Speaker
Martin Klein
(Univ. Heidelberg)
Description
The modular CASCADE detector system is designed for high intensity neutron applications with high demands on the dynamical range, contrast as well as background. The system is based on a conceptually innovative detector front-end paired with strategic transfer of modern technology from the fields of highly integrated readout electronics.
The detector front-end is a hybrid, solid converter gas detector, which has proven its high rate capability also in other fields as the high-energy physics. In the CASCADE detector, several Gas Electron Multiplier (GEM) foils, invented from Sauli at CERN, are employed as charge transparent substrates to carry solid 10B layers. These coated GEMs are then stacked one behind the other to cumulate the detection efficiency of every layer without spoiling position information. The charges generated by the fragmentation products in the gas spacing between successive GEMs are channelled through the GEMs to a readout structure. The last GEM foil is operated with gain in order to raise signals comfortably above the noise level of electronics. The use of GEM-foils allows high count rates up to 107 n/cm2 s. The use of 10B allows detector operation with ordinary counting gases under normal pressure. The well-defined neutron absorption locus inside the thin boron layer provides sub microsecond absolute time resolution, which opens the door towards new TOF applications. Because 96% isotopically enriched boron is available in large quantities and for a reasonable price in contrast to 3He, 10B-converter based neutron detector technology is one of the very few technological alternatives to 3He in view of the imminent crisis in world-wide supply of 3He.
The neutron detection bottleneck shifts to data read-out electronics and its bandwidth. Highly integrated ASIC-technology allows to realize thousands of individual detection channels at non-proportional cost. The CASCADE detector design uses an ASIC electronic front-end paired with an adaptable integrated FPGA data processing unit to provide high rate capacity and online event reconstruction. Furthermore the FPGA’s firmware manages the onboard memory to realize freely configurable histogram counters. These data counters allow to effectively histogram and thus compress neutron data to a level, where exclusively user relevant information remains. But also list-mode can be taken and read out as one possible configuration.
Applications of this detector for thermal, cold and ultra-cold neutrons will be shown.
