” 3 . . math 1th ‘” at eae Tae? pas wee ~ i — 5 Table4, 1 gives for the spectre. studied. the exposure times the-totak yield’ fa kilotons ; ands t the wavelength ofthe cutoff, 6.g:, the wavelength at which the optical density felt te one-tenth . ~ “of!thasat about4100A.* A trend. in this cutoff toward longer. wavelengthe with a increase iat, seemsto|bepresent over thewhole yield. range studied; butit Ig doubtful that a scalingse= : Pa Baestablished at preadat: [n the second columm of Table 4.F,the exposuretimess:-:""= "peeegats ae-“total”cover the entire life of the fireball; appropriate designations of timesof: wee. * xposare+ made for shots where only a portion ofo the life of the Areballwas observed. a = Sate : - ry 3. COMPARISON Or c SPECTRAL INTENSITIES.FOROn NO,AND Nt. - woe, . , tee ee Mae "hee se . aid - The second very prominent feature in the Comparisonof these spectra is that the larger: the effective kilotonnage of the bomb, the stronger are the absorption lines or bands,.\.e.; for-.:. spectra of comparable exposure times. This isveryevident in. the Schumann-Runge system of oxygem from about 4600 A to the cutoff.’ These lines are relatively strong in Mike and Kingand . are considerably weaker for bombsof smaller yield. The lines are close together, with many: _ overlappings at the dispersion used, and, of course, since the intensities of the individual lines. . are different for the different shots, the appearances of the spectra are not always the same. In order to show an importantdifference between total-time shots and those taken atan _ early interval, Table 4.2 gives intensity values for the Schumann-Runge 0-13 band system in Buster Charlie and aleo for the same system in Tumbler-Snapper 3; Fig. 4.1 shows.the .- microphotometer traces for this region. (The Buster Charlie tracein Fig. 4.1 is taken from the report by J. Curcio, Atlas of High Dispersion Spectra Recorded at Buster-Jangle, NRL . ~ Report 4386 (RD 408), p. 20.] The exposure at Buster Charlie covered the first 20 msec of the-- . explosion, and Tumbler-Snapper 3 was a total-time exposure.. The rotational transition .--~ number “J” indicated for each wavelengthis that of the R-branch. The peak intensity for Buster Charlie occurs around J = 15 and for Tumbler-Snapper 3 at about J = 41. The intensity distri-, | bution of this rotational structure in Buster Charlie corresponds to a much lower temperature — than it does in the total-time Tumbler-Snapper 3. The effectiverotational temperatures range .. from a few hundred degrees Kelvin in Buster Charlie to several thousand degrees in Tumbler~ . Snapper 3. Table 4.3 shows a comparison of intensities of the lines of the S-R 0-15 band (head at: 3516 A) found in Tumbler-Snapper 3 (total), King (1.0 to 1.1 sec), Tumbler-Snapper 7 (0 to 100 usec), and Buster Charlie (0 to 20 msec). A plot of intensities of the peaks given in this table for King and Tumbler-Snapper 3 is shown in Fig. 4.2. In this plot no distinction is made between P and R branches; however, one can see that all points for King are about twice as ~ high on the intensity scale as are corresponding points for Tumbler-Snapper 3..The irregularities in the intensities for King around 3700 A are probably due to overlappings by the S-R 0-16 system. Microphotometer traces showing the S-R 0-15 band for the four shots are presented in Fig. 4.3. It is of intereat to note that in comparing the two short-time exposures (Buster Charlie and Tumbler-Snapper 7), the very early Tumbler-Snapper 7 exposure showathe band more strongly than does the 20-msec Buster Charlie exposure. This suggests that the band was excited by an early radiation surge. It should be noted, however, that the casing ma- terial in Buster Charlie was about( than in Tumbler-Snapper 7. The two large jumps in the Tumbler-Snapper 7 trace are due to HNO, absorption. For the mostpart, everything else seen in these four traces is due to S-R O, absorption. From the Mike plates it was difficult to obtain good intensities for the rotational distribu-—~ tion of any Schumann-Runge v-v transition because of the superposition of the NO, spectrum and the great breadth of the lines. The latter fuzziness is probably due to broadening conditions present in the explosion. In order to give some idea, however, of the way Mike compares with King (total), Greenhouse Dog, and Tumbler-Snapper 3, the intensities of two selected spectral” ranges have been compared for the four shots in Table 4.4.. These intensity values are only approximate, mainly because of the overlappinga of other bands. Microphotometer traces of absorption bands around this region (4000 to 4200 A) are shown in Fig. 4.4 for Mike, King, and Tumbler-Snapper 3. . 20 xO