New experimental limits on the Pauli-forbidden transitions inC12nuclei obtained with485days Borexino data

Abstract

The Pauli exclusion principle (PEP) has been tested for nucleons (n, p) in 12 C with the Borexino detector.The approach consists of a search for γ, n, p and β ± emitted in a non-Paulian transition of 1P 3/2shell nucleons to the filled 1S 1/2 shell in nuclei. Due to the extremely low background and the large mass (278 t) of the Borexino detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established: τ ( 12 C → 12 C + γ) ≥ 5.0 · 10 31 y, τ ( 12 C → 11 B + p) ≥ 8.9 · 10 29 y, τ ( 12 C → 11 C + n) ≥ 3.4 · 10 30 y, τ ( 12 C → 12 N + e − + νe) ≥ 3.1 · 10 30 y and τ ( 12 C → 12 B + e + + νe) ≥ 2.1 · 10 30 y, all at 90% C.L. The corresponding upper limits on the relative strengths for the searched non-Paulian electromagnetic, strong and weak transitions have been estimated: δ 2 γ ≤ 2.2 · 10 −57 , δ 2 N ≤ 4.1 · 10 −60 and δ 2 β ≤ 2.1 · 10 −35 .

Reconstruction of supernovaνμ,ντ,ν¯μ,

“…Another avenue for drastic improvement is if the threshold can be lowered below the 14 C background. This may be possible through pulse shape discrimination [44]. That allows us to extend our range to lower neutrino energies, increases the overall yield drastically, and may allow reconstructing the SN spectral peak.…”

“…We could not find a direct published reference to the Birks constant for the Borexino scintillator. However, we determine k B = 0.010 cm/MeV using the available quenching data on protons at Borexino [44], i.e., protons of energy 8. quenched to 4.1 MeV and 1.86 MeV, respectively and α particles of 5.4 MeV are quenched by a factor of 13. Note that this is lower than the k B found for electrons in Borexino [45] because low energy electrons are quenched more than protons or ions of the same kinetic energy [46].…”

A Search for Low-energy Neutrinos Correlated with Gravitational Wave Events GW 150914, GW 151226, and GW 170104 with the Borexino Detector

“…The uniquely low background level of the Borexino detector made it possible to set new limits on the effective magnetic moment of the neutrino [21], on the stability of the electron for decay into a neutrino and a photon [31], on the heavy sterile neutrino mixing in 8 B decay [32], on the possible violation of the Pauli exclusion principle [33], on the flux of high energy solar axions [34], on antineutrinos from the Sun and other unknown sources [35], on Gamma-Ray bursts neutrino and antineutrino fluences [36] and on some other rare processes.…”

Borexino calibrations: hardware, methods, and results

“…In this source, 14 C and 222 Rn were simultaneously present in the scintillator. 9 Be n 0-9 sphere R=4 m Energy scale + FV II-IV 394 nm laser light -center PMT equalization IV Figure 9. The 203 Hg γ source that was deployed in June, 2009.…”

“…In Borexino this was accomplished by a ∼10 Bq 241 Am 9 Be neutron source that was inserted into the detector during the second and third internal calibration campaigns. Figure 10.…”