An EPICS module that supports quad electrometers/picoammeters, typically used for photodiode-based x-ray beam position monitors, or split ion chambers. They can also be used for any low-current measurement that requires high speed digital input. There is support for two models:
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The TetrAMM picoammeter from CAENels. This device communicates using TCP/IP over 1 Gbit/s Ethernet. It provides 4-channel current measurements at up to 20000 Hz.
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The AH401B, AH401D, AH501, AH501C, and AH501D picoammeters originally designed Synchrotron Trieste (elettra) They are now sold commercially by CAENels. These devices communicate using TCP/IP over 100 Mbit/s Ethernet or high-speed serial. They provide 4-channel current measurements at up to 1000 Hz (AH401 series) or 6510 Hz (AH501 series).
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The Quad Electrometer built by Steve Ross from the APS (called APS_EM in this document). This device consists of a 4-channel digital electrometer unit and 2 VME boards. The device provides 2 readings per diode at up to 813 Hz.
Additional information: