The Turquoise Book, Operation Ivy (Deleted)

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Object of the Experiment: We have seen, in the discussionof Project3,,3, that several ! surface of the MIKE gadget case indirectly- by utilizingreflect% mirrors. This experimentis designedto supplementand extendsu& Wearly time" documentationby observingthe case disassemblyand A detailedknowledgeof how the gadgetcase disassembledis in. valuableto those interestedin internaltemperatures,pressures, reactionrates, etc. The early formationof "jets"are also of great pression)and may explainthe existenceof temporaryassymetriesin the shock wave. Method aqd Procedure: A. The case will be observeddirectlywith two groupsof 3 4 cameras,the first group operatingat a speed of 13.5millionfrancs per second and the second group operatingat a spesd of 90 thousand frames per second. The first group is designedtindocumentthe case disassembly,and the slower groupwill documentthe initialfireball development. The decreasedtime resolutionof the second groupwill, of course,imply that recordssre takenover a longerperiod of time, Since these camerasachievetheirhigh tilmeresolutionby using the sweepingimage technique(fixedfilm and rotatingmirror), electronictimingdevicesmust be used to close the shuttersafter the fiLm has been swept once. Otherwise,multipleexposurewould result. For lack of a better name, these camerasare called "frame" B. The six camerasused in this experimentwill be housed in a fall-out-proofedshelteron Eogallua- the same shelteras is used

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Ad?ress:Eidgerton, Gerneahausen & Crier, Inc. of Time, With GR-SlitCameras, 2hcting Agency: Edgerton, Germeshausen & Crier, Inc. l Seenote Under “Remmks” of Project 3 .l.

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Object of the Experimentr Thie project is included in the Scientific Photography program b augment the collection of data on illumination a~ a function of tim from exploding atomic weapons. One value of such data is discuesed under Project 3.6. Another value is the establishment of a fund of infon?ation uith which to design and adjust photographic equipment being used under the light conditions generated by atomic bombs. The success of such projects as 6.2 and 6.4a is completely dependent upon good photographic records being obtained - which implies that such things as film sensitivity, shutter speed, and auxiliary lenses (filters) must be selected with great care. Knowledge of the light intensities that will be experienced is essential in making these selecMethod and Procedure: A. Perhaps the simplest and most direct technique for measuring ’ overall illumination as a function of time from an atomic bomb explos-_ ion is afforded by a device known as the GR (General Radio - the + manufacturer) "slit" camera. It consists, essentially, of a rectangular aperture in front of a moving photographic film. The aperture is covered with a strip of neutral density (RD) filter material* - the strip being constructed in such a way as to make available a wide selection of ND filters. That is, as the aperture is traversed, a tion is covered with an ND-1 filter, and so on. The net result is that the photographic record will consist of a series of parallel streaks (dark lines) on the negative. Each streak will have been made by the bomb light; attenuated a known amount by the ND filter in front of that portion of the film. Some of the streaks will be completely overexposed (or underexposed) over a portion of their length. The multiplicity of the filtering available insures us that an adequate readable record can be found somewhere on the film, even if the bomb light deviates strongly from prognostications, A nktral density filter is one which is not color sensitive - that is, it attenuates all visible light by the same amount. An ND-O filter attenuates the light not at all. An ND-1 filter attenuates the light by a factor of 10. In general, an ND-X filter attenuates the light by a factor of lox.

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yb density (opaqueness)Of a streak at a given FIOiIItalong ,_! ct~a is I measureof the light intensityfallingon the fib at ,> rw thatpoiatwas opposite the aperture. By multiplying this .'$&~s the bomb light intensityat that time. By combining the ,..-, tflonaation with the kmwn startingtime and linear velocity HIKE shot, two GR-Slitcameraswill be operal;edon the KING shot, one GR-Slitcamerawill be operatedon the III each case, the cameras will be startedby means of an

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definiterequirementfor 8 device capableof measuringweaponyield during tacticaloperations, Ideally,such a devicewill be: b) Sufficientlyrugged to withstandnormal operatioti use withoutimpairmentof its operationor accuracy, Capableof being operated by its user at a relatiw peat distancefrom the explosion. In aminimum of time. vice. In its presentform it is a steelbox; eighteenincheslong, twelve incheswide, and five inchesdeep - weighingapproximately The theorybehind its operationcan be describedas follows: ' to a maximumwith extremerapidity. It then falls quite rapidlytor minimum and rises again, somewhatless rapitiy,to a secondm&mum, the magnitudeof the secondzw&num being very much less than that ’of the first. After passingthroughthe secondmaximum,it falls off rather gradua3ly(on a millisecondtime scale)to background If'one assumesthat the first minimum is indicativeof a mathematical "similsrity""Condition,it is simplteto 6hoW by means of hydrodynamictheory that the weapon yield is proportionalto the cube of the elapsedtime betweenzero aad the occurrenceof the firstmin3lm7nl.Conversely,to the extentthat the first minirmrm volved tells us that no true scalinglaw other than the above mentioned cube root law is possible. We are thus faced with the followthe ProjectQfficer. For our purposesit will be sufficientto considerthe term as meaning "the same, exceptfor a constant ’

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d _ therefore no true minimumdoes label a state of actual elm& cube root scalinglaw must hold absolutely. I&&IWIIdoes not label a similaritystate at 32:eritselfis 204) of radiochemistry- a few do not. It is not ::j'86 thereis a Strong indication of color sensitivityin the ifindicatedbeforefinal conclusionscan be dravn. On the other kd, it appearsthat a rather good empiricalfit can be made tith ;ct databy using somethingother than the cube root law. At first ' LA. case (b) does not deny the existenceof any nwnber of empiri- ~s:lydeterminedscalingmethods- it says only that no true law h~vusefulit may be. Hence neithercase (a) nor case (lb)have been Ourproblemthen consistsof continuingthe developmentand calibrationof the Bhangmeter,plus attemptingto absolveanomaliesin available.Futureusers of the Ehangmeterwill care little about the typeof scalingused - as long as the resultsare eufficientlyacabovementionedcalibration,and hence continuewhat might be called yieldrange. especiallyin the relativelyhigh Method and procedure: A. me Ehangmeter obtiinsthe above mentionedelapsedtime to firstminimumfor its user in the followingfashion: A llght-sensitiveelectronicvalve observesthe bomb light, the amount of current paseingthroughthe valvebeing proportionalto the intensityof the lightit sees. lhls currentis used to deflectthe sweep in a cathoderay tube 60 that a pictureof the litit intensitycurve is drawn

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on the retentivefluorescentscreenof the tube. A Polaroid"Iand Camera"photographsthis pictureand hence providesa permanentrecm. An electronictimer which interruptsthe cathoderay tube sweepmomentarily everymillisecondis included,so the pictureis made up of a series of dots rather than a continuousline !I!heelapsedtime Is then obtainedby countingthe dots from the start of the curve to ths B. For MIKE shot, one Bhmepleterwill be imkalled on the Parry Islandphoto tower,and anotherwill be installedon the “Estes”. In addition,othersmy be placedat more distit stations. For KING shot, Bhangmeters will be installedon the Pam-y

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Support Required: Part time use of the B-29 assignedticDocu- * Personnelfor this Projectare includedin Task Unit 9 (Documentary

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Object of the Experiment: To obtain a preliminaryphotographicsurveyof the craterCaWed by HIKB shot, for use in the study of earth shock. It is also hoped that a correlationcan be establishedbetweenphotographicevidenceof surfaceperturbationsand the fractionof the bomb's energyrelease that is icoupledwwith the ground. Experienceon shown that early groundsurveysof the craterare Method and Procedumr lishedclose to ElugelabIsland,with adequatemarkingof these points to assure contrastand definitionwhen photographed.These positions must be so selectedas to be easily distinguishableafter the shot as uellasbefore. Preciselocationof groundzero in relationto these positionsis essential,and sufficientaerialphotographyof the shot islandand adjacentislandsprior to the explosionis plannedto confirm the ground control. B. The preliminarysurveywill be conductedfrom aircraftwith verticalcameras as soon as practicableafter the explosionof the MIKE device. The still camerasmountedin the documentaryphotography aircraftwill be used only for obliquecoverageon this project. Effortswill be made to obtainverticaland/orverticalstereoscopic photographswhich will yield informationon the size of the crater and the height of the materialthrownout around the crater lip. Since considerabletime must elapsebefore the cratercan be surveyedin detailby personnelon the site, it is essentialthat the preliminary photographicsurveyyield as much data concerningthe crater as is The experienceof a similar projecton OperationGFLEXNHOUSBindicates that this photographyshouldbe done from an altitudeof not less than 1000 feet. It was also found advantageousto processthe film as soon as possibleafter the mission,in order that new photographs could be obtainedin the event of equipmentmalfunction.

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Object of the Bxperimentr Experimentalair bursta,such as KING shot, imposethe unique 1 problem of determining their actual burst position ia space. Prior ? to the shot, of course, a ground zero is selectedand the detonation mechanismof the bomb is set for a given height of burst. The combin.: ation of bombing inaccuracyand the inherentinaccuraciesof the ’ burst will actuallytake place at the preselectedpo%.ntin space. On the other hand, the successof many experimentalprojectsis dependent: upon knowingthe bomb zero pointwith good accuracy. As a result,a ratherprecisephotographictechniqueis used to locatethe position (in space) of the light flash which characterizesthe explodingbomb, I Hethod and Procedure: ? the detailsof the experimentalmethod are obvious- hence we shall proceeddirectlyto a discussionof the procedure. B. The proposedbomb zero point is 1500 feet above the ground and 5700 feet due north of station250 on Bunit island. The region in space which includesthis point will be observedphotographicalLy by two survey cameras,one locatedon Coral Head and one locatedin the Parry islandphoto tower. IInadditionto seeing the light flash from the explodingbomb, each cansra will see two fixed points- the positionsof which (withrespectto the camera)are known with great accuracy. The distancebetweenthe images of these points on the film suppliesthe film analystwith a simpleand accuratedistancescale, with which to locatethe burst pointwith respectto the fixed points. Measurementof a given film will then locatethe burst point in a plane perpendicularto the axis of the camera - and havingtwo such locationplanes will allow the burst point to be locatedin space. The successof this projectdependsupon accurateinformation as to the camera positions,as well as the positionsof the above essential. Imagesof the fixed calibrationpoints #areobtainedon cated at those points. The films in these camerasare actuallyglass plates,since the experimentalerror would be increasedby the shrinkage of ordinaryfilm. The image of the burstingbomb is obtainedas a small dark spot on the negative(and hence the measurementerrors

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i as It ir ‘,!, _d onlg after losing some portion of their energy in one or more ,:_~:zS* As a result, the existence of a neutron having energy E at , :.s+L3te R from the oomb can indicate at least two possibilities: i,) It rpay have left the bomb with energy E and traversed the (t) It may have left the bomb with some energy greater than E and had its energy reduced by one or more collisions while traversing the distance R. rrch of these possibilities is acsociated with a definite pro- ,L:::tr 0f occurrence. Hence if one measures the total number of such F::z;; to indicate their probable ancestry at the bo&. .A multiplicity 1* rLrhmasurements taken at different distances and for different neu2cr exrgies allou one to build a more complete, as well as consistent, This project is part of a continuing program to determine the 1,):~ distribution of low energy neutrons liberated by various sizes and A. Neutrons of energy in the range from thermal* to .25 electron r::!d (EVVMare essentially all captured by the element cadmium. Ale:, co?~~iumis quite transparent to neutrons of energy greater than .25 T;. ihese facts enable us to deaign a lltargetl’ which, when bombarded *:*A Aeutrons of many energies, is capable of measuring the nu&er of ::~a neutrons in the energy range from .025 to .25 EV. First we select an element which, upon being bombarded with X~~CCS, produces a radioactive by-product. Ideally, the element r?:ccted should be inert with respect to ganma radiationand the by- ;:SCzct should have a sufficiently long half-life to be amenable to :bXatory analysis (counting) techniques. Iwo samples of this element w then prepared - one being coated with cadmium and the other left LI.2Pm.c, These samples are together exposed to the neutron ‘bombardment ~9 subsequently placed in kount,erst’ which measure the induced actl Thermal neutrons are those with energies of the order of ~25 EV.

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The difference in the induced activities of the two samples is then the amount of activity induced in the selected element by neutronsd energy in the range ~125 EV to 0.25 EV. Laboratory calibration of the elemat with neutrons of a known energy (for instance, as can be obtainedwith a Betatron) will then allow this cadmium difference to be interpreted in terms of ntiers of neutrons (in the above mentioned energy range) striking a square centimeter of area of the *"target"elenrent. This, in turn, finally allows one to deduce the total number of those neutrons which are existent (integral over time) at a given diatance (the distance from zero at which the samples were exposed) from the particular bomb detonation. Such a measurement can be regeatedat several distances to obtain an intensity-versus-distancecurve for The method outlined above is used Fn this project, the selected target elements being tantalum and gold. ! B. For MIIE shot, pairs of tantalum and gold samples (one of each being shielded with cadmium at each station) will be plac;d on a line extending along the reef toward Bogallua. TAX first pair will be 100 yards from zero, and a pair will be placed every 100 yards from there to 2500 yards. Tuo sample recovery techniques have been proposed - one being to fasten the samples to a steel cable which can be hauled in after the shot; the other beFng to place the samples on fixed individual pylons and retrieve them after the shot by helicopter. In all probability, a combination of these methods will be used. After recovery, the samples will be shipped to Los Alimos for laboratmy aal~- For KING shot, the same technique will be used. The line of samples will start on the reef (300 feet from proposed around zero) ti extend down the center of Runit~island to the region of-the airstrip proposed groti zero). 1. The samples must be collected as soon as possible after the shot, in order that the radioactive by-products will not decay aw more than is absolutely necessary before laboratory analysis can be done. Also the near (to zero) sample containers are usually in extremely the recovery problems of this project are potentially very severe.

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ich can be I. tze hove outlined technique only allcws deduction of the :* de in other energy ranges, 90 that a much greater percentage .1 . :rzh wasurements for energies greater than 3 million electron :_.+zfor such measurements are not yet proven, so this por-tion of ~~,I~i=eat is prirnarily a feasibility study. In IwrticuJ.ar, it is ,.*i ‘3: the high cross section edxlbited by Indium, for neutrons of

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Ia Alams Scientifia Lab. irrrmel Requirements in the Forward Areat Wunber 1 From ’ To I

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abjectof the Experiment: We have seen in the discussionof ProJect4.1 the importanceof obtainingas much informationas possibleregardingthe distributionl of neutron intensitywith respectto distanceand energy. This project is designedto extendthe measurementstartedin Project4.1, by documentingthe flux of neutronsexhibitingenergiesconsiderably higher than .25 Ev. Method and Procedure: A. The "crosssection"of a substancewith respectto a particu. lar bombardingparticleis a measureof the likelihoodthat the particle will react with the substance. A high cross sectionimplies nitude of this cross sectionIs a functionof the particleenera and type. As …