“I did suggest it,” Oppenheimer responded, “but not on [that] ground… Why I chose the name is not clear, but I know what thoughts were in my mind. There is a poem of John Donne, written just before his death, which I know and love. From it a quotation:
The poem was Donne's “Hymne to God My God, in My Sicknesse,” and among its subtleties it construes a complementarity that parallels the complementarity of the bomb that Bohr had recently revealed to Oppenheimer. (“Bohr was deeply in this,” Bethe testifies, “and this was his real interest, and Bohr had long conversations with Oppenheimer which brought Oppenheimer into this at a very early stage. Oppenheimer was very much indoctrinated by Bohr's ideas of international control.”) That dying leads to death but might also lead to resurrection — as the bomb for Bohr and Oppenheimer was a weapon of death that might also end war and redeem mankind — is one way the poem expresses the paradox.
“That still does not make a Trinity,” Oppenheimer's letter to Groves goes on, “but in another, better known devotional poem Donne opens, ‘Batter my heart, three person'd God; —.’ Beyond this, I have no clues whatever.” Nor must Groves have had; but the fourteenth of Donne's
That is poetry perhaps martial enough, ardent enough and sufficiently fraught with paradox to supply a code name for the first secret test of a millennial force newly visited upon the world.
Oppenheimer did not doubt that he would be remembered to some degree, and reviled, as the man who led the work of bringing to mankind for the first time in its history the means of its own destruction. He cherished the complementary compensation of knowing that the hard riddle the bomb would pose had two answers, two outcomes, one of them transcendent. Such understanding justified the work at Los Alamos if anything did, and the work in turn healed the split between self and overweening conscience that hurt him. He had long recognized the possibility of such a convalescence and evoked it explicitly in the epistle on discipline he wrote his brother Frank in 1932 that concluded in Pauline measure: “Therefore I think that all things which evoke discipline: study, and our duties to men and to the commonwealth, war, and personal hardship, and even the need for subsistence, ought to be greeted by us with profound gratitude; for only through them can we attain to the least detachment; and only so can we know peace.” At Los Alamos, if only for a time, he located that detachment in duties to men and to the commonwealth that Bohr was teaching him to believe might be worthy, not macabre. He was not the first man to find himself in war.
To develop implosion Los Alamos had to develop diagnostics, ways to see and to measure events that began and ended in considerably less time than the blink of an eye. The iron pipes Seth Neddermeyer imploded could be studied by aiming a high-speed flash camera down their bores, but how could the physicists of G Division observe the shaping of a detonation wave as it passed through solid blocks of high explosives, or the compression of the metal sphere which those explosives completely surrounded? They were competent research scientists who had been working within narrow technological constraints for a year and a half; diagnostics demanded imagination and they brought all their frustrated creativity to the task.
X-raying was a reliable approach; the Ordnance Division had already used X rays to study the behavior of small spherical arrangements of explosives. X rays reveal differences in density — dense bone casts a darker shadow than lighter flesh — and since the detonation wave of a developing implosion changed the density of the explosive material as it burned its way through, X rays could make that wave visible. But adapting X-ray diagnostics to implosion studies on an increasing scale meant protecting fragile X-ray equipment from the repeated blasts of as much as two hundred pounds of high explosives at a time. That challenge the physicists met by the unorthodox expedient of mounting their implosion tests between two closely spaced blockhouses with the X-ray unit in one building and the radiography equipment in the other, accessible to the test event through protected ports. Ultimately flash X-ray equipment — high-current X-ray tubes that pulsed as rapidly as every ten-millionth of a second — proved most useful for detonation-wave studies.
The behavior of a test unit's HE shell was easier to study with X rays and high-speed photography than was the compression of its denser metal core. For following the metal core as it squeezed to less than half its previous volume Los Alamos developed several different diagnostic methods and used them in complement.
One method set the test unit within a magnetic field and measured changes in field configuration as the metal sphere compressed. Since HE is essentially transparent to magnetism, this method allowed the physicists eventually to study full-scale assemblies. It gave reliable measure of shock waves reflected from the core and of the troublesome detonation-wave intersections that caused jets and spalling.
Carefully spaced prearranged wires contacted by the metal sphere as it imploded supplied information not only about the timing of the implosion but also about material velocities at various depths within the core. That provided direct, quantitative data which the Theoretical Division could use to check how well its hydrodynamic theory fit the facts. The Electric Method group began by measuring the high-explosive acceleration of flat metal plates. Early in 1945 it adapted its techniques to partial spheres and eventually to spheres surrounded by HE lens systems with only one lens removed to access the necessary wires.
Duplicated at another test site, the blockhouse arrangement that served to protect ordinary X-ray equipment also served to shield the most unusual diagnostic method the scientists devised: firing pulsed X rays from a betatron through scale-model implosion units into a cloud chamber and photographing the resulting ionization tracks with a stereoscopic camera.[8] The betatron method needed an ingenious timing circuit to trigger in quick but precise sequence the explosive charge, the betratron X-ray pulse, the expansion of the diaphragm of the cloud chamber that made the ionization tracks visible as droplets in the fog and the camera shutters that photographed them.
The fifth successful method G Division developed varied the betatron method by incorporating an intense source of gamma radiation within the core itself. The source, radioactive lanthanum extracted from among fission products of the Oak Ridge air-cooled pile, gave the method its name: RaLa. Not a cloud chamber but alignments of rugged ionization chambers served to register the changing patterns of radiation from the RaLa cores as they compressed. Since no one knew at first how extensively the radio-lanthanum would contaminate the test site, Luis Alvarez, who coordinated the first experiment, borrowed two tanks from the Army's Dugway Proving Ground in Utah to use as temporary blockhouses. He recalls spectacular results:
I was sitting in the tank when the first explosion went off. George Kistiakowsky was in one tank and I was
