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Prompt gamma neutron activation analysis (PGNAA) is frequently used in on–line analysis of raw materials in cement and coal industries which normally incorporates bismuth germanate (BGO) or sodium iodide (NaI(Tl)) scintillators. The quantitative results are basically undertaken through full–spectrum analysis method which requires an efficient noise reduction procedure to optimize PGNAA data. Here in this study, the empirical mode decomposition (EMD) technique has been used to reduce the noise level of PGNAA spectra of a neutron–irradiated NaCl·H 2 O solution and then the results have been compared with those of wavelet technique. The mean square errors (MSEs) comparisons confirm that both EMD and wavelet techniques can be efficiently used for noise reduction purposes, however, this study recommends the EMD technique for its independency of basic functions, simplicity and spectrum data-based operation. [ABSTRACT FROM AUTHOR]

The appropriate gamma-ray detector shielding configuration is critical for a precise prompt gamma neutron activation analysis (PGNAA) measurement. The shielding material has to prevent the radiation damage to the detector crystal and it must produce less activation gamma rays, whether prompt or delayed, which may interfere the gamma ray spectrum of the sample. In this research, using common shielding materials, a number of combinations have been studies to form a 50 cm long shield for portable PGNAA system against both fast and slow neutrons as well as gamma rays emitted by 20Ci Am–Be source. The measurement results show that in contrast with conventional shadow cone in which the shielding material starts with 20 cm heavy metals such as iron and ends with 30 cm polymer materials, in portable PGNAA systems, the shielding material gives better results if it starts with about 40 cm borated polymer material and ends with an appropriate thickness (7 cm to 10 cm) of heavy metal such as tungsten. [ABSTRACT FROM AUTHOR]

In this research, based on pulse reconstruction method, digital storage oscilloscopes with an 8-bit digital-to-analog convertor was used to successfully perform the neutron-gamma discrimination with NE213 (or its equivalent BC501A) scintillator anode pulses at minimum discrimination bias value of 95 keVee (or keV electron equivalent). Also, a 100 mCi 241 Am–Be source and micro-Curie gamma ray sources ( 137 Cs and 22 Na) were used for the system calibration and discrimination studies. The results confirm the feasibility and simplicity of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: Scintillation of the photomultiplier glass window and its effects on the detector response were studied. It was proved that effects could have a considerable contribution to the pulse-height spectrum, especially when low-efficiency scintillators were used. [Copyright &y& Elsevier]

Abstract: The neutron-gamma discrimination capability of the new-type UGLLT liquid scintillator has been compared with NE213 (or its Bicron equivalent, BC501A). An Am-Be combined neutron-gamma isotopic source and a zero-crossing circuitry were used to explore various biases resulting the optimum figure of merits (FOMs) of 1.52 and 1.18 for NE213 and UGLLT at 170keVee bias, respectively. The study shows that the UGLLT scintillator can be a good alternative for NE213 in pulse-shape discrimination experiments. [Copyright &y& Elsevier]

In this paper, a digital neutron–gamma discrimination (DNGD) method with an NE213 scintillator has been proposed in which the anode pulse is divided into two different pulses, one representing the amplitude and the other characterizes the DNGD. Then the two pulses are summed up after travelling through delay and mixer circuits to form an input pulse for sampling in analog–to–digital converter (ADC). The discrimination tests have been performed with an 8–bit digital storage oscilloscope (DSO) as ADC and 241 Am–Be neutron source, whereas the Fourier method has been used to derive the discrimination characteristic. The results confirm the fast performance and efficiency of proposed method. [ABSTRACT FROM AUTHOR]

Abstract: A 5cm diameter by 6cm height NE213 scintillator attached to two XP2282 PHOTONIS photomultiplier tubes (PMTs) exposed to 241Americium–Berylium (Am–Be) neutron–gamma source has been used for timing response studies. The neutron–gamma discrimination (NGD) measurements based on a modified zero-crossing (ZC) method show that the discrimination quality, usually expressed in figure-of-merit (FoM) and peak-to-valley (P/V) values, has been improved. The timing response evaluated with Monte Carlo light transport code, PHOTRACK, also verifies this improvement. [Copyright &y& Elsevier]

Abstract: In this paper, using zero-crossing method, the neutron–gamma discrimination has been discussed to estimate the contribution of light transport on the timing characteristics of scintillation detectors. Both experimental and simulation verifications for the influence of lightguide length on the neutron–gamma discrimination quality of a 2×2 in. NE213 scintillator have been presented. [Copyright &y& Elsevier]

Liquid organic scintillators are widely used in radiation measurements. NE213 (or its equivalent, BC-501A) in neutron-gamma discrimination (NGD) and two new scintillators, UGLLT and UGAB, in alpha-beta discrimination are two common examples. In this paper, the NGD capabilities of these three scintillators were studied and their figure-of-merits (FoMs) were measured for comparison. The three different NGD methods used in this study were zero-cross method (ZCM), charge integration method (CIM) and filtered charge integration method (FCIM), where ZCM was analog and the two other methods were digital. A 1.1 μCi point 22Na gamma ray source and 100 mCi cylindrical 241Am–Be neutron source (3.5 cm diameter by 5 cm length) were used for the energy calibration and the NGD, respectively. The FoM values for NE213, UGLLT and UGAB at 100 keVee discrimination bias (i.e. , the preset threshold voltage, generally expressed in keVee unit, upon which the generated pulse-heights are recorded) using ZCM, CIM and FCIM methods were (1.060 ± 0.037, 1.430 ± 0.040, 1.70 ± 0.054), (0.910 ± 0.029, 1.270 ± 0.018, 1.460 ± 0.027) and (0.890 ± 0.027, 1.200 ± 0.020, 1.460 ± 0.026), respectively. Although UGAB scintillator exhibits the least discrimination quality, one can choose an appropriate neutron-gamma discrimination method to improve its FoM. The low-temperature flammability, toxicity and high-evaporation properties of NE213 scintillator may motivate some researchers to use UGLLT and UGAB scintillators as alternatives to NE213, however, by selecting the most efficient discrimination method. [ABSTRACT FROM AUTHOR]

In this study, a digital neutron-gamma discrimination (DNGD) has been performed based on the pulse-shape discrimination on the anode pulse of a 2″ by 2″ right cylinder BC501A liquid scintillator with a fast data acquisition card (14-bit resolution, 500 Mega-samples per second (MS/s)) using the charge integral method. Different pulse-processing parameters for the DNGD and their corresponding figure-of-merits (FoMs) have been studied. In addition, the FoM dependencies on different pulse-processing parameters have been determined. A 100 mCi 241Am-Be neutron source has been used for the DNGD and the calibration has been made with a 1.1 mCi 22 Na gamma-ray source. The results show that a more efficient DNGD (with 25 % improved discrimination quality) can be performed on the anode pulse of the BC501A scintillator by optimizing the pulse-processing parameters. • Digital neutron-gamma discrimination (DNGD) was performed with liquid scintillator. • Output pulse of the detector was sampled with 14-bit resolution, 500 MS/s digitizer. • Software DONGE was developed to perform different processions on digitizer data. • Optimum parameters behavior was studied for different DNGD measurement conditions. • Neutron spectrum unfolding with FORIST code confirmed the DNGD quality of DONGE. [ABSTRACT FROM AUTHOR]