Gamma-ray spectrum of U3O8 sample enriched in 235U (93.2%) measured with HPGe detector

1. Sample Material: U3O8 sealed in a metal can 235U fraction: 93.2330 ± 0.0053 at. % (93.1703 ± 0.0052 wt. %) 234U fraction: 0.9849 ± 0.0029 at. % (0.9800 ± 0.0029 wt. %) 236U fraction: 0.2927 ± 0.0022 at. % (0.2937 ± 0.0022 wt. %) 238U fraction: 5.4895 ± 0.0053 at. % (5.5559 ± 0.0053 wt. %) Material weight: 230.05 ± 0.10 g Aluminum window thickness: 1.9940 ± 0.0052 mm Can inner diameter: 70.00 ± 0.01 mm Material fill height: 15.8 mm Moisture / Volatile content: Insignificant Detectable elemental impurities: 310 μg/g Chemical separation date: 1990 Date of certificate: July 1999 More information can be found via the following links: https://www.energy.gov/sites/default/files/2026-02/CRM%20146%20Uranium%20Gamma%20Spectrometry%20Set%20%2820%25%2C%2053%25%2C%2093%25%29.pdf, https://www.nrc.gov/docs/ML0512/ML051220501.pdf or by contacting the authors. 2. Detector Model: BE2825 (planar broad-energy germanium detector) Cryostat: 7500SL Preamplifier: 2002CSL Cryostat window: aluminum, 0.5 mm Ge crystal: diameter 60 mm, thickness 25 mm Distance from window: 5 mm 3. Measurement details Sample placement: centered on the detector endcap Attenuators: lead (3.17 g/cm2); cadmium (0.88 g/cm2) Measurement period: Dec 2015 – Jan 2016 Total measurement time: 4158843 s Total live time: 4000000 s Dead time: 3.8%. More information can be found in: – F.A. Danevich et al., Search for spontaneous fission of 234U, 235U, 236U, and 238U by gamma spectrometry, Eur. Phys. J. A 61 (2025) 46. DOI: https://doi.org/10.1140/epja/s10050-025-01518-4 – F.A. Danevich et al., Emission intensities of gamma transitions in 235U alpha decay, Eur. Phys. J A 61 (2025) 264. DOI: https://doi.org/10.1140/epja/s10050-025-01746-8 4. Files The spectrum measured with the sample is provided in ‘sample.csv’ Due to the use of a 28-bit multichannel analyzer, the 185.7 keV peak is clipped. The spectrum with the reconstructed statistics of the 185.7 keV peak is provided in ‘sample_reconstructed.csv’. The background spectrum (live time 700000 s, with attenuators placed on the detector) is provided in ‘background.csv’. In every CSV file, the first column is energy in keV (linear energy scale), and the second column is the number of counts.