论文标题
Dimus：Fermilab的超紧凑型Dimunium光谱对照筒
DIMUS: Super-Compact Dimuonium Spectroscopy Collider at Fermilab
论文作者
论文摘要
尽管尚未观察到dimuonium $（μ^+μ^ - ）$，但它具有最大的基本兴趣。借助较大的质量，二酮对超出标准模型效应的敏感性要比其表亲的阳性或蒙马群更高，两者都在很久以前发现，同时却没有大量的QCD不确定性。可以在$ e^+e^ - $碰撞的情况下以较大的纵向动量创建dimuonium原子，从而使其衰减距离横梁交叉点的距离很小，并避免及时的背景。我们设想了一个独特的成本效益和快速速度的机会，可以通过对Fermilab现有的Fast/NML现有的Fast/NML设施进行适度的修改，以安排408 MeV电子和pocitrons的碰撞，以75 $^{\ rm o} $角度来安排408 mev电子和正面的碰撞，从而在生产阈值下大量生产$（μ^+μ^ - ）$原子。这个紧凑的23 m圆周对撞机（Dimus）将允许对QED进行精确测试，并打开门以搜索与MUON结合的新物理学。 Fermilab的快速/NML非常适合Dimus，因为现有的SRF加速器和基础架构能够生产高能量，高电流和正电子光束，足以$ O（10^{32}）\ Mathrm {Cm}扩展将需要安装第二个SRF冷冻模块，正电子生产和积累系统，快速注入/提取踢球和两个小圆周相交环。大约仪表尺寸的检测器，具有几层现代像素化硅探测器和基于晶体的电磁热量表，将确保在存在Bhabba散射背景的情况下观察到Dimuonium到电子峰值对的衰变。该系统的扩展将扩展Dimus的物理计划，以包括对Muons，Pions和$η$ Mesons在$ e^{+} e^{ - } $ collisions中生产的稀有过程的精确研究。
While dimuonium $(μ^+μ^-)$ has not yet been observed, it is of utmost fundamental interest. By virtue of the larger mass, dimuonium has greater sensitivity to beyond the standard model effects than its cousins positronium or muonium, both discovered long ago, while not suffering from large QCD uncertainties. Dimuonium atoms can be created in $e^+e^-$ collisions with large longitudinal momentum, allowing them to decay a small distance away from the beam crossing point and avoid prompt backgrounds. We envision a unique cost-effective and fast-timeline opportunity for copious production of $(μ^+μ^-)$ atoms at the production threshold via a modest modification of Fermilab's existing FAST/NML facility to arrange collisions of 408 MeV electrons and positrons at a 75$^{\rm o}$ angle. This compact 23 m circumference collider (DIMUS) will allow for precision tests of QED and open the door for searches for new physics coupled to the muon. Fermilab's FAST/NML is perfectly suited for DIMUS as there are existing SRF accelerators and infrastructure, capable of producing high energy, high current electron and positron beams, sufficient for $O(10^{32})\mathrm{cm}^2\mathrm{s}^{-1}$ luminosity and $\sim$0.5 million dimuons per year. The expansion will require installation of a second SRF cryomodule, positron production and accumulation system, fast injection/extraction kickers and two small circumference intersecting rings. An approximately meter-sized detector with several layers of modern pixelated silicon detector and crystal-based electromagnetic calorimeters will ensure observation of the decays of dimuonium to electron-positron pairs in presence of the Bhabba scattering background. An expansion of the system to would extend the physics program of DIMUS to include precision studies of rare processes with muons, pions, and $η$ mesons produced in $e^{+}e^{-}$ collisions.
