User:Sophie/CE

Channel Description

CE stands for Conversion Electron. This is the primary signal we are searching for at Mu2e. Therefore, ensuring an accurate generator is crucial to us understanding what our signal could look like in our detectors.

Literature

• R. Szafron: https://inspirehep.net/files/ca391cf43844ae4f84155c354c510260 describes the leading log corrected spectrum we use in Mu2e/Offline and Production.

Generator

Conversion electrons can be generated in two ways:

• as endpoints (CEEndpoint) assuming a coherent mono-energetic electron emitted at 104.97 MeV/c
• including leading log radiative corrections (see literature).

In the latter case are 10 % of the electrons are in a low momentum tail shifted away from the endpoint.

In the figure below we see the generated spectra for the two cases on a log scale:

Functional Forms

The CeEndpoint is a simple delta function at the 104.97 MeV/c endpoint for coherent conversion in an aluminum nucleus.

The endpoint energy is calculated as follows:

with muon mass of 105.66 MeV/c^2 and E_(BE,1s) is the binding energy of the 1s state, and E_{recoil} denotes the nuclear recoil energy.

The leading log corrections are derived in the literature noted above:

.

where most of the terms have their usual meaning and Emax is the conversion energy and W (Ee) is the non-universal part of the correction.