Birge, Robert W.

Kerth, Leroy T.

Richman, Chaim

Stork, Donald H.

Whetstone, Stanley L.

eScholarship - University of California

Lawrence Berkeley National LaboratoryLawrence Berkeley National LaboratoryTitleTechniques for Handling and Processing Emulsion StacksPermalinkhttps://escholarship.org/uc/item/3bm490f8AuthorsBirge, Robert W.Kerth, Leroy T.Richman, Chaimet al.Publication Date1954-09-08eScholarship.org Powered by the California Digital LibraryUniversity of CaliforniaUCRL-2690Unclassified InstrumentationUNIVERSITY OF CALIFORNIARadiati~n LaboratoryContract Noo W-7405-eng-48TECHNIQUES FOR HANDLINGAND PROCESSING EMUlSION STACKSRobert W0 Bir ge, Leroy T 0 Kerth, Chaim Ri ehman,Donald Ho Stork 9 and Stanley Lo WhetstoneSeptem~r 8, 1954Berkeley, CaliforniaUCRL-2690-2-TECHNIQUES FOR HANDLING AND PROCESSING EMULSION STACKS".Robart 'W. Birge, Leroy T. Kerth, Chaim Ri ohman,DonaldH. Stork, and Stanley Lo 'WhetstoneRadiation Laboratory, Department of Physics,university of California, Berkeley, CaliforniaSeptember S, 1954ABSTRACTThe techniques for assembling, processing and handling largenuclear-emulsion stacks are discussedo Results of experiments.varying the development procedure are presentedoUCRL-2690-3CE>TECHNI'QUES FOR HANDLINGAND PROCESSING EMUISION STACKSRobert Wo Birge~ Leroy To Kerth, Chaim Richman,Donald Ho Storks and Stanley Lo WhetstoneRadiation LaboratorY9 Department of Physics9university of California9 Berkeley~ CaliforniaSeptember 89 1954The Richman group has been developing techniques for processing9handlingand lining up nuclear=e.mulsion stackso Because many differentarticles have appeared on this and rela.ted subjects,9 we are writingmainly a review of the various ~echniques that bave been found mostsatisfactoryo Certain stages of the operationsp however~ are differentfrom those used elsewhere and seem worth commento In general thetechniques are those of the Bristol grouP9l with modifications due to2 ~ 4Brusselsp Bambay~' the Naval Research Laboratory at ~shington, DoCo~Mro Co Waller of Ilford Ltdop and otherso10 PREDEVELOPMENTPROCEDURESThe emulsions as received from Ilford are G-5 pellicles~ 600 micronsthick~ mounted on a so-called temporary glass backing suitable forstripplngo w~ ~radicate the emulsions to clear background tracks becausethe schedule for running time on the Bevatron is uncertaino When themachine is on a standard operating schedule, this step may be omittedoEradicationis done at 33°=36° C for 5<==7 dayso These variationsin time and temperature seem to have little effect on eradicationo Allplatess1oweve~ lose sensitivity~ as shown in Section IVo After the~-4- UCRL=2690emulsions have been allowed to come to equilibrium ~ith about 60% r'elativehumidity in a closed container, they are stripped from the glass by themethod proposed by Mro Walleri vizCl' running a knife around the edge andpeeling the emulsion from the glasso The pellicles have their rough edgestrimmed with scissors, holes punched in each corner, then are stackedtogether (with no separators) between 1/2-inch-thick black bakelite sheets,and clamped tight with screws which pass through the holeso The completedstaok is machined to size in daylight with a milling machinec The edgesexposed to light in this way are blackened less than 200 microns in fromthe edge 0 The machined stack is X=rayed on the edges through slits ateight positions about 1 inch from each corner, leaving a faint line50 P wide penetrati~g about 1/4 inch into each emulsionoAfter the stack has been exposed and is to be developed, the emulsionsare separated, a procedure that is fairly simple if the pellicles weredry before stackingo The Bristol method of wiping the emulsion and treatedglass plates with chamois ~kin in SO C water with 1% glycerine and rollingwith an ordinary wringer has proved quite satisfactory for both large andsmall pellicleso A heavy load on the wringer appears to be necessaryoSeven lbsrper linear inch of emulsion is satisfactoryo The mounted,pellicles are then blotted with filter paper and left overnight tD "set"oIIo DEVELOPMENTPROCEDUREThe developing procedure is essentially that of Bristol,l everything0/ 0done at 5 C except for the 2 1 4-hour dry hot stage at 16 Co (Completegrain Gount versus time~ temperature, and formula is discussed in SectiOLI IVo)-5- UCRL-2690In our work the emulsions are never moved during the processingoThe various solutions flow in and out of the tanks by gravity feed andthe temperature is controlled by cooling coils soldered to the outsideof the tankso A thermocouple connected to a recorder registers thetemperature" Two such tanks, with a total area of 10 square feet, arein operationo After development and stop bath have been finished,the tank is filled with fixer, and a timing system then lets fresh fixerinto the tank for 10 seconds every 3 minuteso The old fixer goes out adrain in the bottom of the tank to an overflowo The flow changes onetank volume each dayo We have also recirculated the fixer through alarge storage tank" Following a suggestion of Dr 0 Gerson Goldhaoor, wenow use a 30% hypo solution (defined as 300 grams of hypo and 2205 gramsof sodium bisulfitein a totalvolumeof 100 cCo of solution) whichclears the emulsions in three dayso With a 40% solutiong clearing takesseven days, and with a 20% solution the time is intermediate between thetwo" * The plates are left in the fixer for one day after clearing, andthen water dilution and washing are startedo The dilution is done slowly,with the same timing system as used for fixing, to keep down the formationof bubbles" The fluid is drawn out of any occasional bubbles with ahypodermic needle as soon as they are observedo ~en the plates arecompletely free of hyp09 a plasticizing solution of 4% glycerine in wateris used and 4% glycerine in alcohol is added at a rate increasing logarith-mically with time until about two volume changes have occurred" (This givesan alcohol concentration of about 87% in two dayso) The solutionis thendrained and the plates finish drying in room air and at room temperature..We ~.Ji.l ~rt.:;.t r 7.,!+""'f.!",,4 -::1:" !"~(:+0 '~Ot " -Y>i~1f. cJp'?!'i~4Q' .i~le. Tnis~:-oced~.lre m.ini:d.zes ~Llh'e1 E'S ani tne la-es Cjd~"-r as ra~ idly as -..rith30% d.irpctly.=6= UCRL=269QIIlo POSTDEVELOPMENTThe emulsions are wiped off with alcohol to remove surface grainsand the excess glass is broken off9 with the aid of a diamond scribe, withreference to the X=ray markso The accuracy of this method allows lineupt'Oabout: 200]1. Following this the plates are dipped in thinned Ducocement (Eo 10 du Pont de Nemours and COo9 Incos>Wilmington 9 Delaware) forprotectiono For more accurate lineup to speed up follow-through work~we glue .brass tabs across the four corners with the aid of a jig and thensand these tabs dawn with reference to the X~ray marks9 using a microscopeunder 210 x magnificaticno ! ~tack of 20 emulsions takes about four hoursto line up to ! 15 )10 This number includes misalignment due to distortionin the emulsion~since alignment 'Was measured ~'byusing diving trecks of340=Mev protonso Mounted uneradicated pellicles developedat 16° C oreradicated pellicles developed at 25° C show distortion amounting to35 CovansoIVo RELATED PROBLEMSAe Variation in Grain Count as a Function of DaveloPment,(1) Of the nearly infinite number of variables that determine thethe final grain count in nuclear emu1sions~ we have varied a few1 andpresent the results heraoThe time and temperature for the "dry stage n were varied for"Bristolfi arid ~Brussels~ developers~ using 600 u Ilford ~5 nuclearemulsions 0 (See Apper~ix fOT composition of developerso) The waterpresoak and cold developer soak were 2 hours and 3 hours respectively at5° G in all caseso For the parti~Jlar dry stage done at 5° Cp some of the-7- UCRL-269Qemulsions were left in the developer during the entire "dry stage" time~ and appear as a separate curve. These data are shown in Figs. 1 through 4.A simple analysis, based on the assumption that the rate of the chemicalreaction is proportional to the number of undeveloped developable grainsmultiplied Py a function of temperature, gives a relation for the contribu-tion to the grain count from the dry stage of the formGD = ~ (l-e- ~(T)t),where GD is the contributionto the gra.in count by the dry stage"an is the number of grainsrendereddevelopableby the passageof a charged particle (function of the velocity only),A-.(T) is a function of the temperature TJt is time in dry stageoThen the total grain count is given byG = GCS CD'whereGas is the contribution to grain count by cold presoak.Such a simple analysis gives a surprising fit to the data. The inclusionof the variation in the concentration of the developer as grains are formed(ioeo~ the "using up" of the developer) would alter the curves in theproper direction to give a better fitvIt is surprising that suoh a large fraction of the grain count is givenby the presoak~ for the supposed function of the presoak is to give thedeveloper a chance to penetrate the emulsion vhile little development takesplace 0-8- UCRL-2690'"40 BRUSSELS DEVELOPER UNERADICATED30t100HItHa:::0LL::t.000 40 80 . 120 160 200.........(/)z~ 40c:>fT=5°CDRYi T= 5°C LEFT IN DEVELOPER! T =16° C DRYi T= 25°C DRYBRUSSELS DEVELOPERERADICATED3020100 40 80 120 160 200TIME IN DRY STAGE(MINUTES)MU-8191Figs. 1 and 2..'"-9-40BRISTOL DEVELOPER UNERADICATED30ft'20T01--1..Ha::0u...'::I..0Q40 800 120 160 200t T = 5° C DRYt T = 5°C LEFT IN DEVELOPER! T= 16°C DRYI T =25°C DRY.........(J)z~ 40<..!)BRISTOL DEVELOPERERADICATED3020IO~=t 1-0 40 20080 120 160TIME IN DRY STAGE (MINUTES)MU-8190Figs. :3 and 4.UCRL-2690-10= UCRL-2690As can be seen from Figs. l~ 2, 3~ and 49 eradication reduces thegrain count to about 50% the uneradiaated value. This is a little greater, loss than other workers have reported.The random grain 1:ackground was examined for emulsions of equalgrain count for the two developers used» and found to be very nearly thesame00We have round that extending the time for 25 C Brussels developmentto 75 minutes increased the random grains to an almost intolerable level.(2) A typicalplot of grain count as a function of depth in 600 JLemulsions shows uniform sensitivity with depth until within 30 ~ to 50 ~of the surfaceo At this depth the grain count starts to falloff, and isonly about half at the very surfaceo We have made little or no investi-gation of the Muse of the surfa~e fall=off.\land have not come to anyconclusion about how to correct it. (With 3')%fixer, :.regr&in count no lon[Ierfalls off at the surface)I. DiscolorationWhen 200 JL emulsions areprocessedby theBristol formula, theysometimes turn a vivid pink. This always happens when they have beeneradicated 0 The cause Is >oxidation of the amidolS1and the effect maybe oured by increasing the Na2S03 in the developer by 30% to 50%, orby using a nitrogen atmosphere during the hot stage, or by leaving a filmof developeron the plates in the hot stage instead ofwiping them off.In addition to showing the pink stain~ the emulsions have almost no ~nsi-tivityo Increasing the amido1 without proportionate increase in Na2S03makes the plates nearly opaqueo The oxidation has never occurred with 600 ~plates 0=11= UC~2690~ Eradication and Soak-uP.,.(1) It was suggested to us by Dora Shermanof this laboratorythat eradicated plates:l when soaked in water 5) take up less water thanuneradicated plateso Tests were ~~ on both 200 ~and 600 uplates toJdetermine whether this effect caused the decreasedin grain count ineradicated plateso Although the eradicated (jmulsi()!.i takes up only1/3 as much water as does an uneradicated emulsion~ changing the soakingtime by a suitable amount to cause either normal or eradicated platesto soak up only I/:3 as muchdevelcper caused no e:hange in th:::1.Trespective grain countso(2) A separate series of tests 'Was run to determine the amount ofwater soaked up by emulsions as a function of temperatureo Aft'3r 6 hours£,the SO C emulsion was transferred to 210 C waterp b~t no further significantincrease in weight occurred (see Figo 5)0 Thus 5) emulsions ~hat are Goaledbefore immersing in the cold presoak absorb less water and devel~per ~hanthose put in at room temperatureo No change in grain co'wt occurs J ho,.Jeyer JIas a result of this change in procedureoDo LocatLTlE:! eventsIn order to relocate events in our emu.lsions, '\.le have had printed(at the suggestion of Mro Erb of Erb and Gray Coo) a rectangular Trlt\'trixof 150 x 150 squares9 each square having a cross in the center and t~o3-digit numbers giving the x and y coordinates of the squareo Thismatrix has been photographically reduced by Mro Phil Carnahan from36 ino x 36 ino to 6 in. x 6 in~ and 3 ino x 3 ino Although we originallyplanned to print only a few of these on glass platesj we have found itICl 100lJJZ<t(!).- 80:r.:~w~ 60IJ...0.-Z 40w(.)0:::Wa..-12- UCRL-269020120t. TRANSFERRED TO 210 WATER00 2 4 6 8 10 12 14 16 18HOURS SOAKED .MU-8189Fig. 5.- "'--13- UCRL-2690possible to mount pellicles, in the usual way, directly onto eitherEastman Kodalith or Ilford Formalith plates that have previously hadthe matrix photographed onto them and been processed. (Ilford willsupply these Formalith plates in any size and of the same thickness astheir treated glass plates.) We believe this method to be as easy andreliable as that recently suggested by Vanderhaege (gluing film to thesurface of finished plates), and furthermore, it does not limit the workingdistance of the objective~ (Qe now 1.J8e 10 rni cJ'on G-5 for oUr grids)Dro Harry Heckman of this laboratory is making prints of thesematrices directly on the pellicles themselves~ and has obtainedsatisfactory resultso However, mistakes in exposure cannot be rectified,and there is the possibility of losing a track along a line of the matrix.ACKNOWLEDGMENTSThe calibration tracks for all this work were from 300- to 340-Mevprotons from the l84-inch cyclotron. Fortunately there has been ampleopportunity to obtain high-energy protons of the riEht intensitY9 owingto the almost continuous operation of the cyclotron for experiments withthe polarized proton beamo The cooperation of Messrso Chamberlain~SegrejJ TriPP9 Wiegand, and Ypsilantis is greatly appreciatedoWe are grateful for the aid of }la-so Beverly Baldridge and l-1rsoMarilynn Harbert in making the grain counts 0Thanks are due also to Dro Jack l-ferritt, lilT. Roy Haddock1 and Hr.Jack SandweissoThe discussions with Dr. Donald Perkins and Dro Peter Fowler fromBristol were of great help in our early work."'"14- UCRL-2690. APPENDIX"Brussels. developer (2,3)Distilled water 1000 ccBoric acid 35 g18 gSodium sulphite (anhydrous)Potassium bromide (10%solution) 8 ccAmidol 4.5 g"Bristo1~ developer (1)Distilled water 930 ccSodium sulphite (anhydrous) 6.7 gSodium bisulphite (saturated solution) 104 CGPotassium bromjde (10% solution) 800 co.Amid01 3.0 gREFmENCES.(1) Ae Do Dainton, A. R. Gattikerjl and Wo 00 Lock~ Phil. Mago ~9396 (1951)(2) Co Co Di1worth~ Go Occhia1ini9 and L. Vermaesen, Bulletindu Centrede PhysiqueNucleairede L9UniversiteLibra de Bruxe11es~ Note ~ 13a~Fe-vrier 1950(3) De 1&1$ Yo Pa1~ Be Peters9 Proco Indian Acad. Sci. ~9 277 (1953)(4) Bo Sti11er~ Mo M. Shapiro9 F. W. OVDel19 Rev. Soi. Instro ~, 340 (1954)

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Techniques for Handling and Processing Emulsion Stacks

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Techniques for Handling and Processing Emulsion Stacks

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