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Studies to be done with the Aluminium and/or Silver target in place of the AK3

The main purpose of these systematic runs will be to determine the effect of detector inefficiencies in pulling the lifetime.

Central Position

  • No applied magnetic field
    • This can be used to simulate the effect of stopping muons in a near zero field region in the normal AK3 target.
    • Since the muon should remain mostly polarized, and the rotation during measuring will be minimal, there will be a large 7:5 difference in count rates between upstream and downstream detectors.
    • The slow rotational effect is expected to give a rather large asymmetry (Simulation indicates a difference in tau of 10 ns or ~0.5%).
    • But the summed value (assuming good efficiencies) should be consistant with the measured value from the main data set.
    • If we assume the observed asymmetry is 50 ppm, the simulation would suggest that this could come from 1/100 muons stopping in this low field region.
      • To get a 1% measurement of the lifetime asymmetry would require 2e9 muons per side.
      • This means 4e9 muons total or about ~20 ppm measurement.
      • This should constrain this effect to about the 0.2 ppm level.
      • This requires about 4 hours of running.
  • Applied magnetic field
    • This allows us to artificially add a T2 component by creating a relatively inhomogenous field.
    • In addition, we don't really expect muons to experience earth's magnetic field so this gives a second measurment of the irregular stops in the target.
    • The size of the field still needs to be determined. Is a low field desired, or do we want a larger field so that we can probe the effect of T1. If a high enough field is used, the detector efficiencies could be measured directly by integrating over several periods.
    • Same estimate on desired statistics as above: ~4 hours of run time.

Off Center Position

  • I havn't given this a whole lot of thought, but my idea here would be to apply a large enough field that several oscillation periods are observed allowing for a measurement of the efficiency difference at a different location. Then, we can compare the summed lifetime difference and extract the dependance on effective detector efficiency.

-- DanChitwood - 14 Sep 2006

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Topic revision: r1 - 2006-09-14 - DanChitwood
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