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A hybrid position-sensitive neutron detector with active 10B-layer and proportional chamber filled by the gas mixture Ar+25%CO2 is being studied. The detector is used on the neutron source based at the linear accelerator. Recording two pairs of pulse heights which are produced in two gas gaps by 7Li and 4He nuclei between the anode and two cathodes gives a possibility to determine the X and Y neutron coordinates. This detector permits time-of-flight measurements. A significant difference in pulse height spectra for slow and fast (several MeV) neutrons was observed in experiment. In recent experiments with 10B-detector we found that (1) the pulse heights depend on the neutron energy and (2) the position of the maximum in the pulse height spectrum varies monotonically versus the maximum neutron energy. [ABSTRACT FROM AUTHOR]

We aim at building a compact accelerator-based neutron source (CANS) which would provide a thermal neutron flux on the order of 4x1012 n.s-1.cm-2.sr-1. Such a brilliance would put compact neutron sources on par with existing medium flux neutron research reactors for neutron scattering experiments. We performed the first neutron production tests on the IPHI proton accelerator at Saclay at a proton energy of 3 MeV. The thermal neutron flux were measured using gold foil activation and 3He detectors. The measured flux were compared with GEANT4 Monte Carlo simulations (10.4) in which the whole experimental setup was modelled. There is a good agreement between the experimental measurements and the Monte-Carlo simulations. The available modelling tools will allow us to optimize the whole Target Moderator Reflector assembly together with the neutron scattering spectrometer geometries for the design of the neutron scattering facility SONATE. [ABSTRACT FROM AUTHOR]

Concrete structure has been widely used in bridges and highways, however, its performance will be deteriorated after long term serving or suffering disaster. Since fast neutron has strong transmission ability and is sensitive to water content in the concrete structure, it can provide an effective probe to inspect the inner structure of concrete with non-destructive way. Thus, we propose a fast neutron imaging and reconstruction system of 3D CT for concrete structure inspection with Riken accelerator-driven compact neutron source (RANS) using a fast neutron pixel-type detector, which has 8×8 pixels. To have a good space resolution on the reconstructed image, a rotation + linear scanning method is devised and is used to collect the projection data from experiment or calculation. In this paper, reconstruction for a concrete object containing both iron bars and acrylic bars for simulation of water has been conducted. As a result, 3D image of 1cm diameter bar is reconstructed by the sparse reconstruction algorithm. [ABSTRACT FROM AUTHOR]

In thermal nuclear reactors, most of the power is generated by thermal neutron induced fission. Therefore, fission chambers with targets that respond directly to slow neutrons are of great interest for thermal neutron flux measurements due to relatively low sensitivity to gamma radiation. However, the extreme conditions associated with experiments at very low cross section demand highly possible thermal neutron flux, leading often to substantial design changes. In this paper we report design of a fission chamber for wide range (from 10 to 1012 n/cm2 sec) measurement of thermal neutron flux. Test experiments were performed at the first beam of IBR2 pulsed reactor using digital pulse processing (DPP) technique with modern waveform digitizers (WFD). The neutron pulses detected by the fission chamber in each burst (5 Hz repetition rate) of the reactor were digitized and recorded to PC memory for further on-line and off-line analysis. New method is suggested to make link between the pulse counting, the current mode and the Campbell technique. [ABSTRACT FROM AUTHOR]

To meet strong demand for realizing an effective tool to diagnose salt distribution in concrete infrastructures, we have started a development of a new technique using a prompt gamma neutron activation analysis (PGNAA) at the RIKEN accelerator-driven compact neutron source (RANS). So far, by applying PGNAA we have experimentally confirmed that neutrons from RANS can detect small enough amounts of chlorine within the marginal concentration of around 1.2 kg/m3 to involve steel corrosion. In this study, we have proposed two methods to derive the salt depth profile which is critical information of steel corrosion start. The first one utilizes a difference in the intensity ratio of two different γ-ray energies of interest, which is depending on the depth where the neutron capture reaction arises inside the concrete. The second is called the collimator method that measure γ-rays coming through a collimator around detector. Detection of γ-ray associated with 35Cl coming from the assembly of concrete has been also simulated with conditions of neutrons from RANS and a collimator. The feasibility of the method was discussed. [ABSTRACT FROM AUTHOR]

Highly reliable 3He gas detectors are most often used in neutron scattering experiments but have disadvantages such as low count rates and low position resolutions. In this study, a 3He gas detector system called NEUNET-HCR was developed, whose count rate is approximately 10 times that of the current NEUNET system, which was developed for a high position resolution with a low count rate. NEUNET-HCR achieved a maximum count rate of 535 kcps per detector, with a loss of approximately 30%. As the NEUNET-HCR system was developed based on the NEUNET system, various improvements were required to achieve the high count rate. Further, a high count rate was achieved in the NEUNET-HCR system without significantly degrading the position resolution. [ABSTRACT FROM AUTHOR]

In the frame of direct dark matter search, the fast neutrons producing elastic collisions on the nuclei of the active volume are the ultimate background. The MIMAC (MIcro-tpc MAtrix Chambers) project has developed a directional detector providing the directional signature to discriminate them from the searched events based on 3D nuclear tracks reconstruction. The MIMAC team of the LPSC has adapted one MIMAC chamber as a mobile fast neutron spectrometer, the Mimac-FastN detector, having a wide neutron energy range (10 keV – 600 MeV) working with different gas mixtures and pressures. This presentation will be focused on the MeV range with 4He + 5% CO2 gas mixture at 700 mbar. A boron coating inside the active volume used for calibration purpose opens the possibility to use the active volume as an active phantom for Boron Neutron Capture Therapy (BNCT) and Proton Fusion Boron Therapy (PFBT). [ABSTRACT FROM AUTHOR]

The Nagoya University Accelerator driven Neutron Source (NUANS) is constructed at the main campus of the Nagoya University. The electrostatic accelerator is used with the maximum proton energy and intensity of 2.8MeV, 15mA(42kW) respectively. Two neutron beamlines are designed at NUANS. The BL1 is dedicated to BNCT development. The BL2 is designed for research and development for neutron devices and neutron imaging. The neutrons used for the BL2 are generated by using the (p, n) reaction from a thin beryllium target. We constructed a compact target station for the BL2 and measured the neutron transmission image. [ABSTRACT FROM AUTHOR]

Neutron imaging offers unique capabilities not limited to the structural characterisation of materials, components and processes at a large variety of neutron sources and thus is highly qualified to be a prime candidate for instrumentation at compact neutron sources. The peculiar characteristics of neutrons, and in particular the cross sections for their interaction with matter enable imaging results that are directly comparable but, most notably, are effectively complementary to those of wide spread X-ray imaging characterisation. Here, it is highlighted how neutron imaging can significantly add to the value and the versatility of basically all and especially future compact neutron sources. Diverse advantages are identified at all possible sizes and levels of sophistication of compact sources. These areas range from source characterisation and students training to state of the art neutron imaging in 3D to applications and method development, which are possible at compact sources and some of which can take particular advantage of advanced source characteristics such as e.g. several target stations at a single accelerator. [ABSTRACT FROM AUTHOR]

Small-angle neutron scattering (SANS) is an important tool to investigate material properties in nanometer to micrometer scale. The opportunity to conduct SANS experiments is, however, limited because of the low number of available SANS beam lines. Compact neutron sources are expected to play a significant role to increase neutron scattering facilities including SANS beam lines. The problem is that the flux of compact neutron sources can be very low, which makes it difficult to measure scattered neutrons from a sample. A SANS geometry with ring-shaped collimated beam (r-SANS) is developed to conduct SANS experiments at very low flux neutron sources. By using ring-shaped collimated neutrons to hit a large sample, the scattered neutron flux becomes high on the ring center line because the scattered neutrons with each scattered angle overlaps on each point of the ring center line. By setting a 3He point detector on the center line and shielding the surrounding of the small detection area well, high signal to noise ratio experiments are possible. In this paper, we show the concept of this new geometry and a preliminary experimental result of a glassy carbon sample taken with the r-SANS geometry constructed at Kyoto University proton Accelerator Neutron Source (KUANS). [ABSTRACT FROM AUTHOR]

Cold neutrons with energy less than several meV are good probes for material research, and they have been available on large neutron facilities, whereas it is not commonly available on compact accelerator-driven neutron source. RIKEN Accelerator-driven Neutron Source (RANS) is a pulsed neutron facility which provides thermal neutrons and high energy neutrons at several MeV. We started a project to implement a cold neutron moderator for RANS to broaden cold neutrons applications. A cold neutron moderator system with a mesitylene moderator at 20K and a polyethylene pre-moderator at room temperature in the slab geometry was designed for RANS. So far, the thickness of the pre-moderator and mesitylene have been optimized to get the highest cold neutron flux by using a Monte Carlo simulation code, PHITS. Graphite reflector dimensions were also proven to have significant effect to increase the cold neutron intensity. [ABSTRACT FROM AUTHOR]

A significant contribution to the enhancement of the neutron brilliance achievable with Compact Accelerator-driven Neutron Sources (CANS) can be made by an optimized cold moderator design. When using liquid para-H2 as the moderating medium, the concept of low-dimensional cold moderators can be employed to increase the neutron brightness (as currently foreseen at the European Spallation Source ESS). Para-H2 shows a drop in the scattering cross section by about one order of magnitude around 15 meV, resulting in a large deviation between the mean free paths of thermal and cold neutrons. Taking advantage of this effect, the cold moderator geometry can be optimized to allow the intake of thermal neutrons through a relatively large envelope surface and then extracting them in an efficient way towards the neutron guides. One drawback of this solution is the lack of thermalization of the cold neutrons. In the context of the HBS (High Brilliance Neutron Source) project, efforts are made to overcome this problem by increasing the scattering cross section of the H2 in a defined way. The idea is to admix small amounts of ortho-H2, which maintains its large scattering cross section in the region below 15 meV. Like this, the neutron spectrum can be shifted towards lower energies and adjusted for the needs of the respective instruments. In a cooperation between TU Dresden and FZ Jülich, an experimental setup has been created to prove the feasibility of this concept. The main component of the experimental setup is a LHe-cooled flow cryostat that enables the separate condensation of a para-H2 and a normal-H2 flow and a subsequent mixing of the two in precise proportions. The resulting LH2 mixture at 17 - 20 K is fed into a small cold moderator vessel (approx. 200 ml). In this work, the current status of the setup is presented. The construction and commissioning of the mixing cryostat have been completed and first test runs show that different ortho-para-H2 mixtures can be produced. In the near future, the system will be ready for measurements at a neutron source. [ABSTRACT FROM AUTHOR]

Nanodiamond Particles (NDP) are new candidates for neutron reflection. They have a large scattering and low absorption cross-sections for low-energy neutrons. Very Cold Neutrons (VCN) are reflected from NDP with large scattering angles while Cold Neutrons (CN) have a quasi-specular reflection at small incident angles. A new scattering process has been added in Geant4 in order to examine the directional reflection of CN in an extraction beam made of NDP layer. Impurities in NDP are responsible for the up-scattered neutrons, especially hydrogen which has a large cross-section. Other impurities are also considered in Geant4 in order to produce a more accurate model for NDP scattering. The new scattering process is used to model a possible configuration of target-moderator-reflector in Compact Neutron Sources (CNS). A 13 MeV proton beam striking a beryllium target is chosen. Parahydrogen is placed as a cold moderator in order to produce CN. NDP are placed around the extraction beam for scattering the CN toward the exit of the beam. The results show that CN exiting the extraction beam can be increased thanks to the implemented NDP layer. [ABSTRACT FROM AUTHOR]

Low-dimensional moderators were designed for the European Spallation Source (ESS), and the same concepts can be applied to compact sources. At ESS, quasi two-dimensional (2D) high-brightness moderators will serve all the instruments of the initial suite. The design of the moderators is influenced by several factors, such as the layout of the facility, the requirements for beam extraction, and the number of instruments; these constraints led to the choice of the 2D "butterfly" moderator for ESS. In an accelerator-based compact source, such moderators can be designed in an even more efficient way than for high-power sources, taking advantage of the lower heat loads and of the more compact arrangement of the target-moderator system, which gives more freedom in the optimization of the geometrical setup. Some promising design options have been explored. [ABSTRACT FROM AUTHOR]

Neutron scattering techniques and neutron applications in general are powerful and well-established tools for research in science and technology. However, those are highly intensity-limited techniques and the need to reduce the neutron loses between their source to detection is then an imperative endeavor. In particular, great effort has been devoted to the development of efficient ways to transport and guide neutron beams, as well as to reduce the flux leakage in the non-emitting sides of moderator systems. In this work we investigate and confirm by calculation in a real material the great quality of diamond nanoparticles as reflector for ultra-cold and very-cold neutrons, and propose the use of Magnesium Hydride at a low temperature as a very good reflector for cold neutrons [ABSTRACT FROM AUTHOR]

The neutron yield for compact accelerator driven neutron sources depends on the target material, the ion type and its energy. When such sources are operated with low energy proton beams below 30 MeV, typical target materials are lithium and beryllium. New developments indicate that higher energies or a deuteron beam might be useful to increase the neutron yield at constant accelerator power. Here we present the total neutron yield analytically calculated for protons and deuterons at energies up to 100 MeV for various target materials. The total neutron yield depends on the involved cross sections and the stopping power of the target material. This study shows that for energies lower than 30 MeV light target materials with a deuteron beam are preferable whereas for energies above 30 MeV heavy target materials show a high neutron yield with little difference for a proton or deuteron beam. [ABSTRACT FROM AUTHOR]

With the phasing out of many research reactors over the upcoming years, a shortcoming of small and medium sized neutron sources is to be expected. Laser-driven neutron sources have the potential to fill this void, with enormous progress being made in laser technology over the past years. Upcoming petawatt lasers with high repetition rates up to 10 Hz promise a tremendous increase in neutron flux. In this paper, a setup is developed and optimized to conduct neutron resonance spectroscopy at a laser-driven neutron source. This setup is then evaluated at an experimental campaign at the PHELIX laser system. Laser intensities up to 1021 W/cm² with a ns pre-pulse contrast of 10-7 were used for ion acceleration, resulting in (1.8±0.7)×108 N/sr per pulse corresponding to (2.3±1.0)×109 N in a 4 π equivalent. These pulses were moderated, collimated and investigated via the time of flight method in order to characterize the thermal neutron spectrum as well as the signal to noise ratio. [ABSTRACT FROM AUTHOR]

A compact Liquid Lithium Target (LiLiT) has been operating at SARAF for several years with beam power of several kW (1.9-2.5 MeV, up to 2 mA). When bombarding the lithium with low energy protons neutrons are generated. The neutron source, mainly used for nuclear astrophysics research, was decommissioned in 2016 towards an upgraded model - with possible applications to Boron Neutron Capture Therapy (BNCT) and material-science studies. The improved version has been designed to sustain 50 kW proton beam power (2.5 MeV, ~20 mA) to provide sufficient neutron flux required for clinical BNCT application. The new model has a 50 mm wide lithium jet to enable dissipation of the higher beam power and an improved heat exchanger to remove the power to a secondary cooling loop. A new Annular Linear INduction electro-magnetic pump (ALIN) has been designed and built to provide the required lithium flow rate. Other mechanical improvements facilitate the maintenance of the system and the robustness of operation. Radiological risks due to the 7Be produced in the reaction are reduced by using an integrated lead shielding of the lithium reservoir. An integrated neutron moderator is being designed to adjust the neutron energy to the spectrum best suited to BNCT. A low power (6 kW) model of the new design with a narrower nozzle (18 mm wide) and a rotating-magnet electro-magnetic pump is operating at SARAF to support the ongoing astrophysics and nuclear research program [1], [2]. To fulfill clinical BNCT, the upgraded LiLiT model will require an accelerator of appropriate energy and intensity. The design features of the new system are presented in this paper. [ABSTRACT FROM AUTHOR]

In this contribution, we present the CoolGAL fast neutron production target system, to be used in the initial phase of the NEPIR irradiation beamline at the SPES facility, that will be operational in 2022. Initially, NEPIR will be used for shielding studies against fast neutrons for space applications and to investigate neutron-induced single event effects in microelectronic devices and systems. In CoolGAL, the neutron production component, a thick Be cylinder, is immersed in a static bath of Galinstan, a liquid alloy of Ga, In and Sn, contained by an outer water cooled copper cladding. MCNPX calculations indicate that, by using a 1 μA current of 70 MeV protons, it can produce a fast neutron energy spectrum that is somewhat flat the 30-65 MeV energy range and with a sharp cut-off at the beam energy. At the standard test point, located 2.6 m downstream from the source, the beam spot diameter, defined by the peculiar collimation scheme of the initial phase of NEPIR, is 10 cm and the integral fast neutron flux is Φn(1< En<65 MeV) ~ 3×106 n cm-2s-1. Using proton beams with two different energies, one can calculate, by subtraction, the effects due to the neutrons in the energy interval defined by the two cut-off values. Preliminary results of ANSYS calculations, for a 1 μA proton current of 70 MeV protons (70 W), show a limited regime temperature (28 °C) of the Be component, capable of ensuring the exceptional safety level required for the operation at SPES. The thermal reliability of CoolGAL is very promising for future developments that require higher proton currents. [ABSTRACT FROM AUTHOR]

The High-Brilliance neutron Source project (HBS) aims at developing a medium-flux acceleratordriven neutron source based on a 70 MeV, 100mA proton accelerator. The concept intends to optimize the facility such that it provides high-brilliance neutron beams for instruments operating at di_erent time structures. This can be realized by three di_erent target stations irradiated with di_erent proton pulse sequences. The appropriate proton pulses will be distributed by a Multiplexer unit. In the following, we present the integration of this Multiplexer with the HBS beam optics as well as ongoing developments of this unit and several components of the Multiplexer at the COSY facility in Jülich. [ABSTRACT FROM AUTHOR]

The development of the high intensity compact neutron source is mainly conducted by using accelerators for medical purposes. Recently, a lot of compact neutron sources have been developed, and most of them are for boron neutron capture therapy (BNCT). Compared with the common accelerators used for industries, accelerators for BNCT have to accelerate a 100 times larger current of charged particles because of the low conversion efficiency of neutron moderators. To attain a reliable target for the BNCT neutron source, two obstacles have to be overcome; radiation damage (blistering) and heat issue. We introduce diffusion bonding method aiming to make defect free Be neutron target and 1 MPa latent heat water-cooling system. We also install beam expansion optics using quadrupole and octupole magnets to reduce the charge density. Our facility has been operating for more than three years from the commissioning period and we report the recent situation as following. 1) Diffusion bonding method was applied to the solid neutron target of Be with latent heat cooling system. 2) Amount of integrated coulomb value of protons implanted to the Be target is nearly 3000 C now 3) Amount of neutron dose rate was measured. 4) A laser reflection microscope (LRM) method has been developed to observe the neutron target condition (especially radiation damage) through viewport with a few meters working distance. 5) Direct observation of the surface of the Be target was done during the period of improving nearly target vacuum and residual radiation conditions. From these evidences, we conclude our neutron target already produces neutrons capable to treat nearly 500 patients of malignant melanoma. [ABSTRACT FROM AUTHOR]

The Radio Frequency Quadrupole (RFQ) linear accelerator for ESS-Bilbao is described. This device will complete ESS-Bilbao injection chain after the ion source and the LEBT. The design was finished in 2015 and machining of the accelerator cavity started in 2016. The RFQ is a 4-vane structure, aimed to accelerate protons from 45 keV to 3:0MeV and operating at 352:2MHz in pulsed mode with a duty cycle up to 10%. Total length is about 3:1m divided in 4 segments. Each segment is itself assembled from four components, named vanes, by using polymeric vacuum gaskets with no brazing among them. Notable aspects of the design are the constant mean aperture R0, vane radius ρ and thus ρ/R0 ratio and also uniform inter vane voltage. Novel procedures for the design of the modulation and integrated beam dynamics and electromagnetic design have been developed for this task. In this paper, the complete design procedure and its results are presented, including beam dynamics, RF cavity design, field flatness and frequency tuning, cooling and thermo-mechanical design. [ABSTRACT FROM AUTHOR]

Neutron production with laser-driven neutron sources was demonstrated. We outline the basics of laser-driven neutron sources, highlight some fundamental advantages, and quantitatively compare the neutron production at the TRIDENT laser sources with the well-established LANSCE pulsed neutron spallation source. Ongoing efforts by our team to continue development of these sources, in particular the LANSCE-ina-box instrument, are described. The promise of ultra-intense lasers as drivers for brilliant, compact, and highly efficient particle accelerators portends driving next-generation neutron sources, potentially replacing in some cases much larger conventional accelerators. [ABSTRACT FROM AUTHOR]

We describe the Compact Accelerator-based Neutron Source SONATE which we are aiming for to replace the closed Orphée reactor at Saclay, France. The SONATE source would serve an instrumental suite of about 10 instruments. The instruments would be split into low resolution instruments and higher resolution instruments. Our reference design is based on a proton accelerator operating at an energy in the range 20-30 MeV. The accelerator would serve 2 target stations. The first one operating at 20Hz with 2ms long pulses serving low resolution instruments (SANS, reflectivity, imaging, spin-echo) and the second one operating at 100Hz, 200μs long pulses serving higher resolution instruments (powder diffraction, Direct Time-of-flight spectroscopy, Indirect geometry spectroscopy). The 2 operation modes would be interlaced. The peak current on the target is aimed at 100 mA with an average power on the target on the order of 50-80 kW. Numerical Monte-Carlo simulations show that we may expect instrument performances equivalent to the current instruments around Orphée or ISIS. [ABSTRACT FROM AUTHOR]