Guides to Good Practice
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 fulfill 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.
| Element | Description | Field Importance |
|---|---|---|
| Project level | ||
| Project name | Name of the project | M |
| Project date | Date the project started | M |
| Name of stakeholder | Name of excavation, museum, collection, archaeological project etc, where the objects are coming from | M |
| Object location | Geographical area, where the object(s) was found or stored or excavation site or name of Museum | M |
| Site geographical longitude | Longitude of the excavation site | D |
| Site geographical latitude | Latitude of the excavation site | D |
| Object level | ||
| Object ID code | The ID of the object as registered in the excavation or museum | M |
| Object lab ID | The ID of the object registered by the laboratory performing the measurement | M |
| Object lab date | Date the object was delivered to the laboratory | M |
| Batch protocol number | The protocol number of the batch in which the object belongs | D |
| Group object ID | The ID of the group to which the object belongs (archaeological excavation) | O |
| Excavation section | The section of the excavation site in which the object was found | O |
| Area description | Description of the area where the object was found (e.g. in a kiln) | M |
| Object depth | The depth from the surface where the object was found | M |
| Object type | The type of object (e.g. soil, clay, sherd, brick, other) | M |
| Object category | The category where the object belongs (mainly applicable for ceramics) according to the archaeological classification | O |
| Object dimensions | The dimensions of the object in cm (length, width, height). Not applicable for powder objects (e.g. soil) | O |
| Object description | Free text describing the object (colors, texture, etc) | O |
| Object picture | Picture or filename of the object in tiff or jpg format | D |
| Related documents | Other related documents (e.g. other object pictures, pictures from the area where the object was found, bibliography etc.) | O |
| Measurement level | ||
| Sample preparation | Free text describing the preparation/pretreatment of the sample (cleaning, sieving, etc.) | M |
| Measuring technique | Technique used for the TL measurement (e.g. fine grain, coarse grain, etc.) | M |
| Grain size | Size of the grains used for measurement | M |
| Number of aliquots | The number of sub-samples used for measurement for statistical purposes | M |
| Measurement protocol | File describing the steps and the operational conditions of the measurement protocol | M |
| Filters | Details of the optical filters used for TL measurement | M |
| Instrument(s) | Instrument(s) used for TL measurement (brand name, model and serial number) | M |
| Instrument(s) details | Other instrument details (especially those that are unique for the specific instrument (s) used) | O |
| Laboratory | Name of Laboratory performing the measurement | M |
| Researcher(s) | Name of the Researcher(s) who conducted the measurements | D |
| Start measurement date | The date the measurement of the sample started | M |
| End measurement date | The date the measurement of the sample ended | M |
| Date of results | The date the results (age) were produced | D |
| Technical Report file | Technical report of the measurement (text file) | M |
| Annual dose estimation | Methods and/or assumptions used for the determination of the annual dose | D |
| 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) concentration | D |