Instruments and Methods Design, optimization and calibration of an automated densitygauge for firn and ice cores

摘要

A gamma-ray density gauge can provide high-resolution and high-precision densitymeasurements of firn and ice cores. This study describes the design, gamma-ray energy optimization andmass attenuation coefficient calibration of the Maine Automated Density Gauge Experiment (MADGE),a portable, field-operable gamma-ray density gauge used on overland traverses in East Antarctica. TheMADGE instrument uses a 241 Am gamma-ray source, a pulse-mode counting system and electronic corediameter calipers to collect high-precision (±0.004 g cm-3) density data from 3-8 cm diameter firn andice cores. The data are collected at a 3.3 mm spatial resolution and an average throughput of 1.5 m 11-1for 5 cm diameter cores.