Author/Authors :
Croci، نويسنده , , G. and Claps، نويسنده , , G. and Cavenago، نويسنده , , M. and Dalla Palma، نويسنده , , Diana M. and Grosso، نويسنده , , G. and Murtas، نويسنده , , F. and Pasqualotto، نويسنده , , R. and Perelli Cippo، نويسنده , , E. and Pietropaolo، نويسنده , , A. and Rebai، نويسنده , , M. and Tardocchi، نويسنده , , M. and Tollin، نويسنده , , M. and Gorini، نويسنده , , G.، نويسنده ,
Abstract :
Fast neutron detectors with a sub-millimetric space resolution are required in order to qualify neutron beams in applications related to magnetically-controlled nuclear fusion plasmas and to spallation sources. A nGEM detector has been developed for the CNESM diagnostic system of the SPIDER NBI prototype for ITER and as beam monitor for fast neutrons lines at spallation sources. The nGEM is a triple GEM gaseous detector equipped with polypropylene and polyethylene layers used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the results obtained by testing a nGEM detector at the ISIS spallation source on the VESUVIO beam line. Beam profiles (σx=14.35 mm, σy=15.75 mm), nGEM counting efficiency (around 10-4 for 3 MeV<En<15 MeV), detector stability (≈4.5%) and the effect of filtering the beam with different type of materials were successfully measured. The x beam profile was compared to the one measured by a single crystal diamond detector. Finally, the efficiency of the detector was simulated exploiting the GEANT4 tool.
Keywords :
GEM (Gas electron multiplier) , fast neutrons , efficiency , SIMULATION
