The Koon shot of

Operation Castle Operation Castle was a United States series of high-yield (high-energy) nuclear tests by Joint Task Force 7 (JTF-7) at Bikini Atoll beginning in March 1954. It followed ''Operation Upshot–Knothole'' and preceded '' Operation Teapot''. Con ...

was a test of a

thermonuclear device A thermonuclear weapon, fusion weapon or hydrogen bomb (H-bomb) is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lowe ...

designed at the

University of California Radiation Laboratory Lawrence Berkeley National Laboratory (LBNL, Berkeley Lab) is a federally funded research and development center in the hills of Berkeley, California, United States. Established in 1931 by the University of California (UC), the laboratory is spo ...

(UCRL), now

Lawrence Livermore National Laboratory Lawrence Livermore National Laboratory (LLNL) is a Federally funded research and development centers, federally funded research and development center in Livermore, California, United States. Originally established in 1952, the laboratory now i ...

. The "dry" two-stage device was known as "Morgenstern" and had a highly innovative secondary stage. It was tested on 7 April 1954. The predicted yield was between 0.33 and 3.5 megatons, with an expected yield of 1 megaton. The actual yield was 0.11 megatons. Morgenstern was thus a fizzle. Post-shot analysis showed that the failure was caused by the premature heating of the secondary by the

neutron flux The neutron flux is a scalar quantity used in nuclear physics and nuclear reactor physics. It is the total distance travelled by all free neutrons per unit time and volume. Equivalently, it can be defined as the number of neutrons travelling ...

of the primary. This was a simple design defect and not related to the unique geometry of the secondary. The UCRL's other shot, the "wet" (i.e., cryogenic) ramrod device, originally scheduled for the ''Echo'' shot, was cancelled because it shared the same design defect. The name "Morgenstern" (

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

for morning star) was chosen because of the shape of the secondary. The secondary consisted of a central sphere from which spikes were radiating, resembling a morning star / mace. The spikes may have been an idea from physicist

Edward Teller Edward Teller (; January 15, 1908 – September 9, 2003) was a Hungarian and American Theoretical physics, theoretical physicist and chemical engineer who is known colloquially as "the father of the hydrogen bomb" and one of the creators of ...

and colleagues to use implosive jets to compress the thermonuclear

core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...

. It was more than two decades before weapons were designed that utilized a secondary concept similar to that first tested in the Koon shot.

References

*Hansen, Chuck, "The Swords of Armageddon: U.S. Nuclear Weapons Development since 1945" (CD-ROM). PDF, 2,600 pages, Sunnyvale, CA, Chukelea Publications, 1995, 2007. (2nd Ed.) Explosions in 1954 Nuclear testing at Bikini Atoll 1954 in military history 1954 in the environment 1950s in the Marshall Islands 1954 in the Trust Territory of the Pacific Islands April 1954 in Oceania {{US-mil-stub