“My friend,” Eisler said softly, “what do you think we are doing here? Why do you think we call it a gadget? Security code? I don’t think so. Maybe we don’t want to remind ourselves what it is we are making. Yes, twenty thousand tons. My calculations are quite precise. I would bet on it.” He smiled ironically. “Of course, we can’t yet calculate the dispersion. There are no good formulas for radioactivity. Even our Daniel recognizes that.”
Connolly felt stunned by the figures. They were calmly talking in a makeshift mess hall in the desert; the rest was beyond imagining. He could only fall back on the details of what was real, like a terminal patient still interested in medical procedure.
“Is that what you do too?” he asked. “Measure radioactivity?”
“Partly. We are not allowed to say, you know.”
“You work with Frisch in G Division, Critical Assemblies Group.”
Eisler flinched, surprised. “How do you know that?” Connolly didn’t say anything. “I see. Another test. So if you know, why do you ask?”
“I know where you work. I don’t know what it means.”
“So. Do you know fast neutrons? Do you know critical mass? How can I explain?” His eyes looked around the table, searching for props. “How much uranium do we need for the gadget-that’s the problem. We know it theoretically, but how to test the theory?” He moved Connolly’s coffee cup to the space between them. “Suppose this coffee were U-235. If we took enough, if we reached critical mass, there would be a chain reaction and, of course, the explosion. But when does that happen? So we take the coffee we think we need but we keep a hole in the middle-you must use your imagination here, I’m afraid-so the neutrons can escape. No reaction. The spoon will be the coffee we took out.” He held it over the cup. “If we lower it, like this, the neutron bombardment increases, the chain reaction accelerates. You have then the conditions for an atomic explosion.”
“But not the explosion.”
“We cheat a little-we use uranium hydride so it reacts more slowly. And we drop the slug very quickly. But yes, when we pass through the core,” he said, letting the spoon fall in, “we momentarily form a critical mass. It’s as close as we can come to an atomic explosion without having one. Of course, you can also produce this effect by simply stacking cubes of U-235 in a tamper of beryllium blocks. A critical assembly. But the other is more sophisticated. Perhaps also a little safer.”
Connolly stared at the coffee, then looked up at Eisler as if he were someone else. The last thing he had ever imagined him to be was daring. “You must have nerves of steel,” he said finally. “That’s like playing chicken.”
“Dragon,” Eisler corrected him.
“What?”
“We call it the Dragon Experiment-tickling the tail of the sleeping dragon.”
“And you don’t worry you’ll blow the place up?”
“No. We can control that. It’s the radiation that’s dangerous.”
“Well, better you than me.”
“Mr. Connolly, please don’t be so impressed. It’s a scientific experiment, no more. I think sometimes we’re all tickling the dragon, just a little. Testing how far we can go. Don’t you feel that? It’s only-” he searched, “the radiation we don’t expect.”
“I guess,” Connolly said, feeling that Eisler was really talking to himself.
“And now may I ask you something?” Eisler said politely. “What do you do? You’re not a driver.” He anticipated Connolly’s protest with a dismissive wave of his hand. “Please. I know. Drivers don’t go to Weber’s for the music. Oppie wants to drive with you alone. That’s very unusual, you know. We notice things like that. You have my dossier. I assume others as well. What exactly are you doing here? Am I permitted to know? A government agent of some sort, I think. So there must be something wrong. What dragon are you tickling?”
Connolly was struck again by how different the emigres were. Their first assumptions were still those of the police state.
“No,” he said, “nothing like that. I’m just helping to investigate a murder.”
“Oh? Whose?” His voice was so controlled and deliberate that Connolly took it for indifference.
“A security officer named Bruner.”
Eisler sipped his coffee, saying nothing.
“Did you know him?”
“No. That is, I knew who he was. We are still a small community on the project. I was sorry to hear about it. I didn’t realize it was a security matter,” he said, the last an uninflected question.
“It may not be.”
Eisler raised his eyebrows in another question, but Connolly didn’t elaborate.
“But you don’t know who killed him?”
“Not yet.”
“I see,” he said slowly, pushing aside his tray. “So you will be our sword of justice. Well, I wish you success in your hunt. To think of catching even one. So many dead these days, and never any killers.”
“I’m only looking for one in particular.”
“Yes, of course. Forgive me. I seem always to argue philosophy when you have work to do.”
“Are you married?”
