A geothermal probe, comprising a main probe, which at least comprises: - a main probe heat medium circuit and a feeder probe medium circuit, - an evaporation chamber (2.1), which comprises a refrigerant chamber (4.1) of a counterflow evaporator and a closed refrigerant circuit, whereby the closed refrigerant circuit is filled with ammonia, i.e. NH 3, as the refrigerant, - a riser (2.2), which is connected to the lower end (2.21) of the evaporation chamber (2.1), - a supply pipe (2.5), which is connected to the evaporation chamber (2.1) and is arranged in the refrigerant circuit, - a heat exchanger chamber (2.3), which comprises at least one heat medium chamber (4.2) of the counterflow evaporator and is arranged in a maln probe heat medium circuit of a heating medium, whereby the geothermal probe additionally has a feeder probe, which comprises at least: - an outer jacket (3.1), which is enclosed on its outside by the soil when the geothermal probe is In operation, - a probe gap (3.2), which is at least partially bounded by the inside of the outer jacket (3.1) and a probe bottom (3.3), in which the main probe is arranged, and - at least one inlet (7.1), for the fluid heat medium, which is arranged In at least one open feeder probe heat medium circuit, whereby the counterflow evaporator has at least one refrigerant chamber (4.1) and at least one heat medium chamber (4.2) and the geothermal probe has a measurement and control device, which is integrated into the process control system to provide a continuous gaseous refrigerant flow, and whereby the counterflow evaporator is a three stage counterflow evaporator, which comprises three segments of similar design connected in series so that the evaporator chamber (2.1) comprises three sections arranged in series and whereby the feeder probe is a catch basin for the refrigerant escaping from the main probe. - a main probe heat medium circuit and a feeder probe medium circuit, - an evaporation chamber (2.1), which comprises a refrigerant chamber (4.1) of a counterflow evaporator and a closed refrigerant circuit, whereby the closed refrigerant circuit is filled with ammonia, i.e. NH 3, as the refrigerant, - a riser (2.2), which is connected to the lower end (2.21) of the evaporation chamber (2.1), - a supply pipe (2.5), which is connected to the evaporation chamber (2.1) and is arranged in the refrigerant circuit, - a heat exchanger chamber (2.3), which comprises at least one heat medium chamber (4.2) of the counterflow evaporator and is arranged in a maln probe heat medium circuit of a heating medium, whereby the geothermal probe additionally has a feeder probe, which comprises at least: - an outer jacket (3.1), which is enclosed on its outside by the soil when the geothermal probe is In operation, - a probe gap (3.2), which is at least partially bounded by the inside of the outer jacket (3.1) and a probe bottom (3.3), in which the main probe is arranged, and - at least one inlet (7.1), for the fluid heat medium, which is arranged In at least one open feeder probe heat medium circuit, whereby the counterflow evaporator has at least one refrigerant chamber (4.1) and at least one heat medium chamber (4.2) and the geothermal probe has a measurement and control device, which is integrated into the process control system to provide a continuous gaseous refrigerant flow, and whereby the counterflow evaporator is a three stage counterflow evaporator, which comprises three segments of similar design connected in series so that the evaporator chamber (2.1) comprises three sections arranged in series and whereby the feeder probe is a catch basin for the refrigerant escaping from the main probe.