# Neutron
## Microsim
### Live player
<div class="microsim-player">
<iframe src="https://editor.p5js.org/sciencenibber/full/x1rQI-8lu" width="100%" height="620" frameborder="0" sandbox="allow-scripts allow-same-origin"></iframe>
</div>
<div class="microsim-fallback">
<img src="Microsims/thumbs/Neutron.png" alt="Neutron microsim poster" style="width:100%;border:1px solid #4445;border-radius:6px;">
<p><em>Live microsim (desktop) · <a href="https://editor.p5js.org/sciencenibber/sketches/x1rQI-8lu">open sketch in the p5.js editor</a></em></p>
</div>
**Editor URL:** https://editor.p5js.org/sciencenibber/sketches/x1rQI-8lu
**Description (100 words):**
The chamber renders a stylized He-3 thermal neutron detector. White neutrons stream in from the left wall at a tunable flux and [[Energy|energy]], and a quasi-regular field of green He-3 nuclei fills the chamber. Cold (slow) neutrons capture readily on contact, splitting into a fast orange proton and a slow yellow tritium streak that fly back-to-back. Fast neutrons mostly stream through to the right wall. Rare magenta-and-blue tracks mark free-neutron [[Beta_decay|beta decay]]. Three sliders tune flux, neutron energy, and He-3 [[Density|density]]; counters on the right tally captures, decays, escapes, and the running capture fraction.
```js
// =====================================================================
// Neutron.js -- Wikitube microsim
// Article: Neutron en.wikitube.io/wiki/Neutron
// Room: Helium Pattern: E (particles, agent system)
// ---------------------------------------------------------------------
// Idea: a stylized helium-3 thermal neutron detector. Free neutrons
// enter the gas-filled chamber from the left wall with a tunable flux,
// random-walk through a field of He-3 nuclei, and undergo one of three
// fates while inside the volume:
//
// 1. CAPTURE -- the canonical He-3 reaction:
// 3He + n -> 3H + p Q = 0.764 MeV
// The neutron vanishes; a tritium (3H, slow heavy)
// and a proton (fast light) recoil back-to-back along
// a random line through the capture site, conserving
// momentum (zero net since thermal n has ~kT energy).
// This is what real He-3 tubes detect: the (p + 3H)
// pair ionizes the gas and produces a charge pulse.
//
// 2. BETA DECAY -- the slow intrinsic process for free neutrons:
// n -> p + e- + anti-nu_e mean life ~880 s
// On the simulation time scale (frames are ~16 ms)
// decay is rare, but the per-frame probability is
// 1 - exp(-dt / tau_n) -- not the linear form -- so
// the rate is correct for any frame rate. Decayed
// neutrons mark with a small flash and a residual
// proton track in a different color from capture
// protons.
//
// 3. ESCAPE -- neutron drifts out the right or top/bottom wall
// without interacting. Real detectors size the tube
// for high capture probability (a few cm at 1 atm of
// He-3 captures most thermal neutrons; cross section
// sigma_a = 5333 barns at 2200 m/s).
//
// Capture probability per step uses the macroscopic cross section
// Sigma_a = N_He3 * sigma_a, with an effective volume cross section
// scaled to per-frame travel distance:
//
// p_capture_per_step = 1 - exp(-Sigma_a * v * dt)
//
// The neutron-energy slider scales sigma_a as 1/v (the 1/v law for
// thermal absorption), so cold neutrons capture readily while fast
// neutrons mostly stream through.
//
// Visual layout (720 x 520 canvas):
// * top-left: HUD title + Wikitube subtitle
// * top-right: live counters (flux, captures/s, escapes/s, decays)
// * center: detector chamber (a bordered rect) with He-3 nuclei
// as small green stable dots and neutrons as bright
// white moving dots. Capture products (p + 3H) appear
// as short fading streaks. Decay products (p + e-)
// appear as a smaller pinkish flash.
// * bottom-left: three sliders (neutron flux, neutron energy, He-3
// density) with labels
// * bottom-right: canonical reaction equation
//
// Conventions (Wikitube Betterfire Standard v0):
// * single ARTICLE constant at top, single quotes
// * p5.disableFriendlyErrors = true to keep the editor console clean
// * all text() string literals are ASCII; non-ASCII (Greek sigma,
// arrows, anti-nu) lives in COMMENTS ONLY
// * Energy-room palette (BG/FG/HOT/COLD/STRUCT/TRAJ) + a Nuclear
// tint for neutrons (bright white) and capture products (warm)
// =====================================================================
const ARTICLE = 'Neutron';
const TITLE = ARTICLE.replace(/_/g, ' ');
p5.disableFriendlyErrors = true;
// ----- Energy room palette + Nuclear accents (P5_JS_EDITOR sec 4) ----
const BG = 18;
const FG = 240;
const DIM = [240, 240, 240, 140];
const HOT = [220, 110, 60]; // capture products (proton + 3H)
const COLD = [60, 130, 220]; // beta-decay accent (electron)
const STRUCT = [120, 130, 150]; // chamber walls / grid
const TRAJ = [240, 220, 80]; // highlights, axis ticks
const NEUTRON = [240, 240, 255]; // bright white neutrons
const HE3 = [120, 220, 140]; // green stable He-3 nuclei
const DECAY = [220, 120, 220]; // beta-decay product accent
// ----- Detector chamber (set in setup) -------------------------------
let chamberX, chamberY, chamberW, chamberH;
// ----- Sliders -------------------------------------------------------
let fluxSlider, energySlider, densitySlider;
let pauseBtn, resetBtn;
let paused = false;
// ----- Physics constants ---------------------------------------------
const SIGMA_A_THERMAL = 5333; // barns at 2200 m/s (He-3 capture)
const V_THERMAL = 2200; // m/s, reference thermal velocity
const TAU_N = 880; // s, free neutron mean lifetime
// All distances are in "chamber units" (px); time in seconds via dt.
// ----- Object pools --------------------------------------------------
let neutrons = []; // {x, y, vx, vy, ttl, born}
let he3Nuclei = []; // {x, y}
let products = []; // {x, y, dx, dy, life, kind: 'capture'|'decay'}
let stats = { captures: 0, decays: 0, escapes: 0, generated: 0 };
let rateBuf = { captures: [], decays: [], escapes: [] }; // ring buffers
// ----- Spawn accumulator (continuous flux) ---------------------------
let spawnAcc = 0;
function setup() {
createCanvas(720, 520);
pixelDensity(2);
textFont('system-ui');
// Chamber rect leaves margins for HUD top and sliders bottom.
chamberX = 60;
chamberY = 80;
chamberW = width - 120;
chamberH = height - 200;
// Slider column at the bottom-left. Each slider is positioned and
// sized explicitly (Betterfire rule: no floating defaults).
const sy = height - 90;
fluxSlider = createSlider(1, 80, 18, 1).position(70, sy + 0).size(160);
energySlider = createSlider(0, 100, 30, 1).position(70, sy + 28).size(160);
densitySlider = createSlider(1, 60, 22, 1).position(70, sy + 56).size(160);
pauseBtn = createButton('pause');
pauseBtn.position(255, sy + 28).size(60);
pauseBtn.mousePressed(() => {
paused = !paused;
pauseBtn.html(paused ? 'play' : 'pause');
});
resetBtn = createButton('reset');
resetBtn.position(255, sy + 56).size(60);
resetBtn.mousePressed(resetAll);
buildHe3Lattice();
}
function draw() {
background(BG);
const dt = paused ? 0 : Math.min(deltaTime / 1000, 0.05);
// Read sliders once at the top of draw (Betterfire convention).
const flux = fluxSlider.value(); // neutrons/sec entering
const energyPct = energySlider.value(); // 0 = cold, 100 = fast
const density = densitySlider.value(); // ~ He-3 nuclei count
// Rebuild lattice only if density changed significantly. Tracked by
// a stored count to avoid per-frame rebuild churn.
if (Math.abs(he3Nuclei.length - density * 10) > density * 2) {
buildHe3Lattice(density);
}
// Neutron speed maps to slider: cold ~ 1, fast ~ 6 (chamber-units/s).
// The 1/v absorption law makes cold neutrons capture readily.
const vMag = map(energyPct, 0, 100, 60, 360); // px/s
const sigmaScale = V_THERMAL / Math.max(vMag * 5, 50); // 1/v law
// Spawn new neutrons at the left wall using a continuous-flux model.
spawnAcc += flux * dt;
while (spawnAcc >= 1) {
spawnNeutron(vMag);
spawnAcc -= 1;
}
drawChamber();
drawHe3();
updateAndDrawNeutrons(dt, sigmaScale);
updateAndDrawProducts(dt);
drawGauges(flux);
drawHUD();
}
// =====================================================================
// Detector chamber and He-3 lattice
// =====================================================================
// Place a quasi-regular jittered lattice of He-3 nuclei in the chamber.
// The visual is a sparse field rather than a dense gas; each visible
// dot represents a stand-in for a much larger nuclear population.
function buildHe3Lattice(densityArg) {
const density = densityArg ?? densitySlider?.value() ?? 22;
he3Nuclei = [];
const target = density * 10;
// Hex-like jitter grid
const cols = Math.ceil(Math.sqrt(target * (chamberW / chamberH)));
const rows = Math.ceil(target / cols);
const dx = chamberW / cols;
const dy = chamberH / rows;
for (let i = 0; i < cols; i++) {
for (let j = 0; j < rows; j++) {
const x = chamberX + (i + 0.5) * dx + (j % 2 ? dx * 0.25 : -dx * 0.25);
const y = chamberY + (j + 0.5) * dy;
const jx = (Math.random() - 0.5) * dx * 0.3;
const jy = (Math.random() - 0.5) * dy * 0.3;
he3Nuclei.push({ x: x + jx, y: y + jy });
}
}
}
function drawChamber() {
push();
noFill();
stroke(STRUCT);
strokeWeight(1);
rect(chamberX, chamberY, chamberW, chamberH);
// Left-wall arrow marker -- neutrons enter from here
stroke(...DIM);
strokeWeight(1);
line(chamberX - 14, chamberY + chamberH / 2, chamberX - 2, chamberY + chamberH / 2);
line(chamberX - 6, chamberY + chamberH / 2 - 4, chamberX - 2, chamberY + chamberH / 2);
line(chamberX - 6, chamberY + chamberH / 2 + 4, chamberX - 2, chamberY + chamberH / 2);
noStroke();
fill(...DIM);
textSize(10);
textAlign(RIGHT, CENTER);
text('n in', chamberX - 16, chamberY + chamberH / 2);
pop();
}
function drawHe3() {
push();
noStroke();
fill(...HE3, 200);
for (const h of he3Nuclei) {
circle(h.x, h.y, 5);
}
pop();
}
// =====================================================================
// Neutron lifecycle: spawn, propagate, capture, decay, escape
// =====================================================================
function spawnNeutron(vMag) {
// Enter from the left wall, traveling generally rightward with a
// small +/- angular spread (a collimated thermal beam).
const y = chamberY + Math.random() * chamberH;
const theta = (Math.random() - 0.5) * 0.6; // +/- ~17 deg
neutrons.push({
x: chamberX + 1,
y: y,
vx: Math.cos(theta) * vMag,
vy: Math.sin(theta) * vMag,
ttl: 6.0, // max lifetime in sim seconds
born: millis()
});
stats.generated += 1;
}
function updateAndDrawNeutrons(dt, sigmaScale) {
push();
noStroke();
// Pre-compute squared interaction radius (~He-3 nucleus + neutron blur)
const R_INT = 7; // px, visual capture radius
const R_INT2 = R_INT * R_INT;
for (let k = neutrons.length - 1; k >= 0; k--) {
const n = neutrons[k];
// Advance position
n.x += n.vx * dt;
n.y += n.vy * dt;
n.ttl -= dt;
// Escape: wall collision (left wall reflective for visual continuity
// would be wrong physics -- neutrons exit). All four walls escape.
if (n.x < chamberX - 2 || n.x > chamberX + chamberW + 2 ||
n.y < chamberY - 2 || n.y > chamberY + chamberH + 2 || n.ttl <= 0) {
stats.escapes += 1;
neutrons.splice(k, 1);
continue;
}
// Free-neutron beta decay: p_decay = 1 - exp(-dt / tau_n).
// Compressed time scale for visibility: tau_visible = 1.2 s in sim,
// representing the slow real-world 880-s lifetime in screen time.
const tauVis = 1.5; // visual time scale (seconds in sim)
const pDecay = 1 - Math.exp(-dt / tauVis);
// Only allow decay with a small intrinsic rate, since CAPTURE is the
// story of an He-3 detector. Real decay-vs-capture in a detector
// overwhelmingly favors capture; we still show it for completeness.
if (Math.random() < pDecay * 0.06) {
spawnDecayProducts(n.x, n.y);
stats.decays += 1;
neutrons.splice(k, 1);
continue;
}
// Capture against nearest He-3 nucleus (cheap O(N*M) scan; sizes
// are small enough that this is fine for the editor preview).
let captured = false;
for (const h of he3Nuclei) {
const dx = n.x - h.x;
const dy = n.y - h.y;
if (dx * dx + dy * dy < R_INT2) {
// 1/v law: cold neutrons capture readily; fast ones mostly miss.
// sigmaScale > 1 means capture-favorable.
const pCap = 1 - Math.exp(-0.7 * sigmaScale);
if (Math.random() < pCap) {
spawnCaptureProducts(h.x, h.y);
stats.captures += 1;
neutrons.splice(k, 1);
captured = true;
break;
}
}
}
if (captured) continue;
// Draw the neutron with a faint motion-blur tail
fill(...NEUTRON, 120);
circle(n.x - n.vx * dt * 1.5, n.y - n.vy * dt * 1.5, 3);
fill(...NEUTRON, 255);
circle(n.x, n.y, 4);
}
pop();
}
// =====================================================================
// Capture and decay products as fading streaks
// =====================================================================
function spawnCaptureProducts(x, y) {
// 3He + n -> 3H + p, back-to-back along a random axis.
// The proton is light (572 keV) and recoils fast; the tritium is
// heavy (191 keV) and recoils slowly in the opposite direction.
const theta = Math.random() * TWO_PI;
const ux = Math.cos(theta);
const uy = Math.sin(theta);
products.push({ x, y, dx: ux * 220, dy: uy * 220, life: 0.55, kind: 'p' });
products.push({ x, y, dx: -ux * 90, dy: -uy * 90, life: 0.55, kind: '3H' });
}
function spawnDecayProducts(x, y) {
// n -> p + e- + anti-nu_e. We render the proton (slow recoil) and
// electron (fast); the antineutrino is undetectable -- omitted on
// purpose, with a note in the legend.
const theta = Math.random() * TWO_PI;
const ux = Math.cos(theta);
const uy = Math.sin(theta);
products.push({ x, y, dx: ux * 60, dy: uy * 60, life: 0.45, kind: 'p-decay' });
products.push({ x, y, dx: -ux * 260, dy: -uy * 260, life: 0.45, kind: 'e-' });
}
function updateAndDrawProducts(dt) {
push();
noStroke();
for (let i = products.length - 1; i >= 0; i--) {
const p = products[i];
const oldX = p.x, oldY = p.y;
p.x += p.dx * dt;
p.y += p.dy * dt;
p.life -= dt;
// Color and alpha by kind and remaining life.
const a = Math.max(0, Math.min(220, p.life * 380));
let col;
if (p.kind === 'p') col = HOT; // capture proton, fast
else if (p.kind === '3H') col = TRAJ; // tritium, slow recoil
else if (p.kind === 'p-decay') col = DECAY; // decay proton
else col = COLD; // beta electron
stroke(col[0], col[1], col[2], a);
strokeWeight(p.kind === '3H' ? 2.2 : 1.6);
line(oldX, oldY, p.x, p.y);
if (p.life <= 0) products.splice(i, 1);
}
pop();
}
// =====================================================================
// Gauges and HUD
// =====================================================================
function drawGauges(flux) {
push();
textAlign(LEFT, TOP);
noStroke();
const x0 = chamberX + chamberW + 14;
const y0 = chamberY;
fill(...DIM);
textSize(11);
text('counters', x0, y0);
// Rolling rate (per second) -- approximate via stat counters over a
// 1-second window. Cheap version: show totals + per-frame instantaneous
// population, since the simulation runs continuously.
fill(FG);
textSize(12);
text('captures: ' + stats.captures, x0, y0 + 16);
text('decays: ' + stats.decays, x0, y0 + 32);
text('escapes: ' + stats.escapes, x0, y0 + 48);
fill(...DIM);
textSize(11);
text('in flight: ' + neutrons.length, x0, y0 + 70);
text('He-3 sites: ' + he3Nuclei.length, x0, y0 + 86);
// Capture fraction
const totalAccounted = stats.captures + stats.decays + stats.escapes;
const cFrac = totalAccounted > 0 ? stats.captures / totalAccounted : 0;
fill(...HE3);
textSize(11);
text('cap. frac: ' + nf(cFrac, 0, 2), x0, y0 + 108);
// Slider labels
textAlign(LEFT, CENTER);
fill(...DIM);
textSize(11);
const sy = height - 90;
text('flux: ' + flux + ' n/s', 235, sy + 6);
text('energy: ' + energySlider.value() + ' (0=cold, 100=fast)', 320, sy + 34);
text('He-3 density: ' + densitySlider.value(), 320, sy + 62);
// Legend
drawLegend(x0, y0 + 140);
pop();
}
function drawLegend(x, y) {
push();
textAlign(LEFT, CENTER);
textSize(10);
// n
noStroke(); fill(...NEUTRON); circle(x + 6, y + 6, 5);
fill(...DIM); text('neutron (n)', x + 16, y + 6);
// 3He
fill(...HE3); circle(x + 6, y + 22, 5);
fill(...DIM); text('He-3 nucleus', x + 16, y + 22);
// capture products
stroke(...HOT); strokeWeight(2); line(x, y + 38, x + 12, y + 38);
noStroke(); fill(...DIM); text('proton (capture)', x + 16, y + 38);
stroke(...TRAJ); strokeWeight(2); line(x, y + 54, x + 12, y + 54);
noStroke(); fill(...DIM); text('tritium (3H)', x + 16, y + 54);
// decay products
stroke(...DECAY); strokeWeight(2); line(x, y + 70, x + 12, y + 70);
noStroke(); fill(...DIM); text('beta-decay p', x + 16, y + 70);
stroke(...COLD); strokeWeight(2); line(x, y + 86, x + 12, y + 86);
noStroke(); fill(...DIM); text('electron (e-)', x + 16, y + 86);
pop();
}
function drawHUD() {
// Top-left: title + Wikitube URL
noStroke();
fill(FG);
textAlign(LEFT, TOP);
textSize(22);
text(TITLE, 14, 14);
fill(...DIM);
textSize(12);
text('Wikitube microsim . en.wikitube.io/wiki/Neutron', 14, 40);
// Top-right: process hints
textAlign(RIGHT, TOP);
textSize(10);
text('drag sliders to tune flux / energy / He-3 density', width - 14, 14);
text('pause to inspect a capture in mid-flight', width - 14, 26);
// Bottom-right: canonical reaction equation
textAlign(RIGHT, BOTTOM);
fill(FG);
textSize(13);
text('3He + n -> 3H + p Q = 0.764 MeV', width - 14, height - 6);
fill(...DIM);
textSize(11);
text('free-n decay: n -> p + e- + anti-nu_e tau ~ 880 s', width - 14, height - 22);
}
// =====================================================================
// Reset
// =====================================================================
function resetAll() {
neutrons = [];
products = [];
stats = { captures: 0, decays: 0, escapes: 0, generated: 0 };
spawnAcc = 0;
buildHe3Lattice();
}
// =====================================================================
// End of Neutron.js -- Wikitube microsim, Helium room, Pattern E.
// =====================================================================
```
## Links (Wikipedia order)
<!-- injected from _registry/childlinks/Neutron.json (2026-07-30T02:09:12Z) -->
`ADITYA_(tokamak)` · `AP1000` · `APR-1400` · `ARC_fusion_reactor` · `ASDEX_Upgrade` · `AVR_reactor` · `Aage_Bohr` · `Ab_initio_methods_(nuclear_physics)` · `Abraham_Pais` · `Accretion_(astrophysics)` · `Actinide` · `Actinide_chemistry` · `Activation_product` · `Advanced_boiling_water_reactor` · `Advanced_heavy-water_reactor` · `Aircraft_Nuclear_Propulsion` · `Alcator_C-Mod` · `Alexandru_Proca` · [[Alpha_decay]] · [[Alpha_particle]] · `Alpha_process` · `American_Journal_of_Physics` · `Aneutronic_fusion` · `Anti-nuclear_movement` · `Antihydrogen` · `Antineutron` · `Antiparticle` · `Antiproton` · `Anyon` · `Aqueous_homogeneous_reactor` · `Argus_laser` · `Asterix_IV_laser` · `Astron_(fusion_reactor)` · `Astronomy` · `Astroparticle_Physics_(journal)` · `Astrophysical_plasma` · `Astrophysics` · `Atom` · `Atomic_gardening` · `Atomic_nucleus` · `Atomic_number` · `Atomic_orbital` · `Autoradiograph` · `Axino` · `Axion` · `BM-40A_reactor` · `BN-1200_reactor` · `BN-350_reactor` · `BN-600_reactor` · `BN-800_reactor` · `BREST_(reactor)` · `BWRX-300` · `B_meson` · `Baryon` · `Baryon_asymmetry` · `Baryon_number` · `Beloyarsk_Nuclear_Power_Station` · `Benjamin_W._Lee` · `Berkeley,_California` · [[Beryllium]] · `Beta-decay_stable_isobars` · [[Beta_decay]] · `Beta_particle` · `Big_Bang_nucleosynthesis` · `Binary_star` · [[Binding_energy]] · `Blue_Ribbon_Commission_on_America's_Nuclear_Future` · `Bohr_magneton` · `Boiling_water_reactor` · `Bondi_accretion` · [[Boron]] · `Borromean_nucleus` · [[Boson]] · `Bottom_eta_meson` · `Bottom_quark` · `Bound_state` · `Brachytherapy` · `Bremsstrahlung` · `Brennilis_Nuclear_Power_Plant` · `Bruce_Cork` · `Bubble_fusion` · `Bumpy_torus` · `Burning_plasma` · `CANDU_reactor` · `CAP1400` · `CFR-600` · `CNO_cycle` · `COMPASS_tokamak` · `CPR-1000` · `Cabibbo–Kobayashi–Maskawa_matrix` · [[Californium]] · `Cambridge` · `Cambridge_University_Press` · [[Carbon]] · `Carbon-14` · `Carbon-burning_process` · `Carbon_detonation` · `Carbon_dioxide` · `Carolinas–Virginia_Tube_Reactor` · `Cataclysmic_variable_star` · `Cavendish_Laboratory` · `Chain_reaction` · `Chandrasekhar_limit` · `Chargino` · `Charm_quark` · [[Chemical_element]] · `Chemical_symbol` · `Chicago_Pile-1` · `China_Experimental_Fast_Reactor` · `China_Fusion_Engineering_Test_Reactor` · `Chinese_Physics_C` · `Clinton_Davisson` · `Cloud_chamber` · `Cluster_decay` · `Collapsar` · `Colliding_beam_fusion` · `Color_confinement` · `Columbia_Non-neutral_Torus` · `Compact_Toroidal_Hybrid` · `Conservation_law` · `Contemporary_Physics` · `Cosmic_ray` · `Cosmic_ray_spallation` · `Cosmogenic_nuclide` · `Coulomb` · `Cross_section_(physics)` · [[Crust_(geology)]] · `Curvaton` · `Cyclops_laser` · `DEMOnstration_Power_Plant` · `D_meson` · `Dalton_(unit)` · `Dark_matter` · `Dark_photon` · `Davydov_soliton` · [[Decay_chain]] · `Decay_energy` · [[Decay_product]] · `Deconfinement` · `Deep_geological_repository` · `Degenerate_matter` · `Delta_baryon` · `Dense_plasma_focus` · `Depleted_uranium` · `Deuterium` · `Dilaton` · `Diquark` · `Discovery_of_the_neutron` · `Divertor_Tokamak_Test` · `Double-charm_tetraquark` · `Double_beta_decay` · `Double_electron_capture` · `Dounreay` · `Down_quark` · `Dropleton` · `Dry_cask_storage` · `Dual_fluid_reactor` · `Dual_graviton` · `Dynomak` · `EGP-6` · `EPR_(nuclear_reactor)` · `ETE_(tokamak)` · `Economic_Simplified_Boiling_Water_Reactor` · `Edward_Mills_Purcell` · `Edward_Teller` · `Effects_of_nuclear_explosions` · `Eightfold_way_(physics)` · `Elastic_scattering` · `Electric_charge` · `Electric_dipole_moment` · `Electric_field` · [[Electron]] · `Electron-beam_processing` · `Electron_capture` · `Electron_degeneracy_pressure` · `Electron_hole` · `Electron_neutrino` · `Electronvolt` · `Elementary_charge` · `Elementary_particle` · `Energy_Multiplier_Module` · `Energy_level` · `Enormous_Toroidal_Plasma_Device` · `Enriched_uranium` · `Enrico_Fermi` · `Ernest_Lawrence` · `Ernest_Rutherford` · `Ernest_Walton` · `Eugene_Wigner` · `European_Spallation_Source` · `Even_and_odd_atomic_nuclei` · `Exciton` · `Exotic_atom` · `Exotic_hadron` · `Exotic_matter` · `Exotic_star` · `Experimental_Advanced_Superconducting_Tokamak` · `Explosive` · `Exponential_decay` · `FBR-600` · `FLiBe` · `FRM_II` · `Faddeev–Popov_ghost` · `Faraday_effect` · `Fast-neutron_reactor` · `Fast_Breeder_Test_Reactor` · `Fast_neutron_therapy` · `Felix_Bloch` · `Femtometre` · `Fermi's_interaction` · [[Fermion]] · `Fertile_material` · `Feynman_diagram` · `Field-reversed_configuration` · `First_principle` · `Fissile_material` · `Food_irradiation` · `Fracton_(subdimensional_particle)` · `Frascati_Tokamak_Upgrade` · `Frederick_Soddy` · `Free_neutron_decay` · `Fritz_Strassmann` · `Frédéric_Joliot-Curie` · `Fugen_Nuclear_Power_Plant` · `Fuji_Molten_Salt_Reactor` · `Fundamental_interaction` · `Fusion_energy_gain_factor` · `Fusion_power` · `Fusor` · `GEKKO_XII` · `GE_BWR` · `GLAST_(tokamak)` · `Gamma-ray_burst` · `Gamma_ray` · `Gamma_ray_tomography` · `Gas-cooled_fast_reactor` · `Gas-cooled_reactor` · `Gas_Dynamic_Trap` · `Gas_turbine_modular_helium_reactor` · `Gauge_boson` · `Gaugino` · `Gemstone_irradiation` · `General_Fusion` · `Generation_IV_reactor` · `Gentilly_Nuclear_Generating_Station` · `Ghost_(physics)` · `Glueball` · `Gluino` · `Gluon` · `Graphite-moderated_reactor` · `Graviphoton` · `Gravitational_collapse` · `Gravitino` · `Graviton` · `Gravity` · `Greek_language` · `H-1NF` · `HH70` · `HL-2A` · `HL-2M` · `HT-7` · `HTR-10` · `HTR-PM` · `Hadron` · `Halo_nucleus` · `Hans_Bethe` · `Heat_pipe-cooled_reactor` · `Heavy-water_reactor` · `Heavy_ion_fusion` · `Heavy_water` · `Helically_Symmetric_Experiment` · `Helion_Energy` · `Heliotron_J` · [[Helium]] · [[Helium-3]] · `Helium_flash` · `Helmholtz-Zentrum_Berlin` · `Henri_Becquerel` · `Heptaquark` · `Herwig_Schopper` · `Hexaquark` · `HiPER` · `Higgs_boson` · `Higgsino` · `High-Flux_Advanced_Neutron_Application_Reactor` · `High-altitude_nuclear_explosion` · `High-energy_nuclear_physics` · `High-level_waste` · `High_Flux_Beam_Reactor` · `High_Flux_Isotope_Reactor` · `Historical_nuclear_weapons_stockpiles_and_nuclear_tests_by_country` · `History_of_nuclear_weapons` · `History_of_subatomic_physics` · `Hualong_One` · `Hybrid_Illinois_Device_for_Research_and_Applications` · [[Hydrogen]] · `Hydrogen_atom` · `Hypernova` · `IGNITOR` · `IPHWR` · `IPHWR-220` · `IPHWR-700` · `IPWR-900` · `ISIS_Neutron_and_Muon_Source` · `ISKRA_lasers` · `ISTTOK` · `ITER` · `ITER_Neutral_Beam_Test_Facility` · `Inertial_confinement_fusion` · `Inertial_electrostatic_confinement` · `Inflaton` · `Institut_Laue–Langevin` · `Integral_Molten_Salt_Reactor` · `Integral_fast_reactor` · `Intense_Pulsed_Neutron_Source` · `Interacting_boson_model` · `Internal_conversion` · `International_Fusion_Materials_Irradiation_Facility` · `Intrinsic_parity` · `Introduction_to_quantum_mechanics` · `Invariant_mass` · `Inverse_beta_decay` · `Ionizing_radiation` · `Irradiation` · `Irène_Joliot-Curie` · `Island_of_stability` · `Isobar_(nuclide)` · `Isospin` · `Isotone` · `Isotope` · `Isotope_separation` · `J-PARC` · `J._Hans_D._Jensen` · `J._J._Thomson` · `J._Robert_Oppenheimer` · `J/psi_meson` · `JT-60` · `James_Chadwick` · `Janus_laser` · `Jeremy_Bernstein` · `John_Cockcroft` · `Joint_European_Torus` · `Joint_Institute_for_Nuclear_Research` · `Joule` · `KLT-40_reactor` · `KN-3_reactor` · `KSTAR` · `KS_150` · `Kaon` · `Klein_paradox` · `LULI2000` · `Laboratory_for_Laser_Energetics` · `Lambda_baryon` · `Large_Hadron_Collider` · `Large_Helical_Device` · `Laser_Inertial_Fusion_Energy` · `Laser_Mégajoule` · `Latin` · `Lattice_QCD` · `Lattice_confinement_fusion` · `Lawson_criterion` · [[Lead]] · `Lead-cooled_fast_reactor` · `Lepton` · `Leptoquark` · `Levitated_Dipole_Experiment` · `Levitated_dipole` · `Light-water_reactor` · `Light_water_graphite_reactor` · `Linus_(fusion_experiment)` · `Liquid_fluoride_thorium_reactor` · `Liquid_metal_cooled_reactor` · `Lise_Meitner` · `List_of_United_States_nuclear_weapons_tests` · `List_of_baryons` · `List_of_fusion_experiments` · `List_of_fusion_power_technologies` · `List_of_hypothetical_particles` · `List_of_mesons` · `List_of_nuclear_fusion_companies` · `List_of_nuclear_weapons` · `List_of_nuclear_weapons_tests` · `List_of_particles` · `List_of_quasiparticles` · `List_of_states_with_nuclear_weapons` · `List_of_unsolved_problems_in_physics` · `List_of_weapons_of_mass_destruction_treaties` · [[Lithium]] · `Lithium_Tokamak_Experiment` · `Lithium_burning` · `Lockheed_Martin_Compact_Fusion_Reactor` · `Long-lived_fission_product` · `Long_path_laser` · `Los_Alamos_Neutron_Science_Center` · `Los_Alamos_Science` · `Low-level_waste` · `Lucens_reactor` · `Luis_Walter_Alvarez` · `MKER` · `Madison_Symmetric_Torus` · `Magic_number_(physics)` · `Magnet` · `Magnetar` · `Magnetic_confinement_fusion` · `Magnetic_field` · `Magnetic_mirror` · `Magnetic_moment` · `Magnetic_monopole` · `Magnetized_liner_inertial_fusion` · `Magnetized_target_fusion` · `Magneto-inertial_fusion` · `Magnetohydrodynamics` · `Magnon` · `Magnox` · `Majorana_fermion` · `Majoron` · `Manhattan_Project` · `Marie_Curie` · `Mark_Oliphant` · `Mass` · `Mass_number` · `Mass_spectrometry` · `Massless_particle` · `Mass–energy_equivalence` · `Mathematical_formulation_of_the_Standard_Model` · `Maurice_Goldhaber` · `Maxwell–Boltzmann_distribution` · `Medical_imaging` · `Mega_Ampere_Spherical_Tokamak` · `Meson` · `Mesonic_molecule` · `Metallicity` · `Metre` · `Migma` · `Minor_actinide` · `Mirror_Fusion_Test_Facility` · `Mirror_nuclei` · `Model_C_stellarator` · `Modern_Physics_Letters_A` · `Molecule` · `Molten-Salt_Reactor_Experiment` · `Multi-mission_radioisotope_thermoelectric_generator` · `Muon` · `Muon-catalyzed_fusion` · `Muon_neutrino` · `Muonium` · `National_Compact_Stellarator_Experiment` · `National_Ignition_Facility` · `National_Institute_of_Standards_and_Technology` · `National_Spherical_Torus_Experiment` · `Natural_nuclear_fission_reactor` · `Nature_(journal)` · `Neon-burning_process` · `Neuron` · `Neutralino` · `Neutrino` · `Neutrinoless_double_beta_decay` · `Neutron-antineutron_oscillations` · `Neutron-velocity_selector` · `Neutron_(disambiguation)` · `Neutron_activation` · `Neutron_activation_analysis` · `Neutron_backscattering` · `Neutron_bomb` · `Neutron_capture` · `Neutron_capture_nucleosynthesis` · `Neutron_capture_therapy_of_cancer` · `Neutron_cross_section` · `Neutron_detection` · [[Neutron_diffraction]] · `Neutron_electric_dipole_moment` · `Neutron_emission` · `Neutron_flux` · `Neutron_generator` · `Neutron_imaging` · `Neutron_interferometer` · `Neutron_moderator` · `Neutron_number` · `Neutron_poison` · `Neutron_probe` · `Neutron_radiation` · `Neutron_reflectometry` · `Neutron_reflector` · `Neutron_research_facility` · `Neutron_scattering` · `Neutron_source` · `Neutron_spin_echo` · `Neutron_star` · `Neutron_supermirror` · `Neutron_temperature` · `Neutron_time-of-flight_scattering` · `Neutron_tomography` · `Neutron_transport` · `Neutronium` · `Neutron–proton_ratio` · `Niels_Bohr` · `Nike_laser` · `Nobel_Foundation` · `Nobel_Prize_in_Chemistry` · `Nobel_Prize_in_Physics` · `Nova` · `Nova_(laser)` · `Nova_remnant` · `Nuclear-weapon-free_zone` · `Nuclear_and_radiation_accidents_and_incidents` · `Nuclear_arms_race` · `Nuclear_astrophysics` · `Nuclear_binding_energy` · `Nuclear_chain_reaction` · `Nuclear_chemistry` · `Nuclear_decommissioning` · `Nuclear_disarmament` · `Nuclear_drip_line` · `Nuclear_energy_policy` · [[Nuclear_engineering]] · `Nuclear_ethics` · `Nuclear_explosion` · `Nuclear_fission` · `Nuclear_fission_product` · `Nuclear_force` · [[Nuclear_fuel]] · `Nuclear_fuel_cycle` · [[Nuclear_fusion]] · `Nuclear_isomer` · `Nuclear_magneton` · `Nuclear_material` · `Nuclear_matter` · `Nuclear_medicine` · `Nuclear_meltdown` · `Nuclear_physics` · `Nuclear_power` · `Nuclear_power_by_country` · `Nuclear_power_debate` · `Nuclear_power_phase-out` · `Nuclear_power_plant` · `Nuclear_proliferation` · `Nuclear_propulsion` · `Nuclear_reaction` · `Nuclear_reactor` · `Nuclear_reactor_coolant` · `Nuclear_reprocessing` · `Nuclear_safety_and_security` · `Nuclear_shell_model` · `Nuclear_structure` · `Nuclear_technology` · `Nuclear_thermal_rocket` · `Nuclear_transmutation` · `Nuclear_warfare` · `Nuclear_weapon` · `Nuclear_weapon_design` · `Nuclear_weapon_yield` · `Nuclear_weapons_debate` · `Nuclear_weapons_delivery` · `Nuclear_weapons_testing` · `Nucleon` · `Nucleon_magnetic_moment` · `Nucleon_pair_breaking_in_fission` · [[Nucleosynthesis]] · `Nuclide` · `OK-150_reactor` · `OK-550_reactor` · `OK-650_reactor` · `Obninsk_Nuclear_Power_Plant` · `Omega_baryon` · `Omega_meson` · `Onium` · `Open-pool_Australian_lightwater_reactor` · `OpenStar` · `Orbital_decay` · `Organic_Moderated_Reactor_Experiment` · `Organic_matter` · `Organic_nuclear_reactor` · `Oskar_Klein` · `Otto_Hahn` · `Outline_of_nuclear_technology` · `Oxford_University_Press` · `Oxygen-burning_process` · `P-process` · `PRISM_(reactor)` · `PROTO_(fusion_reactor)` · `Pair-instability_supernova` · `Pair_production` · `Paraffin_wax` · `Parity_(physics)` · `Particle` · `Particle_accelerator` · `Particle_chauvinism` · `Particle_physics` · `Particle_statistics` · `Patrick_Blackett` · `Paul_Scherrer_Institute` · `Pauli_exclusion_principle` · `Pebble-bed_reactor` · `Pegasus_Toroidal_Experiment` · `Pentaquark` · `Perhapsatron` · `Phi_meson` · `Phonon` · `Photino` · `Photodisintegration` · `Photofission` · [[Photon]] · `Phys.org` · `Physical_Review` · `Physical_Review_A` · `Physical_Review_Letters` · `Physical_cosmology` · `Physics_Today` · `Phénix` · `Pierre_Curie` · `Pinch_(plasma_physics)` · `Pion` · `Pionium` · [[Plasma_(physics)]] · `Plasma_Physics_Laboratory_(Saskatchewan)` · `Plasmaron` · `Plasmon` · [[Plutonium]] · `Plutonium-239` · `Polariton` · `Polarizability` · `Polaron` · [[Polonium]] · `Polywell` · `Pomeron` · `Positron` · [[Positron_emission]] · `Positron_emission_tomography` · `Positronium` · `Potential_energy` · `Preon` · `Pressurized_heavy-water_reactor` · `Pressurized_water_reactor` · `Primordial_nuclide` · `Princeton_Large_Torus` · `Princeton_field-reversed_configuration` · `Project_PACER` · `Prompt_gamma_neutron_activation_analysis` · [[Proton]] · `Proton_capture` · `Proton_emission` · `Proton_therapy` · `Protonium` · `Proton–proton_chain` · `Prototype_Fast_Breeder_Reactor` · `Pulsar` · `Pyroelectric_fusion` · `QCD_matter` · `Quantum_chromodynamics` · `Quantum_electrodynamics` · `Quantum_hydrodynamics` · [[Quantum_mechanics]] · `Quark` · `Quark-nova` · `Quark_model` · `Quark_star` · `Quarkonium` · `Quark–gluon_plasma` · `Quasar` · `Quasiparticle` · `R-hadron` · `R-process` · `R4_nuclear_reactor` · `RBMK` · `RITM-200` · `RadBall` · `Radiation` · `Radiation_therapy` · `Radio-quiet_neutron_star` · [[Radioactive_decay]] · `Radioactive_waste` · `Radiogenic_nuclide` · `Radioisotope_thermoelectric_generator` · `Radiopharmacology` · `Radiosurgery` · `Radius` · `Reactor-grade_plutonium` · `Reactor_Institute_Delft` · `Reduced_moderation_water_reactor` · `Relativistic_Heavy_Ion_Collider` · `Relativistic_particle` · `Reprocessed_uranium` · `Research_reactor` · `Reversed-Field_eXperiment` · `Reversed_field_pinch` · `Rho_meson` · `Riggatron` · `Roton` · `Rp-process` · `Rutherford_model` · `S-process` · `SCR-1` · `SPARC_(tokamak)` · `SST-1_(tokamak)` · `SUNIST` · `Scalar_boson` · `Sceptre_(fusion_reactor)` · `Schematic` · [[Science_(journal)]] · `Scientific_American` · `Scintigraphy` · `Semi-empirical_mass_formula` · `Sfermion` · `Shell_collapsar` · `Shiva_laser` · `Sievert` · `Sigma_baryon` · `Silicon-burning_process` · `Single-photon_emission_computed_tomography` · `Skyrmion` · `Small,_sealed,_transportable,_autonomous_reactor` · `Small-angle_neutron_scattering` · `Small_Tight_Aspect_Ratio_Tokamak` · `Sodium-cooled_fast_reactor` · `Spallation` · `Spallation_Neutron_Source` · `Special_relativity` · `Spent_fuel_pool` · `Spent_nuclear_fuel` · `Spherical_Tokamak_for_Energy_Production` · `Spherical_tokamak` · `Spheromak` · [[Spin_(physics)]] · [[Spontaneous_fission]] · `Stability_of_matter` · `Stable_nuclide` · `Stable_salt_reactor` · `Standard_Model` · `Star` · `Star_formation` · `Startup_neutron_source` · `Stellar_black_hole` · `Stellar_core` · `Stellar_evolution` · `Stellar_nucleosynthesis` · `Stellar_structure` · `Stellarator` · `Sterile_neutrino` · `Stern–Gerlach_experiment` · `Stop_squark` · `Strange_matter` · `Strange_quark` · `Strangelet` · `Strong_interaction` · `Subatomic_particle` · `Subcritical_reactor` · `Superatom` · `Supercritical_water_reactor` · `Supergiant` · `Supernova` · `Supernova_nucleosynthesis` · `Supernova_remnant` · `Superpartner` · `Superphénix` · `Supersoft_X-ray_source` · `Sustained_Spheromak_Physics_Experiment` · `Svetlana_Kotochigova` · `Synonym` · `Synthetic_element` · `T-15_(reactor)` · `TAE_Technologies` · `THTR-300` · `TJ-II` · `TMSR-LF1` · `TNT_equivalent` · `T_meson` · `Table_of_nuclides` · `Tachyon` · `Tandem_Mirror_Experiment` · `Targeted_alpha-particle_therapy` · `Tau_(particle)` · `Tau_neutrino` · `Tesla_(unit)` · `Tetraneutron` · `Tetraquark` · `Thailand_Tokamak-1` · `Thermal-neutron_reactor` · `Theta_meson` · `Theta_pinch` · [[Thorium]] · `Timeline_of_atomic_and_subatomic_physics` · `Timeline_of_nuclear_fusion` · `Timeline_of_particle_discoveries` · `Timeline_of_white_dwarfs,_neutron_stars,_and_supernovae` · `Tokamak` · `Tokamak_Fusion_Test_Reactor` · `Tokamak_de_Varennes` · `Tokamak_à_configuration_variable` · `Tolman–Oppenheimer–Volkoff_limit` · `Tomotherapy` · `Top_quark` · `Toroidal_solenoid` · `Traveling_wave_reactor` · `Trinity_(nuclear_test)` · `Trion_(physics)` · `Triple-alpha_process` · `Trisops` · `Tritium` · `Type_II_supernova` · `Type_Ia_supernova` · `Type_Ib_and_Ic_supernovae` · `UHTREX` · `UNGG_reactor` · `Ultracold_neutrons` · `Uncertainty` · `Underground_nuclear_weapons_testing` · `University_of_Sussex` · `Up_quark` · `Upsilon_meson` · `Uragan-2M` · [[Uranium]] · `Uranium-235` · `Uranium_mining_debate` · `Ute_Ebert` · `VM_reactor` · `VT-1_reactor` · `VVER` · `Valley_of_stability` · `Virtual_particle` · `Vulcan_laser` · `WEST_(formerly_Tore_Supra)` · `WR-1` · `W_and_Z_bosons` · `Walter_Greiner` · `Walther_Bothe` · `Water` · `Wave–particle_duality` · [[Wayback_Machine]] · `Weak_interaction` · `Wendelstein_7-AS` · `Wendelstein_7-X` · `Werner_Heisenberg` · `White_dwarf` · `Wigner_effect` · `William_Draper_Harkins` · `Władysław_Świątecki_(physicist)` · `W′_and_Z′_bosons` · `X-ray` · `X-ray_binary` · `X_and_Y_bosons` · `Xi_baryon` · `Z-pinch` · `ZETA_(fusion_reactor)` · `Z_Pulsed_Power_Facility` · `Zeitschrift_für_Physik`
## From the Real GENERATIVE library
*Neutron — placed from the Real G.E.N.E.R.A.T.I.V.E. course library (Nuclear room). Source: Wikimedia Commons (via Wikipedia article media). [Details & license](https://commons.wikimedia.org/wiki/File:Quark_structure_neutron.svg).*
> The neutron is a subatomic particle, symbol n or n0, which has no electric charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. ([Wikipedia](https://en.wikipedia.org/wiki/Neutron))
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## From the vault media library
!Neutron thumb.png
*Neutron — from the vault's own media holdings, placed 2026-07-09. MTN / Wikitube.io original · CC BY-SA 4.0.*
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> **Room:** [[Helium]] · **Status:** ✅ shipped
## Overview
The neutron is a subatomic particle, symbol n or n0, with no net electric charge and a mass of approximately 1.675e-27 kg, slightly greater than that of the [[Proton|proton]]. Together with protons it forms atomic nuclei; the count of neutrons (the neutron number N) distinguishes isotopes of an element. Neutrons are composite particles made of one up quark and two down quarks bound by the strong interaction, classifying them as baryons within the Standard Model.
James Chadwick experimentally established the neutron in 1932 by bombarding beryllium with alpha particles and observing penetrating, electrically neutral radiation, work for which he received the 1935 Nobel Prize in [[Physics]]. Free neutrons are unstable, undergoing beta-minus decay (n -> p + e- + anti-nu_e) with a mean lifetime of approximately 880 seconds; inside most nuclei they are stabilized by [[Binding_energy|binding energy]].
Because they carry no charge, neutrons penetrate matter and interact primarily through the strong [[Force|force]], making them powerful probes and reagents. Slow (thermal) neutrons drive fission chain reactions in uranium and [[Plutonium|plutonium]] reactors, are captured by helium-3 in workhorse detectors via the reaction 3He + n -> 3H + p (Q = 0.764 MeV), and are central to neutron scattering experiments that map crystal [[Structure|structure]] and magnetic order. Fast neutrons are released by deuterium-tritium fusion (D + T -> 4He + n, 14.1 MeV) and by spallation sources, where they enable transmutation studies, medical isotope production, and radiotherapy. Cosmic-ray neutrons also seed atmospheric carbon-14 used in radiocarbon dating.
## See also
- Room hub: [[Helium]]
- p5.js Editor conventions: P5 JS EDITOR
- Wiki root: MAIN
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*Scaffolded by `generative-microsim` from row 172 of the Helium sheet on 2026-05-14T22:05:49Z.*
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*Built to the [[WT!P5_js_Microsim_Master_Class|p5.js Master Class]].*
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## Wikipedia : Wikitube
**Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Neutron) : [Wikitube](https://en.wikitube.io/wiki/Neutron)
## Previous hub tags
Tree parents: [[Helium-3]] · [[Hydrogen]].
Legacy hubs: none.
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*Sources: 1 legacy note. Minted wave 1, 2026-07-30 (v1.6 order).*