"TL-authentication"
TL-systems:
Littlemore - Tl 711
Littlemore-Elsec Tl-7188
Daybreak Tl 1150; Tl 1100; Daybreak OSL
Alpha - Counter Littlemore 7286
2 Alpha and Beta Multiple Sample Irradiater Littlemore and 2 Daybreak
Filter:
Corning 7-59 / 5-60; Schott BG-39
ß-Source:
Sr 90 40 mCi 101,623 cGy /min 01.01.2010
a-Source:
CM-244 Curium 0,5 mCi
Working method:
Fine grain sedimentation following treatment in diluted hydrochloric acid.
Grain size fraction following repeated sedimentation 20-50 micro m.
Measurements are carried out in an ultra- pure nitrogen atmosphere of
at least 4.6 N2 following a previous vacuum of 0,150 mbar.
Regeneration and addition method;
Result provides a statement on the last time of firing.
The age specification contained in the TL expertise refers to the so-called "firing age"
of the sample(s) (minerals), i.e. to the time at which they were last heated to a temperature
of over 500 degrees C and mentions the place on the object from which the sample (s)
was / were taken.
TL measurements to specify age can be falsified if objects have been subjected to high X and
Y radiation doses or neutron bombardment.
X - radiation, for example during the course of baggage controls, is no significance.
( Error factor under 0,1 % )
The TL-Report do not provide on the investigation of polymers (synthetic and natural resins)
of all kinds.If an object has been re-modelled, the date of the sample will the last firing and
not the date of re-modelling.
Sampling:
Samples are taken using a carbide drill (diameter 1,4 -2mm) at low speed following previous
removal of the surface.
Samples must be taken not under a strong incidence of light. As a rule, two samples are taken from each test
specimen, which are subjected to two seperate TL analyses , in each case specifying the drilling position.
The sample quantities are minimal (50-200 mg). If restoration work of the samples is discovered in one of the
objects to be tested, the TL expertise carries the appropriate reference.
Condition and restauration on the objects can be proofed by separate methods!!
Photos:
The laboratory requires two photos for the compilation of a Tl expertise.
The laboratory guarantees strict confidentiality in the processing of TL-analyses and the compilation of
TL expertises.
Expertises are printed out without specifying the name of the commissioning party.
