WorldWideScience

Sample records for accelerator-based neutron source

  1. Accelerator based steady state neutron source

    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

  2. An accelerator based steady state neutron source

    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.)

  3. Use of accelerator based neutron sources

    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

  4. Accelerator based neutron source for neutron capture therapy

    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

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

    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.

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

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

    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)

  8. Characterisation of an accelerator-based neutron source for BNCT versus beam energy

    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 ...

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

    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.

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

    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

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

    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.

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

    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

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

    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)

  14. Study of medical RI production with accelerator-based neutron sources

    The single-photon emission computed tomography (SPECT) and positron emission tomography (PET) have been widely adopted for nuclear medicine imaging to make diagnoses of body functions, identification of site of cancers, and so on. Now, almost all of medical radio isotopes are produced by nuclear reactors or charged particle accelerators. We propose a new route to produce the medical radio isotopes with accelerator-based neutron sources. In this paper, as an example, we introduce the proposed production method of 99Mo, which is the mother nuclide of 99mTc for SPECT. We determined the 100Mo(n,2n)99Mo reaction cross section to 1,415±82mb and it was consistent with the value (1,398mb) obtained from JENDL-4.0. Therefore, it indicates yields of produced RIs can be predicted with nuclear data based simulations. The simulation also can be used to design irradiation condition. In this paper some results of the simulations are also shown. (author)

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

    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.

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

    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

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

    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.)

  18. Accelerator-based neutron source using a cold deuterium target with degenerate electrons

    R. E. Phillips

    2013-07-01

    Full Text Available A neutron generator is considered in which a beam of tritons is incident on a hypothetical cold deuterium target with degenerate electrons. The energy efficiency of neutron generation is found to increase substantially with electron density. Recent reports of potential targets are discussed.

  19. Imaging of Texture, Crystallite Size and Strain in Materials Using Accelerator Based Pulsed Neutron Sources

    The pulsed neutron transmission method can give position dependent information on crystallographic microstructure, such as preferred orientation, crystallite size and strain for thick materials, for which the X ray cannot be applied, since the pulsed neutron measurements enable researchers to obtain neutron transmission spectrums depending on position by using a position sensitive detector. Furthermore, the transmission spectrums reflect the total neutron cross-section containing information of the crystallographic structure. By analysing the transmission spectrums, spatially dependent information can be obtained. An in situ transmission measurement was performed during a tensile test of an iron sample with notches. The results clearly showed changes of anisotropy, crystallite size and strain dependent on the load. (author)

  20. An accelerator-based epithermal photoneutron source for BNCT

    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.

  1. Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy

    Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes.

  2. Accelerator-based neutron radioscopic systems

    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

  3. Design study of Be-target for proton accelerator based neutron source with 13MeV cyclotron

    There is a cyclotron named KIRAMS-13 in Pusan National University, Busan, Korea, which has the proton energy of 13MeV and the beam current of 0.05mA. Originally, it was developed for producing medical radioisotopes and nuclear physics research. To improve the utilization of the facility, we are considering the possibilities of installing a neutron generation target in it. The Beryllium target has been considered and neutrons can be generated by 9Be(p,n)9B reaction above the threshold proton energy of 2.057MeV. In this presentation, we suggest candidate materials and structures, thicknesses, metal layers and cooling systems of target, which is optimal for the KIRAMS-13. We chose the Beryllium material of 1.14mm thick, which is calculated by stopping power of Beryllium, based on PSTAR, NIST. As for the cooling system, we chose to use water as a coolant, which will also act as a moderator. As protons pass through the target, hydrogen ions continue to pile up in the material and this makes the material brittle. To solve this problem, we chose Vanadium material because it has high hydrogen diffusion coefficient and short half-life isotope after being activated by neutrons. We simulated the neutron characteristics by the Monte Carlo simulation code, Geant4, CERN and performed thermal analysis on the target. The design of target system is very important to produce neutrons for the desired purposes. There are several other existing facilities in Korea, in addition to the cyclotron facility considered in this study, where new neutron target system can be installed and neutrons can be generated. Two prominent facilities are KOMAC, Gyeongju and RFT-30, Jeongeup and we are planning to do study on the possibilities of utilizing the accelerators for neutron generation.

  4. Accelerator Based Neutron Beams for Neutron Capture Therapy

    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

  5. Accelerator Based Neutron Beams for Neutron Capture Therapy

    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

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

    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)

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

    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. Beryllium Target for Accelerator - Based Boron Neutron Capture Therapy

    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

  9. Accelerator-based neutron tomography cooperating with X-ray radiography

    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.

  10. High neutronic efficiency, low current targets for accelerator-based BNCT applications

    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

  11. Neutron sources

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

  12. Optimisation of resolution in accelerator-based fast neutron radiography

    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...

  13. Pulsed neutron sources for epithermal neutrons

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

  14. Neutron scattering and spallation neutron sources

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

  15. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    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

  16. A National Spallation Neutron Source for neutron scattering

    The National Spallation Neutron Source is a collaborative project or perform the conceptual design for a next generation neutron source for the Department of Energy. This paper reviews the need and justification for a new neutron source, the origins and structure of the collaboration formed to address this need, and the community input leading up to the current design approach. A reference design is presented for an accelerator based spallation neutron source that would begin operation at about 1 megawatt of power but designed so that it could be upgraded to significantly higher powers in the future. The technology approach, status, and progress on the conceptual design to date are presented

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

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

    2016-07-01

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

  18. Development of a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy

    We describe the present status of an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based (AB)-BNCT. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the 7Li(p,n)7Be reaction. The machine currently being constructed is a folded TESQ with a high-voltage terminal at 0.6 MV. We report here on the progress achieved in a number of different areas.

  19. Laser wakefield accelerator based light sources: potential applications and requirements

    Albert, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). NIF and Photon Sciences; Thomas, A. G. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences; Mangles, S. P.D. [Imperial College, London (United Kingdom). Blackett Lab.; Banerjee, S. [Univ. of Nebraska, Lincoln, NE (United States); Corde, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Flacco, A. [ENSTA, CNRS, Ecole Polytechnique, Palaiseau (France); Litos, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Neely, D. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Viera, J. [Univ. of Lisbon (Portugal). GoLP-Inst. de Plasmas e Fusao Nuclear-Lab. Associado; Najmudin, Z. [Imperial College, London (United Kingdom). Blackett Lab.; Bingham, R. [Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL). Central Laser Facility; Joshi, C. [Univ. of California, Los Angeles, CA (United States). Dept. of Electrical Engineering; Katsouleas, T. [Duke Univ., Durham, NC (United States). Platt School of Engineering

    2015-01-15

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  20. Laser wakefield accelerator based light sources: potential applications and requirements

    In this article we review the prospects of laser wakefield accelerators as next generation light sources for applications. This work arose as a result of discussions held at the 2013 Laser Plasma Accelerators Workshop. X-ray phase contrast imaging, X-ray absorption spectroscopy, and nuclear resonance fluorescence are highlighted as potential applications for laser-plasma based light sources. We discuss ongoing and future efforts to improve the properties of radiation from plasma betatron emission and Compton scattering using laser wakefield accelerators for these specific applications.

  1. An optimized neutron-beam shaping assembly for accelerator-based BNCT

    Different materials and proton beam energies have been studied in order to search for an optimized neutron production target and beam shaping assembly for accelerator-based BNCT. The solution proposed in this work consists of successive stacks of Al, polytetrafluoroethylene, commercially known as Teflon[reg ], and LiF as moderator and neutron absorber, and Pb as reflector. This assembly is easy to build and its cost is relatively low. An exhaustive Monte Carlo simulation study has been performed evaluating the doses delivered to a Snyder model head phantom by a neutron production Li-metal target based on the 7Li(p,n)7Be reaction for proton bombarding energies of 1.92, 2.0, 2.3 and 2.5 MeV. Three moderator thicknesses have been studied and the figures of merit show the advantage of irradiating with near-resonance-energy protons (2.3 MeV) because of the relatively high neutron yield at this energy, which at the same time keeps the fast neutron healthy tissue dose limited and leads to the lowest treatment times. A moderator of 34 cm length has shown the best performance among the studied cases

  2. Strengthening the inherent safety and security of radioactive sources: Accelerator based options

    First and foremost, radioactive sources are both useful and cost effective. If a technology can't be utilized in an effective manner, it won't be useful, no matter how clever and elegant it is. Secondly, there are safety and proliferation concerns that must be addressed. Accidents, contamination, dirty bombs, etc., all represent real concerns. A single incident can impact the cost of all uses. These issues and regulations devised to reduce these risks are driving up the costs and lowering efficiency. An alternative would be the accelerator based option, which is nothing new, it has been around for decades. Using accelerator technologies to produce radiation will address the issues I raise by limiting the production of radiation to only those times when a switch has been flipped. Producing radiation that way has one main advantage over the use of radioactive sources. When the switch is off, there is no radiation. Making instruments that are doubly fail-safe is straightforward. Issues associated with radiation safety during transport and storage disappear. There are also minimal issues of disposal and tracking of materials. There is very little potential for diverting a transportable radiography machine or portable neutron generator for nefarious uses. There is a need to carefully monitor the balance between the increasing number of radioactive sources in use, increasing concern for their location and condition, and the cost of employing radiation generators. In many cases there will be a natural progression away from using sources towards the use of radiation generators. Another key factor that would influence this balance is if an accident and or misuse of radioactive sources were to occur. The costs of dealing with sources would rapidly escalate, and would likely tip the balance sooner

  3. Spallation Neutron Source (SNS)

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

  4. Neutron sources: Present practice and future potential

    The present capability and future potential of accelerator-based monoenergetic and white neutron sources are outlined in the context of fundamental and applied neutron-nuclear research. The neutron energy range extends from thermal to 500 MeV, and the time domain from steady-state to pico-second pulsed sources. Accelerator technology is summarized, including the production of intense light-ion, heavy-ion and electron beams. Target capabilities are discussed with attention to neutron-producing efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: fundamental neutron-nuclear research, nuclear data acquisition, materials damage studies, engineering tests, and biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections. 90 refs., 4 figs

  5. Properties of neutron sources

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

  6. Novel design concepts for generating intense accelerator based beams of mono-energetic fast neutrons

    Full text: Successful application of neutron techniques in research, medicine and industry depends on the availability of suitable neutron sources. This is particularly important for techniques that require mono-energetic fast neutrons with well defined energy spread. There are a limited number of nuclear reactions available for neutron production and often the reaction yield is low, particularly for thin targets required for the production of mono-energetic neutron beams. Moreover, desired target materials are often in a gaseous form, such as the reactions D(d,n)3He and T(d,n)3He, requiring innovative design of targets, with sufficient target pressure and particle beam handling capability. Additional requirements, particularly important in industrial applications, and for research institutions with limited funds, are the cost effectiveness as well as small size, coupled with reliable and continuous operation of the system. Neutron sources based on high-power, compact radio-frequency quadrupole (RFQ) linacs can satisfy these criteria, if used with a suitable target system. This paper discusses the characteristics of a deuteron RFQ linear accelerator system coupled to a high pressure differentially pumped deuterium target. Such a source, provides in excess of 1010 mono- energetic neutrons per second with minimal slow neutron and gamma-ray contamination, and is utilised for a variety of applications in the field of mineral identification and materials diagnostics. There is also the possibility of utilising a proposed enhanced system for isotope production. The RFQ linear accelerator consists of: 1) Deuterium 25 keV ion source injector; 2) Two close-coupled RFQ resonators, each powered by an rf amplifier supplying up to 300 kW of peak power at 425 MHz; 3) High energy beam transport system consisting of a beam line, a toroid for beam current monitoring, two steering magnets and a quadrupole triplet for beam focusing. Basic technical specifications of the RFQ linac are

  7. Neutron sources and applications

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

    1994-01-01

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

  8. Neutron sources and applications

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

  9. Measurement and analysis of the radio frequency radiation (non-ionizing) in DC accelerator based 14 MeV neutron generator facility

    Radio frequency (RF) driven ion sources are used in various scientific applications like neutral beam injection systems for fusion reactors, particle accelerators, proton therapy machines, ion implantation systems, neutron generator and neutron spallation source. In BARC, a DC accelerator based 14 MeV neutron generator uses RF type ion source for generation of deuterium ion beam current that is used in DT reaction for neutron generation. An indigenously developed RF amplifier system, capacitively couples (via two electrode rings) the RF power at 100 MHz to deuterium gas filled RF ion source assembly. The RF radiation (non ionizing radiation) emanates from the capacitively coupling that is in the form of circular electrode (metal) rings across deuterium plasma column. A very minor RF leakage may arise from the amplifier assembly itself. This total radiation was measured at various locations within the neutron generator facility and also in two set ups. It was then quantified, analyzed and qualified from the allowed RF emissions standards. This would and have ensured equipment and personnel safety in addition to avoiding of the radio frequency interference (RFI) towards other instrumentation. This paper describes in detail all these measurements and their analysis done. (author)

  10. An Accelerator Neutron Source for BNCT

    The overall goal of this project was to develop an accelerator-based neutron source (ABNS) for Boron Neutron Capture Therapy (BNCT). Specifically, our goals were to design, and confirm by measurement, a target assembly and a moderator assembly that would fulfill the design requirements of the ABNS. These design requirements were (1) that the neutron field quality be as good as the neutron field quality for the reactor-based neutron sources for BNCT, (2) that the patient treatment time be reasonable, (3) that the proton current required to treat patients in reasonable times be technologically achievable at reasonable cost with good reliability, and accelerator space requirements which can be met in a hospital, and finally (4) that the treatment be safe for the patients

  11. An Accelerator Neutron Source for BNCT

    Blue, Thomas, E

    2006-03-14

    The overall goal of this project was to develop an accelerator-based neutron source (ABNS) for Boron Neutron Capture Therapy (BNCT). Specifically, our goals were to design, and confirm by measurement, a target assembly and a moderator assembly that would fulfill the design requirements of the ABNS. These design requirements were 1) that the neutron field quality be as good as the neutron field quality for the reactor-based neutron sources for BNCT, 2) that the patient treatment time be reasonable, 3) that the proton current required to treat patients in reasonable times be technologially achievable at reasonable cost with good reliability, and accelerator space requirements which can be met in a hospital, and finally 4) that the treatment be safe for the patients.

  12. Condensed matter and materials research using neutron diffraction and spectroscopy: reactor and pulsed neutron sources

    The paper provides a short, and partial view of the neutron scattering technique applied to condensed matter and materials research. Reactor and accelerator-based neutron spectrometers are discussed, together with examples of research projects that illustrate the puissance and modern applications of neutron scattering. Some examples are chosen to show the range of facilities available at the medium flux reactor operated by Casaccia ENEA, Roma and the advanced, pulsed spallation neutron source at the Rutherford Appleton Laboratory, Oxfordshire. (author)

  13. Advances in boron neutron capture therapy (BNCT) at kyoto university - From reactor-based BNCT to accelerator-based BNCT

    Sakurai, Yoshinori; Tanaka, Hiroki; Takata, Takushi; Fujimoto, Nozomi; Suzuki, Minoru; Masunaga, Shinichiro; Kinashi, Yuko; Kondo, Natsuko; Narabayashi, Masaru; Nakagawa, Yosuke; Watanabe, Tsubasa; Ono, Koji; Maruhashi, Akira

    2015-07-01

    At the Kyoto University Research Reactor Institute (KURRI), a clinical study of boron neutron capture therapy (BNCT) using a neutron irradiation facility installed at the research nuclear reactor has been regularly performed since February 1990. As of November 2014, 510 clinical irradiations were carried out using the reactor-based system. The world's first accelerator-based neutron irradiation system for BNCT clinical irradiation was completed at this institute in early 2009, and the clinical trial using this system was started in 2012. A shift of BCNT from special particle therapy to a general one is now in progress. To promote and support this shift, improvements to the irradiation system, as well as its preparation, and improvements in the physical engineering and the medical physics processes, such as dosimetry systems and quality assurance programs, must be considered. The recent advances in BNCT at KURRI are reported here with a focus on physical engineering and medical physics topics.

  14. Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

    In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the 7Li(p, n)7Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

  15. Pulsed spallation Neutron Sources

    Carpenter, J.M. [Argonne National Lab., IL (United States)

    1994-12-31

    This paper reviews the early history of pulsed spallation neutron source development at Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provides a few examples of applications in fundamental condensed matter physics, materials science and technology.

  16. Pulsed spallation Neutron Sources

    This paper reviews the early history of pulsed spallation neutron source development at Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provides a few examples of applications in fundamental condensed matter physics, materials science and technology

  17. Pulsed spallation neutron sources

    This paper reviews the early history of pulsed spallation neutron source development ar Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provide a few examples of applications in fundamental condensed matter physics, materials science and technology

  18. Novel design concepts for creating and utilizing intense accelerator based beams of mono-energetic fast neutrons

    The delivered intensity from neutron sources plays a major role in the applicability of neutron techniques. This is particularly true when the application requires mono-energetic neutron beams. Development of such neutron sources depends on two main factors; i) the output ion beam current from the accelerator and, ii) the design of the target system for generating neutrons. The design of an intense monoenergetic neutron source reported in this paper is based on a radio-frequency quadrupole deuteron linac system, coupled to a novel high pressure differentially pumped deuterium gas target. The operation of a working system, capable of generating in excess of 1010 neutrons per second is reported, along with examples of diverse applications. Also discussed are proposed improvements to the design, such that in excess of 1012 neutron per second will be generated. (author)

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

    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...

  20. Intense pulsed neutron sources

    Kustom, R.L.

    1981-01-01

    Accelerator requirements for pulsed spallation neutron sources are stated. Brief descriptions of the Argonne IPNS-I, the Japanese KENS, Los Alamos Scientific Laboratory WNR/PSR, the Rutherford Laboratory SNS, and the West German SNQ facilities are presented.

  1. Accelerators for Driving Intense spallation Neutron Sources

    A worldwide trend to replace aging research reactors with accelerator driven neutron sources is currently underway. The ''SARAF'' program at Soreq NRC is a notable example. Setting the background to this trend, a review of the history of accelerator based spallation neutron sources is presented. We follow the evolution of ideas and projects for intense spallation neutron sources. The survey is mainly focused on the properties of the accelerators chosen as drivers throughout the evolution of spallation neutron sources. Since the late 1940s, high-energy proton and deuteron accelerators were developed in view of producing intense neutron sources for various applications related to the nuclear industry, i.e. breeding fissile isotopes, driving nuclear reactors using alternative fuels (like the 'Energy Amplifier') and nuclear waste incineration. However, these projects never progressed beyond the R and D stage. In recent years there is a trend to replace aging reactor-based strong cw neutron sources by pulsed intense spallation sources. Their main applications are in the fields of physics research, material sciences, biology and medicine. Prominent examples of successful projects are ISIS at RAL in Great Britain and SINQ at PSI in Switzerland. Other successful projects are noted in Japan and the US. The clear success of these spallation sources prompted the development of a new generation of more intense spallation neutron sources, notably in Europe (ESS), US (SNS) and Japan (JAERI). Generally, the pulsed spallation neutron sources are based on high-energy proton accelerators. Initially, the proton accelerators were room temperature linacs. In view of the progress relating to properties of RF superconducting resonators and the excellent accumulated experience with cryogenic accelerators, future accelerators for spallation sources will be mostly cryogenic linacs

  2. The relationship between contrast, resolution and detectability in accelerator-based fast neutron radiography

    Fast neutron radiography as a method for non destructive testing is a fast growing field of research. At the Schonland Research Center for Nuclear Sciences we have been engaged in the formulation of a model for the physics of image formation in fast neutron radiography (FNR). This involves examining all the various factors that affect image formation in FNR by experimental and Monte Carlo methods. One of the major problems in the development of a model for fast neutron radiography is the determination of the factors that affect image contrast and resolution. Monte Carlo methods offer an ideal tool for the determination of the origin of many of these factors. In previous work the focus of these methods has been the determination of the scattered neutron field in both a scintillator and a fast neutron radiography facility. As an extension of this work MCNP has been used to evaluate the role neutron scattering in a specimen plays in image detectability. Image processing of fast neutron radiographs is a necessary method of enhancing the detectability of features in an image. MCNP has been used to determine the part it can play in indirectly improving image resolution and aiding in image processing. The role noise plays in fast neutron radiography and its impact on image reconstruction has been evaluated. All these factors aid in the development of a model describing the relationship between contrast, resolution and detectability

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

    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

  4. Report of the advisory group meeting on optimal use of accelerator-based neutron generators

    During the past 20 to 25 years, the IAEA has provided a number of laboratories in the developing member states with neutron generators. These neutron generators were originally supplied for the primary purpose of neutron activation analysis. In order to promote the optimal use of these machines, a meeting was held in 1996, resulting in a technical document manual for the upgrading and troubleshooting of neutron generators. The present meeting is a follow-up to that earlier meeting. There are several reasons why some neutron generators are not fully utilized. These include lack of infrastructure, such as an appropriate shielded building and loss of adequately trained technical and academic personnel. Much of the equipment is old and lacking spare parts, and in a few cases there is a critical lack of locally available knowledge and experience in accelerator technology. The report contains recommendations for dealing with these obstacles

  5. Accelerator-based BNCT

    The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. In particular, the present status and recent progress of the Argentine project will be reviewed. The topics will cover: intense ion sources, accelerator tubes, transport of intense beams, beam diagnostics, the 9Be(d,n) reaction as a possible neutron source, Beam Shaping Assemblies (BSA), a treatment room, and treatment planning in realistic cases. - Highlights: • The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. • Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. • The present status and recent progress of the Argentine project will be reviewed. • Topics cover intense ion sources, accelerator tubes, transport of intense beams and beam diagnostics, among others

  6. Status of spallation neutron source

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

    1997-03-01

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

  7. 350 keV accelerator-based neutron transmission setup at KFUPM for hydrogen detection

    Naqvi, A; Maslehuddin, M; Kidwai, S; Nassar, R

    2002-01-01

    An experimental setup has been developed to determine hydrogen contents of bulk samples using fast neutron transmission technique. Neutrons with 3 MeV energy were produced via D(d, n) reaction. The neutrons transmitted through the sample were detected by a NE213 scintillation detector. Preliminary tests of the setup were carried out using soil samples with different moisture contents. In addition to experimental study, Monte Carlo simulations were carried out to generate calibration curve of the experimental setup. Finally, experimental tests results were compared with the results of Monte Carlo simulations. A good agreement has been obtained between the simulation results and experimental results.

  8. Coded source neutron imaging

    Bingham, Philip R [ORNL; Santos-Villalobos, Hector J [ORNL

    2011-01-01

    Coded aperture techniques have been applied to neutron radiography to address limitations in neutron flux and resolution of neutron detectors in a system labeled coded source imaging (CSI). By coding the neutron source, a magnified imaging system is designed with small spot size aperture holes (10 and 100 m) for improved resolution beyond the detector limits and with many holes in the aperture (50% open) to account for flux losses due to the small pinhole size. An introduction to neutron radiography and coded aperture imaging is presented. A system design is developed for a CSI system with a development of equations for limitations on the system based on the coded image requirements and the neutron source characteristics of size and divergence. Simulation has been applied to the design using McStas to provide qualitative measures of performance with simulations of pinhole array objects followed by a quantitative measure through simulation of a tilted edge and calculation of the modulation transfer function (MTF) from the line spread function. MTF results for both 100um and 10um aperture hole diameters show resolutions matching the hole diameters.

  9. Californium-252 neutron sources

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

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

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    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 u...

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

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    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 ...

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

    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)

  13. Plasma focus neutron source

    A neutron source not permanently active is obtained from an electric discharge plasma focus (PF) device. A small PF device, a Mather model device, works in the limit of low energy, 100 to 200 J at charging voltage of 20 to 30 kV with a capacitor bank of 160 nF, and a characteristic inductance of 25 to 50 nH. A theoretical model leads us to estimate the optimum values of capacitance, inductance, initial charging voltage and electrode geometry. In this work is presented the design evolution and construction of a first PF neutron source prototype, preliminary measures of current, voltage and temporal evolution of the current with the end of have an electric characterization. This parameters must be optimized with the objective of geeting an emission of 104 to 105 neutrons per pulse when Deuterium is used like filled gas (C.W)

  14. Neutron source multiplication method

    Extensive use has been made of neutron source multiplication in thousands of measurements of critical masses and configurations and in subcritical neutron-multiplication measurements in situ that provide data for criticality prevention and control in nuclear materials operations. There is continuing interest in developing reliable methods for monitoring the reactivity, or k/sub eff/, of plant operations, but the required measurements are difficult to carry out and interpret on the far subcritical configurations usually encountered. The relationship between neutron multiplication and reactivity is briefly discussed and data presented to illustrate problems associated with the absolute measurement of neutron multiplication and reactivity in subcritical systems. A number of curves of inverse multiplication have been selected from a variety of experiments showing variations observed in multiplication during the course of critical and subcritical experiments where different methods of reactivity addition were used, with different neutron source detector position locations. Concern is raised regarding the meaning and interpretation of k/sub eff/ as might be measured in a far subcritical system because of the modal effects and spectrum differences that exist between the subcritical and critical systems. Because of this, the calculation of k/sub eff/ identical with unity for the critical assembly, although necessary, may not be sufficient to assure safety margins in calculations pertaining to far subcritical systems. Further study is needed on the interpretation and meaning of k/sub eff/ in the far subcritical system

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

    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...

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

    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

  17. High-efficiency neutron generator system as a neutron source for NCT

    The new target system as an accelerator-based neutron source was investigated for NCT. This system is composed of multilayer of thin films of several kinds of materials (ex, Ta, Be) to improve the efficiency of neutron production. The LA150 cross-section library for Tantalum and an extrapolation value of experimental data for Beryllium was used to optimize the energy and current of the incident proton beam. The optimized system is a good prospect for cyclotron-based NCT. (author)

  18. Neutron source for Neutron Capture Synovectomy

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

  19. Electrostatic design and beam transport for a folded tandem electrostatic quadrupole accelerator facility for accelerator-based boron neutron capture therapy

    Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT), we discuss here the electrostatic design of the machine, including the accelerator tubes with electrostatic quadrupoles and the simulations for the transport and acceleration of a high intensity beam.

  20. Accelerator based-boron neutron capture therapy (BNCT)-clinical QA and QC

    Alpha-particle and recoil Li atom yielded by the reaction (10B, n), due to their high LET properties, efficiently and specifically kill the cancer cell that has incorporated the boron. Efficacy of this boron neutron capture therapy (BNCT) has been demonstrated mainly in the treatment of recurrent head/neck and malignant brain cancers in Kyoto University Research Reactor Institute (KUR). As the clinical trial of BNCT is to start from 2009 based on an accelerator (not on the Reactor), this paper describes the tentative outline of the standard operation procedure of BNCT for its quality assurance (QA) and quality control (QC) along the flow of its clinical practice. Personnel concerned in the practice involve the attending physician, multiple physicians in charge of BNCT, medical physicists, nurses and reactor stuff. The flow order of the actual BNCT is as follows: Pre-therapeutic evaluation mainly including informed consent and confirmation of the prescription; Therapeutic planning including setting of therapy volume, and of irradiation axes followed by meeting for stuffs' agreement, decision of irradiating field in the irradiation room leading to final decision of the axis, CT for the planning, decision of the final therapeutic plan according to Japan Atomic Energy Agency-Computational Dosimetry System (JCDS) and meeting of all related personnel for the final confirmation of therapeutic plan; and BNCT including the transport of patient to KUR, dripping of boronophenylalanine, setting up of the patient on the machine, blood sampling for pharmacokinetics, boron level measurement for decision of irradiating time, switch on/off of the accelerator, confirmation of patient's movement in the irradiated field after the neutron irradiation, blood sampling for confirmation of the boron level, and patient's leave from the room. The QA/QC check is principally to be conducted with the two-person rule. The purpose of the clinical trial is to establish the usefulness of BNCT, and

  1. PREFACE: 6th Workshop on Infrared Spectroscopy and Microscopy with Accelerator-Based Sources (WIRMS11)

    Lupi, Stefano; Perucchi, Andrea

    2012-05-01

    This volume of Journal of Physics: Conference Series is dedicated to a subset of papers related to the work presented at the 6th edition of the international Workshop on Infrared Spectroscopy and Microscopy with Accelerator-Based Sources (WIRMS), held in Trieste, Italy, September 4-8 2011. Previous editions of the conference were held in Porquerolles (France), Lake Tahoe (USA), Rathen (Germany), Awaji (Japan), and Banff (Canada). This edition was organized and chaired by Stefano Lupi (Roma La Sapienza) and co-chaired by Andrea Perucchi (Elettra), with the support of the Italian Synchrotron Light Laboratory ELETTRA, which was honored to host the WIRMS workshop in its tenth anniversary. The 6th WIRMS edition addressed several different topics, ranging from biochemistry to strongly correlated materials, from geology to conservation science, and from forensics to the study of cometary dusts. Representatives from the infrared scientific programs at synchrotron light sources and free-electron-laser facilities. This edition was attended by 88 participants, including representatives from the infrared scientific programs at synchrotron light sources and free-electron-laser facilities, who enjoyed the stimulating scientific presentations, several detailed discussions, and the beautiful weather and scenery of the Trieste gulf. Participants came from 16 different nations and four continents, including many young scientists, six of which were supported by the organizers. There were 45 scientific talks divided in 11 sessions: Facilities, Microspectroscopy (I, II, III), Time-Resolved Spectroscopies, Extreme Conditions, Condensed Matter, Near-Field, Imaging, THz Techniques and High-Resolution Spectroscopy. 37 posters were also presented at two very lively evening poster sessions. We would like to use the opportunity of writing this preface to thank all the participants of the workshop for the very high level of their scientific contribution and for the very friendly atmosphere

  2. Activity report of the fusion neutronics source from April 1, 2001 to March 31, 2004

    The Fusion Neutronics Source (FNS) is an accelerator based 14 MeV neutron generator established in 1981. FNS is a powerful tool for neutronics research aiming the fusion reactor development such as neutron cross section measurements, integral experiments and blanket neutronics experiments. This report reviews the FNS activities in the period from April 1, 2001 to March 31, 2004, including collaboration with universities and other research institutes. The 35 papers are indexed individually. (J.P.N.)

  3. Absolute determination of the neutron source yield using melamine as a neutron detector

    Ciechanowski, M.; Bolewski, A., Jr.; Kreft, A.

    2015-01-01

    A new approach to absolute determination of the neutron source yield is presented. It bases on the application of melamine (C3H6N6) to neutron detection combined with Monte Carlo simulations of neutron transport. Melamine has the ability to detect neutrons via 14N(n, p)14C reaction and subsequent determination of 14C content. A cross section for this reaction is relatively high for thermal neutrons (1.827 b) and much lower for fast neutrons. A concentration of 14C nuclei created in the irradiated sample of melamine can be reliably measured with the aid of the accelerator mass spectrometry (AMS). The mass of melamine sufficient for this analysis is only 10 mg. Neutron detection is supported by Monte Carlo simulations of neutron transport carried out with the use of MCNP-4C code. These simulations are aimed at computing the probability of 14C creation in the melamine sample per the source neutron. The result of AMS measurements together with results of MCNP calculations enable us to determine the number of neutrons emitted from the source during the irradiation of melamine. The proposed method was applied for determining the neutron emission from a commercial 252Cf neutron source which was independently calibrated. The measured neutron emission agreed with the certified one within uncertainty limits. The relative expanded uncertainty (k=2) of the absolute neutron source yield determination was estimated at 2.6%. Apart from calibration of radionuclide neutron sources the proposed procedure could facilitate absolute yield measurements for more complex sources. Potential applications of this methodology as it is further developed include diagnostics of inertial confinement fusion and plasma-focus experiments, calibration of neutron measurement systems at tokamaks and accelerator-based neutron sources as well as characterization of neutron fields generated in large particle detectors during collisions of hadron beams.

  4. Isotopic neutron sources for neutron activation analysis

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

  5. Accelerator tube construction and characterization for a tandem-electrostatic-quadrupole for accelerator-based boron neutron capture therapy

    The accelerator tubes are essential components of the accelerator. Their function is to transport and accelerate a very intense proton or deuteron beam through the machine, from the ion source to the neutron production target, without significant losses. In this contribution, we discuss materials selected for the tube construction, the procedures used for their assembly and the testing performed to meet the stringent requirements to which it is subjected.

  6. Sources of ultracold neutrons

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

  7. High-power electron beam tests of a liquid-lithium target and characterization study of (7)Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy.

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Cohen, D; Eliyahu, I; Kijel, D; Mardor, I; Silverman, I

    2014-06-01

    A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (σ=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors. PMID:24387907

  8. Optimal Neutron Source and Beam Shaping Assembly for Boron Neutron Capture Therapy

    There were three objectives to this project: (1) The development of the 2-D Swan code for the optimization of the nuclear design of facilities for medical applications of radiation, radiation shields, blankets of accelerator-driven systems, fusion facilities, etc. (2) Identification of the maximum beam quality that can be obtained for Boron Neutron Capture Therapy (BNCT) from different reactor-, and accelerator-based neutron sources. The optimal beam-shaping assembly (BSA) design for each neutron source was also to e obtained. (3) Feasibility assessment of a new neutron source for NCT and other medical and industrial applications. This source consists of a state-of-the-art proton or deuteron accelerator driving and inherently safe, proliferation resistant, small subcritical fission assembly

  9. Optimal Neutron Source and Beam Shaping Assembly for Boron Neutron Capture Therapy

    Vujic, J L; Greenspan, E; Guess, S; Karni, Y; Kastenber, W E; Kim, L; Leung, K N; Regev, D; Verbeke, J M; Waldron, W L; Zhu, Y

    2003-01-01

    There were three objectives to this project: (1) The development of the 2-D Swan code for the optimization of the nuclear design of facilities for medical applications of radiation, radiation shields, blankets of accelerator-driven systems, fusion facilities, etc. (2) Identification of the maximum beam quality that can be obtained for Boron Neutron Capture Therapy (BNCT) from different reactor-, and accelerator-based neutron sources. The optimal beam-shaping assembly (BSA) design for each neutron source was also to e obtained. (3) Feasibility assessment of a new neutron source for NCT and other medical and industrial applications. This source consists of a state-of-the-art proton or deuteron accelerator driving and inherently safe, proliferation resistant, small subcritical fission assembly.

  10. Optimal Neutron Source & Beam Shaping Assembly for Boron Neutron Capture Therapy

    J. Vujic; E. Greenspan; W.E. Kastenber; Y. Karni; D. Regev; J.M. Verbeke, K.N. Leung; D. Chivers; S. Guess; L. Kim; W. Waldron; Y. Zhu

    2003-04-30

    There were three objectives to this project: (1) The development of the 2-D Swan code for the optimization of the nuclear design of facilities for medical applications of radiation, radiation shields, blankets of accelerator-driven systems, fusion facilities, etc. (2) Identification of the maximum beam quality that can be obtained for Boron Neutron Capture Therapy (BNCT) from different reactor-, and accelerator-based neutron sources. The optimal beam-shaping assembly (BSA) design for each neutron source was also to e obtained. (3) Feasibility assessment of a new neutron source for NCT and other medical and industrial applications. This source consists of a state-of-the-art proton or deuteron accelerator driving and inherently safe, proliferation resistant, small subcritical fission assembly.

  11. Neutron scattering instruments for the Spallation Neutron Source

    The Spallation Neutron Source (SNS) is an accelerator-based short-pulse neutron scattering facility designed to meet the needs of the neutron scattering community in the US well into the next century. SNS is a US Department of Energy (DOE) construction project that is planned to be completed at Oak Ridge National Laboratory late in 2005. SNS is being designed and will be constructed by a 5-laboratory collaboration including Argonne National Laboratory, Brookhaven National Laboratory, Lawrence Berkeley National Laboratory, Los Alamos National Laboratory and Oak Ridge National Laboratory. The functional requirements for the SNS have been set by the scientific community and DOE. SNS will initially operate at 1 MW with one target station operating at 60 Hz and having 18 beam ports for neutron scattering experiments. The first 10 neutron scattering instruments are provided as part of the SNS construction project, and will be selected to span the types of science anticipated to be most important for this facility on the basis of input from the user community. This paper describes the process of selection and design of these first 10 instruments. The extensive R and D program to support the design and construction of these instruments and to help pave the way for future instruments will also be discussed. A set of 10 reference instruments has been developed to help establish the layout of the experiment hall and the interface between the instruments and the target station. This layout and some of the associated interface issues will be described. Examples of the design and performance of some of these reference instruments will also be discussed as an indication of the types of instrumentation involved and the new scientific capabilities that should be available when the SNS becomes operational

  12. Pulsed neutron sources at Dubna

    In 1960 the first world repetitively pulsed reactor IBR was put into operation. It was the beginning of the story how fission based pulsed neutron sources at Dubna have survived. The engineers involved have experienced many successes and failures in the course of new sources upgrading to finally come to possess the world's brightest neutron source - IBR-2. The details are being reviewed through the paper. The fission based pulsed neutron sources did not reach their final state as yet- the conceptual views of IBR prospects are being discussed with the goal to double the thermal neutron peak flux (up to 2x1016) and to enhance the cold neutron flux by 10 times (with the present one being as high that of the ISIS cold moderator). (author)

  13. A bright neutron source driven by relativistic transparency of solids

    Roth, M.; Jung, D.; Falk, K.; Guler, N.; Deppert, O.; Devlin, M.; Favalli, A.; Fernandez, J.; Gautier, D. C.; Geissel, M.; Haight, R.; Hamilton, C. E.; Hegelich, B. M.; Johnson, R. P.; Kleinschmidt, A.; Merrill, F.; Schaumann, G.; Schoenberg, K.; Schollmeier, M.; Shimada, T.; Taddeucci, T.; Tybo, J. L.; Wagner, F.; Wender, S. A.; Wilde, C. H.; Wurden, G. A.

    2016-03-01

    Neutrons are a unique tool to alter and diagnose material properties and excite nuclear reactions with a large field of applications. It has been stated over the last years, that there is a growing need for intense, pulsed neutron sources, either fast or moderated neutrons for the scientific community. Accelerator based spallation sources provide unprecedented neutron fluxes, but could be complemented by novel sources with higher peak brightness that are more compact. Lasers offer the prospect of generating a very compact neutron source of high peak brightness that could be linked to other facilities more easily. We present experimental results on the first short pulse laser driven neutron source powerful enough for applications in radiography. For the first time an acceleration mechanism (BOA) based on the concept of relativistic transparency has been used to generate neutrons. This mechanism not only provides much higher particle energies, but also accelerated the entire target volume, thereby circumventing the need for complicated target treatment and no longer limited to protons as an intense ion source. As a consequence we have demonstrated a new record in laser-neutron production, not only in numbers, but also in energy and directionality based on an intense deuteron beam. The beam contained, for the first time, neutrons with energies in excess of 100 MeV and showed pronounced directionality, which makes then extremely useful for a variety of applications. The results also address a larger community as it paves the way to use short pulse lasers as a neutron source. They can open up neutron research to a broad academic community including material science, biology, medicine and high energy density physics as laser systems become more easily available to universities and therefore can complement large scale facilities like reactors or particle accelerators. We believe that this has the potential to increase the user community for neutron research largely.

  14. Industrial applications of accelerator-based infrared sources: Analysis using infrared microspectroscopy

    Bantignies, J.L.; Fuchs, G.; Wilhelm, C. [Elf Atochem, Pierre-Benite (France); Carr, G.L. [Brookhaven National Lab., Upton, NY (United States). National Synchrotron Light Source; Dumas, P. [Centre Univ. Paris-Sud, Orsay (France)

    1997-09-01

    Infrared Microspectroscopy, using a globar source, is now widely employed in the industrial environment, for the analysis of various materials. Since synchrotron radiation is a much brighter source, an enhancement of an order of magnitude in lateral resolution can be achieved. Thus, the combination of IR microspectroscopy and synchrotron radiation provides a powerful tool enabling sample regions only few microns size to be studied. This opens up the potential for analyzing small particles. Some examples for hair, bitumen and polymer are presented.

  15. Design of long neutron counter for intensified D-T neutron source

    A low sensitivity long neutron counter was designed as a standard directional flow detector to monitor neutron fluence reference values of an accelerator-based 14 MeV D-T neutron source with yield about 1013 n/s. The energy response over 6 MeV was improved using a tungsten radiator, which acts as an energy converter via the (n, xn) reaction. Different parameters were optimized to flatten the neutron energy response over a wide energy range. A simulation of the designed long neutron counter using the Monte Carlo codes MCNP was undergone. The response function is relatively flat in the energy range of 1 keV-20 MeV. The results show the maximal relative variation is about 7.8%. (author)

  16. Characteristics of fast neutron sources

    The contributions of a poster session from a clinical radiotherapy conference are reviewed and discussed with respect to economic aspects. The contributions were concerned with the optimum neutron treatment source for neutron therapy. The neutron sources considered were D-T generators with either metal hydride or gaseous targets, cyclotrons, nuclear reactors, proton linear accelerators and a pion facility. All facilities would appear to cost more than cobalt units or 4-6 MeV electron accelerators. From the radiobiological studies to date, there is little data to support the selection of one energy cyclotron over another. It is concluded that no neutron source will achieve the desirable physics characteristics of 4-6 MeV electrons and only the more expensive sources will achieve a depth dose similar to a cobalt unit. (UK)

  17. Compact, energy EFFICIENT neutron source: enabling technology for various applications

    Hershcovitch, A.; Roser, T.

    2009-12-01

    A novel neutron source comprising of a deuterium beam (energy of about 100 KeV) injected into a tube filled with tritium gas and/or tritium plasma that generates D-T fusion reactions, whose products are 14.06 MeV neutrons and 3.52 MeV alpha particles, is described. At the opposite end of the tube, the energy of deuterium ions that did not interact is recovered. Beryllium walls of proper thickness can be utilized to absorb 14 MeV neutrons and release 2-3 low energy neutrons. Each ion source and tube forms a module. Larger systems can be formed from multiple units. Unlike currently proposed methods, where accelerator-based neutron sources are very expensive, large, and require large amounts of power for operation, this neutron source is compact, inexpensive, easy to test and to scale up. Among possible applications for this neutron source concept are sub-critical nuclear breeder reactors and transmutation of radioactive waste.

  18. Fission-Fusion Neutron Source

    Full text of publication follows: In order to meet the requirement of fusion reactor developing and nuclear waste treatment, a concept of fission-fusion neutron source has been proposed with LiD cylinder in heavy water region of China Advanced Research Reactor (CARR) by slow neutrons to transfer to fusion neutron. The principal is the reaction of 6Li(n,α) to produce energetic tritium ion with 2.739 MeV in LiD by slow neutron, which will be bombarding the deuteron of LiD to induce fusion reaction to produce 14 MeV neutron. The fusion reaction rate will increase with the accumulation of tritium in LiD by the reaction between tritium and deuteron recoils produced by 14 MeV neutrons. When the concentration of tritium in LiD reaches O.5 x 1022 T/cm3 and the fraction of fusion reaction induced by deuteron recoils with tritium approaches to 1, the 14 MeV neutron flux will be doubled and redoubled increasing to approach saturation in which the produced tritium at time t is exhausted by fusion reaction to keep the constant of tritium concentration in LiD. At this case the 14 MeV neutron production rate is too high, it has to decrease the slow neutron flux with decreasing CARR reactor power progressively when the fusion neutron flux approaches to presetting value, for example 3.5 x 1014 n/cm2 sec and will approach to saturation at the low level of neutron flux. This paper describes the principle of fission-fusion neutron source, including the production rate of fusion neutron, the accumulation rate and concentration of tritium, the fusion reaction rate induced by deuteron recoils with tritium, the 14 MeV neutron flux of inner surface of LiD cylinder in the heavy water region of CARR reactor without neutron depression and the influence factors. To consider the neutron depression an assembly of LiD rods in 20 x 20 cm with a centre hole in CARR reactor must be designed to optimize the fusion neutron flux in centre hole. (author)

  19. The tokamak as a neutron source

    This paper describes the tokamak in its role as a neutron source, with emphasis on experimental results for D-D neutron production. The sections summarize tokamak operation, sources of fusion and non-fusion neutrons, principal neutron detection methods and their calibration, neutron energy spectra and fluxes outside the tokamak plasma chamber, history of neutron production in tokamaks, neutron emission and fusion power gain from JET and TFTR (the largest present-day tokamaks), and D-T neutron production from burnup of D-D tritons. This paper also discusses the prospects for future tokamak neutron production and potential applications of tokamak neutron sources. 100 refs., 16 figs., 4 tabs

  20. Materials for spallation neutron sources

    The Workshop on Materials for Spallation Neutron Sources at the Los Alamos Neutron Science Center, February 6 to 10, 1995, gathered scientists from Department of Energy national laboratories, other federal institutions, universities, and industry to discuss areas in which work is needed, successful designs and use of materials, and opportunities for further studies. During the first day of the workshop, speakers presented overviews of current spallation neutron sources. During the next 3 days, seven panels allowed speakers to present information on a variety of topics ranging from experimental and theoretical considerations on radiation damage to materials safety issues. An attempt was made to identify specific problems that require attention within the context of spallation neutron sources. This proceedings is a collection of summaries from the overview sessions and the panel presentations

  1. Materials for spallation neutron sources

    Sommer, W.F.; Daemen, L.L. [comps.

    1996-03-01

    The Workshop on Materials for Spallation Neutron Sources at the Los Alamos Neutron Science Center, February 6 to 10, 1995, gathered scientists from Department of Energy national laboratories, other federal institutions, universities, and industry to discuss areas in which work is needed, successful designs and use of materials, and opportunities for further studies. During the first day of the workshop, speakers presented overviews of current spallation neutron sources. During the next 3 days, seven panels allowed speakers to present information on a variety of topics ranging from experimental and theoretical considerations on radiation damage to materials safety issues. An attempt was made to identify specific problems that require attention within the context of spallation neutron sources. This proceedings is a collection of summaries from the overview sessions and the panel presentations.

  2. Source characterization of Purnima Neutron Generator (PNG)

    The use of 14.1 MeV neutron generators for the applications such as elemental analysis, Accelerated Driven System (ADS) study, fast neutron radiography requires the characterization of neutron source i.e neutron yield (emission rate in n/sec), neutron dose, beam spot size and energy spectrum. In this paper, a series of experiments carried out to characterize this neutron source. The neutron source has been quantified with neutron emission rate, neutron dose at various source strength and beam spot size at target position

  3. The Elettra and FERMI: Two accelerator-based radiation sources in Trieste

    Elettra is the Italian third generation synchrotron radiation laboratory located on the Triestinian Carso plateau. It is built around a medium energy electron storage ring operated between 2 and 2.4 GeV. The Elettra beamlines cover a wide energy range, from the far infrared to the hard x-rays, as the photon energy ranges between 2 meV and 40 keV, i.e. wavelengths between 0.6 mm and 0.3 A. Moreover, an existing LINAC, previously used as injector for the storage ring is being upgraded and converted into a Free Electron Laser (FEL), FERMI at ELETTRA (Free Electron laser Radiation for Multidisciplinary Investigations at Elettra) FEL. Both sources are built and operated by the Sincrotrone Trieste public no profit company. Beamlines are often built in collaboration with external partners from different scientific institutions, both Italian and from other countries. Together with the synchrotron radiation activity, Elettra hosts several support and complementary laboratories, which makes it a multidisciplinary Research and Service center, competitive at the international level by employing advanced micro/nano analytical, photolithographic and radiographic techniques. Researchers at Elettra are active in fields as diverse as genomics, pharmacology, biomedicine, catalysis and chemical processes, microelectronics and micromechanics. This wide range of applications makes the site an international crossroad where researchers, coming from different countries and disciplines and from academic and applied research, interact and exchange in a competitive, yet friendly, atmosphere, producing new knowledge and training junior researchers. Training of younger generations of scientists and engineers for research and industry is indeed one of the missions of the Sincrotrone Trieste public company. (author)

  4. Application of a Bonner sphere spectrometer for the determination of the angular neutron energy spectrum of an accelerator-based BNCT facility

    Experimental activities are underway at INFN Legnaro National Laboratories (LNL) (Padua, Italy) and Pisa University aimed at angular-dependent neutron energy spectra measurements produced by the 9Be(p,xn) reaction, under a 5 MeV proton beam. This work has been performed in the framework of INFN TRASCO-BNCT project. Bonner Sphere Spectrometer (BSS), based on 6LiI (Eu) scintillator, was used with the shadow-cone technique. Proper unfolding codes, coupled to BSS response function calculated by Monte Carlo code, were finally used. The main results are reported here. - Highlights: • Bonner sphere spectrometer is used to determine the angular neutron energy spectrum of an accelerator-based BNCT facility. • The shadow-cone technique is a method used with Bonner sphere spectrometer to remove the neutron scattered contribution. • The response function matrix for the set of Bonner sphere spectrometer is calculated by Monte Carlo code. • Unfolding codes are used to obtain neutron spectra at different neutron emission angles (0°, 40°, 80° and 120°)

  5. Simplified neutron detector for angular distribution measurement of p-Li neutron source

    Boron Neutron Capture Therapy (BNCT) is one of the most promising cancer therapies using 10B(n, α)7Li nuclear reaction. Because nuclear reactor is currently used for BNCT, the therapy is much restricted. Many kinds of accelerator based neutron sources for BNCT are being investigated worldwide and p-Li reaction is one of the most promising candidates because the emitted neutron energy is comparatively low and no gamma-ray is produced. To use p-Li neutron source for BNCT, measurement of the angular distribution is important. However, the energy of neutrons changes depending on the angle with respect to the proton beam, e.g., the energy of forward emitted neutrons are about 700 keV and it is 100 keV for backward direction. So a neutron detector, the efficiency of which is not dependent on energy, is needed. Though so-called “Long Counter” is known to be available, its structure is complicated and moreover it is expensive. Thus we have designed and developed a simplified neutron detector using Monte Carlo simulation. We verified the developed detector experimentally and measured the angular distribution in detail for p-Li reaction by using it. The obtained results were compared with analytical calculations. (author)

  6. New neutron physics using spallation sources

    The extraordinary neutron intensities available from the new spallation pulsed neutron sources open up exciting opportunities for basic and applied research in neutron nuclear physics. The energy range of neutron research which is being explored with these sources extends from thermal energies to almost 800 MeV. The emphasis here is on prospective experiments below 100 keV neutron energy using the intense neutron bursts produced by the Proton Storage Ring (PSR) at Los Alamos. 30 refs., 10 figs

  7. Design of a neutron source for calibration

    The neutron spectra produced by an isotopic neutron source located at the center of moderating media were calculated using Monte Carlo method in the aim to design a neutron source for calibration purposes. To improve the evaluation of the dosimetric quantities, is recommended to calibrate the radiation protection devices with calibrated neutron sources whose neutron spectra being similar to those met in practice. Here, a 239Pu-Be neutron source was inserted in H2O, D2O and polyethylene cylindrical moderators in order to produce neutron spectra that resembles spectra found in workplaces

  8. HANARO Cold Neutron Source Design

    The cold neutron source (CNS) design has been completed and confirmed by the full scale mock-up test. When its licensing is expected to be issued within 2007, the CNS will be installed in HANARO in 2009 and be operated from 2010 after the commissioning. The production of cold neutrons from 2009 will enable the neutron guides and the scattering instruments to be commissioned in parallel. From 2010, a new era of neutron science will be open in the area of biotechnology, nano-technology, and material science through the probing capability of cold neutrons with nano-wavelength. The prominent research output that will be created from this cold neutron research facility will ensure the basic science and technology, which will provide the strong foundation for the advanced engineering and technology. This paper presents the design of in-pool assembly including the nuclear design of moderator cell, the manufacturing test of in-pool assembly, the full scale mock-up test, and the safety analysis

  9. Optical polarizing neutron devices designed for pulsed neutron sources

    Takeda, M.; Kurahashi, K.; Endoh, Y. [Tohoku Univ, Sendai (Japan); Itoh, S. [National Lab. for High Energy Physics, Tsukuba (Japan)

    1997-09-01

    We have designed two polarizing neutron devices for pulsed cold neutrons. The devices have been tested at the pulsed neutron source at the Booster Synchrotron Utilization Facility of the National Laboratory for High Energy Physics. These two devices proved to have a practical use for experiments to investigate condensed matter physics using pulsed cold polarized neutrons.

  10. Neutron-emission measurements at a white neutron source

    Haight, Robert C [Los Alamos National Laboratory

    2010-01-01

    Data on the spectrum of neutrons emittcd from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A ''white'' neutron source (continuous in energy) allows measurements over a wide range of neutron energies all in one experiment. We use the tast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron-gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of the fission neutron spectra from {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.

  11. Neutron spectra produced by moderating an isotopic neutron source

    A Monte Carlo study has been carried out to determine the neutron spectra produced by an isotopic neutron source inserted in moderating media. Most devices used for radiation protection have a response strongly dependent on neutron energy. ISO recommends several neutron sources and monoenergetic neutron radiations, but actual working situations have broad spectral neutron distributions extending from thermal to MeV energies, for instance, near nuclear power plants, medical applications accelerators and cosmic neutrons. To improve the evaluation of the dosimetric quantities, is recommended to calibrate the radiation protection devices in neutron spectra which are nearly like those met in practice. In order to complete the range of neutron calibrating sources, it seems useful to develop several wide spectral distributions representative of typical spectra down to thermal energies. The aim of this investigation was to use an isotopic neutron source in different moderating media to reproduce some of the neutron fields found in practice. MCNP code has been used during calculations, in these a 239PuBe neutron source was inserted in H2O, D2O and polyethylene moderators. Moderators were modeled as spheres and cylinders of different sizes. In the case of cylindrical geometry the anisotropy of resulting neutron spectra was calculated from 0 to 2. From neutron spectra dosimetric features were calculated. MCNP calculations were validated by measuring the neutron spectra of a 239PuBe neutron source inserted in a H2O cylindrical moderator. The measurements were carried out with a multisphere neutron spectrometer with a 6LiI(Eu) scintillator. From the measurements the neutron spectrum was unfolded using the BUNKIUT code and the UTA4 response matrix. Some of the moderators with the source produce a neutron spectrum close to spectra found in actual applications, then can be used during the calibration of radiation protection devices

  12. Neutron sources for the medical use

    Recently encouraging results of the neutron radiation therapy have been obtained in clinical trials. In addition to the therapy, the neutrons are applied to the diagnosis besides the production of radioisotopes, that is, in-vivo activation analysis and neutron radiograph. In the medicine, high energy neutrons are effectively used. The necessary conditions, especially neutron source reactions, angular distributions, etc., and the neutron dosimetry including neutron kerma factors are discussed. Finally the requirements for neutron sources, their related problems and nuclear data are enumerated. (author)

  13. High power accelerator-based boron neutron capture with a liquid lithium target and new applications to treatment of infectious diseases

    A new conceptual design for an accelerator-based boron neutron capture therapy (ABNCT) facility based on the high-current low-energy proton beam driven by the linear accelerator at SARAF (Soreq Applied Research Accelerator Facility) incident on a windowless forced-flow liquid-lithium target, is described. The liquid-lithium target, currently in construction at Soreq NRC, will produce a neutron field suitable for the BNCT treatment of deep-seated tumor tissues, through the reaction 7Li(p,n)7Be. The liquid-lithium target is designed to overcome the major problem of solid lithium targets, namely to sustain and dissipate the power deposited by the high-intensity proton beam. Together with diseases conventionally targeted by BNCT, we propose to study the application of our setup to a novel approach in treatment of diseases associated with bacterial infections and biofilms, e.g. inflammations on implants and prosthetic devices, cystic fibrosis, infectious kidney stones. Feasibility experiments evaluating the boron neutron capture effectiveness on bacteria annihilation are taking place at the Soreq nuclear reactor.

  14. High power accelerator-based boron neutron capture with a liquid lithium target and new applications to treatment of infectious diseases

    Halfon, S. [Soreq NRC, Yavne 81800 (Israel); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)], E-mail: halfon@phys.huji.ac.il; Paul, M. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Steinberg, D. [Biofilm Laboratory, Institute of Dental Sciences, Faculty of Dentistry, Hebrew University-Hadassah (Israel); Nagler, A.; Arenshtam, A.; Kijel, D. [Soreq NRC, Yavne 81800 (Israel); Polacheck, I. [Clinical Microbiology and Infectious Diseases, Hadassah-Hebrew University Medical Center (Israel); Srebnik, M. [Department of Medicinal Chemistry and Natural Products, School of Pharmacy, Hebrew University, Jerusalem 91120 (Israel)

    2009-07-15

    A new conceptual design for an accelerator-based boron neutron capture therapy (ABNCT) facility based on the high-current low-energy proton beam driven by the linear accelerator at SARAF (Soreq Applied Research Accelerator Facility) incident on a windowless forced-flow liquid-lithium target, is described. The liquid-lithium target, currently in construction at Soreq NRC, will produce a neutron field suitable for the BNCT treatment of deep-seated tumor tissues, through the reaction {sup 7}Li(p,n){sup 7}Be. The liquid-lithium target is designed to overcome the major problem of solid lithium targets, namely to sustain and dissipate the power deposited by the high-intensity proton beam. Together with diseases conventionally targeted by BNCT, we propose to study the application of our setup to a novel approach in treatment of diseases associated with bacterial infections and biofilms, e.g. inflammations on implants and prosthetic devices, cystic fibrosis, infectious kidney stones. Feasibility experiments evaluating the boron neutron capture effectiveness on bacteria annihilation are taking place at the Soreq nuclear reactor.

  15. Cold neutron source at CMRR

    As an effective means to study structure of many materials and law of microscopic movements on atomic or molecular scale, neutron scattering technique is paid more and more attention by many countries. To promote its development in China, a set of advanced Neutron Scattering Experimental Facilities (NSEF) will be installed at China Mianyang Research Reactor (CMRR), currently under construction. The cold neutron source (CNS) on CMRR, one of the most important components of NSEF, is of vertical thermosiphon type, and uses single-phase liquid hydrogen moderator. Nice working capacity and safety are the benefit features of CNS on CMRR. Cooling helium from refrigerator removes the total heat load from CNS in the heat exchanger. In this paper, the in-pile parts, parameters and safety features of CNS are given in detail. At the same time, the utilization of the CNS is briefly described. (author)

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

    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

  17. Californium-252 Neutron Sources for Medical Applications

    Californium-252 neutron sources are being prepared to investigate the value of this radionuclide in diagnosing and treating diseases. A source resembling a cell-loaded radium needle was developed for neutron therapy. Since therapy needles are normally implanted in the body, very conservative design criteria were established to prevent leakage of radioactive. Methods are being developed to prepare very intense californium sources that could be used eventually for neutron radiography and for diagnosis by neutron activation analysis. This paper discusses these methods

  18. Outline of spallation neutron source engineering

    Slow neutrons such as cold and thermal neutrons are unique probes which can determine structures and dynamics of condensed matter in atomic scale. The neutron scattering technique is indispensable not only for basic sciences such as condensed matter research and life science, but also for basic industrial technology in 21 century. It is believed that to survive in the science-technology competition in 21 century would be almost impossible without neutron scattering. However, the intensity of neutrons presently available is much lower than synchrotron radiation sources, etc. Thus, R and D of intense neutron sources become most important. The High-Intensity Proton Accelerator Project is now being promoted jointly by Japan Atomic Energy Research Institute and High Energy Accelerator Research Organization, but there has so far been no good text which covers all the aspects of pulsed spallation neutron sources. The present review was prepare aiming at giving a better understanding on pulsed spallation neutron sources not only to neutron source researchers but also more widely to neutron scattering researchers and accelerator scientists in this field. The contents involve, starting from what is neutron scattering and what neutrons are necessary for neutron scattering, what is the spallation reaction, how to produce neutrons required for neutron scattering more efficiently, target-moderator-reflector neutronics and its engineering, shielding, target station, material issues, etc. The author have engaged in R and D of pulsed apallation neutron sources and neutron scattering research using them over 30 years. The present review is prepared based on the author's experiences with useful information obtained through ICANS collaboration and recent data from the JSNS (Japanese Spallation Neutron Source) design team. (author)

  19. Outline of spallation neutron source engineering

    Watanabe, Noboru [Center for Neutron Science, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai, Ibaraki (Japan)

    2001-01-01

    Slow neutrons such as cold and thermal neutrons are unique probes which can determine structures and dynamics of condensed matter in atomic scale. The neutron scattering technique is indispensable not only for basic sciences such as condensed matter research and life science, but also for basic industrial technology in 21 century. It is believed that to survive in the science-technology competition in 21 century would be almost impossible without neutron scattering. However, the intensity of neutrons presently available is much lower than synchrotron radiation sources, etc. Thus, R and D of intense neutron sources become most important. The High-Intensity Proton Accelerator Project is now being promoted jointly by Japan Atomic Energy Research Institute and High Energy Accelerator Research Organization, but there has so far been no good text which covers all the aspects of pulsed spallation neutron sources. The present review was prepare aiming at giving a better understanding on pulsed spallation neutron sources not only to neutron source researchers but also more widely to neutron scattering researchers and accelerator scientists in this field. The contents involve, starting from what is neutron scattering and what neutrons are necessary for neutron scattering, what is the spallation reaction, how to produce neutrons required for neutron scattering more efficiently, target-moderator-reflector neutronics and its engineering, shielding, target station, material issues, etc. The author have engaged in R and D of pulsed apallation neutron sources and neutron scattering research using them over 30 years. The present review is prepared based on the author's experiences with useful information obtained through ICANS collaboration and recent data from the JSNS (Japanese Spallation Neutron Source) design team. (author)

  20. Different spectra with the same neutron source

    Using as source term the spectrum of a 239Pu-Be source several neutron spectra have been calculated using Monte Carlo methods. The source term was located in the centre of spherical moderators made of light water, heavy water and polyethylene of different diameters. Also a 239Pu-Be source was used to measure its neutron spectrum, bare and moderated by water. The neutron spectra were measured at 100 cm with a Bonner spheres spectrometer. Monte Carlo calculations were used to calculate the neutron spectra of bare and water-moderated spectra that were compared with those measured with the spectrometer. Resulting spectra are similar to those found in power plants with PWR, BWR and Candu nuclear reactors. Beside the spectra the dosimetric features were determined. Using moderators and a single neutron source can be produced neutron spectra alike those found in workplaces, this neutron fields can be utilized to calibrate neutron dosimeters and area monitors. (Author)

  1. Final report of the IAEA advisory group meeting on accelerator-based nuclear analytical techniques for characterization and source identification of aerosol particles

    The field of aerosol characterization and source identification covers a wide range of scientific and technical activities in many institutions, in both developed and developing countries. This field includes research and applications on urban air pollution, source apportionment of suspended particulate matter, radioactive aerosol particles, organic compounds carried on particulate matter, elemental characterization of particles, and other areas. The subject of this AGM focused on the use of accelerator-based nuclear analytical techniques for determination of elemental composition of particles (by either bulk or single particle analysis) and the use of accumulated knowledge for source identification

  2. Destructive analysis of neutron sources

    Fuel-liner reactions in Pu--Be neutron sources were examined. The source is contained in an outer jacket of 304 stainless steel and an inner Ta container incorporating a TIG welded Ta plug. Small cracks were observed in some of the outer stainless steel containers as well as in some of the tantalum inner liners. Major cracking was observed as well as penetration of the reaction product through the tantalum sidewalls in two sources. High temperatures aided and accelerated the degradation and ultimate failure of the tantalum inner liner. Traces of beryllium metal as indicated from x-ray results of the fuel and large concentration gradients between tantalum and plutonium as shown in microprobe analysis were found to exist. The fuel was inhomogeneous in nature and the data suggest the possibility of tantalum-beryllium compounds, free unreacted plutonium, and potentially a ternary phase of tantalum, beryllium, plutonium as being present in the fuel

  3. The advanced neutron source (ANS) project

    The Advanced Neutron Source (ANS) is a new user experimental facility for neutron research planned at Oak Ridge. The centerpiece of the facility will be a steady-state source of neutrons from a reactor of unprecedented flux. In addition, extensive and comprehensive equipment and facilities for neutron research will be included. The scientific fields to be served include neutron scattering with cold, thermal, and hot neutrons (the most important scientific justification for the project); engineering materials irradiation; isotope production (including transuranium isotopes); materials analysis; and nuclear science

  4. Advanced Neutron Source operating philosophy

    An operating philosophy and operations cost estimate were prepared to support the Conceptual Design Report for the Advanced Neutron Source (ANS), a new research reactor planned for the Oak Ridge National Laboratory (ORNL). The operating philosophy was part of the initial effort of the ANS Human Factors Program, was integrated into the conceptual design, and addressed operational issues such as remote vs local operation; control room layout and responsibility issues; role of the operator; simulation and training; staffing levels; and plant computer systems. This paper will report on the overall plans and purpose for the operations work, the results of the work done for conceptual design, and plans for future effort

  5. Advanced Neutron Source (ANS) Project

    This report covers the progress made in 1993 in the following sections: (1) project management; (2) research and development; (3) design and (4) safety. The section on research and development covers the following: (1) reactor core development; (2) fuel development; (3) corrosion loop tests and analysis; (4) thermal-hydraulic loop tests; (5) reactor control and shutdown concepts; (6) critical and subcritical experiments; (7) material data, structure tests, and analysis; (8) cold source development; (9) beam tube, guide, and instrument development; (10) neutron transport and shielding; (11) I and C research and development; and (12) facility concepts

  6. Proposed pulsed neutron source for radiotherapy and radiography

    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

  7. High-flux fusion neutron source for transmutation of fission products

    Transmutation of long-lived fission products is often referred to as a crucial step toward harmonized Self-Consistent Nuclear Energy System. The feasibility of their incineration is determined by available neutron excess in the nuclear energy system as a whole and appropriate transmutation environment (neutron spectra and flux) in a dedicated transmuter. The present paper highlights the remarkable transmutation environment of Fusion Neutron Source with ITER-like plasma parameters in approaching the transmutation characteristics which are superior to that of fission and accelerator based transmuters. Quantitative example of zirconium and cesium transmutation is addressed. (author)

  8. A mobile D-T neutron source for neutron radiography

    There has been an increasing need for a reliable and high flux and monoenergetic neutron source facility for radiographic applications both in basic research and industry. The neutron generator based on D-T reaction is a prolific source of 14 MeV neutrons which can be suitably moderated for providing a collimated beam of thermal neutrons. The main features of the D-T generator incorporating major changes in size reduction for converting it into a mobile unit is discussed. Structural details regarding ion source, accelerator design and tritium target system is highlighted. A built-in deuterium gas supply unit provides uninterrupted deuteron beam for on-line measurements. A neutron yield of 10E12 n/sec would ensure that thermal neutron radiography as well as activation analysis could be considered. The salient features of the different subsystems and their design as well as operational characteristics are presented. (author)

  9. Neutronic conceptual design of the ETRR-2 cold neutron source

    The conceptual neutronic design of the cold neutron source (CNS) for the Egyptian second research reactor (ETRR-2) was carried out using the MCNP code. A parametric analysis was also performed to choose the type and geometry of the moderator and the required CNS dimensions to maximize the cold neutron production. The moderator cell is a spherical annulus containing liquid hydrogen. The cold neutron gain and brightness are calculated together with the nuclear heat load of the CNS. The effects of void fraction in the moderator cell and the ortho:para ratios on cold neutron gain were calculated. (orig.)

  10. Intense neutron sources for cancer treatment

    Significant progress has been made in the development of small, solid-target, pulsed neutron sources for nuclear weapons applications. The feasibility of using this type of neutron source for cancer treatment is discussed. Plans for fabrication and testing of such a source is briefly described

  11. Cryogenic refrigeration for cold neutron sources

    Neutron moderation by means of a fluid at cryogenic temperature is a very interesting way to obtain cold neutrons. Today, a number of nuclear research reactors are using this technology. This paper deals with thermodynamics and technology which are used for cooling Cold Neutron Sources

  12. Slow neutron leakage spectra from spallation neutron sources

    An efficient technique is described for Monte Carlo simulation of neutron beam spectra from target-moderator-reflector assemblies typical of pulsed spallation neutron sources. The technique involves the scoring of the transport-theoretical probability that a neutron will emerge from the moderator surface in the direction of interest, at each collision. An angle-biasing probability is also introduced which further enhances efficiency in simple problems. These modifications were introduced into the VIM low energy neutron transport code, representing the spatial and energy distributions of the source neutrons approximately as those of evaporation neutrons generated through the spallation process by protons of various energies. The intensity of slow neutrons leaking from various reflected moderators was studied for various neutron source arrangements. These include computations relating to early measurements on a mockup-assembly, a brief survey of moderator materials and sizes, and a survey of the effects of varying source and moderator configurations with a practical, liquid metal cooled uranium source Wing and slab, i.e., tangential and radial moderator arrangements, and Be vs CH2 reflectors are compared. Results are also presented for several complicated geometries which more closely represent realistic arrangements for a practical source, and for a subcritical fission multiplier such as might be driven by an electron linac. An adaptation of the code was developed to enable time dependent calculations, and investigated the effects of the reflector, decoupling and void liner materials on the pulse shape

  13. PGNAA neutron source moderation setup optimization

    Zhang, Jinzhao

    2013-01-01

    Monte Carlo simulations were carried out to design a prompt {\\gamma}-ray neutron activation analysis (PGNAA) thermal neutron output setup using MCNP5 computer code. In these simulations the moderator materials, reflective materials and structure of the PGNAA 252Cf neutrons of thermal neutron output setup were optimized. Results of the calcuations revealed that the thin layer paraffin and the thick layer of heavy water moderated effect is best for 252Cf neutrons spectrum. The new design compared with the conventional neutron source design, the thermal neutron flux and rate were increased by 3.02 times and 3.27 times. Results indicate that the use of this design should increase the neutron flux of prompt gamma-ray neutron activation analysis significantly.

  14. Neutronic studies of the coupled moderators for spallation neutron sources

    Yin Wen; Liang Jiu-Qing

    2005-01-01

    We investigate the neutronic performance of coupled moderators to be implemented in spallation neutron sources by Monte-Carlo simulation and give the slow neutron spectra for the cold and thermal moderators. CH4 moderator can provide slow neutrons with highly desirable characteristics and will be used in low-power spallation neutron soureces. The slow neutron intensity extracted from different angles has been calculated. The capability of moderation of liquid H2 is lower than H2O and liquid CH4 due to lower atomic number density of hydrogen but we can compensate for this disadvantage by using a premoderator. The H2O premoderator of 2cm thickness can reduce the heat deposition in the cold moderator by about 33% without spoiling the neutron pulse.

  15. Materials and neutronic research at the Low Energy Neutron Source

    Baxter, David V.

    2016-04-01

    In the decade since the Low Energy Neutron Source (LENS) at Indiana University Center for Exploration of Energy and Matter (CEEM) produced its first neutrons, the facility has made important contributions to the international neutron scattering community. LENS employs a 13MeV proton beam at up to 4kW beam power onto one of two Be targets to produce neutrons for research in fields ranging from radiation effects in electronics to studies of the structure of fluids confined in nanoporous materials. The neutron source design at the heart of LENS facilitates relatively rapid hands-on access to most of its components which provides a foundation for a research program in experimental neutronics and affords numerous opportunities for novel educational experiences. We describe in some detail a number of the unique capabilities of this facility.

  16. Neutron Sources for Standard-Based Testing

    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.

  17. Neutron spin echo spectroscopy on the spallation neutron source

    An investigation has been made into the practicability of combining the neutron spin echo and time-of-flight techniques on the Rutherford Laboratory Spallation Neutron Source. Preliminary specifications are presented for a quasielastic instrument with an energy resolution down to approximately 10 neV and an inelastic spectrometer for measuring excitation widths approximately 1 μ eV. (author)

  18. Nested Focusing Optics for Compact Neutron Sources

    Nabors, Sammy A.

    2015-01-01

    NASA's Marshall Space Flight Center, the Massachusetts Institute of Technology (MIT), and the University of Alabama Huntsville (UAH) have developed novel neutron grazing incidence optics for use with small-scale portable neutron generators. The technology was developed to enable the use of commercially available neutron generators for applications requiring high flux densities, including high performance imaging and analysis. Nested grazing incidence mirror optics, with high collection efficiency, are used to produce divergent, parallel, or convergent neutron beams. Ray tracing simulations of the system (with source-object separation of 10m for 5 meV neutrons) show nearly an order of magnitude neutron flux increase on a 1-mm diameter object. The technology is a result of joint development efforts between NASA and MIT researchers seeking to maximize neutron flux from diffuse sources for imaging and testing applications.

  19. International workshop on cold neutron sources

    Russell, G.J.; West, C.D. (comps.) (Los Alamos National Lab., NM (United States))

    1991-08-01

    The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5--8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people from seven countries attended. Because the meeting was the first of its kind in over forty years, much time was spent acquainting participants with past and planned activities at reactor and spallation facilities worldwide. As a result, the meeting had more of a conference flavor than one of a workshop. The general topics covered at the workshop included: Criteria for cold source design; neutronic predictions and performance; energy deposition and removal; engineering design, fabrication, and operation; material properties; radiation damage; instrumentation; safety; existing cold sources; and future cold sources.

  20. International workshop on cold neutron sources

    The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5--8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people from seven countries attended. Because the meeting was the first of its kind in over forty years, much time was spent acquainting participants with past and planned activities at reactor and spallation facilities worldwide. As a result, the meeting had more of a conference flavor than one of a workshop. The general topics covered at the workshop included: Criteria for cold source design; neutronic predictions and performance; energy deposition and removal; engineering design, fabrication, and operation; material properties; radiation damage; instrumentation; safety; existing cold sources; and future cold sources

  1. Neutron scattering instrumentation for biology at spallation neutron sources

    Pynn, R. [Los Alamos National Laboratory, NM (United States)

    1994-12-31

    Conventional wisdom holds that since biological entities are large, they must be studied with cold neutrons, a domain in which reactor sources of neutrons are often supposed to be pre-eminent. In fact, the current generation of pulsed spallation neutron sources, such as LANSCE at Los Alamos and ISIS in the United Kingdom, has demonstrated a capability for small angle scattering (SANS) - a typical cold- neutron application - that was not anticipated five years ago. Although no one has yet built a Laue diffractometer at a pulsed spallation source, calculations show that such an instrument would provide an exceptional capability for protein crystallography at one of the existing high-power spoliation sources. Even more exciting is the prospect of installing such spectrometers either at a next-generation, short-pulse spallation source or at a long-pulse spallation source. A recent Los Alamos study has shown that a one-megawatt, short-pulse source, which is an order of magnitude more powerful than LANSCE, could be built with today`s technology. In Europe, a preconceptual design study for a five-megawatt source is under way. Although such short-pulse sources are likely to be the wave of the future, they may not be necessary for some applications - such as Laue diffraction - which can be performed very well at a long-pulse spoliation source. Recently, it has been argued by Mezei that a facility that combines a short-pulse spallation source similar to LANSCE, with a one-megawatt, long-pulse spallation source would provide a cost-effective solution to the global shortage of neutrons for research. The basis for this assertion as well as the performance of some existing neutron spectrometers at short-pulse sources will be examined in this presentation.

  2. Control circuit for a pulsed neutron source

    A pulsed neutron source is operated with a control circuit which produces neutron pulses very sharply defined with reference to time. A relatively steep rising high voltage control pulse for the ion source is produced by means of a low voltage input control pulse. Simultaneously, a control pulse is generated for a delayed quenching circuit, which quenches the high voltage control pulse for the ion source after a fixed time delay for a short time. The control voltage obtained for the ion source and for the neutron output is sharply defined as regards time. (orig.)

  3. Neutron cooling and cold-neutron sources (1962)

    Intense cold-neutron sources are useful in studying solids by the inelastic scattering of neutrons. The paper presents a general survey covering the following aspects: a) theoretical considerations put forward by various authors regarding thermalization processes at very low temperatures; b) the experiments that have been carried out in numerous laboratories with a view to comparing the different moderators that can be used; c) the cold neutron sources that have actually been produced in reactors up to the present time, and the results obtained with them. (author)

  4. Radionuclide 252Cf neutron source

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

  5. Rotating target neutron source II: progress report

    The RTNS-II Facility at Livermore was authorized in the FY76 ERDA budget. This facility will house two 4 x 1013 n/s sources of 14-MeV neutrons for materials damage experimentation. RTNS-II will be the first of DCTR's dedicated neutron source facilities. Initial operation is currently scheduled for March 1978. Engineering design of buildings and neutron sources started in March 1976 with construction scheduled to begin in August 1976. Design of the 150 mA D+ accelerators is based upon LLL experience with the MATS-III ion source and with the ICT accelerator of the RTNS-I source. Hardware design for the 50 cm, 5000 rpm tritium-in-titanium targets was guided by computer modeling of the target system now in use on RTNS-I. The final design of neutron sources and building layout will be discussed

  6. Advanced Neutron Source (ANS) Project progress report

    This report discusses the following topics on the advanced neutron source: quality assurance (QA) program; reactor core development; fuel element specification; corrosion loop tests and analyses; thermal-hydraulic loop tests; reactor control concepts; critical and subcritical experiments; material data, structural tests, and analysis; cold source development; beam tube, guide, and instrument development; hot source development; neutron transport and shielding; I ampersand C research and development; facility concepts; design; and safety

  7. Detection of Neutron Sources in Cargo Containers

    Katz, J. I.

    2007-01-01

    We investigate the problem of detecting the presence of clandestine neutron sources, such as would be produced by nuclear weapons containing plutonium, within cargo containers. Small, simple and economical semiconductor photodiode detectors affixed to the outsides of containers are capable of producing statistically robust detections of unshielded sources when their output is integrated over the durations of ocean voyages. It is possible to shield such sources with thick layers of neutron-abs...

  8. Advanced Neutron Source (ANS) Project progress report

    McBee, M.R.; Chance, C.M. (eds.) (Oak Ridge National Lab., TN (USA)); Selby, D.L.; Harrington, R.M.; Peretz, F.J. (Oak Ridge National Lab., TN (USA))

    1990-04-01

    This report discusses the following topics on the advanced neutron source: quality assurance (QA) program; reactor core development; fuel element specification; corrosion loop tests and analyses; thermal-hydraulic loop tests; reactor control concepts; critical and subcritical experiments; material data, structural tests, and analysis; cold source development; beam tube, guide, and instrument development; hot source development; neutron transport and shielding; I C research and development; facility concepts; design; and safety.

  9. Fission-neutrons source with fast neutron-emission timing

    Rusev, G.; Baramsai, B.; Bond, E. M.; Jandel, M.

    2016-05-01

    A neutron source with fast timing has been built to help with detector-response measurements. The source is based on the neutron emission from the spontaneous fission of 252Cf. The time is provided by registering the fission fragments in a layer of a thin scintillation film with a signal rise time of 1 ns. The scintillation light output is measured by two silicon photomultipliers with rise time of 0.5 ns. Overall time resolution of the source is 0.3 ns. Design of the source and test measurements using it are described. An example application of the source for determining the neutron/gamma pulse-shape discrimination by a stilbene crystal is given.

  10. Fission fragment driven neutron source

    Miller, Lowell G.; Young, Robert C.; Brugger, Robert M.

    1976-01-01

    Fissionable uranium formed into a foil is bombarded with thermal neutrons in the presence of deuterium-tritium gas. The resulting fission fragments impart energy to accelerate deuterium and tritium particles which in turn provide approximately 14 MeV neutrons by the reactions t(d,n).sup.4 He and d(t,n).sup.4 He.

  11. The University of Texas Cold Neutron Source

    Ünlü, Kenan; Ríos-Martínez, Carlos; Wehring, Bernard W.

    1994-12-01

    A cold neutron source has been designed, constructed, and tested by the Nuclear Engineering Teaching Laboratory (NETL) at The University of Texas at Austin. The Texas Cold Neutron Source (TCNS) is located in one of the beam ports of the NETL 1-MW TRIGA Mark II research reactor. The main components of the TCNS are a cooled moderator, a heat pipe, a cryogenic refrigerator, and a neutron guide. 80 ml of mesitylene moderator are maintained at about 30 K in a chamber within the reactor graphite reflector by the heat pipe and cryogenic refrigerator. The heat pipe is a 3-m long aluminum tube that contains neon as the working fluid. The cold neutrons obtained from the moderator are transported by a curved 6-m long neutron guide. This neutron guide has a radius of curvature of 300 m, a 50 × 15 mm cross-section, 58Ni coating, and is separated into three channels. The TCNS will provide a low-background subthermal neutron beam for neutron capture and scattering research. After the installation of the external portion of the neutron guide, a neutron focusing system and a Prompt Gamma Activation Analysis facility will be set up at the TCNS.

  12. Neutron source structure for nuclear reactors

    Purpose: To improve the compatibility between metal beryllium forming a neutron source and a metal cladding material at a high temperature. Constitution: An intermediate layer made of silicon or silicone-beryllium alloy is put between metal beryllium forming a neutron source and a metal cladding material containing the metal beryllium in a tightly sealed manner. By the disposition of the intermediate layer, the compatibility between the metal beryllium and the metal cladding material is improved, by which the neutron source can be operated satisfactorily over a long time use at a high temperature of 500 - 7000C. (Moriyama, K.)

  13. Pulsed neutron source and instruments at neutron facility

    Teshigawara, Makoto; Aizawa, Kazuya; Suzuki, Jun-ichi; Morii, Yukio; Watanabe, Noboru [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    We report the results of design studies on the optimal target shape, target - moderator coupling, optimal layout of moderators, and neutron instruments for a next generation pulsed spallation source in JAERI. The source utilizes a projected high-intensity proton accelerator (linac: 1.5 GeV, {approx}8 MW in total beam power, compressor ring: {approx}5 MW). We discuss the target neutronics, moderators and their layout. The sources is designed to have at least 30 beam lines equipped with more than 40 instruments, which are selected tentatively to the present knowledge. (author)

  14. Modeling a neutron-rich nuclei source

    The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron-rich nuclei based on the neutron-induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (orig.)

  15. Modeling a neutron rich nuclei source

    The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron rich nuclei based on the neutron induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (authors)

  16. Cryogenic hydrogen circulation system of neutron source

    Cold neutron sources of reactors and spallation neutron sources are classic high flux neutron sources in operation all over the world. Cryogenic fluids such as supercritical or supercooled hydrogen are commonly selected as a moderator to absorb the nuclear heating from proton beams. By comparing supercritical hydrogen circulation systems and supercooled hydrogen circulation systems, the merits and drawbacks in both systems are summarized. When supercritical hydrogen circulates as the moderator, severe pressure fluctuations caused by temperature changes will occur. The pressure control system used to balance the system pressure, which consists of a heater as an active controller for thermal compensation and an accumulator as a passive volume controller, is preliminarily studied. The results may provide guidelines for design and operation of other cryogenic hydrogen system for neutron sources under construction

  17. Status report on the SIN neutron source

    The present status is as follows: injector II is under construction, improvement of the proton channel for high current operation is in the design stage, and the spallation neutron source design is progressing

  18. High Brightness Neutron Source for Radiography

    Cremer, J. T.; Piestrup, Melvin, A.; Gary, Charles, K.; Harris, Jack, L. Williams, David, J.; Jones, Glenn, E.; Vainionpaa, J. , H.; Fuller, Michael, J.; Rothbart, George, H.; Kwan, J., W.; Ludewigt, B., A.; Gough, R.., A..; Reijonen, Jani; Leung, Ka-Ngo

    2008-12-08

    This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

  19. Neutron shielding for a 252 Cf source

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

  20. Future opportunities with pulsed neutron sources

    Taylor, A.D. [Rutherford Appleton Lab., Chilton (United Kingdom)

    1996-05-01

    ISIS is the world`s most powerful pulsed spallation source and in the past ten years has demonstrated the scientific potential of accelerator-driven pulsed neutron sources in fields as diverse as physics, earth sciences, chemistry, materials science, engineering and biology. The Japan Hadron Project gives the opportunity to build on this development and to further realize the potential of neutrons as a microscopic probe of the condensed state. (author)

  1. Targets for neutron beam spallation sources

    The meeting on Targets for Neutron Beam Spallation Sources held at the Institut fuer Festkoerperforschung at KFA Juelich on June 11 and 12, 1979 was planned as an informal get-together for scientists involved in the planning, design and future use of spallation neutron sources in Europe. These proceedings contain the papers contributed to this meeting. For further information see hints under relevant topics. (orig./FKS)

  2. Rietveld refinement with time-of-flight powder diffraction data from pulsed neutron sources

    The recent development of accelerator-based pulsed neutron sources has led to the widespread use of the time-of-flight technique for neutron powder diffraction. The properties of the pulsed source make possible unusually high resolution over a wide range of d spacings, high count rates, and the ability to collect complete data at fixed scattering angles. The peak shape and other instrument characteristics can be accurately modelled, which make Rietveld refinement possible for complex structures. In this paper we briefly review the development of the Rietveld method for time-of-flight diffraction data from pulsed neutron sources and discuss the latest developments in high resolution instrumentation and advanced Rietveld analysis methods. 50 refs., 12 figs., 14 tabs

  3. Neutronics of a D-Li neutron source: An overview

    The importance of having a high energy (14 MeV) neutron source for fusion materials testing is widely recognized. The availability of a test volume with easy accessibility, with a radiation environment similar to the one expected for a fusion reactor, and with dimensions large enough to accommodate several small samples or a small blanket mock-up are requirements impossible to meet with the existing reactors and irradiation facilities. A D-Li neutron source meets the above mentioned requirements and can be built today with well known technology. This paper describes some relevant topics related to beam target configuration, neutron flux spectrum, and nuclear responses for a D-Li neutron source. The target-beam configuration is analyzed for different beam cross sectional areas and trade-offs between the area of the beam and related quantities such as available volume for testing, peak fluxes, and flux or nuclear responses gradient are presented. The conclusion is that the D-Li neutron source has the necessary characteristics to be the option of choice for IFMIF

  4. A telescope for monitoring fast neutron sources

    In the framework of nuclear waste management, highly radiotoxic long-lived fission products and minor actinides are planned to be transmuted in a sub-critical reactor coupled with an intense external neutron source. The latter source would be created by a high-energy proton beam hitting a high atomic number target. Such a new system, termed an accelerator-driven system (ADS), requires on-line and robust reactivity monitoring. The ratio between the beam current delivered by the accelerator and the reactor power level, or core neutron flux, is the basis of one method which could give access to a core reactivity change. In order to test reactivity measurement technique, some experimental programs use 14-MeV neutrons originating from the interaction of a deuteron beam with a tritium target as an external neutron source. In this case, the target tritium consumption over time precludes use of the beam current for reactivity monitoring and the external neutron source intensity must be monitored directly. A range telescope has been developed for this purpose, consisting of the assembly of a hydrogenous neutron converter and three silicon stages where the recoiling protons are detected. In this article, the performances of such a telescope are presented and compared to Monte-Carlo simulations

  5. Neutron science opportunities at pulsed spallation neutron sources

    Using the IPNS Upgrade plan developed at Argonne National Laboratory as a worked example of the design of a pulsed spallation neutron source, this paper explores some of the scientific applications of an advanced facility for materials science studies and the instrumentation for those purposes

  6. Superconducting cyclotron: neutron source for therapy

    A neutron source for medical therapy purposes is described. The cyclotron consists of: an iron metal housing acting as a magnetic yoke, magnetic shield, radiation shield, and vacuum vessel; a pair of superconducting coils mounted in a cavity in the housing, the coils being cooled to superconducting temperatures; an ion orbiting region defined by pairs of sectoral-shaped rf electrode structures focusing flutter poles mounted in the intense magnetic field between coils; a source of ions; an ion target to produce neutrons; a channel formed in the iron housing from the target to the exterior for passage of the beam of neutrons formed at the target, the channel acting as a beam collimator; and a mounting structure for movably mounting the cyclotron and target such that the neutron beam produced can be employed at more than one position

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

    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

  8. Iterative Reconstruction of Coded Source Neutron Radiographs

    Santos-Villalobos, Hector J [ORNL; Bingham, Philip R [ORNL; Gregor, Jens [University of Tennessee, Knoxville (UTK)

    2012-01-01

    Use of a coded source facilitates high-resolution neutron imaging but requires that the radiographic data be deconvolved. In this paper, we compare direct deconvolution with two different iterative algorithms, namely, one based on direct deconvolution embedded in an MLE-like framework and one based on a geometric model of the neutron beam and a least squares formulation of the inverse imaging problem.

  9. Concrete enclosure to shield a neutron source

    Villagrana M, L. E.; Rivera P, E.; De Leon M, H. A.; Soto B, T. G.; Hernandez D, V. M.; Vega C, H. R., E-mail: emmanuelvillagrana@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico)

    2012-10-15

    In the aim to design a shielding for a {sup 239}PuBe isotopic neutron source several Monte Carlo calculations were carried out using MCNP5 code. First, a point-like source was modeled in vacuum and the neutron spectrum and the ambient dose equivalent were calculated at several distances ranging from 5 up to 150 cm, these calculations were repeated including air, and a 1 x 1 x 1 m{sup 3} enclosure that was shielded with 5, 15, 20, 25, 30, 50 and 80 cm-thick Portland type concrete walls. At all the points located inside the enclosure neutron spectra from 10{sup -8} up 0.5 MeV were the same regardless the distance from the source showing the room-return effect, for energies larger than 0.5 MeV neutron spectra are diminished as the distance increases. Outside the enclosure it was noticed that neutron spectra becomes -softer- as the concrete thickness increases due to reduction of mean neutron energy. With the ambient dose values the attenuation curve in terms of concrete thickness was calculated. (Author)

  10. Design of intense neutron source for fusion material study and the role of universities

    Need and requirement for the intense neutron source for fusion materials study have been discussed for many years. Recently, international climate has been becoming gradually maturing to consider this problem more seriously because of the recognition of crucial importance of solving materials problems for fusion energy development. The present symposium was designed to discuss the problems associated with the intense neutron source for material irradiation studies which will have a potential for the National Institute for Fusion Science to become one of the important future research areas. The symposium comprises five sessions; first, the role of materials research in fusion development strategies was discussed followed by a brief summary of current IFMIF (International Fusion Materials Irradiation Facility) activity. Despite the pressing need for intense fusion neutron source, currently available neutron sources are reactor or accelerator based sources of which FFTF and LASREF were discussed. Then, various concepts of intense neutron source candidates were presented including ESNIT, which are currently under design by JAERI. In the fourth session, discussions were made on the study of materials with the intense neutron source from the viewpoint of materials scientists and engineers as the user of the facility. This is followed by discussions on the role of universities from the two stand points, namely, fusion irradiation studies and fusion materials development. Finally summary discussions were made by the participants, indicating important role fundamental studies in universities for the full utilization of irradiation data and the need of pure 14 MeV neutron source for fundamental studies together with the intense surrogate neutron sources. (author)

  11. THERMAL NEUTRON INTENSITIES IN SOILS IRRADIATED BY FAST NEUTRONS FROM POINT SOURCES. (R825549C054)

    Thermal-neutron fluences in soil are reported for selected fast-neutron sources, selected soil types, and selected irradiation geometries. Sources include 14 MeV neutrons from accelerators, neutrons from spontaneously fissioning 252Cf, and neutrons produced from alp...

  12. The cold neutron source in DR 3

    A description of the cold neutron source in DR 3 is given. The moderator of the cold neutron source is supercritical hydrogen at about 30degK and 15 bar abs. The necessary cooling capacity is supplied by two Philips Stirling B20 cryogenerators. The hydrogen is circulated between the cryogenerators and the in-pile moderator chamber by small fans. The safety of the facility is based on the use of triple containment preventing contact between hydrogen and air. The triple containment is achieved by enclosing the high vacuum system, surrounging the hydrogen system, in a helium blanket. The achieved spectrum of the thermal neutron flux and the gain factor are given as well as the experience from more than 5 years of operation. Finally some work on extension of the facility to operate two cold sources is reported. (author)

  13. Iterative Reconstruction of Coded Source Neutron Radiographs

    Santos-Villalobos, Hector J [ORNL; Bingham, Philip R [ORNL; Gregor, Jens [University of Tennessee, Knoxville (UTK)

    2013-01-01

    Use of a coded source facilitates high-resolution neutron imaging through magnifications but requires that the radiographic data be deconvolved. A comparison of direct deconvolution with two different iterative algorithms has been performed. One iterative algorithm is based on a maximum likelihood estimation (MLE)-like framework and the second is based on a geometric model of the neutron beam within a least squares formulation of the inverse imaging problem. Simulated data for both uniform and Gaussian shaped source distributions was used for testing to understand the impact of non-uniformities present in neutron beam distributions on the reconstructed images. Results indicate that the model based reconstruction method will match resolution and improve on contrast over convolution methods in the presence of non-uniform sources. Additionally, the model based iterative algorithm provides direct calculation of quantitative transmission values while the convolution based methods must be normalized base on known values.

  14. 10 CFR 39.55 - Tritium neutron generator target sources.

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Tritium neutron generator target sources. 39.55 Section 39... Equipment § 39.55 Tritium neutron generator target sources. (a) Use of a tritium neutron generator target...) Use of a tritium neutron generator target source, containing quantities exceeding 1,110 GBg or in...

  15. Development of cold neutron source

    The purpose of this study is to develop the CNS facility in Hanaro to extend the scope of the neutron utilization and to carry out the works impossible by thermal neutrons. According to the project schedule, the establishment of the CNS concept and the basic design are performed in the phase 1, and the elementary technologies for basic design will be developed in the phase 2. Finally in the phase 3, the design of CNS will be completed, and the fabrication, the installation will be ended and then the development plan of spectrometers will be decided to establish the foothold to carry out the basic researches. This study is aimed to produce the design data and utilize them in the future basic and detail design, which include the estimation and the measurement of the heat load, the code development for the design of the in pile assembly and the heat removal system, the measurement of the shape of the CN hole, the performance test of thermosiphon and the concept of the general layout of the whole system etc.. (author)

  16. Development of cold neutron source

    Choi, Chang Oong; Cho, M. S.; Park, K. N. and others

    1999-05-01

    The purpose of this study is to develop the CNS facility in Hanaro to extend the scope of the neutron utilization and to carry out the works impossible by thermal neutrons. According to the project schedule, the establishment of the CNS concept and the basic design are performed in the phase 1, and the elementary technologies for basic design will be developed in the phase 2. Finally in the phase 3, the design of CNS will be completed, and the fabrication, the installation will be ended and then the development plan of spectrometers will be decided to establish the foothold to carry out the basic researches. This study is aimed to produce the design data and utilize them in the future basic and detail design, which include the estimation and the measurement of the heat load, the code development for the design of the in pile assembly and the heat removal system, the measurement of the shape of the CN hole, the performance test of thermosiphon and the concept of the general layout of the whole system etc.. (author)

  17. Resolution in deep inelastic neutron scattering using pulsed neutron sources

    The principle components of the resolution function for deep inelastic neutron scattering experiments on pulsed neutron sources have been calculated directly in atomic momentum space. Analytical expressions for the relative contributions from the energy, angular and time resolutions are presented for both direct and indirect geometry spectrometers. The general trend in the behaviour of the resolution as a function of neutron energy and atomic mass is presented, and the results of numerical calculations for recoil scattering from hydrogen, helium and beryllium using the ISIS spectrometers HET and eVS, are given. It is shown that the resolution difference between HET and eVS is significantly reduced when compared in atomic momentum space rather than in energy space. Moreover, the contribution from the angular resolution term is only significant for atomic masses <4 au. (author)

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

    Matsumoto, T

    2003-01-01

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

  19. Neutron source strength monitors for ITER

    There are several goals for the neutron source strength monitor system for the International Thermonuclear Experimental Reactor (ITER). Desired is a stable, reliable, time-dependent neutron detection system which exhibits a wide dynamic range and broad energy response to incident neutrons while being insensitive to gamma rays and having low noise characteristics in a harsh reactor environment. This system should be able to absolutely calibrated in-situ using various neutron sources. An array of proportional counters of varying sensitivities is proposed along with the most promising possible locations. One proposed location is in the pre-shields of the neutron camera collimators which would allow an integrated design of neutron systems with good detector access. As part of an ongoing conceptual design for this system, the detector-specific issues of dynamic range, performance monitoring, and sensitivity will be presented. The location options of the array will be discussed and most importantly, the calibration issues associated with a heavily shielded vessel will be presented

  20. Neutron source strength monitors for ITER

    Barnes, C.W. [Sandia National Labs., Albuquerque, NM (United States); Roquemore, A.L. [Princeton Univ., NJ (United States). Plasma Physics Lab.

    1996-05-07

    There are several goals for the neutron source strength monitor system for the International Thermonuclear Experimental Reactor (ITER). Desired is a stable, reliable, time-dependent neutron detection system which exhibits a wide dynamic range and broad energy response to incident neutrons while being insensitive to gamma rays and having low noise characteristics in a harsh reactor environment. This system should be able to absolutely calibrated in-situ using various neutron sources. An array of proportional counters of varying sensitivities is proposed along with the most promising possible locations. One proposed location is in the pre-shields of the neutron camera collimators which would allow an integrated design of neutron systems with good detector access. As part of an ongoing conceptual design for this system, the detector-specific issues of dynamic range, performance monitoring, and sensitivity will be presented. The location options of the array will be discussed and most importantly, the calibration issues associated with a heavily shielded vessel will be presented.

  1. Neutronic Design of a Cold Neutron Source with MCNP

    The neutronic design of a cold neutron source (CNS) requires the use of powerful tools to model neutron transport as accurately as possible. For this purpose, nowadays, the increase in hardware calculation power makes it possible to make use of Monte Carlo techniques, even during the design stage. For design purposes, the goal is to find the optimal combination between positioning and geometry of the moderator chamber and composition of the moderator material to produce the maximum cold neutron flux at the experimental location. Close to the optimum balance, the influence of each of these parameters on the cold flux can be expected to be about 1-5%. These small effects must be discriminated from statistical errors without a strong increase of the calculation time. A short description of the calculation line, leading to a fast and reliable method to perform these optimization calculations with low statistical errors and times compatible with a design schedule is presented. Several parametric analyses of the design variables are presented in order to show how this calculation methodology works and how consistent their results are. The analysis was done during the design of the replacement research reactor (RRR) CNS for the Australian Nuclear Science and Technology Organisation (ANSTO). As a conclusion to the paper, we demonstrate the possibility to apply Monte Carlo techniques in a design project framework to obtain an optimized CNS neutronic design. (author)

  2. Fast neutron capture with a white neutron source

    A system has been developed at the Los Alamos National Laboratory to measure gamma-rays following fast neutron reactions. The neutron beam is produced by bombarding a thick tantalum target with the 800 MeV proton beam from the LAMPF accelerator. Incident neutron energies, from 1 to over 200 MeV, are determined by their times of flight over a 7.6-m flight path. The gamma-rays are detected in five 7.6 x 7.6-cm cylindrical bismuth germanate (BGO) detectors which span an angular range from 450 to 1450 in the reaction plane. With this system it is possible to simultaneously measure the cross section and angular distribution of gamma-rays as a function of neutron energy. The results for the cross section of the 12C(n,n'γ=4.44 MeV) reaction at 900 and 1250 show good agreement with previous measurements while the complete angular distributions show the need for a large a4 coefficient which was not previously observed. Preliminary results for the 12C(n,n'γ=15.1 MeV) reaction have also been obtained. The data obtained for the 40Ca(n,γ0) reaction in the region of the giant dipole resonance demonstrate the unique capabilities of this system. Future developments to the neutron source which will enhance the capabilities of the system are presented. 14 references

  3. Options for neutron scattering instruments on long pulse neutron sources

    Instrumenttion on long pulse sources can be approached either by instruments from short pulse sources and hence using mainly inverted time of flight techniques or by adopting reactor type instruments and making use of the time dependence of the source flux to enhance their performance substantially. While the first approach requires more or less single use of a beam line by one instrument, the second one allows multiple use of neutron guides, as customary on reactors and hence can make much better use of the source with gains up to 100 for time of flight spectrometers. To a certain extent, the design parameters of the source depend on which of the two approaches is chosen. (author) 8 figs., 1 tab., 16 refs

  4. Spallation neutron source RF cavity bias system

    The Spallation Neutron Source r.f. cavity bias system is described under the topic headings: bias system, r.f. cavity, cables, d.c. bias power supply, transistor regulator and control system. Calculation of 4 core 300 mm solid aluminium cable inductance, coaxial shunt frequency response and transistor regulator computed frequency response, are discussed in appendices 1-3. (U.K.)

  5. SUPERCONDUCTING LINAC FOR THE SPALLATION NEUTRON SOURCE

    The Spallation Neutron Source (SNS) linac is comprised of both normal and superconducting rf (SRF) accelerating structures. The SRF linac accelerates the beam from 186 to 1250 MeV through 117 elliptical, multi-cell niobium cavities. This paper describes the SRF linac architecture, physics design considerations, cavity commissioning, and the expected beam dynamics performance

  6. Cold moderators for pulsed neutron sources

    This paper reviews cold moderators in pulsed neutron sources and provides details of the performance of different cold moderator materials and configurations. Analytical forms are presented which describe wavelength spectra and emission time distributions. Several types of cooling arrangements used in pulsed source moderators are described. Choices of materials are surveyed. The author examines some of the radiation damage effects in cold moderators, including the phenomenon of ''burping'' in irradiated cold solid methane. 9 refs., 15 figs., 4 tabs

  7. Neutron sources in Canada - Present and future

    Dolling, G.; Lidstone, R. F.

    Canada's pre-eminent neutron source since 1957 has been the NRU reactor at Chalk River. It is unlikely to operate beyond the year 2005. In 1994, AECL prepared the case and concept for a new research reactor, the Irradiation Research Facility (IRF), to replace NRU. The IRF was developed with the dual purpose of meeting the needs of both R&D programs to support existing and advanced CANDU® designs and also of condensed matter science and materials research using extracted neutron beams. In November 1995, AECL began a pre-project engineering programme to develop the design of the facility and to begin the safety analysis and “up-front” licensing process. The dual-purpose concept continues to be pursued and the design modified, to achieve maximum performance in the most cost-effective manner. The planned neutron-beam facilities, which include a cold source and a guide hall, will greatly enhance Canada's programs of neutron-beam research and applications. The current status of the IRF design and of efforts to secure funding for the neutron-beam components will be presented.

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

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

  9. Neutron importance in source-driven systems

    A study of integral indicators of the neutron source importance in source-driven systems is carried out and their dependence on the phase-space characteristics of the neutron source is investigated in the first part of the paper. The second part is devoted to the analysis of the solution of the source-driven adjoint model, introducing different detectors as far as the spatial location and the energy is concerned. Spatial, angular and spectral effects are evidenced, solving the transport equation for a 2-dimensional x-y configuration in the multigroup SN approximation. Various definitions of the adjoint problem may be used in the interpretation of local flux measurements in source-driven subcritical systems and in the weighting procedures for the development of computational methods for transient analyses. The definition of the appropriate problem-dependent detector is still an open question and an object of discussion within the accelerator-driven system community. Some results showing the effects of different choices of the adjoint source on the effective mean neutron lifetime are illustrated. (authors)

  10. Neutronic design of a cold neutron source with MCNP

    Full text: The design of a Cold Neutron Source (CNS) is affected by several parameters. The design parameters can be divided in groups according to the magnitude that they affect: Parameters that affect the average cold neutron flux value inside the CNS cell. In this group are contained the location of the CNS and the volume of the CNS cell; Parameters that affect the cold neutron flux at an experimental location. In this group are placed the thickness of the CNS cell wall and the gaps between the CNS and the beam tube; Parameters that affect the neutron flux spectrum that enters into the beam tube. Within this group it is considered the shape and dimension of a displacer or cavity placed inside the CNS cell and the temperature and density of the moderator contained inside the CNS cell. Because each design parameters has more than one effect (sometimes opposite effects) it is necessary to evaluate its performance at an experimental location. A typical example of these opposite effects is the introduction of a cavity (or a displacer) in the CNS cell in order to increase the cold neutron current that leaves the CNS in the beam tube direction. A large volume of the cavity makes it possible that the neutrons coming from the proximity of the CNS center can enter the beam tube. The neutrons coming from the CNS center are cooler and the neutron guide will transport them more efficiently. On the other hand, a large cavity volume reduces the volume of the CNS cell, i.e., reduces the CNS capacity to moderate neutrons and it reduces the average cold neutron flux inside the moderator cell. During the design we must find the dimensions and shapes of the cavity (or displacer) and moderator cell that produces the maximum cold neutron flux at the experimental location. It is necessary during the design stage to use a powerful tool to transport the since their creation in the core conditions. The increase in the calculation capacity of new computers makes it possible to use the

  11. Evaluation of the photo-neutron source and delayed neutrons in the Syrian miniature neutron source reactor

    A mathematical model has been developed to simulate the dynamic behavior of the Syrian Miniature Neutron Source Reactor (MNSR). The model is used to assess and evaluate the core average temperature as a function of the overall reactivity load in the core on one hand. On the other hand, the model is utilized to evaluate dynamically the photo and delayed neutron effects in MNSR. The model considers relevant physical phenomena that govern the core such as reactor kinetics, reactivity feedbacks due to coolant temperature and xenon, and thermalhydraulics. Natural convection and point kinetics including the prompt jump and complete mixing approximations were employed. Peak power, reactivity core load, core outlet temperature, and other variables are predicted during self-limiting power excursions. Direct photo-neutron sources strength was dynamically evaluated for the MNSR in subcritical condition. Two different static methods were applied for comparison. In addition, measurement of the photo-neutron source was made using neutron flux monitors and neutron activation analysis technique. Results for both methods were in good agreement. Dynamics effect of the photo neutron source on reactor response to reactivity insertions was demonstrated. Photo-neutron source existence due to beryllium reflector was realized. Compared to related references, close results have been obtained. Core average temperature was studied as a function of reactivity during reactor operation and transients. An overall rough estimate of core average temperature as a function of reactivity load is presented; hence, a procedure to measure such temperature is suggested. (author)

  12. Securing the future of medical isotopes and neutron science in Canada: the Canadian Neutron Source (CNS)

    This presentation discusses establishment of the Canadian Neutron Source (CNS) that could be utilized for production of medical isotopes and neutron science in Canada. The Canadian Neutron Source would be 20 MWth research reactor optimized for delivery of medical isotopes and neutron beams for neutron science to serve both industry and the public sector. Employing existing reactor and isotope technology minimizes the risk and schedule. Neutron beams could be used in materials science research, biomedical research as well as imaging.

  13. Practical consequences for the use of a personal dosemeter for fast neutrons at high-energy accelerators based on PADC detectors exposed up to one year

    Since 1998, Paul Scherrer Institut has employed the routine use of a personal neutron dosimetry system based on chemically etched PADC (poly allyl diglycol carbonate) detectors and automatic track counting. In 2004, a new concept for individual monitoring at high-energy accelerators was implemented. In this concept the photon dosemeter of a combined photon/neutron dosemeter is evaluated monthly. The neutron dosemeter is only evaluated if the personal photon dose exceeds 2 mSv, or if the exposition period of the neutron dosemeter exceeds one year. Significant consequences for the evaluation of the neutron dosemeter in the dosimetry service were evidenced in the new concept. The wearing period of the neutron dosemeter can range from 1 to 12 months, potentially longer. Therefore, the long-term behavior of background track density and variation of response to Am-Be within 17 months was studied. The effects of 'fading' and 'aging' that influence the response of PADC detectors are determined. The application of an algorithm for neutron dose calculation takes into account long-term behavior and is described. Furthermore, repeated field calibrations were performed at the CERN-EU high-energy reference field (CERF) facility.

  14. Cold neutron source at the Budapest reactor

    The installation of a liquid hydrogen cold neutron source assembly with a single closed circuit feed by two cryogenerators and utilizing the thermosyphon principle is in progress at the reconstructed Budapest reactor. The end of the in-pile part is a nearly tangential horizontal channel with a moderator cell of 250 cm3 volume made of aluminium alloy located in a hole inside the Be-reflector. The cold neutrons will be directed to the user positions by three mirror guide tubes. (orig.)

  15. Sweden to host a new neutron source

    Anaïs Schaeffer

    2012-01-01

    The first European neutron source, currently under development, should commence operations by the end of this decade. Its aim: to produce beams of neutrons that can penetrate into the heart of matter without damaging it and reveal its secrets.   An artist's impression of what the ESS should look like in 2019. At the southern end of Sweden, a town called Lund is preparing for the arrival of the world's most powerful neutron source: the European Spallation Source (ESS). Construction is scheduled to start at the beginning of next year, and the facility is expected to become operational by 2019, when it will produce its first neutron beams. “The ESS is the result of an idea that began 20 years ago!” underlines Mats Lindroos, in charge of the ESS Accelerator Division. “Today, 17 European countries support the project, including Sweden, Denmark and Norway, who together account for 50% of the construction funding.” The ESS, whose design is al...

  16. Material selection for spallation neutron source windows

    Sordo, F. [ETSII/Universidad Politecnica de Madrid, J. Gutierrez Abascal, 2-28006 Madrid (Spain); Abanades, A. [ETSII/Universidad Politecnica de Madrid, J. Gutierrez Abascal, 2-28006 Madrid (Spain)], E-mail: abanades@etsii.upm.es; Lafuente, A.; Martinez-Val, J.M. [ETSII/Universidad Politecnica de Madrid, J. Gutierrez Abascal, 2-28006 Madrid (Spain); Perlado, M. [Instituto de Fusion Nuclear (DENIM)/ETSII/Universidad Politecnica, Madrid, J. Gutierrez Abascal, 2-28006 Madrid (Spain)

    2009-11-15

    High performance neutron sources are being proposed for many scientific and industrial applications, ranging from material studies, hybrid reactors and transmutation of nuclear wastes. In the case of transmutation of nuclear wastes, accelerator driven systems (ADS) are considered as one of the main technical options for such purpose. In ADS a high performance spallation neutron source becomes an essential element for its operation and control. This spallation source must fulfil very challenging nuclear and thermo-mechanical requirements, because of the high neutron rates needed in ADS. The material selection for this key component becomes of paramount importance, particularly the source window that separates the vacuum accelerator tube from the spallation material where the accelerated protons impinge. In this paper, an integral analysis of spallation sources is done, taking as a reference the projects in this field proposal in the framework of European projects. Our analysis and calculations show that titanium and vanadium alloys are more suitable than steel as structural material for an industrial ADS beam window, mostly due to its irradiation damage resistance.

  17. Sources of radiation from neutron stars

    Schutz, B F

    1998-01-01

    I give a brief introduction to the problem of detecting gravitational radiation from neutron stars. After a review of the mechanisms by which such stars may produce radiation, I consider the different search strategies appropriate to the different kinds of sources: isolated known pulsars, neutron stars in binaries, and unseen neutron stars. The problem of an all-sky survey for unseen stars is the most taxing one that we face in analysing data from interferometers. I describe the kinds of hierarchical methods that are now being investigated to reach the maximal sensitivity, and I suggest a replacement for standard Fourier-transform search methods that requires fewer floating-point operations for Fourier-based searches over large parameter spaces, and in addition is highly parallelizable, working just as well on a loosely coupled network of workstations as on a tightly coupled parallel computer.

  18. Design of a scattering chamber for double differential cross-section measurement with an accelerator based 14 MeV neutron generator

    The measurement of double-differential cross-sections (DDX) for the fast neutron induced charged particle reactions on fusion technology relevant structural materials are very important for estimating the level of nuclear heating, radiation damage in a reactor environment. Such reactions are induced on bombardment of fast neutrons on the first wall, structural, and blanket components of the reactor thereby leading to formation of gases (helium, hydrogen, deuterium etc.) in the bulk of materials

  19. The 'RB' Reactor as a Source of Fast Neutrons

    A study of the RB reactor as possible source of fast neutrons began in 1976 and four different version of fast neutron sources are designed up to 1990: an external neutron converter - ENC (1976), an experimental fuel channel - EFC (1982), an internal neutron converter - INC (1983), and a coupled fast-thermal core - HERBE (1990). An overview of applications and characteristics of each particular source of fast neutrons, including available irradiation space, neutron spectra and equivalent neutron and gamma dose rates is presented in the paper. Control and safety-related implications of these modifications of the reactor are emphasised. Computer codes and nuclear data libraries, used in calculations, are described. (author)

  20. Ion source requirements for pulsed spallation neutron sources

    The neutron scattering community has endorsed the need for a high- power (1 to 5 MW) accelerator-driven source of neutrons for materials research. Properly configured, the accelerator could produce very short (sub-microsecond) bursts of cold neutrons, said time structure offering advantages over the continuous flux from a reactor for a large class of experiments. The recent cancellation of the ANS reactor project has increased the urgency to develop a comprehensive strategy based on the best technological scenarios. Studies to date have built on the experience from ISIS (the 160 KW source in the UK), and call for a high-current (approx. 100 mA peak) H- source-linac combination injecting into one or more accumulator rings in which beam may be further accelerated. The 1 to 5 GeV proton beam is extracted in a single turn and brought to the target-moderator stations. The high current, high duty-factor, high brightness and high reliability required of the ion source present a very large challenge to the ion source community. A workshop held in Berkeley in October 1994, analyzed in detail the source requirements for proposed accelerator scenarios, the present performance capabilities of different H- source technologies, and identified necessary R ampersand D efforts to bridge the gap

  1. Spallation neutron source and other high intensity froton sources

    Weiren Chou

    2003-02-06

    This lecture is an introduction to the design of a spallation neutron source and other high intensity proton sources. It discusses two different approaches: linac-based and synchrotron-based. The requirements and design concepts of each approach are presented. The advantages and disadvantages are compared. A brief review of existing machines and those under construction and proposed is also given. An R&D program is included in an appendix.

  2. Studies and modeling of cold neutron sources

    With the purpose of updating knowledge in the fields of cold neutron sources, the work of this thesis has been run according to the 3 following axes. First, the gathering of specific information forming the materials of this work. This set of knowledge covers the following fields: cold neutron, cross-sections for the different cold moderators, flux slowing down, different measurements of the cold flux and finally, issues in the thermal analysis of the problem. Secondly, the study and development of suitable computation tools. After an analysis of the problem, several tools have been planed, implemented and tested in the 3-dimensional radiation transport code Tripoli-4. In particular, a module of uncoupling, integrated in the official version of Tripoli-4, can perform Monte-Carlo parametric studies with a spare factor of Cpu time fetching 50 times. A module of coupling, simulating neutron guides, has also been developed and implemented in the Monte-Carlo code McStas. Thirdly, achieving a complete study for the validation of the installed calculation chain. These studies focus on 3 cold sources currently functioning: SP1 from Orphee reactor and 2 other sources (SFH and SFV) from the HFR at the Laue Langevin Institute. These studies give examples of problems and methods for the design of future cold sources

  3. Crystal Driven Neutron Source: A New Paradigm for Miniature Neutron Sources

    Neutron interrogation techniques have specific advantages for detection of hidden, shielded, or buried threats over other detection modalities in that neutrons readily penetrate most materials providing backscattered gammas indicative of the elemental composition of the potential threat. Such techniques have broad application to military and homeland security needs. Present neutron sources and interrogation systems are expensive and relatively bulky, thereby making widespread use of this technique impractical. Development of a compact, high intensity crystal driven neutron source is described. The crystal driven neutron source approach has been previously demonstrated using pyroelectric crystals that generate extremely high voltages when thermal cycled. Placement of a sharpened needle on the positively polarized surface of the pyroelectric crystal results in sufficient field intensification to field ionize background deuterium molecules in a test chamber, and subsequently accelerate the ions to energies in excess of ∼100 keV, sufficient for either D-D or D-T fusion reactions with appropriate target materials. Further increase in ion beam current can be achieved through optimization of crystal thermal ramping, ion source and crystal accelerator configuration. The advantage of such a system is the compact size along with elimination of large, high voltage power supplies. A novel implementation discussed incorporates an independently controlled ion source in order to provide pulsed neutron operation having microsecond pulse width.

  4. Crystal Driven Neutron Source: A New Paradigm for Miniature Neutron Sources

    Tang, V.; Morse, J.; Meyer, G.; Falabella, S.; Guethlein, G.; Kerr, P.; Park, H. G.; Rusnak, B.; Sampayan, S.; Schmid, G.; Spadaccini, C.; Wang, L.

    2009-03-01

    Neutron interrogation techniques have specific advantages for detection of hidden, shielded, or buried threats over other detection modalities in that neutrons readily penetrate most materials providing backscattered gammas indicative of the elemental composition of the potential threat. Such techniques have broad application to military and homeland security needs. Present neutron sources and interrogation systems are expensive and relatively bulky, thereby making widespread use of this technique impractical. Development of a compact, high intensity crystal driven neutron source is described. The crystal driven neutron source approach has been previously demonstrated using pyroelectric crystals that generate extremely high voltages when thermal cycled [1-4]. Placement of a sharpened needle on the positively polarized surface of the pyroelectric crystal results in sufficient field intensification to field ionize background deuterium molecules in a test chamber, and subsequently accelerate the ions to energies in excess of ˜100 keV, sufficient for either D-D or D-T fusion reactions with appropriate target materials. Further increase in ion beam current can be achieved through optimization of crystal thermal ramping, ion source and crystal accelerator configuration. The advantage of such a system is the compact size along with elimination of large, high voltage power supplies. A novel implementation discussed incorporates an independently controlled ion source in order to provide pulsed neutron operation having microsecond pulse width.

  5. A dual neutron/gamma source for the Fissmat Inspection for Nuclear Detection (FIND) system.

    Doyle, Barney Lee (Sandia National Laboratories, Albuquerque, NM); King, Michael; Rossi, Paolo (Sandia National Laboratories, Albuquerque, NM); McDaniel, Floyd Del (Sandia National Laboratories, Albuquerque, NM); Morse, Daniel Henry; Antolak, Arlyn J.; Provencio, Paula Polyak (Sandia National Laboratories, Albuquerque, NM); Raber, Thomas N.

    2008-12-01

    Shielded special nuclear material (SNM) is very difficult to detect and new technologies are needed to clear alarms and verify the presence of SNM. High-energy photons and neutrons can be used to actively interrogate for heavily shielded SNM, such as highly enriched uranium (HEU), since neutrons can penetrate gamma-ray shielding and gamma-rays can penetrate neutron shielding. Both source particles then induce unique detectable signals from fission. In this LDRD, we explored a new type of interrogation source that uses low-energy proton- or deuteron-induced nuclear reactions to generate high fluxes of mono-energetic gammas or neutrons. Accelerator-based experiments, computational studies, and prototype source tests were performed to obtain a better understanding of (1) the flux requirements, (2) fission-induced signals, background, and interferences, and (3) operational performance of the source. The results of this research led to the development and testing of an axial-type gamma tube source and the design/construction of a high power coaxial-type gamma generator based on the {sup 11}B(p,{gamma}){sup 12}C nuclear reaction.

  6. Determination of neutron generation time in miniature neutron source reactor by measurement of neutronics transfer function

    Hainoun, A.; Khamis, I. [Atomic Energy Commission, Damascus (Syria). Dept. of Physics

    2000-02-01

    The prompt neutron generation time {lambda} and the total effective fraction of delayed neutrons (including the effect of photoneutrons) {beta} have been experimentally determined for the miniature neutron source reactor (MNSR) of Syria. The neutron generation time was found by taking measurements of the reactor open-loop transfer function using newly devised reactivity-step-ejection method by the reactor pneumatic rabbit system. Small reactivity perturbations i.e. step changes of reactivity starting from steady state, were introduced into the reactor during operation at low power level i.e. zero-power. Relative neutron flux and reactivity versus time were obtained. Using transfer function analysis as well as least square fitting techniques and measuring the delayed neutrons fraction, the neutron generation time was determined to be 74.6{+-}1.57 {mu}s. Using the prompt jump approximation of neutron flux, the total effective fraction of delayed neutrons was measured and found to be 0.00783{+-}0.00017. Measured values of {lambda} and {beta} were found to be very consistent with calculated ones reported in the safety analysis report. (orig.)

  7. Determination of neutron generation time in miniature neutron source reactor by measurement of neutronics transfer function

    The prompt neutron generation time Λ and the total effective fraction of delayed neutrons (including the effect of photoneutrons) β have been experimentally determined for the miniature neutron source reactor (MNSR) of Syria. The neutron generation time was found by taking measurements of the reactor open-loop transfer function using newly devised reactivity-step-ejection method by the reactor pneumatic rabbit system. Small reactivity perturbations i.e. step changes of reactivity starting from steady state, were introduced into the reactor during operation at low power level i.e. zero-power. Relative neutron flux and reactivity versus time were obtained. Using transfer function analysis as well as least square fitting techniques and measuring the delayed neutrons fraction, the neutron generation time was determined to be 74.6±1.57 μs. Using the prompt jump approximation of neutron flux, the total effective fraction of delayed neutrons was measured and found to be 0.00783±0.00017. Measured values of Λ and β were found to be very consistent with calculated ones reported in the safety analysis report. (orig.)

  8. Measurement of subcriticality using delayed neutron source combined with pulsed neutron accelerator

    A new experimental method for subcriticality measurement was developed by using delayed neutron source which is produced by external pulsed neutron source to increase accuracy of measured results by overcoming the space dependency problem which means difference of measured results in different detector position and often appeared in almost all other subcriticality measurement techniques. Experiments were performed at Kyoto University Critical Assembly (KUCA) combined with a DT accelerator to produce pulsed neutron in outside of the core repeatedly. In this method, neutron detection counts in the prompt neutron time region which are appeared just after injection of pulsed neutron are omitted, whereas neutron counts in the delayed neutron time region which are appeared after disappearance of exponential decay of the prompt neutron are adopted in analysis based on neutron source multiplication method or neutron noise analysis method; the variance to mean ratio method. In the delayed neutron time region, neutron sources to initiate fission chain reactions in subcritical state are delayed neutrons from delayed neutron precursors which are mainly produced by fission chain reactions in the prompt neutron time region, and delayed neutron precursors exist only in the fuel region, which makes possible to decrease the space dependency problem. The obtained results were compared with conventional pulsed neutron method, and it was found that the space dependency problem in subcriticality measurement can be fairly decreased by using the present new method compared with conventional one. (author)

  9. INJECTION CHOICE FOR SPALLATION NEUTRON SOURCE RING

    Injection is key in the low-loss design of high-intensity proton facilities like the Spallation Neutron Source (SNS). During the design of both the accumulator and the rapid-cycling-synchrotron version of the SNS, extensive comparison has been made to select injection scenarios that satisfy SNS's low-loss design criteria. This paper presents issues and considerations pertaining to the final choice of the SNS injection systems

  10. Spallation Neutron Source Radiation Shielding Issues

    This paper summarizes results of Spallation Neutron Source calculations to estimate radiation hazards and shielding requirements for activated Mercury, target components, target cooling water, and 7Be plateout. Dose rates in the accelerator tunnel from activation of magnets and concrete were investigated. The impact of gaps and other streaming paths on the radiation environment inside the test cell during operation and after shutdown were also assessed

  11. Neutron sources and its dosimetric characteristics

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

  12. Linac-driven spallation-neutron source

    Strong interest has arisen in accelerator-driven spallation-neutron sources that surpass existing facilities (such as ISIS at Rutherford or LANSCE at Los Alamos) by more than an order of magnitude in beam power delivered to the spallation target. The approach chosen by Los Alamos (as well as the European Spallation Source) provides the full beam energy by acceleration in a linac as opposed to primary acceleration in a synchrotron or other circular device. Two modes of neutron production are visualized for the source. A short-pulse mode produces 1 MW of beam power (at 60 pps) in pulses, of length less than 1 ms, by compression of the linac macropulse through multi-turn injection in an accumulator ring. A long-pulse mode produces a similar beam power with 1-ms-long pulses directly applied to a target. This latter mode rivals the performance of existing reactor facilities to very low neutron energies. Combination with the short-pulse mode addresses virtually all applications

  13. The spallation neutron source: New opportunities

    Ian S Anderson

    2008-11-01

    The spallation neutron source (SNS) facility became operational in the spring of 2006, and is now well on its way to become the world-leading facility for neutron scattering. Furthermore, the SNS and the HFIR reactor facility, newly outfitted with a brilliant cold source and guide hall, were brought together within a single Neutron Sciences Directorate at ORNL providing the opportunity to develop science and instrumentation programs which take advantage of the unique characteristics of each source. SNS and HFIR will both operate as scientific user facilities. Access to these facilities is being managed under an integrated proposal system, which also includes the Center for Nanophase Materials Sciences (CNMS) and the electron microscopes in the Shared Research Equipment (SHARE) program. Presently, SNS has three instruments operating in the user program and seven more will begin operations in 2008. When complete, the facility will accommodate 25 instruments enabling researchers from the United States and abroad to study materials science that forms the basis for new technologies in telecommunications, manufacturing, transportation, information technology, biotechnology, and health.

  14. Measurements on H- sources for spallation neutron source application

    Lawrence Berkeley National Laboratory is engaged in the development of H- ion sources for the upgrade of the Los Alamos Neutron Science Center (LANSCE) facility and the spallation neutron source (SNS) to be built in the U.S. For the upgrade of the LANSCE facility, the H- ion generator has to deliver an output current of 40 mA. The repetition rate must be 120 Hz at a pulse length of 1 ms (12% duty factor). Furthermore, the normalized emittance must be less than 0.1π mm mrad. During the last years, the Ion Beam Technology Group of the LBNL improved the so-called surface conversion source for the generation of higher H- currents. In the first part of this article, we discuss the operation conditions of the source at the required 40 mA output current. The ion source for the 1 MW spallation neutron source is required to provide 35 mA of H- beam current at 6% duty factor (1 ms pulses at 60 Hz) with a normalized rms emittance of less than 0.2π mm mrad. The H- beam will be accelerated to 65 keV and matched into a 2.5 MeV RFQ. The ion source is expected to ultimately produce 70 mA of H- at 6% duty factor when the SNS is upgraded to 2 MW of power. For this application, a radio-frequency driven, magnetically filtered multicusp source is being developed at LBNL. Experimental results (including emittance measurements) on the performance of the prototype ion source operated at the demanded beam parameters will be presented in this article. (c) 2000 American Institute of Physics

  15. Miniature neutron sources: Thermal neutron sources and their uses in the academic field

    The three levels of thermal neutron sources are introduced: university laboratory sources; infrastructure sources; and world-class sources; and the needs for each kind and their inter-dependence will be emphasized. A description of the possibilities for university sources based on α-Be reactions or spontaneous fission emission is given, and current experience with them is described. A new generation of infrastructure sources is needed to continue the regional programs based on small reactors. Some possibilities for accelerator sources that could meet this need are considered

  16. Applications of the advanced neutron source reactor

    When the technique of neutron scattering was pioneered at the X-10 graphite reactor at Oak Ridge National Laboratory about 50 years ago, it was used to study certain important, but fairly esoteric, properties of crystals. From this modest beginning, neutron scattering has become a major tool in every branch of science, from the astrophysics of the early universe to human biology, and in many important industrial and engineering applications. In a typical modern research reactor it is not unusual to find one instrument studying new polymeric materials, while its neighbor is measuring residual stress in a jet turbine, sometimes with the jet operating. Most of this development has taken place outside of the United States, primarily in Western Europe, Japan and Russia, and it is generally recognized that we are a decade behind our competitors in this important field. The Advanced Neutron Source (ANS), planned to become operational as a user-facility at Oak Ridge at the end of this decade, will regain our leadership in neutron-based research and will be a major center for attracting new students into science. This paper discusses some of the research and development applications of the ANS, with an emphasis on applied materials science and engineering

  17. Advanced Neutron Source: Plant Design Requirements

    1990-07-01

    The Advanced Neutron Source will be a new world-class facility for research using hot, thermal, cold, and ultra-cold neutrons. The heart of the facility will be a 330-MW (fission), heavy-water cooled and heavy-water moderated reactor. The reactor will be housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides will fan out into a large guide hall, housing about 30 neutron research stations. Appropriate office, laboratory, and shop facilities will be included to provide a complete facility for users. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory early in the next decade. This PDR document defines the plant-level requirements for the design, construction, and operation of ANS. It also defines and provides input to the individual System Design Description (SDD) documents. Together, this PDR document and the set of SDD documents will define and control the baseline configuration of ANS.

  18. Cold neutron source with self-regulation

    A way to increase the cold neutron flux is to cool moderator from where cold neutrons are extracted. Although various kinds of cooling system are considered, the closed thermo-siphon cooling system is adopted in many institutes. The notable feature of this system is to be able to keep the liquid level stable in the moderator cell against thermal disturbances, by using self-regulation, which allows a stable supply of cold neutrons. The main part of the closed thermo-siphon consists of a condenser, a moderator transfer tube and moderator cell, which is called the hydrogen cold system. When an extra heat load is applied to the hydrogen cold system having no flow resistance in a moderator transfer tube, the system pressure rises by evaporation of liquid hydrogen. Then the boiling point of hydrogen rises. The liquefaction capacity of the condenser is increasing with a rise of temperature, because a refrigerating power of the helium refrigerator increases linearly with temperature rise of the system. Therefore, the effect of thermal heat load increase is compensated and cancelled out. The closed thermo-siphon has this feature generally, when the moderator transfer tube is designed to be no flow resistance. The report reviews the concept of self-regulation, and how to design and construct the cold neutron source with self-regulation. (author)

  19. Advanced Neutron Sources: Plant Design Requirements

    The Advanced Neutron Source (ANS) is a new, world class facility for research using hot, thermal, cold, and ultra-cold neutrons. At the heart of the facility is a 350-MWth, heavy water cooled and moderated reactor. The reactor is housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides fans out into a large guide hall, housing about 30 neutron research stations. Office, laboratory, and shop facilities are included to provide a complete users facility. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory at the end of the decade. This Plant Design Requirements document defines the plant-level requirements for the design, construction, and operation of the ANS. This document also defines and provides input to the individual System Design Description (SDD) documents. Together, this Plant Design Requirements document and the set of SDD documents will define and control the baseline configuration of the ANS

  20. Advanced Neutron Source: Plant Design Requirements

    The Advanced Neutron Source will be a new world-class facility for research using hot, thermal, cold, and ultra-cold neutrons. The heart of the facility will be a 330-MW (fission), heavy-water cooled and heavy-water moderated reactor. The reactor will be housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides will fan out into a large guide hall, housing about 30 neutron research stations. Appropriate office, laboratory, and shop facilities will be included to provide a complete facility for users. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory early in the next decade. This PDR document defines the plant-level requirements for the design, construction, and operation of ANS. It also defines and provides input to the individual System Design Description (SDD) documents. Together, this PDR document and the set of SDD documents will define and control the baseline configuration of ANS

  1. Target technology of high energy neutron source

    As a facility of high energy neutron source for materials research and development, Fusion Materials Irradiation Test Facility (FMIT) is a strong candidate. The FMIT is designed to study the irradiation effect of fusion neutron on a fusion reactor materials. The FMIT generates a high-flux, high-energy neutron, which is produced in a stripping reaction by impinging a 3.5 MeV-0.1A beam of deuterons on a flowing lithium target. Target technology obtained in the FMIT will be useful for Energy Selective Neutron Irradiation Test Facility (ESNIT) and IFMIF of D-Li stripping reaction facility. In the first report (I), the flowing lithium target of the FMIT was reviewed, and some technical considerations in design were pointed out. In the second report (II), the target assembly and target material were proposed as the option of the HEDEL reference design of FMIT in order to improve the hazard and economy for the Li system: Firstly, the exchangeable target back wall and the measures to minimize the outside device damage in case of back wall breaking, and secondly, the option of molten fluoride salt as target material were proposed. (M.T.)

  2. Advanced Neutron Sources: Plant Design Requirements

    1990-07-01

    The Advanced Neutron Source (ANS) is a new, world class facility for research using hot, thermal, cold, and ultra-cold neutrons. At the heart of the facility is a 350-MW{sub th}, heavy water cooled and moderated reactor. The reactor is housed in a central reactor building, with supporting equipment located in an adjoining reactor support building. An array of cold neutron guides fans out into a large guide hall, housing about 30 neutron research stations. Office, laboratory, and shop facilities are included to provide a complete users facility. The ANS is scheduled to begin operation at the Oak Ridge National Laboratory at the end of the decade. This Plant Design Requirements document defines the plant-level requirements for the design, construction, and operation of the ANS. This document also defines and provides input to the individual System Design Description (SDD) documents. Together, this Plant Design Requirements document and the set of SDD documents will define and control the baseline configuration of the ANS.

  3. The Chinese Spallation Neutron Source Project

    The proposal of the Chinese Spallation Neutron Source (CSNS) project was granted in the beginning of 2002 after three review meetings, organized by the Chinese Academy of Sciences (CAS) and other scientific organizations. Physicists from the Institute of Physics (IP) and the Institute of High Energy Physics (IHEP), both belonging to CAS, consequently started a conceptual design and feasibility study. The CSNS plan calls for a 70-MeV H- linac and a 1.6 GeV rapid cycling synchrotron producing a proton current of 62.5 μA (100kW) at a 25 Hz repetition rate. It should be able to be upgraded to a higher beam power in its second phase. The CSNS target station design team, has initiated to conceptual design of the targetmoderator system based on the suggestions and comments from an international advisory team, in the first moderator-target planning meeting of CSNS project (21-26, April 2002 in Beijing). In consideration of the characteristics of the spallation neutron source, the budgets and possible requests for future users in China, five multi-purpose neutron scattering spectrometers were proposed as the first step

  4. Neutron source based on the TORNADO trap

    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

  5. Advanced neutron source materials surveillance program

    The Advanced Neutron Source (ANS) will be composed of several different materials, one of which is 6061-T6 aluminum. Among other components, the reflector vessel and the core pressure boundary tube (CPBT), are to be made of 6061-T6 aluminum. These components will be subjected to high thermal neutron fluences and will require a surveillance program to monitor the strength and fracture toughness of the 6061-T6 aluminum over their lifetimes. The purpose of this paper is to explain the steps that were taken in the summer of 1994 toward developing the surveillance program. The first goal was to decide upon standard specimens to use in the fracture toughness and tensile testing. Second, facilities had to be chosen for specimens representing the CPBT and the reflector vessel base, weld, and heat-affected-zone (HAZ) metals. Third, a timetable had to be defined to determine when to remove the specimens for testing

  6. Development of Systems for Cold Neutron Source

    The design technology of CNS(Cold Neutron Source) facility system is a high technology which only a few advanced countries possess and is considered as a core technology in this particular situation that we are trying to move into higher level among nuclear energy countries. Especially, the very low temperature control and the vacuum control technology will be the basic important technique in high-tech field and furthermore, this will raise up the national power with the core neutron dispersion research center in the Northeast Asia. This original design technique will contribute to generate new other original technology through the fusion with RT, NT and BT, and improve the export competitiveness of the research reactor

  7. Inertial electro-magnetostatic plasma neutron sources

    Two types of systems are being studied experimentally as D-T plasma neutron sources. In both concepts, spherical convergence of either electrons or ions or both is used to produce a dense central focus within which D-T fusion reactions produce 14 MeV neutrons. One concept uses nonneutral plasma confinement principles in a Penning type trap. In this approach, combined electrostatic and magnetic fields provide a vacuum potential well within which electrons are confined and focused. A small (6 mm radius) spherical machine has demonstrated a focus of 30 microm radius, with a central density of up to 35 times the Brillouin density limit of a static trap. The resulting electron plasma of up to several 1013 cm-3 provides a multi-kV electrostatic well for confining thermonuclear ions as a neutron source. The second concept (Inertial Electrostatic Confinement, or IEC) uses a high-transparence grid to form a global well for acceleration and confinement of ions. Such a system has demonstrated steady neutron output of 2 x 1010 s-1. The present experiment will scale this to >1011 s-1. Advanced designs based on each concept have been developed recently. In these proposed approaches, a uniform-density electron sphere forms an electrostatic well for ions. Ions so trapped may be focused by spherical convergence to produce a dense core. An alternative approach produces large amplitude spherical oscillations of a confined ion cloud by a small, resonant modulation of the background electrons. In both the advanced Penning trap approach and the advanced IEC approach, the electrons are magnetically insulated from a large (up to 100 kV) applied electrostatic field. The physics of these devices is discussed, experimental design details are given, present observations are analyzed theoretically, and the performance of future advanced systems are predicted

  8. Shielding the LANSCE [Los Alamos Neutron Scattering Center] 800-MeV spallation neutron source

    Neutrons produced by medium-energy (800-MeV) proton reactions at the Los Alamos Neutron Scattering Center spallation neutron source cause a variety of difficult shield problems. We describe the general shielding questions encountered at such a spallation source, and contrast spallation and reactor source shielding issues using an infinite slab-shield composed of 100 cm of iron and 15 cm of borated polyethylene. The calculations show that (for an incident spallation spectrum characteristic of neutrons leaking at 90 degrees from a tungsten target) high-energy neutrons dominate the dose at the shield surface. Secondary low-energy neutrons (produced by high-energy neutron attenuation) and attendant gamma-rays add significantly to the dose. The primary low-energy neutrons produced directly at the tungsten source contribute negligibly to the dose, and behave similarly to neutrons with a fission spectrum distribution. 8 refs., 10 figs

  9. Neutron diffractometers for structural biology at spallation neutron sources

    Schoenborn, B.P.; Pitcher, E. [Los Alamos National Laboratory, NM (United States)

    1994-12-31

    Spallation neutron sources are ideal for diffraction studies of proteins and oriented molecular complexes. With spoliation neutrons and their time dependent wavelength structure, it is easy to electronically select data with an optimal wavelength bandwidth and cover the whole Laue spectrum as time (wavelength) resolved snapshots. This optimized data quality with best peak-to-background ratios and provides adequate spatial and energy resolution to eliminate peak overlaps. The application of this concept will use choppers to select the desired Laue wavelength spectrum and employ focusing optics and large cylindrical {sup 3}He detectors to optimize data collection rates. Such a diffractometer will cover a Laue wavelength range from 1 to 5{Angstrom} with a flight path length of 10m and an energy resolution of 0.25{Angstrom}. Moderator concepts for maximal flux distribution within this energy range will be discussed using calculated flux profiles. Since the energy resolution required for such timed data collection in this super Laue techniques is not very high, the use of a linac only (LAMPF) spoliation target is an exciting possibility with an order of magnitude increase in flux.

  10. Neutron diffractometers for structural biology at spallation neutron sources

    Spallation neutron sources are ideal for diffraction studies of proteins and oriented molecular complexes. With spoliation neutrons and their time dependent wavelength structure, it is easy to electronically select data with an optimal wavelength bandwidth and cover the whole Laue spectrum as time (wavelength) resolved snapshots. This optimized data quality with best peak-to-background ratios and provides adequate spatial and energy resolution to eliminate peak overlaps. The application of this concept will use choppers to select the desired Laue wavelength spectrum and employ focusing optics and large cylindrical 3He detectors to optimize data collection rates. Such a diffractometer will cover a Laue wavelength range from 1 to 5 Angstrom with a flight path length of 10m and an energy resolution of 0.25 Angstrom. Moderator concepts for maximal flux distribution within this energy range will be discussed using calculated flux profiles. Since the energy resolution required for such timed data collection in this super Laue techniques is not very high, the use of a linac only (LAMPF) spoliation target is an exciting possibility with an order of magnitude increase in flux

  11. Neutrons for technology and science

    Aeppli, G.

    1995-10-01

    We reviewed recent work using neutrons generated at nuclear reactors an accelerator-based spallation sources. Provided that large new sources become available, neutron beams will continue to have as great an impact on technology and science as in the past.

  12. A status report on the advanced neutron source project

    Design work on the Advanced Neutron Source facilities has progressed significantly, with cost saving changes to the buildings and other systems. The cold source design has advanced considerably, and in addition design work has been initiated on the hot neutron source and on a positron source. (J.P.N.)

  13. Benchmarking shielding simulations for an accelerator-driven spallation neutron source

    Cherkashyna, Nataliia; DiJulio, Douglas D.; Panzner, Tobias; Rantsiou, Emmanouela; Filges, Uwe; Ehlers, Georg; Bentley, Phillip M.

    2015-08-01

    The shielding at an accelerator-driven spallation neutron facility plays a critical role in the performance of the neutron scattering instruments, the overall safety, and the total cost of the facility. Accurate simulation of shielding components is thus key for the design of upcoming facilities, such as the European Spallation Source (ESS), currently in construction in Lund, Sweden. In this paper, we present a comparative study between the measured and the simulated neutron background at the Swiss Spallation Neutron Source (SINQ), at the Paul Scherrer Institute (PSI), Villigen, Switzerland. The measurements were carried out at several positions along the SINQ monolith wall with the neutron dosimeter WENDI-2, which has a well-characterized response up to 5 GeV. The simulations were performed using the Monte-Carlo radiation transport code geant4, and include a complete transport from the proton beam to the measurement locations in a single calculation. An agreement between measurements and simulations is about a factor of 2 for the points where the measured radiation dose is above the background level, which is a satisfactory result for such simulations spanning many energy regimes, different physics processes and transport through several meters of shielding materials. The neutrons contributing to the radiation field emanating from the monolith were confirmed to originate from neutrons with energies above 1 MeV in the target region. The current work validates geant4 as being well suited for deep-shielding calculations at accelerator-based spallation sources. We also extrapolate what the simulated flux levels might imply for short (several tens of meters) instruments at ESS.

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

    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)

  15. Physics and technology of spallation neutron sources

    Next to fission and fusion, spallation is an efficient process for releasing neutrons from nuclei. Unlike the other two reactions, it is an endothermal process and can, therefore, not be used per se in energy generation. In order to sustain a spallation reaction, an energetic beam of particles, most commonly protons, must be supplied onto a heavy target. Spallation can, however, play an important role as a source of neutrons whose flux can be easily controlled via the driving beam. Up to a few GeV of energy, the neutron production is roughly proportional to the beam power. Although sophisticated Monte Carlo codes exist to compute all aspects of a spallation facility, many features can be understood on the basis of simple physics arguments. Technically a spallation facility is very demanding, not only because a reliable and economic accelerator of high power is needed to drive the reaction, but also, and in particular, because high levels of radiation and heat are generated in the target which are difficult to cope with. Radiation effects in a spallation environment are different from those commonly encountered in a reactor and are probably even more temperature dependent than the latter because of the high gas production rate. A commonly favored solution is the use of molten heavy metal targets. While radiation damage is not a problem in this case, except for the container, a number of other issues are discussed. (author)

  16. UCN Source at an External Beam of Thermal Neutrons

    2015-01-01

    We propose a new method for production of ultracold neutrons (UCNs) in superfluid helium. The principal idea consists in installing a helium UCN source into an external beam of thermal or cold neutrons and in surrounding this source with a solid methane moderator/reflector cooled down to ~4 K. The moderator plays the role of an external source of cold neutrons needed to produce UCNs. The flux of accumulated neutrons could exceed the flux of incident neutrons due to their numerous reflections ...

  17. Development and Production Of An 805-MHz, 550 kW Pulsed Klystron For The Spallation Neutron Source

    The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built in Oak Ridge, Tennessee, by the U.S. Department of Energy. The SNS will provide the most intense pulsed neutron beams in the world for scientific research and industrial development. CPI is supporting the effort by providing 550 kW pulsed klystrons for the superconducting portion of the accelerator. A total of 73 units are on order. The primary output power requirements are 550 kW peak, 49.5 kW average at 805 MHz, with an electron beam-to-rf conversion efficiency of 65% and an rf gain of 50 dB. To date, 25 units have been factory tested. Performance specifications, computer-model predictions, and operating results are presented

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

    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. Analysis of beam-on-target interaction in a neutron-source test facility

    The need is urgent for a high-flux, high-energy neutron test facility to evaluate the performance of fusion reactor materials. An accelerator-based deuterium-lithium source is generally considered the most reasonable approach to a high-flux neutron source in the near future. The idea is to bombard a high-energy (20--40 MeV) deuteron beam into a lithium jet target to produce high-energy neutrons in order to simulate a fusion reactor environment via the Li (d, n) nuclear stripping reaction. Deposition of the high-energy deuteron beam and the subsequent response of the lithium jet are modeled and evaluated in detail. To assess the feasibility of this concept, the analysis is done parametrically for various deuteron beam energies, beam currents, and jet velocities. A main requirement for a successful operation is to keep the free jet surface at a minimum temperature to reduce surface evaporation of lithium into the vacuum system. The effects of neutron-generated heating and irradiation on the jet-supporting back plate are also evaluated. The back plate must maintain a reasonable lifetime during system operation

  20. Analysis of beam on target interaction in a neutron-source test facility

    The need is urgent for a high-flux, high-energy neutron test facility to evaluate the performance of fusion reactor materials. An accelerator-based deuterium-lithium source is generally considered the most reasonable approach to a high-flux neutron source in the near future. The idea is to bombard a high-energy (20--40 MeV) deuteron beam into a lithium jet target to produce high-energy neutrons in order to simulate a fusion reactor environment via the Li (d,n) nuclear stripping reaction. Deposition of the high-energy deuteron beam and the subsequent response of the lithium jet are modeled and evaluated in detail. To assess the feasibility of this concept, the analysis is done parametrically for various deuteron beam energies, beam currents, and jet velocities. A main requirement for a successful operation is to keep the free jet surface at a minimum temperature to reduce surface evaporation of lithium into the vacuum system. The effects of neutron-generated heating and irradiation on the jet-supporting back plate are also evaluated. The back plate must maintain a reasonable lifetime during system operation

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

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

  2. The Jülich high-brilliance neutron source project

    Rücker, U.; Cronert, T.; Voigt, J.; Dabruck, J. P.; Doege, P.-E.; Ulrich, J.; Nabbi, R.; Beßler, Y.; Butzek, M.; Büscher, M.; Lange, C.; Klaus, M.; Gutberlet, T.; Brückel, T.

    2016-01-01

    With the construction of the European Spallation Source ESS, the European neutron user community is looking forward to the brightest source worldwide. At the same time there is an ongoing concentration of research with neutrons to only a few but very powerful neutron facilities. Responding to this situation the Jülich Centre for Neutron Science has initiated a project for a compact accelerator driven high-brilliance neutron source, optimized for neutron scattering on small samples and to be realized at reasonable costs. The project deals with the optimization of potential projectiles, target and moderator concepts, versatile accelerator systems, cold sources, beam extraction systems and optimized instrumentation. A brief outline of the project, the achievements already reached, will be presented, as well as a vision for the future neutron landscape in Europe.

  3. Advanced spallation neutron sources for condensed matter research

    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)

  4. Fission, spallation or fusion-based neutron sources

    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.

  5. PGNAA neutron source moderation setup optimization

    Zhang, Jinzhao; Tuo, Xianguo

    2013-01-01

    Monte Carlo simulations were carried out to design a prompt {\\gamma}-ray neutron activation analysis (PGNAA) thermal neutron output setup using MCNP5 computer code. In these simulations the moderator materials, reflective materials and structure of the PGNAA 252Cf neutrons of thermal neutron output setup were optimized. Results of the calcuations revealed that the thin layer paraffin and the thick layer of heavy water moderated effect is best for 252Cf neutrons spectrum. The new design compar...

  6. Time collimation for elastic neutron scattering at a pulsed source

    Conditions for carrying out elastic neutron scattering experiments using the time-of-flight technique are considered. It is shown, that the employment of time dependent neutron beam collimation in the source-sample flight path increases the luminosity of the spectrometer under certain resolution restrictions. Time collimation modes are proposed for small-angle scattering and neutron reflection. (author) 8 figs., 3 refs

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

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

  8. Novel neutron focusing mirrors for compact neutron sources

    Gubarev, M. V.; Zavlin, V. E.; Katz, R.; Resta, G.; Robertson, L; Crow, L.; Ramsey, B. D.; Khaykovich, Boris; Liu, DaZhi; Moncton, David E.

    2012-01-01

    We demonstrated neutron beam focusing and neutron imaging using axisymmetric optics, based on pairs of confocal ellipsoid and hyperboloid mirrors. Such systems, known as Wolter mirrors, are commonly used in x-ray telescopes. A system containing four nested Ni mirror pairs was implemented and tested by focusing a polychromatic neutron beam at the MIT Reactor and conducting an imaging experiment at HFIR. The major advantage of the Wolter mirrors is the possibility of nesting for large angular c...

  9. Reactor - and accelerator-based filtered beams

    The neutrons produced in high flux nuclear reactors and in accelerator, induced fission and spallation reactions, represent the most intense sources of neutrons available for research. However, the neutrons from these sources are not monoenergetic, covering the broad range extending from 10-3 eV up to 107 eV or so. In order to make quantitative measurements of the effects of neutrons and their dependence on neutron energy it is desirable to have mono-energetic neutron sources. The paper describes briefly methods of obtaining mono-energetic neutrons and different methods of filtration. This is followed by more detailed discussion of neutron window filters and a summary of the filtered beam facilities using this technique. The review concludes with a discussion of the main applications of filtered beams and their present and future importance

  10. Low dimensional neutron moderators for enhanced source brightness

    Mezei, Ferenc; Zanini, Luca; Takibayev, Alan;

    2014-01-01

    In a recent numerical optimization study we have found that liquid para-hydrogen coupled cold neutron moderators deliver 3–5 times higher cold neutron brightness at a spallation neutron source if they take the form of a flat, quasi 2-dimensional disc, in contrast to the conventional more voluminous...... cold neutrons. This model leads to the conclusions that the optimal shape for high brightness para-hydrogen neutron moderators is the quasi 1-dimensional tube and these low dimensional moderators can also deliver much enhanced cold neutron brightness in fission reactor neutron sources, compared to the...... shapes used by now. In the present paper we describe a simple theoretical explanation of this unexpected behavior, which is based on the large difference in para-hydrogen between the values of the scattering mean free path for thermal neutrons (in the range of 1 cm) and its much larger equivalent for...