In this study, the validity of the effective (virtual) point-detector concept for the CdZnTe (CZT) detector for disc-shaped
radioisotope sources has been investigated in the photon energy range of 50–662 keV. It has been found that the virtual point-detector
model is valid for conventional CZT detectors. The photon energy dependence of the virtual interaction depth (VID) in the
CZT detector does not seem to fit to a good trend. However, in general, the measured VID values are increasing with increasing
γ-ray energy in the range of 50–662 keV, but the VID values always remain within the physical thickness of the CZT detector.
For instance, the VID value was measured to be about 4.4±0.5 mm in the 5 mm thick CZT detector at 662 keV γ-ray energy. In
application, the VID values for photons can be used for efficiency calculation models by scaling the measured detection efficiency
as a function of energy and source-to-detector distance.
Variation of virtual point detector (VPD) position inside HPGe detector as a function of source photon energy for the energy
range from 26.6 to 1,332 keV was investigated. Although VPD concept was well established for HPGe detectors from 59.5 to 10 MeV,
a new attempt was made to obtain VPD positions for photon energies below 59.5 keV. It was found that VPD position shows different
functional behavior for the energy ranges 26.6–59.5 keV and 59.5–1,332 keV. The VPD position decreases with increasing energy
for 26.6, 31.7, 36.4, and 37.3 keV and increases with the energy until it reaches a plateau. The functional behavior of VPD
position for the energy range 26.6–59.5 keV was attributed to the dead layer thickness of the Ge crystal. Monte Carlo simulations
were performed to investigate the behavior of VPD position with various dead layer thickness ranging from 100 to 800 μm. It
was seen that VPD position increases with increasing energy for 31.7, 59.5, and 80.1 keV more significant at relatively lower
energies, but constant for the energies 661–1,332 keV.
Authors:Linping Zhang, Xianlei Song, Yanyan Song, Zhanbo Sun, Qian Li, Xiaoping Song, and Liqun Wang
, the enthalpy difference of the solid phase transformation from non-equilibrium to equilibrium states at T cannot be obtained directly. Therefore, a virtual isothermal transformation from non-equilibrium to equilibrium could be designed at T
The assessment of the statistical counting uncertainty is discussed for two pulse loss correction methods in nuclear spectrometry: the 'loss-free counting' technique based on the virtual pulse generator method and the 'zero dead time' technique with 'variance spectrum'.
High rate, high resolution gamma-spectrometry with real-time correction of counting losses is made possible by combining the novel Preloaded Filter (PLF) pulse processor with the Virtual Pulse Generator (VPG) counting loss correction method. A spectrometry system for high-speed activation analysis based on the PLF processor, VPG correction and a high resolution LOAX detector is tested up to 850 kc/s.
Authors:Z. B. Alfassi, F. Groppi, M. L. Bonardi, O. Presler, and U. German
The paper deals with the common mistake of interpolating calculation of the efficiency of gamma-detectors by the inverse square
law of the distance of the source from the detector cap and suggests the use of the distance from the virtual point detector
Authors:L. Fucugauchi, S. Millán, A. Mondragón, and M. Solache-Ríos
The chemical effects of98Mo(n, )99 Mo reaction on molybdenum(II) chloride [(Mo6Cl8)Cl4] have been studied. Retention, thermal and radiolytical annealing were determined. It was found that this molybdenum compound has low retention, a negligible tendency to thermal annealing and a virtual insensitivity to hydrolysis. For practical application in the enrichment of99Mo by the Shilard-Chalmers method, molybdenum(II) chloride [(Mo6Cl8)Cl4] appears to offer good prospects.
Authors:A. Mukherjee, S. Kamila, and V. Chakravortty
Extraction studies of uranium(VI) by the binary mixture of PC88A and benzimidazole show an antagonistic behavior in the concentration
range 10−5–10−6M of PC88A and 0.005M of benzimidazole. Antagonism is observed due to the deprotonation of PC88A by benzimidazole forming
an adduct resulting in the virtual removal of PC88A from the system.
Authors:R. Presler, O. Presler, U. German, and Z. Alfassi
The concept of representing a cylindrical detector volume as a virtual point detector in order to simplify the evaluation
of the detector efficiency was proposed in the past for HPGe detectors in the case of measuring point sources. In the present
work, the validity of the point detector model was studied and confirmed for the direct measurement of small volume sources,
when using a common 7.5×7.5 cm2 NaI(T1) detector.