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首页> 外文期刊>Classical and Quantum Gravity: An Interantional Journal of Gravity Geometry of Field Theories Supergravity Cosmology >'Galileo Galilei' (GG): Space test of the weak equivalence principle to 10 ~(-17) and laboratory demonstrations
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'Galileo Galilei' (GG): Space test of the weak equivalence principle to 10 ~(-17) and laboratory demonstrations

机译：“伽利略伽利略”（GG）：弱等效原理对10〜（-17）的空间测试和实验室演示

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摘要

The small satellite Galileo Galilei (GG) will test the universality of free fall and hence the weak equivalence principle which is the founding pillar of general relativity to 1 part in 10 ~(17). It will use proof masses whose atoms differ substantially from one another in their mass energy content, so as to maximize the chance of violation. GG will improve by four orders of magnitude the current best E?t-Wash tests based on slowly rotating torsion balances, which have been able to reach their thermal noise level. In GG, the expected violation signal is a relative displacement between the proof masses of 0.6pm caused by a differential acceleration a _(GG) 8 × 10 ~(17)ms ~2 pointing to the center of mass of the Earth as the satellite orbits around it at ν _(GG) 1.7 × 10 ~4Hz. GG will fly an innovative acceleration sensor based on rapidly rotating macroscopic test masses weakly coupled in 2D which up-converts the signal to ν _(spin) 1Hz, a value well above the frequency of natural oscillations of the masses relative to each other ν _d = 1/T _d 1/(540s). The sensor is unique in that it ensures high rotation frequency, low thermal noise and no attenuation of the signal strength (Pegna et al 2011 Phys. Rev. Lett. 107 200801). A readout based on a very low noise laser interferometry gauge developed at Jet Propulsion Laboratory (1pmHz ~(1/2) at 1Hz demonstrated) allows the short integration time to be fully exploited. A full scale sensor with the same degrees of freedom and the same dynamical features as the one to fly in GG has been setup on ground (GGG). The proof masses of GGG are affected by acceleration and tilt noise acting on the rotating shaft because of ball bearings and terrain microseismicity (both absent in space). Overall, by means of appropriate 2D flexure joints, these noise sources have been reduced by a factor almost 10 ~5 down to a differential acceleration between the proof masses of 7 × 10 ~(11)ms ~2 (at 1.7 × 10 ~4Hz up-converted by rotation to 0.2Hz). The corresponding noise in the relative displacements of the proof masses, read by co-rotating capacitance bridges, is 180pm, which is 300 times larger than the target in space. GGG error budget shows that it can reach a differential acceleration sensitivity a _(GGGgoal) 8 × 10 ~(16)ms ~2, not limited by thermal noise. This value is only a factor 10 larger than what GG must reach in space to meet its target, and slightly smaller than the acceleration noise of the torsion balance. It can be achieved partly by means of weaker joints and an optimized mechanical design - so as to improve the attenuation factor - and partly by replacing the current ball bearings with much less noisy air bearings (also used in torsion balance tests) so as to reduce input noise. A laser gauge readout with noise level r _(laser-ro) 30pmHz ~(1/2) at 0.2÷3Hz will be implemented.
机译：小型卫星伽利略伽利略（GG）将测试自由落体的普遍性，并因此测试弱当量原理，这是广义相对论在10〜（17）中建立的基础。它将使用原子质量能量含量互不相同的证明质量，以便最大化违反的机会。 GG将基于缓慢旋转的扭力平衡将目前最佳的E-t-Wash测试提高四个数量级，这些平衡已经能够达到其热噪声水平。在GG中，预期违规信号是由指向地球质心作为卫星的微分加速度a _（GG）8×10〜（17）ms〜2引起的0.6pm证明质量之间的相对位移。围绕它以ν_（GG）1.7×10〜4Hz旋转。 GG将飞行一种创新的加速度传感器，该传感器基于快速旋转的二维微弱测试质量块，将信号上转换为ν_（自旋）1Hz，该值远高于质量块相对于彼此的自然振荡频率νd = 1 / T _d 1 /（540s）。该传感器的独特之处在于，它确保了高旋转频率，低热噪声且信号强度没有衰减（Pegna等人2011 Phys。Rev. Lett。107 200801）。基于Jet Propulsion实验室开发的超低噪声激光干涉仪的读数（已证明1pmHz〜（1/2）在1Hz时），可以充分利用较短的积分时间。已在地面（GGG）上设置了一种与GG飞行相同的自由度和动态特性的满量程传感器。由于球轴承和地形微震（两者都不存在），GGG的标准质量受作用在旋转轴上的加速度和倾斜噪声的影响。总体而言，通过适当的2D挠性接头，这些噪声源已减小了将近10〜5倍，下降到了7×10〜（11）ms〜2（在1.7×10〜4Hz的质量）之间的差分加速度旋转向上转换为0.2Hz）。通过同向旋转的电容电桥读取的检测质量相对位移中的相应噪声为180pm，这是空间目标的300倍。 GGG误差预算表明它可以达到8×10〜（16）ms〜2的差分加速度灵敏度a_（GGGgoal），不受热噪声的限制。该值仅比GG在空间中达到目标要达到的大小大10倍，并且比扭转平衡的加速度噪声小一些。它可以部分通过较弱的接头和优化的机械设计来实现-以提高衰减系数-部分可以通过用噪音少得多的空气轴承替换当前的球轴承（也用于扭力平衡测试）来减少输入噪声。将实现在0.2÷3Hz的噪声水平r _（laser-ro）30pmHz〜（1/2）的激光测量仪读数。

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