Muography applied to archaeology: case study of a small size Macedonian Tumulus

Cultural Tourism in Greece at a Time of Economic Crisis

This special issue on the Management of Archaeological Sites in Greece discusses the context within which archaeological site management takes place in the country and aims to address the problems ...

Since February 2018, simultaneous observation of cosmic ray (CR) muon and neutron is continued. The operation is quite stable and its duty cycle is higher than 95%. These detectors are showing their usefulness by responding to, for example, a peculiar CME event in August 2018. There is another interesting event in September 2019. A Sudden Stratospheric Warming (SSW) was observed and muon counts responded to the SSW. This response is caused by that muon counts on the ground are affected by high altitude temperature. Temperature effect on CR muon now can be corrected with high altitude temperature data. There is, however, some matter of research about how the method works. This event seems to be valuable to improve correction method. We describe a character of muon and neutron data accumulated during the last three years and discuss potential use in studying atmospheric effect on CR muon and neutron count rates.

Spontaneous plants are an integral part of the archaeological landscape. The indigenous vegetation of the archaeological landscape can play a significant role in preserving the atmosphere of a place, as well as an additional element for education and recreation. Spontaneous vegetation was recorded in seven archaeological sites around Greece. Field surveys were conducted over two vegetative seasons, spanning spring and autumn, and data were gathered from both the surfaces of the monuments and the open field areas adjacent to these monuments. Therophytes were dominant on and around monuments across all sites throughout both the spring and autumn recording seasons. The three most abundant botanical families, in terms of species, found within the archaeological sites were Fabaceae, Poaceae, and Asteraceae. Based on the calculation of species diversity and evenness indices, it appeared that the sites exhibited high values during the spring period. The cluster and principal component analyses revealed that plant species tend to form clusters associated with the hosting archaeological sites, while the archaeological sites create variations that concern the species growing within them. The above is particularly significant as it implies that each archaeological site possesses a distinct and unique floristic identity, which can be utilized as an additional layer for education and enjoyment, enhancing the economic sustainability of these sites.

Weed species commonly colonize archaeological sites in the Mediterranean region, which poses many issues for the sites’ function and the state of preservation of the monuments. Soil solarization was investigated as an alternative environmentally friendly weed control strategy following legislative limits on the use of herbicides at archaeological sites in Greece. The aim of the study was to evaluate the effectiveness of solarization applied during: (a) summer (the hottest season, as applied in organic and integrated agriculture) and (b) autumn (a season of low tourist activity in archaeological sites), testing two types of plastic mulching: (a) clear and (b) opaque black, and two types of soil preparation: (a) with tillage (as in the agricultural practice of the method) and (b) without tillage. Visual evaluation of the weed control rate suggested that the application of soil solarization during summer resulted in excellent weed control, 100% the following October to December period and over 90% until February. The application of soil solarization during autumn also provided excellent weed control and treatments with clear plastic and tillage resulted in complete (100%) weed control from October to December, while the following month weed control was over 90%. In late March, dry weight of weed biomass was significantly affected by the solarization treatments and it was significantly reduced by treatments with clear plastic. Thus, soil solarization is a sustainable method that has the potential to be used effectively for weed management in archaeological sites of the Mediterranean region. Even treatments without tillage generated excellent weed control during the winter weed flush period and are recommended to protect unexcavated, fragile artifacts. Also, the results of autumn treatments encourage the application of the method during the season of low tourist activity at archaeological sites.

Observations made soon after recent major earthquakes in Algeria, California and Japan have shown that repeated motions on buried fault planes in seismically active areas cause incremental folding of the overlying rocks and sediments. The deformation causes characteristic changes to river profiles and is therefore a factor which must be considered when applying techniques of site catchment analysis in areas of tectonic uplift. Here we examine the relationship between tectonic uplift and the palaeoenvironments of palaeolithic sites in North-west Greece, which is one of the most seismically active areas of Europe. Uplift can substantially alter local topography and sediment distributions and therefore undermine the economic viability of human settlements. Paradoxically uplift can also create stable conditions highly favourable to long-term habitation in two ways: by maintaining well-watered sediment traps which provide a climatically insensitive environment; by accentuating enclosed topography, which facilitates the control of mobile prey species.

Rockfalls pose a significant risk to human activities and infrastructure. The assessment of rockfall risk is critical in deligneating zones of higher risk and mitigating effectively the potential impact from such events in inhabited areas. Risk assessment relies heavily on predicting accurately the trajectories of falling rocks, considering various factors such as the rock slope characteristics, the properties of the falliing rocks, the triggering mechanism and other. In the last two decades, risk assessment is performed more frequently using three dimensional rockfall analysis allowing for more robust asssement of risk. The paper presents an example of a 3D rockfall analysis, which assessed the risk from rockfalls at a cultural heritage site in Central Greece. The site is characterised by an Acropolis situated at the crest of a promontory, which is formed by steep limestone slopes. Following detailed UAV surveying of the study area, engineering geological mapping of rockfall prone areas, discontinuity mapping using different techniques and field measurements to identify the prevailing conditions on the slope, the analyses where performed using Rockyfor3D software in order to calculate the rockfall trajectories under different scenarios. The 3D analyses results were compared to 2D rockfall analyses, to evaluate the accuracy of the two approaches. It was concluded that the 2D analysis predicted well the rockfall trajectories, in relation to the 3D analyses, but the zoning of high risk zones was only possible when the 3D analyses where utilised. Different scenaria (i.e. earthquake triggered events) were assessed to determine the appropriate mitigation measures and zone areas where no further development should take place.

Production of X-rays by cosmic-ray muons in heavily shielded gamma-ray spectrometers

We demonstrate that high-Z material can be detected and located in three dimensions using radiographs formed by cosmic-ray muons. Detection of high-Z material hidden inside large volume of ordinary cargo is an important and timely task given the danger associated with illegal transport of uranium and heavier elements. Existing radiography techniques are inefficient for shielded material, often expensive and involve radiation hazards, real and perceived. We recently demonstrated that radiographs can be formed using cosmic-ray muons [K. N. Borozdin et al., Nature (London) 422, 277 (2003)]. Here, we show that compact, high-Z objects can be detected and located in three dimensions with muon radiography. The natural flux of cosmic-ray muons [P. K. F. Grieder, Cosmic Rays at Earth (Elsevier, New York, 2001)], approximately 10 000 m−2 min−1, can form useful images in ∼1 min, using large-area muon detectors like those used in high-energy physics.

Ground cosmic ray muon measurements have extensive applications in weather and climate change prediction and muon tomography. However, for comprehensive understanding of the relationship between cosmic ray muon and various weather phenomena, the cosmic ray muon flux needs to be determined accurately at various geographical locations. Toward this objective, this report presents an advanced readout electronics system with a multichannel application-specific integrated circuit (ASIC) chip for a portable cosmic ray muon detector. This ASIC chip consists of high-speed comparators and an excellent time-resolution digital circuit module. Furthermore, it can provide all-digital outputs associated with the flux and zenith angles of incident cosmic ray muons. A 32-channel prototype readout ASIC chip was designed and fabricated in a 180-nm mixed-signal CMOS process, and the chip size was 3.9 mm2. A double-layer plastic scintillator muon detector was used to test the performance of this chip. The time resolution of the chip was approximately 5 ns, and its power consumption was only 1.6 mW/channel. Compared with the existing muon readout electronics system, the proposed system has advantages such as low cost, low power, high reliability, small size, and lightweight and is highly suitable for portable real-time cosmic ray muon detection. The final version of this chip will be used to construct a ground cosmic ray muon measurement network for long-term monitoring of cosmic ray muon flux variations around the world.

The Western Greece is one of the most tectonically active regions in the Mediterranean Sea, due to the subduction of the African plate underneath the Eurasian plate. The past years, major earthquakes occurred in Western Greece, causing destructions and casualties. Ancient Olympia, located in the North West of the Peloponnese in Western Greece, combines a great cultural background with natural beauty and is also associated with the Olympic Games. It is among the most visited archaeological sites in Greece, as it combines cultural tourism, eco-tourism and sports tourism. However, the complex tectonic field of Western Greece, including the broader area around Ancient Olympia, raises awareness and dictates the adoption of preventive and recovery measures in case of an earthquake risk in Western Peloponnese. Therefore, we propose an emergency and recovery plan for an earthquake risk scenario, that will be implemented in the broader area around the archaeological site of Ancient Olympia. Satellite and geospatial data are processed to extract all necessary thematic information. Additionally, multi-temporal InSAR analysis of Sentinel-1 images, is performed to identify areas exposed to ground deformation phenomena, therefore vulnerable during an earthquake. Detailed thematic information layers, combined with the identification of ground instabilities in the wider area around Ancient Olympia, will contribute to an efficient evacuation and reconstruction plan. Since cultural heritage sites are often exposed to various hazards, including geohazards, preparedness, risk assessment and emergency management near cultural heritage sites, is of great importance for their protection and preservation.   Acknowledgements The research was funded by the Working Programme 2021 under the Caroline Herschel Framework Partnership Agreement on Copernicus User Uptake.

Dendroarchaeology in Greece – From humble beginnings to promising future

A recent example of successful technology transition from high energy physics to practical engineering applications is cosmic ray muon tomography. Cosmic ray muon tomography, is a promising non-destructive technique that has been recently utilized to monitor or image the contents of dense or well shielded objects, typically not feasible with conventional radiography techniques, e.g., x-ray or neutron. Cosmic ray muon tomography has been used with various levels of success in spent nuclear fuel monitoring, volcano imaging, and cargo container imaging. Further, knowledge of cosmic ray muon momentum spectrum has the potential to significantly improve and expand the use of a variety of recently developed muon-based radiographic techniques. However, existing muon tomography systems rely only on muon tracking and have no momentum measurement capabilities which reduces the image resolution and requires longer measurement times. A fieldable cosmic ray muon spectrometer with momentum measurement capabilities for use in muon tomography is currently missing. In this paper, we will discuss and explore recent advances in cosmic ray muon computed tomography and spectroscopy and their applications to engineering including a new concept for measuring muon momentum using multiple gaseous Cherenkov radiators. By varying the pressure of multiple gas Cherenkov radiators, a set of muon momentum threshold levels can be selected that are triggered only when the incoming muon momentum exceeds that level. As a result, depending on the incoming muon momentum, none to all Cherenkov radiators can be triggered. By analyzing the signals from each radiator, we can estimate the actual muon momentum.

O substrato de um mosaico de pavimento é composto por uma variedade de camadas preparatórias assentes sobre um terreno nivelado ou sobre um pavimento previamente existente. Os substratos de mosaicos podem diferir entre si em número, espessura e natureza das camadas de argamassa. Neste sentido, foi considerado relevante registar de que forma se relacionam estas diferenças com o período histórico, posição geográfica, função dos pavimentos no edifício, tecnologia dos substratos. Um grupo de substratos de mosaicos dos períodos Helenístico e Romano, provenientes de sítios arqueológicos localizados na Grécia e em Itália, estão correntemente em estudo. A estratigrafia dos substratos é registada in-situ, e são recolhidas amostras de cada camada de argamassa para análise em laboratório através de diferentes técnicas. Os resultados até agora obtidos indicam que as características das camadas de argamassa dos substratos romanos dependem claramente da sua posição na estratigrafia do substrato, enquanto que, no caso dos substratos helenísticos, as características das camadas de argamassa variam comparativamente menos com a posição estratigráfica. Os resultados mostram ainda que os substratos de mosaicos de pavimento diferem consoante a função deste último no edifício.

The article examines several cases of contested sites, situating the sometimes fraught relationship between proponents of religion and archaeology—with their competing claims to authority and ‘truth’—within the longstanding contest between Religion and Science. In particular the article addresses cases where sites in Greece (classical temples), Ireland (the Hill of Tara), Britain (Avebury, Stonehenge, the Rollright Stones) and Estonia have been contested by archaeologists and modern Pagans. Such contests begin with the ways in which places are named and discursively framed (‘holy’ or ‘sacred place’ versus ‘archaeological site’), which in turn have material consequences for what happens at sites: how they are presented, represented, preserved, experienced and made available for different kinds of use by different kinds of people. The paper shows that archaeologists and Pagans are not always on opposite sides. Given that the State frequently has the ultimate power to determine what happens at heritage sites, Pagans’ alignments or negotiations with State agendas in relation to sites can make a difference to their ability to contribute to sites’ meanings, management, protection and use.