-* Acnea nae ne a rian Ot D.6 MATERIAL 1. The standard film packet to be used is Du Pont packet 558 containing one piece of 508 emulsion (range 15 mr to 6 r) and one piece of 1290 (range 5 to 750 r) with a 20-mil-thick lead strip '4 in. wide covering about one-half the length of the packet on both sides. The lead is held on the paper-wrapped packet hy an adhesive. The entire packet with lead strip is enclosed in a heat-sealed envelope of 2-mil polyethylene. The standard badge will be identified by an embossed number. 2. In addition, extra badges and films will be worn by one group. These films will be in Du Pont packet 553 consisting of one piece of 502 (range 30 mr to 15 r), one piece of 510 (range § to 50 r), and one piece of 606 (range 10. to 300 r). The holders for this packet will be of two types: the Los Alamos holder, made of 20-mil sheet brass with two windows on both sides of the holder, one open to the air and one covered with 20 mils of cadmium, and the Bureau of Standards holder, which has no windows but completely encases the film in layers of bakelite, tin, and lead. These films will be identified by X-rayed numbers. 8. Processing chemicals —Ansco Liquadol developer (concentrated liquid), glacial acetic acid, and Ansco Liquafix fixer (concentrated liquid). D.6 PROCEDURE D.6.i Location Film yrocessing and densitometry will be done in the photo trailer aboard the USS Rendova or in the Rsd-Safe Building on Parry Island, When all personnel are evacuated, operations will necessarily be conducted aboard ship. When corditions on Parry island permit, operations may be moved ashore. D.6.2 Film Storage Prior to issue film will be kept in 2 locked refrigerator set between 40 and §7°F. Frost will not be allowed to accumulate, and a desiccant will be used to keep the air dr,. D.6.3 Calibration Film will be calibrated by accurately timed exposureat a fixed distance from a known amount of radium or Co®*. A set of these: standards will be processed, and a calibration curve will be plotted. Included in q set of calibrated film is a control (unexposed) film. The amount of fog on the unexposed film is subtracted from the calibrated film to obtain the net density; gross densities are never used. The formula for exposure time is as follows: t 60xr 2 @x XSOxr 1.8xs where t =time in minutes d = distance in centimeters r= roentgens OEere 8 Re etn oe eeoe s = source strength in milligrams The constant 7.8 is used only if the radium source is enclosed in a platinum capsule of 1-mm wall thickness. For '4-mm platinum wall thickness, this constant is 8.4. For 1-mm monel metal, this conetant is 8.5. For Co®’ of known source strength, the constantis 13.6. Dosimeters are leak tested to detect possible discharge. Leak testing consists in charging the dosimeter to zero, setting it aside for a 24-hr period, and tnen rereading. If the chamber discharge is greater than 10 per cent of full scale, the chamber is declared inoperative.