The recent success of efforts by staff in the Accelerator-Based Low-Energy Program to produce element 116, a critical milestone in the search for element 120, has garnered much attention. An article about the achievement was recently published by the Washington Post (paywalled).
A second article, this one published by APS’s This Week in Physics, presents a brief overview of the search for superheavy elements, inspired by the latest LBNL results.
Towards the Discovery of New Elements: Production of Livermorium (Z=116) with 50Ti
Is there an end to the periodic table? How many protons and neutrons can fit into a nucleus? What is the heaviest element that can exist? Is there an ‘island of stability’, where superheavy elements have unique properties and long lifetimes? The quest to discover new elements not only looks towards answering these questions, but also pushes the boundaries of our understanding of atomic structure, stability, and the forces that hold matter together. Currently, there are 118 elements known, of which 90 exist naturally on Earth. Elements heavier than fermium (100 protons) are made by combining the nuclei of two lighter elements, but not just any combination works. The five heaviest known elements today were produced by combining nuclei of a special isotope of calcium (20 protons and 28 neutrons) with actinide element nuclei. Unfortunately, this method only works up to element 118 (Oganesson). To go beyond, scientists must find a new reaction mechanism.
In a paper recently accepted to Physical Review Letters, The Heavy Element Group at Berkeley Lab’s Nuclear Science Division made a significant breakthrough. Using a beam of titanium-50 (22 protons, 28 neutrons) accelerated in the 88-Inch Cyclotron, the team successfully produced two atoms of the superheavy element Livermorium (element 116) in 22 days. This experiment marks a key step towards creating element 120 which is expected to be 10-20 times harder to make than Livermorium. If successfully made, element 120 would be the heaviest known element, occupying the eighth row of the periodic table, and edging closer to the “island of stability”. Exploring elements at the extremes can provide insights into how atoms behave, test models of nuclear physics, and map out the limits of atomic nuclei.
This work was led by Jacklyn Gates and Rodney Orford of the Nuclear Science Division’s Heavy Element Group. The collaboration includes researchers from Berkeley Lab, Lund University, Argonne National Laboratory, Lawrence Livermore National Laboratory, San José State University, University of Strasbourg, University of Liverpool, Oregon State University, Texas A&M University, UC Berkeley, Oak Ridge National Laboratory, University of Manchester, ETH Zürich, and the Paul Scherrer Institute.
Figure 1: Observed decays of 290Lv and its daughters (left) compared to the known decay properties of 290Lv (right)
Figure 2: An expanded periodic table shows where researchers expect elements 119 and 120 to be categorized if they are discovered. Credit: Marilyn Sargent/Berkeley Lab
NSD Research Scientist Jennifer Pore Receives DOE Early Career Research Award
NSD Research Scientist Jennifer Pore has been selected to receive funding through the DOE Office of Science Early Career Research Program. Dr. Pore’s project, “Investigating the Fundamental Properties of the Heaviest Elements,” will be at the intersection of Nuclear Physics and Chemistry and utilize LBNL’s Berkeley Gas-Filled Separator (BGS) and FIONA devices to study the physical and chemical properties of Superheavy Elements. Funding for the five year award will be jointly provided by the DOE Office of Science Nuclear Physics and Basic Energy Sciences programs. Further details can be found here.
In Memorium – Frank Samuel Stephens Jr.
It is with deep sadness that we have learned of the passing of Frank Stevens on Sunday, August 18, 2024. Frank will be remembered for the enormous impact on the field of Low Energy Nuclear Physics. He started at Berkeley Lab as a Research Chemist in 1955, became a Senior Scientist two years into his career at the Lab, and was appointed as a Distinguished Scientist in 1995 before retiring from a career with many highlights in 1997. Frank was an inspiration to those he worked with. He will be greatly missed.
Our thoughts are with his family at this difficult time. An obituary and further information can be found here: https://www.grandstaff-hentgen.com/obituary/frank-stephens-jr
A New Way to Make Element 116 Opens the Door to Heavier Atoms
Researchers at the 88-Inch Cyclotron successfully made superheavy element 116 using a beam of titanium-50. That milestone sets the team up to attempt making the heaviest element yet: 120.
Today, an international team of researchers led by Berkeley Lab’s Heavy Element Group announced that they have made known superheavy element 116 using a titanium beam, a breakthrough that is a key stepping stone towards making element 120. The result was presented today at the Nuclear Structure 2024 conference; the science paper will be posted on the online repository arXiv and has been submitted to the journal Physical Review Letters.
GRETA Makes Its First Move
In May, the Gamma-Ray Energy Tracking Array (GRETA) project achieved a significant milestone with the move of the two mechanical assemblies that comprise the array structure. These structures moved from their assembly location in the high-bay of Bldg. 88 to the laboratory ‘K-area’ space where they will be integrated with the other technical systems of GRETA in the coming months.
This move happened in the beginning of May over the course of two days. Following detailed planning over several months with the LBNL rigging team led by Curt Howard and Taylor Silva, including the procurement of dedicated gantry cranes and measuring far more than twice, the move started bright and early at 8am on May 7, 2024. The planning more than paid off with an impressively smooth move of these >6000 lb assemblies. Figures 1 through 5 show a story-board of the move of the first structure. A lift onto a flatbed truck in the Bldg. 88 high-bay started the action, then travel around the building followed. A truck-mounted 50-ton crane was used to lift the structures off the flat-bed and to perform the delicate drop through the double doors into the K-area. The GRETA structures were then rolled into position alongside their final places and a coordinated lift and slide of the structures using the dedicated pair of gantry cranes completed the move on to the prepared plates. The pair of installed structures is shown in Figure 6. The LBNL riggers with support from the local Bldg. 88 mechanical crew, in particular John Garcia and Brian Bell, executed this complex move perfectly, twice.
Over the coming summer months, the GRETA structures will be built up with motion and cooling systems, aligned, and then load tested. Six GRETA Quad Module HPGe detectors will be installed in the August-September timeframe to demonstrate the performance of the array prior to completion of the DOE project and its ultimate delivery to the Facility for Rare Isotope Beams (FRIB) for scientific operation.
NSD scientist Paul Fallon is the GRETA Project Director and Heather Crawford is the manager for GRETA System Assembly, with staff from NSD and Engineering Division at LBNL, and from ANL, ORNL and FRIB on the project team.
Figure 1: The first half assembly of the GRETA mechanical structure being craned in the Bldg. 88 high-bay onto a flatbed truck for transport around the building.
Figure 2: The mechanical structure loaded on the flatbed and ready to roll with NSD DSC Jeff Bramble looking on.
Figure 3: The first half assembly staged on the west side of Bldg. 88 and ready for craning off the truck and into the K-area.
Figure 5: The first of the two GRETA mechanical assemblies being slid over on dedicated gantry cranes onto the prepared mounting surface.
Figure 6: The final pair of installed GRETA mechanical assemblies in the K-area at Bldg. 88.