EPJ Web of Conferences (Mar 2014)

Kaon Tagging at 0° Scattering Angle for High-Resolution Decay-Pion Spectroscopy

  • Esser Anselm,
  • Achenbach Patrick,
  • Arai Naoki,
  • Gayoso Carlos Ayerbe,
  • Böhm Ralph,
  • Borodina Olga,
  • Bosnar Damir,
  • Bozkurt Vakkas,
  • Debenjak Luka,
  • Distler Michael O.,
  • Friščić Ivica,
  • Fujii Yuu,
  • Gogami Toshiyuki,
  • Rodríguez Mar Gómez,
  • Hashimoto Osamu,
  • Hirose Satoshi,
  • Kanda Hiroki,
  • Kaneta Masashi,
  • Kim Eunhee,
  • Kusaka Junichiro,
  • Maeda Kazushige,
  • Margaryan Amur,
  • Merkel Harald,
  • Müller Ulrich,
  • Nagao Sho,
  • Nakamura Satoshi N.,
  • Pochodzalla Josef,
  • Rappold Christophe,
  • Reinhold Joerg,
  • Saito Takehiko R.,
  • Lorente Alicia Sanchez,
  • Majos Salvador Sánchez,
  • Schlimme Björn Sören,
  • Schoth Matthias,
  • Schulz Florian,
  • Sfienti Concettina,
  • Širca Simon,
  • Tang Liguang,
  • Thiel Michaela,
  • Tsukada Kyo

DOI
https://doi.org/10.1051/epjconf/20146611011
Journal volume & issue
Vol. 66
p. 11011

Abstract

Read online

At the Mainz Microtron hypernuclei can be studied by (e,e’K) reactions. By detecting the kaon which is emitted in forward direction, with the KAOS spectrometer placed at 0° scattering angle, reactions involving open strangeness production are tagged. High-resolution magnetic spectrometers are then used to coincidentally detect the monoenergetic decay-pions from mesonic two-body weak decays of light hypernuclei at rest. As a pioneering experiment has confirmed, the KAOS spectrometer is exposed to a large flux of background particles, mostly positrons from bremsstrahlung pair production. In order to increase the effciency of kaon identification the KAOS spectrometer was modified to suppress background particles at the cost of a high momentum resolution, which is less important for this experiment. This was achieved by placing up to 14 cm of lead absorbers in front of the detectors, in which positrons are blocked by forming electromagnetic showers while the effect on kaons is limited. An additional time-of-flight wall and a new threshold Čerenkov detector help to increase the detection effciency of kaons.