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electron/positron background flux models

electron/positron background flux models. October 14, 2003 Tsunefumi Mizuno mizuno@SLAC.Stanford.EDU. Background flux model functions for e-/e+ in CRflux package are given here. The model is under construction and the function shown in this report could be modified in future. Plan overview.

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electron/positron background flux models

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  1. electron/positron background flux models October 14, 2003 Tsunefumi Mizuno mizuno@SLAC.Stanford.EDU Background flux model functions for e-/e+ in CRflux package are given here. The model is under construction and the function shown in this report could be modified in future. CRflux_electronPositron_2003-10-14.ppt

  2. Plan overview • The background flux depends on satellite position (due to geomagnetic cutoff) and year (due to solar activity). To take these effects into account for primary component, we utilize the formula similar to those of proton and alpha. There, solar modulation potential and cutoff rigidity are included in the function explicitly. • We refer to the AMS data (Alcaraz et al. 2000, Phys. Let. B 484, 10) and model the flux spectra with analytic functions. CRflux_electronPositron_2003-10-14.ppt

  3. electron model functions • Reference: • Data compilation in Komori et al. 1999, proceeding of large balloon symposium at ISAS, p33. (The same data points are also given in Kobayashi et al. 1999, proceeding of 26th ICRC 3, p61). Spectrum for all electrons(e- + e+) is given here. • Golden et al. 1996, ApJL 457, 103; assume that positron fraction is 0.078 • Solar modulation theory (L. J. Gleeson and W. I. Axford 1968, ApJ 154, 1011) • Etc. • Model functions: • Primary: Power-law with solar modulation effect (Gleeson and Axford 1968)and geomagnetic cutoff (introduced by T. Kamae and M. Ozaki to reproduce low geomag. lat. proton data of AMS). • Secondary:Simple analytic functions such as power-law. Model functions are determined to reproduce the AMS data. Below 100 MeV, we do not have AMS data and we just extrapolate the spectrum down to 10 MeV with E^-1. To keep the model simple, we use the same function to express the reentrant (downward) and splash (upward) spectra. [c/s/m^2/sr/MeV] CRflux_electronPositron_2003-10-14.ppt

  4. positron model functions • Reference: • Model functions for electron primary. • Golden et al. 1996, ApJL 457, 103 • Etc. • Model functions: • Primary: We adopted the results of Golden et al. (1996) and assume that a fraction fraction is 0.078 (energy indepent). • Secondary: Like for electrons, we utilize Simple analytic functions such as power-law. [c/s/m^2/sr/MeV] CRflux_electronPositron_2003-10-14.ppt

  5. Note for primary spectra We have utilized the data compilation in high energy region (100 GeV-10 TeV) and modeled the interstellar electron spectra as 0.667*E^-3.33. This function givse a slightly higher flux in relatively low energy region (around 10 GeV), as shown in figure below. We can also see that the interstellar spectrum of primary electron could not be a single power-law, but suffers a small cutoff in low energy region (below 2-3 GeV). Interstellar spectrum of primary electron. Three observations shown here were in similar solar activity, and we demodulated their data according to equation in page 3 with phi=650 MV. Unmod=0.667*E^-3.33 references; J. Alcaraz et al. 2000, Phys. Let. B 484, 10 Boezio et al. 200, ApJ 532, 653 Golden et al. 1994, ApJ 436, 769 CRflux_electronPositron_2003-10-14.ppt

  6. e-/e+ models (1) Vertically downward going e-/e+ flux data by AMS (geomagnetic latitude theta_M<0.3; geomagnetic equator) and model functions. phi=650 MV Rc=12.7 GV 2ndary electron 2ndary positron (E<100 MeV) (E<100 MeV) (E=0.1-2 GeV) (E=0.1-20 GeV) (E=2-20 GeV) CRflux_electronPositron_2003-10-14.ppt

  7. e-/e+ models (2) Vertically downward going e-/e+ flux data by AMS (0.3<theta_M<0.6) and model functions. phi=650 MV Rc=8.7 GV 2ndary electron 2ndary positron (E<100 MeV) (E<100 MeV) (E=0.1-20 GeV) (E=0.1-20 GeV) CRflux_electronPositron_2003-10-14.ppt

  8. e-/e+ models (3) Vertically downward going e-/e+ flux data by AMS (0.6<theta_M<0.8) and model functions. phi=650 MV Rc=4.5 GV 2ndary e-/e+ (E<100 MeV) (E=0.1-20 GeV) CRflux_electronPositron_2003-10-14.ppt

  9. e-/e+ models (4) Vertically downward going e-/e+ flux data by AMS (0.8<theta_M<0.9) and model functions. phi=650 MV Rc=2.5 GV 2ndary e-/e+ (E<100 MeV) (E=0.1-20 GeV) CRflux_electronPositron_2003-10-14.ppt

  10. e-/e+ models (5) Vertically downward going e-/e+ flux data by AMS (0.9<theta_M<1.0) and model functions. phi=650 MV Rc=1.5 GV 2ndary e-/e+ (E<100 MeV) (E=100-300 MeV) (E=0.3-20 GeV) CRflux_electronPositron_2003-10-14.ppt

  11. e-/e+ models (6) Vertically downward going e-/e+ flux data by AMS (1.0<theta_M<1.1) and model functions. phi=650 MV Rc=0.8 GV 2ndary e-/e+ (E<100 MeV) (E=0.1-20 GeV) CRflux_electronPositron_2003-10-14.ppt

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