A view of FIONA's instrumentation. Credit: Marilyn Chung / Berkeley LabA group of nuclear physicists at the Department of Energy…
A view of FIONA’s instrumentation. Credit: Marilyn Chung / Berkeley Lab
A group of nuclear physicists at the Department of Energy Lawrence Berkeley National Laboratory (Berkeley Lab) has reported the first direct measurements of the mass numbers of the nuclei of two superheaval elements: moskov, which is element 1
15 and nihonium, element 113.
They obtained the results using FIONA, a new tool at Berkeley Lab, designed to solve the core and nuclear properties of the heaviest elements. The results are described in the November 28 issue of Physical Review Letters
FIONA is an acronym that means “for identification of nuclide A” with “A” representing the scientific symbol of an element’s mass number – the total number of protons and neutrons in an atomic nucleus. Protons are loaded positively and proton is also known as the atomic number; Neutrons have a neutral charge. Superheavy elements are human and have a higher atomic number than those found in naturally occurring elements.
The Global Race for Mass Number
Collecting and validating these first data from FIONA had been a top priority for Lab’s 88-inch cyclotron and nuclear science department since FIONA’s start-up began in early 2018. Cyclotron staff worked with visiting and domestic researchers to implement FIONA’s first experimental run, which spanned five weeks.
“It’s very exciting to see FIONA coming online because it’s extremely important to determine the masses of superheavy elements,” says Barbara Jacak, Director of Core Science. “Until now, mass assignments have been done with circumstances instead of direct measurement.”
Jackie Gates, a staff researcher at Berkeley Lab’s nuclear science department, who played a leading role in the perception, design and testing of FIONA, leading FIONA’s massive decision making efforts, said, “It has been very interesting to do an experimental measurement of superheavy mass number. “
Gates added that this effort to measure superheavy element masses is of global interest with teams from the Argonne National Laboratory and Japan’s nuclear research program among those who also make mass measurements of superheavy elements with some different methods or tools.
FIONA is a new system on the 88-inch cyclotron Berkeley Lab’s 88-inch cyclotron that allows direct mass number measurements of superheavy elements. Credit: Marilyn Chung / Berkeley Lab
Guy Savard, senior researcher at Argonne National Laboratory, designed, built and contributed several components to FIONA. He also helped FIONA and in his first scientific campaign.
Roderick Clark, senior scientist at Berkeley Lab’s nuclear science department, said: “Everyone gets together in this major competition. It can open a whole range of physics with these heavy and superheaval samples” as well as new studies of the structure and chemistry of these exotic elements, and a deeper understanding of how they tie with other elements. “
” If we can measure the mass of one of these superheavige elements, you can nail the entire region, “says Clark.
A new chapter in heavy element research
The mass number and atomic number (or “Z”) – a measure of the total number of protons in an atomic nucleus – of superheavy elements has relied on the accuracy of nuclear mass models. So it’s important to have a reliable way to measure these numbers with experiments if there is a problem with models, Ken Gregorich noted, a recently senior senior researcher at Berkeley Lab’s nuclear science department who worked near Gates to build and order FIONA. 19659005] For example, superheavy elements may display unexpected nuclei or densities of protons and neutrons not reported in the models, he says.
Berkeley Lab has made enormous contributions to the field of heavy element research: Lab researchers have played a role in the discovery of 16 elements on the periodic table, dating back to the synthesis of neptune 1940, and has also delivered hundreds of isotope identifiers. Isotopes are different forms of elements that share the same number of protons but have a different number of neutrons in their nuclei.
FIONA (see related article) is an addition to Berkeley Gas-Separated Separator (BGS). For decades, BGS has separated heavy elements from other types of charged particles that can act as unwanted “noise” in experiments. FIONA is designed to trap and cool individual atoms, separating them based on their mass and charge properties, and deliver them to an audio beam detector station for 20 milliseconds or 20,000 seconds.
Jackie Gates, left and Ken Gregorich, works with FIONA at early launch in 2017. Credit: Marilyn Chung / Berkeley Lab
“One atom per day”
“We can make an atom one day, give or take” a desired surprising element, noted Gregorich. In its early operation, FIONA was specifically tasked with capturing individual mosquito atoms. “We have a 14 percent chance to capture every atom,” he added. Thus, scientists had hoped to capture a single measurement of Mosquito’s mass number per week.
Moscovium was discovered in Russia in 2015 by a common American-Russian law which included researchers from the Lawrence Livermore National Laboratory and the discovery of nihonium is credited to a law in Japan in 2004. Element names were formally approved in 2016.
To produce mosquito bombed researchers at 88-inch cyclotron a target of americium, an isotope of an element discovered by Berkeley Labs Glenn T. Seaborg and others in 1944, with a particle beam prepared from the rare isotope calcium 48. The necessary half-calcium-48 was provided by the DOE isotope program.
There is a clear looping signature for each atom captured and measured by FIONA-lite as looking at a fixed point on a bicycle deck like the bicycle rollers forward. The course for this looping behavior is related to the atomic “mass-to-charge ratio”. The time and position of the energy signal measured in the detector tells the scientist the mass number.
Ideally, the measurement includes several steps in the particle decomposition chain: Moscovium has a half life of approximately 160 milliseconds, meaning that an atom has a 50 percent chance of decomposing another element called a “daughter” element in the decay chain was 160: e milliseconds. Capture its energy signature at several stages in This decay can confirm which parent atom started this cascade.
“We have been trying to create the mass number and proton number here for many years now,” says Paul Fallon, senior researcher at Berkeley Lab’s nuclear science department who heads the division’s low-energy program. The sensitivity of the detector has been steadily improved, as did the ability to isolate individual atoms from other noise, he noted. “Now we have our first final measurements.”  Confirming the Mass Number of Elements 113 and Elements 115
In FIONA’s first scientific round, researchers identified a muscular tomomy and its related deaths and a nihonium atom and its deaths. The measurements of atoms and decay chains confirm the predicted mass number for both elements.
While researchers had only attempted to create and measure the properties of a muscular atom, they could also confirm a measurement for nihonium after a Moscovium atom dropped to nihonium before it came to FIONA.
“The success of this first measurement is incredibly exciting,” says Jennifer Pore, a postdoctor who was involved in the FIONA launching experiment. “FIONA’s unique abilities have given a new renaissance of superheavy element research at the 88-th cyclotron.”
Gregorich credited the efforts of the staff at the 88-th cyclotron including mechanical, electrical, operational and control systems experts -to maximize the FIONA experiments during its first five-week scientific run.
He noted special contributions from other members of BGS and FIONA, including Greg Pang, a former project scientist involved in FIONA’s design and testing. Jeff Kwarsick, a PhD student whose doctorate thesis focuses on FIONA results; and Nick Esker, a former PhD student whose doctoral degree focused on mass-separator technology incorporated by FIONA.
Plans for New Measurements and Addition of “SHEDevil”
Fallon said another scientific run is planned for FIONA within the next six months, under which nuclear physics researchers can conduct a new measure of mosquito and nihonium or for other superheaval elements.
There are also plans to install and test a new tool called “SHEDevil” (for Super Heavy Element Detector for Extreme Ventures in Low Statistics) that helps researchers learn the shape of superheavy nuclear nuclei by detecting gamma rays produced in their maturity. These gamma rays will provide clues to the arrangement of neutrons and protons in the nuclei.
Measurement of the mass of superhuman, human-produced elements