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Synopsis: High Purity Germanium (HPGe) is the only radiation detection technology that provides sufficient information to accurately and reliably identify radionuclides from their passive gamma ray emissions. HPGe detectors have a 20-30x improvement in resolution as compared to that of Sodium Iodide (NaI) detectors.
What are germanium detectors used for?
Germanium detectors are mostly used for gamma spectroscopy in nuclear physics, as well as x-ray spectroscopy.
How does a germanium detector work?
Ionizing radiation enters the sensitive volume (germanium crystal) of the detector and interacts with the semiconductor material. High-energy photon passing through the detector ionizes the atoms of semiconductor, producing the electron-hole pairs.
What kind of detector is the best to use for gamma radiation?
Silicon detectors are most heavily used in charged-particle spectroscopy and are also used for Compton- recoil spectroscopy of high-energy gamma rays. Other solid-state detection media besides germanium and silicon have been applied to gamma-ray spectroscopy.
How germanium detectors are different from Si Li detector?
intensity is much larger in Ge detectors, compared with Si detectors, due to the higher x-ray fluorescence yield and larger linear absorption coefficients for Ge [6]. This represents a fundamental limitation to the use of Ge detectors in the analysis of complex x-ray spectra in the energy region above 11.1 keV.
Why are germanium detectors cooled?
Germanium detectors must be cooled to reduce this leakage current to the point where the associated noise does not degrade the energy resolution. Normally, HPGe detectors are cooled with liquid nitrogen (LN2) to 85- 105 K inside a specially-designed cryostat.
What are silicon detectors used for?
Silicon detectors are widely used in experiments in particle physics. The application of this detector technology is mostly for tracking detectors, i.e. detectors which measure the position of charged particles. From this information, track reconstruction software from the experiments deduces many parameters.
What are gamma rays wavelength?
Gamma rays have frequencies greater than about 10^19 cycles per second, or hertz (Hz), and wavelengths of less than 100 picometers (pm), or 4 x 10^9 inches. (A picometer is one-trillionth of a meter.)
What is used to detect gamma rays?
The thallium-activated sodium iodide detector, or NaI(Tl) detector, responds to the gamma ray by producing a small flash of light, or a scintillation. The scintillation occurs when scintillator electrons, excited by the energy of the photon, return to their ground state.
Why are Si and Ge used in making solid state detectors?
The advantages of germanium over silicon for this application are improved signal to noise ratio and energy resolution and the capability of detecting photons up to 100 keV with reasonable efficiency even with small volume devices.
