Optics studies of a Muon Accumulator Ring based on FFA cells

The production of an intense, high energy and low emittance muon beam is interesting for a possible muon collider. The Low EMittance Muon Accelerator (LEMMA) team at the Istituto Nazionale di Fisica Nucleare (INFN), in Italy, is studying the production of a 22.5 GeV low emittance muon beam from a high energy positron beam at twice the muon energy impinging on a fixed thin target. The LEMMA scheme proposes to perform the muon accumulation from multiple ($10^2$ to $10^3$) positron bunches to increase the population of a single muon bunch that is recirculated through the target using two small accumulator rings, one per muon species. The three beams ($\mu^+$ and $\mu^-$ at 22.5 GeV and $e^+$ at twice the muon energy) share the same phase space at the target on every positron bunch interaction, producing new muons inside the preserved beam emittance. We study the requirements and optics design of the accumulator to recirculate the muons over the target using a Fixed Field Alternating Gradient (FFA) arc. As a result, we achieve a compact 230 m long accumulator with two Interaction Points, energy acceptance of $\pm5$ %, low twiss beta function at the target $\beta^*_\mu=20$ cm, and a drift space 2$L^*$ of 20 cm enough to accommodate 1 % of a radiation length $X_0$ for several material options. These optics parameters are obtained with magnets similar to those foreseen for new colliders like FCC or CLIC, and could be extended further with new magnet designs. The current muon accumulation results will serve as input for beam combination studies.Comment: Low emittance muon accumulation studie

Nanometric muon beam emittance from e + annihilation on multiple thin targets

The production of a low emittance muon beam is interesting for muon collider projects. In such context we study the production of positive and negative muon beams at 22 GeV, from ${e}^{+}$ beam-vs-fixed target collisions, with a very small transverse and longitudinal emittance of 25\text{ }\text{ }\ensuremath{\pi}\text{ }\mathrm{nm}\text{ }\mathrm{rad} and 3\ifmmode\times\else\texttimes\fi{}1\text{ }\text{ }\ensuremath{\pi}\text{ }\mathrm{mm}\text{ }\mathrm{GeV}, respectively. In order to cope with the small conversion efficiency of positrons into muon pairs and the divergence of the beams, we connect thin targets by a quadrupole-only transport line common to three beams ({\ensuremath{\mu}}^{+}, {\ensuremath{\mu}}^{\ensuremath{-}}, and ${e}^{+}$) at two different energies (\ensuremath{\mu} at 22 GeV and ${e}^{+}$ at 44 GeV), where the line is specially designed to match the muon beam phase space over \ifmmode\pm\else\textpm\fi{}5% energy spread and to mitigate the effect of multiple scattering with the targets on all beams. The transport line allows us to use a larger fraction of target material, increasing the muon population by a factor of 10 per positron bunch and splitting the power deposition over 20 to 40 targets, while keeping the muon beam emittance equal or similar to one from a single thin target of 1% of a radiation length. It might be possible to integrate this line into an accumulator ring in order to increase the muon bunch population over hundreds of positron bunches

Muon production and accumulation from positrons on target

In this paper we investigate the production of a muon beam by positrons on target. We describe the characteristics of the muon beam as produced by different target configurations. We present an optics for the muon accumulator ring, discussing how it fulfils the large energy acceptance requirement and the high order chromaticity correction at the target, as well as other parameters relevant to enhance the muon bunch quality. We discuss the muon beam dynamics through the ring for the configuration of the single-pass LEMMA scheme, and the optimization study performed with the goals of maximizing the muon bunch population and minimizing its emittance

The status of the interaction region design and machine detector interface of the FCC-ee

We present the latest development for the FCC-ee interaction region. It represents a major challenge for the FCC-ee collider, which has to achieve extremely high luminosity over a wide range of centre-of-mass energies. The FCC-ee will host two or four high-precision experiments. The machine parameters have to be well controlled and the design of the machine-detector-interface has to be carefully optimized. In particular, the complex final focus hosted in the detector region has to be carefully designed, and the impact of beam losses and of any type of radiation generated in the interaction region, including beamstrahlung, have to be simulated in detail. We discuss mitigation measures and the expected impact of beam losses and radiation on the detector background. We also report the progress of the mechanical model of the interaction region layout, including the engineering design of the central beampipe, and other MDI components

The CLAS12 Forward Tagger

This document presents the technical layout and the performance of the CLAS12 Forward Tagger (FT). The FT, composed of an electromagnetic calorimeter based on PbWO4 crystals (FT-Cal), a scintillation hodoscope (FT-Hodo), and several layers of Micromegas trackers (FT-Trk), has been designed to detect electrons and photons scattered at polar angles from 2∘ to 5∘ and to meet the physics goals of the hadron spectroscopy program and other experiments running with the CLAS12 spectrometer in Hall B

Study of the production of a low emittance muon beam for the LEMMA project

The Low EMittance Muon Accelerator (LEMMA) is a concept for a positron-driven muon source for a future multi-TeV muon collider, which aims to produce a low emittance muon beam via positron-electron annihilation overcoming the need to cool the beam. I will describe the principles of this concept together with the first results of the muon production studies. I will also discuss the 6D emittance evolution through the production line for the single-target configuration. These studies have been performed with a novel simulation code developed for this purpose

Study of the production of a low emittance muon beam for the LEMMA project

The Low EMittance Muon Accelerator (LEMMA) is a concept for a positron-driven muon source for a future multi-TeV muon collider, which aims to produce a low emittance muon beam via positron-electron annihilation overcoming the need to cool the beam. I will describe the principles of this concept together with the first results of the muon production studies. I will also discuss the 6D emittance evolution through the production line for the single target configuration. These studies have been performed with a novel simulation code developed for this purpose

Nanometric muon beam emittance from e+ annihilation on multiple thin targets

The production of a low emittance muon beam is interesting for muon collider projects. In such context we study the production of positive and negative muon beams at 22 GeV, from e+ beam-vs-fixed target collisions, with a very small transverse and longitudinal emittance of 25 πnm rad and 3×1 πmm GeV, respectively. In order to cope with the small conversion efficiency of positrons into muon pairs and the divergence of the beams, we connect thin targets by a quadrupole-only transport line common to three beams (μ+, μ-, and e+) at two different energies (μ at 22 GeV and e+ at 44 GeV), where the line is specially designed to match the muon beam phase space over ±5% energy spread and to mitigate the effect of multiple scattering with the targets on all beams. The transport line allows us to use a larger fraction of target material, increasing the muon population by a factor of 10 per positron bunch and splitting the power deposition over 20 to 40 targets, while keeping the muon beam emittance equal or similar to one from a single thin target of 1% of a radiation length. It might be possible to integrate this line into an accumulator ring in order to increase the muon bunch population over hundreds of positron bunches

Optics studies of a Muon Accumulator Ring based on FFA cells

The production of an intense, high energy and low emittance muon beam is interesting for a possible muon collider. The Low EMittance Muon Accelerator (LEMMA) team at the Istituto Nazionale di Fisica Nucleare (INFN), in Italy, is studying the production of a 22.5 GeV low emittance muon beam from a high energy positron beam at twice the muon energy impinging on a fixed thin target. The LEMMA scheme proposes to perform the muon accumulation from multiple ($10^2$ to $10^3$) positron bunches to increase the population of a single muon bunch that is recirculated through the target using two small accumulator rings, one per muon species. The three beams ($mu^+$ and $mu^-$ at 22.5 GeV and $e^+$ at twice the muon energy) share the same phase space at the target on every positron bunch interaction, producing new muons inside the preserved beam emittance. We study the requirements and optics design of the accumulator to recirculate the muons over the target using a Fixed Field Alternating Gradient (FFA) arc. As a result, we achieve a compact 230 m long accumulator with two Interaction Points, energy acceptance of $pm5$ %, low twiss beta function at the target $eta^*_mu=20$ cm, and a drift space 2$L^*$ of 20 cm enough to accommodate 1 % of a radiation length $X_0$ for several material options. These optics parameters are obtained with magnets similar to those foreseen for new colliders like FCC or CLIC, and could be extended further with new magnet designs. The current muon accumulation results will serve as input for beam combination studies