TY - JOUR
T1 - Interpretation of single grain D-e distributions and calculation of D-e
AU - Jacobs, Z.
AU - Duller, G. A. T.
AU - Wintle, A. G.
N1 - Sponsorship: NERC EFCHED Grant
NER/T/S/2002/00677 (GATD)
PY - 2006/3
Y1 - 2006/3
N2 - Recent development of an instrument for measuring the optically stimulated luminescence signal from individual mineral
grains has made it practicable to measure the equivalent dose (De) from many hundreds or thousands of single mineral grains
from a sample. Such measurements can potentially be used to address issues such as sample integrity, and to make it possible
to obtain ages from samples that consist of mixtures of grains, enlarging the range of materials to which luminescence dating
can be applied. However, for reliable ages to be obtained, the characteristics of the equipment and the sample being analysed
need to be understood.
Using sensitised sedimentary quartz grains, the instrumental uncertainty in repeated optically stimulated luminescence
measurements made using a single grain laser luminescence unit attached to a conventional luminescence reader was evaluated;
a value of 1.2% was obtained. Grains from this sample were then used to investigate the uncertainty in a measured dose
distribution obtained using the single aliquot measurement protocol on each grain that had previously received a known
laboratory dose; after systematic rejection of grains that did not pass defined acceptance criteria, overdispersion of 7% was
found.
Additional spread in data was found when uniform aeolian sands were examined, resulting in overdispersion of ∼ 12%; this
was attributed to a combination of factors relating to differences in field and laboratory conditions. A similar value was found
for an archaeological horizon below this sand. For another sample from the same section, a significantly larger value was
found, ∼ 29%; on this basis the finite mixture model was applied to obtain the likely dose components. The paper demonstrates
the importance of correct assessment of error terms when analysing single grain De distributions and a number of rejection
criteria that are vital to avoid the inclusion of data that could lead to misinterpretation of the degree of scatter present.
AB - Recent development of an instrument for measuring the optically stimulated luminescence signal from individual mineral
grains has made it practicable to measure the equivalent dose (De) from many hundreds or thousands of single mineral grains
from a sample. Such measurements can potentially be used to address issues such as sample integrity, and to make it possible
to obtain ages from samples that consist of mixtures of grains, enlarging the range of materials to which luminescence dating
can be applied. However, for reliable ages to be obtained, the characteristics of the equipment and the sample being analysed
need to be understood.
Using sensitised sedimentary quartz grains, the instrumental uncertainty in repeated optically stimulated luminescence
measurements made using a single grain laser luminescence unit attached to a conventional luminescence reader was evaluated;
a value of 1.2% was obtained. Grains from this sample were then used to investigate the uncertainty in a measured dose
distribution obtained using the single aliquot measurement protocol on each grain that had previously received a known
laboratory dose; after systematic rejection of grains that did not pass defined acceptance criteria, overdispersion of 7% was
found.
Additional spread in data was found when uniform aeolian sands were examined, resulting in overdispersion of ∼ 12%; this
was attributed to a combination of factors relating to differences in field and laboratory conditions. A similar value was found
for an archaeological horizon below this sand. For another sample from the same section, a significantly larger value was
found, ∼ 29%; on this basis the finite mixture model was applied to obtain the likely dose components. The paper demonstrates
the importance of correct assessment of error terms when analysing single grain De distributions and a number of rejection
criteria that are vital to avoid the inclusion of data that could lead to misinterpretation of the degree of scatter present.
UR - http://www.scopus.com/inward/record.url?scp=27844432598&partnerID=8YFLogxK
U2 - 10.1016/j.radmeas.2005.07.027
DO - 10.1016/j.radmeas.2005.07.027
M3 - Article
SN - 1350-4487
VL - 41
SP - 264
EP - 277
JO - Radiation Measurements
JF - Radiation Measurements
IS - 3
ER -