The Beam Charge Monitor - Bergoz Instrumentation - #1

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To monitor injection efficiency on boosters and storage rings On transfer lines or linacs, measures single pulses with 1 pC resolution On continuous beams up to 10 MHz, measures the stored beam current with <10nA resolution. The Beam Charge Monitor (BCM) measures pulsed beams. Its bipolar voltage output is directly proportional to the beam charge. An Integrating Current Transformer (ICT) integrates the charge of pulses having width from less than a picosecond to more than a microsecond. A builtin Calibration Generator provides on-line assurance of measurement reliability. Two versions are available: • Integrate-Hold-Reset (BCM-IHR), for pulse repetition rates from 10 kHz down to single pulses, • Continuous Averaging (BCM-CA), for pulse repetition rates from 10 MHz down to 5 kHz. “Integrate-Hold-Reset” version Operating principle: The signal from the Integrating Current Transformer (ICT) is amplified by a Charge Amplifier, and passed to the Beam Signal Processor. Before each pulse, a user’s-supplied trigger determines the beginning of a measurement cycle: the signal baseline is clamped, then it is integrated by two integrators in synchronous detection mode, thus rejecting the background noise very effectively. The integrating capacitors are fully discharged after each pulse integration. The output voltage proportional to the beam pulse is available 30 ìs after the trigger. It is maintained up to 400ìs (adjustable), then reset. Another pulse can then be measured. Integrate-Hold-Reset, Operating range Using the most sensitive ICT : • Full scale is ±400 pC for ± 7 V output • Noise is 700. With minimum gain and ICT with 50:1 turns ratio • Full scale is ±400 nC for ±7 Volts output • Noise is 100'000 With the Low-noise Wideband Amplifier (BCM-WBA) option: • Full scale range down to 200 ìA for 10V output • Noise 20'000 BCMBeam Charge Monitor Bunch charge integration with highest accuracy BCM-RFC 19” chassis, partial view, equipped with 5 BCM modules