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This article is a short summary of the talk presented at 2014 Instrumentation Conference in Novosibirsk about Fermilab's experimental program and future plans. It includes brief description of the P5 long term planning progressing in US as well as discussion of the future accelerators considered at Fermilab.
The high-brightness beams being produced in current and future accelerators present new machine protection concerns with the potential for high-energy-density (HED) conditions ( >100 J/mm 3 ) in beam-intercepting components. Simulating HED conditions in accelerators requires utilizing a suite of physics codes for particle dynamics, particle-matter interactions, and hydrodynamics. This paper describes a method of coupling the codes elegant, fluka, and flash to simulate the effects of a rapid beam loss in the advanced photon source storage ring and the resulting interaction of the beam and collimators. This paper expands previous work [J. Dooling et al., Collimator irradiation studies at the advanced photon source, in Proceedings of the IBIC-2023 (2023), pp. 245–249] by introducing a definition of the evolving geometry of the collimator surface as well as providing methods for simulating the absorption of synchrotron radiation and tracking shower particles produced during beam strikes. We demonstrate this framework by simulating machine conditions of the APS ring before and after its recent upgrade. Simulation results are compared with observed damage to collimators and test samples taken from the APS ring.
A terrestrial population of room-temperature millicharged particles can arise if they make up a dark matter subcomponent or if they are light enough to be produced in cosmic ray air showers. In a companion paper, we showed that a simple electrified shell acts as an efficient accumulator for such particles, parametrically enhancing their local density by many orders of magnitude. Here we demonstrate that Cavendish tests of Coulomb’s Law, performed since the late 18th century, function as both quasistatic accumulators and detectors for this overdensity. Reinterpretations of these past Cavendish tests thus provide some of the strongest bounds on a terrestrial millicharge population. We also propose surrounding a Cavendish test with an additional charged shell, which significantly improves the sensitivity and can even enable detection of the irreducible density of millicharged particles generated from cosmic rays. Using decades-old technology, this can outperform future accelerator searches for sub-GeV masses.
A terrestrial population of millicharged particles that interact significantly with normal matter can arise if they make up a dark matter subcomponent or if they are light enough to be produced in cosmic-ray air showers. Such particles thermalize to terrestrial temperatures through repeated scatters with normal matter in Earth’s environment. We show that a simple electrified shell (for example, a Van de Graaff generator) functions as an efficient accumulator of such room-temperature millicharged particles, parametrically enhancing their local density by as much as 12 orders of magnitude. This can be used to boost the sensitivity of any detector housed in the shell’s interior, such as ion traps and tests of Coulomb’s law. In a companion paper, we apply this specifically to Cavendish tests of Coulomb’s law, and we show that a well-established setup can probe a large region of unexplored parameter space, with sensitivity to the irreducible density of millicharged particles generated from cosmic rays that outperforms future accelerator searches for sub-GeV masses.
Neutrino-nucleus cross section uncertainties are expected to be a dominant systematic in future accelerator neutrino experiments. The cross sections are determined by the linear response of the nucleus to the weak interactions of the neutrino, and are dominated by energy and distance scales of the order of the separation between nucleons in the nucleus. These response functions are potentially an important early physics application of quantum computers. Here we present an analysis of the resources required and their expected scaling for scattering cross section calculations. The current estimates of Trotter steps needed to achieve an energy resolution of 10 MeV and the number of CNOT gates for analyzing Ar40 highlights the need for significant improvements in algorithms. We also examine simple small-scale neutrino-nucleus models on modern quantum hardware. In this paper, we use variational methods to obtain the ground state of a three nucleon system (the triton) and then implement the relevant time evolution. To tame the errors in present-day NISQ devices, we explore the use of different error-mitigation techniques to increase the fidelity of the calculations.
We study the contributions of colorless vectorlike fermions to the triple gauge couplings W+W-γ and W+W-Z0. We consider models in which their coupling to the Standard Model Higgs boson is allowed or forbidden by quantum numbers. We assess the sensitivity of the future accelerators FCC-ee, ILC, and CLIC to the parameters of these models, assuming they will be able to constrain the anomalous triple gauge couplings with precision δκV∼O(10-4), V=γ,Z0. We show that the combination of measurements at different center-of-mass energies helps to improve the sensitivity to the contribution of vectorlike fermions, in particular when they couple to the Higgs. In fact, the measurements at the FCC-ee and, especially, the ILC and the CLIC, may turn the triple gauge couplings into a new set of precision parameters able to constrain the models better than the oblique parameters or the H→γγ decay, even assuming the considerable improvement of the latter measurements achievable at the new machines.
Recently, a Cambrian explosion of novel, non-volatile memory (NVM) devices known as memristive devices have inspired effort in building hardware neural networks that learn like the brain. Early experimental prototypes built simple perceptrons from nanosynapses, and recently, fully-connected multi-layer perceptron (MLP) learning systems have been realized. However, while backpropagating learning systems pair well with high-precision computer memories and achieve state-of-the-art performances, this typically comes with a massive energy budget. For future Internet of Things/peripheral use cases, system energy footprint will be a major constraint, and emerging NVM devices may fill the gap by sacrificing high bit precision for lower energy. In this work, we contrast the well known MLP approach with the Extreme Learning Machine (ELM) or NoProp approach, which uses a large layer of random weights to improve the separability of high-dimensional tasks, and is usually considered inferior in a software context. However, we find that when taking device non-linearity into account, NoProp manages to equal hardware MLP system in terms of accuracy. While also using a sign-based adaptation of the delta rule for energy-savings, we find that NoProp can learn effectively with four to six ’bits’ of device analog capacity, while MLP requires eight bit capacity with the same rule. This may allow the requirements for memristive devices to be relaxed in the context of online learning. By comparing the energy footprint of these systems for several candidate nanosynapses, as well as realistic peripherals, we confirm that memristive NoProp systems save energy compared to MLP systems. Lastly, we show that ELM/NoProp systems can achieve better generalization abilities than nanosynaptic MLP systems when paired with pre-processing layers (which do not require backpropagated error). Collectively, these advantages make such systems worthy of consideration in future accelerators or embedded hardware.
Atomic layer deposition (ALD) is a versatile technique for engineering the surfaces of porous polymers, imbuing the flexible, high-surface-area substrates with inorganic and hybrid material properties. Previously reported enhancements include fouling resistance, electrical conductance, thermal stability, photocatalytic activity, hydrophilicity, and oleophilicity. However, there are many poorly understood phenomena that introduce challenges in applying ALD to porous polymers. In this paper, we address five common challenges and ways to overcome them: (1) entrapped precursor, (2) embrittlement, (3) film fracture, (4) deformation, and (5) pore collapse. These challenges are often interrelated and can exacerbate one another. To investigate these phenomena, we applied various ALD chemistries to porous polymers including polyethersulfone, polysulfone, polyvinylidene fluoride, and polycarbonate track-etched membranes. Reaction-diffusion modeling revealed why certain precursors and processing conditions result in embrittling subsurface material growth, entrapment of unreacted precursors, and nongrowth. We quantify the limits of ALD processing temperatures that are dictated by thermal expansion mismatch and can lead to fractured ALD films. The results herein allow us to make recommendations to avoid, mitigate, or overcome the difficulties encountered when performing ALD and plasma-enhanced ALD on porous polymers. We intend this article to serve as a “lessons learned” guide informed by previous experience to provide a better understanding of the difficulties and limitations of ALD on porous polymers and knowledge-based guidelines for successful depositions. This knowledge can accelerate future research and help experimentalists navigate and troubleshoot as they expose porous polymers to reactive precursor vapors.
The quality of an electromagnetic pulse weld is strongly affected by a variety of interacting physical phenomena including large plastic deformation, materials mixing, localised heating and rapid cooling, and possible localised melting and interfacial cracks and void. In the present study, a thermomechanically coupled dynamic model has been developed to quantitatively resolve the high speed impact joining interface characteristics as well as the process induced interface temperature evolution, defect formation and possible microstructural composition variations. Reasonably good agreement has been obtained between the predicted results and the experimental measurements in terms of interfacial morphology characteristics. The modelling framework is expected to provide further understanding of the hierarchical interfacial features of the non-equilibrium material joining process and the weld formation mechanisms.
Abstract Lead halide perovskites have emerged as a new class of semiconductor materials with exceptional optoelectronic properties, sparking significant research interest in photovoltaics and light-emitting diodes. However, achieving long-term operational stability remains a critical hurdle. The soft, ionic nature of the halide perovskite lattice renders them vulnerable to various instabilities. These instabilities can be triggered by factors such as photoexcitation, electrical bias, and the surrounding electrolyte/solvent or atmosphere under operating conditions. Spectroelectrochemistry offers a powerful approach to bridge the gap between electrochemistry and photochemistry (or spectroscopy), by providing a comprehensive understanding of the band structure and excited-state dynamics of halide perovskites. This review summarizes recent advances that highlight the fundamental principles, the electronic band structure of halide perovskite materials, and the photoelectrochemical phenomena observed upon photo- and electro-chemical charge injections. Further, we discuss halide instability, encompassing halide oxidation, vacancy formation, ion migration, degradation, and sequential expulsion under electrical bias. Spectroelectrochemical studies that provide a deeper understanding of interfacial processes and halide mobility can pave the way for the design of more robust perovskites, accelerating future research and development efforts. Graphical Abstract
The oleaginous yeast Rhodosporidium toruloides is considered a promising candidate for production of chemicals and biofuels thanks to its ability to grow on lignocellulosic biomass, and its high production of lipids and carotenoids. However, efforts to engineer this organism are hindered by a lack of suitable genetic tools. Here we report the development of a CRISPR/Cas9 system for genome editing in R. toruloides based on a fusion 5S rRNA–tRNA promoter for guide RNA (gRNA) expression, capable of greater than 95% gene knockout for various genetic targets. Additionally, multiplexed double‐gene knockout mutants were obtained using this method with an efficiency of 78%. This tool can be used to accelerate future metabolic engineering work in this yeast.
A cloud of very fast, O (km/s), and very fine, O (µm), particles may be ejected when a strong shock impacts and possibly melts the free surface of a solid metal. To quantify these dynamics, this work develops an ultraviolet, long-working distance, two-pulse Digital Holographic Microscopy (DHM) configuration and is the first to replace film recording with digital sensors for this challenging application. A proposed multi-iteration DHM processing algorithm is demonstrated for automated measures of the sizes, velocities, and three-dimensional positions of non-spherical particles. Ejecta as small as 2 µm diameter are successfully tracked, while uncertainty simulations indicate that particle size distributions are accurately quantified for diameters ≥4 µm. These techniques are demonstrated on three explosively driven experiments. Measured ejecta size and velocity statistics are shown to be consistent with prior film-based recording, while also revealing spatial variations in velocities and 3D positions that have yet to be widely investigated. Having eliminated time-consuming analog film processing, the methodologies proposed here are expected to significantly accelerate future experimental investigation of ejecta physics.
High gradient superconducting cavities (SRF) will be needed for future accelerators. The higher gradient can achieve the high energy with fewer cavities. However the accelerating field of niobium cavities is limited by the peak magnetic field on the cavity surface. Cavities coated with Nb3Sn have a significantly larger Hc2 allowing the cavity to achieve a larger gradient. Measurements of Nb3Sn coated cavities have achieved about half the theoretical predicted gradient. It is possible to improve Nb3Sn plated cavity performance.
The nitrogen-doped cavities used in the Linac Coherent Light Source II (LCLS-II) cryomodules have shown an unprecedented high Q₀ in vertical and cryomodule testing compared with cavities prepared with standard methods. While demonstration of high Q₀ in the test stand has been achieved, maintaining that performance in the linac is critical to the success of LCLS-II and future accelerator projects. The LCLS-II cryomodules required a novel method of measuring Q₀, due to hardware incompatibilities with existing procedures. Initially developed at Jefferson Lab during cryomodule acceptance testing before being used in the tunnel at SLAC, we use helium liquid level data to estimate the heat generated by cavities. We first establish the relationship between the rate of helium evaporation from known heat loads using electric heaters, and then use that relationship to determine heat from an RF load. Here we present the full procedure along with the development process, lessons learned, and reproducibility while demonstrating for the first time that world record Q₀ can be maintained within the real accelerator environment.
Superconducting coils wound with HTS conductor can be used in magnets located in a high radiation environment. NbTi and Nb 3 Sn superconductors must operate at 4.5 K or below where removal of heat is less efficient. The HTS conductor can carry significant current at higher temperatures where the Carnot efficiency is significantly more favorable and where the coolant heat capacity is much larger. Using the HTS conductor the magnet can be operated at 40 K. This project examines the use of HTS conductor for the Michigan State University Facility For Rare Isotope Beams (FRIB) fragment separator dipole magnet which bends the beam by 30° and is located in a high radiation region that will not be easily accessible. Two of these magnets are needed to select the chosen isotope. There are a number of technical challenges to be addressed in the design of this magnet. The separator dipole is 2 m long and subtends a large angle. The magnet should keep a constant transverse field profile along its beam reference path. Winding coils with a curved inner segment is difficult as the conductor will tend to unwind during the process. In the Phase I project two approaches to winding the conductor were examined. The first was to wind the coils with curved sections on the inner and outer segments with the inner segment wound with negative curvature. The alternate approach was to use a straight segment on the inner segment to avoid negative curvature. In Phase I coils with a limited number of turns were successfully wound and tested at 77 K for both coil configurations. The Phase II program concentrated on the design, coil winding procedures, structural analysis, prototyping and testing of an HTS curved dipole coil at 40 K with a heat load representative of the radiation environment. One of the key criteria of the design of this magnet is to avoid the use of organic materials that would degrade rapidly in radiation. The Lorentz forces expected from the coils interacting with the magnetic field are large and in order minimize the deformation of the coils, mechanical support must be provided. Since the support structure cannot be made of organic materials with minimal thermal conductivity, an optimization was explored comparing the amount of coil deformation that can be tolerated and the amount of heat leakage that can be endured. A test coil containing 500 m of HTS was constructed to be tested at the 40 K operating temperature. The anticipated heat load was simulated with heater strips to demonstrate that the heat could be removed and that the coil can operate in a stable state. The FRIB project has decided that using HTS coils for this magnet was too risky considering their time and funding constraints and has opted for a more conservative approach with conventional coils. As an outcome of this STTR project, it is likely that HTS coils operating at higher temperatures will have beneficial applications for future accelerator projects.
The International Committee for Future Accelerators (ICFA) set up the Global Design Effort (GDE) for the design of the International Linear Collider (ILC) in 2005. Drawing on the resources of over 300 national laboratories, universities and institutes worldwide, the GDE produced a Reference Design Report in 2007, followed by a more detailed Technical Design Report (TDR) in 2013. Following this report, the GDE was disbanded. A compact core team, the Linear Collider Collaboration (LCC), replaced it. This is still under the auspices of ICFA and is directly overseen by the Linear Collider Board, which reports to ICFA. The LCC is charged with continuing the design effort on a much-reduced scale until the Project is approved for construction. An additional mandate of the LCC was to bring together all linear collider work, including the CERN-based Compact Linear Collider (CLIC) under one structure in order to exploit synergies between the two studies.
Ideally Mechanical center coincides with magnetic center for a perfectly manufactured magnet. However, this is not the case in a real world. This requires magnet should be magnetically fiducialized and aligned to reduce the error that caused by this kind of discrepancy. A high-precision and costly vibrating wire system is used in NSLS-II project to align all the magnets in one common girder magnetically with a precision better than ±10 micron. It can be deemed as a ruler to gauge the magnetic and mechanical center deviation for NSLS-II magnets. This information will be useful for future accelerator regarding alignment technique selection.
The International Linear Collider (ILC) is a next-generation experimental facility to explore fundamental laws of the Universe. The importance of electron-positron linear colliders as a future experimental facility has been long recognized by the worldwide high energy physics community. A global design team, the Global Design Efforts (GDE), was set up under the International Committee for Future Accelerators (ICFA) for design and coordination of R&D activities of the ILC in 2005, and the ILC Technical Design Report (TDR) was completed in 2013. ICFA then established the Linear Collider Collaboration (LCC) and the Linear Collider Board (LCB) and has continued to support the worldwide efforts for realizing the ILC. Meanwhile, in 2012, KEK and the high energy physics community in Japan proposed that Japan should host the ILC, which was welcomed by the worldwide high energy physics community. Implementation of the ILC project will require strong involvements from international partners due to its scientific importance and large scale. Aspects of international cost sharing and governance of the organization carrying out the ILC project will need to be discussed and agreed at the governmental level. Therefore, KEK established an International Working Group (WG) on the ILC Project in May 2019, inviting scientific experts worldwide* , and asking them to study international aspects of the project implementation from viewpoints of researchers. They were requested to create a report on model of international cost sharing for construction and operation, organization and governance of the ILC Laboratory, and international sharing of the remaining technical preparation. The WG report was submitted to KEK on September 25, 2019. After reviewing the content of the report, KEK decided to make it available within this document entitled “Recommendations on ILC Project Implementation”. This document summarizes the deliberations from researchers’ viewpoints; it does not intend to pre-empt governments and funding agencies. It is hoped that it will be helpful for discussions among governments and funding agencies.