Muon Collider Backgrounds

The backgrounds in the detector at a muon collider are recognized as a critical issue for the feasibility of doing physics at this machine. The challenge is to design a final focus system (magnets plus shielding) that will bring the backgrounds down to a reasonable level. The main source of background comes from muon decay. For example, with 2 x 10^12 muons per bunch at a 2 x 2 TeV collider there are 2 x 10^5 decays per meter and the mean energy of the decay electrons is 700 GeV. Fortunately the decay angle of the electrons is very small, which means that electrons born very close to the IP stay in the beampipe untill they are well past the detector region. For those electrons born further away there is room to place sweeping magnets and shielding to reduce the backgrounds they induce in the detector region by many orders of magnitude.

The design of the shielding and final focus is an iterative process, with an evaluation of the detector backgrounds being made at each iteration. Two independent background calculations have been developed: a MARS based calculation (N. Mokhov) and a GEANT based calculaion (I. Stumer). These plus the predicted backgrounds for the final focus design considered at Snowmass 1996 are described in chapter 9 of the Snowmass muon feasibility study report. Since then, further improvements to the final focus have reduced the backgrounds by about an order of magnitude. Although challenging, in many ways the predicted background levels are no worse than the corresponding predicted backgrounds at the LHC .... and we hope for further improvements to the final focus design in the future.

Muon Collider Detector Issues

  • Chapter 9 of the Muon Collider Feasibility Study for the 1996 Snowmass Workshop

  • Backgrounds and Detector Issues at a Muon Collider, S. Geer, FERMILAB-Conf-96/313

    Last updated July 9, 1998
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