Obtaining a History of the Flux of Cosmic Rays using In Situ Cosmogenic $^{14}$C Trapped in Polar Ice

• Main Authors: BenZvi, Segev, Petrenko, Vasilii V., Hmiel, Benjamin, Dyonisius, Michael, Smith, Andrew M., Yang, Bin, Hua, Quan
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2019
• Subjects: High Energy Astrophysical Phenomena astro-ph.HE; Instrumentation and Methods for Astrophysics astro-ph.IM; FOS Physical sciences; ice core
• Online Access: https://dx.doi.org/10.48550/arxiv.1909.07994; https://arxiv.org/abs/1909.07994

Carbon-14 ($^{14}$C) is produced in the atmosphere when neutrons from cosmic-ray air showers are captured by $^{14}$N nuclei. Atmospheric $^{14}$C becomes trapped in air bubbles in polar ice as compacted snow (firn) transforms into ice. $^{14}$C is also produced in situ in ice grains by penetrating cosmic-ray neutrons and muons. Recent ice core measurements indicate that in the $^{14}$CO phase, the $^{14}$C is dominated by the in situ cosmogenic component at most ice coring sites. Thus, it should be possible to use ice-bound $^{14}$CO to reconstruct the historical flux of cosmic rays at Earth, without the transport and deposition uncertainties associated with $^{10}$Be or the carbon cycle uncertainties affecting atmospheric $^{14}$CO$_2$. The measurements will be sensitive to the cosmic-ray flux above the energy range most affected by solar modulation. We present estimates of the expected sensitivity of $^{14}$CO in ice cores to the historical flux of Galactic cosmic rays, based on recent studies of $^{14}$CO in polar ice. : Presented at the International Cosmic Ray Conference (ICRC2019) in Madison, WI, USA, July 2019. 8 pages, 2 figures