Precision measurement of the boron to carbon ratio in cosmic rays with AMS-02

A precision measurement of the Boron to Carbon ratio in cosmic rays is carried out in the range 1 GeV/n to 670 GeV/n using the first 30 months of flight data of AMS-02 located on the International Space Station. Above 20 GeV/n, it is the first accurate measurement. About 5 million clean Boron and Carbon nuclei are identified. The experimental and analysis challenges in achieving a high precision measurement are addressed. Boron is exclusively produced as a secondary particle by spallation from primary elements like Carbon in collisions with interstellar medium. The unprecedented precision and energy range of this measurement deepen the knowledge of cosmic ray propagation. Using this measurement, the diffusion coefficient in Gal-Prop model is determined to be (6.05 ± 0.05)10 28 cm2/s, and the Alfven velocity is (33.9 ± 1.0) km/s. This makes the prediction of secondary anti-proton background in dark matter search one order of magnitude more accurate.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2015

Author dc:creator

• Sun, Wei, Ph. D. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• Ulrich J. Becker.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/99244

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/99244