Elucidating the fundamental nature of hadrons with Particle Identification Detector

用粒子识别探测器阐明强子的基本性质

• 批准号: ST/W005433/1
• 负责人: Mikhail Bashkanov
• 金额: $ 3.02万
• 依托单位: University of York
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FW005433%2F1
• 关键词: Elucidating; fundamental; nature; hadrons; Particle

In this application we request a timely and cost-effective UK equipment contribution to next generation science programmes with the CrystalBall@MAMI. This new research landscape is enabled by the commissioning of a new high-rate time projection chamber (TPC) which can operate with intense, energetic photon beams. The TPC will be constructed by the end of 2022 with experiments running in 2023. The TPC will provide charged particle tracking with exquisite accuracy and, for the first time, will allow us to detect low energy recoiling nuclei (protons, deuterons, heavier species) following photoreactions. The latter aspect opens up exciting scientific possibilities for the UK at MAMI and this new capability aligns well with our highest impact research goals. The measurement programme will provide key information on the fundamental properties of the new d* hexaquark particle. Additionally, with the TPC there are new and exciting prospects to study in detail the in-medium interaction of the d*, using the dominant and clean d* resonance peaks accessible with nuclear recoil tagging.As we recently showed, hexaquarks might also coexist inside neutron stars effectively restricting the maximum allowed neutron star size at exactly the value determined by LIGO and NICER. We have also shown that primordinary produced hexaquark condensate might play a role of dark-matter particles. To elaborate this concept, one needs to investigate hexaquark behaviour inside the nuclear medium. It can be done in a laboratory environment, and then apply the results to the nuclear equation of state (EoS) of neutron stars.York leads a major CB@MAMI programme aiming to accurately determine the size and shape of neutron skins, using the method of coherent pion photoproduction. Accurate skin determinations are a powerful discriminator for nuclear theories; DFT and ab-initio predictions predict widely varying skin thicknesses, highlighting how accurate measurements will provide crucial missing information for nuclear science. The neutron skin also correlates with the most poorly constrained and elusive parameter in the EoS for nucleonic matter, the density dependence of the symmetry energy (L). The TPC allows measurement of momentum transfer to the nuclear recoil with greatly reduced systematics, enables much improved separation of coherent and incoherent processes, opens up new target possibilities (e.g. noble gases like Xenon) and for subsequent gamma spectroscopy on the recoil nuclei can veto unwanted backgrounds from nuclear breakup.

在此申请中，我们请求英国设备通过 CrystalBall@MAMI 为下一代科学计划做出及时且具有成本效益的贡献。这一新的研究领域是通过新型高速时间投影室 (TPC) 的调试实现的，该室可以使用强、高能光子束进行操作。 TPC 将于 2022 年底建成，并于 2023 年进行实验。TPC 将提供高精度的带电粒子跟踪，并将首次使我们能够检测光反应后的低能反冲核（质子、氘核、较重的物质）。后一方面为英国 MAMI 开辟了令人兴奋的科学可能性，这一新能力与我们最高影响力的研究目标非常契合。测量程序将提供有关新 d* 六夸克粒子基本特性的关键信息。此外，利用 TPC，利用可通过核反冲标记获得的主要且干净的 d* 共振峰，详细研究 d* 的介质内相互作用有新的、令人兴奋的前景。正如我们最近所表明的，六夸克也可能共存于中子星内部，有效地将允许的最大中子星尺寸限制在 LIGO 和 NICER 确定的值上。我们还表明，原初产生的六夸克凝聚态可能起到暗物质粒子的作用。为了阐述这一概念，需要研究核介质内的六夸克行为。它可以在实验室环境中完成，然后将结果应用于中子星的核状态方程（EoS）。York 领导了一个主要的 CB@MAMI 项目，旨在使用相干介子光产生方法精确确定中子表皮的尺寸和形状。准确的皮肤测定是核理论的有力判别器； DFT 和从头算的预测预测了广泛变化的皮肤厚度，强调了精确的测量将如何为核科学提供重要的缺失信息。中子皮还与 EoS 中核子物质约束最差、最难以捉摸的参数（对称能 (L) 的密度依赖性）相关。 TPC 可以在大大减少系统性的情况下测量向核反冲的动量传递，大大改善相干和非相干过程的分离，开辟新的目标可能性（例如氙等惰性气体），并且反冲核上的后续伽马能谱可以否决核破裂中不需要的背景。