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At least 991 records · Page 55

Development of the multi-purpose Cologne Compact Differential Plunger (CoCoDiff) for the measurement of nuclear level lifetimes with the Recoil Distance Doppler-shift method

Here, a new 3-foil plunger device, the Cologne Compact Differential (CoCoDiff) plunger has been built and commissioned. Due to its compact size, it can be used together with many different spectrometers and auxiliary detectors. As a commissioning experiment, level lifetimes of the $2^{+}_{1}$ and the $4^{+}_{1}$ excited states of 50 Cr have been measured, using the Differential Decay Curve method (DDCM). A derivation is given on how this method can be applied to a differential plunger measurement, in order to measure distances for lifetimes from two different regions of sensitivity at the same time. The commissioning experiment took place at the Cologne FN tandem accelerator, using the reaction 24 Mg( 32 S,4p2n) 50 Cr. Lifetimes, deduced from this measurement, agree well with literature values from earlier measurements.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Measurement of charge state distributions using a scintillation screen

Absolute cross sections measured using electromagnetic devices to separate and detect heavy recoiling ions need to be corrected for charge state fractions. Accurate prediction of charge state distributions using theoretical models is not always a possibility, especially in energy and mass regions where data is sparse. As such, it is often necessary to measure charge state fractions directly. In this paper we present a novel method of using a scintillation screen along with a CMOS camera to image the charge dispersed beam after a set of magnetic dipoles. A measurement of the charge state distribution for 88 Sr passing through a natural carbon foil is performed. Using a Bayesian model to extract statistically meaningful uncertainties from these images, we find agreement between the new method and a more traditional method using Faraday cups. Additional future work is need to better understand systematic uncertainties. Our technique offers a viable method to measure charge state distributions.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Design, construction, and performance of the GEM based radial time projection chamber for the BONuS12 experiment with CLAS12

Here, a new radial time projection chamber based on Gas Electron Multiplier amplification layers was developed for the BONuS12 experiment in Hall B at Jefferson Lab. This device represents a significant evolutionary development over similar devices constructed for previous experiments, including cylindrical amplification layers constructed from single continuous GEM foils with less than 1% dead area. Particular attention had been paid to producing excellent geometric uniformity of all electrodes, including the very thin metalized polyester film of the cylindrical cathode. This manuscript describes the design, construction, and performance of this new detector.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Microjet printing of metal salt or oxide targets for nuclear reaction studies on radionuclides

Radioactive targets for direct measurements of neutron-induced reactions are required to improve evaluated cross-section data and, ultimately, the fidelity of neutron reaction network simulations. Electrodeposition and molecular plating are the current state-of-the-art radioactive target production techniques, but not all metals can be electrodeposited or molecular plated with high yields. Alternative techniques can be expensive or may produce targets that are unsatisfactory in terms of thickness, yield, or purity. Microjet printing is a new, rather inexpensive technique that utilizes equipment with a small footprint and has the potential to produce thin, highly radioactive targets with good uniformity and minimal impurities from the target fabrication process. This study involved optimizing the process of producing microjet printed targets to allow for the fabrication of a stable vanadium(V) oxide (V 2 O 5 ) target that was compared with an analogous electrodeposition V 2 O 5 target manufactured via the application of a vanadium chemical conversion coating on aluminum (Al) foil. Finally, the results from these studies suggest microjet printing could be used to produce relatively uniform target layers with adequate film thicknesses (< 15 μm). V 2 O 5 microjet printed targets, when compared with chemical conversion coating V 2 O 5 targets, appeared to be qualitatively less uniform and quantitatively larger in thickness (11.7(27) μm vs. 5.3(18) μm). However, the conversion coating target contained more impurities and the Al backing had a higher background contribution to measurements of neutron-induced reactions as opposed to targets produced via microjet printing. Overall, the results from this study suggest microjet printing has the capability to be an excellent alternative target production technique to the electrodeposition and molecular plating methods.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Generation of a controllable TNSA deuteron beam using deuterated metal targets

This study investigated the feasibility of using deuterated titanium targets for the generation of a target normal sheath acceleration (TNSA) deuteron beam. Commercial 25-μm-thick titanium foil was cut into 500 x 500-μm 2 squares and subsequently deuterated using different approaches. The spectra and total yields of all emitted ions were measured using a Thomson parabola ion spectrometer. It was found that a 24-h exposure to 1 atm of D 2 gas at 400°C is the most-efficient deuteration method, producing yields in the mid-10 11 deuterons per shot. The deuteron energy spectra changed from an exponential shape at low ion yields to exponentially modified Gaussians at higher yields. Simulations suggest that this effect is due to increased Coulomb interactions between the ions, which suppress the low energies. Separate campaigns will utilize the presented approach to produce a TNSA triton beam. Furthermore, two such targets will be used in a pitcher/catcher configuration to study the tritium–tritium reaction T(t, 2n)α.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

10 Be at iThemba LABS using a silicon nitride membrane stack as absorber for isobar suppression

10 Be is an important isotope for accelerator mass spectrometry (AMS) because of the demand for cosmogenic radionuclide dating methods in the earth science and paleo-sciences community. At the iThemba Laboratory for Accelerator Based Science (iThemba LABS) we implemented full suppression of the interfering isobar 10 B using a silicon nitride foil-stack, utilizing the 2+ charge state for high efficiency. We demonstrate the performance of this newly established AMS system using standards and test samples. Here we further present the results of an inter-comparison between iThemba LABS and the Center for Accelerator Mass Spectrometry/Lawrence Livermore National Laboratory, on AMS samples prepared from purified quartz at the University of Vermont. The results for 10 Be from the laboratories are in close agreement, fully consistent with cross-calibration between them. AMS results for 26 Al are in similarly good agreement, demonstrating the performance and accuracy of iThemba LABS for the most commonly measured in situ produced cosmogenic nuclides.

10-Be↗

Determination of the nat Ti(d,x) 49 V excitation function by liquid scintillation analysis

Here, the experimental cross-sections for deuteron-induced nuclear reactions on natural titanium were measured using the stacked-foil method. Deuteron beams were provided by a Pelletron tandem accelerator at incident energies up to 8 MeV. The cross-sections for the production of 49 V were determined by liquid scintillation analysis, with the highest measured value of 522(32) mb occurring at 5.59(9) MeV. Additionally, the cross-sections for the production of 44m,46,47,48 Sc and 48 V were evaluated using gamma-ray spectroscopy and compared to some available literature.

43 PARTICLE ACCELERATORS↗

Characterizing secondary neutrons at BLIP for isotope production applications

Fast secondary neutrons created at the Brookhaven Linac Isotope Producer (BLIP) facility following proton irradiation were characterized by the foil activation technique and compared with FLUKA Monte Carlo simulations. The FLUKA-simulated neutron flux was spectrally adjusted following the maximum entropy formalism using the International Reactor Dosimetry and Fusion File (IRDFF-II), with predictions agreeing with experimental measurements to within 9 % following the adjustment procedure. Here, a multitude of degrader configurations were simulated to assess the feasibility of improving the fast (E n > 20 MeV) secondary neutron yield at the proposed neutron target position (“N-slot”). A configuration where the N-slot is closest to the proton degrader produced the highest fast neutron yield, with tungsten degraders achieving the best performance. Assuming the optimized target-degrader configuration proposed in this work, we discuss potential isotope production opportunities with secondary neutrons. In most cases the yields are in the order of several mCi.

07 ISOTOPE AND RADIATION SOURCES↗

Development of a thermal creep model for aluminum alloy 6061 cladding in U-10Mo monolithic fuel plates

Plate-type fuel elements consisting of a high-density, low-enriched uranium (LEU) U–10Mo-based fuel foil encapsulated in an aluminum alloy (AA) cladding are fabricated using the hot isostatic pressing (HIP) technique. During the HIP process, the fuel plate system is heated to 560 °C, then cooled to room temperature. This heat cycle significantly affects the mechanical properties of the aluminum cladding, and experimental investigations have shown that, post-HIP bonding, the mechanical properties of the aluminum cladding transition from those of AA 6061-T6 to something closer to the O temper. More specifically, the ultimate strength of the cladding decreases while its ductility increases, making it challenging to capture the changes in mechanical behavior and material properties. Understanding the residual stresses generated during the HIP process is critical for assessing the fuel plate’s integrity under various temperature, pressure, and irradiation. To simulate the HIP bonding process, the elastic, plastic, and thermal properties of the cladding are assumed to be similar to those of AA 6061-O temper. However, the primary challenge lies in the lack of available data for the creep model of the AA 6061 cladding during this transient process of HIP. The present study focuses on developing a computational model that predicts the creep behavior of the aluminum cladding in the fuel plates during the HIP process, as cladding creep significantly influences the residual stresses generated in U-10Mo fuel plates during HIP fabrication. Furthermore, as HIP bonding occurs at high temperatures that are nearing the melting point of aluminum, the present work considered a temperature-dependent Arrhenius-type creep model. In particular, a hyperbolic sine creep model is employed to estimate the creep properties of the as-fabricated aluminum cladding. In conclusion, the residual stresses predicted in the U-10Mo fuel when using the newly calibrated creep model closely align with the experimental measurements, validating the model’s accuracy.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Excitation function of 54 Fe(p, α ) 51 Mn from 9.5 MeV to 18 MeV

Excitation function of the 54 Fe(p,α) 51 Mn reaction was measured from 9.5 to 18 MeV $E_{0,p^+}$ by activating a foil stack of 54 Fe electrodeposited on copper substrates. Residual radionuclides were quantified by HPGe gamma ray spectrometry. Both 51 Mn ($t_{1/2}$ = 46.2 min, $\langle E_{β^+}\rangle$=963.7keV, $I_{β^+}$ = 97%; $E_γ$ = 749.1keV, $I_γ$ = 0.265%) and its radioactive daughter, 51 Cr ($t_{1/2}$ = 27.704d, $E_γ$ = 320.1 keV, $I_γ$ = 9.91%), were used to indirectly quantify formation of 51 Mn. Results agree within uncertainty to the only other measurement in literature and predictions of default TALYS theoretical code. Final relative uncertainties are within ±12%.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

An electrochemical generator for the continual supply of 213 Bi from 225 Ac for use in targeted alpha therapy applications

Bismuth-213 is a radionuclide of interest for targeted alpha therapy and is supplied via a radiochemical generator system through the decay of 225 Ac. Radionuclide generators employ longer lived “parent” radionuclides to routinely supply shorter-lived “daughter” radionuclides. The traditional 225 Ac/ 213 Bi radiochemical generator relies on an organic cation exchange resin where 225 Ac binds to the resin and 213 Bi is routinely eluted. These resins degrade when they absorb large doses of ionizing radiation (>1 × 10 6 Gy/mg), which has been observed when the loading activity of 225 Ac exceeds 2.59*10 9 Bq (70 mCi). Herein we report the development of an electrochemical generator for the supply of 213Bi that has the potential to overcome this limitation. Bismuth-213 spontaneously electrodeposits onto nickel foils in 0.1 M hydrochloric acid at 70 °C. Using this method, we were able to plate an average of 73 ± 4 % of the 213 Bi in solution and obtain a final 213 Bi recovery of 65 ± 8 % in 0.1 M citrate pH 4.5 via reverse electrolysis using titanium as the cathode. The recovered 213Bi had an average radiochemical purity of >99.8 % and was successfully used to radiolabel DOTATATE with an average radiochemical yield of 85.1 % (not optimized).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Hybrid model to evaluate the frequency-dependent leakage inductance of partially-filled transformers

The leakage inductance of a transformer designed for a power electronic converter can drop significantly as the switching frequency is increased due to skin and proximity effects. Although the magnetic image method-based double-2-D model can predict the low-frequency leakage inductance of a partially-filled transformer with sufficient accuracy, it is inherently a frequency-independent model. While Dowell’s 1-D model uses frequency-dependent relations to account for both skin and proximity effects, its accuracy is severely affected by the assumed winding geometry. In this paper, a semianalytical hybrid model is proposed that uses superposition to combine a modified Dowell’s model with the double-2-D model to predict the true leakage inductance of partially-filled transformers at any given frequency. All three conductor types—round, foil, and litz wire—are modeled and analyzed. The quasi-2-D model is further investigated on a variable inductance transformer (VIT) whose winding geometry can be modified mechanically to vary its leakage inductance. With less than 5 % error throughout, the semi-analytically evaluated leakage inductances are in excellent agreement with the finite element method (FEM) simulated and experimentally measured leakage inductances.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Depletion benchmark for a high-assay low-enriched uranium fuel experiment in the advanced test reactor

Reactor physics depletion benchmarks for high-assay low-enriched uranium (HALEU) fuel are limited in number. In particular, there is limited data for HALEU benchmarks for U-10Mo (uranium-10% molybdenum) plate fuel that is being developed for use in the United States’ high performance research reactors including the Advanced Test Reactor (ATR), Advanced Test Reactor Critical Facility (ATR-C), High Flux Isotope Reactor (HFIR), Massachusetts Institute of Technology Reactor (MITR), University of Missouri Research Reactor (MURR), National Bureau of Standards Reactor (NBSR). These six reactors currently operate with highly enriched uranium dispersed fuel in an aluminum matrix. In support of conversion to a HALEU fuel, qualification of U-10Mo formed into a monolithic foil is being performed. Fuel qualification involves irradiating fuel specimens in the ATR. The irradiation tests provide an opportunity to benchmark depletion capabilities of reactor physics codes in support of the ATR operation, as well as develop benchmarks that can be used by other institutions to benchmark other reactor physics codes. This paper documents the development of a benchmark model of the irradiation of the ATR Full-size plate In center flux trap Position 7 (AFIP-7) experiment using the depletion codes MC21 and Advanced Dimensional Depletion for Engineering of Reactors (ADDER).

Nielsen, Joseph W. [Idaho National Laboratory (INL↗

Grain boundary slip transfer classification and metric selection with artificial neural networks

An artificial neural network is used to evaluate the effectiveness of six metrics and their combinations to assess whether slip transfers across grain boundaries in coarse-grained oligocrystalline Al foils. This approach extends the one- or two-dimensional projections formerly applied to analyze slip transfer. The accuracy of this binary classification reaches around 87% for the best single metric and around 90% when considering two or more metrics simultaneously. Here, the results suggest slip transfer mostly depends on the geometric relationship between grains. Training a double-layer network having 10 nodes per hidden layer with 40 measurements is sufficient to render the maximum accuracy.

36 MATERIALS SCIENCE↗

Capture of volatile RuO 4 from oxidized simulated used nuclear fuel solutions

Ruthenium is a challenging fission product in used nuclear fuel (UNF) reprocessing due to its complex redox chemistry, variable speciation in nitric acid, partial extractability, and volatility. This work presents a strategy for Ru removal based on the volatilization of RuO 4 using the strong oxidant sodium bismuthate, followed by RuO 2 deposition onto various substrates. Among the materials tested, polymer-based substrates such as polyolefin wax film (Parafilm®), exhibited superior performance, achieving up to near-quantitative Ru removal from solution. After dissolution of the substrate, 99.6% of the Ru was recovered as RuO 2 . The deposition mechanism onto the polyolefin wax film involves both physisorption and chemical reaction through oxidative cleavage of olefinic bonds within the polymer. In contrast, on inorganic substrates such as Al foil, RuO 4 undergoes incomplete surface adsorption and reduction, as confirmed by FTIR and XPS analyses. This approach remains effective under conditions of simulated oxidation of UNF solutions, selectively removing Ru while leaving other fission products in solution. As a result, capture of RuO 4 offers a practical and efficient strategy for ruthenium decontamination and recovery, offering a route for integration into existing UNF reprocessing flowsheets to enhance overall process safety and performance.

Ruthenium↗

Use of non-contact voltmeter to quantify potential induced degradation in CdTe modules

Potential induced degradation (PID) is a significant reliability issue for photovoltaic modules in the field. Conventionally, to detect the PID-affected modules, all the modules in a string are individually disconnected and measured using I-V (current–voltage) tracers. It is extremely time-consuming, expensive and unsafe (if the module connectors are field aged) approach. In our approach, we aim detecting the PID-affected modules quickly, inexpensively and safely without disconnecting individual modules in the string. In this study, contactless electrostatic voltmeter’s (ESV) strength was explored to detect the PID-affected cadmium telluride (CdTe) modules in a string. These contactless measurements on high-voltage PV strings could make this technique unique and preferable to detect PID-affected modules in a string compared to the I-V curve method. In this work, a CdTe module was stressed for PID using the Aluminum (Al) foil method in a walk-in environmental chamber, which resulted in a reduction of module's peak current (I max ), peak voltage (Vmax), and fill factor (FF), and hence power (Pmax). Outdoor light I-V, EL, and ESV measurements were performed pre- and post-PID to determine the effectiveness of the non-contact ESV technique. Further, the ESV technique successfully detected the change in V max , and hence Pmax, compared to the pre-and post-PID conditions. A difference of less than 2% was observed in the results of the non-contact and non-interruptive method compared to the conventionally used interruptive voltmeter or I-V tracer method. This technique and the test results demonstrate a significant promise to identify poor-performing modules in PV string without disconnection of individual modules in the string.

14 SOLAR ENERGY↗

The surface chemistry of cuprous oxide

The chemical and electronic properties of copper combined with its large natural abundance lend this material to impact a wide range of technological applications, including heterogeneous catalysis. The reactivity of copper in its Cu 1+ oxidation state makes this specific configuration relevant in various chemical reactions, but the facile redox properties of copper make the isolation of individual states for fundamental studies difficult. Here, in this study, we review three Cu 2 O model systems used to study the interaction of Cu 1+ with small molecules making use of surface science techniques: Cu 2 O/Cu(111), thin polycrystalline Cu 2 O films on Cu foil, and bulk Cu 2 O crystals. Advantages and disadvantages of each system are discussed and exemplified through case studies of chemical adsorption and reactivity studies.

36 MATERIALS SCIENCE↗

Versatile tape-drive target for high-repetition-rate laser-driven proton acceleration

We present the development and characterization of a high-stability, multi-material, multi-thickness tape-drive target for laser-driven acceleration at repetition rates of up to 100 Hz. The tape surface position was measured to be stable on the sub-micrometre scale, compatible with the high-numerical aperture focusing geometries required to achieve relativistic intensity interactions with the pulse energy available in current multi-Hz and near-future higher repetition-rate lasers ( > kHz). Long-term drift was characterized at 100 Hz demonstrating suitability for operation over extended periods. The target was continuously operated at up to 5 Hz in a recent experiment for 70,000 shots without intervention by the experimental team, with the exception of tape replacement, producing the largest data-set of relativistically intense laser–solid foil measurements to date. This tape drive provides robust targetry for the generation and study of high-repetition-rate ion beams using next-generation high-power laser systems, also enabling wider applications of laser-driven proton sources.

47 OTHER INSTRUMENTATION↗