A magnetically shielded room with ultra low residual field and gradient

Abstract

A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within a central volume of 1 m × 1 m × 1 m and a field gradient less than 300 pT/m, achieved without any external field stabilization or compensation, is described. This performance represents more than a hundredfold improvement of the state of the art for a two-layer magnetic shield and provides an environment suitable for a next generation of precision experiments in fundamental physics at low energies; in particular, searches for electric dipole moments of fundamental systems and tests of Lorentz-invariance based on spin-precession experiments. Studies of the residual fields and their sources enable improved design of future ultra-low gradient environments and experimental apparatus. This has implications for developments of magnetometry beyond the femto-Tesla scale in, for example, biomagnetism, geosciences, and security applications and in general low-field nuclear magnetic resonance (NMR) measurements.

Minimizing magnetic fields for precision experiments

“…8 The shielding factor of an MSR is given as the frequency dependent attenuation of external disturbances…”

Round Table: Resolving Physics BSM at Low Energies

“…At the SNS [42], PSI [43], ILL [44], and TUM [45] there are different, ongoing efforts to measure the neutron EDM with a sensitivity below 10 −27 e·cm. The techniques use either ultracold neutrons (UCN) produced and stored in superfluid helium or UCN provided by a dedicated source, with the experiment at room temperature.…”

Experimental study of ultracold neutron production in pressurized superfluid helium

“…This peculiarity makes them attractive for high-precision measurements of fundamental properties of the neutron which are relevant for particle physics and cosmology [2]. The most prominent example is their use for searches of a neutron electric dipole moment [3][4][5][6][7][8] which would give direct evidence of CP violation beyond the standard model of particle physics. Other projects aim to improve the knowledge of the neutron β-decay lifetime, which is crucial for calculations of big-bang nucleosynthesis [9].…”