Particle Geiger-Muller counter

The emission from the radioisotopes is often insufficient to penetrate the window of a Geiger-Muller counter. Therefore, the compound whose activity is to be measured is often mixed in solution with a scintillator, called a fluor, which transforms / rays into luminescence proportional to the number of /3 particles emitted. The sample is dissolved in a solvent (toluene, xylene or dioxane, the latter being used for water-soluble compounds) that acts as a relay to transfer the energy to the scintillator. The scintillation mixture contains PPO (2,5-diphenyloxazole), which emits in the UV and POPOP, which emits in the visible and is well adapted to detection with photomultiplier tubes (Fig. 17.2). The quantum yield of emission will depend on the energy of the emitted particles. 

Alpha-particle detector Beta-particle detector Gamma-ray detector proportional counters silicon (Si) diode with spectrometer proportional counters Geiger-Muller counters liquid scintillation (LS) counters thallium-activated sodium iodide (Nal(Tl) detector with spectrometer germanium (Ge) detector with spectrometer... 

A schematic representation of a Geiger-Muller counter. The high-energy radioactive particle enters the window and ionizes argon atoms along its path. The resulting ions and electrons produce a momentary current pulse, which is amplified and counted. 

Geiger-Muller counter (Geiger counter) an instrument that measures the rate of radioactive decay by registering the ions and electrons produced as a radioactive particle passes through a gas-filled chamber. 

The attempts to separate our artificial radium isotopes from barium in this way were unsuccessful, Hahn would explain in his Nobel Prize lecture no enrichment of the radium was obtained. It was natural to ascribe this lack of success to the exceptionally low intensity of our preparations. It was always a question of merely a few thousands of atoms, which could only be detected as individual particles by the Geiger-Muller counter. Such a small number of atoms could be carried away by the great excess of inactive barium without any increase or decrease being perceptible. To check that possibility they retrieved from storage a known radium isotope they often worked with, the isotope they called mesothorium. They diluted it to match the pale radioactivity of their few thousand atoms of Ra-III, then ran it through barium precipitation and fractionation. It separated away cleanly from the barium. Their technique was not at fault. 

A schematic representation of a Geiger-Muller counter. The high-speed particle knocks electrons off argon atoms to form ions. 

Zinc-71 decays by beta emission, and has a half-life of 2.4 minutes. Suppose a 0.200-g sample of Zn-71 was put inside the tube of a Geiger-Muller counter that counted every beta particle emitted by the sample for 2.4 minutes. What would the... 

Radioactivity can be instantly detected with devices such as the Geigeiv Muller counter ( Figure 17.7b). In such an instrument (commonly referred to simply as a Geiger counter), parhcles emitted by radioactive nuclei pass through an argon-filled chamber. The energehc particles create a trail of ionized argon... 

The Geiger counter, invented in 1928 and named after one of its two inventors, H. Geiger and E.W. Muller, counts particles emitted by radioactive nuclei in a non-reactive noble gas, like argon. Alpha and beta particles are detected this way. 

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