This dataset includes ascii data for measured and calculated absorption
 coefficients for the paper described as: Design and Development of a Semtex
 Simulant Suitable for Measurements at THz Frequencies Using a Genetic
 Algorithm. This data was either collected using the system described or
 modelled using the method prescribed within the paper. The development and 
use of terahertz-frequency (THz) spectroscopy systems for security 
screening has shown an increased growth over the past 15 years. In order to
 test these systems in real world situations, safe simulants of illicit 
materials are required, particularly of explosives. Ideally simulants
 should mimic key features of the material of interest, such that it at
 least resembles or even appears indistinguishable from the material of
 interest to the interrogating technique(s), whilst not having hazardous or
 illicit properties. Ideally, simulants should: have similar physical
 properties such as malleability, density, surface energy, volatility etc; 
be non-toxic; be easy to clean and decontaminate from surfaces; be 
recyclable or disposable; and, be useable in a public environment. A THz 
explosive simulant would require spectral features at similar frequencies
 to those in a common explosive, in this instance Semtex-H, but would be 
safe to handle and be non-explosive. Here, we present a method for
developing such a simulant based on a database of THz spectra of common 
organic molecules, and the use of a genetic algorithm to select a mixture
 of compounds automatically to form such a simulant. We propose four
 mixtures that could then be used to test the response of any instrument, 
working at terahertz frequencies, without the need for an explosive 
substance.

########################################################################


File Format - Unless otherwise specified, all data is in column tabulated ascii
 format. At the top of the file meta information is included such as units 
used for data set and column titles.


######


comp_spectra.txt - raw library component (unnormalised) spectra. Contains - Frequency (THz) and Absorption coefficient (cm^-1) for
 components.
	note - number in column name refers to concentration of sample,
	unless otherwise stated, matrix material used was PTFE. F refers to
 Frequency, and is consistent between all data. Related figures - 1,2.


predicted_sim_spectra.txt - predicted mixture (unnormalised) spectra
. Contains - Frequency (THz) and Absorption coefficient (cm^-1) for
	simulant mixtures.
 note - sim X refers to mixture X in the paper. F refers to
 Frequency, and is consistent between all data.
 Related Figures - 4


measured_sim_powders.txt - measured powdered mixture spectra

. Contains - Frequency (THz) and Absorption coefficient (m^-1) for
 measured simulant mixtures.
 note - all simulant mixtures were diluted to 25%, with a PTFE
 matrix. Sim X refers to mixture X in the paper. F refers to
 Frequency, and is consistent between all data.

 Related Figures - 4,5


measured_sim1_plastic.txt - measured plastic form of simulant 1

. Contains - Frequency (THz) and Absorption coefficient (M^-1) for a measured simulant mixture.
	note - Sim 1 refers to mixture 1 in the paper. F refers to
 Frequency, and is consistent between all data.
 Related Figures - 5.