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AESOP and LEE Instruments

AESOP and LEE Instruments. A niti - E lectron S ub- O rbital P ayload. L ow E nergy E lectrons. AESOP and LEE 1999 tandem flight. AESOP departing Esrange 2006. LEE hangtest for Big-60 launch 2002. John Clem and Paul Evenson Bartol Research Institute. NASA grant: NNG05WC08G. Introduction.

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AESOP and LEE Instruments

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  1. AESOP and LEE Instruments Aniti-ElectronSub-OrbitalPayload LowEnergyElectrons AESOP and LEE 1999 tandem flight AESOP departing Esrange 2006 LEE hangtest for Big-60 launch 2002 John Clem and Paul Evenson Bartol Research Institute NASA grant: NNG05WC08G

  2. Introduction Solar modulation is the result of magnetic field fluctuations in the solar wind, scattering cosmic rays out of the solar system and/or decelerate them. Observations have shown cosmic ray electrons and nuclei respond differently to solar modulation, with the differences clearly correlated to reversals of the solar magnetic field, occurring every eleven years. Measurements of positrons, relative to negative electrons allows for a definitive separation of the effects due to charge sign from the other possible effects. The primary goal is quantify these effects through a serials of observations using the same instrument and applying the resulting constraints to heliospheric propagation models.

  3. Reversals of the solar magnetic field occur every 11 years. q>0 q<0 q>0 q<0 Drift Directions Outward flowing solar wind and solar rotation produce a spiral geometry of the interplanetary magnetic field lines. A+ is shorthand for the case where the dipole has a positive projection on the solar rotation axis is positive whereas the opposite projection is termed A-. Particles moving on a curved magnetic field line experience a centrifugal force due to the field curvature that makes the guiding center drift perpendicular to both the centrifugal force and B -- either toward or away from neutral current sheet depending on the particle charge sign and polarity epoch.

  4. LEE A series of balloon observations of electrons with the LEE begun in 1968 at the University of Chicago and has continued at the Bartol Research Institute since 1984. The data from these balloon flights have been used to study solar modulation of electrons with energies up to ~ 20GeV. Flight Log for LEE

  5. Time profile of helium and electron fluxes at a rigidity of ~1.2 GV: Magnetic Polarity 1.2GV Electrons 1.2GV Helium Open Symbols Filled Symbols Response of electrons and nuclei to changing conditions in interplanetary space is qualitatively similar but quantitatively different. Fluxes are low when the sun is active and high when the sun is inactive, however particles with opposite sign to the polarity state reveal a narrower time profile than those with like charge-sign. The electron profile in the 1990s seems to be broader than the helium spike profile observed in the 1980s possibly due to positron component in the electron observations.

  6. AESOP The AESOP instrument was designed and built specifically for this goal… To measure the positron abundance in electrons from 200MeV to 5GeV over a full 22 year cycle. (Chickens can fly) AESOPdetects electrons with plastic scintillators (T1, T3), anticoincidence)(G) and a gas Cherenkov detector (T2). It measures the electron energy in a lead glass (T5) calorimeter. A final scintillator (T6) assists in particle identification and energy determination by counting the number of particles that escape the calorimeter. A permanent magnet and a digital optical spark chamber hodoscope (SC 1,2,3) determine the charge sign and momentum of the electrons.

  7. AESOP 2006 Flight Trajectory Vertical axis: Energy measured in the Pb-Glass calorimeter Horizontal: Deflection in the magnet in units of inverse rigidity. Curve represents the ideal instrument response for positrons (positive side) and electrons (negative side). Red symbols are events tagged as high energy protons Particle ID and energy of each event are assigned using a likelihood analysis

  8. Time dependence of positron abundance (black) and anti-proton ratio (red) at a rigidity of roughly 1.3GV. Black line is a Positron abundance prediction based on the analysis of Clem et al. (1996). Red line is an antiproton/proton ratio model Bieber et al. (1999). Dashed lines are the predicted results for future observations. Anti-protons were measured by the series of BESS flights

  9. Possible Futures for AESOP and LEE We will propose to re-fly LEE and AESOP in 2009 and 2010 One of these proposed flights would involve LEE on LDB 60mcf At some point, we hope to replace the spark chamber hodo-scope with a lighter system which would allow higher altitude flights. Check out the website http://www.bartol.udel.edu/~balloon/ for further details

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