Lithium Target Research Articles

Cross section determination for TAD materials in quasi mono-energetic neutron spectrum from p(Li) reaction

Threshold activation detectors (TAD) are of great importance for a determination of neutron energy spectra and flux density. For different sources, it is necessary to choose the right combination of materials that cover the estimated spectra. Several different materials were irradiated in a quasi-monoenergetic neutron field with 29.1 MeV peak neutrons energy in the CANAM facility. Neutrons were produced in p + Li-7 reaction in a thin target and the foils were situated in the proton beam axis and close geometry to the Li target. The integral number of protons was established from accelerator telemetry and lithium target activation measurements after the experiment. During the experiment, one long irradiation was done for following foils: Al, Au, Bi, Co, Cu, Fe, In, Mn, Pb, Ta, V, Y and four short irradiations for foils: Cu, Fe, In, Ta, V, W, Y. The foils were irradiated in a sandwich configuration, sorted by cross-section where the materials with higher cross-section were placed in the back of the sandwich. Neutrons produced in the p + Li-7 reaction have a quasi mono-energetic spectrum which provides a suitable basis for cross-section determination. Experimental results were calculated for (n,xn), (n,p) and (n,α) reactions via the dosimetry foils activation method including a gamma-ray spectroscopy method. Several important spectroscopic corrections have to be applied to increase the accuracy of the obtained results, including neutron background suppression. Experimental data will be submitted to the EXFOR database.

A 50 kW Liquid-Lithium Target for BNCT and Material-Science Applications

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.

Novel target design for a laser-driven aneutronic fusion reactor

This paper discusses the suitability of proton sources and the appropriate targets for lithium-proton and boron-proton fusion reactions. Protons are emitted by a hydrogen-based source that is exposed to an intense laser beam. The protons are sent onto lithium or boron targets where fusion reactions are triggered. A comparison is made between solid, liquid and gaseous proton sources and the required laser intensity. Furthermore, the main characteristics of the lithium and boron targets are assessed. It is shown that a hybrid target made of lithium and boron offers opportunities to considerably enhance the fusion yield.

AKT1 and genetic vulnerability to bipolar disorder

AKT1 encodes a serine/threonine kinase that has as one of its best-known substrates glycogen synthase kinase-3 (GSK3), a primary target for lithium. AKT1 has been previously been implicated as a vulnerability gene for bipolar disorder (BD). We aimed to associate genetic variants in the AKT1 gene with subgroups of BD. BD patients from a Swedish cohort (N = 831) were phenotyped in regards to their psychotic episodes according to mood-congruence in depression and manias, and compared to controls (N = 1,496). All participants were genotyped for SNPs in AKT1 previously implicated to have a role: rs3730358, rs1130214 and rs3803300. None of the effects reported in earlier studies were statistically significant, including the association between rs3803300 and BD without any psychotic symptoms, rs3803300 and mood-congruent psychosis, rs3803300 and the combined groups, as well as the association between the haplotypes formed by rs3730358 and rs1130214 and risk for BD. In a Bayesian analysis, all Bayes’ Factors using default priors supported the null hypothesis in the replication set by a factor of between 5 and 1300 times. Analysis of genome wide association data did not reveal any association between BD and the AKT1 region. We conclude AKT1 is less likely to be a vulnerability gene in BD.

How does the mood stabilizer lithium bind ATP, the energy currency of the cell: Insights from solid-state NMR

BackgroundLithium, in the form of a salt, is a mood stabilizer and a leading drug for the treatment of bipolar disorder. It has a very narrow therapeutic range and a variety of side effects. Lithium can replace magnesium and other cations in enzymes and small molecules, among them ATP, thereby affecting and inhibiting many biochemical pathways. The form of binding of lithium ions to ATP is not known. MethodsHere we extract the binding environment of lithium in solid ATP using a multi-nuclear multi-dimensional solid-state NMR approach. ResultsWe determine that the coordination sphere of lithium includes, at a distance of 3.0(±0.4) Å, three phosphates; the two phosphates closest to the ribose ring from one ATP molecule, and the middle phosphate from another ATP molecule. A water molecule most probably completes the fourth coordination. Despite the use of excess lithium in the preparations, sodium ions still remain bound to the sample, at distances of 4.3–5.5 Å from Li, and coordinate the first phosphate and two terminal phosphates. ConclusionsSolid-state NMR enables to unravel the exact coordination of lithium in ATP showing binding to three phosphates from two molecules, none of which are the terminal gamma phosphate. General significanceThe methods we use are applicable to study lithium bound to a variety of ATP-bound enzymes, or to other cellular targets of lithium, consequently suggesting a molecular basis for its mode of action.

The first neutron time-of-flight line in Spain: Commissioning and new data for the definition of a neutron standard field

The National Accelerator Laboratory (CNA) has developed the first accelerator line in Spain devoted to the measurement of cross sections involving neutrons by means of the time-of-flight technique. For neutron generation, pulsed proton beams with 1 nsec pulse width and with variable repetition rates are delivered. The data acquisition has been built using a CAEN Digitizer. The aim of this work is to demonstrate the good performance of the time-of-flight system. The commissioning of the line has consisted of the measurement of the neutron field generated by protons at 1912 keV impinging on a thick lithium target. Such a field has been extensively used in nuclear astrophysics since 1988. Recently, there have been experimental works with the goal to support it as a standard neutron field. The results show the good performance of the time-of-flight system and also support its possible definition as a standard.

Development of a downsized proton accelerator system for compact neutron sources

In order to facilitate the widespread use of neutrons in industrial applications, it is important to provide a compact, semi-ready-made neutron source that a company and a factory can easily install. We are therefore developing a compact neutron source system utilizing a downsized proton accelerator as an entry level model for industrial use and materials development, which consists of a proton source, a four-vane radio frequency quadrupole linear accelerator (RFQ) and a lithium target for neutron production by the Li(p,n)37Be47 reaction. An RFQ is suitable to accelerate protons in the low energy region because it accepts DC beams extracted from the proton source and accelerates effectively to the design energy with bunching and focusing using the electric fields. Furthermore, it is possible to design the RFQ with a higher frequency than conventionally used owing to technological advances in high power solid-state RF amplifiers. We investigated the specifications for 500 MHz and 650 MHz through beam trajectory and electromagnetic simulations and fabricated a 2.5 MeV prototype of the 500 MHz type with a 2.45 GHz ECR proton source.

Lithium acts to modulate abnormalities at behavioral, cellular, and molecular levels in sleep deprivation-induced mania-like behavior.

Ample amount of data suggests role of rapid eye movement (REM) sleep deprivation as the cause and effect of mania. Studies have also suggested disrupted circadian rhythms contributing to the pathophysiology of mood disorders, including bipolar disorder. However, studies pertaining to circadian genes and effect of lithium treatment on clock genes are scant. Thus, we wanted to determine the effects of REM sleep deprivation on expression of core clock genes and determine whether epigenetics is involved. Next, we wanted to explore ultrastructural abnormalities in the hippocampus. Moreover, we were interested to determine oxidative stress, tumor necrosis factor-α (TNF-α), and brain-derived neurotrophic factor levels in the central and peripheral systems. Rats were sleep deprived by the flower pot method and were then analyzed for various behaviors and biochemical tests. Lithium was supplemented in diet. We found that REM sleep deprivation resulted in hyperactivity, reduction in anxiety-like behavior, and abnormal dyadic social interaction. Some of these behaviors were sensitive to lithium. REM sleep deprivation also altered circadian gene expression and caused significant imbalance between histone acetyl transferase/histone deacetylase (HAT/HDAC) activity. Ultrastructural analysis revealed various cellular abnormalities. Lipid peroxidation and increased TNF-α levels suggested oxidative stress and ongoing inflammation. Circadian clock genes were differentially modulated with lithium treatment and HAT/HDAC imbalance was partially prevented. Moreover, lithium treatment prevented myelin fragmentation, disrupted vasculature, necrosis, inflammation, and lipid peroxidation, and partially prevented mitochondrial damage and apoptosis. Taken together, these results suggest plethora of abnormalities in the brain following REM sleep deprivation, many of these changes in the brain may be target of lithium's mechanism of action.

Perspectives for the liquid lithium and tin targets in the Italian Divertor Test Tokamak (I-DTT) divertor

The behaviour of the scrape-off plasma of the projected Italian tokamak I-DTT is analysed by means of the two-dimensional edge code TECXY for either Li or Sn as the liquid target material. A scan in the outer midplane separatrix density range ne,omp ≈ (0.5–1.1) × 1020 m−3 is carried out for several power inputs into the scrape-off layer (SOL) up to a maximum of PSOL = 35 MW. The radiative capability and peak load mitigation are higher for Sn than for Li, but only slightly so at high density, so that the entire density range can be explored with liquid Sn targets, unlike Li whose employment at low density and high power is questionable. However, if a ceiling to the Sn concentration is set for high core fusion performance, Sn mitigation at low density may drop below Li. Nonetheless, concerns about the Li option derive from the very large material consumption and from the fact that the main mechanism of impurity release is sputtering, which is outside the full control of the operator. Considering specifically the three main scenarios—low, medium and high density—at the maximum auxiliary power of 45 MW, operations are successful with Sn, whereas Li requires an additional impurity able to radiate in the core, except at the highest density. The snowflake plus configuration, compared with the standard single null, as a sample for advanced divertors, appears more suited to exploit the advantages of the liquid metal option. Concerning additional impurities, only Ar and Ne are considered at present. They can strongly help in reaching and studying deep detached conditions even at the maximum power, but are not essential for operations. Wide flexibility in designing the target refrigeration system is required to fully exploit its great potential.

Astrocytes are direct cellular targets of lithium treatment: novel roles for lysyl oxidase and peroxisome-proliferator activated receptor-\u03b3 as astroglial targets of lithium

Astrocytes are multifunctional glial cells that play essential roles in supporting synaptic signalling and white matter-associated connectivity. There is increasing evidence that astrocyte dysfunction is involved in several brain disorders, including bipolar disorder (BD), depression and schizophrenia. The mood stabiliser lithium is a frontline treatment for BD, but the mechanisms of action remain unclear. Here, we demonstrate that astrocytes are direct targets of lithium and identify unique astroglial transcriptional networks that regulate specific molecular changes in astrocytes associated with BD and schizophrenia, together with Alzheimer’s disease (AD). Using pharmacogenomic analyses, we identified novel roles for the extracellular matrix (ECM) regulatory enzyme lysyl oxidase (LOX) and peroxisome proliferator-activated receptor gamma (PPAR-γ) as profound regulators of astrocyte morphogenesis. This study unravels new pathophysiological mechanisms in astrocytes that have potential as novel biomarkers and potential therapeutic targets for regulating astroglial responses in diverse neurological disorders.

The preliminary conceptual design of the high-power neutron converter for BISOL

Beijing Isotope-Separation-On-Line neutron-rich beam facility (BISOL) is proposed as a double drive radioactive ion beams (RIBs) facility using both a nuclear reactor and a deuteron linear accelerator. The accelerator driven neutron source will be a so called IFMIF-like intense neutron source. To satisfy the requirement of neutron production from a 40 MeV, 50 mA (corresponding to 2 MW) deuteron beam, a windowless liquid lithium target has been adopted as the high-power neutron converter for this facility. The preliminary conceptual design of the target is described. Hydraulic and thermodynamic calculations have been carried out using computational fluid dynamics (CFD) method. The lithium fluid stability and the impact of beam momentum transfer are discussed.

Measurement of the differential cross sections of natLi(d,d0) for EBS purposes

In the present work, the 6,7Li(d,d0)6,7Li elastic scattering differential cross sections were measured in the energy range Elab = 900 – 2000 keV for EBS purposes, using thin lithium targets, made by evaporating natLiF and isotopically enriched 6LiF powder on self-supporting carbon stripping foils, with an ultra-thin Au layer on top for charge normalization purposes. The experiment was carried out in deuteron beam energy steps of 5 to 30 keV, depending on the fine structure of each studied cross section, and for the laboratory scattering angles of 125˚, 140˚, 150˚, 160˚, and 170˚.

Power handling and vapor shielding of pre-filled lithium divertor targets in Magnum-PSI

To develop realistic liquid lithium divertors for future fusion reactors, this paper aims to improve the understanding of their power handling capabilities. A liquid lithium divertor target prototype, designed to facilitate liquid metal experiments in tokamaks, was tested in Magnum-PSI. The target has an internal reservoir pre-filled with lithium and aims to passively re-supply the textured plasma facing surface during operation. To assess the power handling capability the target was exposed to helium plasmas with increasing power flux density in the linear plasma device Magnum-PSI. The temperature response of lithium targets was recorded via an infrared camera, and compared to finite element method modeling taking into account dissipation via lithium in the plasma. It was found that the target works as intended and can take up to 9 1 MW m−2 for 10 s before the mesh layer was damaged, and could continue operating at higher power densities even after being damaged. The total lifetime of the targets was up to 100 s. Overall the targets are found suitable for use in tokamak experiments. Additionally, a central surface temperature evolution indicative of vapor shielding was observed on intact targets. Predicting the target temperature (and consequently the evaporation rates and thermal stresses) is considered very relevant for the design of lithium divertor targets for DEMO. The observed temperature response could indeed be replicated through modeling, which showed that a significant power fraction was dissipated by the lithium in the plasma.

Development of an electrochemical sensor for hydrogen detection in liquid lithium for IFMIF-DONES

Hydrogen impurities in liquid lithium have a drastic disadvantageous impact on the used structural materials. Such a problem might occur also in the planned materials testing facility IFMIF-DONES, where hydrogen isotopes are produced by a reaction of a deuteron-beam with a target of liquid lithium. Therefore, the operation of such a Li-system requires the measurement of hydrogen (seen as impurity in the Li-melt) and the control of hydrogen removal. It is one of the excellences of the tool Electrochemistry to measure dissolved species over wide ranges of concentrations in real-time conditions. This presentation will present the physical background of determining non-metallic impurities in molten metals by measuring electrochemical potentials, outlining the development of such an H-sensor system and the transformation by Nernst correlation into concentration values. Additionally, liquid lithium is a very reactive melt, thus material compatibility is an essential topic for the developments of a durable sensor. Based on these issues a sensor design for measuring hydrogen in liquid lithium was realized under consideration of all physical, chemical and metallurgical aspects, including the successful manufacturing of the sensor as a first prototype and a further first production series. The outlook will also deal with the possibility of measurements of different hydrogen isotopes.

The design of the DONES lithium target system

In the framework of the EU fusion roadmap implementing activities, an accelerator-based Li(d,xn) neutron source called DONES (Demo-Oriented early NEutron Source) is being designed within the EUROfusion Work Package Early Neutron Source as an essential irradiation facility for testing candidate materials for DEMO reactor and future fusion power plants. DONES will employ a high speed liquid lithium jet struck by a 125 mA, 40 MeV deuteron beam to generate the intense neutron flux used to irradiate the material samples up to the desired level of displacement damage (˜10 dpa/fpy for iron in 0.3 l) and He production rates (˜10-13 appm He/dpa).In order to rapidly achieve a sound and stable design, a new configuration of the DONES target system based on the so-called integral concept has been proposed as reference solution in place of the former baseline design that envisaged a target assembly endowed with a replaceable back-plate, being the latter solution not yet fully qualified and thus not readily implementable.Moreover, following the outcomes of detailed dedicated analyses taking into account different aspects, the design of several components (Quench Tank, Lithium inlet pipe, Vacuum Chamber, etc.) has been changed.In this paper, a brief description of the current design of the DONES Target System is presented including all the above-mentioned aspects, showing the capability of the system to fulfil the prescribed requirements.

SU60 - MOLECULAR STUDIES OF THE ANKRYIN3 BIPOLAR DISORDER GWAS GENE IMPLICATE A ROLE IN MICROTUBULE DYNAMICS

Background Ankyrin3 has been identified as a risk gene for Bipolar Disorder (BD) and autism spectrum disorders by multiple genome-wide and targeted association studies as well as sequencing studies. Carriers of the BD risk alleles have reduced ankyrin3 expression in the brain, suggesting that ankyrin3 suppression contributes to disease. However, the mechanism through which ankyrin3 confers risk is unknown. Ankyrin3 encodes the ankyrinG protein that tethers integral membrane proteins to the cytoskeleton. We previously reported that Ank3+/- heterozygous mice, which have ~50% reduced ankyrinG in the brain, exhibit behavioral changes reminiscent of bipolar mania (impulsivity, increased motivation for reward), and altered expression of proteins involved in neuron axonal transport. Both the behavioral and protein expression changes in Ank3+/- mice are normalized by lithium treatment, supporting the disease relevance of these findings. This study sought to further examine the molecular mechanism underlying the behavioral and neuronal changes induced by ankyrin3 suppression in brain. Methods We performed RNA sequencing of hippocampus from Ank3+/- heterozygous and Ank3+/+ wildtype mice, followed by identification of differentially expressed genes using the Tuxedo package. Biological pathways implicated by RNAseq analysis were verified by Western blot of hippocampal protein and live cell imaging of forebrain primary neurons. CRISPR/dCas9 technology was used to repress ankyrin3 transcription in a mouse neuronal system in order to conduct in-depth biochemical analysis. Neurons were treated with lithium and CHIR-99021, a selective inhibitor of the lithium target GSK3B, as well as an inhibitor of CRMP2, an axon-specific substrate of GSK3B. Results RNAseq identified 283 differentially expressed genes between Ank3+/- and Ank3+/+ mouse hippocampus (fold change>1.2, p 20% increased EB3, p 30%, p Discussion Ankyrin3 disruption in mice is associated with altered neuronal microtubule dynamics. Lithium reversal of both the microtubule and behavioral changes of Ank3+/- mice suggest that microtubule defects underlie manic-like behaviors observed in these mice. Our results support the investigation of risk genes using mouse and neuronal models to elucidate the neural mechanisms underlying psychiatric illness.

Experimental evaluation of wall shear stress in a double contraction nozzle using a water mock-up of a liquid Li target for an intense fusion neutron source

Herein, the wall shear stress in a double contraction nozzle has been evaluated experimentally to produce a liquid lithium (Li) target as a beam target for intense fusion neutron sources such as the International Fusion Materials Irradiation Facility (IFMIF), the Advanced Fusion Neutron Source (A-FNS), and the DEMO Oriented Neutron Source (DONES). The boundary layer thickness and wall shear stress are essential physical parameters to understand erosion–corrosion by the high-speed liquid Li flow in the nozzle, which is the key component in producing a stable Li target. Therefore, these parameters were experimentally evaluated using an acrylic mock-up of the target assembly. The velocity distribution in the nozzle was measured by a laser-doppler velocimeter and the momentum thickness along the nozzle wall was calculated using an empirical prediction method. The resulting momentum thickness was used to estimate the variation of the wall shear stress along the nozzle wall. Consequently, the wall shear stress was at the maximum in the second convergent section in front of the nozzle exit.

A study of the simulation of the influence on formed neutron spectrum when Li target was covered with polyimide protective film

7Li(p,n)7Be reaction can be used for neutron generation for use in BNCT, but the lithium target must be protected from exposure to air, typically by being kept in vacuum. Keeping lithium target in vacuum and isolated conditions in all stages of construction and replacement in the system can be difficult and expensive. In this article we propose a method to prevent lithium’s reactivity with air using proper materials. The results show that use of polyimide, is a good choice for preventing lithium’s reactivity with air, and it is also a cost-effective choice. In addition, this choice has many benefits among them the reduction of fast neutron flux to 41% and it also establishes the IAEA-recommended in-air parameters. Dosimetric evaluation in the simulated head phantom shows that our designed beam is useful to treat deep seated brain tumors with the reduction of damage to the healthy tissue when treating deep-seated brain tumors. The dose in the first point in healthy tissue will decreases about 17%. All calculations were performed with the MCNPX code.

The design and thermo-structural analysis of target assembly for high intensity neutron source

The engineering design of an integrated target assembly of IFMIF lithium target was performed in IFMIF/EVEDA project for a high intensity neutron source. In the evaluation of the design, a thermos-structural analysis of was evaluated by ABAQUS code, and the modeling region was a part of the target assembly which was from the inlet nozzle to the outlet pipe. The material of the target assembly including the back plate was F82H steel. In the thermal-structural analysis, the normal operations and start/stop or abnormal operations were evaluated at 250 or 300 °C operation of Li flow in inlet pipe. The result showed that the temperature of the target assembly was evaluated to be still lower than the Li boiling point of 344 °C under a vacuum pressure of 10−3 Pa. In a temperature constant operation, the calculated stresses and displacements were small enough for thermal soundness of the target assembly in steady states. In a transient cooling process from 300 °C to 20 °C through 250 °C, the maximum Mises stress was found to be 372 MPa, which was lower than the yield stress at 300 °C.

An assessment of the available alternatives for fusion relevant neutron sources

The discovery of void swelling in neutron-irradiated stainless steels by Cawthorne and Fulton in 1966 showed that radiation effects would seriously affect the lifetime of fission reactors. A few years later, in the early 1970s, serious damage levels were observed in core components of the first commercial fission reactors that had been in operation for one decade. Driven by the harder neutron spectrum, the fusion community was impelled to explore the technical possibilities to make available a fusion relevant neutron source to anticipate the difficulties faced by the fission reactors community and ensure the long-term operation of a fusion reactor. In 1976, the conclusions of the first review published announced the assets and drawbacks of the different possibilities, which today despite the four decades passed and the sound technological advancements, continue being basically the same. A suitable neutron spectrum can be theoretically obtained both from plasma-based or accelerators based facilities with either gas, liquid or solids targets. Needed facilities performances, available irradiation volumes that the concept allow and cost are at stake. In the past, the cost of the most promising facility based on stripping the neutron from a deuteron on a lithium target was misleadingly peered with that of a fusion reactor. A tokamak with sufficient volume to irradiate equipment under fusion relevant conditions will be likely available in the future once commercial fusion reactors have become a reality; unfortunately, this concept does not match the needs timely, and is unrealistic w.r.t. its costs nowadays with worldwide efforts prioritizing ITER. In this article, we will focus on the technical aspects and assess the present maturity of different existing possibilities based on nowadays technologies to count with neutrons at a suitable flux and spectrum to characterize and qualify fusion materials to be timely ready with our world fusion roadmaps.