The cold atom gravimeter (CAG) has proven to be a powerful quantum sensor for the high-precision measurement of gravity field, which can work stably for a long time in the laboratory. However, most CAGs cannot operate in the field due to their complex structure, large volume and poor environmental adaptability. In this paper, a home-made, miniaturized CAG is developed and a truck-borne system based on it is integrated to measure the absolute gravity in the field. The measurement performance of this system is evaluated by applying it to measurements of the gravity field around the Xianlin reservoir in Hangzhou City of China. The internal and external coincidence accuracies of this measurement system were demonstrated to be 35.4 μGal and 76.7 μGal, respectively. Furthermore, the theoretical values of the measured eight points are calculated by using a forward modeling of a local high-resolution digital elevation model, and the calculated values are found to be in good agreement with the measured values. The results of this paper show that this home-made, truck-borne CAG system is reliable, and it is expected to improve the efficiency of gravity surveying in the field.

重力场是反映地球质量分布及变化的重要参数, 动态重力测量在地质调查、地球物理、资源勘探等领域有着重要应用. 目前动态重力测量均基于相对测量原理, 动态相对重力仪存在零点漂移问题, 影响其测量性能. 动态绝对重力仪可以为相对重力仪提供同步同址校准, 解决其长漂问题, 因此备受关注. 本文基于原子重力仪和惯性稳定平台, 搭建了一套船载绝对重力动态测量系统, 并在船载系泊状态下开展了绝对重力动态测量实验. 经评估, 船载系泊环境下的重力测量灵敏度为16.6 mGal/Hz^–1/2, 1000 s积分时间内重力测量的分辨率可达0.7 mGal. 通过两周的绝对重力测量, 评估了系统的稳定性. 为了评估绝对重力的动态测量精度, 将船上测量点与码头高精度绝对重力基准点的绝对重力值进行了比较, 两点之间的绝对重力值差及其不确定度评估结果为(–0.072 ± 0.134) mGal. 本文结果为海洋相对重力仪的同时同船校准提供了一种新方案.

The cold atom absolute gravimeters are intrinsically sensitive to its orientation due to the Coriolis effect, which should be understood clearly and compensated for field applications. The sensitivity on the orientation for a free-fall atom gravimeter is investigated in this paper. The apparatus is simplified and improved a lot such that fast adjustment and measurement could be carried out within 20 minutes. From the experimental results, it is found that the orientation angle has a dominant influence on the absolute gravity measurement, especially when the horizontal velocity of atoms is non-negligible. Besides, the magnitude and direction of average horizontal velocity of the detected atoms are obtained in this experiment. In particular, the direction of East–West has been measured by the atom gravimeter itself, such that gravity bias arising from Coriolis effect is estimated precisely.

Shipborne atomic gravimeter (SAG) is an instrument that can directly measure absolute gravity in dynamic environments. As a new type of gravity sensor, a standard method for evaluating its detailed performance has not been proposed and the detailed performance of SAG was rarely reported. In this paper, a system of dynamic gravity measurement, which was integrated with a home-made atomic gravimeter, is demonstrated, and a novel and simple method for testing the performance of SAG on the lake based on the modulated Coriolis effect is put forward. Firstly, in the state of ship mooring, a tilt modulation of the gravity sensor has been realized to make sure the Raman wave vector is parallel to the gravity axis. Moreover, a comparison between the measurement result of CG-5 and SAG has also been carried out to evaluate the accuracy of the SAG. Then, the Coriolis effect modulating experiment is carried out with various routes on lake to test its performance in dynamic environments. In the ship mooring state, the accuracy has been demonstrated to be 0.643 mGal. The internal consistency reliabilities are evaluated to be 0.8 mGal and 1.2 mGal under the conditions of straight line and circle navigation, respectively.

Currently, most of the experimental apparatuses of atomic gravimeters are complex in structure, large in size, and poor in environmental adaptability, so that they cannot be used to implement the absolute gravity measurement. Thus, the application areas of atomic gravimeter are greatly limited. In this paper, we integrate a system of absolute gravity measurement on a truck based on a compact homemade atomic gravimeter. This atomic gravimeter has a small size, light weight, low power consumption, and its accuracy is estimated as 10 μGal in the case of laboratory environment. This system consists of atomic gravimeter for gravity measurement, passive isolation platform for vibration suppression, posture platform for tilt adjustment, differential GPS for altitude measurement, UPS for power supply, air-conditioned truck for temperature control and transportation. At first, we estimate the performance of environmental adaptability for this measurement system on the truck, and it is found that this system can still work even at a high field temperature of 40 ℃ and a big tilt angle of 8° for the road. Besides, the experimental procedures of absolute gravity measurement and the methods of processing measured data are introduced. The Coriolis effect is analyzed and the dependence of measured gravity on the orientation of the truck has been measured. Finally, the repeated line measurements are performed on a flat field road. The accuracy of self-coincidence for absolute gravity measurement is evaluated to be 30 μGal and the difference in measured gravity among different locations is about 3080 μGal. Besides, we obtain the vertical gravity gradient of the earth by measuring the absolute gravity values at different altitude sites on a slope road, and the value is estimated to be －231(36) μGal/m. The presented results can provide the basic reference for the field absolute gravity survey.

Cold atomic gravimeters are attracting more and more attention and activity in the area of gravity measurement and comparison, and the corresponding methods for measurement and traceability need to be explored. Based on two self-developed cold atomic gravimeters, research on the comparison and traceability methods of absolute gravity measurement was carried out. The entire gravity measurement traceability process is divided into two stages: the preliminary traceability in the laboratory and the formal traceability in the absolute gravity reference station. Through comparison of two atomic gravimeters (ZAG-E and ZAG-B) in the laboratory, the degree of equivalence D D and the normalized deviation E n of ZAG-E are obtained, which are − 2.7 ± 7.6 µ G a l ( k = 2 ) and − 0.3599 , respectively. Relative to the absolute gravity reference at the National Institute of Metrology (NIM) in China, D D and E n of ZAG-E are 0.5 ± 12.0 µ G a l ( k = 2 ) and 0.0417, respectively. | E n | ≤ 1 in the two traceability stages, so the results of two traceability stages are acceptable, which indicates the consistency of the comparisons is good. Finally, the absolute gravity measurement value of ZAG-E is traced to the SI units, ensuring its accuracy. A gravity traceability method for atomic gravimeters is given and is very beneficial for the applications of atomic gravimeters in metrology and other fields.