Follow-up Q04: the phosphorescent-sulphide screens (Radiant Energy, p.54)

Date: 2026-10-06. Follow-up investigator (STEP F). Web time: about 3 minutes (Chrome; timer 1791343919 to 1791344107, 188 s). Stopped early: the source of both passages was found, and the phosphor questions are answered by standard references.

The question

In Radiant Energy (1926, p.54) Moray describes the spinthariscope and adds: "One may, by using certain varieties of phosphorescent sulphide, succeed in making screens showing the phenomenon of dissociation, now [not] only with salts of radium, but also with other substances. Herein be the door to greater discoveries." What might he have been detecting, or hoping to detect, with such screens? Which sulphides and activators respond to radiations other than alpha particles, and which are worth trying today? Is the passage Moray's own or Le Bon's, and what did Le Bon mean? [In Isotopes in Ionic Recovery of U3O8 Moray notes that calcium sulphide exposed to the sun for a few seconds "radiates invisible light for eighteen months".]

What Moray's texts say

• Radiant Energy, printed p.54 (PDF p.55): "On striking phosphorescent bodies the alpha particles render them luminous. It is this property which is the basis for the operation of the spinthariscope, an instrument which renders visible the permanent dissociation of matter. It consist[s] of a screen of suphide of zinc, above which is placed a small metal rod, the end of which has been dipped in a solution of chloride of radium. ... This emission is visible because each particle is made apparent through the enormous degree of lateral perturbation produced by its shock on the sensitive surface, in the same way that raindrops falling into the water produce ripples which exceed their diameter. One may, by using certain varieties of phosphorescent sulphide, succeed in making screens showing the phenomenon of dissociation, now only with salts of radium, but also with other substances. Herein be the door to greater discoveries." [read: _text/Books-Works-by-Moray-Radiant-Energy-radiant-energy-1926-a4beae.txt, lines 2817-2834]
• The 4th ed. (1960), the 5th ed. (1978) and the "Pepe/Tesla Pages" copy of The Sea of Energy read "not only" and "Herein is the door" [read: _text/Books-Works-by-Moray-Sea-of-Energy-*-4thed-4e182f.txt line 3314ff; -5thed-0d3c5c.txt line 14322ff; -TheSeaofEnergy-fddc18.txt line 6411]. So "now only" is a typing slip in the "1926" printing, as the question suggested.
• Printed p.55 continues (also Le Bon's text): beta rays "immediately render luminous by impact bodies capable of phosphorescence, even when separated from them by aluminum foil. The phosphorescence is very bright in platinocyanide of barium and some kinds of diamonds". It ends a paragraph with a sentence that is not in Le Bon's paragraph: "Herein may lie a prototype of the action of the universe." [read: same file, lines 2866-2894]
• Isotopes in Ionic Recovery of U3O8 (copyright 1958, revised 1959), p.5-6: "In respect to induced radio-activity, certain forms of matter or particles can be stored on bodies for a great length of time and expend themselves very slowly. In experiments on phosphorescence it was noted that sulphide of calcium exposed to the sun for a few seconds, radiates invisible light for eighteen months, as is proved by the possibility of photographing the isolated object in the dark room or in the most complete darkness. At the end of eighteen months it no longer gives any radiation, but still preserves a residual particle charge which persists for an indefinite period, and can be made visible by causing infra-red rays to fall on the surface of the isolated body." The cover lists the Institute's work as including "the study of rays beyond the light rays". [read: _text/Books-Works-by-Moray-Istopes-in-Ionic-Recovery-of-U308-004a4b.txt, pp.1, 5-6]
• Related, in the folder: "Bro. Noffsinger's Description of System" (handwritten, 8 Jan 1984) lists the detector stone as "germanium alloy, bismuth, iron sulfide, molybdenite, triboluminescent zinc and radium chloride" [read: facts.json entry zz-Misc/noffsinger_01-08-1984.pdf, digest only; provenance not established]. No other passage in the folder's Moray texts names a zinc or calcium sulphide screen, an activator or an experiment with one (grep of _text for zinc sulph-, phosphoresc-, triboluminesc-).

What was searched

What was found

1. Both passages are Gustave Le Bon's, made impersonal; the closing sentence is Moray's

• Le Bon, The Evolution of Matter (1905; Legge transl.), Book IV ch.III: "If this emission is visible, as Crookes says, because 'each particle is made apparent solely through the enormous degree of lateral perturbation produced by its shock on the sensitive surface, in the same way that raindrops falling into the water produce ripples which exceed their diameter'. I have succeeded, by using certain varieties of phosphorescent sulfide, in making screens allowing the phenomenon of dissociation to be observed, not only with salts of radium, but also with divers substances, notably thorium and uranium (1)." [web https://www.rexresearch.com/lebonmat/lebonmat.htm]
• Le Bon's footnote (1): "The phosphorescent sulfide is spread in a layer, so thin as to be transparent, on a strip of glass first covered with varnish. The side coated with phosphorescent matter is then placed on the substance it is desired to examine, and the other face of the glass is observed through a magnifying glass. All uranium and thorium minerals, and even an ordinary incandescent mantle, give out a luminescent scintillation indicating a dissociation of matter; but in order to see this, it is necessary that the eye be rendered sensitive by previously remaining in the dark for a quarter of an hour." [web, same page]
• Moray's changes: Le Bon's "I have succeeded" becomes "One may ... succeed"; "divers substances, notably thorium and uranium" becomes "other substances"; the footnote (the method and the named samples) is dropped; "Herein be [is] the door to greater discoveries" is added. The added sentence is not in Le Bon's paragraph, so it is Moray's (or his editor's) own. The raindrop image is Crookes's, quoted by Le Bon; Moray drops the credit to Crookes too.
• The calcium sulphide sentence: Le Bon, same book: "I must remark with respect to induced radioactivity that certain forms of energy can be stored in bodies for a great length of time and expend themselves very slowly. In my former experiments on phosphorescence I noted that calcium sulfide, exposed to the sun for a few seconds, radiates invisible light for 18 months, as is proved by the possibility of photographing the insolated object in the dark room or in the most complete darkness. At the end of 18 months it no longer gives any radiation, but still preserves a residual charge which persists for an indefinite period, and can be made visible by causing invisible infrared rays to fall on the surface of the insolated body." [web, same page]. Moray's 1958-59 text changes "In my former experiments" to "In experiments ... it was noted", "forms of energy" to "forms of matter or particles", "residual charge" to "residual particle charge", "insolated" (sun-exposed) to "isolated", and drops "invisible" before infra-red. The change from energy to particles fits Moray's particle language elsewhere in that booklet; whether it was deliberate is not known.
• No credit to Le Bon was seen in either passage.

2. What Le Bon meant

• "Dissociation of matter" is Le Bon's thesis that all matter slowly breaks up and radiates; radioactivity is the conspicuous case of a universal property (see Q01). His screens were offered as a direct way to see that dissociation in substances other than radium. The samples he names, uranium and thorium minerals and a thoriated gas mantle, are genuinely radioactive alpha emitters (thorium oxide and its decay chain in mantles) [memory: high], so a thin zinc sulphide screen would scintillate on them as he says. His observation is consistent with ordinary alpha radioactivity; it does not by itself show dissociation of non-radioactive matter. Le Bon's wider claim (all bodies dissociate) is what the screens were meant to support.
• Le Bon's phosphor work belongs with his 1896 "black light" (invisible radiation, which he said phosphorescent bodies emit and which fogs plates in darkness). Wikipedia: "its existence was never confirmed and, similar to N rays, it is now generally understood to be non-existent", although it "attracted much attention among French scientists", many supported him, and he was nominated for the 1903 Nobel Prize in Physics [web https://en.wikipedia.org/wiki/Gustave_Le_Bon]. The Nature index of the period lists a critical item, "Le Bon's Black Light merely a False Light" [web snippet, Dolnoslaska Biblioteka Cyfrowa PDF of Nature, found via Google; not opened]. M. J. Nye's study "Gustave Le Bon's black light: a study in physics and philosophy in France at the turn of the century" (1974) is the standard history [web citation via Google; not read].
• The 18-month calcium sulphide observation, read in today's terms: a doped calcium sulphide that stores charge in deep traps after light exposure, with stored energy released as visible light when infrared light falls on it, is a real and well-known effect (photostimulable or "electron-trapping" phosphors). Smet et al. (2010): "Upon adding Sm3+ to CaS:Eu, a photo stimulable phosphor (rather than a persistent phosphor) is obtained as the trap levels introduced by Sm3+ are too deep to be thermally emptied. However, upon illumination of the material with infrared excitation, visible emission can be obtained" [web https://pmc.ncbi.nlm.nih.gov/articles/PMC5445864/]. Le Bon's "residual charge ... made visible by ... infrared rays" matches this. His claim of "invisible light" photographed for 18 months is part of the black-light claims and was not confirmed by others in the sources seen; a weak long afterglow of an impure calcium sulphide is a possible ordinary reading [memory: medium].
• Le Bon himself pointed to activators: "Pure bodies such as calcium sulfide, strontium sulfide, etc., are never phosphorescent. They only become so on being mixed with very small quantities" of other bodies; "It suffices ... for traces of foreign bodies to be added to certain sulfides --- those of calcium, barium, strontium, etc. --- for them to acquire the marvelous property of becoming phosphorescent". He drew an analogy: radium chloride is to inactive barium chloride as impure, phosphorescent barium sulphide is to pure barium sulphide [web, Evolution of Matter, same page]. He also wrote that infrared can be studied with "a reagent --- zinc sulfide with green [copper] phosphorescence --- as sensitive as silver gelatino-bromide is for visible light" (the "[copper]" bracket is in the Rex transcription), and in The Evolution of Forces: zinc sulphide previously exposed to daylight "becomes immediately extinguished" under lamp light (infrared), while "The sulfides of calcium and strontium being little sensitive to the infrared rays, light up very well ... with the light of a lamp or even of a candle", and "If zinc sulfide is a valuable reagent for the infrared rays, calcium sulfide is as valuable for ... the blue and violet rays" [web http://www.rexresearch.com/lebonfor/evforp2.htm]. Infrared quenching of copper-activated zinc sulphide is a real effect [memory: high].

3. Which sulphides and activators respond to what

Standard facts, with tags: - Zinc sulphide with silver (ZnS:Ag): blue, about 450 nm; the alpha scintillator of the spinthariscope tradition (Crookes 1903) and of today's alpha probes [web https://en.wikipedia.org/wiki/Zinc_sulfide ; https://en.wikipedia.org/wiki/Scintillator]. As a thin powder layer it is very efficient for alpha particles and has "very low sensitivity for beta particles and gamma" rays (Eljen product text) [web snippet https://eljentechnology.com]; a 2021 fibre detector "could selectively detect alpha particles and it was insensitive to beta particles and gamma" rays [web snippet https://pubmed.ncbi.nlm.nih.gov, Yamamoto 2021]. Radon progeny in air give alpha background counts on such detectors [web snippet, US7375336B2]. - ZnS:Ag mixed with lithium-6 fluoride (or boron-10): thermal-neutron screens. The neutron is captured by Li-6 (or B-10), which emits an alpha and a triton that light the ZnS; gamma sensitivity is about 10^-6 [web snippets: EJ-426 https://eljentechnology.com ; Scintacor neutron screens https://scintacor.com ; Pritchard et al. 2020 https://pmc.ncbi.nlm.nih.gov/articles/PMC8207483 ; ResearchGate study of ZnS(Ag)/6LiF]. ZnO:Zn/6LiF is a low-afterglow alternative [web snippet, Sykora 2018, ScienceDirect]. - ZnS with copper (ZnS:Cu): green, long afterglow (glow-in-the-dark), also electroluminescent panels [web Wikipedia Zinc_sulfide]; its stored glow is quenched by infrared (Le Bon's "reagent for the infrared") [memory: high; Le Bon web above]. Radium luminous paint was radium mixed with copper-activated zinc sulphide [memory: high]. - ZnS with manganese (ZnS:Mn): orange-red, about 590 nm [web Wikipedia]; strongly triboluminescent (glows when crushed or rubbed) [memory: high]. This is the most likely meaning of "triboluminescent zinc" in Noffsinger's 1984 list of the detector stone [inference]. - Calcium sulphide with bismuth (CaS:Bi): "Balmain's paint", marketed in 1870, "the first well-recognized commercial luminescent pigment" [web Smet 2010]. Calcium and strontium sulphides with europium plus samarium (CaS:Eu,Sm; SrS:Eu,Sm; SrS:Ce,Sm): photostimulable, read out by infrared; studied as X-ray storage imaging and optically stimulated luminescence dosimeters [web Smet 2010; snippets Ravotti 2007 HAL hal-00327469; Miyajima 1995 INIS; Wiley OSL references]. - Other screens in the same texts: barium platinocyanide (Roentgen's X-ray screen) glows under beta and X/gamma rays (Moray p.55, from Le Bon) [read]. Modern X-ray screens use calcium tungstate or terbium-doped gadolinium oxysulphide [memory: high]. Cadmium sulphide, a sulphide named in Moray's 1968 proposal for its "internal amplification", is a photoconductor rather than a screen phosphor [read: Q02 notes; memory: high]. Zinc and cadmium sulphides are wide-gap II-VI semiconductors, so a phosphor screen and a photoconductive cell are close relatives [memory: high].

Reasoning: what Moray might have been detecting, or hoping to detect

The record gives no experiment by Moray with such a screen. Competing readings: - A. Copying, with an editorial flourish. The paragraph is Le Bon's first-person report of his own screens; Moray made it impersonal, cut the named samples, and added "Herein be the door to greater discoveries", as he added "Herein may lie a prototype of the action of the universe" on the next page. On this reading the sentence shows what Moray read and found inspiring, not what he built. - B. Le Bon's universal dissociation, adopted. Moray kept Le Bon's claim that screens can show "dissociation" in "other substances" and dropped the restriction to uranium and thorium. That fits Q01's reading B (ordinary matter emits below instrument thresholds) and his "sea of energy". What he would have hoped to see: scintillations from ordinary, non-radioactive matter. What a screen would actually show there, in mainstream terms: background from radon progeny, trace uranium, thorium and potassium-40, and cosmic rays [memory: high]; this would need a blank comparison to read. - C. Phosphors in his own hardware and products. Radium plus zinc compounds appear in the reported composition of his detector stone (Noffsinger 1984, "triboluminescent zinc and radium chloride"); radium-zinc sulphide is the chemistry of luminous paint; and his Cosray applicators were radium-type sources (arbiter.md). A sulphide screen is also the simplest way to check whether such a stone or applicator emits alpha particles. This reading links the screen to things Moray did make, but no text of his connects them. - D. "Rays beyond the light rays". The Isotopes booklet copies Le Bon's calcium sulphide storage-and-infrared passage, and its cover and Moray's 1945 title Beyond the Light Rays speak of rays beyond visible light. Le Bon recommended copper zinc sulphide as an infrared reagent and calcium sulphide for blue-violet. Moray may have seen phosphors as detectors of invisible radiation generally (Le Bon's black light), not of alpha particles only. These are not exclusive. Reading A is fully documented (the copying); B and D are what the copied passages say; C is an inference from other documents.

Worth trying today (for the reader; no verdicts)

• A commercial ZnS:Ag alpha screen (or Eljen-type ZnS-coated sheet) laid on a thoriated mantle, a uranium mineral, and a non-radioactive control, viewed with a dark-adapted eye and a loupe, or a phone camera on long exposure, or a photomultiplier/silicon photomultiplier in a dark box. This repeats Le Bon's footnote experiment with a control he did not report.
• ZnS:Ag/6LiF neutron screen (EJ-426 type) for neutrons; a plastic scintillator for beta and cosmic-ray muons [memory: high].
• ZnS:Cu glow powder charged by light, then exposed to a warm infrared source: Le Bon's infrared quenching.
• CaS:Eu,Sm or SrS:Eu,Sm (sold as infrared-laser viewing cards) charged by light, stored for days or weeks, then read with infrared: the modern form of Le Bon's 18-month observation [memory: medium for the commercial cards].
• ZnS:Mn crushed or rubbed in the dark: triboluminescence, relevant to the "triboluminescent zinc" of the detector stone.

Still open

Whether Moray ever built or used such screens (no lab note in the folder); whether he knew or acknowledged the passages were Le Bon's; the date he first used them (1945 printing is the earliest dated); Le Bon's own report of the screens in French (L'Evolution de la matiere, 1905) and whether he named the sulphide variety (the English text does not); Nye 1974 on how Le Bon's phosphorescence claims were received.

New leads (for sites.md)

• (follow-up Q04) The spinthariscope "phosphorescent sulphide" sentence (Radiant Energy p.54) and the calcium sulphide "eighteen months" passage (Isotopes in Ionic Recovery of U3O8, 1958-59, p.6) are Le Bon's, made impersonal; "Herein be the door to greater discoveries" is Moray's addition. Le Bon's footnote: thin sulphide screen on varnished glass; uranium and thorium minerals and an incandescent mantle scintillate. Bears on Claim 5 and on how far Moray's physics pages are his own.
• (follow-up Q04) Phosphor chemistry and the detector stone: Noffsinger's "triboluminescent zinc and radium chloride" fits ZnS:Mn and radium luminous-paint chemistry; a ZnS:Ag screen is the obvious test for alpha emission from surviving tubes (Perreault reported no radioactivity, method not given). Bears on Claim 4.