More Like this

1. Forbidden transitions in nuclear weak processes relevant to neutrino detection, nucleosynthesis and evolution of stars

   https://doi.org/10.1051/epjconf/201922301063  

   Suzuki, Toshio ; Chiba, Satoshi ; Yoshida, Takashi ; Takahashi, Koh ; Umeda, Hideyuki ; Nomoto, Ken’ichi ; de Angelis, G. ; Corradi, L. ( January 2019 , EPJ Web of Conferences)

   The distribution of the spin-dipole strengths in 16 O and neutrino-induced reactions on 16 O areinvestigated by shell-model calculations with new shell-model Hamiltonians. Chargedcurrent and neutral-current reactioncross sections are valuated in various particle and γ emission channels as well as the total ones at neutrinoenergies up to Eν≈ 100 MeV. Effects of multiparticle emission channels, especially the αp emission channels, on nucleosynthesis of 11 B and 11 C in core-collapse supernova explosions are investigated. The MSW neutrino oscillation effects oncharged-current reaction cross sections are investigated for future supernova burst. Electron capture rates for a forbidden transition 20 Ne(O g.s. + ) → 20 F(2 g.s. + ) in stellar environments are evaluated by the multipole expansion method with the use of shell model Hamiltonians, and compared with those obtained by a prescription that treats the transition as an allowed GamowTeller (GT) transition. Different electron energy dependence of the transition strengths between the two methods is found to lead to sizable differences in the weak rates of the two methods. 

   more » « less
2. JUNO sensitivity to low energy atmospheric neutrino spectra

   https://doi.org/10.1140/epjc/s10052-021-09565-z  

   Abusleme, Angel ; Adam, Thomas ; Ahmad, Shakeel ; Ahmed, Rizwan ; Aiello, Sebastiano ; Akram, Muhammad ; An, Fengpeng ; An, Guangpeng ; An, Qi ; Andronico, Giuseppe ; et al ( October 2021 , The European Physical Journal C)

   Abstract Atmospheric neutrinos are one of the most relevant natural neutrino sources that can be exploited to infer properties about cosmic rays and neutrino oscillations. The Jiangmen Underground Neutrino Observatory (JUNO) experiment, a 20 kton liquid scintillator detector with excellent energy resolution is currently under construction in China. JUNO will be able to detect several atmospheric neutrinos per day given the large volume. A study on the JUNO detection and reconstruction capabilities of atmospheric $$\nu _e$$ ν e  and $$\nu _\mu $$ ν μ  fluxes is presented in this paper. In this study, a sample of atmospheric neutrino Monte Carlo events has been generated, starting from theoretical models, and then processed by the detector simulation. The excellent timing resolution of the 3” PMT light detection system of JUNO detector and the much higher light yield for scintillation over Cherenkov allow to measure the time structure of the scintillation light with very high precision. Since $$\nu _e$$ ν e  and $$\nu _\mu $$ ν μ  interactions produce a slightly different light pattern, the different time evolution of light allows to discriminate the flavor of primary neutrinos. A probabilistic unfolding method has been used, in order to infer the primary neutrino energy spectrum from the detector experimental observables. The simulated spectrum has been reconstructed between 100 MeV and 10 GeV, showing a great potential of the detector in the atmospheric low energy region. 

   more » « less
3. Evaluation of gadolinium’s action on water Cherenkov detector systems with EGADS

   https://doi.org/10.1016/j.nima.2020.163549  

   Marti, LI ; et, al ( January 2020 , Nuclear instruments methods n physics research)

   Used for both proton decay searches and neutrino physics, large water Cherenkov (WC) detectors have been very successful tools in particle physics. They are notable for their large masses and charged particle detection capabilities. While current WC detectors reconstruct charged particle tracks over a wide energy range, they cannot efficiently detect neutrons. Gadolinium (Gd) has the largest thermal neutron capture cross section of all stable nuclei and produces an 8 MeV gamma cascade that can be detected with high efficiency. Because of the many new physics opportunities that neutron tagging with a Gd salt dissolved in water would open up, a large-scale R&D; program called EGADS was established to demonstrate this technique’s feasibility. EGADS features all the components of a WC detector, chiefly a 200-ton stainless steel water tank furnished with 240 photo-detectors, DAQ, and a water system that removes all impurities from water while keeping Gd in solution. In this paper we discuss the milestones towards demonstrating the feasibility of this novel technique, and the features of EGADS in detail. 

   more » « less
4. Limits on Astrophysical Antineutrinos with the KamLAND Experiment

   https://doi.org/10.3847/1538-4357/ac32c1  

   Abe, S. ; Asami, S. ; Gando, A. ; Gando, Y. ; Gima, T. ; Goto, A. ; Hachiya, T. ; Hata, K. ; Hayashida, S. ; Hosokawa, K. ; et al ( January 2022 , The Astrophysical Journal)

   We report on a search for electron antineutrinos (${\overline{\nu }}_e$) from astrophysical sources in the neutrino energy range 8.3–30.8 MeV with the KamLAND detector. In an exposure of 6.72 kton-year of the liquid scintillator, we observe 18 candidate events via the inverse beta decay reaction. Although there is a large background uncertainty from neutral current atmospheric neutrino interactions, we find no significant excess over background model predictions. Assuming several supernova relic neutrino spectra, we give upper flux limits of 60–110 cm⁻²s⁻¹(90% confidence level, CL) in the analysis range and present a model-independent flux. We also set limits on the annihilation rates for light dark matter pairs to neutrino pairs. These data improve on the upper probability limit of⁸B solar neutrinos converting into${\overline{\nu }}_e$,$P_{{\nu }_e\to {\overline{\nu }}_e}<3.5\times {10}^{-5}$(90% CL) assuming an undistorted${\overline{\nu }}_e$shape. This corresponds to a solar${\overline{\nu }}_e$flux of 60 cm⁻²s⁻¹(90% CL) in the analysis energy range.

    

   more » « less
5. Retrieval of energy spectra for all flavours of neutrinos from core-collapse supernova with multiple detectors

   https://doi.org/10.1093/mnras/staa3287  

   Nagakura, Hiroki ( November 2020 , Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT We present a new method by which to retrieve energy spectrum for all falvours of neutrinos from core-collapse supernova (CCSN). In the retrieval process, we do not assume any analytic formulas to express the energy spectrum of neutrinos but rather take a direct way of spectrum reconstruction from the observed data; the singular value decomposition algorithm with a newly developed adaptive energy-gridding technique is adopted. We employ three independent reaction channels having different flavour sensitivity to neutrinos. Two reaction channels, inverse beta decay on proton and elastic scattering on electrons, from a water Cherenkov detector such as Super-Kamiokande (SK) and Hyper-Kamiokande (HK), and a charged current reaction channel with Argon from the Deep Underground Neutrino Experiment (DUNE) are adopted. Given neutrino oscillation models, we iteratively search the neutrino energy spectra at the CCSN source until they provide the consistent event counts in the three reaction channels. We test the capability of our method by demonstrating the spectrum retrieval to a theoretical neutrino data computed by our recent three-dimensional CCSN simulation. Although the energy spectrum with either electron-type or electron-type antineutrinos at the CCSN source has relatively large error compared to that of other species, the joint analysis with HK + DUNE or SK + DUNE will provide precise energy spectrum of all flavours of neutrinos at the source. Finally, we discuss perspectives for improvements of our method by using neutrino data of other detectors. 

   more » « less