Zsuzsa Hajnal

Bio: Zsuzsa Hajnal is an academic researcher from Hungarian National Museum. The author has contributed to research in topics: Neutron & Spallation Neutron Source. The author has an hindex of 3, co-authored 4 publications receiving 75 citations.

Imaging of cultural heritage objects using neutron resonances

Abstract: Neutron resonances are the signature signals of a non-destructive elemental and isotopic analysis technique in archaeological sciences. We report on Neutron Resonance Transmission Analysis and its capabilities as a bulk elemental imaging technique to test the homogeneity of samples and to localize elements of interest in archaeological samples and museum objects. A high neutron flux is required for imaging in order to achieve reasonable spatial resolution and to keep measurement times within realistic limits. A modular system for neutron resonance transmission analysis has been designed and installed at the INES beamline of the ISIS spallation neutron source as a part of the ANCIENT CHARM project. The main component is a neutron position sensitive transmission detector which is based on a 10 × 10 array of 6Li-glass crystals mounted on a pitch of 2.5 mm, resulting in a 25 × 25 mm2 active area. Transmission spectra are obtained by a measurement of the flight time of epithermal neutrons passing through an object. The transmission dips observed in a time-of-flight spectrum can be used to identify and quantify specific nuclides. In this paper the technique is described together with the data reduction and analysis procedures. In addition, preliminary results obtained from measurements on cultural heritage samples are discussed.

The ANCIENT CHARM project at FRM II: three-dimensional elemental mapping by prompt gamma activation imaging and neutron tomography

Abstract: The aim of the EU FP6-funded ANCIENT CHARM project has been the development of new, and the integration of existing element-sensitive imaging methods utilizing neutrons. We present here the methodology and the first implementation of 3D elemental mapping at the Prompt Gamma Activation Analysis instrument of the research reactor FRM II, in order to determine spatially resolved elemental abundances in samples. After the design, optimization, and characterization of the new setup, measurements were successfully completed on archaeological objects of historical significance from the collection of the Hungarian National Museum.

Neutron resonance transmission imaging for 3D elemental mapping at the ISIS spallation neutron source

Abstract: We demonstrate for the first time the viability of a three-dimensional (3D) elemental imaging technique based on Neutron Resonance Transmission Imaging (NRTI), which is a neutron technique based on the presence of a resonance structure in the neutron-induced reaction cross sections. These resonances allow the identification of elements and isotopes within an object in a non-destructive manner. A dedicated set-up on the INES (Italian Neutron Experimental Station) beamline of the ISIS spallation neutron source was employed for the experiments. An early mediaeval disc fibula from the Hungarian National Museum in Budapest was used for our demonstration. The methodology and analysis procedures are described and the results obtained from the reconstruction of the 3D NRTI elemental image of the ancient object are compared with the results obtained from other neutron-based 3D imaging techniques.

Neutrons in the service of archaeological research

Abstract: Introduction Archaeology, as a discipline, is classified generally more to scholarly arts than science. Seemingly, it is very far from 'hard core' natural sciences. On a closer look, however, we find that it has many elements of natural sciences, in fact, modern archaeology cannot do without the effective help of scientific methods, physics included. At the primeval era of the discipline, archaeology relied most on visual observation and classification, much similar to 'style critics' approach of contemporary art historians. Prehistoric archaeology relied more on ethnographical observation, in a spirit of cultural anthropological research of our days. The necessity of setting up a reliable time scale, however, led to stratigraphical observations borrowed from earth sciences sneaking in the business. The break-through event in the relation of archaeology and natural sciences was obviously the invention and general spreading of radiometric dating methods, notably -C dating. This Nobleprize winning physical discovery has dramatically changed the paradigm of archaeology as a discipline and with the resulting change in thinking (i.e., archaeological argumentation can and should include natural sciences) gave rise to the revolutionary changes known as 'New Archaeology' (RENFREW-BAHN 1999).

Unwinding of a skyrmion lattice by magnetic monopoles.

Abstract: Skyrmion crystals are regular arrangements of magnetic whirls that exist in a wide range of chiral magnets. Because of their topology, they cannot be created or destroyed by smooth rearrangements of the direction of the local magnetization. Using magnetic force microscopy, we tracked the destruction of the skyrmion lattice on the surface of a bulk crystal of Fe(1-x)Co(x)Si (x = 0.5). Our study revealed that skyrmions vanish by a coalescence, forming elongated structures. Numerical simulations showed that changes of topology are controlled by singular magnetic point defects. They can be viewed as quantized magnetic monopoles and antimonopoles, which provide sources and sinks of one flux quantum of emergent magnetic flux, respectively.

Neutron resonance spectroscopy for the characterization of materials and objects

Abstract: The resonance structure in neutron induced reaction cross sections can be used to determine the elemental compositions of materials or objects. The occurrence of resonances is the basis of neutron resonance capture analysis (NRCA) and neutron resonance transmission analysis (NRTA). NRCA and NRTA are fully non-destructive methods to determine the bulk elemental composition without the need of any sample preparation and resulting in a negligible residual activity. They have been applied to determine the elemental composition of archaeological objects and to characterize reference materials used for cross section measurements. For imaging applications a position sensitive neutron detector has been developed within the ANCIENT CHARM project. The detector is based on a 10 × 10 array of 6Li-glass scintillators mounted on a pitch of 2.5 mm, resulting in a 25 × 25 mm2 active area. The detector has been tested at the time-of-flight facility GELINA and used at the ISIS spallation source to study cultural heritage objects.