Solar Modulation of Protons and Helium in Cosmic Rays with the Alpha Magnetic Spectrometer
| dc.contributor.author | Corti, Claudio | |
| dc.contributor.department | Physics | |
| dc.date.accessioned | 2019-05-28T20:28:30Z | |
| dc.date.available | 2019-05-28T20:28:30Z | |
| dc.date.issued | 2017-08 | |
| dc.description.abstract | The search for the local interstellar spectrum (LIS) of galactic cosmic rays (GCRs) and a full understanding of their propagation in the heliosphere are long-standing issues in the field of cosmic rays (CRs) and heliophysics. In recent years, the increasing precision of direct CR measurements lead to many advancements in different fields, such as acceleration and propagation processes of CRs in the galaxy and high-sensitivity indirect searches of dark matter. The study of how GCR fluxes change in time is also fundamental from the technological point of view: future human missions in deep space will require better predictions of radiation doses received by astronauts and electronics due to the long-term exposure to GCRs. The Alpha Magnetic Spectrometer (AMS) experiment, on board the International Space Station (ISS) since May 2011, is measuring with unprecedented accuracy the fluxes of GCRs from 0:5 GeV=n up to a few TeV=n. The large acceptance of AMS allows to perform a detailed study of the time variation of GCRs during an entire solar cycle, improving the understanding of the interplay between the different solar modulation processes. In this work, AMS data have been analyzed to produce a very precise measurement of the monthly proton and helium fluxes. A new parametrization of the proton and helium LIS has been derived, based on the latest data from Voyager 1 and AMS. Using the framework of the forcefield approximation, the solar modulation parameter is extracted from the time-dependent fluxes measured by PAMELA, BESS and AMS. A modified version of the force-field approximation with a rigidity-dependent modulation parameter is introduced, yielding better fits than the force-field approximation. A comprehensive 3D steady-state numerical model is used to solve the Parker transport equation of GCRs in the heliosphere and to reproduce the proton monthly fluxes observed by AMS. The limitations of this approach in describing the modulation processes during the maximum of solar activity are discussed. | |
| dc.identifier.uri | http://hdl.handle.net/10125/62677 | |
| dc.language | eng | |
| dc.publisher | University of Hawaii at Manoa | |
| dc.subject | Galactic cosmic rays | |
| dc.subject | Cosmic rays--Measurement | |
| dc.subject | Solar oscillations | |
| dc.subject | Magnetic spectrometer | |
| dc.title | Solar Modulation of Protons and Helium in Cosmic Rays with the Alpha Magnetic Spectrometer | |
| dc.type | Thesis | |
| dc.type.dcmi | Text | |
| dcterms.description | Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017. |
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