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Section 3. Archiving Thermoluminescence Data#

3.1 Deciding What to Archive#

The size of the acquired files containing TL-data can be very small (in most cases only few kilobytes) and thus, practically, there is not a dilemma about choosing the appropriate files to archive. In any case, the resulting TL-data file(s) should always be archived along with the file(s) which describe the detailed sequence of steps followed (i.e. complete experimental conditions and procedure) during the TL measurement of the various samples or sub-samples. This allows the prompt matching of results with the appropriate measurement and sample.

Furthermore, it is good practice to store and archive additional information describing the objects, such as photos, archaeological observations and information, and related research reports in order to enhance the usability of the TL data by other researchers or future studies.

3.2 Deciding How to Archive#

To the Authors' best knowledge there are not any established standards which would dictate the content and related fields that a database of TL data should be composed of. As a result, TL data are mainly stored in custom-made repositories of arbitrary structure. In any case such a database should always be structured on the premise that TL data should be publicly available and freely shared to other researchers in order to enhance archaeological research and contribute to cultural heritage management.

The minimum requirements regarding the structure of such a database should at least fulfil the need to allow future re-evaluation or verification of certain TL measurements. However, one should always have in mind that it is good practice to build such a generic repository covering a wide range of metadata, which would allow the comparison of results among different TL-data-producing instruments and their use in follow-up research.

3.3 File Types for Archiving#

As previously stated, the format of the TL data is native or proprietary. Consequently, besides their original format, raw data should also be converted and stored in ASCII format in order to enhance their readability by other researchers and in other studies. Furthermore, most metadata are descriptive in nature and thus should be stored preferably in accessible text format, while images/photographs of the objects should be stored in a commonly used image file format (jpg or tiff being the most appropriate).

3.4 Archiving TL-related Metadata#

Required metadata can be divided into three levels: Project level, Object level, and Measurement level, with each one providing different information. Project level metadata mainly refers to information related to the archaeological site at which the object(s) was found. Object level metadata provides information (mainly archaeological) and descriptions of every object to be measured. Finally, measurement level metadata relates to all available information about the experimental/measuring procedure including any post-measurement data treatment. Based on the above, a project may include multiple measurements of several objects found in the same excavation site.

Although the more metadata recorded the better, in most cases a certain minimum set of metadata is enough to establish their usability for future purposes. Table 1 presents all metadata that should be stored when archiving TL data.

Table 1: Metadata fields (M: Mandatory, D: Desirable, O: Optional) that should be filled when archiving TL data.

ElementDescriptionField Importance
Project level
Project nameName of the projectM
Project dateDate the project startedM
Name of stakeholderName of excavation, museum, collection, archaeological project, etc., where the objects come fromM
Object locationGeographical area, where the object(s) was found or stored or excavation site or name of MuseumM
Site geographical longitudeLongitude of the excavation siteD
Site geographical latitudeLatitude of the excavation siteD
Object level
Object ID codeThe ID of the object as registered in the excavation or museumM
Object lab IDThe ID of the object registered by the laboratory performing the measurementM
Object lab dateDate the object was delivered to the laboratoryM
Batch protocol numberThe protocol number of the batch in which the object belongsD
Group object IDThe ID of the group to which the object belongs (archaeological excavation)O
Excavation sectionThe section of the excavation site in which the object was foundO
Area descriptionDescription of the area where the object was found (e.g. in a kiln)M
Object depthThe depth from the surface where the object was foundM
Object typeThe type of object (e.g. soil, clay, sherd, brick, other)M
Object categoryThe category where the object belongs (mainly applicable for ceramics) according to the archaeological classificationO
Object dimensionsThe dimensions of the object in cm (length, width, height). Not applicable for powder objects (e.g. soil)O
Object descriptionFree text describing the object (colors, texture, etc)O
Object picturePicture or filename of the object in tiff or jpg formatD
Related documentsOther related documents (e.g. other object pictures, pictures from the area where the object was found, bibliography etc.)O
Measurement level
Sample preparationFree text describing the preparation/pretreatment of the sample (cleaning, sieving, etc.)M
Measuring techniqueTechnique used for the TL measurement (e.g. fine grain, coarse grain, etc.)M
Grain sizeSize of the grains used for measurementM
Number of aliquotsThe number of sub-samples used for measurement for statistical purposesM
Measurement protocolFile describing the steps and the operational conditions of the measurement protocolM
FiltersDetails of the optical filters used for TL measurementM
Instrument(s)Instrument(s) used for TL measurement (brand name, model and serial number)M
Instrument(s) detailsOther instrument details (especially those that are unique for the specific instrument (s) used)O
LaboratoryName of Laboratory performing the measurementM
Researcher(s)Name of the Researcher(s) who conducted the measurementsD
Start measurement dateThe date the measurement of the sample startedM
End measurement dateThe date the measurement of the sample endedM
Date of resultsThe date the results (age) were producedD
Technical Report fileTechnical report of the measurement (text file)M
Annual dose estimationMethods and/or assumptions used for the determination of the annual doseD
Method for potassium (if applicable)Method used for the determination of the sample's potassium (K) concentration (ICP, XRF etc)D
Method for uranium/thorium (if applicable)Method used for the determination of the sample's uranium (U) and thorium (Th) concentrationD

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