briefly that I was going to meet my father in Munich and that I'd be back in a week. I bought the ticket and left for Germany.” She stopped for a moment, then continued.
“I waited at the pension for one day but nobody called. I didn't have Gideon's phone number in Israel. I called the Israeli Consulate and they didn't know what I was talking about. I knew something was wrong but I didn't know exactly what. When none of my calls were returned, I went to my father's hotel and asked the manager to take me to his room. His things were there, but there wasn't even a note to tell me where he'd gone. The manager said that my father might have been traveling. He didn't seem to think anything was wrong. So I decided to wait. Perhaps my father had had to leave unexpectedly. But as I returned to my pension I had a strange feeling that I was being followed. So I went to a bank, I changed some money, and I opened a safe-deposit box and put the letter there. I had a feeling that the whole mystery of my father's disappearance was somehow connected to the people who were following me.”
“That was a very wise move,” I said. “But why this next move – to Moscow?” I asked, directing the conversation back to the present.
“You don't know? I thought you were working together with Ilan from the consulate in Munich, and that he sent you here to protect me.” Her tone became suddenly suspicious. I knew I'd tripped; I was supposed to know. Damage control, quickly.
“I did come here to help you. I don't know everything, but isn't your visit connected to the Russian contacts your father was building?”
“Yes. So if you know, why are you asking these questions? Are you testing me? Is that it?”
“No, Ariel,” I said, trying to calm things down. “I'm simply trying to pull the story together. Tell me what you've accomplished so far.”
The waiter came again, cleared our plates, and opened a folding table. Whether we liked it or not, there was more food. Another waiter came carrying huge plates with a mountain of yellow rice, cubes of lamb, and grilled vegetables. It looked wonderful and smelled even better – a welcome change from stolid German food.
“I don't know if I should tell you. I want to keep it a secret. I don't need a replay of my shouting match with Ilan in Munich when I first told him I was going to Moscow, while he wanted me back in Israel.”
“That's fine with me,” I said agreeably.
“Mutual confidence must be built first,” were the words that Alex, my Mossad instructor, had used. “Never try to kiss on the first date.” I'd made a mistake by trying, but Ariel's story was exceptionally tempting. I had to play it safe for a while. Adam and Eve had been expelled from Eden for a lesser transgression.
In the back of my mind I feared that I was not being professional. These were the facts: While on the trail of plutonium-seeking Iranians I meet, for the first time, a woman who is also the daughter of DeLouise, who had contact with the Iranians. Now she suddenly mentions her research in nuclear physics. Could Ariel, with her expertise, be part of the Iranian conspiracy? According to my training, every alarm bell in my head should be going off. But they weren't. Was I accepting her story at face value? Did that mean I considered her trustworthy? Were my instincts right, or was I being lulled by my attraction to her beauty? I came to no conclusion other than to be careful, and to watch and wait.
“How long will you stay in Moscow?”
“I don't know yet, I need to see some people first.”
“Tell me more about your doctoral thesis.” I wanted our meeting to last longer.
Ariel chuckled, “How well do you know your physics?”
“Try me.” Only when I'd said it did I realize that my reply could go both ways.
“Now, that's going to take even longer than my kidnapping story,” said Ariel in a teasing tone. I didn't quite follow what she meant. It could have more than one meaning. But I kind of liked that idea.
“Go ahead,” I finally said.
“I'm working on the naturally occurring changes in plutonium.”
“You mean the radioactive metal?”
“Yes. Plutonium is one of the more mysterious and complex elements in nature. Although it can be found in nature, for nuclear-power purposes it must be manufactured in a process developed only fifty years ago. Have you ever seen plutonium?”
“No,” I admitted.
“OK, here's a quick course for beginners,” she said.
“Do I need to take notes?” I asked with a smile.
“No, and there'll be no exam at the end. Plutonium, element 94, is named after the planet Pluto. It was discovered in 1940 at Berkeley by the physicists Glenn Seaborg, Edwin McMillan, Joseph Kennedy, and Arthur Wahl.”
“Was that discovery part of the Manhattan Project that created the first atom bomb?”
“No,” she responded, “But it certainly led the use of plutonium in that project. Anyway, the isotope Pu-239 exists naturally in trace amounts in uranium ores. The quantity is really minute, only several parts per quadrillion.”
“I'm ashamed to ask, but how much is a quadrillion?”
“It's one thousand trillions or one followed by fifteen zeros.”
I nodded. “What big number comes after that?”
“Quintillion, that's one thousand quadrillion, or one followed by eighteen zeros.”
I looked at her eyes. They glittered when she talked about her work.
“So, isotope Pu-239 is produced by the capture of spontaneous fission neutrons by uranium-238. Extremely small amounts of plutonium-244, the longest-lived plutonium isotope, have been detected in cerium ore; apparently surviving residues of plutonium were present at the formation of Earth.”
I began to feel sorry that I'd skipped my physics classes in high school. Then I could ask Ariel an intelligent question and show interest in more than just her. That part of physics was not included in the nuclear overview at the Mossad Academy. I wasn't completely ignorant of the subject, however.
“Plutonium is produced in a process called ‘breeding,’ by bombarding uranium-238 with slow neutrons in a nuclear reactor. If a slow neutron is captured then uranium-239 is produced, and the compound then quickly decays into neptunium-239 and then plutonium.”
I nodded because I wanted to continue looking at her. In fact, everything she was telling me was somewhat familiar from my science classes at the Mossad Academy. But in the sciences you had to run twice as fast just to hold the same ground; otherwise, the others would pass you – and I didn't run. I had to admit that I'd gotten out of the science race immediately after my Mossad training.
Ariel continued. “Plutonium is silvery in color and naturally warm. But when you expose it to the atmosphere it changes color to yellow. One of the reasons that plutonium is so complex is the great number of its stable structures. Carbon, for example, has three, while plutonium has six, each with a different density, and they change in accordance with temperature.”
She paused and looked at me with curiosity. “Did you understand any of it?”
“Some,” I admitted. “Does your research have any practical applications?”
“Definitely,” she said. “Since plutonium changes its condition rapidly and each new version has different qualities, it is very difficult to control. You must control it if you want to use plutonium in a nuclear device.”
“Such as the big A?”
“Yes. American scientists at Los Alamos discovered that plutonium is stable when alloyed with aluminum and gallium. After the smelting and the cooling off, plutonium enters its most stable condition, known as ‘delta phase.’ This phase proved to be very convenient, because it made plutonium behave like a normal metal. It was unbreakable, did not corrode over time, and was simple to mold.”
“So what's the problem?” I asked.
“It's a problem of catastrophic magnitude,” said Ariel seriously, her blue eyes intent. “For years everybody believed that plutonium with aluminum and gallium alloy was the ultimate solution to handling plutonium. But Soviet scientists repeatedly claimed that with increased temperature, plutonium might change from delta phase to alpha phase. That is alarming, because alpha phase is far less stable and might induce a spontaneous chain reaction.”
“A chain reaction leading to a nuclear explosion?”
