Please note: This is version 1.2 of DRAC and is currently under development.

DRAC — User Guide

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DRAC has been designed to be straightforward to use and useful to the trapped charge dating community. Dose rate data is input into DRAC using a downloadable template and the output is generated in a .csv file, which can be downloaded and saved by the user. Details of the inputs required by DRAC and the outputs produced are given in the DRAC inputs and DRAC outputs tables below.

Details of the calculation process can be found in the accompanying journal article in Quaternary Geochronology. For those with access to this journal, it can be accessed at Durcan et al., 2015. Alternatively, a copy of the accepted author manuscript is available here.

In order to calculate a Ḋ using DRAC, simply:

1. Download the DRAC Input & Output template file and input your data and factor selections into the appropriate columns, taking care to use the correct units and referring to the inputs table below to ensure correct data input. Whilst not all data input fields are required for Ḋ calculation, each column should be populated including those not being used.
2. Copy and paste your data from the template directly into the data input box on the Calculator page. You can calculate Ḋ for up to 100 samples at a time. You should also provide a name for the suite of calculations.
3. Press calculate.
4. A DRACoutput.csv file will be produced (see example version, which can be downloaded). This file will contain all of the input data and table outputs listed below.

Please ensure you cite the use of DRAC in your work, published or otherwise. Please cite the website name and version (e.g. DRAC v1.2) and the accompanying journal article: Durcan, J.A., King, G.E., Duller, G.A.T., 2015. DRAC: Dose rate and age calculation for trapped charge dating. Quaternary Geochronology, submitted. [at present a download to the submitted document].

Downloads

• DRAC Input template
• DRAC Output template
• Supplementary Information
• Durcan et al., 2015

DRAC Inputs

Table Input	Name	Required	Description
TI:1	Project ID	Y	Inputs can be alphabetic, numeric or selected symbols (/ - () [] _). Spaces are not permitted.
TI:2	Sample ID	Y
TI:3	Mineral	Y	The mineral used for dating: quartz, feldspar or polymineral. Input must be “Q”, “F” or “PM”.
TI:4	Conversion factors	N	The conversion factors required to calculate dose rates from radionuclide concentrations. Users have the option of datasets from Adamiec and Aitken (1998), Guerin et al. (2011) or Liritzis et al. (2013). Input must be “AdamiecAitken1998”, “Guerinetal2011”, “Liritzisetal2013” or “X” if conversion factors are not required.
TI:5	External U (ppm)	N	Radionuclide concentrations in parts per million for Uranium, Thorium and Rubidium and % for Potassium. Inputs must be 0 or positive and should not be left blank.
TI:6	External δU (ppm)	N
TI:7	External Th (ppm)	N
TI:8	External δTh (ppm)	N
TI:9	External K (%)	N
TI:10	External δK (%)	N
TI:11	External Rb (ppm)	N
TI:12	External δRb (ppm)	N
TI:13	Calculate external Rb from K conc?	N	Option to calculate a Rubidium concentration from Potassium, using the 270:1 ratio suggested by Mejdahl (1987). Input should be yes “Y” or no “N”.
TI:14	Internal U (ppm)	N	Internal radionuclide concentrations in parts per million for Uranium, Thorium and Rubidium and % for Potassium. Inputs must be 0 or positive and should not be left blank.
TI:15	Internal δU (ppm)	N
TI:16	Internal Th (ppm)	N
TI:17	Internal δTh (ppm)	N
TI:18	Internal K (%)	N
TI:19	Internal δK (%)	N
TI:20	Internal Rb (ppm)	N
TI:21	Internal δRb (ppm)	N
TI:22	Calculate internal Rb from K conc?	N	Option to calculate an internal Rubidium concentration from Potassium, using the 270:1 ratio suggested by Mejdahl (1987). Input should be yes “Y” or no “N”.
TI:23	User external Ḋα (Gy.ka-1)	N	Users may input directly measured values for external alpha, beta and gamma dose rates (in Gy.ka-1). Any positive inputs in these fields will override dose rates calculated from radionuclide concentrations. Inputs should be 0 or positive and should not be left blank.
TI:24	User external δḊα (Gy.ka-1)	N
TI:25	User external Ḋβ (Gy.ka-1)	N
TI:26	User external δḊβ (Gy.ka-1)	N
TI:27	User external Ḋγ (Gy.ka-1)	N
TI:28	User external δḊγ (Gy.ka-1)	N
TI:29	User internal Ḋr (Gy.ka-1)	N	Users may input an internal dose rate (either alpha, beta or the sum of the two; in Gy.ka-1). DRAC will assume that this value has already been corrected for attenuation. Inputs in this field will override dose rates calculated from radionuclide concentrations. Inputs should be 0 or positive and not left blank.
TI:30	User internal δḊr (Gy.ka-1)	N
TI:31	Scale Ḋγ at shallow depths?	N	Users may choose to scale gamma dose rates for samples taken within 0.3 m of the ground surface. The scaling factors of Aitken (1985) are used. Input should be yes “Y” or no “N”.
TI:32	Grain size min (µm)	Y	The grain size range analysed. DRAC can be used for the grain size ranges between 1 and 1000 µm. Inputs should range between 1 and 1000 and not be left blank.
TI:33	Grain size max (µm)	Y
TI:34	α-Grain size attenuation factors	Y	The grain size attenuation factors for the alpha dose rate. Users have the option of datasets from Bell (1980) and Brennan et al. (1991). Input must be “Bell1980” or “Brennanetal1991”.
TI:35	β-Grain size attenuation factors	Y	The grain size attenuation factors for the beta dose rate. Users have the option of datasets from Mejdahl (1979), Brennan (2003) and Guerin et al. (2012) for quartz or feldspar. Input must be “Mejdahl1979”, “Brennan2003”, “Guerinetal2012-Q” or “Guerinetal2012-F” .
TI:36	Etch depth min (µm)	Y	The user defined etch depth range (µm). Inputs should range between 0 and 30 and not be left blank.
TI:37	Etch depth max (µm)	Y
TI:38	β-Etch attenuation factor	N	The etch depth attenuation factors for the beta dose rate. Users have the option of datasets from Bell (1979) and Brennan (2003). Input must be “Bell1979” or “Brennan2003”. Note: only the dataset of Bell (1980) is provided for attenuation of the alpha dose rate by etching.
TI:39	a-value	N	Alpha track efficiency value and uncertainty defined by the user. Inputs should be 0 or positive and not left blank.
TI:40	δa-value	N
TI:41	Water content (%)	Y	Sediment water content (%) over the burial period. Inputs should be 0 or positive and not be left blank.
TI:42	δWater content (%)	Y
TI:43	Depth (m)	N	Depth and uncertainty from which sample was extracted beneath the ground surface. Inputs should be 0 or positive and not left blank.
TI:44	δDepth (m)	N
TI:45	Overburden density (g.cm-3)	N	Density of the overlying sediment matrix from which the sample was taken. Inputs should be 0 or positive and not be left blank. The scaling calculation will use the overburden density and uncertainty provided.
TI:46	δOverburden density (g.cm-3)	N
TI:47	Latitude (decimal degrees)	N	Latitude and longitude of sample location (in degree decimals). Positive values should be used for northern latitudes and eastern longitudes and negative values for southern latitudes and western longitudes. Inputs should range from – 90 to 90° for latitudes and -180 to 180° for longitude.
TI:48	Longitude (decimal degrees)	N
TI:49	Altitude (m asl)	N	Altitude of sample location in metres above sea level. Input should be less than 5000 and not left blank.
TI:50	User defined Ḋc (Gy.ka-1)	N	Users may input a cosmic dose rate (in Gy.ka-1). Inputs in these fields will override the DRAC calculated cosmic dose rate. Inputs should be positive or “X” if not required, and not left blank.
TI:51	User defined δḊc (Gy.ka-1)	N
TI:52	De (Gy)	N	Sample De and uncertainty (in Gy). Inputs should be positive or “X” if not required, and not left blank.
TI:53	δDe (Gy)	N

DRAC Outputs

Table Output	Name	Description
TO:A	External U Ḋα (Gy.ka-1)	The calculated external dose rates from the provided radionuclide concentrations and selected conversion factors.
TO:B	External δU Ḋα (Gy.ka-1)
TO:C	External U Ḋβ (Gy.ka-1)
TO:D	External δU Ḋβ (Gy.ka-1)
TO:E	External U Ḋγ (Gy.ka-1)
TO:F	External δU Ḋγ (Gy.ka-1)
TO:G	External Th Ḋα (Gy.ka-1)
TO:H	External δTh Ḋα (Gy.ka-1)
TO:I	External Th Ḋβ (Gy.ka-1)
TO:J	External δTh Ḋβ (Gy.ka-1)
TO:K	External Th Ḋγ (Gy.ka-1)
TO:L	External δTh Ḋγ (Gy.ka-1)
TO:M	External K Ḋβ (Gy.ka-1)
TO:N	External δK Ḋβ (Gy.ka-1)
TO:O	External K Ḋγ (Gy.ka-1)
TO:P	External δK Ḋγ (Gy.ka-1)
TO:Q	External Rb Ḋβ (Gy.ka-1)
TO:R	External δRb Ḋβ (Gy.ka-1)
TO:S	Internal U Ḋα (Gy.ka-1)	The calculated internal dose rates from the provided radionuclide concentrations and selected conversion factors.
TO:T	Internal δU Ḋα (Gy.ka-1)
TO:U	Internal U Ḋβ (Gy.ka-1)
TO:V	Internal δU Ḋβ (Gy.ka-1)
TO:W	Internal Th Ḋα (Gy.ka-1)
TO:X	Internal δTh Ḋα (Gy.ka-1)
TO:Y	Internal Th Ḋβ (Gy.ka-1)
TO:Z	Internal δTh Ḋβ (Gy.ka-1)
TO:AA	Internal K Ḋβ (Gy.ka-1)
TO:AB	Internal δK Ḋβ (Gy.ka-1)
TO:AC	Internal Rb Ḋβ (Gy.ka-1)
TO:AD	Internal δRb Ḋβ (Gy.ka-1)
TO:AE	U Ḋγ scaling factor	The scaling factors of Aitken (1985) used to correct gamma dose rates of samples taken from within 0.3 m of the ground surface.
TO:AF	Th Ḋγ scaling factor
TO:AG	K Ḋγ scaling factor
TO:AH	Average Ḋγ scaling factor
TO:AI	Depth scaled U Ḋγ (Gy.ka-1)	The gamma dose rates and uncertainties corrected for shallow depth (<0.3 m).
TO:AJ	Depth scaled δU Ḋγ (Gy.ka-1)
TO:AK	Depth scaled Th Ḋγ (Gy.ka-1)
TO:AL	Depth scaled δTh Ḋγ (Gy.ka-1)
TO:AM	Depth scaled K Ḋγ (Gy.ka-1)
TO:AN	Depth scaled δK Ḋγ (Gy.ka-1)
TO:AO	Depth scaled user external Ḋγ (Gy.ka-1)
TO:AP	Depth scaled δuser external Ḋγ (Gy.ka-1)
TO:AQ	External infinite matrix Ḋα (Gy.ka-1)	The infinite matrix external and internal dose rates. Calculated either from the radionuclide concentrations and conversion factors or the user defined dose rates. These values are used as the basis for all subsequent calculations.
TO:AR	External infinite matrix δḊα (Gy.ka-1)
TO:AS	External infinite matrix Ḋβ (Gy.ka-1)
TO:AT	External infinite matrix δḊβ (Gy.ka-1)
TO:AU	External infinite matrix Ḋγ (Gy.ka-1)
TO:AV	External infinite matrix δḊγ (Gy.ka-1)
TO:AW	Internal infinite matrix Ḋα (Gy.ka-1)
TO:AX	Internal infinite matrix δḊα (Gy.ka-1)
TO:AY	Internal infinite matrix Ḋβ (Gy.ka-1)
TO:AZ	Internal infinite matrix δḊβ (Gy.ka-1)
TO:BA	U Alpha grain size attenuation factor	The alpha grain size attenuation factors and uncertainties calculated from the selected dataset and for the specified grain size range. The value is calculated as the average of the attenuation factors for the two grain size extremes and the uncertainty is 50% of the range. If dose rates are calculated using radionuclide concentrations, they are attenuated individually. If a dose rate is provided by the user, it is attenuated using the combined attenuation factor.
TO:BB	δU Alpha grain size attenuation factor
TO:BC	Th Alpha grain size attenuation factor
TO:BD	δTh Alpha grain size attenuation factor
TO:BE	Combined alpha grain size attenuation factor
TO:BF	δCombined alpha grain size attenuation factor
TO:BG	U Alpha grain size absorption factor	The alpha grain size absorption factors and uncertainties calculated from the selected dataset and for the specified grain size range. The value is calculated as the average of the attenuation factors for the two grain size extremes and the uncertainty is 50% of the range.
TO:BH	δU Alpha grain size absorption factor
TO:BI	Th Alpha grain size absorption factor
TO:BJ	δTh Alpha grain size absorption factor
TO:BK	Grain size corrected external U Ḋα (Gy.ka-1)	The external and internal alpha dose rates corrected for grain size attenuation and absorption.
TO:BL	Grain size corrected external δU Ḋα (Gy.ka-1)
TO:BM	Grain size corrected external Th Ḋα (Gy.ka-1)
TO:BN	Grain size corrected external δTh Ḋα (Gy.ka-1)
TO:BO	Grain size corrected user external Ḋα (Gy.ka-1)
TO:BP	Grain size corrected user external δḊα (Gy.ka-1)
TO:BQ	Grain size corrected internal U Ḋα (Gy.ka-1)
TO:BR	Grain size corrected internal δU Ḋα (Gy.ka-1)
TO:BS	Grain size corrected internal Th Ḋα (Gy.ka-1)
TO:BT	Grain size corrected internal δTh Ḋα (Gy.ka-1)
TO:BU	U-Beta grain size attenuation factor	The beta grain size attenuation factors and uncertainties calculated from the selected dataset and for the specified grain size range. The value is calculated as the average of the attenuation factors for the two grain size extremes and the uncertainty is 50% of the range. If dose rates are calculated using radionuclide concentrations, they are attenuated individually. If a dose rate is provided by the user, it is attenuated using the combined attenuation factor based on the ratio of Mejdahl (1979).
TO:BV	U-δBeta grain size attenuation factor
TO:BW	Th-Beta grain size attenuation factor
TO:BX	Th-δBeta grain size attenuation factor
TO:BY	K-Beta grain size attenuation factor
TO:BZ	K-δBeta grain size attenuation factor
TO:CA	Rb-Beta grain size attenuation factor
TO:CB	Rb-δBeta grain size attenuation factor
TO:CC	Compiled beta grain size attenuation factor
TO:CD	δCompiled beta grain size attenuation factor
TO:CE	U-Beta grain size absorption factor	The beta grain size absorption factors and uncertainties calculated from the selected dataset and for the specified grain size range. The value is calculated as the average of the attenuation factors for the two grain size extremes and the uncertainty is 50% of the range.
TO:CF	U-δBeta grain size absorption factor
TO:CG	Th-Beta grain size absorption factor
TO:CH	Th-δBeta grain size absorption factor
TO:CI	K-Beta grain size absorption factor
TO:CJ	K-δBeta grain size absorption factor
TO:CK	Rb-Beta grain size absorption factor
TO:CL	Rb-δBeta grain size absorption factor
TO:CM	Grain size corrected external U Ḋβ (Gy.ka-1)	The external and internal beta dose rates corrected for grain size attenuation and absorption.
TO:CN	Grain size corrected external δU Ḋβ (Gy.ka-1)
TO:CO	Grain size corrected external Th Ḋβ (Gy.ka-1)
TO:CP	Grain size corrected external δTh Ḋβ (Gy.ka-1)
TO:CQ	Grain size corrected external K Ḋβ (Gy.ka-1)
TO:CR	Grain size corrected external δK Ḋβ (Gy.ka-1)
TO:CS	Grain size corrected external Rb Ḋβ (Gy.ka-1)
TO:CT	Grain size corrected external δRb Ḋβ (Gy.ka-1)
TO:CU	Grain size corrected user external Ḋβ (Gy.ka-1)
TO:CV	Grain size corrected user external δḊβ (Gy.ka-1)
TO:CW	Grain size corrected internal U Ḋβ (Gy.ka-1)
TO:CX	Grain size corrected internal δU Ḋβ (Gy.ka-1)
TO:CY	Grain size corrected internal Th Ḋβ (Gy.ka-1)
TO:CZ	Grain size corrected internal δTh Ḋβ (Gy.ka-1)
TO:DA	Grain size corrected internal K Ḋβ (Gy.ka-1)
TO:DB	Grain size corrected internal δK Ḋβ (Gy.ka-1)
TO:DC	Grain size corrected internal Rb Ḋβ (Gy.ka-1)
TO:DD	Grain size corrected internal δRb Ḋβ (Gy.ka-1)
TO:DE	U-Alpha etch attenuation factor	The alpha etch depth attenuation factors calculated from the Bell (1980) dataset for the specified etch depth. The value is calculated as the average of the attenuation factors for the etch depth extremes and the uncertainty is 50% of the range. If dose rates are calculated using radionuclide concentrations, they are attenuated individually. If a dose rate is provided by the user, it is attenuated using the combined attenuation factor.
TO:DF	U-δAlpha Etch attenuation factor
TO:DG	Th-Alpha etch attenuation factor
TO:DH	Th-δAlpha etch attenuation factor
TO:DI	Compiled alpha etch attenuation factor
TO:DJ	δCompiled alpha etch attenuation factor
TO:DK	U-Alpha etch absorption factor	Alpha etch depth absorption factors calculated from the Bell (1980) dataset for the specified etch depth. The value is calculated as the average of the attenuation factors for the etch depth extremes and the uncertainty is 50% of the range.
TO:DL	U-δAlpha Etch absorption factor
TO:DM	Th-Alpha etch absorption factor
TO:DN	Th-δAlpha etch absorption factor
TO:DO	Etch corrected external U Ḋα (Gy.ka-1)	The external and internal alpha dose rates corrected for etch depth attenuation and absorption.
TO:DP	Etch corrected external δU Ḋα (Gy.ka-1)
TO:DQ	Etch corrected external Th Ḋα (Gy.ka-1)
TO:DR	Etch corrected external δTh Ḋα (Gy.ka-1)
TO:DS	Etch corrected user external Ḋα (Gy.ka-1)
TO:DT	Etch corrected user external δḊα (Gy.ka-1)
TO:DU	Etch corrected internal U Ḋα (Gy.ka-1)
TO:DV	Etch corrected internal δU Ḋα (Gy.ka-1)
TO:DW	Etch corrected internal Th Ḋα (Gy.ka-1)
TO:DX	Etch corrected internal δTh Ḋα (Gy.ka-1)
TO:DY	U-Beta etch attenuation factor	The beta etch depth attenuation factors calculated from the selected dataset. The value is calculated as the average of the attenuation factors for the etch depth extremes and the uncertainty is 50% of the range. The uncertainty is ±2%. If dose rates are calculated using radionuclide concentrations, they are attenuated individually. If a dose rate is provided by the user, it is attenuated using the combined attenuation factor.
TO:DZ	U-δBeta etch attenuation factor
TO:EA	Th-Beta etch attenuation factor
TO:EB	Th-δBeta etch attenuation factor
TO:EC	K-Beta etch attenuation factor
TO:ED	K-δBeta etch attenuation factor
TO:EE	Compiled beta etch attenuation factor
TO:EF	δCompiled beta etch attenuation factor
TO:EG	U-Beta etch absorption factor	The beta etch depth absorption factors calculated from the selected dataset. The value is calculated as the average of the attenuation factors for the etch depth extremes and the uncertainty is 50% of the range.
TO:EH	U-δBeta etch absorption factor
TO:EI	Th-Beta etch absorption factor
TO:EJ	Th-δBeta etch absorption factor
TO:EK	K-Beta etch absorption factor
TO:EL	K-δBeta etch absorption factor
TO:EM	Etch corrected external U Ḋβ (Gy.ka-1)	The external and internal beta dose rates corrected for etch depth attenuation and absorption.
TO:EN	Etch corrected external δU Ḋβ (Gy.ka-1)
TO:EO	Etch corrected external Th Ḋβ (Gy.ka-1)
TO:EP	Etch corrected external δTh Ḋβ (Gy.ka-1)
TO:EQ	Etch corrected external K Ḋβ (Gy.ka-1)
TO:ER	Etch corrected external δK Ḋβ (Gy.ka-1)
TO:ES	Etch corrected user external Ḋβ (Gy.ka-1)
TO:ET	Etch corrected user external δḊβ (Gy.ka-1)
TO:EU	Etch corrected internal U Ḋβ (Gy.ka-1)
TO:EV	Etch corrected internal δU Ḋβ (Gy.ka-1)
TO:EW	Etch corrected internal Th Ḋβ (Gy.ka-1)
TO:EX	Etch corrected internal δTh Ḋβ (Gy.ka-1)
TO:EY	Etch corrected internal K Ḋβ (Gy.ka-1)
TO:EZ	Etch corrected internal δK Ḋβ (Gy.ka-1)
TO:FA	a-value corrected external U Ḋα (Gy.ka-1)	The external and internal alpha dose rates corrected for alpha track efficiency using the provided a-value.
TO:FB	a-value corrected external δU Ḋα (Gy.ka-1)
TO:FC	a-value corrected external Th Ḋα (Gy.ka-1)
TO:FD	a-value corrected external δTh Ḋα (Gy.ka-1)
TO:FE	a-value corrected user external Ḋα (Gy.ka-1)
TO:FF	a-value corrected user external δḊα (Gy.ka-1)
TO:FG	a-value corrected internal U Ḋα (Gy.ka-1)
TO:FH	a-value corrected internal δU Ḋα (Gy.ka-1)
TO:FI	a-value corrected internal Th Ḋα (Gy.ka-1)
TO:FJ	a-value corrected internal δTh Ḋα (Gy.ka-1)
TO:FK	External Dry Ḋα (Gy.ka-1)	The external dose rates corrected for grain size and etch depth attenuation.
TO:FL	External Dry δḊα (Gy.ka-1)
TO:FM	External Dry Ḋβ (Gy.ka-1)
TO:FN	External Dry δḊβ (Gy.ka-1)
TO:FO	External Dry Ḋγ (Gy.ka-1)
TO:FP	External Dry δḊγ (Gy.ka-1)
TO:FQ	Water corrected Ḋα	The water attenuated external alpha, beta and gamma dose rates.
TO:FR	Water corrected δḊα
TO:FS	Water corrected Ḋβ
TO:FT	Water corrected δḊβ
TO:FU	Water corrected Ḋγ (Gy.ka-1)
TO:FV	Water corrected δḊγ (Gy.ka-1)
TO:FW	Internal Dry Ḋα (Gy.ka-1)	The attenuated internal alpha and beta dose rates.
TO:FX	Internal Dry δḊα (Gy.ka-1)
TO:FY	Internal Dry Ḋβ (Gy.ka-1)
TO:FZ	Internal Dry δḊβ (Gy.ka-1)
TO:GA	Ḋ0 (Gy.ka-1)	The cosmic dose rate calculated at the sample depth, 55°N and sea level.
TO:GB	δḊ0 (Gy.ka-1)
TO:GC	Geomagnetic latitude	The geomagnetic latitude calculated from the sample latitude and longitude and sampling depth.
TO:GD	F	The factors required to correct the cosmic dose rate for altitude and geomagnetic latitude (after Prescott and Stefan, 1982).
TO:GE	H
TO:GF	J
TO:GG	Ḋc (Gy.ka-1)	The calculated or user defined cosmic dose rate used in final environmental dose rate calculation.
TO:GH	δḊc (Gy.ka-1)
TO:GI	External Ḋr (Gy.ka-1)	DRAC calculated external and internal dose rates.
TO:GJ	External δḊr (Gy.ka-1)
TO:GK	Internal Ḋr (Gy.ka-1)
TO:GL	Internal δḊr (Gy.ka-1)
TO:GM	Environmental Dose Rate (Gy.ka-1)	DRAC calculated environmental dose rate.
TO:GN	δEnvironmental Dose Rate (Gy.ka-1)
TO:GO	Age (ka)	Age, if De is provided, calculated using the DRAC determined dose rate.
TO:GP	δAge (ka)