DarkLight at TRIUMF/ARIEL -- A Search for New Physics in e+e- Final States with an Invariant Mass between 10-20 MeV.

今天在粒子物理学和宇宙学中仍有许多未解之谜。虽然我们现在有一个非常成功的粒子物理学标准模型（SM），它将4种已知力中的3种联系起来，但很明显，标准模型是不完整的。它不包含任何暗物质（DM）粒子，也无法解释暗能量（DE），暗能量是能量预算的最大组成部分，是宇宙加速膨胀的原因。此外，我们可见的宇宙只占宇宙总质量的5%左右，而暗物质占了23%左右。寻找对难以捉摸的糖尿病的理解是我们这个时代最伟大的科学探索之一。根据我们目前的理解，已知的不带电粒子，即三种中微子，不可能是推断出的暗物质质量的主要组成部分，因此我们假设至少存在一种尚未观测到的新粒子。最近，人们关注的焦点是质量为e- Ta a ' -> e- Ta （e+e-）的新第五力的介质。使用ARIEL电子直线加速器的好处是允许相对较低的光束能量，从而减少产生的玻色子的增强，并打开这些向前衰变轻子的小角度。为了获得足够的亮度，我们提出了一种针对异常区域和薄片目标优化的双光谱仪装置。这些磁铁将由麻省理工学院的研究小组设计和制造。每个光谱仪将配备一个焦平面探测器，由3个GEM探测器组成，通过标准APV电子设备读出。他们将由汉普顿大学小组提供。GEMs之后将有一层闪烁的桨作为快速触发探测器。由加拿大机构（UBC, Manitoba, Saint Mary's， TRIUMF和Winnipeg）组成的财团将设计和建造闪烁体。他们还将为触发系统提供读出电子设备，并处理与ARIEL加速器的集成。石溪大学将负责数据采集和慢速控制系统。在第二阶段的实验中，TRIUMF将安装一个束线减速弯，允许电子束通过加速腔再循环，以将束能量增加到50兆电子伏，并扩大实验的范围。如果我们的CFI提案成功，TRIUMF还将安装第二个低温模块，以在单用户模式下将光束能量提高到75 MeV，并允许在50 MeV下同时运行DL和ARIEL，以显着增加我们的实验范围。

There are still many unanswered questions today in particle physics and cosmology. Although we now have a highly successful Standard Model (SM) of particle physics that links 3 of the 4 known forces it is very clear that the SM is incomplete. It does not contain any Dark Matter (DM) particles and it cannot explain Dark Energy (DE) which is the largest component of the energy budget and is responsible for the accelerating expansion of the universe. Moreover, our visible universe makes up only about 5% of the total mass of the universe while DM contributes about 23%. The search for an understanding of the elusive DM is one of the greatest scientific quests of our age. In our current understanding, the known, uncharged particles, the three neutrinos, cannot be a major component of the inferred dark matter mass, and so we posit at least one as-yet unobserved new particle. Recently, there has been a focus on a mediator of a new fifth force with mass e- Ta A' --> e- Ta (e+e-). The use of the ARIEL e-linac has the benefit of allowing a relatively low beam energy, thus reducing the boost of the produced boson and opening up the small angles of these forward-going decay leptons. We propose a two spectrometer setup optimized for the anomaly region and a thin foil target to achieve sufficient luminosity. The magnets will be designed and constructed by the MIT group. Each spectrometer will be instrumented with a focal plane detector consisting of 3 GEM detector planes, read out via standard APV electronics. They will be provided by the Hampton University group. The GEMs will be followed by a layer of scintillating paddles as the fast trigger detectors. A consortium of Canadian institutions (UBC, Manitoba, Saint Mary's, TRIUMF, & Winnipeg) will design & construct the scintillators. They will also provide the readout electronics for the trigger system and handle the integration with the ARIEL accelerator. Stony Brook University will take care of the data acquisition and slow control system. In a 2nd stage experiment TRIUMF would install a beamline chicane to allow re-circulation of the electron beam through the accelerating cavity to increase the beam energy to 50 MeV and extend the reach of the experiment. If our CFI proposal is successful TRIUMF would also install a 2nd cryomodule to increase the beam energy up to 75 MeV in single user mode and allow simultaneous operation of DL and ARIEL at 50 MeV to significantly increase the reach of our experiment.