Gamma tracer distribution

In preparation for a PET scan, a patient is injected with a dose of the tracer, which quickly accumulates in the brain. The patient is placed inside the PET scanner, and the instrument detects the gamma rays emitted by the tracer. The result is an image showing the distribution of glucose in the brain, which indicates where brain activity is greatest. 

A tracer test on a packed vessel with "closed ends" gave the data of the first two columns of the table. Find conversion of a second order reaction with kC0 - 2 in segregated flow (a) with the direct data (b) with a Gamma distribution of the same variance. 

Gamma-ray, X-ray, optical and infrared line spectroscopy of SNe and SNRs have been used to observe nucleosynthesis and the abundance distribution of elements freshly synthesized (both radioactive isotopes and stable decay products) and to extract dynamical information about the explosion. In particular the radioactive isotopes provide unique tracers of nucleosynthetic processes (what, where and how much) and its related dynamics. The best examples are the observations of gamma-ray lines in supernovae, but X-ray line spectroscopy of decay products of radioactive nuclei have also been attempted, and specific elements in numerous SNRs and a few SNe identified. 

A monotonic relationship between intensity (i.e., count rate) and distance between the tracer and each detector was established by calibration. The density dependence of gamma ray attenuation through the bed made it necessary to calibrate in situ because of the inhomogeneity of the bubbling fluidized bed. The procedure involved positioning the tracer in a large number of distributed locations within the bed and then measuring the count rates of all detectors at each tracer location. 

Methods The measurements were carried out by batch equilibration, most by an isotope dilution technique. Samples of clay were pre-equilibrated several times with NaCl-CaCl2 solutions of fixed compositions, until successive equilibrations showed no change in concentration. To separate samples (separate because of he difficulty of discriminating between the gamma emission of Na and Ca radioisotopes) were added known amounts of Na and Ca tracers, and the solutions were allowed to equilibrate for 2-5 days. The solid was centrifuged down, and aliquots of the supernatant solutions were counted. By material balance, the fractions of the activity adsorbed were computed, and, from these, the distribution coefficients, D... 

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