Big Science: The Discovery of Tennessine

Big Science:

The Discovery

of Tennessine

January 27, 2017

Oak Ridge National Laboratory Team

Scientiﬁc Discovery

Charles Alexander

Porter Bailey

Dennis Benker

Jeﬀery Binder

Rose Boll

Julie Ezold

Kevin Felker

Robert Grzywacz

Krzysztof Miernik

Curtis Porter

Frank Riley

James B. Roberto

Krzysztof P. Rykaczewski

Robin Taylor

Technical and Specialty Support

John Arthur

Rod Brewer

Christopher Bryan

Doug Canaan

Fred Chattin

Jason Cook

Mike Cooke

Jess Copeland

David J. Dean

Jeﬀery Delashmitt

David Denton

Sergio Dukes

Krystee Ervin

Wayne Evans

Mitch Ferren

Gary Galloway

W. Doyle Garrett

Joseph Giaquinto

Bennie Goodman

Michael A. Green

Joe Guy

Nicky Hatton

LeRoy Hicks

Greg Hirtz

Randy Hobbs

Douglas Keener

Ben Lewis

Stephen Lyles

Dairin Malkemus

Deborah Mann

Tom McConnell

Angela McGee

Steve Meyers

Marty Milburn

Rob Morgan

Karen Murphy

Charlie Nevius

John Norman

Jim Parﬁtt

Margaret Parker

Curt Porter

Tim Raley

Rob Smith

Shawn Smith

Allen Smith

Andy Souders

Lucia L. Spears

Eddie Sutherland

Ed Turnington

Roger Underwood

Shelley Van Cleve

Roger Weaver

Gary West

Ken Wilson

Quinn Windham

Brad Woody

Timothy A. Zawisza

Oak Ridge National Laboratory recognizes and thanks our

partner institutions in this collaborative eﬀort

The Joint Institute for Nuclear Research, Dubna, Russia

Vanderbilt University

The University of Tennessee, Knoxville

Lawrence Livermore National Laboratory

The Research Institute for Advanced Reactors, Dimitrovgrad, Russia

University of Nevada, Las Vegas

BIG SCIENCE:

The Discovery of Tennessine

The international eﬀort to create superheavy element

117—Tennessine—began in late 2004 when Yuri

Oganessian of the Joint Institute for Nuclear Research

(JINR) in Dubna, Russia, proposed the experiment to the

Department of Energy’s Oak Ridge National Laboratory.

Oganessian had developed a “hot fusion” method

of bombarding actinide targets with a neutron-rich

calcium-48 beam that had resulted in the synthesis,

and thus discoveries, of elements 114, 115, 116 and

118. A “cold fusion” method of bombarding lead or

bismuth with heavy ions had produced elements

106 through 113.

Synthesizing element 117 to ﬁll the remaining square in row seven of the

Periodic Table required a target of the radioisotope berkelium-249 (Bk-249),

which in theory would produce the short-lived element if relentlessly bom-

barded with a calcium-48 beam at JINR’s Gas-Filled Recoil Separator.

Berkelium-249, however, is an exclusively man-made material attainable as a

byproduct of the production of californium-252 (Cf-252), another synthetic

radioisotope used in medicine and industry. ORNL is the world’s only source

of Bk-249 in suﬃcient quantities for the proposed experiment. Bk is typically

produced as a byproduct of Cf-252, which was not in production in February

2005, when Oganessian visited ORNL. Still, a collaboration between JINR,

ORNL, Lawrence Livermore National Laboratory, and Vanderbilt University was

proposed to await the next campaign to separate Cf-252 for the Department

of Energy’s isotope program.

Yuri Oganessian

Vanderbilt’s advocate for the element 117 experiment was physics professor

Joe Hamilton, who has a history of collaboration with ORNL going back to

the establishment of the University Isotope Separator at Oak Ridge in the

early 1970s and the Joint Institute for Heavy Ion Research that involved ORNL,

Vanderbilt and the University of Tennessee in the early 1980s.

When a Cf-252 campaign materialized at ORNL in 2008,

Hamilton informed Oganessian and introduced him to

Jim Roberto, ORNL’s director of Scientiﬁc and Technology

Partnerships, whose materials research interests include

heavy element nuclear physics. Roberto, in turn, set in

motion the eﬀort to retrieve Bk-249 for the element 117 exper-

iment during the Cf-252 campaign. Roberto and Oganessian

agreed to coordinate the Bk-249 eﬀort with the JINR acceler-

ator’s availability.

Lawrence Livermore National Laboratory also joined the project. LLNL had

collaborated with JINR in the discoveries of superheavy elements 114, 116 and

118. Element 116 was later named livermorium after the California lab.

ORNL’s nuclear expertise and capability to produce exotic radioisotopes

originated with the laboratory’s World War II mission to demonstrate the

production of plutonium in a nuclear reactor. That Manhattan Project work

was rapidly accomplished: The X-10 Graphite Reactor reached criticality on

November 4, 1943, and demonstrated the production and separation of gram

quantities of plutonium. Large-scale plutonium production was undertaken

at Hanford, Wash., and a plutonium test device was detonated in the New

Mexico desert on July 16, 1945.

The scientists who were assembled for the urgent wartime project lost no

time in mining the reactor’s potential for scientiﬁc research and established

important groundwork for nuclear medicine, neutron scattering science, and

the nuclear power industry. E.O. Wollan performed early neutron diﬀraction

experiments at the Graphite Reactor, which he pursued with Cliﬀord Shull.

Shull eventually shared the Nobel Prize for Physics based on this pioneering

neutron science work.

Jim Roberto

Chemical separation science was

also integral to the success of the

Manhattan Project. One byproduct

of the quest for a nuclear weapon

was the separation of the theorized

lanthanide element 61 at ORNL.

The team of discoverers, which

included Charles Coryell, Larry

Glendenin and Jacob Marinsky,

named the new element “prome-

thium,” inspired by the mythologi-

cal Prometheus, who stole ﬁre from

heaven to beneﬁt mankind.

Radiochemistry and isotope pro-

duction have remained leading

scientific capabilities at ORNL.

ORNL is one of the world’s largest

producers of rare radioisotopes,

with much of the work centered

at the High Flux Isotope Reactor,

where targets are irradiated, and

the adjoining Radiochemical

Engineering Development Center,

where the radioisotopes are pro-

cessed, separated and puriﬁed.

The radioactive, neutron-emitting isotope Cf-252 is produced through an

8-month exposure of americium and curium targets to the world’s highest

steady-state neutron ﬂux. After being irradiated at HFIR, the targets are pro-

cessed at REDC. Berkelium-249 can also be obtained in the process.

With a Cf-252 program on the horizon, Roberto, Oganessian and Hamilton

met in Nashville in 2008 to plan the experiment. The Department of Energy

approved the separation campaign in November, including production of

The accelerator complex at the Joint Institute

for Nuclear Research, Dubna, Russia.

Bk-249 for research purposes (i.e., discovering element 117). ORNL and JINR

agreed on a schedule for the experiment including transfer of the Bk-249 to

JINR, dedicated accelerator time for the experiment at JINR, and collaboration

in the related research.

Roberto asked Kzrysztof Rykaczewski, a nuclear physicist in ORNL’s Physics

Division, to help facilitate the international scientiﬁc eﬀort. Rykaczewski is a

veteran nuclear spectroscopist who has discovered more than 60 isotopes,

10 of them at ORNL, and represents decades of nuclear physics research and

experience in discovering new alpha and proton emitting isotopes. A native

of Poland who speaks Russian, Rykaczewski was also comfortable working

across borders.

The Bk-249 targets emerged from HFIR in January 2009 to begin the nearly six

months of processing, three of those simply to decay to a point they could be

handled. Processing requires several more months, which for the purposes

of the 117 experiment represented a considerable tax on Bk-249’s 330-day

half-life. REDC produced 22 milligrams

of Bk-249 with impurities of less than

one part in 10

, an achievement that

impressed researchers on the receiv-

ing end at Dubna.

REDC technicians captured a photo of

the rare radioisotope in a vial, the 22

milligrams of green ﬂuid competing

with the hot cell’s yellow lithium bro-

mide patina. REDC technicians com-

pleted the processing by mid-June,

and the shipping phase commenced.

The carefully packaged and labeled

shipment was separated into ﬁve par-

cels resembling large paint buckets.

ORNL (HFIR and REDC) produced

22 milligrams of berkelium-249,

shown in this vial, for the

element 117 experiment.

Rykaczewski worked with ORNL’s Isotope Business Oﬃce and a shipping

company to prepare the radioisotopes for transit, which included translat-

ing documents and obtaining approvals and permits. It was new territory:

Isotope shipments to Dubna typically involved materials with half-lives of

hundreds of years. Bk-249’s was less than a year. The packages embarked on

a nerve-wracking odyssey that included two round trips across the Atlantic

after the shipment was turned away twice. More time was lost when the

parcel was delayed for various, mostly bureaucratic, reasons.

Eventually, the Bk-249 parcels were delivered to Dimitrovgrad’s Research

Institute for Atomic Reactors for target preparation in what still is the fastest

transfer of actinides between the United States and Russia on record.

There were technical hitches, as well: The Russian team, which had requested

the radioisotope in the form of berkelium nitrate, initially had diﬃculty extract-

ing the Bk-249. They questioned at one point whether they really had Bk-249

and eventually resorted to a strong concoction of three acids, called “tsar

vodka,” to retrieve the radioisotope. The team then hand-painted the radio-

isotope onto the target because the original plan to electroplate it produced

unsatisfactory results.

Time on the Bk-249’s 330-day half-life was ticking away the whole time, but

the hand-painted target worked well, and on July 28 the targets were ﬂown to

Dubna to make up time, and the calcium-48 beam was applied to the target

at JINR’s Gas-Filled Recoil Separator.

In addition to the Bk-249, ORNL sent research staﬀ members to Dubna and

provided detectors, instruments and digital electronics for detecting short-

er-lived isotopes, the products of knowledge gained from decades of nuclear

physics work at ORNL. After 150 days of irradiation with a beam of 6 trillion

calcium-48 ions per second, the team reported it had detected six atoms of

element 117, which then decayed into elements 115, 113, 111, 109, 107 and 105.

“I really wanted to be sure. We were looking for a

very few events, and we knew what to look for in

our previous work.” — Krzysztof Rykaczewski

Rykaczewski, who spent weeks in Russia with the experiment, describes

obtaining the results:

“I really wanted to be sure. We were looking for a very few events, and we knew what

to look for from our previous work. We were sending 6 trillion projectiles per second

and on average we got one event per month—a chain of correlated alphas as they

decay in milliseconds at ﬁrst, then longer into seconds. It is a very distinct signature

correlated in space and in time. This is how we detect superheavy molecules—the

sequence of decays.

“The probability that it is random is 10

-6

,” or one in a million, Rykaczewski said. “It

cannot be random.”

The data analysis of the thousands of candidate reactions by Dubna and LLNL

researchers supported the existence, however ﬂeeting, of the half dozen

atoms of element 117. Authors representing JINR, RIAR, ORNL, LLNL, Vanderbilt

and the University of Nevada, Las Vegas announced the discovery on April 9,

2010, in Physical Review Letters. The publication also noted a strong rise in sta-

bility for superheavy isotopes (above Z=111), supporting the theorized Island

of Stability (see “Signiﬁcance of element 117” on page 9).

Conﬁrmation experiments followed the announcement. JINR, ORNL, LLNL,

Vanderbilt and the University of Tennessee, Knoxville (UTK) observed

an additional 14 atoms of element 117 at JINR in 2012 and 2013 using

berkelium from ORNL.

A group of scientists from 16 institutions in Australia, Finland, Germany, India,

Japan, Norway, Poland, Sweden, Switzerland, the United Kingdom and the

United States conducted conﬁrmation experiments to independently ver-

ify the discovery of element 117. This independent sighting of element 117,

which observed two atoms, was presented in a Physical Review Letters study

published in May 2014. The research involved the production—again—of

berkelium at ORNL and bombardment with high-power calcium ion beams

in an accelerator at GSI Helmholtz Centre for Heavy Ion Research in Darmstadt,

Germany. University of Tennessee professor Robert Grzywacz, a former

Eugene Wigner Fellow at ORNL, worked with ORNL to develop data acquisi-

tion technology that was used in the conﬁrmation experiments.

On Dec. 30, 2015, a committee comprising members of the International

Union of Pure and Applied Physics (IUPAP) and the International Union of

Pure and Applied Chemistry announced the criteria for the discovery of a new

element had been met and invited the collaborators to propose a name and

symbol to replace element 117’s working name of ununseptium.

There was precedent for naming

new elements after geographic

locations relevant to their discov-

eries (e.g., americium, californium,

livermorium, dubnium). The name

ultimately proposed—“tenness-

ine”—aligns with the halogen

group of the Periodic Table—ﬂuo-

rine, chlorine, bromine, iodine and

astatine in column 7A.

The symbol would be Ts. (The

more intuitive Tn is a discontin-

ued but sometimes used sym-

bol for tungsten.)

Because institutions in the state of

Tennessee played a major role in

the experiment, the collaboration

agreed that tennessine would be

an appropriate name for ununsep-

ORNL physicists developed this detection

system for superheavy element research.

tium, and on June 8, 2016, IUPAC’s Inorganic Chemistry Division published a

provisional recommendation for the name tennessine and symbol Ts.

After a ﬁve-month public review period, element 117 oﬃcially joined the

Periodic Table as tennessine on November 28, 2016, “in recognition of the con-

tribution of the Tennessee region, including Oak Ridge National Laboratory,

Vanderbilt University, and the University of Tennessee at Knoxville, to super-

heavy element research, including the production and separation of unique

actinide materials for superheavy element synthesis.”

In the same announcement, IUPAC oﬃcially named element 115 moscovium

in recognition of the Moscow region, home to JINR, and element 118 oga-

nesson, in recognition of Yuri Oganessian’s pioneering contributions to super-

heavy element research.

In addition to the berkelium-249 for element 117, ORNL-produced radioiso-

topes were used in the discoveries and conﬁrmations of superheavy elements

114 (Pu-244), 115 (Am-243), 116 (Cm-248) and 118 (Cf-249).

Signiﬁcance of element 117

In the current periodic table, elements beyond uranium (atomic

number of 92) are increasingly unstable and decay rapidly into

other elements.

Nuclear physicists beginning with nuclear pioneer Glenn

Seaborg have theorized an “island of stability” beyond the cur-

rent periodic table where new superheavy elements would

exhibit longer lifetimes. Such an island would extend the peri-

odic table to even heavier elements, and the increased lifetimes

would make chemistry experiments and potential applications

for these heretofore unknown elements increasingly practical.

Element 117 was the only missing element in row seven of the

periodic table. On course to the island of stability, researchers

initially skipped element 117 due to the diﬃculty in obtaining

the berkelium target material. The observed decay patterns

in the new isotopes from the element 117 experiments bring

scientists closer to the island of stability and continue a gen-

eral trend of increasing stability for superheavy elements with

increasing numbers of neutrons in the nucleus. The discovery

of element 117 provides strong evidence for the existence of

the island of stability.

A Special Eugene P. Wigner Distinguished Lecture

Recognizing the scientiﬁc discovery and naming of element 117 (tennessine)

Friday, January 27, 2017 • 3 to 5 p.m.

Iran Thomas Auditorium • Oak Ridge National Laboratory

Welcome and Introduction

Dr. Thom Mason, Director, Oak Ridge National Laboratory

■

Eugene P. Wigner Distinguished Lecture

Discovering Superheavy Elements

Dr. Yuri Oganessian

Scientiﬁc Leader, Flerov Laboratory of Nuclear Reactions,

Joint Institute for Nuclear Research

■

Question and Answer Session

Dr. Yuri Oganessian

Dr. Thom Mason

■

Screening of Element 117 Video

■

Remarks

Dr. Thom Mason

Dr. Timothy Hallman, Associate Director of Science, Oﬃce of Nuclear Physics,

US Department of Energy

Dr. Victor Matveev, Director, Joint Institute for Nuclear Research

Governor Bill Haslam, State of Tennessee

■

Announcement of Donation of Periodic Tables

Dr. Thom Mason

Governor Bill Haslam

■

Concluding Remarks

Dr. Thom Mason

Reception in the Spallation Neutron Source Lobby