source of known is used as a reference source. The irradiation facility using this source in the air provides neutron dose rates between 9 nSv s{sup -1} and 0,5 {sup {mu}}Sv s{sup -1}. A calibrated 50 nSv s{sup -1} thermal neutron field is obtained by using a specially designed paraffin block in conjunction with the {sup 241} Am Be source. A Bonner multisphere spectrometer was calibrated, using a procedure based on three methods proposed by international standards. The unfold {sup 241} Am Be neutron spectrum was determined from the Bonner spheres data and resulted in a good agreement with expected values for fluence rate, dose rate and mean energy. A dosimetric system based on the electrochemical etching of CR-39 was developed for personal dosimetry. The dosemeter badge using a (n,{alpha}) converter, the etching chamber and high frequency power supply were designed and built specially for this project. The electrochemical etching (ECE) parameters used were: a 6N KOH solution, 59 deg C, 20 kV{sub pp} cm{sup -1}, 2,0 kHz, 3 hours of ECE for thermal and intermediate neutrons and 6 hours for fast neutrons. The calibration factors for thermal, intermediate and fast neutrons were determined for this personal dosemeter. The sensitivities determined for the developed dosimetric system were (1,46{+-} 0,09) 10{sup 4} tracks cm{sup -2} mSv{sup -1} for thermal neutrons, (9{+-}3) 10{sup 2} tracks cm{sup -2} mSV{sup -1} for intermediate neutrons and (26{+-}4) tracks cm{sup -2} mSv{sup -1} for fast neutrons. The lower and upper limits of detection were respectively 0,002 mSv and 0,6 mSv for thermal neutrons, 0,04 mSv and 8 mSv for intermediate neutrons and 1 mSv and 12 mSv for fast neutrons. In view of the 1990`s ICRP recommendations, it is possible to conclude that the personal dosemeter described in this work is

  6. Neutron gun

    The neutron gun combines a new core ion source of the cold type based on X-ray ionization and new cold type of neutron source working with core ion generation. The neutrons are formed from the impact of core ions on the negatively charged anode. Based on a new conversion function, the function of the positive anode becomes analogous to the beta-unstable decomposition of a neutron. A core ion and neutron amplifier in the sense of amplifying the number is derived from the beta-unstable neutron decomposition, in order to raise the output of a gun in pulsed operation by using the number amplification in the intervals between the pulses. The method of construction is simple and cheap, the equipment has purely linear acceleration or operation with circular acceleration with linear pre-acceleration as an alternative. Purely linear operation should be sufficient for medical applications, e.g. for neutron photography to replay X-ray photography and particularly for neutron scalpels in the surgical treatment of tumours. (orig./HP)

  7. Cadmium mass measurements between the neutron shell closures at N = 50 and 82

    The mass values of the neutron-deficient cadmium isotopes 99-109Cd and of the neutron-rich isotopes 114,120,122-124,126,128Cd have been measured using ISOLTRAP. The behavior of the separation energies of the cadmium isotopes from N = 50 to 82 is discussed.

  8. Neutron transport

    This bibliographical note presents a reference book which addresses the study of neutron transport in matter, the study of conditions for a chain reaction and the study of modifications of matter composition due to nuclear reactions. This book presents the main nuclear data, their measurement, assessment and processing, and the spallation. It proposes an overview of methods applied for the study of neutron transport: basic equations and their derived forms, deterministic methods and Monte Carlo method of resolution of the Boltzmann equation, methods of resolution of generalized Bateman equations, methods of time resolution of space kinetics coupled equations. It presents the main calculation codes, discusses the qualification and experimental aspects, and gives an overview of neutron transport applications: neutron transport calculation of reactors, neutron transport coupled with other disciplines, physics of fuel cycle, criticality

  9. Neutron tubes

    Leung, Ka-Ngo; Lou, Tak Pui; Reijonen, Jani

    2008-03-11

    A neutron tube or generator is based on a RF driven plasma ion source having a quartz or other chamber surrounded by an external RF antenna. A deuterium or mixed deuterium/tritium (or even just a tritium) plasma is generated in the chamber and D or D/T (or T) ions are extracted from the plasma. A neutron generating target is positioned so that the ion beam is incident thereon and loads the target. Incident ions cause D-D or D-T (or T-T) reactions which generate neutrons. Various embodiments differ primarily in size of the chamber and position and shape of the neutron generating target. Some neutron generators are small enough for implantation in the body. The target may be at the end of a catheter-like drift tube. The target may have a tapered or conical surface to increase target surface area.

  10. Parity-non-conserving internucleon potentials studied in the 113Cd (n, γ) 114Cd reaction

    Warming, Inge Elisabeth; Stecher-Rasmussen, F.; Ratynski, W.; Kopecky, J.

    The asymmetry in the gamma intensity after capture of polarized neutrons in 113Cd was investigated. An upper limit to a possible asymmetry A was determined of |A| <4.7 times 10-4. This result does not agree with that of Abov et al....

  11. Combination of the prompt neutron capture method with other neutron methods for substance elemental content analysis

    Neutron analysis method of determining element composition have found wide range of applications in industry thanks to different types of interaction of neutron with substances /1/. With the aim of widening the range of problems to be solved, on the basis of the device /2/ for determining the element content of substance, possibilities of combining the method based on the use of neutron capture gamma-ray spectrometry with other neutron methods, in particular neutron activation analysis and neutron absorption analysis were studied. In this radionuclide source (252Cf) with the yield of 1,5 x 107 neutron/sec is used. By means of using neutron capture gamma radiation spectrometry the possibilities of determining some elements (H, B, N, S etc. ), which are not determined by very widely used method, activation analysis. These elements can be determined by both the semiconductor and scintillation detectors with parameters fitting the manufacturing requirements. And for a number of elements ( B, Cl, Cd, Sm, Gd) very high limits of determination ( up to 10- 5 %) are possible using semiconductor Ge (Li) -detectors with high resolution. Possibility of determination of some 'well' activated elements ( K, Al, Fe, Mn, Ti, Sc etc.) in samples of ore and products of their processing using the neutron-activation analysis. For 1 hour of irradiation on the experimental device quite accurate analytical peak, of these elements are obtained, allowing to determine them qualitatively. However, with decreasing neutron yield of radionuclide source it becomes more difficult to achieve the necessary parameters both in neutron capture and activation analysis. Experimental works on determination of some elements with large cross-sections of capture ( B, Cd, Sm ) by absorption of neutrons in the investigated substance, i.e. using the neutron absorption analysis method with absence of other large capture cross section elements in the samples being studied. (author)

  12. Neutron radiography

    This introduction is addressed to an audience active in diverse forms of neutron source applications but not directly familiar with neutron radiography. Neutron radiography is, of course, similar to, and complementary to, radiography using x-rays. However, neutrons, being sensitive to the nuclear properties of materials, provide information fundamentally different from x-rays. For example, neutrons can penetrate many dense metals such as uranium, lead, bismuth or steel, and can reveal details of internal hydrogenous components: explosives, lubricants and gaskets. For nuclear fuel inspection neutron radiography offers the ability to penetrate dense uranium-238 and contrast the isotopes U-235 or Pu-239 and also offers the ability to discriminate against unwanted interference from gamma radiation. In addition to advantages in industrial applications, there are special situations in fields such as medical diagnostics, dentistry, agriculture and forensic science. Comprehensive accounts of applications in the field can be found in the proceedings of the world conferences on neutron radiography: USA (1981), FRANCE (1986). A third conference in this series is scheduled for May 1989 in Japan

  13. Neutron radiography

    The digital processing of the neutron radiography images gives the possibility for data quantification. In this case an exact relation between the measured neutron attenuation and the real macroscopic attenuation coefficient for every point of the sample is required. The assumption that the attenuation of the neutron beam through the sample is exponential is valid only in an ideal case where a monochromatic beam, non scattering sample and non background contribution are assumed. In the real case these conditions are not fulfilled and in dependence on the sample material we have more or less deviation from the exponential attenuation law. Because of the high scattering cross-sections of hydrogen (σs=80.26 barn) for thermal neutrons, the problem with the scattered neutrons at quantitative radiography investigations of hydrogenous materials (as PE, Oil, H2O, etc) is not trivial. For these strong scattering materials the neutron beam attenuation is no longer exponential and a dependence of the macroscopic attenuation coefficient on the material thickness and on the distance between the sample and the detector appears. When quantitative radiography (2 D) or tomography investigations (3 D) are performed, some image correction procedures for a description of the scattering effect are required. This thesis presents a method that can be used to enhance the neutron radiography image for objects with high scattering materials like hydrogen, carbon and other light materials. This method uses the Monte Carlo code, MCNP5, to simulate the neutron radiography process and get the flux distribution for each pixel of the image and determine the scattered neutrons distribution that causes the image blur and then subtract it from the initial image to improve its quality.

  14. Neutron tomography

    In this paper a survey is given of recent developments in selected areas of neutron tomography, within the context of several applications Argonne is involved in, including high penetration of reactor-fuel bundles in thick containers (involving TREAT and NRAD facilities), dual-energy hydrogen imaging (performed at IPNS), dynamic coarse-resolution emission tomography of rector fuel under test (a proposed modification to the TREAT hodoscope), and an associated-particle system that uses neutron flight-time to electronically collimate transmitted neutrons and to tomographically image nuclides identified by reaction gamma-rays

  15. TLD determination of neutron dose contribution in medical linac

    The increased use of Linacs with accelerating voltage higher than 10 MV in clinical radiotherapy is producing and increasing demand of accurate dosimetric measurements of the photon induced neutron contamination of the radiotherapy beams, due that the associated Bremsstrahlung X rays may produce neutrons as a result of subsequent photonuclear reactions with the different materials constituting the accelerator head. Thermal neutron fluences can be measured with TLD-600/TLD-700 pairs arranged in both a bare and a cadmium (Cd) foil covered methacry-late box. Neutron response of Tl dosemeters irradiated with two different neutron sources has been investigated. The shape of the glow curve of these TLDs after irradiation in a medical Linac and in a Pu Be neutron source has been studied to verify the contribution of neutrons to an additional dose to staff, patients and the general public, due to photonuclear reactions generating neutrons from medical Linacs. (Author)

  16. Levels structures of Cd-114

    The level structures of 114Cd up to an excitation energy of 3.6 MeV have been investigated. Gamma radiation following thermal neutron capture in 113Cd in the energy region from 50 keV to 2.2 MeV has been measured by means of the three curved-crystal γ-ray spectrometers, GAMS 1 and GAMS 2/3 at the I.L.L. reactor. Internal conversion electrons have been measured with the electron spectrometer BILL installed at the I.L.L. Several targets were prepared by the evaporation or sedimentation technique in order to measure the electrons in the energy region from 40 keV to 8.5 MeV. Multipolarities for a large number of transitions were determined. Primary γ-ray following average resonance neutron capture at Esub(n) = 2 keV and 24 keV were recorded at the Brookhaven National Laboratory resulting in a complete set of levels with Isup(π) +- up to 3 MeV excitation energy. Combining these results a level scheme up to 3.6 MeV has been constructed

  17. Neutron scattering

    This report contains the text of 16 lectures given at the Summer School and the report on a panel discussion entitled ''the relative merits and complementarities of x-rays, synchrotron radiation, steady- and pulsed neutron sources''. figs., tabs., refs

  18. Piezonuclear Neutrons

    Cardone, Fabio; Petrucci, Andrea

    2008-01-01

    We report the results of neutron measurements carried out during the application of ultrasounds to a solution containing only stable elements like Iron and Chlorine, without any other radioactive source of any kind. These measurements, carried out by CR39 detectors and a Boron TriFouride electronic detector, evidenced the emission of neutron pulses. These pulses stand well above the electronic noise and the background of the laboratory where the measurements were carried out.

  19. Neutron Scattering

    The neutron probe is a standard tool for measuring soil water content. This article provides an overview of the underlying theory, describes the methodology for its calibration and use, discusses example applications, and identifies the safety issues. Soil water makes land-based life possible by satisfying plant water requirements, serving as a medium for nutrient movement to plant roots and nutrient cycling, and controlling the fate and transport of contaminants in the soil environment. Therefore, a successful understanding of the dynamics of plant growth, nutrient cycling, and contaminant behavior in the soil requires knowledge of the soil water content as well as its spatial and temporal variability. After more than 50 years, neutron probes remain the most reliable tool available for field monitoring of soil water content. Neutron probes provide integrated measurements over relatively large volumes of soil and, with proper access, allow for repeated sampling of the subsurface at the same locations. The limitations of neutron probes include costly and time-consuming manual operation, lack of data automation, and costly regulatory requirements. As more non-radioactive systems for soil water monitoring are developed to provide automated profiling capabilities, neutron-probe usage will likely decrease. Until then, neutron probes will continue to be a standard for reliable measurements of field water contents in soils around the globe

  20. FOREWORD: Neutron metrology Neutron metrology

    Thomas, David J.; Nolte, Ralf; Gressier, Vincent

    2011-12-01

    The International Committee for Weights and Measures (CIPM) has consultative committees covering various areas of metrology. The Consultative Committee for Ionizing Radiation (CCRI) differs from the others in having three sections: Section (I) deals with radiation dosimetry, Section (II) with radionuclide metrology and Section (III) with neutron metrology. In 2003 a proposal was made to publish special issues of Metrologia covering the work of the three Sections. Section (II) was the first to complete their task, and their special issue was published in 2007, volume 44(4). This was followed in 2009 by the special issue on radiation dosimetry, volume 46(2). The present issue, volume 48(6), completes the trilogy and attempts to explain neutron metrology, the youngest of the three disciplines, the neutron only having been discovered in 1932, to a wider audience and to highlight the relevance and importance of this field. When originally approached with the idea of this special issue, Section (III) immediately saw the value of a publication specifically on neutron metrology. It is a topic area where papers tend to be scattered throughout the literature in journals covering, for example, nuclear instrumentation, radiation protection or radiation measurements in general. Review articles tend to be few. People new to the field often ask for an introduction to the various topics. There are some excellent older textbooks, but these are now becoming obsolete. More experienced workers in specific areas of neutron metrology can find it difficult to know the latest position in related areas. The papers in this issue attempt, without presenting a purely historical outline, to describe the field in a sufficiently logical way to provide the novice with a clear introduction, while being sufficiently up-to-date to provide the more experienced reader with the latest scientific developments in the different topic areas. Neutron radiation fields obviously occur throughout the nuclear

  1. Neutron activation analysis of cadmium in Jamaican soils

    A procedure for the instrumental neutron activation analysis of Cd in soils with relatively high Cd content and possible interferences is reported. Cadmium concentrations in Jamaican soils above 4 mg x kg-1 can now be reliably determined by multielemental instrumental activation analysis with an accuracy ±10% and the reasonably high throughput of 30 samples per day. Over 600 geochemical survey samples were analysed for Cd along with some 20 other long-lived elements. (author)

  2. Multi particle excitations in 102Cd

    The structure of nuclei belonging to A ∼100 mass region are interesting to study because of the dominating shell closure effects. The even-even transitional nucleus 102Cd with 48 protons and 54 neutrons is close to the doubly magic 100Sn with N=Z=50. Its structure may follow the shell model or it may possibly develop collective features since it has sufficiently large number of valence nucleons outside the 100Sn core. The distinct pattern of proton and neutron excitations at low spins may align to contribute to the total angular momentum at high spin giving rise to magnetic rotation. However, the lack of firm spin parity assignment and absolute transition strengths, the interpretation of high spin states in 102Cd is very tentative. This mechanism is characterised by a pronounced decrease in magnetic dipole transition strength B(M1) as the shears vectors close. Such behaviour may be proved from lifetime measurements

  3. Producing CD-ROMs.

    Hyams, Peter, Ed.

    1992-01-01

    This issue presents 11 articles that address issues relating to the production of CD-ROMs. Highlights include current uses of CD-ROM; standards; steps involved in producing CD-ROMs, including data capture, conversion, and tagging, product design, and indexing; authoring; selecting indexing and retrieval software; costs; multimedia CD-ROMs; and…

  4. Cadmium Subtraction Method for the Active Albedo Neutron Interrogation of Uranium

    Worrall, Louise G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Croft, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-02-01

    This report describes work performed under the Next Generation Safeguards Initiative (NGSI) Cadmium Subtraction Project. The project objective was to explore the difference between the traditional cadmium (Cd) ratio signature and a proposed alternative Cd subtraction (or Cd difference) approach. The thinking behind the project was that a Cd subtraction method would provide a more direct measure of multiplication than the existing Cd ratio method. At the same time, it would be relatively insensitive to changes in neutron detection efficiency when properly calibrated. This is the first published experimental comparison and evaluation of the Cd ratio and Cd subtraction methods.

  5. Probing the quadrupole collectivity of 128Cd using Coulomb excitation

    128Cd is only two proton and two neutron holes away from the doubly magic nucleus 132Sn. The excitation energy of the first excited 2+-state decreases when approaching the neutron shell closure. This unexpected behaviour makes this nucleus interesting for investigation. So far, contradicting theoretical predictions for the B(E2,0+ → 2+) value of 128Cd exist. While shell model calculations conclude an almost spherical shape of 128Cd, beyond mean field calculations predict an already considerable quadrupole collectivity. In this contribution the experimental details of the Coulomb excitation of 128Cd at REX-ISOLDE, investigated with MINIBALL (experiment IS477), are presented. Furthermore the current status of the analysis to determine the transition strength of the ground state into the first excited 2+ state is shown.

  6. Neutron Repulsion

    Manuel, Oliver K

    2011-01-01

    Earth is connected gravitationally, magnetically and electrically to its heat source - a neutron star that is obscured from view by waste products in the photosphere. Neutron repulsion is like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the solar core and decay into hydrogen that glows in the photosphere like a frosted light bulb. Neutron repulsion was recognized in nuclear rest mass data in 2000 as the overlooked source of energy, the keystone of an arch that locked together these puzzling space-age observations: 1.) Excess 136Xe accompanied primordial helium in the stellar debris that formed the solar system (Fig. 1); 2.) The Sun formed on the supernova core (Fig. 2); 3.) Waste products from the core pass through an iron-rich mantle, selectively carrying lighter elements and lighter isotopes of each element into the photosphere (Figs. 3-4); and 4.) Neutron repulsion powers the Sun and sustains life (Figs. 5-7). Together these findings offer a framework for understanding...

  7. neutron radiography

    Neutron radiography (or radiology) is a diverse filed that uses neutrons of various energies, subthermal, thermal, epithermal or fast in either steady state or pulsed mode to examine objects for industrial, medical, or other purposes, both microscopic and macroscopic. The applications include engineering design, biological studies, nondestructive inspection and materials evaluation. In the past decade, over 100 different centers in some 30 countries have published reports of pioneering activities using reactors, accelerators and isotopic neutron sources. While film transparency and electronic video are most common imaging methods for static or in motion objects respectively, there are other important data gathering techniques, including track etch, digital gauging and computed tomography. A survey of the world-wide progress shows the field to be gaining steadily in its diversity, its sophistication and its importance. (author)

  8. The Qβ values of the heavy Cd and In isotopes

    The total decay energies of neutron rich isotopes of Cd and In have been determined using end-points of β-spectra recorded in a βγ-coincidence experiment. The data have been used to deduce the first experimental nuclear masses for 123-128Cd and have given improved mass values for 123-130In. A comparison is made with the predictions of several mass formulae. (orig.)

  9. Neutron diffraction

    Heger, G. [Rheinisch-Westfaelische Technische Hochschule Aachen, Inst. fuer Kristallographie, Aachen (Germany)

    1996-12-31

    X-ray diffraction using conventional laboratory equipment and/or synchrotron installations is the most important method for structure analyses. The purpose of this paper is to discuss special cases, for which, in addition to this indispensable part, neutrons are required to solve structural problems. Even though the huge intensity of modern synchrotron sources allows in principle the study of magnetic X-ray scattering the investigation of magnetic structures is still one of the most important applications of neutron diffraction. (author) 15 figs., 1 tab., 10 refs.

  10. Regulatory function of cytomegalovirus-specific CD4+CD27-CD28- T cells

    CMV infection is characterized by high of frequencies of CD27-CD28- T cells. Here we demonstrate that CMV-specific CD4+CD27-CD28- cells are regulatory T cells (TR). CD4+CD27-CD28- cells sorted from CMV-stimulated PBMC of CMV-seropositive donors inhibited de novo CMV-specific proliferation of autologous PBMC in a dose-dependent fashion. Compared with the entire CMV-stimulated CD4+ T-cell population, higher proportions of CD4+CD27-CD28- TR expressed FoxP3, TGFβ, granzyme B, perforin, GITR and PD-1, lower proportions expressed CD127 and PD1-L and similar proportions expressed CD25, CTLA4, Fas-L and GITR-L. CMV-CD4+CD27-CD28- TR expanded in response to IL-2, but not to CMV antigenic restimulation. The anti-proliferative effect of CMV-CD4+CD27-CD28- TR significantly decreased after granzyme B or TGFβ inhibition. The CMV-CD4+CD27-CD28- TR of HIV-infected and uninfected donors had similar phenotypes and anti-proliferative potency, but HIV-infected individuals had higher proportions of CMV-CD4+CD27-CD28- TR. The CMV-CD4+CD27-CD28- TR may contribute to the downregulation of CMV-specific and nonspecific immune responses of CMV-infected individuals.

  11. Neutron reflectometer

    The neutron reflectometer is the most powerful and nondestructive tool to analyze the surface and buried interfaces in the layered films. Such films often have a close relation to the functional devices. Structural information in the vicinity of the interfaces is a key parameter in the field of the nanoscale science. (author)

  12. Neutron radiography

    Principles of the method, complementarity with X or gamma rays, neutron energy, detection and applications on irradiated materials and for the industrial quality control are exposed. Examples of applications in pyrotechnics, plastics, fuels, lubricants, metallurgy are given. Techniques developed by the CEA for its own needs or for industry and description of facilities in the nuclear centers are reviewed

  13. Physical engineering for boron neutron capture therapy in KUR

    Kobayashi, Toru [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst

    2001-01-01

    Basic results of physical engineering study for neutron capture therapy in KUR have been reported since 1970, such as (1) development of thermal neutron fields for therapy following with low {gamma}-ray, (2) development of thermal neutron shield material ({sup 6}LiF) following with low secondary {gamma}-ray, (3) establishment of measurement techniques for B-10 concentration in tissue by using then (n,{gamma}) reaction, (4) evaluation of absorbed dose in a cell level during neutron capture therapy. It is difficult for many of thermal neutrons to reach to the depths in tissue. The thermal neutron irradiation, therefore, is suitable for the therapy of cancer on surface tissue, but not suitable for the therapy of cancer in the depths. Uses of epi-thermal (0.5 eV - 10 keV) or hyper-thermal (>0.5 eV) neutrons, instead of thermal neutron are considered for the neutron capture therapy to cancer in the depth. The depth dose distributions of thermal neutron are improved by increase of forward component of the epi-thermal or the hyper-thermal neutron. Thermal neutron fluxes have been measured by the activation method of Au-197. Thermo-luminescent detector (MgSiO4, or BeO) is used for the measurement of {gamma}-ray doses. Noninvasive dose estimation at cancer parts is developed with a prompt {gamma}-ray analysis method using HPGe and CdTe semiconductor detectors. (Suetake, M.)

  14. Neutron absorbers and detector types for spent fuel verification using the self-interrogation neutron resonance densitometry

    The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive non-destructive assay (NDA) technique that is proposed for the direct measurement of 239Pu in a spent fuel assembly. The insertion of neutron detectors wrapped with different neutron absorbing materials, or neutron filters, in the central guide tube of a PWR fuel assembly is envisaged to measure the neutron flux in the energy region close to the 0.3 eV resonance of 239Pu. In addition, the measurement of the fast neutron flux is foreseen. This paper is focused on the determination of the Gd and Cd neutron filters thickness to maximize the detection of neutrons within the resonance region. Moreover, several detector types are compared to identify the optimal condition and to assess the expected total neutron counts that can be obtained with the SINRD measurements. Results from Monte Carlo simulations showed that ranges between 0.1–0.3 mm and 0.5–1.0 mm ensure the optimal conditions for the Gd and Cd filters, respectively. Moreover, a 239Pu fission chamber is better suited to measure neutrons close to the 0.3 eV resonance and it has the highest sensitivity to 239Pu, in comparison with a 235U fission chamber, with a 3He proportional counter, and with a 10B proportional counter. The use of a thin Gd filter and a thick Cd filter is suggested for the 239Pu and 235U fission chambers to increase the total counts achieved in a measurement, while a thick Gd filter and a thin Cd filter are envisaged for the 3He and 10B proportional counters to increase the sensitivity to 239Pu. We concluded that an optimization process that takes into account measurement time, filters thickness, and detector size is needed to develop a SINRD detector that can meet the requirement for an efficient verification of spent fuel assemblies

  15. Methods for absorbing neutrons

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  16. Investigation of neutron-deficient isotopes in the barium-region

    Bombarding targets of 106Cd, 108Cd and 110Cd with 16O ions of 52.5-66.0 MeV neutron deficient barium, cesium and xenon isotopes were produced and have been studied using excitation functions and neutron-gamma, proton-gamma, alpha-gamma and gamma-gamma coincidence measurements. Partial level schemes for 123Ba and 121Ba were proposed. A number of gamma transitions was assigned to the different product nuclei. The measured particle emission probabilities from the compound nuclei are compared with different evaporation models. The models mostly underestimate neutron emission and often overestimate the emission of alpha particles. (orig.)

  17. Neutron activation analysis of reference materials

    The importance is pointed out of neutron activation analysis in the preparation of reference materials, and studies are reported conducted recently by UJV. Instrumental neutron activation analysis has been used in testing homogeneity and in determining 28 elements in newly prepared reference standards of coal fly ash designated ENO, EOP and ECH. For accuracy testing, the same method was used in the analysis of NBS SRM-1633a Trace Elements in Coal Fly Ash and IAEA CRM Soil-5 and RM Soil-7. Radiochemical neutron activation analysis was used in determining Cd, Cu, Mn, Mo, and Zn in biological materials NBS SRM-1577 Bovine Liver, Bowen's Kale and in IAEA RM Milk Powder A-11 and Animal Muscle H-4. In all instances very good precision and accuracy of neutron activation analysis results were shown. (author)

  18. Recent Advances in Neutron Physics

    Feshbach, Herman; Sheldon, Eric

    1977-01-01

    Discusses new studies in neutron physics within the last decade, such as ultracold neutrons, neutron bottles, resonance behavior, subthreshold fission, doubly radiative capture, and neutron stars. (MLH)

  19. Neutron rich nuclei and neutron stars

    Horowitz, C. J.

    2013-01-01

    The PREX experiment at Jefferson Laboratory measures the neutron radius of 208Pb with parity violating electron scattering in a way that is free from most strong interaction uncertainties. The 208Pb radius has important implications for neutron rich matter and the structure of neutron stars. We present first PREX results, describe future plans, and discuss a follow on measurement of the neutron radius of 48Ca. We review radio and X-ray observations of neutron star masses and radii. These cons...

  20. Photodissociation of neutron deficient nuclei

    Sonnabend, K.; Babilon, M.; Hasper, J.; Mueller, S.; Zarza, M.; Zilges, A. [TU Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany)

    2006-03-15

    The knowledge of the cross sections for photodissociation reactions like e.g. ({gamma}, n) of neutron deficient nuclei is of crucial interest for network calculations predicting the abundances of the so-called p nuclei. However, only single cross sections have been measured up to now, i.e., one has to rely nearly fully on theoretical predictions. While the cross sections of stable isotopes are accessible by experiments using real photons, the bulk of the involved reactions starts from unstable nuclei. Coulomb dissociation (CD) experiments in inverse kinematics might be a key to expand the experimental database for p-process network calculations. The approach to test the accuracy of the CD method is explained. (orig.)

  1. Photodissociation of neutron deficient nuclei

    Sonnabend, K.; Babilon, M.; Hasper, J.; Müller, S.; Zarza, M.; Zilges, A.

    2006-03-01

    The knowledge of the cross sections for photodissociation reactions like e.g. (γ, n) of neutron deficient nuclei is of crucial interest for network calculations predicting the abundances of the so-called p nuclei. However, only single cross sections have been measured up to now, i.e., one has to rely nearly fully on theoretical predictions. While the cross sections of stable isotopes are accessible by experiments using real photons, the bulk of the involved reactions starts from unstable nuclei. Coulomb dissociation (CD) experiments in inverse kinematics might be a key to expand the experimental database for p-process network calculations. The approach to test the accuracy of the CD method is explained.

  2. Neutron dosimetry

    It is the object of the present invention to provide a method of measuring neutron radiation which eliminates the use of powders as dosimeter target materials and reduces the requirement for repetitive weighing of dosimeters, for expensive radioisotopes as dosimeter target material, and for dosimeter housings (in many cases). The invention described is a method of measuring neutron radiation within a nuclear reactor consisting of placing one or more extruded sintered oxide wires comprising a dosimeter target oxide within the reactor and measuring the radioactivity induced in the wires by neutron radiation. These oxide wires consist of a dilution containing at least 0.1% by weight of the dosimeter target oxide in a diluent oxide. The diluent oxide is selected from a group consisting of Al2O3 and BeO. Almost any metal oxide may be used as a target oxide. The wires may be encapsulated within a co-extruded housing. These mixed oxide wires have been found to be sufficiently uniform for quantitative analyses. (JTA)

  3. Neutron scattering

    The annual report on hand gives an overview of the research work carried out in the Laboratory for Neutron Scattering (LNS) of the ETH Zuerich in 1990. Using the method of neutron scattering, it is possible to examine in detail the static and dynamic properties of the condensed material. In accordance with the multidisciplined character of the method, the LNS has for years maintained a system of intensive co-operation with numerous institutes in the areas of biology, chemistry, solid-state physics, crystallography and materials research. In 1990 over 100 scientists from more than 40 research groups both at home and abroad took part in the experiments. It was again a pleasure to see the number of graduate students present, who were studying for a doctorate and who could be introduced into the neutron scattering during their stay at the LNS and thus were in the position to touch on central ways of looking at a problem in their dissertation using this modern experimental method of solid-state research. In addition to the numerous and interesting ways of formulating the questions to explain the structure, nowadays the scientific programme increasingly includes particularly topical studies in connection with high temperature-supraconductors and materials research

  4. Neutron scattering. Lectures

    The following topics are dealt with: Neutron sources, symmetry of crystals, nanostructures investigated by small-angle neutron scattering, structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic neutron scattering, strongly correlated electrons, polymer dynamics, applications of neutron scattering. (HSI)

  5. Neutron scattering. Lectures

    The following topics are dealt with: Neutron scattering in contemporary research, neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  6. CD3(+)CD8(+)CD28(-) T Lymphocytes in Patients with Lupus Nephritis.

    Żabińska, Marcelina; Krajewska, Magdalena; Kościelska-Kasprzak, Katarzyna; Klinger, Marian

    2016-01-01

    The results of studies on the CD3(+)CD8(+)CD28(-) cells in SLE are inconsistent since several analyses describe CD3(+)CD8(+)CD28(-) as either immunosuppressive or cytotoxic. The aim of this study is to inquire whether the quantitative changes of CD3(+)CD8(+)CD28(-) T lymphocytes subpopulation are related to the clinical status of patients with lupus nephritis. Evaluation of Foxp3 expression on CD3(+)CD8(+)CD28(-) cells may shed some light on functional properties of these cells. 54 adult SLE patients and 19 sex and age matched healthy volunteers were enrolled in the study. There were 15 patients in inactive (SLEDAI ≤ 5) and 39 in active (SLEDAI > 5) phase of disease. We determined absolute count of CD3(+)CD8(+)CD28(-) and CD3(+)CD8(+)CD28(-)Foxp3(+) subpopulations by flow cytometry. We observed a statistically significant increase in absolute count and percentage of CD3(+)CD8(+)CD28(-) in SLE patients compared to HC (p < 0.001). Moreover there was significant positive correlation between increasing absolute count of CD3(+)CD8(+)CD28(-) cells and disease activity measured by SLEDAI (rs = 0.281, p = 0.038). Active LN patients had increased absolute count of CD3(+)CD8(+)CD28(-) cells compared to HC. Positive correlation of CD3(+)CD8(+)CD28(-) number with disease activity, and lack of Foxp3 expression on these cells, suggests that CD3(+)CD8(+)CD28(-) lymphocytes might be responsible for an increased proinflammatory response in the exacerbation of SLE. PMID:27446964

  7. Study of damages by neutron irradiation in lithium aluminates; Estudio de danos por irradiacion neutronica en aluminatos de litio

    Palacios G, O

    1999-06-01

    Lithium aluminates proposed to the production of tritium in fusion nuclear reactors, due to the thermal stability that they present as well as the behavior of the aluminium to the irradiation. As a neutron flux with profile ({approx_equal} 14 Mev) of a fusion reactor is not available. A irradiation experiment was designed in order to know the micro and nano structure damages produced by fast and thermal neutrons in two irradiation positions of the fusion nuclear reactor Triga Mark III: CT (Thermal Column) and SIFCA (System of Irradiation Fixed of Capsules). In this work samples of lithium aluminate were characterized by XRD (X-Ray Diffraction), TEM (Transmission Electron Microscopy) and SEM (Scanning Electron Microscopy). Two samples were prepared by two methods: a) coalition method and b) peroxide method. This characterization comprised original and irradiated samples. The irradiated sample amounted to 4 in total: one for each preparation method and one for each irradiation position. The object of this analysis was to correlate with the received neutron dose the damages suffered by the samples with the neutron irradiation during long periods (440 H), in their micro and nano structure aspects; in order to understand the changes as a function of the irradiation zone (with thermal and fast neutron flux) and the preparation methods of the samples and having as an antecedent the irradiation in SIFCA position by short times (2h). The obtained results are referred to the stability of {gamma} -aluminate phase, under given conditions of irradiation and defined nano structure arrangement. They also refer to the proposals of growth mechanism and nucleation of new phases. The error associated with the measurement of neutron dose is also discussed. (Author)

  8. Influence of thermal and resonance neutron on fast neutron flux measurement by Pu-239 fission chamber

    zeng, Lina; Song, Lingli; Zheng, Chun

    2014-01-01

    The Pu-239 fission chambers are widely used to measure fission spectrum neutron flux due to a flat response to fast neutrons. However, in the mean time the resonance and thermal neutrons can cause a significant influence on the measurement if they are moderated, which could be eliminated by using B and Cd covers. At a column enriched uranium fast neutron critical assembly, the fission reaction rates of Pu-239 are measured as 1.791*10-16,2.350*10-16 and 1.385*10-15 per second for 15mm thick B cover, 0.5mm thick Cd cover, and no cover respectively. While the fission reaction rate of Pu-239 is rapidly increased to 2.569*10-14 for a 20mm thick polythene covering fission chamber. The average Pu-239 fission cross-section of thermal and resonance neutrons is calculated to be 500b and 24.95b with the assumption of 1/v and 1/E spectra respectively, then thermal, resonance and fast neutron flux are achieved to be 2.30*106,2.24*106 and 1.04*108cm-2s-1.

  9. Quadrupole collectivity in {sup 128}Cd

    Boenig, Esther Sabine

    2014-07-07

    The regions around shell closures, especially around doubly magic nuclei, are of major interest in nuclear structure physics, as they provide a perfect test for nuclear structure theory. The neutron-rich Cd isotopes in the region of {sup 132}Sn are only two protons away from the shell closure at Z=50 and in close proximity to the N=82 magic number. Nevertheless they show an irregular behaviour regarding the excitation energy of the first excited 2{sup +} state. This is not reproduced by shell model calculations, which is astonishing due to the proximity of the shell closures. In order to shed light on the much discussed region around doubly magic {sup 132}Sn, a Coulomb excitation experiment of {sup 128}Cd has been performed at REX-ISOLDE, CERN. The reduced transition strength B(E2;0{sup +}{sub gs} → 2{sup +}{sub 1}), which is a measure of collectivity, and the spectroscopic quadrupole moment Q{sub s}(2{sup +}{sub 1}) as a measure of deformation could be determined for the first time. The results are shown as the continuation of already measured neutron-rich Cd isotopes and are compared to both beyond mean field and shell model calculations, which give different predictions for these observables.

  10. Spallation Neutron Source (SNS)

    Federal Laboratory Consortium — The SNS at Oak Ridge National Laboratory is a next-generation spallation neutron source for neutron scattering that is currently the most powerful neutron source in...

  11. Design of an epi-thermal neutron flux intensity monitor with GaN wafer for boron neutron capture therapy

    Boron neutron capture therapy (BNCT) is a promising cancer therapy. Epi-thermal neutron (0.5 eV < En < 10 keV) flux intensity is one of the basic characteristics for modern BNCT. In this work, based on the 71Ga(n, γ)72Ga reaction, a new simple monitor with gallium nitride (GaN) wafer as activation material was designed by Monte Carlo simulations to precisely measure the absolute integral flux intensity of epi-thermal neutrons especially for practical BNCT. In the monitor, a GaN wafer was positioned in the center of a polyethylene sphere as neutron moderator covered with cadmium (Cd) layer as thermal neutron absorber outside. The simulation results and related analysis indicated that the epi-thermal neutron flux intensity could be precisely measured by the presently designed monitor. (author)

  12. The crystal structure analysis of deuterated benzene and deuterated nitromethane by pulsed-neutron powder diffraction: a comparison with single crystal neutron diffraction analysis

    The results of time-of-flight neutron powder diffraction analyses at 4.2 K are compared with those from steady-state neutron single-crystal analyses at 15 K for deuterated benzene, C6D6, and deuteronitromethane, CD3NO2. (orig.)

  13. Neutron scattering. Lectures

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  14. REFRACTIVE NEUTRON LENS

    Petrov, P. V.; Kolchevsky, N.N.

    2013-01-01

    Compound concave refractive lenses are used for focusing neutron beam. Investigations of spectral and focusing properties of a refractive neutron lens are presented. Resolution of the imaging system on the base of refractive neutron lenses depends on material properties and parameters of neutron source. Model of refractive neutron lens are proposed. Results of calculation diffraction resolution and focal depth of refractive neutron lens are discussed.

  15. Neutron Capture Nucleosynthesis

    Kiss, Miklos

    2016-01-01

    Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also investigated what neutron density is required to reproduce the measured abundance of nuclei assuming equilibrium processes. We found both of these that the medium neutron density has a particularly important role at neutron capture nucleosynthesis. About these resu...

  16. Neutron scattering. Lectures

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, neutron properties and elastic scattering, correlation functions measured by scattering experiments, symmetry of crystals, applications of neutron scattering, polarized-neutron scattering and polarization analysis, structural analysis, magnetic and lattice excitation studied by inelastic neutron scattering, macromolecules and self-assembly, dynamics of macromolecules, correlated electrons in complex transition-metal oxides, surfaces, interfaces, and thin films investigated by neutron reflectometry, nanomagnetism. (HSI)

  17. The reference neutron field - a standard neutron source for neutron measurements at the research reactor IRT-2000 in Sofia

    A reference neutron field (RFN) is used as a standard neutron source (SNS) that is influenced by the changes in the reactor core due to recharging or other causes. A whole range of measurements is carried out in a full scope, to specify its characteristics precisely. The SNS comprises: 1) the RNF certificated to the neutron energy spectrum, its location in the reactor field, being a reference measure of the differential energy distribution in the neutron flux; 2) exposure monitoring tools (detectors revealing the certified physical characteristics); 3) functional measurement apparatus (revealing the spectral characteristics). The following basic metrological characteristics are given: differential neutron energy spectrum, described by F(E) [1/cm2.s.MeV], normalized by 1 in the range 3-19 MeV and the measurement error; the conventional neutron flux density and its error. The methodology of measuring the neutron flux integral density comprises the following six steps: 1) assessment of the influence of the changes in the core configuration on the stability of the RNF (estimated in six energy ranges); 2) demonstration of RNF application in reactor physics studies; 3) irradiation of two sets of activation detectors (Au, Sc and Au, Sc, S in Al and Cd shields); 4) measurement of the detector activities by calibrated gamma- and beta- spectrometric apparatus; 5) determination of the neutron field characteristics at a certain point of the RNF by the method of activating ratios; 6) the result accuracy assessment and probabilistic error limits determination with 95% upper bound frequency. The RNF neutron energy range have been measured 6 times for a period of two years. 6 refs., 8 figs. (M.A.)

  18. Neutron Therapy Facility

    Federal Laboratory Consortium — The Neutron Therapy Facility provides a moderate intensity, broad energy spectrum neutron beam that can be used for short term irradiations for radiobiology (cells)...

  19. Different thresholds of T cell activation regulate FIV infection of CD4+CD25+ and CD4+CD25- cells

    Cellular activation plays an important role in retroviral replication. Previously, we have shown that CD4+CD25+ T cells by the virtue of their partially activated phenotype represent ideal candidates for a productive feline immunodeficiency virus (FIV) infection. In the present study, we extended our previous observations with regard to FIV replication in CD4+CD25+ and CD4+CD25- cells under different stimulation conditions. Both CD4+CD25+ and CD4+CD25- cells remain latently infected in the absence of IL-2 or concanvalinA (ConA), respectively; harboring a replication competent provirus capable of reactivation several days post-infection. While CD4+CD25+ cells require low levels of exogenous IL-2 and virus inputs for an efficient FIV replication, CD4+CD25- T cells can only be productively infected in the presence of either high concentrations of IL-2 or high virus titers, even in the absence of mitogenic stimulation. Interestingly, while high virus input activates CD4+CD25- cells to replicate FIV, it induces apoptosis in a high percentage of CD4+CD25+ T cells. High IL-2 concentrations but not high virus inputs lead to surface upregulation of CD25 and significant cellular proliferation in CD4+CD25- cells. These results suggest that CD4+CD25+ and CD4+CD25- T cells have different activation requirements which can be modulated by both viral and cytokine stimuli to reach threshold activation levels in order to harbor a productive FIV infection. This holds implications in vivo for CD4+CD25+ and CD4+CD25- cells to serve as potential reservoirs of a productive and latent FIV infection

  20. Thermal neutron imaging through XRQA2 GAFCHROMIC films coupled with a cadmium radiator

    Sacco, D.; Bedogni, R.; Bortot, D.; Palomba, M.; Pola, A.; Introini, M. V.; Lorenzoli, M.; Gentile, A.; Strigari, L.; Pressello, C.; Soriani, A.; Gómez-Ros, J. M.

    2015-10-01

    A simple and inexpensive method to perform passive thermal neutron imaging on large areas was developed on the basis of XRQA2 GAFCHROMIC films, commonly employed for quality assurance in radiology. To enhance their thermal neutron response, the sensitive face of film was coupled with a 1 mm thick cadmium radiator, forming a sandwich. By exchanging the order of Cd filter and sensitive film with respect to the incident neutron beam direction, two different configurations (beam-Cd-film and beam-film-Cd) were identified. These configurations were tested at thermal neutrons fluence values in the range 109-1010 cm-2, using the ex-core radial thermal neutron column of the ENEA Casaccia - TRIGA reactor. The results are presented in this work.

  1. Thermal neutron imaging through XRQA2 GAFCHROMIC films coupled with a cadmium radiator

    Sacco, D. [INFN – LNF, Via E. Fermi n.40, Frascati, 00044 Roma (Italy); INAIL – DIT, Via di Fontana Candida n.1, 00040 Monteporzio Catone (Italy); Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [INFN – LNF, Via E. Fermi n.40, Frascati, 00044 Roma (Italy); Bortot, D. [Politecnico di Milano, Dipartimento di Energia, Via La Masa 34, 20156 Milano (Italy); INFN – Milano, Via Celoria16, 20133 Milano (Italy); Palomba, M. [ENEA Casaccia, Via Anguillarese, 301, S. Maria di Galeria, 00123 Roma (Italy); Pola, A. [Politecnico di Milano, Dipartimento di Energia, Via La Masa 34, 20156 Milano (Italy); INFN – Milano, Via Celoria16, 20133 Milano (Italy); Introini, M.V.; Lorenzoli, M. [Politecnico di Milano, Dipartimento di Energia, Via La Masa 34, 20156 Milano (Italy); Gentile, A. [INFN – LNF, Via E. Fermi n.40, Frascati, 00044 Roma (Italy); Strigari, L. [Laboratory of Medical Physics, Regina Elena National Cancer Institute, Via E. Chianesi 53, 00144 Roma (Italy); Pressello, C. [Department of Medical Physics, Azienda Ospedaliera San Camillo Forlanini, Circonvallazione Gianicolense 87, 00152 Roma (Italy); Soriani, A. [Laboratory of Medical Physics, Regina Elena National Cancer Institute, Via E. Chianesi 53, 00144 Roma (Italy); Gómez-Ros, J.M. [INFN – LNF, Via E. Fermi n.40, Frascati, 00044 Roma (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain)

    2015-10-21

    A simple and inexpensive method to perform passive thermal neutron imaging on large areas was developed on the basis of XRQA2 GAFCHROMIC films, commonly employed for quality assurance in radiology. To enhance their thermal neutron response, the sensitive face of film was coupled with a 1 mm thick cadmium radiator, forming a sandwich. By exchanging the order of Cd filter and sensitive film with respect to the incident neutron beam direction, two different configurations (beam-Cd-film and beam-film-Cd) were identified. These configurations were tested at thermal neutrons fluence values in the range 10{sup 9}–10{sup 10} cm{sup −2}, using the ex-core radial thermal neutron column of the ENEA Casaccia – TRIGA reactor. The results are presented in this work.

  2. Neutronic fields produced by a lineal accelerator for radiotherapy

    Measurements and Monte Carlo calculations has been utilized to determine the dosimetric features as well as the neutron spectra of photoneutrons produced around an 18 MV linear accelerator for radiotherapy. Measurements were carried out with bare and Cd covered thermoluminescent dosimeters, TLD600 and TLD700, as well as inside a paraffine moderator. TLD pairs were also utilized as thermal neutrons inside a Bonner sphere spectrometer (au)

  3. Photocatalytic Hydrogen Generation by CdSe/CdS Nanoparticles.

    Qiu, Fen; Han, Zhiji; Peterson, Jeffrey J; Odoi, Michael Y; Sowers, Kelly L; Krauss, Todd D

    2016-09-14

    The photocatalytic hydrogen (H2) production activity of various CdSe semiconductor nanoparticles was compared including CdSe and CdSe/CdS quantum dots (QDs), CdSe quantum rods (QRs), and CdSe/CdS dot-in-rods (DIRs). With equivalent photons absorbed, the H2 generation activity orders as CdSe QDs ≫ CdSe QRs > CdSe/CdS QDs > CdSe/CdS DIRs, which is surprisingly the opposite of the electron-hole separation efficiency. Calculations of photoexcited surface charge densities are positively correlated with the H2 production rate and suggest the size of the nanoparticle plays a critical role in determining the relative efficiency of H2 production. PMID:27478995

  4. Soluble CD163

    Møller, Holger J

    2012-01-01

    macrophage activation syndrome, sepsis, and liver disease. Moreover, sCD163 is a general risk marker of comorbidity and mortality in several chronic inflammatory disease states. Recently, sCD163 has been shown to be strongly associated with later development of type 2 diabetes in both lean and obese subjects......, likely due to macrophage infiltration of adipose tissue and the liver. This review summarizes the current knowledge on the regulation of sCD163 in normal and pathological states and also deals with analytical aspects of sCD163 measurements in biological samples....

  5. Neutron excitation function guide for reactor dosimetry

    Neutron Excitation Function Guide for Reactor Dosimetry (NEFGRD) has been prepared in the Ukrainian Nuclear Data Center (UKRNDC) using ZVV 9.2 code for graphical data presentation. The data can be retrieved through Web or obtained on CD-ROM or as hard copy report. NEFGRD contains graphical and text information for 56 nuclides (81 dosimetry reactions). Each reaction is provided by the information part and several graphical function blocks (from one to nine). (author)

  6. Canine CD4(+)CD8(+) double-positive T cells can develop from CD4(+) and CD8(+) T cells.

    Bismarck, Doris; Moore, Peter F; Alber, Gottfried; von Buttlar, Heiner

    2014-12-15

    For a long time the expression of the CD4 and CD8 receptor on peripheral blood T cells was thought to be mutually exclusive. However, in canine peripheral blood, similar to other species as swine or human for example, mature CD4(+)CD8(+) double-positive (dp) T cells exist which simultaneously express both surface receptors and have features of activated T cells. Canine CD4(+)CD8(+)dp T cells are heterogeneous and can be divided into three subpopulations by their intensity of CD4 and CD8α expression: CD4(bright)CD8α(bright), CD4(dim)CD8α(bright) and CD4(dim)CD8α(dim). The number of CD4(+)CD8α(+)dp T cells increases after in vitro stimulation of canine peripheral blood mononuclear cells (PBMC) raising the question of their progenitor(s). Thus, the aim of our study was to characterize the progenitor(s) of canine CD4(+)CD8α(+)dp T cells. By cell tracing experiments we identified both CD4(+) single-positive (sp) and also CD8α(+)sp T cells as progenitors of canine CD4(+)CD8α(+)dp T cells after in vitro stimulation. CD4(+)sp T cells almost exclusively upregulate a CD8αα homodimer, whereas CD8α(+)sp T cells can become CD4(+)CD8αβ(+) or CD4(+)CD8αα(+). Even in the absence of other cells, highly purified CD4(+)sp T cells can become double-positive upon in vitro stimulation, whereas highly purified CD8α(+)sp T cells fail to do so. However, CD8α(+)sp T cells can additionally express CD4 when stimulated in the presence of CD4(-)CD8α(-) double-negative (dn) cells or more efficiently when stimulated in the presence of CD4(+)sp T cells. Soluble factors secreted by CD4(+)sp T cells are sufficient for the upregulation of CD4 on CD8α(+)sp T cells, but direct cell-cell contact between CD4(+)sp and CD8α(+)sp T cells is more efficient. mRNA analysis shows that additional CD4 expression on CD8α(+)sp T cells results from de novo synthesis. Thus, uptake of soluble CD4 or trogocytosis is less likely as mechanism for generation of canine double-positive T cells. CD4(+)CD

  7. Experimental research on reflected neutrons from cement material

    Neutrons reflected by the cement material were studied by nuclear fission and activation methods with a D-T neutron source. With the small enriched uranium and depleted uranium fission ionization chambers combining to the capturing detector, the 235U (wrapped by Cd foil) and 238U fission reaction rates induced by reflected neutrons are measured on the horizontal equator of the Fe shell's outer surface. The standard experimental uncertainties of fission reaction rates were 6.1%-7.3% for 235U(wrapped by Cd foil) and 6.4%-7.4% for 238U. With five kinds of activation foils of different threshold energy, the 56Fe, 27Al, 93Nb, 19F and 63Cu reaction rates induced by reflected neutrons were measured. The standard experimental uncertainties of activation reaction rates were 7.2%-8.0%. The 235U(wrapped by Cd foil) fission reaction rates with a 252Cf neutron source were compared to the ones with a D-T neutron source. The experimental results were discussed and analyzed. (authors)

  8. Measurement of Secondary Neutron Emission Double-Differential Cross Section for Deuteron Induced by 8.22 MeV Neutrons

    LIN; Meng-na; RUAN; Xi-chao; HUANG; Han-xiong; REN; Jie; LI; Yong-ming; LI; Xia; NIE; Yang-bo; ZHANG; Qi-wei; HE; Guo-zhu; ZHOU; Zu-ying

    2012-01-01

    <正>This experiment is performed to measure the time-of-flight spectra of secondary neutrons for deuteron induced by 8.22 MeV neutrons in the range of 15o-155o for CD2 and C samples, and 15o -65o for a polyethylene sample, by using the multi-detector fast neutron TOF spectrometer at the China institute of Atomic Energy (CIAE). The D(d, n)3He reaction source was used. The influence of the C in the CD2

  9. Neutron source for Neutron Capture Synovectomy

    Monte Carlo calculations were performed to obtain a thermal neutron field from a 239PuBe neutron source inside a cylindrical heterogeneous moderators for Neutron Capture Synovectomy. Studied moderators were light water and heavy water, graphite and heavy water, lucite and polyethylene and heavy water. The neutron spectrum of polyethylene and heavy water moderator was used to determine neutron spectra inside a knee model. In this model the elemental composition of synovium and synovial liquid was assumed like blood. Kerma factors for synovium and synovial liquid were calculated to compare with water Kerma factors, in this calculations the synovium was loaded with two different concentrations of Boron

  10. Neutron standard data

    The neutron standards are reviewed with emphasis on the evaluation for ENDFB-VI. Also discussed are the neutron spectrum of 252Cf spontaneous fission, activation cross sections for neutron flux measurement, and standards for neutron energies greater than 20 MeV. Recommendations are made for future work. 21 refs., 6 figs., 3 tabs

  11. Neutron dosimetry - A review

    This review summarizes information on the following subjects: (1) physical processes of importance in neutron dosimetry; (2) biological effects of neutrons; (3) neutron sources; and (4) instruments and methods used in neutron dosimetry. Also, possible improvements in dosimetry instrumentation are outlined and discussed. (author)

  12. Borner Ball Neutron Detector

    2002-01-01

    The Bonner Ball Neutron Detector measures neutron radiation. Neutrons are uncharged atomic particles that have the ability to penetrate living tissues, harming human beings in space. The Bonner Ball Neutron Detector is one of three radiation experiments during Expedition Two. The others are the Phantom Torso and Dosimetric Mapping.

  13. Superfluid neutron stars

    Langlois, David

    2001-01-01

    Neutron stars are believed to contain (neutron and proton) superfluids. I will give a summary of a macroscopic description of the interior of neutron stars, in a formulation which is general relativistic. I will also present recent results on the oscillations of neutron stars, with superfluidity explicitly taken into account, which leads in particular to the existence of a new class of modes.

  14. Neutron scattering. Lectures

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  15. Neutrostriction in Neutron stars

    Ignatovich, V. K.

    2003-01-01

    It is demonstrated that not only gravity, but also neutrostriction forces due to optical potential created by coherent elastic neutron-neutron scattering can hold a neutron star together. The latter forces can be stronger than gravitational ones. The effect of these forces on mass, radius and structure of the neutron star is estimated.

  16. Neutron scattering. Lectures

    The following topics are dealt with: Neutron sources, symmetry of crystals, diffraction, nanostructures investigated by small-angle neutron scattering, the structure of macromolecules, spin dependent and magnetic scattering, structural analysis, neutron reflectometry, magnetic nanostructures, inelastic scattering, strongly correlated electrons, dynamics of macromolecules, applications of neutron scattering. (HSI)

  17. Possibilities of Controlling Nutritious Wheat Flour by the Method of Neutron Activation Analysis

    Possibilities of controlling nutritious wheat flour by the method of neutron activation analysis are studied. It is established, that detection of contents of As, Cd, Hg, Cu and Zn in wheat flour is possible using this method and a neutron multiplier. The results of measurements were worked out by polycomparative method. (author)

  18. Neutron Capture Nucleosynthesis

    Kiss, Miklos

    2016-01-01

    Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also investigated what neutron density is required to reproduce the measured abundance of nuclei assuming equilibrium processes. We found both of these that the medium neutron density has a particularly important role at neutron capture nucleosynthesis. About these results most of the nuclei can formed at medium neutron capture density environment e.g. in some kind of AGB stars. Besides these observations our model is capable to use educational purpose.

  19. Neutron halo state of 13C

    2001-01-01

    Angular distributions for the 12C(d, p)13C transfer reactionshave been measured at Ed = 11.8 MeV, and compared with those of the DWBA calculations. By means of this comparison, density distributions of the last neutron in the ground state and the first 1/2+ state of 13C are extracted. The properties of these states in 13C have also been studied in the framework of the nonlinear relativistic mean-field theory with NL-SH parameters. It is found that the first 1/2+ state in 13C is a neutron halo state shown by both the experimental and theoretical density distributions of the last neutron.

  20. Effectiveness of custom neutron shielding in the maze of radiotherapy accelerators

    An investigation was performed to examine the neutron dose equivalent in a radiotherapy maze lined with a customised neutron shielding material. The accelerator investigated was a Varian Clinac 2100C/D using 18 MV photons, and the neutron shielding utilised at this centre was PremadexTM commercially available neutron shielding. Based on Monte Carlo simulations, properly installed customised neutron shielding may reduce the neutron dose equivalent by up to a factor of 8 outside the maze, depending upon the installation. In addition, it was determined that the neutron dose near the entrance to the maze may be reduced by approximately 40% by using customised neutron shielding in the maze, as compared with a facility not using this shielding. This would have a positive dose-saving effect in doorless maze designs. (author)

  1. Neutrons in cancer therapy

    Allen, Barry J.

    1995-03-01

    The role of neutrons in the management of cancer has a long history. However, it is only in recent years that neutrons are beginning to find an accepted place as an efficacious radiation modality. Fast neutron therapy is already well established for the treatment of certain cancers, and clinical trials are ongoing. Californium neutron sources are being used in brachytherapy. Boron neutron capture therapy has been well tested with thermal neutrons and epithermal neutron dose escalation studies are about to commence in the USA and Europe. Possibilities of neutron induced auger electron therapy are also discussed. With respect to chemotherapy, prompt neutron capture analysis is being used to study the dose optimization of chemotherapy in the management of breast cancer. The rationales behind these applications of neutrons in the management of cancer are examined.

  2. High energy neutron detector

    Wiegand, C.

    1948-04-27

    It is the purpose of this paper to describe a neutron detector suitable for monitoring a flux of neutrons whose energy is greater than about 50 MeV. Detection of the neutrons is accomplished by their ability to induce fission in heavy elements. Kelly and Wiegand studied the neutron fission of Bi, Pb, Ti, Hg, Au, and Pt at various neutron energies and the presently described counter is an application of this work.

  3. Imaging with Scattered Neutrons

    Ballhausen, H; Gähler, R; Trapp, M; Van Overberghe, A

    2006-01-01

    We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-resolution images by scattered neutron radiography and tomography are presented.

  4. Delayed-neutron activities produced in fission: Mass range 122--146

    Delayed-neutron emission from mass separated heavy fission products has been studied using a sensitive neutron counter. Twelve new delayed-neutron precursors have been found, namely 122Ag, 123Ag, 127In, 128Cd (or 128In/sub m/), 128In, 129In (two isomers), 130In, 131In, 132In, 133Sn, and 136Sb. The half-life determination for 11 other precursors has been improved

  5. Measurement of epithermal neutrons by a coherent demodulation technique

    Horiuchi, N; Takahashi, H; Kobayashi, H; Harasawa, S

    2000-01-01

    Epithermal neutrons have been measured using a neutron dosimeter via a coherent demodulation technique. This dosimeter consists of CsI(Tl)-photodiode scintillation detectors, four of which are coupled to neutron-gamma converting foils of various sizes. Neutron-gamma converting foils of In, Au and Co materials were used, each of which has a large capture cross section which peaks in the epithermal neutron energy region. The type of foil was selected according to the material properties that best correspond to the energy of the epithermal neutrons to be measured. In addition, the proposed technique was applied using Au-foils in order to measure the Cd ratio. The validity of the proposed technique was examined using an sup 2 sup 4 sup 1 Am-Be source placed in a testing stack of polyethylene blocks, and the results were compared with the theoretical values calculated by the Monte Carlo calculation. Finally, the dosimeter was applied for measuring epithermal neutrons and the Cd ratio in an experimental beam-tube o...

  6. Position sensitive detection of neutrons in high radiation background field

    We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e− radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm2) spectroscopic Timepix detector adapted for neutron detection utilizing very thin 10B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10−4

  7. Spectral fluence of neutrons generated by radiotherapeutic Linacs

    Spectral fluences of neutrons generated in the heads of the radiotherapeutic linacs Varian Clinac 2100 C/D and Siemens ARTISTE were measured by means of the Bonner spheres spectrometer whose active detector of thermal neutrons was replaced by an activation detector, i.e. a tablet made of pure manganese. Measurements with different collimator settings reveal an interesting dependence of neutron fluence on the area defined by the collimator jaws. The determined neutron spectral fluences were used to derive ambient dose equivalent rate along the treatment coach. To clarify at which components of the linac neutrons are mainly created, the measurements were complemented with MCNPX calculations based on a realistic model of the Varian Clinac. (authors)

  8. The instrumental neutron activation determination of impurities in technical cobalt

    Instrumental neutron activation techniques for determination of 13 impurities with detection limit 10-5 - 10-2% in technical cobalt have been developed by using thermal and epithermal neutrons of nuclear reactor. Self-shielding and disturbance of neutron flux(Co59 has high capture cross-section of neutrons) by sample were taken into account by using some references and from the results obtained in preliminary experiments. Samples and standards have been placed in such a way that neutron flux disturbance was less than 2-3%. The Al-Pb-Cd-Cu filter was used for absorption of low energy γ-rays of Co60m and Co61. (author)

  9. Neutron total cross section measurements with the {sup 6}Li-ZnS(Ag) scintillator (BC702) employing a neutron and noise separation technique

    Shin, Sung Gyun; Kye, Yong Uk; Cho, Moo Hyun [Pohang University of Science and Technology, Pohang (Korea, Republic of); Namkung, Won [Pohang Accelerator Laboratory, Pohang (Korea, Republic of); Kim, Gui Nyun [Kyungpook National University, Daegu (Korea, Republic of); Lee, Man Woo; Kang, Yeong Rok [Dongnam Institute of Radiological and Medical Science, Busan (Korea, Republic of)

    2014-05-15

    The neutron total cross-section of natural Dy has been measured in the energy region from 0.01 to 100 eV by using the neutron time-of-flight method at Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled Ta target with a water moderator, and a timeof-flight path with an 11-m length. A {sup 6}Li-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.5 cm has been used as a neutron detector, and a metallic Dy plate has been used for the neutron transmission measurement. The background level has been determined by using notch filters of Co, Ta, and Cd sheets. In order to reduce the gamma rays from Bremsstrahlung and from neutron capture, we have employed a neutron-gamma separation system based on their different pulse shapes.

  10. Pulsed neutron sources for epithermal neutrons

    It is shown how accelerator based neutron sources, giving a fast neutron pulse of short duration compared to the neutron moderation time, promise to open up a new field of epithermal neutron scattering. The three principal methods of fast neutron production: electrons, protons and fission boosters will be compared. Pulsed reactors are less suitable for epithermal neutrons and will only be briefly mentioned. The design principle of the target producing fast neutrons, the moderator and reflector to slow them down to epithermal energies, and the cell with its beam tubes and shielding will all be described with examples taken from the new Harwell electron linac to be commissioned in 1978. A general comparison of pulsed neutron performance with reactors is fraught with difficulties but has been attempted. Calculation of the new pulsed source fluxes and pulse widths is now being performed but we have taken the practical course of basing all comparisons on extrapolations from measurements on the old 1958 Harwell electron linac. Comparisons for time-of-flight and crystal monochromator experiments show reactors to be at their best at long wavelengths, at coarse resolution, and for experiments needing a specific incident wavelength. Even existing pulsed sources are shown to compete with the high flux reactors in experiments where the hot neutron flux and the time-of-flight methods can be best exploited. The sources under construction can open a new field of inelastic neutron scattering based on energy transfer up to an electron volt and beyond

  11. Neutron Scintillators for Downscattered Neutron Imaging

    Images of neutron emission from Inertial Confinement Fusion (ICF) (D,T) targets reveal the internal structure of the target during the fusion burn. 14-MeV neutrons provide images which show the size and shape of the region where (D,T) fusion is most intense. Images based on ''downscattered'' neutrons with energies from 5 to 10 MeV emphasize the distribution of deuterium and tritium fuel within the compressed target. The downscattered images are difficult to record because the lower energy neutrons are detected with less efficiency than the much more intense pulse of 14-MeV neutrons which precedes them at the detector. The success of downscattered neutron imaging will depend on the scintillation decay times and the sensitivities to lower-energy neutrons of the scintillator materials that are used in the detectors. A time-correlated photon counting system measured the decay of neutron-induced scintillation for times as long as several hundred ns. Accelerators at the University of California, Berkeley, and the Lawrence Livermore National Laboratory provided stable 14-MeV neutron sources for the measurements. Measurements of scintillator decay characteristics indicate that some commercially available scintillators should be suitable for recording both 14-MeV and downscattered neutron images of compressed ICF targets

  12. Weapons Neutron Research Facility (WNR)

    Federal Laboratory Consortium — The Weapons Neutron Research Facility (WNR) provides neutron and proton beams for basic, applied, and defense-related research. Neutron beams with energies ranging...

  13. CD3+CD8+CD161high Tc17 cells are depleted in HIV-infection

    Gaardbo, Julie Christine; Hartling, Hans Jakob; Thorsteinsson, Kristina;

    2012-01-01

    CD8+ Tc17 cells with pro-inflammatory properties have only recently been acknowledged, and Tc17 cells in HIV-infection are undescribed. CD3+CD8+CD161 Tc17 cells and the production of Interleukin-17 were examined in untreated and treated HIV-infected patients, HIV-HCV co-infected patients and...... healthy controls. Depletion of CD3+CD8+CD161 Tc17 cells and diminished production of Interleukin-17 in HIV-infected patients was found. The level of Tc17 cells was associated with the level of the CD4+ count in treated patients....

  14. CD3+CD8+CD161high Tc17 cells are depleted in HIV-infection.

    Gaardbo, Julie Christine; Hartling, Hans Jakob; Thorsteinsson, Kristina; Ullum, Henrik; Nielsen, Susanne Dam

    2013-02-20

    CD8 Tc17 cells with pro-inflammatory properties have only recently been acknowledged, and Tc17 cells in HIV-infection are not described. CD3CD8CD161 Tc17 cells and the production of interleukin (IL)-17 were examined in untreated and treated HIV-infected patients, HIV-hepatitis C virus co-infected patients, and healthy controls. Depletion of CD3CD8CD161 Tc17 cells and diminished production of IL-17 in HIV-infected patients were found. The level of Tc17 cells was associated with the CD4 cell count in treated patients. PMID:23135168

  15. Broadband Neutron Interferometer

    Pushin, Dmitry A; Hussey, Dan; Miao, Houxun; Arif, Muhammad; Cory, David G; Huber, Michael G; Jacobson, David; LaManna, Jacob; Parker, Joseph D; Shinohara, Taken; Ueno, Wakana; Wen, Han

    2016-01-01

    We demonstrate a two phase-grating, multi-beam neutron interferometer by using a modified Ronchi setup in a far-field regime. The functionality of the interferometer is based on the universal \\moire effect that was recently implemented for X-ray phase-contrast imaging in the far-field regime. Interference fringes were achieved with monochromatic, bichromatic, and polychromatic neutron beams; for both continuous and pulsed beams. This far-field neutron interferometry allows for the utilization of the full neutron flux for precise measurements of potential gradients, and expands neutron phase-contrast imaging techniques to more intense polycromatic neutron beams.

  16. Reactor neutron dosimetry

    An analysis of requirements and possibilities for experimental neutron spectrum determination during the reactor pressure vessel surveil lance programme is given. Fast neutron spectrum and neutron dose rate were measured in the Fast neutron irradiation facility of our TRIGA reactor. It was shown that the facility can be used for calibration of neutron dosimeters and for irradiation of samples sensitive to neutron radiation. The investigation of the unfolding algorithm ITER was continued. Based on this investigations are two specialized unfolding program packages ITERAD and ITERGS written this year. They are able to unfold data from activation detectors and NaI(T1) gamma spectrometer respectively

  17. Neutron in biology

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    Neutron in biology can provide an experimental method of directly locating relationship of proteins and DNA. However, there are relatively few experimental study of such objects since it takes a lot of time to collect a sufficient number of Bragg reflections and inelastic spectra due to the low flux of neutron illuminating the sample. Since a next generation neutron source of JAERI will be 5MW spallation neutron source and its effective neutron flux will be 10{sup 2} to 10{sup 3} times higher than the one of JRR-3M, neutron in biology will open a completely new world for structural biology. (author)

  18. Layered semiconductor neutron detectors

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  19. Pulsed neutron porosity logging

    A borehole logging tool employing a pulsed neutron source and a pair of spaced-apart epithermal neutron detectors is lowered into a borehole traversing a subsurface formation. The formation is irradiated with bursts of fast neutrons and the epithermal neutrons returning to the borehole as a result of such irradiation are detected by the pair of epithermal neutrons detectors. These detected epithermal neutrons are both time resolved and time integrated during their epithermal dieaway spectrum to provide indications of lithology independent porosity and lithology dependent porosity respectively. 6 refs

  20. Neutron-antineutron oscillation in neutron stars

    It is investigated if the neutron-antineutron oscillation might affect the stability of a neutron star. Because of the very high density inside a neutron star the possibility is reduced drastically and it is shown that only a small percentage of the neutrons are capable of becoming antineutrons and thus are annihilated. Fixing the lower limit (referred to the vacuum) of τn,antin as 106 s, it is obtained that only 1021 erg/s are produced by this mechanism, so the thermodynamical equilibrium of the star is unaffected

  1. Neutron scattering and spallation neutron sources

    Neutron scattering as a probe of microscopic structure and dynamics is a powerful tool for research in a wide variety of fields, and an accelerator-based spallation neutron source can supply high flux pulses for neutron scattering. The characteristics of neutron scattering, the principle and development of spallation neutron sources, and their advantages in multidisciplinary applications are summarized. In the proposed project of the Chinese Spallation Neutron Source the target station will consist of a piece-stacked tungsten target, a Be/Fe reflector and an Fe/heavy concrete bio-protected shelter. The pulsed neutron flux will be up to 2.4 x 1016 n/cm2/s under a nuclear power of 100 kW. Five neutron scattering instruments--a high flux powder diffractometer, a high resolution powder diffractometer, small angle diffractometer, multi-functional reflectometer and direct geometry inelastic spectrometer, will be constructed as the first step to cover most neutron scattering applications. (authors)

  2. Naiskoori uus CD

    2007-01-01

    Tallinna Tehnikaülikooli Akadeemilise Naiskoori uue CD "...nagu puhas mõte" esitluskontserdist 21. veebr. Tallinna Matkamajas. TTÜ Akadeemilise Naiskoori 55. aastapäeva kontserdist 23. mail TTÜ aulas

  3. Advances in imaging with thermal neutrons

    Experiments have been conducted using a modern high-resolution 3He two-dimensional position-sensitive detection chamber combined with coded apertures to produce images by means of thermal neutrons. These images are comparable to those produced by gamma ray imaging, but with some important differences. The detector is much less sensitive to the fast neutrons than to the thermalized component. Therefore, assuming that the neutron source has a fission spectrum, the brightest regions in an image represent moderating material in close proximity to the source, rather than the source itself. Earlier experiments have shown that useful contrast can be produced with thermal neutrons using thin masks made of metallic Cd sheet, but the resolution in those experiments was detector-limited at a few centimeters per pixel. The newer detector can resolve a line image with a fwhm resolution of about 1 mm. The technique could in principle be used in re-entry vehicle on-site inspections to count multiple nuclear warheads. Thermal neutrons carry no detailed spectral information, so their detection should not be as intrusive as gamma ray imaging. This technique can be used in nuclear materials management and arms control

  4. Neutron anatomy

    Bacon, G.E. [Univ. of Sheffield (United Kingdom)

    1994-12-31

    The familiar extremes of crystalline material are single-crystals and random powders. In between these two extremes are polycrystalline aggregates, not randomly arranged but possessing some preferred orientation and this is the form taken by constructional materials, be they steel girders or the bones of a human or animal skeleton. The details of the preferred orientation determine the ability of the material to withstand stress in any direction. In the case of bone the crucial factor is the orientation of the c-axes of the mineral content - the crystals of the hexagonal hydroxyapatite - and this can readily be determined by neutron diffraction. In particular it can be measured over the volume of a piece of bone, utilizing distances ranging from 1mm to 10mm. The major practical problem is to avoid the intense incoherent scattering from the hydrogen in the accompanying collagen; this can best be achieved by heat-treatment and it is demonstrated that this does not affect the underlying apatite. These studies of bone give leading anatomical information on the life and activities of humans and animals - including, for example, the life history of the human femur, the locomotion of sheep, the fracture of the legs of racehorses and the life-styles of Neolithic tribes. We conclude that the material is placed economically in the bone to withstand the expected stresses of life and the environment. The experimental results are presented in terms of the magnitude of the 0002 apatite reflection. It so happens that for a random powder the 0002, 1121 reflections, which are neighboring lines in the powder pattern, are approximately equal in intensity. The latter reflection, being of manifold multiplicity, is scarcely affected by preferred orientation so that the numerical value of the 0002/1121 ratio serves quite accurately as a quantitative measure of the degree of orientation of the c-axes in any chosen direction for a sample of bone.

  5. Neutron anatomy

    The familiar extremes of crystalline material are single-crystals and random powders. In between these two extremes are polycrystalline aggregates, not randomly arranged but possessing some preferred orientation and this is the form taken by constructional materials, be they steel girders or the bones of a human or animal skeleton. The details of the preferred orientation determine the ability of the material to withstand stress in any direction. In the case of bone the crucial factor is the orientation of the c-axes of the mineral content - the crystals of the hexagonal hydroxyapatite - and this can readily be determined by neutron diffraction. In particular it can be measured over the volume of a piece of bone, utilizing distances ranging from 1mm to 10mm. The major practical problem is to avoid the intense incoherent scattering from the hydrogen in the accompanying collagen; this can best be achieved by heat-treatment and it is demonstrated that this does not affect the underlying apatite. These studies of bone give leading anatomical information on the life and activities of humans and animals - including, for example, the life history of the human femur, the locomotion of sheep, the fracture of the legs of racehorses and the life-styles of Neolithic tribes. We conclude that the material is placed economically in the bone to withstand the expected stresses of life and the environment. The experimental results are presented in terms of the magnitude of the 0002 apatite reflection. It so happens that for a random powder the 0002, 1121 reflections, which are neighboring lines in the powder pattern, are approximately equal in intensity. The latter reflection, being of manifold multiplicity, is scarcely affected by preferred orientation so that the numerical value of the 0002/1121 ratio serves quite accurately as a quantitative measure of the degree of orientation of the c-axes in any chosen direction for a sample of bone

  6. Sources of ultracold neutrons

    The results of comparative experimental investigations to study ultracold neutron yields from different neutron moderator-converters are presented. The installation is described which is based on a WWR-K reactor once-through beam hole. The neutron yields were measured using Al, Mg, ZrHsub(1.9), H2O and H2 neutron converters at 80 and 300 K. For H2 converters pressure dependences of the neutron yield were also measured in the 0.1-1.5 atm. pressure range. Among solid neutron converters the ZrHsub(1.9) one possesses the highest ultracold neutron yield, whereas among all the converters tested the best performance was shown by the frozen water one, the ultracold neutron count with the proportional He3 counter being about 500ssup(-1)

  7. Neutron radiation capture

    For all stable and experimentally studied radionuclides evaluated data are presented on cross sections of thermal neutrons, on resonance integrals and medium neutron cross sections with energy of 30 KeV. Refs, figs and tabs

  8. Neutron color image intensifier

    Neutron radiography is expanding from the conventional reactor based imaging to the imaging by accelerator based pulsed neutron source. Among them, an expectation for image intensifier technology is increasing especially for video rate dynamic image detection or time dependent imaging in a pulsed neutron source. Based on the X-ray color image intensifier technology, Toshiba has developed neutron color image intensifiers as a powerful imaging tool for dynamic and time dependent neutron radiographics. In this paper, the construction and the feature of the developed neutron color image intensifier and some examples of neutron images are presented. I would be grateful if this paper helps for wide application of neutron color image intensifiers. (author)

  9. INVESTIGATION OF CdTe/CdS HETEROJUNCTION CHARACTERISTICS%CdTe/CdS异质结特性

    郭江; 王万录; 刘高斌; 冯良桓

    2003-01-01

    从理论上对CdTe/CdS太阳电池CdS/CdTe异质结的特性进行了研究和讨论,结果表明可以简单利用改变CdTe、CdS两种半导体材料的掺杂浓度来改变CdS/CdTe异质结的能带结构.针对不同的能带结构采用了不同的物理模型,得到的CdS/CdTe异质结伏安特性曲线有一折点,且折点位置随异质结能带结构的变化而变化.

  10. Imaging with Scattered Neutrons

    Ballhausen, H.; Abele, H.; Gaehler, R.; Trapp, M; Van Overberghe, A.

    2006-01-01

    We describe a novel experimental technique for neutron imaging with scattered neutrons. These scattered neutrons are of interest for condensed matter physics, because they permit to reveal the local distribution of incoherent and coherent scattering within a sample. In contrast to standard attenuation based imaging, scattered neutron imaging distinguishes between the scattering cross section and the total attenuation cross section including absorption. First successful low-noise millimeter-re...

  11. Properties of neutron sources

    The Conference presentations were divided into sessions devoted to the following topics: white neutron sources, primarily pulsed (6 papers); fast neutron fields (5 papers); Californium-252 prompt fission neutron spectra (14 papers); monoenergetic sources and filtered beams (11 papers); 14 MeV neutron sources (10 papers); selected special application (one paper); and a general interest session (4 papers). Individual abstracts were prepared separately for the papers

  12. Isotopic neutron sources for neutron activation analysis

    This User's Manual is an attempt to provide for teaching and training purposes, a series of well thought out demonstrative experiments in neutron activation analysis based on the utilization of an isotopic neutron source. In some cases, these ideas can be applied to solve practical analytical problems. 19 refs, figs and tabs

  13. Response of quiescent and total tumor cells in solid tumors to neutrons with various cadmium ratios

    Purpose: Response of quiescent (Q) and total tumor cells in solid tumors to neutron irradiation with three different cadmium (Cd) ratios was examined. The role of Q cells in tumor control was also discussed. Methods and Materials: C3H/He mice bearing SCC VII tumors received continuous administration of 5-bromo-2'-deoxyuridine (BrdU) for 5 days using implanted mini-osmotic pumps to label all proliferating (P) cells. Thirty minutes after intraperitoneal injection of sodium borocaptate-10B (BSH), or 3 h after oral administration of dl-p-boronophenylalanine-10B (BPA), the tumors were irradiated with neutrons, or those without 10B-compounds were irradiated with gamma rays. This neutron irradiation was performed using neutrons with three different cadmium (Cd) ratios. The tumors were then excised, minced, and trypsinized. The tumor cell suspensions were incubated with cytochalasin-B (a cytokinesis-blocker), and the micronucleus (MN) frequency in cells without BrdU labeling (Q cells) was determined using immunofluorescence staining for BrdU. The MN frequency in total (P + Q) tumor cells was determined from tumors that were not pretreated with BrdU. The sensitivity to neutrons was evaluated in terms of the frequency of induced micronuclei in binuclear tumor cells (MN frequency). Results: Without 10B-compounds, the MN frequency in Q cells was lower than that in the total cell population. The sensitivity difference between total and Q cells was reduced by neutron irradiation. Relative biological effectiveness (RBE) of neutrons compared with gamma rays was larger in Q cells than in total cells, and the RBE values for low-Cd-ratio neutrons tended to be larger than those for high-Cd-ratio neutrons. With 10B-compounds, MN frequency for each cell population was increased, especially for total cells. This increase in MN frequency was marked when high-Cd-ratio neutrons were used. BPA increased the MN frequency for total tumor cells more than BSH. Nevertheless, the sensitivity of Q

  14. Segmented CdWO4 detector for low background experiments at DUSEL

    Mei, Dongming; Sun, Yongchen; Day, Alyssa; Thomas, Keenan; Perevozchikov, Oleg

    2010-11-01

    We propose to develop a segmented CdWO4 scintillator array for detecting geo-neutrinos, neutrinoless double-beta, and dark matter. The detection of geo-neutrinos can shed light on the sources of the terrestrial heat flow, on the present composition, and on the origins of the Earth. The development of a new technique to detect geo-neutrinos through charge current antineutrino capture processes on ^106Cd is very interesting. This target allows us to detect all of geo-neutrinos from uranium, thorium, and potassium decays. When it is built, the detector can be also used to detect neutrinoless double-beta decay with ^116Cd. Both enriched ^106Cd and ^116Cd can be used to search for dark matter from the Universe. This paper will present RD results on the energy response of gamma-rays and neutrons from three small CdWO4 detectors.

  15. Uses of reactor neutrons for studying the microcomposition of materials

    Reactor neutrons constitute excellents 'probes' for exploring and measuring a wide range both of minor and trace constituents in solids and liquids with high sensitivity because of their transparency in materials. Nondestructive neutron prompt-gamma analysis (PGA) utilizing either cold or thermal neutrons, such as at JRR-3M, is compared and contrasted to the more common (delayed) instrumental neutron activation analysis (INAA) and epithermal NAA. Clearly PGA offers high sensitivity for selected elements: B, H, Cd and REE's in suitable matrices, and is therefore, complementary to INAA which is not as useful for them, or for Ni, Sn, Fe, C or N. Recent INAA applications in our laboratory that demonstrate some of the uniqueness of neutron methods include use of epithermal neutrons for small biological specimens to measure Cd, K, As, Zn and, multielemental INAA for environmental pollution studies. The latter involves large data sets of multielemental concentrations which are subjected to statistical multivariant factor analysis to reveal unknown or unsuspected quantitative relationships among groups of trace constituents. These patterns, or 'factors' are shown to be uniquely related to pollution sources and can be utilized to compute the relative source contributions at a given receptor site. (author)

  16. Experimental studies on neutron attenuation with polyethylene slabs in the south beam end of KAMINI reactor

    The neutron attenuating properties of polyethylene slabs are studied in this experiment. Better thermal neutron attenuation is observed in high density slabs compared to low density slabs. In the fast neutron attenuation similar behaviour is seen between both high and low density slabs. The attenuation factors are found over a thickness of 18-30 cm for the measured reaction rates of 55Mn (n,γ) 56Mn, 63Cu (n,γ) 64Cu, 23Na (n,γ) 24Na, 197Au (n,γ)198Au, 180Hf (n,n') 180mHf, 195Pt (n,n') 195mPt, 111Cd(n, n') 111mCd; 115In(n,n') In115m and 56Fe (n,p) 56Mn reactions representative of thermal, epithermal and fast neutron fluxes. A comparative analysis with the neutron attenuation behaviour in water is also made. (author)

  17. Thin film cadmium telluride charged particle sensors for large area neutron detectors

    Murphy, J. W.; Smith, L.; Calkins, J.; Mejia, I.; Cantley, K. D.; Chapman, R. A.; Quevedo-Lopez, M.; Gnade, B., E-mail: gnade@utdallas.edu [Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States); Kunnen, G. R.; Allee, D. R. [Flexible Display Center, Arizona State University, Phoenix, Arizona 85284 (United States); Sastré-Hernández, J.; Contreras-Puente, G. [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Mexico City 07738 (Mexico); Mendoza-Pérez, R. [Universidad Autónoma de la Ciudad de México, Mexico City 09790 (Mexico)

    2014-09-15

    Thin film semiconductor neutron detectors are an attractive candidate to replace {sup 3}He neutron detectors, due to the possibility of low cost manufacturing and the potential for large areas. Polycrystalline CdTe is found to be an excellent material for thin film charged particle detectors—an integral component of a thin film neutron detector. The devices presented here are characterized in terms of their response to alpha and gamma radiation. Individual alpha particles are detected with an intrinsic efficiency of >80%, while the devices are largely insensitive to gamma rays, which is desirable so that the detector does not give false positive counts from gamma rays. The capacitance-voltage behavior of the devices is studied and correlated to the response due to alpha radiation. When coupled with a boron-based neutron converting material, the CdTe detectors are capable of detecting thermal neutrons.

  18. Neutrons in medicine

    The potential advantages for the treatment of solid human tumours with high LET radiation are outlined. Two different kinds of neutron radio-therapy a) boron capture therapy with slow neutrons and b) fast neutron radiotherapy are briefly reviewed together with some clinical results for the latter. Radiotherapy with charged nuclear particles is also mentioned. (UK)

  19. Fundamental neutron physics

    Fundamental physics experiments of merit can be conducted at the proposed intense neutron sources. Areas of interest include: neutron particle properties, neutron wave properties, and fundamental physics utilizing reactor produced γ-rays. Such experiments require intense, full-time utilization of a beam station for periods ranging from several months to a year or more

  20. Neutron radiography with cyclotron

    The technique using thermal neutrons was demanded because of its inspection ability to show hydrogeneous material such as plastics, water, explosives or composite materials and irradiated nuclear fuel capsules. This paper describes some experimental results and applications in neutron radiography by the use of several small cyclotrons producing neutrons by Be(p,n) reaction. (author)

  1. Thermal neutron beamline monitor

    A detector has been developed which has characteristics that make it suitable for use as a neutron beamline monitor on the Spallation Neutron Source. Efficiency has been reduced to 10-4, pulse pair resolution is 50 nSecs and it presents minimal obstruction to the neutron beam. (author)

  2. International Neutron Radiography Newsletter

    Domanus, Joseph Czeslaw

    1986-01-01

    At the First World Conference on Neutron Radiography i t was decided to continue the "Neutron Radiography Newsletter", published previously by J.P. Barton, as the "International Neutron Radiography Newsletter" (INRNL), with J.C. Doraanus as editor. The British Journal of Non-Destructive Testing...

  3. Polarized Neutron Scattering

    Roessli, B.; Böni, P.

    2000-01-01

    The technique of polarized neutron scattering is reviewed with emphasis on applications. Many examples of the usefulness of the method in various fields of physics are given like the determination of spin density maps, measurement of complex magnetic structures with spherical neutron polarimetry, inelastic neutron scattering and separation of coherent and incoherent scattering with help of the generalized XYZ method.

  4. Neutron absorbers and detector types for spent fuel verification using the self-interrogation neutron resonance densitometry

    Rossa, Riccardo, E-mail: rrossa@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Borella, Alessandro, E-mail: aborella@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium); Labeau, Pierre-Etienne, E-mail: pelabeau@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Pauly, Nicolas, E-mail: nipauly@ulb.ac.be [Université libre de Bruxelles, Ecole polytechnique de Bruxelles, Service de Métrologie Nucléaire (CP 165/84), Avenue F.D. Roosevelt, 50, B1050 Brussels (Belgium); Meer, Klaas van der, E-mail: kvdmeer@sckcen.be [SCK-CEN, Belgian Nuclear Research Centre, Boeretang, 200, B2400 Mol (Belgium)

    2015-08-11

    The Self-Interrogation Neutron Resonance Densitometry (SINRD) is a passive non-destructive assay (NDA) technique that is proposed for the direct measurement of {sup 239}Pu in a spent fuel assembly. The insertion of neutron detectors wrapped with different neutron absorbing materials, or neutron filters, in the central guide tube of a PWR fuel assembly is envisaged to measure the neutron flux in the energy region close to the 0.3 eV resonance of {sup 239}Pu. In addition, the measurement of the fast neutron flux is foreseen. This paper is focused on the determination of the Gd and Cd neutron filters thickness to maximize the detection of neutrons within the resonance region. Moreover, several detector types are compared to identify the optimal condition and to assess the expected total neutron counts that can be obtained with the SINRD measurements. Results from Monte Carlo simulations showed that ranges between 0.1–0.3 mm and 0.5–1.0 mm ensure the optimal conditions for the Gd and Cd filters, respectively. Moreover, a {sup 239}Pu fission chamber is better suited to measure neutrons close to the 0.3 eV resonance and it has the highest sensitivity to {sup 239}Pu, in comparison with a {sup 235}U fission chamber, with a {sup 3}He proportional counter, and with a {sup 10}B proportional counter. The use of a thin Gd filter and a thick Cd filter is suggested for the {sup 239}Pu and {sup 235}U fission chambers to increase the total counts achieved in a measurement, while a thick Gd filter and a thin Cd filter are envisaged for the {sup 3}He and {sup 10}B proportional counters to increase the sensitivity to {sup 239}Pu. We concluded that an optimization process that takes into account measurement time, filters thickness, and detector size is needed to develop a SINRD detector that can meet the requirement for an efficient verification of spent fuel assemblies.

  5. Nuclear $\\beta^+$/EC decays in covariant density functional theory and the impact of isoscalar proton-neutron pairing

    Niu, Z M; Liu, Q; Liang, H Z; Guo, J Y

    2013-01-01

    Self-consistent proton-neutron quasiparticle random phase approximation based on the spherical nonlinear point-coupling relativistic Hartree-Bogoliubov theory is established and used to investigate the $\\beta^+$/EC-decay half-lives of neutron-deficient Ar, Ca, Ti, Fe, Ni, Zn, Cd, and Sn isotopes. The isoscalar proton-neutron pairing is found to play an important role in reducing the decay half-lives, which is consistent with the same mechanism in the $\\beta$ decays of neutron-rich nuclei. The experimental $\\beta^+$/EC-decay half-lives can be well reproduced by a universal isoscalar proton-neutron pairing strength.

  6. Downregulation of CD44 reduces doxorubicin resistance of CD44+CD24- breast cancer cells

    Phuc PV

    2011-06-01

    Full Text Available Pham Van Phuc, Phan Lu Chinh Nhan, Truong Hai Nhung, Nguyen Thanh Tam, Nguyen Minh Hoang, Vuong Gia Tue, Duong Thanh Thuy, Phan Kim NgocLaboratory of Stem Cell Research and Application, University of Science, Vietnam National University, Ho Chi Minh, VietnamBackground: Cells within breast cancer stem cell populations have been confirmed to have a CD44+CD24- phenotype. Strong expression of CD44 plays a critical role in numerous types of human cancers. CD44 is involved in cell differentiation, adhesion, and metastasis of cancer cells.Methods: In this study, we reduced CD44 expression in CD44+CD24- breast cancer stem cells and investigated their sensitivity to an antitumor drug. The CD44+CD24- breast cancer stem cells were isolated from breast tumors; CD44 expression was downregulated with siRNAs followed by treatment with different concentrations of the antitumor drug.Results: The proliferation of CD44 downregulated CD44+CD24- breast cancer stem cells was decreased after drug treatment. We noticed treated cells were more sensitive to doxorubicin, even at low doses, compared with the control groups.Conclusions: It would appear that expression of CD44 is integral among the CD44+CD24- cell population. Reducing the expression level of CD44, combined with doxorubicin treatment, yields promising results for eradicating breast cancer stem cells in vitro. This study opens a new direction in treating breast cancer through gene therapy in conjunction with chemotherapy.Keywords: antitumor drugs, breast cancer stem cells, CD44, CD44+CD24- cells, doxorubicin

  7. Neutron removal cross section as a measure of neutron skin

    D. Q. Fang; Y. G. Ma; Cai, X. Z.(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 201800, Shanghai, China); Tian, W.D.; Wang, H. W.

    2010-01-01

    We study the relation between neutron removal cross section ($\\sigma_{-N}$) and neutron skin thickness for finite neutron rich nuclei using the statistical abrasion ablation (SAA) model. Different sizes of neutron skin are obtained by adjusting the diffuseness parameter of neutrons in the Fermi distribution. It is demonstrated that there is a good linear correlation between $\\sigma_{-N}$ and the neutron skin thickness for neutron rich nuclei. Further analysis suggests that the relative increa...

  8. CD4+/CD8+ double-positive T cells

    Overgaard, Nana H; Jung, Ji-Won; Steptoe, Raymond J;

    2015-01-01

    lymphoid tissues of numerous species, as well as in numerous disease settings, including cancer. The expression of CD4 and CD8 is regulated by a very strict transcriptional program involving the transcription factors Runx3 and ThPOK. Initially thought to be mutually exclusive within CD4(+) and CD8(+) T...... reports describing cytotoxic or suppressive roles for these cells. In this review, we describe how transcriptional regulation, lineage of origin, heterogeneity of CD4 and CD8 expression, age, species, and specific disease settings influence the functionality of this rarely studied T cell population....

  9. Neutron scattering. Experiment manuals

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  10. Neutron scattering. Experiment manuals

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2010-07-01

    The following topics are dealt with: The thermal triple axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, neutron polarization analysis with tht time-of-flight spectrometer DNS, the neutron spin-echo spectrometer J-NSE, small-angle neutron scattering with the KWS-1 and KWS-2 diffractometers, the very-small-angle neutron scattering diffractrometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  11. Neutron scattering. Experiment manuals

    Brueckel, Thomas; Heger, Gernot; Richter, Dieter; Roth, Georg; Zorn, Reiner (eds.)

    2012-07-01

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, the neutron polarization analyzer DNS, the neutron spin-echo spectrometer J-NSE, the small-angle neutron diffractometers KWS-1/-2, the very-small-angle neutron diffractometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  12. Grazing Incidence Neutron Optics

    Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

    2013-01-01

    Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20.ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

  13. Neutron scatter camera

    Mascarenhas, Nicholas; Marleau, Peter; Brennan, James S.; Krenz, Kevin D.

    2010-06-22

    An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4.pi.. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

  14. Neutron techniques in Safeguards

    An essential part of Safeguards is the ability to quantitatively and nondestructively assay those materials with special neutron-interactive properties involved in nuclear industrial or military technology. Neutron techniques have furnished most of the important ways of assaying such materials, which is no surprise since the neutronic properties are what characterizes them. The techniques employed rely on a wide selection of the many methods of neutron generation, detection, and data analysis that have been developed for neutron physics and nuclear science in general

  15. Neutron scattering. Experiment manuals

    The following topics are dealt with: The thermal triple-axis spectrometer PUMA, the high-resolution powder diffractometer SPODI, the hot single-crystal diffractometer HEiDi for structure analysis with neutrons, the backscattering spectrometer SPHERES, the neutron polarization analyzer DNS, the neutron spin-echo spectrometer J-NSE, the small-angle neutron diffractometers KWS-1/-2, the very-small-angle neutron diffractometer with focusing mirror KWS-3, the resonance spin-echo spectrometer RESEDA, the reflectometer TREFF, the time-of-flight spectrometer TOFTOF. (HSI)

  16. CD4(+)CD25 (+)CD127 (low/-) T cells: a more specific Treg population in human peripheral blood.

    Yu, Ning; Li, Xiaomei; Song, Weiya; Li, Dongmei; Yu, Daliang; Zeng, Xiaofeng; Li, Mengtao; Leng, Xiaomei; Li, Xiangpei

    2012-12-01

    The quantitative identification and enrichment of viable regulatory T cells (Treg) requires reliable surface markers that are selectively expressed on Treg. Foxp3 is the accepted marker of nTreg, but it cannot be used to isolate cells for functional studies. In this study, we compared four staining profiles of Treg, including CD4(+)CD25(high) T cells, CD4(+)CD39(+) T cells, CD4(+)CD73(+) T cells, and CD4(+)CD25(+)CD127(low/-) T cells. We found that CD4(+)CD25(+)CD127(low/-) T cells expressed the highest level of Foxp3 and had the strongest correlation with CD4(+)CD25(+)Foxp3(+) T cells, the accepted identifying characteristics for "real" nTreg cells. Moreover, functional data showed that CD4(+)CD25(+)CD127(low/-) T cells could effectively suppress the proliferation of CD4(+)CD25(-) T cells, suggesting that compared with the other three populations, CD4(+)CD25(+)CD127(low/-) T cells best fit the definition of naturally occurring regulatory T cells in human peripheral blood. Finally, we showed that CD4(+)CD25(+)CD127(low/-) can be used to quantitate Treg cells in individuals with systemic lupus erythematosus supporting the use of CD4(+)CD25(+)CD127(low/-) to identify human Treg cells. PMID:22752562

  17. A time-of-flight detector for thermal neutrons from radiotherapy Linacs

    Conti, V. [Universita degli Studi di Milano and INFN di Milano (Italy)], E-mail: conti.Valentina@gmail.com; Bartesaghi, G. [Universita degli Studi di Milano and INFN di Milano (Italy); Bolognini, D.; Mascagna, V.; Perboni, C.; Prest, M.; Scazzi, S. [Universita dell' Insubria, Como and INFN di Milano (Italy); Mozzanica, A. [Universita degli Studi di Brescia and INFN sezione di Pavia (Italy); Cappelletti, P.; Frigerio, M.; Gelosa, S.; Monti, A.; Ostinelli, A. [Fisica Sanitaria, Ospedale S. Anna di Como (Italy); Giannini, G.; Vallazza, E. [INFN, sezione di Trieste and Universita degli Studi di Trieste (Italy)

    2007-10-21

    Boron Neutron Capture Therapy (BNCT) is a therapeutic technique exploiting the release of dose inside the tumour cell after a fission of a {sup 10}B nucleus following the capture of a thermal neutron. BNCT could be the treatment for extended tumors (liver, stomach, lung), radio-resistant ones (melanoma) or tumours surrounded by vital organs (brain). The application of BNCT requires a high thermal neutron flux (>5x10{sup 8}ncm{sup -2}s{sup -1}) with the correct energy spectrum (neutron energy <10keV), two requirements that for the moment are fulfilled only by nuclear reactors. The INFN PhoNeS (Photo Neutron Source) project is trying to produce such a neutron beam with standard radiotherapy Linacs, maximizing with a dedicated photo-neutron converter the neutrons produced by Giant Dipole Resonance by a high energy (>8MeV) photon beam. In this framework, we have developed a real-time detector to measure the thermal neutron time-of -flight to compute the flux and the energy spectrum. Given the pulsed nature of Linac beams, the detector is a single neutron counting system made of a scintillator detecting the photon emitted after the neutron capture by the hydrogen nuclei. The scintillator signal is sampled by a dedicated FPGA clock thus obtaining the exact arrival time of the neutron itself. The paper will present the detector and its electronics, the feasibility measurements with a Varian Clinac 1800/2100CD and comparison with a Monte Carlo simulation.

  18. Study of the improvement of TLD cards for personal neutron dosimetry

    Rabie, N.; Hassan, G. M.; El-Sersy, A. R.; Ezzat, M.

    In this work, personal thermoluminescence dosimeter (TLD) cards type of GN-6770 (holder type 8806) from Harshaw were used for personal neutron dosimetry. The response of the dosimeters has been determined in terms of the personal absorbed dose and personal dose equivalent for different neutron energy components, based on the recommendations of ICRP-60 and ICRU-49. Neutron irradiation was performed using a 5 mCi Am-Be neutron source. The TLD reader, type Harshaw 6600, was installed and calibrated for accurate neutron doses equivalent to gamma-ray doses. It was found that fast neutron doses measured by TLD (badges or cards) are in agreement with those measured by neutron TE (tissue equivalent gas) ionization chambers and neutron monitors. Thermal neutron doses measured by TLD cards were overestimated when compared with those measured by neutron monitors. Additional Cd was used to reduce thermal neutron doses to be in agreement with actual thermal doses. Other configurations for TLD crystals are also suggested for accurate thermal neutron dose measurements.

  19. Commissioning of the 1.4 Mev/u High Current Heavy Ion Linac at Gsi

    Barth, W

    2000-01-01

    The disassembly of the Unilac prestripper linac of the Wideroe type took place at the beginning of 1999. An increase of more than two orders of magnitude in particle number for the most heavy elements in the SIS had to be gained. Since that time the new High Current Injector (HSI) consisting of H-type RFQ and DTL-structures for dual beam operation was installed and successfully commissioned. The High Charge Injector (HLI) supplied the main linac during that time. Simultaneously conditioning and running in of the rf-transmitters and rf-structures were done. The HSI commissioning strategy included beam investigation after each transport and acceleration section, using a versatile diagnostic test stand. Results of the extensive commissioning measurements (e.g. transverse emittance, bunch width, beam transmission) behind LEBT, RFQ, Super Lens, IH tank I and II and stripping section will be discussed. An 40Ar1+ beam coming from a MUCIS ion source was used to fill the linac up to the theoretical space charge limit....

  20. Advances in neutron tomography

    W Treimer

    2008-11-01

    In the last decade neutron radiography (NR) and tomography (NCT) have experienced a number of improvements, due to the well-known properties of neutrons interacting with matter, i.e. the low attenuation by many materials, the strong attenuation by hydrogenous constituent in samples, the wavelength-dependent attenuation in the neighbourhood of Bragg edges and due to better 2D neutron detectors. So NR and NCT were improved by sophisticated techniques that are based on the attenuation of neutrons or on phase changes of the associated neutron waves if they pass through structured materials. Up to now the interaction of the neutron spin with magnetic fields in samples has not been applied to imaging techniques despite the fact that it was proposed many years ago. About ten years ago neutron depolarization as imaging signal for neutron radiography or tomography was demonstrated and in principle it works. Now one can present much improved test experiments using polarized neutrons for radiographic imaging. For this purpose the CONRAD instrument of the HMI was equipped with polarizing and analysing benders very similar to conventional scattering experiments using polarized neutrons. Magnetic fields in different coils and in samples (superconductors) at low temperatures could be visualized. In this lecture a summary about standard signals (attenuation) and the more `sophisticated' imaging signals as refraction, small angle scattering and polarized neutrons will be given.

  1. Neutron structural biology

    Niimura, Nobuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Neutron diffraction provides an experimental method of directly locating hydrogen atoms in protein which play important roles in physiological functions. However, there are relatively few examples of neutron crystallography in biology since it takes a lot of time to collect a sufficient number of Bragg reflections due to the low flux of neutrons illuminating the sample. In order to overcome the flux problem, we have successfully developed the neutron IP, where the neutron converter, {sup 6}Li or Gd, was mixed with a photostimulated luminescence material on flexible plastic support. Neutron Laue diffraction 2A data from tetragonal lysozyme were collected for 10 days with neutron imaging plates, and 960 hydrogen atoms in the molecule and 157 bound water molecules were identified. These results explain the proposed hydrolysis mechanism of the sugar by the lysozyme molecule and that lysozyme is less active at pH7.0. (author)

  2. Neutron response study

    Neutron response of the albedo type dosimeter is strongly dependent on the energy of the incident neutrons as well as the moderating material on the backside of the dosimeter. This study characterizes the response of the Hanford dosimeter for a variety of neutron energies for both a water and Rando phantom (a simulated human body consisting of an actual human skeleton with plastic for body muscles and certain organs). The Hanford dosimeter response to neutrons of different energies is typical of albedo type dosimeters. An approximate two orders of magnitude difference in response is observed between neutron energies of 100 keV and 10 MeV. Methods were described to compensate for the difference in dosimeter response between a laboratory neutron spectrum and the different spectra encountered at various facilities in the field. Generally, substantial field support is necessary for accurate neutron dosimetry

  3. Neutron polarisation for ISIS

    Scattering experiments using polarised thermal and cold neutron beams have made important contributions to condensed matter physics, particularly to the understanding of atomic magnetism. This has been largely due to the vigorous efforts made at reactor institutes to develop polarised beam technology; their success in this enterprise is now paying handsome dividends. Progress in developing comparable techniques for pulsed neutron sources has been slower, largely due to the greater practical difficulties associated with polarising higher energy neutrons. However, there has been some advance, and this has now provided clarification into the best ways of integrating the various polarising devices into pulsed source spectrometers. The status of polarised neutron spectrometers at pulsed neutron sources is reviewed. The paper deals with three main topics, the scientific relevance of polarised neutron scattering experiments, a discussion of the properties of neutron polarisers, emphasising their strengths and limitations, and the integration of polarisers into a range of ISIS pulsed source spectrometers. (author)

  4. High-energy excited states in {sup 98}Cd

    Braun, Norbert; Blazhev, Andrey; Jolie, Jan [Institut fuer Kernphysik, Universitaet Koeln (Germany); Boutachkov, Plamen; Gorska, Magda; Grawe, Hubert; Pietri, Stephane [GSI, Darmstadt (Germany); Brock, Tim; Nara Singh, B.S.; Wadsworth, Robert [Department of Physics, University of York, York (United Kingdom); Liu, Zhong [University of Edinburgh, Edinburgh (United Kingdom)

    2009-07-01

    Studies of isomerism in the proton-rich N {approx_equal}Z nuclei around {sup 100}Sn give important insights into the role of proton-neutron pairing and also serve as testing grounds for nuclear models. In summer 2008, an experiment on {sup 96,97,98}Cd was performed using the FRS fragment separator and the RISING germanium array at GSI. These exotic nuclei of interest were produced using fragmentation of a 850 MeV/u {sup 124}Xe beam on a 4 g/cm{sup 2} {sup 9}Be target and finally implanted into an active stopper consisting of 9 double-sided silicon strip detectors. In {sup 98}Cd, a new high-energy isomeric transition was identified. Preliminary results on {sup 98}Cd are presented and their implications for the high-excitation level scheme are discussed.

  5. Design of a neutron activation system around a DD neutron generator by an analytical method and Monte Carlo simulation

    (LW), Beryllium (Be), Beryllium Oxide (BeO), and many shielding materials for gamma and fast neutrons have been studied (Boron Carbide (CB4), Borated Polyethylene, Lead. (Pb) Enriched Lithium Fluoride (6LiF), Cadmium (Cd), Graphite (G), Aluminum (Al)). This study concluded with an optimal configuration for an irradiation facility based on D-D NG for NAA and PGNAA achieving 1x107 N cm-2 s-1 thermal neutrons for internal configuration.

  6. Preliminary energy-filtering neutron imaging with time-of-flight method on PKUNIFTY: A compact accelerator based neutron imaging facility at Peking University

    Wang, Hu; Zou, Yubin; Wen, Weiwei; Lu, Yuanrong; Guo, Zhiyu

    2016-07-01

    Peking University Neutron Imaging Facility (PKUNIFTY) works on an accelerator-based neutron source with a repetition period of 10 ms and pulse duration of 0.4 ms, which has a rather low Cd ratio. To improve the effective Cd ratio and thus improve the detection capability of the facility, energy-filtering neutron imaging was realized with the intensified CCD camera and time-of-flight (TOF) method. Time structure of the pulsed neutron source was firstly simulated with Geant4, and the simulation result was evaluated with experiment. Both simulation and experiment results indicated that fast neutrons and epithermal neutrons were concentrated in the first 0.8 ms of each pulse period; meanwhile in the period of 0.8-2.0 ms only thermal neutrons existed. Based on this result, neutron images with and without energy filtering were acquired respectively, and it showed that detection capability of PKUNIFTY was improved with setting the exposure interval as 0.8-2.0 ms, especially for materials with strong moderating capability.

  7. Haptoglobin and CD163

    Madsen, M; Graversen, Jonas Heilskov; Moestrup, S K

    2001-01-01

    The plasma protein haptoglobin and the endocytic hemoglobin receptor HbSR/CD163 are key molecules in the process of removing hemoglobin released from ruptured erythrocytes. Hemoglobin in plasma is instantly bound with high affinity to haptoglobin--an interaction leading to the recognition of the ...

  8. Capture analysis of element content of a substance with other neutron methods

    Full text: Neutron analysis method of determining element composition have found wide range of applications in industry thanks to different types of interaction of neutron with substances /1/. With the aim of widening the range of problems to be solved, on the basis of the device /2/ for determining the element content of substance, possibilities of combining the method based on the use of neutron capture gamma-ray spectrometry with other neutron methods, in particular neutron activation analysis and neutron absorption analysis were studied. In this radionuclide source (252Cf) with the yield of 1,5 x 107 neutron/sec is used. By means of using neutron capture gamma radiation spectrometry the possibilities of determining some elements (H, B, N, S etc. ), which are not determined by very widely used method, activation analysis. These elements can be determined by both the semiconductor and scintillation detectors with parameters fitting the manufacturing requirements. And for a number of elements ( B, Cl, Cd, Sm, Gd) very high limits of determination ( up to 10- 5 %) are possible using semiconductor Ge (Li) -detectors with high resolution. Possibility of determination of some 'well' activated elements ( K, Al, Fe, Mn, Ti, Sc etc.) in samples of ore and products of their processing using the neutron-activation analysis. For 1 hour of irradiation on the experimental device quite accurate analytical peak, of these elements are obtained, allowing to determine them qualitatively. However, with decreasing neutron yield of radionuclide source it becomes more difficult to achieve the necessary parameters both in neutron capture and activation analysis. Experimental works on determination of some elements with large cross-sections of capture ( B, Cd, Sm ) by absorption of neutrons in the investigated substance, i.e. using the neutron absorption analysis method with absence of other large capture cross section elements in the samples being studied

  9. Curved neutron guide

    The principle of the curved neutron guide is to transport neutrons far away from the reactor core with as minimum particle loss as possible. After a series of total reflection,the neutron beam is no longer visible from the reactor core and consequently, gamma radiations and fast neutrons emitted from the core are scattered by the walls of the guide and absorbed by the biological shielding set around the guide. The curved neutron guide provides a high-quality beam of slow neutrons. The first chapter deals with the theoretical concept of curved guide, we have determined the parameters for the setting of such a guide in the EL3 reactor at Saclay (France). The different tolerances on the state the surface, on the alignment of the different parts of the guide, on the waving of the guide wall have been assessed. The second chapter presents the technical solution chosen that complies to all the required specifications. The curved neutron guide has been designed for neutrons with wavelength of 4 Angstroms, it is 29 m long, has a bending radius of 835 m and is composed of 87 rectangular components made of glass plates on which a 1500 angstrom thick layer of nickel has been deposited. Each component is set with a fixed angle of (4±0.25)*10-4 radians from the previous component in order to form the bending radius. The last chapter is dedicated to the neutron flux measurement made at the end of the neutron guide

  10. The biological difference between CD13+CD133+ and CD13¬CD133¬liver cancer cells and its clinical significance

    Shi-long JIN; Zhong-rong HUANG; Chen, Hua; Tian-wu YU; Cao, Hong; Yun-quan LONG; Zhou, Jian; Li, He; Yi GOU; Li, Yuan; Liao, Juan

    2013-01-01

    Objective To compare the biological difference between CD13+CD133+ and CD13-CD133- hepatocellular carcinoma (HCC) cells in HuH7 cell line and its clinical significance. Methods The status of proliferation, phase of the cell cycle, tumor formation in vivo, differentiation, and their chemoresistance to 5-FU and pirarubicin of CD13+CD133+ and CD13-CD133-HCC cells were studied to analyze the clinical implication of CD13+CD133+HCC cell subset. Results The proliferation rate of CD13+CD133+HCC cells...

  11. CdS/CdSSe quantum dots in glass matrix

    R S Sonawane; S D Naik; S K Apte; M V Kulkarni; B B Kale

    2008-06-01

    The compositions containing 55 and 60% of silica have been formulated for preparation of glass filters having sharp cut-off at 475 and 575 nm. To achieve cut-off at these wavelengths, the glasses have been doped with CdS/CdSSe and melted at 1200–1300°C. The glass samples were transparent and pale yellow in colour due to presence of CdS/CdSSe tiny nano crystal (Q-dots). in situ growth of CdS/CdSSe nano crystals imparts the yellow/orange/red colour to these glasses. Optical study shows that as prepared glasses have optical cut-off in the range 350–370 nm. The linear crystal growth of CdS/CdSSe in glasses exhibits red shift in optical cut-off. The optical filter having cut-off at 475 nm can be prepared by doping CdS and cut-off filter of wavelength 575 nm by CdSSe. The TEM results show that the CdS/CdSSe nano crystals (Q-dots) ranging from 2–5 nm are uniformly distributed into the glass matrix.

  12. Pulsed neutron porosity logging system

    An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations and, during the bursts, the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity

  13. Neutron chopper development at LANSCE

    Progress is reported on neutron chopper systems for the Los Alamos Neutron Scattering Center pulsed spallation neutron source. This includes the development of 600+ Hz active magnetic bearing neutron chopper and a high speed control system designed to operate with the Proton Storage Ring to phase the chopper to the neutron source. 5 refs., 3 figs

  14. Status of spallation neutron source

    Oyama, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    Existing and planned facilities using proton accelerator driven spallation neutron source are reviewed. These include new project of neutron science proposed from Japan Atomic Energy Research Institute. The present status of facility requirement and accelerator technology leads us to new era of neutron science such as neutron scattering research and nuclear transmutation study using very intense neutron source. (author)

  15. Precursor phenomenon of martensitic transformation in Au-49.5at%Cd alloy

    Phonon softening was observed in the parent phase of a AuCd alloy which t=forms from the β2(B2) parent to ζ2' (trigonal) martensitic. Since Cd strongly absorbs neutrons, the isotope 114Cd was used in preparing the single crystal for the measurements. The [ζζ0]TA2 phonon branch was measured and found to be anomalously low. A minimum is present at ζ = 0.35 which softens with decreasing temperature towards Ms. The results are consistent with the model proposed by Ohba et al. based upon a crystallographic study of the ζ2' phase

  16. IL-2 and IL-15 regulate CD154 expression on activated CD4 T cells

    Skov, S; Bonyhadi, M; Odum, Niels; Ledbetter, J A

    2000-01-01

    The cellular and humoral immune system is critically dependent upon CD40-CD154 (CD40 ligand) interactions between CD40 expressed on B cells, macrophages, and dendritic cells, and CD154 expressed primarily on CD4 T cells. Previous studies have shown that CD154 is transiently expressed on CD4 T cel...

  17. Rabbit CD200R binds host CD200 but not CD200-like proteins from poxviruses

    Akkaya, Munir; Kwong, Lai-Shan; Akkaya, Erdem; Hatherley, Deborah; Barclay, A. Neil

    2016-01-01

    CD200 is a widely distributed membrane protein that gives inhibitory signals through its receptor (CD200R) on myeloid cells. CD200 has been acquired by herpesviruses where it has been shown to interact with host CD200R and downmodulate the immune system. It has been hypothesized that poxviruses have acquired CD200; but the potential orthologues show less similarity to their hosts. Myxoma virus M141 protein is a potential CD200 orthologue with a potent immune modulatory function in rabbits. Here, we characterized the rabbit CD200, CD200R and tested the CD200-like sequences for binding CD200R. No binding could be detected using soluble recombinant proteins, full length protein expressed on cells or myxoma virus infected cells. Finally, using knockdown models, we showed that the inhibitory effect of M141 on RAW 264.7 cells upon myxoma virus infection is not due to CD200R. We conclude that the rabbit poxvirus CD200-like proteins cause immunomodulation without utilizing CD200R. PMID:26590792

  18. Burnable neutron absorber element

    A burnable thermal neutron absorber element is described comprising: a zirconium alloy elongated tubular container having an inside diameter surface; hydrogen diffusion barrier means for limiting hydrogen diffusion from within the container into the zirconium alloy; a boron-containing burnable thermal neutron absorber material sealed within the zirconium alloy elongated container, the boron-containing burnable absorber material being in a particle form, the particles of absorber material being coated with a diffusion barrier material; zirconium hydride sealed within the zirconium alloy elongated container, the zirconium hydride being in a partially hydrided condition and having a H to Zr ratio on an atomic basis in the range of about 1.0 to about 1.8; the burnable thermal neutron absorber material and the zirconium hydride distributed along the length of the zirconium alloy elongated container; and the zirconium hydride acts as a neutron moderator thereby enhancing the neutron capture efficiency of the burnable thermal neutron absorber

  19. Burnable neutron absorber element

    Ferrari, H.M.

    1988-06-14

    A burnable thermal neutron absorber element is described comprising: a zirconium alloy elongated tubular container having an inside diameter surface; hydrogen diffusion barrier means for limiting hydrogen diffusion from within the container into the zirconium alloy; a boron-containing burnable thermal neutron absorber material sealed within the zirconium alloy elongated container, the boron-containing burnable absorber material being in a particle form, the particles of absorber material being coated with a diffusion barrier material; zirconium hydride sealed within the zirconium alloy elongated container, the zirconium hydride being in a partially hydrided condition and having a H to Zr ratio on an atomic basis in the range of about 1.0 to about 1.8; the burnable thermal neutron absorber material and the zirconium hydride distributed along the length of the zirconium alloy elongated container; and the zirconium hydride acts as a neutron moderator thereby enhancing the neutron capture efficiency of the burnable thermal neutron absorber.

  20. Biological effects of neutrons

    Although the occasion to be exposed to neutrons is rare in our life, except for nuclear accidents like in the critical accident at Tokai-mura in 1999, countermeasures against accident should be always prepared. In the Tokai-mura accident, residents received less than 21 mSv of neutrons and gamma rays. The cancer risks and fetal effects of low doses of neutrons were matters of concern among residents. The purpose of this program is to investigate the relative biological effectiveness (RBE) for leukemias, and thereby to assess risks of neutrons. Animal experiments are planed to obtain the following RBEs: (1) RBE for the induction of leukemias in mice and (2) RBE for effects on fetuses. Cyclotron fast neutrons (10 MeV) and electrostatic accelerator-derived neutrons (2 MeV) are used for exposure in this program. Furthermore, cytological and cytogenetic analyses will be performed. (author)

  1. Neutron sources and applications

    Price, D.L. [ed.] [Argonne National Lab., IL (United States); Rush, J.J. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

    1994-01-01

    Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications.

  2. Neutron sources and applications

    Review of Neutron Sources and Applications was held at Oak Brook, Illinois, during September 8--10, 1992. This review involved some 70 national and international experts in different areas of neutron research, sources, and applications. Separate working groups were asked to (1) review the current status of advanced research reactors and spallation sources; and (2) provide an update on scientific, technological, and medical applications, including neutron scattering research in a number of disciplines, isotope production, materials irradiation, and other important uses of neutron sources such as materials analysis and fundamental neutron physics. This report summarizes the findings and conclusions of the different working groups involved in the review, and contains some of the best current expertise on neutron sources and applications

  3. Gravitational neutron monochromator

    A new type of slow-neutron monochromator is described that is based on the interaction of slow neutrons with the earth's gravitational field. The monochromator is formed by three slit collimators placed along the neutron trajectory. The energy of the neutrons selected by the monochromator is set by vertical movement of any of the slit collimators. This scheme was used to create a gravitational monochromator on the 1000-meter path of the IBR-30 pulsed fast reactor at Dubna. It provides monochromatic neutrons with an energy resolution of 1.8% and measures the free-fall acceleration of neutrons with an error of 0.1% in the energy range of 0.0175-0.4223 eV

  4. Resonance neutron radiography

    The production of images by the use of neutrons having energies in the resonance region is described. Two-dimensional position-sensitive neutron detectors are used to produce transmission images using neutron time-of-flight techniques at the National Bureau of Standards' electron linac facility. Two types of detectors are described. The first is a crossed-wire proportional counter using 3He as the neutron-sensitive component. The second type utilizes a multichannel plate electron multiplier and a resistive anode readout. A lithium glass scintillator is the neutron-sensitive component in the latter detector. Resonance neutron radiography, using these detectors, has the capability of producing images with isotopic and chemical element discrimination in a complex matrix with a resolution of 1 mm or better. (Auth.)

  5. Active neutron instrumentation

    An introduction to neutron interactions in tissue and a discussion of pertinent nuetron cross-sections will be given. A brief description of the statistics of energy deposition due to interactions of neutron secondaries in tissue equivalent media is presented. Present and past techniques for measurement of neutron radiation fields are given with advantages and disadvantages in the light of legal limits and proposed changes in those requirements. Neutron dose measuring devices, such as the tissue equivalent proportional counter (TEPC) developed by Rossi, are discussed with emphasis on their response in varying neutron energy spectra. Techniques for determining neutron quality factors from TEPC response functions are discussed along with implications of possible new definitions of quality factor. A brief description of high-resolution spectrometry systems, which use hydrogen, methane and He-3 fill gases, is given with discussion of their limitations. Low resolution systems, such as multisphere spectrometers and activation foils, are also presented

  6. Measurement of thermal neutron spectra using LINAC in Japan Atomic Energy Research Institute (JAERI)

    The exact grasp of thermal neutron spectra in a core region is very important for obtaining accurate thermal neutron group constants in the calculation for the nuclear design of a reactor core. For the accurate grasp of thermal neutron spectra, the capability of thermal neutron spectra to describe the moderator cross-sections for thermal neutron scattering is a key factor. Accordingly, 0 deg angular thermal neutron spectra were measured by the time of flight (TOF) method using the JAERI LINAC as a pulsed neutron source, for light water system added with Cd and In, high temperature graphite system added with boron, and light water-natural uranium heterogeneous multiplication system among the reactor moderators of light water or graphite systems. First, the equations to give the time of flight and neutron flux by TOF method were analyzed, and several corrections were investigated, such as those for detector efficiency, background, the transmission coefficient of air and the Al window of a flight tube, mean emission time of neutrons, and the distortion effect of re-entrant hole on thermal neutron spectra. Then, the experimental system, results and calculation were reported for the experiments on the above three moderator systems. Finally, the measurement of fast neutron spectra in natural uranium system and that of the efficiency of a 6Li glass scintillator detector are described. (Wakatsuki, Y.)

  7. Soluble CD14 in periodontitis

    E.A. Nicu; M.L. Laine; S.A. Morre; U. van der Velden; B.G. Loos

    2009-01-01

    Lipopolysaccharide (LPS) binds to soluble (s)CD14. We investigated which factors contribute to variations in sCD14 levels in periodontitis, a chronic infectious disease of tooth-supporting tissues associated with endotoxemia and leading to inflammation and subsequently loss of teeth. The sCD14 level

  8. ATR neutron spectral characterization

    The Advanced Test Reactor (ATR) at INEL provides intense neutron fields for irradiation-effects testing of reactor material samples, for production of radionuclides used in industrial and medical applications, and for scientific research. Characterization of the neutron environments in the irradiation locations of the ATR has been done by means of neutronics calculations and by means of neutron dosimetry based on the use of neutron activation monitors that are placed in the various irradiation locations. The primary purpose of this report is to present the results of an extensive characterization of several ATR irradiation locations based on neutron dosimetry measurements and on least-squares-adjustment analyses that utilize both neutron dosimetry measurements and neutronics calculations. This report builds upon the previous publications, especially the reference 4 paper. Section 2 provides a brief description of the ATR and it tabulates neutron spectral information for typical irradiation locations, as derived from the more historical neutron dosimetry measurements. Relevant details that pertain to the multigroup neutron spectral characterization are covered in section 3. This discussion includes a presentation on the dosimeter irradiation and analyses and a development of the least-squares adjustment methodology, along with a summary of the results of these analyses. Spectrum-averaged cross sections for neutron monitoring and for displacement-damage prediction in Fe, Cr, and Ni are given in section 4. In addition, section4 includes estimates of damage generation rates for these materials in selected ATR irradiation locations. In section 5, the authors present a brief discussion of the most significant conclusions of this work and comment on its relevance to the present ATR core configuration. Finally, detailed numerical and graphical results for the spectrum-characterization analyses in each irradiation location are provided in the Appendix

  9. Neutrons and Nuclear Engineering

    Oak Ridge National Laboratory hosted two workshops in April 2007 relevant to nuclear engineering education. In the Neutron Stress, Texture, and Phase Transformation for Industry workshop (http://neutrons.ornl.gov/workshops/nst2/), several invited speakers gave examples of neutron stress mapping for nuclear engineering applications. These included John Root of National Research Council of Canada, Mike Fitzpatrick of the UK's Open University, and Yan Gao of GE Global Research on their experiences with industrial and academic uses of neutron diffraction. Xun-Li Wang and Camden Hubbard described the new instruments at ORNL that can be used for such studies. This was preceded by the Neutrons for Materials Science and Engineering educational symposium (http://neutrons.ornl.gov/workshops/edsym2007). It was directed to the broad materials science and engineering community based in universities, industry and laboratories who wish to learn what the neutron sources in the US can provide for enhancing the understanding of materials behavior, processing and joining. Of particular interest was the presentation of Donald Brown of Los Alamos about using 'Neutron diffraction measurements of strain and texture to study mechanical behavior of structural materials.' At both workshops, the ORNL neutron scattering instruments relevant to nuclear engineering studies were described. The Neutron Residual Stress Mapping Facility (NRSF2) is currently in operation at the High Flux Isotope Reactor; the VULCAN Engineering Materials Diffractometer will begin commissioning in 2008 at the Spallation Neutron Source. For characteristics of these instruments, as well as details of other workshops, meetings, capabilities, and research proposal submissions, please visit http://neutrons.ornl.gov. To submit user proposals for time on NRSF2 contact Hubbard at hubbardcratornl.gov

  10. Polysiloxane based neutron detectors

    Dalla Palma, Matteo

    2016-01-01

    In the last decade, neutron detection has been attracting the attention of the scientific community for different reasons. On one side, the increase in the price of 3He, employed in the most efficient and the most widely used neutron detectors. On the other side, the harmfulness of traditional xylene based liquid scintillators, used in extremely large volumes for the detection of fast neutrons. Finally, the demand for most compact and rough systems pushed by the increased popularity of neutro...