Figure 1: Stand Monitor.
Stand_3cm“Stand 3cm” detector comprise of four-layer assembly of 3 cm thick 1 m2 sensitive area molded plastic scintillators one above the other.
Tuning of Stand 3cm was made by means of the 8-channel signal analyzer developed at ASEC for online data processing. Proper tuning of the detector provides 98–99% signal detection efﬁciency simultaneously suppressing electronic noise down to 1–2%. The data acquisition (DAQ) electronics measures and stores all coincidences of the signal appearance in the detector channels. Coincidence ‘’1000’’ corresponds to signal registration only from upper scintillator, ‘‘1100’’ – from the ﬁrst two upper scintillators, and so on. GEANT4 simulations demonstrate that Stand 3cm detector can measure count rate of incident electrons with energy thresholds 5, 15, 25, 35 MeV (combinations ‘‘1000’’, ‘‘1100’’, ‘‘1110’’ and ‘‘1111’’). The 5 MeV electrons can give signal above the discrimination level only in the upper scintillator, to be absorbed then in the scintillator body, or in the metallic tilts of scintillator housing; the 15 MeV electrons can penetrate and be registered also in the second scintillator, and so on. In this way, measuring the enhancements of count rates of above mentioned 4 combinations of detector layer operation we can recover the integral energy spectra of TGE electrons, of course, after subtracting the gamma ray contamination.
The electronics signal threshold of Stand 3cm detector is ~3 MeV, thus, all 4 Stand 3cm layers can detect gamma rays with energies greater than ~3 MeV, although with much smaller registration efﬁciencies comparing with electron detection efﬁciencies. Gamma rays should have high enough energy to create high- energy charged particles, which can reach bottom layer (the gamma ray energy should be above 40 MeV to generate signal in all 4 layers with probability 1%).