Scintillator high efficiency

Scintillators are also used in the detectors of CT scanners. Here an electronic detector, the photomultiplier tube, is used to produce an electrical signal from the visible and ultraviolet light photons. These imaging systems typically need fast scintillators with a high efficiency. 

Dacheux N, Aupiais J (1997) Determination of uranium, thorium, plutonium, americium, and curium ultratraces by photon electron rejecting alpha liquid scintillation. Anal Chem 69 2275-2282 Duan YX, Chamberlin EP, Olivares JA (1997) Development of a new high-efficiency thermal ionization source for mass spectrometry. Inti JMass Spectrom IonProcessesl61 27-39 Edwards RL, Chen JH, Wasserburg GJ (1987) systematics and the precise... 

Fig. 2 Schematic diagram of a hydrogen depth profiling setup using a high efficiency BGO detector. A cooled sample holder is placed close to the front surface of the BGO scintillator in ultra-high vacuum. The sample holder can be moved perpendicular to the plane of the figure to bring different samples into the 15N beam and is surrounded by a Faraday cup arrangement to ensure accurate measurement of the analyzing beam dose.

Liquid scintillation counters are highly efficient for low CL intensities and consist of two photon-counting channels provided with a variable discriminator. The sample is placed between these two detectors to ensure a high optical efficiency. The discriminator is adjusted to allow photon impacts to be transmitted and small background noise pulses to be rejected. As disadvantages they suffer from saturation errors and provide nonlinear relationships between the CL intensity and the total counts. 

Unfortunately the counting efficiency of the system was relatively poor, 0.2% for tritium and 17% for carbon. However, the advantage of this method is that due to the cell being packed with beads, it would have little flow resistance and limited peak dispersion and thus if used in conjunction with suitable low dispersion connecting tubes, it could be used with relatively high efficiency columns. As a consequence, many modem commercial radioactivity detectors are designed on the same principle, but with more efficient scintillators and more efficiently designed sensors. 

LIQUID SCINTILLATION COUNTING OF INORGANIC RADIOCHEMICALS IN HIGH-EFFICIENCY SCINTILLATORS... 

Most of our work with transition metal radionuclides has been with Fe and Ni. The former decays by electron capture, for which the highest energy x-ray is 5.5 keV (Gibson and Marshall, 1972). The Ni is a low-energy beta-particle emitter (Eg maximum of 55.87 keV). To prepare very high-efficiency scintillators for these two radionuclides, one... 

The development of the high-efficiency scintillator shown in Table IV for is described in Hutchinson et al. 

HIGH EFFICIENCY GAMMA RADIATION DETECTION IN CLINICAL RADIOIMMUNOASSAYS BY LIQUID SCINTILLATION COUNTING WITH "LSC GAMMA VIALS"... 

Commercially available, highly efficient liquid and solid scintillators were tested as standards for comparison with our samples. Ultima Gold (PerkinElmer) is a standard liquid scintillation counting cocktail, containing PPO (ca. 1 wt %) in a mixture of aromatic compounds, and phosphate and succinate surfactants. BC-400 (Bicron) is a plastic scintillator composed of organic fluors, PPO and POPOP, at <3 wt % in PVT. KG2 (Bicron) is a cerium-activated lithium silicate glass scintillator, containing 7.5 wt % of Li (95% i) as a neutron absorber, and Ce as a scintillation material. 

PPO and POPOP are among the most commonly used organic primary and secondary fluors, respectively. Despite their high efficiencies in both liquid and plastic scintillators, one limitation is their incompatibility with hydrophilic reagents. In liquid scintillation techniques, an efficient extraction of radioactive nuclides into the organic phase where PPO and POPOP dissolve is often mandatory. In neutron detection by plastic scintillators, the use of an efficient, yet hydrophilic, neutron absorber, Li, is strictly limited if not prohibited. 

Lao.9oCeo.ioP04 nanocrystals were surface modified with mixed surfactants a mixture of DDA and BEHP or a mixture of OA and BEHP. The surface modified nanocrystals were dispersed at SO wt % in polystyrene, forming translucent thick films on quartz discs. Pulse height spectra from alpha particle detection (Source Am) of nanocrystal samples superimposed with the result from a highly efficient plastic scintillator, BC-400 are presented in Figure 3. 

Many efforts have been focused on the development of new scintillation films with highly efficient registration of different particles, high-time and energy resolutions, resistance to radiation damage, high signal-to-noise ratio and low cost. Astvatsaturov et al. reported the synthesis of... 

Samples were often divided into many groups to enable detection with Nal(Tl) scintillators that had relatively low resolution but high efficiency. The separation scheme was based on the application of a set of columns filled with selective or semi-selective sorption materials that retained certain groups of elements. In the ideal case, the same load solution was passed through consecutively joined columns, thus offering a chance for automation of the procedure. 

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