# Energy scale calibration of KEDR detector tagging system

## TL;DR

This paper details the design and current status of the energy scale calibration system for the KEDR detector's tagging system, utilizing two methods to ensure precise measurement of scattered electron energies in two-photon process studies.

## Contribution

It introduces a dual-method calibration approach for the KEDR detector's tagging system, enhancing energy measurement accuracy for small-angle scattered electrons.

## Key findings

- Calibration methods achieve high energy resolution
- System ensures precise energy scale calibration
- Current calibration status is documented

## Abstract

The tagging system of the KEDR detector is a symmetrical focusing magnetic spectrometer for electrons and positrons scattered at small angles; it is embedded into the lattice of the VEPP-4M collider and intended for two-photon processes study. It measures scattered electron energy with resolution $\Delta E/E_0=0.03\%...0.6\%$ ($E_0$ is the beam energy). For precise energy scale calibration two methods are used: tagging of bremsstrahlung electron/positron by the photon energy measured by BGO calorimeter, and direct calibration using Compton backscattering spectrum edge. This report covers design and current status of the calibration system.