CASCADE BM-2D 32 and BM-2D 100
Position sensitive beam monitoring in various sizes may be employed to precisely quantify the neutron intensity delivered to the sample. The BM-2D monitors comprise a converter layer of customized Boron thickness and a GEM based amplification stage. They are read out through a 64 channel pre-amplifier and digitizing readout ASIC that serves to identify the position of conversion through coincidence in X- and Y- signal pairs. The monitors may be seamlessly integrated into the CDT provided DAQ-systems that are based upon CDR, CDRS and CDRE readout boards.
Typical pixelization ranges from 1 to 3 mm. Maximum rate capability on the monitor area is 1 MHz at 10% dead time.
The monitors may not be operated in vacuum. A 10 mm vaccum gap with vacuum windows needs to be supplied for the monitor to slide in for an in-beam operation.
The Ionization-Chamber-Beammonitor I-BM is a beam monitor for thermal neutrons thought as an extremely robust beam monitoring solution for extreme environments of radiation exposure and thus very limited accessibility. The device, the front-end chamber itself, needs no servicing over its lifetime. It is composed as an entirely passive device without exposed gain stage or requirements concerning operation gas or other consumables. The beam monitor is designed as an ionization chamber with ambient air as gas filling and a natural Boron coating to give it sensitivity to thermal neutrons. In the environment of application the device is, apart from neutrons, typically exposed to very high gamma dose rates. To increase the devices specificity, it is designed as an ionization chamber pair with a measurement cell and a reference cell, the former being coated with a neutron converter, the latter being uncoated and serving as a gamma dose reference in a difference measurement.
The ionization chamber provides an additional advantage over counting neutron detectors that is key for chopper signal monitoring: As there is no limitation in neutron conversion rate, the ionization beam monitor may be customized for signal responsivity and fast neutron pulses. In comparison, counting neutron detectors have an individual neutron pulse duration on the order of a few 100 ns. If a signal rise is of interest, only a few 10 counts may be registered within 10 µs resulting in very limited amplitude resolution. This statistical variation may be avoided entirely using an ionization chamber, where an ionization current is observed.