Search

Experiments on the beam dynamics and on the internal cooling of ions stored in a linear electrostatic ion beam trap operated at < 15K are reported. The extremely low density of residual gas and resulting long storage times afforded by the cold environment have enabled observation of ion bunches maintained by a self-synchronizing mechanism for up to 12 s. The experiment is compared with a model of the bunch decoherence process to illuminate the mechanisms behind both the long persistence of the bunches and their eventual decay into a continuous beam. In a different experiment the change in the vibrational temperature of stored Al4- and Al5- cluster anions via radiative cooling was monitored by using the laser-induced detachment of electrons as a diagnostic. [ABSTRACT FROM AUTHOR]

The brief achievements of HIRFL-CSR commissioning and the achieved parameters of its coolers were presented. With the help of electron cooling code, the cooling time of ion beam were extensive simulated in various parameters of the ion beam in the HIRFL-CSR electron cooling storage rings respectively, such as ion beam energy, initial transverse emittance, and momentum spread. The influence of the machine lattice parameters-betatron function, and dispersion function on the cooling time was investigated. The parameters of electron beam and cooling devices were taken into account, such as effective cooling length, magnetic field strength and its parallelism in cooling section, electron beam size and density. As a result, the lattice parameters of HIRFL-CSR were optimal for electron cooling, and the parameters of electron beam can be optimized according to the parameters of heavy ion beam. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The 8.9-GeV/c Recycler antiproton storage ring is equipped with both stochastic and electron cooling systems. These cooling systems are designed to assist accumulation of antiprotons for the Tevatron collider operations. In this paper we report on an experimental demonstration of electron cooling of high-energy antiprotons. At the time of writing this report, the Recycler electron cooling system is routinely used in collider operations. It has helped to set recent peak luminosity records. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The design of an electron cooler must take into account both electron beam dynamics issues as well as the electron cooling physics. Research towards high-energy electron cooling of RHIC is in its 3rd year at Brookhaven National Laboratory. The luminosity upgrade of RHIC calls for electron cooling of various stored ion beams, such as 100 GeV/A gold ions at collision energies. The necessary electron energy of 54 MeV is clearly out of reach for DC accelerator system of any kind. The high energy also necessitates a bunched beam, with a high electron bunch charge, low emittance and small energy spread. The Collider-Accelerator Department adopted the Energy Recovery Linac (ERL) for generating the high-current, high-energy and high-quality electron beam. The RHIC electron cooler ERL will use four Superconducting RF (SRF) 5-cell cavities, designed to operate at ampere-class average currents with high bunch charges. The electron source will be a superconducting, 705.75 MHz laser-photocathode RF gun, followed up by a superconducting Energy Recovery Linac (ERL). An R&D ERL is under construction to demonstrate the ERL at the unprecedented average current of 0.5 amperes. Beam dynamics performance and luminosity enhancement are described for the case of magnetized and non-magnetized electron cooling of RHIC. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Antiproton Decelerator (AD) at CERN operates for physics since 1999. The 3.5 GeV/c antiprotons produced in the target by a 26 GeV/c proton beam coming from CERN PS. Since the experiments need a low energy antiprotons, beam is decelerated in the AD down to an extraction momentum of 100 MeV/c. Due to significant emittance blow up during deceleration, as well as tight requirements from experiments on extracted beam sizes, efficient compression of beam phase space is indispensable. Two cooling systems, stochastic and electron are used in AD. The progress in machine performance is reviewed, along with plans for the future. Special emphasis is given to the proposed new extra low energy antiproton ring (ELENA) for deceleration of antiproton beam further down to an energy of 100 keV (momentum 13.7 MeV/c), which would allow much higher antiproton capture rate with significantly higher beam density. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

An antiproton-ion collider (AIC), with extensive using of electron cooling, is proposed to determine rms radii for protons and neutrons in unstable and short lived nuclei by means of antiproton absorption at medium energies. The experiment makes use of the electron-ion collider complex with appropriate modifications of the electron ring to store, cool and collide antiprotons of 30 MeV energy with 740 MeV/unit ions in the NESR. Antiprotons are collected, cooled, decelerated up to 30 MeV and transferred to the electron storage ring. The radioactive nuclei beams are transferred to the CR and cooled at 740A MeV and transported via the RESR to NESR, in which especially short lived nuclei are accumulated continuously to increase the luminosity. Luminosities of about 1023 cm-2s-1 may be reached with 106 ions accumulated in the NESR in coasting mode of operation, used for Schottky spectroscopy of the fragments. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Electron cooling of 8.9 GeV/c antiprotons in the Recycler ring (Fermilab) requires high current and good quality of the DC electron beam. Electron trajectories of ∼0.2 A or higher DC electron beam have to be parallel in the cooling section, within ∼ 0.2 mrad, making the beam envelope cylindrical. These requirements yielded a specific scheme of the electron transport from a gun to the cooling section, with electrostatic acceleration and deceleration in the Pelletron. Recuperation of the DC beam limits beam losses at as tiny level as ∼0.001%, setting strict requirements on the return electron line to the Pelletron and a collector. To smooth the beam envelope in the cooling section, it has to be linear and known at the transport start. Also, strength of the relevant optic elements has to be measured with good accuracy. Beam-based optic measurements are being carried out and analysed to get this information. They include beam simulations in the Pelletron, differential optic (beam response) measurements and simulation, beam profile measurements with optical transition radiation, envelope measuremen6ts and analysis with orifice scrapers. Current results for the first half-year of commissioning are presented. Although electron cooling is already routinely used for pbar stacking, its efficiency is expected to be improved. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Electron cooling of the 8.9 GeV/c antiprotons in the Recycler ring requires high-quality dc electron beam with the current of several hundred mA and the kinetic energy of 4.3 MeV. That high electron current is attained through beam recirculation (charge recovery). The primary current path is from the magnetized cathode at high voltage terminal to the ground, where the electron beam interacts with the antiproton beam and cooling takes place, and then to the collector in the terminal. The energy distribution function of the electron beam at the collector determines the required collector energy acceptance. Multiple and single intra-beam scattering as well as the dissipation of density micro-fluctuations during the beam transport are studied as factors forming a core and tails of the electron energy distribution. For parameters of the Fermilab electron cooler, the single intra-beam scattering (Touschek effect) is found to be of the most importance. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The design of future high energy coolers relies heavily on extending the results of cooling force measurements into new regimes by using simulation codes. In order to carefully benchmark these codes we have accurately measured the longitudinal friction force in CELSIUS by recording the phase shift between the beam and the RF voltage while varying the RF frequency. Moreover, parameter dependencies on the electron current, solenoid magnetic field and magnetic field alignment were carried out. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

High-energy electron cooling, presently considered as essential tool for several applications in high-energy and nuclear physics, requires accurate description of the friction force. A series of measurements were performed at CELSIUS with the goal to provide accurate data needed for the benchmarking of theories and simulations. Some results of accurate comparison of experimental data with the friction force formulas are presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The recent demonstration of electron cooling of antiprotons in the Recycler ring required a stable 4.3 MeV electron beam with a DC current of hundreds of mA and an angular spread in the cooling section of a fraction of a mrad. This paper describes the achieved parameters of the Fermilab cooler’s electron beam and details of operation. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Results of experimental studies of the electron cooling of a proton beam at COSY (Juelich, Germany) are presented. Intensity of the proton beam is limited by two general effects: particle loss directly after the injection and development of instability in a deep cooled ion beam. Results of the instability investigations performed at COSY during last years are presented in this report in comparison with previous results from HIMAC (Chiba, Japan) CELSIUS (Uppsala, Sweden) and LEAR (CERN). Methods of the instability suppression, which allow increasing the cooled beam intensity, are described. This work is supported by RFBR grant [sharp/mesh/hash_synonym] 05-02-16320 and INTAS grant [sharp/mesh/hash_synonym]03-54-5584. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The maximum electron energy of the HESR electron cooling system has been decided to be 4.5 MeV, with a possible future upgrade to 8 MeV. Calculations with BETACOOL have been carried out; these include effects of imperfections of the electron beam as well as the internal hydrogen pellet target and intra-beam scattering. Design work is going on. This makes use of the experience gained at the FNAL Recycler and aims to result in a practical solution, which includes considerations for robustness as well as ease of assembly, bake-out, and to make use of proven solutions as much as possible. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The design, construction and installation of a 2 MeV electron cooling system for COSY is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the design of the 2 MeV electron cooler for COSY is intended to test some new features of the high energy electron cooler for HESR at GSI. The design of the 2 MeV electron cooler will be accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. Starting with the boundary conditions of the existing electron cooler at COSY the requirements and a first general scheme of the 2 MeV electron cooler are described. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The subject of the report is the problem of the technical feasibility of fast electron cooling in the energy range between 0.8 and 14.5 GeV. It is very useful for one of the major objectives of the GSI and COSY future plans. For the realization of the cooler device BINP team proposes the design that is like the conventional and elaborated for the low energy cooling (up to 300 keV). The main features of this design are the accelerating tube immersed in the magnetic field along the whole length and the strong magnetic field in the cooling section. The physics of electron cooling is based on the idea of the fast magnetized cooling. The cooling force at strong magnet field was measured at many experiments and can be surely estimated. The magnetized cooling rate enables to obtain the required beam parameters, eliminate the beam heating due to intrabeam scattering, fluctuations of ionization energy losses and multiple scattering in the internal target. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

A proposed luminosity upgrade to the Relativistic Heavy Ion Collider (RHIC) includes a novel electron cooling section, which would use ∼55 MeV electrons to cool fully-ionized 100 GeV/nucleon gold ions. We consider the dynamical friction force exerted on individual ions due to a relevant electron distribution. The electrons may be focussed by a strong solenoid field, with sensitive dependence on errors, or by a wiggler field. In the rest frame of the relativistic co-propagating electron and ion beams, where the friction force can be simulated for nonrelativistic motion and electrostatic fields, the Lorentz transform of these spatially-varying magnetic fields includes strong, rapidly-varying electric fields. Previous friction force simulations for unmagnetized electrons or error-free solenoids used a 4th-order Hermite algorithm, which is not well-suited for the inclusion of strong, rapidly-varying external fields. We present here a new algorithm for friction force simulations, using an exact two-body collision model to accurately resolve close interactions between electron/ion pairs. This field-free binary-collision model is combined with a modified Boris push, using an operator-splitting approach, to include the effects of external fields. The algorithm has been implemented in the VORPAL code and successfully benchmarked. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

HIRFL-CSR, a new ion accelerator complex, is under construction at IMP, Lanzhou, China. It is equipped with two electron cooling devices. This article describes the commissioning of cooler at electron energy 300 keV. The cooler is one of the new coolers with some unique manufactured in BINP, Russia. It has a new electron gun producing a hollow electron beam, electrostatic bending and a new structure of solenoid coils at the cooling section. The test results of cooler obtained in Novosibirskand Lanzhou are reported. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

High-energy electron cooling for RHIC presents many unique features and challenges. An accurate estimate of the cooling times requires detailed simulation of the electron cooling process. The first step towards such calculations is to have an accurate description of the cooling force. Numerical simulations are being used to explore various features of the friction force which appear due to several effects, including the anisotropy of the electron distribution in velocity space and the effect of a strong solenoidal magnetic field. These aspects are being studied in detail using the VORPAL code, which explicitly resolves close binary collisions. Results are compared with available asymptotic and empirical formulas and also, using the BETACOOL code, with direct numerical integration of less approximate expressions over the specified electron distribution function. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Cryogenic Storage Ring (CSR) is currently under construction at MPI-K in Heidelberg. The CSR is an electrostatic ring with a total circumference of about 34 m, straight section length of 2.5 m and will store ions in the 20 ∼ 300 keV energy range (E/Q). The cryogenic system in the CSR is expected to cool the inner vacuum chamber down to 2 K. The CSR will be equipped with an electron cooler which has also to serve as an electron target for high resolution recombination experiments. In this paper we present the results of numerical investigations of the CSR lattice with finite element calculations of the deflection and focusing elements of the ring. We also present a layout of the CSR electron cooler which will have to operate in low energy mode to cool 20 keV protons in the CSR, as well as numerical estimations of the cooling times to be expected with this device. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

An important aspect of the cooler operation is the collector efficiency. The low loss current improves the vacuum condition, the radiation condition and makes the easy design of the power supply system. This article deals with the reuse of collector at the electrostatic bending in the toroidal section. It’s possible to compensate the centrifugal force for the secondary electrons by the electric field because the effect of both forces is independent from the direction of the electron longitudinal velocity. As result the secondary electrons may return into the collector after reflection from the gun. Nonzero loss current is defined mainly by the energy spectrum of the secondary electrons. The review of the experimental data for the different cooler is described in this article. The range of the electron energy is 2 – 300 keV. Some physical model is proposed for the experiment explanations. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Experiments of electron cooling have been done with the HIMAC synchrotron in NIRS. Limitation on cooled beam-sizes in longitudianl and transverse spaces were measured. The effect of space-charge field and intra-beam scattering are investigated. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Description of equipment developed at BINP SB RAS for precision solenoid magnetic field measurement is presented in the paper. Transversal field components are measured by small compass-based sensor during its motion along the field line. The sensor sensitivity is a few tenth parts of mG and is limited in this range by external noise sources only. Scope of the device application is illustrated by results obtained at BINP during tests of cooling solenoids for electron coolers built at the Institute recently. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

New electron cooling device was constructed for LEIR accumulator ring according to ILHC project at CERN. The cooler was designed, manufactured and completely tested with electron beam at BINP (Novosibirsk, Russia). Special features of the device and the results obtained are presented in the paper. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

A wide usage of carbon ions for cancer therapy is limited mostly due to technical difficulties, resulting in higher cost. This cost problem can be solved by our CBS (Cold Beam Synchrotron) proposal. In this paper a conceptual design of the facility for the carbon beam cancer therapy using a high precise active beam scanning system of synchronizing with respiration. The main feature of the CBS facility is an application of electron cooling device. The use of cold ion beam allows to decrease the aperture of synchrotron and components of high energy beam transport lines, significantly. The precise ion beam energy variation and two unique schemes of beam extraction (“pellet” extraction and extraction on recombination) enclose the list of possibilities appearing with EC applying. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide maximum cooling of the antiprotons in the Recycler. A measurement system was developed using movable apertures and steering bumps to measure the beam size in a 20m long, nearly continuous, solenoid. This paper will focus on results of these measurements of the beam size and the difficulties in making those measurements. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Cooling of 8.9-GeV/c antiprotons in the Recycler Electron Cooler requires a round 4.34-MeV electron beam with a small angular spread propagating through a 20-m long cooling section. To confine the electron beam tightly and to keep its total transverse angles below 0.2 mrad the cooling section is immersed in a solenoidal field of 50–200 G. The field was measured with a compass-based sensor (transversal) and a hall-probe (longitudinal) after installation of the solenoids into the Recycler tunnel. For the field strength of 105 G, the transverse field components were compensated to the level that provided corresponding dipole beam oscillations below 0.1 mrad, which in turn allowed the first cooling of antiprotons in the GeV energy range. This paper discusses the field measurements and compensation scheme including the results of dipole oscillation measurements. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

For a theoretical description of electron cooling of ions or antiprotons in traps we have investigated the energy loss and cooling force in a strongly magnetized electron plasma employing both perturbation approaches and more complete numerical simulations. Some characteristic features for cooling under conditions prevailing in Penning traps are presented. One particular feature is, that the energy loss in strongly magnetized electrons, which tend to move along the field lines like beads on a wire, strongly depends on the sign of the interaction. The energy loss can be significantly larger for antiprotons than for protons. Special attention is paid to the cooling of highly charged ions, here bare Uranium, in HITRAP. The time evolution of the energy distribution of the trapped ions is studied within a simplified model which takes into account the related heating of the electrons. The feedback of this heating on the energy loss results in an intricate dependency of the cooling times on the density of the electrons and the ratio of the number of ions to the number of electrons in the trap. From this analysis we find that cooling times less than about a second are feasible for electron cooling of bare Uranium in HITRAP. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Fermilab Electron Cooling Project requires low effective anglular spread of electrons in the cooling section. One of the main components of the effective electron angles is an angle of electron beam centroid with respect to antiproton beam. This angle is caused by the poor quality of magnetic field in the 20 m long cooling section solenoid and by the mismatch of the beam centroid to the entrance of the cooling section. This paper focuses on the beam-based procedure of the alignment of the cooling section field and beam centroid matching. The discussed procedure allows to suppress the beam centroid angles below the critical value of 0.1 mrad. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Fermilab’s 4.3 MeV electron cooler is based on an electrostatic accelerator, which generates a DC electron beam in an energy recovery mode. Effective cooling of the antiprotons in the Recycler requires that the beam remains stable for hours. While short beam interruptions do not deteriorate the performance of the Recycler ring, the beam may provoke full discharges in the accelerator, which significantly affect the duty factor of the machine as well as the reliability of various components. Although cooling of 8 GeV antiprotons has been successfully achieved, full discharges still occur in the current setup. The paper describes factors leading to full discharges and ways to prevent them. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The ultra-low energy storage ring (USR) will be a multi-purpose facility providing electron-cooled antiprotons in the energy range between 20 keV and 300 keV for both in-ring experiments and effective injection into traps. The low beam energies and high beam quality to be provided by this accelerator will enable new studies of antimatter/matter interactions using in-ring experiments with an internal gas jet target as well as particle traps, which can be efficiently filled using the decelerated and cooled antiproton beam. High luminosity, low emittance and low momentum spread are some of the main characteristics of the electron-cooled antiproton beam that shall be achieved and that the various experiments may take advantage of. The layout of an electron cooler at such low energies is a great challenge and questions like the competition between multiple scattering and electron cooling, the needed cooling power with an installed internal target or the influence of the electron temperature on the cooling time have to be addressed for the first time. In this contribution, the layout of the USR is summarized and results from simulations with the BETACOOL code are presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

For the production of ultraslow antiproton beams, decelerated antiprotons were captured in an electro-magnetic trap and cooled by collisions with preloaded electrons. This electron cooling feature was non-destructively monitored by measurement of electrostatic oscillations of the electron plasma. The radial distribution of the plasma was controlled for efficient cooling and extraction by utilizing rotating wall field technique. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

A decelerator will be installed at GSI in order to provide and study bare heavy nuclei or heavy nuclei with only few electrons at very low energies or even at rest. Highly-charged ions will be produced by stripping at relativistic energies. After electron cooling and deceleration in the Experimental Storage Ring the ions are ejected out of the storage ring at 4 MeV/u and further decelerated in a combination of an IH and RFQ structure. Finally, they are injected into a Penning trap where the ions are cooled to 4 K. From here, the ions can be transfered in a quasi dc or in a pulsed mode to different experimental setups. This article describes the technical concepts of this project as well as planned key experiments. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The ESR storage ring is equipped with stochastic and electron cooling. Electron cooling is the standard method for most internal experiments with stored heavy ion or rare isotope beams covering a wide energy range. Stochastic cooling is mainly used as a pre-cooling method for hot beams. The combination of both methods allows a considerable reduction of the total cooling time, which is particularly important for experiments with short-lived radioactive ions. At low beam intensity electron cooling results in extremely cold beams which show clear evidence for ordering in a linear string-like structure. A special ion optical mode of the ESR reduces the transition energy to γt = 1.37, thus the behavior of cooled beams above transition energy can be studied. Laser cooling of a C3+ beam of velocity β = 0.47 is being developed employing electron cooling as a pre-cooling method. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Fermilab is developing a high-energy electron cooling system to cool 8.9-GeV/c antiprotons in the Recycler ring. Cooling of antiprotons requires a round electron beam with a small angular spread propagating through a 20-m long cooling section with a kinetic energy of 4.3 MeV. To confine the electron beam tightly and to keep its transverse angles below 0.1 mrad, the cooling section will be immersed into a solenoidal field of 50–150 G. This paper describes the technique of measuring and adjusting the magnetic field quality in the cooling section and presents preliminary results of beam quality measurements in the cooler prototype. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Production target design for the Muon-Electron Conversion Experiment has undergone significant evolution recently. Limited progress in producing a suitable radiation-cooled target has spurred interest in a water-cooling system with drastically lower operating temperatures. This system results in less than about five percent reduction in stopped muon yield compared to a similar radiation cooled unit. The theoretical and experimental research surrounding target design is discussed. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Electron cooling is used for damping both single particle and coherent oscillations of ion beams. The extremely high phase space density of the cooled ion beam can become a source of stability problems ("electron heating"). For storage rings such as CELSIUS, COSY and the Indiana Cooler, this is a serious problem that limits the use of the electron cooling in physical experiments. Proper design of the electron cooler can improve the stability of the cooled ion beam. [ABSTRACT FROM AUTHOR]

The method of electron cooling uses an energy exchange between ions and electrons, both moving with the same average velocity in a special section of the ion ring [1]. [ABSTRACT FROM AUTHOR]

The article presents a working group's summary report on the proposed 2MV electron cooler for the COSY ring. Some of the topics discussed by the group were relevance of magnetic cooling, technical differences between magnetized and non-magnetized electron cooling and importance of interaction studies between ion beams and high density targets in the presence of electron cooling.