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 length X0 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.
The Molière radius is named after German physicist Paul Friederich Gaspard Gert Molière (1909–64). [2]
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).
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 length X0 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.
The Molière radius is named after German physicist Paul Friederich Gaspard Gert Molière (1909–64). [2]
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).