DIRAC: A High Resolution Spectrometer for Pionium Detection

TL;DR

The DIRAC spectrometer at CERN is designed to detect pionium atoms with high resolution, overcoming challenges of high interaction rates and low relative momentum detection to study pion pairs.

Contribution

This paper introduces the design and performance of the DIRAC spectrometer, a novel high-resolution apparatus for pionium detection at CERN.

Findings

Successful commissioning of the spectrometer at CERN

Achieved measurement resolution around 0.6 MeV/c

Effective trigger and data acquisition systems implemented

Abstract

The DIRAC spectrometer has been commissioned at CERN with the aim of detecting $\pi^+ \pi^-$ atoms produced by a 24 GeV/$c$ high intensity proton beam in thin foil targets. A challenging apparatus is required to cope with the high interaction rates involved, the triggering of pion pairs with very low relative momentum, and the measurement of the latter with resolution around 0.6 MeV/$c$. The general characteristics of the apparatus are explained and each part is described in some detail. The main features of the trigger system, data-acquisition, monitoring and setup performances are also given.