Speakers
Description
The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose neutrino experiment currently under construction in southern China.
The detector consists of a 35.4 m diameter acrylic sphere filled with 20 000 t of ultra-pure liquid scintillator and makes JUNO the largest liquid scintillator-based, underground neutrino observatory. The primary goal of JUNO is to determine the neutrino mass ordering with a significance greater than 3$\sigma$ after 6 years of data taking and to perform high-precision measurement of neutrino oscillation parameters by measuring the spectrum of the oscillated reactor antineutrino. The detector construction is expected to be completed in 2024.
JUNO has extremely stringent requirements for its background that can overlap with the signals of interest. One of the main background sources is the decay of radioactive nuclides in the materials of the detector and a big effort is necessary to keep the radioactive contamination under control by selecting and purifying the materials used to build the experiment. The most critical component is the liquid scintillator (LS) which is the active material of the detector: the baseline requirements for its radiopurity are less than $10^{-15}$ g/g for $^{238}$U and $^{232}$Th and less than $10^{-16}$ g/g for $^{40}$K.
To achieve the required sensitivities, a new measurement technique has been developed to increase the typical sensitivity of the Neutron Activation Analysis (NAA). We’ve combined the NAA with radiochemical treatments on the sample to concentrate the nuclides of interest and remove the interfering ones, a new delayed coincidence technique for the measurement of $^{238}$U by exploiting the presence of a metastable state in the Uranium activation product, and a dedicated $\beta-\gamma$ coincidence detector to suppress the measurement background. We achieved sensitivities of <0.7 ppq for U, < 8.2 ppq for Th and <1.7 ppq for K and validated the first samples of JUNO LS produced during the commissioning of the purification plants.
| Poster prize | Yes |
|---|---|
| Given name | Andrea |
| Surname | Barresi |
| First affiliation | INFN Milano-Bicocca |
| Institutional email | andrea.barresi@mib.infn.it |
| Gender | Male |
| Collaboration (if any) | JUNO |
