Modeling the Acceleration of Global Surface Temperture

NASA Astrophysics Data System (ADS)

Jones, B.

2017-12-01

A mathematical projection focusing on the changing rate of acceleration of Global Surface Temperatures. Using historical trajectory and informed expert near-term prediction, it is possible to extend this further forward drawing a reference arc of acceleration. Presented here is an example of this technique based on data found in the Summary of Findings of A New Estimate of the Average Earth Surface Land Temperature Spanning 1753 to 2011 and that same team's stated prediction to 2050. With this, we can project a curve showing future acceleration: Decade (midpoint) Change in Global Land Temp Degrees C Known Slope Projected Trend 1755 0.000 1955 0.600 0.0030 2005 1.500 0.0051 2045 3.000 0.0375 2095 5.485 0.0497 2145 8.895 0.0682 2195 13.488 0.0919 Observations: Slopes are getting steeper and doing so faster in an "acceleration of the acceleration" or an "arc of acceleration". This is consistent with the non-linear accelerating feedback loops of global warming. Such projected temperatures threaten human civilization and human life. This `thumbnail' projection is consistent with the other long term predictions based on anthropogenic greenhouse gases. This projection is low when compared to those whose forecasts include greenhouse gases released from thawing permafrost and clathrate hydrates. A reference line: This curve should be considered a point of reference. In the near term and absent significant drawdown of greenhouse gases, my "bet" for this AGU session is that future temperatures will generally be above this reference curve. For example, the decade ending 2020 - more than 1.9C and the decade ending 2030 - more than 2.3C - again measured from the 1750 start point. *Caveat: The long term curve and prediction assumes that mankind does not move quickly away from high cost fossil fuels and does not invent, mobilize and take actions drawing down greenhouse gases. Those seeking a comprehensive action plan are directed to drawdown.org

A coarse-grid projection method for accelerating incompressible flow computations

NASA Astrophysics Data System (ADS)

San, Omer; Staples, Anne E.

2013-01-01

We present a coarse-grid projection (CGP) method for accelerating incompressible flow computations, which is applicable to methods involving Poisson equations as incompressibility constraints. The CGP methodology is a modular approach that facilitates data transfer with simple interpolations and uses black-box solvers for the Poisson and advection-diffusion equations in the flow solver. After solving the Poisson equation on a coarsened grid, an interpolation scheme is used to obtain the fine data for subsequent time stepping on the full grid. A particular version of the method is applied here to the vorticity-stream function, primitive variable, and vorticity-velocity formulations of incompressible Navier-Stokes equations. We compute several benchmark flow problems on two-dimensional Cartesian and non-Cartesian grids, as well as a three-dimensional flow problem. The method is found to accelerate these computations while retaining a level of accuracy close to that of the fine resolution field, which is significantly better than the accuracy obtained for a similar computation performed solely using a coarse grid. A linear acceleration rate is obtained for all the cases we consider due to the linear-cost elliptic Poisson solver used, with reduction factors in computational time between 2 and 42. The computational savings are larger when a suboptimal Poisson solver is used. We also find that the computational savings increase with increasing distortion ratio on non-Cartesian grids, making the CGP method a useful tool for accelerating generalized curvilinear incompressible flow solvers.

SLAC modulator system improvements and reliability results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donaldson, A.R.

1998-06-01

In 1995, an improvement project was completed on the 244 klystron modulators in the linear accelerator. The modulator system has been previously described. This article offers project details and their resulting effect on modulator and component reliability. Prior to the project, the authors had collected four operating cycles (1991 through 1995) of MTTF data. In this discussion, the '91 data will be excluded since the modulators operated at 60 Hz. The five periods following the '91 run were reviewed due to the common repetition rate at 120 Hz.

MO-FG-BRC-02: Low-Z Switching Linear Accelerator Targets: New Options for Image Guidance and Dose Enhancement in Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robar, J.

2016-06-15

Experimental research in medical physics has expanded the limits of our knowledge and provided novel imaging and therapy technologies for patients around the world. However, experimental efforts are challenging due to constraints in funding, space, time and other forms of institutional support. In this joint ESTRO-AAPM symposium, four exciting experimental projects from four different countries are highlighted. Each project is focused on a different aspect of radiation therapy. From the USA, we will hear about a new linear accelerator concept for more compact and efficient therapy devices. From Canada, we will learn about novel linear accelerator target design and themore » implications for imaging and therapy. From France, we will discover a mature translational effort to incorporate theranostic nanoparticles in MR-guided radiation therapy. From Germany, we will find out about a novel in-treatment imaging modality for particle therapy. These examples of high impact, experimental medical physics research are representative of the diversity of such efforts that are on-going around the globe. J. Robar, Research is supported through collaboration with Varian Medical Systems and Brainlab AGD. Westerly, This work is supported by the Department of Radiation Oncology at the University of Colorado School of Medicine. COI: NONEK. Parodi, Part of the presented work is supported by the DFG (German Research Foundation) Cluster of Excellence MAP (Munich-Centre for Advanced Photonics) and has been carried out in collaboration with IBA.« less

A coarse-grid-projection acceleration method for finite-element incompressible flow computations

NASA Astrophysics Data System (ADS)

Kashefi, Ali; Staples, Anne; FiN Lab Team

2015-11-01

Coarse grid projection (CGP) methodology provides a framework for accelerating computations by performing some part of the computation on a coarsened grid. We apply the CGP to pressure projection methods for finite element-based incompressible flow simulations. Based on it, the predicted velocity field data is restricted to a coarsened grid, the pressure is determined by solving the Poisson equation on the coarse grid, and the resulting data are prolonged to the preset fine grid. The contributions of the CGP method to the pressure correction technique are twofold: first, it substantially lessens the computational cost devoted to the Poisson equation, which is the most time-consuming part of the simulation process. Second, it preserves the accuracy of the velocity field. The velocity and pressure spaces are approximated by Galerkin spectral element using piecewise linear basis functions. A restriction operator is designed so that fine data are directly injected into the coarse grid. The Laplacian and divergence matrices are driven by taking inner products of coarse grid shape functions. Linear interpolation is implemented to construct a prolongation operator. A study of the data accuracy and the CPU time for the CGP-based versus non-CGP computations is presented. Laboratory for Fluid Dynamics in Nature.

Ultra-high vacuum photoelectron linear accelerator

DOEpatents

Yu, David U.L.; Luo, Yan

2013-07-16

An rf linear accelerator for producing an electron beam. The outer wall of the rf cavity of said linear accelerator being perforated to allow gas inside said rf cavity to flow to a pressure chamber surrounding said rf cavity and having means of ultra high vacuum pumping of the cathode of said rf linear accelerator. Said rf linear accelerator is used to accelerate polarized or unpolarized electrons produced by a photocathode, or to accelerate thermally heated electrons produced by a thermionic cathode, or to accelerate rf heated field emission electrons produced by a field emission cathode.

Prototyping of beam position monitor for medium energy beam transport section of RAON heavy ion accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jang, Hyojae, E-mail: lkcom@ibs.re.kr; Jin, Hyunchang; Jang, Ji-Ho

2016-02-15

A heavy ion accelerator, RAON is going to be built by Rare Isotope Science Project in Korea. Its target is to accelerate various stable ions such as uranium, proton, and xenon from electron cyclotron resonance ion source and some rare isotopes from isotope separation on-line. The beam shaping, charge selection, and modulation should be applied to the ions from these ion sources because RAON adopts a superconducting linear accelerator structure for beam acceleration. For such treatment, low energy beam transport, radio frequency quadrupole, and medium energy beam transport (MEBT) will be installed in injector part of RAON accelerator. Recently, developmentmore » of a prototype of stripline beam position monitor (BPM) to measure the position of ion beams in MEBT section is under way. In this presentation, design of stripline, electromagnetic (EM) simulation results, and RF measurement test results obtained from the prototyped BPM will be described.« less

A New Active Space Radiation Instruments for the International Space Station, A-DREAMS

NASA Astrophysics Data System (ADS)

Uchihori, Yukio; Kodaira, Satoshi; Kitamura, Hisashi; Kobayashi, Shingo

For future space experiments in the International Space Station (ISS) or other satellites, radiation detectors, A-DREAMS (Active Dosimeter for Radiation Environment and Astronautic Monitoring in Space), using single or multiple silicon semi-conductor detectors have been developed. The first version of the detectors were produced and calibrated with particle accelerators. National Institute of Radiological Sciences has a medical heavy ion accelerator (HIMAC) for cancer therapy and a cyclotron accelerator. The detector was irradiated with high energy heavy ions and protons in HIMAC and the cyclotron and calibrated the energy resolution and linearity for deposited energies of these particles. We are planned to be going to use the new instrument in an international project, the new MATROSHKA experiment which is directed by members in the Institute of Bio-Medical Problem (IBMP) in Russia and German Space Center (DLR) in Germany. In the project, the dose distribution in human torso phantom will be investigated for several months in the ISS. For the project, a new type of the instruments is under development in NIRS and the current situation will be reported in this paper.

Grid Effect on Spherical Shallow Water Jets Using Continuous and Discontinuous Galerkin Methods

DTIC Science & Technology

2013-01-01

The high-order Legendre -Gauss-Lobatto (LGL) points are added to the linear grid by projecting the linear elements onto the auxiliary gnomonic space...mapping, the triangles are subdivided into smaller ones by a Lagrange polynomial of order nI . The number of quadrilateral elements and grid points of...of the acceleration of gravity and the vertical height of the fluid), ν∇2 is the artificial viscosity term of viscous coefficient ν = 1× 105 m2 s−1

An overview of beam diagnostic and control systems for 50 MeV AREAL Linac

NASA Astrophysics Data System (ADS)

Sargsyan, A. A.; Amatuni, G. A.; Sahakyan, V. V.; Zanyan, G. S.; Martirosyan, N. W.; Vardanyan, V. V.; Grigoryan, B. A.

2017-03-01

Advanced Research Electron Accelerator Laboratory (AREAL) is an electron linear accelerator project with a laser driven RF gun being constructed at CANDLE Synchrotron Research Institute. After the successful operation of the gun section at 5 MeV, a program of facility energy enhancement up to 50 MeV is launched. In this paper the current status of existing diagnostic and control systems, as well as the results of electron beam parameter measurements are presented. The approaches of intended diagnostic and control systems for the upgrade program are also described.

LINEAR COLLIDER PHYSICS RESOURCE BOOK FOR SNOWMASS 2001.

DOE Office of Scientific and Technical Information (OSTI.GOV)

ABE,T.; DAWSON,S.; HEINEMEYER,S.

The American particle physics community can look forward to a well-conceived and vital program of experimentation for the next ten years, using both colliders and fixed target beams to study a wide variety of pressing questions. Beyond 2010, these programs will be reaching the end of their expected lives. The CERN LHC will provide an experimental program of the first importance. But beyond the LHC, the American community needs a coherent plan. The Snowmass 2001 Workshop and the deliberations of the HEPAP subpanel offer a rare opportunity to engage the full community in planning our future for the next decademore » or more. A major accelerator project requires a decade from the beginning of an engineering design to the receipt of the first data. So it is now time to decide whether to begin a new accelerator project that will operate in the years soon after 2010. We believe that the world high-energy physics community needs such a project. With the great promise of discovery in physics at the next energy scale, and with the opportunity for the uncovering of profound insights, we cannot allow our field to contract to a single experimental program at a single laboratory in the world. We believe that an e{sup +}e{sup {minus}} linear collider is an excellent choice for the next major project in high-energy physics. Applying experimental techniques very different from those used at hadron colliders, an e{sup +}e{sup {minus}} linear collider will allow us to build on the discoveries made at the Tevatron and the LHC, and to add a level of precision and clarity that will be necessary to understand the physics of the next energy scale. It is not necessary to anticipate specific results from the hadron collider programs to argue for constructing an e{sup +}e{sup {minus}} linear collider; in any scenario that is now discussed, physics will benefit from the new information that e{sup +}e{sup {minus}} experiments can provide.« less

Linear Collider Physics Resource Book for Snowmass 2001

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peskin, Michael E

The American particle physics community can look forward to a well-conceived and vital program of experimentation for the next ten years, using both colliders and fixed target beams to study a wide variety of pressing questions. Beyond 2010, these programs will be reaching the end of their expected lives. The CERN LHC will provide an experimental program of the first importance. But beyond the LHC, the American community needs a coherent plan. The Snowmass 2001 Workshop and the deliberations of the HEPAP subpanel offer a rare opportunity to engage the full community in planning our future for the next decademore » or more. A major accelerator project requires a decade from the beginning of an engineering design to the receipt of the first data. So it is now time to decide whether to begin a new accelerator project that will operate in the years soon after 2010. We believe that the world high-energy physics community needs such a project. With the great promise of discovery in physics at the next energy scale, and with the opportunity for the uncovering of profound insights, we cannot allow our field to contract to a single experimental program at a single laboratory in the world. We believe that an e{sup +}e{sup -} linear collider is an excellent choice for the next major project in high-energy physics. Applying experimental techniques very different from those used at hadron colliders, an e{sup +}e{sup -} linear collider will allow us to build on the discoveries made at the Tevatron and the LHC, and to add a level of precision and clarity that will be necessary to understand the physics of the next energy scale. It is not necessary to anticipate specific results from the hadron collider programs to argue for constructing an e{sup +}e{sup -} linear collider; in any scenario that is now discussed, physics will benefit from the new information that e{sup +}e{sup -} experiments can provide.« less

Design for simultaneous acceleration of stable and unstable beams in a superconducting heavy-ion linear accelerator for RISP

NASA Astrophysics Data System (ADS)

Kim, Jongwon; Son, Hyock-Jun; Park, Young-Ho

2017-11-01

The post-accelerator of isotope separation on-line (ISOL) system for rare isotope science project (RISP) is a superconducting linear accelerator (SC-linac) with a DC equivalent voltage of around 160 MV. An isotope beam extracted from the ISOL is in a charge state of 1+ and its charge state is increased to n+ by charge breeding with an electron beam ion source (EBIS). The charge breeding takes tens of ms and the pulse width of extracted beam from the EBIS is tens of μs, which operates at up to 30 Hz. Consequently a large portion of radio frequency (rf) time of the post SC-linac is unused. The post-linac is equipped also with an electron cyclotron resonance (ECR) ion source for stable ion acceleration. Thanks to the large phase acceptance of SC-linac, it is possible to accelerate simultaneously both stable and radioisotope ions with a similar charge to mass ratio by sharing rf time. This operation scheme is implemented for RISP with the addition of an electric chopper and magnetic kickers. The facility will be capable of providing the users of the ISOL and in-flight fragmentation (IF) systems with different beams simultaneously, which would help nuclear science users in obtaining a beam time as high-precision measurements often need long hours.

Investigation of using shrinking method in construction of Institute for Research in Fundamental Sciences Electron Linear Accelerator TW-tube (IPM TW-Linac tube)

NASA Astrophysics Data System (ADS)

Ghasemi, F.; Abbasi Davani, F.

2015-06-01

Due to Iran's growing need for accelerators in various applications, IPM's electron Linac project has been defined. This accelerator is a 15 MeV energy S-band traveling-wave accelerator which is being designed and constructed based on the klystron that has been built in Iran. Based on the design, operating mode is π /2 and the accelerating chamber consists of two 60cm long tubes with constant impedance and a 30cm long buncher. Amongst all construction methods, shrinking method is selected for construction of IPM's electron Linac tube because it has a simple procedure and there is no need for large vacuum or hydrogen furnaces. In this paper, different aspects of this method are investigated. According to the calculations, linear ratio of frequency alteration to radius change is 787.8 MHz/cm, and the maximum deformation at the tube wall where disks and the tube make contact is 2.7μ m. Applying shrinking method for construction of 8- and 24-cavity tubes results in satisfactory frequency and quality factor. Average deviations of cavities frequency of 8- and 24-cavity tubes to the design values are 0.68 MHz and 1.8 MHz respectively before tune and 0.2 MHz and 0.4 MHz after tune. Accelerating tubes, buncher, and high power couplers of IPM's electron linac are constructed using shrinking method.

Assembly and commissioning of a new SRF cryomodule for the ATLAS intensity upgrade

NASA Astrophysics Data System (ADS)

Conway, Z. A.; Barcikowski, A.; Cherry, G. L.; Fischer, R. L.; Fuerst, J. D.; Jansma, W. G.; Gerbick, S. M.; Kedzie, M. J.; Kelly, M. P.; Kim, S. H.; MacDonald, S. W. T.; Murphy, R. C.; Ostroumov, P. N.; Reid, T. C.; Shepard, K. W.

2014-01-01

The Argonne National Laboratory Physics Division is in the final stages of a major upgrade to the Argonne Tandem Linear Accelerator System national user facility, referred to as the intensity upgrade. The intensity upgrade project will substantially increase beam currents for experimenters working with the existing ATLAS stable and in-flight rare isotope beams and for the neutron-rich beams from the Californium Rare Isotope Breeder Upgrade. This project includes the replacement of three existing cryomodules, containing 18 superconducting accelerator cavities and 9 superconducting solenoids, with a single cryomodule with seven SC 72.75 MHz accelerator cavities optimized for ion velocities of 7.7% the speed of light and 4 SC solenoids all operating at 4.5 K. This presentation will report: how we minimized the heat load into the 4 K and 80 K coolant streams feeding the cryomodule, a comparison of the calculated and measured static heat loads at 80 K and the mechanical design of the vacuum vessel.

Report of the Fermilab ILC Citizens' Task Force

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Fermi National Accelerator Laboratory convened the ILC Citizens' Task Force to provide guidance and advice to the laboratory to ensure that community concerns and ideas are included in all public aspects of planning and design for a proposed future accelerator, the International Linear Collider. In this report, the members of the Task Force describe the process they used to gather and analyze information on all aspects of the proposed accelerator and its potential location at Fermilab in northern Illinois. They present the conclusions and recommendations they reached as a result of the learning process and their subsequent discussions and deliberations.more » While the Task Force was charged to provide guidance on the ILC, it became clear during the process that the high cost of the proposed accelerator made a near-term start for the project at Fermilab unlikely. Nevertheless, based on a year of extensive learning and dialogue, the Task Force developed a series of recommendations for Fermilab to consider as the laboratory develops all successor projects to the Tevatron. The Task Force recognizes that bringing a next-generation particle physics project to Fermilab will require both a large international effort and the support of the local community. While the Task Force developed its recommendations in response to the parameters of a future ILC, the principles they set forth apply directly to any large project that may be conceived at Fermilab, or at other laboratories, in the future. With this report, the Task Force fulfills its task of guiding Fermilab from the perspective of the local community on how to move forward with a large-scale project while building positive relationships with surrounding communities. The report summarizes the benefits, concerns and potential impacts of bringing a large-scale scientific project to northern Illinois.« less

Optimal Model-Based Fault Estimation and Correction for Particle Accelerators and Industrial Plants Using Combined Support Vector Machines and First Principles Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sayyar-Rodsari, Bijan; Schweiger, Carl; /SLAC /Pavilion Technologies, Inc., Austin, TX

2010-08-25

Timely estimation of deviations from optimal performance in complex systems and the ability to identify corrective measures in response to the estimated parameter deviations has been the subject of extensive research over the past four decades. The implications in terms of lost revenue from costly industrial processes, operation of large-scale public works projects and the volume of the published literature on this topic clearly indicates the significance of the problem. Applications range from manufacturing industries (integrated circuits, automotive, etc.), to large-scale chemical plants, pharmaceutical production, power distribution grids, and avionics. In this project we investigated a new framework for buildingmore » parsimonious models that are suited for diagnosis and fault estimation of complex technical systems. We used Support Vector Machines (SVMs) to model potentially time-varying parameters of a First-Principles (FP) description of the process. The combined SVM & FP model was built (i.e. model parameters were trained) using constrained optimization techniques. We used the trained models to estimate faults affecting simulated beam lifetime. In the case where a large number of process inputs are required for model-based fault estimation, the proposed framework performs an optimal nonlinear principal component analysis of the large-scale input space, and creates a lower dimension feature space in which fault estimation results can be effectively presented to the operation personnel. To fulfill the main technical objectives of the Phase I research, our Phase I efforts have focused on: (1) SVM Training in a Combined Model Structure - We developed the software for the constrained training of the SVMs in a combined model structure, and successfully modeled the parameters of a first-principles model for beam lifetime with support vectors. (2) Higher-order Fidelity of the Combined Model - We used constrained training to ensure that the output of the SVM (i.e. the parameters of the beam lifetime model) are physically meaningful. (3) Numerical Efficiency of the Training - We investigated the numerical efficiency of the SVM training. More specifically, for the primal formulation of the training, we have developed a problem formulation that avoids the linear increase in the number of the constraints as a function of the number of data points. (4) Flexibility of Software Architecture - The software framework for the training of the support vector machines was designed to enable experimentation with different solvers. We experimented with two commonly used nonlinear solvers for our simulations. The primary application of interest for this project has been the sustained optimal operation of particle accelerators at the Stanford Linear Accelerator Center (SLAC). Particle storage rings are used for a variety of applications ranging from 'colliding beam' systems for high-energy physics research to highly collimated x-ray generators for synchrotron radiation science. Linear accelerators are also used for collider research such as International Linear Collider (ILC), as well as for free electron lasers, such as the Linear Coherent Light Source (LCLS) at SLAC. One common theme in the operation of storage rings and linear accelerators is the need to precisely control the particle beams over long periods of time with minimum beam loss and stable, yet challenging, beam parameters. We strongly believe that beyond applications in particle accelerators, the high fidelity and cost benefits of a combined model-based fault estimation/correction system will attract customers from a wide variety of commercial and scientific industries. Even though the acquisition of Pavilion Technologies, Inc. by Rockwell Automation Inc. in 2007 has altered the small business status of the Pavilion and it no longer qualifies for a Phase II funding, our findings in the course of the Phase I research have convinced us that further research will render a workable model-based fault estimation and correction for particle accelerators and industrial plants feasible.« less

GPU-accelerated iterative reconstruction for limited-data tomography in CBCT systems.

PubMed

de Molina, Claudia; Serrano, Estefania; Garcia-Blas, Javier; Carretero, Jesus; Desco, Manuel; Abella, Monica

2018-05-15

Standard cone-beam computed tomography (CBCT) involves the acquisition of at least 360 projections rotating through 360 degrees. Nevertheless, there are cases in which only a few projections can be taken in a limited angular span, such as during surgery, where rotation of the source-detector pair is limited to less than 180 degrees. Reconstruction of limited data with the conventional method proposed by Feldkamp, Davis and Kress (FDK) results in severe artifacts. Iterative methods may compensate for the lack of data by including additional prior information, although they imply a high computational burden and memory consumption. We present an accelerated implementation of an iterative method for CBCT following the Split Bregman formulation, which reduces computational time through GPU-accelerated kernels. The implementation enables the reconstruction of large volumes (>1024 3 pixels) using partitioning strategies in forward- and back-projection operations. We evaluated the algorithm on small-animal data for different scenarios with different numbers of projections, angular span, and projection size. Reconstruction time varied linearly with the number of projections and quadratically with projection size but remained almost unchanged with angular span. Forward- and back-projection operations represent 60% of the total computational burden. Efficient implementation using parallel processing and large-memory management strategies together with GPU kernels enables the use of advanced reconstruction approaches which are needed in limited-data scenarios. Our GPU implementation showed a significant time reduction (up to 48 ×) compared to a CPU-only implementation, resulting in a total reconstruction time from several hours to few minutes.

Linear Accelerator (LINAC)

MedlinePlus

... equipment? How is safety ensured? What is this equipment used for? A linear accelerator (LINAC) is the ... Therapy (SBRT) . top of page How does the equipment work? The linear accelerator uses microwave technology (similar ...

Industrialization of Superconducting RF Accelerator Technology

NASA Astrophysics Data System (ADS)

Peiniger, Michael; Pekeler, Michael; Vogel, Hanspeter

2012-01-01

Superconducting RF (SRF) accelerator technology has basically existed for 50 years. It took about 20 years to conduct basic R&D and prototyping at universities and international institutes before the first superconducting accelerators were built, with industry supplying complete accelerator cavities. In parallel, the design of large scale accelerators using SRF was done worldwide. In order to build those accelerators, industry has been involved for 30 years in building the required cavities and/or accelerator modules in time and budget. To enable industry to supply these high tech components, technology transfer was made from the laboratories in the following three regions: the Americas, Asia and Europe. As will be shown, the manufacture of the SRF cavities is normally accomplished in industry whereas the cavity testing and module assembly are not performed in industry in most cases, yet. The story of industrialization is so far a story of customized projects. Therefore a real SRF accelerator product is not yet available in this market. License agreements and technology transfer between leading SRF laboratories and industry is a powerful tool for enabling industry to manufacture SRF components or turnkey superconducting accelerator modules for other laboratories and users with few or no capabilities in SRF technology. Despite all this, the SRF accelerator market today is still a small market. The manufacture and preparation of the components require a range of specialized knowledge, as well as complex and expensive manufacturing installations like for high precision machining, electron beam welding, chemical surface preparation and class ISO4 clean room assembly. Today, the involved industry in the US and Europe comprises medium-sized companies. In Japan, some big enterprises are involved. So far, roughly 2500 SRF cavities have been built by or ordered from industry worldwide. Another substantial step might come from the International Linear Collider (ILC) project currently being designed by the international collaboration GDE (`global design effort'). If the ILC will be built, about 18,000 SRF cavities need to be manufactured worldwide within about five years. The industrialization of SRF accelerator technology is analyzed and reviewed in this article in view of the main accelerator projects of the last two to three decades.

Field stabilization studies for a radio frequency quadrupole accelerator

NASA Astrophysics Data System (ADS)

Gaur, R.; Kumar, V.

2014-07-01

The Radio Frequency Quadrupole (RFQ) linear accelerator is an accelerator that efficiently focuses, bunches and accelerates a high intensity DC beam from an ion source, for various applications. Unlike other conventional RF linear accelerators, the electromagnetic mode used for its operation is not the lowest frequency mode supported by the structure. In a four vane type RFQ, there are several undesired electromagnetic modes having frequency close to that of the operating mode. While designing an RFQ accelerator, care must be taken to ensure that the frequencies of these nearby modes are sufficiently separated from the operating mode. If the undesired nearby modes have frequencies close to the operating mode, the electromagnetic field pattern in the presence of geometrical errors will not be stabilized to the desired field profile, and will be perturbed by the nearby modes. This will affect the beam dynamics and reduce the beam transmission. In this paper, we present a detailed study of the electromagnetic modes supported, which is followed by calculations for implementation of suitable techniques to make the desired operating mode stable against mixing with unwanted modes for an RFQ being designed for the proposed Indian Spallation Neutron Source (ISNS) project at Raja Ramanna Centre for Advanced Technology, Indore. Resonant coupling scheme, along with dipole stabilization rods has been proposed to increase the mode separation. The paper discusses the details of a generalized optimization procedure that has been used for the design of mode stabilization scheme.

Extraordinary Tools for Extraordinary Science: The Impact ofSciDAC on Accelerator Science&Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryne, Robert D.

2006-08-10

Particle accelerators are among the most complex and versatile instruments of scientific exploration. They have enabled remarkable scientific discoveries and important technological advances that span all programs within the DOE Office of Science (DOE/SC). The importance of accelerators to the DOE/SC mission is evident from an examination of the DOE document, ''Facilities for the Future of Science: A Twenty-Year Outlook''. Of the 28 facilities listed, 13 involve accelerators. Thanks to SciDAC, a powerful suite of parallel simulation tools has been developed that represent a paradigm shift in computational accelerator science. Simulations that used to take weeks or more now takemore » hours, and simulations that were once thought impossible are now performed routinely. These codes have been applied to many important projects of DOE/SC including existing facilities (the Tevatron complex, the Relativistic Heavy Ion Collider), facilities under construction (the Large Hadron Collider, the Spallation Neutron Source, the Linac Coherent Light Source), and to future facilities (the International Linear Collider, the Rare Isotope Accelerator). The new codes have also been used to explore innovative approaches to charged particle acceleration. These approaches, based on the extremely intense fields that can be present in lasers and plasmas, may one day provide a path to the outermost reaches of the energy frontier. Furthermore, they could lead to compact, high-gradient accelerators that would have huge consequences for US science and technology, industry, and medicine. In this talk I will describe the new accelerator modeling capabilities developed under SciDAC, the essential role of multi-disciplinary collaboration with applied mathematicians, computer scientists, and other IT experts in developing these capabilities, and provide examples of how the codes have been used to support DOE/SC accelerator projects.« less

Extraordinary tools for extraordinary science: the impact of SciDAC on accelerator science and technology

NASA Astrophysics Data System (ADS)

Ryne, Robert D.

2006-09-01

Particle accelerators are among the most complex and versatile instruments of scientific exploration. They have enabled remarkable scientific discoveries and important technological advances that span all programs within the DOE Office of Science (DOE/SC). The importance of accelerators to the DOE/SC mission is evident from an examination of the DOE document, ''Facilities for the Future of Science: A Twenty-Year Outlook.'' Of the 28 facilities listed, 13 involve accelerators. Thanks to SciDAC, a powerful suite of parallel simulation tools has been developed that represent a paradigm shift in computational accelerator science. Simulations that used to take weeks or more now take hours, and simulations that were once thought impossible are now performed routinely. These codes have been applied to many important projects of DOE/SC including existing facilities (the Tevatron complex, the Relativistic Heavy Ion Collider), facilities under construction (the Large Hadron Collider, the Spallation Neutron Source, the Linac Coherent Light Source), and to future facilities (the International Linear Collider, the Rare Isotope Accelerator). The new codes have also been used to explore innovative approaches to charged particle acceleration. These approaches, based on the extremely intense fields that can be present in lasers and plasmas, may one day provide a path to the outermost reaches of the energy frontier. Furthermore, they could lead to compact, high-gradient accelerators that would have huge consequences for US science and technology, industry, and medicine. In this talk I will describe the new accelerator modeling capabilities developed under SciDAC, the essential role of multi-disciplinary collaboration with applied mathematicians, computer scientists, and other IT experts in developing these capabilities, and provide examples of how the codes have been used to support DOE/SC accelerator projects.

Linear accelerator radiosurgery for arteriovenous malformations: Updated literature review.

PubMed

Yahya, S; Heyes, G; Nightingale, P; Lamin, S; Chavda, S; Geh, I; Spooner, D; Cruickshank, G; Sanghera, P

2017-04-01

Arteriovenous malformations (AVMs) are the leading causing of intra-cerebral haemorrhage. Stereotactic radiosurgery (SRS) is an established treatment for arteriovenous malformations (AVM) and commonly delivered using Gamma Knife within dedicated radiosurgery units. Linear accelerator (LINAC) SRS is increasingly available however debate remains over whether it offers an equivalent outcome. The aim of this project is to evaluate the outcomes using LINAC SRS for AVMs used within a UK neurosciences unit and review the literature to aid decision making across various SRS platforms. Results have shown comparability across platforms and strongly supports that an adapted LINAC based SRS facility within a dynamic regional neuro-oncology department delivers similar outcomes (in terms of obliteration and toxicity) to any other dedicated radio-surgical platform. Locally available facilities can facilitate discussion between options however throughput will inevitably be lower than centrally based dedicated national radiosurgery units. Copyright © 2016. Published by Elsevier Ltd.

Voltage regulation in linear induction accelerators

DOEpatents

Parsons, William M.

1992-01-01

Improvement in voltage regulation in a Linear Induction Accelerator wherein a varistor, such as a metal oxide varistor, is placed in parallel with the beam accelerating cavity and the magnetic core. The non-linear properties of the varistor result in a more stable voltage across the beam accelerating cavity than with a conventional compensating resistance.

Is Africa a 'Graveyard' for Linear Accelerators?

PubMed

Reichenvater, H; Matias, L Dos S

2016-12-01

Linear accelerator downtimes are common and problematic in many African countries and may jeopardise the outcome of affected radiation treatments. The predicted increase in cancer incidence and prevalence on the African continent will require, inter alia, improved response with regard to a reduction in linear accelerator downtimes. Here we discuss the problems associated with the maintenance and repair of linear accelerators and propose alternative solutions relevant for local conditions in African countries. The paper is based on about four decades of experience in capacity building, installing, commissioning, calibrating, servicing and repairing linear accelerators in Africa, where about 40% of the low and middle income countries in the world are geographically located. Linear accelerators can successfully be operated, maintained and repaired in African countries provided proper maintenance and repair plans are put in place and executed. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Beam dynamics simulation of a double pass proton linear accelerator

DOE PAGES

Hwang, Kilean; Qiang, Ji

2017-04-03

A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fullymore » 3D space-charge effects through the entire accelerator system.« less

The Role of Linear Acceleration in Visual-Vestibular Interactions and Implications in Aircraft Operations

NASA Technical Reports Server (NTRS)

Correia, Manning J.; Luke, Brian L.; McGrath, Braden J.; Clark, John B.; Rupert, Angus H.

1996-01-01

While considerable attention has been given to visual-vestibular interaction (VVI) during angular motion of the head as might occur during an aircraft spin, much less attention has been given to VVI during linear motion of the head. Such interaction might occur, for example, while viewing a stationary or moving display during vertical take-off and landing operations Research into linear VVI, particularly during prolonged periods of linear acceleration, has been hampered by the unavailability of a programmable translator capable of large excursions We collaborated with Otis Elevator Co. and used their research tower and elevator, whose motion could be digitally programmed, to vertically translate human subjects over a distance of 92.3 meters with a peak linear acceleration of 2 meters/sec(exp 2) During pulsatile or sinusoidal translation, the subjects viewed moving stripes (optokinetic stimulus) or a fixed point source (light emitting diode, led, display), respectively and it was generally found that. The direction of linear acceleration relative to the cardinal head axes and the direction of the slow component of optokinetic nystagmus (OKN) determined the extent of VVI during concomitant stripe motion and linear acceleration. Acceleration along the z head axis (A(sub z)) produced the largest VVI, particularly when the slow component of OKN was in the same direction as eye movements produced by the linear acceleration and Eye movements produced by linear acceleration are suppressed by viewing a fixed target at frequencies below 10 Hz But, above this frequency the suppression produced by VVI is removed. Finally, as demonstrated in non-human primates, vergence of the eyes appears to modulate the vertical eye movement response to linear acceleration in humans.

Study on radiation production in the charge stripping section of the RISP linear accelerator

NASA Astrophysics Data System (ADS)

Oh, Joo-Hee; Oranj, Leila Mokhtari; Lee, Hee-Seock; Ko, Seung-Kook

2015-02-01

The linear accelerator of the Rare Isotope Science Project (RISP) accelerates 200 MeV/nucleon 238U ions in a multi-charge states. Many kinds of radiations are generated while the primary beam is transported along the beam line. The stripping process using thin carbon foil leads to complicated radiation environments at the 90-degree bending section. The charge distribution of 238U ions after the carbon charge stripper was calculated by using the LISE++ program. The estimates of the radiation environments were carried out by using the well-proved Monte Carlo codes PHITS and FLUKA. The tracks of 238U ions in various charge states were identified using the magnetic field subroutine of the PHITS code. The dose distribution caused by U beam losses for those tracks was obtained over the accelerator tunnel. A modified calculation was applied for tracking the multi-charged U beams because the fundamental idea of PHITS and FLUKA was to transport fully-ionized ion beam. In this study, the beam loss pattern after a stripping section was observed, and the radiation production by heavy ions was studied. Finally, the performance of the PHITS and the FLUKA codes was validated for estimating the radiation production at the stripping section by applying a modified method.

Voltage regulation in linear induction accelerators

DOEpatents

Parsons, W.M.

1992-12-29

Improvement in voltage regulation in a linear induction accelerator wherein a varistor, such as a metal oxide varistor, is placed in parallel with the beam accelerating cavity and the magnetic core is disclosed. The non-linear properties of the varistor result in a more stable voltage across the beam accelerating cavity than with a conventional compensating resistance. 4 figs.

Biased optimal guidance for a bank-to-turn missile

NASA Astrophysics Data System (ADS)

Stallard, D. V.

A practical terminal-phase guidance law for controlling the pitch acceleration and roll rate of a bank-to-turn missile with zero autopilot lags was derived and tested, so as to minimize squared miss distance without requiring overly large commands. An acceleration bias is introduced to prevent excessive roll commands due to noise. The Separation Theorem is invoked and the guidance (control) law is derived by applying optimal control theory, linearizing the nonlinear plant equation around the present missile orientation, and obtaining a closed-form solution. The optimal pitch-acceleration and roll-rate commands are respectively proportional to two components of the projected, constant-bias, miss distance, with a resemblance to earlier derivations and proportional navigation. Simulaiation results and other related work confirm the suitability of the guidance law.

Design of a diamond-crystal monochromator for the LCLS hard x-ray self-seeding project

NASA Astrophysics Data System (ADS)

Shu, D.; Shvyd'ko, Y.; Amann, J.; Emma, P.; Stoupin, S.; Quintana, J.

2013-03-01

As the result of collaborations between the Advanced Photon Source (APS), Argonne National Laboratory, and the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory, we have designed and constructed a diamond crystal monochromator for the LCLS hard x-ray self-seeding project. The novel monochromator is ultrahigh-vacuum compatible to meet the LCLS linear accelerator vacuum environmental requirement. A special graphite holder was designed for strain-free mount of the 110-μm thin synthetic diamond crystal plate provided by Technological Institute for Super-hard and Novel Carbon Materials of Russia (TISNCM). An in-vacuum multi-axis precision positioning mechanism is designed to manipulate the thin-film diamond holder with resolutions and stabilities required by the hard x-ray self-seeding physics. Optical encoders, limit switches, and hardware stops are established in the mechanism to ensure system reliability and to meet the accelerator personal and equipment safety interlock requirements. Molybdenum shields are installed in the monochromator to protect the encoders and associated electronics from radiation damage. Mechanical specifications, designs, and preliminary test results of the diamond monochromator are presented in this paper.

The Spallation Neutron Source accelerator system design

NASA Astrophysics Data System (ADS)

Henderson, S.; Abraham, W.; Aleksandrov, A.; Allen, C.; Alonso, J.; Anderson, D.; Arenius, D.; Arthur, T.; Assadi, S.; Ayers, J.; Bach, P.; Badea, V.; Battle, R.; Beebe-Wang, J.; Bergmann, B.; Bernardin, J.; Bhatia, T.; Billen, J.; Birke, T.; Bjorklund, E.; Blaskiewicz, M.; Blind, B.; Blokland, W.; Bookwalter, V.; Borovina, D.; Bowling, S.; Bradley, J.; Brantley, C.; Brennan, J.; Brodowski, J.; Brown, S.; Brown, R.; Bruce, D.; Bultman, N.; Cameron, P.; Campisi, I.; Casagrande, F.; Catalan-Lasheras, N.; Champion, M.; Champion, M.; Chen, Z.; Cheng, D.; Cho, Y.; Christensen, K.; Chu, C.; Cleaves, J.; Connolly, R.; Cote, T.; Cousineau, S.; Crandall, K.; Creel, J.; Crofford, M.; Cull, P.; Cutler, R.; Dabney, R.; Dalesio, L.; Daly, E.; Damm, R.; Danilov, V.; Davino, D.; Davis, K.; Dawson, C.; Day, L.; Deibele, C.; Delayen, J.; DeLong, J.; Demello, A.; DeVan, W.; Digennaro, R.; Dixon, K.; Dodson, G.; Doleans, M.; Doolittle, L.; Doss, J.; Drury, M.; Elliot, T.; Ellis, S.; Error, J.; Fazekas, J.; Fedotov, A.; Feng, P.; Fischer, J.; Fox, W.; Fuja, R.; Funk, W.; Galambos, J.; Ganni, V.; Garnett, R.; Geng, X.; Gentzlinger, R.; Giannella, M.; Gibson, P.; Gillis, R.; Gioia, J.; Gordon, J.; Gough, R.; Greer, J.; Gregory, W.; Gribble, R.; Grice, W.; Gurd, D.; Gurd, P.; Guthrie, A.; Hahn, H.; Hardek, T.; Hardekopf, R.; Harrison, J.; Hatfield, D.; He, P.; Hechler, M.; Heistermann, F.; Helus, S.; Hiatt, T.; Hicks, S.; Hill, J.; Hill, J.; Hoff, L.; Hoff, M.; Hogan, J.; Holding, M.; Holik, P.; Holmes, J.; Holtkamp, N.; Hovater, C.; Howell, M.; Hseuh, H.; Huhn, A.; Hunter, T.; Ilg, T.; Jackson, J.; Jain, A.; Jason, A.; Jeon, D.; Johnson, G.; Jones, A.; Joseph, S.; Justice, A.; Kang, Y.; Kasemir, K.; Keller, R.; Kersevan, R.; Kerstiens, D.; Kesselman, M.; Kim, S.; Kneisel, P.; Kravchuk, L.; Kuneli, T.; Kurennoy, S.; Kustom, R.; Kwon, S.; Ladd, P.; Lambiase, R.; Lee, Y. Y.; Leitner, M.; Leung, K.-N.; Lewis, S.; Liaw, C.; Lionberger, C.; Lo, C. C.; Long, C.; Ludewig, H.; Ludvig, J.; Luft, P.; Lynch, M.; Ma, H.; MacGill, R.; Macha, K.; Madre, B.; Mahler, G.; Mahoney, K.; Maines, J.; Mammosser, J.; Mann, T.; Marneris, I.; Marroquin, P.; Martineau, R.; Matsumoto, K.; McCarthy, M.; McChesney, C.; McGahern, W.; McGehee, P.; Meng, W.; Merz, B.; Meyer, R.; Meyer, R.; Miller, B.; Mitchell, R.; Mize, J.; Monroy, M.; Munro, J.; Murdoch, G.; Musson, J.; Nath, S.; Nelson, R.; Nelson, R.; O`Hara, J.; Olsen, D.; Oren, W.; Oshatz, D.; Owens, T.; Pai, C.; Papaphilippou, I.; Patterson, N.; Patterson, J.; Pearson, C.; Pelaia, T.; Pieck, M.; Piller, C.; Plawski, T.; Plum, M.; Pogge, J.; Power, J.; Powers, T.; Preble, J.; Prokop, M.; Pruyn, J.; Purcell, D.; Rank, J.; Raparia, D.; Ratti, A.; Reass, W.; Reece, K.; Rees, D.; Regan, A.; Regis, M.; Reijonen, J.; Rej, D.; Richards, D.; Richied, D.; Rode, C.; Rodriguez, W.; Rodriguez, M.; Rohlev, A.; Rose, C.; Roseberry, T.; Rowton, L.; Roybal, W.; Rust, K.; Salazer, G.; Sandberg, J.; Saunders, J.; Schenkel, T.; Schneider, W.; Schrage, D.; Schubert, J.; Severino, F.; Shafer, R.; Shea, T.; Shishlo, A.; Shoaee, H.; Sibley, C.; Sims, J.; Smee, S.; Smith, J.; Smith, K.; Spitz, R.; Staples, J.; Stein, P.; Stettler, M.; Stirbet, M.; Stockli, M.; Stone, W.; Stout, D.; Stovall, J.; Strelo, W.; Strong, H.; Sundelin, R.; Syversrud, D.; Szajbler, M.; Takeda, H.; Tallerico, P.; Tang, J.; Tanke, E.; Tepikian, S.; Thomae, R.; Thompson, D.; Thomson, D.; Thuot, M.; Treml, C.; Tsoupas, N.; Tuozzolo, J.; Tuzel, W.; Vassioutchenko, A.; Virostek, S.; Wallig, J.; Wanderer, P.; Wang, Y.; Wang, J. G.; Wangler, T.; Warren, D.; Wei, J.; Weiss, D.; Welton, R.; Weng, J.; Weng, W.-T.; Wezensky, M.; White, M.; Whitlatch, T.; Williams, D.; Williams, E.; Wilson, K.; Wiseman, M.; Wood, R.; Wright, P.; Wu, A.; Ybarrolaza, N.; Young, K.; Young, L.; Yourd, R.; Zachoszcz, A.; Zaltsman, A.; Zhang, S.; Zhang, W.; Zhang, Y.; Zhukov, A.

2014-11-01

The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. Department of Energy national laboratories. The SNS accelerator system consists of a 1 GeV linear accelerator and an accumulator ring providing 1.4 MW of proton beam power in microsecond-long beam pulses to a liquid mercury target for neutron production. The accelerator complex consists of a front-end negative hydrogen-ion injector system, an 87 MeV drift tube linear accelerator, a 186 MeV side-coupled linear accelerator, a 1 GeV superconducting linear accelerator, a 248-m circumference accumulator ring and associated beam transport lines. The accelerator complex is supported by ~100 high-power RF power systems, a 2 K cryogenic plant, ~400 DC and pulsed power supply systems, ~400 beam diagnostic devices and a distributed control system handling ~100,000 I/O signals. The beam dynamics design of the SNS accelerator is presented, as is the engineering design of the major accelerator subsystems.

Drift tube suspension for high intensity linear accelerators

DOEpatents

Liska, D.J.; Schamaun, R.G.; Clark, D.C.; Potter, R.C.; Frank, J.A.

1980-03-11

The disclosure relates to a drift tube suspension for high intensity linear accelerators. The system comprises a series of box-sections girders independently adjustably mounted on a linear accelerator. A plurality of drift tube holding stems are individually adjustably mounted on each girder.

TU-E-BRA-11: Volume of Interest Cone Beam CT with a Low-Z Linear Accelerator Target: Proof-of-Concept.

PubMed

Robar, J; Parsons, D; Berman, A; MacDonald, A

2012-06-01

This study demonstrates feasibility and advantages of volume of interest (VOI) cone beam CT (CBCT) imaging performed with an x-ray beam generated from 2.35 MeV electrons incident on a carbon linear accelerator target. The electron beam energy was reduced to 2.35 MeV in a Varian 21EX linear accelerator containing a 7.6 mm thick carbon x-ray target. Arbitrary imaging volumes were defined in the planning system to produce dynamic MLC sequences capable of tracking off-axis VOIs in phantoms. To reduce truncation artefacts, missing data in projection images were completed using a priori DRR information from the planning CT set. The feasibility of the approach was shown through imaging of an anthropomorphic phantom and the head-and-neck section of a lamb. TLD800 and EBT2 radiochromic film measurements were used to compare the VOI dose distributions with those for full-field techniques. CNR was measured for VOIs ranging from 4 to 15 cm diameter. The 2.35 MV/Carbon beam provides favorable CNR characteristics, although marked boundary and cupping artefacts arise due to truncation of projection data. These artefacts are largely eliminated using the DRR filling technique. Imaging dose was reduced by 5-10% and 75% inside and outside of the VOI, respectively, compared to full-field imaging for a cranial VOI. For the 2.35 MV/Carbon beam, CNR was shown to be approximately invariant with VOI dimension for bone and lung objects. This indicates that the advantage of the VOI approach with the low-Z target beam is substantial imaging dose reduction, not improvement of image quality. VOI CBCT using a 2.35 MV/Carbon beam is a feasible technique whereby a chosen imaging volume can be defined in the planning system and tracked during acquisition. The novel x-ray beam affords good CNR characteristics while imaging dose is localized to the chosen VOI. Funding for this project has been received from Varian Medical, Incorporated. © 2012 American Association of Physicists in Medicine.

Design and commissioning of a 16.1 MHz multiharmonic buncher for the reaccelerator at NSCL

NASA Astrophysics Data System (ADS)

Alt, Daniel Maloney

The ReAccelerator (ReA) linear accelerator facility at the National Superconducting Cyclotron Laboratory is a unique resource for the nuclear physics community. The particle fragmentation beam production technique, combined with the ability to stop and then reaccelerate the beam to energies of astrophysical interest, give experimenters an unprecedented range of rare isotopes at energies of nuclear and astrophysical interest. The ReAccelerator also functions as a testbed for technology to be incorporated in the upcoming Facility for Rare Isotope Beams linear accelerator, which will eventually in turn become the beam source for ReA. This prototype nature of the ReAccelerator, however, dictated some design choices which have resulted in a final beam with a time structure that is less than ideal for certain classes of experiments. The cavities and RFQ used in ReA have an operating frequency of 80.5 MHz, which corresponds to a separation between particle bunches at the detectors of 12.4 ns. While this separation is acceptable for many experiments, sensitive time of flight measurements require a greater separation between pulses. As nuclear physics experiments rely on statistics, a solution to increasing bunch separation without simply discarding a large fraction of the beam particles was desired. This document describes the design and construction of such a device, a 16.1 MHz multiharmonic buncher. The first chapter provides backgound information on the NSCL and ReA, and some basic concepts in accelerator physics to lay the groundwork for the project.Next, more specifics are provided on the time structure of accelerated beams, and the experimental motivation for greater separation. The third chapter outlines the basic principles of multiharmonic bunching. In order to evaluate the feasibility of any buncher design, the exact acceptance of the Radiofrequency Quadrupole (RFQ) of the ReAccelerator needed to be empirically measured. Chapter 4 describes the results of that measurement. Chapter 5 outlines the simulations and calculations that went into the design choices for this particular buncher, incorporating the results of the RFQ measurements. The next two chapters describe the construction, installation, and testing of the device, and give experimental results. Finally, Chapter 8 summarizes the project and the final steps which need to be undertaken to make the device a simple to use asset for future experimentalists at ReA.

Design, Modeling and Simulations in the RACE Project: Preliminary study for the development of a transport line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maidana, C. O.; Hunt, A. W.; Idaho State University, Department of Physics, PO Box 8106, Pocatello, ID 83209

2007-02-12

As part of the Reactor Accelerator Coupling Experiment (RACE) a set of preliminary studies were conducted to design a transport beam line that could bring a 25 MeV electron beam from a Linear Accelerator to a neutron-producing target inside a subcritical system. Because of the relatively low energy beam, the beam size and a relatively long beam line (implicating a possible divergence problem) different parameters and models were studied before a final design could be submitted for assembly. This report shows the first results obtained from different simulations of the transport line optics and dynamics.

Luminosity Limitations of Linear Colliders Based on Plasma Acceleration

DOE PAGES

Lebedev, Valeri; Burov, Alexey; Nagaitsev, Sergei

2016-01-01

Particle acceleration in plasma creates a possibility of exceptionally high accelerating gradients and appears as a very attractive option for future linear electron-positron and/or photon-photon colliders. These high accelerating gradients were already demonstrated in a number of experiments. Furthermore, a linear collider requires exceptionally high beam brightness which still needs to be demonstrated. In this article we discuss major phenomena which limit the beam brightness of accelerated beam and, consequently, the collider luminosity.

Poster — Thur Eve — 28: Enabling trajectory-based radiotherapy on a TrueBeam accelerator with the Eclipse treatment planning system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullins, J; Asiev, K; DeBlois, F

2014-08-15

The TrueBeam linear accelerator platform has a developer's mode which permits the user dynamic control over many of the machine's mechanical and radiation systems. Using this research tool, synchronous couch and gantry motion can be programmed to simulate isocentric treatment with a shortened SAD, with benefits such as smaller projected MLC leaf widths and an increased dose rate. In this work, water tank measurements were used to commission a virtual linear accelerator with an 85 cm SAD in Eclipse, from which several arc-based radiotherapy treatments were generated, including an inverse optimized VMAT delivery. For each plan, the pertinent treatment deliverymore » information was extracted from control points specified in the Eclipse-exported DICOM files using the pydicom package in Python, allowing construction of an XML control file. The dimensions of the jaws and MLC positions, defined for an 85 cm SAD in Eclipse, were scaled for delivery on a conventional SAD linear accelerator, and translational couch motion was added as a function of gantry angle to simulate delivery at 85 cm SAD. Ionization chamber and Gafchromic film measurements were used to compare the radiation delivery to dose calculations in Eclipse. With the exception of the VMAT delivery, ionization chamber measurements agreed within 3.3% of the Eclipse calculations. For the VMAT delivery, the ionization chamber was located in an inhomogeneous region, but gamma evaluation of the Gafchromic film plane resulted in a 94.5% passing rate using criteria of 3 mm/3%. The results indicate that Eclipse calculation infrastructure can be used.« less

Evaluation of proton cross-sections for radiation sources in the proton accelerator

NASA Astrophysics Data System (ADS)

Cho, Young-Sik; Lee, Cheol-Woo; Lee, Young-Ouk

2007-08-01

Proton Engineering Frontier Project (PEFP) is currently building a proton accelerator in Korea which consists of a proton linear accelerator with 100 MeV of energy, 20 mA of current and various particle beam facilities. The final goal of this project consists of the production of 1 GeV proton beams, which will be used for various medical and industrial applications as well as for research in basic and applied sciences. Carbon and copper in the proton accelerator for PEPP, through activation, become radionuclides such as 7Be and 64Cu. Copper is a major element of the accelerator components and the carbon is planned to be used as a target material of the beam dump. A recent survey showed that the currently available cross-sections create a large difference from the experimental data in the production of some residual nuclides by the proton-induced reactions for carbon and copper. To more accurately estimate the production of radioactive nuclides in the accelerator, proton cross-sections for carbon and copper are evaluated. The TALYS code was used for the evaluation of the cross-sections for the proton-induced reactions. To obtain the cross-sections which best fits the experimental data, optical model parameters for the neutron, proton and other complex particles such as the deuteron and alpha were successively adjusted. The evaluated cross-sections in this study are compared with the measurements and other evaluations .

Mirror symmetric optics design for charge-stripping section in Rare Isotope Science Project

NASA Astrophysics Data System (ADS)

Kim, Hye-Jin; Kim, Hyung-Jin; Jeon, Dong-O.; Hwang, Ji-Gwang; Kim, Eun-San

2013-12-01

The main aim of the Rare Isotope Science Project is to construct a high power heavy-ion accelerator based on the superconducting linear accelerator (SCL). The heavy ion accelerator is a key research facility that will allow ground-breaking research into numerous facets of basic science, such as nuclear physics, astrophysics, atomic physics, life science, medicine and material science. The machine will provide a beam power of 400 kW with a 238U79+ beam of 8 pμA and 200 MeV/u. One of the critical components in the SCL is the charge stripper between the two segments, SCL1 and SCL2, of the SCL. The charge stripper removes electrons from the ion beams to enhance the acceleration efficiency in the subsequent SCL2. To improve the efficiency of acceleration and power in SCL2, the optimal energy of stripped ions in a solid carbon foil stripper was estimated using the code LISE++. The thickness of the solid carbon foil was 300 μg/m2. The charge stripping efficiency of the solid carbon stripper in the present study was approximately 87%. For charge selection from the ions produced by the solid carbon stripper, a dispersive section is needed down-stream of the foil. The designed optics for the dispersive section is based on the mirror-symmetric optics to minimize the effect of high-order aberrations.

Femtosecond Electron and Photon Pulses Facility in Thailand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rimjaem, S.; Thongbai, C.; Jinamoon, V.

Femtosecond electron and photon pulses facility has been established as SURIYA project at the Fast Neutron Research Facility (FNRF). Femtosecond electron bunches can be generated from a system consisting of an RF gun with a thermionic cathode, an alpha magnet as an magnetic bunch compressor, and a linear accelerator as a post acceleration section. Femtosecond electron pulses can be used directly or used as a source to produce equally short electromagnetic (EM) radiation pulses via certain kind of radiation production processes. At SURIYA project, we are interested especially in production of radiation in Far-infrared (FIR) regime. At these wavelengths, themore » radiation from femtosecond electron pulses is emitted coherently resulting in high intensity radiation. Overview of the facility, the generation of femtosecond electron bunches, the theoretical background of coherent transition radiation and the recent experimental results will be presented and discussed in this paper.« less

FFAGs: Front-end for neutrino factories and medical accelerators

NASA Astrophysics Data System (ADS)

Mori, Yoshiharu

The idea of Fixed Field Alternating Gradient (FFAG) accelerator was originated by different people and groups in the early 1950s. It was independently introduced by Ohkawa [Ohkawa (1953)], Symon et al. [Symon et al. (1956)], and Kolomensky [Kolomensky and Lebedev (1966)] when the strong Alternate Gradient (AG) focusing and the phase stability schemes were applied to particle acceleration. The first FFAG electron model was developed in the MURA accelerator project led by Kerst and Cole in the late 1950s. Since then, they have fabricated several electron models in the early 1960s [Symon et al. (1956)]. However, the studies did not lead to a single practical FFAG accelerator for the following 50 years. Because of the difficulties of treating non-linear magnetic field and RF acceleration for non-relativistic particles, the proton FFAG, especially, was not accomplished until recently. In 2000, the FFAG concept was revived with the world's first proton FFAG (POP) which was developed at KEK [Aiba (2000); Mori (1999)]. Since then, in many places [Berg (2004); Johnstone et al. (2004); Mori (2011); Ruggiero (2004); Trbojevic (2004)], FFAGs have been developed and constructed...

Design of four-beam IH-RFQ linear accelerator

NASA Astrophysics Data System (ADS)

Ikeda, Shota; Murata, Aki; Hayashizaki, Noriyosu

2017-09-01

The multi-beam acceleration method is an acceleration technique for low-energy high-intensity heavy ion beams, which involves accelerating multiple beams to decrease space charge effects, and then integrating these beams by a beam funneling system. At the Tokyo Institute of Technology a two beam IH-RFQ linear accelerator was developed using a two beam laser ion source with direct plasma injection scheme. This system accelerated a carbon ion beam with a current of 108 mA (54 mA/channel × 2) from 5 up to 60 keV/u. In order to demonstrate that a four-beam IH-RFQ linear accelerator is suitable for high-intensity heavy ion beam acceleration, we have been developing a four-beam prototype. A four-beam IH-RFQ linear accelerator consists of sixteen RFQ electrodes (4 × 4 set) with stem electrodes installed alternately on the upper and lower ridge electrodes. As a part of this development, we have designed a four-beam IH-RFQ linear accelerator using three dimensional electromagnetic simulation software and beam tracking simulation software. From these simulation results, we have designed the stem electrodes, the center plate and the side shells by evaluating the RF properties such as the resonance frequency, the power loss and the electric strength distribution between the RFQ electrodes.

Design, characterization, and control of the NASA three degree of freedom reaction compensation platform

NASA Technical Reports Server (NTRS)

Birkhimer, Craig; Newman, Wyatt; Choi, Benjamin; Lawrence, Charles

1994-01-01

Increasing research is being done into industrial uses for the microgravity environment aboard orbiting space vehicles. However, there is some concern over the effects of reaction forces produced by moving objects, especially motors, robotic actuators, and astronauts. Reaction forces produced by the movement of these objects may manifest themselves as undesirable accelerations in the space vehicle making the vehicle unusable for microgravity applications. It is desirable to provide compensation for such forces using active means. This paper presents the design and experimental evaluation of the NASA three degree of freedom reaction compensation platform, a system designed to be a testbed for the feasibility of active attenuation of reaction forces caused by moving objects in a microgravity environment. Unique 'linear motors,' which convert electrical current directly into rectilinear force, are used in the platform design. The linear motors induce accelerations of the displacer inertias. These accelerations create reaction forces that may be controlled to counteract disturbance forces introduced to the platform. The stated project goal is to reduce reaction forces by 90 percent, or -20 dB. Description of the system hardware, characterization of the actuators and the composite system, and design of the software safety system and control software are included.

TU-H-BRA-06: Characterization of a Linear Accelerator Operating in a Compact MRIGuided Radiation Therapy System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, O; Mutic, S; Li, H

2016-06-15

Purpose: To describe the performance of a linear accelerator operating in a compact MRI-guided radiation therapy system. Methods: A commercial linear accelerator was placed in an MRI unit that is employed in a commercial MR-based image guided radiation therapy (IGRT) system. The linear accelerator components were placed within magnetic field-reducing hardware that provided magnetic fields of less than 40 G for the magnetron, gun driver, and port circulator, with 1 G for the linear accelerator. The system did not employ a flattening filter. The test linear accelerator was an industrial 4 MV model that was employed to test the abilitymore » to run an accelerator in the MR environment. An MR-compatible diode detector array was used to measure the beam profiles with the accelerator outside and inside the MR field and with the gradient coils on and off to examine if there was any effect on the delivered dose distribution. The beam profiles and time characteristics of the beam were measured. Results: The beam profiles exhibited characteristic unflattened Bremsstrahlung features with less than ±1.5% differences in the profile magnitude when the system was outside and inside the magnet and less than 1% differences with the gradient coils on and off. The central axis dose rate fluctuated by less than 1% over a 30 second period when outside and inside the MRI. Conclusion: A linaccompatible MR design has been shown to be effective in not perturbing the operation of a commercial linear accelerator. While the accelerator used in the tests was 4MV, there is nothing fundamentally different with the operation of a 6MV unit, implying that the design will enable operation of the proposed clinical unit. Research funding provided by ViewRay, Inc.« less

Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields.

PubMed

An, Weiming; Lu, Wei; Huang, Chengkun; Xu, Xinlu; Hogan, Mark J; Joshi, Chan; Mori, Warren B

2017-06-16

Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of less than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. The underlying physics that leads to the lower than expected emittance growth is elucidated.

Feasibility of an XUV FEL Oscillator Driven by a SCRF Linear Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumpkin, A. H.; Freund, H. P.; Reinsch, M.

The Advanced Superconducting Test Accelerator (ASTA) facility is currently under construction at Fermi National Accelerator Laboratory. Using a1-ms-long macropulse composed of up to 3000 micropulses, and with beam energies projected from 45 to 800 MeV, the possibility for an extreme ultraviolet (XUV) free-electron laser oscillator (FELO) with the higher energy is evaluated. We have used both GINGER with an oscillator module and the MEDUSA/OPC code to assess FELO saturation prospects at 120 nm, 40 nm, and 13.4 nm. The results support saturation at all of these wavelengths which are also shorter than the demonstrated shortest wavelength record of 176 nmmore » from a storage-ring-based FELO. This indicates linac-driven FELOs can be extended into this XUV wavelength regime previously only reached with single-pass FEL configurations.« less

Luis Alvarez, the Hydrogen Bubble Chamber, Tritium, and Dinosaurs

Science.gov Websites

linear accelerator, patented three types of radar still used today, designed an instrument that for 15 is available in documents and on the Web. Documents: Berkeley Proton Linear Accelerator, DOE Technical Report Download Adobe PDF Reader , June 1985 History of Proton Linear Accelerators, DOE Technical

Terahertz-driven linear electron acceleration

PubMed Central

Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; Ravi, Koustuban; Fallahi, Arya; Moriena, Gustavo; Dwayne Miller, R. J.; Kärtner, Franz X.

2015-01-01

The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeV m−1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. These ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams. PMID:26439410

Terahertz-driven linear electron acceleration

DOE PAGES

Nanni, Emilio A.; Huang, Wenqian R.; Hong, Kyung-Han; ...

2015-10-06

The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30–50 MeVm -1 gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/protonmore » accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. As a result, these ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.« less

High-efficiency acceleration in the laser wakefield by a linearly increasing plasma density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Kegong; Wu, Yuchi; Zhu, Bin

The acceleration length and the peak energy of the electron beam are limited by the dephasing effect in the laser wakefield acceleration with uniform plasma density. Based on 2D-3V particle in cell simulations, the effects of a linearly increasing plasma density on the electron acceleration are investigated broadly. Comparing with the uniform plasma density, because of the prolongation of the acceleration length and the gradually increasing accelerating field due to the increasing plasma density, the electron beam energy is twice higher in moderate nonlinear wakefield regime. Because of the lower plasma density, the linearly increasing plasma density can also avoidmore » the dark current caused by additional injection. At the optimal acceleration length, the electron energy can be increased from 350 MeV (uniform) to 760 MeV (linearly increasing) with the energy spread of 1.8%, the beam duration is 5 fs and the beam waist is 1.25 μm. This linearly increasing plasma density distribution can be achieved by a capillary with special gas-filled structure, and is much more suitable for experiment.« less

MO-F-16A-02: Simulation of a Medical Linear Accelerator for Teaching Purposes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlone, M; Lamey, M; Anderson, R

Purpose: Detailed functioning of linear accelerator physics is well known. Less well developed is the basic understanding of how the adjustment of the linear accelerator's electrical components affects the resulting radiation beam. Other than the text by Karzmark, there is very little literature devoted to the practical understanding of linear accelerator functionality targeted at the radiotherapy clinic level. The purpose of this work is to describe a simulation environment for medical linear accelerators with the purpose of teaching linear accelerator physics. Methods: Varian type lineacs were simulated. Klystron saturation and peak output were modelled analytically. The energy gain of anmore » electron beam was modelled using load line expressions. The bending magnet was assumed to be a perfect solenoid whose pass through energy varied linearly with solenoid current. The dose rate calculated at depth in water was assumed to be a simple function of the target's beam current. The flattening filter was modelled as an attenuator with conical shape, and the time-averaged dose rate at a depth in water was determined by calculating kerma. Results: Fifteen analytical models were combined into a single model called SIMAC. Performance was verified systematically by adjusting typical linac control parameters. Increasing klystron pulse voltage increased dose rate to a peak, which then decreased as the beam energy was further increased due to the fixed pass through energy of the bending magnet. Increasing accelerator beam current leads to a higher dose per pulse. However, the energy of the electron beam decreases due to beam loading and so the dose rate eventually maximizes and the decreases as beam current was further increased. Conclusion: SIMAC can realistically simulate the functionality of a linear accelerator. It is expected to have value as a teaching tool for both medical physicists and linear accelerator service personnel.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, Kilean; Qiang, Ji

A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fullymore » 3D space-charge effects through the entire accelerator system.« less

A system for monitoring the radiation effects of a proton linear accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skorkin, V. M., E-mail: skorkin@inr.ru; Belyanski, K. L.; Skorkin, A. V.

2016-12-15

The system for real-time monitoring of radioactivity of a high-current proton linear accelerator detects secondary neutron emission from proton beam losses in transport channels and measures the activity of radionuclides in gas and aerosol emissions and the radiation background in the environment affected by a linear accelerator. The data provided by gamma, beta, and neutron detectors are transferred over a computer network to the central server. The system allows one to monitor proton beam losses, the activity of gas and aerosol emissions, and the radiation emission level of a linear accelerator in operation.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlone, Marco; Harnett, Nicole; Jaffray, David

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 ofmore » 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.« less

Variable-energy drift-tube linear accelerator

DOEpatents

Swenson, Donald A.; Boyd, Jr., Thomas J.; Potter, James M.; Stovall, James E.

1984-01-01

A linear accelerator system includes a plurality of post-coupled drift-tubes wherein each post coupler is bistably positionable to either of two positions which result in different field distributions. With binary control over a plurality of post couplers, a significant accumlative effect in the resulting field distribution is achieved yielding a variable-energy drift-tube linear accelerator.

Variable-energy drift-tube linear accelerator

DOEpatents

Swenson, D.A.; Boyd, T.J. Jr.; Potter, J.M.; Stovall, J.E.

A linear accelerator system includes a plurality of post-coupled drift-tubes wherein each post coupler is bistably positionable to either of two positions which result in different field distributions. With binary control over a plurality of post couplers, a significant accumlative effect in the resulting field distribution is achieved yielding a variable-energy drift-tube linear accelerator.

Free electron lasers driven by linear induction accelerators: High power radiation sources

NASA Technical Reports Server (NTRS)

Orzechowski, T. J.

1989-01-01

The technology of Free Electron Lasers (FELs) and linear induction accelerators (LIAs) is addressed by outlining the following topics: fundamentals of FELs; basic concepts of linear induction accelerators; the Electron Laser Facility (a microwave FEL); PALADIN (an infrared FEL); magnetic switching; IMP; and future directions (relativistic klystrons). This presentation is represented by viewgraphs only.

Accelerator Science: Circular vs. Linear

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lincoln, Don

Particle accelerator are scientific instruments that allow scientists to collide particles together at incredible energies to study the secrets of the universe. However, there are many manners in which particle accelerators can be constructed. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of circular and linear accelerators.

Computation of linear acceleration through an internal model in the macaque cerebellum

PubMed Central

Laurens, Jean; Meng, Hui; Angelaki, Dora E.

2013-01-01

A combination of theory and behavioral findings has supported a role for internal models in the resolution of sensory ambiguities and sensorimotor processing. Although the cerebellum has been proposed as a candidate for implementation of internal models, concrete evidence from neural responses is lacking. Here we exploit un-natural motion stimuli, which induce incorrect self-motion perception and eye movements, to explore the neural correlates of an internal model proposed to compensate for Einstein’s equivalence principle and generate neural estimates of linear acceleration and gravity. We show that caudal cerebellar vermis Purkinje cells and cerebellar nuclei neurons selective for actual linear acceleration also encode erroneous linear acceleration, as expected from the internal model hypothesis, even when no actual linear acceleration occurs. These findings provide strong evidence that the cerebellum might be involved in the implementation of internal models that mimic physical principles to interpret sensory signals, as previously hypothesized by theorists. PMID:24077562

Design of Linear Accelerator (LINAC) tanks for proton therapy via Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) approaches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castellano, T.; De Palma, L.; Laneve, D.

2015-07-01

A homemade computer code for designing a Side- Coupled Linear Accelerator (SCL) is written. It integrates a simplified model of SCL tanks with the Particle Swarm Optimization (PSO) algorithm. The computer code main aim is to obtain useful guidelines for the design of Linear Accelerator (LINAC) resonant cavities. The design procedure, assisted via the aforesaid approach seems very promising, allowing future improvements towards the optimization of actual accelerating geometries. (authors)

Investigation of Ion Beam Production and Acceleration Using Linear Electron Beams and a Pulse Powered Plasma Focus.

DTIC Science & Technology

1984-03-01

POWERED PLASMA FOCUS Contract No. AFOSR-83-0145 PROGRESS REPORT For the Period April 1, 1983 through March 31, 1984 Submitted to Air Force Office of...AND ACCELERATION USING LINEAR ELECTRON BEAMS AND A PULSE POWERED PLASMA FOCUS Contract No. AFOSR-83-0145 PROGRESS REPORT For the Period April 1, 1983...Acceleration Using Linear Electron Beams and a Pulse Powered Plasma Focus " 01 €,G APRIL 1, 1983 THROUGH MRCH 31, 1984 A. Collective Acceleration and Related

A coarse-grid projection method for accelerating incompressible flow computations

NASA Astrophysics Data System (ADS)

San, Omer; Staples, Anne

2011-11-01

We present a coarse-grid projection (CGP) algorithm for accelerating incompressible flow computations, which is applicable to methods involving Poisson equations as incompressibility constraints. CGP methodology is a modular approach that facilitates data transfer with simple interpolations and uses black-box solvers for the Poisson and advection-diffusion equations in the flow solver. Here, we investigate a particular CGP method for the vorticity-stream function formulation that uses the full weighting operation for mapping from fine to coarse grids, the third-order Runge-Kutta method for time stepping, and finite differences for the spatial discretization. After solving the Poisson equation on a coarsened grid, bilinear interpolation is used to obtain the fine data for consequent time stepping on the full grid. We compute several benchmark flows: the Taylor-Green vortex, a vortex pair merging, a double shear layer, decaying turbulence and the Taylor-Green vortex on a distorted grid. In all cases we use either FFT-based or V-cycle multigrid linear-cost Poisson solvers. Reducing the number of degrees of freedom of the Poisson solver by powers of two accelerates these computations while, for the first level of coarsening, retaining the same level of accuracy in the fine resolution vorticity field.

The Rim Inertial Measuring System (RIMS). [to measure angular rate and linear acceleration of a moving vehicle

NASA Technical Reports Server (NTRS)

Groom, N. J.

1979-01-01

The rim inertial measuring system (RIMS) is introduced and an approach for extracting angular rate and linear acceleration information from a RIMS unit is presented and discussed. The RIMS consists of one or more small annular momentum control devices (AMCDs), mounted in a strapped down configuration, which are used to measure angular rates and linear accelerations of a moving vehicle. An AMCD consists of a spinning rim, a set of noncontacting magnetic bearings for supporting the rim, and a noncontacting electromagnetic spin motor. The approach for extracting angular rate and linear acceleration information is for a single spacecraft mounted RIMS unit.

Electron linear accelerator system for natural rubber vulcanization

NASA Astrophysics Data System (ADS)

Rimjaem, S.; Kongmon, E.; Rhodes, M. W.; Saisut, J.; Thongbai, C.

2017-09-01

Development of an electron accelerator system, beam diagnostic instruments, an irradiation apparatus and electron beam processing methodology for natural rubber vulcanization is underway at the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The project is carried out with the aims to improve the qualities of natural rubber products. The system consists of a DC thermionic electron gun, 5-cell standing-wave radio-frequency (RF) linear accelerator (linac) with side-coupling cavities and an electron beam irradiation apparatus. This system is used to produce electron beams with an adjustable energy between 0.5 and 4 MeV and a pulse current of 10-100 mA at a pulse repetition rate of 20-400 Hz. An average absorbed dose between 160 and 640 Gy is expected to be archived for 4 MeV electron beam when the accelerator is operated at 400 Hz. The research activities focus firstly on assembling of the accelerator system, study on accelerator properties and electron beam dynamic simulations. The resonant frequency of the RF linac in π/2 operating mode is 2996.82 MHz for the operating temperature of 35 °C. The beam dynamic simulations were conducted by using the code ASTRA. Simulation results suggest that electron beams with an average energy of 4.002 MeV can be obtained when the linac accelerating gradient is 41.7 MV/m. The rms transverse beam size and normalized rms transverse emittance at the linac exit are 0.91 mm and 10.48 π mm·mrad, respectively. This information can then be used as the input data for Monte Carlo simulations to estimate the electron beam penetration depth and dose distribution in the natural rubber latex. The study results from this research will be used to define optimal conditions for natural rubber vulcanization with different electron beam energies and doses. This is very useful for development of future practical industrial accelerator units.

MABE multibeam accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasti, D.E.; Ramirez, J.J.; Coleman, P.D.

1985-01-01

The Megamp Accelerator and Beam Experiment (MABE) was the technology development testbed for the multiple beam, linear induction accelerator approach for Hermes III, a new 20 MeV, 0.8 MA, 40 ns accelerator being developed at Sandia for gamma-ray simulation. Experimental studies of a high-current, single-beam accelerator (8 MeV, 80 kA), and a nine-beam injector (1.4 MeV, 25 kA/beam) have been completed, and experiments on a nine-beam linear induction accelerator are in progress. A two-beam linear induction accelerator is designed and will be built as a gamma-ray simulator to be used in parallel with Hermes III. The MABE pulsed power systemmore » and accelerator for the multiple beam experiments is described. Results from these experiments and the two-beam design are discussed. 11 refs., 6 figs.« less

Accelerator Science: Circular vs. Linear

ScienceCinema

Lincoln, Don

2018-06-12

Particle accelerator are scientific instruments that allow scientists to collide particles together at incredible energies to study the secrets of the universe. However, there are many manners in which particle accelerators can be constructed. In this video, Fermilab’s Dr. Don Lincoln explains the pros and cons of circular and linear accelerators.

Experimental evidence of space charge driven resonances in high intensity linear accelerators

DOE PAGES

Jeon, Dong -O

2016-01-12

In the construction of high intensity accelerators, it is the utmost goal to minimize the beam loss by avoiding or minimizing contributions of various halo formation mechanisms. As a halo formation mechanism, space charge driven resonances are well known for circular accelerators. However, the recent finding showed that even in linear accelerators the space charge potential can excite the 4σ = 360° fourth order resonance [D. Jeon et al., Phys. Rev. ST Accel. Beams 12, 054204 (2009)]. This study increased the interests in space charge driven resonances of linear accelerators. Experimental studies of the space charge driven resonances of highmore » intensity linear accelerators are rare as opposed to the multitude of simulation studies. This paper presents an experimental evidence of the space charge driven 4σ ¼ 360° resonance and the 2σ x(y) – 2σ z = 0 resonance of a high intensity linear accelerator through beam profile measurements from multiple wire-scanners. Moreover, measured beam profiles agree well with the characteristics of the space charge driven 4σ = 360° resonance and the 2σ x(y) – 2σ z = 0 resonance that are predicted by the simulation.« less

Ion Motion Induced Emittance Growth of Matched Electron Beams in Plasma Wakefields

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, Weiming; Lu, Wei; Huang, Chengkun

2017-06-14

Plasma-based acceleration is being considered as the basis for building a future linear collider. Nonlinear plasma wakefields have ideal properties for accelerating and focusing electron beams. Preservation of the emittance of nano-Coulomb beams with nanometer scale matched spot sizes in these wakefields remains a critical issue due to ion motion caused by their large space charge forces. We use fully resolved quasistatic particle-in-cell simulations of electron beams in hydrogen and lithium plasmas, including when the accelerated beam has different emittances in the two transverse planes. The projected emittance initially grows and rapidly saturates with a maximum emittance growth of lessmore » than 80% in hydrogen and 20% in lithium. The use of overfocused beams is found to dramatically reduce the emittance growth. In conclusion, the underlying physics that leads to the lower than expected emittance growth is elucidated.« less

Intern Programs | Tours

Science.gov Websites

accelerated through the Linac (Linear Accelerator) to an energy of 400 MeV. The Linac consists of two main of linear accelerators at NML ! Meet at the South entrance to NML (New Muon Lab) Building. 1:00 PM 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hogan, Mark

Plasma wakefield acceleration has the potential to dramatically shrink the size and cost of particle accelerators. Research at the SLAC National Accelerator Laboratory has demonstrated that plasmas can provide 1,000 times the acceleration in a given distance compared with current technologies. Developing revolutionary and more efficient acceleration techniques that allow for an affordable high-energy collider is the focus of FACET, a National User Facility at SLAC. The existing FACET National User Facility uses part of SLAC’s two-mile-long linear accelerator to generate high-density beams of electrons and positrons. FACET-II is a new test facility to develop advanced acceleration and coherent radiationmore » techniques with high-energy electron and positron beams. It is the only facility in the world with high energy positron beams. FACET-II provides a major upgrade over current FACET capabilities and the breadth of the potential research program makes it truly unique. It will synergistically pursue accelerator science that is vital to the future of both advanced acceleration techniques for High Energy Physics, ultra-high brightness beams for Basic Energy Science, and novel radiation sources for a wide variety of applications. The design parameters for FACET-II are set by the requirements of the plasma wakefield experimental program. To drive the plasma wakefield requires a high peak current, in excess of 10kA. To reach this peak current, the electron and positron design bunch size is 10μ by 10μ transversely with a bunch length of 10μ. This is more than 200 times better than what has been achieved at the existing FACET. The beam energy is 10 GeV, set by the Linac length available and the repetition rate is up to 30 Hz. The FACET-II project is scheduled to be constructed in three major stages. Components of the project discussed in detail include the following: electron injector, bunch compressors and linac, the positron system, the Sector 20 sailboat and W chicanes, and experimental area and infrastructure.« less

Perception of linear acceleration in weightlessness

NASA Technical Reports Server (NTRS)

Arrott, A. P.; Young, L. R.

1987-01-01

Eye movements and subjective detection of acceleration were measured on human experimental subjects during vestibular sled acceleration during the D1 Spacelab Mission. Methods and results are reported on the time to detection of small acceleration steps, the threshold for detection of linear acceleration, perceived motion path, and CLOAT. A consistently shorter time to detection of small acceleration steps is found. Subjective reports of perceived motion during sinusoidal oscillation in weightlessness were qualitatively similar to reports on earth.

Evaluating activation of the shielding walls of a treatment room using the Monte Carlo method

NASA Astrophysics Data System (ADS)

Lee, D.-Y.; Kim, J.-H.

2018-05-01

This study investigates the radiation activation process in a medical linear accelerator, which creates a photon beam with the energy acquired from accelerated electrons. The concrete shielding walls used in conjunction with a medical linear accelerator occupy the largest portion of facility decommissioning costs. Therefore, to evaluate the activation of the shielding wall, this study simulated the operation of a linear accelerator with high-energy photon beams (10, 15, and 20 MV). The results of the simulations showed that the high-energy photon beams produced a large number of neutrons in the areas around the linear accelerator head. Several radionuclides were identified, and their half-lives and radioactivity levels were calculated. Half-lives ranged from 2.62 hours to 3.68E+06 years, and the radioactivity levels of most of the radionuclides were found to satisfy their respective clearance requirements. These results indicate that photon beams of 15 MV or lower satisfy the clearance requirements for decommissioning a linear accelerator facility, whereas those of 20 MV or higher lie partially above the regulatory clearance levels.

Linear Motor With Air Slide

NASA Technical Reports Server (NTRS)

Johnson, Bruce G.; Gerver, Michael J.; Hawkey, Timothy J.; Fenn, Ralph C.

1993-01-01

Improved linear actuator comprises air slide and linear electric motor. Unit exhibits low friction, low backlash, and more nearly even acceleration. Used in machinery in which positions, velocities, and accelerations must be carefully controlled and/or vibrations must be suppressed.

Intraoperative radiation therapy using mobile electron linear accelerators: report of AAPM Radiation Therapy Committee Task Group No. 72.

PubMed

Beddar, A Sam; Biggs, Peter J; Chang, Sha; Ezzell, Gary A; Faddegon, Bruce A; Hensley, Frank W; Mills, Michael D

2006-05-01

Intraoperative radiation therapy (IORT) has been customarily performed either in a shielded operating suite located in the operating room (OR) or in a shielded treatment room located within the Department of Radiation Oncology. In both cases, this cancer treatment modality uses stationary linear accelerators. With the development of new technology, mobile linear accelerators have recently become available for IORT. Mobility offers flexibility in treatment location and is leading to a renewed interest in IORT. These mobile accelerator units, which can be transported any day of use to almost any location within a hospital setting, are assembled in a nondedicated environment and used to deliver IORT. Numerous aspects of the design of these new units differ from that of conventional linear accelerators. The scope of this Task Group (TG-72) will focus on items that particularly apply to mobile IORT electron systems. More specifically, the charges to this Task Group are to (i) identify the key differences between stationary and mobile electron linear accelerators used for IORT, (ii) describe and recommend the implementation of an IORT program within the OR environment, (iii) present and discuss radiation protection issues and consequences of working within a nondedicated radiotherapy environment, (iv) describe and recommend the acceptance and machine commissioning of items that are specific to mobile electron linear accelerators, and (v) design and recommend an efficient quality assurance program for mobile systems.

Feasibility study for mega-electron-volt electron beam tomography.

PubMed

Hampel, U; Bärtling, Y; Hoppe, D; Kuksanov, N; Fadeev, S; Salimov, R

2012-09-01

Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

ON THE PROBLEM OF PARTICLE GROUPINGS IN A TRAVELING WAVE LINEAR ACCELERATOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhileyko, G.I.

1957-01-01

A linear accelerator with traveling'' waves may be used for the production of especially short electron momenta, although in many cases the grouping capacity of the accelerator is not sufficient. Theoretically the case is derived in which grouping of the electrons takes place in the accelerator itself. (With 3 illustrations and 1 Slavic Reference). (TCO)

What Will the Neighbors Think? Building Large-Scale Science Projects Around the World

ScienceCinema

Jones, Craig; Mrotzek, Christian; Toge, Nobu; Sarno, Doug

2017-12-22

Public participation is an essential ingredient for turning the International Linear Collider into a reality. Wherever the proposed particle accelerator is sited in the world, its neighbors -- in any country -- will have something to say about hosting a 35-kilometer-long collider in their backyards. When it comes to building large-scale physics projects, almost every laboratory has a story to tell. Three case studies from Japan, Germany and the US will be presented to examine how community relations are handled in different parts of the world. How do particle physics laboratories interact with their local communities? How do neighbors react to building large-scale projects in each region? How can the lessons learned from past experiences help in building the next big project? These and other questions will be discussed to engage the audience in an active dialogue about how a large-scale project like the ILC can be a good neighbor.

Acceleration of incremental-pressure-correction incompressible flow computations using a coarse-grid projection method

NASA Astrophysics Data System (ADS)

Kashefi, Ali; Staples, Anne

2016-11-01

Coarse grid projection (CGP) methodology is a novel multigrid method for systems involving decoupled nonlinear evolution equations and linear elliptic equations. The nonlinear equations are solved on a fine grid and the linear equations are solved on a corresponding coarsened grid. Mapping functions transfer data between the two grids. Here we propose a version of CGP for incompressible flow computations using incremental pressure correction methods, called IFEi-CGP (implicit-time-integration, finite-element, incremental coarse grid projection). Incremental pressure correction schemes solve Poisson's equation for an intermediate variable and not the pressure itself. This fact contributes to IFEi-CGP's efficiency in two ways. First, IFEi-CGP preserves the velocity field accuracy even for a high level of pressure field grid coarsening and thus significant speedup is achieved. Second, because incremental schemes reduce the errors that arise from boundaries with artificial homogenous Neumann conditions, CGP generates undamped flows for simulations with velocity Dirichlet boundary conditions. Comparisons of the data accuracy and CPU times for the incremental-CGP versus non-incremental-CGP computations are presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westerly, D.

Experimental research in medical physics has expanded the limits of our knowledge and provided novel imaging and therapy technologies for patients around the world. However, experimental efforts are challenging due to constraints in funding, space, time and other forms of institutional support. In this joint ESTRO-AAPM symposium, four exciting experimental projects from four different countries are highlighted. Each project is focused on a different aspect of radiation therapy. From the USA, we will hear about a new linear accelerator concept for more compact and efficient therapy devices. From Canada, we will learn about novel linear accelerator target design and themore » implications for imaging and therapy. From France, we will discover a mature translational effort to incorporate theranostic nanoparticles in MR-guided radiation therapy. From Germany, we will find out about a novel in-treatment imaging modality for particle therapy. These examples of high impact, experimental medical physics research are representative of the diversity of such efforts that are on-going around the globe. J. Robar, Research is supported through collaboration with Varian Medical Systems and Brainlab AGD. Westerly, This work is supported by the Department of Radiation Oncology at the University of Colorado School of Medicine. COI: NONEK. Parodi, Part of the presented work is supported by the DFG (German Research Foundation) Cluster of Excellence MAP (Munich-Centre for Advanced Photonics) and has been carried out in collaboration with IBA.« less

MO-FG-BRC-04: Ionacoustic Imaging for Particle Range Verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parodi, K.

2016-06-15

Experimental research in medical physics has expanded the limits of our knowledge and provided novel imaging and therapy technologies for patients around the world. However, experimental efforts are challenging due to constraints in funding, space, time and other forms of institutional support. In this joint ESTRO-AAPM symposium, four exciting experimental projects from four different countries are highlighted. Each project is focused on a different aspect of radiation therapy. From the USA, we will hear about a new linear accelerator concept for more compact and efficient therapy devices. From Canada, we will learn about novel linear accelerator target design and themore » implications for imaging and therapy. From France, we will discover a mature translational effort to incorporate theranostic nanoparticles in MR-guided radiation therapy. From Germany, we will find out about a novel in-treatment imaging modality for particle therapy. These examples of high impact, experimental medical physics research are representative of the diversity of such efforts that are on-going around the globe. J. Robar, Research is supported through collaboration with Varian Medical Systems and Brainlab AGD. Westerly, This work is supported by the Department of Radiation Oncology at the University of Colorado School of Medicine. COI: NONEK. Parodi, Part of the presented work is supported by the DFG (German Research Foundation) Cluster of Excellence MAP (Munich-Centre for Advanced Photonics) and has been carried out in collaboration with IBA.« less

LINEAR ACCELERATOR

DOEpatents

Christofilos, N.C.; Polk, I.J.

1959-02-17

Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.

Non-perturbative aspects of particle acceleration in non-linear electrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burton, David A.; Flood, Stephen P.; Wen, Haibao

2015-04-15

We undertake an investigation of particle acceleration in the context of non-linear electrodynamics. We deduce the maximum energy that an electron can gain in a non-linear density wave in a magnetised plasma, and we show that an electron can “surf” a sufficiently intense Born-Infeld electromagnetic plane wave and be strongly accelerated by the wave. The first result is valid for a large class of physically reasonable modifications of the linear Maxwell equations, whilst the second result exploits the special mathematical structure of Born-Infeld theory.

Detecting chaos in particle accelerators through the frequency map analysis method.

PubMed

Papaphilippou, Yannis

2014-06-01

The motion of beams in particle accelerators is dominated by a plethora of non-linear effects, which can enhance chaotic motion and limit their performance. The application of advanced non-linear dynamics methods for detecting and correcting these effects and thereby increasing the region of beam stability plays an essential role during the accelerator design phase but also their operation. After describing the nature of non-linear effects and their impact on performance parameters of different particle accelerator categories, the theory of non-linear particle motion is outlined. The recent developments on the methods employed for the analysis of chaotic beam motion are detailed. In particular, the ability of the frequency map analysis method to detect chaotic motion and guide the correction of non-linear effects is demonstrated in particle tracking simulations but also experimental data.

Wireless acceleration sensor of moving elements for condition monitoring of mechanisms

NASA Astrophysics Data System (ADS)

Sinitsin, Vladimir V.; Shestakov, Aleksandr L.

2017-09-01

Comprehensive analysis of the angular and linear accelerations of moving elements (shafts, gears) allows an increase in the quality of the condition monitoring of mechanisms. However, existing tools and methods measure either linear or angular acceleration with postprocessing. This paper suggests a new construction design of an angular acceleration sensor for moving elements. The sensor is mounted on a moving element and, among other things, the data transfer and electric power supply are carried out wirelessly. In addition, the authors introduce a method for processing the received information which makes it possible to divide the measured acceleration into the angular and linear components. The design has been validated by the results of laboratory tests of an experimental model of the sensor. The study has shown that this method provides a definite separation of the measured acceleration into linear and angular components, even in noise. This research contributes an advance in the range of methods and tools for condition monitoring of mechanisms.

SU-E-T-543: Measurement of Neutron Activation From Different High Energy Varian Linear Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thatcher, T; Madsen, S; Sudowe, R

2015-06-15

Purpose: Linear accelerators producing photons above 10 MeV may induce photonuclear reactions in high Z components of the accelerator. These liberated neutrons can then activate the structural components of the accelerator and other materials in the beam path through neutron capture reactions. The induced activity within the accelerator may contribute to additional dose to both patients and personnel. This project seeks to determine the total activity and activity per activated isotope following irradiation in different Varian accelerators at energies above 10 MeV. Methods: A Varian 21IX accelerator was used to irradiate a 30 cm × 30 cm × 20 cmmore » solid water phantom with 15 MV x-rays. The phantom was placed at an SSD of 100 cm and at the center of a 20 cm × 20 cm field. Activation induced gamma spectra were acquired over a 5 minute interval after 1 and 15 minutes from completion of the irradiation. All measurements were made using a CANBERRA Falcon 5000 Portable HPGe detector. The majority of measurements were made in scattering geometry with the detector situated at 90° to the incident beam, 30 cm from the side of the phantom and approximately 10 cm from the top. A 5 minute background count was acquired and automatically subtracted from all subsequent measurements. Photon spectra were acquired for both open and MLC fields. Results: Based on spectral signatures, nuclides have been identified and their activities calculated for both open and MLC fields. Preliminary analyses suggest that activities from the activation products in the microcurie range. Conclusion: Activation isotopes have been identified and their relative activities determined. These activities are only gross estimates since efficiencies have not been determined for this source-detector geometry. Current efforts are focused on accurate determination of detector efficiencies using Monte Carlo calculations.« less

Development of a 20 MeV Dielectric-Loaded Test Accelerator

NASA Astrophysics Data System (ADS)

Gold, Steven H.; Kinkead, Allen K.; Gai, Wei; Power, John G.; Konecny, Richard; Jing, Chunguang; Long, Jidong; Tantawi, Sami G.; Nantista, Christopher D.; Bruce, Ralph W.; Fliflet, Arne W.; Lombardi, Marcie; Lewis, David

2006-11-01

This paper presents a progress report on a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded test accelerator in the magnicon facility at NRL. The accelerator will be powered by an experimental 11.424-GHz magnicon amplifier that presently produces 25 MW of output power in a ˜250-ns pulse at up to 10 Hz. The accelerator will include a 5-MeV electron injector originally developed at the Tsinghua University in Beijing, China, and can incorporate DLA structures up to 0.5 m in length. The DLA structures are being developed by ANL, and shorter test structures fabricated from a variety of dielectric materials have undergone testing at NRL at gradients up to ˜8 MV/m. SLAC has developed components to distribute the power from the two magnicon output arms to the injector and to the DLA accelerating structure with separate control of the power ratio and relative phase. RWBruce Associates, Inc., working with NRL, has investigated means to join short ceramic sections into a continuous accelerator tube by a brazing process using an intense 83-GHz beam. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA test structure, and spectrometer, should take place within the next year.

GPU-based Branchless Distance-Driven Projection and Backprojection

PubMed Central

Liu, Rui; Fu, Lin; De Man, Bruno; Yu, Hengyong

2017-01-01

Projection and backprojection operations are essential in a variety of image reconstruction and physical correction algorithms in CT. The distance-driven (DD) projection and backprojection are widely used for their highly sequential memory access pattern and low arithmetic cost. However, a typical DD implementation has an inner loop that adjusts the calculation depending on the relative position between voxel and detector cell boundaries. The irregularity of the branch behavior makes it inefficient to be implemented on massively parallel computing devices such as graphics processing units (GPUs). Such irregular branch behaviors can be eliminated by factorizing the DD operation as three branchless steps: integration, linear interpolation, and differentiation, all of which are highly amenable to massive vectorization. In this paper, we implement and evaluate a highly parallel branchless DD algorithm for 3D cone beam CT. The algorithm utilizes the texture memory and hardware interpolation on GPUs to achieve fast computational speed. The developed branchless DD algorithm achieved 137-fold speedup for forward projection and 188-fold speedup for backprojection relative to a single-thread CPU implementation. Compared with a state-of-the-art 32-thread CPU implementation, the proposed branchless DD achieved 8-fold acceleration for forward projection and 10-fold acceleration for backprojection. GPU based branchless DD method was evaluated by iterative reconstruction algorithms with both simulation and real datasets. It obtained visually identical images as the CPU reference algorithm. PMID:29333480

GPU-based Branchless Distance-Driven Projection and Backprojection.

PubMed

Liu, Rui; Fu, Lin; De Man, Bruno; Yu, Hengyong

2017-12-01

Projection and backprojection operations are essential in a variety of image reconstruction and physical correction algorithms in CT. The distance-driven (DD) projection and backprojection are widely used for their highly sequential memory access pattern and low arithmetic cost. However, a typical DD implementation has an inner loop that adjusts the calculation depending on the relative position between voxel and detector cell boundaries. The irregularity of the branch behavior makes it inefficient to be implemented on massively parallel computing devices such as graphics processing units (GPUs). Such irregular branch behaviors can be eliminated by factorizing the DD operation as three branchless steps: integration, linear interpolation, and differentiation, all of which are highly amenable to massive vectorization. In this paper, we implement and evaluate a highly parallel branchless DD algorithm for 3D cone beam CT. The algorithm utilizes the texture memory and hardware interpolation on GPUs to achieve fast computational speed. The developed branchless DD algorithm achieved 137-fold speedup for forward projection and 188-fold speedup for backprojection relative to a single-thread CPU implementation. Compared with a state-of-the-art 32-thread CPU implementation, the proposed branchless DD achieved 8-fold acceleration for forward projection and 10-fold acceleration for backprojection. GPU based branchless DD method was evaluated by iterative reconstruction algorithms with both simulation and real datasets. It obtained visually identical images as the CPU reference algorithm.

1985 Particle Accelerator Conference: Accelerator Engineering and Technology, 11th, Vancouver, Canada, May 13-16, 1985, Proceedings

NASA Astrophysics Data System (ADS)

Strathdee, A.

1985-10-01

The topics discussed are related to high-energy accelerators and colliders, particle sources and electrostatic accelerators, controls, instrumentation and feedback, beam dynamics, low- and intermediate-energy circular accelerators and rings, RF and other acceleration systems, beam injection, extraction and transport, operations and safety, linear accelerators, applications of accelerators, radiation sources, superconducting supercolliders, new acceleration techniques, superconducting components, cryogenics, and vacuum. Accelerator and storage ring control systems are considered along with linear and nonlinear orbit theory, transverse and longitudinal instabilities and cures, beam cooling, injection and extraction orbit theory, high current dynamics, general beam dynamics, and medical and radioisotope applications. Attention is given to superconducting RF structures, magnet technology, superconducting magnets, and physics opportunities with relativistic heavy ion accelerators.

Design and Analysis of Megawatt Class Free Electron Laser Weapons

DTIC Science & Technology

2015-12-01

accelerating structure. The SRF linear accelerator stores RF fields within its niobium cavities. Superconductors require less average RF power than...is needed to cool the superconductor for the SRF linear accelerator. A current outstanding research topic is the RF frequency to use for the SRF

Superconducting six-axis accelerometer

NASA Technical Reports Server (NTRS)

Paik, H. J.

1990-01-01

A new superconducting accelerometer, capable of measuring both linear and angular accelerations, is under development at the University of Maryland. A single superconducting proof mass is magnetically levitated against gravity or any other proof force. Its relative positions and orientations with respect to the platform are monitored by six superconducting inductance bridges sharing a single amplifier, called the Superconducting Quantum Interference Device (SQUID). The six degrees of freedom, the three linear acceleration components and the three angular acceleration components, of the platform are measured simultaneously. In order to improve the linearity and the dynamic range of the instrument, the demodulated outputs of the SQUID are fed back to appropriate levitation coils so that the proof mass remains at the null position for all six inductance bridges. The expected intrinsic noise of the instrument is 4 x 10(exp -12)m s(exp -2) Hz(exp -1/2) for linear acceleration and 3 x 10(exp -11) rad s(exp -2) Hz(exp -1/2) for angular acceleration in 1-g environment. In 0-g, the linear acceleration sensitivity of the superconducting accelerometer could be improved by two orders of magnitude. The design and the operating principle of a laboratory prototype of the new instrument is discussed.

Coupling and decoupling of the accelerating units for pulsed synchronous linear accelerator

NASA Astrophysics Data System (ADS)

Shen, Yi; Liu, Yi; Ye, Mao; Zhang, Huang; Wang, Wei; Xia, Liansheng; Wang, Zhiwen; Yang, Chao; Shi, Jinshui; Zhang, Linwen; Deng, Jianjun

2017-12-01

A pulsed synchronous linear accelerator (PSLA), based on the solid-state pulse forming line, photoconductive semiconductor switch, and high gradient insulator technologies, is a novel linear accelerator. During the prototype PSLA commissioning, the energy gain of proton beams was found to be much lower than expected. In this paper, the degradation of the energy gain is explained by the circuit and cavity coupling effect of the accelerating units. The coupling effects of accelerating units are studied, and the circuit topologies of these two kinds of coupling effects are presented. Two methods utilizing inductance and membrane isolations, respectively, are proposed to reduce the circuit coupling effects. The effectiveness of the membrane isolation method is also supported by simulations. The decoupling efficiency of the metal drift tube is also researched. We carried out the experiments on circuit decoupling of the multiple accelerating cavity. The result shows that both circuit decoupling methods could increase the normalized voltage.

Cast dielectric composite linear accelerator

DOEpatents

Sanders, David M [Livermore, CA; Sampayan, Stephen [Manteca, CA; Slenes, Kirk [Albuquerque, NM; Stoller, H M [Albuquerque, NM

2009-11-10

A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

Development of high resolution linear-cut beam position monitor for heavy-ion synchrotron of KHIMA project

NASA Astrophysics Data System (ADS)

Hwang, Ji-Gwang; Yang, Tae-Keun; Forck, Peter; Noh, Seon Yeong; Hahn, Garam; Choi, Minkyoo

2017-04-01

A beam position monitor with high precision and resolution is required to control the beam trajectory for matching to the injection orbit and acceleration in a heavy-ion synchrotron. It will be also used for measuring the beta function, tune, and chromaticity. Since the bunch length at heavy ion synchrotron is relatively long, a few meters, a boxlike device with plates of typically 20 cm length is used to enhance the signal strength and to get a precise linear dependence with respect to the beam displacement. Especially, the linear-cut beam position monitor is adopted to satisfy the position resolution of 100 μm and accuracy of 200 μm for a nominal beam intensity in the KHIMA synchrotron of ∼ 7 ×108 particles for the carbon beams and ∼ 2 ×1010 for the proton beams. In this paper, we show the electromagnetic design of the electrode and surroundings to satisfy the resolution of 100 μm, the criteria for mechanical aspect to satisfy the position accuracy of 200 μm, the measurement results by using wire test-bench, design and measurement of a high input impedance pre-amplifier, and the beam-test results with long (∼1.6 μs) electron beam in Pohang accelerator laboratory (PAL).

A scientific and statistical analysis of accelerated aging for pharmaceuticals. Part 1: accuracy of fitting methods.

PubMed

Waterman, Kenneth C; Swanson, Jon T; Lippold, Blake L

2014-10-01

Three competing mathematical fitting models (a point-by-point estimation method, a linear fit method, and an isoconversion method) of chemical stability (related substance growth) when using high temperature data to predict room temperature shelf-life were employed in a detailed comparison. In each case, complex degradant formation behavior was analyzed by both exponential and linear forms of the Arrhenius equation. A hypothetical reaction was used where a drug (A) degrades to a primary degradant (B), which in turn degrades to a secondary degradation product (C). Calculated data with the fitting models were compared with the projected room-temperature shelf-lives of B and C, using one to four time points (in addition to the origin) for each of three accelerated temperatures. Isoconversion methods were found to provide more accurate estimates of shelf-life at ambient conditions. Of the methods for estimating isoconversion, bracketing the specification limit at each condition produced the best estimates and was considerably more accurate than when extrapolation was required. Good estimates of isoconversion produced similar shelf-life estimates fitting either linear or nonlinear forms of the Arrhenius equation, whereas poor isoconversion estimates favored one method or the other depending on which condition was most in error. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

A General Accelerated Degradation Model Based on the Wiener Process.

PubMed

Liu, Le; Li, Xiaoyang; Sun, Fuqiang; Wang, Ning

2016-12-06

Accelerated degradation testing (ADT) is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses.

A General Accelerated Degradation Model Based on the Wiener Process

PubMed Central

Liu, Le; Li, Xiaoyang; Sun, Fuqiang; Wang, Ning

2016-01-01

Accelerated degradation testing (ADT) is an efficient tool to conduct material service reliability and safety evaluations by analyzing performance degradation data. Traditional stochastic process models are mainly for linear or linearization degradation paths. However, those methods are not applicable for the situations where the degradation processes cannot be linearized. Hence, in this paper, a general ADT model based on the Wiener process is proposed to solve the problem for accelerated degradation data analysis. The general model can consider the unit-to-unit variation and temporal variation of the degradation process, and is suitable for both linear and nonlinear ADT analyses with single or multiple acceleration variables. The statistical inference is given to estimate the unknown parameters in both constant stress and step stress ADT. The simulation example and two real applications demonstrate that the proposed method can yield reliable lifetime evaluation results compared with the existing linear and time-scale transformation Wiener processes in both linear and nonlinear ADT analyses. PMID:28774107

Preliminary research concerning the use of electron accelerators to improve the conservability and to extend the shelf-life of fruits and vegetables

NASA Astrophysics Data System (ADS)

Minea, R.; Oproiu, C.; Pascanu, S.; Matei, C.; Ferdes, O.

1996-06-01

The potential of ionizing radiation treatment for food preservation, shelf-life extension, control of microbial load and reduction of pathogenic microorganism was demonstrated. The irradiations were performed under normal conditions on the Institute of Physics and Technology for Radiation Device's linear electron accelerator, which has the following parameters: 5 μA mean beam current, 6 MeV electron mean energy, pulse period 3.5 μs and dose rates between 100-1500 Gy/min. This research project was aimed at assuring the consumer's acceptance for radiation-treated food and to obtain a significant reduction of food losses. We also propose a promising solution for the radiation processing of some bulk food products at the place of storage, consisting of a mobile electron accelerator. The main characteristics of the mobile electron accelerator are: electron energy 3 to 5 MeV, maximum beam power 5 kW, vertical electron beam; irradiation is possible both with electron beams and with bremsstrahlung. The results of our preliminary research lead to the conclusion that electron-beam irradiation and the use of electron accelerators is a promising solution for food preservation and food safety. Interesting future applications are outlined.

A Linear Accelerator for TA-FD calibration

NASA Astrophysics Data System (ADS)

Shibata, T.; Ikeda, D.; Ikeda, M.; Enomoto, A.; Ohsawa, S.; Kakiha, K.; Kakihara, K.; Sagawa, H.; Satoh, M.; Shidara, T.; Sugimura, T.; Fukushima, M.; Fukuda, S.; Furukawa, K.; Yoshida, M.

The energy of the primary cosmic ray can be calculated from fluorescence photons detected by fluorescence telescope. However, since we can not know the true energy of primary cosmic ray, it is difficult to calibrate between number of photons and energy directly. In TA project, we will create pseudo- cosmic ray events by using accelerated electron beam which is injected in the air. The injected electron beam creates an air shower and fluorescence photons are emitted. We can calibate between electron beam energy which is known exactry and detected photons. We are developping a small linear accelerator (Linac) at High Energy Accelerator Research Organization (KEK) in Japan. The maximum energy is 40MeV, the typical current is 0.16nC, and the intensity per pulse is 6.4mJ. The accuracy of beam energy is less than 1%. The Linac consists of a -100kV pulse type electron gun, a 1.5m pre-buncher and buncher tube, a 2m S-band accelerator tube, a quadrupole magnet, a 90 degree bending magnet, and a S-Band(2856MHz) 50MW high power klystron as RF source. We chekced the performance of the electron beam, energy resolution, beam spread, beam current, and beam loss by PARMELA simulation, and checked the air shower by electron beam and number of the detected photons by detector simulation which are made by GEANT4. In this Spring, we will do the full beam test in KEK. The beam operation in Utah will be started from this Autumn. In this talk, we will report about the results of the beam test and calibration method by this Linac.

LINEAR LATTICE AND TRAJECTORY RECONSTRUCTION AND CORRECTION AT FAST LINEAR ACCELERATOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romanov, A.; Edstrom, D.; Halavanau, A.

2017-07-16

The low energy part of the FAST linear accelerator based on 1.3 GHz superconducting RF cavities was successfully commissioned [1]. During commissioning, beam based model dependent methods were used to correct linear lattice and trajectory. Lattice correction algorithm is based on analysis of beam shape from profile monitors and trajectory responses to dipole correctors. Trajectory responses to field gradient variations in quadrupoles and phase variations in superconducting RF cavities were used to correct bunch offsets in quadrupoles and accelerating cavities relative to their magnetic axes. Details of used methods and experimental results are presented.

A method for evaluating dynamical friction in linear ball bearings.

PubMed

Fujii, Yusaku; Maru, Koichi; Jin, Tao; Yupapin, Preecha P; Mitatha, Somsak

2010-01-01

A method is proposed for evaluating the dynamical friction of linear bearings, whose motion is not perfectly linear due to some play in its internal mechanism. In this method, the moving part of a linear bearing is made to move freely, and the force acting on the moving part is measured as the inertial force given by the product of its mass and the acceleration of its centre of gravity. To evaluate the acceleration of its centre of gravity, the acceleration of two different points on it is measured using a dual-axis optical interferometer.

Magnetic field errors tolerances of Nuclotron booster

NASA Astrophysics Data System (ADS)

Butenko, Andrey; Kazinova, Olha; Kostromin, Sergey; Mikhaylov, Vladimir; Tuzikov, Alexey; Khodzhibagiyan, Hamlet

2018-04-01

Generation of magnetic field in units of booster synchrotron for the NICA project is one of the most important conditions for getting the required parameters and qualitative accelerator operation. Research of linear and nonlinear dynamics of ion beam 197Au31+ in the booster have carried out with MADX program. Analytical estimation of magnetic field errors tolerance and numerical computation of dynamic aperture of booster DFO-magnetic lattice are presented. Closed orbit distortion with random errors of magnetic fields and errors in layout of booster units was evaluated.

The Ability of American Football Helmets to Manage Linear Acceleration With Repeated High-Energy Impacts.

PubMed

Cournoyer, Janie; Post, Andrew; Rousseau, Philippe; Hoshizaki, Blaine

2016-03-01

Football players can receive up to 1400 head impacts per season, averaging 6.3 impacts per practice and 14.3 impacts per game. A decrease in the capacity of a helmet to manage linear acceleration with multiple impacts could increase the risk of traumatic brain injury. To investigate the ability of football helmets to manage linear acceleration with multiple high-energy impacts. Descriptive laboratory study. Laboratory. We collected linear-acceleration data for 100 impacts at 6 locations on 4 helmets of different models currently used in football. Impacts 11 to 20 were compared with impacts 91 to 100 for each of the 6 locations. Linear acceleration was greater after multiple impacts (91-100) than after the first few impacts (11-20) for the front, front-boss, rear, and top locations. However, these differences are not clinically relevant as they do not affect the risk for head injury. American football helmet performance deteriorated with multiple impacts, but this is unlikely to be a factor in head-injury causation during a game or over a season.

Final Report, Next-Generation Mega-Voltage Cargo-Imaging System for Cargo Conainer Inspection, March 2007

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dr. James Clayton, Ph.D., Varian Medical Systems-Security & Inspection Products; Dr. Emma Regentova, Ph.D, University of Nevada Las Vegas; Dr. Evangelos Yfantis, Ph.D., University of Nevada, Las Vegas

The UNLV Research Foundation, as the primary award recipient, teamed with Varian Medical Systems-Security & Inspection Products and the University of Nevada Las Vegas (UNLV) for the purpose of conducting research and engineering related to a "next-generation" mega-voltage imaging (MVCI) system for inspection of cargo in large containers. The procurement and build-out of hardware for the MVCI project has been completed. The K-9 linear accelerator and an optimized X-ray detection system capable of efficiently detecting X-rays emitted from the accelerator after they have passed through the device is under test. The Office of Science financial assistance award has made possiblemore » the development of a system utilizing a technology which will have a profound positive impact on the security of U.S. seaports. The proposed project will ultimately result in critical research and development advances for the "next-generation" Linatron X-ray accelerator technology, thereby providing a safe, reliable and efficient fixed and mobile cargo inspection system, which will very significantly increase the fraction of cargo containers undergoing reliable inspection as the enter U.S. ports. Both NNSA/NA-22 and the Department of Homeland Security's Domestic Nuclear Detection Office are collaborating with UNLV and its team to make this technology available as soon as possible.« less

Applications of Electron Linear Induction Accelerators

NASA Astrophysics Data System (ADS)

Westenskow*, Glen; Chen, Yu-Jiuan

Linear Induction Accelerators (LIAs) can readily produce intense electron beams. For example, the ATA accelerator produced a 500 GW beam and the LIU-30 a 4 TW beam (see Chap. 2). Since the induction accelerator concept was proposed in the late 1950s [1, 2], there have been many proposed schemes to convert the beam power to other forms. Categories of applications that have been demonstrated for electron LIAs include:

Two Step Acceleration Process of Electrons in the Outer Van Allen Radiation Belt by Time Domain Electric Field Bursts and Large Amplitude Chorus Waves

NASA Astrophysics Data System (ADS)

Agapitov, O. V.; Mozer, F.; Artemyev, A.; Krasnoselskikh, V.; Lejosne, S.

2014-12-01

A huge number of different non-linear structures (double layers, electron holes, non-linear whistlers, etc) have been observed by the electric field experiment on the Van Allen Probes in conjunction with relativistic electron acceleration in the Earth's outer radiation belt. These structures, found as short duration (~0.1 msec) quasi-periodic bursts of electric field in the high time resolution electric field waveform, have been called Time Domain Structures (TDS). They can quite effectively interact with radiation belt electrons. Due to the trapping of electrons into these non-linear structures, they are accelerated up to ~10 keV and their pitch angles are changed, especially for low energies (˜1 keV). Large amplitude electric field perturbations cause non-linear resonant trapping of electrons into the effective potential of the TDS and these electrons are then accelerated in the non-homogeneous magnetic field. These locally accelerated electrons create the "seed population" of several keV electrons that can be accelerated by coherent, large amplitude, upper band whistler waves to MeV energies in this two step acceleration process. All the elements of this chain acceleration mechanism have been observed by the Van Allen Probes.

Respiratory motion guided four dimensional cone beam computed tomography: encompassing irregular breathing

NASA Astrophysics Data System (ADS)

O'Brien, Ricky T.; Cooper, Benjamin J.; Kipritidis, John; Shieh, Chun-Chien; Keall, Paul J.

2014-02-01

Four dimensional cone beam computed tomography (4DCBCT) images suffer from angular under sampling and bunching of projections due to a lack of feedback between the respiratory signal and the acquisition system. To address this problem, respiratory motion guided 4DCBCT (RMG-4DCBCT) regulates the gantry velocity and projection time interval, in response to the patient’s respiratory signal, with the aim of acquiring evenly spaced projections in a number of phase or displacement bins during the respiratory cycle. Our previous study of RMG-4DCBCT was limited to sinusoidal breathing traces. Here we expand on that work to provide a practical algorithm for the case of real patient breathing data. We give a complete description of RMG-4DCBCT including full details on how to implement the algorithms to determine when to move the gantry and when to acquire projections in response to the patient’s respiratory signal. We simulate a realistic working RMG-4DCBCT system using 112 breathing traces from 24 lung cancer patients. Acquisition used phase-based binning and parameter settings typically used on commercial 4DCBCT systems (4 min acquisition time, 1200 projections across 10 respiratory bins), with the acceleration and velocity constraints of current generation linear accelerators. We quantified streaking artefacts and image noise for conventional and RMG-4DCBCT methods by reconstructing projection data selected from an oversampled set of Catphan phantom projections. RMG-4DCBCT allows us to optimally trade-off image quality, acquisition time and image dose. For example, for the same image quality and acquisition time as conventional 4DCBCT approximately half the imaging dose is needed. Alternatively, for the same imaging dose, the image quality as measured by the signal to noise ratio, is improved by 63% on average. C-arm cone beam computed tomography systems, with an acceleration up to 200°/s2, a velocity up to 100°/s and the acquisition of 80 projections per second, allow the image acquisition time to be reduced to below 60 s. We have made considerable progress towards realizing a system to reduce projection clustering in conventional 4DCBCT imaging and hence reduce the imaging dose to the patient.

Status of the ATF Damping Ring BPM Upgrade Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Briegel, C.; /Fermilab; Eddy, N.

2011-12-01

A substantial upgrade of the beam position monitors (BPM) at the ATF (Accelerator Test Facility) damping ring is currently in progress. Implementing digital read-out signal processing techniques in line with an optimized, low-noise analog downconverter, a resolution well below 1 mum could be demonstrated at 20 (of 96) upgraded BPM stations. The narrowband, high resolution BPM mode permits investigation of all types of non-linearities, imperfections and other obstacles in the machine which may limit the very low target aimed vertical beam emittance of < 2 pm. The technical status of the project, first beam measurements and an outlook to it'smore » finalization are presented.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

ANDONIAN,G.BABZIEN,MLBEN-ZVI,I.YAKIMENKO,Y.ET AL.

VISA II is the follow-up project to the successful Visible to Infrared SASE Amplifier (VISA) experiment at the Accelerator Test Facility (ATF) in Brookhaven National Lab (BNL). This paper will report the motivation for and status of the two main experiments associated with the VISA II program. One goal of VISA II is to perform an experimental study of the physics of a chirped beam SASE FEL at the upgraded facilities of the ATF. This requires a linearization of the transport line to preserve energy chirping of the electron beam at injection. The other planned project is a strong bunchmore » compression experiment, where the electron bunch is compressed in the chicane, and the dispersive beamline transport, allowing studies of deep saturation.« less

Spatial correlation analysis of seismic noise for STAR X-ray infrastructure design

NASA Astrophysics Data System (ADS)

D'Alessandro, Antonino; Agostino, Raffaele; Festa, Lorenzo; Gervasi, Anna; Guerra, Ignazio; Palmer, Dennis T.; Serafini, Luca

2014-05-01

The Italian PON MaTeRiA project is focused on the creation of a research infrastructure open to users based on an innovative and evolutionary X-ray source. This source, named STAR (Southern Europe TBS for Applied Research), exploits the Thomson backscattering process of a laser radiation by fast-electron beams (Thomson Back Scattering - TBS). Its main performances are: X-ray photon flux 109-1010 ph/s, Angular divergence variable between 2 and 10 mrad, X-ray energy continuously variable between 8 keV and 150 keV, Bandwidth ΔE/E variable between 1 and 10%, ps time resolved structure. In order to achieve this performances, bunches of electrons produced by a photo-injector are accelerated to relativistic velocities by a linear accelerator section. The electron beam, few hundreds of micrometer wide, is driven by magnetic fields to the interaction point along a 15 m transport line where it is focused in a 10 micrometer-wide area. In the same area, the laser beam is focused after being transported along a 12 m structure. Ground vibrations could greatly affect the collision probability and thus the emittance by deviating the paths of the beams during their travel in the STAR source. Therefore, the study program to measure ground vibrations in the STAR site can be used for site characterization in relation to accelerator design. The environmental and facility noise may affect the X-ray operation especially if the predominant wavelengths in the microtremor wavefield are much smaller than the size of the linear accelerator. For wavelength much greater, all the accelerator parts move in phase, and therefore also large displacements cannot generate any significant effect. On the other hand, for wavelengths equal or less than half the accelerator size several parts could move in phase opposition and therefore small displacements could affect its proper functioning. Thereafter, it is important to characterize the microtremor wavefield in both frequencies and wavelengths domains. For this reason, we performed some measurements of seismic noise in order to characterize the environmental noise in the site in which the X-ray accelerator arise. For the characterization of the site, we carried out several passive seismic monitoring experiments at different times of the day and in different weather conditions. We recorded microtremor using an array of broadband 3C seismic sensors arranged along the linear accelerator. For each measurement point, we determined the displacement, velocity and acceleration spectrogram and power spectral density of both horizontal and vertical components. We determined also the microtremor horizontal to vertical spectral ratio as function of azimuth to individuate the main ground vibration direction and detect the existence of site or building resonance frequencies. We applied a rotation matrix to transform the North-South and East-West signal components in transversal and radial components, respect to the direction of the linear accelerator. Subsequently, for each couple of seismic stations we determined the coherence function to analyze the seismic noise spatial correlation. These analyses have allowed us to exhaustively characterize the seismic noise of the study area, from the point of view of the power and space-time variability, both in frequency and wavelength.

Amplitude-dependent orbital period in alternating gradient accelerators

DOE PAGES

Machida, S.; Kelliher, D. J.; Edmonds, C. S.; ...

2016-03-16

Orbital period in a ring accelerator and time of flight in a linear accelerator depend on the amplitude of betatron oscillations. The variation is negligible in ordinary particle accelerators with relatively small beam emittance. In an accelerator for large emittance beams like muons and unstable nuclei, however, this effect cannot be ignored. In this study, we measured orbital period in a linear non-scaling fixed-field alternating-gradient accelerator, which is a candidate for muon acceleration, and compared it with the theoretical prediction. The good agreement between them gives important ground for the design of particle accelerators for a new generation of particlemore » and nuclear physics experiments.« less

Instrumented mouthguard acceleration analyses for head impacts in amateur rugby union players over a season of matches.

PubMed

King, Doug; Hume, Patria A; Brughelli, Matt; Gissane, Conor

2015-03-01

Direct impacts with the head (linear acceleration or pressure) and inertial loading of the head (rotational acceleration or strain) have been postulated as the 2 major mechanisms of head-related injuries such as concussion. Although data are accumulating for soccer and American football, there are no published data for nonhelmeted collision sports such as rugby union. To quantify head impacts via instrumented mouthguard acceleration analyses for rugby union players over a season of matches. Descriptive epidemiology study. Data on impact magnitude and frequency were collected with molded instrumented mouthguards worn by 38 premier amateur senior rugby players participating in the 2013 domestic season of matches. A total of 20,687 impacts >10g (range, 10.0-164.9g) were recorded over the duration of the study. The mean ± SD number of impacts per player over the duration of the season of matches was 564 ± 618, resulting in a mean ± SD of 95 ± 133 impacts to the head per player, per match over the duration of the season of matches. The impact magnitudes for linear accelerations were skewed to the lower values (Sp = 3.7 ± 0.02; P < .001), with a mean linear acceleration of 22.2 ± 16.2g. Rotational accelerations were also skewed to the lower values (Sp = 2.0 ± 0.02; P < .001), with a mean rotational acceleration of 3902.9 ± 3948.8 rad/s(2). The acceleration magnitudes and number of head impacts in amateur rugby union players over a season of matches, measured via instrumented mouthguard accelerations, were higher than for most sports previously reported. Mean linear acceleration measured over a season of matches was similar to the mean linear accelerations previously reported for youth, high school, and collegiate American football players but lower than that for female youth soccer players. Mean rotational acceleration measured over a season of matches was similar to mean rotational accelerations for youth, high school, and collegiate American football players but less than those for female youth soccer players, concussed American collegiate players, collegiate American football players, and professional American football players. © 2014 The Author(s).

Dual linear accelerator system for use in sterilization of medical disposable supplies

NASA Astrophysics Data System (ADS)

Sadat, Theo

1991-05-01

Accelerators can be used for sterilization or decontamination (medical disposables, food, plastics, hospital waste, etc.). Most of these accelerators are located in an industrial environment and must have a high availability. A dual accelerator system (composed of two accelerators) offers optimal flexibility and reliability. The main advantage of this system is "all-in all-out" because it does not need a turnover of products. Such a dual system, composed of two 10 MeV 20 kW linear accelerators (instead of one 40 kW linac), has been chosen by a Swedish company (Mölnlycke).

The founding of CEBAF, 1979 to 1987

DOE Office of Scientific and Technical Information (OSTI.GOV)

C. Westfall

1995-02-01

In early 1979 a group of physicists assembled at the University of Virginia (UVa) for a conference entitled ''Future Possibilities for Electron Accelerators.'' In the audience sat an organizer of the conference, UVa professor James McCarthy. While listening to talks by Gregory Loew of the Stanford Linear Accelerator Center (SLAC) and Roger Servranckx of the University of Saskatchewan, McCarthy got very excited. Both discussed new approaches to producing an almost continuous stream of electrons with improved designs for pulse stretcher rings that could be built within a reasonable budget. McCarthy saw the possibility of realizing a dream. This dream hadmore » its origins in the 1950s, when Robert Hofstadter, McCarthy's thesis advisor, made groundbreaking discoveries at Stanford's High Energy Physics Laboratory (HEPL) about the internal structure of nuclei and nucleons. For these experiments Hofstadter used Mark III, the most advanced in a series of electron accelerators designed by William Hansen, who pioneered methods of high frequency acceleration of electrons. The work by Hofstadter and Hansen led to two productive lines of inquiry. One group of researchers studied particle production using electrons at higher energies, which led to the construction in the 1960s of SLAC at Stanford. Another group of researchers, which included McCarthy, investigated nuclear structure with more modest increases in energy accompanied by increases in the duty factor of the electron beam. This line of inquiry, electro-nuclear physics, led in the 1960s and 1970s to a succession of accelerators, including a $7.2 million high duty factor 400 MeV linear accelerator (linac) completed in 1972 at the Bates Laboratory at the Massachusetts Institute of Technology (Bates-MIT), and ambitious attempts to develop untried technologies to further boost energy and duty factor, most notably the effort to develop superconducting radiofrequency (srf) accelerating technology at HEPL. By 1979 electro-nuclear physics had attracted a considerable following. The growing electro-nuclear physics community was eager to find a scheme to permit virtually continuous acceleration, which would greatly improve the capability of performing coincidence experiments. In the words of the UVa conference proceedings, this experimental capability promised to open entire new areas of nuclear physics. Convinced that he could be the one to design the necessary groundbreaking machine after hearing the ideas of Loew and Servranckx, McCarthy began gathering a small accelerator building team. Against all odds, McCarthy's pipe dream resulted in the construction of a major accelerator laboratory, the Continuous Electron Beam Accelerator Facility (CEBAF). The founding of CEBAF is a tale of luck, perseverance, the triumph of flexible amateurism over rigid professionalism, and ironically, the potential of amateurs when supported by a thoroughly professional international network with well-defined methods for organizing and building accelerators. The CEBAF tale also has a surprise ending, for at the last minute, McCarthy's pipe dream was radically transformed by Hermann Grunder, who would direct the construction of the project. The twists and turns of this tale reveal many lessons about what aids and what detracts from the success of a large, federally sponsored scientific project.« less

High Power RF Testing of A 3-Cell Superconducting Traveling Wave Accelerating Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanareykin, Alex; Kostin, Romna; Avrakhov, Pavel

Euclid Techlabs has completed the Phase II SBIR project, entitled “High Power RF Testing of a 3-Cell Superconducting Traveling Wave Accelerating Structure” under Grant #DE-SC0006300. In this final technical report, we summarize the major achievements of Phase I of the project and review the details of Phase II of the project. The accelerating gradient in a superconducting structure is limited mainly by quenching, i.e., by the maximum surface RF magnetic field. Various techniques have been developed to increase the gradient. A traveling wave accelerating SC structure with a feedback waveguide was suggested to allow an increased transit time factor andmore » ultimately, a maximum gradient that is 22%-24% higher than in the best of the time standing wave SRF cavity solution. The proposed structure has an additional benefit in that it can be fabricated much longer than the standing wave ones that are limited by the field flatness factor. Taken together, all of these factors will result in a significant overall length and, correspondingly cost reduction of the SRF based linear collider ILC or SRF technology based FELs. In Phase I of this project, a 3-cell L-band SC traveling wave cavity was designed. Cavity shape, surface field ratios, inter-cell coupling coefficients, accelerating field flatness have been reviewed with the analysis of tuning issues. Moreover, the technological aspects of SC traveling wave accelerating structure fabrication have been studied. As the next step in the project, the Phase II experimental program included engineering design, manufacturing, surface processing and high gradient testing. Euclid Techlabs, LLC contracted AES, Inc. to manufacture two niobium cavities. Euclid Techlabs cold tested traveling wave regime in the cavity, and the results showed very good agreement with mathematical model specially developed for superconducting traveling wave cavity performance analysis. Traveling wave regime was adjusted by amplitude and phase variation of input signals due to application of developed power feeding scheme. Traveling wave excitation, adjustment and detection were successfully tested. Auxiliary equipment required for high power test such as the tuner, power and measure couplers, holding plates for VTS at Fermilab were developed and successfully tested. Both TW SRF cavities were fabricated by AES, Inc. without stiffening ribs before this company closed their production facility. Currently Roark EB welding company is finishing now welding process of the cavity for the high power testing at Fermilab VTS. Successful demonstration of high gradients in the 3-cell cavity along with studies of traveling wave excitation and tuning issues is leading to successful development of superconducting traveling wave technology for ILC applications and other future high energy SC accelerators.« less

Acceleration modules in linear induction accelerators

NASA Astrophysics Data System (ADS)

Wang, Shao-Heng; Deng, Jian-Jun

2014-05-01

The Linear Induction Accelerator (LIA) is a unique type of accelerator that is capable of accelerating kilo-Ampere charged particle current to tens of MeV energy. The present development of LIA in MHz bursting mode and the successful application into a synchrotron have broadened LIA's usage scope. Although the transformer model is widely used to explain the acceleration mechanism of LIAs, it is not appropriate to consider the induction electric field as the field which accelerates charged particles for many modern LIAs. We have examined the transition of the magnetic cores' functions during the LIA acceleration modules' evolution, distinguished transformer type and transmission line type LIA acceleration modules, and re-considered several related issues based on transmission line type LIA acceleration module. This clarified understanding should help in the further development and design of LIA acceleration modules.

Classical-trajectory simulation of accelerating neutral atoms with polarized intense laser pulses

NASA Astrophysics Data System (ADS)

Xia, Q. Z.; Fu, L. B.; Liu, J.

2013-03-01

In the present paper, we perform the classical trajectory Monte Carlo simulation of the complex dynamics of accelerating neutral atoms with linearly or circularly polarized intense laser pulses. Our simulations involve the ion motion as well as the tunneling ionization and the scattering dynamics of valence electron in the combined Coulomb and electromagnetic fields, for both helium (He) and magnesium (Mg). We show that for He atoms, only linearly polarized lasers can effectively accelerate the atoms, while for Mg atoms, we find that both linearly and circularly polarized lasers can successively accelerate the atoms. The underlying mechanism is discussed and the subcycle dynamics of accelerating trajectories is investigated. We have compared our theoretical results with a recent experiment [Eichmann Nature (London)NATUAS0028-083610.1038/nature08481 461, 1261 (2009)].

Ball-morph: definition, implementation, and comparative evaluation.

PubMed

Whited, Brian; Rossignac, Jaroslaw Jarek

2011-06-01

We define b-compatibility for planar curves and propose three ball morphing techniques between pairs of b-compatible curves. Ball-morphs use the automatic ball-map correspondence, proposed by Chazal et al., from which we derive different vertex trajectories (linear, circular, and parabolic). All three morphs are symmetric, meeting both curves with the same angle, which is a right angle for the circular and parabolic. We provide simple constructions for these ball-morphs and compare them to each other and other simple morphs (linear-interpolation, closest-projection, curvature-interpolation, Laplace-blending, and heat-propagation) using six cost measures (travel-distance, distortion, stretch, local acceleration, average squared mean curvature, and maximum squared mean curvature). The results depend heavily on the input curves. Nevertheless, we found that the linear ball-morph has consistently the shortest travel-distance and the circular ball-morph has the least amount of distortion.

[A study of magnetic shielding design for a magnetic resonance imaging linac system].

PubMed

Zhang, Zheshun; Chen, Wenjing; Qiu, Yang; Zhu, Jianming

2017-12-01

One of the main technical challenges when integrating magnetic resonance imaging (MRI) systems with medical linear accelerator is the strong interference of fringe magnetic fields from the MRI system with the electron beams of linear accelerator, making the linear accelerator not to work properly. In order to minimize the interference of magnetic fields, a magnetic shielding cylinder with an open structure made of high permeability materials is designed. ANSYS Maxwell was used to simulate Helmholtz coil which generate uniform magnetic field instead of the fringe magnetic fields which affect accelerator gun. The parameters of shielding tube, such as permeability, radius, length, side thickness, bottom thickness and fringe magnetic fields strength are simulated, and the data is processed by MATLAB to compare the shielding performance. This article gives out a list of magnetic shielding effectiveness with different side thickness and bottom thickness under the optimal radius and length, which showes that this design can meet the shielding requirement for the MRI-linear accelerator system.

Differences in 1D electron plasma wake field acceleration in MeV versus GeV and linear versus blowout regimes

NASA Astrophysics Data System (ADS)

Tsiklauri, David

2018-03-01

In some laboratory and most astrophysical situations, plasma wake-field acceleration of electrons is one dimensional, i.e., variation transverse to the beam's motion can be ignored. Thus, one dimensional, particle-in-cell (PIC), fully electromagnetic simulations of electron plasma wake field acceleration are conducted in order to study the differences in electron plasma wake field acceleration in MeV versus GeV and linear versus blowout regimes. First, we show that caution needs to be taken when using fluid simulations, as PIC simulations prove that an approximation for an electron bunch not to evolve in time for a few hundred plasma periods only applies when it is sufficiently relativistic. This conclusion is true irrespective of the plasma temperature. We find that in the linear regime and GeV energies, the accelerating electric field generated by the plasma wake is similar to the linear and MeV regimes. However, because GeV energy driving bunch stays intact for a much longer time, the final acceleration energies are much larger in the GeV energies case. In the GeV energy range and blowout regime, the wake's accelerating electric field is much larger in amplitude compared with the linear case and also plasma wake geometrical size is much larger. Thus, the correct positioning of the trailing bunch is needed to achieve the efficient acceleration. For the considered case, optimally, there should be approximately (90-100)c/ωpe distance between the trailing and driving electron bunches in the GeV blowout regime.

Photoelectron linear accelerator for producing a low emittance polarized electron beam

DOEpatents

Yu, David U.; Clendenin, James E.; Kirby, Robert E.

2004-06-01

A photoelectron linear accelerator for producing a low emittance polarized electric beam. The accelerator includes a tube having an inner wall, the inner tube wall being coated by a getter material. A portable, or demountable, cathode plug is mounted within said tube, the surface of said cathode having a semiconductor material formed thereon.

MO-FG-BRC-00: Joint AAPM-ESTRO Symposium: Advances in Experimental Medical Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Experimental research in medical physics has expanded the limits of our knowledge and provided novel imaging and therapy technologies for patients around the world. However, experimental efforts are challenging due to constraints in funding, space, time and other forms of institutional support. In this joint ESTRO-AAPM symposium, four exciting experimental projects from four different countries are highlighted. Each project is focused on a different aspect of radiation therapy. From the USA, we will hear about a new linear accelerator concept for more compact and efficient therapy devices. From Canada, we will learn about novel linear accelerator target design and themore » implications for imaging and therapy. From France, we will discover a mature translational effort to incorporate theranostic nanoparticles in MR-guided radiation therapy. From Germany, we will find out about a novel in-treatment imaging modality for particle therapy. These examples of high impact, experimental medical physics research are representative of the diversity of such efforts that are on-going around the globe. J. Robar, Research is supported through collaboration with Varian Medical Systems and Brainlab AGD. Westerly, This work is supported by the Department of Radiation Oncology at the University of Colorado School of Medicine. COI: NONEK. Parodi, Part of the presented work is supported by the DFG (German Research Foundation) Cluster of Excellence MAP (Munich-Centre for Advanced Photonics) and has been carried out in collaboration with IBA.« less

MO-FG-BRC-01: MR-Guided Radiation Therapy with Gadolinium Nanoparticles: From Chalkboard to First Clinical Trials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sancey, L.

2016-06-15

Experimental research in medical physics has expanded the limits of our knowledge and provided novel imaging and therapy technologies for patients around the world. However, experimental efforts are challenging due to constraints in funding, space, time and other forms of institutional support. In this joint ESTRO-AAPM symposium, four exciting experimental projects from four different countries are highlighted. Each project is focused on a different aspect of radiation therapy. From the USA, we will hear about a new linear accelerator concept for more compact and efficient therapy devices. From Canada, we will learn about novel linear accelerator target design and themore » implications for imaging and therapy. From France, we will discover a mature translational effort to incorporate theranostic nanoparticles in MR-guided radiation therapy. From Germany, we will find out about a novel in-treatment imaging modality for particle therapy. These examples of high impact, experimental medical physics research are representative of the diversity of such efforts that are on-going around the globe. J. Robar, Research is supported through collaboration with Varian Medical Systems and Brainlab AGD. Westerly, This work is supported by the Department of Radiation Oncology at the University of Colorado School of Medicine. COI: NONEK. Parodi, Part of the presented work is supported by the DFG (German Research Foundation) Cluster of Excellence MAP (Munich-Centre for Advanced Photonics) and has been carried out in collaboration with IBA.« less

Broadband Energy Harvester Using Non-linear Polymer Spring and Electromagnetic/Triboelectric Hybrid Mechanism

PubMed Central

Gupta, Rahul Kumar; Shi, Qiongfeng; Dhakar, Lokesh; Wang, Tao; Heng, Chun Huat; Lee, Chengkuo

2017-01-01

Over the years, several approaches have been devised to widen the operating bandwidth, but most of them can only be triggered at high accelerations. In this work, we investigate a broadband energy harvester based on combination of non-linear stiffening effect and multimodal energy harvesting to obtain high bandwidth over wide range of accelerations (0.1 g–2.0 g). In order to achieve broadband behavior, a polymer based spring exhibiting multimodal energy harvesting is used. Besides, non-linear stiffening effect is introduced by using mechanical stoppers. At low accelerations (<0.5 g), the nearby mode frequencies of polymer spring contribute to broadening characteristics, while proof mass engages with mechanical stoppers to introduce broadening by non-linear stiffening at higher accelerations. The electromagnetic mechanism is employed in this design to enhance its output at low accelerations when triboelectric output is negligible. Our device displays bandwidth of 40 Hz even at low acceleration of 0.1 g and it is increased up to 68 Hz at 2 g. When non-linear stiffening is used along with multimodal energy-harvesting, the obtained bandwidth increases from 23 Hz to 68 Hz with percentage increment of 295% at 1.8 g. Further, we have demonstrated the triboelectric output measured as acceleration sensing signals in terms of voltage and current sensitivity of 4.7 Vg−1 and 19.7 nAg−1, respectively. PMID:28120924

The influence of acceleration loading curve characteristics on traumatic brain injury.

PubMed

Post, Andrew; Blaine Hoshizaki, T; Gilchrist, Michael D; Brien, Susan; Cusimano, Michael D; Marshall, Shawn

2014-03-21

To prevent brain trauma, understanding the mechanism of injury is essential. Once the mechanism of brain injury has been identified, prevention technologies could then be developed to aid in their prevention. The incidence of brain injury is linked to how the kinematics of a brain injury event affects the internal structures of the brain. As a result it is essential that an attempt be made to describe how the characteristics of the linear and rotational acceleration influence specific traumatic brain injury lesions. As a result, the purpose of this study was to examine the influence of the characteristics of linear and rotational acceleration pulses and how they account for the variance in predicting the outcome of TBI lesions, namely contusion, subdural hematoma (SDH), subarachnoid hemorrhage (SAH), and epidural hematoma (EDH) using a principal components analysis (PCA). Monorail impacts were conducted which simulated falls which caused the TBI lesions. From these reconstructions, the characteristics of the linear and rotational acceleration were determined and used for a PCA analysis. The results indicated that peak resultant acceleration variables did not account for any of the variance in predicting TBI lesions. The majority of the variance was accounted for by duration of the resultant and component linear and rotational acceleration. In addition, the components of linear and rotational acceleration characteristics on the x, y, and z axes accounted for the majority of the remainder of the variance after duration. Copyright © 2014 Elsevier Ltd. All rights reserved.

Broadband Energy Harvester Using Non-linear Polymer Spring and Electromagnetic/Triboelectric Hybrid Mechanism

NASA Astrophysics Data System (ADS)

Gupta, Rahul Kumar; Shi, Qiongfeng; Dhakar, Lokesh; Wang, Tao; Heng, Chun Huat; Lee, Chengkuo

2017-01-01

Over the years, several approaches have been devised to widen the operating bandwidth, but most of them can only be triggered at high accelerations. In this work, we investigate a broadband energy harvester based on combination of non-linear stiffening effect and multimodal energy harvesting to obtain high bandwidth over wide range of accelerations (0.1 g-2.0 g). In order to achieve broadband behavior, a polymer based spring exhibiting multimodal energy harvesting is used. Besides, non-linear stiffening effect is introduced by using mechanical stoppers. At low accelerations (<0.5 g), the nearby mode frequencies of polymer spring contribute to broadening characteristics, while proof mass engages with mechanical stoppers to introduce broadening by non-linear stiffening at higher accelerations. The electromagnetic mechanism is employed in this design to enhance its output at low accelerations when triboelectric output is negligible. Our device displays bandwidth of 40 Hz even at low acceleration of 0.1 g and it is increased up to 68 Hz at 2 g. When non-linear stiffening is used along with multimodal energy-harvesting, the obtained bandwidth increases from 23 Hz to 68 Hz with percentage increment of 295% at 1.8 g. Further, we have demonstrated the triboelectric output measured as acceleration sensing signals in terms of voltage and current sensitivity of 4.7 Vg-1 and 19.7 nAg-1, respectively.

Technical Note: Mobile accelerator guidance using an optical tracker during docking in IOERT procedures.

PubMed

Marinetto, Eugenio; Victores, Juan González; García-Sevilla, Mónica; Muñoz, Mercedes; Calvo, Felipe Ángel; Balaguer, Carlos; Desco, Manuel; Pascau, Javier

2017-10-01

Intraoperative electron radiation therapy (IOERT) involves the delivery of a high radiation dose during tumor resection in a shorter time than other radiation techniques, thus improving local control of tumors. However, a linear accelerator device is needed to produce the beam safely. Mobile linear accelerators have been designed as dedicated units that can be moved into the operating room and deliver radiation in situ. Correct and safe dose delivery is a key concern when using mobile accelerators. The applicator is commonly fixed to the patient's bed to ensure that the dose is delivered to the prescribed location, and the mobile accelerator is moved to dock the applicator to the radiation beam output (gantry). In a typical clinical set-up, this task is time-consuming because of safety requirements and the limited degree of freedom of the gantry. The objective of this study was to present a navigation solution based on optical tracking for guidance of docking to improve safety and reduce procedure time. We used an optical tracker attached to the mobile linear accelerator to track the prescribed localization of the radiation collimator inside the operating room. Using this information, the integrated navigation system developed computes the movements that the mobile linear accelerator needs to perform to align the applicator and the radiation gantry and warns the physician if docking is unrealizable according to the available degrees of freedom of the mobile linear accelerator. Furthermore, we coded a software application that connects all the necessary functioning elements and provides a user interface for the system calibration and the docking guidance. The system could safeguard against the spatial limitations of the operating room, calculate the optimal arrangement of the accelerator and reduce the docking time in computer simulations and experimental setups. The system could be used to guide docking with any commercial linear accelerator. We believe that the docking navigator we present is a major contribution to IOERT, where docking is critical when attempting to reduce surgical time, ensure patient safety and guarantee that the treatment administered follows the radiation oncologist's prescription. © 2017 American Association of Physicists in Medicine.

Impact attenuation of protective boxing and taekwondo headgear.

PubMed

O'Sullivan, David M; Fife, Gabriel P

2016-11-01

This study aimed to compare the impact attenuation performance of boxing and taekwondo headgear in terms of peak linear and rotational acceleration. To measure the impact attenuation of headgear, a standardized (American Society for Testing and Materials (ASTM) F-2397) martial arts headgear striker was used to impart impacts to a 50th Percentile Male Hybrid III Crash Test Dummy head and neck complex. Two boxing (Adidas and Greenhill) and two taekwondo (Adidas and Nike) headgear, approved by the Association Internationale de Boxe Amateur and the World Taekwondo Federation (WTF), were selected. Each of the selected headgear was fitted to the Hybrid III head and subsequently subjected to five impacts at the front and side with a maximum impact interim time of 60 seconds by the rotating striker at 8 ± 0.3 m/s. Linear and rotational acceleration were recorded at 10,000 Hz. There were significant interactions of the impact location and brand on the rotational acceleration, F(3,40) = 6.7, p < .05. There were significant main effects of both impact location F(1,40) = 9.07, p < .05 and headgear brand F(3,40) = 9.9, p < .05 on the linear acceleration. Pairwise comparisons show significant differences between the front and side for both linear and rotational acceleration. The headgear tested failed the ASTM high impact test requirement to reduce the linear acceleration to below a threshold of 150 g. Further development of headgear to reduce impact linear and rotational acceleration magnitudes should be called for by the relevant sport governing bodies and initiated by headgear manufactures.

KLYNAC: Compact linear accelerator with integrated power supply

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malyzhenkov, Alexander

Accelerators and accelerator-based light sources have a wide range of applications in science, engineering technology and medicine. Today the scienti c community is working towards improving the quality of the accelerated beam and its parameters while trying to develop technology for reducing accelerator size. This work describes a design of a compact linear accelerator (linac) prototype, resonant Klynac device, which is a combined linear accelerator and its power supply - klystron. The intended purpose of a Klynac device is to provide a compact and inexpensive alternative to a conventional 1 to 6 MeV accelerator, which typically requires a separate RFmore » source, an accelerator itself and all the associated hardware. Because the Klynac is a single structure, it has the potential to be much less sensitive to temperature variations than a system with separate klystron and linac. We start by introducing a simpli ed theoretical model for a Klynac device. We then demonstrate how a prototype is designed step-by-step using particle-in-cell simulation studies for mono- resonant and bi-resonant structures. Finally, we discuss design options from a stability point of view and required input power as well as behavior of competing modes for the actual built device.« less

Klynac: Compact Linear Accelerator with Integrated Power Supply

NASA Astrophysics Data System (ADS)

Malyzhenkov, A. V.

Accelerators and accelerator-based light sources have a wide range of applications in science, engineering technology and medicine. Today the scientific community is working towards improving the quality of the accelerated beam and its parameters, while trying to develop technology for reducing accelerator size. This work describes a design of a compact linear accelerator (linac) prototype: resonant Klynac device, which is a combined linear accelerator and its power supply - klystron. The intended purpose of a Klynac device is to provide a compact and inexpensive alternative to a conventional 1 to 6 MeV accelerator, which typically requires a separate RF source, accelerator itself and all the associated hardware. Because the Klynac is a single structure, it has the potential to be much less sensitive to temperature variations than a system with separate klystron and linac. We start by introducing a simplified theoretical model for a Klynac device. We then demonstrate how a prototype is designed step-by-step using Particle-In-Cell simulation studies for mono-resonant and bi-resonant structures. Finally, we discuss design options from a stability point of view and required input power as well as behavior of competing modes for the actual built device.

Pros and Cons of the Acceleration Scheme (NF-IDS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogacz, Alex; Bogacz, Slawomir

The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and beam shaping can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a nonâ scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. Pros and cons of various stages are discussed here in detail. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain acrossmore » the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. Close proximity of strong solenoids and superc« less

Electron acceleration via magnetic island coalescence

NASA Astrophysics Data System (ADS)

Shinohara, I.; Yumura, T.; Tanaka, K. G.; Fujimoto, M.

2009-06-01

Electron acceleration via fast magnetic island coalescence that happens as quick magnetic reconnection triggering (QMRT) proceeds has been studied. We have carried out a three-dimensional full kinetic simulation of the Harris current sheet with a large enough simulation run for two magnetic islands coalescence. Due to the strong inductive electric field associated with the non-linear evolution of the lower-hybrid-drift instability and the magnetic island coalescence process observed in the non-linear stage of the collisionless tearing mode, electrons are significantly accelerated at around the neutral sheet and the subsequent X-line. The accelerated meandering electrons generated by the non-linear evolution of the lower-hybrid-drift instability are resulted in QMRT, and QMRT leads to fast magnetic island coalescence. As a whole, the reconnection triggering and its transition to large-scale structure work as an effective electron accelerator.

Laser-plasma-based linear collider using hollow plasma channels

DOE PAGES

Schroeder, C. B.; Benedetti, C.; Esarey, E.; ...

2016-03-03

A linear electron–positron collider based on laser-plasma accelerators using hollow plasma channels is considered. Laser propagation and energy depletion in the hollow channel is discussed, as well as the overall efficiency of the laser-plasma accelerator. Example parameters are presented for a 1-TeV and 3-TeV center-of-mass collider based on laser-plasma accelerators.

Anthropometrics and maturity status: A preliminary study of youth football head impact biomechanics.

PubMed

Yeargin, Susan W; Kingsley, Payton; Mensch, Jim M; Mihalik, Jason P; Monsma, Eva V

2017-10-03

There is a paucity of head impact biomechanics research focusing on youth athletes. Little is known about how youth subconcussive head impact tolerances are related to physical size and maturation. To examine the effects of age, anthropometric and maturational status variability on head impact biomechanics. Cross-sectional. Outdoor youth football facilities in South Carolina. Thirty-four male recreational youth football players, 8 to 13yrs. Categorized by CDC standards, independent variables were: age, height, mass, BMI, and estimated peak height velocity (PHV). Participants wore a designated head impact sensor (xPatch) on their mastoid process during practices and games. Linear acceleration (g) and rotational acceleration (rad/s 2 ). Boys in the older age category had a greater linear (F=17.72; P<0.001) and rotational acceleration (F=10.74; P<0.001) than those in the younger category. Post-PHV boys had higher linear (F=9.09, P=0.002) and rotational (F=5.57, P=0.018) accelerations than those who were pre-PHV. Rotational, but not linear acceleration differed by height category with lowest impacts found for the tallest category, whereas both linear and rotational accelerations by mass differences favored average and heavy categories. BMI overweight boys, had the greatest linear (F=5.25; P=0.011) and rotational acceleration (F=4.13; P=0.260) means. Post-PHV boys who were older, taller and had longer legs, but who were not heavier, had higher impacts perhaps due to the type of impacts sustained. Taller boys' heads are above their peers possibly encouraging hits in the torso region resulting in lower impact accelerations. Obese boys did not have sequential results compared to boys in the other BMI categories probably due to league rules, player position, and lack of momentum produced. Copyright © 2017 Elsevier B.V. All rights reserved.

Technology evaluation of man-rated acceleration test equipment for vestibular research

NASA Technical Reports Server (NTRS)

Taback, I.; Kenimer, R. L.; Butterfield, A. J.

1983-01-01

The considerations for eliminating acceleration noise cues in horizontal, linear, cyclic-motion sleds intended for both ground and shuttle-flight applications are addressed. the principal concerns are the acceleration transients associated with change in direction-of-motion for the carriage. The study presents a design limit for acceleration cues or transients based upon published measurements for thresholds of human perception to linear cyclic motion. The sources and levels for motion transients are presented based upon measurements obtained from existing sled systems. The approaches to a noise-free system recommends the use of air bearings for the carriage support and moving-coil linear induction motors operating at low frequency as the drive system. Metal belts running on air bearing pulleys provide an alternate approach to the driving system. The appendix presents a discussion of alternate testing techniques intended to provide preliminary type data by means of pendulums, linear motion devices and commercial air bearing tables.

Critical system issues and modeling requirements: The problem of beam energy sweep in an electron linear induction accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turner, W.C.; Barrett, D.M.; Sampayan, S.E.

1990-08-06

In this paper we discuss system issues and modeling requirements within the context of energy sweep in an electron linear induction accelerator. When needed, particular parameter values are taken from the ETA-II linear induction accelerator at Lawrence Livermore National Laboratory. For this paper, the most important parameter is energy sweep during a pulse. It is important to have low energy sweep to satisfy the FEL resonance condition and to limit the beam corkscrew motion. It is desired to achieve {Delta}E/E = {plus minus}1% for a 50-ns flattop whereas the present level of performance is {Delta}E/E = {plus minus}1% in 10more » ns. To improve this situation we will identify a number of areas in which modeling could help increase understanding and improve our ability to design linear induction accelerators.« less

Analysis of Monte Carlo accelerated iterative methods for sparse linear systems: Analysis of Monte Carlo accelerated iterative methods for sparse linear systems

DOE PAGES

Benzi, Michele; Evans, Thomas M.; Hamilton, Steven P.; ...

2017-03-05

Here, we consider hybrid deterministic-stochastic iterative algorithms for the solution of large, sparse linear systems. Starting from a convergent splitting of the coefficient matrix, we analyze various types of Monte Carlo acceleration schemes applied to the original preconditioned Richardson (stationary) iteration. We expect that these methods will have considerable potential for resiliency to faults when implemented on massively parallel machines. We also establish sufficient conditions for the convergence of the hybrid schemes, and we investigate different types of preconditioners including sparse approximate inverses. Numerical experiments on linear systems arising from the discretization of partial differential equations are presented.

Applications of the Strategic Defense Initiative's compact accelerators

NASA Technical Reports Server (NTRS)

Montanarelli, Nick; Lynch, Ted

1991-01-01

The Strategic Defense Initiative's (SDI) investment in particle accelerator technology for its directed energy weapons program has produced breakthroughs in the size and power of new accelerators. These accelerators, in turn, have produced spinoffs in several areas: the radio frequency quadrupole linear accelerator (RFQ linac) was recently incorporated into the design of a cancer therapy unit at the Loma Linda University Medical Center, an SDI-sponsored compact induction linear accelerator may replace Cobalt-60 radiation and hazardous ethylene-oxide as a method for sterilizing medical products, and other SDIO-funded accelerators may be used to produce the radioactive isotopes oxygen-15, nitrogen-13, carbon-11, and fluorine-18 for positron emission tomography (PET). Other applications of these accelerators include bomb detection, non-destructive inspection, decomposing toxic substances in contaminated ground water, and eliminating nuclear waste.

Self-shielded electron linear accelerators designed for radiation technologies

NASA Astrophysics Data System (ADS)

Belugin, V. M.; Rozanov, N. E.; Pirozhenko, V. M.

2009-09-01

This paper describes self-shielded high-intensity electron linear accelerators designed for radiation technologies. The specific property of the accelerators is that they do not apply an external magnetic field; acceleration and focusing of electron beams are performed by radio-frequency fields in the accelerating structures. The main characteristics of the accelerators are high current and beam power, but also reliable operation and a long service life. To obtain these characteristics, a number of problems have been solved, including a particular optimization of the accelerator components and the application of a variety of specific means. The paper describes features of the electron beam dynamics, accelerating structure, and radio-frequency power supply. Several compact self-shielded accelerators for radiation sterilization and x-ray cargo inspection have been created. The introduced methods made it possible to obtain a high intensity of the electron beam and good performance of the accelerators.

Thomas Jefferson National Accelerator Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grames, Joseph; Higinbotham, Douglas; Montgomery, Hugh

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. Themore » 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.« less

First heavy ion beam tests with a superconducting multigap CH cavity

NASA Astrophysics Data System (ADS)

Barth, W.; Aulenbacher, K.; Basten, M.; Busch, M.; Dziuba, F.; Gettmann, V.; Heilmann, M.; Kürzeder, T.; Miski-Oglu, M.; Podlech, H.; Rubin, A.; Schnase, A.; Schwarz, M.; Yaramyshev, S.

2018-02-01

Very compact accelerating-focusing structures, as well as short focusing periods, high accelerating gradients and short drift spaces are strongly required for superconducting (sc) accelerator sections operating at low and medium energies for continuous wave (cw) heavy ion beams. To keep the GSI-super heavy element (SHE) program competitive on a high level and even beyond, a standalone sc cw linac (Helmholtz linear accelerator) in combination with the GSI high charge state injector (HLI), upgraded for cw operation, is envisaged. Recently the first linac section (financed by Helmholtz Institute Mainz (HIM) and GSI) as a demonstration of the capability of 217 MHz multigap crossbar H-mode structures (CH) has been commissioned and extensively tested with heavy ion beam from the HLI. The demonstrator setup reached acceleration of heavy ions up to the design beam energy. The required acceleration gain was achieved with heavy ion beams even above the design mass to charge ratio at high beam intensity and full beam transmission. This paper presents systematic beam measurements with varying rf amplitudes and phases of the CH cavity, as well as phase space measurements for heavy ion beams with different mass to charge ratio. The worldwide first and successful beam test with a superconducting multigap CH cavity is a milestone of the R&D work of HIM and GSI in collaboration with IAP in preparation of the HELIAC project and other cw-ion beam applications.

Radiological Studies for the LCLS Beam Abort System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santana Leitner, M.; Vollaire, J.; Mao, X.S.

2008-03-25

The Linac Coherent Light Source (LCLS), a pioneer hard x-ray free electron laser is currently under construction at the Stanford Linear Accelerator Center. It is expected that by 2009 LCLS will deliver laser pulses of unprecedented brightness and short length, which will be used in several forefront research applications. This ambitious project encompasses major design challenges to the radiation protection like the numerous sources and the number of surveyed objects. In order to sort those, the showers from various loss sources have been tracked along a detailed model covering 1/2 mile of LCLS accelerator by means of the Monte Carlomore » intra nuclear cascade codes FLUKA and MARS15. This article covers the FLUKA studies of heat load; prompt and residual dose and environmental impact for the LCLS beam abort system.« less

SU-D-207-05: Real-Time Intrafractional Motion Tracking During VMAT Delivery Using a Conventional Elekta CBCT System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Yang-Kyun; Sharp, Gregory C.; Gierga, David P.

2015-06-15

Purpose: Real-time kV projection streaming capability has become recently available for Elekta XVI version 5.0. This study aims to investigate the feasibility and accuracy of real-time fiducial marker tracking during CBCT acquisition with or without simultaneous VMAT delivery using a conventional Elekta linear accelerator. Methods: A client computer was connected to an on-board kV imaging system computer, and receives and processes projection images immediately after image acquisition. In-house marker tracking software based on FFT normalized cross-correlation was developed and installed in the client computer. Three gold fiducial markers with 3 mm length were implanted in a pelvis-shaped phantom with 36more » cm width. The phantom was placed on a programmable motion platform oscillating in anterior-posterior and superior-inferior directions simultaneously. The marker motion was tracked in real-time for (1) a kV-only CBCT scan with treatment beam off and (2) a kV CBCT scan during a 6-MV VMAT delivery. The exposure parameters per projection were 120 kVp and 1.6 mAs. Tracking accuracy was assessed by comparing superior-inferior positions between the programmed and tracked trajectories. Results: The projection images were successfully transferred to the client computer at a frequency of about 5 Hz. In the kV-only scan, highly accurate marker tracking was achieved over the entire range of cone-beam projection angles (detection rate / tracking error were 100.0% / 0.6±0.5 mm). In the kV-VMAT scan, MV-scatter degraded image quality, particularly for lateral projections passing through the thickest part of the phantom (kV source angle ranging 70°-110° and 250°-290°), resulting in a reduced detection rate (90.5%). If the lateral projections are excluded, tracking performance was comparable to the kV-only case (detection rate / tracking error were 100.0% / 0.8±0.5 mm). Conclusion: Our phantom study demonstrated a promising Result for real-time motion tracking using a conventional Elekta linear accelerator. MV-scatter suppression is needed to improve tracking accuracy during MV delivery. This research is funded by Motion Management Research Grant from Elekta.« less

Inviscid linear stability analysis of two vertical columns of different densities in a gravitational acceleration field

DOE PAGES

Prathama, Aditya Heru; Pantano, Carlos

2017-08-09

Here, we study the inviscid linear stability of a vertical interface separating two fluids of different densities and subject to a gravitational acceleration field parallel to the interface. In this arrangement, the two free streams are constantly accelerated, which means that the linear stability analysis is not amenable to Fourier or Laplace solution in time. Instead, we derive the equations analytically by the initial-value problem method and express the solution in terms of the well-known parabolic cylinder function. The results, which can be classified as an accelerating Kelvin–Helmholtz configuration, show that even in the presence of surface tension, the interfacemore » is unconditionally unstable at all wavemodes. This is a consequence of the ever increasing momentum of the free streams, as gravity accelerates them indefinitely. The instability can be shown to grow as the exponential of a quadratic function of time.« less

Effects of laser polarization on electrostatic shock ion acceleration in near-critical plasmas

NASA Astrophysics Data System (ADS)

Kim, Young-Kuk; Kang, Teyoun; Hur, Min Sup

2016-10-01

Collisionless electrostatic shock ion acceleration has become a major regime of laser-driven ion acceleration owing to generation of quasi-monoenergetic ion beams from moderate parametric conditions of lasers and plasmas in comparison with target-normal-sheath-acceleration or radiation pressure acceleration. In order to construct the shock, plasma heating is an essential condition for satisfying Mach number condition 1.5

The Louisiana Accelerated Schools Project First Year Evaluation Report.

ERIC Educational Resources Information Center

St. John, Edward P.; And Others

The Louisiana Accelerated Schools Project (LASP) is a statewide network of schools that are changing from the traditional mode of schooling for at-risk students, which stresses remediation, to one of acceleration, which stresses accelerated learning for all students. The accelerated schools process provides a systematic approach to the…

International Workshop on Linear Colliders 2010

ScienceCinema

Lebrun, Ph.

2018-06-20

IWLC2010 International Workshop on Linear Colliders 2010ECFA-CLIC-ILC joint meeting: Monday 18 October - Friday 22 October 2010Venue: CERN and CICG (International Conference Centre Geneva, Switzerland). This year, the International Workshop on Linear Colliders organized by the European Committee for Future Accelerators (ECFA) will study the physics, detectors and accelerator complex of a linear collider covering both CLIC and ILC options. Contact Workshop Secretariat  IWLC2010 is hosted by CERN.

International Workshop on Linear Colliders 2010

ScienceCinema

Yamada, Sakue

2018-05-24

IWLC2010 International Workshop on Linear Colliders 2010ECFA-CLIC-ILC joint meeting: Monday 18 October - Friday 22 October 2010Venue: CERN and CICG (International Conference Centre Geneva, Switzerland) This year, the International Workshop on Linear Colliders organized by the European Committee for Future Accelerators (ECFA) will study the physics, detectors and accelerator complex of a linear collider covering both CLIC and ILC options. Contact Workshop Secretariat  IWLC2010 is hosted by CERN

Adaptation to vestibular disorientation. IX, Influence of head position on the habituation of vertical nystagmus.

DOT National Transportation Integrated Search

1968-03-01

Interactions of linear and angular accelerations are frequently experienced by pilots during aircraft maneuvers. Several recent studies have indicated that the otoliths (detectors of linear acceleration) may influence responses of the semicircular ca...

Conduction cooling systems for linear accelerator cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kephart, Robert

A conduction cooling system for linear accelerator cavities. The system conducts heat from the cavities to a refrigeration unit using at least one cavity cooler interconnected with a cooling connector. The cavity cooler and cooling connector are both made from solid material having a very high thermal conductivity of approximately 1.times.10.sup.4 W m.sup.-1 K.sup.-1 at temperatures of approximately 4 degrees K. This allows for very simple and effective conduction of waste heat from the linear accelerator cavities to the cavity cooler, along the cooling connector, and thence to the refrigeration unit.

Assessment of human exposure doses received by activation of medical linear accelerator components

NASA Astrophysics Data System (ADS)

Lee, D.-Y.; Kim, J.-H.; Park, E.-T.

2017-08-01

This study analyzes the radiation exposure dose that an operator can receive from radioactive components during maintenance or repair of a linear accelerator. This study further aims to evaluate radiological safety. Simulations are performed on 10 MV and 15 MV photon beams, which are the most frequently used high-energy beams in clinics. The simulation analyzes components in order of activity and the human exposure dose based on the amount of neutrons received. As a result, the neutron dose, radiation dose, and human exposure dose are ranked in order of target, primary collimator, flattening filter, multi-leaf collimator, and secondary collimator, where the minimum dose is 9.34E-07 mSv/h and the maximum is 1.71E-02 mSv/h. When applying the general dose limit (radiation worker 20 mSv/year, pubic 1 mSv/year) in accordance with the Nuclear Safety Act, all components of a linear accelerator are evaluated as below the threshold value. Therefore, the results suggest that there is no serious safety issue for operators in maintaining and repairing a linear accelerator. Nevertheless, if an operator recognizes an exposure from the components of a linear accelerator during operation and considers the operating time and shielding against external exposure, exposure of the operator is expected to be minimized.

Third party EPID with IGRT capability retrofitted onto an existing medical linear accelerator

PubMed Central

Odero, DO; Shimm, DS

2009-01-01

Radiation therapy requires precision to avoid unintended irradiation of normal organs. Electronic Portal Imaging Devices (EPIDs), can help with precise patient positioning for accurate treatment. EPIDs are now bundled with new linear accelerators, or they can be purchased from the Linac manufacturer for retrofit. Retrofitting a third party EPID to a linear accelerator can pose challenges. The authors describe a relatively inexpensive third party CCD camera-based EPID manufactured by TheraView (Cablon Medical B.V.), installed onto a Siemens Primus linear accelerator, and integrated with a Lantis record and verify system, an Oldelft simulator with Digital Therapy Imaging (DTI) unit, and a Philips ADAC Pinnacle treatment planning system (TPS). This system integrates well with existing equipment and its software can process DICOM images from other sources. The system provides a complete imaging system that eliminates the need for separate software for portal image viewing, interpretation, analysis, archiving, image guided radiation therapy and other image management applications. It can also be accessed remotely via safe VPN tunnels. TheraView EPID retrofit therefore presents an example of a less expensive alternative to linear accelerator manufacturers’ proprietary EPIDs suitable for implementation in third world countries radiation therapy departments which are often faced with limited financial resources. PMID:21611056

Third party EPID with IGRT capability retrofitted onto an existing medical linear accelerator.

PubMed

Odero, D O; Shimm, D S

2009-07-01

Radiation therapy requires precision to avoid unintended irradiation of normal organs. Electronic Portal Imaging Devices (EPIDs), can help with precise patient positioning for accurate treatment. EPIDs are now bundled with new linear accelerators, or they can be purchased from the Linac manufacturer for retrofit. Retrofitting a third party EPID to a linear accelerator can pose challenges. The authors describe a relatively inexpensive third party CCD camera-based EPID manufactured by TheraView (Cablon Medical B.V.), installed onto a Siemens Primus linear accelerator, and integrated with a Lantis record and verify system, an Oldelft simulator with Digital Therapy Imaging (DTI) unit, and a Philips ADAC Pinnacle treatment planning system (TPS). This system integrates well with existing equipment and its software can process DICOM images from other sources. The system provides a complete imaging system that eliminates the need for separate software for portal image viewing, interpretation, analysis, archiving, image guided radiation therapy and other image management applications. It can also be accessed remotely via safe VPN tunnels. TheraView EPID retrofit therefore presents an example of a less expensive alternative to linear accelerator manufacturers' proprietary EPIDs suitable for implementation in third world countries radiation therapy departments which are often faced with limited financial resources.

US Particle Accelerators at Age 50.

ERIC Educational Resources Information Center

Wilson, R. R.

1981-01-01

Reviews the development of accelerators over the past 50 years. Topics include: types of accelerators, including cyclotrons; sociology of accelerators (motivation, financing, construction, and use); impact of war; national laboratories; funding; applications; future projects; foreign projects; and international collaborations. (JN)

Proc. of the workshop on pushing the limits of RF superconductivity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, K-J., Eyberger, C., editors

2005-04-13

For three days in late September last year, some sixty experts in RF superconductivity from around the world came together at Argonne to discuss how to push the limits of RF superconductivity for particle accelerators. It was an intense workshop with in-depth presentations and ample discussions. There was added excitement due to the fact that, a few days before the workshop, the International Technology Recommendation Panel had decided in favor of superconducting technology for the International Linear Collider (ILC), the next major high-energy physics accelerator project. Superconducting RF technology is also important for other large accelerator projects that are eithermore » imminent or under active discussion at this time, such as the Rare Isotope Accelerator (RIA) for nuclear physics, energy recovery linacs (ERLs), and x-ray free-electron lasers. For these accelerators, the capability in maximum accelerating gradient and/or the Q value is essential to limit the length and/or operating cost of the accelerators. The technological progress of superconducting accelerators during the past two decades has been truly remarkable, both in low-frequency structures for acceleration of protons and ions as well as in high-frequency structures for electrons. The requirements of future accelerators demand an even higher level of performance. The topics of this workshop are therefore highly relevant and timely. The presentations given at the workshop contained authoritative reviews of the current state of the art as well as some original materials that previously had not been widely circulated. We therefore felt strongly that these materials should be put together in the form of a workshop proceeding. The outcome is this report, which consists of two parts: first, a collection of the scholarly papers prepared by some of the participants and second, copies of the viewgraphs of all presentations. The presentation viewgraphs, in full color, are also available from the Workshop Presentations link on the workshop's web page at http://www.aps.anl.gov/conferences/RFSCLimits/. I would like to thank all of the participants for their lively contributions to the workshop and to these proceedings, and Helen Edwards and Hasan Padamsee for their help in developing the workshop program. I also thank Cathy Eyberger, Kelly Jaje, and Renee Lanham for working very hard to take care of the administrative details, in particular Cathy for editing this report.« less

Permanent magnet focused X-band photoinjector

DOEpatents

Yu, David U. L.; Rosenzweig, James

2002-09-10

A compact high energy photoelectron injector integrates the photocathode directly into a multicell linear accelerator with no drift space between the injection and the linac. High electron beam brightness is achieved by accelerating a tightly focused electron beam in an integrated, multi-cell, X-band rf linear accelerator (linac). The photoelectron linac employs a Plane-Wave-Transformer (PWT) design which provides strong cell-to-cell coupling, easing manufacturing tolerances and costs.

Staging optics considerations for a plasma wakefield acceleration linear collider

NASA Astrophysics Data System (ADS)

Lindstrøm, C. A.; Adli, E.; Allen, J. M.; Delahaye, J. P.; Hogan, M. J.; Joshi, C.; Muggli, P.; Raubenheimer, T. O.; Yakimenko, V.

2016-09-01

Plasma wakefield acceleration offers acceleration gradients of several GeV/m, ideal for a next-generation linear collider. The beam optics requirements between plasma cells include injection and extraction of drive beams, matching the main beam beta functions into the next cell, canceling dispersion as well as constraining bunch lengthening and chromaticity. To maintain a high effective acceleration gradient, this must be accomplished in the shortest distance possible. A working example is presented, using novel methods to correct chromaticity, as well as scaling laws for a high energy regime.

HEAVY ION LINEAR ACCELERATOR

DOEpatents

Van Atta, C.M.; Beringer, R.; Smith, L.

1959-01-01

A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.

Angular Impact Mitigation System for Bicycle Helmets to Reduce Head Acceleration and Risk of Traumatic Brain Injury

PubMed Central

Hansen, Kirk; Dau, Nathan; Feist, Florian; Deck, Caroline; Willinger, Rémy; Madey, Steven M.; Bottlang, Michael

2013-01-01

Angular acceleration of the head is a known cause of traumatic brain injury (TBI), but contemporary bicycle helmets lack dedicated mechanisms to mitigate angular acceleration. A novel Angular Impact Mitigation (AIM) system for bicycle helmets has been developed that employs an elastically suspended aluminum honeycomb liner to absorb linear acceleration in normal impacts as well as angular acceleration in oblique impacts. This study tested bicycle helmets with and without AIM technology to comparatively assess impact mitigation. Normal impact tests were performed to measure linear head acceleration. Oblique impact tests were performed to measure angular head acceleration and neck loading. Furthermore, acceleration histories of oblique impacts were analyzed in a computational head model to predict the resulting risk of TBI in the form of concussion and diffuse axonal injury (DAI). Compared to standard helmets, AIM helmets resulted in a 14% reduction in peak linear acceleration (p < 0.001), a 34% reduction in peak angular acceleration (p < 0.001), and a 22% to 32% reduction in neck loading (p < 0.001). Computational results predicted that AIM helmets reduced the risk of concussion and DAI by 27% and 44%, respectively. In conclusion, these results demonstrated that AIM technology could effectively improve impact mitigation compared to a contemporary expanded polystyrene-based bicycle helmet, and may enhance prevention of bicycle-related TBI. Further research is required. PMID:23770518

Accelerator science and technology in Europe 2008-2017

NASA Astrophysics Data System (ADS)

Romaniuk, Ryszard S.

2013-10-01

European Framework Research Projects have recently added a lot of meaning to the building process of the ERA - the European Research Area. Inside this, the accelerator technology plays an essential role. Accelerator technology includes large infrastructure and intelligent, modern instrumentation embracing mechatronics, electronics, photonics and ICT. During the realization of the European research and infrastructure project FP6 CARE 2004-2008 (Coordinated Accelerator Research in Europe), concerning the development of large accelerator infrastructure in Europe, it was decided that a scientific editorial series of peer-reviewed monographs from this research area will be published in close relation with the projects. It was a completely new and quite brave idea to combine a kind of a strictly research publisher with a transient project, lasting only four or five years. Till then nobody did something like that. The idea turned out to be a real success. The publications now known and valued in the accelerator world, as the (CERN-WUT) Editorial Series on Accelerator Science and Technology, is successfully continued in already the third European project EuCARD2 and has logistic guarantees, for the moment, till the 2017, when it will mature to its first decade. During the realization of the European projects EuCARD (European Coordination for Accelerator R&D 2009-2013 and TIARA (Test Infrastructure of Accelerator Research Area in Europe) there were published 18 volumes in this series. The ambitious plans for the nearest years is to publish, hopefully, a few tens of new volumes. Accelerator science and technology is one of a key enablers of the developments in the particle physic, photon physics and also applications in medicine and industry. The paper presents a digest of the research results in the domain of accelerator science and technology in Europe, published in the monographs of the European Framework Projects (FP) on accelerator technology. The succession of CARE, EuCARD and EuCARD Projects is evidently creating a new quality in the European Accelerator Research. It is consolidating the technical and research communities in a new way, completely different than the traditional ones, for example via the periodic topical conferences.

The detrimental effect of friction on space microgravity robotics

NASA Technical Reports Server (NTRS)

Newman, Wyatt S.; Glosser, Gregory D.; Miller, Jeffrey H.; Rohn, Douglas

1992-01-01

The authors present an analysis of why control systems are ineffective in compensating for acceleration disturbances due to Coulomb friction. Linear arguments indicate that the effects of Coulomb friction on a body are most difficult to reject when the control actuator is separated from the body of compliance. The linear arguments were illustrated in a nonlinear simulation of optimal linear tracking control in the presence of nonlinear friction. The results of endpoint acceleration measurements for four robot designs are presented and are compared with simulation and to equivalent measurements on a human. It is concluded that Coulomb friction in common bearings and transmission induces unacceptable levels of endpoint acceleration, that these accelerations cannot be adequately attenuated by control, and that robots for microgravity work will require special design considerations for inherently low friction.

Accelerators for society: succession of European infrastructural projects: CARE, EuCARD, TIARA, EuCARD2

NASA Astrophysics Data System (ADS)

Romaniuk, Ryszard S.

2013-10-01

Accelerator science and technology is one of a key enablers of the developments in the particle physic, photon physics and also applications in medicine and industry. The paper presents a digest of the research results in the domain of accelerator science and technology in Europe, shown during the realization of CARE (Coordinated Accelerator R&D), EuCARD (European Coordination of Accelerator R&D) and during the national annual review meeting of the TIARA - Test Infrastructure of European Research Area in Accelerator R&D. The European projects on accelerator technology started in 2003 with CARE. TIARA is an European Collaboration of Accelerator Technology, which by running research projects, technical, networks and infrastructural has a duty to integrate the research and technical communities and infrastructures in the global scale of Europe. The Collaboration gathers all research centers with large accelerator infrastructures. Other ones, like universities, are affiliated as associate members. TIARA-PP (preparatory phase) is an European infrastructural project run by this Consortium and realized inside EU-FP7. The paper presents a general overview of CARE, EuCARD and especially TIARA activities, with an introduction containing a portrait of contemporary accelerator technology and a digest of its applications in modern society. CARE, EuCARD and TIARA activities integrated the European accelerator community in a very effective way. These projects are expected very much to be continued.

Development of a dual-pulse RF driver for an S-band (= 2856 MHz) RF electron linear accelerator

NASA Astrophysics Data System (ADS)

Cha, Sungsu; Kim, Yujong; Lee, Byeong-No; Lee, Byung Cheol; Cha, Hyungki; Ha, Jang Ho; Park, Hyung Dal; Lee, Seung Hyun; Kim, Hui Su; Buaphad, Pikad

2016-04-01

The radiation equipment research division of Korea Atomic Energy Research Institute has developed a Container Inspection System (CIS) using a Radio Frequency (RF) electron linear accelerator for port security. The primary purpose of the CIS is to detect nuclear materials and explosives, as well country-specific prohibited substances, e.g., smuggled. The CIS consists of a 9/6 MeV dualenergy electron linear accelerator for distinguishing between organic and inorganic materials. The accelerator consists of an electron gun, an RF accelerating structure, an RF driver, a modulator, electromagnets, a cooling system, a X-ray generating target, X-ray collimator, a detector, and a container moving system. The RF driver is an important part of the configuration because it is the RF power source: it supplies the RF power to the accelerating structure. A unique aspect of the RF driver is that it generates dual RF power to generate dual energy (9/6 MeV). The advantage of this RF driver is that it can allow the pulse width to vary and can be used to obtain a wide range of energy output, and pulse repetition rates up to 300 Hz. For this reason, 140 W (5 MW - 9 MeV) and 37 W (3.4 MW - 6 MeV) power outputs are available independently. A high power test for 20 minutes demonstrate that stable dual output powers can be generated. Moreover, the dual power can be applied to the accelerator which has stable accelerator operation. In this paper, the design, fabrication and high power test of the RF driver for the RF electron linear accelerator (linac) are presented.

Study of quality assurance regulations for linear accelerators in Korea: A comparison study between the current status in Korea and the international guidelines

NASA Astrophysics Data System (ADS)

Lee, Hyunho; Jeong, Seonghoon; Jo, Yunhui; Yoon, Myonggeun

2015-07-01

Quality assurance (QA) for medical linear accelerators is indispensable for appropriate cancer treatment. Some international organizations and advanced Western countries have provided QA guidelines for linear accelerators. Currently, QA regulations for linear accelerators in Korean hospitals specify a system in which each hospital stipulates its independent hospital-based protocols for QA procedures (HP_QAPs) and conducts QA based on those HP_QAPs while regulatory authorities verify whether items under those HP_QAPs have been performed. However, because this regulatory method cannot guarantee the quality of universal treatment and QA items with tolerance criteria are different in many hospitals, the presentation of standardized QA items and tolerance criteria is essential. In this study, QA items in HP_QAPs from various hospitals and those presented by international organizations, such as the International Atomic Energy Agency, the European Union, and the American Association of Physicist in Medicine, and by advanced Western countries, such as the USA, the UK, and Canada, were compared. Concordance rates between QA items for linear accelerators that were presented by the aforementioned organizations and those currently being implemented in Korean hospitals were shown to exhibit a daily QA of 50%, a weekly QA of 22%, a monthly QA of 43%, and an annual QA of 65%, and the overall concordance rates of all QA items were approximately 48%. In the comparison between QA items being implemented in Korean hospitals and those being implemented in advanced Western countries, concordance rates were shown to exhibit a daily QA of 50%, a weekly QA of 33%, a monthly QA of 60%, and an annual QA of 67%, and the overall concordance rates of all QA items were approximately 57%. The results of this study indicate that the HP_QAPs currently implemented by Korean hospitals as QA standards for linear accelerators used in radiation therapy do not meet international standards. If this problem is to be solved, national standardized QA items and procedures for linear accelerators need to be developed.

The Accelerated Schools Movement: Expansion and Support through Accelerated Schools Centers.

ERIC Educational Resources Information Center

Brunner, Ilse; And Others

From 1987 to 1995, the Accelerated Schools Project moved from a two-school pilot project to a national movement of over 700 schools in 35 states. This paper examines how the Accelerated Schools Centers have helped the expansion of the accelerated schools movement by recruiting and supporting schools in their regions, and how their institutional…

The hydrodynamics of linear accelerations in bluegill sunfish, Lepomis macrochirus

NASA Astrophysics Data System (ADS)

Wise, Tyler; Boden, Alex; Schwalbe, Margot; Tytell, Eric

2015-11-01

As fish swim, their body interacts with the fluid around them in order to generate thrust. In this study, we examined the hydrodynamics of linear acceleration by bluegill sunfish, Lepomis macrochirus, which swims using a carangiform mode. Carangiform swimmers primarily use their caudal fin and posterior body for propulsion, which is different from anguilliform swimmers, like eels, that undulate almost their whole body to swim. Most previous studies have examined steady swimming, but few have looked at linear accelerations, even though most fish do not often swim steadily. During steady swimming, thrust and drag forces are balanced, which makes it difficult to separate the two, but during acceleration, thrust exceeds drag, making it easier to measure; this may reveal insights into how thrust is produced. This study used particle image velocimetry (PIV) to compare the structure of the wake during steady swimming and acceleration and to estimate the axial force. Axial force increased during acceleration, but the orientation of the vortices did not differ between steady swimming and acceleration, which is different than anguilliform swimmers, whose wakes change structure during acceleration. This difference may point to fundamental differences between the two swimming modes. This material is based upon work supported by the U. S. Army Research Office under grant number W911NF-14-1-0494.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, Salman, E-mail: sksafi@comsats.edu.pk

The dynamics of tripartite entanglement of fermionic system in noninertial frames through linear contraction criterion when one or two observers are accelerated is investigated. In one observer accelerated case the entanglement measurement is not invariant with respect to the partial realignment of different subsystems and for two observers accelerated case it is invariant. It is shown that the acceleration of the frame does not generate entanglement in any bipartite subsystems. Unlike the bipartite states, the genuine tripartite entanglement does not completely vanish in both one observer accelerated and two observers accelerated cases even in the limit of infinite acceleration. Themore » degradation of tripartite entanglement is fast when two observers are accelerated than when one observer is accelerated. It is shown that tripartite entanglement is a better resource for quantum information processing than the bipartite entanglement in noninertial frames. - Highlights: • Tripartite entanglement of fermionic system in noninertial frames is studied. • Linear contraction criterion for quantifying tripartite entanglement is used. • Acceleration does not produce any bipartite entanglement. • The invariance of entanglement quantifier depends on accelerated observers. • The tripartite entanglement degrades against the acceleration, it never vanishes.« less

Theoretical and Computational Investigation of High-Brightness Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Chiping

Theoretical and computational investigations of adiabatic thermal beams have been carried out in parameter regimes relevant to the development of advanced high-brightness, high-power accelerators for high-energy physics research and for various applications such as light sources. Most accelerator applications require high-brightness beams. This is true for high-energy accelerators such as linear colliders. It is also true for energy recovery linacs (ERLs) and free electron lasers (FELs) such as x-ray free electron lasers (XFELs). The breakthroughs and highlights in our research in the period from February 1, 2013 to November 30, 2013 were: a) Completion of a preliminary theoretical and computationalmore » study of adiabatic thermal Child-Langmuir flow (Mok, 2013); and b) Presentation of an invited paper entitled ?Adiabatic Thermal Beams in a Periodic Focusing Field? at Space Charge 2013 Workshop, CERN, April 16-19, 2013 (Chen, 2013). In this report, an introductory background for the research project is provided. Basic theory of adiabatic thermal Child-Langmuir flow is reviewed. Results of simulation studies of adiabatic thermal Child-Langmuir flows are discussed.« less

The ESS Superconducting RF Cavity and Cryomodule Cryogenic Processes

NASA Astrophysics Data System (ADS)

Darve, C.; Elias, N.; Molloy, S.; Bosland, P.; Renard, B.; Bousson, S.; Olivier, G.; Reynet, D.; Thermeau, J. P.

The European Spallation Source (ESS) is one of Europe's largest research infrastructures, tobring new insights to the grand challenges of science and innovation in fields as diverse as material and life sciences, energy, environmental technology, cultural heritage,solid-state and fundamental physics by the end of the decade. The collaborative project is funded by a collaboration of 17 European countries and is under design and construction in Lund, Sweden. A 5 MW, long pulse proton accelerator is used to reach this goal. The pulsed length is 2.86 ms and the repetition frequency is 14 Hz (4% duty cycle). The choice of SRF technology is a key element in the development of the ESS linear accelerator (linac). The superconducting linacis composed of one section of spoke cavity cryomodules(352.21 MHz) and two sections of elliptical cavity cryomodules (704.42 MHz). These cryomodules contain niobium SRF cavities operating at 2 K, cooled by the accelerator cryoplantthrough the cryogenic distribution system. This paper presents the superconducting RF cavity and cryomodule cryogenic processes, which are developed for the technology demonstrators and to be ultimately integrated for the ESS tunnel operation.

Induction linear accelerators

NASA Astrophysics Data System (ADS)

Birx, Daniel

1992-03-01

Among the family of particle accelerators, the Induction Linear Accelerator is the best suited for the acceleration of high current electron beams. Because the electromagnetic radiation used to accelerate the electron beam is not stored in the cavities but is supplied by transmission lines during the beam pulse it is possible to utilize very low Q (typically<10) structures and very large beam pipes. This combination increases the beam breakup limited maximum currents to of order kiloamperes. The micropulse lengths of these machines are measured in 10's of nanoseconds and duty factors as high as 10-4 have been achieved. Until recently the major problem with these machines has been associated with the pulse power drive. Beam currents of kiloamperes and accelerating potentials of megavolts require peak power drives of gigawatts since no energy is stored in the structure. The marriage of liner accelerator technology and nonlinear magnetic compressors has produced some unique capabilities. It now appears possible to produce electron beams with average currents measured in amperes, peak currents in kiloamperes and gradients exceeding 1 MeV/meter, with power efficiencies approaching 50%. The nonlinear magnetic compression technology has replaced the spark gap drivers used on earlier accelerators with state-of-the-art all-solid-state SCR commutated compression chains. The reliability of these machines is now approaching 1010 shot MTBF. In the following paper we will briefly review the historical development of induction linear accelerators and then discuss the design considerations.

Quantitative Approach to Failure Mode and Effect Analysis for Linear Accelerator Quality Assurance

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Daniel, Jennifer C., E-mail: jennifer.odaniel@duke.edu; Yin, Fang-Fang

Purpose: To determine clinic-specific linear accelerator quality assurance (QA) TG-142 test frequencies, to maximize physicist time efficiency and patient treatment quality. Methods and Materials: A novel quantitative approach to failure mode and effect analysis is proposed. Nine linear accelerator-years of QA records provided data on failure occurrence rates. The severity of test failure was modeled by introducing corresponding errors into head and neck intensity modulated radiation therapy treatment plans. The relative risk of daily linear accelerator QA was calculated as a function of frequency of test performance. Results: Although the failure severity was greatest for daily imaging QA (imaging vsmore » treatment isocenter and imaging positioning/repositioning), the failure occurrence rate was greatest for output and laser testing. The composite ranking results suggest that performing output and lasers tests daily, imaging versus treatment isocenter and imaging positioning/repositioning tests weekly, and optical distance indicator and jaws versus light field tests biweekly would be acceptable for non-stereotactic radiosurgery/stereotactic body radiation therapy linear accelerators. Conclusions: Failure mode and effect analysis is a useful tool to determine the relative importance of QA tests from TG-142. Because there are practical time limitations on how many QA tests can be performed, this analysis highlights which tests are the most important and suggests the frequency of testing based on each test's risk priority number.« less

Interplay effect on a 6-MV flattening-filter-free linear accelerator with high dose rate and fast multi-leaf collimator motion treating breast and lung phantoms.

PubMed

Netherton, Tucker; Li, Yuting; Nitsch, Paige; Shaitelman, Simona; Balter, Peter; Gao, Song; Klopp, Ann; Muruganandham, Manickam; Court, Laurence

2018-06-01

Using a new linear accelerator with high dose rate (800 MU/min), fast MLC motions (5.0 cm/s), fast gantry rotation (15 s/rotation), and 1 cm wide MLCs, we aimed to quantify the effects of complexity, arc number, and fractionation on interplay for breast and lung treatments under target motion. To study lung interplay, eight VMAT plans (1-6 arcs) and four-nine-field sliding-window IMRT plans varying in complexity were created. For the breast plans, four-four-field sliding-window IMRT plans were created. Using the Halcyon 1.0 linear accelerator, each plan was delivered five times each under sinusoidal breathing motion to a phantom with 20 implanted MOSFET detectors; MOSFET dose (cGy), delivery time, and MU/cGy values were recorded. Maximum and mean dose deviations were calculated from MOSFET data. The number of MOSFETs with at least 19 of 20 detectors agreeing with their expected dose within 5% per fraction was calculated across 10 6 iterations to model dose deviation as function of fraction number for all plan variants. To put interplay plans into clinical context, additional IMRT and VMAT plans were created and delivered for the sites of head and neck, prostate, whole brain, breast, pelvis, and lung. Average modulation and interplay effect were compared to those from conventional linear accelerators, as reported from previous studies. The mean beam modulation for plans created for the Halcyon 1.0 linear accelerator was 2.9 MU/cGy (two- to four-field IMRT breast plans), 6.2 MU/cGy (at least five-field IMRT), and 3.6 MU/cGy (four-arc VMAT). To achieve treatment plan objectives, Halcyon 1.0 VMAT plans require more arcs and modulation than VMAT on conventional linear accelerators. Maximum and mean dose deviations increased with increasing plan complexity under tumor motion for breast and lung treatments. Concerning VMAT plans under motion, maximum, and mean dose deviations were higher for one arc than for two arcs regardless of plan complexity. For plan variants with maximum dose deviations greater than 3.7%, dose deviation as a function of fraction number was protracted. For treatments on the Halcyon 1.0 linear accelerator, the convergence of dose deviation with fraction number happened more slowly than reported for conventional linear accelerators. However, if plan complexity is reduced for IMRT and if tumor motion is less than ~10-mm, interplay is greatly reduced. To minimize dose deviations across multiple fractions for dynamic targets, we recommend limiting treatment plan complexity and avoiding one-arc VMAT on the Halcyon 1.0 linear accelerator when interplay is a concern. © 2018 American Association of Physicists in Medicine.

Introduction

NASA Astrophysics Data System (ADS)

Takayama, Ken; Briggs*, Richard J.

The motivation for the initial development of linear induction accelerators starting in the early 1960s came mainly from applications requiring intense electron pulses with beam currents and a charge per pulse above the range accessible to RF accelerators, and with particle energies beyond the capabilities of single stage pulsed-power diodes. The linear induction accelerators developed to meet these needs utilize a series of induction cells containing magnetic cores (torroidal geometry) driven directly by pulse modulators (pulsed power sources). This multistage "one-to-one transformer" configuration with non-resonant, low impedance induction cells accelerates kilo-Ampere-scale electron beam current pulses in induction linacs.

Beam breakup in an advanced linear induction accelerator

DOE PAGES

Ekdahl, Carl August; Coleman, Joshua Eugene; McCuistian, Brian Trent

2016-07-01

Two linear induction accelerators (LIAs) have been in operation for a number of years at the Los Alamos Dual Axis Radiographic Hydrodynamic Test (DARHT) facility. A new multipulse LIA is being developed. We have computationally investigated the beam breakup (BBU) instability in this advanced LIA. In particular, we have explored the consequences of the choice of beam injector energy and the grouping of LIA cells. We find that within the limited range of options presently under consideration for the LIA architecture, there is little adverse effect on the BBU growth. The computational tool that we used for this investigation wasmore » the beam dynamics code linear accelerator model for DARHT (LAMDA). In conclusion, to confirm that LAMDA was appropriate for this task, we first validated it through comparisons with the experimental BBU data acquired on the DARHT accelerators.« less

Motion sickness and otolith sensitivity - A pilot study of habituation to linear acceleration

NASA Technical Reports Server (NTRS)

Potvin, A. R.; Sadoff, M.; Billingham, J.

1977-01-01

Astronauts, particularly in Skylab flights, experienced varying degrees of motion sickness lasting 3-5 days. One possible mechanism for this motion sickness adaptation is believed to be a reduction in otolith sensitivity with an attendant reduction in sensory conflict. In an attempt to determine if this hypothesis is valid, a ground-based pilot study was conducted on a vertical linear accelerator. The extent of habituation to accelerations which initially produced motion sickness was evaluated, along with the possible value of habituation training to minimize the space motion sickness problem. Results showed that habituation occurred for 6 of the 8 subjects tested. However, in tests designed to measure dynamic and static otolith function, no significant differences between pre- and post-habituation tests were observed. Cross habituation effects to a standard Coriolis acceleration test were not significant. It is unlikely that ground-based pre-habituation to linear accelerations of the type examined would alter susceptibility to space motion sickness.

Solar wind speed and He I (1083 nm) absorption line intensity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hakamada, Kazuyuki; Kojima, Masayoshi; Kakinuma, Takakiyo

1991-04-01

Since the pattern of the solar wind was relatively steady during Carrington rotations 1,748 through 1,752 in 1984, an average distribution of the solar windspeed on a so-called source surface can be constructed by superposed epoch analysis of the wind values estimated by the interplanetary scintillation observations. The average distribution of the solar wind speed is then projected onto the photosphere along magnetic field lines computed by a so-called potential model with the line-of-sight components of the photospheric magnetic fields. The solar wind speeds projected onto the photosphere are compared with the intensities of the He I (1,083 nm) absorptionmore » line at the corresponding locations in the chromosphere. The authors found that there is a linear relation between the speeds and the intensities. Since the intensity of the He I (1,083 nm) absorption line is coupled with the temperature of the corona, this relation suggests that some physical mechanism in or above the photosphere accelerates coronal plasmas to the solar wind speed in regions where the temperature is low. Further, it is suggested that the efficiency of the solar wind acceleration decreases as the coronal temperature increases.« less

Microwave and Electron Beam Computer Programs

DTIC Science & Technology

1988-06-01

Research (ONR). SCRIBE was adapted by MRC from the Stanford Linear Accelerator Center Beam Trajectory Program, EGUN . oTIC NSECE Acc !,,o For IDL1C I...achieved with SCRIBE. It is a ver- sion of the Stanford Linear Accelerator (SLAC) code EGUN (Ref. 8), extensively modified by MRC for research on

SOME PROBLEMS IN THE CONSTRUCTION OF AN ELECTRON LINEAR ACCELERATOR (in Dutch)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verhaeghe, J.; Vanhuyse, V.; Van Leuven, P.

1959-01-01

Special problems encountered in the construction of the electron linear accelerator of the Natuurkundig Laboratorium der Rijksuniversiteit of Ghent are discussed. The subjects considered are magnetic focusing, magnetic screening of the electron gun cathode, abnormal attenuation-multipactor effects, and electron energy control. (J.S.R.)

Behind the Scenes of the Spallation Neutron Source – The Linear Accelerator

ScienceCinema

Galambos, John

2018-06-25

The Spallation Neutron Source at Oak Ridge National Laboratory is a one-of-a-kind research facility that provides the most intense pulsed neutron beams in the world for scientific research and industrial development. Take a look inside the facility's linear accelerator.

Radio frequency quadrupole resonator for linear accelerator

DOEpatents

Moretti, Alfred

1985-01-01

An RFQ resonator for a linear accelerator having a reduced level of interfering modes and producing a quadrupole mode for focusing, bunching and accelerating beams of heavy charged particles, with the construction being characterized by four elongated resonating rods within a cylinder with the rods being alternately shorted and open electrically to the shell at common ends of the rods to provide an LC parallel resonant circuit when activated by a magnetic field transverse to the longitudinal axis.

Radio-frequency quadrupole resonator for linear accelerator

DOEpatents

Moretti, A.

1982-10-19

An RFQ resonator for a linear accelerator having a reduced level of interfering modes and producing a quadrupole mode for focusing, bunching and accelerating beams of heavy charged particles, with the construction being characterized by four elongated resonating rods within a cylinder with the rods being alternately shorted and open electrically to the shell at common ends of the rods to provide an LC parallel resonant circuit when activated by a magnetic field transverse to the longitudinal axis.

Vestibular coriolis effect differences modeled with three-dimensional linear-angular interactions.

PubMed

Holly, Jan E

2004-01-01

The vestibular coriolis (or "cross-coupling") effect is traditionally explained by cross-coupled angular vectors, which, however, do not explain the differences in perceptual disturbance under different acceleration conditions. For example, during head roll tilt in a rotating chair, the magnitude of perceptual disturbance is affected by a number of factors, including acceleration or deceleration of the chair rotation or a zero-g environment. Therefore, it has been suggested that linear-angular interactions play a role. The present research investigated whether these perceptual differences and others involving linear coriolis accelerations could be explained under one common framework: the laws of motion in three dimensions, which include all linear-angular interactions among all six components of motion (three angular and three linear). The results show that the three-dimensional laws of motion predict the differences in perceptual disturbance. No special properties of the vestibular system or nervous system are required. In addition, simulations were performed with angular, linear, and tilt time constants inserted into the model, giving the same predictions. Three-dimensional graphics were used to highlight the manner in which linear-angular interaction causes perceptual disturbance, and a crucial component is the Stretch Factor, which measures the "unexpected" linear component.

Hermes 3

NASA Astrophysics Data System (ADS)

Hasti, D. E.; Ramirez, J. J.; Prestwich, K. R.; Sanford, T. W. L.; Hamil, R. A.

Hermes 3 is a major new gamma-ray simulator that is part of the Simulation Technology Laboratory Project. This accelerator will significantly improve the capability to evaluate the effects of gamma-ray radiation from nuclear weapons on weapons subsystems. This accelerator will be designed to produce 10(5)R, 5 x 10 to the 12th power R/S and 2 x 10 to the 20th power R/S(2) over a 500 sq cm area. The radiation dose will vary less than a factor of two over this area and less than a factor of four throughout a volume found by extending this surface 15 cm further from the gamma-ray converter. The minimum dose in this volume will be greater than or equal to 5 x 10 to the 4th power R. The accelerator will be designed with sufficient reliability and short enough turn-around time to produce more than 600 radiation pulses per year. In Hermes 3 the peak power in the beam is to be increased from 1.2 TW of Hermes 2 to 16 TW. Two techniques for achieving these high powers have been successfully developed. The first technique is a high current linear induction accelerator with several parallel beams. Experiments to evaluate this concept were done on the MABE accelerator. The second concept uses induction cavities and a magnetically insulated transmission line (MITL) to form a multi-terawatt voltage adder.

A 10 Billion MeV Cyclotron

ERIC Educational Resources Information Center

Edge, R. D.

1974-01-01

Discusses the design of a device which serves to demonstrate the principle of acceleration and phase stability by accelerating gravitationally a ball bearing along a spiral groove. Application of the design principle to the acceleration aspect of a linear accelerator is recommended. (CC)

Automated ultrafast kilovoltage-megavoltage cone-beam CT for image guided radiotherapy of lung cancer: System description and real-time results.

PubMed

Blessing, Manuel; Arns, Anna; Wertz, Hansjoerg; Stsepankou, Dzmitry; Boda-Heggemann, Judit; Hesser, Juergen; Wenz, Frederik; Lohr, Frank

2018-04-01

To establish a fully automated kV-MV CBCT imaging method on a clinical linear accelerator that allows image acquisition of thoracic targets for patient positioning within one breath-hold (∼15s) under realistic clinical conditions. Our previously developed FPGA-based hardware unit which allows synchronized kV-MV CBCT projection acquisition is connected to a clinical linear accelerator system via a multi-pin switch; i.e. either kV-MV imaging or conventional clinical mode can be selected. An application program was developed to control the relevant linac parameters automatically and to manage the MV detector readout as well as the gantry angle capture for each MV projection. The kV projections are acquired with the conventional CBCT system. GPU-accelerated filtered backprojection is performed separately for both data sets. After appropriate grayscale normalization both modalities are combined and the final kV-MV volume is re-imported in the CBCT system to enable image matching. To demonstrate adequate geometrical accuracy of the novel imaging system the Penta-Guide phantom QA procedure is performed. Furthermore, a human plastinate and different tumor shapes in a thorax phantom are scanned. Diameters of the known tumor shapes are measured in the kV-MV reconstruction. An automated kV-MV CBCT workflow was successfully established in a clinical environment. The overall procedure, from starting the data acquisition until the reconstructed volume is available for registration, requires ∼90s including 17s acquisition time for 100° rotation. It is very simple and allows target positioning in the same way as for conventional CBCT. Registration accuracy of the QA phantom is within ±1mm. The average deviation from the known tumor dimensions measured in the thorax phantom was 0.7mm which corresponds to an improvement of 36% compared to our previous kV-MV imaging system. Due to automation the kV-MV CBCT workflow is speeded up by a factor of >10 compared to the manual approach. Thus, the system allows a simple, fast and reliable imaging procedure and fulfills all requirements to be successfully introduced into the clinical workflow now, enabling single-breath-hold volume imaging. Copyright © 2018. Published by Elsevier GmbH.

Beam-driven acceleration in ultra-dense plasma media

DOE PAGES

Shin, Young-Min

2014-09-15

Accelerating parameters of beam-driven wakefield acceleration in an extremely dense plasma column has been analyzed with the dynamic framed particle-in-cell plasma simulator, and compared with analytic calculations. In the model, a witness beam undergoes a TeV/m scale alternating potential gradient excited by a micro-bunched drive beam in a 10 25 m -3 and 1.6 x 10 28 m -3 plasma column. The acceleration gradient, energy gain, and transformer ratio have been extensively studied in quasi-linear, linear-, and blowout-regimes. The simulation analysis indicated that in the beam-driven acceleration system a hollow plasma channel offers 20 % higher acceleration gradient by enlargingmore » the channel radius (r) from 0.2 Ap to 0.6 .Ap in a blowout regime. This paper suggests a feasibility of TeV/m scale acceleration with a hollow crystalline structure (e.g. nanotubes) of high electron plasma density.« less

The MRI-Linear Accelerator Consortium: Evidence-Based Clinical Introduction of an Innovation in Radiation Oncology Connecting Researchers, Methodology, Data Collection, Quality Assurance, and Technical Development.

PubMed

Kerkmeijer, Linda G W; Fuller, Clifton D; Verkooijen, Helena M; Verheij, Marcel; Choudhury, Ananya; Harrington, Kevin J; Schultz, Chris; Sahgal, Arjun; Frank, Steven J; Goldwein, Joel; Brown, Kevin J; Minsky, Bruce D; van Vulpen, Marco

2016-01-01

An international research consortium has been formed to facilitate evidence-based introduction of MR-guided radiotherapy (MR-linac) and to address how the MR-linac could be used to achieve an optimized radiation treatment approach to improve patients' survival, local, and regional tumor control and quality of life. The present paper describes the organizational structure of the clinical part of the MR-linac consortium. Furthermore, it elucidates why collaboration on this large project is necessary, and how a central data registry program will be implemented.

On the Convergence of an Implicitly Restarted Arnoldi Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lehoucq, Richard B.

We show that Sorensen's [35] implicitly restarted Arnoldi method (including its block extension) is simultaneous iteration with an implicit projection step to accelerate convergence to the invariant subspace of interest. By using the geometric convergence theory for simultaneous iteration due to Watkins and Elsner [43], we prove that an implicitly restarted Arnoldi method can achieve a super-linear rate of convergence to the dominant invariant subspace of a matrix. Moreover, we show how an IRAM computes a nested sequence of approximations for the partial Schur decomposition associated with the dominant invariant subspace of a matrix.

A General Algorithm for Reusing Krylov Subspace Information. I. Unsteady Navier-Stokes

NASA Technical Reports Server (NTRS)

Carpenter, Mark H.; Vuik, C.; Lucas, Peter; vanGijzen, Martin; Bijl, Hester

2010-01-01

A general algorithm is developed that reuses available information to accelerate the iterative convergence of linear systems with multiple right-hand sides A x = b (sup i), which are commonly encountered in steady or unsteady simulations of nonlinear equations. The algorithm is based on the classical GMRES algorithm with eigenvector enrichment but also includes a Galerkin projection preprocessing step and several novel Krylov subspace reuse strategies. The new approach is applied to a set of test problems, including an unsteady turbulent airfoil, and is shown in some cases to provide significant improvement in computational efficiency relative to baseline approaches.

The adequate stimulus for avian short latency vestibular responses to linear translation

NASA Technical Reports Server (NTRS)

Jones, T. A.; Jones, S. M.; Colbert, S.

1998-01-01

Transient linear acceleration stimuli have been shown to elicit eighth nerve vestibular compound action potentials in birds and mammals. The present study was undertaken to better define the nature of the adequate stimulus for neurons generating the response in the chicken (Gallus domesticus). In particular, the study evaluated the question of whether the neurons studied are most sensitive to the maximum level of linear acceleration achieved or to the rate of change in acceleration (da/dt, or jerk). To do this, vestibular response thresholds were measured as a function of stimulus onset slope. Traditional computer signal averaging was used to record responses to pulsed linear acceleration stimuli. Stimulus onset slope was systematically varied. Acceleration thresholds decreased with increasing stimulus onset slope (decreasing stimulus rise time). When stimuli were expressed in units of jerk (g/ms), thresholds were virtually constant for all stimulus rise times. Moreover, stimuli having identical jerk magnitudes but widely varying peak acceleration levels produced virtually identical responses. Vestibular response thresholds, latencies and amplitudes appear to be determined strictly by stimulus jerk magnitudes. Stimulus attributes such as peak acceleration or rise time alone do not provide sufficient information to predict response parameter quantities. Indeed, the major response parameters were shown to be virtually independent of peak acceleration levels or rise time when these stimulus features were isolated and considered separately. It is concluded that the neurons generating short latency vestibular evoked potentials do so as "jerk encoders" in the chicken. Primary afferents classified as "irregular", and which traditionally fall into the broad category of "dynamic" or "phasic" neurons, would seem to be the most likely candidates for the neural generators of short latency vestibular compound action potentials.

Influence of tungsten fiber’s slow drift on the measurement of G with angular acceleration method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Jie; Wu, Wei-Huang; Zhan, Wen-Ze

In the measurement of the gravitational constant G with angular acceleration method, the equilibrium position of torsion pendulum with tungsten fiber undergoes a linear slow drift, which results in a quadratic slow drift on the angular velocity of the torsion balance turntable under feedback control unit. The accurate amplitude determination of the useful angular acceleration signal with known frequency is biased by the linear slow drift and the coupling effect of the drifting equilibrium position and the room fixed gravitational background signal. We calculate the influences of the linear slow drift and the complex coupling effect on the value ofmore » G, respectively. The result shows that the bias of the linear slow drift on G is 7 ppm, and the influence of the coupling effect is less than 1 ppm.« less

Influence of tungsten fiber's slow drift on the measurement of G with angular acceleration method.

PubMed

Luo, Jie; Wu, Wei-Huang; Xue, Chao; Shao, Cheng-Gang; Zhan, Wen-Ze; Wu, Jun-Fei; Milyukov, Vadim

2016-08-01

In the measurement of the gravitational constant G with angular acceleration method, the equilibrium position of torsion pendulum with tungsten fiber undergoes a linear slow drift, which results in a quadratic slow drift on the angular velocity of the torsion balance turntable under feedback control unit. The accurate amplitude determination of the useful angular acceleration signal with known frequency is biased by the linear slow drift and the coupling effect of the drifting equilibrium position and the room fixed gravitational background signal. We calculate the influences of the linear slow drift and the complex coupling effect on the value of G, respectively. The result shows that the bias of the linear slow drift on G is 7 ppm, and the influence of the coupling effect is less than 1 ppm.

Influence of tungsten fiber's slow drift on the measurement of G with angular acceleration method

NASA Astrophysics Data System (ADS)

Luo, Jie; Wu, Wei-Huang; Xue, Chao; Shao, Cheng-Gang; Zhan, Wen-Ze; Wu, Jun-Fei; Milyukov, Vadim

2016-08-01

In the measurement of the gravitational constant G with angular acceleration method, the equilibrium position of torsion pendulum with tungsten fiber undergoes a linear slow drift, which results in a quadratic slow drift on the angular velocity of the torsion balance turntable under feedback control unit. The accurate amplitude determination of the useful angular acceleration signal with known frequency is biased by the linear slow drift and the coupling effect of the drifting equilibrium position and the room fixed gravitational background signal. We calculate the influences of the linear slow drift and the complex coupling effect on the value of G, respectively. The result shows that the bias of the linear slow drift on G is 7 ppm, and the influence of the coupling effect is less than 1 ppm.

Equivalent-Groups versus Single-Group Equating Designs for the Accelerated CAT-ASVAB (Computerized Adaptive Test-Armed Services Vocational Aptitude Battery) Project.

DTIC Science & Technology

1987-01-01

DESIGNS FOR THE ACCELERATED CAT -ASVAB * PROJECT Peter H. Stoloff DTIC’- , " SELECTE -NOV 2 3 987 A Division of Hudson Institute CENTER FOR NAVAL ANALYSES...65153M C0031 SI TITLE (Include Security Classification) Equivalent-Groups Versus Single-Group Equating Designs For The Accelerated CAT -ASVAB Project...GROUP ACAP (Accelerated CAT -ASVAB Program), Aptitude tests, ASVAB (Armed 05 10 Services Vocational Aptitude Battery), CAT (Computerized Adaptive Test

Commnity Petascale Project for Accelerator Science And Simulation: Advancing Computational Science for Future Accelerators And Accelerator Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spentzouris, Panagiotis; /Fermilab; Cary, John

The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessarymore » accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.« less

Advanced Accelerators: Particle, Photon and Plasma Wave Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Ronald L.

2017-06-29

The overall objective of this project was to study the acceleration of electrons to very high energies over very short distances based on trapping slowly moving electrons in the fast moving potential wells of large amplitude plasma waves, which have relativistic phase velocities. These relativistic plasma waves, or wakefields, are the basis of table-top accelerators that have been shown to accelerate electrons to the same high energies as kilometer-length linear particle colliders operating using traditional decades-old acceleration techniques. The accelerating electrostatic fields of the relativistic plasma wave accelerators can be as large as GigaVolts/meter, and our goal was to studymore » techniques for remotely measuring these large fields by injecting low energy probe electron beams across the plasma wave and measuring the beam’s deflection. Our method of study was via computer simulations, and these results suggested that the deflection of the probe electron beam was directly proportional to the amplitude of the plasma wave. This is the basis of a proposed diagnostic technique, and numerous studies were performed to determine the effects of changing the electron beam, plasma wave and laser beam parameters. Further simulation studies included copropagating laser beams with the relativistic plasma waves. New interesting results came out of these studies including the prediction that very small scale electron beam bunching occurs, and an anomalous line focusing of the electron beam occurs under certain conditions. These studies were summarized in the dissertation of a graduate student who obtained the Ph.D. in physics. This past research program has motivated ideas for further research to corroborate these results using particle-in-cell simulation tools which will help design a test-of-concept experiment in our laboratory and a scaled up version for testing at a major wakefield accelerator facility.« less

Calculations of beam dynamics in Sandia linear electron accelerators, 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poukey, J.W.; Coleman, P.D.

1985-03-01

A number of code and analytic studies were made during 1984 which pertain to the Sandia linear accelerators MABE and RADLAC. In this report the authors summarize the important results of the calculations. New results include a better understanding of gap-induced radial oscillations, leakage currents in a typical MABE gas, emittance growth in a beam passing through a series of gaps, some new diocotron results, and the latest diode simulations for both accelerators. 23 references, 30 figures, 1 table.

Astronaut mass measurement using linear acceleration method and the effect of body non-rigidity

NASA Astrophysics Data System (ADS)

Yan, Hui; Li, LuMing; Hu, ChunHua; Chen, Hao; Hao, HongWei

2011-04-01

Astronaut's body mass is an essential factor of health monitoring in space. The latest mass measurement device for the International Space Station (ISS) has employed a linear acceleration method. The principle of this method is that the device generates a constant pulling force, and the astronaut is accelerated on a parallelogram motion guide which rotates at a large radius to achieve a nearly linear trajectory. The acceleration is calculated by regression analysis of the displacement versus time trajectory and the body mass is calculated by using the formula m= F/ a. However, in actual flight, the device is instable that the deviation between runs could be 6-7 kg. This paper considers the body non-rigidity as the major cause of error and instability and analyzes the effects of body non-rigidity from different aspects. Body non-rigidity makes the acceleration of the center of mass (C.M.) oscillate and fall behind the point where force is applied. Actual acceleration curves showed that the overall effect of body non-rigidity is an oscillation at about 7 Hz and a deviation of about 25%. To enhance body rigidity, better body restraints were introduced and a prototype based on linear acceleration method was built. Measurement experiment was carried out on ground on an air table. Three human subjects weighing 60-70 kg were measured. The average variance was 0.04 kg and the average measurement error was 0.4%. This study will provide reference for future development of China's own mass measurement device.

Reinventing the Accelerator for the High Energy Frontier

ScienceCinema

Rosenzweig, James [UCLA, Los Angeles, California, United States

2017-12-09

The history of discovery in high-energy physics has been intimately connected with progress in methods of accelerating particles for the past 75 years. This remains true today, as the post-LHC era in particle physics will require significant innovation and investment in a superconducting linear collider. The choice of the linear collider as the next-generation discovery machine, and the selection of superconducting technology has rather suddenly thrown promising competing techniques -- such as very large hadron colliders, muon colliders, and high-field, high frequency linear colliders -- into the background. We discuss the state of such conventional options, and the likelihood of their eventual success. We then follow with a much longer view: a survey of a new, burgeoning frontier in high energy accelerators, where intense lasers, charged particle beams, and plasmas are all combined in a cross-disciplinary effort to reinvent the accelerator from its fundamental principles on up.

Recording the synchrotron radiation by a picosecond streak camera for bunch diagnostics in cyclic accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vereshchagin, A K; Vorob'ev, N S; Gornostaev, P B

2016-02-28

A PS-1/S1 picosecond streak camera with a linear sweep is used to measure temporal characteristics of synchrotron radiation pulses on a damping ring (DR) at the Budker Institute of Nuclear Physics (BINP) of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk). The data obtained allow a conclusion as to the formation processes of electron bunches and their 'quality' in the DR after injection from the linear accelerator. The expediency of employing the streak camera as a part of an optical diagnostic accelerator complex for adjusting the injection from a linear accelerator is shown. Discussed is the issue ofmore » designing a new-generation dissector with a time resolution up to a few picoseconds, which would allow implementation of a continuous bunch monitoring in the DR during mutual work with the electron-positron colliders at the BINP. (acoustooptics)« less

Initial Human Response to Nuclear Radiation

DTIC Science & Technology

1982-04-01

radiation from a linear accelerator . Victim A , age 31, received a dose of 100 rads; victim B, age 29... The radiation has always been in the million-electron- volt range, usually from a cobalt 60 source but sometimes using linear accelerators prouucing up...more recent medical experience, Appendix B presents comments by a radiation oncologist on the

Indirectly sensing accelerator beam currents for limiting maximum beam current magnitude

DOEpatents

Bogaty, J.M.; Clifft, B.E.; Bollinger, L.M.

1995-08-08

A beam current limiter is disclosed for sensing and limiting the beam current in a particle accelerator, such as a cyclotron or linear accelerator, used in scientific research and medical treatment. A pair of independently operable capacitive electrodes sense the passage of charged particle bunches to develop an RF signal indicative of the beam current magnitude produced at the output of a bunched beam accelerator. The RF signal produced by each sensing electrode is converted to a variable DC voltage indicative of the beam current magnitude. The variable DC voltages thus developed are compared to each other to verify proper system function and are further compared to known references to detect beam currents in excess of pre-established limits. In the event of a system malfunction, or if the detected beam current exceeds pre-established limits, the beam current limiter automatically inhibits further accelerator operation. A high Q tank circuit associated with each sensing electrode provides a narrow system bandwidth to reduce noise and enhance dynamic range. System linearity is provided by injecting, into each sensing electrode, an RF signal that is offset from the bunching frequency by a pre-determined beat frequency to ensure that subsequent rectifying diodes operate in a linear response region. The system thus provides a large dynamic range in combination with good linearity. 6 figs.

Indirectly sensing accelerator beam currents for limiting maximum beam current magnitude

DOEpatents

Bogaty, John M.; Clifft, Benny E.; Bollinger, Lowell M.

1995-01-01

A beam current limiter for sensing and limiting the beam current in a particle accelerator, such as a cyclotron or linear accelerator, used in scientific research and medical treatment. A pair of independently operable capacitive electrodes sense the passage of charged particle bunches to develop an RF signal indicative of the beam current magnitude produced at the output of a bunched beam accelerator. The RF signal produced by each sensing electrode is converted to a variable DC voltage indicative of the beam current magnitude. The variable DC voltages thus developed are compared to each other to verify proper system function and are further compared to known references to detect beam currents in excess of pre-established limits. In the event of a system malfunction, or if the detected beam current exceeds pre-established limits, the beam current limiter automatically inhibits further accelerator operation. A high Q tank circuit associated with each sensing electrode provides a narrow system bandwidth to reduce noise and enhance dynamic range. System linearity is provided by injecting, into each sensing electrode, an RF signal that is offset from the bunching frequency by a pre-determined beat frequency to ensure that subsequent rectifying diodes operate in a linear response region. The system thus provides a large dynamic range in combination with good linearity.

Distributed coupling high efficiency linear accelerator

DOEpatents

Tantawi, Sami G.; Neilson, Jeffrey

2016-07-19

A microwave circuit for a linear accelerator includes multiple monolithic metallic cell plates stacked upon each other so that the beam axis passes vertically through a central acceleration cavity of each plate. Each plate has a directional coupler with coupling arms. A first coupling slot couples the directional coupler to an adjacent directional coupler of an adjacent cell plate, and a second coupling slot couples the directional coupler to the central acceleration cavity. Each directional coupler also has an iris protrusion spaced from corners joining the arms, a convex rounded corner at a first corner joining the arms, and a corner protrusion at a second corner joining the arms.

Free electron laser

DOEpatents

Villa, Francesco

1990-01-01

A high gain, single-pass free electron laser formed of a high brilliance electron injector source, a linear accelerator which imparts high energy to the electron beam, and an undulator capable of extremely high magnetic fields, yet with a very short period. The electron injector source is the first stage (gap) of the linear accelerator or a radial line transformer driven by fast circular switch. The linear accelerator is formed of a plurality of accelerating gaps arranged in series. These gaps are energized in sequence by releasing a single pulse of energy which propagates simultaneously along a plurality of transmission lines, each of which feeds the gaps. The transmission lines are graduated in length so that pulse power is present at each gap as the accelerated electrons pass therethrough. The transmission lines for each gap are open circuited at their ends. The undualtor has a structure similar to the accelerator, except that the transmission lines for each gap are substantially short circuited at their ends, thus converting the electric field into magnetic field. A small amount of resistance is retained in order to generate a small electric field for replenishing the electron bunch with the energy lost as it traverses through the undulator structure.

TU-H-BRA-01: The Physics of High Power Radiofrequency Isolation in a Novel Compact Linear Accelerator Based MRI Guided Radiation Therapy System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamb, J; Low, D; Mutic, S

Purpose: To develop a method for isolating the radiofrequency waves emanating from linear accelerator components from the magnetic resonance imaging (MRI) system of an integrated MRI-linac. Methods: An MRI-guided radiation therapy system has been designed that integrates a linear accelerator with simultaneous MR imaging. The radiofrequency waves created by the accelerating process would degrade MR image quality, so a method for containing the radiofrequency waves and isolating the MR imager from them was developed. The linear accelerator radiofrequency modulator was placed outside the room, so a filter was designed to eliminate the radiofrequency corresponding to the proton Larmour frequency ofmore » 14.7 MHz. Placing the radiofrequency emitting components in a typical Faraday cage would have reduced the radiofrequency emissions, but the design would be susceptible to small gaps in the shield due to the efficiency of the Faraday cage reflecting internal radiofrequency emissions. To reduce internal radiofrequency reflections, the Faraday cage was lined with carbon fiber sheets. Carbon fiber has the property of attenuating the radiofrequency energy so that the overall radiofrequency field inside the Faraday cage is reduced, decreasing any radiofrequency energy emitted from small gaps in the cage walls. Results: Within a 1.2 MHz band centered on the Larmor frequency, the radiofrequency (RF) leakage from the Faraday cage was measured to be −90 dB with no RF on, −40 dB with the RF on and no shield, returning to −90 dB with the RF on and shields in place. The radiofrequency filter attenuated the linear accelerator modulator emissions in the 14.7 MHz band by 70 dB. Conclusions: One of the major challenges in designing a compact linear accelerator based MRI-guided radiation therapy system, that of isolating the high power RF system from the MRI, has been solved. The measured radiofrequency emissions are sufficiently small to enable system integration. This research was funded by ViewRay, Inc., Oakwood, OH.« less

TU-H-BRA-02: The Physics of Magnetic Field Isolation in a Novel Compact Linear Accelerator Based MRI-Guided Radiation Therapy System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Low, D; Mutic, S; Shvartsman, S

Purpose: To develop a method for isolating the MRI magnetic field from field-sensitive linear accelerator components at distances close to isocenter. Methods: A MRI-guided radiation therapy system has been designed that integrates a linear accelerator with simultaneous MR imaging. In order to accomplish this, the magnetron, port circulator, radiofrequency waveguide, gun driver, and linear accelerator needed to be placed in locations with low magnetic fields. The system was also required to be compact, so moving these components far from the main magnetic field and isocenter was not an option. The magnetic field sensitive components (exclusive of the waveguide) were placedmore » in coaxial steel sleeves that were electrically and mechanically isolated and whose thickness and placement were optimized using E&M modeling software. Six sets of sleeves were placed 60° apart, 85 cm from isocenter. The Faraday effect occurs when the direction of propagation is parallel to the magnetic RF field component, rotating the RF polarization, subsequently diminishing RF power. The Faraday effect was avoided by orienting the waveguides such that the magnetic field RF component was parallel to the magnetic field. Results: The magnetic field within the shields was measured to be less than 40 Gauss, significantly below the amount needed for the magnetron and port circulator. Additional mu-metal was employed to reduce the magnetic field at the linear accelerator to less than 1 Gauss. The orientation of the RF waveguides allowed the RT transport with minimal loss and reflection. Conclusion: One of the major challenges in designing a compact linear accelerator based MRI-guided radiation therapy system, that of creating low magnetic field environments for the magnetic-field sensitive components, has been solved. The measured magnetic fields are sufficiently small to enable system integration. This work supported by ViewRay, Inc.« less

Detection of linear ego-acceleration from optic flow.

PubMed

Festl, Freya; Recktenwald, Fabian; Yuan, Chunrong; Mallot, Hanspeter A

2012-07-20

Human observers are able to estimate various ego-motion parameters from optic flow, including rotation, translational heading, time-to-collision (TTC), time-to-passage (TTP), etc. The perception of linear ego-acceleration or deceleration, i.e., changes of translational velocity, is less well understood. While time-to-passage experiments indicate that ego-acceleration is neglected, subjects are able to keep their (perceived) speed constant under changing conditions, indicating that some sense of ego-acceleration or velocity change must be present. In this paper, we analyze the relation of ego-acceleration estimates and geometrical parameters of the environment using simulated flights through cylindrical and conic (narrowing or widening) corridors. Theoretical analysis shows that a logarithmic ego-acceleration parameter, called the acceleration rate ρ, can be calculated from retinal acceleration measurements. This parameter is independent of the geometrical layout of the scene; if veridical ego-motion is known at some instant in time, acceleration rate allows updating of ego-motion without further depth-velocity calibration. Results indicate, however, that subjects systematically confuse ego-acceleration with corridor narrowing and ego-deceleration with corridor widening, while veridically judging ego-acceleration in straight corridors. We conclude that judgments of ego-acceleration are based on first-order retinal flow and do not make use of acceleration rate or retinal acceleration.

Accelerated testing for studying pavement design and performance (FY 2002) : research summary.

DOT National Transportation Integrated Search

2004-01-01

This report covers the Fiscal Year 2002 project conducted at the Accelerated Testing : Laboratory at Kansas State University. The project was selected and funded by the : Midwest States Accelerated Testing Pooled Fund Program, which includes Iowa, Ka...

Heating and Acceleration of Charged Particles by Weakly Compressible Magnetohydrodynamic Turbulence

NASA Astrophysics Data System (ADS)

Lynn, Jacob William

We investigate the interaction between low-frequency magnetohydrodynamic (MHD) turbulence and a distribution of charged particles. Understanding this physics is central to understanding the heating of the solar wind, as well as the heating and acceleration of other collisionless plasmas. Our central method is to simulate weakly compressible MHD turbulence using the Athena code, along with a distribution of test particles which feel the electromagnetic fields of the turbulence. We also construct analytic models of transit-time damping (TTD), which results from the mirror force caused by compressible (fast or slow) MHD waves. Standard linear-theory models in the literature require an exact resonance between particle and wave velocities to accelerate particles. The models developed in this thesis go beyond standard linear theory to account for the fact that wave-particle interactions decorrelate over a short time, which allows particles with velocities off resonance to undergo acceleration and velocity diffusion. We use the test particle simulation results to calibrate and distinguish between different models for this velocity diffusion. Test particle heating is larger than the linear theory prediction, due to continued acceleration of particles with velocities off-resonance. We also include an artificial pitch-angle scattering to the test particle motion, representing the effect of high-frequency waves or velocity-space instabilities. For low scattering rates, we find that the scattering enforces isotropy and enhances heating by a modest factor. For much higher scattering rates, the acceleration is instead due to a non-resonant effect, as particles "frozen" into the fluid adiabatically gain and lose energy as eddies expand and contract. Lastly, we generalize our calculations to allow for relativistic test particles. Linear theory predicts that relativistic particles with velocities much higher than the speed of waves comprising the turbulence would undergo no acceleration; resonance-broadening modifies this conclusion and allows for a continued Fermi-like acceleration process. This may affect the observed spectra of black hole accretion disks by accelerating relativistic particles into a quasi-powerlaw tail.

Development work for a superconducting linear collider

NASA Technical Reports Server (NTRS)

Matheisen, Axel

1995-01-01

For future linear e(+)e(-) colliders in the TeV range several alternatives are under discussion. The TESLA approach is based on the advantages of superconductivity. High Q values of the accelerator structures give high efficiency for converting RF power into beam power. A low resonance frequency for the RF structures can be chosen to obtain a large number of electrons (positrons) per bunch. For a given luminosity the beam dimensions can be chosen conservatively which leads to relaxed beam emittance and tolerances at the final focus. Each individual superconducting accelerator component (resonator cavity) of this linear collider has to deliver an energy gain of 25 MeV/m to the beam. Today s.c. resonators are in use at CEBAF/USA, at DESY/Germany, Darmstadt/Germany KEK/Japan and CERN/Geneva. They show acceleration gradients between 5 MV/m and 10 MV/m. Encouraging experiments at CEA Saclay and Cornell University showed acceleration gradients of 20 MV/m and 25 MV/m in single and multicell structures. In an activity centered at DESY in Hamburg/Germany the TESLA collaboration is constructing a 500 MeV superconducting accelerator test facility (TTF) to demonstrate that a linear collider based on this technique can be built in a cost effective manner and that the necessary acceleration gradients of more than 15 MeV/m can be reached reproducibly. The test facility built at DESY covers an area of 3.000 m2 and is divided into 3 major activity areas: (1) The testlinac, where the performance ofthe modular components with an electron beam passing the 40 m long acceleration section can be demonstrated. (2) The test area, where all individual resonators are tested before installation into a module. (3) The preparation and assembly area, where assembly of cavities and modules take place. We report here on the design work to reach a reduction of costs compared to actual existing superconducting accelerator structures and on the facility set up to reach high acceleration gradients in a reproducible way.

Numerical algorithms for scatter-to-attenuation reconstruction in PET: empirical comparison of convergence, acceleration, and the effect of subsets.

PubMed

Berker, Yannick; Karp, Joel S; Schulz, Volkmar

2017-09-01

The use of scattered coincidences for attenuation correction of positron emission tomography (PET) data has recently been proposed. For practical applications, convergence speeds require further improvement, yet there exists a trade-off between convergence speed and the risk of non-convergence. In this respect, a maximum-likelihood gradient-ascent (MLGA) algorithm and a two-branch back-projection (2BP), which was previously proposed, were evaluated. MLGA was combined with the Armijo step size rule; and accelerated using conjugate gradients, Nesterov's momentum method, and data subsets of different sizes. In 2BP, we varied the subset size, an important determinant of convergence speed and computational burden. We used three sets of simulation data to evaluate the impact of a spatial scale factor. The Armijo step size allowed 10-fold increased step sizes compared to native MLGA. Conjugate gradients and Nesterov momentum lead to slightly faster, yet non-uniform convergence; improvements were mostly confined to later iterations, possibly due to the non-linearity of the problem. MLGA with data subsets achieved faster, uniform, and predictable convergence, with a speed-up factor equivalent to the number of subsets and no increase in computational burden. By contrast, 2BP computational burden increased linearly with the number of subsets due to repeated evaluation of the objective function, and convergence was limited to the case of many (and therefore small) subsets, which resulted in high computational burden. Possibilities of improving 2BP appear limited. While general-purpose acceleration methods appear insufficient for MLGA, results suggest that data subsets are a promising way of improving MLGA performance.

Vestibular afferent responses to linear accelerations in the alert squirrel monkey

NASA Technical Reports Server (NTRS)

Somps, Christopher J.; Schor, Robert H.; Tomko, David L.

1994-01-01

The spontaneous activity of 40 otolith afferents and 44 canal afferents was recorded in 4 alert, intact squirrel monkeys. Polarization vectors and response properties of otolith afferents were determined during static re-orientations relative to gravity and during Earth-horizontal, sinusoidal, linear oscillations. Canal afferents were tested for sensitivity to linear accelerations. For regular otolith afferents, a significant correlation between upright discharge rate and sensitivity to dynamic acceleration in the horizontal plane was observed. This correlation was not present in irregular units. The sensitivity of otolith afferents to both static tilts and dynamic linear acceleration was much greater in irregularly discharging units than in regularly discharging units. The spontaneous activity and static and dynamic response properties of regularly discharging otolith afferents were similar to those reported in barbiturate-anesthetized squirrel monkeys. Irregular afferents also had similar dynamic response properties when compared to anesthetized monkeys. However, this sample of irregular afferents in alert animals had higher resting discharge rates and greater sensitivity to static tilts. The majority of otolith polarization vectors were oriented near the horizontal in the plane of the utricular maculae; however, directions of maximum sensitivity were different during dynamic and static testing. Canal afferents were not sensitive to static tilts or linear oscillations of the head.

Spatiotemporal processing of linear acceleration: primary afferent and central vestibular neuron responses

NASA Technical Reports Server (NTRS)

Angelaki, D. E.; Dickman, J. D.

2000-01-01

Spatiotemporal convergence and two-dimensional (2-D) neural tuning have been proposed as a major neural mechanism in the signal processing of linear acceleration. To examine this hypothesis, we studied the firing properties of primary otolith afferents and central otolith neurons that respond exclusively to horizontal linear accelerations of the head (0.16-10 Hz) in alert rhesus monkeys. Unlike primary afferents, the majority of central otolith neurons exhibited 2-D spatial tuning to linear acceleration. As a result, central otolith dynamics vary as a function of movement direction. During movement along the maximum sensitivity direction, the dynamics of all central otolith neurons differed significantly from those observed for the primary afferent population. Specifically at low frequencies (

Low-dose megavoltage cone-beam computed tomography for lung tumors using a high-efficiency image receptor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sillanpaa, Jussi; Chang Jenghwa; Mageras, Gikas

2006-09-15

We report on the capabilities of a low-dose megavoltage cone-beam computed tomography (MV CBCT) system. The high-efficiency image receptor consists of a photodiode array coupled to a scintillator composed of individual CsI crystals. The CBCT system uses the 6 MV beam from a linear accelerator. A synchronization circuit allows us to limit the exposure to one beam pulse [0.028 monitor units (MU)] per projection image. 150-500 images (4.2-13.9 MU total) are collected during a one-minute scan and reconstructed using a filtered backprojection algorithm. Anthropomorphic and contrast phantoms are imaged and the contrast-to-noise ratio of the reconstruction is studied as amore » function of the number of projections and the error in the projection angles. The detector dose response is linear (R{sup 2} value 0.9989). A 2% electron density difference is discernible using 460 projection images and a total exposure of 13 MU (corresponding to a maximum absorbed dose of about 12 cGy in a patient). We present first patient images acquired with this system. Tumors in lung are clearly visible and skeletal anatomy is observed in sufficient detail to allow reproducible registration with the planning kV CT images. The MV CBCT system is shown to be capable of obtaining good quality three-dimensional reconstructions at relatively low dose and to be clinically usable for improving the accuracy of radiotherapy patient positioning.« less

Accelerator and Fusion Research Division. Annual report, October 1978-September 1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1980-03-01

Topics covered include: Super HILAC and Bevalac operations; high intensity uranium beams line item; advanced high charge state ion source; 184-inch synchrocyclotron; VENUS project; positron-electron project; high field superconducting accelerator magnets; beam cooling; accelerator theory; induction linac drivers; RF linacs and storage rings; theory; neutral beam systems development; experimental atomic physics; neutral beam plasma research; plasma theory; and the Tormac project. (GHT)

Symposium on electron linear accelerators in honor of Richard B. Neal's 80th birthday: Proceedings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siemann, R.H.

The papers presented at the conference are: (1) the construction of SLAC and the role of R.B. Neal; (2) symposium speech; (3) lessons learned from the SLC; (4) alternate approaches to future electron-positron linear colliders; (5) the NLC technical program; (6) advanced electron linacs; (7) medical uses of linear accelerators; (8) linac-based, intense, coherent X-ray source using self-amplified spontaneous emission. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

Spin dynamics in storage rings and linear accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Irwin, J.

1994-12-01

The purpose of these lectures is to survey the subject of spin dynamics in accelerators: to give a sense of the underlying physics, the typical analytic and numeric methods used, and an overview of results achieved. Consideration will be limited to electrons and protons. Examples of experimental and theoretical results in both linear and circular machines are included.

Finite element analyses of a linear-accelerator electron gun

NASA Astrophysics Data System (ADS)

Iqbal, M.; Wasy, A.; Islam, G. U.; Zhou, Z.

2014-02-01

Thermo-structural analyses of the Beijing Electron-Positron Collider (BEPCII) linear-accelerator, electron gun, were performed for the gun operating with the cathode at 1000 °C. The gun was modeled in computer aided three-dimensional interactive application for finite element analyses through ANSYS workbench. This was followed by simulations using the SLAC electron beam trajectory program EGUN for beam optics analyses. The simulations were compared with experimental results of the assembly to verify its beam parameters under the same boundary conditions. Simulation and test results were found to be in good agreement and hence confirmed the design parameters under the defined operating temperature. The gun is operating continuously since commissioning without any thermal induced failures for the BEPCII linear accelerator.

Finite element analyses of a linear-accelerator electron gun.

PubMed

Iqbal, M; Wasy, A; Islam, G U; Zhou, Z

2014-02-01

Thermo-structural analyses of the Beijing Electron-Positron Collider (BEPCII) linear-accelerator, electron gun, were performed for the gun operating with the cathode at 1000 °C. The gun was modeled in computer aided three-dimensional interactive application for finite element analyses through ANSYS workbench. This was followed by simulations using the SLAC electron beam trajectory program EGUN for beam optics analyses. The simulations were compared with experimental results of the assembly to verify its beam parameters under the same boundary conditions. Simulation and test results were found to be in good agreement and hence confirmed the design parameters under the defined operating temperature. The gun is operating continuously since commissioning without any thermal induced failures for the BEPCII linear accelerator.

Evidence for an elastic projection mechanism in the chameleon tongue.

PubMed Central

de Groot, Jurriaan H.; van Leeuwen, Johan L.

2004-01-01

To capture prey, chameleons ballistically project their tongues as far as 1.5 body lengths with accelerations of up to 500 m s(-2). At the core of a chameleon's tongue is a cylindrical tongue skeleton surrounded by the accelerator muscle. Previously, the cylindrical accelerator muscle was assumed to power tongue projection directly during the actual fast projection of the tongue. However, high-speed recordings of Chamaeleo melleri and C. pardalis reveal that peak powers of 3000 W kg(-1) are necessary to generate the observed accelerations, which exceed the accelerator muscle's capacity by at least five- to 10-fold. Extrinsic structures might power projection via the tongue skeleton. High-speed fluoroscopy suggests that they contribute less than 10% of the required peak instantaneous power. Thus, the projection power must be generated predominantly within the tongue, and an energy-storage-and-release mechanism must be at work. The key structure in the projection mechanism is probably a cylindrical connective-tissue layer, which surrounds the entoglossal process and was previously suggested to act as lubricating tissue. This tissue layer comprises at least 10 sheaths that envelop the entoglossal process. The outer portion connects anteriorly to the accelerator muscle and the inner portion to the retractor structures. The sheaths contain helical arrays of collagen fibres. Prior to projection, the sheaths are longitudinally loaded by the combined radial contraction and hydrostatic lengthening of the accelerator muscle, at an estimated mean power of 144 W kg(-1) in C. melleri. Tongue projection is triggered as the accelerator muscle and the loaded portions of the sheaths start to slide over the tip of the entoglossal process. The springs relax radially while pushing off the rounded tip of the entoglossal process, making the elastic energy stored in the helical fibres available for a simultaneous forward acceleration of the tongue pad, accelerator muscle and retractor structures. The energy release continues as the multilayered spring slides over the tip of the smooth and lubricated entoglossal process. This sliding-spring theory predicts that the sheaths deliver most of the instantaneous power required for tongue projection. The release power of the sliding tubular springs exceeds the work rate of the accelerator muscle by at least a factor of 10 because the elastic-energy release occurs much faster than the loading process. Thus, we have identified a unique catapult mechanism that is very different from standard engineering designs. Our morphological and kinematic observations, as well as the available literature data, are consistent with the proposed mechanism of tongue projection, although experimental tests of the sheath strain and the lubrication of the entoglossal process are currently beyond our technical scope. PMID:15209111

Evidence for an elastic projection mechanism in the chameleon tongue.

PubMed

de Groot, Jurriaan H; van Leeuwen, Johan L

2004-04-07

To capture prey, chameleons ballistically project their tongues as far as 1.5 body lengths with accelerations of up to 500 m s(-2). At the core of a chameleon's tongue is a cylindrical tongue skeleton surrounded by the accelerator muscle. Previously, the cylindrical accelerator muscle was assumed to power tongue projection directly during the actual fast projection of the tongue. However, high-speed recordings of Chamaeleo melleri and C. pardalis reveal that peak powers of 3000 W kg(-1) are necessary to generate the observed accelerations, which exceed the accelerator muscle's capacity by at least five- to 10-fold. Extrinsic structures might power projection via the tongue skeleton. High-speed fluoroscopy suggests that they contribute less than 10% of the required peak instantaneous power. Thus, the projection power must be generated predominantly within the tongue, and an energy-storage-and-release mechanism must be at work. The key structure in the projection mechanism is probably a cylindrical connective-tissue layer, which surrounds the entoglossal process and was previously suggested to act as lubricating tissue. This tissue layer comprises at least 10 sheaths that envelop the entoglossal process. The outer portion connects anteriorly to the accelerator muscle and the inner portion to the retractor structures. The sheaths contain helical arrays of collagen fibres. Prior to projection, the sheaths are longitudinally loaded by the combined radial contraction and hydrostatic lengthening of the accelerator muscle, at an estimated mean power of 144 W kg(-1) in C. melleri. Tongue projection is triggered as the accelerator muscle and the loaded portions of the sheaths start to slide over the tip of the entoglossal process. The springs relax radially while pushing off the rounded tip of the entoglossal process, making the elastic energy stored in the helical fibres available for a simultaneous forward acceleration of the tongue pad, accelerator muscle and retractor structures. The energy release continues as the multilayered spring slides over the tip of the smooth and lubricated entoglossal process. This sliding-spring theory predicts that the sheaths deliver most of the instantaneous power required for tongue projection. The release power of the sliding tubular springs exceeds the work rate of the accelerator muscle by at least a factor of 10 because the elastic-energy release occurs much faster than the loading process. Thus, we have identified a unique catapult mechanism that is very different from standard engineering designs. Our morphological and kinematic observations, as well as the available literature data, are consistent with the proposed mechanism of tongue projection, although experimental tests of the sheath strain and the lubrication of the entoglossal process are currently beyond our technical scope.

Advanced accelerator and mm-wave structure research at LANL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simakov, Evgenya Ivanovna

2016-06-22

This document outlines acceleration projects and mm-wave structure research performed at LANL. The motivation for PBG research is described first, with reference to couplers for superconducting accelerators and structures for room-temperature accelerators and W-band TWTs. These topics are then taken up in greater detail: PBG structures and the MIT PBG accelerator; SRF PBG cavities at LANL; X-band PBG cavities at LANL; and W-band PBG TWT at LANL. The presentation concludes by describing other advanced accelerator projects: beam shaping with an Emittance Exchanger, diamond field emitter array cathodes, and additive manufacturing of novel accelerator structures.

Calibration of a Six-Degree-of-Freedom Acceleration Measurement Device

DOT National Transportation Integrated Search

1994-12-01

This report describes the calibration of a six-degree-of-freedom acceleration measurement system designed for use in the measurement of linear and angular head accelerations of anthropomorphic dummies during crash tests. The calibration methodology, ...

Marshak Lectureship: The Turkish Accelerator Center, TAC

NASA Astrophysics Data System (ADS)

Yavas, Omer

2012-02-01

The Turkish Accelerator Center (TAC) project is comprised of five different electron and proton accelerator complexes, to be built over 15 years, with a phased approach. The Turkish Government funds the project. Currently there are 23 Universities in Turkey associated with the TAC project. The current funded project, which is to run until 2013 aims *To establish a superconducting linac based infra-red free electron laser and Bremsstrahlung Facility (TARLA) at the Golbasi Campus of Ankara University, *To establish the Institute of Accelerator Technologies in Ankara University, and *To complete the Technical Design Report of TAC. The proposed facilities are a 3^rd generation Synchrotron Radiation facility, SASE-FEL facility, a GeV scale Proton Accelerator facility and an electron-positron collider as a super charm factory. In this talk, an overview on the general status and road map of TAC project will be given. National and regional importance of TAC will be expressed and the structure of national and internatonal collaborations will be explained.

[Statocyst regulation of the heart and statokinetic reflexes in the crab, Hemigrapsus sanguineus, during linear acceleration].

PubMed

Kuntsova, M Ia; Sveshnikov, V G; Timofeeva, E V

1978-01-01

In experiments on the shore crab H. sanguineus studies have been made of the effect of variable longitudinal acceleration during swinging (for 15--30 min) upon cardiac activity and gravitational reflexes. High sensitivity of gravitational receptors of the canal statocyst to the effect of acceleration was demonstrated. Removal of the statocysts increases the frequency and amplitude of cardiac contractions as revealed by ECG recording. Changes in stato-kinetic coordinations cause both the disorder of overturning reactions and the disorder of reciprocal inhibition in antagonistic muscles of the dactylopodite. Statocyst regulation of skeletal muscles and heart is presumably realised via contralateral inhibitory canal which is sensitive to linear accelerations.

Individual Impact Magnitude vs. Cumulative Magnitude for Estimating Concussion Odds.

PubMed

O'Connor, Kathryn L; Peeters, Thomas; Szymanski, Stefan; Broglio, Steven P

2017-08-01

Helmeted impact devices have allowed researchers to investigate the biomechanics of head impacts in vivo. While increased impact magnitude has been associated with greater concussion risk, a definitive concussive threshold has not been established. It is likely that concussion risk is not determined by a single impact itself, but a host of predisposing factors. These factors may include genetics, fatigue, and/or prior head impact exposure. The objective of the current paper is to investigate the association between cumulative head impact magnitude and concussion risk. It is hypothesized that increased cumulative magnitudes will be associated with greater concussion risk. This retrospective analysis included participants that were recruited from regional high-schools in Illinois and Michigan from 2007 to 2014 as part of an ongoing study on concussion biomechanics. Across seven seasons, 185 high school football athletes were instrumented with the Head Impact Telemetry system. Out of 185 athletes, 31 (17%) sustained a concussion, with two athletes sustaining two concussions over the study period, yielding 33 concussive events. The system recorded 78,204 impacts for all concussed players. Linear acceleration, rotational acceleration, and head impact telemetry severity profile (HITsp) magnitudes were summed within five timeframes: the day of injury, three days prior to injury, seven days prior to injury, 30 days prior to injury, and prior in-season exposure. Logistic regressions were modeled to explain concussive events based on the singular linear acceleration, rotational acceleration, and HITsp event along with the calculated summations over time. Linear acceleration, rotational acceleration, and HITsp all produced significant models estimating concussion (p < 0.05). The strongest estimators of a concussive impact were the linear acceleration (OR = 1.040, p < 0.05), rotational acceleration (OR = 1.001, p < 0.05), and HITsp (OR = 1.003, p < 0.05) for the singular impact rather than any of the cumulative magnitude calculations. Moreover, no cumulative count measure was significant for linear or rotational acceleration. Results from this investigation support the growing literature indicating cumulative magnitude is not related to concussion likelihood. Cumulative magnitude is a simplistic measure of the total exposure sustained by a player over a given period. However, this measure is limited as it assumes the brain is a static structure unable to undergo self-repair. Future research should consider how biological recovery between impacts may influence concussion risk.

The sense of balance in humans: Structural features of otoconia and their response to linear acceleration

PubMed Central

Kniep, Rüdiger; Zahn, Dirk; Wulfes, Jana

2017-01-01

We explored the functional role of individual otoconia within the otolith system of mammalians responsible for the detection of linear accelerations and head tilts in relation to the gravity vector. Details of the inner structure and the shape of intact human and artificial otoconia were studied using environmental scanning electron microscopy (ESEM), including decalcification by ethylenediaminetetraacetic acid (EDTA) to discriminate local calcium carbonate density. Considerable differences between the rhombohedral faces of human and artificial otoconia already indicate that the inner architecture of otoconia is not consistent with the point group -3m. This is clearly confirmed by decalcified otoconia specimen which are characterized by a non-centrosymmetric volume distribution of the compact 3+3 branches. This structural evidence for asymmetric mass distribution was further supported by light microscopy in combination with a high speed camera showing the movement of single otoconia specimen (artificial specimen) under gravitational influence within a viscous medium (artificial endolymph). Moreover, the response of otoconia to linear acceleration forces was investigated by particle dynamics simulations. Both, time-resolved microscopy and computer simulations of otoconia acceleration show that the dislocation of otoconia include significant rotational movement stemming from density asymmetry. Based on these findings, we suggest an otolith membrane expansion/stiffening mechanism for enhanced response to linear acceleration transmitted to the vestibular hair cells. PMID:28406968

Hermes III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasti, D.E.; Ramirez, J.J.; Prestwich, K.R.

1985-01-01

Hermes III is a major new gamma-ray simulator that is part of the Simulation Technology Laboratory Project. This accelerator will significantly improve the capability of Sandia National Laboratories and the Department of Energy to evaluate the effects of gamma-ray radiation from nuclear weapons on weapons subsystems. This accelerator will be designed to produce 10/sup 5/R, 5 x 10/sup 12/ R/S and 2 x 10/sup 20/ R/S/sup 2/ over a 500 cm/sup 2/ area. The radiation dose will vary less than a factor of two over this area and less than a factor of four throughout a volume found by extendingmore » this surface 15 cm further from the gamma-ray converter. The minimum dose in this volume will be greater than or equal to5 x 10/sup 4/ R. The accelerator will be designed with sufficient reliability and short enough turn-around time to produce more than 600 radiation pulses per year. In Hermes III we are increasing the peak power in the beam from 1.2 TW of Hermes II to 16 TW. Two techniques for achieving these high powers have been successfully developed. The first technique is a high current linear induction accelerator with several parallel beams. Experiments to evaluate this concept were done on the MABE accelerator. The second concept uses induction cavities and a magnetically insulated transmission line (MITL) to form a multi-terawatt voltage adder. This report gives a detailed description of Hermes III and its components.« less

Acceleration of boundary element method for linear elasticity

NASA Astrophysics Data System (ADS)

Zapletal, Jan; Merta, Michal; Čermák, Martin

2017-07-01

In this work we describe the accelerated assembly of system matrices for the boundary element method using the Intel Xeon Phi coprocessors. We present a model problem, provide a brief overview of its discretization and acceleration of the system matrices assembly using the coprocessors, and test the accelerated version using a numerical benchmark.

ARIEL E-linac Cryogenic System: Commissioning and First Operational Experience

NASA Astrophysics Data System (ADS)

Koveshnikov, A.; Bylinskii, I.; Hodgson, G.; Kishi, D.; Laxdal, R.; Ma, Y.; Nagimov, R.; Yosifov, D.

2015-12-01

The Advanced Rare IsotopE Laboratory (ARIEL) is a major expansion of the Isotope Separator and Accelerator (ISAC) facility at TRIUMF. A key part of the ARIEL project is a 10 mA 50 MeV continuous-wave superconducting radiofrequency (SRF) electron linear accelerator (e-linac). The 1.3 GHz SRF cavities are operated at 2 K. HELIAL LL helium liquefier by Air Liquide Advanced Technologies (ALAT) with a tuneable liquid helium (LHe) production was installed and commissioned in Q4’2013 [1]. It provides 4 K liquid helium to one injector and one accelerator cryomodules that were installed and tested in 2014. The 4 K to 2 K liquid helium transition is achieved on-board of each cryomodule. The cryoplant, LHe and LN2 distributions, sub-atmospheric (S/A) system and cryomodules were successfully commissioned and integrated into the e-linac cryogenic system. Required pressure regulation for both 4 K cryoplant in the Dewar and 2 K with the S/A system was achieved under simulated load. Final integration tests confirmed overall stable performance of the cryogenic system with two cryomodules installed. The paper presents details of the cryogenic system commissioning tests as well as highlights of the initial operational experience.

Commissioning of the helium cryogenic system for the HIE- ISOLDE accelerator upgrade at CERN

NASA Astrophysics Data System (ADS)

Delruelle, N.; Inglese, V.; Leclercq, Y.; Pirotte, O.; Williams, L.

2015-12-01

The High Intensity and Energy ISOLDE (HIE-ISOLDE) project is a major upgrade of the existing ISOLDE and REX-ISOLDE facilities at CERN. The most significant improvement will come from replacing the existing REX accelerating structure by a superconducting linear accelerator (SC linac) composed ultimately of six cryo-modules installed in series, each containing superconducting RF cavities and solenoids operated at 4.5 K. In order to provide the cooling capacity at all temperature levels between 300 K and 4.5 K for the six cryo-modules, an existing helium refrigerator, manufactured in 1986 and previously used to cool the ALEPH magnet during LEP operation from 1989 to 2000, has been refurbished, reinstalled and recommissioned in a dedicated building located next to the HIE-ISOLDE experimental hall. This helium refrigerator has been connected to a new cryogenic distribution line, consisting of a 30-meter long vacuum-insulated transfer line, a 2000-liter storage dewar and six interconnecting valve boxes, one for each cryo-module. This paper describes the whole cryogenic system and presents the commissioning results including the preliminary operation at 4.5 K of the first cryo- module in the experimental hall.

The Feasibility of Linear Motors and High-Energy Thrusters for Massive Aerospace Vehicles

NASA Astrophysics Data System (ADS)

Stull, M. A.

A combination of two propulsion technologies, superconducting linear motors using ambient magnetic fields and high- energy particle beam thrusters, may make it possible to develop massive aerospace vehicles the size of aircraft carriers. If certain critical thresholds can be attained, linear motors can enable massive vehicles to fly within the atmosphere and can propel them to orbit. Thrusters can do neither, because power requirements are prohibitive. However, unless superconductors having extremely high critical current densities can be developed, the interplanetary magnetic field is too weak for linear motors to provide sufficient acceleration to reach even nearby planets. On the other hand, high-energy thrusters can provide adequate acceleration using a minimal amount of reaction mass, at achievable levels of power generation. If the requirements for linear motor propulsion can be met, combining the two modes of propulsion could enable huge nuclear powered spacecraft to reach at least the inner planets of the solar system, the asteroid belt, and possibly Jupiter, in reasonably short times under continuous acceleration, opening them to exploration, resource development and colonization.

SU-F-T-554: Dark Current Effect On CyberKnife Beam Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, H; Chang, A

Purpose: All RF linear accelerators produce dark current to varying degrees when an accelerating voltage and RF input is applied in the absence of electron gun injection. This study is to evaluate how dark current from the linear accelerator of CyberKnife affect the dose in the reference dosimetry. Methods: The G4 CyberKnife system with 6MV photon beam was used in this study. Using the ion chamber and the diode detector, the dose was measured in water with varying time delay between acquiring charges and staring beam-on after applying high-voltage into the linear accelerator. The dose was measured after the timemore » delay with over the range of 0 to 120 seconds in the accelerating high-voltage mode without beam-on, applying 0, 10, 50, 100, and 200 MUs. For the measurements, the collimator of 60 mm was used and the detectors were placed at the depths of 10 cm with the source-to-surface distance of 80 cm. Results: The dark current was constant over time regardless of MU. The dose due to the dark current increased over time linearly with the R-squared value of 0.9983 up to 4.4 cGy for the time 120 seconds. In the dose rate setting of 720 MU/min, the relative dose when applying the accelerating voltage without beam-on was increased over time up to 0.6% but it was less than the leakage radiation resulted from the accelerated head. As the reference dosimetry condition, when 100 MU was delivered after 10 seconds time delay, the relative dose increased by 0.7% but 6.7% for the low MU (10 MU). Conclusion: In the dosimetry using CyberKnife system, the constant dark current affected to the dose. Although the time delay in the accelerating high-voltage mode without beam-on is within 10 seconds, the dose less than 100 cGy can be overestimated more than 1%.« less

Thomas Edison Accelerated Elementary School.

ERIC Educational Resources Information Center

Levin, Henry M.; Chasin, Gene

This paper describes early outcomes of a Sacramento, California, elementary school that participated in the Accelerated Schools Project. The school, which serves many minority and poor students, began training for the project in 1992. Accelerated Schools were designed to advance the learning rate of students through a gifted and talented approach,…

Accelerated testing for studying pavement design and performance (FY 2002) : performance of foamed asphalt stabilized base in full depth reclaimed asphalt pavement.

DOT National Transportation Integrated Search

2004-08-01

This report covers the Fiscal Year 2002 project conducted at the Accelerated Testing Laboratory at Kansas : State University. The project was selected and funded by the Midwest Accelerated Testing Pooled Fund Program , : which includes Iowa, Kansas, ...

Generation and Characterization of Electron Bunches with Ramped Current Profiles in a Dual-Frequency Superconducting Linear Accelerator

DOE PAGES

Piot, P.; Behrens, C.; Gerth, C.; ...

2011-09-07

We report on the successful experimental generation of electron bunches with ramped current profiles. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a superconducing radiofrequency linear accelerator operating at two frequencies and a current-enhancing dispersive section. The produced {approx} 700-MeV bunches have peak currents of the order of a kilo-Ampere. Data taken for various accelerator settings demonstrate the versatility of the method and in particular its ability to produce current profiles that have a quasi-linear dependency on the longitudinal (temporal) coordinate. The measured bunch parameters are shown, via numerical simulations, to produce gigavolt-per-meter peak acceleratingmore » electric fields with transformer ratios larger than 2 in dielectric-lined waveguides.« less

Finite element analyses of a linear-accelerator electron gun

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iqbal, M., E-mail: muniqbal.chep@pu.edu.pk, E-mail: muniqbal@ihep.ac.cn; Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049; Wasy, A.

Thermo-structural analyses of the Beijing Electron-Positron Collider (BEPCII) linear-accelerator, electron gun, were performed for the gun operating with the cathode at 1000 °C. The gun was modeled in computer aided three-dimensional interactive application for finite element analyses through ANSYS workbench. This was followed by simulations using the SLAC electron beam trajectory program EGUN for beam optics analyses. The simulations were compared with experimental results of the assembly to verify its beam parameters under the same boundary conditions. Simulation and test results were found to be in good agreement and hence confirmed the design parameters under the defined operating temperature. The gunmore » is operating continuously since commissioning without any thermal induced failures for the BEPCII linear accelerator.« less

Perception of linear acceleration in weightlessness

NASA Technical Reports Server (NTRS)

Arrott, Anthony P.; Young, Laurence R.; Merfeld, Daniel M.

1991-01-01

Tests of the perception and use of linear acceleration sensory information were performed on the science crews of the Spacelab 1 (SL-1) and D-1 missions using linear 'sleds' in-flight (D-1) and pre-post flight. The time delay between the acceleration step stimulus and the subjective response was consistently reduced during weightlessness, but was neither statistically significant nor of functional importance. Increased variability of responses when going from one environment to the other was apparent from measurements on the first day of the mission and in the first days post-flight. Subjective reports of perceived motion during sinusoidal oscillation in weightlessness were qualitatively similar to reports on earth. In a closed-loop motion nulling task, enhanced performance was observed post-flight in all crewmembers tested in the Y or Z axes.

Perception of linear acceleration in weightlessness

NASA Technical Reports Server (NTRS)

Arrott, A. P.; Young, L. R.; Merfeld, D. M.

1990-01-01

Tests of the perception and use of linear acceleration sensory information were performed on the science crews of the Spacelab 1 (SL-1) and D-1 missions using linear "sleds" in-flight (D-1) and pre-post flight. The time delay between the acceleration step stimulus and the subjective response was consistently reduced during weightlessness, but was neither statistically significant nor of functional importance. Increased variability of responses when going from one environment to the other was apparent from measurements on the first day of the mission and in the first days post-flight. Subjective reports of perceived motion during sinusoidal oscillation in weightlessness were qualitatively similar to reports on earth. In a closed-loop motion nulling task, enhanced performance was observed post-flight in all crewmembers tested in the Y or Z axes.

Assessing the response of the Gulf Coast to global change

NASA Astrophysics Data System (ADS)

Anderson, John B.; Törnqvist, Torbjörn E.; Day, John

2012-11-01

Gulf Coastal Science Consortium Workshop;Houston, Texas, 28-29 June 2012 The newly formed Gulf Coastal Science Consortium held its first workshop at Rice University. The creation of the consortium was prompted by two recent incidents. One incident involved censorship of a book chapter on Galveston Bay by the Texas Commission on Environmental Quality that omitted all references to climate change and accelerated sea-level rise. The other incident was the adoption of legislation in North Carolina that requires planners and developers to assume a linear sea-level rise projection, despite compelling scientific evidence for a multifold increase in sea-level rise in historical time.

Linear induction accelerators made from pulse-line cavities with external pulse injection.

PubMed

Smith, I

1979-06-01

Two types of linear induction accelerator have been reported previously. In one, unidirectional voltage pulses are generated outside the accelerator and injected into the accelerator cavity modules, which contain ferromagnetic material to reduce energy losses in the form of currents induced, in parallel with the beam, in the cavity structure. In the other type, the accelerator cavity modules are themselves pulse-forming lines with energy storage and switches; parallel current losses are made zero by the use of circuits that generate bidirectional acceleration waveforms with a zero voltage-time integral. In a third type of design described here, the cavities are externally driven, and 100% efficient coupling of energy to the beam is obtained by designing the external pulse generators to produce bidirectional voltage waveforms with zero voltage-time integral. A design for such a pulse generator is described that is itself one hundred percent efficient and which is well suited to existing pulse power techniques. Two accelerator cavity designs are described that can couple the pulse from such a generator to the beam; one of these designs provides voltage doubling. Comparison is made between the accelerating gradients that can be obtained with this and the preceding types of induction accelerator.

Aligning the magnetic field of a linear induction accelerator with a low-energy electron beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, J.C.; Deadrick, F.J.; Kallman, J.S.

1989-03-10

The Experimental Test Accelerator II (ETA-II) linear induction accelerator at Lawrence Livermore National Laboratory uses a solenoid magnet in each acceleration cell to focus and transport an electron beam over the length of the accelerator. To control growth of the corkscrew mode the magnetic field must be precisely aligned over the full length of the accelerate. Concentric with each solenoid magnet is sine/cosmic-wound correction coil to steer the beam and correct field errors. A low-energy electron probe traces the central flux line through the accelerator referenced to a mechanical axis that is defined by a copropagating laser beam. Correction coilsmore » are activated to force the central flux line to cross the mechanical axis at the end of each acceleration cell. The ratios of correction coil currents determined by the low-energy electron probe are then kept fixed to correct for field errors during normal operation with an accelerated beam. We describe the construction of the low-energy electron probe and report the results of experiments we conducted to measure magnetic alignment with and without the correction coils activated. 5 refs., 3 figs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clendenin, James E

The International Committee supported the proposal of the Chairman of the XVIII International Linac Conference to issue a new Compendium of linear accelerators. The last one was published in 1976. The Local Organizing Committee of Linac96 decided to set up a sub-committee for this purpose. Contrary to the catalogues of the High Energy Accelerators which compile accelerators with energies above 1 GeV, we have not defined a specific limit in energy. Microtrons and cyclotrons are not in this compendium. Also data from thousands of medical and industrial linacs has not been collected. Therefore, only scientific linacs are listed in themore » present compendium. Each linac found in this research and involved in a physics context was considered. It could be used, for example, either as an injector for high energy accelerators, or in nuclear physics, materials physics, free electron lasers or synchrotron light machines. Linear accelerators are developed in three continents only: America, Asia, and Europe. This geographical distribution is kept as a basis. The compendium contains the parameters and status of scientific linacs. Most of these linacs are operational. However, many facilities under construction or design studies are also included. A special mention has been made at the end for the studies of future linear colliders.« less

Radio to Gamma-Ray Emission from Shell-Type Supernova Remnants: Predictions from Non-Linear Shock Acceleration Models

NASA Technical Reports Server (NTRS)

Baring, Matthew G.; Ellison, Donald C.; Reynolds, Stephen P.; Grenier, Isabelle A.; Goret, Philippe

1998-01-01

Supernova remnants (SNRs) are widely believed to be the principal source of galactic cosmic rays, produced by diffusive shock acceleration in the environs of the remnant's expanding blast wave. Such energetic particles can produce gamma-rays and lower energy photons via interactions with the ambient plasma. The recently reported observation of TeV gamma-rays from SN1006 by the CANGAROO Collaboration, combined with the fact that several unidentified EGRET sources have been associated with known radio/optical/X-ray-emitting remnants, provides powerful motivation for studying gamma-ray emission from SNRs. In this paper, we present results from a Monte Carlo simulation of non-linear shock structure and acceleration coupled with photon emission in shell-like SNRs. These non-linearities are a by-product of the dynamical influence of the accelerated cosmic rays on the shocked plasma and result in distributions of cosmic rays which deviate from pure power-laws. Such deviations are crucial to acceleration efficiency considerations and impact photon intensities and spectral shapes at all energies, producing GeV/TeV intensity ratios that are quite different from test particle predictions.

Quasi-linear heating and acceleration in bi-Maxwellian plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hellinger, Petr; Passot, Thierry; Sulem, Pierre-Louis

2013-12-15

Quasi-linear acceleration and heating rates are derived for drifting bi-Maxwellian distribution functions in a general nonrelativistic case for arbitrary wave vectors, propagation angles, and growth/damping rates. The heating rates in a proton-electron plasma due to ion-cyclotron/kinetic Alfvén and mirror waves for a wide range of wavelengths, directions of propagation, and growth or damping rates are explicitly computed.

A linear accelerator for simulated micrometeors.

NASA Technical Reports Server (NTRS)

Slattery, J. C.; Becker, D. G.; Hamermesh, B.; Roy, N. L.

1973-01-01

Review of the theory, design parameters, and construction details of a linear accelerator designed to impart meteoric velocities to charged microparticles in the 1- to 10-micron diameter range. The described linac is of the Sloan Lawrence type and, in a significant departure from conventional accelerator practice, is adapted to single particle operation by employing a square wave driving voltage with the frequency automatically adjusted from 12.5 to 125 kHz according to the variable velocity of each injected particle. Any output velocity up to about 30 km/sec can easily be selected, with a repetition rate of approximately two particles per minute.

Experimental demonstration of high efficiency electron cyclotron autoresonance acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaPointe, M.A.; Yoder, R.B.; Wang, C.

1996-04-01

First experimental results are reported on the operation of a multimegawatt 2.856 GHz cyclotron autoresonance accelerator (CARA). A 90{endash}100 kV, 2{endash}3 MW linear electron beam has had up to6.6 MW added to it in CARA, with an rf-to-beam power efficiency of up to 96{percent}. This efficiency level is larger than that reported for any fast-wave interaction between radiation and electrons, and also larger than that in normal conducting rf linear accelerators. The results obtained are in good agreement with theoretical predictions. {copyright} {ital 1996 The American Physical Society.}

Project delivery acceleration tool box : improvements to the Department of Transportation's project delivery process.

DOT National Transportation Integrated Search

2004-05-01

The purpose of this document is to provide to Caltrans' employees, as well as external partners, some valuable tools that can be used to help accelerate project delivery. This document contains a compilation of all the Department's recent acceleratio...

Development of the integrated control system for the microwave ion source of the PEFP 100-MeV proton accelerator

NASA Astrophysics Data System (ADS)

Song, Young-Gi; Seol, Kyung-Tae; Jang, Ji-Ho; Kwon, Hyeok-Jung; Cho, Yong-Sub

2012-07-01

The Proton Engineering Frontier Project (PEFP) 20-MeV proton linear accelerator is currently operating at the Korea Atomic Energy Research Institute (KAERI). The ion source of the 100-MeV proton linac needs at least a 100-hour operation time. To meet the goal, we have developed a microwave ion source that uses no filament. For the ion source, a remote control system has been developed by using experimental physics and the industrial control system (EPICS) software framework. The control system consists of a versa module europa (VME) and EPICS-based embedded applications running on a VxWorks real-time operating system. The main purpose of the control system is to control and monitor the operational variables of the components remotely and to protect operators from radiation exposure and the components from critical problems during beam extraction. We successfully performed the operation test of the control system to confirm the degree of safety during the hardware performance.

Monte Carlo Simulation of a 12 MeV Cargo Container Inspection System

NASA Astrophysics Data System (ADS)

Ozcan, Ibrahim; Chandler, Katherine; Spaulding, Randy; Farfan, Eduardo

2007-05-01

After the terrorist events of 9/11, border security has become one of the most important issues in national security due to the large number of cargo containers entering the country. Screening of all cargo containers for nuclear materials should be performed during border inspections. The technical aspects of inspecting cargo containers using electron accelerators have been studied previously. However, the radiological protection aspects involved in these studies have not been fully considered. This screening process may accidentally harm operators, workers, and bystanders; as well as stowaways hiding inside the containers. In this research project, external doses were estimated at various locations near the inspection system. A 12-MeV linear accelerator (LINAC) was used in the experiment. The relationship between the various locations and doses were determined in this simulation. The simulation was performed using MCNPX. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NWS07.B2.8

Optical surface properties and their RF limitations of European XFEL cavities

NASA Astrophysics Data System (ADS)

Wenskat, Marc

2017-10-01

The inner surface of superconducting cavities plays a crucial role to achieve highest accelerating fields and low losses. The industrial fabrication of cavities for the European X-ray Free Electron Laser and the International Linear Collider HiGrade Research Project allowed for an investigation of this interplay. For the serial inspection of the inner surface, the optical inspection robot ’optical bench for automated cavity inspection with high resolution on short timescales’ OBACHT was constructed and to analyze the large amount of data, represented in the images of the inner surface, an image processing and analysis code was developed and new variables to describe the cavity surface were obtained. This quantitative analysis identified vendor-specific surface properties which allow the performance of quality control and assurance during production. In addition, a strong negative correlation of ρ =-0.93 with a significance of 6 σ of the integrated grain boundary area \\sum {A} versus the maximal achievable accelerating field {{E}}{acc,\\max } has been found.

Accelerating separable footprint (SF) forward and back projection on GPU

NASA Astrophysics Data System (ADS)

Xie, Xiaobin; McGaffin, Madison G.; Long, Yong; Fessler, Jeffrey A.; Wen, Minhua; Lin, James

2017-03-01

Statistical image reconstruction (SIR) methods for X-ray CT can improve image quality and reduce radiation dosages over conventional reconstruction methods, such as filtered back projection (FBP). However, SIR methods require much longer computation time. The separable footprint (SF) forward and back projection technique simplifies the calculation of intersecting volumes of image voxels and finite-size beams in a way that is both accurate and efficient for parallel implementation. We propose a new method to accelerate the SF forward and back projection on GPU with NVIDIA's CUDA environment. For the forward projection, we parallelize over all detector cells. For the back projection, we parallelize over all 3D image voxels. The simulation results show that the proposed method is faster than the acceleration method of the SF projectors proposed by Wu and Fessler.13 We further accelerate the proposed method using multiple GPUs. The results show that the computation time is reduced approximately proportional to the number of GPUs.

Accelerated Districts--The Next Step. A Summary of Research and Design.

ERIC Educational Resources Information Center

Driver, Cyrus; And Others

The National Center for the Accelerated Schools Project at Stanford University has recognized that district-level change is necessary if changes at accelerated schools are to gain permanence and become widespread. The Center has therefore initiated a research and development project to design a set of models on which districts can reconstitute…

Accelerating the Learning of At-Risk Students: An Evaluation of Project ACCEL.

ERIC Educational Resources Information Center

Ramaswami, Soundaram

Project Accelerated Curriculum Classes Emphasizing Learning (ACCEL) was implemented by the Newark School District (New Jersey) in the 1989-90 school year in response to the ineffective practice of retaining underachieving students. The innovative approach of accelerated learning was made available to retained sixth and seventh grade students.…

TAC Proton Accelerator Facility: The Status and Road Map

DOE Office of Scientific and Technical Information (OSTI.GOV)

Algin, E.; Akkus, B.; Caliskan, A.

2011-06-28

Proton Accelerator (PA) Project is at a stage of development, working towards a Technical Design Report under the roof of a larger-scale Turkish Accelerator Center (TAC) Project. The project is supported by the Turkish State Planning Organization. The PA facility will be constructed in a series of stages including a 3 MeV test stand, a 55 MeV linac which can be extended to 100+ MeV, and then a full 1-3 GeV proton synchrotron or superconducting linac. In this article, science applications, overview, and current status of the PA Project will be given.

Accelerator-based BNCT.

PubMed

Kreiner, A J; Baldo, M; Bergueiro, J R; Cartelli, D; Castell, W; Thatar Vento, V; Gomez Asoia, J; Mercuri, D; Padulo, J; Suarez Sandin, J C; Erhardt, J; Kesque, J M; Valda, A A; Debray, M E; Somacal, H R; Igarzabal, M; Minsky, D M; Herrera, M S; Capoulat, M E; Gonzalez, S J; del Grosso, M F; Gagetti, L; Suarez Anzorena, M; Gun, M; Carranza, O

2014-06-01

The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. In particular, the present status and recent progress of the Argentine project will be reviewed. The topics will cover: intense ion sources, accelerator tubes, transport of intense beams, beam diagnostics, the (9)Be(d,n) reaction as a possible neutron source, Beam Shaping Assemblies (BSA), a treatment room, and treatment planning in realistic cases. © 2013 Elsevier Ltd. All rights reserved.

Head impact exposure sustained by football players on days of diagnosed concussion.

PubMed

Beckwith, Jonathan G; Greenwald, Richard M; Chu, Jeffrey J; Crisco, Joseph J; Rowson, Steven; Duma, Stefan M; Broglio, Steven P; McAllister, Thomas W; Guskiewicz, Kevin M; Mihalik, Jason P; Anderson, Scott; Schnebel, Brock; Brolinson, P Gunnar; Collins, Michael W

2013-04-01

This study compares the frequency and severity of head impacts sustained by football players on days with and without diagnosed concussion and to identify the sensitivity and specificity of single-impact severity measures to diagnosed injury. One thousand two hundred eight players from eight collegiate football teams and six high school football teams wore instrumented helmets to measure head impacts during all team sessions, of which 95 players were diagnosed with concussion. Eight players sustained two injuries and one sustained three, providing 105 injury cases. Measures of head kinematics (peak linear and rotational acceleration, Gadd severity index, head injury criteria (HIC15), and change in head velocity (Δv)) and the number of head impacts sustained by individual players were compared between days with and without diagnosed concussion. Receiver operating characteristic curves were generated to evaluate the sensitivity and specificity of each kinematic measure to diagnosed concussion using only those impacts that directly preceded diagnosis. Players sustained a higher frequency of impacts and impacts with more severe kinematic properties on days of diagnosed concussion than on days without diagnosed concussion. Forty-five injury cases were immediately diagnosed after head impact. For these cases, peak linear acceleration and HIC15 were most sensitive to immediately diagnosed concussion (area under the curve = 0.983). Peak rotational acceleration was less sensitive to diagnosed injury than all other kinematic measures (P = 0.01), which are derived from linear acceleration (peak linear, HIC15, Gadd severity index, and Δv). Players sustained more impacts and impacts of higher severity on days of diagnosed concussion than on days without diagnosed concussion. In addition, of historical measures of impact severity, those associated with peak linear acceleration are the best predictors of immediately diagnosed concussion.

Head Impact Exposure Sustained by Football Players on Days of Diagnosed Concussion

PubMed Central

Beckwith, Jonathan G.; Greenwald, Richard M.; Chu, Jeffrey J.; Crisco, Joseph J.; Rowson, Steven; Duma, Stefan M.; Broglio, Steven P.; McAllister, Thomas W.; Guskiewicz, Kevin M.; Mihalik, Jason P.; Anderson, Scott; Schnebel, Brock; Brolinson, P. Gunnar; Collins, Michael W.

2012-01-01

Purpose This study compares the frequency and severity of head impacts sustained by football players on days with and without diagnosed concussion and to identify the sensitivity and specificity of single impact severity measures to diagnosed injury. Methods 1,208 players from eight collegiate and six high school football teams wore instrumented helmets to measure head impacts during all team sessions, of which 95 players were diagnosed with concussion. Eight players sustained two injuries and one three, providing 105 injury cases. Measures of head kinematics (peak linear and rotational acceleration, Gadd Severity Index (GSI), Head Injury Criteria (HIC15), change in head velocity (Δv)) and the number of head impacts sustained by individual players were compared between days with and without diagnosed concussion. Receiver operator characteristic curves were generated to evaluate the sensitivity and specificity of each kinematic measure to diagnosed concussion using only those impacts that directly preceded diagnosis. Results Players sustained a higher frequency of impacts and impacts with more severe kinematic properties on days of diagnosed concussion than on days without diagnosed concussion. Forty-five injury cases were immediately diagnosed following head impact. For these cases, peak linear acceleration and HIC15 were most sensitive to immediately diagnosed concussion (AUC = 0.983). Peak rotational acceleration was less sensitive to diagnosed injury than all other kinematic measures (p = 0.01) which are derived from linear acceleration (peak linear, HIC15, GSI, and Δv). Conclusions Players sustain more impacts and impacts of higher severity on days of diagnosed concussion than on days without diagnosed concussion. Additionally, of historical measures of impact severity, those associated with peak linear acceleration are the best predictors of immediately diagnosed concussion. PMID:23135363

Analysis of peripheral doses for base of tongue treatment by linear accelerator and helical TomoTherapy IMRT

PubMed Central

Lamba, Michael A. S.; Elson, Howard R.

2010-01-01

The purpose of this study was to compare the peripheral doses to various organs from a typical head and neck intensity‐modulated radiation therapy (IMRT) treatment delivered by linear accelerator (linac) and helical TomoTherapy. Multiple human CT data sets were used to segment critical structures and organs at risk, fused and adjusted to an anthropomorphic phantom. Eighteen contours were designated for thermoluminescent dosimeter (TLD) placement. Following the RTOG IMRT Protocol 0522, treatment of the primary tumor and involved nodes (PTV70) and subclinical disease sites (PTV56) was planned utilizing IMRT to 70 Gy and 56 Gy. Clinically acceptable treatment plans were produced for linac and TomoTherapy treatments. TLDs were placed and each treatment plan was delivered to the anthropomorphic phantom four times. Within 2.5 cm (one helical TomoTherapy field width) superior and inferior to the field edges, normal tissue doses were on average 45% lower using linear accelerator. Beyond 2.5 cm, the helical TomoTherapy normal tissue dose was an average of 52% lower. The majority of points proved to be statistically different using the Student's t‐test with p<0.05. Using one method of calculation, probability of a secondary malignancy was 5.88% for the linear accelerator and 4.08% for helical TomoTherapy. Helical TomoTherapy delivers more dose than a linac immediately above and below the treatment field, contributing to the higher peripheral doses adjacent to the field. At distances beyond one field width (where leakage is dominant), helical TomoTherapy doses are lower than linear accelerator doses. PACS number: 87.50.cm Dosimetry/exposure assessment

Correction of scatter in megavoltage cone-beam CT

NASA Astrophysics Data System (ADS)

Spies, L.; Ebert, M.; Groh, B. A.; Hesse, B. M.; Bortfeld, T.

2001-03-01

The role of scatter in a cone-beam computed tomography system using the therapeutic beam of a medical linear accelerator and a commercial electronic portal imaging device (EPID) is investigated. A scatter correction method is presented which is based on a superposition of Monte Carlo generated scatter kernels. The kernels are adapted to both the spectral response of the EPID and the dimensions of the phantom being scanned. The method is part of a calibration procedure which converts the measured transmission data acquired for each projection angle into water-equivalent thicknesses. Tomographic reconstruction of the projections then yields an estimate of the electron density distribution of the phantom. It is found that scatter produces cupping artefacts in the reconstructed tomograms. Furthermore, reconstructed electron densities deviate greatly (by about 30%) from their expected values. The scatter correction method removes the cupping artefacts and decreases the deviations from 30% down to about 8%.

Limits on the adaptability of coastal marshes to rising sea level

USGS Publications Warehouse

Kirwan, Matthew L.; Guntenspergen, Glenn R.; D'Alpaos, Andrea; Morris, James T.; Mudd, Simon M.; Temmerman, Stijn

2010-01-01

Assumptions of a static landscape inspire predictions that about half of the world's coastal wetlands will submerge during this century in response to sea-level acceleration. In contrast, we use simulations from five numerical models to quantify the conditions under which ecogeomorphic feedbacks allow coastal wetlands to adapt to projected changes in sea level. In contrast to previous sea-level assessments, we find that non-linear feedbacks among inundation, plant growth, organic matter accretion, and sediment deposition, allow marshes to survive conservative projections of sea-level rise where suspended sediment concentrations are greater than ~20 mg/L. Under scenarios of more rapid sea-level rise (e.g., those that include ice sheet melting), marshes will likely submerge near the end of the 21st century. Our results emphasize that in areas of rapid geomorphic change, predicting the response of ecosystems to climate change requires consideration of the ability of biological processes to modify their physical environment.

An extended macro model accounting for acceleration changes with memory and numerical tests

NASA Astrophysics Data System (ADS)

Cheng, Rongjun; Ge, Hongxia; Sun, Fengxin; Wang, Jufeng

2018-09-01

Considering effect of acceleration changes with memory, an improved continuum model of traffic flow is proposed in this paper. By applying the linear stability theory, we derived the new model's linear stability condition. Through nonlinear analysis, the KdV-Burgers equation is derived to describe the propagating behavior of traffic density wave near the neutral stability line. Numerical simulation is carried out to study the extended traffic flow model, which explores how acceleration changes with memory affected each car's velocity, density and fuel consumption and exhaust emissions. Numerical results demonstrate that acceleration changes with memory have significant negative effect on dynamic characteristic of traffic flow. Furthermore, research results verify that the effect of acceleration changes with memory will deteriorate the stability of traffic flow and increase cars' total fuel consumptions and emissions during the whole evolution of small perturbation.

Separated-orbit bisected energy-recovered linear accelerator

DOEpatents

Douglas, David R.

2015-09-01

A separated-orbit bisected energy-recovered linear accelerator apparatus and method. The accelerator includes a first linac, a second linac, and a plurality of arcs of differing path lengths, including a plurality of up arcs, a plurality of downgoing arcs, and a full energy arc providing a path independent of the up arcs and downgoing arcs. The up arcs have a path length that is substantially a multiple of the RF wavelength and the full energy arc includes a path length that is substantially an odd half-integer multiple of the RF wavelength. Operation of the accelerator includes accelerating the beam utilizing the linacs and up arcs until the beam is at full energy, at full energy executing a full recirculation to the second linac using a path length that is substantially an odd half-integer of the RF wavelength, and then decelerating the beam using the linacs and downgoing arcs.

Enhanced dielectric-wall linear accelerator

DOEpatents

Sampayan, S.E.; Caporaso, G.J.; Kirbie, H.C.

1998-09-22

A dielectric-wall linear accelerator is enhanced by a high-voltage, fast e-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface. 6 figs.

Enhanced dielectric-wall linear accelerator

DOEpatents

Sampayan, Stephen E.; Caporaso, George J.; Kirbie, Hugh C.

1998-01-01

A dielectric-wall linear accelerator is enhanced by a high-voltage, fast e-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

New concept on an integrated interior magnetic resonance imaging and medical linear accelerator system for radiation therapy.

PubMed

Jia, Xun; Tian, Zhen; Xi, Yan; Jiang, Steve B; Wang, Ge

2017-01-01

Image guidance plays a critical role in radiotherapy. Currently, cone-beam computed tomography (CBCT) is routinely used in clinics for this purpose. While this modality can provide an attenuation image for therapeutic planning, low soft-tissue contrast affects the delineation of anatomical and pathological features. Efforts have recently been devoted to several MRI linear accelerator (LINAC) projects that lead to the successful combination of a full diagnostic MRI scanner with a radiotherapy machine. We present a new concept for the development of the MRI-LINAC system. Instead of combining a full MRI scanner with the LINAC platform, we propose using an interior MRI (iMRI) approach to image a specific region of interest (RoI) containing the radiation treatment target. While the conventional CBCT component still delivers a global image of the patient's anatomy, the iMRI offers local imaging of high soft-tissue contrast for tumor delineation. We describe a top-level system design for the integration of an iMRI component into an existing LINAC platform. We performed numerical analyses of the magnetic field for the iMRI to show potentially acceptable field properties in a spherical RoI with a diameter of 15 cm. This field could be shielded to a sufficiently low level around the LINAC region to avoid electromagnetic interference. Furthermore, we investigate the dosimetric impacts of this integration on the radiotherapy beam.

Thermal Analysis of the ILC Superconductin Quadrupole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, Ian; /Rose-Hulman Inst., Terre Haute /SLAC

2006-09-13

Critical to a particle accelerator's functioning, superconducting magnets serve to focus and aim the particle beam. The Stanford Linear Accelerator Center (SLAC) has received a prototype superconducting quadrupole designed and built by the Centro de Investigaciones Energ{acute e}ticas, Medioambientales y Tecnol{acute o}gicas (CIEMAT) to be evaluated for the International Linear Collider (ILC) project. To ensure proper functioning of the magnet, the device must be maintained at cryogenic temperatures by use of a cooling system containing liquid nitrogen and liquid helium. The cool down period of a low temperature cryostat is critical to the success of an experiment, especially a prototypemore » setup such as this one. The magnet and the dewar each contain unique heat leaks and material properties. These differences can lead to tremendous thermal stresses. The system was analyzed mathematically, leading to ideal liquid helium and liquid nitrogen flow rates during the magnet's cool-down to 4.2 K, along with a reasonable estimate of how long this cool-down will take. With a flow rate of ten gaseous liters of liquid nitrogen per minute, the nitrogen shield will take approximately five hours to cool down to 77 K. With a gaseous helium flow rate of sixty liters per minute, the magnet will take at least nineteen hours to cool down to a temperature of 4.2 K.« less

Response of an Impact Test Apparatus for Fall Protective Headgear Testing Using a Hybrid-III Head/Neck Assembly

PubMed Central

Caccese, V.; Ferguson, J.; Lloyd, J.; Edgecomb, M.; Seidi, M.; Hajiaghamemar, M.

2017-01-01

A test method based upon a Hybrid-III head and neck assembly that includes measurement of both linear and angular acceleration is investigated for potential use in impact testing of protective headgear. The test apparatus is based upon a twin wire drop test system modified with the head/neck assembly and associated flyarm components. This study represents a preliminary assessment of the test apparatus for use in the development of protective headgear designed to prevent injury due to falls. By including angular acceleration in the test protocol it becomes possible to assess and intentionally reduce this component of acceleration. Comparisons of standard and reduced durometer necks, various anvils, front, rear, and side drop orientations, and response data on performance of the apparatus are provided. Injury measures summarized for an unprotected drop include maximum linear and angular acceleration, head injury criteria (HIC), rotational injury criteria (RIC), and power rotational head injury criteria (PRHIC). Coefficient of variation for multiple drops ranged from 0.4 to 6.7% for linear acceleration. Angular acceleration recorded in a side drop orientation resulted in highest coefficient of variation of 16.3%. The drop test apparatus results in a reasonably repeatable test method that has potential to be used in studies of headgear designed to reduce head impact injury. PMID:28216804

A Conforming Multigrid Method for the Pure Traction Problem of Linear Elasticity: Mixed Formulation

NASA Technical Reports Server (NTRS)

Lee, Chang-Ock

1996-01-01

A multigrid method using conforming P-1 finite element is developed for the two-dimensional pure traction boundary value problem of linear elasticity. The convergence is uniform even as the material becomes nearly incompressible. A heuristic argument for acceleration of the multigrid method is discussed as well. Numerical results with and without this acceleration as well as performance estimates on a parallel computer are included.

Visual-vestibular interaction

NASA Technical Reports Server (NTRS)

Young, Laurence R.; Merfeld, D.

1994-01-01

Significant progress was achieved during the period of this grant on a number of different fronts. A list of publications, abstracts, and theses supported by this grant is provided at the end of this document. The completed studies focused on three general areas: eye movements induced by dynamic linear acceleration, eye movements and vection reports induced by visual roll stimulation, and the separation of gravito-inertial force into central estimates of gravity and linear acceleration.

Linear induction accelerator

DOEpatents

Buttram, M.T.; Ginn, J.W.

1988-06-21

A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities. 4 figs.

Laser-Induced Linear-Field Particle Acceleration in Free Space.

PubMed

Wong, Liang Jie; Hong, Kyung-Han; Carbajo, Sergio; Fallahi, Arya; Piot, Philippe; Soljačić, Marin; Joannopoulos, John D; Kärtner, Franz X; Kaminer, Ido

2017-09-11

Linear-field particle acceleration in free space (which is distinct from geometries like the linac that requires components in the vicinity of the particle) has been studied for over 20 years, and its ability to eventually produce high-quality, high energy multi-particle bunches has remained a subject of great interest. Arguments can certainly be made that linear-field particle acceleration in free space is very doubtful given that first-order electron-photon interactions are forbidden in free space. Nevertheless, we chose to develop an accurate and truly predictive theoretical formalism to explore this remote possibility when intense, few-cycle electromagnetic pulses are used in a computational experiment. The formalism includes exact treatment of Maxwell's equations and exact treatment of the interaction among the multiple individual particles at near and far field. Several surprising results emerge. We find that electrons interacting with intense laser pulses in free space are capable of gaining substantial amounts of energy that scale linearly with the field amplitude. For example, 30 keV electrons (2.5% energy spread) are accelerated to 61 MeV (0.5% spread) and to 205 MeV (0.25% spread) using 250 mJ and 2.5 J lasers respectively. These findings carry important implications for our understanding of ultrafast electron-photon interactions in strong fields.

Klystron-linac combination

DOEpatents

Stein, W.E.

1980-04-24

A combination klystron-linear accelerator which utilizes anti-bunch electrons generated in the klystron section as a source of electrons to be accelerated in the accelerator section. Electron beam current is controlled by second harmonic bunching, constrictor aperture size and magnetic focusing. Rf coupling is achieved by internal and external coupling.

Adaptation to vestibular disorientation. XI, The influence of specific and nonspecific gravi-receptors on nystagmic responses to angular acceleration.

DOT National Transportation Integrated Search

1969-10-01

Data from several recent experiments indicate that the otoliths (detectors of linear acceleration) may exert regulatory effects on responses of the semicircular canals (detectors of angular acceleration). This study was designed to explore further th...

openSE: a Systems Engineering Framework Particularly Suited to Particle Accelerator Studies and Development Projects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonnal, P.; Féral, B.; Kershaw, K.

Particle accelerator projects share many characteristics with industrial projects. However, experience has shown that best practice of industrial project management is not always well suited to particle accelerator projects. Major differences include the number and complexity of technologies involved, the importance of collaborative work, development phases that can last more than a decade, and the importance of telerobotics and remote handling to address future preventive and corrective maintenance requirements due to induced radioactivity, to cite just a few. The openSE framework it is a systems engineering and project management framework specifically designed for scientific facilities’ systems and equipment studies andmore » development projects. Best practices in project management, in systems and requirements engineering, in telerobotics and remote handling and in radiation safety management were used as sources of inspiration, together with analysis of current practices surveyed at CERN, GSI and ESS.« less

Particle acceleration in regions of magnetic flux emergence: a statistical approach using test-particle- and MHD-simulations

NASA Astrophysics Data System (ADS)

Vlahos, Loukas; Archontis, Vasilis; Isliker, Heinz

We consider 3D nonlinear MHD simulations of an emerging flux tube, from the convection zone into the corona, focusing on the coronal part of the simulations. We first analyze the statistical nature and spatial structure of the electric field, calculating histograms and making use of iso-contour visualizations. Then test-particle simulations are performed for electrons, in order to study heating and acceleration phenomena, as well as to determine HXR emission. This study is done by comparatively exploring quiet, turbulent explosive, and mildly explosive phases of the MHD simulations. Also, the importance of collisional and relativistic effects is assessed, and the role of the integration time is investigated. Particular aim of this project is to verify the quasi- linear assumptions made in standard transport models, and to identify possible transport effects that cannot be captured with the latter. In order to determine the relation of our results to Fermi acceleration and Fokker-Planck modeling, we determine the standard transport coefficients. After all, we find that the electric field of the MHD simulations must be downscaled in order to prevent an un-physically high degree of acceleration, and the value chosen for the scale factor strongly affects the results. In different MHD time-instances we find heating to take place, and acceleration that depends on the level of MHD turbulence. Also, acceleration appears to be a transient phenomenon, there is a kind of saturation effect, and the parallel dynamics clearly dominate the energetics. The HXR spectra are not yet really compatible with observations, we have though to further explore the scaling of the electric field and the integration times used.

Perception of the dynamic visual vertical during sinusoidal linear motion.

PubMed

Pomante, A; Selen, L P J; Medendorp, W P

2017-10-01

The vestibular system provides information for spatial orientation. However, this information is ambiguous: because the otoliths sense the gravitoinertial force, they cannot distinguish gravitational and inertial components. As a consequence, prolonged linear acceleration of the head can be interpreted as tilt, referred to as the somatogravic effect. Previous modeling work suggests that the brain disambiguates the otolith signal according to the rules of Bayesian inference, combining noisy canal cues with the a priori assumption that prolonged linear accelerations are unlikely. Within this modeling framework the noise of the vestibular signals affects the dynamic characteristics of the tilt percept during linear whole-body motion. To test this prediction, we devised a novel paradigm to psychometrically characterize the dynamic visual vertical-as a proxy for the tilt percept-during passive sinusoidal linear motion along the interaural axis (0.33 Hz motion frequency, 1.75 m/s 2 peak acceleration, 80 cm displacement). While subjects ( n =10) kept fixation on a central body-fixed light, a line was briefly flashed (5 ms) at different phases of the motion, the orientation of which had to be judged relative to gravity. Consistent with the model's prediction, subjects showed a phase-dependent modulation of the dynamic visual vertical, with a subject-specific phase shift with respect to the imposed acceleration signal. The magnitude of this modulation was smaller than predicted, suggesting a contribution of nonvestibular signals to the dynamic visual vertical. Despite their dampening effect, our findings may point to a link between the noise components in the vestibular system and the characteristics of dynamic visual vertical. NEW & NOTEWORTHY A fundamental question in neuroscience is how the brain processes vestibular signals to infer the orientation of the body and objects in space. We show that, under sinusoidal linear motion, systematic error patterns appear in the disambiguation of linear acceleration and spatial orientation. We discuss the dynamics of these illusory percepts in terms of a dynamic Bayesian model that combines uncertainty in the vestibular signals with priors based on the natural statistics of head motion. Copyright © 2017 the American Physiological Society.

Generation and characterization of electron bunches with ramped current profiles in a dual-frequency superconducting linear accelerator.

PubMed

Piot, P; Behrens, C; Gerth, C; Dohlus, M; Lemery, F; Mihalcea, D; Stoltz, P; Vogt, M

2012-01-20

We report on the successful experimental generation of electron bunches with ramped current profiles. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a superconducing radio frequency linear accelerator operating at two frequencies and a current-enhancing dispersive section. The produced ~700-MeV bunches have peak currents of the order of a kilo-Ampère. Data taken for various accelerator settings demonstrate the versatility of the method and, in particular, its ability to produce current profiles that have a quasilinear dependency on the longitudinal (temporal) coordinate. The measured bunch parameters are shown, via numerical simulations, to produce gigavolt-per-meter peak accelerating electric fields with transformer ratios larger than 2 in dielectric-lined waveguides. © 2012 American Physical Society

Choosing order of operations to accelerate strip structure analysis in parameter range

NASA Astrophysics Data System (ADS)

Kuksenko, S. P.; Akhunov, R. R.; Gazizov, T. R.

2018-05-01

The paper considers the issue of using iteration methods in solving the sequence of linear algebraic systems obtained in quasistatic analysis of strip structures with the method of moments. Using the analysis of 4 strip structures, the authors have proved that additional acceleration (up to 2.21 times) of the iterative process can be obtained during the process of solving linear systems repeatedly by means of choosing a proper order of operations and a preconditioner. The obtained results can be used to accelerate the process of computer-aided design of various strip structures. The choice of the order of operations to accelerate the process is quite simple, universal and could be used not only for strip structure analysis but also for a wide range of computational problems.

Modelling and Closed-Loop System Identification of a Quadrotor-Based Aerial Manipulator

NASA Astrophysics Data System (ADS)

Dube, Chioniso; Pedro, Jimoh O.

2018-05-01

This paper presents the modelling and system identification of a quadrotor-based aerial manipulator. The aerial manipulator model is first derived analytically using the Newton-Euler formulation for the quadrotor and Recursive Newton-Euler formulation for the manipulator. The aerial manipulator is then simulated with the quadrotor under Proportional Derivative (PD) control, with the manipulator in motion. The simulation data is then used for system identification of the aerial manipulator. Auto Regressive with eXogenous inputs (ARX) models are obtained from the system identification for linear accelerations \\ddot{X} and \\ddot{Y} and yaw angular acceleration \\ddot{\\psi }. For linear acceleration \\ddot{Z}, and pitch and roll angular accelerations \\ddot{θ } and \\ddot{φ }, Auto Regressive Moving Average with eXogenous inputs (ARMAX) models are identified.

Linear fixed-field multipass arcs for recirculating linear accelerators

DOE PAGES

Morozov, V. S.; Bogacz, S. A.; Roblin, Y. R.; ...

2012-06-14

Recirculating Linear Accelerators (RLA's) provide a compact and efficient way of accelerating particle beams to medium and high energies by reusing the same linac for multiple passes. In the conventional scheme, after each pass, the different energy beams coming out of the linac are separated and directed into appropriate arcs for recirculation, with each pass requiring a separate fixed-energy arc. In this paper we present a concept of an RLA return arc based on linear combined-function magnets, in which two and potentially more consecutive passes with very different energies are transported through the same string of magnets. By adjusting themore » dipole and quadrupole components of the constituting linear combined-function magnets, the arc is designed to be achromatic and to have zero initial and final reference orbit offsets for all transported beam energies. We demonstrate the concept by developing a design for a droplet-shaped return arc for a dog-bone RLA capable of transporting two beam passes with momenta different by a factor of two. Finally, we present the results of tracking simulations of the two passes and lay out the path to end-to-end design and simulation of a complete dog-bone RLA.« less

Antigraviceptive neck muscle responses to "moving up and moving down" in human.

PubMed

Aoki, M; Han, X Y; Yamada, H; Muto, T; Satake, H; Ito, Y; Matsunami, K

2000-07-01

The responses of neck muscle to sudden transit from one 'g' to hyper 'g', work to support the head and remain the relative position of head on trunk as common observed: i.e. in sudden acceleration or deceleration by car or ejection of pilot from aircraft. Accordingly it is highly possible that the neck muscle responses to moving up may be important to prevent the neck injury due to sudden linear acceleration such as moving up against gravity. However little is known about the evaluation of mechanism of this reflex. Therefore the present study was conducted with two aims. The first aim was to investigate the neck muscle responses to vertical linear acceleration bv 0.4 g produced with an electro-hydraulic servo-system. We chose the vertical linear acceleration because it activates mainly sacculus, from which afferents have been demonstrated to be connected directly to sternocleidomastoid muscle in animals and human. The second aim was to determine whether there is a difference of neck muscle response to moving down and moving up.

Antigraviceptive neck muscle responses to "moving up and moving down" in human

NASA Technical Reports Server (NTRS)

Aoki, M.; Han, X. Y.; Yamada, H.; Muto, T.; Satake, H.; Ito, Y.; Matsunami, K.

2000-01-01

The responses of neck muscle to sudden transit from one 'g' to hyper 'g', work to support the head and remain the relative position of head on trunk as common observed: i.e. in sudden acceleration or deceleration by car or ejection of pilot from aircraft. Accordingly it is highly possible that the neck muscle responses to moving up may be important to prevent the neck injury due to sudden linear acceleration such as moving up against gravity. However little is known about the evaluation of mechanism of this reflex. Therefore the present study was conducted with two aims. The first aim was to investigate the neck muscle responses to vertical linear acceleration bv 0.4 g produced with an electro-hydraulic servo-system. We chose the vertical linear acceleration because it activates mainly sacculus, from which afferents have been demonstrated to be connected directly to sternocleidomastoid muscle in animals and human. The second aim was to determine whether there is a difference of neck muscle response to moving down and moving up.

Accelerator Generation and Thermal Separation (AGATS) of Technetium-99m

ScienceCinema

Grover, Blaine

2018-05-01

Accelerator Generation and Thermal Separation (AGATS) of Technetium-99m is a linear electron accelerator-based technology for producing medical imaging radioisotopes from a separation process that heats, vaporizes and condenses the desired radioisotope. You can learn more about INL's education programs at http://www.facebook.com/idahonationallaboratory.

Acceleration of a trailing positron bunch in a plasma wakefield accelerator

DOE PAGES

Doche, A.; Beekman, C.; Corde, S.; ...

2017-10-27

High gradients of energy gain and high energy efficiency are necessary parameters for compact, cost-efficient and high-energy particle colliders. Plasma Wakefield Accelerators (PWFA) offer both, making them attractive candidates for next-generation colliders. Here in these devices, a charge-density plasma wave is excited by an ultra-relativistic bunch of charged particles (the drive bunch). The energy in the wave can be extracted by a second bunch (the trailing bunch), as this bunch propagates in the wake of the drive bunch. While a trailing electron bunch was accelerated in a plasma with more than a gigaelectronvolt of energy gain, accelerating a trailing positronmore » bunch in a plasma is much more challenging as the plasma response can be asymmetric for positrons and electrons. We report the demonstration of the energy gain by a distinct trailing positron bunch in a plasma wakefield accelerator, spanning nonlinear to quasi-linear regimes, and unveil the beam loading process underlying the accelerator energy efficiency. A positron bunch is used to drive the plasma wake in the experiment, though the quasi-linear wake structure could as easily be formed by an electron bunch or a laser driver. Finally, the results thus mark the first acceleration of a distinct positron bunch in plasma-based particle accelerators.« less

Acceleration of a trailing positron bunch in a plasma wakefield accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doche, A.; Beekman, C.; Corde, S.

High gradients of energy gain and high energy efficiency are necessary parameters for compact, cost-efficient and high-energy particle colliders. Plasma Wakefield Accelerators (PWFA) offer both, making them attractive candidates for next-generation colliders. Here in these devices, a charge-density plasma wave is excited by an ultra-relativistic bunch of charged particles (the drive bunch). The energy in the wave can be extracted by a second bunch (the trailing bunch), as this bunch propagates in the wake of the drive bunch. While a trailing electron bunch was accelerated in a plasma with more than a gigaelectronvolt of energy gain, accelerating a trailing positronmore » bunch in a plasma is much more challenging as the plasma response can be asymmetric for positrons and electrons. We report the demonstration of the energy gain by a distinct trailing positron bunch in a plasma wakefield accelerator, spanning nonlinear to quasi-linear regimes, and unveil the beam loading process underlying the accelerator energy efficiency. A positron bunch is used to drive the plasma wake in the experiment, though the quasi-linear wake structure could as easily be formed by an electron bunch or a laser driver. Finally, the results thus mark the first acceleration of a distinct positron bunch in plasma-based particle accelerators.« less

The algorithm for duration acceleration of repetitive projects considering the learning effect

NASA Astrophysics Data System (ADS)

Chen, Hongtao; Wang, Keke; Du, Yang; Wang, Liwan

2018-03-01

Repetitive project optimization problem is common in project scheduling. Repetitive Scheduling Method (RSM) has many irreplaceable advantages in the field of repetitive projects. As the same or similar work is repeated, the proficiency of workers will be correspondingly low to high, and workers will gain experience and improve the efficiency of operations. This is learning effect. Learning effect is one of the important factors affecting the optimization results in repetitive project scheduling. This paper analyzes the influence of the learning effect on the controlling path in RSM from two aspects: one is that the learning effect changes the controlling path, the other is that the learning effect doesn't change the controlling path. This paper proposes corresponding methods to accelerate duration for different types of critical activities and proposes the algorithm for duration acceleration based on the learning effect in RSM. And the paper chooses graphical method to identity activities' types and considers the impacts of the learning effect on duration. The method meets the requirement of duration while ensuring the lowest acceleration cost. A concrete bridge construction project is given to verify the effectiveness of the method. The results of this study will help project managers understand the impacts of the learning effect on repetitive projects, and use the learning effect to optimize project scheduling.

Plasma block acceleration based upon the interaction between double targets and an ultra-intense linearly polarized laser pulse

NASA Astrophysics Data System (ADS)

Xu, Yanxia; Wang, Jiaxiang; Hora, Heinrich; Qi, Xin; Xing, Yifan; Yang, Lei; Zhu, Wenjun

2018-04-01

A new scheme of plasma block acceleration based upon the interaction between double targets and an ultra-intense linearly polarized laser pulse with intensity I ˜ 1022 W/cm2 is investigated via two-dimensional particle-in-cell simulations. The targets are composed of a pre-target of low-density aluminium plasma and an overdense main-target of hydrogen plasma. Through intensive parameter optimization, we have observed highly efficient plasma block accelerations with a monochromatic proton beam peaked at GeVs. The underlying mechanism is attributed to the enhancement of the charge separation field due to the properly selected pre-target.

QALMA: A computational toolkit for the analysis of quality protocols for medical linear accelerators in radiation therapy

NASA Astrophysics Data System (ADS)

Rahman, Md Mushfiqur; Lei, Yu; Kalantzis, Georgios

2018-01-01

Quality Assurance (QA) for medical linear accelerator (linac) is one of the primary concerns in external beam radiation Therapy. Continued advancements in clinical accelerators and computer control technology make the QA procedures more complex and time consuming which often, adequate software accompanied with specific phantoms is required. To ameliorate that matter, we introduce QALMA (Quality Assurance for Linac with MATLAB), a MALAB toolkit which aims to simplify the quantitative analysis of QA for linac which includes Star-Shot analysis, Picket Fence test, Winston-Lutz test, Multileaf Collimator (MLC) log file analysis and verification of light & radiation field coincidence test.

Effect of dynamic factors of space flights on the green alga Chlorella vulgaris.

PubMed

Moskvitin, E V; Vaulina, E N

1974-01-01

The biological effects of vibrational and linear acceleration on the alga Chlorella vulgaris were studied. Periodic vibration in the frequency range of 4-4000 Hz with vibrational acceleration up to 16 g did not affect the survival and mutability of Chlorella cells and did not modify the effects of acute gamma-radiation. However, random vibration similar to that occurring during launch of spaceships, combined with linear acceleration increased the radiation damage to algae produced by acute gamma-radiation at a dose of 10000 r. This effect is seen only in cells at the beginning of the G1 stage, which precedes DNA synthesis.

Preliminary design of a high-intensity continuous-wave deuteron RFQ

NASA Astrophysics Data System (ADS)

Liu, X.; Kamigaito, O.; Sakamoto, N.; Yamada, K.

2017-07-01

A high-intensity deuteron linear accelerator is currently being studied as a promising candidate to treat high-level radioactive waste through the nuclear transmutation process. This paper presents the study on a design of a 75.5 MHz, 400 mA, continuous-wave deuteron radio-frequency quadrupole (RFQ), which is proposed as the front-end of such a linear accelerator. The results of the beam dynamics simulation suggest that the designed RFQ can accelerate a 400-mA deuteron beam from 100 keV to 2.5 MeV with a transmission rate of 92.0 ∼ 93.3%, depending on the assumed input transverse emittance.

Community Project for Accelerator Science and Simulation (ComPASS) Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cary, John R.; Cowan, Benjamin M.; Veitzer, S. A.

2016-03-04

Tech-X participated across the full range of ComPASS activities, with efforts in the Energy Frontier primarily through modeling of laser plasma accelerators and dielectric laser acceleration, in the Intensity Frontier primarily through electron cloud modeling, and in Uncertainty Quantification being applied to dielectric laser acceleration. In the following we present the progress and status of our activities for the entire period of the ComPASS project for the different areas of Energy Frontier, Intensity Frontier and Uncertainty Quantification.

High Intensity Proton Accelerator Project in Japan (J-PARC).

PubMed

Tanaka, Shun-ichi

2005-01-01

The High Intensity Proton Accelerator Project, named as J-PARC, was started on 1 April 2001 at Tokai-site of JAERI. The accelerator complex of J-PARC consists of three accelerators: 400 MeV Linac, 3 GeV rapid cycle synchrotron and 50 GeV synchrotron; and four major experimental facilities: Material and Life Science Facility, Nuclear and Particle Physics Facility, Nuclear Transmutation Experiment Facility and Neutrino Facility. The outline of the J-PARC is presented with the current status of construction.

The evaluation of speed skating helmet performance through peak linear and rotational accelerations.

PubMed

Karton, Clara; Rousseau, Philippe; Vassilyadi, Michael; Hoshizaki, Thomas Blaine

2014-01-01

Like many sports involving high speeds and body contact, head injuries are a concern for short track speed skating athletes and coaches. While the mandatory use of helmets has managed to nearly eliminate catastrophic head injuries such as skull fractures and cerebral haemorrhages, they may not be as effective at reducing the risk of a concussion. The purpose of this study was to evaluate the performance characteristics of speed skating helmets with respect to managing peak linear and peak rotational acceleration, and to compare their performance against other types of helmets commonly worn within the speed skating sport. Commercially available speed skating, bicycle and ice hockey helmets were evaluated using a three-impact condition test protocol at an impact velocity of 4 m/s. Two speed skating helmet models yielded mean peak linear accelerations at a low-estimated probability range for sustaining a concussion for all three impact conditions. Conversely, the resulting mean peak rotational acceleration values were all found close to the high end of a probability range for sustaining a concussion. A similar tendency was observed for the bicycle and ice hockey helmets under the same impact conditions. Speed skating helmets may not be as effective at managing rotational acceleration and therefore may not successfully protect the user against risks associated with concussion injuries.

A neutron track etch detector for electron linear accelerators in radiotherapy

PubMed Central

Vukovic, Branko; Faj, Dario; Poje, Marina; Varga, Maja; Radolic, Vanja; Miklavcic, Igor; Ivkovic, Ana; Planinic, Josip

2010-01-01

Background Electron linear accelerators in medical radiotherapy have replaced cobalt and caesium sources of radiation. However, medical accelerators with photon energies over 10 MeV generate undesired fast neutron contamination in a therapeutic X-ray photon beam. Photons with energies above 10 MeV can interact with the atomic nucleus of a high-Z material, of which the target and the head of an accelerator consist, and lead to the neutron ejection. Results and conclusions. Our neutron dosimeter, composed of the LR-115 track etch detector and boron foil BN-1 converter, was calibrated on thermal neutrons generated in the nuclear reactor of the Josef Stefan Institute (Slovenia), and applied to dosimetry of undesirable neutrons in photon radiotherapy by the linear accelerator 15 MV Siemens Mevatron. Having considered a high dependence of a cross-section between neutron and boron on neutron energy, and broad neutron spectrum in a photon beam, as well as outside the entrance door to maze of the Mevatron, we developed a method for determining the effective neutron detector response. A neutron dose rate in the photon beam was measured to be 1.96 Sv/h. Outside the Mevatron room the neutron dose rate was 0.62 μSv/h. PACS: 87.52. Ga; 87.53.St; 29.40.Wk. PMID:22933893

Acceleration lane design for higher truck volumes.

DOT National Transportation Integrated Search

2008-12-09

The research project examined attributes associated with tractor-trailer trucks accelerating on freeway entry ramps and : entering the main traffic lanes. Data for this project were collected at five commercial vehicle weigh stations in : Arkansas an...

Orbit correction in a linear nonscaling fixed field alternating gradient accelerator

DOE PAGES

Kelliher, D. J.; Machida, S.; Edmonds, C. S.; ...

2014-11-20

In a linear non-scaling FFAG the large natural chromaticity of the machine results in a betatron tune that varies by several integers over the momentum range. In addition, orbit correction is complicated by the consequent variation of the phase advance between lattice elements. Here we investigate how the correction of multiple closed orbit harmonics allows correction of both the COD and the accelerated orbit distortion over the momentum range.

Magnetic Linear Accelerator (MAGLAC) as Driver for Impact Fusion (IF)

DTIC Science & Technology

1979-07-01

qualitatively different. For example, a superconductor levitated by Meis- sner effect ("flux exculsion") would be vertically stable for z > a/2; an iron...These include, for example, 1. Further material research on superconductors under high magnetic field and high frequencies. 2. Theoretical and...DEFENSE PENTAGON IMSHJNGT0N5& 20301-7100 £?1C ^ALITY INSPECTED 4 This paper presents considerations on the design of a magnetic linear accelerator

Linear induction accelerator and pulse forming networks therefor

DOEpatents

Buttram, Malcolm T.; Ginn, Jerry W.

1989-01-01

A linear induction accelerator includes a plurality of adder cavities arranged in a series and provided in a structure which is evacuated so that a vacuum inductance is provided between each adder cavity and the structure. An energy storage system for the adder cavities includes a pulsed current source and a respective plurality of bipolar converting networks connected thereto. The bipolar high-voltage, high-repetition-rate square pulse train sets and resets the cavities.

When is quasi-linear theory exact. [particle acceleration

NASA Technical Reports Server (NTRS)

Jones, F. C.; Birmingham, T. J.

1975-01-01

We use the cumulant expansion technique of Kubo (1962, 1963) to derive an integrodifferential equation for the average one-particle distribution function for particles being accelerated by electric and magnetic fluctuations of a general nature. For a very restricted class of fluctuations, the equation for this function degenerates exactly to a differential equation of Fokker-Planck type. Quasi-linear theory, including the adiabatic assumption, is an exact theory only for this limited class of fluctuations.

The influence of air humidity on an unsealed ionization chamber in a linear accelerator.

PubMed

Blad, B; Nilsson, P; Knöös, T

1996-11-01

The safe and accurate delivery of the prescribed absorbed dose is the central function of the dose monitoring and beam stabilization system in a medical linear accelerator. The absorbed dose delivered to the patient during radiotherapy is often monitored by a transmission ionization chamber. Therefore it is of utmost importance that the chamber behaves correctly. We have noticed that the sensitivity of an unsealed chamber in a Philips SL linear accelerator changes significantly, especially during and after the summer season. The reason for this is probably a corrosion effect of the conductive plates in the chamber due to the increased relative humidity during hot periods. We have found that the responses of the different ion chamber plates change with variations in air humidity and that they do not return to their original values when the air humidity is returned to ambient conditions.

The vortex as a clock

NASA Astrophysics Data System (ADS)

Breidenthal, Robert

2003-11-01

Using heuristic arguments, the fundamental effect of acceleration on dissipation in self-similar turbulence is explored. If the ratio of the next vortex rotation period to the last one is always constant, a flow is temporally self-similar. This implies that the vortex rotation period is a linear function of time. For ordinary, unforced turbulence, the period increases linearly in time. However, by imposing an external e-folding time scale on the flow that decreases linearly in time, the dissipation rate is changed from that of the corresponding unforced flow. The dissipation rate depends on the time rate of change of the rotation period as well as the dimensions of the dynamic quantity controlling the flow. For almost all canonical laboratory flows, acceleration reduces the dissipation and entrainment rates. An example is the exponential jet, where the flame length increases by about 20conventional jet. An exception is Rayleigh-Taylor flow, where acceleration increases the dissipation rate.

Detection of infrasound and linear acceleration in fishes.

PubMed

Sand, O; Karlsen, H E

2000-09-29

Fishes have an acute sensitivity to extremely low-frequency linear acceleration, or infrasound, even down to below 1 Hz. The otolith organs are the sensory system responsible for this ability. The hydrodynamic noise generated by swimming fishes is mainly in the infrasound range, and may be important in courtship and prey predator interactions. Intense infrasound has a deterring effect on some species, and has a potential in acoustic barriers. We hypothesize that the pattern of ambient infrasound in the oceans may be used for orientation in migratory fishes, and that pelagic fishes may detect changes in the surface wave pattern associated with altered water depth and distant land formations. We suggest that the acute sensitivity to linear acceleration could be used for inertial guidance, and to detect the relative velocity of layered ocean currents. Sensitivity to infrasound may be a widespread ability among aquatic organisms, and has also been reported in cephalopods and crustaceans.

Detection of infrasound and linear acceleration in fishes.

PubMed Central

Sand, O; Karlsen, H E

2000-01-01

Fishes have an acute sensitivity to extremely low-frequency linear acceleration, or infrasound, even down to below 1 Hz. The otolith organs are the sensory system responsible for this ability. The hydrodynamic noise generated by swimming fishes is mainly in the infrasound range, and may be important in courtship and prey predator interactions. Intense infrasound has a deterring effect on some species, and has a potential in acoustic barriers. We hypothesize that the pattern of ambient infrasound in the oceans may be used for orientation in migratory fishes, and that pelagic fishes may detect changes in the surface wave pattern associated with altered water depth and distant land formations. We suggest that the acute sensitivity to linear acceleration could be used for inertial guidance, and to detect the relative velocity of layered ocean currents. Sensitivity to infrasound may be a widespread ability among aquatic organisms, and has also been reported in cephalopods and crustaceans. PMID:11079418

Theory, simulation and experiments for precise deflection control of radiotherapy electron beams.

PubMed

Figueroa, R; Leiva, J; Moncada, R; Rojas, L; Santibáñez, M; Valente, M; Velásquez, J; Young, H; Zelada, G; Yáñez, R; Guillen, Y

2018-03-08

Conventional radiotherapy is mainly applied by linear accelerators. Although linear accelerators provide dual (electron/photon) radiation beam modalities, both of them are intrinsically produced by a megavoltage electron current. Modern radiotherapy treatment techniques are based on suitable devices inserted or attached to conventional linear accelerators. Thus, precise control of delivered beam becomes a main key issue. This work presents an integral description of electron beam deflection control as required for novel radiotherapy technique based on convergent photon beam production. Theoretical and Monte Carlo approaches were initially used for designing and optimizing device´s components. Then, dedicated instrumentation was developed for experimental verification of electron beam deflection due to the designed magnets. Both Monte Carlo simulations and experimental results support the reliability of electrodynamics models used to predict megavoltage electron beam control. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ion acceleration in a plasma focus

NASA Technical Reports Server (NTRS)

Gary, S. P.

1974-01-01

The electric and magnetic fields associated with anomalous diffusion to the axis of a linear plasma discharge are used to compute representative ion trajectories. Substantial axial acceleration of the ions is demonstrated.

External Beam Therapy (EBT)

MedlinePlus

... deliver the daily treatments. top of page What equipment is used? Radiation oncologists use linear accelerators or ... accelerator page top of page Who operates the equipment? The equipment is operated by a radiation therapist, ...

Feasibility study of basic characterization of MAGAT polymer gel using CBCT attached in linear accelerator: Preliminary study

NASA Astrophysics Data System (ADS)

Sathiyaraj, P.; Samuel, E. James jebaseelan

2018-01-01

The aim of this study is to evaluate the methacrylic acid, gelatin and tetrakis (hydroxymethyl) phosphonium chloride gel (MAGAT) by cone beam computed tomography (CBCT) attached with modern linear accelerator. To compare the results of standard diagnostic computed tomography (CT) with CBCT, different parameters such as linearity, sensitivity and temporal stability were checked. MAGAT gel showed good linearity for both diagnostic CT and CBCT measurements. Sensitivity and temporal stability were also comparable with diagnostic CT measurements. In both the modalities, the sensitivity of the MAGAT increased to 4 days and decreased till the 10th day of post irradiation. Since all measurements (linearity, sensitivity and temporal stability) from diagnostic CT and CBCT were comparable, CBCT could be a potential tool for dose analysis study for polymer gel dosimeter.

Beam transport results on the multi-beam MABE accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coleman, P.D.; Alexander, J.A.; Hasti, D.E.

1985-10-01

MABE is a multistage, electron beam linear accelerator. The accelerator has been operated in single beam (60 kA, 7 Mev) and multiple beam configurations. This paper deals with the multiple beam configuration in which typically nine approx. = 25 kA injected beams are transported through three accelerating gaps. Experimental results from the machine are discussed, including problems encountered and proposed solutions to those problems.

Accelerator Technology Division annual report, FY 1989

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-06-01

This paper discusses: accelerator physics and special projects; experiments and injectors; magnetic optics and beam diagnostics; accelerator design and engineering; radio-frequency technology; accelerator theory and simulation; free-electron laser technology; accelerator controls and automation; and high power microwave sources and effects.

Similar head impact acceleration measured using instrumented ear patches in a junior rugby union team during matches in comparison with other sports.

PubMed

King, Doug A; Hume, Patria A; Gissane, Conor; Clark, Trevor N

2016-07-01

OBJECTIVE Direct impact with the head and the inertial loading of the head have been postulated as major mechanisms of head-related injuries, such as concussion. METHODS This descriptive observational study was conducted to quantify the head impact acceleration characteristics in under-9-year-old junior rugby union players in New Zealand. The impact magnitude, frequency, and location were collected with a wireless head impact sensor that was worn by 14 junior rugby players who participated in 4 matches. RESULTS A total of 721 impacts > 10g were recorded. The median (interquartile range [IQR]) number of impacts per player was 46 (IQR 37-58), resulting in 10 (IQR 4-18) impacts to the head per player per match. The median impact magnitudes recorded were 15g (IQR 12g-21g) for linear acceleration and 2296 rad/sec(2) (IQR 1352-4152 rad/sec(2)) for rotational acceleration. CONCLUSIONS There were 121 impacts (16.8%) above the rotational injury risk limit and 1 (0.1%) impact above the linear injury risk limit. The acceleration magnitude and number of head impacts in junior rugby union players were higher than those previously reported in similar age-group sports participants. The median linear acceleration for the under-9-year-old rugby players were similar to 7- to 8-year-old American football players, but lower than 9- to 12-year-old youth American football players. The median rotational accelerations measured were higher than the median and 95th percentiles in youth, high school, and collegiate American football players.

High Resolution BPM Upgrade for the ATF Damping Ring at KEK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eddy, N.; Briegel, C.; Fellenz, B.

2011-08-17

A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital down-conversion techniques, digital signal processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented. The next generation of linear colliders require ultra-low vertical emittance of <2 pm-rad. The damping ring at the KEK Accelerator Test Facilitymore » (ATF) is designed to demonstrate this mission critical goal. A high resolution beam position monitor (BPM) system for the damping ring is one of the key tools for realizing this goal. The BPM system needs to provide two distnict measurements. First, a very high resolution ({approx}100-200nm) closed-orbit measurement which is averaged over many turns and realized with narrowband filter techniques - 'narrowband mode'. This is needed to monitor and steer the beam along an optimum orbit and to facilitate beam-based alignment to minimize non-linear field effects. Second, is the ability to make turn by turn (TBT) measurements to support optics studies and corrections necessary to achieve the design performance. As the TBT measurement necessitates a wider bandwidth, it is often referred to as 'wideband mode'. The BPM upgrade was initiated as a KEK/SLAC/FNAL collaboration in the frame of the Global Design Initiative of the International Linear Collider. The project was realized and completed using Japan-US funds with Fermilab as the core partner.« less

Spectroscopy of baryon resonances

NASA Astrophysics Data System (ADS)

Beck, Reinhard; Thoma, Ulrike

2017-01-01

Within project A.1 of the SFB/TR16 "Subnuclear Structure of Matter", a large amount of data on photoproduction reactions has been accumulated at the Bonn Electron Stretcher Accelerator ELSA with the CBELSA/TAPS detector and was analysed in detail. In particular, data have been taken with unpolarized or with linearly or circularly polarized photons and with unpolarized or with longitudinally or transversely polarized protons. Photoproduction off neutrons was studied to determine the helicity amplitudes for the excitation of resonances off neutrons. In a partial wave analysis of the data, new resonances have been found and the properties of new and of known resonances have been determined, including the measurement of partial widths of so far unmeasured decay modes.

UTDallas Offline Computing System for B Physics with the Babar Experiment at SLAC

NASA Astrophysics Data System (ADS)

Benninger, Tracy L.

1998-10-01

The University of Texas at Dallas High Energy Physics group is building a high performance, large storage computing system for B physics research with the BaBar experiment (``factory'') at the Stanford Linear Accelerator Center. The goal of this system is to analyze one terabyte of complex Event Store data from BaBar in one to two days. The foundation of the computing system is a Sun E6000 Enterprise multiprocessor system, with additions of a Sun StorEdge L1800 Tape Library, a Sun Workstation for processing batch jobs, staging disks and interface cards. The design considerations, current status, projects underway, and possible upgrade paths will be discussed.

EuCARD2: enhanced accelerator research and development in Europe

NASA Astrophysics Data System (ADS)

Romaniuk, Ryszard S.

2013-10-01

Accelerator science and technology is one of a key enablers of the developments in the particle physic, photon physics and also applications in medicine and industry. EuCARD2 is an European research project which will be realized during 2013-2017 inside the EC FP7 framework. The project concerns the development and coordination of European Accelerator Research and Development. The project is particularly important, to a number of domestic laboratories, due to some plans to build large accelerator infrastructure in Poland. Large accelerator infrastructure of fundamental and applied research character stimulates around it the development and industrial applications as well as biomedical of advanced accelerators, material research and engineering, cryo-technology, mechatronics, robotics, and in particular electronics - like networked measurement and control systems, sensors, computer systems, automation and control systems. The paper presents a digest of the European project EuCARD2 which is Enhanced European Coordination for Accelerator Research and Development. The paper presents a digest of the research results and assumptions in the domain of accelerator science and technology in Europe, shown during the final fourth annual meeting of the EuCARD - European Coordination of Accelerator R&D, and the kick-off meeting of the EuCARD2. There are debated a few basic groups of accelerator systems components like: measurement - control networks of large geometrical extent, multichannel systems for large amounts of metrological data acquisition, precision photonic networks of reference time, frequency and phase distribution, high field magnets, superconducting cavities, novel beam collimators, etc. The paper bases on the following materials: Internet and Intranet documents combined with EuCARD2, Description of Work FP7 EuCARD-2 DoW-312453, 2013-02-13, and discussions and preparatory materials worked on by Eucard-2 initiators.

Covariant Uniform Acceleration

NASA Astrophysics Data System (ADS)

Friedman, Yaakov; Scarr, Tzvi

2013-04-01

We derive a 4D covariant Relativistic Dynamics Equation. This equation canonically extends the 3D relativistic dynamics equation , where F is the 3D force and p = m0γv is the 3D relativistic momentum. The standard 4D equation is only partially covariant. To achieve full Lorentz covariance, we replace the four-force F by a rank 2 antisymmetric tensor acting on the four-velocity. By taking this tensor to be constant, we obtain a covariant definition of uniformly accelerated motion. This solves a problem of Einstein and Planck. We compute explicit solutions for uniformly accelerated motion. The solutions are divided into four Lorentz-invariant types: null, linear, rotational, and general. For null acceleration, the worldline is cubic in the time. Linear acceleration covariantly extends 1D hyperbolic motion, while rotational acceleration covariantly extends pure rotational motion. We use Generalized Fermi-Walker transport to construct a uniformly accelerated family of inertial frames which are instantaneously comoving to a uniformly accelerated observer. We explain the connection between our approach and that of Mashhoon. We show that our solutions of uniformly accelerated motion have constant acceleration in the comoving frame. Assuming the Weak Hypothesis of Locality, we obtain local spacetime transformations from a uniformly accelerated frame K' to an inertial frame K. The spacetime transformations between two uniformly accelerated frames with the same acceleration are Lorentz. We compute the metric at an arbitrary point of a uniformly accelerated frame. We obtain velocity and acceleration transformations from a uniformly accelerated system K' to an inertial frame K. We introduce the 4D velocity, an adaptation of Horwitz and Piron s notion of "off-shell." We derive the general formula for the time dilation between accelerated clocks. We obtain a formula for the angular velocity of a uniformly accelerated object. Every rest point of K' is uniformly accelerated, and its acceleration is a function of the observer's acceleration and its position. We obtain an interpretation of the Lorentz-Abraham-Dirac equation as an acceleration transformation from K' to K.

Mass perturbation techniques for tuning and decoupling of a Disk Resonator Gyroscope

NASA Astrophysics Data System (ADS)

Schwartz, David

Axisymmetric microelectromechanical (MEM) vibratory rate gyroscopes are designed so that the two Coriolis-coupled modes exploited for rate sensing possess equal modal frequencies and so that the central post which attaches the resonator to the sensor case is a nodal point of the these two modes. The former quality maximizes the signal-to-noise ratio of the sensor, while the latter quality eliminates any coupling of linear acceleration to the modes of interest, which, if present, creates spurious rate signals in response to linear vibration of the sensor case. When the gyro resonators are fabricated, however, small mass and stiffness asymmetries cause the frequencies of the two modes to deviate from each other and couple these modes to linear acceleration. In a resonator post-fabrication step, these effects can be reduced by altering the mass distribution of the resonator. In this dissertation, a scale model of the axisymmetric resonator of the Disk Resonator Gyroscope (DRG) is used to develop and test methods that successfully reduce frequency detuning (Part I) and linear acceleration coupling (Part II) through guided mass perturbations.

Generation of virtual monochromatic CBCT from dual kV/MV beam projections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hao; Liu, Bo; Yin, Fang-Fang, E-mail: fangfang.yin@duke.edu

Purpose: To develop a novel on-board imaging technique which allows generation of virtual monochromatic (VM) cone-beam CT (CBCT) with a selected energy from combined kilovoltage (kV)/megavoltage (MV) beam projections. Methods: With the current orthogonal kV/MV imaging hardware equipped in modern linear accelerators, both MV projections (from gantry angle of 0°–100°) and kV projections (90°–200°) were acquired as gantry rotated a total of 110°. A selected range of overlap projections between 90° to 100° were then decomposed into two material projections using experimentally determined parameters from orthogonally stacked aluminum and acrylic step-wedges. Given attenuation coefficients of aluminum and acrylic at amore » predetermined energy, one set of VM projections could be synthesized from two corresponding sets of decomposed projections. Two linear functions were generated using projection information at overlap angles to convert kV and MV projections at nonoverlap angles to approximate VM projections for CBCT reconstruction. The contrast-to-noise ratios (CNRs) were calculated for different inserts in VM CBCTs of a CatPhan phantom with various selected energies and compared with those in kV and MV CBCTs. The effect of overlap projection number on CNR was evaluated. Additionally, the effect of beam orientation was studied by scanning the CatPhan sandwiched with two 5 cm solid-water phantoms on both lateral sides and an electronic density phantom with two metal bolt inserts. Results: Proper selection of VM energy [30 and 40 keV for low-density polyethylene (LDPE), polymethylpentene, 2 MeV for Delrin] provided comparable or even better CNR results as compared with kV or MV CBCT. An increased number of overlap kV and MV projection demonstrated only marginal improvements of CNR for different inserts (with the exception of LDPE) and therefore one projection overlap was found to be sufficient for the CatPhan study. It was also evident that the optimal CBCT image quality was achieved when MV beams penetrated through the heavy attenuation direction of the object. Conclusions: A novel technique was developed to generate VM CBCTs from kV/MV projections. This technique has the potential to improve CNR at selected VM energies and to suppress artifacts at appropriate beam orientations.« less

Generation of virtual monochromatic CBCT from dual kV/MV beam projections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hao; Liu, Bo; Yin, Fang-Fang, E-mail: fangfang.yin@duke.edu

2013-12-15

Purpose: To develop a novel on-board imaging technique which allows generation of virtual monochromatic (VM) cone-beam CT (CBCT) with a selected energy from combined kilovoltage (kV)/megavoltage (MV) beam projections. Methods: With the current orthogonal kV/MV imaging hardware equipped in modern linear accelerators, both MV projections (from gantry angle of 0°–100°) and kV projections (90°–200°) were acquired as gantry rotated a total of 110°. A selected range of overlap projections between 90° to 100° were then decomposed into two material projections using experimentally determined parameters from orthogonally stacked aluminum and acrylic step-wedges. Given attenuation coefficients of aluminum and acrylic at amore » predetermined energy, one set of VM projections could be synthesized from two corresponding sets of decomposed projections. Two linear functions were generated using projection information at overlap angles to convert kV and MV projections at nonoverlap angles to approximate VM projections for CBCT reconstruction. The contrast-to-noise ratios (CNRs) were calculated for different inserts in VM CBCTs of a CatPhan phantom with various selected energies and compared with those in kV and MV CBCTs. The effect of overlap projection number on CNR was evaluated. Additionally, the effect of beam orientation was studied by scanning the CatPhan sandwiched with two 5 cm solid-water phantoms on both lateral sides and an electronic density phantom with two metal bolt inserts. Results: Proper selection of VM energy [30 and 40 keV for low-density polyethylene (LDPE), polymethylpentene, 2 MeV for Delrin] provided comparable or even better CNR results as compared with kV or MV CBCT. An increased number of overlap kV and MV projection demonstrated only marginal improvements of CNR for different inserts (with the exception of LDPE) and therefore one projection overlap was found to be sufficient for the CatPhan study. It was also evident that the optimal CBCT image quality was achieved when MV beams penetrated through the heavy attenuation direction of the object. Conclusions: A novel technique was developed to generate VM CBCTs from kV/MV projections. This technique has the potential to improve CNR at selected VM energies and to suppress artifacts at appropriate beam orientations.« less

The adequate stimulus for mammalian linear vestibular evoked potentials (VsEPs)

PubMed Central

Jones, Timothy A.; Jones, Sherri M.; Vijayakumar, Sarath; Brugeaud, Aurore; Bothwell, Marcella; Chabbert, Christian

2013-01-01

Short latency linear vestibular sensory evoked potentials (VsEPs) provide a means to objectively and directly assess the function of gravity receptors in mammals and birds. The importance of this functional measure is illustrated by its use in studies of the genetic basis of vestibular function and disease. Head motion is the stimulus for the VsEP. In the bird, it has been established that neurons mediating the linear VsEP respond collectively to the rate of change in linear acceleration during head movement (i.e. jerk) rather than peak acceleration. The kinematic element of motion responsible for triggering mammalian VsEPs has not been characterized in detail. Here we tested the hypothesis that jerk is the kinematic component of head motion responsible for VsEP characteristics. VsEP amplitudes and latencies changed systematically when peak acceleration level was held constant and jerk level was varied from ~0.9 to 4.6 g/ms. In contrast, responses remained relatively constant when kinematic jerk was held constant and peak acceleration was varied from ~0.9 to 5.5g in mice and ~0.44 to 2.75g in rats. Thus the mammalian VsEP depends on jerk levels and not peak acceleration. We conclude that kinematic jerk is the adequate stimulus for the mammalian VsEP. This sheds light on the behavior of neurons generating the response. The results also provide the basis for standardizing the reporting of stimulus levels, which is key to ensuring that response characteristics reported in the literature by many laboratories can be effectively compared and interpreted. PMID:21664446

The status and road map of Turkish Accelerator Center (TAC)

NASA Astrophysics Data System (ADS)

Yavaş, Ö.

2012-02-01

Turkish Accelerator Center (TAC) project is supported by the State Planning Organization (SPO) of Turkey and coordinated by Ankara University. After having completed the Feasibility Report (FR) in 2000 and the Conceptual Design Report (CDR) in 2005, third phase of the project started in 2006 as an inter-universities project including ten Turkish Universities with the support of SPO. Third phase of the project has two main scientific goals: to prepare the Technical Design Report (TDR) of TAC and to establish an Infrared Free Electron Laser (IR FEL) facility, named as Turkish Accelerator and Radiation Laboratory at Ankara (TARLA) as a first step. The facility is planned to be completed in 2015 and will be based on 15-40 MeV superconducting linac. In this paper, main aims, national and regional importance, main parts main parameters, status and road map of Turkish Accelerator Center will be presented.

SuperB Progress Report for Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biagini, M.E.; Boni, R.; Boscolo, M.

2012-02-14

This report details the progress made in by the SuperB Project in the area of the Collider since the publication of the SuperB Conceptual Design Report in 2007 and the Proceedings of SuperB Workshop VI in Valencia in 2008. With this document we propose a new electron positron colliding beam accelerator to be built in Italy to study flavor physics in the B-meson system at an energy of 10 GeV in the center-of-mass. This facility is called a high luminosity B-factory with a project name 'SuperB'. This project builds on a long history of successful e+e- colliders built around themore » world, as illustrated in Figure 1.1. The key advances in the design of this accelerator come from recent successes at the DAFNE collider at INFN in Frascati, Italy, at PEP-II at SLAC in California, USA, and at KEKB at KEK in Tsukuba Japan, and from new concepts in beam manipulation at the interaction region (IP) called 'crab waist'. This new collider comprises of two colliding beam rings, one at 4.2 GeV and one at 6.7 GeV, a common interaction region, a new injection system at full beam energies, and one of the two beams longitudinally polarized at the IP. Most of the new accelerator techniques needed for this collider have been achieved at other recently completed accelerators including the new PETRA-3 light source at DESY in Hamburg (Germany) and the upgraded DAFNE collider at the INFN laboratory at Frascati (Italy), or during design studies of CLIC or the International Linear Collider (ILC). The project is to be designed and constructed by a worldwide collaboration of accelerator and engineering staff along with ties to industry. To save significant construction costs, many components from the PEP-II collider at SLAC will be recycled and used in this new accelerator. The interaction region will be designed in collaboration with the particle physics detector to guarantee successful mutual use. The accelerator collaboration will consist of several groups at present universities and national laboratories. In Italy these may include INFN Frascati and the University of Pisa, in the United States SLAC, LBNL, BNL and several universities, in France IN2P3, LAPP, and Grenoble, in Russia BINP, in Poland Krakow University, and in the UK the Cockcroft Institute. The construction time for this collider is a total of about four years. The new tunnel can be bored in about a year. The new accelerator components can be built and installed in about 4 years. The shipping of components from PEP-II at SLAC to Italy will take about a year. A new linac and damping ring complex for the injector for the rings can be built in about three years. The commissioning of this new accelerator will take about a year including the new electron and positron sources, new linac, new damping ring, new beam transport lines, two new collider rings and the Interaction Region. The new particle physics detector can be commissioned simultaneously with the accelerator. Once beam collisions start for particle physics, the luminosity will increase with time, likely reaching full design specifications after about two to three years of operation. After construction, the operation of the collider will be the responsibility of the Italian INFN governmental agency. The intent is to run this accelerator about ten months each year with about one month for accelerator turn-on and nine months for colliding beams. The collider will need to operate for about 10 years to provide the required 50 ab{sup -1} requested by the detector collaboration. Both beams as anticipated in this collider will have properties that are excellent for use as sources for synchrotron radiation (SR). The expected photon properties are comparable to those of PETRA-3 or NSLS-II. The beam lines and user facilities needed to carry out this SR program are being investigated.« less

First results of 28 GHz superconducting electron cyclotron resonance ion source for KBSI accelerator.

PubMed

Park, Jin Yong; Lee, Byoung-Seob; Choi, Seyong; Kim, Seong Jun; Ok, Jung-Woo; Yoon, Jang-Hee; Kim, Hyun Gyu; Shin, Chang Seouk; Hong, Jonggi; Bahng, Jungbae; Won, Mi-Sook

2016-02-01

The 28 GHz superconducting electron cyclotron resonance (ECR) ion source has been developed to produce a high current heavy ion for the linear accelerator at KBSI (Korea Basic Science Institute). The objective of this study is to generate fast neutrons with a proton target via a p(Li,n)Be reaction. The design and fabrication of the essential components of the ECR ion source, which include a superconducting magnet with a liquid helium re-condensed cryostat and a 10 kW high-power microwave, were completed. The waveguide components were connected with a plasma chamber including a gas supply system. The plasma chamber was inserted into the warm bore of the superconducting magnet. A high voltage system was also installed for the ion beam extraction. After the installation of the ECR ion source, we reported the results for ECR plasma ignition at ECRIS 2014 in Russia. Following plasma ignition, we successfully extracted multi-charged ions and obtained the first results in terms of ion beam spectra from various species. This was verified by a beam diagnostic system for a low energy beam transport system. In this article, we present the first results and report on the current status of the KBSI accelerator project.

First results of 28 GHz superconducting electron cyclotron resonance ion source for KBSI accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Jin Yong; Lee, Byoung-Seob; Choi, Seyong

The 28 GHz superconducting electron cyclotron resonance (ECR) ion source has been developed to produce a high current heavy ion for the linear accelerator at KBSI (Korea Basic Science Institute). The objective of this study is to generate fast neutrons with a proton target via a p(Li,n)Be reaction. The design and fabrication of the essential components of the ECR ion source, which include a superconducting magnet with a liquid helium re-condensed cryostat and a 10 kW high-power microwave, were completed. The waveguide components were connected with a plasma chamber including a gas supply system. The plasma chamber was inserted intomore » the warm bore of the superconducting magnet. A high voltage system was also installed for the ion beam extraction. After the installation of the ECR ion source, we reported the results for ECR plasma ignition at ECRIS 2014 in Russia. Following plasma ignition, we successfully extracted multi-charged ions and obtained the first results in terms of ion beam spectra from various species. This was verified by a beam diagnostic system for a low energy beam transport system. In this article, we present the first results and report on the current status of the KBSI accelerator project.« less

Alternating phase focused linacs

DOEpatents

Swenson, Donald A.

1980-01-01

A heavy particle linear accelerator employing rf fields for transverse and ongitudinal focusing as well as acceleration. Drift tube length and gap positions in a standing wave drift tube loaded structure are arranged so that particles are subject to acceleration and succession of focusing and defocusing forces which contain the beam without additional magnetic or electric focusing fields.

Acceleration-Augmented LQG Control of an Active Magnetic Bearing

NASA Technical Reports Server (NTRS)

Feeley, Joseph J.

1993-01-01

A linear-quadratic-gaussian (LQG) regulator controller design for an acceleration-augmented active magnetic bearing (AMB) is outlined. Acceleration augmentation is a key feature in providing improved dynamic performance of the controller. The optimal control formulation provides a convenient method of trading-off fast transient response and force attenuation as control objectives.

EH 11n modes E type in the disk and washer accelerating structure

NASA Astrophysics Data System (ADS)

Andreev, V. G.; Belugin, V. M.; Daikovsky, A. G.; Esin, S. K.; Kravchuk, L. V.; Paramonov, V. V.; Ryabov, A. D.

1983-01-01

The disk and washer accelerating structure has a great deal to do with high-beta structures progress. The frequencies and electromagnetic fields for modes, which have a different number of azimuthal variations, are calculated to determined the dispersion properties and other characteristics of parasitic modes in a disc and washer accelerating structure. The main attention was given to the accelerating structure of the linear accelerator of the Institute for Nuclear Research (INR) of the USSR Academy of Sciences. Modification of a structure for PIGMI accelerator (LANL, USA) is considered briefly.

Shielding evaluation for IMRT implementation in an existing accelerator vault

PubMed Central

Price, R. A.; Chibani, O.; Ma, C.‐M.

2003-01-01

A formalism is developed for evaluating the shielding in an existing vault to be used for IMRT. Existing exposure rate measurements are utilized as well as a newly developed effective modulation scaling factor. Examples are given for vaults housing 6, 10 and 18 MV linear accelerators. The use of an 18 MV Siemens linear accelerator is evaluated for IMRT delivery with respect to neutron production and the effects on individual patients. A modified modulation scaling factor is developed and the risk of the incurrence of fatal secondary malignancies is estimated. The difference in neutron production between 18 MV Varian and Siemens accelerators is estimated using Monte Carlo results. The neutron production from the Siemens accelerator is found to be approximately 4 times less than that of the Varian accelerator resulting in a risk of fatal secondary malignancy occurrence of approximately 1.6% when using the SMLC delivery technique and our measured modulation scaling factors. This compares with a previously published value of 1.6% for routine 3D CRT delivery on the Varian accelerator. PACS number(s): 87.52.Ga, 87.52.Px, 87.53.Qc, 87.53.Wz PMID:12841794

High-speed technique based on a parallel projection correlation procedure for digital image correlation

NASA Astrophysics Data System (ADS)

Zaripov, D. I.; Renfu, Li

2018-05-01

The implementation of high-efficiency digital image correlation methods based on a zero-normalized cross-correlation (ZNCC) procedure for high-speed, time-resolved measurements using a high-resolution digital camera is associated with big data processing and is often time consuming. In order to speed-up ZNCC computation, a high-speed technique based on a parallel projection correlation procedure is proposed. The proposed technique involves the use of interrogation window projections instead of its two-dimensional field of luminous intensity. This simplification allows acceleration of ZNCC computation up to 28.8 times compared to ZNCC calculated directly, depending on the size of interrogation window and region of interest. The results of three synthetic test cases, such as a one-dimensional uniform flow, a linear shear flow and a turbulent boundary-layer flow, are discussed in terms of accuracy. In the latter case, the proposed technique is implemented together with an iterative window-deformation technique. On the basis of the results of the present work, the proposed technique is recommended to be used for initial velocity field calculation, with further correction using more accurate techniques.

Does technology acceleration equate to mask cost acceleration?

NASA Astrophysics Data System (ADS)

Trybula, Walter J.; Grenon, Brian J.

2003-06-01

The technology acceleration of the ITRS Roadmap has many implications on both the semiconductor sup-plier community and the manufacturers. INTERNATIONAL SEMATECH has revaluated the projected cost of advanced technology masks. Building on the methodology developed in 1996 for mask costs, this work provided a critical review of mask yields and factors relating to the manufacture of photolithography masks. The impact of the yields provided insight into the learning curve for leading edge mask manufac-turing. The projected mask set cost was surprising, and the ability to provide first and second year cost estimates provided additional information on technology introduction. From this information, the impact of technology acceleration can be added to the projected yields to evaluate the impact on mask costs.

Linking Project Evaluation and Goals-Based Teacher Evaluation: Evaluating the Accelerated Schools Project in South Carolina.

ERIC Educational Resources Information Center

Finnan, Christine; Davis, Sara Calhoun

This paper describes efforts to design an evaluation system that has as its primary objective helping schools effect positive change through the Accelerated Schools Project. Three characteristics were deemed essential: (1) that the evaluation be useful and meaningful; (2) that it be sensitive to local conditions; and (3) that evaluations of…

A new method for computing the reliability of consecutive k-out-of-n:F systems

NASA Astrophysics Data System (ADS)

Gökdere, Gökhan; Gürcan, Mehmet; Kılıç, Muhammet Burak

2016-01-01

In many physical systems, reliability evaluation, such as ones encountered in telecommunications, the design of integrated circuits, microwave relay stations, oil pipeline systems, vacuum systems in accelerators, computer ring networks, and spacecraft relay stations, have had applied consecutive k-out-of-n system models. These systems are characterized as logical connections among the components of the systems placed in lines or circles. In literature, a great deal of attention has been paid to the study of the reliability evaluation of consecutive k-out-of-n systems. In this paper, we propose a new method to compute the reliability of consecutive k-out-of-n:F systems, with n linearly and circularly arranged components. The proposed method provides a simple way for determining the system failure probability. Also, we write R-Project codes based on our proposed method to compute the reliability of the linear and circular systems which have a great number of components.

GPU computing with Kaczmarz’s and other iterative algorithms for linear systems

PubMed Central

Elble, Joseph M.; Sahinidis, Nikolaos V.; Vouzis, Panagiotis

2009-01-01

The graphics processing unit (GPU) is used to solve large linear systems derived from partial differential equations. The differential equations studied are strongly convection-dominated, of various sizes, and common to many fields, including computational fluid dynamics, heat transfer, and structural mechanics. The paper presents comparisons between GPU and CPU implementations of several well-known iterative methods, including Kaczmarz’s, Cimmino’s, component averaging, conjugate gradient normal residual (CGNR), symmetric successive overrelaxation-preconditioned conjugate gradient, and conjugate-gradient-accelerated component-averaged row projections (CARP-CG). Computations are preformed with dense as well as general banded systems. The results demonstrate that our GPU implementation outperforms CPU implementations of these algorithms, as well as previously studied parallel implementations on Linux clusters and shared memory systems. While the CGNR method had begun to fall out of favor for solving such problems, for the problems studied in this paper, the CGNR method implemented on the GPU performed better than the other methods, including a cluster implementation of the CARP-CG method. PMID:20526446

Non-linear effects in bunch compressor of TARLA

NASA Astrophysics Data System (ADS)

Yildiz, Hüseyin; Aksoy, Avni; Arikan, Pervin

2016-03-01

Transport of a beam through an accelerator beamline is affected by high order and non-linear effects such as space charge, coherent synchrotron radiation, wakefield, etc. These effects damage form of the beam, and they lead particle loss, emittance growth, bunch length variation, beam halo formation, etc. One of the known non-linear effects on low energy machine is space charge effect. In this study we focus on space charge effect for Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) machine which is designed to drive InfraRed Free Electron Laser covering the range of 3-250 µm. Moreover, we discuss second order effects on bunch compressor of TARLA.

ACCELERATION AND THE GIFTED.

ERIC Educational Resources Information Center

GIBSON, ARTHUR R.; STEPHANS, THOMAS M.

ACCELERATION OF PUPILS AND SUBJECTS IS CONSIDERED A MEANS OF EDUCATING THE ACADEMICALLY GIFTED STUDENT. FIVE INTRODUCTORY ARTICLES PROVIDE A FRAMEWORK FOR THINKING ABOUT ACCELERATION. FIVE PROJECT REPORTS OF ACCELERATED PROGRAMS IN OHIO ARE INCLUDED. ACCELERATION IS NOW BEING REGARDED MORE FAVORABLY THAN FORMERLY, BECAUSE METHODS HAVE BEEN…

Single-Event Effect Testing of the Linear Technology LTC6103HMS8#PBF Current Sense Amplifier

NASA Technical Reports Server (NTRS)

Yau, Ka-Yen; Campola, Michael J.; Wilcox, Edward

2016-01-01

The LTC6103HMS8#PBF (henceforth abbreviated as LTC6103) current sense amplifier from Linear Technology was tested for both destructive and non-destructive single-event effects (SEE) using the heavy-ion cyclotron accelerator beam at Lawrence Berkeley National Laboratory (LBNL) Berkeley Accelerator Effects (BASE) facility. During testing, the input voltages and output currents were monitored to detect single event latch-up (SEL) and single-event transients (SETs).

The CSU Accelerator and FEL Facility

NASA Astrophysics Data System (ADS)

Biedron, Sandra; Milton, Stephen; D'Audney, Alex; Edelen, Jonathan; Einstein, Josh; Harris, John; Hall, Chris; Horovitz, Kahren; Martinez, Jorge; Morin, Auralee; Sipahi, Nihan; Sipahi, Taylan; Williams, Joel

2014-03-01

The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test stand, and a magnetic test stand. The photocathode drive linac will be used in conjunction with a hybrid undulator capable of producing THz radiation. Details of the systems used in CSU Accelerator Facility are discussed.

Laser-Induced Linear-Field Particle Acceleration in Free Space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Liang Jie; Hong, Kyung -Han; Carbajo, Sergio

Linear-field particle acceleration in free space (which is distinct from geometries like the linac that requires components in the vicinity of the particle) has been studied for over 20 years, and its ability to eventually produce high-quality, high energy multi-particle bunches has remained a subject of great interest. Arguments can certainly be made that linear-field particle acceleration in free space is very doubtful given that first-order electron-photon interactions are forbidden in free space. Nevertheless, we chose to develop an accurate and truly predictive theoretical formalism to explore this remote possibility when intense, few-cycle electromagnetic pulses are used in a computationalmore » experiment. The formalism includes exact treatment of Maxwell’s equations and exact treatment of the interaction among the multiple individual particles at near and far field. Several surprising results emerge. We find that electrons interacting with intense laser pulses in free space are capable of gaining substantial amounts of energy that scale linearly with the feld amplitude. For example, 30keV electrons (2.5% energy spread) are accelerated to 61MeV (0.5% spread) and to 205MeV (0.25% spread) using 250 mJ and 2.5J lasers respectively. Furthermore, these findings carry important implications for our understanding of ultrafast electron-photon interactions in strong fields.« less

Laser-Induced Linear-Field Particle Acceleration in Free Space

DOE PAGES

Wong, Liang Jie; Hong, Kyung -Han; Carbajo, Sergio; ...

2017-09-11

Linear-field particle acceleration in free space (which is distinct from geometries like the linac that requires components in the vicinity of the particle) has been studied for over 20 years, and its ability to eventually produce high-quality, high energy multi-particle bunches has remained a subject of great interest. Arguments can certainly be made that linear-field particle acceleration in free space is very doubtful given that first-order electron-photon interactions are forbidden in free space. Nevertheless, we chose to develop an accurate and truly predictive theoretical formalism to explore this remote possibility when intense, few-cycle electromagnetic pulses are used in a computationalmore » experiment. The formalism includes exact treatment of Maxwell’s equations and exact treatment of the interaction among the multiple individual particles at near and far field. Several surprising results emerge. We find that electrons interacting with intense laser pulses in free space are capable of gaining substantial amounts of energy that scale linearly with the feld amplitude. For example, 30keV electrons (2.5% energy spread) are accelerated to 61MeV (0.5% spread) and to 205MeV (0.25% spread) using 250 mJ and 2.5J lasers respectively. Furthermore, these findings carry important implications for our understanding of ultrafast electron-photon interactions in strong fields.« less

Mechanisms of force production during linear accelerations in bluegill sunfish Lepomis macrochirus

NASA Astrophysics Data System (ADS)

Tytell, Eric D.; Wise, Tyler N.; Boden, Alexandra L.; Sanders, Erin K.; Schwalbe, Margot A. B.

2016-11-01

In nature, fish rarely swim steadily. Although unsteady behaviors are common, we know little about how fish change their swimming kinematics for routine accelerations, and how these changes affect the fluid dynamic forces and the wake produced. To study force production during acceleration, particle image velocimetry was used to quantify the wake of bluegill sunfish Lepomis macrochirus and to estimate the pressure field during linear accelerations and steady swimming. We separated "steady" and "unsteady" trials and quantified the forward acceleration using inertial measurement units. Compared to steady sequences, unsteady sequences had larger accelerations and higher body amplitudes. The wake consisted of single vortices shed during each tail movement (a '2S' wake). The structure did not change during acceleration, but the circulation of the vortices increased, resulting in larger forces. A fish swimming unsteadily produced significantly more force than the same fish swimming steadily, even when the accelerations were the same. This increase is likely due to increased added mass during unsteady swimming, as a result of the larger body amplitude. Pressure estimates suggest that the increase in force is correlated with more low pressure regions on the anterior body. This work was supported by ARO W911NF-14-1-0494 and NSF RCN-PLS 1062052.

Compact accelerator for medical therapy

DOEpatents

Caporaso, George J.; Chen, Yu-Jiuan; Hawkins, Steven A.; Sampayan, Stephen E.; Paul, Arthur C.

2010-05-04

A compact accelerator system having an integrated particle generator-linear accelerator with a compact, small-scale construction capable of producing an energetic (.about.70-250 MeV) proton beam or other nuclei and transporting the beam direction to a medical therapy patient without the need for bending magnets or other hardware often required for remote beam transport. The integrated particle generator-accelerator is actuable as a unitary body on a support structure to enable scanning of a particle beam by direction actuation of the particle generator-accelerator.

SLAC All Access: FACET

ScienceCinema

Hogan, Mark

2018-02-13

SLAC's Facility for Advanced Accelerator Experimental Tests, or FACET, is a test-bed where researchers are developing the technologies required for particle accelerators of the future. Scientists from all over the world come to explore ways of improving the power and efficiency of the particle accelerators used in basic research, medicine, industry and other areas important to society. In this video, Mark Hogan, head of SLAC's Advanced Accelerator Research Department, offers a glimpse into FACET, which uses part of SLAC's historic two-mile-long linear accelerator.

Accelerating Into the Future: From 0 to GeV in a Few Centimeters (LBNL Summer Lecture Series)

ScienceCinema

Leemans, Wim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Accelerator and Fusion Research Division (AFRD) and Laser Optics and Accelerator Systems Integrated Studies (LOASIS)

2018-05-04

Summer Lecture Series 2008: By exciting electric fields in plasma-based waveguides, lasers accelerate electrons in a fraction of the distance conventional accelerators require. The Accelerator and Fusion Research Division's LOASIS program, headed by Wim Leemans, has used 40-trillion-watt laser pulses to deliver billion-electron-volt (1 GeV) electron beams within centimeters. Leemans looks ahead to BELLA, 10-GeV accelerating modules that could power a future linear collider.

Accelerating Into the Future: From 0 to GeV in a Few Centimeters (LBNL Summer Lecture Series)

ScienceCinema

Leemans, Wim [LOASIS Program, AFRD

2017-12-09

July 8, 2008 Berkeley Lab lecture: By exciting electric fields in plasma-based waveguides, lasers accelerate electrons in a fraction of the distance conventional accelerators require. The Accelerator and Fusion Research Division's LOASIS program, headed by Wim Leemans, has used 40-trillion-watt laser pulses to deliver billion-electron-volt (1 GeV) electron beams within centimeters. Leemans looks ahead to BELLA, 10-GeV accelerating modules that could power a future linear collider.

Accelerated Electron-Beam Formation with a High Capture Coefficient in a Parallel Coupled Accelerating Structure

NASA Astrophysics Data System (ADS)

Chernousov, Yu. D.; Shebolaev, I. V.; Ikryanov, I. M.

2018-01-01

An electron beam with a high (close to 100%) coefficient of electron capture into the regime of acceleration has been obtained in a linear electron accelerator based on a parallel coupled slow-wave structure, electron gun with microwave-controlled injection current, and permanent-magnet beam-focusing system. The high capture coefficient was due to the properties of the accelerating structure, beam-focusing system, and electron-injection system. Main characteristics of the proposed systems are presented.

Acceleration and Velocity Sensing from Measured Strain

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi; Truax, Roger

2015-01-01

A simple approach for computing acceleration and velocity of a structure from the strain is proposed in this study. First, deflection and slope of the structure are computed from the strain using a two-step theory. Frequencies of the structure are computed from the time histories of strain using a parameter estimation technique together with an autoregressive moving average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. Simple harmonic motion is assumed for the acceleration computations, and the central difference equation with a linear autoregressive model is used for the computations of velocity. A cantilevered rectangular wing model is used to validate the simple approach. Quality of the computed deflection, acceleration, and velocity values are independent of the number of fibers. The central difference equation with a linear autoregressive model proposed in this study follows the target response with reasonable accuracy. Therefore, the handicap of the backward difference equation, phase shift, is successfully overcome.

A charged particle in a homogeneous magnetic field accelerated by a time-periodic Aharonov-Bohm flux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalvoda, T.; Stovicek, P., E-mail: stovicek@kmlinux.fjfi.cvut.cz

2011-10-15

We consider a nonrelativistic quantum charged particle moving on a plane under the influence of a uniform magnetic field and driven by a periodically time-dependent Aharonov-Bohm flux. We observe an acceleration effect in the case when the Aharonov-Bohm flux depends on time as a sinusoidal function whose frequency is in resonance with the cyclotron frequency. In particular, the energy of the particle increases linearly for large times. An explicit formula for the acceleration rate is derived with the aid of the quantum averaging method, and then it is checked against a numerical solution and a very good agreement is found.more » - Highlights: > A nonrelativistic quantum charged particle on a plane. > A homogeneous magnetic field and a periodically time-dependent Aharonov-Bohm flux. > The quantum averaging method applied to a time-dependent system. > A resonance of the AB flux with the cyclotron frequency. > An acceleration with linearly increasing energy; a formula for the acceleration rate.« less

Translational Vestibulo-Ocular Reflex and Motion Perception During Interaural Linear Acceleration: Comparison of Different Motion Paradigms

NASA Technical Reports Server (NTRS)

Beaton, K. H.; Holly, J. E.; Clement, G. R.; Wood, S. J.

2011-01-01

The neural mechanisms to resolve ambiguous tilt-translation motion have been hypothesized to be different for motion perception and eye movements. Previous studies have demonstrated differences in ocular and perceptual responses using a variety of motion paradigms, including Off-Vertical Axis Rotation (OVAR), Variable Radius Centrifugation (VRC), translation along a linear track, and tilt about an Earth-horizontal axis. While the linear acceleration across these motion paradigms is presumably equivalent, there are important differences in semicircular canal cues. The purpose of this study was to compare translation motion perception and horizontal slow phase velocity to quantify consistencies, or lack thereof, across four different motion paradigms. Twelve healthy subjects were exposed to sinusoidal interaural linear acceleration between 0.01 and 0.6 Hz at 1.7 m/s/s (equivalent to 10 tilt) using OVAR, VRC, roll tilt, and lateral translation. During each trial, subjects verbally reported the amount of perceived peak-to-peak lateral translation and indicated the direction of motion with a joystick. Binocular eye movements were recorded using video-oculography. In general, the gain of translation perception (ratio of reported linear displacement to equivalent linear stimulus displacement) increased with stimulus frequency, while the phase did not significantly vary. However, translation perception was more pronounced during both VRC and lateral translation involving actual translation, whereas perceptions were less consistent and more variable during OVAR and roll tilt which did not involve actual translation. For each motion paradigm, horizontal eye movements were negligible at low frequencies and showed phase lead relative to the linear stimulus. At higher frequencies, the gain of the eye movements increased and became more inphase with the acceleration stimulus. While these results are consistent with the hypothesis that the neural computational strategies for motion perception and eye movements differ, they also indicate that the specific motion platform employed can have a significant effect on both the amplitude and phase of each.

Sea-Level Acceleration Hotspot along the Atlantic Coast of North America

NASA Astrophysics Data System (ADS)

Sallenger, A. H.; Doran, K. J.; Howd, P.

2012-12-01

Spatial variations of sea level rise (SLR) can be forced by dynamic processes arising from circulation and variations in temperature and/or salinity, and by static equilibrium processes arising from mass re-distributions changing gravity and the earth's rotation and shape. The sea-level variations can form unique spatial patterns, yet there are very few field observations verifying predicted patterns, or fingerprints. We present evidence of SLR acceleration in a 1,000-km-long hotspot on the North American Atlantic coast north of Cape Hatteras, North Carolina to above Boston, Massachusetts. By using accelerations, or rate differences, sea level signals that are linear over sub-century records, like the relative sea level changes arising from vertical land movements of glacial isostatic adjustment, do not affect our results. For a 60-yr regression window (between 1950-1979 and 1980-2009), mean increase in the rate of SLR in the hotspot was 1.97 ± 0.64 mm/yr. (For a 40-yr window, the mean rate increase was 3.80 ± 1.06 mm/yr.) South of Cape Hatteras to Key West, Florida, rate differences for either 60 yr or 40 yr windows were not statistically different from zero (e.g. for 60 yr window: mean= 0.11 ± 0.92 mm/yr). This pattern is similar to a fingerprint of dynamic SLR established by sea-level projections in several climate model studies. Correlations were consistent with accelerated SLR associated with a slowdown of Atlantic Meridional Overturning Current.

Radiation Field Forming for Industrial Electron Accelerators Using Rare-Earth Magnetic Materials

NASA Astrophysics Data System (ADS)

Ermakov, A. N.; Khankin, V. V.; Shvedunov, N. V.; Shvedunov, V. I.; Yurov, D. S.

2016-09-01

The article describes the radiation field forming system for industrial electron accelerators, which would have uniform distribution of linear charge density at the surface of an item being irradiated perpendicular to the direction of its motion. Its main element is non-linear quadrupole lens made with the use of rare-earth magnetic materials. The proposed system has a number of advantages over traditional beam scanning systems that use electromagnets, including easier product irradiation planning, lower instantaneous local dose rate, smaller size, lower cost. Provided are the calculation results for a 10 MeV industrial electron accelerator, as well as measurement results for current distribution in the prototype build based on calculations.

Proposal for an astronaut mass measurement device for the Space Shuttle

NASA Technical Reports Server (NTRS)

Beyer, Neil; Lomme, Jon; Mccollough, Holly; Price, Bradford; Weber, Heidi

1994-01-01

For medical reasons, astronauts in space need to have their mass measured. Currently, this measurement is performed using a mass-spring system. The current system is large, inaccurate, and uncomfortable for the astronauts. NASA is looking for new, different, and preferably better ways to perform this measurement process. After careful analysis our design team decided on a linear acceleration process. Within the process, four possible concept variants are put forth. Among these four variants, one is suggested over the others. The variant suggested is that of a motor-winch system to linearly accelerate the astronaut. From acceleration and force measurements of the process combined Newton's second law, the mass of an astronaut can be calculated.

Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. IV. Responses after spectacle-induced adaptation

NASA Technical Reports Server (NTRS)

Clendaniel, R. A.; Lasker, D. M.; Minor, L. B.; Shelhamer, M. J. (Principal Investigator)

2001-01-01

The horizontal angular vestibuloocular reflex (VOR) evoked by sinusoidal rotations from 0.5 to 15 Hz and acceleration steps up to 3,000 degrees /s(2) to 150 degrees /s was studied in six squirrel monkeys following adaptation with x2.2 magnifying and x0.45 minimizing spectacles. For sinusoidal rotations with peak velocities of 20 degrees /s, there were significant changes in gain at all frequencies; however, the greatest gain changes occurred at the lower frequencies. The frequency- and velocity-dependent gain enhancement seen in normal monkeys was accentuated following adaptation to magnifying spectacles and diminished with adaptation to minimizing spectacles. A differential increase in gain for the steps of acceleration was noted after adaptation to the magnifying spectacles. The gain during the acceleration portion, G(A), of a step of acceleration (3,000 degrees /s(2) to 150 degrees /s) increased from preadaptation values of 1.05 +/- 0.08 to 1.96 +/- 0.16, while the gain during the velocity plateau, G(V), only increased from 0.93 +/- 0.04 to 1.36 +/- 0.08. Polynomial fits to the trajectory of the response during the acceleration step revealed a greater increase in the cubic than the linear term following adaptation with the magnifying lenses. Following adaptation to the minimizing lenses, the value of G(A) decreased to 0.61 +/- 0.08, and the value of G(V) decreased to 0.59 +/- 0.09 for the 3,000 degrees /s(2) steps of acceleration. Polynomial fits to the trajectory of the response during the acceleration step revealed that there was a significantly greater reduction in the cubic term than in the linear term following adaptation with the minimizing lenses. These findings indicate that there is greater modification of the nonlinear as compared with the linear component of the VOR with spectacle-induced adaptation. In addition, the latency to the onset of the adapted response varied with the dynamics of the stimulus. The findings were modeled with a bilateral model of the VOR containing linear and nonlinear pathways that describe the normal behavior and adaptive processes. Adaptation for the linear pathway is described by a transfer function that shows the dependence of adaptation on the frequency of the head movement. The adaptive process for the nonlinear pathway is a gain enhancement element that provides for the accentuated gain with rising head velocity and the increased cubic component of the responses to steps of acceleration. While this model is substantially different from earlier models of VOR adaptation, it accounts for the data in the present experiments and also predicts the findings observed in the earlier studies.

Using High-Powered Laser, Scientists Record Images of Chemical Interactions in RNA | Poster

Cancer.gov

A recent study at the Department of Energy’s Stanford Linear Accelerator Center National Accelerator Laboratory has literally shed new light on the structural interactions between RNA and another biomolecule.

Project acceleration : making the leap from pilot to commercialization.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borneo, Daniel R.

2010-05-01

Since the energy storage technology market is in a relatively emergent phase, narrowing the gap between pilot project status and commercialization is fundamental to the accelerating of this innovative market space. This session will explore regional market design factors to facilitate the storage enterprise. You will also hear about: quantifying transmission and generation efficiency enhancements; resource planning for storage; and assessing market mechanisms to accelerate storage adoption regionally.

SU-E-J-110: TG 51 Dosimetry : With Or Without Lead

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, M

TG-51 Dosimetry: With or Without Lead. Purpose: In this project, an analytical method has been introduced for adjustment of the TG-51 recommended KQ in order to produce accurate dosimetric data for high energy photons without the lead foil. Methods: These investigations were performed using a 30 cm × 30 cm × 30 cm CIVCO water tank, A12 EXRADIN Water proof Farmer Chamber, a Standard Imaging MAX 4000 electrometer, and 1 mm thick lead foil from Standard Imaging. Complete TG-51 was performed every month with and without lead. The results were analyzed and an analytical model has been developed for comparingmore » the values of KQ. TG-51 Table I was used to obtain KQ values. Results: The dosimetric evaluations were obtained for Varian Linear accelerators Model 21ix and 21ex. These results indicates that the measured data with lead foil in place as recommended by TG-51 is in excellent agreement (within 0.1%) with the calculated data obtained by the new model, from our dosimetry data without-lead. If equation 15 of the TG-51 report is used without any adjustments, it will lead to differences of about 1.6 % (on the average) in relative data which will Resultin differences of about 0.3 % (on the average) in the KQ Values. The KQ value for 18 MV obtained consistently with the equation of TG-51 “with lead” and “without lead” were 0.971 and 0.974, respectively. The 0.3 % higher results for KQ without lead eventually will lead to 0.3% larger output. However, by considering this model the KQ value was found to be 0.971 for dosimetry without lead. Conclusion: The analytical model that was introduced in this project was able to reproduce the dosimetric data of the high energy linear accelerators to within 0.1% without the use of the lead foil.« less

Extracting Time-Accurate Acceleration Vectors From Nontrivial Accelerometer Arrangements.

PubMed

Franck, Jennifer A; Blume, Janet; Crisco, Joseph J; Franck, Christian

2015-09-01

Sports-related concussions are of significant concern in many impact sports, and their detection relies on accurate measurements of the head kinematics during impact. Among the most prevalent recording technologies are videography, and more recently, the use of single-axis accelerometers mounted in a helmet, such as the HIT system. Successful extraction of the linear and angular impact accelerations depends on an accurate analysis methodology governed by the equations of motion. Current algorithms are able to estimate the magnitude of acceleration and hit location, but make assumptions about the hit orientation and are often limited in the position and/or orientation of the accelerometers. The newly formulated algorithm presented in this manuscript accurately extracts the full linear and rotational acceleration vectors from a broad arrangement of six single-axis accelerometers directly from the governing set of kinematic equations. The new formulation linearizes the nonlinear centripetal acceleration term with a finite-difference approximation and provides a fast and accurate solution for all six components of acceleration over long time periods (>250 ms). The approximation of the nonlinear centripetal acceleration term provides an accurate computation of the rotational velocity as a function of time and allows for reconstruction of a multiple-impact signal. Furthermore, the algorithm determines the impact location and orientation and can distinguish between glancing, high rotational velocity impacts, or direct impacts through the center of mass. Results are shown for ten simulated impact locations on a headform geometry computed with three different accelerometer configurations in varying degrees of signal noise. Since the algorithm does not require simplifications of the actual impacted geometry, the impact vector, or a specific arrangement of accelerometer orientations, it can be easily applied to many impact investigations in which accurate kinematics need to be extracted from single-axis accelerometer data.

MicroBooNE project team recognized by Department of Energy | News

Science.gov Websites

Financial Officer Finance Section Office of the Chief Operating Officer Facilities Engineering Services Accelerator Division Accelerator Physics Center Office of the Chief Safety Officer Environment, Safety, Health and Quality Section Office of the Chief Project Officer Office of Project Support Services Office of

Statistics of vacuum breakdown in the high-gradient and low-rate regime

NASA Astrophysics Data System (ADS)

Wuensch, Walter; Degiovanni, Alberto; Calatroni, Sergio; Korsbäck, Anders; Djurabekova, Flyura; Rajamäki, Robin; Giner-Navarro, Jorge

2017-01-01

In an increasing number of high-gradient linear accelerator applications, accelerating structures must operate with both high surface electric fields and low breakdown rates. Understanding the statistical properties of breakdown occurrence in such a regime is of practical importance for optimizing accelerator conditioning and operation algorithms, as well as of interest for efforts to understand the physical processes which underlie the breakdown phenomenon. Experimental data of breakdown has been collected in two distinct high-gradient experimental set-ups: A prototype linear accelerating structure operated in the Compact Linear Collider Xbox 12 GHz test stands, and a parallel plate electrode system operated with pulsed DC in the kV range. Collected data is presented, analyzed and compared. The two systems show similar, distinctive, two-part distributions of number of pulses between breakdowns, with each part corresponding to a specific, constant event rate. The correlation between distance and number of pulses between breakdown indicates that the two parts of the distribution, and their corresponding event rates, represent independent primary and induced follow-up breakdowns. The similarity of results from pulsed DC to 12 GHz rf indicates a similar vacuum arc triggering mechanism over the range of conditions covered by the experiments.

LIONs at the Stanford Linear Accelerator Center

DOE Office of Scientific and Technical Information (OSTI.GOV)

Constant, T.N.; Zdarko, R.W.; Simmons, R.H.

1998-01-01

The term LION is an acronym for Long Ionization Chamber. This is a distributed ion chamber which is used to monitor secondary ionization along the shield walls of a beam line resulting from incorrectly steered charged particle beams in lieu of the use of many discrete ion chambers. A cone of ionizing radiation emanating from a point source as a result of incorrect steering intercepts a portion of 1-5/8 inch Heliax cable (about 100 meters in length) filled with Argon gas at 20 psi and induces a pulsed current which is proportional to the ionizing charge. This signal is transmittedmore » via the cable to an integrator circuit whose output is directed to an electronic comparators, which in turn is used to turn off the accelerated primary beam when preset limits are exceeded. This device is used in the Stanford Linear Accelerator Center (SLAC) Beam Containment System (BCS) to prevent potentially hazardous ionizing radiation resulting from incorrectly steered beams in areas that might be occupied by people. This paper describes the design parameters and experience in use in the Final Focus Test Beam (FFTB) area of the Stanford Linear Accelerator Center.« less

The International Linear Collider Technical Design Report - Volume 3.II: Accelerator Baseline Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adolphsen, Chris

2013-06-26

The International Linear Collider Technical Design Report (TDR) describes in four volumes the physics case and the design of a 500 GeV centre-of-mass energy linear electron-positron collider based on superconducting radio-frequency technology using Niobium cavities as the accelerating structures. The accelerator can be extended to 1 TeV and also run as a Higgs factory at around 250 GeV and on the Z0 pole. A comprehensive value estimate of the accelerator is give, together with associated uncertainties. It is shown that no significant technical issues remain to be solved. Once a site is selected and the necessary site-dependent engineering is carriedmore » out, construction can begin immediately. The TDR also gives baseline documentation for two high-performance detectors that can share the ILC luminosity by being moved into and out of the beam line in a "push-pull" configuration. These detectors, ILD and SiD, are described in detail. They form the basis for a world-class experimental programme that promises to increase significantly our understanding of the fundamental processes that govern the evolution of the Universe.« less

The International Linear Collider Technical Design Report - Volume 3.I: Accelerator \\& in the Technical Design Phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adolphsen, Chris

2013-06-26

The International Linear Collider Technical Design Report (TDR) describes in four volumes the physics case and the design of a 500 GeV centre-of-mass energy linear electron-positron collider based on superconducting radio-frequency technology using Niobium cavities as the accelerating structures. The accelerator can be extended to 1 TeV and also run as a Higgs factory at around 250 GeV and on the Z0 pole. A comprehensive value estimate of the accelerator is give, together with associated uncertainties. It is shown that no significant technical issues remain to be solved. Once a site is selected and the necessary site-dependent engineering is carriedmore » out, construction can begin immediately. The TDR also gives baseline documentation for two high-performance detectors that can share the ILC luminosity by being moved into and out of the beam line in a "push-pull" configuration. These detectors, ILD and SiD, are described in detail. They form the basis for a world-class experimental programme that promises to increase significantly our understanding of the fundamental processes that govern the evolution of the Universe.« less

Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam

DOEpatents

Maschke, A.W.

1984-04-16

A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow through the assembly.

Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam

DOEpatents

Maschke, Alfred W.

1985-01-01

A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow throughout the assembly.

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure

DOE PAGES

Persaud, A.; Ji, Q.; Feinberg, E.; ...

2017-06-08

Here, a new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number ofmore » parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further red ucing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Finally, ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.« less

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure

NASA Astrophysics Data System (ADS)

Persaud, A.; Ji, Q.; Feinberg, E.; Seidl, P. A.; Waldron, W. L.; Schenkel, T.; Lal, A.; Vinayakumar, K. B.; Ardanuc, S.; Hammer, D. A.

2017-06-01

A new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number of parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further reducing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure.

PubMed

Persaud, A; Ji, Q; Feinberg, E; Seidl, P A; Waldron, W L; Schenkel, T; Lal, A; Vinayakumar, K B; Ardanuc, S; Hammer, D A

2017-06-01

A new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number of parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further reducing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.

Operations and maintenance manual for the linear accelerator (sled)

NASA Technical Reports Server (NTRS)

1981-01-01

The Linear Accelerator, a sliding chair which is pulled along a stationary platform in a horizontal axis is described. The driving force is a motor controlled by a velocity loop amplifier, and the mechanical link to the chair is a steel cable. The chair is moved in forward and reverse directions as indicated by the direction of motor rotation. The system operation is described with emphasis on the electronic control and monitoring functions. Line-by-line schematics and wire lists are included.

Non-linear acceleration at supernova remnant shocks and the hardening in the cosmic ray spectrum

NASA Astrophysics Data System (ADS)

Recchia, S.; Gabici, S.

2018-02-01

In the last few years, several experiments have shown that the cosmic ray spectrum below the knee is not a perfect power law. In particular, the proton and helium spectra show a spectral hardening by ˜0.1-0.2 in spectral index at particle energies of ˜ 200-300 GeV nucleon-1. Moreover, the helium spectrum is found to be harder than that of protons by ˜0.1 and some evidence for a similar hardening was also found in the spectra of heavier elements. Here, we consider the possibility that the hardening may be the result of a dispersion in the slope of the spectrum of cosmic rays accelerated at supernova remnant shocks. Such a dispersion is indeed expected within the framework of non-linear theories of diffusive shock acceleration, which predict steeper (harder) particle spectra for larger (smaller) cosmic ray acceleration efficiencies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edstrom Jr., D.; et al.

The low-energy section of the photoinjector-based electron linear accelerator at the Fermilab Accelerator Science & Technology (FAST) facility was recently commissioned to an energy of 50 MeV. This linear accelerator relies primarily upon pulsed SRF acceleration and an optional bunch compressor to produce a stable beam within a large operational regime in terms of bunch charge, total average charge, bunch length, and beam energy. Various instrumentation was used to characterize fundamental properties of the electron beam including the intensity, stability, emittance, and bunch length. While much of this instrumentation was commissioned in a 20 MeV running period prior, some (includingmore » a new Martin- Puplett interferometer) was in development or pending installation at that time. All instrumentation has since been recommissioned over the wide operational range of beam energies up to 50 MeV, intensities up to 4 nC/pulse, and bunch structures from ~1 ps to more than 50 ps in length.« less

Beam-based measurements of long-range transverse wakefields in the Compact Linear Collider main-linac accelerating structure

DOE PAGES

Zha, Hao; Latina, Andrea; Grudiev, Alexej; ...

2016-01-20

The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures for its main linacs. In order to maintain beam stability in multibunch operation, long-range transverse wakefields must be suppressed by 2 orders of magnitude between successive bunches, which are separated in time by 0.5 ns. Such strong wakefield suppression is achieved by equipping every accelerating structure cell with four damping waveguides terminated with individual rf loads. A beam-based experiment to directly measure the effectiveness of this long-range transverse wakefield and benchmark simulations was made in the FACET test facility at SLAC using a prototype CLIC accelerating structure. Furthermore,more » the experiment showed good agreement with the simulations and a strong suppression of the wakefields with an unprecedented minimum resolution of 0.1 V/(pC mm m).« less

SABRE, a 10-MV linear induction accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corely, J.P.; Alexander, J.A.; Pankuch, P.J.

SABRE (Sandia Accelerator and Beam Research Experiment) is a 10-MV, 250-kA, 40-ns linear induction accelerator. It was designed to be used in positive polarity output. Positive polarity accelerators are important for application to Sandia's ICF (Inertial Confinement Fusion) and LMF (Laboratory Microfusion Facility) program efforts. SABRE was built to allow a more detailed study of pulsed power issues associated with positive polarity output machines. MITL (Magnetically Insulated Transmission Line) voltage adder efficiency, extraction ion diode development, and ion beam transport and focusing. The SABRE design allows the system to operate in either positive polarity output for ion extraction applications ormore » negative polarity output for more conventional electron beam loads. Details of the design of SABRE and the results of initial machine performance in negative polarity operation are presented in this paper. 13 refs., 12 figs., 1 tab.« less

State of the art in electromagnetic modeling for the Compact Linear Collider

DOE Office of Scientific and Technical Information (OSTI.GOV)

Candel, Arno; Kabel, Andreas; Lee, Lie-Quan

SLAC's Advanced Computations Department (ACD) has developed the parallel 3D electromagnetic time-domain code T3P for simulations of wakefields and transients in complex accelerator structures. T3P is based on state-of-the-art Finite Element methods on unstructured grids and features unconditional stability, quadratic surface approximation and up to 6th-order vector basis functions for unprecedented simulation accuracy. Optimized for large-scale parallel processing on leadership supercomputing facilities, T3P allows simulations of realistic 3D structures with fast turn-around times, aiding the design of the next generation of accelerator facilities. Applications include simulations of the proposed two-beam accelerator structures for the Compact Linear Collider (CLIC) - wakefieldmore » damping in the Power Extraction and Transfer Structure (PETS) and power transfer to the main beam accelerating structures are investigated.« less

Reduction of beam corkscrew motion on the ETAII linear induction accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turner, W.C.; Allen, S.L.; Brand, H.R.

1990-09-04

The ETAII linear induction accelerator (6MeV, 3kA, 70ns) is designed to drive a microwave free electron laser (FEL) and demonstrate the front end accelerator technology for a shorter wavelength FEL. Performance to date has been limited by beam corkscrew motion that is driven by energy sweep and misalignment of the solenoidal focusing magnets. Modifications to the pulse power distribution system and magnetic alignment are expected to reduce the radius of corkscrew motion from its present value of 1 cm to less than 1 mm. The modifications have so far been carried out on the first 2.7 MeV (injector plus 20more » accelerator cells) and experiments are beginning. In this paper we will present calculations of central flux line alignment, beam corkscrew motion and beam brightness that are anticipated with the modified ETAII. 10 refs., 4 figs., 1 tab.« less

Construction and comparison of Louisiana's conventional and alternative base courses under accelerated loading

DOT National Transportation Integrated Search

1998-08-01

The report describes the first testing series, Phase, of the first project, Experiment 1, with the Louisiana Transportation Research Center Accelerated Loading Facility. The background to the project is described and details of the trial pavements si...

SU-F-T-313: Clinical Results of a New Customer Acceptance Test for Elekta VMAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rusk, B; Fontenot, J

Purpose: To report the results of a customer acceptance test (CAT) for VMAT treatments for two matched Elekta linear accelerators. Methods: The CAT tests were performed on two clinically matched Elekta linear accelerators equipped with a 160-leaf MLC. Functional tests included performance checks of the control system during dynamic movements of the diaphragms, MLC, and gantry. Dosimetric tests included MLC picket fence tests at static and variable dose rates and a diaphragm alignment test, all performed using the on-board EPID. Additionally, beam symmetry during arc delivery was measured at the four cardinal angles for high and low dose rate modesmore » using a 2D detector array. Results of the dosimetric tests were analyzed using the VMAT CAT analysis tool. Results: Linear accelerator 1 (LN1) met all stated CAT tolerances. Linear accelerator 2 (LN2) passed the geometric, beam symmetry, and MLC position error tests but failed the relative dose average test for the diaphragm abutment and all three picket fence fields. Though peak doses in the abutment regions were consistent, the average dose was below the stated tolerance corresponding to a leaf junction that was too narrow. Despite this, no significant differences in patient specific VMAT quality assurance measured were observed between the accelerators and both passed monthly MLC quality assurance performed with the Hancock test. Conclusion: Results from the CAT showed LN2 with relative dose averages in the abutment regions of the diaphragm and MLC tests outside the tolerances resulting from differences in leaf gap distances. Tolerances of the dose average tests from the CAT may be small enough to detect MLC errors which do not significantly affect patient QA or the routine MLC tests.« less

Activation of Dosimeters Used in qa of Medical Linear Accelerators

NASA Astrophysics Data System (ADS)

Polaczek-Grelik, Kinga; Nowacka, Magdalena; Raczkowski, Maciej

2017-09-01

This paper presents the first results of a project intended to investigate γ-radiation activity induced in dosimeters used in clinical practice during routine quality assurance of high-energy photon beams emitted by electron linear accelerators. Two aspects of the activation via photonuclear reactions (X, n) of therapeutic beam and subsequent capture of secondary neutrons (n,γ) are under considerations: the influence of activation on intrinsic background of the dosimeters and exposure of dosimetrists who operate this equipment. The activation of several types of ionization chambers as well as the silicon diodes was studied after long-time exposure (10 000 MUs) of the 15 MV photon beam (Elekta Synergy). Photon fluxes obtained from spectra of γ-rays registered by HPGe spectrometer were subsequently converted to equivalent doses using appropriate coefficients. The main contribution to the induced activity comes from the neutron capture process on Al, Mn and Cu, therefore it decays quite fast with the half-lives of the order of 15 minutes. Nevertheless, the activation of chlorine was also observed. The estimated equivalent doses to skin and eye lens were in the range 0.19 - 0.62 μSv/min. However, no influence on intrinsic background signal of all studied dosimeters was observed. The preliminary results indicate that induced radioactivity of dosimeters is strongly influenced by therapeutic beam quality and neutron source strength of particular linac. This dependence will be studied deeper in order to quantify it more precisely.

New concept on an integrated interior magnetic resonance imaging and medical linear accelerator system for radiation therapy

PubMed Central

Jia, Xun; Tian, Zhen; Xi, Yan; Jiang, Steve B.; Wang, Ge

2017-01-01

Abstract. Image guidance plays a critical role in radiotherapy. Currently, cone-beam computed tomography (CBCT) is routinely used in clinics for this purpose. While this modality can provide an attenuation image for therapeutic planning, low soft-tissue contrast affects the delineation of anatomical and pathological features. Efforts have recently been devoted to several MRI linear accelerator (LINAC) projects that lead to the successful combination of a full diagnostic MRI scanner with a radiotherapy machine. We present a new concept for the development of the MRI-LINAC system. Instead of combining a full MRI scanner with the LINAC platform, we propose using an interior MRI (iMRI) approach to image a specific region of interest (RoI) containing the radiation treatment target. While the conventional CBCT component still delivers a global image of the patient’s anatomy, the iMRI offers local imaging of high soft-tissue contrast for tumor delineation. We describe a top-level system design for the integration of an iMRI component into an existing LINAC platform. We performed numerical analyses of the magnetic field for the iMRI to show potentially acceptable field properties in a spherical RoI with a diameter of 15 cm. This field could be shielded to a sufficiently low level around the LINAC region to avoid electromagnetic interference. Furthermore, we investigate the dosimetric impacts of this integration on the radiotherapy beam. PMID:28331888

Research on evaluating water resource resilience based on projection pursuit classification model

NASA Astrophysics Data System (ADS)

Liu, Dong; Zhao, Dan; Liang, Xu; Wu, Qiuchen

2016-03-01

Water is a fundamental natural resource while agriculture water guarantees the grain output, which shows that the utilization and management of water resource have a significant practical meaning. Regional agricultural water resource system features with unpredictable, self-organization, and non-linear which lays a certain difficulty on the evaluation of regional agriculture water resource resilience. The current research on water resource resilience remains to focus on qualitative analysis and the quantitative analysis is still in the primary stage, thus, according to the above issues, projection pursuit classification model is brought forward. With the help of artificial fish-swarm algorithm (AFSA), it optimizes the projection index function, seeks for the optimal projection direction, and improves AFSA with the application of self-adaptive artificial fish step and crowding factor. Taking Hongxinglong Administration of Heilongjiang as the research base and on the basis of improving AFSA, it established the evaluation of projection pursuit classification model to agriculture water resource system resilience besides the proceeding analysis of projection pursuit classification model on accelerating genetic algorithm. The research shows that the water resource resilience of Hongxinglong is the best than Raohe Farm, and the last 597 Farm. And the further analysis shows that the key driving factors influencing agricultural water resource resilience are precipitation and agriculture water consumption. The research result reveals the restoring situation of the local water resource system, providing foundation for agriculture water resource management.

Method of Calibrating a Force Balance

NASA Technical Reports Server (NTRS)

Parker, Peter A. (Inventor); Rhew, Ray D. (Inventor); Johnson, Thomas H. (Inventor); Landman, Drew (Inventor)

2015-01-01

A calibration system and method utilizes acceleration of a mass to generate a force on the mass. An expected value of the force is calculated based on the magnitude and acceleration of the mass. A fixture is utilized to mount the mass to a force balance, and the force balance is calibrated to provide a reading consistent with the expected force determined for a given acceleration. The acceleration can be varied to provide different expected forces, and the force balance can be calibrated for different applied forces. The acceleration may result from linear acceleration of the mass or rotational movement of the mass.

Joseph Rotblat: influences, scientific achievements and legacy

NASA Astrophysics Data System (ADS)

Underwood, Martin

2008-11-01

Joseph Rotblat was one of the most distinguished nuclear physicists and peace campaigners of the post Second World War period. His peace activities rank alongside those of Albert Einstein and Bertrand Russell; he won the Nobel Peace Prize, jointly with the Pugwash movement, that he helped found. However, he made significant contributions to science, and in particular to the medical applications of accelerators, radiation and radio-nuclides. In this article his early work and influences in Poland are described. He then joined James Chadwick at Liverpool University and began work on the cyclotron recently constructed there. Rotblat then, together with Chadwick, joined the Manhattan Project. This experience was to shape his life. He stayed at Los Alamos for less than a year before walking out. He was suspected of being a spy. Rotblat then became Professor of Physics at St Bartholomew's Medical College and pioneered the use of a 15 MeV linear accelerator in treatment and research. He made fundamental contributions to understanding the effects of the fallout from nuclear bomb tests. He also, together with Patricia Lindop, made important contributions to understanding the biological effects of radiation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swapan Chattopadhyay

Hurricane Isabel was at category five--the most violent on the Saffir-Simpson scale of hurricane strength--when it began threatening the central Atlantic seaboard of the US. Over the course of several days, precautions against the extreme weather conditions were taken across the Jefferson Lab site in south-east Virginia. On 18 September 2003, when Isabel struck North Carolina's Outer Banks and moved northward, directly across the region around the laboratory, the storm was still quite destructive, albeit considerably reduced in strength. The flood surge and trees felled by wind substantially damaged or even devastated buildings and homes, including many belonging to Jeffersonmore » Lab staff members. For the laboratory itself, Isabel delivered an unplanned and severe challenge in another form: a power outage that lasted nearly three-and-a-half days, and which severely tested the robustness of Jefferson Lab's two superconducting machines, the Continuous Electron Beam Accelerator Facility (CEBAF) and the superconducting radiofrequency ''driver'' accelerator of the laboratory's free-electron laser. Robustness matters greatly for science at a time when microwave superconducting linear accelerators (linacs) are not only being considered, but in some cases already being built for projects such as neutron sources, rare-isotope accelerators, innovative light sources and TeV-scale electron-positron linear colliders. Hurricane Isabel interrupted a several-week-long maintenance shutdown of CEBAF, which serves nuclear and particle physics and represents the world's pioneering large-scale implementation of superconducting radiofrequency (SRF) technology. The racetrack-shaped machine is actually a pair of 500-600 MeV SRF linacs interconnected by recirculation arc beamlines. CEBAF delivers simultaneous beams at up to 6 GeV to three experimental halls. An imminent upgrade will double the energy to 12 GeV and add an extra hall for ''quark confinement'' studies. On a smaller scale, Jefferson Lab's original kilowatt-scale infrared free-electron laser (FEL) is ''driven'' by a high-current cousin of CEBAF, a 70 MeV SRF linac with a high-current injector. The FEL serves multidisciplinary science and technology as the world's highest-average-power source of tunable coherent infrared light. An upgrade to 10 kW is in commissioning--as it was when Isabel began threatening.« less

Multiple solution of linear algebraic systems by an iterative method with recomputed preconditioner in the analysis of microstrip structures

NASA Astrophysics Data System (ADS)

Ahunov, Roman R.; Kuksenko, Sergey P.; Gazizov, Talgat R.

2016-06-01

A multiple solution of linear algebraic systems with dense matrix by iterative methods is considered. To accelerate the process, the recomputing of the preconditioning matrix is used. A priory condition of the recomputing based on change of the arithmetic mean of the current solution time during the multiple solution is proposed. To confirm the effectiveness of the proposed approach, the numerical experiments using iterative methods BiCGStab and CGS for four different sets of matrices on two examples of microstrip structures are carried out. For solution of 100 linear systems the acceleration up to 1.6 times, compared to the approach without recomputing, is obtained.

Non-linear effects in bunch compressor of TARLA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yildiz, Hüseyin, E-mail: huseyinyildiz006@gmail.com, E-mail: huseyinyildiz@gazi.edu.tr; Aksoy, Avni; Arikan, Pervin

2016-03-25

Transport of a beam through an accelerator beamline is affected by high order and non-linear effects such as space charge, coherent synchrotron radiation, wakefield, etc. These effects damage form of the beam, and they lead particle loss, emittance growth, bunch length variation, beam halo formation, etc. One of the known non-linear effects on low energy machine is space charge effect. In this study we focus on space charge effect for Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) machine which is designed to drive InfraRed Free Electron Laser covering the range of 3-250 µm. Moreover, we discuss second order effects onmore » bunch compressor of TARLA.« less

High-frequency ground motion amplification during the 2011 Tohoku earthquake explained by soil dilatancy

NASA Astrophysics Data System (ADS)

Roten, D.; Fäh, D.; Bonilla, L. F.

2013-05-01

Ground motions of the 2011 Tohoku earthquake recorded at Onahama port (Iwaki, Fukushima prefecture) rank among the highest accelerations ever observed, with the peak amplitude of the 3-D acceleration vector approaching 2g. The response of the site was distinctively non-linear, as indicated by the presence of horizontal acceleration spikes which have been linked to cyclic mobility during similar observations. Compared to records of weak ground motions, the response of the site during the Mw 9.1 earthquake was characterized by increased amplification at frequencies above 10 Hz and in peak ground acceleration. This behaviour contrasts with the more common non-linear response encountered at non-liquefiable sites, which results in deamplification at higher frequencies. We simulate propagation of SH waves through the dense sand deposit using a non-linear finite difference code that is capable of modelling the development of excess pore water pressure. Dynamic soil parameters are calibrated using a direct search method that minimizes the difference between observed and simulated acceleration envelopes and response spectra. The finite difference simulations yield surface acceleration time-series that are consistent with the observations in shape and amplitude, pointing towards soil dilatancy as a likely explanation for the high-frequency pulses recorded at Onahama port. The simulations also suggest that the occurrence of high-frequency spikes coincided with a rapid increase in pore water pressure in the upper part of the sand deposit between 145 and 170 s. This sudden increase is possibly linked to a burst of high-frequency energy from a large slip patch below the Iwaki region.

Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

DOEpatents

Caporaso, G.J.; Sampayan, S.E.; Kirbie, H.C.

1998-10-13

A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface. 12 figs.

Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

DOEpatents

Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

1998-01-01

A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

On isocentre adjustment and quality control in linear accelerator based radiosurgery with circular collimators and room lasers.

PubMed

Treuer, H; Hoevels, M; Luyken, K; Gierich, A; Kocher, M; Müller, R P; Sturm, V

2000-08-01

We have developed a densitometric method for measuring the isocentric accuracy and the accuracy of marking the isocentre position for linear accelerator based radiosurgery with circular collimators and room lasers. Isocentric shots are used to determine the accuracy of marking the isocentre position with room lasers and star shots are used to determine the wobble of the gantry and table rotation movement, the effect of gantry sag, the stereotactic collimator alignment, and the minimal distance between gantry and table rotation axes. Since the method is based on densitometric measurements, beam spot stability is implicitly tested. The method developed is also suitable for quality assurance and has proved to be useful in optimizing isocentric accuracy. The method is simple to perform and only requires a film box and film scanner for instrumentation. Thus, the method has the potential to become widely available and may therefore be useful in standardizing the description of linear accelerator based radiosurgical systems.

Radiosurgery with a linear accelerator. Methodological aspects.

PubMed

Betti, O O; Galmarini, D; Derechinsky, V

1991-01-01

Based on the concepts of Leksell and on recommendations of different Swedish physicists on the use of linear accelerator for radiosurgical use, we developed a new methodology coupling the Talairach stereotactic system with a commercial linac. Anatomical facts encouraged us to use coronal angles of irradiation employing the angular displacement of the linac above the horizontal plane. Different coronal planes are obtained by rotation of the stereotactic frame. The center of the irradiated target coincides with the irradiation and rotation center of the linear accelerator. Multiple targets can be irradiated in the same session. We use as recommended a secondary collimator in heavy alloy. Special software was prepared after different dosimetric controls. The use of a PC allows us to employ 1-6 targets and different collimators to displace the isocenters in order to obtain geometrical isodose modification, and to change the value of each irradiation arc or portions of each arc in some minutes. Simple or sophisticated neurosurgical strategies can be applied in the treatment of frequently irregular shape and volume AVMs.

Alignment of the Stanford Linear Collider Arcs: Concepts and results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pitthan, R.; Bell, B.; Friedsam, H.

1987-02-01

The alignment of the Arcs for the Stanford Linear Collider at SLAC has posed problems in accelerator survey and alignment not encountered before. These problems come less from the tight tolerances of 0.1 mm, although reaching such a tight statistically defined accuracy in a controlled manner is difficult enough, but from the absence of a common reference plane for the Arcs. Traditional circular accelerators, including HERA and LEP, have been designed in one plane referenced to local gravity. For the SLC Arcs no such single plane exists. Methods and concepts developed to solve these and other problems, connected with themore » unique design of SLC, range from the first use of satellites for accelerator alignment, use of electronic laser theodolites for placement of components, computer control of the manual adjustment process, complete automation of the data flow incorporating the most advanced concepts of geodesy, strict separation of survey and alignment, to linear principal component analysis for the final statistical smoothing of the mechanical components.« less

Overview of graduate training program of John Adams Institute for Accelerator Science

NASA Astrophysics Data System (ADS)

Seryi, Andrei

The John Adams Institute for Accelerator Science is a center of excellence in the UK for advanced and novel accelerator technology, providing expertise, research, development and training in accelerator techniques, and promoting advanced accelerator applications in science and society. We work in JAI on design of novel light sources upgrades of 3-rd generation and novel FELs, on plasma acceleration and its application to industrial and medical fields, on novel energy recovery compact linacs and advanced beam diagnostics, and many other projects. The JAI is based on three universities - University of Oxford, Imperial College London and Royal Holloway University of London. Every year 6 to 10 accelerators science experts, trained via research on cutting edge projects, defend their PhD thesis in JAI partner universities. In this presentation we will overview the research and in particular the highly successful graduate training program in JAI.

Studies on Muon Induction Acceleration and an Objective Lens Design for Transmission Muon Microscope

NASA Astrophysics Data System (ADS)

Artikova, Sayyora; Yoshida, Mitsuhiro; Naito, Fujio

Muon acceleration will be accomplished by a set of induction cells, where each increases the energy of the muon beam by an increment of up to 30 kV. The cells are arranged in a linear way resulting in total accelerating voltage of 300 kV. Acceleration time in the linac is about hundred nanoseconds. Induction field calculation is based on an electrostatic approximation. Beam dynamics in the induction accelerator is investigated and final beam focusing on specimen is realized by designing a pole piece lens.

Design of general apochromatic drift-quadrupole beam lines

NASA Astrophysics Data System (ADS)

Lindstrøm, C. A.; Adli, E.

2016-07-01

Chromatic errors are normally corrected using sextupoles in regions of large dispersion. In low emittance linear accelerators, use of sextupoles can be challenging. Apochromatic focusing is a lesser-known alternative approach, whereby chromatic errors of Twiss parameters are corrected without the use of sextupoles, and has consequently been subject to renewed interest in advanced linear accelerator research. Proof of principle designs were first established by Montague and Ruggiero and developed more recently by Balandin et al. We describe a general method for designing drift-quadrupole beam lines of arbitrary order in apochromatic correction, including analytic expressions for emittance growth and other merit functions. Worked examples are shown for plasma wakefield accelerator staging optics and for a simple final focus system.

Short-range wakefields generated in the blowout regime of plasma-wakefield acceleration

NASA Astrophysics Data System (ADS)

Stupakov, G.

2018-04-01

In the past, calculation of wakefields generated by an electron bunch propagating in a plasma has been carried out in linear approximation, where the plasma perturbation can be assumed small and plasma equations of motion linearized. This approximation breaks down in the blowout regime where a high-density electron driver expels plasma electrons from its path and creates a cavity void of electrons in its wake. In this paper, we develop a technique that allows us to calculate short-range longitudinal and transverse wakes generated by a witness bunch being accelerated inside the cavity. Our results can be used for studies of the beam loading and the hosing instability of the witness bunch in plasma-wakefield and laser-wakefield acceleration.

Governance of the International Linear Collider Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foster, B.; /Oxford U.; Barish, B.

Governance models for the International Linear Collider Project are examined in the light of experience from similar international projects around the world. Recommendations for one path which could be followed to realize the ILC successfully are outlined. The International Linear Collider (ILC) is a unique endeavour in particle physics; fully international from the outset, it has no 'host laboratory' to provide infrastructure and support. The realization of this project therefore presents unique challenges, in scientific, technical and political arenas. This document outlines the main questions that need to be answered if the ILC is to become a reality. It describesmore » the methodology used to harness the wisdom displayed and lessons learned from current and previous large international projects. From this basis, it suggests both general principles and outlines a specific model to realize the ILC. It recognizes that there is no unique model for such a laboratory and that there are often several solutions to a particular problem. Nevertheless it proposes concrete solutions that the authors believe are currently the best choices in order to stimulate discussion and catalyze proposals as to how to bring the ILC project to fruition. The ILC Laboratory would be set up by international treaty and be governed by a strong Council to whom a Director General and an associated Directorate would report. Council would empower the Director General to give strong management to the project. It would take its decisions in a timely manner, giving appropriate weight to the financial contributions of the member states. The ILC Laboratory would be set up for a fixed term, capable of extension by agreement of all the partners. The construction of the machine would be based on a Work Breakdown Structure and value engineering and would have a common cash fund sufficiently large to allow the management flexibility to optimize the project's construction. Appropriate contingency, clearly apportioned at both a national and global level, is essential if the project is to be realised. Finally, models for running costs and decommissioning at the conclusion of the ILC project are proposed. This document represents an interim report of the bodies and individuals studying these questions inside the structure set up and supervised by the International Committee for Future Accelerators (ICFA). It represents a request for comment to the international community in all relevant disciplines, scientific, technical and most importantly, political. Many areas require further study and some, in particular the site selection process, have not yet progressed sufficiently to be addressed in detail in this document. Discussion raised by this document will be vital in framing the final proposals due to be published in 2012 in the Technical Design Report being prepared by the Global Design Effort of the ILC.« less

USLCSG Task Force

Science.gov Websites

Unites States Linear Collider Steering Group dot dot dot dot What's New! June 2003 Meeting Welcome to the USLCSG Task Force at the Stanford Linear Accelerator Center [Enter] dot dot SLAC Page Owners

Creation of high-energy electron tails by means of the modified two-stream instability

NASA Technical Reports Server (NTRS)

Tanaka, M.; Papadopoulos, K.

1983-01-01

Particle simulations of the modified two-stream instability demonstrate strong electron acceleration rather than bulk heating when the relative drift speed is below a critical speed Vc. A very interesting nonlinear mode transition and autoresonance acceleration process is observed which accelerates the electrons much above the phase speed of the linearly unstable modes. Simple criteria are presented that predict the value of Vc and the number density of the accelerated electrons.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahl, P.F.

This year, 1992, marks the 65th anniversary of the publication of Rolf Wideroe`s doctoral dissertation. In it, he described not only the operating principles of the betatron, but also a working model of the first linear accelerator, constructed according to his own design. The latter, a resonance accelerator, gave Ernest Lawrence the idea for his cyclotron. Since Wideroe and his accelerator initiatives may not be very familiar to today`s accelerator physicists, the following is a brief recapitulation of the man and his work.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahl, P.F.

This year, 1992, marks the 65th anniversary of the publication of Rolf Wideroe's doctoral dissertation. In it, he described not only the operating principles of the betatron, but also a working model of the first linear accelerator, constructed according to his own design. The latter, a resonance accelerator, gave Ernest Lawrence the idea for his cyclotron. Since Wideroe and his accelerator initiatives may not be very familiar to today's accelerator physicists, the following is a brief recapitulation of the man and his work.

Relating Time-Dependent Acceleration and Height Using an Elevator

ERIC Educational Resources Information Center

Kinser, Jason M.

2015-01-01

A simple experiment in relating a time-dependent linear acceleration function to height is explored through the use of a smartphone and an elevator. Given acceleration as a function of time, a(t), the velocity function and position functions are determined through integration as in v(t)=? a(t) dt (1) and x(t)=? v(t) dt. Mobile devices such as…

Minimum time acceleration of aircraft turbofan engines by using an algorithm based on nonlinear programming

NASA Technical Reports Server (NTRS)

Teren, F.

1977-01-01

Minimum time accelerations of aircraft turbofan engines are presented. The calculation of these accelerations was made by using a piecewise linear engine model, and an algorithm based on nonlinear programming. Use of this model and algorithm allows such trajectories to be readily calculated on a digital computer with a minimal expenditure of computer time.

Acceleration and torque feedback for robotic control - Experimental results

NASA Technical Reports Server (NTRS)

Mclnroy, John E.; Saridis, George N.

1990-01-01

Gross motion control of robotic manipulators typically requires significant on-line computations to compensate for nonlinear dynamics due to gravity, Coriolis, centripetal, and friction nonlinearities. One controller proposed by Luo and Saridis avoids these computations by feeding back joint acceleration and torque. This study implements the controller on a Puma 600 robotic manipulator. Joint acceleration measurement is obtained by measuring linear accelerations of each joint, and deriving a computationally efficient transformation from the linear measurements to the angular accelerations. Torque feedback is obtained by using the previous torque sent to the joints. The implementation has stability problems on the Puma 600 due to the extremely high gains inherent in the feedback structure. Since these high gains excite frequency modes in the Puma 600, the algorithm is modified to decrease the gain inherent in the feedback structure. The resulting compensator is stable and insensitive to high frequency unmodeled dynamics. Moreover, a second compensator is proposed which uses acceleration and torque feedback, but still allows nonlinear terms to be fed forward. Thus, by feeding the increment in the easily calculated gravity terms forward, improved responses are obtained. Both proposed compensators are implemented, and the real time results are compared to those obtained with the computed torque algorithm.

Source-to-accelerator quadrupole matching section for a compact linear accelerator

NASA Astrophysics Data System (ADS)

Seidl, P. A.; Persaud, A.; Ghiorso, W.; Ji, Q.; Waldron, W. L.; Lal, A.; Vinayakumar, K. B.; Schenkel, T.

2018-05-01

Recently, we presented a new approach for a compact radio-frequency (RF) accelerator structure and demonstrated the functionality of the individual components: acceleration units and focusing elements. In this paper, we combine these units to form a working accelerator structure: a matching section between the ion source extraction grids and the RF-acceleration unit and electrostatic focusing quadrupoles between successive acceleration units. The matching section consists of six electrostatic quadrupoles (ESQs) fabricated using 3D-printing techniques. The matching section enables us to capture more beam current and to match the beam envelope to conditions for stable transport in an acceleration lattice. We present data from an integrated accelerator consisting of the source, matching section, and an ESQ doublet sandwiched between two RF-acceleration units.

CARE activities on superconducting RF cavities at INFN Milano

NASA Astrophysics Data System (ADS)

Bosotti, A.; Pierini, P.; Michelato, P.; Pagani, C.; Paparella, R.; Panzeri, N.; Monaco, L.; Paulon, R.; Novati, M.

2005-09-01

The SC RF group at INFN Milano-LASA is involved both in the TESLA/TTF collaboration and in the research and design activity on superconducting cavities for proton accelerators. Among these activities, some are supported by the European community within the CARE project. In the framework of the JRASRF collaboration we are developing a coaxial blade tuner for ILC (International Linear Collider) cavities, integrated with piezoelectric actuators for the compensation of the Lorenz force detuning and microphonics perturbation. Another activity, regarding the improved component design on SC technology, based on the information retrieving about the status of art on ancillaries and experience of various laboratories involved in SCRF, has started in our laboratory. Finally, in the framework of the HIPPI collaboration, we are testing two low beta superconducting cavities, built for the Italian TRASCO project, to verify the possibility to use them for pulsed operation. All these activities will be described here, together with the main results and the future perspectives.

High power microwave source development

NASA Astrophysics Data System (ADS)

Benford, James N.; Miller, Gabriel; Potter, Seth; Ashby, Steve; Smith, Richard R.

1995-05-01

The requirements of this project have been to: (1) improve and expand the sources available in the facility for testing purposes and (2) perform specific tasks under direction of the Defense Nuclear Agency about the applications of high power microwaves (HPM). In this project the HPM application was power beaming. The requirements of this program were met in the following way: (1) We demonstrated that a compact linear induction accelerator can drive HPM sources at repetition rates in excess of 100 HZ at peak microwave powers of a GW. This was done for the relativistic magnetron. Since the conclusion of this contract such specifications have also been demonstrated for the relativistic klystron under Ballistic Missile Defense Organization funding. (2) We demonstrated an L band relativistic magnetron. This device has been used both on our single pulse machines, CAMEL and CAMEL X, and the repetitive system CLIA. (3) We demonstrated that phase locking of sources together in large numbers is a feasible technology and showed the generation of multigigawatt S-band radiation in an array of relativistic magnetrons.

Human centromere genomics: now it's personal.

PubMed

Hayden, Karen E

2012-07-01

Advances in human genomics have accelerated studies in evolution, disease, and cellular regulation. However, centromere sequences, defining the chromosomal interface with spindle microtubules, remain largely absent from ongoing genomic studies and disconnected from functional, genome-wide analyses. This disparity results from the challenge of predicting the linear order of multi-megabase-sized regions that are composed almost entirely of near-identical satellite DNA. Acknowledging these challenges, the field of human centromere genomics possesses the potential to rapidly advance given the availability of individual, or personalized, genome projects matched with the promise of long-read sequencing technologies. Here I review the current genomic model of human centromeres in consideration of those studies involving functional datasets that examine the role of sequence in centromere identity.

Technical reference for the use of the slow crack growth test for modeling and predicting the long-term performance of polyethylene gas pipes. Final report, March 1987-May 1992. Volume 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanninen, M.F.; O'Donoghue, P.E.; Popelar, C.F.

1993-02-01

The project was undertaken for the purposes of quantifying the Battelle slow crack growth (SCG) test for predicting long-term performance of polyethylene gas distribution pipes, and of demonstrating the applicability of the methodology for use by the gas industry for accelerated characterization testing, thereby bringing the SCG test development effort to a closure. The work has revealed that the Battelle SCG test, and the linear fracture mechanics interpretation that it currently utilizes, is valid for a class of PE materials. The long-term performance of these materials in various operating conditions can therefore be effectively predicted.

Development of high intensity linear accelerator for heavy ion inertial fusion driver

NASA Astrophysics Data System (ADS)

Lu, Liang; Hattori, Toshiyuki; Hayashizaki, Noriyosu; Ishibashi, Takuya; Okamura, Masahiro; Kashiwagi, Hirotsugu; Takeuchi, Takeshi; Zhao, Hongwei; He, Yuan

2013-11-01

In order to verify the direct plasma injection scheme (DPIS), an acceleration test was carried out in 2001 using a radio frequency quadrupole (RFQ) heavy ion linear accelerator (linac) and a CO2-laser ion source (LIS) (Okamura et al., 2002) [1]. The accelerated carbon beam was observed successfully and the obtained current was 9.22 mA for C4+. To confirm the capability of the DPIS, we succeeded in accelerating 60 mA carbon ions with the DPIS in 2004 (Okamura et al., 2004; Kashiwagi and Hattori, 2004) [2,3]. We have studied a multi-beam type RFQ with an interdigital-H (IH) cavity that has a power-efficient structure in the low energy region. We designed and manufactured a two-beam type RFQ linac as a prototype for the multi-beam type linac; the beam acceleration test of carbon beams showed that it successfully accelerated from 5 keV/u up to 60 keV/u with an output current of 108 mA (2×54 mA/channel) (Ishibashi et al., 2011) [4]. We believe that the acceleration techniques of DPIS and the multi-beam type IH-RFQ linac are technical breakthroughs for heavy-ion inertial confinement fusion (HIF). The conceptual design of the RF linac with these techniques for HIF is studied. New accelerator-systems using these techniques for the HIF basic experiment are being designed to accelerate 400 mA carbon ions using four-beam type IH-RFQ linacs with DPIS. A model with a four-beam acceleration cavity was designed and manufactured to establish the proof of principle (PoP) of the accelerator.

On the Impact of a Quadratic Acceleration Term in the Analysis of Position Time Series

NASA Astrophysics Data System (ADS)

Bogusz, Janusz; Klos, Anna; Bos, Machiel Simon; Hunegnaw, Addisu; Teferle, Felix Norman

2016-04-01

The analysis of Global Navigation Satellite System (GNSS) position time series generally assumes that each of the coordinate component series is described by the sum of a linear rate (velocity) and various periodic terms. The residuals, the deviations between the fitted model and the observations, are then a measure of the epoch-to-epoch scatter and have been used for the analysis of the stochastic character (noise) of the time series. Often the parameters of interest in GNSS position time series are the velocities and their associated uncertainties, which have to be determined with the highest reliability. It is clear that not all GNSS position time series follow this simple linear behaviour. Therefore, we have added an acceleration term in the form of a quadratic polynomial function to the model in order to better describe the non-linear motion in the position time series. This non-linear motion could be a response to purely geophysical processes, for example, elastic rebound of the Earth's crust due to ice mass loss in Greenland, artefacts due to deficiencies in bias mitigation models, for example, of the GNSS satellite and receiver antenna phase centres, or any combination thereof. In this study we have simulated 20 time series with different stochastic characteristics such as white, flicker or random walk noise of length of 23 years. The noise amplitude was assumed at 1 mm/y-/4. Then, we added the deterministic part consisting of a linear trend of 20 mm/y (that represents the averaged horizontal velocity) and accelerations ranging from minus 0.6 to plus 0.6 mm/y2. For all these data we estimated the noise parameters with Maximum Likelihood Estimation (MLE) using the Hector software package without taken into account the non-linear term. In this way we set the benchmark to then investigate how the noise properties and velocity uncertainty may be affected by any un-modelled, non-linear term. The velocities and their uncertainties versus the accelerations for different types of noise are determined. Furthermore, we have selected 40 globally distributed stations that have a clear non-linear behaviour from two different International GNSS Service (IGS) analysis centers: JPL (Jet Propulsion Laboratory) and BLT (British Isles continuous GNSS Facility and University of Luxembourg Tide Gauge Benchmark Monitoring (TIGA) Analysis Center). We obtained maximum accelerations of -1.8±1.2 mm2/y and -4.5±3.3 mm2/y for the horizontal and vertical components, respectively. The noise analysis tests have shown that the addition of the non-linear term has significantly whitened the power spectra of the position time series, i.e. shifted the spectral index from flicker towards white noise.

The GALAXIE all-optical FEL project

NASA Astrophysics Data System (ADS)

Rosenzweig, J. B.; Arab, E.; Andonian, G.; Cahill, A.; Fitzmorris, K.; Fukusawa, A.; Hoang, P.; Jovanovic, I.; Marcus, G.; Marinelli, A.; Murokh, A.; Musumeci, P.; Naranjo, B.; O'Shea, B.; O'Shea, F.; Ovodenko, A.; Pogorelsky, I.; Putterman, S.; Roberts, K.; Shumail, M.; Tantawi, S.; Valloni, A.; Yakimenko, V.; Xu, G.

2012-12-01

We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 μm laser development, ultra-high brighness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.

Electric field stimulated growth of Zn whiskers

NASA Astrophysics Data System (ADS)

Niraula, D.; McCulloch, J.; Warrell, G. R.; Irving, R.; Karpov, V. G.; Shvydka, Diana

2016-07-01

We have investigated the impact of strong (˜104 V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

Suppressing beam-centroid motion in a long-pulse linear induction accelerator

NASA Astrophysics Data System (ADS)

Ekdahl, Carl; Abeyta, E. O.; Archuleta, R.; Bender, H.; Broste, W.; Carlson, C.; Cook, G.; Frayer, D.; Harrison, J.; Hughes, T.; Johnson, J.; Jacquez, E.; McCuistian, B. Trent; Montoya, N.; Nath, S.; Nielsen, K.; Rose, C.; Schulze, M.; Smith, H. V.; Thoma, C.; Tom, C. Y.

2011-12-01

The second axis of the dual-axis radiography of hydrodynamic testing (DARHT) facility produces up to four radiographs within an interval of 1.6μs. It does this by slicing four micropulses out of a 2-μs long electron beam pulse and focusing them onto a bremsstrahlung converter target. The 1.8-kA beam pulse is created by a dispenser cathode diode and accelerated to more than 16 MeV by the unique DARHT Axis-II linear induction accelerator (LIA). Beam motion in the accelerator would be a problem for multipulse flash radiography. High-frequency motion, such as from beam-breakup (BBU) instability, would blur the individual spots. Low-frequency motion, such as produced by pulsed-power variation, would produce spot-to-spot differences. In this article, we describe these sources of beam motion, and the measures we have taken to minimize it. Using the methods discussed, we have reduced beam motion at the accelerator exit to less than 2% of the beam envelope radius for the high-frequency BBU, and less than 1/3 of the envelope radius for the low-frequency sweep.

Skyshine radiation resulting from 6 MV and 10 MV photon beams from a medical accelerator.

PubMed

Elder, Deirdre H; Harmon, Joseph F; Borak, Thomas B

2010-07-01

Skyshine radiation scattered in the atmosphere above a radiation therapy accelerator facility can result in measurable dose rates at locations near the facility on the ground and at roof level. A Reuter Stokes RSS-120 pressurized ion chamber was used to measure exposure rates in the vicinity of a Varian Trilogy Linear Accelerator at the Colorado State University Veterinary Medical Center. The linear accelerator was used to deliver bremsstrahlung photons from 6 MeV and 10 MeV electron beams with several combinations of field sizes and gantry angles. An equation for modeling skyshine radiation in the vicinity of medical accelerators was published by the National Council on Radiation Protection and Measurements in 2005. However, this model did not provide a good fit to the observed dose rates at ground level or on the roof. A more accurate method of estimating skyshine may be to measure the exposure rate of the radiation exiting the roof of the facility and to scale the results using the graphs presented in this paper.

Perception of tilt (somatogravic illusion) in response to sustained linear acceleration during space flight

NASA Technical Reports Server (NTRS)

Clement, G.; Moore, S. T.; Raphan, T.; Cohen, B.

2001-01-01

During the 1998 Neurolab mission (STS-90), four astronauts were exposed to interaural and head vertical (dorsoventral) linear accelerations of 0.5 g and 1 g during constant velocity rotation on a centrifuge, both on Earth and during orbital space flight. Subjects were oriented either left-ear-out or right-ear-out (Gy centrifugation), or lay supine along the centrifuge arm with their head off-axis (Gz centrifugation). Pre-flight centrifugation, producing linear accelerations of 0.5 g and 1 g along the Gy (interaural) axis, induced illusions of roll-tilt of 20 degrees and 34 degrees for gravito-inertial acceleration (GIA) vector tilts of 27 degrees and 45 degrees , respectively. Pre-flight 0.5 g and 1 g Gz (head dorsoventral) centrifugation generated perceptions of backward pitch of 5 degrees and 15 degrees , respectively. In the absence of gravity during space flight, the same centrifugation generated a GIA that was equivalent to the centripetal acceleration and aligned with the Gy or Gz axes. Perception of tilt was underestimated relative to this new GIA orientation during early in-flight Gy centrifugation, but was close to the GIA after 16 days in orbit, when subjects reported that they felt as if they were 'lying on side'. During the course of the mission, inflight roll-tilt perception during Gy centrifugation increased from 45 degrees to 83 degrees at 1 g and from 42 degrees to 48 degrees at 0.5 g. Subjects felt 'upside-down' during in-flight Gz centrifugation from the first in-flight test session, which reflected the new GIA orientation along the head dorsoventral axis. The different levels of in-flight tilt perception during 0.5 g and 1 g Gy centrifugation suggests that other non-vestibular inputs, including an internal estimate of the body vertical and somatic sensation, were utilized in generating tilt perception. Interpretation of data by a weighted sum of body vertical and somatic vectors, with an estimate of the GIA from the otoliths, suggests that perception weights the sense of the body vertical more heavily early in-flight, that this weighting falls during adaptation to microgravity, and that the decreased reliance on the body vertical persists early post-flight, generating an exaggerated sense of tilt. Since graviceptors respond to linear acceleration and not to head tilt in orbit, it has been proposed that adaptation to weightlessness entails reinterpretation of otolith activity, causing tilt to be perceived as translation. Since linear acceleration during in-flight centrifugation was always perceived as tilt, not translation, the findings do not support this hypothesis.

A TE-mode accelerator

NASA Astrophysics Data System (ADS)

Takeuchi, S.; Sakai, K.; Matsumoto, M.; Sugihara, R.

1987-04-01

An accelerator is proposed in which a TE-mode wave is used to drive charged particles in contrast to the usual linear accelerators in which longitudinal electric fields or TM-mode waves are supposed to be utilized. The principle of the acceleration is based on the V(p) x B acceleration of a dynamo force acceleration, in which a charged particle trapped in a transverse wave feels a constant electric field (Faraday induction field) and subsequently is accelerated when an appropriate magnetic field is externally applied in the direction perpendicular to the wave propagation. A pair of dielectric plates is used to produce a slow TE mode. The conditions of the particle trapping the stabilization of the particle orbit are discussed.

EuCARD 2010: European coordination of accelerator research and development

NASA Astrophysics Data System (ADS)

Romaniuk, Ryszard S.

2010-09-01

Accelerators are basic tools of the experimental physics of elementary particles, nuclear physics, light sources of the fourth generation. They are also used in myriad other applications in research, industry and medicine. For example, there are intensely developed transmutation techniques for nuclear waste from nuclear power and atomic industries. The European Union invests in the development of accelerator infrastructures inside the framework programs to build the European Research Area. The aim is to build new accelerator research infrastructures, develop the existing ones, and generally make the infrastructures more available to competent users. The paper summarizes the first year of activities of the EU FP7 Project Capacities EuCARD -European Coordination of Accelerator R&D. EuCARD is a common venture of 37 European Accelerator Laboratories, Institutes, Universities and Industrial Partners involved in accelerator sciences and technologies. The project, initiated by ESGARD, is an Integrating Activity co-funded by the European Commission under Framework Program 7 - Capacities for a duration of four years, starting April 1st, 2009. Several teams from this country participate actively in this project. The contribution from Polish research teams concerns: photonic and electronic measurement - control systems, RF-gun co-design, thin-film superconducting technology, superconducting transport infrastructures, photon and particle beam measurements and control.

The Accelerated Schools Project: Pope Elementary School, 1993-94.

ERIC Educational Resources Information Center

Windward Oahu School District, Kailu, HI.

This report describes the first year of implementation of the 5-year Accelerated Schools Project (ASP) at Blanche Pope Elementary School in rural Oahu (Hawaii). ASP trains school staff and community members to transform governance, curriculum, and instruction in schools serving predominantly at-risk and minority, low-achieving students. In…

X-ray Laser Animated Fly-Through

ScienceCinema

None

2018-01-16

Take a tour with an electron's-eye-view through SLAC's revolutionary new X-ray laser facility with this 5 1/2 minute animation. See how the X-ray pulses are generated using the world's longest linear accelerator along with unique arrays of machinery specially designed for this one-of-a-kind tool. For more than 40 years, SLAC's two-mile-long linear accelerator (or linac) linac has produced high-energy electrons for cutting-edge physics experiments. Now, SLAC's linac has entered a new phase of its career with the creation of the Linac Coherent Light Source (LCLS).

ACCELERATORS: Preliminary application of turn-by-turn data analysis to the SSRF storage ring

NASA Astrophysics Data System (ADS)

Chen, Jian-Hui; Zhao, Zhen-Tang

2009-07-01

There is growing interest in utilizing the beam position monitor turn-by-turn (TBT) data to debug accelerators. TBT data can be used to determine the linear optics, coupled optics and nonlinear behaviors of the storage ring lattice. This is not only a useful complement to other methods of determining the linear optics such as LOCO, but also provides a possibility to uncover more hidden phenomena. In this paper, a preliminary application of a β function measurement to the SSRF storage ring is presented.

Failure of metoclopramide to control emesis or nausea due to stressful angular or linear acceleration

NASA Technical Reports Server (NTRS)

Kohl, Randall Lee

1987-01-01

Orally administered metoclopramide (REGLAN) at doses of 10 or 20 mg, 75 min prior to either stressful linear acceleration (parabolic flight) or cross-coupled accelerative semicircular canal stimulation in a rotating chair was evaluated for its ability to prevent emesis or nausea II, respectively. Although metoclopramide is an effective antiemetic agent that enhances gastric emptying and prevents cancer chemotherapy-induced emesis, it was not possible to demonstrate any significant (p less than 0.05) effects of this drug on motion sickness.

Microphysics of Waves and Instabilities in the Solar Wind and their Macro Manifestations in the Corona and Interplanetary Space

NASA Technical Reports Server (NTRS)

Habbal, Shadia R.; Gurman, Joseph (Technical Monitor)

2003-01-01

Investigations of the physical processes responsible for the acceleration of the solar wind were pursued with the development of two new solar wind codes: a hybrid code and a 2-D MHD code. Hybrid simulations were performed to investigate the interaction between ions and parallel propagating low frequency ion cyclotron waves in a homogeneous plasma. In a low-beta plasma such as the solar wind plasma in the inner corona, the proton thermal speed is much smaller than the Alfven speed. Vlasov linear theory predicts that protons are not in resonance with low frequency ion cyclotron waves. However, non-linear effect makes it possible that these waves can strongly heat and accelerate protons. This study has important implications for study of the corona and the solar wind. Low frequency ion cyclotron waves or Alfven waves are commonly observed in the solar wind. Until now, it is believed that these waves are not able to heat the solar wind plasma unless some cascading processes transfer the energy of these waves to high frequency part. However, this study shows that these waves may directly heat and accelerate protons non-linearly. This process may play an important role in the coronal heating and the solar wind acceleration, at least in some parameter space.

Analysis of head impacts during sub-elite hurling practice sessions.

PubMed

O'Sullivan, D; Roe, M; Blake, C

2018-06-01

The reported incidence of head and neck injuries in hurling is 0.12 per 1000 hours, but no previous research has quantified head impact characteristics in this sport. Here, a wireless accelerometer and gyroscope captured head impacts, in 20 senior club level hurling players. Peak linear and rotational acceleration and impact location were recorded during three hurling training sessions, each player participating once. A mean of 27.9 impacts (linear acceleration >10g) per player, per session were recorded; 1314 impacts during a total exposure time of 247 minutes. Only 2.6% impacts had peak linear acceleration of >70g and 6.2% had peak rotational acceleration >7900 rad/s 2 . There were significant differences in the number and magnitude of impacts, quantified by the accelerometer, between three training sessions of differing intensity (ŋ2 0.03-0.09, p < 0.001). This study represents a first step in quantifying head impacts during hurling, demonstrating the feasibility of this technology in the field. The sensors were able to discriminate between sessions of varying intensity. These data can be used to develop athlete monitoring protocols and may be useful in developing innovative helmet-testing standards for hurling. The potential for this technology to provide feedback has clinical utility for team medical personnel.

Accelerated Cure Project for Multiple Sclerosis

MedlinePlus

... main content Accelerating research toward a cure for multiple sclerosis Toggle navigation Search form Search Connect Volunteer Donate ... is to accelerate efforts toward a cure for multiple sclerosis by rapidly advancing research that determines its causes ...

Accelerated Test Method for Corrosion Protective Coatings Project

NASA Technical Reports Server (NTRS)

Falker, John; Zeitlin, Nancy; Calle, Luz

2015-01-01

This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as accurately and reliably as current long-term atmospheric exposure tests. This new accelerated test method will shorten the time needed to evaluate the corrosion protection performance of coatings for NASA's critical ground support structures. Lifetime prediction for spaceport structure coatings has a 5-year qualification cycle using atmospheric exposure. Current accelerated corrosion tests often provide false positives and negatives for coating performance, do not correlate to atmospheric corrosion exposure results, and do not correlate with atmospheric exposure timescales for lifetime prediction.

MO-FG-CAMPUS-JeP3-03: Detection of Unpredictable Patient Movement During SBRT Using a Single KV Projection of An On-Board CBCT System: Simulation Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Y; Sharp, G; Winey, B

Purpose: An unpredictable movement of a patient can occur during SBRT even when immobilization devices are applied. In the SBRT treatments using a conventional linear accelerator detection of such movements relies heavily on human interaction and monitoring. This study aims to detect such positional abnormalities in real-time by assessing intra-fractional gantry mounted kV projection images of a patient’s spine. Methods: We propose a self-CBCT image based spine tracking method consisting of the following steps: (1)Acquire a pre-treatment CBCT image; (2)Transform the CBCT volume according to the couch correction; (3)Acquire kV projections during treatment beam delivery; (4)Simultaneously with each acquisition generatemore » a DRR from the CBCT volume based-on the current projection geometry; (5)Perform an intensity gradient-based 2D registration between spine ROI images of the projection and the DRR images; (6)Report an alarm if the detected 2D displacement is beyond a threshold value. To demonstrate the feasibility, retrospective simulations were performed on 1,896 projections from nine CBCT sessions of three patients who received lung SBRT. The unpredictable movements were simulated by applying random rotations and translations to the reference CBCT prior to each DRR generation. As the ground truth, the 3D translations and/or rotations causing >3 mm displacement of the midpoint of the thoracic spine were regarded as abnormal. In the measurements, different threshold values of 2D displacement were tested to investigate sensitivity and specificity of the proposed method. Results: A linear relationship between the ground truth 3D displacement and the detected 2D displacement was observed (R{sup 2} = 0.44). When the 2D displacement threshold was set to 3.6 mm the overall sensitivity and specificity were 77.7±5.7% and 77.9±3.5% respectively. Conclusion: In this simulation study, it was demonstrated that intrafractional kV projections from an on-board CBCT system have a potential to detect unpredictable patient movement during SBRT. This research is funded by Interfractional Imaging Research Grant from Elekta.« less

Effective correlator for RadioAstron project

NASA Astrophysics Data System (ADS)

Sergeev, Sergey

This paper presents the implementation of programme FX-correlator for Very Long Baseline Interferometry, adapted for the project "RadioAstron". Software correlator implemented for heterogeneous computing systems using graphics accelerators. It is shown that for the task interferometry implementation of the graphics hardware has a high efficiency. The host processor of heterogeneous computing system, performs the function of forming the data flow for graphics accelerators, the number of which corresponds to the number of frequency channels. So, for the Radioastron project, such channels is seven. Each accelerator is perform correlation matrix for all bases for a single frequency channel. Initial data is converted to the floating-point format, is correction for the corresponding delay function and computes the entire correlation matrix simultaneously. Calculation of the correlation matrix is performed using the sliding Fourier transform. Thus, thanks to the compliance of a solved problem for architecture graphics accelerators, managed to get a performance for one processor platform Kepler, which corresponds to the performance of this task, the computing cluster platforms Intel on four nodes. This task successfully scaled not only on a large number of graphics accelerators, but also on a large number of nodes with multiple accelerators.

Acceleration of the direct reconstruction of linear parametric images using nested algorithms.

PubMed

Wang, Guobao; Qi, Jinyi

2010-03-07

Parametric imaging using dynamic positron emission tomography (PET) provides important information for biological research and clinical diagnosis. Indirect and direct methods have been developed for reconstructing linear parametric images from dynamic PET data. Indirect methods are relatively simple and easy to implement because the image reconstruction and kinetic modeling are performed in two separate steps. Direct methods estimate parametric images directly from raw PET data and are statistically more efficient. However, the convergence rate of direct algorithms can be slow due to the coupling between the reconstruction and kinetic modeling. Here we present two fast gradient-type algorithms for direct reconstruction of linear parametric images. The new algorithms decouple the reconstruction and linear parametric modeling at each iteration by employing the principle of optimization transfer. Convergence speed is accelerated by running more sub-iterations of linear parametric estimation because the computation cost of the linear parametric modeling is much less than that of the image reconstruction. Computer simulation studies demonstrated that the new algorithms converge much faster than the traditional expectation maximization (EM) and the preconditioned conjugate gradient algorithms for dynamic PET.

Effective Acceleration Model for the Arrival Time of Interplanetary Shocks driven by Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Paouris, Evangelos; Mavromichalaki, Helen

2017-12-01

In a previous work (Paouris and Mavromichalaki in Solar Phys. 292, 30, 2017), we presented a total of 266 interplanetary coronal mass ejections (ICMEs) with as much information as possible. We developed a new empirical model for estimating the acceleration of these events in the interplanetary medium from this analysis. In this work, we present a new approach on the effective acceleration model (EAM) for predicting the arrival time of the shock that preceds a CME, using data of a total of 214 ICMEs. For the first time, the projection effects of the linear speed of CMEs are taken into account in this empirical model, which significantly improves the prediction of the arrival time of the shock. In particular, the mean value of the time difference between the observed time of the shock and the predicted time was equal to +3.03 hours with a mean absolute error (MAE) of 18.58 hours and a root mean squared error (RMSE) of 22.47 hours. After the improvement of this model, the mean value of the time difference is decreased to -0.28 hours with an MAE of 17.65 hours and an RMSE of 21.55 hours. This improved version was applied to a set of three recent Earth-directed CMEs reported in May, June, and July of 2017, and we compare our results with the values predicted by other related models.

Community Petascale Project for Accelerator Science and Simulation: Advancing Computational Science for Future Accelerators and Accelerator Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spentzouris, P.; /Fermilab; Cary, J.

The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessarymore » accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors. ComPASS is in the first year of executing its plan to develop the next-generation HPC accelerator modeling tools. ComPASS aims to develop an integrated simulation environment that will utilize existing and new accelerator physics modules with petascale capabilities, by employing modern computing and solver technologies. The ComPASS vision is to deliver to accelerator scientists a virtual accelerator and virtual prototyping modeling environment, with the necessary multiphysics, multiscale capabilities. The plan for this development includes delivering accelerator modeling applications appropriate for each stage of the ComPASS software evolution. Such applications are already being used to address challenging problems in accelerator design and optimization. The ComPASS organization for software development and applications accounts for the natural domain areas (beam dynamics, electromagnetics, and advanced acceleration), and all areas depend on the enabling technologies activities, such as solvers and component technology, to deliver the desired performance and integrated simulation environment. The ComPASS applications focus on computationally challenging problems important for design or performance optimization to all major HEP, NP, and BES accelerator facilities. With the cost and complexity of particle accelerators rising, the use of computation to optimize their designs and find improved operating regimes becomes essential, potentially leading to significant cost savings with modest investment.« less

Gait event detection using linear accelerometers or angular velocity transducers in able-bodied and spinal-cord injured individuals.

PubMed

Jasiewicz, Jan M; Allum, John H J; Middleton, James W; Barriskill, Andrew; Condie, Peter; Purcell, Brendan; Li, Raymond Che Tin

2006-12-01

We report on three different methods of gait event detection (toe-off and heel strike) using miniature linear accelerometers and angular velocity transducers in comparison to using standard pressure-sensitive foot switches. Detection was performed with normal and spinal-cord injured subjects. The detection of end contact (EC), normally toe-off, and initial contact (IC) normally, heel strike was based on either foot linear accelerations or foot sagittal angular velocity or shank sagittal angular velocity. The results showed that all three methods were as accurate as foot switches in estimating times of IC and EC for normal gait patterns. In spinal-cord injured subjects, shank angular velocity was significantly less accurate (p<0.02). We conclude that detection based on foot linear accelerations or foot angular velocity can correctly identify the timing of IC and EC events in both normal and spinal-cord injured subjects.

Response of semicircular canal dependent units in vestibular nuclei to rotation of a linear acceleration vector without angular acceleration

PubMed Central

Benson, A. J.; Guedry, F. E.; Jones, G. Melvill

1970-01-01

1. Recent experiments have shown that rotation of a linear acceleration vector round the head can generate involuntary ocular nystagmus in the absence of angular acceleration. The present experiments examine the suggestion that adequate stimulation of the semicircular canals may contribute to this response. 2. Decerebrate cats were located in a stereotaxic device on a platform, slung from four parallel cables, which could be driven smoothly round a circular orbit without inducing significant angular movement of the platform. This Parallel Swing Rotation (PSR) generated a centripetal acceleration of 4·4 m/sec2 which rotated round the head at 0·52 rev/sec. 3. The discharge frequency of specifically lateral canal-dependent neural units in the vestibular nuclei of cats was recorded during PSR to right and left, and in the absence of motion. The dynamic responses to purely angular motion were also examined on a servo-driven turntable. 4. Without exception all proven canal-dependent cells examined (twenty-nine cells in nine cats) were more active during PSR in the direction of endolymph circulation assessed to be excitatory to the unit, than during PSR in the opposite direction. 5. The observed changes in discharge frequency are assessed to have been of a magnitude appropriate for the generation of the involuntary oculomotor response induced by the same stimulus in the intact animal. 6. The findings suggest that a linear acceleration vector which rotates in the plane of the lateral semicircular canals can be an adequate stimulus to ampullary receptors, though an explanation which invokes the modulation of canal cells by a signal dependent upon the sequential activation of macular receptors cannot be positively excluded. PMID:5501270

Short-range wakefields generated in the blowout regime of plasma-wakefield acceleration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stupakov, G.

In the past, calculation of wakefields generated by an electron bunch propagating in a plasma has been carried out in linear approximation, where the plasma perturbation can be assumed small and plasma equations of motion linearized. This approximation breaks down in the blowout regime where a high-density electron driver expels plasma electrons from its path and creates a cavity void of electrons in its wake. Here in this paper, we develop a technique that allows us to calculate short-range longitudinal and transverse wakes generated by a witness bunch being accelerated inside the cavity. Our results can be used for studiesmore » of the beam loading and the hosing instability of the witness bunch in plasma-wakefield and laser-wakefield acceleration.« less

Linear particle accelerator with seal structure between electrodes and insulators

DOEpatents

Broadhurst, John H.

1989-01-01

An electrostatic linear accelerator includes an electrode stack comprised of primary electrodes formed or Kovar and supported by annular glass insulators having the same thermal expansion rate as the electrodes. Each glass insulator is provided with a pair of fused-in Kovar ring inserts which are bonded to the electrodes. Each electrode is designed to define a concavo-convex particle trap so that secondary charged particles generated within the accelerated beam area cannot reach the inner surface of an insulator. Each insulator has a generated inner surface profile which is so configured that the electrical field at this surface contains no significant tangential component. A spark gap trigger assembly is provided, which energizes spark gaps protecting the electrodes affected by over voltage to prevent excessive energy dissipation in the electrode stack.

Short-range wakefields generated in the blowout regime of plasma-wakefield acceleration

DOE PAGES

Stupakov, G.

2018-04-02

In the past, calculation of wakefields generated by an electron bunch propagating in a plasma has been carried out in linear approximation, where the plasma perturbation can be assumed small and plasma equations of motion linearized. This approximation breaks down in the blowout regime where a high-density electron driver expels plasma electrons from its path and creates a cavity void of electrons in its wake. Here in this paper, we develop a technique that allows us to calculate short-range longitudinal and transverse wakes generated by a witness bunch being accelerated inside the cavity. Our results can be used for studiesmore » of the beam loading and the hosing instability of the witness bunch in plasma-wakefield and laser-wakefield acceleration.« less

Proton beam spatial distribution and Bragg peak imaging by photoluminescence of color centers in lithium fluoride crystals at the TOP-IMPLART linear accelerator

NASA Astrophysics Data System (ADS)

Piccinini, M.; Ronsivalle, C.; Ampollini, A.; Bazzano, G.; Picardi, L.; Nenzi, P.; Trinca, E.; Vadrucci, M.; Bonfigli, F.; Nichelatti, E.; Vincenti, M. A.; Montereali, R. M.

2017-11-01

Solid-state radiation detectors based on the photoluminescence of stable point defects in lithium fluoride crystals have been used for advanced diagnostics during the commissioning of the segment up to 27 MeV of the TOP-IMPLART proton linear accelerator for proton therapy applications, under development at ENEA C.R. Frascati, Italy. The LiF detectors high intrinsic spatial resolution and wide dynamic range allow obtaining two-dimensional images of the beam transverse intensity distribution and also identifying the Bragg peak position with micrometric precision by using a conventional optical fluorescence microscope. Results of the proton beam characterization, among which, the estimation of beam energy components and dynamics, are reported and discussed for different operating conditions of the accelerator.

Beam Size Measurement by Optical Diffraction Radiation and Laser System for Compton Polarimeter (in Chinese)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chuyu

2012-12-31

Beam diagnostics is an essential constituent of any accelerator, so that it is named as "organs of sense" or "eyes of the accelerator." Beam diagnostics is a rich field. A great variety of physical effects or physical principles are made use of in this field. Some devices are based on electro-magnetic influence by moving charges, such as faraday cups, beam transformers, pick-ups; Some are related to Coulomb interaction of charged particles with matter, such as scintillators, viewing screens, ionization chambers; Nuclear or elementary particle physics interactions happen in some other devices, like beam loss monitors, polarimeters, luminosity monitors; Some measuremore » photons emitted by moving charges, such as transition radiation, synchrotron radiation monitors and diffraction radiation-which is the topic of the first part of this thesis; Also, some make use of interaction of particles with photons, such as laser wire and Compton polarimeters-which is the second part of my thesis. Diagnostics let us perceive what properties a beam has and how it behaves in a machine, give us guideline for commissioning, controlling the machine and indispensable parameters vital to physics experiments. In the next two decades, the research highlight will be colliders (TESLA, CLIC, JLC) and fourth-generation light sources (TESLA FEL, LCLS, Spring 8 FEL) based on linear accelerator. These machines require a new generation of accelerator with smaller beam, better stability and greater efficiency. Compared with those existing linear accelerators, the performance of next generation linear accelerator will be doubled in all aspects, such as 10 times smaller horizontal beam size, more than 10 times smaller vertical beam size and a few or more times higher peak power. Furthermore, some special positions in the accelerator have even more stringent requirements, such as the interaction point of colliders and wigglor of free electron lasers. Higher performance of these accelerators increases the difficulty of diagnostics. For most cases, intercepting measurements are no longer acceptable, and nonintercepting method like synchrotron radiation monitor can not be applied to linear accelerators. The development of accelerator technology asks for simutanous diagnostics innovations, to expand the performance of diagnostic tools to meet the requirements of the next generation accelerators. Diffraction radiation and inverse Compton scattering are two of the most promising techniques, their nonintercepting nature avoids perturbance to the beam and damage to the instrumentation. This thesis is divided into two parts, beam size measurement by optical diffraction radiation and Laser system for Compton polarimeter. Diffraction radiation, produced by the interaction between the electric field of charged particles and the target, is related to transition radiation. Even though the theory of diffraction radiation has been discussed since 1960s, there are only a few experimental studies in recent years. The successful beam size measurement by optical diffraction radiation at CEBAF machine is a milestone: First of all, we have successfully demonstrated diffraction radiation as an effective nonintercepting diagnostics; Secondly, the simple linear relationship between the diffraction radiation image size and the actual beam size improves the reliability of ODR measurements; And, we measured the polarized components of diffraction radiation for the first time and I analyzed the contribution from edge radiation to diffraction radiation.« less

Acceleration and stability of a high-current ion beam in induction fields

NASA Astrophysics Data System (ADS)

Karas', V. I.; Manuilenko, O. V.; Tarakanov, V. P.; Federovskaya, O. V.

2013-03-01

A one-dimensional nonlinear analytic theory of the filamentation instability of a high-current ion beam is formulated. The results of 2.5-dimensional numerical particle-in-cell simulations of acceleration and stability of an annular compensated ion beam (CIB) in a linear induction particle accelerator are presented. It is shown that additional transverse injection of electron beams in magnetically insulated gaps (cusps) improves the quality of the ion-beam distribution function and provides uniform beam acceleration along the accelerator. The CIB filamentation instability in both the presence and the absence of an external magnetic field is considered.

Proceedings of the 1995 Particle Accelerator Conference and international Conference on High-Energy Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1996-01-01

Papers from the sixteenth biennial Particle Accelerator Conference, an international forum on accelerator science and technology held May 1–5, 1995, in Dallas, Texas, organized by Los Alamos National Laboratory (LANL) and Stanford Linear Accelerator Center (SLAC), jointly sponsored by the Institute of Electrical and Electronics Engineers (IEEE) Nuclear and Plasma Sciences Society (NPSS), the American Physical Society (APS) Division of Particles and Beams (DPB), and the International Union of Pure and Applied Physics (IUPAP), and conducted with support from the US Department of Energy, the National Science Foundation, and the Office of Naval Research.

BBU design of linear induction accelerator cells for radiography application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shang, C.C.; Chen, Y.J.; Gaporaso, G.J.

1997-05-06

There is an ongoing effort to develop accelerating modules for high-current electron accelerators for advanced radiography application. Accelerating modules with low beam-cavity coupling impedances along with gap designs with acceptable field stresses comprise a set of fundamental design criteria. We examine improved cell designs which have been developed for accelerator application in several radiographic operating regimes. We evaluate interaction impedances, analyze the effects of beam structure coupling on beam dynamics (beam break-up instability and corkscrew motion). We also provide estimates of coupling through interesting new high-gradient insulators and evaluate their potential future application in induction cells.

Final Report on Institutional Computing Project s15_hilaserion, “Kinetic Modeling of Next-Generation High-Energy, High-Intensity Laser-Ion Accelerators as an Enabling Capability”

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albright, Brian James; Yin, Lin; Stark, David James

This proposal sought of order 1M core-hours of Institutional Computing time intended to enable computing by a new LANL Postdoc (David Stark) working under LDRD ER project 20160472ER (PI: Lin Yin) on laser-ion acceleration. The project was “off-cycle,” initiating in June of 2016 with a postdoc hire.

High power ring methods and accelerator driven subcritical reactor application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tahar, Malek Haj

2016-08-07

High power proton accelerators allow providing, by spallation reaction, the neutron fluxes necessary in the synthesis of fissile material, starting from Uranium 238 or Thorium 232. This is the basis of the concept of sub-critical operation of a reactor, for energy production or nuclear waste transmutation, with the objective of achieving cleaner, safer and more efficient process than today’s technologies allow. Designing, building and operating a proton accelerator in the 500-1000 MeV energy range, CW regime, MW power class still remains a challenge nowadays. There is a limited number of installations at present achieving beam characteristics in that class, e.g.,more » PSI in Villigen, 590 MeV CW beam from a cyclotron, SNS in Oakland, 1 GeV pulsed beam from a linear accelerator, in addition to projects as the ESS in Europe, a 5 MW beam from a linear accelerator. Furthermore, coupling an accelerator to a sub-critical nuclear reactor is a challenging proposition: some of the key issues/requirements are the design of a spallation target to withstand high power densities as well as ensure the safety of the installation. These two domains are the grounds of the PhD work: the focus is on the high power ring methods in the frame of the KURRI FFAG collaboration in Japan: upgrade of the installation towards high intensity is crucial to demonstrate the high beam power capability of FFAG. Thus, modeling of the beam dynamics and benchmarking of different codes was undertaken to validate the simulation results. Experimental results revealed some major losses that need to be understood and eventually overcome. By developing analytical models that account for the field defects, one identified major sources of imperfection in the design of scaling FFAG that explain the important tune variations resulting in the crossing of several betatron resonances. A new formula is derived to compute the tunes and properties established that characterize the effect of the field imperfections on the transverse beam dynamics. The results obtained allow to develop a correction scheme to minimize the tune variations of the FFAG. This is the cornerstone of a new fixed tune non-scaling FFAG that represents a potential candidate for high power applications. As part of the developments towards high power at the KURRI FFAG, beam dynamics studies have to account for space charge effects. In that framework, models have been installed in the tracking code ZGOUBI to account for the self-interaction of the particles in the accelerator. Application to the FFAG studies is shown. Finally, one focused on the ADSR concept as a candidate to solve the problem of nuclear waste. In order to establish the accelerator requirements, one compared the performance of ADSR with other conventional critical reactors by means of the levelized cost of energy. A general comparison between the different accelerator technologies that can satisfy these requirements is finally presented. In summary, the main drawback of the ADSR technology is the high Levelized Cost Of Energy compared to other advanced reactor concepts that do not employ an accelerator. Nowadays, this is a show-stopper for any industrial application aiming at producing energy (without dealing with the waste problem). Besides, the reactor is not intrinsically safer than critical reactor concepts, given the complexity of managing the target interface between the accelerator and the reactor core.« less

Methods of Phase and Power Control in Magnetron Transmitters for Superconducting Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kazadevich, G.; Johnson, R.; Neubauer, M.

Various methods of phase and power control in magnetron RF sources of superconducting accelerators intended for ADS-class projects were recently developed and studied with conventional 2.45 GHz, 1 kW, CW magnetrons operating in pulsed and CW regimes. Magnetron transmitters excited by a resonant (injection-locking) phasemodulated signal can provide phase and power control with the rates required for precise stabilization of phase and amplitude of the accelerating field in Superconducting RF (SRF) cavities of the intensity-frontier accelerators. An innovative technique that can significantly increase the magnetron transmitter efficiency at the widerange power control required for superconducting accelerators was developed and verifiedmore » with the 2.45 GHz magnetrons operating in CW and pulsed regimes. High efficiency magnetron transmitters of this type can significantly reduce the capital and operation costs of the ADSclass accelerator projects.« less

SU-F-E-06: Dosimetric Characterization of Small Photons Beams of a Novel Linear Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Almonte, A; Polanco, G; Sanchez, E

2016-06-15

Purpose: The aim of the present contribution was to measure the main dosimetric quantities of small fields produced by UNIQUE and evaluate its matching with the corresponding dosimetric data of one 21EX conventional linear accelerator (Varian) in operation at the same center. The second step was to evaluate comparative performance of the EDGE diode detector and the PinPoint micro-ionization chamber for dosimetry of small fields. Methods: UNIQUE is configured with MLC (120 leaves with 0.5 cm leaf width) and a single low photon energy of 6 MV. Beam data were measured with scanning EDGE diode detector (volume of 0.019 mm{supmore » 3}), a PinPoint micro-ionization chamber (PTW) and for larger fields (≥ 4×4cm{sup 2}) a PTW Semi flex chamber (0.125 cm{sup 3}) was used. The scanning system used was the 3D cylindrical tank manufactured by Sun Nuclear, Inc. The measurement of PDD and profiles were done at 100 cm SSD and 1.5 depth; the relative output factors were measured at 10 cm depth. Results: PDD and the profile data showed less than 1% variation between the two linear accelerators for fields size between 2×2 cm{sup 2} and 5×5cm{sup 2}. Output factor differences was less than 1% for field sizes between 3×3 cm{sup 2} and 10×10 cm{sup 2} and less of 1.5 % for fields of 1.5×1.5 cm{sup 2} and 2×2 cm{sup 2} respectively. The dmax value of the EDGE diode detector, measured from the PDD, was 8.347 mm for 0.5×0,5cm{sup 2} for UNIQUE. The performance of EDGE diode detector was comparable for all measurements in small fields. Conclusion: UNIQUE linear accelerator show similar dosimetrics characteristics as conventional 21EX Varian linear accelerator for small, medium and large field sizes.EDGE detector show good performance by measuring dosimetrics quantities in small fields typically used in IMRT and radiosurgery treatments.« less

Batavia Boy Scouts | News

Science.gov Websites

Financial Officer Finance Section Office of the Chief Operating Officer Facilities Engineering Services Accelerator Division Accelerator Physics Center Office of the Chief Safety Officer Environment, Safety, Health and Quality Section Office of the Chief Project Officer Office of Project Support Services Office of

Osaka Symposium and New Accelerator Projects in Japan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Jie

1997-04-25

The purpose of this presentation was to participate as an invited speaker at the XV RCNP Osaka International Symposium on Multi-GeV High-Performance Accelerators and Related Technology to collaborate with Kyoto University on laser cooling and beam crystallization projects and to give seminars in Beijing and Shanghai on the Relativistic Heavy Ion Collider.

Accelerating Project and Process Improvement using Advanced Software Simulation Technology: From the Office to the Enterprise

DTIC Science & Technology

2010-04-29

Technology: From the Office Larry Smith Software Technology Support Center to the Enterprise 517 SMXS/MXDEA 6022 Fir Avenue Hill AFB, UT 84056 801...2010 to 00-00-2010 4. TITLE AND SUBTITLE Accelerating Project and Process Improvement using Advanced Software Simulation Technology: From the Office to

Construction of a High Energy Linear Accelerator for Research in Free Electron Lasers, Beam-Wave Interactions, Spectroscopy and Microcircuitry Fabrication.

DTIC Science & Technology

1985-12-03

will be published in Particle Accelerators. .. 0$ , . ’ ,,". . ". ..... " .. " ,", ’ - .’’--%:’ -i: .’ .’’" --.- ’ " FIL.M FD - * -" DIO1 DT IC

The Experimental Study of Rayleigh-Taylor Instability using a Linear Induction Motor Accelerator

NASA Astrophysics Data System (ADS)

Yamashita, Nicholas; Jacobs, Jeffrey

2009-11-01

The experiments to be presented utilize an incompressible system of two stratified miscible liquids of different densities that are accelerated in order to produce the Rayleigh-Taylor instability. Three liquid combinations are used: isopropyl alcohol with water, a calcium nitrate solution or a lithium polytungstate solution, giving Atwood numbers of 0.11, 0.22 and 0.57, respectively. The acceleration required to drive the instability is produced by two high-speed linear induction motors mounted to an 8 m tall drop tower. The motors are mounted in parallel and have an effective acceleration length of 1.7 m and are each capable of producing 15 kN of thrust. The liquid system is contained within a square acrylic tank with inside dimensions 76 x76x184 mm. The tank is mounted to an aluminum plate, which is driven by the motors to create constant accelerations in the range of 1-20 g's, though the potential exists for higher accelerations. Also attached to the plate are a high-speed camera and an LED backlight to provide continuous video of the instability. In addition, an accelerometer is used to provide acceleration measurements during each experiment. Experimental image sequences will be presented which show the development of a random three-dimensional instability from an unforced initial perturbation. Measurements of the mixing zone width will be compared with traditional growth models.

Laser-driven three-stage heavy-ion acceleration from relativistic laser-plasma interaction.

PubMed

Wang, H Y; Lin, C; Liu, B; Sheng, Z M; Lu, H Y; Ma, W J; Bin, J H; Schreiber, J; He, X T; Chen, J E; Zepf, M; Yan, X Q

2014-01-01

A three-stage heavy ion acceleration scheme for generation of high-energy quasimonoenergetic heavy ion beams is investigated using two-dimensional particle-in-cell simulation and analytical modeling. The scheme is based on the interaction of an intense linearly polarized laser pulse with a compound two-layer target (a front heavy ion layer + a second light ion layer). We identify that, under appropriate conditions, the heavy ions preaccelerated by a two-stage acceleration process in the front layer can be injected into the light ion shock wave in the second layer for a further third-stage acceleration. These injected heavy ions are not influenced by the screening effect from the light ions, and an isolated high-energy heavy ion beam with relatively low-energy spread is thus formed. Two-dimensional particle-in-cell simulations show that ∼100MeV/u quasimonoenergetic Fe24+ beams can be obtained by linearly polarized laser pulses at intensities of 1.1×1021W/cm2.

Efficient Homodifunctional Bimolecular Ring-Closure Method for Cyclic Polymers by Combining RAFT and Self-Accelerating Click Reaction.

PubMed

Qu, Lin; Sun, Peng; Wu, Ying; Zhang, Ke; Liu, Zhengping

2017-08-01

An efficient metal-free homodifunctional bimolecular ring-closure method is developed for the formation of cyclic polymers by combining reversible addition-fragmentation chain transfer (RAFT) polymerization and self-accelerating click reaction. In this approach, α,ω-homodifunctional linear polymers with azide terminals are prepared by RAFT polymerization and postmodification of polymer chain end groups. By virtue of sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DBA) as small linkers, well-defined cyclic polymers are then prepared using the self-accelerating double strain-promoted azide-alkyne click (DSPAAC) reaction to ring-close the azide end-functionalized homodifunctional linear polymer precursors. Due to the self-accelerating property of DSPAAC ring-closing reaction, this novel method eliminates the requirement of equimolar amounts of telechelic polymers and small linkers in traditional bimolecular ring-closure methods. It facilitates this method to efficiently and conveniently produce varied pure cyclic polymers by employing an excess molar amount of DBA small linkers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Responses to rotating linear acceleration vectors considered in relation to a model of the otolith organs. [human oculomotor response to transverse acceleration stress

NASA Technical Reports Server (NTRS)

Benson, A. J.; Barnes, G. R.

1973-01-01

Human subjects were exposed to a linear acceleration vector that rotated in the transverse plane of the skull without angular counterrotation. Lateral eye movements showed a sinusoidal change in slow phase velocity and an asymmetry or bias in the same direction as vector rotation. A model is developed that attributes the oculomotor response to otolithic mechanisms. It is suggested that the bias component is the manifestation of torsion of the statoconial plaque relative to the base of the utricular macula and that the sinusoidal component represents the translational oscillation of the statoconia. The model subsumes a hypothetical neural mechanism which allows x- and y-axis accelerations to be resolved. Derivation of equations of motion for the statoconial plaque in torsion and translation, which take into account forces acting in shear and normal to the macula, yield estimates of bias and sinusoidal components that are in qualitative agreement with the diverse experimental findings.

Berkeley Proton Linear Accelerator

DOE R&D Accomplishments Database

Alvarez, L. W.; Bradner, H.; Franck, J.; Gordon, H.; Gow, J. D.; Marshall, L. C.; Oppenheimer, F. F.; Panofsky, W. K. H.; Richman, C.; Woodyard, J. R.

1953-10-13

A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup 6} watts peak at 202.5 mc. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type.

Skyshine photon doses from 6 and 10 MV medical linear accelerators.

PubMed

de Paiva, Eduardo; da Rosa, Luiz A R

2012-01-05

The skyshine radiation phenomenon consists of the scattering of primary photon beams in the atmosphere above the roof of a medical linear accelerator facility, generating an additional dose at ground level in the vicinity of the treatment room. Thus, with respect to radioprotection, this situation plays an important role when the roof is designed with little shielding and there are buildings next to the radiotherapy treatment room. In literature, there are few reported skyshine-measured doses and these contain poor agreement with empirical calculations. In this work, we carried out measurements of skyshine photon dose rates produced from eight different 6 and 10 MV medical accelerators. Each measurement was performed outside the room facility, with the beam positioned in the upward direction, at a horizontal distance from the target and for a 40 cm × 40 cm maximum photon field size at the accelerator isocenter. Measured dose-equivalent rates results were compared with calculations obtained by an empirical expression, and differences between them deviated in one or more order of magnitude.

Linear accelerator: a reproducible, efficacious and cost effective alternative for blood irradiation.

PubMed

Shastry, Shamee; Ramya, B; Ninan, Jefy; Srinidhi, G C; Bhat, Sudha S; Fernandes, Donald J

2013-12-01

The dedicated devices for blood irradiation are available only at a few centers in developing countries thus the irradiation remains a service with limited availability due to prohibitive cost. To implement a blood irradiation program at our center using linear accelerator. The study is performed detailing the specific operational and quality assurance measures employed in providing a blood component-irradiation service at tertiary care hospital. X-rays generated from linear accelerator were used to irradiate the blood components. To facilitate and standardize the blood component irradiation, a blood irradiator box was designed and fabricated in acrylic. Using Elekta Precise Linear Accelerator, a dose of 25 Gy was delivered at the centre of the irradiation box. Standardization was done using five units of blood obtained from healthy voluntary blood donors. Each unit was divided to two parts. One aliquot was subjected to irradiation. Biochemical and hematological parameters were analyzed on various days of storage. Cost incurred was analyzed. Progressive increase in plasma hemoglobin, potassium and lactate dehydrogenase was noted in the irradiated units but all the parameters were within the acceptable range indicating the suitability of the product for transfusion. The irradiation process was completed in less than 30 min. Validation of the radiation dose done using TLD showed less than ± 3% variation. This study shows that that the blood component irradiation is within the scope of most of the hospitals in developing countries even in the absence of dedicated blood irradiators at affordable cost. Copyright © 2013 Elsevier Ltd. All rights reserved.

REVIEWS OF TOPICAL PROBLEMS: Acceleration of cosmic rays by shock waves

NASA Astrophysics Data System (ADS)

Berezhko, E. G.; Krymskiĭ, G. F.

1988-01-01

Theoretical work on various processes by which shock waves accelerate cosmic rays is reviewed. The most efficient of these processes, Fermi acceleration, is singled out for special attention. A linear theory for this process is presented. The results found on the basis of nonlinear models of Fermi acceleration, which incorporate the modification of the structure caused by the accelerated particles, are reported. There is a discussion of various possibilities for explaining the generation of high-energy particles observed in interplanetary and interstellar space on the basis of a Fermi acceleration mechanism. The acceleration by shock waves from supernova explosions is discussed as a possible source of galactic cosmic rays. The most important unresolved questions in the theory of acceleration of charged particles by shock waves are pointed out.

The biomechanics of concussion in unhelmeted football players in Australia: a case–control study

PubMed Central

McIntosh, Andrew S; Patton, Declan A; Fréchède, Bertrand; Pierré, Paul-André; Ferry, Edouard; Barthels, Tobias

2014-01-01

Objective Concussion is a prevalent brain injury in sport and the wider community. Despite this, little research has been conducted investigating the dynamics of impacts to the unprotected human head and injury causation in vivo, in particular the roles of linear and angular head acceleration. Setting Professional contact football in Australia. Participants Adult male professional Australian rules football players participating in 30 games randomly selected from 103 games. Cases selected based on an observable head impact, no observable symptoms (eg, loss-of-consciousness and convulsions), no on-field medical management and no injury recorded at the time. Primary and secondary outcome measures A data set for no-injury head impact cases comprising head impact locations and head impact dynamic parameters estimated through rigid body simulations using the MAthematical DYnamic MOdels (MADYMO) human facet model. This data set was compared to previously reported concussion case data. Results Qualitative analysis showed that the head was more vulnerable to lateral impacts. Logistic regression analyses of head acceleration and velocity components revealed that angular acceleration of the head in the coronal plane had the strongest association with concussion; tentative tolerance levels of 1747 rad/s2 and 2296 rad/s2 were reported for a 50% and 75% likelihood of concussion, respectively. The mean maximum resultant angular accelerations for the concussion and no-injury cases were 7951 rad/s2 (SD 3562 rad/s2) and 4300 rad/s2 (SD 3657 rad/s2), respectively. Linear acceleration is currently used in the assessment of helmets and padded headgear. The 50% and 75% likelihood of concussion values for resultant linear head acceleration in this study were 65.1 and 88.5 g, respectively. Conclusions As hypothesised by Holbourn over 70 years ago, angular acceleration plays an important role in the pathomechanics of concussion, which has major ramifications in terms of helmet design and other efforts to prevent and manage concussion. PMID:24844272

Tilt perception during dynamic linear acceleration.

PubMed

Seidman, S H; Telford, L; Paige, G D

1998-04-01

Head tilt is a rotation of the head relative to gravity, as exemplified by head roll or pitch from the natural upright orientation. Tilt stimulates both the otolith organs, owing to shifts in gravitational orientation, and the semicircular canals in response to head rotation, which in turn drive a variety of behavioral and perceptual responses. Studies of tilt perception typically have not adequately isolated otolith and canal inputs or their dynamic contributions. True tilt cannot readily dissociate otolith from canal influences. Alternatively, centrifugation generates centripetal accelerations that simulate tilt, but still entails a rotatory (canal) stimulus during important periods of the stimulus profiles. We reevaluated the perception of head tilt in humans, but limited the stimulus to linear forces alone, thus isolating the influence of otolith inputs. This was accomplished by employing a centrifugation technique with a variable-radius spinning sled. This allowed us to accelerate the sled to a constant angular velocity (128 degrees/s), with the subject centered, and then apply dynamic centripetal accelerations after all rotatory perceptions were extinguished. These stimuli were presented in the subjects' naso-occipital axis by translating the subjects 50 cm eccentrically either forward or backward. Centripetal accelerations were thus induced (0.25 g), which combined with gravity to yield a dynamically shifting gravitoinertial force simulating pitch-tilt, but without actually rotating the head. A magnitude-estimation task was employed to characterize the dynamic perception of pitch-tilt. Tilt perception responded sluggishly to linear acceleration, typically reaching a peak after 10-30 s. Tilt perception also displayed an adaptation phenomenon. Adaptation was manifested as a per-stimulus decline in perceived tilt during prolonged stimulation and a reversal aftereffect upon return to zero acceleration (i.e., recentering the subject). We conclude that otolith inputs can produce tilt perception in the absence of canal stimulation, and that this perception is subject to an adaptation phenomenon and low-pass filtering of its otolith input.

Graphical and PC-software analysis of volcano eruption precursors according to the Materials Failure Forecast Method (FFM)

NASA Astrophysics Data System (ADS)

Cornelius, Reinold R.; Voight, Barry

1995-03-01

The Materials Failure Forecasting Method for volcanic eruptions (FFM) analyses the rate of precursory phenomena. Time of eruption onset is derived from the time of "failure" implied by accelerating rate of deformation. The approach attempts to fit data, Ω, to the differential relationship Ω¨=AΩ˙, where the dot superscript represents the time derivative, and the data Ω may be any of several parameters describing the accelerating deformation or energy release of the volcanic system. Rate coefficients, A and α, may be derived from appropriate data sets to provide an estimate of time to "failure". As the method is still an experimental technique, it should be used with appropriate judgment during times of volcanic crisis. Limitations of the approach are identified and discussed. Several kinds of eruption precursory phenomena, all simulating accelerating creep during the mechanical deformation of the system, can be used with FFM. Among these are tilt data, slope-distance measurements, crater fault movements and seismicity. The use of seismic coda, seismic amplitude-derived energy release and time-integrated amplitudes or coda lengths are examined. Usage of cumulative coda length directly has some practical advantages to more rigorously derived parameters, and RSAM and SSAM technologies appear to be well suited to real-time applications. One graphical and four numerical techniques of applying FFM are discussed. The graphical technique is based on an inverse representation of rate versus time. For α = 2, the inverse rate plot is linear; it is concave upward for α < 2 and concave downward for α > 2. The eruption time is found by simple extrapolation of the data set toward the time axis. Three numerical techniques are based on linear least-squares fits to linearized data sets. The "linearized least-squares technique" is most robust and is expected to be the most practical numerical technique. This technique is based on an iterative linearization of the given rate-time series. The hindsight technique is disadvantaged by a bias favouring a too early eruption time in foresight applications. The "log rate versus log acceleration technique", utilizing a logarithmic representation of the fundamental differential equation, is disadvantaged by large data scatter after interpolation of accelerations. One further numerical technique, a nonlinear least-squares fit to rate data, requires special and more complex software. PC-oriented computer codes were developed for data manipulation, application of the three linearizing numerical methods, and curve fitting. Separate software is required for graphing purposes. All three linearizing techniques facilitate an eruption window based on a data envelope according to the linear least-squares fit, at a specific level of confidence, and an estimated rate at time of failure.

Beam dynamics in MABE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poukey, J.W.; Coleman, P.D.; Sanford, T.W.L.

1985-10-01

MABE is a multistage linear electron accelerator which accelerates up to nine beams in parallel. Nominal parameters per beam are 25 kA, final energy 7 MeV, and guide field 20 kG. We report recent progress via theory and simulation in understanding the beam dynamics in such a system. In particular, we emphasize our results on the radial oscillations and emittance growth for a beam passing through a series of accelerating gaps.

Bayesian integration and non-linear feedback control in a full-body motor task.

PubMed

Stevenson, Ian H; Fernandes, Hugo L; Vilares, Iris; Wei, Kunlin; Körding, Konrad P

2009-12-01

A large number of experiments have asked to what degree human reaching movements can be understood as being close to optimal in a statistical sense. However, little is known about whether these principles are relevant for other classes of movements. Here we analyzed movement in a task that is similar to surfing or snowboarding. Human subjects stand on a force plate that measures their center of pressure. This center of pressure affects the acceleration of a cursor that is displayed in a noisy fashion (as a cloud of dots) on a projection screen while the subject is incentivized to keep the cursor close to a fixed position. We find that salient aspects of observed behavior are well-described by optimal control models where a Bayesian estimation model (Kalman filter) is combined with an optimal controller (either a Linear-Quadratic-Regulator or Bang-bang controller). We find evidence that subjects integrate information over time taking into account uncertainty. However, behavior in this continuous steering task appears to be a highly non-linear function of the visual feedback. While the nervous system appears to implement Bayes-like mechanisms for a full-body, dynamic task, it may additionally take into account the specific costs and constraints of the task.

Accelerated pavement testing of low-volume paved roads with geocell reinforcement.

DOT National Transportation Integrated Search

2015-03-01

The Midwest States Accelerated Pavement Testing Pooled-Fund Program, financed by the highway : departments of Kansas, Iowa, Missouri, and New York, has supported an accelerated pavement testing (APT) project : to study the rehabilitation of low-volum...

Accelerated testing for studying pavement design and performance (FY 2003) : research summary.

DOT National Transportation Integrated Search

2008-01-01

The Midwest States Accelerated Pavement Testing Pooled Fund Program, financed by : the highway departments of Missouri, Iowa, Kansas and Nebraska, has supported an : accelerated pavement testing (APT) project to compare the performance of stabilized ...

Anderson acceleration of the Jacobi iterative method: An efficient alternative to Krylov methods for large, sparse linear systems

DOE PAGES

Pratapa, Phanisri P.; Suryanarayana, Phanish; Pask, John E.

2015-12-01

We employ Anderson extrapolation to accelerate the classical Jacobi iterative method for large, sparse linear systems. Specifically, we utilize extrapolation at periodic intervals within the Jacobi iteration to develop the Alternating Anderson–Jacobi (AAJ) method. We verify the accuracy and efficacy of AAJ in a range of test cases, including nonsymmetric systems of equations. We demonstrate that AAJ possesses a favorable scaling with system size that is accompanied by a small prefactor, even in the absence of a preconditioner. In particular, we show that AAJ is able to accelerate the classical Jacobi iteration by over four orders of magnitude, with speed-upsmore » that increase as the system gets larger. Moreover, we find that AAJ significantly outperforms the Generalized Minimal Residual (GMRES) method in the range of problems considered here, with the relative performance again improving with size of the system. As a result, the proposed method represents a simple yet efficient technique that is particularly attractive for large-scale parallel solutions of linear systems of equations.« less

Design of an X -band electron linear accelerator dedicated to decentralized 99Mo/99mTc supply: From beam energy selection to yield estimation

NASA Astrophysics Data System (ADS)

Jang, Jaewoong; Yamamoto, Masashi; Uesaka, Mitsuru

2017-10-01

The most frequently used radionuclide in diagnostic nuclear medicine, 99mTc, is generally obtained by the decay of its parent radionuclide, 99Mo. Recently, concerns have been raised over shortages of 99Mo/99mTc, owing to aging of the research reactors which have been supplying practically all of the global demand for 99Mo in a centralized fashion. In an effort to prevent such 99Mo/99mTc supply disruption and, furthermore, to ameliorate the underlying instability of the centralized 99Mo/99mTc supply chain, we designed an X -band electron linear accelerator which can be distributed over multiple regions, whereby 99Mo/99mTc can be supplied with improved accessibility. The electron beam energy was designed to be 35 MeV, at which an average beam power of 9.1 kW was calculated by the following beam dynamics analysis. Subsequent radioactivity modeling suggests that 11 of the designed electron linear accelerators can realize self-sufficiency of 99Mo/99mTc in Japan.

The International Linear Collider Technical Design Report - Volume 2: Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baer, Howard; Barklow, Tim; Fujii, Keisuke

2013-06-26

The International Linear Collider Technical Design Report (TDR) describes in four volumes the physics case and the design of a 500 GeV centre-of-mass energy linear electron-positron collider based on superconducting radio-frequency technology using Niobium cavities as the accelerating structures. The accelerator can be extended to 1 TeV and also run as a Higgs factory at around 250 GeV and on the Z0 pole. A comprehensive value estimate of the accelerator is give, together with associated uncertainties. It is shown that no significant technical issues remain to be solved. Once a site is selected and the necessary site-dependent engineering is carriedmore » out, construction can begin immediately. The TDR also gives baseline documentation for two high-performance detectors that can share the ILC luminosity by being moved into and out of the beam line in a "push-pull" configuration. These detectors, ILD and SiD, are described in detail. They form the basis for a world-class experimental programme that promises to increase significantly our understanding of the fundamental processes that govern the evolution of the Universe.« less

The International Linear Collider Technical Design Report - Volume 4: Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Behnke, Ties

2013-06-26

The International Linear Collider Technical Design Report (TDR) describes in four volumes the physics case and the design of a 500 GeV centre-of-mass energy linear electron-positron collider based on superconducting radio-frequency technology using Niobium cavities as the accelerating structures. The accelerator can be extended to 1 TeV and also run as a Higgs factory at around 250 GeV and on the Z0 pole. A comprehensive value estimate of the accelerator is give, together with associated uncertainties. It is shown that no significant technical issues remain to be solved. Once a site is selected and the necessary site-dependent engineering is carriedmore » out, construction can begin immediately. The TDR also gives baseline documentation for two high-performance detectors that can share the ILC luminosity by being moved into and out of the beam line in a "push-pull" configuration. These detectors, ILD and SiD, are described in detail. They form the basis for a world-class experimental programme that promises to increase significantly our understanding of the fundamental processes that govern the evolution of the Universe.« less

Anderson acceleration of the Jacobi iterative method: An efficient alternative to Krylov methods for large, sparse linear systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pratapa, Phanisri P.; Suryanarayana, Phanish; Pask, John E.

We employ Anderson extrapolation to accelerate the classical Jacobi iterative method for large, sparse linear systems. Specifically, we utilize extrapolation at periodic intervals within the Jacobi iteration to develop the Alternating Anderson–Jacobi (AAJ) method. We verify the accuracy and efficacy of AAJ in a range of test cases, including nonsymmetric systems of equations. We demonstrate that AAJ possesses a favorable scaling with system size that is accompanied by a small prefactor, even in the absence of a preconditioner. In particular, we show that AAJ is able to accelerate the classical Jacobi iteration by over four orders of magnitude, with speed-upsmore » that increase as the system gets larger. Moreover, we find that AAJ significantly outperforms the Generalized Minimal Residual (GMRES) method in the range of problems considered here, with the relative performance again improving with size of the system. As a result, the proposed method represents a simple yet efficient technique that is particularly attractive for large-scale parallel solutions of linear systems of equations.« less

On the Detectability of Acoustic Waves Induced Following Irradiation by a Radiotherapy Linear Accelerator.

PubMed

Hickling, Susannah; Leger, Pierre; El Naqa, Issam

2016-02-11

Irradiating an object with a megavoltage photon beam generated by a clinical radiotherapy linear accelerator (linac) induces acoustic waves through the photoacoustic effect. The detection and characterization of such acoustic waves has potential applications in radiation therapy dosimetry. The purpose of this work was to gain insight into the properties of such acoustic waves by simulating and experimentally detecting them in a well-defined system consisting of a metal block suspended in a water tank. A novel simulation workflow was developed by combining radiotherapy Monte Carlo and acoustic wave transport simulation techniques. Different set-up parameters such as photon beam energy, metal block depth, metal block width, and metal block material were varied, and the simulated and experimental acoustic waveforms showed the same relative amplitude trends and frequency variations for such setup changes. The simulation platform developed in this work can easily be extended to other irradiation situations, and will be an invaluable tool for developing a radiotherapy dosimetry system based on the detection of the acoustic waves induced following linear accelerator irradiation.

Dose characteristics of in-house-built collimators for stereotactic radiotherapy with a linear accelerator.

PubMed

Norrgård, F S; Sipilä, P M; Kulmala, J A; Minn, H R

1998-06-01

Dose characteristics of a stereotactic radiotherapy unit based on a standard Varian Clinac 4/100 4 MV linear accelerator, in-house-built Lipowitz collimators and the SMART stereotactic radiotherapy treatment planning software have been determined. Beam collimation is constituted from the standard collimators of the linear accelerator and a tertiary collimation consisting of a replaceable divergent Lipowitz collimator. Four collimators with isocentre diameters of 15, 25, 35 and 45 mm, respectively, were constructed. Beam characteristics were measured in air, acrylic or water with ionization chamber, photon diode, electron diode, diamond detector and film. Monte Carlo simulation was also applied. The radiation leakage under the collimators was less than 1% at 50 mm depth in water. Specific beam characteristics for each collimator were imported to SMART and dose planning with five non-coplanar converging 140 degrees arcs separated by 36 degrees angles was performed for treatment of a RANDO phantom. Dose verification was made with TLD and radiochromic film. The in-house-built collimators were found to be suitable for stereotactic radiotherapy and patient treatments with this system are in progress.

Contrast and Intensity upgrades to the Texas Petawatt laser for hadron generation and non-linear QED experiments

NASA Astrophysics Data System (ADS)

Hegelich, Bjorn M.; Arefiev, Alexey; Ditmire, Todd; Donovan, Michael E.; Dyer, Gillis; Gaul, Erhard; Labun, Lance; Luedtke, Scott; Martinez, Mikael; McCarry, Edward; Stark, David; Pomerantz, Ishay; Tiwari, Ganesh; Toncian, Toma

2015-11-01

Advances in laser-based hadron generation, especially with respect to particle energy, as well as reaching the new regime of radiation dominated plasmas and non-linear QED, require laser fields of Petavolts per meter that preferably interact with very high density, overcritical plasmas. To achieve these conditions we are upgrading the Texas Petawatt Laser both respect to on-target laser intensity and laser-contrast, aiming to reach intensities of ~ 5x1022 W/cm2 and pulse contrast parameters allowing the interaction with overcritical, yet ultrathin, sub-micron targets. We will report on the planned experiments aimed at ion acceleration, neutron generation and the first experimental measurement of radiation reactions to motivate the chosen upgrade parameters. We will further report on the technical changes to the laser and present first measurements of the achieved intensity and contrast parameters. This work was supported by NNSA cooperative agreement DE-NA0002008, the Defense Advanced Research Projects Agency's PULSE program (12-63-PULSE-FP014), the Air Force Office of Scientific Research (FA9550-14-1-0045) and the National Institute of Health SBIR.

Systems and methods for estimating the structure and motion of an object

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dani, Ashwin P; Dixon, Warren

2015-11-03

In one embodiment, the structure and motion of a stationary object are determined using two images and a linear velocity and linear acceleration of a camera. In another embodiment, the structure and motion of a stationary or moving object are determined using an image and linear and angular velocities of a camera.

Endocannabinoid signaling in hypothalamic circuits regulates arousal from general anesthesia in mice

PubMed Central

Zhong, Haixing; Tong, Li; Gu, Ning; Gao, Fang; Lu, Yacheng; Liu, Jingjing; Li, Xin; Bergeron, Richard; Pomeranz, Lisa E.; Wang, Feng; Luo, Chun-Xia; Ren, Yan; Wu, Sheng-Xi; Xie, Zhongcong; Xu, Lin; Li, Jinlian; Dong, Hailong; Xiong, Lize

2017-01-01

Consciousness can be defined by two major attributes: awareness of environment and self, and arousal, which reflects the level of awareness. The return of arousal after general anesthesia presents an experimental tool for probing the neural mechanisms that control consciousness. Here we have identified that systemic or intracerebral injection of the cannabinoid CB1 receptor (CB1R) antagonist AM281 into the dorsomedial nucleus of the hypothalamus (DMH) — but not the adjacent perifornical area (Pef) or the ventrolateral preoptic nucleus of the hypothalamus (VLPO) — accelerates arousal in mice recovering from general anesthesia. Anesthetics selectively activated endocannabinoid (eCB) signaling at DMH glutamatergic but not GABAergic synapses, leading to suppression of both glutamatergic DMH-Pef and GABAergic DMH-VLPO projections. Deletion of CB1R from widespread cerebral cortical or prefrontal cortical (PFC) glutamatergic neurons, including those innervating the DMH, mimicked the arousal-accelerating effects of AM281. In contrast, CB1R deletion from brain GABAergic neurons or hypothalamic glutamatergic neurons did not affect recovery time from anesthesia. Inactivation of PFC-DMH, DMH-VLPO, or DMH-Pef projections blocked AM281-accelerated arousal, whereas activation of these projections mimicked the effects of AM281. We propose that decreased eCB signaling at glutamatergic terminals of the PFC-DMH projection accelerates arousal from general anesthesia through enhancement of the excitatory DMH-Pef projection, the inhibitory DMH-VLPO projection, or both. PMID:28463228

A singular value decomposition linear programming (SVDLP) optimization technique for circular cone based robotic radiotherapy.

PubMed

Liang, Bin; Li, Yongbao; Wei, Ran; Guo, Bin; Xu, Xuang; Liu, Bo; Li, Jiafeng; Wu, Qiuwen; Zhou, Fugen

2018-01-05

With robot-controlled linac positioning, robotic radiotherapy systems such as CyberKnife significantly increase freedom of radiation beam placement, but also impose more challenges on treatment plan optimization. The resampling mechanism in the vendor-supplied treatment planning system (MultiPlan) cannot fully explore the increased beam direction search space. Besides, a sparse treatment plan (using fewer beams) is desired to improve treatment efficiency. This study proposes a singular value decomposition linear programming (SVDLP) optimization technique for circular collimator based robotic radiotherapy. The SVDLP approach initializes the input beams by simulating the process of covering the entire target volume with equivalent beam tapers. The requirements on dosimetry distribution are modeled as hard and soft constraints, and the sparsity of the treatment plan is achieved by compressive sensing. The proposed linear programming (LP) model optimizes beam weights by minimizing the deviation of soft constraints subject to hard constraints, with a constraint on the l 1 norm of the beam weight. A singular value decomposition (SVD) based acceleration technique was developed for the LP model. Based on the degeneracy of the influence matrix, the model is first compressed into lower dimension for optimization, and then back-projected to reconstruct the beam weight. After beam weight optimization, the number of beams is reduced by removing the beams with low weight, and optimizing the weights of the remaining beams using the same model. This beam reduction technique is further validated by a mixed integer programming (MIP) model. The SVDLP approach was tested on a lung case. The results demonstrate that the SVD acceleration technique speeds up the optimization by a factor of 4.8. Furthermore, the beam reduction achieves a similar plan quality to the globally optimal plan obtained by the MIP model, but is one to two orders of magnitude faster. Furthermore, the SVDLP approach is tested and compared with MultiPlan on three clinical cases of varying complexities. In general, the plans generated by the SVDLP achieve steeper dose gradient, better conformity and less damage to normal tissues. In conclusion, the SVDLP approach effectively improves the quality of treatment plan due to the use of the complete beam search space. This challenging optimization problem with the complete beam search space is effectively handled by the proposed SVD acceleration.

A singular value decomposition linear programming (SVDLP) optimization technique for circular cone based robotic radiotherapy

NASA Astrophysics Data System (ADS)

Liang, Bin; Li, Yongbao; Wei, Ran; Guo, Bin; Xu, Xuang; Liu, Bo; Li, Jiafeng; Wu, Qiuwen; Zhou, Fugen

2018-01-01

With robot-controlled linac positioning, robotic radiotherapy systems such as CyberKnife significantly increase freedom of radiation beam placement, but also impose more challenges on treatment plan optimization. The resampling mechanism in the vendor-supplied treatment planning system (MultiPlan) cannot fully explore the increased beam direction search space. Besides, a sparse treatment plan (using fewer beams) is desired to improve treatment efficiency. This study proposes a singular value decomposition linear programming (SVDLP) optimization technique for circular collimator based robotic radiotherapy. The SVDLP approach initializes the input beams by simulating the process of covering the entire target volume with equivalent beam tapers. The requirements on dosimetry distribution are modeled as hard and soft constraints, and the sparsity of the treatment plan is achieved by compressive sensing. The proposed linear programming (LP) model optimizes beam weights by minimizing the deviation of soft constraints subject to hard constraints, with a constraint on the l 1 norm of the beam weight. A singular value decomposition (SVD) based acceleration technique was developed for the LP model. Based on the degeneracy of the influence matrix, the model is first compressed into lower dimension for optimization, and then back-projected to reconstruct the beam weight. After beam weight optimization, the number of beams is reduced by removing the beams with low weight, and optimizing the weights of the remaining beams using the same model. This beam reduction technique is further validated by a mixed integer programming (MIP) model. The SVDLP approach was tested on a lung case. The results demonstrate that the SVD acceleration technique speeds up the optimization by a factor of 4.8. Furthermore, the beam reduction achieves a similar plan quality to the globally optimal plan obtained by the MIP model, but is one to two orders of magnitude faster. Furthermore, the SVDLP approach is tested and compared with MultiPlan on three clinical cases of varying complexities. In general, the plans generated by the SVDLP achieve steeper dose gradient, better conformity and less damage to normal tissues. In conclusion, the SVDLP approach effectively improves the quality of treatment plan due to the use of the complete beam search space. This challenging optimization problem with the complete beam search space is effectively handled by the proposed SVD acceleration.

Soviet Hadron Collider

NASA Astrophysics Data System (ADS)

Kotchetkov, Dmitri

2017-01-01

Rapid growth of the high energy physics program in the USSR during 1960s-1970s culminated with a decision to build the Accelerating and Storage Complex (UNK) to carry out fixed target and colliding beam experiments. The UNK was to have three rings. One ring was to be built with conventional magnets to accelerate protons up to the energy of 600 GeV. The other two rings were to be made from superconducting magnets, each ring was supposed to accelerate protons up to the energy of 3 TeV. The accelerating rings were to be placed in an underground tunnel with a circumference of 21 km. As a 3 x 3 TeV collider, the UNK would make proton-proton collisions with a luminosity of 4 x 1034 cm-1s-1. Institute for High Energy Physics in Protvino was a project leading institution and a site of the UNK. Accelerator and detector research and development studies were commenced in the second half of 1970s. State Committee for Utilization of Atomic Energy of the USSR approved the project in 1980, and the construction of the UNK started in 1983. Political turmoil in the Soviet Union during late 1980s and early 1990s resulted in disintegration of the USSR and subsequent collapse of the Russian economy. As a result of drastic reduction of funding for the UNK, in 1993 the project was restructured to be a 600 GeV fixed target accelerator only. While the ring tunnel and proton injection line were completed by 1995, and 70% of all magnets and associated accelerator equipment were fabricated, lack of Russian federal funding for high energy physics halted the project at the end of 1990s.

The GALAXIE all-optical FEL project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenzweig, J. B.; Arab, E.; Andonian, G.

2012-12-21

We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 {mu}m laser development, ultra-highmore » brightness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.« less

SU-F-T-475: An Evaluation of the Overlap Between the Acceptance Testing and Commissioning Processes for Conventional Medical Linear Accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morrow, A; Rangaraj, D; Perez-Andujar, A

2016-06-15

Purpose: This work’s objective is to determine the overlap of processes, in terms of sub-processes and time, between acceptance testing and commissioning of a conventional medical linear accelerator and to evaluate the time saved by consolidating the two processes. Method: A process map for acceptance testing for medical linear accelerators was created from vendor documentation (Varian and Elekta). Using AAPM TG-106 and inhouse commissioning procedures, a process map was created for commissioning of said accelerators. The time to complete each sub-process in each process map was evaluated. Redundancies in the processes were found and the time spent on each weremore » calculated. Results: Mechanical testing significantly overlaps between the two processes - redundant work here amounts to 9.5 hours. Many beam non-scanning dosimetry tests overlap resulting in another 6 hours of overlap. Beam scanning overlaps somewhat - acceptance tests include evaluating PDDs and multiple profiles but for only one field size while commissioning beam scanning includes multiple field sizes and depths of profiles. This overlap results in another 6 hours of rework. Absolute dosimetry, field outputs, and end to end tests are not done at all in acceptance testing. Finally, all imaging tests done in acceptance are repeated in commissioning, resulting in about 8 hours of rework. The total time overlap between the two processes is about 30 hours. Conclusion: The process mapping done in this study shows that there are no tests done in acceptance testing that are not also recommended to do for commissioning. This results in about 30 hours of redundant work when preparing a conventional linear accelerator for clinical use. Considering these findings in the context of the 5000 linacs in the United states, consolidating acceptance testing and commissioning would have allowed for the treatment of an additional 25000 patients using no additional resources.« less

Effects of Frequency and Motion Paradigm on Perception of Tilt and Translation During Periodic Linear Acceleration

NASA Technical Reports Server (NTRS)

Beaton, K. H.; Holly, J. E.; Clement, G. R.; Wood, Scott J.

2009-01-01

Previous studies have demonstrated an effect of frequency on the gain of tilt and translation perception. Results from different motion paradigms are often combined to extend the stimulus frequency range. For example, Off-Vertical Axis Rotation (OVAR) and Variable Radius Centrifugation (VRC) are useful to test low frequencies of linear acceleration at amplitudes that would require impractical sled lengths. The purpose of this study was to compare roll-tilt and lateral translation motion perception in 12 healthy subjects across four paradigms: OVAR, VRC, sled translation and rotation about an earth-horizontal axis. Subjects were oscillated in darkness at six frequencies from 0.01875 to 0.6 Hz (peak acceleration equivalent to 10 deg, less for sled motion below 0.15 Hz). Subjects verbally described the amplitude of perceived tilt and translation, and used a joystick to indicate the direction of motion. Consistent with previous reports, tilt perception gain decreased as a function of stimulus frequency in the motion paradigms without concordant canal tilt cues (OVAR, VRC and Sled). Translation perception gain was negligible at low stimulus frequencies and increased at higher frequencies. There were no significant differences between the phase of tilt and translation, nor did the phase significantly vary across stimulus frequency. There were differences in perception gain across the different paradigms. Paradigms that included actual tilt stimuli had the larger tilt gains, and paradigms that included actual translation stimuli had larger translation gains. In addition, the frequency at which there was a crossover of tilt and translation gains appeared to vary across motion paradigm between 0.15 and 0.3 Hz. Since the linear acceleration in the head lateral plane was equivalent across paradigms, differences in gain may be attributable to the presence of linear accelerations in orthogonal directions and/or cognitive aspects based on the expected motion paths.