Background study of absorbed dose in biological experiments at the Modane Underground Laboratory

Abstract

Abstract. Aiming to explore how biological systems respond to ultra-low background environments, we report here our background studies for biological experiments in the Modane Underground Laboratory. We find that the minimum radioactive background for biology experiments is limited by the potassium content of the biological sample itself, coming from its nutritive medium, which we find in our experimental set-up to be 26 nGy hr -1 . Compared to our reference radiation environment in Clermont-Ferrand, biological experiments can be conducted in the Modane laboratory with a radiation background 8.2 times lower than the reference above-ground level. As the radiation background may be further reduced by using different nutritive media, we also provide measurements of the potassium concentration by gamma spectroscopy of yeast extract (63.3 ± 1.2 mg g -1 ) and tryptone (2.5 ± 0.2 mg g -1 ) in order to guide media selection in future experiments.Afin d'examiner la manière avec laquelle les systèmes biologiques répondent aux environnements caractérisés par un bas niveau de radioactivité, nous avons mesuré le bruit de fond des expériences de biologie menées au Laboratoire Souterrain de Modane. Nous montrons que le bruit de fond est limité par le contenu en potassium au travers des échantillons biologiques euxmêmes, dans leurs milieux nutritifs. Dans le cadre des expériences examinées ici, le bruit de fond de potassium contribue à hauteur de 26 nGy hr -1 . Par rapport à notre environnement de référence à Clermont-Ferrand, des expériences biologiques peuvent être conduites dans le laboratoire souterrain avec une réduction du bruit de fond de 8.2 fois le niveau de la surface. Du fait que le milieu nutritif apporte le plus grand impact au bruit de fond radiatif, nous recommandons la mesure par spectrométrie gamma de la concentration de potassium dans l'extrait de levure (63.3 ± 1.2 mg g -1 ) et le tryptone (2.5 ± 0.2 mg g -1 ) afin de guider la sélection du milieu des futures expériences.

Simulating the Impact of the Natural Radiation Background on Bacterial Systems: Implications for Very Low Radiation Biological Experiments

“…The Ge measurements found a background gamma flux in the center of the great hall of 0.301 γ cm 2 s −1 across all considered flux bins. As our measurements indicated that the gamma spectrum in the LSM is close to that measured in Clermont-Ferrand [40], surface measurements can be obtained by scaling the results found using the underground spectrum by 6.4 (thus ensuring a surface dose of 150 nGy hr −1 , consistent with measured values). At the macroscopic level, the energy binned gamma fluxes were simulated as isotropic, by considering the source to be an r = 3 cm gamma-emitting sphere around a central well in the microplate, which was chosen to be the detector.…”

“…Previously, we discussed the relative contributions of different background sources to biological experiments and presented measured dosages pertinent to these experiments in both above and below ground environments [40]. Briefly, these sources are the terrestrial gamma background, the cosmic charged and neutron background and radiation introduced to the experiment from potassium added to the bacterial growth culture.…”

Fruit Flies Provide New Insights in Low-Radiation Background Biology at the INFN Underground Gran Sasso National Laboratory (LNGS)

“…Several studies performed on unicellular systems, including bacteria, yeast and mammalian cultured cells, have already shown that cell physiology is indeed influenced at different levels by deprivation of normal radiation background. The determination of whether low-radiation background could affect life and development of multicellular and complex organisms remains a highpriority task in most underground laboratory agendas (4,11,36,63). At the LNGS we have successfully started to address this complex question using Drosophila melanogaster as a model system.…”

Understanding low radiation background biology through controlled evolution experiments

“…The Gran Sasso National Laboratory in Italy (depth 1,400 m), the Modane Underground Laboratory in France (depth 1,700 m), the Waste Isolation Pilot Plant in the USA (depth 600 m) and SNOLAB in Canada (depth 2,070 m) are involved in active biology projects. In these environments, the level of the radiation background can be dramatically reduced, to be dominated solely by 40 K present in the biological samples used (Lampe, Marin, et al., ).…”