Practical Application of an Algorithm to Identify Irregular Glow Curves in Personnel Thermoluminescent Dosimetry

  • Veronica Osorio Piniella (Autor)
  • Hannes Stadtmann (Autor)
  • Ernst Lankmayr (Autor)

Aktivität: Vortrag ohne Tagungsband / VorlesungPräsentation auf einer wissenschaftlichen Konferenz / Workshop

Beschreibung

In the last YISAC conference a new algorithm to identify irregular glow curves in thermoluminescent personnel dosimetry was presented. The Dosimetry Service Seibersdorf analyses monthly a large number of LiF (TLD 100, BICRON) dosemeters. In rare cases the luminescent glow curves of the routine analyse do not have the expected form due to external contamination, hardware problems, etc. Therefore an algorithm to identify such glow curves was developed. It is based on the fact that the form of an abnormal glow curves differs from the form of a typical normal one. All the curves are normalised with respect to the total area to avoid the influence of the dose and each curve is divided into four regions of interest (ROI). The relationships between the ROIs were analysed and few criteria combining all four ROIs which permit to identify irregular glow curves were found. The algorithm is applied to the routine glow curves in order to recognise the abnormal ones. It is also interesting to know the reason of the irregularity. For that different studies trying to reproduce the irregular glow curves were made. So dosemeters were treated in different ways (i.e. contaminated with substances like dust, hand creme, soap...or exposed to non-ionising radiation) and under different environmental conditions (high humidity, high temperature). Investigations concerning a special spurious problem are presented in this paper. An interesting type of irregular glow curves with very high signals (corresponding dose values and an untypical shape were found in the routine curves of a certain client, a steel industry. The dosemeters of that industry were intensively studied and a superficial chemical contamination were found. These contamination comes from a powder used in the continuous casting process for purify the steel product. The powder was analysed with ICP-AES after Multiwave dissolution. Many elements were found after the quantitative analysis. Elements like Aluminium, Barium, Calcium or Magnesium could produce thermoluminescent signals, such elements are used in different compounds as thermoluminescent materials (for example Al2O3, BaF2, BaSO4, CaF2, CaSO4, MgB4O7, MgO, Mg2SiO4, MgF2). The presence of those elements in the surface contaminant can produce new signals that interfere in the dosimetric signal of interest. These signals can be produced by means of excitation or process like photo-, tribo-, chemiluminescence, etc. Additionally investigations are being carried out at the moment in order to identify the chemical form of those elements in the powder and recognise the way in which the interference occurs. Furthermore special precautions to prevent dosemeter to be contaminated are being introduce in the routine service.
Zeitraum2 Juli 20015 Juli 2001
Ereignistitel8th Young Investigators' Seminar on Analytical Chemistry (YISAC'01)
VeranstaltungstypSonstiges
BekanntheitsgradInternational

Research Field

  • Biosensor Technologies

Schlagwörter

  • Seibersdorf
  • Thermoluminescent
  • YISAC
  • Dosimetry
  • Personendosimetrie
  • Personnel
  • Dosimetrie
  • Curves
  • Glühkurve
  • Glow