How Do We Interpret the Isodose Contours of HERMES III?

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SUMMARY

The forum discussion focuses on interpreting the isodose contours generated by the HERMES III gamma-ray facility, specifically examining the effects of varying anode-cathode gaps of 53, 70, and 87 cm. The isodose maps, created using UNIRAS graphics software, illustrate symmetrical radiation patterns around the z-axis, with gamma rays extending up to 1000 cm (approximately 33 feet) in length and 800 cm (26 feet) in width. The last image in the series shows a larger radius due to beam divergence, starting at 1250 cm, which raises questions about the accuracy of the radius and z-axis measurements compared to the previous images.

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Rev. Cheeseman
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How to interpret the isodose contours?
These pictures below show four isodose contours of HERMES III with different anode-cathode gaps. The radiation produced are gamma rays. More informations can be seen here in the article https://www.osti.gov/biblio/6233581...-simulation-technology-laboratory-guide-users

HERMES III isodose contour map 1.PNG

HERMES III isodose contour map 2.PNG

HERMES III isodose contour map 3.PNG

HERMES III isodose contour map 4.PNG

According to the description which you can see somewhere in the article, it said "The series of maps in Fig. 6 illustrate isodose contours for AK gaps of 53, 70 and 87 cm both in the indoor cell and the outdoor cell. The patterns are symmetrical about an axis perpendicular to the center of the faceplate (defined as the z axis) and can be viewed as being in either a horizontal or vertical plane. The TLD data from which these maps were drawn, by a UNIRAS graphics software package, is stored in the STL VAX 11/780 and can be manipulated to illustrate the radiation contours in a variety of ways. For example, cross-sections at various z-axis locations, three-dimensional representations, and enlargements of any particular region can be generated. Representative illustrations of these possibilities are shown in the series of plots in Fig. 7."

My question is how do we interpret the isodose contours above? Is there anyone here who work with Sandia National Labs? If I have to interpret the pictures, judging by the Radius and Z-axis in cm, the gamma rays extend to 1000 cm which is equal to approximately 33 feet long and the radiation width is 800 cm which equal to 26 feet wide especially in the first three pictures. But I'm confused about the last picture, is the radius and z-axis correct? Compare to the previous three pictures, the gamma radiation at the last picture seems to be very huge and also seems to be zoomed in. English is not my first language so I'm sorry. Thoughts?
 
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wonderingchicken said:
Summary:: How to interpret the isodose contours?

But I'm confused about the last picture, is the radius and z-axis correct? Compare to the previous three pictures, the gamma radiation at the last picture seems to be very huge and also seems to be zoomed in.

The isodose plot of the last figure in for the outdoor irradiation area. Note that it starts at 1250 cm which is the wall next to the indoor irradiation area which is about 1220 cm from the exit port of the accelerator. The larger radius is due to the divergence of the beam.
 

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