Search

nEXO is a proposed search for neutrinoless double beta decay (0vββ) of 136Xe. The experiment is planning to utilize isotopically enriched xenon both as source and detection medium. Radon daughters produced by radon decays in the air can plate out on material surfaces during detector assembly and handling. The alpha particles they emit can interact with low-Z materials nearby and produce fast neutrons. These neutrons can in turn produce 137Xe when captured by 136Xe contained in the nEXO detector medium. The subsequent beta decay of 137Xe (Q = 4173 keV) can mimic 0vββ in nEXO. This paper describes simulation studies performed to estimate the background in nEXO produced by radon daughters. We will also discuss the allowed amounts of radon daughters on material surfaces in order to meet nEXO's stringent background requirements. [ABSTRACT FROM AUTHOR]

The Institute of Nuclear and Physical Engineering is currently developing a special laboratory, the Laboratory of Neutron Applications, where a DD type neutron generator is planned to be purchased and used for research purposes. As the equipment will be installed in a new facility, shielding materials will have to be utilized, to minimize the dose rate obtained by the personnel working with the generator as well as all workers of the faculty, who could potentially get close to the laboratory. The selection of shielding materials is complicated by the fact, that the room is situated partially underground on special pillars with limited load capacity, therefore the used shielding must be light and cheap. In this paper we are comparing the shielding performance of available light materials with the certified Neutronstop shielding blocks, based on the measurement conducted at the STU Mini Labyrinth and simulation performed in the SCALE6 system. The paper includes results of the neutron disappearance XS and the half-value-thickness of selected materials, the dose map around the Mini Labyrinth and a simple economic feasibility estimation for the Laboratory of Neutron Applications. [ABSTRACT FROM AUTHOR]

This paper presents the description of the preparation of aggregate irradiation experiment including the choice of sample types and preliminary numerical prediction of aggregate RIVE and damage under defined conditions for the research reactor LVR-15. Ten different samples from four countries were selected for the experimental investigation. The preliminary numerical analysis was performed for granite as the aggregate with the highest radiation-induced volumetric expansion (RIVE). Based on the prediction, the highest RIVE of 4.54 % at high-dose neutron fluence (0.585·1020 n/cm2, with energy E>10 keV) is expected. Thus, taking into account the sample size, the inner diameter of the irradiated capsule should be about 11 mm. The aggregate samples with the highest RIVE (granite) are expected to be damaged significantly even after irradiation to low-dose neutron fluence (0.208·1020 n/cm2, with energy E>10 keV) which will be captured during the post-irradiation examination. [ABSTRACT FROM AUTHOR]

The ITER Radial Neutron Camera (RNC) is a diagnostic system designed as a multichannel detection system to measure the uncollided neutron flux from the plasma, generated in the tokamak vacuum vessel, providing information on neutron emissivity profile. The RNC consists of array of cylindrical collimators located in two diagnostic structures: the ex-port system and the in-port system. The in-port system, contains the diamond detectors which need a temperature protection. Feasibility study of the efficiency of the cooling system for the In-port Detector Modules of the RNC during baking process was the main goal of thermo-hydraulic numerical modeling. The paper presents the concept of the cooling system layout and the original way of integration of numerical thermo-hydraulic analyses of the in-port detector cassette. Due to the large extent of the detector cassette it is impossible to include all relevant thermal and hydraulic effects in one global model with sufficient level of details. Thus the modelling strategy is based on the concept of three stage modelling from details to global model. The presented paper includes results of numerical calculations made with ANSYS Fluent software in order to provide the final answer, including calculation of heat loads in the detector cassette from adjacent walls during baking and normal operation conditions. [ABSTRACT FROM AUTHOR]

The Mini Labyrinth experiment is a simple neutron and gamma shielding experiment developed at Slovak University of Technology (STU), inspired by the ALARM-CF-AIR-LAB-001 ICSBEP benchmark. Compared to the original Labyrinth, which was made from concrete blocks and had dimension of several meters, the STU Mini Labyrinth is approximately ten times smaller and consists of NEUTRONSTOP shielding blocks. So far, several versions and modifications of the Mini Labyrinth have been investigated, currently the V2-25-L version is used for code evaluation. This version uses a PuBe neutron source loaded in the entrance of the Mini Labyrinth, a plastic tank filled with light water moderator and the NuDET plastic scintillation neutron detector, which can be placed around the experimental workplace. This detector has a significant role in the experiment since it is a calibration apparatus and provides real time data on the rates of ambient dose equivalents of neutron radiation. On the other hand, as it is a certified commercial product, the response function of this detector is unknow, which makes a significant challenge of verifying the measured data with computer codes. This paper presents a result of a series of measurements with the NuDET detector performed at STU and discusses the options, how to verify the experimental results by the SCALE6 system in the most effective way. [ABSTRACT FROM AUTHOR]

This paper presents the theoretical analysis of neutron transfer mechanism for the reaction 181Ta(18O, 19O) at energies 81.86 and 90.05 MeV in the center of mass system. Numerical solution of the time-dependent Schrödinger equation is used for studying neutron transfer processes. The evolution of the wave function for the neutron from the uppermost occupied single-particle neutron level of the 181Ta nucleus is determined. The dynamics of neutron transfer process is described and the probabilities of occupation of initially unoccupied single-particle neutron levels of the 18O nucleus are determined. [ABSTRACT FROM AUTHOR]

The present paper contains investigations of the creep process in the cobalt-based amorphous metallic alloy within the temperature range from 300 up to 1023 K. In all the curves of deformation there were observed jumps and dying oscillations. It is noted that the creep of the sample ribbons is unstable and results in the thinning of ribbons with tightening and crimping. There is suggested the mechanism of inhomogeneous deformation, which takes place in course of the process of creep under intermittent heating. For the evaluation of amorphism in the treated samples there have been carried out neutron-graphical and X-ray diffraction investigations, as well as thermal analysis. [ABSTRACT FROM AUTHOR]

The new solid state track detector analysis system for neutron dosimetry and radon measurement TASLImage™ was installed at the Slovak University of Technology, Bratislava. This paper describes the test of its performance in the measurement of neutron doses. The linearity of the response of poly allyl diglycol carbonate (PADC) detectors was tested for two regions of obtained doses, 27-378 µSv and 0.5 - 3 mSv. Results were compared to H*(10) ambient dose equivalent measured by the NuDET-ENE neutron detector. [ABSTRACT FROM AUTHOR]

This paper examined the fusion of 28Si with 90,96Zr-target by opting the energy dependent Woods-Saxon potential (EDWSP) model and code CCFULL. The CCFULL analysis suggested that for 28Si + 90Zr system, the vibrational excitations of 90Zr-isotope have been found to be very important while for 28Si + 96Zr system, in addition to multiphoton vibrational states of target, the considerations of nucleon transfer are essentially needed for the adequate addressal of the observed fusion data. In contrast, predictions based on EDWSP model appropriately recovered the fusion data of 28Si + 90,96Zr systems at sub-barrier realm. The EDWSP based results do not include various channel coupling effects explicitly but being the energy dependent nature of Woods-Saxon potential (WSP), the calculational results intrinsically incorporate the nuclear effects of the fusing systems. This unambiguously clarified that the energy dependent nature of the EDWSP generates analogous barrier modulations as emerged from the CCFULL analysis. [ABSTRACT FROM AUTHOR]

The paper aims to study the quadrupole deformation and deformation energy curves of , even-even S 50 94 − 168 n isotopes (from the neutron to proton drip lines) which is one of the most interesting isotopic chains in the periodic table. The results are carried out in the framework of the Hartree-Fock-Bogoliubov (HFB) method with the HFB9 Skyrme force by using the HFBTHO code version (3.00) and compared with the available values of Finite Range Droplet Macroscopic model (FRDM), Relativistic Mean Field (RMF) theory. Sn isotopes of A<144 remain robustly spherical till N reaches 144 except for some nuclei where the deformation is quite small. Nuclei above this neutron number show an interesting change to prolate shape. Overall, An agreement is found between our calculations and other models. [ABSTRACT FROM AUTHOR]

The radiation resulting from neutron interactions with Ge nuclei in active volume of HPGe detectors is one of the main concerns in low-level gamma spectroscopy measurements [1,2]. It is usually not possible to measure directly spectrum of neutrons which strike detector. This paper explore the possibility of estimation of neutron spectrum using measured activities of certain Ge(n,γ) and Ge(n,n') reactions (obtained from low-level gamma measurements), available ENDF cross section data and unfolding procedures. In this work HPGe detector with passive shield made from commercial low background lead was used for the measurement. The most important objective of this study was to reconstruct muon induced neutron spectrum created in the shield of the HPGe detector. MAXED [3] and GRAVEL [4] algorithms for neutron spectra unfolding were used. The results of those two algorithms were compared and we analyzed the sensitivity of the unfolding procedure to the various input parameters. [ABSTRACT FROM AUTHOR]

In this paper, some nuclear features of some neutron-rich Al isotopes chain with neutron numbers N=14-22 near the island of inversion N=20 were investigated. The goal of this study was to verify the presence and magnitude of the inversion nature as the number of neutrons increases in these nuclei. For this purpose, the non-relativistic Hartree- Fock (HF) approach based on Skyrme parameterizations in two model space; sd with USDA interaction and sdpf with SDPFMU interaction was used. The results were compared with the available experimental data from NNDC and Ref. [1-3]. They support the validity of both the sd model for 28-32Al with normal ground state configuration, and sdpf model for 33&34Al with intruder ground state configuration. [ABSTRACT FROM AUTHOR]

Cement based composites are considered to be a very important part of the present multi-barrier concepts in nuclear waste management. To assess their suitability in this respect, it is necessary to understand in detail the transport of radionuclides in such composites. One of the tasks is a proper description of adsorption into the pore walls. Usually, an equilibrium isotherm is assumed to well describe the sorption. However, in this paper we introduce a first-order kinetic sorption model to show that it could plausibly interpret experimental data on the transport of gadolinium in a dry cement composite. The data are measured by neutron imaging, and the optimization of model parameters in order to fit the data is based on the Levenberg-Marquardt method. [ABSTRACT FROM AUTHOR]

In the present paper, we have theoretically calculated the nuclear neutron and proton densities, initial exciton numbers and binding energies of the Strontium isotopes (84-96Sr). The Skyrme Hartree Fock (SHF) parameterizations S2, S3, SG2, SKa, SKM, SKM*, and T3 are used in the neutron and proton density calculations. The initial neutron and proton exciton numbers of the 84-96Sr isotopes have been calculated using the SKM* Skyrme parameter. The obtained results from Skyrme force parameters are discussed and compared with each other's and are shown to be in agreement with each other. [ABSTRACT FROM AUTHOR]

Measurement of neutron cross section data is a core activity of the JRC-Directorate G for Nuclear Safety and Security in Geel. After a period of reduced activity and in line with a renewed interest for nuclear data required for GenIV reactors and waste minimization, the demand for high quality actinide targets increased. Physical vapour deposition by thermal evaporation is a key technique to prepare homogeneous thin actinide layers, but due to ageing effects the earlier in-house developed equipment can no longer provide the required quality. Because of a current lack of experience and human resources cooperation with private companies is required for the development of new deposition equipment directly integrated in a glove box. In this paper we describe the design, implementation and validation of the first commercial actinide evaporator in a glove box as well as the optimization of the deposition process. Highly enriched 238U3O8 was converted to 238UF4 powder and several deposition runs were performed on different substrates. The deposition parameters were varied and defined in order to guarantee physical and chemical stable homogeneous UF4 layers, even on polished substrates which was not longer feasible with the older equipment. The stability problem is discussed in view of the thin layer growth by physical vapour deposition and the influence of the deposition parameters on the layer quality. The deposits were characterized for the total mass by means of substitution weighing and for the areal density of 238U by means of alpha particle counting and thermal ionization mass spectrometry (TIMS). The quality of the layer was visually evaluated and by means of stereo microscopy and auto radiography. [ABSTRACT FROM AUTHOR]

The uncertainty in neutron cross section values strongly depends on the quality and characteristics of the deposited actinide films which are used as “targets” in the nuclear experiments. Until recently, at the Joint Research Centre in Geel (JRC-Geel), mass and areal densities of actinide layers were determined by measuring activity (using alpha-particle counting), isotopic composition (using thermal ionisation mass spectrometry) and diameter. In this study a series of 238U deposits, prepared by molecular plating and vacuum deposition on different substrates, were characterized with additional non-destructive and destructive analysis techniques. The quality of the deposits was investigated by autoradiography, high-resolution alpha-particle spectrometry, and scanning electron microscopy. The elemental composition was determined by x-ray photoelectron spectroscopy and inductively coupled plasma mass spectrometry. The latter technique was also applied on the U3O8 starting material and the converted UF4 powder. This paper compares the quality and morphology of deposited 238U films prepared by molecular plating and vacuum deposition on various backings, including their elemental composition determined by different characterization techniques. Also discussed are problems in target preparation and characterization. [ABSTRACT FROM AUTHOR]

Attempts to explain the origin of r-process elements in our Solar System (S.S.) still face entwined uncertainties, stemming from the extrapolation of nuclear structure from the line of β-stability to the neutron drip line, inconsistent sources of different properties (e.g. nuclear masses and β-decay quantities), and the poor understanding of astrophysical conditions, which are often hard to disentangle. In this paper, we will focus on the two interrelated gross β-decay quantities T1/2 and Pn. We compare the recent experimental T1/2 of very neutron-rich isotopes in the 36Kr to 50Sn region (measured at RIKEN) with consistent QRPA(GT+ff) predictions based on the two global deformed mass models ETFSI-Q(1996) and FRDM(2012). Analyzing the observed agreement and remaining deficiencies of the T1/2 trends, we predict the still unknown β-delayed neutron-emission probabilities (Pn) for these isotopes using the empirical Kratz-Herrmann formula (KHF) and the microscopic ETFSI-Q/QRPA(GT+ff) model combination. [ABSTRACT FROM AUTHOR]

In this paper, we use Lee's 5 phase model code to configure both the India Bhabha Atomic Research Center (BARC) Plasma focus machine operating in the pressure (P0) range from 1 Torr to 14 Torr as well as the Imperial College Plasma Focus Machine operating in the pressure (P0) range from 0.5 Torr to 6 Torr to compare the computational neutron yield to the experimental neutron yield as well as to obtain the relationship between axial speed va, radial shock speed vs, piston speed vp and pinch temperature with P0 for these machines. [ABSTRACT FROM AUTHOR]

In this study, source identification problem for the two dimensional neutron transport equation is studied. For the approximate solution of this problem a first order of accuracy difference scheme is presented. Stability inequalities for the solution of these differential and difference problems are established. Numerical results are given. [ABSTRACT FROM AUTHOR]

Current generation light water reactors (LWRs), sodium cooled fast reactors (SFRs), small modular reactors (SMRs), and next generation nuclear plants (NGNPs) produce harsh environments in and near the reactor core that can severely tax material performance and limit component operational life. To address this issue, several Department of Energy Office of Nuclear Energy (DOE-NE) research programs are evaluating the long duration irradiation performance of fuel and structural materials used in existing and new reactors. In order to maximize the amount of information obtained from Material Testing Reactor (MTR) irradiations, DOE is also funding development of enhanced instrumentation that will be able to obtain in-situ, real-time data on key material characteristics and properties, with unprecedented accuracy and resolution. Such data are required to validate new multi-scale, multi-physics modeling tools under development as part of a science-based, engineering driven approach to reactor development. It is not feasible to obtain high resolution/microscale data with the current state of instrumentation technology. However, ultrasound-based sensors offer the ability to obtain such data if it is demonstrated that these sensors and their associated transducers are resistant to high neutron flux, high gamma radiation, and high temperature. To address this need, the Advanced Test Reactor National Scientific User Facility (ATRNSUF) is funding an irradiation, led by PSU, at the Massachusetts Institute of Technology Research Reactor to test the survivability of ultrasound transducers. As part of this effort, PSU and collaborators have designed, fabricated, and provided piezoelectric and magnetostrictive transducers that are optimized to perform in harsh, high flux, environments. Four piezoelectric transducers were fabricated with either aluminum nitride, zinc oxide, or bismuth titanate as the active element that were coupled to either Kovar or aluminum waveguides and two magnetostrictive transducers were fabricated with Remendur or Galfenol as the active elements. Pulse-echo ultrasonic measurements of these transducers are made insitu. This paper will present an overview of the test design including selection criteria for candidate materials and optimization of test assembly parameters, data obtained from both out-of-pile and in-pile testing at elevated temperatures, and an assessment based on initial data of the expected performance of ultrasonic devices in irradiation conditions. [ABSTRACT FROM AUTHOR]

Initially, yields (or abundances) and branching ratios of β-delayed neutrons (βdn) from fission products (Pn-values) have had their main importance in nuclear reactor control. At that time, the six-group mathematical approximation of the time-dependence of βdn-data in terms of the so-called "Keepin groups" was generally accepted. Later, with the development of high-resolution neutron spectroscopy, ßdn data have provided important information on nuclear-structure properties at intermediate excitation energy in nuclei far from stability, as well as in nuclear astrophysics. In this paper, I will present some examples of the βdn-studies performed by the Kernchemie Mainz group during the past three decades. This work has been recognized as an example of "broad scientific diversity" which has led to my nomination for the 2014 Hans A. Bethe prize. [ABSTRACT FROM AUTHOR]

The deuterium Dense Plasma Focus (DPF) can produce copious amounts of MeV neutrons and can be used as an efficient neutron source. However, the mechanism by which neutrons are produced within the DPF is poorly understood and this limits our ability to optimize the device. In this paper we present results from a computational study aimed at understanding how neutron production occurs in DPFs with a current between 70 kA and 500 kA and which parameters can affect it. A combination of MHD and kinetic tools are used to model the different stages of the DPF implosion. It is shown that the anode shape can significantly affect the structure of the imploding plasma and that instabilities in the implosion lead to the generation of large electric fields at stagnation. These electric fields can accelerate deuterium ions within the stagnating plasma to large (>100 keV) energies leading to reactions with ions in the cold dense plasma. It is shown that the electromagnetic fields present can significantly affect the trajectories of the accelerated ions and the resulting neutron production. [ABSTRACT FROM AUTHOR]

A study of asymmetric fission yield behavior from a neutron-deficient Hg isotope has been conducted. The fission yield calculation of the neutron-deficient Hg isotope using Brownian Metropolis shape had showed unusual result at decreasing energy. In this paper, this interesting feature will be validated by using nine degree of scission shapes parameterization from Brosa model that had been implemented in TALYS nuclear reaction code. This validation is intended to show agreement between both model and the experiment result. The expected result from these models considered to be different due to dynamical properties that implemented in both models. [ABSTRACT FROM AUTHOR]

The Mega Ampere Spherical Tokamak Upgrade (MAST Upgrade) is intended as a demonstration of the physics viability of the Spherical Tokamak (ST) concept and as a platform for contributing to ITER/DEMO physics. Concerning physics exploitation, MAST Upgrade plasma scenarios can contribute to the ITER Tokamak physics particularly in the field of fast particle behavior and current drive studies. At present, MAST is equipped with a prototype neutron camera (NC). On the basis of the experience and results from previous experimental campaigns using the NC, the conceptual design of a neutron camera upgrade (NC Upgrade) is being developed. As part of the MAST Upgrade, the NC Upgrade is considered a high priority diagnostic since it would allow studies in the field of fast ions and current drive with good temporal and spatial resolution. In this paper, we explore an optional design with the camera array viewing the poloidal section of the plasma from different directions. [ABSTRACT FROM AUTHOR]

The diagnostic systems of DEMO that are mounted on or near the torus, whether intended for the monitoring and control functions of the engineering aspects or the physics behaviour of the machine, will have to be designed to suit the hostile nuclear environment. This will be necessary not just for their survival and correct functioning but also to satisfy the pertinent regulatory bodies, especially where any of them relate to machine protection or the prevention or mitigation of accidents foreseen in the safety case. This paper aims to indicate the more important of the reactor design considerations that are likely to apply to diagnostics for DEMO, drawn from experience on JET, the provisions in hand for ITER and modelling results for the wall erosion and neutron damage effects in DEMO. [ABSTRACT FROM AUTHOR]

Neutrons can induce background events in underground experiments looking for rare processes. Neutrons in a MeV range in deep underground laboratories are produced in spontaneous fission processes and (α, n) reactions. A number of computer codes are available to calculate cross-sections of (α, n) reactions, branching ratios to various states and neutron yields. We have used the SOURCES4 code to calculate neutron yields and energy spectra with input cross-sections and branching ratios taken from experimental data and calculations based on EMPIRE2.19/3.2.3 and TALYS1.9. We report here a comparison of SOURCES4 calculations with experimental data obtained with alpha beams with fixed energies. [ABSTRACT FROM AUTHOR]

To license the advanced gas-cooled fast reactor design, sufficient data with associated uncertainties should be known about its safety and operational capability. The relevant core parameters intuitively depend on the actual fuel isotopic composition which develops during a reactor operation. In practice, the prediction accuracy of burnup calculations serves as the basis for the future precise estimation of a core lifetime and other safety-based core characteristics. The present study quantifies nuclear data induced uncertainties of nuclide concentrations and multiplication factors in GFR 2400 demonstrator ALLEGRO utilizing the SCALE system, where the TRITON sequence is used with the KENO stochastic solver. The super-sequence SAMPLER module that implements stochastic techniques is used to assess the uncertainty in computed results. The propagation of uncertainties in neutron cross-section and fission yields is studied through the depletion calculation of 2D heterogeneous ALLEGRO-MOX fuel, where 150 cases with uncertain parameters are computed and the results are evaluated by an auxiliary tool. Achieved results confirmed the high final uncertainties in multiplication factor and nuclide concentrations important for criticality safety (239Pu, 238U, 241Pu) and decay heat (241Am) production. [ABSTRACT FROM AUTHOR]

This paper summarizes a Photomultiplier-Scintillator diagnostic system for use in our plasma focus experiments at the Center for Plasma Research INTI IU. The system features an anode-grounded high pulse linearity voltage divider and uses NE102A plastic scintillators. It has detected D-D neutrons in INTI plasma focus device with clear and high signal to noise ratio. Neutron TOF of 120 ns has been measured from the time difference between hard x-ray pulse peak and neutron peak time over a flight path of 2.6±0.01 m; giving energy of 2.5±0.1 MeV for these side-on neutrons. [ABSTRACT FROM AUTHOR]

This study demonstrates some nuclear properties that have been calculated of 58-60Ni nuclei such as positive energy levels ,electric quadrupole transitions, intrinsic quadrupole moment and factors of deformation. Nushell@MSU code was utilized for f5p model space with Van Hienen - Chung -Wildenthal (f5pvh) interaction. The calculations are carried out by utilizing three sets of effective charges obtained from Bohr - Mottelson model also default and appropriate effective charges for valance nucleons(protons and neutrons). A comparison has been made between theoretic effects with the available experimental data. The comparison shows that the energy levels , transition probabilities, intrinsic quadrupole moment and quadrupole deformation parameter are agreed well especially at effective charges of Bohr - Mottelson model and appropriate effective charges. [ABSTRACT FROM AUTHOR]

The author discusses some of the challenges that future nuclear modeling may face in order to improve the description of the nuclear structure. One challenge is related to the need for A-body nuclear interactions justified by various contemporary nuclear physics studies. Another challenge is related to the discrepancy in the NNN contact interaction parameters for 3He and 3H that suggests the need for accurate proton and neutron masses in the future precision calculations. [ABSTRACT FROM AUTHOR]

Since neutrons at certain energies colliding with fissile nuclei may cause them to undergo Fission reaction by splitting them, new neutrons are produced at high energies but certain amount of fissile material is required for a sustainable chain reaction by these high energetic neutrons. It is required to determine the amount of mass necessary for a Fission chain reaction since the procedure is completely random for neutrons to strike target nuclei. It is known that the critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction in any system. It is obvious that the critical mass of a fissionable material depends upon its nuclear properties, such as its fission cross-section, its density, its shape, its enrichment, its purity, etc. In this study, the Monte Carlo Method is studied to calculate the critical mass for three basic geometries. The survival fraction value is determined for the criticality condition for geometries and is compared, respectively. All calculations are also repeated for sphere with a reflector. Analytical and numerical results are compared. A conclusion is presented. [ABSTRACT FROM AUTHOR]

The present work is based on the extensive evaluation of the gamma-radiation and neutron shielding ability of synthesized Sb2O3-based multicomponent heavy metal oxide glasses in the form of xSb2O3.yWO3.zPbO.10Na2O system (where z=10-40 mol%, x/y=6 and x+y+z=90). The shielding properties have been evaluated using both Hubbell and Seltzer and Boone and Chavez database with the help of XCOM and XMuDat programs. Shielding ability from gamma rays has been assessed from several parameters including mass attenuation coefficient, tenth-value layer, effective atomic number and effective electron density. As compared to the common nuclear reactor shielding concretes (ordinary and barite) and commercially available shielding glass RS 360, our studied glasses have provided much better results. Low values of exposure buildup factor indicate good shielding behaviour of the glasses. The glasses also have superior neutron shielding properties than the commonly used neutron shields (Boron Carbide, Polyacrylic Acid and Graphite). The investigated glass system require lesser volume for shield design owing to its better gamma-ray and neutron shielding properties as well as transparency to visible light. The investigated Sb2O3-based multicomponent heavy metal oxide glasses have the potential to be utilized as transparent see-through radiation shielding material in several nuclear and medical applications to shield the radiation workers from excessive radiation exposure. [ABSTRACT FROM AUTHOR]

The diffusion length L of thermal neutrons has been measured in demi water at room temperature using an PuBe source. The brief theory is outlined, and the results of neutron activation analysis are compared with a first measurement performed by Helium-3 neutron detector. The efforts made are the part of the complex approach aiming to validate nowadays computational tools and methods with measured parameters. [ABSTRACT FROM AUTHOR]

In this presentation the possible existence of bound states made of neutrons and Λ hyperons will be discussed. Strong arguments will be given to show that the systems Λnn (³Λn) and ΛΛnn (4Λn) do not possess bound states. This will be done by reviewing the work of several theoretical groups. [ABSTRACT FROM AUTHOR]

The glue-like behavior of valence neutrons has been investigated in the Li isotopes. The 7Li nucleus is well known to be weakly bound system with the α + t cluster structure. By adding the valence neutrons, the reduction of the root-mean-square (RMS) radius of the proton density for the 7Li, 8Li and, 9Li nuclei is also well known from the viewpoint of the experimental data and theoretical approach. Elastic scattering cross sections of the Li isotopes on the 12C and 28Si targets at E/A～50 MeV are calculated. We find the change of the channel coupling (CC) effect on elastic scatterings of such Li isotopes by the glue-like role of the valence neutrons. Finally, we realize that the valence neutrons stabilize the binding of core parts, and the CC effect related the core excitation is indeed reduced. [ABSTRACT FROM AUTHOR]

We have investigated the Gamow-Teller transitions from 10Be(0+ 1 1) →10B(1+0) and 22Ne(0+ 1 1) → 22Na(1+0) by using the isospin projected antisymmetrized molecular dynamics combined with the generator coordinate method (T βγ-AMD+GCM). We have found that the fragmentation of GT strength in 22Ne(0+ 1 1) → 22Na(1+0) can be explained by introducing K-bands originated from a S = 1 proton-neutron (pn) pair in the prolately deformed 20Ne core. The SU(4)-symmetry breaking of the pn pair into S z = 0 and S z = ±1 plays an important role in this GT fragmentation. We have discussed the link of the SU(4)-symmetry and the GT fragmentation in the deformed systems by artificially changing the spin-orbit interaction on the GCM calculation. [ABSTRACT FROM AUTHOR]

We investigate resonance states in three-cluster continuum of some light nuclei 9Be, 9B, 10B, 11B and 11C. These nuclei are considered to have a three-cluster configuration consisting of two alpha-particles and neutron, proton, deuteron, triton and nucleus 3He. In this study, we make use two different microscopic three-cluster models. The first model employs the Hyperspherical Harmonics basis to numerate channels and describe three-cluster continuum. The second model is the well-known complex scaling method. Our main aim is to find the Hoyle-analog states in these nuclei or, in other words, whether it is possible to synthesize these nuclei in a triple collision of clusters.We formulate the criteria for selecting such states and apply them to resonance states, emerged from our calculations. We found that there are resonance states obeying the formulated criteria which make possible syntheses of these nuclei in a stellar environment. [ABSTRACT FROM AUTHOR]

Linear-chain and gas-like structures have been investigated in nuclei near 12C by using antisymmetrized molecular dynamics combined with generator coordinate method. We found that linear-chain structures and gas-like structures of three clusters exist quite universally. 10Be, 11B, and 12C have gas-like states of 2α+dineutron, 2α+t, and 3α structures, respectively. There are linear-chain states, in which 2α clusters are formed and valence nucleons occupy the σ-orbit. In neutron-rich C isotopes, linear- chain structures of three α clusters surrounded by excess neutrons appear. Excess neutrons stabilize the linear chain structures, and therefore, linear-chain states appear below the 3α+Xn threshold energy. In 14C, candidates of the linear-chain states are observed in recent 10Be+α resonant scattering experiments. [ABSTRACT FROM AUTHOR]

Coherent photoproduction of π0-meson from the deuteron near π0-production threshold is investigated with special emphasize on single polarization observables. We report numerical results for the linear photon asymmetry Σ and tensor deuteron spin asymmetries T2M (M=0,1,2). The sensitivity of obtained results to the D-state contribution in the deuteron wave function of realistic NN potentials is studied. It is shown that the influence of D-state contribution on the predicted spin observables is sizable, and it provides important constraints for the extraction of the elementary neutron amplitude. Compared with the experimental data from TAPS collaboration for differential cross section, we obtain a satisfactory agreement. [ABSTRACT FROM AUTHOR]

Polarization observables in the reaction γd → π0d near η-threshold with inclusion of rescattering effects are investigated. This work is motivated by the recent measurements for the tensor target spin asymmetry T20 from the VEPP-3 electron storage ring at Novosibirsk. Numerical results for the spin asymmetries T2m (m=0,1,2) for tensor polarized deuterons and unpolarized photons are presented. It is shown that the influence of rescattering effects on the tensor target spin asymmetries is sizable, specially at extreme backward direction. We also compare our results with the recent measurements from VEPP-3, and find good agreement with data. [ABSTRACT FROM AUTHOR]

SARAF (Soreq Applied Research Accelerator Facility) is based on a 5 mA, 40 MeV, proton/deuteron accelerator. Phase-I, operational since 2010, provides proton and deuteron beams up to 4 and 5 MeV, respectively, for basic and applied research activities. The high power Liquid-Lithium jet Target (LiLiT), with 1.912 MeV proton beam, provides high flux quasi-Maxwellian neutrons at kT ~30 keV (about 2 × 1010 n/s/cm2/mA on the irradiated sample, about 1 cm from the target), enabling studies of s-process reactions relevant to nucleo-synthesis of the heavy elements in giant AGB stars. With higher energy proton beams and with deuterons, LiLiT can provide higher fluxes of high energy neutrons up to 20 MeV. The experimental program with SARAF phase-I will be enhanced shortly with a new target room complex which is under construction. Finally, SARAF phase-II, planned to start operation at ~2023, will enable full capabilities with proton/ deuteron beams at 5 mA and 40 MeV. Liquid lithium targets will then be used to produce neutron sources with intensities of 1015 n/s, which after thermalization will provide thermal neutron (25 meV) fluxes of about 1012 n/s/cm2 at the entrance to neutron beam lines to diffraction and radiography stations. [ABSTRACT FROM AUTHOR]

Abstract. Heavy ion fusion reactions play important roles in a wide variety of stellar burning scenarios. 12C+12C, 12C+16O and 16O+16O are the principle reactions during the advance burning stages of massive star. 12C+12C also triggers the happening of superburst and Type Ia supernovae. The heavy ion fusion reactions of the neutron-rich isotopes such as 24O are the major heating source in the crust of neutron star. In this talk, I will review the challenges and the recent progress in the study of these heavy ion fusion reactions at stellar energies. The outlook for the studies of the astrophysical heavy-ion fusion reactions will also be presented. [ABSTRACT FROM AUTHOR]

Kaon photoproduction processes γp → K+Λ and γn → K0 Λ have been investigated in the energy regime from threshold up to W = 2 0 GeV. The K+Λ background amplitude is constructed from the appropriate Feynman diagrams, whilst the resonance terms were obtained by using the multipole approach. The observables for the K0 Λ channel are obtained by imposing the isospin symmetry to the K+Λ channel and using some experimental data on the helicity photon amplitudes for neutron obtained from the Particle Data Group. The observables used in the present investigation are the cross section and polarization observables. In the case of K+Λ channel, the agreement with the experiment data has been achieved. In the case of K0Λ channel, the predicted observables indicate significant discrepancies with the prediction of Kaon-Maid. [ABSTRACT FROM AUTHOR]

Proton-neutron (pn) correlations in nuclei above the Z=50 shell closure are investigated in order to understand the peculiar behaviour of the 2+ and 4+ states in Te and Xe isotopes. It turns out that by increasing the pn pairing interaction, which becomes important for N ≈ Z nuclei, the collectivity decreases. We thus conclude that the ratio between the B(E2) value and 2+ energy is a "fingerprint" of pn collectivity. The available experimental data indeed indicate an enhanced pn pairing interaction by also approaching double magic Z=N=20 and Z=N=28 regions. It is known that the α-particle reduced width has the largest values in the region above 100Sn. In order to reproduce the reduced α-decay width we use an additional pocket-like surface potential in the single particle mean field, simulating four-body correlations. The strength of this interaction has a universal linear dependence on the experimental reduced width above the double magic nuclei 100Sn and 208Pb. Moreover, we demonstrate that pn pairing correlations have a small influence on this dependence and therefore cannot explain the larger reduced decay widths above 100Sn. [ABSTRACT FROM AUTHOR]

In this work, preliminary results of MNA-PF device as a Slow Focus Mode device are presented. Four different kinds of Rogowski Coils which have been designed and constructed for dI/dt signals measurements show that response frequency of Rogowski Coil can affect signal time resolution and delay which can change the discharge circuit inductance. Experimental results for 10 to 20 mbar Deuterium and 0.5 mbar to 6 mbar Argon which are captured by 630 MHz Rogowski coil in correlation with Lee Model Code are presented. Proper current fitting using Lee Model Code shows that the speed factor for MNA-PF device working with 13 mbar Deuterium is 30 kA/cm.torr1/2 at 14 kV which indicates that the device is operating at slow focus mode. Model parameters fm and fmr predicted by Lee Model Code during current fitting for 13 mbar Deuterium at 14kV were 0.025 and 0.31 respectively. Microspec-4 Neutron Detector was used to obtain the dose rate which was found to be maximum at 4.78 uSv/hr and also the maximum neutron yield calculated from Lee Model Code is 7.5E+03 neutron per shot. [ABSTRACT FROM AUTHOR]

Surface diffuseness parameter used in Woods-Saxon form of potential have been extracted from a large number of experimentally studied neutron-rich fusion cross sections at near barrier energies. The results of our systematic study reveals that the extracted diffuseness parameter depend linearly on the N/Z ratio of the fusing nuclei. Further, we demonstrated that the extracted values of surface diffuseness parameter lies within the range a = 0.40 to 0.77 fm as compared to commonly accepted value form scattering i.e. 0.63 fm. [ABSTRACT FROM AUTHOR]

The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at 100Sn, through 10 stable isotopes and the N = 82 shell closure at 132Sn out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich 130Sn. Both techniques rely on selective particle identification and the measurement of rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications. [ABSTRACT FROM AUTHOR]

The brilliant gamma beam at the future Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility will be used to generate a beam of exotic neutron-rich isotopes via photofission ofactinide targets. We present simulations with the Geant4 toolkit ofthe photofission process for the design and optimization ofthe expected performance parameters ofthe Cryogenic Stopping Cell (CSC). The CSC will be used to extract the photofission fragments into the secondary beam of about 106 ions/s. We propose an experimental program to study refractory neutron-rich isotopes. [ABSTRACT FROM AUTHOR]

The development of fusion energy is one of the important International energy strategies with the important milestone is ITER (International Thermonuclear Experimental Reactor) project, initiated by many countries, such as: America, Europe, and Japan who agreed to set up TOKAMAK type fusion reactor in France. In ideal fusion reactor the fuel is purely deuterium, but it need higher temperature of reactor. In ITER project the fuels are deuterium and tritium which need lower temperature of the reactor. In this study tritium for fusion reactor can be produced by using reaction of lithium with neutron in the blanket region. With the tritium breeding blanket which react between Li-6 in the blanket with neutron resulted from the plasma region. In this research the material used in each layer surrounding the plasma in the reactor is optimized. Moreover, achieving self-sufficiency condition in the reactor in order tritium has enough availability to be consumed for a long time. In order to optimize Tritium Breeding Ratio (TBR) value in the fusion reactor, there are several strategies considered here. The first requirement is making variation in Li-6 enrichment to be 60%, 70%, and 90%. But, the result of that condition can not reach TBR value better than with no enrichment. Because there is reduction of Li-7 percent when increasing Li-6 percent. The other way is converting neutron multiplier material with Pb. From this, we get TBR value better with the Be as neutron multiplier. Beside of TBR value, fusion reactor can analyze the distribution of neutron flux and dose rate of neutron to know the change of neutron concentration for each layer in reactor. From the simulation in this study, 97% neutron concentration can be absorbed by material in reactor, so it is good enough. In addition, it is required to analyze spectrum neutron energy in many layers in the fusion reactor such as in blanket, coolant, and divertor. Actually material in that layer can resist in high temperature and high pressure condition for more than ten years. [ABSTRACT FROM AUTHOR]

Neutron radiation is able to determine the signature of land mine detection based on backscattering energy spectrum of landmine. In this study, the Monte Carlo simulation of backscattered fast neutrons was performed on four basic elements of land mine; hydrogen, nitrogen, oxygen and carbon. The moderation of fast neutrons to thermal neutrons and their resonances cross-section between 0.01 eV until 14 MeV were analysed. The neutrons energies were divided into 29 groups and ten million neutrons particles histories were used. The geometries consist of four main components: neutrons source, detectors, landmine and soil. The neutrons source was placed at the origin coordinate and shielded with carbon and polyethylene. Americium/Beryllium neutron source was placed inside lead casing of 1 cm thick and 2.5 cm height. Polyethylene was used to absorb and disperse radiation and was placed outside the lead shield of width 10 cm and height 7 cm. Two detectors were placed between source with distance of 8 cm and radius of 1.9 cm. Detectors of Helium-3 was used for neutron detection as it has high absorption cross section for thermal neutrons. For the anomaly, the physical is in cylinder form with radius of 10 cm and 8.9 cm height. The anomaly is buried 5 cm deep in the bed soil measured 80 cm radius and 53.5 cm height. The results show that the energy spectrum for the four basic elements of landmine with specific pattern which can be used as indication for the presence of landmines. [ABSTRACT FROM AUTHOR]