Science.gov

Sample records for 450-mev positron linac

  1. Production of slow-positron beams with an electron linac

    SciTech Connect

    Howell, R.H.; Alvarez, R.A.; Stanek, M.

    1982-03-26

    Intense, pulsed beams of low-energy positrons have been produced by a high-energy beam from an electron linac. The production efficiency for low-energy positrons has been determined for electrons with 60 to 120 MeV energy, low-energy positron beams from a linac can be of much higher intensity than those beams currently derived from radioactive sources.

  2. Beam dynamic simulation and optimization of the CLIC positron source and the capture linac

    NASA Astrophysics Data System (ADS)

    Bayar, C.; Doebert, S.; Ciftci, A. K.

    2016-03-01

    The CLIC Positron Source is based on the hybrid target composed of a crystal and an amorphous target. Simulations have been performed from the exit of the amorphous target to the end of pre-injector linac which captures and accelerates the positrons to an energy of 200 MeV. Simulations are performed by the particle tracking code PARMELA. The magnetic field of the AMD is represented in PARMELA by simple coils. Two modes are applied in this study. The first one is accelerating mode based on acceleration after the AMD. The second one is decelerating mode based on deceleration in the first accelerating structure. It is shown that the decelerating mode gives a higher yield for the e+ beam in the end of the Pre-Injector Linac.

  3. A new scheme to accumulate positrons in a Penning-Malmberg trap with a linac-based positron pulsed source

    SciTech Connect

    Dupre, P.

    2013-03-19

    The Gravitational Behaviour of Antimatter at Rest experiment (GBAR) is designed to perform a direct measurement of the weak equivalence principle on antimatter by measuring the acceleration of anti-hydrogen atoms in the gravitational field of the Earth. The experimental scheme requires a high density positronium (Ps) cloud as a target for antiprotons, provided by the Antiproton Decelerator (AD) - Extra Low Energy Antiproton Ring (ELENA) facility at CERN. The Ps target will be produced by a pulse of few 10{sup 10} positrons injected onto a positron-positronium converter. For this purpose, a slow positron source using an electron Linac has been constructed at Saclay. The present flux is comparable with that of {sup 22}Na-based sources using solid neon moderator. A new positron accumulation scheme with a Penning-Malmberg trap has been proposed taking advantage of the pulsed time structure of the beam. In the trap, the positrons are cooled by interaction with a dense electron plasma. The overall trapping efficiency has been estimated to be {approx}70% by numerical simulations.

  4. Development of mini linac-based positron source and an efficient positronium convertor for positively charged antihydrogen production

    NASA Astrophysics Data System (ADS)

    Muranaka, T.; Debu, P.; Dupré, P.; Liszkay, L.; Mansoulie, B.; Pérez, P.; Rey, J. M.; Ruiz, N.; Sacquin, Y.; Crivelli, P.; Gendotti, U.; Rubbia, A.

    2010-04-01

    We have installed in Saclay a facility for an intense positron source in November 2008. It is based on a compact 5.5 MeV electron linac connected to a reaction chamber with a tungsten target inside to produce positrons via pair production. The expected production rate for fast positrons is 5·1011 per second. The study of moderation of fast positrons and the construction of a slow positron trap are underway. In parallel, we have investigated an efficient positron-positronium convertor using porous silica materials. These studies are parts of a project to produce positively charged antihydrogen ions aiming to demonstrate the feasibility of a free fall antigravity measurement of neutral antihydrogen.

  5. Positron source investigation by using CLIC drive beam for Linac-LHC based e+p collider

    NASA Astrophysics Data System (ADS)

    Arιkan, Ertan; Aksakal, Hüsnü

    2012-08-01

    Three different methods which are alternately conventional, Compton backscattering and Undulator based methods employed for the production of positrons. The positrons to be used for e+p collisions in a Linac-LHC (Large Hadron Collider) based collider have been studied. The number of produced positrons as a function of drive beam energy and optimum target thickness has been determined. Three different targets have been used as a source investigation which are W75-Ir25, W75-Ta25, and W75-Re25 for three methods. Estimated number of the positrons has been performed with FLUKA simulation code. Then, these produced positrons are used for following Adiabatic matching device (AMD) and capture efficiency is determined. Then e+p collider luminosity corresponding to the methods mentioned above have been calculated by CAIN code.

  6. Special SLC linac developments

    SciTech Connect

    Seeman, J.T.; Sheppard, J.C.

    1986-04-01

    The linac of the SLAC Linear Collider (SLC) is required to accelerate several intense electron and positron bunches to high energy while maintaining their small transverse dimensions and energy spectra. Many of the linac systems have been upgraded to the new stringent SLC design criteria. The remaining systems will be completed in the summer of 1986. Special instruments and controls have been developed to monitor and manipulate these small but potent beams. A brief review of the SLC requirements is given. A broad survey of the recent development is made encompassing longitudinal and transverse wakefield reductions, Landau damping, energy and position feedback systems, beam diagnostic and beam current fluctuations.

  7. Positron microprobe at LLNL

    SciTech Connect

    Asoka, P; Howell, R; Stoeffl, W

    1998-11-01

    The electron linac based positron source at Lawrence Livermore National Laboratory (LLNL) provides the world's highest current beam of keV positrons. We are building a positron microprobe that will produce a pulsed, focused positron beam for 3-dimensional scans of defect size and concentration with sub-micron resolution. The widely spaced and intense positron packets from the tungsten moderator at the end of the 100 MeV LLNL linac are captured and trapped in a magnetic bottle. The positrons are then released in 1 ns bunches at a 20 MHz repetition rate. With a three-stage re-moderation we will compress the cm-sized original beam to a 1 micro-meter diameter final spot on the target. The buncher will compress the arrival time of positrons on the target to less than 100 ps. A detector array with up to 60 BaF2 crystals in paired coincidence will measure the annihilation radiation with high efficiency and low background. The energy of the positrons can be varied from less than 1 keV up to 50 keV.

  8. Comments on a linac based beauty factory

    SciTech Connect

    Samuel Heifets; Geoffrey Krafft; C. McDowell; M. Fripp

    1990-02-01

    A consistent set of parameters is given for a B-factory based on collisions of an electron beam from a SRF linac with the positron beam in a storage ring. An optimized lattice, an impedance estimate, a study of beam stability, and a discussion of collisions with large disruption parameters are included.

  9. Applications for the RFD linac structure

    NASA Astrophysics Data System (ADS)

    Swenson, Donald A.

    2001-07-01

    With the successful completion and operation of the "Proof-of-Principle" prototype of the Rf Focused Drift tube (RFD) linac structure, our attention has now turned to the identification of the first applications for this new compact and economical linac structure. The principal medical applications are for the production of short-lived radioisotopes for the positron emission tomography (PET and SPECT) application, epithermal neutron beams for the boron neutron capture therapy (BNCT) application, and nanoamperes of energetic (250 MeV) protons for proton therapy. The structure can be configured as a compact injector linac for proton synchrotrons. The structure can be configured as a pulsed cold neutron source to support cold neutron physics and its applications. The principal industrial applications include nondestructive testing (NDT), thermal neutron radiography (TNR), thermal neutron analysis (TNA), and pulsed fast neutron analysis (PFNA). Brief descriptions of these RFD-linac-based systems will be presented.

  10. The Japanese Positron Factory

    NASA Astrophysics Data System (ADS)

    Okada, S.; Sunaga, H.; Kaneko, H.; Takizawa, H.; Kawasuso, A.; Yotsumoto, K.; Tanaka, R.

    1999-06-01

    The Positron Factory has been planned at Japan Atomic Energy Research Institute (JAERI). The factory is expected to produce linac-based monoenergetic positron beams having world-highest intensities of more than 1010e+/sec, which will be applied for R&D of materials science, biotechnology and basic physics & chemistry. In this article, results of the design studies are demonstrated for the following essential components of the facilities: 1) Conceptual design of a high-power electron linac with 100 MeV in beam energy and 100 kW in averaged beam power, 2) Performance tests of the RF window in the high-power klystron and of the electron beam window, 3) Development of a self-driven rotating electron-to-positron converter and the performance tests, 4) Proposal of multi-channel beam generation system for monoenergetic positrons, with a series of moderator assemblies based on a newly developed Monte Carlo simulation and the demonstrative experiment, 5) Proposal of highly efficient moderator structures, 6) Conceptual design of a local shield to suppress the surrounding radiation and activation levels.

  11. APS linac klystron and accelerating structure gain measurements and klystron PFN voltage regulation requirements

    SciTech Connect

    Sereno, N.S.

    1997-07-01

    This note details measurements of the APS positron linac klystron and accelerating structure gain and presents an analysis of the data using fits to simple mathematical models. The models are used to investigate the sensitivity of the energy dependence of the output positron beam to klystron parameters. The gain measurements are separated into two parts: first, the energy gains of the accelerating structures of the positron linac are measured as a function of output power of the klystron; second, the klystron output power is measured as a function of input drive power and pulse forming network (PFN) voltage. This note concentrates on the positron linac rf and its performance as it directly affects the energy stability of the positron beam injected into the positron accumulator ring (PAR). Ultimately it is important to be able to minimize beam energy variations to maximize the PAR accumulation efficiency.

  12. Beam steering in the SLC linac

    SciTech Connect

    Sheppard, J.C.; Lee, M.J.; Ross, M.C.; Seeman, J.T.; Stiening, R.F.; Woodley, M.D.

    1985-02-01

    In order to control emittance growth due to transverse wakefields it will be necessary to transport electrons and positrons through the Stanford Linear Collider (SLC) linac to within a hundred ..mu..m of the centers of the linac irises. Beam centering will be accomplished using computer routines to read stripline beam position monitors and in turn correct the orbits with dipole magnets. Several different steering algorithms have been investigated using electrons in the first third of the SLC linac lattice. The most promising scheme is a cascade of modified ''three-bumps'' in conjunction with long spanning harmonic corrections. General features of the orbit correcting software are discussed along with the mathematical recipes for correction. Experimental results and a discussion of future plans are presented.

  13. Beam steering in the SLC linac

    SciTech Connect

    Sheppard, J.C.; Lee, M.J.; Ross, M.C.; Seeman, J.T.; Stiening, R.F.; Woodley, M.D.

    1985-10-01

    In order to control emittance growth due to transverse wakefields it will be necessary to transport electrons and positrons through the Stanford Linear Collider (SLC) linac to within a hundred ..mu..m of the centers of the linac irises. Beam centering will be accomplished using computer routines to read stripline beam position monitors and in turn correct the orbits with dipole magnets. Several different steering algorithms have been investigated using electrons in the first third of the SLC linac lattice. The most promising scheme is a cascade of modified ''three-bumps'' in conjunction with long spanning harmonic corrections. General features of the orbit correcting software are discussed along with the mathematical recipes for correction. Experimental results and a discussion of future plans are presented.

  14. ILC Linac R&D at SLAC

    SciTech Connect

    Adolphsen, C.; /SLAC

    2006-08-09

    Since the ITRP recommendation in August 2004 to use superconducting rf technology for a next generation linear collider, the former NLC Group at SLAC has been actively pursuing a broad range of R&D for this collider (the ILC). In this paper, the programs concerning linac technology are reviewed. Current activities include the development of a Marx-style modulator and a 10 MW sheet-beam klystron, operation of an L-band (1.3 GHz) rf source using an SNS HVCM modulator and commercial klystrons, design of a more efficient and less costly rf distribution system, construction of a coupler component test stand, fabrication of a prototype positron capture cavity, beam tests of prototype S-band linac beam position monitors and preparations for magnetic center stability measurements of a prototype SC linac quad.

  15. Summary of Linac Group discussions

    SciTech Connect

    Schaffer, G.

    1989-01-01

    This paper discusses upgrading of the LAMPF I linac. Particular topics discussed are: sources of and cures for linac beam halos, ion source, RFQ, chopper and drift-tube linac, cavity-coupled linac, superconducting linac structure, new rf power sources, EHF linac design, and cost projections. (LSP)

  16. Acceleration of high charge density electron beams in the SLAC linac

    SciTech Connect

    Sheppard, J.C.; Clendenin, J.E.; Jobe, R.K.; Lueth, V.G.; Millich, A.; Ross, M.C.; Seeman, J.T.; Stiening, R.F.

    1984-01-01

    The SLAC Linear Collider (SLC) will require both electron and positron beams of very high charge density and low emittance to be accelerated to about 50 GeV in the SLAC 3-km linac. The linac is in the process of being improved to meet this requirement. The program to accelerate an electron beam of high charge density through the first third of the SLC linac is described and the experimental results are discussed. 7 references, 5 figures.

  17. Beam based alignment of sector-1 of the SLC linac

    SciTech Connect

    Emma, P.

    1992-03-01

    A technique is described which uses the beam to simultaneously measure quadrupole magnet and beam position monitor (BPM) transverse misalignments. The technique is applied to sector-1 of the SLC linac where simultaneous acceleration of electron and positron beams with minimal steering elements and BPMs makes quadrupole alignment critical for high transmission of the large transverse emittance positron beam. Simulation results as well as measurements are presented.

  18. The RIA driver linac.

    SciTech Connect

    Shepard, K. W.

    2002-09-23

    The driver linac for the U.S. RIA project will be a 1.4 GV superconducting linac capable of accelerating the full mass range of ions from 900 MeV protons to 400 MeV/u uranium, and delivering a cw beam of 400 kW shared by at least two targets simultaneously. Elements of the linac are being developed at several U.S. laboratories. The current status of linac design and development is reviewed with emphasis on changes in the baseline design since the last linac conference.

  19. Positron microscopy

    SciTech Connect

    Hulett, L.D. Jr.; Xu, J.

    1995-02-01

    The negative work function property that some materials have for positrons make possible the development of positron reemission microscopy (PRM). Because of the low energies with which the positrons are emitted, some unique applications, such as the imaging of defects, can be made. The history of the concept of PRM, and its present state of development will be reviewed. The potential of positron microprobe techniques will be discussed also.

  20. Update on the Argonne positron accumulator ring

    SciTech Connect

    Borland, M.

    1993-07-01

    The injector for the Advanced Photon Source incorporates a 450-MeV positron accumulator ring (PAR) to decrease the filling time with the 2-Hz synchrotron. In addition to accumulating positrons from the linac, the PAR damps the beam and reduces the bunch length. The PAR lattice has been redesigned to use zero-gradient dipoles, while retaining essentially the same damping partition. Extensive simulations have been performed to set tolerances that will give high capture efficiency, in spite of the large momentum spread of the incoming positron beam.

  1. Magnet innovations for linacs

    SciTech Connect

    Halbach, K.

    1986-06-01

    It is possible to produce large magnetic fields at the aperture of permanent magnet quadrupoles, even when the magnetic aperture is very small. That, combined with their compactness, makes permanent magnet quadrupoles very powerful components of small aperture linacs. Results will be presented about past and present work on both fixed and variable strength permanent magnets suitable for use in and around linacs.

  2. CSNS LINAC DESIGN

    SciTech Connect

    FU, S.; FANG, S.; WEI, J.

    2006-08-21

    China Spallation Neutron Source has been approved in principle by the Chinese government. CSNS can provide a beam power of 100kW on the target in the first phase, and then 200kW in the second phase. The accelerator complex of CSNS consists of an H- linac of 81MeV and a rapid cycling synchrotron of 1.6GeV at 25Hz repetition rate. In the second phase, the linac energy will be upgraded to 132MeV and the average current will be doubled. The linac has been designed, and some R&D studies have started under the support from Chinese Academy of Sciences. The linac comprises a H- ion source, an RFQ and a conventional DTL with EMQs. This paper will present our major design results and some progresses in the R&D of the linac.

  3. Admittance Test and Conceptual Study of a CW Positron Source for CEBAF

    SciTech Connect

    Golge, Serkan; Hyde, Charles E.; Freyberger, Arne

    2009-09-02

    A conceptual study of a Continuous Wave (CW) positron production is presented in this paper. The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLAB) operates with a CW electron beam with a well-defined emittance, time structure and energy spread. Positrons created via bremsstrahlung photons in a high-Z target emerge with a large emittance compared to incoming electron beam. An admittance study has been performed at CEBAF to estimate the maximum beam phase space area that can be transported in the LINAC and in the Arcs. A positron source is described utilizing the CEBAF injector electron beam, and directly injecting the positrons into the CEBAF LINAC.

  4. KEK-IMSS Slow Positron Facility

    NASA Astrophysics Data System (ADS)

    Hyodo, T.; Wada, K.; Yagishita, A.; Kosuge, T.; Saito, Y.; Kurihara, T.; Kikuchi, T.; Shirakawa, A.; Sanami, T.; Ikeda, M.; Ohsawa, S.; Kakihara, K.; Shidara, T.

    2011-12-01

    The Slow Positron Facility at the Institute of Material Structure Science (IMSS) of High Energy Accelerator Research Organization (KEK) is a user dedicated facility with an energy tunable (0.1 - 35 keV) slow positron beam produced by a dedicated 55MeV linac. The present beam line branches have been used for the positronium time-of-flight (Ps-TOF) measurements, the transmission positron microscope (TPM) and the photo-detachment of Ps negative ions (Ps-). During the year 2010, a reflection high-energy positron diffraction (RHEPD) measurement station is going to be installed. The slow positron generator (converter/ moderator) system will be modified to get a higher slow positron intensity, and a new user-friendly beam line power-supply control and vacuum monitoring system is being developed. Another plan for this year is the transfer of a 22Na-based slow positron beam from RIKEN. This machine will be used for the continuous slow positron beam applications and for the orientation training of those who are interested in beginning researches with a slow positron beam.

  5. Positron beam position measurement for a beam containing both positrons and electrons

    SciTech Connect

    Sereno, N.S.; Fuja, R.

    1996-08-01

    Positron beam position measurement for the Advanced Photon Source (APS) linac beam is affected by the presence of electrons that are also captured and accelerated along with the positrons. This paper presents a method of measuring positron position in a beam consisting of alternating bunches of positrons and electrons. The method is based on Fourier analysis of a stripline signal at the bunching and first harmonic frequencies. In the presence of a mixed species beam, a certain linear combination of bunching and first harmonic signals depends only on the position and charge of one specie of particle. A formula is derived for the stripline signal at all harmonics of the bunching frequency and is used to compute expected signal power at the bunching and first harmonic frequencies for typical electron and positron bunch charges. The stripline is calibrated by measuring the signal power content at the bunching and first harmonic frequencies for a single species beam. A circuit is presented that will be used with an APS positron linac stripline beam position monitor to detect the bunching and first harmonic signals for a beam of positrons and electrons.

  6. Review of induction LINACS

    SciTech Connect

    Faltens, A.; Keefe, D.

    1981-10-01

    There has been a recent upsurge of activity in the field of induction linacs, with several new machines becoming operational and others in the design stages. The performance levels of electron machines have reached 10's of kiloamps of current and will soon reach 10's of MeV's of energy. Acceleration of ion current has been demonstrated, and the study of a 10 GeV heavy ion induction linac for ICF continues. The operating principles of induction linacs are reviewed with the emphasis on design choices which are important for increasing the maximum beam currents.

  7. SSC linac injector

    SciTech Connect

    Bhatia, T.S.; Guy, F.W.; Neuschaefer, G.H.; Pabst, M.; Schriber, S.O.; Stovall, J.E.; Wangler, T.P.; Wilson, M.T.; Worth, G.T.

    1988-01-01

    The parameters for the proposed SSC linac injector system are obtained from the established requirements of the low-energy booster (LEB). The first element of this injector system is a radio-frequency quadrupole (RFQ) that bunches the H/sup /minus// ions and accelerates these ion bunches to 2.5 MeV. With a suitable matching section, this beam is injected into a drift-tube linac (DTL), which takes the ions to 120 MeV. The final element is a coupled-cavity linac (CCL) designed to accelerate the H/sup /minus// ions to 600 MeV for injection into the LEB. The conceptual beam dynamics design for the various elements of this linac injector system are described. 4 refs., 5 figs., 4 tabs.

  8. Status of the fluorescent screens and image processing for the APS linac

    SciTech Connect

    Berg, W.; Ko, K.

    1993-11-01

    Ten fluorescent screens and cameras determine the relative position and image profile of the beam in both the electron and positron linacs at the Advanced Photon Source (APS). The timing techniques used to capture the beam image allow direct synchronization to the electron gun trigger to minimize timing uncertainties. This paper discusses the design and status of the APS linac fluorescent screen assemblies and imaging system.

  9. Advanced RF power sources for linacs

    SciTech Connect

    Wilson, P.B.

    1996-10-01

    In order to maintain a reasonable over-all length at high center-of-mass energy, the main linac of an electron-positron linear collider must operate at a high accelerating gradient. For copper (non-superconducting) accelerator structures, this implies a high peak power per unit length and a high peak power per RF source, assuming a limited number of discrete sources are used. To provide this power, a number of devices are currently under active development or conceptual consideration: conventional klystrons with multi-cavity output structures, gyroklystrons, magnicons, sheet-beam klystrons, multiple-beam klystrons and amplifiers based on the FEL principle. To enhance the peak power produced by an rf source, the SLED rf pulse compression scheme is currently in use on existing linacs, and new compression methods that produce a flatter output pulse are being considered for future linear colliders. This paper covers the present status and future outlook for the more important rf power sources and pulse compression systems. It should be noted that high gradient electron linacs have applications in addition to high-energy linear colliders; they can, for example, serve as compact injectors for FEL`s and storage rings.

  10. Progress in Induction Linacs

    SciTech Connect

    Caporaso, G J

    2000-09-27

    This presentation will be a broad survey of progress in induction technology over the past four years. Much work has been done on accelerators for hydrodynamic test radiography and other applications. Solid-state pulsers have been developed which can provide unprecedented flexibility and precision in pulse format and accelerating voltage for both ion and electron induction machines. Induction linacs can now be built which can operate with MHz repetition rates. Solid-state technology has also made possible the development of fast kickers for precision control of high current beams. New insulator technology has been developed which will improve conventional induction linacs in addition to enabling a new class of high gradient induction linacs.

  11. Positron Physics

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J.

    2003-01-01

    I will give a review of the history of low-energy positron physics, experimental and theoretical, concentrating on the type of work pioneered by John Humberston and the positronics group at University College. This subject became a legitimate subfield of atomic physics under the enthusiastic direction of the late Sir Harrie Massey, and it attracted a diverse following throughout the world. At first purely theoretical, the subject has now expanded to include high brightness beams of low-energy positrons, positronium beams, and, lately, experiments involving anti-hydrogen atoms. The theory requires a certain type of persistence in its practitioners, as well as an eagerness to try new mathematical and numerical techniques. I will conclude with a short summary of some of the most interesting recent advances.

  12. Recirculated and Energy Recovered Linacs

    SciTech Connect

    Geoffrey Krafft

    2003-05-01

    Linacs that are recirculated share many characteristics with ordinary linacs, including the ability to accelerate electron beams from an injector to high energy with relatively little (normalized) emittance growth and the ability to deliver ultrashort bunch duration pulses to users. When such linacs are energy recovered, the additional possibility of accelerating very high average beam current arises. Because this combination of beam properties is not possible from either a conventional linac, or from storage rings where emittance and pulse length are set by the equilibrium between radiation damping and quantum excitation of oscillations about the closed orbit, energy recovered linacs are being considered for an increasing variety of applications. These possibilities extend from high power free-electron lasers and recirculated linac light sources, to electron coolers for high energy colliders or actual electron-ion colliding- beam machines based on an energy recovered linac for the electrons.

  13. Space charge in proton linacs

    SciTech Connect

    Wangler, T.P.; Merrill, F.; Rybarcyk, L.; Ryne, R.

    1998-12-31

    There are at least two reasons for the interest in space-charge effects in proton linacs. First, it can be expected that there are some areas of commonality in the space-charge physics of linacs and circular machines. Second, a linac delivers the input beam to a circular machine, so understanding the linac physics helps to explain the limitations for the input beam quality to a ring. This presentation is divided into three parts. First, the authors discuss space-charge effects form the linac point of view. Second, they discuss practical methods of calculation of linac beam dynamics that include space-charge forces. Finally, they summarize the status of experimental studies of the beam performance in the LANSCE linac including space-charge effects.

  14. High intensity positron beam and angular correlation experiments at Livermore

    SciTech Connect

    Howell, R.H.; Rosenberg, I.J.; Meyer, P.; Fluss, M.J.

    1985-03-01

    A positron beam apparatus that produces a variable energy positron beam with sufficient intensity to perform new positron experiments in an ultrahigh vacuum environment has been installed at the Lawrence Livermore 100 MeV electron linac. We have installed two large area position sensitive gamma-ray detectors to measure angular correlations in two dimensions and a separate highly collimated detector to measure positronium energy distributions by time-of-flight velocity determination. Data from measurements on single crystals of Cu will be described.

  15. Superconducting linacs: some recent developments

    SciTech Connect

    Bollinger, L.M.

    1985-01-01

    The paper is a review of superconducting linacs that are of interest for heavy-ion acceleration. Most of the paper is concerned with energy boosters for projectiles from tandem electrostatic accelerators, the only application for which superconducting linacs are now used for heavy-ion acceleration. There is also a brief discussion of the concept of a superconducting injector linac being developed as a replacement of the tandem in a multi-stage acceleration system. Throughout, the emphasis is on the technology of the superconducting linac, including some attention to the relationships between resonator design parameters and accelerator performance characteristics. 21 refs., 14 figs., 3 tabs.

  16. Proton linac for hospital-based fast neutron therapy and radioisotope production

    SciTech Connect

    Lennox, A.J.; Hendrickson, F.R.; Swenson, D.A.; Winje, R.A.; Young, D.E.; Rush Univ., Chicago, IL; Science Applications International Corp., Princeton, NJ; Fermi National Accelerator Lab., Batavia, IL )

    1989-09-01

    Recent developments in linac technology have led to the design of a hospital-based proton linac for fast neutron therapy. The 180 microamp average current allows beam to be diverted for radioisotope production during treatments while maintaining an acceptable dose rate. During dedicated operation, dose rates greater than 280 neutron rads per minute are achievable at depth, DMAX = 1.6 cm with source to axis distance, SAD = 190 cm. Maximum machine energy is 70 MeV and several intermediate energies are available for optimizing production of isotopes for Positron Emission Tomography and other medical applications. The linac can be used to produce a horizontal or a gantry can be added to the downstream end of the linac for conventional patient positioning. The 70 MeV protons can also be used for proton therapy for ocular melanomas. 17 refs., 1 fig., 1 tab.

  17. Positron Injector Accelerator and RF System for the ILC

    SciTech Connect

    Wang, J.W.; Adolphsen, C.; Bharadwaj, V.; Bowden, G.; Jongewaard, E.; Li, Z.; Miller, R.; Sheppard, J.C.; /SLAC

    2007-03-28

    Due to the extremely high energy deposition from positrons, electrons, photons and neutrons behind the positron target, and because a solenoid is required to focus the large emittance positron beam, the 1.3 GHz preaccelerator has to use normal conducting structures up to energy of 400 MeV. There are many challenges in the design of the normal-conducting portion of the ILC positron injector system such as obtaining high positron yield with required emittance, achieving adequate cooling with the high RF and particle loss heating, and sustaining high accelerator gradients during millisecond-long pulses in a strong magnetic field. Considering issues of feasibility, reliability and cost savings for the ILC, the proposed design for the positron injector contains both standing-wave (SW) and traveling-wave (TW) L-band accelerator structures. A short version of the new type of the SW section is under fabrication and testing. An updated status report is given. This paper also covers acceleration vs. deceleration for pre-accelerator sections, SW vs. TW structures, as well as longitudinal matching from target to linac and linac to damping ring.

  18. Energy matching of 1. 2 GeV positron beam to the SLC (Stanford Linear Collider) damping ring

    SciTech Connect

    Clendenin, J.E.; Helm, R.H.; Jobe, R.K.; Kulikov, A.; Sheppard, J.C.

    1989-08-01

    Positrons collected at the SLC positron source are transported over a 2-km path at 220 MeV to be reinjected into the linac for acceleration to 1.2 GeV, the energy of the emittance damping ring. Since the positron bunch length is a significant fraction of a cycle of the linac-accelerating RF, the energy spread at 1.2 GeV is considerably larger than the acceptance of the linac-to-ring (LTR) transport system. Making use of the large pathlength difference at the beginning of the LTR due to this energy spread, a standard SLAC 3-m accelerating section has been installed in the LTR to match the longitudinal phase space of the positron beam to the acceptance of the damping ring. The design of the matching system is described, and a comparison of operating results within simulations is presented. 5 refs., 4 figs., 1 tab.

  19. Compact LINAC for deuterons

    SciTech Connect

    Kurennoy, S S; O' Hara, J F; Rybarcyk, L J

    2008-01-01

    We are developing a compact deuteron-beam accelerator up to the deuteron energy of a few MeV based on room-temperature inter-digital H-mode (IH) accelerating structures with the transverse beam focusing using permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we show that IHPMQ structures provide very efficient and practical accelerators for light-ion beams of considerable currents at the beam velocities around a few percent of the speed of light. IH-structures with PMQ focusing following a short RFQ can also be beneficial in the front end of ion linacs.

  20. Energy Recovery Linacs

    SciTech Connect

    Nikolitsa Merminga

    2007-06-01

    The success and continuing progress of the three operating FELs based on Energy Recovery Linacs (ERLs), the Jefferson Lab IR FEL Upgrade, the Japan Atomic Energy Agency (JAEA) FEL, and the Novosibirsk High Power THz FEL, have inspired multiple future applications of ERLs, which include higher power FELs, synchrotron radiation sources, electron cooling devices, and high luminosity electron-ion colliders. The benefits of using ERLs for these applications are presented. The key accelerator physics and technology challenges of realizing future ERL designs, and recent developments towards resolving these challenges are reviewed.

  1. New medical linacs

    NASA Astrophysics Data System (ADS)

    Schonberg, R. G.; Mishin, A. V.

    1997-02-01

    X-band linacs designed and manufactured by Schonberg Research Corporation that are currently used by two spin-off companies for radiation therapy systems. Accuray employs a basic 6 MeV design with 300 R/min nominal dose rate at 80 cm from a tungsten target. The designed stereoscopic radiosurgery system is known as the Cyberknife. The Cyberknife combines a treatment planning, imaging and treatment delivery features. The treatment delivery system enclosure incorporates an accelerator head, RF components, pulse transformer and electronics mounted on a robotic arm. Intraop Medical, Inc. has introduced a system for intraoperative radiation therapy (IORT) called Mobetron (Mobile Electron Beam Intraoperative Treatment System). Mobetron is based on a 12 MeV two section X-band linac also designed by Schonberg Research Corporation. The accelerator design permits smooth energy variation from 4 to 12 MeV, but will be used at 4 specific energies. A self-shielded concept is applied to the system design. It will be used in conventional operating rooms without added shielding.

  2. Optimization of SRF Linacs

    SciTech Connect

    Powers, Tom

    2013-09-01

    This work describes preliminary results of a new software tool that allows one to vary parameters and understand the effects on the optimized costs of construction plus 10 year operations of an SRF linac, the associated cryogenic facility, and controls, where operations includes the cost of the electrical utilities but not the labor or other costs. It derives from collaborative work done with staff from Accelerator Science and Technology Centre, Daresbury, UK several years ago while they were in the process of developing a conceptual design for the New Light Source project.[1] The initial goal was to convert a spread sheet format to a graphical interface to allow the ability to sweep different parameter sets. The tools also allow one to compare the cost of the different facets of the machine design and operations so as to better understand the tradeoffs. The work was first published in an ICFA Beam Dynamics News Letter.[2] More recent additions to the software include the ability to save and restore input parameters as well as to adjust the Qo versus E parameters in order to explore the potential costs savings associated with doing so. Additionally, program changes now allow one to model the costs associated with a linac that makes use of energy recovery mode of operation.

  3. Beam dynamics verification in linacs of linear colliders

    SciTech Connect

    Seeman, J.T.

    1989-01-01

    The SLAC two-mile linac has been upgraded to accelerate high current, low emittance electron and positron beams to be used in the SLAC Linear Collider (SLC). After the upgrade was completed, extensive beam studies were made to verify that the design criteria have been met. These tests involved the measurement of emittance, beam phase space orientation, energy dispersion, trajectory oscillations, bunch length, energy spectrum and wakefields. The methods, the systems and the data cross checks are compared for the various measurements. Implications for the next linear collider are discussed. 12 refs., 13 figs., 2 tabs.

  4. Fast energy and energy spectrum feedback in the SLC Linac

    SciTech Connect

    Abrams, G.S.; Soderstrom, E.; Seeman, J.T.; Campisi, I.E.; Herrmannsfeldt, W.; Lee, M.; Petersen, A.; Phinney, N.; Ross, M.; Thompson, K.

    1987-01-01

    The energies and energy spectra of the positron and electron beams emerging from the SLC Linac must be carefully maintained so that the beams can be transported through the Arcs to the Final Focus without phase space dilution and also to specify the collision energy. A fastback system has been designed and constructed to control these parameters. The energies and energy spectra are measured nondestructively using position monitors and synchrotron radiation width monitors. The controls consist of rf phases in the Damping Rings, SLED timing, and rf amplitude. Theoretical aspects of the feedback process, algorithms, and operational experience are discussed.

  5. The APS transfer line from linac to injector synchrotron

    SciTech Connect

    Koul, R.K.; Crosbie, E.

    1991-03-01

    This note describes the low-energy-transfer-line designed for the APS. The low energy transfer line constitutes two transport lines. One of these lines runs from linac to the positron accumulator ring, also called ``PAR``, and is 23.7138 m long. The second part of the low energy transport line runs from the ``PAR`` to the injector synchrtoron and is about 30.919 m long. The above length includes two quadrupoles, a bend magnet and a septum magnet in the injector synchrotron.

  6. RF-windows used at the KEKB linac

    NASA Astrophysics Data System (ADS)

    Michizono, S.; Saito, Y.; Matsumoto, T.; Fukuda, S.; Anami, S.

    2001-01-01

    In the KEKB linac (8 GeV electrons and 3.5 GeV positrons), 58 pulsed klystrons (2856 MHz, 40 MW, 4 μs, 50 pps) are used for electron/positron acceleration. Alumina pill-box windows are installed in the klystrons and waveguides in order to isolate the vacuum from the atmosphere and to pass rf power. Breakdown of alumina ceramics is one of the most serious problems concerning stable operation. A temperature rise (Δ T) on a pill-box housing during rf operation is good for breakdown diagnostics and this has been measured periodically. The measured values are summarized statistically and broken windows are also analyzed.

  7. Beam-based alignment technique for the SLC (Stanford Linear Collider) linac

    SciTech Connect

    Adolphsen, C.E.; Lavine, T.L.; Atwood, W.B.; Himel, T.M.; Lee, M.J.; Mattison, T.S.; Pitthan, R.; Seeman, J.T.; Williams, S.H.; Trilling, G.H.

    1989-03-01

    Misalignment of quadrupole magnets and beam position monitors (BPMs) in the linac of the SLAC Linear Collider (SLC) cause the electron and positron beams to be steered off-center in the disk-loaded waveguide accelerator structures. Off-center beams produce wakefields which limit the SLC performance at high beam intensities by causing emittance growth. Here, we present a general method for simultaneously determining quadrupole magnet and BPM offsets using beam trajectory measurements. Results from the application of the method to the SLC linac are described. The alignment precision achieved is approximately 100 ..mu..m, which is significantly better than that obtained using optical surveying techniques. 2 refs., 4 figs.

  8. Low-charge-state linac

    SciTech Connect

    Shepard, K.W.; Kim, J.W.

    1995-08-01

    A design is being developed for a low-charge-state linac suitable for injecting ATLAS with a low-charge-state, radioactive beam. Initial work indicates that the existing ATLAS interdigital superconducting accelerating structures, together with the superconducting quadrupole transverse focussing element discussed above, provides a basis for a high-performance low-charge-state linac. The initial 2 or 3 MV of such a linac could be based on a normally-conducting, low-frequency RFQ, possibly combined with 24-MHz superconducting interdigital structures. Beam dynamics studies of the whole low-charge-state post-accelerator section were carried out in early FY 1995.

  9. Construction and commissioning of the positron accumulator ring for the APS

    SciTech Connect

    Borland, M.

    1994-12-31

    The injector for the Advanced Photon Source (APS) incorporates a 450-MeV positron accumulator ring (PAR) to accumulate and damp positrons from the 60Hz linac during each cycle of the 2-Hz synchrotron. An overview of PAR hardware is presented. Commissioning of the PAR is well underway using electrons. Studies have produced a modified lattice model using three free parameters that agrees well with measurements. Principle problems are high leakage fields from the septum and ion trapping.

  10. Space charge in proton linacs

    SciTech Connect

    Wangler, T. P.; Merrill, F.; Rybarcyk, L.; Ryne, R.

    1998-11-05

    Space charge effects on beam dynamics in linear accelerators are discussed. Practical linac beam dynamics calculation methods which include space charge effects are discussed. Also, the status of beam performance experiments including space charge studies are summarized.

  11. SLAC Linac Preparations for FACET

    SciTech Connect

    Erickson, R.; Bentson, L.; Kharakh, D.; Owens, A.; Schuh, P.; Seeman, J.; Sheppard, J.C.; Stanek, M.; Wittmer, W.; Yocky, G.; Wienands, U.; /SLAC

    2011-02-07

    The SLAC 3km linear electron accelerator has been cut at the two-thirds point to provide beams to two independent programs. The last third provides the electron beam for the Linac Coherent Light Source (LCLS), leaving the first two-thirds available for FACET, the new experimental facility for accelerator science and test beams. In this paper, we describe this separation and projects to prepare the linac for the FACET experimental program.

  12. Induction Linac Pulsers

    SciTech Connect

    Faltens, Andris

    2011-01-07

    The pulsers used in most of the induction linacs evolved from the very large body of work that was done in the U.S. and Great Britain during the development of the pulsed magnetron for radar. The radar modulators started at {approx}100 kW and reached >10 MW by 1945. A typical pulse length was 1 {mu}s at a repetition rate of 1,000 pps. A very comprehensive account of the modulator development is Pulse Generators by Lebacqz and Glasoe, one of the Radiation Laboratory Series. There are many permutations of possible modulators, two of the choices being tube type and line type. In earlier notes I wrote that technically the vacuum tube pulser met all of our induction linac needs, in the sense that a number of tubes, in series and parallel if required, could produce our pulses, regulate their voltage, be useable in feed-forward correctors, and provide a low source impedance. At a lower speed, an FET array is similar, and we have obtained and tested a large array capable of >10 MW switching. A modulator with an electronically controlled output only needs a capacitor for energy storage and in a switched mode can transfer the energy from the capacitor to the load at high efficiency. Driving a full size Astron induction core and a simulated resistive 'beam load' we achieved >50% efficiency. These electronically controlled output pulses can produce the pulses we desire but are not used because of their high cost. The second choice, the line type pulser, visually comprises a closing switch and a distributed or a lumped element transmission line. The typical switch cannot open or stop conducting after the desired pulse has been produced, and consequently all of the initially stored energy is dissipated. This approximately halves the efficiency, and the original cost estimating program LIACEP used this factor of two, even though our circuits are usually worse, and even though our inveterate optimists often omit it. The 'missing' energy is that which is reflected back into the

  13. Simulations of Jitter Coupling due to Wakefields in the FACET Linac

    SciTech Connect

    Molloy, Stephen

    2009-10-30

    Facilities for Accelerator Science and Experimental Test Beams (FACET) is a proposed facility at SLAC that would use the initial two-thirds of the linac to transport e{sup +} and e{sup -} beams to an experimental region. A principal use of this facility is to identify the optimum method for accelerating positrons in a beam driven plasma wakefield accelerator. To study this, a positron bunch, followed an RF-cycle later by an electron bunch, will be accelerated to an asymmetric chicane designed to move the positrons behind the electrons, and then on to the plasma wakefield test stand. A major focus of study was the coupling of jitter of the positron bunch to the electron bunch via linac wakes. Lucretia is a Matlab toolbox for the simulation of electron beam transport systems, capable of multi-bunch tracking and wakefield calculations. With the exception of the lack of support for tracking of electrons and positrons within a single bunch train, it was well suited to the jitter coupling studies. This paper describes the jitter studies, including modifications made to Lucretia to correctly simulate tracking of mixed-species bunch trains through a lattice of magnetic elements and EM wakes.

  14. Multibunch energy and spectrum control in the SLC High Energy Linac

    SciTech Connect

    Seeman, J.T.; Decker, F.J.; Jobe, R.K.; Hsu, I.

    1991-05-01

    Three intense bunches (two electron and one positron) are accelerated on each rf pulse in the SLC Linac. Careful control of the energy and energy spectrum of each bunch is needed to provide acceptable beams at the collision point and the positron productive target. The required rf amplitude, timing, and phase adjustments can be calculated and adjusted in real time to correct for changing conditions. BNS damping and energy feedback systems reduce the available reserve energy, which is limited. Observations and stability of actual beams are reviewed. Implications for a future collider are discussed. 10 refs., 3 figs., 1 tab.

  15. Lattice Design for the LHEC Recirculating Linac

    SciTech Connect

    Sun, Yipeng; Eide, Anders; Zimmermann, Frank; Adolphsen, Chris; /SLAC

    2011-05-20

    In this paper, we present a lattice design for the Large Hadron Electron Collider (LHeC) recirculating linac. The recirculating linac consists of one roughly 3-km long linac hosting superconducting RF (SRF) accelerating cavities, two arcs and one transfer line for the recirculation. In two passes through a pulsed SRF linac the electron beam can get a maximum energy of 140 GeV. Alternatively, in the Energy Recovery Linac (ERL) option the beam passes through a CW linac four times (two passes for acceleration and two for deceleration) for a maximum energy of 60 GeV.

  16. Transverse Beam Emittance Measurements of a 16 MeV Linac at the Idaho Accelerator Center

    SciTech Connect

    S. Setiniyaz, T.A. Forest, K. Chouffani, Y. Kim, A. Freyberger

    2012-07-01

    A beam emittance measurement of the 16 MeV S-band High Repetition Rate Linac (HRRL) was performed at Idaho State University's Idaho Accelerator Center (IAC). The HRRL linac structure was upgraded beyond the capabilities of a typical medical linac so it can achieve a repetition rate of 1 kHz. Measurements of the HRRL transverse beam emittance are underway that will be used to optimize the production of positrons using HRRL's intense electron beam on a tungsten converter. In this paper, we describe a beam imaging system using on an OTR screen and a digital CCD camera, a MATLAB tool to extract beamsize and emittance, detailed measurement procedures, and the measured transverse emittances for an arbitrary beam energy of 15 MeV.

  17. PILAC: A Pion Linac facility for 1-GeV pion physics at LAMPF

    SciTech Connect

    Thiessen, H.A.

    1991-12-31

    A design study for a Pion Linac (PILAC) at LAMPF is underway at Los Alamos. We present here a reference design for a system of pion source, linac, and high-resolution beam line and spectrometer that will provide 10{sup 9} pions per second on target and 200-keV resolution for the ({pi} {sup +}, K{sup +}) reaction at 0.92 GeV. A general-purpose beam line that delivers both positive and negative pions in the energy range 0.4--1.1 GeV is included, thus opening up the possibility of a broad experimental program as is discussed in this report. A kicker-based beam sharing system allows delivery of beam to both beamlines simultaneously with independent sign and energy control. Because the pion linac acts like and rf particle separator, all beams produced by PILAC will be free of electron (or positron) and proton contamination.

  18. LINACS FOR FUTURE MUON FACILITIES

    SciTech Connect

    Slawomir Bogacz, Rolland Johnson

    2008-10-01

    Future Muon Colliders (MC) and Neutrino Factories (NF) based on muon storage rings will require innovative linacs to: produce the muons, cool them, compress longi-tudinally and ‘shape’ them into a beam and finally to rap-idly accelerate them to multi-GeV (NF) and TeV (MC) energies. Each of these four linac applications has new requirements and opportunities that follow from the na-ture of the muon in that it has a short lifetime (τ = 2.2 μsec) in its own rest frame, it is produced in a tertiary process into a large emittance, and its electron, photon, and neutrino decay products can be more than an annoy-ance. As an example, for optimum performance, the linac repetition rates should scale inversely with the laboratory lifetime of the muon in its storage ring, something as high as 1 kHz for a 40 GeV Neutrino Factory or as low as 20 Hz for a 5 TeV Muon Collider. A superconducting 8 GeV Linac capable of CW operation is being studied as a ver-satile option for muon production [1] for colliders, facto-ries, and muon beams for diverse purposes. A linac filled with high pressure hydrogen gas and imbedded in strong magnetic fields has been proposed to rapidly cool muon beams [2]. Recirculating Linear Accelerators (RLA) are possible because muons do not generate significant syn-chrotron radiation even at extremely high energy and in strong magnetic fields. We will describe the present status of linacs for muon applications; in particular the longitu-dinal bunch compression in a single pass linac and multi-pass acceleration in the RLA, especially the optics and technical requirements for RLA designs, using supercon-ducting RF cavities capable of simultaneous acceleration of both μ+ and μ- species, with pulsed linac quadrupoles to allow the maximum number of passes. The design will include the optics for the multi-pass linac and droplet-shaped return arcs.

  19. Studies of slow-positron production using low-energy primary electron beams.

    SciTech Connect

    Lessner, E.

    1999-04-20

    Slow-positron beams produced from negative-work-function solid-state moderators have found numerous applications in condensed matter physics. There are potential advantages in using low-energy primary electron beams for positron production, including reduced radiation damage to single-crystal moderators and reduced activation of nearby components. We present numerical calculations of positron yields and other beam parameters for various target-moderator configurations using the Argonne Wakefield Accelerator (AWA) [1] and Advanced Photon Source (APS) [2] electron linacs [3] as examples of sources for the primary electron beams. The status of experiments at these facilities is reviewed.

  20. High-Intensity Continuous Wave Slow Positron Source at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Golge, Serkan; Vlahovic, Branislav; Wojtsekhowski, Bogdan

    2013-04-01

    We present a novel concept of an electron linac-based slow positron source with projected intensity on the order of 10^10 slow e^+/s. The key components of this concept are a Continuous Wave (CW) electron beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of positrons into a field-free area through a magnetic field terminator plug for moderation in a solid Neon moderator. The feasibility calculations were completed in the framework of GEANT4 simulation and OPERA-3D magnetic field calculation code.

  1. Commissioning of the LCLS LINAC

    SciTech Connect

    Loos, H.; Akre, R.; Brachmann, A.; Decker, F.-J.; Ding, Y.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Limborg-Deprey, C.; Miahnahri, A.; Molloy, S.; Nuhn, H.-D.; Turner, J.; Welch, J.; White, W.; Wu, J.; /SLAC /Stanford U., Appl. Phys. Dept.

    2010-06-11

    The Linac Coherent Light Source (LCLS) X-ray free electron laser project is currently under construction at the Stanford Linear Accelerator Center (SLAC). A new injector and upgrades to the existing accelerator were installed in two phases in 2006 and 2007. We report on the commissioning of the injector, the two new bunch compressors at 250MeV and 4.3 GeV, and transverse and longitudinal beam diagnostics up to the end of the existing linac at 13.6 GeV. The commissioning of the new transfer line from the end of the linac to the undulator is scheduled to start in November 2008 and for the undulator in March 2009 with first light to be expected in July 2009.

  2. IMPACT simulation and the SNS linac beam

    SciTech Connect

    Zhang, Y.; Qiang, J.

    2008-09-03

    Multi-particle tracking simulations for the SNS linac beam dynamics studies are performed with the IMPACT code. Beam measurement results are compared with the computer simulations, including beam longitudinal halo and beam losses in the superconducting linac, transverse beam Courant-Snyder parameters and the longitudinal beam emittance in the linac. In most cases, the simulations show good agreement with the measured results.

  3. Linac Energy Management for LCLS

    SciTech Connect

    Chu, Chungming; Iverson, Richard; Krejcik, Patrick; Rogind, Deborah; White, Greg; Woodley, Mark; /SLAC

    2012-07-05

    Linac Energy Management (LEM) is a control system program that scales magnet field set-point settings following a change in beam energy. LEM is necessary because changes in the number, phase, and amplitude of the active klystrons change the beam's rigidity, and therefore, to maintain constant optics, one has to change focusing gradients and bend fields accordingly. This paper describes the basic process, the control system application programs we developed for LEM, and some of the implementation lessons learned at the Linac Coherent Light Source (LCLS).

  4. Intrabeam stripping in H- Linacs

    SciTech Connect

    Lebedev, V.; Solyak, N.; Ostigy, J.-F.; Alexandrov, A.; Shishlo, A.; /Oak Ridge

    2010-09-01

    A beam loss in the superconducting part of the SNS linac has been observed during its commissioning and operation. Although the loss does not prevent the SNS high power operation, it results in an almost uniform irradiation of linac components and increased radiation levels in the tunnel. Multi-particle tracking could neither account for the magnitude of the observed loss nor its dependence on machine parameters. It was recently found that the loss is consistent with the intrabeam particle collisions resulting in stripping of H{sup -} ions. The paper describes experimental observations and corresponding analytical estimates of the intrabeam stripping.

  5. Multiple single-board-computer system for the KEK positron generator control

    NASA Astrophysics Data System (ADS)

    Nakahara, Kazuo; Abe, Isamu; Enomoto, Atsushi; Otake, Yuji; Urano, Takao

    1986-06-01

    The KEK positron generator is controlled by means of a distributed microprocessor network. The control system is composed of three kinds of equipment: device controllers for the linac equipment, operation management stations and a communication network. Individual linac equipment has its own microprocessor-based controller. A multiple single board computer (SBC) system is used for communication control and for equipment surveillance; it has a database containing communication and linac equipment status information. The linac operation management that should be the most soft part in the control system, is separated from the multiple SBC system and is carried out by work-stations. The principle that every processor executes only one task is maintained throughout the control system. This made the software architecture very simple.

  6. The Linac Coherent Light Source

    SciTech Connect

    White, William E.; Robert, Aymeric; Dunne, Mike

    2015-04-21

    The Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory was the first hard X-ray free-electron laser (FEL) to operate as a user facility. After five years of operation, LCLS is now a mature FEL user facility. Our personal views about opportunities and challenges inherent to these unique light sources are discussed.

  7. The Linac Coherent Light Source

    PubMed Central

    White, William E.; Robert, Aymeric; Dunne, Mike

    2015-01-01

    The Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory was the first hard X-ray free-electron laser (FEL) to operate as a user facility. After five years of operation, LCLS is now a mature FEL user facility. Our personal views about opportunities and challenges inherent to these unique light sources are discussed. PMID:25931055

  8. Space charge in proton linacs

    SciTech Connect

    Wangler, T.P.; Merrill, F.; Rybarcyk, L.; Ryne, R.

    1998-11-01

    Space charge effects on beam dynamics in linear accelerators are discussed. Practical linac beam dynamics calculation methods which include space charge effects are discussed. Also, the status of beam performance experiments including space charge studies are summarized. {copyright} {ital 1998 American Institute of Physics.}

  9. The Linac Coherent Light Source

    DOE PAGESBeta

    White, William E.; Robert, Aymeric; Dunne, Mike

    2015-05-01

    The Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory was the first hard X-ray free-electron laser (FEL) to operate as a user facility. After five years of operation, LCLS is now a mature FEL user facility. Our personal views about opportunities and challenges inherent to these unique light sources are discussed.

  10. PROGRESS IN DESIGN OF THE SNS LINAC

    SciTech Connect

    R. HARDEKOPF

    2000-11-01

    The Spallation Neutron Source (SNS) is a six-laboratory collaboration to build an intense pulsed neutron facility at Oak Ridge, TN. The linac design has evolved from the conceptual design presented in 1997 to achieve higher initial performance and to incorporate desirable upgrade features. The linac will initially produce 2-MW beam power using a combination of radio-frequency quadruple (RFQ) linac, drift-tube linac (DTL), coupled-cavity linac (CCL), and superconducting-cavity linac (SCL). Designs of each of these elements support the high peak intensity and high quality beam required for injection into the SNS accumulator ring. This paper will trace the evolution of the linac design, the cost and performance factors that drove architecture decisions, and the progress made in the R&D program.

  11. Positron emission tomography.

    PubMed

    Hoffman, E J; Phelps, M E

    1979-01-01

    Conventional nuclear imaging techniques utilizing lead collimation rely on radioactive tracers with little role in human physiology. The principles of imaging based on coincidence detection of the annihilation radiation produced in positron decay indicate that this mode of detection is uniquely suited for use in emission computed tomography. The only gamma-ray-emitting isotopes of carbon, nitrogen, and oxygen are positron emitters, which yield energies too high for conventional imaging techniques. Thus development of positron emitters in nuclear medicine imaging would make possible the use of a new class of physiologically active, positron-emitting radiopharmaceuticals. The application of these principles is described in the use of a physiologically active compound labeled with a positron emitter and positron-emission computed tomography to measure the local cerebral metabolic rate in humans. PMID:440173

  12. Positron-rubidium scattering

    NASA Technical Reports Server (NTRS)

    Mceachran, R. P.; Horbatsch, M.; Stauffer, A. D.

    1990-01-01

    A 5-state close-coupling calculation (5s-5p-4d-6s-6p) was carried out for positron-Rb scattering in the energy range 3.7 to 28.0 eV. In contrast to the results of similar close-coupling calculations for positron-Na and positron-K scattering the (effective) total integrated cross section has an energy dependence which is contrary to recent experimental measurements.

  13. F-18 production with the TOP linac injector

    NASA Astrophysics Data System (ADS)

    Cianfarani, Cesidio; Cisbani, Evaristo; Orlandi, Gianluca; Frullani, Salvatore; Picardi, Luigi; Ronsivalle, Concetta

    2006-06-01

    ENEA and ISS (Italian National Institute of Health), are collaborating to develop a dedicated proton medical accelerator, TOP (Oncological Therapy with Protons) linac, consisting of a sequence of three pulsed linear accelerators. The 7 MeV injector can be used in three operating modes: Protontherapy and Radiobiology Mode—injecting low current proton beam into the TOP linac accelerating sections; Radioisotope Mode—generating an intense proton beam (8-10 mA, 50-100 μs, 30-100 Hz) to produce the positron-emitting radionuclide F18 for PET analyses. In the high current mode, at the exit of the injector the beam is guided through a magnetic quadrupoles channel to a target composed by a thin chamber (0.5 mm thick and 1 in. diameter) containing water enriched with O18. Production yield as well as total activity similar to these achieved with higher energy cyclotrons have been obtained. Environmental doses measured give indications on the shielding required for operation under current radioprotection regulations. Improvements are foreseen to optimize the production yield, the useful beam current and to better characterize gamma and neutron dose rates in the different operational modes.

  14. High-intensity positron microprobe at Jefferson Lab

    SciTech Connect

    Golge, Serkan; Vlahovic, Branislav; Wojtsekhowski, Bogdan B.

    2014-06-19

    We present a conceptual design for a novel continuous wave electron-linac based high-intensity slow-positron production source with a projected intensity on the order of 1010 e+/s. Reaching this intensity in our design relies on the transport of positrons (T+ below 600 keV) from the electron-positron pair production converter target to a low-radiation and low-temperature area for moderation in a high-efficiency cryogenic rare gas moderator, solid Ne. The performance of the integrated beamline has been verified through computational studies. The computational results include Monte Carlo calculations of the optimized electron/positron beam energies, converter target thickness, synchronized raster system, transport of the beam from the converter target to the moderator, extraction of the beam from the channel, and moderation efficiency calculations. For the extraction of positrons from the magnetic channel a magnetic field terminator plug prototype has been built and experimental data on the effectiveness of this prototype are presented. The dissipation of the heat away from the converter target and radiation protection measures are also discussed.

  15. High-intensity positron microprobe at Jefferson Lab

    DOE PAGESBeta

    Golge, Serkan; Vlahovic, Branislav; Wojtsekhowski, Bogdan B.

    2014-06-19

    We present a conceptual design for a novel continuous wave electron-linac based high-intensity slow-positron production source with a projected intensity on the order of 1010 e+/s. Reaching this intensity in our design relies on the transport of positrons (T+ below 600 keV) from the electron-positron pair production converter target to a low-radiation and low-temperature area for moderation in a high-efficiency cryogenic rare gas moderator, solid Ne. The performance of the integrated beamline has been verified through computational studies. The computational results include Monte Carlo calculations of the optimized electron/positron beam energies, converter target thickness, synchronized raster system, transport of themore » beam from the converter target to the moderator, extraction of the beam from the channel, and moderation efficiency calculations. For the extraction of positrons from the magnetic channel a magnetic field terminator plug prototype has been built and experimental data on the effectiveness of this prototype are presented. The dissipation of the heat away from the converter target and radiation protection measures are also discussed.« less

  16. LFSC - Linac Feedback Simulation Code

    SciTech Connect

    Ivanov, Valentin; /Fermilab

    2008-05-01

    The computer program LFSC (<Linac Feedback Simulation Code>) is a numerical tool for simulation beam based feedback in high performance linacs. The code LFSC is based on the earlier version developed by a collective of authors at SLAC (L.Hendrickson, R. McEwen, T. Himel, H. Shoaee, S. Shah, P. Emma, P. Schultz) during 1990-2005. That code was successively used in simulation of SLC, TESLA, CLIC and NLC projects. It can simulate as pulse-to-pulse feedback on timescale corresponding to 5-100 Hz, as slower feedbacks, operating in the 0.1-1 Hz range in the Main Linac and Beam Delivery System. The code LFSC is running under Matlab for MS Windows operating system. It contains about 30,000 lines of source code in more than 260 subroutines. The code uses the LIAR ('Linear Accelerator Research code') for particle tracking under ground motion and technical noise perturbations. It uses the Guinea Pig code to simulate the luminosity performance. A set of input files includes the lattice description (XSIF format), and plane text files with numerical parameters, wake fields, ground motion data etc. The Matlab environment provides a flexible system for graphical output.

  17. Wakefields in SLAC linac collimators

    NASA Astrophysics Data System (ADS)

    Novokhatski, A.; Decker, F.-J.; Smith, H.; Sullivan, M.

    2014-12-01

    When a beam travels near collimator jaws, it gets an energy loss and a transverse kick due to the backreaction of the beam field diffracted from the jaws. The effect becomes very important for an intense short bunch when a tight collimation of the background beam halo is required. In the Linac Coherent Light Source at SLAC a collimation system is used to protect the undulators from radiation due to particles in the beam halo. The halo is most likely formed from gun dark current or dark current in some of the accelerating sections. However, collimators are also responsible for the generation of wake fields. The wake field effect from the collimators not only brings an additional energy jitter and change in the trajectory of the beam, but it also rotates the beam on the phase plane, which consequently leads to a degradation of the performance of the Free Electron Laser at the Linac Coherent Light Source. In this paper, we describe a model of the wake field radiation in the SLAC linac collimators. We use the results of a numerical simulation to illustrate the model. Based on the model, we derive simple formulas for the bunch energy loss and the average kick. We also present results from experimental measurements that confirm our model.

  18. ESS SC Linac Design Overview

    NASA Astrophysics Data System (ADS)

    Ferdinand, Robin

    2002-12-01

    The ESS project (European Spallation Source) aims to produce high power beams for condensed matter studies. One option consists in having both H+ and H- beams. They have to be accelerated and guided to the different spallation targets. Beam power up to 5 MW at 50 Hz plus 5 MW at 16.2/3 Hz, will be delivered on respectively the Short Pulse Target Station and the Long Pulse Target Station. Two 50 mA H- branches are funnelled with one 100 mA H+ beam at around 20 MeV. A chopper line between two RFQs and DTLs constitutes the H- front end. The H+ front end is composed of one RFQ and one DTL. After the funnel, the two species are transported through the same linac up to 1.334 GeV. This common part is composed of a SDTL and a CCL from 20 to 185 MeV and followed by a SuperConducting Linac (SCL) to reach the final energy. Up to recently (ESS Volume III 1996), a NC version of the linac had been extensively studied and constituted the reference option. However, given the fantastic progresses made on SC technology and the many potential advantages, a SC alternative was developed. We concentrate on this option.

  19. Positrons for linear colliders

    SciTech Connect

    Ecklund, S.

    1987-11-01

    The requirements of a positron source for a linear collider are briefly reviewed, followed by methods of positron production and production of photons by electromagnetic cascade showers. Cross sections for the electromagnetic cascade shower processes of positron-electron pair production and Compton scattering are compared. A program used for Monte Carlo analysis of electromagnetic cascades is briefly discussed, and positron distributions obtained from several runs of the program are discussed. Photons from synchrotron radiation and from channeling are also mentioned briefly, as well as positron collection, transverse focusing techniques, and longitudinal capture. Computer ray tracing is then briefly discussed, followed by space-charge effects and thermal heating and stress due to showers. (LEW)

  20. High beam current shut-off systems in the APS linac and low energy transfer line

    SciTech Connect

    Wang, X.; Knott, M.; Lumpkin, A.

    1994-11-01

    Two independent high beam current shut-off current monitoring systems (BESOCM) have been installed in the APS linac and the low energy transport line to provide personnel safety protection in the event of acceleration of excessive beam currents. Beam current is monitored by a fast current transformer (FCT) and fully redundant supervisory circuits connected to the Access Control Interlock System (ACIS) for beam intensity related shutdowns of the linac. One FCT is located at the end of the positron linac and the other in the low energy transport line, which directs beam to the positron accumulator ring (PAR). To ensure a high degree of reliability, both systems employ a continuous self-checking function, which injects a test pulse to a single-turn test winding after each ``real`` beam pulse to verify that the system is fully functional. The system is designed to be fail-safe for all possible system faults, such as loss of power, open or shorted signal or test cables, loss of external trigger, malfunction of gated integrator, etc. The system has been successfully commissioned and is now a reliable part of the total ACIS.

  1. BEAM DYNAMICS ISSUES IN THE SNS LINAC

    SciTech Connect

    Shishlo, Andrei P

    2011-01-01

    A review of the Spallation Neutron Source (SNS) linac beam dynamics is presented. It describes transverse and longitudinal beam optics, losses, activation, and comparison between the initial design and the existing accelerator. The SNS linac consists of normal conducting and superconducting parts. The peculiarities in operations with the superconducting part of the SNS linac (SCL), estimations of total losses in SCL, the possible mechanisms of these losses, and the progress in the transverse matching are discussed.

  2. Status of the Linac Coherent Light Source

    SciTech Connect

    Galayda, John N.; /SLAC

    2011-11-04

    The Linac Coherent Light Source (LCLS) is a free electron laser facility in construction at Stanford Linear Accelerator Center. It is designed to operate in the wavelength range 0.15-1.5 nanometers. At the time of this conference, civil construction of new tunnels and buildings is complete, the necessary modifications to the SLAC linac are complete, and the undulator system and x-ray optics/diagnostics are being installed. The electron gun, 135 MeV injector linac and 250 MeV bunch compressor were commissioned in 2007. Accelerator commissioning activities are presently devoted to the achievement of performance goals for the completed 14 GeV linac.

  3. Positron binding to molecules

    NASA Astrophysics Data System (ADS)

    Danielson, J. R.

    2011-05-01

    While there is theoretical evidence that positrons can bind to atoms, calculations for molecules are much less precise. Unfortunately, there have been no measurements of positron-atom binding, due primarily to the difficulty in forming positron-atom bound states in two-body collisions. In contrast, positrons attach to molecules via Feshbach resonances (VFR) in which a vibrational mode absorbs the excess energy. Using a high-resolution positron beam, this VFR process has been studied to measure binding energies for more than 40 molecules. New measurements will be described in two areas: positron binding to relatively simple molecules, for which theoretical calculations appear to be possible; and positron binding to molecules with large permanent dipole moments, which can be compared to analogous, weakly bound electron-molecule (negative-ion) states. Binding energies range from 75 meV for CS2 (no dipole moment) to 180 meV for acetonitrile (CH3CN). Other species studied include aldehydes and ketones, which have permanent dipole moments in the range 2.5 - 3.0 debye. The measured binding energies are surprisingly large (by a factor of 10 to 100) compared to those for the analogous negative ions, and these differences will be discussed. New theoretical calculations for positron-molecule binding are in progress, and a recent result for acetonitrile will be discussed. This ability to compare theory and experiment represents a significant step in attempts to understand positron binding to matter. In collaboration with A. C. L. Jones, J. J. Gosselin, and C. M. Surko, and supported by NSF grant PHY 07-55809.

  4. Main linac lattice design and optimization for Ecm = 1 TeV CLIC

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Wei; Schulte, Daniel; Gao, Jie

    2014-06-01

    The Compact Linear Collider (CLIC) is a future e+e- linear collider. The CLIC study concentrated on a design of center-of-mass energy of 3 TeV and demonstrated the feasibility of the technology. However, the physics also demands lower energy collision. To satisfy this, CLIC can be built in stages. The actual stages will depend on LHC results. Some specific scenarios of staged constructions have been shown in CLIC Concept Design Report (CDR). In this paper, we concentrate on the main linac lattice design for Ecm = 1 TeV CLIC aiming to upgrade from Ecm = 500 GeV CLIC and then to Ecm = 3 TeV one. This main linac accelerates the electron or positron beam from 9 GeV to 500 GeV. A primary lattice design based on the 3 TeV CLIC main linac design and its optimization based on the beam dynamics study will be presented. As we use the same design principles as 3TeV CLIC main linac, this optimization is basically identical to the 3 TeV one. All the simulations results are obtained using the tracking code PLACET.

  5. A low-neutron background slow-positron source.

    SciTech Connect

    White, M. M.

    1998-10-09

    The addition of a thermionic rf gun [1] and a photocathode rf gun will allow the Advanced Photon Source (APS) linear accelerator (linac) [2] [3] to become a free-electron laser (FEL) driver [4]. As the FEL project progresses, the existing high-charge DC thermionic gun will no longer be critical to APS operation and could be used to generate high-energy or low-energy electrons to drive a slow-positron source. We investigated possibilities to create a useful low-energy source that could operate semi-independently and would have a low neutron background.

  6. Recent studies of dispersion matched steering for the ILC bunch compressor and main linac

    SciTech Connect

    Lebrun, Paul L.G.; Michelotti, Leo P.; Ostiguy, Jean-Francois; /Fermilab

    2007-06-01

    The Dispersion Matched Steering (DMS) method is studied in detail in the context of a curved main linac. In the absence of cavity tilts (rotations in the YZ plane), DMS provides a unique and stable solution with negligible emittance growth. If cavity tilts are about 300 {micro}rad, the algorithm is not very robust. The emittance growth through the entire linac for positrons is about 5 nm, if the system is strictly static and statistical averaging can be used to improve beam position measurements. This growth is mostly eliminated if the dispersion and its derivative at injection can be adjusted. If anticipated ground motion, beam and klystron jitter, beam position measurement resolution are introduced (i.e. dynamical case), the emittance preservation goal is currently not achieved by DMS alone. Mitigation strategies are outlined.

  7. PILAC: A pion linac facility for 1-GeV pion physics at LAMPF

    SciTech Connect

    Thiessen, H.A.

    1991-01-01

    A design study or a Pion Linac (PILAC) at LAMPF is underway at Los Alamos. We present here a reference design for a system of pion sources, linac, and high-resolution beam line and spectrometer that will provide 10{sup 9} pions per second on target and 200-keV resolution for the ({pi}{sup +}, K{sup +}) reaction at 0.92 GeV. A general-purpose beam line that delivers both positive and negative pions in the energy range 0.4--1.1 GeV is included, thus opening up the possibility of a broad experimental program as is discussed in this report. A kicker-based beam sharing system allows delivery of beam to both beamlines simultaneously with independent sign and energy control. Because the pionlinac acts like an rf particle separator, all beams produced by PILAC will be free of electron (or positron) and proton contamination. 4 refs., 6 figs.

  8. Beam breakup in superconducting recirculating linacs

    SciTech Connect

    Joseph J. Bisognano

    1988-05-01

    The performance and operational flexibility of superconducting recirculating linacs can be limited by a variety of collective phenomena which are grouped under the name beam breakup. In this note the various beam breakup phenomena found in recirculating superconducting radio frequency linacs are described and appraised relative to beam performance.

  9. SLS linac diagnostics—commissioning results

    NASA Astrophysics Data System (ADS)

    Dach, M.; Dehler, M.; Jaggi, A.; Kramert, R.; Pedrozzi, P.; Schlott, V.; Streun, A.

    2000-11-01

    The paper presents the electron beam diagnostics along the 100 MeV pre-injector Linac for the Swiss Light Source (SLS). The concept of the different diagnostic monitors for current and current related measurements, optical measurements and beam position measurements are briefly described. Commissioning results of the pre-injector Linac are presented.

  10. Induction linacs and pulsed power

    SciTech Connect

    Caporaso, G.J.

    1995-07-11

    Progress in electronic power conversion technology is making possible a new class of induction linacs that can operate at extremely high repetition rates. Advances in insulator technology, pulse forming line design and switching may also lead to a new type of high current accelerator with accelerating gradients at least an order of magnitude greater than those attainable today. The evolution of the induction accelerator pulsed power system will be discussed along with some details of these emerging technologies which are at the frontiers of accelerator technology.

  11. Advanced positron sources

    NASA Astrophysics Data System (ADS)

    Variola, A.

    2014-03-01

    Positron sources are a critical system for the future lepton colliders projects. Due to the large beam emittance at the production and the limitation given by the target heating and mechanical stress, the main collider parameters fixing the luminosity are constrained by the e+ sources. In this context also the damping ring design boundary conditions and the final performance are given by the injected positron beam. At present different schemes are being taken into account in order to increase the production and the capture yield of the positron sources, to reduce the impact of the deposited energy in the converter target and to increase the injection efficiency in the damping ring. The final results have a strong impact not only on the collider performance but also on its cost optimization. After a short introduction illustrating their fundamental role, the basic positron source scheme and the performance of the existing sources will be illustrated. The main innovative designs for the future colliders advanced sources will be reviewed and the different developed technologies presented. Finally the positrons-plasma R&D experiments and the futuristic proposals for positron sources will reviewed.

  12. Positrons from supernovae

    NASA Technical Reports Server (NTRS)

    Chan, Kai-Wing; Lingenfelter, Richard E.

    1993-01-01

    Positrons are produced in the ejecta of supernovae by the decay of nucleosynthetic Co-56, Ti-44, and Al-26. We calculate the probability that these positrons can survive without annihilating in the supernova ejecta, and we show that enough of these positrons should escape into the interstellar medium to account for the observed diffuse Galactic annihilation radiation. The surviving positrons are carried by the expanding ejecta into the interstellar medium where their annihilation lifetime of 10 exp 5 - 10 exp 6 yr is much longer than the average supernovae occurrence time of about 100 yr. Thus, annihilating positrons from thousands of supernovae throughout the Galaxy produce a steady diffuse flux of annihilation radiation. We further show that combining the calculated positron survival fractions and nucleosynthetic yields for current supernova models with the estimated supernova rates and the observed flux of diffuse Galactic annihilation radiation suggests that the present Galactic rate of Fe-56 nucleosynthesis is about 0.8 +/- 0.6 solar mass per 100 yr.

  13. The DARHT Phase 2 Linac

    NASA Astrophysics Data System (ADS)

    Rutkowski, Henry

    The second phase accelerator for the Dual Axis Hydrodynamic Test facility (DARHT) is designed to provide an electron beam pulse that is 2 microsec long, 2kA, and 20 MeV in particle energy. The injector provides 3.2 MeV so that the linac need only provide 16.8 MeV. The linac is made with two types of induction accelerator cells. The first block of 8 cells have a 14 in. beam pipe compared to 10 in. in the remaining 80 cells. The other principal difference is that the first 8 cells have reduced volt-sec in their induction cores as a result of a larger diameter beam pipe. The cells are designed for very reliable high voltage operation. The insulator is Mycalex. Results from prototype tests are given including results from solenoid measurements. Each cell contains a solenoid for beam transport and a set of x-y correction coils to reduce corkscrew motion. Details of tests to determine RF mode impedances relevant to BBU generation are given. Blocks of cells are separated by "intercells" some of which contain transport solenoids. The intercells provide vacuum pumping stations as well. Issues of alignment and installation are discussed.

  14. A cryomodule for the RIA driver linac.

    SciTech Connect

    Fuerst, J. D.; Shepard, K. W.

    2002-10-25

    We present a cryomodule design for the superconducting linacs for the proposed Rare Isotope Accelerator Facility (RIA). This paper discusses the design of a cryomodule for all the drift-tube-loaded superconducting cavities required for the machine. The same basic design will be used for the low and medium velocity sections of the driver linac and also for sections of the radioactive ion beam (RIB) linac. Fundamental design choices such as separate vs. common beam and insulating vacuum spaces are driven by the clean fabrication techniques required for optimum cavity performance. The design can be adapted to a variety of cavity geometries.

  15. Beam dynamics design of a pion linac

    SciTech Connect

    Nath, S; Swain, G.; Garnett, R.; Wangler, T.P.

    1990-01-01

    We have conducted a study of a superconducting linac to accelerate pions produced at LAMPF from 400 or 500 MeV to 925 MeV kinetic energy. For such a linac, it is necessary to keep the machine as short as practical in order to minimize the loss of beam due to particle decay, and to tailor the beam to achieve the maximum flux within the desired momentum bite at the exit. The interplay of these and other considerations with the transverse and longitudinal beam dynamics is discussed, and is illustrated with the simulated performance of reference pion-linac designs.

  16. The SNS Superconducting Linac System

    SciTech Connect

    Claus Rode

    2001-07-01

    The SNS has adopted superconducting RF technology for the high-energy end of its linac. The design uses cavities of {beta} = 0.61 and 0.81 to span the energy region from 186 MeV up to a maximum of 1.3 GeV. Thirty-three of the lower {beta} cavities are contained in 11 cryomodules, and there could be as many as 21 additional cryomodules, each containing four of the higher {beta} cavities, to reach the maximum energy. The design uses a peak surface gradient of 35 MV/m. Each cavity will be driven by a 550 kW klystron. Cryomodules will be connected to the refrigerator by a pair of ''tee'' shape transfer lines. The refrigerator will produce 120 g/sec of refrigeration at 2.1 K, 15 g/sec of liquefaction at 4.5 K, and 8,300 W of 50 K shield refrigeration.

  17. Positron emission tomography

    NASA Astrophysics Data System (ADS)

    Yamamoto, Y. Lucas; Thompson, Christopher J.; Diksic, Mirko; Meyer, Ernest; Feindel, William H.

    One of the most exciting new technologies introduced in the last 10 yr is positron emission tomography (PET). PET provides quantitative, three-dimensional images for the study of specific biochemical and physiological processes in the human body. This approach is analogous to quantitative in-vivo autoradiography but has the added advantage of permitting non-invasive in vivo studies. PET scanning requires a small cyclotron to produce short-lived positron emitting isotopes such as oxygen-15, carbon-11, nitrogen-13 and fluorine-18. Proper radiochemical facilities and advanced computer equipment are also needed. Most important, PET requires a multidisciplinary scientific team of physicists, radiochemists, mathematicians, biochemists and physicians. This review analyzes the most recent trends in the imaging technology, radiochemistry, methodology and clinical applications of positron emission tomography.

  18. Alternative positron-target design for electron-positron colliders

    SciTech Connect

    Donahue, R.J. ); Nelson, W.R. )

    1991-04-01

    Current electron-positron linear colliders are limited in luminosity by the number of positrons which can be generated from targets presently used. This paper examines the possibility of using an alternate wire-target geometry for the production of positrons via an electron-induced electromagnetic cascade shower. 39 refs., 38 figs., 5 tabs.

  19. Injector linac for the MESA facility

    SciTech Connect

    Heine, R.

    2013-11-07

    In this paper we present several possible configurations of an injector linac for the upcoming Mainz Energy-recovering Superconducting Accelerator (MESA) [1] and discuss their suitability for the project.

  20. Intense positron beam at KEK

    NASA Astrophysics Data System (ADS)

    Kurihara, Toshikazu; Yagishita, Akira; Enomoto, Atsushi; Kobayashi, Hitoshi; Shidara, Tetsuo; Shirakawa, Akihiro; Nakahara, Kazuo; Saitou, Haruo; Inoue, Kouji; Nagashima, Yasuyuki; Hyodo, Toshio; Nagai, Yasuyoshi; Hasegawa, Masayuki; Inoue, Yoshi; Kogure, Yoshiaki; Doyama, Masao

    2000-08-01

    A positron beam is a useful probe for investigating the electronic states in solids, especially concerning the surface states. The advantage of utilizing positron beams is in their simpler interactions with matter, owing to the absence of any exchange forces, in contrast to the case of low-energy electrons. However, such studies as low-energy positron diffraction, positron microscopy and positronium (Ps) spectroscopy, which require high intensity slow-positron beams, are very limited due to the poor intensity obtained from a conventional radioactive-isotope-based positron source. In conventional laboratories, the slow-positron intensity is restricted to 10 6 e +/s due to the strength of the available radioactive source. An accelerator based slow-positron source is a good candidate for increasing the slow-positron intensity. One of the results using a high intensity pulsed positron beam is presented as a study of the origins of a Ps emitted from SiO 2. We also describe the two-dimensional angular correlation of annihilation radiation (2D-ACAR) measurement system with slow-positron beams and a positron microscope.

  1. Dark current model for ILC main linac

    SciTech Connect

    Solyak, N.; Romanov, G.; Mokhov, N.V.; Eidelman, Y.; Tam, Wai-Ming; /Indiana U.

    2008-06-01

    In the ILC Main Linac, the dark current electrons, generated in SRF cavity can be accelerated to hundreds of MeV before being kicked out by quadrupoles and thus will originate electromagnetic cascade showers in the surrounding materials. Some of the shower secondaries can return back into vacuum and be re-accelerated again. The preliminary results of simulation of the dark current generation in ILC cavity, its dynamics in linac are discussing in this paper.

  2. Scaling of Wakefield Effects in Recirculating Linacs

    SciTech Connect

    L. Merminga; G. R. Neil; B. C. Yunn; J. J. Bisognano

    2001-07-01

    Expressions for the induced energy spread and emittance degradation of a single bunch due to the longitudinal and transverse impedance of rf cavities at the end of a linac structure are presented. Scaling of the formulae with rf frequency is derived. Scaling of the threshold current for the multibunch, multipass beam breakup (BBU) instability in recirculating linacs with accelerator and beam parameters is also derived.

  3. Simulation of large acceptance LINAC for muons

    SciTech Connect

    Miyadera, H; Kurennoy, S; Jason, A J

    2010-01-01

    There has been a recent need for muon accelerators not only for future Neutrino Factories and Muon Colliders but also for other applications in industry and medical use. We carried out simulations on a large-acceptance muon linac with a new concept 'mixed buncher/acceleration'. The linac can accept pions/muons from a production target with large acceptance and accelerate muon without any beam cooling which makes the initial section of muon-linac system very compact. The linac has a high impact on Neutrino Factory and Muon Collider (NF/MC) scenario since the 300-m injector section can be replaced by the muon linac of only 10-m length. The current design of the linac consists of the following components: independent 805-MHz cavity structure with 6- or 8-cm-radius aperture window; injection of a broad range of pion/muon energies, 10-100 MeV, and acceleration to 150 - 200 MeV. Further acceleration of the muon beam are relatively easy since the beam is already bunched.

  4. Positron clouds within thunderstorms

    NASA Astrophysics Data System (ADS)

    Dwyer, Joseph R.; Smith, David M.; Hazelton, Bryna J.; Grefenstette, Brian W.; Kelley, Nicole A.; Lowell, Alexander W.; Schaal, Meagan M.; Rassoul, Hamid K.

    2015-08-01

    We report the observation of two isolated clouds of positrons inside an active thunderstorm. These observations were made by the Airborne Detector for Energetic Lightning Emissions (ADELE), an array of six gamma-ray detectors, which flew on a Gulfstream V jet aircraft through the top of an active thunderstorm in August 2009. ADELE recorded two 511 keV gamma-ray count rate enhancements, 35 s apart, each lasting approximately 0.2 s. The enhancements, which were approximately a factor of 12 above background, were both accompanied by electrical activity as measured by a flat-plate antenna on the underside of the aircraft. The energy spectra were consistent with a source mostly composed of positron annihilation gamma rays, with a prominent 511 keV line clearly visible in the data. Model fits to the data suggest that the aircraft was briefly immersed in clouds of positrons, more than a kilometre across. It is not clear how the positron clouds were created within the thunderstorm, but it is possible they were caused by the presence of the aircraft in the electrified environment.

  5. Positron excitation of neon

    NASA Technical Reports Server (NTRS)

    Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

    1990-01-01

    The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

  6. Positron implantation in solids

    SciTech Connect

    Ghosh, V.J.; Lynn, K.G.; Welch, D.O.

    1993-12-31

    The Monte Carlo technique for modeling positron prior to annihilation and electron implantation in semi-infinite metals is described. Particle implantation is modelled as a multistep process, a series of collisions with the atoms of the host material. In elastic collisions with neutral atoms there is no transfer of energy. The particle loses energy by several different channels, excitation of the electron gas, ionization of the ion cores, or, at low energies, by phonon excitation. These competing scattering mechanisms have been incorporated into the Monte Carlo framework and several different models are being used. Brief descriptions of these Monte Carlo schemes, as well as an analytic model for positron implantation are included. Results of the Monte Carlo simulations are presented and compared with expermental data. Problems associated with modeling positron implantation are discuss and the need for more expermental data on energy-loss in different materials is stressed. Positron implantation in multilayers of different metals is briefly described and extensions of this work to include a study of multilayers and heterostructures is suggested.

  7. Linac4 H⁻ ion sources.

    PubMed

    Lettry, J; Aguglia, D; Alessi, J; Andersson, P; Bertolo, S; Briefi, S; Butterworth, A; Coutron, Y; Dallocchio, A; David, N; Chaudet, E; Faircloth, D; Fantz, U; Fink, D A; Garlasche, M; Grudiev, A; Guida, R; Hansen, J; Haase, M; Hatayama, A; Jones, A; Koszar, I; Lallement, J-B; Lombardi, A M; Machado, C; Mastrostefano, C; Mathot, S; Mattei, S; Moyret, P; Nisbet, D; Nishida, K; O'Neil, M; Paoluzzi, M; Scrivens, R; Shibata, T; Steyaert, D; Thaus, N; Voulgarakis, G

    2016-02-01

    CERN's 160 MeV H(-) linear accelerator (Linac4) is a key constituent of the injector chain upgrade of the Large Hadron Collider that is being installed and commissioned. A cesiated surface ion source prototype is being tested and has delivered a beam intensity of 45 mA within an emittance of 0.3 π ⋅ mm ⋅ mrad. The optimum ratio of the co-extracted electron- to ion-current is below 1 and the best production efficiency, defined as the ratio of the beam current to the 2 MHz RF-power transmitted to the plasma, reached 1.1 mA/kW. The H(-) source prototype and the first tests of the new ion source optics, electron-dump, and front end developed to minimize the beam emittance are presented. A temperature regulated magnetron H(-) source developed by the Brookhaven National Laboratory was built at CERN. The first tests of the magnetron operated at 0.8 Hz repetition rate are described. PMID:26932021

  8. Linac4 H- ion sources

    NASA Astrophysics Data System (ADS)

    Lettry, J.; Aguglia, D.; Alessi, J.; Andersson, P.; Bertolo, S.; Briefi, S.; Butterworth, A.; Coutron, Y.; Dallocchio, A.; David, N.; Chaudet, E.; Faircloth, D.; Fantz, U.; Fink, D. A.; Garlasche, M.; Grudiev, A.; Guida, R.; Hansen, J.; Haase, M.; Hatayama, A.; Jones, A.; Koszar, I.; Lallement, J.-B.; Lombardi, A. M.; Machado, C.; Mastrostefano, C.; Mathot, S.; Mattei, S.; Moyret, P.; Nisbet, D.; Nishida, K.; O'Neil, M.; Paoluzzi, M.; Scrivens, R.; Shibata, T.; Steyaert, D.; Thaus, N.; Voulgarakis, G.

    2016-02-01

    CERN's 160 MeV H- linear accelerator (Linac4) is a key constituent of the injector chain upgrade of the Large Hadron Collider that is being installed and commissioned. A cesiated surface ion source prototype is being tested and has delivered a beam intensity of 45 mA within an emittance of 0.3 π ṡ mm ṡ mrad. The optimum ratio of the co-extracted electron- to ion-current is below 1 and the best production efficiency, defined as the ratio of the beam current to the 2 MHz RF-power transmitted to the plasma, reached 1.1 mA/kW. The H- source prototype and the first tests of the new ion source optics, electron-dump, and front end developed to minimize the beam emittance are presented. A temperature regulated magnetron H- source developed by the Brookhaven National Laboratory was built at CERN. The first tests of the magnetron operated at 0.8 Hz repetition rate are described.

  9. Field size consistency of nominally matched linacs.

    PubMed

    Kairn, T; Asena, A; Charles, P H; Hill, B; Langton, C M; Middlebrook, N D; Moylan, R; Trapp, J V

    2015-06-01

    Given that there is increasing recognition of the effect that sub-millimetre changes in collimator position can have on radiotherapy beam dosimetry, this study aimed to evaluate the potential variability in small field collimation that may exist between otherwise matched linacs. Field sizes and field output factors were measured using radiochromic film and an electron diode, for jaw- and MLC-collimated fields produced by eight dosimetrically matched Varian iX linacs (Varian Medical Systems, Palo Alto, USA). This study used nominal sizes from 0.6 × 0.6 to 10 × 10 cm(2), for jaw-collimated fields, and from 1 × 1 to 10 × 10 cm(2) for MLC-collimated fields, delivered from a zero (head up, beam directed vertically downward) gantry angle. Differences between the field sizes measured for the eight linacs exceeded the uncertainty of the film measurements and the repositioning uncertainty of the jaws and MLCs on one linac. The dimensions of fields defined by MLC leaves were more consistent between linacs, while also differing more from their nominal values than fields defined by orthogonal jaws. The field output factors measured for the different linacs generally increased with increasing measured field size for the nominal 0.6 × 0.6 to 1 × 1 cm(2) fields, and became consistent between linacs for nominal field sizes of 2 × 2 cm(2) and larger. The inclusion in radiotherapy treatment planning system beam data of small field output factors acquired in fields collimated by jaws (rather than the more-reproducible MLCs), associated with either the nominal or the measured field sizes, should be viewed with caution. The size and reproducibility of the fields (especially the small fields) used to acquire treatment planning data should be investigated thoroughly as part of the linac or planning system commissioning process. Further investigation of these issues, using different linac models, collimation systems and beam orientations, is recommended. PMID

  10. Cardiac positron emission tomography

    SciTech Connect

    Geltman, E.M.

    1985-12-01

    Positron emission tomography (PET) is a new technique for noninvasively assessing myocardial metabolism and perfusion. It has provided new insight into the dynamics of myocardial fatty acid and glucose metabolism in normal subjects, patients with ischemic heart disease and those with cardiomyopathies, documenting regionally depressed fatty acid metabolism during myocardial ischemia and infarction and spatial heterogeneity of fatty acid metabolism in patients with cardiomyopathy. Regional myocardial perfusion has been studied with PET using water, ammonia and rubidium labeled with positron emitters, permitting the noninvasive detection of hypoperfused zones at rest and during vasodilator stress. With these techniques the relationship between perfusion and the metabolism of a variety of substrates has been studied. The great strides that have been made in developing faster high-resolution instruments and producing new labeled intermediates indicate the promise of this technique for facilitating an increase in the understanding of regional metabolism and blood flow under normal and pathophysiologic conditions. 16 references, 9 figures, 2 tables.

  11. Commissioning Experience for the SNS Linac

    SciTech Connect

    Aleksandrov, A.; Assadi, S.; Campisi, I.; Chu, P.; Cousineau, S.; Danilov, V.; Dodson, B.G.; Galambos, J.; Jeon, D.; Henderson, S.; Holtkamp, N.; Kravchuk, L.; Kim, S.; Plum, M.; Tanke, E.; Stockli, M.

    2005-06-08

    The Spallation Neutron Source accelerator systems will deliver a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H- injector, capable of producing one-ms-long pulses at 60 Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. A 2.5 MeV beam from the Front End is accelerated to 86 MeV in a Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and then to 1 GeV in a Superconducting Linac. The staged beam commissioning of the accelerator complex is proceeding as component installation progresses. The Front End, Drift Tube Linac and part of the Coupled-Cavity Linac have been commissioned at ORNL. The primary design goals of peak current, transverse emittance and beam energy have been achieved. Results and status of the beam commissioning program will be presented.

  12. RFI-Based Ion Linac Systems

    NASA Astrophysics Data System (ADS)

    Swenson, Donald A.

    A new company, Ion Linac Systems, Inc., has been formed to promote the development, manufacture, and marketing of intense, RFI-based, Ion Linac Systems. The Rf Focused Interdigital (RFI) linac structure was invented by the author while at Linac Systems, LLC. The first step, for the new company, will be to correct a flaw in an existing RFI-based linac system and to demonstrate "good transmission" through the system. The existing system, aimed at the BNCT medical application, is designed to produce a beam of 2.5 MeV protons with an average beam current of 20 mA. In conjunction with a lithium target, it will produce an intense beam of epithermal neutrons. This system is very efficient, requiring only 180 kW of rf power to produce a 50 kW proton beam. In addition to the BNCT medical application, the RFI-based systems should represent a powerful neutron generator for homeland security, defence applications, cargo container inspection, and contraband detection. The timescale to the demonstration of "good transmission" is early fall of this year. Our website is www.ionlinacs.com.

  13. Positrons at Jefferson Laboratory

    SciTech Connect

    Thomas, A W

    2009-09-01

    We review the compelling case for establishing a capability to accelerate positrons at Jefferson Lab. The potential appplications range from the study of two-photon exchange and deeply-virtual Compton scattering to exploiting the charge current weak interaction to probe the flavor structure of hadrons and nuclei. There are also fascinating ideas for using such a capability to discover new physics beyond the Standard Model of nuclear and particle physics.

  14. Positron fraction, electron and positron spectra measured by AMS-02

    NASA Astrophysics Data System (ADS)

    Pizzolotto, Cecilia

    2016-07-01

    A precise measurement by AMS-02 of the electron spectrum up to 700 GeV and of the positron spectrum and positron fraction in primary cosmic rays up 500 GeV are presented. The combined measurement of the cosmic-ray electron and positron energy spectra and fraction provide a unique tool to improve our understanding of the production, acceleration and propagation mechanism of cosmic rays.

  15. Positron lifetime spectrometer using a DC positron beam

    DOEpatents

    Xu, Jun; Moxom, Jeremy

    2003-10-21

    An entrance grid is positioned in the incident beam path of a DC beam positron lifetime spectrometer. The electrical potential difference between the sample and the entrance grid provides simultaneous acceleration of both the primary positrons and the secondary electrons. The result is a reduction in the time spread induced by the energy distribution of the secondary electrons. In addition, the sample, sample holder, entrance grid, and entrance face of the multichannel plate electron detector assembly are made parallel to each other, and are arranged at a tilt angle to the axis of the positron beam to effectively separate the path of the secondary electrons from the path of the incident positrons.

  16. Induced radioisotopes in a linac treatment hall.

    PubMed

    Vega-Carrillo, Héctor René; de Leon-Martinez, Héctor Asael; Rivera-Perez, Esteban; Luis Benites-Rengifo, Jorge; Gallego, Eduardo; Lorente, Alfredo

    2015-08-01

    When linacs operate above 8MV an undesirable neutron field is produced whose spectrum has three main components: the direct spectrum due to those neutrons leaking out from the linac head, the scattered spectrum due to neutrons produced in the head that collides with the nuclei in the head losing energy and the third spectrum due to room-return effect. The third category of spectrum has mainly epithermal and thermal neutrons being constant at any location in the treatment hall. These neutrons induce activation in the linac components, the concrete walls and in the patient body. Here the induced radioisotopes have been identified in concrete samples located in the hall and in one of the wedges. The identification has been carried out using a gamma-ray spectrometer. PMID:25989748

  17. Energy Recovery Linacs for Commercial Radioisotope Production

    SciTech Connect

    Sy, Amy; Krafft, Geoffrey A.; Johnson, Rolland; Roberts, Tom; Boulware, Chase; Hollister, Jerry

    2015-09-01

    Photonuclear reactions with bremsstrahlung photon beams from electron linacs can generate radioisotopes of critical interest. An SRF Energy Recovery Linac (ERL) provides a path to a more diverse and reliable domestic supply of short-lived, high-value, high-demand isotopes in a more compact footprint and at a lower cost than those produced by conventional reactor or ion accelerator methods. Use of an ERL enables increased energy efficiency of the complex through energy recovery of the waste electron beam, high electron currents for high production yields, and reduced neutron production and shielding activation at beam dump components. Simulation studies using G4Beamline/GEANT4 and MCNP6 through MuSim, as well as other simulation codes, will design an ERL-based isotope production facility utilizing bremsstrahlung photon beams from an electron linac. Balancing the isotope production parameters versus energy recovery requirements will inform a choice of isotope production target for future experiments.

  18. Coupled-cavity drift-tube linac

    DOEpatents

    Billen, J.H.

    1996-11-26

    A coupled-cavity drift-tube linac (CCDTL) combines features of the Alvarez drift-tube linac (DTL) and the {pi}-mode coupled-cavity linac (CCL). In one embodiment, each accelerating cavity is a two-cell, 0-mode DTL. The center-to-center distance between accelerating gaps is {beta}{lambda}, where {lambda} is the free-space wavelength of the resonant mode. Adjacent accelerating cavities have oppositely directed electric fields, alternating in phase by 180 degrees. The chain of cavities operates in a {pi}/2 structure mode so the coupling cavities are nominally unexcited. The CCDTL configuration provides an rf structure with high shunt impedance for intermediate velocity charged particles, i.e., particles with energies in the 20-200 MeV range. 5 figs.

  19. Coupled-cavity drift-tube linac

    DOEpatents

    Billen, James H.

    1996-01-01

    A coupled-cavity drift-tube linac (CCDTL) combines features of the Alvarez drift-tube linac (DTL) and the .pi.-mode coupled-cavity linac (CCL). In one embodiment, each accelerating cavity is a two-cell, 0-mode DTL. The center-to-center distance between accelerating gaps is .beta..lambda., where .lambda. is the free-space wavelength of the resonant mode. Adjacent accelerating cavities have oppositely directed electric fields, alternating in phase by 180 degrees. The chain of cavities operates in a .pi./2 structure mode so the coupling cavities are nominally unexcited. The CCDTL configuration provides an rf structure with high shunt impedance for intermediate velocity charged particles, i.e., particles with energies in the 20-200 MeV range.

  20. LCLS LLRF Upgrades to the SLAC Linac

    SciTech Connect

    Akre, R.; Dowell, D.; Emma, P.; Frisch, J.; Hong, B.; Kotturi, K.; Krejcik, P.; Wu, J.; Byrd, J.; /LBL, Berkeley

    2007-10-04

    The Linac Coherent Light Source (LCLS) at SLAC will be the brightest X-ray laser in the world when it comes on line. In order to achieve the brightness a 200fS length electron bunch is passed through an undulator. To create the 200fS, 3kA bunch, a 10pS electron bunch, created from a photo cathode in an RF gun, is run off crest on the RF to set up a position to energy correlation. The bunch is then compressed by chicanes. The stability of the RF system is critical in setting up the position to energy correlation. Specifications derived from simulations require the RF system to be stable to below 200fS in several critical injector stations and the last kilometer of linac. The SLAC linac RF system is being upgraded to meet these requirements.

  1. EXPERIENCE WITH THE SNS SC LINAC

    SciTech Connect

    Zhang, Yan; Aleksandrov, Alexander V; Allen, Christopher K; Campisi, Isidoro E; Cousineau, Sarah M; Danilov, Viatcheslav; Galambos, John D; Holmes, Jeffrey A; Jeon, Dong-O; Kim, Sang-Ho; Pelaia II, Tom; Plum, Michael A; Shishlo, Andrei P

    2008-01-01

    The SNS superconducting linac (SCL) is designed to deliver 1 GeV, up to 1.56-MW pulsed H- beams for neutron production. Commissioning of the accelerator systems was completed in June 2006, and the maximum beam energy achieved was approximately 952 MeV. In 2007, the SCL was successfully tuned for 1.01-GeV beam during a test operation. In the linac tune-up, phase scan signature matching, drifting beam measurement, and linac radio frequency cavity phase scaling were applied. In this paper, we will introduce the experiences with the SCL, including the tune-up, beam loss, and beam activation, and briefly discuss beam parameter measurements

  2. Diagnostics For Recirculating And Energy Recovered Linacs

    SciTech Connect

    Geoffrey A. Krafft; Jean-Claude Denard

    2002-12-18

    In this paper, the electron beam diagnostics developed for recirculating electron accelerators will be reviewed. The main novelties in dealing with such accelerators are: to have sufficient information and control possibilities for the longitudinal phase space, to have means to accurately set the recirculation path length, and to have a means to distinguish the beam passes on measurements of position in the linac proper. The solutions to these problems obtained at Jefferson Laboratory and elsewhere will be discussed. In addition, more standard instrumentation (profiling and emittance measurements) will be reviewed in the context of recirculating linacs. Finally, and looking forward, electron beam diagnostics for applications to high current energy recovered linacs will be discussed.

  3. A Superconducting Linac Proton Driver at Fermilab

    NASA Astrophysics Data System (ADS)

    Foster, G. William

    2004-05-01

    A proton driver has emerged as the leading candidate for Fermilab's next near-term accelerator project. The preferred technical solution is an 8 GeV superconducting linac based on technology developed for TESLA and the Spallation Neutron Source (SNS). Its primary mission is to serve as a single-stage H- injector to prepare 2 MW "Super-Beams" for Neutrino experiments using the Fermilab Main Injector. The linac can also accelerate electrons, protons, and relativistic muons, permitting future applications such as a driver for an FEL, a long-pulse spallation source, the driver for an intense 8 GeV neutrino or kaon program, and potential applications to a neutrino factory or muon collider. The technical design of the 8 GeV linac, as well as the design of an alternative synchrotron based proton driver, will be described along with plans for project proposal and construction.

  4. S-Band Loads for SLAC Linac

    SciTech Connect

    Krasnykh, A.; Decker, F.-J.; LeClair, R.; /INTA Technologies, Santa Clara

    2012-08-28

    The S-Band loads on the current SLAC linac RF system were designed, in some cases, 40+ years ago to terminate 2-3 MW peak power into a thin layer of coated Kanthal material as the high power absorber [1]. The technology of the load design was based on a flame-sprayed Kanthal wire method onto a base material. During SLAC linac upgrades, the 24 MW peak klystrons were replaced by 5045 klystrons with 65+ MW peak output power. Additionally, SLED cavities were introduced and as a result, the peak power in the current RF setup has increased up to 240 MW peak. The problem of reliable RF peak power termination and RF load lifetime required a careful study and adequate solution. Results of our studies and three designs of S-Band RF load for the present SLAC RF linac system is discussed. These designs are based on the use of low conductivity materials.

  5. The Linac Cooherent Light Source (LCLS) Accelerator

    SciTech Connect

    Wu, Juhao; Emma, P.; /SLAC

    2007-03-21

    The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. Such an FEL requires a high energy, high brightness electron beam to drive the FEL instability to saturation. When fed by an RF-photocathode gun, and modified to include two bunch compressor chicanes, the SLAC linac will provide such a high quality beam at 14 GeV and 1-{micro}m normalized emittance. In this paper, we report on recent linac studies, including beam stability and tolerances, longitudinal and transverse feedback systems, conventional and time-resolved diagnostics, and beam collimation systems. Construction and installation of the injector through first bunch compressor will be completed by December 2006, and electron commissioning is scheduled to begin in January of 2007.

  6. Nonlinear positron acoustic solitary waves

    SciTech Connect

    Tribeche, Mouloud; Aoutou, Kamel; Younsi, Smain; Amour, Rabia

    2009-07-15

    The problem of nonlinear positron acoustic solitary waves involving the dynamics of mobile cold positrons is addressed. A theoretical work is presented to show their existence and possible realization in a simple four-component plasma model. The results should be useful for the understanding of the localized structures that may occur in space and laboratory plasmas as new sources of cold positrons are now well developed.

  7. Positron Implantation Profile in Kapton

    NASA Astrophysics Data System (ADS)

    Dryzek, J.; Dryzek, E.

    2006-11-01

    The discussion presented in the paper focuses on processes accompanying positron implantation in condensed matter. They finally constitute the positron implantation profile which generally does not exhibit the exponential behavior as it is concluded from the Monte Carlo simulation made using the EGSnrc 4.0 code. The simulation was performed for the kapton and two commonly used positron sources 22Na and 68Ge\\68Ga. New formula for the implantation profile was proposed.

  8. Multipass Beam Breakup in Energy Recovery Linacs

    SciTech Connect

    Eduard Pozdeyev; Christopher Tennant; Joseph Bisognano; M Sawamura; R. Hajima; T.I. Smith

    2005-03-19

    This paper is a compilation of several presentations on multipass beam breakup (BBU) in energy recovery linacs (ERL) given at the 32nd Advanced ICFA Beam Workshop on ERLs. The goal of this paper is to summarize the progress achieved in analytical, numerical, and experimental studies of the instability and outline available and proposed BBU mitigation techniques. In this paper, a simplified theory of multipass BBU in recirculating linacs is presented. Several BBU suppression techniques and their working principles are discussed. The paper presents an overview of available BBU codes. Results of experimental studies of multipass BBU at the Jefferson Laboratory (JLab) FEL Upgrade are described.

  9. Proton linacs for boron neutron capture therapy

    SciTech Connect

    Lennox, A.J. |

    1993-08-01

    Recent advances in the ability to deliver boron-containing drugs to brain tumors have generated interest in {approximately}4 MeV linacs as sources of epithermal neutrons for radiation therapy. In addition, fast neutron therapy facilities have been studying methods to moderate their beams to take advantage of the high cross section for epithermal neutrons on boron-10. This paper describes the technical issues involved in each approach and presents the motivation for undertaking such studies using the Fermilab linac. the problems which must be solved before therapy can begin are outlined. Status of preparatory work and results of preliminary measurements are presented.

  10. Laser Created Relativistic Positron Jets

    SciTech Connect

    Chen, H; Wilks, S C; Meyerhofer, D D; Bonlie, J; Chen, C D; Chen, S N; Courtois, C; Elberson, L; Gregori, G; Kruer, W; Landoas, O; Mithen, J; Murphy, C; Nilson, P; Price, D; Scheider, M; Shepherd, R; Stoeckl, C; Tabak, M; Tommasini, R; Beiersdorder, P

    2009-10-08

    Electron-positron jets with MeV temperature are thought to be present in a wide variety of astrophysical phenomena such as active galaxies, quasars, gamma ray bursts and black holes. They have now been created in the laboratory in a controlled fashion by irradiating a gold target with an intense picosecond duration laser pulse. About 10{sup 11} MeV positrons are emitted from the rear surface of the target in a 15 to 22-degree cone for a duration comparable to the laser pulse. These positron jets are quasi-monoenergetic (E/{delta}E {approx} 5) with peak energies controllable from 3-19 MeV. They have temperatures from 1-4 MeV in the beam frame in both the longitudinal and transverse directions. Positron production has been studied extensively in recent decades at low energies (sub-MeV) in areas related to surface science, positron emission tomography, basic antimatter science such as antihydrogen experiments, Bose-Einstein condensed positronium, and basic plasma physics. However, the experimental tools to produce very high temperature positrons and high-flux positron jets needed to simulate astrophysical positron conditions have so far been absent. The MeV temperature jets of positrons and electrons produced in our experiments offer a first step to evaluate the physics models used to explain some of the most energetic phenomena in the universe.

  11. The ATLAS Positron Experiment -- APEX

    SciTech Connect

    Ahmad, I.; Back, B.B.; Betts, R.R.; Dunford, R.; Kutschera, W.; Rhein, M.D.; Schiffer, J.P.; Wilt, P.; Wuosmaa, A.; Austin, S.M.; Kashy, E.; Winfield, J.S.; Yurkon, J.E.; Bazin, D.; Calaprice, F.P.; Young, A.; Chan, K.C.; Chisti, A.; Chowhury, P.; Greenberg, J.S.; Kaloskamis, N.; Lister, C.J.; Fox, J.D.; Roa, E.; Freedman, S.; Maier, M.R.; Freer, M.; Gazes, S.; Hallin, A.L.; Liu, M.; Happ, T.; Perera, A.; Wolfs, F.L.H.; Trainor, T.; Wolanski, M. |

    1994-03-01

    APEX -- the ATLAS Positron Experiment -- is designed to measure electrons and positrons emitted in heavy-ion collisions. Its scientific goal is to gain insight into the puzzling positron-line phenomena observed at the GSI Darmstadt. It is in operation at the ATLAS accelerator at Argonne National Lab. The assembly of the apparatus is finished and beginning 1993 the first positrons produced in heavy-ion collisions were observed. The first full scale experiment was carried out in December 1993, and the data are currently being analyzed. In this paper, the principles of operation are explained and a status report on the experiment is given.

  12. Error analysis in post linac to driver linac transport beam line of RAON

    NASA Astrophysics Data System (ADS)

    Kim, Chanmi; Kim, Eun-San

    2016-07-01

    We investigated the effects of magnet errors in the beam transport line connecting the post linac to the driver linac (P2DT) in the Rare Isotope Accelerator in Korea (RAON). The P2DT beam line is bent by 180-degree to send the radioactive Isotope Separation On-line (ISOL) beams accelerated in Linac-3 to Linac-2. This beam line transports beams with multi-charge state 132Sn45,46,47. The P2DT beam line includes 42 quadrupole, 4 dipole and 10 sextupole magnets. We evaluate the effects of errors on the trajectory of the beam by using the TRACK code, which includes the translational and the rotational errors of the quadrupole, dipole and sextupole magnets in the beam line. The purpose of this error analysis is to reduce the rate of beam loss in the P2DT beam line. The distorted beam trajectories can be corrected by using six correctors and seven monitors.

  13. Positron Emission Tomography (PET)

    SciTech Connect

    Welch, M.J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs.

  14. Positron Emission Tomography (PET)

    DOE R&D Accomplishments Database

    Welch, M. J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET.

  15. Quantum positron acoustic waves

    SciTech Connect

    Metref, Hassina; Tribeche, Mouloud

    2014-12-15

    Nonlinear quantum positron-acoustic (QPA) waves are investigated for the first time, within the theoretical framework of the quantum hydrodynamic model. In the small but finite amplitude limit, both deformed Korteweg-de Vries and generalized Korteweg-de Vries equations governing, respectively, the dynamics of QPA solitary waves and double-layers are derived. Moreover, a full finite amplitude analysis is undertaken, and a numerical integration of the obtained highly nonlinear equations is carried out. The results complement our previously published results on this problem.

  16. Vacuum system for superconducting LINAC at TIFR

    NASA Astrophysics Data System (ADS)

    Pillay, R. G.

    2008-05-01

    The superconducting heavy ion LINAC booster at the TIFR-BARC facility has been operational. Seven super conducting cryostats containing 4 quarter wave resonators each along with beam lines, bending magnets, switching magnet, diagnostics and vacuum system have been commissioned. The heart of the cryogenic system for the heavy ion superconducting LINAC booster is a custom-built liquid helium refrigerator made by Linde Kryotechnik, Switzerland. The Refrigerator is rated for 300 Watts at 4.5 K with a dual JT (Joule-Thomson valve) at the final cooling stage, which allows simultaneous connections to the cryogenic loads (the LINAC module cryostats) and to a liquid helium storage dewar (1000 litres). The two-phase helium at 4.5 K produced at the JT stage in the refrigerator is delivered to the cryostats through a cryogenic distribution system. The cryogenic distribution system for the LINAC is designed to deliver both liquid helium and liquid nitrogen to the cryostats. The details of UHV system, indigenously developed beam line components, pumps and module cryostats will be presented.

  17. A Stability of LCLS Linac Modulators

    SciTech Connect

    Decker, F.-J.; Krasnykh, A.; Morris, B.; Nguyen, M.; /SLAC

    2012-06-13

    Information concerning to a stability of LCLS RF linac modulators is allocated in this paper. In general a 'pulse-to-pulse' modulator stability (and RF phase as well) is acceptable for the LCLS commission and FEL programs. Further modulator stability improvements are possible and approaches are discussed based on our experimental results.

  18. Cyclotron and linac production of Ac-225.

    PubMed

    Melville, Graeme; Allen, Barry J

    2009-04-01

    Radium needles that were once implanted into tumours as a cancer treatment are now obsolete and constitute a radioactive waste problem, as their half-life is 1600 years. The reduction of radium by photonuclear transmutation by bombarding Ra-226 with high-energy photons from a medical linear accelerator (linac) has been investigated. A linac dose of 2800 Gy produced about 2.4 MBq (64 microCi) of Ra-225, which decays to Ac-225 and can then be used for 'Targeted Alpha Therapy' (TAT) of cancer. This result, while consistent with theoretical calculations, is far too low to be of practical use unless much larger quantities of radium are irradiated. The increasing application of Ac-225 for cancer therapy indicates the potential need for its increased production and availability. This paper investigates the possibility of producing of Ac-225 in commercial quantities, which could potentially reduce obsolete radioactive material and displace the need for expensive importation of Ac-225 from the USA and Russia in the years ahead. Scaled up production of Ac-225 could theoretically be achieved by the use of a high current cyclotron or linac. Production specifications are determined for a linac in terms of current, pulse length and frequency, as well as an examination of other factors such as radiation issues and radionuclei separation. Yields are compared with those calculated for the Australian National Cyclotron in Sydney. PMID:19135381

  19. Design of post linac to driver linac transport beam line in rare isotope accelerator

    NASA Astrophysics Data System (ADS)

    Kim, Chanmi; Kim, Eun-San

    2015-07-01

    We investigated the design of a beam transport line connecting the post linac to the driver linac (P2DT) in the Rare Isotope Accelerator (RAON). P2DT beam line is designed by 180° bending scheme to send the radioactive isotope separation on-line (ISOL) beams accelerated in the Linac-3 to Linac-2. The beam line is designed as a 180° bend for the transport of a multi-charge state 132Sn+45,+46,+47 beam. We used the TRACE 3-D, TRACK, and ORBIT codes to design the optics system, which also includes two bunchers and ten sextupole magnets for chromaticity compensation. The transverse emittance growth is minimized by adopting mirror symmetric optics and by correcting second-order aberrations using sextupoles. We report on the multi-charge state beam transport performance of the designed beam line. The main characteristics of the P2DT line are to minimize beam loss and the growth of emittance, and for charge stripping. Beam optics for P2DT is optimized for reducing beam loss and charge stripping. As Linac-3 may accelerate the stable beam and radioactive beam simultaneously, P2DT line also transports the stable beam and radioactive beam simultaneously. Thus, we need a RF switchyard to send the stable beam to the ISOL target and the radioactive beam to the high-energy experimental area in Linac-2 end.

  20. Positron production within our atmosphere

    NASA Astrophysics Data System (ADS)

    Dwyer, Joseph

    2016-04-01

    Positrons are commonly produced within our atmosphere by cosmic rays and the decay radioactive isotopes. Energetic positrons are also produced by pair production from the gamma rays generated by relativistic runaway electrons. Indeed, such positrons have been detected in Terrestrial Electron Beams (TEBs) in the inner magnetosphere by Fermi/GBM. In addition, positrons play an important role in relativistic feedback discharges (also known as dark lightning). Relativistic feedback models suggest that these discharges may be responsible for Terrestrial Gamma-ray Flashes (TGFs) and some gamma-ray glows. When producing TGFs, relativistic feedback discharges may generate large, lightning-like currents with current moments reaching hundreds of kA-km. In addition, relativistic feedback discharges also may limit the electric field that is possible in our atmosphere, affecting other mechanisms for generating runaway electrons. It is interesting that positrons, often thought of as exotic particles, may play an important role in thunderstorm processes. In this presentation, the role of positrons in high-energy atmospheric physics will be discussed. The unusual observation of positron clouds inside a thunderstorm by the ADELE instrument on an NCAR/NSF Gulfstream V aircraft will also be described. These observations illustrate that we still have much to learn about positron production within our atmosphere.

  1. Portable Positron Measurement System (PPMS)

    SciTech Connect

    2011-01-01

    Portable Positron Measurement System (PPMS) is an automated, non-destructive inspection system based on positron annihilation, which characterizes a material's in situatomic-level properties during the manufacturing processes of formation, solidification, and heat treatment. Simultaneous manufacturing and quality monitoring now are possible. Learn more about the lab's project on our facebook site http://www.facebook.com/idahonationallaboratory.

  2. Cyclotrons and positron emitting radiopharmaceuticals

    SciTech Connect

    Wolf, A.P.; Fowler, J.S.

    1984-01-01

    The state of the art of Positron Emission Tomography (PET) technology as related to cyclotron use and radiopharmaceutical production is reviewed. The paper discusses available small cyclotrons, the positron emitters which can be produced and the yields possible, target design, and radiopharmaceutical development and application. 97 refs., 12 tabs. (ACR)

  3. Portable Positron Measurement System (PPMS)

    ScienceCinema

    None

    2013-05-28

    Portable Positron Measurement System (PPMS) is an automated, non-destructive inspection system based on positron annihilation, which characterizes a material's in situatomic-level properties during the manufacturing processes of formation, solidification, and heat treatment. Simultaneous manufacturing and quality monitoring now are possible. Learn more about the lab's project on our facebook site http://www.facebook.com/idahonationallaboratory.

  4. Plasma Wakefield Acceleration of Positrons

    NASA Astrophysics Data System (ADS)

    Gessner, Spencer

    2016-03-01

    Recent particle beam and laser-driven plasma wakefield experiments have produced high-quality electron beams accelerated by a GeV or more in less than a meter. Efforts are underway to put these beams to work as sources for free-electron lasers. By contrast, little work has been done to demonstrate the tractability of plasma wakefield acceleration (PWFA) of positrons beams. The reasons for this are threefold: 1) positron beams are only useful for high-energy physics experiments, whereas electron beams are also useful as light sources, 2) there is a dearth of positron sources for PWFA experiments, and 3) the dynamics of accelerating positron beams in plasma is fundamentally different than that of electron beams. This talk will focus on the physics of accelerating positrons in plasma and contrast the dynamics of electron and positron beam-driven nonlinear plasma wakes. We describe recent experiments at the FACET test facility at SLAC National Accelerator Laboratory that for the first time demonstrate high-gradient acceleration of a positron beams in plasma. We also discuss an alternative acceleration technique called hollow channel acceleration that aims to symmetrize the dynamics of electron and positron beam-driven wakes.

  5. Positron Emission Tomography.

    PubMed

    Lameka, Katherine; Farwell, Michael D; Ichise, Masanori

    2016-01-01

    Positron emission tomography (PET) is a minimally invasive imaging procedure with a wide range of clinical and research applications. PET allows for the three-dimensional mapping of administered positron-emitting radiopharmaceuticals such as (18)F-fluorodeoxyglucose (for imaging glucose metabolism). PET enables the study of biologic function in both health and disease, in contrast to magnetic resonance imaging (MRI) and computed tomography (CT), that are more suited to study a body's morphologic changes, although functional MRI can also be used to study certain brain functions by measuring blood flow changes during task performance. This chapter first provides an overview of the basic physics principles and instrumentation behind PET methodology, with an introduction to the merits of merging functional PET imaging with anatomic CT or MRI imaging. We then focus on clinical neurologic disorders, and reference research on relevant PET radiopharmaceuticals when applicable. We then provide an overview of PET scan interpretation and findings in several specific neurologic disorders such as dementias, epilepsy, movement disorders, infection, cerebrovascular disorders, and brain tumors. PMID:27432667

  6. Positron driven plasma wakefields

    NASA Astrophysics Data System (ADS)

    Pinkerton, S.; Shi, Y.; Huang, C.; An, W.; Mori, W. B.; Muggli, P.

    2010-11-01

    The LHC is producing high-energy, high-charge proton bunches (1e11 protons at 1-7 TeV each) that could be used to accelerate ``witness'' electron bunches to TeV range eneregies via a plasma wakefield accelerator (PWFA). Simulations [1] suggest that a proton ``drive'' bunch is able to excite large wakefields if the bunch size is on the order of 100 μm; however, the LHC paramters are currently on the 1 cm scale. SLAC'S FACET is able to supply positorn bunchs with the ideal parameters for driving a PWFA. Although at lower energy (2e10 positrons at 23 GeV each), initial simiulations in QuickPIC show that the physics of a positron drive bunch is very similar to that of a proton drive bunch. Differences in the physics arise from the mass difference: slower dephasing but faster transverse bunch evolution. Other considerations include driver head erosion and purity of the wakefield ion column. The physics of positive drivers for PWFA and the viability of this scheme for future high-energy colliders will be investigated at SLAC's FACET.[4pt] [1] Caldwell, et al. Nature Physics 5, 363 (2009).[0pt] [2] C.H. Huang, et al., J. Comp. Phys., 217(2), 658, (2006).

  7. Construction and commissioning of the positron accumulator ring for the APS

    SciTech Connect

    Borland, M.

    1994-12-31

    The injector for the Advanced Photon Source (APS) consists of a 200-MeV electron linac, a 450-MeV position linac, a positron accumulator ring (PAR). and a 7-GeV synchrotron. The purpose of the PAR is to accumulate, and damp positrons from the 60Hz linac during each cycle of the 2Hz synchrotron, thus increasing the fill rate for the main ring. Construction of the PAR was recently completed, and commissioning is well underway. The PAR contains eight conventional 1.5T, flat field, 45{degrees} dipole magnets with an {approximately} 1m bending radius and no gradient: adjustment of the damping partition was achieved with 25.5{degrees} edge angles. Four families of quadrupole magnets provide focusing, with each dipole closely bracketed by two quadrupoles. Ten sextupole magnets provide both steering and chromatic correction. Extensive magnetic measurements have characterized saturation-dependent effective length in the dipoles and interaction among the closely-spaced, large-aperture dipoles, quadrupoles and sextupoles. For injection and extraction, PAR employs three delay-line kickers with {approximately} 120ns rise and fall times, and a single transformer septum magnet with a 2mm septum wall. A first-harmonic rf system is used to capture positrons and a twelfth-harmonic system provides an additional three-fold bunch compression. Diagnostics include 16 stripline beam position monitors, six fluorescent screens, dual fast/integrating current transformers, a tune measurement system, and two synchrotron light ports. Commissioning of the PAR with electrons has proceeded rapidly, starting at 150MeV and progressing to 450MeV as higher energy electrons became available. Alignment and dipole uniformity are sufficiently good that beam can be stored without the use of steering magnets. Experiments to date show excellent agreement with the machine model. Accumulation at 6Hz and extraction at 2Hz has been performed with essentially 100% efficiency.

  8. Positron-acoustic solitary waves in a magnetized electron-positron-ion plasma with nonthermal electrons and positrons

    NASA Astrophysics Data System (ADS)

    Rahman, M. M.; Alam, M. S.; Mamun, A. A.

    2015-05-01

    Obliquely propagating positron-acoustic solitary waves (PASWs) in a magnetized electron-positron-ion plasma (containing nonthermal hot positrons and electrons, inertial cold positrons, and immobile positive ions) are precisely investigated by deriving the Zakharov-Kuznetsov equation. It is found that the characteristics of the PASWs are significantly modified by the effects of external magnetic field, obliqueness, nonthermality of hot positrons and electrons, temperature ratio of hot positrons and electrons, and respective number densities of hot positrons and electrons. The findings of our results can be employed in understanding the localized electrostatic structures and the characteristics of PASWs in various space and laboratory plasmas.

  9. Linac mechanic QA using a cylindrical phantom

    NASA Astrophysics Data System (ADS)

    Mamalui-Hunter, Maria; Li, Harold; Low, Daniel A.

    2008-09-01

    Precise mechanical operation of a linear accelerator (linac) is critical for accurate radiation therapy dose delivery. Quantitative procedures for linac mechanical quality assurance (QA) used in the standard of care are time consuming and therefore conducted on a relatively infrequent basis. We present a method for evaluating the mechanical performance of a linac based on a series of projection portal images of a prototype cylindrical phantom with embedded radiopaque fiducial markers. The marker autodetection process included modeling imager response to the radiation beam where the projected cylinder attenuation yielded a non-uniform image background. The linac mechanical characteristics were estimated based on nonlinear multi-objective optimization of the projected marker locations. The estimated geometry parameters for the tested commercial model were gantry angle deviation 0.075 ± 0.076° (1 SD), gantry sag 0.026 ± 0.02°, source-to-axis distance SAD 998.3 ± 1.7 mm, source-to-detector distance SDD 1493 ± 5.0 mm, couch vertical motion 0.6 ± 0.45 mm, couch rotation 0.154 ± 0.1° and average linac rotation center (1.02, -0.27, -0.37) ± (0.36,0.333,1.20) mm relative to the laser intersection. The imager shift was [-0.44, 2.6] ± [0.20, 1.1] mm and the imager orientation was in-plane rotation 0.05 ± 0.03°, roll -0.14 ± 0.09° and pitch -0.9 ± 0.604°. The performance of this procedure concerning marker detection and optimization was examined by comparing the detected set of marker coordinates to its back-calculated counterpart for three subgroups of markers: central, wall and intermediate relative to the center of the phantom. The maximum difference was less than 0.25 mm with a mean of 0.146 mm and a standard deviation of 0.07 mm. The clinical use of this automated procedure will allow more efficient, more thorough, and more frequent mechanical linac QA.

  10. Linac mechanic QA using a cylindrical phantom.

    PubMed

    Mamalui-Hunter, Maria; Li, Harold; Low, Daniel A

    2008-09-21

    Precise mechanical operation of a linear accelerator (linac) is critical for accurate radiation therapy dose delivery. Quantitative procedures for linac mechanical quality assurance (QA) used in the standard of care are time consuming and therefore conducted on a relatively infrequent basis. We present a method for evaluating the mechanical performance of a linac based on a series of projection portal images of a prototype cylindrical phantom with embedded radiopaque fiducial markers. The marker autodetection process included modeling imager response to the radiation beam where the projected cylinder attenuation yielded a non-uniform image background. The linac mechanical characteristics were estimated based on nonlinear multi-objective optimization of the projected marker locations. The estimated geometry parameters for the tested commercial model were gantry angle deviation 0.075 +/- 0.076 degrees (1 SD), gantry sag 0.026 +/- 0.02 degrees , source-to-axis distance SAD 998.3 +/- 1.7 mm, source-to-detector distance SDD 1493 +/- 5.0 mm, couch vertical motion 0.6 +/- 0.45 mm, couch rotation 0.154 +/- 0.1 degrees and average linac rotation center (1.02, -0.27, -0.37) +/- (0.36,0.333,1.20) mm relative to the laser intersection. The imager shift was [-0.44, 2.6] +/- [0.20, 1.1] mm and the imager orientation was in-plane rotation 0.05 +/- 0.03 degrees , roll -0.14 +/- 0.09 degrees and pitch -0.9 +/- 0.604 degrees . The performance of this procedure concerning marker detection and optimization was examined by comparing the detected set of marker coordinates to its back-calculated counterpart for three subgroups of markers: central, wall and intermediate relative to the center of the phantom. The maximum difference was less than 0.25 mm with a mean of 0.146 mm and a standard deviation of 0.07 mm. The clinical use of this automated procedure will allow more efficient, more thorough, and more frequent mechanical linac QA. PMID:18723927

  11. Positron emission mammography imaging

    SciTech Connect

    Moses, William W.

    2003-10-02

    This paper examines current trends in Positron Emission Mammography (PEM) instrumentation and the performance tradeoffs inherent in them. The most common geometry is a pair of parallel planes of detector modules. They subtend a larger solid angle around the breast than conventional PET cameras, and so have both higher efficiency and lower cost. Extensions to this geometry include encircling the breast, measuring the depth of interaction (DOI), and dual-modality imaging (PEM and x-ray mammography, as well as PEM and x-ray guided biopsy). The ultimate utility of PEM may not be decided by instrument performance, but by biological and medical factors, such as the patient to patient variation in radiotracer uptake or the as yet undetermined role of PEM in breast cancer diagnosis and treatment.

  12. Online beam energy measurement of Beijing electron positron collider II linear accelerator.

    PubMed

    Wang, S; Iqbal, M; Liu, R; Chi, Y

    2016-02-01

    This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper. PMID:26931839

  13. Head-tail instability caused by electron clouds in positron storage rings

    PubMed

    Ohmi; Zimmermann

    2000-10-30

    In positron or proton storage rings with many closely spaced bunches, an electron cloud can build up in the vacuum chamber due to photoemission or secondary emission. We discuss the possibility of a single-bunch two-stream instability driven by this electron cloud. Depending on the strength of the beam-electron interaction, the chromaticity and the synchrotron oscillation frequency, this instability either resembles a linac beam breakup or a head-tail instability. We present computer simulations of the instabilities, and compare the simulation results with analytical estimates. PMID:11041936

  14. Online beam energy measurement of Beijing electron positron collider II linear accelerator

    NASA Astrophysics Data System (ADS)

    Wang, S.; Iqbal, M.; Liu, R.; Chi, Y.

    2016-02-01

    This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper.

  15. Intense source of slow positrons

    NASA Astrophysics Data System (ADS)

    Perez, P.; Rosowsky, A.

    2004-10-01

    We describe a novel design for an intense source of slow positrons based on pair production with a beam of electrons from a 10 MeV accelerator hitting a thin target at a low incidence angle. The positrons are collected with a set of coils adapted to the large production angle. The collection system is designed to inject the positrons into a Greaves-Surko trap (Phys. Rev. A 46 (1992) 5696). Such a source could be the basis for a series of experiments in fundamental and applied research and would also be a prototype source for industrial applications, which concern the field of defect characterization in the nanometer scale.

  16. [Fundamentals of positron emission tomography].

    PubMed

    Ostertag, H

    1989-07-01

    Positron emission tomography is a modern radionuclide method of measuring physiological quantities or metabolic parameters in vivo. The method is based on: (1) radioactive labelling with positron emitters; (2) the coincidence technique for the measurement of the annihilation radiation following positron decay; (3) analysis of the data measured using biological models. The basic aspects and problems of the method are discussed. The main fields of future research are the synthesis of new labelled compounds and the development of mathematical models of the biological processes to be investigated. PMID:2667029

  17. Cosmic Ray Positrons from Pulsars

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2010-01-01

    Pulsars are potential Galactic sources of positrons through pair cascades in their magnetospheres. There are, however, many uncertainties in establishing their contribution to the local primary positron flux. Among these are the local density of pulsars, the cascade pair multiplicities that determine the injection rate of positrons from the pulsar, the acceleration of the injected particles by the pulsar wind termination shock, their rate of escape from the pulsar wind nebula, and their propagation through the interstellar medium. I will discuss these issues in the context of what we are learning from the new Fermi pulsar detections and discoveries.

  18. Investigations on a hybrid positron source with a granular converter

    NASA Astrophysics Data System (ADS)

    Artru, X.; Chaikovska, I.; Chehab, R.; Chevallier, M.; Dadoun, O.; Furukawa, K.; Guler, H.; Kamitani, T.; Miyahara, F.; Satoh, M.; Sievers, P.; Suwada, T.; Umemori, K.; Variola, A.

    2015-07-01

    Promising results obtained with crystal targets for positron production led to the elaboration of a hybrid source made of an axially oriented tungsten crystal, as a radiator, and an amorphous tungsten converter. If the converter is granular, made of small spheres, the heat dissipation is greatly enhanced and the thermal shocks reduced, allowing the consideration of such device for the future linear colliders. A positron source of this kind is investigated. Previous simulations have shown very promising results for the yield as for the energy deposition and the PEDD (Peak Energy Deposition Density). Here, we present detailed simulations made in this granular converter with emphasis on the energy deposition density, which is a critical parameter as learned from the breakdown of the SLC target. A test on the KEKB linac is foreseen; it will allow a determination of the energy deposited and the PEDD in the converter through temperature measurements. Four granular converters, made of W spheres of mm radius have been built at LAL-Orsay; they will be installed at KEK and compared to compact converters. A description of the experimental layout at KEK is provided. Applications to future linear colliders as CLIC and ILC are considered.

  19. LLRF System Upgrade for the SLAC Linac

    SciTech Connect

    Hong, Bo; Akre, Ron; Pacak, Vojtech; /SLAC

    2012-07-06

    The Linac Coherent Light Source (LCLS) at SLAC is in full user operation and has met the stability goals for stable lasing. The 250pC bunch can be compressed to below 100fS before passing through an undulator. In a new mode of operation a 20pC bunch is compressed to about 10fS. Experimenters are regularly using this shorter X-ray pulse and getting pristine data. The 10fS bunch has timing jitter on the order of 100fS. Physicists are requesting that the RF system achieve better stability to reduce timing jitter. Drifts in the RF system require longitudinal feedbacks to work over large ranges and errors result in reduced performance of the LCLS. A new RF system is being designed to help diagnose and reduce jitter and drift in the SLAC linac.

  20. High Current Energy Recovery Linac at BNL

    SciTech Connect

    Vladimir N. Litvinenko; Donald Barton; D. Beavis; Ilan Ben-Zvi; Michael Blaskiewicz; J.M. Brennan; A. Burrill; R. Calaga; P. Cameron; X. Chang; Roger Connolly; D. Gassner; H. Hahn; A. Hershcovitch; H.C. Hseuh; P. Johnson; D. Kayran; J. Kewisch; R. Lambiase; G. McIntyre; W. Meng; T. C. Nehring; A. Nicoletti; D. Pate; J. Rank; T. Roser; T. Russo; J. Scaduto; K. Smith; T. Srinivasan-Rao; N. Williams; K.-C. Wu; Vitaly Yakimenko; K. Yip; A. Zaltsman; Y. Zhao; H. Bluem; A. Burger; Mike Cole; A. Favale; D. Holmes; John Rathke; Tom Schultheiss; A. Todd; J. Delayen; W. Funk; L. Phillips; Joe Preble

    2004-08-01

    We present the design, the parameters of a small test Energy Recovery Linac (ERL) facility, which is under construction at Collider-Accelerator Department, BNL. This R&D facility has goals to demonstrate CW operation of ERL with average beam current in the range of 0.1 - 1 ampere, combined with very high efficiency of energy recovery. A possibility for future up-grade to a two-pass ERL is considered. The heart of the facility is a 5-cell 700 MHz super-conducting RF linac with HOM damping. Flexible lattice of ERL provides a test-bed for testing issues of transverse and longitudinal instabilities and diagnostics of intense CW e-beam. ERL is also perfectly suited for a far-IR FEL. We present the status and our plans for construction and commissioning of this facility.

  1. Re-circulating linac vacuum system

    SciTech Connect

    Wells, Russell P.; Corlett, John N.; Zholents, Alexander A.

    2003-05-09

    The vacuum system for a proposed 2.5 GeV, 10{Mu}A recirculating linac synchrotron light source [1] is readily achievable with conventional vacuum hardware and established fabrication processes. Some of the difficult technical challenges associated with synchrotron light source storage rings are sidestepped by the relatively low beam current and short beam lifetime requirements of a re-circulating linac. This minimal lifetime requirement leads directly to relatively high limits on the background gas pressure through much of the facility. The 10{Mu}A average beam current produces very little synchrotron radiation induced gas desorption and thus the need for an ante-chamber in the vacuum chamber is eliminated. In the arc bend magnets, and the insertion devices, the vacuum chamber dimensions can be selected to balance the coherent synchrotron radiation and resistive wall wakefield effects, while maintaining the modest limits on the gas pressure and minimal outgassing.

  2. HIGH CURRENT ENERGY RECOVERY LINAC AT BNL.

    SciTech Connect

    LITVINENKO,V.N.; BEN-ZVI,I.; BARTON,D.S.; ET AL.

    2005-05-16

    We present the design and parameters of an energy recovery linac (ERL) facility, which is under construction in the Collider-Accelerator Department at BNL. This R&D facility has the goal of demonstrating CW operation of an ERL with an average beam current in the range of 0.1-1 ampere and with very high efficiency of energy recovery. The possibility of a future upgrade to a two-pass ERL is also being considered. The heart of the facility is a 5-cell 703.75 MHz super-conducting RF linac with strong Higher Order Mode (HOM) damping. The flexible lattice of the ERL provides a test-bed for exploring issues of transverse and longitudinal instabilities and diagnostics of intense CW electron beams. This ERL is also perfectly suited for a far-IR FEL. We present the status and plans for construction and commissioning of this facility.

  3. New high power linacs and beam physics

    SciTech Connect

    Wangler, T.P.; Gray, E.R.; Nath, S.; Crandall, K.R.; Hasegawa, K.

    1997-08-01

    New high-power proton linacs must be designed to control beam loss, which can lead to radioactivation of the accelerator. The threat of beam loss is increased significantly by the formation of beam halo. Numerical simulation studies have identified the space-charge interactions, especially those that occur in rms mismatched beams, as a major concern for halo growth. The maximum-amplitude predictions of the simulation codes must be subjected to independent tests to confirm the validity of the results. Consequently, the authors compare predictions from the particle-core halo models with computer simulations to test their understanding of the halo mechanisms that are incorporated in the computer codes. They present and discuss scaling laws that provide guidance for high-power linac design.

  4. The source development lab linac at BNL

    SciTech Connect

    Graves, W.S.; Johnson, E.D.; Raubenheimer, T.O.

    1996-12-01

    A 210 MeV SLAC-type electron linac is currently under construction at BNL as part of the Source Development Laboratory. A 1.6 cell RF photoinjector is employed as the high brightness electron source which is excited by a frequency tripled Titanium:Sapphire laser. This linac will be used for several source development projects including a short bunch storage ring, and a series of FEL experiments based on the 10 m long NISUS undulator. The FEL will be operated as either a SASE or seeded beam device using the Ti:Sapp laser. For the seeded beam experiments; direct amplification, harmonic generation, and chirped pulse amplification modes will be studied, spanning an output wavelength range from 900 nm down to 100 nm. This paper presents the project`s design parameters and results of recent modeling using the PARMELA and MAD simulation codes.

  5. Linac Coherent Light Source Monte Carlo Simulation

    2006-03-15

    This suite consists of codes to generate an initial x-ray photon distribution and to propagate the photons through various objects. The suite is designed specifically for simulating the Linac Coherent Light Source, and x-ray free electron laser (XFEL) being built at the Stanford Linear Accelerator Center. The purpose is to provide sufficiently detailed characteristics of the laser to engineers who are designing the laser diagnostics.

  6. Beam dynamics in heavy ion induction LINACS

    SciTech Connect

    Smith, L.

    1981-10-01

    Interest in the use of an induction linac to accelerate heavy ions for the purpose of providing the energy required to initiate an inertially confined fusion reaction has stimulated a theoretical effort to investigate various beam dynamical effects associated with high intensity heavy ion beams. This paper presents a summary of the work that has been done so far; transverse, longitudinal and coupled longitudinal transverse effects are discussed.

  7. Photocathodes for the energy recovery linacs

    SciTech Connect

    Rao, T; Burrill, A; Chang, X Y; Smedley, J; Nishitani, T; Garcia, C Hernandez; Poelker, M; Seddon, E; Hannon, F E; Sinclair, C K; Lewellen, J; Feldman, D

    2005-03-19

    This paper presents an overview of existing and emerging technologies on electron sources that can service various Energy Recovering Linacs under consideration. Photocathodes that can deliver average currents from 1 mA to 1 A, the pros and cons associated with these cathodes are addressed. Status of emerging technologies such as secondary emitters, cesiated dispenser cathodes, field and photon assisted field emitters and super lattice photocathodes are also reviewed.

  8. PHOTOCATHODES FOR THE ENERGY RECOVERY LINACS.

    SciTech Connect

    RAO, T.; BURRILL, A.; CHANG, X.Y.; SMEDLEY, J.; ET AL.

    2005-03-19

    This paper presents an overview of existing and emerging technologies on electron sources that can service various Energy Recovering Linacs under consideration. Photocathodes that can deliver average currents from 1 mA to 1 A, the pros and cons associated with these cathodes are addressed. Status of emerging technologies such as secondary emitters, cesiated dispenser cathodes, field and photon assisted field emitters and super lattice photocathodes are also reviewed.

  9. LINAC for ADS application - accelerator technologies

    SciTech Connect

    Garnett, Robert W; Sheffreld, Richard L

    2009-01-01

    Sifnificant high-current, high-intensity accelerator research and development have been done in the recent past in the US, centered primarily at Los Alamos National Laboratory. These efforts have included designs for the Accelerator Production of Tritium Project, Accelerator Transmutation of Waste, and Accelerator Driven Systems, as well as many others. This past work and some specific design principles that were developed to optimie linac designs for ADS and other high-intensity applications will be discussed briefly.

  10. Photocathodes for the energy recovery linacs

    NASA Astrophysics Data System (ADS)

    Rao, T.; Burrill, A.; Chang, X. Y.; Smedley, J.; Nishitani, T.; Hernandez Garcia, C.; Poelker, M.; Seddon, E.; Hannon, F. E.; Sinclair, C. K.; Lewellen, J.; Feldman, D.

    2006-02-01

    This paper presents an overview of existing and emerging technologies on electron sources that can service various energy recovering linacs under consideration. Photocathodes that can deliver average currents from 1 mA to 1 A, the pros and cons associated with these cathodes are addressed. Status of emerging technologies such as secondary emitters, cesiated dispenser cathodes, field and photon assisted field emitters and super lattice photocathodes are also reviewed.

  11. LINAC-based transuranic waste characterization system

    SciTech Connect

    Schultz, F.J.; Womble, P.C.; Vourvopoulos, G.; Roberts, M.L.

    1994-12-31

    Remote-handled transuranic nuclear waste poses a particular challenge for assaying due to the high neutron and gamma ray background that emanates from the non-fissile, but highly radioactive material, contained with the waste. The utilization of a RFQ linac with a neutron flux has shown that, in principle, the differential die-away technique can reliably assay this special class of nuclear waste.

  12. Study for a proposed Phase I Energy Recovery Linac (ERL) Synchrotron Light Source at Cornell University

    SciTech Connect

    Sol M. Gruner and Maury Tigner, eds.; Ivan Bazarov; Sergey Belomestnykh; Don Bilderback; Ken Finkelstein; Ernie Fontes; Steve Gray; Sol M. Gruner; Geoff Krafft; Lia Merminga; Hasan Padamsee; Ray Helmke; Qun Shen; Joe Rogers; Charles Sinclair; Richard Talman; Maury Tigner

    2001-07-01

    Synchrotron radiation (SR) has become an essential and rapidly growing tool across the sciences and engineering. World-wide, about 70 SR sources are in various stages of operation, construction, or planning, representing a cumulative investment on many billions of dollars and serving a growing research community well in excess of 10,000 scientists. To date, all major SR x-ray facilities are based on electron (or positron) storage rings. Given the expected continued growth, importance and expense of SR sources, it is important to ask if there are alternatives to the storage ring SR source which offer advantages of capability or cost. A step in this direction is being taken by the SR community with the proposed developments of linac-based x-ray free-electron lasers (XFELs) utilizing the self-amplified spontaneous emission process (SASE). However, the versatility of modern developments in accelerator physics, as applied to synchrotron radiation, is not limited to storage rings or XFELs. New developments in laser driven photoinjectors and superconducting linac technology open new and exciting possibilities for novel SR-generating machines which offer extraordinary capabilities and promise to catalyze whole new areas of SR-based science.

  13. Multiple beam induction linac research at LBL

    SciTech Connect

    Garvey, T.; Eylon, S.; Fessenden, T.J.; Hahn, K.; Henestroza, E.; Keefe, D.

    1990-06-01

    We present results of progress on the LBL multiple beam induction linac experiment (MBE-4). This machine models the accelerator physics of the electric-focused portion of a driver for heavy ion inertial confinement fusion. Four beams of cesium ions are accelerated in common through twenty four induction gaps while being separately focused in individual electrostatic AG focusing channels. Early experiments have demonstrated current amplification in the linac, from 10 mA to 90 mA per beam. This is achieved both by acceleration (from 200 keV to 1 MeV) and by carefully controlled bunch compression. Recent experiments have concentrated on studies of beams extracted from an ion source which produces 5 mA cesium beams at emittances near 0.03 {pi} mm-mrad (normalized). Experiments and theory show a growth of emittance (by about a factor of 2) as these beams are accelerated through the linac. Results of recent measurements of the transverse emittance behavior of these strongly space-charge-dominated ion beams are reviewed and compared with theory. 9 refs., 3 figs.

  14. Wake fields in SLAC Linac Collimators

    SciTech Connect

    Novokhatski, Alexander; Decker, F. -J.; Smith, H.; Sullivan, M.

    2014-12-02

    When a beam travels near collimator jaws, it gets an energy loss and a transverse kick due to the backreaction of the beam field diffracted from the jaws. The effect becomes very important for an intense short bunch when a tight collimation of the background beam halo is required. In the Linac Coherent Light Source at SLAC a collimation system is used to protect the undulators from radiation due to particles in the beam halo. The halo is most likely formed from gun dark current or dark current in some of the accelerating sections. However, collimators are also responsible for the generation of wake fields. The wake field effect from the collimators not only brings an additional energy jitter and change in the trajectory of the beam, but it also rotates the beam on the phase plane, which consequently leads to a degradation of the performance of the Free Electron Laser at the Linac Coherent Light Source. In this paper, we describe a model of the wake field radiation in the SLAC linac collimators. We use the results of a numerical simulation to illustrate the model. Based on the model, we derive simple formulas for the bunch energy loss and the average kick. In addition, we also present results from experimental measurements that confirm our model.

  15. Positron annihilation spectroscopy with magnetically analyzed beams

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Holt, W. H.; Mock, W., Jr.

    1982-01-01

    Lifetime measurements with magnetically analyzed positron beams were made in condensed media with uniform and non-uniform properties. As expected, the lifetime values with magnetically analyzed positron beams in uniform targets are similar to those obtained with conventional positron sources. The lifetime values with magnetically analyzed beams in targets which have non-uniform properties vary with positron energy and are different from the conventional positron source derived lifetime values in these targets.

  16. Resolvability of positron decay channels

    SciTech Connect

    Fluss, M.J.; Howell, R.H.; Rosenberg, I.J.; Meyer, P.

    1985-03-07

    Many data analysis treatments of positron experiments attempt to resolve two or more positron decay or exist channels which may be open simultaneously. Examples of the need to employ such treatments of the experimental results can be found in the resolution of the constituents of a defect ensemble, or in the analysis of the complex spectra which arise from the interaction of slow positrons at or near the surfaces of solids. Experimental one- and two-dimensional angular correlation of annihilation radiation experiments in Al single crystals have shown that two defect species (mono- and divacancies) can be resolved under suitable conditions. Recent experiments at LLNL indicate that there are a variety of complex exit channels open to positrons interacting at surfaces, and ultimely these decay channels must also be suitably resolved from one another. 6 refs., 4 figs.

  17. High Power Polarized Positron Source

    NASA Astrophysics Data System (ADS)

    Mikhailichenko, Alexander

    2009-09-01

    We discuss the basics of polarized positron production by low energy polarized electrons. Efficiency of conversion ˜0.1-1% might be interesting for the Continuous Electron Beam Accelerator Facility (CEBAF) and the International Linear Collider (ILC).

  18. Positrons from accelerated particle interactions

    NASA Technical Reports Server (NTRS)

    Kozlovsky, B.; Lingenfelter, R. E.; Ramaty, R.

    1987-01-01

    Positron production from the decay of radioactive nuclei produced in nuclear interactions of accelerated particles is treated in detail. Laboratory data as well as theoretical considerations are used to construct energy-dependent cross sections for the production of a large number of radioactive positron emitters resulting from proton and alpha-particle interactions with ambient cosmic matter. Using these cross sections, positron production rates are calculated for a variety of energetic particle spectra, assuming solar abundances for both the energetic particles and the ambient medium. These results can be used for the study of astrophysical sites which emit annihilation radiation. In particular, the results have been applied to solar flares, where the observed 0.511 MeV line is shown to be due to positrons resulting from accelerated particle reactions.

  19. Analysis on linac quadrupole misalignment in FACET commissioning 2012

    SciTech Connect

    Sun, Yipeng; /SLAC

    2012-07-05

    In this note, the analysis on linac quadrupole misalignment is presented for the FACET linac section LI05-09 plus LI11-19. The effectiveness of the beam-based alignment technique is preliminarily confirmed by the measurement. Beam-based alignment technique was adopted at SLAC linac since SLC time. Here the beam-based alignment algorithms are further developed and applied in the FACET commissioning during 2012 run.

  20. SNS LINAC Wire Scanner System : Signal Levels and Accuracy.

    SciTech Connect

    Plum, M. A.; Christensen, W.; Myer, R. E.; Rose, C. R.

    2002-01-01

    The linac wire scanner system for the Spallation Neutron Source (SNS) at Oak Ridge, TN, USA, calls for 5 units in the medium energy beam transport (MEBT), 5 in the drift tube linac (DTL), and 10 in the coupled cavity linac (CCL). In this paper we present expected signal levels and an analysis of the error in the beam size measurement as functions of wire position and electrical signal errors.

  1. Modelling Positron Interactions with Matter

    NASA Astrophysics Data System (ADS)

    Garcia, G.; Petrovic, Z.; White, R.; Buckman, S.

    2011-05-01

    In this work we link fundamental measurements of positron interactions with biomolecules, with the development of computer codes for positron transport and track structure calculations. We model positron transport in a medium from a knowledge of the fundamental scattering cross section for the atoms and molecules comprising the medium, combined with a transport analysis based on statistical mechanics and Monte-Carlo techniques. The accurate knowledge of the scattering is most important at low energies, a few tens of electron volts or less. The ultimate goal of this work is to do this in soft condensed matter, with a view to ultimately developing a dosimetry model for Positron Emission Tomography (PET). The high-energy positrons first emitted by a radionuclide in PET may well be described by standard formulas for energy loss of charged particles in matter, but it is incorrect to extrapolate these formulas to low energies. Likewise, using electron cross-sections to model positron transport at these low energies has been shown to be in serious error due to the effects of positronium formation. Work was supported by the Australian Research Council, the Serbian Government, and the Ministerio de Ciencia e Innovación, Spain.

  2. Beam position correction in the Fermilab linac

    SciTech Connect

    Junck, K.L.; McCrory, E.

    1994-08-01

    Orbit correction has long been an essential feature of circular accelerators, storage rings, multipass linacs, and linear colliders. In a drift tube linear accelerator (DTL) such as the H- Linac at Fermilab, beam position monitors (BPMs) and dipole corrector magnets can only be located in between accelerating tanks. Within a tank many drift tubes (from 20 to 60) each house a quadrupole magnet to provide strong transverse focusing of the beam. With good alignment of the drift tubes and quadrupoles and a sufficiently large diameter for the drift tubes, beam position is not typically a major concern. In the Fermilab DTL, 95% of the beam occupies only 35% of the available physical aperture (4.4 cm). The recent upgrade of the Fermilab Linac from a final energy of 200 MeV to 400 MeV has been achieved by replacing four 201.25 MHz drift tube linac tanks with seven 805 MHz side-coupled cavity modules (the high energy portion of the linac or HEL). In order to achieve this increase in energy within the existing enclosure, an accelerating gradient is required that is a factor of 3 larger than that found in the DTL. This in turn required that the physical aperture through which the beam must pass be significantly reduced. In addition, the lattice of the side-coupled structure provides significantly less transverse focusing than the DTL. Therefore in the early portion of the HEL the beam occupies over 95% of the available physical aperture (3.0 cm). In order to prevent beam loss and the creation of excess radiation, the ability to correct beam position throughout the HEL is of importance. An orbit smoothing algorithm commonly used in the correction of closed orbits of circular machines has been implemented to achieve a global least-squares minimization of beam position errors. In order to accommodate several features of this accelerator a refinement in the algorithm has been made to increase its robustness and utilize correctors of varying strengths.

  3. Beam position correction in the Fermilab Linac

    NASA Astrophysics Data System (ADS)

    Junck, K. L.; McCrory, E.

    1994-08-01

    Orbit correction has long been an essential feature of circular accelerators, storage rings, multipass linacs, and linear colliders. In a drift tube linear accelerator (DTL) such as the H- Linac at Fermilab, beam position monitors (BPMs) and dipole corrector magnets can only be located in between accelerating tanks. Within a tank many drift tubes (from 20 to 60) each house a quadrupole magnet to provide strong transverse focusing of the beam. With good alignment of the drift tubes and quadrupoles and a sufficiently large diameter for the drift tubes, beam position is not typically a major concern. In the Fermilab DTL, 95 percent of the beam occupies only 35 percent of the available physical aperture (4.4 cm). The recent upgrade of the Fermilab Linac from a final energy of 200 MeV to 400 MeV has been achieved by replacing four 201.25 MHz drift tube linac tanks with seven 805 MHz side-coupled cavity modules (the high energy portion of the linac or HEL). In order to achieve this increase in energy within the existing enclosure, an accelerating gradient is required that is a factor of 3 larger than that found in the DTL. This in turn required that the physical aperture through which the beam must pass be significantly reduced. In addition, the lattice of the side-coupled structure provides significantly less transverse focusing than the DTL. Therefore in the early portion of the HEL the beam occupies over 95 percent of the available physical aperture (3.0 cm). In order to prevent beam loss and the creation of excess radiation, the ability to correct beam position throughout the HEL is of importance. An orbit smoothing algorithm commonly used in the correction of closed orbits of circular machines has been implemented to achieve a global least-squares minimization of beam position errors. In order to accommodate several features of this accelerator a refinement in the algorithm has been made to increase its robustness and utilize correctors of varying strengths.

  4. The Transverse Linac Optics Design in Multi-pass ERL

    SciTech Connect

    Hao, Y.; Kewisch, J.; Litvinenko,V.; Pozdeyev, E.; Ptitsyn, V.; Trbojevic, D.; Tsoupas, N.

    2010-05-23

    In this paper, we analyzed the linac optics design requirement for a multi-pass energy recovery linac (ERL) for arbitrary number of linacs. A set of general formula of constrains for the 2-D transverse matrix is derived to ensure design optics acceptance matching throughout the entire accelerating and decelerating process. Meanwhile, the rest free parameters can be adjusted for fulfilling other requirements or optimization purpose. As an example, we design the linac optics for the future MeRHIC (Medium Energy eRHIC) project and show the optimization for small {beta} function.

  5. SIMULATIONS OF A MUON LINAC FOR A NEUTRINO FACTORY

    SciTech Connect

    Kevin Beard, Alex Bogacz ,Slawomir Bogacz, Vasiliy Morozov, Yves Roblin

    2011-04-01

    The Neutrino Factory baseline design involves a complex chain of accelerators including a single-pass linac, two recirculating linacs and an FFAG. The first linac follows the capture and bunching section and accelerates the muons from about 244 to 900 MeV. It must accept a high emittance beam about 30 cm wide with a 10% energy spread. This linac uses counterwound, shielded superconducting solenoids and 201 MHz superconducting cavities. Simulations have been carried out using several codes including Zgoubi, OptiM, GPT, Elegant and G4beamline, both to determine the optics and to estimate the radiation loads on the elements due to beam loss and muon decay.

  6. Designs for a Linac-Ring LHeC

    SciTech Connect

    Zimmermann, Frank; Bruning, Oliver; Ciapala, Edmond; Haug, Friedrich; Osborne, John; Schulte, Daniel; Sun, Yipeng; Tomas, Rogelio; Adolphsen, Chris; Calaga, Rama; Litvinenko, Vladimir; Chattopadhyay, Swapan; Dainton, John; Klein, Max; Eide, Anders; /Paris U., VI-VII

    2012-06-21

    We consider three scenarios for the recirculating electron linear accelerator (RLA) of a linac-ring type electron-proton collider based on the LHC (LHeC): (i) a pulsed linac with a final beam energy of 60 GeV ['p-60'], (ii) a higher luminosity configuration with two cw linacs and energy-recovery (ERL) also at 60 GeV ['erl'], and (iii) a high energy option using a pulsed linac with 140-GeV final energy ['p-140']. We discuss parameters, synchrotron radiation, footprints, and performance for the three scenarios.

  7. Electron transport of a Linac Coherent Light Source (LCLS) using the SLAC linac

    SciTech Connect

    Bane, K.L.; Raubenheimer, T.O.; Seeman, J.T.

    1993-05-01

    A linac configuration providing a low emittance high peak current electron beam is under study for a potential Linac Coherent Light Source (LCLS) based on the SLAC accelerator. The parameters of the final electron bunch are nearing the technological limits of present accelerators in both transverse and longitudinal phase space. In this note we describe a layout of the RF gun, linac, and bunch compressors to deliver the required bunch properties. We consider a bunch that is generated by an rf gun and accelerated to 7 GeV in 900 m of SLAC linac structure before it enters the wiggler. We assume that the rf gun generates a gaussian beam with an energy of 10 MeV, a population N = 6 {times} 10{sup 9}e{sup {minus}}, an rms length {sigma}{sub z} = 0.5 mm, an rms energy spread {sigma}{sub {delta}} = 0.2%, and normalized rms emittances {gamma}{epsilon}{sub x,y} = 3 mm-mrad. At the end of the linac, we require that the peak current {cflx I} {approx_gt} 2.5 kA and the peak-to-peak energy spread {Delta}{delta} {approx_lt} 0.2%. To obtain the required high peak current, we need to compress the bunch length by a factor greater than 10. In deciding at what position in the linac to compress we need to consider three issues: the longitudinal wakefield in the linac, this increases the beam`s energy spread and is harder to compensate with short bunches, the transverse wakefield and rf deflections in the linac, these increase the transverse emittance of the beam and are more severe for long bunches, and the effects of phase and current jitter which will change the bunch length and therefore the peak current of the beam. In this paper, we will describe how we compress the bunch to meet these three criteria. Then, we will briefly describe the bunch compressor optics and finally we will mention some details specific to the SLAC site.

  8. Interdigital H -mode drift-tube linac design with alternative phase focusing for muon linac

    NASA Astrophysics Data System (ADS)

    Otani, M.; Mibe, T.; Yoshida, M.; Hasegawa, K.; Kondo, Y.; Hayashizaki, N.; Iwashita, Y.; Iwata, Y.; Kitamura, R.; Saito, N.

    2016-04-01

    We have developed an interdigital H-mode (IH) drift-tube linac (DTL) design with an alternative phase focusing (APF) scheme for a muon linac, in order to measure the anomalous magnetic moment and electric dipole moment (EDM) of muons at the Japan Proton Accelerator Research Complex (J-PARC). The IH-DTL accelerates muons from β =v /c =0.08 to 0.28 at an operational frequency of 324 MHz. The output beam emittances are calculated as 0.315 π and 0.195 π mm mrad in the horizontal and vertical directions, respectively, which satisfies the experimental requirement.

  9. Linac Coherent Light Source (LCLS) at 2--4 nm using the SLAC linac

    SciTech Connect

    Seeman, J.T.; Bane, K.; Boyce, R.; Loew, G.; Morton, P.; Nuhn, H.D.; Paterson, J.; Pianetta, P.; Raubenheimer, T.; Tatchyn, R.; Vylet, V.; Winick, H.; Pellegrini, C.; Rosenzweig, J.; Travish, G.; Prosnitz, D.; Scharlemann, E.T.; Halbach, K.; Kim, K.J.; Xie, M.

    1993-08-01

    The authors describe the possible use of the SLAC linac to drive a unique, powerful, short wavelength Linac Coherent Light Source (LCLS). Using the FEL principle, lasing is achieved in a single pass of a high peak current electron beam through a long undulator by self-amplified-spontaneous-emission (SASE). The main components are a high-brightness electron RF gun with a photocathode, two electron bunch length compressors, the existing SLAC linac, beam diagnostics, and a long undulator combined with a FODO quadrupole focusing system. The RF gun, to be installed about 1 km from the end of the SLAC linac, would produce a single bunch of 6 x 10{sup 9} electrons with an invariant emittance of about 3 mm-mrad and a bunch length of about 500 {mu}m. That bunch is then accelerated to 100 MeV and compressed to a length of about 200 {mu}m. The main SLAC linac accelerates the bunch to 2 GeV were a second bunch compressor reduces the length to 30--40 {mu}m and produces a peak current of 2--3 kA. The bunch is then accelerated to 7--8 GeV and transported to a 50--70 m long undulator. Using electrons below 8 GeV, the undulator could operate at wavelengths down to 2 nm, producing about 10 GW peak power in sub-ps light pulses. At a linac repetition rate of 120 Hz, the average power is about 1 W. Linac operation at lower beam energies provides longer wavelength radiation. After the undulator, the beam is deposited in a dump. The LCLS light pulses are then distributed to multiple user stations using grazing incident mirrors. Length compression, emittance control, phase stability, FEL design criteria, and parameter tolerances are discussed. A demonstration experiment is also described which uses the SLAC linac and (possibly) the PALADIN undulator to study SASE to power saturation at wavelengths of 40--360 nm.

  10. Method for photon activation positron annihilation analysis

    DOEpatents

    Akers, Douglas W.

    2006-06-06

    A non-destructive testing method comprises providing a specimen having at least one positron emitter therein; determining a threshold energy for activating the positron emitter; and determining whether a half-life of the positron emitter is less than a selected half-life. If the half-life of the positron emitter is greater than or equal to the selected half-life, then activating the positron emitter by bombarding the specimen with photons having energies greater than the threshold energy and detecting gamma rays produced by annihilation of positrons in the specimen. If the half-life of the positron emitter is less then the selected half-life, then alternately activating the positron emitter by bombarding the specimen with photons having energies greater then the threshold energy and detecting gamma rays produced by positron annihilation within the specimen.

  11. High-intensity positron microprobe at the Thomas Jefferson National Accelerator Facility

    SciTech Connect

    Golge, S. Vlahovic, B.; Wojtsekhowski, B.

    2014-06-21

    We present a conceptual design for a novel continuous wave electron-linac based high-intensity high-brightness slow-positron production source with a projected intensity on the order of 10{sup 10 }e{sup +}/s. Reaching this intensity in our design relies on the transport of positrons (T{sub +} below 600 keV) from the electron-positron pair production converter target to a low-radiation and low-temperature area for moderation in a high-efficiency cryogenic rare gas moderator, solid Ne. This design progressed through Monte Carlo optimizations of: electron/positron beam energies and converter target thickness, transport of the e{sup +} beam from the converter to the moderator, extraction of the e{sup +} beam from the magnetic channel, a synchronized raster system, and moderator efficiency calculations. For the extraction of e{sup +} from the magnetic channel, a magnetic field terminator plug prototype has been built and experimental results on the effectiveness of the prototype are presented. The dissipation of the heat away from the converter target and radiation protection measures are also discussed.

  12. High-intensity positron microprobe at the Thomas Jefferson National Accelerator Facility

    NASA Astrophysics Data System (ADS)

    Golge, S.; Vlahovic, B.; Wojtsekhowski, B.

    2014-06-01

    We present a conceptual design for a novel continuous wave electron-linac based high-intensity high-brightness slow-positron production source with a projected intensity on the order of 1010 e+/s. Reaching this intensity in our design relies on the transport of positrons (T+ below 600 keV) from the electron-positron pair production converter target to a low-radiation and low-temperature area for moderation in a high-efficiency cryogenic rare gas moderator, solid Ne. This design progressed through Monte Carlo optimizations of: electron/positron beam energies and converter target thickness, transport of the e+ beam from the converter to the moderator, extraction of the e+ beam from the magnetic channel, a synchronized raster system, and moderator efficiency calculations. For the extraction of e+ from the magnetic channel, a magnetic field terminator plug prototype has been built and experimental results on the effectiveness of the prototype are presented. The dissipation of the heat away from the converter target and radiation protection measures are also discussed.

  13. Optical emission spectroscopy of the Linac4 and superconducting proton Linac plasma generators.

    PubMed

    Lettry, J; Fantz, U; Kronberger, M; Kalvas, T; Koivisto, H; Komppula, J; Mahner, E; Schmitzer, C; Sanchez, J; Scrivens, R; Midttun, O; Myllyperkiö, P; O'Neil, M; Pereira, H; Paoluzzi, M; Tarvainen, O; Wünderlich, D

    2012-02-01

    CERN's superconducting proton Linac (SPL) study investigates a 50 Hz high-energy, high-power Linac for H(-) ions. The SPL plasma generator is an evolution of the DESY ion source plasma generator currently operated at CERN's Linac4 test stand. The plasma generator is a step towards a particle source for the SPL, it is designed to handle 100 kW peak RF-power at a 6% duty factor. While the acquisition of an integrated hydrogen plasma optical spectrum is straightforward, the measurement of a time-resolved spectrum requires dedicated amplification schemes. The experimental setup for visible light based on photomultipliers and narrow bandwidth filters and the UV spectrometer setup are described. The H(α), H(β), and H(γ) Balmer line intensities, the Lyman band and alpha transition were measured. A parametric study of the optical emission from the Linac4 ion source and the SPL plasma generator as a function of RF-power and gas pressure is presented. The potential of optical emission spectrometry coupled to RF-power coupling measurements for on-line monitoring of short RF heated hydrogen plasma pulses is discussed. PMID:22380238

  14. Design of the SLC damping ring to linac transport lines

    SciTech Connect

    Fieguth, T.H.; Murray, J.J.

    1983-07-01

    The first and second order optics for the damping ring to linac transport line are designed to preserve the damped transverse emittance while simultaneously compressing the bunch length of the beam to that length required for reinjection into the linac. This design, including provisions for future control of beam polarization, is described.

  15. MEIC Proton Beam Formation with a Low Energy Linac

    SciTech Connect

    Zhang, Yuhong

    2015-09-01

    The MEIC proton and ion beams are generated, accumulated, accelerated and cooled in a new green-field ion injector complex designed specifically to support its high luminosity goal. This injector consists of sources, a linac and a small booster ring. In this paper we explore feasibility of a short ion linac that injects low-energy protons and ions into the booster ring.

  16. Numerical simulation of coupler cavities for linacs

    SciTech Connect

    Ng, C.K.; Derutyer, H.; Ko, K.

    1993-04-01

    We present numerical procedures involved in the evaluation of the performance of coupler cavities for linacs. The MAFIA code is used to simulate an X-Band accelerator section in the time domain. The input/output coupler cavities for the structure arc of the symmetrical double-input design. We calculate the transmission properties of the coupler and compare the results with measurements. We compare the performance of the symmetrical double-input design with that of the conventional single-input type by evaluating the field amplitude and phase asymmetries. We also evaluate the peak field gradient in the computer.

  17. High density harp for SSCL linac

    SciTech Connect

    Fritsche, C.T.; Krogh, M.L.; Crist, C.E.

    1993-05-01

    AlliedSignal Inc., Kansas City Division, and the Superconducting Super Collider Laboratory (SSCL) are collaboratively developing a high density harp for the SSCL linac. This harp is designed using hybrid microcircuit (HMC) technology to obtain a higher wire density than previously available. The developed harp contains one hundred twenty-eight 33-micron-diameter carbon wires on 0.38-mm centers. The harp features an onboard broken wire detection circuit. Carbon wire preparation and attachment processes were developed. High density surface mount connectors were located. The status of high density harp development will be presented along with planned future activities.

  18. An overview of LINAC ion sources

    SciTech Connect

    Keller, Roderich

    2008-01-01

    This paper discusses ion sources used in high-duty-factor proton and H{sup -} Linacs as well as in accelerators utilizing multi-charged heavy ions, mostly for nuclear physics applications. The included types are Electron Cyclotron Resonance (ECR) sources as well as filament and rf driven multicusp sources. The paper does not strive to attain encyclopedic character but rather to highlight major lines of development, peak performance parameters and type-specific limitations and problems of these sources. The main technical aspects being discussed are particle feed, plasma generation and ion production by discharges, and plasma confinement.

  19. Superconducting radiofrequency linac development at Fermilab

    SciTech Connect

    Holmes, Stephen D.; /Fermilab

    2009-10-01

    As the Fermilab Tevatron Collider program draws to a close, a strategy has emerged of an experimental program built around the high intensity frontier. The centerpiece of this program is a superconducting H- linac that will support world leading programs in long baseline neutrino experimentation and the study of rare processes. Based on technology shared with the International Linear Collider, Project X will provide multi-MW beams at 60-120 GeV from the Main Injector, simultaneous with very high intensity beams at lower energies. Project X also supports development of a Muon Collider as a future facility at the energy frontier.

  20. Laser system for a subpicosecond electron linac.

    SciTech Connect

    Crowell, R. A.

    1998-09-25

    At the Argonne Chemistry Division efforts are underway to develop a sub-picosecond electron beam pulse radiolysis facility for chemical studies. The target output of the accelerator is to generate electron pulses that can be adjusted from 3nC in .6ps to 100nC in 45ps. In conjunction with development of the accelerator a state-of-the-art ultrafast laser system is under construction that will drive the linac's photocathode and provide probe pulses that are tunable from the UV to IR spectral regions.

  1. Physics design of front ends for superconducting ion linacs

    SciTech Connect

    Ostroumov, P.N.; Carneiro, J.P.; /Fermilab

    2009-01-01

    Superconducting (SC) technology is the only option for CW linacs and is also an attractive option for pulsed linacs. SC cavities are routinely used for proton and H{sup -} beam acceleration above 185 MeV. Successful development of SC cavities covering the lower velocity range (down to 0.03c) is a very strong basis for the application of SC structures in the front ends of high energy linacs. Lattice design and related high-intensity beam physics issues in a {approx}400 MeV linac that uses SC cavities will be presented in this talk. In particular, axially-symmetric focusing by SC solenoids provides strong control of beam space-charge and a compact focusing lattice. As an example, we discuss the SC front-end of the H{sup -} linac for the FNAL Proton Driver.

  2. 10MeV 25KW industrial electron LINAC

    NASA Astrophysics Data System (ADS)

    Kamino, Y.

    1998-06-01

    A 10MeV 25KW plus class electron LINAC was developed for sterilisation of medical devices. The LINAC composed of a standing wave type single cavity prebuncher and a 2m electro-plated travelling wave guide uses a 5MW 2856MHz pulse klystron as an RF source and provides 25KW beam power at the Ti alloy beam window stably after the energy analysing magnet with 10MeV plus-minus 1 MeV energy slit. The practical maximum beam power reached 29 KW and this demonstrated the LINAC as one of the most powerful S-band electron LINACs in the world. The control of the LINAC is fully automated and the "One-Button Operation" is realised, which is valuable for easy operation as a plant system. 2 systems have been delivered and are being operated stably.

  3. Positron emitter labeled enzyme inhibitors

    DOEpatents

    Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

    1987-05-22

    This invention involved a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide in activators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography. 2 figs.

  4. Positron emitter labeled enzyme inhibitors

    DOEpatents

    Fowler, Joanna S.; MacGregor, Robert R.; Wolf, Alfred P.; Langstrom, Bengt

    1990-01-01

    This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.

  5. Positron-alkali atom scattering

    NASA Technical Reports Server (NTRS)

    Mceachran, R. P.; Horbatsch, M.; Stauffer, A. D.; Ward, S. J.

    1990-01-01

    Positron-alkali atom scattering was recently investigated both theoretically and experimentally in the energy range from a few eV up to 100 eV. On the theoretical side calculations of the integrated elastic and excitation cross sections as well as total cross sections for Li, Na and K were based upon either the close-coupling method or the modified Glauber approximation. These theoretical results are in good agreement with experimental measurements of the total cross section for both Na and K. Resonance structures were also found in the L = 0, 1 and 2 partial waves for positron scattering from the alkalis. The structure of these resonances appears to be quite complex and, as expected, they occur in conjunction with the atomic excitation thresholds. Currently both theoretical and experimental work is in progress on positron-Rb scattering in the same energy range.

  6. Instrumentation in positron emission tomography

    SciTech Connect

    Not Available

    1988-03-11

    Positron emission tomography (PET) is a three-dimensional medical imaging technique that noninvasively measures the concentration of radiopharmaceuticals in the body that are labeled with positron emitters. With the proper compounds, PET can be used to measure metabolism, blood flow, or other physiological values in vivo. The technique is based on the physics of positron annihilation and detection and the mathematical formulations developed for x-ray computed tomography. Modern PET systems can provide three-dimensional images of the brain, the heart, and other internal organs with resolutions on the order of 4 to 6 mm. With the selectivity provided by a choice of injected compounds, PET has the power to provide unique diagnostic information that is not available with any other imaging modality. This is the first five reports on the nature and uses of PET that have been prepared for the American Medical Association's Council on Scientific Affairs by an authoritative panel.

  7. Positron emitter labeled enzyme inhibitors

    SciTech Connect

    Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.; Langstrom, B.

    1990-04-03

    This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.

  8. Instrumentation for positron emission tomography.

    PubMed

    Budinger, T F; Derenzo, S E; Huesman, R H

    1984-01-01

    Positron emission tomography with a spatial resolution of 2 mm full width at half maximum for quantitation in regions of interest 4 mm in diameter will become possible with the development of detectors that achieve ultrahigh resolution. Improved resolution will be possible using solid-state photodetectors for crystal identification or photomultiplier tubes with many small electron multipliers . Temporal resolution of 2 seconds and gating of cyclic events can be accomplished if statistical requirements are met. The major physical considerations in achieving high-resolution positron emission tomography are the degradation in resolution resulting from positron range, emission angle, parallax error, detector sampling density, the sensitivity of various detector materials and packing schemes, and the trade off between temporal resolution and statistical accuracy. The accuracy of data required for physiological models depends primarily on the fidelity of spatial sampling independent of statistical constraints. PMID:6611124

  9. Positron spectroscopy for materials characterization

    SciTech Connect

    Schultz, P.J.; Snead, C.L. Jr.

    1988-01-01

    One of the more active areas of research on materials involves the observation and characterization of defects. The discovery of positron localization in vacancy-type defects in solids in the 1960's initiated a vast number of experimental and theoretical investigations which continue to this day. Traditional positron annihilation spectroscopic techniques, including lifetime studies, angular correlation, and Doppler broadening of annihilation radiation, are still being applied to new problems in the bulk properties of simple metals and their alloys. In addition new techniques based on tunable sources of monoenergetic positron beams have, in the last 5 years, expanded the horizons to studies of surfaces, thin films, and interfaces. In the present paper we briefly review these experimental techniques, illustrating with some of the important accomplishments of the field. 40 refs., 19 figs.

  10. E166: Polarized Positrons & Polarimetry

    SciTech Connect

    Schuler, K.Peter; /DESY

    2011-12-06

    A proof-of-principle experiment has been carried out in the Final Focus Test Beam (FFTB) at Stanford Linear Accelerator Center (SLAC) to demonstrate production of polarized positrons in a manner suitable for implementation at the International Linear Collider (ILC). A helical undulator of 2.54 mm period and 1 -m length produced circularly polarized photons with a first harmonic endpoint energy of 8 MeV when traversed by a 46.6 GeV electron beam. The polarized photons were converted to polarized positrons in a 0.2-radiation-length tungsten target. The polarization of these positrons was measured using a Compton transmission polarimeter to have peak value in excess of 80%.

  11. Particle physics. Positrons ride the wave

    SciTech Connect

    Piot, Philippe

    2015-08-26

    Here, experiments reveal that positrons — the antimatter equivalents of electrons — can be rapidly accelerated using a plasma wave. The findings pave the way to high-energy electron–positron particle colliders.

  12. Particle physics. Positrons ride the wave

    SciTech Connect

    Piot, Philippe

    2015-08-26

    Experiments reveal that positrons — the antimatter equivalents of electrons — can be rapidly accelerated using a plasma wave. The findings pave the way to high-energy electron–positron particle colliders.

  13. Short wavelength FELs using the SLAC linac

    SciTech Connect

    Winick, H.; Bane, K.; Boyce, R.

    1993-08-01

    Recent technological developments have opened the possibility to construct a device which we call a Linac Coherent Light Source (LCLS); a fourth generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much aborter wavelength than the 240 mn that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3-100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by Self-Amplified-Spontaneous-Emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops.

  14. Features Of The J-PARC Linac

    SciTech Connect

    Kobayashi, Tetsuya

    2011-06-01

    Japan Proton Accelerator Research Complex (J-PARC) will be one of the highest intensity proton accelerators in the world aiming to realize 1 MW class of the beam power. The accelerator consists of a 400-MeV linac, a 3-GeV rapid-cycling synchrotron (RCS) and a main ring synchrotron (MR), and the accelerated beam is applied to several experimental facilities. The linac, which is the injector for the RCS, has about 50 cavity modules to accelerate the beam up to 400 MeV. The acceleration field error in all of them should be within {+-}1% in amplitude and {+-}1 degree in phase because the momentum spread of the RCS injection beam is required to be within 0.1%. For the cavity field stabilization, a high-stable optical signal distribution system is used as the RF reference, and sophisticated digital feedback and feed-forward system is working well in the low level RF control system. Consequently the providing beam to the RCS is very stable, and the beam commissioning and the experiments of the application facilities have been progressed steadily.

  15. SSC Linac Beam Position Monitor System

    NASA Astrophysics Data System (ADS)

    Aiello, G. Roberto; Jones, Alan A.; Mills, Mark R.

    1994-10-01

    The Superconducting Super Collider (SSC), Linac Beam Position Monitor System is designed to measure beam position and phase. Forty-three monitors will be installed in the Linac and Transfer Line. The position measurement provides information on the transverse beam position in the beam pipe with respect to a mechanical reference. The phase measurement provides information on the difference between the longitudinal phase of the beam and the radio frequency reference signal (rf reference), to be used for phase scanning and time of flight measurement. The system design and the prototypes are complete, and the series is under fabrication. The signals to be processed are extracted from four striplines, down-converted to a convenient intermediate frequency and fed into position and phase electronics. The position electronics is realized with the log-ratio technique, and the phase electronics uses a new digital technique that overcomes most of the problems of existing systems. Both position and phase analog electronics are mounted on identical VXI motherboards, containing analog-to-digital converters (ADC's) and digital circuitry.

  16. Linac-driven spallation-neutron source

    SciTech Connect

    Jason, A.J.

    1995-05-01

    Strong interest has arisen in accelerator-driven spallation-neutron sources that surpass existing facilities (such as ISIS at Rutherford or LANSCE at Los Alamos) by more than an order of magnitude in beam power delivered to the spallation target. The approach chosen by Los Alamos (as well as the European Spallation Source) provides the full beam energy by acceleration in a linac as opposed to primary acceleration in a synchrotron or other circular device. Two modes of neutron production are visualized for the source. A short-pulse mode produces 1 MW of beam power (at 60 pps) in pulses, of length less than 1 ms, by compression of the linac macropulse through multi-turn injection in an accumulator ring. A long-pulse mode produces a similar beam power with 1-ms-long pulses directly applied to a target. This latter mode rivals the performance of existing reactor facilities to very low neutron energies. Combination with the short-pulse mode addresses virtually all applications.

  17. BEAM LOSS MECHANISMS IN HIGH INTENSITY LINACS

    SciTech Connect

    Plum, Michael A

    2012-01-01

    In the present operation of the Oak Ridge Spallation Neutron Source, 60-Hz, 825-us H beam pulses are accelerated to 910 MeV, and then compressed to less than a microsecond in the storage ring, to deliver 1 MW of beam power to the spallation target. The beam loss in the superconducting portion of the linac is higher than expected, and it has shown a surprising counter-intuitive correlation with quadrupole magnetic fields, with a loss minimum occurring when the quadrupoles are set to approximately half their design values. This behavior can now be explained by a recent set of experiments that show the beam loss is primarily due to intra-beam stripping. Beam halo is another important beam loss contributor, and collimation in the 2.5 MeV Medium Energy Beam Transport has proven to be an effective mitigation strategy. In this presentation, we will summarize these and other beam loss mechanisms that are important for high intensity linacs.

  18. RIA Superconducting Drift Tube Linac R & D

    SciTech Connect

    J. Popielarski; J. Bierwagen; S. Bricker; C. Compton; J. DeLauter; P. Glennon; T. Grimm; W. Hartung; D. Harvell; M. Hodek; M. Johnson; F. Marti; P. Miller; A. Moblo; D. Norton; L. Popielarski; J. Wlodarczak; R. C. York; A. Zeller

    2009-05-22

    Cavity and cryomodule development work for a superconducting ion linac has been underway for several years at the National Superconducting Cyclotron Laboratory. The original application of the work was the proposed Rare Isotope Accelerator. At present, the work is being continued for use with the Facility for Rare Isotope Beams (FRIB). The baseline linac for FRIB requires 4 types of superconducting cavities to cover the velocity range needed to accelerate an ion beam to 200 MeV/u: 2 types of quarter-wave resonator (QWR) and 2 types of half-wave resonator (HWR). Superconducting solenoids are used for focussing. Active and passive shielding is required to ensure that the solenoids’ field does not degrade the cavity performance. First prototypes of both QWR types and one HWR type have been fabricated and tested. A prototype solenoid has been procured and tested. A test cryomodule has been fabricated and tested. The test cryomodule contains one QWR, one HWR, one solenoid, and one super-ferric quadrupole. This report covers the design, fabrication, and testing of this cryomodule

  19. Linac Coherent Light Source - Status and Prospects

    SciTech Connect

    Galayda, John N.; /SLAC

    2005-11-09

    The Linac Coherent Light Source (LCLS) Project will be an x-ray free-electron laser. It is intended to produce pulses of 800-8,000 eV photons. Each pulse, produced with a repetition frequency of up to 120 Hz, will provide >10{sup 12} photons within a duration of less than 200 femtoseconds. The project employs the last kilometer of the SLAC linac to provide a low-emittance electron beam in the energy range 4-14 GeV to a single undulator. Two experiment halls, located 100m and 350m from the undulator exit, will house six experiment stations for research in atomic/molecular physics, pump-probe dynamics of materials and chemical processes, x-ray imaging of clusters and complex molecules, and plasma physics. Engineering design activities began in 2003, and the project is to be completed in March 2009. The project design permits straightforward expansion of the LCLS to multiple undulators.

  20. SSC Linac Beam Position Monitor System

    SciTech Connect

    Aiello, G.R.; Jones, A.A.; Mills, M.R. )

    1994-10-10

    The Superconducting Super Collider (SSC), Linac Beam Position Monitor System is designed to measure beam position and phase. Forty-three monitors will be installed in the Linac and Transfer Line. The position measurement provides information on the transverse beam position in the beam pipe with respect to a mechanical reference. The phase measurement provides information on the difference between the longitudinal phase of the beam and the radio frequency reference signal (rf reference), to be used for phase scanning and time of flight measurement. The system design and the prototypes are complete, and the series is under fabrication. The signals to be processed are extracted from four striplines, down-converted to a convenient intermediate frequency and fed into position and phase electronics. The position electronics is realized with the log-ratio technique, and the phase electronics uses a new digital technique that overcomes most of the problems of existing systems. Both position and phase analog electronics are mounted on identical VXI motherboards, containing analog-to-digital converters (ADC's) and digital circuitry.

  1. Electrostatic Nonplanar Positron-Acoustic Shock Waves in Superthermal Electron-Positron-Ion Plasmas

    NASA Astrophysics Data System (ADS)

    M. J., Uddin; M. S., Alam; A. A., Mamun

    2015-06-01

    The basic properties of the nonlinear propagation of the nonplanar (cylindrical and spherical) positron-acoustic (PA) shock waves (SHWs) in an unmagnetized electron-positron-ion (e-p-i) plasma containing immobile positive ions, mobile cold positrons, and superthermal (kappa distributed) hot positrons and electrons are investigated both analytically and numerically. The modified Burgers equation (mBE) is derived by using the reductive perturbation method. The basic features of PA SHWs are significantly modified by the cold positron kinematic viscosity (η), superthermal parameter of electrons (κe), superthermal parameter of hot positrons (κp), the ratio of the electron temperature to hot positron temperature (σ), the ratio of the electron number density to cold positron number density and the ratio of the hot positron number density to cold positron number density (μph). This study could be useful to identify the basic properties of nonlinear electrostatic disturbances in dissipative space and laboratory plasmas.

  2. 21 CFR 892.1110 - Positron camera.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Positron camera. 892.1110 Section 892.1110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1110 Positron camera. (a) Identification. A positron camera is a device intended to image...

  3. PHYSICS RESULTS OF THE NSLS-II LINAC FRONT END TEST STAND

    SciTech Connect

    Fliller R. P.; Gao, F.; Yang, X.; Rose, J.; Shaftan, T.; Piel, C

    2012-05-20

    The Linac Front End Test Stand (LFETS) was installed at the Source Development Laboratory (SDL) in the fall of 2011 in order to test the Linac Front End. The goal of these tests was to test the electron source against the specifications of the linac. In this report, we discuss the results of these measurements and the effect on linac performance.

  4. Computation of Normal Conducting and Superconducting Linear Accelerator (LINAC) Availabilities

    SciTech Connect

    Haire, M.J.

    2000-07-11

    A brief study was conducted to roughly estimate the availability of a superconducting (SC) linear accelerator (LINAC) as compared to a normal conducting (NC) one. Potentially, SC radio frequency cavities have substantial reserve capability, which allows them to compensate for failed cavities, thus increasing the availability of the overall LINAC. In the initial SC design, there is a klystron and associated equipment (e.g., power supply) for every cavity of an SC LINAC. On the other hand, a single klystron may service eight cavities in the NC LINAC. This study modeled that portion of the Spallation Neutron Source LINAC (between 200 and 1,000 MeV) that is initially proposed for conversion from NC to SC technology. Equipment common to both designs was not evaluated. Tabular fault-tree calculations and computer-event-driven simulation (EDS) computer computations were performed. The estimated gain in availability when using the SC option ranges from 3 to 13% under certain equipment and conditions and spatial separation requirements. The availability of an NC LINAC is estimated to be 83%. Tabular fault-tree calculations and computer EDS modeling gave the same 83% answer to within one-tenth of a percent for the NC case. Tabular fault-tree calculations of the availability of the SC LINAC (where a klystron and associated equipment drive a single cavity) give 97%, whereas EDS computer calculations give 96%, a disagreement of only 1%. This result may be somewhat fortuitous because of limitations of tabular fault-tree calculations. For example, tabular fault-tree calculations can not handle spatial effects (separation distance between failures), equipment network configurations, and some failure combinations. EDS computer modeling of various equipment configurations were examined. When there is a klystron and associated equipment for every cavity and adjacent cavity, failure can be tolerated and the SC availability was estimated to be 96%. SC availability decreased as

  5. PERFORMANCE OF THE DIAGNOSTICS FOR NSLS-II LINAC COMMISSIONING

    SciTech Connect

    Fliller III, R.; Padrazo, D.; Wang, G.M.; Heese, R.; Hseuh H.-C.; Johanson, M.; Kosciuk, B.N.; Pinayev, I.; Rose, J.; Shaftan, T.; Singh, O.

    2011-03-28

    The National Synchrotron Light Source II (NSLS-II) is a state of the art 3-GeV third generation light source currently under construction at Brookhaven National Laboratory. The NSLS-II injection system consists of a 200 MeV linac, a 3-GeV booster synchrotron and associated transfer lines. The transfer lines not only provide a means to deliver the beam from one machine to another, they also provide a suite of diagnostics and utilities to measure the properties of the beam to be delivered. In this paper we discuss the suite of diagnostics that will be used to commission the NSLS-II linac and measure the beam properties. The linac to booster transfer line can measure the linac emittance with a three screens measurement or a quadrupole scan. Energy and energy spread are measured in a dispersive section. Total charge and charge uniformity are measured with wall current monitors in the linac and transformers in the transfer line. We show that the performance of the diagnostics in the transfer line will be sufficient to ensure the linac meets its specifications and provides a means of trouble shooting and studying the linac in future operation.

  6. Positron-acoustic shock waves associated with cold viscous positron fluid in superthermal electron-positron-ion plasmas

    SciTech Connect

    Uddin, M. J. Alam, M. S.; Mamun, A. A.

    2015-06-15

    A theoretical investigation is made on the positron-acoustic (PA) shock waves (SHWs) in an unmagnetized electron-positron-ion plasma containing immobile positive ions, cold mobile positrons, and hot positrons and electrons following the kappa (κ) distribution. The cold positron kinematic viscosity is taken into account, and the reductive perturbation method is used to derive the Burgers equation. It is found that the viscous force acting on cold mobile positron fluid is a source of dissipation and is responsible for the formation of the PA SHWs. It is also observed that the fundamental properties of the PA SHWs are significantly modified by the effects of different parameters associated with superthermal (κ distributed) hot positrons and electrons.

  7. Positron-acoustic shock waves associated with cold viscous positron fluid in superthermal electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Uddin, M. J.; Alam, M. S.; Mamun, A. A.

    2015-06-01

    A theoretical investigation is made on the positron-acoustic (PA) shock waves (SHWs) in an unmagnetized electron-positron-ion plasma containing immobile positive ions, cold mobile positrons, and hot positrons and electrons following the kappa (κ) distribution. The cold positron kinematic viscosity is taken into account, and the reductive perturbation method is used to derive the Burgers equation. It is found that the viscous force acting on cold mobile positron fluid is a source of dissipation and is responsible for the formation of the PA SHWs. It is also observed that the fundamental properties of the PA SHWs are significantly modified by the effects of different parameters associated with superthermal (κ distributed) hot positrons and electrons.

  8. Simulation studies of the LAMPF proton linac

    SciTech Connect

    Garnett, R.W.; Gray, E.R.; Rybarcyk, L.J.; Wangler, T.P.

    1995-05-01

    The LAMPF accelerator consists of two 0.75-MeV injectors, one for H{sup +} and the other for H{sup {minus}}, a separate low-energy beam transport (LEBT) line for each beam species, a 0.75 to 100-MeV drift-tube linac (DTL) operating at 201.25-MHz, a 100-MeV transition region (TR), and a 100 to 800-MeV side-coupled linac (SCL) operating at 805-MHz. Each LEBT line consists of a series of quadrupoles to transport and transversely match the beam. The LEBT also contains a prebuncher, a main buncher, and an electrostatic deflector. The deflector is used to limit the fraction of a macropulse which is seen by the beam diagnostics throughout the linac. The DTL consists of four rf tanks and uses singlet FODO transverse focusing. The focusing period is doubled in the last two tanks by placing a quadrupole only in every other drift-tube. Doublet FDO transverse focusing is used in the SCL. The TR consists of separate transport lines for the H{sup +} and H{sup {minus}} beams. The pathlengths for the two beams differ, by introducing bends, so as to delay arrival of one beam relative to the other and thereby produce the desired macropulse time structure. Peak beam currents typically range from 12 to 18-mA for varying macropulse lengths which give an average beam current of 1-mA. The number of particles per bunch is of the order 10{sup 8}. The work presented here is an extension of previous work. The authors have attempted to do a more complete simulation by including modeling of the LEBT. No measurements of the longitudinal structure of the beam, except phase-scans, are performed at LAMPF. The authors show that, based on simulation results, the primary causes of beam spill are inefficient longitudinal capture and the lack of longitudinal matching. Measurements to support these claims are not presently made at LAMPF. However, agreement between measurement and simulation for the transverse beam properties and transmissions serve to benchmark the simulations.

  9. Texas Intense Positron Source (TIPS)

    NASA Astrophysics Data System (ADS)

    O'Kelly, D.

    2003-03-01

    The Texas Intense Positron Source (TIPS) is a state of the art variable energy positron beam under construction at the Nuclear Engineering Teaching Laboratory (NETL). Projected intensities on the order of the order of 10^7 e+/second using ^64Cu as the positron source are expected. Owing to is short half-life (t1/2 12.8 hrs), plans are to produce the ^64Cu isotope on-site using beam port 1 of NETL TRIGA Mark II reactor. Following tungsten moderation, the positrons will be electrostatically focused and accelerated from few 10's of eV up to 30 keV. This intensity and energy range should allow routine performance of several analytical techniques of interest to surface scientists (PALS, PADB and perhaps PAES and LEPD.) The TIPS project is being developed in parallel phases. Phase I of the project entails construction of the vacuum system, source chamber, main beam line, electrostatic/magnetic focusing and transport system as well as moderator design. Initial construction, testing and characterization of moderator and beam transport elements are underway and will use a commercially available 10 mCi ^22Na radioisotope as a source of positrons. Phase II of the project is concerned primarily with the Cu source geometry and thermal properties as well as production and physical handling of the radioisotope. Additional instrument optimizing based upon experience gained during Phase I will be incorporated in the final design. Current progress of both phases will be presented along with motivations and future directions.

  10. The upgrade of the Brookhaven Linac Isotope Producer (BLIP) and the BNL Linac

    SciTech Connect

    Mausner, L.F.; Alessi, J.G.

    1996-12-31

    An upgrade project was recently completed on the 200 MeV H{sup -} linac and the Brookhaven Linac Isotope Producer (BLIP) in order to improve radioisotope production capacity and reliability. The average beam current has increased from 60 {mu}A to 150 {mu}A. The increased average current is the result of increases in peak current, from 25 mA to 37 mA, pulse repetition rate, from 5 to 7.5 Hz, and pulse width, from 500 to 530 ps. To achieve this performance the 35 keV, 750 keV and 200 MeV beam transport were improved, the RF transmission lines and RF power supplies replaced. Improvements to the linac control system, and the optics and vacuum system of the 200 MeV transport were implemented. A BLIP the target cooling system was upgraded to 35 kW and automated, the targets, and target mechanical systems replaced with a more robust design, and the control system upgraded. With these enhancements BLIP is ready to address the lack of availability of accelerator produced medical and research isotopes.

  11. High-Performance Beam Simulator for the LANSCE Linac

    SciTech Connect

    Pang, Xiaoying; Rybarcyk, Lawrence J.; Baily, Scott A.

    2012-05-14

    A high performance multiparticle tracking simulator is currently under development at Los Alamos. The heart of the simulator is based upon the beam dynamics simulation algorithms of the PARMILA code, but implemented in C++ on Graphics Processing Unit (GPU) hardware using NVIDIA's CUDA platform. Linac operating set points are provided to the simulator via the EPICS control system so that changes of the real time linac parameters are tracked and the simulation results updated automatically. This simulator will provide valuable insight into the beam dynamics along a linac in pseudo real-time, especially where direct measurements of the beam properties do not exist. Details regarding the approach, benefits and performance are presented.

  12. Using basic electromagnetism to introduce LINAC4 (CERN)

    NASA Astrophysics Data System (ADS)

    Cid-Vidal, Xabier; Cid, Ramon; Vretenar, Maurizio

    2016-07-01

    The LHC is the last element of CERN’s accelerator complex, which is a succession of machines with increasingly higher energies. Everything starts in the 50 MeV linear accelerator (LINAC2), but a new linear accelerator, the 160 MeV LINAC4, will replace LINAC2 in 2018, upgrading LHC injectors to higher intensity and eventually increasing the luminosity of LHC. The aim of this article is briefly introducing this new accelerator, and presenting a simple application of some fundamental laws of magnetism to be taken to the secondary school classrooms.

  13. R&D Energy Recovery Linac at Brookhaven National Laboratory

    SciTech Connect

    Litvinenko, Vladimir; Beavis, D.; Ben-Zvi, Ilan; Blaskiewicz, Michael; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Drees, K.A.; Ganetis, G.; Gamble, Michael; Hahn, H.; Hammons, L.R.; Hershcovitch, A.; Hseuh, H.C.; Jain, A.K.; Kayran, A.; Kewisch, Jorg; Lambiase, R.F.; Lederle, D.L.; Mahler, G.J.; McIntyre, G.; Meng, W.; Nehring, T.C.; Oerter, B.; Pai, C.; Pate, D.; Phillips, Daniel; Pozdeyev, Eduard; Rao, Triveni; Reich, J.; Roser, Thomas; Russo, T.; Smith, K.; Tuozzolo, Joseph; Weiss, D.; Williams, N.W.W.; Yip, Kin; Zaltsman, A.; Bluem, Hans; Cole, Michael; Favale, Anthony; Holmes, D.; Rathke, John; Schultheiss, Tom; Delayen, Jean; Funk, L.; Phillips, H.; Preble, Joseph

    2008-07-01

    Collider Accelerator Department at BNL is in the final stages of developing the 20-MeV R&D energy recovery linac with super-conducting 2.5 MeV RF gun and single-mode super-conducting 5-cell RF linac. This unique facility aims to address many outstanding questions relevant for high current (up to 0.5 A of average current), high brightness energy-recovery linacs with novel Zigzag-type merger. We present the performance of the R&D ERL elements and detailed commissioning plan.

  14. Positron microanalysis with high intensity beams

    SciTech Connect

    Hulett, L.D. Jr.; Donohue, D.L.

    1990-01-01

    One of the more common applications for a high intensity slow positron facility will be microanalysis of solid materials. In the first section of this paper some examples are given of procedures that can be developed. Since most of the attendees of this workshop are experts in positron spectroscopy, comprehensive descriptions will be omitted. With the exception of positron emission microscopy, most of the procedures will be based on those already in common use with broad beams. The utility of the methods have all been demonstrated, but material scientists use very few of them because positron microbeams are not generally available. A high intensity positron facility will make microbeams easier to obtain and partially alleviate this situation. All microanalysis techniques listed below will have a common requirement, which is the ability to locate the microscopic detail or area of interest and to focus the positron beam exclusively on it. The last section of this paper is a suggestion of how a high intensity positron facility might be designed so as to have this capability built in. The method will involve locating the specimen by scanning it with the microbeam of positrons and inducing a secondary electron image that will immediately reveal whether or not the positron beam is striking the proper portion of the specimen. This scanning positron microscope' will be a somewhat prosaic analog of the conventional SEM. It will, however, be an indispensable utility that will enhance the practicality of positron microanalysis techniques. 6 refs., 1 fig.

  15. Recirculating Linac Accelerators For Future Muon Facilities

    SciTech Connect

    Yves Roblin, Alex Bogacz, Vasiliy Morozov, Kevin Beard

    2012-04-01

    Neutrino Factories (NF) and Muon Colliders (MC) require rapid acceleration of shortlived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses superconducting RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness. We discuss the optics and technical requirements for RLA designs, using RF cavities capable of simultaneous acceleration of both m+ and m- species. The design will include the optics for the multi-pass linac and droplet-shaped return arcs.

  16. Permanent-magnet quadrupoles in RFQ Linacs

    SciTech Connect

    Lysenko, W.P.; Wang, T.F.

    1985-10-01

    We investigated the possibility of increasing the current-carrying capability of radio-frequency quadrupole (RFQ) linear accelerators by adding permanentmagnet quadrupole (PMQ) focusing to the existing transverse focusing provided by the rf electric field. Increased transverse focusing would also allow shortening RFQ linacs by permitting a larger accelerating gradient, which is normally accompanied by an undesirable increased transverse rf defocusing effect. We found that PMQs were not helpful in increasing the transverse focusing strength in an RFQ. This conclusion was reached after some particle tracing simulations and some analytical calculations. In our parameter regime, the addition of the magnets increases the betatron frequency but does not result in improved focusing because the increased flutter more than offsets the gain from the increased betatron frequency.

  17. Radiation processing with the Messina electron linac

    NASA Astrophysics Data System (ADS)

    Auditore, L.; Barnà, R. C.; De Pasquale, D.; Emanuele, U.; Loria, D.; Morgana, E.; Trifirò, A.; Trimarchi, M.

    2008-05-01

    In the last decades radiation processing has been more and more applied in several fields of industrial treatments and scientific research as a safe, reliable and economic technique. In order to improve existing industrial techniques and to develop new applications of this technology, at the Physics Department of Messina University a high power 5 MeV electron linac has been studied and set-up. The main features of the accelerating structure will be described together with the distinctive features of the delivered beam and several results obtained by electron beam irradiations, such as improvement of the characteristics of polymers and polymer composite materials, synthesis of new hydrogels for pharmaceutical and biomedical applications, reclaim of culture ground, sterilization of medical devices, development of new dosimeters for very high doses and dose rates required for monitoring of industrial irradiations.

  18. Energy Recovery Linacs for Light Source Applications

    SciTech Connect

    George Neil

    2011-04-01

    Energy Recovery Linacs are being considered for applications in present and future light sources. ERLs take advantage of the continuous operation of superconducting rf cavities to accelerate high average current beams with low losses. The electrons can be directed through bends, undulators, and wigglers for high brightness x ray production. They are then decelerated to low energy, recovering power so as to minimize the required rf drive and electrical draw. When this approach is coupled with advanced continuous wave injectors, very high power, ultra-short electron pulse trains of very high brightness can be achieved. This paper will review the status of worldwide programs and discuss the technology challenges to provide such beams for photon production.

  19. Neutron Spectra in a 15 MV LINAC

    SciTech Connect

    Vega-Carrillo, H. R.; Chu, Wei-Han; Tung, Chuan-Jong; Lan, Jen-Hong

    2010-12-07

    Neutron spectra were calculated inside the treatment hall of a 15 MV LINAC, calculations were carried out using Monte Carlo methods. With a Bonner sphere spectrometer with pairs of thermoluminiscent dosimeters the neutron spectrum at 100 cm from the isocenter was measured and compared with the calculated spectrum. All the spectra in the treatment hall show the presence of evaporation and knock-on neutrons; also the room-return due to the hall features is shown. In the maze the large contribution are due to epithermal and thermal neutrons. A good agreement between the calculated and measured spectrum at 100 cm was noticed, from this comparison the differences are attributed to the water content in the concrete of the hall.

  20. BEAM HALO IN PROTON LINAC BEAMS

    SciTech Connect

    T. WANGLER; K. CRANDALL

    2000-08-01

    In this paper we review the present picture of km halo in proton linacs. Space-charge forces acting in mismatched beams have been identified as a major cause of beam-halo. We present a definition of halo based on a ratio of moments of the distribution of the beam coordinates. We find from our initial studies that for halo detined in this way, a beam can have rms emittance growth without halo growth, but halo growth is always accompanied by rms emittance growth. We describe the beam-halo experiment that is in preparation at Los Alamos, which will address questions about the beam profiles, maximum particle amplitudes, and rms emittance growth associated with the halo.

  1. Design of the NLC positron source

    SciTech Connect

    Tang, H.; Emma, P.; Gross, G.; Kulikov, A.; Li, Z.; Miller, R.; Rinolfi, L.; Turner, J.; Yeremian, D.

    1996-08-01

    The design of the positron source for the Next Linear Collider (NLC) is presented. The key features of this design include accelerating positrons at an L-band frequency (1428 MHz) and using a rotating positron target with multi-stage differential pumping. Positron yield simulations show that the L-band design yields at the source 2.5 times the beam intensity required at the interaction point and is easily upgrade to higher intensities required for the 1 TeV NLC upgrade. Multi-bunch beam loading compensation schemes in the positron capture and booster accelerators and the optics design of the positron booster accelerator are described. For improved source efficiency, the design boasts two parallel positron vaults adequately shielded from each other such that one serves as an on-line spare.

  2. A Program for Optimizing SRF Linac Costs

    SciTech Connect

    Powers, Thomas J.

    2013-04-01

    Every well-designed machine goes through the process of cost optimization several times during its design, production and operation. The initial optimizations are done during the early proposal stage of the project when none of the systems have been engineered. When a superconducting radio frequency (SRF) linac is implemented as part of the design, it is often a difficult decision as to the frequency and gradient that will be used. Frequently, such choices are made based on existing designs, which invariably necessitate moderate to substantial modifications so that they can be used in the new accelerator. Thus the fallacy of using existing designs is that they will frequently provide a higher cost machine or a machine with sub-optimal beam physics parameters. This paper describes preliminary results of a new software tool that allows one to vary parameters and understand the effects on the optimized costs of construction plus 10 year operations of an SRF linac, the associated cryogenic facility, and controls, where operations includes the cost of the electrical utilities but not the labor or other costs. It derives from collaborative work done with staff from Accelerator Science and Technology Centre, Daresbury, UK [1] several years ago while they were in the process of developing a conceptual design for the New Light Source project. The initial goal was to convert a spread sheet format to a graphical interface to allow the ability to sweep different parameter sets. The tools also allow one to compare the cost of the different facets of the machine design and operations so as to better understand the tradeoffs.

  3. 1-GeV Linac Upgrade Study at Fermilab

    SciTech Connect

    Popovic, M., Moretti, A., Noble, R., Schmidt, C. W., FNAL

    1998-09-01

    A linac injector for a new proton source complex at Fermilab is assumed to have a kinetic energy of 1 GeV. This linac would be sized to accelerate 100 mA of H{sup -} beam in a 200 microsecond pulse at a 15 Hz repetition rate. This would be adequate to produce {approximately}10{sup 14} protons per pulse allowing for future improvements of the new proton source complex. An alternate proposal is to add 600 MeV of side coupled cavity linac at 805 MHz to the existing 400 MeV Linac. This addition may either be in a new location or use the present Booster tunnel. A discussion of these possibilities will be given.

  4. Design of the driver linac for the Rare Isotope Accelerator.

    SciTech Connect

    Ostroumov, P. N.; Nolen, J. A.; Shepard, K. W.; Physics

    2006-01-01

    The proposed design of the Rare Isotope Accelerator (RIA) driver linac is a cw, fully superconducting, 1.4 GV linac capable of accelerating uranium ions up to 400 MeV/u and protons to 1 GeV with 400 kW beam power. An extensive research and development effort has resolved many technical issues related to the construction of the driver linac and other systems of the RIA facility. In particular, record intensities of heavy ion beams have been demonstrated with the ECR ion source VENUS at LBNL, the driver front end systems including two-charge-state Low Energy Beam Transport (LEBT) and RFQ are being tested, and a set of SC accelerating structures to cover velocity range from 0.02c to 0.7c have been developed and prototyped. Newly developed high-performance SC cavities will provide the required voltage for the driver linac using 300 cavities designed for six different geometrical betas.

  5. A Radiation shielding study for the Fermilab Linac

    SciTech Connect

    Rakhno, I.; Johnstone, C.; /Fermilab

    2006-02-01

    Radiation shielding calculations are performed for the Fermilab Linac enclosure and gallery. The predicted dose rates around the access labyrinth at normal operation and a comparison to measured dose rates are presented. An accident scenario is considered as well.

  6. RF linac designs with beams in thermal equilibrium

    NASA Astrophysics Data System (ADS)

    Reiser, Martin; Brown, Nathan

    1996-06-01

    Beams in conventional radio-frequency linear accelerators (rf linacs) usually have a transverse temperature which is much larger than the longitudinal temperature. With high currents, space charge forces couple the transverse and longitudinal particle motions, driving the beam toward thermal equilibrium, which leads to emittance growth and halo formation. A design strategy is proposed in which the beam has equal transverse and longitudinal temperatures through the entire linac, avoiding these undesirable effects. For such equipartitioned linac beams, simple analytical relationships can be derived for the bunch size, tune depression, and other parameters as a function of beam intensity, emittance, and external focusing. These relations were used to develop three conceptual designs for a 938 MeV, 100 mA proton linac with different tune depressions, which are presented in this paper.

  7. Commissioning of the LCLS Linac and Bunch Compressors

    SciTech Connect

    Akre, R.; Brachmann, A.; Decker, F.-J.; Ding, Y.; Dowell, D.; Emma#, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, Ph.; Huang, Z.; Iverson, R.; Limborg-Deprey, C.; Loos, H.; Molloy, S.; Miahnahri, A.; Nuhn, H.-D.; Ratner, D.; Turner, J.; Welch, J.; White, W.; /SLAC

    2008-08-20

    The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) project under construction at SLAC [1]. The injector section, from drive-laser and RF photocathode gun through the first bunch compressor, was commissioned in the spring and summer of 2007. The second phase of commissioning, including the second bunch compressor and various main linac modifications, was completed in January through August of 2008. We report here on experience gained during this second phase of machine commissioning, including the injector, the first and second bunch compressor stages, the linac up to 14 GeV, and beam stability measurements. The final commissioning phase, including the undulator and the long transport line from the linac, is set to begin in December 2008, with first light expected in July 2009.

  8. High power operational experience with the LANSCE Linac

    SciTech Connect

    Rybarcyk, Lawrence J

    2008-01-01

    The heart of the Los Alamos Neutron Science Center (LANSCE) is a pulsed linear accelerator that is used to simultaneously provide H+ and H- beams to several user facilities. This accelerator contains two Cockcroft-Walton style injectors, a 100-MeV drift tube linac and an 800-MeV coupled cavity linac. This presentation will touch on various aspects of the high power operation including performance, tune-up strategy, beam losses and machine protection.

  9. Evolution of the 400 MeV linac design

    SciTech Connect

    MacLachlan, J.A.

    1987-11-09

    The basic premises of the conceptual design for the linac upgrade are pursued to establish lengths, gradients, power dissipation, etc., for the 400 MeV linac and matching section. The discussion is limited to accelerating and focusing components. Wherever values depend on the choice of the accelerating structure, the disk-and-washer structure is emphasized; the results are generally relevant to the side coupled cavity choice also.

  10. Effect of cooling water on stability of NLC linac components

    SciTech Connect

    F. Le Pimpec et al.

    2003-02-11

    Vertical vibration of linac components (accelerating structures, girders and quadrupoles) in the NLC has been studied experimentally and analytically. Effects such as structural resonances and vibration caused by cooling water both in accelerating structures and quadrupoles have been considered. Experimental data has been compared with analytical predictions and simulations using ANSYS. A design, incorporating the proper decoupling of structure vibrations from the linac quadrupoles, is being pursued.

  11. Beam dynamics aspects for the APT integrated linac

    SciTech Connect

    Nath, S.; Gray, E.R.; Wangler, T.P.

    1997-08-01

    The accelerator-based production of tritium calls for a high-power cw proton linac. The current Los Alamos design uses an integrated approach in terms of accelerating structure. The front part of the accelerator uses normal-conducting (NC) structures while most (>80%) of the linac structure is superconducting (SC). Here, the authors report the beam-dynamics rationale used in the integrated design and present particle simulation results.

  12. A design approach for superconducting high-current ion linacs

    SciTech Connect

    Garnett, R.W.; Wangler, T.P.

    1996-09-01

    An approach for designing superconducting high-current ion linacs is described. This approach takes advantage of the large velocity acceptance of high-gradient cavities with a small number of cells. It is well known that this feature leads to a linac design with great operational flexibility. Algorithms which have been incorporated into a design code and a beam dynamics code are discussed. Simulation results using these algorithms are also presented.

  13. Positron annihilation in transparent ceramics

    NASA Astrophysics Data System (ADS)

    Husband, P.; Bartošová, I.; Slugeň, V.; Selim, F. A.

    2016-01-01

    Transparent ceramics are emerging as excellent candidates for many photonic applications including laser, scintillation and illumination. However achieving perfect transparency is essential in these applications and requires high technology processing and complete understanding for the ceramic microstructure and its effect on the optical properties. Positron annihilation spectroscopy (PAS) is the perfect tool to study porosity and defects. It has been applied to investigate many ceramic structures; and transparent ceramics field may be greatly advanced by applying PAS. In this work positron lifetime (PLT) measurements were carried out in parallel with optical studies on yttrium aluminum garnet transparent ceramics in order to gain an understanding for their structure at the atomic level and its effect on the transparency and light scattering. The study confirmed that PAS can provide useful information on their microstructure and guide the technology of manufacturing and advancing transparent ceramics.

  14. Positron scattering from vinyl acetate

    NASA Astrophysics Data System (ADS)

    Chiari, L.; Zecca, A.; Blanco, F.; García, G.; Brunger, M. J.

    2014-09-01

    Using a Beer-Lambert attenuation approach, we report measured total cross sections (TCSs) for positron scattering from vinyl acetate (C4H6O2) in the incident positron energy range 0.15-50 eV. In addition, we also report an independent atom model with screening corrected additivity rule computation results for the TCSs, differential and integral elastic cross sections, the positronium formation cross section and inelastic integral cross sections. The energy range of these calculations is 1-1000 eV. While there is a reasonable qualitative correspondence between measurement and calculation for the TCSs, in terms of the energy dependence of those cross sections, the theory was found to be a factor of ˜2 larger in magnitude at the lower energies, even after the measured data were corrected for the forward angle scattering effect.

  15. The 400 MeV Linac Upgrade at Fermilab

    SciTech Connect

    Noble, R.J.

    1992-12-01

    The Fermilab Linac Upgrade in planned to increase the energy of the H{sup {minus}} linac from 200 to 400 MeV. This is intended to reduce the incoherent space-charge tuneshift at injection into the 8 GeV Booster which limit either the brightness or the total intensity of the beam. The Linac Upgrade will be achieved by replacing the last four 201.25 MHs drift-tube linac (DTL) tanks which accelerate the beam from 116 to 200 MeV, with seven 805 MRs side-coupled cavity modules operating at an average axial field of about 7.5 MV/meter. This will allow acceleration to 400 MeV in the existing Linac enclosure. Each accelerator module will be driven with a 12 MW klystron-based rf power supply. Three of seven accelerator modules have been fabricated, power tested and installed in their temporary location adjacent to the existing DTL. All seven RF Modulators have been completed and klystron installation has begun. Waveguide runs have completed from the power supply gallery to the accelerator modules. The new linac will be powered in the temporary position without beam in order to verify overall system reliability until the laboratory operating schedule permits final conversion to 400 MeV operation.

  16. A novel electron gun for inline MRI-linac configurations

    SciTech Connect

    Constantin, Dragoş E. Fahrig, Rebecca; Holloway, Lois; Keall, Paul J.

    2014-02-15

    Purpose: This work introduces a new electron gun geometry capable of robust functioning in the presence of a high strength external magnetic field for axisymmetric magnetic resonance imaging (MRI)-linac configurations. This allows an inline MRI-linac to operate without the need to isolate the linear accelerator (linac) using a magnetic shield. This MRI-linac integration approach not only leaves the magnet homogeneity unchanged but also provides the linac flexibility to move along the magnet axis of symmetry if the source to target distance needs to be adjusted. Methods: Simple electron gun geometry modifications of a Varian 600C electron gun are considered and solved in the presence of an external magnetic field in order to determine a set of design principles for the new geometry. Based on these results, a new gun geometry is proposed and optimized in the fringe field of a 0.5 T open bore MRI magnet (GE Signa SP). A computer model for the 6 MeV Varian 600C linac is used to determine the capture efficiency of the new electron gun-linac system in the presence of the fringe field of the same MRI scanner. The behavior of the new electron gun plus the linac system is also studied in the fringe fields of two other magnets, a 1.0 T prototype open bore magnet and a 1.5 T GE Conquest scanner. Results: Simple geometrical modifications of the original electron gun geometry do not provide feasible solutions. However, these tests show that a smaller transverse cathode diameter with a flat surface and a slightly larger anode diameter could alleviate the current loss due to beam interactions with the anode in the presence of magnetic fields. Based on these findings, an initial geometry resembling a parallel plate capacitor with a hole in the anode is proposed. The optimization procedure finds a cathode-anode distance of 5 mm, a focusing electrode angle of 5°, and an anode drift tube length of 17.1 mm. Also, the linac can be displaced with ±15 cm along the axis of the 0.5 T

  17. A novel electron gun for inline MRI-linac configurations

    PubMed Central

    Constantin, Dragoş E.; Holloway, Lois; Keall, Paul J.; Fahrig, Rebecca

    2014-01-01

    Purpose: This work introduces a new electron gun geometry capable of robust functioning in the presence of a high strength external magnetic field for axisymmetric magnetic resonance imaging (MRI)-linac configurations. This allows an inline MRI-linac to operate without the need to isolate the linear accelerator (linac) using a magnetic shield. This MRI-linac integration approach not only leaves the magnet homogeneity unchanged but also provides the linac flexibility to move along the magnet axis of symmetry if the source to target distance needs to be adjusted. Methods: Simple electron gun geometry modifications of a Varian 600C electron gun are considered and solved in the presence of an external magnetic field in order to determine a set of design principles for the new geometry. Based on these results, a new gun geometry is proposed and optimized in the fringe field of a 0.5 T open bore MRI magnet (GE Signa SP). A computer model for the 6 MeV Varian 600C linac is used to determine the capture efficiency of the new electron gun-linac system in the presence of the fringe field of the same MRI scanner. The behavior of the new electron gun plus the linac system is also studied in the fringe fields of two other magnets, a 1.0 T prototype open bore magnet and a 1.5 T GE Conquest scanner. Results: Simple geometrical modifications of the original electron gun geometry do not provide feasible solutions. However, these tests show that a smaller transverse cathode diameter with a flat surface and a slightly larger anode diameter could alleviate the current loss due to beam interactions with the anode in the presence of magnetic fields. Based on these findings, an initial geometry resembling a parallel plate capacitor with a hole in the anode is proposed. The optimization procedure finds a cathode-anode distance of 5 mm, a focusing electrode angle of 5°, and an anode drift tube length of 17.1 mm. Also, the linac can be displaced with ±15 cm along the axis of the 0.5 T

  18. Nonplanar positron-acoustic Gardner solitary waves in electron-positron-ion plasmas with superthermal electrons and positrons

    SciTech Connect

    Uddin, M. J. Alam, M. S.; Mamun, A. A.

    2015-02-15

    Nonplanar (cylindrical and spherical) positron-acoustic (PA) Gardner solitary waves (SWs) in an unmagnetized plasma system consisting of immobile positive ions, mobile cold positrons, and superthermal (kappa distributed) hot positrons and electrons are investigated. The modified Gardner equation is derived by using the reductive perturbation technique. The effects of cylindrical and spherical geometries, superthermal parameter of hot positrons and electrons, relative temperature ratios, and relative number density ratios on the PA Gardner SWs are studied by using the numerical simulations. The implications of our results in various space and laboratory plasma environments are briefly discussed.

  19. Positron annihilation in the interstellar medium

    NASA Technical Reports Server (NTRS)

    Guessoum, Nidhal; Ramaty, Reuven; Lingenfelter, Richard E.

    1991-01-01

    Positronium formation and annihilation are studied in a model for the interstellar medium consisting of cold cloud cores, warm partially ionized cloud envelopes, and hot intercloud gas. The gamma-ray spectra resulting from positron annihilation in these components of the interstellar medium are calculated. The spectra from the individual components are then combined, using two limiting assumptions for the propagation of the positrons, namely, that the positrons propagate freely throughout the interstellar medium, and that the positrons are excluded from the cold cloud cores. In the first case, the bulk of the positrons annihilate in the cloud cores and the annihilation line exhibits broad wings resulting from the annihilation of positronium formed by charge exchange in flight. In the second case, the positrons annihilate mainly in the warm envelopes, and the line wings are suppressed.

  20. Development of a transmission positron microscope

    NASA Astrophysics Data System (ADS)

    Matsuya, M.; Jinno, S.; Ootsuka, T.; Inoue, M.; Kurihara, T.; Doyama, M.; Inoue, M.; Fujinami, M.

    2011-07-01

    A practical transmission positron microscope (TPM) JEM-1011B has been developed to survey differences in the interaction of positron and electron beams with materials, and is installed in the Slow Positron Facility of High Energy Accelerator Research Organization (KEK). The TPM can share positron and electron beams, and can also be used as a transmission electron microscope (TEM). Positron transmission images up to magnification 10,000× (resolution: 50 nm) and positron diffraction patterns up to 044 family were successfully obtained by the TPM comparing them with those of electrons. The differences in material transmittances for both beams have been measured, and can be explained by the calculated results of the Monte Carlo simulation code PENELOPE-2008.

  1. Positron annihilation induced Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Weiss, Alex; Koymen, A. R.; Mehl, David; Jensen, K. O.; Lei, Chun; Lee, K. H.

    1990-01-01

    Recently, Weiss et al. have demonstrated that it is possible to excite Auger transitions by annihilating core electrons using a low energy (less than 30eV) beam of positrons. This mechanism makes possible a new electron spectroscopy, Positron annihilation induced Auger Electron Spectroscopy (PAES). The probability of exciting an Auger transition is proportional to the overlap of the positron wavefunction with atomic core levels. Since the Auger electron energy provides a signature of the atomic species making the transition, PAES makes it possible to determine the overlap of the positron wavefunction with a particular element. PAES may therefore provide a means of detecting positron-atom complexes. Measurements of PAES intensities from clean and adsorbate covered Cu surfaces are presented which indicate that approx. 5 percent of positrons injected into CU at 25eV produce core annihilations that result in Auger transitions.

  2. Study of space charge-dominated beam bunching and some aspects of SSF linac designs

    SciTech Connect

    1995-12-31

    This report is made up from works under the Agreement 1083P0015-35 between Los Alamos National Laboratory and Moscow Radiotechnical Institute. There are five report parts. In the 1-st, 2-nd, and 3-d parts works on SCD-beam dynamics understanding were continued. In the 4-th and 5-th parts two conceptual linac designs were considered: for deutron linac with energy of 40 MeV and for proton linac with energy 1 GeV. The both linacs have focusing by superconducting solenoids (SSF linacs). The 1 GeV proton CW linac design is an extension of the design from.

  3. Applications and advances of positron beam spectroscopy

    SciTech Connect

    Howell, R., LLNL

    1998-03-18

    Over 50 scientists from DOE-DP, DOE-ER, the national laboratories, academia and industry attended a workshop held on November 5-7, 1997 at Lawrence Livermore National Laboratory. Workshop participants were charged to address two questions: Is there a need for a national center for materials analysis using positron techniques and can the capabilities at Lawrence Livermore National Laboratory serve this need. To demonstrate the need for a national center, the workshop participants discussed the technical advantages enabled by high positron currents and advanced measurement techniques, the role that these techniques would play in materials analysis and the demand for the data. Livermore now leads the world in materials analysis capabilities by positrons due to developments in response to demands of stockpile stewardship. The Livermore facilities now include the world`s highest current beam of keV positrons, a scanning pulsed positron microprobe under development capable of three dimensional maps of defect size and concentration, an MeV positron beam for defect analysis of large samples, and electron momentum spectroscopy by positrons. It was concluded that the positron microprobe under development at LLNL and other new instruments that would be relocated at LLNL at the high current keV source are an exciting step forward in providing results for the positron technique. These new data will impact a wide variety of applications.

  4. An induction linac developed for FEL application

    NASA Astrophysics Data System (ADS)

    de Mascureau, J.; Anthouard, Ph.; Bardy, J.; Eyharts, Ph.; Eyl, P.; Launspach, J.; Thevenot, M.; Villate, D.

    1992-07-01

    An induction linac is being studied and built at CESTA for FEL application. At first we studied the induction technology and namely the high-voltage (HV) generators and the induction cells. A HV generator designed to feed the cells with calibrated pulses (150 kV, 50 ns, δV/V < 1%) has been built using a resonant charging system and magnetic switches. This generator is planned for kHz repetition-rate operation. A prototype induction cell has also been built and tested with a cable generator. An electron injector (1.5 MeV, 1.5kA) has been designed and is now under test: it uses ten induction cells and a thermionic dispenser cathode. Numerical codes have been developed and simulations have been compared with experimental results for HV generators, induction cells, and the injector. An induction accelerating module has been studied and we plan to have the accelerator working at 3 MeV in 1992.

  5. Electron gun system for NSC KIPT linac

    NASA Astrophysics Data System (ADS)

    Zhou, Zu-Sheng; He, Da-Yong; Chi, Yun-Long

    2014-06-01

    In the NSC KIPT linac, a neutron source based on a subcritical assembly driven by a 100 MeV/100 kW electron linear accelerator is under design and development. The linear accelerator needs a new high current electron gun. In this paper, the physical design, mechanical fabrication and beam test of this new electron gun are described. The emission current is designed to be higher than 2 A for the pulse width of 3 μs with repetition rate of 50 Hz. The gun will operate with a DC high voltage power supply that can provide a high voltage up to 150 kV. Computer simulations and optimizations have been carried out in the design stage, including the gun geometry and beam transport line. The test results of high voltage conditioning and beam test are presented. The operation status of the electron gun system is also included. The basic test results show that the design, manufacture, and operation of the new electron system are basically successful.

  6. Development of head docking device for linac-based radiosurgery with a Neptun 10 PC linac.

    PubMed

    Khoshbin Khoshnazar, Alireza; Bahreyni Toossi, Mohammad Taghi; Hashemian, Abdolreza; Salek, Roham

    Stereotactic radiosurgery is a method for focused irradiation of intracranial lesions. Linac-based radiosurgery is currently performed by two techniques: couch mounted and pedestal mounted. In the first technique a device is required to affix the patient's head to the couch and neoreover to translate it accurately. Structure of such a device constructed by the authors plus acceptance test performed for evaluation is described in the article. A head docking device has been designed and constructed according to geometry of linac's couch and also desired functions. The device is cornpletely made from aluminum and consists of four major components: attachment bar, lower structure with four moveing accuracy mechanical stability and isocentric accuracy were assessed in the frame of acceptance test. Translating accuracy, mechanical stability and isocentric accuracy were found to be respectively: 1 mm, 1.64 mm and 3.2 mm with accuracy of 95%. According to AAPM report no. 54, a head docking device should translate head with an accuracy of 1 mm; this recommendation has been met. Moreover, we have demonstrated that the isocentric accuracy and mechanical stability of the device are sufficient that the device on confidently be used in stereotactic treatment. PMID:17664152

  7. Positron emission tomography and autoradiography

    SciTech Connect

    Mazziotta, J.; Schelbert, H.R.

    1985-01-01

    This a text on cerebral and myocardial imaging using positron emission tomography and autoradiography. Authorities in nuclear medicine and biophysics define the central principles of these complex and rapidly evolving imagine technologies-their theoretical foundations, the nature of the biochemical events being measured, the basis for constructing tracer kinetic models, the criteria governing radiopharmaceutical design, and the rationale for PET in the clinical setting. After reviewing the characteristics of cerebral and myocardial hemodynamics, transport, and metabolism, the contributors detail the theory of PET and autoradiography, the instrumentation required, and the procedures involved.

  8. Positron scattering and annihilation in hydrogenlike ions

    NASA Astrophysics Data System (ADS)

    Green, D. G.; Gribakin, G. F.

    2013-09-01

    Diagrammatic many-body theory is used to calculate the scattering phase shifts, normalized annihilation rates Zeff, and annihilation γ spectra for positron collisions with the hydrogenlike ions He+, Li2+, B4+, and F8+. Short-range electron-positron correlations and longer-range positron-ion correlations are accounted for by evaluating nonlocal corrections to the annihilation vertex and the exact positron self-energy. The numerical calculation of the many-body theory diagrams is performed using B-spline basis sets. To elucidate the role of the positron-ion repulsion, the annihilation rate is also estimated analytically in the Coulomb-Born approximation. It is found that the energy dependence and magnitude of Zeff are governed by the Gamow factor that characterizes the suppression of the positron wave function near the ion. For all of the H-like ions, the correlation enhancement of the annihilation rate is found to be predominantly due to corrections to the annihilation vertex, while the corrections to the positron wave function play only a minor role. Results of the calculations for s-, p-, and d-wave incident positrons of energies up to the positronium-formation threshold are presented. Where comparison is possible, our values are in excellent agreement with the results obtained using other, e.g., variational, methods. The annihilation-vertex enhancement factors obtained in the present calculations are found to scale approximately as 1+(1.6+0.46ℓ)/Zi, where Zi is the net charge of the ion and ℓ is the positron orbital angular momentum. Our results for positron annihilation in H-like ions provide insights into the problem of positron annihilation with core electrons in atoms and condensed matter systems, which have similar binding energies.

  9. Low energy positron interactions with biological molecules

    NASA Astrophysics Data System (ADS)

    Wanniarachchi, Indika L.

    Calculations of the positron density distribution which can be used for positrons bound to midsize and larger molecules have been tested for smaller molecules and subsequently applied to investigate the most likely e +e-- annihilation sites for positrons interacting with biological molecules containing C, H, O, and N. In order to allow consideration of positrons bound to extended molecules with regions of different character and no particular symmetry, atom-centered positron basis sets of Gaussian-type functions were developed for positrons bound to molecules containing O, N, C, H, Li, Na, and Be. Testing shows that there is no need to scale the positron basis functions to take into account different effective charges on the atoms in different molecules. Even at the HF level of theory the calculated positron and the contact density of e+LiH system is in qualitative agreement with the most accurate calculation was done in ECG method. Also it has been found that for larger biological molecules such as derivation of formaldehyde can leave out positron basis sets centered on H atoms and still get qualitatively acceptable contact density distribution. According to our results, the electronic and positronic wavefunctions have the most overlap in the regions of most negative electrostatic potential in the parent molecule, and we can expect that a positron bound to the molecule will be more likely to annihilate with one of the electrons in these regions. Also we find that the highest energy occupied electronic orbital often does not make the largest contribution to e+e -- annihilation, and that the energy liberated by subsequent electronic relaxation is sufficient to break the backbone in several places in di-peptides and other organic molecules.

  10. Neutron dosimetry at a high-energy electron-positron collider

    NASA Astrophysics Data System (ADS)

    Bedogni, Roberto

    Electron-positron colliders with energy of hundreds of MeV per beam have been employed for studies in the domain of nuclear and sub-nuclear physics. The typical structure of such a collider includes an LINAC, able to produce both types of particles, an accumulator ring and a main ring, whose diameter ranges from several tens to hundred meters and allows circulating particle currents of several amperes per beam. As a consequence of the interaction of the primary particles with targets, shutters, structures and barriers, a complex radiation environment is produced. This paper addresses the neutron dosimetry issues associated with the operation of such accelerators, referring in particular to the DAΦ NE complex, operative since 1997 at INFN-Frascati National Laboratory (Italy). Special attention is given to the active and passive techniques used for the spectrometric and dosimetric characterization of the workplace neutron fields, for radiation protection dosimetry purposes.

  11. Radiation surveys of the Naval Postgraduate School LINAC. Master's thesis

    SciTech Connect

    Davidson, D.F.

    1992-06-01

    The NPS LINAC was initially designed for use in radiation damage and nuclear structure studies. The LINAC's role has subsequently evolved to include research in a variety of other areas such as the generation of coherent microwave, optical, and x-radiation. The use of high energy electrons produces a radiation environment for which personnel and equipment safety must be addressed. It is the purpose of this study to measure the radiation levels in the areas surrounding the LINAC and to identify the sources of that radiation. A guide is provided for the installation of additional supplemental shielding for the LINAC to further reduce radiation levels in areas occupied by personnel. Primary conclusions of this study are that the radiation levels produced by the linear accelerator are below statutory limits, and that a neutron energy correction factor different than currently used should be used for personnel dosimetry at the NPS LINAC. This will result in the reduction of the TLD measured neutron dose evaluation for personnel.

  12. Concepts and Applications of Energy Recovery Linacs (ERLs)

    SciTech Connect

    Gruner, Sol M.

    2004-05-12

    Energy Recovery Linacs are being explored as next generation synchrotron light sources. The fundamental x-ray beam properties from storage ring sources, such as the source size, brilliance, and pulse duration are limited by the dynamic equilibrium characteristic of the magnetic lattice that is the storage ring. Importantly, the characteristic equilibration time is long, involving thousands of orbits around the ring. Advances in laser-driven photoelectron sources allow the generation of electron bunches with superior properties for synchrotron radiation. ERLs preserve these properties by acceleration with a superconducting linac, followed by transport through a return loop hosting insertion devices, similar to that of a 3rd generation storage ring. The loop returns bunches to the linac 180 deg. out of accelerating phase for deceleration through the linac and disposal. Thus, the electron beam energy is recycled back into the linac RF field for acceleration of new bunches and the equilibrium degradation of bunches never occurs. The superior projected properties of ERLs beams include extraordinary brilliance and small source size, with concomitant high transverse coherence, x-ray pulse durations down to {approx}100 femtoseconds, and flexibility of operation. ERL projects are summarized. ERLs will be capable of hosting practically all experiments now being carried out at storage rings while also enabling new types of experiments.

  13. Mechanical Engineering of the Linac for the Spallation Neutron Source

    SciTech Connect

    Bultman, N.K.; Chen, Z.; Collier, M.; Erickson, J.L.; Guthrie, A.; Hunter, W.T.; Ilg, T.; Meyer, R.K.; Snodgrass, N.L.

    1999-03-29

    The linac for the Spallation Neutron Source (SNS) Project will accelerate an average current of 1 mA of H{sup {minus}} ions from 20 MeV to 1GeV for injection into an accumulator ring. The linac will be an intense source of H{sup {minus}} ions and as such requires advanced design techniques to meet project technical goals as well as to minimize costs. The DTL, CCDTL and CCL are 466m long and operate at 805 MHz with a maximum H{sup {minus}} input current of 28 mA and 7% rf duty factor. The Drift Tube Linac is a copper-plated steel structure using permanent magnetic quadrupoles. The Coupled-Cavity portions are brazed copper structures and use electromagnetic quads. RF losses in the copper are 80 MW, with total rf power supplied by 52 klystrons. Additionally, the linac is to be upgraded to the 2- and 4-MW beam power levels with no increase in duty factor. The authors give an overview of the linac mechanical engineering effort and discuss the special challenges and status of the effort.

  14. SC driver linac for a rare isotope facility.

    SciTech Connect

    Shepard, K. W.; Delayen, J. R.; Lyneis, C. M.; Nolen, J.; Ostroumov, P.; Staples, J. W.; Brawley, J.; Hovater, C.; Kedzie, M.; Kelly, M. P.; Mammosser, J.; Piller, C.; Portillo, M.

    1999-12-10

    An ion linac formed of superconducting rf cavities can provide a multi-beam driver accelerator for the production of nuclei far from stability. A multi-beam driver supports a wide variety of production reactions and methods. This paper outlines a concept for a 1.3 GV linac capable of delivering several hundred kilowatts of uranium beam at an energy of 400 MeV per nucleon. The linac would accelerate the full mass range of ions, and provide higher velocities for the lighter ions, for example 730 MeV for protons. The accelerator will consist of an ECR ion source injecting a normally conducting RFQ and four short IH structures, then feeding an array of more than 400 superconducting cavities of six different types, which range in frequency from 58 to 700 MHz. A novel feature of the linac is the acceleration of beams containing more than one charge state through portions of the linac, in order to maximize beam current for the heavier ions. Such operation is made feasible by the large transverse and longitudinal acceptance provided by the large aperture and high gradient which are characteristic of superconducting rf cavities.

  15. Fermilab 200 MeV linac control system hardware

    SciTech Connect

    Shea, M.F.

    1984-01-01

    This report is a description of the present Linac distributed control system that replaces the original Xerox computer and interface electronics with a network of 68000-based stations. In addition to replacing the obsolete Xerox equipment, goals set for the new system were to retain the fast response and interactive nature of the original system, to improve reliability, to ease maintenance, and to provide 15 Hz monitoring of all Linac parameters. Our previous experience with microcomputer installations showed that small, stand-alone control systems are rather straightforward to implement and have been proven to be reliable in operation, even in the severe environment of the 750-keV preaccelerator. The overall design of the Linac system incorporates the concept of many relatively small, stand-alone control systems networked together using an intercomputer communication network. Each station retains its local control system character but takes advantage of the network to allow an operator to interact with the entire Linac from any local console. At the same time, a link to the central computer system allows Host computers to also access parameters in the Linac.

  16. Short wavelength FELs using the SLAC linac

    NASA Astrophysics Data System (ADS)

    Winick, H.; Bane, K.; Boyce, R.; Cobb, J.; Loew, G.; Morton, P.; Nuhn, H.-D.; Paterson, J.; Pianetta, P.; Raubenheimer, T.; Seeman, J.; Tatchyn, R.; Vylet, V.; Pellegrini, C.; Rosenzweig, J.; Travish, G.; Prosnitz, D.; Scharlemann, E. T.; Halbach, K.; Kim, K.-J.; Schlueter, R.; Xie, M.; Bonifacio, R.; De Salvo, L.; Pierini, P.

    1994-08-01

    Recent technological developments have opened the possibility to construct a device which we call a linac coherent light source (LCLS) (C. Pellegrini et al., Nucl. Instr. and Meth. A 331 (1993) 223; H. Winick et al., Proc. IEEE 1993 Particle Accelerator Conf., Washington, DC, May 1993; C. Pellegrini, Nucl. Instr. and Meth. A 341 (1994) 326; J. Seeman, SPIE Meet. on Electron Beam Sources of High Brightness Radiation, San Diego, CA, July 1993 [1-4]); it would be a fourth-generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much shorter wavelength than the 240 nm that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3 to 100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high-energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low-gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by self-amplified-spontaneous-emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops (M. Cornacchia and H. Winick (eds.), SLAC Report 92/02; I. Ben-Zvi and H. Winick (eds.), BNL report 49651 [5,6]). The required low-emittance electron beam can be achieved with recently-developed rf photocathode electron guns (B.E. Carlsten, Nucl. Instr. and Meth. A 285 (1989) 313; J. Rosenzweig and L. Serafini, Proc. IEEE 1993 Particle Accelerator Conf., Washington, DC, 1993 [7,8]). The peak current is increased by about an

  17. Nondestructive examination using neutron activated positron annihilation

    DOEpatents

    Akers, Douglas W.; Denison, Arthur B.

    2001-01-01

    A method is provided for performing nondestructive examination of a metal specimen using neutron activated positron annihilation wherein the positron emitter source is formed within the metal specimen. The method permits in situ nondestructive examination and has the advantage of being capable of performing bulk analysis to determine embrittlement, fatigue and dislocation within a metal specimen.

  18. Ionisation of atomic hydrogen by positron impact

    NASA Technical Reports Server (NTRS)

    Spicher, Gottfried; Olsson, Bjorn; Raith, Wilhelm; Sinapius, Guenther; Sperber, Wolfgang

    1990-01-01

    With the crossed beam apparatus the relative impact-ionization cross section of atomic hydrogen by positron impact was measured. A layout of the scattering region is given. The first measurements on the ionization of atomic hydrogen by positron impact are also given.

  19. Positron collisions with alkali-metal atoms

    NASA Technical Reports Server (NTRS)

    Gien, T. T.

    1990-01-01

    The total cross sections for positron and electron collisions with potassium, sodium, lithium and rubidium are calculated, employing the modified Glauber approximation. The Modified Glauber cross sections for positron collision with potassium and sodium at low intermediate energies are found to agree reasonably well with existing experimental data.

  20. Gas Permeations Studied by Positron Annihilation

    NASA Astrophysics Data System (ADS)

    Yuan, Jen-Pwu; Cao, Huimin; Jean, X.; Yang, Y. C.

    1997-03-01

    The hole volumes and fractions of PC and PET polymers are measured by positron annihilation lifetime spectroscopy. Direct correlations between the measured hole properties and gas permeabilities are observed. Applications of positron annihilation spectroscopy to study gas transport and separation of polymeric materials will be discussed.

  1. Positron Emission Mammotomography with Dual Planar Detectors

    SciTech Connect

    Mark Smith; Raymond Raylman; Stanislaw Majewski

    2003-06-29

    Positron emission mammography (PEM) is usually performed with two stationary planar detectors above and below a compressed breast. There is image blurring normal to the detectors due to the limited angular range of the lines of response. Positron emission mammotomography (PEM-T) with dual planar detectors rotating about the breast can obtain complete angular sampling and has the potential to improve activity estimation.

  2. On the method of positron lifetime measurement

    NASA Technical Reports Server (NTRS)

    Nishiyama, F.; Shizuma, K.; Nasai, H.; Nishi, M.

    1983-01-01

    A fast-slow coincidence system was constructed for the measurement of positron lifetimes in material. The time resolution of this system was 270 ps for the (60)Co gamma rays. Positron lifetime spectra for 14 kinds of alkali halides were measured with this system. Two lifetime components and their intensities were derived from analyses of the lifetime spectra.

  3. Electron and Positron Stopping Powers of Materials

    National Institute of Standards and Technology Data Gateway

    SRD 7 NIST Electron and Positron Stopping Powers of Materials (PC database for purchase)   The EPSTAR database provides rapid calculations of stopping powers (collisional, radiative, and total), CSDA ranges, radiation yields and density effect corrections for incident electrons or positrons with kinetic energies from 1 keV to 10 GeV, and for any chemically defined target material.

  4. 21 CFR 892.1110 - Positron camera.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Positron camera. 892.1110 Section 892.1110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1110 Positron camera. (a) Identification. A...

  5. 21 CFR 892.1110 - Positron camera.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Positron camera. 892.1110 Section 892.1110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1110 Positron camera. (a) Identification. A...

  6. 21 CFR 892.1110 - Positron camera.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Positron camera. 892.1110 Section 892.1110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1110 Positron camera. (a) Identification. A...

  7. 21 CFR 892.1110 - Positron camera.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Positron camera. 892.1110 Section 892.1110 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1110 Positron camera. (a) Identification. A...

  8. Transient ions in electron and positron scattering

    NASA Astrophysics Data System (ADS)

    d'A Sanchez, Sergio; de Oliveira, Eliane M.; dos Santos, Josué S.; da Costa, Romarly F.; Bettega, Márcio H. F.; Lima, Marco A. P.; Varella, Márcio T. do N.

    2009-11-01

    We report on recent advances in studies of transient ions formed in electron and positron scattering by molecules. We briefly discuss elastic electron collisions against pyrrole and glycine, as well as electron affinities of glycine-water clusters. Positron scattering and annihilation on small molecules is also discussed.

  9. Applications of slow positrons to cancer research: Search for selectivity of positron annihilation to skin cancer

    NASA Astrophysics Data System (ADS)

    Jean, Y. C.; Li, Ying; Liu, Gaung; Chen, Hongmin; Zhang, Junjie; Gadzia, Joseph E.

    2006-02-01

    Slow positrons and positron annihilation spectroscopy (PAS) have been applied to medical research in searching for positron annihilation selectivity to cancer cells. We report the results of positron lifetime and Doppler broadening energy spectroscopies in human skin samples with and without cancer as a function of positron incident energy (up to 8 μm depth) and found that the positronium annihilates at a significantly lower rate and forms at a lower probability in the samples having either basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) than in the normal skin. The significant selectivity of positron annihilation to skin cancer may open a new research area of developing positron annihilation spectroscopy as a novel medical tool to detect cancer formation externally and non-invasively at the early stages.

  10. Gaseous Positronics - Positron interactions with atoms and molecules and their applications

    NASA Astrophysics Data System (ADS)

    Buckman, Stephen

    2011-05-01

    The advent of new technologies for accumulating, trapping and cooling positrons has led to a range of new experimental measurements of low energy positron interactions, and also prompted new, state-of-the-art theoretical advances in describing such interactions. This talk will present some of the recent experimental highlights of our program including the observation of threshold Wigner cusps, a search for quasi-bound positronic complexes or ``resonances,'' and measurements of positron interactions with biologically relevant molecules. The latter are an important precursor to the development of models of positron transport in soft matter and, ultimately, a positron dosimetry for techniques such as Positron Emission Tomography. Supported by the Australian Research Council's Centre of Excellence Program.

  11. Positron acoustic shock waves in four-component plasmas with nonthermal electrons and positrons

    NASA Astrophysics Data System (ADS)

    Rahman, M. M.; Mamun, A. A.; Alam, M. S.

    2014-06-01

    Positron acoustic shock waves (PASWs) in an unmagnetized four-component plasma system consisting of a cold mobile viscous positron fluid, hot positrons and electrons following the nonthermal distributions of Cairns et al. [Geophys. Res. Lett. 22, 2709 (1995)], and immobile positive ions are studied both analytically and numerically. The well-known reductive perturbation method is used to derive the Burgers equation. The basic features of the PASWs are significantly modified by the effects of the kinematic viscosity, the nonthermal electrons and hot positrons, the ratio of the electron temperature to the hot positron temperature σ, and the ratio of the hot positron (electron) number density to the cold positron number density μ 1 ( μ 2). The importance of our results to various astrophysical and laboratory plasmas are concisely discussed.

  12. Positronic complexes with unnatural parity

    SciTech Connect

    Bromley, M. W. J.; Mitroy, J.; Varga, K.

    2007-06-15

    The structure of the unnatural parity states of PsH, LiPs, NaPs, and KPs are investigated with the configuration interaction and stochastic variational methods. The binding energies (in hartree) are found to be 8.17x10{sup -4}, 4.42x10{sup -4}, 15.14x10{sup -4}, and 21.80x10{sup -4}, respectively. These states are constructed by first coupling the two electrons into a configuration which is predominantly {sup 3}P{sup e}, and then adding a p-wave positron. All the active particles are in states in which the relative angular momentum between any pair of particles is at least L=1. The LiPs state is Borromean since there are no three-body bound subsystems (of the correct symmetry) of the (Li{sup +}, e{sup -}, e{sup -}, e{sup +}) particles that make up the system. The dominant decay mode of these states will be radiative decay into a configuration that autoionizes or undergoes positron annihilation.

  13. DIAGNOSTIC TOOLS FOR BEAM HALO INVESTIGATION IN SNS LINAC

    SciTech Connect

    Aleksandrov, Alexander V; Blokland, Willem; Liu, Yun; Long, Cary D; Zhukov, Alexander P

    2012-01-01

    Uncontrolled beam loss is a major concern in the operation of a high intensity hadron linac. A low density cloud of particles with large oscillation amplitudes, so called halo, can form around the dense regular beam core. This halo can be a direct or indirect cause of beam loss. There is experimental evidence of halo growing in the SNS linac and limiting the further reduction of beam loss. A set of tools is being developed for detecting of the halo and investigating its origin and dynamics. The set includes high resolution emittance measurements in the injector, laser based emittance measurements at 1 GeV, and high resolution profile measurements along the linac. We will present our experience with useful measurement techniques and data analysis algorithms.

  14. R and D energy recovery LINAC at Brookhaven National Laboratory

    SciTech Connect

    Litvinenko,V.N.; Beavis, D.; Ben-Zvi, I.; Blaskiewicz, M.; Burrill, A.; Calaga, R.; Cameron, P.; Chang, X.; Drees, A.; Ganetis, G.; Gassner, D.; Hahn, H.; Hammons, L.; Hershcovitch, A.; Hseuh, H-C.; Jain, A.; Kayran, D.; Kewisch, J.; Lambiase, R.; Lederle, D.; Mahler, G.; McIntyre, G.; Meng, W.; Nehring, T.; Oerter, B.; Pai, C.; Pate, D.; Phillips, D.; Pozdeyev, E.; Rao, T.; Reich, J.; Roser, T.; Russo, T.; Smith, K.; Tuozzolo, J.; Weiss, D.; Williams, N.; Yip, K.; Zaltsman, A.; Favale, A.; Bluem, H.; Cole, M.; Holmes, D.; Rathke, J.; Schultheiss, T.; Todd, A.; Delayen, J.; Funk, L.; Phillips, L.; Preble, J.

    2008-06-23

    Collider Accelerator Department at BNL is in the final stages of developing the 20-MeV R and D energy recovery linac with super-conducting 2.5 MeV RF gun and single-mode super-conducting 5-cell RF linac. This unique facility aims to address many outstanding questions relevant for high current (up to 0.5 A of average current), high brightness energy-recovery linacs with novel ZigZag-type merger. Recent development in the R and D ERL plans include gun and 5-cell cavity (G5) test and possibility of using R and D ERL for proof-of-principle test of Coherent Electron Cooling at RHIC.

  15. The SLAC linac as used in the SLC collider

    SciTech Connect

    Seeman, J.T.; Abrams, G.; Adolphsen, C.; Atwood, W.; Bane, K.L.F.; Iverson, R.; Jacobsen, R.; Himel, T.M.; Jobe, R.K.; Lavine, T.L.

    1989-06-01

    The linac of the SLAC Linear Collider (SLC) must accelerate three high intensity bunches on each linac pulse from 1.2 GeV to 50 GeV with minimal increase of the small transverse emittance. The procedures and adjustments used to obtain this goal are outlined. Some of the accelerator parameters and components which interact are the beam energy, transverse position, component alignment, RF manipulation, feedback systems, quadrupole lattice, BNS damping, energy spectra, phase space matching, collimation, instrumentation and modelling. The method to bring these interdependent parameters collectively into specification has evolved over several years. This review is ordered in the sequence which is used to turn on the linac from a cold start and produce acceptable beams for the final focus and collisions. Approximate time estimates for the various activities are given. 21 refs.

  16. Overview and status of RF systems for the SSC Linac

    SciTech Connect

    Mynk, J.; Grippe, J.; Cutler, R.I.; Rodriguez, R.

    1993-05-01

    The Superconducting Super Collider (SSC) Linear Accelerator (Linac) produces a 600-MeV, 35-{mu}s, H-beam at a 10-Hz repetition rate. The beam is accelerated by a series of RF cavities. These consist of a Radio Frequency Quadrupole (RFQ), two bunchers, and four Drift Tube Linac (DTL) tanks at 427.617 MHz, and two bunchers, nine side-coupled Linac modules, and an energy compressor at 1282.851 MHz. The RFQ amplifier and the low-frequency buncher cavity amplifiers use gridded tubes, while the other cavities use klystron amplifier systems. The RF control system consists of a reference line and cavity feedback and feedforward loops for each amplifier. The RF amplifier system for each of these accelerator cavities is described, and the current status of each system is presented.

  17. Heavy-ion acceleration with a superconducting linac

    SciTech Connect

    Bollinger, L.M.

    1988-01-01

    This year, 1988, is the tenth anniversary of the first use of RF superconductivity to accelerate heavy ions. In June 1978, the first two superconducting resonators of the Argonne Tandem-Linac Accelerator System (ATLAS) were used to boost the energy of a /sup 19/F beam from the tandem, and by September 1978 a 5-resonator linac provided an /sup 16/O beam for a nuclear-physics experiment. Since then, the superconducting linac has grown steadily in size and capability until now there are 42 accelerating structures and 4 bunchers. Throughout this period, the system was used routinely for physics research, and by now the total time with beam on target is 35,000 hours. Lessons learned from this long running experience and some key technical developments that made it possible are reviewed in this paper. 19 refs., 3 figs., 2 tabs.

  18. Argonne tandem as injector to a superconducting linac

    SciTech Connect

    Yntema, J.L.; Den Hartog, P.K.; Henning, W.; Kutschera, W.

    1980-01-01

    The Argonne Tandem uses Pelletron chains, NEC accelerator tubes, and a dual closed-corona system. Its main function is to be an injector for a superconducting linear accelerator. As long as the transverse and longitudinal emittances are within the acceptance of the linac, the output beam quality of the tandem-linac system is essentially determined by the tandem. The sensitivity of the linac to the longitudinal emittance ..delta..E..delta..t of the incident beam makes the output beam quality dependent on the negative-ion velocity distribution in the source, transit-time effects in the tandem, molecular-beam dissociation, and stripper-foil uniformity. This paper discusses these beam-degrading effects.

  19. Investigations of Slow Motions of the SLAC Linac Tunnel

    SciTech Connect

    Seryi, Andrei

    2000-08-31

    Investigations of slow transverse motion of the linac tunnel of the Stanford Linear Collider have been performed over period of about one month in December 1999--January 2000. The linac laser alignment system, equipped with a quadrant photodetector, allowed submicron resolution measurement of the motion of the middle of the linac tunnel with respect to its ends. Measurements revealed two major sources responsible for the observed relative motion. Variation of the external atmospheric pressure was found to be the most significant cause of short wavelength transverse motion of the tunnel. The long wavelength component of the motion has been also observed to have a large contribution from tidal effects. The measured data are essential for determination of parameters for the Next Linear Collider.

  20. Thirty-five years of drift-tube linac experience

    SciTech Connect

    Knowles, H.B.

    1984-10-01

    The history of the drift-tube linear accelerator (linac) for the first 35 years of its existence is briefly reviewed. Both US and foreign experience is included. Particular attention is given to technological improvements, operational reliability, capital investment, and number of personnel committed to drift-tube linac (DTL) development. Preliminary data indicate that second- and third-generation (post-1960) DTLs have, in the US alone, operated for a combined total period of more than 75 machine-years and that very high reliability (>90%) has been achieved. Existing US drift-tube linacs represent a capital investment of at least $250 million (1983). Additional statistical evidence, derived from the proceedings of the last 11 linear accelerator conferences, supports the view that the DTL has achieved a mature technological base. The report concludes with a discussion of important recent advances in technology and their applications to the fourth generation of DTLs, many of which are now becoming operational.

  1. Optics and beam transport in energy recovery linacs

    NASA Astrophysics Data System (ADS)

    Hoffstaetter, Georg H.; Litvinenko, Vladimir; Owen, Hywel

    2006-02-01

    Here, we report on the working group "Optics and Beam Transport" of the 2005 Energy-Recovery-Linac Workshop. This workshop also had working groups on "Electron Guns and Injector Designs", "Superconducting RF and RF Control", and "Synchronization and Diagnostics/Instrumentation". Here, we are concerned with the many different ERL proposals that international laboratories have been working on. Subjects of concern are optics, accelerator design and modeling, stability requirements, designs of the merger that connects the conventional injector linac with the Energy Recovery Linac, longitudinal phase space manipulations to produce short pulses, beam dynamics and limitations by beam instabilities, and computational aspects of space-charge and synchrotron radiation effects. A coarse grain overview is given and reference is made to more detailed articles that were presented in this working group. Subjects are identified where collaborations should be encouraged and areas of future R&D are prioritized.

  2. Design considerations for high-current superconducting ion linacs

    SciTech Connect

    Delayen, J.R.; Bohn, C.L.; Micklich, B.J.; Roche, C.T.; Sagalovsky, L.

    1993-08-01

    Superconducting linacs may be a viable option for high-current applications such as fusion materials irradiation testing, spallation neutron source, transmutation of radioactive waste, tritium production, and energy production. These linacs must run reliably for many years and allow easy routine maintenance. Superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs, respectively. However, cost-effectiveness is not the sole consideration in these applications. For example, beam impingement must be essentially eliminated to prevent unsafe radioactivation of the accelerating structures, and thus large apertures are needed through which to pass the beam. Because of their high efficiency, superconducting cavities can be designed with very large bore apertures, thereby reducing the effect of beam impingement. Key aspects of high-current cw superconducting linac designs are explored in this context.

  3. Solenoid-based focusing in a proton linac

    SciTech Connect

    Terechkine, I; DiMarco, J.; Schappert, W.; Sergatskov, d.; Tartaglia, M.; /Fermilab

    2010-09-01

    Development of solenoid-based focusing lenses for the transport channel of an R&D linac front end at FNAL (HINS linac) is in its final stage. Superconducting lenses for the room temperature RF section of the linac are assembled into individual cryostats and certified using a dedicated test stand. During this certification process, the optical axis of each lens relative to the cryogenic vessel is found in the warm and cold state. Lenses for the superconducting RF sections are ready for production, and development of a cryomodule (which contains multiple superconducting lenses and RF cavities) is in progress. Studies have been conducted to measure fringe magnetic field of a lens in the cryomodule, to investigate a laser-based method of alignment, and to evaluate the extent of beam quality degradation due to imperfections in lens construction and alignment. This report presents some results of these studies.

  4. CONCEPTUAL DESIGN OF A LOW-BETA SC PROTON LINAC

    SciTech Connect

    R. W. GARNETT; T. P WANGLER; ET AL

    2001-04-01

    In this paper we discuss the conceptual design of a low-{beta} superconducting proton linac based on multi-gap spoke resonator structures. We have demonstrated the feasibility of using superconducting accelerating structures throughout a proton linac for high-peak current applications. The injection energy for this linac is assumed to be 6.7 MeV, which equals the output energy of the CW RFQ built for the Low-Energy Demonstration Accelerator now operating at Los Alamos. The beam is accelerated to 109 MeV using multi-gap spoke resonators. Both 2-gap and 3-gap cavities are used in three accelerating sections with geometric-{beta} values of 0.175, 0.2, and 0.34. Higher beam energies can be achieved by transitioning to elliptical superconducting cavities to further accelerate the beam. Preliminary beam-dynamics simulation results are shown and discussed.

  5. Real time bunch length measurements in the SLC linac

    SciTech Connect

    Sheppard, J.C.; Clendenin, J.E.; James, M.B.; Miller, R.H.; Ross, M.C.

    1985-02-01

    The longitudinal charge distribution of bunches accelerated in the Stanford Linear Collider (SLC) linac will strongly affect the performance of the Collider. Bunch lengths are chosen in a balance between the deleterious effects of longitudinal and transverse wakefields. The former impacts on the beam energy spread whereas the latter is important to the transverse emittance. Two bunch length measurement ports have been installed in the SLC linac: one in the injector region and one after the emittance damping ring to linac reinjection point. These ports utilize a fused quartz Cerenkov radiator in conjunction with an electrooptic streak camera to permit real time monitoring of single s-band buckets with a resolution of several picoseconds. The design of the radiators and light collection optics is discussed with an emphasis on those issues important to high resolution. Experimental results are presented. 7 refs., 4 figs.

  6. A hot-spare injector for the APS linac.

    SciTech Connect

    Lewellen, J. W.

    1999-04-13

    Last year a second-generation SSRL-type thermionic cathode rf gun was installed in the Advanced Photon Source (APS) linac. This gun (referred to as ''gun2'') has been successfully commissioned and now serves as the main injector for the APS linac, essentially replacing the Koontz-type DC gun. To help ensure injector availability, particularly with the advent of top-up mode operation at the APS, a second thermionic-cathode rf gun will be installed in the APS linac to act as a hot-spare beam source. The hot-spare installation includes several unique design features, including a deep-orbit Panofsky-style alpha magnet. Details of the hot-spare beamline design and projected performance are presented, along with some plans for future performance upgrades.

  7. An energy recovery electron linac-on-ring collider

    SciTech Connect

    Merminga, L.; Krafft, G.A.; Lebedev, V.A.; Ben-Zvi, I.

    2000-09-14

    We present the design of high-luminosity electron-proton/ion colliders in which the electrons are produced by an Energy Recovering Linac (ERL). Electron-proton/ion colliders with center of mass energies between 14 GeV and 100 GeV (protons) or 63 GeV/A (ions) and luminosities at the 10{sup 33}(per nucleon) level have been proposed recently as a means for studying hadronic structure. The linac-on-ring option presents significant advantages with respect to: (1) spin manipulations (2) reduction of the synchrotron radiation load in the detectors (3) a wide range of continuous energy variability. Rf power and beam dump considerations require that the electron linac recover the beam energy. Based on extrapolations from actual measurements and calculations, energy recovery is expected to be feasible at currents of a few hundred mA and multi-GeV energies. Luminosity projections for the linac-ring scenario based on fundamental limitations are presented. The feasibility of an energy recovery electron linac-on-proton ring collider is investigated and four conceptual point designs are shown corresponding to electron to proton energies of: 3 GeV on 15 GeV, 5 GeV on 50 GeV and 10 GeV on 250 GeV, and for gold ions with 100 GeV/A. The last two designs assume that the protons or ions are stored in the existing RHIC accelerator. Accelerator physics issues relevant to proton rings and energy recovery linacs are discussed and a list of required R and D for the realization of such a design is presented.

  8. Application of electron linacs in medicine, food sterilization and synchrotron light sources

    NASA Astrophysics Data System (ADS)

    Tran, Duc-Tien

    1989-04-01

    A review of the state of the art and new trends in electron linac technology is given with emphasis on three particular applications: radiotherapy, food sterilization and synchrotron light sources. The requirements on linac performances that these applications call for, namely energy variation flexibility, high power, high energy and low cost, will open linacs to new applications to come.

  9. BEAM SIMULATIONS USING VIRTUAL DIAGNOSTICS FOR THE DRIVER LINAC

    SciTech Connect

    R. C. York; X. Wu; Q. Zhao

    2011-12-21

    End-to-end beam simulations for the driver linac have shown that the design meets the necessary performance requirements including having adequate transverse and longitudinal acceptances. However, to achieve reliable operational performance, the development of appropriate beam diagnostic systems and control room procedures are crucial. With limited R&D funding, beam simulations provide a cost effective tool to evaluate candidate beam diagnostic systems and to provide a critical basis for developing early commissioning and later operational activities. We propose to perform beam dynamic studies and engineering analyses to define the requisite diagnostic systems of the driver linac and through simulation to develop and test commissioning and operational procedures.

  10. THE CONVENTIONAL FACILITIES REQUIREMENTS FOR THE SNS LINAC

    SciTech Connect

    P. TALLERICO; M. CROW; ET AL

    2001-06-01

    The Spallation Neutron Source (SNS) linac has a high gradient and 2 MW of beam power, and it therefore requires substantial RF power and cooling. There are 94 klystrons in its RF system, a large number for a proton linac. The optimization process and logic that lead to the klystron, transmitter, and power supply sizes is discussed. We also describe the requirements for building and tunnel area, electrical power, and water for this system. The trade-off decisions between low capital cost, low operating cost, and good maintainability are described.

  11. Commissioning plan for a high-current proton linac

    SciTech Connect

    Chan, K.C.D.; Barber, R.L.; Garnett, R.W.

    1997-09-01

    High-power proton linacs (E>500 MeV) are potentially useful for transmutation applications, such as the production of tritium. In production applications, high availability is essential. Achieving high availability requires an accelerator design that simplifies maintenance and accommodates commissioning procedures designed to minimize tune-up time. These are worthwhile goals for any accelerator, but the very high beam powers (170 MW) and heavy beam loading of the Accelerator Production of Tritium (APT) linac introduce significant new challenges. This paper will describe the commissioning plan, as developed to date.

  12. Neutron distribution and induced activity inside a Linac treatment room.

    PubMed

    Juste, B; Miró, R; Verdú, G; Díez, S; Campayo, J M

    2015-08-01

    Induced radioactivity and photoneutron contamination inside a radiation therapy bunker of a medical linear accelerator (Linac) is investigated in this work. The Linac studied is an Elekta Precise electron accelerator which maximum treatment photon energy is 15 MeV. This energy exceeds the photonuclear reaction threshold (around 7 MeV for high atomic number metals). The Monte Carlo code MCNP6 has been used for quantifying the neutron contamination inside the treatment room for different gantry rotation configuration. Walls activation processes have also been simulated. The approach described in this paper is useful to prevent the overexposure of patients and medical staff. PMID:26737878

  13. SRF cavities for CW option of Project X Linac

    SciTech Connect

    Solyak, N.; Gonin, I.; Khabiboulline, T.; Lunin, A.; Perunov, N.; Yakovlev, V.; /Fermilab

    2009-09-01

    Alternative option of Project X is based on the CW SC 2GeV Linac with the average current 1mA. Possible option of the CW Linac considered in the paper includes low energy part consisted of a few families SC Spoke cavities (from 2.5 MeV to 466 MeV) and high energy part consisted of 2 types of elliptical cavities (v/c=0.81 and v/c=1). Requirements and designed parameters of cavities are considered.

  14. LINAC BEAM DYNAMICS SIMULATIONS WITH PY-ORBIT

    SciTech Connect

    Shishlo, Andrei P

    2012-01-01

    Linac dynamics simulation capabilities of the PyORBIT code are discussed. PyORBIT is an open source code and a further development of the original ORBIT code that was created and used for design, studies, and commissioning of the SNS ring. The PyORBIT code, like the original one, has a two-layer structure. C++ is used to perform time-consuming computations, and the program flow is controlled from a Python language shell. The flexible structure makes it possible to use PyORBIT also for linac dynamics simulations. A benchmark of PyORBIT with Parmila and the XAL Online model is presented.

  15. Simplified RF power system for Wideroe-type linacs

    SciTech Connect

    Fugitt, J.; Howard, D.; Crosby, F.; Johnson, R.; Nolan, M.; Yuen, G.

    1981-03-01

    The RF system for the SuperHILAC injector linac was designed and constructed for minimum system complexity, wide dynamic range, and ease of maintenance. The final amplifier is close coupled to the linac and operates in an efficient semilinear mode, eliminating troublesome transmission lines, modulators, and high level regulators. The system has been operated at over 250 kW, 23 MHz with good regulation. The low level RF electronics are contained in a single chassis adjacent to the RF control computer, which monitors all important operating parameters. A unique 360/sup 0/ phase and amplitude modular is used for precise control and regulation of the accelerating voltage.

  16. Billion particle linac simulations for future light sources

    SciTech Connect

    Ryne, R. D.; Venturini, M.; Zholents, A. A.; Qiang, J.

    2008-09-25

    In this paper we report on multi-physics, multi-billion macroparticle simulation of beam transport in a free electron laser (FEL) linac for future light source applications. The simulation includes a self-consistent calculation of 3D space-charge effects, short-range geometry wakefields, longitudinal coherent synchrotron radiation (CSR) wakefields, and detailed modeling of RF acceleration and focusing. We discuss the need for and the challenges associated with such large-scale simulation. Applications to the study of the microbunching instability in an FEL linac are also presented.

  17. Positron deposition in plasmas by positronium beam ionization and transport of positrons in tokamak plasmas

    SciTech Connect

    Murphy, T.J.

    1986-11-01

    In a recently proposed positron transport experiment, positrons would be deposited in a fusion plasma by forming a positronium (Ps) beam and passing it through the plasma. Positrons would be deposited as the beam is ionized by plasma ions and electrons. Radial transport of the positrons to the limiter could then be measured by detecting the gamma radiation produced by annihilation of positrons with electrons in the limiter. This would allow measurements of the transport of electron-mass particles and might shed some light on the mechanisms of electron transport in fusion plasmas. In this paper, the deposition and transport of positrons in a tokamak are simulated and the annihilation signal determined for several transport models. Calculations of the expected signals are necessary for the optimal design of a positron transport experiment. There are several mechanisms for the loss of positrons besides transport to the limiter. Annihilation with plasma electrons and reformation of positronium in positron-hydrogen collisions are two such processes. These processes can alter the signal and place restrictions ons on the plasma conditions in which positron transport experiments can be effectively performed.

  18. Positron emission tomography: An overview

    PubMed Central

    Shukla, A. K.; Kumar, Utham

    2006-01-01

    The rate of glucose utilization in tumor cells is significantly enhanced as compared to normal cells and this biochemical characteristic is utilized in PET imaging using FDG as a major workhorse. The PET systems as well as cyclotrons producing positron emitting radiopharmaceuticals have undergone continuous technological refinements. While PET (CT) systems enable fusion images as well as precise attenuation correction, the self-shielded cyclotrons developed provide dedicated systems for in-house production of a large number of PET radiopharmaceuticals. The application of PET images in oncology includes those of pulmonary, colorectal, breast, lymphoma, head & neck, bone, ovarian and GI cancers. The PET has been recognized as promising diagnostic tool to predict biological and physiological changes at the molecular level and hence offer a potential area for future applications including Stem Cell research. PMID:21206635

  19. Positron emission tomography wrist detector

    DOEpatents

    Schlyer, David J.; O'Connor, Paul; Woody, Craig; Junnarkar, Sachin Shrirang; Radeka, Veljko; Vaska, Paul; Pratte, Jean-Francois

    2006-08-15

    A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal representing a time-of-occurrence of an annihilation event, generating an address signal representing a channel detecting the annihilation event, and generating a channel signal including the time and address signals. The method also includes generating a composite signal including the channel signal and another similarly generated channel signal concerning another annihilation event. An apparatus that serially transfers annihilation information includes a time signal generator, address signal generator, channel signal generator, and composite signal generator. The time signal is asynchronous and the address signal is synchronous to a clock signal. A PET scanner includes a scintillation array, detection array, front-end array, and a serial encoder. The serial encoders include the time signal generator, address signal generator, channel signal generator, and composite signal generator.

  20. Scintillators for positron emission tomography

    SciTech Connect

    Moses, W.W.; Derenzo, S.E.

    1995-09-01

    Like most applications that utilize scintillators for gamma detection, Positron Emission Tomography (PET) desires materials with high light output, short decay time, and excellent stopping power that are also inexpensive, mechanically rugged, and chemically inert. Realizing that this ``ultimate`` scintillator may not exist, this paper evaluates the relative importance of these qualities and describes their impact on the imaging performance of PET. The most important PET scintillator quality is the ability to absorb 511 keV photons in a small volume, which affects the spatial resolution of the camera. The dominant factor is a short attenuation length ({le} 1.5 cm is required), although a high photoelectric fraction is also important (> 30% is desired). The next most important quality is a short decay time, which affects both the dead time and the coincidence timing resolution. Detection rates for single 511 keV photons can be extremely high, so decay times {le} 500 ns are essential to avoid dead time losses. In addition, positron annihilations are identified by time coincidence so {le}5 ns fwhm coincidence pair timing resolution is required to identify events with narrow coincidence windows, reducing contamination due to accidental coincidences. Current trends in PET cameras are toward septaless, ``fully-3D`` cameras, which have significantly higher count rates than conventional 2-D cameras and so place higher demands on scintillator decay time. Light output affects energy resolution, and thus the ability of the camera to identify and reject events where the initial 511 keV photon has undergone Compton scatter in the patient. The scatter to true event fraction is much higher in fully-3D cameras than in 2-D cameras, so future PET cameras would benefit from scintillators with a 511 keV energy resolution < 10--12% fwhm.

  1. Prototyping of the ILC Baseline Positron Target

    SciTech Connect

    Gronberg, J; Brooksby, C; Piggott, T; Abbott, R; Javedani, J; Cook, E

    2012-02-29

    The ILC positron system uses novel helical undulators to create a powerful photon beam from the main electron beam. This beam is passed through a titanium target to convert it into electron-positron pairs. The target is constructed as a 1 m diameter wheel spinning at 2000 RPM to smear the 1 ms ILC pulse train over 10 cm. A pulsed flux concentrating magnet is used to increase the positron capture efficiency. It is cooled to liquid nitrogen temperatures to maximize the flatness of the magnetic field over the 1 ms ILC pulse train. We report on prototyping effort on this system.

  2. Slow-Positron Generator For Studying Polymer Films

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; St. Clair, Terry L.; Eftekhari, Abe

    1992-01-01

    Aspects of molecular structures probed by positron-annihilation spectroscopy (PAS). Slow-positron-beam generator suitable for PAS measurements in thin polymer films. Includes Na22 source of positrons and two moderators made of well-annealed tungsten foil. With proper choice of voltage, positrons emitted by inward-facing surfaces of moderators made to stop in polymer films tested.

  3. The Buffer-Gas Positron Accumulator and Resonances in Positron-Molecule Interactions

    NASA Technical Reports Server (NTRS)

    Surko, C.M.

    2007-01-01

    This is a personal account of the development of our buffer-gas positron trap and the new generation of cold beams that these traps enabled. Dick Drachman provided much appreciated advice to us from the time we started the project. The physics underlying trap operation is related to resonances (or apparent resonances) in positron-molecule interactions. Amusingly, experiments enabled by the trap allowed us to understand these processes. The positron-resonance "box score" to date is one resounding "yes," namely vibrational Feshbach resonances in positron annihilation on hydrocarbons; a "probably" for positron-impact electronic excitation of CO and NZ;an d a "maybe" for vibrational excitation of selected molecules. Two of these processes enabled the efficient operation of the trap, and one almost killed it in infancy. We conclude with a brief overview of further applications of the trapping technology discussed here, such as "massive" positron storage and beams with meV energy resolution.

  4. Beam Loss Studies for Rare Isotope Driver Linacs Final Report

    SciTech Connect

    Wangler, T P; Kurennoy, S S; Billen, J H; Crandall, K R; Qiang, J; Ryne, R D; Mustapha, B; Ostroumov, P; Zhao, Q; York, and R. C.

    2008-03-26

    The Fortran 90 RIAPMTQ/IMPACT code package is a pair of linked beam-dynamics simulation codes that have been developed for end-to-end computer simulations of multiple-charge-state heavy-ion linacs for future exotic-beam facilities. These codes have multiple charge-state capability, and include space-charge forces. The simulations can extend from the low-energy beam-transport line after an ECR ion source to the end of the linac. The work has been performed by a collaboration including LANL, LBNL, ANL, and MSU. The code RIAPMTQ simulates the linac front-end beam dynamics including the LEBT, RFQ, and MEBT. The code IMPACT simulates the beam dynamics of the main superconducting linac. The codes have been benchmarked for rms beam properties against previously existing codes at ANL and MSU. The codes allow high-statistics runs on parallel supercomputing platforms, particularly at NERSC at LBNL, for studies of beam losses. The codes also run on desktop PC computers for low-statistics work. The code package is described in more detail in a recent publication [1] in the Proceedings of PAC07 (2007 US Particle Accelerator Conference). In this report we describe the main activities for the FY07 beam-loss studies project using this code package.

  5. Status of the Project-X CW Linac Design

    SciTech Connect

    Ostiguy, J-F.; Solyak, N.; Berrutti, P.; Carneiro, J.P.; Lebedev, V.; Nagaitsev, S.; Saini, A.; Stheynas, B.; Yakovlev, V.P.; /Fermilab

    2012-05-01

    Project-X is a proposed proton accelerator complex at Fermilab that would provide particle beams to support a diversified experimental program at the intensity frontier. As currently envisioned, the complex would employ a CW superconducting linac to accelerate a 1 mA average, 5 mA peak H{sup -} beam from 2.1 MeV to 3 GeV. A second superconducting linac, operating in pulsed mode would ultimately accelerate a small fraction of this beam up to 8 GeV. The CW linac is based on five families of resonators operating at three frequencies: half-wave (1 family at 162.5 MHz), spoke (2 families at 325 MHz) and elliptical (2 families at 650 MHz). Accelerating and focusing elements are assembled in cryomodules separated by short warm sections. A long open region ({approx} 15 m) allows beam extraction at 1 GeV in support of a nuclear experimental program. In this paper, we present the latest iteration of the CW linac baseline lattice. We also briefly compare it to an alternative where the 162.5 half-wave resonators are replaced with 325 MHz spoke resonators.

  6. Intensity Effects of the FACET Beam in the SLAC Linac

    SciTech Connect

    Decker, F.-J.; Lipkowitz, N.; Sheppard, J.; White, G.R.; Wienands, U.; Woodley, M.; Yocky, G.; /SLAC

    2012-07-03

    The beam for FACET (Facility for Advanced aCcelerator Experimental Tests) at SLAC requires an energy-time correlation ('chirp') along the linac, so it can be compressed in two chicanes, one at the midpoint in sector 10 and one W-shaped chicane just before the FACET experimental area. The induced correlation has the opposite sign to the typical used for BNS damping, and therefore any orbit variations away from the center kick the tail of the beam more than the head, causing a shear in the beam and emittance growth. Any dispersion created along the linac has similar effects due to the high (>1.2% rms) energy spread necessary for compression. The initial huge emittances could be reduced by a factor of 10, but were still bigger than expected by a factor of 2-3. Normalized emittance of 3 {micro}m-rad in Sector 2 blew up to 150 {micro}m-rad in Sector 11 but could be reduced to about 6-12 {micro}m-rad, for the vertical plane although the results were not very stable. Investigating possible root causes for this, we found locations where up to 10 mm dispersion was created along the linac, which were finally verified with strong steering and up to 7 mm settling of the linac accelerator at these locations.

  7. A Cure for Multipass Beam Breakup in Recirculating Linacs

    SciTech Connect

    Byung C. Yunn

    2004-07-02

    We investigate a method to control the multipass dipole beam breakup instability in a recirculating linac including energy recovery. Effectiveness of an external feedback system for such a goal is shown clearly in a simplified model. We also verify the theoretical result with a simulation study.

  8. A METHOD TO CONTROL MULTIPASS BEAM BREAKUP IN RECIRCULATING LINACS

    SciTech Connect

    Byung Yunn

    2003-05-01

    We investigate a method to control the multipass dipole beam breakup instability in a recirculating linac including energy recovery. Effectiveness of an external feedback system for such a goal is shown clearly in a simplified model. We also verify the theoretical result with a simulation study.

  9. Optimization of steering elements in the RIA driver linac.

    SciTech Connect

    Lessner, E. S.; Aseev, V. S.; Ostroumov, P. N.; Physics

    2005-01-01

    The driver linac of the projected RIA facility is a versatile accelerator, a 1.4-GV, CW superconducting (SC) linac designed to simultaneously accelerate several heavy-ion charge states, providing beams from proton to uranium at 400 MeV/u at power levels at a minimum of 100 kW and up to 400 kW for most beams. Acceleration of multiple-charge-state uranium beams places stringent requirements on the linac design. A steering algorithm was derived that fulfilled the driver's real estate requirements, such as placement of steering dipole coils on SC solenoids and of beam position monitors outside cryostats, and beam-dynamics requirements, such as coupling effects induced by the focusing solenoids. The algorithm has been fully integrated into the tracking code TRACK and it is used to study and optimize the number and position of steering elements that minimize the multiple-beam centroid oscillations and preserve the beam emittance under misalignments of accelerating and transverse focusing elements in the driver linac.

  10. PERFORMANCE OF THE SNS FRONT END AND WARM LINAC

    SciTech Connect

    Aleksandrov, Alexander V; Allen, Christopher K; Cousineau, Sarah M; Danilov, Viatcheslav; Galambos, John D; Holmes, Jeffrey A; Jeon, Dong-O; Pelaia II, Tom; Plum, Michael A; Shishlo, Andrei P; Stockli, Martin P; Zhang, Yan

    2008-01-01

    The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H{sup -} injector, capable of producing one-ms-long pulses at 60 Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5 MeV beam from the Front End is accelerated to 87 MeV in the Drift Tube Linac, then to 186 MeV in a Coupled-Cavity Linac and finally to 1 GeV in the Superconducting Linac. With the completion of beam commissioning, the accelerator complex began operation in June 2006 and beam power is being gradually ramped up toward the design goal. Operational experience with the injector and linac will be presented including chopper performance, longitudinal beam dynamics study, and the results of a beam loss study.

  11. Heavy ion linac as a high current proton beam injector

    NASA Astrophysics Data System (ADS)

    Barth, Winfried; Adonin, Aleksey; Appel, Sabrina; Gerhard, Peter; Heilmann, Manuel; Heymach, Frank; Hollinger, Ralph; Vinzenz, Wolfgang; Vormann, Hartmut; Yaramyshev, Stepan

    2015-05-01

    A significant part of the experimental program at Facility for Antiproton and Ion Research (FAIR) is dedicated to pbar physics requiring a high number of cooled pbars per hour. The primary proton beam has to be provided by a 70 MeV proton linac followed by two synchrotrons. The new FAIR proton linac will deliver a pulsed proton beam of up to 35 mA of 36 μ s duration at a repetition rate of 4 Hz (maximum). The GSI heavy ion linac (UNILAC) is able to deliver world record uranium beam intensities for injection into the synchrotrons, but it is not suitable for FAIR relevant proton beam operation. In an advanced machine investigation program it could be shown that the UNILAC is able to provide for sufficient high intensities of CH3 beam, cracked (and stripped) in a supersonic nitrogen gas jet into protons and carbon ions. This advanced operational approach will result in up to 3 mA of proton intensity at a maximum beam energy of 20 MeV, 1 0 0 μ s pulse duration and a repetition rate of up to 2.7 Hz delivered to the synchrotron SIS18. Recent linac beam measurements will be presented, showing that the UNILAC is able to serve as a proton FAIR injector for the first time, while the performance is limited to 25% of the FAIR requirements.

  12. Critical design issues of high intensity proton linacs

    SciTech Connect

    Lawrence, G.P.

    1994-08-01

    Medium-energy proton linear accelerators are being studied as drivers for spallation applications requiring large amounts of beam powder. Important design factors for such high-intensity linacs are reviewed, and issues and concerns specific to this unprecedented power regime are discussed.

  13. MAFIA analysis of the effects of coupling slots in linacs

    NASA Astrophysics Data System (ADS)

    Adams, F. P.; Ungrin, J.; de Jong, M. S.

    1991-05-01

    We have used the MAFIA codes to analyze on-axis slot-coupled {π}/{2}- mode standing-wave linac structures. Quadrupolar fields in the structure are found to produce an elliptical accelerated beam. A modification to the design, yielding reduced beam ellipticity, is proposed.

  14. Time-dependent behavior of positrons in noble gases

    SciTech Connect

    Wadehra, J.M. . Dept. of Physics and Astronomy); Drallos, P.J. )

    1990-01-01

    Both equilibrium and nonequilibrium behaviors of positrons in several noble gases are reviewed. Our novel procedure for obtaining the time-dependent behavior of various swarm parameters -- such as the positron drift velocity, average positron energy, positron annihilation rate (or equivalently Z{sub eff}) etc. -- for positrons in pure ambient gases subjected to external electrostatic fields is described. Summaries of time-dependent as well as electric field-dependent results for positron swarms in various noble gases are presented. New time-dependent results for positron swarms in neon are also described in detail. 36 refs., 4 figs., 3 tabs.

  15. An Energy Recovery Electron Linac On Ring Collider

    SciTech Connect

    Nikolitsa Merminga; Geoffrey Krafft; Valeri Lebedev; Ilan Ben-Zvi

    2001-09-01

    Electron-proton/ion colliders with center of mass energies between 14 GeV and 100 GeV (protons) or 63 GeV/A (ions) and luminosities at the 10{sup 33} (per nucleon) level have been proposed recently as a means for studying hadronic structure. Electron beam polarization appears to be crucial for many of the experiments. Two accelerator design scenarios have been examined in detail: colliding rings and recirculating linac-on-ring. Although the linac-on-ring scenario is not as well developed as the ring-ring scenario, comparable luminosities appear feasible. The linac-on-ring option presents significant advantages with respect to: (1) spin manipulations; (2) reduction of the synchrotron radiation load in the detectors; (3) a wide range of continuous energy variability. Rf power and beam dump considerations require that the electron linac recover the beam energy. This technology has been demonstrated at Jefferson Lab's IR FEL with cw current up to 5 mA and beam energy up to 50 MeV. Based on extrapolations from actual measurements and calculations, energy recovery is expected to be feasible at higher currents (a few hundred mA) and higher energies (a few GeV) as well. The report begins with a brief overview of Jefferson Lab's experience with energy recovery and summarize its benefits. Luminosity projections for the linac-ring scenario based on fundamental limitations are presented next. The feasibility of an energy recovery electron linac-on-proton ring collider is investigated and four conceptual point designs are shown corresponding to electron to proton energies of: 3 GeV on 15 GeV, 5 GeV on 50 GeV and 10 GeV on 250 GeV, and for gold ions with 100 GeV/A. The last two designs assume that the protons or ions are stored in the existing RHIC accelerator. Accelerator physics issues relevant to proton rings and energy recovery linacs are discussed next and a list of required R and D for the realization of such a design is presented.

  16. Tentative design of beam focusing for the AHF linac and transport systems

    SciTech Connect

    Swain, G.R.

    1989-01-01

    Proposals for an advanced hadron facility include building afterburner linacs for LAMPF. A first afterburner, Add-on Linac number 1, is proposed to accelerate the beam from 0.8 to 1.6 GeV. The output beam would then be fed to a compressor ring and to another afterburner, Add-on Linac number 2. We make a rough estimate of the transverse focusing strength needed in these linacs, and consider the transport line from the end of the LAMPF 805-MHz linac to the start of Add-on Linac number 1. A rebuncher is needed in this transport line for proper acceptance of the beam into the add-on linac. 2 refs., 4 figs.

  17. Recent developments for high-intensity proton linacs

    SciTech Connect

    Wangler, T.P.; Garnett, R.W.; Gray, E.R.; Nath, S.

    1996-04-01

    High-intensity proton linacs are being proposed for new projects around the world, especially for tritium production, and for pulsed spallation neutron sources. Typical requirements for these linacs include peak beam current of about 100 mA, and final energies of 1 GeV and higher, APT, a tritium production linac, requires cw operation to obtain sufficient average tritium production linac, requires cw operation to obtain sufficient average beam power, and H{sup +} ion sources appear capable of providing the required current and emittances. The pulsed spallation neutron source requires a linac as an injector to one or more accumulator rings, and favors the use of an H{sup minus} beam to allow charge-exchange injection into the rings. For both applications high availability is demanded; the fraction of scheduled beam time for actual production must be 75% or more. Such a high availability requires low beam-loss to avoid radioactivation of the accelerator, and to allow hands-on maintenance that will keep the mean repair and maintenance times short. To keep the accelerator activation sufficiently low, the beam loss should not exceed about 0.1 to 1.0 nA/m, except perhaps for a few localized places, where special design adaptations could be made. The requirement of such small beam losses at such a high intensity presents a new beam physics challenge. This challenge will require greater understanding of the beam distribution, including the low- density beam halo, which is believed to be responsible for most of the beam losses. Furthermore, it will be necessary to choose the apertures so the beam losses will be acceptably low, and because large aperture size is generally accompanied by an economic penalty resulting from reduced power efficiency, an optimized choice of the aperture will be desirable.

  18. Positron kinetics in an idealized PET environment

    PubMed Central

    Robson, R. E.; Brunger, M. J.; Buckman, S. J.; Garcia, G.; Petrović, Z. Lj.; White, R. D.

    2015-01-01

    The kinetic theory of non-relativistic positrons in an idealized positron emission tomography PET environment is developed by solving the Boltzmann equation, allowing for coherent and incoherent elastic, inelastic, ionizing and annihilating collisions through positronium formation. An analytic expression is obtained for the positronium formation rate, as a function of distance from a spherical source, in terms of the solutions of the general kinetic eigenvalue problem. Numerical estimates of the positron range - a fundamental limitation on the accuracy of PET, are given for positrons in a model of liquid water, a surrogate for human tissue. Comparisons are made with the ‘gas-phase’ assumption used in current models in which coherent scattering is suppressed. Our results show that this assumption leads to an error of the order of a factor of approximately 2, emphasizing the need to accurately account for the structure of the medium in PET simulations. PMID:26246002

  19. Addiction Studies with Positron Emission Tomography

    SciTech Connect

    Joanna Fowler

    2008-10-13

    Brookhaven scientist Joanna Fowler describes Positron Emission Technology (PET) research at BNL which for the past 30 years has focused in the integration of basic research in radiotracer chemistry with the tools of neuroscience to develop new scientific

  20. Addiction Studies with Positron Emission Tomography

    ScienceCinema

    Joanna Fowler

    2010-01-08

    Brookhaven scientist Joanna Fowler describes Positron Emission Technology (PET) research at BNL which for the past 30 years has focused in the integration of basic research in radiotracer chemistry with the tools of neuroscience to develop new scientific

  1. Electron and positron induced processes. POSMOL 2013

    NASA Astrophysics Data System (ADS)

    Limão-Vieira, Paulo; Campeanu, Radu; Hoshino, Masamitsu; Ingólfsson, Oddur; Mason, Nigel; Nagashima, Yasuyuki; Tanuma, Hajime

    2014-09-01

    POSMOL 2013, the international meeting on electron and positron induced processes comprising the XVII International Workshop on Low-Energy Positron and Positronium Physics and the XVIII International Symposium on Electron-Molecule Collisions and Swarms, was held at Kanazawa Bunka Hall, Kanazawa, Ishikawa, Japan, from 19-21 July 2013. The XVII Workshop encompassed all aspects of positron, positronium and antiproton interactions with electrons, atoms, molecules and solid surfaces, and topics related to these, whereas the XVIII Symposium encompassed all aspects of electron interactions with molecules in both gaseous and condensed phases. Particular topics include studies of electron interactions with biomolecules, electron induced surface chemistry and the study of plasma processes. Recent research on the study of electron swarms was also highlighted. Contribution to the Topical Issue "Electron and Positron Induced Processes", edited by Michael Brunger, Radu Campeanu, Masamitsu Hoshino, Oddur Ingólfsson, Paulo Limão-Vieira, Nigel Mason, Yasuyuki Nagashima and Hajime Tanuma.

  2. Positron kinetics in an idealized PET environment.

    PubMed

    Robson, R E; Brunger, M J; Buckman, S J; Garcia, G; Petrović, Z Lj; White, R D

    2015-01-01

    The kinetic theory of non-relativistic positrons in an idealized positron emission tomography PET environment is developed by solving the Boltzmann equation, allowing for coherent and incoherent elastic, inelastic, ionizing and annihilating collisions through positronium formation. An analytic expression is obtained for the positronium formation rate, as a function of distance from a spherical source, in terms of the solutions of the general kinetic eigenvalue problem. Numerical estimates of the positron range - a fundamental limitation on the accuracy of PET, are given for positrons in a model of liquid water, a surrogate for human tissue. Comparisons are made with the 'gas-phase' assumption used in current models in which coherent scattering is suppressed. Our results show that this assumption leads to an error of the order of a factor of approximately 2, emphasizing the need to accurately account for the structure of the medium in PET simulations. PMID:26246002

  3. Positron kinetics in an idealized PET environment

    NASA Astrophysics Data System (ADS)

    Robson, R. E.; Brunger, M. J.; Buckman, S. J.; Garcia, G.; Petrović, Z. Lj.; White, R. D.

    2015-08-01

    The kinetic theory of non-relativistic positrons in an idealized positron emission tomography PET environment is developed by solving the Boltzmann equation, allowing for coherent and incoherent elastic, inelastic, ionizing and annihilating collisions through positronium formation. An analytic expression is obtained for the positronium formation rate, as a function of distance from a spherical source, in terms of the solutions of the general kinetic eigenvalue problem. Numerical estimates of the positron range - a fundamental limitation on the accuracy of PET, are given for positrons in a model of liquid water, a surrogate for human tissue. Comparisons are made with the ‘gas-phase’ assumption used in current models in which coherent scattering is suppressed. Our results show that this assumption leads to an error of the order of a factor of approximately 2, emphasizing the need to accurately account for the structure of the medium in PET simulations.

  4. Positron annihilation induced Auger electron emission

    SciTech Connect

    Weiss, A.; Jibaly, M.; Lei, Chun; Mehl, D.; Mayer, R.; Lynn, K.G.

    1988-01-01

    We report on measurements of Auger electron emission from Cu and Fe due to core hole excitations produced by the removal of core electrons by matter-antimatter annihilation. Estimates are developed of the probability of positrons annihilating with a 3p electron in these materials. Several important advantages of Positron annihilation induced Auger Electron Spectroscopy (PAES) for surface analysis are suggested. 10 refs., 2 figs.

  5. Feasibility and conceptual design of a C.W. positron source at CEBAF

    SciTech Connect

    Golge, Serkan

    2010-08-01

    A feasibility study of a CW positron source for the 12 GeV upgrade at Jefferson Lab (JLAB) is provided. The proposed ≥ 100 nA Continuous Wave (CW) positron source at JLAB has several unique and challenging characteristics: high current incident electron beam at 126 MeV with a high beam power (up to a MW); CW e- beam and CW e+ production. The multiple scattering is a dominant process when creating e+ in a target, which results a large phase space area of the emitted positrons. An admittance study was done at CEBAF to find the maximum phase space area, which is tolerated in the machine. The measured geometrical transverse admittance (A) were Ax =10 and Ay = 5 mm∙mrad at the injector. Energy spread measurement was also done at the ARC1. The fractional spread limit in the ARC1 was measured as δ = 3×10-3 at 653 MeV. By using the optimized results and the CEBAF parameters, three positron injector configurations are proposed; Combined Function Magnet, Two-Dipole and Microtron Dipole configurations. With the assumptions made, by using 126 MeV Ⓧ10 mA e- beam impinging on a 2 mm W target with a 100 μm spot size, we can get up to 3 μA useful e+ current at the North Linac connection. One of the biggest challenges is the target design, which the deposited power is about 60 kW. ILC designs project power deposition up to 13 kW, which would allow the creation of a e+ beam of up to 650 nA otherwise. The results of analytic and monte carlo simulations of the positron production, capture and acceleration are presented. For the target design, a review is presented of solutions for the high power production target. Portions of this dissertation work have been published in two conference proceedings.

  6. Positron annihilation studies of organic superconductivity

    SciTech Connect

    Yen, H.L.; Lou, Y.; Ali, E.H.

    1994-09-01

    The positron lifetimes of two organic superconductors, {kappa}-(ET){sub 2}Cu(NCS){sub 2} and {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br, are measured as a function of temperature across {Tc}. A drop of positron lifetime below {Tc} is observed. Positron-electron momentum densities are measured by using 2D-ACAR to search for the Fermi surface in {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br. Positron density distributions and positron-electron overlaps are calculated by using the orthogonalized linear combination atomic orbital (OLCAO) method to interprete the temperature dependence due to the local charge transfer which is inferred to relate to the superconducting transition. 2D-ACAR results in {kappa}-(ET){sub 2}Cu[N(CN){sub 2}]Br are compared with theoretical band calculations based on a first-principles local density approximation. Importance of performing accurate band calculations for the interpretation of positron annihilation data is emphasized.

  7. Intense low energy positron beams

    SciTech Connect

    Lynn, K.G.; Jacobsen, F.M.

    1993-12-31

    Intense positron beams are under development or being considered at several laboratories. Already today a few accelerator based high intensity, low brightness e{sup +} beams exist producing of the order of 10{sup 8} {minus} 10{sup 9} e{sup +}/sec. Several laboratories are aiming at high intensity, high brightness e{sup +} beams with intensities greater than 10{sup 9} e{sup +}/sec and current densities of the order of 10{sup 13} {minus} 10{sup 14} e{sup +} sec{sup {minus}} {sup 1}cm{sup {minus}2}. Intense e{sup +} beams can be realized in two ways (or in a combination thereof) either through a development of more efficient B{sup +} moderators or by increasing the available activity of B{sup +} particles. In this review we shall mainly concentrate on the latter approach. In atomic physics the main trust for these developments is to be able to measure differential and high energy cross-sections in e{sup +} collisions with atoms and molecules. Within solid state physics high intensity, high brightness e{sup +} beams are in demand in areas such as the re-emission e{sup +} microscope, two dimensional angular correlation of annihilation radiation, low energy e{sup +} diffraction and other fields. Intense e{sup +} beams are also important for the development of positronium beams, as well as exotic experiments such as Bose condensation and Ps liquid studies.

  8. High-power linac for a US spallation-neutron source

    SciTech Connect

    Wangler, T.P.; Billen, J.; Jason, A. Krawczyk, F.; Nath, S.; Shafer, R.; Staples, J.; Takeda, H.; Tallerico, P.

    1996-09-01

    We present status of high-power linac design studies for a proposed National Spallation Neutron Source (NSNS), based on a linac/accumulator-ring accelerator system. Overall project is a collaboration involving 5 national laboratories. ORNL will be responsible for the target, facilities, and conceptual design; BNL will be responsible for the ring; LBNL will be responsible for the injector, including the RFQ and a low-energy chopper in front of the RFQ; LANL will be responsible for the main linac; and ANL will be responsible for the instrumentation. The facility will be built at Oak Ridge. In the first phase, the dual-frequency linac with 402.5 and 805 MHz frequencies must deliver to the accumulator ring an H{sup -} beam near 1 GeV, with about 1 ms pulse length, a repetition rate 60 Hz, and average beam power {ge} 1 MW. The linac can be upgraded by a factor of 4 in beam power by increasing the dc injector current, and by funneling the beams from two 402.5 MHz low-energy linacs into the 805-MHz high-energy linac. Requirements for low beam loss in both linac and ring have important implications for linac design, including the requirement to provide efficient beam chopping to provide low-loss extraction for the ring. Linac design options and initial parameters are presented together with initial beam-dynamics simulation results.

  9. Primary cosmic ray positrons and galactic annihilation radiation

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1980-01-01

    The observation (Leventhal et al, 1978) of positron annihilation radiation at 0.511 MeV from the direction of the Galactic Center is reexamined, suggesting the possibility of a primary positron component of the cosmic rays. The observed 0.511 MeV emission requires a positron production rate nearly two orders of magnitude greater than the production rate of secondary cosmic ray positrons from pion decay produced in cosmic ray interactions. Possible sources of positrons are reviewed with both supernovae and pulsars appearing to be the more likely candidates. If only about 1% of these positrons were accelerated along with the cosmic ray nucleons and electrons to energies not less than 100 MeV, it is believed that these primary positrons would be comparable in intensity to those secondary positrons resulting from pion decay. Some observational evidence for the existence of primary positrons in the cosmic rays is also discussed.

  10. Positron production in heavy-ion collisions

    SciTech Connect

    Dunford, R.W.

    1995-08-01

    The ATLAS Positron Experiment APEX was built to study positron emission in collisions between very heavy ions. Narrow peaks were observed in such collisions at GSI, Darmstadt in the spectra of positrons and in the sum-energy spectra of electron-positron coincidences. APEX is a second-generation experiment which was specifically designed to look for the coincidence events and measure the opening angle between electrons and positrons. The first beam-induced positrons were detected using APEX in March 1993, and since then three additional runs were carried out. The first results for the collision system {sup 238}U + {sup 181}Ta show no evidence for sharp peaks in the electron-positron sum-energy spectrum. The current emphasis in this work is to obtain a complete understanding of the APEX apparatus. The atomic group is studying events involving coincidences between heavy ions and electrons. Since APEX measures the laboratory angles and energies of both electrons and heavy ions, it is possible to make an event-by-event Doppler correction of the electron spectra. These Doppler-corrected spectra show a number of lines which are attributed to conversion electrons which are emitted when a nuclear excited state decays by ejecting an inner-shell electron. The study of these spectra provide an important confirmation of the proper functioning of APEX. We are particularly concerned with the atomic physics aspects of this process. In order to understand the electron spectra, it is necessary to account for the change in binding energy of the inner-shell electrons as a function of ionic charge. We are utilizing the GRASP relativistic atomic structure program to calculate the binding energies. This information, together with the measured gamma-ray energies, allows us to calculate the expected energies of the conversion electrons which we can then compare with the observed Doppler-corrected conversion electron energies.

  11. Positron range estimations with PeneloPET

    NASA Astrophysics Data System (ADS)

    Cal-González, J.; Herraiz, J. L.; España, S.; Corzo, P. M. G.; Vaquero, J. J.; Desco, M.; Udias, J. M.

    2013-08-01

    Technical advances towards high resolution PET imaging try to overcome the inherent physical limitations to spatial resolution. Positrons travel in tissue until they annihilate into the two gamma photons detected. This range is the main detector-independent contribution to PET imaging blurring. To a large extent, it can be remedied during image reconstruction if accurate estimates of positron range are available. However, the existing estimates differ, and the comparison with the scarce experimental data available is not conclusive. In this work we present positron annihilation distributions obtained from Monte Carlo simulations with the PeneloPET simulation toolkit, for several common PET isotopes (18F, 11C, 13N, 15O, 68Ga and 82Rb) in different biological media (cortical bone, soft bone, skin, muscle striated, brain, water, adipose tissue and lung). We compare PeneloPET simulations against experimental data and other simulation results available in the literature. To this end the different positron range representations employed in the literature are related to each other by means of a new parameterization for positron range profiles. Our results are generally consistent with experiments and with most simulations previously reported with differences of less than 20% in the mean and maximum range values. From these results, we conclude that better experimental measurements are needed, especially to disentangle the effect of positronium formation in positron range. Finally, with the aid of PeneloPET, we confirm that scaling approaches can be used to obtain universal, material and isotope independent, positron range profiles, which would considerably simplify range correction.

  12. Van de Graaff based positron source production

    NASA Astrophysics Data System (ADS)

    Lund, Kasey Roy

    The anti-matter counterpart to the electron, the positron, can be used for a myriad of different scientific research projects to include materials research, energy storage, and deep space flight propulsion. Currently there is a demand for large numbers of positrons to aid in these mentioned research projects. There are different methods of producing and harvesting positrons but all require radioactive sources or large facilities. Positron beams produced by relatively small accelerators are attractive because they are easily shut down, and small accelerators are readily available. A 4MV Van de Graaff accelerator was used to induce the nuclear reaction 12C(d,n)13N in order to produce an intense beam of positrons. 13N is an isotope of nitrogen that decays with a 10 minute half life into 13C, a positron, and an electron neutrino. This radioactive gas is frozen onto a cryogenic freezer where it is then channeled to form an antimatter beam. The beam is then guided using axial magnetic fields into a superconducting magnet with a field strength up to 7 Tesla where it will be stored in a newly designed Micro-Penning-Malmberg trap. Several source geometries have been experimented on and found that a maximum antimatter beam with a positron flux of greater than 0.55x10 6 e+s-1 was achieved. This beam was produced using a solid rare gas moderator composed of krypton. Due to geometric restrictions on this set up, only 0.1-1.0% of the antimatter was being frozen to the desired locations. Simulations and preliminary experiments suggest that a new geometry, currently under testing, will produce a beam of 107 e+s-1 or more.

  13. Cylindrical and Spherical Positron-Acoustic Shock Waves in Nonthermal Electron-Positron-Ion Plasmas

    NASA Astrophysics Data System (ADS)

    Rahman, M. M.; Alam, M. S.; Mamun, A. A.

    2015-06-01

    The nonlinear propagation of cylindrical and spherical positron-acoustic shock waves (PASWs) in an unmagnetized four-component plasma (containing nonthermal distributed hot positrons and electrons, cold mobile viscous positron fluid, and immobile positive ions) is investigated theoretically. The modified Burgers equation is derived by employing the reductive perturbation method. Analytically, the effects of cylindrical and spherical geometries, nonthermality of electrons and hot positrons, relative number density and temperature ratios, and cold mobile positron kinematic viscosity on the basic features (viz. polarity, amplitude, width, phase speed, etc.) of PASWs are briefly addressed. It is examined that the PASWs in nonplanar (cylindrical and spherical) geometry significantly differ from those in planar geometry. The relevance of our results may be useful in understanding the basic characteristics of PASWs in astrophysical and laboratory plasmas.

  14. Accelerator control system at KEKB and the linac

    NASA Astrophysics Data System (ADS)

    Akiyama, Atsuyoshi; Furukawa, Kazuro; Kadokura, Eiichi; Kurashina, Miho; Mikawa, Katsuhiko; Nakamura, Tatsuro; Odagiri, Jun-ichi; Satoh, Masanori; Suwada, Tsuyoshi

    2013-03-01

    KEKB has completed all of the technical milestones and has offered important insights into the flavor structure of elementary particles, especially CP violation. The accelerator control system at KEKB and the injector linac was initiated by a combination of scripting languages at the operation layer and EPICS (experimental physics and industrial control system) at the equipment layer. During the project, many features were implemented to achieve extreme performance from the machine. In particular, the online linkage to the accelerator simulation played an essential role. In order to further improve the reliability and flexibility, two major concepts were additionally introduced later in the project, namely, channel access everywhere and dual-tier controls. Based on the improved control system, a virtual accelerator concept was realized, allowing the single injector linac to serve as three separate injectors to KEKB's high-energy ring, low-energy ring, and Photon Factory, respectively. These control technologies are indispensable for future particle accelerators.

  15. Focusing solenoids for the HINS Linac front end

    SciTech Connect

    Terechkine, I.; Appollinari, G.; Di-Marco, J.; Huang, Y.; Orris, D.; Page, T.; Rabehl, R.; Tartaglia, M.; Tompkins, J.; /Fermilab

    2008-10-01

    The low energy part of a linac for the High Intensity Neutrino Source (HINS) project at Fermilab will use superconducting solenoids as beam focusing elements (lenses). While the lenses for the conventional DTL-type accelerating section of the front end require individual cryostats, in the superconducting accelerating sections solenoids will be installed inside RF cryomodules. Some of the lenses in the conventional and in the superconducting sections are equipped with horizontal and vertical steering dipoles. Lenses for the DTL section are in the stage of production with certification activities ongoing at Fermilab. For the superconducting sections of the linac, a prototype lens has been built and tested. Each lens will be installed in the transport channel of the accelerator so that its magnetic axis is on the beamline. Corresponding technique has been developed at Fermilab and is used during the certification process. This report summarizes design features, parameters, and test results of the focusing lenses.

  16. Spatially periodic radio-frequency quadrupole focusing linac

    NASA Astrophysics Data System (ADS)

    Kolomiets, A. A.; Plastun, A. S.

    2015-12-01

    The new design for a spatially periodical rf quadrupole focusing linac is proposed. It consists of accelerating gaps formed between conventional cylindrical drift tubes, between drift tubes and rf quadrupoles with nonzero axial potential, and inside these rf quadrupoles, formed in the same way as in a conventional radio-frequency quadrupole (RFQ) linac with modulated electrodes. Such a combination provides both higher energy gain rate than conventional RFQ and stability of transverse motion for ion beams. The structure can be designed using various combinations of quadrupoles and drift tubes. Some options are considered in the paper using the smooth approximation method and computer simulation of beam dynamics. Transverse stability of particles has been studied. The proposed structure can provide suppression of rf defocusing effects on transverse beam dynamics. Some limitations of the spatially periodic rf quadrupole structure are mentioned.

  17. Maximizing Number of Passes in Recirculating Energy Recovery Linacs

    NASA Astrophysics Data System (ADS)

    Bogacz, S. Alex

    2016-03-01

    The next generation of high energy recirculating linear accelerators (RLAs) will rely on the energy recovery (ER) process for their extreme high current operation. Here, we discuss optimum design of multi-pass linac optics for an RLA based on a large scale superconducting linac. Initial strategy used in the design of 60 GeV, 6 pass RLA for the LHeC, has been extended to 10 passes for the proposed CEBAF ER experiment. The presented optimization scheme addresses overall beam transport performance, as well as specific beam dynamics issues, such as, beam stability due to collective effects. Work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.

  18. Multi-beam RFQ linac structure for heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Hayashizaki, Noriyosu; Ishibashi, Takuya; Ito, Taku; Hattori, Toshiyuki

    2009-07-01

    Both the RF linear accelerator (linac) and the linear induction accelerator have been considered as injectors in a driver system for heavy ion fusion (HIF). In order to relax beam defocusing by space charge effect in the low-energy region, the accelerating beams that were merged and had their beam currents increased by the funnel tree system are injected into storage rings. A multi-beam linac that accelerates multiple beams in an accelerator cavity has the advantages of cost reduction and downsizing of the system. We modeled the multi-beam Interdigital-H type radio frequency quadruple (IH-RFQ) cavities with the different beam numbers and evaluated the electromagnetic characteristics by simulation. As a result, the reasonable ranges of their configuration were indicated for a practical use.

  19. Multipass Arc Lattice Design for Recirculating Linac Muon Accelerators

    SciTech Connect

    G.M. Wang, R.P. Johnson, S.A. Bogacz, D. Trbojevic

    2009-05-01

    Recirculating linear accelerators (RLA) are the most likely means to achieve rapid acceleration of short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. A drawback of this scheme is that a separate return arc is required for each passage of the muons through the linac. In the work described here, a novel arc optics based on a Non-Scaling Fixed Field Alternating Gradient (NSFFAG) lattice is developed, which would provide sufficient momentum acceptance to allow multiple passes (two or more consecutive energies) to be transported in one string of magnets. An RLA with significantly fewer arcs will reduce the cost. We will develop the optics and technical requirements to allow the maximum number of passes by using an adjustable path length to accurately control the returned beam to synchronize with the linac RF phase.

  20. Beam-based alignment measurements of the LANSCE linac

    SciTech Connect

    McCrady, R. C.; Rybarcyk, L. J.

    2004-01-01

    We have made measurements of the alignment of the Los Alamos Neutron Science Center (LANSCE) Drift Tube linac (DTL) and Side Coupled linac (SCL) using beam position measurements and analyzing them with linear models. In the DTL, we varied the injection steering and focusing lattice strengths, measured the beam position after each DTL tank, and analyzed the data with a linear model using R-matrices that were either computed by the Trace-3D computer program or extracted from analysis of the data. The analysis model allowed for tank-to-tank misalignments. The measurements were made similarly in the SCL, where the analysis model allowed for misalignments of each quadrupole doublet lens. We present here the analysis techniques and the resulting beam-based alignment measurements.

  1. Cavities and Cryomodules for the RIA Driver Linac

    SciTech Connect

    Fuerst, J.D.; Shepard, K.W.; Kedzie, M.; Kelly, M.P.

    2004-06-23

    We describe cavities, cryomodules, and associated subsystem concepts for the Rare Isotope Accelerator (RIA) driver linac baseline design. Some alternative concepts are also presented. Beams from protons to uranium are accelerated with superconducting RF cavities operating from 57.5 MHz to 805 MHz. Substantial cost reduction over the baseline design may be achieved by replacing three classes of elliptical cell structures operating at 2 K by two classes of three-spoke drift tube structures. Cavity count and tunnel length are reduced while efficient cooling at 4.5 K for all linac structures may be possible. Issues include RF power requirements, microphonics, clean handling techniques, separate cavity and insulating vacuum systems, and heat load.

  2. Design of a Marx-Topology Modulator for FNAL Linac

    SciTech Connect

    Butler, T. A.; Garcia, F. G.; Kufer, M. R.; Pfeffer, H.; Wolff, D.

    2015-04-28

    The Fermilab Proton Improvement Plan (PIP) was formed in late 2011 to address important and necessary upgrades to the Proton Source machines (Injector line, Linac and Booster). The goal is to increase the proton flux by doubling the Booster beam cycle rate while maintaining the same intensity per cycle, the same uptime, and the same residual activation in the enclosure. For the Linac, the main focus within PIP is to address reliability. One of the main tasks is to replace the present hard-tube modulator used on the 200 MHz RF system. Plans to replace this high power system with a Marx-topology modulator, capable of providing the required waveform shaping to stabilize the accelerating gradient and compensate for beam loading, will be presented, along with development data from the prototype unit.

  3. H- AND PROTON BEAM LOSS COMPARISON AT SNS SUPERCONDUCTING LINAC

    SciTech Connect

    Aleksandrov, Alexander V; Galambos, John D; Plum, Michael A; Shishlo, Andrei P

    2012-01-01

    A comparison of beam loss in the superconducting part (SCL) of the Spallation Neutron Source (SNS) linac for H- and protons is presented. During the experiment the nominal beam of negative hydrogen ions in the SCL was replaced by a proton beam created by insertion of a thin stripping carbon foil placed in the low energy section of the linac. The observed significant reduction in the beam loss for protons is explained by a domination of the intra beam stripping mechanism of the beam loss for H-. The details of the experiment are discussed, and a preliminary estimation of the cross section of the reaction H- + H- -> H- + H0 + e is presented. Earlier, a short description of these studies was presented in [1].

  4. PROSPECTS FOR A VERY HIGH POWER CW SRF LINAC

    SciTech Connect

    Robert Rimmer

    2010-06-01

    Steady development in SRF accelerator technology combined with the success of large scale installations such as CEBAF at Jefferson Laboratory and the SNS Linac at ORNL gives credibility to the concept of very high average power CW machines for light sources or Proton drivers. Such machines would be powerful tools for discovery science in themselves but could also pave the way to reliable cost effective drivers for such applications as neutrino factories, an energy-frontier muon collider, nuclear waste transmutation or accelerator driven subcritical reactors for energy production. In contrast to machines such as ILC that need maximum accelerating gradient, the challenges in these machines are mainly in efficiency, reliability, beam stability, beam loss and of course cost. In this paper the present state of the art is briefly reviewed and options for a multi-GeV, multi-MW CW linac are discussed.

  5. MODEL BENCHMARK WITH EXPERIMENT AT THE SNS LINAC

    SciTech Connect

    Shishlo, Andrei P; Aleksandrov, Alexander V; Liu, Yun; Plum, Michael A

    2016-01-01

    The history of attempts to perform a transverse match-ing in the Spallation Neutron Source (SNS) superconduct-ing linac (SCL) is discussed. The SCL has 9 laser wire (LW) stations to perform non-destructive measurements of the transverse beam profiles. Any matching starts with the measurement of the initial Twiss parameters, which in the SNS case was done by using the first four LW stations at the beginning of the superconducting linac. For years the consistency between data from all LW stations could not be achieved. This problem was resolved only after significant improvements in accuracy of the phase scans of the SCL cavities, more precise analysis of all available scan data, better optics planning, and the initial longitudi-nal Twiss parameter measurements. The presented paper discusses in detail these developed procedures.

  6. Assessment of Alternative RF Linac Structures for APT

    SciTech Connect

    1997-03-26

    The APT program has been examining both normal and superconducting variants of the APT linac for the past two years. A decision on which of the two will be the selected technology will depend upon several considerations including the results of ongoing feasibility experiments, the performance and overall attractiveness of each of the design concepts, and an assessment of the system-level features of both alternatives. The primary objective of the Assessment of Alternative RF Linac Structures for APT study reported herein was to assess and compare, at the system-level, the performance, capital and life cycle costs, reliability/availability/maintainability (RAM) and manufacturing schedules of APT RF linear accelerators based upon both superconducting and normal conducting technologies. A secondary objective was to perform trade studies to explore opportunities for system optimization, technology substitution and alternative growth pathways and to identify sensitivities to design uncertainties.

  7. Linac4 low energy beam measurements with negative hydrogen ions

    SciTech Connect

    Scrivens, R. Bellodi, G.; Crettiez, O.; Dimov, V.; Gerard, D.; Granemann Souza, E.; Guida, R.; Hansen, J.; Lallement, J.-B.; Lettry, J.; Lombardi, A.; Midttun, Ø.; Pasquino, C.; Raich, U.; Riffaud, B.; Roncarolo, F.; Valerio-Lizarraga, C. A.; Wallner, J.; Yarmohammadi Satri, M.; Zickler, T.

    2014-02-15

    Linac4, a 160 MeV normal-conducting H{sup −} linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H{sup −} beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.

  8. Conversion of the AGS linac to H/sup -/ acceleration

    SciTech Connect

    Witkover, R.L.; Barton, D.S.; Reece, R.K.

    1983-01-01

    The AGS 200 MeV linac was converted to an H/sup -/ accelerator during the summer of 1982 using a magnetron-type source in the column of the second pre-injector pit. Because of the re-entrant electrode design, a 20 keV transport line was required to carry the beam to the first electrode. Several changes were made to the source which enhanced its performance over previous designs. The same H/sup -/ beam current is available at 2.75 times the duty factor with reduced deterioration of its output over several months of operation. The source, 750 keV transport, and linac modifications and performance will be presented.

  9. Elastic and inelastic scattering of positrons in gases and solids

    NASA Technical Reports Server (NTRS)

    Mcgowan, J. W.

    1972-01-01

    Three apparatuses were designed and built: The first, which is now operative, was designed to study the details of positron thermalization in solids and the subsequent emission of the low energy positrons from moderating foils; The second apparatus now under test is a positron bottle similar in design to an electron trap. It was built to store positrons at a fixed energy and to look at the number of stored positrons (storage time) as a function of a scattering gas in the vacuum chamber. The third apparatus is a crossed beam apparatus where positron-, alkali scattering will be studied. Much of the apparatus is now under test with electrons.

  10. HIGH DYNAMIC-RANGE HIGH SPEED LINAC CURRENT MEASUREMENTS

    SciTech Connect

    Deibele, Craig Edmond; Curry, Douglas E; Dickson, Richard W

    2012-01-01

    It is desired to measure the linac current of a charged particle beam with a consistent accuracy over a dynamic range of over 120 dB. Conventional current transformers suffer from droop, can be susceptible to electromagnetic interference (EMI), and can be bandwidth limited. A novel detector and electronics were designed to maximize dynamic range of about 120 dB and measure rise-times on the order of 10 nanoseconds.

  11. Longitudinal instability in heavy-ion-fusion induction linacs

    SciTech Connect

    Lee, E.P.

    1993-05-01

    A induction linac accelerating a high-current pulse of heavy ions at subrelativistic velocities is predicted to exhibit unstable growth of current fluctuations. An overview is given of the mode character, estimates of growth rates, and their application to an IFE driver. The present and projected effort to understand and ameliorate the instability is described. This includes particle-in-cell simulations, calculation and measurements of impedance, and design of feedback controls.

  12. A 10 MeV RF linac for industrial applications

    NASA Astrophysics Data System (ADS)

    Nayak, B.; Bhattacharjee, D.; Acharya, S.; Tillu, A. R.; Shivchandan; Chavan, R. B.; Choudhury, N.; Tiwari, R.

    2016-07-01

    This paper discusses the studies on a standing wave, biperiodic, on-axis coupled cavity RF linac operated at 2856 MHZ used for various industrial applications. Results of beam transmission experiments conducted in this accelerator have been presented. Analytical study and experimental verification of steady state beam loading in this facility have been explained. Finally some of the irradiation experiments performed in this system have been described.

  13. Literature Review on LINACs and FFAGs for Hadron Therapy

    NASA Astrophysics Data System (ADS)

    Verdú-Andrés, Silvia; Amaldi, Ugo; Faus-Golfe, Ángeles

    The document summarizes the recent papers, presentations and other public information on Radio-Frequency (RF) Linear Accelerators (linacs) and Fixed-Field Alternating-Gradient (FFAG) accelerators for hadron therapy. The main focus is on technical aspects of these accelerators. This report intends to provide a general overview of the state-of-the-art in those accelerators which could be used in short and middle-term for treating cancer.

  14. A self-adaptive feedforward rf control system for linacs

    NASA Astrophysics Data System (ADS)

    Zhang, Renshan; Ben-Zvi, Ilan; Xie, Jialin

    1993-01-01

    The design and performance of a self-adaptive feedforward rf control system are reported. The system was built for the linac of the Accelerator Test Facility (ATF) at Brookhaven National Laboratory. Variables of time along the linac macropulse, such as field or phase are discretized and represented as vectors. Upon turn-on or after a large change in the operating-point, the control system acquires the response of the system to test signal vectors and generates a linearized system response matrix. During operation an error vector is generated by comparing the linac variable vectors and a target vector. The error vector is multiplied by the inverse of the system's matrix to generate a correction vector is added to an operating point vector. This control system can be used to control a klystron to produce flat rf amplitude and phase pulses, to control a rf cavity to reduce the rf field fluctuation, and to compensate the energy spread among bunches in a rf linac. Beam loading effects can be corrected and a programmed ramp can be produced. The performance of the control system has been evaluated on the control of a klystron's output as well as an rf cavity. Both amplitude and phase have been regulated simultaneously. In initial tests, the rf output from a klystron has been regulated to an amplitude fluctuation of less than ±0.3% and phase variation of less than ±0.6°. The rf field of the ATF's photo-cathode microwave gun cavity has been regulated to ±0.5% in amplitude and simultaneously to ±1° in phase. Regulating just the rf field amplitude in the rf gun cavity, we have achieved amplitude fluctuation of less than ±0.2%.

  15. BEAM POSITION AND PHASE MONITORS FOR THE LANSCE LINAC

    SciTech Connect

    McCrady, Rodney C.; Gilpatrick, John D.; Power, John F.

    2011-01-01

    New beam-position and phase monitors are under development for the linac at the Los Alamos Neutron Science Center (LANSCE). Transducers have been designed and are being fabricated. We are considering many options for the electronic instrumentation to process the signals and provide position and phase data with the necessary precision and flexibility to serve the various required functions. We'll present the various options under consideration for instrumentation along with the advantages and shortcomings of these options.

  16. A Linac afterburner to supercharge the Fermilab booster

    SciTech Connect

    Charles M Ankenbrandt et al.

    2002-10-21

    A Linac Afterburner is proposed to raise the energy of the beam injected into the Femrilab Booster from 400 MeV to about 600 MeV, thereby alleviating the longitudinal and transverse space-charge effects at low energy that currently limit its performance. The primary motivation is to increase the integrated luminosity of the Tevatron Collider in Run II, but other future programs would also recap substantial benefits. The estimated cost is $23M.

  17. Simulation of waveguide FEL oscillator using RF linac

    SciTech Connect

    Kuruma, S.; Asakawa, M.; Imasaki, K.

    1995-12-31

    One dimensional multifrequency simulation code for waveguide mode FEL has been developed. Using this simulation code, we analyzed the spontaneous emission from electron micropulse from RF Linac. It is found that some parameters both high and low frequency waveguide modes are growing simultaneously, so the two radiation pulses are generated and amplified. And the experimental data for cavity length detuning of the radiation power are analyzed.

  18. BEAM POSITION AND PHASE MONITORS FOR THE LANSCE LINAC

    SciTech Connect

    McCrady, Rodney C.; Gilpatrick, John D.; Watkins, Heath A.

    2012-04-11

    New beam-position and phase monitors are under development for the linac at the Los Alamos Neutron Science Center (LANSCE.) Transducers have been designed and are being installed. We are considering many options for the electronic instrumentation to process the signals and provide position and phase data with the necessary precision and flexibility to serve the various required functions. We'll present the various options under consideration for instrumentation along with the advantages and shortcomings of these options.

  19. On radiation protection at the LINAC-800 linear electron accelerator

    NASA Astrophysics Data System (ADS)

    Balalykin, N. I.; Minashkin, V. F.; Nozdrin, M. A.; Shirkov, G. D.; Schegolev, V. Yu.

    2012-07-01

    The Automatic System of Radiation Safety Control (ASRSC) of the LINAC-800 linear electron accelerator is designed to ensure radiation safety for accelerator personnel during regular operations and in emergency cases. The results of calculating the emission power used to develop the ARPS are given. Both hardware and software components of the radiation control system are described. This paper also presents a description of the interlock and signalization system.

  20. Diagnostics for the 400 MeV FNAL Linac

    SciTech Connect

    McCrory, E.S.; Lee, G.

    1991-02-01

    The last four 201 MHz alvarez tanks of the twenty-year-old, 200 MeV Fermilab Linac are being replaced by seven high-gradient (7 KV/m), high-frequency (805 MHz) side-coupled-cavity structures to produce a 400 MeV beam for injection into the Booster. Good, reliable beam diagnostics are an important factor in the success of this project. This paper discusses the diagnostic systems.

  1. Development of a commissioning plan for the APT linac

    SciTech Connect

    Funk, L.W.; Crandall, K.R.; Gilpatrick, J.D.; Gray, E.R.; Regan, A.H.; Rohlev, A.; Rybarcyk, L.J.; Wangler, T.P.

    1998-12-31

    The Accelerator Production of Tritium (APT) facility is based on a linac which incorporates both normal-conducting and superconducting RF technology and accelerates a 100-mA cw proton beam to an energy of 1,030 MeV or higher, depending on the desired production rate. Commissioning plans to achieve full power operation with minimum beam-induced activation of components have been evolving. This paper presents the main issues and the basic approaches that are now being discussed.

  2. Electron capture from solids by positrons

    SciTech Connect

    Howell, R.

    1987-08-01

    The capture of electrons in solids is modified from that in gasses by several factors. The most important is the collective interaction of the electrons which results in a density of electron states in the solid in wide bands. Also the high density of electrons in many solids gives a high frequency of interaction as compared to gasses, and quickly destroys any electron-positron states in the metal matrix. Consequently, most positrons implanted in a metal will rapidly thermalize, and unless they reach the surface will annihilate with an electron in an uncorrelated state. Positronium formation from positrons scattered at a metal surface is analogous to ion neutralization however, most of the positronium comes from positrons passing through the surface from the bulk. The dominant motivation for studying positronium formation has been the hope that the distribution of the electrons at the surface would be obtained through the annihilation properties of positrons trapped at the surface or through analysis of the energy and angular distributions of the positronium emitted into the vacuum. These distributions have been measured and are included in this paper. 17 refs.

  3. A CF4 based positron trap

    NASA Astrophysics Data System (ADS)

    Marjanovic, Srdjan; Bankovic, Ana; Dujko, Sasa; Deller, Adam; Cooper, Ben; Cassidy, David; Petrovic, Zoran

    2016-05-01

    All positron buffer gas traps in use rely on N2 as the primary trapping gas due to its conveniently placed a1 Π electronic excitation cross section that is large enough to compete with positronium (Ps) formation in the threshold region. Its energy loss of 8.5 eV is sufficient to capture positrons into a potential well upon a single collision. The competing Ps formation, however, limits the efficiency of the two stage trap to 25 %. As positron moderators produce beams with energies of several eV we have proposed to use CF4 in the first stage of the trap, due to its large vibrational excitation cross section, where several vibrational excitations would be sufficient to trap the positrons with small losses. Apart from the simulations we also report the results of attempts to apply this approach to an existing Surko-type positron trap. Operating the unmodified trap as a CF4 based device proved to be unsuccessful, due primarily to excessive scattering due to high CF4 pressure in the first stage. However, the performance was consistent with subsequent simulations using the real system parameters. This agreement indicates that an efficient CF4 based scheme may be realized in an appropriately designed trap. also at Serbian Academy of Sciences and Arts, Knez Mihajlova 35, 11000 Belgrade, Serbia.

  4. A search for solar flare positrons

    NASA Technical Reports Server (NTRS)

    Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

    1975-01-01

    The detection of solar gamma-ray line emission and observations of the isotopes H2, H-3, and He-3 in solar cosmic rays provide direct evidence for the occurrence of high energy nuclear reactions in solar flare events. Appreciable numbers of other reaction products, including positrons with energies near about 1 MeV, should also be produced in such events. We have searched for positrons in the 0.16-1.6 MeV energy interval during 5 H-3 rich solar particle events. Based on calculations of positron and He-3 production at the sun, and using a simplified model of interplanetary propagation, we might expect comparable fluences of positrons and He-3 to be observed. Summing over these 5 events, we find the 0.16 to 1.6 MeV positron fluence to be a maximum of about 10% of the He-3 fluence with more tnan 1 MeV/nuc. This suggests that other processes, such as preferential trapping by the solar magnetic field, may be important.

  5. Transverse beam dynamics studies of a heavy ion induction linac

    SciTech Connect

    Garvey, T.; Eylon, S.; Fessenden, T.J.; Hahn, K.; Henestroza, E.; Keefe, D.

    1990-08-01

    The multiple beam induction linac experiment (MBE-4) was built to study the accelerator physics of the low energy, electrostatically focussed end of a driver for heavy ion inertial confinement fusion. In this machine four beams of Cs{sup +} ions are accelerated through 24 common induction gaps while being focussed in separate AG focussing channels. Each channel consists of a syncopated FODO lattice of 30 periods. We report results of the most recent studies of the transverse beam dynamics of a single drifting (180 keV) beam in this machine. The dependence of the emittance on the zero-current phase advance shows systematic variations which may be understood in the light of previous theoretical work on this topic. This result, unique to the beam parameters of a linac for heavy ion fusion, will be discussed in the context of its implications for a driver design. In addition we will discuss recent measurements of the motion of the beam centroid through the linac. These measurements, coupled with simulations, have proven to be a powerful tool in determining the presence of misalignment errors in the lattice of the accelerator. 6 refs., 3 figs.

  6. Electron Beam Focusing in the Linear Accelerator (linac)

    NASA Astrophysics Data System (ADS)

    Jauregui, Luis

    2015-10-01

    To produce consistent data with an electron accelerator, it is critical to have a well-focused beam. To keep the beam focused, quadrupoles (quads) are employed. Quads are magnets, which focus the beam in one direction (x or y) and defocus in the other. When two or more quads are used in series, a net focusing effect is achieved in both vertical and horizontal directions. At start up there is a 5% calibration error in the linac at Thomas Jefferson National Accelerator Facility. This means that the momentum of particles passing through the quads isn't always what is expected, which affects the focusing of the beam. The objective is to find exactly how sensitive the focusing in the linac is to this 5% error. A linac was simulated, which contained 290 RF Cavities with random electric fields (to simulate the 5% calibration error), and a total momentum kick of 1090 MeV. National Science Foundation, Department of Energy, Jefferson Lab, Old Dominion University.

  7. Accelerator mass spectrometry with a coupled tandem-linac system

    SciTech Connect

    Kutschera, W.

    1984-01-01

    A coupled system provides higher energies, which allows one to extend AMS to hitherto untouched mass regions. Another important argument is that the complexity, although bothersome for the operation, increases the selectivity of detecting a particular isotope. The higher-energy argument holds for any heavy-ion accelerator which is capable of delivering higher energy than a tandem. The present use of tandem-linac combinations for AMS, rather than cyclotrons, linacs or combinations of these machines, has mainly to do with the fact that this technique was almost exclusively developed around tandem accelerators. Therefore the tandem-linac combination is a natural extension to higher energies. The use of negative ions has some particular advantages in suppressing background from unwanted elements that do not form stable negative ions (e.g., N, Mg, Ar). On the other hand, this limits the detection of isotopes to elements which do form negative ions. For particular problems it may therefore be advantageous to use a positive-ion machine. What really matters most for choosing one or the other machine is to what extent the entire accelerator system can be operated in a truly quantiative way from the ion source to the detection system. 20 references, 4 figures.

  8. Reliability and availability studies in the RIA driver linac.

    SciTech Connect

    Lessner, E. S.; Ostroumov, P. N.; Physics

    2005-01-01

    The Rare Isotope Accelerator (RIA) facility will include various complex systems and must provide radioactive beams to many users simultaneously. The availability of radioactive beams for most experiments at the fully-commissioned facility should be as high as possible within design cost limitations. To make a realistic estimate of the achievable reliability a detailed analysis is required. The RIA driver linac is a complex machine containing a large number of superconducting (SC) resonators and capable of accelerating multiple-charge-state beams [1]. At the pre-CDR stage of the design it is essential to identify critical facility subsystem failures that can prevent the driver linac from operating. The reliability and availability of the driver linac were studied using expert information and data from operating machines such as ATLAS, APS, JLab, and LANL. Availability studies are performed with a Monte-Carlo simulation code previously applied to availability assessments of the NLC facility [2] and the results used to identify subsystem failures that most affect the availability and reliability of the RIA driver, and guide design iterations and component specifications to address identified problems.

  9. Relocatable cargo x-ray inspection systems utilizing compact linacs

    NASA Astrophysics Data System (ADS)

    Sapp, W. Wade; Mishin, Andrey V.; Adams, William L.; Callerame, Joseph; Grodzins, Lee; Rothschild, Peter J.; Schueller, Richard; Smith, Gerald J.

    2001-07-01

    Magnetron-powered, X-band linacs with 3-4 MeV capability are compact enough to be readily utilized in relocatable high energy cargo inspection systems. Just such a system is currently under development at AS&E™ using the commercially available ISOSearch™ cargo inspection system as the base platform. The architecture permits the retention of backscatter imaging, which has proven to be an extremely valuable complement to the more usual transmission images. The linac and its associated segmented detector will provide an additional view with superior penetration and spatial resolution. The complete system, which is housed in two standard 40' ISO containers, is briefly described with emphasis on the installation and operating characteristics of the portable linac. The average rf power delivered by the magnetron to the accelerator section can be varied up to the maximum of about 1 kW. The projected system performance, including radiation dose to the environment, will be discussed and compared with other high energy systems.

  10. Commissioning the FELI linac and UV-FEL facility

    SciTech Connect

    Tomimasu, T.; Saeki, K.; Miyauchi, Y.

    1995-12-31

    The FELI 165-MeV linac and UV-FEL facility are in the commissioning, stage. A thermionic triode gun of the 6-MeV injector emits 500-ps pulses of 2.3A at 22.3125MHz. These pulses are compressed to 60AX 7ps by a 714-MHz prebuncher and a 2856-MHz buncher and seven ETL type accelerating waveguides with a length of 2.93m. The length of the linac including bending sections of two S-type BT systems for two undulators used for IR-FEL oscillations is 46m. The buncher and these accelerating waveguides are powered by two klystrons (E3729, 2856MHz, total 48MW, 24-{mu}s flat top long pulses). The flatness of our klystron modulator pulses is 0.067% at 24-{mu}s duration. An rf-ageing for new four accelerating waveguides will be started in May. An S-type BT line for 165-MeV beam from the linac will be installed in the end of April. A 2.68-m undulator ({lambda}u=4.0cm, N=67, Kmax gap length {ge}16mm) and an optical cavity (Lc=6.72m) will be installed early in July. The beam conditionings for UV-FEL experiments will be started in July.

  11. Recent improvements to software used for optimization of SRF linacs

    SciTech Connect

    Powers, Tom J.

    2014-12-01

    This work describes a software tool that allows one to vary parameters and understand the effects on the optimized costs of construction plus 10 year operations of an SRF linac, where operation costs includes the cost of the electrical utilities but not the labor or other costs. The program includes estimates for the associated cryogenic facility, and controls hardware. The software interface provides the ability to vary the cost of the different aspects of the machine as well as to change the cryomodule and cavity types. Additionally, this work will describe the recent improvements to the software that allow one to estimate the costs of energy-recovery based linacs and to enter arbitrary values of the low field Q0 and Q0 slope. The initial goal when developing the software was to convert a spreadsheet format to a graphical interface and to allow the ability to sweep different parameter sets. The tools also allow one to compare the cost of the different facets of the machine design and operations so as to better understand tradeoffs. An example of how it was used to independently investigate cost optimization tradeoffs for the LCLS-II linac will also be presented.

  12. Multiple-linac approach for tritium production and other applications

    SciTech Connect

    Ruggiero, A.G.

    1995-01-10

    This report describes an approach to tritium production based on the use of multiple proton linear accelerators. Features of a single APTT Linac as proposed by the Los Alamos National Laboratory are presented and discussed. An alternative approach to the attainment of the same total proton beam power of 200 MW with several lower-performance superconducting Linacs is proposed and discussed. Although each of these accelerators are considerable extrapolations of present technology, the latter can nevertheless be built at less technical risk when compared to the single high-current APT Linac, particularly concerning the design and the performance of the low-energy front-end. The use of superconducting cavities is also proposed as a way of optimizing the accelerating gradient, the overall length, and the operational costs. The superconducting technology has already been successfully demonstrated in a number of large-size projects and should be seriously considered for the acceleration of intense low-energy beams of protons. Finally, each linear accelerator would represent an ideal source of very intense beams of protons for a variety of applications, such as: weapons and waste actinide transmutation processes, isotopes for medical application, spallation neutron sources, and the generation of intense beams of neutrinos and muons for nuclear and high-energy physics research. The research community at large has obviously an interest in providing expertise for, and in having access to, the demonstration, the construction, the operation, and the exploitation of these top-performance accelerators.

  13. Positron astrophysics and areas of relation to low-energy positron physics

    NASA Astrophysics Data System (ADS)

    Guessoum, Nidhal

    2014-05-01

    I briefly review our general knowledge of positron astrophysics, focusing mostly on the theoretical and modelling aspects. The experimental/observational aspects of the topic have recently been reviewed elsewhere [E. Churazov et al., Mon. Nat. R. Astron. Soc. 411, 1727 (2011); N. Prantazos et al., Rev. Mod. Phys. 83, 1001 (2011)]. In particular, I highlight the interactions and cross sections of the reactions that the positrons undergo in various cosmic media. Indeed, these must be of high interest to both the positron astrophysics community and the low-energy positron physics community in trying to find common areas of potential collaboration for the future or areas of research that will help the astrophysics community make further progress on the problem. The processes undergone by positrons from the moments of their birth to their annihilation (in the interstellar medium or other locations) are thus examined. The physics of the positron interactions with gases and solids (dust grains) and the physical conditions and characteristics of the environments where the processes of energy loss, positronium formation, and annihilation take place, are briefly reviewed. An explanation is given about how all the relevant physical information is taken into account in order to calculate annihilation rates and spectra of the 511 keV emission in the ISM; special attention is paid to positron interactions with dust and with polycyclic aromatic hydrocarbons. In particular, an attempt is made to show to what extent the interactions between positrons and interstellar dust grains are similar to laboratory experiments in which beams of low-energy positrons impinge upon solids and surfaces. Sample results are shown for the effect of dust grains on positron annihilation spectra in some phases of the ISM which, together with high resolution spectra measured by satellites, can be used to infer useful knowledge about the environment where the annihilation is predominantly taking place

  14. Studies of multipass beam breakup and energy recovery using the CEBAF injector linac

    SciTech Connect

    Sereno, N.S.; Cardman, L.S.; Krafft, G.A.; Sinclair, C.K.; Bisognano, J.J.

    1993-06-01

    Beam breakup (BBU) instabilities in superconducting linacs are a significant issue due to the potentially high Q values of the cavity higher order modes (HOMs). The CEBAF accelerator, which employs high CW current and 5-pass recirculation through two superconducting linacs, poses unique instability problems. An experimental investigation of multipass BBU along with energy recovery has been completed using a single recirculation through the CEBAF injector linac. Experimental results are compared with computer simulation of multipass BBU.

  15. Numerical simulations of stripping effects in high-intensity hydrogen ion linacs

    SciTech Connect

    Carneiro, J.-P.; Mustapha, B.; Ostroumov, P.N.; /Argonne

    2008-12-01

    Numerical simulations of H{sup -} stripping losses from blackbody radiation, electromagnetic fields, and residual gas have been implemented into the beam dynamics code TRACK. Estimates of the stripping losses along two high-intensity H{sup -} linacs are presented: the Spallation Neutron Source linac currently being operated at Oak Ridge National Laboratory and an 8 GeV superconducting linac currently being designed at Fermi National Accelerator Laboratory.

  16. Defects in metals. [Positron annihilation spectroscopy

    SciTech Connect

    Siegel, R.W.

    1982-06-01

    The application of positron annihilation spectroscopy (PAS) to the study of defects in metals has led to increased knowledge on lattice-defect properties during the past decade in two areas: the determination of atomic defect properties, particularly those of monovacancies, and the monitoring and characterization of vacancy-like microstructure development during post-irradiation and post-quench annealing. The study of defects in metals by PAS is reviewed within the context of the other available techniques for defect studies. The strengths and weaknesses of PAS as a method for the characterization of defect microstructures are considered. The additional possibilities for using the positron as a localized probe of the atomic and electronic structures of atomic defects are discussed, based upon theoretical calculations of the annihilation characteristics of defect-trapped positrons and experimental observations. Finally, the present status and future potential of PAS as a tool for the study of defects in metals is considered. 71 references, 9 figures.

  17. Trapped positrons observed by PAMELA experiment

    NASA Astrophysics Data System (ADS)

    Mikhailov, V. V.; Adriani, O.; Barbarino, G.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F. S.; Campana, D.; Carbone, R.; Carlson, P.; Casolino, M.; Castellini, G.; Consiglio, L.; De Santis, C.; De Simone, N.; Di Felice, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobsky, S.; Krutkov, S. Yu; Kvashnin, A. N.; Leonov, A. A.; Malakhov, V. V.; Marcelli, L.; Martucci, M.; Mayorov, A. G.; Menn, W.; Merge, M.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Papini, P.; Palma, F.; Panico, B.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Vacchi, A.; Vannuccini, E.; Vasiliev, G. I.; Voronov, S. A.; Yurkin, Yu T.; Zampa, G.; Zampa, N.

    2016-02-01

    Measurements of electron and positron spatial distributions in energy range from 80 MeV to several GeV below the geomagnetic cutoff rigidity were carried out using the PAMELA magnetic spectrometer. The instrument is installed on board the Resurs-DK satellite which was launched June 15th 2006 on an elliptical orbit with the inclination 70 degrees and the altitude 350-600 km. The procedure of trajectories calculations in the geomagnetic filed gives a way to separate stably trapped and short lived albedo components produced in interactions of cosmic ray protons with the residual atmosphere. The work presents spatial distributions of trapped, quasitrapped and short-lived albedo electrons and positrons in the near Earth space. Electron to positron ratio points out on different production mechanism of trapped and quasitrapped particles.

  18. High-Power Linac for the Spallation Neutron Source

    NASA Astrophysics Data System (ADS)

    Rej, D. J.

    2002-04-01

    The Spallation Neutron Source (SNS) will be the world’s most intense source of neutrons for fundamental science and industrial applications. Design and construction of this facility, located at Oak Ridge, is a joint venture between six DOE laboratories. Construction began in 1999 and is currently ahead of the scheduled 2006 completion date. Injecting a high-power, pulsed proton beam into a mercury target produces neutrons. In this talk, we review the physics requirements, design, and status of the construction of the 1-GeV, 1.4-MW average power RF linac for SNS. The accelerator consists of a drift tube linac (DTL), a coupled-cavity linac (CCL), and a superconducting rf (SRF) linac. The phase and quadrupole settings are set to avoid structure and parametric resonances, with coherent resonances posing minimal risk for emittance growth. The DTL is 37 m long and accelerates the ions to 87 MeV. The CCL is 55 m long and accelerates the ions to 186 MeV. The rf structure design and stability for both the DTL and CCL have been validated with scale models. The SRF linac has a modular design to accelerate ions to 1000 MeV, with a straightforward upgrade to 1.3 GeV at a later date. 3D particle-in-cell simulations of beam dynamics are performed to validate performance. The accelerator utilizes 93 MW of pulsed power operating continuously at 60-Hz with an 8factor. Approximately one hundred 402.5 or 805-MHz klystrons, with outputs between 0.55 and 5 MW, are used. The klystrons are powered by a novel converter-modulator that takes advantage of recent advances in IGBT switch plate assemblies and low-loss material cores for boost transformer. Beam diagnostics include position, phase, profile, and current monitors. They are designed to enable accurate beam steering and matching, and to minimize beam loss that would lead to activation and prevent hands-on maintenance.

  19. The Muon LINAC for the International Design Study of the Neutrino Factory

    SciTech Connect

    A. Kurup, C. Bontoiu, Morteza Aslaninejad, J. Pozimski, A. Bogacz, V.S. Morozov, Y.R. Roblin, K.B. Beard

    2011-09-01

    The first stage of muon acceleration in the Neutrino Factory utilises a superconducting linac to accelerate muons from 244 MeV to 900 MeV. The linac was split into three types of cryomodules with decreasing magnetic fields and increasing amounts of RF voltage but with the design of the superconducting solenoid and RF cavities being the same for all cryomodules. The current status of the muon linac for the International Design Study for the Neutrino Factory will be presented including a final lattice design of the linac and tracking simulations.

  20. The Boeing 120 MeV RF linac for FEL research

    SciTech Connect

    Adamski, J.L.; Gallagher, W.J.; Kennedy, R.C.; Robinson, B.; Shoffstall, D.R.; Tyson, E.L.; Vetter, A.M.; Yeremian, A.D.

    1985-10-01

    A new electron linac for high power, visible wavelength, free electron laser research is under construction at the Boeing Radiation Laboratory in Seattle. The linac is a five section, traveling wave, L band structure with a specialized ''comb'' pulse format of widely separated high charge micropulses. The paper describes the accelerator design and prototyping of key components of the linac. These include a double subharmonic injector and a long pulse phase and amplitude stabilized RF source which have been tested on Boeing's 20 MeV S band linac.

  1. Position-resolved Positron Annihilation Lifetime Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wagner, A.; Butterling, M.; Fiedler, F.; Fritz, F.; Kempe, M.; Cowan, T. E.

    2013-06-01

    A new method which allows for position-resolved positron lifetime spectroscopy studies in extended volume samples is presented. In addition to the existing technique of in-situ production of positrons inside large (cm3) bulk samples using high-energy photons up to 16 MeV from bremsstrahlung production, granular position-sensitive photon detectors have been employed. A beam of intense bremsstrahlung is provided by the superconducting electron linear accelerator ELBE (Electron Linear Accelerator with high Brilliance and low Emittance) which delivers electron bunches of less than 10 ps temporal width and an adjustable bunch separation of multiples of 38 ns, average beam currents of 1 mA, and energies up to 40 MeV. Since the generation of bremsstrahlung and the transport to the sample preserves the sharp timing of the electron beam, positrons generated inside the entire sample volume by pair production feature a sharp start time stamp for positron annihilation lifetime studies with high timing resolutions and high signal to background ratios due to the coincident detection of two annihilation photons. Two commercially available detectors from a high-resolution medial positron-emission tomography system are being employed with 169 individual Lu2SiO5:Ce scintillation crystals, each. In first experiments, a positron-lifetime gated image of a planar Si/SiO2 (pieces of 12.5 mm × 25 mm size) sample and a 3-D structured metal in Teflon target could be obtained proving the feasibility of a three dimensional lifetime-gated tomographic system.

  2. Development of Texas intense positron source

    NASA Astrophysics Data System (ADS)

    Köymen, A. R.; Ünlü, K.; Jacobsen, F. M.; Göktepeli, S.; Wehring, B. W.

    1999-02-01

    The Texas Intense Positron Source (TIPS) is a reactor-based low-energy positron beam facility utilizing some novel techniques in positron beam production. This facility will be located at the University of Texas (UT) at Austin Nuclear Engineering Teaching Laboratory (NETL) and is being developed by UT Austin and UT Arlington researchers. TIPS will use a large area (total area of 900-1800 cm 2) 64Cu source to supply fast β + particles for subsequent moderation to form an intense monoenergetic positron beam in the energy range of 0-50 keV with an expected intensity of 10 8 e +/s. Natural copper will be neutron activated near the core of the NETL 1 MW TRIGA Mark II research reactor to produce the 64Cu isotope. The activated source will be transported to the moderator/remoderator assembly, outside the biological shield of the reactor. This assembly combines the primary moderation and posterior remoderation of the fast β + particles into one stage using solid Kr to produce a low-energy positron source of a few eV with a diameter of 8 mm. The low-energy positron beam is then extracted by an electrostatic modified SOA gun and after further acceleration to 5 keV, the beam is focused onto the object slit of a 90° bending magnet. After further focusing and another 90° bend, the beam enters the main accelerator/decelerator that transports the beam onto the target for experimentation. The components of TIPS have been manufactured and are currently being optimized. In this communication we present some of the details of the TIPS facility and furthermore briefly discuss its intended applications.

  3. Positron Binding Properties of Glycine and Its Aqueous Complexes.

    PubMed

    Nummela, Mikko; Raebiger, Hannes; Yoshida, Daisuke; Tachikawa, Masanori

    2016-06-16

    We investigate positron binding to glycine and its aqueous complexes by first-principles calculation. We show that while glycine in its ground state (Gly) does not bind positrons, several of its strongly polar conformers do, and in particular, its zwitterion form (GlyZI) binds positrons strongly. Aqueous complexes Gly·nH2O and GlyZI·nH2O also bind positrons, if their dipole moment μ > μcr. However, μ is not a sufficient quantity to describe positron binding to these complexes. We show that in addition to μ, positron binding strongly depends on the intramolecular bonding of glycine. In Gly·nH2O, positrons are weakly bound to the nitrogen in Gly, whereas in GlyZI·nH2O, the ionic oxygen in GlyZI is a strong "positron attractor". PMID:27232201

  4. Apparatus for photon activation positron annihilation analysis

    DOEpatents

    Akers, Douglas W.

    2007-06-12

    Non-destructive testing apparatus according to one embodiment of the invention comprises a photon source. The photon source produces photons having predetermined energies and directs the photons toward a specimen being tested. The photons from the photon source result in the creation of positrons within the specimen being tested. A detector positioned adjacent the specimen being tested detects gamma rays produced by annihilation of positrons with electrons. A data processing system operatively associated with the detector produces output data indicative of a lattice characteristic of the specimen being tested.

  5. Heuristic theory of positron-helium scattering.

    NASA Technical Reports Server (NTRS)

    Drachman, R. J.

    1971-01-01

    An error in a previous modified adiabatic approximation (Drachman, 1966), due to a lack of generality in the form of the short-range correlation part of the wave function for L greater than zero, is corrected heuristically by allowing the monopole suppression parameter to depend on L. An L-dependent local potential is constructed to fit the well-known positron-hydrogen s, p, and d wave phase shifts below the rearrangement threshold. The same form of potential yields a positron-helium cross-section in agreement with a recent experimental measurement near threshold.

  6. Microstructural Characterization of Polymers with Positrons

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.

    1997-01-01

    Positrons provide a versatile probe for monitoring microstructural features of molecular solids. In this paper, we report on positron lifetime measurements in two different types of polymers. The first group comprises polyacrylates processed on earth and in space. The second group includes fully-compatible and totally-incompatible Semi-Interpenetrating polymer networks of thermosetting and thermoplastic polyimides. On the basis of lifetime measurements, it is concluded that free volumes are a direct reflection of physical/electromagnetic properties of the host polymers.

  7. Cold positrons from decaying dark matter

    NASA Astrophysics Data System (ADS)

    Boubekeur, Lotfi; Dodelson, Scott; Vives, Oscar

    2012-11-01

    Many models of dark matter contain more than one new particle beyond those in the Standard Model. Often, heavier particles decay into the lightest dark matter particle as the Universe evolves. Here, we explore the possibilities which arise if one of the products in a (heavyparticle)→(darkmatter) decay is a positron, and the lifetime is shorter than the age of the Universe. The positrons cool down by scattering off the cosmic microwave background and eventually annihilate when they fall into Galactic potential wells. The resulting 511 keV flux not only places constraints on this class of models, but might even be consistent with that observed by the INTEGRAL satellite.

  8. Positron emission tomography - a new approach to brain chemistry

    SciTech Connect

    Jacobson, H.G.

    1988-11-11

    Positron emission tomography permits examination of the chemistry of the brain in living beings. Until recently, positron emission tomography had been considered a research tool, but it is rapidly moving into clinical practice. This report describes the uses and applications of positron emission tomography in examinations of patients with strokes, epilepsy, malignancies, dementias, and schizophrenia and in basic studies of synaptic neurotransmission.

  9. Physics perspectives at JLab with a polarized positron beam

    SciTech Connect

    Voutier, Eric J.-M.

    2014-06-01

    Polarized positron beams are in some respect mandatory complements to polarized electron beams. The advent of the PEPPo concept for polarized positron production opens the possibility for the developement at the Jefferson Laboratory of a continuous polarized positron beam. The benefits of such a beam for hadronic structure studies are discussed, together with the technical and technological challenges to face.

  10. Propagation of solitary waves in relativistic electron-positron-ion plasmas with kappa distributed electrons and positrons

    SciTech Connect

    Shah, Asif; Mahmood, S.; Haque, Q.

    2011-11-15

    Electrostatic ion acoustic solitary waves are studied in a plasma system comprising of relativistic ions, kappa distributed electrons, and positrons. The increase in the relativistic streaming factor and positron and electron kappa parameters cause the soliton amplitude to thrive. However, the soliton amplitude diminishes as the positron concentration is increased in the system. Our results are general and may be helpful, in understanding nonlinear phenomena in the presence of kappa distibuted electrons, positrons, and relativistically streaming ions.

  11. Application of mathematical removal of positron range blurring in Positron Emission Tomography

    SciTech Connect

    Haber, S.F.; Derenzo, S.E.; Uber, D.

    1990-04-01

    The range of positrons in tissue is an important limitation to the ultimate spatial resolution achievable in Positron Emission Tomography. In this work we applied a Fourier deconvolution technique to remove range blurring in images taken by the Donner 600-Crystal Positron Tomograph. Using phantom data, we found significant improvement in the image quality and the FWHM for both {sup 68}Ga and {sup 82}Rb. These were successfully corrected so that the images and FWHM almost matched those of {sup 18}F which has negligible positron range. However, statistical noise was increased by the deconvolution process and it was not practical to recover the full spatial resolution of the tomograph. 10 refs., 6 figs., 3 tabs.

  12. Application of mathematical removal of positron range blurring in positron emission tomography

    SciTech Connect

    Haber, S.F.; Derenzo, S.E.; Uber, D. )

    1990-06-01

    The range of positrons in tissue is an important limitation to the ultimate spatial resolution achievable in positron emission tomography. In this work the authors have applied a Fourier deconvolution technique to remove range blurring in images taken by the Donner 600-crystal positron tomograph. Using phantom data, the authors have found significant improvement in the image quality and the FWHM for both {sup 68}Ga and {sup 82}Rb. These were successfully corrected so that the images and FWHM almost matched those of {sup 18}F which has negligible positron range. However, statistical noise was increased by the deconvolution process and it was not practical to recover the full spatial resolution of the tomograph.

  13. Positron Annihilation in the Bipositronium Ps2

    SciTech Connect

    Bailey, David H.; Frolov, Alexei M.

    2005-07-01

    The electron-positron-pair annihilation in the bipositronium PS2 is considered. In particular, the two-, three-, one- and zero-photon annihilation rates are determined to high accuracy. The corresponding analytical expressions are also presented. Also, a large number of bound state properties have been determined for this system.

  14. Advanced Instrumentation for Positron Emission Tomography [PET

    DOE R&D Accomplishments Database

    Derenzo, S. E.; Budinger, T. F.

    1985-04-01

    This paper summarizes the physical processes and medical science goals that underlay modern instrumentation design for Positron Emission Tomography. The paper discusses design factors such as detector material, crystalphototube coupling, shielding geometry, sampling motion, electronics design, time-of-flight, and the interrelationships with quantitative accuracy, spatial resolution, temporal resolution, maximum data rates, and cost.

  15. Positron elastic scattering from alkaline earth targets

    NASA Astrophysics Data System (ADS)

    Poveda, Luis A.; Assafrão, Denise; Mohallem, José R.

    2016-07-01

    A previously reported model potential approach [Poveda et al., Phys. Rev. A 87, 052702 (2013)] was extended to study low energy positron elastic scattering from beryllium and magnesium. The cross sections were computed for energies ranging from 10-5 eV up to well above the positronium formation threshold. The present results are in good agreement with previous reports, including the prediction of a p-wave resonance in the cross section for magnesium. The emergence of this shape resonance is connected to a trend observed in the evolution of the partial wave cross section in going from Be to Mg target. This trend lead us to speculate that a sharp d-wave resonance should be observed in positron elastic scattering from calcium. The positron-target binding energies are investigated in detail, both using the scattering information and by direct computation of the bound state energies using the model potentials. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2016-70120-y

  16. Excitation of helium ion by positron impact

    SciTech Connect

    Khan, P.; Ghosh, A.S.

    1986-01-01

    Three (1s,2s,2p) and five (1s,2s,2p,3s-bar,3p-bar) -state close-coupling methods have been employed to calculate the n = 2 excitation cross sections of helium ion by positron impact. The effect of pseudostate is found to be very pronounced in the case of 1s-2s excitation.

  17. Positrons observed to originate from thunderstorms

    NASA Astrophysics Data System (ADS)

    Fishman, Gerald J.

    2011-05-01

    Thunderstorms are the result of warm, moist air moving rapidly upward, then cooling and condensing. Electrification occurs within thunderstorms (as noted by Benjamin Franklin), produced primarily by frictional processes among ice particles. This leads to lightning discharges; the types, intensities, and rates of these discharges vary greatly among thunderstorms. Even though scientists have been studying lightning since Franklin's time, new phenomena associated with thunderstorms are still being discovered. In particular, a recent finding by Briggs et al. [2011], based on observations by the Gamma-Ray Burst Monitor (GBM) instrument on NASA's satellite-based Fermi Gamma-ray Space Telescope (Fermi), shows that positrons are also generated by thunderstorms. Positrons are the antimatter form of electrons—they have the same mass and charge as an electron but are of positive rather than negative charge; hence the name positron. Observations of positrons from thunderstorms may lead to a new tool for understanding the electrification and high-energy processes occurring within thunderstorms. New theories, along with new observational techniques, are rapidly evolving in this field.

  18. Positron Interactions with Atoms and Ions

    NASA Technical Reports Server (NTRS)

    Bhatia, Anand K.

    2012-01-01

    Dirac, in 1928, combining the ideas of quantum mechanics and the ideas of relativity invented the well-known relativistic wave equation. In his formulation, he predicted an antiparticle of the electron of spin n-bar/2. He thought that this particle must be a proton. Dirac published his interpretation in a paper 'A theory of electrons and protons.' It was shown later by the mathematician Hermann Weyl that the Dirac theory was completely symmetric between negative and positive particles and the positive particle must have the same mass as that of the electron. In his J. Robert Oppenheimer Memorial Prize Acceptance Speech, Dirac notes that 'Blackett was really the first person to obtain hard evidence for the existence of a positron but he was afraid to publish it. He wanted confirmation, he was really over cautious.' Positron, produced by the collision of cosmic rays in a cloud chamber, was detected experimentally by Anderson in 1932. His paper was published in Physical Review in 1933. The concept of the positron and its detection were the important discoveries of the 20th century. I have tried to discuss various processes involving interactions of positrons with atoms and ions. This includes scattering, bound states and resonances. It has not been possible to include the enormous work which has been carried out during the last 40 or 50 years in theory and measurements.

  19. First results of a positron microscope

    SciTech Connect

    Van House, J.; Rich, A.

    1988-01-18

    We have constructed a prototype transmission positron microscope (TPM) and taken magnified pictures of various objects with it. Information gained from the prototype TPM has allowed us to predict resolutions achievable in the near future using an upgraded TPM. Applications are discussed.

  20. New source of dense, cryogenic positron plasmas.

    PubMed

    Jørgensen, L V; Amoretti, M; Bonomi, G; Bowe, P D; Canali, C; Carraro, C; Cesar, C L; Charlton, M; Doser, M; Fontana, A; Fujiwara, M C; Funakoshi, R; Genova, P; Hangst, J S; Hayano, R S; Kellerbauer, A; Lagomarsino, V; Landua, R; Lodi Rizzini, E; Macrì, M; Madsen, N; Mitchard, D; Montagna, P; Rotondi, A; Testera, G; Variola, A; Venturelli, L; van der Werf, D P; Yamazaki, Y

    2005-07-01

    We have developed a new method, based on the ballistic transfer of preaccumulated plasmas, to obtain large and dense positron plasmas in a cryogenic environment. The method involves transferring plasmas emanating from a region with a low magnetic field (0.14 T) and relatively high pressure (10(-9) mbar) into a 15 K Penning-Malmberg trap immersed in a 3 T magnetic field with a base pressure better than 10(-13) mbar. The achieved positron accumulation rate in the high field cryogenic trap is more than one and a half orders of magnitude higher than the previous most efficient UHV compatible scheme. Subsequent stacking resulted in a plasma containing more than 1.2 x 10(9) positrons, which is a factor 4 higher than previously reported. Using a rotating wall electric field, plasmas containing about 20 x 10(6) positrons were compressed to a density of 2.6 x 10(10) cm(-3). This is a factor of 6 improvement over earlier measurements. PMID:16090691

  1. Positron source position sensing detector and electronics

    DOEpatents

    Burnham, Charles A.; Bradshaw, Jr., John F.; Kaufman, David E.; Chesler, David A.; Brownell, Gordon L.

    1985-01-01

    A positron source, position sensing device, particularly with medical applications, in which positron induced gamma radiation is detected using a ring of stacked, individual scintillation crystals, a plurality of photodetectors, separated from the scintillation crystals by a light guide, and high resolution position interpolation electronics. Preferably the scintillation crystals are several times more numerous than the photodetectors with each crystal being responsible for a single scintillation event from a received gamma ray. The light guide will disperse the light emitted from gamma ray absorption over several photodetectors. Processing electronics for the output of the photodetectors resolves the location of the scintillation event to a fraction of the dimension of each photodetector. Because each positron absorption results in two 180.degree. oppositely traveling gamma rays, the detection of scintillation in pairs permits location of the positron source in a manner useful for diagnostic purposes. The processing electronics simultaneously responds to the outputs of the photodetectors to locate the scintillations to the source crystal. While it is preferable that the scintillation crystal include a plurality of stacked crystal elements, the resolving power of the processing electronics is also applicable to continuous crystal scintillators.

  2. Laser Ponderomotive Electron-Positron Collider

    SciTech Connect

    Nakajima, Kazuhisa

    2004-12-07

    Relativistic ultrahigh laser fields can produce plasmas through quantum mechanical tunneling ionization mechanism, and accelerate produced electrons and ions to generate a relativistic electron beam and energetic ions in plasmas. This process will be followed by creation of electron-positron pairs through interaction of relativistic electrons with a Coulomb field of a nucleus in plasma ions or a strong laser field. In a relativistic strong laser field, the longitudinal accelerating force exerted on an electron is proportional to the square of the electric field, whereas the transverse quivering force is just linearly proportional to it. This is essence of the relativistic ponderomotive acceleration that dominantly produces energetic particles in interaction of ultraintese laser fields with particle beams and plasma. Therefore a tightly focused laser field can accelerate an electron-positron bunch longitudinally up to a remarkable energy and at the same time confines it transversely in the superposed ponderomotive potential of an intense ultrashort laser pulse. Here we propose acceleration and focusing of the electron-positron pair beam by the ponderomotive acceleration scheme to compose a high energy electron-positron collider with very high luminosity.

  3. TU-C-BRE-03: Aggregation of Linac Measurement Data

    SciTech Connect

    Kerns, J; Alvarez, P; Followill, D; Lowenstein, J; Molineu, A; Summers, P; Kry, S

    2014-06-15

    Purpose: Accurate data of linear accelerator radiation characteristics is important for treatment planning system commissioning as well as regular quality assurance of the machine. The RPC has performed site visits of numerous machines . Data gathered from Varian machines from the past 15 years are presented. The data collected can be used as a secondary check or when commissioning a new machine to verify that values are reasonable. Methods: Data from the past 15 years of RPC site visits was compiled and analyzed. Data was composed from measurements from approximately 400 Varian machines. Each dataset consists of several point measurements at various locations in a water phantom to measure percentage depth dose, output factors, including small MLC fields, off-axis factors, and wedge factors if applicable. Common statistical values are presented for each machine type. Where applicable, data was compared to other reference data given by the vendor or a select number of previous researchers. Results: Data is separated by energy and parameter and then analyzed by machine class. Data distributions of the parameter data were normal except occasionally at the tails. Distributions of the data for each class and parameter are tabulated to give not simply a singular reference value, but metrics about the distribution: 5th and 95th percentile values and the standard deviation as well as the median. Conclusion: The RPC has collected numerous data on Varian linacs and presented the finding of the past 15 years. The data can be used as a reference data set for physicists to compare against. A linac that deviates from the values does not necessarily indicate there is a problem as long as the treatment planning system correlates to the machine. Comparison of linac and treatment planning system data to external reference data can prevent serious treatment errors.

  4. Large dynamic range diagnostics for high current electron LINACs

    SciTech Connect

    Evtushenko, P.

    2013-11-07

    The Jefferson Lab FEL driver accelerator - Energy Recovery Linac has provided a beam with average current of up to 9 mA and beam energy of 135 MeV. The high power beam operations have allowed developing and testing methods and approaches required to set up and tune such a facility simultaneously for the high beam power and high beam quality required for high performance FEL operations. In this contribution we briefly review this experience and outline problems that are specific to high current - high power non-equilibrium linac beams. While the original strategy for beam diagnostics and tuning have proven to be quite successful, some shortcomings and unresolved issues were also observed. The most important issues are the non-equilibrium (non-Gaussian) nature of the linac beam and the presence of small intensity - large amplitude fraction of the beam a.k.a. beam halo. Thus we also present a list of the possible beam halo sources and discuss possible mitigations means. We argue that for proper understanding and management of the beam halo large dynamic range (>10{sup 6}) transverse and longitudinal beam diagnostics can be used. We also present results of transverse beam profile measurements with the dynamic range approaching 10{sup 5} and demonstrate the effect the increased dynamic range has on the beam characterization, i.e., emittance and Twiss parameters measurements. We also discuss near future work planned in this field and where the JLab FEL facility will be used for beam tests of the developed of new diagnostics.

  5. Large dynamic range diagnostics for high current electron LINACs

    SciTech Connect

    Evtushenko, Pavel

    2013-11-01

    The Jefferson Lab FEL driver accelerator - Energy Recovery Linac has provided a beam with average current of up to 9 mA and beam energy of 135 MeV. The high power beam operations have allowed developing and testing methods and approaches required to set up and tune such a facility simultaneously for the high beam power and high beam quality required for high performance FEL operations. In this contribution we briefly review this experience and outline problems that are specific to high current - high power non-equilibrium linac beams. While the original strategy for beam diagnostics and tuning have proven to be quite successful, some shortcomings and unresolved issues were also observed. The most important issues are the non-equilibrium (non-Gaussian) nature of the linac beam and the presence of small intensity - large amplitude fraction of the beam a.k.a. beam halo. Thus we also present a list of the possible beam halo sources and discuss possible mitigations means. We argue that for proper understanding and management of the beam halo large dynamic range (>10{sup 6}) transverse and longitudinal beam diagnostics can be used. We also present results of transverse beam profile measurements with the dynamic range approaching 10{sup 5} and demonstrate the effect the increased dynamic range has on the beam characterization, i.e., emittance and Twiss parameters measurements. We also discuss near future work planned in this field and where the JLab FEL facility will be used for beam tests of the developed of new diagnostics.

  6. Status of the Kansas State University superconducting linac project

    NASA Astrophysics Data System (ADS)

    Gray, Tom J.

    1986-05-01

    Funding for the construction of the superconducting linac at Kansas State University was approved by the Department of Energy on May 15, 1985. The project is funded out of the Division of Chemical Sciences, USDOE. Initial design and staff technical training was initiated during 1984-85 with laboratory personnel working at both Florida State University and Argonne National Laboratory. The linac under construction is based upon the Nb split-ring resonator technology developed at Argonne National Laboratory for ATLAS. The linac at Kansas State University will have 14 superconducting resonators with nine low-β (β=0.06) and five high-β (β=0.105) units operating at 97 MHz. Work has progressed on both of the single-resonator cryostats for time bunching and energy rebunching, respectively, with the major cryostat components presently under construction by C. E. Raymond Enterprise Manufacturing, a division of Combustion Engineering, with scheduled delivery of the single resonator cryostat vacuum housings, LN2-cooled heat shields, and LHe Dewars on January 17, 1986. Orders for all Nb-clad Cu resonators have been placed with Argonne National Laboratory and two low-β units are currently under construction. Requests for quotations for a 300-W LHe refrigerator (expandable to 500 W) 1000-l storage Dewar and LHe distribution system have been issued. The building addition which includes a new accelerator/experimental hall (˜6000 ft2 basement structure) and ground-level laboratory support space including additional experimental setup space, additional machine shop space, and mechanical equipment space, is currently under construction with a completion date scheduled for May 1986. Additional personnel training on LHe refrigeration systems is scheduled for January 1986, at the Texas Accelerator Center and at Florida State University.

  7. Positron annihilation studies of moisture in graphite-reinforced composites

    SciTech Connect

    Singh, J.J.; Holt, W.H.; Mock, W., Jr.

    1980-07-01

    The positron lifetime technique of monitoring absorbed moisture is applied to several composites, including graphite/polymides which are candidates for high-temperature (over 260 C) applications. The experimental setup is a conventional fast-slow coincidence system wherein the positron lifetime is measured with respect to a reference time determined by the detection of a nuclear gamma ray emitted simultaneously with the positron. From the experiments, a rate of change of positron mean lifetime per unit mass of water can be determined for each type of specimen. Positron lifetime spectra are presented for a graphite/polyimide composite and for a pure polyimide.

  8. Positron annihilation studies of moisture in graphite-reinforced composites

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Holt, W. H.; Mock, W., Jr.; Buckingham, R. D.

    1980-01-01

    The positron lifetime technique of monitoring absorbed moisture is applied to several composites, including graphite/polymides which are candidates for high-temperature (over 260 C) applications. The experimental setup is a conventional fast-slow coincidence system wherein the positron lifetime is measured with respect to a reference time determined by the detection of a nuclear gamma ray emitted simultaneously with the positron. From the experiments, a rate of change of positron mean lifetime per unit mass of water can be determined for each type of specimen. Positron lifetime spectra are presented for a graphite/polyimide composite and for a pure polyimide.

  9. Relativistic Positron Creation Using Ultra-Intense Short Pulse Lasers

    SciTech Connect

    Chen, H; Wilks, S; Bonlie, J; Liang, E; Myatt, J; Price, D; Meyerhofer, D; Beiersdorfer, P

    2008-08-25

    We measure up to 2 x 10{sup 10} positrons per steradian ejected out the back of {approx}mm thick gold targets when illuminated with short ({approx} 1 ps) ultra-intense ({approx} 1 x 10{sup 20} W/cm{sup 2}) laser pulses. Positrons produced predominately by the Bethe-Heitler process and have an effective temperature of 2-4 MeV, with the distribution peaking at 4-7 MeV. The angular distribution of the positrons is anisotropic. The measurements indicate the laser produced, relativistic positron densities ({approx} 10{sup 16} positrons/cm{sup 3}) are the highest ever created in the laboratory.

  10. Use of the delta-t method for setting rf phase and amplitude for the AHF linac

    SciTech Connect

    Swain, G.R.

    1989-01-01

    The delta-t procedure is a time-of-flight method of finding set points for the rf phase and amplitude for each module of a linac. Expected errors for LAMPF afterburner linacs which might be used for an advanced hadron facility (AHF) are calculated. The modified delta-t procedure used on modules 13 through 48 of the present linac appears adequate to set up the proposed AHF linacs. 24 refs., 7 figs., 1 tab.

  11. Dedicated Linac for Radioneurosurgery at the National Institute of Neurology and Neurosurgery of Mexico

    NASA Astrophysics Data System (ADS)

    Celis-López, Miguel A.; Lárraga-Gutiérrez, José M.

    2003-09-01

    The objective is to present a description and the main clinical applications of this dedicated Linac for benign and malignant tumors in the central nervous system. The Novalis (BrainLab, Germany) is a 6 MV dedicated linac for a single high dose Radiosurgery (RS) and for fractionated doses in Stereotactic Radiotherapy with a high level of precision at the isocenter.

  12. WE-D-BRD-01: Innovation in Radiation Therapy Delivery: Advanced Digital Linac Features

    SciTech Connect

    Xing, L; Wong, J; Li, R

    2014-06-15

    Last few years has witnessed significant advances in linac technology and therapeutic dose delivery method. Digital linacs equipped with high dose rate FFF beams have been clinically implemented in a number of hospitals. Gated VMAT is becoming increasingly popular in treating tumors affected by respiratory motion. This session is devoted to update the audience with these technical advances and to present our experience in clinically implementing the new linacs and dose delivery methods. Topics to be covered include, technical features of new generation of linacs from different vendors, dosimetric characteristics and clinical need for FFF-beam based IMRT and VMAT, respiration-gated VMAT, the concept and implementation of station parameter optimized radiation therapy (SPORT), beam level imaging and onboard image guidance tools. Emphasis will be on providing fundamental understanding of the new treatment delivery and image guidance strategies, control systems, and the associated dosimetric characteristics. Commissioning and acceptance experience on these new treatment delivery technologies will be reported. Clinical experience and challenges encountered during the process of implementation of the new treatment techniques and future applications of the systems will also be highlighted. Learning Objectives: Present background knowledge of emerging digital linacs and summarize their key geometric and dosimetric features. SPORT as an emerging radiation therapy modality specifically designed to take advantage of digital linacs. Discuss issues related to the acceptance and commissioning of the digital linacs and FFF beams. Describe clinical utility of the new generation of digital linacs and their future applications.

  13. Nuclear burning-up of RAW in blanket of linac-driven

    SciTech Connect

    Beljakov, M.S.; Logashev, O.N.; Lopatkin, A.V.; Tocheny, L.V.; Khrjastov, H.A.; Blagovolin, P.P.; Kazaritsky, V.D.

    1993-12-31

    The progress in the field of designing and constructing a heavy-current proton linear accelerator became noticeable last year and allows one to count on large-scale industrial linac application. Symbiosis of linac and subcritical reactor as target has new opportunities for energetics. This accelerator concept is described.

  14. LHC and VLHC Based ep Colliders: e-Linac versus e-Ring

    NASA Astrophysics Data System (ADS)

    Gladilin, L.; Karadeniz, H.; Recepoglu, E.; Sultansoy, S.

    2007-06-01

    Linac-ring analogues of the LHC and VLHC based standard type ep collider proposals are discussed. It is shown that sufficiently high luminosities can be obtained with TESLA like linacs, whereas essential modifications are required for CLIC technology. The physics search potential of proposed ep colliders is demonstrated using pair production of heavy quarks as an example.

  15. Beam position monitor readout and control in the SLC linac

    SciTech Connect

    Bogart, J.; Phinney, N.; Ross, M.; Yaffe, D.

    1985-04-01

    A beam position monitoring system has been implemented in the first third of the SLC linac which provides a complete scan of the trajectory on a single beam pulse. The data is collected from the local micro-computers and viewed with an updating display at a console or passed on to application programs. The system must operate with interlaced beams so the scans are also interlaced, providing each user with the ability to select the beam, the update rate, and the attenuation level in the digitizing hardware. In addition each user calibrates the hardware for his beam. A description of the system architecture will be presented. 6 refs., 4 figs.

  16. Neutron Spectra and H*(10) in a 15 MV Linac

    SciTech Connect

    Benites, J.; Vega-Carrillo, H. R.; Hernandez-Davila, V. M.; Rivera, T.; Carrillo, A.; Mondragon, R.

    2010-12-07

    Neutron spectra and the ambient dose equivalent were calculated inside the bunker of a 15 MV Varian linac model CLINAC iX. Calculations were carried out using Monte Carlo methods. Neutron spectra in the vicinity of isocentre show the presence of evaporation and knock-on neutrons produced by the source term, while epithermal and thermal neutron remain constant regardless the distance respect to isocentre, due to room return. Along the maze neutron spectra becomes softer as the detector moves along the maze. The ambient dose equivalent is decreased but do not follow the 1/r{sup 2} rule due to changes in the neutron spectra.

  17. Tools to Predict Beam Breakup in Recirculating Linacs

    SciTech Connect

    Kevin Beard; Nikolitsa Merminga; Byung Yunn

    2003-05-01

    An important limitation on the maximum beam current in a recirculating linac is due to beam breakup caused by higher order modes (HOM) excited in the RF cavities. A HOM delivers a transverse kick to a beam bunch, the bunch on the next pass can then drive the HOM and cause it to grow until the beam is lost. Two codes, MATBBU1 and TDBBU2, have been written to estimate the threshold current for a set of HOMs and accelerator optics. The relative merits and limitations of each is discussed in detail.

  18. SARAF Phase I linac operation in 2013-2014

    NASA Astrophysics Data System (ADS)

    Weissman, L.; Berkovits, D.; Arenshtam, A.; Ben-Aliz, Y.; Buzaglo, Y.; Dudovitch, O.; Eisen, Y.; Eliyahu, I.; Feinberg, G.; Fishman, I.; Gertz, I.; Grin, A.; Halfon, S.; Har-Even, D.; Haruvy, Y. F.; Hirschmann, D.; Hirsh, T.; Horovitz, Z.; Kaizer, B.; Kijel, D.; Kreisel, A.; Luner, Y.; Mor, I.; Paul, M.; Perry, A.; Rodnizki, J.; Shimel, G.; Shor, A.; Silverman, I.; Tessler, M.; Vaintraub, S.

    2015-10-01

    Phase I of the SARAF superconducting RF linac is under operation at the Soreq Nuclear Research Center. The present status of Phase I main components is reported, as well as, the beam operation experience accumulated in 2013-2014. The latter include acceleration of a 2 mA and 1.6 mA CW proton beams at energies of 2 MeV and 3.9 MeV correspondingly and 1 mA pulsed, duty cycle of few %, deuteron beams up to 5.6 MeV. The recent experiments include operation of intense CW proton beams on the liquid lithium target.

  19. Optical laser systems at the Linac Coherent Light Source

    DOE PAGESBeta

    Minitti, Michael P.; Robinson, Joseph S.; Coffee, Ryan N.; Edstrom, Steve; Gilevich, Sasha; Glownia, James M.; Granados, Eduardo; Hering, Philippe; Hoffmann, Matthias C.; Miahnahri, Alan; et al

    2015-04-22

    Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS.

  20. OPERATIONAL ASPECTS OF HIGH POWER ENERGY RECOVERY LINACS

    SciTech Connect

    Stephen Benson; David Douglas; Pavel Evtushenko; Kevin Jordan; George Neil; Paul Powers

    2006-08-21

    We have been operating a high-power energy-recovery linac (ERL) at Jefferson Lab for several years. In the process we have learned quite a bit about both technical and physics limitations in high power ERLs. Several groups are now considering new ERLs that greatly increase either the energy, the current or both. We will present some of our findings on what to consider when designing, building, and operating a high power ERL. Our remarks for this paper are limited to lattice design and setup, magnets, vacuum chamber design, diagnostics, and beam stability.

  1. An application of the RFQ Linac: Nuclear waste assay characterization

    NASA Astrophysics Data System (ADS)

    Lamkin, K.; Schultz, F.; Womble, P.; Humphrey, D.; Vourvopoulos, G.

    1997-02-01

    A collaboration between Oak Ridge National Laboratory and Western Kentucky University examines the problem of characterization and assay of nuclear waste with high intrinsic neutron and gamma-ray fields. This waste is defined as Remote Handled-Transuranic waste (RH-TRU). A Radiofrequency Quadrupole Linac is used to produce pulses of neutrons, which impinge on the drum that contains the nuclear waste. The neutrons, after being thermalized in the matrix of the drum, are captured by the fissile material (239Pu or 235U), which releases fast neutrons upon fission. Experimental results will be presented to show the versatility of employing the RFQ with the Differential Die-away Technique.

  2. HINS Linac front end focusing system R&D

    SciTech Connect

    Apollinari, G.; Carcagno, R.H.; Dimarco, J.; Huang, Y.; Kashikhin, V.V.; Orris, D.F.; Page, T.M.; Rabehl, R.; Sylvester, C.; Tartaglia, M.A.; Terechkine, I.; /Fermilab /Argonne

    2008-08-01

    This report summarizes current status of an R&D program to develop a focusing system for the front end of a superconducting RF linac. Superconducting solenoids will be used as focusing lenses in the low energy accelerating sections of the front end. The development of focusing lenses for the first accelerating section is in the production stage, and lens certification activities are in preparation at FNAL. The report contains information about the focusing lens design and performance, including solenoid, dipole corrector, and power leads, and about cryogenic system design and performance. It also describes the lens magnetic axis position measurement technique and discusses scope of an acceptance/certification process.

  3. AMPERE AVERAGE CURRENT PHOTOINJECTOR AND ENERGY RECOVERY LINAC.

    SciTech Connect

    BEN-ZVI,I.; BURRILL,A.; CALAGA,R.; ET AL.

    2004-08-17

    High-power Free-Electron Lasers were made possible by advances in superconducting linac operated in an energy-recovery mode. In order to get to much higher power levels, say a fraction of a megawatt average power, many technological barriers are yet to be broken. We describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun employing a new secondary-emission multiplying cathode, an accelerator cavity, both capable of producing of the order of one ampere average current and plans for an ERL based on these units.

  4. The Development of the Linac Coherent Light Source RF Gun

    SciTech Connect

    Dowell, David H.; Jongewaard, Erik; Lewandowski, James; Limborg-Deprey, Cecile; Li, Zenghai; Schmerge, John; Vlieks, Arnold; Wang, Juwen; Xiao, Liling; /SLAC

    2008-09-24

    The Linac Coherent Light Source (LCLS) is the first x-ray laser user facility based upon a free electron laser (FEL) requiring extraordinary beam quality to saturate at 1.5 angstroms within a 100 meter undulator.[1] This new type of light source is using the last kilometer of the three kilometer linac at SLAC to accelerate the beam to an energy as high as 13.6 GeV and required a new electron gun and injector to produce a very bright beam for acceleration. At the outset of the project it was recognized that existing RF guns had the potential to produce the desired beam but none had demonstrated it. Therefore a new RF gun or at least the modification of an existing gun was necessary. The parameters listed in Table 1 illustrate the unique characteristics of LCLS which drive the requirements for the electron gun as given in Table 2. The gun beam quality needs to accommodate emittance growth as the beam is travels through approximately one kilometer of linac and two bunch compressors before reaching the undulator. These beam requirements were demonstrated during the recent commissioning runs of the LCLS injector and linac [2] due to the successful design, fabrication, testing and operation of the LCLS gun. The goal of this paper is to relate the technical background of how the gun was able to achieve and in some cases exceed these requirements by understanding and correcting the deficiencies of the prototype s-band RF photocathode gun, the BNL/SLAC/UCLA Gun III. This paper begins with a brief history and technical description of Gun III and the Gun Test Facility (GTF) at SLAC, and studies of the gun's RF and emittance compensation solenoid. The work at the GTF identified the gun and solenoid deficiencies, and helped to define the specifications for the LCLS gun. Section 1.1.5 describes the modeling used to compute and correct the gun RF fields and Section 1.1.6 describes the use of these fields in the electron beam simulations. The magnetic design and measurements of

  5. A microwave power driver for linac colliders: Gigatron

    SciTech Connect

    Bizek, H.M.; Elliott, S.M.; McIntyre, P.M.; Nassiri, A.; Popovic, M.B.; Raparia, D.; Gray, H.F. . Dept. of Physics; Naval Research Lab., Washington, DC )

    1988-11-18

    The gigatron is a new rf amplifier tube designed for linac collider applications. Three design features permit extension of the lasertron concept to very high frequencies. First, a gated field-emitter array is employed for the modulated cathode. Second, a ribbon beam geometry mitigates space charge depression and facilitates efficient output coupling. Third, a traveling wave output coupler is used to obtain optimum coupling to the ribbon beam. This paper describes recent developments in the gigatron design, and progress towards experimental tests. 9 refs., 8 figs., 1 tab.

  6. Optical laser systems at the Linac Coherent Light Source

    PubMed Central

    Minitti, Michael P.; Robinson, Joseph S.; Coffee, Ryan N.; Edstrom, Steve; Gilevich, Sasha; Glownia, James M.; Granados, Eduardo; Hering, Philippe; Hoffmann, Matthias C.; Miahnahri, Alan; Milathianaki, Despina; Polzin, Wayne; Ratner, Daniel; Tavella, Franz; Vetter, Sharon; Welch, Marc; White, William E.; Fry, Alan R.

    2015-01-01

    Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS. PMID:25931064

  7. Radiation protection of linac bunkers. A user-friendly approach.

    PubMed

    Sørensen, Thyge Holten; Olsen, Kjeld Jørgen; Behrens, Claus Flensted

    2015-07-01

    A well-known but complex formalism for the calculation of the leakage dose at the entrance of the linac maze was considered and simplified. These simplifications were based partly on the literature and partly on the authors' own measurements. The authors have included photon scatter originating from the irradiated patient in the formalism. A formalism for two different types of bunkers was developed, and the authors have obtained simple formulas to calculate the dose at the maze entrance for both bunker types. PMID:25836699

  8. Analysis of beam loss mechanism in the Project X linac

    SciTech Connect

    Carneiro, J.-P.; Lebedev, V.; Nagaitsev, S.; Ostiguy, J.-F.; Solyak, N.; /Fermilab

    2011-03-01

    Minimization of the beam losses in a multi-MW H{sup -} linac such as ProjectX to a level below 1 W/m is a challenging task. The impact of different mechanism of beam stripping, including stripping in electric and magnetic fields, residual gas, blackbody radiation and intra-beam stripping, is analyzed. Other sources of beam losses are misalignements of beamline elements and errors in RF fields and phases. We present in this paper requirements for dynamic errors and correction schemes to keep beam losses under control.

  9. Cumulative beam breakup in radio-frequency linacs

    SciTech Connect

    Bohn, C.L.; Delayen, J.R.

    1990-01-01

    An analytic model of cumulative beam breakup has been developed which is applicable to both low-velocity ion and high-energy electron linear accelerators. The model includes arbitrary velocity, acceleration, focusing, initial conditions, beam-cavity resonances, and variable cavity geometry and spacing along the accelerator. The model involves a continuum approximation'' in which the transverse kicks in momentum imparted by the cavities are smoothed over the length of the linac. The resulting equation of transverse motion is solved via the WKBJ method. Specific examples are discussed which correspond to limiting cases of the solution. 16 refs.

  10. Acceleration units for the Induction Linac Systems Experiment (ILSE)

    SciTech Connect

    Faltens, A.; Brady, V.; Brodzik, D.; Hansen, L.; Laslett, L.J.; Mukherjee, S.; Bubp, D.; Ravenscroft, D.; Reginato, L.

    1989-03-01

    The design of a high current heavy ion induction linac driver for inertial confinement fusion is optimized by adjusting the acceleration units along the length of the accelerator to match the beam current, energy, and pulse duration at any location. At the low energy end of the machine the optimum is a large number of electrostatically focused parallel beamlets, whereas at higher energies the optimum is a smaller number of magnetically focused beams. ILSE parallels this strategy by using 16 electrostatically focused beamlets at the low end followed by 4 magnetically focused beams after beam combining. 3 refs., 2 figs.

  11. Emittance of positron beams produced in intense laser plasma interaction

    SciTech Connect

    Chen Hui; Hazi, A.; Link, A.; Anderson, S.; Gronberg, J.; Izumi, N.; Tommasini, R.; Wilks, S.; Sheppard, J. C.; Meyerhofer, D. D.; Baldis, H. A.; Marley, E.; Park, J.; Williams, G. J.; Fedosejev, R.; Kerr, S.

    2013-01-15

    The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm{center_dot}mrad, comparable to the positron sources used at existing accelerators. With 10{sup 10}-10{sup 12} positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5-20 MeV, may be useful as an alternative positron source for future accelerators.

  12. Positron Beam Propagation in a Meter Long Plasma Channel

    SciTech Connect

    Marsh, K.A.; Blue, B.E.; Clayton, C.E.; Joshi, C.; Mori, W.B.; Decker, F.-J.; Hogan, M.J.; Iverson, R.; O'Connell, C.; Raimondi, P.; Siemann, Robert H.; Walz, D.; Katsouleas, T.C.; Muggli, P.; /Southern California U.

    2008-03-17

    Recent experiments and simulations have shown that positron beams propagating in plasmas can be focused and also create wakes with large accelerating gradients. For similar parameters, the wakes driven by positron beams are somewhat smaller compared to the case of an electron beam. Simulations have shown that the wake amplitude can be increased if the positron beam is propagated in a hollow plasma channel (Ref. 1). This paper, compares experimentally, the propagation and beam dynamics of a positron beam in a meter scale homogeneous plasma, to a positron beam hollow channel plasma. The results show that positron beams in hollow channels are less prone to distortions and deflections. Hollow channels were observed to guide the positron beam onto the channel axis. Beam energy loss was also observed implying the formation of a large wake amplitude. The experiments were carried out as part of the E-162 plasma wakefield experiments at SLAC.

  13. PREFACE: The International Workshop on Positron Studies of Defects 2014

    NASA Astrophysics Data System (ADS)

    Sugita, Kazuki; Shirai, Yasuharu

    2016-01-01

    The International Workshop on Positron Studies of Defects 2014 (PSD-14) was held in Kyoto, Japan from 14-19 September, 2014. The PSD Workshop brought together positron scientists interested in studying defects to an international platform for presenting and discussing recent results and achievements, including new experimental and theoretical methods in the field. The workshop topics can be characterized as follows: • Positron studies of defects in semiconductors and oxides • Positron studies of defects in metals • New experimental methods and equipment • Theoretical calculations and simulations of momentum distributions, positron lifetimes and other characteristics for defects • Positron studies of defects in combination with complementary methods • Positron beam studies of defects at surfaces, interfaces, in sub-surface regions and thin films • Nanostructures and amorphous materials

  14. Methods and apparatus for producing and storing positrons and protons

    DOEpatents

    Akers, Douglas W.

    2010-07-06

    Apparatus for producing and storing positrons may include a trap that defines an interior chamber therein and that contains an electric field and a magnetic field. The trap may further include a source material that includes atoms that, when activated by photon bombardment, become positron emitters to produce positrons. The trap may also include a moderator positioned adjacent the source material. A photon source is positioned adjacent the trap so that photons produced by the photon source bombard the source material to produce the positron emitters. Positrons from the positron emitters and moderated positrons from the moderator are confined within the interior chamber of the trap by the electric and magnetic fields. Apparatus for producing and storing protons are also disclosed.

  15. High-yield positron systems for linear colliders

    SciTech Connect

    Clendenin, J.E.

    1989-04-01

    Linear colliders, such as the SLC, are among those accelerators for which a high-yield positron source operating at the repetition rate of the accelerator is desired. The SLC, having electron energies up to 50 GeV, presents the possibility of generating positron bunches with useful charge even exceeding that of the initial electron bunch. The exact positron yield to be obtained depends on the particular capture, transport and damping system employed. Using 31 GeV electrons impinging on a W-type converter phase-space at the target to the acceptance of the capture rf section, the SLC source is capable of producing, for every electron, up to two positrons within the acceptance of the positron damping ring. The design of this source and the performance of the positron system as built are described. Also, future prospects and limitations for high-yield positron systems are discussed. 11 refs., 5 figs., 3 tabs.

  16. Overview and Status Update of the Fermilab HINS Linac R&D Program

    SciTech Connect

    Webber, R.C.; Apollinari, G.; /Fermilab

    2009-05-01

    The Fermilab High Intensity Neutrino Source (HINS) Linac R&D program is continuing efforts to construct a first-of-a-kind superconducting H{sup -} linac. The goal of the HINS linac is to demonstrate, for the first time, acceleration of high intensity beam with superconducting spoke cavities, control of beam halo growth by use of solenoidal focusing optics throughout, and operation of many cavities from a single high-power RF source for acceleration of non-relativistic particles. The HINS effort is relevant to any future high brightness, high intensity linac and, in particular, to the linac proposed as part of Fermilab Project X to serve the next generation of neutrino physics and future muon storage ring/collider experiments. This paper updates the technical status of the various components being developed, built, and commissioned as a part of HINS and presents the outlook for the HINS program.

  17. Clinical applications with the HIDAC positron camera

    NASA Astrophysics Data System (ADS)

    Frey, P.; Schaller, G.; Christin, A.; Townsend, D.; Tochon-Danguy, H.; Wensveen, M.; Donath, A.

    1988-06-01

    A high density avalanche chamber (HIDAC) positron camera has been used for positron emission tomographic (PET) imaging in three different human studies, including patients presenting with: (I) thyroid diseases (124 cases); (II) clinically suspected malignant tumours of the pharynx or larynx (ENT) region (23 cases); and (III) clinically suspected primary malignant and metastatic tumours of the liver (9 cases, 19 PET scans). The positron emitting radiopharmaceuticals used for the three studies were Na 124I (4.2 d half-life) for the thyroid, 55Co-bleomycin (17.5 h half-life) for the ENT-region and 68Ga-colloid (68 min half-life) for the liver. Tomographic imaging was performed: (I) 24 h after oral Na 124I administration to the thyroid patients, (II) 18 h after intraveneous administration of 55Co-bleomycin to the ENT patients and (III) 20 min following the intraveneous injection of 68Ga-colloid to the liver tumour patients. Three different imaging protocols were used with the HIDAC positron camera to perform appropriate tomographic imaging in each patient study. Promising results were obtained in all three studies, particularly in tomographic thyroid imaging, where a significant clinical contribution is made possible for diagnosis and therapy planning by the PET technique. In the other two PET studies encouraging results were obtained for the detection and precise localisation of malignant tumour disease including an estimate of the functional liver volume based on the reticulo-endothelial-system (RES) of the liver, obtained in vivo, and the three-dimensional display of liver PET data using shaded graphics techniques. The clinical significance of the overall results obtained in both the ENT and the liver PET study, however, is still uncertain and the respective role of PET as a new imaging modality in these applications is not yet clearly established. To appreciate the clinical impact made by PET in liver and ENT malignant tumour staging needs further investigation

  18. Linac Alignment Algorithm: Analysis on 1-to-1 Steering

    SciTech Connect

    Sun, Yipeng; Adolphsen, Chris; /SLAC

    2011-08-19

    In a linear accelerator, it is important to achieve a good alignment between all of its components (such as quadrupoles, RF cavities, beam position monitors et al.), in order to better preserve the beam quality during acceleration. After the survey of the main linac components, there are several beam-based alignment (BBA) techniques to be applied, to further optimize the beam trajectory and calculate the corresponding steering magnets strength. Among these techniques the most simple and straightforward one is the one-to-one (1-to-1) steering technique, which steers the beam from quad center to center, and removes the betatron oscillation from quad focusing. For a future linear collider such as the International Linear Collider (ILC), the initial beam emittance is very small in the vertical plane (flat beam with {gamma}{epsilon}{sub y} = 20-40nm), which means the alignment requirement is very tight. In this note, we evaluate the emittance growth with one-to-one correction algorithm employed, both analytically and numerically. Then the ILC main linac accelerator is taken as an example to compare the vertical emittance growth after 1-to-1 steering, both from analytical formulae and multi-particle tracking simulation. It is demonstrated that the estimated emittance growth from the derived formulae agrees well with the results from numerical simulation, with and without acceleration, respectively.

  19. Delivery efficiency of an Elekta linac under gated operation.

    PubMed

    Cui, Guoqiang; Housley, David J; Chen, Fan; Mehta, Vivek K; Shepard, David M

    2014-01-01

    In this study, we have characterized the efficiency of an Elekta linac in the delivery of gated radiotherapy. We have explored techniques to reduce the beam-on delay and to improve the delivery efficiency, and have investigated the impact of frequent beam interruptions on the dosimetric accuracy of gated deliveries. A newly available gating interface was installed on an Elekta Synergy. Gating signals were generated using a surface mapping system in conjunction with a respiratory motion phantom. A series of gated deliveries were performed using volumetric modulated arc therapy (VMAT) treatment plans previously generated for lung cancer patients treated with stereotactic body radiotherapy. Baseline values were determined for the delivery times. The machine was then tuned in an effort to minimize beam-on delays and improve delivery efficiency. After that process was completed, the dosimetric accuracy of the gated deliveries was evaluated by comparing the measured and the planned coronal dose distributions using gamma index analyses. Comparison of the gated and the non-gated deliveries were also performed. The results demonstrated that, with the optimal machine settings, the average beam-on delay was reduced to less than 0.22 s. High dosimetric accuracy was demonstrated with gamma index passing rates no lower than 99.0% for all tests (3%/3 mm criteria). Consequently, Elekta linacs can provide a practical solution for gated VMAT treatments with high dosimetric accuracy and only a moderate increase in the overall delivery time. PMID:25207561

  20. Linac cryogenic distribution system maintenance and upgrades at Jlab

    SciTech Connect

    Dixon, Kelly D.; Wright, Mathew C.; Ganni, Venkatarao

    2014-01-01

    The Central Helium Liquefier (CHL) distribution system to the CEBAF and FEL linacs at Jefferson Lab (JLab) experienced a planned warm up during the late summer and fall of 2012 for the first time after its commissioning in 1991. Various maintenance and modifications were performed to support high beam availability to the experimental users, meet 10 CFR 851 requirements for pressure systems, address operational issues, and prepare the cryogenic interfaces for the high-gradient cryomodules needed for the 12 GeV upgrade. Cryogenic maintenance and installation work had to be coordinated with other activities in the linacs and compete for manpower from other department installation activities. With less than a quarter of the gas storage capacity available to handle the boil-off from the more than 40 cryomodules, 35,000 Nm{sup 3} of helium was re-liquefied and shipped to a vendor via a liquid tanker trailer. Nearly 200 u-tubes had to be removed and stored while seals were replaced on related equipment such as vacuum pump outs, bayonet isolation and process valves.

  1. Linac cryogenic distribution system maintenance and upgrades at JLab

    SciTech Connect

    Dixon, K.; Wright, M.; Ganni, V.

    2014-01-29

    The Central Helium Liquefier (CHL) distribution system to the CEBAF and FEL linacs at Jefferson Lab (JLab) experienced a planned warm up during the late summer and fall of 2012 for the first time after its commissioning in 1991. Various maintenance and modifications were performed to support high beam availability to the experimental users, meet 10 CFR 851 requirements for pressure systems, address operational issues, and prepare the cryogenic interfaces for the high-gradient cryomodules needed for the 12 GeV upgrade. Cryogenic maintenance and installation work had to be coordinated with other activities in the linacs and compete for manpower from other department installation activities. With less than a quarter of the gas storage capacity available to handle the boil-off from the more than 40 cryomodules, 35,000 Nm{sup 3} of helium was re-liquefied and shipped to a vendor via a liquid tanker trailer. Nearly 200 u-tubes had to be removed and stored while seals were replaced on related equipment such as vacuum pump outs, bayonet isolation and process valves.

  2. Vacuum simulation and characterization for the Linac4 H- source

    NASA Astrophysics Data System (ADS)

    Pasquino, C.; Chiggiato, P.; Michet, A.; Hansen, J.; Lettry, J.

    2013-02-01

    At CERN, the 160 MeV H- Linac4 will soon replace the 50 MeV proton Linac2. In the H- source two major sources of gas are identified. The first is the pulsed injection at about 0.1 mbar in the plasma chamber. The second is the constant H2 injection up to 10-5 mbar in the LEBT for beam space charge compensation. In addition, the outgassing of materials exposed to vacuum can play an important role in contamination control and global gas balance. To evaluate the time dependent partial pressure profiles in the H- ion source and the RFQ, electrical network - vacuum analogy and test particle Monte Carlo simulation have been used. The simulation outcome indicates that the pressure requirements are in the reach of the proposed vacuum pumping system. Preliminary results show good agreement between the experimental and the simulated pressure profiles; a calibration campaign is in progress to fully benchmark the implemented calculations. Systematic outgassing rate measurements are on-going for critical components in the ion source and RFQ. Amongst them those for the Cu-coated SmCo magnet located in the vacuum system of the biased electron dump electrode, show results lower to stainless steel at room temperature.

  3. CABOTO, a high-gradient linac for hadrontherapy

    PubMed Central

    Verdú-Andrés, Silvia; Amaldi, Ugo; Faus-Golfe, Ángeles

    2013-01-01

    The field of hadrontherapy has grown rapidly in recent years. At present the therapeutic beam is provided by a cyclotron or a synchrotron, but neither cyclotrons nor synchrotrons present the best performances for hadrontherapy. The new generation of accelerators for hadrontherapy should allow fast active energy modulation and have a high repetition rate, so that moving organs can be appropriately treated in a reasonable time. In addition, a reduction of the dimensions and cost of the accelerators for hadrontherapy would make the acquisition and operation of a hadrontherapy facility more affordable, which would translate into great benefits for the potential hadrontherapy patients. The ‘cyclinac’, an accelerator concept that combines a cyclotron with a high-frequency linear accelerator (linac), is a fast-cycling machine specifically conceived to allow for fast active energy modulation. The present paper focuses on CABOTO (CArbon BOoster for Therapy in Oncology), a compact, efficient high-frequency linac that can accelerate C6+ ions and H2 molecules from 150–410 MeV/u in ∼24 m. The paper presents the latest design of CABOTO and discusses its performances. PMID:23824121

  4. RF system considerations for large high-duty-factor linacs

    SciTech Connect

    Lynch, M.T.; Ziomek, C.D.; Tallerico, P.J.; Regan, A.H.; Eaton, L.; Lawrence, G.

    1994-09-01

    RF systems are often a major cost item for linacs, but this is especially true for large high-duty-factor linacs (up to and including CW) such as the Accelerator for Production of Tritium (APT) or the Accelerator for Transmutation of nuclear Waste (ATW). In addition, the high energy and high average beam current of these machines (approximately 1 GeV, 100--200 mA) leads to a need for excellent control of the accelerating fields in order to minimize the possibility of beam loss in the accelerator and the resulting activation. This paper will address the key considerations and limitations in the design of the RF system. These considerations impact the design of both the high power RF components and the RF controls. As might be expected, the two concerns sometimes lead to conflicting design requirements. For example minimum RF operating costs lead to a desire for operation near saturation of the high power RF generators in order to maximize the operating efficiency. Optimal control of the RF fields leads to a desire for maximum overdrive capability in those same generators in order to respond quickly to disturbances of the accelerator fields.

  5. Remarks on the concept of dispersion in a curved linac

    SciTech Connect

    Ostiguy, Jean-Francois; /Fermilab

    2009-01-01

    A next-generation linear collider is expected to span tens of kilometers in length. For various reasons, it may be desirable to house such an accelerator in a tunnel that follows the earth's curvature rather that in a 'laser-straight' tunnel. One side effect of opting for a curved linac is the introduction of vertical dispersion. In recent years, much work has been dedicated to understand and evaluate the impact of the presence of dispersion on emittance preservation. While performing simulations with our in-house code (CHEF) we observed a discrepancy between the dispersion function it produces and that computed using other codes in use within the accelerator community. Understanding the origin and the meaning of this discrepancy required a re-examination of the meaning of the concept of dispersion in the context of a linac. The object of this note is to document our findings. We establish that the default dispersion algorithm used by CHEF corresponds to a different, and ultimately more appropriate, definition of the dispersion in presence of acceleration. Not surprisingly, a consistent definition of dispersion restores agreement between codes.

  6. Alternate Tunings for the Linac Coherent Light Source Photoinjector

    SciTech Connect

    Limborg-Deprey, C.; Emma, P.; /SLAC

    2006-03-17

    The Linac Coherent Light Source (LCLS) is an x-ray free-electron laser (FEL) project based on the SLAC linac. The LCLS Photoinjector beamline has been designed to deliver 10-ps long electron bunches of 1 nC with a normalized projected transverse emittance smaller than 1.2 mm-mrad at 135 MeV. Tolerances and regulation requirements are tight for this tuning. Half of the total emittance at the end of the injector comes from the ''cathode emittance'' which is 0.7 mm-mrad for our nominal 1nC tuning. As the ''cathode emittance'' scales linearly with laser spot radius, the emittance will be dramatically reduced for smaller radius, but this is only possible at lower charge. In particular, for a 0.2 nC charge, we believe we can achieve an emittance closer to 0.4 mm-mrad. This working point will be easier to tune and the beam quality should be much easier to maintain than for the 1 nC case. In the second half of this paper, we discuss optimum laser pulse shapes. We demonstrate that the benefits of the ellipsoidal shapes seem to be important enough so that serious investigations should be carried out in the production of such pulses.

  7. Recirculating Linac Acceleration - End-to-End Simulation

    SciTech Connect

    Alex Bogacz

    2010-03-01

    A conceptual design of a high-pass-number Recirculating Linear Accelerator (RLA) for muons is presented. The scheme involves three superconducting linacs (201 MHz): a single pass linear Pre-accelerator followed by a pair multi-pass (4.5-pass) 'Dogbone' RLAs. Acceleration starts after ionization cooling at 220 MeV/c and proceeds to 12.6 GeV. The Pre-accelerator captures a large muon phase space and accelerates muons to relativistic energies, while adiabatically decreasing the phase-space volume, so that effective acceleration in the RLA is possible. The RLA further compresses and shapes up the longitudinal and transverse phase-spaces, while increasing the energy. Appropriate choice of multi-pass linac optics based on FODO focusing assures large number of passes in the RLA. The proposed 'Dogbone' configuration facilitates simultaneous acceleration of both mu± species through the requirement of mirror symmetric optics of the return 'droplet' arcs. Finally, presented end-to-end simulation validates the efficiency and acceptance of the accelerator system.

  8. Dosimetric Algorithm to Reproduce Isodose Curves Obtained from a LINAC

    PubMed Central

    Estrada Espinosa, Julio Cesar; Martínez Ovalle, Segundo Agustín; Pereira Benavides, Cinthia Kotzian

    2014-01-01

    In this work isodose curves are obtained by the use of a new dosimetric algorithm using numerical data from percentage depth dose (PDD) and the maximum absorbed dose profile, calculated by Monte Carlo in a 18 MV LINAC. The software allows reproducing the absorbed dose percentage in the whole irradiated volume quickly and with a good approximation. To validate results an 18 MV LINAC with a whole geometry and a water phantom were constructed. On this construction, the distinct simulations were processed by the MCNPX code and then obtained the PDD and profiles for the whole depths of the radiation beam. The results data were used by the code to produce the dose percentages in any point of the irradiated volume. The absorbed dose for any voxel's size was also reproduced at any point of the irradiated volume, even when the voxels are considered to be of a pixel's size. The dosimetric algorithm is able to reproduce the absorbed dose induced by a radiation beam over a water phantom, considering PDD and profiles, whose maximum percent value is in the build-up region. Calculation time for the algorithm is only a few seconds, compared with the days taken when it is carried out by Monte Carlo. PMID:25045398

  9. Dosimetric algorithm to reproduce isodose curves obtained from a LINAC.

    PubMed

    Estrada Espinosa, Julio Cesar; Martínez Ovalle, Segundo Agustín; Pereira Benavides, Cinthia Kotzian

    2014-01-01

    In this work isodose curves are obtained by the use of a new dosimetric algorithm using numerical data from percentage depth dose (PDD) and the maximum absorbed dose profile, calculated by Monte Carlo in a 18 MV LINAC. The software allows reproducing the absorbed dose percentage in the whole irradiated volume quickly and with a good approximation. To validate results an 18 MV LINAC with a whole geometry and a water phantom were constructed. On this construction, the distinct simulations were processed by the MCNPX code and then obtained the PDD and profiles for the whole depths of the radiation beam. The results data were used by the code to produce the dose percentages in any point of the irradiated volume. The absorbed dose for any voxel's size was also reproduced at any point of the irradiated volume, even when the voxels are considered to be of a pixel's size. The dosimetric algorithm is able to reproduce the absorbed dose induced by a radiation beam over a water phantom, considering PDD and profiles, whose maximum percent value is in the build-up region. Calculation time for the algorithm is only a few seconds, compared with the days taken when it is carried out by Monte Carlo. PMID:25045398

  10. High-Current Energy-Recovering Electron Linacs

    SciTech Connect

    Nikolitsa Merminga; David Douglas; Geoffrey Krafft

    2003-12-01

    The use of energy recovery provides a potentially powerful new paradigm for generation of the charged particle beams used in synchrotron radiation sources, high-energy electron cooling devices, electron-ion colliders, and other applications in photon science and nuclear and high-energy physics. Energy-recovering electron linear accelerators (called energy-recovering linacs, or ERLs) share many characteristics with ordinary linacs, as their six-dimensional beam phase space is largely determined by electron source properties. However, in common with classic storage rings, ERLs possess a high average-current-carrying capability enabled by the energy recovery process, and thus promise similar efficiencies. The authors discuss the concept of energy recovery and its technical challenges and describe the Jefferson Lab (JLab) Infrared Demonstration Free-Electron Laser (IR Demo FEL), originally driven by a 3548-MeV, 5-mA superconducting radiofrequency (srf) ERL, which provided the most substantial demonstration of energy recovery to date: a beam of 250 kW average power. They present an overview of envisioned ERL applications and a development path to achieving the required performance. They use experimental data obtained at the JLab IR Demo FEL and recent experimental results from CEBAF-ERL GeV-scale, comparatively low-current energy-recovery demonstration at JLab to evaluate the feasibility of the new applications of high-current ERLs, as well as ERLs' limitations and ultimate performance.

  11. Superconducting RF Linac Technology for ERL Light Sources

    SciTech Connect

    Tennant, Chris

    2005-08-01

    Energy Recovering Linacs (ERLs) offer an attractive alternative as drivers for light sources as they combine the desirable characteristics of both storage rings (high efficiency) and linear accelerators (superior beam quality). Using superconducting RF technology allows ERLs to operate more efficiently because of the inherent characteristics of SRF linacs, namely that they are high gradient-low impedance structures and their ability to operate in the long pulse or CW regime. We present an overview of the physics challenges encountered in the design and operation of ERL based light sources with particular emphasis on those issues related to SRF technology. These challenges include maximizing a cavity's Qo to increase cryogenic efficiency, maintaining control of the cavity field in the presence of the highest feasible loaded Q and providing adequate damping of the higher-order modes (HOMs). If not sufficiently damped, dipole HOMs can drive the multipass beam breakup (BBU) instability which ERLs are particularly susceptible to. Another challenge involves efficiently extracting the potentially large amounts of HOM power that are generated when a bunch traverses the SRF cavities and which may extend over a high range of frequencies. We present experimental data from the Jefferson Lab FEL Upgrade, a 10 mA ERL light source presently in operation, aimed at addressing some of these issues. We conclude with an outlook towards the future of ERL based light sources.

  12. Kilovoltage CT using a linac-CT scanner combination.

    PubMed

    Thieke, C; Malsch, U; Schlegel, W; Debus, J; Huber, P; Bendl, R; Thilmann, C

    2006-09-01

    Modern radiotherapy techniques such as intensity modulation are capable of generating complex dose distributions whose high dose areas tightly conform to the tumour target volume, sparing critical organs even when they are located in close proximity. This potential can only be exploited to its full extent when the accumulated dose actually delivered over the complete treatment course is sufficiently close to the dose computed on the initial CT scan used for treatment planning. Exact patient repositioning is mandatory, but also other sources of error, e.g. changes of the patient's anatomy under therapy, should be taken into account. At the German Cancer Research Center, we use a combination of a linear accelerator and a CT scanner installed in one room and sharing the same couch. It allows the quantification and correction of interfractional variations between planning and treatment delivery. In this paper, we describe treatments of prostate, paraspinal and head and neck tumours. All patients were immobilized by customized fixation devices and treated in a stereotactic setup. For each patient, frequent CT scans were taken during the treatment course. Each scan was compared with the original planning CT using manual checks and automatic rigid matching algorithms. Depending on the individual case, the adaptation to variations was carried out offline after several fractions or in real-time between the CT scan and linac irradiation. We discuss the techniques for detecting and correcting interfractional errors and outline the procedural steps of a linac-CT scanner-supported radiation treatment course. PMID:16980687

  13. Modulators for the S-band test linac at DESY

    SciTech Connect

    Bieler, M.; Choroba, S.; Hameister, J.; Lewin, H.

    1995-07-05

    The development of adequate modulators for high peak power klystrons is one of the focus points for linear collider R&D programs. For the DESY/THD S-band linear collider study 150 MW rf-pulse power at 50 Hz repetition rate and 3 {mu}s pulse duration is required [1]. Two different modulator schemes are under investigation. One is the conventional line type pulser, using a pulse forming network and a step up transformer, the other one is a hard tube pulser, using a dc power source at the full klystron voltage and a switch tube. This paper is focused on the modulator development for the S-band Test Linac at DESY. After a short overview over the test linac and a brief description of the 150 MW S-band klystron the circuitry of the line type pulse (LTP) is given. A hard tube pulser (HTP), which switches the high voltage directly from a storage capacitor to the klystron, has been built up at DESY. Circuitry and the results of the commissioning of the switch tube are reported. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  14. Energy-recovery linac project at Cornell University.

    PubMed

    Bilderback, Donald H; Bazarov, I V; Finkelstein, K; Gruner, S M; Padamsee, H S; Sinclair, C K; Shen, Q; Talman, R; Tigner, M; Krafft, G A; Merminga, L

    2003-09-01

    There is considerable interest in using superconducting electron linacs with energy recovery as synchrotron radiation sources. Such energy recovery linacs (ERLs) would open new regimes of X-ray science because they are capable of producing ultra-brilliant X-ray beams [>5 x 10(22) photons s(-1) (0.1% bandwidth)(-1) mm(-2) mrad(-2) at 10 keV], maintaining a very small source size ( approximately 3 micro m r.m.s.) suitable for micro X-ray beams, and making very intense fast ( approximately 100 fs) X-ray pulses. Each of these characteristics would permit the execution of experiments that are not feasible with existing synchrotron sources. Many technical issues must be satisfactorily resolved before the potential of a full-scale ERL can be realised, including the generation of high average current (10 to 100 mA), high-brightness electron beams (0.015 to 0.15 nm rad emittances, respectively); acceleration of these beams to energies of 5-7 GeV without unacceptable emittance degradation; stable and efficient operation of superconducting linear accelerators at very high gradients etc. Cornell University, in collaboration with Jefferson Laboratory, has proposed to resolve these issues by the construction of a 100 MeV, 100 mA prototype ERL. The intention is to then utilize the information that is learned from the prototype to propose the construction of a full-scale ERL light source. PMID:12944617

  15. Thermal analysis for wire scanners in the CSNS Linac

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Fu, Shinian; Xu, Taoguang; Xu, Zhihong; Meng, Ming; Qiu, Ruiyang; Tian, Jianmin; Zeng, Lei; Li, Peng; Li, Fang; Wang, Biao

    2014-10-01

    3 MeV H- beam from the Radio Frequency Quadrupole (RFQ) will be accelerated to 80 MeV in the CSNS (China Spallation Neutron Source) linear accelerator (Linac). The wire scanner is used to measure the transverse beam profile and the emittance, and the carbon or tungsten wire is considered to use. Thermal analysis of the wire scanners in the Linac is presented in this paper. The maximum temperature (Tm) of the wire decreases as the beam energy increases, and we also calculate the influence of all possible parameters on Tm. Tm of carbon wire is significantly lower than tungsten wire if both the beam parameters and wire geometric parameters are set to the same, which can be attributed to its higher heat capacity and radiant emissivity. In addition, we present the results of sublimation rate of the wire, which show that tungsten wire has a much lower evaporation rate than carbon wire in the same temperature, which can be attributed to the different vapor pressures of the two materials. To limit the thermionic emission, the maximum beam frequency approximately has an exponential relationship with beam rms size at a certain beam pulse width.

  16. Linac head scatter factor for asymmetric radiation field

    NASA Astrophysics Data System (ADS)

    Soubra, Mazen Ahmed

    1997-11-01

    The head scatter factor, Sh is an important dosimetric quantity used in radiation therapy dose calculation. It is empirically determined and its field size dependence reflects changes in photon scatter from components in the linac treatment head. In this work a detailed study of the physical factors influencing the determination of Sh was performed with particular attention given to asymmetric field geometries. Ionization measurements for 6 and 18 MV photon beams were made to examine the factors which determine Sh. These include: phantom size and material, collimator backscatter, non-lateral electronic equilibrium (LEE) conditions, electron contamination, collimator-exchange, photon energy, flattening filter and off-axis distance (OAD). Results indicated that LEE is not required for Sh measurements if electron contamination is minimized. Brass caps or polystyrene miniphantoms can both be used in Sh measurements provided the phantom thickness is large enough to stop contaminant electrons. Backscatter radiation effects into the monitor chamber were found to be negligible for the Siemens linac. It was found that the presence and shape of the flattening filter had a significant effect on the empirically determined value of Sh was also shown to be a function of OAD, particularly for small fields. For fields larger than 12×12 cm2/ Sh was independent of OAD. A flattening filter mass model was introduced to explain qualitatively the above results. A detailed Monte Carlo simulation of the Siemens KD2 linac head in 6 MV mode was performed to investigate the sources of head scatter which contribute to the measured Sh. The simulated head components include the flattening filter, the electron beam stopper, the primary collimator, the photon monitor chamber and the secondary collimators. The simulations showed that the scatter from the head of the Siemens linac is a complex function of the head components. On the central axis the flattening filter played the dominant role in

  17. Application of positron annihilation in materials science

    SciTech Connect

    Siegel, R.W.; Fluss, M.J.; Smedskjaer, L.C.

    1984-05-01

    Owing to the ability of the positron to annihilate from a variety of defect-trapped states, positron annihilation spectroscopy (PAS) has been applied increasingly to the characterization and study of defects in materials in recent years. In metals particularly, it has been demonstrated that PAS can yield defect-specific information which, by itself or in conjunction with more traditional experimental techniques, has already made a significant impact upon the determination of atomic-defect properties and the monitoring and characterization of vacancy-like microstructure development, as occurs during post-irradiation annealing. The applications of PAS are now actively expanding to the study of more complex defect-related phenomena in irradiated or deformed metals and alloys, phase transformations and structural disorder, surfaces and near-surface defect characterization. A number of these applications in materials science are reviewed and discussed with respect to profitable future directions.

  18. Cold Positrons from Decaying Dark Matter

    SciTech Connect

    Boubekeur, Lotfi; Dodelson, Scott; Vives, Oscar

    2012-11-01

    Many models of dark matter contain more than one new particle beyond those in the Standard Model. Often heavier particles decay into the lightest dark matter particle as the Universe evolves. Here we explore the possibilities that arise if one of the products in a (Heavy Particle) $\\rightarrow$ (Dark Matter) decay is a positron, and the lifetime is shorter than the age of the Universe. The positrons cool down by scattering off the cosmic microwave background and eventually annihilate when they fall into Galactic potential wells. The resulting 511 keV flux not only places constraints on this class of models but might even be consistent with that observed by the INTEGRAL satellite.

  19. Do positrons measure atomic and molecular diameters?

    NASA Astrophysics Data System (ADS)

    Franz, Jan; Fedus, Kamil; Karwasz, Grzegorz P.

    2016-07-01

    We report on density functional calculations (DFT) of elastic integral scattering cross-sections for positron collisions with argon, krypton, nitrogen and methane. The long-range asymptotic polarization potential is described using higher-order terms going much beyond an induced dipole potential (- α / r 4) while the short-range interaction is modeled by two different forms of electron - positron correlation potential (Boroński-Nieminen and Quantum Monte Carlo potentials). The results of both approaches agree quite well with the recent theoretical and measured values. Based on the present and previous theoretical and experimental data we discuss some systematics observed in integral scattering cross-sections below the positronium formation threshold. In particular we point out on the correlation between the values of scattering cross-sections and atomic dimensions.

  20. Positronium formation in positron-helium scattering

    SciTech Connect

    Khan, P.; Ghosh, A.S.

    1983-10-01

    The positronium-formation cross sections in positron-helium scattering have been calculated with the use of a distorted-wave polarized-orbital method from the threshold to 100 eV. The results with and without the matrix elements involving the distorted target wave functions are found to differ appreciably. The results of the first Born approximation are not expected to be correct even at the incident-positron energy 100 eV. The measured values at 20 eV are found to be less than (1/2) of the present predicted values. The sharp rise of the formation cross section within the ore-gap region as observed by Charlton et al. has also been noticed by us. The minimum in the differential cross section has been found at all energies as in the case of hydrogen atom.

  1. Positron annihilation gamma rays from novae

    NASA Technical Reports Server (NTRS)

    Leising, Mark D.; Clayton, Donald D.

    1987-01-01

    The potential for observing annihilation gamma rays from novae is investigated. These gamma rays, a unique signature of the thermonuclear runaway models of novae, would result from the annihilation of positrons emitted by beta(+)-unstable nuclei produced near the peak of the runaway and carried by rapid convection to the surface of the nova envelope. Simple models, which are extensions of detailed published models, of the expansion of the nova atmospheres are evolved. These models serve as input into investigations of the fate of nearby Galactic fast novae could yield detectable fluxes of electron-positron annihilation gamma rays produced by the decay of N-13 and F-18. Although nuclear gamma-ray lines are produced by other nuclei, it is unlikely that the fluxes at typical nova distances would be detectable to present and near-future instruments.

  2. Positron annihilation radiation from solar flares

    NASA Technical Reports Server (NTRS)

    Share, G. H.; Chupp, E. L.; Forrest, D. J.; Rieger, E.

    1983-01-01

    Positron-annihilation radiation has been observed from the June 21, 1980 and June 3, 1982 flares by the gamma-ray spectrometer on the Solar Maximum Mission satellite. The observed 0.511-MeV line fluences from the flares were 14.6 + or - 3.3 gamma/sq cm and 103 + or - 8 gamma/sq cm, respectively. Measurement of the line width establishes an upper limit to the temperature in the annihilation region of 3 x 10 to the 6th K. The time dependence of the 0.511-MeV line during the 1980 flare is consistent with the calculations of Ramaty et al. (1983) for positrons created in the decay of radioactive nuclei. The time dependence of the 0.511-MeV line for the 1982 flare is more complex and requires more detailed study.

  3. Positron scattering and annihilation from hydrogenlike ions

    SciTech Connect

    Novikov, S.A.; Bromley, M.W.J.; Mitroy, J.

    2004-05-01

    The Kohn variational method is used with a configuration-interaction-type wave function to determine the J=0 and J=1 phase shifts and annihilation parameter Z{sub eff} for positron-hydrogenic ion scattering. The phase shifts are within 1-2% of the best previous calculations. The values of Z{sub eff} are small and do not exceed unity for any of the momenta considered. At thermal energies Z{sub eff} is minute with a value of order 10{sup -50} occurring for He{sup +} at k=0.05a{sub 0}{sup -1}. In addition to the variational calculations, analytic expressions for the phase shift and annihilation parameters within the Coulomb wave Born approximation are derived and used to help elucidate the dynamics of positron collisions with positive ions.

  4. Microemulsion systems studied by positron annihilation techniques

    SciTech Connect

    Boussaha, A.; Djermouni, B.; Fucugauchi, L.A.; Ache, H.J.

    1980-07-02

    The formation of thermalized positronium atoms is greatly reduced if increasing amounts of water become solubilized in reversed micelles formed by sodium bis(2-ethylhexyl) sulfosuccinate in apolar solvents. Similar observations have been made if the surfactant is Triton X-100. The application of the positron annihilation technique to the study of microemulsions consisting of potassium oleate-alcohol-oil-water mixtures indicates, consistent with previous results, that microemulsion formation requires a certain water/oil ratio if the oil is a long-chain aliphatic hydrocarbon such as hexadecane. This ratio is 0.4 in the case of a 1-pentanol- and 0.2 for a 1-hexanol-containing mixture. This minimum water content is strongly reduced if the oil is an aromatic hydrocarbon. The positron annihilation data also sensitively reflect structural rearrangements in these solutions occurring upon further addition of water, such as the transition of spherical aggregates to a disk-like lamellae structure.

  5. Positron spectroscopy of 2D materials using an advanced high intensity positron beam

    NASA Astrophysics Data System (ADS)

    McDonald, A.; Chirayath, V.; Lim, Z.; Gladen, R.; Chrysler, M.; Fairchild, A.; Koymen, A.; Weiss, A.

    An advanced high intensity variable energy positron beam(~1eV to 20keV) has been designed, tested and utilized for the first coincidence Doppler broadening (CDB) measurements on 6-8 layers graphene on polycrystalline Cu sample. The system is capable of simultaneous Positron annihilation induced Auger electron Spectroscopy (PAES) and CDB measurements giving it unparalleled sensitivity to chemical structure at external surfaces, interfaces and internal pore surfaces. The system has a 3m flight path up to a micro channel plate (MCP) for the Auger electrons emitted from the sample. This gives a superior energy resolution for PAES. A solid rare gas(Neon) moderator was used for the generation of the monoenergetic positron beam. The positrons were successfully transported to the sample chamber using axial magnetic field generated with a series of Helmholtz coils. We will discuss the PAES and coincidence Doppler broadening measurements on graphene -Cu sample and present an analysis of the gamma spectra which indicates that a fraction of the positrons implanted at energies 7-60eV can become trapped at the graphene/metal interface. This work was supported by NSF Grant No. DMR 1508719 and DMR 1338130.

  6. Positron studies of defected metals, metallic surfaces

    SciTech Connect

    Bansil, A.

    1991-01-01

    Specific problems proposed under this project included the treatment of electronic structure and momentum density in various disordered and defected systems. Since 1987, when the new high-temperature superconductors were discovered, the project focused extensively on questions concerning the electronic structure and Fermiology of high-[Tc] superconductors, in particular, (i) momentum density and positron experiments, (ii) angle-resolved photoemission intensities, (iii) effects of disorder and substitutions in the high-[Tc]'s.

  7. Orbiting transmission source for positron tomography

    SciTech Connect

    Huesman, R.H.; Derenzo, S.E.; Cahoon, J.L.; Geyer, A.B.; Moses, W.W.; Uber, D.C.; Vuletich, T.; Budinger, T.F.

    1988-02-01

    Accidental suppression and effective data rates have been measured for the orbiting transmission source as implemented in the Donner 600-Crystal Positron Tomograph. A mechanical description of the orbiting source and a description of the electronics used to discard scattered and accidental events is included. Since accidental coincidences were the rate-limiting factor in transmission data acquisition, the new method allows us to acquire sufficient transmission data in a shorter time with a more active transmission source.

  8. Cosmic-ray Positrons from Millisecond Pulsars

    NASA Astrophysics Data System (ADS)

    Venter, C.; Kopp, A.; Harding, A. K.; Gonthier, P. L.; Büsching, I.

    2015-07-01

    Observations by the Fermi Large Area Telescope of γ-ray millisecond pulsar (MSP) light curves imply copious pair production in their magnetospheres, and not exclusively in those of younger pulsars. Such pair cascades may be a primary source of Galactic electrons and positrons, contributing to the observed enhancement in positron flux above ∼10 GeV. Fermi has also uncovered many new MSPs, impacting Galactic stellar population models. We investigate the contribution of Galactic MSPs to the flux of terrestrial cosmic-ray electrons and positrons. Our population synthesis code predicts the source properties of present-day MSPs. We simulate their pair spectra invoking an offset-dipole magnetic field. We also consider positrons and electrons that have been further accelerated to energies of several TeV by strong intrabinary shocks in black widow (BW) and redback (RB) systems. Since MSPs are not surrounded by pulsar wind nebulae or supernova shells, we assume that the pairs freely escape and undergo losses only in the intergalactic medium. We compute the transported pair spectra at Earth, following their diffusion and energy loss through the Galaxy. The predicted particle flux increases for non-zero offsets of the magnetic polar caps. Pair cascades from the magnetospheres of MSPs are only modest contributors around a few tens of GeV to the lepton fluxes measured by the Alpha Magnetic Spectrometer, PAMELA, and Fermi, after which this component cuts off. The contribution by BWs and RBs may, however, reach levels of a few tens of percent at tens of TeV, depending on model parameters.

  9. Positron annihilation in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    1990-01-01

    Emission features appear at energies of 350 to 450 keV in the spectra of a number of gamma ray burst sources. These features were interpreted as electron-positron annihilation lines, redshifted by the gravitational field near the surface of a neutron star. Evidence that gamma ray bursts originate at neutron stars with magnetic field strengths of approx. 10(exp 12) Gauss came from recent observations of cyclotron scattering harmonics in the spectra of two bursts. Positrons could be produced in gamma ray burst sources either by photon-photon pair production or by one-photon pair production in a strong magnetic field. The annihilation of positrons is affected by the presence of a strong neutron star magnetic field in several ways. The relaxation of transverse momentum conservation causes an intrinsic broadening of the two-photon annihilation line and there is a decrease in the annihilation cross section below the free-space value. An additional channel for one-photon annihilation also becomes possible in high magnetic fields. The physics of pair production and annihilation near strongly magnetized neutron stars will be reviewed. Results from a self-consistent model for non-thermal synchrotron radiation and pair annihilation are beginning to identify the conditions required to produce observable annihilation features from strongly magnetized plasmas.

  10. Development of a medium-energy superconducting heavy-ion linac.

    SciTech Connect

    Ostroumov, P. N.; Physics

    2002-03-01

    The Rare Isotope Accelerator (RIA) facility project includes a cw 1.4 GeV driver linac and a 100 MV postaccelerator both based on superconducting (SC) cavities operating at frequencies from 48 to 805 MHz. In these linacs more than 99% of the total voltage is provided by SC cavities. An initial acceleration is provided by room temperature radio frequency quadrupoles. The driver linac is designed for acceleration of any ion species, from protons up to 900 MeV to uranium up to 400 MeV/u. The novel feature of the driver linac is an acceleration of multiple charge-state heavy-ion beams in order to achieve 400 kW beam power. This paper presents design features of a medium-energy SC heavy-ion linac taking the RIA driver linac as an example. The dynamics of single and multiple charge-state beams are detailed, including the effects of possible errors in rf field parameters and misalignments of transverse focusing elements. The important design considerations of such linac are presented. Several new conceptual solutions in beam dynamics in SC accelerating structures for heavy-ion applications are discussed.

  11. Beam Dynamics Aspects of High Current Beams in a Superconducting Proton Linac

    NASA Astrophysics Data System (ADS)

    Bellomo, Giovanni; Pagani, Carlo; Pierini, Paolo

    1997-05-01

    High current CW proton linac accelerators have been recently proposed for nuclear waste transmutation and concurrent energy production. In most of the designs the high energy part (100 MeV up to 1-2 GeV) of the linac employs low frequency superconducting structures (352-700 MHz). Here we present beam dynamics issues for the high current (10-50 mA) beams in the superconducting section of such an accelerator, based on 352 MHz β-graded, LEP style cavities, as proposed at Linac 96(C. Pagani, G. Bellomo, P. Pierini, ``Linac96/Proceedings/Monday/MOP23/Paper.html>A High Current Proton Linac with 352 MHz SC Cavities'', Proceedings of the XVIII Int. Linear Acc. Conf., eds. C. Hill, M. Vretenar, CERN 96-07, 15 November 1996). In particular, smooth beam propagation along the linac has been reached with decreasing phase advances along the linac, and the design has been updated to match the beam dynamics results. Mismatching oscillations are discussed, as they are considered to cause beam halo and, consequently, beam losses.

  12. Linac with integrated power source based on radio frequency energy compression

    NASA Astrophysics Data System (ADS)

    Smirnov, A. V.; Smirnov, V. N.

    1995-03-01

    The basic feasibility of a proposal to simplify the conventional low energy rf electron linear accelerator (linac), is considered. The design suggested foresees replacement of the traditional high power systems of external rf generator and modulator by a more passive switched energy storage system. The proposed conception of a compact linac is based on known rf energy compression techniques and an efficient self-excited oscillation in a special accelerating/oscillating linac structure. The principal relations, performance estimations, and one-dimensional time-dependent simulation results for such a linac are presented. The possibility of self-excited oscillation by an unbunched low voltage beam in a waveguide linac section is proved and investigated experimentally. The common features and differences compared with a conventional backward-wave tube are analyzed. An application of this effect is proposed for impedance and group velocity measurements in slow-wave structures. Since the rf energy commutation may be one or two orders faster than the electric high voltage energy commutation (conventional modulator), combining the structure proposed and rf energy compression system can give high levels of the average beam power (10-100 kW). The linac facility would have considerably reduced weight and sizes (more than 2.5 times) as compared to similar industrial linacs. The power supply required is in 40-120 kV range dc source, and an estimated overall wall plug efficiency is a few percent.

  13. An Overview of the MaRIE X-FEL and Electron Radiography LINAC RF Systems

    SciTech Connect

    Bradley, Joseph Thomas III; Rees, Daniel Earl; Scheinker, Alexander; Sheffield, Richard L.

    2015-05-04

    The purpose of the Matter-Radiation Interactions in Extremes (MaRIE) facility at Los Alamos National Laboratory is to investigate the performance limits of materials in extreme environments. The MaRIE facility will utilize a 12 GeV linac to drive an X-ray Free-Electron Laser (FEL). Most of the same linac will also be used to perform electron radiography. The main linac is driven by two shorter linacs; one short linac optimized for X-FEL pulses and one for electron radiography. The RF systems have historically been the one of the largest single component costs of a linac. We will describe the details of the different types of RF systems required by each part of the linacs. Starting with the High Power RF system, we will present our methodology for the choice of RF system peak power and pulselength with respect to klystron parameters, modulator parameters, performance requirements and relative costs. We will also present an overview of the Low Level RF systems that are proposed for MaRIE and briefly describe their use with some proposed control schemes.

  14. Reduction of Positron Range Effects by the Application of a Magnetic Field: for Use with Positron Emission Tomography

    NASA Astrophysics Data System (ADS)

    Raylman, Raymond Robert

    The process of positron emission tomography has become a valuable medical research tool. This procedure involves the administration of a radiopharmaceutical labelled with a positron-emitting isotope to a living organism. Upon the emission and subsequent annihilation of a positron, the gamma rays produced are detected to create an image of metabolic activity within the subject. Many factors such as Compton scattering and photoelectric absorption of the gamma rays tend to limit the quality of these images. Another important limitation is the non-negligible distance the positron travels prior to annihilation. This phenomenon leads to the misplacement of data in the final image. A method for reducing this effect utilizing a magnetic field has been tested and evaluated. The application of a magnetic field constrains the positrons to travel in helical paths instead of their relatively straight courses. Thus, the effective distance the positrons travel from their point of emission is reduced. Results indicate that this technique is successful in reducing the blurring caused in PET images by positron range. The results also indicate that the amount of resolution improvement depends upon the choice of positron emitter and scanner resolution. Reduction of this blurring helps to produce clearer PET images which can allow for more precise localization of tumors, in addition to better measurement of metabolic rate constants. The use of a magnetic field to reduce the range of positrons will lead to more useful images produced by positron emission tomography.

  15. PULSED-FOCUSING RECIRCULATING LINACS FOR MUON ACCELERATION

    SciTech Connect

    Johnson, Rolland PAUL

    2014-12-31

    Since the muon has a short lifetime, fast acceleration is essential for high-energy applications such as muon colliders, Higgs factories, or neutrino factories. The best one can do is to make a linear accelerator with the highest possible accelerating gradient to make the accelerating time as short as possible. However, the cost of such a single linear accelerator is prohibitively large due to expensive power sources, cavities, tunnels, and related infrastructure. As was demonstrated in the Thomas Jefferson Accelerator Facility (Jefferson Lab) Continuous Electron Beam Accelerator Facility (CEBAF), an elegant solution to reduce cost is to use magnetic return arcs to recirculate the beam through the accelerating RF cavities many times, where they gain energy on each pass. In such a Recirculating Linear Accelerator (RLA), the magnetic focusing strength diminishes as the beam energy increases in a conventional linac that has constant strength quadrupoles. After some number of passes the focusing strength is insufficient to keep the beam from going unstable and being lost. In this project, the use of fast pulsed quadrupoles in the linac sections was considered for stronger focusing as a function of time to allow more successive passes of a muon beam in a recirculating linear accelerator. In one simulation, it was shown that the number of passes could be increased from 8 to 12 using pulsed magnet designs that have been developed and tested. This could reduce the cost of linac sections of a muon RLA by 8/12, where more improvement is still possible. The expense of a greater number of passes and corresponding number of return arcs was also addressed in this project by exploring the use of ramped or FFAG-style magnets in the return arcs. A better solution, invented in this project, is to use combined-function dipole-quadrupole magnets to simultaneously transport two beams of different energies through one magnet string to reduce costs of return arcs by almost a factor of

  16. Beam loss studies in high-intensity heavy-ion linacs

    NASA Astrophysics Data System (ADS)

    Ostroumov, P. N.; Aseev, V. N.; Mustapha, B.

    2004-09-01

    The proposed Rare Isotope Accelerator (RIA) Facility, an innovative exotic-beam facility for the production of high-quality beams of short-lived isotopes, consists of a fully superconducting 1.4GV driver linac and a 140MV postaccelerator. To produce sufficient intensities of secondary beams the driver linac will provide 400kW primary beams of any ion from hydrogen to uranium. Because of the high intensity of the primary beams the beam losses must be minimized to avoid radioactivation of the accelerator equipment. To keep the power deposited by the particles lost on the accelerator structures below 1 W/m, the relative beam losses per unit length should be less than 10-5, especially along the high-energy section of the linac. A new beam dynamics simulation code TRACK has been developed and used for beam loss studies in the RIA driver linac. In the TRACK code, ions are tracked through the three-dimensional electromagnetic fields of every element of the linac starting from the electron cyclotron resonance (ECR) ion source to the production target. The simulation starts with a multicomponent dc ion beam extracted from the ECR. The space charge forces are included in the simulations. They are especially important in the front end of the driver linac. Beam losses are studied by tracking a large number of particles (up to 106) through the whole linac considering all sources of error such us element misalignments, rf field errors, and stripper thickness fluctuations. For each configuration of the linac, multiple sets of error values have been randomly generated and used in the calculations. The results are then combined to calculate important beam parameters, estimate beam losses, and characterize the corresponding linac configuration. To track a large number of particles for a comprehensive number of error sets (up to 500), the code TRACK was parallelized and run on the Jazz computer cluster at ANL.

  17. Positron Production at JLab Simulated Using Geant4

    SciTech Connect

    Kossler, W. J.; Long, S. S.

    2009-09-02

    The results of a Geant4 Monte-Carlo study of the production of slow positrons using a 140 MeV electron beam which might be available at Jefferson Lab are presented. Positrons are produced by pair production for the gamma-rays produced by bremsstrahlung on the target which is also the stopping medium for the positrons. Positrons which diffuse to the surface of the stopping medium are assumed to be ejected due to a negative work function. Here the target and moderator are combined into one piece. For an osmium target/moderator 3 cm long with transverse dimensions of 1 cm by 1 mm, we obtain a slow positron yield of about 8.5centre dot10{sup 10}/(scentre dotmA) If these positrons were remoderated and re-emitted with a 23% probability we would obtain 2centre dot10{sup 10}/(scentre dotmA) in a micro-beam.

  18. Positron density enhancements recorded within a thunderstorm by ADELE

    NASA Astrophysics Data System (ADS)

    Dwyer, J. R.; Smith, D. M.; Hazelton, B. J.; Grefenstette, B.; Kelley, N. A.; Lowell, A. W.; Schaal, M.; Rassoul, H.

    2015-12-01

    We report the observation of two unusual positron density enhancements made inside an active thunderstorm by the Airborne Detector for Energetic Lightning Emissions (ADELE) onboard a Gulfstream V aircraft in August 2009. ADELE recorded two count rate enhancements of 511 keV annihilation gamma rays, 35 seconds apart, that lasted approximately 0.2 seconds each. The enhancements were about a factor of 12 above background and had energy spectra consistent with clouds of positrons, approximately 1 km across, briefly surrounding the aircraft. A flat-plate antenna on the underside of the aircraft also recorded electrical activity during the positron enhancements. It is not clear how the positron clouds were created within the thunderstorm or whether the presence of the aircraft played a role in their production. In this presentation, we will show the ADELE data along with model fits of the positron spectra. We shall also discuss possible sources of the positron excesses.

  19. [Basic principles of 18F-fluorodeoxyglucose positron emission tomography].

    PubMed

    Standke, R

    2002-01-01

    Positron emission tomography uses photons to receive regional information about dynamic, physiologic, and biochemical processes in the living body. A positron decay is measured indirectly by the simultaneous registration of both gamma rays created by the annihilation. The event is counted, if two directly opposite located detectors register gamma rays in coincidence. Unfortunately the detectors of a positron emission tomography system do not register only true coincident events. There are also scattered and random coincidences. Different types of positron tomographs are presented and scintillation crystals, which are in use for positron emission tomography are discussed. The 2D- and 3D-acquisition methods are described as well as preprocessing methods, such as correction for attenuation, scatter and dead time. For quantification the relative parameter standard uptake value (SUV) is explained. Finally hybrid systems, such as combined positron emission tomography/computed tomography scanners and the use of computed tomography data for attenuation correction are introduced. PMID:12506765

  20. STATUS OF R AND D ENERGY RECOVERY LINAC AT BROOKHAVEN NATIONAL LABORATORY.

    SciTech Connect

    LITVINENKO,V.; BEN-ZVI, I.; ALDUINO, J.M.; BARTON, D.S.; BEAVIS, D.; BLASKIEWICZ, M.; ET AL.

    2007-06-25

    In this paper we present status and plans for the 20-MeV R&D energy recovery linac (ERL), which is under construction at Collider Accelerator Department at BNL. The facility is based on high current (up to 0.5 A of average current) super-conducting 2.5 MeV RF gun, single-mode super-conducting 5-cell RF linac and about 20-m long return loop with very flexible lattice. The R&D ERL, which is planned for commissioning in early 2009, aims to address many outstanding questions relevant for high current, high brightness energy recovery linacs.