  Cosmic ray muons present a large part of the radiation background and
depending on the application of interest muons can be seen as background noise,
e.g., radiation mapping, radiation protection, dosimetry, or as a useful
interrogation probe such as cosmic ray muon tomography. It is worth noting
recent developments on muon scattering tomography which has emerged as a
prospective noninvasive monitoring method for many applications including spent
nuclear fuel cask monitoring and geotomography. However, it is still very
challenging to measure muon momentum in the field, despite the apparent
benefits, without resorting to large and expensive calorimeters, ring imagers,
or time of flight detectors. Recent efforts at CNL and INFN have developed
large prototypes based on multiple Coulomb scattering coupled with the muon
momentum reconstruction algorithms. While these efforts show promise, no
portable detectors exist that can measure muon momentum in the field. In this
work, we present a new concept for measuring muon momentum using coupled
pressurized gaseous Cherenkov radiators. By carefully selecting the gas
pressure at each radiator we can optimize the muon momentum threshold for which
a muon signal will be detected. This way, a muon passing through the radiators
will only trigger those radiators with momentum threshold less than the actual
muon momentum. By measuring the presence of Cherenkov signals in each radiator,
our system can then estimate the muon momentum. The primary benefit of such a
concept is that it can be compact and portable enough so that it can be
deployed in the field separately or in combination with existing tomography
systems.
