12:00 PM - 12:15 PM
[MTT42-11] Prospects of Ocean Bottom Geoneutrino Detector for direct observation of mantle radioactive element distribution
Keywords:Geoneutrino, Radioactive elements
Geoneutrino is an anti-neutrino emitted in the beta decay of radioactive isotopes in the earth. Geoneutrinos derived from uranium and thorium can be observed with the current observation. It means that the total amount of uranium and thorium in the whole solid earth can be directly estimated by geoneutrino observation. The information from geoneutrino, the amount of uranium and thorium in the earth, is key for understanding the amount of radiogenic heat in the earth that drives geodynamics and understand the origin of the solid earth.
Current geoneutrino observations are being carried out by the neutrino detector "KamLAND" in Kamioka, Gifu Prefecture. Since uranium and thorium are enriched in the crustal rocks, we have to estimate the neutrino flux from the nearby Japanese crust and subtract the crustal neutrino from the observations of KamLAND to obtain mantle geoneutrino. As such, the mantle information obtained from the current observations has a large error due to uncertainties related to crustal geoneutrino.
Ocean Bottom Geoneutrino Detector (OBD) has been proposed as a possible innovation of geoneutrino science. Since the oceanic crust is thinner and contains less uranium and thorium than the continental crust, OBD will allow us to observe mantle-derived geoneutrino with higher accuracy than the current on-land observation. Furthermore, OBD will be movable and will allow us to conduct global multipoint geoneutrino observations. Consequently, ocean bottom neutrino observation will enable us to obtain direct information of the high accuracy three-dimensional distribution of radioactive elements inside the earth. We will introduce the results of geoneutrino observations so far. Also, we will present the future prospects for ocean floor geoneutrino observations.
Current geoneutrino observations are being carried out by the neutrino detector "KamLAND" in Kamioka, Gifu Prefecture. Since uranium and thorium are enriched in the crustal rocks, we have to estimate the neutrino flux from the nearby Japanese crust and subtract the crustal neutrino from the observations of KamLAND to obtain mantle geoneutrino. As such, the mantle information obtained from the current observations has a large error due to uncertainties related to crustal geoneutrino.
Ocean Bottom Geoneutrino Detector (OBD) has been proposed as a possible innovation of geoneutrino science. Since the oceanic crust is thinner and contains less uranium and thorium than the continental crust, OBD will allow us to observe mantle-derived geoneutrino with higher accuracy than the current on-land observation. Furthermore, OBD will be movable and will allow us to conduct global multipoint geoneutrino observations. Consequently, ocean bottom neutrino observation will enable us to obtain direct information of the high accuracy three-dimensional distribution of radioactive elements inside the earth. We will introduce the results of geoneutrino observations so far. Also, we will present the future prospects for ocean floor geoneutrino observations.