Background radiation noise

The choice of a detector for a specific appHcation should be made in order to minimize the cooling requirements and the magnitude of the background radiation noise therefore, in detector selection the cutoff wavelength should be only slightly greater than that required by the appHcation. If the... 

Different analytical techniques are used for detection of the elemental composition of the solid samples. The simplest is direct detection of emission from the plasma of the ablated material formed above a sample surface. This technique is generally referred to as LIBS or LIPS (laser induced breakdown/plasma spectroscopy). Strong continuous background radiation from the hot plasma plume does not enable detection of atomic and ionic lines of specific elements during the first few hundred nanoseconds of plasma evolution. One can achieve a reasonable signal-to-noise ra-... 

In summary, pulse-height analysis (PHA) prior to a Mossbauer measurement is an essential step in tuning a Mossbauer spectrometer. PHA allows the adjustment of the y-detection system to the Mossbauer photons and the reduction of noise by rejecting nonresonant background radiation. 

One method used to isolate a X-ray line from unwanted background and noise, employs equilibrated filters. It consists of linking the concentration of interest to the difference between two measurements. The first is obtained by installing a transmission filter between the sample and the detector to isolate the characteristic radiation of the element wanted and the second by fitting an absorption filter which is opaque to this same radiation. This will enable, for example, to quantify the copper from its main spectral line by using two filters, one made of nickel and the other made of cobalt. The fluorescence originating from the filters themselves is a limiting factor in this method, which is reserved for routine measurements. 

It may be useful to keep in mind that this is a rather unusual example, because very few other analytical measurements would have noise levels such that they would allow the determination of a second component with an amplitude of less than 0.5% of that of the major signal. In that respect, radiochemical measurements are rather unique, because quanta released in radioactive decay have such high energies that individual disintegrations can be counted, in counts that are often virtually free of electronic noise. Apart from the inherent randomness of radioactive disintegrations (see section 2.10), the only noise in such measurements is background radiation, which usually can be kept extremely low by careful shielding. 

Radiation source flicker Flame background emission noise... 

The calculations in the previous subsection assumed that the noise in the detector arose from fluctuations in the generation rate of carriers corresponding to fluctuations in the background radiation arriving at the detector from a... 

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