Book contents
- Frontmatter
- Contents
- List of Illustrations
- Preface
- 1 Introduction
- 2 Early Research on Fission: 1933–1943
- 3 The Early Materials Program: 1933–1943
- 4 Setting Up Project Y: June 1942 to March 1943
- 5 Research in the First Months of Project Y: April to September 1943
- 6 Creating a Wartime Community: September 1943 to August 1944
- 7 The Gun Weapon: September 1943 to August 1944
- 8 The Implosion Program Accelerates: September 1943 to July 1944
- 9 New Hopes for the Implosion Weapon: September 1943 to July 1944
- 10 The Nuclear Properties of a Fission Weapon: September 1943 to July 1944
- 11 Uranium and Plutonium: Early 1943 to August 1944
- 12 The Discovery of Spontaneous Fission in Plutonium and the Reorganization of Los Alamos
- 13 Building the Uranium Bomb: August 1944 to July 1945
- 14 Exploring the Plutonium Implosion Weapon: August 1944 to February 1945
- 15 Finding the Implosion Design: August 1944 to February 1945
- 16 Building the Implosion Gadget: March 1945 to July 1945
- 17 Critical Assemblies and Nuclear Physics: August 1944 to July 1945
- 18 The Test at Trinity: January 1944 to July 1945
- 19 Delivery: June 1943 to August 1945
- Epilogue
- 20 The Legacy of Los Alamos
- Notes
- Name Index
- Subject Index
15 - Finding the Implosion Design: August 1944 to February 1945
Published online by Cambridge University Press: 31 March 2010
- Frontmatter
- Contents
- List of Illustrations
- Preface
- 1 Introduction
- 2 Early Research on Fission: 1933–1943
- 3 The Early Materials Program: 1933–1943
- 4 Setting Up Project Y: June 1942 to March 1943
- 5 Research in the First Months of Project Y: April to September 1943
- 6 Creating a Wartime Community: September 1943 to August 1944
- 7 The Gun Weapon: September 1943 to August 1944
- 8 The Implosion Program Accelerates: September 1943 to July 1944
- 9 New Hopes for the Implosion Weapon: September 1943 to July 1944
- 10 The Nuclear Properties of a Fission Weapon: September 1943 to July 1944
- 11 Uranium and Plutonium: Early 1943 to August 1944
- 12 The Discovery of Spontaneous Fission in Plutonium and the Reorganization of Los Alamos
- 13 Building the Uranium Bomb: August 1944 to July 1945
- 14 Exploring the Plutonium Implosion Weapon: August 1944 to February 1945
- 15 Finding the Implosion Design: August 1944 to February 1945
- 16 Building the Implosion Gadget: March 1945 to July 1945
- 17 Critical Assemblies and Nuclear Physics: August 1944 to July 1945
- 18 The Test at Trinity: January 1944 to July 1945
- 19 Delivery: June 1943 to August 1945
- Epilogue
- 20 The Legacy of Los Alamos
- Notes
- Name Index
- Subject Index
Summary
The accelerated implosion effort, which began in August 1944, made rapid progress. By October 1944, James Conant was giving a lensed implosion device a 50–50 chance of working on schedule, if all went smoothly, for a test at Trinity on 1 May 1945 and a “3:1” chance for a test on 1 July. But he added, “In my opinion, the probabilities of success by the gun method (Mark 1) within the next year are very much greater than by the implosion method. Indeed the gun method seems as nearly certain as any untried new procedure can be.”
Overcoming asymmetries remained the outstanding technical problem of the implosion program. By mid-fall 1944, two experimental strands of the implosion program were converging on this problem: research on the explosive lens and on the electric detonator. In addition, in T-Division, Robert Christy put forth a conservative proposal for overcoming the asymmetry: try to implode a solid sphere rather than a spherical shell of active material. However, calculations indicated that the “Christy gadget” was intrinsically far less efficient than the hollow weapon, and that such a device would require a modulated initiator to activate the explosion at the most favorable moment. The call for the development of the implosion initiator added another thorny problem to the program.
As the time approached when sizable quantities of plutonium would become available, gross design features had to be frozen in order to begin final bomb production.
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- Critical AssemblyA Technical History of Los Alamos during the Oppenheimer Years, 1943–1945, pp. 293 - 314Publisher: Cambridge University PressPrint publication year: 1993