Intensification of XRay Diffraction Films to Increase SpeedG. M. Corney and H. R. Splettstosser Citation: Review of Scientific Instruments 23, 98 (1952); doi: 10.1063/1.1746194 View online: http://dx.doi.org/10.1063/1.1746194 View Table of Contents: http://scitation.aip.org/content/aip/journal/rsi/23/2?ver=pdfcov Published by the AIP Publishing Articles you may be interested in Xray diffraction from oriented films AIP Conf. Proc. 226, 476 (1991); 10.1063/1.40567 Use of Polaroid Film in XRay Diffraction Rev. Sci. Instrum. 34, 930 (1963); 10.1063/1.1718628 High Speed in XRay Diffraction Work by Use of Polaroid Film Rev. Sci. Instrum. 34, 708 (1963); 10.1063/1.1718556 A Proposed Method for Electronic Intensification of SingleCrystal XRay Diffraction Images Rev. Sci. Instrum. 25, 1032 (1954); 10.1063/1.1770914 The Use of Film in XRay Diffraction Studies Rev. Sci. Instrum. 22, 809 (1951); 10.1063/1.1745768

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98 LABORATORY AND SHOP NOTES

purely rotational motion, but at no sacrifice in generality, since purely translatory motion has no effect upon the accelerometer. The only one of Euler's equations which is of interest is that one which describes the moment produced about the X axis by the motion of the accelerometer in space, since moments about the other axes are absorbed by the rotor supports in such a way that no instrument output is produced. The resultant moment M., which causes rotation of the seismic mass about the X axis, is given by

M.= IxOl.+w.wz(Iz- I.), (1)

where Ix, I., I.=seismic mass moments of inertia about the respective principal axes; 01. = component of angular acceleration about pivot axis; w., w.= components of angular velocity about the y and z axes, respectively. Equation (1) shows that M. con­tains the expected term proportional to acceleration about the sensitive axis 01. but also contains an error term which depends upon the geometry of the seismic mass and the angular velocities about the two insensitive axes. Since it is not generally possible in aircraft to make angular acceleration measurements about one axis in the absence of angular motion about other axes, it is ap­parent that the seismic mass should be designed so that Iz=Iy. The simplest such design is that of a cylinder or disk, whereas the bar of many commercial angular accelerometers is about as far from this optimum design as is possible.

Equation (1) has been written for an idealized instrument, as illustrated in Fig. 1, in which the output axis is coincident with one of the principal axes (the X axis) of the seismic mass. In some instruments this is not quite the case because of the presence of balance adjustment screws, spring attachment projections, holes, etc., which are not symmetrically located. For the more general case, then, the expression for M. would have to be suitably modified to include product of inertia terms. However, almost always such corrections are negligible.

The order of magnitude of the angular velocity error in bar­rotor instruments may be more readily appreciated if Eq. (1) is replaced by the approximation

(2)

which is based on the fact that for most bar rotors Ix and Iz are nearly equal, while ly is comparatively small (Le., Ix> lOly). It is apparent from Eq. (2) that the error may easily amount to an appreciable percentage of the desired output in common airplane maneuvers. Thus, an instrument with a bar rotor should be used only when high accuracy is not required, or when wyand wz are known to be small enough to limit the error to less than the per­missible maximum. In some cases, when wyand wz are known, cor­rections may be made using Eq. (1). However, for the greatest accuracy and usefulness, the angular accelerometer rotor should be cylindrical, or should be especially designed in accordance with the rule that Iy must equal Iz.

It should also be noted, that any technique for measuring angular acceleration involving the use of two linear accelerometers mounted a distance apart in the airplane is subject to precisely the same error as that obtained with a bar-type angular accelerom­eter. This error becomes readily apparent if complete dynamical equations of the same nature as Eq. (1) are written for the linear accelerometers.

Intensification of X-Ray Diffraction Films to Increase Speed

G. M. CORNEY AND H. R. SPLETTSTOSSER

Kodak Research Laboratories. Eastman Kodak Compa1lY. Rochester 4. New York

(Received March 19. 1951)

A CONSIDERABLE saving in exposure time in the photo­graphic recording of x-ray diffraction patterns can be

achieved by the chemical aftertreatment, known as intensification, of the normally processed photographic film in Kodak Intensifier

A B c FIG. 1. Power diffraction patterns of lithium fluoride. made with copper

K radiation on Kodak Industrial X-Ray Film. Type K. A. with normal exposure, conventional processing; B. with t normal exposure, intensified in 10-6; Ct with i normal exposure, conventional processing.

In-6.' This procedure has proved successful in recent years in the treatment of underexposed photographic negatives. Speed in­creases of up to 4 times can be obtained on high speed x-ray films at the cost of about one-half hour additional processing time. In Fig. 1, A is a normally exposed, normally processed Debye-Scherrer-Hull pattern of lithium fluoride made with copper K radiation on Kodak Industrial X-Ray Film, Type K; B is the same pattern exposed for one-fourth the time and intensified in in In-6 after normal processing; and C is the same exposure as B but not intensified. The intensified image (B) has greater grain­iness than the normally processed film and a yellow color. The speed gain, however, is so great that these drawbacks become acceptable in many cases.

Figure 2, in which the original photographic density (Do) is plotted against the density of the intensified film (DI), shows the great increases in density and film speed obtained. (Note that the (Do) scale is greatly expanded, compared with that for DI.) Since the slope at any point of the curves of Fig. 2 is the ratio of the gradients of the characteristic curves, it is apparent that a great increase in film contrast for a given exposure is obtained. The densities were read on a photoelectric densitometer using a type 929 photocell and unfiltered tungsten illumination.

The intensification procedure is simple~ It can be carried out in full room illumination and can be stopped whenever the results suit the operator. Films which are to be intensified should be handled as little as possible and then only by the extreme corners or edges. Films may be intensified either immediately following

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LABORATORY AND SHOP NOTES 99

normal fixation or after normal washing and drying. Both dry films and those directly from the fixer are washed 5 to 10 minutes in running water, hardened for 5 minutes in Kodak Hardener

3.2

c ,9

~ 2.4

i

0.8

o,o~ ____ ~ ____ ~~ ____ ~ ______ ~~ __ ~~ __ ~~ 0.20 0.40 0.80

Original density

FIG. 2. Original density vs density after intensification for Type K film. X 10 minutes' intensification. 0 5 minutes' intensification.

SH-l (formula given below), and again washed for 5 minutes. They are then ready for treatment, one at a time, in the intensifier (formulas given below), which is made by taking 1 part of solution

TABLE 1. Formulas.

Kodak Special Hardener SH-1

Water Kodak formaldehyde. about 37% solution

by weight Kodak sodium carbonate. monohydrated Water to make

Kodak Quinone-Thiosulfate Intensifier In-6

Solution A • Water (about 70°F)

Sulfuric acid (concentrated) Kodak potassium bichromate Water to make

Solution B • Water (about 70°F)

Kodak sodium bisulfite Kodak hydroQuinone Kodak Photo-Flo solution Water to make

Solution C • Water (about 70°F)

Kodak sodium thiosulfate (hypo) Water to make

500 cc

10.0 cc 6.0 g 1.01

750 cc 30.0 cc 22.5 g

1.01

750 cc 3.8 g

15.0 g 3.8 cc 1.01

750 cc 22.5 g

1.01

• The water nsed for mixing the solutions for the intensifier should not have a chloride content greater than about 15 parts per million (equIvalent to about 25 parts of sodium chloride per miIlion); otherwise. the intensifica­tion wiII be impaired. If in doubt as to chloride content. use distiIIed water.

A, to which are added 2 parts of solution B, then 2 parts of solu­tion C, and finally 1 part of solution A. It is important that the mixing of the intensifier is followed in this order. Maximum intensification is reached after about 10 minutes' treatment, with frequent agitation, after which the intensified film is washed 20 to 30 minutes and dried as usual.

The intensified image is destroyed by acid hypo, so that under no circumstances should the intensified negatives be placed either in the fixing baths or in wash water contaminated with fixing bath.

The stock solutions will keep for several months in stoppered bottles, and the mixed intensifier is stable for 2 or 3 hours. The bath should be used only once and then discarded, because a used bath may produce a silvery scum on the surface of the image.

1 L. E. Muehler and J. 1. Crabtree. J. Photo Soc. Am. 11. Nos. 2 and 3, (1945),

Cylindrical Light Scattering Cell L. P. WITNAUER AND H. J. SCHERR

Eastern Regional Research Laboratory" and Department of Chemistry. Temple University.t Philadelphia, Pennsylvania

(Received September 17, 1951)

Z IMMI has described a method for measuring high molecular weights by light scattering from solutions or suspensions.

The method requires no assumption of a particle shape. It consists in measuring the intensity distribution of scattering over as great an angular range as possible and then extrapolating to zero angle. This paper describes the construction and performance of a cylindrical cell for making such measurements down to angles as low as 22° to the incident beam. The cell is designed specifically for the B-S photometer2 but can be adapted for use with other in­struments by making obvious modifications in the dimensions.

A scale drawing of the cell is shown in Fig. 1. The body of the cell is a 12-cm length of 41-mm O. d. standard wall Pyrex tubing. The tubing is free from obvious defects. The tube is ground length­wise to give a pair of parallel windows, 8 mm wide, with both the inner and outer faces flat. One-half of the tube is frosted over its full inside length to reduce multiple reflections of stray light. A circular glass plate is fused to one end of the tube as a bottom. The bottom of the cell is cemented into a square plastic base which fits the stage of the B-S light-scattering photometer and aligns the entrance and exit faces with respect to the incident light.

To produce the inner faces of the windows the glass tubing is rubbed on a brass lap with an abrasive mixed with glycerine or water. Grinding is done in three stages using three laps, each with a different abrasive. The abrasives were, successively, American Optical Company Numbers 180, 302, and 304 (cerium oxide). The laps were made from brass stock t in.X 1 in.X 14 in., with the grinding surface reduced in width from t in. to 8 mm. A series of grooves -h in. wide and t in. apart is cut in the lap surface at an angle of 45° to the sides. One end of the lap is clamped in a vise, the tube slipped over the other end, and the grinding done with a back-and-forth stroke. The first or rough grinding operation is stopped when the curved inner surface of the tube is essentially fiat. The second and third grinding operations using finer abrasives serve to smooth and flatten the inner faces and greatly facilitate

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FIC, 1. Diagram of cylindrical light-scattering cell.

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