I have been wondering if the shape of the thermoluminescence glow curve of any mineral can change (even subtly) under varying β-particle energies. Put differently, if a mineral is irradiated by packages of progressively higher β-particle energies will the relative peak intensity of the TL signal change? Would such a change be observable?
The major difference in TL material with energy is the depth of activation, not the shape of the glow curve.
I wonder if you mean the change in the dose of the Beta radiation or the energy of the Beta particles. If the TL peak is not of first order, it is expected to shift to lower temperature with higher doses and the shape of the peak may somewhat change. If you are talking about changing the energy of the Beta particles, this effect is not expected. However, when you use a number of Beta sources and compare the shape of the TL peak, you have to make sure that the dose is kept the same.
Dear Constantin
As far as I remember for the case of quartz, the shape does not change. However, the TL sensitivity will possibly change.
Thank you Reuven. I mean keeping the dose constant while changing the energy of the beta particles. Joseph previously mentioned differences in the depth of activation. Does this imply that some changes may be expected in the high-temperature (e.g. > 400C) part of the signal?
Yes, there will be changes. In some TL materials, the efficiency for the excitation of different peaks is dependent on the ionization density (quantified by linear energy transfer, LET) of the radiation field and this determines the shape of the glow curve. This fact is used in space dosimetry to deduce the LET properties of cosmic rays and in medical appliactions to learn about the energy (or LET) evolution of proton beams used in radiotherapy. Of course, the magnitude of the change of the glow curve shape will depend on how large is the difference of ionization densities between radiation fields. The most used materials for this type of research have been TLD-100 and TLD-300. Do a search with keywords "LET dependence" "glow curve" "TL" and you will find plenty of fascinating results.
This sounds exciting. I will search for anything relevant on the web. Thank you!
Beta dosimetry is slightly tricky when it comes to TLDs. Ideally for thinnest possible TLDs, say micro layer, all beta sources will exhibit identical glow curves having nearly same peak Temp. However, LET dependent changes may occur that also for very low energy beta sources say 10 keV per micron (speculation)@Brandan)
For all beta sources say Pm-147, Kr-85, Tl204, Sr90/Y90, Natural uranium, Ru/Rh106, identical glow curves will result. However, TLDs are thick then shapes may be influenced to some extent due to other reasons and output counts will be source dependent due to energy dependence of response of tld to beta energies/sources which is due to thickness of TLD. Physics guides the beta response see -dE/dx from interaction of beta with materials Bethe Block formula for energy loss.
will the relative peak intensity of the TL signal change?
Yes, if the energy of the beta source is such that the corresponding range is less than the thickness of TLD.
For all energies having range much greater than thickness of TLD, equal counts or identical glow curves will result when equal doses rare delivered. Counts/mGy are independent of beta source once the TLD is too thin compared to the range of beta particles. So -dE/dx is independent of energy in that region.
- Badges
- Science topic
- Similar topics
- Econ
- Innovation Economics
- Innovation