Complete snake and rotator schemes for spin polarization in proton rings and large electron rings

International Nuclear Information System (INIS)

Steffen, K.

1983-11-01

In order to maintain spin polarization in proton rings and large electron rings, some generalized Siberian Snake scheme may be required to make the spin tune almost independent of energy and thus avoid depolarizing resonances. The practical problem of finding such schemes that, at reasonable technical effort, can be made to work over large energy ranges has been addressed before and is here revisited in a broadened view and with added new suggestions. As a result, possibly optimum schemes for electron rings (LEP) and proton rings are described. In the proposed LEP scheme, spin rotation is devised such that, at the interaction points, the spin direction is longitudinal as required for experiments. (orig.)

Status report on the Los Alamos proton storage ring

International Nuclear Information System (INIS)

Colton, E.; Neuffer, D.; Thiessen, H.A.

1988-01-01

The proton storage ring currently operates at an average current of 30 μA corresponding to 1.25 /times/ 10 13 protons per pulse (ppp) at a repetition rate of 15 Hz. The design operating current for the machine is 100 μA. We are limited to running at the reduced yield because of beam losses during the accumulation period. These losses are understood and arise mainly from emittance growths during the injection and multiple scattering in the stripping foil during the storage. During beam studies we have succeeded in accumulating in excess of 3.7 /times/ 10 13 ppp. We have also observed a coherent transverse instability at high charge levels. The signature for the instability is rapid coherent growth of the transverse beam size followed by a loss of beam in the machine. The threshold for the instability depends most strongly upon rf voltage and beam size. 3 refs., 1 fig., 1 tab

Proton storage ring: man/machine interface

International Nuclear Information System (INIS)

Lander, R.F.; Clout, P.N.

1985-01-01

The human interface of the Proton Storage Ring Control System at Los Alamos is described in some detail, together with the software environment in which operator interaction programs are written. Some examples of operator interaction programs are given

Status of PSR [Proton Storage Ring

International Nuclear Information System (INIS)

Macek, R.J.

1989-01-01

The Los Alamos Proton Storage Ring (PSR) now operates with 35μA at 20-Hz pulse repetition rate. Beam availability during 1988 suffered because of a number of problems with hardware reliability and from narrow operating margins for beam spill in the extraction line. A strong effort is underway to improve reliability with an eventual goal of obtaining beam availability in excess of 75%. Beam losses and the resulting component activation have limited operating currents to their present values. In detailed studies of the problem, loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two-step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. It is now apparent that the key to reducing losses is in reducing the number of foil traversals. A program of upgrades to reduce losses and improve the operating current is being planned. 8 refs., 16 figs

Test of internal halo targets in the HERA proton ring

International Nuclear Information System (INIS)

Hast, C.; Hofmann, W.; Khan, S.; Knoepfle, K.T.; Reber, M.; Rieling, J.; Spahn, M.; Spengler, J.; Lohse, T.; Pugatch, V.

1994-07-01

Internal wire targets in the halo of stored proton beams provide a line source of proton-nucleus interactions for highest-rate fixed target experiments. We have studied such internal halo targets at the 820 GeV proton ring of the HERA ep collider. The tests showed that most of the protons in the beam halo - which would otherwise hit the collimators - can be brought to interaction in a relatively thin target wire at distances of 7 to 8 beam widths from the center of the beam. At less than 10% of the HERA total design current, and less than 20% of the current per bunch, interaction rates up to 8 MHz were observed, corresponding to more than 2 interactions per bunch crossing. The halo targets were used in parallel to the HERA luminosity operation; no significant disturbances of the HERA ep experiments, of the machine stability or beam quality were observed. We present data on the steady-state and transient behaviour of interaction rates and discuss the interpretation in terms of a simple beam dynamics model. Issues of short-, medium- and long-term rate fluctuations and of rate stabilization by feedback are addressed. (orig.)

Test of internal halo targets in the HERA proton ring

International Nuclear Information System (INIS)

Hast, C.; Hofmann, W.; Khan, S.; Knoepfle, K.T.; Reber, M.; Rieling, J.; Spahn, M.; Spengler, J.; Lohse, T.; Pugatch, V.

1995-01-01

Internal wire targets in the halo of stored proton beams provide a line source of proton-nucleus interactions for highest-rate fixed target experiments. We have studied such internal halo targets at the 820 GeV proton ring of the HERA ep collider. The tests showed that most of the protons in the beam halo - which would otherwise hit the collimators - can be brought to interaction in a relatively thin target wire at distances of 7 to 8 beam widths from the center of the beam. At less than 10% of the HERA total design current, and less than 20% of the current per bunch, interaction rates up to 8 MHz were observed, corresponding to more than 2 interactions per bunch crossing. The halo targets were used in parallel to the HERA luminosity operation; no significant disturbances of the HERA ep experiments, of the machine stability or beam quality were observed. We present data on the steady-state and transient behaviour of interaction rates and discuss the interpretation in terms of a simple beam dynamics model. Issues of short-, medium- and long-term rate fluctuations and of rate stabilization by feedback are addressed. ((orig.))

Proton storage ring summer workshop

International Nuclear Information System (INIS)

Lawrence, G.P.; Cooper, R.K.

1977-10-01

During the week of August 16, 1976 a Workshop was held at the Los Alamos Scientific Laboratory (LASL) on the Proton Storage Ring (PSR) for the Weapons Neutron Research Facility (WNRF). Written contributions were solicited from each of the participants in the Workshop, and the contributions that were received are presented. The papers do not represent polished or necessarily complete work, but rather represent ''first cuts'' at their respective areas. Topics covered include: (1) background information on the storage ring; (2) WNRF design; (3) rf transient during filling; (4) rf capture; (5) beam bunch compression; (6) transverse space charge limits; (7) transverse resistive instability in the PSR; (8) longitudinal resistive instability; (9) synchrotron frequency splitting; (10) E Quintus Unum--off resonance; (11) first harmonic bunching in the storage ring; (12) kicker considerations; (13) beam extraction; (14) ferrite kicker magnets; and (15) E Quintus Unum: a possible ejection scheme

Coulomb collisions of ring current particles: Indirect source of heat for the ionosphere

Science.gov (United States)

Cole, K. D.

1975-01-01

The additional energy requirements of the topside ionosphere during a magnetic storm are less than one quarter of the ring current energy. This energy is supplied largely by Coulomb collisions of ring current protons of energy less than about 20 keV with background thermal electrons which conduct the heat to the ionosphere. Past criticisms are discussed of this mechanism for the supply of energy to the SAR-arc and neighboring regions of the ionosphere.

Current-current interaction picture for proton-proton scattering

International Nuclear Information System (INIS)

Clarke, D.J.; Lo, S.Y.

1979-01-01

The authors propose that color current - color current interaction is reponsible for small angle elastic proton proton scattering at asymptotic energy. Excellent fits are obtained for all data above 12 GeV/c which covers twelve orders of magnitude

Proton accumulator ring injection studies

International Nuclear Information System (INIS)

Cooper, R.K.; Neil, V.K.

1977-01-01

Protons may be created in an accelerator or storage ring by stripping electrons from neutral hydrogen atoms that have been injected into the machine. Because Liouville's theorem is violated by this type of injection, particles may be continually injected into a region of phase space that is already populated, and the density in that region increases with time. A computational investigation was made of the evolution of the distribution of particles in longitudinal phase space during such an injection process for a storage ring operating below the transition energy. In one calculation, an rf cavity is present in the ring and particles are injected into the stable phase region once each revolution. The purpose of this calculation is to determine the rf voltage necessary to overcome the longitudinal self-forces and contain the particles within the region of stable phase. In a second calculation, the rf is turned off, so that there is spreading in azimuth of the injected particles (i.e., de-bunching). The de-bunching occurs because of the initial energy spread and the action of the self-forces. One purpose of the calculation is to determine the total energy spread after a given number of revolutions. Another purpose is to elucidate the effect of finite resistance in the vacuum tank walls. For sufficiently high current, the finite resistance can cause bunching of a beam that is initially uniform in azimuth. Therefore it might be expected that the finite resistance would inhibit or prevent de-bunching once the number of particles injected reaches some threshold, and that this threshold would depend upon the energy spread in the beam

Pulsed Power Applications in High Intensity Proton Rings

CERN Document Server

Zhang, Wu; Ducimetière, Laurent; Fowler, Tony; Kawakubo, Tadamichi; Mertens, Volker; Sandberg, Jon; Shirakabe, Yoshihisa

2005-01-01

The pulsed power technology has been applied in particle accelerators and storage rings for over four decades. It is most commonly used in injection, extraction, beam manipulation, source, and focusing systems. These systems belong to the class of repetitive pulsed power. In this presentation, we review and discuss the history, present status, and future challenge of pulsed power applications in high intensity proton accelerators and storage rings.

MeV proton flux predictions near Saturn's D ring.

Science.gov (United States)

Kollmann, P; Roussos, E; Kotova, A; Cooper, J F; Mitchell, D G; Krupp, N; Paranicas, C

2015-10-01

Radiation belts of MeV protons have been observed just outward of Saturn's main rings. During the final stages of the mission, the Cassini spacecraft will pass through the gap between the main rings and the planet. Based on how the known radiation belts of Saturn are formed, it is expected that MeV protons will be present in this gap and also bounce through the tenuous D ring right outside the gap. At least one model has suggested that the intensity of MeV protons near the planet could be much larger than in the known belts. We model this inner radiation belt using a technique developed earlier to understand Saturn's known radiation belts. We find that the inner belt is very different from the outer belts in the sense that its intensity is limited by the densities of the D ring and Saturn's upper atmosphere, not by radial diffusion and satellite absorption. The atmospheric density is relatively well constrained by EUV occultations. Based on that we predict an intensity in the gap region that is well below that of the known belts. It is more difficult to do the same for the region magnetically connected to the D ring since its density is poorly constrained. We find that the intensity in this region can be comparable to the known belts. Such intensities pose no hazard to the mission since Cassini would only experience these fluxes on timescales of minutes but might affect scientific measurements by decreasing the signal-to-contamination ratio of instruments.

Storage ring proton EDM experiment

CERN Multimedia

CERN. Geneva

2015-01-01

sensitivity of 10^-29 e-cm.  The strength of the method originates from the fact that there are high intensity polarized proton beams available and the fact that the so-called geometric phase systematic error background cancels with clock-wise and counter-clock-wise storage possible in electric rings. The ultimate sensitivity of the method is 10^-30 e-cm. At this level it will either detect a non-zero EDM or it will eliminate electro-weak baryogenesis.

The proton storage ring: Problems and solutions

International Nuclear Information System (INIS)

Macek, R.J.

1988-01-01

The Los Alamos Proton Storage Ring (PSR) now operates with 35μA at 20-Hz pulse repetition rate. Beam availability during 1988 suffered because of a number of problems with hardware reliability and from narrow operating margins for beam spill in the extraction line. A strong effort is underway to improve reliability with an eventual goal of obtaining beam availability in excess of 75%. Beam losses and the resulting component activation have limited operating currents to their present values. In detailed studies of the problem, loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two-step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. It is now apparent that the key to reducing losses is in reducing the number of foil traversals. A program of upgrades to reduce losses and improve the operating current is being planned. 8 refs., 17 figs., 2 tabs

The proton storage ring: Problems and solutions

International Nuclear Information System (INIS)

Macek, R.J.

1989-01-01

The Los Alamos Proton Storage Ring (PSR) now operates with 35μA at 20-Hz pulse repetition rate. Beam availability during 1988 suffered because of a number of problems with hardware reliability and from narrow operating margins for beam spill in the extraction line. A strong effort is underway to improve reliability with an eventual goal of obtaining beam availability in excess of 75%. Beam losses and the resulting component activation have limited operating currents to their present values. In detail studies of the problem, loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two-step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. It is now apparent that the key to reducing losses is in reducing the number of foil traversals. A program of upgrades to reduce losses and improve the operating current is being planned. 8 refs., 17 figs., 2 tabs

Scaling in inelastic proton-proton interactions at storage ring energies of 23-63 GeV

International Nuclear Information System (INIS)

Thome, W.

1980-02-01

In this paper inelastic proton-proton interactions are studied with low transversal momenta ( approx. equal to 350 MeV/c) of the final state hadrons. The reaction products from p-p collisions have been detected for the first time visually, using two large streamer chambers which enclose one interaction region of the CERN storage rings almost completely. (orig./HSI) [de

Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities

Directory of Open Access Journals (Sweden)

K.-H. Glassmeier

1999-03-01

Full Text Available Giant pulsations are nearly monochromatic ULF-pulsations of the Earth's magnetic field with periods of about 100 s and amplitudes of up to 40 nT. For one such event ground-magnetic observations as well as simultaneous GEOS-2 magnetic and electric field data and proton flux measurements made in the geostationary orbit have been analysed. The observations of the electromagnetic field indicate the excitation of an odd-mode type fundamental field line oscillation. A clear correlation between variations of the proton flux in the energy range 30-90 keV with the giant pulsation event observed at the ground is found. Furthermore, the proton phase space density exhibits a bump-on-the-tail signature at about 60 keV. Assuming a drift-bounce resonance instability as a possible generation mechanism, the azimuthal wave number of the pulsation wave field may be determined using a generalized resonance condition. The value determined in this way,  m = - 21 ± 4, is in accord with the value m = - 27 ± 6 determined from ground-magnetic measurements. A more detailed examination of the observed ring current plasma distribution function f shows that odd-mode type eigenoscillations are expected for the case ∂f / ∂W > 0, much as observed. This result is different from previous theoretical studies as we not only consider local gradients of the distribution function in real space, but also in velocity space. It is therefore concluded that the observed giant pulsation is the result of a drift-bounce resonance instability of the ring current plasma coupling to an odd-mode fundamental standing wave. The generation of the bump-on-the-tail distribution causing ∂f / ∂W > 0 can be explained due to velocity dispersion of protons injected into the ring current. Both this velocity dispersion and the necessary substorm activity causing the injection of protons into the nightside magnetosphere are observed.Key words. Magnetospheric physics (energetic particles , trapped

Design for a second-generation proton storage ring at LAMPF

International Nuclear Information System (INIS)

Colton, E.P.

1988-01-01

A conceptual design is presented for a second-generation proton storage ring complex at LAMPF. The facility would consist of two stacked racetrack-shaped machines. These machines would deliver a 1.2-mA beam of 1.6-GeV protons at 48 Hz. The pulse length would be 1.75 μsec which represents a time compression of 570. 1 ref., 8 figs., 1 tab

Radiation environment of proton accelerators and storage rings

Energy Technology Data Exchange (ETDEWEB)

Stevenson, G R

1976-03-08

These lecture notes survey the physical processes that give rise to the stray-radiation environment of proton synchrotrons and storage rings, with emphasis on their importance for radiation protection. The origins of the prompt radiation field (which disappears when the accelerator is switched off) are described in some detail: proton-nucleus interactions, extranuclear cascades, muon generation and transport. The effects of induced radioactivity in the accelerator structure and surroundings, notably in iron, concrete, air, and water, are discussed, and methods for monitoring hadrons in the radiation environment outside the accelerator are listed. Seventy-six references to the literature are included.

Radial transport of storm time ring current ions

Science.gov (United States)

Lui, A. T. Y.

1993-01-01

Radial transport of energetic ions for the development of the main phase of geomagnetic storms is investigated with data from the medium energy particle analyzer (MEPA) on the Charge Composition Explorer spacecraft, which monitored protons, helium ions, and the carbon-nitrogen-oxygen group, which is mostly dominated by oxygen ions. From a study of four geomagnetic storms, we show that the flux increase of these ions in the inner ring current region can be accounted for by an inward displacement of the ring current population by 0.5 to 3.5 R(E). There is a general trend that a larger inward displacement occurs at higher L shells than at lower ones. These results are in agreement with previous findings. The radially injected population consists of the prestorm population modified by substorm injections which occur on a much shorter time scale than that for a storm main phase. It is also found that the inward displacement is relatively independent of ion mass and energy, suggesting that the radial transport of these energetic ions is effected primarily by convective motion from a large electric field or by diffusion resulting from magnetic field fluctuations.

IKOR - An isochronous pulse compressor ring for proton beams

International Nuclear Information System (INIS)

Schaffer, G.

1981-06-01

This report contains the results of a study carried out for an isochronous compressor ring IKOR which compresses the 500 μs linac macropulses into pulses of 0.68 μs length. Its basic component is a ring magnet with alternating gradient and separated functions. Due to the isochronous operation, an rf system can be avoided which otherwise would be necessary in order to maintain a void in the circulating beam for the purpose of ejection. Injection is performed by charge exchange. The H - beam of the accelerator is first converted into a H 0 beam by stripping off one electron by a high gradient magnet placed in the transfer channel. Subsequently, the beam is converted into a proton beam by removing the remaining electron through a stripping foil in the ring. IKOR will be filled in 658 turns. Immediately after filling, the beam is ejected in a single turn via a kicker and a septum magnet and is transported to the spallation target. Because of the high intensity of 2.7 x 10 14 protons per pulse and, secondly, due to the high repetition rate of 100 Hz, beam dynamics and radiation protection aspects dominate the design and are, for this reason, treated in detail. (orig.)

Spectrum Analyzer Application for the Proton Synchrotron Wall Current Monitors

CERN Document Server

Limpens, Rik

The Proton Synchrotron (PS) is a key component in CERN's accelerator complex, where it usually accelerates either protons or heavy ions. The new acquisition system for the PS ring wall current monitors has been installed to be able to perform higher frequency measurements of a beam bunch. This is an important improvement, since the oscillating signals are related to losses of a beam bunch. The main goal of this project is to develop a LabVIEW application running on a Real-Time target to perform continuous and triggered spectral acquisition of a PS beam bunch and to provide a data visualization and analysis tool for the operators and users of the machine.

Concerning the generation of geomagnetic giant pulsations by drift-bounce resonance ring current instabilities

Directory of Open Access Journals (Sweden)

K.-H. Glassmeier

Full Text Available Giant pulsations are nearly monochromatic ULF-pulsations of the Earth's magnetic field with periods of about 100 s and amplitudes of up to 40 nT. For one such event ground-magnetic observations as well as simultaneous GEOS-2 magnetic and electric field data and proton flux measurements made in the geostationary orbit have been analysed. The observations of the electromagnetic field indicate the excitation of an odd-mode type fundamental field line oscillation. A clear correlation between variations of the proton flux in the energy range 30-90 keV with the giant pulsation event observed at the ground is found. Furthermore, the proton phase space density exhibits a bump-on-the-tail signature at about 60 keV. Assuming a drift-bounce resonance instability as a possible generation mechanism, the azimuthal wave number of the pulsation wave field may be determined using a generalized resonance condition. The value determined in this way, 
m = - 21 ± 4, is in accord with the value m = - 27 ± 6 determined from ground-magnetic measurements. A more detailed examination of the observed ring current plasma distribution function f shows that odd-mode type eigenoscillations are expected for the case ∂f / ∂W > 0, much as observed. This result is different from previous theoretical studies as we not only consider local gradients of the distribution function in real space, but also in velocity space. It is therefore concluded that the observed giant pulsation is the result of a drift-bounce resonance instability of the ring current plasma coupling to an odd-mode fundamental standing wave. The generation of the bump-on-the-tail distribution causing ∂f / ∂W > 0 can be explained due to velocity dispersion of protons injected into the ring current. Both this velocity dispersion and the necessary substorm activity causing the injection of protons into the nightside magnetosphere are observed

CONSIDERATIONS ABOUT PROTON - NEUTRON INTERACTIONS IN THE INTERSECTING STORAGE RINGS

CERN Document Server

Bartl, W; Steuer, M; Hubner, K

1969-01-01

The pos'sibility of proton-neutron scattering experiments at the CERN Intersecting Storage Rings is studied. The use of proton-deuteron collisions to measure the reaction p+d •*• p*pv+n,witheitherp.orn,asspectator nucléon is discussed. An analysing magnet around the deuteron beamline allows to detect both nucléons of the deuteron up to the zero-momentum-transfer" région. Accélération and storage of deuteron beams is considered.

Electron cloud development in the Proton Storage Ring and in the Spallation Neutron Source

International Nuclear Information System (INIS)

Pivi, M.T.F.; Furman, M.A.

2002-01-01

We have applied our simulation code ''POSINST'' to evaluate the contribution to the growth rate of the electron-cloud instability in proton storage rings. Recent simulation results for the main features of the electron cloud in the storage ring of the Spallation Neutron Source(SNS) at Oak Ridge, and updated results for the Proton Storage Ring (PSR) at Los Alamos are presented in this paper. A key ingredient in our model is a detailed description of the secondary emitted-electron energy spectrum. A refined model for the secondary emission process including the so-called true secondary, rediffused and backscattered electrons has recently been included in the electron-cloud code

Charge Exchange Contribution to the Decay of the Ring Current, Measured by Energetic Neutral Atoms (ENAs)

Science.gov (United States)

Jorgensen, A. M.; Henderson, M. G.; Roelof, E. C.; Reeves, G. D.; Spence, H. E.

2001-01-01

In this paper we calculate the contribution of charge exchange to the decay of the ring current. Past works have suggested that charge exchange of ring current protons is primarily responsible for the decay of the ring current during the late recovery phase, but there is still much debate about the fast decay of the early recovery phase. We use energetic neutral atom (ENA) measurements from Polar to calculate the total ENA energy escape. To get the total ENA escape we apply a forward modeling technique, and to estimate the total ring current energy escape we use the Dessler-Parker-Sckopke relationship. We find that during the late recovery phase of the March 10, 1998 storm ENAs with energies greater than 17.5 keV can account for 75% of the estimated energy loss from the ring current. During the fast recovery the measured ENAs can only account for a small portion of the total energy loss. We also find that the lifetime of the trapped ions is significantly shorter during the fast recovery phase than during the late recovery phase, suggesting that different processes are operating during the two phases.

The radiation environment of proton accelerators and storage rings

International Nuclear Information System (INIS)

Stevenson, G.R.

1976-01-01

These lecture notes survey the physical processes that give rise to the stray-radiation environment of proton synchrotrons and storage rings, with emphasis on their importance for radiation protection. The origins of the prompt radiation field (which disappears when the accelerator is switched off) are described in some detail: proton-nucleus interactions, extranuclear cascades, muon generation and transport. The effects of induced radioactivity in the accelerator structure and surroundings, notably in iron, concrete, air, and water, are discussed and methods for monitoring hadrons in the radiation environment outside the accelerator are listed. Seventy-six references to the literature are included. (Author)

Nonlinear interaction of energetic ring current protons with magnetospheric hydromagnetic waves

International Nuclear Information System (INIS)

Chan, A.A.; Chen, L.; White, R.B.

1989-01-01

In order to study nonlinear wave-particle interactions in the Earth's magnetosphere we have derived Hamiltonian equations for the gyrophase-averaged nonrelativistic motion of charged particles in a perturbed dipole magnetic field. We assume low frequency (less than the proton gyrofrequency) fully electromagnetic perturbations, and we retain finite Larmor radius effects. Analytic and numerical results for the stochastic threshold of energetic protons (approx-gt 100 keV) in compressional geomagnetic pulsations in the Pc 5 range of frequencies 150--600 seconds are presented. These protons undergo a drift-bounce resonance with the Pc 5 waves which breaks the second (longitudinal) and third (flux) adiabatic invariants, while the first invariant (the magnetic moment) and the proton energy are approximately conserved. The proton motion in the observed spectrum of waves is found to be strongly diffusive, due to the overlap of neighboring primary resonances. copyright American Geophysical Union 1989

Nonlinear interaction of energetic ring current protons with magnetospheric hydromagnetic waves

International Nuclear Information System (INIS)

Chan, A.A.; Chen, Liu; White, R.B.

1989-09-01

In order to study nonlinear wave-particle interactions in the earth's magnetosphere we have derived Hamiltonian equations for the gyrophase-averaged nonrealistic motion of charged particles in a perturbed dipole magnetic field. We assume low frequency (less than the proton gyrofrequency) fully electromagnetic perturbations, and we retain finite Larmor radius effects. Analytic and numerical results for the stochastic threshold of energetic protons (approx gt 100 keV) in compressional geomagnetic pulsations in the Pc 5 range of frequencies (150--600 seconds) are presented. These protons undergo a drift-bounce resonance with the Pc 5 waves which breaks the second (longitudinal) and third (flux) adiabatic invariants, while the first invariant (the magnetic moment) and the proton energy are approximately conserved. The proton motion in the observed spectrum of waves is found to be strongly diffusive, due to the overlap of neighboring primary resonances. 17 refs., 2 figs

On propagating direction of ring current proton ULF waves observed by ATS 6 at 6.6 R/sub e/

International Nuclear Information System (INIS)

Su, S.; Konradi, A.; Fritz, T.A.

1977-01-01

From June 11 to September 16, 1974, the NOAA low-energy proton detector on board the ATS 6 satellite observed 71 cases of ultralow-frequency oscillations of proton flux intensities. The oscillation periods varied from 40 s to 6 min, and the events were observed most frequently during moderate geomagnetic conditions. The flux oscillations occurred at various local times, yet almost two thirds of the events were detected in the near-dusk region of the magentosphere. For a majority of the events in this set a substantial phase shift in flux oscillation was detected between different energy channels and/or between two oppositely oriented detector telescopes. The phase shift is mainly due to the finite gyroradius effect of the protons gyrating in the geomagnetic field. By examining this finite gyroradius effect on the perturbed particle distribution function associated with the wave in a nonuniform magnetic field we are able to determine the propagation direction of the wave from particle observations made by a single spacecraft. Although the type of wave and its excitation mechanism can only be conjectured at the present time, it is concluded that the wave propagates in the westward direction with a phase velocity of about 13 km/s. Furthermore, it also has a very small phase velocity approx.0.15 km/s propagating toward the earth. If the wave had been traveling 1 hour or so before it was observed near the dusk magnetosphere, it might have originated in the dark magnetosphere in associating with some changes in geophysical conditions. The statistical correlation between the times of the observed wave events and the onsets of the auroral magnetic bays indicates that although they seldom occurred simultaneously, 80% of the waves were observed within 1 hour of the bay onset. Therefore it is concluded that the condition of the magnetosphere after a substorm is favorable for the occurrence of the ring current proton ultralow-frequency waves

A storage ring experiment to detect a proton electric dipole moment

Energy Technology Data Exchange (ETDEWEB)

Anastassopoulos, V. [Department of Physics, University of Patras, 26500 Rio-Patras, Greece; Andrianov, S. [Faculty of Applied Mathematics and Control Processes, Saint-Petersburg State University, Saint-Petersburg, Russia; Baartman, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia V6T2A3, Canada; Baessler, S. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904, USA; Bai, M. [Institut für Kernphysik and JARA-Fame, Forschungszentrum Jülich, 52425 Jülich, Germany; Benante, J. [Brookhaven National Laboratory, Upton, New York 11973, USA; Berz, M. [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA; Blaskiewicz, M. [Brookhaven National Laboratory, Upton, New York 11973, USA; Bowcock, T. [Department of Physics, University of Liverpool, Liverpool, United Kingdom; Brown, K. [Brookhaven National Laboratory, Upton, New York 11973, USA; Casey, B. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA; Conte, M. [Physics Department and INFN Section of Genoa, 16146 Genoa, Italy; Crnkovic, J. D. [Brookhaven National Laboratory, Upton, New York 11973, USA; D’Imperio, N. [Brookhaven National Laboratory, Upton, New York 11973, USA; Fanourakis, G. [Institute of Nuclear and Particle Physics NCSR Demokritos, GR-15310 Aghia Paraskevi Athens, Greece; Fedotov, A. [Brookhaven National Laboratory, Upton, New York 11973, USA; Fierlinger, P. [Technical University München, Physikdepartment and Excellence-Cluster “Universe,” Garching, Germany; Fischer, W. [Brookhaven National Laboratory, Upton, New York 11973, USA; Gaisser, M. O. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Giomataris, Y. [CEA/Saclay, DAPNIA, 91191 Gif-sur-Yvette Cedex, France; Grosse-Perdekamp, M. [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA; Guidoboni, G. [University of Ferrara, INFN of Ferrara, Ferrara, Italy; Hacıömeroğlu, S. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Hoffstaetter, G. [Laboratory for Elementary-Particle Physics, Cornell University, Ithaca, New York 14853, USA; Huang, H. [Brookhaven National Laboratory, Upton, New York 11973, USA; Incagli, M. [Physics Department, University and INFN Pisa, Pisa, Italy; Ivanov, A. [Faculty of Applied Mathematics and Control Processes, Saint-Petersburg State University, Saint-Petersburg, Russia; Kawall, D. [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA; Kim, Y. I. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; King, B. [Department of Physics, University of Liverpool, Liverpool, United Kingdom; Koop, I. A. [Budker Institute of Nuclear Physics, 630090 Novosibirsk, Russia; Lazarus, D. M. [Brookhaven National Laboratory, Upton, New York 11973, USA; Lebedev, V. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA; Lee, M. J. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Lee, S. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Lee, Y. H. [Korea Research Institute of Standards and Science, Daejeon 34141, South Korea; Lehrach, A. [Institut für Kernphysik and JARA-Fame, Forschungszentrum Jülich, 52425 Jülich, Germany; RWTH Aachen University and JARA-Fame, III. Physikalisches Institut B, Physikzentrum, 52056 Aachen, Germany; Lenisa, P. [University of Ferrara, INFN of Ferrara, Ferrara, Italy; Levi Sandri, P. [Laboratori Nazionali di Frascati, INFN, I-00044 Frascati, Rome, Italy; Luccio, A. U. [Brookhaven National Laboratory, Upton, New York 11973, USA; Lyapin, A. [Royal Holloway, University of London, Egham, Surrey, United Kingdom; MacKay, W. [Brookhaven National Laboratory, Upton, New York 11973, USA; Maier, R. [Institut für Kernphysik and JARA-Fame, Forschungszentrum Jülich, 52425 Jülich, Germany; Makino, K. [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA; Malitsky, N. [Brookhaven National Laboratory, Upton, New York 11973, USA; Marciano, W. J. [Brookhaven National Laboratory, Upton, New York 11973, USA; Meng, W. [Brookhaven National Laboratory, Upton, New York 11973, USA; Meot, F. [Brookhaven National Laboratory, Upton, New York 11973, USA; Metodiev, E. M. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Harvard College, Harvard University, Cambridge, Massachusetts 02138, USA; Miceli, L. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Moricciani, D. [Dipartimento di Fisica dell’Univ. di Roma “Tor Vergata” and INFN Sezione di Roma Tor Vergata, Rome, Italy; Morse, W. M. [Brookhaven National Laboratory, Upton, New York 11973, USA; Nagaitsev, S. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA; Nayak, S. K. [Brookhaven National Laboratory, Upton, New York 11973, USA; Orlov, Y. F. [Laboratory for Elementary-Particle Physics, Cornell University, Ithaca, New York 14853, USA; Ozben, C. S. [Istanbul Technical University, Istanbul 34469, Turkey; Park, S. T. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Pesce, A. [University of Ferrara, INFN of Ferrara, Ferrara, Italy; Petrakou, E. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Pile, P. [Brookhaven National Laboratory, Upton, New York 11973, USA; Podobedov, B. [Brookhaven National Laboratory, Upton, New York 11973, USA; Polychronakos, V. [Brookhaven National Laboratory, Upton, New York 11973, USA; Pretz, J. [RWTH Aachen University and JARA-Fame, III. Physikalisches Institut B, Physikzentrum, 52056 Aachen, Germany; Ptitsyn, V. [Brookhaven National Laboratory, Upton, New York 11973, USA; Ramberg, E. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA; Raparia, D. [Brookhaven National Laboratory, Upton, New York 11973, USA; Rathmann, F. [Institut für Kernphysik and JARA-Fame, Forschungszentrum Jülich, 52425 Jülich, Germany; Rescia, S. [Brookhaven National Laboratory, Upton, New York 11973, USA; Roser, T. [Brookhaven National Laboratory, Upton, New York 11973, USA; Kamal Sayed, H. [Brookhaven National Laboratory, Upton, New York 11973, USA; Semertzidis, Y. K. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea; Senichev, Y. [Institut für Kernphysik and JARA-Fame, Forschungszentrum Jülich, 52425 Jülich, Germany; Sidorin, A. [Joint Institute for Nuclear Research, Dubna, Moscow region, Russia; Silenko, A. [Joint Institute for Nuclear Research, Dubna, Moscow region, Russia; Research Institute for Nuclear Problems of Belarusian State University, Minsk, Belarus; Simos, N. [Brookhaven National Laboratory, Upton, New York 11973, USA; Stahl, A. [RWTH Aachen University and JARA-Fame, III. Physikalisches Institut B, Physikzentrum, 52056 Aachen, Germany; Stephenson, E. J. [Indiana University Center for Spacetime Symmetries, Bloomington, Indiana 47405, USA; Ströher, H. [Institut für Kernphysik and JARA-Fame, Forschungszentrum Jülich, 52425 Jülich, Germany; Syphers, M. J. [Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA; Department of Physics, Northern Illinois University, DeKalb, Illinois 60115, USA; Talman, J. [Brookhaven National Laboratory, Upton, New York 11973, USA; Talman, R. M. [Laboratory for Elementary-Particle Physics, Cornell University, Ithaca, New York 14853, USA; Tishchenko, V. [Brookhaven National Laboratory, Upton, New York 11973, USA; Touramanis, C. [Department of Physics, University of Liverpool, Liverpool, United Kingdom; Tsoupas, N. [Brookhaven National Laboratory, Upton, New York 11973, USA; Venanzoni, G. [Laboratori Nazionali di Frascati, INFN, I-00044 Frascati, Rome, Italy; Vetter, K. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA; Vlassis, S. [Department of Physics, University of Patras, 26500 Rio-Patras, Greece; Won, E. [Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34141, South Korea; Physics Department, Korea University, Seoul 02841, South Korea; Zavattini, G. [University of Ferrara, INFN of Ferrara, Ferrara, Italy; Zelenski, A. [Brookhaven National Laboratory, Upton, New York 11973, USA; Zioutas, K. [Department of Physics, University of Patras, 26500 Rio-Patras, Greece

2016-11-01

A new experiment is described to detect a permanent electric dipole moment of the proton with a sensitivity of $10^{-29}e\\cdot$cm by using polarized "magic" momentum $0.7$~GeV/c protons in an all-electric storage ring. Systematic errors relevant to the experiment are discussed and techniques to address them are presented. The measurement is sensitive to new physics beyond the Standard Model at the scale of 3000~TeV.

A storage ring experiment to detect a proton electric dipole moment.

Science.gov (United States)

Anastassopoulos, V; Andrianov, S; Baartman, R; Baessler, S; Bai, M; Benante, J; Berz, M; Blaskiewicz, M; Bowcock, T; Brown, K; Casey, B; Conte, M; Crnkovic, J D; D'Imperio, N; Fanourakis, G; Fedotov, A; Fierlinger, P; Fischer, W; Gaisser, M O; Giomataris, Y; Grosse-Perdekamp, M; Guidoboni, G; Hacıömeroğlu, S; Hoffstaetter, G; Huang, H; Incagli, M; Ivanov, A; Kawall, D; Kim, Y I; King, B; Koop, I A; Lazarus, D M; Lebedev, V; Lee, M J; Lee, S; Lee, Y H; Lehrach, A; Lenisa, P; Levi Sandri, P; Luccio, A U; Lyapin, A; MacKay, W; Maier, R; Makino, K; Malitsky, N; Marciano, W J; Meng, W; Meot, F; Metodiev, E M; Miceli, L; Moricciani, D; Morse, W M; Nagaitsev, S; Nayak, S K; Orlov, Y F; Ozben, C S; Park, S T; Pesce, A; Petrakou, E; Pile, P; Podobedov, B; Polychronakos, V; Pretz, J; Ptitsyn, V; Ramberg, E; Raparia, D; Rathmann, F; Rescia, S; Roser, T; Kamal Sayed, H; Semertzidis, Y K; Senichev, Y; Sidorin, A; Silenko, A; Simos, N; Stahl, A; Stephenson, E J; Ströher, H; Syphers, M J; Talman, J; Talman, R M; Tishchenko, V; Touramanis, C; Tsoupas, N; Venanzoni, G; Vetter, K; Vlassis, S; Won, E; Zavattini, G; Zelenski, A; Zioutas, K

2016-11-01

A new experiment is described to detect a permanent electric dipole moment of the proton with a sensitivity of 10 -29 e ⋅ cm by using polarized "magic" momentum 0.7 GeV/c protons in an all-electric storage ring. Systematic errors relevant to the experiment are discussed and techniques to address them are presented. The measurement is sensitive to new physics beyond the standard model at the scale of 3000 TeV.

Conceptual Design Report. Antiproton - Proton Collider Upgrade 20 GeV Rings. Technical Components and Civil Construction May, 1988

Energy Technology Data Exchange (ETDEWEB)

None

1988-05-01

This report contains a description of the design and cost estimate of two new 20 GeV rings which will be required to support the upgrade of the Fermilab Collider with a luminosity goal of 5x10 ³¹ cm^-2s^-1. The new rings include an antiproton post-accumulator, denoted the Antiproton Super Booster (ASB), and a proton post-booster, denoted the Proton Super Booster (PSB). The siting of the rings is shown in Figure I-1. Both rings are capable of operation at 20 GeV, eliminating the need for ever again injecting beam into the Main Ring below transition, and significantly enhancing Main Ring performance. The Antiproton Super Booster is designed to accept and accumulate up to 4x10¹² antiprotons from the existing Antiproton Accumulator, and deliver them to the Main Ring at 20 GeV for acceleration and injection into the Collider. It is also designed to accept diluted antiprotons from the Main Ring at 20 GeV for recooling. The PSB accepts 8.9 GeV protons from the existing Booster and accelerates them to 20 GeV for injection into the Main Ring. The PSB is designed to operate at 5 Hz. The siting shown in Figure I-1 has the attractive feature that it removes all Main Ring injection hardware from the AO straight section, opening the possibility of installing a third proton-antiproton interaction region in the Tevatron Collider.

Electron cloud instabilities in the Proton Storage Ring and Spallation Neutron Source

Directory of Open Access Journals (Sweden)

M. Blaskiewicz

2003-01-01

Full Text Available Electron cloud instabilities in the Los Alamos Proton Storage Ring and those foreseen for the Oak Ridge Spallation Neutron Source are examined theoretically, numerically, and experimentally.

Theory and design aspects of the 1 GeV proton compressor ring for pulsed beams of spallation neutrons and muons

International Nuclear Information System (INIS)

Rees, G.H.

1988-05-01

In the present paper, an outline design is presented for a 50 Hz, 1 GeV proton compressor ring of Japanese Hadron Project. The design aims are to provide two pulses of 1 GeV protons with an average current of 200 μA, one pulse with the time duration of 20 ns and the other of 100 - 200 ns. Very important aspects of magnet lattice, injection scheme, bunch compression process, beam instabilities are discussed. (author)

Ion transport and loss in the earth's quiet ring current. I - Data and standard model

Science.gov (United States)

Sheldon, R. B.; Hamilton, D. C.

1993-01-01

A study of the transport and loss of ions in the earth's quiet time ring current, in which the standard radial diffusion model developed for the high-energy radiation belt particles is compared with the measurements of the lower-energy ring current ions, is presented. The data set provides ionic composition information in an energy range that includes the bulk of the ring current energy density, 1-300 keV/e. Protons are found to dominate the quiet time energy density at all altitudes, peaking near L of about 4 at 60 keV/cu cm, with much smaller contributions from O(+) (1-10 percent), He(+) (1-5 percent), and He(2+) (less than 1 percent). A minimization procedure is used to fit the amplitudes of the standard electric radial diffusion coefficient, yielding 5.8 x 10 exp -11 R(E-squared)/s. Fluctuation ionospheric electric fields are suggested as the source of the additional diffusion detected.

Ring-like spatial distribution of laser accelerated protons in the ultra-high-contrast TNSA-regime

Science.gov (United States)

Becker, G. A.; Tietze, S.; Keppler, S.; Reislöhner, J.; Bin, J. H.; Bock, L.; Brack, F.-E.; Hein, J.; Hellwing, M.; Hilz, P.; Hornung, M.; Kessler, A.; Kraft, S. D.; Kuschel, S.; Liebetrau, H.; Ma, W.; Polz, J.; Schlenvoigt, H.-P.; Schorcht, F.; Schwab, M. B.; Seidel, A.; Zeil, K.; Schramm, U.; Zepf, M.; Schreiber, J.; Rykovanov, S.; Kaluza, M. C.

2018-05-01

The spatial distribution of protons accelerated from submicron-thick plastic foil targets using multi-terawatt, frequency-doubled laser pulses with ultra-high temporal contrast has been investigated experimentally. A very stable, ring-like beam profile of the accelerated protons, oriented around the target’s normal direction has been observed. The ring’s opening angle has been found to decrease with increasing foil thicknesses. Two-dimensional particle-in-cell simulations reproduce our results indicating that the ring is formed during the expansion of the proton density distribution into the vacuum as described by the mechanism of target-normal sheath acceleration. Here—in addition to the longitudinal electric fields responsible for the forward acceleration of the protons—a lateral charge separation leads to transverse field components accelerating the protons in the lateral direction.

Topological ring currents in the "empty" ring of benzo-annelated perylenes.

Science.gov (United States)

Dickens, Timothy K; Mallion, Roger B

2011-01-27

Cyclic conjugation in benzo-annelated perylenes is examined by means of the topological π-electron ring currents calculated for each of their constituent rings, in a study that is an exact analogy of a recent investigation by Gutman et al. based on energy-effect values for the corresponding rings in each of these structures. "Classical" approaches, such as Kekulé structures, Clar "sextet" formulas, and circuits of conjugation, predict that the central ring in perylene is "empty" and thus contributes negligibly to cyclic conjugation. However, conclusions from the present calculations of topological ring currents agree remarkably with those arising from the earlier study involving energy-effect values in that, contrary to what would be predicted from the classical approaches, rings annelated in an angular fashion relative to the central ring of these perylene structures materially increase the extent of that ring's involvement in cyclic conjugation. It is suggested that such close quantitative agreement between the predictions of these two superficially very different indices (energy effect and topological ring current) might be due to the fact that, ultimately, both depend, albeit in ostensibly quite different ways, only on an adjacency matrix that contains information about the carbon-carbon connectivity of the conjugated system in question.

Electron - proton colliders

International Nuclear Information System (INIS)

Wiik, B.H.

1985-01-01

Electron-proton storage rings allow us to study the interaction between the two basic constituents of matter, electrons and quarks at very short distances. Such machines were first discussed in connection with the ISR but the idea was abandoned because of the anticipated low counting rate. The interest in electron-proton storage rings was rekindeled by the discovery of large pointlike cross sections in lepton-hardon interactions and several/sup 2-15/ projects have been discussed during the past decade. However, despite a glorious past, which includes the discovery of quarks and neutral currents, and a multitude of proposals no electron-proton storage ring has ever been built. What we might learn by studying electron-proton collisions at high energies is discussed. After some brief comments on present proposals the proposed DESY ep project HERA is described as an example of how to realize such a machine

Preliminary results of proton ring current observations in time of magnetic perturbations with the 'Molniya-1' satellite

International Nuclear Information System (INIS)

Grechin, A.N.; Kovrygina, L.M.; Kovtyukh, A.S.

1975-01-01

The experimental results of observation on the injection of the annular current protons (30< Esub(r)<380 KeV) into the radiation band during the storm on October 28, 1973 and three storms on January 1, 1974, July 12 and 21, 1974, with the maximum values of Dsup(st) of 65, 30, and 20γ, respectively, are described. During the main phases of the storms the assymetry of the annular current of protons relative to the mid-day-mid-night meridian was observed. The injection of the particles was being accompanied by variation of the shape of the spectrum on the internal edge of the annular current. The possible effect of the ion-cyclotron instability on the formation of the initial edge of the annular current has been analyzed. Immediately after the main phases of the storms on July 12 and 21, 1974, a gap in the spectum within the pre-mid-night sector, with the energies amounting to several dozens of KeV was observed. The formation of this gap may be explained by the development of the instability which results in the pinch-angular diffusion of protons and their decay in the region of plasmapause

The role of ring current O+ in the formation of stable auroral red arcs

International Nuclear Information System (INIS)

Kozyra, J.U.; Cravens, T.E.; Nagy, A.F.; Shelley, E.G.; Comfort, R.H.; Brace, L.H.

1987-01-01

Coulomb collisions between ring current protons and thermal electrons were first proposed by Cole (1965) as the energy source for stable auroral red (SAR) arcs. Recent observations have shown that the ring current and magnetospheric plasma contain significant amounts of heavy ions (Johnson et al., 1977; Young et al., 1977; Geiss et al., 1978; and others). In fact, the ring current is often dominated by heavy ions at those energies (E ≤ 17 keV) important for Coulomb collisions on SAR arc field lines (Kozyra et al., 1986a). Observations (during four SAR arcs in 1981) of thermal and energetic ion populations by the Dynamics Explorer 1 satellite in the magnetospheric energy source region and nearly simultaneous Langmuir probe measurements of enhanced electron temperatures by Dynamics Explorer 2 within the SAR arc at F region heights have allowed the authors to examine the role of heavy ions in the formation of SAR arcs. They find that (1) sufficient energy is transferred to the electron gas at high altitudes via Coulomb collisions between the observed ring current ions and thermal electrons to support the enhanced (SAR arc) F region electron temperatures measured on these field lines, (2) the latitudinal variation in the electron heating rates calculated using observed ion populations is consistent with the observed variation in electron temperature across the SAR arc, and (3) in all cases, ring current O + is the major source of energy for the SAR arcs. This implies a relationship between the heavy ion content of the magnetospheric plasma and the occurrence frequency and intensity of SAR arcs

Studies on beam extraction from the 1 GeV proton accumulator ring

International Nuclear Information System (INIS)

Goyal, Pradeep Kumar; Sharma, Amalendu; Kumar, Vinit; Ghodke, A.D.

2015-01-01

For the proposed Indian Spallation Neutron Source (ISNS), a 1 GeV proton Accumulator Ring (AR) is presently being designed at RRCAT. Two optics configurations of AR, namely FODO and Hybrid lattices are under consideration. Each lattice configuration has four superperiods. In this paper, preliminary studies on beam extraction from AR are presented for both the optics configurations. The extraction system will be accommodated in one of the long dispersion free straight sections. Bunch length of the proton beam in AR is 700 ns, and the revolution time of the bunch in AR is 1 ms. This leaves a gap of ∼300 ns for bunch extraction. The proton bunch will be extracted to Ring to Target Beam Transport (RTBT) line, with the help of fast kicker and septum magnets. In this paper, we present the details of the beam extraction scheme with suitable number of kicker magnets, and find out their optimal location and strength. Estimation of field error tolerances for kicker magnets is also presented. (author)

Magnetic measurements on the ring dipoles and quadrupoles for the Los Alamos proton storage ring

International Nuclear Information System (INIS)

Schermer, R.I.; Blind, B.; Jason, A.J.; Sawyer, G.A.

1985-01-01

This paper discusses magnetic measurements and shimming performed on the ring dipoles and quadrupoles for the Los Alamos Proton Storage Ring (PSR). For the dipoles, point-by-point field maps were obtained using a search coil that could be scanned over a three-dimensional grid. By appropriate machining of removable end blocks, all magnet lengths were adjusted to within 0.01% of a nominal value and all integrated multipoles were set within tolerance. Integrated fields of 20 PSR quadrupoles were measured using a rotating ''Morgan Coil'' and a digital spectrum analyzer. The magnets were shimmed to specifications by adjusting steel bolts threaded through the field clamps. 3 refs., 5 figs., 4 tabs

Development of an abort gap monitor for high-energy proton rings

International Nuclear Information System (INIS)

Beche, Jean-Francois; Byrd, John; De Santis, Stefano; Denes, Peter; Placidi, Massimo; Turner, William; Zolotorev, Max

2004-01-01

The fill pattern in proton synchrotrons usually features an empty gap, longer than the abort kicker raise time, for machine protection. This gap is referred to as the ''abort gap'' and any particles, which may accumulate in it due to injection errors and diffusion between RF buckets, would be lost inside the ring, rather than in the beam dump, during the kicker firing. In large proton rings, due to the high energies involved, it is vital to monitor the build up of charges in the abort gap with a high sensitivity. We present a study of an abort gap monitor based on a photomultiplier with a gated microchannel plate, which would allow for detecting low charge densities by monitoring the synchrotron radiation emitted. We show results of beam test experiments at the Advanced Light Source using a Hamamatsu 5916U MCP-PMT and compare them to the specifications for the Large Hadron Collider

Development of an Abort Gap Monitor for High-Energy Proton Rings

International Nuclear Information System (INIS)

Beche, J.-F.; Byrd, J.; De Santis, S.; Denes, P.; Placidi, M.; Turner, W.; Zolotorev, M.

2004-01-01

The fill pattern in proton synchrotrons usually features an empty gap, longer than the abort kicker raise time, for machine protection. This gap is referred to as the 'abort gap', and any particles, which may accumulate in it due to injection errors and diffusion between RF buckets, would be lost inside the ring, rather than in the beam dump, during the kicker firing. In large proton rings, due to the high energies involved, it is vital to monitor the build up of charges in the abort gap with a high sensitivity. We present a study of an abort gap monitor based on a photomultiplier with a gated microchannel plate, which would allow for detecting low charge densities by monitoring the synchrotron radiation emitted. We show results of beam test experiments at the Advanced Light Source using a Hamamatsu 5916U MCP-PMT and compare them to the specifications for the Large Hadron Collider

Instability of equatorial protons in Jupiter's mid-magnetosphere

International Nuclear Information System (INIS)

Northrop, T.G.; Schardt, A.W.

1980-01-01

Two different models for the distribution function are fit to the Jovian protons seen by Pioneer 10 inbound. The models reproduce the observed energy and angular distributions. These models are then used to assess the collisionless mirror instability. Because of the pancake proton angular distributions in the equatorial ring current region, the ring current particle population appears to be mirror unstable at times, with instability growth rates of approx.10 min. Such a time is consistent with observed proton flux autocorrelation times. An instability such as this (there are other candidates) may be responsible for the previously established proton flux flowing parallel to the magnetic field away from the equatorial region

The earth's ring current - Present situation and future thrusts

Science.gov (United States)

Williams, D. J.

1987-01-01

Particle distributions, currents, and the ring current situation prior to the August 1984 launch of the AMPTE Charge Composition Explorer (CCE) are discussed. CCE results which demonstrate the capability of these new measurements to pursue questions of ring current sources, energization, and transport are presented. Consideration is given to various ring current generation mechanisms which have been discussed in the literature, and a two-step generation process which to a certain extent unifies the previous mechanisms is presented. The first in-situ global observations of ring current decay as obtained through the detection of energetic neutral atoms generated by charge exchange interactions between the ring current and hydrogen geocorona are discussed, as well as the possibility of using the detection of energetic neutral atoms to obtain global images of the earth's ring current.

Space Weather Effects Produced by the Ring Current Particles

Science.gov (United States)

Ganushkina, Natalia; Jaynes, Allison; Liemohn, Michael

2017-11-01

One of the definitions of space weather describes it as the time-varying space environment that may be hazardous to technological systems in space and/or on the ground and/or endanger human health or life. The ring current has its contributions to space weather effects, both in terms of particles, ions and electrons, which constitute it, and magnetic and electric fields produced and modified by it at the ground and in space. We address the main aspects of the space weather effects from the ring current starting with brief review of ring current discovery and physical processes and the Dst-index and predictions of the ring current and storm occurrence based on it. Special attention is paid to the effects on satellites produced by the ring current electrons. The ring current is responsible for several processes in the other inner magnetosphere populations, such as the plasmasphere and radiation belts which is also described. Finally, we discuss the ring current influence on the ionosphere and the generation of geomagnetically induced currents (GIC).

Run permit software for the proton storage ring

International Nuclear Information System (INIS)

Bair, S.S.

1985-01-01

The Run Permit system is intended to protect equipment from radiation effects caused by having beam enabled when required equipment is not operational. This system will not allow beam unless certain devices are ready and will drop beam if any of these devices become inoperative. A system to provide such protection might be implemented in hardware. However, because the several operating modes of the Proton Storage Ring/Weapons Neutron Research facility require certain devices to be in different states (depending on mode), a dynamic configuration capability is needed, that is, a software solution is more feasible

S.C. correction coils and magnets for the HERA proton ring

International Nuclear Information System (INIS)

Daum, C.; Geerinck, J.; Schmueser, P.

1986-05-01

The quadrupole and sextupole correction coils of the HERA proton ring are mounted on the cold beam pipe inside the main dipole magnets. Superferric dipole magnets for orbit correction are located adjacent to the main quadrupole magnets in a common cryostat which also contains the beam monitor. The design, manufacture and performance of both types of correction elements are described. (orig.)

Spin flipping a stored polarized proton beam at the IUCF cooler ring

International Nuclear Information System (INIS)

Phelps, R.A.

1995-01-01

We recently studied the spin flip of a vertically polarized 139 MeV proton beam stored in the IUCF Cooler Ring. We used an rf solenoid to induce a depolarizing resonance in the ring; we flipped the spin by varying the solenoid field's frequency through this resonance. We found a polarization loss after multiple spin flips less than 0.1% per flip; we also found that this loss increased for very slow frequency changes. This spin flip could reduce systematic errors in stored polarization beam experiments by allowing frequent beam polarization reversals during the experiment. copyright 1995 American Institute of Physics

Proton injection and RF capture in the national spallation neutron source

International Nuclear Information System (INIS)

Luccio, A.U.; Beebe-Wang, J.; Maletic, D.

1997-01-01

The accelerator system for the 1 to 5 MW National Spallation Neutron Source (NSNS) consists of a linac followed by a 1 GeV proton accumulator ring. Since the ring is a very high current machine, the injection and rf capture of the protons is deeply affected by transverse and longitudinal space charge effects. Results of numerical simulation of the process are presented together with considerations on methods and results of space charge treatment in high intensity proton storage rings

Evolution of the ring current during two geomagnetic storms

International Nuclear Information System (INIS)

Lui, A.T.Y.; McEntire, R.W.; Krimigis, S.M.

1987-01-01

The progressive developments in the radial profiles of the particle pressure, plasma beta, and electric currents of the storm time ring current are investigated with data from the medium energy particle analyzer on the AMPTE Charged Particle Explorer spacecraft. Measurements of ions from 25 keV to 1 MeV, which carry 70--85% of the energy density of the entire ring current population, are used in this work. Two geomagnetic storms in September of 1984 are selected and four traversals of the equatorial ring current region during the course of each storm are studied. It is shown that enhancements in the particle pressure occur initially in the outer region and reach the inner region in the late phase of the storm. Structures suggestive of multiple particle injections are seen in the pressure profile. The leading and trailing edges of the particle injection structures are associated, respectively, with the depressions and enhancements of the westward current densities of the ring current. Plasma beta occasionally increases to values of the order of 1 in some regions of the ring current from prestorm values of the order of 0.1 or less. It is also found that the location of the maximum ring current particle pressure can be several earth radii from where the most intense westward ring current flows. This is a consequence of the dominance of pressure gradient current over the current associated with the magnetic field line curvature and particle anisotropy. copyright American Geophysical Union 1987

Storm-time ring current: model-dependent results

Directory of Open Access Journals (Sweden)

N. Yu. Ganushkina

2012-01-01

Full Text Available The main point of the paper is to investigate how much the modeled ring current depends on the representations of magnetic and electric fields and boundary conditions used in simulations. Two storm events, one moderate (SymH minimum of −120 nT on 6–7 November 1997 and one intense (SymH minimum of −230 nT on 21–22 October 1999, are modeled. A rather simple ring current model is employed, namely, the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM, in order to make the results most evident. Four different magnetic field and two electric field representations and four boundary conditions are used. We find that different combinations of the magnetic and electric field configurations and boundary conditions result in very different modeled ring current, and, therefore, the physical conclusions based on simulation results can differ significantly. A time-dependent boundary outside of 6.6 RE gives a possibility to take into account the particles in the transition region (between dipole and stretched field lines forming partial ring current and near-Earth tail current in that region. Calculating the model SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke (DPS relation gives larger and more realistic values, since the currents are calculated in the regions with nondipolar magnetic field. Therefore, the boundary location and the method of SymH* calculation are of key importance for ring current data-model comparisons to be correctly interpreted.

Generation of stable mixed-compact-toroid rings by inducing plasma currents in strong E rings

International Nuclear Information System (INIS)

Jayakumar, R.; Taggart, D.P.; Parker, M.R.; Fleischmann, H.H.

1989-01-01

In the RECE-Christa device, hybrid-type compact toroid rings are generated by inducing large toroidal plasma currents I rho in strong electron rings using a thin induction coil positioned along the ring axis. Starting from field-reversal values δ ο = 50 - 120 percent of the original pure fast-electron ring, the induced plasma current I rho raises δ to a maximum value of up to 240 percent with I rho contributing more than 50 percent of the total ring current. Quite interestingly, the generated hybrid compact toroid configurations appear gross-stable during the full I rho pulse length (half-amplitude width about 100 μs)

Fano resonance and persistent current of a quantum ring

International Nuclear Information System (INIS)

Xiong Yongjian; Liang Xianting

2004-01-01

We investigate electron transport and persistent current of a quantum ring weakly attached to current leads. Assuming there is direct coupling (weakly or strongly) between two leads, electrons can transmit by the inter-lead coupling or tunneling through the quantum ring. The interference between the two paths yields asymmetric Fano line shape for conductance. In presence of interior magnetic flux, there is persistent current along the ring with narrow resonance peaks. The positions of the conductance resonances and the persistent current peaks correspond to the quasibound levels of the closed ring. This feature is helpful to determine the energy spectrum of the quantum ring. Our results show that the proposed setup provides a tunable Fano system

Energetic Proton Spectra Measured by the Van Allen Probes

Science.gov (United States)

Summers, Danny; Shi, Run; Engebretson, Mark J.; Oksavik, Kjellmar; Manweiler, Jerry W.; Mitchell, Donald G.

2017-10-01

We test the hypothesis that pitch angle scattering by electromagnetic ion cyclotron (EMIC) waves can limit ring current proton fluxes. For two chosen magnetic storms, during 17-20 March 2013 and 17-20 March 2015, we measure proton energy spectra in the region 3 ≤ L ≤ 6 using the RBSPICE-B instrument on the Van Allen Probes. The most intense proton spectra are observed to occur during the recovery periods of the respective storms. Using proton precipitation data from the POES (NOAA and MetOp) spacecraft, we deduce that EMIC wave action was prevalent at the times and L-shell locations of the most intense proton spectra. We calculate limiting ring current proton energy spectra from recently developed theory. Comparisons between the observed proton energy spectra and the theoretical limiting spectra show reasonable agreement. We conclude that the measurements of the most intense proton spectra are consistent with self-limiting by EMIC wave scattering.

Design of a power amplifier for the LAMPF proton storage ring transverse damper system

International Nuclear Information System (INIS)

Lunsford, J.S.

1981-01-01

A power amplifier has been designed to drive the 50-Ω stripline deflection structures in the transverse active damper of the Los Alamos 800-MeV Proton Storage Ring (PSR). The unit will provide 600-V peak-to-peak with a dc-to-100-MHz bandwidth. Other important characteristics include < 40-ns delay time, 50-dB voltage gain, and 4-ns risetime with < 5% overshoot and ringing. Because of the current-drive properties of the amplifier, two amplifiers could be combined to provide over 1000-V peak-to-peak into 50 Ω, with very little bandwidth degradation. Components in the power amplifier that represent new designs are a 20-tube distributed-amplifier output stage; a driver stage, using VMOS FET and bipolar transistors; a high-voltage probe, with good dc stability and 150-MHz bandwidth; a transient suppressor circuit, using PIN diodes to protect the transistorized drivers from tube arcing; a nonlinear amplifier to compensate for the nonlinear characteristics of the distributed amplifier; and a first-fail indicator circuit to aid in locating the prime causes of equipment failures

Coherent instabilities of proton beams in accelerators and storage rings - experimental results, diagnosis and cures

International Nuclear Information System (INIS)

Schnell, W.

1977-01-01

The author discusses diagnosis and cure of proton beam instabilities in accelerators and storage rings. Coasting beams and bunched beams are treated separately and both transverse and longitudinal instabilities are considered. (B.D.)

The PEP [positron-electron-proton] electron-positron ring: PEP Stage I

International Nuclear Information System (INIS)

Rees, J.R.

1974-01-01

The first stage of the positron-electron-proton (PEP) colliding-beam system which has been under joint study by a Lawrence Berkeley Laboratory-Stanford Linear Accelerator Center team for the past two years, will be the electron-positron storage ring. The physics justification for the e/sup /plus//e/sup /minus// ring is summarized briefly and the proposed facility is described. The ring will have six arcs having gross radii of about 220 m and six interaction regions located at the centers of straight sections about 130 m long. The longitudinal distance left free for experimental apparatus around the interaction regions will be 20 m. The range of operating beam energies will be from 5 GeV to 15 GeV. The design luminosity at 15 GeV will be 10 32 cm/sup /minus/2/s/sup/minus/1/, and the luminosity will vary approximately as the square of the beam energy. Alternative methods under consideration for adjusting the beam cross-section are discussed. The designs of the storage ring subsystems and of the conventional facilities including the experimental halls at the interaction regions are described. 7 refs., 8 figs., 3 tabs

Carbon filament beam profile monitor for high energy proton-antiproton storage rings

International Nuclear Information System (INIS)

Evans, L.R.; Shafer, R.E.

1979-01-01

The measurement of the evolution of the transverse profile of the stored beams in high energy proton storage rings such as the p-anti p colliders at CERN and at FNAL is of considerable importance. In the present note, a simple monitor is discussed which will allow almost non-destructive measurement of the profile of each individual proton and antiproton bunch separately. It is based on the flying wire technique first used at CEA and more recently at the CPS. A fine carbon filament is passed quickly through the beam, acting as a target for secondary particle production. The flux of secondary particles is measured by two scintillator telescopes, one for protons and one for antiprotons, having an angular acceptance between 30 and 100 mrad. Measurements of secondary particle production performed at FNAL in this angular range show that a very respectable flux can be expected

A proposal of a beam injection device for the proton storage ring of JAERI neutron science project

International Nuclear Information System (INIS)

Suzuki, Yasuo

1998-01-01

A new injection device (a charge-exchange device) with light and magnetic field, is proposed for a proton storage ring of JAERI Neutron Science Project. This injection device is composed of a neutralizer and an ionizer. The neutralizer strips electrons of H 0 beam into H - one with the undulator magnetic field. The ionizer which is composed of undulator magnets and an optical resonator placed along a straight part in the storage ring, can ionize effectively the H 0 beam excited to n=3 level by a laser beam into H + one. Adopting the 2nd harmonics of Nd : YAG laser, the powerful laser on the market can be used, and the required items of the technological development can be minimized. The energy of the particle beam, however, should be accelerated up to 1.587 GeV by 6% increase from 1.5 GeV. In this device, the non-charge-exchange rate and beam-spill can be minimized by decreasing the deflection angle of the beam which occurs at the charge-exchange process. This method can be realized with exiting technologies and there are not any effects on the trajectory of the ring-circulating proton beam due to scatterings by the foil as the usual charge-exchange devices. This device, therefore, will be an optimal and highly effective method of the least beam-spill as the injector of the high power proton storage ring. (author)

Acceleration of polarized protons and deuterons in the ion collider ring of JLEIC

Science.gov (United States)

Kondratenko, A. M.; Kondratenko, M. A.; Filatov, Yu N.; Derbenev, Ya S.; Lin, F.; Morozov, V. S.; Zhang, Y.

2017-07-01

The figure-8-shaped ion collider ring of Jefferson Lab Electron-Ion Collider (JLEIC) is transparent to the spin. It allows one to preserve proton and deuteron polarizations using weak stabilizing solenoids when accelerating the beam up to 100 GeV/c. When the stabilizing solenoids are introduced into the collider’s lattice, the particle spins precess about a spin field, which consists of the field induced by the stabilizing solenoids and the zero-integer spin resonance strength. During acceleration of the beam, the induced spin field is maintained constant while the resonance strength experiences significant changes in the regions of “interference peaks”. The beam polarization depends on the field ramp rate of the arc magnets. Its component along the spin field is preserved if acceleration is adiabatic. We present the results of our theoretical analysis and numerical modeling of the spin dynamics during acceleration of protons and deuterons in the JLEIC ion collider ring. We demonstrate high stability of the deuteron polarization in figure-8 accelerators. We analyze a change in the beam polarization when crossing the transition energy.

Multielement analysis of Picea rubens Sarg. Three-rings by proton-induced x-ray emission

International Nuclear Information System (INIS)

Hall, G.S.

1984-01-01

A 3.7 MeV external proton beam was employed to produce X-rays in Picea rubens Sarg. (red spruce). Intra-annual growth rings and several elements were quantitatively determined (P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Sr). The PIXE experimental set-up, rapid sample preparation methods, and some interesting observations are discussed. In addition, statistical analysis of the tree-ring element concentrations revealed that K, Cl, and Ca were slightly translocated whereas the other elements detected were not. 15 references, 1 figure, 1 table

Comparing Sources of Storm-Time Ring Current O+

Science.gov (United States)

Kistler, L. M.

2015-12-01

The first observations of the storm-time ring current composition using AMPTE/CCE data showed that the O+ contribution to the ring current increases significantly during storms. The ring current is predominantly formed from inward transport of the near-earth plasma sheet. Thus the increase of O+ in the ring current implies that the ionospheric contribution to the plasma sheet has increased. The ionospheric plasma that reaches the plasma sheet can come from both the cusp and the nightside aurora. The cusp outflow moves through the lobe and enters the plasma sheet through reconnection at the near-earth neutral line. The nightside auroral outflow has direct access to nightside plasma sheet. Using data from Cluster and the Van Allen Probes spacecraft, we compare the development of storms in cases where there is a clear input of nightside auroral outflow, and in cases where there is a significant cusp input. We find that the cusp input, which enters the tail at ~15-20 Re becomes isotropized when it crosses the neutral sheet, and becomes part of the hot (>1 keV) plasma sheet population as it convects inward. The auroral outflow, which enters the plasma sheet closer to the earth, where the radius of curvature of the field line is larger, does not isotropize or become significantly energized, but remains a predominantly field aligned low energy population in the inner magnetosphere. It is the hot plasma sheet population that gets accelerated to high enough energies in the inner magnetosphere to contribute strongly to the ring current pressure. Thus it appears that O+ that enters the plasma sheet further down the tail has a greater impact on the storm-time ring current than ions that enter closer to the earth.

High intensity proton accelerator and its application (Proton Engineering Center)

International Nuclear Information System (INIS)

Tanaka, Shun-ichi

1995-01-01

A plan called PROTON ENGINEERING CENTER has been proposed in JAERI. The center is a complex composed of research facilities and a beam shape and storage ring based on a proton linac with an energy of 1.5 GeV and an average current of 10 mA. The research facilities planned are OMEGA·Nuclear Energy Development Facility, Neutron Facility for Material Irradiation, Nuclear Data Experiment Facility, Neutron Factory, Meson Factory, Spallation Radioisotope Beam Facility, and Medium Energy Experiment Facility, where high intensity proton beam and secondary particle beams such as neutrons, π-mesons, muons, and unstable isotopes originated from the protons are available for promoting the innovative research of nuclear energy and basic science and technology. (author)

Emittance growth induced by electron cloud in proton storage rings

CERN Document Server

Benedetto, Elena; Coppa, G

2006-01-01

In proton and positron storage rings with many closely spaced bunches, a large number of electrons can accumulate in the beam pipe due to various mechanisms (photoemission, residual gas ionization, beam-induced multipacting). The so-formed electron cloud interacts with the positively charged bunches, giving rise to instabilities, emittance growth and losses. This phenomenon has been observed in several existing machines such as the CERN Super Proton Synchrotron (SPS), whose operation has been constrained by the electron-cloud problem, and it is a concern for the Large Hadron Collider (LHC), under construction at CERN. The interaction between the beam and the electron cloud has features which cannot be fully taken into account by the conventional and known theories from accelerators and plasma physics. Computer simulations are indispensable for a proper prediction and understanding of the instability dynamics. The main feature which renders the beam-cloud interactions so peculiar is that the the electron cloud...

Halo and space charge issues in the SNS Ring

International Nuclear Information System (INIS)

Fedotov, A.V.; Abell, D.T.; Beebe-Wang, J.; Lee, Y.Y.; Malitsky, N.; Wei, J.; Gluckstern, R.L.

2000-01-01

The latest designs for high-intensity proton rings require minimizing beam-induced radioactivation of the vacuum chamber. Although the tune depression in the ring is much smaller than in high-intensity linacs, space-charge contributions to halo formation and, hence, beam loss may be significant. This paper reviews our current understanding of halo formation issues for the Spallation Neutron Source (SNS) accumulator ring

Halo and space charge issues in the SNS Ring

Energy Technology Data Exchange (ETDEWEB)

Fedotov, A.V.; Abell, D.T.; Beebe-Wang, J.; Lee, Y.Y.; Malitsky, N.; Wei, J.; Gluckstern, R.L.

2000-06-30

The latest designs for high-intensity proton rings require minimizing beam-induced radioactivation of the vacuum chamber. Although the tune depression in the ring is much smaller than in high-intensity linacs, space-charge contributions to halo formation and, hence, beam loss may be significant. This paper reviews our current understanding of halo formation issues for the Spallation Neutron Source (SNS) accumulator ring.

Quantum rings in magnetic fields and spin current generation.

Science.gov (United States)

Cini, Michele; Bellucci, Stefano

2014-04-09

We propose three different mechanisms for pumping spin-polarized currents in a ballistic circuit using a time-dependent magnetic field acting on an asymmetrically connected quantum ring at half filling. The first mechanism works thanks to a rotating magnetic field and produces an alternating current with a partial spin polarization. The second mechanism works by rotating the ring in a constant field; like the former case, it produces an alternating charge current, but the spin current is dc. Both methods do not require a spin-orbit interaction to achieve the polarized current, but the rotating ring could be used to measure the spin-orbit interaction in the ring using characteristic oscillations. On the other hand, the last mechanism that we propose depends on the spin-orbit interaction in an essential way, and requires a time-dependent magnetic field in the plane of the ring. This arrangement can be designed to pump a purely spin current. The absence of a charge current is demonstrated analytically. Moreover, a simple formula for the current is derived and compared with the numerical results.

Persistent currents in an ensemble of isolated mesoscopic rings

International Nuclear Information System (INIS)

Altland, A.; Iida, S.; Mueller-Groelling, A.; Weidenmueller, H.A.

1992-01-01

In this work, the authors calculate the persistent current induced at zero temperature by an external, constant, and homogeneous magnetic field in an ensemble of isolated mesoscopic rings. In each ring, the electrons are assumed to move independently under the influence of a Gaussian white noise random impurity potential. They account for the magnetic field only in terms of the flux threading each ring, without considering the field present in the body of the ring. Particular attention is paid to the constraint of integer particle number on each ring. The authors evaluate the persistent current non-perturbatively, using a generating functional involving Grassmann integration. The magnetic flux threading each ring breaks the orthogonal symmetry of the formalism; forcing us to calculate explicitly the orthogonal-unitary crossover. 24 refs., 1 fig

Conformational analysis of the deoxyribofuranose ring in DNA by means of sums of proton-proton coupling constants: A graphical method

International Nuclear Information System (INIS)

Rinkel, L.J.; Altona, C.

1987-01-01

A graphical method is presented for the conformational analysis of the sugar ring in DNA fragments by means of proton-proton couplings. The coupling data required for this analysis consist of sums of couplings, which are referred to as sigma 1' (= J1'2' + J1'2''), sigma 2' (= J1'2' + J2'3' + J2'2''), sigma 2'' (= J1'2'' + J2''3' + J2'2'') and sigma 3' (= J2'3' + J2''3' + J3'4'). These sums of couplings correspond to the distance between the outer peaks of the H1', H2', H2'' and H3' [31P] resonances, respectively, (except for sigma 2' and sigma 2'' in the case of a small chemical shift difference between the H2' and H2'' resonances) and can often be obtained from 1H-NMR spectra via first-order measurement, obviating the necessity of a computer-assisted simulation of the fine structure of these resonances. Two different types of graphs for the interpretation of the coupling data are discussed: the first type of graph serves to probe as to whether or not the sugar ring occurs as a single conformer, and if so to analyze the coupling data in terms of the geometry of this sugar ring. In cases where the sugar ring does not occur as a single conformer, but as a blend of N- and S-type sugar puckers, the second type of graph is used to analyze the coupling data in terms of the geometry and population of the most abundant form. It is shown that the latter type of analysis can be carried out on the basis of experimental values for merely sigma 1',sigma 2' and sigma 2'', without any assumptions or restrictions concerning a relation between the geometry of the N- and S-type conformer. In addition, the question is discussed as to how insight can be gained into the conformational purity of the sugar ring from the observed fine structure of the H1' resonance

An energy recovery electron linac-on-ring collider

International Nuclear Information System (INIS)

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

2000-01-01

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 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

The Ring Current Response to Solar and Interplanetary Storm Drivers

Science.gov (United States)

Mouikis, C.; Kistler, L. M.; Bingham, S.; Kronberg, E. A.; Gkioulidou, M.; Huang, C. L.; Farrugia, C. J.

2014-12-01

The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), corotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure, in turn, change the global magnetic field, controlling the transport of the radiation belts. To quantitatively determine the field changes during a storm throughout the magnetosphere, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. Because the measured ring current energy spectra depend not only on local processes, but also on the history of the ions along their entire drift path, measurements of ring current energy spectra at two or more locations can be used to strongly constrain the time dependent magnetic and electric fields. In this study we use data predominantly from the Cluster and the Van Allen Probes, covering more than a full solar cycle (from 2001 to 2014). For the period 2001-2012, the Cluster CODIF and RAPID measurements of the inner magnetosphere are the primary data set used to monitor the storm time ring current variability. After 2012, the Cluster data set complements the data from the Van Allen Probes HOPE and RBSPICE instruments, providing additional measurements from different MLT and L shells. Selected storms from this periods, allow us to study the ring current dynamics and pressure changes, as a function of L shell, magnetic local time, and the type of interplanetary disturbances.

4-twist helix snake to maintain polarization in multi-GeV proton rings

Science.gov (United States)

Antoulinakis, F.; Chen, Y.; Dutton, A.; Rossi De La Fuente, E.; Haupert, S.; Ljungman, E. A.; Myers, P. D.; Thompson, J. K.; Tai, A.; Aidala, C. A.; Courant, E. D.; Krisch, A. D.; Leonova, M. A.; Lorenzon, W.; Raymond, R. S.; Sivers, D. W.; Wong, V. K.; Yang, T.; Derbenev, Y. S.; Morozov, V. S.; Kondratenko, A. M.

2017-09-01

Solenoid Siberian snakes have successfully maintained polarization in particle rings below 1 GeV, but never in multi-GeV rings, because the spin rotation by a solenoid is inversely proportional to the beam momentum. High energy rings, such as Brookhaven's 255 GeV Relativistic Heavy Ion Collider (RHIC), use only odd multiples of pairs of transverse B-field Siberian snakes directly opposite each other. When it became impractical to use a pair of Siberian Snakes in Fermilab's 120 GeV /c Main Injector, we searched for a new type of single Siberian snake that could overcome all depolarizing resonances in the 8.9 - 120 GeV /c range. We found that a snake made of one 4-twist helix and 2 dipoles could maintain the polarization. This snake design could solve the long-standing problem of significant polarization loss during acceleration of polarized protons from a few GeV to tens of GeV, such as in the AGS, before injecting them into multi-hundred GeV rings, such as RHIC.

4-twist helix snake to maintain polarization in multi-GeV proton rings

International Nuclear Information System (INIS)

Antoulinakis, F.; Chen, Y.; Dutton, A.; Rossi De La Fuente, E.; Haupert, S.

2017-01-01

Solenoid Siberian snakes have successfully maintained polarization in particle rings below 1 GeV, but never in multi-GeV rings, because the spin rotation by a solenoid is inversely proportional to the beam momentum. High energy rings, such as Brookhaven’s 255 GeV Relativistic Heavy Ion Collider (RHIC), use only odd multiples of pairs of transverse B-field Siberian snakes directly opposite each other. When it became impractical to use a pair of Siberian Snakes in Fermilab’s 120 GeV/c Main Injector, we searched for a new type of single Siberian snake that could overcome all depolarizing resonances in the 8.9–120 GeV/c range. We found that a snake made of one 4-twist helix and 2 dipoles could maintain the polarization. Here, this snake design could solve the long-standing problem of significant polarization loss during acceleration of polarized protons from a few GeV to tens of GeV, such as in the AGS, before injecting them into multi-hundred GeV rings, such as RHIC.

Development of capacitive beam position, beam current and Schottky-signal monitors for the Cryogenic Storage Ring (CSR)

International Nuclear Information System (INIS)

Laux, Felix

2011-01-01

In this thesis novel techniques based on capacitive pickups for the determination of the beam current, the beam position and the Schottky-signal in storage rings have been developed. Beam current measurements at the heavy ion storage ring TSR with a capacitive pickup have been found in very good agreement with the theory. Using this device the accurate measurement of beam currents at the TSR far below 1 μA is now possible. This method will also be used at the Cryogenic Storage Ring (CSR) at which beam currents in the range of 1 nA-1 μA are expected. For the first time, position measurements with a resonant amplifier system for capacitive pickups have been examined at the TSR for later use of this technique in the CSR. With this method an increased signal-to-noise ratio can be achieved using a parallel inductance. A comparison with measurements using the rest gas beam profile monitor has shown very good agreement even at very low intensities. Experiments with the cryo-capable electronics for the CSR beam position monitors have shown an achievable quality factor of Q=500, resulting in the prospect of precise position measurements at the CSR even at very low beam currents. The CSR Schottky-Pickup will also be equipped with a resonant amplifier system with a comparable quality factor. An estimation of the signal-to-noise ratio suggests a detection limit of a few protons. (orig.)

Stability of large orbit, high-current particle rings

International Nuclear Information System (INIS)

Lovelace, R.V.E.

1994-01-01

A review is made of theory of the low-frequency stability of large orbit, high-current particle rings which continue to be of interest for compact fusion systems. The precession mode was the first mode predicted by Furth and observed by Christofilos to be unstable under certain conditions. Subsequently, many detailed studies have been made of the stability of particle rings- different modes, different ring geometries, systems with/without a toroidal B field, and sytems with/without a current carrying plasma component. The possibly dangerous modes are still thought to include the precession mode, the tilting mode, and the low order kink modes. copyright American Institute of Physics

A pinger system for the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Hardek, T.W.; Thiessen, H.A.

1991-01-01

Developers at the Proton Storage Ring have long desired a modulator and electrode combination capable of kicking the 800-MeV proton beam enough to conduct tune measurements with full intensity beams. At present this has been accomplished by reducing the voltage on one extraction kicker modulator and turning the other off. This method requires that all of the accumulated beam be lost on the walls of the vacuum chamber. In addition to tune measurements a more recent desire is to sweep out beam that may have leaked into the area between bunches. A four-meter electrode has been designed and constructed for the purpose. The design is flexible in that the electrode may be split in the center and rotated in order to provide vertical and horizontal electrodes each 2 meters long. In addition two solid-state pulse modulators that can provide 10kV in burst mode at up to 700 KHz have been purchased. This hardware and its intended use are described. 3 refs., 2 figs., 1 tab

Difference between ²JC2H3 and ²JC3H2 spin-spin couplings in heterocyclic five- and six-membered rings as a probe for studying σ-ring currents: a quantum chemical analysis.

Science.gov (United States)

Contreras, Rubén H; dos Santos, Francisco P; Ducati, Lucas C; Tormena, Cláudio F

2010-12-01

Adequate analyses of canonical molecular orbitals (CMOs) can provide rather detailed information on the importance of different σ-Fermi contact (FC) coupling pathways (FC term transmitted through the σ-skeleton). Knowledge of the spatial distribution of CMOs is obtained by expanding them in terms of natural bond orbitals (NBOs). Their relative importance for transmitting the σ-FC contribution to a given spin-spin coupling constants (SSCCs) is estimated by resorting to the expression of the FC term given by the polarisation propagator formalism. In this way, it is possible to classify the effects affecting such couplings in two different ways: delocalisation interactions taking place in the neighbourhood of the coupling nuclei and 'round the ring' effects. The latter, associated with σ-ring currents, are observed to yield significant differences between the FC terms of (2)J(C2H3) and (2)J(C3H2) SSCCs which, consequently, are taken as probes to gauge the differences in σ-ring currents for the five-membered rings (furan, thiophene, selenophene and pyrrol) and also for the six-membered rings (benzene, pyridine, protonated pyridine and N-oxide pyridine) used in the present study. Copyright © 2010 John Wiley & Sons, Ltd.

Proton and hydrogen formation by cyclohexyl benzene during overcharge of Li-ion batteries

Science.gov (United States)

Lee, Hochun; Kim, Soojin; Jeon, Jongho; Cho, Jeong-Ju

This study provides experimental evidence for proton and hydrogen formation caused by the anodic electropolymerization of cyclohexyl benzene (CHB), which is a popular electrolyte additive for overcharge protection of lithium-ion batteries (LIBs). It is found that considerable H 2 evolution is observed in overcharged LiCoO 2/graphite cells, especially when CHB is included as an electrolyte additive. In order to confirm the proton generation during the CHB oxidation, Pt/Pt-rotating ring disc electrode (RRDE) measurements are performed in 1 M Li(C 2F 5SO 2) 2N ethylene carbonate/ethyl methyl carbonate (1/2, v/v) solutions with and without CHB. The cathodic ring current is intimately correlated to the anodic disc current, and the cathodic reaction at the ring is determined to be the reduction of the proton. The proton generation efficiency during the CHB oxidation is as high as 90%. Proton liberation is also observed during the anodic decomposition of the electrolyte solvents, although it occurs in a much less stoichiometric way compared with that during the CHB oxidation.

4-twist helix snake to maintain polarization in multi-GeV proton rings

Directory of Open Access Journals (Sweden)

F. Antoulinakis

2017-09-01

Full Text Available Solenoid Siberian snakes have successfully maintained polarization in particle rings below 1 GeV, but never in multi-GeV rings, because the spin rotation by a solenoid is inversely proportional to the beam momentum. High energy rings, such as Brookhaven’s 255 GeV Relativistic Heavy Ion Collider (RHIC, use only odd multiples of pairs of transverse B-field Siberian snakes directly opposite each other. When it became impractical to use a pair of Siberian Snakes in Fermilab’s 120  GeV/c Main Injector, we searched for a new type of single Siberian snake that could overcome all depolarizing resonances in the 8.9–120  GeV/c range. We found that a snake made of one 4-twist helix and 2 dipoles could maintain the polarization. This snake design could solve the long-standing problem of significant polarization loss during acceleration of polarized protons from a few GeV to tens of GeV, such as in the AGS, before injecting them into multi-hundred GeV rings, such as RHIC.

The impact of exospheric neutral dynamics on ring current decay

Science.gov (United States)

Ilie, R.; Liemohn, M. W.; Skoug, R. M.; Funsten, H. O.; Gruntman, M.; Bailey, J. J.; Toth, G.

2015-12-01

The geocorona plays an important role in the energy budget of the Earth's inner magnetosphere since charge exchange of energetic ions with exospheric neutrals makes the exosphere act as an energy sink for ring current particles. Long-term ring current decay following a magnetic storm is mainly due to these electron transfer reactions, leading to the formation energetic neutral atoms (ENAs) that leave the ring current system on ballistic trajectories. The number of ENAs emitted from a given region of space depends on several factors, such as the energy and species of the energetic ion population in that region and the density of the neutral gas with which the ions undergo charge exchange. However, the density and structure of the exosphere are strongly dependent on changes in atmospheric temperature and density as well as charge exchange with the ions of plasmaspheric origin, which depletes the geocorona (by having a neutral removed from the system). Moreover, the radiation pressure exerted by solar far-ultraviolet photons pushes the geocoronal hydrogen away from the Earth in an anti-sunward direction to form a tail of neutral hydrogen. TWINS ENA images provide a direct measurement of these ENA losses and therefore insight into the dynamics of the ring current decay through interactions with the geocorona. We assess the influence of geocoronal neutrals on ring current formation and decay by analysis of the predicted ENA emissions using 6 different geocoronal models and simulations from the HEIDI ring current model during storm time. Comparison with TWINS ENA images shows that the location of the peak ENA enhancements is highly dependent on the distribution of geocoronal hydrogen density. We show that the neutral dynamics has a strong influence on the time evolution of the ring current populations as well as on the formation of energetic neutral atoms.

Energetic ion injection and formation of the storm-time symmetric ring current

Directory of Open Access Journals (Sweden)

L. Xie

2006-12-01

Full Text Available An extensive study of ring current injection and intensification of the storm-time ring current is conducted with three-dimensional (3-D test particle trajectory calculations (TPTCs. The TPTCs reveal more accurately the process of ring current injection, with the main results being the following: (1 an intense convection electric field can effectively energize and inject plasma sheet particles into the ring current region within 1–3 h. (2 Injected ions often follow chaotic trajectories in non-adiabatic regions, which may have implications in storm and ring current physics. (3 The shielding electric field, which arises as a consequence of enhanced convection and co-exists with the injection and convection electric field, may cause the original open trajectories of injected ions with higher energy to change into closed ones, thus playing a role in the formation of the symmetric ring current.

Eddy current inspection of stationary blade rings

International Nuclear Information System (INIS)

Krzywosz, K.J.; Hastings, S.N.

1994-01-01

Stationary turbine blade rings in a US power plant have experienced chloride-induced cracking. Failure analysis determined two types of cracking mechanisms: corrosion fatigue cracking confined to the leading edge of the outer shroud; and stress corrosion cracking present all over the blade surface. Fluorescent dye penetrant is typically used to detect and size cracks. However, it requires cleaning the blade rings by sandblasting to obtain reliable inspection results. Sand blasting in turn requires sealing the lower half of the turbine housing to prevent sand from contaminating the rest of the power plant components. Furthermore, both the penetrant examination and the removal of the sand are time consuming and costly. An alternative NDE technique is desirable which requires no pre-cleaning of the blade and a quick go/no-go inspection with the capability of estimating the crack length. This paper presents an innovative eddy current technique which meets the desired objectives by incorporating the use of specially designed contoured scanners equipped with an array of pancake coils. A set of eddy current pancake coils housed in three different scanners is used to manually scan and inspect the convex side of the stationary blade rings. The pancake coils are operated in a transmit/receive mode using two separate eddy current instruments. This paper presents the inspection concept, including scanner and probe designs, and test results from the various stages of multiple blade rings

A Study of Storage Ring Requirements for an Explosive Detection System Using NRA Method.

Energy Technology Data Exchange (ETDEWEB)

Wang, T. F. (Tai-Sen F.); Kwan, T. J. T. (Thomas J. T.)

2005-01-01

The technical feasibility of an explosives detection system based on the nuclear resonance absorption (NRA) of gamma rays in nitrogen-rich materials was demonstrated at Los Alamos National Laboratory (LANL) in 1993 by using an RFQ proton accelerator and a tomographic imaging prototype. The study is being continued recently to examine deployment of such an active interrogation system in realistic scenarios. The approach is to use an accelerator and electron-cooling-equipped storage rings(s) to provide the high quality and high current proton beam needed in a practical application. In this work, we investigate the requirements on the storage ring(s) with external gamma-ray-production target for a variant of the airport luggage inspection system considered in the earlier LANL experiments. Estimations are carried out based on the required inspection throughput, the gamma ray yield, the proton beam emittance growth due to scatters with the photon-production target, beam current limit in the storage ring, and the electron-cooling rate. Studies using scaling and reasonable parameter values indicate that it is possible to use no more than a few storage rings per inspection station in a practical NRA luggage inspection complex having more than ten inspection stations.

The uses of electrostatic bending and focussing elements for auxiliary storage rings in large proton collider tunnels

International Nuclear Information System (INIS)

Winn, D.R.

1987-01-01

The authors discuss the possibility of using electrostatic elements, instead of magnets, for bending and focusing in auxiliary electron storage rings in the tunnels of large proton accelerators. For example, in the proposed SSC tunnel, electron beam energies of --100 GeV appear to be possible. Benefits of electrostatic systems over conventional magnets in cost, aperture, beam dynamics, radiation hardness, and power are presented. Electrostatic element designs are discussed, as are applications to electron, anti-proton and heavy ion beams

ACCELERATION OF POLARIZED PROTONS AT RHIC

International Nuclear Information System (INIS)

HUANG, H.

2002-01-01

Relativistic Heavy Ion Collider (RHIC) ended its second year of operation in January 2002 with five weeks of polarized proton collisions. Polarized protons were successfully injected in both RHIC rings and maintained polarization during acceleration up to 100 GeV per ring using two Siberian snakes in each ring. This is the first time that polarized protons have been accelerated to 100 GeV. The machine performance and accomplishments during the polarized proton run will be reviewed. The plans for the next polarized proton run will be outlined

Ring current energy injection rate and solar wind-magnetosphere energy coupling

International Nuclear Information System (INIS)

Lee, L.C.; Kan, J.R.; Akasofu, S.-I.

1982-01-01

The purpose of this paper is to (i) formulate the ring current injection rate Usub(R) in terms of phisub(CT) (cross-tail potential drop) by assuming that the ring current formation is a direct consequence of an enhanced convection, (ii) examine the relationship between the injection rate Usub(R) and the power transferred from the solar wind to the magnetosphere and (iii) demonstrate that an enhanced convection indeed leads to the formation of the ring current. (author)

A Study of Storage Ring Requirements for an Explosive Detection System Using NRA Method

CERN Document Server

Wang, Tai-Sen

2005-01-01

The technical feasibility of an explosives detection system based on the nuclear resonance absorption (NRA) of gamma rays in nitrogen-rich materials was demonstrated at Los Alamos National Laboratory (LANL) in 1993 by using an RFQ proton accelerator and a tomographic imaging prototype.* The study is being continued recently to examine deployment of such an active interrogation system in realistic scenarios. The approach is to use a cyclotron and electron-cooling-equipped storage rings(s) to provide the high quality and high current proton beam needed in a practical application. In this work, we investigate the storage ring requirements for a variant of the airport luggage inspection system considered in the earlier LANL experiments. Estimations are carried out based on the required inspection throughput, the gamma ray yield, the proton beam emittance growth due to scattering with the photon-production target, beam current limit in the storage ring, and the electron cooling rate. Studies using scaling and reas...

Proton current measurements using the prompt gamma ray diagnostic technique

International Nuclear Information System (INIS)

Leeper, R.J.; Burns, E.J.T.; Johnson, D.J.; McMurtry, W.M.

1981-01-01

Prompt gamma ray signals from the nuclear reaction 7 Li(p,γ) 8 Be have been used to make time resolved proton current measurements. In these measurements, the proton beam was allowed to strike cylindrical thick lithium metal targets. The time integrated proton current was measured using gamma activation of copper via the reaction 63 Cu(γ,n) 62 Cu(β+). The positron activity of the copper sample was easily measured using coincidence counting techniques. The number of 62 Cu atoms produced per proton incident on a thick Li metal target was determined with separate calibration runs performed on the Sandia 2.5 MeV Van de Graaff accelerator. The time history of the prompt gamma production was measured using six EGG NPM-54 scintillator photomultiplier combinations shielded by 96.5 cm of concrete and 5.1 cm of Pb. The use of six scintillator photomultiplier combinations was necessary to increase the statistical precision of the data. The normalization of the prompt gamma time history data with the total time integrated proton-current measurement yielded the absolute time resolved proton current on target. Data from runs performed on the Sandia Proto I accelerator will be presented

Electric fields, electron production, and electron motion at the stripper foil in the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Plum, M.

1995-01-01

The beam instability at the Los Alamos Proton Storage Ring (PSR) most likely involves coupled oscillations between electrons and protons. For this instability to occur, there must be a strong source of electrons. Investigation of the various sources of electrons in the PSR had begun. Copious electron production is expected in the injection section because this section contains the stripper foil. This foil is mounted near the center of the beam pipe, and both circulating and injected protons pass through it, thus allowing ample opportunity for electron production. This paper discusses various mechanisms for electron production, beam-induced electric fields, and electron motion in the vicinity of the foil

Persistent currents in metallic rings containing a quantum dot

International Nuclear Information System (INIS)

Machura, Lukasz; Łuczka, Jerzy

2015-01-01

Currents in metallic rings with a quantum dot are studied in the framework of a Langevin equation for a magnetic flux passing through the ring. Two scenarios are considered: one in which thermal fluctuations of the dissipative part of the current are modeled by classical Johnson–Nyquist noise and one in which quantum character of thermal fluctuations is taken into account in terms of a quantum Smoluchowski equation. The impact of the amplitude and phase of the transmission coefficient of the electron through a quantum dot on current characteristics is analyzed. In tailored parameter regimes, both scenarios can exhibit the transition from para- to diamagnetic response of the current versus external magnetic flux. The type of response is more robust to changes of the amplitude of the transmission coefficient and more sensitive to changes of the phase around some values. - Highlights: • Langevin dynamics of the magnetic flux for classical and quantum Smoluchowski regimes. • Current-flux characteristics vs the amplitude and phase of the transmission coefficient. • Crucial role of the phase of the transmission coefficient. • Contribution to the development of effective control of current in mesoscopic rings

Electromagnetic pulse-driven spin-dependent currents in semiconductor quantum rings.

Science.gov (United States)

Zhu, Zhen-Gang; Berakdar, Jamal

2009-04-08

We investigate the non-equilibrium charge and spin-dependent currents in a quantum ring with a Rashba spin-orbit interaction (SOI) driven by two asymmetric picosecond electromagnetic pulses. The equilibrium persistent charge and persistent spin-dependent currents are investigated as well. It is shown that the dynamical charge and the dynamical spin-dependent currents vary smoothly with a static external magnetic flux and the SOI provides a SU(2) effective flux that changes the phases of the dynamic charge and the dynamic spin-dependent currents. The period of the oscillation of the total charge current with the delay time between the pulses is larger in a quantum ring with a larger radius. The parameters of the pulse fields control to a certain extent the total charge and the total spin-dependent currents. The calculations are applicable to nanometre rings fabricated in heterojunctions of III-V and II-VI semiconductors containing several hundreds of electrons.

Which hydrogen atom of toluene protonates PAH molecules in (+)-mode APPI MS analysis?

Science.gov (United States)

Ahmed, Arif; Ghosh, Manik Kumer; Choi, Myung Chul; Choi, Cheol Ho; Kim, Sunghwan

2013-03-01

A previous study (Ahmed, A. et al., Anal. Chem. 84, 1146-1151( 2012) reported that toluene used as a solvent was the proton source for polyaromatic hydrocarbon compounds (PAHs) that were subjected to (+)-mode atmospheric-pressure photoionization. In the current study, the exact position of the hydrogen atom in the toluene molecule (either a methyl hydrogen or an aromatic ring hydrogen) involved in the formation of protonated PAH ions was investigated. Experimental analyses of benzene and anisole demonstrated that although the aromatic hydrogen atom of toluene did not contribute to the formation of protonated anthracene, it did contribute to the formation of protonated acridine. Thermochemical data and quantum mechanical calculations showed that the protonation of anthracene by an aromatic ring hydrogen atom of toluene is endothermic, while protonation by a methyl hydrogen atom is exothermic. However, protonation of acridine by either an aromatic ring hydrogen or a methyl hydrogen atom of toluene is exothermic. The different behavior of acridine and anthracene was attributed to differences in gas-phase basicity. It was concluded that both types of hydrogen in toluene can be used for protonation of PAH compounds, but a methyl hydrogen atom is preferred, especially for non-basic compounds.

Thin layer activation (TLA) experiment of piston ring F.J product by using nuclear facility proton beam 12.5 MeV

International Nuclear Information System (INIS)

Sudarmono; Silakhuddin

2002-01-01

The experiment of thin layer activation of piston ring F.J product, was done. The purpose of this experiment are to measure material wearing level by using concentration method. The experiment was carried out by activated piston ring proton beam with energy 12,5 MeV and beam current 1 μA for 30 minutes then was continued by wearing process. The measurement of the wear result activity was carried out by pouring the total of volume of lubricant oil for radioactivity measurement. Measurement of the activity level used the gamma spectroscopy. The minimum wearing duration that can detects a wear was 5 hours. The activity count was 1.230 pulse per 30 seconds which is in accordance with a wear in order of 8 mg of Fe material on 1 liter oil lubricant, this result is same with the result of T. Delvigne namely is less than 10 mgr

Fast-extraction modulators for Los Alamos Scientific LaboratorY Proton Storage Ring

International Nuclear Information System (INIS)

Nunnally, W.C.; Hudgings, D.W.; Sarjeant, W.J.

1980-01-01

The development of a short-bunch mode fast-extraction modulator for the LASL proton storage ring has made necessary the design and development of a resonant transformer charging circuit and the design of a new FIB line circuit to provide bipolar pulse outputs with low prepulse, postpulse, and an optimum high-voltage switch environments. The systems are now being developed to operate reliably at the high-average powers required. The short-bunch mode fast-extraction modulator prototype is presently operating. The initial construction of the long-bunch mode fast-extraction modulator prototype is under way, with results expected within the year

Tilt stability of rotating current rings with passive conductors

International Nuclear Information System (INIS)

Zweibel, E.G.; Pomphrey, N.

1984-12-01

We study the combined effects of rotation and resistive passive conductors on the stability of a rigid current in an external magnetic field. We present numerical and approximate analytical solutions to the equations of motion, which show that the ring is always tilt unstable on the resistive decay timescale of the conductors, although rotation and eddy currents may stabilize it over short times. Possible applications of our model include spheromaks which rotate or which are encircled by energetic particle rings

The role of substorms in the formation of the ring current

International Nuclear Information System (INIS)

Rostoker, G.

1996-01-01

It has long been recognized that the formation of the terrestrial ring current is accompanied by strong substorm expansive phase activity in the auroral oval. While large amplitude substorm activity seems to be a prerequisite for ring current formation to take place, it has long been puzzling as to why some large amplitude substorm activity in the auroral oval is not associated with significant ring current development. In this paper I shall outline the basis for the renovated boundary layer dynamics model of magnetospheric substorms showing how the onset of the substorm expansive phase can be associated with a sudden decrease in shielding space charge in the region of the near-Earth plasma sheet threaded by Region 2 field-aligned currents. I shall suggest that an episode of sufficiently large southward IMF lasting over a sufficiently lengthy period of time can lead to a sequence of substorm expansive phases, each one being initiated closer to the Earth than the previous one. Each expansive phase is attributed to a sudden decrease in radially localized cross-tail current (viz. a decrease in shielding space charge) and with each onset the inner edge of the plasma sheet moves inward. The inductive electric field associated with each crosstail current decrease is responsible for the acceleration of already energetic particles to energies of significance for ring current formation. Only when the inner edge of the crosstail current is sufficiently close to the Earth do the acceleration processes associated with substorm onset produce a long lived ring current. copyright 1996 American Institute of Physics

Effects of substorms on the stormtime ring current index Dst

Directory of Open Access Journals (Sweden)

G. Rostoker

Full Text Available There has been some discussion in recent times regarding whether or not substorm expansive phase activity plays any role of importance in the formation of the stormtime ring current. I explore this question using the Kp index as a proxy for substorm expansive phase activity and the Dst index as a proxy for symmetric ring current strength. I find that increases in Dst are mildly related to the strength of substorm expansive phase activity during the development of the storm main phase. More surprisingly, I find that the strength of Dst during the storm recovery phase is positively correlated with the strength of substorm expansive phase activity. This result has an important bearing on the question of how much the Dst index reflects activity other than that of the stormtime symmetric ring current strength for which it is supposed to be a proxy.Key words: Ionosphere (electric fields and currents - Magnetospheric physics (current systems; storms and substorms

Effects of substorms on the stormtime ring current index Dst

Directory of Open Access Journals (Sweden)

G. Rostoker

2000-11-01

Full Text Available There has been some discussion in recent times regarding whether or not substorm expansive phase activity plays any role of importance in the formation of the stormtime ring current. I explore this question using the Kp index as a proxy for substorm expansive phase activity and the Dst index as a proxy for symmetric ring current strength. I find that increases in Dst are mildly related to the strength of substorm expansive phase activity during the development of the storm main phase. More surprisingly, I find that the strength of Dst during the storm recovery phase is positively correlated with the strength of substorm expansive phase activity. This result has an important bearing on the question of how much the Dst index reflects activity other than that of the stormtime symmetric ring current strength for which it is supposed to be a proxy.Key words: Ionosphere (electric fields and currents - Magnetospheric physics (current systems; storms and substorms

Ring Current Response to Different Storm Drivers. Van Allen Probes and Cluster Observations.

Science.gov (United States)

Bingham, S.; Mouikis, C.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

2015-12-01

The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), co-rotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure change the global magnetic field, which affects the transport of the radiation belts. In order to determine the field changes during a storm it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. The source population of the storm time ring current is the night side plasma sheet. However, it is not clear how these convecting particles affect the storm time ring current pressure development. We use Van Allen Probes and Cluster observations together with the Volland-Stern and dipole magnetic field models to determine the contribution in the ring current pressure of the plasma sheet particles convecting from the night side that are on open drift paths, during the storm evolution. We compare storms that are related to different interplanetary drivers, CME and CIR, as observed at different local times.

First current density measurements in the ring current region using simultaneous multi-spacecraft CLUSTER-FGM data

Directory of Open Access Journals (Sweden)

C. Vallat

2005-07-01

Full Text Available The inner magnetosphere's current mapping is one of the key elements for current loop closure inside the entire magnetosphere. A method for directly computing the current is the multi-spacecraft curlometer technique, which is based on the application of Maxwell-Ampère's law. This requires the use of four-point magnetic field high resolution measurements. The FGM experiment on board the four Cluster spacecraft allows, for the first time, an instantaneous calculation of the magnetic field gradients and thus a measurement of the local current density. This technique requires, however, a careful study concerning all the factors that can affect the accuracy of the J estimate, such as the tetrahedral geometry of the four spacecraft, or the size and orientation of the current structure sampled. The first part of this paper is thus providing a detailed analysis of the method accuracy, and points out the limitations of this technique in the region of interest. The second part is an analysis of the ring current region, which reveals, for the first time, the large latitudinal extent of the ring current, for all magnetic activity levels, as well as the latitudinal evolution of the perpendicular (and parallel components of the current along the diffuse auroral zone. Our analysis also points out the sharp transition between two distinct plasma regions, with the existence of high diamagnetic currents at the interface, as well as the filamentation of the current inside the inner plasma sheet. A statistical study over multiple perigee passes of Cluster (at about 4 R_E from the Earth reveals the azimuthal extent of the partial ring current. It also reveals that, at these distances and all along the evening sector, there isn't necessarily a strong dependence of the local current density value on the magnetic activity level. This is a direct consequence of the ring current morphology evolution, as well as the relative

Storage Rings

International Nuclear Information System (INIS)

Fischer, W.

2010-01-01

Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10 -6 eV to 3.5 x 10 12 eV (LHC, 7 x 10 12 eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or positron beams

Effects of the Ring Current on ULF Waves in the Magnetosphere

Directory of Open Access Journals (Sweden)

Khan-Hyuk Kim

1994-06-01

Full Text Available A three-dimensional box model has been developed to study the MHD wave coupling in the magnetosphere. In this model, the effects of the ring current are included by assuming the pressure gradients in the MHD equations. It is found that the axisymmetric ring current may play an important role in producing spectral noises in compressional waves, while field line resonances have no such disturbances. These results may explain the current observational characteristics that compressional cavity modes hardly appear in the satellite experiment, while field line resonances often occur. Our numerical results also suggest that any discrete spectral peaks such as the global cavity modes can hardly occur where the pressure distribution of the ring current becomes important. The continuous band of transverse waves is found to be unperturbed until the ring current becomes significantly asymmetric with respect to the dipole axis. In addition, our results in the absence of the pressure gradient are found to be consistent with the previous results from the box-like and dipole models.

Status of the experimental studies of the electron cloud at the Los Alamos proton storage ring

International Nuclear Information System (INIS)

Macek, R.J.; Browman, A.A.; Borden, M.J.; Fitzgerald, D.H.; McCrady, R.C.; Spickermann, T.J.; Zaugg, T.J.

2003-01-01

The electron cloud (EC) at the Los Alamos Proton Storage Ring (PSR) has been studied extensively for the past several years with an overall aim to identify and measure its important characteristics, the factors that influence these characteristics, and to relate these to the two-stream (e-p) transverse instability long observed at PSR. Some new results since PAC2001 are presented.

Progress On Neutrino-Proton Neutral-Current Scattering In MicroBooNE

Energy Technology Data Exchange (ETDEWEB)

Pate, Stephen [New Mexico State U.

2017-01-16

The MicroBooNE Experiment at the Fermi National Accelerator Laboratory, an 89-ton active mass liquid argon time projection chamber, affords a unique opportunity to observe low-$Q^2$ neutral-current neutrino-proton scattering events. Neutral-current neutrino-proton scattering at $Q^2 < 1$ GeV$^2$ is dominated by the proton's axial form factor, which can be written as a combination of contributions from the up, down, and strange quarks: $G_A(Q^2) = \\frac{1}{2}[-G_A^u(Q^2)+G_A^d(Q^2)+G_A^s(Q^2)]$. The contribution from up and down quarks has been established in past charged-current measurements. The contribution from strange quarks at low $Q^2$ remains unmeasured; this is of great interest since the strange quark contribution to the proton spin can be determined from the low-$Q^2$ behavior: $\\Delta S = G_A^s(Q^2=0)$. MicroBooNE began operating in the Booster Neutrino Beam in October 2015. I will present the status in observing isolated proton tracks in the MicroBooNE detector as a signature for neutral-current neutrino-proton events. The sensitivity of the MicroBooNE experiment for measuring the strange quark contribution to the proton spin will be discussed.

Localized persistent spin currents in defect-free quasiperiodic rings with Aharonov–Casher effect

International Nuclear Information System (INIS)

Qiu, R.Z.; Chen, C.H.; Cheng, Y.H.; Hsueh, W.J.

2015-01-01

We propose strongly localized persistent spin current in one-dimensional defect-free quasiperiodic Thue–Morse rings with Aharonov–Casher effect. The results show that the characteristics of these localized persistent currents depend not only on the radius filling factor, but also on the strength of the spin–orbit interaction. The maximum persistent spin currents in systems always appear in the ring near the middle position of the system array whether or not the Thue–Morse rings array is symmetrical. The magnitude of the persistent currents is proportional to the sharpness of the resonance peak, which is dependent on the bandwidth of the allowed band in the band structure. The maximum persistent spin currents also increase exponentially as the generation order of the system increases. - Highlights: • Strongly localized persistent spin current in quasiperiodic AC rings is proposed. • Localized persistent spin currents are much larger than those produced by traditional mesoscopic rings. • Characteristics of the localized persistent currents depend on the radius filling factor and SOI strength. • The maximum persistent current increases exponentially with the system order. • The magnitude of the persistent currents is related to the sharpness of the resonance

The beam slow extraction from a magnetic ring of Moscow meson facility

International Nuclear Information System (INIS)

Gusev, O.A.; Malitsky, N.D.; Severgin, Yu.P.; Titov, V.A.; Shukeilo, I.A.; Aseev, V.N.; Grachev, M.I.; Lobashev, V.M.; Ostroumov, P.N.; Ponomaryov, O.V.

1990-01-01

The beam slow extraction from the circular accelerators or stretcher rings is generally realized by the resonant excitation of betratron oscillations. A precise betatron frequency control is proved to be quite necessary for high-efficient slow ejection. The Coulomb field turns out to have a significant influence upon the slow extraction from the high-current medium energy proton storage rings. It prevents resonant excitation at a reasonable rate and reduces the ejection efficiency. The proton storage ring of Moscow meson facility is an example of a stretcher with a noticeable beam space charge. The detailed investigation of the resonant ejection, having been performed for our stretcher, resulted in the conclusion that extracted beam average current should be limited by the value of 50 mA, which is only 10% of the linac design current. The search for the alternative version to the resonant ejection made us to analyze in details and to develop an old-fashioned method, based on the radial betatron oscillation excitation while the beam is being gradually shifted onto the thin target. (author) 5 refs., 4 figs

NRL ion ring program

International Nuclear Information System (INIS)

Kapetanakos, C.A.; Golden, J.; Drobot, A.; Mahaffey, R.A.; Marsh, S.J.; Pasour, J.A.

1977-01-01

An experiment is under way to form a storng proton ring using the 200 ka, 1.2 MeV, 50 nsec hollow proton beam recently generated at NRL. The 5 m long magnetic field configuration consists of a magnetic cusp, a compressing magnetic field, a gate field and a magnetic mirror. The midplane value of the magnetic mirror is such that the major radius of the ring will be about 10 cm. The degree of field reversal that will be achieved with 5 x 10 16 protons per pulse from the existing beam depends upon the field reversal is possible with the 600 kA proton beam that would be generated from the low inductance coaxial triode coupled to the upgraded Gamble II generator. The propagation and trapping of an intense proton beam in the experimental magnetic field configuration is investigated numerically. The results show that the self magnetic has a very pronounced effect on the dynamics of the gyrating protons

ULF waves associated with enhanced subauroral proton precipitation

Science.gov (United States)

Immel, Thomas J.; Mende, S. B.; Frey, H. U.; Patel, J.; Bonnell, J. W.; Engebretson, M. J.; Fuselier, S. A.

Several types of sub-auroral proton precipitation events have been identified using the Spectrographic Imager (SI) onboard the NASA-IMAGE satellite, including dayside subauroral proton flashes and detached proton arcs in the dusk sector. These have been observed at various levels of geomagnetic activity and solar wind conditions and the mechanism driving the precipitation has often been assumed to be scattering of protons into the loss cone by enhancement of ion-cyclotron waves in the interaction of the thermal plasmaspheric populations and more energetic ring current particles. Indeed, recent investigation of the detached arcs using the MPA instruments aboard the LANL geosynchronous satellites has shown there are nearly always heightened densities of cold plasma on high-altitude field lines which map down directly to the sub-auroral precipitation. If the ion-cyclotron instability is a causative mechanism, the enhancement of wave activity at ion-cyclotron frequencies should be measurable. It is here reported that magnetic pulsations in the Pc1 range occur in the vicinity of each of 4 detached arcs observed in 2000-2002, though with widely varying signatures. Additionally, longer period pulsations in the Pc5 ranges are also observed in the vicinity of the arcs, leading to the conclusion that a bounce-resonance of ring-current protons with the azimuthal Pc5 wave structure may also contribute to the detached precipitation.

Design summary of the magnet support structures for the proton storage ring injection line upgrade

International Nuclear Information System (INIS)

Bernardin, J.D.; Ledford, J.E.; Smith, B.G.

1997-05-01

This report summarizes the technical engineering and design issues associated with the Proton Storage Ring (PSR) Injection Line upgrade of the Los Alamos Neutron Science Center (LANSCE). The main focus is on the engineering design calculations of several magnet support structures. The general procedure based upon a set number of design criteria is outlined, followed by a case-by-case summary of the engineering design analyses, reutilization or fabrication callouts and design safety factors

The plasmasheet H+ and O+ contribution on the storm time ring current

Science.gov (United States)

Mouikis, C.; Bingham, S.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

2015-12-01

The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes and Cluster observations to determine the contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. Using the Volland-Stern model with a dipole magnetic field together with the identification of the observed energy cutoffs in the particle spectra, we specify the pressure contributed by H+ and O+ populations that are on open drift paths vs. the pressure contributed by the trapped populations, for different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L~2 and their pressure compares to the local magnetic field pressure as deep as L~3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current.

Link between EMIC waves in a plasmaspheric plume and a detached sub-auroral proton arc with observations of Cluster and IMAGE satellites

Science.gov (United States)

Yuan, Zhigang; Deng, Xiaohua; Lin, Xi; Pang, Ye; Zhou, Meng; Décréau, P. M. E.; Trotignon, J. G.; Lucek, E.; Frey, H. U.; Wang, Jingfang

2010-04-01

In this paper, we report observations from a Cluster satellite showing that ULF wave occurred in the outer boundary of a plasmaspheric plume on September 4, 2005. The band of observed ULF waves is between the He+ ion gyrofrequency and O+ ion gyrofrequency at the equatorial plane, implying that those ULF waves can be identified as EMIC waves generated by ring current ions in the equatorial plane and strongly affected by rich cold He+ ions in plasmaspheric plumes. During the interval of observed EMIC waves, the footprint of Cluster SC3 lies in a subauroral proton arc observed by the IMAGE FUV instrument, demonstrating that the subauroral proton arc was caused by energetic ring current protons scattered into the loss cone under the Ring Current (RC)-EMIC interaction in the plasmaspheric plume. Therefore, the paper provides a direct proof that EMIC waves can be generated in the plasmaspheric plume and scatter RC ions to cause subauroral proton arcs.

Golden Jubilee photos: ISR - The first proton-proton interactions

CERN Document Server

2004-01-01

At the inauguration ceremony for the Intersecting Storage Rings (ISR) on 16 October 1971, the man in charge of their construction, Kjell Johnsen, presented the "key" to the machine to Edoardo Amaldi, President of Council. Seated on the stage with them for this symbolic event were Victor Weisskopf, Marcel Antonioz, Willy Jentschke (seen on the left of the photo) and Werner Heisenberg (on the far right). On 27 January that year, in a world premier, signals produced by proton-proton collisions had been observed at the ISR. The protons, supplied by the PS, were injected into two identical rings, each measuring 300 metres in diameter, and collided head on at the 8 points where the rings intersected. The installation, which remained in operation until 1984, gave physicists access to a wide range of energies for hadron physics, hitherto restricted to the data from cosmic ray studies. The many technological challenges that were met at the ISR, in the fields of vacuum technology and stochastic cooling for instance,...

FIRST POLARIZED PROTON COLLISIONS AT RHIC

International Nuclear Information System (INIS)

ROSER, T.; AHRENS, L.; ALESSI, J.; BAI, M.; BEEBE-WANG, J.; BRENNAN, J.M.; BROWN, K.A.; BUNCE, G.; CAMERON, P.; COURANT, E.D.; DREES, A.; FISCHER, W.; FLILLER, R. III; GLENN, W.; HUANG, H.; LUCCIO, A.U.; MACKAY, W.W.; MAKDISI, Y.; MONTAG, C.; PILAT, F.; PTITSYN, V.; SATOGATA, T.

2002-01-01

We successfully injected polarized protons in both RHIC rings and maintained polarization during acceleration up to 100 GeV per ring using two Siberian snakes in each ring. Each snake consists of four helical superconducting dipoles which rotate the polarization by 180 o about a horizontal axis. This is the first time that polarized protons have been accelerated to 100 GeV

Development of high intensity proton accelerator

International Nuclear Information System (INIS)

Mizumoto, M.; Kusano, J.; Hasegawa, K.; Ouchi, N.; Oguri, H.; Kinsho, M.; Touchi, Y.; Honda, Y.; Mukugi, K.; Ino, H.; Noda, F.; Akaoka, N.; Kaneko, H.; Chishiro, E.; Fechner, B.

1997-01-01

The high-intensity proton linear accelerator with an energy of 1.5 GeV and an average current of 5.33mA has been proposed for the Neutron Science Project (NSP) at JAERI. the NSP is aiming at exploring nuclear technologies for nuclear waste transmutation based on a proton induced spallation neutrons. The proposed accelerators facilities will be also used in the various basic research fields such as condensed matter physics in combination with a high intensity proton storage ring. The R and D work has been carried out for the components of the front-end of the proton accelerator. For the high energy portion above 100 MeV, superconducting (SC) accelerator linac has been designed and developed as a major option. (Author) 7 refs

Dextromethorphan inhibition of voltage-gated proton currents in BV2 microglial cells.

Science.gov (United States)

Song, Jin-Ho; Yeh, Jay Z

2012-05-10

Dextromethorphan, an antitussive drug, has a neuroprotective property as evidenced by its inhibition of microglial production of pro-inflammatory cytokines and reactive oxygen species. The microglial activation requires NADPH oxidase activity, which is sustained by voltage-gated proton channels in microglia as they dissipate an intracellular acid buildup. In the present study, we examined the effect of dextromethorphan on proton currents in microglial BV2 cells. Dextromethorphan reversibly inhibited proton currents with an IC(50) value of 51.7 μM at an intracellular/extracellular pH gradient of 5.5/7.3. Dextromethorphan did not change the reversal potential or the voltage dependence of the gating. Dextrorphan and 3-hydroxymorphinan, major metabolites of dextromethorphan, and dextromethorphan methiodide were ineffective in inhibiting proton currents. The results indicate that dextromethorphan inhibition of proton currents would suppress NADPH oxidase activity and, eventually, microglial activation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Tinkering at the main-ring lattice

Energy Technology Data Exchange (ETDEWEB)

Ohnuma, S.

1982-08-23

To improve production of usable antiprotons using the proton beam from the main ring and the lossless injection of cooled antiprotons into the main ring, modifications of the main ring lattice are recommended.

Mitigation of the electron-cloud effect in the PSR and SNS proton storage rings by tailoring the bunch profile

International Nuclear Information System (INIS)

Pivi, M.; Furman, M.A.

2003-01-01

For the storage ring of the Spallation Neutron Source(SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electroncloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure

Direct-current proton-beam measurements at Los Alamos

International Nuclear Information System (INIS)

Sherman, J.; Stevens, R.R.; Schneider, J.D.; Zaugg, T.

1994-01-01

Recently, a CW proton accelerator complex was moved from Chalk River Laboratories (CRL) to Los Alamos National Laboratory. This includes a 50-keV dc proton injector with a single-solenoid low-energy beam transport system (LEBT) and a CW 1.25-MeV, 267-MHz radiofrequency quadrupole (RFQ). The move was completed after CRL had achieved 55-mA CW operation at 1.25 MeV using 250-kW klystrode tubes to power the RFQ. These accelerator components are prototypes for the front end of a CW linac required for an accelerator-driven transmutation linac, and they provide early confirmation of some CW accelerator components. The injector (ion source and LEBT) and emittance measuring unit are installed and operational at Los Alamos. The dc microwave ion source has been operated routinely at 50-keV, 75-mA hydrogen-ion current. This ion source has demonstrated very good discharge and H 2 gas efficiencies, and sufficient reliability to complete CW RFQ measurements at CRL. Proton fraction of 75% has been measured with 550-W discharge power. This high proton fraction removes the need for an analyzing magnet. Proton LEBT emittance measurements completed at Los Alamos suggest that improved transmission through the RFQ may be achieved by increasing the solenoid focusing current. Status of the final CW RFQ operation at CRL and the installation of the RFQ at Los Alamos is given

Highly Efficient Spin-Current Operation in a Cu Nano-Ring

Science.gov (United States)

Murphy, Benedict A.; Vick, Andrew J.; Samiepour, Marjan; Hirohata, Atsufumi

2016-11-01

An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic.

A novel method for the biosynthesis of deuterated proteins with selective protonation at the aromatic rings of Phe, Tyr and Trp

International Nuclear Information System (INIS)

Rajesh, Sundaresan; Nietlispach, Daniel; Nakayama, Hiroshi; Takio, Koji; Laue, Ernest D.; Shibata, Takehiko; Ito, Yutaka

2003-01-01

A novel biosynthetic strategy is described for the preparation of deuterated proteins containing protons at the ring carbons of Phe, Tyr and Trp, using the aromatic amino acid precursor shikimic acid. Specific protonation at aromatic side chains, with complete deuteration at C α/β positions was achieved in proteins overexpressed in bacteria grown in shikimate-supplemented D 2 O medium. Co-expression of a shikimate transporter in prototrophic bacteria resulted in protonation levels of 62-79%, whereas complete labeling was accomplished using shikimate auxotrophic bacteria. Our labeling protocol permits the measurement of important aromatic side chain derived distance restraints in perdeuterated proteins that could be utilized to enhance the accuracy of NMR structures calculated using low densities of NOEs from methyl selectively protonated samples

New Way of Characterizing the State of the Ring Current

Science.gov (United States)

Wolf, R.; Bao, S.; Gkioulidou, M.; Yang, J.; Toffoletto, F.

2017-12-01

The flux tube entropy S is invariant in ideal MHD and is a good way to characterize the degree to which a closed flux tube is loaded with particle energy. Flux tube entropy generally increases with increasing geocentric distance. A flux tube that is injected from the plasma sheet into the ring current tends to be a bubble that has a lower S value than typical plasma sheet flux tubes, and it tends to penetrate to a position where the surroundings matches its S. From this point of view, a good way to characterize the state of the ring current is through the function dF/dS, which specifies how much magnetic flux is occupied by tubes with different degrees of loading. By displaying dF/dS curves before and during storm main phases simulated with the RCM-E code, we determine that, in the model, the injection of the stormtime ring current consists of replacing pre-storm low-S flux tubes with tubes from the plasma sheet that have a certain limited range of S, which is well below typical plasma-sheet values. We also display dF/dS curves for passes by the Van Allen Probes before and during storm main phases, and compare with the RCM-E-derived curves, to gain insight into the nature of the flux tubes that are injected to form the real storm-time ring current.

Antipsychotics, chlorpromazine and haloperidol inhibit voltage-gated proton currents in BV2 microglial cells.

Science.gov (United States)

Shin, Hyewon; Song, Jin-Ho

2014-09-05

Microglial dysfunction and neuroinflammation are thought to contribute to the pathogenesis of schizophrenia. Some antipsychotic drugs have anti-inflammatory activity and can reduce the secretion of pro-inflammatory cytokines and reactive oxygen species from activated microglial cells. Voltage-gated proton channels on the microglial cells participate in the generation of reactive oxygen species and neuronal toxicity by supporting NADPH oxidase activity. In the present study, we examined the effects of two typical antipsychotics, chlorpromazine and haloperidol, on proton currents in microglial BV2 cells using the whole-cell patch clamp method. Chlorpromazine and haloperidol potently inhibited proton currents with IC50 values of 2.2 μM and 8.4 μM, respectively. Chlorpromazine and haloperidol are weak bases that can increase the intracellular pH, whereby they reduce the proton gradient and affect channel gating. Although the drugs caused a marginal positive shift of the activation voltage, they did not change the reversal potential. This suggested that proton current inhibition was not due to an alteration of the intracellular pH. Chlorpromazine and haloperidol are strong blockers of dopamine receptors. While dopamine itself did not affect proton currents, it also did not alter proton current inhibition by the two antipsychotics, indicating dopamine receptors are not likely to mediate the proton current inhibition. Given that proton channels are important for the production of reactive oxygen species and possibly pro-inflammatory cytokines, the anti-inflammatory and antipsychotic activities of chlorpromazine and haloperidol may be partly derived from their ability to inhibit microglial proton currents. Copyright © 2014 Elsevier B.V. All rights reserved.

Resonant beam behavior studies in the Proton Storage Ring

Directory of Open Access Journals (Sweden)

S. Cousineau

2003-07-01

Full Text Available We present studies of space-charge-induced beam profile broadening at high intensities in the Proton Storage Ring (PSR at Los Alamos National Laboratory. We investigate the profile broadening through detailed particle-in-cell simulations of several experiments and obtain results in good agreement with the measurements. We interpret these results within the framework of coherent resonance theory. With increasing intensity, our simulations show strong evidence for the presence of a quadrupole-mode resonance of the beam envelope with the lattice in the vertical plane. Specifically, we observe incoherent tunes crossing integer values, and large amplitude, nearly periodic envelope oscillations. At the highest operating intensities, we observe a continuing relaxation of the beam through space charge forces leading to emittance growth. The increase of emittance commences when the beam parameters encounter an envelope stop band. Once the stop band is reached, the emittance growth balances the intensity increase to maintain the beam near the stop band edge. Additionally, we investigate the potential benefit of a stop band correction to the high intensity PSR beam.

Requirements of data acquisition and analysis for condensed matter studies at the weapons neutron research/proton storage ring facility

International Nuclear Information System (INIS)

Johnson, M.W.; Goldstone, J.A.; Taylor, A.D.

1982-11-01

With the completion of the proton storage ring (PSR) in 1985, the subsquent increase in neutron flux, and the continuing improvement in neutron scattering instruments, a significant improvement in data acquisition and data analysis capabilities will be required. A brief account of the neutron source is given together with the associated neutron scattering instruments. Based on current technology and operating instruments, a projection for 1985 to 1990 of the neutron scattering instruments and their main parameters are given. From the expected data rates and the projected instruments, the size of data storage is estimated and the user requirements are developed. General requirements are outlined with specific requirements in user hardware and software stated. A project time scale to complete the data acquisition and analysis system by 1985 is given

Electric currents induced by twisted light in Quantum Rings.

Science.gov (United States)

Quinteiro, G F; Berakdar, J

2009-10-26

We theoretically investigate the generation of electric currents in quantum rings resulting from the optical excitation with twisted light. Our model describes the kinetics of electrons in a two-band model of a semiconductor-based mesoscopic quantum ring coupled to light having orbital angular momentum (twisted light). We find the analytical solution, which exhibits a "circular" photon-drag effect and an induced magnetization, suggesting that this system is the circular analog of that of a bulk semiconductor excited by plane waves. For realistic values of the electric field and material parameters, the computed electric current can be as large as microA; from an applied perspective, this opens new possibilities to the optical control of the magnetization in semiconductors.

Independent component analysis applied to long bunch beams in the Los Alamos Proton Storage Ring

Science.gov (United States)

Kolski, Jeffrey S.; Macek, Robert J.; McCrady, Rodney C.; Pang, Xiaoying

2012-11-01

Independent component analysis (ICA) is a powerful blind source separation (BSS) method. Compared to the typical BSS method, principal component analysis, ICA is more robust to noise, coupling, and nonlinearity. The conventional ICA application to turn-by-turn position data from multiple beam position monitors (BPMs) yields information about cross-BPM correlations. With this scheme, multi-BPM ICA has been used to measure the transverse betatron phase and amplitude functions, dispersion function, linear coupling, sextupole strength, and nonlinear beam dynamics. We apply ICA in a new way to slices along the bunch revealing correlations of particle motion within the beam bunch. We digitize beam signals of the long bunch at the Los Alamos Proton Storage Ring with a single device (BPM or fast current monitor) for an entire injection-extraction cycle. ICA of the digitized beam signals results in source signals, which we identify to describe varying betatron motion along the bunch, locations of transverse resonances along the bunch, measurement noise, characteristic frequencies of the digitizing oscilloscopes, and longitudinal beam structure.

Independent component analysis applied to long bunch beams in the Los Alamos Proton Storage Ring

Directory of Open Access Journals (Sweden)

Jeffrey S. Kolski

2012-11-01

Full Text Available Independent component analysis (ICA is a powerful blind source separation (BSS method. Compared to the typical BSS method, principal component analysis, ICA is more robust to noise, coupling, and nonlinearity. The conventional ICA application to turn-by-turn position data from multiple beam position monitors (BPMs yields information about cross-BPM correlations. With this scheme, multi-BPM ICA has been used to measure the transverse betatron phase and amplitude functions, dispersion function, linear coupling, sextupole strength, and nonlinear beam dynamics. We apply ICA in a new way to slices along the bunch revealing correlations of particle motion within the beam bunch. We digitize beam signals of the long bunch at the Los Alamos Proton Storage Ring with a single device (BPM or fast current monitor for an entire injection-extraction cycle. ICA of the digitized beam signals results in source signals, which we identify to describe varying betatron motion along the bunch, locations of transverse resonances along the bunch, measurement noise, characteristic frequencies of the digitizing oscilloscopes, and longitudinal beam structure.

A renormalization group study of persistent current in a quasiperiodic ring

Energy Technology Data Exchange (ETDEWEB)

Dutta, Paramita [Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Sector-I, Block-AF, Bidhannagar, Kolkata-700 064 (India); Maiti, Santanu K., E-mail: santanu.maiti@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata-700 108 (India); Karmakar, S.N. [Theoretical Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Sector-I, Block-AF, Bidhannagar, Kolkata-700 064 (India)

2014-04-01

We propose a real-space renormalization group approach for evaluating persistent current in a multi-channel quasiperiodic Fibonacci tight-binding ring based on a Green's function formalism. Unlike the traditional methods, the present scheme provides a powerful tool for the theoretical description of persistent current with a very high degree of accuracy in large periodic and quasiperiodic rings, even in the micron scale range, which emphasizes the merit of this work.

Plasma confinement in a magnetic field of the internal ring current

International Nuclear Information System (INIS)

Shafranov, Vitaly; Popovich, Paul; Samitov, Marat

2000-01-01

Plasma confinement in compact region surrounding an internal ring current is considered. As the limiting case of large aspect ratio system the cylindrical plasma is considered initially. Analysis of the cylindrical tubular plasma equilibrium and stability against the most dangerous flute (m=0) and kink (m=1) modes revealed the possibility of the MHD stable plasma confined by magnetic field of the internal rod current, with rather peaked plasma pressure and maximal local beta β(γ)=0.4. In case of the toroidal internal ring system an additional external magnetic field creates the boundary separatrix witch limits the plasma volume. The dependence of the plasma pressure profiles, marginally stable with respect to the flute modes, from the shape of the external plasma boundary (separatrix) in such kind closed toroidal systems is investigated. The internal ring system with circular poloidal magnetic mirror, where the ring supports could be placed, is proposed. (author)

Geomagnetic storms, the Dst ring-current myth and lognormal distributions

Science.gov (United States)

Campbell, W.H.

1996-01-01

The definition of geomagnetic storms dates back to the turn of the century when researchers recognized the unique shape of the H-component field change upon averaging storms recorded at low latitude observatories. A generally accepted modeling of the storm field sources as a magnetospheric ring current was settled about 30 years ago at the start of space exploration and the discovery of the Van Allen belt of particles encircling the Earth. The Dst global 'ring-current' index of geomagnetic disturbances, formulated in that period, is still taken to be the definitive representation for geomagnetic storms. Dst indices, or data from many world observatories processed in a fashion paralleling the index, are used widely by researchers relying on the assumption of such a magnetospheric current-ring depiction. Recent in situ measurements by satellites passing through the ring-current region and computations with disturbed magnetosphere models show that the Dst storm is not solely a main-phase to decay-phase, growth to disintegration, of a massive current encircling the Earth. Although a ring current certainly exists during a storm, there are many other field contributions at the middle-and low-latitude observatories that are summed to show the 'storm' characteristic behavior in Dst at these observatories. One characteristic of the storm field form at middle and low latitudes is that Dst exhibits a lognormal distribution shape when plotted as the hourly value amplitude in each time range. Such distributions, common in nature, arise when there are many contributors to a measurement or when the measurement is a result of a connected series of statistical processes. The amplitude-time displays of Dst are thought to occur because the many time-series processes that are added to form Dst all have their own characteristic distribution in time. By transforming the Dst time display into the equivalent normal distribution, it is shown that a storm recovery can be predicted with

ISABELLE: a proposal for construction of a proton--proton storage accelerator facility

International Nuclear Information System (INIS)

1976-05-01

The construction of an Intersecting Storage Accelerator Facility (ISA or ISABELLE) at Brookhaven National Laboratory is proposed. ISABELLE will permit the exploration of proton-proton collisions at center-of-mass energies continuously variable from 60 to 400 GeV and with luminosities of 10 32 to 10 33 cm -2 sec -1 over the entire range. An overview of the physics potential of this machine is given, covering the production of charged and neutral intermediate vector bosons, the hadron production at high transverse momentum, searches for new, massive particles, and the energy dependence of the strong interactions. The facility consists of two interlaced rings of superconducting magnets in a common tunnel about 3 km in circumference. The proton beams will collide at eight intersection regions where particle detectors will be arranged for studying the collision processes. Protons of approximately 30 GeV from the AGS will be accumulated to obtain the design current of 10A prior to acceleration to final energy. The design and performance of existing full-size superconducting dipoles and quadrupoles is described. The conceptual design of the accelerator systems and the conventional structures and buildings is presented. A preliminary cost estimate and construction schedule are given. Possible future options such as proton-antiproton, proton-deuteron and electron-proton collisions are discussed

WE-D-BRB-03: Current State of Volumetric Image Guidance for Proton Therapy

Energy Technology Data Exchange (ETDEWEB)

Hua, C. [St. Jude Children’s Research Hospital (United States)

2016-06-15

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy. B. Teo, B.K Teo had received travel funds from IBA in 2015.

WE-D-BRB-03: Current State of Volumetric Image Guidance for Proton Therapy

International Nuclear Information System (INIS)

Hua, C.

2016-01-01

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy. Learning Objectives: Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy. The current state of volumetric image guidance equipment in proton therapy. Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy. B. Teo, B.K Teo had received travel funds from IBA in 2015.

Ring current shifts in {sup 19}F-NMR of membrane proteins

Energy Technology Data Exchange (ETDEWEB)

Liu, Dongsheng, E-mail: liudsh@shanghaitech.edu.cn; Wüthrich, Kurt, E-mail: kwuthrich@shanghaitech.edu.cn [ShanghaiTech University, iHuman Institute (China)

2016-05-15

Fluorine-19 NMR markers are attractive reporter groups for use in studies of complex biomacromolecular systems, in particular also for studies of function-related conformational equilibria and rate processes in membrane proteins. Advantages of {sup 19}F-NMR probes include high sensitivity of the {sup 19}F chemical shifts to variations in the non-covalent environment. Nonetheless, in studies of G protein-coupled receptors (GPCR) we encountered situations where {sup 19}F chemical shifts were not responsive to conformational changes that had been implicated by other methods. This prompted us to examine possible effects of aromatic ring current fields on the chemical shifts of {sup 19}F-NMR probes used in GPCRs. Analysis of previously reported {sup 19}F-NMR data on the β{sub 2}-adrenergic receptor and mammalian rhodopsin showed that all {sup 19}F-labeling sites which manifested conformational changes are located near aromatic residues. Although ring current effects are small when compared to other known non-covalent effects on {sup 19}F chemical shifts, there is thus an indication that their contributions are significant when studying activation processes in GPCRs, since the observed activation-related {sup 19}F-NMR chemical shifts are comparable in size to the calculated ring current shifts. Considering the impact of ring current shifts may thus be helpful in identifying promising indigenous or engineered labeling sites for future {sup 19}F-NMR studies of GPCR activation, and novel information may be obtained on the nature of conformational rearrangements near the {sup 19}F-labels. It will then also be interesting to see if the presently indicated role of ring current shifts in membrane protein studies with {sup 19}F-NMR markers can be substantiated by a more extensive data base resulting from future studies.

Mapping return currents in laser-generated Z-pinch plasmas using proton deflectometry

International Nuclear Information System (INIS)

Manuel, M. J.-E.; Sinenian, N.; Seguin, F. H.; Li, C. K.; Frenje, J. A.; Rinderknecht, H. G.; Casey, D. T.; Zylstra, A. B.; Petrasso, R. D.; Beg, F. N.

2012-01-01

Dynamic return currents and electromagnetic field structure in laser-generated Z-pinch plasmas have been measured using proton deflectometry. Experiments were modeled to accurately interpret deflections observed in proton radiographs. Current flow is shown to begin on axis and migrate outwards with the expanding coronal plasma. Magnetic field strengths of ∼1 T are generated by currents that increase from ∼2 kA to ∼7 kA over the course of the laser pulse. Proton deflectometry has been demonstrated to be a practical alternative to other magnetic field diagnostics for these types of plasmas.

On the magnetic effect of the quiet ring current

International Nuclear Information System (INIS)

Feldstein, Ya.I.; Porchkhidze, Ts.D.

1983-01-01

Magnetic effects of the quiet ring current DRsu (q) along the geomagnetic equator near a minimUm of solar activity are considered. The division of Dsub(st)-variation of the geomagnetic field observed on the Earth's surface into DCF and DR components for January 23-24, 1974 has been carried out. DRsup(q) being 16.7 nT. A comparison with the magnetic field of the ring current and the energy particles moving round the Earth in the radiation zone shows a good agreement in the intensities obtained by two methods. This means that in calculating the Dsub(st)-index the values of the H-component of the field are taken as a bench mark during such time intervals when the DRsup(q) field is approximately compensated by the fields of currents on the magnetopause DCFsup(q). The estimates giVe RCsup(q) approximately - 12 nT

Temperature dependence of (+)-catechin pyran ring proton coupling constants as measured by NMR and modeled using GMMX search methodology

Science.gov (United States)

Fred L. Tobiason; Stephen S. Kelley; M. Mark Midland; Richard W. Hemingway

1997-01-01

The pyran ring proton coupling constants for (+)-catechin have been experimentally determined in deuterated methanol over a temperature range of 213 K to 313 K. The experimental coupling constants were simulated to 0.04 Hz on the average at a 90 percent confidence limit using a LAOCOON method. The temperature dependence of the coupling constants was reproduced from the...

A novel method of flat YBCO rings development for shield-type superconducting fault current limiters fabrication

International Nuclear Information System (INIS)

Hekmati, Arsalan; Hosseini, Mehdi; Vakilian, Mehdi; Fardmanesh, Mehdi

2012-01-01

A method has been proposed for flat YBCO ring Fabrication. A prototype SFCL with proposed design has been fabricated using the rings. J c characteristics of the rings are measured using an innovative method. The application of flat superconductor rings has been investigated in the structure of inductive shield-type high temperature superconducting fault current limiters, HT c -SFCL. A laboratory scale inductive shield-type HT c -SFCL has been designed and fabricated using flat superconductor rings. The fabrication process has been fully presented. YBCO powder has been used for the fabrication of superconductor rings. This fabrication process, being quite innovative, is introduced completely. The method of the trapped field measurement has been used for the critical current density measurement of the fabricated superconductor rings. The device with nominal current of 2 A was tested in a 30 V circuit. The SFCL successfully limited the fault currents of up to 10 times the nominal current to an approximately fixed value of 3 A. The voltage-current characteristic of the fabricated prototype has also been obtained and has shown compatibility with the fault current limitation results.

DESY: Handling persistent eddy currents

International Nuclear Information System (INIS)

Anon.

1990-01-01

The vanishing electrical resistance of superconducting coils as well as their ability to provide magnetic fields far beyond those of saturated iron is the main motivation behind the push to use superconducting technology in big new proton accelerators. But this advantage can turn into a drawback at low excitations when the eddy currents - induced in any electromagnet when the field is changed - do not decay, but continue to flow. Preparations for the proton ring of the HERA electron-proton collider nearing completion at the German DESY Laboratory in Hamburg have borne this in mind

DESY: Handling persistent eddy currents

Energy Technology Data Exchange (ETDEWEB)

Anon.

1990-04-15

The vanishing electrical resistance of superconducting coils as well as their ability to provide magnetic fields far beyond those of saturated iron is the main motivation behind the push to use superconducting technology in big new proton accelerators. But this advantage can turn into a drawback at low excitations when the eddy currents - induced in any electromagnet when the field is changed - do not decay, but continue to flow. Preparations for the proton ring of the HERA electron-proton collider nearing completion at the German DESY Laboratory in Hamburg have borne this in mind.

Current density waves in open mesoscopic rings driven by time-periodic magnetic fluxes

International Nuclear Information System (INIS)

Yan Conghua; Wei Lianfu

2010-01-01

Quantum coherent transport through open mesoscopic Aharonov-Bohm rings (driven by static fluxes) have been studied extensively. Here, by using quantum waveguide theory and the Floquet theorem we investigate the quantum transport of electrons along an open mesoscopic ring threaded by a time-periodic magnetic flux. We predicate that current density waves could be excited along such an open ring. As a consequence, a net current could be generated along the lead with only one reservoir, if the lead additionally connects to such a normal-metal loop driven by the time-dependent flux. These phenomena could be explained by photon-assisted processes, due to the interaction between the transported electrons and the applied oscillating external fields. We also discuss how the time-average currents (along the ring and the lead) depend on the amplitude and frequency of the applied oscillating fluxes.

Photon-induced tunability of the thermospin current in a Rashba ring

Science.gov (United States)

Abdullah, Nzar Rauf; Arnold, Thorsten; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

2018-04-01

The goal of this work is to show how the thermospin polarization current in a quantum ring changes in the presence of Rashba spin-orbit coupling and a quantized single photon mode of a cavity the ring is placed in. Employing the reduced density operator and a general master equation formalism, we find that both the Rashba interaction and the photon field can significantly modulate the spin polarization and the thermospin polarization current. Tuning the Rashba coupling constant, degenerate energy levels are formed corresponding to the Aharonov-Casher destructive phase interference in the quantum ring system. Our analysis indicates that the maximum spin polarization can be observed at the points of degenerate energy levels due to spin accumulation in the system without the photon field. The thermospin current is thus suppressed. In the presence of the cavity, the photon field leads to an additional kinetic momentum of the electron. As a result the spin polarization can be enhanced by the photon field.

Modelling of the ring current in Saturn's magnetosphere

Directory of Open Access Journals (Sweden)

G. Giampieri

2004-01-01

Full Text Available The existence of a ring current inside Saturn's magnetosphere was first suggested by Smith et al. (1980 and Ness et al. (1981, 1982, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. Connerney et al. (1983 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set. First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects. Key words. Magnetospheric physics (current systems; planetary magnetospheres; plasma sheet

Beam position monitor multiplexer controller upgrade at the LAMPF proton storage ring

International Nuclear Information System (INIS)

Scarborough, W.K.; Cohen, S.

1992-01-01

The beam position monitor (BPM) is one of the primary diagnostic tools used for the tuning of the proton storage ring (PSR) at the Clinton P. Anderson Meson Physics Facility (LAMPF). A replacement for the existing, monolithic, wire-wrapped microprocessor-based BPM multiplexer controller has been built. The controller has been redesigned as a modular system retaining the same functionality of the original system built in 1981. Individual printed circuit cards are used for each controller function to insure greater maintainability and ease of keeping a spare parts inventory. Programmable logic device technology has substantially reduced the component count of the new controller. Diagnostic software was written to support the development of the upgraded controller. The new software actually uncovered some flaws in the original CAMAC interface. (author)

High current proton linear accelerators and nuclear power

International Nuclear Information System (INIS)

Tunnicliffe, P.R.; Chidley, B.G.; Fraser, J.S.

1976-01-01

This paper outlines a possible role that high-current proton linear accelerators might play as ''electrical breeders'' in the forthcoming nuclear-power economy. A high-power beam of intermediate energy protons delivered to an actinide-element target surrounded by a blanket of fertile material may produce fissile material at a competitive cost. Criteria for technical performance and, in a Canadian context, for costs are given and the major problem areas outlined not only for the accelerator and its associated rf power source but also for the target assembly. (author)

The current status of proton therapy in the world, the European Union and Slovakia

International Nuclear Information System (INIS)

Ruzicka, J.

2011-01-01

Proton therapy is considered to be very promising cancer treatment modality, and therefore many countries of the world are trying to (regardless of the high investment costs) to build their own atomic centre (or other proton centres if they operate already some). Proton therapy allows better control of therapeutic doses of radiation to which the patient is exposed. Proton irradiation of the tumor can kill more cancer cells while minimizing damage of healthy tissue. Currently there is about 33 facilities in operation in the world where proton therapy can be carried out. Proton therapy complex with new, highly sophisticated equipment is also being constructed in Slovakia - in The Central Military Hospital in Ruzomberok. The project is in its final stage of implementation. The paper describes the current status of proton therapy in the world, the European Union (EU) and Slovakia. In conclusion principally new Proton therapy unit complex built in Slovakia with similar facilities currently existing in EU countries (old 15 member states) is compared (especially from technical and medical aspects). (author)

Oscillatory persistent currents in self-assembled quantum rings

NARCIS (Netherlands)

Kleemans, N.A.J.M.; Bominaar-Silkens, I.M.A.; Fomin, V.; Gladilin, V.N.; Granados, D.; Taboada, A.G.; Garcia, J.M.; Offermans, P.; Zeitler, U.; Christianen, P.C.M.; Maan, J.C.; Devreese, J.T.; Koenraad, P.M.

2007-01-01

We report the direct measurement of the persistent current carried by a single electron by means of magnetization experiments on self-assembled InAs/GaAs quantum rings. We measured the first Aharonov-Bohm oscillation at a field of 14 T, in perfect agreement with our model based on the structural

The "g-2" Muon Storage Ring

CERN Multimedia

CERN PhotoLab

1974-01-01

The "g-2" muon storage ring, shortly before completion in June 1974. Bursts of pions (from a target, hit by a proton beam from the 26 GeV PS) are injected and polarized muons from their decay are captured on a stable orbit. When the muons decay too, their precession in the magnetic field of the storage ring causes a modulation of the decay-electron counting rate, from which the muon's anomalous magnetic moment can be determined. In 1977, the "g-2" magnets were modified to build ICE (Initial Cooling Experiment), a proton and antiproton storage ring for testing stochastic and electron cooling. Later on, the magnets had a 3rd life, when the ion storage ring CELSIUS was built from them in Uppsala. For later use as ICE, see 7711282, 7802099, 7809081,7908242.

Inter- and intra-annular proton exchange in gaseous benzylbenzenium ions (protonated diphenylmethane)

OpenAIRE

Kuck, Dietmar; Bäther, Wolfgang

1986-01-01

Two distinct proton exchange reactions occur in metastable gaseous benzylbenzenium ions, generated by isobutane chemical ionization of diphenylmethane and four deuterium-labelled analogues. Whereas the proton ring-walk at the benzenium moiety is fast giving rise to a completely random intraannular proton exchange, the interannular proton exchange is surprisingly slow and competes with the elimination of benzene. A kinetic isotope effect of kH/kD= 5 has been determined for the interannular pro...

Calculations of toroidal EXTRAP equilibria for different toroidal ring current configurations

International Nuclear Information System (INIS)

Drake, J.R.; Scheffel, J.

1985-12-01

EXTRAP is a concept in which a pure Z-pinch is generated along the axis of an octupole field. Experiments in a linear as well as in a sector geometry have demonstrated that the pinch becomes stable against instabilities for many Alfven times. The octupole field in EXTRAP is produced by four, external, current-carrying rings. In the toroidal geometry these rings must be supplemented by additional rings to compensate for the plasma loop force and transformer core leakage flux. Equilibrium studies are carried out for two basically ring designs. The studies are based on numerical equilibrium copmputations using the GOYA code. Sensitivity of the equilibrium to technical imperfections is also analyzed. (author)

Polarization Studies for the eRHIC Electron Storage Ring

Energy Technology Data Exchange (ETDEWEB)

Gianfelice-Wendt, Eliana [Fermilab; Tepikian, S. [Brookhaven

2018-04-01

A hadron/lepton collider with polarized beams has been under consideration by the scientific community since some years, in the U.S. and Europe. Among the various proposals, those by JLAB and BNL with polarized electron and proton beams are currently under closer study in the U.S. Experimenters call for the simultaneous storage of electron bunches with both spin helicity. In the BNL based Ring-Ring design, electrons are stored at top energy in a ring to be accommodated in the existing RHIC tunnel. The transversely polarized electron beam is injected into the storage ring at variable energies, between 5 and 18 GeV. Polarization is brought into the longitudinal direction at the IP by a couple of spin rotators. In this paper results of first studies of the attainable beam polarization level and lifetime in the storage ring at 18 GeV are presented.

Clinical application of proton magnetic resonance spectroscopy in differential diagnosis of intracranial lesions with ring-like enhancement

International Nuclear Information System (INIS)

Lai Ying; Cheng Kailiang; Zhang Mengchao; Liu Yunxia; Wang Wei

2009-01-01

Objective: To study the value of clinical application of 1 H proton magnetic resonance spectroscopy ( 1 H MRS) in the differential diagnosis of intracranial lesions with ring-like enhancement. Methods: 28 cases were diagnosed of intracranial lesions with ring-like enhancement by clinical examination and pathologic test. A total of 28 ratios cases included 6 cases high grade glioma, 10 cases of metastatic carcinoma (n=10) and 12 cases of brain abscess, after examined with 1HMRS, the ratios of various metabolites in focal center, enhancement ring,perifocal edema region and normal control group were detected and compared. Results: The ratios of NAA/Cho, Cho/Cr and NAA/Cr in focal center had no significantly differences between high grade glioma and metastatic carcinoma (P>0.05). The peak of NAA was significantly different between high grade glioma and metastatic carcinoma (P 0.05). The peak of AA was characteristic of brain abscess. The ratio of Cho/Cr 0 in brain abscess was significantly lower than those in high grade glioma and metastatic carcinoma (P 0 denoted the Cho content of contralateral normal brain region). These results accorded with the result of pathological examination. Conclusion: 1 HMRS can improve the diagnostic accuracy of intracranial lesions with ring-like enhancement. (authors)

Contradiction between the results of observations of resistance and critical current quantum oscillations in asymmetric superconducting rings

International Nuclear Information System (INIS)

Gurtovoi, V. L.; Dubonos, S. V.; Karpii, S. V.; Nikulov, A. V.; Tulin, V. A.

2007-01-01

Magnetic field dependences of critical current, resistance, and rectified voltage of asymmetric (half circles of different widths) and symmetrical (half circles of equal widths) aluminum rings close to the super-conducting transition were measured. All these dependences are periodic magnetic field functions with periods corresponding to the flux quantum in the ring. The periodic dependences of critical current measured in opposite directions were found to be close to each other for symmetrical rings and shifted with respect to each other by half the flux quantum in asymmetric rings with ratios between half circle widths of from 1.25 to 2. This shift of the dependences by a quarter of the flux quantum as the ring becomes asymmetric makes critical current anisotropic, which explains the effect of alternating current rectification observed for asymmetric rings. Shifts of the extrema of the periodic dependences of critical current by a quarter of the flux quantum directly contradict the results obtained by measuring asymmetric ring resistance oscillations, whose extrema are, as for symmetrical rings, observed at magnetic fluxes equal to an integer and a half of flux quanta

Accumulator ring design for the NSNS project

International Nuclear Information System (INIS)

Weng, W.T.; Alessi, J.; Beebe-Wang, J.

1997-01-01

The goal of the proposed National Spallation Neutron Source (NSNS) is to provide a short pulse proton beam of about 0.5 μs with average beam power of 1 MW. To achieve such purpose, a proton storage ring operated at 60 Hz with 1 x 10 14 protons per pulse at 1 GeV is required. The Accumulator Ring (AR) receives 1 msec long H - beam bunches of 28 mA from a 1 GeV linac. Scope and design performance goals of the AR are presented, other possible technological choices and design options considered, but not adopted, are also briefly reviewed

Plasma position from ring current measurements in Extrap T1

International Nuclear Information System (INIS)

Brunsell, P.; Jin Li.

1989-11-01

The inductive coupling between the plasma and the four octupole field coils in the Extrap T1 device is utilized as a means of estimating the plasma position. The current in each octupole ring as well as the plasma current is measured by a Rogowski coil and the ring - plasma mutual inductance is then computed assuming axisymmetric plasma displacements. The obtained position is in agreement with internal magnetic probe measurements. The time - evolution of the plasma position for different external vertical and toroidal field strengths is studied. For the present discharge parameter a vertical field of about .008 T is found to give an almost radially stationary plasma. The results are compared with a simple equilibrium model

Beam pinging, sweeping, shaking, and electron/ion collecting, at the Proton Storage Ring

International Nuclear Information System (INIS)

Hardek, T.W.; Macek, R.J.; Plum, M.A.; Wang, T.S.F.

1993-01-01

We have built, installed and tested a pinger for use as a general diagnostic at the Los Alamos Proton Storage Ring (PSR). Two 4-m-long parallel-plate electrodes with a plate spacing of 10.2 cm provide kicks of up to 1.1 mrad. A pair of solid-state pulsers may be operated in a single-pulse mode for beam pinging (tune measurements) or in a burst mode at up to 700 kHz pulse rates for beam sweeping. During our 1992 operating period we used the pinger for beam sweeping, for beam shaking, for measuring the tune shift, and we have used it as an ion chamber. Using the pinger as an ion chamber during production conditions has yielded some surprising results

Persistent current and transmission probability in the Aharonov-Bohm ring with an embedded quantum dot

International Nuclear Information System (INIS)

Wu Suzhi; Li Ning; Jin Guojun; Ma Yuqiang

2008-01-01

Persistent current and transmission probability in the Aharonov-Bohm (AB) ring with an embedded quantum dot (QD) are studied using the technique of the scattering matrix. For the first time, we find that the persistent current can arise in the absence of magnetic flux in the ring with an embedded QD. The persistent current and the transmission probability are sensitive to the lead-ring coupling and the short-range potential barrier. It is shown that increasing the lead-ring coupling or the short-range potential barrier causes the suppression of the persistent current and the increasing resonance width of the transmission probability. The effect of the potential barrier on the number of the transmission peaks is also investigated. The dependence of the persistent current and the transmission probability on the magnetic flux exhibits a periodic property with period of the flux quantum

COMMISSIONING CNI PROTON POLARIMETERS IN RHIC

International Nuclear Information System (INIS)

HUANG, H.; BRAVAR, A.; LI, Z.; MACKAY, W.W.; MAKDISI, Y.; RESCIA, S.; ROSER, T.; SURROW, B.; BUNCE, G.; DESHPANDE, A.; GOTO, Y.; ET AL

2002-01-01

Two polarimeters based on proton carbon elastic scattering in the Coulomb Nuclear Interference (CNI) region have been installed and commissioned in the Blue and Yellow rings of RHIC during the first RHIC polarized proton collider run. Each polarimeter consists of ultra-thin carbon targets and six silicon detectors. With newly developed wave form digitizers, they provide fast and reliable polarization information for both rings

An outline of research facilities of high intensity proton accelerator

International Nuclear Information System (INIS)

Tanaka, Shun-ichi

1995-01-01

A plan called PROTON ENGINEERING CENTER has been proposed in JAERI. The center is a complex composed of research facilities and a beam shape and storage ring based on a proton linac with an energy of 1.5 GeV and an average current of 10 mA. The research facilities planned are OMEGA·Nuclear Energy Development Facility, Neutron Facility for Material Irradiation, Nuclear Data Experiment Facility, Neutron Factory, Meson Factory, spallation Radioisotope Beam Facility, and Medium Energy Experiment Facility, where high intensity proton beam and secondary particle beams such as neutrons, π-mesons, muons, and unstable isotopes originated from the protons are available for promoting the innovative research of nuclear energy and basic science and technology. (author)

Progress in the production of intense ion beams and the formation of proton layers

International Nuclear Information System (INIS)

Kapetanakos, C.A.; Golden, J.; Marsh, S.J.; Mahaffey, R.A.

1977-01-01

The results on ion sources and the application of ion beams to the formation of proton layers and rings are presented. Ion beams have been produced on three different generators. Some results from the experiments performed on the Gamble 2 generator are presented. The Gamble 2 generator with coaxial anode-cathode configuration, hollow beam cross-section produces power levels of 0.6-1.2 MV with peak ion current of 200 kA. The number of protons in the beam 4x10 16 . Peak ion currents is excess 200 kA, energy 1 MeV, ion current density 1 kA/cm 2 . Magnetic field configuration to provide formation of strong proton layers is shown

On the propagation and decay of North Brazil Current rings

Science.gov (United States)

Jochumsen, Kerstin; Rhein, Monika; Hüttl-Kabus, Sabine; BöNing, Claus W.

2010-10-01

Near the western boundary of the tropical North Atlantic, where the North Brazil Current (NBC) retroflects into the North Equatorial Countercurrent, large anticyclonic rings are shed. After separating from the retroflection region, the so-called NBC rings travel northwestward along the Brazilian coast, until they reach the island chain of the Lesser Antilles and disintegrate. These rings contribute substantially to the upper limb return flow of the Atlantic Meridional Overturning Circulation by carrying South Atlantic Water into the northern subtropical gyre. Their relevance for the northward transport of South Atlantic Water depends on the frequency of their generation as well as on their horizontal and vertical structure. The ring shedding and propagation and the complex interaction of the rings with the Lesser Antilles are investigated in the ? Family of Linked Atlantic Model Experiments (FLAME) model. The ring properties simulated in FLAME reach the upper limit of the observed rings in diameter and agree with recent observations on seasonal variability, which indicates a maximum shedding during the first half of the year. When the rings reach the shallow topography of the Lesser Antilles, they are trapped by the island triangle of St. Lucia, Barbados and Tobago and interact with the island chain. The model provides a resolution that is capable of resolving the complex topographic conditions at the islands and illuminates various possible fates for the water contained in the rings. It also reproduces laboratory experiments that indicate that both cyclones and anticyclones are formed after a ring passes through a topographic gap. Trajectories of artificial floats, which were inserted into the modeled velocity field, are used to investigate the pathways of the ring cores and their fate after they encounter the Lesser Antilles. The majority of the floats entered the Caribbean, while the northward Atlantic pathway was found to be of minor importance. No prominent

First observation of neutral current proton electron scattering at √s = 300 GeV

International Nuclear Information System (INIS)

Hasegawa, Takuya

1993-02-01

Neutral current proton electron scattering at center of mass energy 295 GeV was observed for the first time, using the newly built proton electron collider HERA (Hadron Elektron Ring Anlage) and the general purpose detector ZEUS. The distributions of Q 2 , Bjorken-x(x) and Bjorken-y(y) were compared with the expectation based on the standard electroweak theory and QCD. Regarding the investigation of high-Q 2 region, an event of Q 2 ∼ 1000 GeV 2 was observed for the first time. From the x-distribution of the events, a limit on the mass and the coupling of an exotic s-channel resonance of a quark-lepton system (leptoquark) was obtained. The mass limit is 72 GeV(97 GeV) at 95% confidence level for a scalar type leptoquark with a left-handed (right-handed) electromagnetic coupling to ordinary leptons. The leptoquark is assumed to be weak-isoscalar. To realize this experiment a uranium scintillator sandwich type calorimeter was developed. Equal response to electrons and hadrons (e/h = 1), which is essential for the good energy resolution for hadrons, has been achieved. One of the main characteristics of this calorimeter is a possibility of calibration utilizing of its own uranium radioactivity. The grain variation of each channel can be detected with an accuracy of ± 1 %. (J.P.N.) 65 refs

Survey of Digital Feedback Systems in High Current Storage Rings

International Nuclear Information System (INIS)

Teytelman, Dmitry

2003-01-01

In the last decade demand for brightness in synchrotron light sources and luminosity in circular colliders led to construction of multiple high current storage rings. Many of these new machines require feedback systems to achieve design stored beam currents. In the same time frame the rapid advances in the technology of digital signal processing allowed the implementation of these complex feedback systems. In this paper I concentrate on three applications of feedback to storage rings: orbit control in light sources, coupled-bunch instability control, and low-level RF control. Each of these applications is challenging in areas of processing bandwidth, algorithm complexity, and control of time-varying beam and system dynamics. I will review existing implementations as well as comment on promising future directions

Proton NMR for Measuring Quantum Level Crossing in the Magnetic Molecular Ring Fe10

International Nuclear Information System (INIS)

Julien, M.; Jang, Z.H.; Borsa, F.; Julien, M.; Lascialfari, A.; Borsa, F.; Horvatic, M.; Caneschi, A.; Gatteschi, D.

1999-01-01

The proton nuclear spin-lattice relaxation rate 1/T 1 has been measured as a function of temperature and magnetic field (up to 15thinspthinspT) in the molecular magnetic ring Fe 10 ( OCH 3 ) 20 (O 2 CCH 2 Cl) 10 (Fe10). Striking enhancement of 1/T 1 is observed around magnetic field values corresponding to a crossing between the ground state and the excited states of the molecule. We propose that this is due to a cross-relaxation effect between the nuclear Zeeman reservoir and the reservoir of the Zeeman levels of the molecule. This effect provides a powerful tool to investigate quantum dynamical phenomena at level crossing. copyright 1999 The American Physical Society

Constraining the proton structure at ATLAS

CERN Document Server

Tricoli, Alessandro; Viehhauser, Georg

Particle physics is at a pivotal moment: the origin of mass and new physics scenarios beyond the Standard Model or particle physics could be unveiled in the coming year. In 2007 the most powerful particl e accelerator, the Large Hadron Coolider (LHC), will start colliding proton beams reaching the ihghest energy and luminosity ever in collider particle physics. The ATLAS detector is one of two general pu rpose detectors placed along the collider ring to fully exploit the LHC potential. The theoretical uncertainties on most of the LHC physics progream are dominated by the proton structure uncertaintiy. This thesis demonstrates that $W^{\\pm}$ boson productionis an ideal process to constr ain the proton strcuture uncertainty. The rapidity distributions of electrons and positrons originating respectively from the $W^-$ and $W^+$ decays have been analysed. The results show that the current uncertainty on the gluon content of the proton can be reduced by a very significant amount if the total systematic uncertaint...

SNS accumulator ring design and space charge considerations

International Nuclear Information System (INIS)

Weng, W.T.

1998-01-01

The goal of the proposed Spallation Neutron Source (SNS) is to provide a short pulse proton beam of about 0.5micros with average beam power of 1MW. To achieve such purpose, a proton storage ring operated at 60Hz with 1 x 10 14 protons per pulse at 1GeV is required. The Accumulator Ring (AR) receives 1msec long H - beam bunches of 28mA from a 1GeV linac. Scope and design performance goals of the AR are presented. About 1,200 turns of charge exchange injection is needed to accumulate 1mA in the ring. After a brief description of the lattice design and machine performance parameters, space charge related issues, such as: tune shifts, stopband corrections, halo generation and beam collimation etc. is discussed

Passive filter of the IFVE accelerator ring electromagnet

International Nuclear Information System (INIS)

Kaz'min, B.V.; Mojzhes, L.L.; Polyakov, Eh.V.; Radin, O.N.; Fedorov, Yu.A.

1977-01-01

Two circuits of two-link passive filters for suppressing the current pulsation in the ring electromagnet of a synchrotron are presented, as well as calculated and experimental (for one of the circuits) characteristics of these filters. It is shown that the coefficient of suppression of 600 hertz pulsations in the flat portion of a magnetic field pulse is 570 at an intensity corresponding to a slow proton ejection

The Cornell field-reversed ion ring experiment FIREX: experimental design and first results

International Nuclear Information System (INIS)

Podulka, W.J.; Greenly, J.B.; Anderson, D.E.; Glidden, S.C.; Hammer, D.A.; Omelchenko, Yu.A.; Sudan, R.N.

1996-01-01

The goal of FIREX (Field-reversed Ion Ring EXperiment) is to produce a fully field-reversed ring with 1 MeV protons. Such a ring requires about (2-3) x 10 17 protons, or 30-50 mC of charge. This charge is to be injected as an annular proton beam through a suitable magnetic cusp configuration to produce a compact ring. The critical design issues for the ion beam accelerator are described. First experimental results of ion diode operation indicate that the design is capable of producing the required beam parameters. (author). 4 figs., 4 refs

The Cornell field-reversed ion ring experiment FIREX: experimental design and first results

Energy Technology Data Exchange (ETDEWEB)

Podulka, W J; Greenly, J B; Anderson, D E; Glidden, S C; Hammer, D A; Omelchenko, Yu A; Sudan, R N [Cornell Univ., Ithaca, NY (United States). Laboratory of Plasma Studies

1997-12-31

The goal of FIREX (Field-reversed Ion Ring EXperiment) is to produce a fully field-reversed ring with 1 MeV protons. Such a ring requires about (2-3) x 10{sup 17} protons, or 30-50 mC of charge. This charge is to be injected as an annular proton beam through a suitable magnetic cusp configuration to produce a compact ring. The critical design issues for the ion beam accelerator are described. First experimental results of ion diode operation indicate that the design is capable of producing the required beam parameters. (author). 4 figs., 4 refs.

Energy content of stormtime ring current from phase space mapping simulations

International Nuclear Information System (INIS)

Chen, M.W.; Schulz, M.; Lyons, L.R.

1993-01-01

The authors perform a model study to account for the increase in energy content of the trapped-particle population which occurs during the main phase of major geomagnetic storms. They consider stormtime particle transport in the equatorial region of the magnetosphere. They start with a phase space distribution of the ring current before the storm, created by a steady state transport model. They then use a previously developed guiding center particle simulation to map the stormtime ring current phase space, following Liouville's theorem. This model is able to account for the ten to twenty fold increase in energy content of magnetospheric ions during the storm

Amide proton temperature coefficients as hydrogen bond indicators in proteins

International Nuclear Information System (INIS)

Cierpicki, Tomasz; Otlewski, Jacek

2001-01-01

Correlations between amide proton temperature coefficients (Δσ HN /ΔT) and hydrogen bonds were investigated for a data set of 793 amides derived from 14 proteins. For amide protons showing temperature gradients more positive than -4.6 ppb/K there is a hydrogen bond predictivity value exceeding 85%. It increases to over 93% for amides within the range between -4 and -1 ppb/K. Detailed analysis shows an inverse proportionality between amide proton temperature coefficients and hydrogen bond lengths. Furthermore, for hydrogen bonds of similar bond lengths, values of temperature gradients in α-helices are on average 1 ppb/K more negative than in β-sheets. In consequence, a number of amide protons in α-helices involved in hydrogen bonds shorter than 2 A show Δσ HN /ΔT 10 helices and 98% in β-turns have temperature coefficients more positive than -4.6ppb/K. Ring current effect also significantly influences temperature coefficients of amide protons. In seven out of eight cases non-hydrogen bonded amides strongly deshielded by neighboring aromatic rings show temperature coefficients more positive than -2 ppb/K. In general, amide proton temperature gradients do not change with pH unless they correspond to conformational changes. Three examples of pH dependent equilibrium showing hydrogen bond formation at higher pH were found. In conclusion, amide proton temperature coefficients offer an attractive and simple way to confirm existence of hydrogen bonds in NMR determined structures

Ionospheric storm effects in the nighttime E region caused by neutralized ring current particles

Directory of Open Access Journals (Sweden)

R. Bauske

1997-03-01

Full Text Available During magnetic storms an anomalous increase in the ionization density of the nighttime E region is observed at low and middle latitudes. It has been suggested that this effect is caused by the precipitation of neutralized ring current particles. Here a coupled ring current decay-ionosphere model is used to confirm the validity of this explanation.

Spin-dependent heat and thermoelectric currents in a Rashba ring coupled to a photon cavity

Science.gov (United States)

Abdullah, Nzar Rauf; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

2018-01-01

Spin-dependent heat and thermoelectric currents in a quantum ring with Rashba spin-orbit interaction placed in a photon cavity are theoretically calculated. The quantum ring is coupled to two external leads with different temperatures. In a resonant regime, with the ring structure in resonance with the photon field, the heat and the thermoelectric currents can be controlled by the Rashba spin-orbit interaction. The heat current is suppressed in the presence of the photon field due to contribution of the two-electron and photon replica states to the transport while the thermoelectric current is not sensitive to changes in parameters of the photon field. Our study opens a possibility to use the proposed interferometric device as a tunable heat current generator in the cavity photon field.

Giving Protons a Boost

CERN Multimedia

2004-01-01

The first of LHC's superconducting radio-frequency cavity modules has passed its final test at full power in the test area of building SM18. These modules carry an oscillating electric field that will accelerate protons around the LHC ring and help maintain the stability of the proton beams.

SNS accumulator ring design and space charge considerations

Energy Technology Data Exchange (ETDEWEB)

Weng, W.T.

1998-08-01

The goal of the proposed Spallation Neutron Source (SNS) is to provide a short pulse proton beam of about 0.5 {micro}s with average beam power of 1 MW. To achieve such purpose, a proton storage ring operated at 60 Hz with 1 {times} 10{sup 14} protons per pulse at 1 GeV is required. The Accumulator Ring (AR) receives 1 msec long H{sup {minus}} beam bunches of 28 mA from a 1 GeV linac. Scope and design performance goals of the AR are presented. About 1,200 turns of charge exchange injection is needed to accumulate 1 mA in the ring. After a brief description of the lattice design and machine performance parameters, space charge related issues, such as: tune shifts, stopband corrections, halo generatino and beam collimation etc. is discussed.

SNS ACCUMULATOR RING DESIGN AND SPACE CHARGE CONSIDERATIONS

Energy Technology Data Exchange (ETDEWEB)

WENG,W.T.

1998-05-04

The goal of the proposed Spallation Neutron Source (SNS) is to provide a short pulse proton beam of about 0.5{micro}s with average beam power of 1MW. To achieve such purpose, a proton storage ring operated at 60Hz with 1 x 10{sup 14} protons per pulse at 1GeV is required. The Accumulator Ring (AR) receives 1msec long H{sup {minus}} beam bunches of 28mA from a 1GeV linac. Scope and design performance goals of the AR are presented. About 1,200 turns of charge exchange injection is needed to accumulate 1mA in the ring. After a brief description of the lattice design and machine performance parameters, space charge related issues, such as: tune shifts, stopband corrections, halo generation and beam collimation etc. is discussed.

Non-Markovian response of ultrafast coherent electronic ring currents in chiral aromatic molecules in a condensed phase

International Nuclear Information System (INIS)

Mineo, H.; Lin, S. H.; Fujimura, Y.; Xu, J.; Xu, R. X.; Yan, Y. J.

2013-01-01

Results of a theoretical study on non-Markov response for femtosecond laser-driven coherent ring currents in chiral aromatic molecules embedded in a condensed phase are presented. Coherent ring currents are generated by coherent excitation of a pair of quasi-degenerated π-electronic excited states. The coherent electronic dynamical behaviors are strongly influenced by interactions between the electronic system and phonon bath in a condensed phase. Here, the bath correlation time is not instantaneous but should be taken to be a finite time in ultrashort time-resolved experiments. In such a case, Markov approximation breaks down. A hierarchical master equation approach for an improved semiclassical Drude dissipation model was adopted to examine the non-Markov effects on ultrafast coherent electronic ring currents of (P)-2,2 ′ -biphenol in a condensed phase. Time evolution of the coherent ring current derived in the hierarchical master equation approach was calculated and compared with those in the Drude model in the Markov approximation and in the static limit. The results show how non-Markovian behaviors in quantum beat signals of ring currents depend on the Drude bath damping constant. Effects of temperatures on ultrafast coherent electronic ring currents are also clarified

Status of the MEIC ion collider ring design

International Nuclear Information System (INIS)

Morozov, Vasiliy; Derbenev, Yaroslav; Harwood, Leigh; Hutton, Andrew; Lin, Fanglei; Pilat, Fulvia; Zhang, Yuhong; Cai, Yunhai; Nosochkov, Y. M.; Sullivan, Michael; Wang, M.-H.; Wienands, Uli; Gerity, James; Mann, Thomas; McIntyre, Peter; Pogue, Nathaniel; Sattarov, Akhdiyor

2015-09-01

We present an update on the design of the ion collider ring of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The design is based on the use of super-ferric magnets. It provides the necessary momentum range of 8 to 100 GeV/c for protons and ions, matches the electron collider ring design using PEP-II components, fits readily on the JLab site, offers a straightforward path for a future full-energy upgrade by replacing the magnets with higher-field ones in the same tunnel, and is more cost effective than using presently available current-dominated super-conducting magnets. We describe complete ion collider optics including an independently-designed modular detector region.

Status of the MEIC ion collider ring design

International Nuclear Information System (INIS)

Morozov, V. S.; Derbenev, Ya. S.; Harwood, L.; Hutton, A.; Lin, F.; Pilat, F.; Zhang, Y.; Cai, Y.; Nosochkov, Y. M.; Sullivan, M.; Wang, M-H; Wienands, U.; Gerity, J.; Mann, T.; McIntyre, P.; Pogue, N. J.; Satttarov, A.

2015-01-01

We present an update on the design of the ion collider ring of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The design is based on the use of super-ferric magnets. It provides the necessary momentum range of 8 to 100 GeV/c for protons and ions, matches the electron collider ring design using PEP-II components, fits readily on the JLab site, offers a straightforward path for a future full-energy upgrade by replacing the magnets with higher-field ones in the same tunnel, and is more cost effective than using presently available current-dominated superconducting magnets. We describe complete ion collider optics including an independently-designed modular detector region.

Heavy ion storage rings

International Nuclear Information System (INIS)

Schuch, R.

1987-01-01

A brief overview of synchrotron storage rings for heavy ions, which are presently under construction in different accelerator laboratories is given. Ions ranging from protons up to uranium ions at MeV/nucleon energies will be injected into these rings using multiturn injection from the accelerators available or being built in these laboratories. After injection, it is planned to cool the phase space distribution of the ions by merging them with cold electron beams or laser beams, or by using stochastic cooling. Some atomic physics experiments planned for these rings are presented. 35 refs

Electronic States and Persistent Currents in Nanowire Quantum Ring

Science.gov (United States)

Kokurin, I. A.

2018-04-01

The new model of a quantum ring (QR) defined inside a nanowire (NW) is proposed. The one-particle Hamiltonian for electron in [111]-oriented NW QR is constructed taking into account both Rashba and Dresselhaus spin-orbit coupling (SOC). The energy levels as a function of magnetic field are found using the exact numerical diagonalization. The persistent currents (both charge and spin) are calculated. The specificity of SOC and arising anticrossings in energy spectrum lead to unusual features in persistent current behavior. The variation of magnetic field or carrier concentration by means of gate can lead to pure spin persistent current with the charge current being zero.

Los Alamos Proton Storage Ring (PSR) injection deflector system

International Nuclear Information System (INIS)

Jason, A.j.; Higgins, E.F.; Koelle, A.R.

1983-01-01

We describe a pulsed magnetic deflector system planned for the injection system of the PSR. Two sets of magnets, appropriately placed in the optical systems of both the ring and the injection transport line, provide control of the rate at which particles are injected into a given portion of transverse phase space and limit the interaction of stored beam with the injection stripping foil. High-current modulators that produce relatively complex waveforms are required for this purpose. Solid-state drivers using direct feedback to produce the necessary waveforms are discussed as replacements for the more conventional high-voltage tube technology

Current's Fluctuations through Molecular Wires Composed of Thiophene Rings.

Science.gov (United States)

Ojeda Silva, Judith Helena; Cortés Peñaranda, Juan Camilo; Gómez Castaño, Jovanny A; Duque, Carlos Alberto

2018-04-11

We study theoretically the electronic transport and quantum fluctuations in single-molecule systems using thiophene rings as integrated elementary functions, as well as the dependence of these properties with the increase of the coupled rings, i.e., as a quantum wire. In order to analyze the current flow through these molecular systems, the thiophene rings are considered to be connected to metal contacts, which, in general terms, will be related to the application of voltages (bias voltages or gate voltages) to generate non-equilibrium behavior between the contacts. Due to the nonlinear behavior that is generated when said voltages are applied, it is possible to observe quantum fluctuations in the transport properties of these molecular wires. For the calculation of the transport properties, we applied a tight-binding approach using the Landauer-Büttiker formalism and the Fischer-Lee relationship, by means of a semi-analytic Green's function method within a real-space renormalization (decimation procedure). Our results showed an excellent agreement with results using a tight-binding model with a minimal number of parameters reported so far for these molecular systems.

A cryogenic current-measuring device with nano-ampere resolution at the storage ring TARN II

International Nuclear Information System (INIS)

Tanabe, T.; Chida, K.; Shinada, K.

1999-01-01

In cooler-ring experiments, an accurate and non-destructive current measurement is essential for determining the reaction cross sections. The lowest current which can be measured by the DC current transformer commonly used so far is some μA. In order to measure a low-beam current from nA to μA, we made a cryogenic current-measuring device using a superconducting quantum interference devices (SQUID), and measured the circulating ion current at the cooler ring TARN II. This paper gives the design and performance of the device

Storage rings, internal targets and PEP

International Nuclear Information System (INIS)

Spencer, J.E.

1986-11-01

Storage rings with internal targets are described, using PEP as an example. The difference between electrons and heavier particles such as protons, antiprotons, and heavy ions is also discussed because it raises possibilities of bypass insertions for more exotic experiments. PEP is compared to other rings in various contexts to verify the assertion that it is an ideal ring for many fundamental and practical applications that can be carried on simultaneously

Inductive fault current limiter based on multiple superconducting rings of small diameter

International Nuclear Information System (INIS)

Osorio, M R; Cabo, L; Veira, J A; Vidal, F

2004-01-01

We present a fault current limiter prototype based on the use of a secondary comprised of an array of magnetic cores of small sections, each one of them with several superconducting rings. The main advantage of this configuration is that it is easier to make small diameter superconducting rings which, in addition, are more homogeneous and allow better refrigeration. We then present detailed measurements that show that, in addition to these advantages, this prototype offers the same limitation performances than when using a unique core and a superconducting ring with an equivalent area as the array of small section cores

Design of a High Luminosity 100 TeV Proton Antiproton Collider

Energy Technology Data Exchange (ETDEWEB)

Oliveros Tuativa, Sandra Jimena [Univ. of Mississippi, Oxford, MS (United States)

2017-04-01

Currently new physics is being explored with the Large Hadron Collider at CERN and with Intensity Frontier programs at Fermilab and KEK. The energy scale for new physics is known to be in the multi-TeV range, signaling the need for a future collider which well surpasses this energy scale. A 10$^{\\,34}$ cm$^{-2}$ s$^{-1}$ luminosity 100 TeV proton-antiproton collider is explored with 7$\\times$ the energy of the LHC. The dipoles are 4.5\\,T to reduce cost. A proton-antiproton collider is selected as a future machine for several reasons. The cross section for many high mass states is 10 times higher in $p\\bar{p}$ than $pp$ collisions. Antiquarks for production can come directly from an antiproton rather than indirectly from gluon splitting. The higher cross sections reduce the synchrotron radiation in superconducting magnets and the number of events per bunch crossing, because lower beam currents can produce the same rare event rates. Events are also more centrally produced, allowing a more compact detector with less space between quadrupole triplets and a smaller $\\beta^{*}$ for higher luminosity. To adjust to antiproton beam losses (burn rate), a Fermilab-like antiproton source would be adapted to disperse the beam into 12 different momentum channels, using electrostatic septa, to increase antiproton momentum capture 12 times. At Fermilab, antiprotons were stochastically cooled in one Debuncher and one Accumulator ring. Because the stochastic cooling time scales as the number of particles, two options of 12 independent cooling systems are presented. One electron cooling ring might follow the stochastic cooling rings for antiproton stacking. Finally antiprotons in the collider ring would be recycled during runs without leaving the collider ring, by joining them to new bunches with snap bunch coalescence and synchrotron damping. These basic ideas are explored in this work on a future 100 TeV proton-antiproton collider and the main parameters are presented.

Design of a High Luminosity 100 TeV Proton-Antiproton Collider

Science.gov (United States)

Oliveros Tautiva, Sandra Jimena

Currently new physics is being explored with the Large Hadron Collider at CERN and with Intensity Frontier programs at Fermilab and KEK. The energy scale for new physics is known to be in the multi-TeV range, signaling the need for a future collider which well surpasses this energy scale. A 10 34 cm-2 s-1 luminosity 100 TeV proton-antiproton collider is explored with 7x the energy of the LHC. The dipoles are 4.5 T to reduce cost. A proton-antiproton collider is selected as a future machine for several reasons. The cross section for many high mass states is 10 times higher in pp than pp collisions. Antiquarks for production can come directly from an antiproton rather than indirectly from gluon splitting. The higher cross sections reduce the synchrotron radiation in superconducting magnets and the number of events per bunch crossing, because lower beam currents can produce the same rare event rates. Events are also more centrally produced, allowing a more compact detector with less space between quadrupole triplets and a smaller beta* for higher luminosity. To adjust to antiproton beam losses (burn rate), a Fermilab-like antiproton source would be adapted to disperse the beam into 12 different momentum channels, using electrostatic septa, to increase antiproton momentum capture 12 times. At Fermilab, antiprotons were stochastically cooled in one Debuncher and one Accumulator ring. Because the stochastic cooling time scales as the number of particles, two options of 12 independent cooling systems are presented. One electron cooling ring might follow the stochastic cooling rings for antiproton stacking. Finally antiprotons in the collider ring would be recycled during runs without leaving the collider ring, by joining them to new bunches with snap bunch coalescence and synchrotron damping. These basic ideas are explored in this work on a future 100 TeV proton-antiproton collider and the main parameters are presented.

Photoinduced electric currents in ring-shaped molecules by circularly polarized laser pulses

International Nuclear Information System (INIS)

Nobusada, Katsuyuki; Yabana, Kazuhiro

2007-01-01

We have theoretically demonstrated that circularly polarized laser pulses induce electric currents and magnetic moments in ring-shaped molecules Na 10 and benzene. The time-dependent adiabatic local density approximation is employed for this purpose, solving the time-dependent Kohn-Sham equation in real space and real time. It has been found that the electric currents are induced efficiently and persist continuously even after the laser pulses were switched off provided the frequency of the applied laser pulse is in tune with the excitation energy of the electronic excited state with the dipole strength for each molecular system. The electric currents are definitely revealed to be a second-order nonlinear optical response to the magnitude of the electric field. The magnetic dipole moments inevitably accompany the ring currents, so that the molecules are magnetized. The production of the electric currents and the magnetic moments in the present procedure is found to be much more efficient than that utilizing static magnetic fields

Beam Aborts in PEP-II Rings and Lingering Drift Chamber Currents

International Nuclear Information System (INIS)

Meshkat, N.

2004-01-01

The BABAR detector at SLAC was designed to study CP-violation in B-meson decays from electron-positron collisions in the PEP-II electron-positron storage rings. Background radiation in the High Energy Ring (HER) and Low Energy Ring (LER) of PEP-II has the potential to damage the sensitive equipment in the BABAR detector. As a result, the beams in the HER and LER can be aborted to prevent such damage. In the span of a few microseconds, the HER and LER currents drop from, for example, 1450 micro Amps and 2300 micro Amps, respectively, to zero. At this time the voltage in the Drift Chamber is rapidly ramped down from a potential of 1930 V to a safe potential of 800 V, thus we would expect the currents in the Drift Chamber to quickly go to zero once the beams are aborted. However, we observe an average 15 second delay in the measured time it takes for all current in the Drift Chamber to fall below 1 micro Amp. This delay has been hypothesized as an instrumentation issue and not as a physical phenomenon. The specific sources of this error are still not completely known, but analysis suggests that it results from the interplay of the CAEN High Voltage supplies and the EPICS system and/or limitations within those systems

The storm-time ring current: a statistical analysis at two widely separated low-latitude stations

Directory of Open Access Journals (Sweden)

P. Francia

2004-11-01

Full Text Available We conducted a statistical analysis of the geomagnetic field variations during the storm main phase at two low-latitude stations, separated by several hours in magnetic local time, in order to investigate the asymmetry and longitudinal extent of the storm-time ring current. The results show evidence for an asymmetric current which typically extends from evening to noon and, during moderate solar wind electric field conditions, up to the early morning, confirming the important role of the magnetospheric convection in the ring current energization. We also analyzed a possible relationship between the local current intensity during the storm main phase and the substorm activity observed at different time delays τ with respect to the storm onset. The results show a significant anticorrelation for τ =-1h, indicating that if the substorm activity is high just before the storm, a weaker ring current develops.

Proposal for construction of a proton--proton storage accelerator facility (Isabelle)

International Nuclear Information System (INIS)

1975-06-01

A proposal is made for the construction of proton storage rings at the Brookhaven Alternating Gradient Synchrotron (AGS) using superconducting magnets for which much of the technology has already been developed. This proton-proton colliding beam facility, ''ISABELLE,'' will provide large increases in both the center-of-mass energy and the luminosity, key machine parameters for high energy physics. The physics potential and the general description of the facility are discussed in detail, and the physical plant layout, a cost estimate and schedule, and future options are given.(U.S.)

The O+ contribution and role on the ring current pressure development for CMEs and CIRs using Van Allen Probes observations

Science.gov (United States)

Mouikis, C.; Bingham, S.; Kistler, L. M.; Farrugia, C. J.; Spence, H. E.; Gkioulidou, M.

2016-12-01

The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), co-rotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure change the global magnetic field, which affects the transport of the radiation belts. In order to determine the field changes during a storm, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. The source population of the storm time ring current is the night side plasma sheet. We use Van Allen Probes observations to determine the ring current pressure contribution of the convecting plasma sheet H+ and O+ particles in the storm time development of the ring current. We compare storms that are related to different interplanetary drivers, CMEs and CIRs, as observed at different local times. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L 2 and their pressure compares to the local magnetic field pressure as deep as L 3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current. However, the largest difference between the CME and CIR ring current responses during the storm main and early recovery phases is caused by how the 15 - 60 keV O+ responds to these drivers.

Second law analysis of the helium refrigerators for the HERA proton magnet ring

International Nuclear Information System (INIS)

Ziegler, B.O.

1986-01-01

Each of the three refrigerators for the HERA proton magnet ring must provide 6.775 kW of refrigeration at 4.3 0 K plus 20.5 g/s of helium at 2.5 bar and 4.5 0 K for leads cooling and 20 kW of refrigeration at 40-80 0 K for shield cooling. The capital cost of large refrigerators is small compared with operating costs. Therefore the refrigeration process was analysed on the basis of exergy. This means the irreversibility of each component is expressed as power input into the plant. The process realised consists of the turbine cycle, divided into two streams with 5 gas bearing turbines all together, and the Joule Thomson cycle. Special attention was paid to the cold end of the plant. The optimization resulted in a new configuration with two turboexpanders running in parallel on different temperature levels

Modeling photo-desorption in high current storage rings

International Nuclear Information System (INIS)

Barletta, W.A.

1991-01-01

High luminosity flavor factories are characterized by high fluxes of synchrotron radiation that lead to thermal management difficulties. The associated photo-desorption from the vacuum chamber walls presents an additional design challenge, providing a vacuum system suitable for maintaining acceptable beam-gas lifetimes and low background levels of scattered radiation in the detector. Achieving acceptable operating pressures (1-10 nTorr) with practical pumping schemes requires the use of materials with low photodesorption efficiency operating in a radiation environment beyond that of existing storage rings. Extrapolating the existing photo-desorption data base to the design requirements of high luminosity colliders requires a physical model of the differential cleaning in the vacuum chamber. The authors present a simple phenomenological model of photodesorption that includes effects of dose dependence and diffuse photon reflection to compute the leveling of gas loads in beamlines of high current storage rings that typify heavy flavor factories. This model is also used to estimate chamber commissioning times

MEIC Proton Beam Formation with a Low Energy Linac

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yuhong [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

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.

Microwave proton source development for a high-current linac injector

International Nuclear Information System (INIS)

Sherman, J.; Bolme, G.; Geisik, C.

1995-01-01

Powerful CW proton linear accelerators (100-mA at 0.5--1.0 GeV) are being proposed for spallation neutron-source applications. A 75-keV, 110-mA dc proton injector using a microwave ion source is being tested for these applications. It has achieved 80-keV, 110-mA hydrogen-ion-beam operation. Video and dc beam-current toroid diagnostics are operational, and an EPICS control system is also operational on the 75-keV injector. A technical base development program has also been carried out on a 50-keV injector obtained from Chalk River Laboratories, and it includes low-energy beam transport studies, ion source lifetime tests, and proton-fraction enhancement studies. Technical base results and the present status of the 75-keV injector will be presented

An analysis of the long-term stability of the particle dynamics in hadron storage rings

International Nuclear Information System (INIS)

Bruening, O.S.

1994-05-01

This thesis extends the stability analysis of the particle motion in a storage ring and estimates the diffusion rates well inside the dynamic aperture. The calculation of the drift and diffusion coefficients focuses on an application to the proton storage ring in HERA, where the proton beam lifetime drops considerably after the proton and electron beams are brought to collision. The analysis shows that the combined effect of slow and fast modulation frequencies leads to an increased emittance growth in the storage ring. HERA the slow frequency components are caused by ground motion in the HERA tunnel and the fast frequency components by ripples in the power supplies. The thesis provides upper limits for the modultion depths of a fast tune modulation which result in tolerable growth rates for the proton emittance. The analytically calculated drift coefficients agree numerical simulations for the particle dynamics. A comparison of the calculated drift coefficients with those measured in the HERA proton storage ring shows that the analyzed mechanism can lead to growth rates of the same order of magnitude as the ones measured during the luminosity operation in the HERA storage ring. Analytical estimates for the proton growth rates predict a high sensitivity to the particle diffusion on the frequency components of the fast fast tune modulation. This prediction was confirmed by a subsequent modulation experiment in the proton storage ring of HERA, where an external tune modulation with fast frequency components led to a drastic increase in the growth rates

Proton magnetic resonance study of the influence of chemical modification, mutation, quaternary state, and ligation state on dynamic stability of the heme pocket in hemoglobin as reflected in the exchange of the proximal histidyl ring labile proton

International Nuclear Information System (INIS)

Han, K.H.; La Mar, G.N.; Nagai, K.

1989-01-01

Proton nuclear magnetic resonance spectroscopy has been utilized to investigate the rates of exchange with deuterium of the proximal histidyl ring protons in a series of chemically modified and mutated forms of Hb A. Differences in rates of exchange are related to differences in the stability of the deformed or partially unfolded intermediates from which exchange with bulk solvent takes place. Each modified/mutated Hb exhibited kinetic subunit heterogeneity in the reduced ferrous state, with the alpha subunit exhibiting faster exchange than the beta subunit. Modification or mutation resulted in significant increases in the His F8 ring NH exchange rates primarily for the affected subunit and only if the modification/mutation occurs at the allosterically important alpha 1 beta 2 subunit interface. Moreover, this enhancement in exchange rate is observed primarily in that quaternary state of the modified/mutated Hb in which the modified/substituted residue makes the intersubunit contact. This confirms the importance of allosteric constraints in determining the dynamic properties of the heme pocket. Using modified or mutated Hbs that can switch between the alternate quaternary states within a given ligation state or ligate within a given quaternary state, we show that the major portion of the enhanced exchange rate in R-state oxy Hb relative to T-state deoxy Hb originates from the quaternary switch rather than from ligation. However, solely ligation effects are not negligible. The exchange rates of the His F8 ring labile protons increase dramatically upon oxidizing the iron to the ferric state, and both the subunit kinetic heterogeneity and the allosteric sensitivity to the quaternary state are essentially abolished

Persistent current of relativistic electrons on a Dirac ring in presence of impurities

KAUST Repository

Ghosh, Sumit; Saha, Arijit

2014-01-01

We study the behaviour of persistent current of relativistic electrons on a one dimensional ring in presence of attractive/repulsive scattering potentials. In particular, we investigate the persistent current in accordance with the strength as well as the number of the scattering potential. We find that in presence of single scatterer the persistent current becomes smaller in magnitude than the scattering free scenario. This behaviour is similar to the non-relativistic case. Even for a very strong scattering potential, finite amount of persistent current remains for a relativistic ring. In presence of multiple scatterer we observe that the persistent current is maximum when the scatterers are placed uniformly compared to the current averaged over random configurations. However if we increase the number of scatterers, we find that the random averaged current increases with the number of scatterers. The latter behaviour is in contrast to the non-relativistic case. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Persistent current of relativistic electrons on a Dirac ring in presence of impurities

KAUST Repository

Ghosh, Sumit

2014-08-01

We study the behaviour of persistent current of relativistic electrons on a one dimensional ring in presence of attractive/repulsive scattering potentials. In particular, we investigate the persistent current in accordance with the strength as well as the number of the scattering potential. We find that in presence of single scatterer the persistent current becomes smaller in magnitude than the scattering free scenario. This behaviour is similar to the non-relativistic case. Even for a very strong scattering potential, finite amount of persistent current remains for a relativistic ring. In presence of multiple scatterer we observe that the persistent current is maximum when the scatterers are placed uniformly compared to the current averaged over random configurations. However if we increase the number of scatterers, we find that the random averaged current increases with the number of scatterers. The latter behaviour is in contrast to the non-relativistic case. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Proton flux under radiation belts: near-equatorial zone

International Nuclear Information System (INIS)

Grigoryan, O.R.; Panasyuk, M.I.; Petrov, A.N.; Kudela, K.

2005-01-01

In this work the features of low-energy proton flux increases in near-equatorial region (McIlvein parameter L th the proton flux (with energy from tens keV up to several MeV) increases are registering regularly. However modern proton flux models (for example AP8 model) works at L>1.15 only and does not take into account near-equatorial protons. These fluxes are not too big, but the investigation of this phenomenon is important in scope of atmosphere-ionosphere connections and mechanisms of particles transport in magnetosphere. In according to double charge-exchange model the proton flux in near-equatorial region does not depend on geomagnetic local time (MLT) and longitude. However the Azur satellite data and Kosmos-484, MIR station and Active satellite data revealed the proton flux dependence on longitude. The other feature of near-equatorial proton flux is the dependence on geomagnetic local time revealed in the Sampex satellite experiment and other experiments listed above. In this work the dependences on MLT and longitude are investigated using the Active satellite (30-500 keV) and Sampex satellite (>800 keV). This data confirms that main sources of near-equatorial protons are radiation belts and ring current. The other result is that near-equatorial protons are quasi-trapped. The empirical proton flux dependences on L, B at near-equatorial longitudes are presented. (author)

The Effects of Hydrogen Band EMIC Waves on Ring Current H+ Ions

Science.gov (United States)

Wang, Zhiqiang; Zhai, Hao; Gao, Zhuxiu

2017-12-01

Hydrogen band electromagnetic ion cyclotron (EMIC) waves have received much attention recently because they are found to frequently span larger spatial areas than the other band EMIC waves. Using test particle simulations, we study the nonlinear effects of hydrogen band EMIC waves on ring current H+ ions. A dimensionless parameter R is used to characterize the competition between wave-induced and adiabatic motions. The results indicate that there are three regimes of wave-particle interactions for typical 35 keV H+ ions at L = 5: diffusive (quasi-linear) behavior when αeq ≤ 35° (R ≥ 2.45), the nonlinear phase trapping when 35° < αeq < 50° (0.75 < R < 2.45), and both the nonlinear phase bunching and phase trapping when αeq ≥ 50° (R ≤ 0.75). The phase trapping can transport H+ ions toward large pitch angle, while the phase bunching has the opposite effect. The phase-trapped H+ ions can be significantly accelerated (from 35 keV to over 500 keV) in about 4 min and thus contribute to the formation of high energy components of ring current ions. The results suggest that the effect of hydrogen band EMIC waves is not ignorable in the nonlinear acceleration and resonance scattering of ring current H+ ions.

Some remarks on the design of HIF current multiplication rings

International Nuclear Information System (INIS)

Reich, K.H.

1983-12-01

The conceptual design of heavy ion fusion drivers has now reached a state, where the overall approach has become fairly clear. One design features an RF linac plus current and beam multiplication rings. The present remarks concern the assignment of multiturn injection, beam storage and bunching to an optimized number of rings and transport lines, as well as some criteria for their designs. The main parameter constraints are discussed, showing how they can be met, although there is little flexibility at the present stage of understanding and technology. A shortened version of this report is scheduled for presentation at the ''INS International Symposium on Heavy Ion Accelerators and Their Application to Inertial Fusion'' Tokyo, January 23-27 1984. (author)

New developments on the e-p instability at the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Macek, R.J.; Browman, A.; Fitzgerald, D.H.; McCrady, R.; Plum, M.; Spickermann, T.

2001-01-01

New results are reported from an R and D program aimed greater understanding and control of the e-p instability observed at the Los Alamos Proton Storage Rings (PSR). Numerous characteristics of the electron cloud for both stable and unstable beams in PSR were measured with ANL electron analyzers and various collection plates. Strong suppression of the electron flux density by TiN coating of the vacuum chamber in a straight section was also observed, thereby confirming an essential role for secondary emission at the walls. Landau Damping by a variety of techniques including higher rf voltage, transverse coupling, multipole fields in the lattice, and the use of inductive inserts has been effective in controlling the e-p instability. By these methods, the instability threshold has been raised significantly to 9.7 micro Coulombs per stored pulse. (author)

Current status of the AUSTRON project

International Nuclear Information System (INIS)

Rauch, H.; Regler, M.; Lechner, R.E.; Weber, H.

2001-01-01

The current status of the AUSTRON spallation source project is described with reference to the need for neutrons in Europe and - due to a certain West-East imbalance of large research facilities - especially in Central Europe. A short overview about technical aspects of proton accelerator, rapid cycling synchrotron, storage ring, target and instrumentation is presented. (author)

Ring current and auroral electrojets in connection with interplanetary medium parameters during magnetic storm

Directory of Open Access Journals (Sweden)

Y. I. Feldstein

1994-06-01

Full Text Available The relationship between the auroral electrojet indices (AE and the ring current magnetic field (DR was investigated by observations obtained during the magnetic storm on 1-3 April 1973. During the storm main phase the DR development is accompanied by a shift of the auroral electrojets toward the equator. As a result, the standard AE indices calculated on the basis of data from auroral observatories was substantially lower than the real values (AE'. To determine AE' during the course of a storm main phase data from subauroral magnetic observatories should be used. It is shown that the intensity of the indices (AE' which take into account the shift of the electrojets is increased substantially relative to the standard indices during the storm main phase. AE' values are closely correlated with geoeffective solar wind parameters. A high correlation was obtained between AE' and the energy flux into the ring current during the storm main phase. Analysis of magnetic field variations during intervals with intense southward IMF components demonstrates a decrease of the saturation effect of auroral electrojet currents if subauroral stations magnetic field variations are taken into account. This applies both to case studies and statistical data. The dynamics of the electrojets in connection with the development of the ring current and of magnetospheric substorms can be described by the presence (absence of saturation for minimum (maximum AE index values during a 1-h interval. The ring current magnetic field asymmetry (ASY was calculated as the difference between the maximum and minimum field values along a parallel of latitude at low latitudes. The ASY value is closely correlated with geoeffective solar wind parameters and simultaneously is a more sensitive indicator of IMF Bz variations than the symmetric ring current. ASY increases (decreases faster during the main phase (the recovery phase than DR. The magnetic field decay at low latitudes in the

High-current proton accelerators-meson factories

International Nuclear Information System (INIS)

Dmitrievskij, V.P.

1979-01-01

A possibility of usage of accelerators of neutron as well as meson factories is considered. Parameters of linear and cyclic accelerators are given, which are employed as meson factories and as base for developing intense neutron generators. It is emphasized that the principal aim of developing neutron generators on the base of high current proton accelerators is production of intense neutron fluxes with a present energy spectrum. Production of tens-and-hundreds milliampere currents at the energy of 800-1000 MeV is considered at present for two types of accelerating facilities viz. linear accelerators under continuous operating conditions and cyclotrons with strong focusing. Quantitative evaluations of developing high-efficiency linear and cyclic accelerators are considered. The basic parameters of an ccelerating complex are given, viz. linear accelerator-injector and 800 MeV isochronous cyclotron. The main problems associated with their realization are listed [ru

Effects of decaying image currents on electron rings during compression between side walls and motion along conducting cylinders

International Nuclear Information System (INIS)

Herrmann, W.

1974-11-01

Decaying image currents consume energy which has to be supplied by the field producing electron ring. For very high currents (I > 10 3 A, particle number Ne > approximately 10 14 ) the losses become important and have to be included in the calculation of the ring dynamics. Special attention has been given to the focussing effects of the decaying image currents during compression and to the retarding force which develops when the ring is moved along a resistive cylinder. It is emphasized that in the latter case the ring experiences a 'run-away-situation', when the ratio of its velocity to the surface resistivity exceeds a certain limit. (orig.) [de

Status of experimental studies of electron cloud effects at the Los Alamos proton storage ring

International Nuclear Information System (INIS)

Macek, R.J.; Browman, A.A.; Borden, M.J.; Fitzgerald, D.H.; McCrady, R.C.; Spickermann, T.J.; Zaugg, T.J.

2004-01-01

Various electron cloud effects (ECE) including the two-stream (e-p) instability at the Los Alamos Proton Storage Ring (PSR) have been studied extensively for the past five years with the goal of understanding the phenomena, mitigating the instability and ultimately increasing beam intensity. The specialized diagnostics used in the studies are two types of electron detectors, the retarding field analyzer and the electron sweepmg detector - which have been employed to measure characteristics of the electron cloud as functions of time, location in the ring and various influential beam parameters - plus a short stripline beam position monitor used to measure high frequency motion of the beam centroid. Highlights of this research program are summarized along with more detail on recent results obtained since the ECLOUD'02 workshop. Recent work mcludes a number of parametric studies of the various factors that affect the electron cloud signals, studies of the sources of initial or 'seed' electrons, additional observations of electron cloud dissipation after the beam pulse is extracted, studies of the 'first pulse instability' issue, more data on electron suppression as a cure for the instability, and observations of the effect of a one-turn weak kick on intense beams in the presence of a significant electron cloud.

Novel dimeric bis(7)-tacrine proton-dependently inhibits NMDA-activated currents

International Nuclear Information System (INIS)

Luo, Jialie; Li, Wenming; Liu, Yuwei; Zhang, Wei; Fu, Hongjun; Lee, Nelson T.K.; Yu, Hua; Pang, Yuanping; Huang, Pingbo; Xia, Jun; Li, Zhi-Wang; Li, Chaoying; Han, Yifan

2007-01-01

Bis(7)-tacrine has been shown to prevent glutamate-induced neuronal apoptosis by blocking NMDA receptors. However, the characteristics of the inhibition have not been fully elucidated. In this study, we further characterize the features of bis(7)-tacrine inhibition of NMDA-activated current in cultured rat hippocampal neurons. The results show that with the increase of extracellular pH, the inhibitory effect decreases dramatically. At pH 8.0, the concentration-response curve of bis(7)-tacrine is shifted rightwards with the IC 50 value increased from 0.19 ± 0.03 μM to 0.41 ± 0.04 μM. In addition, bis(7)-tacrine shifts the proton inhibition curve rightwards. Furthermore, the inhibitory effect of bis(7)-tacrine is not altered by the presence of the NMDA receptor proton sensor shield spermidine. These results indicate that bis(7)-tacrine inhibits NMDA-activated current in a pH-dependent manner by sensitizing NMDA receptors to proton inhibition, rendering it potentially beneficial therapeutic effects under acidic conditions associated with stroke and ischemia

The storm time ring current dynamics and response to CMEs and CIRs using Van Allen Probes observations and CIMI simulations

Science.gov (United States)

Mouikis, Christopher; Bingham, Samuel; Kistler, Lynn; Spence, Harlan; Gkioulidou, Matina

2017-04-01

The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), and co-rotating interaction regions (CIR's). Using Van Allen Probes observations, we develop an empirical ring current model of the ring current pressure, the pressure anisotropy and the current density development during the storm phases for both types of storm drivers and for all MLTs inside L 6. Delineating the differences in the ring current development between these two drivers will aid our understanding of the ring current dynamics. We find that during the storm main phase most of the ring current pressure in the pre-midnight inner magnetosphere is contributed by particles on open drift paths that cause the development of a strong partial ring current that causes most of the main phase Dst drop. These particles can reach as deep as L 2 and their pressure compares to the local magnetic field pressure as deep as L 3. During the recovery phase, if these particles are not lost at the magnetopause, will become trapped and will contribute to the symmetric ring current. However, the largest difference between the CME and CIR ring current responses during the storm main and early recovery phases is caused by how the 15 - 60 keV O+ responds to these drivers. This empirical model is compared to the results of CIMI simulations of a CMEs and a CIRs where the model input is comprised of the superposed epoch solar wind conditions of the storms that comprise the empirical model. Different inner magnetosphere boundary conditions are tested in order to match the empirical model results. Comparing the model and simulation results improves our understanding of the ring current dynamics as part of the highly coupled inner magnetosphere system. In addition, within the framework of this empirical model, the prediction of the EMIC wave generation linear theory is tested using the observed plasma parameters and comparing with the observations of

Superconducting Magnet Technology for Future High Energy Proton Colliders

Science.gov (United States)

Gourlay, Stephen

2017-01-01

Interest in high field dipoles has been given a boost by new proposals to build a high-energy proton-proton collider to follow the LHC and programs around the world are taking on the task to answer the need. Studies aiming toward future high-energy proton-proton colliders at the 100 TeV scale are now being organized. The LHC and current cost models are based on technology close to four decades old and point to a broad optimum of operation using dipoles with fields between 5 and 12T when site constraints, either geographical or political, are not a factor. Site geography constraints that limit the ring circumference can drive the required dipole field up to 20T, which is more than a factor of two beyond state-of-the-art. After a brief review of current progress, the talk will describe the challenges facing future development and present a roadmap for moving high field accelerator magnet technology forward. This work was supported by the Director, Office of Science, High Energy Physics, US Department of Energy, under contract No. DE-AC02-05CH11231.

Modelling of the ring current in Saturn's magnetosphere

Directory of Open Access Journals (Sweden)

G. Giampieri

2004-01-01

Full Text Available The existence of a ring current inside Saturn's magnetosphere was first suggested by Smith et al. (1980 and Ness et al. (1981, 1982, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. Connerney et al. (1983 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set.

First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects.

Key words. Magnetospheric physics (current systems; planetary magnetospheres; plasma sheet

Observations of ions of ionospheric origin in the storm-time ring current

International Nuclear Information System (INIS)

Johnson, R.G.; Sharp, R.D.; Shelley, E.G.

1977-01-01

O + , He + , and H + ions in the energy range 0.5 to 16 keV have been observed in the storm-time ring current with an energetic ion mass spectrometer aboard the polar-orbiting S3-3 satellite. During the main phases of the 29 December 1976, 6 April 1977, and 19 April 1977 magnetic storms, the O + number density within the instrument energy range in the inner ring current (L=2.8--4.0) was larger than the H + density in the altitude range from about 5000--7000 km. At two days after the main phase of the 29 December 1976 storm, O + was still the dominant ion at MLT=14.5 hours in the L=2.6--3.4 range at altitudes near 6000 km

An experiment to study CP violation in the B system using an internal target at the HERA proton ring

International Nuclear Information System (INIS)

Hofmann, W.

1993-03-01

A group of physicists centered around the ARGUS collaboration got interested in hadron accelerators as a prolific source of B hadrons. The group is presently studying the option of a major-B-physics experiment to be performed at the HERA proton storage ring in fixed target mode using an internal target. Basic goal of the experiment is the detection of CP violation in the 'gold plated' B 0 → J/Ψ K s decay mode, using a dedicated detector triggered on lepton pairs from J/Ψ decay. (orig./HSI)

Access of energetic particles to storm time ring current through enhanced radial diffusion

International Nuclear Information System (INIS)

Lyons, L.R.; Schulz, M.

1989-01-01

Magnetic storms are distinguishable from other periods of geomagnetic activity by the injection of trapped electrons and ions to the 2 approx-lt L approx-lt 4 region. It has been proposed previously that this injection results from an inward displacement of the preexisting trapped-particle population by enhanced storm time electric fields. However, high-energy (approx-gt 40 keV) ring-current particles have drift periods that are typically shorter than the time of the main-phase development, and so the direct radial transport of these particles is restricted. The authors propose here that the transport of approx-gt 40 keV particles into the storm time ring current can result from enhanced stochastic radial transport driven by fluctuating electric fields during a storm's main phase. They estimate the effects of such electric fields by applying radial-diffusion theory, assuming a preexisting trapped-particle population as the initial conditions, and they demonstrate the feasibility of explaining observed flux increases of approx-gt 40-keV particles at L approx-lt 4 by enhanced radial diffusion. It is necessary that new particles be injected near the outer boundary of the trapping region so as to maintain the fluxes there as an outer boundary condition, and they estimate that the approx-gt 40-keV portion of the storm time ring current at L ∼ 3 consists of about 50% preexisting and about 50% new particles. They thus find that formation of the storm time ring current may be explainable via a combination of direct radial transport at energies approx-lt 40 keV and diffusive radial transport at higher energies

Ring Current He Ion Control by Bounce Resonant ULF Waves

Science.gov (United States)

Kim, Hyomin; Gerrard, Andrew J.; Lanzerotti, Louis J.; Soto-Chavez, Rualdo; Cohen, Ross J.; Manweiler, Jerry W.

2017-12-01

Ring current energy He ion (˜65 keV to ˜520 keV) differential flux data from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft show considerable variability during quiet solar wind and geomagnetic time periods. Such variability is apparent from orbit to orbit (˜9 h) of the spacecraft and is observed to be ˜50-100% of the nominal flux. Using data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument, also aboard the Van Allen Probes spacecraft, we identify that a dominant source of this variability is from ULF waveforms with periods of tens of seconds. These periods correspond to the bounce resonant timescales of the ring current He ions being measured by RBSPICE. A statistical survey using the particle and field data for one full spacecraft precession period (approximately 2 years) shows that the wave and He ion flux variations are generally anticorrelated, suggesting the bounce resonant pitch angle scattering process as a major component in the scattering of He ions.

Oscillatory persistent currents in self-assembled quantum rings.

Science.gov (United States)

Kleemans, N A J M; Bominaar-Silkens, I M A; Fomin, V M; Gladilin, V N; Granados, D; Taboada, A G; García, J M; Offermans, P; Zeitler, U; Christianen, P C M; Maan, J C; Devreese, J T; Koenraad, P M

2007-10-05

We report the direct measurement of the persistent current carried by a single electron by means of magnetization experiments on self-assembled InAs/GaAs quantum rings. We measured the first Aharonov-Bohm oscillation at a field of 14 T, in perfect agreement with our model based on the structural properties determined by cross-sectional scanning tunneling microscopy measurements. The observed oscillation magnitude of the magnetic moment per electron is remarkably large for the topology of our nanostructures, which are singly connected and exhibit a pronounced shape asymmetry.

SPL-based Proton Driver for a nu-Factory at CERN

CERN Document Server

Benedetto, E; Garoby, R; Meddahi, M

2010-01-01

The conceptual design and feasibility studies for a nu-Factory Proton Driver based on the CERN Superconducting Proton Linac (SPL) have been com- pleted. In the proposed scenario, the 4 MW proton beam (H- beam) is acceler- ated with the upgraded High Power (HP)-SPL to 5 GeV, stored in an accumu- lator ring and Þnally transported to a compressor ring, where bunch rotation takes place, in order to achieve the speciÞc time structure. We here summa- rize the choices in terms of lattice, magnet technology and RF manipulations in the two rings. The possible critical issues, such as heating of the foil for the charge-exchange injection, space-charge problems in the compressor and beam stability in the accumulator ring, have been addressed and are shown not to be show-stoppers. The analysis focuses on the baseline scenario, consider- ing 6 bunches in the accumulator, and preliminary studies are discussed for the option of 3 or a single bunch per burst.

ISAC target operation with high proton currents

CERN Document Server

Dombsky, M; Schmor, P; Lane, M

2003-01-01

The TRIUMF-ISAC facility target stations were designed for ISOL target irradiations with up to 100 mu A proton beam currents. Since beginning operation in 1998, ISAC irradiation currents have progressively increased from initial values of approx 1 mu A to present levels of up to 40 mu A on refractory metal foil targets. In addition, refractory carbide targets have operated at currents of up to 15 mu A for extended periods. The 1-40 mu A operational regime is achieved by tailoring each target to the thermal requirements dictated by material properties such as beam power deposition, thermal conductivity and maximum operating temperature of the target material. The number of heat shields on each target can be varied in order to match the effective emissivity of the target surface for the required radiative power dissipation. Targets of different thickness, surface area and volume have been investigated to study the effect of diffusion and effusion delays on the yield of radioisotopes. For yields of short-lived p...

Ionic ring current during magnetic disturbances according to observations at geostationary orbit

International Nuclear Information System (INIS)

Vlasova, N.A.; Kovtyukh, A.S.; Panasyuk, M.I.; Sosnovets, Eh.N.; Grafodanskij, O.S.; Islyaev, Sh.N.; Kozlov, A.G.

1988-01-01

Experimental data on variations of H + , (N,O) 2+ and (C,N,O) 4+ flows acquired at communication geostationary satellite GORIZONT (1985-07A) during and after weak magnetic disturbances (with amplitudes of D st -variations which are less than a few tens of nT) are analyzed. Dynamics of ion relative content is investigated. Change of ring current ionic composition within ∼ 50-120 keV/c energy range characterized by the increase of relative content of heavy ions of both solar and ionospheric origin was observed after two weak geomagnetic disturbances on 19-20.02 and 07.03.1985. Examples of disturbances where H + ions and (N,O) 2+ ionospheric ions are the main components of the injected ring current are presented along with the disturbances of such type

Ring current and auroral electrojets in connection with interplanetary medium parameters during magnetic storm

Directory of Open Access Journals (Sweden)

Y. I. Feldstein

Full Text Available The relationship between the auroral electrojet indices (AE and the ring current magnetic field (DR was investigated by observations obtained during the magnetic storm on 1-3 April 1973. During the storm main phase the DR development is accompanied by a shift of the auroral electrojets toward the equator. As a result, the standard AE indices calculated on the basis of data from auroral observatories was substantially lower than the real values (AE'. To determine AE' during the course of a storm main phase data from subauroral magnetic observatories should be used. It is shown that the intensity of the indices (AE' which take into account the shift of the electrojets is increased substantially relative to the standard indices during the storm main phase. AE' values are closely correlated with geoeffective solar wind parameters. A high correlation was obtained between AE' and the energy flux into the ring current during the storm main phase. Analysis of magnetic field variations during intervals with intense southward IMF components demonstrates a decrease of the saturation effect of auroral electrojet currents if subauroral stations magnetic field variations are taken into account. This applies both to case studies and statistical data. The dynamics of the electrojets in connection with the development of the ring current and of magnetospheric substorms can be described by the presence (absence of saturation for minimum (maximum AE index values during a 1-h interval. The ring current magnetic field asymmetry (ASY was calculated as the difference between the maximum and minimum field values along a parallel of latitude at low latitudes. The ASY value is closely correlated with geoeffective solar wind parameters and simultaneously is a more sensitive indicator of IMF B_z variations than the symmetric ring current.

Demonstration of electron clearing effect by means of a clearing electrode in high-intensity positron ring

International Nuclear Information System (INIS)

Suetsugu, Y.; Fukuma, H.; Wang, L.; Pivi, M.; Morishige, A.; Suzuki, Y.; Tsukamoto, M.; Tsuchiya, M.

2009-01-01

In the beam pipe of high-intensity positron/proton storage rings, undesired electron clouds may be first produced by photoelectrons and the ionization of residual gases; then the clouds increase by the secondary electron emission. In this study, a strip-line clearing electrode has been developed to mitigate the electron-cloud effect in high-intensity positron/proton storage rings. The electrode is composed of a thin tungsten layer with a thickness of 0.1 mm formed on a thin alumina ceramic layer with a thickness of 0.2 mm. The narrow alumina gap between the electrode and the beam pipe decreases the beam impedance and also enhances the heat transfer from the electrode to the beam pipe. A test model has been installed in the KEK B-factory (KEKB) positron ring, along with an electron monitor with a retarding grid. The electron density in a field free region decreased by one order of magnitude was observed on the application of ±500 V to the electrode at a beam current of 1.6 A with 1585 bunches. The reduction in the electron density was more drastic in a vertical magnetic field of 0.77 T, that is, the electron density decreased by several orders by applying +500 V to the electrode at the same beam current. This experiment is the first experiment demonstrating the principle of the clearing electrode that is used to mitigate the electron-cloud effect in a positron ring.

Effects of Uncertainties in Electric Field Boundary Conditions for Ring Current Simulations

Science.gov (United States)

Chen, Margaret W.; O'Brien, T. Paul; Lemon, Colby L.; Guild, Timothy B.

2018-01-01

Physics-based simulation results can vary widely depending on the applied boundary conditions. As a first step toward assessing the effect of boundary conditions on ring current simulations, we analyze the uncertainty of cross-polar cap potentials (CPCP) on electric field boundary conditions applied to the Rice Convection Model-Equilibrium (RCM-E). The empirical Weimer model of CPCP is chosen as the reference model and Defense Meteorological Satellite Program CPCP measurements as the reference data. Using temporal correlations from a statistical analysis of the "errors" between the reference model and data, we construct a Monte Carlo CPCP discrete time series model that can be generalized to other model boundary conditions. RCM-E simulations using electric field boundary conditions from the reference model and from 20 randomly generated Monte Carlo discrete time series of CPCP are performed for two large storms. During the 10 August 2000 storm main phase, the proton density at 10 RE at midnight was observed to be low (Dst index is bounded by the simulated Dst values. In contrast, the simulated Dst values during the recovery phases of the 10 August 2000 and 31 August 2005 storms tend to underestimate systematically the observed late Dst recovery. This suggests a need to improve the accuracy of particle loss calculations in the RCM-E model. Application of this technique can aid modelers to make efficient choices on either investing more effort on improving specification of boundary conditions or on improving descriptions of physical processes.

Electric dipole moment planning with a resurrected BNL Alternating Gradient Synchrotron electron analog ring

Directory of Open Access Journals (Sweden)

Richard M. Talman

2015-07-01

Full Text Available There has been much recent interest in directly measuring the electric dipole moments (EDM of the proton and the electron, because of their possible importance in the present day observed matter/antimatter imbalance in the Universe. Such a measurement will require storing a polarized beam of “frozen spin” particles, 15 MeV electrons or 230 MeV protons, in an all-electric storage ring. Only one such relativistic electric accelerator has ever been built—the 10 MeV “electron analog” ring at Brookhaven National Laboratory in 1954; it can also be referred to as the “AGS analog” ring to make clear it was a prototype for the Alternating Gradient Synchrotron (AGS proton ring under construction at that time at BNL. (Its purpose was to investigate nonlinear resonances as well as passage through “transition” with the newly invented alternating gradient proton ring design. By chance this electron ring, long since dismantled and its engineering drawings disappeared, would have been appropriate both for measuring the electron EDM and to serve as an inexpensive prototype for the arguably more promising, but 10 times more expensive, proton EDM measurement. Today it is cheaper yet to “resurrect” the electron analog ring by simulating its performance computationally. This is one purpose for the present paper. Most existing accelerator simulation codes cannot be used for this purpose because they implicitly assume magnetic bending. The new ual/eteapot code, described in detail in an accompanying paper, has been developed for modeling storage ring performance, including spin evolution, in electric rings. Illustrating its use, comparing its predictions with the old observations, and describing new expectations concerning spin evolution and code performance, are other goals of the paper. To set up some of these calculations has required a kind of “archeological physics” to reconstitute the detailed electron analog lattice design from a

Analogue Between Dynamic Hamiltonian-Operators of a Mesoscopic Ring Carrying Persistent Current and a Josephson Junction

International Nuclear Information System (INIS)

Fan Hongyi; Wang Jisuo

2006-01-01

By making the analogy between the operator Hamiltonians of a mesoscopic ring carrying the persistent current and a Josephson junction we have introduced a phase operator and entangled state representation to establish a theoretical formalism for the ring system.

Electron Cloud Generation and Trapping in a Quadrupole Magnet at the Los Alamos Proton Storage Ring

International Nuclear Information System (INIS)

Macek, Robert J.; Browman, Andrew A.; Ledford, John E.; TechSource, Santa Fe; Los Alamos; Borden, Michael J.; O'Hara, James F.; McCrady, Rodney C.; Rybarcyk, Lawrence J.; Spickermann, Thomas; Zaugg, Thomas J.; Pivi, Mauro T.F.

2008-01-01

Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the 'prompt' electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the 'swept' electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100 (micro)s. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole

Electron cloud generation and trapping in a quadrupole magnet at the Los Alamos proton storage ring

Directory of Open Access Journals (Sweden)

Robert J. Macek

2008-01-01

Full Text Available Recent beam physics studies on the two-stream e-p instability at the LANL proton storage ring (PSR have focused on the role of the electron cloud generated in quadrupole magnets where primary electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies using this diagnostic show that the “prompt” electron flux striking the wall in a quadrupole is comparable to the prompt signal in the adjacent drift space. In addition, the “swept” electron signal, obtained using the sweeping feature of the diagnostic after the beam was extracted from the ring, was larger than expected and decayed slowly with an exponential time constant of 50 to 100  μs. Other measurements include the cumulative energy spectra of prompt electrons and the variation of both prompt and swept electron signals with beam intensity. Experimental results were also obtained which suggest that a good fraction of the electrons observed in the adjacent drift space for the typical beam conditions in the 2006 run cycle were seeded by electrons ejected from the quadrupole.

Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

International Nuclear Information System (INIS)

Alexeyev, C. N.; Volyar, A. V.; Yavorsky, M. A.

2011-01-01

We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over the array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.

Energy transfer, orbital angular momentum, and discrete current in a double-ring fiber array

Energy Technology Data Exchange (ETDEWEB)

Alexeyev, C. N.; Volyar, A. V. [Taurida National V.I. Vernadsky University, Vernadsky Prospekt, 4, Simferopol, 95007, Crimea (Ukraine); Yavorsky, M. A. [Taurida National V.I. Vernadsky University, Vernadsky Prospekt, 4, Simferopol, 95007, Crimea (Ukraine); Universite Bordeaux and CNRS, LOMA, UMR 5798, FR-33400 Talence (France)

2011-12-15

We study energy transfer and orbital angular momentum of supermodes in a double-ring array of evanescently coupled monomode optical fibers. The structure of supermodes and the spectra of their propagation constants are obtained. The geometrical parameters of the array, at which the energy is mostly confined within the layers, are determined. The developed method for finding the supermodes of concentric arrays is generalized for the case of multiring arrays. The orbital angular momentum carried by a supermode of a double-ring array is calculated. The discrete lattice current is introduced. It is shown that the sum of discrete currents over the array is a conserved quantity. The connection of the total discrete current with orbital angular momentum of discrete optical vortices is made.

Simulations of plasma heating caused by the coalescence of multiple current loops in a proton-boron fusion plasma

International Nuclear Information System (INIS)

Haruki, T.; Yousefi, H. R.; Sakai, J.-I.

2010-01-01

Two dimensional particle-in-cell simulations of a dense plasma focus were performed to investigate a plasma heating process caused by the coalescence of multiple current loops in a proton-boron-electron plasma. Recently, it was reported that the electric field produced during the coalescence of two current loops in a proton-boron-electron plasma heats up all plasma species; proton-boron nuclear fusion may therefore be achievable using a dense plasma focus device. Based on this work, the coalescence process for four and eight current loops was investigated. It was found that the return current plays an important role in both the current pinch and the plasma heating. The coalescence of four current loops led to the breakup of the return current from the pinched plasma, resulting in plasma heating. For the coalescence of eight current loops, the plasma was confined by the pinch but the plasma heating was smaller than the two and four loop cases. Therefore the heating associated with current loop coalescence depends on the number of initial current loops. These results are useful for understanding the coalescence of multiple current loops in a proton-boron-electron plasma.

Polarized proton beams

International Nuclear Information System (INIS)

Roser, T.

1995-01-01

The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders

High current, high energy proton beams accelerated by a sub-nanosecond laser

Czech Academy of Sciences Publication Activity Database

Margarone, Daniele; Krása, Josef; Picciotto, A.; Torrisi, L.; Láska, Leoš; Velyhan, Andriy; Prokůpek, Jan; Ryc, L.; Parys, P.; Ullschmied, Jiří; Rus, Bedřich

2011-01-01

Roč. 653, č. 1 (2011), s. 159-163 ISSN 0168-9002 R&D Projects: GA ČR(CZ) GAP205/11/1165; GA AV ČR IAA100100715; GA MŠk(CZ) 7E09092 EU Projects: European Commission(XE) 212105 - ELI-PP Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20430508 Keywords : laser-acceleration * proton beam * high ion current * time -of-flight * proton energy distribution Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.207, year: 2011

Optimal conditions for high current proton irradiations at the university of Wisconsin's ion beam laboratory

International Nuclear Information System (INIS)

Wetteland, C. J.; Field, K. G.; Gerczak, T. J.; Eiden, T. J.; Maier, B. R.; Albakri, O.; Sridharan, K.; Allen, T. R.

2013-01-01

The National Electrostatics Corporation's (NEC) Toroidal Volume Ion Source (TORVIS) source is known for exceptionally high proton currents with minimal service downtime as compared to traditional sputter sources. It has been possible to obtain over 150μA of proton current from the source, with over 70μA on the target stage. However, beam fluxes above ∼1×10 17 /m2-s may have many undesirable effects, especially for insulators. This may include high temperature gradients at the surface, sputtering, surface discharge, cracking or even disintegration of the sample. A series of experiments were conducted to examine the role of high current fluxes in a suite of ceramics and insulating materials. Results will show the optimal proton irradiation conditions and target mounting strategies needed to minimize unwanted macro-scale damage, while developing a procedure for conducting preliminary radiation experiments.

Review of the Fermilab main ring accelerator study program as directed to the pp program

International Nuclear Information System (INIS)

Griffin, J.E.; MacLachlan, J.A.; Bridges, J.F.

1981-01-01

Recently the colliding beam goals at Fermilab have been redirected toward 2 TeV c.m. pp physics to be done in the Tevatron. The booster-main ring complex will be the proton injector and the source of protons for anti-proton production. Consequently, the emphasis of recent studies in the main ring has been directed at those problems which arise from the beam manipulation necessary for the pp scenario. These studies are divided into three categories: 1) true storage studies directed toward revealing problems and techniques likely to apply to storage in the Tevatron, 2) beam manipulations necessary for the production of anti-protons, and 3) beam manipulations necessary for producing single proton bunches containing 10/sup 11/ protons each. 16 refs

Polarized proton collider at RHIC

International Nuclear Information System (INIS)

Alekseev, I.; Allgower, C.; Bai, M.; Batygin, Y.; Bozano, L.; Brown, K.; Bunce, G.; Cameron, P.; Courant, E.; Erin, S.; Escallier, J.; Fischer, W.; Gupta, R.; Hatanaka, K.; Huang, H.; Imai, K.; Ishihara, M.; Jain, A.; Lehrach, A.; Kanavets, V.; Katayama, T.; Kawaguchi, T.; Kelly, E.; Kurita, K.; Lee, S.Y.; Luccio, A.; MacKay, W.W.; Mahler, G.; Makdisi, Y.; Mariam, F.; McGahern, W.; Morgan, G.; Muratore, J.; Okamura, M.; Peggs, S.; Pilat, F.; Ptitsin, V.; Ratner, L.; Roser, T.; Saito, N.; Satoh, H.; Shatunov, Y.; Spinka, H.; Syphers, M.; Tepikian, S.; Tominaka, T.; Tsoupas, N.; Underwood, D.; Vasiliev, A.; Wanderer, P.; Willen, E.; Wu, H.; Yokosawa, A.; Zelenski, A.N.

2003-01-01

In addition to heavy ion collisions (RHIC Design Manual, Brookhaven National Laboratory), RHIC will also collide intense beams of polarized protons (I. Alekseev, et al., Design Manual Polarized Proton Collider at RHIC, Brookhaven National Laboratory, 1998, reaching transverse energies where the protons scatter as beams of polarized quarks and gluons. The study of high energy polarized protons beams has been a long term part of the program at BNL with the development of polarized beams in the Booster and AGS rings for fixed target experiments. We have extended this capability to the RHIC machine. In this paper we describe the design and methods for achieving collisions of both longitudinal and transverse polarized protons in RHIC at energies up to √s=500 GeV

Vortex-ring-fractal Structure of Atom and Molecule

International Nuclear Information System (INIS)

Osmera, Pavel

2010-01-01

This chapter is an attempt to attain a new and profound model of the nature's structure using a vortex-ring-fractal theory (VRFT). Scientists have been trying to explain some phenomena in Nature that have not been explained so far. The aim of this paper is the vortex-ring-fractal modeling of elements in the Mendeleev's periodic table, which is not in contradiction to the known laws of nature. We would like to find some acceptable structure model of the hydrogen as a vortex-fractal-coil structure of the proton and a vortex-fractal-ring structure of the electron. It is known that planetary model of the hydrogen atom is not right, the classical quantum model is too abstract. Our imagination is that the hydrogen is a levitation system of the proton and the electron. Structures of helium, oxygen, and carbon atoms and a hydrogen molecule are presented too.

Studies of Beam Dynamics in Cooler Rings

International Nuclear Information System (INIS)

Dietrich, J.; Stein, J.; Meshkov, I.; Sidorin, A.; Smirnov, A.

2006-01-01

This report describes the numerical simulation of the crystalline proton beam formation in COSY using BETACOOL code. The study includes the description of experimental results at NAP-M storage ring where the large reduction of the momentum spread was observed for first time. The present simulation shows that this behavior of proton beam can not be explained as ordered state of protons. The numerical simulation of crystalline proton beams was done for COSY parameters. The number of protons when the ordering state can be observed is limited by value 106 particles and momentum spread less then 10-6. Experimental results for the attempt to achieve of ordered state of proton beam for COSY is presented. This work is supported by RFBR grant no. 05-02-16320 and INTAS grant no. 03-54-5584

An Ionosphere/Magnetosphere Coupling Current System Located in the Gap Between Saturn and its Rings

Science.gov (United States)

Khurana, K. K.; Dougherty, M. K.; Cao, H.; Hunt, G. J.; Provan, G.

2017-12-01

The Grand Finale Orbits of the Cassini spacecraft traversed through Saturn's D ring and brought the spacecraft to within 3000 km of Saturn's cloud tops. The closest approaches (CA) were near the equatorial plane of Saturn and were distributed narrowly around the local noon. The difference field (observations - internal field - magnetospheric ring current field) obtained from the Grand Finale orbits show persistent residual fields centered around the CA which diminish at higher latitudes on field lines that connect to the ring. Modeling of this perturbation in terms of internal harmonics shows that the perturbation is not of internal origin but is produced by external currents that couple the ionosphere to the magnetosphere. The sense of the current system suggests that the southern feet of the field lines in the ionosphere lead their northern footprints. We show that the observed field perturbations are consistent with a meridional Pedersen current whose strength is 1 MA/radian, i.e. comparable in strength to the Planetary-period-oscillation related current systems observed in the auroral zone. We show that the implied Lorentz force in the ionosphere extracts momentum from the faster moving southern ionosphere and passes it on to the northern ionosphere. We discuss several ideas for generating this current system. In particular, we highlight a mechanism that involves shears in the neutral winds in the thermospheric region to generate the observed magnetic field.

Dynamic aperture and transverse proton diffusion in HERA

International Nuclear Information System (INIS)

Zimmermann, F.

1994-04-01

The dynamic aperture caused by persistent-current nonlinear field errors is an important concern in the design of superconducting hadron storage rings. The HERA proton ring is the second superconducting accelerator in operation. In this lecture note, its measured dynamic aperture is compared with that inferred from comprehensive trackig studies. To understand the difference between prediction and measurement, a semi-analytical method is developed for evaluating transverse diffusion rates due to various processes, such as modulational diffusion or sweeping diffusion this analysis makes use of parameters for high-order resonances in the transverse phase space, which are obtained by normal-form algorithms using differential-algebra software. This semi-analytical results are consistent wit the measurements, and suggest that the actual dynamic aperture is caused by an interplay of tune modulation and nonlinear magnetic fields

Proceedings of the 1979 workshop on beam current limitations in storage rings, July 16-27, 1979

International Nuclear Information System (INIS)

Pellegrini, C.

1979-01-01

The Workshop on Beam Current Limitations in Storage Rings was held at Brookhaven National Laboratory from July 16 to 27, 1979. The purpose of this Workshop was to discuss the physical mechanisms limiting the beam current or current density in accelerators or storage rings. Many of these machines are now being built or planned for a variety of applications, such as colliding beam experiments, synchrotron light production, heavy ion beams. This diversity was reflected in the Workshop and in the papers which have been contributed to these Proceedings. The twenty-one papers from the workshop were incorporated individually in the data base

Critical current measurement in superconducting rings using an automatic inductive technique

International Nuclear Information System (INIS)

Gonzalez-Jorge, H.; Linares, B.; Quelle, I.; Carballo, E.; Romani, L.; Domarco, G.

2007-01-01

A measurement technique was developed to identify the critical current of superconducting rings. It is based on the detection of the voltage on a secondary coil when the current induced in the superconductor by a primary one go beyond to the critical value. The technique uses a DC power supply to control the AC current circulating by the primary circuit. Such circuit mainly consists on an AC power supply which gives a constant AC voltage, a primary inducting coil and a control coil with iron core. The AC current circulating by this circuit is modified with the change in the impedance of the control coil due to the fact of the DC current supplied by the power supply in parallel with it

Histidine in Continuum Electrostatics Protonation State Calculations

Science.gov (United States)

Couch, Vernon; Stuchebruckhov, Alexei

2014-01-01

A modification to the standard continuum electrostatics approach to calculate protein pKas which allows for the decoupling of histidine tautomers within a two state model is presented. Histidine with four intrinsically coupled protonation states cannot be easily incorporated into a two state formalism because the interaction between the two protonatable sites of the imidazole ring is not purely electrostatic. The presented treatment, based on a single approximation of the interrelation between histidine’s charge states, allows for a natural separation of the two protonatable sites associated with the imidazole ring as well as the inclusion of all protonation states within the calculation. PMID:22072521

Nonlinear interaction of colliding beams in particle storage rings

International Nuclear Information System (INIS)

Herrera, J.C.; Month, M.

1979-01-01

When two beams of high energy particles moving in opposite directions are brought into collision, a large amount of energy is available for the production of new particles. However to obtain a sufficiently high event rate for rare processes, such as the production of the intermediate vector boson (Z 0 and W +- ), large beam currents are also required. Under this circumstance, the high charge density of one beam results in a classical electromagnetic interaction on the particles in the other beam. This very nonlinear space charge force, caled the beam-beam force, limits the total circulating charge and, thereby, the ultimate performance of the colliding ring system. The basic nature of the beam-beam force is discussed, indicating how it is quite different in the case of continuous beams, which cross each other at an angle as compared to the case of bunched beams which collide head-on. Some experimental observations on the beam-beam interaction in proton-proton and electron-positron beams are then reviewed and interpreted. An important aspect of the beam-beam problem in storage rings is to determine at what point in the analysis of the particle dynamics is it relevant to bring in the concepts of stochasticity, slow diffusion, and resonance overlap. These ideas are briefly discussed

Proton-air and proton-proton cross sections

Directory of Open Access Journals (Sweden)

Ulrich Ralf

2013-06-01

Full Text Available Different attempts to measure hadronic cross sections with cosmic ray data are reviewed. The major results are compared to each other and the differences in the corresponding analyses are discussed. Besides some important differences, it is crucial to see that all analyses are based on the same fundamental relation of longitudinal air shower development to the observed fluctuation of experimental observables. Furthermore, the relation of the measured proton-air to the more fundamental proton-proton cross section is discussed. The current global picture combines hadronic proton-proton cross section data from accelerator and cosmic ray measurements and indicates a good consistency with predictions of models up to the highest energies.

Dynamics of Ring Current and Electric Fields in the Inner Magnetosphere During Disturbed Periods: CRCM-BATS-R-US Coupled Model

Science.gov (United States)

Buzulukova, N.; Fok, M.-C.; Pulkkinen, A.; Kuznetsova, M.; Moore, T. E.; Glocer, A.; Brandt, P. C.; Toth, G.; Rastaetter, L.

2010-01-01

We present simulation results from a one-way coupled global MHD model (Block-Adaptive-Tree Solar-Wind Roe-Type Upwind Scheme, BATS-R-US) and kinetic ring current models (Comprehensive Ring Current Model, CRCM, and Fok Ring Current, FokRC). The BATS-R-US provides the CRCM/FokRC with magnetic field information and plasma density/temperature at the polar CRCM/FokRC boundary. The CRCM uses an electric potential from the BATS-R-US ionospheric solver at the polar CRCM boundary in order to calculate the electric field pattern consistent with the CRCM pressure distribution. The FokRC electric field potential is taken from BATS-R-US ionospheric solver everywhere in the modeled region, and the effect of Region II currents is neglected. We show that for an idealized case with southward-northward-southward Bz IMF turning, CRCM-BATS-R-US reproduces well known features of inner magnetosphere electrodynamics: strong/weak convection under the southward/northward Bz; electric field shielding/overshielding/penetration effects; an injection during the substorm development; Subauroral Ion Drift or Polarization Jet (SAID/PJ) signature in the dusk sector. Furthermore, we find for the idealized case that SAID/PJ forms during the substorm growth phase, and that substorm injection has its own structure of field-aligned currents which resembles a substorm current wedge. For an actual event (12 August 2000 storm), we calculate ENA emissions and compare with Imager for Magnetopause-to-Aurora Global Exploration/High Energy Neutral Atom data. The CRCM-BATS-R-US reproduces both the global morphology of ring current and the fine structure of ring current injection. The FokRC-BATS-R-US shows the effect of a realistic description of Region II currents in ring current-MHD coupled models.

Studies Performed in Preparation for the Spallation Neutron Source Accumulator Ring Commissioning

CERN Document Server

Cousineau, Sarah M; Henderson, Stuart; Holmes, Jeffrey Alan; Plum, Michael

2005-01-01

The Spallation Neutron Source accumulator ring will compress 1.5?1014, 1 GeV protons from a 1 ms bunch train to a single 695 ns proton bunch for use in neutron spallation. Due to the high beam power, unprecedented control of beam loss will be required in order to control radiation and allow for hands-on maintenance in most areas of the ring. A number of detailed investigations have been performed to understand the primary sources of beam loss and to predict and mitigate problems associated with radiation hot spots in the ring. The ORBIT particle tracking code is used to perform realistic simulations of the beam accumulation in the ring, including detailed modeling of the injection system, transport through the measured magnet fields including higher order multipoles, and beam loss and collimation. In this paper we present the results of a number of studies performed in preparation for the 2006 commissioning of the accumulator ring.

Some topics in beam dynamics of storage rings

International Nuclear Information System (INIS)

Mais, H.

1996-06-01

In the following report we want to review some beam dynamics problems in accelerator physics. Theoretical tools and methods are introduced and discussed, and it is shown how these concepts can be applied to the study of various problems in storage rings. The first part treats Hamiltonian systems (proton accelerators) whereas the second part is concerned with explicitly stochastic systems (e.g. electron storage rings). (orig.)

The AGS Booster main ring power supply system

International Nuclear Information System (INIS)

Soukas, A.; Hughes, K.; Sandberg, J.; Toldo, F.; Zhang, S.Y.

1989-01-01

The AGS Booster is being designed as a very versatile particle accelerator. Its primary function is to be a high quality injector to the currently operating Alternating Gradient Synchrotron (AGS). The Booster/AGS combination will produce proton intensities greater than 5 x 10 13 protons per pulse (ppp), and accelerate heavy ions, with mass up to 200, to a maximum energy of 15 GeV per atomic mass unit (GeV/amu). The power supply for the Booster Main Ring (BMRPS) has to accommodate a wide range of cycles and a wide range of operating parameters. The cycles range from storage for several seconds to rapid cycling at 7.5 Hz. The peak output power is 18 MW. This paper will describe the AGS Booster machine powering requirements, the choice of power supply, the a.c. circuit tie-in and its associated problems and some of the details of the design of the BMRPS. 9 refs., 2 figs

The PEP [positron-electron-proton] electron-positron ring: An update

International Nuclear Information System (INIS)

1975-03-01

The first stage of the positron-electron-protron (PEP) colliding-beam system, which has been under joint study by a Lawrence Berkeley Laboratory--Stanford Linear Accelerator Center team for the past two years, will be the electron-positron storage ring. The physics justification for the e + e/sup /minus// ring is summarized briefly and the proposed facility is described. The ring will have six arcs having gross radii of about 220 m and six interaction regions located at the centers of straight sections about 130 m long. The longitudinal distance left free for experimental apparatus around the interaction regions was set provisionally at 20 m. The range of operating beam energies will be from 5 GeV to 15 GeV. The design luminosity at 15 GeV will be 10 32 cm/sup /minus/2/s/sup /minus/1/, and the luminosity will vary approximately as the square of the beam energy. Alternative methods under consideration for adjusting the beam cross section are discussed. The designs of the storage ring subsystems and of the conventional facilities including the experimental halls at the interaction regions are described. 7 figs., 3 tabs

Rates and energetics of tyrosine ring flips in yeast iso-2-cytochrome c

International Nuclear Information System (INIS)

Nall, B.T.; Zuniga, E.H.

1990-01-01

Isotope-edited nuclear magnetic resonance spectroscopy is used to monitor ring flip motion of the five tyrosine side chains in the oxidized and reduced forms of yeast iso-2-cytochrome c. With specifically labeled protein purified from yeast grown on media containing [3,5- 13 C]tyrosine, isotope-edited one-dimensional proton spectra have been collected over a 5-55 degree C temperature range. The spectra allow selective observation of the 10 3,5 tyrosine ring proton resonances and, using a two-site exchange model, allow estimation of the temperature dependence of ring flip rates from motion-induced changes in proton line shapes. For the reduced protein, tyrosines II and IV are in fast exchange throughout the temperature range investigated, or lack resolvable differences in static chemical shifts for the 3,5 ring protons. Tyrosines I, III, and V are in sloe exchange at low temperatures and in fast exchange at high temperatures. Spectral simulations give flip rates for individual tyrosines in a range of one flip per second at low temperatures to thousands of flips per second at high temperatures. Eyring plots show that two of the tyrosines (I and III) have essentially the same activation parameters. Tentative sequence-specific assignments for the tyrosines in reduced iso-2 are suggested by comparison to horse cytochrome c. For oxidized iso-2, five resonances are observed at high temperatures, suggesting flip rates for all five tyrosines sufficient to average static chemical shift differences. At lower temperatures, there is evidence of intermediate and slow flipping for some of the rings

Sub-keV ring current ions as the tracer of substorm injection

Directory of Open Access Journals (Sweden)

M. Yamauchi

2006-03-01

Full Text Available The dynamics of the energy-latitude dispersed sub-keV trapped ions inside the ring current region, the so-called wedge-like dispersions structure, were statistically studied using Viking satellite data. Probabilities with/without these signatures at various local times in the dayside are obtained in terms of different time-lags from the substorm activity monitored by the AE index. The structure appears in the early morning sector within a few hours after the substorm, and it slowly propagates eastward while decaying with a time scale of several hours. The result qualitatively confirmed the previous model that the wedge-like dispersions are originated from past substorm-related plasma injections into the nightside ring current region, and that the dispersion is formed when these injected plasma slowly moves eastward to the dayside by the drift motion (E×B (eastward, grad-<|B| (westward, and curvature (westward drifts. However, the appearance of the structure is twice or three times faster than the model prediction, and some structure reaches even to the evening sector. The results indicate that the start location of the drift is not as far as midnight and that the drift speed is slightly faster than the model prediction. The former means that the substorm-related increase of hot plasma in the ring current region shifts or extends to the early morning sector for large substorms, and the latter means that the substantial electric field driving the sub-keV ion drift is slightly different from the model field. We also detected the evacuating effect starting right after the substorm (or storm onset. The electric field imposed in the dayside magnetosphere seems to remove the remainder of trapped ions.

A development plan for the Fermilab proton source

International Nuclear Information System (INIS)

Holmes, S. D.

1997-01-01

The present Fermilab Proton Source is composed of a 750 KV ion source, a 400 MeV Linac, and an 8 GeV Booster synchrotron. This facility currently provides proton beams at intensities up to 5 x 10 10 protons/bunch for injection into the Main Ring in support of the current Tevatron fixed target run. Following completion of the Main Injector project in 1999, the Proton Source is expected to provide protons to the Main Injector at an intensity of 6 x 10 10 protons/bunch as required to meet established performance goals for Tevatron Collider Run II. With the advent of the Main Injector the demand for protons in support of a diverse physics research program at Fermilab will grow. This is because the Main Injector creates a new capability for simultaneous operation of the collider and fixed target programs at 120 GeV. It has also been recently appreciated that a physics program based on the utilization of unallocated 8 GeV Booster cycles is potentially very attractive. A variety of experiments are either approved or under consideration including the Neutrinos at the Main Injector (NUMI) project, Kaons at the Main Injector (KAMI), and an rf separated K + beam for CPT tests, all utilizing 120 GeV protons, and a low energy neutrino (MiniBooNe) or muon program based on 8 GeV protons from the Booster. In addition significant effort is now being invested in defining paths to a factor of five improvement in Tevatron collider luminosity beyond those expected in Run II and in understanding the possible future siting of either a very large hadron collider or a modest energy ''First Muon Collider'' (FMC) at Fermilab. Support for these varied activities is beyond the capabilities of the current Proton Source--in the case of the FMC by about a factor of ten as measured in delivered protons per second. The purpose of this document is to describe a possible evolution of the Fermilab Proton Source over the next ten years. The goal is to outline a staged plan, with significant

Electron beam depolarization in a damping ring

International Nuclear Information System (INIS)

Minty, M.

1993-04-01

Depolarization of a polarized electron beam injected into a damping ring is analyzed by extending calculations conventionally applied to proton synchrotrons. Synchrotron radiation in an electron ring gives rise to both polarizing and depolarizing effects. In a damping ring, the beam is stored for a time much less than the time for self polarization. Spin flip radiation may therefore be neglected. Synchrotron radiation without spin flips, however, must be considered as the resonance strength depends on the vertical betatron oscillation amplitude which changes as the electron beam is radiation damped. An expression for the beam polarization at extraction is derived which takes into account radiation damping. The results are applied to the electron ring at the Stanford Linear Collider and are compared with numerical matrix formalisms

Proton induction linacs as high-intensity neutron sources

International Nuclear Information System (INIS)

Keefe, D.; Hoyer, E.

1981-01-01

Proton induction linacs are explored as high intensity neutron sources. The induction linac - concept, properties, experience with electrons, and possibilities - and its limitations for accelerating ions are reviewed. A number of proton induction linac designs are examined with the LIACEP program and general conclusions are given. Results suggest that a proton induction accelerator of the lowest voltage, consistent with good neutron flux, is preferred and could well be cost competitive with the usual rf linac/storage ring designs. (orig.)

An overview of current experiments in search of proton decay

International Nuclear Information System (INIS)

Goldhaber, M.; Sulak, L.R.

1981-01-01

Detectors being used in current experiments dedicated to the search for proton decay, fall into two classes, totally active water Cherenkov detectors with light collected by phototubes, and sampling calorimeters with particle ionization tracked by gas tube arrays. An example of each type is considered in detail, the features of other detectors in the two classes are pointed out and compared with those of the same type. (U.K.)

Adiabatic energization in the ring current and its relation to other source and loss terms

Science.gov (United States)

Liemohn, M. W.; Kozyra, J. U.; Clauer, C. R.; Khazanov, G. V.; Thomsen, M. F.

2002-04-01

The influence of adiabatic energization and deenergization effects, caused by particle drift in radial distance, on ring current growth rates and loss lifetimes is investigated. Growth and loss rates from simulation results of four storms (5 June 1991, 15 May 1997, 19 October 1998, and 25 September 1998) are examined and compared against the y component of the solar wind electric field (Ey,sw). Energy change rates with and without the inclusion of adiabatic energy changes are considered to isolate the influence of this mechanism in governing changes of ring current strength. It is found that the influence of adiabatic drift effects on the energy change rates is very large when energization and deenergization are considered separately as gain and loss mechanisms, often about an order of magnitude larger than all other source or loss terms combined. This is true not only during storm times, when the open drift path configuration of the hot ions dominates the physics of the ring current, but also during quiet times, when the small oscillation in L of the closed trajectories creates a large source and loss of energy each drift orbit. However, the net energy change from adiabatic drift is often smaller than other source and loss processes, especially during quiet times. Energization from adiabatic drift dominates ring current growth only during portions of the main phase of storms. Furthermore, the net-adiabatic energization is often positive, because some particles are lost in the inner magnetosphere before they can adiabatically deenergize. It is shown that the inclusion of only this net-adiabatic drift effect in the total source rate or loss lifetime (depending on the sign of the net-adiabatic energization) best matches the observed source and loss values from empirical Dst predictor methods (that is, for consistency, these values should be compared between the calculation methods). While adiabatic deenergization dominates the loss timescales for all Ey,sw values

Solar wind parameters responsible for the plasma injection into the magnetospheric ring current region

International Nuclear Information System (INIS)

Bobrov, M.S.

1977-01-01

Solar wind effect on the magnetospheric ring-current region has been considered. The correlations with solar wind parameters of the magnitude qsub(o) proportional to the total energy of particles being injected into the magnetospheric ring-current region per one hour are studied statistically and by comparison of time variations. The data on 8 sporadic geomagnetic storms of various intensity, from moderate to very severe one, are used. It is found that qsub(o) correlates not only with the magnitude and the direction of the solar-wind magnetic field component normal to the ecliptic plane, Bsub(z), but also with the variability, sigmasub(B), of the total magnetic-field strength vector. The solar-wind flux velocity ν influences the average storm intensity but the time variations of ν during any individual storm do not correlate with those of qsub(o)

Macroscopic ion acceleration associated with the formation of the ring current in the earth's magnetosphere

International Nuclear Information System (INIS)

Mauk, B.H.; Meng, C.I.

1986-01-01

As an illustration of the operation of macroscopic ion acceleration processes within the earth's magnetosphere, the paper reviews processes thought to be associated with the formation of the earth's ring-current populations. Arguing that the process of global, quasi-curl-free convection cannot explain particle characteristics observed in the middle (geosynchronous) to outer regions, it is concluded that the transport and energization of the seed populations that give rise to the ring-current populations come about in two distinct stages involving distinct processes. Near and outside the geostationary region, the energization and transport are always associated with highly impulsive and relatively localized processes driven by inductive electric fields. The subsequent adiabatic earthward transport is driven principally by enhanced, curl-free global convection fields. 58 references

The proton transfer reaction in malonaldehyde derivatives: Substituent effects and quasi-aromaticity of the proton bridge

International Nuclear Information System (INIS)

Palusiak, Marcin; Simon, Silvia; Sola, Miquel

2007-01-01

The proton transfer in malonaldehyde and in some of its derivatives have been considered in order to study the interrelation between the reaction barrier and the π-delocalization in the quasi-ring. A set of simple and mostly common substituents having different properties in resonance effect according to values of substituents constants were chosen in order to simulate the influence of substitution in position 2 or in position 1 (or 3) of malonaldehyde on the quasi-aromaticity and H-bonding. The following substituents have been taken into consideration: NO, NO 2 , CN, CHO, F, H, CH 3 , OCH 3 , OH, and NH 2 . Our results show that when the substituent is attached at position 2 of the quasi-ring, the resonance effect predominates over the field/inductive effect which leads to changes in H-bonding and quasi-aromaticity of the ring motif, while in the case of 1(3) substitution the field/inductive effect is significantly more effective influencing the HB strength, and thus, the proton transfer barrier. Somehow counterintuitively, for the 1(3) substituted systems, the most stable isomer is the one having the weakest HB and lower aromaticity. The reason for this surprising behaviour is discussed

A NEW RELATIVE PROTON POLARIMETER FOR RHIC

International Nuclear Information System (INIS)

HUANG, H.; ALEKSEEV, I.; BUNCE, G.; BRUNER, N.; DESHPANDE, A.; GOTO, Y.; FIELDS, D.; IMAI, K.

2001-01-01

An innovative polarimeter based on proton carbon elastic scattering in the Coulomb Nuclear Interference (CNI) region has been installed and commissioned in the Blue ring of RHIC during the first RHIC polarized proton commissioning in September, 2000. The polarimeter consists of ultra-thin carbon targets and four silicon detectors. All elements are in a 1.6 meter vacuum chamber. This paper summarizes the polarimeter design issues and recent commissioning results

Proton storage ring (PSR) diagnostics and control system

International Nuclear Information System (INIS)

Clout, P.

1983-01-01

When any new accelerator or storage ring is built that advances the state of the art, the diagnostic system becomes extremely important in tuning the facility to full specification. This paper will discuss the various diagnostic devices planned or under construction for the PSR and their connection into the control system

Measurement of pion, kaon and proton production in proton-proton collisions at $\\sqrt{s}$ = 7 TeV

CERN Document Server

Adam, Jaroslav; Aggarwal, Madan Mohan; Aglieri Rinella, Gianluca; Agnello, Michelangelo; Agrawal, Neelima; Ahammed, Zubayer; Ahmed, Ijaz; Ahn, Sang Un; Aimo, Ilaria; Aiola, Salvatore; Ajaz, Muhammad; Akindinov, Alexander; Alam, Sk Noor; Aleksandrov, Dmitry; Alessandro, Bruno; Alexandre, Didier; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Alme, Johan; Alt, Torsten; Altinpinar, Sedat; Altsybeev, Igor; Alves Garcia Prado, Caio; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshaeuser, Harald; Arcelli, Silvia; Armesto Perez, Nestor; Arnaldi, Roberta; Aronsson, Tomas; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bagnasco, Stefano; Bailhache, Raphaelle Marie; Bala, Renu; Baldisseri, Alberto; Ball, Markus; Baltasar Dos Santos Pedrosa, Fernando; Baral, Rama Chandra; Barbano, Anastasia Maria; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Ramillien Barret, Valerie; Bartalini, Paolo; Bartke, Jerzy Gustaw; Bartsch, Esther; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batista Camejo, Arianna; Batyunya, Boris; Batzing, Paul Christoph; Bearden, Ian Gardner; Beck, Hans; Bedda, Cristina; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bello Martinez, Hector; Bellwied, Rene; Belmont Iii, Ronald John; Belmont Moreno, Ernesto; Belyaev, Vladimir; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bertens, Redmer Alexander; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhat, Inayat Rasool; Bhati, Ashok Kumar; Bhattacharjee, Buddhadeb; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Biswas, Saikat; Bjelogrlic, Sandro; Blanco, Fernando; Blau, Dmitry; Blume, Christoph; Bock, Friederike; Bogdanov, Alexey; Boggild, Hans; Boldizsar, Laszlo; Bombara, Marek; Book, Julian Heinz; Borel, Herve; Borissov, Alexander; Borri, Marcello; Bossu, Francesco; Botje, Michiel; Botta, Elena; Boettger, Stefan; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Broker, Theo Alexander; Browning, Tyler Allen; Broz, Michal; Brucken, Erik Jens; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Buncic, Predrag; Busch, Oliver; Buthelezi, Edith Zinhle; Buxton, Jesse Thomas; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calero Diaz, Liliet; Caliva, Alberto; Calvo Villar, Ernesto; Camerini, Paolo; Carena, Francesco; Carena, Wisla; Castillo Castellanos, Javier Ernesto; Castro, Andrew John; Casula, Ester Anna Rita; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Chartier, Marielle; Charvet, Jean-Luc Fernand; Chattopadhyay, Subhasis; Chattopadhyay, Sukalyan; Chelnokov, Volodymyr; Cherney, Michael Gerard; Cheshkov, Cvetan Valeriev; Cheynis, Brigitte; Chibante Barroso, Vasco Miguel; Dobrigkeit Chinellato, David; Chochula, Peter; Choi, Kyungeon; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Colamaria, Fabio Filippo; Colella, Domenico; Collu, Alberto; Colocci, Manuel; Conesa Balbastre, Gustavo; Conesa Del Valle, Zaida; Connors, Megan Elizabeth; Contreras Nuno, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Crochet, Philippe; Cruz Albino, Rigoberto; Cuautle Flores, Eleazar; Cunqueiro Mendez, Leticia; Dahms, Torsten; Dainese, Andrea; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Supriya; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; De Caro, Annalisa; De Cataldo, Giacinto; 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Lea, Ramona; Leardini, Lucia; Lee, Graham Richard; Lee, Seongjoo; Legrand, Iosif; Lehnert, Joerg Walter; Lemmon, Roy Crawford; Lenti, Vito; Leogrande, Emilia; Leon Monzon, Ildefonso; Leoncino, Marco; Levai, Peter; Li, Shuang; Li, Xiaomei; Lien, Jorgen Andre; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Ljunggren, Hans Martin; Lodato, Davide Francesco; Lonne, Per-Ivar; Loggins, Vera Renee; Loginov, Vitaly; Loizides, Constantinos; Lokesh, Kumar; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lowe, Andrew John; Lu, Xianguo; Luettig, Philipp Johannes; Lunardon, Marcello; Luparello, Grazia; Maevskaya, Alla; Mager, Magnus; Mahajan, Sanjay; Mahmood, Sohail Musa; Maire, Antonin; Majka, Richard Daniel; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Liudmila; Mal'Kevich, Dmitry; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; 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Morreale, Astrid; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhlheim, Daniel Michael; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Mulligan, James Declan; Gameiro Munhoz, Marcelo; Murray, Sean; Musa, Luciano; Musinsky, Jan; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Naru, Muhammad Umair; Nattrass, Christine; Nayak, Kishora; Nayak, Tapan Kumar; Nazarenko, Sergey; Nedosekin, Alexander; Nellen, Lukas; Ng, Fabian; Nicassio, Maria; Niculescu, Mihai; Niedziela, Jeremi; Nielsen, Borge Svane; Nikolaev, Sergey; Nikulin, Sergey; Nikulin, Vladimir; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Norman, Jaime; Nyanin, Alexander; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Ohlson, Alice Elisabeth; Okatan, Ali; Okubo, Tsubasa; Olah, Laszlo; Oleniacz, Janusz; Oliveira Da Silva, Antonio Carlos; Oliver, Michael Henry; Onderwaater, Jacobus; Oppedisano, Chiara; Ortiz Velasquez, Antonio; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Ozdemir, Mahmut; Pachmayer, Yvonne Chiara; Pagano, Paola; Paic, Guy; Pajares Vales, Carlos; Pal, Susanta Kumar; Pan, Jinjin; Pant, Divyash; Papikyan, Vardanush; Pappalardo, Giuseppe; Pareek, Pooja; Park, Woojin; Parmar, Sonia; Passfeld, Annika; Paticchio, Vincenzo; Paul, Biswarup; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitry Yurevich; Perez Lara, Carlos Eugenio; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petrov, Viacheslav; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Planinic, Mirko; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polishchuk, Boris; Poljak, Nikola; Poonsawat, Wanchaloem; Pop, Amalia; Porteboeuf, Sarah Julie; Porter, R Jefferson; Pospisil, Jan; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puccio, Maximiliano; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Punin, Valery; Putschke, Jorn Henning; Qvigstad, Henrik; Rachevski, Alexandre; Raha, Sibaji; Rajput, Sonia; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Razazi, Vahedeh; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Reed, Rosi Jan; Rehman, Attiq Ur; Reichelt, Patrick Simon; Reicher, Martijn; Reidt, Felix; Ren, Xiaowen; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riabov, Viktor; Ricci, Renato Angelo; Richert, Tuva Ora Herenui; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Ristea, Catalin-Lucian; Rivetti, Angelo; Rocco, Elena; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roeed, Ketil; Rogochaya, Elena; Rohr, David Michael; Roehrich, Dieter; Romita, Rosa; Ronchetti, Federico; Ronflette, Lucile; Rosnet, Philippe; Rossi, Andrea; Roukoutakis, Filimon; Roy, Ankhi; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Ryabov, Yury; Rybicki, Andrzej; Sadovskiy, Sergey; Safarik, Karel; Sahlmuller, Baldo; Sahoo, Pragati; Sahoo, Raghunath; Sahoo, Sarita; Sahu, Pradip Kumar; Saini, Jogender; Sakai, Shingo; Saleh, Mohammad Ahmad; Salgado Lopez, Carlos Alberto; Salzwedel, Jai Samuel Nielsen; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Santagati, Gianluca; Sarkar, Debojit; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schuchmann, Simone; Schukraft, Jurgen; Schulc, Martin; Schuster, Tim Robin; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; 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2015-05-27

The measurement of primary $\\pi^{\\pm}$, K$^{\\pm}$, p and $\\overline{p}$ production at mid-rapidity ($|y| <$ 0.5) in proton-proton collisions at $\\sqrt{s} = 7$ TeV performed with ALICE (A Large Ion Collider Experiment) at the Large Hadron Collider (LHC) is reported. Particle identification is performed using the specific ionization energy loss and time-of-flight information, the ring-imaging Cherenkov technique and the kink-topology identification of weak decays of charged kaons. Transverse momentum spectra are measured from 0.1 up to 3 GeV/$c$ for pions, from 0.2 up to 6 GeV/$c$ for kaons and from 0.3 up to 6 GeV/$c$ for protons. The measured spectra and particle ratios are compared with QCD-inspired models, tuned to reproduce also the earlier measurements performed at the LHC. Furthermore, the integrated particle yields and ratios as well as the average transverse momenta are compared with results at lower collision energies.

Optimal conditions for high current proton irradiations at the university of Wisconsin's ion beam laboratory

Energy Technology Data Exchange (ETDEWEB)

Wetteland, C. J.; Field, K. G.; Gerczak, T. J. [Materials Science Program, University of Wisconsin, Madison, WI 53706 (United States); Eiden, T. J.; Maier, B. R.; Albakri, O.; Sridharan, K.; Allen, T. R. [Department of Engineering Physics, University of Wisconsin, Madison, WI 53706 (United States)

2013-04-19

The National Electrostatics Corporation's (NEC) Toroidal Volume Ion Source (TORVIS) source is known for exceptionally high proton currents with minimal service downtime as compared to traditional sputter sources. It has been possible to obtain over 150{mu}A of proton current from the source, with over 70{mu}A on the target stage. However, beam fluxes above {approx}1 Multiplication-Sign 10{sup 17}/m2-s may have many undesirable effects, especially for insulators. This may include high temperature gradients at the surface, sputtering, surface discharge, cracking or even disintegration of the sample. A series of experiments were conducted to examine the role of high current fluxes in a suite of ceramics and insulating materials. Results will show the optimal proton irradiation conditions and target mounting strategies needed to minimize unwanted macro-scale damage, while developing a procedure for conducting preliminary radiation experiments.

The control systems for the CERN Super Proton Synchrotron ring power supplies

CERN Document Server

Kuhn, H K

1981-01-01

The dedicated control system for the 16 voltage-controlled Main Ring pulsed supplies, allowing the reproduction of the desired B and Q fields to better than +or-2*10/sup -4/ at injection is described. It outlines both the hardware (smoothed function generators) and software side. Current measurements via DVMs or the B train off the reference magnets are used as inputs to the correction algorithm which is based on successive approximation. The algorithm enables the machine operators to trim selectively both the closed orbit and/or the betatron wave number of the machine within 1 to a few cycles. The control system related computer memory requirements are given. (0 refs).

The Role of Ionospheric O+ in Forming the Storm-time Ring Current

Science.gov (United States)

Kistler, L. M.; Mouikis, C.; Menz, A.; Bingham, S.

2017-12-01

During storm times, the particle pressure that creates the storm-time ring current in the inner magnetosphere can be dominated by O+. This is surprising, as the immediate source for the ring current is the nightside plasma sheet, and O+ is usually not the dominant species in the plasma sheet. In this talk we examine the many factors that lead to this result. The O+ outflow is enhanced during geomagnetically active times. The transport paths of O+ and H+ are different, such that the O+ that reaches the near-earth plasma sheet is more energetic than H+. The source spectrum in the near-earth plasma sheet can be harder for O+ than for H+, perhaps due to substorm injections, so that the more energetic plasma has a higher O+/H+ ratio. And finally the plasma sheet O+ can be more abundant towards the beginning of the storm, when the convection is largest, so the enhanced O+ is brought the deepest into the inner magnetosphere. We will discuss the interrelationships between these different effects as well as the ways in which O+ itself may influence the system.

Proton affinity of diastereoisomers of modified prolines using the kinetic method and density functional theory calculations: role of the cis/trans substituent on the endo/exo ring conformation.

Science.gov (United States)

Mezzache, S; Pepe, C; Karoyan, P; Fournier, F; Tabet, J-C

2005-01-01

The proton affinity (PA) of cis/trans-3-prolinoleucines and cis/trans-3-prolinoglutamic acids have been studied by the kinetic method and density functional theory (DFT) calculations. Several conformations of the neutral and the protonated modified prolines, in particular the endo and exo ring conformations, were analyzed with respect to their contribution to the PA values. When the substituent is an alkyl, both the diastereoisomers have the same PA value. However, the PA values for the diastereoisomers are different when the substituted chain contains functional groups (e.g. a carboxyl group). This variation in PA values could be attributed to the existence of intramolecular hydrogen bonds. Copyright (c) 2005 John Wiley & Sons, Ltd.

Sources and sinks of Earth's ring current populations

Science.gov (United States)

Mauk, B.

2017-12-01

Processes that modify and transport current-carrying particles into and out of Earth's ring current regions are overviewed and discussed here with a focus on outstanding mysteries and uncertainties. Examples of such mysteries include the following. Some modeling and observational approaches point to a need for storm-time enhancements in the global electric field configuration to help bring magnetotail populations into the inner magnetosphere. And yet, electric field measurements from several missions, most recently the Van Allen Probes, suggest that only highly transient enhancements occur in critical regions that connect the outer and inner regions. Global enhancements appear to be internally generated rather than necessarily being driven from the outside. Another sample mystery involves the processes that give rise to the sometimes initial prompt recovery of the magnetic storm indice DST, given that loss processes traditionally invoked are likely too slow. Wave losses, such as those engendered by Electromagnetic Ion Cyclotron (EMIC) waves, may be responsible, but observational support for such a solution is lacking. These and other uncertainties are discussed with a goal of addressing how they might be addressed with the present great constellation of Earth-orbiting spacecraft, most recently joined by MMS and Arase (ERG).

Vertical septum magnets for distributing the beam to the 4 PS Booster rings

CERN Multimedia

Ordan, Julien Marius

2017-01-01

To facilitate H- injection from Linac4 to the PS Booster via the transfer line the BI.SMV10 (Booster Injection Septum Magnet Vertical) provides the vertical deflection of the 160 MeV H- beam to rings 1, 2 and 4 of the Booster. Currently this system is capable of deflecting 50 MeV protons and comprises an assembly of ferrite type magnets in an “omega” section vacuum tank (see fig. 1). The current system shall be replaced with a UHV compatible vacuum chamber incorporating 3 sets of double septum magnets, pulsed from 3 individual power supplies via transformers with 12:1 ratio.

On the compressor ring for the JAERI neutron science project

Energy Technology Data Exchange (ETDEWEB)

Yamane, Isao [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

1997-11-01

(1), As long as a 1.5 GeV-8 MW linear accelerator is constructed in the JAERI neutron science center, it is quite reasonable to construct a 5 MW compressor ring as a driver of a high intensity spallation neutron source to generate pulsed neutron beams. (2), Suppression of beam loss around the compressor ring to an acceptable level is the most crucial subject to be coped with in designing a MW-class compressor ring. This subject should be successfully cleared by carefully studying and designing the overall system of accelerator and tunnel. (3), The `PSR instability` was comprehensively discussed in the NSNS workshop held at Santa Fe in March, 1997, as a remaining problem of a high intensity proton compressor ring. People of Los Alamos attributed it to an e-p instability. But some questions like the cause that makes some part of protons leak away from a beam bunch to a bunch gap are yet left open. (4), A new scheme of two step H{sup 0} injection is proposed to remove defects of the conventional one of Los Alamos PSR. (author)

ELECTRON CLOUD EFFECTS IN HIGH INTENSITY PROTON ACCELERATORS

International Nuclear Information System (INIS)

Wei, J.; Macek, R.J.

2002-01-01

One of the primary concerns in the design and operation of high-intensity proton synchrotrons and accumulators is the electron cloud and associated beam loss and instabilities. Electron-cloud effects are observed at high-intensity proton machines like the Los Alamos National Laboratory's PSR and CERN's SPS, and investigated experimentally and theoretically. In the design of next-generation high-intensity proton accelerators like the Spallation Neutron Source ring, emphasis is made in minimizing electron production and in enhancing Landau damping. This paper reviews the present understanding of the electron-cloud effects and presents mitigation measures

Measurements of fusion-protons anisotropy around the pinch axis within high-current PF-1000 experiments

Energy Technology Data Exchange (ETDEWEB)

Sadowski, M.J. [The Andrzej Soltan Institute for Nuclear Studies - IPJ, 05-400 Otwock-Swierk (Poland)] [Institute of Plasma Physics and Laser Microfusion - IPPLM, 01-497 Warsaw (Poland); Malinowska, A.; Malinowski, K.; Czaus, K.; Kwiatkowski, R.; Skladnik-Sadowska, E.; Zebrowski, J. [The Andrzej Soltan Institute for Nuclear Studies - IPJ, 05-400 Otwock-Swierk (Poland); Karpinski, L.; Paduch, M.; Scholz, M.; Stepniewski, W. [Institute of Plasma Physics and Laser Microfusion - IPPLM, 01-497 Warsaw (Poland)

2011-07-01

The paper describes measurements of fast protons produced by D-D fusion reactions during high-current discharges within the PF-1000 facility operated with the deuterium filling at 27 kV, 480 kJ. The measurements were performed by means of a set of pinhole-cameras equipped with PM-355 track detectors shielded by 80-{mu}m-thick Al-filters, which eliminated fast primary deuterons and protons of lower energy (< 3 MeV). Those cameras were placed at different angles around the pinch axis. The obtained proton images showed a distinct angular anisotropy, which was explained by an influence of local magnetic fields connected with a filamentary structure of the plasma column during the fast proton (and neutron) emission. The paper shows that in addition to measurements of a fusion neutron anisotropy it is reasonable to study also an anisotropy of fusion protons (originated from the second branch of the D-D reactions), as well as other charged fusion products. This document is composed of a paper followed by a poster

Progress on a prototype main ring rf cavity

International Nuclear Information System (INIS)

Swain, G.; Kandarian, R.; Thiessen, H.A.; Poirier, R.; Smythe, W.R.

1989-01-01

A prototype rf cavity and rf drive system for a hadron facility main ring has been designed and will be tested in the Proton Storage Ring (PSR) at Los Alamos as a part of a collaborative effort between LANL and TRIUMF. The cavity uses an orthogonally biased ferrite tuner. The design provides for accelerating gap voltages up to 200 kV for the 49.3 to 50.8 MHz range. Progress on the cavity construction and testing is described. 13 refs., 5 figs

Current and future applications of protons in medical imaging and treatment

Energy Technology Data Exchange (ETDEWEB)

Schulte, Reinhard W. [Loma Linda University Medical Center, CA (United States). Dept. of Radiation Medicine

2011-07-01

Protons have a more than 50-year history of applications in medical therapy and more recently also in imaging. Therapy with protons became possible after proton accelerators capable of accelerating protons to energies higher than 150 MeV had been built during the 1940s in a few places around the world. Proton radiography experiments started at the Harvard Cyclotron in the early 1960s. Physicist Allan Cormack, who shared the Nobel Prize for laying the foundation of computed tomography together with Sir Godfrey Hounsfield in 1979, suggested that protons can be used for tomographic imaging for the first time in 1963. Proton CT requires a rotating proton gantry, which did not become available until 1991, at our institution. The interest in proton CT has been renewed due to the fact that exact proton treatment planning is only possible with accurate knowledge of the relative proton stopping power distribution (with respect to water) of the patient, which is best derived by using protons for imaging. Early attempts to do proton CT were hampered by the lack of high-resolution particle trackers, fast data acquisition electronics, and sufficient computing power. Also, efficient proton CT reconstruction algorithms had to be developed that can handle reconstruction based on a large number of proton histories, taking into account the non-straight probabilistic paths of multiply scattered protons. Most of these challenges have been or are about to be solved with the help of high-energy and particle physicists, computer science engineers, and applied mathematicians. In this talk, I will give an update on the development of proton CT for applications in proton therapy. This is an update from a talk I gave at the Annual Brazilian Physics Meeting in 2001, when I first suggested that physicists should contribute to the development of modern proton CT. Brazilian physicists have provided many valuable ideas and discussions for this exciting development. (author)

Current and future applications of protons in medical imaging and treatment

International Nuclear Information System (INIS)

Schulte, Reinhard W.

2011-01-01

Protons have a more than 50-year history of applications in medical therapy and more recently also in imaging. Therapy with protons became possible after proton accelerators capable of accelerating protons to energies higher than 150 MeV had been built during the 1940s in a few places around the world. Proton radiography experiments started at the Harvard Cyclotron in the early 1960s. Physicist Allan Cormack, who shared the Nobel Prize for laying the foundation of computed tomography together with Sir Godfrey Hounsfield in 1979, suggested that protons can be used for tomographic imaging for the first time in 1963. Proton CT requires a rotating proton gantry, which did not become available until 1991, at our institution. The interest in proton CT has been renewed due to the fact that exact proton treatment planning is only possible with accurate knowledge of the relative proton stopping power distribution (with respect to water) of the patient, which is best derived by using protons for imaging. Early attempts to do proton CT were hampered by the lack of high-resolution particle trackers, fast data acquisition electronics, and sufficient computing power. Also, efficient proton CT reconstruction algorithms had to be developed that can handle reconstruction based on a large number of proton histories, taking into account the non-straight probabilistic paths of multiply scattered protons. Most of these challenges have been or are about to be solved with the help of high-energy and particle physicists, computer science engineers, and applied mathematicians. In this talk, I will give an update on the development of proton CT for applications in proton therapy. This is an update from a talk I gave at the Annual Brazilian Physics Meeting in 2001, when I first suggested that physicists should contribute to the development of modern proton CT. Brazilian physicists have provided many valuable ideas and discussions for this exciting development. (author)

Plasma-ring, fast-opening switch

International Nuclear Information System (INIS)

Hartman, C.W.; Eddleman, J.; Hammer, J.H.

1986-01-01

The authors discuss a fast-opening switch concept based on magnetically confined plasma rings, PROS (for Plasma Ring Opening Switch). In PROS, the plasma ring, confined by Bθ /sub and B/poloidal /sub fields of a compact torus, provide a low mass, localized conduction path between coaxial electrodes. To operate the switch, driver current is passed across the electrodes through the ring, storing inductive energy in external inductance and between the electrodes on the driver side of the ring. The ring is accelerated away from the driver by the field of the driver current and passes over a load gap transferring the current to the load. The authors distinguish two configurations in PROS, straight PROS where the electrodes are coaxial cylinders, and cone PROS with conical electrodes. In straight PROS ring acceleration takes place during the inductive store period as in foil switches, but with the localized ring providing the current path. Increased performance is predicted for the cone PROS (see figure) which employs compression of the ring in the cone during the inductive store period. Here, the B/θ /sub field of the driver forces the ring towards the apex of the cone but the force is in near balance with the opposing component of the radial equilibrium force of the ring along the cone. As a result, the ring undergoes a slow, quasistatic compression limited only by resistive decay of the ring field. Slow compression allows inductive storage with low-power drivers (homopoloar, magneto cumulative generators, high C-low V capacitor banks, etc.). Near the apex of the cone, near peak compression, the ring is allowed to enter a straight coaxial section where, because of low-mass, it rapidly accelerates to high velocity and crosses the load gap

ISABELLE: a proton-proton colliding beam facility. [Proposal for the construction of ISABELLE

Energy Technology Data Exchange (ETDEWEB)

None

1977-04-01

A proposal is presented for the construction of an Intersecting Storage Accelerator, ISABELLE, to be located at Brookhaven National Laboratory. At this major research facility, colliding beams of protons will be produced and studied by particle physicists. This proposal combines the interests of these particle physicists in exploring a new energy regime with the challenge of building a new research instrument. The proposal results from several years of considering such devices in parallel with extensive developmental work. The proposal is divided into several major parts. Following an introduction is an overall summary of the proposal covering its highlights. Part II contains a thorough discussion of the physics objectives that can be addressed by the storage ring. It begins with an explanation of current theoretical concepts that occupy the curiosity of high energy physicists. Then follows a brief discussion of possible experiments that might be assembled at the interaction regions to test these concepts. The third part of the proposal goes into the details of the design of the intersecting storage accelerators. It begins with a description of the entire facility and the design of the magnet ring structure. The processes of proton beam accumulation and acceleration are thoroughly described. The discussion then turns to the design of the components and subsystems for the accelerator. The accelerator elements are described followed by a description of the physical plant. The cost estimate and time scales are displayed in Part IV. Here the estimate has been based on the experience gained from working with the prototype units at the laboratory. The appendices are an important part of the proposal. The parameter list for the 200 x 200 GeV ISABELLE is carefully documented. An example of a possible research program can be found in an appendix. The performance of prototype units is documented in one of the appendices.

The scrounge-atron: a phased approach to the advanced hydrotest facility utilizing proton radiography

International Nuclear Information System (INIS)

Alford, O.J.; Barnes, P.D. Jr.; Chargin, A.K.; Dekin, W.D.; Hartouni, E.P.; Hockman, J.; Hockman, J.N.; Ladran, A.S.; Libkind, M.A.; Moore, T.L.; Ohnuma, S.; Pastrnak, J.W.; Pico, R.E.; Ruggiero, A.G.; Souza, R.J.; Stoner, J.M.; Wilson, J.H.

1999-01-01

The Department of Energy has initiated its Stockpile Stewardship and Management Program (SSMP) to provide a single, integrated technical program for maintaining the continued safety and reliability of the nation's nuclear weapons stockpile in the absence of nuclear testing. Consistent with the SSMP, the Advanced Hydrotest Facility (AHF) has been conceived to provide improved radiographic imaging with multiple axes and multiple time frames. The AHF would be used to better understand the evolution of nuclear weapon primary implosion shape under normal and accident scenarios. There are three fundamental technologies currently under consideration for use on the AHF. These include linear induction acceleration, inductive-adder pulsed-power technology (both technologies using high current electron beams to produce an intense X-ray beam) and high-energy proton accelerators to produce a proton beam. The Scrounge-atron (a proton synchrotron) was conceived to be a relatively low cost demonstration of the viability of the third technology using bursts of energetic protons, magnetic lenses, and particle detectors to produce the radiographic image. In order for the Scrounge-atron to provide information useful for the AHF technology decision, the accelerator would have to be built as quickly and as economically as possible. These conditions can be met by scrounging parts from decommissioned accelerators across the country, especially the Main Ring at Fermilab. The Scrounge-atron is designed to meet the baseline parameters for single axis proton radiography: a 20 GeV proton beam of ten pulses, 10 11 protons each, spaced 250 ns apart

Effects of magnetic non-linearities on a stored proton beam and their implications for superconducting storage rings

International Nuclear Information System (INIS)

Cornacchia, M.; Evans, L.

1985-06-01

A nonlinear lens may be used to study the effect of high-order multipolar field imperfections on a stored proton beam. Such a nonlinear lens is particulary suitable to simulate field imperfections of the types encountered in coil dominated superconducting magnets. We have studied experimentally at the SPS the effect of high order (5th and 8th) single isolated resonances driven by the nonlinear lens. The width of these resonances is of the order one expects to be caused by field errors in superconducting magnets of the SSC type. The experiment shows that, in absence of tune modulation, these resonances are harmless. Slow crossings of the resonance, on the other hand, have destructive effects on the beam, much more so than fast crossings caused by synchrotron oscillations. In the design of future storage rings, sources of low-frequency tune modulation should be avoided as a way to reduce the harmful effects of high order multipolar field imperfection

Radiation conditions in the ring hall of the IHEP proton synchrotron

International Nuclear Information System (INIS)

Borodin, V.E.; Ermolenko, L.S.; Obryashchikova, L.P.

1975-01-01

The paper presents the results on studying the radiation conditions caused by induced radioactivity of the accelerator units in the ring hall. The data on the induced radioactivity level just on the ring vacuum chamber are reported. Radiation conditions in the most characteristic areas of the hall are considered. The changes in time of the dose rate at the internal target and at the entrance to the hall are shown

Dual ring multilayer ionization chamber and theory-based correction technique for scanning proton therapy.

Science.gov (United States)

Takayanagi, Taisuke; Nihongi, Hideaki; Nishiuchi, Hideaki; Tadokoro, Masahiro; Ito, Yuki; Nakashima, Chihiro; Fujitaka, Shinichiro; Umezawa, Masumi; Matsuda, Koji; Sakae, Takeji; Terunuma, Toshiyuki

2016-07-01

To develop a multilayer ionization chamber (MLIC) and a correction technique that suppresses differences between the MLIC and water phantom measurements in order to achieve fast and accurate depth dose measurements in pencil beam scanning proton therapy. The authors distinguish between a calibration procedure and an additional correction: 1-the calibration for variations in the air gap thickness and the electrometer gains is addressed without involving measurements in water; 2-the correction is addressed to suppress the difference between depth dose profiles in water and in the MLIC materials due to the nuclear interaction cross sections by a semiempirical model tuned by using measurements in water. In the correction technique, raw MLIC data are obtained for each energy layer and integrated after multiplying them by the correction factor because the correction factor depends on incident energy. The MLIC described here has been designed especially for pencil beam scanning proton therapy. This MLIC is called a dual ring multilayer ionization chamber (DRMLIC). The shape of the electrodes allows the DRMLIC to measure both the percentage depth dose (PDD) and integrated depth dose (IDD) because ionization electrons are collected from inner and outer air gaps independently. IDDs for which the beam energies were 71.6, 120.6, 159, 180.6, and 221.4 MeV were measured and compared with water phantom results. Furthermore, the measured PDDs along the central axis of the proton field with a nominal field size of 10 × 10 cm(2) were compared. The spread out Bragg peak was 20 cm for fields with a range of 30.6 and 3 cm for fields with a range of 6.9 cm. The IDDs measured with the DRMLIC using the correction technique were consistent with those that of the water phantom; except for the beam energy of 71.6 MeV, all of the points satisfied the 1% dose/1 mm distance to agreement criterion of the gamma index. The 71.6 MeV depth dose profile showed slight differences in the shallow

Generation of geometrical phases and persistent spin currents in 1-dimensional rings by Lorentz-violating terms

Energy Technology Data Exchange (ETDEWEB)

Casana, R.; Ferreira, M.M., E-mail: manojr.ufma@gmail.com; Mouchrek-Santos, V.E.; Silva, Edilberto O.

2015-06-30

We have demonstrated that Lorentz-violating terms stemming from the fermion sector of the SME are able to generate geometrical phases on the wave function of electrons confined in 1-dimensional rings, as well as persistent spin currents, in the total absence of electromagnetic fields. We have explicitly evaluated the eigenenergies and eigenspinors of the electrons modified by the Lorentz-violating terms, using them to calculate the dynamic and the Aharonov–Anandan phases in the sequel. The total phase presents a pattern very similar to the Aharonov–Casher phase accumulated by electrons in rings under the action of the Rashba interaction. Finally, the persistent spin current were carried out and used to impose upper bounds on the Lorentz-violating parameters.

Accumulator ring lattice for the national spallation neutron source

International Nuclear Information System (INIS)

Gardner, C.J.; Lee, Y.Y.; Luccio, A.U.

1997-01-01

The Accumulator Ring for the proposed National Spallation Neutron Source (NSNS) is to accept a 1.03 millisecond beam pulse from a 1 GeV Proton Linac at a repetition rate of 60 Hz. For each beam pulse, 10 14 protons are to be accumulated via charge-exchange injection. A 295 nanosecond gap in the beam, maintained by an rf system, will allow for extraction to an external target for the production of neutrons by spallation. This paper describes the four-fold symmetric lattice that has been chosen for the ring. The lattice contains four long dispersion-free straight sections to accomodate injection, extraction, rf cavities, and beam scraping respectively. The four-fold symmetry allows for easy adjustment of the tunes and flexibility in the placement of correction elements, and ensures that potentially dangerous betatron structure resonances are avoided

Quantum nano ring composed of quantum dots as a source of pure persistent spin or charge current

International Nuclear Information System (INIS)

Eslami, L.; Faizabadi, E.; Ahmadi, S.

2016-01-01

Spin-dependent persistent current in a quantum ring constituted by two normal and one magnetic quantum dots, in the presence of Rashba spin–orbit interaction is studied by using Green function technique. It is shown that the presence of the magnetic quantum dot breaks the degeneracy of the density of states of electrons with different spin states. Besides, the Rashba spin–orbit interaction along with the magnetic quantum dot develops tunable persistent spin and charge currents. Moreover, the persistent charge current induces a fully adjustable magnetic flux whose direction and magnitude can be tuned by altering the strength of the Rashba spin–orbit interaction. - Highlights: • An array of normal and magnetic quantum dots with Rashba effect is studied. • Spin-dependent persistent current and DOS are studied using Green function method. • The magnetic quantum dot breaks degeneracy of DOS of up and down spin electrons. • The persistent spin and charge currents are tuned by adjusting the Rashba constant. • The persistent charge current induces tunable magnetic field at the center of ring.

Correlations between high momentum particles in proton-proton collisions at high energies

International Nuclear Information System (INIS)

Bobbink, G.J.

1981-01-01

This thesis describes an experiment performed at the CERN Intersecting Storage Rings. The experiment studies the reaction p+p→h 1 +h 2 +X at two centre-of-mass energies, √s=44.7 GeV and √s=62.3 GeV. Two of the outgoing particles (h 1 and h 2 ) are detected in opposite c.m.s. hemispheres at small polar angles with respect to the direction of two incident protons. The remaining particles produced (X) are not detected. The hadrons hsub(i) are identified mesons (π + , π - , K + , K - ) or baryons (p, Λ) with relatively large longitudinal psub(L) and small transverse momentum psub(T). The aim of the experiment is twofold. The first aim is to study whether the momentum distributions of the fast particles hsub(i) are correlated and thereby to constrain the possible interaction mechanisms responsible for the production of high psub(L), low psub(T) particles. The second aim is to establish to what extent the production of pions and kaons in inclusive proton-proton collisions (e.g. p+p→π+X, X=all other particles) resembles the production of pions and kaons in diffractive proton-proton collisions (e.g. p+p→p+π+X, in which the final-state proton has a momentum close to its maximum possible value). (Auth.)

Proton-irradiation technology for high-frequency high-current silicon welding diode manufacturing

Science.gov (United States)

Lagov, P. B.; Drenin, A. S.; Zinoviev, M. A.

2017-05-01

Different proton irradiation regimes were tested to provide more than 20 kHz-frequency, soft reverse recovery “snap-less” behavior, low forward voltage drop and leakage current for 50 mm diameter 7 kA/400 V welding diode Al/Si/Mo structure. Silicon diode with such parameters is very suitable for high frequency resistance welding machines of new generation for robotic welding.

Measurement of pion, kaon and proton production in proton-proton collisions at [Formula: see text] TeV.

Science.gov (United States)

Adam, J; Adamová, D; Aggarwal, M M; Rinella, G Aglieri; Agnello, M; Agrawal, N; Ahammed, Z; Ahmed, I; Ahn, S U; Aimo, I; Aiola, S; Ajaz, M; Akindinov, A; Alam, S N; Aleksandrov, D; Alessandro, B; Alexandre, D; Molina, R Alfaro; Alici, A; Alkin, A; Alme, J; Alt, T; Altinpinar, S; Altsybeev, I; Prado, C Alves Garcia; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arcelli, S; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Augustinus, A; Averbeck, R; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bagnasco, S; Bailhache, R; Bala, R; Baldisseri, A; Ball, M; Pedrosa, F Baltasar Dos Santos; Baral, R C; Barbano, A M; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartalini, P; Bartke, J; Bartsch, E; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Camejo, A Batista; Batyunya, B; Batzing, P C; Bearden, I G; Beck, H; Bedda, C; Behera, N K; Belikov, I; Bellini, F; Martinez, H Bello; Bellwied, R; Belmont, R; Belmont-Moreno, E; Belyaev, V; Bencedi, G; Beole, S; Berceanu, I; Bercuci, A; Berdnikov, Y; Berenyi, D; Bertens, R A; Berzano, D; Betev, L; Bhasin, A; Bhat, I R; Bhati, A K; Bhattacharjee, B; Bhom, J; Bianchi, L; Bianchi, N; Bianchin, C; Bielčík, J; Bielčíková, J; Bilandzic, A; Biswas, S; Bjelogrlic, S; Blanco, F; Blau, D; Blume, C; Bock, F; Bogdanov, A; Bøggild, H; Boldizsár, L; Bombara, M; Book, J; Borel, H; Borissov, A; Borri, M; Bossú, F; Botje, M; Botta, E; Böttger, S; Braun-Munzinger, P; Bregant, M; Breitner, T; Broker, T A; Browning, T A; Broz, M; Brucken, E J; Bruna, E; Bruno, G E; Budnikov, D; Buesching, H; Bufalino, S; Buncic, P; Busch, O; Buthelezi, Z; Buxton, J T; Caffarri, D; Cai, X; Caines, H; Diaz, L Calero; Caliva, A; Villar, E Calvo; Camerini, P; Carena, F; Carena, W; Castellanos, J Castillo; Castro, A J; Casula, E A R; Cavicchioli, C; Sanchez, C Ceballos; Cepila, J; Cerello, P; Chang, B; Chapeland, S; Chartier, M; Charvet, J L; Chattopadhyay, S; Chattopadhyay, S; Chelnokov, V; Cherney, M; Cheshkov, C; Cheynis, B; Barroso, V Chibante; Chinellato, D D; Chochula, P; Choi, K; Chojnacki, M; Choudhury, S; Christakoglou, P; Christensen, C H; Christiansen, P; Chujo, T; Chung, S U; Cicalo, C; Cifarelli, L; Cindolo, F; Cleymans, J; Colamaria, F; Colella, D; Collu, A; Colocci, M; Balbastre, G Conesa; Valle, Z Conesa Del; Connors, M E; Contreras, J G; Cormier, T M; Morales, Y Corrales; Maldonado, I Cortés; Cortese, P; Cosentino, M R; Costa, F; Crochet, P; Albino, R Cruz; Cuautle, E; Cunqueiro, L; Dahms, T; Dainese, A; Danu, A; Das, D; Das, I; Das, S; Dash, A; Dash, S; De, S; Caro, A De; Cataldo, G de; Cuveland, J de; Falco, A De; Gruttola, D De; Marco, N De; Pasquale, S De; Deisting, A; Deloff, A; Dénes, E; D'Erasmo, G; Bari, D Di; Mauro, A Di; Nezza, P Di; Corchero, M A Diaz; Dietel, T; Dillenseger, P; Divià, R; Djuvsland, Ø; Dobrin, A; Dobrowolski, T; Gimenez, D Domenicis; Dönigus, B; Dordic, O; Dubey, A K; Dubla, A; Ducroux, L; Dupieux, P; Ehlers, R J; Elia, D; Engel, H; Erazmus, B; Erhardt, F; Eschweiler, D; Espagnon, B; Estienne, M; Esumi, S; Eum, J; Evans, D; Evdokimov, S; Eyyubova, G; Fabbietti, L; Fabris, D; Faivre, J; Fantoni, A; Fasel, M; Feldkamp, L; Felea, D; Feliciello, A; Feofilov, G; Ferencei, J; Téllez, A Fernández; Ferreiro, E G; Ferretti, A; Festanti, A; Figiel, J; Figueredo, M A S; Filchagin, S; Finogeev, D; Fionda, F M; Fiore, E M; Fleck, M G; Floris, M; Foertsch, S; Foka, P; Fokin, S; Fragiacomo, E; Francescon, A; Frankenfeld, U; Fuchs, U; Furget, C; Furs, A; Girard, M Fusco; Gaardhøje, J J; Gagliardi, M; Gago, A M; Gallio, M; Gangadharan, D R; Ganoti, P; Gao, C; Garabatos, C; Garcia-Solis, E; Gargiulo, C; Gasik, P; Germain, M; Gheata, A; Gheata, M; Ghosh, P; Ghosh, S K; Gianotti, P; Giubellino, P; Giubilato, P; Dziadus, E Gladysz; Glässel, P; Ramirez, A Gomez; Zamora, P González; Gorbunov, S; Görlich, L; Gotovac, S; Grabski, V; Graczykowski, L K; Grelli, A; Grigoras, A; Grigoras, C; Grigoriev, V; Grigoryan, A; Grigoryan, S; Grinyov, B; Grion, N; Grosse-Oetringhaus, J F; Grossiord, J-Y; Grosso, R; Guber, F; Guernane, R; Guerzoni, B; Gulbrandsen, K; Gulkanyan, H; Gunji, T; Gupta, A; Gupta, R; Haake, R; Haaland, Ø; Hadjidakis, C; Haiduc, M; Hamagaki, H; Hamar, G; Hanratty, L D; Hansen, A; Harris, J W; Hartmann, H; Harton, A; Hatzifotiadou, D; Hayashi, S; Heckel, S T; Heide, M; Helstrup, H; Herghelegiu, A; Corral, G Herrera; Hess, B A; Hetland, K F; Hilden, T E; Hillemanns, H; Hippolyte, B; Hristov, P; Huang, M; Humanic, T J; Hussain, N; Hussain, T; Hutter, D; Hwang, D S; Ilkaev, R; Ilkiv, I; Inaba, M; Ionita, C; Ippolitov, M; Irfan, M; Ivanov, M; Ivanov, V; Izucheev, V; Jacobs, P M; Jahnke, C; Jang, H J; Janik, M A; Jayarathna, P H S Y; Jena, C; Jena, S; Bustamante, R T Jimenez; Jones, P G; Jung, H; Jusko, A; Kalinak, P; Kalweit, A; Kamin, J; Kang, J H; Kaplin, V; Kar, S; Uysal, A Karasu; Karavichev, O; Karavicheva, T; Karpechev, E; Kebschull, U; Keidel, R; Keijdener, D L D; Keil, M; Khan, K H; Khan, M M; Khan, P; Khan, S A; Khanzadeev, A; Kharlov, Y; Kileng, B; Kim, B; Kim, D W; Kim, D J; Kim, H; Kim, J S; Kim, M; Kim, M; Kim, S; Kim, T; Kirsch, S; Kisel, I; Kiselev, S; Kisiel, A; Kiss, G; Klay, J L; Klein, C; Klein, J; Klein-Bösing, C; Kluge, A; Knichel, M L; Knospe, A G; Kobayashi, T; Kobdaj, C; Kofarago, M; Köhler, M K; Kollegger, T; Kolojvari, A; Kondratiev, V; Kondratyeva, N; Kondratyuk, E; Konevskikh, A; Kouzinopoulos, C; Kovalenko, O; Kovalenko, V; Kowalski, M; Kox, S; Meethaleveedu, G Koyithatta; Kral, J; Králik, I; Kravčáková, A; Krelina, M; Kretz, M; Krivda, M; Krizek, F; Kryshen, E; Krzewicki, M; Kubera, A M; Kučera, V; Kucheriaev, Y; Kugathasan, T; Kuhn, C; Kuijer, P G; Kulakov, I; Kumar, J; Kumar, L; Kurashvili, P; Kurepin, A; Kurepin, A B; Kuryakin, A; Kushpil, S; Kweon, M J; Kwon, Y; Pointe, S L La; Rocca, P La; Fernandes, C Lagana; Lakomov, I; Langoy, R; Lara, C; Lardeux, A; Lattuca, A; Laudi, E; Lea, R; Leardini, L; Lee, G R; Lee, S; Legrand, I; Lehnert, J; Lemmon, R C; Lenti, V; Leogrande, E; Monzón, I León; Leoncino, M; Lévai, P; Li, S; Li, X; Lien, J; Lietava, R; Lindal, S; Lindenstruth, V; Lippmann, C; Lisa, M A; Ljunggren, H M; Lodato, D F; Loenne, P I; Loggins, V R; Loginov, V; Loizides, C; Lopez, X; Torres, E López; Lowe, A; Lu, X-G; Luettig, P; Lunardon, M; Luparello, G; Maevskaya, A; Mager, M; Mahajan, S; Mahmood, S M; Maire, A; Majka, R D; Malaev, M; Cervantes, I Maldonado; Malinina, L; Mal'Kevich, D; Malzacher, P; Mamonov, A; Manceau, L; Manko, V; Manso, F; Manzari, V; Marchisone, M; Mareš, J; Margagliotti, G V; Margotti, A; Margutti, J; Marín, A; Markert, C; Marquard, M; Martin, N A; Blanco, J Martin; Martinengo, P; Martínez, M I; Martínez García, G; Pedreira, M Martinez; Martynov, Y; Mas, A; Masciocchi, S; Masera, M; Masoni, A; Massacrier, L; Mastroserio, A; Masui, H; Matyja, A; Mayer, C; Mazer, J; Mazzoni, M A; Mcdonald, D; Meddi, F; Menchaca-Rocha, A; Meninno, E; Pérez, J Mercado; Meres, M; Miake, Y; Mieskolainen, M M; Mikhaylov, K; Milano, L; Milosevic, J; Minervini, L M; Mischke, A; Mishra, A N; Miśkowiec, D; Mitra, J; Mitu, C M; Mohammadi, N; Mohanty, B; Molnar, L; Zetina, L Montaño; Montes, E; Morando, M; Godoy, D A Moreira De; Moretto, S; Morreale, A; Morsch, A; Muccifora, V; Mudnic, E; Mühlheim, D; Muhuri, S; Mukherjee, M; Müller, H; Mulligan, J D; Munhoz, M G; Murray, S; Musa, L; Musinsky, J; Nandi, B K; Nania, R; Nappi, E; Naru, M U; Nattrass, C; Nayak, K; Nayak, T K; Nazarenko, S; Nedosekin, A; Nellen, L; Ng, F; Nicassio, M; Niculescu, M; Niedziela, J; Nielsen, B S; Nikolaev, S; Nikulin, S; Nikulin, V; Noferini, F; Nomokonov, P; Nooren, G; Norman, J; Nyanin, A; Nystrand, J; Oeschler, H; Oh, S; Oh, S K; Ohlson, A; Okatan, A; Okubo, T; Olah, L; Oleniacz, J; Silva, A C Oliveira Da; Oliver, M H; Onderwaater, J; Oppedisano, C; Velasquez, A Ortiz; Oskarsson, A; Otwinowski, J; Oyama, K; Ozdemir, M; Pachmayer, Y; Pagano, P; Paić, G; Pajares, C; Pal, S K; Pan, J; Pandey, A K; Pant, D; Papikyan, V; Pappalardo, G S; Pareek, P; Park, W J; Parmar, S; Passfeld, A; Paticchio, V; Paul, B; Pawlak, T; Peitzmann, T; Costa, H Pereira Da; Filho, E Pereira De Oliveira; Peresunko, D; Lara, C E Pérez; Peskov, V; Pestov, Y; Petráček, V; Petrov, V; Petrovici, M; Petta, C; Piano, S; Pikna, M; Pillot, P; Pinazza, O; Pinsky, L; Piyarathna, D B; Płoskoń, M; Planinic, M; Pluta, J; Pochybova, S; Podesta-Lerma, P L M; Poghosyan, M G; Polichtchouk, B; Poljak, N; Poonsawat, W; Pop, A; Porteboeuf-Houssais, S; Porter, J; Pospisil, J; Prasad, S K; Preghenella, R; Prino, F; Pruneau, C A; Pshenichnov, I; Puccio, M; Puddu, G; Pujahari, P; Punin, V; Putschke, J; Qvigstad, H; Rachevski, A; Raha, S; Rajput, S; Rak, J; Rakotozafindrabe, A; Ramello, L; Raniwala, R; Raniwala, S; Räsänen, S S; Rascanu, B T; Rathee, D; Razazi, V; Read, K F; Real, J S; Redlich, K; Reed, R J; Rehman, A; Reichelt, P; Reicher, M; Reidt, F; Ren, X; Renfordt, R; Reolon, A R; Reshetin, A; Rettig, F; Revol, J-P; Reygers, K; Riabov, V; Ricci, R A; Richert, T; Richter, M; Riedler, P; Riegler, W; Riggi, F; Ristea, C; Rivetti, A; Rocco, E; Cahuantzi, M Rodríguez; Manso, A Rodriguez; Røed, K; Rogochaya, E; Rohr, D; Röhrich, D; Romita, R; Ronchetti, F; Ronflette, L; Rosnet, P; Rossi, A; Roukoutakis, F; Roy, A; Roy, C; Roy, P; Montero, A J Rubio; Rui, R; Russo, R; Ryabinkin, E; Ryabov, Y; Rybicki, A; Sadovsky, S; Šafařík, K; Sahlmuller, B; Sahoo, P; Sahoo, R; Sahoo, S; Sahu, P K; Saini, J; Sakai, S; Saleh, M A; Salgado, C A; Salzwedel, J; Sambyal, S; Samsonov, V; Castro, X Sanchez; Šándor, L; Sandoval, A; Sano, M; Santagati, G; Sarkar, D; Scapparone, E; Scarlassara, F; Scharenberg, R P; Schiaua, C; Schicker, R; Schmidt, C; Schmidt, H R; Schuchmann, S; Schukraft, J; Schulc, M; Schuster, T; Schutz, Y; Schwarz, K; Schweda, K; Scioli, G; Scomparin, E; Scott, R; Seeder, K S; Seger, J E; Sekiguchi, Y; Selyuzhenkov, I; Senosi, K; Seo, J; Serradilla, E; Sevcenco, A; Shabanov, A; Shabetai, A; Shadura, O; Shahoyan, R; Shangaraev, A; Sharma, A; Sharma, N; Shigaki, K; Shtejer, K; Sibiriak, Y; Siddhanta, S; Sielewicz, K M; Siemiarczuk, T; Silvermyr, D; Silvestre, C; Simatovic, G; Simonetti, G; Singaraju, R; Singh, R; Singha, S; Singhal, V; Sinha, B C; Sinha, T; Sitar, B; Sitta, M; Skaali, T B; Slupecki, M; Smirnov, N; Snellings, R J M; Snellman, T W; Søgaard, C; Soltz, R; Song, J; Song, M; Song, Z; Soramel, F; Sorensen, S; Spacek, M; Spiriti, E; Sputowska, I; Stassinaki, M Spyropoulou; Srivastava, B K; Stachel, J; Stan, I; Stefanek, G; Steinpreis, M; Stenlund, E; Steyn, G; Stiller, J H; Stocco, D; Strmen, P; Suaide, A A P; Sugitate, T; Suire, C; Suleymanov, M; Sultanov, R; Šumbera, M; Symons, T J M; Szabo, A; Toledo, A Szanto de; Szarka, I; Szczepankiewicz, A; Szymanski, M; Takahashi, J; Tanaka, N; Tangaro, M A; Takaki, J D Tapia; Peloni, A Tarantola; Tariq, M; Tarzila, M G; Tauro, A; Muñoz, G Tejeda; Telesca, A; Terasaki, K; Terrevoli, C; Teyssier, B; Thäder, J; Thomas, D; Tieulent, R; Timmins, A R; Toia, A; Trogolo, S; Trubnikov, V; Trzaska, W H; Tsuji, T; Tumkin, A; Turrisi, R; Tveter, T S; Ullaland, K; Uras, A; Usai, G L; Utrobicic, A; Vajzer, M; Vala, M; Palomo, L Valencia; Vallero, S; Maarel, J Van Der; Hoorne, J W Van; Leeuwen, M van; Vanat, T; Vyvre, P Vande; Varga, D; Vargas, A; Vargyas, M; Varma, R; Vasileiou, M; Vasiliev, A; Vauthier, A; Vechernin, V; Veen, A M; Veldhoen, M; Velure, A; Venaruzzo, M; Vercellin, E; Limón, S Vergara; Vernet, R; Verweij, M; Vickovic, L; Viesti, G; Viinikainen, J; Vilakazi, Z; Baillie, O Villalobos; Vinogradov, A; Vinogradov, L; Vinogradov, Y; Virgili, T; Vislavicius, V; Viyogi, Y P; Vodopyanov, A; Völkl, M A; Voloshin, K; Voloshin, S A; Volpe, G; Haller, B von; Vorobyev, I; Vranic, D; Vrláková, J; Vulpescu, B; Vyushin, A; Wagner, B; Wagner, J; Wang, H; Wang, M; Wang, Y; Watanabe, D; Weber, M; Weber, S G; Wessels, J P; Westerhoff, U; Wiechula, J; Wikne, J; Wilde, M; Wilk, G; Wilkinson, J; Williams, M C S; Windelband, B; Winn, M; Yaldo, C G; Yamaguchi, Y; Yang, H; Yang, P; Yano, S; Yasnopolskiy, S; Yin, Z; Yokoyama, H; Yoo, I-K; Yurchenko, V; Yushmanov, I; Zaborowska, A; Zaccolo, V; Zaman, A; Zampolli, C; Zanoli, H J C; Zaporozhets, S; Zarochentsev, A; Závada, P; Zaviyalov, N; Zbroszczyk, H; Zgura, I S; Zhalov, M; Zhang, H; Zhang, X; Zhang, Y; Zhao, C; Zhigareva, N; Zhou, D; Zhou, Y; Zhou, Z; Zhu, H; Zhu, J; Zhu, X; Zichichi, A; Zimmermann, A; Zimmermann, M B; Zinovjev, G; Zyzak, M

The measurement of primary [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] production at mid-rapidity ([Formula: see text] 0.5) in proton-proton collisions at [Formula: see text][Formula: see text] 7 TeV performed with a large ion collider experiment at the large hadron collider (LHC) is reported. Particle identification is performed using the specific ionisation energy-loss and time-of-flight information, the ring-imaging Cherenkov technique and the kink-topology identification of weak decays of charged kaons. Transverse momentum spectra are measured from 0.1 up to 3 GeV/[Formula: see text] for pions, from 0.2 up to 6 GeV/[Formula: see text] for kaons and from 0.3 up to 6 GeV/[Formula: see text] for protons. The measured spectra and particle ratios are compared with quantum chromodynamics-inspired models, tuned to reproduce also the earlier measurements performed at the LHC. Furthermore, the integrated particle yields and ratios as well as the average transverse momenta are compared with results at lower collision energies.

E-P instability in the NSNS accumulator ring

Energy Technology Data Exchange (ETDEWEB)

Ruggiero, A.G.; Blaskiewicz, M.

1997-08-01

It has been speculated that the intensity limitation observed in the Los Alamos Proton Storage Ring (PSR) is caused by a coherent instability induced by the presence of pockets of electrons generated by scattering with the molecules of the vacuum residual gas. A theoretical explanation of the e-p instability of course does exist, and is similar to the one developed for the ion-induced instability in electron storage rings. Considering the large beam power (3 MW) involved in the NSNS Accumulator Ring, and the consequences caused by even a small amount of beam loss, we need to carefully assess the effects of electrons that may be generated in the vacuum chamber.

State of development of CERN proton storage rings

CERN Document Server

Huber, H

1973-01-01

The storage rings are briefly described and the 'luminosity', meaning a standardised counting method, is stated for the energies available at the centre of gravity. The maximum of luminosity reached so far is compared with the maximum possible luminosity and the reasons for the discrepancy are discussed. An example shows graphs of luminosity and of the beams after completion of the storage process, as functions of time. (2 refs).

The merging of the Intersecting Storage Rings for a 60 GeV collider with the 400 GeV proton synchrotron

International Nuclear Information System (INIS)

1978-01-01

Following the recommendation of the Workshop on Future ISR Physics, 1976, a study has been made of using the existing ISR (Intersecting Storage Rings) equipment at CERN to build a single 60 GeV storage ring (Merged ISR) for beam collision with the 400 GeV Super Proton Synchrotron (SPS). At a minimum cost of 103 MSF, a single-intersection physics facility with a 3.55 0 crossing angle, a luminosity of 1.2 10 30 cm -2 s -1 and a centre-of-mass energy of 255 GeV could be built. For a further 7 MSF, the luminosity could be easily raised to 3.8 10 30 cm -2 s -1 . Alternatively, the MISR can be built to give a single, zero-angle crossing with a luminosity of 1.1 10 32 cm -2 s -1 . The last solution is not recommended, however, as the free space around the intersection is extremely limited and the facility becomes very specialized in the type of physics experiments which could be performed. In all cases, the project could be completed in three years and two months with a 9 1/2-month shutdown for the SPS and 18 months between the closing down of the ISR and the start-up of MISR. (Auth.)

ELECTRON CLOUD EFFECTS IN HIGH INTENSITY PROTON ACCELERATORS.

Energy Technology Data Exchange (ETDEWEB)

WEI,J.; MACEK,R.J.

2002-04-14

One of the primary concerns in the design and operation of high-intensity proton synchrotrons and accumulators is the electron cloud and associated beam loss and instabilities. Electron-cloud effects are observed at high-intensity proton machines like the Los Alamos National Laboratory's PSR and CERN's SPS, and investigated experimentally and theoretically. In the design of next-generation high-intensity proton accelerators like the Spallation Neutron Source ring, emphasis is made in minimizing electron production and in enhancing Landau damping. This paper reviews the present understanding of the electron-cloud effects and presents mitigation measures.

Quantum Mechanics/Molecular Mechanics Simulations Identify the Ring-Opening Mechanism of Creatininase.

Science.gov (United States)

Jitonnom, Jitrayut; Mujika, Jon I; van der Kamp, Marc W; Mulholland, Adrian J

2017-12-05

Creatininase catalyzes the conversion of creatinine (a biosensor for kidney function) to creatine via a two-step mechanism: water addition followed by ring opening. Water addition is common to other known cyclic amidohydrolases, but the precise mechanism for ring opening is still under debate. The proton donor in this step is either His178 or a water molecule bound to one of the metal ions, and the roles of His178 and Glu122 are unclear. Here, the two possible reaction pathways have been fully examined by means of combined quantum mechanics/molecular mechanics simulations at the SCC-DFTB/CHARMM22 level of theory. The results indicate that His178 is the main catalytic residue for the whole reaction and explain its role as proton shuttle during the ring-opening step. In the first step, His178 provides electrostatic stabilization to the gem-diolate tetrahedral intermediate. In the second step, His178 abstracts the hydroxyl proton of the intermediate and delivers it to the cyclic amide nitrogen, leading to ring opening. The latter is the rate-limiting step with a free energy barrier of 18.5 kcal/mol, in agreement with the experiment. We find that Glu122 must be protonated during the enzyme reaction, so that it can form a stable hydrogen bond with its neighboring water molecule. Simulations of the E122Q mutant showed that this replacement disrupts the H-bond network formed by three conserved residues (Glu34, Ser78, and Glu122) and water, increasing the energy barrier. Our computational studies provide a comprehensive explanation for previous structural and kinetic observations, including why the H178A mutation causes a complete loss of activity but the E122Q mutation does not.

Discovery of energetic molecular ions (NO+ and O2+) in the storm time ring current

International Nuclear Information System (INIS)

Klecker, B.; Moebius, E.; Hovestadt, D.; Scholer, M.; Gloeckler, G.; Ipavich, F.M.

1986-01-01

A few hours after the onset of a large geomagnetic storm on September 4, 1984, energetic molecular ions in the mass range 28--32, predminantly NO + and O 2 + , have been discovered in the outer ring current at L--7. The data have been obtained with the time-of-flight spectrometer SULEICA on the AMPTE/IRM spacecraft. We find at 160 keV/e a mean abundance ratio of the molecular ions relative to O + ions of 0.031 +- 0.004. During quiet times no molecular ions are observed, the 1 sigma upper limit of the ratio derived by averaging over several quiet periods is 0.003. The observations demonstrate the injection of ionospheric plasma into the storm time ring current and the subsequent acceleration to energies of several hundred keV on a time scale of a few hours after the onset of the magnetic storm

Proton-irradiation technology for high-frequency high-current silicon welding diode manufacturing

International Nuclear Information System (INIS)

Lagov, P B; Drenin, A S; Zinoviev, M A

2017-01-01

Different proton irradiation regimes were tested to provide more than 20 kHz-frequency, soft reverse recovery “snap-less” behavior, low forward voltage drop and leakage current for 50 mm diameter 7 kA/400 V welding diode Al/Si/Mo structure. Silicon diode with such parameters is very suitable for high frequency resistance welding machines of new generation for robotic welding. (paper)

The PEP electron-positron ring

International Nuclear Information System (INIS)

Rees, J.R.

1988-01-01

The first stage of the positron-electron-proton (PEP) colliding-beam system which has been under joint study by a Lawrence Berkeley Laboratory-Stanford Linear Accelerator Center team for the past two years, will be the electron-positron storage ring. The physics justification for the e + e/sup minus/ ring is summarized briefly and the proposed facility is described. The ring will have six arcs having gross radii of about 220 m and six interaction regions located at the centers of straight sections about 130 m long. The longitudinal distance left free for experimental apparatus at the intersection regions will be 20 m. The range of operating beam energies will be from 5 GeV to 15 GeV. The design luminosity at 15 GeV will be 10 32 cm/sup minus 2/s/sup minus 1/, and the luminosity will vary approximately as the square of the beam energy. Alternative methods under consideration for adjusting the beam cross-section are discussed. The designs of the storage ring subsystems and of the conventional facilities including the experimental halls at the interaction regions are described

Fermilab Antiproton source, Recycler ring and Main Injector

Energy Technology Data Exchange (ETDEWEB)

Nagaitsev, Sergei [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2013-03-22

The antiproton source for a proton-antiproton collider at Fermilab was proposed in 1976 [1]. The proposal argued that the requisite luminosity (~10²⁹ cm^-2sec^-1) could be achieved with a facility that would produce and cool approximately 10¹¹ antiprotons per day. Funding for the Tevatron I project (to construct the Antiproton source) was initiated in 1981 and the Tevatron ring itself was completed, as a fixed target accelerator, in the summer of 1983 and the Antiproton Source was completed in 1985. At the end of its operations in 2011, the Fermilab antiproton production complex consisted of a sophisticated target system, three 8-GeV storage rings (namely the Debuncher, Accumulator and Recycler), 25 independent multi-GHz stochastic cooling systems, the world’s only relativistic electron cooling system and a team of technical experts equal to none. Sustained accumulation of antiprotons was possible at the rate of greater than 2.5×10¹¹ per hour. Record-size stacks of antiprotons in excess of 3×10¹² were accumulated in the Accumulator ring and 6×10¹² in the Recycler. In some special cases, the antiprotons were stored in rings for more than 50 days. Note, that over the years, some 10¹⁶ antiprotons were produced and accumulated at Fermilab, which is about 17 nanograms and more than 90% of the world’s total man-made quantity of nuclear antimatter. The accelerator complex at Fermilab supported a broad physics program including the Tevatron Collider Run II [2], neutrino experiments using 8 GeV and 120 GeV proton beams, as well as a test beam facility and other fixed target experiments using 120 GeV primary proton beams. The following sections provide a brief description of Fermilab accelerators as they operated at the end of the Collider Run II (2011).

Dual ring multilayer ionization chamber and theory-based correction technique for scanning proton therapy

International Nuclear Information System (INIS)

Takayanagi, Taisuke; Nishiuchi, Hideaki; Fujitaka, Shinichiro; Umezawa, Masumi; Nihongi, Hideaki; Tadokoro, Masahiro; Ito, Yuki; Nakashima, Chihiro; Matsuda, Koji; Sakae, Takeji; Terunuma, Toshiyuki

2016-01-01

Purpose: To develop a multilayer ionization chamber (MLIC) and a correction technique that suppresses differences between the MLIC and water phantom measurements in order to achieve fast and accurate depth dose measurements in pencil beam scanning proton therapy. Methods: The authors distinguish between a calibration procedure and an additional correction: 1—the calibration for variations in the air gap thickness and the electrometer gains is addressed without involving measurements in water; 2—the correction is addressed to suppress the difference between depth dose profiles in water and in the MLIC materials due to the nuclear interaction cross sections by a semiempirical model tuned by using measurements in water. In the correction technique, raw MLIC data are obtained for each energy layer and integrated after multiplying them by the correction factor because the correction factor depends on incident energy. The MLIC described here has been designed especially for pencil beam scanning proton therapy. This MLIC is called a dual ring multilayer ionization chamber (DRMLIC). The shape of the electrodes allows the DRMLIC to measure both the percentage depth dose (PDD) and integrated depth dose (IDD) because ionization electrons are collected from inner and outer air gaps independently. Results: IDDs for which the beam energies were 71.6, 120.6, 159, 180.6, and 221.4 MeV were measured and compared with water phantom results. Furthermore, the measured PDDs along the central axis of the proton field with a nominal field size of 10 × 10 cm 2 were compared. The spread out Bragg peak was 20 cm for fields with a range of 30.6 and 3 cm for fields with a range of 6.9 cm. The IDDs measured with the DRMLIC using the correction technique were consistent with those that of the water phantom; except for the beam energy of 71.6 MeV, all of the points satisfied the 1% dose/1 mm distance to agreement criterion of the gamma index. The 71.6 MeV depth dose profile showed slight

Electric current modulation by gate frequency in a quantum ring nanotransistor

International Nuclear Information System (INIS)

Konopka, M.; Bokes, P.

2013-01-01

We presented a computational study of a dynamical gate effect applied to a tight-binding model of a ring-shaped quantum-interference nanotransistor. Compared to our former analysis, we used a model of the gate that not only controls on-site energies of the atoms but can also transfer electrons to or from the device. We have found that the electric current is modulated by the gate frequency also in this more general model. The simulations have been performed using our home-developed generalised stroboscopic wave packet approach which is very suitable for open systems and time-dependent effects. (authors)

Proton and non-proton activation of ASIC channels.

Directory of Open Access Journals (Sweden)

Ivan Gautschi

Full Text Available The Acid-Sensing Ion Channels (ASIC exhibit a fast desensitizing current when activated by pH values below 7.0. By contrast, non-proton ligands are able to trigger sustained ASIC currents at physiological pHs. To analyze the functional basis of the ASIC desensitizing and sustained currents, we have used ASIC1a and ASIC2a mutants with a cysteine in the pore vestibule for covalent binding of different sulfhydryl reagents. We found that ASIC1a and ASIC2a exhibit two distinct currents, a proton-induced desensitizing current and a sustained current triggered by sulfhydryl reagents. These currents differ in their pH dependency, their sensitivity to the sulfhydryl reagents, their ionic selectivity and their relative magnitude. We propose a model for ASIC1 and ASIC2 activity where the channels can function in two distinct modes, a desensitizing mode and a sustained mode depending on the activating ligands. The pore vestibule of the channel represents a functional site for binding non-proton ligands to activate ASIC1 and ASIC2 at neutral pH and to prevent channel desensitization.

Proton and non-proton activation of ASIC channels.

Science.gov (United States)

Gautschi, Ivan; van Bemmelen, Miguel Xavier; Schild, Laurent

2017-01-01

The Acid-Sensing Ion Channels (ASIC) exhibit a fast desensitizing current when activated by pH values below 7.0. By contrast, non-proton ligands are able to trigger sustained ASIC currents at physiological pHs. To analyze the functional basis of the ASIC desensitizing and sustained currents, we have used ASIC1a and ASIC2a mutants with a cysteine in the pore vestibule for covalent binding of different sulfhydryl reagents. We found that ASIC1a and ASIC2a exhibit two distinct currents, a proton-induced desensitizing current and a sustained current triggered by sulfhydryl reagents. These currents differ in their pH dependency, their sensitivity to the sulfhydryl reagents, their ionic selectivity and their relative magnitude. We propose a model for ASIC1 and ASIC2 activity where the channels can function in two distinct modes, a desensitizing mode and a sustained mode depending on the activating ligands. The pore vestibule of the channel represents a functional site for binding non-proton ligands to activate ASIC1 and ASIC2 at neutral pH and to prevent channel desensitization.

High luminosity polarized proton collisions at RHIC

International Nuclear Information System (INIS)

Roser, T.

2001-01-01

The Brookhaven Relativistic Heavy Ion Collider (RHIC) provides the unique opportunity to collide polarized proton beams at a center-of-mass energy of up to 500 GeV and luminosities of up to 2 x 10 32 cm -2 s -1 . Such high luminosity and high energy polarized proton collisions will open up the possibility of studying spin effects in hard processes. However, the acceleration of polarized beams in circular accelerators is complicated by the numerous depolarizing spin resonances. Using a partial Siberian snake and a rf dipole that ensure stable adiabatic spin motion during acceleration has made it possible to accelerate polarized protons to 25 GeV at the Brookhaven AGS. After successful operation of RHIC with gold beams polarized protons from the AGS have been successfully injected into RHIC and accelerated using a full Siberian snakes built from four superconducting helical dipoles. A new high energy proton polarimeter was also successfully commissioned. Operation with two snakes per RHIC ring is planned for next year

ASTOR, concept of a combined acceleration and storage ring for the production of intense pulsed or continuous beams of neutrinos, pions, muons, kaons and neutrons

International Nuclear Information System (INIS)

Joho, W.

1983-01-01

A new concept for a high intensity accelerator for 2 GeV protons using the continuous 590 MeV beam from the present ring cyclotron has been worked out at SIN. To suppress the cosmic background in neutrino experiments a pulsed beam with high peak current and low duty cycle is required. Using the so called phase expansion effect 1,2 one can combine the acceleration and storage effect in a single isochronous cyclotron ASTOR. With the help of several RF cavities, positioned at different radii, it is possible to operate ASTOR either in a pulsed mode at 1500 Hz or in a continuous mode. The anticipated beam powers are .8 MW and 4 MW respectively. The ASTOR concept is also applicable in a possible kaon factory design, acting as an interface between the SIN ring cyclotron and a 50 Hz synchrotron for 15 to 20 GeV protons

Role of pendant proton relays and proton-coupled electron transfer on the hydrogen evolution reaction by nickel hangman porphyrins

Science.gov (United States)

Bediako, D. Kwabena; Solis, Brian H.; Dogutan, Dilek K.; Roubelakis, Manolis M.; Maher, Andrew G.; Lee, Chang Hoon; Chambers, Matthew B.; Hammes-Schiffer, Sharon; Nocera, Daniel G.

2014-01-01

The hangman motif provides mechanistic insights into the role of pendant proton relays in governing proton-coupled electron transfer (PCET) involved in the hydrogen evolution reaction (HER). We now show improved HER activity of Ni compared with Co hangman porphyrins. Cyclic voltammogram data and simulations, together with computational studies using density functional theory, implicate a shift in electrokinetic zone between Co and Ni hangman porphyrins due to a change in the PCET mechanism. Unlike the Co hangman porphyrin, the Ni hangman porphyrin does not require reduction to the formally metal(0) species before protonation by weak acids in acetonitrile. We conclude that protonation likely occurs at the Ni(I) state followed by reduction, in a stepwise proton transfer–electron transfer pathway. Spectroelectrochemical and computational studies reveal that upon reduction of the Ni(II) compound, the first electron is transferred to a metal-based orbital, whereas the second electron is transferred to a molecular orbital on the porphyrin ring. PMID:25298534

Manifestations of geometric phases in a proton electric-dipole-moment experiment in an all-electric storage ring

Science.gov (United States)

Silenko, Alexander J.

2017-12-01

We consider a proton electric-dipole-moment experiment in an all-electric storage ring when the spin is frozen and local longitudinal and vertical electric fields alternate. In this experiment, the geometric (Berry) phases are very important. Due to the these phases, the spin rotates about the radial axis. The corresponding systematic error is rather important while it can be canceled with clockwise and counterclockwise beams. The geometric phases also lead to the spin rotation about the radial axis. This effect can be canceled with clockwise and counterclockwise beams as well. The sign of the azimuthal component of the angular velocity of the spin precession depends on the starting point where the spin orientation is perfect. The radial component of this quantity keeps its value and sign for each starting point. When the longitudinal and vertical electric fields are joined in the same sections without any alternation, the systematic error due to the geometric phases does not appear but another systematic effect of the spin rotation about the azimuthal axis takes place. It has opposite signs for clockwise and counterclockwise beams.

Some aspects of radiation protection near high-energy proton accelerators

CERN Document Server

Tuyn, Jan Willem Nicolaas

1977-01-01

The CERN site near Geneva borders Satigny and Meyrin in Switzerland and Saint-Genis-Pouilly and Prevention in France. The 600 MeV proton synchrocyclotron (SC) has been in operation since 1957, the 28 GeV proton synchrotron (PS) since 1960, and the Intersecting Storage Rings (ISR) since 1971. A fourth large accelerator, the 400 GeV super proton synchrotron (SPS), will soon be in service. The internal and external radiation protection problems caused by these machines, together with the solutions, are reviewed in the light of experience. (5 refs).

Development of RF-linac and storage ring system for high-current experiments at GSI

International Nuclear Information System (INIS)

Hofmann, I.

1986-08-01

The heavy ion facility under construction at GSI is suitable for the generation of high-current beams. It consists of a new high-current injector into the Unilac and a synchrotron and storage ring. We discuss the capability of this system to produce short pulses of heavy ions with a specific energy of the order of 0.1 MJ/g. Under these conditions the system allows to perform a first generation of heavy ion driven target experiments and to test most of the critical issues of a large scale heavy ion fusion driver facility. (orig.)

Performance of the main ring magnet power supply of the KEK 12 GeV proton synchrotron

International Nuclear Information System (INIS)

Sato, H.; Sueno, T.; Toyama, T.; Mikawa, Ml; Toda, M.; Matsumoto, S.; Nakano, M.

1992-01-01

The main ring magnet power supply of the KEK 12 GeV PS consists of several twelve-pulse thyristor rectifiers with dc filters, of two reactive power compensators with tuned ac harmonic filters and of an analog and digital hybrid control system. In order to obtain well defined parameters-such as absolute precision of beam energy, stable beam position, tracking between focusing and bending fields to fix the betatron tune, stable acquisition of extracted beam spill etc.-one wants to operate this large pulsed power supply with high current reproducibility and low residual current ripple. In this paper, several stabilization techniques are applied in order to meet these requirements

Research on degradation of vacuum O-rings under gamma radiation

CERN Document Server

Ino, H; Saitô, Y; Kubo, T; Kinsho, M

2003-01-01

The high-intensity proton accelerator being constructed by JAERI and KEK will generates greater beam power than conventional accelerators. The radiation emission due to beam losses will therefore increase. Since vacuum O-rings installed in the accelerator will be degraded badly by the radiation, there is need to find an O-ring that has more resistant to radiation. To find an O-ring that has better radiation resistant than that of the fluororubber used for conventional accelerators in general, some O-rings which are expected to have enough resistant to the radiation were irradiated, and estimated a degradation by measurement of outgassing rate, hardness, permeation time of helium gas, and an outward observation. Most of the O-rings were irradiated in an oxygen free atmosphere and in the air. The irradiations were carried out at room temperature in Co-60 gamma irradiation facility until a dose of 1 MGy was reached. The radiation resistance of PURE-RUBBER O-ring showed somewhat better than that of the fluororubb...

Bunch coalescing in the Fermilab Main Ring

International Nuclear Information System (INIS)

Wildman, D.; Martin, P.; Meisner, K.; Miller, H.W.

1987-01-01

A new RF system has been installed in the Fermilab Main Ring to coalesce up to 13 individual bunches of protons or antiprotons into a single high-intensity bunch. The coalescing process consists of adiabatically reducing the h=1113 Main Ring RF voltage from 1 MV to less than 1 kV, capturing the debunched beam in a linearized h=53 and h=106 bucket, rotating for a quarter of a synchrotron oscillation period, and then recapturing the beam in a single h=1113 bucket. The new system is described and the results of recent coalescing experiments are compared with computer-generated particle tracking simulations

Present status of device controls and hardware interfaces for the RCNP ring cyclotron

International Nuclear Information System (INIS)

Yamazaki, T.; Tamura, K.; Hosono, K.

1994-01-01

Since the first proton beam from the injector AVF cyclotron was injected to the ring cyclotron in 1991, the computer control system has been used for the beam acceleration of the ring cyclotron. Some device control modules have been updated, and computer configuration has been changed in 1992. Total control system performs basic facilities almost satisfactory under actual cyclotron operation. (author)

Real time data acquisition system for the High Current Test Facility proton accelerator

International Nuclear Information System (INIS)

Langlais, C.E.; Erickson, P.D.; Caissie, L.P.

1975-01-01

A real time data acquisition system was developed to monitor and control the High Current Test Facility Proton Accelerator. It is a PDP-8/E computer system with virtual memory capability that is fully interrupt driven and operates under a real-time, multi-tasking executive. The application package includes mode selection to automatically modify programs and optimize operation under varying conditions. (U.S.)

Protonated serotonin: Geometry, electronic structures and photophysical properties

Science.gov (United States)

Omidyan, Reza; Amanollahi, Zohreh; Azimi, Gholamhassan

2017-07-01

The geometry and electronic structures of protonated serotonin have been investigated by the aim of MP2 and CC2 methods. The relative stabilities, transition energies and geometry of sixteen different protonated isomers of serotonin have been presented. It has been predicted that protonation does not exhibit essential alteration on the S1 ← S0 electronic transition energy of serotonin. Instead, more complicated photophysical nature in respect to its neutral analogue is suggested for protonated system owing to radiative and non-radiative deactivation pathways. In addition to hydrogen detachment (HD), hydrogen/proton transfer (H/PT) processes from ammonium to indole ring along the NH+⋯ π hydrogen bond have been predicted as the most important photophysical consequences of SERH+ at S1 excited state. The PT processes is suggested to be responsible for fluorescence of SERH+ while the HD driving coordinate is proposed for elucidation of its nonradiative deactivation mechanism.

Neutron radiography characterization of an operating proton exchange membrane fuel cell with localized current distribution measurements

International Nuclear Information System (INIS)

Gagliardo, J.J.; Owejan, J.P.; Trabold, T.A.; Tighe, T.W.

2009-01-01

Neutron radiography has proven to be a powerful tool to study and understand the effects of liquid water in an operating fuel cell. In the present work, this experimental method is coupled with locally resolved current and ohmic resistance measurements, giving additional insight into water management and fuel cell performance under a variety of conditions. The effects of varying the inlet humidification level and the current density of the 50 cm 2 cell are studied by simultaneously monitoring electrochemical performance with a 10x10 matrix of current sensors, and liquid water volumes are measured using the National Institute of Standards and Technology (NIST) neutron imaging facility. A counter flow, straight channel proton exchange membrane (PEM) fuel cell is used to demonstrate localized performance loss corresponds to water-filled channels that impede gas transport to the catalyst layer, thereby creating an area that has low current density. Furthermore, certain operating conditions causing excess water accumulation in the channels can result in localized proton resistance increase, a result that can only be accurately observed with combined radiography and distributed electrochemical measurements.

A proton beam delivery system for conformal therapy and intensity modulated therapy

International Nuclear Information System (INIS)

Yu Qingchang

2001-01-01

A scattering proton beam delivery system for conformal therapy and intensity modulated therapy is described. The beam is laterally spread out by a dual-ring double scattering system and collimated by a program-controlled multileaf collimator and patient specific fixed collimators. The proton range is adjusted and modulated by a program controlled binary filter and ridge filters

Production spectra of π+-, K+-, p+- at large angles in proton-proton collisions in the CERN intersecting storage rings

International Nuclear Information System (INIS)

Alper, B.; Boeggild, H.; Booth, P.; Bulos, F.; Carroll, L.J.; Damgaard, G.; Von Dardel, G.; Duff, B.; Hansen, K.H.; Heymann, F.; Jackson, J.N.; Jarlskog, G.; Joensson, L.; Klovning, A.; Leistam, L.; Lillethun, E.; Lohse, E.; Lynch, G.; Manning, G.; Potter, K.; Prentice, M.; Sharp, P.; Sharrock, S.; Oelgaard-Nielsen, S.; Quarrie, D.; Weiss, J.M.

1975-01-01

Results are given on the inclusive production of charged pions, kaons, and nucleons, in proton-proton collisions at c.m. energies from √s=23 to 63 GeV at large angles and for the transverse momentum range 0.1 < psub(T) < 4.8 GeV/c. The dependence of the production spectra on the collision energy √s, the transverse momentum psub(T), and the longitudinal rapidity is discussed. (Auth.)

Longitudinal Single-Bunch Instability in the ILC Damping Rings: Estimate of Current Threshold

International Nuclear Information System (INIS)

Venturini, Marco; Venturini, Marco

2008-01-01

Characterization of single-bunch instabilities in the International Linear Collider (ILC) damping rings (DRs) has been indicated as a high-priority activity toward completion of an engineering design. In this paper we report on a first estimate of the current thresholds for the instability using numerical and analytical models of the wake potentials associated with the various machine components. The numerical models were derived (upon appropriate scaling) from designs of the corresponding components installed in existing machines. The current thresholds for instabilities were determined by numerical solution of the Vlasov equation for the longitudinal dynamics. For the DR baseline lattice as of Feb. 2007 we find the critical current for instability to be safely above the design specifications leaving room for further optimization of the choice of the momentum compaction

Bunch coalescing and bunch rotation in the Fermilab Main Ring: Operational experience and comparison with simulations

International Nuclear Information System (INIS)

Martin, P.S.; Wildman, D.W.

1988-01-01

The Fermilab Tevatron I proton-antiproton collider project requires that the Fermilab Main Ring produce intense bunches of protons and antiprotons for injection into the Tevatron. The process of coalescing a small number of harmonic number h=1113 bunches into a single bunch by bunch-rotating in a lower harmonic rf system is described.The Main Ring is also required to extract onto the antiproton production target bunches with as narrow a time spread as possible. This operation is also discussed. The operation of the bunch coalescing and bunch rotation are compared with simulations using the computer program ESME. 2 refs., 8 figs

EBT ring physics

International Nuclear Information System (INIS)

Uckan, N.A.

1980-04-01

This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers

Energization of the Ring Current through Convection of Substorm Enhancements of the Plasma Sheet Source.

Science.gov (United States)

Menz, A.; Kistler, L. M.; Mouikis, C.; Spence, H. E.; Henderson, M. G.; Matsui, H.

2017-12-01

It has been shown that electric field strength and night-side plasma sheet density are the two best predictors of the adiabatic energy gain of the ring current during geomagnetic storms (Liemohn and Khazanov, 2005). While H+ dominates the ring current during quiet times, O+ can contribute substantially during geomagnetic storms. Substorm activity provides a mechanism to enhance the energy density of O+ in the plasma sheet during geomagnetic storms, which is then convected adiabatically into the inner-magnetosphere. Using the Van Allen Probes data in the the plasma sheet source region (defined as L>5.5 during storms) and the inner magnetosphere, along with LANL-GEO data to identify substorm injection times, we show that adiabatic convection of O+ enhancements in the source region can explain the observed enhancements in the inner magnetosphere. We use the UNH-IMEF electric field model to calculate drift times from the source region to the inner magnetosphere to test whether enhancements in the inner-magnetosphere can be explained by dipolarization driven enhancements in the plasma sheet source hours before.

Magnetization of two coupled rings

International Nuclear Information System (INIS)

Avishai, Y; Luck, J M

2009-01-01

We investigate the persistent currents and magnetization of a mesoscopic system consisting of two clean metallic rings sharing a single contact point in a magnetic field. Many novel features with respect to the single-ring geometry are underlined, including the explicit dependence of wavefunctions on the Aharonov-Bohm fluxes, the complex pattern of two-fold and three-fold degeneracies, the key role of length and flux commensurability, and in the case of commensurate ring lengths the occurrence of idle levels which do not carry any current. Spin-orbit interactions, induced by the electric fields of charged wires threading the rings, give rise to a peculiar version of the Aharonov-Casher effect where, unlike for a single ring, spin is not conserved. Remarkably enough, this can only be realized when the Aharonov-Bohm fluxes in both rings are neither integer nor half-integer multiples of the flux quantum

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes

Directory of Open Access Journals (Sweden)

Oleksandr Makeyev

2016-06-01

Full Text Available Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1-polar electrode with n rings using the (4n + 1-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2 and quadripolar (n = 3 electrode configurations are compared to their constant inter-ring distances counterparts. Finite element method modeling and analytic results are consistent and suggest that increasing inter-ring distances electrode configurations may decrease the truncation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration, the truncation error may be decreased more than two-fold, while for the quadripolar configuration more than a six-fold decrease is expected.

Improving the Accuracy of Laplacian Estimation with Novel Variable Inter-Ring Distances Concentric Ring Electrodes

Science.gov (United States)

Makeyev, Oleksandr; Besio, Walter G.

2016-01-01

Noninvasive concentric ring electrodes are a promising alternative to conventional disc electrodes. Currently, the superiority of tripolar concentric ring electrodes over disc electrodes, in particular, in accuracy of Laplacian estimation, has been demonstrated in a range of applications. In our recent work, we have shown that accuracy of Laplacian estimation can be improved with multipolar concentric ring electrodes using a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2. This paper takes the next step toward further improving the Laplacian estimate by proposing novel variable inter-ring distances concentric ring electrodes. Derived using a modified (4n + 1)-point method, linearly increasing and decreasing inter-ring distances tripolar (n = 2) and quadripolar (n = 3) electrode configurations are compared to their constant inter-ring distances counterparts. Finite element method modeling and analytic results are consistent and suggest that increasing inter-ring distances electrode configurations may decrease the truncation error resulting in more accurate Laplacian estimates compared to respective constant inter-ring distances configurations. For currently used tripolar electrode configuration, the truncation error may be decreased more than two-fold, while for the quadripolar configuration more than a six-fold decrease is expected. PMID:27294933

Electro-optical hybrid slip ring

Science.gov (United States)

Hong, En

2005-11-01

The slip ring is a rotary electrical interface, collector, swivel or rotary joint. It is a physical system that can perform continuous data transfer and data exchange between a stationary and a rotating structure. A slip ring is generally used to transfer data or power from an unrestrained, continuously rotating electro-mechanical system in real-time, thereby simplifying operations and eliminating damage-prone wires dangling from moving joints. Slip rings are widely used for testing, evaluating, developing and improving various technical equipment and facilities with rotating parts. They are widely used in industry, especially in manufacturing industries employing turbo machinery, as in aviation, shipbuilding, aerospace, defense, and in precise facilities having rotating parts such as medical Computerized Tomography (CT) and MRI scanners and so forth. Therefore, any improvement in slip ring technology can impact large markets. Research and development in this field will have broad prospects long into the future. The goal in developing the current slip ring technology is to improve and increase the reliability, stability, anti-interference, and high data fidelity between rotating and stationary structures. Up to now, there have been numerous approaches used for signal and data transfer utilizing a slip ring such as metal contacts, wires, radio transmission, and even liquid media. However, all suffer from drawbacks such as data transfer speed limitations, reliability, stability, electro-magnetic interference and durability. The purpose of the current research is to break through these basic limitations using an optical solution, thereby improving performance in current slip ring applications. This dissertation introduces a novel Electro-Optical Hybrid Slip Ring technology, which makes "through the air" digital-optical communication between stationary and rotating systems a reality with high data transfer speed, better reliability and low interference susceptibility

Search for long-lived heavy charged particles using a ring imaging Cherenkov technique at LHCb

NARCIS (Netherlands)

Aaij, R.; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Cartelle, P. Alvarez; Alves, A. A., Jr.; Amato, S.; Amerio, S.; Amhis, Y.; Everse, LA; Anderlini, L.; Anderson, J.; Andreotti, M.; Andrews, J.E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; d'Argent, P.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Bel, L. J.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bertolin, A.; Bettler, M-O.; Van Beuzekom, Martin; Bien, A.; Bifani, S.; Bird, T.D.; Birnkraut, A.; Bizzeti, A.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borgia, A.; Borsato, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Brett, D.; Britsch, M.; Britton, T.; Brodzicka, J.; Brook, N. H.; Bursche, A.; Buytaert, J.; Cadeddu, S.; Calabrese, R.; Calvi, M.; Calvo Gomez, M.; Campana, P.; Perez, D. H. Campora; Capriotti, L.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carniti, P.; Carson, L.; Carvalho Akiba, K.; Casanova Mohr, R.; Casse, G.; Cassina, L.; Garcia, L. Castillo; Cattaneo, M.; Cauet, Ch; Cavallero, G.; Cenci, R.; Charles, M.; Charpentier, Ph; Chefdeville, M.; Chen, S.; Cheung, S-F.; Chiapolini, N.; Chrzaszcz, M.; Vidal, X. Cid; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Cogoni, V.; Cojocariu, L.; Collazuol, G.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Corvo, M.; Counts, I.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Crocombe, A.; CruzTorres, M.; Cunliffe, S.; Currie, C.R.; D'Ambrosio, C.; Dalseno, J.; David, P. N. Y.; Davis, A.; De Bruyn, K.; De Capua, S.; De Cian, M.; de Miranda, J. M.; Paula, L.E.; da-Silva, W.S.; De Simone, P.; Dean, C-T.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Deleage, N.; Derkach, D.; Deschamps, O.; Dettori, F.; Dey, B.; Di Canto, A.; Di Ruscio, F.; Dijkstra, H.; Donleavy, S.; Dordei, F.; Dorigo, M.; Dosil Suarez, A.; Dossett, D.; Dovbnya, A.; Dreimanis, K.; Dujany, G.; Dupertuis, F.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; ElRifai, I.; Elsasser, Ch.; Ely, S.; Esen, S.; Evans, H. M.; Evans, T. M.; Falabella, A.; Faerber, C.; Farinelli, C.; Farley, N.; Farry, S.; Fay, R.; Ferguson, D.; Fernandez Albor, V.; Ferrari, F.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fol, P.; Fontana, Mark; Fontanelli, F.; Forty, R.; De Aguiar Francisco, O.; Frank, M.; Frei, C.; Frosini, M.; Fu, J.; Furfaro, E.; Torreira, A. Gallas; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Gao, Y.; Garcia Pardinas, J.; Garofoli, J.; Tico, J. Garra; Garrido, L.; Gascon, D.; Carvalho-Gaspar, M.; Gauld, Rhorry; Gavardi, L.; Gazzoni, G.; Geraci, A.; Gerick, D.; Gersabeck, E.; Gersabeck, M.; Gershon, T. J.; Ghez, Ph; Gianelle, A.; Giani, S.; Gibson, V.; Giubega, L.; Gligorov, V. V.; Goebel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.Q.; Gotti, C.; Gandara, M. Grabalosa; Diaz, R. Graciani; Cardoso, L. A. Granado; Grauges, E.; Graverini, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grillo, L.; Gruenberg, O.; Gui, B.; Gushchin, E.; Guz, Yu; Gys, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Hampson, T.; Han, X.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; He, J.; Head, T.; Heijne, V.; Hennessy, K.; Henrard, P.; Henry, L.; Hernando Morata, J. A.; van Herwijnen, E.; Hess, H.M.; Hicheur, A.; Hill, D.; Hoballah, M.; Hombach, C.; Hulsbergen, W.; Humair, T.; Hussain, N.; Hutchcroft, D. E.; Hynds, D.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jalocha, J.; Jans, E.; Jawahery, A.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kandybei, S.; Kanso, W.; Karacson, M.; Karbach, T. M.; Karodia, S.; Kelsey, M. H.; Kenyon, I. R.; Kenzie, M.; Ketel, T.; Khanji, B.; Khurewathanakul, C.; Klaver, S.M.; Klimaszewski, K.; Kochebina, O.; Kolpin, M.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kurek, K.; Kvaratskheliya, T.; La Thi, V. N.; Lacarrere, D.; Lafferty, G. D.; Lai, A.; Lambert, D.M.; Lambert, R. W.; Lanfranchi, G.; Langenbruch, C.; Langhans, B.; Latham, T. E.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J. P.; Lefevre, R.; Leflat, A.; Lefrancois, J.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, Y.; Likhomanenko, T.; Liles, M.; Lindner, R.; Linn, S.C.; Lionetto, F.; Liu, B.; Lohn, S.; Longstaff, I.; Lopes, J. H.; Lucchesi, D.; Luo, H.; Lupato, A.; Luppi, E.; Lupton, O.; Machefert, F.; Machikhiliyan, I. V.; Maciuc, F.; Maev, O.; Malde, S.; Malinin, A.; Manca, G.; Mancinelli, G.; Manning, P.; Mapelli, A.; Maratas, J.; Marchand, J. F.; Marconi, U.; Marin Benito, C.; Marino, P.; Maerki, R.; Marks, J.; Martellotti, G.; Martinelli-Boneschi, F.; Santos, D. Martinez; Martinez-Vidal, F.; Martins Tostes, D.; Massafferri, A.; Matev, R.; Mathe, Z.; Matteuzzi, C.; Mauri, A.; Maurin, B.; Mazurov, A.; McCann, M.; McCarthy, J.; Mcnab, A.; McNulty, R.; McSkelly, B.; Meadows, B. T.; Meier, F.; Meissner, M.; Merk, M.; Milanes, D. A.; Minard, M. N.; Mitzel, D. S.; Molina Rodriguez, J.; Monteil, S.; Morandin, M.; Morawski, P.; Morda, A.; Morello, M. J.; Moron, J.; Morris, A. B.; Mountain, R.; Muheim, F.; Mueller, J.; Mueller, Karl; Mueller, V.; Mussini, M.; Muster, B.; Naik, P.; Nakada, T.; Nandakumar, R.; Nasteva, I.; Needham, M.; Neri, N.; Neubert, S.; Neufeld, N.; Neuner, M.; Nguyen, A. D.; Nguyen, T. D.; Nguyen-Mau, C.; Niess, V.; Niet, R.; Nikitin, N.; Nikodem, T.; Novoselov, A.; O'Hanlon, D. P.; Oblakowska-Mucha, A.; Obraztsov, V.; Ogilvy, S.; Okhrimenko, O.; Oldeman, R.; Onderwater, C. J. G.; Osorio Rodrigues, B.; Otalora Goicochea, J. M.; Otto, E.A.; Owen, R.P.; Oyanguren, A.; Palano, A.; Palombo, F.; Palutan, M.; Panman, J.; Papanestis, A.; Pappagallo, M.; Pappalardo, L.L.; Parkes, C.; Passaleva, G.; Patel, G. D.; Patel, M.; Patrignani, C.; Pearce, D.A.; Pellegrino, A.; Penso, G.; Altarelli, M. Pepe; Perazzini, S.; Perret, P.; Pescatore, L.; Petridis, K.; Petrolini, A.; Olloqui, E. Picatoste; Pietrzyk, B.; Pilar, T.; Pinci, D.; Pistone, A.; Playfer, S.; Plo Casasus, M.; Poikela, T.; Polci, F.; Poluektov, A.; Polyakov, I.; Polycarpo, E.; Popov, A.; Popov, D.; Popovici, B.; Potterat, C.; Price, M. E.; Price, J.D.; Prisciandaro, J.; Pritchard, C.A.; Prouve, C.; Pugatch, V.; Navarro, A. Puig; Punzi, G.; Qian, Y.W.; Quagliani, R.; Rachwal, B.; Rademacker, J. H.; Rakotomiaramanana, B.; Rama, M.; Rangel, M. S.; Raniuk, I.; Rauschmayr, N.; Raven, G.; Redi, F.; Reichert, S.; Reid, M.; dos Reis, A. C.; Ricciardi, S.; Richards, Jennifer S; Rihl, M.; Rinnert, K.; Rives Molina, V.; Robbe, P.; Rodrigues, A. B.; Rodrigues, L.E.T.; Perez, P. Rodriguez; Roiser, S.; Romanovsky, V.; Romero Vidal, A.; Rotondo, M.; Rouvinet, J.; Ruf, T.; Ruiz, van Hapere; Ruiz Valls, P.; Saborido Silva, J. J.; Sagidova, N.; Sail, P.; Saitta, B.; Salustino Guimaraes, V.; Sanchez Mayordomo, C.; Sanmartin Sedes, B.; Santacesaria, R.; Santamarina Rios, C.; Santovetti, E.; Sarti, A.; Satriano, C.; Satta, A.; Saunders, D. M.; Savrina, D.; Schiller, M.; Schindler, R. H.; Schlupp, M.; Schmelling, M.; Schmelzer, T.; Schmidt, B.; Schneider, O.; Schopper, A.; Schune, M. H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Semennikov, A.; Sepp, I.; Serra, N.; Serrano, J.; Sestini, L.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, V.; Shires, A.; Coutinho, R. Silva; Simi, G.; Sirendi, M.; Skidmore, N.; Skillicorn, I.; Skwarnicki, T.; Smith, E.; Smith, E.; Smith, J; Smith, M.; Snoek, H.; Sokoloff, M. D.; Soler, F. J. P.; Soomro, F.; de Souza, D.K.; Souza De Paula, B.; Spaan, B.; Spradlin, P.; Sridharan, S.; Stagni, F.; Stahl, M.; Stahl, S.; Steinkamp, O.; Stenyakin, O.; Sterpka, F.; Stevenson-Moore, P.; Stoica, S.; Stone, S.; Storaci, B.; Stracka, S.; Straticiuc, M.; Straumann, U.; Stroili, R.; Sun, L.; Sutcliffe, W.; Swientek, K.; Swientek, S.; Syropoulos, V.; Szczekowski, M.; Szczypka, P.; Szumlak, T.; T'Jampens, S.; Tekampe, T.; Teklishyn, M.; Tellarini, G.; Teubert, F.; Thomas, C.; Thomas, E.; van Tilburg, J.; Tisserand, V.; Tobin, M. N.; Todd, Jim; Tolk, S.; Tomassetti, L.; Tonelli, D.; Topp-Joergensen, S.; Torr, N.; Tournefier, E.; Tourneur, S.; Trabelsi, K.; Tran, N.T.M.T.; Tresch, M.; Trisovic, A.; Tsaregorodtsev, A.; Tsopelas, P.; Tuning, N.; Garcia, M. Ubeda; Ukleja, A.; Ustyuzhanin, A.; Uwer, U.; Vacca, C.; Vagnoni, V.; Valenti, G.; Vallier, A.; Gomez, R. Vazquez; Vazquez Regueiro, P.; Vazquez Sierra, C.; Vecchi, S.; Velthuis, M.J.; Veltri, M.; Veneziano, G.; Vesterinen, M.; Viaud, B.; Vieira, D.; Vieites Diaz, M.; Vilasis-Cardona, X.; Vollhardt, A.; Volyanskyy, D.; Voong, D.; Vorobyev, A.; Vorobyev, V.; Voss, C.; de Vries, J. A.; Waldi, R.; Wallace, C.; Wallace, R.; Walsh, John; Wandernoth, S.; Wang, J.; Ward, D. R.; Watson, N. K.; Websdale, D.; Weiden, A.; Whitehead, M.; Wiedner, D.; Wilkinson, G.; Wilkinson, M.; Williams, M.; Williams, M.P.; Williams, M.; Wilson, James F; Wimberley, J.; Wishahi, J.; Wislicki, W.; Witek, M.; Wormser, G.; Wotton, S. A.; Wright, S.J.; Wyllie, K.; Xie, Y.; Xu, Z.; Yang, Z.; Yuan, X.; Yushchenko, O.; Zangoli, M.; Zavertyaev, M.; Zhang, L.; Zhang, Y.; Zhelezov, A.; Zhokhov, A.; Zhong, L.

2015-01-01

A search is performed for heavy long-lived charged particles using 3.0 fb(-1) of proton-proton collisions collected at √s = 7 and 8 TeV with the LHCb detector. The search is mainly based on the response of the ring imaging Cherenkov detectors to distinguish the heavy, slow-moving particles from

Molecular architecture of the N-type ATPase rotor ring from Burkholderia pseudomallei.

Science.gov (United States)

Schulz, Sarah; Wilkes, Martin; Mills, Deryck J; Kühlbrandt, Werner; Meier, Thomas

2017-04-01

The genome of the highly infectious bacterium Burkholderia pseudomallei harbors an atp operon that encodes an N-type rotary ATPase, in addition to an operon for a regular F-type rotary ATPase. The molecular architecture of N-type ATPases is unknown and their biochemical properties and cellular functions are largely unexplored. We studied the B. pseudomallei N 1 N o -type ATPase and investigated the structure and ion specificity of its membrane-embedded c-ring rotor by single-particle electron cryo-microscopy. Of several amphiphilic compounds tested for solubilizing the complex, the choice of the low-density, low-CMC detergent LDAO was optimal in terms of map quality and resolution. The cryoEM map of the c-ring at 6.1 Å resolution reveals a heptadecameric oligomer with a molecular mass of ~141 kDa. Biochemical measurements indicate that the c 17 ring is H + specific, demonstrating that the ATPase is proton-coupled. The c 17 ring stoichiometry results in a very high ion-to-ATP ratio of 5.7. We propose that this N-ATPase is a highly efficient proton pump that helps these melioidosis-causing bacteria to survive in the hostile, acidic environment of phagosomes. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

New proton conducting membranes for fuel cell applications

Energy Technology Data Exchange (ETDEWEB)

Sukumar, P.R.

2006-07-01

In order to synthesize proton-conducting materials which retain acids in the membrane during fuel cell operating conditions, the synthesis of poly(vinylphosphonic acid) grafted polybenzimidazole (PVPA grafted PBI) and the fabrication of multilayer membranes are mainly focussed in this dissertation. Synthesis of PVPA grafted PBI membrane can be done according to ''grafting through'' method. In ''grafting through'' method (or macromonomer method), monomer (e.g., vinylphosphonic acid) is radically copolymerized with olefin group attached macromonomer (e.g., allyl grafted PBI and vinylbenzyl grafted PBI). This approach is inherently limited to synthesize graft-copolymer with well-defined architectural and structural parameters. The incorporation of poly(vinylphosphonic acid) into PBI lead to improvements in proton conductivity up to 10-2 S/cm. Regarding multilayer membranes, the proton conducting layer-by-layer (LBL) assembly of polymers by various strong acids such as poly(vinylphosphonic acid), poly(vinylsulfonic acid) and poly(styrenesulfonic acid) paired with basic polymers such as poly(4-vinylimidazole) and poly(benzimidazole), which are appropriate for Proton Exchange Membrane Fuel Cell applications have been described. Proton conductivity increases with increasing smoothness of the film and the maximum measured conductivity was 10-4 S/cm at 25A C. Recently, anhydrous proton-conducting membranes with flexible structural backbones, which show proton-conducting properties comparable to Nafion have been focus of current research. The flexible backbone of polymer chains allow for a high segmental mobility and thus, a sufficiently low glass transition temperature (Tg), which is an essential factor to reach highly conductive systems. Among the polymers with a flexible chain backbone, poly(vinylphosphonic acid), poly(vinylbenzylphosphonic acid), poly(2-vinylbenzimidazole), poly(4-styrenesulfonic acid), poly(4-vinylimidazole), poly

New proton conducting membranes for fuel cell applications

Energy Technology Data Exchange (ETDEWEB)

Sukumar, P R

2006-07-01

In order to synthesize proton-conducting materials which retain acids in the membrane during fuel cell operating conditions, the synthesis of poly(vinylphosphonic acid) grafted polybenzimidazole (PVPA grafted PBI) and the fabrication of multilayer membranes are mainly focussed in this dissertation. Synthesis of PVPA grafted PBI membrane can be done according to ''grafting through'' method. In ''grafting through'' method (or macromonomer method), monomer (e.g., vinylphosphonic acid) is radically copolymerized with olefin group attached macromonomer (e.g., allyl grafted PBI and vinylbenzyl grafted PBI). This approach is inherently limited to synthesize graft-copolymer with well-defined architectural and structural parameters. The incorporation of poly(vinylphosphonic acid) into PBI lead to improvements in proton conductivity up to 10-2 S/cm. Regarding multilayer membranes, the proton conducting layer-by-layer (LBL) assembly of polymers by various strong acids such as poly(vinylphosphonic acid), poly(vinylsulfonic acid) and poly(styrenesulfonic acid) paired with basic polymers such as poly(4-vinylimidazole) and poly(benzimidazole), which are appropriate for Proton Exchange Membrane Fuel Cell applications have been described. Proton conductivity increases with increasing smoothness of the film and the maximum measured conductivity was 10-4 S/cm at 25A C. Recently, anhydrous proton-conducting membranes with flexible structural backbones, which show proton-conducting properties comparable to Nafion have been focus of current research. The flexible backbone of polymer chains allow for a high segmental mobility and thus, a sufficiently low glass transition temperature (Tg), which is an essential factor to reach highly conductive systems. Among the polymers with a flexible chain backbone, poly(vinylphosphonic acid), poly(vinylbenzylphosphonic acid), poly(2-vinylbenzimidazole), poly(4-styrenesulfonic acid), poly(4-vinylimidazole), poly(4-vinylimidazole

Large protonation-gated photochromism of an OPE-embedded difurylperfluorocyclopentene

KAUST Repository

Wolf, Jannic Sebastian

2015-01-01

A recently reported protolytic gating effect on the ring closing reaction of an oligo(phenylene ethynylene) (OPE) embedded difurylperfluorocyclopentene (S) with a dimethylaminophenyl chain link in each of the side arms, was quantitatively analyzed in detail. The reaction system (So, SoH+, SoH2 2+, Sc, ScH+, ScH2 2+) comprising three protolytic forms in both open and closed configuration, is characterized by four protolytic equilibrium constants and six photochemical quantum yields of ring closing and ring opening. The absorption spectra, conductivity, and effective photochemical quantum yields were measured in acetonitrile as functions of solvent acidity varied by addition of trifluoroacetic acid and triethylamine and characterized by an effective pHnon-aq. Based on the derivation of a rigorous method for assessing the individual quantum yields of ring closure and ring opening of the six species, it was shown that it is specifically the second protonation step that is responsible for a more than 10-fold increase in the quantum yield of ring closure.

Magnetic field of the magnetospheric ring current and its dynamics during magnetic storms

International Nuclear Information System (INIS)

Feldstein, Y.I.; Grafe, A.; Pisarsky, V.Yu.; Prigansova, A.; Sumaruk, P.V.

1990-01-01

This review examines models existing in the literature which describe the magnetic field produced by the ring current (DR) at the Earth's surface based on the energy balance equation. The parameters of this equation, the injection function F and decay parameter τ are considered to depend on parameters of the interplanetary medium and the DR intensity. The existing models are shown to be able to describe the DR variations with sufficient accuracy (r.m.s. deviation δ between the experimental and modelled values of DR for 170 magnetic storms is 5 < δ < 15 nT, and the correlation coefficient between the two is 0.85 < r < 1). The models describe that part of the geomagnetic field variation at low latitudes during a magnetic storm that is controlled by the geoeffective characteristics of the interplanetary medium and which thus responds immediately to its variations (the driven part). The values of τ are significantly less during the main phase of a magnetic storm than during the recovery phase. This reflects the difference in the main mechanisms of ion loss from the ring current during the two phases of the storm. These are the interaction of ions with hydromagnetic waves during the main phase of the storm with its intervals of intense plasma injection into the inner magnetosphere, and charge exchange with the cold hydrogen geocorona during the recovery phase. (author)

Ring design of the Prague synchrotron for cancer therapy

Energy Technology Data Exchange (ETDEWEB)

Molodozhentsev, A.; Makoveev, V.; Minashkin, V.; Shevtsov, V.; Sidorov, G. [Joint Inst. for Nuclear Research, Dubna (Russian Federation); Prokesh, K.; Sedlak, J.; Kuzmiak, M. [``Oncology 2000`` Foundation, Prague (Czech Republic)

1998-04-01

The paper presents main elements of a dedicated proton synchrotron for hadron therapy. The beam parameters for active scanning of tumours are discussed. The output energy of the beam should be variable in the range 60-220 MeV. The average current of the proton beam is equal to 10 nA. The repetition rate of the accelerator is chosen of 1 Hz to get a spill time for slow extraction of about 500 ms. The timing cycle of the accelerator including the quasi-adiabatic capture process and acceleration is described. The RF gymnastics is utilized to prepare the unbunched beam for slow extraction. The magnetic elements of the ring, compact RF and VCO systems are presented in the paper. The maximum magnet field of the dipole magnet should be 1.2 T and the maximum magnetic field on the pole of the quadrupole lenses should be less than 1 T. The resonator should work on the first harmonic with a frequency from 1.298 MHz till 4.804 MHz. The length of the resonator should be less than 1 m. The maximum voltage on the accelerator gap should be about 2 kV. (orig.) 5 refs.

Antiproton acceleration in the Fermilab Main Ring and Tevatron

International Nuclear Information System (INIS)

Martin, P.; Dinkel, J.; Ducar, R.

1987-01-01

The operation of the Fermilab Main Ring and Tevatron rf systems for colliding beams physics is discussed. The changes in the rf feedback system required for acceleration of antiprotons, and the methods for achieving proper transfer of both protons and antiprotons are described. Data on acceleration and transfer efficiencies are presented

Quarkonium production in high energy proton-proton and proton-nucleus collisions

International Nuclear Information System (INIS)

Conesa del Valle, Z.; Corcella, G.; Fleuret, F.; Ferreiro, E.G.; Kartvelishvili, V.; Kopeliovich, B.; Lansberg, J.P.; Lourenco, C.; Martinez, G.; Papadimitriou, V.; Satz, H.; Scomparin, E.; Ullrich, T.; Teryaev, O.; Vogt, R.; Wang, J.X.

2011-01-01

We present a brief overview of the most relevant current issues related to quarkonium production in high energy proton-proton and proton-nucleus collisions along with some perspectives. After reviewing recent experimental and theoretical results on quarkonium production in pp and pA collisions, we discuss the emerging field of polarisation studies. Afterwards, we report on issues related to heavy-quark production, both in pp and pA collisions, complemented by AA collisions. To put the work in broader perpectives, we emphasize the need for new observables to investigate the quarkonium production mechanisms and reiterate the qualities that make quarkonia a unique tool for many investigations in particle and nuclear physics.

Development of an external Faraday cup for beam current measurements

International Nuclear Information System (INIS)

Kim, Kye-Ryung; Jung, Myung-Hwan; Ra, Se-Jin; Lee, Seok-Ki

2010-01-01

In general, beam current measurements are very important for many kinds of experiments using highly energetic particle beams at accelerators, such as cyclotrons, linacs, etc. The Faraday cup is known to be one of the most popular beam current measurement tools. We developed an external Faraday cup to measure the beam current at a dedicated beam line for low-flux experiments installed at the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences (KIRAMS). It was designed for external beam current measurements and is composed of a vacuum chamber, an entrance window, a collimator, a electrostatic suppressor ring, and a cup. The window is made of 75-um-thick Kapton film, and the diameter of the collimator is 10 mm or 20 mm. The ring and the cup has 5-cm inner diameters, and the thickness of the bottom of the cup is 2 cm, which is enough to absorb the total proton energy up to 45 MeV. Using this external Faraday cup, we measured the beam current from the cyclotron, and we compared measured flux to the results from film dosimetry using GAF films.

On the Effect of Clamping Pressure and Method on the Current Mapping of Proton Exchange Membrane Water Electrolysis

DEFF Research Database (Denmark)

Al Shakhshir, Saher; Zhou, Fan; Kær, Søren Knudsen

The degradation of the electrochemical reaction of the proton exchange membrane water electrolysis (PEMWE) can be characterized using in-situ current mapping measurements (CMM). CMM is significantly affected by the amount of clamping pressure and method. In this work the current is mapped...

Spin dynamics at level crossing in molecular AF rings probed by NMR

International Nuclear Information System (INIS)

Lascialfari, A.; Borsa, F.; Julien, M.-H.; Micotti, E.; Furukawa, Y.; Jang, Z.H.; Cornia, A.; Gatteschi, D.; Horvatic, M.; Van Slageren, J.

2004-01-01

The low-temperature spin dynamics in molecular rings with a finite number (N≤10) of magnetic ions was studied by means of 1 H NMR. When an external magnetic field (B) induces a crossing between energy levels, peaks are observed in the spin-lattice relaxation rate of protons, 1/T 1 (B), at constant temperature. We discuss similarities and differences in the data from three different rings: Fe10, Fe6:Li and Cr8

Polarizing a stored proton beam by spin flip?

International Nuclear Information System (INIS)

Oellers, D.; Barion, L.; Barsov, S.; Bechstedt, U.; Benati, P.; Bertelli, S.; Chiladze, D.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P.F.; Dietrich, J.; Dolfus, N.; Dymov, S.; Engels, R.; Erven, W.; Garishvili, A.; Gebel, R.; Goslawski, P.

2009-01-01

We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron-proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.

Measurement of the ratio of charged current neutrino cross sections on neutrons and protons in the energy range 1-10 GeV

International Nuclear Information System (INIS)

Lerche, W.; Pohl, M.; Schultze, K.; Derange, B.; Francois, T.; Van Dam, P.; Jaffre, M.; Longuemare, C.; Pascaud, C.; Calimani, E.; Ciampolillo, S.; Mattioli, F.

1978-01-01

The charged current cross-section ratio R = sigma(γ+n)/sigma(γ+p), averaged over the energy range, 1-10 GeV, is determined by two independent methods. The combined value is R = 2.08+-0.15. Semi-inclusive proton production rates on both proton and neutron targets are presented. Event rates of exclusive channels on the proton target are also given. (Auth.)

Conditioning of BPM pickup signals for operations of the Duke storage ring with a wide range of single-bunch current

Science.gov (United States)

Xu, Wei; Li, Jing-Yi; Huang, Sen-Lin; Z. Wu, W.; Hao, H.; P., Wang; K. Wu, Y.

2014-10-01

The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers (FELs), and the High Intensity Gamma-ray Source (HIGS). It is operated with a beam current ranging from about 1 mA to 100 mA per bunch for various operations and accelerator physics studies. High performance operations of the FEL and γ-ray source require a stable electron beam orbit, which has been realized by the global orbit feedback system. As a critical part of the orbit feedback system, the electron beam position monitors (BPMs) are required to be able to precisely measure the electron beam orbit in a wide range of the single-bunch current. However, the high peak voltage of the BPM pickups associated with high single-bunch current degrades the performance of the BPM electronics, and can potentially damage the BPM electronics. A signal conditioning method using low pass filters is developed to reduce the peak voltage to protect the BPM electronics, and to make the BPMs capable of working with a wide range of single-bunch current. Simulations and electron beam based tests are performed. The results show that the Duke storage ring BPM system is capable of providing precise orbit measurements to ensure highly stable FEL and HIGS operations.

Conformational change during photocycle of bacteriorhodopsin and its proton-pumping mechanism.

Science.gov (United States)

Chou, K C

1993-06-01

Based on the recent finding on the structural difference of seven helix bundles in the all-trans and 13-cis bacteriorhodopsins, the distances among the key groups performing the function of proton translocation as well as their microenvironments have been investigated. Consequently, a pore-gated model was proposed for the light-driven proton-pumping mechanism of bacteriorhodopsin. According to this model, the five double-bounded polyene chain in retinal chromophore can be phenomenologically likened to a molecular "lever," whose one end links to a "piston" (the beta-ionone ring) and the other end to a pump "relay station" (the Schiff base). During the photocycle of bacteriorhodopsin, the molecular "lever" is moving up and down as marked by the position change of the "piston," so as to trigger the gate of pore to open and close alternately. When the "piston" is up, the pore-controlled gate is open so that the water channel from Asp-96 to the Schiff base and that from the Schiff base to Asp-85 is established; when the "piston" is down, the pore-controlled gate is closed and the water channels for proton transportation in both the cytoplasmic half and extracellular half are blocked. The current model allows a consistent interpretation of a great deal of experimental data and also provides a useful basis for further investigating the mechanism of proton pumping by bacteriorhodopsin.

Elucidation of the substitution pattern of 9,10-anthraquinones through the chemical shifts of peri-hydroxyl protons

DEFF Research Database (Denmark)

Schripsema, Jan; Danigno, Denise

1996-01-01

In 9,10-anthraquinones the chemical shift of a peri-hydroxyl proton is affected by the substituents in the other benzenoid ring. These effects are additive. They are useful for the determination of substitution patterns and have been used to revise the structures of six previously reported...... anthraquinones containing methoxyl, hydroxyl, methylenedioxy and beta-methyl substituents. Because the chemical shifts of the other protons are hardly affected by substitutions in the other ring, the characteristic chemical shifts for a wide variety of substitution patterns could be derived....

Cherenkov rings from aerogel detected by four large-area hybrid photodiodes

International Nuclear Information System (INIS)

Bellunato, T.; Braem, A.; Buzykaev, A.R.; Calvi, M.; Chesi, E.; Danilyuk, A.F.; Easo, S.; Jolly, S.; Joram, C.; Kravchenko, E.A.; Liko, D.; Matteuzzi, C.; Musy, M.; Negri, P.; Neufeld, N.; Onuchin, A.P.; Seguinot, J.; Wotton, S.

2003-01-01

We report on the results obtained using thick samples of silica aerogel as radiators for a Ring Imaging Cherenkov counter. Four large-diameter hybrid photodiodes with 2048 channels have been used as photon detectors. Pions and protons with momenta ranging from 6 to 10 GeV/c were separated and identified. The number of photoelectrons and the radius of the Cherenkov rings together with the Cherenkov angle resolution were measured. A comparison with a simulation program based on GEANT4 is discussed

Analysis of the wake field effects in the PEP-II storage rings with extremely high currents

Energy Technology Data Exchange (ETDEWEB)

Novokhatski, A., E-mail: novo@slac.stanford.edu; Seeman, J.; Sullivan, M.

2014-01-21

We present the history and analysis of different wake field effects throughout the operational life of the PEP-II SLAC B-factory. Although the impedance of the high and low energy rings is small, the intense high-current beams generated a lot of power. The effects from these wake fields are: heating and damage of vacuum beam chamber elements like RF seals, vacuum valves, shielded bellows, BPM buttons and ceramic tiles; vacuum spikes, vacuum instabilities and high detector background; and beam longitudinal and transverse instabilities. We also discuss the methods used to eliminate these effects. Results of this analysis and the PEP-II experience may be very useful in the design of new storage rings and light sources.

Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

Science.gov (United States)

Thorne, Richard M.; Horne, Richard B.

1994-01-01

Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

Reuse Recycler: High Intensity Proton Stacking at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Adamson, P. [Fermilab

2016-07-17

After a successful career as an antiproton storage and cooling ring, Recycler has been converted to a high intensity proton stacker for the Main Injector. We discuss the commissioning and operation of the Recycler in this new role, and the progress towards the 700 kW design goal.

BERKELEY: ALS ring

Energy Technology Data Exchange (ETDEWEB)

Anon.

1993-06-15

Everybody at Lawrence Berkeley Laboratory's Center for Beam Physics is pleased with the rapid progress in commissioning LBL's Advanced Light Source (ALS) electron storage ring, the foundation for this third-generation synchrotron radiation facility. Designed for a maximum current of 400 mA, the ALS storage ring reached 407 mA just 24 days after storing the first beam on 16 March. ALS construction as a US Department of Energy (DOE) national user facility to provide high-brightness vacuum ultra-violet and soft x-ray radiation began in October 1987. One technical requirement marking project completion was to accumulate a 50-mA current in the storage ring. The ALS passed this milestone on 24 March, a week ahead of the official deadline. Once injected, the electron beam decays quasi-exponentially primarily because of interactions with residual gas molecules in the storage-ring vacuum chamber. Eventually, when the pressure in the vacuum chamber with beam decreases toward the expected operating level of 1 nano Torr, it will only be necessary to refill the storage ring at intervals of four to eight hours. At present the vacuum is improving rapidly as surfaces are irradiated (scrubbed) by the synchrotron radiation itself. At 100 mA, beam lifetime was about one hour (9 April)

BERKELEY: ALS ring

International Nuclear Information System (INIS)

Anon.

1993-01-01

Everybody at Lawrence Berkeley Laboratory's Center for Beam Physics is pleased with the rapid progress in commissioning LBL's Advanced Light Source (ALS) electron storage ring, the foundation for this third-generation synchrotron radiation facility. Designed for a maximum current of 400 mA, the ALS storage ring reached 407 mA just 24 days after storing the first beam on 16 March. ALS construction as a US Department of Energy (DOE) national user facility to provide high-brightness vacuum ultra-violet and soft x-ray radiation began in October 1987. One technical requirement marking project completion was to accumulate a 50-mA current in the storage ring. The ALS passed this milestone on 24 March, a week ahead of the official deadline. Once injected, the electron beam decays quasi-exponentially primarily because of interactions with residual gas molecules in the storage-ring vacuum chamber. Eventually, when the pressure in the vacuum chamber with beam decreases toward the expected operating level of 1 nano Torr, it will only be necessary to refill the storage ring at intervals of four to eight hours. At present the vacuum is improving rapidly as surfaces are irradiated (scrubbed) by the synchrotron radiation itself. At 100 mA, beam lifetime was about one hour (9 April)

Electron Cloud Mitigation in the Spallation Neutron Source Ring

International Nuclear Information System (INIS)

Wei, J.; Blaskiewicz, Michael; Brodowski, J.; Cameron, P.; Davino, Daniele; Fedotov, A.; He, P.; Hseuh, H.; Lee, Y.Y.; Ludewig, H.; Meng, W.; Raparia, D.; Tuozzolo, J.; Zhang, S.Y.; Catalan-Lasheras, N.; Macek, R.J.; Furman, Miguel A.; Aleksandrov, A.; Cousineau, S.; Danilov, V.; Henderson, S.

2008-01-01

The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H - injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron-cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation

Electron-cloud mitigation in the spallation neutron source ring

International Nuclear Information System (INIS)

Wei, J.; Blaskiewicz, M.; Brodowski, J.; Cameron, P.; Davino, D.; Fedotov, A.; He, P.; Hseuh, H.; Lee, Y.Y.; Meng, W.; Raparia, D.; Tuozzolo, J.; Zhang, S.Y.; Danilov, V.; Henderson, S.; Furman, M.; Pivi, M.; Macek, R.

2003-01-01

The Spallation Neutron Source (SNS) accumulator ring is designed to accumulate, via H- injection, protons of 2 MW beam power at 1 GeV kinetic energy at a repetition rate of 60 Hz [1]. At such beam intensity, electron cloud is expected to be one of the intensity-limiting mechanisms that complicate ring operations. This paper summarizes mitigation strategy adopted in the design, both in suppressing electron-cloud formation and in enhancing Landau damping, including tapered magnetic field and monitoring system for the collection of stripped electrons at injection, TiN coated beam chamber for suppression of the secondary yield, clearing electrodes dedicated for the injection region and parasitic on BPMs around the ring, solenoid windings in the collimation region, and planning of vacuum systems for beam scrubbing upon operation

Detection of a weak ring current in a nonaromatic porphyrin nanoring using magnetic circular dichroism.

Science.gov (United States)

Kowalska, Patrycja; Peeks, Martin D; Roliński, Tomasz; Anderson, Harry L; Waluk, Jacek

2017-12-13

We compare the absorption and magnetic circular dichroism (MCD) spectra of a series of porphyrin oligomers - dimer, tetramer, and hexamer - bound in a linear or cyclic fashion. The MCD signal is extremely weak for low energy transitions in the linear oligomers, but it is amplified when the cyclic porphyrin hexamer binds a template, restricting rotational freedom. The appearance of Faraday A terms in the MCD spectra demonstrates the presence of a magnetic moment, and thus, uncompensated electronic current. The value of the excited state magnetic moment estimated from the A term is very low compared with those of monomeric porphyrins, which confirms the nonaromatic character of the cyclic array and the lack of a global ring current in the ground state of the neutral nanoring. DFT calculations predict the absorption and MCD patterns reasonably well, but fail to reproduce the MCD sign inversion observed in substituted monomeric zinc porphyrins ("soft" chromophores). Interestingly, a correct sign pattern is predicted by INDO/S calculations. Analysis of the MCD spectra of the monomeric porphyrin unit allowed us to distinguish between two close-lying lowest energy transitions, which some previous assignments placed further apart. The present results prove the usefulness of MCD not only for deconvolution and assignment of electronic transitions, but also as a sensitive tool for detecting electronic ring currents.

Spin dynamics at level crossing in molecular AF rings probed by NMR

Energy Technology Data Exchange (ETDEWEB)

Lascialfari, A. E-mail: lascialfari@fisicavolta.unipv.it; Borsa, F.; Julien, M.-H.; Micotti, E.; Furukawa, Y.; Jang, Z.H.; Cornia, A.; Gatteschi, D.; Horvatic, M.; Van Slageren, J

2004-05-01

The low-temperature spin dynamics in molecular rings with a finite number (N{<=}10) of magnetic ions was studied by means of {sup 1}H NMR. When an external magnetic field (B) induces a crossing between energy levels, peaks are observed in the spin-lattice relaxation rate of protons, 1/T{sub 1}(B), at constant temperature. We discuss similarities and differences in the data from three different rings: Fe10, Fe6:Li and Cr8.

Dynamics of RF captured cooled proton beams

International Nuclear Information System (INIS)

Kells, W.; Mills, F.

1983-01-01

In the course of electron cooling experiments at the Electron Cooling Ring (ECR) at Fermilab, several peculiar features of the longitudinal phase space of cold protons (200 MeV) captured in RF buckets were observed. Here we present the experimental facts, present a simple theory, and summarize computer simulation results which support the theory and facts

Impact of the storm-time plasma sheet ion composition on the ring current energy density

Science.gov (United States)

Mouikis, C.; Kistler, L. M.; Petrinec, S. M.; Fuselier, S. A.; Cohen, I.

2017-12-01

The adiabatic inward transport of the night-side near-earth ( 6 Re) hot plasma sheet is the dominant contributor to the ring current pressure during storm times. During storm times, the plasma sheet composition in the 6 - 12 Re tail region changes due to O+ entry from the lobes (from the cusp) and the direct feeding from the night side auroral region. In addition, at substorm onset the plasma sheet O+ ions can be preferentially accelerated. We use MMS and observations during two magnetic storms, 5/8/2016 and 7/16/2017, to monitor the composition changes and energization in the 6 - 12 Re plasma sheet region. For both storms the MMS apogee was in the tail. In addition, we use subsequent Van Allen Probe observations (with apogee in the dawn and dusk respectively) to test if the 6-12 Re plasma sheet, observed by MMS, is a sufficient source of the O+ in the ring current. For this we will compare the phase space density (PSD) of the plasma sheet source population and the PSD of the inner magnetosphere at constant magnetic moment values as used in Kistler et al., [2016].

Dst and a map of average equivalent ring current: 1958-2007

Science.gov (United States)

Love, J. J.

2008-12-01

A new Dst index construction is made using the original hourly magnetic-observatory data collected over the years 1958-2007; stations: Hermanus South Africa, Kakioka Japan, Honolulu Hawaii, and San Juan Puerto Rico. The construction method we use is generally consistent with the algorithm defined by Sugiura (1964), and which forms the basis for the standard Kyoto Dst index. This involves corrections for observatory baseline shifts, subtraction of the main-field secular variation, and subtraction of specific harmonics that approximate the solar-quiet (Sq) variation. Fourier analysis of the observatory data reveals the nature of Sq: it consists primarily of periodic variation driven by the Earth's rotation, the Moon's orbit, the Earth's orbit, and, to some extent, the solar cycle. Cross coupling of the harmonics associated with each of the external periodic driving forces results in a seemingly complicated Sq time series that is sometimes considered to be relatively random and unpredictable, but which is, in fact, well described in terms of Fourier series. Working in the frequency domain, Sq can be filtered out, and, upon return to the time domain, the local disturbance time series (Dist) for each observatory can be recovered. After averaging the local disturbance time series from each observatory, the global magnetic disturbance time series Dst is obtained. Analysis of this new Dst index is compared with that produced by Kyoto, and various biases and differences are discussed. The combination of the Dist and Dst time series can be used to explore the local-time/universal-time symmetry of an equivalent ring current. Individual magnetic storms can have a complicated disturbance field that is asymmetrical in longitude, presumably due to partial ring currents. Using 50 years of data we map the average local-time magnetic disturbance, finding that it is very nearly proportional to Dst. To our surprise, the primary asymmetry in mean magnetic disturbance is not between

Beam-beam force and storage ring parameters

International Nuclear Information System (INIS)

Herrera, J.C.

1979-01-01

The fundamental aspects of the beam--beam force as it occurs in Intersecting Storage Rings are reported. The way in which the effect of the beam--particle electromagnetic force (weak--strong interaction) is different in the case of unbunched proton beams which cross each other at an angle (as in the ISR and in ISABELLE) is shown, as compared to the case of electron--positron beams where bunches collide head-on

DEVELOPMENT OF TITANIUM NITRIDE COATING FOR SNS RING VACUUM CHAMBERS

International Nuclear Information System (INIS)

HE, P.; HSEUH, H.C.; MAPES, M.; TODD, R.; WEISS, D.

2001-01-01

The inner surface of the ring vacuum chambers of the US Spallation Neutron Source (SNS) will be coated with ∼100 nm of Titanium Nitride (TiN). This is to minimize the secondary electron yield (SEY) from the chamber wall, and thus avoid the so-called e-p instability caused by electron multipacting as observed in a few high-intensity proton storage rings. Both DC sputtering and DC-magnetron sputtering were conducted in a test chamber of relevant geometry to SNS ring vacuum chambers. Auger Electron Spectroscopy (AES) and Rutherford Back Scattering (RBS) were used to analyze the coatings for thickness, stoichiometry and impurity. Excellent results were obtained with magnetron sputtering. The development of the parameters for the coating process and the surface analysis results are presented

The 400 GeV proton synchrotron

International Nuclear Information System (INIS)

1976-05-01

A general account is given of the 400-GeV proton synchrotron, known as Super Proton Synchrotron (SPS), of the European Organization for Nuclear Research (CERN) at Geneva. A brief chapter on the history of the project covers the steps leading to the earlier plan for a 300-GeV accelerator at a new CERN laboratory elsewhere in Europe, abandoned in 1971 in favour of the present machine, and the progress of construction of the latter. The general features of the SPS design are outlined, illustrated by an aerial view of the CERN site, a plan of the SPS, and interior views of the SPS ring tunnel and main control room. (WSN)

Positron Options for the Linac-Ring LHeC

CERN Document Server

Zimmermann, F; Papaphilippou, Y; Schulte, D; Sievers, P; Rinolfi, L; Variola, A; Zomer, F; Braun, H H; Yakimenko, V; Bulyak, E V; Klein, M

2012-01-01

The full physics program of a future Large Hadron electron Collider (LHeC) [1] requires both pe+ and pe− collisions. For a pulsed 140-GeV or an ERL-based 60-GeV Linac-Ring LHeC this implies a challenging rate of, respectively, about 1.8 × 1015 or 4.4 × 1016 e+/s at the collision point, which is about 300 or 7000 times the rate previously obtained, at the SLAC Linear Collider (SLC). We consider providing this e+ rate through a combination of measures: (1) Reducing the required production rate from the e+ target through colliding e+ (and the LHC protons) several times before deceleration, by reusing the e+ over several acceleration/deceleration cycles, and by cooling them, e.g., with a compact tri-ring scheme or a conventional damping ring in the SPS tunnel. (2) Using an advanced target, e.g., W-granules, rotating wheel, slicedrod converter, or liquid metal jet, for converting gamma rays to e+. (3) Selecting the most powerful of several proposed gamma sources, namely Compton ERL, Compton storage ring, coher...

RHIC polarized proton-proton operation at 100 GeV in Run 15

International Nuclear Information System (INIS)

Schoefer, V.; Aschenauer, E. C.; Atoian, G.; Blaskiewicz, M.; Brown, K. A.; Bruno, D.; Connolly, R.; D Ottavio, T.; Drees, K. A.; Dutheil, Y.; Fischer, W.; Gardner, C.; Gu, X.; Hayes, T.; Huang, H.; Laster, J.; Liu, C.; Luo, Y.; Makdisi, Y.; Marr, G.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R.; Marusic, A.; Minty, M.; Montag, C.; Morris, J.; Narayan, G.; Nemesure, S.; Pile, P.; Poblaguev, A.; Ranjbar, V.; Robert-Demolaize, G.; Roser, T.; Schmidke, W. B.; Severino, F.; Shrey, T.; Smith, K.; Steski, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; White, S.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S. Y.

2015-01-01

The first part of RHIC Run 15 consisted of ten weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance. The largest effort consisted in commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a beam-beam compensation with the e-lens, which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic RF cature scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires.

First high-power model of the annular-ring coupled structure for use in the Japan Proton Accelerator Research Complex linac

Directory of Open Access Journals (Sweden)

Hiroyuki Ao

2012-01-01

Full Text Available A prototype cavity for the annular-ring coupled structure (ACS for use in the Japan Proton Accelerator Research Complex (J-PARC linac has been developed to confirm the feasibility of achieving the required performance. This prototype cavity is a buncher module, which includes ten accelerating cells in total. The ACS cavity is formed by the silver brazing of ACS half-cell pieces stacked in a vacuum furnace. The accelerating cell of the ACS is surrounded by a coupling cell. We, therefore, tuned the frequencies of the accelerating and coupling cells by an ultraprecision lathe before brazing, taking into account the frequency shift due to brazing. The prototype buncher module was successfully conditioned up to 600 kW, which corresponds to an accelerating field that is higher than the designed field of 4.1  MV/m by 30%. We describe the frequency-tuning results for the prototype buncher module and its high-power conditioning.

Colliding or co-rotating ion beams in storage rings for EDM search

International Nuclear Information System (INIS)

Koop, I A

2015-01-01

A new approach to search for and measure the electric dipole moment (EDM) of the proton, deuteron and some other light nuclei is presented. The idea of the method is to store two ion beams, circulating with different velocities, in a storage ring with crossed electric and magnetic guiding fields. One beam is polarized and its EDM is measured using the so-called ‘frozen spin’ method. The second beam, which is unpolarized, is used as a co-magnetometer, sensitive to the radial component of the ring’s magnetic field. The particle’s magnetic dipole moment (MDM) couples to the radial magnetic field and mimics the EDM signal. Measuring the relative vertical orbit separation of the two beams, caused by the presence of the radial magnetic field, one can control the unwanted MDM spin precession. Examples of the parameters for EDM storage rings for protons and other species of ions are presented. The use of crossed electric and magnetic fields helps to reduce the size of the ring by a factor of 10–20. We show that the bending radius of such an EDM storage ring could be about 2–3 m. Finally, a new method of increasing the spin coherence time, the so-called ‘spin wheel’, is proposed and its applicability to the EDM search is discussed. (paper)

Simulation of spin dynamics to measure electric dipole moments in storage rings

Energy Technology Data Exchange (ETDEWEB)

Rosenthal, Marcel; Lehrach, Andreas [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Kernphysik; Collaboration: JEDI-Collaboration

2013-07-01

CP violation in the baryon sector, which is predicted by the Standard Model of Particle Physics, is too small to explain the matter and antimatter asymmetry in our universe. Permanent Electric Dipole Moments (EDMs) violate both P and T symmetries and are therefore, through the CPT theorem, also CP violating. No direct EDM measurements for protons, deuterons and light nuclei have been performed up to now. The JEDI collaboration at Forschungszentrum Juelich (FZJ) and the BNL-EDM collaboration at Brookhaven National Laboratory (BNL) pursue the goal to measure the EDMs of these particles in dedicated storage rings. Therefore different approaches are studied to reach an ultimate sensitivity of 10{sup -29} e.cm. A first direct measurement of the proton and deuteron EDM at a sensitivity level of 10{sup -24} e.cm will be performed in the existing conventional storage ring at FZJ, the Cooler Synchrotron COSY. Particle tracking simulations to explore the motion-correlated spin dynamics are a crucial part of feasibility studies of the planned storage ring EDM experiments. In a first step, a benchmarking of simulation codes with measurements at the Cooler Synchrotron COSY is performed.

Studies and calculations of transverse emittance growth in proton storage rings

International Nuclear Information System (INIS)

Mane, S.R.; Jackson, G.

1989-01-01

When high energy storage rings are used to collide beams of particles and antiparticles for high energy physics experiments, it is important to obtain as high an integrated luminosity as possible. Reduction of integrated luminosity can arise from several factors, in particular from growth of the transverse beam sizes (transverse emittances). We have studied the problem of transverse emittance growth in high energy storage rings caused by random dipole noise kicks to the beam. A theoretical formula for the emittance growth rate is derived, and agreement is obtained with experimental measurements where noise of known amplitude and power spectrum was deliberately injected into the Fermilab Tevatron, to kick the beam randomly. In the experiment, phase noise was introduced into the Tevatron rf system, and the measured dependence of horizontal emittance growth on phase noise amplitude is compared against the theoretically derived response. (orig.)

Interaction Region Design for a Ring-Ring LHeC

CERN Document Server

Thompson, L N S; Bernard, N R; Fitterer, M; Holzer, B; Klein, M; Kostka, P

2011-01-01

tively low energy and moderately high intensity provides high luminosity TeV-scale e-p collisions at one of the LHC interaction points, running simultaneously with existing experiments. Two designs are studied; an electron ring situated in the LHC tunnel, and an electron linac. The focus of this paper is on the ring design. Designing an e-p machine presents interesting accelerator physics and design challenges, particularly when considering the interaction region. These include coupled optics, beam separation and unconventional mini-beta focusing schemes. Designs are constrained by an array of interdependent factors, including beam-beam interaction, detector dimensions and acceptance, luminosity and synchrotron radiation. Methods of addressing these complex issues are discussed. The current designs for the LHeC Ring-Ring interaction region and long straight section are presented and discussed, in the context of the project goals and design challenges encountered. Future developments and work are also discusse...

Amide proton transfer imaging in clinics: Basic concepts and current and future use in brain tumors and stoke

Energy Technology Data Exchange (ETDEWEB)

Park, Ji Eun [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Jahng, Geon Ho [Dept. of Radiology, Kyung Hee University Hospital at Gangdong, College of Medicine, Kyung Hee University, Seoul (Korea, Republic of); Jeong, Ha Kyu [Philips Korea, Seoul (Korea, Republic of)

2016-12-15

Amide proton transfer (APT) imaging is gaining attention as a relatively new in vivo molecular imaging technique that has higher sensitivity and spatial resolution than magnetic resonance spectroscopy imaging. APT imaging is a subset of the chemical exchange saturation transfer mechanism, which can offer unique image contrast by selectively saturating protons in target molecules that get exchanged with protons in bulk water. In this review, we describe the basic concepts of APT imaging, particularly with regard to the benefit in clinics from the current literature. Clinical applications of APT imaging are described from two perspectives: in the diagnosis and monitoring of the treatment response in brain glioma by reflecting endogenous mobile proteins and peptides, and in the potential for stroke imaging with respect to tissue acidity.

Persistent current in triangle silicene rings with spin–orbit interaction

Energy Technology Data Exchange (ETDEWEB)

Xu, Ning, E-mail: nxu@ycit.cn [Department of Physics, Yancheng Institute of Technology, Yancheng 224051 (China); Zhang, Haiyang; Wu, Xiuqiang; Bai, Yujie [Department of Physics, Yancheng Institute of Technology, Yancheng 224051 (China); Ding, Jianwen, E-mail: jwding@xtu.edu.cn [Department of Physics, Xiangtan University, Xiangtan 411105 (China)

2017-06-28

The energy spectrum and magnetic response of triangle silicene rings (TSRs) are investigated within the tight-binding model. It is shown that the flux-dependent energy spectrum is divided into bands, with three levels per band, owing to the three-fold rotational symmetry structure of TSRs. The zigzag TSRs are metallic, exhibiting either diamagnetic or paramagnetic response depending on the size of inner ring radius. Armchair TSRs are semiconducting, exhibiting diamagnetic response. Taking into account the intrinsic spin–orbit interaction, the magnetic-field-driven spin-up electrons flow anticlockwise around the TSRs and the spin-down electrons flow clockwise around the TSRs. Additionally, paramagnetism–diamagnetism or diamagnetism–paramagnetism transitions are observed with the increase of exchange field. The results may be very helpful for the design and application of TSR-based nanodevices. - Highlights: • The zigzag TSRs are metallic. • Armchair TSRs which exhibit diamagnetic response are semiconducting. • The spin-up electrons flow anticlockwise and spin-down electrons flow clockwise around the rings.

Comparative analysis of long-time variations of multicomponent ion ring current according to data of geostationary Gorizont satellite

International Nuclear Information System (INIS)

Kovtyukh, A.S.; Panasyuk, M.I.; Vlasova, N.A.; Sosnovets, Eh.N.

1990-01-01

Long-time variations of the fluxes of the H + , [N,O] 2+ and [C,N,O] 6 6 + ions with energy E/Q∼60-120 keV/e measured by the GORIZONT (1985-07A) satellite in the geostationary orbit at noon time are analyzed. The results are dsicussed and are compared with current models of the formation of the Earth's ion ring current

Role of the lifetime of ring current particles on the solar wind-magnetosphere power transfer during the intense geomagnetic storm of 28 August 1978

International Nuclear Information System (INIS)

Gonzalez, W.D.; Gonzalez, A.L.C.; Lee, L.C.

1990-01-01

For the intense magnetic storms of 28 August 1978 it is shown that the power transfer from the solar wind to the magnetosphere is well represented by the expression obtained by Vasyliunas et al. (1982, Planet. Space Sci. 30, 359) from dimensional analysis, but this representation becomes improved when such an expression is modified by a factor due to an influence of the lifetime of ring current particles as suggested by Lee and Akasofu (1984, Planet. Space Sci. 32, 1423). During a steady state regime of the ring current evolution of this storm, our study suggests that the power transfer depends on the solar wind density, the transverse component of the IMF (Interplanetary magnetic field) (with respect to the Sun-Earth line) and also, explicitly, on the time constant for ring current energy decay, but not on the solar wind speed. (author)

Investigation of the double exponential in the current-voltage characteristics of silicon solar cells. [proton irradiation effects on ATS 1 cells

Science.gov (United States)

Wolf, M.; Noel, G. T.; Stirn, R. J.

1977-01-01

Difficulties in relating observed current-voltage characteristics of individual silicon solar cells to their physical and material parameters were underscored by the unexpected large changes in the current-voltage characteristics telemetered back from solar cells on the ATS-1 spacecraft during their first year in synchronous orbit. Depletion region recombination was studied in cells exhibiting a clear double-exponential dark characteristic by subjecting the cells to proton irradiation. A significant change in the saturation current, an effect included in the Sah, Noyce, Shockley formulation of diode current resulting from recombination in the depletion region, was caused by the introduction of shallow levels in the depletion region by the proton irradiation. This saturation current is not attributable only to diffusion current from outside the depletion region and only its temperature dependence can clarify its origin. The current associated with the introduction of deep-lying levels did not change significantly in these experiments.

Recent results from the CELSIUS/WASA collaboration on meson production in proton-hydrogen collisions

International Nuclear Information System (INIS)

Bilger, R.; Bondar, A.; Brodowski, W.; Calen, H.; Clement, H.; Dyring, J.; Ekstroem, C.; Fransson, K.; Gustafsson, L.; Haeggstroem, S.; Hoeistad, B.; Johanson, J.; Johansson, A.; Johansson, T.; Kilian, K.; Kullander, S.; Kupsc, A.; Kuzmin, A.; Marciniewski, P.; Morosov, B.; Moertsell, A.; Oelert, W.; Povtorejko, A.; Ruber, R.J.M.Y.; Schuberth, U.; Sefzick, T.; Sidorov, V.; Shwartz, B.; Sopov, V.; Stepaniak, J.; Sukhanov, A.; Sukhanov, A.; Tchernychev, V.; Turowiecki, A.; Wagner, G.; Wilhelmi, Z.; Zabierowski, J.; Zernov, A.; Zlomanczuk, J.

1999-01-01

Different π and η meson production channels in proton-proton and proton-deuteron collisions have been studied at the CELSIUS storage ring using an internal cluster-jet target setup [1]. During the last years more emphasis has been put on ππ and all but one of the possible channels in proton-proton collisions have been studied. Recently also the quasi-free p+n→d+η reaction cross section has been measured at threshold using 1295 MeV protons and target deuterium. Excess energies from threshold to 10 MeV in the center of mass of the final dη system were covered. Approaching the threshold the cross section is enhanced compared to phase-space expectations. This behaviour is typical for a strong final-state interaction

Feedback to suppress beam instabilities in future proton rings

International Nuclear Information System (INIS)

Lambertson, G.R.

1985-05-01

Criteria for the design of feedback systems to suppress coherent beam instabilities are presented. These address starting amplitudes, diffusion from noise during damping or long storage, and choice of kicker. As a model for future accelerators, specifications of the proposed 20 TeV SSC are used to calculate parameters of systems to control expected instabilities. A scenario and hardware to stabilize the transverse mode-coupling instability is examined. The scale of the systems is large but not out of scale with the large ring. 9 refs., 4 tabs

The current status of development of the electron and proton telescope for Solar Orbiter

Energy Technology Data Exchange (ETDEWEB)

Steinhagen, Jan; Kulkarni, Shrinivasrao; Boden, Sebastian; Martin-Garcia, Cesar; Boettcher, Stephan; Schuster, Bjoern; Seimetz, Lars; Wimmer-Schweingruber, Robert F. [IEAP, Christian-Albrechts-Universitaet zu Kiel (Germany)

2013-07-01

ESA's Solar Orbiter mission, scheduled for launch in January 2017, will study how the sun creates the inner heliosphere. Therefore, the spacecraft will perform in situ and remote sensing measurements of the sun on a high inclination orbit with a perihelion of about 60 solar radii, making it possible to observe the poles of the sun from nearby. The Energetic Particle Detector suite on-board of Solar Orbiter will measure particles of a wide energy range and from multiple directions. One of the important sensors of the EPD suite is the Electron and Proton Telescope. It consists of two antiparallel telescopes with two silicon detectors respectively and is designed to detect electrons between 20 - 400 keV and protons from 20 keV to 7 MeV. EPT relies on a magnet/foil technique to discriminate between electrons and protons. Its design is driven by mass allocation, the thermal environment, power consumption and electronic noise; especially the magnet system must guarantee stray fields low enough to be compliant with the Solar Orbiter EMC requirements. Here, we present the current status of the Structural/Thermal Model and Engineering Model assembly as well as the integration and testing of the prototype.

Elementary design of a 30 TeV on 30 TeV proton antiproton collider

International Nuclear Information System (INIS)

Kondo, Takahiko

1984-01-01

A crude conceptual design was made for a 30TeV on 30TeV antiproton-proton collider. The choice of energy and antiproton-proton (instead of PP) are somewhat arbitrary. The basic parameters of the main ring are listed in a table; the bending radius, ring radius and circumference are 11.1km, 14.4km, and 90.6km, respectively; 7680 dipole magnets with maximum field of 9 Tesla; 1280 quadrupole magnets with maximum gradient of 200Tesla/m. The development of high-field, low-heat loss dipoles and quadrupoles are essential, together with the consideration for their mass production method. On the other hand, the possibility of obtaining antiproton-proton luminosity exceeding 10 32 /cm 2 sec is suggested without any fundamental limitation. With such high luminosity, however, it should be pointed out that particle detectors must face their limitation due to extremely high rate, high multiplicity interaction, requiring large steps of detector research and development efforts. (Aoki, K.)

Proton therapy physics

CERN Document Server

2012-01-01

Proton Therapy Physics goes beyond current books on proton therapy to provide an in-depth overview of the physics aspects of this radiation therapy modality, eliminating the need to dig through information scattered in the medical physics literature. After tracing the history of proton therapy, the book summarizes the atomic and nuclear physics background necessary for understanding proton interactions with tissue. It describes the physics of proton accelerators, the parameters of clinical proton beams, and the mechanisms to generate a conformal dose distribution in a patient. The text then covers detector systems and measuring techniques for reference dosimetry, outlines basic quality assurance and commissioning guidelines, and gives examples of Monte Carlo simulations in proton therapy. The book moves on to discussions of treatment planning for single- and multiple-field uniform doses, dose calculation concepts and algorithms, and precision and uncertainties for nonmoving and moving targets. It also exami...

A Ring Imaging Cerenkov detector for the CERN OMEGA spectrometer

International Nuclear Information System (INIS)

Apsimon, R.J.; Cowell, J.; Flower, P.S.

1984-12-01

A large acceptance Ring Imaging Cerenkov detector has been constructed for use at the CERN Omega Spectrometer. The design of the detector is discussed, with attention paid to its principal components, and preliminary results are given which show that the detector is capable of identifying pions and protons at 100 GeV/c. (author)

Anisotropic amplification of proton transport in proton exchange membrane fuel cells

Science.gov (United States)

Thimmappa, Ravikumar; Fawaz, Mohammed; Devendrachari, Mruthyunjayachari Chattanahalli; Gautam, Manu; Kottaichamy, Alagar Raja; Shafi, Shahid Pottachola; Thotiyl, Musthafa Ottakam

2017-07-01

Though graphene oxide (GO) membrane shuttles protons under humid conditions, it suffer severe disintegration and anhydrous conditions lead to abysmal ionic conductivity. The trade-off between mechanical integrity and ionic conductivity challenge the amplification of GO's ionic transport under anhydrous conditions. We show anisotropic amplification of GO's ionic transport with a selective amplification of in plane contribution under anhydrous conditions by doping it with a plant extract, phytic acid (PA). The hygroscopic nature of PA stabilized interlayer water molecules and peculiar geometry of sbnd OH functionalities around saturated hydrocarbon ring anisotropically enhanced ionic transport amplifying the fuel cell performance metrics.

Enhancements of the critical currents of YBaCuO single crystals by neutron (n) and proton (p) irradiation

International Nuclear Information System (INIS)

Vlcek, B.M.; Frischherz, M.C.; Vishwanathan, H.K.; Welp, U.; Crabtree, G.W.; Kirk, M.A.

1992-01-01

We present results of magnetization hysteresis and T c measurements of neutron and proton irradiated YBaCuO single crystals. The crystals used for comparison were irradiated to a fluence of 2x10 7 n/cm 2 (n,E > 0.1MeV) and 1x10 16 p/cm 2 (p,E=3.5MeV). The critical currents at 1T and 10K are enhanced by a factor of 5 for the neutron irradiated and a factor of 9 for the proton irradiated sample respectively. After irradiation the crystals were annealed at 100, 200 and 300C for 8h each in air. Following each annealing step the critical temperature and the magnetization hysteresis at 10 and 70K was measured. Upon annealing, we observe a decrease of the critical currents, which is more pronounced for the proton irradiated sample. This decrease is related to the removal of point defects or their small clusters. Thus, their contribution to pinning can be studied. The critical temperature decreases after both types of irradiation by about 0.5K and is fully recovered after annealing

Proton-proton elastic scattering measurements at COSY

Energy Technology Data Exchange (ETDEWEB)

Bagdasarian, Zara [Forschungszentrum Juelich, Juelich (Germany); Tbilisi State University, Tbilisi (Georgia); Collaboration: ANKE-Collaboration

2014-07-01

To construct the reliable phase shift analysis (PSA) that can successfully describe the nucleon-nucleon (NN) interaction it is necessary to measure variety of experimental observables for both proton-proton (pp) and neutron-proton (np) elastic scattering. The polarized beams and targets at COSY-ANKE facility allow a substantial contribution to the existing database. The experiment was carried out in April 2013 at ANKE using a transversely polarized proton beam incident on an unpolarized hydrogen cluster target. Six beam energies of T{sub p}=0.8,1.6,1.8,2.0,2.2,2.4 GeV were used. The aim of this talk is to present the preliminary results for the analyzing power (A{sub y}) for the pp elastic scattering in the so-far unexplored 5 <θ{sub cm}<30 angular range. Our measurements are also compared to the world data and current partial wave solutions.

Electron-muon coincidences in proton-proton collisions at the CERN Intersecting Storage Rings

CERN Document Server

Clark, A G; Darriulat, Pierre; Eggert, K; Hungerbühler, V; Jenni, Peter; Lapuyade, C; Modis, T; Pérez, P; Renshall, H; Richter, Burton; Smadja, G; Strauss, J; Strolin, P; Tarnopolsky, G J; Teiger, J; Tur, C; Vialle, J P; Zaccone, Henri; Zallo, A; Zylberstejn, A

1978-01-01

In an experiment carried out at the CERN Intersecting Storage Rings with a highly selective electron spectrometer system and a magnetized iron filter to detect muons, the authors have observed 32+or-16 dilepton events of the type p+p to mu /sup +or-/+e/sup -or+/+... The integrated luminosity of the experiment was (2.0+or-0.1)*10/sup 37/ cm /sup -2/, and the over-all detection efficiency 0.14+or-0.07. Interpreting this signal as due to charmed meson-pair production, the authors estimate a model-dependent acceptance of 6.5*10/sup -5/ per event, and a cross-section sigma (p+p to D+D+...)=(18+or-9) mu b, with a scale uncertainty of 50% due to the detection efficiency. (9 refs).

Electron ring design for HERA, including spin-matching

International Nuclear Information System (INIS)

Skuja, A.; Hand, L.; Steffen, K.; Barber, D.

1984-01-01

A. Skuja has been working in collaboration with Professor Lou Hand in obtaining an optics for the electron ring at HERA that satisfies the usual constraints of an electron storage ring, but in addition allows longitudinal polarization in the interaction region without depolarizing the electron beam completely. This collaboration effort grew out of their work on a possible electron ring at Fermilab. When this project was degraded in priority at Fermilab, they turned their attention to the HERA project at DESY. The HERA project will have an electron ring of about 30 GeV e - (or e + ) incident on 800 GeV protons. Recently it has been decided that the collisions should be head on (0 0 crossing), although all previous designs had a crossing angle of the 2 beams of 20 mrad. Professors Hand and Skuja implemented a complete program in the last year and a half that could fit the usual Turis parameters as well as the so called 12 spin-matching conditions of Chao and Yukoya for all possible machine elements including solenoids. The program has the possibility of fully coupling vertical and horizontal motion using the usual eigenvalue method

The first acceleration test of polarized protons in KEK PS

International Nuclear Information System (INIS)

Hiramatsu, Shigenori; Sato, Hikaru; Toyama, Takeshi

1984-03-01

The outline of the polarized proton acceleration project at KEK and the results of the first acceleration test are described. Depolarization in the 500 MeV booster synchrotron was investigated as the first step of this program. The beam polarization was measured in the 20 MeV beam transport line from the linac to the booster and in the main ring at the injection energy. About 40 % of the linac beam polarization was kept in the main ring. This acceleration test encouraged us to proceed with this program. (author)

A short review of our current understanding of the development of ring faults during collapse caldera formation

Directory of Open Access Journals (Sweden)

Adelina eGeyer

2014-09-01

Full Text Available The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical and experimental studies. Nonetheless, even if there is a tendency to go for a general and comprehensive caldera dynamics model, some key aspects remain unclear, controversial or completely unsolved. This is the case of ring fault nucleation points and propagation and dip direction. Since direct information on calderas’ deeper structure comes mainly from partially eroded calderas or few witnessed collapses, ring faults layout at depth remains still uncertain. This has generated a strong debate over the detailed internal fault and fracture configuration of a caldera collapse and, in more detail, how ring faults initiate and propagate. We offer here a very short description of the main results obtained by those analogue and theoretical/mathematical models applied to the study of collapse caldera formation. We place special attention on those observations related to the nucleation and propagation of the collapse-controlling ring faults. This summary is relevant to understand the current state-of-the-art of this topic and it should be taken under consideration in future works dealing with collapse caldera dynamics.

Topological rings

CERN Document Server

Warner, S

1993-01-01

This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.

Combined convective and diffusive modeling of the ring current and radiation belt electron dynamics using the VERB-4D code

Science.gov (United States)

Aseev, N.; Shprits, Y.; Drozdov, A.; Kellerman, A. C.; Wang, D.

2017-12-01

Ring current and radiation belts are key elements in the global dynamics of the Earth's magnetosphere. Comprehensive mathematical models are useful tools that allow us to understand the multiscale dynamics of these charged particle populations. In this work, we present results of simulations of combined ring current - radiation belt electron dynamics using the four-dimensional Versatile Electron Radiation Belt (VERB-4D) code. The VERB-4D code solves the modified Fokker-Planck equation including convective terms and models simultaneously ring current (1 - 100 keV) and radiation belt (100 keV - several MeV) electron dynamics. We apply the code to the number of geomagnetic storms that occurred in the past, compare the results with different satellite observations, and show how low-energy particles can affect the high-energy populations. Particularly, we use data from Polar Operational Environmental Satellite (POES) mission that provides a very good MLT coverage with 1.5-hour time resolution. The POES data allow us to validate the approach of the VERB-4D code for modeling MLT-dependent processes such as electron drift, wave-particle interactions, and magnetopause shadowing. We also show how different simulation parameters and empirical models can affect the results, making a particular emphasis on the electric and magnetic field models. This work will help us reveal advantages and disadvantages of the approach behind the code and determine its prediction efficiency.

Prototype moving-ring reactor

International Nuclear Information System (INIS)

Smith, A.C. Jr.; Ashworth, C.P.; Abreu, K.E.

1982-01-01

We have completed a design of the Prototype Moving-Ring Reactor. The fusion fuel is confined in current-carrying rings of magnetically-field-reversed plasma (Compact Toroids). The plasma rings, formed by a coaxial plasma gun, undergo adiabatic magnetic compression to ignition temperature while they are being injected into the reactor's burner section. The cylindrical burner chamber is divided into three burn stations. Separator coils and a slight axial guide field gradient are used to shuttle the ignited toroids rapidly from one burn station to the next, pausing for 1/3 of the total burn time at each station. D-T- 3 He ice pellets refuel the rings at a rate which maintains constant radiated power

Proton energy and scattering angle radiographs to improve proton treatment planning : a Monte Carlo study

NARCIS (Netherlands)

Biegun, Aleksandra; Takatsu, Jun; Nakaji, Taku; van Goethem, Marc-Jan; van der Graaf, Emiel; Koffeman, E.; Visser, Jan; Brandenburg, Sijtze

2016-01-01

The novel proton radiography imaging technique has a large potential to be used in direct measurement of the proton energy loss (proton stopping power, PSP) in various tissues in the patient. The uncertainty of PSPs, currently obtained from translation of X-ray Computed Tomography (xCT) images,

Adiabatic compression of ion rings

International Nuclear Information System (INIS)

Larrabee, D.A.; Lovelace, R.V.

1982-01-01

A study has been made of the compression of collisionless ion rings in an increasing external magnetic field, B/sub e/ = zB/sub e/(t), by numerically implementing a previously developed kinetic theory of ring compression. The theory is general in that there is no limitation on the ring geometry or the compression ratio, lambdaequivalentB/sub e/ (final)/B/sub e/ (initial)> or =1. However, the motion of a single particle in an equilibrium is assumed to be completely characterized by its energy H and canonical angular momentum P/sub theta/ with the absence of a third constant of the motion. The present computational work assumes that plasma currents are negligible, as is appropriate for a low-temperature collisional plasma. For a variety of initial ring geometries and initial distribution functions (having a single value of P/sub theta/), it is found that the parameters for ''fat'', small aspect ratio rings follow general scaling laws over a large range of compression ratios, 1 3 : The ring radius varies as lambda/sup -1/2/; the average single particle energy as lambda/sup 0.72/; the root mean square energy spread as lambda/sup 1.1/; and the total current as lambda/sup 0.79/. The field reversal parameter is found to saturate at values typically between 2 and 3. For large compression ratios the current density is found to ''hollow out''. This hollowing tends to improve the interchange stability of an embedded low β plasma. The implications of these scaling laws for fusion reactor systems are discussed

η-meson production in proton-proton collisions at excess energies of 40 and 72 MeV

Science.gov (United States)

Petrén, H.; Bargholtz, Chr.; Bashkanov, M.; Bogoslavsky, D.; Calén, H.; Clement, H.; Demirörs, L.; Ekström, C.; Fransson, K.; Fäldt, G.; Gerén, L.; Höistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, T.; Keleta, S.; Khakimova, O.; Koch, I.; Kren, F.; Kullander, S.; Kupść, A.; Lindberg, K.; Marciniewski, P.; Morosov, B.; Pauly, C.; Petukhov, Y.; Povtorejko, A.; Schönning, K.; Scobel, W.; Skorodko, T.; Stepaniak, J.; Tegnér, P.-E.; Thörngren Engblom, P.; Tikhomirov, V.; Wilkin, C.; Wolke, M.; Zabierowski, J.; Zartova, I.; Złomańczuk, J.

2010-11-01

The production of η mesons in proton-proton collisions has been studied using the WASA detector at the CELSIUS storage ring at excess energies of Q=40 MeV and Q=72 MeV. The η was detected through its 2γ decay in a near-4π electromagnetic calorimeter, whereas the protons were measured by a combination of straw chambers and plastic scintillator planes in the forward hemisphere. About 6.9×104 and 9.3×104 events were found at Q=40 MeV and Q=72 MeV, respectively, with background contributions of less than 5%. A simple parametrization of the production cross section in terms of low partial waves was used to evaluate the acceptance corrections. Strong evidence was found for the influence of higher partial waves. The Dalitz plots show the presence of p waves in both the pp and the η{pp} systems and the angular distributions of the η in the center-of-mass frame suggest the influence of d-wave η mesons.

The cross-section for J/psi production in proton-proton collisions at centre-of-mass energies between 23 and 63 GeV/c

International Nuclear Information System (INIS)

Cobb, J.H.; Iwata, S.; Palmer, R.B.; Rahm, D.C.; Stumer, I.; Fabjan, C.W.; Mannelli, I.; Nakamura, K.; Nappi, A.; Struczinski, W.; Willis, W.J.; Goldberg, M.; Horwitz, N.; Moneti, G.C.; Kourkoumelis, C.; Lankford, A.J.; Rehak, P.

1977-01-01

The cross-section for J/psi production in proton-proton collisions has been measured as a function of centre-of-mass energy at the CERN Intersecting Storage Rings by observing its decay into electron-positron pairs. This cross-section is found to rise by a factor of about six over the full centre-of mass energy range from √s=23 to √s=63 GeV. Electrons resulting from this decay were identified by the use of liquid argon calorimeters and lithium foil transition radiators. Measurements of the energies of the electrons were obtained from the liquid argon calorimeters. (Auth.)

How It's Made - Polarized Proton Beam (444th Brookhaven Lecture)

International Nuclear Information System (INIS)

Zelenski, Anatoli

2008-01-01

Experiments with polarized beams at RHIC will provide fundamental tests of QCD, and the electro-weak interaction reveal the spin structure of the proton. Polarization asymmetries and parity violation are the strong signatures for identification of the fundamental processes, which are otherwise inaccessible. Such experiments require the maximum available luminosity and therefore polarization must be obtained as an extra beam quality without sacrificing intensity. There are proposals to polarize the high-energy proton beam in the storage rings by the Stern-Gerlach effect or spin-filter techniques. But so far, the only practically available option is acceleration of the polarized beam produced in the source and taking care of polarization survival during acceleration and storage. Two major innovations -- the 'Siberian Snake' technique for polarization preservation during acceleration and high current polarized proton sources make spin physics with the high-energy polarized beams feasible. The RHIC is the first high-energy collider, where the 'Siberian Snake' technique allowed of polarized proton beam acceleration up-to 250 GeV energy. The RHIC unique Optically Pumped Polarized Ion Source produces sufficient polarized beam intensity for complete saturation of the RHIC acceptance. This polarization technique is based on spin-transfer collisions between a proton or atomic hydrogen beam of a few keV beam energy and optically pumped alkali metal vapors. From the first proposal and feasibility studies to the operational source this development can be considered as example of successful unification of individual scientists ingenuity, international collaboration and modern technology application for creation of a new polarization technique, which allowed of two-to-three order of magnitude polarized beam intensity increase sufficient for loading the RHIC to its full capacity for polarization studies.

Ray Tracing through the Edge Focusing of Rectangular Benders and an Improved Model for the Los Alamos Proton Storage Ring

Energy Technology Data Exchange (ETDEWEB)

Kolski, Jeffrey S. [Los Alamos National Laboratory; Barlow, David B. [Los Alamos National Laboratory; Macek, Robert J. [Los Alamos National Laboratory; McCrady, Rodney C. [Los Alamos National Laboratory

2011-01-01

Particle ray tracing through simulated 3D magnetic fields was executed to investigate the effective quadrupole strength of the edge focusing of the rectangular bending magnets in the Los Alamos Proton Storage Ring (PSR). The particle rays receive a kick in the edge field of the rectangular dipole. A focal length may be calculated from the particle tracking and related to the fringe field integral (FINT) model parameter. This tech note introduces the baseline lattice model of the PSR and motivates the need for an improvement in the baseline model's vertical tune prediction, which differs from measurement by .05. An improved model of the PSR is created by modifying the fringe field integral parameter to those suggested by the ray tracing investigation. This improved model is then verified against measurement at the nominal PSR operating set point and at set points far away from the nominal operating conditions. Lastly, Linear Optics from Closed Orbits (LOCO) is employed in an orbit response matrix method for model improvement to verify the quadrupole strengths of the improved model.

Preliminary consideration of a double, 480 GeV, fast cycling proton accelerator for production of neutrino beams at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Piekarz, Henryk; Hays, Steven; /Fermilab

2007-03-01

We propose to build the DSF-MR (Double Super-Ferric Main Ring), 480 GeV, fast-cycling (2 second repetition rate) two-beam proton accelerator in the Main Ring tunnel of Fermilab. This accelerator design is based on the super-ferric magnet technology developed for the VLHC, and extended recently to the proposed LER injector for the LHC and fast cycling SF-SPS at CERN. The DSF-MR accelerator system will constitute the final stage of the proton source enabling production of two neutrino beams separated by 2 second time period. These beams will be sent alternately to two detectors located at {approx} 3000 km and {approx} 7500 km away from Fermilab. It is expected that combination of the results from these experiments will offer more than 3 order of magnitudes increased sensitivity for detection and measurement of neutrino oscillations with respect to expectations in any current experiment, and thus may truly enable opening the window into the physics beyond the Standard Model. We examine potential sites for the long baseline neutrino detectors accepting beams from Fermilab. The current injection system consisting of 400 MeV Linac, 8 GeV Booster and the Main Injector can be used to accelerate protons to 45 GeV before transferring them to the DSF-MR. The implementation of the DSF-MR will allow for an 8-fold increase in beam power on the neutrino production target. In this note we outline the proposed new arrangement of the Fermilab accelerator complex. We also briefly describe the DSF-MR magnet design and its power supply, and discuss necessary upgrade of the Tevatron RF system for the use with the DSF-MR accelerator. Finally, we outline the required R&D, cost estimate and possible timeline for the implementation of the DSF-MR accelerator.

Analytical solutions for the invariant spin field for model storage rings

International Nuclear Information System (INIS)

Mane, S.R.

2002-01-01

We present nonperturbative analytical expressions for the invariant spin field for several storage ring models. In particular, we solve the important models of a ring with one Snake and a single resonance driving term, and a ring with two Snakes and a single resonance driving term. We also treat several other models, all of which contain Siberian Snakes. Our solutions contain some novel features, e.g. in some cases the polarization does not point along the direction of the closed-orbit spin quantization axis. We also include vertical resonance driving terms, and consider the contributions of sextupoles and higher order multipoles to the resonance driving terms, and argue that these can play a significant role in some circumstances. We offer some brief remarks on the so-called Snake resonances. We relate our results to observations of higher-order depolarizing spin resonances for polarized proton beams in a real ring, and offer some suggestions as to how our ideas might be verified

Superconducting conversion of the Intersecting storage Rings

International Nuclear Information System (INIS)

1977-01-01

A study is presented of design, performances and cost estimates for superconducting proton storage rings in the existing ISR tunnel at CERN. By using a proven technology for the superconducting magnets an energy of 120 GeV is attainable, which corresponds to a bending field of 5.12 T. Using injection from the PS and stacking at 25 GeV, followed by phase displacement acceleration, luminosities of up to 4.10 33 cm -2 s -1 at 120 GeV are obtained. (Auth.)

Superconducting magnets for high energy storage rings

International Nuclear Information System (INIS)

Sampson, W.B.

1977-01-01

Superconducting dipole and quadrupole magnets were developed for the proton-proton intersecting storage accelerator ISABELLE. Full size prototypes of both kinds of magnets were constructed and successfully tested. The coils are fabricated from a single layer of wide braided superconductor and employ a low temperature iron core. This method of construction leads to two significant performance advantages; little or no training, and the ability of the coil to absorb its total magnetic stored energy without damage. A high pressure (15 atm) helium gas system is used for cooling. Measurements of the random field errors are compared with the expected field distribution. Three magnets (two dipoles and one quadrupole) were assembled into a segment of the accelerator ring structure (half cell). The performance of this magnet array, which is coupled in series both electrically and cryogenically, is also summarized

The longitudinal space charge problem in the high current linear proton accelerators

International Nuclear Information System (INIS)

Lustfeld, H.

1984-01-01

In a linear proton accelerator peak currents of 200 mA lead to high space charge densities and the resultant space charge forces reduce the effective focussing considerably. In particular the longitudinal focussing is affected. A new concept based on linear theory is proposed that restricts the influence of the space charge forces on the longitudinal focussing by increasing a, the mean transverse bunch radius, as a proportional(βγ)sup(3/8). This concept is compared with other concepts for the Alvarez (1 MeV - 100 MeV) and for the high energy part (100 MeV - 1100 MeV) of the SNQ linear accelerator. (orig.)

Final environmental impact statement. Proton--Proton Storage Accelerator Facility (ISABELLE), Brookhaven National Laboratory, Upton, New York

International Nuclear Information System (INIS)

1978-08-01

An Environmental Impact Statement for a proposed research facility (ISABELLE) to be built at Brookhaven National Laboratory (BNL) is presented. It was prepared by the Department of Energy (DOE) following guidelines issued for such analyses. In keeping with DOE policy, this statement presents a concise and issues-oriented analysis of the significant environmental effects associated with the proposed action. ISABELLE is a proposed physics research facility where beams of protons collide providing opportunities to study high energy interactions. The facility would provide two interlaced storage ring proton accelerators, each with an energy up to 400 GeV intersecting in six experimental areas. The rings are contained in a tunnel with a circumference of 3.8 km (2.3 mi). The facility will occupy 250 ha (625 acres) in the NW corner of the existing BNL site. A draft Environmental Impact Statement for this proposed facility was issued for public review and comment by DOE on February 21, 1978. The principal areas of concern expressed were in the areas of radiological impacts and preservation of cultural values. After consideration of these comments, appropriate actions were taken and the text of the statement has been amended to reflect the comments. The text was annotated to indicate the origin of the comment. The Appendices contain a glossary of terms and listings of metric prefixes and conversions and symbols and abbreviations

Properties of the electron cloud in a high-energy positron and electron storage ring

International Nuclear Information System (INIS)

Harkay, K.C.; Rosenberg, R.A.

2003-01-01

Low-energy, background electrons are ubiquitous in high-energy particle accelerators. Under certain conditions, interactions between this electron cloud and the high-energy beam can give rise to numerous effects that can seriously degrade the accelerator performance. These effects range from vacuum degradation to collective beam instabilities and emittance blowup. Although electron-cloud effects were first observed two decades ago in a few proton storage rings, they have in recent years been widely observed and intensely studied in positron and proton rings. Electron-cloud diagnostics developed at the Advanced Photon Source enabled for the first time detailed, direct characterization of the electron-cloud properties in a positron and electron storage ring. From in situ measurements of the electron flux and energy distribution at the vacuum chamber wall, electron-cloud production mechanisms and details of the beam-cloud interaction can be inferred. A significant longitudinal variation of the electron cloud is also observed, due primarily to geometrical details of the vacuum chamber. Such experimental data can be used to provide realistic limits on key input parameters in modeling efforts, leading ultimately to greater confidence in predicting electron-cloud effects in future accelerators.

Saturn’s ring temperatures at equinox

Science.gov (United States)

Spilker, Linda J.; Ferrari, C.; Morishima, R.

2013-10-01

Modeling the thermal emission of Saturn's rings is challenging due to the numerous heating sources as well as the structural properties of the disk and of the particles that are closely related. At equinox, however, the main rings are externally heated by Saturn alone and the problem is somewhat simplified. We test the abilities of our current models to reproduce the temperatures observed with the Cassini CIRS instrument around equinox in August 2009. A simple semi-analytic model which includes mutual shadowing effects can mostly explain the radial profile of the equinox ring temperatures, except the model predicts lower temperatures than those observed for the A ring. The temperature variation at a given saturnocentric radius is primarily caused by observational geometry variations relative to Saturn. The observed temperature increases with decreasing Saturn-ring-observer angle. In addition, we found evidence that the leading hemispheres of particles are warmer than the trailing hemispheres at least for the C ring and probably for the A and B rings as well. This is explained if some fraction of particles has spin rates lower than the synchronous rotation rate as predicted by N-body simulations. The spin model for a monolayer ring (Ferrari, C., Leyrat, C., 2006, Astron. Astrophys. 447, 745-760) can fit the temperature variations with spacecraft longitude observed in the C ring with currently known thermal properties and a mixing of slow and fast rotators. The multilayer model (Morishima, R., Salo, H., Ohtsuki, K., 2009, Icarus 201, 634-654) can reproduce the temperatures of the B and C rings but gives A ring temperatures that are significantly lower than those observed as does the simple semi-analytic model. More advanced models which take into account self-gravity wakes may explain the A ring temperature behavior.

Polarized Proton Collisions at RHIC

CERN Document Server

Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y

2005-01-01

The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

Main Ring bunch spreaders: Past, 1987/1988 fixed target run, and proposed future

International Nuclear Information System (INIS)

Jackson, G.P.

1989-01-01

During the last 1987--1988 fixed target running period beam intensity was limited many times by coherent instabilities in both the Main Ring and in the Tevatron. The intensity thresholds for instabilities are generally inversely proportional to the proton bunch length. Since fixed target operations are insensitive to the longitudinal phase space emittance of the beam, bunch spreaders are employed to increase this emittance, and hence the bunch length. As a result, more beam intensity can be delivered to the fixed target experiments. This paper starts with a short history behind the old Main Ring bunch spreader. After discussing the physics of stimulated emittance growth, the design and performance of the 1987--1988 fixed target run Main Ring bunch spreader is discussed. Finally, designs of improved Main Ring and Tevatron bunch spreaders for the next fixed target run are proposed. 23 figs

The donut and dynamic polarization effects in proton channeling through carbon nanotubes

DEFF Research Database (Denmark)

Borka, D.; Mowbray, Duncan; Miskovic, Z.L.

2010-01-01

We investigate the angular and spatial distributions of protons with an energy of 0.223 MeV after channeling them through an (11, 9) single-wall carbon nanotube of 0.2 mu m length. The proton incident angle is varied between 0 and 10 mrad, being close to the critical angle for channeling. We show...... that, as the proton incident angle increases and approaches the critical angle for channeling, a ring-like structure is developed in the angular distribution-the donut effect. We demonstrate that it is the rainbow effect. If the proton incident angle is between zero and half of the critical angle...... for channeling, the image force affects considerably the number and positions of the maxima of the angular and spatial distributions. However, if the proton incident angle is close to the critical angle for channeling, its influence on the angular and spatial distributions is considerably decreased. We...