Leptonic CP-Violation with ESSνSB: Design and Simulations of the 4-Horn Target Station

ESSνSB 的轻子 CP 破坏：4 喇叭目标站的设计和仿真

• 批准号: 423761110
• 负责人: Dr. Tamer Tolba, Ph.D.
• 金额: --
• 依托单位: Institut für Experimentalphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/423761110?language=en
• 关键词: Leptonic; CP; Violation; ESS; SB

Based on the tiny differences in how matter and antimatter behave at the scale of elementary particles, known as charge-parity, CP-, violation, scientists believe that there is some subtle asymmetry between them, and that soon after the Big Bang, this led to a universe dominated by matter. The current problem is that not enough CP-violation has been observed, and that the Standard Model (SM) also does not predict enough to explain the observed asymmetry. The so-called “neutrino oscillations” phenomenon convincingly indicates that neutrinos do have mass, contradicting the SM hypotheses. Recent results from reactor experiments have shown that the third mixing angle, θ13 , is higher than its previously defined standard value, with a value of ~ 9°, opening a new window for discovering and measuring a nonzero value of the Dirac leptonic CP violating angle, δ_CP. Moreover, the T2K experiment has recently reported new results on the δ_CP, where they disfavored almost half of its possible values at the 99.7% (3σ) confidence. In the light of these new findings, an urgent need raised to improve the detection sensitivity of the current long-baseline detectors, with a key modification to place the far detectors at the second, rather than the first, oscillation maximum. Many of the presently planned detectors are the ones that use “intense” neutrino beams, such as DUNE in the USA, T2HK in Japan and ESSνSB in Europe. While the design of the US and Japanese experiments aim for measurement at the first-, the ESSvSB will measure at the second- oscillation maximum, leading to a significantly higher sensitivity to CP‐violation compared to the other two experiments. Several technological challenges must be precisely studied before addressing the design of the ESSνSB detector. Among these, the design and physics of the target station and the neutrino beam considered highest priority at this phase of the project. UHH represents Germany in the project, as an associate member, since September 2019. The strategic objective of this DFG-proposal is to continue and extend this unique contribution. This contribution will be continued within the neutrino group of the IEP-UHH. The specific objectives of the proposal are: 1- Optimization of the hadron-collector (horn) design in order to increase the charge current, CC, events at the detector, hence the neutrino beam characteristics; flux and profile. 2 -Perform full radiation, energy deposition and activation calculations in the different parts and shields of the ESSνSB target station. 3- Define the baseline design for the target station and its internal components, which will be introduced in the ESSνSB CDR at the end of phase-I, and later in the TDR.I strongly believe that continuing such involvement through the UHH in such unique project will undoubtedly reinforce the role that the German neutrino physics community, in general, and that of the UHH, in particular, plays, nationally and internationally, in this field.

基于物质和反物质在基本粒子尺度上行为的微小差异，科学家们认为，它们之间存在一些微妙的不对称，在大爆炸后不久，这导致了一个由物质主导的宇宙。目前的问题是，没有观察到足够的CP破坏，标准模型(SM)也没有足够的预测来解释观察到的不对称性。所谓的“中微子振荡”现象令人信服地表明中微子确实有质量，这与SM假说相矛盾。反应堆实验的最新结果表明，第三混合角θ13高于其先前定义的标准值，其值为~9°，为发现和测量狄拉克轻子CP破坏角δ_CP的非零值打开了新的窗口。此外，T2K实验最近报道了关于δ_CP的新结果，在99.7%(3σ)的置信度下，他们几乎不支持其可能值的一半。鉴于这些新的发现，迫切需要提高目前长基线探测器的探测灵敏度，并对Far探测器进行关键修改，将其置于第二个而不是第一个最大振荡位置。目前计划中的许多探测器都是使用“强”中微子束的探测器，例如美国的沙丘探测器、日本的T2HK探测器和欧洲的essνsb探测器。虽然美国和日本实验的设计目标是第一次测量，但ESSvSB将在第二个振荡最大值进行测量，导致与其他两个实验相比，对CP破坏的敏感度明显更高。在解决ESSνSb探测器的设计之前，必须精确研究几个技术挑战。其中，目标站和中微子束的设计和物理被认为是该项目这一阶段的最优先事项。UHH自2019年9月以来作为准成员代表德国参与该项目。这项DFG建议的战略目标是继续和扩大这一独特的贡献。这一贡献将在IEP-UHH的中微子群内继续进行。该提案的具体目标是：1-优化强子收集器(喇叭)设计，以增加探测器上的电荷电流、CC、事件，从而提高中微子束特性；通量和轮廓。2-在ESSνSB目标站的不同部分和屏蔽体中执行完整的辐射、能量沉积和激活计算。3-确定目标站及其内部部件的基线设计，这将在第一阶段结束时在欧洲空间站νSB CDR中引入，并随后在TDR中引入。我坚信，通过UHH继续参与这一独特的项目，无疑将加强德国中微子物理界，特别是UHH在国内和国际上在这一领域发挥的作用。