1 / 24

Calculating the Flux of Solar Neutrinos

Calculating the Flux of Solar Neutrinos. By: Carrie A. Gill Advisors: Dr. Andrea Erdas & Dr. Mary Lowe CS AAPT Conference November 5, 2005. Outline. Subatomic Particles & Forces Solar Properties Solar Neutrino Problem Formulas Results & Conclusion References.

tieve
Télécharger la présentation

Calculating the Flux of Solar Neutrinos

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Calculating the Flux of Solar Neutrinos By: Carrie A. Gill Advisors: Dr. Andrea Erdas & Dr. Mary Lowe CS AAPT Conference November 5, 2005

  2. Outline • Subatomic Particles & Forces • Solar Properties • Solar Neutrino Problem • Formulas • Results & Conclusion • References

  3. SUBATOMIC PARTICLES & FORCES

  4. Forces • Gravitational Force • Electromagnetic Force • Strong Force • Weak Force

  5. Forces- Short Range • Strong Force ← - binds quarks inside neutrons and protons - binds nuclei together - cannot change quark type • Weak Force → - changes one type of quark into a different type - responsible for beta decay - n → p + e- + νe-

  6. Neutrinos • 3 types of neutrinos and 3 types of anti-neutrinos • Thought to be massless (still controversial) • No electric charge • Only produced by the weak force • Only interact through the weak force • Stable, fundamental particles About 1 trillion neutrinos pass through your thumb every second!!!

  7. Neutrino Production • Produced in nuclear fusion reactions in the solar core • Exit Sun in about 2 seconds • Almost never interact with other particles in space or in our atmosphere • Can be painstakingly detected on Earth • Flux can provide current information about the solar interior and nuclear reactions!!

  8. SOLAR PROPERTIES

  9. Standard Solar Model (SSM) • Begins with homogeneous composition • Solar core is modeled as an ideal plasma • Hydrogen burning- supplies luminosity and pressure to balance gravity • Energy is transported by photons • Chemical composition slowly changes with nuclear reactions

  10. Reaction Chains • Proton- Proton Chain - overall: 4p → 1He + 2e+ + 2ve + 25 MeV - reactions produce larger atoms - includes sub-chains involving 7Be and 8B - accounts for 99.6% of the Sun’s energy • CNO Cycle - accounts for 0.4% of the Sun’s energy - occurs more often in older stars

  11. SOLAR NEUTRINO PROBLEM

  12. Predicting Neutrino Flux • correct and complete→ able to predict the amount of neutrinos hitting Earth from the Sun • prediction is wrong→ either SSM incorrect or new physics

  13. Neutrino Detectors • Located almost 1 mi underground • Used 100,000 gallons of tetrachloroethylene (C2Cl4) • 37Cl + ve→ 37Ar + e- • Total number of 37Ar atoms collected reflects flux of neutrinos Homestake Gold Mine Neutrino Experiment

  14. Solar Neutrino Problem • Observed flux ≈ predicted flux for low energy neutrinos (PP) • Observed flux << predicted flux for high energy neutrinos (7Be, 8B) • There is some other source of power in the Sun • Scientists calculated the reaction rates inaccurately • Evidence that neutrinos can change “type” en route to Earth (detectors can only detect one type)

  15. FORMULAS

  16. Summary of Equations: Maxwell-Boltzmann Maxwell-Boltzmann Distribution

  17. Tsallis Distribution • Changed the normalized energy distribution from Maxwell-Boltzmann to Tsallis • Vary parameter empirically to match known data

  18. Change in Equation

  19. RESULTS & CONCLUSION

  20. A Comparison • pp neutrino flux using the Maxwell-Boltzmann distribution • total flux = 6.2 X 1010 cm-2 s-1 4x1012 2x1012 dFlux/d(R/R0) cm-2 s-1 • Bahcall’s value for pp neutrino flux = 6.0 X 1010 cm-2 s-1

  21. PP- Maxwell-Boltzmann vs. Tsallis Neutrino Production as a function of Solar Radius Maxwell-Boltzmann 5x1012 4x1012 3x1012 2x1012 1x1012 Tsallis: δ=0.0005 Tsallis: δ=0.0018 dFlux/d(R/R0) cm-2 s-1 Φ(δ=0.0018)=6.004 X 1010 cm-2 s-1 R/R0

  22. What Now? • Find flux for neutrinos from other reactions using the Tsallis distribution • Vary parameter (δ) so that predicted data matches observed data • Check that the Tsallis model using the parameter’s value still yields a close result for the pp reaction • Implies that the Sun’s core is not an ideal plasma (although it is very close)

  23. REFERENCES

  24. References • Neutrino Astrophysics by: John N. Bahcall • Principles of Stellar Evolution and Nucleosynthesis by: Donald D. Clayton • Cauldrons in the Cosmos- Nuclear Astrophysics by: Claus E. Rolfs & William S. Rodney • Quantum Physics of Atoms, Molecules, Solids, Nuclei, & Particles by: Robert Eisberg & Robert Resnick • A Tour of the Subatomic Zoo- A Guide to Particle Physics by: Cindy Shwarz • The Discovery of Subatomic Particles by: Steven Weinberg • Programming with Fortran 77 by: William E. Mayo & Martin Cwiakala • Numerical Recipes in Fortran 77 by: Flanney, Press, Teuolsky, & Vetterling

More Related