Strangelet Search in Lunar Soil

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Strangelet Search in Lunar Soil

• Ke Han
• Evan Finch
• 12/15/2004

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Strangelets 54O Density in Lunar Soil

• Assuming
• 1 event in 4.6 days in 0.167 m2 sterad for
  AMS-01.
• AMS-01 can only count strangelet events with
  Betagt0.4.
• Exposure age to strangelet flux of moon is 500M
  years.
• Strangelet penetrating distance is 1m on average.
• The ratio 54O/16O on the moon is 4.410-17
• Jes Madsens theoretical calculation 2.310-17
  agrees with this number roughly.

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Strangelets 54O Density in Lunar Soil

• This ratio is 105 smaller than what we thought,
  because we neglected the solar modulation before.
• When extending AMS-01 events with Betagt0.4, Jes
  Madsens new theory considering solar modulation
  gives only 10-40 gain for the range Betagt0. Our
  previous calculation gave a gain about 105.

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Running Time

• Assuming
• 16O Beam Current in the Accelerator is 6uA.
• The beam transmission efficiency through the
  accelerator is about 20.
• For each magnet setting, the accelerator covers
  1/14 amu.
• We can get
• The 16O flux that will arrive at the detection
  system is 7.2 X 1012 ions / second.
• For an hour run, we have 1.1 strangelets.
• Running for 5 hours for each magnet setting to
  get about 5-6 strangelets.
• Suppose strangelet isotopes other than 54O exist,
  we need only cover 2 amu thoroughly. Thats 140
  hours running time.
• Or we would like to cover the whole Delta Range
  (548/-6), we need 980 hours.

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Experiment Setup

• Gold Foil Two different choices10um and 12um
• dE Counter 8.2um Si layer with front Au window
  (20nm) and rear Al window (150nm)
• E Counter Si layer should thicker than 18.1um so
  it can absorb all the energy.

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Measurement Procedure
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Measurement Procedure
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Measurement Procedure
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Measurement Procedure
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Measurement Procedure
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Background Beam Current

• Considering about the source ratio in lunar soil,
  ion source sputtering efficiency, and charge 5
  stripping efficiency, we get the background beam
  current in the accelerator, assuming 16O
  current6uA.
• The background beam current is useful for our
  calibration run.
• They wont survive after the rigidity-selection
  magnets and Gold foil.

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Background Ions in the E-dE Plot
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Background Ions in the E-dE Plot

• Two strangelets with 85 MeV (stripped charge 4)
  and 102 MeV (stripped charge 5) before the Gold
  foil.
• Normal Oxygen with different incident energy fall
  near strangelets.
• Oxygen accelerated from lunar soil will not have
  right rigidity to cross the magnets and then will
  not appear in E-dE plot.
• The only concern about the background is the
  pick-up ions, that is, ions produced from the
  collision between the beam and gas in the
  accelerator.