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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Fiber Optic Picosecond Laser Pulse Transmission Line for Hydrogen Ion Beam Profile Measurement

We present a fiber optic laser pulse transmission line for non-intrusive longitudinal profile measurement of the hydrogen ion (H-) beam at the front-end of the Spallation Neutron Source (SNS) accelerator. The 80.5 MHz, 2.5 ps, multi-killowatt optical pulses are delivered to the accelerator beam line through a large mode area polarization maintaining optical fiber to ensure a high measurement stability. The transmission efficiency, output laser beam quality, pulse jitter and pulse width broadening over a 100-ft fiber line are experimentally investigated. A successful measurement of the H- beam microbunch (~130 ps) profile is obtained. Our experiment is the first demonstration of particle beam profile diagnostics using fiber optic laser pulse transmission line.

fiber optic↗
DOE OSTI2014

Sci—Fri PM: Topics — 05: Experience with linac simulation software in a teaching environment

Medical linear accelerator education is usually restricted to use of academic textbooks and supervised access to accelerators. To facilitate the learning process, simulation software was developed to reproduce the effect of medical linear accelerator beam adjustments on resulting clinical photon beams. The purpose of this report is to briefly describe the method of operation of the software as well as the initial experience with it in a teaching environment. To first and higher orders, all components of medical linear accelerators can be described by analytical solutions. When appropriate calibrations are applied, these analytical solutions can accurately simulate the performance of all linear accelerator sub-components. Grouped together, an overall medical linear accelerator model can be constructed. Fifteen expressions in total were coded using MATLAB v 7.14. The program was called SIMAC. The SIMAC program was used in an accelerator technology course offered at our institution; 14 delegates attended the course. The professional breakdown of the participants was: 5 physics residents, 3 accelerator technologists, 4 regulators and 1 physics associate. The course consisted of didactic lectures supported by labs using SIMAC. At the conclusion of the course, eight of thirteen delegates were able to successfully perform advanced beam adjustments after two days of theory and use of the linac simulator program. We suggest that this demonstrates good proficiency in understanding of the accelerator physics, which we hope will translate to a better ability to understand real world beam adjustments on a functioning medical linear accelerator.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2012

Momentum Cogging at the Fermilab Booster

The Fermilab Booster has an upgrade plan called the Proton Improvement Plan (PIP). The flux throughput goal is 2E17 protons/hour which, is almost double the present flux, 1.1E17 protons/hour. The beam loss in the machine is going to be an issue. The Booster accelerates beam from 400 MeV to 8 GeV and extracts to the Main Injector (MI). The current cogging process synchronizes the extraction kicker gap to the MI by changing radial position of the beam during the cycle. The gap creation occurs at about 700 MeV, which is about 6 ms into the cycle. The cycle-to-cycle variations of the Booster are larger at lower energy. However, changing the radial position at low energy for cogging is limited because of aperture. Momentum cogging is able to move the gap creation to an earlier time by using dipole correctors and radial position feedback, and is able to control the revolution frequency and radial position at the same time. The new cogging is expected to reduce beam loss and not be limited by aperture. The progress of the momentum cogging system development is going to be discussed in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Evaluation of an Alternative Method for Beam Window Temperature Monitoring

A molybdenum-99 production system utilizing a Linac electron source beam and the γ/n reaction on Mo-100 metal targets will employ cooling with high-pressure helium (He) gas. The electron beam will go through a window that separates the high-pressure He gas and the vacuum of the accelerator beam line.

43 PARTICLE ACCELERATORS↗
DOE OSTI2026

Explainable Graph Learning for Particle Accelerator Operations

Particle accelerators are vital tools in physics, medicine, and industry, requiring precise tuning to ensure optimal beam performance. However, real-world deviations from idealized simulations make beam tuning a time-consuming and error-prone process. In this work, we propose an explanation-driven framework for providing actionable insight into beamline operations, with a focus on the injector beamline at the Continuous Electron Beam Accelerator Facility (CEBAF). We represent beamline configurations as heterogeneous graphs, where setting nodes represent elements that human operators can actively adjust during beam tuning, and reading nodes passively provide diagnostic feedback. To identify the most influential setting nodes responsible for differences between any two beamline configurations, our approach first predicts the resulting changes in reading nodes caused by variations in settings, and then learns importance scores that capture the joint influence of multiple setting nodes. Experimental results on real-world CEBAF injector data demonstrate the framework’s ability to generate interpretable insights that can assist human operators in beamline tuning and reduce operational overhead.

Wang, Song [Univ. of Virginia, Charlottesville, VA↗
DOE OSTI2010

Thomas Jefferson National Accelerator Facility

The Thomas Jefferson National Accelerator Facility (Jefferson Lab) in Newport News, Virginia, USA, is one of ten national laboratories under the aegis of the Office of Science of the U.S. Department of Energy (DOE). It is managed and operated by Jefferson Science Associates, LLC. The primary facility at Jefferson Lab is the Continuous Electron Beam Accelerator Facility (CEBAF) as shown in an aerial photograph in Figure 1. Jefferson Lab was created in 1984 as CEBAF and started operations for physics in 1995. The accelerator uses superconducting radio-frequency (srf) techniques to generate high-quality beams of electrons with high-intensity, well-controlled polarization. The technology has enabled ancillary facilities to be created. The CEBAF facility is used by an international user community of more than 1200 physicists for a program of exploration and study of nuclear, hadronic matter, the strong interaction and quantum chromodynamics. Additionally, the exceptional quality of the beams facilitates studies of the fundamental symmetries of nature, which complement those of atomic physics on the one hand and of high-energy particle physics on the other. The facility is in the midst of a project to double the energy of the facility and to enhance and expand its experimental facilities. Studies are also pursued with a Free-Electron Laser produced by an energy-recovering linear accelerator.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

First demonstration of a triton beam using target normal sheath acceleration

Tritiated titanium targets were irradiated by the short-pulse OMEGA EP laser (1.25 kJ, 10 ps) to generate a laser accelerated pulsed beam of tritons by target normal sheath acceleration. Using a Thomson parabola, the beam was found to contain 10 12 tritons per pulse, with a mean energy of 2.2 MeV and an exponential tail reaching up to 10 MeV. In a separate experiment, the triton beam was directed onto a secondary deuterated polyethylene (CD) target to induce deuterium–tritium (D–T) nuclear reactions. Using neutron time-of-flight spectrometers, approximately 10 8 D–T fusion neutrons were observed per laser pulse. Furthermore, this triton beam presents new research opportunities for the study of the 3 H(t, 2n) 4 He reaction and di-neutron transfers to lithium and beryllium that may produce exotic neutron-rich nuclei of interest to basic nuclear science, astrophysics, and inertial confinement fusion technology.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Summary Report for the C50 Cryomodule Project

The Thomas Jefferson National Accelerator Facility has recently completed the C50 cryomodule refurbishment project. The goal of this project was to enable robust 6 GeV, 5 pass operation of the Continuous Electron Beam Accelerator Facility (CEBAF). The scope of the project included removal, refurbishment and reinstallation of ten CEBAF cryomodules at a rate of three per year. The refurbishment process included reprocessing of SRF cavities to eliminate field emission and to increase the nominal gradient from the original 5 MV/m to 12.5 MV/m. New 'dogleg' couplers were installed between the cavity and helium vessel flanges to intercept secondary electrons that produce arcing in the fundamental Power Coupler (FPC). Other changes included new ceramic RF windows for the air to vacuum interface of the FPC and improvements to the mechanical tuner. Damaged or worn components were replaced as well. All ten of the refurbished cryomodules are now installed in CEBAF and are currently operational. This paper will summarize the performance of the cryomodules.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2011

A reef in the sea of instability: Observation of a narrow state in {sup 15}F

The properties of the low lying states of {sup 15}F were studied by measuring the resonant elastic scattering of an {sup 14}O radioactive beam on protons. This experiment was performed at GANIL with a post-accelerated beam produced by the SPIRAL1 facility. We confirm the existence of a second excited state in {sup 15}F with a narrow width, which may seem particularly surprising for a state located above the Coulomb barrier.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Effect of radiation on properties of ENR/PVC/SiO{sub 2} membrane

In this study epoxidised natural rubber (ENR)/polyvinyl chloride (PVC) matrix was prepared by melt blending. The matrix was swelled in THF and silica as a filler was introduced to the solution to generate pore formation. The ENR/PVC/10 % SiO{sub 2} membrane was prepared using a casting knife technique. The membrane was irradiated using 2 MeV electron beam accelerator at a dose range of 10-100 kGy. The effect of electron beam irradiation of the membrane was studied by undergo characterization of Scanning electron microscope (SEM) and Fourier transform infra red (FTIR). Morphological studies showed that pores generated in ENR/PVC/10 % SiO{sub 2} membrane increased with the dosage of radiation. While FTIR analysis showed the presence of peak of Si-O-Si asymmetric stretching at 834 cm{sup −1}. There are no significant changes in the functional group before and after radiation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

A model for radio emission from solar coronal shocks

Solar coronal shocks are very common phenomena in the solar atmosphere and are believed to be the drivers of solar type II radio bursts. However, the microphysical nature of these emissions is still an open question. This paper proposes that electron cyclotron maser (ECM) emission is responsible for the generation of radiation from the coronal shocks. In the present model, an energetic ion beam accelerated by the shock first excites the Alfvén wave (AW), then the excited AW leads to the formation of a density-depleted duct along the foreshock boundary of the shock. In this density-depleted duct, the energetic electron beam produced via the shock acceleration can effectively excite radio emission by ECM instability. Our results show that this model may potentially be applied to solar type II radio bursts.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

Alignment and Aperture Scan at the Fermilab Booster

The Fermilab Booster is currently in the process of an intensity upgrade referred to as the Proton Improvement Plan (PIP). The goal of PIP is to have the Booster provide a proton beam flux of 2 x 10{sup 17} protons/hour. This is almost double the current operation of 1.1 x 10{sup 17} protons/hour. Beam losses in the machine due to the increased flux will create larger integrated doses on aperture limiting components that will need to be mitigated. The Booster accelerates beam from 400 MeV to 8 GeV at a rep rate of 15hz and then extracts beam to the Main Injector. Several percent of the beam is lost within 3 msec after injection in the early part of acceleration. The aperture at injection energy was recently measured using corrector scans. Along with magnet survey data and aperture scan data a plan to realign the magnets in the Booster was developed and implemented in May 2012. The beam studies, analysis of the scan and alignment data, and the result of the magnet moves are presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2022

Proposed Test of the Two Beam BPM at RHIC

The essence of the ERL operation implies that at least two beams (accelerated and decelerated) are co-propagating in the same vacuum vessel and each beam has its own trajectory. The existing beam position monitors measure only “average” trajectory but not that of an individual beam, unless the time separation between bunches is so large that one can resolve individual bunches. It was proposed to use phase information of the pick-up signal to extract information on the orbit “difference”. We are planning to conduct experiments at RHIC to test the proposed idea. The approach and experiment set-up are described in the paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Comparison of measured with calculated dose distribution from a 120-MeV electron beam from a laser-plasma accelerator

Purpose: To evaluate the dose distribution of a 120-MeV laser-plasma accelerated electron beam which may be of potential interest for high-energy electron radiation therapy. Methods: In the interaction between an intense laser pulse and a helium gas jet, a well collimated electron beam with very high energy is produced. A secondary laser beam is used to optically control and to tune the electron beam energy and charge. The potential use of this beam for radiation treatment is evaluated experimentally by measurements of dose deposition in a polystyrene phantom. The results are compared to Monte Carlo simulations using the geant4 code. Results: It has been shown that the laser-plasma accelerated electron beam can deliver a peak dose of more than 1 Gy at the entrance of the phantom in a single laser shot by direct irradiation, without the use of intermediate magnetic transport or focusing. The dose distribution is peaked on axis, with narrow lateral penumbra. Monte Carlo simulations of electron beam propagation and dose deposition indicate that the propagation of the intense electron beam (with large self-fields) can be described by standard models that exclude collective effects in the response of the material. Conclusions: The measurements show that the high-energy electron beams produced by an optically injected laser-plasma accelerator can deliver high enough dose at penetration depths of interest for electron beam radiotherapy of deep-seated tumors. Many engineering issues must be resolved before laser-accelerated electrons can be used for cancer therapy, but they also represent exciting challenges for future research.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2012

Laser-driven proton acceleration using a conical nanobrush target

A conical nanobrush target is proposed to improve the total proton energy-conversion efficiency in proton beam acceleration and investigated by two-dimensional particle-in-cell (2D-PIC) simulations. Results indicate a significant enhancement of the number and energies of hot electrons through the target rear side of the conical nanobrush target. Compared with the plain target, the field increases several times. We observe enhancements of the average proton energy and total laser-proton energy conversion efficiency of 105%. This enhancement is attributed to both nanobrush and conical configurations. The proton beam is well collimated with a divergence angle less than 28{sup Degree-Sign }. The proposed target may serve as a new method for increasing laser to proton energy-conversion efficiency.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

4 K SRF Operation of the 10 MeV CEBAF Photo-Injector

Superconducting radio-frequency (SRF) accelerating cavities are often operated in superfluid liquid helium with temperature near 2 K to enhance the cavity quality factor Q0 and to help manage heat loads, which are particularly important at large SRF accelerator facilities. This 2 K temperature paradigm, however, need not put SRF technology out of the reach of small institutions or even limit SRF operation at large facilities that need 10-100 MeV beam energy. At the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab there are regularly scheduled maintenance periods during which cryogenic plant often increases the liquid helium temperature from 2 K to 4 K, reducing power consumption by ~ 50 % and saving megawatts of wall-plug power. During recent maintenance periods, we accelerated a continuous-wave electron beam at the CEBAF photo-injector to a total energy of 6.3 MeV at currents up to 80 uA using two 5-cell niobium cavities in the quarter-cryomodule at 4 K. This contribution describes the SRF and cryogenic performance and uses measured beam quality and energy stability as key metrics. These measurements indicate that 4 K operation of niobium SRF cavities in CEBAF is a sensible and cost effective mode for high quality beam operation, provided the cryogenic load associated with lower Q0 is manageable for the number of cavities needed to operate. For Jefferson Lab, this enhances our scientific reach allowing additional low-energy ~ 10 MeV experiments each year.

Drury, Michael↗
DOE OSTI2010

IceCube

Neutrino astronomy beyond the Sun was first imagined in the late 1950s; by the 1970s, it was realized that kilometer-scale neutrino detectors were required. The first such instrument, IceCube, is near completion and taking data. Its scientific missions include the observation of Galactic supernova explosions, the search for dark matter, and the study of the neutrinos themselves. These reach energies more than two orders of magnitude beyond those produced by accelerator beams. In these lectures, we will focus on IceCube's most publicized mission, the search for the sources of cosmic rays. We will conclude with an overview of the first results obtained with the partially completed detector.These lectures are based on a review paper co-authored with Spencer Klein (arXiv:astroph.HE/1007.1247) to be published in Review of Scientific Instruments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

A smart alarm for particle accelerator beamline operations

We present the initial results of a proof-of-concept 'smart alarm' for the Continuous Electron Beam Accelerator Facility injector beamline at Jefferson Lab. To minimize machine downtime and improve operational efficiency, an autonomous alarm system able to identify and diagnose unusual machine states is needed. Our approach leverages a trained neural network capable of alerting operators (a) when an anomalous condition exists in the beamline and (b) identifying the element setting that is the root cause. The tool is based on an inverse model that maps beamline readings (diagnostic readbacks) to settings (beamline attributes operators can modify). The model takes as input readings from the machine and computes machine settings which are compared to control setpoints. Instances where predictions differ from setpoints by a user-defined threshold are flagged as anomalous. Given data corresponding to 354 anomalous injector configurations, the model can narrow the root cause of an anomalous condition to three potential candidates with 94.6% accuracy. Furthermore, compared to the current method of identifying anomalous conditions which raises an alarm when machine parameters drift outside their normal tolerances, the data-driven model can identify 83% more anomalous conditions.

43 PARTICLE ACCELERATORS↗