Recovery of data related to the destruction of ⁷Li and ⁷Be in astrophysical environments

Big bang nucleosynthesis, one of our only probes of the very early universe, gives us predictions for the abundance of old light elements (D, $^3$He, $^4$He). First studied in the early 1940's[1], there remains one alarming issue still unresolved: the predicted abundance of $^7$Li, both directly from BBN and from the immediate decay of $^7$Be formed via BBN, is off by approximately a factor of 3 based on our current observations of the universe[2]. In 2001-2002 a collaboration at the Weizmann Institute in Israel studied reactions that could account for the destruction of $^7$Be or $^7$Li. This data, taken at the VDG laboratory, involved $^3$He beams at energies from 390-1130 KeV on $^7$Be and $^7$Li targets.[3]

While preliminary data analysis was conducted in 2002, a large portion of the data was never analyzed. This data, now 20 years old, could contain valuable information about the cosmological lithium problem. The original hardware as well as the original data analysis software are no longer available. Using the original log books new software has been written that allows for the reading of this data so that it may be fully analyzed. The work on this project involved considerable time studying the raw data in hexadecimal format to look for patterns and structures that could be used to interpret the data. Approximately 800 total lines of code, written in Python, were used to be able to read the data and begin preliminary analysis on it. 1d histograms for individual detectors have been constructed, and the normalization constants for the detector energies have been recovered.

[1] R. A. Alpher, H. Bethe, and G. Gamow, “The origin of chemical elements”, Phys. Rev. 73, 803–804 (1948).

[2] G. J. Mathews, A. Kedia, N. Sasankan, M. Kusakabe, Y. Luo, T. Kajino, D. Yamazaki, T. Makki, and M. E. Eid, “Cosmological solutions to the lithium problem”, in Proceedings of the 15th international symposium on origin of matter and evolution of galaxies (OMEG15) (Mar. 2020).

[3] R. France, L. Baby, C. Bordeanu, T. Delbar, J. Dooley, M. Gai, M. Hass, J. McDonald, A. Ninane, and C. Przybycien, “Destruction of 7li and 7be in astrophysical environments”, Nuclear Physics A718, 398–400 (2003).