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Sample records for radiative widths neutron

  1. Distribution of total radiation widths for neutron resonances of Pt isotopes

    Directory of Open Access Journals (Sweden)

    Koehler P.E.

    2015-01-01

    Full Text Available High quality neutron capture and transmission data were measured on isotopically enriched 192,194,195,196Pt and natural Pt samples at ORELA. R-matrix analysis of this data revealed resonance parameters for 159, 413, 423, 258, and 11 neutron resonances for neutron energies below 5.0, 16.0, 7.5, 16.0, and 5.0 keV for 192,194,195,196,198Pt+n, respectively. Earlier analysis of data on reduced neutron widths, Γ0n, showed that the distributions of Γ0n for 192,194Pt deviate significantly from the Porter-Thomas distribution (PTD predicted by random matrix theory. In this contribution we report on preliminary results of the analysis of distribution of total radiation widths, Γγ, in 192,194,195,196Pt+n reactions. Comparison of experimental data with predictions made within the nuclear statistical model indicates that standard models of Photon Strength Functions (PSFs and Nuclear Level Density predict Γγ distributions which are too narrow. We found that satisfactory agreement between experimental and simulated distributions can be obtained only by a strong suppression of the PSFs at low γ-ray energies and/or by violation of the usual assumption that primary transitions from neutron resonances follow the PTD. The shape of PSFs needed for reproduction of our Γγ data also nicely reproduces spectra from several (n,γ experiments on the neighbor nuclide 198Au.

  2. What Do s- and p-Wave Neutron Average Radiative Widths Reveal

    Energy Technology Data Exchange (ETDEWEB)

    Mughabghab, S.F.

    2010-04-30

    A first observation of two resonance-like structures at mass numbers 92 and 112 in the average capture widths of the p-wave neutron resonances relative to the s-wave component is interpreted in terms of a spin-orbit splitting of the 3p single-particle state into P{sub 3/2} and P{sub 1/2} components at the neutron separation energy. A third structure at about A = 124, which is not correlated with the 3p-wave neutron strength function, is possibly due to the Pygmy Dipole Resonance. Five significant results emerge from this investigation: (i) The strength of the spin-orbit potential of the optical-model is determined as 5.7 {+-} 0.5 MeV, (ii) Non-statistical effects dominate the p-wave neutron-capture in the mass region A = 85 - 130, (iii) The background magnitude of the p-wave average capture-width relative to that of the s-wave is determined as 0.50 {+-} 0.05, which is accounted for quantitatively in tenns of the generalized Fermi liquid model of Mughabghab and Dunford, (iv) The p-wave resonances arc partially decoupled from the giant-dipole resonance (GDR), and (v) Gamma-ray transitions, enhanced over the predictions of the GDR, are observed in the {sup 90}Zr - {sup 98}Mo and Sn-Ba regions.

  3. Study of the fluctuations of the partial and total radiative widths by neutron capture resonance method; Etude des fluctuations des largeurs radiatives partielles et totales par la capture des neutrons de resonance

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, V.D. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    Radiative capture experiments by neutron time-of-flight methods have been made for following studies: distribution of partial radiative widths, effects of correlation between different radiative transitions, fluctuations of total radiative widths {gamma}{sub {gamma}} from resonance to resonance, variation of {gamma}{sub {gamma}} with number of mass and the search for the existence of potential capture. Also, some other experiments with the use of neutron capture gamma-rays spectra have been investigated. (author) [French] Par la capture des neutrons de resonance dont les energies sont selectionnees a l'aide de la technique du temps de vol, differents types d'experiences ont ete realisees concernant les etudes des distributions des largeurs radiatives partielles, des effets de correlation entre differentes voies de desexcitation, de la fluctuation des largeurs radiatives totales {gamma}{sub {gamma}} de resonance a resonance, de la variation de la quantite {gamma}{sub {gamma}} en fonction du nombre de masse et de la mise en evidence de l'existence du processus de capture potentielle. Quelques autres applications de l'emploi du spectre de rayons gamma ont egalement ete presentees. (auteur)

  4. Average radiation widths and the giant dipole resonance width

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, M.; Thielemann, F.K.

    1982-11-01

    The average E1 radiation width can be calculated in terms of the energy Esub(G) and width GAMMAsub(G) of the Giant Dipole Resonance (GDR). While various models can predict Esub(G) quite reliably, the theoretical situation regarding ..lambda..sub(G) is much less satisfactory. We propose a simple phenomenological model which is able to provide GAMMAsub(G) values in good agreement with experimental data for spherical or deformed intermediate and heavy nuclei. In particular, this model can account for shell effects in GAMMAsub(G), and can be used in conjunction with the droplet model. The GAMMAsub(G) values derived in such a way are used to compute average E1 radiation widths which are quite close to the experimental values. The method proposed for the calculation of GAMMAsub(G) also appears to be well suited when the GDR characteristics of extended sets of nuclei are required, as is namely the case in nuclear astrophysics.

  5. Average radiation widths of levels in natural xenon isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Noguere, G., E-mail: gilles.noguere@cea.fr [CEA, DEN, Cadarache, F-13108 Saint Paul les Durance (France); Litaize, O.; Archier, P.; De Saint Jean, C. [CEA, DEN, Cadarache, F-13108 Saint Paul les Durance (France); Mutti, P. [Institut Laue-Langevin, F-38042 Grenoble (France)

    2011-11-15

    Average radiation widths <{Gamma}{sub {gamma}>} for the stable xenon isotopes have been estimated using neutron resonance spectroscopic information deduced from high-resolution capture and transmission data measured at the electron linear accelerator GELINA of the Institute for Reference Materials and Measurements (IRMM) in Geel, Belgium. The combination of conventional Neutron Resonance Shape Analysis techniques (NRSA) with high-energy model calculations in a simple Bayesian learning method permit to calculate a consistent local systematic in the xenon's mass region (Z=54) from A=124 to A=136.

  6. Radiative widths of neutral kaon excitations

    Indian Academy of Sciences (India)

    Sunil V Somalwar; KTeV Collaboration

    2004-03-01

    We observe 147 events of the axial vector pair $K_{1} (1270) - K_{1} (1400)$ produced in the Coulomb field of a Pb target and measure the radiative widths $ (K_{1} (1400) → K^{0} + ) = 280.8 ± 23.2$ (stat.) $± (40.4)$ (syst.) keV and $ (K_{1} (1270) → K^{0} + ) = 73.2 ± 6.1$ (stat.) $± 28.3$ (syst.) keV. These first measurements are lower than the quark-model predictions. We also place upper limits on the radiative widths for $K^{*} (1410)$ and $K_{2}^{*} (1430)$ and find that the letter is very small in accord with $SU(3)$ invariance in the naive quark model.

  7. The optimum choice of gate width for neutron coincidence counting

    Science.gov (United States)

    Croft, S.; Henzlova, D.; Favalli, A.; Hauck, D. K.; Santi, P. A.

    2014-11-01

    In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using 252Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.

  8. The optimum choice of gate width for neutron coincidence counting

    Energy Technology Data Exchange (ETDEWEB)

    Croft, S., E-mail: crofts@ornl.gov [Safeguards and Security Technology (SST), Global Nuclear Security Technology Divisions, PO Box 2008, Building 5700, MS-6166, Oak Ridge, TN 37831-6166 (United States); Henzlova, D.; Favalli, A.; Hauck, D.K.; Santi, P.A. [Safeguards Science and Technology Group (NEN-1), Nuclear Engineering and Nonproliferation Division, MS-E540, Los Alamos, NM 87545 (United States)

    2014-11-11

    In the measurement field of international nuclear safeguards, passive neutron coincidence counting is used to quantify the spontaneous fission rate of certain special nuclear materials. The shift register autocorrelation analysis method is the most commonly used approach. However, the Feynman-Y technique, which is more commonly applied in reactor noise analysis, provides an alternative means to extract the correlation information from a pulse train. In this work we consider how to select the optimum gate width for each of these two time-correlation analysis techniques. The optimum is considered to be that which gives the lowest fractional precision on the net doublets rate. Our theoretical approach is approximate but is instructional in terms of revealing the key functional dependence. We show that in both cases the same performance figure of merit applies so that common design criteria apply to the neutron detector head. Our prediction is that near optimal results, suitable for most practical applications, can be obtained from both techniques using a common gate width setting. The estimated precision is also comparable in the two cases. The theoretical expressions are tested experimentally using {sup 252}Cf spontaneous fission sources measured in two thermal well counters representative of the type in common use by international inspectorates. Fast accidental sampling was the favored method of acquiring the Feynman-Y data. Our experimental study confirmed the basic functional dependences predicted although experimental results when available are preferred. With an appropriate gate setting Feynman-Y analysis provides an alternative to shift register analysis for safeguards applications which is opening up new avenues of data collection and data reduction to explore.

  9. Optimal gate-width setting for passive neutrons multiplicity counting

    Energy Technology Data Exchange (ETDEWEB)

    Croft, Stephen [Los Alamos National Laboratory; Evans, Louise G [Los Alamos National Laboratory; Schear, Melissa A [Los Alamos National Laboratory

    2010-01-01

    When setting up a passive neutron coincidence counter it is natural to ask what coincidence gate settings should be used to optimize the counting precision. If the gate width is too short then signal is lost and the precision is compromised because in a given period only a few coincidence events will be observed. On the other hand if the gate is too large the signal will be maximized but it will also be compromised by the high level of random pile-up or Accidental coincidence events which must be subtracted. In the case of shift register electronics connected to an assay chamber with an exponential dieaway profile operating in the regime where the Accidentals rate dominates the Reals coincidence rate but where dead-time is not a concern, simple arguments allow one to show that the relative precision on the net Reals rate is minimized when the coincidence gate is set to about 1.2 times the lie dieaway time of the system. In this work we show that making the same assumptions it is easy to show that the relative precision on the Triples rates is also at a minimum when the relative precision of the Doubles (or Reals) is at a minimum. Although the analysis is straightforward to our knowledge such a discussion has not been documented in the literature before. Actual measurement systems do not always behave in the ideal we choose to model them. Fortunately however the variation in the relative precision as a function of gate width is rather flat for traditional safeguards counters and so the performance is somewhat forgiving of the exact choice. The derivation further serves to delineate the important parameters which determine the relative counting precision of the Doubles and Triples rates under the regime considered. To illustrate the similarities and differences we consider the relative standard deviation that might be anticipated for a passive correlation count of an axial section of a spent nuclear fuel assembly under practically achievable conditions.

  10. Measurement of radiative widths at COMPASS

    CERN Document Server

    Krämer, Markus

    2014-01-01

    COMPASS is a multipurpose fixed-target experiment at the CERN SPS, which addresses a wide variety of physic topics, in particular the structure and spectroscopy of hadrons. Diffractive dissociation of pions on nuclear targets allows for clean access to the light meson spectrum. In addition meson production can be studied in pion-photon reactions via the Primakoff effect, where high-energetic pions react with the quasi-real photon field surrounding the target nuclei. At low pion-photon center-of-mass energies, these reactions are governed by chiral dynamics and contain information relevant for chiral perturbation theory. At higher energies, resonances are produced and their radiative coupling is investigated. During a short run using a 190GeV $\\pi^-$ beam and a lead target in the year 2004, 3 million exclusive $\\pi^-\\pi^-\\pi^+$ events in the region of small squared four-momentum transfer, i.e. t' < 0:01GeV$^2$=c$^2$, have been recorded. At very low t' < 0:001GeV$^2$=c$^2$, the contribution from electroma...

  11. Reduced neutron widths in the nuclear data ensemble: Experiment and theory do not agree

    CERN Document Server

    Koehler, P E

    2010-01-01

    I have analyzed reduced neutron widths ($\\Gamma_{n}^{0}$) for the subset of 1245 resonances in the nuclear data ensemble (NDE) for which they have been reported. Random matrix theory (RMT) predicts for the Gaussian orthogonal ensemble (GOE) that these widths should follow a $\\chi ^{2}$ distribution having one degree of freedom ($\

  12. Extraction of radiative decay width for the non-strange partner of Theta^+

    CERN Document Server

    Azimov, Ya I; Polyakov, M V; Strakovsky, I I; Azimov, Ya.

    2005-01-01

    Using the results of the GRAAL collaboration on the \\eta photoproduction from the neutron target, we attempt to extract the partial radiative width of the possible new nucleon resonance N^*(1675). The obtained estimates support this resonance to be a very attractive candidate for the non-strange member of the exotic antidecuplet of baryons -- a partner of the \\Theta^+ pentaquark. Our phenomenological value for the transition magnetic moment \\mu(n^* n), appears to be in good agreement with predictions of the Chiral Quark Soliton Model.

  13. Neutron responsive self-powered radiation detector

    Science.gov (United States)

    Brown, Donald P.; Cannon, Collins P.

    1978-01-01

    An improved neutron responsive self-powered radiation detector is disclosed in which the neutron absorptive central emitter has a substantially neutron transmissive conductor collector sheath spaced about the emitter and the space between the emitter and collector sheath is evacuated.

  14. Solar Neutrons and the Earth's Radiation Belts.

    Science.gov (United States)

    Lingenfelter, R E; Flamm, E J

    1964-04-17

    The intensity and spectrum of solar neutrons in the vicinity of the earth are calculated on the assumption that the low-energy protons recently detected in balloon and satellite flights are products of solar neutron decay. The solar-neutron flux thus obtained exceeds the global average cosmic-ray neutron leakage above 10 Mev, indicating that it may be an important source of both the inner and outer radiation belts. Neutron measurements in the atmosphere are reviewed and several features of the data are found to be consistent with the estimated solar neutron spectrum.

  15. Comment on "Distribution of Partial Neutron Widths for Nuclei Close to a Maximum of the Neutron Strength Function"

    OpenAIRE

    Koehler, P. E.; Bečvář, F.; Krtička, M.; Harvey, J. A.; Guber, K. H.

    2011-01-01

    A recent Letter attempted to reconcile the disagreement between neutron resonance data and random matrix theory (RMT). To this end, a new formula was derived for transforming measured ({\\Gamma}_{{\\lambda}n}) to reduced ({\\Gamma}_{{\\lambda}n}^0) neutron widths for s-wave resonances ({\\lambda}=1,2,...) in nuclides near peaks of the s-wave neutron strength function. In this Comment, we show that such a rescaling would not, in general, be expected to reconcile the type of disagreement observed, a...

  16. Comment on "Distribution of Partial Neutron Widths for Nuclei Close to a Maximum of the Neutron Strength Function"

    CERN Document Server

    Koehler, P E; Krtička, M; Harvey, J A; Guber, K H

    2011-01-01

    A recent Letter attempted to reconcile the disagreement between neutron resonance data and random matrix theory (RMT). To this end, a new formula was derived for transforming measured ({\\Gamma}_{{\\lambda}n}) to reduced ({\\Gamma}_{{\\lambda}n}^0) neutron widths for s-wave resonances ({\\lambda}=1,2,...) in nuclides near peaks of the s-wave neutron strength function. In this Comment, we show that such a rescaling would not, in general, be expected to reconcile the type of disagreement observed, and demonstrate that indeed it does not for the specific cases in question. Hence, the disagreements between RMT and these data remain.

  17. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    Energy Technology Data Exchange (ETDEWEB)

    Scott Wilde, Raymond Keegan

    2008-07-01

    The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

  18. Internal and external radiative widths in the combined R-matrix and potential model formalism

    CERN Document Server

    Mukhamedzhanov, A M; Bertulani, C A; Hao, T V Nhan

    2016-01-01

    Using the $R$-matrix approach we calculate the radiative width for a resonance decaying to a bound state through electric dipole, $E1$, transitions. The total radiative width is determined by the interference of the nuclear internal and external radiative width amplitudes. For a given channel radius the external radiative width amplitude is model independent and is determined by the asymptotic normalization coefficient (ANC) of the bound state to which the resonance decays. It also depends on the partial resonance width. To calculate the internal radiative width amplitude we show that a single particle potential model is appropriate. We compare our results with a few experimental data.

  19. Parameters of the best approximation of reduced neutron widths distribution. Actinides

    CERN Document Server

    Sukhovoj, A M

    2011-01-01

    The data of ENDF/B-VII library on reduced neutron widths for nuclei 231Pa, 232Th, 233,234,235,236,238U, 237Np, 239,240,241,242Pu, 241,243Am and 243Cm (including p-resonances of 232Th, 238U, 239Pu) in form of cumulative sums in function on Gamma0n/ were approximated by variable number K of partial items 0neutron amplitude, its dispersion and portion of contribution of part of widths of distribution number K in their total sum. The problems of their determination from distributions of different number of squares of normally distributed random values with variable threshold of loss of some part of the lowest widths values were studied. It was obtained for some part of neutron resonances that their mean amplitudes can considerably differ from zero value, and dispersions - from mean widths. And it is worth while to perform any quantitative analysis of widths distributions by means of comparison of different model notions with obligatory estimation of random ...

  20. Temperature dependence of a spreading width of giant dipole resonance in neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Vdovin, A.I.; Storozhenko, A.N

    2003-07-14

    A temperature dependence of the spreading width of a giant dipole resonance is studied in the framework of the Quasiparticle-Phonon Model extended to finite temperature using a formalism of the Thermo Field Dynamics. Numerical calculations are performed for {sup 120}Sn and the neutron-rich double-magic isotope {sup 132}Sn It is found that the dispersion of the E1 strength function {sigma} increases with temperature.

  1. Data on Neutron Widths do not refute Random--Matrix Theory

    CERN Document Server

    Shriner, J F; Mitchell, G E

    2012-01-01

    Recent analyses of the distribution of reduced neutron widths in the Nuclear Data Ensemble (NDE) and in the Pt isotopes claim strong disagreement with predictions of random--matrix theory. Using numerical simulations we identify the causes for the apparent disagreement. For the NDE it is a strong bias inherent in the method of analysis. In the Pt isotopes, it is likely to be a threshold state.

  2. Radiation shielding for neutron guides

    Science.gov (United States)

    Ersez, T.; Braoudakis, G.; Osborn, J. C.

    2006-11-01

    Models of the neutron guide shielding for the out of bunker guides on the thermal and cold neutron beam lines of the OPAL Reactor (ANSTO) were constructed using the Monte Carlo code MCNP 4B. The neutrons that were not reflected inside the guides but were absorbed by the supermirror (SM) layers were noted to be a significant source of gammas. Gammas also arise from neutrons absorbed by the B, Si, Na and K contained in the glass. The proposed shielding design has produced compact shielding assemblies. These arrangements are consistent with safety requirements, floor load limits, and cost constraints. To verify the design a prototype was assembled consisting of 120 mm thick Pb(96%)Sb(4%) walls resting on a concrete block. There was good agreement between experimental measurements and calculated dose rates for bulk shield regions.

  3. Effects of the neutron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Alcober, V. (Junta de Energia Nuclear, Madrid (Spain)); Martinez Ruis, F.; Manuzi, M.A. (Dpto. de Traumatologia Centro Ramon y Cajal, Madrid (Spain))

    1984-01-01

    An introduction to the cortical bone neutron irradiation subject and to the effect of the irradiation on the mechanical properties of bone considered as a composite material is presented. Only the special case of the simple flexion has been treated. The evolution of the load-deflection curve as a function of the epithermal neutron dose has been studied. Some hypotheses on the role performed by the organic and mineral phases are introduced.

  4. INFLUENCE OF SCATTERED NEUTRON RADIATION ON METROLOGICAL CHARACTERISTICS OF АТ140 NEUTRON CALIBRATION FACILITY

    Directory of Open Access Journals (Sweden)

    D. I. Komar

    2017-01-01

    Full Text Available Today facilities with collimated radiation field are widely used as reference in metrological support of devices for neutron radiation measurement. Neutron fields formed by radionuclide neutron sources. The aim of this research was to study characteristics of experimentally realized neutron fields geometries on АТ140 Neutron Calibration Facility using Monte Carlo method.For calibration, we put a device into neutron field with known flux density or ambient equivalent dose rate. We can form neutron beam from radionuclide fast-neutron source in different geometries. In containercollimator of АТ140 Neutron Calibration Facility we can install special inserts to gather fast-neutron geometry or thermal-neutron geometry. We need to consider neutron scattering from air and room’s walls. We can conduct measurements of neutron field characteristics in several points and get the other using Monte Carlo method.Thermal neutron collimator forms a beam from radionuclide source with a significant amount of neutrons with thermal energies. From found relationship between full neutron flux and distance to neutron source we see that inverse square law is violated. Scattered radiation contribution into total flux increases when we are moving away from neutron source and significantly influences neutron fields characteristics. While source is exposed in shadow-cone geometry neutron specter has pronounced thermal component from wall scattering.In this work, we examined main geometry types used to acquire reference neutron radiation using radionuclide sources. We developed Monte Carlo model for 238Pu-Be neutron source and АТ140 Neutron Calibration Facility’s container-collimator. We have shown the most significant neutron energy distribution factor to be scattered radiation from room’s walls. It leads to significant changes of neutron radiation specter at a distance from the source. When planning location, and installing the facility we should consider

  5. SUGGEL: A Program Suggesting the Orbital Angular Momentum of a Neutron Resonance from the Magnitude of its Neutron Width

    Energy Technology Data Exchange (ETDEWEB)

    Oh, S.Y.

    2001-02-02

    The SUGGEL computer code has been developed to suggest a value for the orbital angular momentum of a neutron resonance that is consistent with the magnitude of its neutron width. The suggestion is based on the probability that a resonance having a certain value of g{Gamma}{sub n} is an l-wave resonance. The probability is calculated by using Bayes' theorem on the conditional probability. The probability density functions (pdf's) of g{Gamma}{sub n} for up to d-wave (l=2) have been derived from the {chi}{sup 2} distribution of Porter and Thomas. The pdf's take two possible channel spins into account. This code is a tool which evaluators will use to construct resonance parameters and help to assign resonance spin. The use of this tool is expected to reduce time and effort in the evaluation procedure, since the number of repeated runs of the fitting code (e.g., SAMMY) may be reduced.

  6. Reduced neutron widths in the nuclear data ensemble: Experiment andtheory do not agree

    Directory of Open Access Journals (Sweden)

    Koehler P.E.

    2010-03-01

    Full Text Available I have analyzed reduced neutron widths (Γ0n for the subset of 1245 resonances in the nuclear data ensemble (NDE for which they have been reported. Random matrix theory (RMT predicts for the Gaussian orthogonal ensemble (GOE that these widths should follow a χ2 distribution having one degree of freedom (ν = 1 - the Porter Thomas (PT distribution. Using the maximum-likelihood (ML technique, I have determined that the Γ0n values in the NDE are best described by a χ2 distribution having ν = 0.80 ± 0.052, which is 3.8 standard deviations smaller than predicted by RMT. I show that this striking disagreement is most likely due to the inclusion of significant p-wave contamination to the supposedly pure s-wave NDE. Furthermore, when an energy-dependent threshold is used to remove the p-wave contamination, ML analysis yields ν = 1.217 ± 0.092 for the remaining data, still in poor agreement with the RMT prediction for the GOE. These results cast very serious doubt on claims that the NDE represents a striking confirmation of RMT.

  7. Radiation Fields in the Vicinity of Compact Accelerator Neutron Generators

    Energy Technology Data Exchange (ETDEWEB)

    David L. Chichester; Brandon W. Blackburn; Augustine J. Caffrey

    2006-10-01

    Intense pulsed radiation fields emitted from sealed tube neutron generators provide a challenge for modern health physics survey instrumentation. The spectral sensitivity of these survey instruments requires calibration under realistic field conditions while the pulsed emission characteristics of neutron generators can vary from conditions of steady-state operation. As a general guide for assessing radiological conditions around neutron generators, experiments and modeling simulations have been performed to assess radiation fields near DD and DT neutron generators. The presence of other materials and material configurations can also have important effects on the radiation dose fields around compact accelerator neutron generators.

  8. Reconciling Coulomb breakup and neutron radiative capture

    Science.gov (United States)

    Capel, P.; Nollet, Y.

    2017-07-01

    The Coulomb-breakup method to extract the cross section for neutron radiative capture at astrophysical energies is analyzed in detail. In particular, its sensitivity to the description of the neutron-core continuum is ascertained. We consider the case of 14C(n ,γ )15C for which both the radiative capture at low energy and the Coulomb breakup of 15C into 14C+n on Pb at 68 MeV/nucleon have been measured with accuracy. We confirm the direct proportionality of the cross section for both reactions to the square of the asymptotic normalization constant of 15C observed by Summers and Nunes [Phys. Rev. C 78, 011601(R) (2008), 10.1103/PhysRevC.78.011601], but we also show that the 14C-n continuum plays a significant role in the calculations. Fortunately, the method proposed by Summers and Nunes can be improved to absorb that continuum dependence. We show that a more precise radiative-capture cross section can be extracted selecting the breakup data at forward angles and low 14C-n relative energies.

  9. Neutron dosimetry and radiation damage calculations for HFBR

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, L.R.; Ratner, R.T. [Pacific Northwest National Lab., TN (United States)

    1998-03-01

    Neutron dosimetry measurements have been conducted for various positions of the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) in order to measure the neutron flux and energy spectra. Neutron dosimetry results and radiation damage calculations are presented for positions V10, V14, and V15.

  10. Reusable shielding material for neutron- and gamma-radiation

    Science.gov (United States)

    Calzada, Elbio; Grünauer, Florian; Schillinger, Burkhard; Türck, Harald

    2011-09-01

    At neutron research facilities all around the world radiation shieldings are applied to reduce the background of neutron and gamma radiation as far as possible in order to perform high quality measurements and to fulfill the radiation protection requirements. The current approach with cement-based compounds has a number of shortcomings: "Heavy concrete" contains a high amount of elements, which are not desired to obtain a high attenuation of neutron and/or gamma radiation (e.g. calcium, carbon, oxygen, silicon and aluminum). A shielding material with a high density of desired nuclei such as iron, hydrogen and boron was developed for the redesign of the neutron radiography facility ANTARES at beam tube 4 (located at a cold neutron source) of FRM-II. The composition of the material was optimized by help of the Monte Carlo code MCNP5. With this shielding material a considerable higher attenuation of background radiation can be obtained compared to usual heavy concretes.

  11. Nuclear Targets for a Precision Measurement of the Neutral Pion Radiative Width

    Energy Technology Data Exchange (ETDEWEB)

    Martel, Philippe; Clinton, Eric; McWilliams, R.; Lawrence, Dave; Miskimen, Rory; Ahmidouch, Abdellah; Ambrozewicz, Pawel; Asaturyan, Arshak; Baker, O.; Benton, LaRay; Bernstein, Aron; Cole, Philip; Collins, Patrick; Dale, Daniel; Danagoulian, Samuel; Davidenko, G.; Demirchyan, Raphael; Deur, Alexandre; DOLGOLENKO, A.; Dzyubenko, Georgiy; Evdokimov, Anatoly; Feng, JIng; Gabrielyan, Marianna; Gan, Liping; Gasparian, Ashot; Glamazdin, Oleksandr; Goryachev, Vladimir; Gyurjyan, Vardan; Hardy, K.; Ito, Mark; Khandaker, Mahbubul; Kingsberry, Paul; Kolarkar, Ameya; Konchatnyi, Mykhailo; Korchin, O.; Korsch, Wolfgang; Kowalski, Stanley; Kubantsev, Mikhail; Kubarovsky, Valery; LARIN, Ilya; MATVEEV, V.; McNulty, Dustin; Milbrath, Brian; Minehart, Ralph; Mochalov, Vasiliy; Mtingwa, Sekazi; Nakagawa, Itaru; Overby, Steven; Pasyuk, Evgueni; Payen, Marvin; Pedroni, Ronald; Prok, Yelena; Ritchie, Barry; Salgado, Carlos; Sitnikov, Anatoly; Sober, Daniel; Stephens, W.; Teymurazyan, Aram; Underwood, Jarreas; VASILIEV, A.; VEREBRYUSOV, V.; Vishnyakov, Vladimir; Wood, Michael

    2009-12-01

    A technique is presented for precision measurements of the area densities, density * T, of approximately 5% radiation length carbon and 208Pb targets used in an experiment at Jefferson Laboratory to measure the neutral pion radiative width. The precision obtained in the area density for the carbon target is +/- 0.050%, and that obtained for the lead target through an x-ray attenuation technique is +/- 0.43%.

  12. Study on neutron radiation field of carbon ions therapy

    CERN Document Server

    Xu, Jun-Kui; Li, Wu-Yuan; Yan, Wei-Wei; Chen, Xi-Meng; Mao, Wang; Pang, Cheng-Guo

    2015-01-01

    Carbon ions offer significant advantages for deep-seated local tumors therapy due to their physical and biological properties. Secondary particles, especially neutrons caused by heavy ion reactions should be carefully considered in treatment process and radiation protection. For radiation protection purposes, the FLUKA Code was used in order to evaluate the radiation field at deep tumor therapy room of HIRFL in this paper. The neutron energy spectra, neutron dose and energy deposition of carbon ion and neutron in tissue-like media was studied for bombardment of solid water target by 430MeV/u C ions. It is found that the calculated neutron dose have a good agreement with the experimental date, and the secondary neutron dose may not exceed one in a thousand of the carbon ions dose at Bragg peak area in tissue-like media.

  13. Development of advanced radiation monitors for pulsed neutron fields

    CERN Document Server

    AUTHOR|(CDS)2081895

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

  14. Finite width of the sonic event horizon and grey body Hawking radiation

    CERN Document Server

    Vinish, Y

    2014-01-01

    Finite width of the analog event horizon is determined by the nonlinearity length in the Kerr nonlinear optical system, which is discussed here, or by the healing length in Bose-Einstein condensates. The various eigen modes of fluctuations are found in the immediate vicinity of the event horizon and the scattering matrix due to the finite width horizon is calculated to within the leading order correction in the nonlinearity length. The Hawking radiation is found to be that of a grey body with the emissivity larger than one. A procedure of paraxial quantization of the fluctuation field is discussed and its connection to the conventional quantization of the electromagnetic field is demonstrated.

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

    Directory of Open Access Journals (Sweden)

    Zhou Dong

    2015-09-01

    Full Text Available Background. Penumbra characteristics play a significant role in dose delivery accuracy for radiation therapy. For treatment planning, penumbra width and radiation field offset strongly influence target dose conformity and organ at risk sparing.

  16. Measurement of accelerator neutron radiation field spectrum by Extended Range Neutron Multisphere Spectrometers and unfolding program

    CERN Document Server

    Li, Guanjia; Ma, Zhongjian; Guo, Siming; Yan, Mingyang; Shi, Haoyu; Xu, Chao

    2015-01-01

    This paper described a measurement of accelerator neutron radiation field at a transport beam line of Beijing-TBF. The experiment place was be selected around a Faraday Cup with a graphite target impacted by electron beam at 2.5GeV. First of all, we simulated the neutron radiation experiment by FLUKA. Secondly, we chose six appropriate ERNMS according to their neutron fluence response function to measure the neutron count rate. Then the U_M_G package program was be utilized to unfolding experiment data. Finally, we drew a comparison between the unfolding with the simulation spectrum and made an analysis about the result.

  17. Low cost CCD camera protection against neutron radiation damage.

    Science.gov (United States)

    Kok, J G M

    2005-01-01

    At a radiotherapy department cancer patients are treated with high energy electron and photon beams. These beams are produced by a linear accelerator. A closed circuit television system is used to monitor patients during treatment. Although CCD cameras are rather resistant to stray radiation, they are damaged by the low flux of neutrons which are produced by the linac as a side effect. PVC can be used to reduce damage to CCD cameras induced by neutron radiation. A box with 6 cm thick walls will extend the life of the camera at least by a factor of two. A PVC neutron shield is inexpensive. PVC is easy to obtain and the box is simple to construct. A similar box made out of PE will not reduce neutron damage to a CCD camera. Although PE is a good medium to moderate faster neutrons, thereby reducing some of the bulk defects, it will not capture thermal neutrons which induce surface damage.

  18. Radiation fields from neutron generators shielded with different materials

    Science.gov (United States)

    Chichester, D. L.; Blackburn, B. W.

    2007-08-01

    As a general guide for assessing radiological conditions around a DT neutron generator numerical modeling has been performed to assess neutron and photon dose profiles for a variety of shield materials ranging from 1 to 100 cm thick. In agreement with accepted radiation safety practices high-Z materials such as bismuth and lead have been found to be ineffective biological shield materials, owing in part to the existence of (n,2n) reaction channels available with 14.1 MeV DT neutrons, while low-Z materials serve as effective shields for these sources. Composite materials such as a mixture of polyethylene and bismuth, or regular concrete, are ideal shield materials for neutron generator radiation because of their ability to attenuate internally generated photon radiation resulting from neutron scattering and capture within the shields themselves.

  19. Direct radiative capture of p-wave neutrons

    CERN Document Server

    Mengoni, A; Ishihara, M

    1995-01-01

    The neutron direct radiative capture (DRC) process is investigated, highlighting the role of incident p-wave neutrons. A set of calculations is shown for the 12-C(n,gamma) process at incoming neutron energies up to 500 keV, a crucial region for astrophysics. The cross section for neutron capture leading to loosely bound s, p and d orbits of 13-C is well reproduced by the DRC model demonstrating the feasibility of using this reaction channel to study the properties of nuclear wave functions on and outside the nuclear surface. A sensitivity analysis of the results on the neutron-nucleus interaction is performed for incident s- as well as p-waves. It turned out that the DRC cross section for p-wave neutrons is insensitive to this interaction, contrary to the case of incident s-wave neutrons. PACS number(s): 25.40Lw,21.10Gv,23.40.Hc

  20. Research of Fast Neutron Radiation Effect on Rats

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In order to research the fast neutron radiation effect on rats,the 8 weeks Wistar male rats were wholly irradiated by 14 MeV fast neutron with 5 Gy. In the experiment,the rats were divided into normal and irradiation group, and killed

  1. Measurement of the radiative decay width \\Gamma[\\Lambda(1520) --> \\Lambda \\gamma] with the SPHINX spectrometer

    CERN Document Server

    Antipov, Y M; Batarin, V A; Vavilov, D V; Victorov, V A; Eroshin, O V; Golovkin, S V; Gorin, Yu P; Kolganov, V Z; Kozhevnikov, A P; Konstantinov, A S; Kubarovskii, V P; Kurshetsov, V F; Landsberg, L G; Leontiev, V M; Lomkatsi, G S; Molchanov, V V; Mukhin, V A; Nilov, A F; Patalakha, D I; Petrenko, S V; Smolyankin, V T; Antipov, Yu.M.; Gorin, Yu.P.

    2004-01-01

    The radiative decay \\Lambda(1520) --> \\Lambda \\gamma was measured directly in the study of exclusive diffractive-like reaction p + N --> \\Lambda(1520) K^+ + N, \\Lambda(1520) --> \\Lambda \\gamma with the SPHINX spectrometer. The values of the branching and partial width of this radiative decay were obtained: BR[\\Lambda(1520) --> \\Lambda \\gamma] = (1.02+/-0.21)x10^{-2} and \\Gamma[\\Lambda(1520) \\to \\Lambda \\gamma] = 159+/-35 keV (statistical uncertainty). The systematic uncertainty is estimated to be below 15%.

  2. Status of radiation detector and neutron monitor technology

    CERN Document Server

    Kim, Y K; Ha, J H; Han, S H; Hong, S B; Hwang, I K; Lee, W G; Moon, B S; Park, S H; Song, M H

    2002-01-01

    In this report, we describe the current states of the radiation detection technology, detectors for industrial application, and neutron monitors. We also survey the new technologies being applied to this field. The method to detect radiation is the measurement of the observable secondary effect from the interaction between incident radiation and detector material, such as ionization, excitation, fluorescence, and chemical reaction. The radiation detectors can be categorized into gas detectors, scintillation detectors, and semiconductor detectors according to major effects and main applications. This report contains the current status and operational principles of these detectors. The application fields of radiation detectors are industrial measurement system, in-core neutron monitor, medical radiation diagnostic device, nondestructive inspection device, environmental radiation monitoring, cosmic-ray measurement, security system, fundamental science experiment, and radiation measurement standardization. The st...

  3. Monte Carlo Calculations for Neutron and Gamma Radiation Fields on a Fast Neutron Irradiation Device

    Science.gov (United States)

    Vieira, A.; Ramalho, A.; Gonçalves, I. C.; Fernandes, A.; Barradas, N.; Marques, J. G.; Prata, J.; Chaussy, Ch.

    We used the Monte Carlo program MCNP to calculate the neutron and gamma fluxes on a fast neutron irradiation facility being installed on the Portuguese Research Reactor (RPI). The purpose of this facility is to provide a fast neutron beam for irradiation of electronic circuits. The gamma dose should be minimized. This is achieved by placing a lead shield preceded by a thin layer of boral. A fast neutron flux of the order of 109 n/cm2s is expected at the exit of the tube, while the gamma radiation is kept below 20 Gy/h. We will present results of the neutron and gamma doses for several locations along the tube and different thickness of the lead shield. We found that the neutron beam is very collimated at the end of the tube with a dominant component on the fast region.

  4. Study of Neutron and Gamma Radiation Protective Shield

    OpenAIRE

    Eskandar Asadi Amirabadi; Marzieh Salimi; Nima Ghal-Eh; Gholam Reza Etaati; Hossien Asadi

    2013-01-01

    Due to the development of nuclear technology and use of these technologies in various fields of industry, medicine, research and etc, protection against radioactive rays is one of the most important topics in this field .The purpose of this is to reduce the dose rate from radioactive sources. The sources in terms of components are emitted various types of nuclear radiation with different energies. These radiations are involving of alpha particles, beta, and neutron and gamma radiation. Given ...

  5. GEM detectors development for radiation environment: neutron tests and simulations

    Science.gov (United States)

    Chernyshova, Maryna; Jednoróg, Sławomir; Malinowski, Karol; Czarski, Tomasz; Ziółkowski, Adam; Bieńkowska, Barbara; Prokopowicz, Rafał; Łaszyńska, Ewa; Kowalska-Strzeciwilk, Ewa; Poźniak, Krzysztof T.; Kasprowicz, Grzegorz; Zabołotny, Wojciech; Wojeński, Andrzej; Krawczyk, Rafał D.; Linczuk, Paweł; Potrykus, Paweł; Bajdel, Barcel

    2016-09-01

    One of the requests from the ongoing ITER-Like Wall Project is to have diagnostics for Soft X-Ray (SXR) monitoring in tokamak. Such diagnostics should be focused on tungsten emission measurements, as an increased attention is currently paid to tungsten due to a fact that it became a main candidate for the plasma facing material in ITER and future fusion reactor. In addition, such diagnostics should be able to withstand harsh radiation environment at tokamak during its operation. The presented work is related to the development of such diagnostics based on Gas Electron Multiplier (GEM) technology. More specifically, an influence of neutron radiation on performance of the GEM detectors is studied both experimentally and through computer simulations. The neutron induced radioactivity (after neutron source exposure) was found to be not pronounced comparing to an impact of other secondary neutron reaction products (during the exposure).

  6. Characterization of the radiation background at the Spallation Neutron Source

    Science.gov (United States)

    DiJulio, Douglas D.; Cherkashyna, Nataliia; Scherzinger, Julius; Khaplanov, Anton; Pfeiffer, Dorothea; Cooper-Jensen, Carsten P.; Fissum, Kevin G.; Kanaki, Kalliopi; Kirstein, Oliver; Ehlers, Georg; Gallmeier, Franz X.; Hornbach, Donald E.; Iverson, Erik B.; Newby, Robert J.; Hall-Wilton, Richard J.; Bentley, Phillip M.

    2016-09-01

    We present a survey of the radiation background at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, TN, USA during routine daily operation. A broad range of detectors was used to characterize primarily the neutron and photon fields throughout the facility. These include a WENDI-2 extended range dosimeter, a thermoscientific NRD, an Arktis 4He detector, and a standard NaI photon detector. The information gathered from the detectors was used to map out the neutron dose rates throughout the facility and also the neutron dose rate and flux profiles of several different beamlines. The survey provides detailed information useful for developing future shielding concepts at spallation neutron sources, such as the European Spallation Source (ESS), currently under construction in Lund, Sweden.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-11

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

  8. Radiation Damages in Aluminum Alloy SAV-1 under Neutron Irradiation

    Science.gov (United States)

    Salikhbaev, Umar; Akhmedzhanov, Farkhad; Alikulov, Sherali; Baytelesov, Sapar; Boltabaev, Azizbek

    2016-05-01

    The aim of this work was to study the effect of neutron irradiation on the kinetics of radiation damages in the SAV-1 alloy, which belongs to the group of aluminum alloys of the ternary system Al-Mg-Si. For fast-neutron irradiation by different doses up to fluence 1019 cm-2 the SAV-1 samples were placed in one of the vertical channels of the research WWR type reactor (Tashkent). The temperature dependence of the electrical resistance of the alloy samples was investigated in the range 290 - 490 K by the four-compensation method with an error about 0.1%. The experimental results were shown that at all the temperatures the dependence of the SAV-1 alloy resistivity on neutron fluence was nonlinear. With increasing neutron fluence the deviation from linearity and the growth rate of resistivity with temperature becomes more appreciable. The observed dependences are explained by means of martensitic transformations and the radiation damages in the studied alloy under neutron irradiation. The mechanisms of radiation modification of the SAV-1 alloy structure are discussed.

  9. Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress

    Science.gov (United States)

    Schooneveld, E. M.; Pietropaolo, A.; Andreani, C.; Perelli Cippo, E.; Rhodes, N. J.; Senesi, R.; Tardocchi, M.; Gorini, G.

    2016-09-01

    Neutron scattering techniques are attracting an increasing interest from scientists in various research fields, ranging from physics and chemistry to biology and archaeometry. The success of these neutron scattering applications is stimulated by the development of higher performance instrumentation. The development of new techniques and concepts, including radiative capture based neutron detection, is therefore a key issue to be addressed. Radiative capture based neutron detectors utilize the emission of prompt gamma rays after neutron absorption in a suitable isotope and the detection of those gammas by a photon counter. They can be used as simple counters in the thermal region and (simultaneously) as energy selector and counters for neutrons in the eV energy region. Several years of extensive development have made eV neutron spectrometers operating in the so-called resonance detector spectrometer (RDS) configuration outperform their conventional counterparts. In fact, the VESUVIO spectrometer, a flagship instrument at ISIS serving a continuous user programme for eV inelastic neutron spectroscopy measurements, is operating in the RDS configuration since 2007. In this review, we discuss the physical mechanism underlying the RDS configuration and the development of associated instrumentation. A few successful neutron scattering experiments that utilize the radiative capture counting techniques will be presented together with the potential of this technique for thermal neutron diffraction measurements. We also outline possible improvements and future perspectives for radiative capture based neutron detectors in neutron scattering application at pulsed neutron sources.

  10. Neutron radiation effect on carbon-loaded polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Ervedosa, Eduardo P.; Santos, Luiz A.P., E-mail: lasantos@cnen.gov.br, E-mail: eduardoervedosa@hotmail.com [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Genezini, Frederico A., E-mail: fredzini@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    This work aims to study the changes in the electrical conductivity of carbon-loaded polyethylene after neutron irradiation. The material is a polymer-based semiconductor and it was used to evaluate the neutron flux in a research nuclear reactor. The main advantage with this type of semiconductor concerns about that the composite itself is not a material that bring high neutron activation. Such a feature could allow for measuring the neutron flux in real time with the advantage that it is a low cost material. Samples in triplicate with identical geometries were prepared and irradiated at different time intervals in order to evaluate the material response to neutron radiation in function of its electrical property. The method of measurement is based on the voltage yielded when a high precision ultra-low constant current is passing through the material. The results show that if this polymer based semiconductor is submitted to a neutron flux from a nuclear reactor it presents a systematic variation in its electrical resistance and one can conclude that this material can be used as a neutron sensor. (author)

  11. Optimal width of quasicrystalline slabs of dielectric cylinders to microwave radiation transmission contrast

    Science.gov (United States)

    Andueza, Ángel; Wang, Kang; Pérez-Conde, Jesús; Sevilla, Joaquín

    2016-08-01

    Light confinement induced by resonant states in aperiodic photonic structures is interesting for many applications. A particular case of these resonances can be found in 2D quasicrystalline arrangements of dielectric cylinders. These systems present a rather isotropic band gap as well as isolated in-gap photonic states (as a result of spatially localized resonances). These states are built by high symmetry polygonal clusters that can be regarded as photonic molecules. In this paper, we study the transmission properties of a slab of glass cylinders arranged in approximants of the decagonal quasicrystalline structure. In particular, we investigate the influence of the slab width in the transmission contrast between the states and the gap. The study is both experimental and numerical in the microwave regime. We find that the best transmission contrast is found for a width of around three times the radiation wavelength. The transmission in the band gap region is mediated by the resonances of the photonic molecules. If the samples are thin enough, they become transparent except around a resonance of the photonic molecule which reflects the incoming light.

  12. HSC5: synchrotron radiation and neutrons for cultural heritage studies

    Energy Technology Data Exchange (ETDEWEB)

    Michel, Anne [Institut Neel - CNRS, 38 - Grenoble (France); Artioli, G. [Padova Univ. (Italy); Bleuet, P.; Cotte, M.; Tafforeau, P.; Susini, J. [European Synchrotron Radiation Facility, 38 - Grenoble (France); Dumas, P.; Somogyl, A. [SOLEIL Synchrotron, 91 - Gif sur Yvette (France); Cotte, M. [Centre de Recherche et de Restauration des Musees de France, UMR171, 75 - Paris (France)]|[European Synchrotron Radiation Facility, 38 - Grenoble (France); Kockelmann, W. [Science and Technology Facilities Council, Rutherford Appleton Lab. (United Kingdom); Kolar, J. [Ljubljana Univ., Morana RTD, Slovenia, Faculty of Chemistry and Chemical Technology (Slovenia); Areon, I. [Nova Gorica Univ. (Slovenia); Meden, A.; Strlie, M. [Ljubljana Univ., Faculty of Chemistry and Chemical Technology (Slovenia); Pantos, M. [Daresbury Laboratory, Warrington (United Kingdom); Vendrell, M. [Barcelona Univ., dept. of Crystallography and Mineralogy (Spain); Wess, T. [Cardiff Univ., School of Optometry and Institute of Vision (Ireland); Gunneweg, J. [Hebrew Univ., Jerusalem (Israel)

    2007-07-01

    Synchrotron and neutron sources offer recent and additional insight into the records of our cultural past. Over the last years, there has been an increasing demand for access to synchrotron radiation- and neutron-based techniques, and their applications in the fields of archaeological science and cultural heritage. The purpose of this Hercules Specialized Course is to give the participants an introduction to the basic principles of synchrotron radiation and neutron techniques (imaging, microscopy, diffraction, absorption and fluorescence, IR spectroscopy). The school provides cross-disciplinary examples illustrating the abilities of these techniques in a representative range of scientific cases concerning painting, archaeological artefacts, inks, pigments, fossils and the Dead Sea scrolls. This document gathers only the resumes of the lectures.

  13. Moessbauer studies of hemoglobin in erythrocytes exposed to neutron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Niemiec, Katarzyna; Kaczmarska, Magdalena; Buczkowski, Mateusz [AGH University, Faculty of Physics and Computer Science, Department of Medical Physics and Biophysics (Poland); Fornal, Maria [Collegium Medicum, Jagiellonian University, Department of Internal Medicine and Gerontology (Poland); Pohorecki, Wladyslaw [AGH University, Faculty of Energy and Fuels (Poland); Matlak, Krzysztof; Korecki, Jozef [AGH University, Faculty of Physics and Computer Science, Department of Solid State Physics (Poland); Grodzicki, Tomasz [Collegium Medicum, Jagiellonian University, Department of Internal Medicine and Gerontology (Poland); Burda, Kvetoslava, E-mail: kvetoslava.burda@fis.agh.edu.pl [AGH University, Faculty of Physics and Computer Science, Department of Medical Physics and Biophysics (Poland)

    2012-03-15

    We studied radiation effects on the stability of various states of hemoglobin (Hb) in red blood cells (RBC) irradiated with a very low dose of neutron rays, 50 {mu}Gy. We investigated RBCs isolated from blood of healthy donors. Moessbauer spectroscopy was applied to monitor different forms of Hb. Our results show, for the first time, that oxyhemoglobin (OxyHb) and deoxyhemoglobin (DeoxyHb) are two Hb forms sensitive to such a low neutron radiation. Both Hbs change into a new Hb form (Hb{sub irr}). Additionally, OxyHb transfers into HbOH/H{sub 2}O, which under our experimental conditions is resistant to the action of neutron rays.

  14. Thermal radiation from magnetic neutron star surfaces

    CERN Document Server

    Pérez-Azorin, J F; Pons, J A

    2005-01-01

    We investigate the thermal emission from magnetic neutron star surfaces in which the cohesive effects of the magnetic field have produced the condensation of the atmosphere and the external layers. This may happen for sufficiently cool atmospheres with moderately intense magnetic fields. The thermal emission from an isothermal bare surface of a neutron star shows no remarkable spectral features, but it is significantly depressed at energies below some threshold energy. However, since the thermal conductivity is very different in the normal and parallel directions to the magnetic field lines, the presence of the magnetic field is expected to produce a highly anisotropic temperature distribution, depending on the magnetic field geometry. In this case, the observed flux of such an object looks very similar to a BB spectrum, but depressed in a nearly constant factor at all energies. This results in a systematic underestimation of the area of the emitter (and therefore its size) by a factor 5-10 (2-3).

  15. Radiative neutron capture: Hauser Feshbach vs. statistical resonances

    Science.gov (United States)

    Rochman, D.; Goriely, S.; Koning, A. J.; Ferroukhi, H.

    2017-01-01

    The radiative neutron capture rates for isotopes of astrophysical interest are commonly calculated on the basis of the statistical Hauser Feshbach (HF) reaction model, leading to smooth and monotonically varying temperature-dependent Maxwellian-averaged cross sections (MACS). The HF approximation is known to be valid if the number of resonances in the compound system is relatively high. However, such a condition is hardly fulfilled for keV neutrons captured on light or exotic neutron-rich nuclei. For this reason, a different procedure is proposed here, based on the generation of statistical resonances. This novel technique, called the "High Fidelity Resonance" (HFR) method is shown to provide similar results as the HF approach for nuclei with a high level density but to deviate and be more realistic than HF predictions for light and neutron-rich nuclei or at relatively low sub-keV energies. The MACS derived with the HFR method are systematically compared with the traditional HF calculations for some 3300 neutron-rich nuclei and shown to give rise to significantly larger predictions with respect to the HF approach at energies of astrophysical relevance. For this reason, the HF approach should not be applied to light or neutron-rich nuclei. The Doppler broadening of the generated resonances is also studied and found to have a negligible impact on the calculated MACS.

  16. Radiative neutron capture: Hauser Feshbach vs. statistical resonances

    Directory of Open Access Journals (Sweden)

    D. Rochman

    2017-01-01

    Full Text Available The radiative neutron capture rates for isotopes of astrophysical interest are commonly calculated on the basis of the statistical Hauser Feshbach (HF reaction model, leading to smooth and monotonically varying temperature-dependent Maxwellian-averaged cross sections (MACS. The HF approximation is known to be valid if the number of resonances in the compound system is relatively high. However, such a condition is hardly fulfilled for keV neutrons captured on light or exotic neutron-rich nuclei. For this reason, a different procedure is proposed here, based on the generation of statistical resonances. This novel technique, called the “High Fidelity Resonance” (HFR method is shown to provide similar results as the HF approach for nuclei with a high level density but to deviate and be more realistic than HF predictions for light and neutron-rich nuclei or at relatively low sub-keV energies. The MACS derived with the HFR method are systematically compared with the traditional HF calculations for some 3300 neutron-rich nuclei and shown to give rise to significantly larger predictions with respect to the HF approach at energies of astrophysical relevance. For this reason, the HF approach should not be applied to light or neutron-rich nuclei. The Doppler broadening of the generated resonances is also studied and found to have a negligible impact on the calculated MACS.

  17. RADIATION PERFORMANCE OF GAN AND INAS/GAAS QUANTUM DOT BASED DEVICES SUBJECTED TO NEUTRON RADIATION

    Directory of Open Access Journals (Sweden)

    Dhiyauddin Ahmad Fauzi

    2017-05-01

    Full Text Available In addition to their useful optoelectronics functions, gallium nitride (GaN and quantum dots (QDs based structures are also known for their radiation hardness properties. With demands on such semiconductor material structures, it is important to investigate the differences in reliability and radiation hardness properties of these two devices. For this purpose, three sets of GaN light-emitting diode (LED and InAs/GaAs dot-in-a well (DWELL samples were irradiated with thermal neutron of fluence ranging from 3×1013 to 6×1014 neutron/cm2 in PUSPATI TRIGA research reactor. The radiation performances for each device were evaluated based on the current-voltage (I-V and capacitance-voltage (C-V electrical characterisation method. Results suggested that the GaN based sample is less susceptible to electrical changes due to the thermal neutron radiation effects compared to the QD based sample.

  18. Measurement of radiative widths of $a_2(1320)$ and $\\pi_2(1670)$

    CERN Document Server

    Adolph, C; Alekseev, M G; Alexeev, G D; Amoroso, A; Andrieux, V; Anosov, V; Austregesilo, A; Badelek, B; Balestra, F; Barth, J; Baum, G; Beck, R; Bedfer, Y; Berlin, A; Bernhard, J; Bicker, K; Bieling, J; Birsa, R; Bisplinghoff, J; Bodlak, M; Boer, M; Bordalo, P; Bradamante, F; Braun, C; Bressan, A; Buchele, M; Burtin, E; Capozza, L; Chiosso, M; Chung, S U; Cicuttin, A; Crespo, M L; Curiel, Q; Dalla Torre, S; Dasgupta, S S; Dasgupta, S; Denisov, O Yu; Donskov, S V; Doshita, N; Duic, V; Dunnweber, W; Dziewiecki, M; Efremov, A; Elia, C; Eversheim, P D; Eyrich, W; Faessler, M; Ferrero, A; Filin, A; Finger, M; Finger jr, M; Fischer, H; Franco, C; du Fresne von Hohenesche, N; Friedrich, J.M; Frolov, V; Gautheron, F; Gavrichtchouk, O P; Gerassimov, S; Geyer, R; Gnesi, I; Gobbo, B; Goertz, S; Gorzellik, M; Grabmuller, S; Grasso, A; Grube, B; Guskov, A; Guthorl, T; Haas, F; von Harrach, D; Hahne, D; Hashimoto, R; Heinsius, F H; Herrmann, F; Hinterberger, F; Hoppner, Ch; Horikawa, N; d'Hose, N; Huber, S; Ishimoto, S; Ivanov, A; Ivanshin, Yu; Iwata, T; Jahn, R; Jary, V; Jasinski, P; Jorg, P; Joosten, R; Kabuss, E; Ketzer, B; Khaustov, G V; Khokhlov, Yu A; Kisselev, Yu; Klein, F; Klimaszewski, K; Koivuniemi, J H; Kolosov, V N; Kondo, K; Konigsmann, K; Konorov, I; Konstantinov, V F; Kotzinian, A M; Kouznetsov, O; Kral, Z; Kramer, M; Kroumchtein, Z V; Kuchinski, N; Kunne, F; Kurek, K; Kurjata, R P; Lednev, A.A; Lehmann, A; Levorato, S; Lichtenstadt, J; Maggiora, A; Magnon, A; Makke, N; Mallot, G K; Marchand, C; Martin, A; Marzec, J; Matousek, J; Matsuda, H; Matsuda, T; Meshcheryakov, G; Meyer, W; Michigami, T; Mikhailov, Yu V; Miyachi, Y; Nagaytsev, A; Nagel, T; Nerling, F; Neubert, S; Neyret, D; Nikolaenko, V I; Novy, J; Nowak, W D; Nunes, A S; Orlov, I; Olshevsky, A G; Ostrick, M; Panknin, R; Panzieri, D; Parsamyan, B; Paul, S; Pesek, M; Platchkov, S; Pochodzalla, J; Polyakov, V A; Pretz, J; Quaresma, M; Quintans, C; Ramos, S; Reicherz, G; Rocco, E; Rychter, A; Rossiyskaya, N S; Ryabchikov, D I; Samoylenko, V D; Sandacz, A; Sarkar, S; Savin, I A; Sbrizzai, G; Schiavon, P; Schill, C; Schluter, T; Schmidt, A; Schmidt, K; Schmieden, H; Schonning, K; Schopferer, S; Schott, M; Shevchenko, O Yu; Silva, L; Sinha, L; Sirtl, S; Slunecka, M; Sosio, S; Sozzi, F; Srnka, A; Steiger, L; Stolarski, M; Sulc, M; Sulej, R; Suzuki, H; Szabelski, A; Szameitat, T; Sznajder, P; Takekawa, S; ter Wolbeek, J; Tessaro, S; Tessarotto, F; Thibaud, F; Uhl, S; Uman, I; Vandenbroucke, M; Virius, M; Vondra, J; Wang, L; Weisrock, T; Wilfert, M; Windmolders, R; Wollny, H; Zaremba, K; Zavertyaev, M; Zemlyanichkina, E; Ziembicki, M

    2014-01-01

    The COMPASS Collaboration at CERN has investigated the reaction $\\pi^- \\gamma \\rightarrow \\pi^-\\pi^-\\pi^+$ embedded in the Primakoff reaction of $190~\\textrm{GeV}$ pions scattering in the Coulomb field of a lead target, $\\pi^- \\text{Pb} \\rightarrow \\pi^-\\pi^-\\pi^+ \\text{Pb}$. Exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at momentum transfer below $0.001~(\\text{GeV}/c)^2$. Using a partial-wave analysis the amplitudes and relative phases of the $a_2(1320)$ and $\\pi_2(1670)$ mesons have been extracted, and the Coulomb and the diffractive contributions have been disentangled. Measuring absolute production cross sections we have determined the radiative width of the $a_2(1320)$ to be $\\Gamma_0(a_2(1320) \\rightarrow \\pi\\gamma) = (358 \\pm 6_{\\textrm{stat}} \\pm 42_{\\textrm{syst}})~\\textrm{keV}$. As the first measurement, $\\Gamma_0(\\pi_2(1670) \\rightarrow \\pi\\gamma) = (181 \\pm 11_{\\textrm{stat}} \\pm 27_{\\textrm{syst}})~\\textrm{keV} \\cdot (\\textrm{BR}^{\\textrm{PDG}}_{f_2 \\pi}/...

  19. Buckling analysis of a cylindrical shell, under neutron radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Arani, A. Ghorbanpour [Department of Mechanical Engineering, School of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Ahmadi, M. [School of Research and Development of Nuclear Reactors and Accelerators, Nuclear Science and Technology (Iran, Islamic Republic of); Ahmadi, A. [Department of Management, University of Tehran, Tehran (Iran, Islamic Republic of); Rastgoo, A. [Department of Mechanical Engineering, School of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Sepyani, H.A., E-mail: hosepiani@yahoo.com [Department of Mechanical Engineering, School of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer The work investigates the buckling of a shell in the neutron radiation environment. Black-Right-Pointing-Pointer Radiation induced porosity in elastic materials affects the material's properties. Black-Right-Pointing-Pointer The data based technique was used to determine the volume fraction porosity. Black-Right-Pointing-Pointer The theoretical formulations are presented based on the classical shell theory (CST). Black-Right-Pointing-Pointer It was concluded that both T and neutron induced swelling have significant effects. - Abstract: This research investigates the buckling of a cylindrical shell in the neutron radiation environment, subjected to combined static and periodic axial forces. Radiation induced porosity in elastic materials affects the thermal, electrical and mechanical properties of the materials. In this study, the data based technique was used to determine the volume fraction porosity, P, of shell material. A least-squares fit of the Young's module data yielded the estimated Young's modulus. The shell assumed made of iron irradiated in the range of 2-15e-7 dPa/s at 345-650 Degree-Sign C and theoretical formulations are presented based on the classical shell theory (CST). The research deals with the problem theoretically; keeping in mind that one means of generating relevant design data is to investigate prototype structures. A parametric study is followed and the stability of shell is discussed. It is concluded that both temperature and neutron induced swelling have significant effects on the buckling load.

  20. Radiative Neutron Capture on Carbon-14 in Effective Field Theory

    CERN Document Server

    Rupak, Gautam; Vaghani, Akshay

    2012-01-01

    The cross section for radiative capture of neutron on carbon-14 is calculated using the model-independent formalism of halo effective field theory. The dominant contribution from E1 transition is considered, and the cross section is expressed in terms of elastic scattering parameters of the effective range expansion. Contributions from both resonant and non-resonant interaction are calculated. Significant interference between these leads to a capture contribution that deviates from simple Breit-Wigner resonance form.

  1. Radiation damage in silicon photomultipliers exposed to neutron radiation

    Science.gov (United States)

    Musienko, Yu.; Heering, A.; Ruchti, R.; Wayne, M.; Andreev, Yu.; Karneyeu, A.; Postoev, V.

    2017-07-01

    We studied performances of two SiPMs before and after irradiation at the Lubljana reactor. These high density (15 μ m cell pitch size) SiPMs were developed by Hamamatsu (in cooperation with the CMS SiPM group) for the CMS HCAL Upgrade Phase I project. The S10943-4732 is a photosensor selected for the CMS HE HCAL where the SiPMs will be exposed to 2× 1011 n/cm2 (1 MeV equivalent) for the operation time of the SLHC (integrated luminosity—5000 fb-1). The HD-1015CN SiPM was developed using new Hamamatsu trench technology to reduce optical cross-talk (X-talk) between SiPM cells. Both SiPMs are considered as candidates for the CMS HCAL barrel upgrade. The SiPMs were irradiated with reactor neutrons up to 1 MeV equivalent fluence of 2× 1012 n/cm2 (that corresponds to the maximum integrated neutron fluence in the HCAL barrel for the duration of the SLHC operation).

  2. Estimations of neutron yield from beryllium target irradiated by SPring-8 hard synchrotron radiation

    CERN Document Server

    Gryaznykh, D A; Plokhoi, V V

    2000-01-01

    The possibility of creating a neutron source based on ''SPring-8'' synchrotron radiation interaction with beryllium targets is discussed. The possible neutron yield is estimated to be of order 10 sup 1 sup 2 s sup - sup 1 .

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

    CERN Document Server

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

    2014-01-01

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

  4. Rechargeable solid state neutron detector and visible radiation indicator

    Energy Technology Data Exchange (ETDEWEB)

    Stowe, Ashley C.; Wiggins, Brenden; Burger, Arnold

    2017-05-23

    A radiation detection device, including: a support structure; and a chalcopyrite crystal coupled to the support structure; wherein, when the chalcopyrite crystal is exposed to radiation, a visible spectrum of the chalcopyrite crystal changes from an initial color to a modified color. The visible spectrum of the chalcopyrite crystal is changed back from the modified color to the initial color by annealing the chalcopyrite crystal at an elevated temperature below a melting point of the chalcopyrite crystal over time. The chalcopyrite crystal is optionally a .sup.6LiInSe.sub.2 crystal. The radiation is comprised of neutrons that decrease the .sup.6Li concentration of the chalcopyrite crystal via a .sup.6Li(n,.alpha.) reaction. The initial color is yellow and the modified color is one of orange and red. The annealing temperature is between about 450 degrees C. and about 650 degrees C. and the annealing time is between about 12 hrs and about 36 hrs.

  5. Neutron radiation damage and recovery studies of SiPMs

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, T.; Rao, T.; Stoll, S.; Woody, C.

    2016-12-01

    We characterized the performance of Silicon Photomultipliers (SiPMs) before and after exposure of up to 1012 neutron/cm2 dosage. We show that the typical orders of magnitude increase of dark current upon neutron irradiation can be suppressed by operating it at a lower temperature and single-photoelectron detection capability can be restored. The required operating temperature depends on the dosage received. Furthermore, after high temperature thermal annealing, there is compelling evidence that the extrinsic dark current is lowered by orders of magnitude and single-photon detection performance are to some extent recovered at room temperature. Our experimental findings might have widespread implications for extending the functionality and the useful lifetime of current and future large scale SiPM detectors deployed in ionization radiation environment.

  6. Neutron radiation damage and recovery studies of SiPMs

    Science.gov (United States)

    Tsang, T.; Rao, T.; Stoll, S.; Woody, C.

    2016-12-01

    We characterized the performance of Silicon Photomultipliers (SiPMs) before and after exposure of up to 1012 neutron/cm2 dosage. We show that the typical orders of magnitude increase of dark current upon neutron irradiation can be suppressed by operating it at a lower temperature and single-photoelectron detection capability can be restored. The required operating temperature depends on the dosage received. Furthermore, after high temperature thermal annealing, there is compelling evidence that the extrinsic dark current is lowered by orders of magnitude and single-photon detection performance are to some extent recovered at room temperature. Our experimental findings might have widespread implications for extending the functionality and the useful lifetime of current and future large scale SiPM detectors deployed in ionization radiation environment.

  7. Effect of neutron and proton radiations on magnetization of biotite

    CERN Document Server

    Abdurakhimov, A U; Sharipov, S M; Yugaj, V P; Granovskij, A B; Radkovskaya, A A

    2002-01-01

    One analyzes curves of field dependence of magnetization of biotite measured in the initial state under 4.2 K temperature subsequent to irradiation of 14 MeV energy and 1.2 x 10 sup 1 sup 3 cm sup - sup 2 dose neutrons and by 3 MeV energy and 2.2 x 10 sup 1 sup 4 cm sup - sup 2 dose protons, as well as, subsequent to annealing under 1000 deg temperature during 15 min. Irradiation by neutrons and protons was determined to result in increase of magneto-ordered phase content in biotite and, thus, in increase of magnetization of specimen. It is accounted for by formation of oxides in melt radiation thermal peaks and by freezing of high-temperature phase states corresponding to magnetite or solid solution of magnetite and hematite there. Thermal treatment does not change content of magneto-ordered phase in specimens

  8. A preliminary area survey of neutron radiation levels associated with the NASA variable energy cyclotron horizontal neutron delivery system

    Science.gov (United States)

    Roberts, W. K.; Leonard, R. F.

    1976-01-01

    The 25 MeV deuteron beam from the NASA variable energy cyclotron incident on a thick beryllium target will deliver a tissue neutron dose rate of 2.14 rad micron A-min at a source to skin distance of 125 cm. A neutron survey of the existing hallways with various shielding configurations made during operating of the horizontal neutron delivery system indicates that minimal amounts of additional neutron shielding material are required to provide a low level radiation environment within a self-contained neutron therapy control station. Measurements also indicate that the primary neutron distribution delivered by a planned vertical delivery system will be minimally perturbed by neutrons backscattered from the floor.

  9. Optimization of Thermal Neutron Converter in SiC Sensors for Spectral Radiation Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Krolikowski, Igor; Cetnar, Jerzy [Department of Nuclear Energy, Faculty of Energy and Fuels at AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Issa, Fatima; Ferrone, Raffaello; Ottaviani, Laurent [IM2NP, UMR CNRS 7334, Aix-Marseille University, Case 231, 13397 Marseille Cedex 20 (France); Szalkai, Dora; Klix, Axel [KIT- Karlsruhe Institute of Technology, Institute of Neutron Physics and Reactor Technology, Karlsruhe 76344 (Germany); Vermeeren, Ludo [SCK-CEN, Boeretang 200, B-2400 Mol (Belgium); Lyoussi, Abdalla [CEA, DEN, DER, Instrumentation Sensors and Dosimetry Laboratory, Cadarache, F-13108 St-Paul-Lez-Durance (France); Saenger, Richard [Etudes et Productions Schlumberger, Clamart (France)

    2015-07-01

    Optimization of the neutron converter in SiC sensors is presented. The sensors are used for spectral radiation measurements of thermal and fast neutrons and optionally gamma ray at elevated temperature in harsh radiation environment. The neutron converter, which is based on 10B, allows to detect thermal neutrons by means of neutron capture reaction. Two construction of the sensors were used to measure radiation in experiments. Sensor responses collected in experiments have been reproduced by the computer tool created by authors, it allows to validate the tool. The tool creates the response matrix function describing the characteristic of the sensors and it was used for detailed analyses of the sensor responses. Obtained results help to optimize the neutron converter in order to increase thermal neutron detection. Several enhanced construction of the sensors, which includes the neutron converter based on {sup 10}B or {sup 6}Li, were proposed. (authors)

  10. Neutron Radiation Effect On 2N2222 And NTE 123 NPN Silicon Bipolar Junction Transistors

    Science.gov (United States)

    Oo, Myo Min; Rashid, N. K. A. Md; Karim, J. Abdul; Zin, M. R. Mohamed; Hasbullah, N. F.

    2013-12-01

    This paper examines neutron radiation with PTS (Pneumatic Transfer System) effect on silicon NPN bipolar junction transistors (2N2222 and NTE 123) and analysis of the transistors in terms of electrical characterization such as current gain after neutron radiation. The key parameters are measured with Keithley 4200SCS. Experiment results show that the current gain degradation of the transistors is very sensitive to neutron radiation. The neutron radiation can cause displacement damage in the bulk layer of the transistor structure. The current degradation is believed to be governed by increasing recombination current between the base and emitter depletion region.

  11. Simulation of neutron radiation damage in silicon semiconductor devices.

    Energy Technology Data Exchange (ETDEWEB)

    Shadid, John Nicolas; Hoekstra, Robert John; Hennigan, Gary Lee; Castro, Joseph Pete Jr.; Fixel, Deborah A.

    2007-10-01

    A code, Charon, is described which simulates the effects that neutron damage has on silicon semiconductor devices. The code uses a stabilized, finite-element discretization of the semiconductor drift-diffusion equations. The mathematical model used to simulate semiconductor devices in both normal and radiation environments will be described. Modeling of defect complexes is accomplished by adding an additional drift-diffusion equation for each of the defect species. Additionally, details are given describing how Charon can efficiently solve very large problems using modern parallel computers. Comparison between Charon and experiment will be given, as well as comparison with results from commercially-available TCAD codes.

  12. New detectors of neutron, gamma- and X-radiations

    CERN Document Server

    Lobanov, N S

    2002-01-01

    Paper presents new detectors to record absorbed doses of neutron, gamma- and X-ray radiations within 0-1500 Mrad range. DBF dosimeter is based on dibutyl phthalate. EDS dosimeter is based on epoxy (epoxide) resin, while SD 5-40 detector is based on a mixture of dibutyl phthalate and epoxy resin. Paper describes experimental techniques to calibrate and interprets the measurement results of absorbed doses for all detectors. All three detectors cover 0-30000 Mrad measured does range. The accuracy of measurements is +- 10% independent (practically) of irradiation dose rates within 20-2000 rad/s limits under 20-80 deg C temperature

  13. Direct Radiative Capture of Neutron in Drip-Line Nuclei

    Institute of Scientific and Technical Information of China (English)

    LIU Zu-Hua; ZHANG Xi-Zhen; ZHANG Huan-Qiao

    2004-01-01

    @@ The analytic expressions of radial matrix elements , and in a finite square-well potential are derived. Based on these analytic expressions of radial matrix elements, the neutron direct radiative capture (DRC) processes leading to bound p-orbit from incident s-wave, and leading to s- and d-orbits from incident p-wave are discussed. For the DRC processes leading to loosely bound orbits, the dominant contributions to the radial matrix elements come from the outer region of nuclear potential radius R.

  14. Measurement of the radiative decay width {gamma}[{lambda}(1520)->{lambda}{gamma}] with the SPHINX spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, Yu.M. [Institute for High Energy Physics, Protvino (Russian Federation); Artamonov, A.V. [Institute for High Energy Physics, Protvino (Russian Federation); Batarin, V.A. [Institute for High Energy Physics, Protvino (Russian Federation); Vavilov, D.V. [Institute for High Energy Physics, Protvino (Russian Federation); Victorov, V.A. [Institute for High Energy Physics, Protvino (Russian Federation); Eroshin, O.V. [Institute for High Energy Physics, Protvino (Russian Federation); Golovkin, S.V. [Institute for High Energy Physics, Protvino (Russian Federation); Gorin, Yu.P. [Institute for High Energy Physics, Protvino (Russian Federation); Kolganov, V.Z. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Kozhevnikov, A.P. [Institute for High Energy Physics, Protvino (Russian Federation); Konstantinov, A.S. [Institute for High Energy Physics, Protvino (Russian Federation); Kubarovsky, V.P. [Institute for High Energy Physics, Protvino (Russian Federation); Kurshetsov, V.F. [Institute for High Energy Physics, Protvino (Russian Federation); Landsberg, L.G. [Institute for High Energy Physics, Protvino (Russian Federation)]. E-mail: lgl@mx.ihep.su; Leontiev, V.M. [Institute for High Energy Physics, Protvino (Russian Federation); Lomkatsi, G.S. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Molchanov, V.V. [Institute for High Energy Physics, Protvino (Russian Federation)]. E-mail: molchanov@mx.ihep.su; Mukhin, V.A. [Institute for High Energy Physics, Protvino (Russian Federation); Nilov, A.F. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation); Patalakha, D.I. [Institute for High Energy Physics, Protvino (Russian Federation); Petrenko, S.V. [Institute for High Energy Physics, Protvino (Russian Federation); Smolyankin, V.T. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)

    2004-12-16

    The radiative decay {lambda}(1520)->{lambda}{gamma} was measured directly in the study of the exclusive diffractive-like reaction p+N->{lambda}(1520)K{sup +}+N, {lambda}(1520)->{lambda}{gamma} with the SPHINX spectrometer. The values of the branching and partial width of this radiative decay were obtained: BR[{lambda}(1520)->{lambda}{gamma}]=(1.02+/-0.21(stat)+/-0.15(syst))x10{sup -2} and {gamma}[{lambda}(1520)->{lambda}{gamma}]=159+/-33(stat)+/-26(syst)-bar keV.

  15. Neutron radiation therapy: application of advanced technology to the treatment of cancer

    CERN Document Server

    Maughan, R L; Kota, C; Burmeister, J; Porter, A T; Forman, J D; Blosser, H G; Blosser, E; Blosser, G

    1999-01-01

    The design and construction of a unique superconducting cyclotron for use in fast neutron radiation therapy is described. The clinical results obtained in the treatment of adenocarcinoma of the prostate with this accelerator are presented. Future use of the boron neutron capture reaction as a means of enhancing fast neutron therapy in the treatment of patients with brain tumors (glioblastoma multiforme) is also discussed.

  16. Radiative Decay Width of Neutral non-Strange Baryons from PWA

    Directory of Open Access Journals (Sweden)

    Strakovsky Igor I.

    2015-01-01

    Full Text Available An overview of the GW SAID and ITEP groups effort to analyze pion photoproduction on the neutron-target will be given. The disentanglement the isoscalar and isovector EM couplings of N∗ and Δ∗ resonances does require compatible data on both proton and neutron targets. The final-state interaction plays a critical role in the state-of-the-art analysis in extraction of the γn → πN data from the deuteron target experiments. It is important component of the current JLab, MAMI-C, SPring-8, ELSA, and ELPH programs.

  17. Radiative Decay Width of Neutral non-Strange Baryons from PWA

    CERN Document Server

    Strakovsky, Igor I; Kudryavtsev, Alexander E; Kulikov, Viacheslav V; Martemyanov, Maxim A; Tarasov, Vladimir E

    2015-01-01

    An overview of the GW SAID and ITEP groups effort to analyze pion photoproduction on the neutron-target will be given. The disentanglement the isoscalar and isovector EM couplings of N* and Delta* resonances does require compatible data on both proton and neutron targets. The final-state interaction plays a critical role in the state-of-the-art analysis in extraction of the gamma n --> pi N data from the deuteron target experiments. It is important component of the current JLab, MAMI-C, SPring-8, ELSA, and ELPH programs

  18. A review of nanostructured based radiation sensors for neutron

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Pervaiz; Mohamed, Norani Muti; Burhanudin, Zainal Arif [Center of Excellence in Nanotechnology Department of Fundamental and Applied Sciences, Department of Electrical and Electronic Engineering Universiti Teknologi PETRONAS (Malaysia)

    2012-09-26

    Currently radiation sensors with various mechanisms such as radio thermo luminescence, radiographic and radiochromic film, semiconductor and ionization have been used for the detection of nuclear radiation. Sensitivity, handling procedure, heating condition, energy response, nonlinearity, polarization, non-uniform electric field, high bias voltage and spatial resolution due to large physical size are some of the key issues faced by these sensors. Due to the excellent electrical and mechanical properties, nanostructured materials such as carbon nanotubes (CNTs) have been researched as sensing elements in the sensors to overcome the mentioned problems. However CNTs are found to pose different problems, arising from the uncontrolled helicity and small cross-sectional area. Therefore, alternative sensing elements are still been sought after and the possibility of using boron nitride nanotubes for sensing neutron is considered in this review.

  19. Neutron and gamma radiation shielding material, structure, and process of making structure

    Energy Technology Data Exchange (ETDEWEB)

    Hondorp, H.L.

    1981-07-06

    The present invention is directed to a novel neutron and gamma radiation shielding material consisting of 95 to 97% by weight SiO/sub 2/ and 5 to 3% by weight sodium silicate. In addition, the method of using this composition to provide a continuous neutron and gamma radiation shielding structure is disclosed.

  20. Radiation shielding design for neutron diffractometers assisted by Monte Carlo methods

    Science.gov (United States)

    Osborn, John C.; Ersez, Tunay; Braoudakis, George

    2006-11-01

    Monte Carlo simulations may be used to model radiation shielding for neutron diffractometers. The use of the MCNP computer program to assess shielding for a diffractometer is discussed. A comparison is made of shielding requirements for radiation generated by several materials commonly used in neutron optical elements and beam stops, including lithium-6 based absorbers where the Monte Carlo method can model the effects of fast neutrons generated by this material.

  1. [Ozone therapy for radiation reactions and skin lesions after neutron therapy in patients with malignant tumors].

    Science.gov (United States)

    Velikaya, V V; Gribova, O V; Musabaeva, L I; Startseva, Zh A; Simonov, K A; Aleinik, A N; Lisin, V A

    2015-01-01

    The article discusses the problem of radiation complications from normal tissues in patients after therapy with fast neutrons of 6.3 MeV. The methods of treatment using ozone technologies in patients with radiation reactions and skin lesions on the areas of irradiation after neutron and neutron-photon therapy have been worked out. Ozone therapy showed its harmlessness and increased efficiency of complex treatment of these patients.

  2. Block-Based Compressed Sensing for Neutron Radiation Image Using WDFB

    Directory of Open Access Journals (Sweden)

    Wei Jin

    2015-01-01

    Full Text Available An ideal compression method for neutron radiation image should have high compression ratio while keeping more details of the original image. Compressed sensing (CS, which can break through the restrictions of sampling theorem, is likely to offer an efficient compression scheme for the neutron radiation image. Combining wavelet transform with directional filter banks, a novel nonredundant multiscale geometry analysis transform named Wavelet Directional Filter Banks (WDFB is constructed and applied to represent neutron radiation image sparsely. Then, the block-based CS technique is introduced and a high performance CS scheme for neutron radiation image is proposed. By performing two-step iterative shrinkage algorithm the problem of L1 norm minimization is solved to reconstruct neutron radiation image from random measurements. The experiment results demonstrate that the scheme not only improves the quality of reconstructed image obviously but also retains more details of original image.

  3. 20 years experience in radiobiology of neutron, and 10 years experience of neutron therapy in Obninsk, Russia. (Neutrons against cancer - the new methods in radiation therapy of tumors using nuclear reactor neutron beams)

    Energy Technology Data Exchange (ETDEWEB)

    Mardinsky, Y.S.; Oulianenko, S.E.; Obaturov, G.M. [Medical Radiological Research Center of Russian Academy of Medical Sciences, Obninsk (Russian Federation)] [and others

    1997-12-31

    New technology of radiation therapy, developed in Obninsk, is based on newly acquired knowledge in biological effects of neutrons. Detailed studies have been made of antitumor effectiveness of neutrons and of radiomodification factors action. Up till now more then 250 patients with tumors have been treated using reactor neutrons. Integral analysis of 5-year survival rates indicated a higher efficiency of neutron and mixed gamma-neutron therapy as compared with conventional radiation treatment. The survival rates were 89% for larynx cancer and 67% for breast cancer after neutron irradiation; the corresponding values were 65% and 46% after conventional radiation. The advantages of neutrons have been demonstrated both in loco-regional control and in overcoming of recurrences and metastasis

  4. Preliminary Status Report of Neutron Radiation Effects and Damage to Neutron Imaging System Equipment at Lawrence Livermore National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Bleuel, D. L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Anderson, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bernstein, L. A. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Brand, C. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brown, J. A. [Univ. of California, Berkeley, CA (United States); Caggiano, J. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); FItsos, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Goldblum, B. L. [Univ. of California, Berkeley, CA (United States); Hall, J. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Harrig, K. P. [Univ. of California, Berkeley, CA (United States); Johnson, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kruse, L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Laplace, T. A. [Univ. of California, Berkeley, CA (United States); Mahowald, M. [Univ. of California, Berkeley, CA (United States); Matthews, E. [Univ. of California, Berkeley, CA (United States); Nielson, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ratkiewicz, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rusnak, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Souza, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ureche, A. [Univ. of California, Berkeley, CA (United States); Ummel, C. [Univ. of California, Berkeley, CA (United States); Wiedrick, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Zeiser, F. [Univ. of Oslo (Norway)

    2017-02-08

    A high-intensity neutron source is being constructed at Lawrence Livermore National Laboratory (LLNL) to perform neutron imaging (NI). Two accelerators are be- ing installed in the shielded, underground, north cave of Building 194 to produce neutrons via deuterium- deuterium fusion at 4 MeV or 7 MeV in a windowless gas cell. Over months to years of future experiments, elec- tronic and mechanical equipment in the room will be ir- radiated by a large uence of neutrons, which could cause them to fail or function incorrectly. Neutrons will also activate equipment and materials in the room, making frequent maintenance di cult and time-consuming, ex- acerbating the consequence of equipment failure. To test the neutron response and failure probability of mission- critical components, a variety of equipment intended to be located closest to the neutron source was irradiated at Lawrence Berkeley National Laboratory's (LBNL's) 88-inch cyclotron, using neutrons produced from the breakup of deuterons impinging a thick beryllium target. The high neutron production and high neutron energy of this reaction in combination with the close-in geom- etry possible at the cyclotron allows the application of neutron doses expected to be delivered in months of NI facility operation in only a few days. In most cases, each piece of equipment was irradiated while powered, moni- tored remotely for failure, to test both its live response to irradiation in addition to permanent e ects. Aluminum activation foils were used as uence monitors, assuming the spectral shape measured by Meulders et. al.[1] While the neutron spectrum of the NI facility and the LBNL fa- cility were not identical, relative electronics and materials damage cross sections were used to equate an equivalent amount of energy-dependent neutron damage.

  5. Measurement of the leptonic decay width of $J/\\psi$ using initial state radiation

    CERN Document Server

    Ablikim, M; Ai, X C; Albayrak, O; Albrecht, M; Ambrose, D J; Amoroso, A; An, F F; An, Q; Bai, J Z; Ferroli, R Baldini; Ban, Y; Bennett, D W; Bennett, J V; Bertani, M; Bettoni, D; Bian, J M; Bianchi, F; Boger, E; Boyko, I; Briere, R A; Cai, H; Cai, X; Cakir, O; Calcaterra, A; Cao, G F; Cetin, S A; Chang, J F; Chelkov, G; Chen, G; Chen, H S; Chen, H Y; Chen, J C; Chen, M L; Chen, S J; Chen, X; Chen, X R; Chen, Y B; Cheng, H P; Chu, X K; Cibinetto, G; Dai, H L; Dai, J P; Dbeyssi, A; Dedovich, D; Deng, Z Y; Denig, A; Denysenko, I; Destefanis, M; De Mori, F; Ding, Y; Dong, C; Dong, J; Dong, L Y; Dong, M Y; Du, S X; Duan, P F; Eren, E E; Fan, J Z; Fang, J; Fang, S S; Fang, X; Fang, Y; Fava, L; Feldbauer, F; Felici, G; Feng, C Q; Fioravanti, E; Fritsch, M; Fu, C D; Gao, Q; Gao, X Y; Gao, Y; Gao, Z; Garzia, I; Geng, C; Goetzen, K; Gong, W X; Gradl, W; Greco, M; Gu, M H; Gu, Y T; Guan, Y H; Guo, A Q; Guo, L B; Guo, Y; Guo, Y P; Haddadi, Z; Hafner, A; Han, S; Han, Y L; Hao, X Q; Harris, F A; He, K L; He, Z Y; Held, T; Heng, Y K; Hou, Z L; Hu, C; Hu, H M; Hu, J F; Hu, T; Hu, Y; Huang, G M; Huang, G S; Huang, H P; Huang, J S; Huang, X T; Huang, Y; Hussain, T; Ji, Q; Ji, Q P; Ji, X B; Ji, X L; Jiang, L L; Jiang, L W; Jiang, X S; Jiang, X Y; Jiao, J B; Jiao, Z; Jin, D P; Jin, S; Johansson, T; Julin, A; Kalantar-Nayestanaki, N; Kang, X L; Kang, X S; Kavatsyuk, M; Ke, B C; Kiese, P; Kliemt, R; Kloss, B; Kolcu, O B; Kopf, B; Kornicer, M; Kühn, W; Kupsc, A; Lange, J S; Lara, M; Larin, P; Leng, C; Li, C; Li, C H; Li, Cheng; Li, D M; Li, F; Li, G; Li, H B; Li, J C; Li, Jin; Li, K; Li, K; Li, Lei; Li, P R; Li, T; Li, W D; Li, W G; Li, X L; Li, X M; Li, X N; Li, X Q; Li, Z B; Liang, H; Liang, Y F; Liang, Y T; Liao, G R; Lin, D X; Liu, B J; Liu, C X; Liu, F H; Liu, Fang; Liu, Feng; Liu, H B; Liu, H H; Liu, H H; Liu, H M; Liu, J; Liu, J B; Liu, J P; Liu, J Y; Liu, K; Liu, K Y; Liu, L D; Liu, P L; Liu, Q; Liu, S B; Liu, X; Liu, X X; Liu, Y B; Liu, Z A; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H; Lou, X C; Lu, H J; Lu, J G; Lu, R Q; Lu, Y; Lu, Y P; Luo, C L; Luo, M X; Luo, T; Luo, X L; Lv, M; Lyu, X R; Ma, F C; Ma, H L; Ma, L L; Ma, Q M; Ma, T; Ma, X N; Ma, X Y; Maas, F E; Maggiora, M; Mao, Y J; Mao, Z P; Marcello, S; Messchendorp, J G; Min, J; Min, T J; Mitchell, R E; Mo, X H; Mo, Y J; Morales, C Morales; Moriya, K; Muchnoi, N Yu; Muramatsu, H; Nefedov, Y; Nerling, F; Nikolaev, I B; Ning, Z; Nisar, S; Niu, S L; Niu, X Y; Olsen, S L; Ouyang, Q; Pacetti, S; Patteri, P; Pelizaeus, M; Peng, H P; Peters, K; Pettersson, J; Ping, J L; Ping, R G; Poling, R; Prasad, V; Pu, Y N; Qi, M; Qian, S; Qiao, C F; Qin, L Q; Qin, N; Qin, X S; Qin, Y; Qin, Z H; Qiu, J F; Rashid, K H; Redmer, C F; Ren, H L; Ripka, M; Rong, G; Rosner, Ch; Ruan, X D; Santoro, V; Sarantsev, A; Savrié, M; Schoenning, K; Schumann, S; Shan, W; Shao, M; Shen, C P; Shen, P X; Shen, X Y; Sheng, H Y; Song, W M; Song, X Y; Sosio, S; Spataro, S; Sun, G X; Sun, J F; Sun, S S; Sun, Y J; Sun, Y Z; Sun, Z J; Sun, Z T; Tang, C J; Tang, X; Tapan, I; Thorndike, E H; Tiemens, M; Ullrich, M; Uman, I; Varner, G S; Wang, B; Wang, B L; Wang, D; Wang, D Y; Wang, K; Wang, L L; Wang, L S; Wang, M; Wang, P; Wang, P L; Wang, S G; Wang, W; Wang, X F; Wang, Y D; Wang, Y F; Wang, Y Q; Wang, Z; Wang, Z G; Wang, Z H; Wang, Z Y; Weber, T; Wei, D H; Wei, J B; Weidenkaff, P; Wen, S P; Wiedner, U; Wolke, M; Wu, L H; Wu, Z; Xia, L G; Xia, Y; Xiao, D; Xiao, Z J; Xie, Y G; Xiu, Q L; Xu, G F; Xu, L; Xu, Q J; Xu, Q N; Xu, X P; Yan, L; Yan, W B; Yan, W C; Yan, Y H; Yang, H J; Yang, H X; Yang, L; Yang, Y; Yang, Y X; Ye, H; Ye, M; Ye, M H; Yin, J H; Yu, B X; Yu, C X; Yu, H W; Yu, J S; Yuan, C Z; Yuan, W L; Yuan, Y; Yuncu, A; Zafar, A A; Zallo, A; Zeng, Y; Zhang, B X; Zhang, B Y; Zhang, C; Zhang, C C; Zhang, D H; Zhang, H H; Zhang, H Y; Zhang, J J; Zhang, J L; Zhang, J Q; Zhang, J W; Zhang, J Y; Zhang, J Z; Zhang, K; Zhang, L; Zhang, S H; Zhang, X Y; Zhang, Y; Zhang, Y N; Zhang, Y H; Zhang, Y T; Zhang, Yu; Zhang, Z H; Zhang, Z P; Zhang, Z Y; Zhao, G; Zhao, J W; Zhao, J Y; Zhao, J Z; Zhao, Lei; Zhao, Ling; Zhao, M G; Zhao, Q; Zhao, Q W; Zhao, S J; Zhao, T C; Zhao, Y B; Zhao, Z G; Zhemchugov, A; Zheng, B; Zheng, J P; Zheng, W J; Zheng, Y H; Zhong, B; Zhou, L; Zhou, Li; Zhou, X; Zhou, X K; Zhou, X R; Zhou, X Y; Zhu, K; Zhu, K J; Zhu, S; Zhu, X L; Zhu, Y C; Zhu, Y S; Zhu, Z A; Zhuang, J; Zotti, L; Zou, B S; Zou, J H

    2016-01-01

    Using a data set of 2.93 fb$^{-1}$ taken at a center-of-mass energy of $\\sqrt{s}$ = 3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process $e^+e^-\\rightarrow J/\\psi\\gamma\\rightarrow \\mu^+\\mu^-\\gamma$ and determine the product of the branching fraction and the electronic width $\\mathcal B_{\\mu\\mu}\\cdot \\Gamma_{ee} = (333.4 \\pm 2.5_{\\rm stat} \\pm 4.4_{\\rm sys})$~eV. Using the earlier-published BESIII result for $\\mathcal B_{\\mu\\mu}$ = (5.973 $\\pm$ 0.007$_{\\rm stat}$ $\\pm$ 0.037$_{\\rm sys}$)\\%, we derive the $J/\\psi$ electronic width $\\Gamma_{ee}$~= (5.58 $\\pm$ 0.05$_{\\rm stat}$ $\\pm$ 0.08$_{\\rm sys}$) keV.

  6. Measurement of the leptonic decay width of J/ψ using initial state radiation

    Science.gov (United States)

    Ablikim, M.; Achasov, M. N.; Ai, X. C.; Albayrak, O.; Albrecht, M.; Ambrose, D. J.; Amoroso, A.; An, F. F.; An, Q.; Bai, J. Z.; Baldini Ferroli, R.; Ban, Y.; Bennett, D. W.; Bennett, J. V.; Bertani, M.; Bettoni, D.; Bian, J. M.; Bianchi, F.; Boger, E.; Boyko, I.; Briere, R. A.; Cai, H.; Cai, X.; Cakir, O.; Calcaterra, A.; Cao, G. F.; Cetin, S. A.; Chang, J. F.; Chelkov, G.; Chen, G.; Chen, H. S.; Chen, H. Y.; Chen, J. C.; Chen, M. L.; Chen, S. J.; Chen, X.; Chen, X. R.; Chen, Y. B.; Cheng, H. P.; Chu, X. K.; Cibinetto, G.; Dai, H. L.; Dai, J. P.; Dbeyssi, A.; Dedovich, D.; Deng, Z. Y.; Denig, A.; Denysenko, I.; Destefanis, M.; De Mori, F.; Ding, Y.; Dong, C.; Dong, J.; Dong, L. Y.; Dong, M. Y.; Du, S. X.; Duan, P. F.; Eren, E. E.; Fan, J. Z.; Fang, J.; Fang, S. S.; Fang, X.; Fang, Y.; Fava, L.; Feldbauer, F.; Felici, G.; Feng, C. Q.; Fioravanti, E.; Fritsch, M.; Fu, C. D.; Gao, Q.; Gao, X. Y.; Gao, Y.; Gao, Z.; Garzia, I.; Geng, C.; Goetzen, K.; Gong, W. X.; Gradl, W.; Greco, M.; Gu, M. H.; Gu, Y. T.; Guan, Y. H.; Guo, A. Q.; Guo, L. B.; Guo, Y.; Guo, Y. P.; Haddadi, Z.; Hafner, A.; Han, S.; Han, Y. L.; Hao, X. Q.; Harris, F. A.; He, K. L.; He, Z. Y.; Held, T.; Heng, Y. K.; Hou, Z. L.; Hu, C.; Hu, H. M.; Hu, J. F.; Hu, T.; Hu, Y.; Huang, G. M.; Huang, G. S.; Huang, H. P.; Huang, J. S.; Huang, X. T.; Huang, Y.; Hussain, T.; Ji, Q.; Ji, Q. P.; Ji, X. B.; Ji, X. L.; Jiang, L. L.; Jiang, L. W.; Jiang, X. S.; Jiang, X. Y.; Jiao, J. B.; Jiao, Z.; Jin, D. P.; Jin, S.; Johansson, T.; Julin, A.; Kalantar-Nayestanaki, N.; Kang, X. L.; Kang, X. S.; Kavatsyuk, M.; Ke, B. C.; Kiese, P.; Kliemt, R.; Kloss, B.; Kolcu, O. B.; Kopf, B.; Kornicer, M.; Kuehn, W.; Kupsc, A.; Lange, J. S.; Lara, M.; Larin, P.; Leng, C.; Li, C.; Li, C. H.; Li, Cheng; Li, D. M.; Li, F.; Li, G.; Li, H. B.; Li, J. C.; Li, Jin; Li, K.; Li, K.; Li, Lei; Li, P. R.; Li, T.; Li, W. D.; Li, W. G.; Li, X. L.; Li, X. M.; Li, X. N.; Li, X. Q.; Li, Z. B.; Liang, H.; Liang, Y. F.; Liang, Y. T.; Liao, G. R.; Lin, D. X.; Liu, B. J.; Liu, C. X.; Liu, F. H.; Liu, Fang; Liu, Feng; Liu, H. B.; Liu, H. H.; Liu, H. H.; Liu, H. M.; Liu, J.; Liu, J. B.; Liu, J. P.; Liu, J. Y.; Liu, K.; Liu, K. Y.; Liu, L. D.; Liu, P. L.; Liu, Q.; Liu, S. B.; Liu, X.; Liu, X. X.; Liu, Y. B.; Liu, Z. A.; Liu, Zhiqiang; Liu, Zhiqing; Loehner, H.; Lou, X. C.; Lu, H. J.; Lu, J. G.; Lu, R. Q.; Lu, Y.; Lu, Y. P.; Luo, C. L.; Luo, M. X.; Luo, T.; Luo, X. L.; Lv, M.; Lyu, X. R.; Ma, F. C.; Ma, H. L.; Ma, L. L.; Ma, Q. M.; Ma, T.; Ma, X. N.; Ma, X. Y.; Maas, F. E.; Maggiora, M.; Mao, Y. J.; Mao, Z. P.; Marcello, S.; Messchendorp, J. G.; Min, J.; Min, T. J.; Mitchell, R. E.; Mo, X. H.; Mo, Y. J.; Morales Morales, C.; Moriya, K.; Muchnoi, N. Yu.; Muramatsu, H.; Nefedov, Y.; Nerling, F.; Nikolaev, I. B.; Ning, Z.; Nisar, S.; Niu, S. L.; Niu, X. Y.; Olsen, S. L.; Ouyang, Q.; Pacetti, S.; Patteri, P.; Pelizaeus, M.; Peng, H. P.; Peters, K.; Pettersson, J.; Ping, J. L.; Ping, R. G.; Poling, R.; Prasad, V.; Pu, Y. N.; Qi, M.; Qian, S.; Qiao, C. F.; Qin, L. Q.; Qin, N.; Qin, X. S.; Qin, Y.; Qin, Z. H.; Qiu, J. F.; Rashid, K. H.; Redmer, C. F.; Ren, H. L.; Ripka, M.; Rong, G.; Rosner, Ch.; Ruan, X. D.; Santoro, V.; Sarantsev, A.; Savrié, M.; Schoenning, K.; Schumann, S.; Shan, W.; Shao, M.; Shen, C. P.; Shen, P. X.; Shen, X. Y.; Sheng, H. Y.; Song, W. M.; Song, X. Y.; Sosio, S.; Spataro, S.; Sun, G. X.; Sun, J. F.; Sun, S. S.; Sun, Y. J.; Sun, Y. Z.; Sun, Z. J.; Sun, Z. T.; Tang, C. J.; Tang, X.; Tapan, I.; Thorndike, E. H.; Tiemens, M.; Ullrich, M.; Uman, I.; Varner, G. S.; Wang, B.; Wang, B. L.; Wang, D.; Wang, D. Y.; Wang, K.; Wang, L. L.; Wang, L. S.; Wang, M.; Wang, P.; Wang, P. L.; Wang, S. G.; Wang, W.; Wang, X. F.; Wang, Y. D.; Wang, Y. F.; Wang, Y. Q.; Wang, Z.; Wang, Z. G.; Wang, Z. H.; Wang, Z. Y.; Weber, T.; Wei, D. H.; Wei, J. B.; Weidenkaff, P.; Wen, S. P.; Wiedner, U.; Wolke, M.; Wu, L. H.; Wu, Z.; Xia, L. G.; Xia, Y.; Xiao, D.; Xiao, H.; Xiao, Z. J.; Xie, Y. G.; Xiu, Q. L.; Xu, G. F.; Xu, L.; Xu, Q. J.; Xu, Q. N.; Xu, X. P.; Yan, L.; Yan, W. B.; Yan, W. C.; Yan, Y. H.; Yang, H. J.; Yang, H. X.; Yang, L.; Yang, Y.; Yang, Y. X.; Ye, H.; Ye, M.; Ye, M. H.; Yin, J. H.; Yu, B. X.; Yu, C. X.; Yu, H. W.; Yu, J. S.; Yuan, C. Z.; Yuan, W. L.; Yuan, Y.; Yuncu, A.; Zafar, A. A.; Zallo, A.; Zeng, Y.; Zhang, B. X.; Zhang, B. Y.; Zhang, C.; Zhang, C. C.; Zhang, D. H.; Zhang, H. H.; Zhang, H. Y.; Zhang, J. J.; Zhang, J. L.; Zhang, J. Q.; Zhang, J. W.; Zhang, J. Y.; Zhang, J. Z.; Zhang, K.; Zhang, L.; Zhang, S. H.; Zhang, X. Y.; Zhang, Y.; Zhang, Y. N.; Zhang, Y. H.; Zhang, Y. T.; Zhang, Yu; Zhang, Z. H.; Zhang, Z. P.; Zhang, Z. Y.; Zhao, G.; Zhao, J. W.; Zhao, J. Y.; Zhao, J. Z.; Zhao, Lei; Zhao, Ling; Zhao, M. G.; Zhao, Q.; Zhao, Q. W.; Zhao, S. J.; Zhao, T. C.; Zhao, Y. B.; Zhao, Z. G.; Zhemchugov, A.; Zheng, B.; Zheng, J. P.; Zheng, W. J.; Zheng, Y. H.; Zhong, B.; Zhou, L.; Zhou, Li; Zhou, X.; Zhou, X. K.; Zhou, X. R.; Zhou, X. Y.; Zhu, K.; Zhu, K. J.; Zhu, S.; Zhu, X. L.; Zhu, Y. C.; Zhu, Y. S.; Zhu, Z. A.; Zhuang, J.; Zotti, L.; Zou, B. S.; Zou, J. H.

    2016-10-01

    Using a data set of 2.93 fb-1 taken at a center-of-mass energy of √{ s} = 3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process e+e- → J / ψγ →μ+μ- γ and determine the product of the branching fraction and the electronic width Bμμ ṡΓee = (333.4 ±2.5stat ±4.4sys) eV. Using the earlier-published BESIII result for Bμμ = (5.973 ±0.007stat ±0.037sys)%, we derive the J / ψ electronic width Γee = (5.58 ±0.05stat ±0.08sys) keV.

  7. Measurement of the leptonic decay width of J/ψ using initial state radiation

    Directory of Open Access Journals (Sweden)

    M. Ablikim

    2016-10-01

    Full Text Available Using a data set of 2.93 fb−1 taken at a center-of-mass energy of s=3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process e+e−→J/ψγ→μ+μ−γ and determine the product of the branching fraction and the electronic width Bμμ⋅Γee=(333.4±2.5stat±4.4sys eV. Using the earlier-published BESIII result for Bμμ=(5.973±0.007stat±0.037sys%, we derive the J/ψ electronic width Γee=(5.58±0.05stat±0.08sys keV.

  8. Radiation damage study using small-angle neutron scattering

    Science.gov (United States)

    Rétfalvi, E.; Török, Gy; Rosta, L.

    2000-03-01

    Nuclear radiation provides important changes in the microstructure of metallic components of nuclear power plant and research reactors, influencing their mechanical properties. The investigation of this problem has primary interest for the safety and life-time of such nuclear installations. For the characterization of this kind of nanostructures small angle neutron scattering technique is a very useful tool. We have carried out experiments on samples of irradiated reactor vessel material and welded components of VVER-440-type reactors on the SANS instrument at the Budapest Research Reactor. In our measurements irradiated as well as non-irradiated samples were compared and magnetic field was applied for viewing the magnetic structure effects of the materials. A clear modification of the structure due to irradiation was obtained. Our data were analyzed by the ITP92 code, the inverse Fourier transform program of O. Glatter [1].

  9. Synchrotron microbeam radiation therapy for rat brain tumor palliation—influence of the microbeam width at constant valley dose

    Science.gov (United States)

    Serduc, Raphaël; Bouchet, Audrey; Bräuer-Krisch, Elke; Laissue, Jean A.; Spiga, Jenny; Sarun, Sukhéna; Bravin, Alberto; Fonta, Caroline; Renaud, Luc; Boutonnat, Jean; Siegbahn, Erik Albert; Estève, François; Le Duc, Géraldine

    2009-11-01

    To analyze the effects of the microbeam width (25, 50 and 75 µm) on the survival of 9L gliosarcoma tumor-bearing rats and on toxicity in normal tissues in normal rats after microbeam radiation therapy (MRT), 9L gliosarcomas implanted in rat brains, as well as in normal rat brains, were irradiated in the MRT mode. Three configurations (MRT25, MRT50, MRT75), each using two orthogonally intersecting arrays of either 25, 50 or 75 µm wide microbeams, all spaced 211 µm on center, were tested. For each configuration, peak entrance doses of 860, 480 and 320 Gy, respectively, were calculated to produce an identical valley dose of 18 Gy per individual array at the center of the tumor. Two, 7 and 14 days after radiation treatment, 42 rats were killed to evaluate histopathologically the extent of tumor necrosis, and the presence of proliferating tumors cells and tumor vessels. The median survival times of the normal rats were 4.5, 68 and 48 days for MRT25, 50 and 75, respectively. The combination of the highest entrance doses (860 Gy per array) with 25 µm wide beams (MRT25) resulted in a cumulative valley dose of 36 Gy and was excessively toxic, as it led to early death of all normal rats and of ~50% of tumor-bearing rats. The short survival times, particularly of rats in the MRT25 group, restricted adequate observance of the therapeutic effect of the method on tumor-bearing rats. However, microbeams of 50 µm width led to the best median survival time after 9L gliosarcoma MRT treatment and appeared as the better compromise between tumor control and normal brain toxicity compared with 75 µm or 25 µm widths when used with a 211 µm on-center distance. Despite very high radiation doses, the tumors were not sterilized; viable proliferating tumor cells remained present at the tumor margin. This study shows that microbeam width and peak entrance doses strongly influence tumor responses and normal brain toxicity, even if valley doses are kept constant in all groups. The use of

  10. Synchrotron microbeam radiation therapy for rat brain tumor palliation-influence of the microbeam width at constant valley dose

    Energy Technology Data Exchange (ETDEWEB)

    Serduc, Raphael; Fonta, Caroline; Renaud, Luc [Universite de Toulouse, UPS, Centre de Recherche Cerveau et Cognition (France); Bouchet, Audrey; Braeuer-Krisch, Elke; Sarun, Sukhena; Bravin, Alberto; Le Duc, Geraldine [European Synchrotron Radiation Facility, F38043 Grenoble (France); Laissue, Jean A [Institute of Pathology, University of Bern (Switzerland); Spiga, Jenny [Department of Physics, University of Cagliari, s.p. Monserrato-Sestu, Monserrato (Canada) 09042 (Italy); Boutonnat, Jean [TIMC lab, UMR CNRS 5525, Univ Joseph Fourier, CHU, Grenoble (France); Siegbahn, Erik Albert [Department of Medical Physics, Karolinska Universitetssjukhuset, 17176 Stockholm (Sweden); Esteve, Francois [INSERM U836, Equipe 6, Institut des Neurosciences de Grenoble, 38043 Grenoble Cedex (France)], E-mail: raph.serduc@gmail.com

    2009-11-07

    To analyze the effects of the microbeam width (25, 50 and 75 {mu}m) on the survival of 9L gliosarcoma tumor-bearing rats and on toxicity in normal tissues in normal rats after microbeam radiation therapy (MRT), 9L gliosarcomas implanted in rat brains, as well as in normal rat brains, were irradiated in the MRT mode. Three configurations (MRT25, MRT50, MRT75), each using two orthogonally intersecting arrays of either 25, 50 or 75 {mu}m wide microbeams, all spaced 211 {mu}m on center, were tested. For each configuration, peak entrance doses of 860, 480 and 320 Gy, respectively, were calculated to produce an identical valley dose of 18 Gy per individual array at the center of the tumor. Two, 7 and 14 days after radiation treatment, 42 rats were killed to evaluate histopathologically the extent of tumor necrosis, and the presence of proliferating tumors cells and tumor vessels. The median survival times of the normal rats were 4.5, 68 and 48 days for MRT25, 50 and 75, respectively. The combination of the highest entrance doses (860 Gy per array) with 25 {mu}m wide beams (MRT25) resulted in a cumulative valley dose of 36 Gy and was excessively toxic, as it led to early death of all normal rats and of {approx}50% of tumor-bearing rats. The short survival times, particularly of rats in the MRT25 group, restricted adequate observance of the therapeutic effect of the method on tumor-bearing rats. However, microbeams of 50 {mu}m width led to the best median survival time after 9L gliosarcoma MRT treatment and appeared as the better compromise between tumor control and normal brain toxicity compared with 75 {mu}m or 25 {mu}m widths when used with a 211 {mu}m on-center distance. Despite very high radiation doses, the tumors were not sterilized; viable proliferating tumor cells remained present at the tumor margin. This study shows that microbeam width and peak entrance doses strongly influence tumor responses and normal brain toxicity, even if valley doses are kept constant in

  11. Hot Radiative Accretion onto a Spinning Neutron Star

    CERN Document Server

    Medvedev, M V

    2004-01-01

    (Abridged) A new type of self-similar hot viscous radiative accretion flow onto a rapidly spinning neutron star has recently been discovered. This ``hot brake'' flow forms in the two-temperature zone (close to a central object), but at a sufficiently low accretion rate and a high spin it may extend in the radial direction beyond ~300 Schwarzchild radii into a one-temperature zone. When the spin of the star is small enough, the flow transforms smoothly to an advection-dominated accretion flow. All gas parameters (density, angular velocity, temperature, luminosity, angular momentum flux) except for the radial velocity are independent of the mass accretion rate. The radiative efficiency may be arbitrarily large as M-dot -> 0. The gas angular momentum is transported outward under most conditions, hence the central star is nearly always spun-down. The flow is convectively stable. We also find that themal conduction in the flow is strong enough to make the flow thermally stable. The very fact that the density, temp...

  12. Neutron flux spectra and radiation damage parameters for the Russian Bor-60 and SM-2 reactors

    Energy Technology Data Exchange (ETDEWEB)

    Karasiov, A.V. [D.V. Efremov Scientific Rresearch Institute of Electrophysical Apparatus, St. Petersburg (Russian Federation); Greenwood, L.R. [Pacific Northwest Laboratory, Richland, WA (United States)

    1995-04-01

    The objective is to compare neutron irradiation conditions in Russian reactors and similar US facilities. Neutron fluence and spectral information and calculated radiation damage parameters are presented for the BOR-60 (Fast Experimental Reactor - 60 MW) and SM-2 reactors in Russia. Their neutron exposure characteristics are comparable with those of the Experimental Breeder Reactor (ERB-II), the Fast Flux Test Facility (FFTF), and the High Flux Isotope Reactor (HFIR) in the United States.

  13. Neutron spectra and dose equivalents calculated in tissue for high-energy radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kry, Stephen F.; Howell, Rebecca M.; Salehpour, Mohammad; Followill, David S. [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)

    2009-04-15

    Neutrons are by-products of high-energy radiation therapy and a source of dose to normal tissues. Thus, the presence of neutrons increases a patient's risk of radiation-induced secondary cancer. Although neutrons have been thoroughly studied in air, little research has been focused on neutrons at depths in the patient where radiosensitive structures may exist, resulting in wide variations in neutron dose equivalents between studies. In this study, we characterized properties of neutrons produced during high-energy radiation therapy as a function of their depth in tissue and for different field sizes and different source-to-surface distances (SSD). We used a previously developed Monte Carlo model of an accelerator operated at 18 MV to calculate the neutron fluences, energy spectra, quality factors, and dose equivalents in air and in tissue at depths ranging from 0.1 to 25 cm. In conjunction with the sharply decreasing dose equivalent with increased depth in tissue, the authors found that the neutron energy spectrum changed drastically as a function of depth in tissue. The neutron fluence decreased gradually as the depth increased, while the average neutron energy decreased sharply with increasing depth until a depth of approximately 7.5 cm in tissue, after which it remained nearly constant. There was minimal variation in the quality factor as a function of depth. At a given depth in tissue, the neutron dose equivalent increased slightly with increasing field size and decreasing SSD; however, the percentage depth-dose equivalent curve remained constant outside the primary photon field. Because the neutron dose equivalent, fluence, and energy spectrum changed substantially with depth in tissue, we concluded that when the neutron dose equivalent is being determined at a depth within a patient, the spectrum and quality factor used should be appropriate for depth rather than for in-air conditions. Alternately, an appropriate percent depth-dose equivalent curve

  14. Measurement of radiative widths of a{sub 2}(1320) and π{sub 2}(1670)

    Energy Technology Data Exchange (ETDEWEB)

    Adolph, C.; Braun, C.; Eyrich, W.; Lehmann, A.; Schmidt, A. [Physikalisches Institut, Universitaet Erlangen-Nuernberg, Erlangen (Germany); Akhunzyanov, R.; Alexeev, G.D.; Anosov, V.; Efremov, A.; Gavrichtchouk, O.P.; Guskov, A.; Ivanov, A.; Ivanshin, Yu.; Kisselev, Yu.; Kouznetsov, O.; Kroumchtein, Z.V.; Kuchinski, N.; Meshcheryakov, G.; Nagaytsev, A.; Orlov, I.; Olshevsky, A.G.; Rossiyskaya, N.S.; Savin, I.A.; Shevchenko, O.Yu.; Slunecka, M.; Zemlyanichkina, E. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Alexeev, M.G.; Birsa, R.; Dalla Torre, S.; Dasgupta, S.; Gobbo, B.; Levorato, S.; Sozzi, F.; Steiger, L.; Tessaro, S.; Tessarotto, F. [Trieste Section of INFN, Trieste (Italy); Amoroso, A.; Balestra, F.; Chiosso, M.; Gnesi, I.; Grasso, A.; Kotzinian, A.M.; Parsamyan, B.; Sosio, S. [Department of Physics, University of Turin, Turin (Italy); Torino Section of INFN, Turin (Italy); Andrieux, V.; Bedfer, Y.; Boer, M.; Burtin, E.; Capozza, L.; Curiel, Q.; Ferrero, A.; Hose, N. d' ; Kunne, F.; Magnon, A.; Marchand, C.; Neyret, D.; Platchkov, S.; Thibaud, F.; Vandenbroucke, M.; Wollny, H. [CEA IRFU/SPhN Saclay, Gif-sur-Yvette (France); Austregesilo, A.; Bicker, K. [CERN, Geneva 23 (Switzerland); Physik Department, Technische Universitaet Muenchen, Garching (Germany); Badelek, B. [Faculty of Physics, University of Warsaw, Warsaw (Poland); Barth, J.; Bieling, J.; Goertz, S.; Hahne, D.; Klein, F.; Panknin, R.; Pretz, J.; Schmieden, H.; Windmolders, R. [Physikalisches Institut, Universitaet Bonn, Bonn (Germany); Baum, G. [Fakultaet fuer Physik, Universitaet Bielefeld, Bielefeld (Germany); Beck, R.; Bisplinghoff, J.; Eversheim, P.D.; Hinterberger, F.; Jahn, R.; Joosten, R. [Helmholtz-Institut fuer Strahlen- und Kernphysik, Universitaet Bonn, Bonn (Germany); Berlin, A.; Gautheron, F.; Koivuniemi, J.H.; Meyer, W.; Reicherz, G.; Wang, L. [Institut fuer Experimentalphysik, Universitaet Bochum, Bochum (Germany); Bernhard, J.; Harrach, D. von; Jasinski, P.; Kabuss, E.; Nerling, F.; Ostrick, M.; Pochodzalla, J.; Weisrock, T.; Wilfert, M. [Institut fuer Kernphysik, Universitaet Mainz, Mainz (Germany); Bodlak, M.; Finger, M.; Finger, M.; Matousek, J.; Pesek, M. [Faculty of Mathematics and Physics, Charles University in Prague, Prague (Czech Republic); Bordalo, P.; Franco, C.; Nunes, A.S.; Quaresma, M.; Quintans, C.; Ramos, S.; Silva, L.; Stolarski, M. [LIP, Lisbon (Portugal); Bradamante, F. [CERN, Geneva 23 (Switzerland); Department of Physics, University of Trieste, Trieste (Italy); Bressan, A.; Elia, C.; Makke, N.; Martin, A.; Sbrizzai, G.; Schiavon, P. [Trieste Section of INFN, Trieste (Italy); Department of Physics, University of Trieste, Trieste (Italy); Buechele, M.; Fischer, H.; Gorzellik, M.; Guthoerl, T.; Heinsius, F.H.; Herrmann, F.; Joerg, P.; Koenigsmann, K.; Nowak, W.D.; Schill, C.; Schmidt, K.; Schopferer, S.; Sirtl, S.; Szameitat, T.; Ter Wolbeek, J. [Physikalisches Institut, Universitaet Freiburg, Freiburg (Germany); Chung, S.U.; Friedrich, J.M.; Grabmueller, S.; Grube, B.; Haas, F.; Hoeppner, C.; Huber, S.; Ketzer, B.; Kraemer, M.; Nagel, T.; Neubert, S.; Paul, S.; Uhl, S. [Physik Department, Technische Universitaet Muenchen, Garching (Germany); Cicuttin, A.; Crespo, M.L. [Trieste Section of INFN, Trieste (Italy); Abdus Salam ICTP, Trieste (Italy); Dasgupta, S.S.; Sarkar, S.; Sinha, L. [Matrivani Institute of Experimental Research and Education, Calcutta (India); Denisov, O.Yu.; Maggiora, A.; Takekawa, S. [Torino Section of INFN, Turin (Italy); Donskov, S.V.; Filin, A.; Khaustov, G.V.; Khokhlov, Yu.A.; Kolosov, V.N.; Konstantinov, V.F.; Lednev, A.A.; Mikhailov, Yu.V.; Nikolaenko, V.I.; Polyakov, V.A.; Ryabchikov, D.I.; Samoylenko, V.D. [State Scientific Center Institute for High Energy Physics of National Research Center ' ' Kurchatov Institute' ' , Protvino (Russian Federation); Doshita, N.; Hashimoto, R.; Ishimoto, S.; Iwata, T.; Kondo, K.; Matsuda, H.; Michigami, T.; Miyachi, Y.; Suzuki, H. [Yamagata University, Yamagata (Japan); Duic, V. [Department of Physics, University of Trieste, Trieste (Italy); Duennweber, W.; Faessler, M.; Geyer, R.; Schlueter, T.; Uman, I. [Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Munich (Germany); Dziewiecki, M.; Kurjata, R.P.; Marzec, J.; Rychter, A.; Zaremba, K.; Ziembicki, M. [Institute of Radioelectronics, Warsaw University of Technology, Warsaw (Poland); Fresne von Hohenesche, N. du [CERN, Geneva 23 (Switzerland); Institut fuer Kernphysik, Universitaet Mainz, Mainz (Germany); Frolov, V.; Mallot, G.K.; Rocco, E.; Schoenning, K.; Schott, M. [CERN, Geneva 23 (Switzerland); Gerassimov, S.; Konorov, I. [Lebedev Physical Institute, Moscow (Russian Federation); Physik Department, Technische Universitaet Muenchen, Garching (Germany); Horikawa, N. [Nagoya University, Nagoya (Japan); Jary, V.; Kral, Z.; Novy, J.; Virius, M.; Vondra, J. [Czech Technical University in Prague, Prague (Czech Republic); Klimaszewski, K.; Kurek, K.; Sandacz, A.; Sulej, R.; Szabelski, A.; Sznajder, P. [National Centre for Nuclear Research, Warsaw (PL); Panzieri, D. [Torino Section of INFN, Turin (IT); University of Eastern Piedmont, Alessandria (IT); Srnka, A. [Institute of Scientific Instruments, AS CR, Brno (CZ); Sulc, M. [Technical University in Liberec, Liberec (CZ); Zavertyaev, M. [Lebedev Physical Institute, Moscow (RU); Matsuda, T. [University of Miyazaki, Miyazaki (JP); Lichtenstadt, J. [School of Physics and Astronomy, Tel Aviv University, Tel Aviv (IL)

    2014-04-15

    The COMPASS Collaboration at CERN has investigated the reaction π{sup -}γ → π{sup -}π{sup -}π{sup +} embedded in the Primakoff reaction of 190 GeV pions scattering in the Coulomb field of a lead target, π{sup -}Pb → π{sup -}π{sup -}π{sup +} Pb. Exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at momentum transfer below 0.001 (GeV/c){sup 2}. Using a partial-wave analysis the amplitudes and relative phases of the a{sub 2}(1320) and π{sub 2}(1670) mesons have been extracted, and the Coulomb and the diffractive contributions have been disentangled. Measuring absolute production cross sections we have determined the radiative width of the a{sub 2}(1320) to be Γ{sub 0}(a{sub 2}(1320) → πγ) = (358 ± 6{sub stat} ± 42{sub syst}) keV. As the first measurement, Γ{sub 0}(π{sub 2}(1670) → πγ) = (181 ± 11{sub stat} ± 27{sub syst}) keV . (BR{sup PDG}{sub f{sub 2π}}/BR{sub f{sub 2π}}) is obtained for the radiative width of the π{sub 2}(1670), where in this analysis the branching ratio BR{sup PDG}{sub f{sub 2π}} = 0.56 has been used. We compare these values to previous measurements and theoretical predictions. (orig.)

  15. Response measurement of single-crystal chemical vapor deposition diamond radiation detector for intense X-rays aiming at neutron bang-time and neutron burn-history measurement on an inertial confinement fusion with fast ignition

    Energy Technology Data Exchange (ETDEWEB)

    Shimaoka, T., E-mail: t.shimaoka@eng.hokudai.ac.jp; Kaneko, J. H.; Tsubota, M. [Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Arikawa, Y.; Nagai, T.; Kojima, S.; Abe, Y.; Sakata, S.; Fujioka, S.; Nakai, M.; Shiraga, H.; Azechi, H. [Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Isobe, M. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Sato, Y. [The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Chayahara, A.; Umezawa, H.; Shikata, S. [Diamond Research Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

    2015-05-15

    A neutron bang time and burn history monitor in inertial confinement fusion with fast ignition are necessary for plasma diagnostics. In the FIREX project, however, no detector attained those capabilities because high-intensity X-rays accompanied fast electrons used for plasma heating. To solve this problem, single-crystal CVD diamond was grown and fabricated into a radiation detector. The detector, which had excellent charge transportation property, was tested to obtain a response function for intense X-rays. The applicability for neutron bang time and burn history monitor was verified experimentally. Charge collection efficiency of 99.5% ± 0.8% and 97.1% ± 1.4% for holes and electrons were obtained using 5.486 MeV alpha particles. The drift velocity at electric field which saturates charge collection efficiency was 1.1 ± 0.4 × 10{sup 7} cm/s and 1.0 ± 0.3 × 10{sup 7} cm/s for holes and electrons. Fast response of several ns pulse width for intense X-ray was obtained at the GEKKO XII experiment, which is sufficiently fast for ToF measurements to obtain a neutron signal separately from X-rays. Based on these results, we confirmed that the single-crystal CVD diamond detector obtained neutron signal with good S/N under ion temperature 0.5–1 keV and neutron yield of more than 10{sup 9} neutrons/shot.

  16. A database of neutron spectra, instrument response functions, and dosimetric conversion factors for radiation protection applications

    Energy Technology Data Exchange (ETDEWEB)

    Naismith, O.F. [National Physical Lab., Teddington (United Kingdom); Siebert, B.R.L. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    1997-09-01

    One of the major problems encountered in dose assessment for neutron radiation protection derives from the imperfect dose equivalent response of the devices used for monitoring. To investigate the performance of such devices in realistic neutron fields and to optimise calibration procedures, knowledge of both the prevalent spectral fluences and the energy response of the dosemeters is required. To facilitate this and similar studies, a database has been developed comprising a catalogue of neutron spectra and energy-dependent response functions together with a software package to manipulate the data in the catalogue. The range of data, features of the programs, and examples for radiation protection applications are described. (author).

  17. The Radiative Strength Function Using the Neutron-Capture Reaction on 151,153Eu

    Science.gov (United States)

    Agvaanluvsan, U.; Alpizar-Vicente, A.; Becker, J. A.; Bečvář, F.; Bredeweg, T. A.; Clement, R.; Esch, E.; Folden, C. M.; Hatarik, R.; Haight, R. C.; Hoffman, D. C.; Krtička, M.; Macri, R. A.; Mitchell, G. E.; Nitsche, H.; O'Donnell, J. M.; Parker, W.; Reifarth, R.; Rundberg, R. S.; Schwantes, J. M.; Sheets, S. A.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wilk, P.; Wouters, J. M.; Wu, C. Y.

    2006-03-01

    Radiative strength functions in 152,154Eu nuclei for γ-ray energies below 6 MeV have been investigated. Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for 151,153Eu targets. Properties of γ decay of neutron resonances in 152,154Eu nuclei are examined. The results of measurements are compared to outcome of simulation of γ cascades based on various models for the radiative strength function. Comparison between experimental data and simulation suggests existence of the low-energy resonance in these two nuclei.

  18. Neutron radiation effects on linear CCDs at different clock pulse frequency

    Directory of Open Access Journals (Sweden)

    Zujun Wang

    2015-06-01

    Full Text Available The experiments of reactor neutron radiation effects on linear CCDs are presented. The output voltage in dark field after neutron radiation are presented and compared at different clock pulse frequency. The degradation phenomena are analyzed in depth. The mean dark signal (KD and dark signal non-uniformity (DSNU versus neutron fluence is investigated at different clock pulse frequency. The degradation mechanisms of the dark signal and DSNU in linear CCDs are analyzed. The flux of the reactor neutron beams was about 1.33 × 108 n/cm2/s. The samples were exposed to 1MeV neutron-equivalent fluences of 1 × 1011, 5 × 1011, and 1 × 1012 n/cm2, respectively.

  19. Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system

    Science.gov (United States)

    Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

    2013-02-12

    A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

  20. Compounds for neutron radiation detectors and systems thereof

    Energy Technology Data Exchange (ETDEWEB)

    Payne, Stephen A.; Stoeffl, Wolfgang; Zaitseva, Natalia P.; Cherepy, Nerine J.; Carman, Leslie M.

    2016-08-30

    A composition of matter includes an organic molecule having a composition different than stilbene. The organic molecule is embodied as a crystal, and exhibits: an optical response signature for neutrons; an optical response signature for gamma rays, and performance comparable to or superior to stilbene in terms of distinguishing neutrons from gamma rays. The optical response signature for neutrons is different than the optical response signature for gamma rays.

  1. Compounds of 6Li and natural Li for EPR dosimetry in photon/neutron mixed radiation fields.

    Science.gov (United States)

    Lund, E; Gustafsson, H; Danilczuk, M; Sastry, M D; Lund, A

    2004-05-01

    Formates and dithionates of 6Li, enriched and 7Li in natural composition of Li offer a possibility to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field for instance at a boron neutron capture therapy (BNCT) facility. Tests with formates and dithionates of enriched 6Li and lithium compounds with natural composition have been performed at the BNCT facility at Studsvik, Sweden. Irradiations have been performed at 3 cm depth in a Perspex phantom in a fluence rate of thermal neutrons 1.8 x 10(9) n cm(-2) s(-1). The compounds were also irradiated in a pure X-ray field from a 4MV linear accelerator at 5 cm depth in a phantom with accurately determined absorbed doses. The signal intensity and shape was investigated within 3 h after the irradiation. A single line spectrum attributed to the CO2- radical was observed after irradiation of lithium formate. An increase in line width occurring after neutron irradiation in comparison with photon irradiation of the 6Li sample was attributed to dipolar broadening between CO2- radicals trapped in the tracks of the alpha particles. A spectrum due to the SO3- radical anion was observed after irradiation of lithium dithionate. The signal amplitude increased using the 6Li in place of the Li with natural composition of isotopes, in studies with low energy X-ray irradiation. Due to the decreased line width, caused by the difference in g(N) and I between the isotopes, the sensitivity with 6Li dithionate may be enhanced by an order of magnitude compared to alanine dosimetry. After comprehensive examination of the different combinations of compounds with different amounts of 6Li and 7Li regarding dosimetry, radiation chemistry and EPR properties these dosimeter material might be used for dose determinations at BNCT treatments and for biomedical experiments. Interesting properties of the radical formation might be visible due to the large difference in ionization density of neutrons compared to photons.

  2. Measurement of neutron dose equivalent to proton therapy patients outside of the proton radiation field

    CERN Document Server

    Yan, X; Köhler, A; Newhauser, W D

    2002-01-01

    Measurements of neutron dose equivalent values and neutron spectral fluences close to but outside of the therapeutic proton radiation field are presented. The neutron spectral fluences were determined at five locations with Bonner sphere measurements and established by unfolding techniques. More than 50 additional neutron dose equivalent values were measured with LiI and BF sub 3 thermal neutron detectors surrounded by a 25 cm polyethylene moderating sphere. For a large-field treatment, typical values of neutron dose equivalent per therapeutic proton absorbed dose, H/D, at 50 cm distance from isocenter, range from 1 mSv/Gy (at 0 deg.with respect to the proton beam axis) to 5 mSv/Gy (at 90 deg.). Experiments reveal that H/D varies significantly with the treatment technique, e.g., patient orientation, proton beam energy, and range-modulation. The relative uncertainty in H/D values is approximately 40% (one standard deviation).

  3. Detection of gamma-neutron radiation by solid-state scintillation detectors. Detection of gamma-neutron radiation by novel solid-state scintillation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ryzhikov, V.; Grinyov, B.; Piven, L.; Onyshchenko, G.; Sidletskiy, O. [Institute for Scintillation Materials of the NAS of Ukraine, Kharkov, (Ukraine); Naydenov, S. [Institute for Single Crystals of the National Academy of Sciences of Ukraine, Kharkov, (Ukraine); Pochet, T. [DETEC-Europe, Vannes (France); Smith, C. [Naval Postgraduate School, Monterey, CA (United States)

    2015-07-01

    It is known that solid-state scintillators can be used for detection of both gamma radiation and neutron flux. In the past, neutron detection efficiencies of such solid-state scintillators did not exceed 5-7%. At the same time it is known that the detection efficiency of the gamma-neutron radiation characteristic of nuclear fissionable materials is by an order of magnitude higher than the efficiency of detection of neutron fluxes alone. Thus, an important objective is the creation of detection systems that are both highly efficient in gamma-neutron detection and also capable of exhibiting high gamma suppression for use in the role of detection of neutron radiation. In this work, we present the results of our experimental and theoretical studies on the detection efficiency of fast neutrons from a {sup 239}Pu-Be source by the heavy oxide scintillators BGO, GSO, CWO and ZWO, as well as ZnSe(Te, O). The most probable mechanism of fast neutron interaction with nuclei of heavy oxide scintillators is the inelastic scattering (n, n'γ) reaction. In our work, fast neutron detection efficiencies were determined by the method of internal counting of gamma-quanta that emerge in the scintillator from (n, n''γ) reactions on scintillator nuclei with the resulting gamma energies of ∼20-300 keV. The measured efficiency of neutron detection for the scintillation crystals we considered was ∼40-50 %. The present work included a detailed analysis of detection efficiency as a function of detector and area of the working surface, as well as a search for new ways to create larger-sized detectors of lower cost. As a result of our studies, we have found an unusual dependence of fast neutron detection efficiency upon thickness of the oxide scintillators. An explanation for this anomaly may involve the competition of two factors that accompany inelastic scattering on the heavy atomic nuclei. The transformation of the energy spectrum of neutrons involved in the (n, n

  4. Damage Induced by Neutron Radiation on Output Characteristics of Solar Cells, Photodiodes, and Phototransistors

    Directory of Open Access Journals (Sweden)

    Biljana Simić

    2013-01-01

    Full Text Available This study investigates the effects of neutron radiation on I-V characteristics (current dependance on voltage of commercial optoelectronic devices (silicon photodiodes, phototransistors, and solar panels. Current-voltage characteristics of the samples were measured at room temperature before and after irradiation. The diodes were irradiated using Am-Be neutron source with neutron emission of 2.7×106 n/s. The results showed a decrease in photocurrent for all samples which could be due to the existence of neutron-induced displacement defects introduced into the semiconductor lattice. The process of annealing has also been observed. A comparative analysis of measurement results has been performed in order to determine the reliability of optoelectronic devices in radiation environments.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Thermal neutron radiative capture cross-section of 186W(n, γ)187W reaction

    Science.gov (United States)

    Tan, V. H.; Son, P. N.

    2016-06-01

    The thermal neutron radiative capture cross section for 186W(n, γ)187W reaction was measured by the activation method using the filtered neutron beam at the Dalat research reactor. An optimal composition of Si and Bi, in single crystal form, has been used as neutron filters to create the high-purity filtered neutron beam with Cadmium ratio of Rcd = 420 and peak energy En = 0.025 eV. The induced activities in the irradiated samples were measured by a high resolution HPGe digital gamma-ray spectrometer. The present result of cross section has been determined relatively to the reference value of the standard reaction 197Au(n, γ)198Au. The necessary correction factors for gamma-ray true coincidence summing, and thermal neutron self-shielding effects were taken into account in this experiment by Monte Carlo simulations.

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

    Science.gov (United States)

    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.

  8. LiCaAlF6 scintillators in neutron and gamma radiation fields

    Science.gov (United States)

    Viererbl, L.; Klupák, V.; Vinš, M.; Koleška, M.; Šoltés, J.; Yoshikawa, A.; Nikl, M.

    2016-09-01

    Intentionally doped LiCaAlF6 (LiCAF) single crystals are prospective scintillators, especially for thermal neutron detection through the 6Li(n,t)4He nuclear reaction. Four different LiCAF scintillator samples were tested in various neutron and gamma fields. Two of the tested samples were LiCAF:Eu and LiCAF:Eu,Na single crystals, and another two samples were made of LiCAF:Eu micro crystals dispersed in transparent rubber, with different rubber dimensions. All LiCAF samples contain lithium enriched to6Li. A plutonium-beryllium source was used as a neutron source. The neutron spectrum was modified by moderator and filter to get different ratios between thermal, epithermal and fast neutron fluence rates. The MCNP code was used for calculations of the fluence rates for different configurations. Radionuclides 137Cs and 60Co were applied as gamma radiation sources. The light signal from the scintillator was evaluated with a photomultiplier and a multichannel analyzer. The purpose of this work was to study the characteristics of LiCAF scintillators, especially the ability to discriminate signals from neutron and gamma radiation, which is the basic scintillator condition for neutron detection in mixed neutron-gamma radiation fields. Generally, the discrimination can be done by the pulse height and/or the pulse shape of the evaluated signals. Both methods can be used for a LiCAF scintillator. However, only the pulse height discrimination method is discussed in this paper. The possibility of fast neutron detection with LiCAF scintillators was also tested.

  9. Radiation Detection and Classification of Heavy Oxide Inorganic Scintillator Crystals for Detection of Fast Neutrons

    Science.gov (United States)

    2016-06-01

    and alkali-halide scintillators for potential use in neutron and gamma detection systems .” M.S. thesis, Dept. Physics , Naval Posgraduate School...DETECTION AND CLASSIFICATION OF HEAVY OXIDE INORGANIC SCINTILLATOR CRYSTALS FOR DETECTION OF FAST NEUTRONS by Jacob W. Capps June 2016 Thesis...DATE June 2016 3. REPORT TYPE AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE RADIATION DETECTION AND CLASSIFICATION OF HEAVY OXIDE

  10. Radiation injury of boron neutron capture therapy using mixed epithermal- and thermal neutron beams in patients with malignant glioma

    Energy Technology Data Exchange (ETDEWEB)

    Kageji, T. E-mail: kageji@clin.med.tokushima-u.ac.jp; Nagahiro, S.; Mizobuchi, Y.; Toi, H.; Nakagawa, Y.; Kumada, H

    2004-11-01

    The purpose of this study was to clarify the radiation injury in acute or delayed stage after boron neutron capture therapy (BNCT) using mixed epithermal- and thermal neutron beams in patients with malignant glioma. Eighteen patients with malignant glioma underwent mixed epithermal- and thermal neutron beam and sodium borocaptate between 1998 and 2004. The radiation dose (i.e. physical dose of boron n-alpha reaction) in the protocol used between 1998 and 2000 (Protocol A, n=8) prescribed a maximum tumor volume dose of 15 Gy. In 2001, a new dose-escalated protocol was introduced (Protocol B, n=4); it prescribes a minimum tumor volume dose of 18 Gy or, alternatively, a minimum target volume dose of 15 Gy. Since 2002, the radiation dose was reduced to 80-90% dose of Protocol B because of acute radiation injury. A new Protocol was applied to 6 glioblastoma patients (Protocol C, n=6). The average values of the maximum vascular dose of brain surface in Protocol A, B and C were 11.4{+-}4.2 Gy, 15.7{+-}1.2 and 13.9{+-}3.6 Gy, respectively. Acute radiation injury such as a generalized convulsion within 1 week after BNCT was recognized in three patients of Protocol B. Delayed radiation injury such as a neurological deterioration appeared 3-6 months after BNCT, and it was recognized in 1 patient in Protocol A, 5 patients in Protocol B. According to acute radiation injury, the maximum vascular dose was 15.8{+-}1.3 Gy in positive and was 12.6{+-}4.3 Gy in negative. There was no significant difference between them. According to the delayed radiation injury, the maximum vascular dose was 13.8{+-}3.8 Gy in positive and was 13.6{+-}4.9 Gy in negative. There was no significant difference between them. The dose escalation is limited because most patients in Protocol B suffered from acute radiation injury. We conclude that the maximum vascular dose does not exceed over 12 Gy to avoid the delayed radiation injury, especially, it should be limited under 10 Gy in the case that tumor

  11. Atmospheres and radiating surfaces of neutron stars with strong magnetic fields

    CERN Document Server

    Potekhin, A Y; Chabrier, G

    2016-01-01

    We review the current status of the theory of thermal emission from the surface layers of neutron stars with strong magnetic fields $B\\sim 10^{10}-10^{15}$ G, including formation of the spectrum in a partially ionized atmosphere and at a condensed surface. In particular, we describe recent progress in modeling partially ionized atmospheres of central compact objects in supernova remnants, which may have moderately strong fields $B\\sim 10^{10}-10^{11}$ G. Special attention is given to polarization of thermal radiation emitted by a neutron star surface. Finally, we briefly describe applications of the theory to observations of thermally emitting isolated neutron stars.

  12. System and plastic scintillator for discrimination of thermal neutron, fast neutron, and gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, Natalia P.; Carman, M. Leslie; Faust, Michelle A.; Glenn, Andrew M.; Martinez, H. Paul; Pawelczak, Iwona A.; Payne, Stephen A.

    2017-05-16

    A scintillator material according to one embodiment includes a polymer matrix; a primary dye in the polymer matrix, the primary dye being a fluorescent dye, the primary dye being present in an amount of 3 wt % or more; and at least one component in the polymer matrix, the component being selected from a group consisting of B, Li, Gd, a B-containing compound, a Li-containing compound and a Gd-containing compound, wherein the scintillator material exhibits an optical response signature for thermal neutrons that is different than an optical response signature for fast neutrons and gamma rays. A system according to one embodiment includes a scintillator material as disclosed herein and a photodetector for detecting the response of the material to fast neutron, thermal neutron and gamma ray irradiation.

  13. Calculation of isodose curves from initial neutron radiation of a hypothetical nuclear explosion using Monte Carlo Method

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, Marcos P.C.; Rebello, Wilson F.; Andrade, Edson R., E-mail: rebello@ime.eb.br, E-mail: daltongirao@yahoo.com.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Nuclear; Silva, Ademir X., E-mail: ademir@nuclear.ufrj.br [Corrdenacao dos Programas de Pos-Graduacao em Egenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2015-07-01

    Nuclear explosions are usually described in terms of its total yield and associated shock wave, thermal radiation and nuclear radiation effects. The nuclear radiation produced in such events has several components, consisting mainly of alpha and beta particles, neutrinos, X-rays, neutrons and gamma rays. For practical purposes, the radiation from a nuclear explosion is divided into {sup i}nitial nuclear radiation{sup ,} referring to what is issued within one minute after the detonation, and 'residual nuclear radiation' covering everything else. The initial nuclear radiation can also be split between 'instantaneous or 'prompt' radiation, which involves neutrons and gamma rays from fission and from interactions between neutrons and nuclei of surrounding materials, and 'delayed' radiation, comprising emissions from the decay of fission products and from interactions of neutrons with nuclei of the air. This work aims at presenting isodose curves calculations at ground level by Monte Carlo simulation, allowing risk assessment and consequences modeling in radiation protection context. The isodose curves are related to neutrons produced by the prompt nuclear radiation from a hypothetical nuclear explosion with a total yield of 20 KT. Neutron fluency and emission spectrum were based on data available in the literature. Doses were calculated in the form of ambient dose equivalent due to neutrons H*(10){sub n}{sup -}. (author)

  14. Historical Evaluation of Film Badge Dosimetry Y-12 Plant: Part 2–Neutron Radiation ORAUT-OTIB-0045

    Energy Technology Data Exchange (ETDEWEB)

    Kerr GD, Frome EL, Watkins JP, Tankersley WG

    2009-12-14

    A summary of the major neutron sources involved in radiation exposures to Y-12 workers is presented in this TIB. Graphical methods are used to evaluate available neutron dose data from quarterly exposures to Y-12 workers and to determine how the data could be used to derive neutron-to-gamma dose ratios for dose reconstruction purposes. This TIB provides estimates of neutron-to-gamma dose ratios for specific departments and a default value for the neutron-to-gamma dose ratio based on the pooled neutron dose data for all Y-12 departments.

  15. The Radiative Strength Function Using the Neutron-Capture Reaction on 151,153Eu

    Energy Technology Data Exchange (ETDEWEB)

    Agvaanluvsan, U; Alpizar-Vicente, A; Becker, J A; Becvar, F; Bredeweg, T A; Clement, R; Esch, E; Folden, C M; Hatarik, R; Haight, R C; Hoffman, D C; Krticka, M; Macri, R A; Mitchell, G E; Nitsche, H; O' Donnell, J M; Parker, W; Reifarth, R; Rundberg, R S; Schwantes, J M; Sheets, S A; Ullmann, J L; Vieira, D J; Wilhelmy, J B; Wilk, P; Wouters, J M; Wu, C Y

    2005-10-04

    Radiative strength functions in {sup 152,154}Eu nuclei for {gamma}-ray energies below 6 MeV have been investigated. Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for {sup 151,153}Eu targets. Properties of resonances in these two nuclei are examined. The measurements are compared to simulation of cascades performed with various models for the radiative strength function. Comparison between experimental data and simulation suggests an existence of the low-energy resonance in these two nuclei.

  16. Advances in nuclear particle dosimetry for radiation protection and medicine - Ninth Symposium on Neutron Dosimetry (Editorial Material, English)

    Energy Technology Data Exchange (ETDEWEB)

    Zoetelief, J; Bos, A J.; Schuhmacher, H; McDonald, Joseph C.; Schultz, F W.; Pihet, P

    2004-12-15

    The Ninth Symposium on Neutron Dosimetry has been expanded to cover not only neutron radiation but heavy charged particle dosimetry as well. The applications are found in such fields as radiation protection, aircrew dosimetry, medicine, nuclear power and accelerator health physics. Scientists from many countries from around the world presented their work, and described the latest developments in techniques and instrumentation.

  17. Measurement of gamma and neutron radiations inside spent fuel assemblies with passive detectors

    Energy Technology Data Exchange (ETDEWEB)

    Viererbl, L., E-mail: vie@ujv.cz [Nuclear Research Institute Rez plc, 250 68 Husinec-Rez 130 (Czech Republic); Research Centre Rez Ltd. (Czech Republic); Lahodova, Z.; Voljanskij, A.; Klupak, V.; Koleska, M. [Nuclear Research Institute Rez plc, 250 68 Husinec-Rez 130 (Czech Republic); Research Centre Rez Ltd. (Czech Republic); Cabalka, M. [Nuclear Research Institute Rez plc, 250 68 Husinec-Rez 130 (Czech Republic); Turek, K. [Nuclear Physics Institute, Academy of Sciences of the Czech Republic (Czech Republic)

    2011-10-01

    During operation of a fission nuclear reactor, many radionuclides are generated in fuel by fission and activation of {sup 235}U, {sup 238}U and other nuclides present in the assembly. After removal of a fuel assembly from the core, these radionuclides are sources of different types of radiation. Gamma and neutron radiation emitted from an assembly can be non-destructively detected with different types of detectors. In this paper, a new method of measurement of radiation from a spent fuel assembly is presented. It is based on usage of passive detectors, such as alanine dosimeters for gamma radiation and track detectors for neutron radiation. Measurements are made on the IRT-2M spent fuel assemblies used in the LVR-15 research reactor. During irradiation of detectors, the fuel assembly is located in a water storage pool at a depth of 6 m. Detectors are inserted into central hole of the assembly, irradiated for a defined time interval, and after the detectors removed from the assembly, gamma dose or neutron fluence are evaluated. Measured profiles of gamma dose rate and neutron fluence rate inside of the spent fuel assembly are presented. This measurement can be used to evaluate relative fuel burn-up.

  18. Measurement of gamma and neutron radiations inside spent fuel assemblies with passive detectors

    Science.gov (United States)

    Viererbl, L.; Lahodová, Z.; Voljanskij, A.; Klupák, V.; Koleška, M.; Cabalka, M.; Turek, K.

    2011-10-01

    During operation of a fission nuclear reactor, many radionuclides are generated in fuel by fission and activation of 235U, 238U and other nuclides present in the assembly. After removal of a fuel assembly from the core, these radionuclides are sources of different types of radiation. Gamma and neutron radiation emitted from an assembly can be non-destructively detected with different types of detectors. In this paper, a new method of measurement of radiation from a spent fuel assembly is presented. It is based on usage of passive detectors, such as alanine dosimeters for gamma radiation and track detectors for neutron radiation. Measurements are made on the IRT-2M spent fuel assemblies used in the LVR-15 research reactor. During irradiation of detectors, the fuel assembly is located in a water storage pool at a depth of 6 m. Detectors are inserted into central hole of the assembly, irradiated for a defined time interval, and after the detectors removed from the assembly, gamma dose or neutron fluence are evaluated. Measured profiles of gamma dose rate and neutron fluence rate inside of the spent fuel assembly are presented. This measurement can be used to evaluate relative fuel burn-up.

  19. Contribution of Neutron Beta Decay to Radiation Belt Pumping from High Altitude Nuclear Explosion

    Energy Technology Data Exchange (ETDEWEB)

    Marrs, R

    2002-11-13

    In 1962, several satellites were lost following high altitude nuclear tests by the United States and the Soviet Union. These satellite failures were caused by energetic electrons injected into the earth's radiation belts from the beta decay of bomb produced fission fragments and neutrons. It has been 40 years since the last high altitude nuclear test; there are now many more satellites in orbit, and it is important to understand their vulnerability to radiation belt pumping from nuclear explosions at high altitude or in space. This report presents the results of a calculation of the contribution of neutron beta decay to artificial belt pumping. For most high altitude nuclear explosions, neutrons are expected to make a smaller contribution than fission products to the total trapped electron inventory, and their contribution is usually neglected. However, the neutron contribution may dominate in cases where the fission product contribution is suppressed due to the altitude or geomagnetic latitude of the nuclear explosion, and for regions of the radiation belts with field lines far from the detonation point. In any case, an accurate model of belt pumping from high altitude nuclear explosions, and a self-consistent explanation of the 1962 data, require inclusion of the neutron contribution. One recent analysis of satellite measurements of electron flux from the 1962 tests found that a better fit to the data is obtained if the neutron contribution to the trapped electron inventory was larger than that of the fission products [l]. Belt pumping from high altitude nuclear explosions is a complicated process. Fission fragments are dispersed as part of the ionized bomb debris, which is constrained and guided by the earth's magnetic field. Those fission products that beta decay before being lost to the earth's atmosphere can contribute trapped energetic electrons to the earth's radiation belts. There has been a large effort to develop computer models for

  20. Materials for Low-Energy Neutron Radiation Shielding

    Science.gov (United States)

    Singleterry, Robert C., Jr.; Thibeault, Sheila A.

    2000-01-01

    Various candidate aircraft and spacecraft materials were analyzed and compared in a low-energy neutron environment using the Monte Carlo N-Particle (MCNP) transport code with an energy range up to 20 MeV. Some candidate materials have been tested in particle beams, and others seemed reasonable to analyze in this manner before deciding to test them. The two metal alloys analyzed are actual materials being designed into or used in aircraft and spacecraft today. This analysis shows that hydrogen-bearing materials have the best shielding characteristics over the metal alloys. It also shows that neutrons above 1 MeV are reflected out of the face of the slab better by larger quantities of carbon in the material. If a low-energy absorber is added to the material, fewer neutrons are transmitted through the material. Future analyses should focus on combinations of scatterers and absorbers to optimize these reaction channels and on the higher energy neutron component (above 50 MeV).

  1. Neutron radiation effect on 4H-SiC MESFETs and SBDs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lin; Zhang Yimen; Zhang Yuming; Han Chao, E-mail: zhanglin@mail.xidian.edu.cn [Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China)

    2010-11-15

    4H-SiC metal Schottky field effect transistors (MESFETs) and Schottky barrier diodes (SBDs) were irradiated at room temperature with 1 MeV neutrons. The highest neutron flux and gamma-ray total dose were 1 x 10{sup 15} n/cm{sup 2} and 3.3 Mrad(Si), respectively. After a neutron flux of 1 x 10{sup 13} n/cm{sup 2}, the current characteristics of the MESFET had only slightly changed, and the Schottky contacts of the gate contacts and the Ni, Ti/4H-SiC SBDs showed no obvious degradation. To further increase the neutron flux, the drain current of the SiC MESFET decreased and the threshold voltage increased. {phi}{sub B} of the Schottky gate contact decreased when the neutron flux was more than or equal to 2.5 x 10{sup 14} n/cm{sup 2}. SiC Schottky interface damage and radiation defects in the bulk material are mainly mechanisms for performance degradation of the experiment devices, and a high doping concentration of the active region will improve the neutron radiation tolerance.

  2. Fast Scintillation Probes For Investigation Of Pulsed Neutron Radiation From Small Fusion Devices

    Science.gov (United States)

    Tomaszewski, Krzysztof J.

    2008-04-01

    This paper presents the design as well as laboratory/performance tests results taken by means of the fast scintillation probes. The design of each scintillation probe is based on photomultiplier tube hybrid assembly, which—besides photomultiplier itself—also includes high-voltage divider optimized for recording of fast radiation bursts. Plastic scintillators with short-time response are applied as hard X-ray and neutron radiation detectors. Heavy-duty probe's housing provides efficient shielding against electromagnetic interference and allows carrying out pulsed neutron measurements in a harsh electromagnetic environment. The crucial parameters of scintillation probes have been examined during laboratory tests in which our investigations have been aimed mainly to determine: a time response, an anode radiant sensitivity and an electron transit time dependence on high-voltage supply. During the performance tests, the relative calibration of probes set has been done. It allowed to carry out very accurate measurements of neutron emission anisotropy and investigations of neutron radiation scattering by different materials. The usefulness of presented scintillation probes—embedded in the neutron time-of-flight diagnostic system was proven during experimental campaigns conducted on the plasma-focus PF1000 device.

  3. Neutron radiation shielding properties of polymer incorporated self compacting concrete mixes.

    Science.gov (United States)

    Malkapur, Santhosh M; Divakar, L; Narasimhan, Mattur C; Karkera, Narayana B; Goverdhan, P; Sathian, V; Prasad, N K

    2017-07-01

    In this work, the neutron radiation shielding characteristics of a class of novel polymer-incorporated self-compacting concrete (PISCC) mixes are evaluated. Pulverized high density polyethylene (HDPE) material was used, at three different reference volumes, as a partial replacement to river sand in conventional concrete mixes. By such partial replacement of sand with polymer, additional hydrogen contents are incorporated in these concrete mixes and their effect on the neutron radiation shielding properties are studied. It has been observed from the initial set of experiments that there is a definite trend of reductions in the neutron flux and dose transmission factor values in these PISCC mixes vis-à-vis ordinary concrete mix. Also, the fact that quite similar enhanced shielding results are recorded even when reprocessed HDPE material is used in lieu of the virgin HDPE attracts further attention. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Model-Independent Calculation of Radiative Neutron Capture on Lithium-7

    NARCIS (Netherlands)

    Rupak, Gautam; Higa, Renato

    2011-01-01

    The radiative neutron capture on lithium-7 is calculated model independently using a low-energy halo effective field theory. The cross section is expressed in terms of scattering parameters directly related to the S-matrix elements. It depends on the poorly known p-wave effective range parameter r(1

  5. Fast neutron radiation induced Glu-B1 deficient lines of an elite bread wheat variety

    Science.gov (United States)

    Five isogenic wheat lines deficient in high-molecular weight subunit (HMW-GS) proteins encoded by the B-genome were identified from a fast-neutron radiation-mutagenized population of Summit, an elite variety of bread wheat (Triticum aestivum L.). The mutant lines differ from the wild-type progenit...

  6. A comprehensive spectrometry study of a stray neutron radiation field in scanning proton therapy

    Science.gov (United States)

    Mares, Vladimir; Romero-Expósito, Maite; Farah, Jad; Trinkl, Sebastian; Domingo, Carles; Dommert, Martin; Stolarczyk, Liliana; Van Ryckeghem, Laurent; Wielunski, Marek; Olko, Pawel; Harrison, Roger M.

    2016-06-01

    The purpose of this study is to characterize the stray neutron radiation field in scanning proton therapy considering a pediatric anthropomorphic phantom and a clinically-relevant beam condition. Using two extended-range Bonner sphere spectrometry systems (ERBSS), Working Group 9 of the European Radiation Dosimetry Group measured neutron spectra at ten different positions around a pediatric anthropomorphic phantom irradiated for a brain tumor with a scanning proton beam. This study compares the different systems and unfolding codes as well as neutron spectra measured in similar conditions around a water tank phantom. The ten spectra measured with two ERBSS systems show a generally similar thermal component regardless of the position around the phantom while high energy neutrons (above 20 MeV) were only registered at positions near the beam axis (at 0°, 329° and 355°). Neutron spectra, fluence and ambient dose equivalent, H *(10), values of both systems were in good agreement (<15%) while the unfolding code proved to have a limited effect. The highest H *(10) value of 2.7 μSv Gy-1 was measured at 329° to the beam axis and 1.63 m from the isocenter where high-energy neutrons (E  ⩾  20 MeV) contribute with about 53%. The neutron mapping within the gantry room showed that H *(10) values significantly decreased with distance and angular position with respect to the beam axis dropping to 0.52 μSv Gy-1 at 90° and 3.35 m. Spectra at angles of 45° and 135° with respect to the beam axis measured here with an anthropomorphic phantom showed a similar peak structure at the thermal, fast and high energy range as in the previous water-tank experiments. Meanwhile, at 90°, small differences at the high-energy range were observed. Using ERBSS systems, neutron spectra mapping was performed to characterize the exposure of scanning proton therapy patients. The ten measured spectra provide precise information about the exposure of healthy organs to thermal

  7. The effect of electrons, neutron and gamma radiation on nitrocellulose; Effet des radiations gamma, des electrons et des neutrons sur la nitrocellulose

    Energy Technology Data Exchange (ETDEWEB)

    Heppell-Masys, K.M. [College Militaire Royal du Canada, Dept. de chimie et genie chimique, Kingston, Ontario (Canada)

    2001-07-01

    High nitrogen content nitrocellulose is mostly used as an explosive component in the fabrication of propellant. Slow evaporation of the stabiliser agents deteriorate the safe properties of these materials throughout the years, making them hazardous to handle well beyond their shelf lives. The irradiation may neutralize and convert the stocks of aged and unstable nitrocellulose explosives into less nitrated hence non-explosive substance. The effects of electrons, thermal neutrons and gamma radiation on the nitrogen content of wet nitrocellulose using the SLOWPOKE-2 nuclear reactor were investigated. Four nitrocellulose grades containing 30% water were used:12.11% N,12.60% N, 13.11% N and 13.22% N. These samples of about 0.3g each contained in sealed polyethylene vials were exposed to thermal neutrons, gamma and electron radiation in the SLOWPOKE-2 reactor pool for various times ranging from 15 minutes to 10 hours. In order to assess the extent of change in the nitrogen content, solutions of nitrocellulose in tetrahydrofuran were analyzed using Gel Permeation Chromatography (GPC) and Fourier Transform Infrared Spectroscopy (FTIR). A decrease of molecular weights and numbers was observed from GPC results as well as an increase of polydispersity indicating chain scission of the nitrocellulose backbone. The G value indicated that scission yield was predominant over the crosslinking yield. Nitrocellulose exposure to thermal neutrons, gamma rays and electrons is indeed effective in reducing average molecular weight and number, as well as in decreasing nitrogen content.

  8. Development and characterization of the integrated fiber-optic radiation sensor for the simultaneous detection of neutrons and gamma rays.

    Science.gov (United States)

    Jang, Kyoung Won; Lee, Bong Soo; Moon, Joo Hyun

    2011-04-01

    Sometimes, detection of thermal neutrons in the presence of gamma rays is required. This study developed and characterized an integrated fiber-optic radiation sensor for the simultaneous detection of thermal neutrons and gamma rays in a mixed radiation field. The performance of the integrated sensor was verified by measuring the distributions of thermal neutrons and gamma rays released from a nuclear fuel rod at the Kyoto University Critical Assembly. The experimental results show that the integrated sensor produced similar distribution patterns to those of thermal neutrons and gamma rays released from a fuel rod.

  9. Precision tests of the J/psi from full lattice QCD: mass, leptonic width and radiative decay rate to eta_c

    CERN Document Server

    Davies, C T H; Dowdall, R J; Koponen, J; Follana, E; Hornbostel, K; Lepage, G P; McNeile, C

    2013-01-01

    We show results from calculations in full lattice QCD of the mass, leptonic width and radiative decay rate to eta_c of the J/psi meson. These provide few % tests of QCD. Another (1.5%) test comes from comparison of time-moments of the vector charmonium correlator with results derived from the experimental values of R(e+e- to hadrons) in the charm region.

  10. Neutron measurements with Time-Resolved Event-Counting Optical Radiation (TRECOR) detector

    Science.gov (United States)

    Brandis, M.; Vartsky, D.; Dangendorf, V.; Bromberger, B.; Bar, D.; Goldberg, M. B.; Tittelmeier, K.; Friedman, E.; Czasch, A.; Mardor, I.; Mor, I.; Weierganz, M.

    2012-04-01

    Results are presented from the latest experiment with a new neutron/gamma detector, a Time-Resolved, Event-Counting Optical Radiation (TRECOR) detector. It is composed of a scintillating fiber-screen converter, bending mirror, lens and Event-Counting Image Intensifier (ECII), capable of specifying the position and time-of-flight of each event. TRECOR is designated for a multipurpose integrated system that will detect Special Nuclear Materials (SNM) and explosives in cargo. Explosives are detected by Fast-Neutron Resonance Radiography, and SNM by Dual Discrete-Energy gamma-Radiography. Neutrons and gamma-rays are both produced in the 11B(d,n+γ)12C reaction. The two detection modes can be implemented simultaneously in TRECOR, using two adjacent radiation converters that share a common optical readout. In the present experiment the neutron detection mode was studied, using a plastic scintillator converter. The measurements were performed at the PTB cyclotron, using the 9Be(d,n) neutron spectrum obtained from a thick Be-target at Ed ~ 13 MeV\\@. The basic characteristics of this detector were investigated, including the Contrast Transfer Function (CTF), Point Spread Function (PSF) and elemental discrimination capability.

  11. Early ultrastructural changes in the rat adenohypophysis following exposure to neutron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Teshchenko, G.A.; Monastyrskaya, B.I.

    1977-01-01

    An electron microscopic study was made of the rat adenohypophysis following single exposure to whole-body radiation (LD/sub 30/30/) with fast neutrons in the biochannel of the BBP-M reactor. The demonstrated intensification of corticotrophic and thyrotrophic elements, as well as depression of activity of somatotrophic ones, are analogous the previous findings following single whole-body x-irradiation of rats in an equivalent dosage, but more marked. The appearance of dark cells of the thyrotropic and somatotropic types is related to the direct effect of neutrons on this gland's cells.

  12. Reverse Monte Carlo studies of CeO2 using neutron and synchrotron radiation techniques

    Science.gov (United States)

    Clark, Adam H.; Marchbank, Huw R.; Hyde, Timothy I.; Playford, Helen Y.; Tucker, Matthew G.; Sankar, Gopinathan

    2017-03-01

    A reverse Monte Carlo analysis method was employed to extract the structure of CeO2 from Neutron total scattering (comprising both neutron diffraction (ND) and pair-distribution functions (PDF) and Ce L3- and K-edge EXAFS data. Here it is shown that there is a noticeable difference between using short ranged x-ray absorption spectroscopy data and using medium-long range PDF and ND data in regards to the disorder of the cerium atoms. This illustrates the importance of considering multiple length scales and radiation sources.

  13. Spatial and energy distributions of skyshine neutron and gamma radiation from nuclear reactors on the ground-air boundary

    Energy Technology Data Exchange (ETDEWEB)

    Orlov, Y.; Netecha, M.E.; Vasiliev, A.P.; Avaev, V.N.; Vasiliev, G.A. [Research and Development Institute of Power Engineering, Moscow (Russian Federation); Zelensky, D.I.; Istomin, Y.L.; Cherepnin, Y.S. [Institute of Atomic Energy of the National Nuclear Center of the Republic of Kazakhstan, Semipalatinsk-21 (Kazakhstan); Nomura, Y. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2000-03-01

    A set of measurements on skyshine radiation was conducted at two special research reactors. A broad range of detectors was used in the measurements to record neutron and gamma radiations. Dosimetric and radiometric field measurements of the neutrons and gamma quanta of the radiation scattered in the air were performed at distances of 50 to 1000 m from the reactor during different weather conditions. The neutron spectra in the energy range of 1 eV to 10 MeV and the gamma quanta spectra in the range of 0.1-10 MeV were measured. (author)

  14. Analysis for Radiation and Shielding Dose in Plasma Focus Neutron Source Using FLUKA

    Science.gov (United States)

    Nemati, M. J.; Amrollahi, R.; Habibi, M.

    2012-06-01

    Monte Carlo simulations have been performed for the attenuation of neutron radiation produced at Plasma focus (PF) devices through various shielding design. At the test site it will be fired with deuterium and tritium (D-T) fusion resulting in a yield of about 1013 fusion neutrons of 14 MeV. This poses a radiological hazard to scientists and personnel operating the device. The goal of this paper was to evaluate various shielding options under consideration for the PF operating with D-T fusion. Shields of varying neutrons-shielding effectiveness were investigated using concrete, polyethylene, paraffin and borated materials. The most effective shield, a labyrinth structure, allowed almost 1,176 shots per year while keeping personnel under 20 mSV of dose. The most expensive shield that used, square shield with 100 cm concrete thickness on the walls and Borated paraffin along with borated polyethylene added outside the concrete allowed almost 15,000 shot per year.

  15. Review of measurement techniques for the neutron radiative-capture process

    Energy Technology Data Exchange (ETDEWEB)

    Poenitz, W.P.

    1981-07-01

    The experimental techniques applied in measurements of the neutron capture process are reviewed. The emphasis is on measurement techniques used in neutron capture cross section measurements. The activation technique applied mainly in earlier work has still its use in some cases, specifically for measurements of technologically important cross sections (/sup 238/U and /sup 232/Th) with high accuracy. Three major prompt neutron radioactive capture detection techniques have evolved: the total gamma radiation energy detection technique (mainly with large liquid scintillation detectors), the gamma-energy proportional detectors (with proportional counters or Moxon-Rae detectors), and the pulse-height weighting technique. These measurement techniques are generally applicable, however, shortcomings limit the achievable accuracy to a approx. = 5 to 15% uncertainty level.

  16. Secondary Neutron Production from Space Radiation Interactions: Advances in Model and Experimental Data Base Development

    Science.gov (United States)

    Heilbronn, Lawrence H.; Townsend, Lawrence W.; Braley, G. Scott; Iwata, Yoshiyuki; Iwase, Hiroshi; Nakamura, Takashi; Ronningen, Reginald M.; Cucinotta, Francis A.

    2003-01-01

    For humans engaged in long-duration missions in deep space or near-Earth orbit, the risk from exposure to galactic and solar cosmic rays is an important factor in the design of spacecraft, spacesuits, and planetary bases. As cosmic rays are transported through shielding materials and human tissue components, a secondary radiation field is produced. Neutrons are an important component of that secondary field, especially in thickly-shielded environments. Calculations predict that 50% of the dose-equivalent in a lunar or Martian base comes from neutrons, and a recent workshop held at the Johnson Space Center concluded that as much as 30% of the dose in the International Space Station may come from secondary neutrons. Accelerator facilities provide a means for measuring the effectiveness of various materials in their ability to limit neutron production, using beams and energies that are present in cosmic radiation. The nearly limitless range of beams, energies, and target materials that are present in space, however, means that accelerator-based experiments will not provide a complete database of cross sections and thick-target yields that are necessary to plan and design long-duration missions. As such, accurate nuclear models of neutron production are needed, as well as data sets that can be used to compare with, and verify, the predictions from such models. Improvements in a model of secondary neutron production from heavy-ion interactions are presented here, along with the results from recent accelerator-based measurements of neutron-production cross sections. An analytical knockout-ablation model capable of predicting neutron production from high-energy hadron-hadron interactions (both nucleon-nucleus and nucleus-nucleus collisions) has been previously developed. In the knockout stage, the collision between two nuclei result in the emission of one or more nucleons from the projectile and/or target. The resulting projectile and target remnants, referred to as

  17. Secondary Neutron Production from Space Radiation Interactions: Advances in Model and Experimental Data Base Development

    Science.gov (United States)

    Heilbronn, Lawrence H.; Townsend, Lawrence W.; Braley, G. Scott; Iwata, Yoshiyuki; Iwase, Hiroshi; Nakamura, Takashi; Ronningen, Reginald M.; Cucinotta, Francis A.

    2003-01-01

    For humans engaged in long-duration missions in deep space or near-Earth orbit, the risk from exposure to galactic and solar cosmic rays is an important factor in the design of spacecraft, spacesuits, and planetary bases. As cosmic rays are transported through shielding materials and human tissue components, a secondary radiation field is produced. Neutrons are an important component of that secondary field, especially in thickly-shielded environments. Calculations predict that 50% of the dose-equivalent in a lunar or Martian base comes from neutrons, and a recent workshop held at the Johnson Space Center concluded that as much as 30% of the dose in the International Space Station may come from secondary neutrons. Accelerator facilities provide a means for measuring the effectiveness of various materials in their ability to limit neutron production, using beams and energies that are present in cosmic radiation. The nearly limitless range of beams, energies, and target materials that are present in space, however, means that accelerator-based experiments will not provide a complete database of cross sections and thick-target yields that are necessary to plan and design long-duration missions. As such, accurate nuclear models of neutron production are needed, as well as data sets that can be used to compare with, and verify, the predictions from such models. Improvements in a model of secondary neutron production from heavy-ion interactions are presented here, along with the results from recent accelerator-based measurements of neutron-production cross sections. An analytical knockout-ablation model capable of predicting neutron production from high-energy hadron-hadron interactions (both nucleon-nucleus and nucleus-nucleus collisions) has been previously developed. In the knockout stage, the collision between two nuclei result in the emission of one or more nucleons from the projectile and/or target. The resulting projectile and target remnants, referred to as

  18. Radiation Hardness tests with neutron flux on different Silicon photomultiplier devices

    Science.gov (United States)

    Cattaneo, P. W.; Cervi, T.; Menegolli, A.; Oddone, M.; Prata, M.; Prata, M. C.; Rossella, M.

    2017-07-01

    Radiation hardness is an important requirement for solid state readout devices operating in high radiation environments common in particle physics experiments. The MEG II experiment, at PSI, Switzerland, investigates the forbidden decay μ+ → e+ γ. Exploiting the most intense muon beam of the world. A significant flux of non-thermal neutrons (kinetic energy Ek>= 0.5 MeV) is present in the experimental hall produced along the beam-line and in the hall itself. We present the effects of neutron fluxes comparable to the MEG II expected doses on several Silicon Photomultiplier (SiPMs). The tested models are: AdvanSiD ASD-NUV3S-P50 (used in MEG II experiment), AdvanSiD ASD-NUV3S-P40, AdvanSiD ASD-RGB3S-P40, Hamamatsu and Excelitas C30742-33-050-X. The neutron source is the thermal Sub-critical Multiplication complex (SM1) moderated with water, located at the University of Pavia (Italy). We report the change of SiPMs most important electric parameters: dark current, dark pulse frequency, gain, direct bias resistance, as a function of the integrated neutron fluency.

  19. Radiation hardness tests of piezoelectric actuators with fast neutrons at liquid helium temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fouaidy, M.; Martinet, G.; Hammoudi, N.; Chatelet, F.; Olivier, A.; Blivet, S.; Galet, F. [CNRS-IN2P3-IPN Orsay, Orsay (France)

    2007-07-01

    Piezoelectric actuators, which are integrated into the cold tuning system and used to compensate the small mechanical deformations of the cavity wall induced by Lorentz forces due to the high electromagnetic surface field, may be located in the radiation environment during particle accelerator operation. In order to provide for a reliable operation of the accelerator, the performance and life time of piezoelectric actuators ({approx}24.000 units for ILC) should not show any significant degradation for long periods (i.e. machine life duration: {approx}20 years), even when subjected to intense radiation (i.e. gamma rays and fast neutrons). An experimental program, aimed at investigating the effect of fast neutrons radiation on the characteristics of piezoelectric actuators at liquid helium temperature (i.e. T{approx}4.2 K), was proposed for the working package WPNo.8 devoted to tuners development in the frame of CARE project. A neutrons irradiation facility, already installed at the CERI cyclotron located at Orleans (France), was upgraded and adapted for actuators irradiations tests purpose. A deuterons beam (maximum energy and beam current: 25 MeV and 35{mu}A) collides with a thin (thickness: 3 mm) beryllium target producing a high neutrons flux with low gamma dose ({approx}20%): a neutrons fluence of more than 10{sup 14} n/cm{sup 2} is achieved in {approx}20 hours of exposure. A dedicated cryostat was developed at IPN Orsay and used previously for radiation hardness test of calibrated cryogenic thermometers and pressure transducers used in LHC superconducting magnets. This cryostat could be operated either with liquid helium or liquid argon. This irradiation facility was upgraded for allowing fast turn-over of experiments and a dedicated experimental set-up was designed, fabricated, installed at CERI and successfully operated for radiation hardness tests of several piezoelectric actuators at T{approx}4.2 K. This new apparatus allows on-line automatic measurements

  20. Gravitational radiation from neutron stars deformed by crustal Hall drift

    Science.gov (United States)

    Suvorov, A. G.; Mastrano, A.; Geppert, U.

    2016-07-01

    A precondition for the radio emission of pulsars is the existence of strong, small-scale magnetic field structures (`magnetic spots') in the polar cap region. Their creation can proceed via crustal Hall drift out of two qualitatively and quantitatively different initial magnetic field configurations: a field confined completely to the crust and another which penetrates the whole star. The aim of this study is to explore whether these magnetic structures in the crust can deform the star sufficiently to make it an observable source of gravitational waves. We model the evolution of these field configurations, which can develop, within ˜104-105 yr, magnetic spots with local surface field strengths ˜1014 G maintained over ≳106 yr. Deformations caused by the magnetic forces are calculated. We show that, under favourable initial conditions, a star undergoing crustal Hall drift can have ellipticity ɛ ˜ 10-6, even with sub-magnetar polar field strengths, after ˜105 yr. A pulsar rotating at ˜102 Hz with such ɛ is a promising gravitational wave source candidate. Since such large deformations can be caused only by a particular magnetic field configuration that penetrates the whole star and whose maximum magnetic energy is concentrated in the outer core region, gravitational wave emission observed from radio pulsars can thus inform us about the internal field structures of young neutron stars.

  1. Modeling the Spin Equilibrium of Neutron Stars in LMXBs Without Gravitational Radiation

    Science.gov (United States)

    Andersson, N.; Glampedakis, K.; Haskell, B.; Watts, A. L.

    2004-01-01

    In this paper we discuss the spin-equilibrium of accreting neutron stars in LMXBs. We demonstrate that, when combined with a naive spin-up torque, the observed data leads to inferred magnetic fields which are at variance with those of galactic millisecond radiopulsars. This indicates the need for either additional spin-down torques (eg. gravitational radiation) or an improved accretion model. We show that a simple consistent accretion model can be arrived at by accounting for radiation pressure in rapidly accreting systems (above a few percent of the Eddington accretion rate). In our model the inner disk region is thick and significantly sub-Keplerian, and the estimated equilibrium periods are such that the LMXB neutron stars have properties that accord well with the galactic millisecond radiopulsar sample. The implications for future gravitational-wave observations are also discussed briefly.

  2. Investigating Time and Spectral Dependence in Neutron Radiation Environments for Semiconductor Damage Studies

    Science.gov (United States)

    2014-09-18

    source of beta particles with radius , s, a distance, d, away from a detector with radius , a. The geometric factor, ξ, is dependent on the solid angle...parameters varied in sensitivity study. Units of D are cm2/s, units of E are eV, units of ν are s−1 and units of Radius are Å...as much of the neutron radiation (either cosmic or nuclear weapon induced) remains hard and the radiation pulse short. Also, the gamma flux from

  3. Comparison of radiation damage in silicon induced by proton and neutron irradiation

    CERN Document Server

    Ruzin, A; Glaser, M; Zanet, A; Lemeilleur, F; Watts, S

    1999-01-01

    The subject of radiation damage to Si detectors induced by 24-GeV/c protons and nuclear reactor neutrons has been studied. Detectors fabricated on single-crystal silicon enriched with various impurities have been tested. Significant differences in electrically active defects have been found between the various types of material. The results of the study suggest for the first time that the widely used nonionizing energy loss (NIEL) factors are insufficient for normalization of the electrically active damage in case of oxygen- and carbon-enriched silicon detectors. It has been found that a deliberate introduction of impurities into the semiconductor can affect the radiation hardness of silicon detectors. (16 refs).

  4. Importance of Compton scattering for radiation spectra of isolated neutron stars with weak magnetic fields

    CERN Document Server

    Suleimanov, V

    2007-01-01

    Emergent model spectra of neutron star atmospheres are widely used to fit the observed soft X-ray spectra of different types of isolated neutron stars. We investigate the effect of Compton scattering on the emergent spectra of hot (T_eff > 10^6 K) isolated neutron stars with weak magnetic fields. In order to compute model atmospheres in hydrostatic and radiative equilibrium we solve the radiation transfer equation with the Kompaneets operator. We calculate a set of models with effective temperatures in the range 1 - 5 * 10^6 K, with two values of surface gravity (log g = 13.9 and 14.3) and different chemical compositions. Radiation spectra computed with Compton scattering are softer than those computed without Compton scattering at high energies (E > 5 keV) for light elements (H or He) model atmospheres. The Compton effect is more significant in H model atmospheres and models with low surface gravity. The emergent spectra of the hottest (T_eff > 3 * 10^6 K) model atmospheres can be described by diluted blackb...

  5. Saturn Neutron Exosphere as Source for Inner and Innermost Radiation Belts

    Science.gov (United States)

    Cooper, John; Lipatov, Alexander; Sittler, Edward; Sturner, Steven

    2011-01-01

    Energetic proton and electron measurements by the ongoing Cassini orbiter mission are expanding our knowledge of the highest energy components of the Saturn magnetosphere in the inner radiation belt region after the initial discoveries of these belts by the Pioneer 11 and Voyager 2 missions. Saturn has a neutron exosphere that extends throughout the magnetosphere from the cosmic ray albedo neutron source at the planetary main rings and atmosphere. The neutrons emitted from these sources at energies respectively above 4 and 8 eV escape the Saturn system, while those at lower energies are gravitationally bound. The neutrons undergo beta decay in average times of about 1000 seconds to provide distributed sources of protons and electrons throughout Saturn's magnetosphere with highest injection rates close to the Saturn and ring sources. The competing radiation belt source for energetic electrons is rapid inward diffusion and acceleration of electrons from the middle magnetosphere and beyond. Minimal losses during diffusive transport across the moon orbits, e.g. of Mimas and Enceladus, and local time asymmetries in electron intensity, suggest that drift resonance effects preferentially boost the diffusion rates of electrons from both sources. Energy dependences of longitudinal gradient-curvature drift speeds relative to the icy moons are likely responsible for hemispheric differences (e.g., Mimas, Tethys) in composition and thermal properties as at least partly produced by radiolytic processes. A continuing mystery is the similar radial profiles of lower energy (belt region. Either the source of these lower energy protons is also neutron decay, but perhaps alternatively from atmospheric albedo, or else all protons from diverse distributed sources are similarly affected by losses at the moon' orbits, e.g. because the proton diffusion rates are extremely low. Enceladus cryovolcanism, and radiolytic processing elsewhere on the icy moon and ring surfaces, are additional

  6. Changes in the width of the tropical belt due to simple radiative forcing changes in the GeoMIP simulations

    Science.gov (United States)

    Davis, Nicholas A.; Seidel, Dian J.; Birner, Thomas; Davis, Sean M.; Tilmes, Simone

    2016-08-01

    Model simulations of future climates predict a poleward expansion of subtropical arid climates at the edges of Earth's tropical belt, which would have significant environmental and societal impacts. This expansion may be related to the poleward shift of the Hadley cell edges, where subsidence stabilizes the atmosphere and suppresses precipitation. Understanding the primary drivers of tropical expansion is hampered by the myriad forcing agents in most model projections of future climate. While many previous studies have examined the response of idealized models to simplified climate forcings and the response of comprehensive climate models to more complex climate forcings, few have examined how comprehensive climate models respond to simplified climate forcings. To shed light on robust processes associated with tropical expansion, here we examine how the tropical belt width, as measured by the Hadley cell edges, responds to simplified forcings in the Geoengineering Model Intercomparison Project (GeoMIP). The tropical belt expands in response to a quadrupling of atmospheric carbon dioxide concentrations and contracts in response to a reduction in the solar constant, with a range of a factor of 3 in the response among nine models. Models with more surface warming and an overall stronger temperature response to quadrupled carbon dioxide exhibit greater tropical expansion, a robust result in spite of inter-model differences in the mean Hadley cell width, parameterizations, and numerical schemes. Under a scenario where the solar constant is reduced to offset an instantaneous quadrupling of carbon dioxide, the Hadley cells remain at their preindustrial width, despite the residual stratospheric cooling associated with elevated carbon dioxide levels. Quadrupled carbon dioxide produces greater tropical belt expansion in the Southern Hemisphere than in the Northern Hemisphere. This expansion is strongest in austral summer and autumn. Ozone depletion has been argued to cause

  7. ATLAS-TPX: a two-layer pixel detector setup for neutron detection and radiation field characterization

    Science.gov (United States)

    Bergmann, B.; Caicedo, I.; Leroy, C.; Pospisil, S.; Vykydal, Z.

    2016-10-01

    A two-layer pixel detector setup (ATLAS-TPX), designed for thermal and fast neutron detection and radiation field characterization is presented. It consists of two segmented silicon detectors (256 × 256 pixels, pixel pitch 55 μm, thicknesses 300 μm and 500 μm) facing each other. To enhance the neutron detection efficiency a set of converter layers is inserted in between these detectors. The pixelation and the two-layer design allow a discrimination of neutrons against γs by pattern recognition and against charged particles by using the coincidence and anticoincidence information. The neutron conversion and detection efficiencies are measured in a thermal neutron field and fast neutron fields with energies up to 600 MeV. A Geant4 simulation model is presented, which is validated against the measured detector responses. The reliability of the coincidence and anticoincidence technique is demonstrated and possible applications of the detector setup are briefly outlined.

  8. NEUTRON CAPTURE GAMMA RAY FIELD WITH ENERGY TO 10 MeV FOR METROLOGICAL SUPPORT OF RADIATION PROTECTION DEVICES

    Directory of Open Access Journals (Sweden)

    D. I. Komar

    2016-01-01

    Full Text Available Medical, and technological linear particle accelerators, and nuclear reactors are vastly widespread worldwide today. These facility generate fields of secondary gamma radiation with energy to 10 MeV. Therefore, we have a need to calibrate spectrometric and dosimetric ionization measurement instruments for the energies to 10 MeV. The aim of this work is to determine possibility to use thermal neutron collimator of АТ140 Neutron Calibration Facility with 238Pu-Be fast neutron source (IBN-8-6 for this. Below 3 MeV we use a set of point gamma standard spectrometry sources OSGI. We can acquire gamma rays with energies above 3 MeV using radioactive thermal neutron capture on target, i.e. (n, γ-nuclear reaction. We can use neutron capture gamma-ray from titanium target (to 7 MeV or nickel target (to 10 MeV situated in thermal neutron field for calibration. We can use thermal neutron collimator of АТ140 Neutron Calibration Facility with 238Pu-Be fast neutron source (IBN-8-6 for slowing down neutrons from radionuclide fast neutron sources to thermal energies in polyethylene. Thermal neutron collimator forms a beam from radionuclide source with a significant amount of neutrons with thermal energies. We placed Ti and Ni targets in collimator’s canal. We got experimental spectral data on detection unit BDKG-19M NaI(Tl 63 × 160 mm with nonlinear channel-energy conversion characteristic in range to 10 MeV. For additional filtration we proposed to use polyethylene neutron reflector and lead discs. We experimentally determined that placement of lead discs in collimator in front of the target allows to filter all spectrum while insignificantly weakening target’s emission. Using theoretical and experimental data we proved the ability to calibrate gamma-ray spectrometers in the range to 10 MeV. 

  9. Concrete shielding of neutron radiations of plasma focus and dose examination by FLUKA

    Science.gov (United States)

    Nemati, M. J.; Amrollahi, R.; Habibi, M.

    2013-07-01

    Plasma Focus (PF) is among those devices which are used in plasma investigations, but this device produces some dangerous radiations after each shot, which generate a hazardous area for the operators of this device; therefore, it is better for the operators to stay away as much as possible from the area, where plasma focus has been placed. In this paper FLUKA Monte Carlo simulation has been used to calculate radiations produced by a 4 kJ Amirkabir plasma focus device through different concrete shielding concepts with various thicknesses (square, labyrinth and cave concepts). The neutron yield of Amirkabir plasma focus at varying deuterium pressure (3-9 torr) and two charging voltages (11.5 and 13.5 kV) is (2.25 ± 0.2) × 108 neutrons/shot and (2.88 ± 0.29) × 108 neutrons/shot of 2.45 MeV, respectively. The most influential shield for the plasma focus device among these geometries is the labyrinth concept on four sides and the top with 20 cm concrete.

  10. Investigation of 186Re via radiative thermal-neutron capture on 185Re

    Science.gov (United States)

    Matters, D. A.; Lerch, A. G.; Hurst, A. M.; Szentmiklósi, L.; Carroll, J. J.; Detwiler, B.; Révay, Zs.; McClory, J. W.; McHale, S. R.; Firestone, R. B.; Sleaford, B. W.; Krtička, M.; Belgya, T.

    2016-05-01

    Partial γ -ray production cross sections and the total radiative thermal-neutron capture cross section for the 185Re(n ,γ ) 186Re reaction were measured using the Prompt Gamma Activation Analysis facility at the Budapest Research Reactor with an enriched 185Re target. The 186Re cross sections were standardized using well-known 35Cl(n ,γ )36Cl cross sections from irradiation of a stoichiometric natReCl3 target. The resulting cross sections for transitions feeding the 186Re ground state from low-lying levels below a cutoff energy of Ec=746 keV were combined with a modeled probability of ground-state feeding from levels above Ec to arrive at a total cross section of σ0=111 (6 ) b for radiative thermal-neutron capture on 185Re. A comparison of modeled discrete-level populations with measured transition intensities led to proposed revisions for seven tentative spin-parity assignments in the adopted level scheme for 186Re. Additionally, 102 primary γ rays were measured, including 50 previously unknown. A neutron-separation energy of Sn=6179.59 (5 ) keV was determined from a global least-squares fit of the measured γ -ray energies to the known 186Re decay scheme. The total capture cross section and separation energy results are comparable to earlier measurements of these values.

  11. Conotruncal anomalies induced in chick embryos by 2 MeV neutron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Tsukasa (Tokyo Women' s Medical Coll. (Japan))

    1984-06-01

    Radiation of 2 MeV neutrons was used to induce conotruncal anomalies experimentally in chick. White leghorn eggs were exposed to a single dose of neutrons ranging from 50 to 250 rads at various stages of the development. Cardiovascular anomalies were found in 209(40%) of 526 treated embryos;conotruncal anomalies (81/209 or 39%), simple VSD (56/209 or 27%), isolated aortic arch anomalies (69/209 or 33%) and others (3/209 or 1%). The conotruncal anomalies were induced at considerably high incidences by exposures during the 3rd day of incubation and the highest incidence was 74% in the cases malformed by 220 rads. The types of conotruncal anomalies observed were as follows: VSD with pulmonary overriding (52 cases), VSD with aortic overriding (11 cases), DORV (10 cases), truncus arteriosus (6 cases) and complete TGA (2 cases). Sixty (74%) of these cases had aortic hypoplasia, constituting coarctation or interruption complex similar to that seen in man. It is generally thought that the experimental production of complete TGA in chick appears to be impossible when utilizing ordinary teratogenic means. However, neutron radiation could induce this peculiar anomaly in chick.

  12. Information Width

    CERN Document Server

    Ratsaby, Joel

    2008-01-01

    Kolmogorov argued that the concept of information exists also in problems with no underlying stochastic model (as Shannon's information representation) for instance, the information contained in an algorithm or in the genome. He introduced a combinatorial notion of entropy and information $I(x:\\sy)$ conveyed by a binary string $x$ about the unknown value of a variable $\\sy$. The current paper poses the following questions: what is the relationship between the information conveyed by $x$ about $\\sy$ to the description complexity of $x$ ? is there a notion of cost of information ? are there limits on how efficient $x$ conveys information ? To answer these questions Kolmogorov's definition is extended and a new concept termed {\\em information width} which is similar to $n$-widths in approximation theory is introduced. Information of any input source, e.g., sample-based, general side-information or a hybrid of both can be evaluated by a single common formula. An application to the space of binary functions is con...

  13. Determination of radiation levels by neutrons in an accelerator for radiotherapy; Determinacion de niveles de radiacion por neutrones en un acelerador para radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Paredes G, L.; Salazar B, M.A. [Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801 Mexico D.F. (Mexico); Genis S, R. [Fundacion Clinica Medica Sur, Puente de Piedra 150, Col. Torriello Guerra, Tlalpan 14050, Mexico D.F. (Mexico)

    1998-12-31

    It was determined the radiation levels by neutrons due to photonuclear reactions ({gamma}, n) which occur in the target, levelling filter, collimators and the small pillow blinding of a medical accelerator Varian Clinac 2100C of 18 MeV, using thermoluminescent dosemeters UD-802AS and US-809AS. The experimental values were presented for the patient level, inside and outside of the radiation field, as well as for the small pillow. (Author)

  14. A case of radiation-induced osteosarcoma treated effectively by boron neutron capture therapy.

    Science.gov (United States)

    Futamura, Gen; Kawabata, Shinji; Siba, Hiroyuki; Kuroiwa, Toshihiko; Suzuki, Minoru; Kondo, Natsuko; Ono, Koji; Sakurai, Yoshinori; Tanaka, Minoru; Todo, Tomoki; Miyatake, Shin-Ichi

    2014-11-04

    We treated a 54-year-old Japanese female with a recurrent radiation-induced osteosarcoma arising from left occipital skull, by reactor-based boron neutron capture therapy (BNCT). Her tumor grew rapidly with subcutaneous and epidural extension. She eventually could not walk because of cerebellar ataxia. The tumor was inoperable and radioresistant. BNCT showed a marked initial therapeutic effect: the subcutaneous/epidural tumor reduced without radiation damage of the scalp except hair loss and the patient could walk again only 3 weeks after BNCT. BNCT seems to be a safe and very effective modality in the management of radiation-induced osteosarcomas that are not eligible for operation and other treatment modalities.

  15. Radiative properties of magnetic neutron stars with metallic surfaces and thin atmospheres

    CERN Document Server

    Potekhin, A Y; van Adelsberg, M; Werner, K

    2012-01-01

    The goal of this work is to develop a simple analytic description of the emission properties (spectrum and polarization) of the condensed, strongly magnetized surface of neutron stars. We have improved the method of van Adelsberg et al. (2005) (arXiv:astro-ph/0406001) for calculating the spectral properties of condensed magnetized surfaces. Using the improved method, we calculate the reflectivity of an iron surface at magnetic field strengths B \\sim (10^{12} - 10^{14}) G, with various inclinations of the magnetic field lines and radiation beam with respect to the surface and each other. We construct analytic expressions for the emissivity of this surface as functions of the photon energy, magnetic field strength, and the three angles that determine the geometry of the local problem. Using these expressions, we calculate X-ray spectra for neutron stars with condensed iron surfaces covered by thin partially ionized hydrogen atmospheres. We develop simple analytic descriptions of the intensity and polarization o...

  16. Neutron and Synchrotron Radiation Studies for Designer Materials, Sustainable Energy and Healthy Lives

    Science.gov (United States)

    Gibson, J. Murray

    2009-05-01

    Probably the most prolific use of large accelerators today is in the creation of bright beams of x-ray photons or neutrons. The number of scientific users of such sources in the US alone is approaching 10,000. I will describe the some of the major applications of synchrotron and neutron radiation and their impact on society. If you have AIDS, need a better IPOD or a more efficient car, or want to clean up a superfund site, you are benefitting from these accelerators. The design of new materials is becoming more and more dependent on structural information from these sources. I will identify the trends in applications which are demanding new sources with greater capabilities.

  17. Optimising the neutron environment of Radiation Portal Monitors: a computational optimisation study

    CERN Document Server

    Gilbert, Mark R; Packer, Lee W

    2015-01-01

    Efficient and reliable detection of radiological or nuclear threats is a crucial part of national and international efforts to prevent terrorist activities. Radiation Portal Monitors (RPMs), which are deployed worldwide, are intended to interdict smuggled fissile material by detecting emissions of neutrons and gamma rays. However, considering the range and variety of threat sources, vehicular and shielding scenarios, and that only a small signature is present, it is important that the design of the RPMs allows these signatures to be accurately differentiated from the environmental background. Using Monte-Carlo neutron-transport simulations of a model helium-3 detector system we have conducted a parameter study to identify the optimum combination of detector shielding and collimation that maximises the sensitivity of RPMs. These structures, which could be simply and cost-effectively added to existing RPMs, can improve the detector response by more than a factor of two relative to an unmodified, bare design. Fu...

  18. Description of the proton and neutron radiative capture reactions in the Gamow shell model

    CERN Document Server

    Fossez, K; Płoszajczak, M; Jaganathen, Y

    2015-01-01

    We formulate the Gamow shell model (GSM) in coupled-channel (CC) representation for the description of proton/neutron radiative capture reactions and present the first application of this new formalism for the calculation of cross-sections in mirror reactions 7Be(p,gamma)8B and 7Li(n,gamma)8Li. The GSM-CC formalism is applied to a translationally-invariant Hamiltonian with an effective finite-range two-body interaction. Reactions channels are built by GSM wave functions for the ground state 3/2- and the first excited state 1/2- of 7Be/7Li and the proton/neutron wave function expanded in different partial waves.

  19. Field calibration of PADC track etch detectors for local neutron dosimetry in man using different radiation qualities

    Energy Technology Data Exchange (ETDEWEB)

    Haelg, Roger A., E-mail: rhaelg@phys.ethz.ch [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Besserer, Juergen [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Boschung, Markus; Mayer, Sabine [Division for Radiation Safety and Security, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Clasie, Benjamin [Department of Radiation Oncology, Massachusetts General Hospital, 30 Fruit Street, Boston, MA 02114 (United States); Kry, Stephen F. [Department of Radiation Physics, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030 (United States); Schneider, Uwe [Institute for Radiotherapy, Radiotherapie Hirslanden AG, Hirslanden Medical Center, Rain 34, CH-5000 Aarau (Switzerland); Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 204, CH-8057 Zurich (Switzerland)

    2012-12-01

    In order to quantify the dose from neutrons to a patient for contemporary radiation treatment techniques, measurements inside phantoms, representing the patient, are necessary. Published reports on neutron dose measurements cover measurements performed free in air or on the surface of phantoms and the doses are expressed in terms of personal dose equivalent or ambient dose equivalent. This study focuses on measurements of local neutron doses inside a radiotherapy phantom and presents a field calibration procedure for PADC track etch detectors. An initial absolute calibration factor in terms of H{sub p}(10) for personal dosimetry is converted into neutron dose equivalent and additional calibration factors are derived to account for the spectral changes in the neutron fluence for different radiation therapy beam qualities and depths in the phantom. The neutron spectra used for the calculation of the calibration factors are determined in different depths by Monte Carlo simulations for the investigated radiation qualities. These spectra are used together with the energy dependent response function of the PADC detectors to account for the spectral changes in the neutron fluence. The resulting total calibration factors are 0.76 for a photon beam (in- and out-of-field), 1.00 (in-field) and 0.84 (out-of-field) for an active proton beam and 1.05 (in-field) and 0.91 (out-of-field) for a passive proton beam, respectively. The uncertainty for neutron dose measurements using this field calibration method is less than 40%. The extended calibration procedure presented in this work showed that it is possible to use PADC track etch detectors for measurements of local neutron dose equivalent inside anthropomorphic phantoms by accounting for spectral changes in the neutron fluence.

  20. Managing NIF safety equipment in a high neutron and gamma radiation environment.

    Science.gov (United States)

    Datte, Philip; Eckart, Mark; Jackson, Mark; Khater, Hesham; Manuel, Stacie; Newton, Mark

    2013-06-01

    The National Ignition Facility (NIF) is a 192 laser beam facility that supports the Inertial Confinement Fusion program. During the ignition experimental campaign, the NIF is expected to perform shots with varying fusion yield producing 14 MeV neutrons up to 20 MJ or 7.1 × 10(18) neutrons per shot and a maximum annual yield of 1,200 MJ. Several infrastructure support systems will be exposed to varying high yield shots over the facility's 30-y life span. In response to this potential exposure, analysis and testing of several facility safety systems have been conducted. A detailed MCNP (Monte Carlo N-Particle Transport Code) model has been developed for the NIF facility, and it includes most of the major structures inside the Target Bay. The model has been used in the simulation of expected neutron and gamma fluences throughout the Target Bay. Radiation susceptible components were identified and tested to fluences greater than 10(13) (n cm(-2)) for 14 MeV neutrons and γ-ray equivalent. The testing includes component irradiation using a 60Co gamma source and accelerator-based irradiation using 4- and 14- MeV neutron sources. The subsystem implementation in the facility is based on the fluence estimates after shielding and survivability guidelines derived from the dose maps and component tests results. This paper reports on the evaluation and implementation of mitigations for several infrastructure safety support systems, including video, oxygen monitoring, pressure monitors, water sensing systems, and access control interfaces found at the NIF.

  1. Metrology and quality of radiation therapy dosimetry of electron, photon and epithermal neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Kosunen, A

    1999-08-01

    In radiation therapy using electron and photon beams the dosimetry chain consists of several sequential phases starting by the realisation of the dose quantity in the Primary Standard Dosimetry Laboratory and ending to the calculation of the dose to a patient. A similar procedure can be described for the dosimetry of epithermal neutron beams in boron neutron capture therapy (BNCT). To achieve the required accuracy of the dose delivered to a patient the quality of all steps in the dosimetry procedure has to be considered. This work is focused on two items in the dosimetry chains: the determination of the dose in the reference conditions and the evaluation of the accuracy of dose calculation methods. The issues investigated and discussed in detail are: a)the calibration methods of plane parallel ionisation chambers used in electron beam dosimetry, (b) the specification of the critical dosimetric parameter i.e. the ratio of stopping powers for water to air, (S I ?){sup water} {sub air}, in photon beams, (c) the feasibility of the twin ionization chamber technique for dosimetry in epithermal neutron beams applied to BNCT and (d) the determination accuracy of the calculated dose distributions in phantoms in electron, photon, and epithermal neutron beams. The results demonstrate that up to a 3% improvement in the consistency of dose determinations in electron beams is achieved by the calibration of plane parallel ionisation chambers in high energy electron beams instead of calibrations in {sup 60}Co gamma beams. In photon beam dosimetry (S I ?){sup water} {sub air} can be determined with an accuracy of 0.2% using the percentage dose at the 10 cm depth, %dd(10), as a beam specifier. The use of %odd(10) requires the elimination of the electron contamination in the photon beam. By a twin ionisation chamber technique the gamma dose can be determined with uncertainty of 6% (1 standard deviation) and the total neutron dose with an uncertainty of 15 to 20% (1 standard deviation

  2. WIDTHS AND AVERAGE WIDTHS OF SOBOLEV CLASSES

    Institute of Scientific and Technical Information of China (English)

    刘永平; 许贵桥

    2003-01-01

    This paper concerns the problem of the Kolmogorov n-width, the linear n-width, the Gel'fand n-width and the Bernstein n-width of Sobolev classes of the periodicmultivariate functions in the space Lp(Td) and the average Bernstein σ-width, averageKolmogorov σ-widths, the average linear σ-widths of Sobolev classes of the multivariatequantities.

  3. Correlation of clinical outcome to the estimated radiation dose from Boron Neutron Capture Therapy (BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Chadha, M. [Beth Israel Medical Center, NY (United States). Dept. of Radiation Oncology; Coderre, J.A.; Chanana, A.D. [Brookhaven National Lab., Upton, NY (United States)] [and others

    1996-12-31

    A phase I/II trial delivering a single fraction of BNCT using p-Boronophenylalanine-Fructose and epithermal neutrons at the the Brookhaven Medical Research Reactor was initiated in September 1994. The primary endpiont of the study was to evaluate the feasibility and safety of a given BNCT dose. The clinical outcome of the disease was a secondary endpoint of the study. The objective of this paper is to evaluate the correlation of the clinical outcome of patients to the estimated radiation dose from BNCT.

  4. Correlation of clinical outcome to the estimated radiation dose from Boron Neutron Capture Therapy (BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Chadha, M. [Beth Israel Medical Center, NY (United States). Dept. of Radiation Oncology; Coderre, J.A.; Chanana, A.D. [Brookhaven National Lab., Upton, NY (United States)] [and others

    1996-12-31

    A phase I/II trial delivering a single fraction of BNCT using p-Boronophenylalanine-Fructose and epithermal neutrons at the the Brookhaven Medical Research Reactor was initiated in September 1994. The primary endpiont of the study was to evaluate the feasibility and safety of a given BNCT dose. The clinical outcome of the disease was a secondary endpoint of the study. The objective of this paper is to evaluate the correlation of the clinical outcome of patients to the estimated radiation dose from BNCT.

  5. Constraints on Thermal X-Ray Radiation from SAX J1808.4-3658 and Implications for Neutron Star Neutrino Emission

    NARCIS (Netherlands)

    C.O. Heinke; P.G. Jonker; R. Wijnands; R.E. Taam

    2007-01-01

    Thermal X-ray radiation from neutron star soft X-ray transients in quiescence provides the strongest constraints on the cooling rates of neutron stars and thus on the interior composition and properties of matter in the cores of neutron stars. We analyze new (2006) and archival (2001) XMM-Newton obs

  6. Modelling of neutron and photon transport in iron and concrete radiation shieldings by the Monte Carlo method - Version 2

    CERN Document Server

    Žukauskaite, A; Plukiene, R; Plukis, A

    2007-01-01

    Particle accelerators and other high energy facilities produce penetrating ionizing radiation (neutrons and γ-rays) that must be shielded. The objective of this work was to model photon and neutron transport in various materials, usually used as shielding, such as concrete, iron or graphite. Monte Carlo method allows obtaining answers by simulating individual particles and recording some aspects of their average behavior. In this work several nuclear experiments were modeled: AVF 65 – γ-ray beams (1-10 MeV), HIMAC and ISIS-800 – high energy neutrons (20-800 MeV) transport in iron and concrete. The results were then compared with experimental data.

  7. Measurements of the high energy neutron component of cosmic radiation fields in aircraft using etched track dosemeters

    CERN Document Server

    Bartlett, D T; Tanner, R J; Steele, J D

    2001-01-01

    Measurements of the complex cosmic radiation field in aircraft at altitude are made with a passive survey meter comprising routine-use thermoluminescent detectors and etched track detectors. The energy dependence of response of the etched track detectors used to determine the neutron component has been characterized, partly, up to a neutron energy of 180 MeV. The neutron detectors are routinely calibrated in the CERN EC Ref.Field. The 15% determination level for total dose equivalent is 100 mu Sv. The evidence is that the passive survey meter provides a reliable determination of route dose. (41 refs).

  8. Optimising the neutron environment of Radiation Portal Monitors: A computational study

    Science.gov (United States)

    Gilbert, Mark R.; Ghani, Zamir; McMillan, John E.; Packer, Lee W.

    2015-09-01

    Efficient and reliable detection of radiological or nuclear threats is a crucial part of national and international efforts to prevent terrorist activities. Radiation Portal Monitors (RPMs), which are deployed worldwide, are intended to interdict smuggled fissile material by detecting emissions of neutrons and gamma rays. However, considering the range and variety of threat sources, vehicular and shielding scenarios, and that only a small signature is present, it is important that the design of the RPMs allows these signatures to be accurately differentiated from the environmental background. Using Monte-Carlo neutron-transport simulations of a model 3He detector system we have conducted a parameter study to identify the optimum combination of detector shielding, moderation, and collimation that maximises the sensitivity of neutron-sensitive RPMs. These structures, which could be simply and cost-effectively added to existing RPMs, can improve the detector response by more than a factor of two relative to an unmodified, bare design. Furthermore, optimisation of the air gap surrounding the helium tubes also improves detector efficiency.

  9. Optimising the neutron environment of Radiation Portal Monitors: A computational study

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Mark R., E-mail: mark.gilbert@ccfe.ac.uk [United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Ghani, Zamir [United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); McMillan, John E. [Department of Physics and Astronomy, University of Sheffield, Hicks building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Packer, Lee W. [United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

    2015-09-21

    Efficient and reliable detection of radiological or nuclear threats is a crucial part of national and international efforts to prevent terrorist activities. Radiation Portal Monitors (RPMs), which are deployed worldwide, are intended to interdict smuggled fissile material by detecting emissions of neutrons and gamma rays. However, considering the range and variety of threat sources, vehicular and shielding scenarios, and that only a small signature is present, it is important that the design of the RPMs allows these signatures to be accurately differentiated from the environmental background. Using Monte-Carlo neutron-transport simulations of a model {sup 3}He detector system we have conducted a parameter study to identify the optimum combination of detector shielding, moderation, and collimation that maximises the sensitivity of neutron-sensitive RPMs. These structures, which could be simply and cost-effectively added to existing RPMs, can improve the detector response by more than a factor of two relative to an unmodified, bare design. Furthermore, optimisation of the air gap surrounding the helium tubes also improves detector efficiency.

  10. RBE of quasi-monoenergetic 60 MeV neutron radiation for induction of dicentric chromosomes in human lymphocytes.

    Science.gov (United States)

    Nolte, R; Mühlbradt, K-H; Meulders, J P; Stephan, G; Haney, M; Schmid, E

    2005-12-01

    The production of dicentric chromosomes in human lymphocytes by high-energy neutron radiation was studied using a quasi-monoenergetic 60 MeV neutron beam. The average yield coefficient [see text] of the linear dose-response relationship for dicentric chromosomes was measured to be (0.146+/-0.016) Gy-1. This confirms our earlier observations that above 400 keV, the yield of dicentric chromosomes decreases with increasing neutron energy. Using the linear-quadratic dose-response relationship for dicentric chromosomes established in blood of the same donor for 60Co gamma-rays as a reference radiation, an average maximum low-dose RBE (RBEM) of 14+/-4 for 60 MeV quasi-monoenergetic neutrons with a dose-weighted average energy [see text] of 41.0 MeV is obtained. A correction procedure was applied, to account for the low-energy continuum of the quasi-monoenergetic spectral neutron distribution, and the yield coefficient alpha for 60 MeV neutrons was determined from the measured average yield coefficient [see text]. For alpha, a value of (0.115+/-0.026) Gy-1 was obtained corresponding to an RBEM of 11+/-4. The present experiments extend earlier investigations with monoenergetic neutrons to higher energies.

  11. Radiative corrections to the magnetic moments of the proton and the neutron

    CERN Document Server

    Kaiser, N

    2016-01-01

    We estimate the radiative corrections of order $\\alpha/\\pi$ to the magnetic moments of the proton and the neutron. The photon-loop diagram of the vertex-correction type is evaluated with phenomenological nucleon vector form factors. Infrared-finiteness and gauge-invariance require the inclusion of the wave-function renormalization factor from the self-energy diagram. Using recent empirical form factor parametrizations the corrections amount to $\\delta\\kappa_p= -3.42 \\cdot 10^{-3}$ and $\\delta\\kappa_n= 1.34 \\cdot 10^{-3}$. We study also the effects from photon-loops with internal $\\Delta(1232)$-isobars. For two customary versions of the $\\Delta N\\gamma $-vertex and spin-3/2 propagator, these radiative corrections have values of $\\delta\\kappa_p^{(\\Delta)}= (-0.9,\\, 0.0)\\!\\cdot\\! 10^{-3}$ and $\\delta\\kappa_n^{(\\Delta)} = (1.2,\\,-0.8)\\!\\cdot\\! 10^{-3}$, respectively.

  12. Neutrons and synchrotron radiation in engineering materials science from fundamentals to applications

    CERN Document Server

    Schreyer, Andreas; Clemens, Helmut; Mayer, Svea

    2017-01-01

    Retaining its proven concept, the second edition of this ready reference specifically addresses the need of materials engineers for reliable, detailed information on modern material characterization methods. As such, it provides a systematic overview of the increasingly important field of characterization of engineering materials with the help of neutrons and synchrotron radiation. The first part introduces readers to the fundamentals of structure-property relationships in materials and the radiation sources suitable for materials characterization. The second part then focuses on such characterization techniques as diffraction and scattering methods, as well as direct imaging and tomography. The third part presents new and emerging methods of materials characterization in the field of 3D characterization techniques like three-dimensional X-ray diffraction microscopy. The fourth and final part is a collection of examples that demonstrate the application of the methods introduced in the first parts to probl...

  13. Novel technologies and theoretical models in radiation therapy of cancer patients using 6.3 MeV fast neutrons produced by U-120 cyclotron

    Science.gov (United States)

    Musabaeva, L. I.; Startseva, Zh. A.; Gribova, O. V.; Velikaya, V. V.; Lisin, V. A.

    2016-08-01

    The analysis of clinical use of neutron therapy with 6 MeV fast neutrons compared to conventional radiation therapy was carried out. The experience of using neutron and mixed neutron and photon therapy in patients with different radio-resistant malignant tumors shows the necessity of further studies and development of the novel approaches to densely-ionizing radiation. The results of dosimetry and radiobiological studies have been the basis for planning clinical programs for neutron therapy. Clinical trials over the past 30 years have shown that neutron therapy successfully destroys radio-resistant cancers, including salivary gland tumors, adenoidcystic carcinoma, inoperable sarcomas, locally advanced head and neck tumors, and locally advanced prostate cancer. Radiation therapy with 6.3 MeV fast neutrons used alone and in combination with photon therapy resulted in improved long-term treatment outcomes in patients with radio-resistant malignant tumors.

  14. Novel technologies and theoretical models in radiation therapy of cancer patients using 6.3 MeV fast neutrons produced by U-120 cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Musabaeva, L. I., E-mail: musabaevaLI@oncology.tomsk.ru; Lisin, V. A., E-mail: Lisin@oncology.tomsk.ru [Tomsk Cancer Research Institute, Kooperativny Street 5, Tomsk, 634050 (Russian Federation); Startseva, Zh. A., E-mail: zhanna.alex@rambler.ru; Gribova, O. V., E-mail: gribova79@mail.ru; Velikaya, V. V., E-mail: viktoria.v.v@inbox.ru [Tomsk Cancer Research Institute, Kooperativny Street 5, Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, Lenin Avenue 30, Tomsk, 634050 (Russian Federation)

    2016-08-02

    The analysis of clinical use of neutron therapy with 6 MeV fast neutrons compared to conventional radiation therapy was carried out. The experience of using neutron and mixed neutron and photon therapy in patients with different radio-resistant malignant tumors shows the necessity of further studies and development of the novel approaches to densely-ionizing radiation. The results of dosimetry and radiobiological studies have been the basis for planning clinical programs for neutron therapy. Clinical trials over the past 30 years have shown that neutron therapy successfully destroys radio-resistant cancers, including salivary gland tumors, adenoidcystic carcinoma, inoperable sarcomas, locally advanced head and neck tumors, and locally advanced prostate cancer. Radiation therapy with 6.3 MeV fast neutrons used alone and in combination with photon therapy resulted in improved long-term treatment outcomes in patients with radio-resistant malignant tumors.

  15. Radiation damage to neutron and proton irradiated GaAs particle detectors

    CERN Document Server

    Rogalla, M; Evans, N; Joost, S; Kienzle-Focacci, M N; Geppert, R; Göppert, R; Irsigler, R; Ludwig, J; Runge, K; Schmid, T; Eich, Th.; Schmid, Th.

    1997-01-01

    The radiation damage in 200 um thick Schottky diodes made on semi-insulating (SI) undoped GaAs Liquid Encapsulated Czochralski (LEC) bulk material with resistivities between 0.4 and 8.9*10E7 Ohm*cm were studied using alpha-spectroscopy, signal response to minimum ionising particles (MIP), I-V and CV-measurements. The results have been analysed to investigate the influence of the substrate resistivity on the detector performance after neutron and proton irradiation. The leakage current density, signal response to alpha-particles and MIPs show a strong dependence on the resistivity before and after irradiation. An observed decrease of the electron mean free drift length before and after irradiation with increasing substrate resistivity can be explained by a model involving the different ionisation ratios of defects, which are introduced by the irradiation. Comparison of the radiation damage due to neutrons and protons gives a hardness factor of 7+-0.9 for 24 GeV/c protons. The best detectors show a response to ...

  16. FMC-based Neutron and Gamma Radiation Monitoring Module for xTCA Applications

    CERN Document Server

    Kozak, T; Napieralski, A

    2012-01-01

    The machines used in High Energy Physics (HEP) experiments, such as accelerators or tokamaks, are sources of gamma and neutron radiation fields. The radiation has a negative influence on electronics and can lead to the incorrect functioning of complex control and diagnostic system designed for HEP machines. Therefore, in most cases the electronic equipments is installed in radiation-safe areas, but in some cases this rule is omitted to decrease costs of the project. The European X-ray Free Electron Laser (E-XFEL), being under construction at DESY research center, is a good example. The E-XFEL uses single tunnel and part of the electronic system will be installed next to main beam pipe and exposed to radiation. The modern Advanced/Micro Telecommunications Computing Architecture (ATCA/μTCA) standards are foreseen as a base for control and diagnostic system for this new project. These flexible standards provide high reliability, availability and usability for the system which can be decreased by negative influe...

  17. A benchmark analysis of radiation flux distribution for Boron Neutron Capture Therapy of canine brain tumors

    Energy Technology Data Exchange (ETDEWEB)

    Moran, J.M.

    1992-02-01

    Calculations of radiation flux and dose distributions for Boron Neutron Capture Therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly-heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This work describes a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador Retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador Retriever head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for the model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous tissue model. Comparison of the results showed that the peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10-20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.

  18. Modeling of neutron and photon transport in iron and concrete radiation shields by using Monte Carlo method

    CERN Document Server

    Žukauskaitėa, A; Plukienė, R; Ridikas, D

    2007-01-01

    Particle accelerators and other high energy facilities produce penetrating ionizing radiation (neutrons and γ-rays) that must be shielded. The objective of this work was to model photon and neutron transport in various materials, usually used as shielding, such as concrete, iron or graphite. Monte Carlo method allows obtaining answers by simulating individual particles and recording some aspects of their average behavior. In this work several nuclear experiments were modeled: AVF 65 (AVF cyclotron of Research Center of Nuclear Physics, Osaka University, Japan) – γ-ray beams (1-10 MeV), HIMAC (heavy-ion synchrotron of the National Institute of Radiological Sciences in Chiba, Japan) and ISIS-800 (ISIS intensive spallation neutron source facility of the Rutherford Appleton laboratory, UK) – high energy neutron (20-800 MeV) transport in iron and concrete. The calculation results were then compared with experimental data.compared with experimental data.

  19. A neutron activation system for Ho, HoZr and Sm brachytherapy seeds for breast radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Wagner L., E-mail: wagner.leite@ifmg.edu.br [Instituto Federal de Minas Gerais (IFMG), Congonhas, MG (Brazil). Departamento de Fisica; Campos, Tarcisio P.R., E-mail: tprcampos@pq.cnpq.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2015-07-01

    This paper addresses a device designed for transmuting nuclides by means of neutron capture reactions. The device is composed by a neutron generator based on d-d reactions, a neutron moderator and a reflection system, enclosed by a radiation shield. The project was modeled on the CST electromagnetic code. Afterwards, a nuclear investigation was carried out by MCNP5 code, where the final activities of a large set of 0.5 x 1.8 mm cylindrical, biodegradable and biocompatible, Ho-165 (Ho and HoZr) and Sm-152 breast brachytherapy seeds were evaluated, considering the neutron capture reactions. The accelerator-head equipotential profiles and the optical beam of deuterons with its energy map were presented. The neutronic evaluation allowed estimating a neutron yield of 10{sup 13} n s{sup -1}. From the seed's group, an individual Ho-166 seed reached activity of 100 MBq in 58 h operation time. Moreover, Sm-153 seed reached 120 MBq during a period of 64 h of operation. The system shows to be able to provide the neutron activation of brachytherapy seeds with suitable individual specific activity able for controlling breast tumors. (author)

  20. Hydrothermal growth and characterization of UO2 single crystals for neutron radiation detection(Conference Presentation)

    Science.gov (United States)

    Mann, Matthew; Hunt, Eric; Young, Christopher; Kimani, Martin; Turner, David; Varga, Stephan; Petrosky, James

    2016-09-01

    There is significant interest in developing efficient, direct conversion, neutron sensitive solid-state radiation detector materials with the ability to discriminate between photon and neutron events. Recently, this has led several research groups to pursue uranium dioxide (UO2) single crystals as a detection material due to the large reaction energy ( 185 MeV) from a neutron induced fission event. The resulting electrical pulse, generated primarily by the energetic fission fragments, is expected to be on the order of 165 MeV, which is much greater than current detection schemes which rely on reaction energies between 2-6 MeV. The primary technical challenge to the successful fabrication of UO2 devices is the lack of high quality (semiconductor grade) single crystals of UO2. The high melting point of UO2 ( 2878°C) precludes the use of traditional melt growth techniques like Czochralski. While exotic melt growth techniques such as arc fusion, cold crucible, and solar furnace have successfully grown UO2, the crystal quality suffers from both thermal strain and oxygen non-stoichiometry, two particularly difficult challenges inherent to uranium oxide materials. Crystal growth of UO2 by the hydrothermal synthesis technique has never been investigated, although the method has been successfully applied to the synthesis of other refractory oxides. In this talk, we will present growth of UO2 single crystals from a variety of hydrothermal solutions at temperatures below 650C. X-ray diffraction confirmed the stoichiometric nature of the samples and X-ray photoelectron spectroscopy determined the photoelectric work function of two crystal orientations. Preliminary proof-of-concept irradiation studies of a simple UO2 resistive detector will also be presented.

  1. Radiation embrittlement of the neutron shield tank from the Shippingport reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O.K.; Shack, W.J. (Argonne National Lab., IL (United States)); Rosinski, S.T. (Sandia National Labs., Albuquerque, NM (United States))

    1991-10-01

    The irradiation embrittlement of neutron shield tank (NST) material (A212 Grade B steel) from the Shippingport reactor has been characterized. Irradiation increases the Charpy transition temperature (CTT) by 23--28{degrees}C (41--50{degrees}F) and decreases the upper-shelf energy. The shift in CTT is not as severe as that observed in high-flux isotope reactor (HFIR) surveillance specimens. However, the actual value of the CTT is higher than that for the HFIR data. The increase in yield stress is 51 MPa (7.4 ksi), which is comparable to HFIR data. The NST material is weaker in the transverse orientation than in the longitudinal orientation. Some effects of position across the thickness of the wall are also observed; the CTT shift is slightly greater for specimens from the inner region of the wall. Annealing studies indicate complete recovery from embrittlement after 1 h at 400{degrees}C (752{degrees}F). Although the weld metal is significantly tougher than the base metal, the shifts in CTT are comparable. The shifts in CTT for the Shippingport NST are consistent with the test and Army reactor data for irradiations at <232{degrees}C (<450{degrees}F) and show very good agreement with the results for HFIR A212-B steel irradiated in the Oak Ridge Research Reactor (ORR). The effects of irradiation temperature, fluence rate, and neutron flux spectrum are discussed. The results indicate that fluence rate has no effect on radiation embrittlement at rates as low as 2 {times} 10{sup 8} n/cm{sup 2}{center dot}s and at the low operating temperatures of the Shippingport NST, i.e., 55{degrees}C (130{degrees}F). This suggests that the accelerated embrittlement of HFIR surveillance samples is most likely due to the relatively higher proportion of thermal neutrons in the HFIR spectrum compared to that for the test reactors. 28 refs., 25 figs.

  2. Radiation induced changes in electrical conductivity of chemical vapor deposited silicon carbides under fast neutron and gamma-ray irradiations

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Bun, E-mail: btsuchiya@meijo-u.ac.jp [Department of General Education, Faculty of Science and Technology, Meijo University, 1-501, Shiogamaguchi, Tempaku-ku, Nagoya 468-8502 (Japan); Shikama, Tatsuo; Nagata, Shinji; Saito, Kesami [Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yamamoto, Syunya [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233, Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Ohnishi, Seiki [Tokai Research and Development Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Nozawa, Takashi [Aomori Research and Development Center, Japan Atomic Energy Agency, 2-166, Omotedate, Obuchi, Rokkasho, Aomori 039-3212 (Japan)

    2011-10-15

    The radiation-induced changes in the volume electrical conductivities of chemical vapor deposited silicon carbides (CVD-SiCs) were in-site investigated by performing irradiation using 1.17 and 1.33-MeV gamma-ray and 14-MeV fast neutron beams in air and vacuum. Under gamma-ray irradiation at ionization dose rates of 3.6 and 5.9 Gy/s and irradiation temperature of approximately 300 K, the initial rapid increase in electrical conductivity; this is indicative of radiation-induced conductivity (RIC), occurred due to electronic excitation, and a more gradual increase followed up to a dose of approximately 10-50 kGy corresponding to the results in base conductivity without radiation; this is indicative of radiation-induced electrical degradation (RIED). However, the radiation-induced phenomena were not observed at irradiation temperatures above 373 K. Under neutron irradiation at a further low dose rate below approximately 2.1 Gy/s, a fast neutron flux of 9.2 x 10{sup 14} n/m{sup 2} s, and 300 K, the RIED-like behavior according to radiation-induced modification of the electrical property occurred with essentially no displacement damage, but ionizing effects (radiolysis).

  3. Effect of Neutron Radiation on Moment-Curvature Response of Reinforced Concrete Beam

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Taehyun; Kim, Jun Yeon; Cho, Mansoon; Wu, Sangik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Kyoungsoo [Yonsei Univ., Seoul (Korea, Republic of)

    2014-05-15

    Reinforced concrete (RC) is a composite material in which concrete resists compression and steel bars as reinforcement are embedded in tensile regions to counteract the concrete's relative low tensile strength and ductility. RC is commonly used as a biological shield and as a load carrying support for a reactor vessel and, if any, changes in the mechanical properties can be particular significant for long-term irradiation. The highlights can be considered as the most critical due to its load bearing in the RC design. This study investigated the moment-curvature response of an RC beam with incremental neutron radiation. The RC structure close to the reactor vessel was considered as the most critical in estimating that the total fluence for 40 years becomes about 10{sup 14} to 10{sup 18} n/cm{sup 2}. The moment-curvature response of an RC beam was investigated with the maximum neutron fluence up to 10{sup 19} n/cm{sup 2} and it shows twice the increase in ultimate strength, which is mainly contributed from the increased yield stress of mild steel. The RC beam response became so brittle that it may fail without large deformation as a warning. The same observation can be equally applied to other RC designs such as the column, slab, and foundation.

  4. Mosaic diamond detectors for fast neutrons and large ionizing radiation fields

    Energy Technology Data Exchange (ETDEWEB)

    Girolami, Marco; Calvani, Paolo; Trucchi, Daniele M. [Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), Rome (Italy); Bellucci, Alessandro [Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), Rome (Italy); Dipartimento di Fisica, Universita degli Studi di Roma ' ' La Sapienza' ' , Rome (Italy); Cazzaniga, Carlo; Rebai, Marica; Rigamonti, Davide [Dipartimento di Fisica, Universita degli Studi di Milano-Bicocca, Milano (Italy); Istituto di Fisica dei Plasmi (IFP), Consiglio Nazionale delle Ricerche (CNR), Milano (Italy); Tardocchi, Marco [Istituto di Fisica dei Plasmi (IFP), Consiglio Nazionale delle Ricerche (CNR), Milano (Italy); Pillon, Mario [ENEA, Centro Ricerche di Frascati, Rome (Italy)

    2015-11-15

    First neutron and X-ray beam tests on a novel 12-pixel single-crystal diamond mosaic detector are presented and discussed. Preliminary characterization of single-pixel electronic properties, performed with α particles, results in charge carrier mobilities >2000 cm{sup 2} Vs{sup -1} and saturation velocities of the order of 10{sup 7} cm s{sup -1}. Signal stability over time, measured with a {sup 241}Am source (37 kBq activity), is longer than 5 h. Tests under an intense X-ray beam (1 Gy h{sup -1} dose-rate) show a very good response uniformity (down to about 1% of relative standard deviation from mean value), suggesting a high level of pixel reproducibility at intermediate bias voltages (ranging from 20 to 100 V). Response uniformity reduces at voltages >200 V, due presumably to radiation-assisted detrapping effects. Preliminary results of 12-pixel simultaneous acquisitions of X-ray beam profiles and pulse height spectra under a fast neutron beam (14 MeV) are also presented. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Photon strength functions in Gd isotopes studied from radiative capture of resonance neutrons

    Directory of Open Access Journals (Sweden)

    Kroll J.

    2014-04-01

    Full Text Available The experimental spectra of γ rays following radiative neutron capture on isolated resonances of stable 152,154–158Gd targets were measured by the DANCE calorimeter installed at the Los Alamos Neutron Scattering Center in New Mexico, USA. These spectra were analyzed within the extreme statistical model to get new information on the photon strength functions. Special emphasis was put on study of the scissors vibrational mode present in these isotopes. Our data show that the scissors-mode resonances are built not only on the ground states but also on the excited levels of all studied Gd isotopes. The scissors mode strength observed in 157,159Gd products is significantly higher than in neighboring even-even nuclei 156,158Gd. Such a difference indicates the existence of an odd-even effect in the scissors mode strength. Moreover, there exists no universal parameter-free model of the electric dipole photon strength function describing the experimental data in all of the Gd isotopes studied. The results for the scissors mode are compared with the (γ, γ′ data for the ground-state transitions and with the results from 3He-induced reactions.

  6. Precision measurement of the radiative $\\beta$ decay of the free neutron

    CERN Document Server

    Bales, M J; Bass, C D; Beise, E J; Breuer, H; Byrne, J; Chupp, T E; Coakley, K J; Cooper, R L; Dewey, M S; Gardner, S; Gentile, T R; He, D; Mumm, H P; Nico, J S; O'Neill, B; Thompson, A K; Wietfeldt, F E

    2016-01-01

    The Standard Model predicts that, in addition to a proton, an electron, and an antineutrino, a continuous spectrum of photons is emitted in the $\\beta$ decay of the free neutron. We report on the RDK II experiment which measured the photon spectrum using two different detector arrays. An annular array of bismuth germanium oxide scintillators detected photons from 14~keV to 782~keV. The spectral shape was consistent with theory, and we determined a branching ratio of 0.00335 $\\pm$ 0.00005 [stat] $\\pm$ 0.00015 [syst]. A second detector array of large area avalanche photodiodes directly detected photons from 0.4~keV to 14~keV. For this array, the spectral shape was consistent with theory, and the branching ratio was determined to be 0.00582 $\\pm$ 0.00023 [stat] $\\pm$ 0.00062 [syst]. We report the first precision test of the shape of the photon energy spectrum from neutron radiative decay and a substantially improved determination of the branching ratio over a broad range of photon energies.

  7. Membrane solubilization in erythrocytes as a measure of radiation exposure to fast neutrons

    Science.gov (United States)

    Soltan Monem, A.; Ali, Fadel M.; Al-thani, Noura J. J.; Ali, Samira A.

    1999-02-01

    Membrane solubilization and osmotic fragility of rat erythrocytes irradiated in vivo with fast neutron fluences ranging from to using a source were measured instantaneously using a light scattering technique. The solubilization of erythrocyte membrane by a non-ionic detergent, octylglucoside (OG), was found to exhibit a two stage transition from vesicular form to mixed micellar form in the range of detergent concentrations 1.5-7.8 mM. The coexistence phase, vesicular/mixed micellar, was shifted towards higher detergent concentrations with increase in the neutron fluence, indicating increasing membrane resistance to the detergent and hence change in the natural membrane permeation properties. The technique shows an adequate sensitivity in detecting membrane damage in erythrocytes and has potential as a biophysical marker of radiation exposure. The osmotic fragility of irradiated erythrocytes shows a decreasing trend with increasing irradiation fluence measured directly and two weeks post-irradiation. Blood films photographed two weeks post-irradiation show developed elliptocytosis and crenated cell anaemia.

  8. Lattice Boltzmann solution of the transient Boltzmann transport equation in radiative and neutron transport.

    Science.gov (United States)

    Wang, Yahui; Yan, Liming; Ma, Yu

    2017-06-01

    Applications of the transient Boltzmann transport equation (BTE) have undergone much investigation, such as radiative heat transfer and neutron transport. This paper provides a lattice Boltzmann model to efficiently resolve the multidimensional transient BTE. For a higher angular resolution, enough transport directions are considered while the transient BTE in each direction is treated as a conservation law equation and solved independently. Both macroscopic equations recovered from a Chapman-Enskog expansion and simulated results of typical benchmark problems show not only the second-order accuracy but also the flexibility and applicability of the proposed lattice Boltzmann model. This approach may contribute a powerful technique for the parallel simulation of large-scale engineering and some alternative perspectives for solving the nonlinear transport problem further.

  9. Importance of Compton scattering to radiation spectra of isolated neutron stars

    CERN Document Server

    Suleimanov, V

    2006-01-01

    Model atmospheres of isolated neutron stars with low magnetic field are calculated with Compton scattering taking into account. Models with effective temperatures 1, 3 and 5 MK, with two values of surface gravity log(g)g = 13.9 and 14.3), and different chemical compositions are calculated. Radiation spectra computed with Compton scattering are softer than the computed with Thomson scattering at high energies (E > 5 keV) for hot (T_eff > 1 MK) atmospheres with hydrogen-helium composition. Compton scattering is more significant to hydrogen models with low surface gravity. The emergent spectra of the hottest (T_eff > 3 MK) model atmospheres can be described by diluted blackbody spectra with hardness factors ~ 1.6 - 1.9. Compton scattering is less important for models with solar abundance of heavy elements.

  10. Radiation Damage and Recovery in Neutron-Irradiated MgO Crystal

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    MgO single crystal was irradiated by neutron up to a dose of 5.74×1018 cm-2. The radiation damage and its recovery were studied by means of UV-VIS and EM spectroscopy. The results indicate that the irradiation generates large amount of optically detectable defects such as single anion vacancies (F+ center), anion divacancies (F2) and some higher order defects. Through isochronal annealing, these defects started a series of processes of diminishing and transforming, and finally all disappeared while annealing at 900 ℃. It seems that the absorption bands of 573 nm are resulted from a higher order and more complex aggregated center than that of 424, 451 nm bands.

  11. Simulating the displacement effect in electronics exposed to space radiation by fission and 14 MeV neutrons; Simulation de l'effet ''deplacement d'atome'' dans l'electronique soumise au rayonnement spatial, par des neutrons de fission et des neutrons de 14 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Zyromski, Ph. [CEA Valduc, Dept. Recherche sur les Materiaux Nucleaires, 21 - Is-sur-Tille (France)

    1999-07-01

    Various spatial radiation inducing displacement effect in the on board electronics may be quantified by a 1 MeV (Si) equivalent neutron fluence. Simulating this effect is made easier by using the PROSPERO reactor (fission neutrons) or the SAMES 400 kV accelerator (14 MeV neutrons) which data are recalled. (author)

  12. Radiation damage in InGaAs photodiodes by 1 MeV fast neutrons

    CERN Document Server

    Ohyama, H; Vanhellemont, J; Takami, Y; Sunaga, H

    1998-01-01

    Irradiation damage in In sub 0 sub . sub 5 sub 3 Ga sub 0 sub . sub 4 sub 7 As p-i-n photodiodes by 1 MeV fast neutrons has been studied as a function of fluence for the first time, and the results are discussed in this paper. The degradation of the electrical and optical performance of diodes increases with increasing fluence. The induced lattice defects in the In sub 0 sub . sub 5 sub 3 Ga sub 0 sub . sub 4 sub 7 As epitaxial layers and the InP substrate are studied by Deep Level Transient Spectroscopy (DLTS) methods. In the In sub 0 sub . sub 5 sub 3 Ga sub 0 sub . sub 4 sub 7 As epitaxial layers, hole and electron capture levels are induced by irradiation. The influence of the type of radiation source on the device degradation is then discussed by comparison to 1 MeV electrons with respect to the numbers of knock-on atoms and the nonionizing energy loss (NIEL). The radiation source dependence of performance degradation is attributed to the difference of mass between the two irradiating particles and the p...

  13. Radiation-induced carcinogenesis: mechanistically based differences between gamma-rays and neutrons, and interactions with DMBA.

    Directory of Open Access Journals (Sweden)

    Igor Shuryak

    Full Text Available Different types of ionizing radiation produce different dependences of cancer risk on radiation dose/dose rate. Sparsely ionizing radiation (e.g. γ-rays generally produces linear or upwardly curving dose responses at low doses, and the risk decreases when the dose rate is reduced (direct dose rate effect. Densely ionizing radiation (e.g. neutrons often produces downwardly curving dose responses, where the risk initially grows with dose, but eventually stabilizes or decreases. When the dose rate is reduced, the risk increases (inverse dose rate effect. These qualitative differences suggest qualitative differences in carcinogenesis mechanisms. We hypothesize that the dominant mechanism for induction of many solid cancers by sparsely ionizing radiation is initiation of stem cells to a pre-malignant state, but for densely ionizing radiation the dominant mechanism is radiation-bystander-effect mediated promotion of already pre-malignant cell clone growth. Here we present a mathematical model based on these assumptions and test it using data on the incidence of dysplastic growths and tumors in the mammary glands of mice exposed to high or low dose rates of γ-rays and neutrons, either with or without pre-treatment with the chemical carcinogen 7,12-dimethylbenz-alpha-anthracene (DMBA. The model provides a mechanistic and quantitative explanation which is consistent with the data and may provide useful insight into human carcinogenesis.

  14. Radiation-induced carcinogenesis: mechanistically based differences between gamma-rays and neutrons, and interactions with DMBA.

    Science.gov (United States)

    Shuryak, Igor; Brenner, David J; Ullrich, Robert L

    2011-01-01

    Different types of ionizing radiation produce different dependences of cancer risk on radiation dose/dose rate. Sparsely ionizing radiation (e.g. γ-rays) generally produces linear or upwardly curving dose responses at low doses, and the risk decreases when the dose rate is reduced (direct dose rate effect). Densely ionizing radiation (e.g. neutrons) often produces downwardly curving dose responses, where the risk initially grows with dose, but eventually stabilizes or decreases. When the dose rate is reduced, the risk increases (inverse dose rate effect). These qualitative differences suggest qualitative differences in carcinogenesis mechanisms. We hypothesize that the dominant mechanism for induction of many solid cancers by sparsely ionizing radiation is initiation of stem cells to a pre-malignant state, but for densely ionizing radiation the dominant mechanism is radiation-bystander-effect mediated promotion of already pre-malignant cell clone growth. Here we present a mathematical model based on these assumptions and test it using data on the incidence of dysplastic growths and tumors in the mammary glands of mice exposed to high or low dose rates of γ-rays and neutrons, either with or without pre-treatment with the chemical carcinogen 7,12-dimethylbenz-alpha-anthracene (DMBA). The model provides a mechanistic and quantitative explanation which is consistent with the data and may provide useful insight into human carcinogenesis.

  15. Neutron induced radiation damage of plastic scintillators for the upgrade of the Tile Calorimeter of the ATLAS detector.

    Science.gov (United States)

    Mdhluli, J. E.; Jivan, H.; Erasmus, R.; Davydov, Yu I.; Baranov, V.; Mthembu, S.; Mellado, B.; Sideras-Haddad, E.; Solovyanov, O.; Sandrock, C.; Peter, G.; Tlou, S.; Khanye, N.; Tjale, B.

    2017-07-01

    With the prediction that the plastic scintillators in the gap region of the Tile Calorimeter will sustain a significantly large amount of radiation damage during the HL-LHC run time, the current plastic scintillators will need to be replaced during the phase 2 upgrade in 2018. The scintillators in the gap region were exposed to a radiation environment of up to 10 kGy/year during the first run of data taking and with the luminosity being increased by a factor of 10, the radiation environment will be extremely harsh. We report on the radiation damage to the optical properties of plastic scintillators following irradiation using a neutron beam of the IBR-2 pulsed reactor in Joint Institute for Nuclear Research (JINR), Dubna. A comparison is drawn between polyvinyl toluene based commercial scintillators EJ200, EJ208 and EJ260 as well as polystyrene based scintillator from Kharkov. The samples were subjected to irradiation with high energy neutrons and a flux density range of 1 × 106-7.7 × 106. Light transmission, Raman spectroscopy, fluorescence spectroscopy and light yield testing was performed to characterize the damage induced in the samples. Preliminary results from the tests done indicate a minute change in the optical properties of the scintillators with further studies underway to gain a better understanding of the interaction between neutrons with plastic scintillators.

  16. Intercomparison of radiation protection devices in a high-energy stray neutron field. Part III: Instrument response

    CERN Document Server

    Silari, M; Beck, P; Bedogni, R; Cale, E; Caresana, M; Domingo, C; Donadille, L; Dubourg, N; Esposito, A; Fehrenbacher, G; Fernández, F; Ferrarini, M; Fiechtner, A; Fuchs, A; García, M J; Golnik, N; Gutermuth, F; Khurana, S; Klages, Th; Latocha, M; Mares, V; Mayer, S; Radon, T; Reithmeier, H; Rollet, S; Roos, H; Rühm, W; Sandri, S; Schardt, D; Simmer, G; Spurný, F; Trompier, F; Villa-Grasa, C; Weitzenegger, E; Wiegel, B; Wielunski, M; Wissmann, F; Zechner, A; Zielczyński, M

    2009-01-01

    The European Commission has funded within its 6th Framework Programme a three-year project (2005–2007) called CONRAD, COordinated Network for RAdiation Dosimetry. The organizational framework for this project was provided by the European radiation Dosimetry Group EURADOS. Work Package 6 of CONRAD dealt with “complex mixed radiation fields at workplaces” and in this context it organised a benchmark exercise, which included both measurements and calculations, in a stray radiation field at a high-energy particle accelerator at GSI, Germany. The aim was to intercompare the response of several types of active detectors and passive dosemeters in a well-characterised workplace field. The Monte Carlo simulations of the radiation field and the experimental determination of the neutron spectra with various Bonner Sphere Spectrometers are discussed in Rollet et al. (2008) and in Wiegel et al. (2008). This paper focuses on the intercomparison of the response of the dosemeters in terms of ambient dose equivalent. Th...

  17. Analysis of radiation environmental safety for China's Spallation Neutron Source (CSNS)

    Science.gov (United States)

    Wang, Qing-Bin; Wu, Qing-Biao; Ma, Zhong-Jian; Zhang, Qing-Jiang; Li, Nan; Wu, Jing-Min; Liu, Jian; Zhang, Gang

    2010-07-01

    The China Spallation Neutron Source (CSNS) is going to be located in Dalang Town, Dongguan City in the Guangdong Province. In this paper we report the results of the parameters related with environment safety based on experiential calculations and Monte Carlo simulations. The main project of the accelerator is an under ground construction. On top there is a 0.5 m concrete and 5.0 m soil covering for shielding, which can reduce the dose out of the tunnel's top down to 0.2 μSv/h. For the residents on the boundary of the CSNS, the dose produced by skyshine, which is caused by the penetrated radiation leaking from the top of the accelerator, is no more than 0.68 μSv/a. When CSNS is operating normally, the maximal annual effective dose due to the emission of gas from the tunnel is 2.40×10-3 mSv/a to the public adult, and 2.29×10-3 mSv/a to a child, both values are two orders of magnitude less than the limiting value for control and management. CSNS may give rise to an activation of the soil and groundwater in the nearest tunnels, where the main productions are 3H, 7Be, 22Na, 54Mn, etc. But the specific activity is less than the exempt specific activity in the national standard GB13376-92. So it is safe to say that the environmental impact caused by the activation of soil and groundwater is insignificant. To sum up, for CSNS, as a powerful neutron source device, driven by a high-energy high-current proton accelerator, a lot of potential factors affecting the environment exist. However, as long as effective shieldings for protection are adopted and strict rules are drafted, the environmental impact can be kept under control within the limits of the national standard.

  18. Research with neutron and synchrotron radiation on aerospace and automotive materials and components

    Energy Technology Data Exchange (ETDEWEB)

    Kaysser, Wolfgang; Abetz, Volker; Huber, Norbert; Kainer, Karl Ulrich; Pyczak, Florian; Schreyer, Andreas; Staron, Peter [Helmholtz-Zentrum Geesthacht Zentrum fuer Material und Kuestenforschung, Geesthacht (Germany); Esslinger, Joerg [MTU Aero Engines GmbH, Muenchen (Germany); Klassen, Thomas [Helmholtz-Zentrum Geesthacht Zentrum fuer Material und Kuestenforschung, Geesthacht (Germany); Helmut Schmidt Universitaet, Hamburg (Germany)

    2011-08-15

    Characterization with neutrons and synchrotron radiation has yielded essential contributions to the research and development of automotive and aerospace materials, processing methods, and components. This review mainly emphasises developments related to commercial passenger airplanes and light-duty cars. Improved and partly new materials for the reduction of airframe weight and joining by laser-beam welding and friction stir welding are ongoing areas of assessment. Chemical reactions, microstructure development, and residual stresses are frequently measured. Polymers and polymer matrix composites often require special experimental techniques. The thrust-to-weight ratio of aero-engines is increasing due to the improved design of components and the use of innovative materials. Investigations on superalloys, {gamma}-TiAl, and thermal barrier coatings are described in some detail. A discussion of the use of neutron and synchrotron diffraction in automotive applications covers the analysis of surface effects with respect to lubricants and wear, as well as the investigation of microstructure development, deformation, and fatigue behavior of materials, welds and components. Special steels, Al and Mg alloys are discussed and residual stresses in automotive components such as gears or crankshafts are described. Applications of characterization methods on membranes for polymeric membrane fuel cells and on nanocrystalline metal hydrides for hydrogen storage are shown. The degradation of railway tracks after long-term use is taken as an example for the application of synchrotron methods to transport systems beyond the commercial aircraft and light duty passenger car. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Response of neutron dosemeters in radiation protection environments: an investigation of techniques to improve estimates of dose equivalent

    Energy Technology Data Exchange (ETDEWEB)

    Naismith, O.F.; Thomas, D.J. [National Physical Lab., Teddington (United Kingdom); Siebert, B.R.L. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    1997-09-01

    The response of practicable neutron dosemeters for routine use generally does not match the conversion function from fluence for radiation protection quantities such as the ambient dose equivalent. As a consequence, significant errors may be encountered when monitoring in a neutron energy spectrum different from that in which the dosemeter was calibrated, which is almost inevitably the case. A database of neutron energy spectra, detector response functions, and dosimetric conversion factors has been developed, and has been used to investigate the extent of this problem. The paper examines various ways of improving dosemeter response by `ranking` spectra and deriving correction factors based upon this ordering. In the case of area monitoring, a combination of two responses (e.g. a rem meter and TEPC) may serve to improve the measurement of dose equivalent. (author).

  20. Monte-Carlo Simulations of Radiation-Induced Activation in a Fast-Neutron and Gamma- Based Cargo Inspection System

    CERN Document Server

    Bromberger, B; Brandis, M; Dangendorf, V; Goldberg, M B; Kaufmann, F; Mor, I; Nolte, R; Schmiedel, M; Tittelmeier, K; Vartsky, D; Wershofen, H

    2012-01-01

    An air cargo inspection system combining two nuclear reaction based techniques, namely Fast-Neutron Resonance Radiography and Dual-Discrete-Energy Gamma Radiography is currently being developed. This system is expected to allow detection of standard and improvised explosives as well as special nuclear materials. An important aspect for the applicability of nuclear techniques in an airport inspection facility is the inventory and lifetimes of radioactive isotopes produced by the neutron and gamma radiation inside the cargo, as well as the dose delivered by these isotopes to people in contact with the cargo during and following the interrogation procedure. Using MCNPX and CINDER90 we have calculated the activation levels for several typical inspection scenarios. One example is the activation of various metal samples embedded in a cotton-filled container. To validate the simulation results, a benchmark experiment was performed, in which metal samples were activated by fast-neutrons in a water-filled glass jar. T...

  1. BOOK REVIEW: Analysis of Residual Stress by Diffraction Using Neutron and Synchrotron Radiation

    Science.gov (United States)

    Fitzpatrick, ed M. E.; Lodini, A.

    2003-09-01

    The presence of residual stresses within engineering components is often a key feature in determining their usable lifetimes and failure characteristics. Residual surface compression can, for example, restrict the propagation of surface cracks through the bulk. As a consequence, it is essential to characterize the magnitude and spatial distribution of residual stresses and, at least for non-destructive testing, this is most widely achieved using diffraction of neutron and high energy synchrotron radiations. This book aims to provide a detailed description of the methodology used to determine residual stresses. The major emphasis is placed on the neutron method, this being the more widely established approach at present. It contains 20 chapters contributed by 23 authors, divided into five major parts. The overall layout is very logical, with the first part giving a general introduction to the use of neutrons and x-rays for materials research and summarizing the methods used for their production. Part 2 considers the more specific aspects of extracting the residual stress distribution within a bulk sample and includes some valuable comments on a number of potential experimental problems, such as the determination of the stress-free lattice parameter and the effects of broadening of the Bragg peaks. The experimental facilities currently available or under development are described in part 3, with the remaining two parts devoted to general and specific applications of the residual stress measurement technique. As expected with such a large number of different authors, there is some variation in style and quality. However, the text is generally easy to follow and, more importantly, it is largely free of the problems of inconsistent notation and dupication of material that can afflict multi-authored texts. My only negative comment concerns the latter portion of the book devoted to specific applications of the technique, which is illustrative rather than comprehensive. In

  2. Experimental and numerical investigations of radiation characteristics of Russian portable/compact pulsed neutron generators: ING-031, ING-07, ING-06 and ING-10-20-120

    Energy Technology Data Exchange (ETDEWEB)

    Chernikova, D., E-mail: dina@nephy.chalmers.se [Chalmers University of Technology, Department of Applied Physics, Nuclear Engineering, Fysikgården 4, SE-412 96 Göteborg (Sweden); Romodanov, V.L.; Belevitin, A.G.; Afanas' ev, V.V.; Sakharov, V.K. [National Nuclear Research University/Moscow Engineering-Physics Institute (NIYaU MIFI), Moscow (Russian Federation); Bogolubov, E.P.; Ryzhkov, V.I.; Khasaev, T.O.; Sladkov, A.A.; Bitulev, A.A. [Dukhov All-Russia Research Institute of Automatics (VNIIA), Moscow (Russian Federation)

    2014-05-11

    The present paper discusses results of full-scale experimental and numerical investigations of influence of construction materials of portable pulsed neutron generators ING-031, ING-07, ING-06 and ING-10-20-120 (VNIIA, Russia) to their radiation characteristics formed during and after an operation (shutdown period). In particular, it is shown that an original monoenergetic isotropic angular distribution of neutrons emitted by TiT target changes into the significantly anisotropic angular distribution with a broad energy spectrum stretching to the thermal region. Along with the low-energetic neutron part, a significant amount of photons appears during the operation of generators. In the pulse mode of operation of neutron generator, a presence of the construction materials leads to the “tailing” of the original neutron pulse and the appearance of an accompanying photon pulse at ∼3ns after the instant neutron pulse. In addition to that, reactions of neutron capture and inelastic scattering lead to the creation of radioactive nuclides, such as {sup 58}Co, {sup 62}Cu, {sup 64}Cu and {sup 18}F, which form the so-called activation radiation. Thus, the selection of a portable neutron generator for a particular type of application has to be done considering radiation characteristics of the generator itself. This paper will be of interest to users of neutron generators, providing them with valuable information about limitations of a specific generator and with recommendations for improving the design and performance of the generator as a whole.

  3. Neutron Radiation Tolerance of Two Benchmark Thiophene-Based Conjugated Polymers: the Importance of Crystallinity for Organic Avionics

    Science.gov (United States)

    Paternò, G. M.; Robbiano, V.; Fraser, K. J.; Frost, C.; García Sakai, V.; Cacialli, F.

    2017-01-01

    Aviation and space applications can benefit significantly from lightweight organic electronics, now spanning from displays to logics, because of the vital importance of minimising payload (size and mass). It is thus crucial to assess the damage caused to such materials by cosmic rays and neutrons, which pose a variety of hazards through atomic displacements following neutron-nucleus collisions. Here we report the first study of the neutron radiation tolerance of two poly(thiophene)s-based organic semiconductors: poly(3-hexylthiophene-2,5-diyl), P3HT, and the liquid-crystalline poly(2,5-bis (3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT. We combine spectroscopic investigations with characterisation of intrinsic charge mobility to show that PBTTT exhibits significantly higher tolerance than P3HT. We explain this in terms of a superior chemical, structural and conformational stability of PBTTT, which can be ascribed to its higher crystallinity, in turn induced by a combination of molecular design features. Our approach can be used to develop design strategies for better neutron radiation-tolerant materials, thus paving the way for organic semiconductors to enter avionics and space applications. PMID:28112195

  4. Neutron Radiation Tolerance of Two Benchmark Thiophene-Based Conjugated Polymers: the Importance of Crystallinity for Organic Avionics

    Science.gov (United States)

    Paternò, G. M.; Robbiano, V.; Fraser, K. J.; Frost, C.; García Sakai, V.; Cacialli, F.

    2017-01-01

    Aviation and space applications can benefit significantly from lightweight organic electronics, now spanning from displays to logics, because of the vital importance of minimising payload (size and mass). It is thus crucial to assess the damage caused to such materials by cosmic rays and neutrons, which pose a variety of hazards through atomic displacements following neutron-nucleus collisions. Here we report the first study of the neutron radiation tolerance of two poly(thiophene)s-based organic semiconductors: poly(3-hexylthiophene-2,5-diyl), P3HT, and the liquid-crystalline poly(2,5-bis (3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT. We combine spectroscopic investigations with characterisation of intrinsic charge mobility to show that PBTTT exhibits significantly higher tolerance than P3HT. We explain this in terms of a superior chemical, structural and conformational stability of PBTTT, which can be ascribed to its higher crystallinity, in turn induced by a combination of molecular design features. Our approach can be used to develop design strategies for better neutron radiation-tolerant materials, thus paving the way for organic semiconductors to enter avionics and space applications.

  5. Gantry orientation effect on the neutron and capture gamma ray dose equivalent at the maze entrance door in radiation therapy

    Directory of Open Access Journals (Sweden)

    Ghiasi Hosein

    2012-01-01

    Full Text Available In the present study, the effect of gantry orientation on the photoneutron and capture gamma dose calculations for maze entrance door was evaluated. A typical radiation therapy room made of ordinary concrete was simulated using MCNPX Monte Carlo code. Gantry rotation was simulated at eight different angles around the isocenter. Both neutron and capture gamma dose vary considerably with gantry angle. The ratios of the maximum to the minimum values for neutron and capture gamma dose equivalents were 1.9 and 1.4, respectively. On the other hand, comparison of the Monte Carlo calculated mean value over all orientations with Monte Carlo calculated neutron and gamma dose showed that the Wu-McGinley method differed by 5% and 2%, respectively. However, for more conservative shielding calculations, factors of 1.6 and 1.3 should be applied to the calculated neutron and capture gamma doses at downward irradiation. Finally, it can be concluded that the gantry angle influences neutron and capture gamma dose at the maze entrance door and it should be taken into account in shielding considerations.

  6. Neutronics experiments, radiation detectors and nuclear techniques development in the EU in support of the TBM design for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Angelone, M., E-mail: maurizio.angelone@enea.it [ENEA UT-FUS C.R. Frascati, via E. Fermi, 45-00044 Frascati (Italy); Fischer, U. [Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Flammini, D. [ENEA UT-FUS C.R. Frascati, via E. Fermi, 45-00044 Frascati (Italy); Jodlowski, P. [AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Klix, A. [Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Kodeli, I. [Jožef Stefan Institute, Ljubljana (Slovenia); Kuc, T. [AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Leichtle, D. [Fusion for Energy, C/Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Lilley, S. [Culham Centre for Fusion Energy, Culham, OX14 3DB (United Kingdom); Majerle, M.; Novák, J. [Nuclear Physics Institute of the ASCR, Řež 130, 250 68 Řež (Czech Republic); Ostachowicz, B. [AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Packer, L.W. [Culham Centre for Fusion Energy, Culham, OX14 3DB (United Kingdom); Pillon, M. [ENEA UT-FUS C.R. Frascati, via E. Fermi, 45-00044 Frascati (Italy); Pohorecki, W. [AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Radulović, V. [Jožef Stefan Institute, Ljubljana (Slovenia); Šimečková, E. [Nuclear Physics Institute of the ASCR, Řež 130, 250 68 Řež (Czech Republic); and others

    2015-10-15

    Highlights: • A number of experiments and tests are ongoing to develop detectors and methods for HCLL and HCPM ITER-TBM. • Experiments for measuring gas production relevant to IFMIF are also performed using a cyclotron. • A benchmark experiment with a Cu block is performed to validate copper cross sections. • Experimental techniques to measure tritium in TBM are presented. • Experimental verification of activation cross sections for a Neutron Activation System for TBM is addressed. - Abstract: The development of high quality nuclear data, radiation detectors and instrumentation techniques for fusion technology applications in Europe is supported by Fusion for Energy (F4E) and conducted in a joint and collaborative effort by several European research associations (ENEA, KIT, JSI, NPI, AGH, and CCFE) joined to form the “Consortium on Nuclear Data Studies/Experiments in Support of TBM Activities”. This paper presents the neutronics activities carried out by the Consortium. A selection of available results are presented. Among then a benchmark experiment on a pure copper block to study the Cu cross sections at neutron energies relevant to fusion, the fabrication of prototype neutron detectors able to withstand harsh environment and temperature >200 °C (artificial diamond and self-powered detectors) developed for operating in ITER-TBM as well as measurement of relevant activation and integral gas production cross-sections. The latter measured at neutron energies relevant to IFMIF (>14 MeV) and the development of innovative experimental techniques for tritium measurement in TBM.

  7. Using FLUKA to Study Concrete Square Shield Performance in Attenuation of Neutron Radiation Produced by APF Plasma Focus Neutron Source

    Science.gov (United States)

    Nemati, M. J.; Habibi, M.; Amrollahi, R.

    2013-04-01

    In 2010, representatives from the Nuclear Engineering and physics Department of Amirkabir University of Technology (AUT) requested development of a project with the objective of determining the performance of a concrete shield for their Plasma Focus as neutron source. The project team in Laboratory of Nuclear Engineering and physics department of Amirkabir University of Technology choose some shape of shield to study on their performance with Monte Carlo code. In the present work, the capability of Monte Carlo code FLUKA will be explored to model the APF Plasma Focus, and investigating the neutron fluence on the square concrete shield in each region of problem. The physical models embedded in FLUKA are mentioned, as well as examples of benchmarking against future experimental data. As a result of this study suitable thickness of concrete for shielding APF will be considered.

  8. High-dose neutron induced radiation swelling simulated by heavy ion irradiation and its microscopic study with positron annihilation technique

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    70 MeV-carbon-ion irradiation is used to simulate the radiation swelling induced by neutron irradiation of 3.2×1022 n·cm-2 in domestically-made 316 austenitic stainless steels modified by a 20%-cold-working and Ti-adding from room temperature to 802°C. The created swelling is microscopically examined by the positron annihilation lifetime technique. A radiation swelling peak is observed at 580°C and the corresponding void has an average diameter of 0.7nm which is hardly probed by macroscopic methods.

  9. From radiation-induced chromosome damage to cell death: modelling basic mechanisms and applications to boron neutron capture therapy.

    Science.gov (United States)

    Ballarini, F; Bortolussi, S; Clerici, A M; Ferrari, C; Protti, N; Altieri, S

    2011-02-01

    Cell death is a crucial endpoint in radiation-induced biological damage: on one side, cell death is a reference endpoint to characterise the action of radiation in biological targets; on the other side, any cancer therapy aims to kill tumour cells. Starting from Lea's target theory, many models have been proposed to interpret radiation-induced cell killing; after briefly discussing some of these models, in this paper, a mechanistic approach based on an experimentally observed link between chromosome aberrations and cell death was presented. More specifically, a model and a Monte Carlo code originally developed for chromosome aberrations were extended to simulate radiation-induced cell death applying an experimentally observed one-to-one relationship between the average number of 'lethal aberrations' (dicentrics, rings and deletions) per cell and -ln S, S being the fraction of surviving cells. Although such observation was related to X rays, in the present work, the approach was also applied to protons and alpha particles. A good agreement between simulation outcomes and literature data provided a model validation for different radiation types. The same approach was then successfully applied to simulate the survival of cells enriched with boron and irradiated with thermal neutrons at the Triga Mark II reactor in Pavia, to mimic a typical treatment for boron neutron capture therapy.

  10. Radiolytic yield of ozone in air for low dose neutron and x-ray/gamma-ray radiation

    Science.gov (United States)

    Cole, J.; Su, S.; Blakeley, R. E.; Koonath, P.; Hecht, A. A.

    2015-01-01

    Radiation ionizes surrounding air and produces molecular species, and these localized effects may be used as a signature of, and for quantification of, radiation. Low-level ozone production measurements from radioactive sources have been performed in this work to understand radiation chemical yields at low doses. The University of New Mexico AGN-201 M reactor was used as a tunable radiation source. Ozone levels were compared between reactor-on and reactor-off conditions, and differences (0.61 to 0.73 ppb) well below background levels were measured. Simulations were performed to determine the dose rate distribution and average dose rate to the air sample within the reactor, giving 35 mGy of mixed photon and neutron dose. A radiation chemical yield for ozone of 6.5±0.8 molecules/100 eV was found by a variance weighted average of the data. The different contributions of photons and neutrons to radiolytic ozone production are discussed.

  11. Pulse-shape analysis for gamma background rejection in thermal neutron radiation using CVD diamond detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kavrigin, P., E-mail: pavel.kavrigin@cividec.at [Vienna University of Technology (Austria); Finocchiaro, P., E-mail: finocchiaro@lns.infn.it [INFN Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Griesmayer, E., E-mail: erich.griesmayer@cividec.at [Vienna University of Technology (Austria); Jericha, E., E-mail: jericha@ati.ac.at [Vienna University of Technology (Austria); Pappalardo, A., E-mail: apappalardo@lns.infn.it [INFN Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Weiss, C., E-mail: Christina.Weiss@cern.ch [Vienna University of Technology (Austria); European Organisation for Nuclear Research (CERN), Geneva (Switzerland)

    2015-09-21

    A novel technique for the rejection of gamma background from charged-particle spectra was demonstrated using a CVD diamond detector with a {sup 6}Li neutron converter installed at a thermal neutron beamline of the TRIGA research reactor at the Atominstitut (Vienna University of Technology). Spectra of the alpha particles and tritons of {sup 6}Li(n,T){sup 4}He thermal neutron capture reaction were separated from the gamma background by a new algorithm based on pulse-shape analysis. The thermal neutron capture in {sup 6}Li is already used for neutron flux monitoring, but the ability to remove gamma background allows using a CVD diamond detector for thermal neutron counting. The pulse-shape analysis can equally be applied to all cases where the charged products of an interaction are absorbed in the diamond and to other background particles that fully traverse the detector.

  12. Neutron Radiation Tests about FeCr Slag and Natural Zeolite Loaded Brick Samples

    Directory of Open Access Journals (Sweden)

    Vedat Veli Cay

    2014-01-01

    Full Text Available Neutron shielding performances of new brick samples are investigated. Brick samples including 10, 20, and 30 percentages of ferrochromium slag (FeCr waste and natural zeolite are prepared and mechanical properties are obtained. Total macroscopic cross sections are calculated by using results of 4.5 MeV neutron transmission experiments. As a result, neutron shielding capacity of brick samples increases with increasing FeCr slag and natural zeolite percentages. This information could be useful in the area of neutron shielding.

  13. Neutron Resonance Data Exclude Random Matrix Theory

    CERN Document Server

    Koehler, P E; Krtička, M; Guber, K H; Ullmann, J L

    2012-01-01

    Almost since the time it was formulated, the overwhelming consensus has been that random matrix theory (RMT) is in excellent agreement with neutron resonance data. However, over the past few years, we have obtained new neutron-width data at Oak Ridge and Los Alamos National Laboratories that are in stark disagreement with this theory. We also have reanalyzed neutron widths in the most famous data set, the nuclear data ensemble (NDE), and found that it is seriously flawed, and, when analyzed carefully, excludes RMT with high confidence. More recently, we carefully examined energy spacings for these same resonances in the NDE using the $\\Delta_{3}$ statistic. We conclude that the data can be found to either confirm or refute the theory depending on which nuclides and whether known or suspected p-wave resonances are included in the analysis, in essence confirming results of our neutron-width analysis of the NDE. We also have examined radiation widths resulting from our Oak Ridge and Los Alamos measurements, and ...

  14. Neutron resonance data exclude random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Koehler, P.E. [Physics Division, Oak Ridge National Laboratory, MailStop 6356, Oak Ridge, Tennessee 37831 (United States); Becvar, F.; Krticka, M. [Charles University, Faculty of Mathematics and Physics, 180 00 Prague 8 (Czech Republic); Guber, K.H. [Reactor and Nuclear Systems Division, Oak Ridge National Laboratory, Mail Stop 6356, Oak Ridge, Tennessee 37831 (United States); Ullmann, J.L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2013-02-15

    Almost since the time it was formulated, the overwhelming consensus has been that random matrix theory (RMT) is in excellent agreement with neutron resonance data. However, over the past few years, we have obtained new neutron-width data at Oak Ridge and Los Alamos National Laboratories that are in stark disagreement with this theory. We also have reanalyzed neutron widths in the most famous data set, the nuclear data ensemble (NDE), and found that it is seriously flawed, and, when analyzed carefully, excludes RMT with high confidence. More recently, we carefully examined energy spacings for these same resonances in the NDE using the {Delta}{sub 3} statistic. We conclude that the data can be found to either confirm or refute the theory depending on which nuclides and whether known or suspected p-wave resonances are included in the analysis, in essence confirming results of our neutron-width analysis of the NDE. We also have examined radiation widths resulting from our Oak Ridge and Los Alamos measurements, and find that in some cases they do not agree with RMT. Although these disagreements presently are not understood, they could have broad impact on basic and applied nuclear physics, from nuclear astrophysics to nuclear criticality safety. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Neutron resonance data exclude random matrix theory

    Science.gov (United States)

    Koehler, P. E.; Bečvář, F.; Krtička, M.; Guber, K. H.; Ullmann, J. L.

    2013-02-01

    Almost since the time it was formulated, the overwhelming consensus has been that random matrix theory (RMT) is in excellent agreement with neutron resonance data. However, over the past few years, we have obtained new neutron-width data at Oak Ridge and Los Alamos National Laboratories that are in stark disagreement with this theory. We also have reanalyzed neutron widths in the most famous data set, the nuclear data ensemble (NDE), and found that it is seriously flawed, and, when analyzed carefully, excludes RMT with high confidence. More recently, we carefully examined energy spacings for these same resonances in the NDE using the $\\Delta_{3}$ statistic. We conclude that the data can be found to either confirm or refute the theory depending on which nuclides and whether known or suspected p-wave resonances are included in the analysis, in essence confirming results of our neutron-width analysis of the NDE. We also have examined radiation widths resulting from our Oak Ridge and Los Alamos measurements, and find that in some cases they do not agree with RMT. Although these disagreements presently are not understood, they could have broad impact on basic and applied nuclear physics, from nuclear astrophysics to nuclear criticality safety.

  16. An apparatus for the study of high temperature water radiolysis in a nuclear reactor: calibration of dose in a mixed neutron/gamma radiation field.

    Science.gov (United States)

    Edwards, Eric J; Wilson, Paul P H; Anderson, Mark H; Mezyk, Stephen P; Pimblott, Simon M; Bartels, David M

    2007-12-01

    The cooling water of nuclear reactors undergoes radiolytic decomposition induced by gamma, fast electron, and neutron radiation in the core. To model the process, recombination reaction rates and radiolytic yields for the water radical fragments need to be measured at high temperature and pressure. Yields for the action of neutron radiation are particularly hard to determine independently because of the beta/gamma field also present in any reactor. In this paper we report the design of an apparatus intended to measure neutron radiolysis yields as a function of temperature and pressure. A new methodology for separation of neutron and beta/gamma radiolysis yields in a mixed radiation field is proposed and demonstrated.

  17. Measuring Neutrons and Gamma Rays on Mars - The Mars Science Laboratory Radiation Assessment Detector MSL/RAD

    Science.gov (United States)

    Wimmer-Schweingruber, R. F.; Martin, C.; Kortmann, O.; Boehm, E.; Kharytonov, A.; Ehresmann, B.; Hassler, D. M.; Zeitlin, C.; Rad Team

    2010-12-01

    The Mars Science Laboratory (MSL) missions Radiation Assessment Detector (RAD) will measure the radiation environment on the Martian surface. One of the difficult measurements is that of the neutral radiation component consisting of neutrons and gamma rays. Different from Earth, this neutral component contributes substantially to the total dose on the planetary surface, principally because the Martian atmosphere is so thin. The RAD instrument is capable of measuring neutral particles through a combination of sensitive anti-coincidence and organic and inorganic scintillator materials. In this work, we will explain how RAD will measure the neutral particle radiation on Mars and compare with calibration results. The problem of inverting measured neutron and gamma data is a non-trivial task. For all inversions, one generally assumes that the measurement process can be described by a system of linear equations, A ěc{f} = ěc{z}, where the matrix A describes the instrument response function (IRF), ěc{f} the underlying, but unknown, ``real'' physical parameters, and ěc{z} the measured data. The inversion of this deceptively simple-looking set of equations is in fact a key example of an ill-posed or inverse problem. Such problems are notoriously difficult to solve.

  18. Properties of Neutrino-driven Ejecta from the Remnant of a Binary Neutron Star Merger: Pure Radiation Hydrodynamics Case

    Science.gov (United States)

    Fujibayashi, Sho; Sekiguchi, Yuichiro; Kiuchi, Kenta; Shibata, Masaru

    2017-09-01

    We performed general relativistic, long-term, axisymmetric neutrino radiation hydrodynamics simulations for the remnant formed after a binary neutron star merger, which consists of a massive neutron star and a torus surrounding it. As an initial condition, we employ the result derived in a three-dimensional, numerical relativity simulation for the binary neutron star merger. We investigate the properties of neutrino-driven ejecta. Due to the pair-annihilation heating, the dynamics of the neutrino-driven ejecta are significantly modified. The kinetic energy of the ejecta is about two times larger than that in the absence of pair-annihilation heating. This suggests that the pair-annihilation heating plays an important role in the evolution of merger remnants. The relativistic outflow, which is required for driving gamma-ray bursts, is not observed because the specific heating rate around the rotational axis is not sufficiently high, due to the baryon loading caused by the neutrino-driven ejecta from the massive neutron star. We discuss the condition for launching the relativistic outflow and the nucleosynthesis in the ejecta.

  19. Investigation of Neutron Radiation Effects on Polyclonal Antibodies (IgG) and Fluorescein Dye for Astrobiological Applications

    Science.gov (United States)

    Le Postollec, A.; Coussot, G.; Baqué, M.; Incerti, S.; Desvignes, I.; Moretto, P.; Dobrijevic, M.; Vandenabeele-Trambouze, O.

    2009-09-01

    Detecting life in the Solar System is one of the great challenges of new upcoming space missions. Biochips have been proposed as a way to detect organic matter on extraterrestrial objects. A biochip is a miniaturized device composed of biologically sensitive systems, such as antibodies, which are immobilized on a slide. In the case of in situ measurements, the main concern is to ensure the survival of the antibodies under space radiation. Our recent computing simulation of cosmic ray interactions with the martian environment shows that neutrons are one of the dominant species at soil level. Therefore, we have chosen, in a first approach, to study antibody resistance to neutrons by performing irradiation experiments at the Applications Interdisciplinaires des Faisceaux d'Ions en Région Aquitaine (AIFIRA) platform, a French ion beam facility at the Centre d'Etudes Nucléaires de Bordeaux-Gradignan in Bordeaux. Antibodies and fluorescent dyes, freeze-dried and in buffer solution, were irradiated with 0.6 MeV and 6 MeV neutrons. Sample analyses demonstrated that, in the conditions tested, antibody recognition capability and fluorescence dye intensity are not affected by the neutrons.

  20. Promising cancer treatment modality: the University of California Davis/McClellan Nuclear Radiation Center neutron capture therapy program

    Science.gov (United States)

    Autry-Conwell, Susan A.; Boggan, James E.; Edwards, Benjamin F.; Hou, Yongjin; Vincente, Maria-Graca; Liu, Hungyuan; Richards, Wade J.

    2000-12-01

    Neutron capture therapy (NCT) is a promising new binary therapeutic modality for the treatment of localized tumors. It is accomplished by injection and localization within the tumor of a neutron capture agent (NCA) that alone, is non- toxic. Whenthe tumor is then exposed to neutrons, a relatively non-toxic form of radiation, crytotoxic products are produced that directly or indirectly cause tumor cell death, and yet preserves normal surrounding tissue not contain the NCA. The UC Davis NCT program is currently working to develop and test new compounds or NCA in vitro and in vivo. Many groups worldwide are also working to develop the next generation NCA, but less than five facilities internationally are currently capable to treating clinical brain tumor patients by NCT and only two US facilities, MIT and Brookhaven National Laboratory. In addition to compound development, the UC Davis NCT program is preparing the UC Davis McClellan Nuclear Radiation Center's 2 megawatt TRIGA reactor for NCT clinical trials which would make it the only such facility on the West Coast.

  1. Axial and radial preliminary results of the neutron radiation from miniature plasma focus devices

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, J.; Silva, P.; Soto, L. [Comision Chilena de Energia Nuclear, Santiago (Chile)

    2004-07-01

    As first step of a program to design a repetitive pulsed neutron generator for applications, two miniature plasma foci have been designed and constructed at the Chilean commission of nuclear energy. The devices operate at an energy level of the order of tens of joules (PF-50 J, 160 nF capacitor bank, 20-35 kV, 32-100 J, {approx} 150 ns time to peak current) and hundred of joules (PF-400 J, 880 nF, 20-35 kV, 176-539 J, {approx} 300 ns time to peak current). Neutron emission has been obtained in both devices operating in deuterium. A specific technique was necessary to develop in order to detect neutron pulsed of 10{sup 4} neutrons per shot. The maximum total neutron yield measured was of the order of 10{sup 6} and 10{sup 4} neutrons per shot in the PF-400 J and PF-50 J respectively. Axial and radial measurements of the neutron emission are presented and the anisotropy is evaluated in this work. The neutrons are measured by pairs of silver activation counters, {sup 3}He detectors and scintillator-photomultiplier detectors. (authors)

  2. 78 FR 21567 - Installation of Radiation Alarms for Rooms Housing Neutron Sources

    Science.gov (United States)

    2013-04-11

    ... Materials and Environmental Management Programs, U.S. Nuclear Regulatory Commission, Washington, DC 20555... and spallation sources. Neutron sources are used in diverse applications in areas of physics... for on-the-spot analysis, and to detect ground water movement for environmental surveys. Neutron...

  3. Measurement of Neutron Field Characteristics at Nuclear-Physics Instalations for Personal Radiation Monitoring

    CERN Document Server

    Alekseev, A G; Britvich, G I; Kosyanenko, E V; Pikalov, V A; Gomonov, I P

    2003-01-01

    n this work the observed data of neutron spectra on Rostov NEP, Kursk NEP and Smolensk NEP and on the reactor IRT MIPHI are submitted. For measurement of neutron spectra two types of spectrometer were used: SHANS (IHEP design ) and SDN-MS01 (FEI design). The comparison of the data measurements per-formed by those spectrometers above one-type cells on the reactor RBMK is submitted. On the basis of the 1-st horizontal experimental channel HEC-1 of the IRT reactor 4 reference fields of neutrons are investigated. It is shown, that spectra of neutrons of reference fields can be used for imitation of neutron spectra for conditions of NEP with VVER and RBMK type reactors.

  4. Evaluation of area monitor response for neutrons in radiation field generated by a 15 MV clinic accelerator; Avaliacao da resposta dos monitores de area para neutrons em campo de radiacao gerado por um acelerador clinico de 15 MV

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, Ana Paula

    2011-07-01

    The clinical importance and usage of linear accelerators in cancer treatment increased significantly in the last years. Coupled with this growth came the concern about the use of accelerators with energies over to 10 MeV which produce therapeutic beam contaminated with neutrons generated when high-energy photons interact with high-atomic-number materials such as tungsten and lead present in the accelerator itself. At these facilities, measurements of the ambient dose equivalent for neutrons present difficulties owing to the existence of a mixed radiation field and possible electromagnetic interference near the accelerator. The Neutron Laboratory of the IRD - Brazilian Institute for Radioprotection and Dosimetry, aiming to evaluate the survey meters performance at these facilities, initiated studies of instrumentation response in the presence of different neutron spectra. Neutrons sources with average energies ranging from 0.55 to 4.2 MeV, four different survey meters and one ionization chamber to obtain the ratio between the dose due to neutrons and gamma radiation were used in this work. The evaluation of these measurements, performed in a 15 MV linear accelerator room is presented. This work presents results that demonstrate the complexity and care needed to make neutrons measurements in radiotherapy treatment rooms containing high energy clinical accelerators. (author)

  5. Dense Plasma Focus as Collimated Source of D-D Fusion Neutron Beams for Irradiation Experiences and Study of Emitted Radiations

    Science.gov (United States)

    Milanese, M.; Niedbalski, J.; Moroso, R.; Guichón, S.; Supán, J.

    2008-04-01

    A "table-top" 2 kJ, 250 kA plasma focus, the PACO (Plasma AutoConfinado), designed by the Dense Plasma Group of IFAS is used in its optimum regime for neutron yield for obtaining collimated pulsed neutron beams (100 ns). A simple and low-cost shielding arrangement was developed in order to fully eliminate the 2.45 MeV neutrons generated in the PACO device (108 per shot at 31 kV, 1-2 mbar). Conventional neutron diagnostics: scintillator-photomultiplier (S-PMT), silver activation counters (SAC), etc., are used to determine the minimum width of the shielding walls. Emission of very hard electromagnetic pulses is also studied. Collimation using lead and copper plates is made to determine the localization of the very hard X-ray source. The maximum energy of the continuum photon distribution is estimated in 0,6 MeV using a system of filters.

  6. Application of new radiation detection techniques at the Paul Scherrer Institut, especially at the spallation neutron source

    CERN Document Server

    Lehmann, E; Williams, T; Pralong, C

    1999-01-01

    The demands on modern irradiation detection systems are diverse, encompassing spatial resolution, dynamic range, sensitivity and reproducibility. Nevertheless, there are two important new methods which can satisfy most of these demands in several applications: camera based systems and imaging plates. Imaging plates have primarily been used as gamma- and beta-sensitive detectors in biology and medicine, but are now available also as neutron sensitive systems. These methods are ideally suited for applications in neutron radiography because of their high sensitivity, linearity and digital output. Image processing, quantification of the image data and automated pattern recognition can easily be performed using modern software tools. The imaging plate system at PSI is shared between groups in reactor physics, radiation protection, biology, proton therapy and nuclear medicine. The collected experience from these different interests establishes the basis for a most effective application of this technique. The utilis...

  7. Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

    Science.gov (United States)

    Silva, Hector O.; Sotani, Hajime; Berti, Emanuele

    2016-07-01

    The lowest neutron star masses currently measured are in the range 1.0-1.1 M⊙, but these measurement have either large uncertainties or refer to isolated neutron stars. The recent claim of a precisely measured mass M/M⊙ = 1.174 ± 0.004 (Martinez et al. 2015) in a double neutron star system suggests that low-mass neutron stars may be an interesting target for gravitational-wave detectors. Furthermore, Sotani et al. recently found empirical formulas relating the mass and surface redshift of non-rotating neutron stars to the star's central density and to the parameter η ≡ (K0L2)1/3, where K0 is the incompressibility of symmetric nuclear matter and L is the slope of the symmetry energy at saturation density. Motivated by these considerations, we extend the work by Sotani et al. to slowly rotating and tidally deformed neutron stars. We compute the moment of inertia, quadrupole moment, quadrupole ellipticity, tidal and rotational Love number and apsidal constant of slowly rotating neutron stars by integrating the Hartle-Thorne equations at second order in rotation, and we fit all of these quantities as functions of η and of the central density. These fits may be used to constrain η, either via observations of binary pulsars in the electromagnetic spectrum, or via near-future observations of inspiralling compact binaries in the gravitational-wave spectrum.

  8. Neutron field measurements of the CRNA OB26 irradiator using a Bonner sphere spectrometer for radiation protection purposes.

    Science.gov (United States)

    Mazrou, H; Allab, M

    2012-08-01

    The present work deals with the Bonner sphere spectrometer (BSS) measurements performed, to support the authors' Monte-Carlo calculations, to estimate accurately the main characteristics of the neutron field of the (241)Am-Be-based OB26 irradiator acquired for radiation protection purposes by the Nuclear Research Centre of Algiers. The measurements were performed at a reference irradiation position selected at 150 cm from the geometrical centre of the neutron source. The spectrometric system in use is based on a central spherical (3)He thermal neutron proportional counter. The response matrix of the present spectrometer has been taken to be similar to the original Physikalisch-Technische Bundesanstalt (PTB) (Braunschweig, Germany) BSS's response matrix, with a five bins per decade energy group structure, as there is no significant difference in the BSS's physical characteristics. Thereafter, the authors' BSS measurements were used together with MCNP5 results to unfold the neutron spectrum by means of MAXED and GRAVEL computer codes from the U.M.G. 3.3 package, developed at PTB. Besides, sensitivity analysis has been performed to test the consistency of the unfolding procedure. It reveals that no significant discrepancy was observed in the total neutron fluence and total ambient dose values following the perturbation of some pertinent unfolding parameters except for the case where a 10 bins energy structure was assumed for the guess spectrum. In this latter case, a 5 % difference was observed in the ambient dose equivalent compared with the reference case. Finally, a comparative study performed between different counting systems together with MCNP5 and predictive formulas results shows that they were globally satisfactory, highlighting thereby the relevance of the unfolding procedure and the reliability of the obtained results.

  9. Cellular response to ionizing radiations: a study of the roles of physics and biology. [Neutrons (14 MeV); X radiation

    Energy Technology Data Exchange (ETDEWEB)

    DeWyngaert, J.K.

    1982-01-01

    A study of the complementary roles of physics and biology in determining the response of cellular systems to ionizing radiations has been conducted. Upon exposure to radiation, a cell responds in a binary (yes/no) manner in terms of its proliferative ability (survival). The relationship between the survival probability and absorbed dose may then be examined in terms of relevant physical and biological parameters. The approach to these studies was to vary the physics and biology independently and observe separately their influences upon the measured effect. Unique to these studies was the use of heterogeneous tumor systems. These are solid tumors found to consist of genetically related but identifiably distinct populations of cells. The two heterogeneous systems studied, a murine system consisting of four subpopulations and a human tumor system with two subpopulations, were exposed to graded doses of 14 MeV neutrons or x-rays and their effectiveness in inducing cell lethality compared. A further examination of the radiation effect involved a study at the chemical level, measuring the ability of oxygen to potentiate the damage produced by photon irradiation. To summarize, the physics, biology and the environment have all been varied, and the systematics of the responses studied. The data were analyzed within the formalisms of the dual theory of radiation action, the repair-misrepair model, and the repair saturation model of cell killing. The change in survival curve shape and the increased effectiveness in cell killing for higher Linear Energy Transfer (LET) radiations (neutrons vs. x-rays) are discussed in relation to explanations in terms of either physical or biochemical processes.

  10. Intercomparison of radiation protection devices in a high-energy stray neutron field. Part II: Bonner sphere spectrometry

    CERN Document Server

    Wiegel, B; Bedogni, R; Caresana, M; Esposito, A; Fehrenbacher, G; Ferrarini, M; Hohmann, E; Hranitzky, C; Kasper, A; Khurana, S; Mares, V; Reginatto, M; Rollet, S; Rühm, W; Schardt, D; Silari, M; Simmer, G; Weitzenegger, E

    2009-01-01

    The European Commission has funded within its 6th Framework Programme a three-year project (2005–2007) called CONRAD, COordinated Network for RAdiation Dosimetry. A major task of the CONRAD Work Package “complex mixed radiation fields at workplaces” was to organise a benchmark exercise in a workplace field at a high-energy particle accelerator where neutrons are the dominant radiation component. The CONRAD benchmark exercise took place at the Gesellschaft für Schwerionenforschung mbH (GSI) in Darmstadt, Germany in July 2006. In this paper, the results of the spectrometry using four extended -range Bonner sphere spectrometers of four different institutes are reported. Outside Cave A the neutron spectra were measured with three spectrometers at six selected positions and ambient dose equivalent values were derived for use in the intercomparison with other area monitors and dosemeters. At a common position all three spectrometers were used to allow a direct comparison of their results which acts as an int...

  11. Gravitational radiation and gamma-ray bursts from accreting neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Mosquera Cuesta, H.J.; Araujo, J.C.N. de; Aguiar, O.D. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Astrofisica]. E-mail: herman@das.inpe.br; jcarlos@das.inpe.br; odylio@das.inpe.br; Horvath, J.E. [Sao Paulo Univ., SP (Brazil). Inst. Astronomico e Geofisico]. E-mail: foton@orion.iagusp.usp.br

    2000-07-01

    It is well known that hydrodynamic instabilities can be induced in rapidly rotating low magnetic field neutron stars, which accrete mass from a companion in both high and low mass X-ray binaries. (author)

  12. Experimental mutagenesis of marker loci in maize. [Gamma radiation, fission neutrons, EMS, NaN/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Conger, B.V.

    1976-01-01

    Studies on induction of germinal mutations at five loci were carried out using /sup 60/Co radiation, fission neutrons, EMS, or NaN/sub 3/. The resulting plants were crossed to nontreated plants homozygous recessive for the same loci. A higher frequency of mutants was recovered when treated plants were used as male rather than female parents. Other experiments were conducted on induction of somatic mutations at the yg/sub 2/ locus and determination of cell populations in embryonic shoots and cell cycle in the shoot apex. Results are tabulated and the significance of the results are discussed. (HLW)

  13. Variability for components of yield induced in soybeans by seed treatment with gamma radiation, fission neutrons, and ethylmethane sulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Conger, B.V.; Skinner, L.W.; Skold, L.N.

    1976-01-01

    The variability for individual components of yield in soybean (Glycine max (L.) Merr.) induced by seed treatment with fission neutrons, gamma radiation, and ethylmethane sulfonate was studied. Nine M/sub 3/ populations, including three doses of each mutagen, were compared with a control for pods/plant, wt/100 seeds, and total seed wt/plant. The means for individual yield components were not significantly altered by the mutagenic treatments. A comparison of frequency distributions of populations from mutagen-treated seed vs. the control revealed differences for certain treatments. The most effective mutagen for increasing variability of the yield components was ethylmethane sulfonate.

  14. Quinolone and glycopeptide therapy for infection in mouse following exposure to mixed-field neutron-[gamma]-photon radiation

    Energy Technology Data Exchange (ETDEWEB)

    Brook, I. (Naval Medical Research Inst., Bethesda, MD (United States) Armed Forces Radiobiology Research Inst., Bethesda, MD (United States)); Tom, S.P.; Ledney, G.D. (Armed Forces Radiobiology Research Inst., Bethesda, MD (United States))

    1993-12-01

    The effects of increased doses of mixed-field neutron-[gamma]-photon irradiation on bacterial translocation and subsequent sepsis, and the influence of antimicrobial therapy on these events, were studied in the C3H/HeN mouse. The results demonstrate a relationship between the doses of mixed-field radiation and the rates of infection due to Enterobacteriaceae. While L-ofloxacin therapy reduces the infection rate, prolongs survival and prevents mortality, the addition of a glycopeptide can enhance systemic infection by resistant bacteria in the irradiated host. (author).

  15. Low-mass neutron stars: universal relations, the nuclear symmetry energy and gravitational radiation

    CERN Document Server

    Silva, Hector O; Berti, Emanuele

    2016-01-01

    The lowest neutron star masses currently measured are in the range $1.0-1.1~M_\\odot$, but these measurement have either large uncertainties or refer to isolated neutron stars. The recent claim of a precisely measured mass $M/M_{\\odot} = 1.174 \\pm 0.004$ by Martinez et al [Astrophys.J. 812, 143 (2015)] in a double neutron star system suggests that low-mass neutron stars may be an interesting target for gravitational-wave detectors. Furthermore, Sotani et al [PTEP 2014, 051E01 (2014)] recently found empirical formulas relating the mass and surface redshift of nonrotating neutron stars to the star's central density and to the parameter $\\eta\\equiv (K_0 L^2)^{1/3}$, where $K_0$ is the incompressibility of symmetric nuclear matter and $L$ is the slope of the symmetry energy at saturation density. Motivated by these considerations, we extend the work by Sotani et al to slowly rotating and tidally deformed neutron stars. We compute the moment of inertia, quadrupole moment, quadrupole ellipticity, tidal and rotationa...

  16. Radiation damage and waste management options for the sombrero final focus system and neutron dumps

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, S.; Latkowski, J.F.; Meier, W.R. [Lawrence Livermore National Lab., CA (United States); Reyes, S. [Escuela Tecnica Superior de Ingenieros Industriales, Universidad Nacional de Educacion a Distancia and Instituto de Fusion Nuclear, Dept. Ingenieria Energetica, Bilbao (Spain)

    2000-07-01

    Previous studies of the safety and environmental aspects of the SOMBRERO inertial fusion energy (IFE) power plant design did not completely address the issues associated with the final focus system. While past work calculated neutron fluences for a grazing incidence metal mirror (GIMM) and a final focus mirror, scattering off of the final optical component was not included, and thus, fluences in the final focus mirror were significantly underestimated. In addition, past work did not consider neutron-induced gamma-rays. Finally, power plant lifetime waste volumes may have been underestimated as neutron activation of the neutron dumps and building structure were not addressed. In the present work, a modified version of the SOMBRERO target building is presented where a significantly larger open solid-angle fraction (5%) is used to enhance beam smoothing of a diode-pumped solid-state laser (DPSSL). The GIMMs are replaced with transmissive fused silica wedges and have been included in three-dimensional neutron and photon transport calculations. This work shows that a power plant with a large open solid-angle fraction, needed for beam smoothing with a DPSSL, is acceptable from tritium breeding, and neutron activation points-of-view. (authors)

  17. Principles of medical rehabilitation of survivors of acute radiation sickness induced by gamma and beta and gumma and neutron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nedejina, N.M.; Galstian, I.A.; Savitsky, A.A.; Sachkov, A.V.; Rtisheva, J.N.; Uvatcheva, I.V.; Filin, S.V. [State Research Center of Russia, Moscow (Russian Federation). Inst. of Biophysics

    2000-05-01

    The purpose of this study is to reveal the principles of medical rehabilitation different degree acute radiation syndrome (ARS) survivors, who exposed {gamma}{beta}- and {gamma}{eta}-irradiation in different radiation accidents. The main reasons of working disability in the late consequences of ARS period are consequences of local radiation injures (LRI) and joining somatic diseases. Its revealing and treatment considerably improves quality of life of the patients. The heaviest consequence of LRI of a skin at {gamma}{beta}- radiation exposure is the development of late radiation ulcers and radiation fibrosis, which require repeated plastic surgery. LRI at {gamma}{eta}-radiation exposure differ by the greater depth of destruction of a underlying tissues and similar defects require the early amputations. Last 10 years microsurgery methods of plastic surgery allow to save more large segments of extremities and to decrease expression of the late consequences (radiation fibrosis and late radiation ulcers) LRI severe and extremely severe degrees. Medical rehabilitation of radiation cataract (development at doses more than 2.0 Gy) includes its extraction and artificial lens implantation, if acuity of vision is considerably decreased. Changes of peripheral blood, observed at the period of the long consequences, as a rule, different, moderate, transient and not requiring treatment. Only one ARS survivor dead from chronic myeloid leukemia. Thyroid nodes, not requiring operative intervention, are found out in Chernobyl survivors. Within the time course the concurrent somatic disease become the major importance for patients disability growth, which concurrent diseases seem to be unrelated to radiation dose and their structure does not differ from that found in general public of Russia. The rehabilitation of the persons who have transferred ARS as a result of radiating failure, should be directed on restoration of functions critical for ionizing of radiation of bodies and

  18. [Effect of IL-2 on the growth and apoptosis of intestinal epithelial cells radiated by neutron and mechanisms of IL-2 on the injured IEC-6].

    Science.gov (United States)

    Fu, Kai-fei; Peng, Rui-yun; Gao, Ya-bing; Wang, De-wen; Luo, Qing-liang; Dong, Bo; Ma, Jun-jie

    2007-08-01

    To observe the effect of neutron radiation on intestinal epithelial cells 6 (IEC-6), to study the effect of IL-2 on the proliferation and recovery of neutron-injured IEC-6, and to investigate the regulatory mechanisms of IL-2 on the injured IEC-6. 4Gy-neutron-injured IEC-6 were treated by IL-2, with or without the blocking agent JAK(1) (A77-1726). The change of proliferative activity and death manner of the treated IEC-6 were detected by MTT colorimetry and flow cytometry at 10, 15, 30 minutes and 1, 3, 6, 12, 24, 48, 72 hours respectively. The expression of IL-2Rbeta and the activation of JAK(1) of neutron-injured IEC-6 treated by IL-2 were detected by immunocytochemical stainning and Western blot. After IEC-6 were radiated by 4 Gy neutron for 24 hours, the proliferative activity of IEC-6 decreased markedly but increased strikingly after IL-2 treatment (PIEC-6 in IL-2-treated group decreased (PIEC-6 were treated by IL-2, JAK(1) was activated at 10 and 15 minutes, and the expression of IL-2Rbeta increased apparently at 24 hours. When treated by JAK(1) and IL-2, the proliferative activity of neutron-injured IEC-6 was much lower than that in IL-2-treated group. IL-2 can accelerate the proliferation of neutron-radiated IEC-6 and protect them from neutron injury. IL-2Rbeta and JAK(1) participate in the regulation of neutron-injured IEC-6 by IL-2.

  19. A fine study on gamma radiation in interaction of 14.9 MeV neutron with natural copper

    CERN Document Server

    Deng Fu Guo; Wang Xin Fu; Fan Guo Ying; Hua Ming; Lu Ting

    2001-01-01

    The discrete gamma-ray spectra at 55 degree and 90 degree in the reactions of 14.9 MeV neutrons in natural copper are investigated by using total gamma radiation measurement technique (TGRM) in fast neutron nuclear reaction. There are 107 gamma-rays distinguished by means of a high-resolution gamma-ray analysis code. The production cross sections, the reaction modes and the transition levels of these gamma-rays at the two angles are determined. It is found that the gamma lines come mainly from the reactions of sup 6 sup 3 Cu(n, 2n gamma) sup 6 sup 2 Cu, sup 6 sup 5 Cu(n, 2n gamma) sup 6 sup 4 Cu, sup 6 sup 3 Cu(n, n'gamma) sup 6 sup 3 Cu, sup 6 sup 5 Cu(n, n'gamma) sup 6 sup 5 Cu, etc. Analysis of the activated background spectrum shows that natural copper is an ideal shielding material in fast neutron nuclear reactions

  20. Bubble-detector measurements of neutron radiation in the international space station: ISS-34 to ISS-37.

    Science.gov (United States)

    Smith, M B; Khulapko, S; Andrews, H R; Arkhangelsky, V; Ing, H; Koslowksy, M R; Lewis, B J; Machrafi, R; Nikolaev, I; Shurshakov, V

    2016-02-01

    Bubble detectors have been used to characterise the neutron dose and energy spectrum in several modules of the International Space Station (ISS) as part of an ongoing radiation survey. A series of experiments was performed during the ISS-34, ISS-35, ISS-36 and ISS-37 missions between December 2012 and October 2013. The Radi-N2 experiment, a repeat of the 2009 Radi-N investigation, included measurements in four modules of the US orbital segment: Columbus, the Japanese experiment module, the US laboratory and Node 2. The Radi-N2 dose and spectral measurements are not significantly different from the Radi-N results collected in the same ISS locations, despite the large difference in solar activity between 2009 and 2013. Parallel experiments using a second set of detectors in the Russian segment of the ISS included the first characterisation of the neutron spectrum inside the tissue-equivalent Matroshka-R phantom. These data suggest that the dose inside the phantom is ∼70% of the dose at its surface, while the spectrum inside the phantom contains a larger fraction of high-energy neutrons than the spectrum outside the phantom. The phantom results are supported by Monte Carlo simulations that provide good agreement with the empirical data. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Dynamical mass ejection from the merger of asymmetric binary neutron stars: Radiation-hydrodynamics study in general relativity

    CERN Document Server

    Sekiguchi, Yuichiro; Kyutoku, Koutarou; Shibata, Masaru; Taniguchi, Keisuke

    2016-01-01

    We perform neutrino radiation-hydrodynamics simulations for the merger of asymmetric binary neutron stars in numerical relativity. Neutron stars are modeled by soft and moderately stiff finite-temperature equations of state (EOS). We find that the properties of the dynamical ejecta such as the total mass, neutron richness profile, and specific entropy profile depend on the mass ratio of the binary systems for a given EOS in a unique manner. For the soft EOS (SFHo), the total ejecta mass depends weakly on the mass ratio, but the average of electron number per baryon ($Y_e$) and specific entropy ($s$) of the ejecta decreases significantly with the increase of the degree of mass asymmetry. For the stiff EOS (DD2), with the increase of the mass asymmetry degree, the total ejecta mass significantly increases while the average of $Y_e$ and $s$ moderately decreases. We find again that only for the soft EOS (SFHo), the total ejecta mass exceeds $0.01M_\\odot$ irrespective of the mass ratio chosen in this paper. The ej...

  2. Detection of fast neutrons from D-T nuclear reaction using a 4H-SiC radiation detector

    Science.gov (United States)

    Zatko, Bohumir; Sagatova, Andrea; Sedlackova, Katarina; Necas, Vladimir; Dubecky, Frantisek; Solar, Michael; Granja, Carlos

    2016-09-01

    The particle detector based on a high purity epitaxial layer of 4H-SiC exhibits promising properties in detection of various types of ionizing radiation. Due to the wide band gap of 4H-SiC semiconductor material, the detector can reliably operate at room and also elevated temperatures. In this work we focused on detection of fast neutrons generated the by D-T (deuterium-tritium) nuclear reaction. The epitaxial layer with a thickness of 105 μm was used as a detection part. A circular Schottky contact of a Au/Ni double layer was evaporated on both sides of the detector material. The detector structure was characterized by current-voltage and capacitance-voltage measurements, at first. The results show very low current density (SiC detector is caused by the elastic and inelastic scattering on the silicon or carbide component of the detector material. Another possibility that increases the detection efficiency is the use of a conversion layer. In our measurements, we glued a HDPE (high density polyethylene) conversion layer on the detector Schottky contact to transform fast neutrons to protons. Hydrogen atoms contained in the conversion layer have a high probability of interaction with neutrons through elastic scattering. Secondary generated protons flying to the detector can be easily detected. The detection properties of detectors with and without the HDPE conversion layer were compared.

  3. Neutron Radiography

    Science.gov (United States)

    Heller, A. K.; Brenizer, J. S.

    Neutron radiography and its related two-dimensional (2D) neutron imaging techniques have been established as invaluable nondestructive inspection methods and quantitative measurement tools. They have been used in a wide variety of applications ranging from inspection of aircraft engine turbine blades to study of two-phase fluid flow in operating proton exchange membrane fuel cells. Neutron radiography is similar to X-ray radiography in that the method produces a 2D attenuation map of neutron radiation that has penetrated the object being examined. However, the images produced differ and are often complementary due to the differences between X-ray and neutron interaction mechanisms. The uses and types of 2D neutron imaging have expanded over the past 15 years as a result of advances in imaging technology and improvements in neutron generators/sources and computers. Still, high-intensity sources such as those from reactors and spallation neutron sources, together with conventional film radiography, remain the mainstay of high-resolution, large field-of-view neutron imaging. This chapter presents a summary of the history, methods, and related variations of neutron radiography techniques.

  4. Monte Carlo simulation of mixed neutron-gamma radiation fields and dosimetry devices

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoqing

    2011-12-22

    Monte Carlo methods based on random sampling are widely used in different fields for the capability of solving problems with a large number of coupled degrees of freedom. In this work, Monte Carlos methods are successfully applied for the simulation of the mixed neutron-gamma field in an interim storage facility and neutron dosimeters of different types. Details are discussed in two parts: In the first part, the method of simulating an interim storage facility loaded with CASTORs is presented. The size of a CASTOR is rather large (several meters) and the CASTOR wall is very thick (tens of centimeters). Obtaining the results of dose rates outside a CASTOR with reasonable errors costs usually hours or even days. For the simulation of a large amount of CASTORs in an interim storage facility, it needs weeks or even months to finish a calculation. Variance reduction techniques were used to reduce the calculation time and to achieve reasonable relative errors. Source clones were applied to avoid unnecessary repeated calculations. In addition, the simulations were performed on a cluster system. With the calculation techniques discussed above, the efficiencies of calculations can be improved evidently. In the second part, the methods of simulating the response of neutron dosimeters are presented. An Alnor albedo dosimeter was modelled in MCNP, and it has been simulated in the facility to calculate the calibration factor to get the evaluated response to a Cf-252 source. The angular response of Makrofol detectors to fast neutrons has also been investigated. As a kind of SSNTD, Makrofol can detect fast neutrons by recording the neutron induced heavy charged recoils. To obtain the information of charged recoils, general-purpose Monte Carlo codes were used for transporting incident neutrons. The response of Makrofol to fast neutrons is dependent on several factors. Based on the parameters which affect the track revealing, the formation of visible tracks was determined. For

  5. Enhancement of neutron radiation dose by the addition of sulphur-33 atoms

    Energy Technology Data Exchange (ETDEWEB)

    Porras, I [Departamento de Fisica Atomica, Molecular y Nuclear (formerly Fisica Moderna), Facultad de Ciencias, Universidad de Granada, E-18071 Granada (Spain)], E-mail: porras@ugr.es

    2008-04-07

    The use of neutrons in radiotherapy allows the possibility of producing nuclear reactions in a specific target inserted in the medium. {sup 10}B is being used to induce reactions (n, {alpha}), a technique called boron neutron capture therapy. I have studied the possibility of inducing a similar reaction using the nucleus of {sup 33}S, for which the reaction cross section presents resonances for keV neutrons, the highest peak occurring at 13.5 keV. Here shown, by means of Monte Carlo simulation of point-like sources of neutrons in this energy range, is an enhancement effect on the absorbed dose in water by the addition of {sup 33}S atoms. In addition to this, as the range of the alpha particle is of the order of a mammalian cell size, the energy deposition via this reaction results mainly inside the cells adjacent to the interaction site. The main conclusion of the present work is that the insertion of these sulphur atoms in tumoral cells would enhance the effect of neutron irradiation in the keV range. (letter to the editor)

  6. Effect of particle size and percentages of Boron carbide on the thermal neutron radiation shielding properties of HDPE/B4C composite: Experimental and simulation studies

    Science.gov (United States)

    Soltani, Zahra; Beigzadeh, Amirmohammad; Ziaie, Farhood; Asadi, Eskandar

    2016-10-01

    In this paper the effects of particle size and weight percentage of the reinforcement phase on the absorption ability of thermal neutron by HDPE/B4C composites were investigated by means of Monte-Carlo simulation method using MCNP code and experimental studies. The composite samples were prepared using the HDPE filled with different weight percentages of Boron carbide powder in the form of micro and nano particles. Micro and nano composite were prepared under the similar mixing and moulding processes. The samples were subjected to thermal neutron radiation. Neutron shielding efficiency in terms of the neutron transmission fractions of the composite samples were investigated and compared with simulation results. According to the simulation results, the particle size of the radiation shielding material has an important role on the shielding efficiency. By decreasing the particle size of shielding material in each weight percentages of the reinforcement phase, better radiation shielding properties were obtained. It seems that, decreasing the particle size and homogeneous distribution of nano forms of B4C particles, cause to increase the collision probability between the incident thermal neutron and the shielding material which consequently improve the radiation shielding properties. So, this result, propose the feasibility of nano composite as shielding material to have a high performance shielding characteristic, low weight and low thick shielding along with economical benefit.

  7. Solution-grown crystals for neutron radiation detectors, and methods of solution growth

    Science.gov (United States)

    Zaitseva, Natalia; Carman, M Leslie; Payne, Steve

    2014-10-28

    An organic crystal according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source. A system according to one embodiment includes an organic crystal comprising diphenylacetylene and stilbene or a stilbene derivative, the crystal having physical characteristics of formation from solution, the organic crystal exhibiting a signal response signature for neutrons from a radioactive source; and a photodetector for detecting the signal response of the organic crystal. Methods of making such crystals are also provided.

  8. Neutron and gamma radiation tests of the Analog Devices TMP37 temperature sensors

    CERN Document Server

    Mockett, P M; Twomey, M S

    2004-01-01

    The Analog Devices TMP37 temperature sensor is used to monitor the temperature gradients in the US ATLAS End Cap Muon Chambers. It was chosen because of its stability, linearity, high output signal, and especially the low self-heating. We have irradiated samples of these sensors with neutrons and gamma rays. The results of these measurements are presented.

  9. Neutron-Activation Analysis of Biological Material with High Radiation Levels

    Energy Technology Data Exchange (ETDEWEB)

    Samsahl, K.

    1966-09-15

    A method has been developed for the chemical separation and subsequent gamma-spectrometric analysis of the alkali metals, the alkaline earths, the rare earths, chromium, hafnium, lanthanum, manganese, phosphorus, scandium and silver in neutron-activated biological material. The separation steps, being fully automatic, are based on a combination of ion-exchange and partition chromatography and require 40 min.

  10. Transient and chronic neurological complications of fast neutron radiation for adenocarcinoma of the prostate

    Energy Technology Data Exchange (ETDEWEB)

    Russell, K.J.; Laramore, G.E.; Wiens, L.W.; Griffeth, J.T.; Koh, W.J.; Griffin, B.R.; Austin-Seymour, M.M.; Griffin, T.W. (Washington Univ., Seattle, WA (USA). Lab. of Radiation Ecology); Krieger, J.N. (Washington University, Seattle (USA). Department of Urology); Davis, L.W. (Albert Einstein Coll. of Medicine, Bronx, NY (USA))

    1990-07-01

    The records of 132 patients participating in clinical trials using fast neutron (n = 94), mixed neutron and photon (n = 16), or conventional photon (n = 22) irradiation for primary management of prostatic cancer were retrospectively reviewed to assess treatment-related neurological complications. With a median follow-up of 14 months (range 1 to 101 months), 31/132 patients (26 neutron, 3 mixed beam, 2 photon) have experienced either sciatica beginning during or shortly after treatment, or diminished bladder or bowel continence that developed at a median time of 6.5 months following treatment. Sciatica responded to oral steroids and was usually self-limited, whereas sphincter dysfunction appears to be permanent. Pre-treatment risk factors for complications included a history of hypertension, diabetes, cigarette smoking or peripheral vascular disease, with 81% of affected patients having one or more risk factors compared witn 55% of unaffected patients (p = 0.01). Seven patients have moderate (5) or severe (2) residual problems, all in the cohorts receiving neutrons (6/7) or mixed beam therapy (1/7). (author). 31 refs.; 5 tabs.

  11. Monte-Carlo investigation of radiation beam quality of the CRNA neutron irradiator for calibration purposes

    Energy Technology Data Exchange (ETDEWEB)

    Mazrou, Hakim, E-mail: mazrou_h@crna.d [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz, Fanon, B.P. 399, Alger-RP 16000 (Algeria); Sidahmed, Tassadit [Centre de Recherche Nucleaire d' Alger (CRNA), 02 Boulevard Frantz, Fanon, B.P. 399, Alger-RP 16000 (Algeria); Allab, Malika [Faculte de Physique, Universite des Sciences et de la Technologie de Houari-Boumediene (USTHB), 16111, Alger (Algeria)

    2010-10-15

    An irradiation system has been acquired by the Nuclear Research Center of Algiers (CRNA) to provide neutron references for metrology and dosimetry purposes. It consists of an {sup 241}Am-Be radionuclide source of 185 GBq (5 Ci) activity inside a cylindrical steel-enveloped polyethylene container with radially positioned beam channel. Because of its composition, filled with hydrogenous material, which is not recommended by ISO standards, we expect large changes in the physical quantities of primary importance of the source compared to a free-field situation. Thus, the main goal of the present work is to fully characterize neutron field of such special delivered set-up. This was conducted by both extensive Monte-Carlo calculations and experimental measurements obtained by using BF{sub 3} and {sup 3}He based neutron area dosimeters. Effects of each component present in the bunker facility of the Algerian Secondary Standard Dosimetry Laboratory (SSDL) on the energy neutron spectrum have been investigated by simulating four irradiation configurations and comparison to the ISO spectrum has been performed. The ambient dose equivalent rate was determined based upon a correct estimate of the mean fluence to ambient dose equivalent conversion factors at different irradiations positions by means of a 3-D transport code MCNP5. Finally, according to practical requirements established for calibration purposes an optimal irradiation position has been suggested to the SSDL staff to perform, in appropriate manner, their routine calibrations.

  12. Radiation detector based on 4H-SiC used for thermal neutron detection

    Science.gov (United States)

    Zaťko, B.; Šagátová, A.; Sedlačková, K.; Boháček, P.; Sekáčová, M.; Kohout, Z.; Granja, C.; Nečas, V.

    2016-11-01

    In this work we have focused on detection of thermal neutrons generated by 239Pu-Be isotopic neutron source. A high quality liquid phase epitaxial layer of 4H-SiC was used as a detection region. The thickness of the layer was 70 μ m and the diameter of circular Au/Ni Schottky contact was 4.5 mm. Around the Schottky contact two guard rings were created. The detector structure was first examined as a detector of protons and alpha particles for energy calibration. Monoenergetic protons of energies from 300 keV up to 1.9 MeV were used for detector energy calibration and a good linearity was observed. The energy resolution of 35 keV was obtained for 1.9 MeV protons. The 6LiF conversion layer was applied on the detector Schottky contact. In the experiment we used different thicknesses of conversion layers from 5 μ m up to 35 μ m. Measured detected spectra show two parts corresponding to alpha particles detection in lower energy channels and 3H in higher energy channels. We have also performed simulations of thermal neutron detection using MCNPX (Monte Carlo N-particle eXtended) code. The detection efficiency and the detector response to thermal neutrons was calculated with respect to the 6LiF layer thickness. The detection efficiency calculation is found to be in good agreement with the experiment.

  13. Neutron and y-Ray Radiation Killing of Bacillus Species Spores: Dosimetry, Quantitation, and Validation Techniques

    Science.gov (United States)

    1996-04-01

    Radiobiology Research Institute under work unit 00129. References 1. American Association of Physicists in Medicine (1983) AAPM Task Group 21. A protocol...dose. Journal of the Parenteral Drug Association 33:144- 155 19. Zeman GH, Ferlic KP (1984) Paired ion chamber constants for fission 7-neutron fields

  14. Numerical Solution of the Radiative Transfer Equation: X-Ray Spectral Formation from Cylindrical Accretion onto a Magnetized Neutron Star

    Science.gov (United States)

    Fairnelli, R.; Ceccobello, C.; Romano, P.; Titarchuk, L.

    2011-01-01

    Predicting the emerging X-ray spectra in several astrophysical objects is of great importance, in particular when the observational data are compared with theoretical models. This requires developing numerical routines for the solution of the radiative transfer equation according to the expected physical conditions of the systems under study. Aims. We have developed an algorithm solving the radiative transfer equation in the Fokker-Planck approximation when both thermal and bulk Comptonization take place. The algorithm is essentially a relaxation method, where stable solutions are obtained when the system has reached its steady-state equilibrium. Methods. We obtained the solution of the radiative transfer equation in the two-dimensional domain defined by the photon energy E and optical depth of the system pi using finite-differences for the partial derivatives, and imposing specific boundary conditions for the solutions. We treated the case of cylindrical accretion onto a magnetized neutron star. Results. We considered a blackbody seed spectrum of photons with exponential distribution across the accretion column and for an accretion where the velocity reaches its maximum at the stellar surface and at the top of the accretion column, respectively. In both cases higher values of the electron temperature and of the optical depth pi produce flatter and harder spectra. Other parameters contributing to the spectral formation are the steepness of the vertical velocity profile, the albedo at the star surface, and the radius of the accretion column. The latter parameter modifies the emerging spectra in a specular way for the two assumed accretion profiles. Conclusions. The algorithm has been implemented in the XPEC package for X-ray fitting and is specifically dedicated to the physical framework of accretion at the polar cap of a neutron star with a high magnetic field (approx > 10(exp 12) G). This latter case is expected to be of typical accreting systems such as X

  15. Accumulation and annealing of radiation defects under low-temperature electron and neutron irradiation of ODS steel and Fe-Cr alloys

    Science.gov (United States)

    Arbuzov, V. L.; Goshchitskii, B. N.; Sagaradze, V. V.; Danilov, S. E.; Kar'kin, A. E.

    2010-10-01

    The processes of accumulation and annealing of radiation defects at low-temperature (77 K) electron and neutron irradiation and their effect on the physicomechanical properties of Fe-Cr alloys and oxide dispersion strengthened (ODS) steel have been studied. It has been shown that the behavior of radiation defects in ODS steel and Fe-Cr alloys is qualitatively similar. Above 250 K, radiation-induced processes of the solid solution decomposition become conspicuous. These processes are much less pronounced in ODS steel because of specific features of its microstructure. Processes related to the overlapping of displacement cascades under neutron irradiation have been considered. It has been shown that, in this case, it is the increase in the size of vacancy clusters, rather than the growth of their concentration, that is prevailing. Possible mechanisms of the radiation hardening of the ODS steel and the Fe-13Cr alloy upon irradiation and subsequent annealing have been discussed.

  16. Radiation portal monitor with {sup 10}B+ZnS(Ag) neutron detector performance for the detection of special nuclear materials

    Energy Technology Data Exchange (ETDEWEB)

    Guzman G, K. A.; Gallego, E.; Lorente, A.; Ibanez F, S. [Universidad Politecnica de Madrid, Departamento de Ingenieria Energetica, ETSI Industriales, C. Jose Gutierrez Abascal 2, 28006 Madrid (Spain); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico); Gonzalez, J. A. [Universidad Politecnica de Madrid, Laboratorio de Ingenieria Nuclear, ETSI Caminos, Canales y Puertos, C. Prof. Aranguren 3, 28040 Madrid (Spain); Mendez, R., E-mail: ingkarenguzman@gmail.com [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Laboratorio de Patrones Neutronicos, Av. Complutense 40, 28040 Madrid (Spain)

    2016-10-15

    In homeland security, neutron detection is used to prevent the smuggling of special nuclear materials. Thermal neutrons are normally detected with {sup 3}He proportional counters, in the radiation portal monitors, Rpms, however due to the {sup 3}He shortage new procedures are being studied. In this work Monte Carlo methods, using the MCNP6 code, have been used to study the neutron detection features of a {sup 10}B+ZnS(Ag) under real conditions inside of a Rpm. The performance for neutron detection was carried out for {sup 252}Cf, {sup 238}U and {sup 239}Pu under different conditions. In order to mimic an actual situation occurring at border areas, a sample of SNM sited inside a vehicle was simulated and the Rpm with {sup 10}B+ZnS(Ag) response was calculated. At 200 cm the {sup 10}B+ZnS(Ag) on Rpm response is close to 2.5 cps-ng {sup 252}Cf, when the {sup 252}Cf neutron source is shielded with 0.5 cm-thick lead and 2.5 cm-thick polyethylene fulfilling the ANSI recommendations. Three different geometries of neutron detectors of {sup 10}B+ZnS(Ag) in a neutron detection system in Rpm were modeled. Therefore, the {sup 10}B+ZnS(Ag) detectors are an innovative and viable replacement for the {sup 3}He detectors in the Rpm. (Author)

  17. Radiation damage induced in Al{sub 2}O{sub 3} single crystal sequentially irradiated with reactor neutrons and 90 MeV Xe ions

    Energy Technology Data Exchange (ETDEWEB)

    Zirour, H. [Faculty of Physics, USTHB, BP. 32, El-Alia, Bab-Ezzouar, Algiers (Algeria); Izerrouken, M., E-mail: izerrouken@yahoo.com [Centre de Recherche Nucléaire de Draria, BP. 43, Sebbala, Draria, Algiers (Algeria); Sari, A. [Centre de Recherche Nucléaire de Berine, BP. 108, Ain-Oussara, Djelfa (Algeria)

    2016-06-15

    The present investigation reports the effect of 90 MeV Xe ion irradiation on neutron irradiated Al{sub 2}O{sub 3} single crystals. Three irradiation experiments were performed, with neutrons only, 90 MeV Xe ions only and with neutrons followed by 90 MeV Xe ions. Neutron and 90 MeV Xe ion irradiations were performed at NUR research reactor, Algiers, Algeria and at GANIL accelerator, Caen, France respectively. After irradiation, the radiation damage was investigated by Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), optical absorption measurements, and X-ray diffraction (XRD) techniques. Raman technique revealed that the concentration of the defects formed in Al{sub 2}O{sub 3} samples subsequently irradiated with neutrons and 90 MeV Xe ions is lower than that formed in Al{sub 2}O{sub 3} samples which were irradiated only with neutrons. This reveals the occurrence of ionization-induced recovery of the neutron damage. Furthermore, as revealed by XRD analysis, a new peak is appeared at about 2θ = 38.03° after irradiation at high fluence (>3 × 10{sup 13} Xe/cm{sup 2}). It can be assigned to the formation of new lattice plane.

  18. Studies on application of radiation and radioisotopes -Studies on application of neutron activation analysis-

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yong Sam; Jung, Yung Joo; Jung, Eui Sik; Lee, Sang Mee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Kim, Nak Bae [Korea Institute of Geology, Mining and Materials, Taejon (Korea, Republic of)

    1995-07-01

    To apply Neutron activation analysis to routine analysis of environmental samples utilizing the research reactor (TRIGA MK-III), improving effects of analytical sensitivity have been investigated using both of thermal and epithermal neutron irradiating technique. Identification and development of analytical procedure was carried out using three kinds of standard reference materials (urban particulate matter, coal fly ash, soil). In addition, the confidence of this method was established by participation in collaborative research for the training and apply of international credit of analytical procedure. Practical studies on air dust samples have also been carried out regionally and seasonally. For the investigation on emission source of special element, enrichment factor was calculated in urban and rural area. Besides, a suitable process of biological sample (pine needle) analyses has been established by carrying out identification of uncertainty using standard reference material. The concentration of elements in practical samples were also determined regionally and seasonally. 14 figs, 26 tabs, 67 refs. (Author).

  19. Development of Advanced Multi-Modality Radiation Treatment Planning Software for Neutron Radiotherapy and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Nigg, D; Wessol, D; Wemple, C; Harkin, G; Hartmann-Siantar, C

    2002-08-20

    The Idaho National Engineering and Environmental Laboratory (INEEL) has long been active in development of advanced Monte-Carlo based computational dosimetry and treatment planning methods and software for advanced radiotherapy, with a particular focus on Neutron Capture Therapy (NCT) and, to a somewhat lesser extent, Fast-Neutron Therapy. The most recent INEEL software system of this type is known as SERA, Simulation Environment for Radiotherapy Applications. As a logical next step in the development of modern radiotherapy planning tools to support the most advanced research, INEEL and Lawrence Livermore National Laboratory (LLNL), the developers of the PEREGRTNE computational engine for radiotherapy treatment planning applications, have recently launched a new project to collaborate in the development of a ''next-generation'' multi-modality treatment planning software system that will be useful for all modern forms of radiotherapy.

  20. The merging of white dwarf and neutron star systems: gravitational radiation

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Berro, Enrique [Departament de Fisica Aplicada, Escola Politecnica Superior de Castelldefels, Universitat Politecnica de Catalunya, Avda. del Canal OlImpic s/n, 08860 Castelldefels (Spain); Pedemonte, Alba G [Departament de Fisica Aplicada, Escola Politecnica Superior de Castelldefels, Universitat Politecnica de Catalunya, Avda. del Canal OlImpic s/n, 08860 Castelldefels (Spain); GarcIa-Senz, Domingo [Departament de Fisica i Enginyeria Nuclear, Facultat de Informatica de Barcelona, Universitat Politecnica de Catalunya, c/ Jordi Girona Salgado, s/n, 08034, Barcelona (Spain); Loren-Aguilar, Pablo [Institut de Ciencies de l' Espai, CSIC, Facultat de Ciencies, Campus UAB, 08193 Bellaterra (Spain); Isern, Jordi [Institut de Ciencies de l' Espai, CSIC, Facultat de Ciencies, Campus UAB, 08193 Bellaterra (Spain); Lobo, Jose A [Institut de Ciencies de l' Espai, CSIC, Facultat de Ciencies, Campus UAB, 08193 Bellaterra (Spain)

    2007-05-15

    We have computed the gravitational wave emission arising from the coalescence of binary systems composed of a white dwarf and a neutron star. In order to do so, we have followed the evolution of such systems using a Smoothed Particle Hydrodynamics code. Here we present some of the results obtained so far, paying special attention to the detectability of the emitted gravitational waves. Within this context, we show which could be the impact of individual merging episodes for LISA.

  1. Neutron radiation of an electronic sensor using coincidence method for an active dosimeter

    CERN Document Server

    Ndoye, A; Barelaud, B; Celerier, A; Decossas, J L; Vareille, J C

    1999-01-01

    Results on the modeling and experimentation on a preliminary structure to be used in neutron dosimetry are presented. The structure consists of a thin reactive layer deposited on two facing diodes. The sensor has been developed mainly to solve the problem of neutron dosimetry in the intermediate energy range (0.5 eV to 500 keV) for which the existing electronic systems are ineffective. The use of a coincidence method for the detection of the nuclear reaction products allows the discrimination of the gamma interactions. The system can also be used down to thermal energies for which the sensitivity is considerably higher. The sensor response depends on the thickness of the reactive layer which defines the neutron sensitivity and has an influence on the slowing down and absorption of emitted particles, the depletion layer which has to be optimized for a given energy range, the thickness of the dead layer of each detector. For experimentations with an Am-Be source, we have chosen following parameters: 100 nm for ...

  2. Study of the thermal neutron radiative capture sup 31 P( n ,. gamma. ) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Xiantang; Shi Zongren; Zhang Ming; Li Guohua; Ding Dazhao (Institute of Atomic Energy, P. O. Box 275, Beijing (CN))

    1989-05-01

    The measurement of the {gamma}-ray spectrum of the {sup 31}P({ital n},{gamma}) reaction induced by thermal neutrons from the heavy water reactor is performed by using three crystal pair spectrometer'', Ge(Li) and HPGe detectors. 128 {gamma}-rays are identified, 24 of them are recognized as primary {gamma}-transitions. The excitation energies of 32 levels are deduced. Two possible levels of 5451.44 keV and 5021.10 keV have not been reported previously. The neutron separation energy is determined to be 7936.65(8) keV and partial cross sections are measured. The thermal neutron capture cross section of {sup 31}P is obtained to be 177(5) mb by comparison with Au({ital n}{sub th}, {gamma}) cross section standard. With the formula of the Lane-Lynn direct interaction, the partial capture cross sections of eight strong primary E1-transitions are calculated and compared with their experimental values, leading to the conclusion that the theoretical values are in coincidence with the experimental ones and the E1-transitions mainly come from 1+ capture state. The correlation analyses of the reduced strengths of E1 and M1 transitions with the spectroscopic factors of (d, p) reaction are performed and the reaction mechanisms discussed.

  3. Self-consistent calculations of the strength function and radiative neutron capture cross section for stable and unstable tin isotopes

    CERN Document Server

    Goriely, S; Krewald, S

    2011-01-01

    The E1 strength function for 15 stable and unstable Sn even-even isotopes from A=100 till A=176 are calculated using the self-consistent microscopic theory which, in addition to the standard (Q)RPA approach, takes into account the single-particle continuum and the phonon coupling. Our analysis shows two distinct regions for which the integral characteristics of both the giant and pygmy resonances behave rather differently. For neutron-rich nuclei, starting from $^{132}$Sn, we obtain a giant E1 resonance which significantly deviates from the widely-used systematics extrapolated from experimental data in the $\\beta$-stability valley. We show that the inclusion of the phonon coupling is necessary for a proper description of the low-energy pygmy resonances and the corresponding transition densities for $A132$ region the influence of phonon coupling is significantly smaller. The radiative neutron capture cross sections leading to the stable $^{124}$Sn and unstable $^{132}$Sn and $^{150}$Sn nuclei are calculated wi...

  4. Neutron Radiation Affects the Expression of Genes Involved in the Response to Auxin, Senescence and Oxidative Stress in Arabidopsis

    Science.gov (United States)

    Fortunati, A.; Tassone, P.; Migliaccio, F.

    2008-06-01

    Researches were conducted on the effect of neutron radiation on the expression of genes auxin activated or connected with the process of senescence in Arabidopsis plants. The research was done by applying the real-time polymerase chain reaction (PCR) technique. The results indicated that the auxin response factors (ARFs) genes are clearly downregulated, whereas the indolacetic acid-induced (Aux/IAAs) genes in some cases were upregulated. By contrast in the mutants for auxin transport aux1 and eir1 the ARFs genes were upregulated. In addition, both in the wildtype and mutants, some already known genes activated by stress and senescence were significantly upregulated. On the basis of these researches we conclude that the process of senescence induced by irradiation is, at least in part, controlled by the physiology of the hormone auxin.

  5. Competition between radiative and strong force decay

    Science.gov (United States)

    Tabor, Samuel

    2017-01-01

    For nuclear states unbound to neutron decay, radiative emission is often assumed to not dominate over neutron decay mediated by the far stronger strong interaction, except for very low neutron energies and high angular momentum barriers. Recent experimental investigations of 19O and 27 Mg populated in heavy-ion fusion-evaporation reactions have revealed predominantly gamma decays from a number of states unbound to neutron decay by up to 2 MeV. In most cases the angular momentum barrier is not sufficient to inhibit neutron decay enough to allow E-M decay with widths of up to an eV or so to win. Other inhibitions to particle decay, including low spectroscopic factors, will be discussed. Supported in part by NSF Grant No. 1401574.

  6. [Malignant transformation of human fibroblasts by neutrons and by gamma radiation: Relationship to mutations induced

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    A brief overview if provided of selected reports presented at the International Symposium on Molecular Mechanisms of Radiation- and Chemical Carcinogen-Induced Cell Transformation held at Mackinac Island, Michigan on September 19-23, 1993.

  7. Polarised Small Angle Neutron Scattering study of microstructural radiation damage in steels for nuclear applications

    Energy Technology Data Exchange (ETDEWEB)

    Coppola, R. [ENEA-Casaccia, FIS, CP 2400, 00100 Rome (Italy)]. E-mail: coppolar@casaccia.enea.it; Lindau, R. [Forschungszentrum Karlsruhe, IMF, P.O. Box 3640, D-76021 Karlsruhe (Germany); Magnani, M. [ENEA-Clementel, FIS, V. Don Fiammelli 2, 40129 Bologna (Italy); May, R.P. [Institut Max Von Laue-Paul Langevin, 6 rue Jules Horowitz, F-38042 Grenoble Cedex (France); Moeslang, A. [Forschungszentrum Karlsruhe, IMF, P.O. Box 3640, D-76021 Karlsruhe (Germany); Valli, M. [ENEA-Clementel, FIS, V. Don Fiammelli 2, 40129 Bologna (Italy)

    2006-11-15

    Polarised SANS has been used to investigate two martensitic steels for fusion reactor technology (MANET and OPTIFER, differing in their initial Cr content), before and after neutron irradiation. The measurements were carried out at the instrument D22 of the ILL, Grenoble, using an ad hoc polarised beam set-up. The results show both the occurrence of Cr redistribution phenomena with correlated changes in the composition of the precipitate phases, and the growth of non-magnetic defects (possibly microvoids), depending on the irradiation conditions and on the original steel composition.

  8. Polarised Small Angle Neutron Scattering study of microstructural radiation damage in steels for nuclear applications

    Science.gov (United States)

    Coppola, R.; Lindau, R.; Magnani, M.; May, R. P.; Möslang, A.; Valli, M.

    2006-11-01

    Polarised SANS has been used to investigate two martensitic steels for fusion reactor technology (MANET and OPTIFER, differing in their initial Cr content), before and after neutron irradiation. The measurements were carried out at the instrument D22 of the ILL, Grenoble, using an ad hoc polarised beam set-up. The results show both the occurrence of Cr redistribution phenomena with correlated changes in the composition of the precipitate phases, and the growth of non-magnetic defects (possibly microvoids), depending on the irradiation conditions and on the original steel composition.

  9. All-sky upper limit for gravitational radiation from spinning neutron stars

    CERN Document Server

    Astone, P; Bassan, M; Borkowski, K M; Coccia, E; D'Antonio, S; Fafone, V; Giordano, G; Jaranowski, P; Królak, A; Marini, A; Modena, Y M I; Modestino, G; Moleti, A; Pallottino, G V; Pietka, M; Quintieri, G P L; Rocchi, A; Ronga, F; Terenzi, R; Visco, M

    2003-01-01

    We present results of the all-sky search for gravitational-wave signals from spinning neutron stars in the data of the EXPLORER resonant bar detector. Our data analysis technique was based on the maximum likelihood detection method. We briefly describe the theoretical methods that we used in our search. The main result of our analysis is an upper limit of ${\\bf 2\\times10^{-23}}$ for the dimensionless amplitude of the continuous gravitational-wave signals coming from any direction in the sky and in the narrow frequency band from 921.00 Hz to 921.76 Hz.

  10. Aspects of ultra-cold neutron production in radiation fields at the FRM II

    Energy Technology Data Exchange (ETDEWEB)

    Wlokka, Stephan Albrecht

    2016-08-17

    Neutrons are called ''ultra-cold'', if they are reflected by a material surface under all angles of incident. They can then be stored for long times (ca. 1000s). In the new UCN source at the FRM II, Deuterium will be used to produce the UCN. Its behaviour under irradiation was investigated. Additionally the transport properties of new UCN guides were tested. Also, the helium-3 content of purified helium samples was examined, because using this type of helium greatly reduces the tritium production when used at the reactor.

  11. Effect of selective area growth mask width on multi-quantum-well electroabsorption modulated lasers investigated by synchrotron radiation X-ray microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Mino, Lorenzo, E-mail: lorenzo.mino@unito.it [Department of Inorganic, Materials and Physical Chemistry, NIS Centre of Excellence and INSTM Unit, University of Turin, Via P. Giuria 7, I-10125 Turin (Italy); Agostino, Angelo [Department of General and Organic Chemistry, NIS Centre of Excellence, University of Turin, C.so Massimo D' Azeglio 48, I-10125 Turin (Italy); Codato, Simone [Avago Technologies Italy S.r.l., Torino Technology Centre, Via G. Schiaparelli 12, 10148 Turin (Italy); Martinez-Criado, Gema [ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble CEDEX (France); Lamberti, Carlo [Department of Inorganic, Materials and Physical Chemistry, NIS Centre of Excellence and INSTM Unit, University of Turin, Via P. Giuria 7, I-10125 Turin (Italy)

    2012-08-01

    High performance optoelectronic devices require monolithic integration of different functions at chip level. This is the case of multi-quantum well (MQW) electroabsorption modulated laser (EML), employed in long-distance, high-frequency optical fiber communication applications, which is realized exploiting the selective area growth (SAG) technique. Optimization of the growth parameters is carried out by empirical approaches since a direct characterization of the MQW is not possible with laboratory X-ray sources, owing to the micrometer-variation of composition and thickness inherent to the SAG technique. In this work we combined micrometer-resolved photoluminescence with synchrotron radiation micrometer-resolved X-ray fluorescence to study the effect of different SAG masks on the electronic properties and chemical composition of the SAG MQW EML device.

  12. Development And Implementation Of Photonuclear Cross-section Data For Mutually Coupled Neutron-photon Transport Calculations In The Monte Carlo N-particle (mcnp) Radiation Transport Code

    CERN Document Server

    White, M C

    2000-01-01

    The fundamental motivation for the research presented in this dissertation was the need to development a more accurate prediction method for characterization of mixed radiation fields around medical electron accelerators (MEAs). Specifically, a model is developed for simulation of neutron and other particle production from photonuclear reactions and incorporated in the Monte Carlo N-Particle (MCNP) radiation transport code. This extension of the capability within the MCNP code provides for the more accurate assessment of the mixed radiation fields. The Nuclear Theory and Applications group of the Los Alamos National Laboratory has recently provided first-of-a-kind evaluated photonuclear data for a select group of isotopes. These data provide the reaction probabilities as functions of incident photon energy with angular and energy distribution information for all reaction products. The availability of these data is the cornerstone of the new methodology for state-of-the-art mutually coupled photon-neutron tran...

  13. A Preliminary Assessment of Radiation and Air Activation for the Neutron Science Facility in RAON

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S. C.; Lee, C. W.; Lee, E. J.; Lee, Y. O. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, J. C. [Institute for Basic Science, Daejeon (Korea, Republic of)

    2015-05-15

    The works will stay in the DAQ room during an operation for about 1 month. In order to test the characteristics of the detector, the workers are also possible to access the TOF hall after a shutdown. Therefore, the shielding analysis of the NSF is required to meet the above purpose. In view of this, we performed the calculation of the shielding concrete thickness required for a target room by using MCNPX code with a neutron source obtained from Institute for Basic Science (IBS). In addition, the dose distribution and air activation for the entire space in NSF were evaluated using MCNPX and SP-FISPACT 2010 codes. We have performed the shielding calculation with the neutron source produced from the C(d,n) reactions. The concrete thickness was evaluated for all directions of the target room, and it was confirmed by performing the calculation of dose distribution to the entire space. However, the dose rate for the beam line was high. The radioactivity of radionuclides at TOF hall do not exceeded the air concentration and release limits.

  14. Proton and neutron test facilities at 1 GeV synchrocyclotron of PNPI for radiation resistance testing of avionic and space electronics

    Directory of Open Access Journals (Sweden)

    Ivanov Evgeniy M.

    2017-01-01

    Full Text Available A description of the proton (IS SC-1000, IS OP-1000 and neutron (IS NP/GNEIS test facilities at the 1 GeV synchrocyclotron SC-1000 of the PNPI used for radiation resistance testing of electronic components and systems intended for avionic and space research is presented. A unique conjunction of proton beams with variable energy 100–1000 MeV and atmospheric like neutron beam with broad energy range (1–1000 MeV spectrum enables to perform complex testing of the semiconductor electronic devices within a single testing cycle.

  15. Neutron generator for the array borehole logging

    Institute of Scientific and Technical Information of China (English)

    LuHong-Bo; ZhongZhen-Qian; 等

    1998-01-01

    The performance mechanism of the array neutron generator to be used to porosity logging is presented.The neutron generator utilizes a drive-in target ceramic neutron tube,which cursts nerutron with fast-slow period selectively pressure.Regulation of the neutron tube is accomplished by pulse width modulation.The high voltage power supply is poerated at optimum frequency.

  16. Some remarks on in-situ studies using TEM-heavy-ion accelerator link from the stand point of extracting radiation damage caused by fast neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Ishino, Shiori, E-mail: ishino@k9.dion.ne.jp [University of Tokyo, Bunkyo-ku, Tokyo, 113-8656 (Japan); Sekimura, Naoto [Department of Nuclear Engineering and Management, University of Tokyo, Bunkyo-ku, Tokyo, 113-8656 (Japan); Murakami, Kenta [Nuclear Professional School, University of Tokyo, Tokai-mura, Naka-gun, Ibaraki, 319-1194 (Japan); Abe, Hiroaki [Institute of Materials Research, Tohoku University, Aoba-ku, Sendai, 980-8577 (Japan)

    2016-04-01

    Radiation damage of materials for fission and fusion reactors has been scaled in terms of the number of displacements per atoms (dpa). The method of evaluating the dpa has been established and standardized. However, it has become obvious that more detailed analyses are required, particularly for the nature and spatial distribution of the introduced point defects and their clusters. Such detailed nature of the defects introduced is thought to be governed by the primary knock-on atom (PKA) spectrum, A number of trials to elucidate the PKA dependent radiation effects by choosing the mass and energy of the incident ions have been explored. In some cases, defect formation by a single impinging ion has been observed. However, it has also been recognized that there are a number of artefacts arising from energy deposition distributions, existence of surface sinks together with radiation induced surface modifications and so on. In this paper, discussion will be made on how to establish irradiation correlation between neutron and heavy ion irradiations in a cascade damage formation regime. For the past fifty years, the correlation between neutron and ion irradiations from the view point of simulating the neutron radiation damage by ion irradiations has been discussed many times. However, the correlation itself has not been fully discussed separately. This is the major objective of this paper.

  17. The use of symbolic computation in radiative, energy, and neutron transport calculations. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Frankel, J.I.

    1997-09-01

    This investigation used sysmbolic manipulation in developing analytical methods and general computational strategies for solving both linear and nonlinear, regular and singular integral and integro-differential equations which appear in radiative and mixed-mode energy transport. Contained in this report are seven papers which present the technical results as individual modules.

  18. Study of the angular energy distribution of secondary gamma radiation resulting from interactions of reactor neutrons with iron and lead barriers

    Energy Technology Data Exchange (ETDEWEB)

    Makarious, A.S.; Maayouf, R.M.A.; Megahid, R.M. (Atomic Energy Establishment, Inshas (Egypt))

    1980-07-01

    The present work deals with the experimental study of the angular energy distributions of the secondary gamma-radiation resulting from interaction of reactor neutrons with iron and lead barriers of infinite diameters and of 5 cm thickness. The measurements were carried out both with the bare neutron beam, emitted from the ET-RR-1 reactor, and with the beam being transmitted through a B/sub 4/C filter. The pulse height distributions of gamma-rays, emitted from the used barriers, were measured with a gamma-ray spectrometer with a single stilbene scintillator. The experimental results were compared with theoretical calculations carried out using a multigroup coupled neutron gamma cross-sections and a discrete ordinates transport theory code. The comparison shows a reasonable agreement between both experimental results and theoretical calculations.

  19. Constraints on Thermal X-ray Radiation from SAX J1808.4-3658 and Implications for Neutron Star Neutrino Emission

    CERN Document Server

    Heinke, C O; Wijnands, R; Taam, R E

    2006-01-01

    Thermal X-ray radiation from neutron star soft X-ray transients in quiescence provides the strongest constraints on the cooling rates of neutron stars, and thus on the interior composition and properties of matter in the cores of neutron stars. We analyze new (2006) and archival (2001) XMM-Newton observations of the accreting millisecond pulsar SAX J1808.4-3658 in quiescence, which provide the most stringent constraints to date. The X-ray spectrum of SAX J1808.4-3658 in the 2006 observation is consistent with a power-law of photon index 1.83\\pm0.16, without requiring the presence of a blackbody-like component from a neutron star atmosphere. Our 2006 observation shows a slightly lower 0.5-10 keV X-ray luminosity, at a level of 68^{+15}_{-13}% that inferred from the 2001 observation. Simultaneous fitting of all available XMM data allows a constraint on the quiescent bolometric (0.01-10 keV) neutron star luminosity of L_{q,bol}<1.1*10^{31} erg/s. This limit excludes some current models of neutrino emission me...

  20. Measurement of the radiative neutron capture cross section of 206Pb and its astrophysical implications

    CERN Document Server

    Domingo-Pardo, C; Aerts, G; Alvarez, H; Alvarez-Velarde, F; Andriamonje, Samuel A; Andrzejewski, J; Assimakopoulos, Panayiotis; Audouin, L; Badurek, G; Baumann, P; Becvar, F; Berthoumieux, E; Bisterzo, S; Calviño, F; Calviani, M; Cano-Ott, D; Capote, R; Carrapico, C; Cennini, P; Chepel, V; Chiaveri, Enrico; Colonna, N; Cortés, G; Couture, A; Cox, J; Dahlfors, M; David, S; Dillman, I; Dolfini, R; Dridi, W; Durán, I; Eleftheriadis, C; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Fitzpatrick, L; Frais-Kölbl, H; Fujii, K; Furman, W; Gallino, R; Gonçalves, I; Gonzalez-Romero, E; Goverdovski, A; Gramegna, F; Griesmayer, E; Guerrero, C; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martínez, A; Igashira, M; Isaev, M; Jericha, E; Kappeler, F; Kadi, Y; Karadimos, D; Karamanis, D; Kerveno, M; Ketlerov, V; Köhler, P; Konovalov, V; Kossionides, E; Krticka, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Massimi, C; Mastinu, P; Mengoni, A; Milazzo, P M; Moreau, C; Mosconi, M; Neves, F; Oberhummer, Heinz; Oshima, M; O'Brien, S; Pancin, J; Papachristodoulou, C; Papadopoulos, C; Paradela, C; Patronis, N; Pavlik, A; Pavlopoulos, P; Perrot, L; Plag, R; Plompen, A; Plukis, A; Poch, A; Pretel, C; Quesada, J; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, Carlo; Rudolf, G; Rullhusen, P; Salgado, J; Sarchiapone, L; Savvidis, I; Stéphan, C; Tagliente, G; Taín, J L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarín, D; Vincente, M C; Vlachoudis, V; Vlastou, R; Voss, F; Walter, S; Wendler, H; Wiescher, M; Wisshak, K

    2007-01-01

    The (n, gamma) cross section of 206Pb has been measured at the CERN n_TOF facility with high resolution in the energy range from 1 eV to 600 keV by using two optimized C6D6 detectors. In the investigated energy interval about 130 resonances could be observed, from which 61 had enough statistics to be reliably analyzed via the R-matrix analysis code SAMMY. Experimental uncertainties were minimized, in particular with respect to (i) angular distribution effects of the prompt capture gamma-rays, and to (ii) the TOF-dependent background due to sample-scattered neutrons. Other background components were addressed by background measurements with an enriched 208Pb sample. The effect of the lower energy cutoff in the pulse height spectra of the C6D6 detectors was carefully corrected via Monte Carlo simulations. Compared to previous 206Pb values, the Maxwellian averaged capture cross sections derived from these data are about 20% and 9% lower at thermal energies of 5 keV and 30 keV, respectively. These new results hav...

  1. Characterization of radiation induced defects in EUROFER 97 after neutron irradiation

    Science.gov (United States)

    Klimenkov, M.; Materna-Morris, E.; Möslang, A.

    2011-10-01

    Specimens of EUROFER 97 prepared for impact tests have been irradiated to an average dose of 16.3 dpa at irradiation temperatures of 250-450 °C. TEM investigations have been performed to study radiation induced changes in the microstructure. The characterization and statistical analysis show the temperature dependant formation of small dislocation loops and He bubbles. The Burgers vector of dislocation loops was ½. A novel feature is that within statistical uncertainty the maximum in the dislocation density observed around 300 °C decreased with decreasing irradiation temperature down to 250 °C. The TEM data are correlated with tensile and instrumented Charpy test results.

  2. Evaluation of individual dosimetry in mixed neutron and photon radiation fields (EVIDOS). Part I: Scope and methods of the project.

    Science.gov (United States)

    d'Errico, F; Bartlett, D; Bolognese-Milsztajn, T; Boschung, M; Coeck, M; Curzio, G; Fiechtner, A; Kyllönen, J-E; Lacoste, V; Lindborg, L; Luszik-Bhadra, M; Reginatto, M; Schuhmacher, H; Tanner, R; Vanhavere, F

    2007-01-01

    Supported by the European Commission, the EVIDOS project started in November 2001 with the broad goal of evaluating state of the art dosimetry techniques in representative workplaces of the nuclear industry. Seven European institutes joined efforts with end users at nuclear power plants, at fuel processing and reprocessing plants, and at transport and storage facilities. A comprehensive programme was devised to evaluate capabilities and limitations of standard and innovative personal dosemeters in relation to the mixed neutron-photon fields of concern to the nuclear industry. This paper describes the criteria behind the selection of dosimetry techniques and workplaces that were analysed, as well as the organisation of the measurement campaigns. Particular emphasis was placed on the evaluation of a variety of electronic personal dosemeters, either commercially available or previously developed by the partners. The estimates provided by these personal dosemeters were compared to reference values of dose equivalent quantities derived from spectrometry and fluence-to-dose equivalent conversion coefficients. Spectrometry was performed both with conventional multisphere and with some original instrumentation providing energy and direction resolution, based on silicon detectors and superheated drop detectors mounted on or in spherical moderators. The results were collected in a large, searchable database and are intended to be used in the harmonisation of dosimetric procedures for mixed radiation fields and for the approval of dosimetry services in Europe.

  3. Radiation resistance and parameters of activation of aluminium-magnesium-scandium and aluminium-magnesium-vanadium alloys under neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, L.I.; Ivanov, V.V.; Lazorenko, V.M.; Platov, Yu.M.; Tovtin, V.I.; Toropova, L.S. (A.A. Baikov Inst. of Metallurgy, Academy of Sciences, Moscow (Russia))

    1992-09-01

    Alloys Al-2.24Mg-0.223Sc-0.04Zr, Al-2.24Mg-0.12Sc-0.04Zr, and Al-2.24Mg-0.05V (at.%) annealed at 150deg C and 400deg C were irradiated at [approx equal] 70 and [approx equal] 150deg C in the SM-2 reactor. The maximum neutron fluence was 4.7x10[sup 24] m[sup -2] (E > 0.1 MeV). The tensile tests were carried out in the temperature range 20 to 350deg C. Alloy Al-2.24 Mg-0.23Sc-0.04Zr annealed at 400deg C and alloy Al-2.24Mg-0.12Sc-0.04Zr annealed at 150deg C at all test temperatures retained good mechanical properties after irradiation. The mechanisms for the radiation resistance of aluminium-scandium and aluminium-magnesium-scandium alloys are discussed. Calculations of induced radioactivity and its decay behaviour after shutdown in aluminium and Al-2.24Mg-(0.12-0.23)Sc alloys were carried out. Composition of the radionuclides in these materials after irradiation in the SM-2 reactor were also determined using a gamma-spectroscopy technique. (orig.).

  4. Radiation resistance and parameters of activation of aluminium-magnesium-scandium and aluminium-magnesium-vanadium alloys under neutron irradiation

    Science.gov (United States)

    Ivanov, L. I.; Ivanov, V. V.; Lazorenko, V. M.; Platov, Yu. M.; Tovtin, V. I.; Toropova, L. S.

    1992-09-01

    Alloys Al2.24Mg0.23Sc0.04Zr, Al2.24Mg0.12Sc0.04Zr, and Al2.24Mg0.05V (at.)) annealed at 150°C and 400°C were irradiated ≈70 and ≈150°C in the SM-2 reactor. The maximum neutron fluence was 4.7×1024 m-2 (E > 0.1 MeV). The tensile tests were carried out in the temperature range 20 to 350°C. Alloy Al2.24Mg0.23Sc0.04Zr annealed at 400°C and alloy Al2.24Mg0.12Sc0.04Zr annealed at 150°C at all test temperature, retained good mechanical properties after irradiation. The mechanisms for the radiation resistance of aluminiumscandium and aluminiummagnesiumscandium alloys are discussed. Calculations of induced radioactivity and its decay behaviour after shutdown in aluminium and Al2.24Mg(0.12-0.23)Sc alloys were carried out. Composition of the radionuclides in these materials after irradiation in the SM-2 reactor were also determined using a gamma-spectroscopy technique.

  5. 21 CFR 1000.15 - Examples of electronic products subject to the Radiation Control for Health and Safety Act of 1968.

    Science.gov (United States)

    2010-04-01

    ... radiation, electrons, neutrons, and other particulate radiation include: Ionizing electromagnetic radiation... radiation and ionizing electromagnetic radiation: Electron microscopes. Neutron generators. (b) Examples...

  6. Neutronic Reactor Shield

    Science.gov (United States)

    Fermi, Enrico; Zinn, Walter H.

    The argument of the present Patent is a radiation shield suitable for protection of personnel from both gamma rays and neutrons. Such a shield from dangerous radiations is achieved to the best by the combined action of a neutron slowing material (a moderator) and a neutron absorbing material. Hydrogen is particularly effective for this shield since it is a good absorber of slow neutrons and a good moderator of fast neutrons. The neutrons slowed down by hydrogen may, then, be absorbed by other materials such as boron, cadmium, gadolinium, samarium or steel. Steel is particularly convenient for the purpose, given its effectiveness in absorbing also the gamma rays from the reactor (both primary gamma rays and secondary ones produced by the moderation of neutrons). In particular, in the present Patent a shield is described, made of alternate layers of steel and Masonite (an hydrolized ligno-cellulose material). The object of the present Patent is not discussed in any other published paper.

  7. From the Coulomb breakup of halo nuclei to neutron radiative capture

    CERN Document Server

    Capel, Pierre

    2016-01-01

    Coulomb breakup is used to infer radiative-capture cross sections at astrophysical energies. We test theoretically the accuracy of this indirect technique in the particular case of 15C, for which both the Coulomb breakup to ^{14}C+n and the radiative capture 14C(n,{\\gamma})15C have been measured. We analyse the dependance of Coulomb-breakup calculations on the projectile description in both its initial bound state and its continuum. Our calculations depend not only on the Asymptotic Normalisation Coefficient (ANC) of the 15C ground state, but also on the 14C-n continuum. This questions the method proposed by Summers and Nunes [Phys. Rev. C 78, 011601 (2008), ibid. 78, 069908 (2008)], which assumes that an ANC can be directly extracted from the comparison of calculations to breakup data. Fortunately, the sensitivity to the continuum description can be absorbed in a normalisation constant obtained by a simple {\\chi}2 fit of our calculations to the measurements. By restricting this fit to low 14C-n energy in the...

  8. Near-Core and In-Core Neutron Radiation Monitors for Real Time Neutron Flux Monitoring and Reactor Power Level Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Douglas S. McGregor; Marvin L. Adams; Igor Carron; Paul Nelson

    2006-06-12

    MPFDs are a new class of detectors that utilize properties from existing radiation detector designs. A majority of these characteristics come from fission chamber designs. These include radiation hardness, gamma-ray background insensitivity, and large signal output.

  9. Influence of the neutron transport tube on neutron resonance densitometry

    Directory of Open Access Journals (Sweden)

    Kitatani Fumito

    2017-01-01

    Full Text Available Neutron Resonance Densitometry (NRD is a non-destructive assay technique of nuclear materials in particle-like debris that contains various materials. An aim of NRD is to quantify nuclear materials in a melting fuel of Fukusima Daiichi plant, spent nuclear fuel and annihilation disposal fuel etc. NRD consists of two techniques of Neutron Resonance Transmission Analysis (NRTA and Neutron Resonance Capture Analysis (NRCA or Prompt Gamma-ray Analysis (PGA. A density of nuclear material isotopes is decided with NRTA. The materials absorbing a neutron in a wide energy range such as boron in a sample are identified by NRCA/PGA. The information of NRCA/PGA is used in NRTA analysis to quantify nuclear material isotopes. A neutron time of flight (TOF method is used in NRD measurements. A facility, consisting of a neutron source, a neutron flight path, and a detector is required. A short flight path and a strong neutron source are needed to downsize such a facility and put NRD into practical use. A neutron transport tube covers a flight path to prevent noises. In order to investigate the effect of neutron transport tube and pulse width of a neutron source, we carried out NRTA experiments with a 2-m short neutron transport tube constructed at Kyoto University Research Reactor Institute - Linear Accelerator (KURRI-LINAC, and impacts of shield of neutron transport tube and influence of pulse width of a neutron source were examined. A shield of the neutron transport tube reduced a background and had a good influence on the measurement. The resonance dips of 183W at 27 eV was successfully observed with a pulse width of a neutron source less than 2 μs.

  10. Safety techniques in the change of nuclear systems. Radiation protection at spallation neutron sources and transmutation facilities; Sicherheitstechnik im Wandel Nuklearer Systeme. Strahlenschutz bei Spallationsneutronenquellen und Transmutationsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Nuenighoff, Kay

    2009-07-01

    To push the boundary towards higher neutron fluxes concepts based on spallation reactions have been discussed. Here neutrons are produced by bombarding a heavy metal target (e.g. mercury, tungsten, or tantalum) with high energetic protons. Up to now such facilities could not be realised because of the high power particle accelerators needed. Recent developments of the accelerator technology open the possibility of construction and operating proton accelerators in the MW region. This is demonstrated by construction and commissioning of two MW spallation neutron sources, namely SNS (Oak Ridge, Tennessee, USA) with a power of 1.4 MW and J-PARC (Japan) with 1 MW. The realisation of proton accelerators at this power level will open the way towards energy amplifiers, as proposed e.g. by Carlo Rubbia. Such a facility will not only produce electric power. Furthermore longliving radionuclides can be transmutated into shortlived or even stable nuclides by neutron induced nuclear reactions. A mitigation of the problem of nuclear waste disposal. The above discussed developments prove that accelerators are not only constructed for research, moreover application of these technology became state of the art. With the emergence of particle accelerators in the MW region, radiation protection is confronted with new kind of problems to be solved. Especially the higher kinetic energies of the primary beam particles requires modification and expansion of computer programs well known in nuclear engineering. In contrast to nuclear reactors with kinetic energies up to 2-3 MeV, in spallation reaction secondary particles up to the incident energy in the GeV region will be produced. Problems related to radiation protection have to be considered in an energy range three orders of magnitude higher than known from nuclear reactors. In this thesis existing computer codes are compared and validated with data from selected experiments. Questions concerning radiation protection covers a broad range

  11. Level Width Broaden Effect

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing-Shang

    2004-01-01

    In fitting the double-differential measurements thelevelwidth broadening effect should be taken into account properly due to Heisenberg uncertainty.Besides level width broadening effect the energy resolution in the measurements is also needed in this procedure.In general,the traditional normal Gaussian expansion is employed.However,the research indicates that to do so in this way the energy balance could not hold.For this reason,the deformed Gaussian expansion functions with exponential form for both the single energy point and continuous spectrum are introduced,with which the normalization and energy balance conditions could hold exactly in the analytical form.

  12. Improvements in apparatus and procedures for using an organic liquid scintillator as a fast-neutron spectrometer for radiation protection applications

    Energy Technology Data Exchange (ETDEWEB)

    Thorngate, J.H.

    1987-05-15

    For use in radiation protection measurements, a neutron spectrometer must have a wide energy range, good sensitivity, medium resolution, and ease of taking and reducing data. No single spectrometer meets all of these requirements. Several experiments aimed at improving and characterizing the detector response to gamma rays and neutrons were conducted. A light pipe (25 mm) was needed between the scintillator cell and the photomultiplier tube to achieve the best resolution. The light output of the scintillator as a function of gamma-ray energy was measured. Three experiments were conducted to determine the light output as a function of neutron energy. Monte Carlo calculations were made to evaluate the effects of multiple neutron scattering and edge effects in the detector. The electronic systems associated with the detector were improved with a transistorized circuit providing the bias voltage for the photomultiplier tube dynodes. This circuit was needed to obtain pulse-height linearity over the wide range of signal sizes. A special live-time clock was built to compensate for the large amount of dead time generated by the pulse-shape discrimination circuit we chose to use. 64 refs., 58 figs., 9 tabs.

  13. Neutron tomography

    Science.gov (United States)

    Crump, James C., III; Richards, Wade J.; Shields, Kevin C.

    1995-07-01

    The McClellan Nuclear Radiation Center's (MNRC) staff in conjunction with a Cooperative Research and Development Agreement (CRDA) with the U.C. Santa Barbara facility has developed a system that can be used for aircraft inspection of jet engine blades. The problem was to develop an inspection system that can detect very low concentrations of hydrogen (i.e., greater than 100 ppm) in metal matricies. Specifically in Titanium alloy jet engine blades. Entrapment and precipitation of hydrogen in metals is an undesirable phenomenon which occurs in many alloys of steel and titanium. In general, metals suffer a loss of mechanical properties after long exposures to hydrogen, especially at high temperatures and pressures, thereby becoming embrittled. Neutron radiography has been used as a nondestructive testing technique for many years. Neutrons, because of their unique interactions with materials, are especially useful in the detection of hydrogen. They have an extremely high interaction cross section for low atomic number nuclei (i.e., hydrogen). Thus hydrogen in a metal matrix can be visualized using neutrons. Traditional radiography is sensitive to the total attenuation integrated over the path of radiation through the material. Increased sensitivity and quantitative cross section resolution can be obtained using three-dimensional volumetric imaging techniques such as tomography. The solution used to solve the problem was to develop a neutron tomography system. The neutron source is the McClellan Nuclear Radiation Center's 1 MW TRIGA reactor. This paper describes the hardware used in the system as well as some of the preliminary results.

  14. A High Temperature-Tolerant and Radiation-Resistant In-Core Neutron Sensor for Advanced Reactors. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Lei [The Ohio State Univ., Columbus, OH (United States); Miller, Don [The Ohio State Univ., Columbus, OH (United States)

    2015-01-23

    The objectives of this project are to develop a small and reliable gallium nitride (GaN) neutron sensor that is capable of withstanding high neutron fluence and high temperature, isolating gamma background, and operating in a wide dynamic range. The first objective will be the understanding of the fundamental materials properties and electronic response of a GaN semiconductor materials and device in an environment of high temperature and intense neutron field. To achieve such goal, an in-situ study of electronic properties of GaN device such as I-V, leakage current, and charge collection efficiency (CCE) in high temperature using an external neutron beam will be designed and implemented. We will also perform in-core irradiation of GaN up to the highest yet fast neutron fluence and an off-line performance evaluation.

  15. Influence of the gamma-ray fraction in the reactor radiation on the total signal of a self-powered neutron detector

    Science.gov (United States)

    Kurchenkov, A. Yu.; Kulakov, A. S.; Alekseev, N. I.; Kalinushkin, A. E.

    2013-12-01

    For controlling the linear power density in the reactor core, the Khortitsa-M software program as a part of the in-core instrumentation system (ICIS) employs only self-powered neutron detector (SPND) data with the neutronic calculation for the consistent determination of the power density in unmeasurable fuel assemblies (FAs). The confidence of the interpretation of the SPND data essentially determines the safe and efficient operation of a reactor. Previously, it was assumed that the gamma-ray fraction in the reactor radiation does not exceed one percent and is independent of the fuel enrichment and the FA and SPND burnups. Since it is difficult to estimate the contribution of the reactor gamma radiation to the SPND current experimentally, in this work, we present a calculated estimate using modern software and libraries of constants. On the basis of the results of this study, the question is discussed whether it is appropriate to take into account the reactor gamma radiation in the transfer function from the SPND current to the power density of six fuel elements surrounding the SPND with allowance for both the type of FA and the FA and SPND burnups.

  16. Intense fusion neutron sources

    Science.gov (United States)

    Kuteev, B. V.; Goncharov, P. R.; Sergeev, V. Yu.; Khripunov, V. I.

    2010-04-01

    The review describes physical principles underlying efficient production of free neutrons, up-to-date possibilities and prospects of creating fission and fusion neutron sources with intensities of 1015-1021 neutrons/s, and schemes of production and application of neutrons in fusion-fission hybrid systems. The physical processes and parameters of high-temperature plasmas are considered at which optimal conditions for producing the largest number of fusion neutrons in systems with magnetic and inertial plasma confinement are achieved. The proposed plasma methods for neutron production are compared with other methods based on fusion reactions in nonplasma media, fission reactions, spallation, and muon catalysis. At present, intense neutron fluxes are mainly used in nanotechnology, biotechnology, material science, and military and fundamental research. In the near future (10-20 years), it will be possible to apply high-power neutron sources in fusion-fission hybrid systems for producing hydrogen, electric power, and technological heat, as well as for manufacturing synthetic nuclear fuel and closing the nuclear fuel cycle. Neutron sources with intensities approaching 1020 neutrons/s may radically change the structure of power industry and considerably influence the fundamental and applied science and innovation technologies. Along with utilizing the energy produced in fusion reactions, the achievement of such high neutron intensities may stimulate wide application of subcritical fast nuclear reactors controlled by neutron sources. Superpower neutron sources will allow one to solve many problems of neutron diagnostics, monitor nano-and biological objects, and carry out radiation testing and modification of volumetric properties of materials at the industrial level. Such sources will considerably (up to 100 times) improve the accuracy of neutron physics experiments and will provide a better understanding of the structure of matter, including that of the neutron itself.

  17. Development and Implementation of Photonuclear Cross-Section Data for Mutually Coupled Neutron-Photon Transport Calculations in the Monte Carlo N-Particle (MCNP) Radiation Transport Code

    Energy Technology Data Exchange (ETDEWEB)

    White, Morgan C. [Univ. of Florida, Gainesville, FL (United States)

    2000-07-01

    The fundamental motivation for the research presented in this dissertation was the need to development a more accurate prediction method for characterization of mixed radiation fields around medical electron accelerators (MEAs). Specifically, a model is developed for simulation of neutron and other particle production from photonuclear reactions and incorporated in the Monte Carlo N-Particle (MCNP) radiation transport code. This extension of the capability within the MCNP code provides for the more accurate assessment of the mixed radiation fields. The Nuclear Theory and Applications group of the Los Alamos National Laboratory has recently provided first-of-a-kind evaluated photonuclear data for a select group of isotopes. These data provide the reaction probabilities as functions of incident photon energy with angular and energy distribution information for all reaction products. The availability of these data is the cornerstone of the new methodology for state-of-the-art mutually coupled photon-neutron transport simulations. The dissertation includes details of the model development and implementation necessary to use the new photonuclear data within MCNP simulations. A new data format has been developed to include tabular photonuclear data. Data are processed from the Evaluated Nuclear Data Format (ENDF) to the new class ''u'' A Compact ENDF (ACE) format using a standalone processing code. MCNP modifications have been completed to enable Monte Carlo sampling of photonuclear reactions. Note that both neutron and gamma production are included in the present model. The new capability has been subjected to extensive verification and validation (V&V) testing. Verification testing has established the expected basic functionality. Two validation projects were undertaken. First, comparisons were made to benchmark data from literature. These calculations demonstrate the accuracy of the new data and transport routines to better than 25 percent. Second

  18. Oxidative Damage and Mutagenic Potency of Fast Neutron and UV-B Radiation in Pollen Mother Cells and Seed Yield of Vicia faba L.

    Directory of Open Access Journals (Sweden)

    Ekram Abdel Haliem

    2013-01-01

    Full Text Available In recent years, there has been a great deal of attention toward free radicals, reactive oxygen species (ROS generated by exposure of crop plant cells to physical radiations. Henceforth, the current study was planned to compare oxidative stress and mutagenic potential of different irradiation doses of fast neutron (FN and UV-B on meiotic-pollen mother cells (PMCs, pollen grains (PGs and seeds yielded from irradiated faba beans seedlings. On the cytogenetic level, each irradiation type had special interference with DNA of PMC and exhibited wide range of mutagenic action on the frequency and type of chromosomal anomalies, fertility of PGs and seed yield productivity based on the irradiation exposure dose and radiation sensitivity of faba bean plants compared with un-irradiated ones. On the molecular level, SDS-PAGE and RPAD-PCR analyses of seeds yielded from irradiated seedlings exhibited distinctive polymorphisms based on size, intensity, appearance, and disappearance of polypeptides bands compared with un-irradiated ones. The total values of protein and DNA polymorphisms reached 88% and 90.80% respectively. The neutron fluency (2.3 × 106 n/cm2 and UV-B dose for 1 hr were recorded as bio-positive effects. The present study proved that genetic variations revealed by cytogenetic test could be supported by gene expression (alterations in RAPD and protein profiles.

  19. Radiation doses from radiation sources of neutrons and photons by different computer calculation; Tecniche di calcolo di intensita` di dose da sorgenti di radiazione neutronica e fotonica con l`uso di codici basati su metodologie diverse

    Energy Technology Data Exchange (ETDEWEB)

    Siciliano, F.; Lippolis, G.; Bruno, S.G. [ENEA, Centro Ricerche Trisaia, Rotondella (Italy)

    1995-11-01

    In the present paper the calculation technique aspects of dose rate from neutron and photon radiation sources are covered with reference both to the basic theoretical modeling of the MERCURE-4, XSDRNPM-S and MCNP-3A codes and from practical point of view performing safety analyses of irradiation risk of two transportation casks. The input data set of these calculations -regarding the CEN 10/200 HLW container and dry PWR spent fuel assemblies shipping cask- is frequently commented as for as connecting points of input data and understanding theoretic background are concerned.

  20. The development of a high count rate neutron flux monitoring channel using silicon carbide semiconductor radiation detectors

    Science.gov (United States)

    Reisi Fard, Mehdi

    In this dissertation, a fast neutron flux-monitoring channel, which is based on the use of SiC semiconductor detectors is designed, modeled and experimentally evaluated as a power monitor for the Gas Turbine Modular Helium Reactors. A detailed mathematical model of the SiC diode detector and the electronic processing channel is developed using TRIM, MATLAB and PSpice simulation codes. The flux monitoring channel is tested at the OSU Research Reactor. The response of the SiC neutron-monitoring channel to neutrons is in close agreement to simulation results. Linearity of the channel response to thermal and fast neutron fluxes, pulse height spectrum of the channel, energy calibration of the channel and the detector degradation in a fast neutron flux are presented. Along with the model of the neutron monitoring channel, a Simulink model of the GT-MHR core has been developed to evaluate the power monitoring requirements for the GT-MHR that are most demanding for the SiC diode power monitoring system. The Simulink model is validated against a RELAP5 model of the GT-MHR. This dyanamic model is used to simulate reactor transients at the full power and at the start up, in order to identify the response time requirements of the GT-MHR. Based on the response time requirements that have been identified by the Simulink model and properties of the monitoring channel, several locations in the central reflector and the reactor cavity are identified to place the detector. The detector lifetime and dynamic range of the monitoring channel at the detector locations are calculated. The channel dynamic range in the GT-MHR central reflector covers four decades of the reactor power. However, the detector does not survive for a reactor refueling cycle in the central reflector. In the reactor cavity, the detector operates sufficiently long; however, the dynamic range of the channel is smaller than the dynamic range of the channel in the central reflector.

  1. Probabilistic Analysis of Crack Width

    Directory of Open Access Journals (Sweden)

    J. Marková

    2000-01-01

    Full Text Available Probabilistic analysis of crack width of a reinforced concrete element is based on the formulas accepted in Eurocode 2 and European Model Code 90. Obtained values of reliability index b seem to be satisfactory for the reinforced concrete slab that fulfils requirements for the crack width specified in Eurocode 2. However, the reliability of the slab seems to be insufficient when the European Model Code 90 is considered; reliability index is less than recommended value 1.5 for serviceability limit states indicated in Eurocode 1. Analysis of sensitivity factors of basic variables enables to find out variables significantly affecting the total crack width.

  2. A deterministic width function model

    Directory of Open Access Journals (Sweden)

    C. E. Puente

    2003-01-01

    Full Text Available Use of a deterministic fractal-multifractal (FM geometric method to model width functions of natural river networks, as derived distributions of simple multifractal measures via fractal interpolating functions, is reported. It is first demonstrated that the FM procedure may be used to simulate natural width functions, preserving their most relevant features like their overall shape and texture and their observed power-law scaling on their power spectra. It is then shown, via two natural river networks (Racoon and Brushy creeks in the United States, that the FM approach may also be used to closely approximate existing width functions.

  3. Energetic neutron and gamma-ray spectra under the earth radiation belts according to "SALYUT-7" [correction of "SALUTE-7"]-"KOSMOS-1686" orbital complex and "CORONAS-I" satellite data.

    Science.gov (United States)

    Bogomolov, A V; Dmitriev, A V; Myagkova, I N; Ryumin, S P; Smirnova, O N; Sobolevsky, I M

    1998-01-01

    The spectra of neutrons >10 MeV and gamma-rays 1.5-100 MeV under the Earth Radiation Belts, restored from the data, obtained onboard orbital complex "SALYUT-7" [correction of "SALUTE-7"]-"KOSMOS-1686", are presented. The spectra shapes are similar to those for albedo neutrons and gamma-rays, but absolute values of their fluxes (0.2 cm-2 s-1 for neutrons, 0.8 cm-2 s-1 for gamma-rays at the equator and 1.2 cm-2 s-1, 1.9 cm-2 s-1, accordingly, at L=1.9) are several times as large. It is possibly explained by the fact that most of the detected particles were produced by the cosmic ray interactions with the orbital complex matter. Neutron and gamma-ray fluxes obtained from "CORONAS-1" data are near those for albedo particles.

  4. Dosimetric evaluation of spectrophotometric response of alanine gel solution for gamma, photons, electrons and thermal neutrons radiations; Avaliacao dosimetrica da resposta espectrofotometrica da solucao gel de alanina para radiacao gama, de fotons, de eletrons e de neutrons termicos

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Cleber Feijo

    2009-07-01

    Alanine Gel Dosimeter is a new gel material developed at IPEN that presents significant improvement on Alanine system developed by Costa. The DL-Alanine (C{sub 3}H{sub 7}NO{sub 2}) is an amino acid tissue equivalent that improves the production of ferric ions in the solution. This work aims to analyse the main dosimetric characteristics this new gel material for future application to measure dose distribution. The performance of Alanine gel solution was evaluated to gamma, photons, electrons and thermal neutrons radiations using the spectrophotometry technique. According to the obtained results for the different studied radiation types, the reproducibility intra-batches and inter-batches is better than 4% and 5%, respectively. The dose response presents a linear behavior in the studied dose range. The response dependence as a function of dose rate and incident energy is better 2% and 3%, respectively. The lower detectable dose is 0.1 Gy. The obtained results indicate that the Alanine gel dosimeter presents good performance and can be useful as an alternative dosimeter in the radiotherapy area, using MRI technique for tridimensional dose distribution evaluation. (author)

  5. Neutron/muon correlation functions to improve neutron detection capabilities outside nuclear facilities

    Science.gov (United States)

    Ordinario, Donald Thomas

    The natural neutron background rate is largely due to cosmic ray interactions in the atmosphere and the subsequent neutron emission from the interaction products. The neutron background is part of a larger cosmic radiation shower that also includes electrons, gamma rays, and muons. Since neutrons interact much differently than muons in building materials, the muon and neutron fluence rates in the natural background can be compared to the measured muon and neutron fluence rate when shielded by common building materials. The simultaneous measurement of muon and neutron fluence rates might allow for an earlier identification of man-made neutron sources, such as hidden nuclear materials. This study compares natural background neutron rates to computer simulated neutron rates shielded by common structural and building materials. The characteristic differences between neutrons and muons resulted in different attenuation properties under the same shielded conditions. Correlation functions between cosmic ray generated neutrons and muons are then used to predict neutron fluence rates in different urban environments.

  6. Isomeric ratio measurements for the radiative neutron capture 176Lu(n ,γ ) at the LANL DANCE facility

    Science.gov (United States)

    Denis-Petit, D.; Roig, O.; Méot, V.; Morillon, B.; Romain, P.; Jandel, M.; Kawano, T.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Keksis, A. L.; Rundberg, R. S.; Ullmann, J. L.

    2016-11-01

    The isomeric ratios for the neutron capture reaction 176Lu(n ,γ ) to the Jπ=5 /2- , 761.7 keV, T1 /2=32.8 ns and the Jπ=15 /2+ , 1356.9 keV, T1 /2=11.1 ns levels of 177Lu have been measured for the first time. The experiment was carried out with the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos National Laboratory. Measured isomeric ratios are compared with talys calculations using different models for photon strength functions, level densities, and optical potentials. In order to reproduce the experimental γ -ray spectra, a low-energy resonance must be added in the photon strength function used in our Hauser-Feshbach calculations.

  7. Energetic Constraints on the Width of the Intertropical Convergence Zone

    OpenAIRE

    2016-01-01

    The intertropical convergence zone (ITCZ) has been the focus of considerable research in recent years, with much of this work concerned with how the latitude of maximum tropical precipitation responds to natural climate variability and to radiative forcing. The width of the ITCZ, however, has received little attention despite its importance for regional climate and for understanding the general circulation of the atmosphere. This paper investigates the ITCZ width in simulations with an ideali...

  8. Grain boundary segregation in neutron-irradiated 304 stainless steel studied by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Toyama, T., E-mail: ttoyama@imr.tohoku.ac.jp [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nozawa, Y. [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Van Renterghem, W. [SCK Bullet CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol (Belgium); Matsukawa, Y.; Hatakeyama, M.; Nagai, Y. [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Al Mazouzi, A. [EDF R and D, Avenue des Renardieres Ecuelles, 77818 Moret sur Loing Cedex (France); Van Dyck, S. [SCK Bullet CEN, Nuclear Materials Science Institute, Boeretang 200, 2400 Mol (Belgium)

    2012-06-15

    Radiation-induced segregation (RIS) of solute atoms at a grain boundary (GB) in 304 stainless steel (SS), neutron-irradiated to a dose of 24 dpa at 300 Degree-Sign C in the fuel wrapper plates of a commercial pressurized water reactor, was investigated using laser-assisted atom probe tomography (APT). Ni, Si, and P enrichment and Cr and Fe depletion at the GB were evident. The full-width at half-maximum of the RIS region was {approx}3 nm for the concentration profile peaks of Ni and Si. The atomic percentages of Ni, Si, and Cr at the GB were {approx}19%, {approx}7%, and {approx}14%, respectively, in agreement with previously-reported values for neutron-irradiated SS. A high number density of intra-granular Ni-Si rich precipitates formed in the matrix. A precipitate-denuded zone with a width of {approx}10 nm appeared on both sides of the GB.

  9. Resonance neutron capture in {sup 60}Ni below 450 keV

    Energy Technology Data Exchange (ETDEWEB)

    Corvi, F.; Fioni, G. E-mail: gfioni@cea.fr; Gunsing, F.; Mutti, P.; Zanini, L

    2002-01-28

    High-resolution neutron capture cross-section measurements on {sup 60}Ni have been performed at the Geel Linear Accelerator in the energy range from 1 to 450 keV. An experimentally determined weighting function, obtained by a total energy detection set-up, has been applied to the measured capture spectra. The parameters of 275 resonances have been determined in a recent reanalysis using the FANAC R-matrix shape fitting code. Accurate values of the maxwellian-averaged capture cross section for stellar temperatures ranging from kT=5 to 100 keV, corresponding to different scenarios of s-process stellar nucleosynthesis, have been calculated. The distributions of partial radiative widths for s- and p-wave resonances have been derived. A correlation of 0.64 between capture and reduced neutron widths is compatible with the presence of nonstatistical effects in the capture of {sup 60}Ni.

  10. Resonance neutron capture in sup 6 sup 0 Ni below 450 keV

    CERN Document Server

    Corvi, F; Gunsing, F; Mutti, P; Zanini, L

    2002-01-01

    High-resolution neutron capture cross-section measurements on sup 6 sup 0 Ni have been performed at the Geel Linear Accelerator in the energy range from 1 to 450 keV. An experimentally determined weighting function, obtained by a total energy detection set-up, has been applied to the measured capture spectra. The parameters of 275 resonances have been determined in a recent reanalysis using the FANAC R-matrix shape fitting code. Accurate values of the maxwellian-averaged capture cross section for stellar temperatures ranging from kT=5 to 100 keV, corresponding to different scenarios of s-process stellar nucleosynthesis, have been calculated. The distributions of partial radiative widths for s- and p-wave resonances have been derived. A correlation of 0.64 between capture and reduced neutron widths is compatible with the presence of nonstatistical effects in the capture of sup 6 sup 0 Ni.

  11. Measurements of photon and neutron leakage from medical linear accelerators and Monte Carlo simulation of tenth value layers of concrete used for intensity modulated radiation therapy treatment

    Science.gov (United States)

    Jaradat, Adnan Khalaf

    The x ray leakage from the housing of a therapy x ray source is regulated to be bubble detector of type BD-PND and using Track-Etch detectors. The highest neutron dose equivalent per unit electron dose was at 0° for all electron energies. The neutron leakage from photon beams was the highest between all the machines. Intensity modulated radiation therapy (IMRT) delivery consists of a summation of small beamlets having different weights that make up each field. A linear accelerator room designed exclusively for IMRT use would require different, probably lower, tenth value layers (TVL) for determining the required wall thicknesses for the primary barriers. The first, second, and third TVL of 60Co gamma rays and photons from 4, 6, 10, 15, and 18 MV x ray beams by concrete have been determined and modeled using a Monte Carlo technique (MCNP version 4C2) for cone beams of half-opening angles of 0°, 3°, 6°, 9°, 12°, and 14°.

  12. Other applications of neutron beams in material sciences; Autres utilisations des faisceaux de neutrons en science des materiaux

    Energy Technology Data Exchange (ETDEWEB)

    Novion, C.H. de

    1997-12-31

    The various applications of neutron beams are reviewed. The different mechanisms involved in neutron interaction with matter are explained. We notice that generally neutron radiation effects are unfavorable but can be turned into efficient tools to add new structures or properties to materials, silicon doping is an example. The basis principles of neutron activation analysis and neutron radiography are described. (A.C.)

  13. Correlation between interalar width and intercommisural width against mesiodistal width of central upper incisor in Buginese tribe

    Directory of Open Access Journals (Sweden)

    Bahruddin Thalib

    2016-04-01

    Full Text Available Various types of anatomical landmarks of the face should match its proportions with the size of the teeth which is the interalar width, intercomissural width, interpupillary width, Intercanthal width, and byzigomatic width. Some of face landmarks can be used as a guide in the selection of anterior teeth in complete denture, especially if the pre extraction record such as radiography image, extracted teeth, model study, the remaining teeth, face shape, and the shape of the curved jaw have been lost. The objective of this study was to evaluate the correlation between interalar width and intercommisural width against mesiodistal incisivus centralis width in a group of Buginese tribe. Ninety nine Buginese tribe subjects aged 17-25 were selected. The interalar width, intercommisural width, and mesiodistal incisor centralis teeth were measured using caliper about three times for accuracy and precision. Mean of interalar width and mesiodistal incisor centralis maxilla width in males more width than females (p0.05. The degree of correlation between interalar width against mesiodistal incisor centralis maxilla width was 0.030, -0.246, 0,225 in Buginese tribe, males, and females (p>0.05. : The degree of correlation between intercommisural width against  mesiodistal incisor centralis maxilla width in Buginese tribe was 0,054, 0,013, 0,153 in Buginese tribe, males, and females (p>0.05. The degree of correlation between interalar width and intercommisural width was 0.301 and 0.356 in Buginese tribe and males (p0.05. In conclusion, there is no significant correlation between interalar width and intercommisural width against mesiodistal incisor centralis maxilla width in a group of Buginese tribe. Interalar width and intercommisural width  directly proportional to mesiodistal incisor centralis maxilla in a group of Buginese tribe. Interalar width and intercommisural width  inversely proportional to mesiodistal incisor centralis maxilla in males and directly

  14. Why curvature radiation in neutron-star magnetospheres should be treated in the framework of quantum electrodynamics

    Science.gov (United States)

    Voisin, G.; Bonazzola, S.; Mottez, F.

    2016-12-01

    Curvature radiation is a key phenomenon in pulsar and magnetar magnetospheres. It is classically conceptually very close to synchrotron radiation, however we will show that in ultra-relativistic very-high-magnetic-field environments, the same approximations that lead to its use are also leading quickly to a potential quantized regime where the classical theory may fail. We explain in some details these caveats and give an outline of a quantum-electrodynamics treatment. We show that the internal consistency of the theory of curvature radiation is improved, and some interesting effects due to spin-flip transitions may occur.

  15. Biological width: No violation zone

    Directory of Open Access Journals (Sweden)

    Ashu Sharma

    2012-01-01

    Full Text Available Maintenance of gingival health is one of the keys for the longevity of teeth, as well as for the longevity of restorations. The concept of Biologic width has been widely described by periodontists and restorative dentists. An adequate understanding of relationship between periodontal tissues and restorative dentistry is paramount to ensure adequate form, function and esthetics, and comfort of the dentition. While most clinicians are aware of this important relationship, uncertainty remains regarding specific concepts such as biologic width and indications and applications of surgical crown lengthening. These violations lead to complications like gingival inflammation, alveolar bone loss and improper fit of the restorative component. This review gives the wide aspect of the complex question of biologic width and represents an attempt to answer some of the demands in relation to it. The article also discusses the possible methods to assess biologic width, problems that occur after improper margin placement in the periodontium and the alternative procedures for prevention of biological width violation.

  16. Neutrons-disturbance resisting capacity evaluation for inorganic scintillator by steady radiation source-current method%稳态辐射源电流法评估无机闪烁体抗中子干扰能力

    Institute of Scientific and Technical Information of China (English)

    胡孟春; 冯璟华; 周刚; 李忠宝; 唐登攀; 张建华; 司粉妮; 黄雁

    2012-01-01

    n、γ混合场中测量γ辐射时,通常要应用无机闪烁体构成探测器,探测器抗中子干扰能力是判断测量信号质量的重要依据之一.无机闪烁体的γ绝对灵敏度是可以比较精确标定的,而无机闪烁体的中子绝对灵敏度是很难精确标定的,本文介绍稳态辐射源电流标定法,在不用测量测点注量率的情况下,也能够初步评估出无机闪烁体的抗中子干扰能力.%When measuring γ radiation in the neutron-gamma mixed field with inorganic scintillator as detector, the capacity of resisting neutrons-disturbance of the detector is an important basis for judging the quality of the signal. The γ absolute sensitivity of the inorganic scintillator can be calibrated accurately, but the neutron absolute sensitivity is very hard to be calibrated accurately. On the basis of this fact, this paper introduced the steady radiation source-current method and with which, the capacity of resisting neutrons-disturbance for inorganic scintillator can be evaluated without the measurement of neutron fluence rate.

  17. Response to the comment by N. Severijns, O. Zimmer, H.-F. Wirth and D. Rich regarding article "Observation of the neutron radiative decay" in JETP Letters 83(1) p.5

    CERN Document Server

    Khafizov, R U

    2006-01-01

    We wouldn't like to bring up discrimination, but the tone of the commentary, which does not contain any science-based criticism or any alternative suggestions, does make one think of an unduly disrespectful attitude both towards the Russian participants and the project on radiative neutron decay itself. Here we cite our response to the commentary of our Western collaborants to the article printed in JETP Letters 83(1) p.5. We remain firm in the positions published in this article. In our last experiment we measured the relative intensity of radiative neutron decay (B.R.=(3.2+-1.6) 10-3 with C.L.=99.7% and lower energy limit of radiative gamma-quanta measured equal to 35 KeV) .

  18. Radiation Protection

    Energy Technology Data Exchange (ETDEWEB)

    Loos, M

    2001-04-01

    Major achievements of SCK-CEN's Radiation Protection Department in 2000 are described. The main areas for R and D of the department remain neutron dosimetry and neutron activation analysis, safeguards information handling and non-destructive assay techniques. Further activities include low-level radioactivity measurements in environmental and biological samples and radiation protection research. Finally, achievements in decision strategy research and social sciences in nuclear research are reported.

  19. Measurements of Neutron Energy Spectra and Neutron Dose Equivalent Rates of Workplaces in TQNPC-Ⅲ

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Monitoring for neutron doses is one of the important activities for radiation protection. And the information about neutron energy distributions of the measured fields is necessary for the correct

  20. CD(4) has bounded width

    CERN Document Server

    Carvalho, Catarina; Marković, Petar; Maróti, Miklós

    2007-01-01

    We prove that the constraint languages invariant under a short sequence of J\\'onsson terms (containing at most three non-trivial ternary terms) are tractable by showing that they have bounded width. This improves the previous result by Kiss and Valeriote and presents some evidence that the Larose-Zadori conjecture holds in the congruence-distributive case.

  1. Maximum proton kinetic energy and patient-generated neutron fluence considerations in proton beam arc delivery radiation therapy.

    Science.gov (United States)

    Sengbusch, E; Pérez-Andújar, A; DeLuca, P M; Mackie, T R

    2009-02-01

    Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy of protons, immediately prior to entry into the patient, that must be reached by the treatment system. The commonly used value for the maximum kinetic energy required for a medical proton accelerator is 250 MeV, but it has not been demonstrated that this energy is indeed necessary to treat all or most patients eligible for proton therapy. This article quantifies the maximum kinetic energy of protons, immediately prior to entry into the patient, necessary to treat a given percentage of patients with rotational proton therapy, and examines the impact of this energy threshold on the cost and feasibility of a compact, gantry-mounted proton accelerator treatment system. One hundred randomized treatment plans from patients treated with IMRT were analyzed. The maximum radiological pathlength from the surface of the patient to the distal edge of the treatment volume was obtained for 180 degrees continuous arc proton therapy and for 180 degrees split arc proton therapy (two 90 degrees arcs) using CT# profiles from the Pinnacle (Philips Medical Systems, Madison, WI) treatment planning system. In each case, the maximum kinetic energy of protons, immediately prior to entry into the patient, that would be necessary to treat the patient was calculated using proton range tables for various media. In addition, Monte Carlo simulations were performed to quantify neutron production in a water phantom representing a patient as a function of the maximum proton kinetic energy achievable by a proton treatment system. Protons with a kinetic energy of 240 MeV, immediately prior to entry into the patient, were needed to treat 100% of patients in this study. However, it was shown that 90% of patients could be treated at 198 MeV, and 95% of patients could be treated at 207 MeV. Decreasing the

  2. Quinolone and Glycopeptide Therapy for Infection in Mouse Following Exposure to Mixed-Field Neutron-Gamma-Photon Radiation

    Science.gov (United States)

    1993-01-01

    Brook and Ledney 1990, 1991, [nI(n+7y=0ś] radiation. The mortality rate of mice and Brook et al. 1990) demonstrated the ability of quino - recovery of...failed to Streptococcus spp., reduced the infection due to quino - prevent Gram-positive coccal infection, due to the development of glycopeptide

  3. γ-H2AX responds to DNA damage induced by long-term exposure to combined low-dose-rate neutron and γ-ray radiation.

    Science.gov (United States)

    Zhang, Junlin; He, Ying; Shen, Xianrong; Jiang, Dingwen; Wang, Qingrong; Liu, Qiong; Fang, Wen

    2016-01-01

    Risk estimates for low-dose radiation (LDR) remain controversial. The possible involvement of DNA repair-related genes in long-term low-dose-rate neutron-gamma radiation exposure is poorly understood. In this study, 60 rats were divided into control groups and irradiated groups, which were exposed to low-dose-rate n-γ combined radiation (LDCR) for 15, 30, or 60 days. The effects of different cumulative radiation doses on peripheral blood cell (PBC), subsets of T cells of peripheral blood lymphocytes (PBL) and DNA damage repair were investigated. Real-time PCR and immunoblot analyses were used to detect expression of DNA DSB-repair-related genes involved in the NHEJ pathway, such as Ku70 and Ku80, in PBL. The mRNA level of H2AX and the expression level of γ-H2AX were detected by real-time PCR, immunoblot, and flow cytometry. White blood cells (WBC) and platelets (PLT) of all ionizing radiation (IR) groups decreased significantly, while no difference was seen between the 30 day and 60 day exposure groups. The numbers of CD3(+), CD4(+) T cells and CD4(+)/CD8(+) in the PBL of IR groups were lower than in the control group. In the 30 day and 60 day exposure groups, CD8(+) T cells decreased significantly. Real-time PCR and immunoblot results showed no significant difference in the mRNA and protein expression of Ku70 and Ku80 between the control groups and IR groups. However, the mRNA of H2AX increased significantly, and there was a positive correlation with dose. There was no difference in the protein expression of γ-H2AX between 30 day and 60 day groups, which may help to explain the damage to PBL. In conclusion, PBL damage increased with cumulative dose, suggesting that γ-H2AX, but neither Ku70 nor Ku80, plays an important role in PBL impairment induced by LDCR. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  4. The perturbation of backscattered fast neutrons spectrum caused by the resonances of C, N and O for possible use in pyromaterial detection

    Science.gov (United States)

    Abedin, Ahmad Firdaus Zainal; Ibrahim, Noorddin; Zabidi, Noriza Ahmad; Abdullah, Abqari Luthfi Albert

    2015-04-01

    Neutron radiation is able to determine the signature of land mine detection based on backscattering energy spectrum of landmine. In this study, the Monte Carlo simulation of backscattered fast neutrons was performed on four basic elements of land mine; hydrogen, nitrogen, oxygen and carbon. The moderation of fast neutrons to thermal neutrons and their resonances cross-section between 0.01 eV until 14 MeV were analysed. The neutrons energies were divided into 29 groups and ten million neutrons particles histories were used. The geometries consist of four main components: neutrons source, detectors, landmine and soil. The neutrons source was placed at the origin coordinate and shielded with carbon and polyethylene. Americium/Beryllium neutron source was placed inside lead casing of 1 cm thick and 2.5 cm height. Polyethylene was used to absorb and disperse radiation and was placed outside the lead shield of width 10 cm and height 7 cm. Two detectors were placed between source with distance of 8 cm and radius of 1.9 cm. Detectors of Helium-3 was used for neutron detection as it has high absorption cross section for thermal neutrons. For the anomaly, the physical is in cylinder form with radius of 10 cm and 8.9 cm height. The anomaly is buried 5 cm deep in the bed soil measured 80 cm radius and 53.5 cm height. The results show that the energy spectrum for the four basic elements of landmine with specific pattern which can be used as indication for the presence of landmines.

  5. The perturbation of backscattered fast neutrons spectrum caused by the resonances of C, N and O for possible use in pyromaterial detection

    Energy Technology Data Exchange (ETDEWEB)

    Abedin, Ahmad Firdaus Zainal, E-mail: firdaus087@gmail.com; Ibrahim, Noorddin; Zabidi, Noriza Ahmad; Abdullah, Abqari Luthfi Albert [Department of Defence Science, Universiti Pertahanan Nasional Malaysia, Kem Sungai Besi, Kuala Lumpur 57000 (Malaysia)

    2015-04-29

    Neutron radiation is able to determine the signature of land mine detection based on backscattering energy spectrum of landmine. In this study, the Monte Carlo simulation of backscattered fast neutrons was performed on four basic elements of land mine; hydrogen, nitrogen, oxygen and carbon. The moderation of fast neutrons to thermal neutrons and their resonances cross-section between 0.01 eV until 14 MeV were analysed. The neutrons energies were divided into 29 groups and ten million neutrons particles histories were used. The geometries consist of four main components: neutrons source, detectors, landmine and soil. The neutrons source was placed at the origin coordinate and shielded with carbon and polyethylene. Americium/Beryllium neutron source was placed inside lead casing of 1 cm thick and 2.5 cm height. Polyethylene was used to absorb and disperse radiation and was placed outside the lead shield of width 10 cm and height 7 cm. Two detectors were placed between source with distance of 8 cm and radius of 1.9 cm. Detectors of Helium-3 was used for neutron detection as it has high absorption cross section for thermal neutrons. For the anomaly, the physical is in cylinder form with radius of 10 cm and 8.9 cm height. The anomaly is buried 5 cm deep in the bed soil measured 80 cm radius and 53.5 cm height. The results show that the energy spectrum for the four basic elements of landmine with specific pattern which can be used as indication for the presence of landmines.

  6. Calibration of a TLD system to estimate personal doses in fields of gamma-neutrons radiation; Calibracion de un sistema TLD para estimar dosis personal en campos de radiacion gamma-neutrones

    Energy Technology Data Exchange (ETDEWEB)

    Villegas, E.N.; Somarriba, S.I., E-mail: evillegas@unan.edu.ni [Lab. de Fisica de Radiaciones y Metrologia, Universidad Nacional Autonoma de Nicaragua (Nicaragua)

    2016-07-01

    Currently Nicaragua has no personal neutron dosimetry system. The calibration of a batch of albedo neutron dosimeters consisting of two pairs of {sup 6}LiF and {sup 7}LiF (Mg, Ti) detectors was done. The dosimeter and reader sensitivities were obtained using a {sup 137}Cs source, and a neutron calibration factor was found with a {sup 241}AmBe source. Reproducibility and homogeneity tests were performed, and the detection limit of the system was determined. This calibration will allow the beginning of neutron personal monitoring in the country. (author)

  7. Hybrid Exotic Meson Decay Width

    CERN Document Server

    Cook, M S

    2005-01-01

    We present results of a decay width calculation for a hybrid exotic meson(h, JPC=1-+) in the decay channel h to pi+a1. This calculation uses quenched lattice QCD and Luescher's finite box method. Operators for the h and pi+a1 states are used in a correlation matrix which was expanded by varying the smearing and fuzzing levels at source and sink points. Scattering phase shifts for a discrete set of relative pi+a1 momenta are determined using eigenvalues of the correlation matrix and formulae derived by Luescher. The phase shift data is very sparse, but fits to a Breit-Wigner model are made, resulting in a decay width of about 80 MeV.

  8. On the maximal diphoton width

    CERN Document Server

    Salvio, Alberto; Strumia, Alessandro; Urbano, Alfredo

    2016-01-01

    Motivated by the 750 GeV diphoton excess found at LHC, we compute the maximal width into $\\gamma\\gamma$ that a neutral scalar can acquire through a loop of charged fermions or scalars as function of the maximal scale at which the theory holds, taking into account vacuum (meta)stability bounds. We show how an extra gauge symmetry can qualitatively weaken such bounds, and explore collider probes and connections with Dark Matter.

  9. Directional radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, Jonathan L.

    2017-09-12

    Directional radiation detectors and systems, methods, and computer-readable media for using directional radiation detectors to locate a radiation source are provided herein. A directional radiation detector includes a radiation sensor. A radiation attenuator partially surrounds the radiation sensor and defines an aperture through which incident radiation is received by the radiation sensor. The aperture is positioned such that when incident radiation is received directly through the aperture and by the radiation sensor, a source of the incident radiation is located within a solid angle defined by the aperture. The radiation sensor senses at least one of alpha particles, beta particles, gamma particles, or neutrons.

  10. The Effect of the Gravitational Mass on the Electromagnetic Radiation from an Oblique, Relativistically Rotating Dipole (Neutron Star)

    CERN Document Server

    AlMuhammad, Anwar S

    2002-01-01

    Relying on the magnetic dipole model of the pulsar, we use the extension of the work of Haxton-Ruffini [31] for single charges by DePaolis-Ingrosso-Qadir [32] for an obliquely rotating magnetic dipole, to incorporate the effect of the gravitational mass. So, by using the numerical and analytical solutions of the differential equation for the radiation, we construct the energy spectra for different masses of the dipole-NS. These spectra show that, in relatively low angular momentum l, the effect of the gravitational mass is very significant in suppressing the relativistic enhancement factor, which had been found [27, 28, 32], by two to three orders of magnitude, as the mass changes from 0.5 solar mass to 3 solar masses. It is an indication that most of the angular momentum of the NS is retained as rotational kinetic energy instead of being radiated as an electromagnetic energy. Also, the suppressing in radiation energy is more or less independent of the angular momentum, and the high rotational velocity. We al...

  11. Minimizing the background radiation in the new neutron time-of-flight facility at CERN FLUKA Monte Carlo simulations for the optimization of the n_TOF second experimental line

    CERN Document Server

    Bergström, Ida; Elfgren, Erik

    2013-06-11

    At the particle physics laboratory CERN in Geneva, Switzerland, the Neutron Time-of-Flight facility has recently started the construction of a second experimental line. The new neutron beam line will unavoidably induce radiation in both the experimental area and in nearby accessible areas. Computer simulations for the minimization of the background were carried out using the FLUKA Monte Carlo simulation package. The background radiation in the new experimental area needs to be kept to a minimum during measurements. This was studied with focus on the contributions from backscattering in the beam dump. The beam dump was originally designed for shielding the outside area using a block of iron covered in concrete. However, the backscattering was never studied in detail. In this thesis, the fluences (i.e. the flux integrated over time) of neutrons and photons were studied in the experimental area while the beam dump design was modified. An optimized design was obtained by stopping the fast neutrons in a high Z mat...

  12. Calculation of Cross Section of Radiative Halo-Neutron Capture by 12C at Stellar Energy with the Asymptotic Normalization Coefficient Method

    Institute of Scientific and Technical Information of China (English)

    WU Kai-Su; CHEN Yong-Shou; LIU Zu-Hua; LIN Cheng-Jian; ZHANG Huan-Qiao

    2003-01-01

    The cross section of the direct neutron capture reaction 12C(n,7)13C(l/2+) is calculated with the asymptotic normalization coefficient method. The result is in good agreement with a recent experiment at low energy. An enormous enhancement of cross section is found for this direct neutron capture in which a p-wave neutron is captured into an 2?i/2 orbit with neutron halo. The possible effect of the neutron halo structure presented in this reaction on the s-process in astrophysics is discussed in general.

  13. Improved estimate of the detectability of gravitational radiation from a magnetically confined mountain on an accreting neutron star

    CERN Document Server

    Vigelius, M

    2009-01-01

    We give an improved estimate of the detectability of gravitational waves from magnetically confined mountains on accreting neutron stars. The improved estimate includes the following effects for the first time: three-dimensional hydromagnetic ("fast") relaxation, three-dimensional resistive ("slow") relaxation, realistic accreted masses $M_a \\la 2 \\times 10^{-3} M_\\odot$, (where the mountain is grown ab initio by injection), and verification of the curvature rescaling transformation employed in previous work. Typically, a mountain does not relax appreciably over the lifetime of a low-mass X-ray binary. The ellipticity reaches $\\epsilon \\approx 2 \\times 10^{-5}$ for $M_a=2\\times 10^{-3} M_\\odot$. The gravitational wave spectrum for triaxial equilibria contains an additional line, which, although weak, provides valuable information about the mountain shape. We evaluate the detectability of magnetic mountains with Initial and Advanced LIGO. For a standard, coherent matched filter search, we find a signal-to-nois...

  14. Probing astrophysically important states in $^{26}$Mg nucleus to study neutron sources for the $s$-Process

    CERN Document Server

    Talwar, R; Berg, G P A; Bin, L; Bisterzo, S; Couder, M; deBoer, R J; Fang, X; Fujita, H; Fujita, Y; Gorres, J; Hatanaka, K; Itoh, T; Kadoya, T; Long, A; Miki, K; Patel, D; Pignatari, M; Shimbara, Y; Tamii, A; Wiescher, M; Yamamoto, T; Yosoi, M

    2015-01-01

    The $^{22}$Ne($\\alpha$,n)$^{25}$Mg reaction is the dominant neutron source for the slow neutron capture process ($s$-process) in massive stars and contributes, together with the $^{13}$C($\\alpha$,n)$^{16}$O, to the production of neutrons for the $s$-process in Asymptotic Giant Branch (AGB) stars. However, the reaction is endothermic and competes directly with the $^{22}$Ne($\\alpha,\\gamma)^{26}$Mg radiative capture. The uncertainties for both reactions are large owing to the uncertainty in the level structure of $^{26}$Mg near the alpha and neutron separation energies. These uncertainties are affecting the s-process nucleosynthesis calculations in theoretical stellar models. Indirect studies in the past have been successful in determining the energies, $\\gamma$-ray and neutron widths of the $^{26}$Mg states in the energy region of interest. But, the high Coulomb barrier hinders a direct measurement of the resonance strengths, which are determined by the $\\alpha$-widths for these states. The goal of the present...

  15. Human circulating plasma DNA significantly decreases while lymphocyte DNA damage increases under chronic occupational exposure to low-dose gamma-neutron and tritium β-radiation

    Energy Technology Data Exchange (ETDEWEB)

    Korzeneva, Inna B., E-mail: inna.korzeneva@molgen.vniief.ru [Russian Federal Nuclear Center – All-Russian Research Institute of Experimental Physics (RFNC-VNIIEF) 607190, Sarov, 37 Mira ave., Nizhniy Novgorod Region (Russian Federation); Kostuyk, Svetlana V.; Ershova, Liza S. [Research Centre for Medical Genetics, Russian Academy of Medical Sciences, 115478 Moscow, 1 Moskvorechye str. (Russian Federation); Osipov, Andrian N. [Federal Medial and Biological Center named after Burnazyan of the Federal Medical and Biological Agency (FMBTz named after Burnazyan of FMBA), Moscow (Russian Federation); State Research Center - Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency, Zhivopisnaya, 46, Moscow, 123098 (Russian Federation); Zhuravleva, Veronika F.; Pankratova, Galina V. [Russian Federal Nuclear Center – All-Russian Research Institute of Experimental Physics (RFNC-VNIIEF) 607190, Sarov, 37 Mira ave., Nizhniy Novgorod Region (Russian Federation); Porokhovnik, Lev N.; Veiko, Natalia N. [Research Centre for Medical Genetics, Russian Academy of Medical Sciences, 115478 Moscow, 1 Moskvorechye str. (Russian Federation)

    2015-09-15

    Highlights: • The chronic exposure to low-dose IR induces DSBs in human lymphocytes (TM index). • Exposure to IR decreases the level of human circulating DNA (cfDNA index). • IR induces an increase of DNase1 activity (DNase1 index) in plasma. • IR induces an increase of the level of antibodies to DNA (Ab DNA index) in plasma. • The ratio cfDNA/(DNase 1 × Ab DNA × TM) is a potential marker of human exposure to IR. - Abstract: The blood plasma of healthy people contains cell-fee (circulating) DNA (cfDNA). Apoptotic cells are the main source of the cfDNA. The cfDNA concentration increases in case of the organism’s cell death rate increase, for example in case of exposure to high-dose ionizing radiation (IR). The objects of the present research are the blood plasma and blood lymphocytes of people, who contacted occupationally with the sources of external gamma/neutron radiation or internal β-radiation of tritium N = 176). As the controls (references), blood samples of people, who had never been occupationally subjected to the IR sources, were used (N = 109). With respect to the plasma samples of each donor there were defined: the cfDNA concentration (the cfDNA index), DNase1 activity (the DNase1 index) and titre of antibodies to DNA (the Ab DNA index). The general DNA damage in the cells was defined (using the Comet assay, the tail moment (TM) index). A chronic effect of the low-dose ionizing radiation on a human being is accompanied by the enhancement of the DNA damage in lymphocytes along with a considerable cfDNA content reduction, while the DNase1 content and concentration of antibodies to DNA (Ab DNA) increase. All the aforementioned changes were also observed in people, who had not worked with the IR sources for more than a year. The ratio cfDNA/(DNase1 × Ab DNA × TM) is proposed to be used as a marker of the chronic exposure of a person to the external low-dose IR. It was formulated the assumption that the joint analysis of the cfDNA, DNase1, Ab

  16. Human circulating plasma DNA significantly decreases while lymphocyte DNA damage increases under chronic occupational exposure to low-dose gamma-neutron and tritium β-radiation.

    Science.gov (United States)

    Korzeneva, Inna B; Kostuyk, Svetlana V; Ershova, Liza S; Osipov, Andrian N; Zhuravleva, Veronika F; Pankratova, Galina V; Porokhovnik, Lev N; Veiko, Natalia N

    2015-09-01

    The blood plasma of healthy people contains cell-fee (circulating) DNA (cfDNA). Apoptotic cells are the main source of the cfDNA. The cfDNA concentration increases in case of the organism's cell death rate increase, for example in case of exposure to high-dose ionizing radiation (IR). The objects of the present research are the blood plasma and blood lymphocytes of people, who contacted occupationally with the sources of external gamma/neutron radiation or internal β-radiation of tritium N = 176). As the controls (references), blood samples of people, who had never been occupationally subjected to the IR sources, were used (N = 109). With respect to the plasma samples of each donor there were defined: the cfDNA concentration (the cfDNA index), DNase1 activity (the DNase1 index) and titre of antibodies to DNA (the Ab DNA index). The general DNA damage in the cells was defined (using the Comet assay, the tail moment (TM) index). A chronic effect of the low-dose ionizing radiation on a human being is accompanied by the enhancement of the DNA damage in lymphocytes along with a considerable cfDNA content reduction, while the DNase1 content and concentration of antibodies to DNA (Ab DNA) increase. All the aforementioned changes were also observed in people, who had not worked with the IR sources for more than a year. The ratio cfDNA/(DNase1×Ab DNA × TM) is proposed to be used as a marker of the chronic exposure of a person to the external low-dose IR. It was formulated the assumption that the joint analysis of the cfDNA, DNase1, Ab DNA and TM values may provide the information about the human organism's cell resistivity to chronic exposure to the low-dose IR and about the development of the adaptive response in the organism that is aimed, firstly, at the effective cfDNA elimination from the blood circulation, and, secondly - at survival of the cells, including the cells with the damaged DNA. Copyright © 2015. Published by Elsevier B.V.

  17. The Electromagnetic Spectrum of Neutron Stars

    CERN Document Server

    Baykal, Altan; Inam, Sitki C; Grebenev, Sergei

    2005-01-01

    Neutron stars hold a central place in astrophysics, not only because they are made up of the most extreme states of the condensed matter, but also because they are, along with white dwarfs and black holes, one of the stable configurations that stars reach at the end of stellar evolution. Neutron stars posses the highest rotation rates and strongest magnetic fields among all stars. They radiate prolifically, in high energy electromagnetic radiation and in the radio band. This book is devoted to the selected lectures presented in the 6th NATO-ASI series entitled "The Electromagnetic Spectrum of Neutron Stars" in Marmaris, Turkey, on 7-18 June 2004. This ASI is devoted to the spectral properties of neutron stars. Spectral observations of neutron stars help us to understand the magnetospheric emission processes of isolated radio pulsars and the emission processes of accreting neutron stars. This volume includes spectral information from the neutron stars in broadest sense, namely neutrino and gravitational radiat...

  18. Masses, widths, and leptonic widths of the higher upsilon resonances

    Energy Technology Data Exchange (ETDEWEB)

    Lovelock, D.M.J.; Horstkotte, J.E.; Klopfenstein, C.; Lee-Franzini, J.; Romero, L.; Schamberger, R.D.; Youssef, S.; Franzini, P.; Son, D.; Tuts, P.M.

    1985-02-04

    The masses, total widths, and leptonic widths of three triplet s-wave bb-bar states UPSILON(4S), UPSILON(5S), and UPSILON(6S) are determined from measurements of the e/sup +/e/sup -/ annihilation cross section into hadrons for 10.55

  19. Neutron Beams from Deuteron Breakup at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    McMahan, M.A.; Ahle, L.; Bleuel, D.L.; Bernstein, L.; Braquest, B.R.; Cerny, J.; Heilbronn, L.H.; Jewett, C.C.; Thompson, I.; Wilson, B.

    2007-07-31

    Accelerator-based neutron sources offer many advantages, in particular tunability of the neutron beam in energy and width to match the needs of the application. Using a recently constructed neutron beam line at the 88-Inch Cyclotron at LBNL, tunable high-intensity sources of quasi-monoenergetic and broad spectrum neutrons from deuteron breakup are under development for a variety of applications.

  20. Neutron induced degradation in nitrided pyrogenic field oxide MOS capacitors

    CERN Document Server

    Vaidya, S J; Shaikh, A M; Chandorkar, A N

    2002-01-01

    Neutron induced oxide charge trapping and generation of interface states in MOS capacitors with pyrogenic and nitrided pyrogenic field oxides have been studied. In order to assess the damage due to neutrons alone, it is necessary to account for the damage produced by the accompanying gamma rays from neutron radiation. This is done by measuring the intensity of gamma radiation accompanying neutrons at different neutron fluences at the irradiation position. MOS capacitor structures were subjected to neutron radiation in a swimming pool type of reactor. Other samples from the same batch were then subjected to an equivalent dose of gamma radiation from a Co sup 6 sup 0 source. The difference in the damage observed was used to characterize the damage caused by neutrons. It is observed that neutrons, though uncharged, are capable of causing ionization damage. This damage is found to be significant when the radiation is performed under biased conditions. Nitridation in different ambients is found to improve the radi...

  1. Spreading widths of doorway states

    Energy Technology Data Exchange (ETDEWEB)

    De Pace, A., E-mail: depace@to.infn.i [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, via P. Giuria 1, I-10125 Torino (Italy); Molinari, A. [Dipartimento di Fisica Teorica dell' Universita di Torino, via P. Giuria 1, I-10125 Torino (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Torino, via P. Giuria 1, I-10125 Torino (Italy); Weidenmueller, H.A. [Max-Planck-Institut fuer Kernphysik, D-69029 Heidelberg (Germany)

    2011-01-01

    As a function of energy E, the average doorway strength function S(E)-bar of a doorway state is commonly assumed to be Lorentzian in shape and characterized by two parameters, the peak energy E{sub 0} and the spreading width {Gamma}{sup {down_arrow}}. The simple picture is modified when the density of background states that couple to the doorway state changes significantly in an energy interval of size {Gamma}{sup {down_arrow}}. For that case we derive an approximate analytical expression for S(E)-bar. We test our result successfully against numerical simulations. Our result may have important implications for shell-model calculations.

  2. N-Widths and Average Widths of Besov Classes in Sobolev Spaces

    Institute of Scientific and Technical Information of China (English)

    Gui Qiao XU; Yong Sheng SUN; Yong Ping LIU

    2006-01-01

    In this paper, we consider the n-widths and average widths of Besov classes in the usual Sobolev spaces. The weak asymptotic results concerning the Kolmogorov n-widths, the linear n-widths,the Gel'fand n-widths, in the Sobolev spaces on Td, and the infinite-dimensional widths and the average widths in the Sobolev spaces on Rd are obtained, respectively.

  3. Neutron guide shielding for the BIFROST spectrometer at ESS

    DEFF Research Database (Denmark)

    Mantulnikovs, K.; Bertelsen, M.; Cooper-Jensen, C.P.;

    We report on the study of fast-neutron background for the BIFROST spectrometer at ESS. We investigate the effect of background radiation induced by the interaction of fast neutrons from the source with the material of the neutron guide and devise a reasonable fast, thermal/cold neutron shielding...

  4. Control of radioactive wastes and coupling of neutron/gamma measurements: use of radiative capture for the correction of matrix effects that penalize the fissile mass measurement by active neutron interrogation; Controle des dechets radioactifs et couplage de mesures neutron/gamma: exploitation de la capture radiative pour corriger les effets de matrice penalisant la mesure de la masse fissile par interrogation neutronique active

    Energy Technology Data Exchange (ETDEWEB)

    Loche, F

    2006-10-15

    In the framework of radioactive waste drums control, difficulties arise in the nondestructive measurement of fissile mass ({sup 235}U, {sup 239}Pu..) by Active Neutron Interrogation (ANI), when dealing with matrices containing materials (Cl, H...) influencing the neutron flux. The idea is to use the neutron capture reaction (n,{gamma}) to determine the matrix composition to adjust the ANI calibration coefficient value. This study, dealing with 118 litres, homogeneous drums of density less than 0,4 and composed of chlorinated and/or hydrogenated materials, leads to build abacus linking the {gamma} ray peak areas to the ANI calibration coefficient. Validation assays of these abacus show a very good agreement between the corrected and true fissile masses for hydrogenated matrices (max. relative standard deviation: 23 %) and quite good for chlorinated and hydrogenated matrices (58 %). The developed correction method improves the measured values. It may be extended to 0,45 density, heterogeneous drums. (author)

  5. Observation of Neutron Skyshine from an Accelerator Based Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Franklyn, C. B. [Radiation Science Department, Necsa, PO Box 582, Pretoria 0001 (South Africa)

    2011-12-13

    A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

  6. Thin-Film Coated Detectors for Neutron Detection

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, Douglas S.; Gersch, Holly K.; Sanders, Jeffrey D.; Lindsay, John T. [Univ. of Michigan, Ann Arbor (United States); Klann, Raymond T. [Argonne National Lab., Argonne (United States)

    2001-09-15

    Semiconductor diode detectors coated with neutron reactive material are presently under investigation for various uses, such as remote sensing of thermal neutrons, fast neutron counting, and thermal neutron radiography. Theory indicates that single-coated devices can yield thermal neutron efficiencies from 4% to 11%, which is supported by experimental evidence. Radiation endurance measurements indicates that the devices function well up to a limiting thermal neutron fluence of 10{sup 13}/cm{sup 2}, beyond which noticeable degradation occurs. Thermal neutron contrast images of step wedges and simple phantoms, taken with dual in-line pixel devices, show promise for thermal neutron imaging detectors.

  7. Evaluation of defects induced by neutron radiation in reactor pressure vessels steels; Evaluacion de los defectos inducidos por la radiacion neutronica en los aceros de vasijas

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Jimenez, J.

    1978-07-01

    We have developed a method for calculating the production of neutron induced defects (depleted zone and crowdions) in ferritic pressure vessel steels for different neutron spectra. They have been analysed both the recoil primary atoms produced by elastic and inelastic collisions with fast neutrons and the ones produced by gamma-ray emission by thermal neutron absorption. Theoretical modelling of increasing in the ductile-brittle transition temperature of ferritic steels has been correlated with experimental data at irradiation temperature up to 400 degree centigree (Author) 15 refs.

  8. Simple dynamic electromagnetic radiation detector

    Science.gov (United States)

    Been, J. F.

    1972-01-01

    Detector monitors gamma dose rate at particular position in a radiation facility where a mixed neutron-gamma environment exists, thus determining reactor power level changes. Device also maps gamma intensity profile across a neutron-gamma beam.

  9. Neutron Repulsion

    OpenAIRE

    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...

  10. Neutron production station ESS-BILBAO; Estacion de produccion de neutrones de ESS-BILBAO

    Energy Technology Data Exchange (ETDEWEB)

    Vicente Bueno, J. Pe. de; Bermejo, J.; Fraile Santiago, T.

    2012-07-01

    The ESS-Bilbao installation produces neutrons by nuclear reactions stripping energy 50 MeV protons on a target of beryllium. the Neutron Production Station would have a target and would allow condition the neutron energy, maximize their performance, provide structural support to the whole, the high power cooling and radiation shielding received abroad.

  11. Neutronics studies for the design of the European DEMO vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Flammini, Davide, E-mail: davide.flammini@enea.it [ENEA, Fusion Technical Unit, Nuclear Technologies Laboratory, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Villari, Rosaria; Moro, Fabio; Pizzuto, Aldo [ENEA, Fusion Technical Unit, Nuclear Technologies Laboratory, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Bachmann, Christian [EUROfusion Consortium, Boltzmannstr. 2, 85748 Garching (Germany)

    2016-11-01

    Highlights: • MCNP calculation of nuclear heating, damage, helium production and neutron flux in DEMO HCLL and HCPB vacuum vessel at the inboard equatorial plane. • Study of impact of the poloidal gap between blanket modules, for several gap width, on vacuum vessel nuclear quantities. • Effect of the gap on nuclear heating result to be moderate, however high values of nuclear heating are found, even far from the gap with HCLL blanket. • Radiation damage limit of 2.75 DPA is met with a 1 cm wide gap. Helium production results very sensitive to the gap width. • Comparison between HCLL and HCPB blankets is shown for nuclear heating and neutron flux in the vacuum vessel. - Abstract: The DEMO vacuum vessel, a massive water cooled double-walled steel vessel, is located behind breeding blankets and manifolds and it will be subjected to an intense neutron and photon irradiation. Therefore, a proper evaluation of the vessel nuclear heat loads is required to assure adequate cooling and, given the significant lifetime neutron fluence of DEMO, the radiation damage limit of the vessel needs to be carefully controlled. In the present work nuclear heating, radiation damage (DPA), helium production, neutron and photon fluxes have been calculated on the vacuum vessel at the inboard by means of MCNP5 using a 3D Helium Cooled Lithium Lead (HCLL) DEMO model with 1572 MW of fusion power. In particular, the effect of the poloidal gap between the breeding-blanket segments on vacuum vessel nuclear loads has been estimated varying the gap width from 0 to 5 cm. High values of the nuclear heating (≈1 W/cm{sup 3}), which might cause intense thermal stresses, were obtained in inboard equatorial zone. The effect of the poloidal gap on the nuclear heating resulted to be moderate (within 30%). The radiation damage limit of 2.75 DPA on the vessel is almost met with 1 cm of poloidal gap over DEMO lifetime. A comparison with Helium Cooled Pebble Bed blanket is also provided.

  12. Characterization of bauxite residue (red mud) for (235)U, (238)U, (232)Th and (40)K using neutron activation analysis and the radiation dose levels as modeled by MCNP.

    Science.gov (United States)

    Landsberger, S; Sharp, A; Wang, S; Pontikes, Y; Tkaczyk, A H

    2017-07-01

    This study employs thermal and epithermal neutron activation analysis (NAA) to quantitatively and specifically determine absorption dose rates to various body parts from uranium, thorium and potassium. Specifically, a case study of bauxite residue (red mud) from an industrial facility was used to demonstrate the feasibility of the NAA approach for radiological safety assessment, using small sample sizes to ascertain the activities of (235)U, (238)U, (232)Th and (40)K. This proof-of-concept was shown to produce reliable results and a similar approach could be used for quantitative assessment of other samples with possible radiological significance. (238)U and (232)Th were determined by epithermal and thermal neutron activation analysis, respectively. (235)U was determined based on the known isotopic ratio of (238)U/(235)U. (40)K was also determined using epithermal neutron activation analysis to measure total potassium content and then subtracting its isotopic contribution. Furthermore, the work demonstrates the application of Monte Carlo Neutral-Particle (MCNP) simulations to estimate the radiation dose from large quantities of red mud, to assure the safety of humans and the surrounding environment. Phantoms were employed to observe the dose distribution throughout the human body demonstrating radiation effects on each individual organ. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. 14 CFR 121.115 - Route width.

    Science.gov (United States)

    2010-01-01

    ... Route width. (a) Routes and route segments over Federal airways, foreign airways, or advisory routes have a width equal to the designated width of those airways or advisory routes. Whenever the... clearance. (2) Minimum en route altitudes. (3) Ground and airborne navigation aids. (4) Air traffic density...

  14. Clique-width of unit interval graphs

    OpenAIRE

    Lozin, Vadim V.

    2007-01-01

    The clique-width is known to be unbounded in the class of unit interval graphs. In this paper, we show that this is a minimal hereditary class of unbounded clique-width, i.e., in every hereditary subclass of unit interval graphs the clique-width is bounded by a constant.

  15. Synchrotron radiation powder X-ray and neutron diffraction studies on novel Y{sub 3}Al{sub 2} hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Sato, T. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8577 (Japan); Ikeda, K. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8577 (Japan)], E-mail: kikeda@imr.tohoku.ac.jp; Ohoyama, K.; Watanabe, N.; Orimo, S. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8577 (Japan)

    2009-07-29

    Crystal structures of Y{sub 3}Al{sub 2} hydrides with dehydriding/rehydriding properties were clarified using synchrotron radiation powder X-ray diffraction measurements; Y{sub 3}Al{sub 2}H{sub 2.2}: a = 8.29744(4) A and c = 7.58858(4) A in space group P4{sub 2}/mnm (No. 136); Y{sub 3}Al{sub 2}H{sub 5.5}: a = 8.5043(1) A, b = 8.3268(1) A and c = 7.5913(1) A in space group Pnnm (No. 58); and Y{sub 3}Al{sub 2}H{sub 6.5}: a = 12.2544(2) A, b = 12.1332(2) A and c = 14.8268(2) A in space group Ibam (No. 72). All the hydrides maintain the characteristic metal atom arrangements of Y{sub 3}Al{sub 2} that are composed of distorted W (body-centered-cubic; bcc)- and AlB{sub 2}-type slabs. Two H atom sites in Y{sub 3}Al{sub 2}H{sub 2.2} were determined by using a powder neutron diffraction and Rietveld analysis of a deuteride Y{sub 3}Al{sub 2}D{sub 2.33} (a = 8.2850(3) A and c = 7.5832(3) A in space group P4{sub 2}/mnm (No. 136)). One of these sites is inside a tetrahedron coordinated by four Y atoms and located on both sides of the faces shared by the distorted W-type slabs. The other site is inside a triangle coordinated by three Y atoms and located on one side of the faces shared by the distorted AlB{sub 2}-type slabs.

  16. The world’s first pelletized cold neutron moderator at a neutron scattering facility

    Energy Technology Data Exchange (ETDEWEB)

    Ananiev, V.; Belyakov, A.; Bulavin, M.; Kulagin, E.; Kulikov, S.; Mukhin, K.; Petukhova, T.; Sirotin, A.; Shabalin, D.; Shabalin, E.; Shirokov, V.; Verhoglyadov, A., E-mail: verhoglyadov_al@mail.ru

    2014-02-01

    In July 10, 2012 cold neutrons were generated for the first time with the unique pelletized cold neutron moderator CM-202 at the IBR-2M reactor. This new moderator system uses small spherical beads of a solid mixture of aromatic hydrocarbons (benzene derivatives) as the moderating material. Aromatic hydrocarbons are known as the most radiation-resistant hydrogenous substances and have properties to moderate slow neutrons effectively. Since the new moderator was put into routine operation in September 2013, the IBR-2 research reactor of the Frank Laboratory of Neutron Physics has consolidated its position among the world’s leading pulsed neutron sources for investigation of matter with neutron scattering methods.

  17. Outline of spallation neutron source engineering

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Noboru [Center for Neutron Science, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    2001-01-01

    Slow neutrons such as cold and thermal neutrons are unique probes which can determine structures and dynamics of condensed matter in atomic scale. The neutron scattering technique is indispensable not only for basic sciences such as condensed matter research and life science, but also for basic industrial technology in 21 century. It is believed that to survive in the science-technology competition in 21 century would be almost impossible without neutron scattering. However, the intensity of neutrons presently available is much lower than synchrotron radiation sources, etc. Thus, R and D of intense neutron sources become most important. The High-Intensity Proton Accelerator Project is now being promoted jointly by Japan Atomic Energy Research Institute and High Energy Accelerator Research Organization, but there has so far been no good text which covers all the aspects of pulsed spallation neutron sources. The present review was prepare aiming at giving a better understanding on pulsed spallation neutron sources not only to neutron source researchers but also more widely to neutron scattering researchers and accelerator scientists in this field. The contents involve, starting from what is neutron scattering and what neutrons are necessary for neutron scattering, what is the spallation reaction, how to produce neutrons required for neutron scattering more efficiently, target-moderator-reflector neutronics and its engineering, shielding, target station, material issues, etc. The author have engaged in R and D of pulsed apallation neutron sources and neutron scattering research using them over 30 years. The present review is prepared based on the author's experiences with useful information obtained through ICANS collaboration and recent data from the JSNS (Japanese Spallation Neutron Source) design team. (author)

  18. A system of materials composition and geometry arrangement for fast neutron beam thermalization: An MCNP study

    Science.gov (United States)

    Uhlář, Radim; Alexa, Petr; Pištora, Jaromír

    2013-03-01

    Compact deuterium-tritium neutron generators emit fast neutrons (14.2 MeV) that have to be thermalized for neutron activation analysis experiments. To maximize thermal neutron flux and minimize epithermal and fast neutron fluxes across the output surface of the neutron generator facility, Monte Carlo calculations (MCNP5; Los Alamos National Laboratory) for different moderator types and widths and collimator and reflector designs have been performed. A thin lead layer close to the neutron generator as neutron multiplier followed by polyethylene moderator and surrounded by a massive lead and nickel collimator and reflector was obtained as the optimum setup.

  19. New sources and instrumentation for neutrons in biology

    DEFF Research Database (Denmark)

    Teixeira, S. C. M.; Zaccai, G.; Ankner, J.

    2008-01-01

    Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed.......Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed....

  20. New sources and instrumentation for neutrons in biology

    DEFF Research Database (Denmark)

    Teixeira, S. C. M.; Zaccai, G.; Ankner, J.;

    2008-01-01

    Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed.......Neutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed....

  1. Palindromic widths of nilpotent and wreath products

    Indian Academy of Sciences (India)

    Valeriy G Bardakov; Oleg V Bryukhanov; Krishnendu Gongopadhyay

    2017-02-01

    We prove that the nilpotent product of a set of groups $A_1, \\ldots , A_s$ has finite palindromic width if and only if the palindromic widths of $A_i$, $i = 1, \\ldots , s$, are finite. We give a new proof that the commutator width of $F_n \\wr K$ is infinite, where $F_n$ is a free group of rank $n\\geq 2$ and $K$ is a finite group. This result, combining with a result of Fink [9] gives examples of groups with infinite commutator width but finite palindromic width with respect to some generating set.

  2. Temperature Dependences of the Quantum-Mechanical and Semi-Classical Spectral-Line Widths and the Separation 0 of the Impact and Non-Impact Regions for an Ar-Perturbed/K-Radiator System

    Directory of Open Access Journals (Sweden)

    W. C. Kreye

    2010-01-01

    Full Text Available Quantum-mechanical and semi-classical spectral-line shapes are computed at =400, 800, and 1000 K for the line core of the 5802 Å line of the Ar-Perturbed/K-Radiator system. HWHMs ('s are measured from computed full spectral-line shapes. The final-state pseudopotential is for the 721/2 state, and the initial-state potential is for the 423/2,3/2 state. Three high-pressure (P log(—versus—log( curves, corresponding to the non-impact region, intersect a similar set of low-P, impact-region curves at intersections, 0's. Similarly, for two sets of log(—versus—log( curves, which yield intersections, 0's, where is the perturber density. These 0's and 0's separate the two regions and represent the upper limits of the impact regions. A specific validity condition for the impact region is given by the equation ≤0. From an earlier spectroscopic, Fabry-Perot paper, expt=0.021 cm−1 at =400 K and =10 torr. Two theoretical values, theor=0.025 and 0.062 cm−1 corresponding to two different pseudo-potentials, are reported. Two -dependent figures are given, in which the first shows an increase in the impact region with , based on as the basic parameter, and the second which shows a decrease in the impact region with , based on as the basic parameter.

  3. Clinical Report on Californium-252 Neutron Intraluminal Brachytherapy Combined with External Irradiation for Cervical Carcinoma Treatment

    Institute of Scientific and Technical Information of China (English)

    Huanyu Zhao; Keming Wang; Jian Sun; Xin Geng; Weiming Zhang

    2006-01-01

    OBJECTIVE To observe the curative effects and complications of californium-252 (252Cf) neutron intraluminal brachytherapy (IBT) combined with external irradiation (El) for treatment of cervical carcinoma.METHODS From December 2000 to December 2004, 128 cases of cervical carcinoma staged into ⅡA~ⅢB according to the International Federation of Gynecology and Obstetrics (FIGO) standards were treated with 252Cf neutron IBT using 8~10 Gy per fraction, once a week. The total dose at reference A point was 36~40 Gy in 4~5 fractions. From the second day after 252Cf neutron IBT treatment, the whole pelvic cavity was treated with 60Co γ-ray El, applying 2 Gy per fraction, 4 times per week. After 20~25 Gy of El, the center of the whole pelvic field was blocked with 4 cm of lead in width. The total dose of El was 45~50 Gy.RESULTS The short-term therapeutic effects were CR 95.3% and PR 4.7%. The 3 and 5-year local control rates were 93.5% and 87.9%. The overall 3-year survival rate was 87.5% and for Stages Ⅱ and Ⅲ , 90.9%and 81.5% respectively; the overall 5-year survival rate was 70% and for Stages Ⅱ and Ⅲ, 76.2% and 61% respectively. The rate of radiation complications was 4.7% for radiation cystitis, 7.8% for radiation proctitis, 6.3%for vagina contracture and adhesion and 5.5% for protracted radiation proctitis.CONCLUSION An combination of 252Cf neutron IBT with El for treatment of cervical carcinoma can be well-tolerated by cervical carcinoma patients. The rate of local tumor control is high and radiation complications are few.

  4. Sensitivity of a new-developed neutron detector

    Institute of Scientific and Technical Information of China (English)

    PENG Tai-Ping; ZHU Xue-Bin; YANG Hong-Qiong; YANG Jian-Lun; YANG Gao-Zhao; LI Lin-Bo; SONG Xian-Cai

    2005-01-01

    We develop a kind of neutron detector, which consists of a polyethylene thin film and two PIN semiconductors connected face-to-face. The detector is insensitive to γ-rays. Its sensitivity to neutron has been calculated with MCNP program and calibrated by experiments, and the results indicate that the neutron sensitivity of the compensation detector will vary with polyethylene converter. The compensation PIN detector can be employed to measure pulse neutron in neutron and gamma mixture radiation field.

  5. A Compact High-Energy Neutron Spectrometer

    CERN Document Server

    Brooks, F D; Buffler, A; Dangendorf, V; Herbert, M S; Jones, D T L; Nchodu, M R; Nolte, R; Smit, F D

    2007-01-01

    A compact liquid organic neutron spectrometer (CLONS) based on a single NE213 liquid scintillator (5 cm diam. x 5 cm) is described. The spectrometer is designed to measure neutron fluence spectra over the energy range 2-200 MeV and is suitable for use in neutron fields having any type of time structure. Neutron fluence spectra are obtained from measurements of two-parameter distributions (counts versus pulse height and pulse shape) using the Bayesian unfolding code MAXED. Calibration and test measurements made using a pulsed neutron beam with a continuous energy spectrum are described and the application of the spectrometer to radiation dose measurements is discussed.

  6. Plutonium radiation surrogate

    Science.gov (United States)

    Frank, Michael I [Dublin, CA

    2010-02-02

    A self-contained source of gamma-ray and neutron radiation suitable for use as a radiation surrogate for weapons-grade plutonium is described. The source generates a radiation spectrum similar to that of weapons-grade plutonium at 5% energy resolution between 59 and 2614 keV, but contains no special nuclear material and emits little .alpha.-particle radiation. The weapons-grade plutonium radiation surrogate also emits neutrons having fluxes commensurate with the gamma-radiation intensities employed.

  7. Pixelated neutron image plates

    Science.gov (United States)

    Schlapp, M.; Conrad, H.; von Seggern, H.

    2004-09-01

    Neutron image plates (NIPs) have found widespread application as neutron detectors for single-crystal and powder diffraction, small-angle scattering and tomography. After neutron exposure, the image plate can be read out by scanning with a laser. Commercially available NIPs consist of a powder mixture of BaFBr : Eu2+ and Gd2O3 dispersed in a polymer matrix and supported by a flexible polymer sheet. Since BaFBr : Eu2+ is an excellent x-ray storage phosphor, these NIPs are particularly sensitive to ggr-radiation, which is always present as a background radiation in neutron experiments. In this work we present results on NIPs consisting of KCl : Eu2+ and LiF that were fabricated into ceramic image plates in which the alkali halides act as a self-supporting matrix without the necessity for using a polymeric binder. An advantage of this type of NIP is the significantly reduced ggr-sensitivity. However, the much lower neutron absorption cross section of LiF compared with Gd2O3 demands a thicker image plate for obtaining comparable neutron absorption. The greater thickness of the NIP inevitably leads to a loss in spatial resolution of the image plate. However, this reduction in resolution can be restricted by a novel image plate concept in which a ceramic structure with square cells (referred to as a 'honeycomb') is embedded in the NIP, resulting in a pixelated image plate. In such a NIP the read-out light is confined to the particular illuminated pixel, decoupling the spatial resolution from the optical properties of the image plate material and morphology. In this work, a comparison of experimentally determined and simulated spatial resolutions of pixelated and unstructured image plates for a fixed read-out laser intensity is presented, as well as simulations of the properties of these NIPs at higher laser powers.

  8. Within the framework of the new fuel cycle {sup 232}Th/{sup 233}U, determination of the {sup 233}Pa(n.{gamma}) radiative capture cross section for neutron energies ranging between 0 and 1 MeV; Dans le cadre du nouveau cycle de combustible {sup 232}Th/{sup 233}U, determination de la section efficace de capture radiative {sup 233}Pa(n,{gamma}) pour des energies de neutrons comprises entre 0 et 1 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, S

    2004-10-15

    The Thorium cycle Th{sup 232}/U{sup 233} may face brilliant perspectives through advanced concepts like molten salt reactors or accelerator driven systems but it lacks accurate nuclear data concerning some nuclei. Pa{sup 233} is one of these nuclei, its high activity makes the direct measurement of its radiative neutron capture cross-section almost impossible. This difficulty has been evaded by considering the transfer reaction Th{sup 232}(He{sup 3},p)Pa{sup 234}* in which the Pa{sup 234} nucleus is produced in various excited states according to the amount of energy available in the reaction. The first chapter deals with the thorium cycle and its assets to contribute to the quenching of the fast growing world energy demand. The second chapter gives a detailed description of the experimental setting. A scintillation detector based on deuterated benzene (C{sub 6}D{sub 6}) has been used to counter gamma ray cascades. The third chapter is dedicated to data analysis. In the last chapter we compare our experimental results with ENDF and JENDL data and with computed values from 2 statistical models in the 0-1 MeV neutron energy range. Our results disagree clearly with evaluated data: our values are always above ENDF and JENDL data but tend to near computed values. We have also perform the measurement of the radiative neutron cross-section of Pa{sup 231} for a 110 keV neutron: {sigma}(n,{gamma}) 2.00 {+-} 0.14 barn. (A.C.)

  9. Fusion neutronics

    CERN Document Server

    Wu, Yican

    2017-01-01

    This book provides a systematic and comprehensive introduction to fusion neutronics, covering all key topics from the fundamental theories and methodologies, as well as a wide range of fusion system designs and experiments. It is the first-ever book focusing on the subject of fusion neutronics research. Compared with other nuclear devices such as fission reactors and accelerators, fusion systems are normally characterized by their complex geometry and nuclear physics, which entail new challenges for neutronics such as complicated modeling, deep penetration, low simulation efficiency, multi-physics coupling, etc. The book focuses on the neutronics characteristics of fusion systems and introduces a series of theories and methodologies that were developed to address the challenges of fusion neutronics, and which have since been widely applied all over the world. Further, it introduces readers to neutronics design’s unique principles and procedures, experimental methodologies and technologies for fusion systems...

  10. 含碳化硼的吸收和屏蔽中子辐射涂料的研究%Boron Carbide Containing Paint Absorbing and Shielding Neutron Radiation

    Institute of Scientific and Technical Information of China (English)

    黄益平; 冯惠生; 梁璐; 徐姣; 张卫江

    2011-01-01

    对碳化硼(B4C)/环氧树脂涂料合成工艺进行研究,制得一种以793树脂作为固化剂的能屏蔽和吸收中子辐射的涂料.对B4C/环氧树脂涂料的成膜条件及不同含量B4C涂料的硬度、抗冲击性、附着力和柔韧性等物理机械性能进行测试研充结果表明,含有30% B4C的环氧树脂涂料的总体机械性能最佳.在此基础上,考察了不同涂膜厚度下B4C/环氧树脂涂料的防中子辐射的性能,薄膜厚度超过300 μm时,可以有效屏蔽中子射线.%The synthesis technology of boron carbide (B4C)/epoxy resin paint was investigated, and the paint with the ability of absorbing and shielding the neutron radiation, solidified by 793 resin, was obtained. The film-forming conditions of B4C / epoxy resin paint were treated; meanwhile, the relationship between the different contents of B4C in the paint and hardness, impact resistance, adhesion, flexibility and other physical testing of mechanical properties was studied. The conclusion was obtained that the overall machinery of B4C/epoxy paint has better performance with 30% B4C. Furthermore, The anti-neutron radiation performance of B4C/epoxy paint with different film thicknesses was also examined. Results show that effective neutron radiation shielding can be achieved when the film thickness exceeds 300 nm.

  11. Modeling neutron guides using Monte Carlo simulations

    CERN Document Server

    Wang, D Q; Crow, M L; Wang, X L; Lee, W T; Hubbard, C R

    2002-01-01

    Four neutron guide geometries, straight, converging, diverging and curved, were characterized using Monte Carlo ray-tracing simulations. The main areas of interest are the transmission of the guides at various neutron energies and the intrinsic time-of-flight (TOF) peak broadening. Use of a delta-function time pulse from a uniform Lambert neutron source allows one to quantitatively simulate the effect of guides' geometry on the TOF peak broadening. With a converging guide, the intensity and the beam divergence increases while the TOF peak width decreases compared with that of a straight guide. By contrast, use of a diverging guide decreases the intensity and the beam divergence, and broadens the width (in TOF) of the transmitted neutron pulse.

  12. Measurementof photo-neutron dose from an 18-MV medical linac using a foil activation method in view of radiation protection of patients

    Energy Technology Data Exchange (ETDEWEB)

    Yuecel, Haluk; Kolbasi, Asuman; Yueksel, Alptug Oezer [Ankara University, Institute of Nuclear Sciences, Ankara (Turkmenistan); Cobanbas, Ibrahim; Kaya, Vildan [Sueleyman Demirel University, School of Medicine, Dept. of Radiation Oncology, Isparta (Turkmenistan)

    2016-04-15

    High-energy linear accelerators are increasingly used in the medical field. However, the unwanted photo-neutrons can also be contributed to the dose delivered to the patients during their treatments. In this study, neutron fluxes were measured in a solid water phantom placed at the isocenter 1-m distance from the head of an 18-MV linac using the foil activation method. The produced activities were measured with a calibrated well-type Ge detector. From the measured fluxes, the total neutron fluence was found to be (1.17 ± 0.06) X 10{sup 7} n/cm{sup 2} per Gy at the phantom surface in a 20 X 20 cm{sup 2} X-ray field size. The maximum photo-neutron dose was measured to be 0.67 ± 0.04 mSv/Gy at d{sub max} = 5 cm depth in the phantom at isocenter. The present results are compared with those obtained for different field sizes of 10 X 10cm{sup 2}, 15 X 15cm{sup 2}, and 20 X 20cm{sup 2} from 10-, 15-, and 18-MV linacs. Additionally, ambient neutron dose equivalents were determined at different locations in the room and they were found to be negligibly low. The results indicate that the photo-neutron dose at the patient position is not a negligible fraction of the therapeutic photon dose. Thus, there is a need for reduction of the contaminated neutron dose by taking some additional measures, for instance, neutron absorbing-protective materials might be used as aprons during the treatment.

  13. Neutron Albedo

    CERN Document Server

    Ignatovich, V K

    2005-01-01

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

  14. Neutron Star Physics and EOS

    Directory of Open Access Journals (Sweden)

    Lattimer James M.

    2016-01-01

    Full Text Available Neutron stars are important because measurement of their masses and radii will determine the dense matter equation of state. They will constrain the nuclear matter symmetry energy, which controls the neutron star matter pressure and the interior composition, and will influence the interpretation of nuclear experiments. Astrophysical observations include pulsar timing, X-ray bursts, quiescent low-mass X-ray binaries, pulse profiles from millisecond pulsars, neutrino observations from gravitational collapse supernovae,and gravitational radiation from compact object mergers. These observations will also constrain the neutron star interior, including the properties of superfluidity there, and determine the existence of a possible QCD phase transition.

  15. NECTAR-A fission neutron radiography and tomography facility

    Energy Technology Data Exchange (ETDEWEB)

    Buecherl, T., E-mail: thomas.buecherl@radiochemie.de [Technische Universitaet Muenchen, Lehrstuhl fuer Radiochemie (RCM), Walther-Meissner-Str. 3, 85748 Garching (Germany); Lierse von Gostomski, Ch. [Technische Universitaet Muenchen, Lehrstuhl fuer Radiochemie (RCM), Walther-Meissner-Str. 3, 85748 Garching (Germany); Breitkreutz, H.; Jungwirth, M.; Wagner, F.M. [Technische Universitaet Muenchen, Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) (Germany)

    2011-09-21

    NECTAR (Neutron Computerized Tomography and Radiography) is a versatile facility for radiographic and tomographic investigations as well as for neutron activation experiments using fission neutrons. The radiation sources for this facility are two plates of highly enriched uranium situated in the moderator vessel in FRM II. Thermal neutrons originating from the main fuel element of the reactor generate in these plates fast neutrons. These can escape through a horizontal beam tube without moderation. The beam can be filtered and manipulated in order to reduce the accompanying gamma radiation and to match the specific experimental tasks. A summary of the main parameters required for experimental set-up and (quantitative) data evaluation is presented. The (measured) spectra of the neutron and gamma radiations are shown along with the effect of different filters on their behavior. The neutron and gamma fluxes, dose rates, L/D-ratios, etc. and the main parameters of the actually used detection systems for neutron imaging are given, too.

  16. NEUTRON CROSS SECTION EVALUATIONS OF FISSION PRODUCTS BELOW THE FAST ENERGY REGION

    Energy Technology Data Exchange (ETDEWEB)

    OH,S.Y.; CHANG,J.; MUGHABGHAB,S.

    2000-05-11

    Neutron cross section evaluations of the fission-product isotopes, {sup 95}Mo, {sup 99}Tc, {sup 101}Ru, {sup 103}Rh, {sup 105}Pd, {sup 109}Ag, {sup 131}Xe, {sup 133}Cs, {sup 141}Pr, {sup 141}Nd, {sup 147}Sm, {sup 149}Sm, {sup 150}Sm, {sup 151}Sm, {sup 152}Sm, {sup 153}Eu, {sup 155}Gd, and {sup 157}Gd were carried out below the fast neutron energy region within the framework of the BNL-KAERI international collaboration. In the thermal energy region, the energy dependence of the various cross-sections was calculated by applying the multi-level Breit-Wigner formalism. In particular, the strong energy dependence of the coherent scattering lengths of {sup 155}Gd and {sup 157}Gd were determined and were compared with recent calculations of Lynn and Seeger. In the resonance region, the recommended resonance parameters, reported in the BNL compilation, were updated by considering resonance parameter information published in the literature since 1981. The s-wave and, if available, p-wave reduced neutron widths were analyzed in terms of the Porter-Thomas distribution to determine the average level spacings and the neutron strength functions. Average radiative widths were also calculated from measured values of resolved energy resonances. The average resonance parameters determined in this study were compared with those in the BNL and other compilations, as well as the ENDF/B-VI, JEF-2.2, and JENDL-3.2 data libraries. The unresolved capture cross sections of these isotopes, computed with the determined average resonance parameters, were compared with measurements, as well as the ENDF/B-VI evaluations. To achieve agreement with the measurements, in a few cases minor adjustments in the average resonance parameters were made. Because of astrophysical interest, the Maxwellian capture cross sections of these nuclides at a neutron temperature of 30 keV were computed and were compared with other compilations and evaluations.

  17. Inelastic Neutron Scattering from Cerium under Pressure

    DEFF Research Database (Denmark)

    Rainford, B. D.; Buras, B.; Lebech, Bente

    1977-01-01

    Inelastic neutron scattering from Ce metal at 300 K was studied both below and above the first order γ-α phase transition, using a triple axis spectrometer. It was found that (a) there is no indication of any residual magnetic scattering in the collapsed α phase, and (b) the energy width of the p......Inelastic neutron scattering from Ce metal at 300 K was studied both below and above the first order γ-α phase transition, using a triple axis spectrometer. It was found that (a) there is no indication of any residual magnetic scattering in the collapsed α phase, and (b) the energy width...

  18. Approximation Algorithms for Directed Width Parameters

    CERN Document Server

    Kintali, Shiva; Kumar, Akash

    2011-01-01

    Treewidth of an undirected graph measures how close the graph is to being a tree. Several problems that are NP-hard on general graphs are solvable in polynomial time on graphs with bounded treewidth. Motivated by the success of treewidth, several directed analogues of treewidth have been introduced to measure the similarity of a directed graph to a directed acyclic graph (DAG). Directed treewidth, D-width, DAG-width, Kelly-width and directed pathwidth are some such parameters. In this paper, we present the first approximation algorithms for all these five directed width parameters. For directed treewidth and D-width we achieve an approximation factor of O(sqrt{logn}). For DAG-width, Kelly-width and directed pathwidth we achieve an O({\\log}^{3/2}{n}) approximation factor. Our algorithms are constructive, i.e., they construct the decompositions associated with these parameters. The width of these decompositions are within the above mentioned factor of the corresponding optimal width.

  19. Width Distributions for Convex Regular Polyhedra

    CERN Document Server

    Finch, Steven R

    2011-01-01

    The mean width is a measure on three-dimensional convex bodies that enjoys equal status with volume and surface area [Rota]. As the phrase suggests, it is the mean of a probability density f. We verify formulas for mean widths of the regular tetrahedron and the cube. Higher-order moments of f_tetra and f_cube have not been examined until now. Assume that each polyhedron has edges of unit length. We deduce that the mean square width of the regular tetrahedron is 1/3+(3+sqrt(3))/(3*pi) and the mean square width of the cube is 1+4/pi.

  20. The width of 5-dimensional prismatoids

    CERN Document Server

    Matschke, Benjamin; Weibel, Christophe

    2012-01-01

    Santos' construction of counter-examples to the Hirsch conjecture is based on the existence of prismatoids of dimension d of width greater than d. The case d=5 being the smallest one in which this can possibly occur, we here study the width of 5-dimensional prismatoids, obtaining the following results: - There are 5-prismatoids of width six with only 25 vertices, versus the 48 vertices in Santos' original construction. This leads to lowering the dimension of the non-Hirsch polytopes from 43 to only 20. - There are 5-prismatoids with n vertices and width \\Omega(n^(1/2)) for arbitrarily large n.

  1. CMOS-Based Neutron Spectroscopic Dosimeter (CNSD) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Monitoring space radiation and the dose received by astronauts is important, especially for future long-duration missions. Neutrons contribute a significant...

  2. Tutorial on Neutron Physics in Dosimetry

    CERN Document Server

    Pomp, S

    2009-01-01

    Almost since the time of the discovery of the neutron more than 70 years ago, efforts have been made to understand the effects of neutron radiation on tissue and, eventually, to use neutrons for cancer treatment. In contrast to charged particle or photon radiations which directly lead to release of electrons, neutrons interact with the nucleus and induce emission of several different types of charged particles such as protons, alpha particles or heavier ions. Therefore, a fundamental understanding of the neutron-nucleus interaction is necessary for dose calculations and treatment planning with the needed accuracy. We will discuss the concepts of dose and kerma, neutron-nucleus interactions and have a brief look at nuclear data needs and experimental facilities and set-ups where such data are measured.

  3. Neutron dosimetry; Dosimetria de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    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

  4. Advanced Neutron Spectrometer

    Science.gov (United States)

    Christl, Mark; Dobson, Chris; Norwood, Joseph; Kayatin, Matthew; Apple, Jeff; Gibson, Brian; Dietz, Kurt; Benson, Carl; Smith, Dennis; Howard, David; hide

    2013-01-01

    Energetic neutron measurements remain a challenge for space science investigations and radiation monitoring for human exploration beyond LEO. We are investigating a new composite scintillator design that uses Li6 glass scintillator embedded in a PVT block. A comparison between Li6 and Boron 10 loaded scintillators are being studied to assess the advantages and shortcomings of these two techniques. We present the details of the new Li6 design and results from the comparison of the B10 and Li6 techniques during exposures in a mixed radiation field produced by high energy protons interacting in a target material.

  5. Semiphenomenological approximation of the sums of experimental radiative strength functions for dipole gamma transitions of energy E γ below the neutron binding energy B n for mass numbers in the range 40 ≤ A ≤ 200

    Science.gov (United States)

    Sukhovoj, A. M.; Furman, W. I.; Khitrov, V. A.

    2008-06-01

    The sums of radiative strength functions for primary dipole gamma transitions, k( E1) + k( M1), are approximated to a high precision by a superposition of two functional dependences in the energy range 0.5 125Te, 128I, 137,138,139Ba, 140La, 150Sm, 156,158Gd, 160Tb, 163,164,165Dy, 166Ho, 168Er, 170Tm, 174Yb, 176,177Lu, 181Hf, 182Ta, 183,184,185,187W, 188,190,191,193Os, 192Ir, 196Pt, 198Au, and 200Hg nuclei. It is shown that, in any nuclei, radiative strength functions are a dynamical quantity and that the values of k( E1) + k( M1) for specific energies of gamma transitions and specific nuclei are determined by the structure of decaying and excited levels, at least up to the neutron binding energy B n .

  6. Conceptual design of a camera system for neutron imaging in low fusion power tokamaks

    Science.gov (United States)

    Xie, X.; Yuan, X.; Zhang, X.; Nocente, M.; Chen, Z.; Peng, X.; Cui, Z.; Du, T.; Hu, Z.; Li, T.; Fan, T.; Chen, J.; Li, X.; Zhang, G.; Yuan, G.; Yang, J.; Yang, Q.

    2016-02-01

    The basic principles for designing a camera system for neutron imaging in low fusion power tokamaks are illustrated for the case of the HL-2A tokamak device. HL-2A has an approximately circular cross section, with total neutron yields of about 1012 n/s under 1 MW neutral beam injection (NBI) heating. The accuracy in determining the width of the neutron emission profile and the plasma vertical position are chosen as relevant parameters for design optimization. Typical neutron emission profiles and neutron energy spectra are calculated by Monte Carlo method. A reference design is assumed, for which the direct and scattered neutron fluences are assessed and the neutron count profile of the neutron camera is obtained. Three other designs are presented for comparison. The reference design is found to have the best performance for assessing the width of peaked to broadened neutron emission profiles. It also performs well for the assessment of the vertical position.

  7. Neutron Therapy in the 21st Century

    CERN Document Server

    Kroc, Thomas K

    2014-01-01

    The question of whether or not neutron therapy works has been answered. It is a qualified yes, as is the case with all of radiation therapy. But, neutron therapy has not kept pace with the rest of radiation therapy in terms of beam delivery techniques. Modern photon and proton based external beam radiotherapy routinely implements image-guidance, beam intensity-modulation and 3-dimensional treatment planning. The current iteration of fast neutron radiotherapy does not. Addressing these deficiencies, however, is not a matter of technology or understanding, but resources. The future of neutron therapy lies in better understanding the interaction processes of radiation with living tissue. A combination of radiobiology and computer simulations is required in order to optimize the use of neutron therapy. The questions that need to be answered are: Can we connect the macroscopic with the microscopic? What is the optimum energy? What is the optimum energy spectrum? Can we map the sensitivity of the various tissues of...

  8. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    films or films with magnetic properties. The reason is the peculiar property of neutron light since the mass of a neutron is close to the one of a proton, and since it bears a magnetic moment. The optical properties of matter, when interacting with neutrons, are described by a refractive index......Neutron (and X-ray) reflectometry constitute complementary interfacially sensitive techniques that open access to studying the structure within thin films of both soft and hard condensed matter. Film thickness starts oxide surfaces on bulk substrates, proceeding to (pauci-)molecular layers and up...... to hundreds of nanometers. Thickness resolution for flat surfaces is in the range of few Ǻngstrøm, and as a peculiar benefit, the presence and properties of buried interfaces are accessible. Focus here will be on neutron reflectometry, a technique that is unique in applications involving composite organic...

  9. CR-39 detector based thermal neutron flux measurements, in the photo neutron project

    Energy Technology Data Exchange (ETDEWEB)

    Mameli, A.; Greco, F.; Fidanzio, A. [U.O. di Fisica Sanitaria Policlinico A. Gemelli, Universita Cattolica S. Cuore, Roma (Italy); Fusco, V. [U.O. di Radioterapia, Centro di Riferimento Oncologico della Basilicata, CROB Rionero Pz (Italy); Cilla, S.; D' Onofrio, G.; Grimaldi, L.; Augelli, B.G. [U.O. di Fisica Sanitaria, Centro di Ricerca e Formazione ad Alta Tecnologia nelle Scienze Biomediche dell' Universita Cattolica S. Cuore, Campobasso (Italy); Giannini, G.; Bevilacqua, R.; Totaro, P. [Dipartimento di Fisica-Universita di Trieste e INFN Sez Trieste, Padriciano, Trieste (Italy); Tommasino, L. [Consultant, Via Cassia 1727, 00123 Roma (Italy); Azario, L. [Istituto di Fisica, Universita Cattolica del S. Cuore, Roma (Italy); Piermattei, A. [Istituto di Fisica, Universita Cattolica del S. Cuore, Roma (Italy)], E-mail: a.piermattei@rm.unicatt.it

    2008-08-15

    PhoNeS (photo neutron source) is a project aimed at the production and moderation of neutrons by exploiting high energy linear accelerators, currently used in radiotherapy. A feasibility study has been carried out with the scope in mind to use the high energy photon beams from these accelerators for the production of neutrons suitable for boron neutron capture therapy (BNCT). Within these investigations, it was necessary to carry out preliminary measurements of the thermal neutron component of neutron spectra, produced by the photo-conversion of X-ray radiotherapy beams supplied by three LinAcs: 15 MV, 18 MV and 23 MV. To this end, a simple passive thermal neutron detector has been used which consists of a CR-39 track detector facing a new type of boron-loaded radiator. Once calibrated, this passive detector has been used for the measurement of both the thermal neutron component and the cadmium ratio of different neutron spectra. In addition, bubble detectors with a response highly sensitive to thermal neutrons have also been used. Both thermal neutron detectors are simple to use, very compact and totally insensitive to low-ionizing radiation such as electrons and X-rays. The resultant thermal neutron flux was above 10{sup 6} n/cm{sup 2}s and the cadmium ratio was no greater than 15 for the first attempt of photo-conversion of X-ray radiotherapy beams.

  10. a Portable Pulsed Neutron Generator

    Science.gov (United States)

    Skoulakis, A.; Androulakis, G. C.; Clark, E. L.; Hassan, S. M.; Lee, P.; Chatzakis, J.; Bakarezos, M.; Dimitriou, V.; Petridis, C.; Papadogiannis, N. A.; Tatarakis, M.

    2014-02-01

    The design and construction of a pulsed plasma focus device to be used as a portable neutron source for material analysis such as explosive detection using gamma spectroscopy is presented. The device is capable of operating at a repetitive rate of a few Hz. When deuterium gas is used, up to 105 neutrons per shot are expected to be produced with a temporal pulse width of a few tens of nanoseconds. The pulsed operation of the device and its portable size are its main advantage in comparison with the existing continuous neutron sources. Parts of the device include the electrical charging unit, the capacitor bank, the spark switch (spark gap), the trigger unit and the vacuum-fuel chamber / anode-cathode. Numerical simulations are used for the simulation of the electrical characteristics of the device including the scaling of the capacitor bank energies with total current, the pinch current, and the scaling of neutron yields with energies and currents. The MCNPX code is used to simulate the moderation of the produced neutrons in a simplified geometry and subsequently, the interaction of thermal neutrons with a test target and the corresponding prompt γ-ray generation.

  11. Optimization of Shielded Scintillator for Neutron Detection

    Science.gov (United States)

    Belancourt, Patrick; Morrison, John; Akli, Kramer; Freeman, Richard; High Energy Density Physics Team

    2011-10-01

    The High Energy Density Physics group is interested in the basic science of creating a neutron and gamma ray source. The neutrons and gamma rays are produced by accelerating ions via a laser into a target and creating fusion neutrons and gamma rays. A scintillator and photomultiplier tube will be used to detect these neutrons. Neutrons and photons produce ionizing radiation in the scintillator which then activates metastable states. These metastable states have both short and long decay rates. The initial photon count is orders of magnitude higher than the neutron count and poses problems for accurately detecting the neutrons due to the long decay state that is activated by the photons. The effects of adding lead shielding on the temporal response and signal level of the neutron detector will be studied in an effort to minimize the photon count without significant reduction to the temporal resolution of the detector. MCNP5 will be used to find the temporal response and energy deposition into the scintillator by adding lead shielding. Results from the simulations will be shown. Optimization of our scintillator neutron detection system is needed to resolve the neutron energies and neutron count of a novel neutron and gamma ray source.

  12. 14 CFR 121.95 - Route width.

    Science.gov (United States)

    2010-01-01

    .... (a) Approved routes and route segments over U.S. Federal airways or foreign airways (and advisory... designated width of those airways or routes. Whenever the Administrator finds it necessary to determine the width of other approved routes, he considers the following: (1) Terrain clearance. (2) Minimum en route...

  13. Constant Width Planar Computation Characterizes ACC0

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Arnsfelt

    2006-01-01

    We obtain a characterization of ACC0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all...

  14. Constant Width Planar Computation Characterizes ACC0

    DEFF Research Database (Denmark)

    Hansen, K.A.

    2004-01-01

    We obtain a characterization of ACC 0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all...

  15. A Niche Width Model of Optimal Specialization

    NARCIS (Netherlands)

    Bruggeman, Jeroen; Ó Nualláin, Breanndán

    2000-01-01

    Niche width theory, a part of organizational ecology, predicts whether “specialist” or “generalist” forms of organizations have higher “fitness,” in a continually changing environment. To this end, niche width theory uses a mathematical model borrowed from biology. In this paper, we first loosen th

  16. 7 CFR 29.1085 - Width.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Width. 29.1085 Section 29.1085 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Heavy Fleshy Medium Thin Oil Lean Oily Rich Color intensity Pale Weak Moderate Strong Deep. Width...

  17. Radioprotection of intestinal stem cells and whole body radiation lethality from photons and neutrons by prostaglandins along or in combination with WR-2721. Technical report 24 Feb 86-30 Sep 89

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, W.R.

    1990-12-01

    Prostaglandins (PGs) have been shown to protect the gastrointestinal and hematopoietic cell renewal systems from some degree of radiation damage. The mechanism(s) to account for these observations are unknown. Based on preliminary evidence that PGs varied in the degree to which they afforded protection of intestinal stem cells, we studied protection by several PGs and their analogues. The most protective PGs found to date were 16,16 dm PGE2, misoprostol, a PGE1 analogues, and iloprost, a PGI2 analogue. The relative degrees of protection were 400%, 700% and 800% above control values at a dose of 13.5 137 Cs gamma radiation. These three PGs were used for subsequent studies. Iloprost is a stable PG at room temperature and was found to be protective given orally. In addition to radioprotection of the intestinal stem cells, these Pgs increased the LD50/6, LD50/30 and animal longevity through both the gastrointestinal and hematopoietic syndromes. Misoprostol protected the gut from JANUS neutrons and increased animal longevity following neutron irradiation. Although the mechanism for PG-induced radioprotection is unknown, it appears to be different compared to the widely studied amino thiol, WR-2721. Evidence to support this contention came from data showing that all these analogues were additive to the protective effect of Wr-2721.

  18. Spectrometer equipment for neutron spectra measurements in mixed neutron/photon fields

    CERN Document Server

    Chernov, V A; Trykov, L A

    2002-01-01

    The paper describes spectrometer equipment in the IPPE experimental laboratory for neutron spectra measurement in mixed (n,gamma) fields. The laboratory was founded in 1957 and it occupies a leading position in the field of nuclear facilities radiation spectrometry and benchmark experiments in Russia. Spectrometer equipment includes spectrometers based on the organic stilbene scintillator, hydrogen counter and Bonner balls. Basic fields of spectrometer application are mixed radiation neutron spectra measurement of radionuclide sources, of nuclear reactors and accelerators; study of neutron transfer through the material, including benchmark experiments and measurement of neutron spectra in the rooms of nuclear facilities.

  19. Measurement of radiative widths of a2 and π2

    NARCIS (Netherlands)

    Adolph, C.; Akhunzyanov, R.; Alexeev, M. G.; Alexeev, G. D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Austregesilo, A.; Badełek, B.; Balestra, F.; Barth, J.; Baum, G.; Beck, R.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Büchele, M.; Burtin, E.; Capozza, L.; Chiosso, M.; Chung, S. U.; Cicuttin, A.; Crespo, M. L.; Curiel, Q.; Torre, S. Dalla; Dasgupta, S. S.; Dasgupta, S.; Denisov, O. Y.; Donskov, S. V.; Doshita, N.; Duic, V.; Dünnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P. D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M.; Fischer, H.; Franco, C.; du von Hohenesche, Fresne N.; Friedrich, J. M.; Frolov, V.; Gautheron, F.; Gavrichtchouk, O. P.; Gerassimov, S.; Geyer, R.; Gnesi, I.; Gobbo, B.; Goertz, S.; Gorzellik, M.; Grabmuller, S.; Grasso, A.; Grube, B.; Guskov, A.; Guthörl, T.; Haas, F.; Von Harrach, D.; Hahne, D.; Hashimoto, R.; Heinsius, F. H.; Herrmann, F.; Hinterberger, F.; Hoppner, Ch; Horikawa, N.; D'Hose, N.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Y.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Jörg, P.; Joosten, R.; Kabuß, E.; Ketzer, B.; Khaustov, G. V.; Khokhlov, Y. A.; Kisselev, Y.; Klein, F.; Klimaszewski, K.; Koivuniemi, J. H.; Kolosov, V. N.; Kondo, K.; Königsmann, K.; Konorov, I.; Konstantinov, V. F.; Kotzinian, A. M.; Kouznetsov, O.; Kral, Z.; Krämer, M.; Kroumchtein, Z. V.; Kuchinski, N.; Kunne, F.; Kurek, K.; Kurjata, R. P.; Lednev, A. A.; Lehmann, A.; Levorato, S.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G. K.; Marchand, C.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Y. V.; Miyachi, Y.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V. I.; Novy, J.; Nowak, W. D.; Nunes, A. S.; Orlov, I.; Olshevsky, A. G.; Ostrick, M.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Pesek, M.; Platchkov, S.; Pochodzalla, J.; Polyakov, V. A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Reicherz, G.; Rocco, E.; Rychter, A.; Rossiyskaya, N. S.; Ryabchikov, D. I.; Samoylenko, V. D.; Sandacz, A.; Sarkar, S.; Savin, I. A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schlüter, T.; Schmidt, A.; Schmidt, K.; Schmieden, H.; Schönning, K.; Schopferer, S.; Schott, M.; Shevchenko, O. Y.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Takekawa, S.; ter Wolbeek, J.; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Uhl, S.; Uman, I.; Vandenbroucke, M.; Virius, M.; Vondra, J.; Wang, L.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Matsuda, T.; Lichtenstadt, J.; Sznajder, P.; Ziembicki, M.

    2014-01-01

    The COMPASS Collaboration at CERN has investigated the reaction π̄γ → π̄π̄π+ embedded in the Primakoff reaction of 190 GeV pions scattering in the Coulomb field of a lead target, π̄Pb → π̄π̄π+ Pb. Exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at momentum tra

  20. Optimization of Neutron Spectrum in Northwest Beam Tube of Tehran Research Reactor for BNCT, by MCNP Code

    Energy Technology Data Exchange (ETDEWEB)

    Zamani, M. [National Radiation Protection Department - NRPD, Atomic Energy Organization of Iran - AEOI, Tehran (Iran, Islamic Republic of); End of North Kargar st, Atomic Energy Organization of Iran, P.O. Box: 14155-1339, Tehran (Iran, Islamic Republic of); Kasesaz, Y.; Khalafi, H.; Shayesteh, M. [Radiation Application School, Nuclear Science and Technology Research Institute, AEOI, Tehran (Iran, Islamic Republic of)

    2015-07-01

    In order to gain the neutron spectrum with proper components specification for BNCT, it is necessary to design a Beam Shape Assembling (BSA), include of moderator, collimator, reflector, gamma filter and thermal neutrons filter, in front of the initial radiation beam from the source. According to the result of MCNP4C simulation, the Northwest beam tube has the most optimized neuron flux between three north beam tubes of Tehran Research Reactor (TRR). So, it has been chosen for this purpose. Simulation of the BSA has been done in four above mentioned phases. In each stage, ten best configurations of materials with different length and width were selected as the candidates for the next stage. The last BSA configuration includes of: 78 centimeters of air as an empty space, 40 centimeters of Iron plus 52 centimeters of heavy-water as moderator, 30 centimeters of water or 90 centimeters of Aluminum-Oxide as a reflector, 1 millimeters of lithium (Li) as thermal neutrons filter and finally 3 millimeters of Bismuth (Bi) as a filter of gamma radiation. The result of Calculations shows that if we use this BSA configuration for TRR Northwest beam tube, then the best neutron flux and spectrum will be achieved for BNCT. (authors)

  1. Lightweight concrete with enhanced neutron shielding

    Energy Technology Data Exchange (ETDEWEB)

    Brindza, Paul Daniel; Metzger, Bert Clayton

    2016-09-13

    A lightweight concrete containing polyethylene terephthalate in an amount of 20% by total volume. The concrete is enriched with hydrogen and is therefore highly effective at thermalizing neutrons. The concrete can be used independently or as a component of an advanced neutron radiation shielding system.

  2. Neutron radiative capture reactions on nuclei of relevance to 0νββ, dark matter and neutrino/antineutrino searches

    Directory of Open Access Journals (Sweden)

    Tornow W.

    2015-01-01

    Full Text Available A program is underway at the Triangle Universities Nuclear Laboratory (TUNL to measure the neutron capture cross section in the 0.5 to 15 MeV energy range on nuclei whose radioactive daughters could potentially create backgrounds in searches for rare events. Here, we refer to neutrino-less double-beta decay and dark-matter searches, and to detectors built for neutrino and/or antineutrino studies. Neutron capture cross-section data obtained by using the activation method are reported for 40Ar, 74,76Ge, 128,130Te and 136Xe and compared to model calculations and evaluations.

  3. Black Hole - Neutron Star Binary Mergers

    Data.gov (United States)

    National Aeronautics and Space Administration — Gravitational radiation waveforms for black hole-neutron star coalescence calculations. The physical input is Newtonian physics, an ideal gas equation of state with...

  4. Radiation Response of Forward Biased Float Zone and Magnetic Czochralski Silicon Detectors of Different Geometry for 1-MeV Neutron Equivalent Fluence Monitoring

    CERN Document Server

    Mekki, J; Dusseau, Laurent; Roche, Nicolas Jean-Henri; Saigne, Frederic; Mekki, Julien; Glaser, Maurice

    2010-01-01

    Aiming at evaluating new options for radiation monitoring sensors in LHC/SLHC experiments, the radiation responses of FZ and MCz custom made silicon detectors of different geometry have been studied up to about 4 x 10(14) n(eq)/cm(2). The radiation response of the devices under investigation is discussed in terms of material type, thickness and active area influence.

  5. Characterization of Monoenergetic Neutron Reference Fields with a High Resolution Diamond Detector

    CERN Document Server

    Zimbal, A; Nolte, R; Schuhmacher, H

    2009-01-01

    A novel radiation detector based on an artificial single crystal diamond was used to characterize in detail the energy distribution of neutron reference fields at the Physikalisch-Technische Bundesanstalt (PTB) and their contamination with charged particles. The monoenergetic reference fields at PTB in the neutron energy range from 1.5 MeV up to 19 MeV are generated by proton and deuteron beams impinging on solid and gas targets of tritium and deuterium. The energy of the incoming particles and the variation of the angle under which the measurement is performed produce monoenergetic reference fields with different mean energies and line shapes. In this paper we present high resolution neutron spectrometry measurements of different monoenergetic reference fields. The results are compared with calculated spectra taking into account the actual target parameters. Line structures in the order of 80 keV for a neutron energy of 9 MeV were resolved. The shift of the mean energy and the increasing of the width of the ...

  6. Neutron Diagnostic Development for the Z Accelerator

    Science.gov (United States)

    Hahn, Kelly; Chandler, G. A.; Ruiz, C. L.; Jones, B.; Gomez, M. R.; Knapp, P. F.; Sefkow, A. B.; Hansen, S. B.; Schmit, P. F.; Harding, E. C.; Norris, E.; Torres, J. A.; Cooper, G. W.; Styron, J. D.; Frenje, J.; Lahmann, B.; Gatu-Johnson, M.; Seguin, F.; Petrasso, R.; Fittinghoff, D.; May, M.; Snyder, L.; Moy, K.; Buckles, R.; Glebov, V. Yu.

    2016-10-01

    We are studying Magnetized Liner Inertial Fusion (MagLIF) and Gas Puff fusion neutron sources on the Z accelerator. MagLIF experiments have produced up to 3e12 primary DD neutrons with 2-3 keV ion temperatures and 1-2 ns burn widths. Gas puff experiments have produced up to 5e13 primary DD neutrons with higher ion temperatures, longer burn times, and evidence of non-thermonuclear production. For MagLIF, the yield is expected to increase rapidly with increased energy coupling, yet it remains unclear if Gas Puffs would scale as attractively. We review neutron measurements for these experiments and plans for developing neutron diagnostics for these two very different sources. Sandia is sponsored by the U.S. DOE's NNSA under contract DE-AC04-94AL85000.

  7. The accelerator neutron source for boron neutron capture therapy

    Science.gov (United States)

    Kasatov, D.; Koshkarev, A.; Kuznetsov, A.; Makarov, A.; Ostreinov, Yu; Shchudlo, I.; Sorokin, I.; Sycheva, T.; Taskaev, S.; Zaidi, L.

    2016-11-01

    The accelerator based epithermal neutron source for Boron Neutron Capture Therapy (BNCT) is proposed, created and used in the Budker Institute of Nuclear Physics. In 2014, with the support of the Russian Science Foundation created the BNCT laboratory for the purpose to the end of 2016 get the neutron flux, suitable for BNCT. For getting 3 mA 2.3 MeV proton beam, was created a new type accelerator - tandem accelerator with vacuum isolation. On this moment, we have a stationary proton beam with 2.3 MeV and current 1.75 mA. Generation of neutrons is carried out by dropping proton beam on to lithium target as a result of threshold reaction 7Li(p,n)7Be. Established facility is a unique scientific installation. It provides a generating of neutron flux, including a monochromatic energy neutrons, gamma radiation, alpha-particles and positrons, and may be used by other research groups for carrying out scientific researches. The article describes an accelerator neutron source, presents and discusses the result of experiments and declares future plans.

  8. Spin gated GDR widths at moderate temperatures

    Directory of Open Access Journals (Sweden)

    Mukul Ish

    2015-01-01

    Full Text Available We present the evolution of giant dipole resonance (GDR width as a function of angular momentum in the compound nucleus 144Sm in the temperature range of 1.5-2.0 MeV. The high energy γ rays emitted from the decay of excited 144Sm were measured using large NaI detector in coincidence with 4π sum spin spectrometer. GDR widths were found to comply with thermal shape fluctuation model in this temperature range over a wide range of spin. Experimental widths tend to increase rapidly at high angular momentum values.

  9. Some Implications of Neutron Mirror Neutron Oscillation

    CERN Document Server

    Mohapatra, Rabindra N; Nussinov, S

    2005-01-01

    We comment on a recently discussed possibility of oscillations between neutrons and degenerate mirror neutrons in the context of mirror models for particles and forces. It has been noted by Bento and Berezhiani that if these oscillations occurred at a rate of $\\tau^{-1}_{NN'}\\sim sec^{-1}$, it would help explain putative super GKZ cosmic ray events provided the temperature of the mirror radiation is $\\sim 0.3-0.4$ times that of familiar cosmic microwave background radiation. We discuss how such oscillation time scales can be realized in mirror models and find that the simplest nonsupersymmetric model for this idea requires the existence of a low mass (30-3000 GeV) color triplet scalar or vector boson. A supersymmetric model, where this constraint can be avoided is severely constrained by the requirement of maintaining a cooler mirror sector. We also find that the reheat temperature after inflation in generic models that give fast $n-n'$ oscillation be less than about 100 GeV in order to maintain the required ...

  10. Neutron instrumentation for biology

    Energy Technology Data Exchange (ETDEWEB)

    Mason, S.A. [Institut Laue-Langevin, Grenoble (France)

    1994-12-31

    In the October 1994 round of proposals at the ILL, the external biology review sub- committee was asked to allocate neutron beam time to a wide range of experiments, on almost half the total number of scheduled neutron instruments: on 3 diffractometers, on 3 small angle scattering instruments, and on some 6 inelastic scattering spectrometers. In the 3.5 years since the temporary reactor shutdown, the ILL`s management structure has been optimized, budgets and staff have been trimmed, the ILL reactor has been re-built, and many of the instruments up-graded, many powerful (mainly Unix) workstations have been introduced, and the neighboring European Synchrotron Radiation Facility has established itself as the leading synchrotron radiation source and has started its official user program. The ILL reactor remains the world`s most intense dedicated neutron source. In this challenging context, it is of interest to review briefly the park of ILL instruments used to study the structure and energetics of small and large biological systems. A brief summary will be made of each class of experiments actually proposed in the latest ILL proposal round.

  11. Materials for spallation neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Sommer, W.F.; Daemen, L.L. [comps.

    1996-03-01

    The Workshop on Materials for Spallation Neutron Sources at the Los Alamos Neutron Science Center, February 6 to 10, 1995, gathered scientists from Department of Energy national laboratories, other federal institutions, universities, and industry to discuss areas in which work is needed, successful designs and use of materials, and opportunities for further studies. During the first day of the workshop, speakers presented overviews of current spallation neutron sources. During the next 3 days, seven panels allowed speakers to present information on a variety of topics ranging from experimental and theoretical considerations on radiation damage to materials safety issues. An attempt was made to identify specific problems that require attention within the context of spallation neutron sources. This proceedings is a collection of summaries from the overview sessions and the panel presentations.

  12. Eta photoproduction off the neutron at GRAAL

    CERN Document Server

    Kuznetsov, V; Bellini, V; Castoldi, M; D'Angelo, A; Didelez, J P; Salvo, R D; Fantini, A; Franco, D; Gervino, G; Ghio, F; Girolami, B; Giusa, A; Guidal, M; Hourany, E; Kunne, Ronald Alexander; Lapik, A; Levi-Sandri, P; Moricciani, D; Nicoletti, L; Randieri, C; Rudnev, N; Russo, G; Schärf, C; Sperduto, M L; Sutera, M C; Turinge, A

    2005-01-01

    The gamma n -> eta n quasi-free cross section reveals a resonant structure at W ~ 1.675 GeV. This structure may be a manifestation of a baryon resonance. A priori its properties, the possibly narrow width and the strong photocoupling to the neutron, look surprising. This structure may also signal the existence of a narrow state.

  13. LANSCE radiation security system (RSS)

    Energy Technology Data Exchange (ETDEWEB)

    Gallegos, F.R. [Los Alamos National Lab., NM (United States). Los Alamos Neutron Science Center

    1996-12-31

    The Radiation Security System (RSS) is an engineered safety system which automatically terminates transmission of accelerated ion beams in response to pre-defined abnormal conditions. It is one of the four major mechanisms used to protect people from radiation hazards induced by accelerated pulsed ion beams at the Los Alamos Neutron Science Center (LANSCE). The others are shielding, administrative policies and procedures, and qualified, trained personnel. Prompt radiation hazards at the half-mile long LANSCE accelerator exist due to average beam intensities ranging from 1 milli-amp for H{sup +} beam to 100 micro-amps for the high intensity H{sup {minus}} beam. Experimental programs are supplied with variable energy (maximum 800 MeV), pulse-width (maximum 1 msec), and pulse frequency (maximum 120 Hz) ion beams. The RSS includes personnel access control systems, beam spill monitoring systems, and beam current level limiting systems. It is a stand-alone system with redundant logic chains. A fault of the RSS will cause the insertion of fusible beam plugs in the accelerator low energy beam transport. The design philosophy, description, and operation of the RSS are described in this paper.

  14. On the Spectrum Width of Wind Waves

    Institute of Scientific and Technical Information of China (English)

    李陆平; 黄培基

    2001-01-01

    Based on the universal expression of wind wave spectra, four commonly used definitions of the spectrum width arere-examined. The results show that the non-dimensional spectrum width can measure the width of non-dimensionalspectra but it does not reflect the developing state of the spectra. The dimensional spectrum width expresses the degree ofconcentration of wave energy of the spectrum in the process of wind wave growth. Tests show that the spectrum widthpresented by Wen et al. can objectively measure the degree of concentration of wave energy of the spectrum, reflect thestate of wind wave growth, and provides a better result for practical application. The rules for definition of the spectrumwidth are discussed.

  15. Bipartite Graphs of Large Clique-Width

    Science.gov (United States)

    Korpelainen, Nicholas; Lozin, Vadim V.

    Recently, several constructions of bipartite graphs of large clique-width have been discovered in the literature. In the present paper, we propose a general framework for developing such constructions and use it to obtain new results on this topic.

  16. Scintillating Fiber Technology for a High Neutron Spectrometer

    Science.gov (United States)

    Kuznetsov, Evgeny; Adams, James, Jr.; Christl, Mark; Norwood, Joseph; Watts, John

    2014-01-01

    Develop a compact low-power neutron spectrometer that uniquely identifies neutrons in the mixed radiation field expected on crewed deep-space missions. Secondary neutrons are generated by cosmic rays striking heavy crewed spacecraft as well as lunar and planetary surfaces1,2. It has been shown that secondary neutrons can account for up to 50% if the total dose-equivalent received by the crew.

  17. Basic Design of the Cold Neutron Research Facility in HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hark Rho; Lee, K. H.; Kim, Y. K. (and others)

    2005-09-15

    The HANARO Cold Neutron Research Facility (CNRF) Project has been embarked in July 2003. The CNRF project has selected as one of the radiation technology development project by National Science and Technology Committee in June 2002. In this report, the output of the second project year is summarized as a basic design of cold neutron source and related systems, neutron guide, and neutron scattering instruments.

  18. A Comparative Study on the Relationship Between Inter Alar Width, and Inter Commissural Width on Circumferential Arc Width of Maxillary Anterior Teeth in Different Age Groups

    National Research Council Canada - National Science Library

    Kurien, Anjana; Cherian, K P; Mhatre, Shirley; Tharakan, Renji George

    2014-01-01

    This study was done to determine the relationship between interalar width and inter commissural width on circumferential arc width of maxillary anterior teeth in dentulous subjects between the age groups of 20–50 years...

  19. Neutron measurements in ITER using the Radial Neutron Camera

    Science.gov (United States)

    Marocco, D.; Esposito, B.; Moro, F.

    2012-03-01

    The Radial Neutron Camera (RNC) is one of the key diagnostic systems of the ITER international fusion experiment. It is designed to measure the uncollided 14 MeV and 2.5 MeV neutrons from deuterium-tritium (DT) and deuterium-deuterium (DD) fusion reactions taking place in the ITER plasma through an array of 45 detectors positioned along collimated lines of sight. Scintillators and diamonds coupled to fast digital acquisition electronics are among the detectors presently considered for the RNC. The RNC will provide spatially resolved measurements of several plasma parameters needed for fusion power estimation, plasma control and plasma physics studies. The line-integrated RNC neutron fluxes are used to evaluate the local profile of the neutron emission (neutron emissivity, s-1m-3) and therefore the total neutron yield and the birth profile of the alpha particles. The temperature profile of the bulk ions can be derived from the Doppler broadened widths of the RNC line-integrated spectra, that also provide insight on the supra-thermal ions produced by the injection in the plasma of electromagnetic waves and neutral particles. The RNC emissivity and temperature measurements can be employed to estimate the composition of the ITER fuel, namely the ratio between the tritium and deuterium densities. Data processing techniques involving spatial inversion and spectra unfolding are necessary to deduce the profile quantities from the line-integrated RNC measurements. The expected performances of the RNC as a diagnostic for the neutron emissivity/ion temperature/fuel ratio profile (measurement range, time resolution, accuracy, precision) have been estimated by means of synthetic data simulating actual RNC measurements. The results of the simulations, together with an overall description of the diagnostic and of the measurement techniques, are presented.

  20. Neutron detection apparatus and method

    Energy Technology Data Exchange (ETDEWEB)

    Derzon, Mark S.; Borek, III, Theodore T.

    2017-08-15

    An apparatus for neutron detection is provided. The apparatus comprises a sensor medium in electrical contact with an electrode arrangement conformed to collect radiation-generated charge from the sensor medium. The sensor medium comprises a borazine and/or a borazine-based polymer.

  1. Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction

    Science.gov (United States)

    Ikeda, Yoshimasa; Taketani, Atsushi; Takamura, Masato; Sunaga, Hideyuki; Kumagai, Masayoshi; Oba, Yojiro; Otake, Yoshie; Suzuki, Hiroshi

    2016-10-01

    A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by a large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 min. The minimum resolution of the 110 reflection for RANS is approximately 2.5% at 8 μs of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 μs, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time by decreasing a thickness of the moderator or by applying the decoupler system or application of the angular dispersive neutron diffraction technique are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenitic phase in the dual phase mock specimen was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS has been proved to be capable for neutron engineering diffraction aiming for the easy access

  2. A compact plasma focus device and its neutron emission

    Institute of Scientific and Technical Information of China (English)

    王新新; 韩旻; 王志文; 刘坤

    1999-01-01

    A 2.2-kJ compact plasma focus device was developed and its characteristics of neutron emission were investigated. A maximum neutron yield of (3.1 ± 1.5) × 10~7 was obtained at 15 hPa deuterium filling pressure. It was found that the neutron yield Y_n is strongly correlated with the amplitude of the pinch dip in di/dt waveform. The time resolved measurement of the neutron pulse indicated that both the hard X-rays and the neutrons are emitted from plasma focus at the same instant and the width of neutron pulse (FWHM) changes slightly from 50 to 53 ns. The pinch time t_p varies from 1.5 to 16.5 ns and it is usually the case that the shorter t_p, the higher the neutron yield. It was also found that the squirrel cage cathode is better than the tubular cathode.

  3. Sensitivity analysis of the spectra of the core neutronic source in the calculation of radiation damage in internal of PWR reactor vessel. Internal; Analisis de sensibilidad a los espectros de la fuente neutronica del nucleo en el calculo del dano por irradiacion en los internos de la vasija de un reactor PWR

    Energy Technology Data Exchange (ETDEWEB)

    Cadenas Mendicoa, A. M.; Benito Hernandez, M.; Barrerira Pereira, P.

    2012-07-01

    This study is to analyze the sensitivity to the expected differences in the energy spectra characterizing the neutron source that radiates the vessel internals of a commercial PWR reactor, in order to quantify their influence in the quantities that determine the damage in materials metal.

  4. Neutron scattering effects on fusion ion temperature measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Lee (Bechtel/Nevada, Las Vegas, NV); Starner, Jason R.; Cooper, Gary Wayne; Ruiz, Carlos L.; Franklin, James Kenneth (Ktech Corporation, Albuquerque, NM); Casey, Daniel T.

    2006-06-01

    To support the nuclear fusion program at Sandia National Laboratories (SNL), a consistent and verifiable method to determine fusion ion temperatures needs to be developed. Since the fusion temperature directly affects the width in the spread of neutron energies produced, a measurement of the neutron energy width can yield the fusion temperature. Traditionally, the spread in neutron energies is measured by using time-of-flight to convert a spread in neutron energies at the source to a spread in time at detector. One potential obstacle to using this technique at the Z facility at SNL is the need to shield the neutron detectors from the intense bremsstrahlung produced. The shielding consists of eight inches of lead and the concern is that neutrons will scatter in the lead, artificially broaden the neutron pulse width and lead to an erroneous measurement. To address this issue, experiments were performed at the University of Rochester's Laboratory for Laser Energetics, which demonstrated that a reliable ion temperature measurement can be achieved behind eight inches of lead shielding. To further expand upon this finding, Monte Carlo N-Particle eXtended (MCNPX) was used to simulate the experimental geometric conditions and perform the neutron transport. MCNPX was able to confidently estimate results observed at the University of Rochester.

  5. Preliminary Analysis of the Multisphere Neutron Spectrometer

    Science.gov (United States)

    Goldhagen, P.; Kniss, T.; Wilson, J. W.; Singleterry, R. C.; Jones, I. W.; VanSteveninck, W.

    2003-01-01

    Crews working on present-day jet aircraft are a large occupationally exposed group with a relatively high average effective dose from galactic cosmic radiation. Crews of future high-speed commercial aircraft flying at higher altitudes would be even more exposed. To help reduce the significant uncertainties in calculations of such exposures, the Atmospheric Ionizing Radiation (AIR) Project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on five flights of a NASA ER-2 high-altitude aircraft. The primary AIR instrument was a highly sensitive extended-energy multisphere neutron spectrometer with lead and steel shells placed within the moderators of two of its 14 detectors to enhance response at high energies. Detector responses were calculated for neutrons and charged hadrons at energies up to 100 GeV using MCNPX. Neutron spectra were unfolded from the measured count rates using the new MAXED code. We have measured the cosmic-ray neutron spectrum (thermal to greater than 10 GeV), total neutron fluence rate, and neutron effective dose and dose equivalent rates and their dependence on altitude and geomagnetic cutoff. The measured cosmic-ray neutron spectra have almost no thermal neutrons, a large "evaporation" peak near 1 MeV and a second broad peak near 100 MeV which contributes about 69% of the neutron effective dose. At high altitude, geomagnetic latitude has very little effect on the shape of the spectrum, but it is the dominant variable affecting neutron fluence rate, which was 8 times higher at the northernmost measurement location than it was at the southernmost. The shape of the spectrum varied only slightly with altitude from 21 km down to 12 km (56 - 201 grams per square centimeter atmospheric depth), but was significantly different on the ground. In all cases, ambient dose equivalent was greater than effective dose for cosmic-ray neutrons.

  6. Peripheral dose from neutrons and photons in the radiation treatment of pelvic tumors with conventional technique or VMAT. A review; Periphere Neutronen- und Photonendosis bei der Radiotherapie von Tumoren des Beckens mit konventioneller Technik oder VMAT. Eine Literaturuebersicht

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, P. [Medizinische Univ. Graz (Austria). Comprehensive Cancer Center

    2015-07-01

    Peripheral neutron and photon doses from external beam radiation therapy are associated with the risk of carcinogenesis in organs distant to the treated volume. In the irradiation of tumors and target volumes in the pelvis with convention photon-radiotherapy beams with high nominal energies (above 15 MeV) are typically used. During the last years volumetric modulated arc therapy (VMAT) techniques have gained a wide-spread use for pelvic treatments. The beam-energies that are primarily used in VMAT are below 10 MeV. Therefore, a reduction in peripheral dose due to the absence of neutrons can be expected when VMAT is utilized. On the other hand the number of monitor units is increased in increased in VMAT, as compared to conventional unmodulated fields, by a factor of two to three. This leads to an increase in transmission dose from the machine's treatment head, such that the potential benefit might be outbalanced. The question, whether the increasing use of VMAT might lead to a reduction of peripheral dose, is the subject of several studies. Those studies use either measurements in phantom settings or Monte-Carlo simulations. A systematic review of the literature shows diverging, and sometimes even contradictory, findings. Therefore, the issue of peripheral dose and the risk for secondary malignancies requires further investigation. In our opinion, the focus should be put on measurements and simulations, but also on modelling of dose-response correlations.

  7. Neutron Repulsion

    CERN Document Server

    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...

  8. Computational evaluation oa a neutron field facility

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Jose Julio de O.; Pazianotto, Mauricio T., E-mail: jjfilos@hotmail.com, E-mail: mpazianotto@gmail.com [Instituto Tecnologico de Aeronautica (ITA/DCTA), Sao Jose dos Campos, SP (Brazil); Federico, Claudio A.; Passaro, Angelo, E-mail: claudiofederico@ieav.cta.br, E-mail: angelo@ieav.cta.br [Instituto de Estudos Avancados (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil)

    2015-07-01

    This paper describes the results of a study based on computer simulation for a realistic 3D model of Ionizing Radiation Laboratory of the Institute for Advanced Studies (IEAv) using the MCNP5 (Monte Carlo N-Particle) code, in order to guide the installing a neutron generator, produced by reaction {sup 3}H(d,n){sup 4}He. The equipment produces neutrons with energy of 14.1 MeV and 2 x 10{sup 8} n/s production rate in 4 πgeometry, which can also be used for neutron dosimetry studies. This work evaluated the spectra and neutron fluence provided on previously selected positions inside the facility, chosen due to the interest to evaluate the assessment of ambient dose equivalent so that they can be made the necessary adjustments to the installation to be consistent with the guidelines of radiation protection and radiation safety, determined by the standards of National Nuclear Energy Commission (CNEN). (author)

  9. Computational characterization and experimental validation of the thermal neutron source for neutron capture therapy research at the University of Missouri

    Energy Technology Data Exchange (ETDEWEB)

    Broekman, J. D. [University of Missouri, Research Reactor Center, 1513 Research Park Drive, Columbia, MO 65211-3400 (United States); Nigg, D. W. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States); Hawthorne, M. F. [University of Missouri, International Institute of Nano and Molecular Medicine, 1514 Research Park Dr., Columbia, MO 65211-3450 (United States)

    2013-07-01

    Parameter studies, design calculations and neutronic performance measurements have been completed for a new thermal neutron beamline constructed for neutron capture therapy cell and small-animal radiobiology studies at the University of Missouri Research Reactor. The beamline features the use of single-crystal silicon and bismuth sections for neutron filtering and for reduction of incident gamma radiation. The computational models used for the final beam design and performance evaluation are based on coupled discrete-ordinates and Monte Carlo techniques that permit detailed modeling of the neutron transmission properties of the filtering crystals with very few approximations. Validation protocols based on neutron activation spectrometry measurements and rigorous least-square adjustment techniques show that the beam produces a neutron spectrum that has the anticipated level of thermal neutron flux and a somewhat higher than expected, but radio-biologically insignificant, epithermal neutron flux component. (authors)

  10. Gamma-ray width measurements in {sup 15}N at the ELBE nuclear resonance fluorescence setup

    Energy Technology Data Exchange (ETDEWEB)

    Szuecs, Tamas [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); MTA ATOMKI, Debrecen/Hungary (Hungary); Bemmerer, Daniel; Schwengner, Ronald [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Massarczyk, Ralph; Takacs, Marcell; Wagner, Louis [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); TU Dresden (Germany)

    2014-07-01

    The stable nucleus {sup 15}N is the mirror of the astrophysically important {sup 15}O, compound nucleus of the leading reaction of the Bethe-Weizsaecker cycle of hydrogen burning. Most of the {sup 15}N level widths below the neutron and proton emission thresholds are known from just one nuclear resonance fluorescence (NRF) measurement published more than 30 years ago, with unsatisfactory precision on some cases. A recent experiment with the AGATA demonstrator array aimed to determine level widths with the Doppler Shift Attenuation Method (DSAM) in {sup 15}O and {sup 15}N populated in {sup 14}N + {sup 2}H reaction. In order to set a benchmark value for the upcoming AGATA demonstrator data, the widths of several {sup 15}N levels are being studied using the bremsstrahlung facility γELBE at the electron accelerator of Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The γELBE experiment and its preliminary results are presented.

  11. Measurement of Giant Dipole Resonance width at low temperature: A new experimental perspective

    CERN Document Server

    Mukhopadhyay, S; Pal, Surajit; Bhattacharya, Srijit; De, A; Bhattacharya, S; Bhattacharya, C; Banerjee, K; Kundu, S; Rana, T K; Mukherjee, G; Pandey, R; Gohil, M; Pai, H; Meena, J K; Banerjee, S R

    2011-01-01

    The systematic evolution of the giant dipole resonance (GDR) width in the temperature region of 0.9 ~ 1.4 MeV has been measured experimentally for 119Sb using alpha induced fusion reaction and employing the LAMBDA high energy photon spectrometer. The temperatures have been precisely determined by simultaneously extracting the vital level density parameter from the neutron evaporation spectrum and the angular momentum from gamma multiplicity filter using a realistic approach. The systematic trend of the data seems to disagree with the thermal shape fluctuation model (TSFM). The model predicts the gradual increase of GDR width from its ground state value for T > 0 MeV whereas the measured GDR widths appear to remain constant at the ground state value till T ~ 1 MeV and increase thereafter indicating towards a failure of the adiabatic assumption of the model at low temperature.

  12. Fast neutron activation dosimetry with TLDS

    Energy Technology Data Exchange (ETDEWEB)

    Pearson, D.W.; Moran, P.R.

    1975-01-01

    Fast neutron activation using threshold reactions is the only neutron dosimetry method which offers complete discrimination against gamma-rays and preserves some information about the neutron energy. Conventional activation foil technique requires sensitive radiation detectors to count the decay of the neutron induced activity. For extensive measurements at low neutron fluences, vast outlays of counting equipment are required. TL dosimeters are inexpensive, extremely sensitive radiation detectors. The work of Mayhugh et al. (Proc. Third Int. Conf. on Luminescence Dosimetry, Riso Report 249, 1040, (1971)) showed that CaSO/sub 4/: DyTLDs could be used to measure the integrated dose from the decay of the radioactivity produced in the dosimeters by exposure to thermal neutrons. This neatly combines the activation detector and counter functions in one solid state device. This work has been expanded to fast neutron exposures and other TL phosphors. The reactions /sup 19/F(n, 2n)/sup 18/F, /sup 32/S(n,p)/sup 32/P, /sup 24/Mg(n,p)/sup 24/, and /sup 64/Zn(n,p)/sup 64/Cu were found useful for fast neutron activation in commercial TLDs. As each TLD is its own integrating decay particle counter, many activation measurements can be made at the same time. The subsequent readings of the TL signals can be done serially after the induced radioactivity has decayed, using only one TL reader. The neutron detection sensitivity is limited mainly by the number statistics of the neutron activations. The precision of the neutron measurement is within a factor of two of conventional foil activation for comparable mass detectors. Commercially available TLDs can measure neutron fluences of 10/sup 9/n/cm/sup 2/ with 10 percent precision.

  13. Neutron total cross section measurements of gold and tantalum at the nELBE photoneutron source

    CERN Document Server

    Hannaske, Roland; Beyer, Roland; Junghans, Arnd; Bemmerer, Daniel; Birgersson, Evert; Ferrari, Anna; Grosse, Eckart; Kempe, Mathias; Kögler, Toni; Marta, Michele; Massarczyk, Ralph; Matic, Andrija; Schramm, Georg; Schwengner, Ronald; Wagner, Andreas

    2014-01-01

    Neutron total cross sections of 197 Au and nat Ta have been measured at the nELBE photoneutron source in the energy range from 0.1 - 10 MeV with a statistical uncertainty of up to 2 % and a total systematic uncertainty of 1 %. This facility is optimized for the fast neutron energy range and combines an excellent t ime structure of the neutron pulses (electron bunch width 5 ps) with a short flight path of 7 m. Because of the low instantaneous neutron flux transmission measurements of neutron total cross sections are possible, that exhibit very different beam and back ground conditions than found at other neutron sources.

  14. Neutron total cross section measurements of gold and tantalum at the nELBE photoneutron source

    CERN Document Server

    Hannaske, Roland; Beyer, Roland; Junghans, Arnd; Bemmerer, Daniel; Birgersson, Evert; Ferrari, Anna; Grosse, Eckart; Kempe, Mathias; Kögler, Toni; Marta, Michele; Massarczyk, Ralph; Matic, Andrija; Schramm, Georg; Schwengner, Ronald; Wagner, Andreas

    2013-01-01

    Neutron total cross sections of $^{197}$Au and $^\\text{nat}$Ta have been measured at the nELBE photoneutron source in the energy range from 0.1 - 10 MeV with a statistical uncertainty of up to 2 % and a total systematic uncertainty of 1 %. This facility is optimized for the fast neutron energy range and combines an excellent time structure of the neutron pulses (electron bunch width 5 ps) with a short flight path of 7 m. Because of the low instantaneous neutron flux transmission measurements of neutron total cross sections are possible, that exhibit very different beam and background conditions than found at other neutron sources.

  15. Dosimetry methods in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Artuso, E.; Felisi, M.; Regazzoni, V.; Giove, D. [Universita degli Studi di Milano, Department of Physics, Via Festa del Patrono 7, 20122 Milano (Italy); Agosteo, S.; Barcaglioni, L. [Istituto Nazionale di Fisica Nucleare, Milano (Italy); Campi, F.; Garlati, L. [Politecnico di Milano, Energy Department, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); De Errico, F. [Universita degli Studi di Pisa, Department of Civil and Industrial Engineering, Lungamo Pacinotti 43, 56126 Pisa (Italy); Borroni, M.; Carrara, M. [Fondazione IRCCS Istituto Nazionale Tumori, Medical Physics Unit, Via Venezian 1, 20133 Milano (Italy); Burian, J.; Klupak, V.; Viererbl, L.; Marek, M. [Research Centre Rez, Department of Neutron Physics, 250-68 Husinec-Rez (Czech Republic)

    2014-08-15

    Dosimetry studies have been carried out at thermal and epithermal columns of Lvr-15 research reactor for investigating the spatial distribution of gamma dose, fast neutron dose and thermal neutron fluence. Two different dosimetry methods, both based on solid state detectors, have been studied and applied and the accuracy and consistency of the results have been inspected. One method is based on Fricke gel dosimeters that are dilute water solutions and have good tissue equivalence for neutrons and also for all the secondary radiations produced by neutron interactions in tissue or water phantoms. Fricke gel dosimeters give the possibility of separating the various dose contributions, i.e. the gamma dose, the fast neutron dose and the dose due to charged particles generated during thermal neutron reactions by isotopes having high cross section, like 10-B. From this last dose, thermal neutron fluence can be obtained by means of the kerma factor. The second method is based on thermoluminescence dosimeters. In particular, the developed method draw advantage from the different heights of the peaks of the glow curve of such phosphors when irradiated with photons or with thermal neutrons. The results show that satisfactory results can be obtained with simple methods, in spite of the complexity of the subject. However, the more suitable dosimeters and principally their utilization and analysis modalities are different for the various neutron beams, mainly depending on the relative intensities of the three components of the neutron field, in particular are different for thermal and epithermal columns. (Author)

  16. Accelerator and radiation physics

    CERN Document Server

    Basu, Samita; Nandy, Maitreyee

    2013-01-01

    "Accelerator and radiation physics" encompasses radiation shielding design and strategies for hadron therapy accelerators, neutron facilities and laser based accelerators. A fascinating article describes detailed transport theory and its application to radiation transport. Detailed information on planning and design of a very high energy proton accelerator can be obtained from the article on radiological safety of J-PARC. Besides safety for proton accelerators, the book provides information on radiological safety issues for electron synchrotron and prevention and preparedness for radiological emergencies. Different methods for neutron dosimetry including LET based monitoring, time of flight spectrometry, track detectors are documented alongwith newly measured experimental data on radiation interaction with dyes, polymers, bones and other materials. Design of deuteron accelerator, shielding in beam line hutches in synchrotron and 14 MeV neutron generator, various radiation detection methods, their characteriza...

  17. Silicon P.I.N. Junctions used for studies of radiation damage; Etude de l'irradiation aux neutrons rapides du silicium au moyen de jonctions P.I.N

    Energy Technology Data Exchange (ETDEWEB)

    Lanore, J. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-06-01

    Irradiation of silicon P.I.N. junction has been studied primarily for the purpose of developing a radiation damage dosimeter, but also for the purpose of investigating silicon itself. It is known that the rate of recombination of electrons and holes is a linear function of defects introduced by neutron irradiation. Two methods have been used to measure that rate of recombination: forward characteristic measurements, recovery time measurements. In order to explain how these two parameters depend on recombination rate we have given a theory of the P.I.N. junction. We have also given an idea of the carrier lifetime dependence versus temperature. Annealing effects in the range of 70 to 700 K have also been studied, we found five annealing stages with corresponding activation energies. As an application for these studies, we developed a radiation damage dosimeter with which we made several experiments in facilities such as Naiade or Marias. (author) [French] L'irradiation de structures P.I.N. etait faite dans le but d'etudier principalement la mise au point d'un dosimetre a ''radiation damage'' et aussi pour etudier plus profondement le silicium lui-meme. On sait que le taux de recombinaison electrons-trous est une fonction lineaire du taux de defauts introduits par irradiation aux neutrons. Deux methodes ont ete utilisees pour atteindre ce taux de recombinaison: mesures de la caracteristique directe, mesures du temps de retournement. Pour expliquer de quelle facon ces parametres dependent du taux de recombinaison. Nous avons donne une theorie de la jonction P.I.N. Nous avons aussi donne l'allure des variations du temps de vie des porteurs en fonction de la temperature. Nous avons d'autre part effectue des recuits entre 70 et 700 K, domaine dans lequel nous avons trouve cinq etapes de ''guerison'' avec les energies d'activation correspondantes. En application de ces etudes nous avons mis ou point un

  18. From the similarities between neutrons and radon to advanced radon-detection and improved cold fusion neutron-measurements

    Science.gov (United States)

    Tommasino, L.; Espinosa, G.

    2014-07-01

    Neutrons and radon are both ubiquitous in the earth's crust. The neutrons of terrestrial origin are strongly related to radon since they originate mainly from the interactions between the alpha particles from the decays of radioactive-gas (namely Radon and Thoron) and the light nuclei. Since the early studies in the field of neutrons, the radon gas was used to produce neutrons by (α, n) reactions in beryllium. Another important similarity between radon and neutrons is that they can be detected only through the radiations produced respectively by decays or by nuclear reactions. These charged particles from the two distinct nuclear processes are often the same (namely alpha-particles). A typical neutron detector is based on a radiator facing a alpha-particle detector, such as in the case of a neutron film badge. Based on the similarity between neutrons and radon, a film badge for radon has been recently proposed. The radon film badge, in addition to be similar, may be even identical to the neutron film badge. For these reasons, neutron measurements can be easily affected by the presence of unpredictable large radon concentration. In several cold fusion experiments, the CR-39 plastic films (typically used in radon and neutron film-badges), have been the detectors of choice for measuring neutrons. In this paper, attempts will be made to prove that most of these neutron-measurements might have been affected by the presence of large radon concentrations.

  19. Neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Impact of phonon coupling on the radiative nuclear reaction characteristics

    CERN Document Server

    Achakovskiy, Oleg; Kamerdzhiev, Sergei

    2015-01-01

    The pygmy dipole resonance and photon strength functions (PSF) in stable and unstable Ni and Sn isotopes are calculated within the microscopic self-consistent version of the extended theory of finite fermi systems in the quasiparticle time blocking approximation. The approach includes phonon coupling (PC) effects in addition to the standard QRPA approach. The Skyrme force SLy4 is used. A pygmy dipole resonance in 72Ni is predicted at the mean energy of 12.4 MeV exhausting 25.7% of the total energy-weighted sum rule. With our microscopic E1 PSFs in the EMPIRE 3.1 code, the following radiative nuclear reaction characteristics have been calculated for several stable and unstable even-even Sn and Ni isotopes: 1) neutron capture cross sections, 2) corresponding neutron capture gamma-spectra, 3) average radiative widths of neutron resonances. Here, three variants of the microscopic nuclear level density models have been used and a comparison with the phenomenological generalized superfluid model (GSM) has been perf...

  1. Impact of phonon coupling on the radiative nuclear reaction characteristics

    Directory of Open Access Journals (Sweden)

    Achakovskiy Oleg

    2016-01-01

    Full Text Available The pygmy dipole resonance and photon strength functions (PSF in stable and unstable Ni and Sn isotopes are calculated within the microscopic self-consistent version of the extended theory of finite Fermi systems in the quasiparticle time blocking approximation. The approach includes phonon coupling (PC effects in addition to the standard QRPA approach. The Skyrme force SLy4 is used. A pygmy dipole resonance in 72Ni is predicted at the mean energy of 12.4 MeV exhausting 25.7% of the total energy-weighted sum rule. With our microscopic E1 PSFs in the EMPIRE 3.1 code, the following radiative nuclear reaction characteristics have been calculated for several stable and unstable even-even Sn and Ni isotopes: 1 neutron capture cross sections, 2 corresponding neutron capture gamma-spectra, 3 average radiative widths of neutron resonances. Here, three variants of the microscopic nuclear level density models have been used and a comparison with the phenomenological generalized superfluid model has been performed. In all the considered properties, including the recent experimental data for PSF in Sn isotopes, the PC contributions turned out to be significant, as compared with the QRPA one, and necessary to explain the available experimental data.

  2. Neutronics of pulsed spallation neutron sources

    CERN Document Server

    Watanabe, N

    2003-01-01

    Various topics and issues on the neutronics of pulsed spallation neutron sources, mainly for neutron scattering experiments, are reviewed to give a wide circle of readers a better understanding of these sources in order to achieve a high neutronic performance. Starting from what neutrons are needed, what the spallation reaction is and how to produce slow-neutrons more efficiently, the outline of the target and moderator neutronics are explained. Various efforts with some new concepts or ideas have already been devoted to obtaining the highest possible slow-neutron intensity with desired pulse characteristics. This paper also reviews the recent progress of such efforts, mainly focused on moderator neutronics, since moderators are the final devices of a neutron source, which determine the source performance. Various governing parameters for neutron-pulse characteristics such as material issues, geometrical parameters (shape and dimensions), the target-moderator coupling scheme, the ortho-para-hydrogen ratio, po...

  3. Constraints on widths of mixed pentaquark multiplets

    CERN Document Server

    Mohta, V

    2004-01-01

    We determine constraints on the partial widths of mixed pentaquark multiplets in the framework of heavy baryon chiral perturbation theory (HB$\\chi$PT). The partial widths satisfy a GMO-type relation at leading order in HB$\\chi$PT, for arbitrary mixing. The widths of N(1440), N(1710), and $\\Theta(1540)$ are not consistent with ideal mixing, $\\theta_{N} = 35.3^{\\circ}$, but are consistent with $\\theta_{N} \\lesssim 25^{\\circ}$. Furthermore, there are parameter values in HB$\\chi$PT that produce such a mixing angle while allowing the identification of the mass spectrum above. As an alternative to non-ideal mixing, we also suggest reasons for giving up on N(1440) as a pure pentaquark state.

  4. The Variable Line Width of Achernar

    CERN Document Server

    Rivinius, Th; Baade, D; Carciofi, A C; Leister, N; Štefl, S

    2016-01-01

    Spectroscopic observations of Achernar over the past decades, have shown the photospheric line width, as measured by the rotational parameter $v \\sin i$, to vary in correlation with the emission activity. Here we present new observations, covering the most recent activity phase, and further archival data collected from the archives. The $v \\sin i$ variation is confirmed. On the basis of the available data it cannot be decided with certainty whether the increased line width precedes the emission activity, i.e. is a signature of the ejection mechanism, or postdates is, which would make it a signature of re-accretion of some of the disk-material. However, the observed evidence leans towards the re-accretion hypothesis. Two further stars showing the effect of variable line width in correlation with emission activity, namely 66 Oph and $\\pi$ Aqr, are presented as well.

  5. Graph Operations on Clique-Width Bounded Graphs

    OpenAIRE

    Gurski, Frank

    2007-01-01

    Clique-width is a well-known graph parameter. Many NP-hard graph problems admit polynomial-time solutions when restricted to graphs of bounded clique-width. The same holds for NLC-width. In this paper we study the behavior of clique-width and NLC-width under various graph operations and graph transformations. We give upper and lower bounds for the clique-width and NLC-width of the modified graphs in terms of the clique-width and NLC-width of the involved graphs.

  6. Neutron spectrum for neutron capture therapy in boron; Espectro de neutrones para terapia por captura de neutrones en boro

    Energy Technology Data Exchange (ETDEWEB)

    Medina C, D.; Soto B, T. G. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Programa de Doctorado en Ciencias Basicas, 98068 Zacatecas, Zac. (Mexico); Baltazar R, A. [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Programa de Doctorado en Ingenieria y Tecnologia Aplicada, 98068 Zacatecas, Zac. (Mexico); Vega C, H. R., E-mail: dmedina_c@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

    2016-10-15

    Glioblastoma multiforme is the most common and aggressive of brain tumors and is difficult to treat by surgery, chemotherapy or conventional radiation therapy. One treatment alternative is the Neutron Capture Therapy in Boron, which requires a beam modulated in neutron energy and a drug with {sup 10}B able to be fixed in the tumor. When the patients head is exposed to the neutron beam, they are captured by the {sup 10}B and produce a nucleus of {sup 7}Li and an alpha particle whose energy is deposited in the cancer cells causing it to be destroyed without damaging the normal tissue. One of the problems associated with this therapy is to have an epithermal neutrons flux of the order of 10{sup 9} n/cm{sup 2}-sec, whereby irradiation channels of a nuclear research reactor are used. In this work using Monte Carlo methods, the neutron spectra obtained in the radial irradiation channel of the TRIGA Mark III reactor are calculated when inserting filters whose position and thickness have been modified. From the arrangements studied, we found that the Fe-Cd-Al-Cd polyethylene filter yielded a ratio between thermal and epithermal neutron fluxes of 0.006 that exceeded the recommended value (<0.05), and the dose due to the capture gamma rays is lower than the dose obtained with the other arrangements studied. (Author)

  7. Line width of Josephson flux flow oscillators

    DEFF Research Database (Denmark)

    Koshelets, V.P.; Dmitriev, P.N.; Sobolev, A.S.;

    2002-01-01

    to be proven before one initiates real FFO applications. To achieve this goal a comprehensive set of line width measurements of the FFO operating in different regimes has been performed. FFOs with tapered shape have been successfully implemented in order to avoid the superfine resonant structure with voltage...... spacing of about 20 nV and extremely low differential resistance, recently observed in the IVC of the standard rectangular geometry. The obtained results have been compared with existing theories and FFO models in order to understand and possibly eliminate excess noise in the FFO. The intrinsic line width...

  8. Recent Re-Measurement of Neutron and Gamma-Ray Spectra 1080 Meters from the APRD (Army Pulse Radiation Division) Critical Facility,

    Science.gov (United States)

    1984-01-01

    spectres d𔄀missions neutroniques et de rayons gamma. On a compar6 les risultats de ces mesures A plusieurs calculs rcents effectu~s par d’autres...les neutrons et le- rayons gamma; on observe toutefois d’importantes differences spectrales. A - faible altitude, les spectres neutroniques son i6g...measurements were performed by both groups, using a variety of tissue-equivalent ion-chambers, Geiger-M(.ller counters and sulphur activation (n,p). In 1980

  9. Biological effectiveness of neutrons: Research needs

    Energy Technology Data Exchange (ETDEWEB)

    Casarett, G.W.; Braby, L.A.; Broerse, J.J.; Elkind, M.M.; Goodhead, D.T.; Oleinick, N.L.

    1994-02-01

    The goal of this report was to provide a conceptual plan for a research program that would provide a basis for determining more precisely the biological effectiveness of neutron radiation with emphasis on endpoints relevant to the protection of human health. This report presents the findings of the experts for seven particular categories of scientific information on neutron biological effectiveness. Chapter 2 examines the radiobiological mechanisms underlying the assumptions used to estimate human risk from neutrons and other radiations. Chapter 3 discusses the qualitative and quantitative models used to organize and evaluate experimental observations and to provide extrapolations where direct observations cannot be made. Chapter 4 discusses the physical principles governing the interaction of radiation with biological systems and the importance of accurate dosimetry in evaluating radiation risk and reducing the uncertainty in the biological data. Chapter 5 deals with the chemical and molecular changes underlying cellular responses and the LET dependence of these changes. Chapter 6, in turn, discusses those cellular and genetic changes which lead to mutation or neoplastic transformation. Chapters 7 and 8 examine deterministic and stochastic effects, respectively, and the data required for the prediction of such effects at different organizational levels and for the extrapolation from experimental results in animals to risks for man. Gaps and uncertainties in this data are examined relative to data required for establishing radiation protection standards for neutrons and procedures for the effective and safe use of neutron and other high-LET radiation therapy.

  10. Non-Destructive Spent Fuel Characterization with Semi-Conducting Gallium Arsinde Neutron Imaging Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Douglas S. McGregor; Holly K. Gersch; Jeffrey D. Sanders; John C. Lee; Mark D. Hammig; Michael R. Hartman; Yong Hong Yang; Raymond T. Klann; Brian Van Der Elzen; John T. Lindsay; Philip A. Simpson

    2002-01-30

    High resistivity bulk grown GaAs has been used to produce thermal neutron imaging devices for use in neutron radiography and characterizing burnup in spent fuel. The basic scheme utilizes a portable Sb/Be source for monoenergetic (24 keV) neutron radiation source coupled to an Fe filter with a radiation hard B-coated pixellated GaAs detector array as the primary neutron detector. The coated neutron detectors have been tested for efficiency and radiation hardness in order to determine their fitness for the harsh environments imposed by spent fuel. Theoretical and experimental results are presented, showing detector radiation hardness, expected detection efficiency and the spatial resolution from such a scheme. A variety of advanced neutron detector designs have been explored, with experimental results achieving 13% thermal neutron detection efficiency while projecting the possibility of over 30% thermal neutron detection efficiency.

  11. Neutron transport simulation (selected topics)

    Energy Technology Data Exchange (ETDEWEB)

    Vaz, P. [Instituto Tecnologico e Nuclear, Estrada Nacional 10, P-2686-953 Sacavem (Portugal)], E-mail: pedrovaz@itn.pt

    2009-10-15

    Neutron transport simulation is usually performed for criticality, power distribution, activation, scattering, dosimetry and shielding problems, among others. During the last fifteen years, innovative technological applications have been proposed (Accelerator Driven Systems, Energy Amplifiers, Spallation Neutron Sources, etc.), involving the utilization of intermediate energies (hundreds of MeV) and high-intensity (tens of mA) proton accelerators impinging in targets of high Z elements. Additionally, the use of protons, neutrons and light ions for medical applications (hadrontherapy) impose requirements on neutron dosimetry-related quantities (such as kerma factors) for biologically relevant materials, in the energy range starting at several tens of MeV. Shielding and activation related problems associated to the operation of high-energy proton accelerators, emerging space-related applications and aircrew dosimetry-related topics are also fields of intense activity requiring as accurate as possible medium- and high-energy neutron (and other hadrons) transport simulation. These applications impose specific requirements on cross-section data for structural materials, targets, actinides and biologically relevant materials. Emerging nuclear energy systems and next generation nuclear reactors also impose requirements on accurate neutron transport calculations and on cross-section data needs for structural materials, coolants and nuclear fuel materials, aiming at improved safety and detailed thermal-hydraulics and radiation damage studies. In this review paper, the state-of-the-art in the computational tools and methodologies available to perform neutron transport simulation is presented. Proton- and neutron-induced cross-section data needs and requirements are discussed. Hot topics are pinpointed, prospective views are provided and future trends identified.

  12. Neutron transport simulation (selected topics)

    Science.gov (United States)

    Vaz, P.

    2009-10-01

    Neutron transport simulation is usually performed for criticality, power distribution, activation, scattering, dosimetry and shielding problems, among others. During the last fifteen years, innovative technological applications have been proposed (Accelerator Driven Systems, Energy Amplifiers, Spallation Neutron Sources, etc.), involving the utilization of intermediate energies (hundreds of MeV) and high-intensity (tens of mA) proton accelerators impinging in targets of high Z elements. Additionally, the use of protons, neutrons and light ions for medical applications (hadrontherapy) impose requirements on neutron dosimetry-related quantities (such as kerma factors) for biologically relevant materials, in the energy range starting at several tens of MeV. Shielding and activation related problems associated to the operation of high-energy proton accelerators, emerging space-related applications and aircrew dosimetry-related topics are also fields of intense activity requiring as accurate as possible medium- and high-energy neutron (and other hadrons) transport simulation. These applications impose specific requirements on cross-section data for structural materials, targets, actinides and biologically relevant materials. Emerging nuclear energy systems and next generation nuclear reactors also impose requirements on accurate neutron transport calculations and on cross-section data needs for structural materials, coolants and nuclear fuel materials, aiming at improved safety and detailed thermal-hydraulics and radiation damage studies. In this review paper, the state-of-the-art in the computational tools and methodologies available to perform neutron transport simulation is presented. Proton- and neutron-induced cross-section data needs and requirements are discussed. Hot topics are pinpointed, prospective views are provided and future trends identified.

  13. Continuum quasiparticle random phase approximation for astrophysical direct neutron capture reaction of neutron-rich nuclei

    OpenAIRE

    Matsuo, Masayuki

    2014-01-01

    We formulate a many-body theory to calculate the cross section of direct radiative neutron capture reaction by means of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random phase approximation (QRPA). A focus is put on very neutron-rich nuclei and low-energy neutron kinetic energy in the range of O(1 keV) - O(1 MeV), relevant for the rapid neutron-capture process of nucleosynthesis. We begin with the photo-absorption cross section and the E1 strength function, t...

  14. Data acquisition system for the neutron scattering instruments at the intense pulsed neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, R.K.; Daly, R.T.; Haumann, J.R.; Hitterman, R.L.; Morgan, C.B.; Ostrowski, G.E.; Worlton, T.G.

    1981-01-01

    The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a major new user-oriented facility which is now coming on line for basic research in neutron scattering and neutron radiation damage. This paper describes the data-acquisition system which will handle data acquisition and instrument control for the time-of-flight neutron-scattering instruments at IPNS. This discussion covers the scientific and operational requirements for this system, and the system architecture that was chosen to satisfy these requirements. It also provides an overview of the current system implementation including brief descriptions of the hardware and software which have been developed.

  15. A bismuth activation counter for high sensitivity pulsed 14 MeV neutrons

    Science.gov (United States)

    Burns, E. J. T.; Thacher, P. D.; Hassig, G. J.; Decker, R. D.; Romero, J. A.; Barrett, K. P.

    2011-08-01

    We have built a fast neutron bismuth activation counter that measures activation counts from pulsed 14-MeV neutron generators for incident neutron fluences between 30 and 300 neutrons/cm2 at 15.2 cm (6 in.). The activation counter consists of a large bismuth germanate (BGO) detector surrounded by a bismuth metal shield in front of and concentric with the cylindrical detector housing. The 14 MeV neutrons activate the 2.6-millisecond (ms) isomer in the shield and the detector by the reaction 209Bi (n,2nγ) 208mBi. The use of millisecond isomers and activation counting times minimizes the background from other activated materials and the environment. In addition to activation, the bismuth metal shields against other outside radiation sources. We have tested the bismuth activation counter, simultaneously, with two data acquisition systems (DASs) and both give similar results. The two-dimensional (2D) DAS and three dimensional (3D) DAS both consist of pulse height analysis (PHA) systems that can be used to discriminate against gamma radiations below 300 keV photon energy, so that the detector can be used strictly as a counter. If the counting time is restricted to less than 25 ms after the neutron pulse, there are less than 10 counts of background for single pulse operation in all our operational environments tested so far. High-fluence neutron generator operations are restricted by large dead times and pulse height saturation. When we operate our 3D DAS PHA system in list mode acquisition (LIST), real-time corrections to dead time or live time can be made on the scale of 1 ms time windows or dwell times. The live time correction is consistent with nonparalyzable models for dead time of 1.0±0.2 μs for our 3D DAS and 1.5±0.3 μs for our 2D DAS dominated by our fixed time width analog to digital converters (ADCs). With the same solid angle, we have shown that the bismuth activation counter has a factor of 4 increase in sensitivity over our lead activation counter

  16. Neutron radiation embrittlement studies in support of continued operation, and validation by sampling of Magnox reactor steel pressure vessels and components

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R.B.; Bolton, C.J. [Magnox Electric plc, Berkeley Centre, Glos (United Kingdom)

    1997-02-01

    Magnox steel reactor pressure vessels differ significantly from US LWR vessels in terms of the type of steel used, as well as their operating environment (dose level, exposure temperature range, and neutron spectra). The large diameter ferritic steel vessels are constructed from C-Mn steel plates and forgings joined together with manual metal and submerged-arc welds which are stress-relieved. All Magnox vessels are now at least thirty years old and their continued operation is being vigorously pursued. Vessel surveillance and other programmes are summarized which support this objective. The current understanding of the roles of matrix irradiation damage, irradiation-enhanced copper impurity precipitation and intergranular embrittlement effects is described in so far as these influence the form of the embrittlement and hardening trend curves for each material. An update is given on the influence of high temperature exposure, and on the role of differing neutron spectra. Finally, the validation offered by the results of an initial vessel sampling exercise is summarized together with the objectives of a more extensive future sampling programme.

  17. Metal-insulator transition in Si{sub 0.7}Ge{sub 0.3} disordered by fast neutron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhidkov, A.V. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Yadernykh Issledovanij

    1996-10-01

    Both n- and p-type heavily doped and irradiated Si{sub 0.7}Ge{sub 0.3} (N{sub D}, N{sub A}{approx}2.10{sup 26} cm{sup -3}) alloys behaviour was experimentally studied. After irradiation in vertical channels of Kiev WWR-M research reactor with neutron fluence of 10{sup 25} neutron/m{sup 2} (E>1 MeV), the material was determined to be an insulator because of observed Anderson-type metal-insulator transition. There were temperature dependency of specific resistance and Hall effect measurements, which allowed distinct detection of both the {epsilon}{sub 1}-conductivity provided by the thermal activation of carriers from Fermi level to percolation threshold and {epsilon}{sub 3}, where the hopping mechanism dominates. The unusual parameters of hopping process were observed at T<200 K, where this process dominates. The Fermi level value was estimated to be 55 meV relative to the mobility edge; estimated electron state localization radius value is <10 A. (orig.).

  18. Bounding the Higgs boson width through interferometry.

    Science.gov (United States)

    Dixon, Lance J; Li, Ye

    2013-09-13

    We study the change in the diphoton-invariant-mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gg→γγ. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the standard model in the leading-order approximation, which may potentially be experimentally observable. We compute the next-to-leading-order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry." We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV, the mass shift is over 200 MeV and increases with the square root of the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift is much smaller. It might be possible to measure the shift more accurately by exploiting its strong dependence on the Higgs transverse momentum.

  19. Correlation Widths in Quantum--Chaotic Scattering

    OpenAIRE

    Dietz, B.; Richter, A; WeidenmÜller, H.

    2011-01-01

    An important parameter to characterize the scattering matrix S for quantum-chaotic scattering is the width Gamma_{corr} of the S-matrix autocorrelation function. We show that the "Weisskopf estimate" d/(2pi) sum_c T_c (where d is the mean resonance spacing, T_c with 0

  20. Wireline equalization using pulse-width modulation

    NARCIS (Netherlands)

    Schrader, J.H.R.; Klumperink, Eric A.M.; Visschers, J.L.; Nauta, Bram

    2006-01-01

    Abstract-High-speed data links over copper cables can be effectively equalized using pulse-width modulation (PWM) pre-emphasis. This provides an alternative to the usual 2-tap FIR filters. The use of PWM pre-emphasis allows a channel loss at the Nyquist frequency of ~30dB, compared to ~20dB for a

  1. Non destructive testing and neutron radiography in 1994; Les controles non destructifs et la neutronographie en 1994

    Energy Technology Data Exchange (ETDEWEB)

    Bayon, G.

    1994-12-31

    Neutron radiography has been considered for a long time as a promising technique; however it plays a minor part in the world of non destructive testing today, due to the lack of suitable neutron sources and lack of new industrial applications. This paper reviews the present status of neutron sources, neutron radiography activities, especially in France (such as the neutron-capture-issued secondary radiation spectrometry), in nuclear, aerospace, aeronautical and metallurgical sectors, and the last applications of neutron dynamic imaging. 9 refs.

  2. Iodine neutron capture therapy

    Science.gov (United States)

    Ahmed, Kazi Fariduddin

    A new technique, Iodine Neutron Capture Therapy (INCT) is proposed to treat hyperthyroidism in people. Present thyroid therapies, surgical removal and 131I treatment, result in hypothyroidism and, for 131I, involve protracted treatment times and excessive whole-body radiation doses. The new technique involves using a low energy neutron beam to convert a fraction of the natural iodine stored in the thyroid to radioactive 128I, which has a 24-minute half-life and decays by emitting 2.12-MeV beta particles. The beta particles are absorbed in and damage some thyroid tissue cells and consequently reduce the production and release of thyroid hormones to the blood stream. Treatment times and whole-body radiation doses are thus reduced substantially. This dissertation addresses the first of the several steps needed to obtain medical profession acceptance and regulatory approval to implement this therapy. As with other such programs, initial feasibility is established by performing experiments on suitable small mammals. Laboratory rats were used and their thyroids were exposed to the beta particles coming from small encapsulated amounts of 128I. Masses of 89.0 mg reagent-grade elemental iodine crystals have been activated in the ISU AGN-201 reactor to provide 0.033 mBq of 128I. This activity delivers 0.2 Gy to the thyroid gland of 300-g male rats having fresh thyroid tissue masses of ˜20 mg. Larger iodine masses are used to provide greater doses. The activated iodine is encapsulated to form a thin (0.16 cm 2/mg) patch that is then applied directly to the surgically exposed thyroid of an anesthetized rat. Direct neutron irradiation of a rat's thyroid was not possible due to its small size. Direct in-vivo exposure of the thyroid of the rat to the emitted radiation from 128I is allowed to continue for 2.5 hours (6 half-lives). Pre- and post-exposure blood samples are taken to quantify thyroid hormone levels. The serum T4 concentration is measured by radioimmunoassay at

  3. Photon iso-effective dose for cancer treatment with mixed field radiation based on dose-response assessment from human and an animal model: clinical application to boron neutron capture therapy for head and neck cancer.

    Science.gov (United States)

    Gonzalez, Sara Josefina; Pozzi, Emiliano C C; Monti Hughes, Andrea; Provenzano, Lucas; Koivunoro, Hanna; Carando, Daniel Germán; Thorp, Silvia Inés; Casal, Mariana Rosalía; Bortolussi, Silva; Trivillin, Verónica A; Garabalino, Marcela A; Curotto, Paula; Heber, Elisa M; Santa Cruz, Gustavo A; Kankaanranta, Leena; Joensuu, Heikki; Schwint, Amanda E

    2017-08-31

    Boron Neutron Capture Therapy (BNCT) is a treatment modality that combines different radiation qualities. Since the severity of biological damage following irradiation depends on the radiation type, a quantity different from absorbed dose is required to explain effects observed in the clinical BNCT in terms of outcome compared with conventional photon radiation therapy. A new approach for calculating photon iso-effective doses in BNCT was introduced previously. The present work extends this model to include information from dose-response assessments in animal models and humans. Parameters of the model were determined for tumour and precancerous tissue using dose-response curves obtained from BNCT and photon studies performed in the hamster cheek pouch in vivo models of oral cancer and/or pre-cancer, and from head and neck cancer radiotherapy data with photons. To this end, suitable expressions of the dose-limiting Normal Tissue Complication and Tumour Control Probabilities for the reference radiation and for the mixed field BNCT radiation were developed. Pearson's correlation coefficients and p-values showed that TCP and NTCP models agreed with experimental data (with r > 0.87 and p-values >0.57). The photon iso-effective dose model was applied retrospectively to evaluate the dosimetry in tumours and mucosa for head and neck cancer patients treated with BNCT in Finland. Photon iso-effective doses in tumour were lower than those obtained with the standard RBE-weighted model (between 10% to 45%). The results also suggested that the probabilities of tumour control derived from photon iso-effective doses are more adequate to explain the clinical responses than those obtained with the RBE-weighted values. The dosimetry in the mucosa revealed that the photon iso-effective doses were about 30% to 50% higher than the corresponding RBE-weighted values. While the RBE-weighted doses are unable to predict mucosa toxicity, predictions based on the proposed model are

  4. Neutrons, radiation and archaeology: a multi analytical case study of incised rim tradition ceramics in Central Amazon; Neutrons, radiacao e arqueologia: estudo de caso multianalitico de ceramicas da tradicao borda incisa na Amazonia Central

    Energy Technology Data Exchange (ETDEWEB)

    Hazenfratz-Marks, Roberto

    2014-07-01

    This thesis is an interdisciplinary archaeometric study involving archaeological ceramic material from two large archaeological sites in Central Amazon, namely Lago Grande and Osvaldo, on the confluence region of Negro and Solimoes rivers. It was tested a hypothesis about the existence of an exchange network between the former inhabitants of those sites, focusing on material and/or technological exchange. That hypothesis has implications for archaeological theories of human occupation of the pre-colonial Central Amazon, which try to relativise the role of ecological difficulties of the tropical forest as a limiting factor for the emergence of social complexity in the region. The physical-chemical characterization of potsherds and clay samples near the sites was carried out by: instrumental neutron activation analysis (INAA) to determine the elemental chemical composition; electron paramagnetic resonance (EPR) to determine the firing temperature; X-ray diffraction (XRD) to determine the mineralogical composition; and dating by optically stimulated luminescence (OSL). Previous studies showed that Osvaldo and Lago Grande were occupied by people which produced pottery classified in the Manacapuru and Paredao phases, subclasses of the Incised Rim Tradition, around the 5-10th and 7-12th centuries BC, respectively. INAA results were analyzed by multivariate statistical methods, whereby two chemical groups of pottery were defined for each archaeological site. Significant variation in firing temperatures and mineralogical composition were not identified for such groups. By integration of the results with archaeological data, the superposition between pairs of chemical groups was interpreted as a correlate of an ancient exchange network, although it was not possible to define if it existed exclusively between Lago Grande and Osvaldo. On the contrary, it was suggested that Lago Grande participated in a more extensive exchange network by comparison of two chemical groups

  5. Calibration factors for the SNOOPY - NP-100 neutron dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Moscu, D.F. [Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4L8 (Canada)], E-mail: moscudf@mcmaster.ca; McNeill, F.E. [Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, L8S 4L8 (Canada); Chase, J. [Radiation Protection Division, Ontario Power Generation, Whitby, Ontario, L1N 9E3 (Canada)

    2007-10-15

    Within CANDU nuclear power facilities, only a small fraction of workers are exposed to neutron radiation. For these individuals, roughly 4.5% of the total radiation equivalent dose is the result of exposure to neutrons. When this figure is considered across all workers receiving external exposure of any kind, only 0.25% of the total radiation equivalent dose is the result of exposure to neutrons. At many facilities, the NP-100 neutron dosimeter, manufactured by Canberra Industries Incorporated, is employed in both direct and indirect dosimetry methods. Also known as 'SNOOPY', these detectors undergo calibration, which results in a calibration factor relating the neutron count rate to the ambient dose equivalent rate, using a standard Am-Be neutron source. Using measurements presented in a technical note, readings from the dosimeter for six different neutron fields in six source-detector orientations were used, to determine a calibration factor for each of these sources. The calibration factor depends on the neutron energy spectrum and the radiation weighting factor to link neutron fluence to equivalent dose. Although the neutron energy spectra measured in the CANDU workplace are quite different than that of the Am-Be calibration source, the calibration factor remains constant - within acceptable limits - regardless of the neutron source used in the calibration; for the specified calibration orientation and current radiation weighting factors. However, changing the value of the radiation weighting factors would result in changes to the calibration factor. In the event of changes to the radiation weighting factors, it will be necessary to assess whether a change to the calibration process or resulting calibration factor is warranted.

  6. Accurate characterization of weak neutron fields by using a Bayesian approach.

    Science.gov (United States)

    Medkour Ishak-Boushaki, G; Allab, M

    2017-04-01

    A Bayesian analysis of data derived from neutron spectrometric measurements provides the advantage of determining rigorously integral physical quantities characterizing the neutron field and their respective related uncertainties. The first and essential step in a Bayesian approach is the parameterization of the investigated neutron spectrum. The aim of this paper is to investigate the sensitivity of the Bayesian results, mainly the neutron dose H(*)(10) required for radiation protection purposes and its correlated uncertainty, to the selected neutron spectrum parameterization.

  7. Intercomparisons of neutron dosimeters in support of dosimetry measurements in containment

    Energy Technology Data Exchange (ETDEWEB)

    Auman, L.E.; Miller, W.H. (Univ. of Missouri, Columbia (United States)); Graham, C.C.; Stretch, C.D. (Union Electric Co., Fulton, MO (United States)); Welty, T.J.; West, L. (Univ. of Arkansas, Fayetteville (United States))

    1991-01-01

    In support of neutron dosimetry needs at Union Electric's Callaway nuclear plant, an intercomparison of a variety of neutron detection systems was performed. Eight different neutron detection systems were tested in four different neutron fields, utilizing facilities at the Missouri University research reactor (MURR) and the Southwest Radiation Calibration Center at the University of Arkansas. In general, all results agreed within a factor of 2 in predicting the neutron dose equivalent.

  8. Using thermalizers in measuring 'Ukryttia' object's FCM neutron fluxes

    CERN Document Server

    Krasnyanskaya, O G; Odinokin, G I; Pavlovich, V N

    2003-01-01

    The results of research of a thermalizer (heater) width influence on neutron thermalization efficiency during FCM neutron flux measuring in the 'Ukryttia' are described. The calculations of neutron flux densities were performed by the Monte-Carlo method with the help of computer code MCNP-4C for FCM different models.Three possible installations of detectors were considered: on FCM surface,inside the FCM, and inside the concrete under the FCM layer. It was shown,that in order to increase the sensitivity of neutron detectors in intermediate and fast neutrons field,and consequently, to decrease the dependence of the readings of spectral distribution of neutron flux,it is necessary to position the detector inside the so-called thermalizer or heater. The most reasonable application of thick 'heaters' is the situation, when the detector is placed on FCM surface.

  9. DUNBID, the Delft University neutron backscattering imaging detector

    Energy Technology Data Exchange (ETDEWEB)

    Bom, V.R. [Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)]. E-mail: vb@iri.tudelft.nl; Eijk, C.W.E. van [Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Ali, M.A. [Atomic Energy Authority, Nuclear Research Center, Reactor and Neutron Physics Department, P.O. Box 13759, Abu Zabal, Cairo (Egypt)

    2005-12-01

    In the search for low-metallic land mines, the neutron backscattering technique may be applied if the soil is sufficiently dry. An advantage of this method is the speed of detection: the scanning speed may be made comparable to that of a metal detector. A two-dimensional position sensitive detector is tested to obtain an image of the back scattered thermal neutron radiation. Results of experiments using a radionuclide neutron source are presented. The on-mine to no-mine signal ratio can be improved by the application of a window on the neutron time-of-flight. Results using a pulsed neutron generator are also presented.

  10. Polarization in cyclotron radiation in strong magnetic fields

    Institute of Scientific and Technical Information of China (English)

    Luidmila Semionova; Denis Leahy; Jorge Paez

    2010-01-01

    We revisit the problem of radiative transitions of electrons in the presence of a strong magnetic field.We derive fully relativistic cyclotron transition rates for an arbitrary magnetic field,for any orientation of electron spin and for any polarization of the emitted radiation.Also,we obtain the transition rates for any value of the initial electron's parallel momentum.For very strong magnetic fields,transitions to the ground state predominate.Transition rates summed over the electron's spin orientation and for unpolarized radiation are also obtained,which confirm previous results by Latal.Transition widths are calculated for different electron spin orientations and different polarizations of radiation.We obtain general expressions for transition rates that reduce to the results for the non-relativistic case and for unpolarized radiation.Additionally we get,for the non-relativistic approximation,the transition rates for any polarization of radiation.As an application,the first five emission lines are evaluated and compared to the X-ray emitting neutron star V0332+53,which has multiple observable cyclotron lines,taking into account gravitational redshift.The most probable polarization is ∈(2).

  11. Energy and Isotope Dependence of Neutron Multiplicity Distributions

    CERN Document Server

    Lestone, J P

    2014-01-01

    Fission neutron multiplicity distributions are known to be well reproduced by simple Gaussian distributions. Many previous evaluations of multiplicity distributions have adjusted the widths of Gaussian distributions to best fit the measured multiplicity distributions Pn. However, many observables do not depend on the detailed shape of Pn, but depend on the first three factorial moments of the distributions. In the present evaluation, the widths of Gaussians are adjusted to fit the measured 2nd and 3rd factorial moments. The relationships between the first three factorial moments are estimated assuming that the widths of the multiplicity distributions are independent of the initial excitation energy of the fissioning system. These simple calculations are in good agreement with experimental neutron induced fission data up to an incoming neutron energy of 10 MeV.

  12. Neutron reflectometry

    DEFF Research Database (Denmark)

    Klösgen-Buchkremer, Beate Maria

    2014-01-01

    to hundreds of nanometers. Thickness resolution for flat surfaces is in the range of few Ǻngstrøm, and as a peculiar benefit, the presence and properties of buried interfaces are accessible. Focus here will be on neutron reflectometry, a technique that is unique in applications involving composite organic...... of desired information. In the course, an introduction into the method and an overview on selected instruments at large scale facilities will be presented. Examples will be given that illustrate the potential of the method, mostly based on organic films. Results from the investigation of layered films...... and the detection on nanoscopic roughnesses will be shown. The potential of neutron reflectometry is not only of academic origin. It may turn out to be useful in the design and development of new functional materials even though it will never develop into a standard method to be applied in the product control...

  13. Thermal neutron dosimetry using electrochemical etching

    Energy Technology Data Exchange (ETDEWEB)

    Su, S.J.; Sanders, M.E.; Morgan, K.Z.

    1979-07-10

    This study demonstrates the feasibility of using high LET particle radiators to determine the thermal neutron dose by reaction particle registration in low background polycarbonate foils using electrochemical etching. When used in conjunction with the already proven fast neutron recoil particle track registration technique, a viable fast and thermal neutron dosimeter is realized with the advantages of being: non-fading, insensitive to low LET radiation reactions, inexpensive in both processing and materials, useable over a wide dose range, a permanant record and good reproducibility, highly sensitive, and tissue equivalent and a dose equivalent response over a wide range. Most importantly, it finally provides a simple and reliable dosimeter for both the fast and thermal neutron components.

  14. Monte Carlo simulation of neutron scattering instruments

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, P.A.

    1995-12-31

    A library of Monte Carlo subroutines has been developed for the purpose of design of neutron scattering instruments. Using small-angle scattering as an example, the philosophy and structure of the library are described and the programs are used to compare instruments at continuous wave (CW) and long-pulse spallation source (LPSS) neutron facilities. The Monte Carlo results give a count-rate gain of a factor between 2 and 4 using time-of-flight analysis. This is comparable to scaling arguments based on the ratio of wavelength bandwidth to resolution width.

  15. Fusion neutron diagnostics on ITER tokamak

    Science.gov (United States)

    Bertalot, L.; Barnsley, R.; Direz, M. F.; Drevon, J. M.; Encheva, A.; Jakhar, S.; Kashchuk, Y.; Patel, K. M.; Arumugam, A. P.; Udintsev, V.; Walker, C.; Walsh, M.

    2012-04-01

    ITER is an experimental nuclear reactor, aiming to demonstrate the feasibility of nuclear fusion realization in order to use it as a new source of energy. ITER is a plasma device (tokamak type) which will be equipped with a set of plasma diagnostic tools to satisfy three key requirements: machine protection, plasma control and physics studies by measuring about 100 different parameters. ITER diagnostic equipment is integrated in several ports at upper, equatorial and divertor levels as well internally in many vacuum vessel locations. The Diagnostic Systems will be procured from ITER Members (Japan, Russia, India, United States, Japan, Korea and European Union) mainly with the supporting structures in the ports. The various diagnostics will be challenged by high nuclear radiation and electromagnetic fields as well by severe environmental conditions (ultra high vacuum, high thermal loads). Several neutron systems with different sensitivities are foreseen to measure ITER expected neutron emission from 1014 up to almost 1021 n/s. The measurement of total neutron emissivity is performed by means of Neutron Flux Monitors (NFM) installed in diagnostic ports and by Divertor Neutron Flux Monitors (DNFM) plus MicroFission Chambers (MFC) located inside the vacuum vessel. The neutron emission profile is measured with radial and vertical neutron cameras. Spectroscopy is accomplished with spectrometers looking particularly at 2.5 and 14 MeV neutron energy. Neutron Activation System (NAS), with irradiation ends inside the vacuum vessel, provide neutron yield data. A calibration strategy of the neutron diagnostics has been developed foreseeing in situ and cross calibration campaigns. An overview of ITER neutron diagnostic systems and of the associated challenging engineering and integration issues will be reported.

  16. K- nuclear states: Binding energies and widths

    Science.gov (United States)

    Hrtánková, J.; Mareš, J.

    2017-07-01

    K- optical potentials relevant to calculations of K- nuclear quasibound states were developed within several chiral meson-baryon coupled-channels interaction models. The applied models yield quite different K- binding energies and widths. Then the K- multinucleon interactions were incorporated by a phenomenological optical potential fitted recently to kaonic atom data. Though the applied K- interaction models differ significantly in the K-N subthreshold region, our self-consistent calculations of kaonic nuclei across the periodic table lead to conclusions valid quite generally. Due to K- multinucleon absorption in the nuclear medium, the calculated widths of K- nuclear states are sizable, ΓK-≥90 MeV, and exceed substantially their binding energies in all considered nuclei.

  17. Exotic Meson Decay Widths using Lattice QCD

    CERN Document Server

    Cook, M S

    2006-01-01

    A decay width calculation for a hybrid exotic meson h, with JPC=1-+, is presented for the channel h->pi+a1. This quenched lattice QCD simulation employs Luescher's finite box method. Operators coupling to the h and pi+a1 states are used at various levels of smearing and fuzzing, and at four quark masses. Eigenvalues of the corresponding correlation matrices yield energy spectra that determine scattering phase shifts for a discrete set of relative pi+a1 momenta. Although the phase shift data is sparse, fits to a Breit-Wigner model are attempted, resulting in a decay width of about 60 MeV when averaged over two lattice sizes.

  18. Neutron absorbed dose in a pacemaker CMOS

    Energy Technology Data Exchange (ETDEWEB)

    Borja H, C. G.; Guzman G, K. A.; Valero L, C.; Banuelos F, A.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Paredes G, L., E-mail: fermineutron@yahoo.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2012-06-15

    The neutron spectrum and the absorbed dose in a Complementary Metal Oxide Semiconductor (CMOS), has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes an oncology patient that must be treated in a linear accelerator. Pacemaker has integrated circuits as CMOS that are sensitive to intense and pulsed radiation fields. Above 7 MV therapeutic beam is contaminated with photoneutrons that could damage the CMOS. Here, the neutron spectrum and the absorbed dose in a CMOS cell was calculated, also the spectra were calculated in two point-like detectors in the room. Neutron spectrum in the CMOS cell shows a small peak between 0.1 to 1 MeV and a larger peak in the thermal region, joined by epithermal neutrons, same features were observed in the point-like detectors. The absorbed dose in the CMOS was 1.522 x 10{sup -17} Gy per neutron emitted by the source. (Author)

  19. W mass and width at the LHC.

    CERN Document Server

    Malberti, Martina

    2006-01-01

    The precision measurement of the W boson properties, such as its mass and width, constitutes an important consistency check of the Standard Model. This paper, in particular, describes methods to measure the W mass with improved precision at the Large Hadron Collider, exploiting the large number of Z bosons produced. The precision on the W boson mass achievable with an integrated luminosisty of 10~fb^-1 is discussed.

  20. Boron neutron capture therapy (BNCT). Recent aspect, a change from thermal neutron to epithermal neutron beam and a new protocol

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Yoshinobu [Dept. of Neurosurgery National Kagawa Children' s Hospital, Zentsuji, Kagawa (Japan)

    1999-08-01

    Since 1968, One-hundred seventy three patients with glioblastoma (n=81), anaplastic astrocytoma (n=44), low grade astrocytoma (n=16) or other types of tumor (n=32) were treated by boron-neutron capture therapy (BNCT) using a combination of thermal neutron and BSH in 5 reactors (HTR n=13, JRR-3 n=1, MuITR n=98, KUR n=28, JRR-2 n=33). Out of 101 patients with glioma treated by BNCT under the recent protocol, 33 (10 glioblastoma, 14 anaplastic astrocytoma, 9 low grade astrocytoma) patients lived or have lived longer than 3 years. Nine of these 33 lived or have lived longer than 10 years. According to the retrospective analysis, the important factors related to the clinical results were tumor dose radiation dose and maximum radiation dose in thermal brain cortex. The result was not satisfied as it was expected. Then, we decided to introduce mixed beams which contain thermal neutron and epithermal neutron beams. KUR was reconstructed in 1996 and developed to be available to use mixed beams. Following the shutdown of the JRR-2, JRR-4 was renewed for medical use in 1998. Both reactors have capacity to yield thermal neutron beam, epithermal neutron beam and mixed beams. The development of the neutron source lead us to make a new protocol. (author)

  1. Colorimetry and efficiency of white LEDs: Spectral width dependence

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Elaine; Edwards, Paul R.; Martin, Robert W. [Department of Physics, SUPA, Strathclyde University, Glasgow (United Kingdom)

    2012-03-15

    The potential colour rendering capability and efficiency of white LEDs constructed by a combination of individual red, green and blue (RGB) LEDs are analysed. The conventional measurement of colour rendering quality, the colour rendering index (CRI), is used as well as a recently proposed colour quality scale (CQS), designed to overcome some of the limitations of CRI when narrow-band emitters are being studied. The colour rendering performance is maximised by variation of the peak emission wavelength and relative intensity of the component LEDs, with the constraint that the spectral widths follow those measured in actual devices. The highest CRI achieved is 89.5, corresponding to a CQS value of 79, colour temperature of 3800 K and a luminous efficacy of radiation (LER) of 365 lm/W. By allowing the spectral width of the green LED to vary the CRI can be raised to 90.9, giving values of 82.5 and 370 lm/W for the CQS and LER, respectively. The significance of these values are discussed in terms of optimising the possible performance of RGB LEDs. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Are there any good digraph width measures?

    CERN Document Server

    Ganian, Robert; Kneis, Joachim; Meister, Daniel; Obdržálek, Jan; Rossmanith, Peter; Sikdar, Somnath

    2010-01-01

    Several different measures for digraph width have appeared in the last few years. However, none of them shares all the "nice" properties of treewidth: First, being \\emph{algorithmically useful} i.e. admitting polynomial-time algorithms for all $\\MS1$-definable problems on digraphs of bounded width. And, second, having nice \\emph{structural properties} i.e. being monotone under taking subdigraphs and some form of arc contractions. As for the former, (undirected) $\\MS1$ seems to be the least common denominator of all reasonably expressive logical languages on digraphs that can speak about the edge/arc relation on the vertex set.The latter property is a necessary condition for a width measure to be characterizable by some version of the cops-and-robber game characterizing the ordinary treewidth. Our main result is that \\emph{any reasonable} algorithmically useful and structurally nice digraph measure cannot be substantially different from the treewidth of the underlying undirected graph. Moreover, we introduce \\...

  3. Relative biological effectiveness and tolerance dose of fission neutrons in canine skin for a potential combination of neutron capture therapy and fast-neutron therapy.

    Science.gov (United States)

    Kadosawa, Tsuyoshi; Ohashi, Fumihito; Nishimura, Ryohei; Sasaki, Nobuo; Saito, Isao; Wakabayashi, Hiroaki; Takeuchi, Akira

    2003-10-01

    To investigate the potential efficacy of fission neutrons from a fast-neutron reactor for the treatment of radioresistant tumors, the relative biological effectiveness (RBE) and tolerance dose of fission neutrons in canine skin were determined. The forelimbs of 34 healthy mongrel dogs received a single dose of fission neutrons (5.6, 6.8, 8.2, 9.6 or 11 Gy) or 137Cs gamma rays (10, 15, 20, 25 or 30 Gy). Based on observations of radiodermatitis for each radiation, the single-fraction RBE of fission neutrons in the sixth month was calculated as approximately 3. The tolerance doses of fission neutrons and gamma rays, defined as the highest doses giving no moist desquamation on the irradiated skin in the recovery phase, were estimated as 7.6 Gy and 20 Gy, respectively. The tolerance dose of 7.6 Gy of fission neutrons included 5.0 Gy of fast neutrons possessing high anti-tumor effects and 1.4 x 10(12) n/cm2 of thermal neutrons, which could be applicable to neutron capture therapy (NCT). The combination of fast-neutron therapy and NCT using a fast-neutron reactor might be useful for the treatment of radioresistant tumors.

  4. Microscopic calculations of the characteristics of radiative nuclear reactions for double-magic nuclei

    CERN Document Server

    Achakovskiy, Oleg; Tselyaev, Victor; Shitov, Mikhail

    2015-01-01

    The neutron capture cross sections and average radiative widths of neutron resonances for two double-magic nuclei 132Sn and 208Pb have been calculated using the microscopic photon strength functions, which were obtained within the microscopic self-consistent version of the extended theory of finite Fermi systems in the time blocking approximation. For the first time, the microscopic PSFs have been obtained within the fully self-consistent approach with exact accounting for the single particle continuum (for 208Pb). The approach includes phonon coupling effects in addition to the standard RPA approach. The known Skyrme force has been used. The calculations of nuclear reaction characteristics have been performed with the EMPIRE 3.1 nuclear reaction code. Here, three nuclear level density (NLD) models have been used: the so-called phenomenological GSM, the EMPIRE specific (or Enhanced GSM) and the microscopical combinatorial HFB NLD models. For both considered characteristics we found a significant disagreement ...

  5. In the wonderland of ultra-parallel neutron beams

    Indian Academy of Sciences (India)

    Appoorva G Wagh

    2008-10-01

    Bragg reflections from single crystals yield angular widths of a few arcsec for thermal neutron beams. The Bonse-Hart proposal to attain a sharp, nearly rectangular profile by Bragg reflecting neutrons multiply from a channel-cut single crystal, was realized in its totality three and a half decades later by achieving the corresponding Darwin reflection curves for 5.23 Å neutrons. This facilitated SUSANS (Super USANS) measurements in the ∼ 10-5 Å-1 range. The polarized neutron option was introduced into the SUSANS set-up by separating the up- and down-spin neutron beams by ∼ 10 arcsec with a magnetic (air) prism. The neutron angular width has recently been reduced further by an order of magnitude to ∼ 0.6 arcsec by diffracting 5.3 Å neutrons from a judiciously optimized Bragg prism. This constitutes the most parallel monochromatic neutron beam produced to date. I present the first SUSANS spectra probing the ∼ 10-6 Å-1 domain, recorded with this beam.

  6. Spallation Neutron Source (SNS)

    Data.gov (United States)

    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...

  7. Halo Effect on Direct Neutron Capture Process

    Institute of Scientific and Technical Information of China (English)

    刘祖华; 周宏余

    2004-01-01

    We calculate the capture cross sections of the 10Be(n,γ) 11 Be reaction by means of the asymptotic normalization coefficient method and demonstrate the halo effects on the capture cross sections for the direct radiative neutron capture where a p-, s- or d-wave neutron is captured into an s-orbit or p-orbit in 11 Be by emitting an E1 γ-ray,respectively. The result shows that the enormous enhancement of the capture cross section is just due to the large overlap of the incident neutron wave with the extended tail of the halo, which is clearly illustrated by the reduced transition amplitude function.

  8. Development of DUPIC safeguards neutron counter

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Gil; Cha, Hong Ryul; Kim, Ho Dong; Hong, Jong Sook; Kang, Hee Young

    1999-08-01

    KAERI, in cooperation with LANL, developed DSNC (DUPIC Safeguards Neutron Counter) for safeguards implementing on DUPIC process which is under development by KAERI for direct use of spent PWR fuel in CANDU reactors. DSNC is a well-type neutron coincidence counter with substantial shielding to protect system from high gamma radiation of spent fuel. General development procedures in terms of design, manufacturing, fabrication, cold and hot test, performance test for DSNC authentication by KAERI-IAEA-LANL are described in this report. It is expected that the techniques related DSNC development and associated neutron detection and evaluation method could be applied for safeguards improvement. (Author). 20 refs., 16 tabs. 98 figs.

  9. Development of DUPIC safeguards neutron counter

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Gil; Cha, Hong Ryul; Kim, Ho Dong; Hong, Jong Sook; Kang, Hee Young

    1999-08-01

    KAERI, in cooperation with LANL, developed DSNC (DUPIC Safeguards Neutron Counter) for safeguards implementing on DUPIC process which is under development by KAERI for direct use of spent PWR fuel in CANDU reactors. DSNC is a well-type neutron coincidence counter with substantial shielding to protect system from high gamma radiation of spent fuel. General development procedures in terms of design, manufacturing, fabrication, cold and hot test, performance test for DSNC authentication by KAERI-IAEA-LANL are described in this report. It is expected that the techniques related DSNC development and associated neutron detection and evaluation method could be applied for safeguards improvement. (Author). 20 refs., 16 tabs. 98 figs.

  10. Neutron Damage and MAX Phase Ternary Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Barsoum, Michael [Drexel Univ., Philadelphia, PA (United States); Hoffman, Elizabeth [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Sindelar, Robert [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Garcua-Duaz, Brenda [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Kohse, Gordon [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2014-06-17

    The Demands of Gen IV nuclear power plants for long service life under neutron radiation at high temperature are severe. Advanced materials that would withstand high temperatures (up to 1000+ C) to high doses in a neutron field would be ideal for reactor internal structures and would add to the long service life and reliability of the reactors. The objective of this work is to investigate the response of a new class of machinable, conductive, layered, ternary transition metal carbides and nitrides - the so-called MAX phases - to low and moderate neutron dose levels.

  11. Neutron scattering. Lectures

    Energy Technology Data Exchange (ETDEWEB)

    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)

  12. Neutron Therapy Facility

    Data.gov (United States)

    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)...

  13. On the use of Indium ({sup 115}In) activation foils for the study of neutron radiation field surrounding a not shielded cyclotron; Sobre o uso de folhas de ativacao de Indio ({sup 115}In) para o estudo do campo de radiacao neutronica ao redor de um ciclotron nao blindado

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Adriana, E-mail: amgr@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Programa de Pos-Graduacao em Ciencia e Tecnologia das Radiacoes, Minerais e Materiais; Rodrigues, Sergio Luiz Moreira; Andrade, Ricardo Severino [Centro de Desenvolvimento da Tecnologia Nuclear (SECPRA/CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Servico de Pesquisa e Producao de Radiofarmacos; Lacerda, Marco Aurelio de Sousa [Centro de Desenvolvimento da Tecnologia Nuclear (SEPRA/CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Servico de Protecao Radiologica; Silva, Teogenes Augusto da [Centro de Desenvolvimento da Tecnologia Nuclear (SERAS/CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Servico das Radiacoes Aplicadas a Saude

    2011-10-26

    Use activation foils of {sup 115}In were evaluated for study of neutron radiation field surrounding a non shielded 16.5 MeV cyclotron, during the production of fluorine-18. Two foils of {sup 115}In were used which were exposed to the neutron flux of target-chamber of the GEPETtrace-8 of CDTN/CNEN, Brazil. The first foil were positioned in front of cyclotron beam, and the second one in the diametral opposed position to the beam. It was possible to distinguish for the first foil the 417 keV photo peaks, attributed to the thermal and the 417 keV neutrons attributed to the fast neutrons. On the second foil it was only distinguished the 417 keV photopeak. The results had shown that it is possible to evaluate the fast and thermal neutron fraction surrounding the cyclotron by using indium foils. However, the short half life of the {sup 115}In makes unviable the simultaneous irradiation of a great number of foils

  14. A Tailorable Structural Composite for GCR and Albedo Neutron Protection on the Lunar Surface Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A tailorable structural composite that will provide protection from the lunar radiation environment, including GCR and albedo neutrons will be developed. This...

  15. Enhanced multifunctional paint for detection of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, Joseph C.; Moses, Edward Ira; Rubenchik, Alexander M.

    2017-03-07

    An enhanced multifunctional paint apparatus, systems, and methods for detecting radiation on a surface include providing scintillation particles; providing an enhance neutron absorptive material; providing a binder; combining the scintillation particles, the enhance neutron absorptive material, and the binder creating a multifunctional paint; applying the multifunctional paint to the surface; and monitoring the surface for detecting radiation.

  16. WAVS radiation shielding references and assumptions

    Energy Technology Data Exchange (ETDEWEB)

    McLean, Adam [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-07

    At ITER, the confluence of a high radiation environment and the requirement for high performance imaging for plasma and plasma-facing surface diagnosis will necessitate extensive application of radiation shielding. Recommended here is a dual-layer shield design composed of lead for gamma attenuation, surrounded by a fire-resistant polyehtylene doped with a thermal neutron absorber for neutron shielding.

  17. Characterization methods for an accelerator based fast-neutron facility

    Science.gov (United States)

    Franklyn, C.; Daniels, G. C.

    2012-02-01

    A fast neutron facility provides a number of complexities in both detection and shielding, the latter arising not only due to uncertainty in the behaviour of the scattered radiation (neutron and gamma-rays) from a fast neutron source, but also on shielding requirements that have to take into account internal and external factors, such as dose limitations, space availability for implementing bulky shielding and secondary interactions of the radiation with materials. This has possible influence on experimental measurements with a low signal to noise ratio. This paper reports on some of the investigations performed at a RFQ accelerator facility generating > 1011 neutrons per second with energies up to 14 MeV, which are used to perform fast neutron radiography studies. Areas highlighted are the neutron cross section libraries, where important data needs to be reviewed or updated.

  18. Neutron Capture Reactions on lu Isotopes at Dance

    Science.gov (United States)

    Roig, O.; Meot, V.; Daugas, J.-M.; Morel, P.; Jandel, M.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Keksis, A. L.; Rundberg, R. S.; Ullmann, J. L.; Wouters, J. M.

    2013-03-01

    The DANCE1 (Detector for Advanced Neutron Capture Experiments) array at LANSCE spallation neutron source in Los Alamos has been used to obtain the neutron radiative capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process.2,3 Three targets were used to perform these measurements. One was natural Lu foil of 31 mg/cm2 and the other two were isotope-enriched targets of 175Lu and 176Lu. Firstly, the cross sections were obtained by normalizing yield to a well-known cross section at the thermal neutron energy. Now, we want to obtain absolute cross sections of radiative capture through a precise neutron flux determination, an accurate target mass measurement and an efficiency determination of the DANCE array.

  19. Point Scattered Function (PScF) for fast neutron radiography

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Mohamed H. [Nuclear and Radiation Engineering Department, Alexandria University, Alexandria 21544 (Egypt)], E-mail: mhmheg@yahoo.com

    2009-08-01

    Fast neutron radiography opened up a new range of possibilities to image extremely dense objects. The removal of the scattering effect is one of the most challenging problems in neutron imaging. Neutron scattering in fast neutron radiography did not receive much attention compared with X-ray and thermal neutron radiography. The purpose of this work is to investigate the behavior of the Point Scattered Function (PScF) as applied in fast neutron radiography. The PScF was calculated using MCNP as a spatial distribution of scattered neutrons over the detector surface for one emitting source element. Armament and explosives materials, namely, Rifle steel, brass, aluminum and trinitrotoluene (TNT) were simulated. Effect of various sample thickness and sample-to-detector distance were considered. Simulated sample geometries included a slab with varying thickness, a sphere with varying radii, and a cylinder with varying base radii. Different neutron sources, namely, Cf-252, DT as well as DD neutron sources were considered. Neutron beams with zero degree divergence angle; and beams with varying angles related to the normal to the source plane were simulated. Curve fitting of the obtained PScF, in the form of Gaussian function, were given to be used in future work using image restoration codes. Analytical representation of the height as well as the Full Width at Half Maximum (FWHM) of the obtained Gaussian functions eliminates the need to calculate the PScF for sample parameters that were not investigated in this study.

  20. Neutron-based sterilization of anthrax contamination.

    Science.gov (United States)

    Liu, Bin; Wang, Qingfei

    2006-05-01

    With the anthrax threat becoming a reality, it is very important to have an effective way to sterilize areas contaminated by anthrax. Anthrax spores are the dormant form of the anthrax bacteria. They can germinate in tissues, producing new bacteria that release lethal toxins. Neutrons can be a powerful tool in our defense against anthrax contamination. Neutrons are elementary particles that have no charge, which allows them to be very penetrating, killing the anthrax spores on the surface and inside the containers. So neutrons have an advantage over other forms of radiation if deep penetration is required to kill biological organisms. A Cf neutron source allows for a low cost method of decontamination. It emits most neutrons in the 100 keV to 2 MeV energy regions, and a neutron in this energy region is 20 times more deadly than electrons or gamma rays in killing anthrax spores. If we just consider the first neutron collision with anthrax spores and that all the anthrax spores will not survive at the dose level above 2.0 x 10 Gy, our calculations show that a 0.5-g Cf neutron source within 20 min can generate 1.11 x 10 m fluence neutrons, which is good enough to kill the anthrax spores on the sample. An experimental confirmation of the above results may prove that to achieve 1.11 x 10 m fluence neutrons on the anthrax spore sample, the neutron irradiation time may be reduced dramatically or the Cf neutron source reduced to 0.1 g level or even less. The aim of this paper is to evaluate a feasible way to sterilize the anthrax contamination by using a Cf neutron source. Presently, we are mainly concentrating on the theoretical estimation of neutron fluence to see if the Cf neutron source can deliver enough neutron irradiation dose to kill the anthrax spores. Our future work will focus on experimental confirmation and Monte Carlo simulation by using Geant4 or MCNP codes. At that time, we will consider the effects of the real experimental setup, the shielding materials