| 摘要 |
An apparatus for measuring the basis weight of a web-shaped material under test comprises a radioactive beta radiation source on one side of the material under test and a beta radiation detector on the other side of the material under test. For focusing the electrons emitted by the radioactive beta radiation source, a magnetic field is provided, such that for the same source activity, significantly more beta particle intensity is available on the material under test for measuring the transmission.
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