Measurement, direct mass

Process industries frequently need to weigh and control the flow rate of bulk material for optimum performance of such devices as grinders or pulverizers, or for controlling additives, eg, to water suppHes. A scale can be installed in a belt conveyor, or a short belt feeder can be mounted on a platform scale. Either can be equipped with controls to maintain the feed rate within limits by controlling the operation of the device feeding the material to the conveyor. Direct mass measurement with a nuclear scale can also be used to measure and control such a continuous stream of material. 

Direct Mass Measurement One type of densitometer measures the natural vibration frequency and relates the amplitude to changes in density. The density sensor is a U-shaped tube held stationaiy at its node points and allowed to vibrate at its natural frequency. At the curved end of the U is an electrochemical device that periodically strikes the tube. At the other end of the U, the fluid is continuously passed through the tube. Between strikes, the tube vibrates at its natural frequency. The frequency changes directly in proportion to changes in density. A pickup device at the cui ved end of the U measures the frequency and electronically determines the fluid density. This technique is usefiil because it is not affec ted by the optical properties of the fluid. However, particulate matter in the process fluid can affect the accuracy. 

USING THE ISOLDE-3 MASS SEPARATOR The high resolution of ISOLDE 3 (design value = 3.10 ) enables direct mass measurements. Such measurements were proposed at the Workshop "On-line in 1984 and beyond" held at Zinal [ZIN84]. In these experiments, the transmission signals have to be split in order to obtain the necessary accuracy. However, the feasibility of this technique has already been demonstrated by the Chalk River group [SHA84]. 

We expect direct mass measurements to form an important component of the exotic-nuclei program at TASCC. Indeed, we already hope to upgrade our facilities through a proposal made in collaboration with the University of Manitoba to build a high-transmission mass spectrometer, which could accept beam from the ISOL directly without reionization, again making use of the ISOL s excellent beam quality. This could improve the precision of measurements to a level rivalling that now possible with stable isotopes. 

Time-of-Flight Isochronous Spectrometer for Direct Mass Measurements of Exotic Light Nuclei... 

Direct mass measurements on unstable nuclides with ultra-high accuracy (up to Sm/m PS 10 ) will also be possible. Such an accuracy would allow one to determine the binding energy of with an accuracy of 2 eV. If the... 

A high-precision mass measurement system with Penning traps, SHIPTRAP (Block et al. 2007) at GSI has been developed to investigate nuclear structure of rare isotopes far from stability. The direct mass measurements of have been successfiiUy performed (Block... 

Weber, C. Towards direct mass measurements of nobelium at SHIPTRAP. Eur. Phys. J. D 45, 39 5 (2007)... 

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