Thermal neutron self-shielding correction factors for large sample instrumental neutron activation analysis using the MCNP code

Tzika

2007

Annali di Chimica

Large sample neutron activation analysis compliments and significantly extends the analytical tools available for cultural heritage and authentication studies providing unique applications of non-destructive, multi-element analysis of materials that are too precious to damage for sampling purposes, representative sampling of heterogeneous materials or even analysis of whole objects. In this work, correction factors for neutron self-shielding, gamma-ray attenuation and volume distribution of the activity in large volume samples composed of iron and ceramic material were derived. Moreover, the effect of inhomogeneity on the accuracy of the technique was examined.

Section: Inhomogeneity Considerationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Large Sample Neutron Activation Analysis: A Challenge in Cultural Heritage Studies

Tzika

2007

Annali di Chimica

“…In LSNAA the sample is irradiated at a research reactor (using a graphite thermal neutron column or a radial channel) and is subsequently transferred to a gamma ray spectrometry system to be counted either as a whole [1] or using a scanning geometry counting configuration [2]. Corrections are required for self-shielding of the activating neutrons, self-absorption of gamma rays, heterogeneity of the sample and geometric factor during gamma counting [3][4][5][6][7][8]. Analysis of the acquired gamma spectra allows for the evaluation of the elemental composition of the sample.…”

Section: Introductionmentioning

confidence: 99%

Large sample neutron activation analysis of irregular-shaped pottery artifacts

Vasilopoulou

Montoya³

et al. 2014

J Radioanal Nucl Chem

The large sample neutron activation analysis (LSNAA) method developed at NCSR ''Demokritos'' for large and irregular-shaped objects was applied for the analysis of a Peruvian pottery artifact with the shape of an animal. The correction factors required for neutron selfshielding and gamma-ray self-attenuation within the sample material were derived through Monte Carlo simulations using the MCNP code, based on an accurate model obtained by computerized tomography X-ray scanning. The LSNAA results were compared with those from conventional instrumental neutron activation analysis (INAA) and a very good agreement was observed.

“…Corrections are required for self-shielding of the activating neutrons [5,6], self-absorption of gamma rays [7], heterogeneity of the sample [8,9] and geometric factor during gamma counting [10]. Moreover, k 0 based calibration techniques for LSNAA have been presented [11,12].…”

Section: Introductionmentioning

confidence: 99%

Large sample neutron activation analysis of a ceramic vase

Tzika

Vasilopoulou

et al. 2010

J Radioanal Nucl Chem

Self Cite

Large Sample Neutron Activation Analysis (LSNAA) was applied to perform non-destructive elemental analysis of a ceramic vase. Appropriate neutron self-shielding and gamma ray detection efficiency calibration factors were derived using Monte Carlo code MCNP5. The results of LSNAA were compared against Instrumental Neutron Activation Analysis (INAA) results and a satisfactory agreement between the two methods was observed. The ratio of derived concentrations between the two methods was within 0.7 and 1.3. Estimation of the activity level decay with time showed that the vase could be released from regulatory control at about 3 months postirradiation. This study provided an analytical procedure for bulk sample analysis of precious and archaeological objects that need to be preserved intact and cannot be damaged for sampling purposes.