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Multi-channel analyser (MCA)
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A stream of linear pulses, usually unipolar, leaves the amplifier. The final electronic problem is to sort these according to their pulse height, the pulse height being proportional to the gamma ray energy deposited in the detector. This is done using a single channel analyser. Two voltage levels are set up, the lower level discriminator (LLD), H1, and the upper level discriminator (ULD), H2.Such a device would give an output pulse for every input pulse whose maximum falls into the voltage slot or window of H2 - H1.

A multi-channel analyser is made of banks of single-channel analysers where the ULD of one window is the LLD of the next.

On the next page, there is an active simulation of an MCA. 


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1999, 2000 The University of Liverpool, Department of Physics

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