MINOS
UCL MINOS Homepage
Back to my MINOS
de/dx difference between +1 and +9 GeV muons
Roy Lee and Sharon Seun state in their paper (NuMI-L-694) that energy deposition by muons as they go through matter (specifically iron-scintillator) goes logarithmically with muon energy. So I'm going to look at some new T7 2003 CalDet data and study some +1 GeV and +9 GeV beam muons. Hopefully I'll find about 8% difference in energy deposition.
The whole range, lots of pions at low energy. Click for root. The bottom right plot is Last Plane Hit (lph). ( 1 GeV )
Cut between planes 20 - 30 to select muons. Click for root.
A gaussian does not fit to this well at all!
Being data, this sample is obviously much less 'clean' than Monte Carlo simulation: the expected lph for a sample of 1GeV and 1.8GeV muons is given.
But further effects should be considered...
Muons are created from the decay of pions as they travel down the beam pipe. If the pion energy as it decays is 2 GeV then the maximum energy of the resulting muon is 2 GeV. In the rest frame of the decaying pion, the muon can be emmitted in the opposite direction to that of the travel of the pion (i.e. facing back down the beam pipe) which would cause a maximum effecive reduction of momentum of the muon by a factor of 0.57.
Based on
Ruben's pion kinematics info
it was possible to construct a more accurate simulation of the expected energy distribution of beam muons at CalDet. It can be seen that there is a large number of muons at energies much lower than nominal. A spread of muon energies of 5% is also included in this plot.
This results in an expected Last Plane Hit distribution as shown. This is not yet a complete description of what we see; the pions that decay upstream of the collimators are not included.
This is the final result for a 1 Gev muon
Results agree well with Ruben's decay turtle simulation.