The sensitivity of probe depends on the used tungsten collimator. The basic sensitivity is determined by the standard collimator (40°). The sensitivity is shown in the figure - it's depending on the distance between lymph-node and probe tip. Tungsten articulatable hand-held probe’s sensitivity > 20,000 counts/s/MBq.

By increasing the dihedral angle the tungsten articulatable hand-held probe’s sensitivity increases significantly, while the spatial resolution gets worse.

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There are many ways for synthesis tungsten oxytetrafluoride, generally including the following four: the first method is through tungsten hexafluoride (WF6) primary hydrolysis to obtain tungsten oxytetrafluoride(WOF4);the second is using tungsten oxytetrachloride(WOCl4) react with hydrogen fluoride; third is through tungsten hexafluoride (WF6) react with tungsten trioxide to produce tungsten oxytetrafluoride; the fourth is after frit reaction between  tungsten trioxide and lithium fluoride to obtain tungsten oxytetrafluoride. Here introduce two ways for produce tungsten oxytetrafluoride which is the most widely used and processes are relatively simple.
(1) Put the fluorine gas into reactor where has tungsten trioxide powder with 230-400℃, after the reaction the gaseous WOF4 will be expelled from the reaction vessel, and condense in trap where the trap is heated to 130 ℃.
(2) First, mixing fluorine and oxygen, wherein the molar ratio is F2: O2 = 3: 1. Then pass into the tungsten powder, after reaction there will generate WOF4 also produce a small amount of tungsten hexafluoride. But tungsten hexafluoride is a volatile substance, so it can be got rid of at room temperature by vacuum method. Finally, use vacuum sublimation to produce WOF4 which is more pure.

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In order to study the solid-phase reduction process of CaWO₄ and Si at low temperature during steelmaking process by direct alloying,the thermo-analysis experiments on CaWO₄ and Si powder mixture have been carried out by using differential thermal analyzer with constant heating rate 10℃/min,the reaction products and reaction ratio of CaWO₄ and Si pellets at 1 400℃for 30 min are analyzed by high temperature furnace constant temperature test and combined with melting point measure test the behavior of physical change of pellets in heating process is analyzed.Experimental results show that the reduction reactions of CaWO₄ and Si occurred at less than 1 400℃are all solid-phase reaction,the products of reaction are W, WSi₂, W₅Si₃, Ca3(Si₃O₉) and SiO₂,the reduction ratio of CaWO₄ pellets at 1400℃for 30 min is up to 93.41%,and during solid-phase reaction process the CaO could not increase the reaction rate;with condition of constant heating rate at less than 1 400℃,the apparent reaction of CaWO₄ and Si conforms to Avarami-Erofeev equation,the mechanism of reaction is random nucleation and subsequent growth,and the apparent reaction dynamical equation is da/dt = 11.68e～(-51.75×10～3/RT)·4(1-α)[-ln(1-α)]～(3/4).

 

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Tungsten can react with fluorine gas, which is tungsten powder react with fluorine gas should at 200 ℃, but  fine powder at room temperature can be reacted with fluorine gas. Besides tungsten rod needs at 300 ℃ can it react with the fluorine .
Tungsten tetrafluoride is a white monoclinic crystalline, CAS registry number: 13520-79-1. Its physical properties are as follows: chemical formula: WOF4, molecular weight: 275.9, melting point: 110 ℃, boiling point: 185 ℃, vapor pressure (P unit is mmHg, 1mmHg = 133.322Pa, T to K): 105-186 ℃ lgP = 9.69-3125 / T, 50 -104 ℃ lgP = 10.96-3605 / T. Besides, it is easily hydrolysis and deliquescence, in moist air the color will turn yellow, and generate hydrofluoric acid, but insoluble in tungsten tetrachloride. Meanwhile tungsten oxytetrafluoride and tungsten hexafluoride having similar strong reactivity can react with organic compound and metal chlorides. But when compared to tungsten hexafluoride found tungsten oxytetrafluoride has more stable reactivity. 

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