Testing Einstein's equivalence principle at Bremen Drop Tower using LTS SQUID technique

A new experimental baseline for testing the weak equivalence principle at the Bremen drop tower

“…To determine the sensitivity of the measuring system we inclined the cryostat and measured the corresponding acceleration, the SQUID signal, and the position of the test mass, as a function of the pick-up current. The pick-up current I and the sensor's sensitivity x are related by [6] x ∝ 1 I .…”

“…This current causes an inductance signal in a SQUID coupling coil and is, therefore, detected by the SQUID. The sensor is described explicitly in [6,7], and so it will not be discussed further in this paper.…”

An innovative method for simulating microgravity effects through combining electromagnetic force and buoyancy

“…The drop tower in Bremen (ZARM, Germany) is a widely used device; it is 146 m high and has a steel tube in it; the tube's diameter is 3.5 m and its length is 110 m. The drop tower can achieves 10 À6 g for 4.74 s and is mainly used for scientific experiments (Vodel et al, 2001). The drop tower in China's National Microgravity Laboratory at the Chinese Academy of Sciences has the height of over 100 m and achieves 10 À5 g for 3.5 s. USA and Japan also have similar facilities, some of which have the height of over 700 m and can achieve 10 À4 g for 10 s. Under the Zero-G condition, the time interval of the drop tower is even less than that of the parabolic flight.…”

Satellite Eötvös test of the weak equivalence principle for zero-point vacuum energy

“…In terms of the standard Eötvös parameter η, they have reached sensitivities of η ∼ 1.1 × 10 −12 in comparisons of the accelerations of Be and Al/Cu test masses [7] and, more recently, have resolved differential accelerations of approximately 1.0 × 10 −14 cm/s 2 in experiments with other masses [8]. Drop-tower experiments now underway in Germany [9] have as their goal testing WEP at sensitivities of η ∼ 1 × 10 −13 , and Unnikrishnan describes a methodology under study at the Tata Institute of Fundamental Research in India wherein torsion balance experiments aiming at sensitivities of η ∼ 1 × 10 −14 are being developed [10] While it is not yet clear what ultimate sensitivities might be reached by terrestrial experiments of these types, it is generally accepted that significant gains in sensitivity will be made by space-based WEP experiments, and several of them are presently in various stages of planning and development. Among these are the STEP satellite [11], the MICROSCOPE experiment [12], the Galileo Galelei (GG) mission [13], and Project SEE [14].…”