| Paper | Title | Page |
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| WEPOST009 | Muon Collider Based on Gamma Factory, FCC-ee and Plasma Target | 1691 |
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Funding: This project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No 101004730 (iFAST). The LEMMA-type muon collider generates muon pairs by the annihilation of 45 GeV positrons with electrons at rest. Due to the small cross section, an extremely high rate of positrons is required, which could be achieved by a ’Gamma factory’ based on the LHC. Other challenges with the LEMMA-type muon production scheme include the emittance preservation of muons and muon-generating positrons upon multiple traversals through a target, and the merging of many separate muon bunchlets. These two challenges may potentially be overcome by (1) operating the FCC-ee booster with a barrier bucket and induction acceleration, so that all positrons of a production cycle are merged into one single superbunch instead of storing ~10,000 separate bunches; and (2) sending the positron superbunch into a plasma target. During the passage of the positron superbunch, the electron density is enhanced 100–1000 fold without any increase in the density of nuclei, so that beamstrahlung and Coulomb scattering are essentially absent. We investigate prospects and difficulties of this approach, including emittance growth due to filamentation in the nonlinear plasma channel and due to positron self-modulation. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOST009 | |
| About • | Received ※ 08 June 2022 — Revised ※ 23 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 05 July 2022 | |
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| WEPOPT012 | MAD-X for Future Accelerators | 1858 |
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| The development of MAD-X was started more than 20 years ago and it still remains the main tool for single particle dynamics for both optics design, error studies as well as for operational model-based software at CERN. In this article, we outline some of the recent development of MAD-X and plans for the future. In particular, we focus on the development of the twiss module used to calculate optics functions in MAD-X which is based on first and second order matrices. These have traditionally been calculated as an expansion around the ideal orbit. In this paper, we describe explicitly how an expansion around the closed orbit can be employed instead, in order to get more precise results. We also describe the latest development of the beam-beam long range wire compensator in MAD-X, an element that has been implemented using the aforementioned approach. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT012 | |
| About • | Received ※ 08 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 01 July 2022 | |
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| WEPOPT062 | Optimisation of the FCC-ee Positron Source Using a HTS Solenoid Matching Device | 2003 |
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| In this paper, we present the simulation and optimisation of the FCC-ee positron source, where a high-temperature superconducting (HTS) solenoid is used as the matching device to collect positrons from the target. The "conventional" target scheme is used which simply consists of amorphous tungsten. The target is placed inside the bore of the HTS solenoid to improve the accepted positron yield at the entrance of the damping ring and the location of the target is optimised. The latest recommended baseline beam parameters are used and presented. An optimisation of the ideal positron yield using the analytic SC solenoid on-axis field is also performed and shows that the design of the HTS solenoid is optimal as far as the accepted positron yield is concerned. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT062 | |
| About • | Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 16 June 2022 | |
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| WEPOPT063 | The FCCee Pre-Injector Complex | 2007 |
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| The international FCC study group published in 2019 a Conceptual Design Report for an electron-positron collider with a centre-of-mass energy from 90 to 365 GeV with a beam currents of up to 1.4 A per beam. The high beam current of this collider create challenging requirements on the injection chain and all aspects of the linac need to be carefully reconsidered and revisited, including the injection time structure. The entire beam dynamics studies for the full linac, damping ring and transfer lines are major activities of the injector complex design. A key point is that any increase of positron production and capture efficiency reduces the cost and complexity of the driver linac, the heat and radiation load of the converter system, and increases the operational margin. In this paper we will give an overview of the status of the injector complex design and introduce the new layout that has been proposed by the study group working in the context of the CHART collaboration. In this framework, furthermore, we also present the preliminary studies of the FCC-ee positron source highlighting the main requirements and constraints. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT063 | |
| About • | Received ※ 11 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 29 June 2022 | |
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| THPOST019 | Generation of Transversely Uniform Bunches from a Gaussian Laser Spot in a Photoinjector for Irradiation Experiments | 2483 |
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| Beams of uniform transverse beam profile are desirable for a variety of applications such as irradiation experiments. The generation of beams with such profiles has previously been investigated as a method of reducing emittance growth. These methods, however, often use complicated optics setups or short, femtosecond laser pulse lengths. In this paper, we demonstrate that if ultra low emittance is not the target of the photoinjector, it is possible to produce transversely uniform beam profiles using a simple Gaussian laser, with a bunch length of a few picoseconds, utilising space-charge effects only. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST019 | |
| About • | Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 16 June 2022 | |
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| THPOTK048 | Radiation Load Studies for the FCC-ee Positron Source with a Superconducting Matching Device | 2879 |
| SUSPMF118 | use link to see paper's listing under its alternate paper code | |
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| For an electron-positron collider like FCC-ee, the production of positrons plays a crucial role. One of the design options considered for the FCC-ee positron source employs a superconducting solenoid made of HTS coils as an adiabatic matching device. The solenoid, which is placed around the production target, is needed to capture positrons before they can be accelerated in a linear accelerator. A superconducting solenoid yields a higher peak field than a conventional-normal conducting magnetic flux concentrator, therefore increasing the achievable positron yield. In order to achieve an acceptable positron production, the considered target is made of tungsten-rhenium, which gives also a significant flux of un-wanted secondary particles, that in turn could generate a too large radiation load on the superconducting coils. In this study, we assess the feasibility of such a positron source by studying the heat load and long-term radiation damage in the superconducting matching device and surrounding structures. Results are presented for different geometric configurations of the superconducting matching device. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK048 | |
| About • | Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 07 July 2022 | |
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| THPOMS020 | Beam Optics Study for a Potential VHEE Beam Delivery System | 2992 |
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| VHEE (Very High Energy Electron) therapy can be superior to conventional radiotherapy for the treatment of deep seated tumours, whilst not necessarily requiring the space and cost of proton or heavy ion facilities. Developments in high gradient RF technology have allowed electrons to be accelerated to VHEE energies in a compact space, meaning that treatment could be possible with a shorter linac. A crucial component of VHEE treatment is the transfer of the beam from accelerator to patient. This is required to magnify the beam to cover the transverse extent of the tumour, whilst ensuring a uniform beam distribution. Two principle methodologies for the design of a compact transfer line are presented. The first of these is based upon a quadrupole lattice and optical magnification of beam size. A minimisation algorithm is used to enforce certain criteria on the beam distribution at the patient, defining the lattice through an automated routine. Separately, a dual scattering-foil based system is also presented, which uses similar algorithms for the optimisation of the foil geometry in order to achieve the desired beam shape at the patient location. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOMS020 | |
| About • | Received ※ 19 May 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022 | |
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