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.

在这个应用程序中，我们要求及时和具有成本效益的英国设备贡献下一代科学计划CrystalBall@MAMI。这种新的研究景观是由一个新的高速率时间投影室（TPC）的调试实现的，该室可以使用强烈的高能光子光束。TPC将于2022年底建成，2023年进行实验。TPC将提供精确的带电粒子跟踪，并将首次允许我们探测光反应后的低能反冲核（质子、氘核、更重的物质）。后一个方面为MAMI的英国开辟了令人兴奋的科学可能性，这种新的能力与我们最高影响力的研究目标是一致的。该测量计划将提供有关新型d*六夸克粒子基本特性的关键信息。此外，利用核反冲标记可以获得的主要和干净的d*共振峰，利用TPC详细研究d*在介质中的相互作用具有新的和令人兴奋的前景。正如我们最近所展示的，六夸克也可能共存于中子星内部，有效地限制了中子星的最大允许尺寸，正好是LIGO和NICER确定的值。我们也证明了原初产生的六夸克凝聚物可能扮演了暗物质粒子的角色。为了阐述这一概念，我们需要研究核介质中的六夸克行为。它可以在实验室环境中进行，然后将结果应用于中子星的核状态方程（EoS）。约克领导了一个主要的CB@MAMI项目，旨在使用相干介子光产生的方法精确地确定中子表皮的大小和形状。准确的皮肤测定是核理论的有力鉴别器；DFT和ab-initio预测预测了广泛变化的皮肤厚度，突出了精确的测量将如何为核科学提供关键的缺失信息。中子蒙皮也与核物质动力学中约束最差、最难捉摸的参数——对称能(L)的密度依赖性有关。TPC可以测量动量转移到核后坐力，大大减少了系统，使相干和非相干过程的分离得到了很大的改善，开辟了新的目标可能性（例如稀有气体，如氙），后坐力核的后续伽马能谱可以阻止核分裂的不必要背景。