Research Vessel

For the missions in Egypt, “Princess Duda” serves as the base for the team and equipment. During the mission, the boat is securely anchored on six concrete moorings, just above the main excavation site. During the missions usually 30 people sleep on board. The boat is equipped with a compressor for filling the diving tanks, a crane to hoist discoveries on board and a spacious deck where the archaeological material is housed and initial conservation can be done. For pinpoint excavations or soundings, the team uses several motorized fishing boats.

Anomalies

The techniques of geophysical analysis consist of revealing the discontinuities of the parameters measured, such as the ambient magnetic field and the acoustic response of various terrains. These discontinuities or contrasts are called ‘anomalies’.

In archaeological terms the range of interesting anomalies is very limited. The sensors also pick up numerous naturally occurring geological features, which show up as anomalies. The discovery of remains depends on correctly differentiating between these two kinds of anomalies.

The success of this relies on both technology, and on the judgement of trained professionals. It comes down to the sensitivity of the sensors, and the expertise with which they are implemented; on the computer processing of the measurements, and on the analysis of the results.

NMR Magnetometer

Nuclear Magnetic Resonance (NMR) Magnetometers are the principal sensors in our surveying system. These highly sensitive sensors were developed by the French Atomic Energy Commission (CEA). Based on simultaneous proton and electron magnetic resonance (the Abragam-Overhauser effect), the NMR magnetometers measure the absolute value of the earth’s magnetic field more than one thousand times per second - with an accuracy of one fifty-millionth of its value.

MRM-2000 Frequency-meter

A specialized frequency-meter delivers the absolute value of the magnetic field with an accuracy of one thousandth of a Gamma, which means an accuracy of a frequency measurement to the seventh decimal place (10 puissance -7Hz).

A high integrated version of a this frequency-meter, named MRM-2000 has been developed by the engineering team of Franck Goddio in collaboration with the French Atomic Energy Commission.

Geomagnetism

The earth's magnetic field superimposes very complex temporal and spatial phenomena - the earth's crust geology, dynamo effect, sun-earth interaction, ionospheric and telluric currents, etc. - involving magnetic and electric properties. The earth's magnetic field can be schematically considered as bipolar and of a value between 20000 nano Tesla (nT) on the equator and 60000 nT at the poles, in addition to which there exists a field of global anomalies (of about 10000 nT), a field of geological local anomalies and temporary phenomena of some tens of nT every day.

Application to Archaeology

The magnetic anomalies created by archaeological remains are superimposed on the anomalies of natural origin. The ability to differentiate between these anomalies is based on the extreme sensitivity of our magnetometers and, where necessary, on the measurement of the local magnetic gradient between two sensors towed simultaneously. This gradient meter reduces the temporal variations of the earth’s magnetic field and enables us to dismiss a great many of the geological anomalies. This method, implemented using NMR magnetometers, permits the detection of objects with very weak magnetism, even when they are buried deep under layers of sediment.