Kaul, O N

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ON THE PROCESSING OF NUCLEAR EMULSIONS0 . N. K A U LS a h a  I n s t i t u t e  of  NiMLEAiR P h y s u s  CALrrTT\‘9.{Rvrvivnl March liH,ABSTRACT. 'Phe pjijHu* ^ iv('k nn a ccou n t ot tlie com parativ e  siiu iy  of the various jiroooHSing forinu lao usoii by  tJic au th or durm^^ tlic v o im c  of the em ulsion w ork, iihiiik fioth th ick  and  th in  p la tes . M od ified  tormuUuv fo r  various proeoHsiiijj: stages found to mvt» the host rt^sults h av e  a lso bee ii s ii^ gosti'd .T h e  pa})('i- a lso g iv es  the po iu dration  tim e lU 'oded lor  various de\elo|K‘rs lioth  in the case o f  prosoa k ed  and non-prosoah(M l em ulsions o f  various t hickiu^ssi's. and also an aci’ount nf* the s tu d y  o f  sliriiikagi*. fa c to r  in nuclear t‘mulsi<ms.The author has made a detailed study of the processing lechuitpu  ^ using Ilford Cuy iiiKilear emulsions of 100, 200 and 400 mi(;roii thickness, and also and Gg plates. The details of the investigation are given below uitdor the various heads.Pvt^making stageBefore starting with the (hwelopment, it is necessary to soak the emulsion in water, so that the penetration of the developer may become easier and more rapid. .For this, the temperature and time limits suggested by various workers were used, and the following time and temperature limits were hiund to give the best results :48Emulsion Time Temperatthickness100 0.5 hrs. 2"C200 0.76 hrs. 4“C400 1.25 hm. 6"CTo faculitate penetration, presoaking in distilled water with or without the addtion of the wetting agent is frecpicntly made use ol. This aet-s to swell the gelatine, permitting more rapid diffusion ot the developer. It, however, does not effect the actual development as with the alkaline developments (I)ilworth et alj 1948; Mortier and Vermaesen, 1948; Picciotto, 1949), The suitable temperature at which the penetration is to occur has been found to be 4 C. Below this tern-459460 0 . N . K aulperature the jjeiietratiou time was found to })C too long, and above it, the rate of developer penetration increases less rapidly than its activity.iJevelojmitniTliin emulsions o f 100 //,m order :Two degr(‘(\s of development were* found possible for* thin emulsions. Moderates develoirim^nt was found useful when grain densities of (iomparatively dense tracks (e.g. ju’otojis and a tracks of several M(‘V^ ejiergy) are to Ire measui*(*d. Since in this case it is essential that tlie grains be discrete, moderate development is ]>re- feri'ed. This has a]i additional advantage of great reduction in the fog density. Strong dev(‘lopmcnt, on the otJier hand, although accompanied by an. increased fog background, ])ermits a full utilization of the emulsion sensit ivity  ^and tlie heavy ionizing particles appear as solid columns of silver grains. Series of development tests were condmdrMl to detei*miu(  ^the development time giving the most jrreferred combination of background and track densities. The rr'sults thus obtained are indicated below :Thickness Procedure100 (moderate deveiopnuuit)100 (strong development)Time 10 min,40 inhi. no atiitationThick emulftions of 400 micron order and aboveFor thick emulsions, the two developer solution method as suggested by l l^au and Defilice (194S) is found to give the best results to sc(uire the ev^ en d^evelo])- ment. The first eontains the developing agent without any alkali, permitthig tlui diffusion of the developer into the emulsion without any appreciable amount of actual develojmient occurring. Ihe second bath containing an excess of alkali permits the development to take place.This method re(|uires tliat the veio(uiy of tlu'? travel of a <hange should exceed that of the develo})er itself;- a condition which is not actually satisfied. Also, up to 400 fjim thickness the two bath method eliminates any danger ol‘ i*(‘ti- culation.It has been found by the author that the following modified formulae give the best results in the ease of thick emulsions so fai* as two-bath developmejit is concerned :8ol. A.Elon 1 gmSod. sulphite 20 gmsHydroquinono 3.5 gmsPot. bromide 2.0 gmsDistilled water 2 litresProcessing of Nuclear Emulsions 461Sol. B.Stock Eastman l)jg ... 400 c.c.Distilled water ... IttOOc.c.Sod. carbonate ... 12 gmsFor 200 micron plates the following single solution development formula was found to give the best results. It is the Brussels formula slightly modified bv the author:Sod. sulphite *h) gms.Pot bromide 0.8 gms.Amidol 2.8 gms.Boric acid 12 gms.Water ] lit.PenetratirH j fiine vep ded  f o r  va riou s  d evelopersThe penetration time in minutes of presoaked and non-pi*esoaked emid- sions was investigated l)v tlu^  author at \K C.Jh'Velopvr.'VzolP rison  k<-‘( I Non-pr<tRom*k(‘(lD-IOP i’osou kt'tl N on -p resoak t 'dA m id o lPreH oakod N o ii-2>rosoakod Amitlol ])iRul])liiit«P iv so a k o dXori-] )n»soak('dT<^ m|K>rat art' 4 VSt ag<'PrciRoakingPonotration of tho cold dovclo}XM-W a rm  d ry  d ov e lo j)iu on t24^ 0D r y  c o o l in g  ^S to 2> b a th  a ootio  a c id  (0.r>% )„  ( 1 .0 % )  r,-(-F ix a t io n  (c lea r in g  tinu '+  5 0 %  m ore )W a sh in gISPcHrtration it me in ‘tmn.200/i,/y/, 400g'ia4 .5 l(> 3S<> 10 50S.n S . 5 2 14..-> 10.5 371 .5 5 .0  12:t.o ‘bO 202 . r> 0 .0  122 .5 S.O 20.' The following proc100, 200 and 400 / /  w plates.1 mio in m m .im firn 200/^/a 400/iim5(» 40 10025 35 0(»30 40 10020 30 0225 40 8020 35 70»30*>45 JOO-20 35, 753 hrH. S hi*H. 24 hrs.3 hrK. 8 hrs. 24 hrs.462 0 . N , KautThe following processing formula was found exclusively suitable for thickpJates :Distilled water 8od. sulphite (anhydrous) Pot. bromide (10% solution) AmidolpH of the developerFixing bath (pH 5.3)Distilled water Sod. thiosulphaU^Sod. bisulphiteNH,C1Clearing solution (pH 4.2) Distilled water Ammonium ai;etat(;(Citric acid Thio-urea1000 G.e.12 gins.8 ce3.8 gms. 7.41000 (;c. 400 gms 10 gms7 gms500 ce 15 gms8 gms 8 gmsSmall quantities of sodium bisulphite and ammonium chloride reduce stain­ing and hasten the fixation of the (uuulsion. But large concentrations of these ingredients lead to distortion. Further, in the fixing solution, one half of Hie quantity of hypo was replaced at several intervals, thus avoiding salt concentia- tion shoak. For the same reason, washing was also preceded by a gradual dilution of the fixing solution.ShrinkageThe considerable reduction in the thickness of nuclear emulsions after fixing is due to the high concentration of the silver liromidc in nuclear emulsions. The ratio of the emulsion thickness before and after fixing were found, and the following results were observed :Emulsion thickness in //m.Before processing After processing100 96200 181400 359Processing of Nndear Emulsions 463Increase in the shrinkage factor of Ilford 0^  emulsions :The increase in the shrinkag(‘ factor of the emulsions was iiivestigatol at. 80% relative humidity.363-412tJC^ SO2 62 4T im e o f  storH'^’o in hours at S0%  relative humi<hly F ig . 1. Shrinkage fa e lo r  plotttul agaitisl tlie tm u' of sfojngc* iii liours foi Ilford  (. ^niieleai’ f'liiuIsioiiK.Drying of the emulsionPlates of either thiekneases were soaked iu glycerine solutum aiul dried gently. Rapid drying was avoided, because it ])roduces a skin at the surface which traps the wafer lower down. This in f urn iiroduces stresses at Ihe soft emulsion which produce severe distortions in the tracks. Blowing over the .surfaca- was avoided, because it introduces severe distortioiis, although the temperature was slightly increased to accelerate the process (Dilworth. 1!»51). Edges of the plates usually dry first causing surface rleformations in the emulsion, whicli was also mmnnizeilas far as possible.,A C K  N  () W  L  K  J> K N  T  SThe author is grateful to Prof. B. D. Nagehaudhuri. Director of the Institute, for his encouragement and guidance.Thanks arc also due to Prof. D. N. Kundu, Head of the Accelerator Divismn for providing the laboratory facilities and to Mr. Bhupesh Purkayastha, Head of the Nuclear Chemistry Division, for many helpful discussions.464 0, N. KaulK K K E R J E N C K SBluu, M., and 1)(* fVIirr, J. A., H)4S, Plii/s, Iter., 74, 1J9S.Bilwortti, (\ C., Oechialim, (i. V. S., and Vonnaoson L., 1951, ‘ ‘Fundamental M<M*haniHm of Photographic S(*nHitivity’\ Huttorworih Scientific Publications London, p. 297.Dilworth, (\ (\, Occliialini, (L P. S. and Payne, IL M., 1948, Nature, 164, 102,Mortior, M. and Vcrmaosmi, L., 1948, de PhijHique Nurkaire de NoteNo. r>.Picciotto, E., 1949a, Cauipt, rend, 228, 173.Piccioito, E., 19491), ('nm.pt. rend, 228, 2020.Picciotto, E, 1949c, Compt. rend,, 229, 117.

On the Processing of Nuclear Emulsions

http://arxiv.iacs.res.in:8080/jspui/bitstream/10821/2456/1/On%20the%20processing%20of%20nuclear%20emulsions_O%20N%20Kaul.pdf

On the Processing of Nuclear Emulsions

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