Preface to the Fourth Edition
To readers who have purchased this and possibly earlier editions of this book, I
thank you. Your support, suggestions, comments, and criticisms have made each
edition better than the preceding one. This will likely be the final edition of The
Physics of the Manhattan Project, and it incorporates a number of revisions, various
new graphs, four new sections, updated data, and clarifications and corrections of a
number of points. These revisions reflect my own increased knowledge of the
subject matter and a number of helpful suggestions contributed by readers who took
time to contact me.
Revisions and new material in this edition include:
• Fundamental data on the Little Boy and Fat Man bombs are now gathered into a
Preamble.
• In Sect. 1.8, the discussion of the number of fission-liberated neutrons above a
given energy threshold has been clarified.
• The discussion of the fission barrier in Sect. 1.10 has been revised to bring it
closer to Bohr and Wheeler’s original analysis. Updated data on fission barriers
has been incorporated throughout the book.
• The discussion of tamped criticality in Sect. 2.3 has been significantly improved
with the inclusion of several new graphs. An entirely new Sect. 2.4 discusses
composite tamped cores, that is, ones comprising shells of two different fissile
materials enclosed within a tamper.
• Numerical simulations of the Little Boy and Fat Man bombs (now Sect. 2.6)
incorporate improved physical modeling and updated information on real core
and tamper masses.
• Section 2.8 is also new, comprising four subsections on approximate methods of
estimating critical masses and yields. These methods are less rigorous than their
counterparts in the preceding sections of this chapter but are intended for use in
a classroom setting where time restrictions may not permit a fuller development.
• Section 3.3 on plutonium production has been simplified and clarified.
• Section 4.1 on boron contamination in graphite has been significantly revised to
correct some errors in previous editions.
vii
To readers who have purchased this and possibly earlier editions of this book, I
thank you. Your support, suggestions, comments, and criticisms have made each
edition better than the preceding one. This will likely be the final edition of The
Physics of the Manhattan Project, and it incorporates a number of revisions, various
new graphs, four new sections, updated data, and clarifications and corrections of a
number of points. These revisions reflect my own increased knowledge of the
subject matter and a number of helpful suggestions contributed by readers who took
time to contact me.
Revisions and new material in this edition include:
• Fundamental data on the Little Boy and Fat Man bombs are now gathered into a
Preamble.
• In Sect. 1.8, the discussion of the number of fission-liberated neutrons above a
given energy threshold has been clarified.
• The discussion of the fission barrier in Sect. 1.10 has been revised to bring it
closer to Bohr and Wheeler’s original analysis. Updated data on fission barriers
has been incorporated throughout the book.
• The discussion of tamped criticality in Sect. 2.3 has been significantly improved
with the inclusion of several new graphs. An entirely new Sect. 2.4 discusses
composite tamped cores, that is, ones comprising shells of two different fissile
materials enclosed within a tamper.
• Numerical simulations of the Little Boy and Fat Man bombs (now Sect. 2.6)
incorporate improved physical modeling and updated information on real core
and tamper masses.
• Section 2.8 is also new, comprising four subsections on approximate methods of
estimating critical masses and yields. These methods are less rigorous than their
counterparts in the preceding sections of this chapter but are intended for use in
a classroom setting where time restrictions may not permit a fuller development.
• Section 3.3 on plutonium production has been simplified and clarified.
• Section 4.1 on boron contamination in graphite has been significantly revised to
correct some errors in previous editions.
vii