Superintense laser-driven photon activation analysis

Laser-driven radiation sources are attracting increasing attention for several materials science applications. While laser-driven ions, electrons and neutrons have already been considered to carry out the elemental characterization of materials, the possibility to exploit high-energy photons remains unexplored. Indeed, the electrons generated by the interaction of an ultra-intense laser pulse with a near-critical material can be turned into high-energy photons via bremsstrahlung emission when shot into a high-Z converter. These photons could be effectively exploited to perform Photon Activation Analysis (PAA). In the present work, laser-driven PAA is proposed and investigated. We develop a theoretical approach to identify the optimal experimental conditions for laser-driven PAA in a wide range of laser intensities. Lastly, exploiting the Monte Carlo and Particle-In-Cell tools, we successfully simulate PAA experiments performed with both conventional accelerators and laser-driven sources. Under high repetition rate operation (i.e. 1−10 Hz) conditions, the ultra-intense lasers can allow performing PAA with performances comparable with those achieved with conventional accelerators. Moreover, laser-driven PAA could be exploited jointly with complementary laser-driven materials characterization techniques under investigation in existing laser facilities.

Instrumental Photon Activation Analysis with Short-Time Irradiation for Geochemical Research

This paper introduces instrumental photon activation analysis (IPAA) utilizing short-lived products of photonuclear reactions, mainly (γ, n) and (γ, p), initiated by bremsstrahlung from the MT-25 microtron. A rapid nondestructive IPAA method for geochemical major element analysis is introduced as a tool for the basic geochemical characterization of rocks. Procedures were developed and parameters such as beam energy and irradiation-decay-counting times optimized with a representative set of geochemical reference materials, and an optimized scheme was applied in analysis of various geological samples. A complete analytical scheme combined with long-time irradiation IPAA and the possibility of utilization of photoexcitation reactions (γ, γ′) are briefly outlined.

Kilogram Sample Analysis by Nuclear Analytical Techniques: Complementary Opportunities for the Mineral and Geosciences

Sample-size reduction including homogenization is often required to obtain a test portion for element compositional analysis. Analyses of replicate test portions may provide insight into the sampling constant, and often much larger quantities are needed to limit the contribution of sampling error. In addition, it cannot be demonstrated that the finally obtained test portion is truly representative of the originally collected material. Nuclear analytical techniques such as neutron and photon activation analysis and (neutron-induced) prompt gamma activation analyses can now be used to study and overcome these analytical problems. These techniques are capable of obtaining multi-element measurements from irregularly shaped objects with masses ranging from multiple grams to multiple kilograms. Prompt gamma analysis can be combined with neutron tomography, resulting in position-sensitive information. The analysis of large samples provides unprecedented complementary opportunities for the mineral and geosciences. It enables the experimental assessment of the representativeness of test portions of the originally collected material, as well as the analysis of samples that are not allowed to be sub-sampled or dissolved, the analysis of materials that are difficult to be homogenized at large, and studies on the location of inhomogeneities. Examples of such applications of large-sample analyses are described herein.

Photon activation analysis of metallurgical tap smelting slag using a high energy medical accelerator: Further studies

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Improved calibration for non destructive determination of manganese in metallurgical tap smelting slag using a high energy medical accelerator

An improved calibration method for the non-destructive determination of the manganese content in large metallurgical tap smelting slag samples using photon activation analysis is presented. A metallurgical tap smelting slag of archaeological interest from the Psaphaki site, Laconia, was irradiated under the mixed photon and parasitic neutron field produced by an 18 MV medical accelerator. The sample was 236 g in mass. Manganese was determined by the photon and neutron induced reactions 55Mn(g, n)54Mn and 55Mn(n,g)56Mn, measuring the 834.8 keV 54Mn and 846.8 keV 56Mn photopeaks, respectively. Gamma spectra from the large sample and calibration foils were acquired using a HPGe detector of 85% relative efficiency. The Efficiency Transfer method was applied to determine the Full Energy Peak Efficiency (FEPE) of the large sample. The results of the analysis showed that the manganese content in the slag was (39.5±15.8) % w/w and (39.7±2.6) % w/w measuring the 56Mn photopeak and the 54Mn photopeak, respectively. Therefore, a good agreement between the photon and neutron activation analysis techniques was observed. Advantages of the technique include improved representativeness of results, elimination of reference samples, irradiation versatility and convenience, as well as reduced contamination probability since a minimal sample preparation was required for the analysis. Moreover, the introduction of the relative calibration technique removes the dependency on parameters that are usually evaluated with larger uncertainties, such as detector efficiency, increasing the quality and reliability of the procedure.

Photon activation analysis of sand samples from Antalya in Turkey with a clinical electron linear accelerator

The purpose of this study is to demonstrate the feasibility of elemental analysis of sand samples by photon activation induced by high energy bremsstrahlung photons at an end point energy of 18 MeV from a clinical electron linear accelerator. The γ-ray spectra of the activated samples were collected using a high resolution spectrometer. Qualitative analysis of major and trace components of the samples (12 in total) was carried out whilst the spectra of eight of the samples were evaluated quantitatively. The contents of elements obtained by photon activation analysis were compared with values obtained by X-ray fluorescence.