Chapter Twenty-Eight

WILLY (Beryllium)

“I DON’T BELIEVE IT,” Ernest Rutherford told his Cavendish crew upon reading the report in the Comptes rendus by the team of Curie and Joliot. Of course he trusted the couple to tell the truth. He simply could not come to their conclusions. He felt certain they had misinterpreted their data.

James Chadwick, who was once Rutherford’s student at Manchester and now his colleague at Cambridge, took up the problem. Repeating the experiments tried in Giessen and in Paris, Chadwick, too, detected a super-penetrating emission from bombarded targets of beryllium and boron. But it was not gamma radiation. Instead, the powerful emission from the struck targets consisted of never-before-seen neutral nuclear particles—entities originally proposed by Rutherford in 1920.

These “neutrons,” Chadwick argued, had been dislodged from the nuclei of the light-element targets. As neutral particles, they avoided deflection by magnets. And since a neutron about equaled the size of a hydrogen nucleus, a neutron could readily knock a hydrogen ion out of a paraffin film.

The existence of neutrons did more than resolve the curious results of recent studies. All up and down the periodic table, neutrons proved the missing link between atomic number and atomic weight. The light target element beryllium, for example, at number four on the table, owed its established atomic weight, nine, to the presence of five neutrons in addition to its four positively charged particles, or protons. Neutrons thus supplied the long-sought “neutral ballast” needed to account for the weight differences between isotopes of any given element.

Among radioelements, neutrons solved the riddle of beta decay. Each neutron presumably consisted of a proton and an electron bound together, so that the breaking of that bond would free one electron for release from the parent element and, at the same time, add one unit of positive charge to the daughter product.

Irène and Frédéric had missed out on a major discovery. Despite their disappointment, they managed to see poetic justice in the revelation of Rutherford’s proposed neutral particle by Rutherford’s protégé, at Rutherford’s lab. As Frédéric later conceded in a lengthy interview, “the genius Rutherford” had presciently conceived “a hypothetical neutral particle which, together with protons, made up the nucleus.” Though it seemed far-fetched at the time, the idea had permeated “the atmosphere of the Cavendish Laboratory where Chadwick worked, and it was natural—and just—that the final discovery of the neutron should have been made there.”

Warming to his theme, Frédéric went on, “Old laboratories with long traditions always have hidden riches. Ideas expressed in days past by our teachers, living or dead, taken up a score of times and then forgotten, consciously or unconsciously penetrate the thought of the workers in these laboratories and, from time to time, they bear fruit: that is discovery.”

He and Irène consoled themselves that their day would come, facilitated by the “hidden riches” of the Curie lab. For now they welcomed the timely arrival of Pierre Joliot, born March 12, 1932, and described in the private journal of his mother as a plump baby with a little bit of chestnut-colored hair, a turned-up nose, and a wise air about him.

Irène, who had languished two weeks in bed following her first accouchement, and taken frequent rest periods necessitated by anemia, rebounded with surprising speed. Barely a month after giving birth, she felt well enough to attempt a strenuous new scientific pursuit. Leaving la petite Hélène and the infant Pierre behind, she and Frédéric set off for a research station perched on the Jungfraujoch in the Swiss Alps to investigate “cosmic rays.” Mysterious radiation from outer space was ionizing the upper reaches of the atmosphere—stripping electrons off air molecules and generating cascades of charged particles. This situation had been discovered with the help of electrometers carried first to the top of the Eiffel Tower and then to greater heights on balloon flights. Scientists, particularly radioactivists, were monitoring the activity from locations all over the world.

“We have already done quite a lot,” Irène wrote Marie on May 1, after a week of measuring ionization currents under various weather conditions. “Fred works with the Pohl electrometer and I with the Wulf. This way we can tell the real variations from random signals in one of the devices.” She compared their surroundings to “a magnificent nest of glaciers.” For once she was not sorry that Marie could not join them. The very thin air above eleven thousand feet caused them headaches and insomnia, she said, while the extreme cold kept them bundled in their ski clothes round the clock. Plus, only one walking path was accessible at this time of year.

Frédéric spared his own mother the worrisome details. “It’s a dream to work so comfortably in this fine Institute,” he wrote her, praising the view, the food, and the occasional opportunities for skiing on the glaciers. “However, we are sorry not to be with you, and to be deprived of Hélène and Pierre.”

WHILE IRÈNE and Frédéric hunted cosmic rays, Marie, now sixty-four, was walking with a neighbor on a familiar trail in Cavalaire when she tripped and fell and broke her arm. She developed a fever on top of the injury, and the combination kept her stranded, under medical care, for two weeks beyond the scheduled end of her brief vacation. “I shudder to think of the disruption caused by my absurd accident,” she fretted to Irène. “What will I find when I return to Paris!” She implored Irène “to look after Mlle. Lub”—Wilhelmina Lub, due any day from the University of Amsterdam—“to avoid giving her the impression of disarray at the very start of her stay.”

“Willy” Lub, the newest researcher, defended her doctoral thesis in Amsterdam on May 4, 1932, and presented herself at the Curie Lab on the tenth. She came with the special endorsement of her mentor, Pieter Zeeman, who deemed her one of his best students in forty years of teaching. Zeeman had shared the 1902 Nobel Prize in Physics with his mentor, Hendrik Lorentz, for revealing the effect of magnetic fields on the appearance of spectral lines. He saw in the thirty-two-year-old Willy Lub “a lively intelligence and a great modesty.” There were times, he noted, when she went at her research with such zeal that he had intervened to slow her down for fear her health would suffer.

In Paris, Mlle. Lub accepted Madame’s challenge to determine the spectrum of actinium. Three decades after André Debierne’s discovery of the element, the Curie lab had yet to accumulate enough actinium to settle its atomic weight, visualize its spectrum, and cement its place on the periodic table. Actinium was not only exceedingly rare but also extremely difficult to extract from pitchblende by chemical means.

Before this project could begin in earnest, and notwithstanding her broken arm, Marie went to Warsaw at the end of May with Dr. Claudius Regaud for the opening ceremonies at the Marie Sklodowska-Curie Radium Institute and Hospital. She even posed for a picture wielding a shovel, seemingly planting a tree with Dr. Regaud in front of the new building while Dr. Bronya Sklodowska-Dluska and the current president of Poland, chemist Ignacy Mościcki, looked on.

Bronya now filled her late husband’s intended place as director of the institute. As someone who managed her grief by keeping busy, she ran scant risk of having too little to do. Marie, too, knew the solace—and the strain—of stepping into a deceased loved one’s shoes. “Even though you feel lonely,” she told Bronya, “you have one consolation: there are three of you in Warsaw, for companionship and protection. Believe me, family solidarity is what matters most. I was deprived of it, so I know.” Of course Marie’s siblings had rushed to her side when Pierre died, but then, of necessity, they had gone home. “Take comfort from the ones close, and don’t forget your Parisian sister. Let’s see each other as often as possible.”

Mme. Curie and Dr. Claudius Regaud at the Radium Institute in Warsaw

Musée Curie (coll. ACJC)

Curiethérapie for cancerous tumors had begun months ahead of the hospital’s official opening, using the gram of radium purchased in 1929 with the US gift of $50,000. Marie had seen the cost of radium cut in half between her two trips to America, and new veins of high-grade uranium ore found recently near Canada’s Great Bear Lake promised another price reduction. True to her established practice of courting reliable radium sources, Marie was already negotiating with mine owners in the Northwest Territories.

A cheaper supply of radium to meet the medical demand would also, alas, aid the purveyors of dangerous, unregulated nostrums such as the radium-containing Radithor. American steel magnate Eben Byers, who boasted that he drank three bottles of Radithor per day to boost his vitality and sexual prowess, suffered a gruesome death by radium poisoning in 1932.

In France, the Tho-Radia product line touted “a scientific approach to beauty” in glowing print advertisements for radioactivity-enhanced cold cream and face powder that purportedly erased signs of aging. Worse, Tho-Radia’s claims were backed by the fictitious authority of “Dr. Alfred Curie.” Ève sought legal counsel on Marie’s behalf, in defense of the family name. To confront the bogus “Dr. Curie,” the real Mme. Curie was advised to compose a clarifying statement on Laboratoire Curie stationery—using her own words but incorporating the phrases provided as a guide—then sign the document and send it to the managers of every important publication in the country.

AT LEAST PART of the reason Irène and Frédéric had failed to recognize the neutron, they rationalized, was their lack of the latest instrumentation. James Chadwick at the Cavendish had augmented his ionization chamber with an amplifier and oscillograph that helped him perceive the particulate nature of the radiation from the bombarded targets. The Joliot-Curie couple, unwilling to be outpaced again by anyone, set about upgrading their ionization chambers, electrometers, and other equipment.

Since the days of her doctoral research, Irène had often relied on devices called “cloud chambers,” invented by Scottish meteorologist C. T. R. Wilson, for tracking the paths of subatomic particles. In the same way that real clouds formed from the condensation of water vapor around dust particles, the moist air inside a cloud chamber collected around ions. Particles shooting through the chamber stripped electrons off the gas molecules they passed, ionizing them. Each of these ions seeded a tiny cloud, and together the cloud puffs marked the intruders’ paths. A magnetic field around the chamber caused the paths to veer one way or the other in the case of charged-particle projectiles. An observer could photograph the telltale trails through a small glass window in the chamber.

Frédéric devised a variable-pressure cloud chamber. By reducing the pressure inside to extremely low levels—approaching one-hundredth that of the air in the lab—he could lengthen the distances that particles traveled, making the images easier to decipher.

In mid-August that summer, just six months after the debut of the neutron, observations with a cloud chamber brought a second new subatomic particle to light. This happened not in the Curie lab but at the California Institute of Technology, where American physicist Carl Anderson captured compelling evidence for an anti-electron—an electron with positive charge. Anderson called his electron-sized, positively charged particle a “positron.”

In the wake of that announcement, Irène and Frédéric reviewed several of their own cloud-chamber photographs, where they had seen what looked like electrons moving in the wrong direction through a magnetic field. Early in 1933, with considerable remorse, they reclassified these errant electrons as positrons.

For the second time in the space of one year, a discovery within their reach had eluded their grasp.