A physicists guide to The Los Alamos Primer

Reed, B. Cameron

doi:10.1088/0031-8949/91/11/113002

Cited by 8 publications

(1 citation statement)

References 20 publications

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“…As no experimental data of prompt-gamma multiplicity distribution is available for fast neutron fission (E n = 4.3 MeV here, see below) of Pu-239, so to calculate the number of photons in our concerned energy range, GEF nuclear reaction code, version 2018/1.1 7 was used to calculate the prompt γ-spectrum from the neutron-induced fission of Pu-239 core. In the Manhattan Project, neutron sources utilized (α, n) reaction, where an α-emitting element is mixed with a low Z material, usually Be-9 14,15 . In such a reaction, the average energy of the neutron emitted is 4.3 MeV.…”

Section: Calculation and Resultsmentioning

confidence: 99%

Estimating the photo-fission yield of the Trinity Test

Khan¹

2020

Sci Rep

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Estimating the photo-fission yield of the Trinity Test f. A. Khan in the Trinity Test, the energy was released not only from the fission of Pu-239 core but also from the fast neutron fission of tamper surrounding it. The high energy photons produced from the fissioning core can also induce fission in U-238 tamper. In this work, an effort has been made, for the first time, to develop an approach to investigate the possibility of photon-induced fission in U-238 tamper used in Trinity Test nuclear weapon. GEF nuclear reaction code, version 2018/1.1 is used to calculate the prompt γ-spectrum from the fast fission of Pu-239 core of the device. It is estimated that 14.5 ton (t) of TNT of the total 21 kT yield of the Trinity nuclear device is contributed by the photo-fission of U-238 tamper. When the first nuclear device, called the Gadget, was tested in 1945, there were several comments regarding the amount of energy released in the test. The device worked on the fission induced by fast neutrons (E ~ MeV) and so do all the modern nuclear devices. Its design, except some minor changes, was the same as that of the one used on Nagasaki-an implosion-type plutonium based device 1 , using 6.19 kg of highly enriched plutonium 2. Only when the photographs of the Trinity Test fireball, taken by Julian Mack and his team, were declassified, the British physicist Sir G. I. Taylor studied the problem of nuclear explosion in detail and obtained the expression for the energy released. He gave two values of yield as 16.8 kT and 23.7 kT 3,4. The energy released from the Trinity Test nuclear device was not only from the neutron-induced fission of Pu-239, but also from the fission of U-238 tamper by fast neutrons (E ~ MeV) released from the Pu-239 fissioning core 5. A tamper is a heavy material surrounding the fissile material core, that not only reduces its critical mass, when added sufficiently, by reflecting neutrons back to the fissioning core, but also retards the inevitable expansion of the core, allowing more time for fissions to occur until the core density drops to the value where criticality no longer holds. In Gadget, the plutonium core, besides highly explosive chemicals, was wrapped by about 120 kg natural uranium tamper 5. In addition to other forms of energy, the fissioning core also releases fast neutrons and prompt γs. So, keeping in view the formation of γs, it becomes interesting to study whether there is any contribution in the energy released from the γ-induced fission of U-238 tamper. While looking for the literature relevant to the γ-induced fission of U-238 etc. tamper in a nuclear device, I have not come across any research article. In the present work, an approach is developed to investigate the possibility of photon-induced fission of U-238 tamper generated by the fission of Pu-239 core of the Trinity nuclear device. U-238 nuclei can undergo fission by such photons, particularly in the Giant Dipole Resonance (GDR) energy region 6. Here, GEneral Fission (GEF) nuclear reaction code 7-9 is used to calculate the pr...

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Section: Calculation and Resultsmentioning

confidence: 99%