**6. Applications in industry and daily life**

As many particle detectors, HPGe detectors are now also used for other purposes than fundamental research. HPGe detectors can now be found in different industries such as environment control, medical imaging, and of course radioactive material control.

One of the most common uses of HPGe is the monitoring of atmospheric radiations. Stations around the world check the air quality and collect air content samples or solid samples, such as rocks, water, or plants. The samples are then analyzed in a laboratory. Thanks to their excellent resolution and low background once placed in a suitable environment, and the radio-elements contained in the samples can be determined. It is, for example, possible to detect radio-elements with concentrations down to 0.1–1 Bq/kg in solids and 0.1 Bq/L in water. The system can be improved by adding scintillator array around the germanium detectors to eliminate signals from cosmic rays. Such system is, for example, used to obtain a sensitivity of millibecquerels per cubic meter of an air sample.

Another practical example of use of HPGe to study radioactivity of liquids can be found in the study of old wines. Take a 1928 vintage bottle of Bordeaux wine; its cost can approach \$10,000. However, how sure is the buyer that this bottle is really from 1928? To check this, the bottle was placed in an array of germanium detectors. The analysis immediately showed that the bottle contained traces of Cs137. Cs137 is a radioactive element presents in the atmosphere due to nuclear bombs…, which means that it cannot be found in a bottle of 1928. The quantification of Cs137 is now used to date wine produced after 1950 without opening the bottle.

So far, HPGe detectors for medical purposes were mainly used for nuclear waste control produced by hospital. Here, the procedure is the same than for any nuclear waste collected from a nuclear power plant for example. The contaminated volume is placed near the detector. The analysis of the spectrum will reveal radioactive elements present and their quantity. The cost and mechanical constraints related to the use of liquid nitrogen limited the deployment of HPGe in hospitals for medical imaging. However, novel imaging methods, combining HPGe and silicon detectors are envisioned for future scanners such as ProSPECTus. Such system could reduce the dose to the patient, improve image quality, and be faster to acquire.

The list of industrial applications of HPGe will become longer as we progress toward more reliable, easier to use, and cheaper detectors. Originally only pushed by fundamental research, the development of new HPGe is now also driven by the needs of companies using them. New applications, not yet considered, will then emerge.

#### **7. Conclusions**

The future of HPGe detectors depends on the availability of other materials that would match the resolution performance of HPGe at 77 K, while operating at room temperature. Segmentation of the detectors provides a way to reduce carrier collection lengths and hence to mitigate the effects of electrically active deep defects. With integrated microelectronics, the noise can be as low as a few tens of electrons. With on detectors CMOS chips and low capacitance detectors, the electronic noise can be reduced to less than 100 e-h pairs. With ε equal to 4.5 eV (GaAs, CdTe), this corresponds to a resolution of the order of 450 eV. This could also be applied to HPGe detectors that are being used for double beta decay or dark matter experiments. The multielectrode scheme that is implemented in EDELWEISS III [46] is a first step toward a time-projection chamber HPGe detector, allowing an improved

**79**

**Author details**

Nicolas Fourches2

provided the original work is properly cited.

\*, Magdalena Zielińska2

1 Institut de Physique Nucleaire d'Orsay, Orsay Cedex, France

2 Universite Paris-Saclay, CEA/IRFU, Gif/Yvette Cedex, France

\*Address all correspondence to: nicolas.fourches@cea.fr

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

and Gabriel Charles1

*High Purity Germanium: From Gamma-Ray Detection to Dark Matter Subterranean Detectors*

discrimination ability. Each electrode could be a separate channel, which would be easy for the detector operated at low field and low voltage. It seems clear that the use in more routine applications such as, for instance, high-precision radioactive material characterization and radioactive material tracing to avoid nuclear dissemination will remain a field where HPGe is the most competitive despite the need for LN2 cryogenic installations. Development of cryogenic cooling fridges will eliminate this specific constraint. In scientific applications, HPGe, being one of the

The contribution of researchers from IRFU and other institutions, with whom the first author had fruitful discussions while working on dark matter instrumenta-

chemically purest materials ever fabricated, will remain needed.

The authors declare having no conflict of interest.

*DOI: http://dx.doi.org/10.5772/intechopen.82864*

**Acknowledgements**

**Conflict of interest**

tion, is gratefully acknowledged.

*High Purity Germanium: From Gamma-Ray Detection to Dark Matter Subterranean Detectors DOI: http://dx.doi.org/10.5772/intechopen.82864*

discrimination ability. Each electrode could be a separate channel, which would be easy for the detector operated at low field and low voltage. It seems clear that the use in more routine applications such as, for instance, high-precision radioactive material characterization and radioactive material tracing to avoid nuclear dissemination will remain a field where HPGe is the most competitive despite the need for LN2 cryogenic installations. Development of cryogenic cooling fridges will eliminate this specific constraint. In scientific applications, HPGe, being one of the chemically purest materials ever fabricated, will remain needed.
