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James Van Allen journal, 1951?-December 1954

Page 21

Therefore, from this very crude (and not well justified) analysis, the efficiency of the ABC array appears to be  0.77 ± 0.10
[Error indicates at least half a chance of lying inside.]

Total range in table 0.67 [right arrow]   0.84. But x = 2.5 is definitely reasonable from a graphical check.
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Helvetica Physica Acta XXI, pages 200-203 (1948).
H. Waffler and O. Hirzel, E. [T? J?]. H., Zurich

"Relative Wirkungsguerschnitte für den ((gamma), n) Progess mit der Lithium Gamma-Strahlung (Quantenenergie (h)(v) = 17.5 mev)"

Relative ((sigma)((gamma)(n)))
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(N exponent 14)          0.3
(O exponent 16)          0.3
(Mg exponent 24)       1.3
(Al exponent 27)         2.7
(Fe exponent 54)        38
(Cu exponent 63)      100
(Zn exponent 64)        62
(Ag exponent 109)    176
(Au exponent 197)    ~460
(Si exponent 28)        0.7

Absolute (sigma)'s were determined by measuring the counting rate of a thick walled aluminum G. M. tube per W. A Fowler, C. C. Lauritsen and [T? J?]. Lauritsen; Rev. Mod Physics 20, page 236 (1948)

((sigma) sub 175) ((gamma),n) = 1.2 ± (0.3 x (10 exponent -25))  (cm exponent 2).

for (C exponent 63)

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Therefore, from this very crude (and not well justified) analysis, the efficiency of the ABC array appears to be 0.77 ± 0.10 [Error indicates at least half a chance of lying inside.] Total range in table 0.67 [right arrow] 0.84. But x = 2.5 is definitely reasonable from a graphical check. ------------------------------------------------------ Helvetica Physica Acta XXI, pages 200-203 (1948). H. Waffler and O. Hirzel, E. [T? J?]. H., Zurich "Relative Wirkungsguerschnitte für den ((gamma), n) Progess mit der Lithium Gamma-Strahlung (Quantenenergie (h)(v) = 17.5 mev)" Relative ((sigma)((gamma)(n))) ------------------------------------------ (N exponent 14) 0.3 (O exponent 16) 0.3 (Mg exponent 24) 1.3 (Al exponent 27) 2.7 (Fe exponent 54) 38 (Cu exponent 63) 100 (Zn exponent 64) 62 (Ag exponent 109) 176 (Au exponent 197) ~460 (Si exponent 28) 0.7 Absolute (sigma)'s were determined by measuring the counting rate of a thick walled aluminum G. M. tube per W. A Fowler, C. C. Lauritsen and [T? J?]. Lauritsen; Rev. Mod Physics 20, page 236 (1948) ((sigma) sub 175) ((gamma),n) = 1.2 ± (0.3 x (10 exponent -25)) (cm exponent 2). for (C exponent 63)