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DOE OSTI2024

Recent progress in laser wire-based H- beam diagnostics at the SNS linac

Laser wire has been used for nonintrusive profile and emittance measurements of operational hydrogen ion (H-) beam at the SNS linac. In this talk, we will describe the following recent developments in the laser wire system. 1) An upgraded light source and laser transport line which enables novel measurement capabilities including longitudinal profile measurement and high-energy proton beam extraction over potentially an entire macropulse. 2) A dual-detector emittance measurement scheme that boosted the dynamic range by an order of magnitude. 3) Design and implementation laser-wire-based nonintrusive longitudinal phase space measurement system.

Liu, Yun↗

DOE OSTI2024

Fermilab Booster Beam Emittances from Quadrupole Modes Measured BPMs

The measurement of beam emittances by extracting the quadrupole mode signal from a 4 plate beam position monitor (BPM) was published at least 40 years ago. Unfortunately, in practice, this method suffers from poor signal to noise ratio and requires a lot of tuning to extract out the emittances. In this paper, an improved method where multiple BPMs are used together with better mathematical analysis is described. The BPM derived emittances are then compared with those measured by the Ion Profile Monitor (IPM). Surprisingly, the BPM measured emittances behave very well and are more realistic than those measured by the IPM.

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Fermilab Booster Beam Emittances from Quadrupole Modes Measured by BPMs

43 PARTICLE ACCELERATORS↗

DOE OSTI2020

Single shot cathode transverse momentum imaging in high brightness photoinjectors

In state of the art photoinjector electron sources, thermal emittance from photoemission dominates the final injector emittance. Therefore, low thermal emittance cathode developments and diagnostics are very important. Conventional thermal emittance measurements for the high gradient gun are time-consuming and thus thermal emittance is not measured as frequently as quantum efficiency during the lifetime of photocathodes, although both are important properties for the photoinjector optimizations. In this paper, a single shot measurement of photoemission transverse momentum, i.e., thermal emittance per rms laser spot size, is proposed for photocathode rf guns. By tuning the gun solenoid focusing, the electrons’ transverse momenta at the cathode are imaged to a downstream screen, which enables a single shot measurement of both the rms value and the detailed spectra of the photoelectrons’ transverse momenta. Both simulations and proof of principle experiments are reported.

43 PARTICLE ACCELERATORS↗

DOE OSTI2020

Studies of Beam Intensity Effects in Fermilab Booster Synchrotron. Part II: Beam Emittance Evolution

Detrimental beam dynamics effects limit performance of high intensity rapid cycling synchrotrons (RCS) such as the 8 GeV Fermilab Booster. Here we report the results of comprehensive studies of various beam intensity dependent effects in the Booster. In the previous publication we presented the dependencies of the Booster beam intensity losses on the total number of protons per pulse and on key operational parameters such as the machine tunes and chromaticities. Here we discuss two methods of the Booster beam emittance measurements (the multi-wires proportional chambers and the ionization profile monitors), analyze the intensity dependent emittance growth effects and discuss the ultimate performance of the machine now and after foreseen and proposed upgrades.

43 PARTICLE ACCELERATORS↗

DOE OSTI2020

Studies of Beam Intensity Effects in Fermilab Booster Synchrotron. Part I: Introduction, Tune and Chromaticity Scans of Beam Losses

Detrimental beam dynamics effects limit performance of high intensity rapid cycling synchrotrons (RCS) such as the 8 GeV Fermilab Booster. Here we report the results of comprehensive studies of various beam intensity dependent effects in the Booster. Part I covers the dependencies of the Booster beam intensity losses on the total number of protons per pulse and on key operational parameters such as the machine tunes and chromaticities. In Part II we cross-check two methods of the beam emittance measurements (the multi-wires proportional chambers and the ionization profile monitors), analyze the intensity dependent emittance growth effects and discuss the ultimate performance of the machine now and after foreseen and proposed upgrades.

43 PARTICLE ACCELERATORS↗

DOE OSTI2026

Measurement of the Energy Spread for CeC Project

The Coherent Electron Cooling requires small energy spread and uniformity of energy along the bunch. The diagnostics line is utilized for the measurement of the electron beam parameters. The beamline layout is shown in Fig. 1. Three quadrupoles after the linac are used to match beam into the common section. The main dipole is used to deflect beam towards common section. If it is switched off the beam goes to the diagnostics line. The beam optics in the diagnostics line is controlled by four quadrupoles. The deflecting cavity sweeping beam in the vertical direction follows the quadrupoles. Sector dipole is used for energy parameters measurement. It has deflection angle of 30 degrees. With diagnostics dipole switched off the beam propagated to the insertable slits system for emittance measurement. There are four profile monitors in the line, The first profile monitor (ACC YAG) is after the main dipole. The second profile monitor (YAG3) is in front of the diagnostics dipole after the deflecting cavity. YAG1 profile monitor is placed after the slits, and YAG2 profile monitor is placed after the diagnostics dipole. There is a solenoid between the deflecting cavity and YAG3. It is used for the beam energy measurement.

43 PARTICLE ACCELERATORS↗

DOE OSTI2021

Experimental demonstration of novel beam characterization using a polarizable X-band transverse deflection structure

The PolariX TDS (Polarizable X-Band Transverse Deflection Structure) is an innovative TDS-design operating in the X-band frequency-range. The design gives full control of the streaking plane, which can be tuned in order to characterize the projections of the beam distribution onto arbitrary transverse axes. This novel feature opens up new opportunities for detailed characterization of the electron beam. In this paper we present first measurements of the Polarix TDS at the FLASHForward beamline at DESY, including three-dimensional reconstruction of the charge-density distribution of the bunch and slice emittance measurements in both transverse directions. The experimental results open the path toward novel and more extensive beam characterization in the direction of multi-dimensional-beam-phase-space reconstruction.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Wakefield generation in hydrogen and lithium plasmas at FACET-II: Diagnostics and first beam-plasma interaction results

Plasma wakefield acceleration provides ultrahigh acceleration gradients of tens of GeV/m, providing a novel path toward efficient, compact, TeV-scale linear colliders, and high brightness free electron lasers. Critical to the success of these applications is demonstrating simultaneously high gradient acceleration, high energy transfer efficiency, and preservation of emittance, charge, and energy spread. Experiments at the FACET-II National User Facility at SLAC National Accelerator Laboratory aim to achieve all of these milestones in a single-stage plasma wakefield accelerator, providing a 10 GeV energy gain in a < 1 m plasma with high energy transfer efficiency. Such a demonstration depends critically on diagnostics able to measure emittance with mm mrad accuracy, energy spectra to determine both percent level energy spread, and broadband energy gain and loss, incoming longitudinal phase space, and matching dynamics. This paper discusses the experimental setup at FACET-II, including the incoming beam parameters from the FACET-II linac, plasma sources, and diagnostics developed to meet this challenge. Initial progress on the generation of beam ionized wakes in meter-scale hydrogen gas is discussed as well as commissioning of the plasma sources and diagnostics. Published by the American Physical Society 2024

43 PARTICLE ACCELERATORS↗

DOE OSTI2020

A compact, high resolution energy, and emittance diagnostic for electron beams using active plasma lenses

High-resolution (sub-%), single-shot energy distribution, and emittance measurements of GeV-class electron beams generated by laser plasma accelerators (LPAs) have been enabled through the use of an active plasma lens combined with relatively short dipole magnets. This setup, with only 60 cm between the LPA source and the final diagnostic screen, was facilitated through the use of a replenishable ∼20–40 nm thick liquid crystal plasma mirror to separate remnant laser radiation from the electron beam without emittance degradation. As LPAs capable of generating GeV-class electron beams at cm-scale distances become increasingly ubiquitous, there is a need to supplement these compact accelerators with equally compact diagnostics.

Barber, S. K. (ORCID:0000000172518755)↗

DOE OSTI2025

Sub-2 Kelvin Characterization of Nitrogen-Vacancy Centers in Silicon Carbide Nanopillars

The development of efficient quantum communication technologies depends on the innovation in multiple layers of its implementation, a challenge we address from the fundamental properties of the physical system at the nanoscale to the instrumentation level at the macroscale. We select a promising near-infrared quantum emitter, the nitrogen-vacancy (NV) center in 4H-SiC, and integrate it, at an ensemble level, with nanopillar structures that enhance photon collection efficiency into an objective lens. Moreover, changes in collection efficiency in pillars compared to bulk can serve as indicators of color center orientation in the lattice. To characterize NV center properties at the unprecedented sub-2 K temperatures, we incorporate compatible superconducting nanowire single photon detectors inside the chamber of an optical cryostat and create the ICECAP, the Integrated Cryogenic system for Emission, Collection And Photon detection. ICECAP measurements show no significant line-width broadening of NV ensemble emission and up to 14-fold enhancement in collected emission. With additional filtering, we measure emitter lifetimes of NV centers in a basal ( hk ) and axial ( kk ) orientation, unveiling their cryogenic values of 2.2 and 2.8 ns.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Performance evaluation of the SPES FEBIAD ion source

SPES (Selective Production of Exotic Species) is the Radioactive Ion Beam (RIB) facility that is currently in the installation phase at the Istituto Nazionale di Fisica Nucleare in the Laboratori Nazionali di Legnaro (LNL-INFN). The main purpose of the facility is to deliver neutron-rich radioactive beams with a range of mass between 60 and 160 amu produced as fission products originated within a Uranium Carbide (UC x ) target impinged by high energy protons (40–70 MeV). In the last few years, the SPES group and their collaborators have focused on multiple aspects: development of various ISOL targets, ion sources, a high-power beam dump, versatile Front-End designs, primary proton beam and RIB diagnostics, design of beam optic components, and remote target handling. The development and optimization of ionization sources represents one of the most important R&D activities. The collaboration between SPES and ISOLDE (CERN) groups has enabled the evaluation of the performances of a novel FEBIAD ion source taking advantage of the ISOLDE off-line Front-End. In this paper, the results of efficiency and transversal emittance measurements of the new SPES FEBIAD ion source are presented and discussed. Particular attention is dedicated to the description of the experimental setup and to the comparison of experimental data with simulation to promote the reproducibility of the experimental tests with other types of sources.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2025

Laser beam pointing stabilization using analog position-sensitive diodes

Laser wire scanners have been used for ion beam profile and emittance measurements at the Spallation Neutron Source linear accelerator. Due to propagation distances exceeding 100 m, reliable measurements require laser beam stabilization, previously accomplished with a feedback control loop using a digital camera as a position sensor [Hardin et al., Opt. Express 19, 2874 (2011)]. Here, this paper presents an upgraded pointing stabilization system utilizing analog position-sensitive diodes (PSDs) as the position detector, optimized with an optical diffuser. The new system significantly surpasses the previous system by offering an order-of-magnitude improvement in radiation tolerance and a bandwidth limited only by the burst repetition rate of the laser beam. Operating with a 60-Hz burst mode laser, the new system effectively suppresses laser beam drifts up to 30 Hz, compared to the previous system’s 4 Hz limit. In addition, the amplitude of spectral components below 0.1 Hz was reduced by a factor of more than 100, which is over seven times greater than was achieved by the previous system.

Data acquisition↗

DOE OSTI2026

Dynamic evolution of ultracold electron beams from nanostructured cathodes

Dynamic Coulomb expansion of dense, nonuniform particle beamlets can lead to causticlike formations in the charge density profile of the resultant beam. Such features only occur for cold beams where thermal diffusion of the particles is minimized. These phenomena have been observed experimentally for select cases with ion beams but not yet for electron beams as the electron dynamics occur over far faster timescales. We simulate the interaction of electron bunches while varying the initial transverse temperature and density profiles to determine the thresholds that characterize this pattern formation. Furthermore, we extend the simulations to geometric arrangements that are more pertinent to the nanotip cathode application and consider the effects of asymmetries and the impact of a low-density halo on the overall process. The simulations are conducted using a previously documented high-fidelity algorithm for collisional particle dynamics. These studies identify the temperature and density thresholds required for caustic formation and provide guidance for optimizing the design of nanoscale structured cathodes. We also demonstrate that the correlation between the final density patterns and the underlying beam parameters enables a virtual diagnostic tool for measuring ultralow emittance beams solely based on a transverse charge density profile.

43 PARTICLE ACCELERATORS↗

DOE OSTI2022

GEN3D Experimental and Numerical Development of GEN3 Durability Models

Understanding of the high temperature durability of particles and the materials that contain them is critical to next generation of concentrating solar power (CSP) technology. Here we studied the durability of particles and their containment materials under extreme UV cycling, thermal cycling, and in low-speed high temperature mechanical wear situations. The optical stability of seven candidate particles has been determined following exposure to the high temperature conditions present in a generation 3 particle-based CSP technology. Particle solar weighted absorptance and emittance measured periodically during 10,000 high solar irradiance exposure cycles and up to 400 hours of isothermal aging has been documented. The particle aging due to repeated exposure to concentrated solar flux represented the 30-year lifetime of a power plant. Models were fit to the absorptivity and emissivity data following the isothermal aging provides the projected optical degradation of the particles as a function of temperature. Mechanical wear was studied through the use of custom developed wear testing facilities for measuring high temperature impact wear, abrasion wear, and particle attrition. Additionally, a novel technique for measuring the high temperature mechanical properties of single particles was developed. Through these tests it was observed that high nickel alloys generally showed lower wear than comparable iron based steels, particularly at elevated temperatures of 800°C. Mechanical wear at these temperatures is a highly complex phenomenon combining both mechanical wear and oxidation. Additionally, the containment materials wear rates are influenced by the particles (both hardness and roundness), making the wear mechanisms complex. The initial wear test conducted in the abrasion test rig revealed a substantial amount of oxide materials in the particle bed after testing (in relative to later tests), and substantially more wear, likely indicating a need for concern in startup operation of particle facilities to not incur high wear from the presence of oxides. Particle attrition experiments have only been conducted for a single material but increase size distribution, reduction in circularity, and particle diameter is observed. Efforts to develop predictive models was limited due to a testing campaign that prioritized testing materials for particle pathway developers over building a comprehensive design of experiments. The results discussed in this report inform future CSP developers and researchers further de risking the technology and assisting in its future development. ParticleBased CSP development provides a path to dispatchable solar power generation with storage at a price competitive in the current energy market. Lowering the cost of CSP technology provides a carbon free power generation solution that can assist in the transition from fossil fuels to renewable sources of electricity.

14 SOLAR ENERGY↗

DOE OSTI2025

Measurements of source emittance and beam coherence properties of the upgraded Advanced Photon Source

The Advanced Photon Source (APS) has been upgraded with a multi-bend achromat lattice, achieving significantly reduced electron beam emittance and enhanced X-ray coherence. Precise characterization of these properties is essential for optimizing beamline performance and enabling new experiments that take full advantage of the upgraded source. We report on measurements of source size and transverse coherence properties using grating interferometry at two beamlines: the APS 3-ID-B undulator beamline and the 1-BM-B bending magnet beamline. The results confirm the world-record horizontal emittance of the upgraded APS below 30 pm rad and validate the theoretical design parameters. We further investigate the impact of optical aberrations and mechanical vibrations at the 12-ID-C beamline on coherence preservation. These measurements establish a benchmark for future beamline enhancements and demonstrate the effectiveness of grating interferometry for high-precision beam characterization. Our findings provide critical insights into synchrotron beam dynamics, coherence degradation mechanisms, and strategies for optimizing beamline X-ray optics at next-generation light sources.

Advanced Photon Source↗

DOE OSTI2026

Measurement of the Emittance for the CeC Project

Coherent Electron Cooling (CeC) experiment was carried out at RHIC [1]. It required small emi ance of 10-15 MeV electron beam with high peak current. In most cases the emi ance was measured by either quadrupole or solenoid scan. For a low-energy beam with high peak current the measurements are affected by space charge forces. To overcome these difficul es the pepper-pot [2,3] or slit scan [4] can be used.

43 PARTICLE ACCELERATORS↗

DOE OSTI2020

New precise half-life measurement for the superallowed β+ emitter Ar34

We have measured the half-life of 34 Ar, the parent of a superallowed 0 + → 0 + β transition, to be 0.84646(35) s. With a precision of 0.04%, this result is an essential ingredient needed to complete a third pair of mirror superallowed transitions, 34 Ar → 34 Cl and 34 Cl → 34 S, the ratio of whose ft values would provide the most sensitive test yet of the isospin-symmetry-breaking corrections used to obtain V ud . In a sequence repeated thousands of times, we implanted a very pure 34 Ar beam into tape for 0.7 s, and then rapidly transported the collected source to a shielded 4π proportional gas counter, which detected the decay positrons from the combined decays of 34 Ar and its daughter 34 Cl. The data were analyzed as a linked parent-daughter pair. Our new result replaces one we published 13 years ago.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗