Pieter Meyers

Neutron Activation Analysis of Limestone Objects: A Pilot Study

The elemental compositions of samples from limestone objects were determined by neutron activation analysis to investigate whether this technique can be used to distinguish between objects made of limestone from different sources. Samples weighing between 0 . 2 2 grams were obtained by drilling from a series of ancient Egyptian and medieval Spanish objects. Analysis was performed on aliquots varying in weight from 4 0 1 0 0 milligrams. The following elements were determined quantitatively: Na, K, Rb, Cs, Ba, Se, La, Ce, Sm, Eu, Hf, Th, Ta, Cr, Μη, Fe, Co and Zn. The data on Egyptian limestones indicate that, because of the inhomogeneous nature of the stone, 0 . 2 2 gram samples may not be representative of an entire object. Nevertheless, multivariate statistical methods produced a clear distinction between objects originating from the Luxor area (ancient Thebes) and objects found north of Luxor. The Spanish limestone studied appeared to be more homogeneous. Samples from stylistically related objects have similar elemental compositions while relative large differences were observed between objects having no relationship other than the common provenance of medieval Spain.

Determination of major components and trace elements in ancient silver by thermal neutron activation analysis

Thermal neutron activation of minute samples of ancient silver objects has provided useful information concerning their silver, copper and gold content. The results of such analysis of eighteen Sasanian silver objects are discussed together with consideration of the sampling problems involved. In order to extend these measurements to include other elements, an isotopic exchange system has been developed to separate other activities present in irradiated silver specimens quantitatively from the silver, copper and gold activities. Following exchange with cuprous and silver iodides it has been possible to count quantitatively the activity of fourteen additional elements: As, Br, Co, Cr, Fe, Hg, Ir, K, Mn, Na, Sb, Sc, Se and Zn.

AUTHENTICATION OF PAINTINGS BY RALPH A. BLAKELOCK THROUGH NEUTRON ACTIVATION AUTORADIOGRAPHY.

Following his mental collapse at the end of the nineteenth century the paintings of Ralph A. Blakelock suddenly began to bring exceptionally high prices. Not surprisingly, therefore, many forgeries attributed to him were produced in the early twentieth century. In fact, some experts consider him to have been the most widely forged American painter. At Brookhaven National Laboratory a group of paintings attributed to him have been studied by thermal neutron activation autoradiography combined with solid state high resolution gamma-ray spectroscopy. Most of the paintings studied were of unquestioned authenticity coming from the collection of the Metropolitan Museum of Art, the National Collection of Fine Art of the Smithsonian Institution, the Sheldon Memorial Art Gallery of the University of Nebraska, and two private collectors with well established histories of acquisition. These included paintings produced by Blakelock both before and after his breakdown. In general a number of characteristic consistencies in the types of pigments and media used and how they were employed in these paintings were revealed by the activation study. Of course, major differences exist between his early and later work. However, a lack of these characteristics and hidden overpainted details which are not revealed in conventional X-ray radiographs have provided evidence that two of the paintings attributed to Ralph Blakelock are the work of other artists.Some paintings of Blakelocks contemporaries George Inness and Albert Ryder have also been investigated.

Cross sections for the production of some millisecond isomers by 14 MeV Neutrons

Abstract Millisecond isomers were produced by irradiation of several nuclides with 14 MeV neutrons. Cross sections for reactions from targets of Mg, Al, As, Y, In, Pb and Bi are reported in table I.

TECHNICAL EXAMINATION OF THE CLASSICAL BRONZE HORSE FROM THE METROPOLITAN MUSEUM OF ART

AbstractA thorough technical examination of the Metropolitan Museum of Art Bronze Horse (Ace. No. 23.69) has revealed that the technical evidence used to condemn it does not hold up under critical evaluation. The composition of the metal and core, the nature of the corrosion and its method of manufacture are consistent with the object being of ancient origin. Thermoluminescence experiments performed on the ceramic core material of the horse have proved that the bronze horse was manufactured in antiquity.