...
There is already a very detailed Geant4 description of the ATLAS detector used in physics event simulation; however, it is far too complicated for this application. Instead, we will update the validation geometry to be consistent with the full ATLAS description, concentrating on those regions that affect background the most, e.g.
- Beam line and shielding
- Gap between barrel and toroid
- Cavern outline
We will also add the large missing elements such as
...
- Previously missing barrel toroid.
- Barrel muon chambers used to be modeled as cylinders, now modeled as flat packages
- Proper position of endcap muon chambers
The next picture shows the newly implemented barrel toroid, including the struts that hold the coils apart.
Some simplifications will be made, especially detector internal geometries which are important for detector response but not for this application. It is important to maintain the proper isotopic composition of materials as neutron cross sections are sensitive.We will calculate the background for each of these changes individually in order to understand their effects.
Expected radiation levels and counting rates will be compared with data after beam turn-on in late 2009. Differences have to be traced back to possible inaccuracies in the modeling.
...