Calculations

What is the meaning of the “calculation precision” number I have to choose?

Angle applies numerical integration in order to calculate effective solid angles, which are further transformed into detection efficiencies. “Calculation precision” is actually the Gauss-Legendre coefficient in numerical integration, i.e. number of segments in the integration interval. The higher it is, the more precise calculation result will be, but the calculation time will be longer.

How high should I set the calculation precision?

You can set any value between 10 and 50. The higher it is – the more precise the result will be, but it will take more time to calculate. Choosing a calculation precision value means optimizing precision vs. calculation time. We recommend values between 25 and 35, because they offer very good precision for most cases, while keeping computation times relatively short. If you use voluminous sources (large cylinders or Marinellis), for example, you may consider using higher precision values.

One should, thus, not exaggerate with calculation precision – it might not tangibly improve your result, while calculation times will be much longer. Try it, if you like, for example 20, 30, and 40 and you will see the effect. On the other hand, setting the precision coefficient too low may produce poor results, while saving only a minute or two on the calculation time.

Ever faster processors, however, make this issue less and less notable.

What is the “Save calculation parameters” option here for?

The “Save calculation parameters” option collects all current parameters (selected detector, container, geometry, source, energies, REC data and calculation precision) and saves it to a file. This is convenient in many cases, such as: when calculations will not be performed immediately, for preparing the calculations which will be performed on another computer or for preparing the inputs for multiple calculations at the same time (batch jobs). Angle 4 allows for a flexible and powerful method of automating multiple calculations, by utilizing its new XML-based file format and command line parameters.

Can I save calculation parameters and use this file for calculations on another computer?

Yes. The saved file contains all the needed information, so it can be used for calculations on any other computer with Angle installed.

I am trying to save the calculation parameters to file, but I am receiving an error message.

Before saving, Angle checks all input values for possible incompatibilities. If there is an incompatibility in input parameters, such as an invalid detector-container combination (for example when using a well detector with a Marinelli container, or when using REC form one detector to perform efficiency calculations with another), the error message will be shown. You should check your input parameters.

What does the output of the calculations means (from what I can see in the output file). How does this output then give me the nuclide concentrations I am looking for?

The output gives you effective solid angles and detector efficiencies for a set of gamma-energies you choose (which means the set of gamma-energies you are interested in with your sample). From efficiencies, the calculation of concentrations is straightforward: there is proportionality between efficiency, number of counts in the particular gamma-peak, activity and concentration.

I changed some parameters of my calculation parameters (detector, container, geometry, source, REC, calculation precision), but I’m still getting the same calculation results!? Why?

Most probably you are performing calculation from files saved prior to the changes you made. If your input parameters are changed after saving the calculation parameters to file(s) the file(s) will still contain the previously defined parameters. Run the calculation from the current data instead, or save the input parameters again and run calculations from newly saved file(s).

I tried to run calculations from file, but I am receiving warning saying that the file is created with a higher version of Angle than the one I am using.

You are trying to run calculations from file created on another computer and you are using Angle with version lower than the one on that computer. Some of parameters specified in this file might be ignored, or misinterpreted.

I am trying to run calculations/save input parameters, but I keep receiving a message that Angle is not registered. Am I doing something wrong?

Unregistered copies of Angle will work in demo mode with all functions enabled, except efficiency calculations (if you are using Angle 4, you will be able to run calculations with demo detectors). In order to unlock the calculations option you must be registered. Please fill in the registration form, using the serial number you got with your copy of Angle and register it using one of the several available methods.

Can we somehow try the calculations in Angle before we decide to obtain licenses?

Yes. Angle 4 comes with a set of eight predefined demo detectors, one for each supported type. You can use them for calculations even in demo mode, i.e. even if Angle is not registered. This way you can evaluate the results, so as to become more familiar with software scope and capabilities – without/before being registered.

Demo detectors are also very useful for educational/training purposes. Now Angle is there for everyone as a free educational/training tool. For example, it can be used for studying the impact of particular parameters characterizing the detection process on the detection efficiency; or, just to experience/train gamma-spectrometry practice.

My calculations are finished and I have got the results. Can I use these results in another application, e.g. spreadsheet or word processing software?

Yes. Just click on the “Copy to Clipboard” button and paste the values in the application you want. This is very convenient for various studies applying Angle output data.

Also, you can export your results directly to ORTEC’s GammaVision or Canberra’s Genie 2000.

We highly recommend this option and we encourage Angle users to take advantage of it, as it opens up new horizons to gamma-spectrometry practice and enhances laboratory performance.

Can I see the parameters used for calculation?

Yes. You can see any input parameter used for calculation. For example, if you want to get information about the detector used, simply click on the detector name or the information button next to it.

Can I print the calculation results?

Yes. If, while viewing the results, you want to print them, just click the “Print calculation results” button to print a one-page document containing the results together with a summary of all the input parameter data, counting arrangement schematics, as well as the calculated efficiency curve (if calculated).

A detailed report can be printed by clicking the “Print calculation report”. The report will contain the results, as well as all the input parameter data used in calculations – thus making the results traceable to the input values.

Can I save the calculation results/report to a document, for example to a PDF?

Yes. The procedure is the same as for regular printing. You just have to choose a virtual PDF printer when printing. If you need help to install PDF printer software, please contact your system’s administrator.

How about traceability of calculation results?

You may notice that a detailed report can be printed by clicking “Print calculation report”. The report contains not only the results, but also all the input parameter data used in the calculations – thus making the results traceable to the input values. This implies that the quality (accuracy) of calculation results depends primarily on the quality (accuracy) of the input parameter data.

If you may wish to gain a better insight into the specific “error propagation” of a particular input parameter (e.g. crystal radius, or dead layer thickness, or source matrix composition...) towards the final calculation result (efficiency), we advise using Angle 4 applicability for research purposes. Suggested reading: [3] in the Literature.

We are working on a study in which we are analyzing the impact of certain input parameters on efficiencies. We have carried out a great many calculations. Can we open all the calculation results files at once?

Yes. Click on the “View calculation results” button on the “Calculations” ribbon tab, select all calculation results files you would like to open and click on the “Open” button. Now you can simply move from one calculation results file to another.

If I send a calculation results file to another computer with Angle installed, can they open it?

Yes.

I am evaluating Angle and I am still using the demo copy. I know that I cannot perform calculations, but can I open a calculation results file from another computer?

Yes. You also have demo output files already installed with Angle – try them.

Can I use my calculation results for efficiency calibration in ORTEC’s GammaVision?

Yes. While viewing output results, click on the “Export to ORTEC GammaVision” button. A new dialog will open where you can choose if you want to export ORTEC GammaVision efficiency calibration file (*.EFT), or geometry correction file (*.GEO). In the latter case you can also specify the uncertainty. After clicking the “OK” button you will have to choose the name and location of the exported file. This file can subsequently be imported in GammaVision.

Can I use my calculation results for efficiency calibration in Canberra’s Genie 2000?

Yes. While viewing output results, click on the “Export to Canberra CAM file” button and choose the name and location of the Genie 2000 CAM file.

I am trying to export calculation results to GammaVision, but the “Export to ORTEC GammaVision” button is disabled.

This is because you calculated only effective solid angles, not efficiencies, which are required by GammaVision. In order to calculate efficiencies, you must specify a reference efficiency curve for your detector.

I am trying to export calculation results to Genie 2000, but the “Export to Canberra CAM file” button is disabled.

This is because you calculated only effective solid angles, not efficiencies, which are required by Genie 2000 In order to calculate efficiencies, you must specify a reference efficiency curve for your detector.

I have successfully run the calculations, hit the “Export to ORTEC GammaVision” button and saved the EFT file. How can I load this file into GammaVision?

Start GammaVision and select the specific detector for which you want to create the new efficiency calibration, using the detector pull-down menu on the toolbar. Next select the option “Calibrate” and then select “Efficiency”. When the “Efficiency Calibration” window opens, click on the white box on the upper left of the sidebar and select “Destroy” from the control menu which will remove any current efficiency calibration data. Then click the “Merge” button, browse for and select the EFT file created by Angle.

At this point it is possible to change the fitting mode for the efficiency data transferred from Angle, as the default fit type is linear, using the “Mode” section of the “Efficiency Calibration” window. Once you have closed the “Efficiency Calibration” window, select “Save Calibration” from the “Calibrate” option and save the new calibration file.

I am trying to import/export calculation results from/to Genie 2000, but I am getting the warning that Genie 2000 is not installed on my computer.

Angle requires Genie 2000 to be installed on your computer to be able to import or export CAM files.

How do I estimate uncertainties of Angle output?

Angle software itself introduces only a negligible level of uncertainty in the calculation result (full-energy peak efficiency). The uncertainty mostly originates from the input data about the detector, source, container, absorbing materials, counting arrangement/geometry, counting statistics (peak area), calibration sources, etc. We estimate that careful application of Angle will produce results not worse than 3-4% for cylindrical and 5-7% for Marinelli sources. There is further suggested reading: [1]-[4] in the Literature.

Can I use Marinelli sources with well detectors?

Even though it is physically possible to count Marinelli sources on well detectors (assuming a Marinelli cavity larger than the detector end-cap), Angle does not support that option; we considered it strange to utilize a highly specialized well detector in just the opposite way as it was conceived/designed for.

Nevertheless, if there is an explicit user’s request for this, such an option can be considered/developed.