Rotating detector or spectrometer to measure differential cross sections (angular distributions) in fixed-target experiments.
| Rotating detector or spectrometer to measure differential cross sections (angular distributions) in fixed-target experiments. |
For colliding beams only the
total cross section can be measured and the detector arrays
surround the collision region insofar as is possible. (For
obvious reasons a cylindrical geometry is generally adopted!)
Below is a model of the Atlas detector at the LHC. Note
human figures for scale.
A differential cross section,
protons on 58Ni nuclei, elastic scattering.
The standard unit for cross sections is the millibarn (mb),
which is equal to 0.1 fm2, with a fm being 10-15
m. Physicists refer to a fm as a Fermi, but its technical name
is femtometer. I am hoping you know what a steradian
is!
