Nuclear radiation sensors

When detecting the interface between two liquids, electrical conductivity, thermal conductivity, opacity, or sonic transmittance of the liquids can be used. Interface-level switches are usually of the sonic, optical, capacitance, displacer, conductivity, thermal, microwave, or radiation types. Differential pressure transmitters can continuously detect the interface, but, if their density differential is small relative to the span, the error will be high. On clean services, float- and displacer-type sensors can also be used as interface-level detectors. In specialized cases, such as the continuous detection of the interface between the ash and coal layers in fluidized bed combustion chambers, the best choice is to use the nuclear radiation sensors. 

An expensive method is the use of nuclear radiation to obtain information on the level in an apparatus. The nuclear sensor is mounted at one side, and at the other side a scintillation counter is fixed near the surface of the apparatus. Both systems are sheathed with lead-screen shields to give protection from nuclear radiation. A continous level indicator using nuclear radiation is very complicated and therfeore seldom applied. 

Silicon semiconductor detectors for nuclear radiation monitors of neutron rays have been developed by Kitaguchi et al. (1995,1996). These are diffused p-n junction-type devices with low leakage current coated on the surface of the B-containing sensor element. Neutrons were detected as recoil protons by interaction of the proton radiator and a-particles generated by the nuclear reaction °B (n, a) Li. The energy response of this radiation detector meets the standard recommendations and is suited as an area monitor and a personal dosimeter as well. 

The terms detector, transducer, and sensor are often used synonymously, but in fact the terms have somewhat different meanings. The most general of the three terms, detector, refers to a mechanical, electrical, or chemical device that identifies, records, or indicates a change in one of the variables in its environment, such as pressure, temperature, electrical charge, electromagnetic radiation, nuclear radiation, particulates, or molecules. This term has become a catchall to the e.x-tent that entire instruments are often referred to as detectors. In the conte.vt of instrumental analysis, we shall use the term detector in the general sense in which we have just defined it. and we shall use detection system to refer to entire assemblies that indicate or record physical or chemicalquantities. An example is the UV(ultra-... 

B.C. Passenheim, C.E. Mallon Nuclear radiation vulnerability of ring laser gyroscope , SPIE Vol. 157 Laser Inertial Rotation Sensors, 205-211 (1978)... 

By using NFS, information on both rotational and translational dynamics can be extracted. In many cases, it would be favorable to obtain separate information about either rotational or translational mobility of the sensor molecule. In this respect, two other nuclear scattering techniques using synchrotron radiation are of advantage. Synchrotron radiation-based perturbed angular correlations (SRPAC) yields direct and quantitative evidence for rotational dynamics (see Sect. 9.8). NIS monitors the relative influence of intra- and inter-molecular forces via the vibrational density of states (DOS) which can be influenced by the onset of molecular rotation (see Sect. 9.9.5). 

The use of TRDs has been facilitated by the use of fibre-optic cable assemblies (Section 6.12.4). This permits sensing in confined spaces as well as enabling the sensor to see round corners and into regions containing nuclear or electromagnetic radiation 36 . Low levels of source visibility can be overcome by employing two-colour or ratio sensors which measure radiation at two different wavelengths simultaneously. Such instruments can be used where dust or dirt obscures the source from the sensor. 

All the detectors used are usually developed specifically for the needs of nuclear testing. In the French test gamma radiation was analysed by Compton and Cerenkov detectors. X-ray spectrometry required photoelectric detectors and optical axes under vacuum. Neutrons were analysed by optical sensors and reverse proton telescopes. 

A short description of possible nuclear applications of boron-based materials had been done by Potapov (1961) in an old overview that included the nuclear power industry (e.g., control rods of nuclear reactors) solid-state electronics (e.g., counters of neutrons and neutron energy sensors) radiation chemistry (e.g., acceleration of technological processes) etc. For these purposes, "B nuclei are useless, but °B nuclei are useful due to a large cross section of interaction with thermal neutrons, °B converts them into heavy ionizing particles. Besides, °B isotope is applicable for neutron radiation protection (Stantso 1983) and also in medicine, e.g., in boron neutron capture therapy (BNCT) for treating cancer tumors (Desson 2007). 

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