SET-UP OF DIGITAL MCA WITH HPGE DETECTOR IN HIGH GAMMA FIELDS

摘要

The processing time adjustability of a commercial portable spectroscopy workstation based on Digital Signal Processing technology was investigated in areas from highly contaminated (mSv/h dose rate) to high energies (up to 8 MeV) to throughput and resolution performance coaxial Germanium detector. Altering the rise/fall and flat top times of the trapezoidal filter, it was estimated the full width at half maximum at the following peaks: ~(54)Mn 834.8 keV, ~(60)Co 1332.5 keV, ~(16)O(n, p)~(16)N 6129.9 keV, ~(56)Fe(n, γ) 7631.1 keV and ~(56)Fe(n, γ) 7645.5 keV. First type measurement for ultra-high counting and throughput rates was performed at ionex filter which capture activation products (~(54)Mn, ~(60)Co) from primary cooling medium and second type measurement for highest resolution was carried out at pressure water reactor platform during nominal power level giving high energy gamma 6129.9 keV from interaction fast neutrons ~(16)O(n, p)~(16)N and 7631.1 keV, 7645.5 keV from radiation capturing thermal neutrons by ~(56)Fe(n, γ). To measure through energy range up to 8 MeV was reached setting coarse and fine gain to lower range and measuring at contaminated ionex filter by GBq activity was allowed using 50 mm cylindrical collimator by 30 mm diameter, without using this collimator was destroyed whole gamma spectrum despite altering rise/flat times. The results, which are presented, provide optimum performance for high throughput: FWHM 1.71 keV/834.8 keV (~(54)Mn) and 2.00 keV/1332.5 keV (~(60)Co) and best resolution: FWHM 4.49 keV/6129.9 keV (~(16)N), 4.97 keV/7631.1 keV/7645.5 keV (prompt gamma iron) setting 2.8 μs rise time and 0.6 μs flat top time. For 0.8/1.2 μs rise time and 0.2 μs flat top time occurred results with destroyed resolution broadening and peak shift at 6129.9 keV and 7631.1/7645.5 keV. For rise time above 8.8 μs and flat time above 0.8 μs were peaks at 834.8 keV and 1332.5 keV unusable for purpose peak analysis process.