Overview of Linac Risk Mitigation: Life Extension Plans for the LANSCE Accelerator [Slides]
Abstract not provided.
43 PARTICLE ACCELERATORS↗
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Error Mitigation Methods in Track Reconstruction of ICARUS [Poster]
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Toroidal modeling of runaway electron loss due to 3-D fields in DIII-D and COMPASS
The 3-D field induced relativistic runaway electron (RE) loss has been simulated for DIII-D, COMPASS and ITER plasmas, utilizing the MARS-F code incorporated with the recently developed and updated RE orbit module (REORBIT). Modeling shows effectively 100% loss of a post-disruption, high-current runaway beam in DIII-D, due to the 1 kG level of magnetic field perturbation produced by a fast growing n = 1 resistive kink instability. The RE loss is shown to be independent of the particle energy or the initial location of particles in the configuration space. Applied resonant magnetic perturbation (RMP) fields from in-vessel coils are not effective for RE beam mitigation in DIII-D, but do produce finite (>10%) RE loss in COMPASS, consistent with experimental observations in above two devices. The major reasons for this difference in RE control by RMP between these two devices are (i) the coil proximity to the RE beam and (ii) the effective coil current scaling versus the machine size and the toroidal magnetic field. About 10% RE loss fraction is also predicted for an ITER 15 MA scenario with pre-disruption plasma, highlighting the role of the plasma response. Up to 30% loss is computed, however, by artificially scaling the equilibrium pressure to zero. This is due to the more resistive plasma response and stronger resulting field line stochasticity. Distributions of the lost REs to the limiting surface show poloidally peaked profile near the high-field-side in both DIII-D and COMPASS, covering about 100o poloidal angle. Higher perturbation field level and/or higher particle energy also result in REs being lost to the low-field-side of the limiting surface of these two devices, increasing the effective wetted area. Finally, for the modeled ITER plasmas, the applied RMP field, with optimal poloidal spectrum that maximizes the edge localized mode control, leads to REs being lost to the lower divertor region of the limiting surface within a narrow poloidal band.
3-D field↗
Lipkin model on a quantum computer
Atomic nuclei are important laboratories for exploring and testing new insights into the universe, such as experiments to directly detect dark matter or explore properties of neutrinos. The targets of interest are often heavy, complex nuclei that challenge our ability to reliably model them (as well as quantify the uncertainty of those models) with classical computers. Hence there is great interest in applying quantum computation to nuclear structure for these applications. As an early step in this direction, especially with regards to the uncertainties in the relevant quantum calculations, we develop circuits to implement variational quantum eigensolver (VQE) algorithms for the Lipkin-Meshkov-Glick model, which is often used in the nuclear physics community as a testbed for many-body methods. Here, we present quantum circuits for VQE for two and three particles and discuss the construction of circuits for more particles. Implementing the VQE for a two-particle system on the IBM Quantum Experience, we identify initialization and two-qubit gates as the largest sources of error. We find that error mitigation procedures reduce the errors in the results significantly, but additional quantum hardware improvements are needed for quantum calculations to be sufficiently accurate to be competitive with the best current classical methods.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Mitigating municipal solid waste fouling in biofuel conversion via screw surface modifications
Here, municipal solid waste (MSW)'s 40–60 % carbon content makes it a feedstock for biofuel production via pyrolysis. One challenge in the conversion process is MSW fouling due to thermal decomposition. The accumulated deposit on the injection screw often leads to plugging and constriction. This study examined the morphology and composition of the MSW fouling deposit and conducted a thermal simulation to understand the temperature gradience of the injection screw. Surface modifications including smoothening and anti-adhesion coating were proposed for the injection screw to address the deposit problem. For evaluating the candidate mitigations, a bench-scale fouling test was developed with the gas environment, temperature, and sliding speed relevant to the contact interface between the MSW particles and the screw. Results suggested that a smoother screw surface could reduce the grip and a non-metallic coating with a lower surface energy could decrease adhesion, consequently leading to less fouling. Specifically, reducing the roughness from 2 to 0.6 and then to 0.2 μm proportionally decreased the amount of deposit, and the diamond-like-carbon, CrN, and NiCr–CrC composite coatings effectively hindered the fouling process. This study provides fundamental insights into the MSW fouling and proof-of-concept of potential mitigations through the screw surface modification.
09 BIOMASS FUELS↗
Stochastic and a posteriori optimization to mitigate coil manufacturing errors in stellarator design
Abstract It was recently shown in Wechsung et al (2022 Proc. Natl Acad. Sci. USA 119 e2202084119) that there exist electromagnetic coils that generate magnetic fields, which are excellent approximations to quasi-symmetric fields and have very good particle confinement properties. Using a Gaussian process-based model for coil perturbations, we investigate the impact of manufacturing errors on the performance of these coils. We show that even fairly small errors result in noticeable performance degradation. While stochastic optimization yields minor improvements, it is not possible to mitigate these errors significantly. As an alternative to stochastic optimization, we then formulate a new optimization problem for computing optimal adjustments of the coil positions and currents without changing the shapes of the coil. These a-posteriori adjustments are able to reduce the impact of coil errors by an order of magnitude, providing a new perspective for dealing with manufacturing tolerances in stellarator design.
Physics↗
Investigation of Tail-dominated Instability in the Fermilab Recycler Ring
In our recent operational run, a single bunch, tail-dominated instability was observed in the Fermilab Recycler ring. This instability exclusively occurs in the vertical plane when the chromaticity is close to zero. In this study, we conduct a detailed analysis of this instability under different operational parameters. We investigate the impact of space charge on the head-tail motion and propose potential interpretations of the underlying mechanism of the instability. Moreover, we explore methods to mitigate this instability in the future.
43 PARTICLE ACCELERATORS↗
Development and Test of Simulation Tools for EIC Beam-Beam Interaction (Final Technical Report)
This final technical report summarizes the work of the Michigan State University (MSU) team supported by grant # DE-SC0018973 awarded by the Office of Nuclear Physics, Department of Energy. The awarded proposal is a joint effort of Brookhaven National Laboratory (BNL, led by Dr. Yun Luo), Lawrence Berkeley National Laboratory (LBNL, led by Dr. Ji Qiang), Thomas Jefferson National Accelerator Facility (TJNAF, led by Dr. Yves Roblin) and MSU (led by Dr. Yue Hao). The MSU personnel supported by the grant include Dr. Yue Hao and Dr. Derong Xu, who is hired as a postdoctoral research fellow. MSU team ‘s work in this proposal focused on the beam dynamics study and numerical simulation of crabbed collision with crab cavities. Analytical calculations and numerous simulations have been done to identify beam dynamics effect out of numerical noises, study the synchro-betatron resonance in the crab crossing scheme, evaluate the effects of non-ideal settings for crab cavity and the effects of the crab crossing noises. The results have been published in journals and as conference proceedings. From the results of the proposal, we gained a clear understanding of the beam-beam interaction in the EIC designs and provided robust countermeasures to possible beam-beam interaction related to beam lifetime reduction, beam emittance growth, beam instabilities, and luminosity degradation, which significantly mitigate the technical risks associated with the EIC accelerator designs.
43 PARTICLE ACCELERATORS↗
Simulation of Multipacting in SC Low Beta Cavities at FNAL
Proton Improvement Plan-II at Fermilab is a plan for improvements to the accelerator complex aimed at providing a beam power capability of at least 1 MW on target at the initiation of LBNE (Long Base Neutrino Experiment) operations. The central element of the PIP-II is a new 800 MeV superconducting linac, injecting into the existing Booster. Multipacting affects superconducting RF cavities in the entire range from high energy elliptical cavities to coaxial resonators for low-beta applications. This work is focused on multipacting study in the low-beta 325 MHz spoke cavities; namely SSR1 and SSR2, which are especially susceptible to the phenomena. The extensive simulations of multipacting in the cavities with updated material properties and comparison of the results with experimental data helped us to improve overall reliability and accuracy of these simulations. Our practical approach to the simulations is described in details. For SSR2, which has a high multipacting barrier right at the operating power level, some changes of the cavity shape to mitigate this harmful phenomenon are proposed.
43 PARTICLE ACCELERATORS↗
Coupled Bunch Instabilities Growth in the Fermilab Booster during Acceleration Cycle
Currently, Fermilab Booster accelerates ~4.5E12 protons per pulse (ppp) in 81 bunches from 400 MeV to 8 GeV at 15 Hz to provide beam to multiple HEP experiments and is being upgraded to handle higher beam intensity >6.7E12 ppp at a repetition rate of 20 Hz. In the current mode of operation, we control longitudinal coupled bunch instabilities (LCBI) using combination of passive and active dampers. The issues with LCBI are expected to worsen at higher beam intensities. Here, we would like to investigate at what time in the beam cycle a particular mode is going to originate and how much it contributes at a different time of the acceleration cycle using the collected wall current monitor data from injection to extraction. Also, measure growth rates as a function of beam intensity for some dominant modes. Finally, this paper presents results from the observed LCBI analysis for the highest available beam intensities, unexpected findings, and future plans to mitigate the LCBI at higher beam intensities
43 PARTICLE ACCELERATORS↗
Recommendation for Mitigations of the Electron Cloud Instability in the ILC
Electron cloud has been identified as one of the highest priority issues for the international Linear Collider (ILC) Damping Rings (DR). An electron cloud Working Group (WG) has evaluated the electron cloud effect and instability, and mitigation solutions for the electron cloud formation. Working group deliverables include recommendations for the baseline and alternate solutions to the electron cloud formation in various regions of the ILC Positron DR, which is presently assumed to be the 3.2 km design. Detailed studies of a range of mitigation options including coatings, clearing electrodes, grooves and novel concepts, were carried out over the previous several years by nearly 50 researchers, and the results of the studies form the basis for the recommendation. The recommendations are the result of the working group discussions held at numerous meetings and during a dedicated workshop. In addition, a number of items requiring further investigation were identified during the discussions at the Cornell meeting and studies will be carried out at CesrTA, a test accelerator dedicated to electron cloud studies, and other institutions.
43 PARTICLE ACCELERATORS↗
Fillers in cementitious materials — Experience, recent advances and future potential
The paper discusses the potential of fillers in CO{sub 2} mitigation in the cement industry. A historical overview of the use of fillers is presented as well as the limits of filler use given in cement standards. Globally, limestone filler currently represents only 7% of average worldwide cement composition. The limits of the current route to adding filler in cement by means of intergrinding are discussed. An innovative technology, that compensates binder dilution by a reduction of the water required for good rheological behavior, is presented; this allows clinker replacement rates of up to 70%. The theory that enables the design of such multimodal particle size distributions with high particle packing and low-water demand is presented, and examples of its application in concrete production are given. The efficiency in terms of CO{sub 2} mitigation is demonstrated by comparing concrete formulations designed with this innovative approach with a global benchmark of current technology. New filler minerals, as well as the effects of high-filler content on production processes and on durability are also discussed.
36 MATERIALS SCIENCE↗
Implementation of a Time-domain Cosmic-Ray-Muon Tagger for the NEXUS Low-background Cryogenic Facility
Quantifying the effects of radiation on the operation of qubits both as quantum information systems as well as particle detectors has emerged as a pressing issue in quantum science in recent years. We present an overview of the design, operation, and deployment of a 90-$\mathrm{in}^2$ three-panel muon detector for use in the NEXUS experimental facility at Fermilab to temporally isolate correlated errors in qubits and determine if they possess an astrophysical origin. Constructed with three scintillator-attached PMTs read out with NIM modules in a triply-coincident logic scheme, we measure a surface-level muon luminosity of 9.7425 muons per second---consistent with an average surface-level cosmic-ray flux of approximately one muon per square centimeter per minute. Integrating the NIM modules with an MCC 128 DAQ HAT and Raspberry Pi, a Python script records exactly when a muon struck the detector and writes a timestamp to a log file for follow-up cross referencing. This experiment will broadly contribute to further studies aimed at understanding the source and mitigation of information loss in qubits.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Transverse self-modulation of ultra-relativistic lepton beams in the plasma wakefield accelerator
The transverse self-modulation of ultra-relativistic, long lepton bunches in high-density plasmas is explored through full-scale particle-in-cell simulations. We demonstrate that long SLAC-type electron and positron bunches can become strongly radially self-modulated over centimeter distances, leading to wake excitation in the blowout regime with accelerating fields in excess of 20 GV/m. We show that particles energy variations exceeding 10 GeV can occur in meter-long plasmas. We find that the self-modulation of positively and negatively charged bunches differs when the blowout is reached. Seeding the self-modulation instability mitigates the effect of the competing hosing instability. This work reveals that a proof-of-principle experiment to test the physics of bunch self-modulation can be performed with available lepton bunches and with existing experimental apparatus and diagnostics.
43 PARTICLE ACCELERATORS↗
Feasibility of Nitrogen as a Carrier Gas for Inconel Cold Spray in Hydropower Application
Cold spray deposition of Inconel nickel alloys has emerged as a promising strategy for mitigating cavitation erosion in hydropower facilities. Most prior developments employ helium (He) as the carrier gas because it enables high particle velocities and the formation of dense coatings. However, He is nearly two orders of magnitude more expensive than nitrogen (N2), which limits its widespread adoption in the hydropower sector. Although He-based cold spray can be justified for high value repairs, the lower cost and broad availability of N2 make it an attractive alternative. This study assesses the feasibility of N2-based cold spray of Inconel 625 powders for hydropower applications. Cavitation erosion testing shows that He-based coating exhibits cavitation resistance of ~398% relative to the 304L stainless steel (SS304L) substrate. In contrast, N2-based coating shows substantially lower cavitation resistance, reaching only ~69% of the SS304L substrate, even when higher carrier gas temperature and pressure are applied. When the Inconel 625 powder size is reduced from 44 to 22 µm under N2-based cold spray conditions, cavitation resistance increases significantly to ~148% of the SS304L substrate. Additional improvement can be obtained by incorporating fine chromium carbide powders into the feedstock, resulting in cavitation resistance of ~172% of the SS304L substrate. Overall, with optimized feedstock design, N2-based cold spray offers a practical and cost-effective approach for producing cavitation resistant coatings on hydropower components, although He-based cold spray continues to deliver higher cavitation resistance.
Wang, Tianhao↗
Optimization of lithium-glass fibers with lithium depleted coating for neutron detection
Neutron-detecting scintillating glass uses 6 Li to capture thermal neutrons to produce an a and triton particle, which have $a$ range of 6 $µm$ and 36 $µm$, respectively. Captures on the surface of the glass can cause one of the particles to not deposit their energy in the glass causing the neutron to not be detected. This effect can be mitigated in lithium glass scintillators by coating lithium- glass fibers with lithium depleted scintillating glass. Thus, the scintillator’s efficiency will be increased. Results from this work show that a 20-60% increase in neutron efficiency depending on core size can be achieved with scintillating glass coatings.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Rapid biodegradation of microplastics generated from bio-based thermoplastic polyurethane
The accumulation of microplastics in various ecosystems has now been well documented and recent evidence suggests detrimental effects on various biological processes due to this pollution. Accumulation of microplastics in the natural environment is ultimately due to the chemical nature of widely used petroleum-based plastic polymers, which typically are inaccessible to biological processing. One way to mitigate this crisis is adoption of plastics that biodegrade if released into natural environments. In this work, we generated microplastic particles from a bio-based, biodegradable thermoplastic polyurethane (TPU-FC1) and demonstrated their rapid biodegradation via direct visualization and respirometry. Furthermore, we isolated multiple bacterial strains capable of using TPU-FC1 as a sole carbon source and characterized their depolymerization products. Finally, to visualize biodegradation of TPU materials as real-world products, we generated TPU-coated cotton fabric and an injection molded phone case and documented biodegradation by direct visualization and scanning electron microscopy (SEM), both of which indicated clear structural degradation of these materials and significant biofilm formation.
09 BIOMASS FUELS↗
Deep learning‑based metal artefact reduction in X-ray computed tomography of TRISO fuel compacts
TRISO (TRi-structural ISOtropic) – compact-type micro-particle fuels – are next generation nuclear fuel compacts designed with safety in mind. Structural integrity and characterisation before and after irradiation are important to determine the performance of the fuel compacts under real reactor conditions. X-ray computed tomography can be an important tool for non-destructive evaluation of these fuel compacts. The fuel particles are highly attenuating for X-rays which creates metal artefact, rendering the images unusable. Our artefact correction can mitigate these artefacts significantly. The proposed method works by first segmenting highly-attenuating structures (metal) and forward projecting to localise the source of artefacts in the projection domain, then, using a traditional or U-net-based deep learning architecture, contextually interpolating those regions to remove the artefacts. Finally the reconstruction from the modified projection is fused with the segmented metal. The proposed method shows a significant improvement in the image quality while significantly reducing the reconstruction time compared to the standard technique.
Rahman, Obaid [ORNL] (ORCID:0000000277810840)↗