COOL2017 - Classification: Electron Cooling

Paper	Title	Page
MOA12	The Muon Ionization Cooling Experiment	1
	M.A. Uchida Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	The Muon Ionization Cooling Experiment (MICE) is designed to demonstrate a measurable reduction in muon beam emittance due to ionization cooling. This demonstration will be an important step in establishing the feasibility of muon accelerators for particle physics. The emittance of a variety of muon beams is measured before and after a "cooling cell", allowing the change in the phase-space distribution due to the presence of an absorber to be measured. Two solenoid spectrometers are instrumented with high-precision scintillating-fibre tracking detectors (Trackers) before and after the cooling cell which measure the normalized emittance reduction. Data has been taken since the end of 2015 to study several beams of varying momentum and input emittance as well as three absorber materials in the cooling cell, over a range of optics. The experiment and an overview of the analyses are described here.
	Slides MOA12 [23.988 MB]
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TUM11	Low Energy Electron Cooler for the NICA Booster	22
	A.V. Bubley, M.I. Bryzgunov, V.A. Chekavinskiy, A.D. Goncharov, K. Gorchakov, I.A. Gusev, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.V. Senkov BINP SB RAS, Novosibirsk, Russia A.V. Smirnov JINR, Dubna, Moscow Region, Russia
	The low energy electron cooler for the NICA booster has recently been installed at the booster ring of the NICA facility. The article describes results of various measurements obtained during its commissioning. Also some details of design and construction of the cooler are discussed.
	Slides TUM11 [3.933 MB]
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TUM13	Electron Cooling at COSY - Status and Perspectives
	V. Kamerdzhiev, A.J. Halama FZJ, Jülich, Germany M.I. Bryzgunov, V.V. Parkhomchuk, V.B. Reva BINP SB RAS, Novosibirsk, Russia T. Katayama Nihon University, Narashino, Chiba, Japan
	COSY, a COoler SYnchrotron and storage ring has been initially equipped with a low energy electron cooler. It was mainly used to improve the quality of the beams extracted to fixed-target experiments, to enable transverse stacking of polarized beams to be used with targets in the ring, and to improve the beam lifetime for internal experiments. In 2013 a high-energy e cooler covering the entire energy range of COSY was added. Since then high-energy e cooling has been demonstrated and dedicated cooling beam studies with dc and bunched proton beam have been carried out. Furthermore, the cooling process in presence of an internal cluster jet target continuously affecting the circulating beam was studied. We review the status of electron-cooling activities at COSY, present the latest experimental results, discuss problems encountered and possible cures, and provide insights into the activities envisaged for the next year.
	Slides TUM13 [5.526 MB]
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TUM21	High Voltage Cooler NICA Status and Ideas	25
	V.B. Reva, M.I. Bryzgunov, A.V. Bubley, A.D. Goncharov, N.S. Kremnev, V.M. Panasyuk, V.V. Parkhomchuk, V.A. Polukhin, A.A. Putmakov BINP SB RAS, Novosibirsk, Russia
	The new accelerator complex NICA is designed at the Joint Institute for Nuclear Research (JINR, Dubna, Russia) to do experiment with ion-ion and ion-proton collision in the range energy 1-4.5 GeV/u. The planned luminosity in these experiments is 10²⁷cm^-2c{-1}. This value can be obtained with help of very short bunches with small transverse size. This beam quality can be realized with electron and stochastic cooling at energy of the physics experiment. The subject of the report is the problem of the technical feasibility of fast electron cooling for collider in the energy range between 0.2 and 2.5 MeV. For the realization of the cooler device BINP team proposes the design that is like to COSY cooler. 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 when the ion interacts with Larmour circle and the cooling decrements are improved significantly. The cooling force at strong magnet field was measured at many experiments and can be surely estimated.
	Slides TUM21 [50.456 MB]
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TUM22	Model Development for the Automated Setup of the 2 MeV Electron Cooler Transport Channel	28
	A.J. Halama, V. Kamerdzhiev FZJ, Jülich, Germany
	The 2 MeV electron cooler allows for cooling the proton and deuteron beams in the entire energy range of COSY and thereby study magnetized high energy electron cooling for the HESR and NICA. Manual electron beam adjustment in the high energy, high current regime proves a cumbersome and time consuming task. Special difficulties are presented by the particular geometry of the e-beam transport channel, limited beam diagnostics and general technical limitations. A model has been developed to track electrons through the transport channel of the cooler. This allows the offline study of response schemes around any particular setting of the cooler. It is envisaged to control linear, dipole and quadrupole behavior of the e-beam. Application of the model will result in optimized e-beam transport settings for a lossless and cool beam transport. This will improve cooling and recuperation efficiency and allow quick adjustment of the e-beam to the various operational modes of the machine. A good relative agreement of the model and the cooler could be shown. Main focus lies now in overhauling the software and finding suitable initial conditions to improve the agreement to an absolute degree.
	Slides TUM22 [3.784 MB]
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TUM23	Status of the Turbine Concept for Relativistic Electron Coolers
	K. Aulenbacher IKP, Mainz, Germany
	A turbine driven high voltage section for manetized d.c. electron coolers may offer considerable advantages. This project is pursued in collaboration of BINP and Helmholtzinstitut Mainz. A 600kV prototype has seen first tests and will be installed in a pressurized tank at HIM in 2018. An outlook to further developments will be given.
	Slides TUM23 [1.057 MB]
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TUP07	Secondary Electron and Photon Measurements at the HIM Electron Cooler Test Set-Up
	Th. Beiser IKP, Mainz, Germany K. Aulenbacher, M.W. Bruker, T. Weilbach HIM, Mainz, Germany
	A low-energy test set-up for the measurement and optimisation of secondary electron currents from the collector in electron coolers is presented. A variable-field Wien filter and current-measuring aperture plates grant insight into the trajectory and energy distribution of the secondary particles. Photons emitted by residual gas ions trapped inside the electromagnetic potential of the electron beam can be used to measure the location of the beam. The exact composition of those ions, the optical spectrum of said photons, and the possibility of related beam diagnostics is a subject of ongoing research.
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TUP08	Preliminary Design of Electron Target for SRing at HIAF	40
	J. Li, Z. Huang, L.J. Mao, M.T. Tang, S. X. Wang, J.C. Yang, X.D. Yang, H. Zhao, L.X. Zhao IMP/CAS, Lanzhou, People's Republic of China
	A 13 Tm multifunction storage ring dedicated to nucleon and atomic experiment research - the SRing (Spectrometry Ring) is a significant part of the new heavy-ion research complex - HIAF (High Intensity heavy ion Accelerator Facility). In additional to an electron cooler and a gas internal target planned at the SRing, a beam of low temperature electron is also required to collide with the storage beam and to cool the decelerated ion beam at low energy. A magnetic adiabatic expansion is proposed to attain a low temperature by applying a 1.2 T longitudinal magnetic field upon the thermionic cathode at the electron gun. In this paper, preliminary design of the electron target is introduced.
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TUP09	Project of High-Voltage System with Fast Changing Potential for DR Experiment	44
	V.B. Reva, A.P. Denisov, V.V. Parkhomchuk, A.A. Putmakov, D.N. Skorobogatov BINP SB RAS, Novosibirsk, Russia J. Li, X. Ma, L.J. Mao IMP/CAS, Lanzhou, People's Republic of China
	Funding: The reported study was partially funded by RFBR 16-52-53016. A storage ring equipped with an electron cooler is an ideal platform for dielectronic recombination (DR)experiments. In order to fulfill the requirement of DR measurements the system of the precision control of the relative energy between the ion beam and the electron beam should be installed in the electron cooler device. This report describes the project of such system that is designed with section approach like COSY electron cooler. Each section consist of the section of cascade transformer and two power supplies for low and fast detuning of potential of high-voltage terminal. This project can be used in CSRe and future HIAF storage rings.
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TUP10	Electron Cooling Simulation and Benchmarks
	A. Latina, N. Biancacci CERN, Geneva, Switzerland
	Electron Cooling is a method of damping betratron oscillations of heavy particles, like protons, antiprotons, and ions, through the interaction with cold electrons at small relative velocity. A detailed simulation of the Electron Cooling process has been created using a hybrid kinetic model, where the full 6d phase space of a multi-particle beam is immersed in a fluid plasma of electrons. This simulation has been implemented in the tracking code RF-Track, with the aim of exploring the performance of electron coolers in presence of realistic imperfections. Simulations results, and benchmarks against experimental data measured at CERN at LEIR, are presented and discussed in this poster.
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TUP11	The Interaction Between Electrons and Ions in Comoving and Static Electron Columns	47
	V.A. Britten, M. Droba, O. Meusel, H. Podlech, A. Schempp, K. Schulte IAP, Frankfurt am Main, Germany
	The interaction between electrons and positive ion beams and its application in accelerator physics are investigated. A space charge lens named Gabor lens was developed which confines electrons in a static column by external fields. The confined electrons are used for focusing and may support space charge compensation. In this structure the relative velocity between the ions and the electrons is maximal and corresponds to the beam velocity. An electron lens as at the Tevatron* is operated with a lower relative velocity in order to compensate the beam, to clean the beam abort gap or to excite the beam for beam dynamics measurements. In comparison electron cooling needs the same velocity of the ion and the electron beam. The following study contains the superposition of electric and magnetic self-fields and their impact on the density distribution of the ion beam and of the electron beam. Recombinations and ionisations are neglected. This is the beginning of an interface between these topics to find differences and similarities of the interaction between ions and electrons with different relative velocities. This may open up opportunities e.g. for the diagnostics of particle beams. * Shiltsev, Vladimir, et al. "Tevatron electron lenses: Design and operation." Physical Review Special Topics-Accelerators and Beams 11.10 (2008): 103501.
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TUP12	Simulation of Low Enery Ion Beam Cooling With Pulsed Electron Beam on CSRm	50
	H. Zhao, J. Li, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang IMP/CAS, Lanzhou, People's Republic of China
	The pulsed electron beam can be applied to high ener-gy beam cooling and the researches of ion-electron inter-action in the future. In this paper, we studied the pulsed e-beam cooling effects on coasting and bunched ion beam by simulation code which is based on the theory of elec-tron cooling, IBS and space charge effect etc. In the simu-lation, a rectangular distribution of electron beam was applied to 7 MeV/u 12C⁶⁺ ion beam on CSRm. It is found that the coasting ion beam was bunched by the pulsed e-beam and the rising and falling region of electron beam current play an important role for the bunching effect, and similar phenomenon was found for the bunched ion beam. In addition, the analyses of these phenomena in simulation were discussed.
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TUP13	Calculations of the Gun and Collector for Electron Cooling Systems of HIAF	54
	M.T. Tang, J. Li, H.J. Lu, X.M. Ma, L.J. Mao, T.L. Yan, X.D. Yang, H. Zhao, L.X. Zhao IMP/CAS, Lanzhou, People's Republic of China A.V. Ivanov BINP SB RAS, Novosibirsk, Russia
	Two electron coolers are designed for the new project HIAF, one cooler with the highest energy 50keV is for the booster ring (BRing) to decreasing the transverse emittance of injected beams and another one with the highest energy 450keV is for the high precision Spec-trometer Ring (SRing). In this paper the results of the gun and collector simulation for these two electron coolers are presented. After optimization, the gun can produce 2A profile variable electron beam. The one time collecting efficiency is higher than 99.99%. The results of electron motions in toroid calculated by a numerical method are also summarized in this paper.
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TUP14	Investigation on the Suppression of Intrabeam Scattering in the High Intensity Heavy Ion Beam with the help of Longitudinal Multi-bunch Chain of Electron	58
	X.D. Yang, J. Li, X.M. Ma, L.J. Mao, M.T. Tang, T.L. Yan, H. Zhao IMP/CAS, Lanzhou, People's Republic of China
	Intrabeam scattering is the main reason of degradation of the beam brightness and shortening of brightness lifetime in the collider, light source and storage ring. The intrabeam scattering presents dissimilar influence in the different facilities. Electron cooling was chose to suppress the effect of intrabeam scattering, another unexpected effect happened during the cooling. The distribution of ion beam quickly deviates from the initial Gaussian type, form a denser core and long tail. The ions standing in the tail of beam will loss soon due to large amplitude. This solution will focus on the investigation on the suppression of intrabeam scattering in the high intensity heavy ion beam in the storage ring with the help of longitudinally modulated electron beam. The stronger cooling was expected in the tail of ion beam and the weaker cooling was performed in the tail of ion beam. The particle in the outside will experience stronger cooling and will be driven back into the centre of ion beam. The ion loss will be decreased and the lifetime will be increased. The intensity of ion beam in the storage ring will be kept and maintain for long time.
	Poster TUP14 [4.160 MB]
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TUP15	Experimental Demonstration of Electron Cooling with Bunched Electron Beam	61
	L.J. Mao, J. Li, X.M. Ma, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. Spata, H. Wang, S. Wang, H. Zhang, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: This work was supported by the Hundred Talents Project of the Chinese Academy of Sciences and National Natural Science Foundation of China (Nos. 11575264, 11475235, 11375245) Electron cooling at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler was modified by pulsing the grid voltage, by which a 0.5-3.5 us of electron bunch length with a repetition frequency of less than 250 kHz was obtained. The first experiment demonstrated cooling coasting and bunched ion beam by a bunched electron beam was carried out at the storage ring CSRm at IMP. A preliminary data analysis has indicted the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam. A longitudinal grouping effect of coasting ion beam by the electron bunch has also observed. In this paper, we will present the experiment result and its preliminary comparison to the simulation modeling.
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WEM11	Status of Bunched Beam Electron Cooler LEReC
	A.V. Fedotov BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the U.S. Department of Energy. The Low Energy RHIC electron Cooler (LEReC) system is presently under construction and commissioning at BNL. Although required energies of electron beam (few MeV) are not very high, an approach based on RF acceleration of electron beams was chosen. Required electron beam and its acceleration will be provided by the photoemission electron gun and the RF linear accelerator. As a result, cooling will be accomplished by using bunched electron beams produced by high-brightness high-current electron linear accelerator. Here, we describe design aspects and challenges of such an approach, as well as summarize status of the LEReC project. First commissioning results of the LEReC injector are also presented. on behalf of the LEReC team.
	Slides WEM11 [4.363 MB]
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WEM12	Development of a Bunched Beam Electron Cooler Based on ERL and Circulator Ring Technology for the Jefferson Lab Electron-Ion Collider	72
	S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, A. Hutton, R. Li, R.A. Rimmer, Y. Roblin, C. Tennant, H. Wang, H. Zhang, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Jefferson Lab is in the process of designing an electron ion collider with unprecedented luminosity at a 45 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires the novel use of bunched-beam cooling. There are two designs for such a bunched beam cooler. The first uses a conventional Energy Recovery Linac (ERL) with a magnetized beam while the second uses a circulating ring to enhance both the peak and average current experienced by the ion beam. This presentation will describe the design of both the Circulator Cooling Ring (CCR) design and that of the backup option using the stand-alone ERL operated at lower charge but higher repetition rate than the ERL injector required by the CCR-based design.
	Slides WEM12 [5.124 MB]
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WEM13	Electron Cooling of Bunched Ion Beams and Recent Results at the Heidelberg Cryogenic Storage Ring (CSR)
	P. Wilhelm MPI-K, Heidelberg, Germany
	The cryogenic storage ring CSR is an electrostatic machine of 35 m circumference for positive and negative ions at up to 300 keV kinetic energy per charge. Vacuum chambers and ion optics are cooled to well below 10 K by a closed-cycle He system. Rest gas densities down to a room-temperature equivalent pressure of <10^-14 mbar and 1/e ion-beam lifetimes up to ~45 min were observed. With rotationally cold diatomic ions, photodissociation Feshbach resonances of CH⁺ (J=0,1,2) were reported. By time-dependent laser photodetachment, free-space radiative lifetimes of OH⁻ ions (J=1,2) up to ~190 s were measured. An electron cooling device with a cryogenic (high-temperature superconducting) magnet and beam-merging system was taken into operation with an electron beam of ~40 eV from the TSR GaAs photocathode system*. It was applied to perform bunched-beam electron cooling of 1200 keV F(6+) ions. Future research will be devoted to interaction studies between stored atomic, molecular and cluster ions and laser, electron and neutral particle beams. Electron-beam studies (meV relative energies) will focus on dissociative recombination and state-changing collisions of molecular ions. R. von Hahn et al., Rev. Sci. Instr. 87, 063115 (2016) A. O'Connor et al., PRL 116, 113002 (2016) C. Meyer et al., PRL 119, 023202 (2017) ***D. Orlov et al., J. Appl. Phys. 106, 054907(2009)
	Slides WEM13 [9.830 MB]
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WEM21	Developing Analytical and Simulation Tools for a Coherent Electron Cooling System
	G. Wang, Y.C. Jing, V. Litvinenko, I. Pinayev, V. Samulyak BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA J. Ma, V. Samulyak SBU, Stony Brook, New York, USA
	While we are steadily approaching the experimental test of the coherent electron cooling (CeC) principle at RHIC, significant progresses have been made both in developing the techniques required for achieving optimal system configurations as well as improving the numerical simulation tools to make more accurate predictions of the cooling performance. By taking a new approach of extracting the subtle modulation signal induced by an ion, the one turn start-to-end simulation is substantially improved. Consequently, the initial beam distribution as generated from up-stream beam dynamics simulation as well as realistic beam optics are used to generate cooling force for a single pass of the cooling section. The single-pass cooling force is then applied to a separate hadron beam simulation code to predict the evolution of the hadron beam under the influences of cooling and intra-beam scattering (IBS). In the contribution, we will present the status of the numerical simulation of CeC as well as the analytical tools developed for benchmarking these simulations.
	Slides WEM21 [6.989 MB]
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THM11	Systematic Measurements with Electron Cooled Bunched Heavy Ion Beams
	R. Hess, C. Dimopoulou, M. Steck GSI, Darmstadt, Germany
	The results of systematic studies with electron-cooled bunched beams of highly charged ions at the Experimental Storage Ring ESR at GSI Helmholtzzentrum GmbH, Darmstadt are presented. The series of experiments were conducted during the beamtime block in 2016 for different ion species as well as ion beam energies. In these measurements, we recorded all three beam phase space planes simultaneously with high resolution, using a recently installed fast current transformer (to measure the bunch length, hence deduce the momentum spread) and ionization profile monitors (to measure horizontal and vertical emittances). A comparison of the results with those obtained with coasting beams is given as well.
	Slides THM11 [3.032 MB]
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THM12	ELENA: CERN and Extremely Low Energy Cooling
	L.V. Jørgensen CERN, Geneva, Switzerland
	The AD delivers antiprotons at 5.3 MeV. This is too high energy for the experiments, so >99.7% of antiprotons are lost. The solution: ELENA (Extra Low Energy Antiprotons) ' a new ring to decelerate the antiprotons further down to 100 keV. ELENA's circumference is 30.4 m (1/6 the size of the AD), it fits in available space in AD hall and allows installing all equipment without particular efforts. Lowest average field (beam rigidity over average radius) B'/R = 94 G (smaller than for AD 115 G). The talk will give an overview of ELENA and the layout with selected features and challenges, the status and an outlook of the next steps.
	Slides THM12 [34.851 MB]
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THM14	Overview of US Electron-ion Collider Project and its Beam Cooling Programs
	Y. Zhang JLab, Newport News, Virginia, USA
	Electron-Ion collider (EIC) utilizes deep-inelastic scatterings to probe structures of nucleus. HERA, the only e-p collider ever built and operated, ended its science program in 2007. Over the past 15 years, 7 next generation EICs were envisioned worldwide for high energy and nuclear physics. In the US, two electron-ion colliders, eRHIC and JLEIC, have been proposed in BNL and JLab respectively. The US EIC designs were guided by the science program (EIC White Paper). The US NSAC Long Range Plan (2015) recommended EIC as the next major facility in US for QCD frontier. If approved by DOE, construction will likely be completed around 2025. Cooling of proton/ion beams is essential for eRHIC and JLEIC to reach luminosity above 10³⁴/cm²/s. It enables emittance reduction up to an order of magnitude in all dimensions. eRHIC adopts the novel Coherent-electron-Cooling (CeC) concept. JLEIC has chosen magnetized electron cooling for the baseline, utilizing a multi-stage cooling scheme. Both CeC and high energy magnetized EC are under active development: BNL plans to conduct a proof-of-principle test of CeC at RHIC next year; JLab focuses on a technical design and technology development for a high energy bunched beam electron cooler based on ERL and circulator ring.
	Slides THM14 [35.872 MB]
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Paper

Title

Page

The Muon Ionization Cooling Experiment

1

M.A. Uchida
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The Muon Ionization Cooling Experiment (MICE) is designed to demonstrate a measurable reduction in muon beam emittance due to ionization cooling. This demonstration will be an important step in establishing the feasibility of muon accelerators for particle physics. The emittance of a variety of muon beams is measured before and after a "cooling cell", allowing the change in the phase-space distribution due to the presence of an absorber to be measured. Two solenoid spectrometers are instrumented with high-precision scintillating-fibre tracking detectors (Trackers) before and after the cooling cell which measure the normalized emittance reduction. Data has been taken since the end of 2015 to study several beams of varying momentum and input emittance as well as three absorber materials in the cooling cell, over a range of optics. The experiment and an overview of the analyses are described here.

Slides MOA12 [23.988 MB]

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TUM11

Low Energy Electron Cooler for the NICA Booster

22

A.V. Bubley, M.I. Bryzgunov, V.A. Chekavinskiy, A.D. Goncharov, K. Gorchakov, I.A. Gusev, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.V. Senkov
BINP SB RAS, Novosibirsk, Russia
A.V. Smirnov
JINR, Dubna, Moscow Region, Russia

The low energy electron cooler for the NICA booster has recently been installed at the booster ring of the NICA facility. The article describes results of various measurements obtained during its commissioning. Also some details of design and construction of the cooler are discussed.

Slides TUM11 [3.933 MB]

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TUM13

Electron Cooling at COSY - Status and Perspectives

V. Kamerdzhiev, A.J. Halama
FZJ, Jülich, Germany
M.I. Bryzgunov, V.V. Parkhomchuk, V.B. Reva
BINP SB RAS, Novosibirsk, Russia
T. Katayama
Nihon University, Narashino, Chiba, Japan

COSY, a COoler SYnchrotron and storage ring has been initially equipped with a low energy electron cooler. It was mainly used to improve the quality of the beams extracted to fixed-target experiments, to enable transverse stacking of polarized beams to be used with targets in the ring, and to improve the beam lifetime for internal experiments. In 2013 a high-energy e cooler covering the entire energy range of COSY was added. Since then high-energy e cooling has been demonstrated and dedicated cooling beam studies with dc and bunched proton beam have been carried out. Furthermore, the cooling process in presence of an internal cluster jet target continuously affecting the circulating beam was studied. We review the status of electron-cooling activities at COSY, present the latest experimental results, discuss problems encountered and possible cures, and provide insights into the activities envisaged for the next year.

Slides TUM13 [5.526 MB]

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TUM21

High Voltage Cooler NICA Status and Ideas

25

V.B. Reva, M.I. Bryzgunov, A.V. Bubley, A.D. Goncharov, N.S. Kremnev, V.M. Panasyuk, V.V. Parkhomchuk, V.A. Polukhin, A.A. Putmakov
BINP SB RAS, Novosibirsk, Russia

The new accelerator complex NICA is designed at the Joint Institute for Nuclear Research (JINR, Dubna, Russia) to do experiment with ion-ion and ion-proton collision in the range energy 1-4.5 GeV/u. The planned luminosity in these experiments is 10²⁷cm^-2c{-1}. This value can be obtained with help of very short bunches with small transverse size. This beam quality can be realized with electron and stochastic cooling at energy of the physics experiment. The subject of the report is the problem of the technical feasibility of fast electron cooling for collider in the energy range between 0.2 and 2.5 MeV. For the realization of the cooler device BINP team proposes the design that is like to COSY cooler. 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 when the ion interacts with Larmour circle and the cooling decrements are improved significantly. The cooling force at strong magnet field was measured at many experiments and can be surely estimated.

Slides TUM21 [50.456 MB]

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TUM22

Model Development for the Automated Setup of the 2 MeV Electron Cooler Transport Channel

28

A.J. Halama, V. Kamerdzhiev
FZJ, Jülich, Germany

The 2 MeV electron cooler allows for cooling the proton and deuteron beams in the entire energy range of COSY and thereby study magnetized high energy electron cooling for the HESR and NICA. Manual electron beam adjustment in the high energy, high current regime proves a cumbersome and time consuming task. Special difficulties are presented by the particular geometry of the e-beam transport channel, limited beam diagnostics and general technical limitations. A model has been developed to track electrons through the transport channel of the cooler. This allows the offline study of response schemes around any particular setting of the cooler. It is envisaged to control linear, dipole and quadrupole behavior of the e-beam. Application of the model will result in optimized e-beam transport settings for a lossless and cool beam transport. This will improve cooling and recuperation efficiency and allow quick adjustment of the e-beam to the various operational modes of the machine. A good relative agreement of the model and the cooler could be shown. Main focus lies now in overhauling the software and finding suitable initial conditions to improve the agreement to an absolute degree.

Slides TUM22 [3.784 MB]

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TUM23

Status of the Turbine Concept for Relativistic Electron Coolers

K. Aulenbacher
IKP, Mainz, Germany

A turbine driven high voltage section for manetized d.c. electron coolers may offer considerable advantages. This project is pursued in collaboration of BINP and Helmholtzinstitut Mainz. A 600kV prototype has seen first tests and will be installed in a pressurized tank at HIM in 2018. An outlook to further developments will be given.

Slides TUM23 [1.057 MB]

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TUP07

Secondary Electron and Photon Measurements at the HIM Electron Cooler Test Set-Up

Th. Beiser
IKP, Mainz, Germany
K. Aulenbacher, M.W. Bruker, T. Weilbach
HIM, Mainz, Germany

A low-energy test set-up for the measurement and optimisation of secondary electron currents from the collector in electron coolers is presented. A variable-field Wien filter and current-measuring aperture plates grant insight into the trajectory and energy distribution of the secondary particles. Photons emitted by residual gas ions trapped inside the electromagnetic potential of the electron beam can be used to measure the location of the beam. The exact composition of those ions, the optical spectrum of said photons, and the possibility of related beam diagnostics is a subject of ongoing research.

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TUP08

Preliminary Design of Electron Target for SRing at HIAF

40

J. Li, Z. Huang, L.J. Mao, M.T. Tang, S. X. Wang, J.C. Yang, X.D. Yang, H. Zhao, L.X. Zhao
IMP/CAS, Lanzhou, People's Republic of China

A 13 Tm multifunction storage ring dedicated to nucleon and atomic experiment research - the SRing (Spectrometry Ring) is a significant part of the new heavy-ion research complex - HIAF (High Intensity heavy ion Accelerator Facility). In additional to an electron cooler and a gas internal target planned at the SRing, a beam of low temperature electron is also required to collide with the storage beam and to cool the decelerated ion beam at low energy. A magnetic adiabatic expansion is proposed to attain a low temperature by applying a 1.2 T longitudinal magnetic field upon the thermionic cathode at the electron gun. In this paper, preliminary design of the electron target is introduced.

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TUP09

Project of High-Voltage System with Fast Changing Potential for DR Experiment

44

V.B. Reva, A.P. Denisov, V.V. Parkhomchuk, A.A. Putmakov, D.N. Skorobogatov
BINP SB RAS, Novosibirsk, Russia
J. Li, X. Ma, L.J. Mao
IMP/CAS, Lanzhou, People's Republic of China

Funding: The reported study was partially funded by RFBR 16-52-53016.
A storage ring equipped with an electron cooler is an ideal platform for dielectronic recombination (DR)experiments. In order to fulfill the requirement of DR measurements the system of the precision control of the relative energy between the ion beam and the electron beam should be installed in the electron cooler device. This report describes the project of such system that is designed with section approach like COSY electron cooler. Each section consist of the section of cascade transformer and two power supplies for low and fast detuning of potential of high-voltage terminal. This project can be used in CSRe and future HIAF storage rings.

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TUP10

Electron Cooling Simulation and Benchmarks

A. Latina, N. Biancacci
CERN, Geneva, Switzerland

Electron Cooling is a method of damping betratron oscillations of heavy particles, like protons, antiprotons, and ions, through the interaction with cold electrons at small relative velocity. A detailed simulation of the Electron Cooling process has been created using a hybrid kinetic model, where the full 6d phase space of a multi-particle beam is immersed in a fluid plasma of electrons. This simulation has been implemented in the tracking code RF-Track, with the aim of exploring the performance of electron coolers in presence of realistic imperfections. Simulations results, and benchmarks against experimental data measured at CERN at LEIR, are presented and discussed in this poster.

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TUP11

The Interaction Between Electrons and Ions in Comoving and Static Electron Columns

47

V.A. Britten, M. Droba, O. Meusel, H. Podlech, A. Schempp, K. Schulte
IAP, Frankfurt am Main, Germany

The interaction between electrons and positive ion beams and its application in accelerator physics are investigated. A space charge lens named Gabor lens was developed which confines electrons in a static column by external fields. The confined electrons are used for focusing and may support space charge compensation. In this structure the relative velocity between the ions and the electrons is maximal and corresponds to the beam velocity. An electron lens as at the Tevatron* is operated with a lower relative velocity in order to compensate the beam, to clean the beam abort gap or to excite the beam for beam dynamics measurements. In comparison electron cooling needs the same velocity of the ion and the electron beam. The following study contains the superposition of electric and magnetic self-fields and their impact on the density distribution of the ion beam and of the electron beam. Recombinations and ionisations are neglected. This is the beginning of an interface between these topics to find differences and similarities of the interaction between ions and electrons with different relative velocities. This may open up opportunities e.g. for the diagnostics of particle beams.
* Shiltsev, Vladimir, et al. "Tevatron electron lenses: Design and operation." Physical Review Special Topics-Accelerators and Beams 11.10 (2008): 103501.

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TUP12

Simulation of Low Enery Ion Beam Cooling With Pulsed Electron Beam on CSRm

50

H. Zhao, J. Li, L.J. Mao, M.T. Tang, J.C. Yang, X.D. Yang
IMP/CAS, Lanzhou, People's Republic of China

The pulsed electron beam can be applied to high ener-gy beam cooling and the researches of ion-electron inter-action in the future. In this paper, we studied the pulsed e-beam cooling effects on coasting and bunched ion beam by simulation code which is based on the theory of elec-tron cooling, IBS and space charge effect etc. In the simu-lation, a rectangular distribution of electron beam was applied to 7 MeV/u 12C⁶⁺ ion beam on CSRm. It is found that the coasting ion beam was bunched by the pulsed e-beam and the rising and falling region of electron beam current play an important role for the bunching effect, and similar phenomenon was found for the bunched ion beam. In addition, the analyses of these phenomena in simulation were discussed.

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TUP13

Calculations of the Gun and Collector for Electron Cooling Systems of HIAF

54

M.T. Tang, J. Li, H.J. Lu, X.M. Ma, L.J. Mao, T.L. Yan, X.D. Yang, H. Zhao, L.X. Zhao
IMP/CAS, Lanzhou, People's Republic of China
A.V. Ivanov
BINP SB RAS, Novosibirsk, Russia

Two electron coolers are designed for the new project HIAF, one cooler with the highest energy 50keV is for the booster ring (BRing) to decreasing the transverse emittance of injected beams and another one with the highest energy 450keV is for the high precision Spec-trometer Ring (SRing). In this paper the results of the gun and collector simulation for these two electron coolers are presented. After optimization, the gun can produce 2A profile variable electron beam. The one time collecting efficiency is higher than 99.99%. The results of electron motions in toroid calculated by a numerical method are also summarized in this paper.

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TUP14

Investigation on the Suppression of Intrabeam Scattering in the High Intensity Heavy Ion Beam with the help of Longitudinal Multi-bunch Chain of Electron

58

X.D. Yang, J. Li, X.M. Ma, L.J. Mao, M.T. Tang, T.L. Yan, H. Zhao
IMP/CAS, Lanzhou, People's Republic of China

Intrabeam scattering is the main reason of degradation of the beam brightness and shortening of brightness lifetime in the collider, light source and storage ring. The intrabeam scattering presents dissimilar influence in the different facilities. Electron cooling was chose to suppress the effect of intrabeam scattering, another unexpected effect happened during the cooling. The distribution of ion beam quickly deviates from the initial Gaussian type, form a denser core and long tail. The ions standing in the tail of beam will loss soon due to large amplitude. This solution will focus on the investigation on the suppression of intrabeam scattering in the high intensity heavy ion beam in the storage ring with the help of longitudinally modulated electron beam. The stronger cooling was expected in the tail of ion beam and the weaker cooling was performed in the tail of ion beam. The particle in the outside will experience stronger cooling and will be driven back into the centre of ion beam. The ion loss will be decreased and the lifetime will be increased. The intensity of ion beam in the storage ring will be kept and maintain for long time.

Poster TUP14 [4.160 MB]

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TUP15

Experimental Demonstration of Electron Cooling with Bunched Electron Beam

61

L.J. Mao, J. Li, X.M. Ma, M.T. Tang, J.C. Yang, X.D. Yang, H. Zhao, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
A. Hutton, K. Jordan, T. Powers, R.A. Rimmer, M. Spata, H. Wang, S. Wang, H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: This work was supported by the Hundred Talents Project of the Chinese Academy of Sciences and National Natural Science Foundation of China (Nos. 11575264, 11475235, 11375245)
Electron cooling at high energy is presently considered for several ion colliders, in order to achieve high luminosities by enabling a significant reduction of emittance of hadron beams. Electron beam at cooling channel in a few to tens MeV can be accelerated by a RF/SRF linac, and thus using bunched electrons to cool bunched ions. To study such cooling process, the DC electron gun of EC35 cooler was modified by pulsing the grid voltage, by which a 0.5-3.5 us of electron bunch length with a repetition frequency of less than 250 kHz was obtained. The first experiment demonstrated cooling coasting and bunched ion beam by a bunched electron beam was carried out at the storage ring CSRm at IMP. A preliminary data analysis has indicted the bunch length shrinkage and the momentum spread reduction of bunched 12C+6 ion beam. A longitudinal grouping effect of coasting ion beam by the electron bunch has also observed. In this paper, we will present the experiment result and its preliminary comparison to the simulation modeling.

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WEM11

Status of Bunched Beam Electron Cooler LEReC

A.V. Fedotov
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the U.S. Department of Energy.
The Low Energy RHIC electron Cooler (LEReC) system is presently under construction and commissioning at BNL. Although required energies of electron beam (few MeV) are not very high, an approach based on RF acceleration of electron beams was chosen. Required electron beam and its acceleration will be provided by the photoemission electron gun and the RF linear accelerator. As a result, cooling will be accomplished by using bunched electron beams produced by high-brightness high-current electron linear accelerator. Here, we describe design aspects and challenges of such an approach, as well as summarize status of the LEReC project. First commissioning results of the LEReC injector are also presented.
on behalf of the LEReC team.

Slides WEM11 [4.363 MB]

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WEM12

Development of a Bunched Beam Electron Cooler Based on ERL and Circulator Ring Technology for the Jefferson Lab Electron-Ion Collider

72

S.V. Benson, Y.S. Derbenev, D. Douglas, F.E. Hannon, A. Hutton, R. Li, R.A. Rimmer, Y. Roblin, C. Tennant, H. Wang, H. Zhang, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Jefferson Lab is in the process of designing an electron ion collider with unprecedented luminosity at a 45 GeV center-of-mass energy. This luminosity relies on ion cooling in both the booster and the storage ring of the accelerator complex. The cooling in the booster will use a conventional DC cooler similar to the one at COSY. The high-energy storage ring, operating at a momentum of up to 100 GeV/nucleon, requires the novel use of bunched-beam cooling. There are two designs for such a bunched beam cooler. The first uses a conventional Energy Recovery Linac (ERL) with a magnetized beam while the second uses a circulating ring to enhance both the peak and average current experienced by the ion beam. This presentation will describe the design of both the Circulator Cooling Ring (CCR) design and that of the backup option using the stand-alone ERL operated at lower charge but higher repetition rate than the ERL injector required by the CCR-based design.

Slides WEM12 [5.124 MB]

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WEM13

Electron Cooling of Bunched Ion Beams and Recent Results at the Heidelberg Cryogenic Storage Ring (CSR)

P. Wilhelm
MPI-K, Heidelberg, Germany

The cryogenic storage ring CSR is an electrostatic machine of 35 m circumference for positive and negative ions at up to 300 keV kinetic energy per charge. Vacuum chambers and ion optics are cooled to well below 10 K by a closed-cycle He system. Rest gas densities down to a room-temperature equivalent pressure of <10^-14 mbar and 1/e ion-beam lifetimes up to ~45 min were observed*. With rotationally cold diatomic ions, photodissociation Feshbach resonances of CH⁺ (J=0,1,2) were reported**. By time-dependent laser photodetachment, free-space radiative lifetimes of OH⁻ ions (J=1,2) up to ~190 s were measured***. An electron cooling device with a cryogenic (high-temperature superconducting) magnet and beam-merging system was taken into operation with an electron beam of ~40 eV from the TSR GaAs photocathode system****. It was applied to perform bunched-beam electron cooling of 1200 keV F(6+) ions. Future research will be devoted to interaction studies between stored atomic, molecular and cluster ions and laser, electron and neutral particle beams. Electron-beam studies (meV relative energies) will focus on dissociative recombination and state-changing collisions of molecular ions.
*R. von Hahn et al., Rev. Sci. Instr. 87, 063115 (2016)
**A. O'Connor et al., PRL 116, 113002 (2016)
***C. Meyer et al., PRL 119, 023202 (2017)
****D. Orlov et al., J. Appl. Phys. 106, 054907(2009)

Slides WEM13 [9.830 MB]

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WEM21

Developing Analytical and Simulation Tools for a Coherent Electron Cooling System

G. Wang, Y.C. Jing, V. Litvinenko, I. Pinayev, V. Samulyak
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
J. Ma, V. Samulyak
SBU, Stony Brook, New York, USA

While we are steadily approaching the experimental test of the coherent electron cooling (CeC) principle at RHIC, significant progresses have been made both in developing the techniques required for achieving optimal system configurations as well as improving the numerical simulation tools to make more accurate predictions of the cooling performance. By taking a new approach of extracting the subtle modulation signal induced by an ion, the one turn start-to-end simulation is substantially improved. Consequently, the initial beam distribution as generated from up-stream beam dynamics simulation as well as realistic beam optics are used to generate cooling force for a single pass of the cooling section. The single-pass cooling force is then applied to a separate hadron beam simulation code to predict the evolution of the hadron beam under the influences of cooling and intra-beam scattering (IBS). In the contribution, we will present the status of the numerical simulation of CeC as well as the analytical tools developed for benchmarking these simulations.

Slides WEM21 [6.989 MB]

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THM11

Systematic Measurements with Electron Cooled Bunched Heavy Ion Beams

R. Hess, C. Dimopoulou, M. Steck
GSI, Darmstadt, Germany

The results of systematic studies with electron-cooled bunched beams of highly charged ions at the Experimental Storage Ring ESR at GSI Helmholtzzentrum GmbH, Darmstadt are presented. The series of experiments were conducted during the beamtime block in 2016 for different ion species as well as ion beam energies. In these measurements, we recorded all three beam phase space planes simultaneously with high resolution, using a recently installed fast current transformer (to measure the bunch length, hence deduce the momentum spread) and ionization profile monitors (to measure horizontal and vertical emittances). A comparison of the results with those obtained with coasting beams is given as well.

Slides THM11 [3.032 MB]

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THM12

ELENA: CERN and Extremely Low Energy Cooling

L.V. Jørgensen
CERN, Geneva, Switzerland

The AD delivers antiprotons at 5.3 MeV. This is too high energy for the experiments, so >99.7% of antiprotons are lost. The solution: ELENA (Extra Low Energy Antiprotons) ' a new ring to decelerate the antiprotons further down to 100 keV. ELENA's circumference is 30.4 m (1/6 the size of the AD), it fits in available space in AD hall and allows installing all equipment without particular efforts. Lowest average field (beam rigidity over average radius) B'/R = 94 G (smaller than for AD 115 G). The talk will give an overview of ELENA and the layout with selected features and challenges, the status and an outlook of the next steps.

Slides THM12 [34.851 MB]

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THM14

Overview of US Electron-ion Collider Project and its Beam Cooling Programs

Y. Zhang
JLab, Newport News, Virginia, USA

Electron-Ion collider (EIC) utilizes deep-inelastic scatterings to probe structures of nucleus. HERA, the only e-p collider ever built and operated, ended its science program in 2007. Over the past 15 years, 7 next generation EICs were envisioned worldwide for high energy and nuclear physics. In the US, two electron-ion colliders, eRHIC and JLEIC, have been proposed in BNL and JLab respectively. The US EIC designs were guided by the science program (EIC White Paper). The US NSAC Long Range Plan (2015) recommended EIC as the next major facility in US for QCD frontier. If approved by DOE, construction will likely be completed around 2025. Cooling of proton/ion beams is essential for eRHIC and JLEIC to reach luminosity above 10³⁴/cm²/s. It enables emittance reduction up to an order of magnitude in all dimensions. eRHIC adopts the novel Coherent-electron-Cooling (CeC) concept. JLEIC has chosen magnetized electron cooling for the baseline, utilizing a multi-stage cooling scheme. Both CeC and high energy magnetized EC are under active development: BNL plans to conduct a proof-of-principle test of CeC at RHIC next year; JLab focuses on a technical design and technology development for a high energy bunched beam electron cooler based on ERL and circulator ring.

Slides THM14 [35.872 MB]

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