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| MOPAB177 | ELENA Commissioning and Status | proton, experiment, MMI, electron | 598 |
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| The Extra Low ENergy Antiproton ring ELENA is a small synchrotron recently constructed and commissioned to decelerate antiprotons injected from the Antiproton Decelerator AD with a kinetic energy of 5.3 MeV down to 100 keV. Controlled deceleration in the synchrotron, equipped with an electron cooler to reduce losses and generate dense bunches, allows the experiments, typically capturing the antiprotons in traps and manipulating them further, to improve the trapping efficiency by one to two orders of magnitude. During 2018, bunches with an energy of 100 keV with parameters close to nominal have been demonstrated, and first beams have been provided to an experiment in a new experimental zone. The magnetic transfer lines from the AD to the experiments have been replaced by electrostatic lines from ELENA. Commissioning of the new transfer lines and, in parallel, studies to better understand the ring with H− beams from a dedicated source, have started in autumn 2020. The first 100 keV antiproton physics run using ELENA will start in late summer 2021. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB177 | ||
| About • | paper received ※ 18 May 2021 paper accepted ※ 14 June 2021 issue date ※ 23 August 2021 | ||
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| MOPAB267 | End to End Simulations of Antiproton Transport and Degradation | simulation, proton, experiment, electron | 847 |
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| The ELENA ring decelerates anti-protons to 100 keV down from 5.3 MeV with transport to experiments handled by electrostatic transfer lines. Even at 100 keV antiprotons are still too high in energy for direct injection into an ion trap, and this is why degrader foils are used to further lower the energy. This contribution presents full end-to-end simulations from the point of extraction until passing through the foil using realistic beam transport simulations coupled with accurate simulations of degrader foils via the use of density functional theory and molecular dynamics. Particles are tracked from the point of extraction until their injection into the trap with full physical modeling at all time steps. The results of this study provide a versatile platform for the optimization of low energy ion experiments towards specific targets. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB267 | ||
| About • | paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 24 August 2021 | ||
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| WEPAB152 | Carbon Nanotubes as Cold Electron Field Emitters for Electron Cooling in the CERN Extra Low Energy Antiproton (ELENA) Ring | electron, vacuum, proton, experiment | 2975 |
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| In ELENA electron cooling reduces the emittance of the antiproton beam allowing to deliver a high-quality beam to the experiments at the unprecedented low energy of 100 keV. To cool the antiproton beam at this low energy, the electron gun must emit electrons with as monoenergetic a distribution as possible. The currently used thermionic gun limits the cooling performance due to the relatively high transverse energy spread of the emitted electrons. Optimization is therefore being studied, aiming at developing a cold-cathode electron gun. This has led to the investigation of carbon nanotubes (CNTs) as cold electron field emitters. CNTs are considered the most promising field emitter material due to their high aspect ratio, chemical stability, and capability to deliver high current densities. To assess the feasibility of using such material operationally a full characterization is required, focussing on key parameters such as emitted current, emission stability, and lifetime. This contribution will present the status of ongoing experiments reporting on the conditioning process necessary to reach good stability over time and the emitting performance of different CNT arrays. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB152 | ||
| About • | paper received ※ 18 May 2021 paper accepted ※ 25 June 2021 issue date ※ 16 August 2021 | ||
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| WEPAB181 | New Opportunities in Low Energy Antiproton Research | electron, proton, experiment, FEL | 3035 |
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Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 721559. Experiments with low-energy antiprotons are at the cutting edge of science and offer unique opportunities to test some of the fundamental laws of physics. The experiments are, however, very difficult to realize. They critically depend on high-performance numerical tools that can model realistic beam transport and storage and also require advanced beam monitors and detectors that can fully characterize the beam. Finally, novel experiments need to be designed that exploit the enhanced beam quality that the new ELENA ring at CERN provides. This paper presents some selected findings from the pan-European AVA network’s three scientific work packages. It shows results from studies into electron cooling at the new ELENA storage ring, research into carbon nanotubes as cold electron field emitters for electron cooling, and how antiproton-atom collision experiments can be optimized using GEANT4. Finally, the paper gives an overview of the network’s interdisciplinary training program. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB181 | ||
| About • | paper received ※ 16 May 2021 paper accepted ※ 11 June 2021 issue date ※ 11 August 2021 | ||
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| WEPAB213 | Optimization of Antiproton-Atom Collision Studies Using GEANT4 | proton, experiment, simulation, bunching | 3126 |
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Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559. The interaction between antiprotons and hydrogen or helium atoms is a fundamental problem in many-particle atomic physics, attracting strong interest from both theory and experiments. Atomic collisions are ideal to study the three and four-body Coulomb problem as the number of possible reaction channels is limited. Currently, only the total cross-sections of such interactions have been measured in an energy range between keV and a few MeV. This contribution investigates the discrepancies between different theories and available experimental data. It also describes a pathway for obtaining differential cross-sections. A purpose-designed experimental setup is presented and detailed Geant4 simulations provide an insight into the interaction between short (ns) antiproton bunches and a dense gas-jet target. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB213 | ||
| About • | paper received ※ 23 May 2021 paper accepted ※ 30 June 2021 issue date ※ 24 August 2021 | ||
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| WEPAB214 | Realistic Simulations of Stray Field Impact on Low Energy Transfer Lines | solenoid, experiment, simulation, proton | 3130 |
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Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559. Low energy (~100 keV) facilities working with antiprotons, heavy ions, or charged molecules may experience severe beam transport instabilities caused by field imperfections. For example, long (~10 m), unshielded beamlines will not be able to transfer particles due to the natural Earth magnetic field or stray fields from closely located experiments. Currently, only a limited number of simulation codes allow a simplified representation of such field errors, limiting capabilities for beam delivery optimization. In this contribution, a new simulation approach is presented that can provide detailed insight into 4D beam transport. It illustrates the impact of imperfections and stray fields on beam stability and quality through simulations of two antiproton experiments located in the Antimatter Factory (AD) at CERN in Geneva, Switzerland. Magnetic field imperfections are examined in two different ways, providing greater flexibility and an opportunity to benchmark all outcomes. Simulation performance is analyzed as a function of the level of detail and efficiency. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB214 | ||
| About • | paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 18 August 2021 | ||
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| WEPAB366 | Towards the Last Stages of the CERN’s AD-Target Area Consolidation Project and Recommissioning Plans to Resume Operation | target, proton, operation, MMI | 3563 |
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| Antiprotons are produced at CERN at the Antiproton Decelerator (AD) Target Area by impacting 26 GeV/c proton beams onto a fixed target. Further collection, momentum selection, and transport of the secondary particles - including antiprotons - towards the AD ring is realised by a 400 kA pulsed magnetic horn and a set of magnetic dipoles and quadrupoles. A major consolidation of the area - in operation since the 80s - has taken place during the CERN Long Shutdown 2 (2019-2021). Among other activities, such upgrade included: (i) Installation of a new air-cooled target design and manufacturing of a new batch of magnetic horns, including a surface pulsing test-bench for their validation and fine-tuning (ii) Installation of a new positioning and maintenance system for the target and horn (iii) Refurbishment and decontamination of the Target Area and its equipment, (iv) Construction of a new surface service building to house new nuclear ventilation systems. This contribution presents an overview of such activities and lesson learnt. In addition, it provides the latest results from refractory metals R&D for the antiproton target and a summary of the recommissioning and optimization plans. | |||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB366 | ||
| About • | paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 01 September 2021 | ||
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| THXA06 | The Effect of Beam Velocity Distribution on Electron-Cooling at Elena | electron, proton, emittance, simulation | 3700 |
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Funding: Work supported by EU Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721559. ELENA is a novel storage ring at CERN, designed to deliver low energy, high-quality antiprotons to antimatter experiments. The electron cooler is a key component of this decelerator, which counters the beam blow-up as the antiproton energy is reduced from 5.3 MeV to 100 keV. Typical numerical approximations on electron cooling processes assume that the density distribution of electrons in analytical form and the velocity distribution space to be Maxwellian. However, it is useful to have an accurate description of the cooling process based on a realistic electron distribution. In this contribution, BETACOOL simulations of the ELENA antiproton beam phase space evolution were performed using uniform, Gaussian, and "hollow beam" electron velocity distributions. The results are compared with simulations considering a custom electron beam distribution obtained with G4beamline. The program was used to simulate the interaction of an initially Gaussian electron beam with the magnetic field measured inside the electron cooler interaction chamber. The resulting beam lifetime and equilibrium parameters are then compared with measurements. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXA06 | ||
| About • | paper received ※ 18 May 2021 paper accepted ※ 01 July 2021 issue date ※ 14 August 2021 | ||
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