3 items · 2 systems

2026-10-08 Thu

Science & Physics

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  1. 01

    Super-Kamiokande sees reactor electron antineutrinos for the first time, 411.5 live days of SK-Gd data (Δm²₂₁ = 9.08 ± 0.55 ×10⁻⁵ eV²)

    [2026-10-08] · src K. Abe et al. (Super-Kamiokande Collab.), arXiv:2610.03143, submitted to PRL (abstract read, full paper not; not yet refereed)

    • neutrino physics
    • super kamiokande
    • reactor antineutrinos

    Super-Kamiokande, using its gadolinium-loaded phase (SK-Gd, since 2020) to tag neutron captures from inverse beta decay, reports the first observation of reactor electron antineutrinos in 411.52 live days. Spectra and monthly rates match the oscillated reactor prediction after accidental, geoneutrino and spallation backgrounds; the no-reactor hypothesis is disfavoured at about 6σ. Reactor-only oscillation parameters are sin²θ₁₂ = 0.500 ± 0.155 and Δm²₂₁ = (9.08 +0.55/−0.54) ×10⁻⁵ eV². These agree with SK's own solar-neutrino values at 1.9σ (the long-standing solar/reactor Δm²₂₁ tension in the same direction), and a combined solar+reactor fit gives sin²θ₁₂ = 0.332 +0.028/−0.026 and Δm²₂₁ = (8.94 +0.46/−0.47) ×10⁻⁵ eV².

    Why

    It shows that neutron tagging in a large water Cherenkov detector is good enough to do low-energy antineutrino spectroscopy, which is a method that was not practical in pure water. It does not move the field's parameters: sin²θ₁₂ is determined to ±31% here, much worse than dedicated reactor experiments, and the 1.9σ solar/reactor difference is not significant. Its direct bearing on neutrino mass is nil (oscillations fix only splittings); treat the numbers as preliminary until the PRL version and the full paper's systematics are out.

Music Practice

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  1. 01

    Piano: quartal voicings in D-flat https://brona90.github.io/twelve-keys/quartal.html

    [2026-10-08] · src —

    • piano
    • assignment

    Piano today, three days since it was last assigned and the longest gap of the three. The work is quartal https://brona90.github.io/twelve-keys/quartal.html from the twelve-keys library, in D-flat, a key that reads awkwardly and so gets avoided. A longer single block suits piano: about forty-five minutes, all of it on stacked fourths.

    Warmup

    5 minutes: D-flat major scale, two octaves, hands together at quarter = 72, mp, then the same in D-flat dorian. Listen for even touch between the hands, especially across the black-key thumb crossings.

    Technical target

    Play the quartal exercise's voicings in D-flat, left hand alone, then right hand alone, then together. Success criterion: the whole sequence three consecutive times at quarter = 60, 72, then 84 with no hesitation at any voicing change and no looking at the hands on the black-key shapes.

    Musical target

    Take one voicing sequence and play it as a slow, rubato vamp, shaping a single dynamic arc: soft, swell to the middle, release. Let the open fourths ring rather than chopping them, so it sounds like a pad under a melody and not like a drill.

    Stop condition

    Stop at about forty-five minutes, or sooner if the forearms tighten or the voicings start landing wrong more often than right. Piano does not punish a long block, but accuracy past that point is only rehearsing mistakes.

  2. 02

    Listening: Herbie Hancock, "Maiden Voyage"

    [2026-10-08] · src —

    • piano
    • listening

    hearHerbie Hancock — Maiden Voyage · Tidal · Spotify

    Hancock's voicings here are built from stacked fourths, which is the sound today's exercise drills. Listen to how the open chords are left to ring under the melody instead of being played as blocks, and how little the harmony moves over long stretches. That sustained, unhurried quality is today's musical target.