小型超電導重力計

抄録

Three important problems exist in constructing a superconducting gravimeter. These are (1) to keep liquid helium as long as possible, (2) to make the sensor mass astatic, and (3) to use a high sensitivity detector to measure small variation of position of the sensor mass. A superconducting gravimeter with a diameter of 15 mm is designed and set up in liquid helium storage tank of 50 liters. This device will be used for gravity measure ment continuously for more than a month. The smallest vertical force gradient of the device which we have used corresponds to a resonant frequency of 2 Hz of the sensor mass. Variation of position of the sensor mass will be detected with the sensitivity of 1 Angström (10^-8 cm) by use of a superconducting quantum interference device(SQUID). By use of this device it is expected that gravity variations can be measured with a sensi tivity better than 10^-9 G.