Response of RadFET dosimeters to high fluences of fast neutrons

Radiation Monitoring in Mixed Environments at CERN: From the IRRAD6 Facility to the LHC Experiments

“…For doses exceeding 10 Gy their response curve becomes strongly sub-linear, i.e., begins to saturate. Although the responses of all MOSFETs under "zero bias" are always strongly sub-linear [10], the REM devices at the same total dose are not saturating in this way. The saturation mechanism is not well understood but it is clear that further electron escape might be retarded by built-in oxide fields due to oxide-trapped positive charge [31].…”

“…It has been shown [10], [32] that the distribution and composition of the materials around RadFETs can strongly interfere with TID measurements, especially in radiation fields containing neutrons and/or low energy photons. Dose enhancement effects are thus an issue.…”

“…It is thus clear that the sensors for the LHC have to cover different sensitivities and a broad dynamic range in terms of TID and particle fluence as well as to comply with specific stability [8], [9] and response [10] requirements. For all these reasons, after intensive test campaigns, a series of four devices (two RadFETs and two p-i-n diodes) has been proved to fulfill LHC Experiments needs [11].…”

Packaging Effects on RadFET Sensors for High Energy Physics Experiments

“…Only few experimental works have been reported on this topic. For example, the increase of the dose measured with RadFETs exposed to fast neutrons and covered with Polyethylene slabs of different thicknesses was investigated in [10]. RadFETs exposed to a Co-60 source and to monoenergetic low energy protons, covered or not covered by a lid were investigated in [11].…”

“…At intermediate energies (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) GeV) the Parameterized models, originally derived from GHEISHA [37], were activated. The highest energy range (20 GeV-100 TeV) was covered by the Quark Gluon String model [39].…”