Precision Ultra-low Magnetic Field Measurement Device

一个高性能的步入式大小的磁屏蔽外壳正在被要求，用于精密测量的基础物理和应用。其主要特征是背景磁场< 0.1 nT，中心1 m3的梯度为0.1 nT/m。这对于进入几个学科的新实验领域至关重要。商用大型屏蔽外壳的剩余磁场和梯度仅限于约1 nT/m，可与德国联邦物理技术研究所（Physikalisch-Technische Bundesanstalt）的世界上最大的屏蔽体相媲美。慕尼黑工业大学的“极端条件下的精密测量”主席在过去的13年里在设计极端屏蔽环境方面积累了丰富的经验，这是由寻找中子电偶极矩的要求引发的，这是一项基础物理学实验。为此，在两个仅采用被动屏蔽措施且噪声< 1 fT的装置中，在m3大小的体积上证明了<0.1 nT的场和< 0.1 nT/m的梯度。性能的关键是（i）壁材料（通常称为高导磁合金的可磁化合金）内部磁畴取向的优化以及（ii）用于准确和精确感测的措施。这里提出的屏蔽环境包括一个由高导磁率可磁化材料和高导电性外壳组成的嵌套外壳、用于产生磁场和磁平衡的线圈、一个宽1.15米、高2米的气动门，用于各种实验和人员的进出;非磁性5轴机器人、磁通门和原子磁力计用于磁场和梯度表征，以确保条件可以表征、优化和再现。新设施为不同研究学科的测量提供服务，以实现基础物理学与物理学，医学和神经科学应用之间的技术和知识转移。计划通过多功能概念为不同的研究项目共享该设施。计划中的活动包括（i）精密自旋钟测量，以极高的精度探索自然规律（电偶极矩和类轴子粒子搜索）和开发新的实验;（二）开发基于量子和纳米/微制造MEMS的（量子）磁力计;（三）胎儿心脏磁成像技术开发（胎儿MCG）结合补充诊断方法，如超声成像和（iv）调查大脑的磁信号（MEG）与身体的运动和运动。所有这些活动都需要极低的磁场梯度，并使用类似的技术。我们将利用新设施不断推进低磁场技术，并配备专门的工作人员，以确保设施的正常运行，并为所有设想的应用提供通道。

A high-performance walk-in sized magnetically shielded enclosure is being requested, to be used for precision measurements in fundamental physics and applications. Its main features are a magnetic background field of < 0.1 nT and a gradient of 0.1 nT/m in the central 1 m3. This is essential to access new experimental terrain in several disciplines. Commercial large-scale shielded enclosures are limited to approximately 1 nT residual fields and gradients of nT/m, comparable to the world’s largest shield at the Physikalisch-Technische Bundesanstalt. The chair for ‘Precision Measurements at Extreme Conditions’ at TU München gained significant experience over the last 13 years in the design of extremely shielded environments, triggered by the requirements for the search for the electric dipole moment of the neutron, an experiment in fundamental physics. For this, a field of < 0.1 nT and a gradient of < 0.1 nT/m over a m3 - sized volume was demonstrated in two installations only with passive shielding measures with < 1 fT noise. Key to the performance is (i) the optimization of the orientation of magnetic domains inside the wall material, a magnetizable alloy often called mumetal and (ii) measures for accurate and precise sensing. The shielded environment proposed here consists of an enclosure of nested shells of a highly permeable magnetizable material and a highly conducting shell, coils for generating magnetic fields and for magnetic equilibration; a pneumatic door with 1.15 m width and 2 m height for access for various experiments and people; a non-magnetic 5-axes robot, fluxgate- and atomic magnetometers for field and gradient characterization to ensure that the conditions can be characterized, optimized, and reproduced. The new facility serves measurements in different disciplines of research, to enable technology and knowledge transfer between fundamental physics and applications in physics, medicine and neuroscience. It is planned to share the facility for different research projects through a versatile concept. Planned activities are (i) precision spin clock measurements to probe the laws of nature at extreme precision (Electric Dipole Moment and Axion-like particle searches) and the development of novel experiments; (ii) development of quantum- and nano/micro-fabricated MEMS based (quantum) magnetometers; (iii) technology development for magnetic fetal heart imaging (fetal MCG) in combination with complementary diagnostic methods like ultrasound imaging and (iv) investigation of the brain’s magnetic signals (MEG) in connection to motion and movement of the body. All these activities share the need for extremely low magnetic field gradients and use similar techniques. We will use the new facility to continuously advance low magnetic field technology with dedicated staff personnel to ensure proper operation of the facility and to provide access for all envisaged applications.