A5102778445- Particle accelerators and beam dynamics
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Radiation Detection and Scintillator Technologies
- Particle Detector Development and Performance
- Laser-Plasma Interactions and Diagnostics
- Gyrotron and Vacuum Electronics Research
- Plasma Diagnostics and Applications
- Atomic and Subatomic Physics Research
- Radiation Effects in Electronics
- Radiation Therapy and Dosimetry
- Diamond and Carbon-based Materials Research
- Advanced Surface Polishing Techniques
- Laser Design and Applications
- Medical Imaging Techniques and Applications
- Nuclear reactor physics and engineering
- Integrated Circuits and Semiconductor Failure Analysis
- Advancements in Photolithography Techniques
- Laser-Matter Interactions and Applications
- Neutrino Physics Research
- Atomic and Molecular Physics
- Nuclear Engineering Thermal-Hydraulics
- Cold Atom Physics and Bose-Einstein Condensates
Oak Ridge National Laboratory
2008-2022
University of Tennessee at Knoxville
2017
Oak Ridge Associated Universities
2016
Spallation Neutron Source
2007
Los Alamos National Laboratory
1988-2004
Los Alamos National Security (United States)
2002
Institute of Particle Physics
1997
We report on an experiment in which a negative hydrogen ion beam the Spallation Neutron Source (SNS) linear accelerator was replaced with of protons similar size and dynamics. Fractional loss superconducting part SNS measured to be at least $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ for ${\mathrm{H}}^{\ensuremath{-}}$ beam, it order magnitude lower protons. Also has stronger dependence intensity than proton beams. These measurements verify recent theoretical explanation...
This Letter reports on the first demonstration of laser-assisted ${\mathrm{H}}^{\ensuremath{-}}$ charge exchange for microsecond duration beam pulses. Laser-assisted injection is a breakthrough technology that overcomes long-standing limitations associated with traditional method producing high intensity, time structured beams protons in accelerators via use carbon foils injection. The central theme this experiment novel techniques reduce laser power requirement to allow efficiency stripping...
Laser-assisted stripping is a novel approach to ${\mathrm{H}}^{\ensuremath{-}}$ charge exchange that overcomes long-standing limitations associated with the traditional, foil-based method of producing high-intensity, time-structured beams protons. This paper reports on first successful demonstration laser technique for microsecond duration beams. The experiment represents factor 1000 increase in stripped pulse compared previous proof-of-principle demonstration. central theme implementation...
The Spallation Neutron Source (SNS) linac accelerates 52-mA peak of pulsed H- particles to over 800 MeV. There are three types accelerating structure in which the beam position must be measured: drift-tube-linac (DTL); cavity-coupled-linac (CCL); and superconducting-linac (SCL)[1, 2]. Beam with a 402.5-MHz is injected into 402.5 MHz DTL, followed by 805-MHz CCL SCL structures. monitor pickups all shorted-microstrip type apertures 2.5-cm, 3-cm 7.3-cm-dia. In cases, we down convert signals...
A strong, fast, transverse instability has long been observed at the Los Alamos Proton Storage Ring (PSR) where it is a limiting factor on peak intensity. Most of available evidence, based measurements unstable proton beam motion, consistent with an electron-proton two-stream instability. The need for higher intensity PSR and future high-intensity, drivers motivated multi-lab collaboration (LANL, ANL, FNAL, LBNL, BNL, ORNL, PPPL) to coordinate research causes, dynamics cures this Important...
The Oak Ridge Spallation Neutron Source comprises a 1 GeV, 1.5 MW linear accelerator followed by an accumulator ring and liquid mercury target. To manage the beam loss caused ${H}^{0}$ excited states created during ${H}^{\ensuremath{-}}$ charge-exchange injection into ring, stripper foil is located inside one of chicane dipoles. This has some interesting consequences that were not fully appreciated until power reached about 840 kW. One consequence was sudden failure system due to convoy...
Transverse beam profiles are observed to broaden with increasing intensity in the Proton Storage Ring at Los Alamos Neutron Scattering Center. Measured simulated an ${\mathrm{H}}^{\ensuremath{-}}$ injection model that includes a 2D particle-in-cell space charge calculation. Inclusion of effects simulation improves agreement between experimentally and calculated profiles. The comparisons made for range injected intensities.
One major concern in the design and operation of high-intensity rings is beam loss due to halo. Another issue importance applications involving fixed targets uniformity energy deposition on target. Both these issues could be favorably addressed by a hard-edged with uniform transverse density. This paper presents detailed feasibility study for painting such into proton ring. For purposes this paper, we define self-consistent beams ellipsoidal, or elliptical 2D, distributions that have density...
The requirement for profile measurements in the SNS superconducting-RF (SRF) linac has presented diagnostic designers with unusual challenges. In addition to making accurate of a high-brightness H/sup -/ beam, device must be compatible 10/sup -10/ Torr vacuum requirements. Also, it cannot impact reliability nearby superconducting structures, either by failure modes, introducing particulate matter, vaporization, or producing excessive radiation levels. We have designed meet these stringent...
The 402.5- and 805-MHz beam position phase monitors for the Spallation Neutron Source linac are based on standard PC technology. SNS is to be injected into a storage ring with 1-MHz circulation frequency requiring 650-ns-long minipulses. injection cycle takes 1 ms machine can run at rates up 60 Hz. RF input signals down converted 50 MHz sampled 40 14-bit ADCs produce I Q data streams. A custom PCI module has been designed accept modular digital front end (DFE) analog (AFE) circuit cards....
The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to liquid mercury target for neutron scattering research. complex consists of an H-injector, capable producing one-ms-long pulses at 60 Hz repetition rate with 38 mA peak current, 1 GeV linear accelerator, accumulator ring and associated transport lines. 2.5 MeV from the Front End is accelerated 86 in Drift Tube Linac, then 185 Coupled-Cavity Linac finally Superconducting Linac. With completion...
The inductance of the vacuum chamber Proton Storage Ring at Los Alamos National Laboratory was intentionally increased by introduction ferrite rings to counteract longitudinal space-charge effect intense beam. magnetic permeability could be adjusted introducing current into solenoids wound around ferrite. Results show that minimum rf voltage necessary stabilize beam against $e\ensuremath{-}p$ instability may reduced over previously measured. injected bunch length observed longer when heavily...
Ion chambers are one of the most popular types detectors used for beam loss-monitor systems. To provide a foundation development future systems, and to fully characterize ion in use at LAMPF, we have studied response air-filled cylindrical high-intensity, short-duration radiation pulses. The intense pulses were about 180 rad 250 ns (the equivalent steady-state dose rate was 700 Mrad/h). We filled our with nitrogen gas 760 Torr air 600 Torr. driven into extreme nonlinear response. hope these...
After a successful demonstration of nonintercepting beam profile monitor for the H/sup -/ beams at 750 KeV and 200 MeV LINAC Brookhaven National Laboratory, SNS project approved using Nd:YAG laser rather than traditional carbon wire transverse monitors in superconducting LINAC. Experiments have also been performed on 2.5 medium energy transport line LBNL. The design implementation multistation monitoring system single will be presented. is scanned across to photoneutralize narrow slices....
A collaboration of six national laboratories, the Spallation Neutron Source (SNS) Project is constructing an accelerator based neutron facility sited in Oak Ridge, Tennessee. The goal 2 MW beam power, 95% availability, and hands-on maintenance will place significant demands on performance operational reliability diagnostics. Mirroring project organization, a cross-laboratory team developing diagnostic systems for facility. This talk reports team's progress summarizes its approach to...
The focus of this tutorial will be on interceptive beam diagnostics such as wire scanners, screens, and harps. We start with an overview the various ways beams interact materials to create signals useful for systems. then discuss errors in a harp or scanner profile measurement caused by position, number samples, signal errors. Finally we apply our results two design examples‐the SNS system target harp.