Quantum dark matter detection through the intersection of particle physics, chemistry and solid state physics

Research Project

Project/Area Number	22K18712
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Review Section	Medium-sized Section 15:Particle-, nuclear-, astro-physics, and related fields
Research Institution	The University of Tokyo
Principal Investigator	Melia Thomas 東京大学, カブリ数物連携宇宙研究機構, 准教授 (30814909)
Co-Investigator(Kenkyū-buntansha)	福井智也東京工業大学, 科学技術創成研究院, 助教 (40808838) 水上雄太東北大学, 理学研究科, 准教授 (80734095)
Project Period (FY)	2022-06-30 – 2024-03-31
Project Status	Granted (Fiscal Year 2022)
Budget Amount *help	¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000) Fiscal Year 2023: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000) Fiscal Year 2022: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Keywords	Dark Matter / Particle Detector / Single Molecule Magnet
Outline of Research at the Start	The nature of the Dark Matter (DM) we observe in the universe has been a mystery for nearly a century. This proposal is to develop a new quantum DM detector using a novel type of chemical crystal with an approach at the intersection of particle physics, synthetic chemistry, and solid-state physics.
Outline of Annual Research Achievements	The particle theory group (including PI Melia) is responsible for the theoretical calculations that identify particular single molecule magnets out of the 100s of possible choices that would be well suited to dark matter detection. We identified a number of possibilities, and importantly we identified a key parameter that acts as an indicator for the energy threshold. This parameter - a constant that determines the fastest possible magnetic relaxation time - is well documented for the synthesized single molecule magnets in the literature. We therefore were able to target of order ten crystals, with the properties chosen so that the energy threshold would sit on a sliding scale, with an eye to making future potential prototype particle detectors. The chemistry group (including Co-I Fukui) is responsible for the synthesis of single molecule magnets. The group selected single-molecule magnets focusing on the spin relaxation time, and synthesized single-molecule magnets containing manganese ions. As a result, single crystals of two types of single-molecule magnets were successfully prepared. The condensed matter group (including Co-I Mizukami) is responsible for the heat capacity measurement on crystals of single molecule magnets synthesized by the chemistry group. They have been provided several single-crystalline samples of Mn-based compounds, and determined the temperature dependence of specific heat in magnetic fields.
Current Status of Research Progress	Current Status of Research Progress 2: Research has progressed on the whole more than it was originally planned. Reason The pipeline for measuring the relevant physical properties, namely the heat capacity of the crystals, their energy barrier, and their relaxation time, has been successfully demonstrated. The synthesis of some of the targeted chemical crystals was hindered by poor crystallization yield, due to lack of reported synthesis information.
Strategy for Future Research Activity	The project will continue by applying the knowledge and techniques above and survey the remaining targeted single molecule magnets. We expect to achieve the stated goal of the research, namely to measure the key physical parameters of a number of promising single molecule magnets for detectors of light dark matter.