Material capable of sustaining a nuclear chain reaction with slow neutrons in a suitable configuration. Fissility involves capture and fission probabilities, neutron production and losses, rather than positive fission Q value alone. Uranium-235 and plutonium-239 are common examples; fissile is more specific than fissionable by sufficiently energetic neutrons.

Material convertible into a fissile material by neutron capture followed by nuclear transformations. A central example is uranium-238 capturing a neutron and undergoing two beta-minus decays to plutonium-239. Fertile does not mean that thermal-neutron capture immediately causes fission.

A nuclear chain reaction is a sequence in which particles released by one nuclear reaction induce further nuclear reactions. In a neutron-driven nuclear fission chain, emitted neutrons can cause new nuclear fission, be absorbed without causing nuclear fission, or leave the material.

In a simple generation model, let $N_g$ be the mean number of chain-carrying neutrons in generation $g$, and let $k_{\mathrm{eff}}$ be their effective reproduction ratio. Then $N_{g+1}=k_{\mathrm{eff}}{N}_g$. For $k_{\mathrm{eff}}<1$ the mean chain dies away; $k_{\mathrm{eff}}=1$ gives a steady mean population; and $k_{\mathrm{eff}}>1$ gives growth in this fixed-coefficient model. Thus a steady chain has reproduction ratio one, while a growing chain is also self-sustaining in the mean. This elementary generation model does not describe every timescale or spatial change.

Whether material is fissile material depends on reaction probabilities, neutron production and losses in a specified setting. A positive nuclear fission Q value establishes that the final products can release energy, but does not by itself establish the neutron balance.

In 1947, Cesare Lattes, Hugh Muirhead, Giuseppe Occhialini and Cecil Frank Powell reported charged particle tracks in which a stopping particle was followed by a secondary particle. Their paper treated the interpretation as provisional.^[ref] The eventual distinction between pions and muons made a striking use of photography: a tiny permanent record could distinguish particles by how they slowed and transformed.

The method already had a history. In their jointly authored 1937 report, Marietta Blau and Hertha Wambacher described photographic plates exposed for five months at Hafelekar, $2300\mathrm{m}$ above sea level.^[ref] Neither shared the 1950 Nobel Prize in Physics, awarded to Cecil Frank Powell.^[ref] This was a development of photographic particle detection, with earlier contributors, rather than its invention by one person.

In his own later account, Cesare Lattes recalls calibrating emulsion shrinkage and the particle range–energy relation with accelerator-produced particles. Giuseppe Occhialini took borax-treated and untreated plates to Pic du Midi for about a month. The untreated plates provided a control; the treated plates retained more events because latent image fading was reduced. Later, Cesare Lattes exposed plates at the higher Chacaltaya station in Bolivia and obtained more candidate events.^[ref] The Pic du Midi cosmic ray exposure was roughly $3\mathrm{km}$ above sea level.^[ref]

Section of Nomenclature of Carbohydrates (Recommendations 1996) by Alan D. McNaught. The printed document was prepared by Alan D. McNaught; G. P. Moss prepared its web version. No separate section byline or section publication or revision date is established.

Official text: iupac.qmul.ac.uk/2carb/06n07.html

Inspected locators: 2-Carb-6.1, The anomeric centre; 2-Carb-6.2, The anomeric reference atom and the anomeric configurational symbol.

Section of Nomenclature of Carbohydrates (Recommendations 1996) by Alan D. McNaught. The printed document was prepared by Alan D. McNaught; G. P. Moss prepared its web version. No separate section byline or section publication or revision date is established.

Official text: iupac.qmul.ac.uk/2carb/05.html

Inspected locators: 2-Carb-5.4, The Haworth representation; 2-Carb-5.7, Depiction of conformation.

Wilhelm Conrad Röntgen received the award for discovering X-rays.^[ref] The Röntgen X-ray discovery experiment follows how a glowing screen led to tests of a new penetrating electromagnetic radiation.

Hendrik Antoon Lorentz and Pieter Zeeman shared the award equally for research on magnetic influences on electromagnetic radiation.^[ref] The Zeeman discovery experiment of 1896 connects this award to changes in spectral lines.

One half went to Henri Becquerel for discovering spontaneous radioactivity. Pierre Curie and Marie Curie each received one quarter for investigating that radiation.^[ref] Becquerel's uranium-radiation experiment and Curie ionization-current measurement expose two complementary experimental routes into radioactivity.

Lord Rayleigh received the award for gas-mass density investigations and the discovery of argon.^[ref] The Rayleigh-Ramsay argon density experiment shows how a small reproducible density discrepancy can reveal a new chemical element.

Philipp Lenard received the award for research on cathode rays.^[ref] The Lenard cathode-ray window experiment separates the source region from the region where the emerging electrons are studied.

Joseph John Thomson received the award for theoretical and experimental research on electric currents through gases.^[ref] The Thomson charge-to-mass experiment connects cathode rays to the measurable charge-to-mass ratio of an electron.

Albert Abraham Michelson received the award for precise optical instruments and their use in spectroscopy and metrology.^[ref] The Michelson interferometer converts relative wave phase into a readout for precise length measurements.

Gabriel Lippmann received the award for a photographic colour-recording method based on interference.^[ref] The Lippmann colour-recording experiment stores a standing wave pattern in a photographic layer.

Guglielmo Marconi and Karl Ferdinand Braun shared the award equally for developing wireless telegraphy.^[ref] Braun's receiver coupling experiment connects that history to resonance and the selectivity of a receiver.

Johannes Diderik van der Waals received the award for an equation of state describing gases and liquids.^[ref] The Van der Waals equation connects that description to a Van der Waals critical point and Van der Waals liquid-gas coexistence.