s of Articles on Computer Assisted Imaging from Non-Radiological Journals: PHYSICS AND INSTRUMENTATION: PDF Only

The experimental procedure and results of a comparative study the imaging characteristics proton X-ray CT scans are presented. Scans human brain heart discussed. produced images found to be similar in information content while providing decided dose advantage.

The (${\ensuremath{\pi}}^{+}, 2p$) reaction has been studied on targets of $^{2}\mathrm{H}$, $^{6}\mathrm{Li}$, $^{14}\mathrm{N}$, and $^{16}\mathrm{O}$ with 70-MeV pions. All kinematical quantities needed to define completely the final state were determined. data are presented in an unbiased form, integrated over well-defined regions phase space, thus readily comparable available theoretical calculations. Data obtained for opening angles both off kinematics free process,...

Measurements of ${\mathrm{H}}^{\ensuremath{-}}$ stripping and ${\mathrm{H}}^{0}$ excited-state production for a wide range foil thicknesses experimental conditions are reported. An 800-MeV beam was passed through carbon or aluminum oxide foils ranging from 10 to 550 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$ the excited states produced were analyzed by field in special magnet downstream foil. The independently determined. atoms emerging with $n>2$ can be stripped protons fields up 1.3 T. yield...

The conserved-vector-current hypothesis, together with measured nuclear beta-decay rates, predicts a value of the rate for decay ${\ensuremath{\pi}}^{+}$\ensuremath{\rightarrow}${\ensuremath{\pi}}^{0}$${e}^{+}$\ensuremath{\nu} 0.4027\ifmmode\pm\else\textpm\fi{}0.0018 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$. Using decay-in-flight technique we have made most precise measurement to date this rate, obtaining 0.394\ifmmode\pm\else\textpm\fi{}0.015 ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$, in...

Electron cloud instabilities in the Los Alamos Proton Storage Ring and those foreseen for Oak Ridge Spallation Neutron Source are examined theoretically, numerically, experimentally.16 MoreReceived 16 October 2002DOI:https://doi.org/10.1103/PhysRevSTAB.6.014203This article is available under terms of Creative Commons Attribution 3.0 License. Further distribution this work must maintain attribution to author(s) published article’s title, journal citation, DOI.

The Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF) high-energy pion beam (P3) is a three-bend channel with two achromatic output legs designed for high-intensity and moderate resolution. best resolution was measured to be 0.2% in Δp/ p. A phase space of about 25 π mr-cm transmitted by the channel. π+ flux 2 × 107 pions/s 300 MeV/c momentum when 7 μA proton struck 6 cm graphite target. Proton contamination good quality beams up 450 MeV negligible an energy degrader (graphite)...

The lifetime of 800-MeV ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ ions against electron detachment in a static electric field was measured over range eight orders magnitude experiments at the High Resolution Atomic Beam Facility Los Alamos Meson Physics Facility. traversed linear gradient magnetic 1.3-T peak strength resulting 6-MV/cm rest-frame capable stripping large fraction ions. unstripped ions, neutral ${\mathrm{H}}^{0}$ atoms, and protons were detected 5.5 m from magnet. This spectrum...

This paper presents an analytical investigation of the transverse electron-proton ($e\mathrm{\text{\ensuremath{-}}}p$) two-stream instability in a proton bunch propagating through stationary electron background. The equations motion, including damping effects, are derived for centroids beam and cloud by considering Lorentzian Gaussian frequency spreads particles. For distribution, we derive asymptotic solution coupled linear centroid time domain study $e\mathrm{\text{\ensuremath{-}}}p$...

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...

Recent beam physics studies on the two-stream e-p instability at LANL proton storage ring (PSR) have focused role of electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due grazing angle losses from halo. A new diagnostic measure formation and trapping a magnet has been developed, installed, successfully tested PSR. Beam using this show that ``prompt'' flux striking wall is comparable prompt signal adjacent...

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...

The energy gain and motion of electrons can quantitatively describe the mechanism electron multipacting in a long-bunched proton machine. Strong usually happens around bunches' tails due to high when they hit chamber surface. We investigated several important parameters multipacting, proving that it is sensitive beam's intensity, shape its longitudinal profile, transverse size, secondary emission yield, at peak yield. Our analyses, simulations, experiments are all agreement.

In an experiment at the Princeton-Pennsylvania Accelerator, relative rate $\frac{{{K}_{e2}}^{+}}{{{K}_{\ensuremath{\mu}2}}^{+}}$ was measured to be (${1.8}_{\ensuremath{-}0.6}^{+0.8}$) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}5}$. Combining this with previous measurements gives a world average of (${1.9}_{\ensuremath{-}0.4}^{+0.5}$) ${10}^{\ensuremath{-}5}$, which agrees universal $V\ensuremath{-}A$ theory prediction 2.09

A variety of electron cloud diagnostics have been deployed at the Los Alamos Proton Storage Ring (PSR) to detect, measure, and characterize generated in this high intensity, long bunch accumulator ring. These include a version ANL-developed retarding field analyzers (RFA) augmented with LANL-developed electronics, variant RFA denoted as sweeping diagnostic (ESD), biased collection plates, gas pulse measuring devices. The designs experience performance applicability PSR are discussed.

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...

We present studies of space-charge-induced beam profile broadening at high intensities in the Proton Storage Ring (PSR) Los Alamos National Laboratory. investigate through detailed particle-in-cell simulations several experiments and obtain results good agreement with measurements. interpret these within framework coherent resonance theory. With increasing intensity, our show strong evidence for presence a quadrupole-mode envelope lattice vertical plane. Specifically, we observe incoherent...

Beam-loss measurements indicate that 0.2-0.3% of the protons injected into PSR are lost during first turn. We describe a plausible mechanism, involving field stripping excited hydrogen atoms, for these losses. Protons by transporting neutral beam through hole in yoke one ring bender and then carbon foil on axis. The strips roughly 93% atoms to protons. Although original design assumed all unstripped would pass next downstream stop, recent calculations about 6% will emerge from an state with...

Using the ORBIT code we study sensitivity of electron cloud properties with respect to different proton beam profiles, secondary yield (SEY) parameter, and loss rate. Our model uses a cold bunch generate primary electrons electromagnetic field for dynamics. We dependence prompt swept signals vs charge recovery clouds after sweeping on rate SEY. The simulation results are compared experimental data measured at storage ring Los Alamos National Laboratory. simulations indicate that fractional...

The conserved-vector-current hypothesis, together with measured nuclear-beta-decay rates, predicts a value of the rate for decay ${\ensuremath{\pi}}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{e}^{+}\ensuremath{\nu}$ 0.4027\ifmmode\pm\else\textpm\fi{}0.0018 ${\mathrm{s}}^{\ensuremath{-}1}$. With use decay-in-flight technique authors have made most precise measurement to date this rate, obtaining 0.398\ifmmode\pm\else\textpm\fi{}0.015 ${\mathrm{s}}^{\ensuremath{-}1}$, in good agreement...