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Sample records for based epithermal neutron

  1. Pulsed neutron sources for epithermal neutrons

    International Nuclear Information System (INIS)

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

  2. An accelerator-based epithermal photoneutron source for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 107 neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF3 composite and a stacked Al/Teflon design) at various incident electron energies

  3. An accelerator-based epithermal photoneutron source for boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, H.E.

    1996-04-01

    Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 10{sup 7} neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF{sub 3} composite and a stacked Al/Teflon design) at various incident electron energies.

  4. Production of epithermal neutron beams for BNCT

    CERN Document Server

    Bisceglie, E; Colonna, N; Paticchio, V; Santorelli, P; Variale, V

    2002-01-01

    The use of boron neutron capture therapy (BNCT) for the treatment of deep-seated tumors requires neutron beams of suitable energy and intensity. Simulations indicate the optimal energy to reside in the epithermal region, in particular between 1 and 10 keV. Therapeutic neutron beams with high spectral purity in this energy range could be produced with accelerator-based neutron sources through a suitable neutron-producing reaction. Herein, we report on different solutions that have been investigated as possible sources of epithermal neutron beams for BNCT. The potential use of such sources for a hospital-based therapeutic facility is discussed.

  5. The Fission Converter-Based Epithermal Neutron Irradiation Facility at the Massachusetts Institute of Technology Reactor

    International Nuclear Information System (INIS)

    A new type of epithermal neutron irradiation facility for use in neutron capture therapy has been designed, constructed, and put into operation at the Massachusetts Institute of Technology Research Reactor (MITR). A fission converter, using plate-type fuel and driven by the MITR, is used as the source of neutrons. After partial moderation and filtration of the fission neutrons, a high-intensity forward directed beam is available with epithermal neutron flux [approximately equal to]1010 n/cm2.s, 1 eV ≤ E ≤ 10 keV, at the entrance to the medical irradiation room, and epithermal neutron flux = 3 to 5 x 109 n/cm2.s at the end of the patient collimator. This is currently the highest-intensity epithermal neutron beam. Furthermore, the system is designed and licensed to operate at three times higher power and flux should this be desired. Beam contamination from unwanted fast neutrons and gamma rays in the aluminum, polytetrafluoroethylene, cadmium and lead-filtered beam is negligible with a specific fast neutron and gamma dose, Dγ,fn/φepi [less than or approximately equal] 2 x 10-13 Gy cm2/nepi. With a currently approved neutron capture compound, boronophenylalanine, the therapeutically advantageous depth of penetration is >9 cm for a unilateral beam placement. Single fraction irradiations to tolerance can be completed in 5 to 10 min. An irradiation control system based on beam monitors and redundant, high-reliability programmable logic controllers is used to control the three beam shutters and to ensure that the prescribed neutron fluence is accurately delivered to the patient. A patient collimator with variable beam sizes facilitates patient irradiations in any desired orientation. A shielded medical room with a large window provides direct viewing of the patient, as well as remote viewing by television. Rapid access through a shielded and automatically operated door is provided. The D2O cooling system for the fuel has been conservatively designed with excess

  6. Temperature imaging using epithermal neutrons

    International Nuclear Information System (INIS)

    The paper concerns the temperature measurement of suitable targets, both remotely and non-invasively, using epithermal neutrons. The text was presented at the Neutron Resonance Radiography Workshop, Los Alamos, U.S.A., 1987. The technique is demonstrated for tantalum foils at different temperatures, using a pulsed beam of epithermal neutrons, at both Los Alamos and ISIS (United Kingdom). Results on the measured time-of-flight spectra and the tantalum resonances are presented. Beam properties and fluxes at ISIS are discussed. Features of the proposed detectors suitable for the temperature technique are outlined, along with the data analysis, the moving targets, the cyclic temperature variations and transients, and the usefulness of the technique. (U.K.)

  7. The time-of-flight epithermal neutron spectrum measurement from accelerator based BNCT facility

    International Nuclear Information System (INIS)

    Results of epithermal neutrons spectrum measurement by time-of-flight method for different beam shaping assembly designed for BNCT purposes are presented. Discuss method to realize time-of-flight measurement at accelerator. Results looks are important for beam shaping assembly optimization and accurate and reliable treatment planning. (author)

  8. A method for moisture measurement in porous media based on epithermal neutron scattering.

    Science.gov (United States)

    El Abd, A

    2015-11-01

    A method for moisture measurement in porous media was proposed. A wide beam of epithermal neutrons was obtained from a Pu-Be neutron source immersed in a cylinder made of paraffin wax. (3)He detectors (four or six) arranged in the backward direction of the incident beam were used to record scattered neutrons from investigated samples. Experiments of water absorption into clay and silicate bricks, and a sand column were investigated by neutron scattering. While the samples were absorbing water, scattered neutrons were recorded from fixed positions along the water flow direction. It was observed that, at these positions scattered neutrons increase as the water uptake increases. Obtained results are discussed in terms of the theory of macroscopic flow in porous media. It was shown that, the water absorption processes were Fickian and non Fickian in the sand column and brick samples, respectively. The advantages of applying the proposed method to study fast as well as slow flow processes in porous media are discussed. PMID:26298060

  9. Shielding design of a treatment room for an accelerator-based epithermal neutron irradiation facility for BNCT

    International Nuclear Information System (INIS)

    Protecting the facility personnel and the general public from radiation exposure is a primary safety concern of an accelerator-based epithermal neutron irradiation facility. This work makes an attempt at answering the questions open-quotes How much?close quotes and open-quotes What kind?close quotes of shielding will meet the occupational limits of such a facility. Shielding effectiveness is compared for ordinary and barytes concretes in combination with and without borated polyethylene. A calculational model was developed of a treatment room, patient open-quotes scatterer,close quotes and the epithermal neutron beam. The Monte Carlo code, MCNP, was used to compute the total effective dose equivalent rates at specific points of interest outside of the treatment room. A conservative occupational effective dose rate limit of 0.01 mSv h-1 was the guideline for this study. Conservative Monte Carlo calculations show that constructing the treatment room walls with 1.5 m of ordinary concrete, 1.2 m of barytes concrete, 1.0 m of ordinary concrete preceded by 10 cm of 5% boron-polyethylene, or 0.8 m of barytes concrete preceded by 10 cm of 5% boron-polyethylene will adequately protect facility personnel. 20 refs., 8 figs., 2 tabs

  10. Epithermal neutron activation analysis of food

    International Nuclear Information System (INIS)

    Food samples were irradiated with thermal and epithermal neutrons. The average ratios of thermal to epithermal activity were determined for 80Br, 49Ca, 38Cl, 60mCo, 42K, 27Mg, 56Mn, 24Na, and 86mRb. They were equal to 2.1, 26, 24, 6.6, 19, 16, 11, 23 and 1.9, respectively. Then, 57 food samples were analyzed by epithermal neutron activation analysis for Br and Rb. The concentrations (in ppm) of Br and Rb were in asparagus (2) 2.3, 11.5; beets (3) 0.5, 0.8; beef (3) 1.7, 3.6; cabbage (5) 0.5, 10.8; carrot (3) 0.2, 3.7; chicken (3) 0.6, 4.4; chocolate (7) 11.1, 18.7; egg (3) 0.9, 1.9; french bean (3) 0.3, 1.0; goose (2) 1.3, 9.3; lettuce (2) 0.9, 1.7; pork (1) 1.5, 4.4; potato (7) 1.0, 1.2; sausage (3) 4.8, 3.5; spinach (3) 3.6, 4.0; strawberry jam (3) 0.4, 1.4; tomato (1) 13.5, 14.6; turkey (3) 1.2, 4.9. respectively. The number of samples and analyzed is indicated in parentheses. (author)

  11. An accelerator-based epithermal photoneutron source for BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Nigg, D.W.; Mitchell, H.E.; Harker, Y.D.; Yoon, W.Y. [and others

    1995-11-01

    Therapeutically-useful epithermal-neutron beams for BNCT are currently generated by nuclear reactors. Various accelerator-based neutron sources for BNCT have been proposed and some low intensity prototypes of such sources, generally featuring the use of proton beams and beryllium or lithium targets have been constructed. This paper describes an alternate approach to the realization of a clinically useful accelerator-based source of epithermal neutrons for BNCT that reconciles the often conflicting objectives of target cooling, neutron beam intensity, and neutron beam spectral purity via a two stage photoneutron production process.

  12. Towards epithermal boron neutron capture therapy for cancer

    International Nuclear Information System (INIS)

    Progress in the treatment of local disseminating cancer such as high grade brain tumours is poor, and the ability to kill individual cancer cells in the midst of normal cells has not been achieved. Binary therapies hold the most promise of this, and of these Boron Neutron Capture Therapy (BNCT) is the most advanced. Epithermal neutron beams are essential for outpatient treatment of high grade brain tumours and these are now installed and being characterised in Europe and the USA, and are at the design stage in Australia. These beams would allow the bilateral irradiation of the entire brain, and as such are ideally suited for the prophylactic therapy of subclinical metastases. When coupled with appropriate cancer affined boron compounds, therapeutic ratios of 2-3 should be achieved. At present the only source of an epithermal neutron beam is a nuclear reactor. The Euratom reactor at Petten and the Brookhaven Medical Reactor have been retrofitted with filters to produced an epithermal neutron beam. These beams have been characterised and used in dose escalation studies with dogs to study normal tissue tolerance using borocaptate (BSH). Another beam is available at the MIT medical research reactor. Clinical trails at Petten for glioblastoma with BSH and at MIT using boronophenylalanine for melanoma metastases to the extremities are expected to commence this year. The state of the art of reactor based BNCT is reviewed and the potential for a major change in the prognosis of local control of disseminating cancer is explored. 29 refs.,

  13. Simulation study of accelerator based quasi-mono-energetic epithermal neutron beams for BNCT.

    Science.gov (United States)

    Adib, M; Habib, N; Bashter, I I; El-Mesiry, M S; Mansy, M S

    2016-01-01

    Filtered neutron techniques were applied to produce quasi-mono-energetic neutron beams in the energy range of 1.5-7.5 keV at the accelerator port using the generated neutron spectrum from a Li (p, n) Be reaction. A simulation study was performed to characterize the filter components and transmitted beam lines. The feature of the filtered beams is detailed in terms of optimal thickness of the primary and additive components. A computer code named "QMNB-AS" was developed to carry out the required calculations. The filtered neutron beams had high purity and intensity with low contamination from the accompanying thermal, fast neutrons and γ-rays. PMID:26474209

  14. Epithermal neutron activation analysis in applied microbiology

    International Nuclear Information System (INIS)

    Some results from applying epithermal neutron activation analysis at FLNP JINR, Dubna, Russia, in medical biotechnology, environmental biotechnology and industrial biotechnology are reviewed. In the biomedical experiments biomass from the blue-green alga Spirulina platensis (S. platensis) has been used as a matrix for the development of pharmaceutical substances containing such essential trace elements as selenium, chromium and iodine. The feasibility of target-oriented introduction of these elements into S. platensis biocomplexes retaining its protein composition and natural beneficial properties was shown. The absorption of mercury on growth dynamics of S. platensis and other bacterial strains was observed. Detoxification of Cr and Hg by Arthrobacter globiformis 151B was demonstrated. Microbial synthesis of technologically important silver nanoparticles by the novel actinomycete strain Streptomyces glaucus 71 MD and blue-green alga S. platensis were characterized by a combined use of transmission electron microscopy, scanning electron microscopy and energy-dispersive analysis of X-rays. It was established that the tested actinomycete S. glaucus 71 MD produces silver nanoparticles extracellularly when acted upon by the silver nitrate solution, which offers a great advantage over an intracellular process of synthesis from the point of view of applications. The synthesis of silver nanoparticles by S. platensis proceeded differently under the short-term and long-term silver action. (author)

  15. Microdosimetry for the characterization of the THOR epithermal neutron beam

    International Nuclear Information System (INIS)

    The epithermal neutron beam of the Tsing Hua Open-pool Reactor (THOR) was constructed for the study of boron neutron capture therapy (BNCT). The THOR epithermal neutron beam was mainly composed of thermal neutrons, fast neutrons, and photons. For fast neutrons and photons, the absorbed dose and the relative biological effectiveness (RBE) were used to characterize radiation dose and radiation quality. The short-ranged alpha particles and lithium ions produced from 10B(n,α)7Li reactions in the BNCT required cellular- and micro-dosimetry characterizations. Due to the non-uniform microdistribution of boron in cells, these characterizations should depend on the source-target geometry. In this case, the geometry-dependent specific cellular dose and lineal energy could be used to describe radiation dose and radiation quality. In the present work, cellular- and micro-dosimetry were studied for the THOR epithermal neutron beam. The specific cellular dose and lineal energy were calculated for thermal neutron-induced α-particles and 7Li-ions with different source-target geometry and various cell sizes. Applying the linear energy dependent-biological weighting function, the geometry-dependent RBE of thermal neutron-induced heavy particles was determined. Finally, the effective RBE of the THOR epithermal neutron beam was estimated for tumors and normal tissues of specified 10B concentrations. This effective RBE should be multiplied by the total absorbed dose to determine the corresponding biological dose required in the treatment planning.

  16. Method and apparatus for epithermal neutron porosity well logging

    International Nuclear Information System (INIS)

    The porosities of subsurface earth formations surrounding a borehole are investigated using a logging tool run in the wellbore by repeatedly irradiating the formations with discrete bursts of high energy neutrons, measuring the populations of epithermal neutrons at near and far locations from the neutron source, and also measuring the rate of decay of the epithermal neutron population at a third location following each neutron burst and deriving therefrom a measurement of the epithermal neutron slowing down time. Formation porosity values derived from the near-and-far location population measurements are corrected for detector standoff effects by use, in accordance with a predetermined empirical relationship, of the epithermal slow down time measurement. Alternatively, formation porosities may be derived both from the near-and-far location measurements and from the epithermal slowing down time measurement, and the two differently-derived porosity values may be used independently to provide enhanced information of formation porosity or they may be compared to derive a standoff-corrected porosity value. 6 figs

  17. Epithermal neutron formation for boron neutron capture therapy by adiabatic resonance crossing concept

    International Nuclear Information System (INIS)

    Low-energy protons from the cyclotron in the range of 15–30 MeV and low current have been simulated on beryllium (Be) target with a lead moderator around the target. This research was accomplished to design an epithermal neutron beam for Boron Neutron Capture Therapy (BNCT) using the moderated neutron on the average produced from 9Be target via (p, xn) reaction in Adiabatic Resonance Crossing (ARC) concept. Generation of neutron to proton ratio, energy distribution, flux and dose components in head phantom have been simulated by MCNP5 code. The reflector and collimator were designed in prevention and collimation of derivation neutrons from proton bombarding. The scalp-skull-brain phantom consisting of bone and brain equivalent material has been simulated in order to evaluate the dosimetric effect on the brain. Results of this analysis demonstrated while the proton energy decreased, the dose factor altered according to filters thickness. The maximum epithermal flux revealed using fluental, Fe and bismuth (Bi) filters with thicknesses of 9.4, 3 and 2 cm, respectively and also the epithermal to thermal neutron flux ratio was 103.85. The potential of the ARC method to replace or complement the current reactor-based supply sources of BNCT purposes. (author)

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

    International Nuclear Information System (INIS)

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

  19. Measurement of epithermal neutrons by a coherent demodulation technique

    CERN Document Server

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

    2000-01-01

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

  20. Correlated Observations of Epithermal Neutrons and Polar Illumination for Orbital Neutron Detectors

    Science.gov (United States)

    McClanahan, T. P.; Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Droege, G.; Evans, L. G.; Garvin, J.; Harshman, K.; Malakhov, A.; Livengood, T.; Milikh, G. M.; Namkung, M.; Nandikotkur, G.; Neumann, G.; Smith, D.; Sagdeev, R.; Sanin, A. G.; Starr, R. D.; Trombka, J. I.

    2012-01-01

    We correlate Lunar Reconnaisance Orbiter's (LRO) Lunar Exploration Neutron Detector (LEND) and the Lunar Prospector Neutron Spectrometer's (LPNS) orbital epithermal neutron maps of the Lunar high-latitudes with co-registered illumination maps derived from the Lunar Orbiter Laser Altimeter (LOLA) topography. Epithermal neutron count rate maps were derived from the LEND: 1) Collimated Sensor for Epithermal Neutrons, CSETNI-4 2) Uncollimated Sensor for Epithermal Neutrons, SETN and the Uncollimated Lunar Prospector: 3) Low-altitude and 4) High-altitude mapping phases. In this abstract we illustrate 1) and 3) and include 2) and 4) in our presentation. The correlative study provides unique perspectives on the regional epithermal neutron fluences from the Lunar polar regions under different detector and altitude configurations.

  1. The resonant detector and its application to epithermal neutron spectroscopy

    Science.gov (United States)

    Gorini, G.; Perelli-Cippo, E.; Tardocchi, M.; Andreani, C.; D'Angelo, A.; Pietropaolo, A.; Senesi, R.; Imberti, S.; Bracco, A.; Previtali, E.; Pessina, G.; Rhodes, N. J.; Schooneveld, E. M.

    2004-08-01

    New perspectives for epithermal neutron spectroscopy are being opened by the development of the resonant detector (RD) and its use on inverse geometry time of flight spectrometers at spallation sources. The RD was first proposed in the 1980s and was recently brought to a performance level exceeding conventional neutron-sensitive Li-glass scintillator detectors. It features a photon counter coupled to a neutron analyzer foil. Resonant neutron absorption in the foil results in the emission of prompt gamma rays that are detected in the photon counter. The dimensions of the RD set the spatial resolution that can be achieved, ranging from a fraction of a cm to several cm. It can thus be tailored to the construction of detector arrays of different geometry. The main results of the research on this kind of detector are reported leading to the present optimized RD design based on a combination of YAP scintillation photon counter and uranium or gold analyzer foils. This detector has already been selected for application in the upgrade of the VESUVIO spectrometer on ISIS. A special application is the Very Low Angle Detector (VLAD) bank, which will extend the kinematical region for neutron scattering to low momentum transfer (1 eV, thus allowing new experimental studies in condensed matter systems. The first results of tests made with prototype VLAD detectors are presented, confirming the usefulness of the RD for measurements at scattering angles as low as 2-5°.

  2. Thermal and epithermal neutron flux determination by K0 method

    International Nuclear Information System (INIS)

    In this paper we presented the methodology for thermal and epithermal neutron flux measurement by k0 method. The results obtained shown the feasibility of using this measures in high power in the RP-10 reactor in-core facilities. (authors)

  3. Epithermal neutron beam for BNCT research at Washington State University

    International Nuclear Information System (INIS)

    A new filter has been designed and analysed for the Washington State University TRIGATM research reactor. Optimum balance of epithermal flux and background KERMA was obtained with a FluentalTM and alumina filter. The epithermal neutron flux calculated by the DORT transport code was approximately 9 x 108 n/cm2-s with a background KERMA of about 3x10-13 Gy/n/cm2. Operation of the beam for animal testing is expected to commence in 2000. (author)

  4. Optimization study of epithermal neutron detector in prompt fission neutron uranium logging

    International Nuclear Information System (INIS)

    Background: Prompt fission neutron uranium logging is a method for uranium exploration. Pulsed neutron source and epithermal neutron detector are used to detect the prompt epithermal neutron from the fission of thermal neutron and 235U. Purpose: The efficiency of epithermal neutron detector of the logging instrument need to be improved. Methods: The energy distribution of fission neutron detected by the epithermal neutron detector, as well as the detection efficiency of epithermal neutron detector with different sizes of moderator are studied by Monte Carlo simulation. Results: Under the studied conditions, the optimal sizes of neutron moderating material and neutron detector are obtained, which is the combination of 0.5-mm thick cadmium, 1.1-cm thick polyethylene and 2.6-cm diameter 3He tube. Conclusions: In the space with outer diameter of 4.8 cm, the maximum of the epithermal neutron detection efficiency was achieved by combination of a 1.1-cm thick tube and a 2.6-cm diameter 3He moderator when using polyethylene or organic glass as the moderator material. (authors)

  5. Epithermal BNCT neutron beam design for a TRIGA II reactor

    International Nuclear Information System (INIS)

    In Finland a collaborative effort by Helsinki University Central Hospital, MAP Medical Technologies Inc. and VTT Reactor Laboratory has started aiming at BNCT of glioma patients. For this the capabilities of the FiR-1 TRIGA II 250 kW research reactor have been evaluated. The FiR-1 is located in the middle of the Otaniemi campus eight kilometers from the center of Helsinki and four kilometers from the Central Hospital. The power of the reactor was increased in 1965 to 250 kW and the instrumentation modernised in 1981. It is a pool reactor with graphite reflector and a core loading of 3 kg 20w% 235U in the special TRIGA uranium-zirconium hydride fuel (8-12 w% U, 91% Zr, 1% H). The advantages of using a TRIGA reactor for BNCT have already been pointed out earlier by Whittemore and have been verified in practice by the thermal neutron treatment work done at the Musashi 100 kW reactor. The advantages include a wide core face area and a wide spatial angle covered by the thermal-epithermal column system, large flux-per-Watt feature and inherent safety of the TRIGA fuel. Because of its wider applicability and less stringent requirements for clinical operation conditions, an epithermal neutron beam has been selected as the design goal. The epithermal flux should be sufficient for glioblastoma patient treatment: 109 epithermal neutrons/cm2/s with low enough fast neutron (-13Gy/epithermal n/cm2) and gamma contamination

  6. Epithermal Neutron Activation Analysis at the IBR-2 reactor of the Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research (Dubna)

    Science.gov (United States)

    Frontasyeva, M. V.

    2008-10-01

    Experience of the Neutron Activation Analysis (NAA) Department in employing epithermal activation in life sciences and materials science is summarized. The potential of a combination of epithermal activation and the suppression of Compton scattering and contributions from cascade-photon-emitting elements for raising NAA-based analytical studies up to a new level are discussed.

  7. Earth formation pulsed neutron porosity logging system utilizing epithermal neutron and inelastic scattering gamma ray detectors

    International Nuclear Information System (INIS)

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

  8. Exploratory calculations for boron capture therapy using epithermal neutron beams

    International Nuclear Information System (INIS)

    To get an insight into the problems of boron neutron capture therapy of brain tumours, some calculations of the neutron distribution in a spherical human skull have been made with an ANISN program. The energy of the source neutrons was varied from about 1 keV to about 100 keV. Two different neutron group structures were used with corresponding different cross section libraries. For a spherically symmetric irradiation of a skull with radius 10 cm a source neutron energy of about 50 - 100 keV gives a rather flat boron capture rate over a large part of the skull. This shows the advantage of using epithermal neutrons in the treatment of deepseated tumours by the boron neutron capture method. (Auth.)

  9. Optimization in Activation Analysis by Means of Epithermal Neutrons. Determination of Molybdenum in Steel

    International Nuclear Information System (INIS)

    Optimization in activation analysis by means of selective activation with epithermal neutrons is discussed. This method was applied to the determination of molybdenum in a steel alloy without recourse to radiochemical separations. The sensitivity for this determination is estimated to be 10 ppm. With the common form of activation by means of thermal neutrons, the sensitivity would be about one-tenth of this. The sensitivity estimations are based on evaluation of the photo peak ratios of Mo-99/Fe-59

  10. Epithermal neutron tomography using compact electron linear accelerator

    International Nuclear Information System (INIS)

    Neutron resonance absorption spectroscopy (N-RAS) with a pulsed neutron source can distinguish the dynamics of individual nuclides having resonance peaks on epithermal neutron region. The analyzed internal information of nuclide presence and its effective temperature can be reconstructed as distributions over the object cross-section using computed tomography (CT). Because some of the resonance absorption cross-sections have very large values, N-RAS could match the small neutron pulsed source by its high sensitivity. In this study, we have constructed a new instrument of N-RAS on a compact electron linac neutron source. Resonance absorption measurements and CT imaging with the instrument have succeeded for some kinds of nuclide.

  11. Characteristics of the new THOR epithermal neutron beam for BNCT

    International Nuclear Information System (INIS)

    A characterization of the new Tsing Hua open-pool reactor (THOR) epithermal neutron beam designed for boron neutron capture therapy (BNCT) has been performed. The facility is currently under construction and expected in completion in March 2004. The designed epithermal neutron flux for 1 MW power is 1.7x109 n cm-2 s-1 in air at the beam exit, accompanied by photon and fast neutron absorbed dose rates of 0.21 and 0.47 mGy s-1, respectively. With 10B concentrations in normal tissue and tumor of 11.4 and 40 ppm, the calculated advantage depth dose rate to the modified Snyder head phantom is 0.53 RBE-Gy min-1 at the advantage depth of 85 mm, giving an advantage ratio of 4.8. The dose patterns determined by the NCTPlan treatment planning system using the new THOR beam for a patient treated in the Harvard-MIT clinical trial were compared with results of the MITR-II M67 beam. The present study confirms the suitability of the new THOR beam for possible BNCT clinical trials

  12. A novel type epithermal neutron radiography detecting and imaging system

    CERN Document Server

    Balasko, M; Svab, E; Eoerdoegh, I

    1999-01-01

    The transfer technique is widely used for epithermal neutron radiography (ENR) for making images upon the object to be investigated. We propose to use instead of the photosensitive film a gamma sensitive scintillation screen (NaCe single crystal), that is monitored by a computer controlled low light level TV camera. The exposure time has been reduced to a duration of only a short fraction of that needed for the conventional transfer process. The presented ENR images consist of electronic signals that are handled by an advanced image processing and analyzing program, the Iman 1.4 version, using a task oriented video grabber.

  13. Development of the Epithermal Neutron Multiplicity Counter (ENMC)

    International Nuclear Information System (INIS)

    Introduction: Japan Atomic Energy Agency (JAEA) developed the Epithermal Neutron Multiplicity Counter (ENMC) under the joint study program with Los Alamos National Laboratory (LANL). ENMC is a new developed NDA system in order to improve the measurement uncertainty for impure MOX samples. The ENMC has a feature that it can measure not only thermal neutrons which is measured by the conventional NDA system (ex. PSMC: Plutonium Scrap Multiplicity Counter) but also epithermal neutrons. The thickness of high-density polyethylene (HDPE) of the ENMC was reduced to detect the epithermal neutrons. The number of 3He tubes and the pressure of 3He gas in tubes were increased in comparison with the PSMC because the cross section with 3He of epithermal neutron is smaller than one of thermal neutron. By these improvements, the ENMC has a high efficiency of neutron measurement of 64% and a short die-away time of 20 microseconds. The measurement of epithermal neutron before well moderating contributes to improve the measurement uncertainty considerably. Initial calibration test of the ENMC: The calibration test was performed at LANL and JAEA. As a result of the calibration test by using MOX samples, it was confirmed that the ENMC had high performance in comparison with the PSMC. For example, the measurement time of the ENMC to get the same measurement uncertainty was reduced about one-tenth to one-thirtieth in comparison with the PSMC. Functional test of the ENMC: JAEA attempted the functional test of the ENMC to utilize the ENMC capability to the full. This functional test had two phases. The purpose of the phase I functional test was to evaluate the measurement error of the ENMC. As a result of the phase I functional test, systematic error of the ENMC was 1.3%, the random error was 0.2-0.3%, and the total measurement uncertainty was 1.4% for large MOX samples with 100 minutes measurement. The dominant error factor was the systematic error and the major reasons for the error were

  14. Epithermal neutron beam adoption for lung and pancreatic cancer treatment by boron neutron capture therapy

    International Nuclear Information System (INIS)

    The depth-dose distributions were evaluated for possible treatment of both lung and pancreatic cancers using an epithermal neutron beam. The Monte Carlo Neutron Photon (MCNP) calculations showed that physical dose in tumors were 6 and 7 Gy/h, respectively, for lung and pancreas, attaining an epithermal neutron flux of 5 x 108 ncm-2s-1. The boron concentrations were assumed at 100 ppm and 30 ppm, respectively, for lung and pancreas tumors and normal tissues contains 1/10 tumor concentrations. The dose ratios of tumor to normal tissue were 2.5 and 2.4, respectively, for lung and pancreas. The dose evaluation suggests that BNCT using an epithermal neutron beam could be applied for both lung and pancreatic cancer treatment. (author)

  15. Renovation of epithermal neutron beam for BNCT at THOR

    International Nuclear Information System (INIS)

    Heading for possible use for clinical trial, THOR (Tsing Hua Open-pool Reactor) at Taiwan was shutdown for renovation of a new epithermal neutron beam in January 2003. In November 2003, concrete cutting was finished for closer distance from core and larger treatment room. This article presents the design base that the construction of the new beam is based on. The filter/moderator design along the beam is Cd(0.1 cm)+Al(10 cm)+FLUENTALTM(16 cm)+Al(10 cm)+FLUENTAL(24 cm)+Void(18 cm)+Cd(0.1 cm)+Bi(10 cm) with 6 cm Pb as reflector. Following the filter/moderator is an 88 cm long, 6 cm thick Bi-lined collimator with Li2CO3-PE at the end. The collimator is surrounded by Li2CO3-PE and Pb. The calculated beam parameters under 2 MW at the beam exit is phiepi=3.4x109 n/cm2/s, Df/phiepi=2.8x10-11 cGy cm2/n, Dγ/phiepi=1.3x10-11 cGy cm2/n, and J+/phi= 0.8. For a phantom placed 10 cm from beam exit, MCNP calculation shows that the advantage depth is 8.9 cm, and advantage ratio is 5.6 if boron concentration in tumor and normal tissue are assumed to be 65 and 18 ppm. The maximum dose rate for normal tissue is 50 cGy/min. The maximum therapeutic ratio is 6. The construction of the beam is scheduled to be finished by the end of April 2004

  16. Experiences of reconstruction of the epithermal neutron beam at THOR

    International Nuclear Information System (INIS)

    Tsing Hua Open-pool Reactor (THOR) had completed the renovation for an epithermal neutron beam in August 2004. The major tasks for this renovation were moderator/filter design and assembling, and concrete cutting for a better beam quality and larger irradiation room. Besides moderator/filter design, the associated works involved radiation monitoring, structure analysis, and shielding design. The radiation monitoring was performed to predict the probable accumulated dose for the workers involved in this reconstruction project. Special shielding design and construction processes were adopted to lower the radiation level and the probable accumulated dose for the workers. Before concrete cutting, structure analysis based on SAP-2000 code was performed to assure the structure is safe from the earthquake in Taiwan. A wall saw was then used for concrete cutting to enlarge the space of the irradiation room. Moderator/filter components were assembled on a trolley outside the beam exit prior to installation, which can effectively reduce the duration of a worker staying inside the reconstruction area and thereby reduce the accumulated dose. The shielding for the irradiation room was designed based on MCNP simulation using a pre-calculated source plane at the beam exit. The thickness of the concrete (density=3 g/cm3) of the walls and ceiling of the irradiation room were designed to be 100cm. On-going tasks include beam parameters measurement and in vitro/ in vivo study and calibration of treatment planning system, with the hope that the team can be ready for clinical trials in 2-3 years. (author)

  17. A prospect for the development of an epithermal neutron beam from the horizontal channel at the TRNC for brain tumors treatment based on the BNCT method

    International Nuclear Information System (INIS)

    In this work the epithermal neutron was development from horizontal channel VI at Tajoura research reactor which can be used for Boron Neutron Capture Therapy. The analysis of reactivity and control rod worth is performed by three dimensional continues energy MCNP-4C code with neutron cross section data from the ENDF/B-VI evaluation. The neutron beam which is developed for medical purpose is generated from the reactor core by means of U-235 fission. The neutrons leaking through the cavity of HC in Be-9 reflector is guided through a tube made of stainless steel to patient position. The HC has two wheels. The first wheel is small and is used as a gate. The second is large and have three positions one to close the gate, the second to open the gate while the third for loading collimator. The collimator consists of the moderators and filters to optimize the neutron beam which is installed in the loading position. The HC VI is extended to the room constructed to allow space for other horizontal channels users. materials are used to optimize the neutron beam which was selected depending on neutron beam properties related to core loading and control rod position. The results of the development study show that the required values for the neutron beam characteristic can be nearly reached. The different comparisons of the calculations performed using MCNP-4C code with the requirements values of characteristics neutron beam show that the result values of MCNP-4C code model are reliable. (author)

  18. The Local-time variations of Lunar Prospector epithermal-neutron data

    OpenAIRE

    Teodoro, L F A; Lawrence, D.J.; Eke, V. R.; Elphic, R. E.; Feldman, W. C.; Maurice, S.; Siegler, M. A.; Paige, D. A.

    2015-01-01

    We assess local-time variations of epithermal-neutron count rates measured by the Lunar Prospector Neutron Spectrometer. We investigate the nature of these variations and find no evidence to support the idea that such variations are caused by diurnal variations of hydrogen concentration across the lunar surface. Rather we find an anticorrelation between instrumental temperature and epithermal-neutron count rate. We have also found that the measured counts are dependent on the temperatures of ...

  19. The epithermal neutron beam for BNCT under construction at TAPIRO: Physics

    International Nuclear Information System (INIS)

    A column to provide an epithermal neutron beam suitable for experimental and clinical BNCT is nearing completion at the TAPIRO reactor (ENEA Casaccia, Rome). TAPIRO is a compact, low power (5 kW), helium-cooled, fast reactor. It has a hard neutron spectrum relative even to other fast reactors. In this paper some of the basic physics aspects of designing an epithermal neutron beam are considered, with reference to the TAPIRO beam

  20. Startup of the Fission Converter Epithermal Neutron Irradiation Facility at the MIT Reactor

    International Nuclear Information System (INIS)

    A new epithermal neutron irradiation facility, based on a fission converter assembly placed in the thermal column outside the reactor core, has been put into operation at the Massachusetts Institute of Technology Research Reactor (MITR). This facility was constructed to provide a high-intensity, forward-directed beam for use in neutron capture therapy with an epithermal flux of [approximately equal to]1010 n/cm2.s at the medical room entrance with negligible fast neutron and gamma-ray contamination. The fission converter assembly consists of 10 or 11 MITR fuel elements placed in an aluminum tank and cooled with D2O. Thermal-hydraulic criteria were established based on heat deposition calculations. Various startup tests were performed to verify expected neutronic and thermal-hydraulic behavior. Flow testing showed an almost flat flow distribution across the fuel elements with <5% bypass flow. The total reactivity change caused by operation of the facility was measured at 0.014 ± 0.002% δK/K. Thermal power produced by the facility was measured to be 83.1 ± 4.2 kW. All of these test results satisfied the thermal-hydraulic safety criteria. In addition, radiation shielding design measurements were made that verified design calculations for the neutronic performance

  1. Changes in epithermal neutron beam parameters with changing reactor core configuration

    International Nuclear Information System (INIS)

    The changes in epithermal neutron beam characteristics accompanying changes in the LVR-15 reactor core configuration were examined. The properties measured included the neutron spectrum, neutron fluence rate, and absorbed dose rate at the neutron beam outlet in air and in a thermalisation block. (orig.)

  2. Refinement of the dual ionisation chamber dosimetry carried out at the accelerator-based epithermal neutron beam facility of the University of Birmingham

    International Nuclear Information System (INIS)

    The paper presents the refined dual ionisation chamber technique used for in-air and in-phantom measurements in the Birmingham epithermal neutron beam. The study includes the derivation of the spectrum-dependent relative neutron sensitivity of the tissue-equivalent ionisation chamber. The average values over shallow depths for the kt parameter in A150 is 0.85 +/- 0.04, corresponding to an average value of 0.80 for water. For photon dosimetry in mixed fields, the formalism initially proposed by Munck af Rosenschold et al has been applied at a specific depth of 3 cm using MCNP4C as the radiation transport tool in the mixed beam and the reference calibration beam to generate electron fluence profiles in the detector gas cavities. The BEAMnrc code was used to generate the starting photon spectrum for the 8MV photon beam. The effect of the chosen energy-indexing algorithm on the in-cavity electron dose using the MNCP4C *F8 tally was also investigated. (author)

  3. Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

    Science.gov (United States)

    Gozani, Tsahi; King, Michael J.

    2016-01-01

    Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time ("E-T" correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple "one-group" models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E-T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.

  4. Dose measurements and calculations in the epithermal neutron beam at the Brookhaven Medical Research Reactor (BMRR)

    International Nuclear Information System (INIS)

    The characteristics of the epithermal neutron beam at BMRR were measured, calculated, and reported by R.G. Fairchild. This beam has already been used for animal irradiations. The authors anticipate that it will be used for clinical trials. Thermal and epithermal neutron flux densities distributions, and dose rate distributions, as a function of depth were measured in a lucite dog-head phantom. Monte Carlo calculations were performed and compared with the measured values

  5. Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions

    Science.gov (United States)

    Gozani, Tsahi; King, Michael J.

    2016-01-01

    Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time ("E-T" correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple "one-group" models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E-T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (fission modality a realizable SNM detection technique.

  6. Epithermal Neutron Activation Analysis of the Asian Herbal Plants

    Science.gov (United States)

    Baljinnyam, N.; Jugder, B.; Norov, N.; Frontasyeva, M. V.; Ostrovnaya, T. M.; Pavlov, S. S.

    2011-06-01

    Asian medicinal herbs Chrysanthemum (Spiraea aquilegifolia Pall.) and Red Sandalwood (Pterocarpus Santalinus) are widely used in folk and Ayurvedic medicine for healing and preventing some diseases. The modern medical science has proved that the Chrysanthemum (Spiraea aquilegifolia Pall.) possesses the following functions: reducing blood press, dispelling cancer cell, coronary artery's expanding and bacteriostating and Red Sandalwood (Pterocarpus Santalinus) is recommended against headache, toothache, skin diseases, vomiting and sometimes it is taken for treatment of diabetes. Species of Chrysanthemums were collected in the north-eastern and central Mongolia, and the Red Sandalwood powder was imported from India. Samples of Chrysanthemums (branches, flowers and leaves) (0.5 g) and red sandalwood powder (0.5 g) were subjected to the multi-element instrumental neutron activation analysis using epithermal neutrons (ENAA) at the IBR-2 reactor, Frank Laboratory of Neutron Physics (FLNP) JINR, Dubna. A total of 41 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Zr, Mo, Cd, Cs, Ba, La, Hf, Ta, W, Sb, Au, Hg, Ce, Nd, Sm, Eu, Tb, Dy, Yb, Th, U, Lu) were determined. For the first time such a large group of elements was determined in the herbal plants used in Mongolia. The quality control of the analytical results was provided by using certified reference material Bowen Cabbage. The results obtained are compared to the "Reference plant» data (B. Markert, 1992) and interpreted in terms of excess of such elements as Se, Cr, Ca, Fe, Ni, Mo, and rare earth elements.

  7. Epithermal Neutron Activation Analysis of the Asian Herbal Plants

    International Nuclear Information System (INIS)

    Asian medicinal herbs Chrysanthemum (Spiraea aquilegifolia Pall.) and Red Sandalwood (Pterocarpus Santalinus) are widely used in folk and Ayurvedic medicine for healing and preventing some diseases. The modern medical science has proved that the Chrysanthemum (Spiraea aquilegifolia Pall.) possesses the following functions: reducing blood press, dispelling cancer cell, coronary artery's expanding and bacteriostating and Red Sandalwood (Pterocarpus Santalinus) is recommended against headache, toothache, skin diseases, vomiting and sometimes it is taken for treatment of diabetes. Species of Chrysanthemums were collected in the north-eastern and central Mongolia, and the Red Sandalwood powder was imported from India. Samples of Chrysanthemums (branches, flowers and leaves)(0.5 g) and red sandalwood powder (0.5 g) were subjected to the multi-element instrumental neutron activation analysis using epithermal neutrons (ENAA) at the IBR-2 reactor, Frank Laboratory of Neutron Physics (FLNP) JINR, Dubna. A total of 41 elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, As, Se, Br, Rb, Sr, Zr, Mo, Cd, Cs, Ba, La, Hf, Ta, W, Sb, Au, Hg, Ce, Nd, Sm, Eu, Tb, Dy, Yb, Th, U, Lu) were determined. For the first time such a large group of elements was determined in the herbal plants used in Mongolia. The quality control of the analytical results was provided by using certified reference material Bowen Cabbage. The results obtained are compared to the ''Reference plant? data (B. Markert, 1992) and interpreted in terms of excess of such elements as Se, Cr, Ca, Fe, Ni, Mo, and rare earth elements.

  8. Quantitative analysis of silicates by instrumental epithermal neutron activation using (n,p) reactions

    International Nuclear Information System (INIS)

    Instrumental epithermal neutron activation (IENA) involves the use of a neutron filter to screen out the thermal portion of the reactor neutron energy spectrum. Both Cd and B are efficient neutron filters. The principal advantage of epithermal over conventional thermal neutron activation for elemental analysis of geological materials is that the most common rock forming elements, which activate strongly with thermal neutrons (Na, Al, P, K, Fe, and Sc), have their activities suppressed, relative to elements which have cross-sectional resonances in the epithermal energy region. One-gram samples of various silicate standard reference materials were encapsulated in polyethylene vials and irradiated in the Los Alamos Omega West Reactor epithermal facility. Only six elements (F, Si, Na, Fe, Ni, and Ti) were successfully determined in geological matrices via (n,p) reactions. The single standard deviations among the measurements were less than 10% in all cases. The production ratio of (n,p) to (n,γ) and (n,p) to (n,α) interfering reactions are included for silicate materials having Mason's average crustal abundance of elements. Epithermal activation via (n,p) reactions provides an alternative method for the determination of Fe, Al, Na, Ni, and F. The preferred techniques are probably thermal neutron activation for the first three elements, atomic absorption for Ni, and ion selective electrode for F.Titanium and Si can be measured much more sensitively using the (n,p) reaction than by thermal neutron activation. 4 tables

  9. Neutron scattering from -Ce at epithermal neutron energies

    Indian Academy of Sciences (India)

    A P Murani

    2008-10-01

    Neutron scattering data, using neutrons of incident energies as high as 2 eV, on -Ce and -Ce-like systems such as CeRh2, CeNi2, CeFe24, CeRu2, and many others that point clearly to the substantially localized 4f electronic state in these systems are reviewed. The present interpretation is contrary to the widely held view that the 4f electrons in these systems form a narrow itinerant electron 4f band.

  10. A state-of-the-art epithermal neutron irradiation facility for neutron capture therapy

    International Nuclear Information System (INIS)

    At the Massachusetts Institute of Technology (MIT) the first fission converter-based epithermal neutron beam (FCB) has proven suitable for use in clinical trials of boron neutron capture therapy (BNCT). The modern facility provides a high intensity beam together with low levels of contamination that is ideally suited for use with future, more selective boron delivery agents. Prescriptions for normal tissue tolerance doses consist of 2 or 3 fields lasting less than 10 min each with the currently available beam intensity, that are administered with an automated beam monitoring and control system to help ensure safety of the patient and staff alike. A quality assurance program ensures proper functioning of all instrumentation and safety interlocks as well as constancy of beam output relative to routine calibrations. Beam line shutters and the medical room walls provide sufficient shielding to enable access and use of the facility without affecting other experiments or normal operation of the multipurpose research reactor at MIT. Medical expertise and a large population in the greater Boston area are situated conveniently close to the university, which operates the research reactor 24 h a day for approximately 300 days per year. The operational characteristics of the facility closely match those established for conventional radiotherapy, which together with a near optimum beam performance ensure that the FCB is capable of determining whether the radiobiological promise of NCT can be realized in routine practice

  11. Characterisation of the epithermal neutron irradiation facility at the Portuguese research reactor using MCNP

    International Nuclear Information System (INIS)

    The radiation field at the epithermal beamline and irradiation chamber installed at the Portuguese Research Reactor (RPI) at the Campus Tecnológico e Nuclear of Instituto Superior Técnico was characterised in the context of Prompt Gamma Neutron Activation Analysis (PGNAA) applications. Radiographic films, activation foils and thermoluminescence dosimeters were used to measure the neutron fluence and photon dose rates in the irradiation chamber. A fixed-source MCNPX model of the beamline and chamber was developed and compared to measurements in the first step towards planning a new irradiation chamber. The high photon background from the reactor results in the saturation of the detector and the current facility configuration yields an intrinsic insensitivity to various elements of interest for PGNAA. These will be addressed in future developments. - Highlights: • An epithermal neutron irradiation facility modelled using MCNPX. • Foils and TLDs used to measure dose in chamber and compared to simulations. • Proposed modifications to the irradiation chamber outlined based upon results of simulations

  12. Correlation of Lunar South Polar Epithermal Neutron Maps: Lunar Exploration Neutron Detector and Lunar Prospector Neutron Detector

    Science.gov (United States)

    McClanahan, Timothy P.; Mitrofanov, I. G.; Boynton, W. V.; Sagdeev, R.; Trombka, J. I.; Starr, R. D.; Evans, L. G.; Litvak, M. L.; Chin, G.; Garvin, J.; Sanin, A. B.; Malakhov, A.; Milikh, G. M.; Harshman, K.; Finch, M. J.; Nandikotkur, G.

    2010-01-01

    The Lunar Reconnaissance Orbiter's (LRO), Lunar Exploration Neutron Detector (LEND) was developed to refine the lunar surface hydrogen (H) measurements generated by the Lunar Prospector Neutron Spectrometer. LPNS measurements indicated a approx.4,6% decrease in polar epithermal fluxes equivalent to (1.5+/-0,8)% H concentration and are direct geochemical evidence indicating water /high H at the poles. Given the similar operational and instrumental objectives of the LEND and LPNS systems, an important science analysis step for LEND is to test correlation with existing research including LPNS measurements. In this analysis, we compare corrected low altitude epithermal rate data from LPNS available via NASA's Planetary Data System (PDS) with calibrated LEND epithermal maps using a cross-correlation technique

  13. Optimization study for an epithermal neutron beam for boron neutron capture therapy at the University of Virginia Research Reactor

    International Nuclear Information System (INIS)

    The non-surgical brain cancer treatment modality, Boron Neutron Capture Therapy (BNCT), requires the use of an epithermal neutron beam. This purpose of this thesis was to design an epithermal neutron beam at the University of Virginia Research Reactor (UVAR) suitable for BNCT applications. A suitable epithermal neutron beam for BNCT must have minimal fast neutron and gamma radiation contamination, and yet retain an appreciable intensity. The low power of the UVAR core makes reaching a balance between beam quality and intensity a very challenging design endeavor. The MCNP monte carlo neutron transport code was used to develop an equivalent core radiation source, and to perform the subsequent neutron transport calculations necessary for beam model analysis and development. The code accuracy was validated by benchmarking output against experimental criticality measurements. An epithermal beam was designed for the UVAR, with performance characteristics comparable to beams at facilities with cores of higher power. The epithermal neutron intensity of this beam is 2.2 x 108 n/cm2 · s. The fast neutron and gamma radiation KERMA factors are 10 x 10-11cGy·cm2/nepi and 20 x 10-11 cGy·cm2/nepi, respectively, and the current-to-flux ratio is 0.85. This thesis has shown that the UVAR has the capability to provide BNCT treatments, however the performance characteristics of the final beam of this study were limited by the low core power

  14. The Local-time variations of Lunar Prospector epithermal-neutron data

    CERN Document Server

    Teodoro, L F A; Eke, V E; Elphic, R E; Feldman, W C; Maurice, S; Siegler, M A; Paige, D A

    2015-01-01

    We assess local-time variations of epithermal-neutron count rates measured by the Lunar Prospector Neutron Spectrometer. We investigate the nature of these variations and find no evidence to support the idea that such variations are caused by diurnal variations of hydrogen concentration across the lunar surface. Rather we find an anticorrelation between instrumental temperature and epithermal-neutron count rate. We have also found that the measured counts are dependent on the temperatures of the top decimeters of the lunar subsurface as constrained by the Lunar Reconnaissance Orbiter Diviner Lunar Radiometer Experiment temperature measurements. Finally, we have made the first measurement of the effective leakage depth for epithermal-neutrons of ~20 cm.

  15. The influence of an additional filter in epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    Additional filters of tungsten and sodium in different thicknesses have been used in the epithermal neutron activation analysis of geological samples to reduce the interferences caused by resonance neutron capture in these two elements. The results show that a selective reduction of the interfering activities in favor of the activities sought can be obtained. Improvements in terms of detection sensitivity and precision in the γ-spectrometric determinations of Sc, Fe, Co, La, Sm, Eu, Gd, Tb, Yb, Lu, Th and W have been calculated. The possible applications of the filtered epithermal neutron activation analysis (FENA) method to different kinds of samples are also briefly discussed. (author)

  16. Photon quality correction factors for ionization chambers in an epithermal neutron beam

    International Nuclear Information System (INIS)

    The radiation field of a neutron beam optimized for boron neutron capture therapy constitutes of a mixture of a photon and a neutron component. The photon and neutron absorbed dose to tissue have different biological effectiveness, suggesting that they should be determined separately. The thermal neutron absorbed dose component can be determined in phantom materials using activation probes. The photon and the fast neutron component can be determined using ionization chambers. The response of ionization chambers in different photon beams has recently been reported for conventional radiation therapy. Thus far, the beam quality correction factors kQ-factors) for photons for ionization chambers in epithermal neutron beams have been assumed equal to unity or estimated through measurements in accelerator produced photon beams. In the present study the kQγ- factors have been determined for two commercially available detectors in an epithermal neutron beam optimized for BNCT using the Monte Carlo method

  17. Epithermal neutron beam adoption for liver cancer treatment by boron and gadolinium neutron capture therapy

    International Nuclear Information System (INIS)

    Comparative evaluation was made on depth-dose distribution in boron neutron capture therapy (B-NCT) and gadolinium one (Gd-NCT) for the treatments of liver cancers. At present, epithermal neutron beam is expected to be applicable to the treatment of deep and widespread tumors. ICRU computational model of ADAM and EVA was used as a liver phantom loading a tumor at depth of 6 cm in its central region. Epithermal neutron beam of Musashi reactor was used as the primary neutron beam for the depth-dose calculation. Calculation was conducted using the three-dimensional continuous-energy Monte Carlo code MCNP4A. The doses observed in both NCTs were bumped over the tumor region but the dose for Gd-NCT was not so tumor-specific compared with that for BNCT because radiation in Gd-NCT was due to γ-ray. The mean physical dose was 4 Gy/h for boron 30 ppm and 5 Gy/h for Gd 1000 ppm when exposed to an epithermal neutron flux of 5x108 n/cm-2/sec and the dose ratio of tumor-to normal tissue was 2.7 for boron and 2.5 for Gd. The lethal dose of 50 Gy for the liver can be accomplished under conditions where the dose has not reached 25 Gy, the tolerance dose of the normal tissue. This seems very encouraging and indicating that both B-NCT and Gd-NCT are applicable for the treatment for liver cancer. However, if normal tissue contain 1/4 of the tumor concentration of boron or Gd, the BNCT would still possible when considering a large RBE value for 10B(n, α) reaction but the Gd-NCT would impossible for deep liver treatment. (M.N.)

  18. Elemental analysis of airborne particulate by using thermal and epithermal neutron activation

    International Nuclear Information System (INIS)

    Thermal neutron activation analysis was used to determine Al, Br, Ca, Cl, Mn, Na, V, and Ti concentrations, whereas epithermal neutron activation analysis was used to determine Cu, I and Si concentrations. Counting by Compton suppression both in thermal neutron activation and epithermal neutron activation analysis showed the significantly different on detection limit of element compare with normal counting system. It revealed counting by Compton suppression gave better result. The enrichment factor of elements indicated that V and Mn were enriched in several fine particulate samples. Ca, Si and Na were not enriched, whereas Br, I and Cl were enriched in fine airborne particulate or in coarse one. It was found that Cl and Na did not have correlation, while Br and I showed the same enrichment the same enrichment trend and high correlation (0,9). It means that Br and I were from the same pollutant source. It could concluded that the thermal neutron and epithermal neutron activations analysis combined with counting by Compton suppression could enhance sensitivity of analysis of elemental air bone particulate that was very useful in air pollution study. Key words : activation analysis, thermal neutron, epithermal neutron, Compton

  19. The Vertical Distribution of Buried Volatiles at the Moon revealed by Thermal and Epithermal Neutron Fluxes from LEND Observations

    Science.gov (United States)

    Chin, G.; Sagdeev, R.; Su, J. J.; Murray, J.; Livengood, T. A.

    2015-12-01

    Determining the quantity and vertical distribution of volatile species on and below the surface of planetary bodies is vital to understand the primordial chemical inventory and subsequent evolution of planets. Volatiles may provide resources to support future human exploration. This is particularly true for the Moon, which is well observed by many methods from ground-based, lunar orbit, and in situ, and is an accessible destination or way station for human exploration. We present Geant4 models of relative fluxes of Fast, Epithermal, and Thermal neutron emission generated in a planetary regolith by galactic cosmic rays to reveal the first 1-2 meters vertical structure of embedded hydrogen or water. Varying ratios of Thermal versus Epithermal, low-energy-Epithermal versus high-energy-Epithermal, and Thermal versus Fast neutron emissions are diagnostics of the depth in which hydrogen/water layers are buried within the top 1-2 meters of the regolith. In addition, we apply model calculations to Lunar Exploration Neutron Detector (LEND) thermal and epithermal data, acquired on the Lunar Reconnaissance Orbiter (LRO), in specific regions of the Moon to retrieve the vertical distribution of buried ice from the remote sensing information. GEANT4 is a set of particle physics transport simulation codes that exploits object-oriented software methods to deliver a comprehensive and flexible toolkit that is modular and extensible, based on a free open-source development model. GEANT4 has become a standard tool to simulate applications as diverse as particle telescope and detector response, space radiation shielding and optimization, total ionizing dose in spacecraft components, and biological effects of radiation.

  20. On-line neutron monitoring system of epithermal neutron beam for BNCT at THOR

    International Nuclear Information System (INIS)

    This paper aims to introduce the on-line neutron monitoring system (NMS) of epithermal neutron beam for BNCT at THOR and following tests. The NMS consists of three miniature fission chambers (Centronic, FC4A) and one gamma-ray monitor. The data acquisition and display are controlled by an in-house graphical user interface program. Both the real-time counting rates and the accumulated counts will be displayed simultaneously during irradiation. When the accumulated count reaches a preset value, the NMS will send a signal to the reactor operator to shut down the reactor. Examinations have been performed to demonstrate the system's reliability and linearity for desired reactor power range. The neutron counting rates were calibrated to the reaction rate of the gold foil measured free-in-air at the beam outlet center. By using the on-line NMS, an unstable fluctuation and long-term depression of epithermal neutron beam intensity was observed. It is suggested to normalize each performed irradiation by the average reading of the NMS. (author)

  1. The spatial distribution of thermal and epithermal neutrons in a graphite moderated spallation neutron field

    International Nuclear Information System (INIS)

    The Gamma-3 assembly is located at the Joint Institute for Nuclear Research, Dubna, Russia. It consists of a cylindrical lead target (ø = 8 cm, L = 58.8 cm) surrounded by reactor grade graphite (110 × 110 × 60 cm). The target was irradiated with a beam of 1.6 GeV deuterons from the Nuclotron accelerator and CR-39 track detectors coupled to LR-115 2B film were used to measure the slow neutron distribution on the surface of the graphite. The detection efficiency of the CR-39 in the CR-39/LR-115 2B system was measured using a custom made calibration setup and found to be (1.12 ± 0.05) × 10−3 and (6.1 ± 1.2) × 10−4 tracks per neutron, for thermal and epithermal neutrons respectively, under the etching and counting procedures described in this work. The irradiation of the Gamma-3 was also simulated using MCNPX 2.7 Monte Carlo code and good agreement between the experimental and calculated track densities was found. This serves as a good validation for the computational models used to simulate spallation neutron production, transport and moderation. - Highlights: • Distribution of graphite moderated spallation neutrons measured with CR39/LR115 2B. • The spallation neutrons were generated by interaction of 1.6 GeV d with Pb-target. • CR-39 detector was calibrated using a standard neutron field. • The thermal and epithermal neutron fluences were determined. • Experimental findings are in good agreement with MCNPX code predictions

  2. Spectral characterization of the epithermal-neutron beam at the Brookhaven medical research reactor

    International Nuclear Information System (INIS)

    The power burst facility boron neutron capture therapy (PBF/BNCT) program schedule required the use of an epithermal-neutron beam before the PBF would be available. The beam was needed to carry out the acute, dose-tolerance study on healthy canines and the treatment protocol on spontaneous tumor canines. Calculations on available U.S. test reactors confirmed that the Brookhaven medical research reactor (BMRR) would be capable of providing an epithermal-neutron beam with sufficient intensity while limiting the fast-neutron and gamma dose contamination to acceptable levels for the canine irradiation studies. A joint Idaho National Engineering Laboratory (INEL)/Brookhaven National Laboratory (BNL) program was instituted to design, construct, install, and measure the performance of an epithermal-neutron beam filter for the BMRR. Aluminum oxide was selected as the filter material because it provided the desired neutron spectrum characteristics given the physical constraints of the available BMRR irradiation beam port. Neutron spectrum measurements of the exit beam were undertaken by INEL as a means to evaluate the performance of the new filter and the validity of neutron transport calculations. The preliminary data from activation measurements were presented at the Neutron Beam Design Workshop at Massachusetts Institute of Technology (MIT) in March 1989. The updated activation results and the proton-recoil measurements are presented in this paper and are compared with predictions derived from a two-dimensional transport calculation

  3. Reactor AQUILON. The hardening of neutron spectrum in natural uranium rods, with a computation of epithermal fissions (1961)

    International Nuclear Information System (INIS)

    - Microscopic flux measurements in reactor Aquilon have allowed to investigate the thermal and epithermal flux distribution in natural uranium rods, then to obtain the neutron spectrum variations in uranium, Wescott 'β' term of the average spectrum in the rod, and the ratio of epithermal to therma fissions. A new definition for the infinite multiplication factor is proposed in annex, which takes into account epithermal parameters. (authors)

  4. Distribution of 35 Elements in Peat Cores from Ombrotrophic Bogs Studied by Epithermal Neutron Activation Analysis

    CERN Document Server

    Frontasyeva, M V

    2004-01-01

    In ombrotrophic bogs the surface peat layer is supplied with chemical substances only from the atmosphere. Peat cores from these bogs therefore can be used to study temporal trends in atmospheric deposition of pollutants. In this work epithermal neutron activation analysis was applied for the first time to study the distribution of 35 elements in peat profiles from ombrotrophic bogs. The selected examples were from Finnmark county in northern Norway: one pristine site far from any local pollution source, and another strongly affected by long-term operation of Russian copper-nickel smelters located close to the border. The elements are classified with respect to their behavior in the uppermost 40 cm of the peat, and similarities and differences between the two profiles are discussed. As compared with other more commonly used analytical techniques based on acid decomposition of the sample ENAA has the advantage of providing the total concentrations of the elements.

  5. Development of new instrumentation for epithermal neutron scattering at very low angles

    International Nuclear Information System (INIS)

    New perspectives for epithermal neutron spectroscopy are opened up by the recent developments of Resonance Detectors (RD) for inverse geometry time-of-flight spectrometers at pulsed neutron sources. The RD is based on the combination of an analyser foil used as neutron-to-gamma converter and a suitable photon detector. Here, we report on the state of the RD which is based on a YAP scintillator viewing a natural uranium analyser foil. The response of the YAP detector to the radiative capture γ emission from the uranium analyser foil has been characterized with a bi-parametric measurement of a reference Pb sample, which allowed simultaneous measurements of both neutron time-of-flight and γ pulse height (energy) spectra. The analysis of the γ pulse height and neutron time-of-flight spectra permitted to identify the signal and background components. These measurements showed that a significant improvement in the signal-to-background ratio can be achieved by setting a lower level discrimination on the photon energy at about 600keV. The first application of RD is the Very Low Angle Detector Bank (VLAD) which is planned to be installed in the next three years as an upgrade of the VESUVIO spectrometer, at the ISIS pulsed neutron source. VLAD will extend the (q,ω) kinematical to low wave vector transfers (q10A-1) coupled to high-energy transfers (-bar ω>1eV), which is still unexplored by neutron scattering experiments. The first measurements obtained on an ice sample with a VLAD prototype consisting of four RD units are presented here

  6. Optimization study for an epithermal neutron beam for boron neutron capture therapy at the University of Virginia Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Burns, T.D. Jr.

    1995-05-01

    The non-surgical brain cancer treatment modality, Boron Neutron Capture Therapy (BNCT), requires the use of an epithermal neutron beam. This purpose of this thesis was to design an epithermal neutron beam at the University of Virginia Research Reactor (UVAR) suitable for BNCT applications. A suitable epithermal neutron beam for BNCT must have minimal fast neutron and gamma radiation contamination, and yet retain an appreciable intensity. The low power of the UVAR core makes reaching a balance between beam quality and intensity a very challenging design endeavor. The MCNP monte carlo neutron transport code was used to develop an equivalent core radiation source, and to perform the subsequent neutron transport calculations necessary for beam model analysis and development. The code accuracy was validated by benchmarking output against experimental criticality measurements. An epithermal beam was designed for the UVAR, with performance characteristics comparable to beams at facilities with cores of higher power. The epithermal neutron intensity of this beam is 2.2 {times} 10{sup 8} n/cm{sup 2} {center_dot} s. The fast neutron and gamma radiation KERMA factors are 10 {times} 10{sup {minus}11}cGy{center_dot}cm{sup 2}/n{sub epi} and 20 {times} 10{sup {minus}11} cGy{center_dot}cm{sup 2}/n{sub epi}, respectively, and the current-to-flux ratio is 0.85. This thesis has shown that the UVAR has the capability to provide BNCT treatments, however the performance characteristics of the final beam of this study were limited by the low core power.

  7. Imaging of gamma and neutron dose distributions at LVR-15 epithermal beam by means of FGLDs

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G., E-mail: grazia.gambarini@mi.infn.it [Department of Physics, Universita degli Studi, Milan (Italy)] [INFN, Istituto Nazionale di Fisica Nucleare, Section of Milan, Milan (Italy); Bartesaghi, G. [Department of Physics, Universita degli Studi, Milan (Italy)] [INFN, Istituto Nazionale di Fisica Nucleare, Section of Milan, Milan (Italy); Carrara, M. [The Fondazione IRCCS ' Istituto Nazionale Tumori' , Milan (Italy); Negri, A. [INFN, Istituto Nazionale di Fisica Nucleare, Section of Milan, Milan (Italy); Paganini, L. [Department of Physics, Universita degli Studi, Milan (Italy); Vanossi, E. [INFN, Istituto Nazionale di Fisica Nucleare, Section of Milan, Milan (Italy); Burian, J.; Marek, M.; Viererbl, L.; Klupak, V.; Rejchrt, J. [Department of Reactor Physics, NRI Rez, plc (Czech Republic)

    2011-12-15

    Gamma and fast neutron dose spatial distributions have been measured at the collimator exit of the epithermal neutron beam of LVR-15 reactor (Rez). Measurements were performed by means of optically analyzed Fricke-gel-layer detectors. The separation of the two dose contributions has been achieved by suitable pixel-to-pixel elaboration of the light transmittance images of Fricke-gel-layer detectors prepared with water and heavy water.

  8. Design of a high-flux epithermal neutron beam using 235U fission plates at the Brookhaven Medical Research Reactor.

    Science.gov (United States)

    Liu, H B; Brugger, R M; Rorer, D C; Tichler, P R; Hu, J P

    1994-10-01

    Beams of epithermal neutrons are being used in the development of boron neutron capture therapy for cancer. This report describes a design study in which 235U fission plates and moderators are used to produce an epithermal neutron beam with higher intensity and better quality than the beam currently in use at the Brookhaven Medical Research Reactor (BMRR). Monte Carlo calculations are used to predict the neutron and gamma fluxes and absorbed doses produced by the proposed design. Neutron flux measurements at the present epithermal treatment facility (ETF) were made to verify and compare with the computed results where feasible. The calculations indicate that an epithermal neutron beam produced by a fission-plate converter could have an epithermal neutron intensity of 1.2 x 10(10) n/cm2.s and a fast neutron dose per epithermal neutron of 2.8 x 10(-11) cGy.cm2/nepi plus being forward directed. This beam would be built into the beam shutter of the ETF at the BMRR. The feasibility of remodeling the facility is discussed. PMID:7869995

  9. Theoretical and experimental study of collectrons for epithermal neutron flux in reactors

    International Nuclear Information System (INIS)

    A theoretical study of nuclear reactions and electric charge displacements arising in sensitivity to thermal and epithermal neutrons in collectrons allowed a computer code conception. Collectrons in Rhodium, Silver, Cobalt, Hafnium, Erbium, Gadolinium and Holmium have been tested in different radiation fields given by neutron or gamma filters irradiated in different places of Melusine and Siloe reactors. Some emitters were covered with different steel, nickel or zircaloy thicknesses. Theoretical and experimental results are consistent; that validate the computer code and show possibilities and necessity of covering collectron emitters to reduce or cancel the gamma sensitivity and to improve response instantaneity. A selective measurement of epithermal neutron flux can by this way, made by associating two types of collectrons

  10. The dose comparison between the THOR and HFR epithermal neutron beams

    International Nuclear Information System (INIS)

    This study is a part of the beam comparison campaign, inter-center dose comparison, between boron neutron capture therapy facilities at the Tsing Hua Open-pool Reactor and the High Flux Reactor. The clinical information exchange can improve the dosimetry uncertainty for medical physics in a mixed field. The method of paired Mg(Ar) and TE(TE) ionization chambers was used to determine the gamma-ray and neutron dose rates. Furthermore, activation foils, including gold, copper, and manganese, were employed to estimate the thermal and epithermal neutron fluxes. Measurements were performed free in air and also in a PMMA phantom. All the chambers were calibrated using a 60Co primary standard source at the Institute of Nuclear Energy Research, Taiwan. Spectrum dependent neutron sensitivity of TE(TE) chamber is one of the important parameters to evaluate dose components. The requested neutron spectra were calculated by the Monte Carlo code MCNP. The measured thermal neutron fluxes, gamma-ray and neutron dose rates of the THOR beam in the phantom were 2.6, 2.2, and 2.1 times of the HFR beam at 2.5-cm depth, respectively. The higher thermal neutron flux and neutron and gamma-ray dose rates are due to the higher epithermal neutron beam intensity of the THOR.

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

    Science.gov (United States)

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

    2007-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-15

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

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

    International Nuclear Information System (INIS)

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

  14. Power burst reactor facility as an epithermal neutron source for brain cancer therapy

    International Nuclear Information System (INIS)

    The Power Burst Facility (PBF) reactor is considered for modification to provide an intense, clean source of intermediate-energy (epithermal) neutrons desirable for clinical studies of neutron capture therapy (NCT) for malignant tumors. The modifications include partial replacement of the reflector, installation of a neutron-moderating, shifting region, addition shielding, and penetration of the present concrete shield with a collimating and (optionally) filtering region. The studies have indicated that the reactor, after these modifications, will be safely operable at full power (28 MW) within the acceptable limits of the plant protection systems. The neutron beam existing from the collimator port is predicted to be of sufficient intensity (∼ 1010) neutrons/cm2-s) to provide therapeutic doses in very short irradiation times. The beam would be relatively free of undesirable fast neutrons, thermal neutrons and gamma rays. The calculated neutron energy spectrum and associated gamma rays in the beam were provided as input in simulation studies that used a computer model of a patient with a brain tumor to determine predicted dose rates to the tumor and healthy tissue. The results of this conceptual study indicate an intense, clean beam of epithermal neutrons for NCT clinical trials is attainable in the PBF facility with properly engineered design modifications. 9 references, 11 figures, 3 tables

  15. Filtered epithermal quasi-monoenergetic neutron beams at research reactor facilities

    International Nuclear Information System (INIS)

    Filtered neutron techniques were applied to produce quasi-monoenergetic neutron beams in the energy range of 1.5–133 keV at research reactors. A simulation study was performed to characterize the filter components and transmitted beam lines. The filtered beams were characterized in terms of the optimal thickness of the main and additive components. The filtered neutron beams had high purity and intensity, with low contamination from the accompanying thermal emission, fast neutrons and γ-rays. A computer code named “QMNB” was developed in the “MATLAB” programming language to perform the required calculations. - Highlights: • Quasi-monoenergetic neutron beams in energy range from (1.5–133) keV. • Interference between the resonance and potential scattering amplitudes. • Epithermal neutron beams used in BNCT

  16. Epithermal Neutron Activation Analysis of Spirulina platensis Biomass, of the C-Phycocianin and of DNA Extracted from It

    CERN Document Server

    Mosulishvili, L M; Belokobylsky, A I; Kirkesali, E I; Khizanishvili, A I; Pomyakushina, E V

    2002-01-01

    The epithermal neutron activation analysis (ENAA) was used for study of the biomass of Spirulina platensis. The background levels of concentration 27 macro-, micro- and trace elements ranging from 10^{-3} up to 10^{4} ppm were determined. It was found that the biomass of spirulina does not contain toxic elements above the tolerance levels and can be utilized as a matrix of pharmaceuticals based on it. The concentrations of basic elements in C-phycocianin and DNA extracted from Spirulina platensis were determined by ENAA. A comparison of the element content of a whole spirulina biomass with that of a refined C-phycocianin preparation was made.

  17. Epithermal neutron activation analysis of Spirulina platensis biomass, of the C-phycocianin and of DNA extracted from it

    International Nuclear Information System (INIS)

    The epithermal neutron activation analysis (ENAA) was used for study of the biomass of Spirulina platensis. The background levels of concentration of 27 macro-, micro- and trace elements ranging from 10-3 up to 104 ppm were determined. It was found that the biomass of Spirulina does not contain toxic elements above the tolerance levels and can be utilized as a matrix of pharmaceuticals based on it. The concentrations of basic elements in C-phycocianin and DNA extracted from Spirulina platensis were determined by ENAA. A comparison of the element content of a whole Spirulina biomass with that of a refined C-phycocianin preparation was made

  18. Can epithermal boron neutron capture therapy treat primary and metastatic liver cancer?

    International Nuclear Information System (INIS)

    Full text: The poor prognosis of metastatic cancer to the liver calls for the investigation of alternative treatment modalities. This paper analyses the possible use of epithermal boron neutron capture therapy for the palliative treatment of these cancers. We examine possible treatment planning scenarios for selected tumour to liver boron ratios, and specifically for the epithermal beam at the HFR, Petten. It is required that a therapeutic ratio> 1 be achieved over the entire organ. Monte Carlo calculations were performed using the radiation transport code MCNP. The geometrical model used a 'variable voxel' technique to reconstruct an anthropomorphic phantom from CT scans. Regions of interest such as the liver were modelled to a resolution of a few millimetres, whereas surrounding regions were modelled with lesser detail thereby facilitating faster computation time. Three dimensional dose distributions were calculated for a frontal beam directed at the liver, and found to be in satisfactory agreement with measurements using bare and cadmium covered gold foils, PIN and MOSFET dosimeters for fast neutron and gamma measurements respectively. Dose distributions were calculated for orthogonal epithermal neutron beams to the front and side, using the parameters of the epithermal beam at Petten, and assumed tumour and normal tissue boron-10 concentrations of 30 ppm and 7.5 ppm boron-10 respectively. The therapeutic ratio (i e the dose to the tumour relative to the maximum dose to normal tissue) was found to be about 1.8, reducing to unity for the limiting condition of a tumour in the posterior liver. This result opens up the possibility of palliative therapy for the management of primary and metastatic liver cancer

  19. Epithermal Neutron Observations and Lunar South Pole Targeting for LCROSS Impact Planning using the Lunar Reconnaissance Orbiter (LRO), Lunar Exploring Neutron Detector (LEND)

    Science.gov (United States)

    McClanahan, T. P.; Mitrofanov, I.; Boynton, W. V.; Chin, G.; Colaprete, A.; Evans, L. G.; Garvin, J.; Harshman, K.; Litvak, R.; Malakhov, A.; Milikh, G. M.; Nandikotkur, G.; Sagdeev, R.; Sanin, A. B.; Smith, D. E.; Starr, R. D.; Trombka, J.

    2009-01-01

    LCROSS impact targeting and planning efforts included quantifying South Polar epithermal neutron flux depressions in early LEND mapped results to maximize the expected plume Hydrogen (H) yield. Epithermal neutron surface fluxes are a key geochemical indicator of surface Hydrogen (H) concentration inferred to be elevated in polar permanent shadow regions (PSR). LCROSS impact target regions were delineated as (PSR) using illumination modeling of polar topography. To quantify targets potential yield for LCROSS, LEND epithermal neutron flux observations were integrated over LCROSS targets of interest and compared to background observations. Discussion will define methods review impact prior estimates and contrast post impact results.

  20. Ultraslow Wave Nuclear Burning of Uranium-Plutonium Fissile Medium on Epithermal Neutrons

    CERN Document Server

    Rusov, V D; Eingorn, M V; Chernezhenko, S A; Kakaev, A A

    2014-01-01

    For a fissile medium, originally consisting of uranium-238, the investigation of fulfillment of the wave burning criterion in a wide range of neutron energies is conducted for the first time, and a possibility of wave nuclear burning not only in the region of fast neutrons, but also for cold, epithermal and resonance ones is discovered for the first time. For the first time the results of the investigation of the Feoktistov criterion fulfillment for a fissile medium, originally consisting of uranium-238 dioxide with enrichments 4.38%, 2.00%, 1.00%, 0.71% and 0.50% with respect to uranium-235, in the region of neutron energies 0.015-10.0eV are presented. These results indicate a possibility of ultraslow wave neutron-nuclear burning mode realization in the uranium-plutonium media, originally (before the wave initiation by external neutron source) having enrichments with respect to uranium-235, corresponding to the subcritical state, in the regions of cold, thermal, epithermal and resonance neutrons. In order to...

  1. The design, construction and performance of a variable collimator for epithermal neutron capture therapy beams

    International Nuclear Information System (INIS)

    A patient collimator for the fission converter based epithermal neutron beam (FCB) at the Massachusetts Institute of Technology Research Reactor (MITR-II) was built for clinical trials of boron neutron capture therapy (BNCT). A design was optimized by Monte Carlo simulations of the entire beam line and incorporates a modular construction for easy modifications in the future. The device was formed in-house by casting a mixture of lead spheres (7.6 mm diameter) in epoxy resin loaded with either 140 mg cm-3 of boron carbide or 210 mg cm-3 of lithium fluoride (95% enriched in 6Li). The cone shaped collimator allows easy field placement anywhere on the patient and is equipped with a laser indicator of central axis, beam's eye view optics and circular apertures of 80, 100, 120 and 160 mm diameter. Beam profiles and the collateral dose in a half-body phantom were measured for the 160 mm field using fission counters, activation foils as well as tissue equivalent (A-150) and graphite walled ionization chambers. Leakage radiation through the collimator contributes less than 10% to the total collateral dose up to 0.15 m beyond the edge of the aperture and becomes relatively more prominent with lateral displacement. The measured whole body dose equivalent of 24 ± 2 mSv per Gy of therapeutic dose is comparable to doses received during conventional therapy and is due principally (60-80%) to thermal neutron capture reactions with boron. These findings, together with the dose distributions for the primary beam, demonstrate the suitability of this patient collimator for BNCT

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

    International Nuclear Information System (INIS)

    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 ?)waterair, 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 60Co gamma beams. In photon beam dosimetry (S I ?)waterair 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). To improve the accuracy of

  3. 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

  4. Physical parameters and biological effects of the LVR-15 epithermal neutron beam

    International Nuclear Information System (INIS)

    Monitoring of the physical and biological properties of the epithermal neutron beam constructed at the multipurpose LVR-15 nuclear reactor for NCT therapy of brain tumors showed that its physical and biological properties are stable in time and independent on an ad hoc reconfiguration of the reactor core before its therapeutic use. Physical parameters were monitored by measurement of the neutron spectrum, neutron profile, fast neutron kerma rate in tissue and photon absorbed dose, the gel dosimetry was used with the group of standard measurement methods. The RBE of the beam, as evaluated by 3 different biological models, including mouse intestine crypt regeneration assay, germinative zones of the immature rat brain and C6 glioma cells in culture, ranged from 1.70 to 1.99. (author)

  5. Thermal and epithermal neutron dosimetry by induced activation in cold-pressed pellets of TL phosphor-mixture

    International Nuclear Information System (INIS)

    Measurement of thermal and epithermal neutron exposures have been attempted using CaF2 and CaSO4 TL phosphors cold-pressed into pellets after mixing with carefully chosen fluxing agents which have appreciable cross sections in this neutron energy range. Epithermal and thermal exposures have been arbitrarily distinguished by the difference obtained with and without cadmium filters covering the pellets. Some of the mixture investigated are: (CaF2 + KBr) and (CaSO4 + KBr) for thermal neutron dosimetry by the induced bromine activity and (CaF2 + Dy2O3 + KCl) and (CaSO4 + Dy2O3 + KCl) for thermal and epithermal neutron dosimetry by the induced dysprosium activity

  6. Development of the epithermal neutron beam and its clinical application for boron neutron capture therapy at the Brookhaven medical research reactor

    International Nuclear Information System (INIS)

    The failures of the Boron Neutron Capture Therapy (BNCT) trials conducted between 1951 and 1961 were attributed to inadequate penetration of the thermal neutron beams and poor localization of boron compound in the tumour. The epithermal neutron beam at the BMRR was designed and installed to improve the penetration of the neutron beam. The use of this epithermal neutron beam for the clinical trial initiated in 1994 at Brookhaven National Laboratory (BNL) was preceded by the neutron beam optimization and characterization, the validation of the treatment planning software and the establishment of a procedure for treatment plan evaluation and dose reporting and recording. To date, a total of 54 patients have been treated. Our experience in the development of the epithermal neutron beam for clinical BNCT at the BMRR may be useful to other investigators desirous of developing similar programs for cancer therapy. (author)

  7. Experimental evaluation of epithermal neutron self-shielding for 96Zr and 98Mo

    International Nuclear Information System (INIS)

    In a previous work we experimentally tested some neutron self-shielding calculations methods for thermal absorbers, from which the semi-empirical 'sigmoid method' gave the most accurate results. In this work we aim at evaluating the accuracy of this method on the epithermal self-shielding phenomena as compared to the analytical 'MatSSF method'. Metallic foils of Zr and Mo were compactly stacked together into small cylinders (or disks) of different thickness, allowing for up to 20 % epithermal self-shielding when irradiated on two channels of the BR1 reactor. A 2 % relative difference between calculated and experimental self-shielding factors was obtained from the MatSSF method when a perpendicular source-sample axial configuration was assumed, while the isotropic or the co-axial configuration alternatives gave up to 10 % relative differences. On the other hand, the sigmoid method gave relative differences of up to 6 % that can be reduced to just 2 % by applying the 'effective' epithermal absorption cross-sections for 98Mo and 96Zr proposed in this work. (author)

  8. Boron neutron capture therapy (BNCT) for glioblastoma multiforme using the epithermal neutron beam at the Brookhaven Medical Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Capala, J. [Brookhaven National Lab., Upton, NY (United States); Diaz, A.Z.; Chadha, M. [Univ. Hospital, State Univ. of New York, NY (United States)] [and others

    1997-12-31

    The abstract describes evaluation of boron neutron capture therapy (BNCT) for two groups of glioblastoma multiforme patients. From September 1994 to February 1996 15 patients have been treated. In September 1997 another 34 patients were examined. Authors determined a safe starting dose for BNCT using epithermal neutrons and BPA-F. They have also evaluated adverse effects of BNCT at this starting dose. Therapeutic effectiveness of this starting dose has been evaluated. No significant side effects from BPA-F infusion or BNCT treatment were observed in normal brains.

  9. Conceptual design of epithermal neutron beam for BNCT in the thermalizing column of TRIGA reactor

    International Nuclear Information System (INIS)

    The Monte Carlo feasibility study of development of the epithermal neutron beam for BNCT clinical trials in thermalising column (TC) of TRIGA reactor is presented. The investigation of the possible use of fission converter as well as the set-up of TRIGA reactor core is performed. The optimization of the irradiation facility components is carried out and the configuration with the most favorable cost/performance ratio is proposed. The results prove, that a BNCT irradiation facility with performances, comparable to existing beams throughout the world, could be installed in TC/DC of the TRIGA reactor, quite suitable for the clinical treatments of human patients.(author)

  10. Epithermal neutron activation analysis of Spirulina platensis biomass and extracted C-phycocianin and DNA

    International Nuclear Information System (INIS)

    Epithermal neutron activation analysis (ENAA) was used for study the biomass of Spirulina platensis. The background levels of concentration 27 macro-, micro- and trace elements ranging from 10-3 to 104 ppm was determined. It was found that the biomass of Spirulina does not contain toxic element concentrations above the tolerance level and can be utilized as a matrix of pharmaceuticals. The concentrations of basic elements in C-phycocianin and DNA extracted from Spirulina platensis were determined by ENAA. A comparison of the element content of a whole Spirulina biomass with that of a refined C-phycocianin preparation was made. (author)

  11. Epithermal neutron flux characterization of the TRIGA MARK II reactor, Ljubljana, Yugoslavia, for use in NAA

    International Nuclear Information System (INIS)

    The nonideality of the epithermal neutron flux distribution at a reactor site can be described by a 1/E1+α spectrum representation, with parameter α as a measure of nonideality. α-values were determined in 3 typical irradiation positions of the TRIGA MARK II reactor, Ljubljana, Yugoslavia, using the 'Cd-ratio for multi-monitor' method. The simpler 'Cd-ratio for dual monitor' method also yielded reliable results. This characterization is useful in the ko-method of NAA. (author) 18 refs.; 3 figs

  12. An evaluation of thermal and epithermal neutron activation analysis compton suppression methods for biological reference materials.

    Science.gov (United States)

    Landsberger, S; Wu, D

    1999-01-01

    For neutron activation analysis (NAA), the usual matrix problems of sodium, chlorine, and bromine are well known to give rise to high backgrounds that inhibit the determination of several trace elements for short-lived or medium-lived NAA. For long counting times in long-lived NAA, very low backgrounds are required to achieve good sensitivities. We have investigated the use of thermal and epithermal NAA in conjunction with Compton suppression to determine several elements such as arsenic, antimony, cadmium, and mercury, at the level of a few nanograms. The values of these techniques are discussed in contrast to the standard radiochemical methods. PMID:10676521

  13. The determination of uranium in food samples by Compton suppression epithermal neutron activation analysis.

    Science.gov (United States)

    Kapsimalis, R; Landsberger, S; Ahmed, Y A

    2009-12-01

    Eight foods common to the Nigerian diet were analyzed for trace amounts of uranium using epithermal neutron activation analysis. Food sample sizes of roughly one-half gram, irradiated for 10 min, with a 15 min decay time and counting time for 10 min yielded detection limits between 0.02 and 0.04 Bq/kg. Dried milk, chicken pasta, spaghetti and biscuits had less than detectable amounts of uranium, while sorghum, wheat and brown beans contained 0.73, 0.23 and 0.16 Bq/kg, respectively. PMID:19541492

  14. Nondestructive determination of arsenic in urine by epithermal neutron activation analysis and Compton suppression.

    Science.gov (United States)

    Landsberger, S; Swift, G; Neuhoff, J

    1990-01-01

    Epithermal neutron activation analysis, in conjunction with Compton suppression, has been employed to determine arsenic levels in artificially doped urine samples. Typical detection limits were of the order of 10 ng/g. Replicate determinations gave precision values between 2 and 12%, whereas accuracy measurements were between +/- 1 and +/- 20%. Biological and geological reference materials from the National Institute of Standards and Technology (NIST) were also analyzed for arsenic content. Typically, the precision achieved again was between 2 and 12%, whereas the accuracy measurements were in excellent agreement with the certified values. PMID:1704729

  15. Application of thermal and epithermal neutron activation analysis to rocks and sediment samples

    International Nuclear Information System (INIS)

    Neutron activation analysis (NAA) has been applied to the determination of several trace elements in rocks and in marine sediments. Epithermal neutron activation analysis (ENAA) has been shown to be useful in the analysis of rocks, because some strong activities limiting the instrumental determination of many elements are reduced. Some USGS geological reference materials have been activated by both thermal and epithermal neutrons, evaluating the experimental advantage factors of ENAA and comparing the obtained concentrations and the detection limits for both methods. ENAA is particularly useful to determine several elements, among which some of the rare earth elements (REE), whose importance in petrogenetic studies is well known. In the case of marine sediments, the REE are considered particularly important for simulating the chemical behaviour of the actinides in the environment. For this purpose, REE have been determined after a group separation from the matrix, in order reduce the complexity of the activation gamma-ray spectra. This separation step improves detection limits for all REE, allowing the determination of some of them not easily detected without a separation, like Nd, Gd, Tb, and Tm

  16. OPTIMIZATION OF THE EPITHERMAL NEUTRON BEAM FOR BORON NEUTRON CAPTURE THERAPY AT THE BROOKHAVEN MEDICAL RESEARCH REACTOR

    International Nuclear Information System (INIS)

    Clinical trials of Boron Neutron Capture Therapy for patients with malignant brain tumor had been carried out for half a decade, using an epithermal neutron beam at the Brookhaven's Medical Reactor. The decision to permanently close this reactor in 2000 cut short the efforts to implement a new conceptual design to optimize this beam in preparation for use with possible new protocols. Details of the conceptual design to produce a higher intensity, more forward-directed neutron beam with less contamination from gamma rays, fast and thermal neutrons are presented here for their potential applicability to other reactor facilities. Monte Carlo calculations were used to predict the flux and absorbed dose produced by the proposed design. The results were benchmarked by the dose rate and flux measurements taken at the facility then in use

  17. The alanine detector in BNCT dosimetry: Dose response in thermal and epithermal neutron fields

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, T., E-mail: schmito@uni-mainz.de [Institute for nuclear chemistry, Johannes Gutenberg-University, Mainz D-55128 (Germany); Bassler, N. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, Aarhus C, Aarhus 8000 (Denmark); Blaickner, M. [AIT Austrian Institute of Technology GmbH, Vienna A-1220 (Austria); Ziegner, M. [AIT Austrian Institute of Technology GmbH, Vienna A-1220, Austria and TU Wien, Vienna University of Technology, Vienna A-1020 (Austria); Hsiao, M. C. [Insitute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liu, Y. H. [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Koivunoro, H. [Department of Physics, University of Helsinki, POB 64, FI-00014, Finland and HUS Medical Imaging Center, Helsinki University Central Hospital, FI-00029 HUS (Finland); Auterinen, I.; Serén, T.; Kotiluoto, P. [VTT Technical Research Centre of Finland, Espoo (Finland); Palmans, H. [National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW, United Kingdom and Medical Physics Group, EBG MedAustron GmbH, Wiener Neustadt A-2700 (Austria); Sharpe, P. [National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW (United Kingdom); Langguth, P. [Department of Pharmacy and Toxicology, University of Mainz, Mainz D-55128 (Germany); Hampel, G. [Institut für Kernchemie, Johannes Gutenberg-Universität, Mainz D-55128 (Germany)

    2015-01-15

    Purpose: The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Methods: Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secondary particle spectra. Further irradiations have been made in the epithermal neutron beams at the research reactors FiR 1 in Helsinki, Finland, and Tsing Hua open pool reactor in HsinChu, Taiwan ROC. Readout has been performed with electron spin resonance spectrometry with reference to an absorbed dose standard in a {sup 60}Co gamma ray beam. Absorbed doses and dose components have been calculated using the Monte Carlo codes FLUKA and MCNP. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using the Hansen and Olsen alanine response model. Results: The measured dose response of the alanine detector in the different experiments has been evaluated and compared to model predictions. Therefore, a relative effectiveness has been calculated for each dose component, accounting for its dependence on particle type and energy. Agreement within 5% between model and measurement has been achieved for most irradiated detectors. Significant differences have been observed in response behavior between thermal and epithermal neutron fields, especially regarding dose composition and depth dose curves. The calculated dose components could be verified with the experimental results in the different primary and secondary particle fields. Conclusions: The

  18. Design of epithermal neutron beam for clinical BNCT treatment at Slovenian TRIGA research reactor

    International Nuclear Information System (INIS)

    The Monte Carlo feasibility study of development of epithermal neutron beam for BNCT clinical trials on Jozef Stefan Institute (JSI) TRIGA reactor is presented. The investigation of the possible use of fission converter for the purpose of enhancement of neutron beam, as well as the set-up of TRIGA reactor core is performed. The optimization of the irradiation facility components is carried out and the configuration with the most favorable cost/performance ratio is proposed. The simulation results prove that a BNCT irradiation facility with performances, comparable to existing beams throughout the world, could be installed in the thermalizing column of the TRIGA reactor, quite suitable for the clinical treatments of human patients. (author)

  19. Measurement of the epithermal neutron flux of the Argonauta reactor by the Sandwich method

    International Nuclear Information System (INIS)

    A common method of obtaining information about the neutron spectrum in the energy range of 1 eV to a few keV is by using resonance sandwich detectors. A sandwich detector is usually made up of three foils placed one on top of the other, each having the same thickness and being made of the same material which has a pronounced absorption resonance. To make an adequate evaluation, the sandwich method was compared with one using an isolated detector. The results obtained from approximate theoretical calculations were checked experimentally, using In, Au and Mn foils, in an isotropic 1/E flux in the Argonaut Reactor at I.E.N. As practical application of this method, the deviation from a 1/E spectrum of the epithermal neutron flux in the core and external graphite reflector of the Argonaut Reactor has been measured with the sandwich foils previously calibrated in a 1/E spectrum. (author)

  20. Design of epithermal neutron beam for clinical BNCT treatment at Slovenian TRIGA research reactor

    Energy Technology Data Exchange (ETDEWEB)

    Maucec, Marko [Jozef Stefan Institute, Reactor Physics Division, Lubljana (Slovenia). E-mail: marko.mauce@ijs.si

    1999-07-01

    The Monte Carlo feasibility study of development of epithermal neutron beam for BNCT clinical trials on Jozef Stefan Institute (JSI) TRIGA reactor is presented. The investigation of the possible use of fission converter for the purpose of enhancement of neutron beam, as well as the set-up of TRIGA reactor core is performed. The optimization of the irradiation facility components is carried out and the configuration with the most favorable cost/performance ratio is proposed. The simulation results prove that a BNCT irradiation facility with performances, comparable to existing beams throughout the world, could be installed in the thermalizing column of the TRIGA reactor, quite suitable for the clinical treatments of human patients. (author)

  1. Epithermal neutron activation analysis of blue-green algae Spirulina Platensis as a matrix for selenium-containing pharmaceuticals

    International Nuclear Information System (INIS)

    To evaluate the potentiality of the blue-green algae Spirulina Platensis as a matrix for the production of Se-containing pharmaceuticals, the background levels of 31 major, minor and trace elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni (using (n,p)-reaction), As, Br, Zn, Rb, Mo, Ag, Sb, I, Ba, Sm, Tb, Tm, Hf, Ta, W, Au, Hg, Th) in Spirulina Platensis biomass were determined by means of epithermal neutron activation analysis. The possibility of the purpose-oriented incorporation of Se into Spirulina Platensis biomass was demonstrated. The polynomial dependence of the Se accumulation on nutritional medium loading was revealed. The employed analytical technique allows one to reliably control the amount of toxic elements in algae Spirulina Platensis. Based on this study, a conclusion of the possibility to use Spirulina Platensis as a matrix for the production of Se-containing pharmaceuticals was drawn

  2. α - Determination in the E-(1+α) epithermal neutron spectrum in TRIGA 14 MW reactor

    International Nuclear Information System (INIS)

    For experimental determination of the α parameter in the irradiation channels of the TRIGA 14MW reactor (at INR Pitesti) the two-detector method has been applied. The two-detector method was modified by using Cd ratio measurements to avoid the systematic errors introduced due to the inaccuracy of absolute nuclear data. This characterization of the epithermal neutron spectrum is used in the k0-method of NAA, implemented at the INR Pitesti. Neutron spectrum parameters as determined in the inner irradiation channel XC-1, are: α = 0.0343±0.002 and f = 22.5±0.5. For an outer irradiation channel, Beryllium J-6, we also have found the following neutron spectrum parameters α = -0.04046±0.003 and f 17.73±0.3; for Beryllium J-7 channel α = -0.02187±0.0025 and f 15.33±0.5 and for outer irradiation channel K-11 the neutron spectrum parameters are α = 0.0162±0.002 and f = 48.63±0.5 respectively. (authors)

  3. Effective dose evaluation for BNCT treatment in the epithermal neutron beam at THOR

    International Nuclear Information System (INIS)

    This paper aims to evaluate the effective dose as well as equivalent doses of several organs of an adult hermaphrodite mathematical phantom according to the definition of ICRP Publication 60 for BNCT treatments of brain tumors in the epithermal neutron beam at THOR. The MCNP5 Monte Carlo code was used for the calculation of the average absorbed dose of each organ. The effective doses for a typical brain tumor treatment with a tumor treatment dose of 20 Gy-eq were evaluated to be 0.59 and 0.35 Sv for the LLAT and TOP irradiation geometries, respectively. In addition to the stochastic effect, it was found that it is also likely to produce deterministic effects, such as cataracts and depression of haematopoiesis.

  4. Measurement of thermal, epithermal and fast neutron flux in the IEA-R1 reactor by the foil activation method

    International Nuclear Information System (INIS)

    Experimental and theoretical details of the foil activation method applied to neutrons flux measurements at the IEA-R1 reactor are presented. The thermal - and epithermal - neutron flux were determined form activation measurements of gold, cobalt and manganese foils; and for the fast neutron flux determination, aluminum, iron and nickel foils were used. The measurements of the activity induced in the metal foils were performed using a Ge-Li gamma spectrometry system. In each energy range of the reactor neutron spectrum, the agreement among the experimental flux values obtained using the three kind of materials, indicates the consistency of the theoretical approach and of the nuclear parameters selected. (Author)

  5. Physics design for the Brookhaven Medical Research Reactor epithermal neutron source

    International Nuclear Information System (INIS)

    A collaborative effort by researchers at the Idaho National Engineering Laboratory and the Brookhaven National Laboratory has resulted in the design and implementation of an epithermal-neutron source at the Brookhaven Medical Research Reactor (BMRR). Large aluminum containers, filled with aluminum oxide tiles and aluminum spacers, were tailored to pre-existing compartments on the animal side of the reactor facility. A layer of cadmium was used to minimize the thermal-neutron component. Additional bismuth was added to the pre-existing bismuth shield to minimize the gamma component of the beam. Lead was also added to reduce gamma streaming around the bismuth. The physics design methods are outlined in this paper. Information available to date shows close agreement between calculated and measured beam parameters. The neutron spectrum is predominantly in the intermediate energy range (0.5 eV - 10 keV). The peak flux intensity is 6.4E + 12 n/(m2.s.MW) at the center of the beam on the outer surface of the final gamma shield. The corresponding neutron current is 3.8E + 12 n/(m2.s.MW). Presently, the core operates at a maximum of 3 MW. The fast-neutron KERMA is 3.6E-15 cGy/(n/m2) and the gamma KERMA is 5.0E-16 cGY/(n/m2) for the unperturbed beam. The neutron intensity falls off rapidly with distance from the outer shield and the thermal flux realized in phantom or tissue is strongly dependent on the beam-delimiter and target geometry

  6. The specific purpose Monte Carlo code McENL for simulating the response of epithermal neutron lifetime well logging tools

    International Nuclear Information System (INIS)

    A new specific purpose Monte Carlo code called McENL for modeling the time response of epithermal neutron lifetime tools is described. The code was developed so that the Monte Carlo neophyte can easily use it. A minimum amount of input preparation is required and specified fixed values of the parameters used to control the code operation can be used. The weight windows technique, employing splitting and Russian Roulette, is used with an automated importance function based on the solution of an adjoint diffusion model to improve the code efficiency. Complete composition and density correlated sampling is also included in the code and can be used to study the effect on tool response of small variations in the formation, borehole, or logging tool composition and density. An illustration of the latter application is given here for the density of a thermal neutron filter. McENL was benchmarked against test-pit data for the Mobil pulsed neutron porosity (PNP) tool and found to be very accurate. Results of the experimental validation and details of code performance are presented

  7. Large animal normal tissue tolerance using an epithermal neutron beam and borocaptate sodium

    International Nuclear Information System (INIS)

    Irradiation of the canine head following intravenous Na2B12H11SH (BSH) administration has provided useful information concerning the tolerance of skin and brain to the resultant complex form of irradiation. The effect of the boron capture reaction in skin and brain has provided estimates of the influence of the microscopic dosimetry involved. Dogs irradiated with the epithermal bam alone provided valuable insight into the relative biological effectiveness (RBE) of the fast neutron component (>10 keV) of the epithermal beam. When comapred with literature values for X-rays for the occurrence of skin necrosis in dogs, an RBE of 4.5 was derived. Previous pharmacokinetic data concerning the distribution of Na2B12H11SH (BSH) to blood and bran has been used to obtain input parameters for computer models of the microvasculature of the brain. Monte Carlo computer models were used to simulate the microscopic distribution of BSH in the normal brain. The term compo- und factor describes the product of the microscopic boron fission fragment dose hitting the nucleus and the relative biologic effectiveness divided by the macroscopic equilibrium dose of the boron reaction in the tissue of interest. The computed compound factor for Na2B12H11SH (BSH) in normal brain was 0.37. This factor agreed very well with the value of 0.32 obtained for the brain necrosis with the dog irradiations. The compound factor for the dog's skin was experimentally derived from the dog experiments and was equal to 0.5. (orig.)

  8. Determination of Uranium and Thorium in Brazilian coals by epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    An experimental technique for the determination of uranium and thorium in coal by epithermal neutron activation was developed and systemized. Seventeen different coal samples, six copper monitors for neutron flux corrections and three NBS standard coal samples were irradiated together in a cadmium cylinder. Uranium and thorium were determined by measuring the 239N sub(p) and 233P sub(a) activities respectively, being both produced in (n,γ) reactions and subsequent β- decay. The 239N sub(p) was measured by counting the 106.4 KeV γ-ray in a LEPS detector and the 233P sub(a) by counting the 311.8 KeV γ-ray, but in a Ge(Li) detector. A 4096 multichannel analizer and a PDP-11 computer complemented the basic measuring equipment. An average precision of 3% was obtained in the analysis of seventeen coal samples coming from different strata and heights of Charqueadas and Morungava mines in Rio Grande do Sul State. The sensitivity of the method is around 100 ppb. This technique will allow determinations of up to twenty elements, besides uranium and thorium, and it can be applied in routine analysis. (Author)

  9. Depth-dose evaluation for lung and pancreas cancer treatment by BNCT using an epithermal neutron beam

    International Nuclear Information System (INIS)

    The depth-dose distributions were evaluated for possible treatment of both lung and pancreas cancers using an epithermal neutron beam. The MCNP calculations showed that physical dose in tumors were 6 and 7 Gy/h, respectively, for lung and pancreas, attaining an epithermal neutron flux of 5x108 ncm-2s-1. The boron concentrations were assumed at 100 ppm and 30 ppm, respectively, for lung and pancreas tumors and normal tissues contains 1/10 tumor concentrations. The dose ratios of tumor to normal tissue were 2.5 and 2.4, respectively, for lung and pancreas. The dose evaluation suggests that BNCT could be applied for both lung and pancreas cancer treatment. (author)

  10. Dependence of the Ratio between the Resonance Integral and Thermal Neutron Cross Section on the Deviation of the Epithermal Neutron Spectrum from the 1/E Law

    International Nuclear Information System (INIS)

    In k0- Neutron Activation Analysis (k0-NAA), the conversion from the tabulated Q0 (ratio of the resonance integral to thermal neutron cross-section)to Q0(α) (α is the shape factor of the epithermal neutron flux, indicating the deviation of the epithermal neutron spectrum from the ideal 1/E shape) are calculated using a FORTRAN program. The calculations are done for most elements that can be detected by neutron activation using different values of the parameter (α) ranging from -0.1≤α≤+0.1. The obtained data are used to study the dependence of the values (α) on the irradiation position factor in (k0-NAA)equation for some selected isotopes differ in their resonance energy and its Q0 values. The results show that, the irradiation factor is affective mainly for low thermal tro epithermal flux ratio f especially for Q0 value greater than 50. so consequently determining the irradiation parameters α value is not needed for irradiation positions that rich with thermal neutron. But for high f values the irradiation position factor should be taken into account. On the other hand the constructed FORTRAN program can be used to calculate the value Q0 (α) directly for different value of α

  11. Epithermal neutron activation analysis of CR(VI)-reducer basalt-inhabiting bacteria

    International Nuclear Information System (INIS)

    Epithermal neutron activation analysis (ENAA) has been applied to studying elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance (ESR) demonstrating that the bacteria differ in the rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(VI) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 μg/g of dry weight) indicate bacterial adaptation to the environmental conditions typical of the basalts. The concentrations of at least 12-19 different elements ranging from major- to ultratrace ones were determined in each type of bacteria simultaneously. The range of concentrations spans over 8 orders of magnitude

  12. Epithermal Neutron Activation Analysis (ENAA) of Cr(VI)-reducer Basalt-inhabiting Bacteria

    CERN Document Server

    Tsibakhashvili, N Ya; Kirkesali, E I; Aksenova, N G; Kalabegishvili, T L; Murusidze, I G; Mosulishvili, L M; Holman, H Y N

    2005-01-01

    Epithermal neutron activation analysis (ENAA) has been applied to studying elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance (ESR) demonstrating that the bacteria differ in the rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(V) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 $\\mu $g/g of dry weight) indicate bacterial adaptation to the environmental condition...

  13. Marine gradients of halogens in moss studied by epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    Epithermal neutron activation analysis is known to be a powerful technique for the simultaneous study of chlorine, bromine and iodine in environmental samples. It is shown to be useful to elucidate marine gradients of these elements. Examples are from a transect study in northern Norway where samples of the feather moss Hylocomium splendens were collected at distances 0-300 km from the coastline. All three elements decreased exponentially as a function of distance from the ocean in the moss samples, strongly indicating that atmospheric supply from the marine environment is the predominant source of these elements to the terrestrial ecosystem. These results are compared with similar data for surface soils along the same gradients. Comparison is also made with previous data for halogens in moss in Norway obtained by conventional NAA and covering similar transects in other geographical regions. The Cl/Br and Br/I ratios in moss showed a regular change distance from the ocean in all transects, and hypotheses for this behaviour are presented

  14. Environmental monitoring for uranium and neptunium at Yucca Mountain using Epithermal Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Epithermal Neutron Activation Analysis (ENAA) is investigated as an analysis method for uranium and neptunium in environmental samples from Yucca Mountain. The design and construction of a facility for this technique are described. Theoretical improvement in sensitivity for ENAA over thermal NAA (TNAA) is discussed and compared to experimental results for different sample types. Uranium is analyzed in eight different sample matrices, including samples from Yucca Mountain. Neptunium has been studied only in AGV-1 Granite. As predicted by theory, uranium shows a high experimental sensitivity improvement factor (average = 7.76), while neptunium has a factor of only 0.49. Detection limits for uranium using ENAA range from 6 to 52 ppb by weight (2.6 to 17 ng in sample) for the different matrices. Neptunium shows a detection limit of 57 ppb by weight (6.2 ng in sample) in AGV-1 Granite using ENAA. Using TNAA, neptunium can be analyzed to 35 ppB by weight (3.4 ng in sample)

  15. Marine Gradients of Halogens in Moss Studied by Epithermal Neutron Activation Analysis

    CERN Document Server

    Frontasyeva, M V

    2002-01-01

    Epithermal neutron activation analysis is known to be a powerful technique for the simultaneous study of chlorine, bromine and iodine in environmental samples. In this paper it is shown to be useful to elucidate marine gradients of these elements. Examples are from a transect study in northern Norway where samples of the feather moss Hylocomium splendens were collected at distances 0-300 km from the coastline. All three elements decreased exponentially as a function of distance from the ocean in the moss samples, strongly indicating that atmospheric supply from the marine environment is the predominant source of these elements to the terrestrial ecosystem. These results are compared with similar data for surface soils along the same gradients. Comparison is also made with previous data for halogens in moss in Norway obtained by conventional NAA and covering similar transects in other geographical regions. The Cl/Br and Br/I ratios in moss showed a regular change distance from the ocean in all transects, and h...

  16. Determination of iodine species in cow milk by preconcentration epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    Iodine is an essential trace element for human beings. The main source of iodine is generally food items such as fish and milk. Either the lack or the excess of iodine can cause health problems. Iodine deficiency disorder is fairly common in many countries of Africa and Asia. There exists an increasing interest in the determination of total iodine as well as various species of iodine in milk. We have developed an epithermal neutron activation analysis method with a Compton suppression (ENAA-CS) counting system for the determination of ppb levels of iodine. We have also employed chemical separation methods prior to ENAA-CS to measure the species-specific concentrations of iodine in cow milk. We have measured the following iodine concentrations in homogenized milk (3.25% milk fat): 0.475 ± 0.005 mg mL-1 of total iodine, 0.333 ± 0.003 mg mL-1 iodide, 0.06 ± 0.05 mg mL-1 iodate, 0.013 ± 0.003 mg mL-1 of lipid-bound iodine, and 0.032 ± 0.002 mg mL-1 protein-bound iodine. (author)

  17. Determination of uranium in human head hair of a Brazilian populational group by epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    Hair analysis is extensively used in forensic sciences, assessment of occupational or environmental exposure and in some cases also for clinical and nutritional studies. Hair has a series of advantages in relation to other biomonitors, like blood and urine, since it is very easy to collect, very stable at room temperature and it represents not only instantaneous concentrations, but it can reveal the exposure along a given period of time. The assessment of environmental or occupational exposure to uranium is generally done by means of urine analysis, although a few papers have described attempts to use hair as a biomonitor. In the present work, epithermal neutron activation analysis has been used to establish base-line concentrations for a Brazilian populational group, living in Sao Paulo and not exposed to uranium, either environmentally or occupationally. For quality control, the reference materials Pine Needles NIST 1575 and Basalt USGS BCR-1 were used. The concentrations obtained for the control population studied up to now varied from about 2 to 50 ng x g-1. (author)

  18. Electron Beam Tests of a High-Power Liquid-Lithium Target as an Intense Epithermal Neutron Source

    International Nuclear Information System (INIS)

    A prototype of a compact Liquid Lithium Target (L iL iT ), which will be able to constitute an accelerator-based intense neutron source with possible application for boron neutron capture therapy (BNCT) in hospitals, was built and tested with high power electron gun at Soreq Nuclear Research Center (SNRC). The lithium target will produce neutrons through the Li(p,n) Be reaction and it will overcome the major problem of removing the thermal power generated by a high-intensity proton beam (1.91-2.5 MeV, >3 mA), necessary for sufficient therapeutic neutron flux. The optimization of the neutron flux and energy spectrum for the maximum benefit to the therapy of deep-seated tumors has been studied in the last fifteen years . High neutron flux of 109cm-2 s- 1 at an irradiation facility beam port and epithermal neutrons energy, lying in the energy range 0.5 eV< E<10 keV, have been assessed as best suited for therapy of such tumors for a reasonable therapy duration (30-90 min(2)). Worldwide efforts to design a neutron converter for an accelerator-based BNCT facility, which might be more compatible with clinical environment (in hospital), have been focused on the use of lithium through the reaction Li(p,n) Be at proton energies of 1.9-2.5 MeV. The major advantage of this reaction consists in its low-energy neutron spectrum (mean neutron energy in the range of 30-300 keV). Despite the excellent neutronic qualities of the 7Li(p,n)7Be reaction, a reliable lithium target, working under beam power levels considered for therapy purpose (at least 3 mA, ∼2 MeV protons), has been considered as very difficult to build because of the mechanical, chemical and thermal properties of lithium (low melting point of 180 deg. C and low thermal conductivity of 85 W /(m K) at 300 K), the major problem being to remove the thermal power generated by the high-intensity proton beam. For such high intensity beam a solid lithium target would be destroyed by heat deposited in the target unless

  19. In-phantom characterisation studies at the Birmingham Accelerator-Generated epIthermal Neutron Source (BAGINS) BNCT facility.

    Science.gov (United States)

    Culbertson, Christopher N; Green, Stuart; Mason, Anna J; Picton, David; Baugh, Gareth; Hugtenburg, Richard P; Yin, Zaizhe; Scott, Malcolm C; Nelson, John M

    2004-11-01

    A broad experimental campaign to validate the final epithermal neutron beam design for the BNCT facility constructed at the University of Birmingham concluded in November 2003. The final moderator and facility designs are overviewed briefly, followed by a summary of the dosimetric methods and presentation of a small subset of the results from this campaign. The dual ionisation chamber technique was used together with foil activation to quantify the fast neutron, photon, and thermal neutron beam dose components in a large rectangular phantom exposed to the beam with a 12 cm diameter beam delimiter in place. After application of a normalisation factor, dose measurements agree with in-phantom MCNP4C predictions within 10% for the photon dose, within 10% for thermal neutron dose, and within 25% for the proton recoil dose along the main beam axis. PMID:15308136

  20. Design calculations of an epithermal neutron beam and development of a treatment planning system for the renovation of thor for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Tsing Hua University was recently granted by National Science Council a five-year project to renovate its Open-Pool reactor (THOR) for boron neutron capture therapy. With this support, the whole graphite blocks in the original thermal column region can be removed for redesigning and constructing a better epithermal neutron beam. THOR is a 1 MW research reactor. The cross section area of the core facing the thermal column is 60 cm x 50 cm. By using 60 cm FLUENTAL plus 10 cm Pb, with cross section area of 70 cm x 60 cm and surrounded by 6 cm thick PbF2 reflector, the epithermal neutron flux at the filter/moderator exit can reach ∼8.5 x 109 n/cm2/s. When the collimator is added, the epithermal neutron beam intensity at the beam exit is reduced to 3 x 109 n/cm2/sec, but is still six times higher than the previous beam. Facing the clinical trials scheduled 3 and half years from now, a preliminary version of treatment planning system is developed. It includes a pre-processor to read CT scan and post-processors to display dose distributions. (author)

  1. FORM-OTA, Multigroup Constant for Epithermal Neutron Slowing-Down in Homogeneous Media

    International Nuclear Information System (INIS)

    1 - Description of problem or function: FORM-OTA performs a multi- group slowing down calculation for a fundamental mode of given buckling in a homogeneous medium to obtain space-independent energy spectra for the epithermal neutron flux and current. Using the calculated flux and current spectra the program produces group constants for desired few group schemes. 2 - Method of solution: FORM-OTA is a member of the MUFT family of programs. The one-dimensional transport equation for the flux in plane geometry is solved by removing the spatial dependence by a Fourier transformation and by treating the angular dependence in either B1- or P1-approximation. Elastic slowing-down by hydrogen can be solved in an exact manner using a differential equation formulation. Elastic slowing-down by all non-hydrogen elements is lumped together and treated in the Greuling-Goertzel approximation. For resonance absorption a rather simple formulation is used. A flux peaking in the fuel can be assessed, too. The energy group structure (54 groups in the range 10 MeV - .625 eV) is pre-programmed into the code. A facility is provided to modify library data and to introduce entirely new data at run-time. 3 - Restrictions on the complexity of the problem: Maximum 18 elements (isotopes) in a mixture. Of these 18 elements maximum 10 elements can have resonance data. Maximum 6 few group schemes. Maximum 25 group in any few group scheme. Maximum 25 groups in a heterogeneous two-region (fuel-moderator) calculation

  2. Intraoperative boron neutron capture therapy for malignant gliomas. First clinical results of Tsukuba phase I/II trial using JAERI mixed thermal-epithermal beam

    International Nuclear Information System (INIS)

    Since October 1999, a clinical trial of intraoperative boron neutron capture therapy (IOBNCT) is in progress at JRR-4 (Japan Research Reactor-4) in Japan Atomic Energy Research Institute (JAERI) using mixed thermal-epithermal beam (thermal neutron beam I: TNB-I). Compared to pure thermal beam (thermal neutron beam II: TNB-II), TNB-I has an improved neutron delivery into the deep region than TNB-II. The clinical protocol and the preliminary results will be discussed. (author)

  3. Determination of iodine species in cow milk by preconcentration epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    Full text: Iodine is an essential trace element for human beings. The main source of iodine is generally food items such as fish and milk. Either the lack or the excess of iodine can cause health problems. Iodine deficiency disorder is fairly common in many countries of Africa and Asia. There exists an increasing interest in the determination of total iodine as well as various species of iodine in milk. One of the problems in the analysis of iodine is the lack of highly sensitive methods. Neutron Activation Analysis (NAA) is one of the techniques, particularly when the irradiation is done using epithermal neutrons which is called ENAA, that can provide low detection limits. These limits can be further improved when ENAA is used in conjunction with an anti-coincidence (ENAA-AC) counting system. We have developed an ENAA-AC method for the determination of ppb levels of iodine. We have also employed chemical separation methods prior to ENAA-AC to measure the species-specific concentrations of iodine in cow milk. We have separated lipid-bound iodine using solvent extraction followed by further fractionation using a silica gel column. We have used ammonium sulfate precipitation to separate protein-bound iodine. We precipitated whole casein-bound iodine at pH=4.6. We separated the inorganic species, such as iodide and iodate, using ion exchange chromatography. We have measured the following iodine concentrations in homogenized milk (milk fat 3.25%): 0.475±0.005 μg mL-1 of total iodine, 0.432 ±0.003 μg mL-1 iodide, 0.016±0.005 μg mL-1 iodate, 0.013±0.003 μg mL-1 of lipid-bound iodine, 0.032±0.002 μg mL-1 protein-bound iodine, and 0.026±0.001 μg mL-1 casein-bound iodine. We have observed that ENAA-AC is a powerful technique for the determination of iodine and its species when used in conjunction with chemical separation methods. The detection limits are low and the precision and accuracy are high. (author)

  4. Application of epithermal neutron activation analysis to investigate accumulation and adsorption of mercury by Spirulina platensis biomass

    International Nuclear Information System (INIS)

    Epithermal neutron activation analysis was used to study interaction of blue-green alga Spirulina platensis with toxic metal mercury. Various concentrations of Hg(II) were added to cell cultures in a nutrient medium. The dynamics of accumulation of Hg was investigated over several days in relation to Spirulina biomass growth. The process of Hg adsorption by Spirulina biomass was studied in short-time experiments. The isotherm of adsorption was carried out in Freindlich coordinates. Natural Spirulina biomass has potential to be used in the remediation of sewage waters at Hg concentrations ∼100 μg/1

  5. Dose imaging in a thorax phantom with lung-equivalent volume at the epithermal neutron beam of LVR-15 reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G. [Department of Physics, University of Milan (Italy); INFN-National Institute of Nuclear Physics, Division of Milan (Italy)], E-mail: grazia.gambarini@mi.infn.it; Vanossi, E. [Department of Energy, Polytechnic of Milan (Italy); INFN-National Institute of Nuclear Physics, Division of Milan (Italy); Bartesaghi, G. [Department of Physics, University of Milan (Italy); INFN-National Institute of Nuclear Physics, Division of Milan (Italy); Carrara, M. [Fondazione IRCCS ' Istituto Nazionale Tumori' , Milan (Italy); Mariani, M. [Department of Energy, Polytechnic of Milan (Italy); Negri, A. [Department of Physics, University of Milan (Italy); INFN-National Institute of Nuclear Physics, Division of Milan (Italy); Burian, J.; Viererbl, L.; Klupak, V.; Rejchrt, J. [Department of Reactor Physics, NRI Rez, plc (Czech Republic)

    2009-07-15

    A thorax phantom has been designed, consisting of PMMA and PE plates containing a cavity filled with a laboratory-made lung-substitute. Fricke-gel dosimeters have been placed in the lung-substitute volume, and the phantom has been irradiated at the epithermal column of LVR-15 reactor. Absorbed dose images have been obtained for both gamma radiation and charged particles emitted in the {sup 10}B reactions with thermal neutrons. Measurements with thermoluminescence dosimeters (TLDs) and Monte Carlo (MC) calculations have been performed too, in order to attain inter-comparison of results.

  6. Application of Epithermal Neutron Activation Analysis to Investigate Accumulation and Adsorption of Mercury by Spirulina platensis Biomass

    CERN Document Server

    Mosulishvili, L M; Khizanishvili, A I; Frontasyeva, M V; Kirkesali, E I; Aksenova, N G

    2004-01-01

    Epithermal neutron activation analysis was used to study interaction of blue-green alga Spirulina platensis with toxic metal mercury. Various concentrations of Hg(II) were added to cell cultures in a nutrient medium. The dynamics of accumulation of Hg was investigated over several days in relation to Spirulina biomass growth. The process of Hg adsorption by Spirulina biomass was studied in short-time experiments. The isotherm of adsorption was carried out in Freindlich coordinates. Natural Spirulina biomass has potential to be used in the remediation of sewage waters at Hg concentrations \\sim 100 {\\mu}g/l.

  7. Design, construction and installation of an epithermal neutron beam for BNCT at the High Flux Reactor Petten

    International Nuclear Information System (INIS)

    Following the formation in 1987, of both the European Collaboration group on Boron Neutron Capture Therapy (BNCT) and the Petten BNCT group, steps were taken to design and implement an epithermal neutron beam for BNCT applications at the High Flux Reactor (HFR) at Petten. The installation would serve as a European facility, while once the modality of BNCT is proven would be the pathfinder for implementation of BNCT at other European nuclear sites. Due to its favorable nuclear and geometric characteristics, the beam tube HB11 was chosen as the candidate beam tube for BNCT applications. To reconfigure the beam tube to produce the required epithermal neutrons, it was first necessary to remove the existing mirror system and then to install the appropriate filter materials. Due to the fixed operating schedule of the HFR, with only one long shut-down period per year during the summer weeks for maintenance and upgrading actions, installation of the new facility was planned for the summer stop period in 1990

  8. Simulation study of the photon quality correction factors of ionization chambers for FiR 1 epithermal neutron beam

    International Nuclear Information System (INIS)

    At FiR 1 BNCT facility in Finland, neutron-insensitive Mg(Ar) ionization chambers are used for photon dose measurements in an epithermal neutron beam. Previously, photon sensitivity factors for the chamber for the measurements in a water phantom in FiR 1 beam have been determined experimentally from measurements in 60Co gamma and in a 6 MV clinical accelerator photon beams. However, the response of the ionization chamber in a water phantom depends on energy spectrum and angle of the photons and the secondary electrons created inside the phantom and may differ depending on type of the irradiation source (accelerator vs. an epithermal neutron beam). Also, the experimental sensitivity factor does not take into account the possible perturbations in the photon production in phantom caused by the ionization chamber materials. Therefore, it is necessary to determine the photon quality correction factors (kQγ) for the Mg(Ar) chamber at the FiR 1 beam through computer simulations. In this study, the kQγ factors have been determined for Mg(Ar) chamber from Monte Carlo calculations of absorbed photon dose at two depths in a water phantom using MCNP code. The kqγ factors obtained with this method are compared to the sensitivity factors determined with measurements in an accelerator photon beam and to the kQγ factors published previously. (author)

  9. In phantom figures of merit for an epithermal beam produced by a D-D compact neutron generator

    International Nuclear Information System (INIS)

    Recently the BNCT (Boron Neutron Capture Therapy) Scientific Community renewed the interest in the development of compact neutron sources for in hospital BNCT in order to skip the problems related to the use of nuclear reactors and to increase the number of treated patients. This paper presents a feasibility study for the exploitation of a high power D-D compact neutron facility, designed at Lawrence Berkeley National Laboratory (Ca, USA), for the treatment of tumours with diffuse metastases, such as liver cancer. The MCNP code is used to carry out an accurate study of the epithermal column and to assess both the free beam parameters and the in phantom figures of merit to evaluate the beam effectiveness. Various Beam Shaping Assemblies are tested using different materials and geometrical shapes in order to optimize the therapeutic ratio. Finally, the dose profiles are calculated along the beam axis in the anthropomorphic phantom 'ADAM'. (author)

  10. Thermal and epithermal neutron fluence rate gradient measurements by PADC detectors in LINAC radiotherapy treatments-field

    International Nuclear Information System (INIS)

    LINAC VARIAN 2100 is where energetic electrons produce Bremsstrahlung radiation, with energies above the nucleon binding energy (E≈5.5MeV). This radiation induce (γ,n) and (e,e’n) reactions mainly in the natural tungsten target material (its total photoneutron cross section is about 4000 mb in a energy range from 9-17 MeV). These reactions may occur also in other components of the system (e.g. multi leaf collimator). During radiation treatment the human body may receive an additional dose inside and outside the treated volume produced by the mentioned nuclear reactions. We measured the neutron density at the treatment table using nuclear track detectors (PADC-NTD). These covered by a boron-converter are employed, including a cadmium filter, to determine the ratio between two groups of neutron energy, i.e. thermal and epithermal. The PADC-NTD detectors were exposed to the radiation field at the iso-center during regular operation of the accelerator. Neutron are determined indirectly by the converting reaction 10B(n,α)7Li the emerging charged particle leave their kinetic energy in the PADC forming a latent nuclear track, enlarged by chemical etching (6N, NaOH, 70°C). Track density provides information on the neutron density through calibration coefficient (∼1.6 104 neutrons /track) obtained by a californium source. We report the estimation of the thermal and epithermal neutron field and its gradient for photoneutrons produced in radiotherapy treatments with 18 MV linear accelerators. It was obsered that photoneutron production have higher rate at the iso-center

  11. Thermal and epithermal neutron fluence rate gradient measurements by PADC detectors in LINAC radiotherapy treatments-field

    Energy Technology Data Exchange (ETDEWEB)

    Barrera, M. T., E-mail: mariate9590@gmail.com; Barros, H.; Pino, F.; Sajo-Bohus, L. [Universidad Simón Bolívar, Nuclear Physics Laboratory, Sartenejas, Caracas (Venezuela, Bolivarian Republic of); Dávila, J. [Física Médica C. A. and Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of)

    2015-07-23

    LINAC VARIAN 2100 is where energetic electrons produce Bremsstrahlung radiation, with energies above the nucleon binding energy (E≈5.5MeV). This radiation induce (γ,n) and (e,e’n) reactions mainly in the natural tungsten target material (its total photoneutron cross section is about 4000 mb in a energy range from 9-17 MeV). These reactions may occur also in other components of the system (e.g. multi leaf collimator). During radiation treatment the human body may receive an additional dose inside and outside the treated volume produced by the mentioned nuclear reactions. We measured the neutron density at the treatment table using nuclear track detectors (PADC-NTD). These covered by a boron-converter are employed, including a cadmium filter, to determine the ratio between two groups of neutron energy, i.e. thermal and epithermal. The PADC-NTD detectors were exposed to the radiation field at the iso-center during regular operation of the accelerator. Neutron are determined indirectly by the converting reaction {sup 10}B(n,α){sup 7}Li the emerging charged particle leave their kinetic energy in the PADC forming a latent nuclear track, enlarged by chemical etching (6N, NaOH, 70°C). Track density provides information on the neutron density through calibration coefficient (∼1.6 10{sup 4} neutrons /track) obtained by a californium source. We report the estimation of the thermal and epithermal neutron field and its gradient for photoneutrons produced in radiotherapy treatments with 18 MV linear accelerators. It was obsered that photoneutron production have higher rate at the iso-center.

  12. Dose evaluation of boron neutron capture synovectomy using the THOR epithermal neutron beam: a feasibility study

    International Nuclear Information System (INIS)

    Rheumatoid arthritis is one of the most common epidemic diseases in the world. For some patients, the treatment with steroids or nonsteroidal anti-inflammatory drugs is not effective, thus necessitating physical removal of the inflamed synovium. Alternative approaches other than surgery will provide appropriate disease control and improve the patient's quality of life. In this research, we evaluated the feasibility of conducting boron neutron capture synovectomy (BNCS) with the Tsing Hua open-pool reactor (THOR) as a neutron source. Monte Carlo simulations were performed with arthritic joint models and uncertainties were within 5%. The collimator, reflector and boron concentration were optimized to reduce the treatment time and normal tissue doses. For the knee joint, polyethylene with 40%-enriched Li2CO3 was used as the collimator material, and a rear reflector of 15 cm thick graphite and side reflector of 10 cm thick graphite were chosen. The optimized treatment time was 5.4 min for the parallel-opposed irradiation. For the finger joint, polymethyl methacrylate was used as the reflector material. The treatment time can be reduced to 3.1 min, while skin and bone doses can be effectively reduced by approximately 9% compared with treatment using the graphite reflector. We conclude that using THOR as a treatment modality for BNCS could be a feasible alternative in clinical practice

  13. Determination of some elements by epithermal neutron activation analysis for the Arctic aerosol

    International Nuclear Information System (INIS)

    Nineteen trace elements in 685 aerosol filter samples collected during 1964-1978 in northern Finland by the Finnish Meteorological Institute have been determined. Some procedures and results are presented for very short (∼25 s), short (∼3-54 min), and medium (12-35 h) lived isotopes as determined by epithermal NAA in conjunction with and without Compton suppression. Elements with a Iγ/σth ratio are favorable to be determined by epithermal NAA. Silver was determined by a one minute epithermal irradiation because of a very short 110Ag half-life. Antimony, arsenic, cobalt, bromine, indium, iodine, potassium, silicon, tin, tungsten, and zinc were determined by a ten minute epithermal irradiation. For silver determination, samples were counted without transferring the filter from the irradiated vial, however, for ten minute irradiation all samples were transferred to a non-irradiated vial and counted both in the normal and Compton mode by the HPGe gamma-spectrometry system with a decay time of about 10 minutes and counting time of 15 minutes. Each day a maximum of 16 samples were irradiated and immediately following the short counting, these samples were loaded into an automatic sample changer in sequence of irradiation and counted for an hour in both normal and Compton modes. This has proven to be an extremely cost effective measure thus reducing the need to employ long-lived NAA to analyze other elements such as Ag, Co, Sn and Zn and Ag for air pollution source receptor modeling. (author)

  14. Epithermal neutrons activation analysis, radiochemical and radiometric investigations of evaporitic deposits of Slanic-Prahova (Romania) salt mine

    Energy Technology Data Exchange (ETDEWEB)

    Cristache, C.; Simion, C.A.; Margineanu, R.M. [National Inst. of Research and Development for Physics and Nuclear Engineering ' ' Horia - Hulubei' ' , Magurele (Ilfov) (Romania); Culicov, O.A.; Frontasyeva, M.V. [Joint Inst. of Nuclear Research, Dubna (Russian Federation); Matei, M. [National Society of Salt SALROM SA, Bucharest (Romania); Duliu, O.G. [Univ. of Bucharest, Dept. of Atomic and Nuclear Physics, Magurele (Ilfov) (Romania); National Inst. for Research and Development in Electrical Engineering, Bucharest (Romania)

    2009-07-01

    Three highly sensitive analytical methods: epithermal neutron activation analysis (ENAA), radiometric assay and UV/Vis spectroscopy were used to investigate the elemental composition of both halite and mineral fractions (sediments) of salt collected from the Slanic-Prahova salt mine, near the location of Low Background Radiation Lab. For halite with all three methods and within experimental uncertainties, it was not possible to observe the presence of any natural radioactive elements. For the mineral fraction both radiometric and ENAA showed the presence of {sup 40}K, {sup 232}Th and {sup 238}U in concentrations comparable to the upper continental core (UCC). The same was true for the distribution in the mineral fraction of 7 other major (Na, Al, Cl, K, Ca, Ti and Fe) and 29 trace elements (Sc, Cr, V, Mn, Ni, Co, Zn, Cu, As, Br, Rb, Sr, Zr, Mo, Sn, Sb, Cs, Ba, La, Ce, Ne, Eu, Sm, Tb, Hf, Ta, W, Th, U) as determined by epithermal neutron activation analysis (ENAA), which demonstrates a continental origin of the sediments in the existing salt deposit. (orig.)

  15. Epithermal neutrons activation analysis, radiochemical and radiometric investigations of evaporitic deposits of Slanic-Prahova (Romania) salt mine

    International Nuclear Information System (INIS)

    Three highly sensitive analytical methods: epithermal neutron activation analysis (ENAA), radiometric assay and UV/Vis spectroscopy were used to investigate the elemental composition of both halite and mineral fractions (sediments) of salt collected from the Slanic-Prahova salt mine, near the location of Low Background Radiation Lab. For halite with all three methods and within experimental uncertainties, it was not possible to observe the presence of any natural radioactive elements. For the mineral fraction both radiometric and ENAA showed the presence of 40K, 232Th and 238U in concentrations comparable to the upper continental core (UCC). The same was true for the distribution in the mineral fraction of 7 other major (Na, Al, Cl, K, Ca, Ti and Fe) and 29 trace elements (Sc, Cr, V, Mn, Ni, Co, Zn, Cu, As, Br, Rb, Sr, Zr, Mo, Sn, Sb, Cs, Ba, La, Ce, Ne, Eu, Sm, Tb, Hf, Ta, W, Th, U) as determined by epithermal neutron activation analysis (ENAA), which demonstrates a continental origin of the sediments in the existing salt deposit. (orig.)

  16. Characterization of the BMRR and PBF epithermal-neutron beams in phantom using three-dimensional deterministic radiation transport theory

    International Nuclear Information System (INIS)

    Calculation of physically-realistic radiation dose distribution for Boron Neutron Capture Therapy (BNCT) is a complex, three-dimensional problem. The Monte Carlo stochastic simulation technique has traditionally been the primary method for performing such calculations. A three-dimensional deterministic approach to the problem would offer some complementary advantages. Recently-completed work at the Idaho National Engineering Laboratory (INEL) has established that the three-dimensional discrete-ordinates (Sn) formulation offers such an approach. The method has been validated in detail against measurements taken in a canine-head Medical Research Reactor (BMRR) located at Brookhaven National Laboratory (BNL) in Upton, NY. In addition, three-dimensional deterministic calculations of all relevant BNCT dose components have been completed for the three-dimensional phantom in the proposed INEL Power Burst Facility (PBF) epithermal-neutron beam

  17. Thermal- and epithermal-neutron fluences estimated from redidual radioactivities in rocks exposed to Nagasaki atomic bomb

    International Nuclear Information System (INIS)

    Rocks 2 cm in depth were selected from the surface of rock, used as a river wall, within 1000 m from the hypocenter. Specific activities of Co-60 and Eu-152 present in the rocks were determined to calculate thermal neutron and epithermal neutron incident upon the rocks. Lower specific activities were associated with a longer distance from the hypocenter. Specific activities of Co-60 and Eu-152 at a straight distance of 503-511 m from the hypocenter were 63±13.0 Bq/mg and 7.39±1.06 Bq/mg, respectively. The corresponding figures at a straight distance of 590-630 m from the hypocenter were 26.9±8.5 Bq/mg and 4.73±0.49 Bq/mg. (N.K.)

  18. Installation of permanent cadmium-lined channel as a means for increasing epithermal NAA capabilities of miniature neutron source reactors

    International Nuclear Information System (INIS)

    Highlights: • High demand for epithermal neutrons necessitated the need of a permanent cadmium-line. • We reported the design specifications, preliminary studies done and steps followed. • Reactivity worth of the old channel = 0.12 mk and the new channel = 0.336 mk. • Temperature coefficient = −0.1 mk/°C and control rod worth coefficient = 0.023 mk/mm. • The work is a useful tool to the MNSR community for upgrading their reactors. -- Abstract: High demand for epithermal neutrons by the clients of the Nigerian Research Reactor-1 (NIRR-1), a Miniature Neutron Source Reactor (MNSR) has necessitated the need to explore avenues for increasing epithermal Neutron Activation Analysis (NAA) capabilities of the reactor. Safety and flux stability simulations were done by our group using Monte Carlo Transport Code MCNP5 for permanent cadmium line inside the irradiation channel of NIRR-1 and compared with the ones reported by other MNSR groups. The results of all these simulations revealed that the effect of cadmium-line on safety and flux stability is very minimal in the outer channel than in the inner channel. We have reported here the design specifications, preliminary studies done, steps followed in installation and measurements done in the pre and post installation of the permanent cadmium-line in outer channel of the reactor. We measured the reactivity worth of the old and new channel and readjusted the reactor's core excess reactivity after the installation. Results obtained are: reactivity worth of the old channel (0.12 mk), reactivity worth of the new channel = 0.336 mk, temperature coefficient = −0.1 mk/°C, control rod worth coefficient = 0.023 mk/mm and the core excess reactivity = 3.85 mk. We have also measured the radial and axial flux distribution in the channels of the reactor after the installation. The installation of the permanent cadmium-lined channel reported here will not only boost the sample handling capabilities of NIRR-1 but will also

  19. Study of the relative dose-response of BANG-3[reg] polymer gel dosimeters in epithermal neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Uusi-Simola, J [Department of Radiology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Savolainen, S [Department of Radiology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Kangasmaeki, A [Department of Radiology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Heikkinen, S [Department of Laboratory Diagnostics, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Perkioe, J [Department of Radiology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Ramadan, U Abo [Department of Laboratory Diagnostics, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Seppaelae, T [Department of Oncology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Karila, J [Department of Oncology, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Seren, T [VTT Processes, Technical Research Centre of Finland, FIN-02044 VTT, Finland (Finland); Kotiluoto, P [VTT Processes, Technical Research Centre of Finland, FIN-02044 VTT, Finland (Finland); Sorvari, P [Department of Laboratory Diagnostics, Helsinki University Central Hospital, FIN-00029 HUS (Finland); Auterinen, I [VTT Processes, Technical Research Centre of Finland, FIN-02044 VTT, Finland (Finland)

    2003-09-07

    Polymer gels have been reported as a new, potential tool for dosimetry in mixed neutron-gamma radiation fields. In this work, BANG-3 (MGS Research Inc.) gel vials from three production batches were irradiated with 6 MV photons of a Varian Clinac 2100 C linear accelerator and with the epithermal neutron beam of the Finnish boron neutron capture therapy (BNCT) facility at the FiR 1 nuclear reactor. The gel is tissue equivalent in main elemental composition and density and its T2 relaxation time is dependent on the absorbed dose. The T2 relaxation time map of the irradiated gel vials was measured with a 1.5 T magnetic resonance (MR) scanner using spin echo sequence. The absorbed doses of neutron irradiation were calculated using DORT computer code, and the accuracy of the calculational model was verified by measuring gamma ray dose rate with thermoluminescent dosimeters and {sup 55}Mn(n,{gamma}) activation reaction rate with activation detectors. The response of the BANG-3 gel dosimeter for total absorbed dose in the neutron irradiation was linear, and the magnitude of the response relative to the response in the photon irradiation was observed to vary between different gel batches. The results support the potential of polymer gels in BNCT dosimetry, especially for the verification of two- or three-dimensional dose distributions.

  20. Geochemistry of sediments and surface soils from the Nile Delta and lower Nile valley studied by epithermal neutron activation analysis

    Science.gov (United States)

    Arafa, Wafaa M.; Badawy, Wael M.; Fahmi, Naglaa M.; Ali, Khaled; Gad, Mohamed S.; Duliu, Octavian G.; Frontasyeva, Marina V.; Steinnes, Eiliv

    2015-07-01

    The distributions of 36 major and trace elements in 40 surface soil and sediment samples collected from the Egyptian section of the river Nile were determined by epithermal neutron activation analysis and compared with corresponding data for the Upper Continental Crust and North American Shale Composite. Their relative distributions indicate the presence of detrital material of igneous origin, most probably resulting from weathering on Ethiopian highlands and transported by the Blue Nile, the Nile main tributary. The distributions of the nickel, zinc, and arsenic contents suggest that the lower part of the Nile and its surroundings including the Nile Delta is not seriously polluted with metals from local human activity. The geographical distributions of Na, Cl, and I as well as results of principal component analysis suggest atmospheric supply of these elements from the ocean. In general the present data may contribute to a better understanding of the geochemistry of the Nile sediments.

  1. Epithermal neutron activation analysis of blue-green algae Spirulina platensis as a matrix for selenium-containing pharmaceuticals

    International Nuclear Information System (INIS)

    To evaluate the potentiality of the blue-green algae Spirulina platensis as a matrix for the production of Se-containing pharmaceuticals, the background levels of 31 major, minor and trace elements (Na, Mg, Al, Cl, K, Ca, Sc, V, Cr, Mn, Fe, Co, Ni using (n,p) reaction), As, Br, Zn, Rb, Mo, Ag, Sb, I, Ba, Sm, Tb, Tm, Hf, Ta, W, Au, Hg, Th were determined in Spirulina platensis biomass by means of epithermal neutron activation analysis. The possibility of the purpose-oriented incorporation of Se into Spirulina platensis biomass was demonstrated. The polynomial dependence of the Se accumulation on nutritional medium loading was revealed. The analytical technique used allows to control the amount of toxic elements in algae Spirulina platensis. Conclusion of the possibility to use Spirulina platensis as a matrix for the production of Se-containing pharmaceutical was drawn. (author)

  2. Determination of bromine, chlorine and iodine in environmental aqueous samples by epithermal neutron activation analysis and Compton suppression

    Science.gov (United States)

    Landsberger, S.; O'Kelly, D. J.; Braisted, J.; Panno, S.

    2006-01-01

    Halides, particularly Br- and Cl-, have been used as indicators of potential sources of Na+ and Cl- in surface water and groundwater with limited success. Contamination of groundwater and surface water by Na+ and Cl- is a common occurrence in growing urban areas and adversely affects municipal and private water supplies in Illinois and other states, as well as vegetation in environmentally sensitive areas. Neutron activation analysis (NAA) can be effectively used to determine these halogens, but often the elevated concentrations of sodium and chlorine in water samples can give rise to very high detection limits for bromine and iodine due to elevated backgrounds from the activation process. We present a detailed analytical scheme to determine Cl, Br and I in aqueous samples with widely varying Na and Cl concentrations using epithermal NAA in conjunction with Compton suppression. ?? 2006 Akade??miai Kiado??.

  3. Accelerator Based Neutron Beams for Neutron Capture Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yanch, Jacquelyn C.

    2003-04-11

    The DOE-funded accelerator BNCT program at the Massachusetts Institute of Technology has resulted in the only operating accelerator-based epithermal neutron beam facility capable of generating significant dose rates in the world. With five separate beamlines and two different epithermal neutron beam assemblies installed, we are currently capable of treating patients with rheumatoid arthritis in less than 15 minutes (knee joints) or 4 minutes (finger joints) or irradiating patients with shallow brain tumors to a healthy tissue dose of 12.6 Gy in 3.6 hours. The accelerator, designed by Newton scientific Incorporated, is located in dedicated laboratory space that MIT renovated specifically for this project. The Laboratory for Accelerator Beam Applications consists of an accelerator room, a control room, a shielded radiation vault, and additional laboratory space nearby. In addition to the design, construction and characterization of the tandem electrostatic accelerator, this program also resulted in other significant accomplishments. Assemblies for generating epithermal neutron beams were designed, constructed and experimentally evaluated using mixed-field dosimetry techniques. Strategies for target construction and target cooling were implemented and tested. We demonstrated that the method of submerged jet impingement using water as the coolant is capable of handling power densities of up to 6 x 10(sup 7) W/m(sup 2) with heat transfer coefficients of 10(sup 6)W/m(sup 2)-K. Experiments with the liquid metal gallium demonstrated its superiority compared with water with little effect on the neutronic properties of the epithermal beam. Monoenergetic proton beams generated using the accelerator were used to evaluate proton RBE as a function of LET and demonstrated a maximum RBE at approximately 30-40 keV/um, a finding consistent with results published by other researchers. We also developed an experimental approach to biological intercomparison of epithermal beams and

  4. Accelerator Based Neutron Beams for Neutron Capture Therapy

    International Nuclear Information System (INIS)

    The DOE-funded accelerator BNCT program at the Massachusetts Institute of Technology has resulted in the only operating accelerator-based epithermal neutron beam facility capable of generating significant dose rates in the world. With five separate beamlines and two different epithermal neutron beam assemblies installed, we are currently capable of treating patients with rheumatoid arthritis in less than 15 minutes (knee joints) or 4 minutes (finger joints) or irradiating patients with shallow brain tumors to a healthy tissue dose of 12.6 Gy in 3.6 hours. The accelerator, designed by Newton scientific Incorporated, is located in dedicated laboratory space that MIT renovated specifically for this project. The Laboratory for Accelerator Beam Applications consists of an accelerator room, a control room, a shielded radiation vault, and additional laboratory space nearby. In addition to the design, construction and characterization of the tandem electrostatic accelerator, this program also resulted in other significant accomplishments. Assemblies for generating epithermal neutron beams were designed, constructed and experimentally evaluated using mixed-field dosimetry techniques. Strategies for target construction and target cooling were implemented and tested. We demonstrated that the method of submerged jet impingement using water as the coolant is capable of handling power densities of up to 6 x 10(sup 7) W/m(sup 2) with heat transfer coefficients of 10(sup 6)W/m(sup 2)-K. Experiments with the liquid metal gallium demonstrated its superiority compared with water with little effect on the neutronic properties of the epithermal beam. Monoenergetic proton beams generated using the accelerator were used to evaluate proton RBE as a function of LET and demonstrated a maximum RBE at approximately 30-40 keV/um, a finding consistent with results published by other researchers. We also developed an experimental approach to biological intercomparison of epithermal beams and

  5. Probing Planetary Bodies for Subsurface Volatiles: GEANT4 Models of Gamma Ray, Fast, Epithermal, and Thermal Neutron Response to Active Neutron Illumination

    Science.gov (United States)

    Chin, G.; Sagdeev, R.; Su, J. J.; Murray, J.

    2014-12-01

    Using an active source of neutrons as an in situ probe of a planetary body has proven to be a powerful tool to extract information about the presence, abundance, and location of subsurface volatiles without the need for drilling. The Dynamic Albedo of Neutrons (DAN) instrument on Curiosity is an example of such an instrument and is designed to detect the location and abundance of hydrogen within the top 50 cm of the Martian surface. DAN works by sending a pulse of neutrons towards the ground beneath the rover and detecting the reflected neutrons. The intensity and time of arrival of the reflection depends on the proportion of water, while the time the pulse takes to reach the detector is a function of the depth at which the water is located. Similar instruments can also be effective probes at the polar-regions of the Moon or on asteroids as a way of detecting sequestered volatiles. We present the results of GEANT4 particle simulation models of gamma ray, fast, epithermal, and thermal neutron responses to active neutron illumination. The results are parameterized by hydrogen abundance, stratification and depth of volatile layers, versus the distribution of neutron and gamma ray energy reflections. Models will be presented to approximate Martian, lunar, and asteroid environments and would be useful tools to assess utility for future NASA exploration missions to these types of planetary bodies.

  6. Examination of Greek neolithic ceramic shards by epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    At the reactor of the NCSR 'Demokritos' epithermal irradiation was used in connection with a loss-free counting technique to investigate rare Neolithic ceramic shards, about 4000 years old, from the Alepotrypa Cave of Diros, Greece. The application of an irradiation time of 30 minutes, the measurements of the samples after less then 24 hours and a counting time of 20 minutes in connection with a loss-free counting unit allowed the determination of 12 elements per sample. The comparison of these rare fine ceramic shards with those of primitive shape showed that both were produced from the same raw materials. Small differences could be explained by a raw material pretreatment. The Neolithic potters were obviously aware of separation techniques in order to obtain fine clay fractions to produce those rare ceramics. (author)

  7. Monte Carlo Calculation Of Thermal And Epithermal Neutron Self-Shielding Factors

    International Nuclear Information System (INIS)

    Neutron activation measurement is often performed in a reactor neutron spectrum. When the size of the irradiation sample is not small enough and resonance peaks present in the cross section of the sample nuclide, the thermal and resonance self-shielding effects of neutron flux in the sample must be considered for correction. In this work, the Monte Carlo code MCNP-5 has been applied for calculation of the self-shielding factors for several standard samples and neutron monitors that are often used in measurements of thermal neutron capture cross sections and resonance integrals. The results of calculation are tabulated with different sample thickness and different irradiation geometries. (author)

  8. Reactor AQUILON. The hardening of neutron spectrum in natural uranium rods, with a computation of epithermal fissions (1961); Pile AQUILON. Durcissement du spectre des neutrons dans les barreaux d'uranium et calcul des fissions epithermiques (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Durand -Smet, R.; Lourme, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    - Microscopic flux measurements in reactor Aquilon have allowed to investigate the thermal and epithermal flux distribution in natural uranium rods, then to obtain the neutron spectrum variations in uranium, Wescott '{beta}' term of the average spectrum in the rod, and the ratio of epithermal to therma fissions. A new definition for the infinite multiplication factor is proposed in annex, which takes into account epithermal parameters. (authors) [French] - Un certain nombre de mesures effectuees dans la pile Aquilon ont permis d'etablir la distribution fine des flux thermique et epithermique dans les barreaux d'uranium, et d'en deduire les variations du spectre des neutrons dans l'uranium, le terme {beta} du spectre de Wescott moyen dans le barreau et le nombre de fissions epithermiques. En annexe, il est propose une definition nouvelle du coefficient de multiplication infini, qui fait intervenir les parametres epithermiques. (auteurs)

  9. Isotope identification capabilities using time resolved prompt gamma emission from epithermal neutrons

    International Nuclear Information System (INIS)

    We present a concept of integrated measurements for isotope identification which takes advantage of the time structure of spallation neutron sources for time resolved γ spectroscopy. Time resolved Prompt Gamma Activation Analysis (T-PGAA) consists in the measurement of gamma energy spectrum induced by the radioactive capture as a function of incident neutron Time Of Flight (TOF), directly related with the energy of incident neutrons. The potential of the proposed concept was explored on INES (Italian Neutron Experimental Station) at the ISIS spallation neutron source (U.K.). Through this new technique we show an increase in the sensitivity to specific elements of archaeometric relevance, through incident neutron energy selection in prompt γ spectra for multicomponent samples. Results on a standard bronze sample are presented

  10. Epithermal neutron activation, radiometric, correlation and principal component analysis applied to the distribution of major and trace elements in some igneous and metamorphic rocks from Romania

    Energy Technology Data Exchange (ETDEWEB)

    Cristache, C.I. [National Institute of Research and Development for Physics and Nuclear Engineering Horia-Hulubei, P.O. Box MG-6, 077125 Magurele, Ilfov (Romania); Duliu, O.G. [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele, Ilfov (Romania)], E-mail: duliu@b.astral.ro; Culicov, O.A.; Frontasyeva, M.V. [Joint Institute of Nuclear Research, 6, Joliot Curie str. 141980, Dubna (Russian Federation); Ricman, C. [Geological Institute of Romania, 1 Caransebes Street, 012271 Bucharest (Romania); Toma, M. [National Institute of Research and Development for Physics and Nuclear Engineering Horia-Hulubei, P.O. Box MG-6, 077125 Magurele, Ilfov (Romania)

    2009-05-15

    Six major (Na, Al, K, Ca, Ti, Fe) and 28 trace (Sc, Cr, V, Mn, Co, Zn, Cu, As, Br, Sr, Rb, Zr, Mo, Sn, Sb, Ba, Cs, La, Ce, Nd, Eu, Sm, Tb, Hf, Ta, W, Th and U) elements were determined by epithermal neutron activation analysis (ENAA) in nine Meridional Carpathian and Macin Mountains samples of igneous and metamorphic rocks. Correlation and principal factor analysis were used to interpret data while natural radionuclides radiometry shows a good correlation with ENAA results.

  11. Study of suitability of Fricke-gel-layer dosimeters for in-air measurements to characterise epithermal/thermal neutron beams for NCT.

    Science.gov (United States)

    Gambarini, G; Artuso, E; Giove, D; Felisi, M; Volpe, L; Barcaglioni, L; Agosteo, S; Garlati, L; Pola, A; Klupak, V; Viererbl, L; Vins, M; Marek, M

    2015-12-01

    The reliability of Fricke gel dosimeters in form of layers for measurements aimed at the characterization of epithermal neutron beams has been studied. By means of dosimeters of different isotopic composition (standard, containing (10)B or prepared with heavy water) placed against the collimator exit, the spatial distribution of gamma and fast neutron doses and of thermal neutron fluence are attained. In order to investigate the accuracy of the results obtained with in-air measurements, suitable MC simulations have been developed and experimental measurements have been performed utilizing Fricke gel dosimeters, thermoluminescence detectors and activation foils. The studies were related to the epithermal beam designed for BNCT irradiations at the research reactor LVR-15 (Řež). The results of calculation and measurements have revealed good consistency of gamma dose and fast neutron 2D distributions obtained with gel dosimeters in form of layers. In contrast, noticeable modification of thermal neutron fluence is caused by the neutron moderation produced by the dosimeter material. Fricke gel dosimeters in thin cylinders, with diameter not greater than 3mm, have proved to give good results for thermal neutron profiling. For greater accuracy of all results, a better knowledge of the dependence of gel dosimeter sensitivity on radiation LET is needed. PMID:26249744

  12. Physical parameters and biological effects of the LVR-15 epithermal neutron beam

    Czech Academy of Sciences Publication Activity Database

    Burian, J.; Gambarini, G.; Marek, M.; Mareš, Vladislav; Rejchrt, J.; Vanossi, E.; Viererbl, L.; Judas, L.

    -, - (2006), s. 481-484. [International Congress on Neutron Capture Therapy /12./. Kagawo, 09.10.2006-13.10.2006] R&D Projects: GA MPO(CZ) 1H-PK2/05 Institutional research plan: CEZ:AV0Z50110509 Keywords : brain tumors * neutron capture therapy * NTC * dosimetry Subject RIV: FD - Oncology ; Hematology

  13. Performance evaluation of the source description of the THOR BNCT epithermal neutron beam

    International Nuclear Information System (INIS)

    This paper aims to evaluate the performance of the source description of the THOR BNCT beam via different measurement techniques in different phantoms. The measurement included (1) the absolute reaction rate measurement of a set of triple activation foils, (2) the neutron and gamma-ray dose rates measured using the paired ionization chamber method, and (3) the relative reaction rate distributions obtained using the indirect neutron radiography. Three source descriptions, THOR-Y09, surface source file RSSA, and THOR-50C, were tested. The comparison results concluded that THOR-Y09 is a well-tested source description not only for neutron components, but also for gamma-ray component.

  14. Estimation of total and bioaccessible levels of iodine in edible seaweeds of Japan by epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    Edible seaweeds play important roles as daily source of minerals and dietary fibers for Japanese population groups. It is therefore of interest to estimate the intake of minerals and dietary fibers from seaweeds. Although the levels of iodine can be measured by ICP-MS in liquid samples such as urine and water, it is rather difficult to do the same in seaweeds due to polysaccharides in them. In this study, the following eight edible seaweeds were collected from local shores or purchased from stores. Sea mustard is the most popular edible seaweed in Japan; it starts growing quickly in January until it reaches a height of about 2 m in March. Sea mustards in different growing stages were collected, cut into several longitudinal pieces, freeze dried, and pulverized. Dietary fiber was separated from dried powder by in vitro enzymolysis using α-Amylase, protease, and amyloglucosidase. Portions of dried powder and dietary fiber were irradiated for 1-5 min at the Dalhousie University SLOWPOKE-2 Reactor (DUSR) in Canada or the Kyoto University Reactor (KUR) in Japan. After appropriate cooling time, the 442.9-keV gamma-ray of 128I was used to assay iodine by epithermal instrumental neutron activation analysis (EINAA). Total and bioaccesible iodine levels in eight edible seaweeds are shown

  15. Epithermal instrumental neutron activation analysis with Compton suppression spectrometry for the determination of iodine in food samples

    International Nuclear Information System (INIS)

    Epithermal instrumental neutron activation analysis (EINAA) together with Compton suppression system were optimized and used to analyze several food samples for the determination of low levels of iodine. The method involved the irradiation of samples in the outer epi-cadmium site of the Dalhousie University Slowpoke-2 reactor facility. The samples were then counted directly without any chemical treatment on an anticoincidence counting system. This system comprised a 25 cm3 hyperpure Ge detector, a guard detector consisting of a 10'' x 10'' NaI(Tl) annulus with five photomultiplier tubes (PMTs) and a 3' x 3' NaI(Tl) plug with one PMT. Iodine was quantitatively analyzed using the 443 keV photopeak of 128I. The precision and accuracy of the method were evaluated using real samples and biological reference materials, respectively. The precision of the method was calculated as percent relative standard deviation and in all cases was within ±5%. The agreement between our iodine values and those of the certified values was generally within ±10%, suggesting an excellent accuracy of the method. The detection limits of the various samples calculated, with the lowest value of 20 ppb. The values of iodine determined ranged between 24 to 3080 ppb. The methods and results are presented. (author)

  16. Thermal or epithermal reactor

    International Nuclear Information System (INIS)

    In a thermal or epithermal heavy-water reactor of the pressure tube design the reactivity is to be increased by different means: replacement of the moderator by additional rods with heavy metal in the core or in the reflector; separation of the moderator (heavy water) from the coolant (light water) by means of shroud tubes. In light-water reactor types neutron losses are to be influenced by using the heavy elements in different configurations. (orig./PW)

  17. Reprint of The improvement of the energy resolution in epi-thermal neutron region of Bonner sphere using boric acid water solution moderator.

    Science.gov (United States)

    Ueda, H; Tanaka, H; Sakurai, Y

    2015-12-01

    Bonner sphere is useful to evaluate the neutron spectrum in detail. We are improving the energy resolution in epi-thermal neutron region of Bonner sphere, using boric acid water solution as a moderator. Its response function peak is narrower than that for polyethylene moderator and the improvement of the resolution is expected. The resolutions between polyethylene moderator and boric acid water solution moderator were compared by simulation calculation. Also the influence in the uncertainty of Bonner sphere configuration to spectrum estimation was simulated. PMID:26508275

  18. The improvement of the energy resolution in epi-thermal neutron region of Bonner sphere using boric acid water solution moderator.

    Science.gov (United States)

    Ueda, H; Tanaka, H; Sakurai, Y

    2015-10-01

    Bonner sphere is useful to evaluate the neutron spectrum in detail. We are improving the energy resolution in epi-thermal neutron region of Bonner sphere, using boric acid water solution as a moderator. Its response function peak is narrower than that for polyethylene moderator and the improvement of the resolution is expected. The resolutions between polyethylene moderator and boric acid water solution moderator were compared by simulation calculation. Also the influence in the uncertainty of Bonner sphere configuration to spectrum estimation was simulated. PMID:26133664

  19. MANTRA: An Integral Reactor Physics Experiment to Infer the Neutron Capture Cross Sections of Actinides and Fission Products in Fast and Epithermal Spectra

    Science.gov (United States)

    Youinou, G.; Vondrasek, R.; Veselka, H.; Salvatores, M.; Paul, M.; Pardo, R.; Palmiotti, G.; Palchan, T.; Nusair, O.; Nimmagadda, J.; Nair, C.; Murray, P.; Maddock, T.; Kondrashev, S.; Kondev, F. G.; Jones, W.; Imel, G.; Glass, C.; Fonnesbeck, J.; Berg, J.; Bauder, W.

    2014-05-01

    This paper presents an update of an on-going collaborative INL-ANL-ISU integral reactor physics experiment whose objective is to infer the effective neutron capture cross sections for most of the actinides of importance for reactor physics and fuel cycle studies in both fast and epithermal spectra. Some fission products are also being considered. The principle of the experiment is to irradiate very pure actinide samples in the Advanced Test Reactor at INL and, after a given time, determine the amount of the different transmutation products. The determination of the nuclide densities before and after neutron irradiation together with the neutron fluence will allow inference of effective neutron capture cross-sections in different neutron spectra.

  20. Usage of a single TLD-700 for gamma dose measurement in a water phantom irradiated with the epithermal neutron beam at the thor research reactor

    International Nuclear Information System (INIS)

    There are two groups of data that need to be compared in the water phantom irradiated with an epithermal neutron beam for BNCT: (1) the thermal neutron flux, and (2) the gamma dose rate. The comparisons of gamma dose rates between MCNP calculation and TLD measurement are more complex than thermal neutron flux comparison, because of the gamma dose rate can not be taken from TLD-700 readings directly. TLD-700 dose rates contain gamma dose rate, neutron dose rate, and neutron-6Li reaction dose rate. In this article, the responses of TLD-700 to different radiation components were investigated. The results were used for modification to the TLD-700 readings. By this way, the gamma dose rates show a good agreement between the simulation results and experimental data. (author)

  1. Application of epithermal neutron activation in multielement analysis of silicate rocks employing both coaxial Ge(Li) and low energy photon detector systems

    Science.gov (United States)

    Baedecker, P.A.; Rowe, J.J.; Steinnes, E.

    1977-01-01

    The instrumental activation analysis of silicate rocks using epithermal neutrons has been studied using both high resolution coaxial Ge(Li) detectors and low energy photon detectors, and applied to the determination of 23 elements in eight new U.S.G.S. standard rocks. The analytical use X-ray peaks associated with electron capture or internal conversion processes has been evaluated. Of 28 elements which can be considered to be determinable by instrumental means, the epithermal activation approach is capable of giving improved sensitivity and precision in 16 cases, over the normal INAA procedure. In eleven cases the use of the low energy photon detector is thought to show advantages over convertional coaxial Ge(Li) spectroscopy. ?? 1977 Akade??miai Kiado??.

  2. The background cross section method for calculating the epithermal neutron spectra

    International Nuclear Information System (INIS)

    We have developed a new methodology to the multigroup constants calculations, for thermal and fast reactors. The method to obtain the constants is extremely fast and simple, and it avoid repeated computations of the detailed neutron spectrum for different cell configurations (composition, geometry and temperature). (author)

  3. Epithermal paleosurfaces

    Science.gov (United States)

    Sillitoe, Richard H.

    2015-10-01

    Many active volcanic-hydrothermal and geothermal systems are characterized by distinctive surface and near-surface landforms and products, which are generated during discharge of a spectrum of fluid types under varied conditions. Remnants of most of these products are preserved in some of their less-eroded, extinct equivalents: epithermal deposits of high-sulfidation (HS), intermediate-sulfidation (IS), and low-sulfidation (LS) types. Steam-heated alteration occupying vadose zones and any underlying silicified horizons formed at paleogroundwater tables characterize HS, IS, and LS deposits as do hydrothermal eruption craters and their subaerial or shallow sub-lacustrine breccia aprons and laminated infill. Although rarely recognized, HS, IS, and LS systems can also contain finely laminated, amorphous silica sediments that accumulated in acidic lakes and mud pots and, exclusive to HS systems, in hyperacidic crater lakes. In contrast, silica sinter and more distal carbonate travertine are hot spring discharge products confined mainly to LS and IS settings, as both form from near-neutral-pH liquids. Hydrothermal chert deposition and sediment silicification can take place in shallow, lacustrine rift settings, also largely restricted to LS and IS deposits. These surface and near-surface hydrothermal products are typically metal deficient, although mercury concentrations are relatively commonplace and were formerly exploited in places. Nonetheless, sinters, hydrothermal eruption craters, and silicified lacustrine sediments may contain anomalously high precious metal values; indeed, the last of these locally constitutes low-grade, bulk-tonnage orebodies. The dynamic nature of epithermal paleosurfaces, caused by either syn-hydrothermal aggradation or degradation, can profoundly affect deposit evolution, leading to either eventual burial or telescoping of shallower over deeper alteration ± precious metal mineralization. Formational age, tectonic and climatic regime

  4. The Effect of Non-Uniform Moderator Temperature on the Epithermal Neutron Spectrum

    International Nuclear Information System (INIS)

    The neutron spectrum from a high energy source in an infinite 1/v absorbing medium, possessing a non-uniform temperature variation, is obtained for an arbitrary scattering kernel. The diffusion approximation has been employed to represent the spatial variation of flux, and methods are discussed whereby the full Boltzmann equation can also be used. The resulting energy spectrum is in the form of an asymptotic series in inverse powers of neutron velocity. The first and second terms in the series are spatially constant and represent the well known 1/E slowing-down flux with a correction for absorption. Succeeding terms depend upon the spatial variation of the physical temperature and contain quantities which are functions of the chemical binding and absorption of the moderator. For constant temperature, the solution becomes identical to that derived some years ago by Corngold for infinite homogeneous media. Numerical results are presented for various moderators and physical temperature variations. (author)

  5. Determination of elemental concentrations in airborne particulate matter in the City of Santiago de Chile, through neutron activation analysis using epithermal neutrons and Compton suppression system

    International Nuclear Information System (INIS)

    In order to optimize the Neutron-Activation Analysis (NAA) technique currently carried out in our country, the present work was carried out in the United States where irradiations with epithermal neutrons and a Compton suppression system were used, which allowed the characterization of aerosols of the city of Santiago de Chile. With this purpose, 54 filters of polycarbonate membranes were analysed with aerosols collected in an area of the capital during Spring 1993 and Winter of 1994. As a result, an improvement in the detection limits was observed, specially in elements such as Ni and Zn, which are not easily detectable through NAA. The application of both systems also permits the usage of this technique in geological and biological samples, where the presence of Na, Al and Cl obstruct the determination of some elements. The determined elements in both fractions were Mn, V, Cu, As, Sb, Co, Br, Cl, Ni, Zn, Ca, Al, Na and Fe. (author). 8 refs., 7 figs., 9 tabs

  6. Boron neutron capture therapy (BNCT) for glioblastoma multiforme (GBM), using the epithermal neutron beam at the Brookhaven National Laboratory

    International Nuclear Information System (INIS)

    Objective: BNCT is a binary treatment modality based on the nuclear reactions that occur when boron (10B) is exposed to thermal neutrons. Preclinical studies have demonstrated the therapeutic efficacy of p-boronophenylalanine (BPA)-based BNCT. The objective of the Phase I/II trial was to evaluate BPA-fructose (BPA-F) as a boron delivery agent for GBM and to study the feasibility and safety of a single-fraction of BNCT. Materials and Methods: The trial design required i) a BPA-F biodistribution study performed at the time of craniotomy; and ii) BNCT within 4 weeks of the craniotomy. From September 94 to July 95, 10 patients with biopsy proven GBM were treated. All but 1 patient underwent a biodistribution study receiving IV BPA-F at the time of craniotomy. Multiple tissue samples and concurrent blood and urine samples were collected for evaluation of the boron concentration and clearance kinetics. For BNCT all patients received 250 mg/kgm of BPA-F (IV infusion over 2 hrs) followed by neutron irradiation. The blood 10B concentration during irradiation was used to calculate the time of neutron exposure. The 3D treatment planning was done using the BNCT treatment planning software developed at the Idaho National Engineering Laboratory. The BNCT dose is expressed as the sum of the physical dose components corrected for both the RBE and the 10B localization factor with the unit Gy-Eq. The photon-equivalent dose, where the thermal neutron fluence reaches a maximum, is the peak-dose equivalent. A single-fraction of BNCT was delivered prescribing 10.5 Gy-Eq (9 patients) and 13.8 Gy-Eq (1 patient) as the peak dose-equivalent to the normal brain. The peak dose rate was kept below 27 cGy-Eq/min. Results: Biodistribution data: The maximum blood 10B concentration was observed at the end of the infusion and scaled as a linear function of the administered dose. The 10B concentration in the scalp and in the GBM tissue was higher than in blood by 1.5 x and at least 3.5 x

  7. Spectrum shaping of accelerator-based neutron beams for BNCT

    CERN Document Server

    Montagnini, B; Esposito, J; Giusti, V; Mattioda, F; Varone, R

    2002-01-01

    We describe Monte Carlo simulations of three facilities for the production of epithermal neutrons for Boron Neutron Capture Therapy (BNCT) and examine general aspects and problems of designing the spectrum-shaping assemblies to be used with these neutron sources. The first facility is based on an accelerator-driven low-power subcritical reactor, operating as a neutron amplifier. The other two facilities have no amplifier and rely entirely on their primary sources, a D-T fusion reaction device and a conventional 2.5 MeV proton accelerator with a Li target, respectively.

  8. Epithermal neutron activation, radiometric, correlation and principal component analysis applied to the distribution of major and trace elements in some igneous and metamorphic rocks from Romania.

    Science.gov (United States)

    Cristache, C I; Duliu, O G; Culicov, O A; Frontasyeva, M V; Ricman, C; Toma, M

    2009-05-01

    Six major (Na, Al, K, Ca, Ti, Fe) and 28 trace (Sc, Cr, V, Mn, Co, Zn, Cu, As, Br, Sr, Rb, Zr, Mo, Sn, Sb, Ba, Cs, La, Ce, Nd, Eu, Sm, Tb, Hf, Ta, W, Th and U) elements were determined by epithermal neutron activation analysis (ENAA) in nine Meridional Carpathian and Macin Mountains samples of igneous and metamorphic rocks. Correlation and principal factor analysis were used to interpret data while natural radionuclides radiometry shows a good correlation with ENAA results. PMID:19231213

  9. The improvement of the energy resolution in epi-thermal neutron region of Bonner sphere using boric acid water solution moderator

    International Nuclear Information System (INIS)

    Bonner sphere is useful to evaluate the neutron spectrum in detail. We are improving the energy resolution in epi-thermal neutron region of Bonner sphere, using boric acid water solution as a moderator. Its response function peak is narrower than that for polyethylene moderator and the improvement of the resolution is expected. The resolutions between polyethylene moderator and boric acid water solution moderator were compared by simulation calculation. Also the influence in the uncertainty of Bonner sphere configuration to spectrum estimation was simulated. - Highlights: • Boric acid solution is useful to improve the energy resolution of Bonner sphere. • Uncertainty of the device configuration is critical for neutron spectrometry. • It is important to reduce and evaluate the uncertainty

  10. Epithermal interrogation of fissile waste

    Energy Technology Data Exchange (ETDEWEB)

    Coop, K.L.; Hollas, C.L.

    1996-09-01

    Self-shielding of interrogating thermal neutrons in lumps of fissile material can be a major source of error in transuranic waste assay using the widely employed differential dieaway technique. We are developing a new instrument, the combined thermal/epithermal neutron (CTEN) interrogation instrument to detect the occurrence of self- shielding and mitigate its effects. Neutrons are moderated in the graphite walls of the CTEN instrument to provide an interrogating flux of epithermal and thermal neutrons. The induced prompt fission neutrons are detected in proportional counters. We report the results of measurements made with the CTEN instrument, using minimal and highly self-shielding plutonium and uranium sources in 55 gallon drums containing a variety of mock waste matrices. Fissile isotopes and waste forms for which the method is most applicable, and limitations associated with the hydrogen content of the waste package/matrix are described.

  11. Epithermal interrogation of fissile waste

    International Nuclear Information System (INIS)

    Self-shielding of interrogating thermal neutrons in lumps of fissile material can be a major source of error in transuranic waste assay using the widely employed differential dieaway technique. We are developing a new instrument, the combined thermal/epithermal neutron (CTEN) interrogation instrument to detect the occurrence of self- shielding and mitigate its effects. Neutrons are moderated in the graphite walls of the CTEN instrument to provide an interrogating flux of epithermal and thermal neutrons. The induced prompt fission neutrons are detected in proportional counters. We report the results of measurements made with the CTEN instrument, using minimal and highly self-shielding plutonium and uranium sources in 55 gallon drums containing a variety of mock waste matrices. Fissile isotopes and waste forms for which the method is most applicable, and limitations associated with the hydrogen content of the waste package/matrix are described

  12. GEOLOGY, GEOCHEMISTRY AND FLUID INCLUSION STUDY OF THE BATURAPPE EPITHERMAL SILVER-BASE METAL PROSPECT, SOUTH SULAWESI, INDONESIA

    OpenAIRE

    Nur, Irzal

    2012-01-01

    The Baturappe epithermal silver-base metal prospect is situated in south of Sulawesi island, Indonesia. The prospect lies in the shoshonitic/alkaline southern arm of the Tertiary western Sulawesi plutono-volcanic arc. The Baturappe prospect is developed in the late Middle-Miocene Baturappe Volcanics which in the study area consists of respectively from the older to the younger: basaltic-andesitic lava, gabbroic-dioritic stock, and basaltic-andesitic dykes. Mineralizat...

  13. Boron neutron capture therapy of glioblastoma multiforme using the p- boronophenylalanine-fructose complex and epithermal neutrons

    International Nuclear Information System (INIS)

    The amino acid analogue p-boronophenylalanine (BPA) is under investigation as a neutron capture agent for BNCT of glioblastoma multiforme. A series of patients undergoing surgical removal of tumor received BPA orally as the free amino acid. Favorable tumor/blood boron concentration ratios were obtained but the absolute amount of boron in the tumor would have been insufficient for BNCT. BPA can be solubilized at neutral pH by complexation with fructose (BPA-F). Studies with rats suggest that intraperitoneal injection of BPA-F complex produces a much higher tumor boron concentration to rat intracerebral 9L gliosarcoma that were possible with oral BPA. Higher boron concentrations have allowed higher tumor radiation doses to be delivered while maintaining the dose to the normal brain vascular endothelium below the threshold of tolerance. The experience to date of the administration of BPA-F to one patient is provided in this report

  14. Boron neutron capture therapy of glioblastoma multiforme using the p- boronophenylalanine-fructose complex and epithermal neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Coderre, J.A.; Chanana, A.D.; Joel, D.D.; Liu, H.B.; Slatkin, D.N.; Wielopolski, L. [Brookhaven National Lab., Upton, NY (United States); Bergland, R.; Elowitz, E. [Beth Israel Medical Center, New York, NY (United States). Dept. of Neurosurgery; Chadha, M. [Beth Israel Medical Center, New York, NY (United States). Dept. of Radiation Oncology

    1994-12-31

    The amino acid analogue p-boronophenylalanine (BPA) is under investigation as a neutron capture agent for BNCT of glioblastoma multiforme. A series of patients undergoing surgical removal of tumor received BPA orally as the free amino acid. Favorable tumor/blood boron concentration ratios were obtained but the absolute amount of boron in the tumor would have been insufficient for BNCT. BPA can be solubilized at neutral pH by complexation with fructose (BPA-F). Studies with rats suggest that intraperitoneal injection of BPA-F complex produces a much higher tumor boron concentration to rat intracerebral 9L gliosarcoma that were possible with oral BPA. Higher boron concentrations have allowed higher tumor radiation doses to be delivered while maintaining the dose to the normal brain vascular endothelium below the threshold of tolerance. The experience to date of the administration of BPA-F to one patient is provided in this report.

  15. Neutron elastic scattering cross-sections measurement on carbon and fluorine in epithermal energy range using PEREN platform

    International Nuclear Information System (INIS)

    Molten Salt Reactor (MSR) based on Th/U cycle is one of the new generation concepts for nuclear energy production. A typical MSR is a graphite-moderated core with liquid fuel (7LiF +ThF4 + UF4). Many numerical studies based on Monte-Carlo codes are currently carried out but the validity of these numerical result relies on the precise knowledge of neutron cross sections used such as elastic scattering on carbon (σC), fluorine (σF) and lithium 7 (σLi). The goal of this work is to obtain σC and σF between 1 eV and 100 keV. Such measurements have been performed at the Laboratoire de Physique Subatomique et de Cosmologie (LPSC) de Grenoble on the experimental platform PEREN using slowing-down time spectrometers (C and CF2) associated to a pulsed neutron generator (GENEPI). Capture rates are obtained for reference materials (Au, Ag, Mo and In) using YAP scintillator coupled to a photo-multiplier. Very precise simulations (MCNP code) of the experimental setup have been performed and comparison with experiments has led to the determination of σC and σF with accuracies of 1% and 2% respectively. These results show a small discrepancy to evaluated nuclear data file (ENDF). Measures of total cross-sections σC and σF at higher energy (200 - 600 keV) were also carried out at Centre des Etudes Nucleaires de Bordeaux using a transmission method. Mono-energetic neutrons were produced by protons accelerated by a Van de Graaff accelerator on a LiF target and transmitted neutrons are counted in a proportional hydrogen gaseous detector. Discrepancies of 5% and 9% for σC and σF respectively with ENDF have been shown. (author)

  16. Accelerator based neutron source for the neutron capture therapy at hospital

    International Nuclear Information System (INIS)

    Accelerator source of epithermal neutrons for the hospital-based boron neutron capture therapy is proposed and discussed. Kinematically collimated neutrons are produced via near-threshold 7Li(p, n)7Be reaction at proton energies of 1.883 - 1.9 MeV. Steady-state accelerator current of 40 mA allows to provide therapeutically useful beams with treatment times of tens of minutes. The basic components of the facility are a hydrogen negative ion source, an electrostatic tandem accelerator with vacuum insulation, a sectioned rectifier, and a thin lithium neutron generating target on the surface of tungsten disk cooled by liquid metal heat carrier. Design features of facility components are discussed. The possibility of stabilization of proton energy is considered. At proton energy of 2.5 MeV the neutron beam production for NCT usage after moderation is also considered. (author)

  17. Evaluation of thermal neutron irradiation field using a cyclotron-based neutron source for alpha autoradiography

    International Nuclear Information System (INIS)

    It is important to measure the microdistribution of 10B in a cell to predict the cell-killing effect of new boron compounds in the field of boron neutron capture therapy. Alpha autoradiography has generally been used to detect the microdistribution of 10B in a cell. Although it has been performed using a reactor-based neutron source, the realization of an accelerator-based thermal neutron irradiation field is anticipated because of its easy installation at any location and stable operation. Therefore, we propose a method using a cyclotron-based epithermal neutron source in combination with a water phantom to produce a thermal neutron irradiation field for alpha autoradiography. This system can supply a uniform thermal neutron field with an intensity of 1.7×109 (cm−2 s−1) and an area of 40 mm in diameter. In this paper, we give an overview of our proposed system and describe a demonstration test using a mouse liver sample injected with 500 mg/kg of boronophenyl-alanine. - Highlights: • We developed a thermal neutron irradiation field using cyclotron based epithermal neutron source combination with a water phantom for alpha autoradiography. • The uniform thermal neutron irradiation field with an intensity of 1.7×109 (cm−2 s−1) with a size of 40 mm in diameter was obtained. • Demonstration test of alpha autoradiography using a liver sample with the injection of BPA was performed. • Boron image discriminated with the background event of protons was clearly shown by means of the particle identification

  18. Measurement of thermal neutron fluence rate of in-hospital neutron irradiator by SSNTD

    International Nuclear Information System (INIS)

    In-hospital neutron irradiator (IHNI) is an especially designed nuclear device based on Miniature Neutron Source Reactor (MNSR) for boron neutron capture therapy (BNCT). Its rated power is 30 kW. There are a thermal neutron beam and an epithermal neutron beam for treating patients at the opposite of the core. From the thermal neutron beam, a test beam is fetched out for measurement of boron concentration in blood by prompt γ neutron activation analysis (PGNAA) method. The neutron fluence rates at the end of thermal, epithermal and test neutron beam were measured by 235U fissile target and mica slice detector. At rated power, they are 1.67 × 109, 2.44 × 107 and 3.03 × 106 cm-2 · s-1, respectively. The results show that the thermal and epithermal neutron fluence rate can meet the requirement of BNCT and test neutron fluence rate meets the requirement of PGNAA. (authors)

  19. Experimental characterization of semiconductor-based thermal neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bedogni, R., E-mail: roberto.bedogni@lnf.infn.it [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); Bortot, D.; Pola, A.; Introini, M.V.; Lorenzoli, M. [Politecnico di Milano, Dipartimento di Energia, via La Masa 34, 20156 Milano (Italy); INFN—Milano, Via Celoria 16, 20133 Milano (Italy); Gómez-Ros, J.M. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); CIEMAT, Av. Complutense 40, 28040 Madrid (Spain); Sacco, D. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); INAIL—DIT, Via di Fontana Candida 1, 00040 Monteporzio Catone (Italy); Esposito, A.; Gentile, A.; Buonomo, B. [IFNF—LNF, via E. Fermi n. 40, 00044 Frascati, Roma (Italy); Palomba, M.; Grossi, A. [ENEA Triga RC-1C.R. Casaccia, via Anguillarese 301, 00060 S. Maria di Galeria, Roma (Italy)

    2015-04-21

    In the framework of NESCOFI@BTF and NEURAPID projects, active thermal neutron detectors were manufactured by depositing appropriate thickness of {sup 6}LiF on commercially available windowless p–i–n diodes. Detectors with different radiator thickness, ranging from 5 to 62 μm, were manufactured by evaporation-based deposition technique and exposed to known values of thermal neutron fluence in two thermal neutron facilities exhibiting different irradiation geometries. The following properties of the detector response were investigated and presented in this work: thickness dependence, impact of parasitic effects (photons and epithermal neutrons), linearity, isotropy, and radiation damage following exposure to large fluence (in the order of 10{sup 12} cm{sup −2})

  20. Analysis of air particulate matter in Teflon trademark and quartz filters by short-irradiation, epithermal-neutron activation with Compton suppression

    International Nuclear Information System (INIS)

    This work aimed at developing methodologies to characterize the elemental composition of air particulate matter (APM) collected in Portugal, at an urban area (Lisboa, mainland Portugal) and at a remote location (Terceira island, Azores, Portugal). The Azores' collections were based on quartz filters; Teflon trademark filters were used at the urban area. The main components of Teflon trademark and quartz filters are fluorine and silica, respectively, the latter featuring higher levels of elements in the blanks. Al and Ti are reduced to null values when the blanks are subtracted. Epithermal short irradiation associated to Compton suppression in the measurement allowed the determination of a set of elements potentially representative of important emission sources: seaspray (Cl, Br, Na, Mg), fuel burning (V), incineration (Cl), soil resuspension (Mg, Mn, Na, U, V), and traffic (Br, Mn). The analysis was fast due to the use of an automatic system. In some cases, the same element had different origins in the urban and remote oceanic areas. (orig.)

  1. Estimation of total as well as bioaccessible levels and average daily dietary intake of iodine from Japanese edible seaweeds by epithermal neutron activation analysis

    International Nuclear Information System (INIS)

    An epi-thermal instrumental neutron activation analysis (EINAA) method in conjunction with Compton suppression spectrometry (EINAA-CSS) was used for the determination of total iodine in eight different species of edible seaweeds from Japan. This method gave an absolute detection limit of about 2 μg. The accuracy of the method was evaluated using various reference materials and found to be generally in agreement within ±6% of the certified values. The longitudinal distributions of iodine at different growing stages in Japanese sea mustard and tangle seaweeds were investigated. For a 150-cm-high tangle, the highest concentration (5,360 mg/kg) of iodine was found at the root, then decreased slowly to 780 mg/kg in the middle portion (60-75 cm), and increased to 2,300 mg/kg at the apex. On the other hand, for a 190-cm-high sea mustard the highest levels of iodine were found both at the roots (164 mg/kg) and apex (152 mg/kg) with lower values (98 mg/kg) in the middle section. In order to estimate the bioaccessible fraction of iodine, seaweeds were digested by an in vitro enzymolysis method, dietary fibre separated from residue, and both fractions analyzed by EINAA-CSS. The average daily dietary intakes of total (0.14 mg) as well as bioaccessible fraction (0.12 mg) of iodine from the consumption of sea mustards were estimated. (author)

  2. Bulk Analysis Method of Gold Determination in Ores Using Epithermal Neutrons of Electron Accelerator Microtron MT-22

    CERN Document Server

    Gerbish, Sh; Baatarkhuu, D; Ganbold, G; Belov, A G

    2004-01-01

    Bulk analysis method of gold determination in ores by Instrumental Neutron Activation Analysis (INAA) is described. The powder (100-200 mesh) samples were irradiated in Cd foils of 1 mm thick with photo-neutrons at the Microtron MT-22 of the Nuclear Research Center, Mongolian State University (Ulaanbaatar). The sensitivity of 0.1 mg/kg Au can be obtained using 30-50 g samples and irradiation time of 1-2 h.

  3. Bulk analysis method of gold determination in ores using epithermal neutrons of electron accelerator microtron MT-22

    International Nuclear Information System (INIS)

    Bulk analysis method of gold determination in ores by Instrumental Neutron Activation Analysis (INAA) is described. The powder (100-200 mesh) samples were irradiated in Cd foils of 1 mm thick with photo-neutrons at the Microtron MT-22 of the Nuclear Research Center, Mongolian State University (Ulaanbaatar). The sensitivity of 0.1 mg/kg Au can be obtained using 30-50 g samples and irradiation time of 1-2 h

  4. The possibility existence of volatile compounds in the area of NSR S5 spot of local suppression of epithermal neutron flux in the South Pole region of the Moon.

    Science.gov (United States)

    Feoktistova, Ekaterina

    2016-07-01

    6 statistically significant areas in which it was recorded a lower value of the flow of epithermal neutrons was found in the polar regions of the moon according to LEND: 5 areas are located in the south polar region (the area NSR S1 - 5 [1]) and one (area NSR N1[1]) to the north. One of these areas - the area NSR S5 - is located in the landing sector Luna - Globe mission [2], the launch of which is planned by Russian Space Agency in 2018. In this paper, we investigated the temperature regime, illumination conditions and the possibility of the existence of deposits of volatile compounds in this area. To study we selected a number of substances was detected in the LCROSS impact site in the crater Cabeus, particularly compounds such as H2O, CO2, SO2, CH3OH, NH3, C2H4, H2S, CH4 · 5.75H2O and CO · 5.75H2O [3]. We divided the area of NSR S5 spot into a grid with a number of elements. Step in longitude grid was 0.15 degrees, a step in latitude 0.05 degrees. The total number of the elements of the area of the crater is 36000. The height, slope and orientation of each element were calculated based on a LOLA DEM [4] using an algorithm described in [5]. Our results show that the compounds of deposits such as H2O, CO2, SO2, CH3OH, NH3, C2H4, H2S, CH4 · 5.75H2O and CO · 5.75H2O may exist in NSR S5. Thus, the local suppression the epithermal neutron flux in this region may be due to the presence of hydrogen-containing compounds deposits. [1] Mitrofanov et al. (2012) JGR 117, E003956 [2] Ivanov et al. (2014) Solar System Res. 48, 391 - 402 [3] Colaprete et al. (2010) Science 330, 463-468 [4] http://wwwpds.wustl.edu/ [5] Zevenbergen, L.W., Thorne (1987) Earth Surface Processes and Landforms 12(1), 47-56.

  5. Polysiloxane based neutron detectors

    OpenAIRE

    Dalla Palma, Matteo

    2016-01-01

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

  6. Research of accelerator-based neutron source for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Background: 7Li (p, n) reaction of high neutron yield and low threshold energy has become one of the most important neutron generating reactions for Accelerator-based Boron Neutron Capture Therapy (BNCT). Purpose Focuses on neutron yield and spectrum characteristics of this kind of neutron generating reaction which serves as an accelerator-based neutron source and moderates the high energy neutron beams to meet BNCT requirements. Methods: The yield and energy spectrum of neutrons generated by accelerator-based 7Li(p, n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are researched using the Monte Carlo code-MCNPX2.5.0. And the energy and angular distribution of differential neutron yield by 2.5-MeV incident proton are also given in this part. In the following part, the character of epithermal neutron beam generated by 2.5-MeV incident protons is moderated by a new-designed moderator. Results: Energy spectra of neutrons generated by accelerator-based 7Li(p, n) reaction with incident proton energy from 1.9 MeV to 3.0 MeV are got through the simulation and calculation. The best moderator thickness is got through comparison. Conclusions: Neutron beam produced by accelerator-based 7Li(p, n) reaction, with the bombarding beam of 10 mA and the energy of 2.5 MeV, can meet the requirement of BNCT well after being moderated. (authors)

  7. Cs-137 geochronology, epithermal neutron activation analysis, and principal component analysis of heavy metals pollution of the Black Sea anoxic continental shelf sediments

    Science.gov (United States)

    Duliu, O. G.; Cristache, C.; Oaie, G.; Culicov, O. A.; Frontasyeva, M. V.

    2009-04-01

    Anthropogenic Cs-137 Gamma-ray Spectroscopy assay (GrSA) performed at the National Institute of Research and Development for Physics and Nuclear Engineering - Bucharest (Romania) in correlation with Epithermal Neutrons Activation Analysis (ENAA) performed at the Joint Institute of Nuclear Researches - Dubna (Russia) were used to investigate a 50 cm core containing unconsolidated sediments collected at a depth of 600 m off Romanian town of Constantza, located in the anoxic zone of the Black Sea Continental Shelf. A digital radiography showed the presence of about 265 distinct laminae, 1 to 3 mm thick, a fact attesting a stationary sedimentary process, completely free of bioturbation. After being radiographed, the core was sliced into 45 segments whose thickness gradually increased from 0.5 to 5 cm, such that the minimum thickness corresponded to the upper part of the core. From each segment two aliquots of about 0.5 g and 50 g were extracted for subsequent ENAA and Cs-137 GrSA. The Cs-137 vertical profile evidenced two maxima, one of them was very sharp and localized at a depth of 1 cm and the other very broad, almost undistinguished at about 8 cm depth, the first one being attributed to 1986 Chernobyl accident. Based on these date, we have estimated a sedimentation ratio of about 0.5 mm/year, value taken as reference for further assessment of recent pollution history. By means of ENAA we have determined the vertical content of five presumed pollutants, e.i. Zn, As, Br, Sn and Sb and of Sc, as natural, nonpolluting element. In the first case, all five elements presented a more or less similar vertical profile consisting of an almost exponential decrease for the first 10 cm below sediment surface followed by a plateau until the core base, i.e. 50 cm below surface, dependency better described by the equation: c(z) = c0 [1+k exp (-z/Z)] (1) where: where c(z) represents the concentration vertical profile; z represents depth (in absolute value); c0 represents the plateau

  8. Pulsed neutron porosity logging

    International Nuclear Information System (INIS)

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

  9. Measurements in quasi-monoenergetic neutron beams at the EC-IRMM Van der Graaf accelerator for calibration of the UAB PADC based neutron dosimeter

    Energy Technology Data Exchange (ETDEWEB)

    Domingo, C., E-mail: carles.domingo@uab.ca [Grup de Fisica de les Radiacions, Departament de Fisica, Edifici C, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Garcia-Fuste, M.J.; Amgarou, K.; Morales, E.; Castelo, J. [Grup de Fisica de les Radiacions, Departament de Fisica, Edifici C, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)

    2009-10-15

    The UAB PADC based neutron dosimeter was designed to have similar dose responses for thermal and for fast neutrons. A set of calibrations with ISO neutron sources and the realistic SIGMA neutron field at IRSN Cadarache showed this behaviour. Nevertheless, a noticeable decrease of the response to epithermal neutrons is expected because of the small values of cross sections for neutrons at this energy range. The EC NUDAME program gave the opportunity to expose several units of our dosimeter to quasi-monoenergetic beams at the IRMM Van der Graaf accelerator for calibration purposes. The revision of the IRSN Cadarache values with an improved uncertainty treatment and the results of the calibration at IRMM Van der Graaf, in relation to the reference values of the neutron source term obtained using our Bonner sphere spectrometer, are presented in this work.

  10. Detailed spatial measurements and Monte Carlo analysis of the transportation phenomena of thermal and epithermal neutrons from the 12-GeV proton transport line to an access maze

    International Nuclear Information System (INIS)

    In order to investigate the neutron transportation from a beam-line tunnel to an access maze at a 12-GeV proton accelerator, we measured the spatial distribution of thermal and epithermal neutrons by using the Au activation method in detail. Gold foils were placed at about 70 positions in the maze in the case of the insertion (or extraction) of a copper target of 1 mm thickness into (or from) the beam axis in front of the maze. After the end of accelerator operation, relative activities of the Au foils were simultaneously measured by using an imaging plate technique and the radioactivity of one reference foil was also measured with a HPGe detector to convert to the absolute activities of all foils. It was found that the neutrons reach to the depth of the maze in the case of the insertion of the copper target. This result reflects higher proportion of high-energy particles from the copper target to that from other beam loss points and high-energy particles become the successive source of low-energy neutrons. Furthermore, it was found that several circumstances such as door walls and electric wire cables obviously affect the absorption effect of thermal neutrons. The reaction rates obtained in this study were also used for the benchmark of the Monte Carlo simulation code, MARS15 (version of February 2008). The results of the MARS15 calculations precisely reproduced experimental results and significant effects of the electric wire cables and door walls

  11. An Analysis Technique for Active Neutron Multiplicity Measurements Based on First Principles

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Louise G [Los Alamos National Laboratory; Goddard, Braden [Los Alamos National Laboratory; Charlton, William S [Los Alamos National Laboratory; Peerani, Paolo [European Commission, EC-JRC-IPSC

    2012-08-13

    Passive neutron multiplicity counting is commonly used to quantify the total mass of plutonium in a sample, without prior knowledge of the sample geometry. However, passive neutron counting is less applicable to uranium measurements due to the low spontaneous fission rates of uranium. Active neutron multiplicity measurements are therefore used to determine the {sup 235}U mass in a sample. Unfortunately, there are still additional challenges to overcome for uranium measurements, such as the coupling of the active source and the uranium sample. Techniques, such as the coupling method, have been developed to help reduce the dependence of calibration curves for active measurements on uranium samples; although, they still require similar geometry known standards. An advanced active neutron multiplicity measurement method is being developed by Texas A&M University, in collaboration with Los Alamos National Laboratory (LANL) in an attempt to overcome the calibration curve requirements. This method can be used to quantify the {sup 235}U mass in a sample containing uranium without using calibration curves. Furthermore, this method is based on existing detectors and nondestructive assay (NDA) systems, such as the LANL Epithermal Neutron Multiplicity Counter (ENMC). This method uses an inexpensive boron carbide liner to shield the uranium sample from thermal and epithermal neutrons while allowing fast neutrons to reach the sample. Due to the relatively low and constant fission and absorption energy dependent cross-sections at high neutron energies for uranium isotopes, fast neutrons can penetrate the sample without significant attenuation. Fast neutron interrogation therefore creates a homogeneous fission rate in the sample, allowing for first principle methods to be used to determine the {sup 235}U mass in the sample. This paper discusses the measurement method concept and development, including measurements and simulations performed to date, as well as the potential

  12. Determining and reporting the doses in the treatments of glioma patients in the epithermal neutron beam at the Finnish BNCT facility (FIR 1)

    International Nuclear Information System (INIS)

    The clinical trials of glioma patients at the Finnish boron neutron capture therapy (BNCT) facility (FiR 1) started in May 1999. The doses of the patient in tumour, target volume and sensitive tissues are calculated individually. The calculated doses are calibrated to the reference monitor units according to the ratio of the independently measured and calculated 197Au(n,g) reactions rates at the depth of 20 mm on the central axis of a cylindrical PMMA phantom chosen as the reference geometry. Absorbed doses to the head and body are monitored individually using in vivo dosimeters. In BNCT the total dose is the weighted sum of the absorbed doses originating from the neutron and gamma interactions in tissues. The material compositions of the head model for the neutron-gamma transport calculation and kerma factors are based on the ICRU report 46. The doses in the clinical research of BNCT should be reported in such a way that the doses are comparable, traceable and can be recalculated, if underlying information, like weighting factors for dose components, are replaced by new ones. The minimum, maximum, average and reference doses are reported for the tumour, target and normal brain. In addition to the total weighted doses the dose components (boron, gamma, nitrogen and fast neutron dose), weighting factors and estimated boron concentration in these tissues are reported. There are no international recommendations available for BNCT dose calculation or reporting. Therefore the BNCT doses reported in the literature may not be comparable and a careless use of values can lead to over- or underdosing. There is an obvious need for standardisation in the medical application of BNCT. In this paper the methods of dose calculation and reporting of the glioma patients at FiR 1 are described. (author)

  13. Fluid evolution in a volcanic-hosted epithermal carbonate-base metal-gold vein system: Alto de la Blenda, Farallón Negro, Argentina

    Science.gov (United States)

    Márquez-Zavalía, M. Florencia; Heinrich, Christoph A.

    2016-03-01

    Alto de la Blenda is a ˜6.6-Ma intermediate-sulphidation epithermal vein system in the Farallón Negro Volcanic Complex, which also hosts the 7.1-Ma porphyry-Cu-Au deposit of Bajo de la Alumbrera. The epithermal vein system is characterised by a large extent and continuity (2 km × 400 m open to depth × 6 m maximum width) and an average gold grade of ˜8 g/t. The vein is best developed within an intrusion of a fine-grained equigranular monzonite, interpreted as the central conduit of a stratovolcano whose extrusive activity ended prior to porphyry-Cu-Au emplacement at Bajo de la Alumbrera, which is in turn cut by minor epithermal veins. The Alto de la Blenda vein consists predominantly of variably Mn-rich carbonates and quartz, with a few percent of pyrite, sphalerite, galena and other sulphide and sulphosalt minerals. Four phases of vein opening, hydrothermal mineralisation and repeated brecciation can be correlated between different vein segments. Stages 2 and 3 contain the greatest fraction of sulphide and gold. They are separated by the emplacement of a polymictic breccia containing clasts of quartz feldspar porphyry as well as basement rocks. Fluid inclusions in quartz related to stages 2 to 4 are liquid rich with 2-4 wt% NaCl(eq). They homogenise between 160 and 300 °C, with very consistent values within each assemblage. Vapour inclusions are practically absent in the epithermal vein. Quartz fragments in the polymictic breccia contain inclusions of intermediate to vapour-like density and similar low salinity (˜3 wt% NaCl(eq)), besides rare brine inclusions containing halite. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of epithermal inclusions indicate high concentrations of K, Fe, As, Sb, Cs, and Pb that significantly vary within and through subsequent vein stages. Careful consideration of detection limits for individual inclusions shows high gold concentrations of ˜0.5 to 3 ppm dissolved in the ore fluid, which

  14. Neutron transport study of a beam port based dynamic neutron radiography facility

    Science.gov (United States)

    Khaial, Anas M.

    Neutron radiography has the ability to differentiate between gas and liquid in two-phase flow due both to the density difference and the high neutron scattering probability of hydrogen. Previous studies have used dynamic neutron radiography -- in both real-time and high-speed -- for air-water, steam-water and gas-liquid metal two-phase flow measurements. Radiography with thermal neutrons is straightforward and efficient as thermal neutrons are easier to detect with relatively higher efficiency and can be easily extracted from nuclear reactor beam ports. The quality of images obtained using neutron radiography and the imaging speed depend on the neutron beam intensity at the imaging plane. A high quality neutron beam, with thermal neutron intensity greater than 3.0x 10 6 n/cm2-s and a collimation ratio greater than 100 at the imaging plane, is required for effective dynamic neutron radiography up to 2000 frames per second. The primary objectives of this work are: (1) to optimize a neutron radiography facility for dynamic neutron radiography applications and (2) to investigate a new technique for three-dimensional neutron radiography using information obtained from neutron scattering. In this work, neutron transport analysis and experimental validation of a dynamic neutron radiography facility is studied with consideration of real-time and high-speed neutron radiography requirements. A beam port based dynamic neutron radiography facility, for a target thermal neutron flux of 1.0x107 n/cm2-s, has been analyzed, constructed and experimentally verified at the McMaster Nuclear Reactor. The neutron source strength at the beam tube entrance is evaluated experimentally by measuring the thermal and fast neutron fluxes using copper activation flux-mapping technique. The development of different facility components, such as beam tube liner, gamma ray filter, beam shutter and biological shield, is achieved analytically using neutron attenuation and divergence theories. Monte

  15. Diurnally Varying Hydrogen Volatiles or Regolith Temperature? Mare and Highlands Studies of the Moon's Diurnally Modulating Epithermal Neutron Flux Using LRO's LEND, Diviner, and LOLA Instruments

    Science.gov (United States)

    McClanahan, T. P.; LEND Team; Parsons, A. M.; Williams, J. P.; Mazarico, E.

    2015-10-01

    In this study we seek to discriminate the source of variation that is diurnally modulating the Moon's neutron emission flux. We characterize the neutron emission flux from the topography in the northern mare and highlands regions.

  16. Fusion Based Neutron Sources for Security Applications: Neutron Techniques

    OpenAIRE

    Albright, S.; Seviour, Rebecca

    2014-01-01

    The current reliance on X-Rays and intelligence for na- tional security is insufficient to combat the current risks of smuggling and terrorism seen on an international level. There are a range of neutron based security techniques which have the potential to dramatically improve national security. Neutron techniques can be broadly grouped into neutron in/neutron out and neutron in/photon out tech- niques. The use of accelerator based fusion devices will potentially enable to wide spread applic...

  17. Design of a plate type fuel based - low power medical reactor for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Machine) system composed of 12 CPU(intel celeron 300A). Optimized moderation/filter is calculated from fixed source calculation and that configuration is AlF3, Al, Ti, Cd, Bi, and Air. The proposed reactor provides an East-West regional epithermal neutron beam of 1.67x1010 nepi/cm2·s intensity with low contamination by fast neutrons (2.2x10-13 Gy·cm2/nepi) and gamma rays (1.4x10-13Gy·cm2/nepi) and a North-South regional epithermal neutron beam of 1.29x1010nepi/cm2·s intensity with low contamination by fast neutrons (3.0x10-13 Gy·cm2/nepi) and gamma rays (2.0x10-13 Gy·cm2/nepi). The proposed design surpasses the neutronic design goals for in-air beam performance, providing epithermal neutron beams with high intensity(>1.0x1010n/cm2·sec) and high quality in both East-West region and North-South region. Independent neutron beam shutters control beam delivery to the patient and two control assemblies effectively can shutdown the reactor. A separate set of 4 control plates will control the reactivity in the case of emergency as an auxiliary device. With a low operating power of 300kW the heat generated in the core can be removed efficiently by natural convection through a pool of light water and proper cooler. Consequently, the plate fuel based-300kW reactor for BNCT is capable of safely delivering treatments in a few minutes with a relatively low cost and the reactor could be constructed at a hospital in metropolitan area

  18. 9Be(d,n)10B-based neutron sources for BNCT

    International Nuclear Information System (INIS)

    In the frame of accelerator-based BNCT, the 9Be(d,n)10B reaction was investigated as a possible source of epithermal neutrons. In order to determine the configuration in terms of bombarding energy, target thickness and Beam Shaping Assembly (BSA) design that results in the best possible beam quality, a systematic optimization study was carried out. From this study, the optimal configuration resulted in tumor doses ≥40 Gy-Eq, with a maximum value of 51 Gy-Eq at a depth of about 2.7 cm, in a 60 min treatment. The optimal configuration was considered for the treatment planning assessment of a real Glioblastoma Multiforme case. From this, the resulted dose performances were comparable to those obtained with an optimized 7Li(p,n)-based neutron source, under identical conditions and subjected to the same clinical protocol. - Highlights: • Study of the 9Be(d,n)10B reaction as a source of epithermal neutrons for BNCT. • Evaluation of the optimal configuration of target thickness, deuteron energy and BSA design. • Computational dose assessment for brain tumor treatments using the MCNP code. • Treatment planning assessment of a particular clinical Glioblastoma Multiforme case. • Dose performances were comparable to those obtained with an optimized 7Li(p,n)-based source

  19. Current progress and future prospects of the VITA based neutron source

    International Nuclear Information System (INIS)

    At the BINP, a pilot accelerator based epithermal neutron source is now in use. Most recent investigations on the facility are related with studying the dark current, X-ray radiation measuring, optimization of H−-beam injection and new gas stripping target calibrating. The results of these studies, ways of providing stability to the accelerator are presented and discussed, as well as the ways of creating the therapeutic beam and strategies of applying the facility for clinical use. - Highlights: • We have increased proton current up to 2 mA. • VITA based neutron source is ready for in vitro investigations. • We proposed to use a orthogonal neutron beam for BNCT with “à la gantry” possibility

  20. Determination of neutron flux parameters at Apsara reactor for k0-NAA using Hogdahl and Westcott conventions

    International Nuclear Information System (INIS)

    In order to apply k0-based neutron activation analysis (k0-NAA) in general to all nuclides and especially to the nuclides following non l/v (n, γ) reactions, the neutron spectrum of E8 irradiation position of Apsara reactor has been characterized. Both Hogdahl and Westcott conventions were followed for the reaction rates. The parameters determined included epithermal neutron flux shape factor (α), subcadmium-to-epithermal neutron flux ratio (f), modified spectral index (MSI) r(α)√(Tn/T0), Westcott gLu(Tn)-factor, and absolute neutron temperature Tn. (author)

  1. MANTA. An Integral Reactor Physics Experiment to Infer the Neutron Capture Cross Sections of Actinides and Fission Products in Fast and Epithermal Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Youinou, Gilles Jean-Michel [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-10-01

    Neutron cross-sections characterize the way neutrons interact with matter. They are essential to most nuclear engineering projects and, even though theoretical progress has been made as far as the predictability of neutron cross-section models, measurements are still indispensable to meet tight design requirements for reduced uncertainties. Within the field of fission reactor technology, one can identify the following specializations that rely on the availability of accurate neutron cross-sections: (1) fission reactor design, (2) nuclear fuel cycles, (3) nuclear safety, (4) nuclear safeguards, (5) reactor monitoring and neutron fluence determination and (6) waste disposal and transmutation. In particular, the assessment of advanced fuel cycles requires an extensive knowledge of transuranics cross sections. Plutonium isotopes, but also americium, curium and up to californium isotope data are required with a small uncertainty in order to optimize significant features of the fuel cycle that have an impact on feasibility studies (e.g. neutron doses at fuel fabrication, decay heat in a repository, etc.). Different techniques are available to determine neutron cross sections experimentally, with the common denominator that a source of neutrons is necessary. It can either come from an accelerator that produces neutrons as a result of interactions between charged particles and a target, or it can come from a nuclear reactor. When the measurements are performed with an accelerator, they are referred to as differential since the analysis of the data provides the cross-sections for different discrete energies, i.e. σ(Ei), and for the diffusion cross sections for different discrete angles. Another approach is to irradiate a very pure sample in a test reactor such as the Advanced Test Reactor (ATR) at INL and, after a given time, determine the amount of the different transmutation products. The precise characterization of the nuclide densities before and after

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

    Science.gov (United States)

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

    2016-07-01

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

  3. Pulsed neutron porosity logging system

    International Nuclear Information System (INIS)

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

  4. An in-phantom comparison of neutron fields for BNCT

    International Nuclear Information System (INIS)

    Previously, the authors have developed the in-phantom neutron field assessment parameters T and D (Tumor) for the evaluation of epithermal neutron fields for use in BNCT. These parameters are based on an energy-spectrum-dependent neutron normal-tissue RBE and the treatment planning methodology of Gahbauer and his co-workers, which includes the effects of dose fractionation. In this paper, these neutron field assessment parameters were applied to The Ohio State University (OSU) design of an Accelerator Based Neutron Source (ABNS) (hereafter called the OSU-ABNS) and the Brookhaven Medical Research Reactor (BMRR) epithermal neutron beam (hereafter called the BMRR-ENB), in order to judge the suitability of the OSU-ABNS for BNCT. The BMRR-ENB was chosen as the basis for comparison because it is presently being used in human clinical trials of BNCT and because it is the standard to which other neutron beams are most often compared

  5. Accelerator based neutron source for neutron capture therapy

    International Nuclear Information System (INIS)

    Full text: The Budker Institute of Nuclear Physics (Novosibirsk) and the Institute of Physics and Power Engineering (Obninsk) have proposed an accelerator based neutron source for neutron capture and fast neutron therapy for hospital. Innovative approach is based upon vacuum insulation tandem accelerator (VITA) and near threshold 7Li(p,n)7Be neutron generation. Pilot accelerator based neutron source for neutron capture therapy is under construction now at the Budker Institute of Nuclear Physics, Novosibirsk, Russia. In the present report, the pilot facility design is presented and discussed. Design features of facility components are discussed. Results of experiments and simulations are presented. Complete experimental tests are planned by the end of the year 2005

  6. Epithermal beam development at the BMRR [Brookhaven Medical Research Reactor]: Dosimetric evaluation

    International Nuclear Information System (INIS)

    The utilization of an epithermal neutron beam for neutron capture therapy (NCT) is desirable because of the increased tissue penetration relative to a thermal neutron beam. Over the past few years, modifications have been and continue to be made at the Brookhaven Medical Research Reactor (BMRR) by changing its filter components to produce an optimal epithermal beam. An optimal epithermal beam should contain a low fast neutron contamination and no thermal neutrons in the incident beam. Recently a new moderator for the epithermal beam has been installed at the epithermal port of the BMRR and has accomplished this task. This new moderator is a combination of alumina (Al2O3) bricks and aluminum (Al) plates. A 0.51 mm thick cadmium (Cd) sheet has reduced the thermal neutron intensity drastically. Furthermore, an 11.5 cm thick bismuth (Bi) plate installed at the port surface has reduced the gamma dose component to negligible levels. Foil activation techniques have been employed by using bare gold and cadmium-covered gold foil to determine thermal as well as epithermal neutron fluence. Fast neutron fluence has been determined by indium foil counting. Fast neutron and gamma dose in soft tissue, free in air, is being determined by the paired ionization chamber technique, using tissue equivalent (TE) and graphite chambers. Thermoluminescent dosimeters (TLD-700) have also been used to determine the gamma dose independently. This paper describes the methods involved in the measurements of the above mentioned parameters. Formulations have been developed and the various corrections involved have been detailed. 12 refs

  7. Boron neutron capture therapy design calculation of a 3H(p,n reaction based BSA for brain cancer setup

    Directory of Open Access Journals (Sweden)

    Bassem Elshahat

    2015-09-01

    Full Text Available Purpose: Boron neutron capture therapy (BNCT is a promising technique for the treatment of malignant disease targeting organs of the human body. Monte Carlo simulations were carried out to calculate optimum design parameters of an accelerator based beam shaping assembly (BSA for BNCT of brain cancer setup.Methods: Epithermal beam of neutrons were obtained through moderation of fast neutrons from 3H(p,n reaction in a high density polyethylene moderator and a graphite reflector. The dimensions of the moderator and the reflector were optimized through optimization of epithermal / fast neutron intensity ratio as a function of geometric parameters of the setup. Results: The results of our calculation showed the capability of our setup to treat the tumor within 4 cm of the head surface. The calculated peak therapeutic ratio for the setup was found to be 2.15. Conclusion: With further improvement in the polyethylene moderator design and brain phantom irradiation arrangement, the setup capabilities can be improved to reach further deep-seated tumor.

  8. Observation of Neutron Skyshine from an Accelerator Based Neutron Source

    Science.gov (United States)

    Franklyn, C. B.

    2011-12-01

    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 >1011 nṡs-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.

  9. Potentialities of the molten salt reactor concept for a sustainable nuclear power production based on thorium cycle in epithermal spectrum

    International Nuclear Information System (INIS)

    In the case of a significant nuclear contribution to world energy needs, the problem of present nuclear waste management pose the sustainability of the PWR fuel cycle back into question. Studies on storage and incineration of these wastes should therefore go hand in hand with studies on innovative systems dedicated to a durable nuclear energy production, as reliable, clean and safe as possible. We are here interested in the concept of molten salt reactor, whose fuel is liquid. This particularity allows an online pyrochemical reprocessing which gives the possibility to overcome some neutronic limits. In the late sixties, the MSBR (Molten Salt Breeder Reactor) project of a graphite-moderated fluoride molten salt reactor proved thus that breeding is attainable with thorium in a thermal spectrum, provided that the online reprocessing is appropriate. By means of simulation tools developed around the Monte Carlo code MCNP, we first re-evaluate the performance of a reference system, which is inspired by the MSBR project. The complete study of the pre-equilibrium transient of this 2,500 MWth reactor, started with 232Th/233U fuel, allows us to validate our reference choices. The obtained equilibrium shows an important reduction of inventories and induced radio-toxicities in comparison with the other possible fuel cycles. The online reprocessing is efficient enough to make the system breed, with a doubling time of about thirty years at equilibrium. From the reference system, we then test different options in terms of neutron economy, transmutation and control of reactivity. We find that the online reprocessing brings most of its flexibility to this system, which is particularly well adapted to power generation with thorium. The study of transition scenarios to this fuel cycle quantifies the limits of a possible deployment from the present French power stock, and finally shows that a rational management of the available plutonium would be necessary in any case. (author)

  10. Applicability of near-infrared hyperspectral imagery (NIR-HI) for sensor based sorting of an epithermal Au-Ag ore

    NARCIS (Netherlands)

    Dalm, M.; Buxton, M.W.N.; Van Ruitenbeek, F.J.A.

    2015-01-01

    In the presented study test work was performed with near-infrared hyperspectral imagery (NIR-HI) on 36 ore samples from a South-American epithermal Au-Ag mine. The aim of the test work was to investigate if NIR-HI provides information about the alteration mineralogy of samples that can be used to pr

  11. Use of accelerator based neutron sources

    International Nuclear Information System (INIS)

    With the objective of discussing new requirements related to the use of accelerator based neutron generators an Advisory Group meeting was held in October 1998 in Vienna. This meeting was devoted to the specific field of the utilization of accelerator based neutron generators. This TECDOC reports on the technical discussions and presentations that took place at this meeting and reflects the current status of neutron generators. The 14 MeV neutron generators manufactured originally for neutron activation analysis are utilised also for nuclear structure and reaction studies, nuclear data acquisition, radiation effects and damage studies, fusion related studies, neutron radiography

  12. Radio-isotopic neutron sources for industrial applications and basic research

    International Nuclear Information System (INIS)

    CNIF2 is an irradiation facility based on an Am-Be (b, n) source with present activity of about 175 GBq results in a neutron yield of about 1.04*107 n/s. The facility provides fast and epi-thermal neutrons as well. The aim of the present work is to develop methods able to use neutron activation analysis to estimate the hydrogen content in bulk samples through neutron reflection and transmission processes.

  13. ETOGM: epithermal cross section generation code using ENDF/B data

    International Nuclear Information System (INIS)

    ETOGM processes ENDF/B FORMAT data to produce a master epithermal library containing multigroup cross sections, resolved and unresolved resonance parameters, and a scattering matrix for up to 100 materials of interest in reactor design calculations. The epithermal energy range may be divided into as many as 127 groups, and a weighting function may either be input or calculated by the code for use in calculating average group coefficients. Resonance contributions from thermal and negative energy resolved resonances, as well as infinite-dilute corrections in the epithermal range, are added to the appropriate smooth cross sections. Resolved and unresolved resonance parameters are tabulated when applicable. A combined inelastic-(n,2n) scattering matrix is calculated from secondary neutron energy distribution data. A fission spectrum is computed for each fissionable material. The master epithermal library is generated, updated, and edited by the ETOGM program

  14. A neutron detector based on microchannel plates

    International Nuclear Information System (INIS)

    We propose a large-area neutron detector design based on microchannel plates (MCPs). Two characteristics of the MCP make it ideal as a high-rate neutron detector: (1) its signals can have a very fast rise time, and (2) it can count at a high rate. The MCP-based detector could use both the high-voltage power supplies and the readout electronics designed for a neutron detector based on the multiwire proportional chamber (MWPC)

  15. Tests of time reversal in neutron-nucleus scattering

    International Nuclear Information System (INIS)

    Experiments to test time-reversal invariance are discussed. The experiments are based on observables constructed from the momentum and spin vectors of epithermal neutrons and from the spin of an aligned or polarized target. It is shown that the proposed tests are detailed balance tests of time-reversal invariance. The status of the experiments is briefly reviewed. 14 refs., 5 figs

  16. High sensitivity MOSFET-based neutron dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Fragopoulou, M.; Konstantakos, V. [Aristotle University of Thessaloniki, Physics Department, 54124 Thessaloniki (Greece); Zamani, M., E-mail: zamani@physics.auth.g [Aristotle University of Thessaloniki, Physics Department, 54124 Thessaloniki (Greece); Siskos, S.; Laopoulos, T. [Aristotle University of Thessaloniki, Physics Department, 54124 Thessaloniki (Greece); Sarrabayrouse, G. [CNRS, LAAS, 7 avenue du colonel Roche, F-31077 Toulouse (France); Universite de Toulouse, UPS, INSA, INP, ISAE, LAAS, F-31077 Toulouse (France)

    2010-09-21

    A new dosemeter based on a metal-oxide-semiconductor field effect transistor sensitive to both neutrons and gamma radiation was manufactured at LAAS-CNRS Laboratory, Toulouse, France. In order to be used for neutron dosimetry, a thin film of lithium fluoride was deposited on the surface of the gate of the device. The characteristics of the dosemeter, such as the dependence of its response to neutron dose and dose rate, were investigated. The studied dosemeter was very sensitive to gamma rays compared to other dosemeters proposed in the literature. Its response in thermal neutrons was found to be much higher than in fast neutrons and gamma rays.

  17. A QUANTITATIVE COMPARISON OF LUNAR ORBITAL NEUTRON DATA

    International Nuclear Information System (INIS)

    Data from the Lunar Exploration Neutron Detector (LEND) Collimated Sensors for Epithermal Neutrons (CSETN) are used in conjunction with a model based on results from the Lunar Prospector (LP) mission to quantify the extent of the background in the LEND CSETN. A simple likelihood analysis implies that at least 90% of the lunar component of the LEND CSETN flux results from high-energy epithermal (HEE) neutrons passing through the walls of the collimator. Thus, the effective FWHM of the LEND CSETN field of view is comparable to that of the omni-directional LP Neutron Spectrometer. The resulting map of HEE neutrons offers the opportunity to probe the hydrogen abundance at low latitudes and to provide constraints on the distribution of lunar water.

  18. A QUANTITATIVE COMPARISON OF LUNAR ORBITAL NEUTRON DATA

    Energy Technology Data Exchange (ETDEWEB)

    Eke, V. R. [Institute for Computational Cosmology, Department of Physics, Durham University, Durham, DH1 3LE (United Kingdom); Teodoro, L. F. A. [BAER, Planetary Systems Branch, Space Sciences and Astrobiology Division, MS 245-3, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Lawrence, D. J. [Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723 (United States); Elphic, R. C. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Feldman, W. C., E-mail: v.r.eke@durham.ac.uk [Planetary Science Institute, Tucson, AZ 85719 (United States)

    2012-03-01

    Data from the Lunar Exploration Neutron Detector (LEND) Collimated Sensors for Epithermal Neutrons (CSETN) are used in conjunction with a model based on results from the Lunar Prospector (LP) mission to quantify the extent of the background in the LEND CSETN. A simple likelihood analysis implies that at least 90% of the lunar component of the LEND CSETN flux results from high-energy epithermal (HEE) neutrons passing through the walls of the collimator. Thus, the effective FWHM of the LEND CSETN field of view is comparable to that of the omni-directional LP Neutron Spectrometer. The resulting map of HEE neutrons offers the opportunity to probe the hydrogen abundance at low latitudes and to provide constraints on the distribution of lunar water.

  19. Global Maps of Lunar Neutron Fluxes from the LEND Instrument

    Science.gov (United States)

    Litvak, M. L.; Mitrofanov, I. G.; Sanin, A.; Malakhov, A.; Boynton, W. V.; Chin, G.; Droege, G.; Evans, L. G.; Garvin, J.; Golovin, D. V.; Harshman, K.; McClanahan, T. P.; Mokrousov, M. I.; Mazarico, E.; Milikh, G.; Neumann, G.; Sagdeev, R.; Smith, D. E.; Starr, R.; Zuber, M. T.

    2012-01-01

    The latest neutron spectrometer measurements with the Lunar Exploration Neutron Detector (LEND) onboard the Lunar Reconnaissance Orbiter (LRO) are presented. It covers more than 1 year of mapping phase starting on 15 September 2009. In our analyses we have created global maps showing regional variations in the flux of thermal (energy range 0.5 MeV), and compared these fluxes to variances in soil elemental composition, and with previous results obtained by the Lunar Prospector Neutron Spectrometer (LPNS). We also processed data from LEND collimated detectors and derived a value for the collimated signal of epithermal neutrons based on the comparative analysis with the LEND omnidirectional detectors. Finally, we have compared our final (after the data reduction) global epithermal neutron map with LPNS data.

  20. Measurements of neutron flux in the RA reactor

    International Nuclear Information System (INIS)

    This report includes results of the following measurements performed at the RA reactor: thermal neutron flux in the experimental channels, epithermal and fast neutron flux, neutron flux in the biological shield, neutron flux distribution in the reactor cell

  1. 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)

  2. Dosimetry methods in boron neutron capture therapy

    International Nuclear Information System (INIS)

    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)

  3. Silicate rock and rock forming mineral neutron activation analysis

    International Nuclear Information System (INIS)

    A neutron-activation scheme for the determination of nine rare earths and other trace elements in various rock forming minerals (feldspars, ilmenite, magnetite, pyroxenes) and silicate rocks is presented. The procedure is based on three different irradiations involving three separate samples: - epithermal neutron irradiation (2 days) followed by nondestructive analysis; - thermal neutron irradiation (1 day) followed by instrumental analysis; - thermal neutron irradiation (1 week) followed by radiochemical analysis (precipitation, anion exchange separation, liquid-liquid extraction). Two USGS reference samples - granite G-2 and andesite AGV-1 - have been analysed in order to assess the accuracy of the proposed procedure. Our results agree with previous neutron-activation data. (orig.)

  4. Characterization of low power research reactor neutrons for the validation of k0-INAA standardization based on k0-IAEA software

    International Nuclear Information System (INIS)

    Channel Bsite2 of Ghana research reactor-1 has been characterized for k0-INAA application. Cadmium ratio and bare multi-monitor were used to determine flux parameters using 0.1%Au–Al, Fe, and Zr wire as flux monitors. The parameters determined were 18.36±1.91, 0.0479±0.012, 5.12×1011±0.42×1011 ncm−2 s−1, 2.74×1010±0.14×1010 ncm−2 s−1, 7.73×1010±0.16×1010 ncm−2 s−1 and 16.75±1.58, −0.034±0.0028, 4.28×1011±1.71×1011 ncm−2 s−1, 2.55×1010±0.15×1010 ncm−2 s−1 respectively for thermal-to-epithermal flux ratio, alpha, thermal neutron, epithermal neutron and fast neutron flux using cadmium ratio and multi-monitor method accordingly. The k0-INAA performance assessment based on z-score distributions showed most results within |z|0-INAA application. • Both bare and Cd-ratio method were used for the characterization. • α, f and thermal, epithermal and fast neutron flux values were found to agree largely with earlier reports. • We developed an irradiation method to detect and quantify up to 32 elements in plants, rock and lake sediment matrices. • The z-score analysis showed 90% of the data points within the range of |z|<2

  5. Conversion ratio in epithermal PWR, in thorium and uranium cycle

    International Nuclear Information System (INIS)

    Results obtained for the conversion ratio in PWR reactors with close lattices, operating in thorium and uranium cycles, are presented. The study of those reactors is done in an unitary fuel cell of the lattices with several ratios V sub(M)/V sub(F), considering only the equilibrium cycles and adopting a non-spatial depletion calculation model, aiming to simulate mass flux of reactor heavy elements in the reactor. The neutronic analysis and the cross sections generation are done with Hammer computer code, with one critical apreciation about the application of this code in epithermal systems and with modifications introduced in the library of basic data. (E.G.)

  6. Intermediate sulfidation epithermal mineralization of No. 4 anomaly of Golojeh deposit (N. Zanjan based on mineralography, alteration and ore fluid geochemistry features

    Directory of Open Access Journals (Sweden)

    Behzad Mehrab

    2014-04-01

    contents of galena, sphalerite and minor chalcopyrite and tennantite, low to moderate temperature and salinity of ore-bearing fluid, low depth of mineralization and Fe–bearing sphalerite features at the No. 4 anomaly of Golojeh deposit, are similar to those of intermediate sulfidation (IS epithermal base and precious metals vein–type deposit that probably might be related to Cu–Au porphyry system in depth.

  7. Compact ion chamber based neutron detector

    Science.gov (United States)

    Derzon, Mark S.; Galambos, Paul C.; Renzi, Ronald F.

    2015-10-27

    A directional neutron detector has an ion chamber formed in a dielectric material; a signal electrode and a ground electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; readout circuitry which is electrically coupled to the signal and ground electrodes; and a signal processor electrically coupled to the readout circuitry. The ion chamber has a pair of substantially planar electrode surfaces. The chamber pressure of the neutron absorbing material is selected such that the reaction particle ion trail length for neutrons absorbed by the neutron absorbing material is equal to or less than the distance between the electrode surfaces. The signal processor is adapted to determine a path angle for each absorbed neutron based on the rise time of the corresponding pulse in a time-varying detector signal.

  8. Ion chamber based neutron detectors

    Science.gov (United States)

    Derzon, Mark S; Galambos, Paul C; Renzi, Ronald F

    2014-12-16

    A neutron detector with monolithically integrated readout circuitry, including: a bonded semiconductor die; an ion chamber formed in the bonded semiconductor die; a first electrode and a second electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; and the readout circuitry which is electrically coupled to the first and second electrodes. The bonded semiconductor die includes an etched semiconductor substrate bonded to an active semiconductor substrate. The readout circuitry is formed in a portion of the active semiconductor substrate. The ion chamber has a substantially planar first surface on which the first electrode is formed and a substantially planar second surface, parallel to the first surface, on which the second electrode is formed. The distance between the first electrode and the second electrode may be equal to or less than the 50% attenuation length for neutrons in the neutron absorbing material filling the ion chamber.

  9. Advances in neutron based bulk explosive detection

    International Nuclear Information System (INIS)

    Neutron based explosive inspection systems can detect a wide variety of national security threats. The inspection is founded on the detection of characteristic gamma rays emitted as the result of neutron interactions with materials. Generally these are gamma rays resulting from thermal neutron capture and inelastic scattering reactions in most materials and fast and thermal neutron fission in fissile (e.g.235U and 239Pu) and fertile (e.g.238U) materials. Cars or trucks laden with explosives, drugs, chemical agents and hazardous materials can be detected. Cargo material classification via its main elements and nuclear materials detection can also be accomplished with such neutron based platforms, when appropriate neutron sources, gamma ray spectroscopy, neutron detectors and suitable decision algorithms are employed. Neutron based techniques can be used in a variety of scenarios and operational modes. They can be used as stand alones for complete scan of objects such as vehicles, or for spot-checks to clear (or validate) alarms indicated by another inspection system such as X-ray radiography. The technologies developed over the last two decades are now being implemented with good results. Further advances have been made over the last few years that increase the sensitivity, applicability and robustness of these systems. The advances range from the synchronous inspection of two sides of vehicles, increasing throughput and sensitivity and reducing imparted dose to the inspected object and its occupants (if any), to taking advantage of the neutron kinetic behavior of cargo to remove systematic errors, reducing background effects and improving fast neutron signals

  10. Advances in neutron based bulk explosive detection

    Science.gov (United States)

    Gozani, Tsahi; Strellis, Dan

    2007-08-01

    Neutron based explosive inspection systems can detect a wide variety of national security threats. The inspection is founded on the detection of characteristic gamma rays emitted as the result of neutron interactions with materials. Generally these are gamma rays resulting from thermal neutron capture and inelastic scattering reactions in most materials and fast and thermal neutron fission in fissile (e.g.235U and 239Pu) and fertile (e.g.238U) materials. Cars or trucks laden with explosives, drugs, chemical agents and hazardous materials can be detected. Cargo material classification via its main elements and nuclear materials detection can also be accomplished with such neutron based platforms, when appropriate neutron sources, gamma ray spectroscopy, neutron detectors and suitable decision algorithms are employed. Neutron based techniques can be used in a variety of scenarios and operational modes. They can be used as stand alones for complete scan of objects such as vehicles, or for spot-checks to clear (or validate) alarms indicated by another inspection system such as X-ray radiography. The technologies developed over the last two decades are now being implemented with good results. Further advances have been made over the last few years that increase the sensitivity, applicability and robustness of these systems. The advances range from the synchronous inspection of two sides of vehicles, increasing throughput and sensitivity and reducing imparted dose to the inspected object and its occupants (if any), to taking advantage of the neutron kinetic behavior of cargo to remove systematic errors, reducing background effects and improving fast neutron signals.

  11. DPZ-1M rhodium neutron detector performance

    International Nuclear Information System (INIS)

    The characteristics of the DPZ-1M rhodium self-powered neutron detector based on the calculational technique using corrected experimental data are given. These detectors are used for power distribution monitoring in the WWER reactors. For calculating neutron absorption in an emitter incident neutron flux is specified, while the probability of β-particles escape is determined on the base of empirical dependence of extrapolated electron path on its energy. In addition correction by the emither radius of the probability distribution of β-particles escape by experimental data is performed. The results obtained permit to conclude that the rhodium detector possesses high sensitivity to epithermal neutrons Which depends on the neutron spectrum form; current relation of burned-up and non burned- up detector seightly depends on the spectrum form, neutron gas temperature and average neutron spectral hardness

  12. Characterization of the Ljubljana TRIGA thermal column neutron radiographic facility

    International Nuclear Information System (INIS)

    An extensive characterization of the neutron beam of the existing neutron radiographic facility in the thermal column of the Ljubljana Triga Mark II research reactor is in progress. Neutron beam characteristics are needed to determine the effect of various neutron and gamma radiation on the neutron radiographic image. Commercially available medical scintillator converter screens based on Gd dioxy sulphite as well as Gd metal neutron converters are used to record neutron radiographic image. Thermal, epithermal and fast neutron fluxes were measured using Au and In activation detectors and cadmium ratio is determined. Neutron beam flux profiles are measured by film densitometry and by Au activation detector wires. By exposing films shielded by boral or lead plates individual contributions of thermal, epithermal neutrons and gamma radiation are estimated by densitometric measurements. By recording images of neutron image quality indicators BPI (Beam Purity Indicator) and SI (Sensitivity Indicator) produced by Riso, standard neutron radiography image characteristic are established. In gamma dosimetric measurements thermoluminescent detectors (CaF2Mn) are used. (author)

  13. Personnel neutron monitoring based on albedo technique

    International Nuclear Information System (INIS)

    This work deals with the study, design and test of a personal neutron monitor based on the detection of albedo neutrons from the body and its further relation to the incident flux. By this method, neutrons of energies below about 100 KeV can be efficiently detected, providing good information in the region where the biological effectiveness of neutron radiation starts to rise. The system consists of a pair of Thermoluminescent Detectors (6 LiF - 7 LiF) ∼ inside a polyethylene moderating body, in order to increase the sensitivity. The surface of the dosimeter facing away from the body is covered by a layer of a borated resin to assure appropriate shielding of incident low energy neutrons. The response of the dosimeter to monoenergetic neutrons from a 3 MeV Van de Graaff, to Am Be neutrons and to neutrons from a thermal column was investigated. The directional sensitivity, the effect of beam divergence was well as the effect of changes in dosimeter-to-body distances were also studied. (author)

  14. Compact Short-Pulsed Electron Linac Based Neutron Sources for Precise Nuclear Material Analysis

    Science.gov (United States)

    Uesaka, M.; Tagi, K.; Matsuyama, D.; Fujiwara, T.; Dobashi, K.; Yamamoto, M.; Harada, H.

    2015-10-01

    An X-band (11.424GHz) electron linac as a neutron source for nuclear data study for the melted fuel debris analysis and nuclear security in Fukushima is under development. Originally we developed the linac for Compton scattering X-ray source. Quantitative material analysis and forensics for nuclear security will start several years later after the safe settlement of the accident is established. For the purpose, we should now accumulate more precise nuclear data of U, Pu, etc., especially in epithermal (0.1-10 eV) neutrons. Therefore, we have decided to modify and install the linac in the core space of the experimental nuclear reactor "Yayoi" which is now under the decommission procedure. Due to the compactness of the X-band linac, an electron gun, accelerating tube and other components can be installed in a small space in the core. First we plan to perform the time-of-flight (TOF) transmission measurement for study of total cross sections of the nuclei for 0.1-10 eV energy neutrons. Therefore, if we adopt a TOF line of less than 10m, the o-pulse length of generated neutrons should be shorter than 100 ns. Electronenergy, o-pulse length, power, and neutron yield are ~30 MeV, 100 ns - 1 micros, ~0.4 kW, and ~1011 n/s (~103 n/cm2/s at samples), respectively. Optimization of the design of a neutron target (Ta, W, 238U), TOF line and neutron detector (Ce:LiCAF) of high sensitivity and fast response is underway. We are upgrading the electron gun and a buncher to realize higher current and beam power with a reasonable beam size in order to avoid damage of the neutron target. Although the neutron flux is limited in case of the X-band electron linac based source, we take advantage of its short pulse aspect and availability for nuclear data measurement with a short TOF system. First, we form a tentative configuration in the current experimental room for Compton scattering in 2014. Then, after the decommissioning has been finished, we move it to the "Yayoi" room and perform

  15. Notes on neutron flux measurement

    International Nuclear Information System (INIS)

    The main purpose of this work is to get an useful guide to carry out topical neutron flux measurements. Although the foil activation technique is used in the majority of the cases, other techniques, such as those based on fission chambers and self-powered neutron detectors, are also shown. Special interest is given to the description and application of corrections on the measurement of relative and absolute induced activities by several types of detectors (scintillators, G-M and gas proportional counters). The thermal arid epithermal neutron fluxes, as determined in this work, are conventional or effective (West cots fluxes), which are extensively used by the reactor experimentalists; however, we also give some expressions where they are related to the integrated neutron fluxes, which are used in neutron calculations. (Author) 16 refs

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

    OpenAIRE

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

    2013-01-01

    For the research of CCD neutron radiography, a neutron collimator was designed based on the exit of thermal neutron of the Boron Neutron Capture Therapy (BNCT) reactor. Based on the Geant4 simulations, the preliminary choice of the size of the collimator was determined. The materials were selected according to the literature data. Then, a collimator was constructed and tested on site. The results of experiment and simulation show that the thermal neutron flux at the end of theneutron collimat...

  17. Epithermal Inverse Kinetic Measurements and Their Interpretation Using a Two-Group Point-Kinetic Model

    International Nuclear Information System (INIS)

    Two of the methods that can be used for the measurement of the subcriticality of a multiplying system are the inverse kinetic (IK) and the pulsed neutron source (PNS) techniques. These methods depend considerably on correction factors and/or kinetic parameters, which usually need to be calculated using the same neutronic codes as those being validated via the experiments. The use of epithermal detectors to reduce the dependence of area-ratio PNS measurements on calculated correction factors was reported previously. In the current work, for the first time, epithermal detectors have been used for IK measurements. As in the case of the PNS experiments, these were carried out in core/reflector configurations with large spatial effects, systematic comparisons with thermal measurements clearly bringing out the considerably lower sensitivity of the epithermal IK results to calculational corrections. A new two-group point-kinetic model has currently been developed as an extension of the usual theoretical basis (employing a single energy group) for analyzing kinetic experiments. This has been essential for justifying the analysis methodology employed for the epithermal IK measurements

  18. A Tight Lattice, Epithermal Core Design for the Integral PWR

    International Nuclear Information System (INIS)

    An 8-year core design for an epithermal, water-cooled reactor has been developed based upon assessments of nuclear reactor physics, thermal-hydraulics and economics. An integral vessel configuration is adopted and self-supporting wire-wrap fuel is employed for the tight lattice of the epithermal core. A streaming path is incorporated in each assembly to ensure a negative void coefficient. A whole-core MCNP simulation of the tight core shows a negative void coefficient for any burnup with positive KEFF. The VIPRETM code has been used to calculate the critical heat flux (CHF) by means of an appropriate wire-wrap CHF correlation, specifically introduced in the source code. Economically, the high fuel enrichment (14% w/o 235U) and the very long core life (8 ys) lead to high lifetime-levelized unit fuel cycle cost (in mills/kWhre). However, both operation and maintenance and capital-related expenditures strongly benefited from the higher electric output per unit volume, which yielded quite small lifetime-levelized unit capital and operation and maintenance costs for the overall plant. Financing costs are included and an estimate is provided for the total lifetime-levelized unit cost of the epithermal core, which is about 20% lower than that of a more open lattice thermal spectrum core fitting into the same core envelope and with 4-year lifetime. (authors)

  19. Accelerator based steady state neutron source

    International Nuclear Information System (INIS)

    Using high current, cw linear accelerator technology, a spallation neutron source can achieve much higher average intensities than existing or proposed pulsed spallation sources. With about 100 mA of 300 MeV protons or deuterons, the accelerator based neutron research facility (ABNR) would initially achieve the 1016 n/cm2s thermal flux goal of the advanced steady state neutron source, and upgrading could provide higher steady state fluxes. The relatively low ion energy compared to other spallation sources has an important impact on R and D requirements as well as capital cost, for which a range of $300-450 M is estimated by comparison to other accelerator-based neutron source facilities. The source is similar to a reactor source is most respects. It has some higher energy neutrons but fewer gamma rays, and the moderator region is free of many of the design constraints of a reactor, which helps to implement sources for various neutron energy spectra, many beam tubes, etc., with the development of a multibeam concept and the basis for currents greater than 100 mA that is assumed in the R and D plan, the ABNR would serve many additional uses, such as fusion materials development, production of proton-rich isotopes, and other energy and defense program needs

  20. An accelerator based steady state neutron source

    International Nuclear Information System (INIS)

    Using high current, cw linear accelerator technology, a spallation neutron source can achieve much higher average intensities than existing or proposed pulsed spallation sources. With about 100 mA of 300 MeV protons or deuterons, the accelerator based neutron research facility (ABNR) would initially achieve the 1016 n/cm2 s themal flux goal of the advanced steady state neutron source, and upgrading could provide higher steady state fluxes. The relatively low ion energy compared to other spallation sources has an important impact on R and D requirements as well as capital cost, for which a range of Dollar 300-450 is estimated by comparison to other accelerator-based neutron source facilities. The source is similar to a reactor source in most respects. It has some higher energy neutrons but fewer gamma rays, and the moderator region is free of many of the design constraints of a reactor, which helps to implement sources for various neutron energy spectra, many beam tubes, etc. With the development of a multibeam concept and the basis for currents greater than 100 mA that is assumed in the R and D plan, the ABNR would serve many additional uses, such as fusion materials development, production of proton-rich isotopes, and other energy and defense program needs. (orig.)

  1. Design and Construct of In-Hospital Neutron Irradiator

    International Nuclear Information System (INIS)

    The In-hospital neutron irradiator (IHNI) is designed based on the design of the Miniature Neutron Source Reactor (MNSR) for boron neutron capture therapy (BNCT), NAA, physics experiments, training and teaching. The reactor of the IHNI with thermal power 30 kW is an undermoderated reactor of pool-tank type, UO2 with enrichment of 12.5% as fuel, light water as coolant and moderator, and metal beryllium as reflector. The fission heat produced by the reactor is removed by the natural circulation. On the both sides of the reactor core, there are two neutron beams, one is a thermal neutron beam, and the other, opposite to the thermal beam, is an epithermal neutron beam. An experimental thermal neutron beam is specially designed for the prompt gamma neutron activation analysis (PGNAA). In this paper, the design and experiment results of IHNI will be introduced. (author)

  2. Study of spectral response of a neutron filter. Design of a method to adjust spectra; Etude des moyens de conditionnement de la reponse spectrale d'un filtre a neutrons. Mise au point d'une methode d'ajustement rapide de spectre

    Energy Technology Data Exchange (ETDEWEB)

    Colomb-Dolci, F. [Universite Louis Pasteur, 67 - Strasbourg (France)

    1999-02-01

    The first part of this thesis describes an experimental method which intends to determine a neutron spectrum in the epithermal range [1 eV -10 keV]. Based on measurements of reaction rates provided by activation foils, it gives flux level in each energy range corresponding to each probe. This method can be used in any reactor location or in a neutron beam. It can determine scepter on eight energy groups, five groups in the epithermal range. The second part of this thesis presents a study of an epithermal neutron beam design, in the frame of Neutron Capture Therapy. A beam tube was specially built to test filters made up of different materials. Its geometry was designed to favour epithermal neutron crossing and to cut thermal and fast neutrons. A code scheme was validated to simulate the device response with a Monte Carlo code. Measurements were made at ISIS reactor and experimental spectra were compared to calculated ones. This validated code scheme was used to simulate different materials usable as shields in the tube. A study of these shields is presented at the end of this thesis. (author)

  3. Design of a medical reactor generating high quality neutron beams for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Boron neutron capture therapy (BNCT) is a binary treatment modality that can selectively irradiate tumor tissue. BNCT uses drugs containing a stable isotope of boron, B-10, that are capable of preferentially accumulating in the tumor, which is then irradiated with thermal neutrons. The interaction of the B-10 with a thermal neutron causes the B-10 nucleus to split, releasing an alpha particle and a lithium nucleus. These products of the boron neutron capture reaction are very damaging to cells but have a path length in tissue of approximately 14 micrometers, or roughly the diameter of one or two cells. Thus, most of the ionizing energy imparted to tissue is localized to B-10-loaded cells. Since the early 1980s, there have been considerable improvements in boron compounds and neutron beams. More is known now about the radiation biology of BNCT, which has reemerged as a potentially useful method for preferential irradiation of tumors. Clinical trials have been initiated at BNL and MIT, with an improved boron compound and epithermal neutrons. At this time, nuclear reactors are the only demonstrated satisfactory sources of epithermal neutrons. While some reactors are available and within reach of cancer treatment centers, a question arises as to the feasibility and practicality of placing new epithermal neutron sources in hospitals. In this thesis, we design a square reactor (that can easily be reconfigured into polygonal reactors as the need arises) with four slab type assemblies to produce two epithermal neutron beams and two thermal neutron beams for use in neutron capture therapy. This square reactor with four large-area faces consists of 1056 U3Si-Al fuel elements and 36 B4C control rods. The proposed facility, based on this square reactor core with a maximum operating power of 300kW, provides an epithermal neutron beam of 3.2x109 nepi/cm2 · s intensity with low contamination by fast neutrons (<1.6x10-13 Gy · cm2/nepi) and gamma rays (<1.0x10-13 Gy · cm2/nepi

  4. Test of 3He-based neutron polarizers at NIST

    International Nuclear Information System (INIS)

    Neutron spin filters based on polarized 3He are useful over a wide neutron energy range and have a large angular acceptance among other advantages. Two optical pumping methods, spin-exchange and metastability-exchange, can produce the volume of highly polarized 3He gas required for such neutron spin filters. We report a test of polarizers based on each of these two methods on a new cold, monochromatic neutron beam line at the NIST Center for Neutron Research

  5. Final design and construction issues of the TAPIRO epithermal column

    International Nuclear Information System (INIS)

    The construction of the epithermal column for clinical trials at the 5 kW fast reactor TAPIRO (ENEA, Casaccia, Italy) has been completed, the experimental bunker in the reactor hall has been designed and the beam characterisation will shortly be underway. As has been reviewed at the last two ICNCT conferences, the low power of the neuron source and the relatively distant patient position outside the reactor shield led to a column design with certain characteristics. One consequence is the employment of a collimator containing lead of high purity with the resultant problems of mechanical construction. Another is the substantial neutron leakage from the column outside the aperture into the experimental bunker. Furthermore the absence of a gamma shield has led to an electron dose to the skin. This is resolved with an electron shield of aluminium. Here the construction and final design issues are discussed and the state of the project is presented. (author)

  6. Microdosimetry for Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    The specific aims of the research proposal were as follows: (1) To design and construct small volume tissue equivalent proportional counters for the dosimetry and microdosimetry of high intensity thermal and epithermal neutron beams used in BNCT, and of modified fast neutron beams designed for boron neutron capture enhanced fast neutron therapy (BNCEFNT). (2) To develop analytical methods for estimating the biological effectiveness of the absorbed dose in BNCT and BNCEFNT based on the measured microdosimetric spectra. (3) To develop an analytical framework for comparing the biological effectiveness of different epithermal neutron beams used in BNCT and BNCEFNT, based on correlated sets of measured microdosimetric spectra and radiobiological data. Specific aims (1) and (2) were achieved in their entirety and are comprehensively documented in Jay Burmeister's Ph.D. dissertation entitled ''Specification of physical and biologically effective absorbed dose in radiation therapies utilizing the boron neutron capture reaction'' (Wayne State University, 1999). Specific aim (3) proved difficult to accomplish because of a lack of sufficient radiobiological data

  7. Development of a new electronic neutron imaging system

    CERN Document Server

    Brenizer, J S; Gibbs, K M; Mengers, P; Stebbings, C T; Polansky, D; Rogerson, D J

    1999-01-01

    An electronic neutron imaging camera system was developed for use with thermal, epithermal, and fast neutrons in applications that include nondestructive inspection of explosives, corrosion, turbine blades, electronics, low Z components, etc. The neutron images are expected to provide information to supplement that available from X-ray tests. The primary camera image area was a 30x30 cm field-of-view with a spatial resolution approaching 1.6 line pairs/mm (lp/mm). The camera had a remotely changeable second lens to limit the field-of-view to 7.6x7.6 cm for high spatial resolution (at least 4 lp/mm) thermal neutron imaging, but neutron and light scatter will limit resolution for fast neutrons to about 0.5 lp/mm. Remote focus capability enhanced camera set-up for optimum operation. The 75 dB dynamic range camera system included sup 6 Li-based screens for imaging of thermal and epithermal neutrons and ZnS(Ag)-based screens for fast neutron imaging. The fast optics was input to a Super S-25 Gen II image intensifi...

  8. An epithermal irradiation terminal project for the IPR-R1 Triga Mark I reactor, CDTN/CNEN

    International Nuclear Information System (INIS)

    The IPR-R1 Triga Mark I is a research reactor operating since 1960. It has being used mainly for training neutron activation analysis and production of some special radioisotopes. In the last years, it is coming up the necessity of using a thermal neutrons filter during neutron activation. It is in order to solve many specific situations where only activation by fast and epithermal neutrons is required. For instance, the labeling of some special molecules used for pharmaceutical investigations and the activation of biological samples in which thermal sodium activation may cause undesired analysis interferences. The usual procedure used in such cases - to irradiate the samples in the rotary specimen rack inside a cadmium box with a 1 mm wall thickness - normally offers radiological risks due to the high exposure dose. The aim of the project presented here is to optimize the procedures when the epithermal irradiation is needed. (author)

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

    International Nuclear Information System (INIS)

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

  10. Accelerator-based neutron source for the neutron-capture and fast neutron therapy at hospital

    Science.gov (United States)

    Bayanov, B. F.; Belov, V. P.; Bender, E. D.; Bokhovko, M. V.; Dimov, G. I.; Kononov, V. N.; Kononov, O. E.; Kuksanov, N. K.; Palchikov, V. E.; Pivovarov, V. A.; Salimov, R. A.; Silvestrov, G. I.; Skrinsky, A. N.; Soloviov, N. A.; Taskaev, S. Yu.

    The proton accelerator complex for neutron production in lithium target discussed, which can operate in two modes. The first provides a neutron beam kinematically collimated with good forward direction in 25° and average energy of 30 keV, directly applicable for neutron-capture therapy with high efficiency of proton beam use. The proton energy in this mode is 1.883-1.890 MeV that is near the threshold of the 7Li( p, n) 7Be reaction. In the second mode, at proton energy of 2.5 MeV, the complex-produced neutron beam with maximum energy board of 790 keV which can be used directly for fast neutron therapy and for neutron-capture therapy after moderation. The project of such a neutron source is based on the 2.5 MeV original electrostatic accelerator tandem with vacuum insulation developed at BINP which is supplied with a high-voltage rectifier. The rectifier is produced in BINP as a part of ELV-type industrial accelerator. Design features of the tandem determining its high reliability in operation with a high-current (up to 40 mA) H - ion beam are discussed. They are: the absence of ceramic accelerator columns around the beam passage region, good conditions for pumping out of charge-exchange gaseous target region, strong focusing optics and high acceleration rate minimizing the space charge effects. The possibility of stabilization of protons energy with an accuracy level of 0.1% necessary for operation in the near threshold region is considered. The design description of H - continuous ion source with a current of 40 mA is also performed. To operate with a 100 kW proton beam it is proposed to use liquid-lithium targets. A thin lithium layer on the surface of a tungsten disk cooled intensively by a liquid metal heat carrier is proposed for use in case of the vertical beam, and a flat liquid lithium jet flowing through the narrow nozzle - for the horizontal beam.

  11. Material identification based upon energy-dependent attenuation of neutrons

    Science.gov (United States)

    Marleau, Peter

    2015-10-06

    Various technologies pertaining to identifying a material in a sample and imaging the sample are described herein. The material is identified by computing energy-dependent attenuation of neutrons that is caused by presence of the sample in travel paths of the neutrons. A mono-energetic neutron generator emits the neutron, which is downscattered in energy by a first detector unit. The neutron exits the first detector unit and is detected by a second detector unit subsequent to passing through the sample. Energy-dependent attenuation of neutrons passing through the sample is computed based upon a computed energy of the neutron, wherein such energy can be computed based upon 1) known positions of the neutron generator, the first detector unit, and the second detector unit; or 2) computed time of flight of neutrons between the first detector unit and the second detector unit.

  12. Development of a new electronic neutron imaging system

    International Nuclear Information System (INIS)

    An electronic neutron imaging camera system was developed for use with thermal, epithermal, and fast neutrons in applications that include nondestructive inspection of explosives, corrosion, turbine blades, electronics, low Z components, etc. The neutron images are expected to provide information to supplement that available from X-ray tests. The primary camera image area was a 30x30 cm field-of-view with a spatial resolution approaching 1.6 line pairs/mm (lp/mm). The camera had a remotely changeable second lens to limit the field-of-view to 7.6x7.6 cm for high spatial resolution (at least 4 lp/mm) thermal neutron imaging, but neutron and light scatter will limit resolution for fast neutrons to about 0.5 lp/mm. Remote focus capability enhanced camera set-up for optimum operation. The 75 dB dynamic range camera system included 6Li-based screens for imaging of thermal and epithermal neutrons and ZnS(Ag)-based screens for fast neutron imaging. The fast optics was input to a Super S-25 Gen II image intensifier, fiber optically coupled to a 1134 (h)x486 (v) frame transfer CCD camera. The camera system was designed to be compatible with a Navy-sponsored accelerator neutron source. The planned neutron source is an RF quadrupole accelerator that will provide a fast neutron flux of 107 n/cm2-s (at a source distance of 1 m) at an energy of about 2.2 MeV and a thermal neutron flux of 106 n/cm2-s at a source L/D ratio of 30. The electronic camera produced good quality real-time images at these neutron levels. On-chip integration could be used to improve image quality for low flux situations. The camera and accelerator combination provided a useful non-reactor neutron inspection system

  13. Development of fast neutron radiography system based on portable neutron generator

    Science.gov (United States)

    Yi, Chia Jia; Nilsuwankosit, Sunchai

    2016-01-01

    Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

  14. Development of fast neutron radiography system based on portable neutron generator

    International Nuclear Information System (INIS)

    Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons

  15. Thermal neutron analysis (TNA) explosive detection based on electronic neutron generators

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.C. [Science Applications Int. Corp., Santa Clara, CA (United States); Mahood, D.B. [Science Applications Int. Corp., Santa Clara, CA (United States); Ryge, P. [Science Applications Int. Corp., Santa Clara, CA (United States); Shea, P. [Science Applications Int. Corp., Santa Clara, CA (United States); Gozani, T. [Science Applications Int. Corp., Santa Clara, CA (United States)

    1995-05-01

    Thermal neutron analysis explosive detection systems have been developed and demonstrated for inspection of checked airline baggage and for detection of buried land mines. Thermal neutrons from a moderated neutron source impinge on the inspected object, and the resulting capture gamma ray signatures provide detection information. Isotopic neutron sources, e.g. {sup 252}Cf, are compact, economical and reliable, but they are subject to the licensing requirements, safety concerns and public perception problems associated with radioactive material. These are mitigated by use of an electronic neutron generator - an ion accelerator with a target producing neutrons by a nuclear reaction such as D(d, n){sup 3}He or {sup 9}Be(d, n){sup 10}B. With suitable moderator designs based on neutron transport codes, operational explosive detection systems can be built and would provide effective alternatives to radioactive neutron sources. Calculations as well as laboratory and field experience with three generator types will be presented. (orig.).

  16. Thermal neutron analysis (TNA) explosive detection based on electronic neutron generators

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.; Mahood, D.B.; Ryge, P. [Science Applications International Corp., Santa Clara, CA (United States)] [and others

    1994-12-31

    Thermal neutron analysis explosive detection systems have been developed and demonstrated for inspection of checked airline baggage and for detection of buried land mines. Thermal neutrons from a moderated neutron source impinge on the inspected object and the resulting capture gamma ray signatures provide detection information. Isotopic neutron sources, e.g. {sup 252}Cf, are compact, economical and reliable, but they are subject to the licensing requirements, safety concerns and public perception problems associated with radioactive material. These are mitigated by use of an electronic neutron generator - an ion accelerator with a target producing neutrons by a nuclear reaction such as D(d,n){sup 3}He or {sup 9}Be(d,n){sup 10}B. With suitable moderator designs based on neutron transport codes, operational explosive detection systems can be build and would provide effective alternatives to radioactive neutron sources. Calculations as well as laboratory and field experience with three generator types will be presented.

  17. Development of fast neutron radiography system based on portable neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Chia Jia, E-mail: gei-i-kani@hotmail.com; Nilsuwankosit, Sunchai, E-mail: sunchai.n@chula.ac.th [Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Phayathai Rd., Patumwan, Bangkok, THAILAND 10330 (Thailand)

    2016-01-22

    Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

  18. The Argonne ACWL, a potential accelerator-based neutron source for BNCT

    International Nuclear Information System (INIS)

    THE CWDD (Continuous Wave Deuterium Demonstrator) accelerator was designed to accelerate 80 mA cw of D- to 7.5 MeV. Most of the hardware for the first 2 MeV was installed at Argonne and major subsystems had been commissioned when program funding from the Ballistic Missile Defense Organization ended in October 1993. Renamed the Argonne Continuous Wave Linac (ACWL), we are proposing to complete it to accelerate either deuterons to 2 MeV or protons to 3-3.5 MeV. Equipped with a beryllium or other light-element target, it would make a potent source of neutrons (on the order of 1013 n/s) for BNCT and/or neutron radiography. Project status and proposals for turning ACWL into a neutron source are reviewed, including the results of a computational study that was carried out to design a target/moderator to produce an epithermal neutron beam for BNCT. (orig.)

  19. Geological Characteristics of Epithermal Ore Concentrated Areas and Epithermal Ore Deposits in China

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The epithermal ore concentrated area is located in Southwestern China. We systematically study the regional geological characteristics such as the basement of Proterozoic, the capping bed, Moho, geothermal feature and tectonics, and discuss the relationship between distributed characteristics of the epithermal ore deposits and ore-control factors in this paper. It is concluded that the conditions, under which the epithermal ore deposits form, are huge thick basement of Proterozoic, long-time and wide-scope developed capping bed and weak magmatic activity. The basement of Proterozoic that enriches volcanic matters and carbon and the carbonaceous-bearing and paleo-pool-bearing capping bed provides main ore source. The large and deep faults and paleopool accordance with gravity anomaly gradient control the distribution of epithermal ore deposits. The lithologic assembles of microclastic rocks and carbonate rocks in the capping bed provide spaces of ore precipitation and create conditions of ore precipitation. The coincidence of many geological factors above forms the epithermal ore concentrated area.

  20. New neutron detector based on Micromegas technology for ADS projects

    CERN Document Server

    Andriamonje, Samuel A; Aune, Stephan; Ban, Gilles; Breaud, Stephane; Blandin, Christophe; Ferrer, Esther; Geslot, Benoit; Giganon, Arnaud; Giomataris, Ioannis; Jammes, Christian; Kadi, Yacine; Laborie, Philippe; Lecolley, Jean Francois; Pancin, Julien; Riallot, Marc; Rosa, Roberto; Sarchiapone, Lucia; Steckmeyer, Jean Claude; Tillier, Joel

    2006-01-01

    A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. The advantage of this detector compared to conventional neutron flux detectors and the results obtained with the first prototype at the CELINA 14 MeV neutron source facility at CEA-Cadarache are presented. The future developments of operational Piccolo-Micromegas for fast neutron reactors are also described.

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

    CERN Document Server

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

    2013-01-01

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

  2. Capture-gated neutron spectrometry

    CERN Document Server

    Czirr, J B; Buehler, D; McKnight, T K; Carroll, J L; Abbott, T; Wilcox, E

    2002-01-01

    The applications of a new inorganic scintillator, lithium gadolinium borate, to neutron dosimetry and spectroscopy, are described. A dosimeter using this material registers, in separate energy bins, thermal, epithermal and MeV neutrons. A spectrometer for MeV neutrons has a calculated energy resolution of 10% FWHM.

  3. New neutron detector based on Micromegas technology for ADS projects

    OpenAIRE

    Andriamonje, Samuel; Andriamonje, Gregory; Aune, Stephan; Ban, Gilles; Breaud, Stephane; Blandin, Christophe; Ferrer, Esther; Geslot, Benoit; Giganon, Arnaud; Giomataris, Ioannis; Jammes, Christian; Kadi, Yacine; Laborie, Philippe; Lecolley, Jean Francois; Pancin, Julien

    2006-01-01

    A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. The advantage of this detector compared to conventional neutron flux detectors and the results obtained with the first prototype at the CE...

  4. Determination of hydrogen content by neutron techniques

    International Nuclear Information System (INIS)

    The commonly available techniques for the determination of hydrogen dissolved in solids are usually destructive from the point of view of the sample. A new, nondestructive method for this kind of measurements has been developed at our laboratory, with the requirement of improved sensitivity for massive samples. This scattering method is based on the use of epithermal neutrons, and has been implemented through the design and construction of a spectrometer dedicated to that task. In addition, the traditional transmission method has been employed to determine hydrogen content in metals, using the full sub thermal and thermal neutron energy ranges. A pulsed neutron source based on an electron LINAC is employed, together with time-of-flight techniques. In this work we will present some results illustrative of the sensitivity achieved by these neutron techniques in different systems and for a wide range of hydrogen concentrations. (author)

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

    Science.gov (United States)

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

    2015-12-01

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

  6. Integrated photomultiplier tube base for neutron array

    International Nuclear Information System (INIS)

    National Array of Neutron Detector (NAND) at IUAC is planned to have 100 numbers of liquid scintillator BC501A cells of 5'' X 5'' size coupled to a 130 mm Photomultiplier tube (PMT). Each PMT requires a dedicated set of front end electronics such as voltage divider network, high voltage power supply, charge sensitive pre-amplifier for dynode signal. Due to large number of these detectors and scarcity of space, it is proposed to have these electronics integrated with detector along with remote control and status read back. Three prototype integrated PMT bases have been designed, tested and implemented recently during an experiment with linac beam

  7. Experimental Study on Neutron Radiography Device Based on Reactor

    Institute of Scientific and Technical Information of China (English)

    LU; Jin; PENG; Dan; HAO; Qian; YU; Bo-xiang; LI; Yi-guo

    2012-01-01

    <正>Neutron radiography is a non-destructive testing developing fast recently, which requires stable and proper neutron source with low γ background. Neutrons from In-hospital Neutron Irradiator (IHNI) could meet this requirement. Based on the neutron beams of IHNI, a collimator is designed and built for neutron radiography. The experiment results show that in the case of IHNI working at normal rated power, the neutron flux at the end of the collimator is 1.43×106 cm-2·s-1; The max collimation ratio (L/D) is 58; the γ dose rate is 6.3×106 mSv/s. In a word, the collimator could be used for neutron radiography.

  8. Grazing-Incidence Neutron Optics based on Wolter Geometries

    Science.gov (United States)

    Gubarev, M. V.; Ramsey, B. D.; Mildner, D. F. R.

    2008-01-01

    The feasibility of grazing-incidence neutron imaging optics based on the Wolter geometries have been successfully demonstrated. Biological microscopy, neutron radiography, medical imaging, neutron crystallography and boron neutron capture therapy would benefit from high resolution focusing neutron optics. Two bounce optics can also be used to focus neutrons in SANS experiments. Here, the use of the optics would result in lower values of obtainable scattering angles. The high efficiency of the optics permits a decrease in the minimum scattering vector without lowering the neutron intensity on sample. In this application, a significant advantage of the reflective optics over refractive optics is that the focus is independent of wavelength, so that the technique can be applied to polychromatic beams at pulsed neutron sources.

  9. Scattered Neutron Tomography Based on A Neutron Transport Inverse Problem

    Energy Technology Data Exchange (ETDEWEB)

    William Charlton

    2007-07-01

    Neutron radiography and computed tomography are commonly used techniques to non-destructively examine materials. Tomography refers to the cross-sectional imaging of an object from either transmission or reflection data collected by illuminating the object from many different directions.

  10. Neutron activation analysis for development of mercury sorbent based on blue-green alga salipriina palatinates

    International Nuclear Information System (INIS)

    Epithermal neutron activation analysis was used to study interaction of blue-green alga Spirulina platensis with toxic metal mercury. Various concentrations of Hg(II) were added to cell cultures in a nutrient medium. The dynamic of accumulation of Hg was investigated over days in relation to Spirulina biomass growth. The process of Hg adsorption by Spirulina biomass was studied in short-time experiments. The isotherm of adsorption was / out in Freindlich coordinates. Natural Spirulina biomass has potential to be used in the remediation of sewage waters at Hg concentrations ∼ 100 μg/1

  11. Comparison of depth-dose distributions between reactor and accelerator neutron beams proposed by design studies

    International Nuclear Information System (INIS)

    Accelerator epithermal neutron beams produced by 7Li(p,n)7Be reactions were compared with reactor neutron beams using a fission converter (20% enriched 235U 5mm-thick plate) from view points of neutron spectrum and depth-dose distributions in a phantom. It is possible to design accelerator epithermal neutron beams having better depth-dose distributions than reactor neutron beams. (author)

  12. Design of a mobile neutron radiography installation based on a compact sealed tube neutron generator

    International Nuclear Information System (INIS)

    A series of optimum conditions are taken into account in the construction of neutron radiography (NR) installation based on a sealed tube neutron generator capable of generating 1010 n/s with 14 MeV. The characteristics of NNU screens, a kind of self-made 6LiF·ZnS(Ag) scintillation intensifying screen are presented. Finally, some neutron radiographers taken by this NR installation and NNU screens are given

  13. Design of a mobile neutron radiography installation based on a compact sealed tube neutron generator

    Institute of Scientific and Technical Information of China (English)

    MaWei-Chao; YaoAn-Ju; 等

    1997-01-01

    A series of optimum conditions are taken into account in the construction of neutron radiography(NR) installation based on a sealed tube neutron generator capable of gnerating 1010 n/s with 14MeV.The characteristics of NNU screens,a kind of self-made 6LiF.ZnS(Ag)scintillation intensifying screen are presented.Finally,some neutron radiographies taken by this NR installation and NNU screens are given.

  14. Analysis of Libyan Arable soils by means of Thermal and Epithermal Naca

    International Nuclear Information System (INIS)

    Fertilizers and agrochemicals play a very important role in increasing the land productivity and fertility. Fertilizers contain the world nutrients N, P2O5 and K2O. Environmental problems connected with phosphate fertilizers are eutrophication and the buildup of heavy metals (radioactive and toxic elements). The human metabolism is based on an enzyme system making use of the essential elements (Fe, Mn, Zn, Cu---) while eliminatig the harmful ones (As, Be, Cd, Hg, Pb--). We investigated Libyan arable soils from many regions used mainly for cereals production, by nuclear and related techniques, such as INAA, ED-XRF, ICP-OES, ----etc. The aim of present paper is to determine the level of some minor and trace elements (As, Au, Br, Cd, Ga, Gd, Ho, K, La Mo, Na, Sb, Sm and U) by thermal and epithermal NAA in selected Libyan arable soils. Soil samples were collected from Makkonsa and Wadi Arial projects, South Libya. Sets of samples, standards and flux monitors were irradiated both in TNNA and ENNA methods in different positions in the reactor at Tajura Nuclear Research Center. Gamma ray spectrometry of the irradiated samples was carried out with a 27%relative efficiency HP-Ge detector with a resolution of 1.9 ke V at 1332.5 ke V; using a PC-based ACCUSPEC 8000-channel analyzer for the registration of y-spectra. It was concluded that the determination of trace elements in soil is important; it can provide information about the environment in which the plants are grown and about the way by which the trace elements are carried to man through the chain soil--plant--animal--man. Epithermal neutron activation is a useful technique for reducing the major activity from the matrix in the soil samples, and analytical sensitivities are significantly improved for many elements for medium-lived radionuclides. The determination of primary nutrients, potassium and micronutrients molybdenum in these selected soils are very important for the management of fertilizers in these projects

  15. Pulsed neutron generator for logging

    International Nuclear Information System (INIS)

    A pulsed neutron generator for uranium logging is described. This generator is one component of a prototype uranium logging probe which is being developed by SLA to detect, and assay, uranium by borehole logging. The logging method is based on the measurement of epithermal neutrons resulting from the prompt fissioning of uranium from a pulsed source of 17.6 MeV neutrons. An objective of the prototype probe was that its diameter not exceed 2.75 inches, which would allow its use in conventional rotary drill holes of 4.75-inch diameter. This restriction limited the generator to a maximum 2.375-inch diameter. The performance requirements for the neutron generator specified that it operate with a nominal output of 5 x 106 neutrons/pulse at up to 100 pulses/second for a one-hour period. The development of a neutron generator meeting the preliminary design goals was completed and two prototype models were delivered to SLA. These two generators have been used by SLA to log a number of boreholes in field evaluation of the probe. The results of the field evaluations have led to the recommendation of several changes to improve the probe's operation. Some of these changes will require additional development effort on the neutron generator. It is expected that this work will be performed during 1977. The design and operation of the first prototype neutron generators is described

  16. Modelling collimator of radial beam port Kartini reactor for boron neutron capture therapy

    International Nuclear Information System (INIS)

    One of the cancer therapy methods is BNCT (Boron Neutron Capture Therapy). BNCT utilizes neutron nature by 10B deposited on cancer cells. The superiority of BNCT compared to the radiation therapy is the high level of selectivity since its level is within cell. This study was carried out on collimator modelling in radial beam port of reactor Kartini for BNCT. The modelling was conducted by simulation using software of Monte Carlo N-Particle version 5 (MCNP 5). MCNP5 is a package of the programs for both simulating and calculating the problem of particle transport by following the life cycle of a neutron since its birth from fission reaction, transport on materials, until eventually lost due to the absorption reaction or out from the system. The collimator modelling used materials which varied in size in order to generate the value of each of the parameters in accordance with the recommendation of the IAEA, the epithermal neutron flux (ϕepi) > 1.0 x 109n.cm-2s-1, the ratio between the neutron dose rate fast and epithermal neutron flux (Df/ϕepi) < 2.0 x 10-13 Gy.cm2.n-1, the ratio of gamma dose rate and epithermal neutron flux (Dγ/ϕepi) < 2.0 X10-13 Gy.cm2.n-1, the ratio between the thermal and epithermal neutron flux (ϕTh/ϕepi)< 0.05 and the ratio between the current and flux of the epithermal neutron (J/ϕepi) > 0.7. Based on the results of the optimization of the modeling, the materials and sizes of the collimator construction obtained were 0.75 cm Ni as collimator wall, 22 cm Al as a moderator and 4.5 cm Bi as a gamma shield. The outputs of the radiation beam generated from collimator modeling of the radial beam port were ϕepi = 5.25 x 106 n.cm-2.s-1, Df/ϕepi = 1.17 x 10-13Gy.cm2.n-1, Dγ/ϕepi = 1.70 x 10-12 Gy.cm2.n-1, ϕTh/ϕepi = 1.51 and J/ϕepi = 0.731. Based on this study, the result of the beam radiation coming out of the radial beam port dis not fully meet the criteria recommended by IAEA so need to continue this study to get the criteria of IAEA

  17. The first main steps for development of BNCT neutron sources at the Ukrainian and Uzbek Research Reactors

    International Nuclear Information System (INIS)

    Both in Ukraine and in Uzbekistan, epithermal neutron irradiation facilities for Boron Neutron Capture Therapy (BNCT) are under consideration, as the need for them is very large. Based on information from medical cancer treatment institutions of the total number of patients identified with cancer, about 5000 have brain tumours. The most prospective method of their treatment is BNCT. Both in Ukraine and in Uzbekistan, this method can be implemented on existing research reactors. Modification of research reactors may be a relatively straightforward and inexpensive way to develop a BNCT neutron source, especially in comparison with construction of new reactors specialized for BNCT. However, prior to any reactor modification, careful calculations need to be performed, which take into account all the peculiarities of the specific reactor system. Based on the world experience in epithermal neutron beam development, it is very clear that the research reactors in Kyiv (Kyiv Research Reactor-KRR) and Tashkent (Tashkent Research Reactor-TRR) may be reconstructed into epithermal irradiation facilities. Selection of the most suitable materials for moderator, collimator, shielding, etc., demands carrying out calculations considering their individual characteristics. Since the KRR and TRR are the same kind of research reactors, with for example similar thermal columns, the development of a BNCT neutron source at these research reactors may be achieved in a like manner. The development plan and the first experience in this direction (using preliminary MCNP calculation results) are presented here. (author)

  18. Neutron elastic scattering cross-sections measurement on carbon and fluorine in epithermal energy range using PEREN platform; Mesure des sections efficaces de diffusion elastique des neutrons sur le carbone et le fluor dans le domaine epithermique sur la plate-forme PEREN

    Energy Technology Data Exchange (ETDEWEB)

    Thiolliere, N

    2005-10-15

    Molten Salt Reactor (MSR) based on Th/U cycle is one of the new generation concepts for nuclear energy production. A typical MSR is a graphite-moderated core with liquid fuel ({sup 7}LiF +ThF{sub 4} + UF{sub 4}). Many numerical studies based on Monte-Carlo codes are currently carried out but the validity of these numerical result relies on the precise knowledge of neutron cross sections used such as elastic scattering on carbon ({sigma}{sub C}), fluorine ({sigma}{sub F}) and lithium 7 ({sigma}{sub Li}). The goal of this work is to obtain {sigma}{sub C} and {sigma}{sub F} between 1 eV and 100 keV. Such measurements have been performed at the Laboratoire de Physique Subatomique et de Cosmologie (LPSC) de Grenoble on the experimental platform PEREN using slowing-down time spectrometers (C and CF{sub 2}) associated to a pulsed neutron generator (GENEPI). Capture rates are obtained for reference materials (Au, Ag, Mo and In) using YAP scintillator coupled to a photo-multiplier. Very precise simulations (MCNP code) of the experimental setup have been performed and comparison with experiments has led to the determination of {sigma}{sub C} and {sigma}{sub F} with accuracies of 1% and 2% respectively. These results show a small discrepancy to evaluated nuclear data file (ENDF). Measures of total cross-sections {sigma}{sub C} and {sigma}{sub F} at higher energy (200 - 600 keV) were also carried out at Centre des Etudes Nucleaires de Bordeaux using a transmission method. Mono-energetic neutrons were produced by protons accelerated by a Van de Graaff accelerator on a LiF target and transmitted neutrons are counted in a proportional hydrogen gaseous detector. Discrepancies of 5% and 9% for {sigma}{sub C} and {sigma}{sub F} respectively with ENDF have been shown. (author)

  19. A neutron beam polarizer for study of parity violation in neutron-nucleus interactions

    International Nuclear Information System (INIS)

    A dynamically-polarized proton target operating at 5 Tesla and 1 K has been built to, neutron beam for studies of parity violation in compound-nuclear resonances. Nearly 0.9 proton polarization was obtained in an electron-beam irradiated ammonia target. This was used to produce a neutron beam polarization of 0.7 at epithermal energies. The combination of the polarized proton target and the LANSCE spallation neutron source produces the most intense pulsed polarized epithermal neutron beam in the world. The neutron-beam polarizer is described and methods to determine neutron beam polarization are presented

  20. Transmission and Reflection of Neutrons Using Foil Activation Technique

    International Nuclear Information System (INIS)

    A new neutron irradiation facility has been designed, constructed .and located at the Experimental Nuclear Physics Department, NRC, AEA, cairo. The neutrons were obtained from CNIF2 (Second Cairo Neutron Irradiation Facility) that is based on one 241 Am-Be(α, n) isotopic neutron source with a present activity of about 175 GBq results in a neutron yield of about 1.04 x107 n/s. The geometrical arrangements of the facility consider the safety and protection rules aspects. MCNP5 code is used to estimate radiation doses and neutron fluxes. This new irradiation facility provides fast and epithermal neutrons that can be used in basic research and industrial applications. The aim of the present work is to study the characteristics of this new irradiation facility and to develop methods able to use fast and epithermal neutron in some different applications. Experimental measurements for the transmission and reflection of neutrons were carried out via a number of hydrogenous materials using the activation foil technique. A comparison of the experimental results with that calculated by using Monte Carlo simulation method is presented Using the neutron transmission technique in combination with foil activation method, our arrangement is used to measure the total neutron microscopic cross-sections for some compounds. The facility is calibrated and suitable to estimate the hydrogen content H (wt %) and the weight ratios C/H in hydrocarbon materials and was used to measure these ratios for some Egyptian crude oil samples. A brief overview of the neutron activation analysis methods for elemental concentrations in bulk samples in natural conditions is presented.

  1. BINP pilot accelerator-based neutron source for neutron capture therapy

    International Nuclear Information System (INIS)

    Neutron source based on accelerator has been proposed for neutron capture therapy at hospital. Innovative approach is based upon tandem accelerator with vacuum insulation and near threshold 7Li(p,n)7Be neutron generation. Pilot innovative accelerator based neutron source is under going to start operating now at BINP, Novosibirsk. Negative ion source with Penning geometry of electrodes has been manufactured and dc H- ion beam has been obtained. Study of beam transport was carried out using prototype of tandem accelerator. Tandem accelerator and ion optical channels have been manufactured and assembled. Neutron producing target has been manufactured, thermal regimes of target were studied, and lithium evaporation on target substrate was realized. In the report, the pilot facility design is given and design features of facility components are discussed. Current status of project realization, results of experiments and simulations are presented. (author)

  2. Improved Fission Neutron Data Base for Active Interrogation of Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Pozzi, Sara; Czirr, J. Bart; Haight, Robert; Kovash, Michael; Tsvetkov, Pavel

    2013-11-06

    This project will develop an innovative neutron detection system for active interrogation measurements. Many active interrogation methods to detect fissionable material are based on the detection of neutrons from fission induced by fast neutrons or high-energy gamma rays. The energy spectrum of the fission neutrons provides data to identify the fissionable isotopes and materials such as shielding between the fissionable material and the detector. The proposed path for the project is as follows. First, the team will develop new neutron detection systems and algorithms by Monte Carlo simulations and bench-top experiments. Next, They will characterize and calibrate detection systems both with monoenergetic and white neutron sources. Finally, high-fidelity measurements of neutron emission from fissions induced by fast neutrons will be performed. Several existing fission chambers containing U-235, Pu-239, U-238, or Th-232 will be used to measure the neutron-induced fission neutron emission spectra. The challenge for making confident measurements is the detection of neutrons in the energy ranges of 0.01 – 1 MeV and above 8 MeV, regions where the basic data on the neutron energy spectrum emitted from fission is least well known. In addition, improvements in the specificity of neutron detectors are required throughout the complete energy range: they must be able to clearly distinguish neutrons from other radiations, in particular gamma rays and cosmic rays. The team believes that all of these challenges can be addressed successfully with emerging technologies under development by this collaboration. In particular, the collaboration will address the area of fission neutron emission spectra for isotopes of interest in the advanced fuel cycle initiative (AFCI).

  3. Chemical composition of the lunar surface from neutron leakage fluxes

    International Nuclear Information System (INIS)

    The neutron leakage fluxes from the lunar surface are calculated by Monte Carlo transport code based on Geant4. The integral fluxes of fast neutrons, epi-thermal neutrons and thermal neutrons are analyzed. Numerical results for 20 kinds of lunar soils and 7 minerals show that the fast neutron fluxes are linearly related to the average atomic mass numbers of the lunar materials used in simulations. Meanwhile, the average atomic mass numbers are strongly modulated by the abundances of iron (Fe) and titanium (Ti), and a linear relationship between the average atomic mass numbers and the abundances of Fe and Ti is found. Furthermore, the results show that the ratios of epi-thermal to thermal fluxes for lunar soils are linearly related to the macroscopic absorption cross sections of lunar materials, and that the macroscopic absorption cross sections monotonically increase with the abundances of Fe and Ti by a simple function. Then we reach the conclusion that the neutron fluxes can provide the information about the Fe and Ti contents. (authors)

  4. GEANT4 used for neutron beam design of a neutron imaging facility at TRIGA reactor in Morocco

    Energy Technology Data Exchange (ETDEWEB)

    Ouardi, A., E-mail: ouardi@cnesten.org.ma [Centre National de l' Energie, des Science et des Techniques Nucleaire, B.P. 1382 R.P. 10001 (Morocco); Machmach, A. [Physics Department, University Hassan II faculte des Science of Ain Chock, Casablanca 5366 (Morocco); Alami, R.; Bensitel, A. [Centre National de l' Energie, des Science et des Techniques Nucleaire, B.P. 1382 R.P. 10001 (Morocco); Hommada, A. [Physics Department, University Hassan II faculte des Science of Ain Chock, Casablanca 5366 (Morocco)

    2011-09-21

    Neutron imaging has a broad scope of applications and has played a pivotal role in visualizing and quantifying hydrogenous masses in metallic matrices. The field continues to expand into new applications with the installation of new neutron imaging facilities. In this scope, a neutron imaging facility for computed tomography and real-time neutron radiography is currently being developed around 2.0MW TRIGA MARK-II reactor at Maamora Nuclear Research Center in Morocco (Reuscher et al., 1990 ; de Menezes et al., 2003 ; Deinert et al., 2005 ). The neutron imaging facility consists of neutron collimator, real-time neutron imaging system and imaging process systems. In order to reduce the gamma-ray content in the neutron beam, the tangential channel was selected. For power of 250 kW, the corresponding thermal neutron flux measured at the inlet of the tangential channel is around 3x10{sup 11} ncm{sup 2}/s. This facility will be based on a conical neutron collimator with two circular diaphragms with diameters of 4 and 2 cm corresponding to L/D-ratio of 165 and 325, respectively. These diaphragms' sizes allow reaching a compromise between good flux and efficient L/D-ratio. Convergent-divergent collimator geometry has been adopted. The beam line consists of a gamma filter, fast neutrons filter, neutron moderator, neutron and gamma shutters, biological shielding around the collimator and several stages of neutron collimator. Monte Carlo calculations by a fully 3D numerical code GEANT4 were used to design the neutron beam line ( (http://www.info.cern.ch/asd/geant4/geant4.html)). To enhance the neutron thermal beam in terms of quality, several materials, mainly bismuth (Bi) and sapphire (Al{sub 2}O{sub 3}) were examined as gamma and neutron filters respectively. The GEANT4 simulations showed that the gamma and epithermal and fast neutron could be filtered using the bismuth (Bi) and sapphire (Al{sub 2}O{sub 3}) filters, respectively. To get a good cadmium ratio, GEANT 4

  5. GEANT4 used for neutron beam design of a neutron imaging facility at TRIGA reactor in Morocco

    International Nuclear Information System (INIS)

    Neutron imaging has a broad scope of applications and has played a pivotal role in visualizing and quantifying hydrogenous masses in metallic matrices. The field continues to expand into new applications with the installation of new neutron imaging facilities. In this scope, a neutron imaging facility for computed tomography and real-time neutron radiography is currently being developed around 2.0MW TRIGA MARK-II reactor at Maamora Nuclear Research Center in Morocco (Reuscher et al., 1990 ; de Menezes et al., 2003 ; Deinert et al., 2005 ). The neutron imaging facility consists of neutron collimator, real-time neutron imaging system and imaging process systems. In order to reduce the gamma-ray content in the neutron beam, the tangential channel was selected. For power of 250 kW, the corresponding thermal neutron flux measured at the inlet of the tangential channel is around 3x1011 ncm2/s. This facility will be based on a conical neutron collimator with two circular diaphragms with diameters of 4 and 2 cm corresponding to L/D-ratio of 165 and 325, respectively. These diaphragms' sizes allow reaching a compromise between good flux and efficient L/D-ratio. Convergent-divergent collimator geometry has been adopted. The beam line consists of a gamma filter, fast neutrons filter, neutron moderator, neutron and gamma shutters, biological shielding around the collimator and several stages of neutron collimator. Monte Carlo calculations by a fully 3D numerical code GEANT4 were used to design the neutron beam line ( (http://www.info.cern.ch/asd/geant4/geant4.html)). To enhance the neutron thermal beam in terms of quality, several materials, mainly bismuth (Bi) and sapphire (Al2O3) were examined as gamma and neutron filters respectively. The GEANT4 simulations showed that the gamma and epithermal and fast neutron could be filtered using the bismuth (Bi) and sapphire (Al2O3) filters, respectively. To get a good cadmium ratio, GEANT 4 simulations were used to define the design

  6. GEANT4 used for neutron beam design of a neutron imaging facility at TRIGA reactor in Morocco

    Science.gov (United States)

    Ouardi, A.; Machmach, A.; Alami, R.; Bensitel, A.; Hommada, A.

    2011-09-01

    Neutron imaging has a broad scope of applications and has played a pivotal role in visualizing and quantifying hydrogenous masses in metallic matrices. The field continues to expand into new applications with the installation of new neutron imaging facilities. In this scope, a neutron imaging facility for computed tomography and real-time neutron radiography is currently being developed around 2.0MW TRIGA MARK-II reactor at Maamora Nuclear Research Center in Morocco (Reuscher et al., 1990 [1]; de Menezes et al., 2003 [2]; Deinert et al., 2005 [3]). The neutron imaging facility consists of neutron collimator, real-time neutron imaging system and imaging process systems. In order to reduce the gamma-ray content in the neutron beam, the tangential channel was selected. For power of 250 kW, the corresponding thermal neutron flux measured at the inlet of the tangential channel is around 3×10 11 ncm 2/s. This facility will be based on a conical neutron collimator with two circular diaphragms with diameters of 4 and 2 cm corresponding to L/D-ratio of 165 and 325, respectively. These diaphragms' sizes allow reaching a compromise between good flux and efficient L/D-ratio. Convergent-divergent collimator geometry has been adopted. The beam line consists of a gamma filter, fast neutrons filter, neutron moderator, neutron and gamma shutters, biological shielding around the collimator and several stages of neutron collimator. Monte Carlo calculations by a fully 3D numerical code GEANT4 were used to design the neutron beam line ( http://www.info.cern.ch/asd/geant4/geant4.html[4]). To enhance the neutron thermal beam in terms of quality, several materials, mainly bismuth (Bi) and sapphire (Al 2O 3) were examined as gamma and neutron filters respectively. The GEANT4 simulations showed that the gamma and epithermal and fast neutron could be filtered using the bismuth (Bi) and sapphire (Al 2O 3) filters, respectively. To get a good cadmium ratio, GEANT 4 simulations were used to

  7. A new technique for neutron monitoring in stray radiation fields

    International Nuclear Information System (INIS)

    At reactors, accelerators and therapy facilities including linear accelerators there is the need to monitor low level stray radiation fields, Neutron monitoring today is based mainly on the application of rem counters. A new approach to neutron monitoring is described which allows one to measure the dose equivalent of neutrons and gamma rays and to interpret neutron spectra in stray radiation fields in terms of Esub(e)sub(f)sub(f) and the dose fractnon of thermat neutrons. Compared to the muttisphere technique only a single moderator sphere of 30 cm diam and various pairs of TLD600/TLD7O0 detectors as passive neutron/gamma detectors are applied to measure moderated neutrons in the center of the sphere, backscattered albedo neutrons on the surface of the sphere and thermal as well as epithermal neutrons from the stray radiation field directly. The passive dosimeter system is sensitive to neutrons in the dose range 10 mrem - 500 rem and permits long-term exposures of several months. Field exposures performed at different facilities are described showing representative results for a neutron stray radiation field with Esub(e)sub(f)sub(f) between 2 MeV down to 100 keV and dose contributions from thermal neutrons between 1% and 30% depending on the kind of neutron stray source, the distance from the source, and the concrete shieldings in the room. (H.K.)

  8. Statistics of neutrons data based on Dempster-Shafer theory

    International Nuclear Information System (INIS)

    Because of limited sample numbers, imprecise data and dynamic error, statistical method based on probability theory has some shortage in neutrons data processing. Based on Dempster-Shafer (D-S) theory, a method of statistics of neutrons data is described. Appling the basic assign, belief function and plausible function, the lower and upper probability for neutrons randomly distribute to some sets was presented, so was the average neutrons number. The new method of statistics is especially suitable for imprecise data and not restricted by sample numbers

  9. Neutron Sources for Standard-Based Testing

    Energy Technology Data Exchange (ETDEWEB)

    Radev, Radoslav [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McLean, Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-11-10

    The DHS TC Standards and the consensus ANSI Standards use 252Cf as the neutron source for performance testing because its energy spectrum is similar to the 235U and 239Pu fission sources used in nuclear weapons. An emission rate of 20,000 ± 20% neutrons per second is used for testing of the radiological requirements both in the ANSI standards and the TCS. Determination of the accurate neutron emission rate of the test source is important for maintaining consistency and agreement between testing results obtained at different testing facilities. Several characteristics in the manufacture and the decay of the source need to be understood and accounted for in order to make an accurate measurement of the performance of the neutron detection instrument. Additionally, neutron response characteristics of the particular instrument need to be known and taken into account as well as neutron scattering in the testing environment.

  10. Applications of image plates in neutron radiography and neutron diffraction at BARC, Trombay

    International Nuclear Information System (INIS)

    Neutron radiography techniques based on Gd, Dy and In metallic foils and X-ray film have been used at this centre since early seventies for various NDT and R and D work in nuclear, defence and aerospace industries. In recent years use of photostimulated luminescence based phosphor imaging plate has been introduced in our work. This has enabled to achieve higher sensitivities and dynamic ranges of recording radiographs with acceptable spatial resolution. It also provides digital image information which is more convenient for quantitative evaluations. Neutron image plates have been used in variety of radiography techniques such as conventional neutron radiography (NR), neutron induced beta radiography (NIBR), hydrogen sensitive epithermal neutron radiography (HYSEN) and for neutron powder diffractometry using Apsara, CIRUS and Dhruva reactors as neutron sources. Recently the image plates have also been used for characterization of thermalized neutron beam from a plasma focus neutron source and recording neutron radiographs. Prior to the utilization image plates have been characterised for their performance. Details of the measurements and applications will be presented. (author)

  11. Improved Neutron Scintillators Based on Nanomaterials

    International Nuclear Information System (INIS)

    The development work conducted in this SBIR has so far not supported the premise that using nano-particles in LiFZnS:Ag foils improves their transparency to 420 (or other frequency) light. This conclusion is based solely on the light absorption properties of LiFZnS foils fabricated from nano- and from micro-particles. Furthermore, even for the case of the Gd2O3 foils, the transmission of 420 nm light gained by using nano-particles all but disappears as the foil thickness is increased beyond about 0.2 mm, a practical scintillator thickness. This was not immediately apparent from the preliminary study since no foils thicker than about 0.04 mm were produced. Initially it was believed that the failure to see an improvement by using nano-particles for the LiFZnS foils was caused by the clumping of the particles in Toluene due to the polarity of the ZnS particles. However, we found, much to our surprise, that nano-particle ZnS alone in polystyrene, and in Epoxy, had worse light transmission properties than the micro-particle foils for equivalent thickness and density foils. The neutron detection measurements, while disappointing, are attributable to our inability to procure or fabricate Bulk Doped ZnS nanoparticles. The cause for the failure of nano-particles to improve the scintillation light, and hence improved neutron detection efficiency, is a fundamental one of light scattering within the scintillator. A consequence of PartTec's documentation of this is that several concepts for the fabrication of improved 6LiFZnS scintillators were formulated that will be the subject of a future SBIR submission.

  12. Improved Neutron Scintillators Based on Nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Dennis Friesel, PhD

    2008-06-30

    The development work conducted in this SBIR has so far not supported the premise that using nano-particles in LiFZnS:Ag foils improves their transparency to 420 (or other frequency) light. This conclusion is based solely on the light absorption properties of LiFZnS foils fabricated from nano- and from micro-particles. Furthermore, even for the case of the Gd{sub 2}O{sub 3} foils, the transmission of 420 nm light gained by using nano-particles all but disappears as the foil thickness is increased beyond about 0.2 mm, a practical scintillator thickness. This was not immediately apparent from the preliminary study since no foils thicker than about 0.04 mm were produced. Initially it was believed that the failure to see an improvement by using nano-particles for the LiFZnS foils was caused by the clumping of the particles in Toluene due to the polarity of the ZnS particles. However, we found, much to our surprise, that nano-particle ZnS alone in polystyrene, and in Epoxy, had worse light transmission properties than the micro-particle foils for equivalent thickness and density foils. The neutron detection measurements, while disappointing, are attributable to our inability to procure or fabricate Bulk Doped ZnS nanoparticles. The cause for the failure of nano-particles to improve the scintillation light, and hence improved neutron detection efficiency, is a fundamental one of light scattering within the scintillator. A consequence of PartTec's documentation of this is that several concepts for the fabrication of improved {sup 6}LiFZnS scintillators were formulated that will be the subject of a future SBIR submission.

  13. Neutron dosimetry based on nuclear track etched detectors

    Energy Technology Data Exchange (ETDEWEB)

    Bouassoule, T.; Fernandez, F.; Marin, M.; Tomas, M. [Grup de Fisica de les Radiacions. Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)

    1999-07-01

    In this work, the response of a neutron dosimeter based on plastic track detectors has been studied. The detector geometry used consists on a C R-39 detector 500 m thick plus either a Makrofol converter 300 {mu} m thick or air used as converter, for the study of the response to fast or thermal neutrons respectively. The possibility of using Makrofol as a high energy neutron dosemeter has also been studied. In order to validate the results obtained from Monte Carlo simulations, a set of irradiations to monoenergetic neutron beams has been performed at the Ptb and to realistic fields at Cadarache neutron irradiation facilities. An excellent agreement has been found between the simulated and the experimental values. The lower detection limit value found for C R-39 and fast neutrons was 60 {mu} Sv. (Author)

  14. Neutron beam monitor based on a boron-coated GEM

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jian-Rong; LI Yi; SUN Zhi-Jia; LIU Ben; WANG Yan-Feng; YANG Gui-An; ZHOU Liang; XU Hong; DONG Jing; YANG Lei

    2011-01-01

    A new thermal neutron beam monitor with a Gas Electron Multiplier (GEM) is developed to meet the needs of the next generation of neutron facilities. A prototype chamber has been constructed with two 100 mm×100 mm GEM foils. Enriched boron-10 is coated on one surface of the aluminum cathode plate as the neutron convertor. 96 channel pads with an area of 8 mm×8 mm each are used for fast signal readout.In order to study the basic characteristics of a boron-coated GEM, several irradiation tests were carried out with α source 239pu and neutron source 241Am(Be). The signal induced by the neutron source has a high signal-to-noise ratio. A clear image obtained from α source 239pu is presented, which shows that the neutron beam monitor based on a boron-coated GEM has a good two-dimensional imaging ability.

  15. IEC-based neutron generator for security inspection system

    International Nuclear Information System (INIS)

    Use of a combined X-ray and neutron source for security inspections based on Inertial Electrostatic Confinement (IEC) fusion is discussed. Current inspection systems typically use X-ray techniques, but thermal neutron analysis (TNA) and fast neutron analysis (FNA), allow expanded detection of certain types of explosives. The integrated unit proposed here uses three separate IEC sources producing 14 and 2.45 MeV neutrons plus soft X-rays. This combination allows multiple detection methods with the composite signal analysis being done by a fuzzy logic system, significantly reducing false signals. (author)

  16. Neutron detection based on superheated materials

    International Nuclear Information System (INIS)

    The environmental and radiation responses of the Active Personnel Dosimeter/Superheated Drop Detector (APD/SDD) combination have been evaluated at the Pacific Northwest Laboratory (PNL) for the US Department of Energy's Neutron Measurement and Evaluation Program. This paper provides results of the evaluation and discusses possible improvements for the current system. Radiation detection based on the radiation sensitivity of superheated liquids has been studied for some time. A liquid is superheated if it exists as a liquid at a temperature-pressure state normally associated with the vapor phase of that material. The liquid does not vaporize because there are no bubble nucleation sites in the sample. These sites usually exist (1) in microscopic cracks on solid container surfaces, (2) in crevices of imperfectly wetted solid particles suspended in the liquid, or (3) as a result of the radiation-matter interaction producing a microbubble that is large enough for bubble growth to be thermodynamically favorable. By suspending small drops of superheated liquid in an immiscible, inert, impurity-free medium, potential for bubble nucleation by the first two mechanisms is eliminated. Therefore, each drop becomes a miniature radiation detector

  17. Neutron detection based on superheated materials

    International Nuclear Information System (INIS)

    The environmental and radiation responses of the Active Personnel Dosimeter/Superheated Drop Detector (APD/SDD) combination have been evaluated at the Pacific Northwest Laboratory (PNL) for the U.S. Department of Energy's Neutron Measurement and Evaluation Program. This paper provides results of the evaluation and discusses possible improvements for the current system. Radiation detection based on the radiation sensitivity of superheated liquids has been studied for some time. A liquid is superheated if it exists as a liquid at a temperature-pressure state normally associated with the vapor phase of that material. The liquid does not vaporize because there are no bubble nucleation sits in the sample. These sites usually exist in microscopic cracks on solid container surfaces, in crevices of imperfectly wetted solid particles suspended in the liquid, or as a result of the radiation-matter interaction producing a microbubble that is large enough for bubble growth to be thermodynamically favorable. By suspending small drops of superheated liquid in an immiscible, inert, impurity-free medium, potential for bubble nucleation by the first two mechanisms is eliminated. Therefore, each drop becomes a miniature radiation detector

  18. Accelerator-based neutron radioscopic systems

    International Nuclear Information System (INIS)

    There is interest in non-reactor source, thermal neutron inspection systems for applications in aircraft maintenance, explosive devices, investment-cast turbine blades, etc. Accelerator sources, (d-T), RFQ accelerators and cyclotrons as examples, are available for either transportable or fixed neutron inspection systems. Sources are reviewed for neutron output, portability, ease of use and cost, and for use with an electronic neutron imaging camera (image intensifier or scintillator-camera system) to provide a prompt response, neutron inspection system. Particular emphasis is given to the current aircraft inspection problem to detect and characterize corrosion. Systems are analyzed to determine usefulness in providing an on-line inspection technique to detect corrosion in aluminum honeycomb aircraft components, either on-aircraft or in a shop environment. The neutron imaging sensitivity to hydrogenous aluminum corrosion product offers early detection advantages for aircraft corrosion, to levels of aluminum metal loss as small as 25 μm. The practical capability for a continuous scan thermal neutron radioscopic system to inspect up to 500 square feet of component surface per day is used as an evaluation criterion, with the system showing contrast sensitivity of at least 5% and image detail in the order of 4 mm for parts 10 cm thick. Under these practical conditions and 3-shift operation, the source must provide an incident thermal neutron flux of 5.6x104 n cm-2 s-1 at an L/D of 30. A stop and go inspection approach, offering improved resolution, would require a source with similar characteristics

  19. Principles and applications of neutron based inspection techniques

    International Nuclear Information System (INIS)

    Neutron based explosive inspection systems can detect a wide variety of substances of importance, for a variety of purposes from national security threats (e.g., nuclear materials, explosives, narcotics) to customs duties, shipment control and validation, and for protection of the environment. The inspection is generally founded on the nuclear interactions of the neutrons with the various nuclides present and the detection of resultant characteristic emissions. These can be discrete gamma lines resulting from the thermal (n,γ) neutron capture process or inelastic neutron scattering (n,n'γ) occurring with fast neutrons. The two types of reactions are generally complementary. The capture process provides energetic and highly penetrating gamma rays in most inorganic substances and in hydrogen, while fast neutron inelastic scattering provides relatively strong gamma-ray signatures in light elements such as carbon and oxygen. In some specific important cases, though, unique signatures are provided by the neutron capture process in light elements such as nitrogen, where unusually high energy gamma rays are produced. This forms the basis for key explosive detection techniques. The detection of nuclear materials, both fissionable (e.g., 238U) and fissile (e.g., 235U), are generally based on the fissions induced by the probing neutrons and detecting one or more of the unique signatures of the fission process. These include prompt and delayed neutrons and prompt and delayed gamma rays. These signatures are not discrete in energy (typically they are continua) but temporally and energetically significantly different from the background, thus making them readily distinguishable. The penetrability of fast neutrons as probes and the gamma rays and fission neutrons as signatures make neutron interrogation applicable for large conveyances such as cars, trucks and marine containers. The neutron-based techniques can be used in a variety of scenarios and operational modes. They can

  20. Principles and applications of neutron based inspection techniques

    International Nuclear Information System (INIS)

    Neutron based explosive inspection systems can detect a wide variety of substances of importance for a variety of purposes from national security threats (e.g., nuclear materials, explosives, narcotics) to customs dutiable goods, to hazardous substances to protect the environment. The inspection is generally founded on the nuclear interactions of the neutrons with the various nuclides present and the detection of resultant characteristic emissions. These can be discrete γ lines resulting from the thermal (n, γ) neutron capture process or inelastic neutron scattering (n, n'γ) occurring with fast neutrons. The two types of reactions are generally complementary. The capture process provides energetic and highly penetrating γ rays in most inorganic substances and hydrogen. Fast neutrons inelastic scattering provide relatively strong γ-ray signatures in light elements such as carbon and oxygen. In some specific important cases, unique signatures are provided by the neutron (n, γ) process in light elements such as nitrogen, where unusually high-energy γ rays are produced. This forms the basis for key explosive detection techniques. The detection of nuclear materials, both fissionable (e.g., 238U) and fissile (e.g., 235U), is generally based on the fissions induced by the probing neutrons and detecting one or more of the unique signatures of the fission process. These include prompt and delayed neutrons and prompt and delayed γ rays. These signatures are not discrete in energy (typically they are continua) but temporally and energetically significantly different from the background, thus making them readily distinguishable. The penetrability of fast neutrons as probes, and the γ rays and fission neutrons as signatures makes neutron interrogation applicable to the inspection of large conveyances such as cars, trucks, and marine containers. Neutron based inspection techniques have a broad applications. They can be used as stand-alone for complete scans of objects

  1. Thermal Neutron Imaging Using A New Pad-Based Position Sensitive Neutron Detector

    Energy Technology Data Exchange (ETDEWEB)

    Dioszegi I.; Vanier P.E.; Salwen C.; Chichester D.L.; Watson S.M.

    2016-10-29

    Thermal neutrons (with mean energy of 25 meV) have a scattering mean free path of about 20 m in air. Therefore it is feasible to find localized thermal neutron sources up to ~30 m standoff distance using thermal neutron imaging. Coded aperture thermal neutron imaging was developed in our laboratory in the nineties, using He-3 filled wire chambers. Recently a new generation of coded-aperture neutron imagers has been developed. In the new design the ionization chamber has anode and cathode planes, where the anode is composed of an array of individual pads. The charge is collected on each of the individual 5x5 mm2 anode pads, (48x48 in total, corresponding to 24x24 cm2 sensitive area) and read out by application specific integrated circuits (ASICs). The high sensitivity of the ASICs allows unity gain operation mode. The new design has several advantages for field deployable imaging applications, compared to the previous generation of wire-grid based neutron detectors. Among these are the rugged design, lighter weight and use of non-flammable stopping gas. For standoff localization of thermalized neutron sources a low resolution (11x11 pixel) coded aperture mask has been fabricated. Using the new larger area detector and the coarse resolution mask we performed several standoff experiments using moderated californium and plutonium sources at Idaho National Laboratory. In this paper we will report on the development and performance of the new pad-based neutron camera, and present long range coded-aperture images of various thermalized neutron sources.

  2. A target-moderator-reflector concept of the JAERI 5 MW pulsed spallation neutron source

    International Nuclear Information System (INIS)

    In Japan Atomic Energy Research Institute the construction of a 5 MW (short) pulsed spallation neutron source is under planning using a projected high power superconducting proton (or H-) linac of 8 MW in total beam power. In the present paper we report our consideration on target-moderator-reflector concept, based on the layout of the tentative neutron instruments for the assumed neutron scattering experiments in future. The choice of cold neutron moderators for high resolution and high intensity experiments, thermal and epithermal neutron moderators for high resolution uses was discussed and a reference layout of target-moderator-reflector system was proposed for detailed neutronic calculation and optimization. The proposed system was designed like that it can provide, at least, 30 beam lines for more than 40 instruments. (author)

  3. A target-moderator-reflector concept of the JAERI 5 MW pulsed spallation neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Noboru; Teshigawara, Makoto; Aizawa, Kazuya; Suzuki, Jyunichi; Oyama, Yukio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    In Japan Atomic Energy Research Institute the construction of a 5 MW (short) pulsed spallation neutron source is under planning using a projected high power superconducting proton (or H{sup -}) linac of 8 MW in total beam power. In the present paper we report our consideration on target-moderator-reflector concept, based on the layout of the tentative neutron instruments for the assumed neutron scattering experiments in future. The choice of cold neutron moderators for high resolution and high intensity experiments, thermal and epithermal neutron moderators for high resolution uses was discussed and a reference layout of target-moderator-reflector system was proposed for detailed neutronic calculation and optimization. The proposed system was designed like that it can provide, at least, 30 beam lines for more than 40 instruments. (author)

  4. Design of an accelerator-based neutron source for neutron capture therapy

    International Nuclear Information System (INIS)

    The boron neutron capture therapy is mainly suited in the treatment of some tumor kinds which revealed ineffective to the traditional radiotherapy. In order to take advantage of such a therapeutic modality in hospital environments, neutron beams of suitable energy and flux levels provided by compact size facilities are needed. The advantages and drawbacks of several neutron beams are here analysed in terms of therapeutic gains. In detail the GEANT-3/MICAP simulations show that high tumor control probability, with sub-lethal dose at healthy tissues, can be achieved by using neutron beams of few keV energy having a flux of about 109 neutrons/(cm2 s). To produce such a neutron beam, the feasibility of a proton accelerator is investigated. In particular an appropriate choice of the radiofrequency parameters (modulation, efficiency of acceleration, phase shift, etc.) allows the development of relatively compact accelerators, having a proton beam current of 30 mA and an energy of 2 MeV, which could eventually lead to setting up of hospital-based neutron facilities.

  5. Thick target neutron yields for the 7Li(p,n)7Be reaction near threshold

    International Nuclear Information System (INIS)

    Transportable accelerator sources of epithermal neutrons are crucial for the development of hospital-based boron neutron capture therapy (BNCT) as a treatment modality for brain cancers. One method for producing such epithermal neutrons is near-threshold (p,n) reactions as studied by our group, as well as several other investigators. As part of this effort, we have developed accurate methods for computing the angular distributions and energy spectra of neutrons from thick targets using the 7Li(p,n)7Be reaction near threshold. Neutron yields are calculated for lithium metal as well as several lithium compounds of low molecular weight. The calculational method is discussed, with emphasis on the improvements over previously published methods. Neutron energy spectra, angular distributions, and total yields for proton beam energies up to 120 keV above threshold are presented. A method is also demonstrated for calculating neutron yields for targets that are not sufficiently thick to slow protons past the reaction threshold

  6. Data Assimilation of Benchmark Experiments for Homogenous Thermal / Epithermal Uranium Systems

    International Nuclear Information System (INIS)

    This presentation reports on the data assimilation of benchmark experiments for homogeneous thermal and epithermal uranium systems. The assimilation method is based on Kalman filters using integral parameters and sensitivity coefficients calculated with MONK9 and ENDF/B-VII data. The assimilation process results in an overall improvement of the calculation-benchmark agreement, and may help in the selection of nuclear data after analysis of adjustment trends

  7. ‘T’-type mineralisation : a pseudo-epithermal style of VHMS associated gold mineralisation, Cyprus

    OpenAIRE

    Jowitt, S.M.; Osborn, R.G.M.; Thomas, R.D.H.; Naden, J.; Gunn, A.G.; Herrington, R.J.; Nicolaides, S.

    2005-01-01

    A recent investigation of five VHMS prospects located in the Troodos ophiolite, Cyprus (Tourounjia, Alestos, Papoutsi, Kokkinovounaros and Agrokipia B), has indicated the possible presence of a pseudo-epithermal style of mineralisation. This is based on the presence of anomalous Au concentrations and hydrothermal brecciation. Short wavelength infrared (SWIR) analysis using a portable infrared mineral analyser (PIMA) was carried out to investigate the alteration mineralogy of these deposits an...

  8. Solid scintillator based neutron fluctuation measurement on EAST tokamak

    International Nuclear Information System (INIS)

    Microsecond level fast temporal resolved neutron flux and its fluctuation measurement system based on three types of solid scintillator detectors has been successfully established on the Experimental Advanced Superconducting Tokamak (EAST) for energetic particle (EP) and magnetohydrodynamics (MHD) instabilities relevant studies. The detector #1, where 50mm thick polyethylene is used for neutron thermalization, is mostly sensitive to thermal neutron. The detector #2 and #3 measure fast D-D neutrons directly with different gamma immunity. Design details together with detector test results with three types of radioisotope sources are presented. The system has been successfully implemented in EAST experiments for neutron and gamma identification. Typical fast MHD fluctuation related EAST experimental results from this system is also presented

  9. The conceptual calculation for the neutron beam device at Mark 1

    International Nuclear Information System (INIS)

    The thermal neutron beam device, epithermal neutron beam device and test duct experiment device are designed by using Monte Carlo method at 30 kW Mark 1(-1). The compared calculation for transverse cross section dimension, moderator, reflector and others of neutron filter device are studied in this paper. The three optimized neutron beams including thermal neutron beam, epithermal neutron beam and the beam for measuring blood boron density, whose neutron flux density per reactor power are rather high, are also introduced. The results show that the BNCT neutron beam can be designed by using 30kW -1 reactor. (author)

  10. Investigations on landmine detection by neutron-based techniques

    Energy Technology Data Exchange (ETDEWEB)

    Csikai, J. E-mail: csikai@delfin.klte.hu; Doczi, R.; Kiraly, B

    2004-07-01

    Principles and techniques of some neutron-based methods used to identify the antipersonnel landmines (APMs) are discussed. New results have been achieved in the field of neutron reflection, transmission, scattering and reaction techniques. Some conclusions are as follows: The neutron hand-held detector is suitable for the observation of anomaly caused by a DLM2-like sample in different soils with a scanning speed of 1 m{sup 2}/1.5 min; the reflection cross section of thermal neutrons rendered the determination of equivalent thickness of different soil components possible; a simple method was developed for the determination of the thermal neutron flux perturbation factor needed for multi-elemental analysis of bulky samples; unfolded spectra of elastically backscattered neutrons using broad-spectrum sources render the identification of APMs possible; the knowledge of leakage spectra of different source neutrons is indispensable for the determination of the differential and integrated reaction rates and through it the dimension of the interrogated volume; the precise determination of the C/O atom fraction requires the investigations on the angular distribution of the 6.13 MeV gamma-ray emitted in the {sup 16}O(n,n'{gamma}) reaction. These results, in addition to the identification of landmines, render the improvement of the non-intrusive neutron methods possible.

  11. A neutron spectrum unfolding code based on iterative procedures

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz R, J. M.; Vega C, H. R., E-mail: morvymm@yahoo.com.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Apdo. Postal 336, 98000 Zacatecas (Mexico)

    2012-10-15

    In this work, the version 3.0 of the neutron spectrum unfolding code called Neutron Spectrometry and Dosimetry from Universidad Autonoma de Zacatecas (NSDUAZ), is presented. This code was designed in a graphical interface under the LabVIEW programming environment and it is based on the iterative SPUNIT iterative algorithm, using as entrance data, only the rate counts obtained with 7 Bonner spheres based on a {sup 6}Lil(Eu) neutron detector. The main features of the code are: it is intuitive and friendly to the user; it has a programming routine which automatically selects the initial guess spectrum by using a set of neutron spectra compiled by the International Atomic Energy Agency. Besides the neutron spectrum, this code calculates the total flux, the mean energy, H(10), h(10), 15 dosimetric quantities for radiation protection porpoises and 7 survey meter responses, in four energy grids, based on the International Atomic Energy Agency compilation. This code generates a full report in html format with all relevant information. In this work, the neutron spectrum of a {sup 241}AmBe neutron source on air, located at 150 cm from detector, is unfolded. (Author)

  12. Epithermal neutron activation analysis of trace elements in biological materials

    International Nuclear Information System (INIS)

    The detection limits of 24 important minor and trace elements were studied in NBS SRM-1571 Orchard Leaves, NBS SRM-1577 Bovine Liver, Bowen's kale and IAEA H-4 Animal Muscle using ENAA method with cadmium and cadmium-boron filter. The lower detection limits have been found for elements As, Au, Ba, Br, Cd, Mo, Ni, Sb, Se, Sm and U by ENAA with cadmium filter and for elements As, Cd, Mo and Ni by ENAA with cadmium-boron filter, respectively, in comparison with INAA method. The results of the determination of elements studied in the above mentioned biological materials are also presented. (author)

  13. Neutrons in cancer therapy

    Science.gov (United States)

    Allen, Barry J.

    1995-03-01

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

  14. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy

    International Nuclear Information System (INIS)

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 105 n/cm2/s with sufficient accuracy. The SOF detector will be useful for phantom experiments with BNCT neutron fields from low-current accelerator-based neutron sources. (author)

  15. Development of beryllium-based neutron target system with three-layer structure for accelerator-based neutron source for boron neutron capture therapy.

    Science.gov (United States)

    Kumada, Hiroaki; Kurihara, Toshikazu; Yoshioka, Masakazu; Kobayashi, Hitoshi; Matsumoto, Hiroshi; Sugano, Tomei; Sakurai, Hideyuki; Sakae, Takeji; Matsumura, Akira

    2015-12-01

    The iBNCT project team with University of Tsukuba is developing an accelerator-based neutron source. Regarding neutron target material, our project has applied beryllium. To deal with large heat load and blistering of the target system, we developed a three-layer structure for the target system that includes a blistering mitigation material between the beryllium used as the neutron generator and the copper heat sink. The three materials were bonded through diffusion bonding using a hot isostatic pressing method. Based on several verifications, our project chose palladium as the intermediate layer. A prototype of the neutron target system was produced. We will verify that sufficient neutrons for BNCT treatment are generated by the device in the near future. PMID:26260448

  16. IEC-Based Neutron Generator for Security Inspection System

    International Nuclear Information System (INIS)

    Large nuclear reactors are widely employed for electricity power generation, but small nuclear radiation sources can also be used for a variety of industrial/government applications. In this paper we will discuss the use of a small neutron source based on Inertial Electrostatic Confinement (IEC) of accelerated deuterium ions. There is an urgent need of highly effective detection systems for explosives, especially in airports. While current airport inspection systems are strongly based on X-ray technique, neutron activation including Thermal Neutron Analysis (TNA) and Fast Neutron Analysis (FNA) is powerful in detecting certain types of explosives in luggage and in cargoes. Basic elements present in the explosives can be measured through the (n, n'?) reaction initiated by fast neutrons. Combined with a time-of-flight technique, a complete imaging of key elements, hence of the explosive materials, is obtained. Among the various neutron source generators, the IEC is an ideal candidate to meet the neutron activation analysis requirements. Compared with other accelerators and radioisotopes such as 252Cf, the IEC is simpler, can be switched on or off, and can reliably produce neutrons with minimum maintenance. Theoretical and experimental studies of a spherical IEC have been conducted at the University of Illinois. In a spherical IEC device, 2.54-MeV neutrons of ∼108 n/s via DD reactions over recent years or 14-MeV neutrons of ∼2x1010 n/s via DT reactions can be obtained using an ion gun injection technique. The possibility of the cylindrical IEC in pulsed operation mode combining with pulsed FNA method would also be discussed. In this paper we examine the possibility of using an alternative cylindrical IEC configuration. Such a device was studied earlier at the University of Illinois and it provides a very convenient geometry for security inspection. However, to calculate the neutron yield precisely with this configuration, an understanding of the potential wall

  17. Principles and status of neutron-based inspection technologies

    Science.gov (United States)

    Gozani, Tsahi

    2011-06-01

    Nuclear based explosive inspection techniques can detect a wide range of substances of importance for a wide range of objectives. For national and international security it is mainly the detection of nuclear materials, explosives and narcotic threats. For Customs Services it is also cargo characterization for shipment control and customs duties. For the military and other law enforcement agencies it could be the detection and/or validation of the presence of explosive mines, improvised explosive devices (IED) and unexploded ordnances (UXO). The inspection is generally based on the nuclear interactions of the neutrons (or high energy photons) with the various nuclides present and the detection of resultant characteristic emissions. These can be discrete gamma lines resulting from the thermal neutron capture process (n,γ) or inelastic neutron scattering (n,n'γ) occurring with fast neutrons. The two types of reactions are generally complementary. The capture process provides energetic and highly penetrating gamma rays in most inorganic substances and in hydrogen, while fast neutron inelastic scattering provides relatively strong gamma-ray signatures in light elements such as carbon and oxygen. In some specific important cases unique signatures are provided by the neutron capture process in light elements such as nitrogen, where unusually high-energy gamma ray is produced. This forms the basis for key explosive detection techniques. In some cases the elastically scattered source (of mono-energetic) neutrons may provide information on the atomic weight of the scattering elements. The detection of nuclear materials, both fissionable (e.g., 238U) and fissile (e.g., 235U), are generally based on the fissions induced by the probing neutrons (or photons) and detecting one or more of the unique signatures of the fission process. These include prompt and delayed neutrons and gamma rays. These signatures are not discrete in energy (typically they are continua) but temporally

  18. Soil-Carbon Measurement System Based on Inelastic Neutron Scattering

    International Nuclear Information System (INIS)

    Increase in the atmospheric CO2 is associated with concurrent increase in the amount of carbon sequestered in the soil. For better understanding of the carbon cycle it is imperative to establish a better and extensive database of the carbon concentrations in various soil types, in order to develop improved models for changes in the global climate. Non-invasive soil carbon measurement is based on Inelastic Neutron Scattering (INS). This method has been used successfully to measure total body carbon in human beings. The system consists of a pulsed neutron generator that is based on D-T reaction, which produces 14 MeV neutrons, a neutron flux monitoring detector and a couple of large NaI(Tl), 6'' diameter by 6'' high, spectrometers [4]. The threshold energy for INS reaction in carbon is 4.8 MeV. Following INS of 14 MeV neutrons in carbon 4.44 MeV photons are emitted and counted during a gate pulse period of 10 μsec. The repetition rate of the neutron generator is 104 pulses per sec. The gamma spectra are acquired only during the neutron generator gate pulses. The INS method for soil carbon content measurements provides a non-destructive, non-invasive tool, which can be optimized in order to develop a system for in field measurements

  19. GEM-based thermal neutron beam monitors for spallation sources

    Energy Technology Data Exchange (ETDEWEB)

    Croci, G., E-mail: Gabriele.Croci@cern.ch [Istituto di Fisica del Plasma “P. Caldirola”—CNR, Milan (Italy); Sez. INFN Milano-Bicocca, Milano (Italy); Claps, G. [Laboratori Nazionali di Frascati—INFN, Frascati (Italy); Caniello, R. [Istituto di Fisica del Plasma “P. Caldirola”—CNR, Milan (Italy); Cazzaniga, C. [Dipartimento di Fisica “G. Occhialini”, University of Milano-Bicocca (Italy); Grosso, G. [Istituto di Fisica del Plasma “P. Caldirola”—CNR, Milan (Italy); Murtas, F. [Laboratori Nazionali di Frascati—INFN, Frascati (Italy); Tardocchi, M.; Vassallo, E. [Istituto di Fisica del Plasma “P. Caldirola”—CNR, Milan (Italy); Gorini, G. [Dipartimento di Fisica “G. Occhialini”, University of Milano-Bicocca (Italy); Sez. INFN Milano-Bicocca, Milano (Italy); Horstmann, C.; Kampmann, R.; Nowak, G.; Stoermer, M. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht (Germany)

    2013-12-21

    The development of new large area and high flux thermal neutron detectors for future neutron spallation sources, like the European Spallation Source (ESS) is motivated by the problem of {sup 3}He shortage. In the framework of the development of ESS, GEM (Gas Electron Multiplier) is one of the detector technologies that are being explored as thermal neutron sensors. A first prototype of GEM-based thermal neutron beam monitor (bGEM) has been built during 2012. The bGEM is a triple GEM gaseous detector equipped with an aluminum cathode coated by 1μm thick B{sub 4}C layer used to convert thermal neutrons to charged particles through the {sup 10}B(n,{sup 7}Li)α nuclear reaction. This paper describes the results obtained by testing a bGEM detector at the ISIS spallation source on the VESUVIO beamline. Beam profiles (FWHM{sub x}=31 mm and FWHM{sub y}=36 mm), bGEM thermal neutron counting efficiency (≈1%), detector stability (3.45%) and the time-of-flight spectrum of the beam were successfully measured. This prototype represents the first step towards the development of thermal neutrons detectors with efficiency larger than 50% as alternatives to {sup 3}He-based gaseous detectors.

  20. Neutron based evaluation in support of NEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, Sven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bourke, Mark Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Losko, Adrian Simon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-06-07

    The primary objective of the Advanced Non-Destructive fuel Examination (ANDE) work package is to develop capability that has the potential to accelerate insight and development of ceramic and metallic fuels. Establishing unique validation opportunities for new models is a key component of this effort. To explore opportunities a series of interactions were held with NEAMS modelers at LANL. The focus was to identify experiments that draw on the unique capabilities of neutron scattering and imaging for studies of nuclear fuel particularly in areas where experimental data can be valuable for of models validation. The neutron characterization techniques applied in the ANDE program span length scales from millimeter to micrometer to angstroms. Spatial heterogeneities of interest include cracks, pores and inclusions, crystal structure, phase composition, stoichiometry texture, chemistry and atomic thermal motion. Neutrons offer characterization opportunities that are distinct from other probes such as X-rays, electrons or protons. This report describes a variety of opportunities whereby neutron data can be related to models and lists some opportunities.

  1. Event-based processing of neutron scattering data

    Science.gov (United States)

    Peterson, Peter F.; Campbell, Stuart I.; Reuter, Michael A.; Taylor, Russell J.; Zikovsky, Janik

    2015-12-01

    Many of the world's time-of-flight spallation neutrons sources are migrating to recording individual neutron events. This provides for new opportunities in data processing, the least of which is to filter the events based on correlating them with logs of sample environment and other ancillary equipment. This paper will describe techniques for processing neutron scattering data acquired in event mode which preserve event information all the way to a final spectrum, including any necessary corrections or normalizations. This results in smaller final uncertainties compared to traditional methods, while significantly reducing processing time and memory requirements in typical experiments. Results with traditional histogramming techniques will be shown for comparison.

  2. A new pad-based neutron detector for stereo coded aperture thermal neutron imaging

    Science.gov (United States)

    Dioszegi, I.; Yu, B.; Smith, G.; Schaknowski, N.; Fried, J.; Vanier, P. E.; Salwen, C.; Forman, L.

    2014-09-01

    A new coded aperture thermal neutron imager system has been developed at Brookhaven National Laboratory. The cameras use a new type of position-sensitive 3He-filled ionization chamber, in which an anode plane is composed of an array of pads with independent acquisition channels. The charge is collected on each of the individual 5x5 mm2 anode pads, (48x48 in total, corresponding to 24x24 cm2 sensitive area) and read out by application specific integrated circuits (ASICs). The new design has several advantages for coded-aperture imaging applications in the field, compared to the previous generation of wire-grid based neutron detectors. Among these are its rugged design, lighter weight and use of non-flammable stopping gas. The pad-based readout occurs in parallel circuits, making it capable of high count rates, and also suitable to perform data analysis and imaging on an event-by-event basis. The spatial resolution of the detector can be better than the pixel size by using a charge sharing algorithm. In this paper we will report on the development and performance of the new pad-based neutron camera, describe a charge sharing algorithm to achieve sub-pixel spatial resolution and present the first stereoscopic coded aperture images of thermalized neutron sources using the new coded aperture thermal neutron imager system.

  3. Progress in Mirror-Based Fusion Neutron Source Development

    OpenAIRE

    Anikeev, A. V.; Bagryansky, P. A.; Beklemishev, A.D.; Ivanov, A. A.; E. Yu. Kolesnikov; M. S. Korzhavina; O. A. Korobeinikova; Lizunov, A. A.; Maximov, V. V.; S. V. Murakhtin; E. I. Pinzhenin; Prikhodko, V. V.; E. I. Soldatkina; Solomakhin, A. L.; Tsidulko, Yu. A.

    2015-01-01

    The Budker Institute of Nuclear Physics in worldwide collaboration has developed a project of a 14 MeV neutron source for fusion material studies and other applications. The projected neutron source of the plasma type is based on the gas dynamic trap (GDT), which is a special magnetic mirror system for plasma confinement. Essential progress in plasma parameters has been achieved in recent experiments at the GDT facility in the Budker Institute, which is a hydrogen (deuterium) prototype of the...

  4. Monitor System for Neutron Room Based on Embedded System

    International Nuclear Information System (INIS)

    The strong radiation in neutron room limits the real-time monitoring and detection during the course of nuclear pipe aging. The paper introduced a new type of detection system with the characteristics of simple operation and large extensibility. The hardware of this system mainly consists of neutron pulse counting, the modules of video capturing, the parameter of temperature and humidity condition obtaining, and network communication, which is based on S3C2410 processor. (authors)

  5. Neutron spectrum measurements in the aluminum oxide filtered beam facility at the Brookhaven Medical Research Reactor

    International Nuclear Information System (INIS)

    Neutron spectrum measurements were performed on the aluminum oxide filter installed in the Brookhaven Medical Research Reactor (BMRR). For these measurements, activation foils were irradiated at the exit port of the beam facility. A technique based on dominant resonances in selected activation reactions was used to measure the epithermal neutron spectrum. The fast and intermediate-energy ranges of the neutron spectrum were measured by threshold reactions and 10B-shielded 235U fission reactions. Neutron spectral data were derived from the activation data by two approaches: (1) a short analysis which yields neutron flux values at the energies of the dominant or primary resonances in the epithermal activation reactions and integral flux data for neutrons above corresponding threshold or pseudo-threshold energies, and (2) the longer analysis which utilized all the activation data in a full-spectrum, unfolding process using the FERRET spectrum adjustment code. This paper gives a brief description of the measurement techniques, analysis methods, and the results obtained

  6. Neutron source based on the TORNADO trap

    International Nuclear Information System (INIS)

    The TORNADO magnetic trap as a source of thermonuclear neutrons with 108 neutron per a pulse in the D-D reaction is considered. The construction of magnetic traps both with stationary and quasistationary modes of their operation is shown to be possible. The results of numerical calculation of the magnetic system parameters are given, analysis of permissible mechanical loads, turns displacements of and magnetic fields in the trap is carried out. Considerable decrease of pondermotive forces affecting the turns of an internal spiral when conserving thermo-insulating properties of the magnetic trap field is shown to be possible. The loads of the trap spiral magnet coils are shown to be also acceptable to form the stationary magnetic field of the 2 Tl order in the magnetic barrier

  7. The physics experimental study for in-hospital neutron irradiator

    International Nuclear Information System (INIS)

    MNSRs (Miniature Neutron Source Reactor) are low power research reactors designed and manufactured by China Institute of Atomic Energy (CIAE). MNSRs are mainly used for NAA, training and teaching, testing of nuclear instrumentation. The first MNSR, the prototype MNSR, was put into operation in 1984, later, eight other MNSRs had been built both at home and abroad. For MNSRs, highly enriched uranium (90%) is used as the fuel material. The In-Hospital Neutron Irradiator (IHNI) is designed for Boron Neutron Capture Therapy (BNCT) based on Miniature Neutron Source Reactor(MNSR). On both sides of the reactor core, there are two neutron beams, one is thermal neutron beam, and the other opposite to the thermal beam, is epithermal neutron beam. A small thermal neutron beam is specially designed for the measurement of blood boron concentration by the prompt gamma neutron activation analysis (PGNAA). In this paper, the experimental results of critical mass worth of the top Be reflectors worth of the control rod, neutron flux distribution and other components worth were measured, the experiment was done on the Zero Power Experiment equipment of MNSR. (author)

  8. Personnel neutron dosimeters based on organic polymers

    International Nuclear Information System (INIS)

    Resonance Ionization Spectroscopy, RIS, is a photophysics process in which pulsed lasers are used to remove electrons from those types of atoms which are selected by tuning the laser. Such processes can be saturated and hence with detectors that are sensitive to single electrons or ions, one-atom detection (OAD) can be achieved. In this paper, the possible application of OAD to neutron dosimetry is examined

  9. Novel Boron Based Multilayer Thermal Neutron Detector

    CERN Document Server

    SCHIEBER, M

    2010-01-01

    The detector contains four or more layers of natural Boron absorbing thermal neutrons. Thickness of a layer is 0.4 - 1.2 mg/cm2. The layers are deposited on one or on both sides of a metal surface used as contacts. Between the absorbing layers there are gas-filled gaps 3 - 6 mm thick. Electric field of 100 - 200 V/cm is applied to the gas-filled gaps. Natural Boron contains almost 20% of 10B isotope. When atoms of 10B capture a thermal neutron, nuclear reaction occurs, as a result of which two heavy particles - alpha particle and ion 7Li - from the thin absorber layer are emitted in opposing sides. One of the two particles penetrates into gas-filled gap between Boron layers and ionizes the gas. An impulse of electric current is created in the gas-filled gap actuated by the applied electric field. The impulse is registered by an electronic circuit. We have made and tested detectors containing from two to sixteen layers of natural Boron with an efficiency of thermal neutron registration from 2.9% to 12.5% accor...

  10. Role of the TAPIRO fast research reactor in neutron capture therapy in Italy. Calculations and measurements

    International Nuclear Information System (INIS)

    For Neutron Capture Therapy (NCT) applications, many research reactors are presently utilized. Clinical trials are performed in thermal reactors that have been appropriately modified, in order to obtain convenient beams for Becton (Boron Neutron Capture Therapy), by means of proper filtering or spectrum shifting. However, the beam quality obtainable by fast reactors is expected to be better than that of thermal reactor facilities. Tapiro is a low power, high flux, highly enriched (93.5%) 235Uranium fast reactor. The power is 5 kw and the maximum neutron flux in the core is 3.2'1012 cm-2 s-1. A thermal column and an epithermal one have been designed and constructed, aimed at dosimetry and animal experiments. The configurations of the columns have been designed by means of calculations based on Monte Carlo with the codes MCNP4B and MCNPX2.1.5 together with the DSA (Direct Statistical Approach) variance reduction optimisation patch. The columns have been characterized by means of measurements performed with activation techniques and thermoluminescence and gel dosimeters. Experimental results have shown good consistency with calculations. Moreover, they have confirmed the good quality of the beams obtainable with such a reactor. The TAPIRO reactor (a) and the scheme of the epithermal column (b) are shown. To have further confirmation of the quality of the radiation field in the constructed epithermal column, in-phantom absorbed doses have been measured and profiled by means of gel dosimeters, separating the various dose contributions having different biological effects. An epithermal column for human clinical trials has been designed by means of Monte Carlo calculations and the construction is now in progress. A section of this column is shown and beam parameters are reported. It is evident that the beam quality of this column is satisfactory in comparison with the IAEA recommendations. Moreover, such parameters are good if compared with those available at the

  11. Polymer Nanocomposite Based Multi-layer Neutron Shields

    International Nuclear Information System (INIS)

    It is important to shield radiations generated from the various radiation sources including nuclear reactors, transportation and storage systems for the radioactive wastes, accelerator, hospital, and defense systems etc. In this regard, development of efficient, light and durable radiation shielding materials has been an issue for many years. High energy neutrons (fast neutrons) can be thermalized by colliding with the light elements such as hydrogen, and thermalized neutrons can be efficiently captured by neutron absorbers such as boron, lithium, or gadolinium, etc. To shield neutrons, it is common to use hydrogen rich polymer based shields containing thermal neutron absorbers. It is also necessary to shield secondary gamma radiations produced from nuclear reaction of neutrons with various materials. Hence, high density elements such as Fe, Pb, or W might be dispersed in the polymer base as well as with neutron absorbers at the same time. However, the particle sizes of these elements are in the range of several tens and hundreds micrometers causing possible leakage of radiation. To enhance radiation shielding efficiency, it is useful to use ultrafine particles to increase collision probability of radiation with the particles. Furthermore, it is theoretically possible to enhance radiation shielding efficiency by using the multi-layer structured shields whose constituents are different for each layer depending upon the shielding purpose under the same overall density. Also, material properties of the nanocomposites can be enhanced compared to the normal composites. This investigation is focused on characterization of the nanocomposite based multi-layer structured radiation shields compared to the conventional radiation shields

  12. Neutron Based Imaging and Element-mapping at the Budapest Neutron Centre

    Science.gov (United States)

    Kis, Z.; Szentmiklósi, L.; Belgya, T.; Balaskó, M.; Horváth, L. Z.; Maróti, B.

    The Budapest Neutron Centre (BNC) is a consortium of institutes to co-ordinate research activities carried out at the Budapest Research Reactor. It hosts two neutron imaging facilities (RAD and NORMA) operated by the Centre for Energy Research, Hungarian Academy of Sciences and offers access to this scientific infrastructure for the domestic and international users. The radiography station (RAD) at the thermal neutron beamline of the reactor gives a possibility to study relatively large objects by thermal neutron-, gamma- and X-ray radiography, and to benefit from the complementary features of the different radiations. RAD is being extended in 2014 with digital imaging and tomographic capabilities. The image detection is based on suitable converter screens. The static radiography and tomography images are acquired by a new, large area sCMOS camera, whereas the dynamic radiography is accomplished by a low-light-level TV camera and a frame grabber card. The NORMA facility is designed to perform neutron radiography and tomography on small samples using guided cold neutrons. Here two non-destructive techniques are coupled to determine the chemical composition and to visualize the internal structure of heterogeneous objects. The position-sensitive element analysis with prompt-gamma activation analysis (PGAA) and the imaging with neutron radiography/tomography (NR/NT) are integrated into a unique facility called NIPS-NORMA. The goal of such a combination of these methods is to save substantial beam time in the so-called NR/NT-driven PGAI (Prompt Gamma Activation Imaging) mode, in which the interesting regions are first visualized and located, and subsequently the time-consuming prompt-gamma measurements are made only where it is really needed. The paper will give an overview about the technical details of the facilities, and the latest results of selected applications from the fields of archaeometry, engineering and material science.

  13. Thermal neutron flux monitors based on vibrating wire

    Energy Technology Data Exchange (ETDEWEB)

    Arutunian, S.G., E-mail: femto@yerphi.am [Yerevan Physics Institute, Alikhanian Br. St. 2, Yerevan 0036 (Armenia); Bergoz, J. [Bergoz Instrumentation, 156 Rue du Mont Rond, 01630 (France); Chung, M., E-mail: mchung@unist.ac.kr [Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Harutyunyan, G.S.; Lazareva, E.G. [Yerevan Physics Institute, Alikhanian Br. St. 2, Yerevan 0036 (Armenia)

    2015-10-11

    Two types of neutron monitors with fine spatial resolutions are proposed based on vibrating wires. In the first type, neutrons interact with a vibrating wire, heat it, and lead to the change of its natural frequency, which can be precisely measured. To increase the heat deposition during the neutron scattering, the use of gadolinium layer that has the highest thermal neutron capture cross-section among all elements is proposed. The second type uses the vibrating wire as a “resonant target.” Besides the measurement of beam profile according to the average signal, the differential signal synchronized with the wire oscillations defines the beam profile gradient. The monitor's spatial resolution is defined by the wire's diameter.

  14. Proposal of thermal neutron flux monitors based on vibrating wire

    CERN Document Server

    Arutunian, S G; Chung, M; Harutyunyan, G S; Lazareva, E G

    2015-01-01

    Two types of neutron monitors with fine spatial resolution are proposed based on vibrating wire. In the first type, neutrons interact with the vibrating wire, heat it, and lead to the change of natural frequency, which can be precisely measured. To increase the heat deposition during the neutron scattering, use of gadolinium layer which has the highest thermal neutron capture cross section among all elements is proposed. The second type of the monitor uses vibrating wire as a resonant target. Besides the measurement of beam profile according to the average signal, the differential signal synchronized with the wire oscillations defines the gradient of beam profile. Spatial resolution of the monitor is defined by the diameter of the wire.

  15. Prototype of a large neutron detector based on MWPC

    Institute of Scientific and Technical Information of China (English)

    TIAN LiChao; QI HuiRong; SUN ZhiJia; WANG YanFeng; ZHANG Jian; LIU RongGuang; ZHAO YuBin

    2014-01-01

    A prototype of large-area position sensitive neutron detector was designed and constructed according to the requirements of the Small-Angle Scattering spectrometer of China Spallation Neutron Source (CSNS).The detector was based on the 3He neutron convertor and MWPC with an effective area of 650 mm×650 mm.A prototype was completed and tested with 55Fe X-ray.The high-pressure vessel was designed and constructed with high-strength aluminum alloy.A position resolution of about 4.6 mm×2.3 mm (FWHM) and efficiency > 65% for neutrons with wavelength of 1.8(A) was determined after the operational gas filled.

  16. A neutron spectrometry and dosimetry computer tool based on ANN

    International Nuclear Information System (INIS)

    In the neutron spectrometry and dosimetry research areas by means of the Bonner spheres spectrometric system utilizing classical approaches, such as Monte Carlo, parametrization and iterative procedures, the weight, time consuming procedure, the need to use an unfolding procedure, the low resolution spectrum, and the need to use the neutron fluence-to-dose conversion coefficients for calculating the equivalent doses are some drawbacks which these approaches offer. Each of the mentioned difficulties has motivated the development of complementary procedures such as maximum entropy, genetic algorithms and artificial neural networks. The use of neural networks to unfold neutron spectra and to calculate equivalent doses from the count rates measured with BSS system has become in an alternative procedure, which has been applied with success, however, it is observed that doesn't exist computer tools based on ANN technology to unfold neutron spectra and to calculate equivalent doses. In this work a customized front end user interface software application, called Neutron Spectrometry and Dosimetry by means of Artificial Neural Networks (NSDANN) based on ANN technology, is presented, which is capable to unfold neutron spectra and to simultaneously calculate 13 equivalent doses, by using only the count rates of a BBS system as input, in just a few seconds. (author)

  17. A study of neutron fluence rates of the BNCT beam at THOR using foil activation

    International Nuclear Information System (INIS)

    Neutron fluence rates of the BNCT epithermal neutron beam at THOR were measured by using double-foil activation method free-in-air and in a water phantom. Foil sets consisting of gold, copper and manganese were used for measurements. Copper was used as an extra detector for quality check. Monte Carlo calculations using the MCNP4C code were conducted to support and compare with the measurement results. It was found that the calculation of reaction rates of foils free-in-air based on a neutron source with a coarse group energy structure is inadequate. The meetness of the assumptions on the neutron energy distribution made in the double-foil formulation for the determination of neutron fluence rates must be estimated in order to compare with the calculation. (author)

  18. Notes on neutron flux measurement; Notas sobre medida de flujos neutronicos

    Energy Technology Data Exchange (ETDEWEB)

    Alcala Ruiz, F.

    1984-07-01

    The main purpose of this work is to get an useful guide to carry out topical neutron flux measurements. Although the foil activation technique is used in the majority of the cases, other techniques, such as those based on fission chambers and self-powered neutron detectors, are also shown. Special interest is given to the description and application of corrections on the measurement of relative and absolute induced activities by several types of detectors (scintillators, G-M and gas proportional counters). The thermal arid epithermal neutron fluxes, as determined in this work, are conventional or effective (West cots fluxes), which are extensively used by the reactor experimentalists; however, we also give some expressions where they are related to the integrated neutron fluxes, which are used in neutron calculations. (Author) 16 refs.

  19. The stationary neutron radiography system: a TRIGA-based production neutron radiography facility

    International Nuclear Information System (INIS)

    General Atomics (GA) is under contract to construct a Stationary Neutron Radiography System (SNRS) - on a turnkey basis - at McClellan Air Force Base in Sacramento, California. The SNRS is a custom designed neutron radiography system which will utilize a 1000 KW TRIGA reactor as the neutron source. The partially below-ground reactor will be equipped with four inclined beam tubes originating near the top of the reactor graphite reflector and installed tangential to the reactor core to provide a strong current of thermal neutrons with minimum gamma ray contamination. The inclined beam tubes will terminate in four large bays and will interface with rugged component positioning systems designed to handle intact aircraft wings, other honeycomb aircraft structures, and pyrotechnics. The SNRS will be equipped with real-time, near real-time, and film radiographic imaging systems to provide a broad spectrum of capability for detection of entrained moisture or corrosion in large aircraft panels. GA is prime contractor to the Air Force for the SNRS and is specifically responsible for the TRIGA reactor system and a portion of the neutron beam system design. Science Applications International Corporation and the Lionakis-Beaumont Design Group are principal subcontractors to GA on the project. (author)

  20. A comparison of neutron beams for BNCT based on in-phantom neutron field assessment parameters

    International Nuclear Information System (INIS)

    In this paper our in-phantom neutron field assessment parameters, T and DTumor, were used to evaluate several neutron sources for use in BNCT. Specifically, neutron fields from The Ohio State University (OSU) Accelerator-Based Neutron Source (ABNS) design, two alternative ABNS designs from the literature (the Al/AlF3-Al2O3 ABNS and the 7LiF-Al2O3 ABNS), a fission-convertor plate concept based on the 500-kW OSU Research Reactor (OSURR), and the Brookhaven Medical Research Reactor (BMRR) facility were evaluated. In order to facilitate a comparison of the various neutron fields, values of T and DTumor were calculated in a 14 cmx14 cmx14 cm lucite cube phantom located in the treatment port of each neutron source. All of the other relevant factors, such as phantom materials, kerma factors, and treatment parameters, were kept the same. The treatment times for the OSURR, the 7LiF-Al2O3 ABNS operating at a beam current of 10 mA, and the BMRR were calculated to be comparable and acceptable, with a treatment time per fraction of approximately 25 min for a four fraction treatment scheme. The treatment time per fraction for the OSU ABNS and the Al/AlF3-Al2O3 ABNS can be reduced to below 30 min per fraction for four fractions, if the proton beam current is made greater than approximately 20 mA. DTumor was calculated along the beam centerline for tumor depths in the phantom ranging from 0 to 14 cm. For tumor depths ranging from 0 to approximately 1.5 cm, the value of DTumor for the OSURR is largest, while for tumor depths ranging from 1.5 to approximately 14 cm, the value of DTumor for the OSU-ABNS is the largest

  1. Neutron transport model based on the transmission probability method

    International Nuclear Information System (INIS)

    Highlights: • One hexagonal assembly is divided into 6 triangular prisms in order to get accurate flux distributions. • Transmission probability method is applied to solve the integral neutron transport equation. • The neutron flux and source are expanded spatially by a set of second order orthogonal polynomials. • The neutron flux at the interface is approximated with simplified P1 approximation. - Abstract: A new project has been started recently at KIT to develop a code able to treat hexagonal-z geometries with low density regions. The mathematical method chosen for that purpose is the Transmission Probability Method (TPM) for solving the integral neutron transport equation. In this model, one hexagonal prism is divided into six or more triangular prisms in order to get accurate flux distributions. Within each triangular prism, the neutron source is assumed to be isotropic, the scalar flux and source being approximated in space with a set of second order orthogonal polynomials. The neutron flux at the interfaces is constant in space and approximated with the simplified P1 approximation in angle. A new code, TPM-HEXZ, based on the described model is developed and some benchmarks are used to verify the code, the results are in good agreement with reference ones

  2. Digital neutron image enhancement based on total variation-based ℓ0 minimization

    Science.gov (United States)

    Qiao, Shuang; Bai, Guanying; Sun, Jianing

    2016-01-01

    For the digital neutron radiography applications, low contrast is inevitable due to the neutron and photon statistics limited or high transmission (and low attenuation) in the sample. In this paper, we introduce a total variation-based ℓ0 minimization model and solve it by an alternating minimization approach. The proposed model is applied to base & detail decomposition for the dynamic range modification and detail magnification. Experimental results on several real neutron images are presented to demonstrate the effectiveness of the proposed method.

  3. Unfolding code for neutron spectrometry based on neural nets technology

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz R, J. M.; Vega C, H. R., E-mail: morvymm@yahoo.com.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Ingenieria Electrica, Apdo. Postal 336, 98000 Zacatecas (Mexico)

    2012-10-15

    The most delicate part of neutron spectrometry, is the unfolding process. The derivation of the spectral information is not simple because the unknown is not given directly as a result of the measurements. The drawbacks associated with traditional unfolding procedures have motivated the need of complementary approaches. Novel methods based on Artificial Neural Networks have been widely investigated. In this work, a neutron spectrum unfolding code based on neural nets technology is presented. This unfolding code called Neutron Spectrometry and Dosimetry by means of Artificial Neural Networks was designed in a graphical interface under LabVIEW programming environment. The core of the code is an embedded neural network architecture, previously optimized by the {sup R}obust Design of Artificial Neural Networks Methodology{sup .} The main features of the code are: is easy to use, friendly and intuitive to the user. This code was designed for a Bonner Sphere System based on a {sup 6}Lil(Eu) neutron detector and a response matrix expressed in 60 energy bins taken from an International Atomic Energy Agency compilation. The main feature of the code is that as entrance data, only seven rate counts measurement with a Bonner spheres spectrometer are required for simultaneously unfold the 60 energy bins of the neutron spectrum and to calculate 15 dosimetric quantities, for radiation protection porpoises. This code generates a full report in html format with all relevant information. (Author)

  4. Unfolding code for neutron spectrometry based on neural nets technology

    International Nuclear Information System (INIS)

    The most delicate part of neutron spectrometry, is the unfolding process. The derivation of the spectral information is not simple because the unknown is not given directly as a result of the measurements. The drawbacks associated with traditional unfolding procedures have motivated the need of complementary approaches. Novel methods based on Artificial Neural Networks have been widely investigated. In this work, a neutron spectrum unfolding code based on neural nets technology is presented. This unfolding code called Neutron Spectrometry and Dosimetry by means of Artificial Neural Networks was designed in a graphical interface under LabVIEW programming environment. The core of the code is an embedded neural network architecture, previously optimized by the Robust Design of Artificial Neural Networks Methodology. The main features of the code are: is easy to use, friendly and intuitive to the user. This code was designed for a Bonner Sphere System based on a 6Lil(Eu) neutron detector and a response matrix expressed in 60 energy bins taken from an International Atomic Energy Agency compilation. The main feature of the code is that as entrance data, only seven rate counts measurement with a Bonner spheres spectrometer are required for simultaneously unfold the 60 energy bins of the neutron spectrum and to calculate 15 dosimetric quantities, for radiation protection porpoises. This code generates a full report in html format with all relevant information. (Author)

  5. Introduction to Neutron Coincidence Counter Design Based on Boron-10

    Energy Technology Data Exchange (ETDEWEB)

    Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T.; Siciliano, Edward R.

    2012-01-22

    The Department of Energy Office of Nonproliferation Policy (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is ultimately to design, build and demonstrate a boron-lined proportional tube based alternative system in the configuration of a coincidence counter. This report, providing background information for this project, is the deliverable under Task 1 of the project.

  6. neutron radiography

    International Nuclear Information System (INIS)

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

  7. The orientation effect in the activities of neutronic probes

    International Nuclear Information System (INIS)

    The formulae relating activity and position of a neutron irradiated Indium foil, have been verified experimentally. Measurements with both thin and thick foils for epithermal neutrons and with thick foils for thermal neutrons have been carried out. The experimental results agree qualitatively with the theoretical predictions. (Author)

  8. Phantoms with 10BF3 detectors for boron neutron capture therapy applications

    International Nuclear Information System (INIS)

    Two acrylic cube phantoms have been constructed for BNCT applications that allow the depth distribution of neutrons to be measured with miniature 10BF3 detectors in 0.5-cm steps beginning at 1-cm depth. Sizes and weights of the cubes are 14 cm, 3.230 kg, and 11 cm, 1.567 kg. Tests were made with the epithermal neutron beam from the patient treatment port of the Brookhaven Medical Research Reactor. Thermal neutron depth profiles were measured with a bare 10BF3 detector at a reactor power of 50 W, and Cd-covered detector profiles were measured at a reactor power of 1 kW. The resulting plots of counting rate versus depth illustrate the dependence of neutron moderation on the size of the phantom. But more importantly the data can serve as benchmarks for testing the thermal and epithermal neutron profiles obtained with accelerator-based BNCT facilities. Such tests could be made with these phantoms at power levels about five orders of magnitude lower than that required for the treatment of patients with brain tumors. copyright 1998 American Association of Physicists in Medicine

  9. Fast neutron fields imaging with a CCD-based luminescent detector

    International Nuclear Information System (INIS)

    The paper considers some questions concerned with the development of an imaging system based on a CCD-detector for visualising fast neutron fields. From those the most important are: development of fast neutron screens, detector resistance to irradiation fields, and feasibility of fast neutron radiography and tomography at various neutron sources

  10. Fast neutron fields imaging with a CCD-based luminescent detector

    CERN Document Server

    Mikerov, V

    1999-01-01

    The paper considers some questions concerned with the development of an imaging system based on a CCD-detector for visualising fast neutron fields. From those the most important are: development of fast neutron screens, detector resistance to irradiation fields, and feasibility of fast neutron radiography and tomography at various neutron sources.

  11. Experimental investigation of thermal neutron analysis based landmine detection technology

    International Nuclear Information System (INIS)

    Background: Recently, the prompt gamma-rays neutron activation analysis method is wildly used in coal analysis and explosive detection, however there were less application about landmine detection using neutron method especially in the domestic research. Purpose: In order to verify the feasibility of Thermal Neutron Analysis (TNA) method used in landmine detection, and explore the characteristic of this technology. Methods: An experimental system of TNA landmine detection was built based on LaBr3 (Ce) fast scintillator detector and 252Cf isotope neutron source. The system is comprised of the thermal neutron transition system, the shield system, and the detector system. Results: On the basis of the TNA, the wide energy area calibration method especially to the high energy area was investigated, and the least detection time for a typical mine was defined. In this study, the 72-type anti-tank mine, the 500 g TNT sample and several interferential objects are tested in loess, red soil, magnetic soil and sand respectively. Conclusions: The experimental results indicate that TNA is a reliable demining method, and it can be used to confirm the existence of Anti-Tank Mines (ATM) and large Anti-Personnel Mines (APM) in complicated condition. (authors)

  12. Visualization of moisture in concrete based on neutron radiography

    International Nuclear Information System (INIS)

    As for the quantitative evaluation of moisture in cured concrete, there are several methods such as weighing method, sensor-using technique, and methods using various kinds of radiations. Although each method can attain general purposes, it is often impossible to express microscopic phenomena. The neutron radiography explained in this paper is a nondestructive measurement method for obtaining the transmission image of an object, by utilizing a difference in the attenuation characteristic caused by the interaction of neutrons with nuclei, and thus it can visualize the moisture behavior in concrete. The portion that contains a large amount of bound water in cured concrete is dark with low transmittance, and the portion with relatively high aggregates is bright. As for the effects of cracking of concrete on degradation phenomena, the analyzed image based on neutron radiography can be utilized because the image shows how moisture can be supplied under the change of moisture conditions. The neutron radiography that can be utilized in Japan's territory is nuclear reactors, but the reactors are currently not running. As alternative means, there are the use of radioisotopes, J-PARC as an accelerator, and RANS as a small neutron radiation source under development by RIKEN. (A.O.)

  13. International workshop on plasma-based neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-09

    The workshop was devoted to discussion of the status and future directions of work on plasma-based neutron sources. The workshop presentations demonstrated significant progress in development of the concepts of these sources and in broadening the required data base. Two main groups of neutron source designs were presented at the workshop: tokamak-based and mirror-based. Designs of the tokamak- based devices use the extensive data base generated during decades of tokamak research. Their plasma physics performance can be predicted with a high degree of confidence. On the other hand, they are relatively large and expensive, and best suited for Volumetric Neutron Sources (VNSes) or other large scale test facilities. They also have the advantage of being on the direct path to a power- producing reactor as presently conceived, although alternatives to the tokamak are presently receiving serious consideration for a reactor. The data base for the mirror-based group of plasma sources is less developed, but they are generally more flexible and, with appropriate selection of parameters, have the potential to be developed as compact Accelerated Test Facilities (ATFs) as well as full-scale VNSes. Also discussed at the workshop were some newly proposed but potentially promising concepts, like those based on the flow-through pinch and electrostatic ion-beam sources.

  14. Implementation of neutron phase contrast imaging at FRM-II

    International Nuclear Information System (INIS)

    At ANTARES, the beam line for neutron imaging at the Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM-II) in Garching, the option to do phase contrast imaging besides conventional absorption based neutron imaging was implemented and successfully used for the non-destructive testing of various types of objects. The used propagation-based technique is based on the interference of neutron waves in the detector plane that were differently strong diffracted by the sample. A comparison with other phase-sensitive neutron imaging techniques highlights assets and drawbacks of the different methods. In preliminary measurements at ANTARES and the spallation source SINQ at PSI in Villigen, the influence of the beam geometry, the neutron spectrum and the detector on the quality of the phase contrast measurements were investigated systematically. It was demonstrated that gamma radiation and epithermal neutrons in the beam contribute severely to background noise in measurements, which motivated the installation of a remotely controlled filter wheel for a quick and precise positioning of different crystal filters in the beam. By the installation of a similar aperture wheel, a quick change between eight different beam geometries was made possible. Besides pinhole and slit apertures, coded apertures based on non redundant arrays were investigated. The possibilities, which arise by the exploitation of the real part of the refractive index in neutron imaging, were demonstrated in experiments with especially designed test samples and in measurements with ordinary, industrial components. (orig.)

  15. Implementation of neutron phase contrast imaging at FRM-II

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, Klaus

    2008-11-12

    At ANTARES, the beam line for neutron imaging at the Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM-II) in Garching, the option to do phase contrast imaging besides conventional absorption based neutron imaging was implemented and successfully used for the non-destructive testing of various types of objects. The used propagation-based technique is based on the interference of neutron waves in the detector plane that were differently strong diffracted by the sample. A comparison with other phase-sensitive neutron imaging techniques highlights assets and drawbacks of the different methods. In preliminary measurements at ANTARES and the spallation source SINQ at PSI in Villigen, the influence of the beam geometry, the neutron spectrum and the detector on the quality of the phase contrast measurements were investigated systematically. It was demonstrated that gamma radiation and epithermal neutrons in the beam contribute severely to background noise in measurements, which motivated the installation of a remotely controlled filter wheel for a quick and precise positioning of different crystal filters in the beam. By the installation of a similar aperture wheel, a quick change between eight different beam geometries was made possible. Besides pinhole and slit apertures, coded apertures based on non redundant arrays were investigated. The possibilities, which arise by the exploitation of the real part of the refractive index in neutron imaging, were demonstrated in experiments with especially designed test samples and in measurements with ordinary, industrial components. (orig.)

  16. Beryllium Target for Accelerator - Based Boron Neutron Capture Therapy

    International Nuclear Information System (INIS)

    This work is part of a project for developing Accelerator Based Boron Neutron Capture Therapy (AB- BNCT) for which the generation of neutrons through nuclear reactions like 9Be(d,n) is necessary. In this paper first results of the design and development of such neutron production targets are presented. For this purpose, the neutron production target has to be able to withstand the mechanical and thermal stresses produced by intense beams of deuterons (of 1.4 MeV with a total current of about 30mA). In particular, the target should be able to dissipate an energy density of up to 1 kW/cm2 and preserve its physical and mechanical properties for a sufficient length of time under irradiation conditions and hydrogen damage. The target is proposed to consist of a thin Be deposit (neutron producing material) on a thin W or Mo layer to stop the beam and a Cu backing to help carry away the heat load. To achieve the adhesion of the Be films on W, Mo and Cu substrates, a powder blasting technique was applied with quartz and alumina microspheres. On the other hand, Ag deposits were made on some of the substrates previously blasted to favor the chemical affinity between Beryllium and the substrate thus improving adhesion. Be deposits were characterized by means of different techniques including Electron Microscopy (Sem) and Xr Diffraction. Roughness and thickness measurements were also made. To satisfy the power dissipation requirements for the neutron production target, a microchannel system model is proposed. The simulation based on this model permits to determine the geometric parameters of the prototype complying with the requirements of a microchannel system. Results were compared with those in several publications and discrepancies lower than 10% were found in all cases. A prototype for model validation is designed here for which simulations of fluid and structural mechanics were carried out and discussed

  17. Review on Desing Beam Shaping Assembly Based on the D-T Reaction for BNCT

    International Nuclear Information System (INIS)

    Boron Neutron Capture Therapy (BNCT) can be achieved using a compact high energy neutron generator, in which the neutron energy should be in the epithermal range (1 eV < E < 10 keV) with high epithermal flux for treating Glioblastoma Multiforme (GBM). For this purpose, a suitable Beam Shaping Assembly (BSA) of a D-T neutron source is required. A major advantage of a D-T neutron source is the low energy required for the deuteron beam, namely 400 keV. The BSA design consists of a neutron multiplier, a moderator, a reflector, a fast neutron filter, a thermal neutron filter, gamma shielding and a collimator. In this work, the simulation code MCNP-4C is used to simulate the suggested BSA design as given in the literature. Beam parameters obtained by the proposed BSA design for the D-T neutron generator are investigated based on the IAEA recommendation. The results will be presented and discussed, which can provide an appropriate neutron beam for BNCT and suitable for planning in-hospital installations.

  18. Dosimetry of the low fouence fast neutron beams for boron neutron capture therapy

    International Nuclear Information System (INIS)

    For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, EIC-1 ion chambers manufactured by A-150 plastic and used IC-17M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was 5 cc per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and, there results were compared with measured results. The absorbed dose of fast neutron beams was 6.47 x 10-3 cGy per 1 MU at the 4 cm depth of the water phantom, which is assumed to be effective depth for BNCT. The magnitude of gamma contamination intermingled with fast neutron beams was 65.2±0.9% at the same depth. In the dose distribution according to the depth or water, the neutron dose decreased linearly and the gamma dose decreased exponentially as the depth was deepened. The factor expressed energy level, D20/DI0, of the total dose was 0.718. Through the direct measurement using the two ion chambers, which is made different wall materials, and computer calculation of isodose distribution using MCNP simulation method, we have found the dose characteristics of low fluence fast neutron beams. If the power supply and the target material, which generate high voltage and current, will be developed and gamma

  19. Design and techniques for fusion blanket neutronics experiments using an accelerator-based deuterium-tritium neutron source

    International Nuclear Information System (INIS)

    The experiments performed in the Japan Atomic Energy Research Institute/U.S. Department of Energy collaborative program on fusion blanket neutronics are designed with consideration of geometrical and material configurations. The general guide that is used to design the engineering-oriented neutronics experiment, which uses an accelerator-based 14-MeV neutron source, is discussed and compared with neutronics characteristics of the reactor models. Preparation of the experimental assembly, blanket materials, and the neutron source is described. A variety of techniques for measuring the nuclear parameters such as the tritium production rate are developed or introduced through the collaboration as a basis of the neutronics experiments. The features of these techniques are discussed with the experimental error and compared with each other. 25 refs., 15 figs., 4 tabs

  20. Microprocessor-based neutron counter for DIII-D

    International Nuclear Information System (INIS)

    The operating environment for the DIII-D tokamak places requirements on health safety neutron monitoring which differ from previous health safety monitoring used on Doublet III. The new operating environment requires monitoring to include neutrons generated during tokamak shots and neutrons generated during neutral beam conditioning. Since neutral beam conditioning is performed asynchronously to the tokamak operation, a system of continuous monitoring is required. The original method for monitoring neutrons was performed using the DIII-D diagnostic data computer system, since only shot-related information was necessary. To perform continuous monitoring, a separate microcomputer-based system was implemented. The system was designed to use an IBM PC AT interfacing the neutron detectors through a GPIB bus with a single CAMAC crate. The software was selected to perform multi-tasking utilizing the concurrent PC DOS operating system with all applications developed in the C language. The primary requirements included monitoring the neutrons continuously, ensuring that health safety limits were not exceeded, and prevention of further operation when a limit was approached. The purpose of this paper is three-fold. First, the system will be described in terms of the hardware configuration and the software methods used collecting, managing, and displaying the data. Included in the description will be the justifications and trade-offs on selecting the exact hardware and software used. Second, the problems encountered in implementation due to non-compatible hardware and software will be covered. This discussion will focus on problems which are difficult to anticipate without direct experience with the exact hardware and software configuration. Third, guidelines which can be used to prevent some of the compatibility problems that can occur will be discussed. 4 figs

  1. Development of a mini high efficiency neutron detector based on 6LiI (Eu) scintillator

    International Nuclear Information System (INIS)

    A mini neutron detector with the dimension of φ25 mm ×20 mm is developed based on a 6LiI( Eu) scintillator with a Hamamatsu S3590-08 photodiode. The detector was used to detect thermal neutrons from a paraffin shielded 252Cf neutron source and the detect efficiency to thermal neutron was calculated to be 95% with a resolution of thermal neutron peak about 16%. (authors)

  2. Gel dosimeters as useful dose and thermal-fluence detectors in Boron Neutron Capture Therapy (BNCT)

    International Nuclear Information System (INIS)

    The dosimetry method based on Fricke-Xylenol-Orange-infused gels in form of layers has shown noticeable potentiality for in-phantom or in-free-beam dose and thermal flux profiling and imaging in the high fluxes of thermal or epithermal neutrons utilised for boron neutron capture therapy (BNCT). Gel-dosimeters in form of layers give the possibility not only of obtaining spatial dose distributions but also of achieving measurements of each dose contribution in neutron fields. The discrimination of the various dose components is achieved by means of pixel-to-pixel manipulations of pairs of images obtained with gel-dosimeters having different isotopic composition. It is possible to place large dosimeters, detecting in such a way large dose images, because the layer geometry of dosimeters avoids sensitive variation of neutron transport due to the gel isotopic composition. Some results obtained after the last improvements of the method are reported. (Author)

  3. Gel dosimeters as useful dose and thermal-fluence detectors in Boron Neutron Capture Therapy (BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Valente, M. [Department of Physics of the University and INFN, Via Celoria 16, I-20133 Milan (Italy); Moss, R.L.; Daquino, G.G.; Nievaart, V.A. [Joint Research Centre, Institute for Energy, P.O. Box 2, NL-1755ZG Petten, The Netherlands (Netherlands); Mariani, M.; Vanossi, E. [Department of Nuclear Engineering of Polytechnic, CESNEF, Via Ponzio, 34/3 - I-20133 Milan (Italy); Carrara, M. [Medical Physics Department, National Cancer Institute, Via Venezian 1, I-20131, Milan (Italy)

    2006-07-01

    The dosimetry method based on Fricke-Xylenol-Orange-infused gels in form of layers has shown noticeable potentiality for in-phantom or in-free-beam dose and thermal flux profiling and imaging in the high fluxes of thermal or epithermal neutrons utilised for boron neutron capture therapy (BNCT). Gel-dosimeters in form of layers give the possibility not only of obtaining spatial dose distributions but also of achieving measurements of each dose contribution in neutron fields. The discrimination of the various dose components is achieved by means of pixel-to-pixel manipulations of pairs of images obtained with gel-dosimeters having different isotopic composition. It is possible to place large dosimeters, detecting in such a way large dose images, because the layer geometry of dosimeters avoids sensitive variation of neutron transport due to the gel isotopic composition. Some results obtained after the last improvements of the method are reported. (Author)

  4. Neutron method and apparatus for determining total cross-section

    International Nuclear Information System (INIS)

    This invention relates to the determination of the macroscopic neutron absorption cross section of the geological formation surrounding a borehole. The method comprises passing a logging sonde through the borehole while continuously irradiating the formation with neutrons. The radiation emanating from the formation is monitored to generate a first signal indicative of thermal neutrons and a second signal indicative of epithermal neutrons. Output signals are generated indicative of the spatial distribution of thermal and epithermal neutrons, and are combined to generate a signal representative of the macroscopic neutron absorption cross section of the formation. The apparatus comprises a logging sonde adapted for movement through the borehole and carrying a neutron source; detector means on the sonde for monitoring radiation emanating from the formation to generate signals indicative of thermal and epithermal neutrons; means for generating output signals indicative of the spatial distribution of thermal and epithermal neutrons; and means for combining the two output signals to generate a signal indicative of the macroscopic neutron absorption cross section of the material

  5. Simultaneous and integrated neutron-based techniques for material analysis of a metallic ancient flute

    Science.gov (United States)

    Festa, G.; Pietropaolo, A.; Grazzi, F.; Sutton, L. F.; Scherillo, A.; Bognetti, L.; Bini, A.; Barzagli, E.; Schooneveld, E.; Andreani, C.

    2013-09-01

    A metallic 19th century flute was studied by means of integrated and simultaneous neutron-based techniques: neutron diffraction, neutron radiative capture analysis and neutron radiography. This experiment follows benchmark measurements devoted to assessing the effectiveness of a multitask beamline concept for neutron-based investigation on materials. The aim of this study is to show the potential application of the approach using multiple and integrated neutron-based techniques for musical instruments. Such samples, in the broad scenario of cultural heritage, represent an exciting research field. They may represent an interesting link between different disciplines such as nuclear physics, metallurgy and acoustics.

  6. High-energy in-beam neutron measurements of metal-based shielding for accelerator-driven spallation neutron sources

    Science.gov (United States)

    DiJulio, D. D.; Cooper-Jensen, C. P.; Björgvinsdóttir, H.; Kokai, Z.; Bentley, P. M.

    2016-05-01

    Metal-based shielding plays an important role in the attenuation of harmful and unwanted radiation at an accelerator-driven spallation neutron source. At the European Spallation Source, currently under construction in Lund, Sweden, metal-based materials are planned to be used extensively as neutron guide substrates in addition to other shielding structures around neutron guides. The usage of metal-based materials in the vicinity of neutron guides however requires careful consideration in order to minimize potential background effects in a neutron instrument at the facility. Therefore, we have carried out a combined study involving high-energy neutron measurements and Monte Carlo simulations of metal-based shielding, both to validate the simulation methodology and also to investigate the benefits and drawbacks of different metal-based solutions. The measurements were carried out at The Svedberg Laboratory in Uppsala, Sweden, using a 174.1 MeV neutron beam and various thicknesses of aluminum-, iron-, and copper-based shielding blocks. The results were compared to geant4 simulations and revealed excellent agreement. Our combined study highlights the particular situations where one type of metal-based solution may be preferred over another.

  7. Advanced epithermal thorium reactor (AETR) physics

    International Nuclear Information System (INIS)

    The AETR concept is reviewed in reference to existing theory, nuclear parameters, and potential neutron economy. The effect of thorium resonance capture in graphite-moderate d systems with median absorption energies in the range from 0.10 to 100 keV have been studied. Narrow-resonance (NR) and wide-resonance (NRIA) formulations are used to obtain the temperature-dependent effective resonance integral of thorium rods which are expressed as equivalent multi-group cross-sections. The need for nuclear data in the intermediate energy range led to design and con- struction of a critical assembly. Nuclear design of this assembly emphasizes the importance of cross-section data and the theoretical interpretation of these experimental results, both pertinent to the design of an AETR. The accuracy of the analytical techniques has been demonstrated in the analysis of ZPR-III experimental results. Three heat-transfer configurations are compared using doubling time as an optimizing parameter. The effect of Pa233 and uranium-isotope s production on relative neutron economy, potential breeding ratios, and burn-up characteristics are evaluated in regard to the uncertainties in the nuclear cross-sections. (author)

  8. Characterization of a boron carbide-based polymer neutron sensor

    Science.gov (United States)

    Tan, Chuting; James, Robinson; Dong, Bin; Driver, M. Sky; Kelber, Jeffry A.; Downing, Greg; Cao, Lei R.

    2015-12-01

    Boron is used widely in thin-film solid-state devices for neutron detection. The film thickness and boron concentration are important parameters that relate to a device's detection efficiency and capacitance. Neutron depth profiling was used to determine the film thicknesses and boron-concentration profiles of boron carbide-based polymers grown by plasma enhanced chemical vapor deposition (PECVD) of ortho-carborane (1,2-B10C2H12), resulting in a pure boron carbide film, or of meta-carborane (1,7-B10C2H12) and pyridine (C5H5N), resulting in a pyridine composite film, or of pyrimidine (C4H4N2) resulting in a pure pyrimidine film. The pure boron carbide film had a uniform surface appearance and a constant thickness of 250 nm, whereas the thickness of the composite film was 250-350 nm, measured at three different locations. In the meta-carborane and pyridine composite film the boron concentration was found to increase with depth, which correlated with X-ray photoelectron spectroscopy (XPS)-derived atomic ratios. A proton peak from 14N (n,p)14C reaction was observed in the pure pyrimidine film, indicating an additional neutron sensitivity to nonthermal neutrons from the N atoms in the pyrimidine.

  9. The Kohuamuri siliceous sinter as a vector for epithermal mineralisation, Coromandel Volcanic Zone, New Zealand

    Science.gov (United States)

    Hamilton, Ayrton; Campbell, Kathleen; Rowland, Julie; Browne, Patrick

    2016-04-01

    The Kohuamuri siliceous sinter is the largest known fossil hot-spring system in the Hauraki Goldfield, a 200 × 40 km volcanic terrain with at least 50 adularia-illite epithermal deposits formed 16.3-5.6 Ma within the Coromandel Volcanic Zone, New Zealand. The sinter is associated with rhyolite and ignimbrite of the Whitianga Caldera (Miocene-Pliocene) and consists of two deposits, the Kohuamuri deposit itself, a large in situ outcrop (47,000 m2) and its associated sinter boulder field (4500 m2), and the Kaitoke deposit 900 m to the southwest, comprising boulders in a landslide situated on a normal fault. The well-preserved macroscopic and microscopic textures at Kohuamuri are similar to actively forming and ancient hot-spring deposits elsewhere, derived from deep circulating, magmatically heated, near-neutral pH alkali chloride fluids oversaturated in amorphous silica and that discharge at the Earth's surface at ≤100 °C. Lithofacies, petrography, mineralogy, as well as trace element concentrations of the Kohuamuri/Kaitoke deposits were used to locate likely palaeo-thermal conduits from the deep reservoir and to reconstruct the palaeoenvironmental setting of the siliceous sinter as an aid to assessing the economic potential of the ancient geothermal system. Both deposits contain the high-temperature (>75 °C) geyserite lithofacies, with the Kohuamuri deposit also exhibiting textures affiliated with cooler middle and distal sinter apron areas, as well as geothermally influenced marsh facies. Trace element analysis of sinter lithofacies revealed concentrations and zonations of Au, Ag, base metals (Pb, Cu, Zn) and pathfinder elements (As, Sb) associated with epithermal deposits, elevated in the proximal vent area, and providing evidence of possible Au and Ag ore mineralisation at depth. The methodology used in this study could be utilised globally to identify and assess as yet unidentified epithermal deposits.

  10. An IBM-PC based reactor neutronics analysis package

    International Nuclear Information System (INIS)

    The development of a comprehensive system of microcomputer-based codes suitable for neutronics and shielding analysis of nuclear reactors has been undertaken by EGandG Idaho, Inc., at the Idaho National Engineering Laboratory (INEL). This system has been designed for cross section generation, one-dimensional discrete-ordinates analysis, one- two- and three-dimensional diffusion theory analysis, and various other radiation transport applications of interest

  11. Scintillation neutron detectors based on solid-state photomultipliers and lightguides

    International Nuclear Information System (INIS)

    Neutron detectors based on scintillation screens ZnS(Ag)/LiF and solid-state photomultipliers have been developed. Lightguides are used to collect light. The application of a coincidence scheme provides a low dark count and a neutron detection efficiency as high as 70%. A scheme of x-y neutron detector based on wavelength shifting fibers is also proposed. Tests of the proposed versions of detectors in a neutron beam have shown their efficiency

  12. Scintillation neutron detectors based on solid-state photomultipliers and lightguides

    Energy Technology Data Exchange (ETDEWEB)

    Litvin, V. S., E-mail: vlitvin@inr.ru; Marin, V. N.; Karaevsky, S. K.; Trunov, D. N.; Axenov, S. N.; Stolyarov, A. A.; Sadykov, R. A. [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)

    2016-01-15

    Neutron detectors based on scintillation screens ZnS(Ag)/LiF and solid-state photomultipliers have been developed. Lightguides are used to collect light. The application of a coincidence scheme provides a low dark count and a neutron detection efficiency as high as 70%. A scheme of x-y neutron detector based on wavelength shifting fibers is also proposed. Tests of the proposed versions of detectors in a neutron beam have shown their efficiency.

  13. The sensitivity of the UKAEA criticality dosimeter to slow neutrons

    International Nuclear Information System (INIS)

    Improvements have been made in the determination of the thermal and epithermal neutron sensitivity of the thick gold foil combination of the UKAEA personnel criticality dosimeter which is used to measure the neutron leakage spectra from critical assemblies and reactors. Calculations are presented to enable incident and reflected components of the thermal fluence and the epithermal fluence per unit lethargy interval to be derived from β-ray measurements from each gold foil surface. Gold foils and criticality dosimeters have been exposed to reference neutron fluence rates to verify the calibration, and the uncertainties of the method are described both for these reference exposures and for exposures in typical criticality conditions. (author)

  14. Progress on the realization of a new GEM based neutron diagnostic concept for high flux neutron beams

    Science.gov (United States)

    Croci, G.; Rebai, M.; Cazzaniga, C.; Palma, M. Dalla; Grosso, G.; Muraro, A.; Murtas, F.; Claps, G.; Pasqualotto, R.; Cippo, E. Perelli; Tardocchi, M.; Tollin, M.; Cavenago, M.; Gorini, G.

    2014-08-01

    Fusion reactors will need high flux neutron detectors to diagnose the deuterium-deuterium and deuterium-tritium. A candidate detection technique is the Gas Electron Multiplier (GEM). New GEM based detectors are being developed for application to a neutral deuterium beam test facility. The proposed detection system is called Close-contact Neutron Emission Surface Mapping (CNESM). The diagnostic aims at providing the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. This is done by placing a detector in close contact, right behind the dump. CNESM uses nGEM detectors, i.e. GEM detectors equipped with a cathode that also serves as neutron-proton converter foil. After the realization and test of several small area prototypes, a full size prototype has been realized and tested with laboratory sources. Test on neutron beams are foreseen for the next months.

  15. New class of neutron detectors

    Energy Technology Data Exchange (ETDEWEB)

    Czirr, J.B.

    1997-09-01

    An optimized neutron scattering instrument design must include all significant components, including the detector. For example, useful beam intensity is limited by detector dead time; detector pixel size determines the optimum beam diameter, sample size, and sample to detector distance; and detector efficiency vs. wavelength determines the available energy range. As an example of the next generation of detectors that could affect overall instrumentation design, we will describe a new scintillator material that is potentially superior to currently available scintillators. We have grown and tested several small, single crystal scintillators based upon the general class of cerium-activated lithium lanthanide borates. The outstanding characteristic of these materials is the high scintillation efficiency-as much as five times that of Li-glass scintillators. This increase in light output permits the practical use of the exothermic B (n, alpha) reaction for low energy neutron detection. This reaction provides a four-fold increase in capture cross section relative to the Li (n, alpha) reaction, and the intriguing possibility of demanding a charged-particle/gamma ray coincidence to reduce background detection rates. These new materials will be useful in the thermal and epithermal energy ran at reactors and pulsed neutron sources.

  16. Neutron transport benchmark examples with web-based AGENT

    International Nuclear Information System (INIS)

    The AGENT (Arbitrary GEometry Neutron Transport) an open-architecture reactor modeling tool is deterministic neutron transport code for two- or three-dimensional heterogeneous neutronic design and analysis of the whole reactor cores regardless of geometry types and material configurations. The AGENT neutron transport methodology is applicable to all generations of nuclear power and research reactors. It combines three theories: (1) mathematical theory of R-functions that is used to generate real three-dimensional geometries of square or hexagonal heterogeneous geometries, (2) the x-y method of characteristics (MOC) used to solve isotropic neutron transport in non-homogenized 2D reactor slices, and (3) the one-dimensional diffusion theory or MOC theory used to couple the x-y and z neutron tracks through the transverse leakage and angular mesh-wise flux values. The R-function geometrical module allows a sequential building of the layers of geometry and automatic submeshing based on the network of geometric domain functions. The simplicity of geometry description and selection of parameters for accurate treatment of neutron propagation is achieved through the Boolean algebraic hierarchically organized simple primitives into complex domains (both being represented with corresponding domain functions). AGENT methodologies and numerical solutions are applicable in validating neutronic analysis for GenIV reactor designs while the effect of double heterogeneity in very high temperature reactors (VHTRs) is under development. The accuracy is comparable to Monte Carlo codes and is obtained by following neutron propagation through real geometrical domains that does not require homogenization or simplifications. The efficiency is maintained through set of acceleration techniques introduced at all important calculation levels. The flux solution incorporates power iteration with two different acceleration techniques: coarse mesh rebalancing (CMR) and coarse mesh finite difference

  17. Kriging analysis of uranium concentrations in Test Area C-74L, Eglin Air Force Base, Florida

    International Nuclear Information System (INIS)

    Soil samples from Test Area C-74L, Eglin Air Force Base, Florida, were analyzed for depleted uranium by instrumental epithermal neutron activation analysis. The sampling design used was a modified polar coordinate scheme. The resulting data were analyzed with a statistical procedure called kriging to obtain a contour map of concentration and a 95% confidence interval map. The majority of uranium remains in the center of the area near the target abutment

  18. Neutron imaging system for neutron tomography, radiography, and beam diagnostics

    International Nuclear Information System (INIS)

    A neutron imaging system (NIS) has been recently installed at the University of Texas TRIGA reactor facility. The imaging system establishes new capabilities for beam diagnostics at the Texas Cold Neutron Source (TCNS) for real-time neutron radiography (RTNR) and for neutron computed tomography (NCT) research. The NIS will also be used for other research projects. The system consists of two subsystems as follows: (1) Thomson 9-in. neutron image intensifier (NII) tube sensitive to cold, thermal, and epithermal neutrons, (2) image-processing unit consisting of vidicon camera, two high-resolution monitors, image enhancement and measurement processor, and video printer. The NIS is installed at the cold neutron beam of the TCNS for testing and cold neutron beam diagnostics

  19. PELAN - a transportable, neutron-based UXO identification technique

    International Nuclear Information System (INIS)

    An elemental characterization method is used to differentiate between inert projectiles and UXO's. This method identifies in a non-intrusive, nondestructive manner, the elemental composition of the projectile contents. Most major and minor chemical elements within the interrogated object (hydrogen, carbon, nitrogen, oxygen, fluorine, phosphorus, chlorine, arsenic, etc.) are identified and quantified. The method is based on PELAN - Pulsed Elemental Analysis with Neutrons. PELAN uses pulsed neutrons produced from a compact, sealed tube neutron generator. Using an automatic analysis computer program, the quantities of each major and minor chemical element are determined. A decision-making tree identifies the object by comparing its elemental composition with stored elemental composition libraries of substances that could be contained within the projectile. In a series of blind tests, PELAN was able to identify without failure, the contents of each shell placed in front of it. The PELAN probe does not need to be in contact with the interrogated projectile. If the object is buried, the interrogation can take place in situ provided the probe can be inserted a few centimeters from the object's surface. (author)

  20. Development of a thermal neutron detector based on scintillating fibers and silicon photomultipliers

    International Nuclear Information System (INIS)

    We propose a technique for thermal neutron detection, based on a 6Li converter placed in front of scintillating fibers readout by means of silicon photomultipliers. Such a technique allows building cheap and compact detectors and dosimeters, thus possibly opening new perspectives in terms of granular monitoring of neutron fluxes as well as space-resolved neutron detection.

  1. Laboratory of neutron activation analysis at the Nuclear Physics Institute ASCR, Řež

    Czech Academy of Sciences Publication Activity Database

    Kučera, Jan

    2011-01-01

    Roč. 21, č. 1 (2011), s. 30-35. ISSN 1061-9127 Institutional research plan: CEZ:AV0Z10480505 Keywords : Instrumental neutron activation analysis * epithermal neutron activation analysis * radiochemical neutron activation analysis * applications in science and technology Subject RIV: BG - Nuclear, Atomic and Molecular Physics , Colliders

  2. Archaeometry Applications of Cold Neutron Based Prompt Gamma Neutron Activation Analysis. Chapter 9

    International Nuclear Information System (INIS)

    Prompt gamma activation analysis (PGAA) is based on the detection of prompt gamma radiation following the capture of neutrons into the atomic nucleus. Since every atomic nucleus emits characteristic prompt gamma radiation, this method is suitable for multielemental (panorama) analysis. The PGAA method can be regarded as absolutely non-destructive, because of the relatively low intensity of the beam. The main focus of this project was on the research of ancient ceramics. Pottery production was one of the most important crafts of prehistoric communities. As the first aim of this project, pottery findings from Neolithic and later prehistoric sites in Hungary were investigated with PGAA. Compositions of local sediments, as potential raw material sources, were compared with those of pottery. As the second aim of the project, pottery fragments from the multiperiod site at Voers, in south-west Hungary, were analysed, together with clay from the surrounding areas. In a firing experiment, an attempt to reproduce the ancient production techniques was made. As a third aim of the project, PGAA was tested from a methodological point of view. The reliability of the method has been occasionally checked through parallel measurements of archaeological samples with instrumental neutron activation analysis and X ray fluorescence analysis as well. The authors took part in a proficiency test, organized by the IAEA, on a porcelain material. (author)

  3. The analysis of the imaging speed of the neutron digital radiography system based CCD

    International Nuclear Information System (INIS)

    The imaging speed is the main character of the neutron digital radiography system, and the calculating method of neutron digital radiography based CCD is put forward according to the characters of CCD and the principal of neutron digital radiography and optics. Then the imaging speed of neutron radiography system in SPRR-300 is calculated by the method. The experiment shows the counted value basically tallies with the measured value, then the calculating method is believable. (authors)

  4. An accelerator-based neutron microbeam system for studies of radiation effects

    OpenAIRE

    Xu, Yanping; Randers-Pehrson, Gerhard; Marino, Stephen A.; Bigelow, Alan W.; Akselrod, Mark S.; Sykora, Jeff G.; Brenner, David J.

    2010-01-01

    A novel neutron microbeam is being developed at the Radiological Research Accelerator Facility (RARAF) of Columbia University. The RARAF microbeam facility has been used for studies of radiation bystander effects in mammalian cells for many years. Now a prototype neutron microbeam is being developed that can be used for bystander effect studies. The neutron microbeam design here is based on the existing charged particle microbeam technology at the RARAF. The principle of the neutron microbeam...

  5. Development of a Fresnel lens for cold neutrons based on neutron refractive optics

    International Nuclear Information System (INIS)

    We have developed compound refractive lenses (CRLs) for cold neutrons, which are made of vitreous silica and have an effective potential of (90.1-2.7x10-4i) neV. In the case of compound refractive optics, neutron absorption by the material deteriorates lens performance. Thus, to prevent an increase in neutron absorption with increasing beam size, we have developed Fresnel lenses using the electrolytic in-process dressing grinding technique. The lens characteristics were carefully investigated with experimental and numerical simulation studies. The lenses functioned as a neutron focusing lens, and the focal length of 14 m was obtained with a 44-element series of the Fresnel lenses for 10 A neutrons. Moreover, good neutron transmission of 0.65 for 15 A neutrons was obtained due to the shape effect. According to comprehensive analysis of the obtained results, it is possible to realize a CRL for practical use by choosing a suitable lens shape and material

  6. Monte Carlo based weighting functions in neutron capture measurements

    International Nuclear Information System (INIS)

    To determine neutron capture cross sections using C6D6 detectors, the Pulse Height Weighting Technique (PHWT) is mostly applied. The weighting function depends from the response function of the detection system in use. Therefore, the quality of the data depends on the detector response used for the calculation of the weighting function. An experimental determination of the response of C6D6 detectors is not always straightforward. We determined the detector response and, hence, the weighting function from Monte Carlo simulations, using the MCNP 4C2 code. To obtain reliable results a big effort was made in preparing geometry input file describing the experimental conditions. To validate the results of the Monte Carlo simulations we performed several experiments at GELINA. First, we measured the C6D6 detector response for standard -sources and for selected resonances in the 206Pb(n,). These responses were compared with the one based on Monte Carlo simulations. The good agreement between experimental and simulated data confirms the reliability of the Monte Carlo simulations. As a second validation exercise, we also determined the normalization factor in Ag and Au sample of different composition and thickness and the neutron width of the 1.15 keV resonance in 5 Fe using samples of different compositions. The result of this validation exercise was that the photon transport and the coupling of the photon and neutron transport must be accounted for in the determination of the weighting function. Accurate weighting functions are required for capture reactions in nuclei where the gamma cascade differs strongly from resonance to resonance, and are extremely important for neutron data related to reactor technologies where Pb-isotopes play an important role. The Monte Carlo based weighting function have been used to deduce the capture yield of 206Pb between 3 and 620 keV and of 232Th between 5 and 150 keV. This method will also be used for the analysis of other neutron capture

  7. Compton suppression method and epithermal NAA in the determination of nutrients and heavy metals in Nigerian food and beverages

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Y.A., E-mail: yaahmed1@gmail.co [Reactor Engineering Section, Centre for Energy Research and Training, Ahmadu Bello University, Zaria (Nigeria); Nuclear Engineering Teaching Laboratory, University of Texas at Austin, Austin, TX 78758 (United States); Landsberger, S.; O' Kelly, D.J.; Braisted, J. [Nuclear Engineering Teaching Laboratory, University of Texas at Austin, Austin, TX 78758 (United States); Gabdo, H. [Physics Department, Federal College of Education, Yola (Nigeria); Ewa, I.O.B.; Umar, I.M.; Funtua, I.I. [Reactor Engineering Section, Centre for Energy Research and Training, Ahmadu Bello University, Zaria (Nigeria)

    2010-10-15

    We used in this study Compton suppression method and epithermal neutron activation analysis to determine the concentration of nutrients and heavy metals in Nigerian food and beverages. The work was performed at the University of Texas TRIGA Reactor by short, medium, and long irradiation protocols, using thermal flux of 1.4x10{sup 12} n cm{sup -2} s{sup -1} and epithermal flux of 1.4x10{sup 11} n cm{sup -2} s{sup -1}. Application of Compton suppression method has reduced interferences from Compton scattered photons thereby allowing easy evaluation of Na, Cl, Ca, Cu, Mn, Mg, Co, Cr, Rb, Fe, and Se. The epithermal NAA method has enabled determination of Cd, As, Ba, Sr, Br, I, and V with little turn-around time. Quality Control and Quality Assurance of the method was tested by analyzing four Standard Reference Materials (non-fat powdered milk, apple leaves, citrus leaves, and peach leaves) obtained from National Institute for Standards and Technology. Our results show that sorghum, millet, and maize have high values of Zn, Mn, Fe, low values of Cd, As, and Se. Powdered milks, rice, beans, and soybeans were found to have moderate amounts of all the elements. Tobacco recorded high content of Cd, Mn, and As, whereas tea, tsobo leaves, Baobab leaves, and okro seed have more As values than others. However, biscuits, macaroni, spaghetti, and noodles show lower concentrations of all the elements. The distribution of these nutrients and heavy metals in these food and beverages shows the need to fortify biscuits and pastas with micro and macro-nutrients and reduce the use of tobacco, tea, tsobo leaves, Baobab leaves, and Okro seed to avoid intake of heavy elements.

  8. Compton suppression method and epithermal NAA in the determination of nutrients and heavy metals in Nigerian food and beverages

    International Nuclear Information System (INIS)

    We used in this study Compton suppression method and epithermal neutron activation analysis to determine the concentration of nutrients and heavy metals in Nigerian food and beverages. The work was performed at the University of Texas TRIGA Reactor by short, medium, and long irradiation protocols, using thermal flux of 1.4x1012 n cm-2 s-1 and epithermal flux of 1.4x1011 n cm-2 s-1. Application of Compton suppression method has reduced interferences from Compton scattered photons thereby allowing easy evaluation of Na, Cl, Ca, Cu, Mn, Mg, Co, Cr, Rb, Fe, and Se. The epithermal NAA method has enabled determination of Cd, As, Ba, Sr, Br, I, and V with little turn-around time. Quality Control and Quality Assurance of the method was tested by analyzing four Standard Reference Materials (non-fat powdered milk, apple leaves, citrus leaves, and peach leaves) obtained from National Institute for Standards and Technology. Our results show that sorghum, millet, and maize have high values of Zn, Mn, Fe, low values of Cd, As, and Se. Powdered milks, rice, beans, and soybeans were found to have moderate amounts of all the elements. Tobacco recorded high content of Cd, Mn, and As, whereas tea, tsobo leaves, Baobab leaves, and okro seed have more As values than others. However, biscuits, macaroni, spaghetti, and noodles show lower concentrations of all the elements. The distribution of these nutrients and heavy metals in these food and beverages shows the need to fortify biscuits and pastas with micro and macro-nutrients and reduce the use of tobacco, tea, tsobo leaves, Baobab leaves, and Okro seed to avoid intake of heavy elements.

  9. An alternative approach to the determination of epithermal flux-shaping factor (α) for k0-NAA

    International Nuclear Information System (INIS)

    The deviation of the epithermal flux spectra at reactor irradiation channel from the 'ideal' 1/E-shape to the 'non-ideal' 1/E1+α has to be corrected when applying k0 standardization of the neutron activation analysis. Cadmium ratio method is one of the popular methods used in the determination of this deviation (flux-shaping) factor but the equations involved demand iteration or graphical solution. Interactive computer programs (in BASIC and C++) were developed in this study to ease the otherwise cumbersome and challenging method of solving the cadmium ratio equations. The programs developed were used in the determination of the epithermal flux-shaping factor (α) for inner irradiation channel 5 and outer irradiation channel 7 of the Ghana Research Reactor-1 by irradiating Gold and Zirconium foils with and without Cadmium cover. The programs were also used to reproduce results reported earlier for inner channel 1 and outer channel 7 of the same reactor as a test of performance. The results obtained are - 0.107 for inner channel 5, -0.1246 for inner channel 1, -0.0241 for outer channel 6 and - 0.173 for outer channel 7. This result suggests that the interactive and less- cumbersome iteration programs in this study can be adopted for the determination of epithermal flux-shaping factor (α) since the values obtained follow similar trends reported for low power research reactors and the programs were able to reproduce results reported for the earlier characterized channels of the same reactor. (author)

  10. Compton suppression method and epithermal NAA in the determination of nutrients and heavy metals in Nigerian food and beverages.

    Science.gov (United States)

    Ahmed, Y A; Landsberger, S; O'Kelly, D J; Braisted, J; Gabdo, H; Ewa, I O B; Umar, I M; Funtua, I I

    2010-10-01

    We used in this study Compton suppression method and epithermal neutron activation analysis to determine the concentration of nutrients and heavy metals in Nigerian food and beverages. The work was performed at the University of Texas TRIGA Reactor by short, medium, and long irradiation protocols, using thermal flux of 1.4x10(12)n cm(-2)s(-1) and epithermal flux of 1.4x10(11)n cm(-2)s(-1). Application of Compton suppression method has reduced interferences from Compton scattered photons thereby allowing easy evaluation of Na, Cl, Ca, Cu, Mn, Mg, Co, Cr, Rb, Fe, and Se. The epithermal NAA method has enabled determination of Cd, As, Ba, Sr, Br, I, and V with little turn-around time. Quality Control and Quality Assurance of the method was tested by analyzing four Standard Reference Materials (non-fat powdered milk, apple leaves, citrus leaves, and peach leaves) obtained from National Institute for Standards and Technology. Our results show that sorghum, millet, and maize have high values of Zn, Mn, Fe, low values of Cd, As, and Se. Powdered milks, rice, beans, and soybeans were found to have moderate amounts of all the elements. Tobacco recorded high content of Cd, Mn, and As, whereas tea, tsobo leaves, Baobab leaves, and okro seed have more As values than others. However, biscuits, macaroni, spaghetti, and noodles show lower concentrations of all the elements. The distribution of these nutrients and heavy metals in these food and beverages shows the need to fortify biscuits and pastas with micro and macro-nutrients and reduce the use of tobacco, tea, tsobo leaves, Baobab leaves, and Okro seed to avoid intake of heavy elements. PMID:20472451

  11. Design of a model for BSA to meet free beam parameters for BNCT based on multiplier system for D–T neutron source

    International Nuclear Information System (INIS)

    Highlights: ► The possibility of using natural uranium as a neutron multiplier for D–T neutron generator is examined. ► To optimize output neutron beam, a moderator/filter/reflector arrangement was designed. ► The MCNP4C code has been used for BSA optimization and other simulations. ► The results show that using this system the BNCT in-air recommended parameters are met. - Abstract: Extensive research has recently been carried out for the development of high-energy D–T neutron generators as neutron sources for BNCT. The energy of these high-energy neutrons must be reduced by designing a Beam Shaping Assembly (BSA) to make them usable for BNCT. However, the neutron flux decreases drastically as neutrons pass through different materials of BSA. Therefore, it is very important to find ways to treat the neutrons economically. In this paper the possibility of using natural uranium as a neutron multiplier is investigated in order to increase the number of neutrons emitted from D–T neutron generator. According to the simulations and performed calculations, a sphere containing natural uranium as neutron multiplier was used to increase the number of neutrons generated by the D–T neutron generator. The energy of fast neutrons that are generated by D–T fusion reaction and amplified by neutron multiplier system is decreased using proper materials as moderators and fast neutron filters in BSA. The gamma rays which are generated as a result of neutron interaction with moderators are removed from neutron spectrum using bismuth as the gamma filter. Also, a thermal neutron absorber omits undesired low-energy neutrons which lead to a high radiation dose for the skin and soft tissues. The results show that passing neutrons through such a BSA causes the establishment of free beam parameters yet the reduction of the output beam intensity is unavoidable. The neutron spectrum related to our BSA has a proper epithermal flux and the fast and thermal neutron fluxes are

  12. Neutrons against cancer

    Science.gov (United States)

    Dovbnya, A. N.; Kuplennikov, E. L.; Kandybey, S. S.; Krasiljnikov, V. V.

    2014-09-01

    The review is devoted to the analysis and generalization of the research carried out during recent years in industrially advanced countries on the use of fast, epithermal, and thermal neutrons for therapy of malignant tumors. Basic facilities for neutron production used for cancer treatment are presented. Optimal parameters of therapeutic beams are described. Techniques using neutrons of different energy regions are discussed. Results and medical treatment efficiency are given. Comparison of the current state of neutron therapy of tumors and alternative treatments with beams of protons and carbon ions has been conducted. Main attention is given to the possibility of the practical use of accumulated experience of application of neutron beams for cancer therapy.

  13. Design of neutron beams for boron neutron capture therapy in a fast reactor

    International Nuclear Information System (INIS)

    The BNCT (Boron Neutron Capture Therapy) technique makes use of thermal or epithermal neutrons to irradiate tumours previously loaded with 10B. Reactors are currently seen as a suitable neutron source for BNCT implementation, due to the high intensity of the flux they can provide. The TAPIRO reactor, that is located at the ENEA Casaccia Centre near Rome, is a low-power fast-flux research reactor that can be usefully employed for this application. In this work computer simulations were carried out on this reactor to obtain epithermal and thermal neutron beams for the application of BNCT in Italy in the framework of a specific research program. Comparisons with measurements are also reported. Using the MCNP-4B code, Monte Carlo calculations were carried out to determine the materials suitable for the design of the thermal and epithermal columns. Various arrangements of reflector and moderator materials have been investigated to achieve the desired experimental constraints. On the basis of these calculations, a thermal column was designed and installed in the TAPIRO reactor to perform preliminary experiments on small laboratory animals. For the planning of a therapy treatment of gliomas on larger size animals, several material configurations were investigated in the search for an optimal epithermal facility. The aim of the present study is to indicate how a fast research reactor can be successfully modified for generating neutron beams suitable for BNCT applications. (author)

  14. Evidence for rapid epithermal mineralization and coeval bimodal volcanism, Bruner Au-Ag property, NV USA

    Science.gov (United States)

    Baldwin, Dylan

    zonation of veins, suggest that a 400 m vertical section of the epithermal system is now exposed at surface. 40Ar/39Ar geochronology of 3 adularia and 4 volcanic samples identified a rhyolite unit that slightly predates ~16.34 Ma Au-Ag mineralization and mafic magmatism. The proposed timeline for deposit formation is: 21-20 Ma, eruption of locally derived rhyolitic flows; 16.62 Ma, development of new rhyolite flow-dome complex and meteoric-dominated geothermal circulation along N-S structural fabric driven by heat from rhyolite domes; ~16.34 Ma, emplacement of NW trending basalt dikes, followed by violent hydrothermal eruptions, eruption of tuffisite breccia dikes, and Au-Ag mineralization; <16.34 Ma, post-mineral rhyolitic volcanism and normal faulting; and <16 Ma to present, continued faulting and dismemberment of the mineral system. The close spatial and temporal association of veining with coeval volcanic units suggests that Au-Ag-S traveled along similar structure and may have been supplied from the same magma chamber. Deposition of Au and Ag from HS- complexes by boiling appears to have occurred rapidly following closely spaced violent magmatic/hydrothermal eruption events. On a deposit scale, a complex interplay of depth, proximity to dikes, and structural dilatency during Au-Ag stage fluid pulses controlled localization of economic mineralization, which can be highly variable over meter-scale distances. Bruner appears to belong to a small subset of mid-Miocene epithermal deposits in Nevada with low base metal contents and low to no Se, related to calc- alkaline rhyolite flow-dome complexes. Multiple lines of evidence document decoupled sourcing of Al-Si-K-O from Au-Ag-S, and suggest that mafic magmatic inputs to an active, but barren geothermal system were important in forming the Bruner low-sulfidation epithermal ore deposit.

  15. Nondestructive analysis of RA reactor fuel burnup, Program for burnup calculation base on relative yield of 106Ru, 134Cs and 137Cs in the irradiated fuel

    International Nuclear Information System (INIS)

    Burnup of low enriched metal uranium fuel of the RA reactor is described by two chain reactions. Energy balance and material changes in the fuel are described by systems of differential equations. Numerical integration of these equations is base on the the reactor operation data. Neutron flux and percent of Uranium-235 or more frequently yield of epithermal neutrons in the neutron flux, is determined by iteration from the measured contents of 106Ru, 134Cs and 137Cs in the irradiated fuel. The computer program was written in FORTRAN-IV. Burnup is calculated by using the measured activities of fission products. Burnup results are absolute values

  16. Boron Neutron Capture Therapy at European research reactors - Status and perspectives

    International Nuclear Information System (INIS)

    Over the last decade. there has been a significant revival in the development of Boron Neutron Capture Therapy (BNCT) as a treatment modality for curing cancerous tumours, especially glioblastoma multiforme and subcutaneous malignant melanoma. In 1987 a European Collaboration on BNCT was formed, with the prime task to identify suitable research reactors in Europe where BNCT could be applied. Due to reasons discussed in this paper, the HFR Petten was chosen as the test-bed for demonstrating BNCT. Currently, the European Collaboration is approaching the start of clinical trials, using epithermal neutrons and borocaptate sodium (BSH) as the 10B delivery agent. The treatment is planned to start in the first half of 1996. The paper here presents an overview on the principle of BNCT, the requirements imposed on a research reactor in order to be considered for BNCT, and the perspectives for other European materials testing reactors. A brief summary on the current status of the work at Petten is given, including: the design, construction and characterisation of the epithermal neutron beam: performance and results of the healthy tissue tolerance study; the development of a treatment planning programme based on the Monte Carlo code MCNP; the design of an irradiation room; and on the clinical trials themselves. (author)

  17. Moderation of Neutrons Emitted by a Pulsed Source and Neutron Spectrometry Based on Slowing-Down Time

    International Nuclear Information System (INIS)

    Over the past ten years research has been going on at the P.N. Lebedev Physics Institute on the non-stationary moderation of neutrons in heavy media, the development of a method of neutron spectrometry based on the slowing-down time and the use of this method in studying the energy dependence of the cross-sections of nuclear reactions produced by neutrons with energy up to 30 keV. The authors review this work and discuss the results achieved. After a brief discussion of the theory of the non-stationary moderation and thermalization of neutrons the authors set forth the results of experimental studies of neutron moderation in graphite, iron and lead, and of neutron thermalization in lead. Using a pulsed neutron source and resonance detectors the distribution of slowing-down times was measured up to a series of fixed values for final neutron energy. The results are compared with theory, which takes into account the thermal motion of the moderator atoms; in the case of lead this thermal motion leads to a measurable spread in the slowing-down times at energies below 10 eV. The relationship between the mean velocity of neutrons in lead and the slowing-down time is measured in the subcadmium energy range and a comparison made with multigroup theory. The procedure for determining the energy dependence of neutron reaction cross-sections by slowing-down time is described and the potentialities of this method of spectrometry discussed. There follows a brief discussion of the results obtained in two fields of spectrometric measurement. Firstly, precise measurement of the relative excitation functions of the following reactions: He3(n, p), Li6(n, α), B10(n, α) and N14(n, p) - the most interesting results being the discovery of a constant negative component of the reaction cross-section and indications of the existence of an excited He4 level. Secondly, measurement of the energy dependence of averaged radiative capture cross-sections. Measurements carried out on a large

  18. Optimisation of resolution in accelerator-based fast neutron radiography

    CERN Document Server

    Rahmanian, H; Watterson, J I W

    2002-01-01

    In fast neutron radiography, imaging geometry, neutron scattering, the fast neutron scintillator and the position-sensitive detector all influence feature contrast, resolution and the signal-to-noise ratio in the image. The effect of imaging geometry can be explored by using a ray-tracing method. This requires following the path of neutrons through the imaging field, which includes the sample of interest. A relationship between imaging geometry and feature detectability can be developed. Monte Carlo methods can be used to explore the effect of neutron scattering on the results obtained with the ray-tracing technique. Fast neutrons are detected indirectly via neutron-nucleon scattering reactions. Using hydrogen-rich scintillators and relying on the recoil protons to ionise the scintillator material is the most sensitive technique available. The efficiency, geometry and composition of these scintillators influence the detectability of features in fast neutron radiography. These scintillator properties have a di...

  19. Influence of the epithermal effects on the MCF steady state

    International Nuclear Information System (INIS)

    This work is devoted to the correct interpretation of the steady-state parameters of the muon catalyzed fusion (MCF) process in a D/T mixture. Previously the influence of the epithermal effects (dtμ-molecule formation by 'hot', non-thermalized tμ atoms) on the steady-state parameters was studied only for measurements with a low-density target (density φ=0.01 relative to the liquid hydrogen density). We suggest a new method allowing direct determination of the necessary corrections to the MCF cycling rate for high-density data (φ≥0.4)

  20. Tagged neutron inspection system (TNIS) based on portable sealed generators

    International Nuclear Information System (INIS)

    A prototype of portable sealed neutron generator has been recently built to deliver 14 MeV neutron beams tagged by a YAP:Ce α-particle detector. In order to produce simultaneously multiple neutron beams to irradiate complex samples, a study of the position sensitivity of the α-particle detector has been performed. Possible applications in non-destructive analysis and future developments of the tagged neutron inspection system (TNIS) concept are discussed

  1. Novel Boron-10-based detectors for Neutron Scattering Science

    OpenAIRE

    Piscitelli, Francesco; project, for the ILL/ESS/LiU collaboration for the development of the B10 detector technology in the framework of the CRISP

    2015-01-01

    Nowadays neutron scattering science is increasing its instrumental power. Most of the neutron sources in the world are pushing the development of their technologies to be more performing. The neutron scattering development is also pushed by the European Spallation Source (ESS) in Sweden, a neutron facility which has just started construction. Concerning small area detectors (1m^2), the 3He technology, which is today cutting edge, is reaching fundamental limits in its development. Counting rat...

  2. Neutron Imaging Developments at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Ronald Owen [Los Alamos National Laboratory; Hunter, James F. [Los Alamos National Laboratory; Schirato, Richard C. [Los Alamos National Laboratory; Vogel, Sven C. [Los Alamos National Laboratory; Swift, Alicia L. [Los Alamos National Laboratory; Ickes, Timothy Lee [Los Alamos National Laboratory; Ward, William Carl [Los Alamos National Laboratory; Losko, Adrian Simon [University of California at Berkeley; Tremsin, Anton [University of California at Berkeley; Sevanto, Sanna Annika [Los Alamos National Laboratory; Espy, Michelle A. [Los Alamos National Laboratory; Dickman, Lee Thoresen [Los Alamos National Laboratory; Malone, Michael [Los Alamos National Laboratory

    2015-10-29

    Thermal, epithermal, and high-energy neutrons are available from two spallation sources at the 800 MeV proton accelerator. Improvements in detectors and computing have enabled new capabilities that use the pulsed beam properties at LANSCE; these include amorphous Si (aSi) detectors, intensified charge-coupled device cameras, and micro-channel plates. Applications include water flow in living specimens, inclusions and fission products in uranium oxide, and high-energy neutron imaging using an aSi flat panel with ZnS(Ag) scintillator screen. images of a metal/plastic cylinder from photons, low-energy and high-energy neutrons are compared.

  3. Transparent plastic scintillators for neutron detection based on lithium salicylate

    Science.gov (United States)

    Mabe, Andrew N.; Glenn, Andrew M.; Carman, M. Leslie; Zaitseva, Natalia P.; Payne, Stephen A.

    2016-01-01

    Transparent plastic scintillators with pulse shape discrimination containing 6Li salicylate have been synthesized by bulk polymerization with a maximum 6Li loading of 0.40 wt%. Photoluminescence and scintillation responses to gamma-rays and neutrons are reported herein. Plastics containing 6Li salicylate exhibit higher light yields and permit a higher loading of 6Li as compared to previously reported plastics based on lithium 3-phenylsalicylate. However, pulse shape discrimination performance is reduced in lithium salicylate plastics due to the requirement of adding more nonaromatic monomers to the polymer matrix as compared to those based on lithium 3-phenylsalicylate. Reduction in light yield and pulse shape discrimination performance in lithium-loaded plastics as compared to pulse shape discrimination plastics without lithium is interpreted in terms of energy transfer interference by the aromatic lithium salts.

  4. The variations of neutron component of lunar radiation background from LEND/LRO observations

    Science.gov (United States)

    Litvak, M. L.; Mitrofanov, I. G.; Sanin, A. B.; Bakhtin, B. N.; Bodnarik, J. G.; Boynton, W. V.; Chin, G.; Evans, L. G.; Harshman, K.; Livengood, T. A.; Malakhov, A.; Mokrousov, M. I.; McClanahan, Т. P.; Sagdeev, R.; Starr, R.

    2016-03-01

    Lunar neutron flux data measured by the Lunar Exploration Neutron Detector (LEND) onboard NASA's Lunar Reconnaissance Orbiter (LRO) were analyzed for the period 2009-2014. We have re-evaluated the instrument's collimation capability and re-estimated the neutron counting rate measured in the Field of View (FOV) of the LEND collimated detectors, and found it to be 1.0±0.1 counts per second. We derived the spectral density of the neutron flux for various lunar regions using our comprehensive numerical model of orbital measurements. This model takes into account the location of the LEND instrument onboard LRO to calculate the surface leakage neutron flux and its propagation to the instrument detectors. Based on this we have determined the lunar neutron flux at the surface to be ~2 neutrons/[cm2 sec] in the epithermal energy range, 0.4 eV to 1 keV. We have also found variations of the lunar neutron leakage flux with amplitude as large as a factor of two, by using multi-year observations to explore variations in the Galactic Cosmic Ray (GCR) flux during the 23rd-24th solar cycles.

  5. A dosimetry study of deuterium-deuterium neutron generator-based in vivo neutron activation analysis

    Science.gov (United States)

    Sowers, Daniel A.

    A neutron irradiation cavity for in vivo Neutron Activation Analysis (IVNAA) to detect manganese, aluminum, and other potentially toxic elements in human hand bone has been designed and its dosimetric specifications measured. The neutron source is a customized deuterium-deuterium neutron generator which produces neutrons at 2.45 MeV by the fusion reaction 2H(d, n)3He at a calculated flux of 7 x 108 +/-30% s-1. A moderator/reflector/shielding (5 cm high density polyethylene (HDPE), 5.3 cm graphite & 5.7 cm borated HDPE) assembly has been designed and built to maximize the thermal neutron flux inside the hand irradiation cavity and to reduce the extremity dose and effective dose to the human subject. Lead sheets are used to attenuate bremsstrahlung x rays and activation gammas. A Monte Carlo simulation (MCNP6) was used to model the system and calculate extremity dose. The extremity dose was measured with neutron and photon sensitive film badges and Fuji electronic pocket dosimeter (EPD). The neutron ambient dose outside the shielding was measured by Fuji NSN3, and photon dose by a Bicron MicroREM scintillator. Neutron extremity dose was calculated to be 32.3 mSv using MCNP6 simulations given a 10 min IVNAA measurement of manganese. Measurements by EPD and film badge indicate hand dose to be 31.7 +/- 0.8 mSv for neutron and 4.2 +/- 0.2 mSv for photon for 10 mins; whole body effective dose was calculated conservatively to be 0.052 mSv. Experimental values closely match values obtained from MCNP6 simulations. These are acceptable doses to apply the technology for a manganese toxicity study in a human population.

  6. Study of a nTHGEM-based thermal neutron detector

    Science.gov (United States)

    Li, Ke; Zhou, Jian-Rong; Wang, Xiao-Dong; Xiong, Tao; Zhang, Ying; Xie, Yu-Guang; Zhou, Liang; Xu, Hong; Yang, Gui-An; Wang, Yan-Feng; Wang, Yan; Wu, Jin-Jie; Sun, Zhi-Jia; Hu, Bi-Tao

    2016-07-01

    With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in 3He gas supply, research on new types of neutron detector as an alternative to 3He is a research hotspot in the field of particle detection. GEM (Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors. In this paper, the physical process of neutron detection is simulated with Geant4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic nTHGEM (neutron THick GEM) for neutron detection. The performance of the nTHGEM working in different Ar/CO2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. A detector with a single nTHGEM has been tested for 2-D imaging using a 252Cf neutron source. The key parameters of the performance of the nTHGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector. Supported by National Natural Science Foundation of China (11127508, 11175199, 11205253, 11405191), Key Laboratory of Neutron Physics, CAEP (2013DB06, 2013BB04) and CAS (YZ201512)

  7. Kriging-based algorithm for nuclear reactor neutronic design optimization

    International Nuclear Information System (INIS)

    Highlights: ► A Kriging-based algorithm was selected to guide research reactor optimization. ► We examined impacts of parameter values upon the algorithm. ► The best parameter values were incorporated into a set of best practices. ► Algorithm with best practices used to optimize thermal flux of concept. ► Final design produces thermal flux 30% higher than other 5 MW reactors. - Abstract: Kriging, a geospatial interpolation technique, has been used in the present work to drive a search-and-optimization algorithm which produces the optimum geometric parameters for a 5 MW research reactor design. The technique has been demonstrated to produce an optimal neutronic solution after a relatively small number of core calculations. It has additionally been successful in producing a design which significantly improves thermal neutron fluxes by 30% over existing reactors of the same power rating. Best practices for use of this algorithm in reactor design were identified and indicated the importance of selecting proper correlation functions.

  8. Neutron detector based on lithiated sol-gel glass

    CERN Document Server

    Wallace, S; Miller, L F; Dai, S

    2002-01-01

    A neutron detector technology is demonstrated based on sup 6 Li/ sup 1 sup 0 B doped sol-gel glass. The detector is a sol-gel glass film coated silicon surface barrier detector (SBD). The ionized charged particles from (n, alpha) reactions in the sol-gel film enter the SBD and are counted. Data showing that gamma-ray pulse amplitudes interfere with identifying charged particles that exit the film layer with energies below the gamma-ray energy is presented. Experiments were performed showing the effect of sup 1 sup 3 sup 7 Cs and sup 6 sup 0 Co gamma rays on the SBD detector. The reaction product energies of the triton and alpha particles from sup 6 Li are significantly greater than the energies of the Compton electrons from high-energy gamma rays, allowing the measurement of neutrons in a high gamma background. The sol-gel radiation detection technology may be applicable to the characterization of transuranic waste, spent nuclear fuel and to the monitoring of stored plutonium.

  9. Numerical analysis of the neutron distribution for a 14 MeV pulsed source in a two-layer infinite cylindrical medium

    International Nuclear Information System (INIS)

    Energy and time distributions for neutron flux in the task of pulse neutron-neutron logging have been numerically obtained by the Monte-Carlo method. The task geometry: an infinite stratum (SiO2 with 2x65 g/cm3 density and volume moisture content m) is crossed by an infinite cylinder of 9.85 cm radius (the cylinder is filled with water). A neutron source is pulse, isotropic monoenergetic (14 MeV) point. A model of neutron interaction with a substance is created on the base of ENDL data library. Neutron flux is calculated in spheres of 2 cm radius probes at 0 and 10 cm for six energy ranges. 0-10-3 time scale is divided in such a way that it can be possible to determine maxima of time flux distributions. Time distributions have been obtained for centric and eccentric positions of the ''source-sphere center'' axis. Effect of stratum moisture content on time distribution of neutron flux within the energy range of 0.215-100 eV has been investigated. Calculational procedure to obtain analogous distributions on 20 and 30 cm probes has been evaluated. It is underlined that the time range from 1x10-5 to 5x10-5s can be used to determine stratum humidity at volume moisture content m>=0.2; at m<0.2 ranges with a greater time value must be used. General analysis of nature of epithermal neutron time spectrum shows that for the stratum crossed by a well epithermal neutron flux stops suddenly at a time t the ''stopping'' time increases with decreasing m and displacing the instrument from the well axis

  10. Development of a Fresnel lens for cold neutrons based on neutron refractive optics

    CERN Document Server

    Oku, T; Moriyasu, S; Yamagata, Y; Ohmori, H; Takizawa, Y; Shimizu, H M; Hirota, T; Kiyanagi, Y; Ino, T; Furusaka, M; Suzuki, J

    2001-01-01

    We have developed compound refractive lenses (CRLs) for cold neutrons, which are made of vitreous silica and have an effective potential of (90.1-2.7x10 sup - sup 4 i) neV. In the case of compound refractive optics, neutron absorption by the material deteriorates lens performance. Thus, to prevent an increase in neutron absorption with increasing beam size, we have developed Fresnel lenses using the electrolytic in-process dressing grinding technique. The lens characteristics were carefully investigated with experimental and numerical simulation studies. The lenses functioned as a neutron focusing lens, and the focal length of 14 m was obtained with a 44-element series of the Fresnel lenses for 10 A neutrons. Moreover, good neutron transmission of 0.65 for 15 A neutrons was obtained due to the shape effect. According to comprehensive analysis of the obtained results, it is possible to realize a CRL for practical use by choosing a suitable lens shape and material.

  11. Expectation for energy selective neutron source based on the current neutron irradiation study of materials

    International Nuclear Information System (INIS)

    For an effective utilization of superior characteristics of the energy selective high energy neutron source, a consideration was made. Electron irradiation with high voltage electron microscopes (HVEM), D-T fusion neutron irradiation with rotating target neutron source (RTNS-II), and fission neutron irradiation with fission reactors were referred. The expected Energy Selective Neutron Source (ESNS) were compared with different types of irradiation facilities in regard to energy spectrum, flux stability, temperature control, and possibility of in-situ experiments. The excellent performance of HVEM electron irradiation, and of RTNS-II D-T fusion neutron irradiation was exemplified. The possibility of extending these excellent performances to the future ESNS experiment was discussed. Difficulties in the neutron irradiation experiment with fission reactors were exemplified. Shrinkage and growth of these difficulties in the ESNS experiment was discussed. Expected advantage and limitation of the ESNS was evaluated. Finally the positioning of ESNS was made, and the importance of its complementality with other facilities was pointed out. (M.T.)

  12. Optimization study of a transportable neutron radiography unit based on a compact neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Fantidis, J.G. [Laboratory of Nuclear Technology, School of Engineering, ' Democritus' University of Thrace, Xanthi (Greece); Nicolaou, G.E., E-mail: nicolaou@ee.duth.g [Laboratory of Nuclear Technology, School of Engineering, ' Democritus' University of Thrace, Xanthi (Greece); Tsagas, N.F. [Laboratory of Nuclear Technology, School of Engineering, ' Democritus' University of Thrace, Xanthi (Greece)

    2010-06-21

    A transportable fast and thermal neutron radiography system, incorporating a compact DD neutron generator, has been simulated using the MCNPX code. The materials considered were compatible with the European Union Directive on 'Restriction of Hazardous Substances'(RoHS) 2002/95/EC, hence excluding the use of cadmium and lead. Appropriate collimators were simulated for each of the radiography modes. With suitable aperture and collimator designs, it was possible to optimize the parameters for both fast and thermal neutron radiographies, for a wide range of values of the collimator ratio. The system simulated allows different object sizes to be studied with a wide range of radiography parameters.

  13. Optimization study of a transportable neutron radiography unit based on a compact neutron generator

    International Nuclear Information System (INIS)

    A transportable fast and thermal neutron radiography system, incorporating a compact DD neutron generator, has been simulated using the MCNPX code. The materials considered were compatible with the European Union Directive on 'Restriction of Hazardous Substances'(RoHS) 2002/95/EC, hence excluding the use of cadmium and lead. Appropriate collimators were simulated for each of the radiography modes. With suitable aperture and collimator designs, it was possible to optimize the parameters for both fast and thermal neutron radiographies, for a wide range of values of the collimator ratio. The system simulated allows different object sizes to be studied with a wide range of radiography parameters.

  14. An algorithm for computing thick target differential p-Li neutron yields near threshold

    International Nuclear Information System (INIS)

    The 7Li(p,n)7Be reaction is a good source of neutrons for accelerator boron neutron capture therapy (BNCT). Both reactor and accelerator neutron sources produce fast neutrons, which must be moderated since BNCT uses epithermal neutrons. Near-threshold BNCT uses proton energies only tens of keV above the reaction threshold, which reduces the thick target neutron yield but also produces neutrons closer to epithermal energies, so that less moderation is required. Accurate methods for calculating near-threshold differential neutron yields from thick targets of lithium, as well as certain low weight lithium compounds, were developed for BNCT source design. Neutron yields for proton beams up to 2.8 MeV will be presented. Good agreement with yields from several targets will be demonstrated. copyright 1999 American Institute of Physics

  15. Study on the response of indigenously developed CaSO4:Dy phosphor based neutron dosemeter

    International Nuclear Information System (INIS)

    In the present paper we report indigenous development of a neutron sensitive thermoluminescent (TL) dosemeter based on CaSO4:Dy Teflon TL disc. For large scale neutron monitoring of about 15,000 workers, engaged in the nuclear fuel cycle operation, the new dosemeter can be easily incorporated in the present TLD badge system used in personnel monitoring in our country just by a small change in the designing of the badge cassette. The study includes indigenous development of neutron dosemeter, response of the neutron dosemeter in terms of operational quantity to different energies of neutrons under various irradiation conditions. It was found that the thermal neutron sensitivity of the CaSO4:Dy Teflon neutron disc is about one third of TLD-600. However the thermal neutron sensitivity with respect to CaSO4:Dy Teflon gamma disc is about 42 times for in air irradiation and about 84 times for on-phantom irradiation conditions. This newly developed neutron disc can be used as a routine TL dosemeter in the mixed fields of gamma and neutron for neutron energy upto 500 keV for radiation workers engaged in nuclear fuel cycle operation. (author)

  16. Investigation of ancient pottery from Lefkanti, Greece, by epithermal gamma spectroscopy using loss-free counting technology

    International Nuclear Information System (INIS)

    For the analysis of pottery fragments from ancient Lefkanti, instrumental neutron activation analysis was used. To have a good throughput of samples, a detectable series of short-lived isotopes was selected for the investigation. The problem of the initial high radioactivity, which normally hinders a fast γ-spectroscopic analysis, was eluded by using loss-free counting technology. This technology allows the measurement of pottery samples of about 100 mg size 1 day after a 30 min epithermal irradiation. Up to 15 samples could be analyzed in one day under these working conditions, having the possibility to analyze the elements As, Eu, Ga, Gd, La, Mn, Sb, Sm, Th, U, W and Zn, which are enough to perform statistical characterizations of potteries. (author). 11 refs., 2 figs., 1 tab

  17. IBM-PC based reactor neutronics analysis package

    International Nuclear Information System (INIS)

    The development of a comprehensive system of microcomputer-based codes suitable for neutronics and shielding analysis of nuclear reactors has been undertaken by EG and G Idaho, Inc. at the Idaho National Engineering Laboratory (INEL). This system has been designed for cross section generation, one-dimensional discrete-ordinates analysis, one- two- and three-dimensional diffusion theory analysis, and various other radiation transport applications of interest. Several code modules are now operational, others are still under development. Use of desktop microcomputers rather than mainframe systems for complex scientific calculations offers several distinct advantages. These include economy, user convenience, and local, decentralized control of calculations. In addition to INEL applications, this code system could be extremely useful outside of the National Laboratory environment where access to appropriate mainframe computing systems may be limited. Outside users may include universities and some utilities and consultant organizations

  18. Archaeometry Applications of Cold Neutron Based Prompt Gamma Neutron Activation Analysis

    International Nuclear Information System (INIS)

    Prompt Gamma Activation Analysis (PGAA) is based on the detection of prompt gamma radiation following the capture of the neutrons into the atomic nucleus. Since every atomic nucleus emits characteristic prompt gamma radiation, this method is suitable for multielemental (panorama) analysis. The PGAA method can be regarded absolutely non-destructive, because of the relatively low intensity of the beam. In this project, we mainly focus on the research of ancient ceramics. Pottery production is one of the most important crafts of prehistoric communities. In the first task, pottery findings from Neolithic later prehistoric sites in Hungary were investigated with PGAA. Compositions of local sediments, as potential raw material sources were compared with those of pottery. In the second task, pottery fragments from the multiperiodical site of Voers, SW-Hungary were analyzed together with clay from the surrounding areas. In a firing experiment, an attempt to reproduce the ancient production techniques was done. As a third task of the project, PGAA was tested from methodological point of view. The reliability of the method has been occasionally checked through parallel measurements of archaeological samples with INAA and XRF as well. We took part in a proficiency test on a porcelane material, organized by IAEA. (author)

  19. Development and characterization of a neutron detector based on a lithium glass–polymer composite

    International Nuclear Information System (INIS)

    We report on the fabrication and characterization of a neutron scintillation detector based on a Li-glass–polymer composite that utilizes a combination of pulse height and pulse shape discrimination (PSD) to achieve high gamma rejection. In contrast to fast neutron detection in a PSD medium, we combine two scintillating materials that do not possess inherent neutron/gamma PSD properties to achieve effective PSD/pulse height discrimination in a composite material. Unlike recoil-based fast neutron detection, neutron/gamma discrimination can be robust even at low neutron energies due to the high Q-value neutron capture on 6Li. A cylindrical detector with a 5.05 cm diameter and 5.08 cm height was fabricated from scintillating 1 mm diameter Li-glass rods and scintillating polyvinyltoluene. The intrinsic efficiency for incident fission neutrons from 252Cf and gamma rejection of the detector were measured to be 0.33% and less than 10−8, respectively. These results demonstrate the high selectivity of the detector for neutrons and provide motivation for prototyping larger detectors optimized for specific applications, such as detection and event-by-event spectrometry of neutrons produced by fission

  20. Development and characterization of a neutron detector based on a lithium glass–polymer composite

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, M.; Nattress, J.; Kukharev, V.; Foster, A.; Meddeb, A. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Trivelpiece, C. [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Ounaies, Z. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Jovanovic, I., E-mail: ijovanovic@psu.edu [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2015-06-11

    We report on the fabrication and characterization of a neutron scintillation detector based on a Li-glass–polymer composite that utilizes a combination of pulse height and pulse shape discrimination (PSD) to achieve high gamma rejection. In contrast to fast neutron detection in a PSD medium, we combine two scintillating materials that do not possess inherent neutron/gamma PSD properties to achieve effective PSD/pulse height discrimination in a composite material. Unlike recoil-based fast neutron detection, neutron/gamma discrimination can be robust even at low neutron energies due to the high Q-value neutron capture on {sup 6}Li. A cylindrical detector with a 5.05 cm diameter and 5.08 cm height was fabricated from scintillating 1 mm diameter Li-glass rods and scintillating polyvinyltoluene. The intrinsic efficiency for incident fission neutrons from {sup 252}Cf and gamma rejection of the detector were measured to be 0.33% and less than 10{sup −8}, respectively. These results demonstrate the high selectivity of the detector for neutrons and provide motivation for prototyping larger detectors optimized for specific applications, such as detection and event-by-event spectrometry of neutrons produced by fission.

  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. Experimental research on the THGEM-based thermal neutron detector

    OpenAIRE

    Lei, Yang; Jian-Rong, Zhou; Zhi-Jia, Sun; Ying, Zhang; Chao-Qiang, Huang; Guang-Ai, Sun; Yan-feng, Wang; Gui-An, Yang; HONG, XU; Yu-Guang, Xie; Yuan-Bo, Chen

    2014-01-01

    A new thermal neutron detector with the domestically produced THGEM (THick Gas Electron Multiplier) was developed as an alternative to 3He to meet the needs of the next generation of neutron facilities. One type of Au-coated THGEM was designed specifically for the neutron detection. A detector prototype had been developed and the preliminary experimental tests were presented, including the performance of the Au-coated THGEM working in the Ar/CO2 gas mixtures and the neutron imaging test with ...

  3. Experimental research on the THGEM-based thermal neutron detector

    CERN Document Server

    Lei, Yang; Zhi-Jia, Sun; Ying, Zhang; Chao-Qiang, Huang; Guang-Ai, Sun; Yan-Feng, Wang; Gui-An, Yang; Hong, Xu; Yu-Guang, Xie; Yuan-Bo, Chen

    2014-01-01

    A new thermal neutron detector with the domestically produced THGEM (THick Gas Electron Multiplier) was developed as an alternative to 3He to meet the needs of the next generation of neutron facilities. One type of Au-coated THGEM was designed specifically for the neutron detection. A detector prototype had been developed and the preliminary experimental tests were presented, including the performance of the Au-coated THGEM working in the Ar/CO2 gas mixtures and the neutron imaging test with 252CF source, which would provide the reference of experimental data for the research in future.

  4. Two reports: (i) Correlation properties of delayed neutrons from fast neutron induced fission. (ii) Method and set-up for measurements of trace level content of heavy fissionable elements based on delayed neutron counting

    International Nuclear Information System (INIS)

    The document includes the following two reports: 'Correlation properties of delayed neutrons from fast neutron induced fission' and 'Method and set-up for measurements of trace level content of heavy fissionable elements based on delayed neutron counting. A separate abstract was prepared for each report

  5. Advanced spallation neutron sources for condensed matter research

    International Nuclear Information System (INIS)

    Advanced spallation neutron sources afford significant advantages over existing high flux reactors. The effective flux is much greater than that currently available with reactor sources. A ten-fold increase in neutron flux will be a major benefit to a wide range of condensed matter studies, and it will realise important experiments that are marginal at reactor sources. Moreover, the high intensity of epithermal neutrons open new vistas in studies of electronic states and molecular vibrations. (author)

  6. An accurate and portable solid state neutron rem meter

    International Nuclear Information System (INIS)

    Accurately resolving the ambient neutron dose equivalent spanning the thermal to 15 MeV energy range with a single configuration and lightweight instrument is desirable. This paper presents the design of a portable, high intrinsic efficiency, and accurate neutron rem meter whose energy-dependent response is electronically adjusted to a chosen neutron dose equivalent standard. The instrument may be classified as a moderating type neutron spectrometer, based on an adaptation to the classical Bonner sphere and position sensitive long counter, which, simultaneously counts thermalized neutrons by high thermal efficiency solid state neutron detectors. The use of multiple detectors and moderator arranged along an axis of symmetry (e.g., long axis of a cylinder) with known neutron-slowing properties allows for the construction of a linear combination of responses that approximate the ambient neutron dose equivalent. Variations on the detector configuration are investigated via Monte Carlo N-Particle simulations to minimize the total instrument mass while maintaining acceptable response accuracy—a dose error less than 15% for bare 252Cf, bare AmBe, an epi-thermal and mixed monoenergetic sources is found at less than 4.5 kg moderator mass in all studied cases. A comparison of the energy dependent dose equivalent response and resultant energy dependent dose equivalent error of the present dosimeter to commercially-available portable rem meters and the prior art are presented. Finally, the present design is assessed by comparison of the simulated output resulting from applications of several known neutron sources and dose rates

  7. Study on the imaging ability of the 2D neutron detector based on MWPC

    OpenAIRE

    LiChao, Tian; YuanBo, Chen; Bin, Tang; JianRong, Zhou; HuiRong, Qi; RongGuang, Liu; Zhang JIAN; GuiAn, Yang; HONG, XU; DongFeng, Chen; ZhiJia, Sun

    2013-01-01

    A 2D neutron detector based on 3He convertor and MWPC with an active area of 200 mm \\times 200 mm has been successfully designed and fabricated. The detector has been tested with Am/Be neutron source and with collimated neutron beam with wavelength of {\\lambda} = 1.37 {\\AA}. A best spatial resolution of 1.18 mm (FWHM) and good linearity were obtained. This is in good agreement with the theoretical calculations.

  8. Boron Neutron Capture Therapy at the TRIGA Mark II of Pavia, Italy - The BNCT of the diffuse tumours

    Energy Technology Data Exchange (ETDEWEB)

    Altieri, S.; Bortolussi, S.; Stella, S.; Bruschi, P.; Gadan, M.A. [University of Pavia (Italy); INFN - National Institute for Nuclear Physics, of Pavia (Italy)

    2008-10-29

    The selectivity based on the B distribution rather than on the irradiation field makes Boron neutron Capture Therapy (BNCT) a valid option for the treatment of the disseminated tumours. As the range of the high LET particles is shorter than a cell diameter, the normal cells around the tumour are not damaged by the reactions occurring in the tumoral cells. PAVIA 2001: first treatment of multiple hepatic metastases from colon ca by BNCT and auto-transplantation technique: TAOrMINA project. The liver was extracted after BPA infusion, irradiated in the Thermal Column of the Pavia TRIGA Mark II reactor, and re-implanted in the patient. Two patients were treated, demonstrating the feasibility of the therapy and the efficacy in destroying the tumoral nodules sparing the healthy tissues. In the last years, the possibility of applying BNCT to the lung tumours using epithermal collimated neutron beams and without explanting the organ, is being explored. The principal obtained results of the BNCT research are presented, with particular emphasis on the following aspects: a) the project of a new thermal column configuration to make the thermal neutron flux more uniform inside the explanted liver, b) the Monte Carlo study by means of the MCNP code of the thermal neutron flux distribution inside a patient's thorax irradiated with epithermal neutrons, and c) the measurement of the boron concentration in tissues by (n,{alpha}) spectroscopy and neutron autoradiography. The dose distribution in the thorax are simulated using MCNP and the anthropomorphic model ADAM. To have a good thermal flux distribution inside the lung epithermal neutrons must be used, which thermalize crossing the first tissue layers. Thermal neutrons do not penetrate and the obtained uniformity is poor. In the future, the construction of a PGNAA facility using a horizontal channel of the TRIGA Mark II is planned. With this method the B concentration can be measured also in liquid samples (blood, urine) and

  9. Measurement of angular distribution of neutron flux for the 6 MeV race-track microtron based pulsed neutron source

    International Nuclear Information System (INIS)

    The 6 MeV race track microtron based pulsed neutron source has been designed specifically for the elemental analysis of short lived activation products, where the low neutron flux requirement is desirable. Electrons impinges on a e-γ target to generate bremsstrahlung radiations, which further produces neutrons by photonuclear reaction in γ-n target. The optimisation of these targets along with their spectra were estimated using FLUKA code. The measurement of neutron flux was carried out by activation of vanadium at different scattering angles. Angular distribution of neutron flux indicates that the flux decreases with increase in the angle and are in good agreement with the FLUKA simulation.

  10. Gamma/neutron dose evaluation using Fricke gel and alanine gel dosimeters to be applied in boron neutron capture therapy

    International Nuclear Information System (INIS)

    Full text: Radiosurgery is a non-invasive surgery carried out by means of directed beams of ionizing radiation. This procedure was developed since there are many diseases for which conventional surgical treatment can not be applied, due to difficult or vital structures being damaged. Neutron radiation from nuclear reactors is used in a kind of radiosurgery called Boron Neutron Capture Therapy (BNCT) for the treatment of brain tumours which depends on the interaction of slow neutrons with 10B isotope injected in the tumour to produce alpha particles. Gel Dosimetry allows three-dimensional (3D) measurement of absorbed dose in tissueequivalent dosimeter phantoms. The measure technique is based on the transformation of ferrous ions (Fe2+) and ferric ions (Fe3+). The ferric ions concentration can be measured by spectrophotometry technique comparing the two wavelengths, 457 nm band that corresponds to ferrous ions concentration and 588 nm band that corresponds to ferric ions concentration. This work aims to study the gamma/neutron reactor dose relationship to be applied in BNCT using gel dosimeters. The Fricke Xylenol Gel (FXG) and Alanine Gel (AG) gel solutions produced at IPEN using gelatine 300 bloom were mixed with Na2B4O7 salt containing 19,9% of 10B isotope. This solutions were used to evaluate thermal and epithermal neutrons and gamma doses at an irradiation cell on BH3 of the IEA-R1 research reactor of IPEN

  11. Neutron Spectra and H*(10) in a 15 MV Linac

    International Nuclear Information System (INIS)

    Neutron spectra and the ambient dose equivalent were calculated inside the bunker of a 15 MV Varian linac model CLINAC iX. Calculations were carried out using Monte Carlo methods. Neutron spectra in the vicinity of isocentre show the presence of evaporation and knock-on neutrons produced by the source term, while epithermal and thermal neutron remain constant regardless the distance respect to isocentre, due to room return. Along the maze neutron spectra becomes softer as the detector moves along the maze. The ambient dose equivalent is decreased but do not follow the 1/r2 rule due to changes in the neutron spectra.

  12. New thermal neutron solid-state electronic detector based on HgI2 crystals

    International Nuclear Information System (INIS)

    We describe the development of a new solid-state electronic neutron detector, based on HgI2 single crystals. Incident neutrons are absorbed in high neutron absorbing foils, such as cadmium or gadolinium, which are placed in front of a HgI2 detector. Gamma rays, emitted as a result of the neutron absorbtion, are then absorbed in the HgI2, generating free charge carriers, which are collected by the electric field. The advantage of this system lies in it's manufacturing simplicity, low weight and small physical dimensions, compared to gas-filled conventional neutron detectors. The disadvantage is that the system does not discriminate between gamma rays and neutrons. A method to minimize this disadvantage is pointed out. It is as well possible to count neutrons by direct exposure of the HgI2 to neutrons. The neutron-to-gamma transformation in that case takes place by the material nuclei themselves. This method, however, is impractical due to the interference of delayed radioactivity whose origin are 129I nuclei. They are generated from 128I by absorbing a neutron, and decay with a 25 min half lifetime involving gamma emissions. (author)

  13. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    Science.gov (United States)

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  14. Fission, spallation or fusion-based neutron sources

    Indian Academy of Sciences (India)

    Kurt N Clausen

    2008-10-01

    In this paper the most promising technology for high power neutron sources is briefly discussed. The conclusion is that the route to high power neutron sources in the foreseeable future is spallation – short or long pulse or even CW – all of these sources will have areas in which they excel.

  15. Properties of Neutron Pixel Detector Based on Medipix-2 Device

    Czech Academy of Sciences Publication Activity Database

    Jakůbek, J.; Holý, T.; Lehmann, E.; Pospíšil, S.; Uher, J.; Vacík, J.; Vavřík, Daniel

    Řím : Nuclear & Plasma Sciences Society, 2004, s. 54. [Nuclear Science Symposium IEEE 2003. Řím (IT), 16.10.2004-22.10.2004] Institutional research plan: CEZ:AV0Z2071913 Keywords : neutron radiography * neutron pixel detector * digital radiography Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  16. Study on palladium determination by neutron activation analysis

    International Nuclear Information System (INIS)

    This study presents results of Pd determinations in neutron activation analysis of spiked biological tissues and CCQM-P63 automotive catalyst. Pd spiked biological tissues of bovine muscle and liver were prepared using a blender with titanium blades and Pd solutions. These materials obtained in a past form were freeze-dried and homogenized before the analysis. Thermal and epithermal neutron activation analyses were applied in these determinations. Separations of Pd from interfering elements were also carried out using solvent extraction and solid-phase extraction techniques, before the irradiations with epithermal neutrons. The irradiations were carried out at the IEA-R1 nuclear research reactor under thermal neutron flux of about 4 x 1012 n cm-2 s-1 during 4 and 16 h for thermal and epithermal irradiations, respectively. The gamma activities of 109Pd of the irradiated samples and Pd standard were measured using an HGe detector coupled to a gamma ray spectrometer. Results obtained in these analyses indicated that the epithermal irradiation presented higher sensitivity, due to the reduction of interferences. The pre-separation procedure of solid-phase extraction applied also yielded low detection limit. Comparisons made between the Pd results obtained using different procedures of neutron activation analysis indicated a good agreement. The analyses carried out in replicates also indicated a good precision with relative standard deviations varying from 1.2 to 14 %. (author)

  17. Boron neutron capture therapy of malignant brain tumors at the Brookhaven Medical Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Joel, D.D.; Coderre, J.A.; Chanana, A.D. [Brookhaven National Lab., Upton, NY (United States). Medical Dept.

    1996-12-31

    Boron neutron capture therapy (BNCT) is a bimodal form of radiation therapy for cancer. The first component of this treatment is the preferential localization of the stable isotope {sup 10}B in tumor cells by targeting with boronated compounds. The tumor and surrounding tissue is then irradiated with a neutron beam resulting in thermal neutron/{sup 10}B reactions ({sup 10}B(n,{alpha}){sup 7}Li) resulting in the production of localized high LET radiation from alpha and {sup 7}Li particles. These products of the neutron capture reaction are very damaging to cells, but of short range so that the majority of the ionizing energy released is microscopically confined to the vicinity of the boron-containing compound. In principal it should be possible with BNCT to selectively destroy small nests or even single cancer cells located within normal tissue. It follows that the major improvements in this form of radiation therapy are going to come largely from the development of boron compounds with greater tumor selectivity, although there will certainly be advances made in neutron beam quality as well as the possible development of alternative sources of neutron beams, particularly accelerator-based epithermal neutron beams.

  18. Gamma-Free Neutron Detector Based upon Lithium Phosphate Nanoparticles

    International Nuclear Information System (INIS)

    A gamma-free neutron-sensitive scintillator is needed to enhance radiation sensing and detection for nonproliferation applications. Such a scintillator would allow very large detectors to be placed at the perimeter of spent-fuel storage facilities at commercial nuclear power plants, so that any movement of spontaneously emitted neutrons from spent nuclear fuel or weapons grade plutonium would be noted in real-time. This task is to demonstrate that the technology for manufacturing large panels of fluor-doped plastic containing lithium-6 phosphate nanoparticles can be achieved. In order to detect neutrons, the nanoparticles must be sufficiently small so that the plastic remains transparent. In this way, the triton and alpha particles generated by the capture of the neutron will result in a photon burst that can be coupled to a wavelength shifting fiber (WLS) producing an optical signal of about ten nanoseconds duration signaling the presence of a neutron emitting source

  19. Gamma-Free Neutron Detector Based upon Lithium Phosphate Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Steven Wallace

    2007-08-28

    A gamma-free neutron-sensitive scintillator is needed to enhance radiaition sensing and detection for nonproliferation applications. Such a scintillator would allow very large detectors to be placed at the perimeter of spent-fuel storage facilities at commercial nuclear power plants, so that any movement of spontaneously emitted neutrons from spent nuclear fuel or weapons grade plutonium would be noted in real-time. This task is to demonstrate that the technology for manufacturing large panels of fluor-doped plastic containing lithium-6 phosphate nanoparticles can be achieved. In order to detect neutrons, the nanoparticles must be sufficiently small so that the plastic remains transparent. In this way, the triton and alpha particles generated by the capture of the neutron will result in a photon burst that can be coupled to a wavelength shifting fiber (WLS) producing an optical signal of about ten nanoseconds duration signaling the presence of a neutron emitting source.

  20. Neutron imaging detector based on the muPIC micro-pixel chamber

    CERN Document Server

    Parker, J D; Fujioka, H; Harada, M; Iwaki, S; Kabuki, S; Kishimoto, Y; Kubo, H; Kurosawa, S; Miuchi, K; Nagae, T; Nishimura, H; Oku, T; Sawano, T; Shinohara, T; Suzuki, J; Takada, A; Tanimori, T; Ueno, K

    2012-01-01

    We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber (muPIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10cm x 10cm and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and 3-dimensional track of each neutron-induced event, allowing the reconstruction of the neutron interaction point with improved accuracy. Using a simple position reconstruction algorithm, a spatial resolution of 349 +/- 36 microns was achieved, with further improvement expected. The detailed tracking allows strong rejection of background gamma-rays, resulting in an effective gamma sensitivity of 10^-12 or less, coupled with stable, robust neutron identification. The detector also features a time resolution of 0.6 microseconds.

  1. The $\\mu$TPC Method: Improving the Position Resolution of Neutron Detectors Based on MPGDs

    CERN Document Server

    Pfeiffer, Dorothea; Birch, Jens; Hall-Wilton, Richard; Höglund, Carina; Hultman, Lars; Iakovidis, George; Oliveri, Eraldo; Oksanen, Esko; Ropelewski, Leszek; Thuiner, Patrik

    2015-01-01

    Due to the Helium-3 crisis, alternatives to the standard neutron detection techniques are becoming urgent. In addition, the instruments of the European Spallation Source (ESS) require advances in the state of the art of neutron detection. The instruments need detectors with excellent neutron detection efficiency, high-rate capabilities and unprecedented spatial resolution. The Macromolecular Crystallography instrument (NMX) requires a position resolution in the order of 200 um over a wide angular range of incoming neutrons. Solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are proposed to meet the new requirements. Charged particles rising from the neutron capture have usually ranges larger than several millimetres in gas. This is apparently in contrast with the requirements for the position resolution. In this paper, we present an analysis technique, new in the field of neutron detection, based on the Time Projection Chamber (TPC) concept. Using a standard Single-GEM with the catho...

  2. An airport cargo inspection system based on X-ray and thermal neutron analysis (TNA)

    International Nuclear Information System (INIS)

    A cargo inspection system incorporating a high-resolution X-ray imaging system with a material-specific detection system based on Ancore Corporation's patented thermal neutron analysis (TNA) technology can detect bulk quantities of explosives and drugs concealed in trucks or cargo containers. The TNA process utilises a 252Cf neutron source surrounded by a moderator. The neutron interactions with the inspected object result in strong and unique gamma-ray signals from nitrogen, which is a key ingredient in modern high explosives, and from chlorinated drugs. The TNA computer analyses the gamma-ray signals and automatically determines the presence of explosives or drugs. The radiation source terms and shielding design of the facility are described. For the X-ray generator, the primary beam, leakage radiation, and scattered primary and leakage radiation were considered. For the TNA, the primary neutrons and tunnel scattered neutrons as well as the neutron-capture gamma rays were considered. (authors)

  3. Neutron imaging detector based on the muPIC micro-pixel chamber

    OpenAIRE

    Parker, J. D.; Hattori, K.; Fujioka, H.; Harada, M; Iwaki, S.; Kabuki, S.; Kishimoto, Y.; Kubo, H.; Kurosawa, S.; Miuchi, K; Nagae, T.; Nishimura, H; Oku, T; SAWANO, T.; Shinohara, T

    2012-01-01

    We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber (muPIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10cm x 10cm and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and 3-dimensional track of each neutron-i...

  4. Materials characterization of radioactive waste forms using a multi-element detection method based on the instrumental neutron activation analysis. MEDINA

    International Nuclear Information System (INIS)

    Radioactive waste has to meet the specifications and acceptance criteria defined by national regulatory and management authorities for its intermediate and final storage. In Germany the Federal Office for Radiation Protection (Bundesamt fuer Strahlenschutz - BfS) has established waste acceptance requirements for the Konrad repository. Konrad is the disposal for radioactive waste with negligible heat generation and is located near the city of Salzgitter and is currently under construction. It will start operation not before the year 2021. The waste-acceptance-requirements are derived from a site-specific safety assessment. They include specific requirements on waste forms, packaging as well as limitations to activities of individual radionuclides and limitations to masses of non-radioactive harmful substances. The amount of chemically toxic elements in the waste is limited in order to avoid pollution of underground water reserves. To comply with these requirements every waste package has to be characterised in its radiological and chemical composition. This characterisation can be performed on the basis of existing documentation or, if the documentation is insufficient, on further analytical analysis. Segmented or integral gamma-scanning as well as active or passive neutron counting are used worldwide as the standard measurement methods for the radiological characterisation and quality checking of radioactive waste. These techniques determine the isotope specific activity of waste packages, but they do not allow the detection of non-radioactive hazardous substances inside the waste packages. Against this background the Institute of Nuclear Engineering and Technology Transfer (NET) at RWTH Aachen University and the Institute of Safety Research and Reactor Technology at Forschungszentrum Juelich jointly develop an innovative non-destructive analytical technique called MEDINA - ''Multi-Element Detection based on Instrumental Neutron Activation'' for

  5. Neutron characterization study for D–T, p-{sup 7}Li neutron sources with new BCA based direct collision coupling method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guan-bo, E-mail: wgb04dep@hotmail.com [Insititute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Yang, Xin [Insititute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Qian, Da-zhi; Li, Run-dong; Tang, Bin [Insititute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900 (China)

    2014-09-01

    The T(D,n){sup 4}He and {sup 7}Li(p,n){sup 7}Be neutron sources have been used for decades in nuclear physics research, stellar nucleosynthesis research and neutron therapy research. In this work, the neutron characterization including neutron yield, spectra, and angular distribution for D–T and p-{sup 7}Li sources have been studied with our new binary collision approximation (BCA) based direct collision coupling method. Distinguished from the traditional path integration method for getting the neutron weight, the new model establishes a relationship between the scattering cross section and the impact parameter, which allows the secondary neutron generation carrying out jointly with ions BCA tracking. The experimental measurements of neutron characterizations have been employed for these two reactions, and the new algorithm is validated.

  6. Time-frequency feature analysis and recognition of fission neutrons signal based on support vector machine

    International Nuclear Information System (INIS)

    Based on the interdependent relationship between fission neutrons (252Cf) and fission chain (235U system), the paper presents the time-frequency feature analysis and recognition in fission neutron signal based on support vector machine (SVM) through the analysis on signal characteristics and the measuring principle of the 252Cf fission neutron signal. The time-frequency characteristics and energy features of the fission neutron signal are extracted by using wavelet decomposition and de-noising wavelet packet decomposition, and then applied to training and classification by means of support vector machine based on statistical learning theory. The results show that, it is effective to obtain features of nuclear signal via wavelet decomposition and de-noising wavelet packet decomposition, and the latter can reflect the internal characteristics of the fission neutron system better. With the training accomplished, the SVM classifier achieves an accuracy rate above 70%, overcoming the lack of training samples, and verifying the effectiveness of the algorithm. (authors)

  7. On-line neutron beam monitoring of the Finnish BNCT facility

    International Nuclear Information System (INIS)

    A Boron Neutron Capture Therapy (BNCT) facility has been built at the FiR 1 research reactor of VTT Chemical Technology in Espoo, Finland. The facility is currently undergoing dosimetry characterisation and neutron beam operation research for clinical trials. The healthy tissue tolerance study, which was carried out in the new facility during spring 1998, demonstrated the reliability and user-friendliness of the new on-line beam monitoring system designed and constructed for BNCT by VTT Chemical Technology. The epithermal neutron beam is monitored at a bismuth gamma shield after an aluminiumfluoride-aluminium moderator. The detectors are three pulse mode U235-fission chambers for epithermal neutron fluence rate and one current mode ionisation chamber for gamma dose rate. By using different detector sensitivities the beam intensity can be measured over a wide range of reactor power levels (0.001-250 kW). The detector signals are monitored on-line with a virtual instrumentation (LabView) based PC-program, which records and displays the actual count rates and total counts of the detectors in the beam. Also reactor in-core power instrumentation and control rod positions can be monitored via another LabView application. The main purpose of the monitoring system is to provide a dosimetric link to the dose in a patient during the treatment, as the fission chamber count rates have been calibrated to the induced thermal neutron fluence rate and to the absorbed dose rate at reference conditions in a tissue substitute phantom

  8. On-line neutron beam monitoring of the Finnish BNCT facility

    Science.gov (United States)

    Tanner, Vesa; Auterinen, Iiro; Helin, Jori; Kosunen, Antti; Savolainen, Sauli

    1999-02-01

    A Boron Neutron Capture Therapy (BNCT) facility has been built at the FiR 1 research reactor of VTT Chemical Technology in Espoo, Finland. The facility is currently undergoing dosimetry characterisation and neutron beam operation research for clinical trials. The healthy tissue tolerance study, which was carried out in the new facility during spring 1998, demonstrated the reliability and user-friendliness of the new on-line beam monitoring system designed and constructed for BNCT by VTT Chemical Technology. The epithermal neutron beam is monitored at a bismuth gamma shield after an aluminiumfluoride-aluminium moderator. The detectors are three pulse mode U 235-fission chambers for epithermal neutron fluence rate and one current mode ionisation chamber for gamma dose rate. By using different detector sensitivities the beam intensity can be measured over a wide range of reactor power levels (0.001-250 kW). The detector signals are monitored on-line with a virtual instrumentation (LabView) based PC-program, which records and displays the actual count rates and total counts of the detectors in the beam. Also reactor in-core power instrumentation and control rod positions can be monitored via another LabView application. The main purpose of the monitoring system is to provide a dosimetric link to the dose in a patient during the treatment, as the fission chamber count rates have been calibrated to the induced thermal neutron fluence rate and to the absorbed dose rate at reference conditions in a tissue substitute phantom.

  9. A source-based fast-neutron facility for precision irradiations

    CERN Document Server

    Scherzinger, J; Davatz, G; Fissum, K G; Gendotti, U; Hall-Wilton, R; Hansson, A; Håkansson, E; Jebali, R; Kanaki, K; Lundin, M; Nilsson, B; Svensson, H

    2014-01-01

    We report on a source-based fast-neutron facility that has been developed for precision irradiations. Well-understood shielding, coincidence, and time-of-flight measurement techniques are employed to produce a polychromatic energy-tagged neutron beam.

  10. Principles and applications of neutron based inspection techniques in counter terrorism

    International Nuclear Information System (INIS)

    Non-intrusive inspection of objects of all sizes, from luggage to shipping containers and from postal parcels to trucks is a vital component of any national security effort from aviation to the control of all land and sea ports of entry.The neutron-based technologies are unique in meeting all key requirements of reliable inspections. They provide accurate, rapid and objective detection of a wide array of threats explosives, chemical agents, nuclear materials and devices, other hazardous materials, drugs, etc. The technologies being currently employed in the field, such as standard x-ray, x-ray based computed tomography, and trace detection (for luggage), and x-ray or γ-ray based radiography (for containers) are inherently deficient for lacking some or all of these key attributes. The neutron-based technologies, on the other hand, possess to various high degrees all the required attributes. They achieve this feat through their penetration and the production and detection of characteristic elemental gamma rays created mainly in two nuclear reactions: (n,γ-) with thermal neutrons and (n,nNγ-) with fast neutrons produced by appropriate accelerators. These nuclear processes are the basis for several inspection technologies such as the TNA (thermal neutron analysis), FNA (fast neutron analysis), PNI (conventional microsecond pulsed neutron inspection combining the previous two), and PFNA (nanosecond pulsed fast neutron analysis). The principles of operation, applications, and advances in inspection systems will be reviewed

  11. Development and calibration of a neutron personal dosemeter using nuclear tracking solid detectors

    International Nuclear Information System (INIS)

    A personal neutron dosimetry, using two fission track solid detectors, with commercial name CR-39 and Makrofol-DE was developed, calibrated and tested. This dosemeter responds to the neutrons in the thermal, epithermal and fast energy intervals. Also, data from the different development phases are presented

  12. Determination of neutronic fluxes in research nuclear reactor of Triga Mark I and WWRS types

    International Nuclear Information System (INIS)

    In this paper is presented the determination of the thermal, epithermal and fast neutron fluxes, using neutron activation analysis technique, for two research nuclear reactors of different design: the Triga Mark I reactor was designed by Gulf General Atomic Co in USA and the WWRS reactor was designed in the URSS, both in the 50's years. (Author)

  13. To gadolinium using for neutron capture therapy researches at WWR-SM reactor

    International Nuclear Information System (INIS)

    The analysis of using gadolinium (isotope and natural) for the medical purposes in neutron-capture therapy of cancer diseases is carried out. Results of definition of the epithermal neutron beam irradiation dose for biological objects with gadolinium-containing preparations are presented by using the WWR-SM reactor. (authors)

  14. Deterioration of performance of neutron moderators under intense irradiation

    International Nuclear Information System (INIS)

    In pulsed neutron sources, fixed moderators such as polyethylene and solid methane slow down fast (MeV) neutrons from the primary source to energies of use for spectroscopy (≤10 eV). Radiation-induced changes in their composition alter their spectral and pulse characteristics. We report the results of fitting time-average spectra from polyethylene and solid methane moderators in Argonne's Intense Pulsed Neutron Source as a function of total fast-neutron radiation dose. The thermal-to-epithermal flux ratio varies most significantly, while the Maxwellian energy and the parameters describing the epithermal component change only slightly. We have used modified forms of Westcott's joining function for this purpose. We provide an integral of the spectrum that is useful for determining the delayed neutron background

  15. Tests of a silicon wafer based neutron collimator

    Energy Technology Data Exchange (ETDEWEB)

    Cussen, L.D. E-mail: leo.cussen@vu.edu.au; Vale, C.J.; Anderson, I.S.; Hoeghoj, P

    2001-10-01

    A Soller slit neutron collimator has been prepared by stacking 160 {mu}m thick single crystal silicon wafers coated on one surface with 4 {mu}m of gadolinium metal. The collimator has an angular width of 20 min full width at half maximum and an effective length of 2.75 cm. The collimator has beam dimensions of 1 cm wide by 5.3 cm high. Tests at neutron wavelengths 7.5A and 1.8A showed a peak transmission of 88% within 2% of the optimum theoretical possibility. The background suppression in the wings is comparable with that of conventional neutron collimators.

  16. Tests of a silicon wafer based neutron collimator

    CERN Document Server

    Cussen, L D; Anderson, I S; Hoeghoj, P

    2001-01-01

    A Soller slit neutron collimator has been prepared by stacking 160 mu m thick single crystal silicon wafers coated on one surface with 4 mu m of gadolinium metal. The collimator has an angular width of 20 min full width at half maximum and an effective length of 2.75 cm. The collimator has beam dimensions of 1 cm wide by 5.3 cm high. Tests at neutron wavelengths 7.5A and 1.8A showed a peak transmission of 88% within 2% of the optimum theoretical possibility. The background suppression in the wings is comparable with that of conventional neutron collimators.

  17. Tests of a silicon wafer based neutron collimator

    International Nuclear Information System (INIS)

    A Soller slit neutron collimator has been prepared by stacking 160 μm thick single crystal silicon wafers coated on one surface with 4 μm of gadolinium metal. The collimator has an angular width of 20 min full width at half maximum and an effective length of 2.75 cm. The collimator has beam dimensions of 1 cm wide by 5.3 cm high. Tests at neutron wavelengths 7.5A and 1.8A showed a peak transmission of 88% within 2% of the optimum theoretical possibility. The background suppression in the wings is comparable with that of conventional neutron collimators

  18. Proposed pulsed neutron source for radiotherapy and radiography

    International Nuclear Information System (INIS)

    Conventional radiation therapy involves low Linear Energy Transfer (LET) radiations like high energy electrons and photons. The basic effects of these ionizing radiations are to destroy the ability of cells to divide, by damaging their DNA strands. For low LET radiations, the damage is induced primarily by activated radicals produced from atomic interactions. Over the energy range of therapeutically used X-rays, typically 100 keV to 25 MeV, approximately the same physical dose needs to be delivered at different energies to reach a given biological endpoint, resulting in similar Relative Biological Effectiveness (RBEs). High LET radiations such as protons, neutrons, however, result in biological damage that is generally larger per unit dose than for X-rays, resulting in an elevated RBE. In case of neutrons, the recoils and nuclear disintegration product contributes to the dose are responsible for a high energy transfer to the biologically active molecules and destroy them in turn. High RBE, LET characteristics and comparatively good Dose Distribution Advantage (DDA), are the main attractive feature of the neutron therapy. As the biological effectiveness of neutrons is high, the required tumor dose is about one third the dose required with photons. Moreover, the tumor cell damaged by low LET radiation has a good chance to repair and continue to grow, while for tumors treated by neutrons the chance for repairing of tumor is very small. Therefore, the neutron therapy is presently realized in two versions: Neutron Capture Therapy (NCT) and the Fast Neutron Therapy (FNT). In NCT, the isotope with large absorption cross-section for thermal/epithermal neutrons is introduced into the body mainly through the blood, while FNT uses fast neutron with high penetrability and treats the malignant tumors of the head, neck, dairy gland, osteogeneous sarcomas, etc. Therefore, in the present paper, considering the importance of the field, the 6 MeV electron accelerator based pulsed

  19. A transportable neutron radiography system based on a SbBe neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Fantidis, J.G. [Laboratory of Nuclear Technology, School of Engineering, ' Democritus' University of Thrace, Xanthi (Greece); Nicolaou, G.E. [Laboratory of Nuclear Technology, School of Engineering, ' Democritus' University of Thrace, Xanthi (Greece)], E-mail: nicolaou@ee.duth.gr; Tsagas, N.F. [Laboratory of Nuclear Technology, School of Engineering, ' Democritus' University of Thrace, Xanthi (Greece)

    2009-07-21

    A transportable neutron radiography system, incorporating a SbBe neutron source, has been simulated using the MCNPX code. Design provisions have allowed two radiography systems to be utilised using the same SbBe neutron source. In this respect, neutron radiographies can be carried out using the photoneutrons produced when the {sup 124}Sb is surrounded by the Be target. Alternatively, {gamma}-radiography can be utilised with the photons from the {sup 124}Sb with the target removed. Appropriate collimators were simulated for each of the radiography modes. Apart from Be, the materials considered were compatible with the European Union Directive on 'Restriction of Hazardous Substances' (RoHS) 2002/95/EC, hence excluding the use of cadmium and lead. Bismuth was chosen as the material for {gamma}-radiation shielding and the proposed system allowed a maximum activity of the {sup 124}Sb up to 1.85x10{sup 13} Bq. The system simulated allows different object sizes to be studied with a wide range of radiography parameters.

  20. A transportable neutron radiography system based on a SbBe neutron source

    International Nuclear Information System (INIS)

    A transportable neutron radiography system, incorporating a SbBe neutron source, has been simulated using the MCNPX code. Design provisions have allowed two radiography systems to be utilised using the same SbBe neutron source. In this respect, neutron radiographies can be carried out using the photoneutrons produced when the 124Sb is surrounded by the Be target. Alternatively, γ-radiography can be utilised with the photons from the 124Sb with the target removed. Appropriate collimators were simulated for each of the radiography modes. Apart from Be, the materials considered were compatible with the European Union Directive on 'Restriction of Hazardous Substances' (RoHS) 2002/95/EC, hence excluding the use of cadmium and lead. Bismuth was chosen as the material for γ-radiation shielding and the proposed system allowed a maximum activity of the 124Sb up to 1.85x1013 Bq. The system simulated allows different object sizes to be studied with a wide range of radiography parameters.

  1. Deep-Subterranean Microbial Habitats in the Hishikari Epithermal Gold Mine: Active Thermophilic Microbial Communities and Endolithic Ancient Microbial Relicts.

    Science.gov (United States)

    Hirayama, H.; Takai, K.; Inagaki, F.; Horikoshi, K.

    2001-12-01

    Deep subterranean microbial community structures in an epithermal gold-silver deposit, Hishikari gold mine, southern part of Kyusyu Japan, were evaluated through the combined use of enrichment culture methods and culture-independent molecular surveys. The geologic setting of the Hishikari deposit is composed of three lithologies; basement oceanic sediments of the Cretaceous Shimanto Supergroup, Quaternary andesites, and auriferous quartz vein. We studied the drilled core rock of these, and the geothermal hot waters from the basement aquifers collected by means of the dewatering system located at the deepest level in the mining sites. Culture-independent molecular phylogenetic analyses of PCR-amplified ribosomal DNA (rDNA) recovered from drilled cores suggested that the deep-sea oceanic microbial communities were present as ancient indigenous relicts confined in the Shimanto basement. On the other hand, genetic signals of active thermophilic microbial communities, mainly consisting of thermophilic hydrogen-oxidizer within Aquificales, thermophilic methanotroph within g-Proteobacteria and yet-uncultivated bacterium OPB37 within b-Proteobacteria, were detected with these of oceanic relicts from the subterranean geothermal hot aquifers (temp. 70-100ºC). Successful cultivation and FISH analyses strongly supported that these thermophilic lithotrophic microorganisms could be exactly active and they grew using geochemically produced hydrogen and methane gasses as nutrients. Based on these results, the deep-subsurface biosphere occurring in the Hishikari epithermal gold mine was delineated as endolithic ancient microbial relicts and modern habitats raising active lithotrophic thermophiles associated with the geological and geochemical features of the epithermal gold deposit.

  2. Accelerator-based neutron tomography cooperating with X-ray radiography

    International Nuclear Information System (INIS)

    Neutron resonance absorption spectroscopy (N-RAS) using a pulsed neutron source can be applied to time-of-flight (TOF) radiography, and the obtained parameters from the peak shape analysis can be reconstructed as the tomograms of nuclide distributions using computed tomography (CT). The problem is that the available spatial resolution is not sufficient for radiography imaging. In this study, we combined neutron and X-ray radiographies to improve the quantitative reconstruction of the neutron tomogram. The accelerator-based neutron source emits X-rays (or gamma-rays) at the same time the neutron pulse is emitted. We utilized the X-ray beam from the neutron source to obtain X-ray radiogram on the same beam line with neutron radiography and then reconstructed the neutron tomogram quantitatively with the help of a detailed sample internal structure obtained from the X-ray radiogram. We calculated the nuclide number density distribution tomogram using a statistical reconstruction procedure, which was easy to include in the structure model during the reconstruction. The obtained result of nuclide number density distribution showed good coincidence with the original object number density.

  3. Detection of residual Al-base core in Ni alloy with Gd-tagging neutron radiography

    International Nuclear Information System (INIS)

    Detection of residual aluminum-base core in nickel alloy is important for manufacturing blades of an aero-engine. Because of the strong penetrability, neutrons are more effective than X-rays to detect residual material in the nickel alloy blade. In this paper, both theoretical calculation and experiments on an accelerator-based neutron source at Peking University are used to verify the feasibility of Gd-tagging neutron radiography in detecting residual aluminum-base core in the nickel alloy. The results show that the technique can achieve a sensitivity of 0.2 mg for the residual core detection. (authors)

  4. Fast-neutron imaging spectrometer based on liquid scintillator loaded capillaries

    Science.gov (United States)

    Mor, I.; Vartsky, D.; Brandis, M.; Goldberg, M. B.; Bar, D.; Mardor, I.; Dangendorf, V.; Bromberger, B.

    2012-04-01

    A fast-neutron imaging detector based on micrometric glass capillaries loaded with high refractive index liquid scintillator has been developed Neutron energy spectrometry is based on event-by-event detection and reconstruction of neutron energy from the measurement of the knock-on proton track length and the amount of light produced in the track. In addition, the detector can provide fast-neutron imaging with position resolution of tens of microns. The detector principle of operation, simulations and experimental results obtained with a small detector prototype are described. We have demonstrated by simulation energy spectrum reconstruction for incident neutrons in the range of 4-20 MeV. The energy resolution in this energy range was 10-15%. Preliminary experimental results of detector spectroscopic capabilities are presented

  5. Determination of the response function for two personal neutron dosemeter designs based on PADC.

    Science.gov (United States)

    Mayer, S; Assenmacher, F; Boschung, M

    2014-10-01

    Since 1998 neutron dosimetry based on PADC (poly allyl diglycol carbonate) is done with a so-called original Paul Scherrer Institute (PSI) design at PSI. The original design (i.e. holder) was later changed. Both designs are optimised for use in workplaces around high-energy accelerators, where the neutron energy spectra are dominated by fast neutrons ranging up to some 100 MeV. In addition to the change of the dosemeter design a new evaluation method based on a microscope scanning technique has been introduced and the etching conditions have been optimised. In the present work, the responses obtained with the original and the new dosemeter designs are compared for fields of radionuclide sources and monoenergetic reference fields using the new evaluation method. The response curves in terms of the personal dose equivalent for normally incident neutrons were built as functions of the incident neutron energy. PMID:24179145

  6. Determination of iodine in foodstuffs consumed in Libya using instrumental and radiochemical neutron activation analysis

    International Nuclear Information System (INIS)

    Iodine was determined in foodstuffs consumed in Libya employing two modes of NAA. The first mode was instrumental using short-time irradiation with epithermal neutrons behind a Cd shield (EINAA). The other mode utilized short-time irradiation with the reactor-pile neutrons followed by radiochemical separation (RNAA). The radiochemical separation procedure was based on the alkaline-oxidative fusion of samples and extraction of elemental iodine into chloroform. Separation yield determined using the radiotracer 131I was within the range of 90 to 95 %. For quality control purposes, standard reference materials were analyzed in both modes employed. Using RNAA, a detection limit of about 1 ng g-1 could be obtained indicating superiority of the method in measuring ultra-trace levels of iodine. On the other hand, more than one order of magnitude higher detection limit did not allow sufficiently accurate determination of iodine in Libyan foodstuffs using EINAA. (author)

  7. Pulsed neutron source based on accelerator-subcritical-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Makoto; Noda, Akira; Iwashita, Yoshihisa; Okamoto, Hiromi; Shirai, Toshiyuki [Kyoto Univ., Uji (Japan). Inst. for Chemical Research

    1997-03-01

    A new pulsed neutron source which consists of a 300MeV proton linac and a nuclear fuel subcritical assembly is proposed. The proton linac produces pulsed spallation neutrons, which are multipied by the subcritical assembly. A prototype proton linac that accelerates protons up to 7MeV has been developed and a high energy section of a DAW structure is studied with a power model. Halo formations in high intensity beam are also being studied. (author)

  8. A variety of neutron sensors based on scintillating glass waveguides

    International Nuclear Information System (INIS)

    Pacific Northwest Laboratory (PNL) has fabricated cerium-activated, lithium-silicate glass scintillating fiber neutron sensors via a hot-downdraw process. These fibers typically have a transmission length (e-1 length) of greater than 2 meters. The underlying physics of, the properties of, and selected devices incorporating these fibers are described. These fibers constitute an enabling technology for a wide variety of neutron sensors

  9. High neutronic efficiency, low current targets for accelerator-based BNCT applications

    International Nuclear Information System (INIS)

    The neutronic efficiency of target/filters for accelerator-based BNCT applications is measured by the proton current required to achieve a desirable neutron current at the treatment port (109 n/cm2/s). In this paper the authors describe two possible targeyt/filter concepts wihch minimize the required current. Both concepts are based on the Li-7 (p,n)Be-7 reaction. Targets that operate near the threshold energy generate neutrons that are close tothe desired energy for BNCT treatment. Thus, the filter can be extremely thin (∼ 5 cm iron). However, this approach has an extremely low neutron yield (n/p ∼ 1.0(-6)), thus requiring a high proton current. The proposed solutino is to design a target consisting of multiple extremely thin targets (proton energy loss per target ∼ 10 keV), and re-accelerate the protons between each target. Targets operating at ihgher proton energies (∼ 2.5 MeV) have a much higher yield (n/p ∼ 1.0(-4)). However, at these energies the maximum neutron energy is approximately 800 keV, and thus a neutron filter is required to degrade the average neutron energy to the range of interest for BNCT (10--20 keV). A neutron filter consisting of fluorine compounds and iron has been investigated for this case. Typically a proton current of approximately 5 mA is required to generate the desired neutron current at the treatment port. The efficiency of these filter designs can be further increased by incorporating neutron reflectors that are co-axial with the neutron source. These reflectors are made of materials which have high scattering cross sections in the range 0.1--1.0 MeV

  10. Study of the RP-10 reactor neutron beam applied to the neutron radiography

    International Nuclear Information System (INIS)

    We have studied the RP-10 reactor radial neutron beam No. 3, which is used for neutron radiographies, by comparing radiograph's with and without the inner duct, and neutron flux determination with in flakes along the external duct, being the presence of photons creating signals at comparable levels of neutron effects, which reduce the quality of the analysis, values around 106 and 104 n/cm2s for thermal and epithermal flux were obtained respectively. It is recommended evaluate the design of the internal duct which presents strong photon emission. (authors).

  11. Development of an accelerator based BNCT facility. Following the Ibaraki BNCT project development process

    International Nuclear Information System (INIS)

    An accelerator-based BNCT (Boron Neutron Capture Therapy) facility is being constructed at the Ibaraki Neutron Medical Research Center. It consists of a proton linac (8 MeV energy and 10 mA average current), a beryllium target, and a moderator system to provide an epi-thermal neutron flux for patient treatment. The technology choices for this present system were driven by the need to site the facility in a hospital and where low residual activity is essential. The maximum neutron energy produced from an 8 MeV-proton is 6 MeV, which is below the threshold energy of the main nuclear reactions which produce radioactive products. The down side of this technology choice is that it produces a high density heat load on the target so that cooling and hydrogen blistering amelioration prevent sever challenges requiring successful R and D progress. The latest design of the target and moderator system shows that a flux of 2.5x109 epi-thermal neutrons/cm2/sec can be obtained. This is two times higher than the flux from the existing nuclear reactor based BNCT facility at JAEA (JRR-4). (author)

  12. [A clinical trial of neutron capture therapy for brain tumors

    International Nuclear Information System (INIS)

    This report describes accomplishments by this laboratory concerning development of high-resolution alpha-autoradiography design of an optimized epithermal neutron beam dosimetry and treatment planning Using Monte Carlo techniques development of a prompt-gamma 10B analysis facility

  13. Correlation of fast neutron, fusion neutron and electron irradiations based on the dislocation loop density

    International Nuclear Information System (INIS)

    The saturated interstitial loop density was examined in Fe-Cr-Ni austenitic ternary alloys irradiated with fast neutrons, fusion neutrons and electrons. Damage rate dependence of the loop density exhibited the effects of difference in nominal (calculated) damage rate (dpa/s) and in the PKA energy spectrum separately. Enhancement of the loop density by cascades was estimated which increased with decreasing temperature and nominal damage rate. Since extensive understanding of the damage rate dependence of loop evolution, which has been obtained by HVEM studies, made the present correlation possible, it is of urgent necessity to acquire reliable models of the damage rate dependence of void evolution for developing a simulation-fusion correlation of void swelling. (orig.)

  14. The IAEA Collaborating Centre for Neutron Activation Based Methodologies of Research Reactors

    International Nuclear Information System (INIS)

    The Reactor Institute Delft was inaugurated in May 2009 as a new IAEA Collaborating Centre for Neutron Activation Based Methodologies of Research Reactors. The collaboration involves education, research and development in (i) Production of reactor-produced, no-carrier added radioisotopes of high specific activity via neutron activation; (ii) Neutron activation analysis with emphasis on automation as well as analysis of large samples, and radiotracer techniques; and, as a cross-cutting activity, (iii) Quality assurance and management in research and application of research reactor based techniques and in research reactor operations. (author)

  15. Interactive data analysis for neutron spectrometers data based on Visual Numerics' PV-WAVE software package

    International Nuclear Information System (INIS)

    The presented work is aimed at the development of tools for data access, visualization, and manipulation of time-of-flight neutron spectrum data acquired from different spectrometers on the IBR-2 fast-pulsed reactor of the Frank Laboratory of Neutron Physics, JINR. Special tools, based on the PV-WAVE software package, for importing neutron data from IBR-2, exporting them in some common format, and data manipulations of such data have been developed by the author. Information about PV-WAVE-based tools for FLNP users is available on the Web. (orig.)

  16. Mechanical strength evaluation of the glass base material in the JRR-3 neutron guide tube

    International Nuclear Information System (INIS)

    The lifetime of the thermal neutron guide tube installed JRR-3 was investigated after 6 years from their first installation. And it was confirmed that a crack had been piercing into the glass base material of the side plate of the neutron guide tube. The cause of the crack was estimated as a static fatigue of the guide tube where an inside of the tube had been evacuated and stressed as well as an embrittlement of the glass base material by gamma ray irradiation. In this report, we evaluate the mechanical strength of the glass base material and estimate the time when the base material gets fatigue fracture. Furthermore, we evaluate a lifetime of the neutron guide tube and confirm the validity of update timing in 2000 and 2001 when the thermal neutron guide tubes T1 and T2 were exchanged into those using the super mirror. (author)

  17. Boron Neutron Capture Therapy for Malignant Brain Tumors

    Science.gov (United States)

    MIYATAKE, Shin-Ichi; KAWABATA, Shinji; HIRAMATSU, Ryo; KUROIWA, Toshihiko; SUZUKI, Minoru; KONDO, Natsuko; ONO, Koji

    2016-01-01

    Boron neutron capture therapy (BNCT) is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of natural elemental boron, is irradiated with low energy thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium-7 nuclei. Therefore, BNCT enables the application of a high dose of particle radiation selectively to tumor cells in which boron-10 compound has been accumulated. We applied BNCT using nuclear reactors for 167 cases of malignant brain tumors, including recurrent malignant gliomas, newly diagnosed malignant gliomas, and recurrent high-grade meningiomas from January 2002 to May 2014. Here, we review the principle and history of BNCT. In addition, we introduce fluoride-18-labeled boronophenylalanine positron emission tomography and the clinical results of BNCT for the above-mentioned malignant brain tumors. Finally, we discuss the recent development of accelerators producing epithermal neutron beams. This development could provide an alternative to the current use of specially modified nuclear reactors as a neutron source, and could allow BNCT to be performed in a hospital setting. PMID:27250576

  18. Compact Intense Neutron Generators Based on Inertial Electrostatic Confinement of D-D Fusion Plasmas

    Science.gov (United States)

    Masuda, K.; Inoue, K.; Kajiwara, T.; Nakamatsu, R.

    2015-10-01

    A neutron generator based on inertial electrostatic confinement (IEC) of fusion plasmas is being developed for a non-destructive inspection system of special nuclear materials hidden in sea containers. The new IEC device is equipped with a multistage feedthrough which was designed aiming at both capability of a high bias voltage and enhancement of ion recirculation by modification of electric fields in the IEC device. Experimental comparison was made with a conventional single-stage IEC device developed in an earlier work. As the results, both the increase in the applied voltage and the modified field symmetry by the new multistage scheme showed significant enhancement in the neutron output. As a consequence, neutron output per input discharge current was enhanced drastically by a factor of ~30 in total. Also, the first pulsing experiments of the newly developed IEC neutron generator showed pulsed neutron output with a rapid pulse fall-off of ~ 1 μsec successfully.

  19. 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.

  20. A cargo inspection system based on pulsed fast neutron analysis (PFNATM)

    International Nuclear Information System (INIS)

    A cargo inspection system based on pulsed fast neutron analysis (PFNATM) is to be used at a border crossing to detect explosives and contraband hidden in trucks and cargo containers. Neutrons are produced by the interaction of deuterons in a deuterium target mounted on a moveable scan arm. The collimated pulsed fast neutron beam is used to determine the location and composition of objects in a cargo container. The neutrons produce secondary gamma rays that are characteristic of the object's elemental composition. The cargo inspection system building consists of an accelerator room and an inspection tunnel. The accelerator room is shielded and houses the injector, accelerator and the neutron production gas target. The inspection tunnel is partially shielded. The truck or container to be inspected will be moved through the inspection tunnel by a conveyor system. The facility and radiation source terms considered in the shielding design are described. (authors)

  1. A research plan based on high intensity proton accelerator Neutron Science Research Center

    Energy Technology Data Exchange (ETDEWEB)

    Mizumoto, Motoharu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    A plan called Neutron Science Research Center (NSRC) has been proposed in JAERI. The center is a complex composed of research facilities based on a proton linac with an energy of 1.5GeV and an average current of 10mA. The research facilities will consist of Thermal/Cold Neutron Facility, Neutron Irradiation Facility, Neutron Physics Facility, OMEGA/Nuclear Energy Facility, Spallation RI Beam Facility, Meson/Muon Facility and Medium Energy Experiment Facility, where high intensity proton beam and secondary particle beams such as neutron, pion, muon and unstable radio isotope (RI) beams generated from the proton beam will be utilized for innovative researches in the fields on nuclear engineering and basic sciences. (author)

  2. Characterisation of an accelerator-based neutron source for BNCT versus beam energy

    CERN Document Server

    Agosteo, S; D'Errico, F; Nath, R; Tinti, R

    2002-01-01

    Neutron capture in sup 1 sup 0 B produces energetic alpha particles that have a high linear energy transfer in tissue. This results in higher cell killing and a higher relative biological effectiveness compared to photons. Using suitably designed boron compounds which preferentially localize in cancerous cells instead of healthy tissues, boron neutron capture therapy (BNCT) has the potential of providing a higher tumor cure rate within minimal toxicity to normal tissues. This clinical approach requires a thermal neutron source, generally a nuclear reactor, with a fluence rate sufficient to deliver tumorcidal doses within a reasonable treatment time (minutes). Thermal neutrons do not penetrate deeply in tissue, therefore BNCT is limited to lesions which are either superficial or otherwise accessible. In this work, we investigate the feasibility of an accelerator-based thermal neutron source for the BNCT of skin melanomas. The source was designed via MCNP Monte Carlo simulations of the thermalization of a fast ...

  3. The three dimensional map of dose components in a head phantom for boron neutron capture therapy

    Directory of Open Access Journals (Sweden)

    Bavarnegin Elham

    2013-01-01

    Full Text Available The in-phantom measurement of physical dose distribution and construction of a convenient phantom is very important for boron neutron capture therapy planning validation. In this study we have simulated a head phantom, suggested for construction in boron neutron capture therapy facilities, and calculated all relevant dose components inside of it using the Monte Carlo code MCNPX. A “generic” epithermal neutron beam with a broad neutron spectrum, similar to beams used for neutron capture therapy clinical trials, was used. The calculated distributions of all relevant dose components in brain tissue equivalent were compared with those in water. The results show that water is a suitable dosimetry material and that the simulated head phantom is a suitable design for producing accurate three-dimensional maps of dose components at enough points inside of the phantom for boron neutron capture therapy dosimetry measurements and the use of these dose maps in beam development and benchmarking of computer-based treatment codes.

  4. An Assessment of Elemental Compositions and Concentrations in a Marble Sample from Hatnub Area using Internal Mono Standard Neutron Activation Analysis

    International Nuclear Information System (INIS)

    A marble sample was taken from Hatnub area near Asyot, where a high pollution is expected. The sample was specially treated and prepared for elemental analysis using the k0-based internal mono standard neutron activation analysis . The irradiation facility of the first Egyptian Training Research Reactor (ETRR-1) was used to irradiate the sample together with gold and zirconium monitor samples. The pneumatic irradiation rabbit system (PIRS) built in the vertical thermal column of the second Egyptian Training Research Reactor (ETRR-2) was used to irradiate another weight of the marble sample and a sample from a certificated reference material JB-1 for short time irradiation. A new method was developed to measure the thermal to epithermal neutron flux ratio and the deviation in the real epithermal neutron spectrum ( 1/E1±alpha ) from the ideal (1/E ). The elemental analysis was carried out by high-resolution gamma-ray spectrometry. The accuracy of the internal mono standard method has been evaluated by analyzing the JB-1 certified reference material

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

    International Nuclear Information System (INIS)

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

  6. ETHERNES: A new design of radionuclide source-based thermal neutron facility with large homogeneity area.

    Science.gov (United States)

    Bedogni, R; Sacco, D; Gómez-Ros, J M; Lorenzoli, M; Gentile, A; Buonomo, B; Pola, A; Introini, M V; Bortot, D; Domingo, C

    2016-01-01

    A new thermal neutron irradiation facility based on an (241)Am-Be source embedded in a polyethylene moderator has been designed, and is called ETHERNES (Extended THERmal NEutron Source). The facility shows a large irradiation cavity (45 cm × 45 cm square section, 63 cm in height), which is separated from the source by means of a polyethylene sphere acting as shadowing object. Taking advantage of multiple scattering of neutrons with the walls of this cavity, the moderation process is especially effective and allows obtaining useful thermal fluence rates from 550 to 800 cm(-2) s(-1) with a source having nominal emission rate 5.7×10(6) s(-1). Irradiation planes parallel to the cavity bottom have been identified. The fluence rate across a given plane is as uniform as 3% (or better) in a disk with 30 cm (or higher) diameter. In practice, the value of thermal fluence rate simply depends on the height from the cavity bottom. The thermal neutron spectral fraction ranges from 77% up to 89%, depending on the irradiation plane. The angular distribution of thermal neutrons is roughly isotropic, with a slight prevalence of directions from bottom to top of the cavity. The mentioned characteristics are expected to be attractive for the scientific community involved in neutron metrology, neutron dosimetry and neutron detector testing. PMID:26516990

  7. Characterization of a thermal neutron beam monitor based on gas electron multiplier technology

    Science.gov (United States)

    Croci, Gabriele; Cazzaniga, Carlo; Claps, Gerardo; Tardocchi, Marco; Rebai, Marica; Murtas, Fabrizio; Vassallo, Espedito; Caniello, Roberto; Cippo, Enrico Perelli; Grosso, Giovanni; Rigato, Valentino; Gorini, Giuseppe

    2014-08-01

    Research into valid alternatives to 3He detectors is fundamental to the affordability of new neutron spallation sources like the European Spallation Source (ESS). In the case of ESS it is also essential to develop high-rate detectors that can fully exploit the increase of neutron flux relative to present neutron sources. One of the technologies fulfilling these requirements is the gas electron multiplier (GEM), since it can combine a high rate capability (MHz/mm2), a coverage area up to 1 m2 and a space resolution better than 0.5 mm. Its use as a neutron detector requires conversion of neutrons into charged particles. This paper describes the realization and characterization of a thermal neutron GEM-based beam monitor equipped with a cathode containing ^{10}B for neutron conversion. This device is constituted by a triple GEM detector whose cathode is made of an aluminum sheet covered by a 1 μ m thick ^{{nat}}B4C layer. The method used to realize a long-lasting ^{{nat}}B4C layer is described and the properties of such a layer have been determined. The detector performances (measured on the ISIS-VESUVIO beam line) in terms of beam profile reconstruction, imaging, and measurement of the thermal neutron beam energy spectrum are compatible with those obtained by standard beam monitors.

  8. Measurement of spatial distribution of neutrons and gamma rays for BNCT using multi-imaging plate system.

    Science.gov (United States)

    Tanaka, Kenichi; Sakurai, Yoshinori; Tanaka, Hiroki; Kajimoto, Tsuyoshi; Takata, Takushi; Takada, Jun; Endo, Satoru

    2015-12-01

    Quality assurance of the spatial distributions of neutrons and gamma rays was tried using imaging plates (IPs) and converters to enhance the beam components in the epithermal neutron mode of the Kyoto University Reactor. The converters used were 4mm thick epoxy resin with B4C at 6.85 weight-percent (wt%) (10)B for epithermal neutrons, and 3mm thick carbon for gamma rays. Results suggested that the IP signal does not need a sensitivity correction regardless of the incident radiation that produces it. PMID:26278346

  9. High yield neutron generator based on a high-current gasdynamic electron cyclotron resonance ion source

    International Nuclear Information System (INIS)

    In present paper, an approach for high yield compact D-D neutron generator based on a high current gasdynamic electron cyclotron resonance ion source is suggested. Results on dense pulsed deuteron beam production with current up to 500 mA and current density up to 750 mA/cm2 are demonstrated. Neutron yield from D2O and TiD2 targets was measured in case of its bombardment by pulsed 300 mA D+ beam with 45 keV energy. Neutron yield density at target surface of 109 s−1 cm−2 was detected with a system of two 3He proportional counters. Estimations based on obtained experimental results show that neutron yield from a high quality TiD2 target bombarded by D+ beam demonstrated in present work accelerated to 100 keV could reach 6 × 1010 s−1 cm−2. It is discussed that compact neutron generator with such characteristics could be perspective for a number of applications like boron neutron capture therapy, security systems based on neutron scanning, and neutronography

  10. Californium-based neutron radiography for corrosion detection in aircraft

    International Nuclear Information System (INIS)

    In support of an overall program aimed at minimizing disassembly and reducing inspection time during aircraft maintenance, a series of projects has been carried out to determine the feasibility of applying neutron radiographic techniques to the nondestructive (NDT) inspection of aircraft and aircraft components. These investigations have clearly demonstrated the superiority of neutron radiography over all other NDT techniques in its ability to detect surface and subsurface corrosion in aircraft structure. This capability is particularly significant where the corrosion is hidden behind thick metallic structural members. The neutron radiographic technique has been applied successfully to detect corrosion in the wing tank of E-2C, C-130, and DC-9 aircraft; rear stabilators of F-4 and F-111 aircraft; aft spar, starboard and port wing, and rudder of the F-8; fuselage skin of the 727; rotary blades of AH-1 and SH-3 helicopters; rotary tail flaps of the UH-2 helicopter; and nose landing gear of A-7 aircraft

  11. Neutron-based techniques for detection of explosives and drugs

    International Nuclear Information System (INIS)

    Neutron reflection, scattering and transmission methods combined with the detection of characteristic gamma rays have an increasing role in the identification of hidden explosives, illicit drugs and other contraband materials. There are about 100 million land mines buried in some 70 countries. Among the abandoned anti-personnel land mines (APL) certain types have low mass (about 100 g) and contain little or no metal. Therefore, these plastic APL cannot be detected by the usual metal detectors. The IAEA Physics Section has organized a CRP in 1999 for the development of novel methods in order to speed up the removing process of APL. The transportation of illicit drugs has shown an increasing trend during the last decade. Developments of fast, non-destructive interrogation methods are required for the inspection of cargo containers, trucks and airline baggage. The major constituents of plastic APL and drugs are H, C, N and O which can be identified by the different neutron interactions. The atom fractions of these elements, in particular the C/O, C/N and C/H ratios, are quite different for drugs and explosives as compared to other materials used to hide them. Recently, we have carried out systematic measurements and calculations on the neutron fields from the 9Be(d,n), 2H(d,n), 252Cf and Pu-Be sources passing through different bulky samples, on the possible use of elastically backscattered Pu-Be neutrons in elemental analysis and on the advantages and limitations of the thermal neutron reflection method in the identification of land mines and illicit drugs. The measured spectral shapes of neutrons were compared with the calculated results using the MCNP-4A and MCNP-4B codes. (author)

  12. Monte Carlo simulation of grating-based neutron phase contrast imaging at CPHS

    International Nuclear Information System (INIS)

    Since the launching of the Compact Pulsed Hadron Source (CPHS) project of Tsinghua University in 2009, works have begun on the design and engineering of an imaging/radiography instrument for the neutron source provided by CPHS. The instrument will perform basic tasks such as transmission imaging and computerized tomography. Additionally, we include in the design the utilization of coded-aperture and grating-based phase contrast methodology, as well as the options of prompt gamma-ray analysis and neutron-energy selective imaging. Previously, we had implemented the hardware and data-analysis software for grating-based X-ray phase contrast imaging. Here, we investigate Geant4-based Monte Carlo simulations of neutron refraction phenomena and then model the grating-based neutron phase contrast imaging system according to the classic-optics-based method. The simulated experimental results of the retrieving phase shift gradient information by five-step phase-stepping approach indicate the feasibility of grating-based neutron phase contrast imaging as an option for the cold neutron imaging instrument at the CPHS.

  13. Logic based feature detection on incore neutron spectra

    International Nuclear Information System (INIS)

    A methodology is proposed to investigate neutron spectra in such a way which is similar to human thinking. The goal was to save experts from tedious, mechanical tasks of browsing a large amount of signals in order to recognize changes in the underlying mechanisms. The general framework for detecting features of incore neutron spectra with a rulebased methodology is presented. As an example, the meaningful peaks in the APSDs are determined. This method is a part of a wider project to develop a noise diagnostic expert system. (R.P.) 6 refs.; 6 figs.; 1 tab

  14. Elemental analysis of brazing alloy samples by neutron activation technique

    International Nuclear Information System (INIS)

    Two brazing alloy samples (C P2 and C P3) have been investigated by Neutron activation analysis (NAA) technique in order to identify and estimate their constituent elements. The pneumatic irradiation rabbit system (PIRS), installed at the first egyptian research reactor (ETRR-1) was used for short-time irradiation (30 s) with a thermal neutron flux of 1.6 x 1011 n/cm2/s in the reactor reflector, where the thermal to epithermal neutron flux ratio is 106. Long-time irradiation (48 hours) was performed at reactor core periphery with thermal neutron flux of 3.34 x 1012 n/cm2/s, and thermal to epithermal neutron flux ratio of 79. Activation by epithermal neutrons was taken into account for the (1/v) and resonance neutron absorption in both methods. A hyper pure germanium detection system was used for gamma-ray acquisitions. The concentration values of Al, Cr, Fe, Co, Cu, Zn, Se, Ag and Sb were estimated as percentages of the sample weight and compared with reported values. 1 tab

  15. Monte-Carlo simulation of cement neutron field distribution characteristics in PGNAA

    International Nuclear Information System (INIS)

    The distribution characteristics of the neutron field in cement was simulated using the MCNP code to comply with the requirements of an online Prompt Gamma Neutron Activation Analysis system. Simulation results showed that the neutron relative flux proportion reduced with increasing cement thickness. When the cement thickness remains unchanged, the reduced proportion of thermal neutrons increases to a small extent, but the epithermal, intermediate, and fast neutrons will decrease according to the geometric progression. H element in the cement mainly affects the reduction of fast neutrons and other single-substance elements, e.g., O, Ca, 56Fe, Si, and Al. It also slows down the reduction of the fast neutrons via inelastic scattering. O contributes more than other elements in the reduction of fast neutrons. Changing the H content affects the thermal, epithermal, intermediate, and fast neutrons, while changing the Ca, Fe, and Si contents only influences the thermal, epithermal, and intermediate neutrons; hence, there is little effect on the reduction of fast neutrons. (authors)

  16. Neutron flux profile determination for an in-pool animal irradiation facility

    Energy Technology Data Exchange (ETDEWEB)

    Bose, S.R.; Mulder, R.U.; Rydin, R.A. [Univ. of Virginia, Charlottesville, VA (United States)] [and others

    1997-12-01

    The University of Virginia 2-MW pool-type nuclear research reactor (UVAR) is used actively for neutron activation analysis, neutron radiography, gemstone coloration, radioisotope production, neutron transmutation doping, and, more recently, medical research. Neutron beams for neutron radiography are extracted from the southeast and southwest edges of the core. While excellent for radiography, the flux intensity of these beams is much too low to permit their use in medical research. Therefore, planning has begun for the installation of a filtered epithermal neutron beamport with flux suitable for boron neutron capture therapy (BNCT) of human cancers. The design of this beamport has been reported previously.

  17. Neutron flux profile determination for an in-pool animal irradiation facility

    International Nuclear Information System (INIS)

    The University of Virginia 2-MW pool-type nuclear research reactor (UVAR) is used actively for neutron activation analysis, neutron radiography, gemstone coloration, radioisotope production, neutron transmutation doping, and, more recently, medical research. Neutron beams for neutron radiography are extracted from the southeast and southwest edges of the core. While excellent for radiography, the flux intensity of these beams is much too low to permit their use in medical research. Therefore, planning has begun for the installation of a filtered epithermal neutron beamport with flux suitable for boron neutron capture therapy (BNCT) of human cancers. The design of this beamport has been reported previously

  18. Neutron dosimetry and microdosimetry with track etch based LET spectrometer

    Czech Academy of Sciences Publication Activity Database

    Jadrníčková, Iva; Spurný, František; Brabcová, Kateřina

    Buenos Aires : SAR, 2008. s. 13-13. [International Congress of the International Radiation Protection Association /12./. 19.10.2008-24.10.2008, Buenos Aires] Institutional research plan: CEZ:AV0Z10480505 Keywords : neutron dosimetry * LET spectrometry * detectors Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders

  19. Novel Boron-10-based detectors for Neutron Scattering Science

    CERN Document Server

    Piscitelli, Francesco

    2015-01-01

    Nowadays neutron scattering science is increasing its instrumental power. Most of the neutron sources in the world are pushing the development of their technologies to be more performing. The neutron scattering development is also pushed by the European Spallation Source (ESS) in Sweden, a neutron facility which has just started construction. Concerning small area detectors (1m^2), the 3He technology, which is today cutting edge, is reaching fundamental limits in its development. Counting rate capability, spatial resolution and cost-e?ectiveness, are only a few examples of the features that must be improved to ful?fill the new requirements. On the other hand, 3He technology could still satisfy the detector requirements for large area applications (50m^2), however, because of the present 3He shortage that the world is experiencing, this is not practical anymore. The recent detector advances (the Multi-Grid and the Multi-Blade prototypes) developed in the framework of the collaboration between the Institut Laue...

  20. Neutron-based land mine detection system development

    Energy Technology Data Exchange (ETDEWEB)

    Davis, H.A.; McDonald, T.E. Jr.; Nebel, R.A.; Pickrell, M.M.

    1997-10-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project was to examine the feasibility of developing a land mine detection system that can detect nonmetallic (plastic) mines using the detection and analysis of prompt gamma neutron activation analysis (PGNAA). The authors approached this study by first carrying out a review of other nonmetallic land mine detection methods for comparison with the PGNAA concept. They reviewed issues associated with detecting and recording the return gamma signal resulting from neutrons interacting with high explosive in mines and they examined two neutron source technologies that have been under development at Los Alamos for the past several years for possible application to a PGNAA system. A major advantage of the PGNAA approach is it`s ability to discriminate detection speed and need for close proximity. The authors identified approaches to solving these problems through development of improved neutron sources and detection sensors.