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MEASARminus for use of individual CEMs with negative high voltage


MEASARminus is a modular electronic instrument to operate systems with multiple channel electron multipliers (CEMs) or photomultipliers (PMTs) and evaluate all output signals simultaneously by pulse counting as well as current and integral charge measurements.

It consists of a mechanical housing in 19"-subrack technology, with a module high voltage generation, pulse counting, current and charge monitoring, and one system controller module with an RS 232-interface, which may easily be translated to USB by means of an external bridging circuit, to connect the system to a host computer. The computer sets the high voltage, discriminator threshold, and measurement time. Measurements can be run by start command or automatically repeated.


High Voltage
- 128 to - 4095
HV slope (1 bit)
±100 or ±800
Preamplifier threshold
- 3 to - 130.5, step size = 0.5
Preamplifier deadtime
15 - 30 - 60 - 100
Measurement time interval
unlimited, stop by command, or
(1 to 65535) x 10
  Measurement repetitions
unlimited, stop by command, or
1 to 255 automatically repeated
CEM overload protection
max. anode current (1-15) x 1.024
  Current measuring
full scale = 16.38375
  Charge accumulation
up to 335.54 µC
  Anode bias
- 120 (±10)







Fig. 3 MEASARminus for the simultaneous use of several CEMs and negative applied high voltage



















Fig. 1 MEASARminus for use of five CEMs with negative high voltage (ion mode)
Fig. 2 Multiple collector array from the ThermoFisher NEPTUNE and TRITON isotope mass spectrometer
Thermo Fisher (Bremen) GmbH






















































Dr. Sjuts Optotechnik GmbH

Am Schlehdorn 1, 37077 Goettingen, Germany Tel. + 49 (0) 551 209 95 62, Fax. + 49 (0) 551 209 95 63