Implementation and performances of the IPbus protocol for the JUNO Large-PMT readout electronics

The Jiangmen Underground Neutrino Observatory (JUNO) is a large neutrino detector currently under construction in China. Thanks to the tight requirements on its optical and radio-purity properties, it will be able to perform leading measurements detecting terrestrial and astrophysical neutrinos in a wide energy range from tens of keV to hundreds of MeV. A key requirement for the success of the experiment is an unprecedented 3% energy resolution, guaranteed by its large active mass (20 kton) and the use of more than 20,000 20-inch photo-multiplier tubes (PMTs) acquired by high-speed, high-resolution sampling electronics located very close to the PMTs. As the Front-End and Read-Out electronics is expected to continuously run underwater for 30 years, a reliable readout acquisition system capable of handling the timestamped data stream coming from the Large-PMTs and permitting to simultaneously monitor and operate remotely the inaccessible electronics had to be developed. In this contribution, the firmware and hardware implementation of the IPbus based readout protocol will be presented, together with the performances measured on final modules during the mass production of the electronics

Mass testing of the JUNO experiment 20-inch PMTs readout electronics

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose, large size, liquid scintillator experiment under construction in China. JUNO will perform leading measurements detecting neutrinos from different sources (reactor, terrestrial and astrophysical neutrinos) covering a wide energy range (from 200 keV to several GeV). This paper focuses on the design and development of a test protocol for the 20-inch PMT underwater readout electronics, performed in parallel to the mass production line. In a time period of about ten months, a total number of 6950 electronic boards were tested with an acceptance yield of 99.1%

Validation and integration tests of the JUNO 20-inch PMTs readout electronics

The Jiangmen Underground Neutrino Observatory (JUNO) is a large neutrino detector currently under construction in China. JUNO will be able to study the neutrino mass ordering and to perform leading measurements detecting terrestrial and astrophysical neutrinos in a wide energy range, spanning from 200 keV to several GeV. Given the ambitious physics goals of JUNO, the electronic system has to meet specific tight requirements, and a thorough characterization is required. The present paper describes the tests performed on the readout modules to measure their performances.Comment: 20 pages, 13 figure

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Comprehensive measurement of pp-chain solar neutrinos with Borexino

The sun is fueled by fusion reactions that convert hydrogen into helium. The vast majority of the resulting energy is produced through the proton-proton (pp) chain reaction. The byproducts of the various stages of the pp-chain are the so-called pp, pep, 7Be, 8B and hep solar neutrinos. They are a unique tool to gain information about the internal structure of the sun, as well as an intense natural source of neutrinos that can be used to study neutrino properties. Another known set of fusion reactions is the carbon-nitrogen-oxygen (CNO) catalytic cycle which also produces neutrinos, but has not yet been observed.The Borexino detector is a liquid scintillator detector located in Laboratori Nazionali del Gran Sasso in the mountains of central Italy. It is particularly suitable for measuring the solar neutrinos due to its unprecedented radio-purity and resolution at low energies. A comprehensive study of the pp-chain was presented in a recent Nature publication by the Borexino collaboration. The measurement reports pp, 7Be and pep neutrino fluxes with the highest precision ever achieved, 8B with the lowest energy threshold, the first Borexino limit on hep neutrinos, as well as the best limit on CNO neutrinos. These results and their physics interpretations concerning, for example, the so-called solar metallicity puzzle and the electron-neutrino survival probability, as well as other highlights of the analysis, will be summarized in this talk. The talk is presented in the name of the Borexino collaboration

Improved approach of monitoring the effective quantum efficiency of Borexino photomultipliers

Borexino is a liquid scintillator detector located in Laboratori Nazionali del Gran Sasso in the mountains of central Italy. It is equipped with nominally 2212 inward-facing photomultipliers (PMTs) that are used to detect events producing scintillation light.The effective quantum efficiency (EQE) represents the amount of incident light detected by the PMT. It may vary in time due to various factors like light yield change or the PMT aging. Therefore, in order to accurately represent the detector in terms of light collection, we need to account for these changes.We calculate the EQE of each PMT and monitor its changes using the low-energy 14C (Q = 156 keV) events, for which the single-photoelectron mode on each PMT dominates. However, this calculation is sensitive to the position and energy of the selected events as well as to the set of PMTs active in the detector in a given time period. We developed a new more stable method of selecting 14C events and improved the accuracy of the EQE calculation. The highlights of the new approach will be summarized in this talk

Looking inside the sun with the Borexino experiment : detection of solar neutrinos from the proton-proton chain and the CNO cycle

The Sun is fueled by fusion processes occurring in its core that convert hydrogen into helium. Photons produced in these reactions take an order of billion years to reach the surface. However, there is another byproduct of nuclear fusion: neutrinos. They are light and electrically neutral, and, unlike photons, escape the Sun in a matter of seconds. These so-called solar neutrinos are the only carriers of real-time information about the core of our Star. We know that at least 99% of solar energy is generated through the proton-proton (pp) fusion chain. One more process through which hydrogen-to-helium fusion may occur is the catalytic carbon-nitrogen-oxygen (CNO) cycle. As it is hypothesized to be the main source of energy in heavier stars, its discovery would carry implications in astrophysics, and provide insights about the chemical composition of the core of the Sun, which is not yet fully understood. Moreover, we can exploit this intense natural beam of neutrinos radiated by the Sun to study the phenomenon of neutrino oscillation, the discovery of which was achieved thanks to solar neutrino data. The Borexino detector was designed with the primary goal of detecting the so-called 7Be neutrinos, originating from the pp chain. It is particularly suitable for solar neutrino measurement due to its unprecedented radiopurity and resolution at low energies. After ten years of data taking, the Borexino experiment has comprehensively studied all pp-chain neutrinos, not only fulfilling but even surpassing its purpose. This thesis presents the results and implications of this measurement, as well as the analysis behind it. The next milestone of Borexino was to probe the existence of the CNO cycle in the Sun through the detection of neutrinos produced in it. I will describe my work on the methods of monitoring the evolution of the detector and improving the quality of its data, which was deemed crucial for the CNO neutrino analysis. Concluding my thesis, I will present the analysis methods and preliminary results, which show evidence of the existence of CNO neutrinos. The work described in this thesis and my accomplishments are achieved thanks to the collective effort of the Borexino collaboration

Looking inside the Sun with the Borexino experiment: detection of solar neutrinos from the proton-proton chain and the CNO cycle

The Sun is fueled by fusion processes occurring in its core that convert hydrogen into helium. Photons produced in these reactions take an order of billion years to reach the surface. However, there is another byproduct of nuclear fusion: neutrinos. They are light and electrically neutral, and, unlike photons, escape the Sun in a matter of seconds. These so-called solar neutrinos are the only carriers of real-time information about the core of our Star. We know that at least 99% of solar energy is generated through the proton-proton (pp) fusion chain. One more process through which hydrogen-to-helium fusion may occur is the catalytic carbon-nitrogen-oxygen (CNO) cycle. As it is hypothesized to be the main source of energy in heavier stars, its discovery would carry implications in astrophysics, and provide insights about the chemical composition of the core of the Sun, which is not yet fully understood. Moreover, we can exploit this intense natural beam of neutrinos radiated by the Sun to study the phenomenon of neutrino oscillation, the discovery of which was achieved thanks to solar neutrino data. The Borexino detector was designed with the primary goal of detecting the so-called $^7$Be neutrinos, originating from the pp chain. It is particularly suitable for solar neutrino measurement due to its unprecedented radiopurity and resolution at low energies. After ten years of data taking, the Borexino experiment has comprehensively studied all pp-chain neutrinos, not only fulfilling but even surpassing its purpose. This thesis presents the results and implications of this measurement, as well as the analysis behind it. The next milestone of Borexino was to probe the existence of the CNO cycle in the Sun through the detection of neutrinos produced in it. I will describe my work on the methods of monitoring the evolution of the detector and improving the quality of its data, which was deemed crucial for the CNO neutrino analysis. Concluding my thesis, I will present the analysis methods and preliminary results, which show evidence of the existence of CNO neutrinos. The work described in this thesis and my accomplishments are achieved thanks to the collective effort of the Borexino collaboration