A modified QDD spectrometer for η meson decay measurements

A. Moalem, F. Meot, G. Leleux, J. P. Penicaud, A. Tkatchenko, P. Birien

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


We propose a modified structure of a QDD spectrometer for studying rare andforbidden decay modes of the eta metal. Such a modified structure is based on replacing the quadrupole with a special magnet which provides a quadrupole field along the spectrometer axis and two dipolar field zones extending below and above the beam axis for momentum analyses of decay particles. Particularly, a modified structure of the spectrometer SPES II, that has been in use at the LNS and CERN for more than a decade, is presented. First order and ray-tracing calculations show that the beam optics and momentum resolution of such a modified structure are of a comparable quality to those of the SPES II. In addition, the intrinsic resolution of the special magnet as a momentum analyzer is well below 0.5% and can be realized if the longitudinal extension of the object (reaction vertex) is limited to ±5 mm and its transverse extension (beam spot on target) to ±2 mm.

Original languageEnglish
Pages (from-to)168-175
Number of pages8
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Issue number1-2
StatePublished - 1 Apr 1990
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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