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At least 541 records · Page 30

Ultrafast electron diffraction: Visualizing dynamic states of matter

Since the discovery of electron-wave duality, electron scattering instrumentation has developed into a powerful array of techniques for revealing the atomic structure of matter. Beyond detecting local lattice variations in equilibrium structures with the highest possible spatial resolution, recent research efforts have been directed toward the long-sought-after dream of visualizing the dynamic evolution of matter in real time. The atomic behavior at ultrafast timescales carries critical information on phase transition and chemical reaction dynamics, the coupling of electronic and nuclear degrees of freedom in materials and molecules, and the correlation among structure, function, and previously hidden metastable or nonequilibrium states of matter. Ultrafast electron pulses play an essential role in this scientific endeavor, and their generation has been facilitated by rapid technical advances in both ultrafast laser and particle accelerator technologies. Here this review presents a summary of the noteworthy developments in this field in the last few decades. The physics and technology of ultrafast electron beams is presented with an emphasis on the figures of merit most relevant for ultrafast electron diffraction experiments. Recent developments in the generation, manipulation, and characterization of ultrashort electron beams aimed at improving the combined spatiotemporal resolution of these measurements are discussed. The fundamentals of electron scattering from atomic matter and the theoretical frameworks for retrieving dynamic structural information from solid-state and gas-phase samples is described. Essential experimental techniques and several landmark works that have applied these approaches are also highlighted to demonstrate the widening applicability of these methods. Ultrafast electron probes with ever-improving capabilities, combined with other complementary photon-based or spectroscopic approaches, hold tremendous potential for revolutionizing our ability to observe and understand energy and matter at atomic scales.

43 PARTICLE ACCELERATORS↗

Selecting 1D projections for 2D tomography reconstruction

Previous works on reconstructing the 4D phase space using tomography require optimal selection of projection views to achieve accurate reconstruction. In 2D reconstruction, the process is straightforward, as an object can be evenly sampled by dividing the angles evenly. However, extending this concept from 2D to 4D is not intuitive. This work demonstrates that quaternions can be used to more effectively describe views in 4D and introduces the Fibonacci Flower algorithm and repulsive force algorithm to evenly space views in 4D space in order to achieve higher reconstruction accuracy.

Accelerator Physics↗

eLog analysis for accelerators: status and future outlook

This work demonstrates electronic logbook (eLog) systems leveraging modern AI-driven information retrieval capabilities at the accelerator facilities of Fermilab, Jefferson Lab, Lawrence Berkeley National Laboratory (LBNL), SLAC National Accelerator Laboratory. We evaluate contemporary tools and methodologies for information retrieval with Retrieval Augmented Generation (RAGs), focusing on operational insights and integration with existing accelerator control systems. The study addresses challenges and proposes solutions for state-of-the-art eLog analysis through practical implementations, demonstrating applications and limitations. We present a framework for enhancing accelerator facility operations through improved information accessibility and knowledge management, which could potentially lead to more efficient operations.

Accelerator Physics↗

A reactive ferroelectric tuner for microphonics compensation

Jefferson Lab (JLab) is actively pursuing an extensive research program focused on developing advanced Nb₃Sn superconducting technology for particle accel-eration. Due to the brittle nature of Nb₃Sn coatings, a Ferroelectric Tuner (FRT) currently represents the most viable approach for microphonics compensation in these next-generation cavities. We suggest a novel, fast-responding FRT integrated directly into the main coupler, eliminating the need for an additional RF port. Leveraging a unique RF design based on a magic-T configuration, this advanced FRT will enable micro-phonics compensation in the ±30 Hz range without undesirable changes to the external quality factor.

Accelerator Physics↗

Lifetime extension of legacy CEBAF LLRF hardware

A significant portion of the Low-Level Radio Frequency (LLRF) hardware in Jefferson Lab’s CEBAF is from the original construction of the facility using 1980’s CAMAC technology. Of the fifty-three zones in CEBAF, thirty-six of them are legacy hardware. The age of the legacy system has led to difficulties in maintaining the hardware due to parts going obsolete without suitable drop in replacements. Continued operation of the legacy system is required as the installation of LLRF 3.0 systems is costly and cannot be completed in a short period of time with the available resources. The most pressing failure in the legacy system was a failing buffer card, which is responsible for communication between the EPICs network and individual RF control modules. A new buffer card was designed as a transparent, drop in, replacement so that upgrades are simply a matter of swapping the existing legacy hardware. This buffer card upgrades a single point failure component and promises to extend the operable lifetime of CEBAF’s legacy systems.

Accelerator Physics↗

MTA Beam Absorber

Explore the source record for details and available documents.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Light Yield Calibration in MicroBooNE

The MicroBooNE detector is a Liquid Argon Time Projection Chamber (LArTPC) located along the Booster Neutrino Beam (BNB) at Fermilab. Its primary physics goal is to contribute to addressing the elusive short-baseline MiniBooNE low energy excess. MicroBooNE records and utilises both the ionisation charge and scintillation light produced inside the TPC to select and reconstruct neutrino interactions. The scintillation light collected using a plane of PhotoMultiplier Tubes (PMTs) is also used for accurate event timing and cosmic muon rejection with the latter being an important background for detectors, such as MicroBooNE, located on the surface. A good understanding of light modeling and its related systematic uncertainties is crucial to evaluate their impact on physics analyses. The experience acquired from MicroBooNE regarding how the stability of the scintillation light behaves and evolves during the 5 years of the primary physics run will be discussed as well as the calibration method used. This experience will help with understanding the physics of scintillation light in LArTPCs for the future long-running Short-Baseline Neutrino (SBN) and Deep Underground Neutrino Experiment (DUNE) programs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Selection of charged-current neutrino-induced $K^+$ production interactions in MicroBooNE

MicroBooNE is an 85-ton active mass liquid-argon time projection chamber (LArTPC) neutrino detector exposed to the Booster Neutrino Beam (BNB) at Fermilab. MicroBooNE’s physics goals is the precision measurement of neutrino interactions on argon in the 1 GeV energy regime. The study of neutrino interactions producing a $K^+$ in the final-state can improve the background estimates for future proton-decay experiments looking for the $p → K^+$$_ν$ channel on argon such as DUNE. In this document we present a simulation study for a selection of events with a $K^+$ that is produced in a charged-current neutrino interaction and decays into a $µ^+$ and a $ν_µ$ in the MicroBooNE detector. It will focus on how we use the particle identification techniques developed by MicroBooNE to achieve a sample with a 7% efficiency and 66.7% purity. This is the first step toward a charged-current kaon production cross section measurement in argon.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Accelerator Neutrinos

Neutrino beams generated by particle accelerators are essential for probing fundamental physics. This presentation will examine the creation of high-intensity, well-collimated neutrino beams, crucial for long-baseline experiments like DUNE and NOvA. These experiments are pushing proton beam power to multi-MW levels and utilizing large-scale detectors to overcome the challenge of limited event statistics. At LBNF, the DUNE experiment will rigorously test the three-neutrino flavor model and explore CP violation by analyzing oscillation signatures in high-intensity νμ(νμˉ)νμ​(νμ​ˉ​) to νe(νeˉ)νe​(νe​ˉ​) beams. We'll explore the technical complexities of beamline components, the drive towards higher beam powers, and the strategies for measuring and managing neutrino flux. The presentation will also cover advancements in neutrino beam instrumentation and efforts to enhance beam precision, which are key to achieving the next generation of multi-megawatt accelerator facilities. By reviewing past achievements and future prospects, this talk aims to provide a clear overview of the current state and future potential of neutrino beam technology.

Ganguly, Sudeshna↗

Scattering Calorimeter FY24 Deliverable Report

A simulation-based method has been developed to prototype new detector designs for nuclear data measurements utilizing neutron scattering. This method uses representative physics inputs for signal and background generation, full detector resolution smearing benchmarked by experimental data, and a neutron beam timing simulation to produce analyzable output like a physical measurement. A test case has been studied using a hybrid time-of-flight calorimeter detector for scattering cross-section measurements on 239 Pu with 1-5 MeV incident monoenergetic neutrons. Data analysis methods have been developed to perform event-level particle reconstruction and reaction channel discrimination. This analysis has been used to estimate the capability of the test detector to perform simultaneous scattering and fission cross section measurements, as well as its ability to provide neutron spectra and particle angular information.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Baseband Digital Network Analyzer Upgrade for LLRF Controllers

Digital Network Analyzers (DNA) have been implemented in many Low-Level Radio Frequency (LLRF) systems, notably NSLS-II and CERN, to help tune feedback loops. DNA characterizes feedback loops by measuring the frequency-dependent magnitude and phase transfer functions. It enables the measurement of open loop gains, gain/phase margins, and loop delays to help fine-tune feedback loops. An FPGA-based DNA has been developed and integrated into the current Relativistic Heavy Ion Collider (RHIC) LLRF infrastructure. Its performance has been tested with an implementation of one-turn delay feedback (OTFB) on the bench to maximize gain and stability. The DNA has been used to characterize a RHIC 28 MHz cavity in a RHIC Accelerator Physics Experiment (APEX) to test transient beam loading compensation strategies.

43 PARTICLE ACCELERATORS↗

APOLLO: a facility-scale differentiable virtual accelerator for Fermilab

As the design complexity of modern accelerators grows, there is more interest in using advanced simulations that have fast execution time or yield additional insights like gradients. The FAST/IOTA facility has been working on implementing and experimentally validating an end-to-end digital twin that is both fast and gradient-aware, allowing for rapid prototyping of new software and experiments with minimal beam time costs. Our framework integrates physics and ML codes for linac and ring simulation through a set of generic interfaces between surrogate and physics-based sections. To reproduce device inputs and outputs, system state is exposed as a deterministic discrete event simulator. Because Fermilab is undergoing control system transition, both EPICS and ACNET frontends are supported. Recently, we have begun transitioning to a new community lattice standard, PALS, as well as developing standardized infrastructure for data ingest and normalization to prepare for model calibration during FAST proton injector commissioning. We discuss implementation details as well as challenges, and future plans to extend modelling to main complex proton accelerators like PIPII and Booster.

Kuklev, Nikita [Fermilab]↗

A reactive ferroelectric tuner for microphonics compensation

Jefferson Lab (JLab) is actively pursuing an extensive research program focused on developing advanced Nb₃Sn superconducting technology for particle accel-eration. Due to the brittle nature of Nb₃Sn coatings, a Ferroelectric Tuner (FRT) currently represents the most viable approach for microphonics compensation in these next-generation cavities. We suggest a novel, fast-responding FRT integrated directly into the main coupler, eliminating the need for an additional RF port. Leveraging a unique RF design based on a magic-T configuration, this advanced FRT will enable micro-phonics compensation in the ±30 Hz range without undesirable changes to the external quality factor.

Accelerator Physics↗

Elastic light-scattering modulator: A concept

Simple structure can be used as electrically-controlled light valve, to scatter both transmitted and reflected beams. Its operation is based on physical phenomenon called frosting. Device may be of interest to manufacturers of page composers, alphanumeric displays, flat-panel displays, large-screen televisions, and optical input terminals for computers.

Vilkomerson, D. H. R.↗