LZD Development: the LUX-ZEPLIN Multi Tonne Dark Matter Experiment Technical Development Plan for DUSEL

暗物质的发现对宇宙学、天体物理学和基本粒子物理学具有重要意义。广泛的观测表明，宇宙中80%到90%的物质是某种新的物质形式。由此产生的标准宇宙学认为，宇宙能量密度的四分之一是实验室中尚未遇到的一种新的基本物质形式，其余大部分是暗能量。这个谜团的答案可能在于某种新的通用类弱相互作用大质量粒子的存在，这种粒子的存在也是由超越粒子相互作用标准模型的物理驱动的。WIMP探测实验需要在地下深处进行操作，以防止宇宙线相互作用产生假阳性信号。LUX和ZEPLIN的合作，基于他们在液体氙气(LXE)暗物质探测器方面的开创性工作，以及他们在低本底技术和罕见事件搜索方面的广泛专业知识，在这里提出了一项20吨LXE探测器(LZ20)的设计计划。LZ20探测器将使用成熟的两相LXE技术，读出用于粒子识别的一次和二次闪烁信号，以及3D位置重建，以利用LXE的自我屏蔽、去除表面伪影和校准位置相关响应函数。该探测器安装在4850级，基准质量为13.5吨，初始运行周期为1000天，将抑制从电磁和中子相互作用到单个事件以下的内部和外部背景，并实现对WIMP相互作用的灵敏度，从10的横截面到负48 cm2的功率。在这次曝光中，灵敏度将开始遇到来自太阳和大气中微子相互作用的不可还原的背景。因此，这项实验代表了可以用液体X进行的明确的WIMP搜索。关于更广泛的影响，暗物质科学正在广泛地吸引公众，这是建立在公众的自然好奇心以及对引力的联系和熟悉的基础上的。该合作计划开展一系列活动，从参观和展示到与当地学校和个人的合作，以培养人们对科学和科学事业的兴趣。暗物质实验需要开发对辐射超敏感的新技术，以及实现超低放射性背景的新方法。这些技术和方法与广泛的核安全背景下使用的技术和方法有重叠之处。通过直接技术开发或通过培训在职业生涯后期转移到工业或国防实验室的人员，合作预计LZ20将产生重大影响，特别是因为LLNL的参与。该提案包括对博士后指导计划的描述。

The discovery of dark matter is of fundamental importance to cosmology, astrophysics, and elementary particle physics. A broad range of observations indicate that 80 to 90% of the matter in the universe is in some new form of matter. The resulting Standard Cosmology holds that a quarter of the energy density of the universe is a new fundamental form of matter not yet encountered in the laboratory, and most of the remainder is dark energy. The solution to this mystery may lie in the existence of some new generic class of Weakly Interacting Massive Particles, or WIMPs, whose existence is also motivated by physics beyond the standard model of particle interactions. WIMP detection experiments require operation deep underground to prevent cosmic ray interactions from causing false positive signals. The LUX and ZEPLIN collaborations, building on their pioneering efforts in liquid xenon (LXe) dark matter detectors and their broad expertise in low background techniques and rare event searches, propose here a plan for the design of a 20-ton LXe detector (LZ20). The LZ20 detector will use established two-phase LXe technology with readout of primary and secondary scintillation signals for particle identification together with 3d position reconstruction to exploit the self-shielding of the LXe, removal of surface artifacts and calibration of position dependent response functions. This detector, installed at the 4850 level, with a fiducial mass of 13.5 tons and an initial operating period of 1000 days, will suppress internal and external backgrounds from electromagnetic and neutron interactions to below a single event and achieve a sensitivity to WIMP-interactions down to cross section of 10 to the power negative 48 cm2. At this exposure, the sensitivity will begin to encounter irreducible backgrounds from solar and atmospheric neutrino interactions this experiment therefore represents the definitive WIMP search that can be performed with liquid Xe.Regarding Broader Impacts Dark Matter science is broadly appealing to the public, building on the natural curiosity of the public as well as the connection and familiarity with gravity. The collaboration proposes to develop a range of activities, from tours and displays to partnerships with local schools and individuals, to foster an interest in science and science careers. Dark matter experiments demand the development of new technologies that are ultra-sensitive to radiation, and new methods for achieving ultra-low radioactive backgrounds. There is an overlap of these technologies and methods with those used in a wide range of nuclear security contexts. Through direct technology development or through the training of personnel that transfer to industry or defense labs later in their careers, the collaboration expects significant impact from LZ20 particularly because of the involvement of LLNL. This proposal includes a description of postdoctoral mentoring plans.