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A Search for Massive Magnetic Monopoles at the Baksan Underground Scintillation Telescope

A Search for Massive Magnetic Monopoles at the Baksan Underground Scintillation Telescope. Yu.F. Novoseltsev, M.M. Boliev, A.V. Butkevich, S.P.Mikheev, V.B. Petkov. Institute for Nuclear Research of RAS. Pylos - 2004. The experiment has been performed for both fast ( β ≥ 0.4) and slow

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A Search for Massive Magnetic Monopoles at the Baksan Underground Scintillation Telescope

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  1. A Search for Massive Magnetic Monopoles at the BaksanUnderground Scintillation Telescope Yu.F. Novoseltsev, M.M. Boliev, A.V. Butkevich, S.P.Mikheev, V.B. Petkov Institute for Nuclear Research of RAS Pylos - 2004

  2. The experiment has been performed for both fast (β ≥ 0.4) and slow (2×10-4≤ β≤ 10-1) monopoles. In the velocity range β ≥ 0.4, we made use of "the cascade trigger" (large energy deposition in the facility), the time-flight method was used for 2×10-4 ≤ β ≤ 10-1 range. BUST is located at the depth of 850 m w.e. The facility dimensions are 17×17×11 m3. • The “slow trigger” requires of internal plane operation SΩ = 1850 m2×sr (isotropic flux) • The β ≥ 0.4 trigger requires crossing of three horizontal planes SΩ = 728 m2×sr (isotropic flux) Pylos - 2004

  3. 210-4 < β < 0.1 • “in 1” means 6 external planes • “in 2” is 2 internal planes • Trigger rate is ≈ 200 per day Pylos - 2004

  4. Trigger is the coincidence of the signal from one of external planes with the internal plane signal delayed greater than 50 ns. • Live time = 127630 hours = 14.56 years (01.1982 − 01.2000) • Only events with three hit planes were considered as slow particle candidates (because a background from stopping of muons with subsequent μ - e decay was rather large) Pylos - 2004

  5. All triggered events can be subdivided into 3 groups: • 44 % − μ-e decays • 54.6 % − random coincidence • 1.4 % − relativistic muons which have flight time > 50 ns (large zenith angles θ ≥ 80o) No candidate for the slow particles was recorded FMM≤ 3.2 ×10-16 cm-2s-1sr-1 (90 % CL)

  6. β≥ 0.4, q ≥ 137/2e • The events were selected in which the energy deposition in the facility exceeded εth = 1540 r.p. = 77 GeV (1 r.p. = 50 MeV) • To estimate the light yield (dL/dx) in a scintillator we use the expression (Salamon, Ahlen, 1981) (1) where dE/dx is the total energy loss, A = 0.03, B is the quenching parameter, F is the fraction of energy loss which results from excitations outsite the core. Pylos - 2004

  7. Some characteristics of BUST and MACRO scintillators • In passing of MM through the BUST, the energy deposition ε > εth/4 = 385 r.p. should be observed in each of planes intersected byMM (this value (εth/4) determines the least velocity of MM (β ≈ 0.4)) • The energy deposition have to be the undamped one in contrast to the cascade Pylos - 2004

  8. β≥ 0.4 • Live time = 35400 hours • No candidate for theundamped energy deposition was obtained FMM≤ 2.5 ×10-15 cm-2s-1sr-1 (90 % CL) Pylos - 2004

  9. Pylos - 2004

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