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 $25\pi \mathrm{nm}\mathrm{rad}$ and $3\times 1\pi \mathrm{mm}\mathrm{GeV}$, 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 (${\mu }^{+}$, ${\mu }^{-}$, and $e^{+}$) at two different energies ($\mu$ at 22 GeV and $e^{+}$ at 44 GeV), where the line is specially designed to match the muon beam phase space over $\pm 5\%$ 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.

中文翻译：

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来自+ ni灭的多个薄靶上的纳米μ子束发射

低发射μ子束的产生对于μ子对撞机项目很有趣。在这种情况下，我们研究了在22 GeV下正负介子束的产生${Ë}^{+}$ 光束与固定目标碰撞，具有很小的横向和纵向发射率 $25\pi \mathrm{纳米}\mathrm{拉德}$ 和 $3\times \mathrm{1个}\pi \mathrm{毫米}\mathrm{GeV}$， 分别。为了应对正电子转换成μ对子的效率低以及光束发散的问题，我们通过仅四极传输线将薄靶连接到三个光束（${\mu }^{+}$， ${\mu }^{-}$和 ${Ë}^{+}$）在两种不同的能量（$\mu$ 在22 GeV和 ${Ë}^{+}$ （在44 GeV处），该线是专门设计来匹配整个 $\pm 5％$能量散布并减轻目标在所有光束上的多次散射的影响。传输线使我们能够使用更大比例的靶材料，使每个正电子束中的μ子数量增加10倍，并将功率沉积分配到20到40个靶上，同时保持μ子束的发射率等于或类似于一个。辐射长度的1％的单个薄目标。可以将这条线集成到一个累加器环中，以增加数百个正电子束中的μ子束。