The Molière radius is a characteristic constant of a material giving the scale of the transverse dimension of the fully contained electromagnetic showers initiated by an incident high energy electron or photon. By definition, it is the radius of a cylinder containing on average 90% of the shower's energy deposition. Two Molière radii contain 95% of the shower's energy deposition. It is related to the radiation lengthX0 by the approximate relation RM = 0.0265 X0 (Z + 1.2), where Z is the atomic number.[1] The Molière radius is useful in experimental particle physics in the design of calorimeters: a smaller Molière radius means better shower position resolution, and better shower separation due to a smaller degree of shower overlaps.
^Phillip R. Sloan, Brandon Fogel, "Creating a Physical Biology: The Three-Man Paper and Early Molecular Biology"
University of Chicago Press, 2011
^Collaboration, PIONEER; et al. (2022). "Testing Lepton Flavor Universality and CKM Unitarity with Rare Pion Decays in the PIONEER experiment". arXiv:2203.05505 [hep-ex].
^The CMS Collaboration (2006). "Chapter 1. Introduction". CMS Physics : Technical Design Report Volume 1: Detector Performance and Software. CERN. p. 14. ISBN9789290832683. CMS has chosen lead tungstate scintillating crystals for its ECAL. These crystals have short radiation (X0 = 0.89 cm) and Moliere (2.2 cm) lengths, are fast (80% of the light is emitted within 25 ns) and radiation hard (up to 10 Mrad).