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The SYNTH Windows software synthesizes results of gamma-ray spectroscopy experiments. It allows users to specify physical characteristics of a gamma-ray source, quantity of nuclides producing the radiation, the source-to-detector distance, type and thickness of the absorbers, size and composition of the detector (Ge, NaI or CdZnTe), and electronic set-up for data collection. SYNTH uses these specifications to generate a spectrum that includes photopeak transmission as a function of energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides.
Users can then compare the results to acquired spectrum in the field or laboratory. To generate the source term, SYNTH includes 3 gamma-ray libraries (TORI, PC-Nudat, and Erdtmann Soyka) that have over 3,400 nuclides, and over 90,000 gamma rays, alpha and beta particles. Overall, SYNTH enables gamma-ray spectroscopists to design experiments and quickly process the acquired data.
There are many applications of the SYNTH software. It's been used to provide timely and valuable support for spectroscopists in the form of simple “reality checks.” It could support development of detector systems for border patrol or customs to detect and identify radioactive material at ports of entry. The types of SYNTH applications are listed below. See illustrated chart.
| SYNTH Applications |
 Radiation Detector Test, Calibration and Configuration Design - Ge, NaI & CdZnTe |
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Nuclear Inspections |
Nuclear Safeguards |
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Neutron Detector Design |
Neutron
Activation |
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Front-End for Monte-Carlo Codes |
Military Research |
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Activation Spectra Analysis |
Activation Monitoring |
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Dosimetry Benchmarking |
Mixed-Field Neutron/Gamma Dosimetry |
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Pressure Vessel Decommissioning |
LWR Surveillance Dosimetry |
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Radiation Monitoring of Irradiation Experiments |
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Source Terms for Decommissioning of Reactor Components | |
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Reactor Surveillance Dosimetry and Plant Life Management |
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Dosimetry for Irradiation Facilities at Test & Research Reactors |
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Thermal and Low-Energy Neutron Dosimetry |
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Funded by the U.S. Department of Energy and developed by PNNL, SYNTH has many users around the globe. Users include: IAEA, U.S. DOE, CEA, other Government agencies and labs, nuclear reactor utilities, instrument engineering firms, military research centers, universities and other organizations involved in radiation research, protection, monitoring, design, benchmarking, and training. SYNTH is used in the United States, Europe, Canada and the Middle East.
To better understand how SYNTH operates, see the detailed example for Plutonium Oxide; it includes screen shots with
in-depth explanations. Some technical highlights of SYNTH are also presented below.
To order the SYNTH software or request more information, please go to the contact page.
SYNTH Screens Diagram
Absorber Selection
Example of Main Screen
for Defining Absorbers
The absorber selection menu initially
offers eight specific compounds and elements. Though these materials span
the range of electron densities, initial feedback from users indicated
that a more robust absorber model was desirable. The current version of
SYNTH retains all the original selections and allows up to nine additional
"User Defined" regions in which any element may be specified
as an absorber. Each element selected is initially offered at a default
density, but the density may be adjusted to any desired value. This capability
allows almost any absorber material to be simulated.
A graph of the composite transmission
function as a function of energy is displayed during the absorber selection
process, and is quite useful in itself. The display has an extra feature
that allows the user to interrogate the graph with the mouse to extract
numerical values, if needed.
Detector Specification
Example of Screen Used
to Define Detector
The detector specification
portion of the code uses a combination of hard-coded efficiency curves, and general algorithms such as those for germanium diodes. Regarding this example, SYNTH supports planar germanium and a wide range of coaxial germanium
detector sizes. The Ge intrinsic detector efficiency is computed from fundamental
detector parameters such as diameter, length and relative efficiency. An absolute efficiency is obtained by applying geometry factors to the computed intrinsic efficiency. Other relevant detector parameters
can also be entered and used to correct the detector efficiency. As shown, the detector dead-layer thickness for germanium detectors can be specified, which allows the user to evaluate the difference between an N-type (no external dead layer) and a P-type (0.5 to 1.0 mm external dead layer) detector. The effect of the end-cap material is also included. Stainless steel, aluminum, and beryllium end caps can be selected.
Panning and Zooming
Example of Pan / Zoom
Screen
An example showing the region around 1332 keV. The upper data is experimental
and the lower is predicted data with noise added to make it more
realistic. A spectrum is generated by first adding the full-energy peaks
specified in the "Source Term" module to the spectrum. The form
of an individual peak is a gaussian with a single-exponential tailing function.
The area of the peak is computed from the intensity of specified source
term (corrected for gamma-ray branching ratios), "counting" time, geometry factor, self attenuation in the source, transmission
through any absorbers, and intrinsic detector efficiency.
Next, the Compton continuum is added
to the spectrum by taking the theoretical shape of a Compton spectrum,
and normalizing it with a Peak-to-Compton ratio appropriate for the volume
of the detector. The impact on the spectrum due to other physical effects
is included, such as multiple Compton scattering (the region between
the full-energy peak and Compton edge), single and double escape peaks
(from pair production), the difference in peak shape of gamma and x-rays
(gaussian vs. lorentzian), the variation of resolution as a function of
energy, and others.
Because its computational models
are based on hard-coded algorithms (instead of Monte Carlo), SYNTH can generate a complex gamma-ray spectrum with hundreds of peaks in a few minutes. The result is a spectrum with accurate full energy peaks, Compton edges, single and double escape peaks, statistical fluctuations, and appropriate Peak-to-Compton ratios.
Options exist to include statistical
fluctuations, add (and normalize) a previously stored spectrum (real or
synthetic), and save the generated spectrum to disk. A group of display
options also allows detailed examination of the output spectrum and comparison
with a reference spectrum.
In the process of specifying the
parameters needed to synthesize a spectrum, several interesting intermediate
results are produced, including photopeak transmission as a function of
energy, a detector efficiency curve, and a weighted list of gamma and X-rays produced from a set of nuclides. All of these intermediate results
are available for graphical inspection and for printing.
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