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Nonerasing dose readout in lithium fluoride crystals by positron lifetime spectroscopy
A Somoza1, A Dupasquier, M A Chesta
1IFIMAT, Universidad Nacional del Centro de la Provincia de Buenos Aires, Tandil, Argentina.
Radiation Research
|March 13, 1998
Summary
Positron mean lifetime in lithium fluoride (LiF) chips correlates with gamma radiation dose. This suggests positron lifetime spectroscopy can read LiF dosimeters without erasing stored dose information.
Area of Science:
- Nuclear Physics
- Materials Science
- Radiation Dosimetry
Background:
- Lithium fluoride (LiF) is a widely used material for thermoluminescent dosimetry (TLD).
- Gamma irradiation of LiF crystals creates defects that store dose information.
- Current readout methods for LiF TLDs can sometimes alter the stored information.
Purpose of the Study:
- To investigate the relationship between positron mean lifetime and gamma radiation dose in LiF crystals.
- To explore the feasibility of using positron lifetime spectroscopy for reading LiF TLDs.
- To determine if this method can preserve the stored dose information.
Main Methods:
- Irradiating LiF chips with varying doses of 60Co gamma rays (up to 40 Gy).
- Measuring the positron mean lifetime (tau) in the irradiated LiF chips.
- Analyzing the correlation between measured positron mean lifetime and delivered radiation dose.
Main Results:
- A clear correlation was observed between the positron mean lifetime and the gamma radiation dose delivered to the LiF crystal.
- The positron mean lifetime changes measurably with increasing radiation dose.
- This correlation suggests a potential new readout mechanism.
Conclusions:
- Positron lifetime spectroscopy is a viable method for reading gamma-irradiated LiF thermoluminescent dosimeters.
- This technique offers a non-destructive readout, preserving the stored dose information.
- Further research can optimize this method for practical dosimeter applications.