by Tom Clancy
* * *
Dawkins finished his first circuit of the stadium just as Minnesota made its second touchdown. Again it was Wills, this time a four-yard pass out of the backfield. The guy already had fifty-one yards rushing and two receptions. Dawkins found himself looking at the ABC van he'd checked through. Why the Colorado tags? They'd said they were from Chicago, and that they had brought the tape widget in from Omaha. But the truck was painted like an official network truck. The local TV stations were not network-owned. They all showed network affiliation, but the big letters on them were for the local call-letters for the stations. Something to ask the sarge about. Dawkins circled the entry on his clipboard and wrote a question-mark next to it. He walked inside to the security booth.
“Where's the sarge?”
“Out walking the lot,” the officer at the booth replied. “The dumbass has twenty bet on the Chargers. I don't think he can take it.”
“I'll see if I can get him to lay a little more,” Dawkins replied with a grin. “Which way did he go?”
“North, I think.”
“Thanks.”
* * *
The Vikings kicked off again, with the score 14-0. The same return man took the kick, this time three yards deep in the end zone. He ignored the safety man's advice to down the ball and went up the middle like a shot. Breaking one tackle at the sixteen, he took advantage of a picture-book block and broke for the sidelines. Fifteen yards later it was clear that only the kicker had a chance, but the kicker was slow. At one hundred three yards, it was the longest kick return in Superbowl history. The point after was good, and the game was now 14-7.
“Feeling better, Dennis?” the Secretary of State asked the Secretary of Defense.
Bunker set his coffee down. He had decided not to drink. He wanted to be stone sober when he accepted the Lombardi Trophy from the Commissioner.
“Yeah, now we just have to figure a way to stop your boy.”
“Good luck.”
“He's a great kid, Bruce. Goddamn if he can't run.”
“He isn't just an athlete. Kid's got brains, and a good heart.”
“Bruce, if you educated him, I know he's smart,” Bunker said generously. “I just wish he'd pull a hamstring right about now.”
* * *
Dawkins found his sergeant a few minutes later. “Something funny here,” he said.
“What's that?”
“This truck — little white van on the east end of the row of big satellite trucks, 'ABC' painted on it. Colorado commercial tags, but supposedly it's from Chicago or maybe Omaha. I check 'em through, said they had a tape deck to replace a broken one, but when I walked past it a few minutes ago, it wasn't hooked up, and the guys who brought it in were gone.”
“What are you telling me?” the sergeant asked.
“I think it might be a good idea to check it out.”
“Okay, call it in. I'll give it a walk-past.” The sergeant looked at the clipboard to check the tag number. “I was headed off to help out the Wells Fargo guys at the loading dock. You take that for me, okay?”
“Sure, Sarge.” Dawkins headed off.
The watch supervisor lifted his Motorola radio. “Lieutenant Vernon, this is Sergeant Yankevich, could you meet me down at the TV place?”
Yankevich started walking back south around the stadium. He had his own personal radio, but it lacked an earpiece. San Diego stopped the Vikings on downs. Minnesota punted — a good one that required a fair catch at the Chargers' thirty. Well, maybe his team could get the game even. Somebody ought to shoot that Wills kid, he thought angrily.
Officer Dawkins walked to the north end of the stadium and saw a Wells Fargo armored car parked at the lower-level loading dock. One man was trying to sling out bags of what had to be coins.
“What's the problem?”
“The driver's beat his knee up, he's off having it fixed. Can you give me a hand?”
“Inside or outside?” Dawkins asked.
“You hand them out, okay? Be careful, they're heavy mothers.”
“Gotcha.” Dawkins hopped inside. The interior of the armored truck was lined with shelves holding innumerable bags of mainly quarters, it looked like. He lifted one, and it was as heavy as he'd been told. The police officer stuck his clipboard in his belt and went to work, handing them out to the loading dock, where the guard set them on a two-wheel hand-truck. Trust the sarge to stick him with this.
Yankevich met the Lieutenant at the media entrance. Both walked over to the truck in question. The Lieutenant looked inside. “A big box with 'Sony' written on it… wait a minute. Says it's a commercial videotape machine.”
Sergeant Yankevich filled his boss in on what Dawkins had told him. “It's probably nothing, but—”
“Yeah — but. Let me find the ABC guy. I'm also going to call the bomb squad. Stay here and keep an eye on the thing.”
“I have a Slim Jim in my car. If you want, I can get in easy enough.” Every cop knows how to break into cars.
“I don't think so. We'll let the bomb guys think it over — besides, it's probably just what it looks like. If they came down to replace a broken tapedeck — well, maybe the broken one was fixed and they decided they didn't need it.”
“Okay, Lieutenant.” Yankevich walked inside to get another cup of coffee to keep warm, then returned to the out-of-doors he loved so much. The sun was setting behind the Rockies, and even in zero weather with a bitter wind, it was always something beautiful to watch. The police sergeant walked past the network uplink vans to watch the glowing orange ball dip through one of the blowing snow clouds. Some things were better than football. When the last edge of the sun dipped below the ridge line, he turned back, deciding to take another look at the box inside the truck. He would not make it.
35
THREE SHAKES
The timer just outside the bomb case reached 5:00:00, and things began to happen.
First, high-voltage capacitors began to charge and small pyrotechnics adjacent to the tritium reservoirs at both ends of the bomb fired. These drove pistons, forcing the tritium down narrow metal tubes. One tube led into the Primary, the other into the Secondary. There was no hurry here, and the objective was to mix the various collections of lithium-deuteride with the fusion-friendly tritium atoms. Elapsed time was ten seconds.
At 5:00:10, the timer sent out a second signal.
Time Zero.
The capacitors discharged, sending an impulse down a wire into a divider network. The length of the first wire was 50 centimeters. This took one and two-thirds nanoseconds. The impulse entered a dividing network using kryton switches — each of them a small and exceedingly fast device using self-ionized and radioactive krypton gas to time its discharges with remarkable precision. Using pulse-compression to build their amperage, the dividing network split the impulse into seventy different wires, each of which was exactly one meter in length. The relayed impulses required three-tenths of a shake (three nanoseconds) to transit this distance. The wires all had to be of the same length, of course, because all of the seventy explosive blocks were supposed to detonate at the same instant. With the krytons and the simple expedient of cutting each wire to the same length, this was easy to achieve.
The impulses reached the detonators simultaneously. Each explosive block had three separate detonators, and none of them failed to function. The detonators were small wire filaments, sufficiently thin that the arriving current exploded each. The impulse was transferred into the explosive blocks, and the physical detonation process began 4.4 nanoseconds after the signal was transmitted by the timer. The result was not an explosion, but an implosion, since the explosive force was mainly focused inward.
The high-explosives blocks were actually very sophisticated laminates of two materials, each laced with dust from light and heavy metals. The outer layer in each case was a relatively slow explosive with a detonation speed of just over seven thousand meters per second. The explosive wave in each expanded radially from the de
tonator, quickly reaching the edge of the block. Since the blocks were detonated from the outside-in, the blast front traveled inward through the blocks. The border between the slow and fast explosives contained bubbles — called voids — which began to change the shock-wave from spherical-shaped to a planar, or flat wave, which was refocused again to match exactly its metallic target, called “drivers.”
The “driver” in each case was a piece of carefully-shaped tungsten-rhenium. These were hit by a force wave traveling at more than nine thousand eight hundred meters (six miles) per second. Inside the tungsten-rhenium was a one-centimeter layer of beryllium. Beyond that was a one-millimeter thickness of uranium 235, which though thin weighed almost as much as the far thicker beryllium. The entire metallic mass was driving across a vacuum, and since the implosion was focused on a central point, the actual closing speed of opposite segments of the bomb was 18,600 meters (or 11.5 miles) per second.
The central aiming point of the explosives and the metallic projectiles was a ten kilogram (22 pound) mass of radioactive plutonium 239. It was shaped like a glass tumbler whose top had been bent outwards and down towards the bottom, creating two parallel walls of metal. Ordinarily denser than lead, the plutonium was compressed further by the million-atmospheres pressure of the implosion. This had to be done very quickly. The plutonium 239 mass also included a small but troublesome quantity of plutonium 240, which was even less stable and prone to pre-ignition. The outer and inner surfaces were slammed together and driven in turn towards the geometric center of the weapon.
The final external act came from a device called a “zipper.” Operating off the third signal from the still-intact electronic timer, the zipper was a miniature particle accelerator, a very compact mini-cyclotron that looked remarkably like a hand-held hair-dryer. This fired deuterium atoms at a beryllium target. Neutrons traveling ten percent of the speed of light were generated in vast numbers and traveled down a metal tube into the center of the Primary, called the Pit. The neutrons were timed to arrive just as the plutonium reached half of its peak density.
Ordinarily, a material weighing roughly twice an equivalent mass of lead, the plutonium was already ten times denser than that and still accelerating inward. The bombardment of neutrons entered a mass of still-compressing plutonium.
Fission.
The plutonium atom has an atomic weight of 239, that being the combined number of neutrons and protons in the atomic nucleus. What began happened at literally millions of places at once, but each event was precisely the same. An invading “slow” neutron passed close enough to a plutonium nucleus to fall under the Strong Nuclear Force that holds atomic nuclei together. The neutron was pulled into the atom's center, changing the energy state of the host nucleus and kicking it into an unstable state. The once symmetrical atomic nucleus began gyrating wildly and was torn apart by force fluctuations. In most cases a neutron or proton disappeared entirely, converted to energy in homage to Einstein's law E = MC2. The energy that resulted from the disappearance of the particles was released in the form of gamma and X-radiation, or any of thirty or so other but less important routes. Finally, the atomic nucleus released two or three additional neutrons. This was the important part. The process that had required only one neutron to start released two or three more, each traveling at over 10 percent of the speed of light—20,000 miles per second — through space occupied by a plutonium mass two hundred times the density of water. The majority of the newly-liberated atomic particles found targets to hit.
A chain-reaction merely means that the process builds on itself, that the energy released is sufficient to continue the process without outside assistance. The fission of the plutonium proceeded in steps called “doublings.” The energy liberated by each step was double that of the preceding one, and that of each subsequent step was doubled again. What began as a trivial amount of energy and just a handful of freed particles doubled and redoubled, and the interval between steps was measured in fractions of nanoseconds. The rate of increase — that is, the acceleration of the chain reaction — is called the “Alpha,” and is the most important variable in the fission process. An Alpha of 1,000 means that the number of doublings per microsecond is a vast number, 21000—the number 2 multiplied by itself one thousand times. At peak fission — between 250 and 253—the bomb would be generating 10 billion billion watts of power, one hundred thousand times the electrical-generating capacity of the entire world. Fromm had designed the bomb to do just that — and that was only ten percent of the weapon's total designed output. The Secondary had yet to be affected. No part of it had yet been touched by the forces only a few inches away.
But the fission process had scarcely begun.
Some of the gamma rays, traveling at the speed of light, were outside the bomb case while the plutonium was still being compressed by the explosives. Even nuclear reactions take time. Other gamma rays started to impact on the Secondary. The majority of the gammas streaked through a gas cloud that only a few microseconds earlier had been the chemical explosive blocks, heating it far beyond the temperatures chemicals alone could achieve. Made up of very light atoms like carbon and oxygen, this cloud emitted a vast quantity of low-frequency “soft” X-rays. To this point, the device was functioning exactly as Fromm and Ghosn had planned.
The fission process was seven nanoseconds—0.7 shakes — old when something went wrong.
Radiation from the fissioning plutonium blazed in on the tritium-impregnated lithium-deuteride that occupied the geometric center of the Pit. The reason Manfred Fromm had left the tritium extraction to last lay in his basic engineer's conservatism. Tritium is an unstable gas, with a half-life of 12.3 years, meaning that a quantity of pure tritium will, after that time, be composed half of tritium and half of 3He. Called “helium-three,” 3He is a form of that second-lightest of elements whose nucleus lacks an extra neutron, and craves another. By filtering the gas through a thin block of palladium, the 3He would have been easily separated out, but Ghosn hadn't known about that. As a result, more than a fifth of the tritium was the wrong material. It could hardly have been a worse material.
The intense bombardment from the adjacent fission reaction seared the lithium compound. Normally a material half the density of salt, it was compressed to a metallic state that exceeded the density of the earth's core. What began was actually a fusion reaction, though a small one, releasing huge quantities of new neutrons, and also changing many of the lithium atoms into more tritium, which broke down—“fused”—under the intense pressure to release yet more neutrons. The additional neutrons generated were supposed to invade the plutonium mass, boosting the Alpha and causing at least a doubling of the weapon's unboosted fission yield. This had been the first method of increasing the power of the second-generation nuclear weapons. But the presence of 3He poisoned the reaction, trapping nearly a quarter of the high-energy neutrons in uselessly stable helium atoms.
For several more nanoseconds, this did not matter. The plutonium was still increasing its reaction rate, still doubling, still increasing its Alpha at a rate only expressible numerically.
Energy was now flooding into the Secondary. The metallically-coated straws flashed to plasma, pressing inward on the Secondary. Radiant energy in quantities not found on the surface of the sun vaporized but also reflected off elliptical surfaces, delivering yet more energy to the Secondary assembly, called the Holraum. The plasma from the immolated straws pounded inward towards the second reservoir of lithium compounds. The dense uranium 238 fins just outside the Secondary pit also flashed to dense plasma, driving inward through the vacuum, then striking and compressing the tubular containment of more 238U around the central container which held the largest quantity of lithium-deuteride/tritium. The forces were immense, and the structure was pounded with a degree of pressure greater than that of a healthy stellar core.
But not enough.
The Primary's reaction had already slackened. Starved of neutrons by the presence of the 3He poison, the bomb's
explosive force began to blow apart the reaction mass as soon as the physical forces reached their balance. The chain reaction reached a moment of stability, at last unable to sustain its geometric rate of growth; the last two chain-reaction doublings were lost entirely, and what should have been a total Primary yield of seventy thousand tons of TNT was halved, halved again, and in fact ended with a total yield of eleven thousand two hundred tons of high explosive.
Fromm's design had been as perfect as the circumstances and materials allowed. An equivalent weapon less than a quarter the size was possible, but his specifications were more than adequate. A massive safety factor in the energy budget had been planned for. Even a thirty kiloton yield would have been enough to ignite the “sparkplug” in the Secondary to start a massive fusion “burn,” but thirty-KT was not reached. The bomb was technically called a “fizzle.”
But it was a fizzle equivalent to eleven thousand two hundred tons of TNT. That could be represented by a cube of high explosives seventy-five feet high, seventy-five feet long, and seventy-five feet thick, as much as could be carried by nearly four hundred trucks, or one medium-sized ship — but conventional explosives could never have detonated with anything approaching this deadly efficiency; in fact, a conventional explosion of this magnitude is a practical impossibility. For all that, it was still a fizzle.
As yet no perceptible physical effects had even left the bomb case, much less the truck. The steel case remained largely intact, though that would rapidly change. Gamma radiation had already escaped, along with X-rays, but these were invisible. Visible light had not yet emerged from the plasma cloud that had only three “shakes” before been over a thousand pounds of exquisitely designed hardware… and yet, everything that was to happen had already taken place. All that remained now was the distribution of the energy already released by natural laws which neither knew nor cared about the purposes of their manipulators.
